Australia Antigen in a Closed Adult Population Monitored for Serum Glutamic Oxalacetic Transaminase

A study of the presence of Australia antigen (Au/SH) was conducted over a period of 21 weeks among volunteer plasma donors living in a prison and being monitored for serum glutamic oxalacetic transaminase (SGOT). A good correlation was observed between the level of SGOT and presence of Au/SH, the latter being present in 33% of donors with SGOT values higher than 101 Karmen units and in 12% of those with SGOT values of 41 to 100 units. Furthermore, none of the 87 donors with all SGOT values below 40 was found positive for Au/SH. It should be noted, however, that single specimens only were tested from 72 of the 87 individuals. Au/SH was detected with equivalent efficiency by both agar gel precipitation and complement fixation procedures. Implications of these findings in the prognostication of hepatitis carrier state are discussed.     

Loss of Population Levels of Immunity to Malaria as a Result of Exposure-Reducing Interventions: Consequences for Interpretation of Disease Trends

Background

The persistence of malaria as an endemic infection and one of the major causes of childhood death in most parts of Africa has lead to a radical new call for a global effort towards eradication. With the deployment of a highly effective vaccine still some years away, there has been an increased focus on interventions which reduce exposure to infection in the individual and –by reducing onward transmission-at the population level. The development of appropriate monitoring of these interventions requires an understanding of the timescales of their effect.

Methods & Findings

Using a mathematical model for malaria transmission which incorporates the acquisition and loss of both clinical and parasite immunity, we explore the impact of the trade-off between reduction in exposure and decreased development of immunity on the dynamics of disease following a transmission-reducing intervention such as insecticide-treated nets. Our model predicts that initially rapid reductions in clinical disease incidence will be observed as transmission is reduced in a highly immune population. However, these benefits in the first 5–10 years after the intervention may be offset by a greater burden of disease decades later as immunity at the population level is gradually lost. The negative impact of having fewer immune individuals in the population can be counterbalanced either by the implementation of highly-effective transmission-reducing interventions (such as the combined use of insecticide-treated nets and insecticide residual sprays) for an indefinite period or the concurrent use of a pre-erythrocytic stage vaccine or prophylactic therapy in children to protect those at risk from disease as immunity is lost in the population.

Conclusions

Effective interventions will result in rapid decreases in clinical disease across all transmission settings while population-level immunity is maintained but may subsequently result in increases in clinical disease many years later as population-level immunity is lost. A dynamic, evolving intervention programme will therefore be necessary to secure substantial, stable reductions in malaria transmission.     

Development of heartwood in response to water stress for radiata pine in Southern New South Wales, Australia

Heartwood development and other functional changes in stem conductance in response to water stress in radiata pine were investigated using two contrasting climatic areas (high-altitude sub-alpine vs. warm–dry inland) of the Hume region of New South Wales, Australia. The study included mature (34.5–36.5 years old) and young stands (10–11 years old) measured under normal climate and during an extreme drought. The effect of water stress on heartwood development was examined using sapwood percentage, sapwood saturation, development of dry sapwood and evidence of cavitation in sapwood. Trees at the warm–dry site developed heartwood at faster rates than on the high-altitude site. At breast height, the mature stands of the warm–dry site had 8–14 % less sapwood. Extensive cavitation towards the sapwood/heartwood boundary occurred in some of the mature and young stands on the warm–dry site. We postulated that in water-limiting environments, cavitation of the inner sapwood precedes heartwood formation and is an adaptation mechanism that regulates stem conductance capacity and thus water use in the tree. The drought of 2006 led to decreases in moisture associated with cavitation not previously reported for radiata pine and demonstrated the drought hardiness of the species. In the warm–dry site, breast-height sapwood saturation dropped to 58 and 82 % for suppressed and average-sized trees in a mature unthinned stand; and 75–78 % for two young stands. These saturation levels, however, only imply average values as some cells cavitated whilst others were fully saturated. Cavitation occurred in a localized fashion affecting small to large groups of cells.     

High Prevalence and Associated Risk Factors for Impaired Renal Function and Urinary Abnormalities in a Rural Adult Population from Southern China

Background

The prevalence of chronic kidney disease (CKD) has increased and will continue to rise worldwide. However, data regarding the prevalence of CKD in a rural area of China are limited. We therefore investigated the prevalence and associated risk factors of impaired renal function and urinary abnormalities in an adult rural population in southern China.

