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Background
The short-term efficacy of combined lifestyle and behavioural interventions led by nurses in the management of urinary incontinence has not been rigorously evaluated by randomized controlled trial. We conducted a 6-month randomized controlled trial to determine whether a model of service delivery that included lifestyle and behavioural interventions led by “nurse continence advisers” in collaboration with a physician with expertise in continence management could reduce urinary incontinence and pad use in an outpatient population. We also aimed to evaluate the impact of this approach on subjects'' knowledge about incontinence and their quality of life.Methods
We used advertising in the mainstream media, newsletters to family physicians and community information sessions in 1991 to invite volunteers who were 26 years of age or older and suffered from incontinence to participate in a randomized controlled trial. Men and women who met the eligibility criteria were randomly allocated to receive either counselling from specialized nurses to manage incontinence using behavioural and lifestyle modification sessions every 4 weeks for 25 weeks or usual care. Symptoms of incontinence and the use of incontinence pads were the primary outcome measures.Results
Using sealed envelopes, 421 patients were randomly allocated to the treatment or control groups. On average, patients in the treatment group experienced 2.1 “incontinent events” per 24 hours before treatment and 1.0 incontinent event per 24 hours at the end of the study. Control patients had an average of 2.4 incontinent events per 24 hours before the study and 2.2 incontinent events per 24 hours at the end of the study. The mean decrease in events in the treatment group was 1.2 and in the control group 0.2 (p = 0.001). Pad use declined from a mean of 2.2 per 24 hours before randomization in the treatment group to 1.2 per 24 hours at the end of the study, compared with 2.6 pads per 24 hours in the control group at the start of the study and 2.4 per 24 hours at the end. Pad use per 24 hours decreased on average by 0.9 pads in the treatment group and 0.1 in the control group (p = 0.021).Interpretation
Behavioural and lifestyle counselling provided by specialized nurses with training in managing incontinence reduces incontinent events and incontinence pad use.Urinary incontinence primarily affects young-to-middle-aged women and elderly men and women. The prevalence of urinary incontinence in people aged 65 years and older living in the community ranges from 8% to 30%.1,2,3,4,5,6 Urinary incontinence is underrecognized and those affected are often embarrassed and ashamed, thus, the problem frequently remains hidden.1,2North American and Canadian practice guidelines for the effective management of adult urinary incontinence have advocated thorough initial assessment, then staged multidisciplinary approaches beginning with the least invasive and reversible (lifestyle and behavioural) interventions, before drug therapy (reversible) and surgery (invasive and irreversible).1,2,3 The role of continence advisers in the management of urinary incontinence has evolved from its early beginnings in the United Kingdom7,8,9,10,11 and is now increasingly recognized in North America.12,13,14 There has been some evaluation of the short-term efficacy of multidisciplinary incontinence management by nurse practitioners or “nurse continence advisers” in community and outpatient settings.15,16,17,18,19,20 However, the short-term efficacy of combined lifestyle and behavioural interventions led by nurse continence advisers has not been rigorously evaluated using randomized controlled trials.Urinary incontinence has many causes, particularly in elderly people,21 and the potential for overall clinical improvement is greater when multiple interventions target several factors. Each intervention effects a small positive change, and these small changes cumulatively have a large positive outcome.21 Individual components of lifestyle and behavioural interventions are increasingly being shown to be effective. For example, behavioural training, including pelvic muscle exercises, has reduced urinary incontinence significantly,22,23,24 in some cases up to 57%.25 A combined approach consisting of both bladder training and pelvic muscle exercises, provided by trained registered nurses, has resulted in significantly fewer incontinent episodes than either approach alone.26 Pelvic floor exercises have been shown to be equally effective in women with stress, urge and mixed urinary incontinence.27 Adherence to pelvic floor muscle exercises has been shown to be sustained for up to 5 years in 70% of women who have intensive exercise training.28 Decreasing caffeine intake has also been shown to reduce episodes of incontinence.29 Reducing fluid intake in people with detrusor instability, but not those with genuine stress incontinence, reduces the number of “incontinent events.” Increasing fluid intake makes the urinary incontinence worse.30Our 6-month randomized controlled trial was conducted to determine whether a model of service delivery that included lifestyle and behavioural interventions led by nurse continence advisers in collaboration with a physician with expertise in continence management could reduce urinary incontinence and pad use. Our secondary aim was to investigate the impact of incontinence management led by nurse continence advisers on subjects'' knowledge about incontinence and their quality of life. 相似文献3.
BackgroundHealth systems planning is a challenging task, exacerbated by a lack of detailed information on the role played by family physicians, as indicated by practice variations across regions and demographic characteristics. Outcome measures used in past studies of family physician practice patterns were not uniform. Furthermore, past research has generally been limited to narrowly defined geographic regions. A national study of family physician practice patterns was undertaken to allow regional-level comparisons of clinical workload and range of medical services offered.MethodsThe 1997/98 National Family Physician Survey was mailed to a sample of 5198 Canadian family physicians and general practitioners (FP/GPs); the overall response rate was 58.4% (3036 questionnaires returned, of which 3004 were analyzable). Sampling strata were based on College of Family Physicians of Canada (CFPC) membership status and regions of Canada.ResultsClinical workload varied considerably across the demographic categories studied. Male physicians reported 8.9 more total weekly work hours than female physicians, but the mean number of medical and clinical services offered did not differ between the sexes. Solo practitioners reported 53.8 (95% confidence interval [CI] 52.7–55.0) total weekly work hours, whereas those practising in multidisciplinary clinics reported 45.0 (95% CI 43.2–46.8) hours. FP/GPs in the Atlantic and Prairie provinces reported 5.6 and 5.1 more weekly work hours, respectively, than the national average of 51.4 (95% CI 50.8–52.0) hours. Finally, FP/GPs who served inner-city populations reported 48.6 (95% CI 46.8–50.5) total weekly work hours, whereas those serving rural populations reported 57.0 (95% CI 54.7–59.2) hours. Mean weekly work hours were similar for all age cohorts less than 65 years. FP/GPs practising in less populated provinces and in rural areas reported the highest numbers of work hours, medical services offered and clinical procedures performed. InterpretationThese data suggest significant variations in FP/GP clinical workload in relation to key demographic variables. Physician resource planning in Canada is a challenging and inexact science. Past attempts have resulted in variable estimates of the ultimate need for physician services. There is a clear recognition that we need more information than simple head counts of physicians. We need to know, for example, what physicians do and how they work with other physicians, and we need to identify regional variations and differences in practice patterns.Past studies of family physician practice patterns have measured workload in terms of hours worked,1,2,3 number of patient visits,2,3 billings to health insurance plans4,5 and range of clinical procedures performed.5,6,7 These outcomes have been analyzed in relation to practice setting,1,2,6,7 geographic physician density,4,5 sex,1,2,3,4,5,6,7 age,1,2,4,5,7 years in practice3,6 and type of practice.1,2,3,6,7Although past studies have proven useful in describing the significant relations that exist between physician workloads and demographic characteristics, they have not addressed the broader issue of access to family physicians'' services throughout Canada. By gathering uniform information from family doctors across the country, the College of Family Physicians of Canada (CFPC) National Family Physician Survey (NFPS) addresses this information gap. In this report we present the results of the 1997/98 NFPS, describing physician workload measures in relation to a comprehensive set of demographic variables. 相似文献
