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 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 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 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.     

Is early osteoarthritis associated with differences in joint congruence?

Previous studies suggest that osteoarthritis (OA) is related to abnormal or excessive articular contact stress. The peak pressure resulting from an applied load is determined by many factors, among which is shape and relative position and orientation of the articulating surfaces or, referring to a more common nomenclature, joint congruence. It has been hypothesized that anatomical differences may be among the causes of OA. Individuals with less congruent joints would likely develop higher peak pressure and thus would be more exposed to the risk of OA onset. The aim of this work was to determine if the congruence of the first carpometacarpal (CMC) joint differs with the early onset of OA or with sex, as the female population has a higher incidence of OA. 59 without and 38 with early OA were CT-scanned with their dominant or arthritic hand in a neutral configuration. The proposed measure of joint congruence is both shape and size dependent. The correlation of joint congruence with pathology and sex was analyzed both before and after normalization for joint size. We found a significant correlation between joint congruence and sex due to the sex-related differences in size. The observed correlation disappeared after normalization. Although joint congruence increased with size, it did not correlate significantly with the onset of early OA. Differences in joint congruence in this population may not be a primary cause of OA onset or predisposition, at least for the CMC joint.     

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 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 there a haemodynamic advantage associated with cuffed arterial anastomoses?

The development of intimal hyperplasia at arterial bypass graft anastomoses is a major factor responsible for graft failure. A revised surgical technique, involving the incorporation of a small section of vein (vein cuff) into the distal anastomosis of PTFE grafts, results in an altered distribution of intimal hyperplasia and improved graft patency rates, especially for below-knee grafts. Numerical simulations have been conducted under physiological conditions to identify the flow behaviour in a typical cuffed bypass model and to determine whether the improved performance of the cuffed system can be accounted for by haemodynamic factors. The flow patterns at the cuffed anastomosis are significantly different to those at the conventional end-to-side anastomosis. In the former case, the flow is characterised by an expansive, low momentum recirculation within the cuff. Separation occurs at the graft heel, and at the cuff toe as the blood enters the recipient artery. Wall shear stresses in the vicinity of the cuff heel are low, but high shear stresses and large spatial gradients in the shearing force act on the artery floor during systole. In contrast, a less disturbed flow prevails and the floor shear stress distribution is less adverse in the conventional model. In conclusion, aspects of the anastomotic haemodynamics are worsened when the cuff is employed. The benefits associated with the cuffed grafts may be related primarily to the presence of venous material at the anastomosis. Therefore, caution is advised with regard to the use of PTFE grafts, pre-shaped to resemble a cuffed geometry.     

Is enhanced free radical flux associated with increased intracellular proteolysis?

Intracellular proteolysis was measured in cultured cells during and after free radical attack. Radicals were generated firstly, throughout the aqueous phase by gamma irradiation and secondly, selectively, either extracellularly or intracellularly by chemical and enzymic methods. With both approaches, stimulation of proteolysis was observed in certain circumstances. Phenylhydrazine stimulated proteolysis at low concentration but inhibited at higher. Depletion of the antioxidant glutathione and inhibition of catalase also increased proteolysis.     

Is Saccharomyces cerevisiae apoptotic cell death associated with gene transfer?

Programmed cell death in unicellular organisms is difficult to account for in evolutionary terms. In the budding yeast, Saccharomyces cerevisiae, existence of several morphological and biochemical features of apoptosis has been described, and genes responsible for execution of the death program have been identified. It is here suggested that apoptosis of yeast cells could provide direct benefit to the genes of the dying cells, by facilitating DNA transfer to surrounding cells. The biochemical details of yeast apoptotic death are considered in light of a gene transfer hypothesis.     

Is sociality associated with high longevity in North American birds?

Sociality, as a life-history trait, should be associated with high longevity because complex sociality is characterized by reproductive suppression, delayed breeding, increased care and survival, and some of these traits select for high longevity. We studied the relationship between cooperative parental care (a proxy of complex sociality) and relative maximum lifespan in 257 North American bird species. After controlling for variation in maximum lifespan explained by body mass, sampling effort, latitude, mortality rate, migration distance and age at first reproduction, we found no significant effect of cooperative care on longevity in analyses of species-specific data or phylogenetically independent standardized linear contrasts. Thus, sociality itself is not associated with high longevity. Rather, longevity is correlated with increased body size, survival rate and age of first reproduction.     

Is Canada's sex ratio in decline?

In this issue (see pages 37 to 41) Dr. Bruce B. Allan and associates report a small but statistically significant decrease--of about 0.2%--in the proportion of male live births in Canada over the period 1970-90. In this editorial, factors that have been reported in the literature to influence sex ratio are examined within a Canadian context. The authors suggest that although the reasons for the apparent decline in the sex ratio in Canada are unclear, the increasing use of ovulation induction may be a contributing factor. Data from the Nova Scotia Atlee Perinatal Database are discussed with a view to explaining the trend observed in Atlantic Canada, but no obvious explanation emerges. The authors argue that when the period of observation is extended no overall change in the sex ratio is apparent. This would suggest a tendency toward stabilization rather than decline.     

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.     

Is a joint moment-based cost function associated with preferred cycling cadence?

Eight experienced male cyclists (C), eight well-trained male runners (R), and eight less-trained male noncyclists (LT) were tested under multiple cadence and power output conditions to determine: (1) if the cadence at which lower extremity net joint moments are minimized (cost function cadence) was associated with preferred pedaling cadence (PC), (2) if the cost function cadence increased with increases in power output, and (3) if the association is generalizable across groups differing in cycling experience and aerobic power. Net joint moments at the hip, knee, and ankle were computed from video records and pedal reaction force data using 2-D inverse dynamics. The sum of the average absolute hip, knee, and ankle joint moments defined a cost function at each power output and cadence and provided the basis for prediction of the cadence which minimized net joint moments for each subject at each power output. The cost function cadence was not statistically different from the PC at each power output in all groups. As power output increased, however, the cost function cadence increased for all three subject groups (86 rpm at 100 W, 93 rpm at 150 W, 98 rpm at 200 W, and 96 rpm at 250 W). PC showed little change (R) or a modest decline (C, LT) with increasing power output. Based upon the similarity in the mean data but different trends in the cost function cadence and PC in response to changes in power output as well as the lack of significant correlations between these two variables, it was concluded that minimiking net joint moments is a factor modestly associated with preferred cadence selection.