Methods

Between December 2006 and January 2007, residents older than 20 years from four villages in Zhuhai city were randomly selected using a stratified, multistage sampling technique. All participants were interviewed and tested for hematuria, albuminuria and estimated glomerular filtration rate (eGFR). The associations between age, gender, diabetes mellitus, hypertension, hyperuricemia, education level and indicators of renal damage were examined.

Results

Overall, 1,214 subjects were enrolled in this study. After adjustment for age and gender, the prevalence of albuminuria was 7.1% (95% CI: 4.5, 8.1), reduced eGFR was 2.6% (95% CI: 1.7%, 3.3%), and hematuria was 4.6% (95% CI: 3.3%, 6.0%). Approximately 13.6% (95% CI: 12.0%, 15.1%) of the patients had at least one indicator of renal damage, but only 8.3% were previously aware. Age, diabetes, hyperlipidemia, hypertension, hyperuricemia, use of nephrotoxic medications, coronary heart disease and history of CKD were independently associated with impaired renal function and urinary abnormalities. Additionally, age, diabetes, and hypertension were independently associated with albuminuria. Age, hypertension, hyperuricemia, central obesity, and coronary heart disease were independently associated with reduced renal function.

Conclusions

The high prevalence and low awareness of impaired renal function and urinary abnormalities in this population illustrates the urgent need to implement a CKD prevention program in the rural areas of southern China.     

Mapping of a Heat-Stable Gene for Resistance to Southern Root-Knot Nematode in Solanum lycopersicum

Root-knot nematodes (Meloidogyne spp.) can cause severe problems in tomato production in warm climates. To date, Mi-1 is the only gene that has been used widely to develop cultivars for controlling disease caused by nematodes around the world. However, Mi-1 does not provide resistance to the pest when the soil temperature is above 28 °C. Tomato breeding line ZN17 has been reported to possess resistance to Meloidogyne incognita at high temperatures (32 °C). To identify markers linked tightly to resistance, an F₂ population was developed by crossing the resistance line ZN17 to susceptible line 09C84. Analysis of F₂ individuals by inoculating M. incognita suggested that resistance in ZN17 is conditioned by a single dominant gene temporarily designated as Mi-HT. Linkage analysis suggested that Mi-HT is located on the short arm of chromosome 6. One marker, W737, co-segregated with Mi-HT. Comparisons of map positions of Mi-HT, Mi-1, and Mi-9, as well as marker genotypes in LA2157, Motelle, and ZN17 suggested that Mi-HT might be a homologue of Mi-1 and Mi-9 or a new gene. The results obtained in this study will facilitate fine-mapping and cloning of the gene as well as marker-assisted breeding for heat-stable resistance to southern root-knot nematodes in tomato.     

Decline in serum antibodies to methyltetrahydrophthalic anhydride after cessation of exposure.Implications for use as a biomarker

T he association between exposure intensity and serum levels of immunoglobulins E and G against low molecular weight compounds was evaluated. The decay of levels of specific IgE and IgG antibodies was studied after cessation of exposure in workers exposed to the inhalant allergen methyltetrahydrophthalic anhydride in a plant using epoxy resins. Sera have been collected in workers for 18-84 (mean value 54) months after cessation of exposure. Specific IgE and IgG was assessed by RAST and ELISA, respectively. The mean of individual half-times for IgE ( N = 10) and IgG ( N = 8) was 0 9 (range 0 1-1 8) and 0 4 (range 0 2-0 6) years, respectively, after total avoidance of exposure. Corresponding decreases of IgE and IgG were also observed after reduction, but not total elimination, of exposure. No correlation was seen between biologic halftimes of specific IgE and total IgE, atopy, smoking habits or gender. The results indicate that the levels of specific antibodies in sensitized individuals reflect long term exposure, and may persist for years after the end of exposure.     

Response to Selection and Inbreeding Depression in a Dynamic Population for Amount of Inbreeding

A method for predicting response to selection and inbreeding depression in a dynamic population for amount of inbreeding was derived and illustrated with an example of selection under full-sib mating.     