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Background
Assessing marijuana''s impact on intelligence quotient (IQ) has been hampered by a lack of evaluation of subjects before they begin to use this substance. Using data from a group of young people whom we have been following since birth, we examined IQ scores before, during and after cessation of regular marijuana use to determine any impact of the drug on this measure of cognitive function.Methods
We determined marijuana use for seventy 17- to 20-year-olds through self-reporting and urinalysis. IQ difference scores were calculated by subtracting each person''s IQ score at 9–12 years (before initiation of drug use) from his or her score at 17–20 years. We then compared the difference in IQ scores of current heavy users (at least 5 joints per week), current light users (less than 5 joints per week), former users (who had not smoked regularly for at least 3 months) and non-users (who never smoked more than once per week and no smoking in the past two weeks).Results
Current marijuana use was significantly correlated (p < 0.05) in a dose- related fashion with a decline in IQ over the ages studied. The comparison of the IQ difference scores showed an average decrease of 4.1 points in current heavy users (p < 0.05) compared to gains in IQ points for light current users (5.8), former users (3.5) and non-users (2.6).Interpretation
Current marijuana use had a negative effect on global IQ score only in subjects who smoked 5 or more joints per week. A negative effect was not observed among subjects who had previously been heavy users but were no longer using the substance. We conclude that marijuana does not have a long-term negative impact on global intelligence. Whether the absence of a residual marijuana effect would also be evident in more specific cognitive domains such as memory and attention remains to be ascertained.Marijuana produces well-documented, acute cognitive changes that last for several hours after the drug has been ingested.1,2,3 Whether it produces cognitive dysfunction beyond this period of acute intoxication is much more difficult to establish. Approaches to investigating long-lasting effects include clinical assessment of long-term users,4,5,6 observations of subcultures in countries where long-term daily use of cannabis has been the cultural norm for decades7,8,9 and marijuana administration studies in which subjects with a history of use ranging from infrequent to extensive are given the drug in controlled laboratory settings after various periods of abstinence.10,11,12 As discussed in several reviews of the literature,1,13,14 the findings have been equivocal.Most studies that examined heavy marijuana users for possible cognitive dysfunction lasting beyond the acute intoxication period assessed subjects after an abstinence period of only a day or two.10,12,15,16 The fact that cannabinoid metabolites have been detected in the urine of long-term marijuana users after weeks or even months of abstinence17,18,19 compromises the interpretation of these studies. To account for potential pre-existing differences between users and non-users, studies have typically matched the comparison group with the user group in terms of non-marijuana variables.6,20 Suggestions for improving study designs13,14 have emphasized both the need for comparison groups to be as similar as possible to the drug-using group and the need for a prolonged abstinence period. The most desirable procedure would involve a longitudinal, prospective design in which cognitive measures were available for all non-using and using subjects before and after marijuana consumption had been initiated by the users.15The Ottawa Prenatal Prospective Study (OPPS), underway since 1978, satisfies these criteria. This study permits both within-subject and between-subject comparisons among relatively low-risk non-users and users before, during and after quitting regular marijuana use. The primary objective of the OPPS is the neuropsychologic assessment of children exposed prenatally to marijuana or cigarettes. Women who used and did not use marijuana and cigarettes volunteered to participate during their pregnancy, and their children, now between the ages of 17 and 20 years, have been assessed since birth. Details of the recruitment of the largely middle-class families, the assessment procedures and the findings for the children from birth to adolescence have been summarized elsewhere.21,22The objectives of the current study were as follows: to determine if current, regular marijuana use is predictive of decline in IQ from pre-usage levels, to determine if a differential effect on IQ occurs with heavy versus light current, regular marijuana use, and to determine if any IQ effects persist after subjects cease using marijuana for at least 3 months. 相似文献5.
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Carolyn A. Emery J. David Cassidy Terry P. Klassen Rhonda J. Rosychuk Brian H. Rowe 《CMAJ》2005,172(6):749-754
Background
Sport is the leading cause of injury requiring medical attention among adolescents. We studied the effectiveness of a home-based balance-training program using a wobble board in improving static and dynamic balance and reducing sports-related injuries among healthy adolescents.Methods
In this cluster randomized controlled trial, we randomly selected 10 of 15 high schools in Calgary to participate in the fall of 2001. We then recruited students from physical education classes and randomly assigned them, by school, to either the intervention (n = 66) or the control (n = 61) group. Students in the intervention group participated in a daily 6-week and then a weekly 6-month home-based balance-training program using a wobble board. Students at the control schools received testing only. The primary outcome measures were timed static and dynamic balance, 20-m shuttle run and vertical jump, which were measured at baseline and biweekly for 6 weeks. Self-reported injury data were collected over the 6-month follow-up period.Results
At 6 weeks, improvements in static and dynamic balance were observed in the intervention group but not in the control group (difference in static balance 20.7 seconds, 95% confidence interval [CI] 10.8 to 30.6 seconds; difference in dynamic balance 2.3 seconds, 95% CI 0.7 to 4.0 seconds). There was evidence of a protective effect of balance training in over 6 months (relative risk of injury 0.2, 95% CI 0.05 to 0.88). The number needed to treat to avoid 1 injury over 6 months was 8 (95% CI 4 to 35).Interpretation
Balance training using a wobble board is effective in improving static and dynamic balance and reducing sports-related injuries among healthy adolescents.Adolescents commonly participate in sports.1,2 In a survey of adolescents in Alberta, 59% reported that they took part in sports more than 5 hours per week (unpublished data). In North America, sport is the leading cause of injury requiring medical attention and visits to an emergency department among adolescents.3,4 In Alberta 26% of youths aged 15–19 years in a survey reported sustaining a sports-related injury requiring medical attention.5 The impact may be lifelong, as there is evidence that knee and ankle injuries may result in an increased risk of osteoarthritis later in life.6,7,8 In addition, each year 8% of adolescents drop out of sports activities because of injury.9 The reduction in physical activity resulting from sports-related injuries could have significant long-term effects on morbidity and mortality.10,11Proprioceptive balance training is used in rehabilitation following sports-related injuries and is becoming recognized as an important element in injury prevention in sports.12,13,14,15,16,17,18,19 Running, jumping or pivoting on one leg relies on a sense of joint position and muscular control for joint stability. There is evidence that static balance improves following proprioceptive balance training using a wobble board.20,21,22,23 However, most of these studies did not examine the effect of dynamic proprioceptive balance training, which may improve postural control in athletic situations and prevent some injuries.There is evidence from randomized trials that multifaceted prevention programs, including proprioceptive balance training using a wobble board, are effective in reducing injuries to the lower extremities in specific sports.12,13,14,15,16,17,18,19 However, the programs in these trials were multifaceted (i.e., included warm-up, flexibility, jump training, strength training, rehabilitation and sport-specific technical components), and balance was not measured. The effectiveness of balance training alone on balance ability and prevention of injury remains unclear. Moreover, the use of these techniques in adolescents and non-elite athletes has not been studied.The objectives of our study were to determine the effectiveness of a proprioceptive home-based balance-training program in improving static and dynamic balance in adolescents and to examine the effectiveness of this training program on reducing sports-related injury among adolescents. 相似文献8.
