Is Acanthamoeba pathogenicity associated with intracellular bacteria?

In addition to the possible role of Acanthamoeba as an evolutionary precursor of pathogenicity in microbial pathogens, it has been suggested that intracellular bacteria or other microbial endosymbionts may also enhance the pathogenicity of Acanthamoeba. Using transmission electron microscopy, polymerase chain reaction and simple culturing, our findings did not reveal any apparent evidence of microbial presence intracellularly of a recently recovered clinical isolate of Acanthamoeba. Based on these findings, it is tempting to speculate that the virulence of Acanthamoeba may not be attributed to the pathogenicity of the endosymbiont alone.     

Is regulation of proteolysis associated with redox-state changes in rat skeletal muscle?

In isolated rat diaphragms, only those substrates that increased the tissue NADH/NAD+ ratio lowered the rate of proteolysis. However, direct inhibition of proteinase activity by leupeptin promoted oxidation of the NAD couple of the muscles. These results suggest that changes in muscle reduction-oxidation state may be important in the regulation of proteolysis.     

Is mating of copepods associated with increased risk of predation?

In laboratory experiments, we tested whether the cyclopoid copepodCyclops vicinus is more vulnerable to predation by juvenile(young-of-the-year) roach (Rutilus rutilus) and/or larvae ofthe phantom midge Chaoborus flavicans during mating than individualadult copepods of the same species. We also tested whether C.vicinusavoided mating, displayed shorter mating times and/or loweractivity when a predator (Chaoborus) was present, or when exposedto water in which predators (Chaoborus) were previously held.Fish ate the same quantity of pairs in copulation and individualegg-bearing females but significantly fewer females withouteggs. Chaoborus ate similar quantities of pairs and femalesbut fewer males. Pairs in copulation and egg-bearing femaleswere detected earlier by fish than individual non-ovigerousfemales or males, and pairs in copulation were captured mosteasily by fish. Cyclops vicinus mated less often when Chaoboruslarvae were present than in water in which Chaoborus was previouslyheld, or in pure tap water. However, predator presence or exposureto predator-treated water had no effect on (i.e. did not reduce)mating duration. Activity of C.vicinus pairs during copulationwas significantly lower when a predator was present, or in predator-treatedwater, than in pure tap water, and activity of pairs decreasedwith increasing activity of the predator. Although our experimentswere carried out under artificial conditions which cannot betransferred to the complex conditions in the field, they suggestthat mating in copepods is dangerous and that copepods haveevolved particular strategies to reduce the risk of predationduring mating.     

Is transformation associated with an increased error frequency in mammalian cells?

Acute starvation of mammalian cells for amino acids results in translational errors that may be detected by two-dimensional polyacrylamide gel electrophoresis. Using this as an assay for error frequency in mammalian cells, we investigated the hypothesis that neoplastic transformation was associated with an increased error frequency which in turn leads to an increased mutation rate and a decreased efficiency of regulatory controls (phenomena of tumor progression). Although we found that transformation was not always associated with an increased level of mistranslation we showed that SV40 transformation increased the level of translational errors in all cell types tested.     

Is recurrent low back trouble associated with increased lumbar sagittal mobility?

The hypothesis that increased lumbar sagittal mobility constitutes a risk factor for recurrent low back trouble was tested in respect of two specific groups of subjects thought likely to display this phenomenon: young females reporting recurrent back pain, and middle-aged adults reporting recurrent or persistent sciatic symptoms. Lumbar flexibility was estimated from back surface curvatures by a validated technique which uses a flexicurve to record mobility in upper (T12-L4) and lower (L4-S2) lumbar regions. Mean mobility for young females (<40 years) with recurrent back pain was less, though not significantly so, than those without back trouble. A loss of mobility was also found in young males with recurrent trouble. However, it was a proportionally greater loss than that found in the females and was statistically significant. The mean mobility for middle-age adults with recurrent sciatic symptoms was significantly reduced compared to those without a history of back trouble. Whilst these results failed to support the general hypothesis, it remains possible that aspects of increased mobility not studied here, such as localized segmental instability or abnormal coupled motions, may be associated with an increased frequency of recurrent low back trouble.     