Willingness to Pay for Cataract Surgery Provided by a Senior Surgeon in Urban Southern China

Purpose

To study willingness to pay for cataract surgery and surgical service provided by a senior cataract surgeon in urban Southern China.

Methods

This study was a cross-sectional willingness-to-pay (WTP) interview using bidding formats. Two-hundred eleven persons with presenting visual impairment in either eye due to cataract were enrolled at a tertiary eye hospital. Participants underwent a comprehensive eye examination and a WTP interview for both surgery and service provided by a senior surgeon. Demographic information, socioeconomic status and clinical data were recorded.

Results

Among 211 (98% response rate) persons completing the interview, 53.6% were women and 80.6% were retired. About 72.2% had a monthly income lower than 1000 renminbi (US $161). A total of 189 (89.6%) were willing to pay for cataract and the median amount of WTP was 6000 renminbi (US$968). And 102 (50.7%) were willing to pay additional fees for surgery performed by a senior surgeon, and the median amount of WTP was 500 renminbi (US$81). In regression models adjusting for age and gender, persons with preexisting eye diseases other than cataract, were more likely to pay for cataract surgery and service provided by a senior surgeon (P = 0.04 for both).

Conclusions

In urban China, cataract patients, especially those with preexisting eye conditions, are willing to pay additional fees for a senior surgeon. Moving to a system where the price of cataract surgery is proportional to the consultant’ skill and expertise is possible and may have a potential impact on waiting list and quality of eye care. Further studies are needed to examine the impact of such pricing system on attitudes and choices of cataract patients.     

Food deprivation is not a prerequisite for the amoebal to plasmodial transition in Physarum polycephalum

The effect of food supply on the onset of asexual and sexual plasmodium formation in Physarum polycephalum was studied. Asexual differentiation occurs readily in amoebae carrying the matAh mating type allele. The density at which these amoebae begin to differentiate is influenced by the ind locus, which controls the production of a diffusible inducer. The alleles ind-1 and ind-2 are known. Strains carring the ind-1 allele begin plasmodium formation at a low amoebal density (rapid differentiation), while strains carring the ind-2 allele differentiate at a higher amoebal density (slow differentiation). The onset of differentiation is characteristic of the strain and did not change with a 20-fold variation in the number of food bacteria available. Sexual differentiation occurs between compatible amoebal strains. For a given pair of amoebal strains the onset of plasmodium formation occurs at a characteristic cell density that is determined by the genetic backgrounds of the strains. The ind locus is one of the genes that influences this cell density. Plasmodia are formed at a lower cell density in crosses involving compatible amoebae carrying the ind-1 allele than they are in crosses with strains carrying the ind-2 allele. As was found for asexual differentiation, an approximate 20-fold variation in the food supply did not affect the initiation of sexual plasmodium formation. These results suggest that in most cases starvation does not trigger the differentiation of amoebae into plasmodia. The time of onset of plasmodium formation is determined largely by genetic factors.     

No Evidence for Adaptive Micro-Evolution to a Decrease in Phosphorus-Loading of a Daphnia Population Inhabiting A Pre-Alpine Lake

Many polluted lakes in Europe are being restored and phosphorus concentrations have dropped dramatically in these lakes. We studied the genetic structure of Daphnia galeata over the past 30 years in Lake Greifensee, Switzerland, a period during which the phosphorus concentration in the lake reduced dramatically. Distinct genotypes of D. galeata were hatched from diapausing eggs extracted from six different time horizons in dated sediments. We compared juvenile growth, size and egg production of D. galeata reared on high-P and low-P algae to investigate whether Daphnia have evolved to grow better on phosphorus-limited algae. Our results indicate that life histories of D. galeata differed significantly between both food types. We also found significant clone effects for size and egg number. But we found no significant interaction between the depth from which the clones were selected and food quality. This means that we found no evidence for adaptive micro-evolution in response to P reduction in the lake. We discuss our results in relation to other studies that found evidence for adaptive micro-evolution in comparable time frames.     