Hong-Yu Wang Gary W.K. Wong Yu-Zhi Chen Alexander C. Ferguson Justina M. Greene Yu Ma Nan-Shan Zhong Christopher K.W. Lai Malcolm R. Sears 《CMAJ》2008,179(11):1133-1142
Background
Studies of the prevalence of asthma among migrating populations may help in identifying environmental risk factors.Methods
We analyzed data from Vancouver, Canada, and from Guangzhou, Beijing and Hong Kong, China, collected during phase 3 of the International Study of Asthma and Allergies in Childhood. We subdivided the Vancouver adolescents according to whether they were Chinese immigrants to Canada, Canadian-born Chinese or Canadian-born non-Chinese. We compared the prevalence of asthma and wheezing among Chinese adolescents born in Canada, Chinese adolescents who had immigrated to Canada and Chinese adolescents living in China.Results
Of 7794 Chinese adolescents who met the inclusion criteria, 3058 were from Guangzhou, 2824 were from Beijing, and 1912 were from Hong Kong. Of 2235 adolescents in Vancouver, Canada, 475 were Chinese immigrants, 617 were Canadian-born Chinese, and 1143 were Canadian-born non-Chinese. The prevalence of current wheezing among boys ranged from 5.9% in Guangzhou to 11.2% in Canadian-born Chinese adolescents. For girls, the range was 4.3% in Guangzhou to 9.8% in Canadian-born Chinese adolescents. The prevalence of ever having had asthma ranged from 6.6% to 16.6% for boys and from 2.9% to 15.0% for girls. Prevalence gradients persisted after adjustment for other environmental variables (odds ratios for ever having had asthma among Canadian-born Chinese compared with native Chinese in Guangzhou: 2.72 [95% confidence interval 1.75–4.23] for boys and 5.50 [95% confidence interval 3.21–9.44] for girls; p < 0.001 for both). Among Chinese adolescents living in Vancouver, the prevalence of ever wheezing increased with duration of residence, from 14.5% among those living in Canada for less than 7 years to 20.9% among those living their entire life in Canada. The same pattern was observed for the prevalence of ever having had asthma, from 7.7% to 15.9%.Interpretation
Asthma symptoms in Chinese adolescents were lowest among residents of mainland China, were greater for those in Hong Kong and those who had immigrated to Canada, and were highest among those born in Canada. These findings suggest that environmental factors and duration of exposure influence asthma prevalence.The prevalence of asthma symptoms exhibits large geographic variations, even among genetically similar groups,1,2 which suggests that differences may reflect variation in environmental factors. Epidemiologic studies have demonstrated associations between asthma and exposure to household allergens,3 pets,4 environmental tobacco smoke5 and environmental pollution,6 as well as sex,7 obesity,8 number of siblings and birth order,9 and maternal education.10 Increasing “westernization” of environmental factors (such as changes in maternal diet, smaller family size, fewer infections during infancy, increased use of antibiotics and vaccination, less exposure to rural environments and improved sanitation) has been associated with an increased risk of childhood asthma.11 Conversely, the hygiene hypothesis proposed by Strachan in 1989 suggested that infections and contact with older siblings may reduce the risk of allergic diseases.12Migration studies examining children of the same ethnic background living in different environments for part or all of their lives may help to identify factors relevant to the development of diseases and may explain some of the observed geographic variations in prevalence. In the International Study of Asthma and Allergies in Childhood, prevalence rates for asthma in Canada were among the highest in the world, whereas those in China were among the lowest.2 This difference could reflect genetic or environmental factors. China has been and continues to be a major source of international migration.13,14 Of immigrants in Vancouver, Canada, who landed between 1985 and 2001, half were born in East Asia, mainly Hong Kong and mainland China.15 Few studies on the prevalence of asthma among immigrants have been undertaken in Canada,16 and data for Chinese people living in Canada are not available.We hypothesized that the prevalence of asthma would be highest among Canadian-born Chinese adolescents, lower among Chinese adolescents who had immigrated to Canada and lowest among Chinese adolescents living in China. We further hypothesized that, among Chinese immigrants to Canada, prevalence rates of asthma would relate to duration of residence in Canada. 相似文献9.
William A. Fisher Sukhbir S. Singh Paul A. Shuper Mark Carey Felicia Otchet Deborah MacLean-Brine Diane Dal Bello Jennifer Gunter 《CMAJ》2005,172(5):637-641
Background
Although repeat induced abortion is common, data concerning characteristics of women undergoing this procedure are lacking. We conducted this study to identify the characteristics, including history of physical abuse by a male partner and history of sexual abuse, of women who present for repeat induced abortion.Methods
We surveyed a consecutive series of women presenting for initial or repeat pregnancy termination to a regional provider of abortion services for a wide geographic area in southwestern Ontario between August 1998 and May 1999. Self-reported demographic characteristics, attitudes and practices regarding contraception, history of relationship violence, history of sexual abuse or coercion, and related variables were assessed as potential correlates of repeat induced abortion. We used χ2 tests for linear trend to examine characteristics of women undergoing a first, second, or third or subsequent abortion. We analyzed significant correlates of repeat abortion using stepwise multivariate multinomial logistic regression to identify factors uniquely associated with repeat abortion.Results
Of the 1221 women approached, 1145 (93.8%) consented to participate. Data regarding first versus repeat abortion were available for 1127 women. A total of 68.2%, 23.1% and 8.7% of the women were seeking a first, second, or third or subsequent abortion respectively. Adjusted odds ratios for undergoing repeat versus a first abortion increased significantly with increased age (second abortion: 1.08, 95% confidence interval [CI] 1.04–1.09; third or subsequent abortion: 1.11, 95% CI 1.07–1.15), oral contraceptive use at the time of conception (second abortion: 2.17, 95% CI 1.52–3.09; third or subsequent abortion: 2.60, 95% CI 1.51–4.46), history of physical abuse by a male partner (second abortion: 2.04, 95% CI 1.39–3.01; third or subsequent abortion: 2.78, 95% CI 1.62–4.79), history of sexual abuse or violence (second abortion: 1.58, 95% CI 1.11–2.25; third or subsequent abortion: 2.53, 95% CI 1.50–4.28), history of sexually transmitted disease (second abortion: 1.50, 95% CI 0.98–2.29; third or subsequent abortion: 2.26, 95% CI 1.28–4.02) and being born outside Canada (second abortion: 1.83, 95% CI 1.19–2.79; third or subsequent abortion: 1.75, 95% CI 0.90–3.41).Interpretation
Among other factors, a history of physical or sexual abuse was associated with repeat induced abortion. Presentation for repeat abortion may be an important indication to screen for a current or past history of relationship violence and sexual abuse.Repeat pregnancy termination procedures are common in Canada (where 35.5% of all induced abortions are repeat procedures)1,2 and the United States (where 48% of induced abortions are repeat procedures).3,4,5,6,7 Rates of repeat induced abortion increased in both countries for an initial period after abortion was legalized, as a result of an increase in the number of women who had access to a first, and consequently to repeat, legal induced abortion.1,6,8,9 At present, rates of initial and repeat abortion in Canada and the United States appear to be stabilizing.2,7Research concerning characteristics of women who undergo repeat induced abortions has been limited in scope. In a literature search we identified fewer than 20 studies in this area published over the past 3 decades. However, available research has shown several consistent findings. Women undergoing repeat abortions are more likely than those undergoing a first abortion to report using a method of contraception at the time of conception.7,8,10,11 In addition, women seeking repeat abortions report more challenging family situations than women seeking initial abortions: they are more likely to be separated, divorced, widowed or living in a common-law marriage, and to report difficulties with their male partner.1,5,8,11,12 They also are older,7,13 have more children1,5,13 and are more often non-white7,11,13 than women seeking initial abortions.There is little evidence to suggest that women seeking repeat abortion are using pregnancy termination as a method of birth control.1,5,6,8,11 Evidence also does not indicate that women seeking repeat abortion are psychologically maladjusted.8,13Our literature review showed that many studies of repeat abortion are 20 to 30 years old and are based on data collected when abortion was a newly legalized procedure.5,11 Furthermore, in studies of correlates of repeat abortion the investigators did not examine a range of personality characteristics that are known to influence women''s reproductive health outcomes,14,15 including attitudes about sexuality,14 health locus of control,16,17 degree of social integration,16 attitudes about contraception18,19 and history of sexual or physical abuse.20,21,22 The objective of the current study was to identify characteristics of women who undergo repeat induced abortion. 相似文献10.