Oxidative stress and potential free radical damage associated with photocopying. A role for ozone?

OBJECTIVE: To study the relationship between oxidative stress and potential free radical damage associated with photocopying and to explore a role for ozone emitted during the photocopying process. METHODS: 80 photocopying operators (PO) and 80 healthy volunteers (HV) were enrolled in a random control study design, in which the level of lipoperoxide (LPO, thiobarbituric acid reactive substances, TBARS) in erythrocytes and the levels of vitamin C (VC), vitamin E (VE) and beta-carotene (beta-CAR) in plasma as well as the activities of superoxide dismutase (SOD) and catalase (CAT) in erythrocytes were determined by spectrophotometric methods. RESULTS: Compared with the average values of the above biochemical parameters in the HV group, the average value of LPO (TBARS) in erythrocytes in the PO group was significantly increased (P < 0.0001), while the average values of VC, VE and beta-CAR in plasma as well as those of SOD and CAT in erythrocytes in the PO group were significantly decreased (P < 0.0001). Pearson product-moment correlation analysis showed that with the increase of the ozone level in photocopying sites and the PO duration of exposure to ozone, the level of LPO in erythrocytes in the operators was increased (P < 0.001), while the levels of VC, VE and beta-CAR in plasma as well as the activities of SOD and CAT in erythrocytes in the operators were decreased (P < 0.01-0.0001). CONCLUSION: The findings in this study suggest that ozone causes oxidative damage in copier operatives.     

Is low-frequency distribution of TGF-beta genotype associated with increased risk for end-stage renal disease?

End-stage renal disease has been associated with an inflammatory state. TGF-beta plays a critical role in antiinflammation counteracting inflammatory cytokines, wound healing, and tissue repair. We, therefore, speculated the protective role of TGF-beta in renal inflammation rather than inducing fibrosis. Three polymorphisms of TGF-beta (713-8delC), i.e., C deletion in intron sequence 8 base prior to exon-5 by PCR-RFLP and codon-10, Leu/Pro, and codon-25, Arg/Pro by Amplification Refractory Mutation System (ARMS-PCR) techniques were genotyped in 228 end-stage renal disease (ESRD) patients and 180 controls. Linkage disequilibrium (LD) and haplotype analysis was performed by Arlequin software. Our data showed positive association between codon-10 polymorphism and ESRD risk (P < 0.001; OR 4.845, 95% CI 2.57-9.11 for Pro/Pro). However, genotype frequencies were comparable in patients and controls for 713-8delC, while in the case of codon-25, a trend of higher frequency of Pro/Pro genotype (16.2% versus 10.0%) was observed but the P-value did not reach significant (P = 0.187). Significant association of codon-10 Pro/Pro was observed in patients with glomerulonephritis (P = 0.001; OR 4.138, 95%CI 2.1-8.13). LD was found significant between codon-10 and 25 (P = 0.021). Haplotype "Pro-Pro" showed 1.8-fold higher risk for ESRD (p = 0.003; OR = 1.867, 95%CI = 1.229-2.838). A combined analysis of the effect of TGF-beta (codon-10) with C-deletion and codon-25 showed significant difference for TGF-beta(10)-TGF-beta(C-del) (P = 0.010). In conclusion, the present study suggests that low-producing genotype (Pro/Pro) of TGF-beta (codon-10) polymorphism is associated with ESRD. Haplotype analysis further suggested that "Pro-Pro" (low producer) is associated with higher risk for ESRD. Thus, high-producing genotype of TGF-beta may be beneficial and may play a potential role in the resolution of renal inflammation.     

Is running performance enhanced with creatine serum ingestion?