High Genetic Variability for Resistance to Bacillus thuringiensis Toxins in a Single Population of Diamondback Moth

The long-term benefit of insecticidal products based on Cry toxins, either in sprays or as transgenic crops, is threatened by the development of resistance by target pests. The models used to predict evolution of resistance to Cry toxins most often are monogenic models in which two alleles are used. Moreover, the high-dose/refuge strategy recommended for implementation with transgenic crops relies on the assumption that the resistance allele is recessive. Using selection experiments, we demonstrated the occurrence in a laboratory colony of diamondback moth of two different genes (either allelic or nonallelic) that confer resistance to Cry1Ab. At the concentration tested, resistance was dominant in one selection line and partially recessive in the other. Resistant insects from the two selection lines also differed in their cross-resistance patterns. The diamondback moth colony was derived from a field population from the Philippines, which originally showed a different resistance phenotype. This is the first time that an insect population has been directly shown to carry more than one gene conferring resistance to the same Cry toxin.     

Population sex ratio shift from fledging to recruitment: consequences for demography in a philopatric seabird

In many dimorphic bird species, offspring sex ratio is skewed towards the production of the smaller sex. Offspring sex ratio can be biased in monomorphic birds however, and the demographic consequences of such bias are unknown. Sex-specific mortality and dispersal are fundamental mechanisms of sex ratio adjustment at the population level, but evidence for adjustments is weak and feedback into population dynamics poorly understood. Here, we link sex ratio at fledging with sex-specific subadult return and recruitment at the Banter See common tern Sterna hirundo colony. Using molecular sexing methods and a remote detection system, we permanently tracked individuals from four complete cohorts (n=1171 fledglings) across these life-history stages at their natal colony site, which permitted a structured analysis of sex ratio across multiple seasons. Sex ratio shifted significantly from significant daughter dominance at fledging to higher proportions of natal males among recruits; return and recruitment rates of sons were significantly higher than daughters (p≤0.002). No significant between-year differences were detected. 47.4% of natal male recruits were paired with a non-natal female, but only 37.0% of natal female recruits had a non-natal partner. Elasticity analysis suggested that natal males have a greater influence on natal population growth rate than natal females. Sex biased dispersal is the most probable reason for these results indicating higher emigration to and immigration from other colonies in females, the less territorial and less philopatric sex. This pattern may be related to different gender roles in parental duties and with respect to competition for local resources.     

Characterizing the Aedes aegypti Population in a Vietnamese Village in Preparation for a Wolbachia-Based Mosquito Control Strategy to Eliminate Dengue

Background

A life-shortening strain of the obligate intracellular bacteria Wolbachia, called wMelPop, is seen as a promising new tool for the control of Aedes aegypti. However, developing a vector control strategy based on the release of mosquitoes transinfected with wMelPop requires detailed knowledge of the demographics of the target population.

Methodology/Principal Findings

In Tri Nguyen village (611 households) on Hon Mieu Island in central Vietnam, we conducted nine quantitative entomologic surveys over 14 months to determine if Ae. aegypti populations were spatially and temporally homogenous, and to estimate population size. There was no obvious relationship between mosquito (larval, pupal or adult) abundance and temperature and rainfall, and no area of the village supported consistently high numbers of mosquitoes. In almost all surveys, key premises produced high numbers of Ae. aegypti. However, these premises were not consistent between surveys. For an intervention based on a single release of wMelPop-infected Ae. aegypti, release ratios of infected to uninfected adult mosquitoes of all age classes are estimated to be 1.8–6.7∶1 for gravid females (and similarly aged males) or teneral adults, respectively. We calculated that adult female mosquito abundance in Tri Nguyen village could range from 1.1 to 43.3 individuals of all age classes per house. Thus, an intervention could require the release of 2–78 wMelPop-infected gravid females and similarly aged males per house, or 7–290 infected teneral female and male mosquitoes per house.

Conclusions/Significance

Given the variability we encountered, this study highlights the importance of multiple entomologic surveys when evaluating the spatial structure of a vector population or estimating population size. If a single release of wMelPop-infected Ae. aegypti were to occur when wild Ae. aegypti abundance was at its maximum, a preintervention control program would be necessary to ensure that there was no net increase in mosquito numbers. However, because of the short-term temporal heterogeneity, the inconsistent spatial structure and the impact of transient key premises that we observed, the feasibility of multiple releases of smaller numbers of mosquitoes also needs to be considered. In either case, fewer wMelPop-infected mosquitoes would then need to be released, which will likely be more acceptable to householders.     