Ching Leang Xinlei Qian Tünde Mester Derek R. Lovley 《Applied and environmental microbiology》2010,76(12):4080-4084
Immunogold localization revealed that OmcS, a cytochrome that is required for Fe(III) oxide reduction by Geobacter sulfurreducens, was localized along the pili. The apparent spacing between OmcS molecules suggests that OmcS facilitates electron transfer from pili to Fe(III) oxides rather than promoting electron conduction along the length of the pili.There are multiple competing/complementary models for extracellular electron transfer in Fe(III)- and electrode-reducing microorganisms (8, 18, 20, 44). Which mechanisms prevail in different microorganisms or environmental conditions may greatly influence which microorganisms compete most successfully in sedimentary environments or on the surfaces of electrodes and can impact practical decisions on the best strategies to promote Fe(III) reduction for bioremediation applications (18, 19) or to enhance the power output of microbial fuel cells (18, 21).The three most commonly considered mechanisms for electron transfer to extracellular electron acceptors are (i) direct contact between redox-active proteins on the outer surfaces of the cells and the electron acceptor, (ii) electron transfer via soluble electron shuttling molecules, and (iii) the conduction of electrons along pili or other filamentous structures. Evidence for the first mechanism includes the necessity for direct cell-Fe(III) oxide contact in Geobacter species (34) and the finding that intensively studied Fe(III)- and electrode-reducing microorganisms, such as Geobacter sulfurreducens and Shewanella oneidensis MR-1, display redox-active proteins on their outer cell surfaces that could have access to extracellular electron acceptors (1, 2, 12, 15, 27, 28, 31-33). Deletion of the genes for these proteins often inhibits Fe(III) reduction (1, 4, 7, 15, 17, 28, 40) and electron transfer to electrodes (5, 7, 11, 33). In some instances, these proteins have been purified and shown to have the capacity to reduce Fe(III) and other potential electron acceptors in vitro (10, 13, 29, 38, 42, 43, 48, 49).Evidence for the second mechanism includes the ability of some microorganisms to reduce Fe(III) that they cannot directly contact, which can be associated with the accumulation of soluble substances that can promote electron shuttling (17, 22, 26, 35, 36, 47). In microbial fuel cell studies, an abundance of planktonic cells and/or the loss of current-producing capacity when the medium is replaced is consistent with the presence of an electron shuttle (3, 14, 26). Furthermore, a soluble electron shuttle is the most likely explanation for the electrochemical signatures of some microorganisms growing on an electrode surface (26, 46).Evidence for the third mechanism is more circumstantial (19). Filaments that have conductive properties have been identified in Shewanella (7) and Geobacter (41) species. To date, conductance has been measured only across the diameter of the filaments, not along the length. The evidence that the conductive filaments were involved in extracellular electron transfer in Shewanella was the finding that deletion of the genes for the c-type cytochromes OmcA and MtrC, which are necessary for extracellular electron transfer, resulted in nonconductive filaments, suggesting that the cytochromes were associated with the filaments (7). However, subsequent studies specifically designed to localize these cytochromes revealed that, although the cytochromes were extracellular, they were attached to the cells or in the exopolymeric matrix and not aligned along the pili (24, 25, 30, 40, 43). Subsequent reviews of electron transfer to Fe(III) in Shewanella oneidensis (44, 45) appear to have dropped the nanowire concept and focused on the first and second mechanisms.Geobacter sulfurreducens has a number of c-type cytochromes (15, 28) and multicopper proteins (12, 27) that have been demonstrated or proposed to be on the outer cell surface and are essential for extracellular electron transfer. Immunolocalization and proteolysis studies demonstrated that the cytochrome OmcB, which is essential for optimal Fe(III) reduction (15) and highly expressed during growth on electrodes (33), is embedded in the outer membrane (39), whereas the multicopper protein OmpB, which is also required for Fe(III) oxide reduction (27), is exposed on the outer cell surface (39).OmcS is one of the most abundant cytochromes that can readily be sheared from the outer surfaces of G. sulfurreducens cells (28). It is essential for the reduction of Fe(III) oxide (28) and for electron transfer to electrodes under some conditions (11). Therefore, the localization of this important protein was further investigated. 相似文献
11.