Runners Advantage (RA) creatine (Cr) serum has been marketed to increase running performance. To test this claim, cross-country runners completed baseline testing (BASE), an outdoor 5,000-m run followed by treadmill Vo(2)max testing on the same day. Subjects repeated testing after ingesting 5 ml of RA (n = 13) containing 2.5 g of Cr or placebo (n = 11). Heart rate (HR), rating of perceived exertion (RPE), and run time were recorded. With RA (56.48 +/- 8.93 ml.kg(-1.)min(-1)), Vo(2)max was higher (p = 0.01) vs. BASE (54.07 +/- 9.36 ml.kg(-1.)min(-1)), yet the magnitude of the increase was within the coefficient of variation of Vo(2)max. No effect of RA on maximal HR was exhibited, yet Vco(2)max and duration of incremental exercise were significantly higher (p < 0.025) vs. BASE. Vo(2)max was similar in PL (58.85 +/- 6.67 ml.kg(-1).min(-1)) and BASE (57.28 +/- 7.22 ml.kg(-1.)min(-1)). With RA, the 5,000-m time was unchanged, and RPE was lower (p < 0.025) vs. BASE. These data do not support the ergogenic claims of RA in its current form and dose.     

Is HIV infection associated with an increased risk for cholera? Insights from a mathematical model

Cholera, a waterborne gastroenteric infection, remains a significant threat to public health in sub-Saharan Africa, the region most heavily affected by HIV. It is biologically plausible that immune suppression caused by HIV infection predisposes to cholera. In this paper, a simple mathematical model is developed and comprehensively analyzed to assess whether HIV infection is associated with an increased risk for cholera or not. Analytical results of the model show that the quantities R(c) and R(h), which represents the reproductive number for cholera and HIV infection, respectively, provide threshold conditions that determine cumulative new single and dual infection cases. These threshold conditions can be used to gain important insights on the epidemiological consequences of HIV and cholera coexistence in the community. Numerical results are provided to support the analytical findings. The findings suggest that in a cholera-endemic area, HIV infection is associated with an increased risk for cholera.     

Is interleukin-18 associated with polycystic ovary syndrome?

Background  

Recent research show that polycystic ovary syndrome (PCOS) may have an association with low-grade chronic inflammation, IL-18 is considered as a strong risk marker of inflammation.     

Is the ApoE polymorphism associated with dilated cardiomyopathy?

Apolipoprotein E (ApoE) is 34 kDa protein involved in the modulation of cholesterol transport and homeostasis. Polymorphism of the ApoE gene has been implicated in many chronic cardiovascular and neuronal diseases. ApoE epsilon4 allele has been reported to be associated with increased risk of cardiovascular diseases such as myocardial infarction, hypertension, coronary heart disease, etc. Fifty patients with the end-stage dilated cardiomyopathy (DCM) and advanced congestive heart failure were examined in our study. For evaluation of ApoE polymorphism, novel approach of fast screening of ApoE gene polymorphism by combination of PCR and blotting (CVD StripAssay) was used. Individual genotypes were correlated with basic cardiologic clinical parameters. The reported frequency of this allele in Caucasian population is 14.7 %. Our results showed that in patients with DCM frequency of the ApoE epsilon4 allele is 40 %. Frequency of the genotype epsilon2/4 was 58 % and epsilon3/4 was 22 %. Comparison with control Caucasian groups monitored by others clearly revealed that frequency of epsilon4 alelle is increased in patients with advanced stages of DCM. This observation suggests association of ApoE polymorphism with severe form of DCM. Physiological consequences of this observation remain to be clarified.     

Is there evidence for excessive free radical production in vivo during ultrasound-assisted liposuction?