Gut Endotoxin Leading to a Decline IN Gonadal function (GELDING) - a novel theory for the development of late onset hypogonadism in obese men

Obesity is an increasing public health problem, with two-thirds of the adult population in many Western countries now being either overweight or obese. Male obesity is associated with late onset hypogonadism, a condition characterised by decreased serum testosterone, sperm quality plus diminished fertility and quality of life. In this paper we propose a novel theory underlying the development of obesity related hypogonadism- the GELDING theory (Gut Endotoxin Leading to a Decline IN Gonadal function).Several observational studies have previously reported an association between obesity related hypogonadism (low testosterone) and systemic inflammation. However, for the first time we postulate that the trans-mucosal passage of bacterial lipopolysaccharide (LPS) from the gut lumen into the circulation is a key inflammatory trigger underlying male hypogonadism. Obesity and a high fat/high calorie diet are both reported to result in changes to gut bacteria and intestinal wall permeability, leading to the passage of bacterial endotoxin (lipopolysaccharide- LPS) from within the gut lumen into the circulation (metabolic endotoxaemia), where it initiates systemic inflammation. Endotoxin is known to reduce testosterone production by the testis, both by direct inhibition of Leydig cell steroidogenic pathways and indirectly by reducing pituitary LH drive, thereby also leading to a decline in sperm production.In this paper we also highlight the novel evolutionary benefits of the GELDING theory. Testosterone is known to be a powerful immune-suppressive, decreasing a man’s ability to fight infection. Therefore we postulate that the male reproductive axis has evolved the capacity to lower testosterone production during times of infection and resulting endotoxin exposure, decreasing the immunosuppressive influence of testosterone, in turn enhancing the ability to fight infection. While this response is adaptive in times of sepsis, it becomes maladaptive in the setting of “non-infectious” obesity related metabolic endotoxaemia.     

Unexpected Population Distribution in a Microbial Mat Community: Sulfate-Reducing Bacteria Localized to the Highly Oxic Chemocline in Contrast to a Eukaryotic Preference for Anoxia

The distribution and abundance of sulfate-reducing bacteria (SRB) and eukaryotes within the upper 4 mm of a hypersaline cyanobacterial mat community were characterized at high resolution with group-specific hybridization probes to quantify 16S rRNA extracted from 100-μm depth intervals. This revealed a preferential localization of SRB within the region defined by the oxygen chemocline. Among the different groups of SRB quantified, including members of the provisional families “Desulfovibrionaceae” and “Desulfobacteriaceae,” Desulfonema-like populations dominated and accounted for up to 30% of total rRNA extracted from certain depth intervals of the chemocline. These data suggest that recognized genera of SRB are not necessarily restricted by high levels of oxygen in this mat community and the possibility of significant sulfur cycling within the chemocline. In marked contrast, eukaryotic populations in this community demonstrated a preference for regions of anoxia.     

Population based ascertainment of twins and their siblings, born in Western Australia 1980 to 1992, through the construction and validation of a maternally linked database of siblings.

This paper describes the creation of a unique maternal identifier for use in the investigation of perinatal, postneonatal and child outcomes in relation to maternal characteristics. All Midwives' records of Western Australian (WA) births were routinely linked to registrations of births and deaths for infants born from 1980 to 1992 inclusive, then linked to WA hospital discharge data and to registries of birth defects and cerebral palsy to create a longitudinal health record for each infant. However, since each birth to a woman was recorded as a separate event, there was no way to identify siblings. Probabilistic record linkage, based on information about the mother, was used for this task. Logical inconsistencies within the data were used to test the validity of the linkages between birth records attributed to each mother. Information about the mother from other epidemiological studies and data abstracted from hospital case notes was also used to validate sibships. Linkage of the records of 310,255 births in WA during that period resulted in the formation of 181,133 sibships of one or more children. Pooling the results of all of the validation methods gave an error of 0.9%. Linkage identified 3678 sibships containing multiple births, and 305 sets of maternal twins. Ascertainment of twins and their siblings for an ongoing twin register, the WA Twin Child Health (WATCH) study, was a natural consequence of this process.