Paola Sette Joshua A. Jadwin Vincent Dussupt Nana F. Bello Fadila Bouamr 《Journal of virology》2010,84(16):8181-8192
The p6 region of HIV-1 Gag contains two late (L) domains, PTAP and LYPXnL, that bind Tsg101 and Alix, respectively. Interactions with these two cellular proteins recruit members of the host''s fission machinery (ESCRT) to facilitate HIV-1 release. Other retroviruses gain access to the host ESCRT components by utilizing a PPXY-type L domain that interacts with cellular Nedd4-like ubiquitin ligases. Despite the absence of a PPXY motif in HIV-1 Gag, interaction with the ubiquitin ligase Nedd4-2 was recently shown to stimulate HIV-1 release. We show here that another Nedd4-like ubiquitin ligase, Nedd4-1, corrected release defects resulting from the disruption of PTAP (PTAP−), suggesting that HIV-1 Gag also recruits Nedd4-1 to facilitate virus release. Notably, Nedd4-1 remediation of HIV-1 PTAP− budding defects is independent of cellular Tsg101, implying that Nedd4-1''s function in HIV-1 release does not involve ESCRT-I components and is therefore distinct from that of Nedd4-2. Consistent with this finding, deletion of the p6 region decreased Nedd4-1-Gag interaction, and disruption of the LYPXnL motif eliminated Nedd4-1-mediated restoration of HIV-1 PTAP−. This result indicated that both Nedd4-1 interaction with Gag and function in virus release occur through the Alix-binding LYPXnL motif. Mutations of basic residues located in the NC domain of Gag that are critical for Alix''s facilitation of HIV-1 release, also disrupted release mediated by Nedd4-1, further confirming a Nedd4-1-Alix functional interdependence. In fact we found that Nedd4-1 binds Alix in both immunoprecipitation and yeast-two-hybrid assays. In addition, Nedd4-1 requires its catalytic activity to promote virus release. Remarkably, RNAi knockdown of cellular Nedd4-1 eliminated Alix ubiquitination in the cell and impeded its ability to function in HIV-1 release. Together our data support a model in which Alix recruits Nedd4-1 to facilitate HIV-1 release mediated through the LYPXnL/Alix budding pathway via a mechanism that involves Alix ubiquitination.Retroviral Gag polyproteins bear short conserved sequences that control virus budding and release. As such, these motifs have been dubbed late or L domains (49). Three types of L domains have thus far been characterized: PT/SAP, LYPXnL, and PPPY motifs (5, 9, 32). They recruit host proteins known to function in the vacuolar protein sorting (vps) of cargo proteins and the generation of multivesicular bodies (MVB) compartments (2). It is currently accepted that budding of vesicles into MVB involves the sequential recruitment of endosomal sorting complexes required for transport (ESCRT-I, -II, and -III) and the activity of the VPS4 AAA-ATPase (22). These sorting events are believed to be triggered by recognition of ubiquitin molecules conjugated to cargo proteins (20, 24, 41). For retrovirus budding, L domain motifs are the primary signals in Gag that elicit the recruitment of ESCRT components to facilitate viral budding. Consequently, mutations in L domain motifs or dominant-negative interference with the function of ESCRT-III members or the VPS4 ATPase adversely affect virus release. This indicates that Gag interactions with the ESCRT machinery are necessary for virus budding and separation from the cell (7, 10, 15, 16, 21, 28, 44).Two late domains have been identified within the p6 region of human immunodeficiency virus type 1 (HIV-1) Gag protein: the PTAP and LYPXnL motifs. The PTAP motif binds the cellular protein Tsg101 (15, 39, 40, 47), whereas the LYPXnL motif is the docking site for Alix (44). Tsg101 functions in HIV-1 budding (15) as a member of ESCRT-I (30, 48), a soluble complex required for the generation of MVB. This process is topologically similar to HIV-1 budding and requires the recruitment of ESCRT-III members called the charged-multivesicular body proteins (3, 29, 48) and the activity of the VPS4 AAA-ATPase (4, 48). In addition to binding the LYPXnL motif, Alix also interacts with the nucleocapsid (NC) domain of HIV-1 Gag (13, 38), thus linking Gag to components of ESCRT-III that are critical for virus release (13).Other retroviruses, including the human T-cell leukemia virus (HTLV) and the Moloney murine leukemia virus (MoMLV), utilize the PPPY-type L domain to efficiently release virus (7, 26, 51). The PPPY motif binds members of the Nedd4-like ubiquitin ligase family (6, 7, 16, 19, 25, 43), whose normal cellular function is to ubiquitinate cargo proteins and target them into the MVB sorting pathway (11, 12, 20). Members of the Nedd4-like ubiquitin ligase family include Nedd4-1, Nedd4-2 (also known as Nedd4L), WWP-1/2, and Itch. They contain three distinct domains: an N-terminal membrane binding C2 domain (12), a central PPPY-interacting WW domain (43), and a C-terminal HECT domain that contains the ubiquitin ligase active site (42). The functional requirement for the binding of Nedd4-like ubiquitin ligases to the PPPY motif in virus budding has been demonstrated (7, 16, 18, 19, 25, 26, 28, 50, 51). Overexpression of dominant-negative mutants of Nedd4-like ligases, ESCRT-III components, or VPS4 cause a potent inhibition of PPPY-dependent virus release (7, 19, 29, 31, 52) and induce assembly and budding defects similar to those observed after perturbation of the PPPY motif (26, 51). These observations demonstrated that Nedd4-like ligases connect Gag encoding PPPY motif to ESCRT-III and VPS4 proteins to facilitate virus release.Whereas the role of Nedd4-like ubiquitin ligases in virus budding has been established, the protein interactions that link them to the cell''s ESCRT-III pathway are still unknown. Evidence for associations of Nedd4-like ligases with ESCRT proteins have been previously reported and include: the binding of Nedd4-like ubiquitin ligases LD1 and Nedd4-1 to ESCRT-I member Tsg101 (6, 31), the colocalization of multiple Nedd4-like ubiquitin ligases with endosomal compartments (1, 28), the requirement of the cell''s ESCRT pathway for Itch mediated L domain independent stimulation of MoMLV release (23), and the ubiquitination of ESCRT-I components with a shorter isoform, Nedd4-2s (8). Therefore, Nedd4-like ubiquitin ligase interactions with members of the cell''s ESCRT pathway may provide retroviral Gag with access to the host budding machinery required for virus release.Although HIV-1 Gag does not carry the PPPY canonical sequence known to interact with Nedd4-like ubiquitin ligases, both Nedd4-1 and Nedd4-2 were shown to restore the release of the HIV-1 PTAP− mutant, albeit Nedd4-1 with less efficiency than Nedd4-2 (8, 46). These findings suggested that HIV-1 might utilize cellular Nedd4-like ubiquitin ligases to increase virus release. We present here evidence demonstrating that Nedd4-1 interacts with Gag and enhances HIV-1 PTAP− virus release. Furthermore, we show that Nedd4-1''s function in HIV-1 release is distinct from that of Nedd4-2 in both its viral and cellular requirements. Notably, we found that Nedd4-1 enhancement of HIV-1 release requires the Alix-binding LYPXnL L domain motif in the p6 region and basic residues in the NC domain. In addition, Alix''s facilitation of HIV-1 release requires cellular Nedd4-1, since mutations in NC that prevented Alix-mediated HIV-1 release also eliminated release by overexpression of Nedd4-1. This suggested a Nedd4-1-Alix physical and functional interdependence. In agreement with this, we found Nedd4-1 to bind and ubiquitinate Alix in the cell. Taken together, these results support a model in which Alix recruits Nedd4-1 to facilitate late steps of HIV-1 release through the LYPXnL L domain motif via a mechanism that involves Alix ubiquitination. 相似文献
12.
13.