The surgical technique of ultrasound-assisted liposuction has become a standard procedure for the treatment of lipodystrophy. However, little is known about the impact of this therapy on fatty tissue on the molecular level. There are concerns about possible adverse effects related to the high-intensity ultrasound energy, because in vitro studies have shown a substantial generation of free radicals. In this study, the authors investigated whether ultrasound waves can create an excessive free radical production in vivo by measuring lipid peroxidation products in the form of malondialdehyde equivalents. For this purpose, the thiobarbituric acid-reactive substances (TBARS) assay was chosen. In this test, malondialdehyde, a major product of lipid peroxidation, reacts with thiobarbituric acid to produce a pink adduct that can be measured spectrophotometrically. The authors determined oxidation products in 28 aspirates of 17 treated patients before ultrasound-assisted liposuction (0 minutes) to establish a baseline concentration and at 2, 5, and 10 minutes after the treatment was begun. Median malondialdehyde concentration of the control group (conventional liposuction, 0 minutes) was 3.40 nmol of malondialdehyde per gram of adipose tissue. Median concentrations after 2, 5, and 10 minutes of ultrasound-assisted liposuction were 7.45 (n = 28), 8.84 (n = 21), and 4.07 (n = 8) nmol malondialdehyde per gram adipose tissue, respectively. The differences were not statistically significant. The data suggest that there is no excessive formation of lipid oxidation products in response to free radicals. The antioxidative capacity of adipose tissue does not seem to be overwhelmed by the standard application regimen of ultrasound-assisted liposuction.     

Is promiscuity associated with enhanced selection on MHC-DQα in mice (genus Peromyscus)?

Reproductive behavior may play an important role in shaping selection on Major Histocompatibility Complex (MHC) genes. For example, the number of sexual partners that an individual has may affect exposure to sexually transmitted pathogens, with more partners leading to greater exposure and, hence, potentially greater selection for variation at MHC loci. To explore this hypothesis, we examined the strength of selection on exon 2 of the MHC-DQα locus in two species of Peromyscus. While the California mouse (P. californicus) is characterized by lifetime social and genetic monogamy, the deer mouse (P. maniculatus) is socially and genetically promiscuous; consistent with these differences in mating behavior, the diversity of bacteria present within the reproductive tracts of females is significantly greater for P. maniculatus. To test the prediction that more reproductive partners and exposure to a greater range of sexually transmitted pathogens are associated with enhanced diversifying selection on genes responsible for immune function, we compared patterns and levels of diversity at the Class II MHC-DQα locus in sympatric populations of P. maniculatus and P. californicus. Using likelihood based analyses, we show that selection is enhanced in the promiscuous P. maniculatus. This study is the first to compare the strength of selection in wild sympatric rodents with known differences in pathogen milieu.     

Is circadian type associated with sleep duration in twins?

Sleep and Biological Rhythms - We used the community-based University of Washington Twin Registry to investigate the genetic association between circadian type and sleep duration. Habitual sleep...     

Is herpes simplex virus associated with peptic ulcer disease?

To test the hypothesis that herpes simplex virus type 1 (HSV-1) may be associated with peptic ulcer disease, we examined ulcerative lesions of the distal stomach and proximal duodenum for the presence of nucleic acids and antibodies specific for HSV-1. Utilizing in situ hybridization, immunocytochemistry, and polymerase chain reaction with sequencing, gastric or duodenal tissues from 4 of 22 patients (18%) with documented peptic ulcer disease demonstrated the presence of both specific HSV-1 nucleic acid sequences and proteins. HSV-1 was found restricted in clusters of cells near the margin of the ulcer but was absent at sites distal to the lesion. Several of such HSV-1-infected cells also contained cholecystokinin. These cholecystokinin-containing cells are of neuroendocrine origin and receive contact from the vagal nerve. Campylobacter pylori bacteria were not found in three of the four peptic ulcer tissues that harbored HSV-1. Further, none of the stomach or duodenal tissue samples from 33 patients undergoing clinical evaluation, but having no evidence of peptic ulcer disease, had HSV-1 materials. Thus, our data suggest that a subset of peptic ulcer disease may be associated with HSV-1 and raise the possibility that some peptic ulcers may be caused by this virus.