Timothy P. Brennan John O. Woods Ahmad R. Sedaghat Janet D. Siliciano Robert F. Siliciano Claus O. Wilke 《Journal of virology》2009,83(17):8470-8481
Highly active antiretroviral therapy (HAART) can reduce human immunodeficiency virus type 1 (HIV-1) viremia to clinically undetectable levels. Despite this dramatic reduction, some virus is present in the blood. In addition, a long-lived latent reservoir for HIV-1 exists in resting memory CD4+ T cells. This reservoir is believed to be a source of the residual viremia and is the focus of eradication efforts. Here, we use two measures of population structure—analysis of molecular variance and the Slatkin-Maddison test—to demonstrate that the residual viremia is genetically distinct from proviruses in resting CD4+ T cells but that proviruses in resting and activated CD4+ T cells belong to a single population. Residual viremia is genetically distinct from proviruses in activated CD4+ T cells, monocytes, and unfractionated peripheral blood mononuclear cells. The finding that some of the residual viremia in patients on HAART stems from an unidentified cellular source other than CD4+ T cells has implications for eradication efforts.Successful treatment of human immunodeficiency virus type 1 (HIV-1) infection with highly active antiretroviral therapy (HAART) reduces free virus in the blood to levels undetectable by the most sensitive clinical assays (18, 36). However, HIV-1 persists as a latent provirus in resting, memory CD4+ T lymphocytes (6, 9, 12, 16, 48) and perhaps in other cell types (45, 52). The latent reservoir in resting CD4+ T cells represents a barrier to eradication because of its long half-life (15, 37, 40-42) and because specifically targeting and purging this reservoir is inherently difficult (8, 25, 27).In addition to the latent reservoir in resting CD4+ T cells, patients on HAART also have a low amount of free virus in the plasma, typically at levels below the limit of detection of current clinical assays (13, 19, 35, 37). Because free virus has a short half-life (20, 47), residual viremia is indicative of active virus production. The continued presence of free virus in the plasma of patients on HAART indicates either ongoing replication (10, 13, 17, 19), release of virus after reactivation of latently infected CD4+ T cells (22, 24, 31, 50), release from other cellular reservoirs (7, 45, 52), or some combination of these mechanisms. Finding the cellular source of residual viremia is important because it will identify the cells that are still capable of producing virus in patients on HAART, cells that must be targeted in any eradication effort.Detailed analysis of this residual viremia has been hindered by technical challenges involved in working with very low concentrations of virus (13, 19, 35). Recently, new insights into the nature of residual viremia have been obtained through intensive patient sampling and enhanced ultrasensitive sequencing methods (1). In a subset of patients, most of the residual viremia consisted of a small number of viral clones (1, 46) produced by a cell type severely underrepresented in the peripheral circulation (1). These unique viral clones, termed predominant plasma clones (PPCs), persist unchanged for extended periods of time (1). The persistence of PPCs indicates that in some patients there may be another major cellular source of residual viremia (1). However, PPCs were observed in a small group of patients who started HAART with very low CD4 counts, and it has been unclear whether the PPC phenomenon extends beyond this group of patients. More importantly, it has been unclear whether the residual viremia generally consists of distinct virus populations produced by different cell types.Since the HIV-1 infection in most patients is initially established by a single viral clone (23, 51), with subsequent diversification (29), the presence of genetically distinct populations of virus in a single individual can reflect entry of viruses into compartments where replication occurs with limited subsequent intercompartmental mixing (32). Sophisticated genetic tests can detect such population structure in a sample of viral sequences (4, 39, 49). Using two complementary tests of population structure (14, 43), we analyzed viral sequences from multiple sources within individual patients in order to determine whether a source other than circulating resting CD4+ T cells contributes to residual viremia and viral persistence. Our results have important clinical implications for understanding HIV-1 persistence and treatment failure and for improving eradication strategies, which are currently focusing only on the latent CD4+ T-cell reservoir. 相似文献
14.
Ronald A. Shikiya Jacob I. Ayers Charles R. Schutt Anthony E. Kincaid Jason C. Bartz 《Journal of virology》2010,84(11):5706-5714
Prion strain interference can influence the emergence of a dominant strain from a mixture; however, the mechanisms underlying prion strain interference are poorly understood. In our model of strain interference, inoculation of the sciatic nerve with the drowsy (DY) strain of the transmissible mink encephalopathy (TME) agent prior to superinfection with the hyper (HY) strain of TME can completely block HY TME from causing disease. We show here that the deposition of PrPSc, in the absence of neuronal loss or spongiform change, in the central nervous system corresponds with the ability of DY TME to block HY TME infection. This suggests that DY TME agent-induced damage is not responsible for strain interference but rather prions compete for a cellular resource. We show that protein misfolding cyclic amplification (PMCA) of DY and HY TME maintains the strain-specific properties of PrPSc and replicates infectious agent and that DY TME can interfere, or completely block, the emergence of HY TME. DY PrPSc does not convert all of the available PrPC to PrPSc in PMCA, suggesting the mechanism of prion strain interference is due to the sequestering of PrPC and/or other cellular components required for prion conversion. The emergence of HY TME in PMCA was controlled by the initial ratio of the TME agents. A higher ratio of DY to HY TME agent is required for complete blockage of HY TME in PMCA compared to several previous in vivo studies, suggesting that HY TME persists in animals coinfected with the two strains. This was confirmed by PMCA detection of HY PrPSc in animals where DY TME had completely blocked HY TME from causing disease.Prions are infectious agents of animals, including humans, which are comprised of PrPSc, a misfolded isoform of the noninfectious host encoded protein PrPC (17, 24, 50, 63). Prion diseases of humans are unique neurodegenerative disorders in that they can have either a sporadic, familial, or infectious etiology. Prions cause disease in economically important domestic and wild animal species such as bovine spongiform encephalopathy in cattle and chronic wasting disease in wild and captive cervids (20, 62). Prion diseases can be zoonotic as illustrated by the transmission of bovine spongiform encephalopathy to humans that resulted in the emergence of variant Creutzfeldt-Jacob disease (14, 19, 22, 23, 46, 61, 68). Prion diseases are inevitably fatal and there are currently no effective treatments (21).Prion strains are defined by a characteristic set of features that breed true upon experimental passage (33, 34). Strain-specific differences have been identified in incubation period, clinical signs, agent distribution, overdominance, host range, neuropathology, and biochemical properties of PrPSc (5, 10, 11, 13, 28, 34, 42, 44). Strain-specific conformations of PrPSc are hypothesized to encode prion strain diversity; however, it is not understood how these differences result in the distinct strain properties (11, 19, 40, 47, 59, 66).Prion strain interference may be involved in the emergence of a dominant strain from a mixture as could occur during prion adaptation to a new host species or during prion evolution (4, 36, 43, 48, 56). In the natural prion diseases, there are examples where an individual host may be infected with more than one prion strain (15, 25, 55, 57, 58). Experimentally, coinfection or superinfection of prion strains can result in interference where a blocking, long incubation period strain extends the incubation period or completely blocks a superinfecting, short incubation period strain from causing disease (26, 27). Prion interference has been described in experimental studies of mice and hamsters infected with a wide variety of prion strains and routes of inoculation, suggesting it may be a common property of prion disease (3, 27, 52, 53, 60).It has been proposed that prion strains compete for a shared “replication site”; however, mechanistic details are not known, and it is unclear whether the blocking strain destroys or occupies the replication sites required for the superinfecting strain (28). The transport to and relative onset of replication of interfering strains in a common population of neurons is an important factor that can determine which strain will emerge (8). In the present study, we sought to determine whether the blocking strain disables transport and spread of the superinfecting strain or whether prion interference is due to competition for a cellular resource. 相似文献
15.
UNINTENTIONAL WEIGHT LOSS, or the involuntary decline in total body weight over time, is common among elderly people who live at home. Weight loss in elderly people can have a deleterious effect on the ability to function and on quality of life and is associated with an increase in mortality over a 12-month period. A variety of physical, psychological and social conditions, along with age-related changes, can lead to weight loss, but there may be no identifiable cause in up to one-quarter of patients. We review the incidence and prevalence of weight loss in elderly patients, its impact on morbidity and mortality, the common causes of unintentional weight loss and a clinical approach to diagnosis. Screening tools to detect malnutrition are highlighted, and nonpharmacologic and pharmacologic strategies to minimize or reverse weight loss in older adults are discussed.Unintentional weight loss is the involuntary decline in total body weight over time. In clinical practice, it is encountered in up to 8% of all adult outpatients1 and 27% of frail people 65 years and older.2 Weight loss is an important risk factor in elderly patients. It is associated with increased mortality, which can range from 9% to as high as 38% within 1 to 2.5 years after weight loss has occurred.1,3,4 Frail elderly people,5 people with low baseline body weight,5,6,7 and elderly patients recently admitted to hospital are particularly susceptible to increased mortality.8,9 Weight loss is also associated with an increased risk of in-hospital complications,10,11 a decline in activities of daily living or physical function,12,13 higher rates of admission to an institution2,8 and poorer quality of life.14 相似文献
16.
Yu-Wen Lin Kung-Chao Chang Chia-Min Kao Shih-Ping Chang Yuk-Ying Tung Shun-Hua Chen 《Journal of virology》2009,83(13):6477-6483
Enterovirus 71 (EV71) infects the central nervous system and causes death and long-term neurological sequelae in hundreds of thousands of young children, but its pathogenesis remains elusive. Immunopathological mechanisms have been suspected to contribute to the pathogenesis of neurological symptoms, so anti-inflammatory agents have been used to treat patients with neurological symptoms. The present study was therefore designed to investigate the functions of lymphocyte and antibody responses in EV71 infection using a mouse model. Immunohistochemical staining analysis revealed virus and three types of lymphocytes, B cells, CD4 T cells, and CD8 T cells, in the spinal cord of an EV71-infected patient who died. A study of mice showed that the levels of virus and lymphocytes in brains and antibody titers in sera were elevated during the time when the mice succumbed to death in a phenomenon analogous to that observed in patients. Further studies demonstrated that after infection, the disease severity, mortality, and tissue viral loads of mice deficient in B, CD4 T, or CD8 T cells were significantly higher than those of wild-type mice. In addition, treatment with a virus-specific antibody, but not a control antibody, before or after infection significantly reduced the disease severity, mortality, and tissue viral loads of mice deficient in B cells. Our results show that both lymphocyte and antibody responses protect mice from EV71 infection. Our study suggests the use of vaccines and virus-specific antibodies to control fatal outbreaks and raises caution over the use of corticosteroids to treat EV71-infected patients with neurological symptoms.Enterovirus 71 (EV71), a member of the family Picornaviridae, infects humans by the fecal-oral route and induces mild symptoms, such as herpangina and hand, foot and mouth disease. It can also infect the central nervous system (CNS) and induce fatal neurological manifestations, such as aseptic meningitis, brain stem encephalitis, encephalomyelitis, and acute flaccid paralysis, with cardiopulmonary complications, especially in young children. Most fatalities occur in cases with brain stem encephalitis and fulminant pulmonary edema complications (6, 7, 9, 12, 15, 19). Survivors of severe cases are often left with long-term neurologic sequelae (6, 14, 15).EV71 outbreaks have been reported periodically throughout the world (7, 9, 16). In the past decade, the Asia-Pacific region has experienced more frequent and widespread fatal outbreaks (16). The largest and most severe outbreak occurred in Taiwan in 1998 when 129,106 cases of herpangina and hand, foot and mouth disease, 405 cases of neurological and cardiopulmonary complications, and 78 deaths were reported (7). Since then, EV71 infection has become endemic in Taiwan and caused >40, >40, and 14 deaths in 2000, 2001, and 2008, respectively (3, 11). In addition, 42 deaths have been reported in China by June in 2008 (16). Although it has been estimated that EV71 infects millions of children and causes thousands of cases of neurologic sequelae and >200 deaths in the past decade (3, 7, 11, 16), there are no effective vaccines and specific antiviral therapies available to control fatal outbreaks due in part to the lack of understanding of viral pathogenesis.Infants and young children are very susceptible to EV71 infection. Immature immunity is therefore suspected to associate with increased morbidity and mortality (6, 7, 9). This is supported by the findings of lymphopenia, depletion of CD4 and CD8 T lymphocytes, and decreased cellular immunity in the peripheral blood of patients with brain stem encephalitis and pulmonary edema (4, 17). However, some clinical studies showed that elevated cellular immunity was linked with unfavorable outcomes (5, 8). High levels of white blood cell counts in blood and cerebrospinal fluid with a predominance of lymphocytes were detected in patients with fatal or severe sequelae (5, 8, 19, 22). In addition, autopsy reports revealed not only virus but also severe mononuclear cell infiltrates in the CNSs of patients who died (12, 22). Moreover, a clinical study reported that a patient developed opsomyoclonus syndrome, which is an autoimmune disease resulting from lesions in the dentate nucleus of the cerebellum (14). In this patient, the high titer of virus-specific antibodies detected at the onset of neurological disease and the responsiveness of the condition to anti-inflammatory agents (corticosteroids) provide further evidence of an autoimmune etiology. Besides corticosteroids, intravenous immunoglobulin (IVIG), which has several anti-inflammatory properties and often contains neutralizing antibodies to enteroviruses, has been a mandatory treatment for patients with neurological symptoms in Taiwan, because it has been shown to improve the conditions of patients infected with other enteroviruses, coxackievirus B, and echovirus (1, 5, 13, 18).Although corticosteroids have been used to treat EV71-infected patients with neurological symptoms (14, 15), the significance of lymphocyte and antibody responses in the pathogenesis of EV71 remains to be determined. The present study was therefore designed to address this issue using a mouse model. 相似文献
17.
18.
Momar Ndao Etienne Bandyayera Evelyne Kokoskin David Diemert Theresa W. Gyorkos J. Dick MacLean Ron St. John Brian J. Ward 《CMAJ》2005,172(1):46-50
Background
Imported malaria is an increasing problem. The arrival of 224 African refugees presented the opportunity to investigate the diagnosis and management of imported malaria within the Quebec health care system.Methods
The refugees were visited at home 3–4 months after arrival in Quebec. For 221, a questionnaire was completed and permission obtained for access to health records; a blood sample for malaria testing was obtained from 210.Results
Most of the 221 refugees (161 [73%]) had had at least 1 episode of malaria while in the refugee camps. Since arrival in Canada, 87 (39%) had had symptoms compatible with malaria for which medical care was sought. Complete or partial records were obtained for 66 of these refugees and for 2 asymptomatic adults whose children were found to have malaria: malaria had been appropriately investigated in 55 (81%); no malaria smear was requested for the other 13. Smears were reported as positive for 20 but confirmed for only 15 of the 55; appropriate therapy was verified for 10 of the 15. Of the 5 patients with a false-positive diagnosis of malaria, at least 3 received unnecessary therapy. Polymerase chain reaction testing of the blood sample obtained at the home visit revealed malaria parasites in 48 of the 210 refugees (23%; 95% confidence interval [CI] 17%– 29%). The rate of parasite detection was more than twice as high among the 19 refugees whose smears were reported as negative but not sent for confirmation (47%; 95% CI 25%– 71%).Interpretation
This study has demonstrated errors of both omission and commission in the response to refugees presenting with possible malaria. Smears were not consistently requested for patients whose presenting complaints were not “typical” of malaria, and a large proportion of smears read locally as “negative” were not sent for confirmation. Further effort is required to ensure optimal malaria diagnosis and care in such high-risk populations.In many industrialized countries, the incidence of imported malaria is rising because of changing immigration patterns and refugee policies as well as increased travel to malaria-endemic regions.1,2,3,4,5,6,7,8,9,10 Imported malaria is not rare in Canada (300–1000 cases per year),3 the United States2,3,4 or other industrialized countries.5,6,7,8,9,10 Malaria can be a serious challenge in these countries because of its potentially rapid and lethal course.11,12,13,14 The task of front-line health care providers is made particularly difficult by the protean clinical presentations of malaria. Classic periodic fevers (tertian or quartan) are seen infrequently.9,15,16,17,18,19 Atypical and subtle presentations are especially common in individuals who have partial immunity (e.g., immigrants and refugees from disease-endemic areas) or are taking malaria prophylaxis (e.g., travellers).9,16,17 Even when malaria is considered, an accurate diagnosis can remain elusive or can be delayed as a result of inadequate or distant specialized laboratory support.19,20In Quebec, the McGill University Centre for Tropical Diseases collaborates with the Laboratoire de santé publique du Québec to raise awareness of imported malaria, to offer training and quality-assurance testing, and to provide reference diagnostic services. A preliminary diagnosis is typically made by the local laboratory, and smears (with or without staining) are sent to the McGill centre, where they are reviewed within 2–48 hours, depending on the urgency of the request. Initial medical decisions are usually based on local findings and interpretations. Although malaria is a reportable disease, there is no requirement to use the reference service.On Aug. 9, 2000, 224 refugees from Tanzanian camps landed in Montréal aboard an airplane chartered by Canadian immigration authorities. Over the ensuing 5 weeks, the McGill University Centre for Tropical Diseases noted an increase in demand for malaria reference services and an apparent small “epidemic” of imported malaria. This “epidemic” prompted us to investigate the performance of the health care system in the diagnosis and management of imported malaria. 相似文献19.
Soil substrate membrane systems allow for microcultivation of fastidious soil bacteria as mixed microbial communities. We isolated established microcolonies from these membranes by using fluorescence viability staining and micromanipulation. This approach facilitated the recovery of diverse, novel isolates, including the recalcitrant bacterium Leifsonia xyli, a plant pathogen that has never been isolated outside the host.The majority of bacterial species have never been recovered in the laboratory (1, 14, 19, 24). In the last decade, novel cultivation approaches have successfully been used to recover “unculturables” from a diverse range of divisions (23, 25, 29). Most strategies have targeted marine environments (4, 23, 25, 32), but soil offers the potential for the investigation of vast numbers of undescribed species (20, 29). Rapid advances have been made toward culturing soil bacteria by reformulating and diluting traditional media, extending incubation times, and using alternative gelling agents (8, 21, 29).The soil substrate membrane system (SSMS) is a diffusion chamber approach that uses extracts from the soil of interest as the growth substrate, thereby mimicking the environment under investigation (12). The SSMS enriches for slow-growing oligophiles, a proportion of which are subsequently capable of growing on complex media (23, 25, 27, 30, 32). However, the SSMS results in mixed microbial communities, with the consequent difficulty in isolation of individual microcolonies for further characterization (10).Micromanipulation has been widely used for the isolation of specific cell morphotypes for downstream applications in molecular diagnostics or proteomics (5, 15). This simple technology offers the opportunity to select established microcolonies of a specific morphotype from the SSMS when combined with fluorescence visualization (3, 11). Here, we have combined the SSMS, fluorescence viability staining, and advanced micromanipulation for targeted isolation of viable, microcolony-forming soil bacteria. 相似文献
20.
Yi Liu Amanda Woodward Haiying Zhu Thomas Andrus John McNevin Jean Lee James I. Mullins Lawrence Corey M. Juliana McElrath Tuofu Zhu 《Journal of virology》2009,83(20):10821-10829
Understanding the mechanisms underlying potential altered susceptibility to human immunodeficiency virus type 1 (HIV-1) infection in highly exposed seronegative (ES) individuals and the later clinical consequences of breakthrough infection can provide insight into strategies to control HIV-1 with an effective vaccine. From our Seattle ES cohort, we identified one individual (LSC63) who seroconverted after over 2 years of repeated unprotected sexual contact with his HIV-1-infected partner (P63) and other sexual partners of unknown HIV-1 serostatus. The HIV-1 variants infecting LSC63 were genetically unrelated to those sequenced from P63. This may not be surprising, since viral load measurements in P63 were repeatedly below 50 copies/ml, making him an unlikely transmitter. However, broad HIV-1-specific cytotoxic T-lymphocyte (CTL) responses were detected in LSC63 before seroconversion. Compared to those detected after seroconversion, these responses were of lower magnitude and half of them targeted different regions of the viral proteome. Strong HLA-B27-restricted CTLs, which have been associated with disease control, were detected in LSC63 after but not before seroconversion. Furthermore, for the majority of the protein-coding regions of the HIV-1 variants in LSC63 (except gp41, nef, and the 3′ half of pol), the genetic distances between the infecting viruses and the viruses to which he was exposed through P63 (termed the exposed virus) were comparable to the distances between random subtype B HIV-1 sequences and the exposed viruses. These results suggest that broad preinfection immune responses were not able to prevent the acquisition of HIV-1 infection in LSC63, even though the infecting viruses were not particularly distant from the viruses that may have elicited these responses.Understanding the mechanisms of altered susceptibility or control of human immunodeficiency virus type 1 (HIV-1) infection in highly exposed seronegative (ES) persons may provide invaluable information aiding the design of HIV-1 vaccines and therapy (9, 14, 15, 33, 45, 57, 58). In a cohort of female commercial sex workers in Nairobi, Kenya, a small proportion of individuals remained seronegative for over 3 years despite the continued practice of unprotected sex (12, 28, 55, 56). Similarly, resistance to HIV-1 infection has been reported in homosexual men who frequently practiced unprotected sex with infected partners (1, 15, 17, 21, 61). Multiple factors have been associated with the resistance to HIV-1 infection in ES individuals (32), including host genetic factors (8, 16, 20, 37-39, 44, 46, 47, 49, 59, 63), such as certain HLA class I and II alleles (41), as well as cellular (1, 15, 26, 55, 56), humoral (25, 29), and innate immune responses (22, 35).Seroconversion in previously HIV-resistant Nairobi female commercial sex workers, despite preexisting HIV-specific cytotoxic T-lymphocyte (CTL) responses, has been reported (27). Similarly, 13 of 125 ES enrollees in our Seattle ES cohort (1, 15, 17) have become late seroconverters (H. Zhu, T. Andrus, Y. Liu, and T. Zhu, unpublished observations). Here, we analyze the virology, genetics, and immune responses of HIV-1 infection in one of the later seroconverting subjects, LSC63, who had developed broad CTL responses before seroconversion. 相似文献