A case of cephalothoracopagus in sheep in Trinidad and Tobago.
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A case of cephalothoracopagus in sheep complicated with several defects of skeletal, cardiovascular, respiratory, gastrointestinal, and urogenital systems is reported. (+info)
Risk factors for urinary tract calculi in Trinidad.
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OBJECTIVE: To identify risk factors for urinary tract stones in Trinidad and Tobago. METHODS: A consecutive series of patients presenting to institutions in Trinidad for the management of proven urinary tract calculi was interviewed by questionnaires designed to obtain data on age, gender, ethnicity, occupation, stone location, a family history of stone disease, a past history of certain medical diseases and a semiquantitative estimate of the magnesium intake in food, 'over the counter' drugs and drinking water. An equivalent number of patients attending the same institutions for follow-up and verified from hospital records as having a previous radiological diagnosis of urinary tract stones, as well as a group of asymptomatic members of the community working in the same area, underwent the same interview. Chi-square, anova and Kruskal-Wallis tests were used to examine differences between the groups. Multiple logistic regression analysis was used to determine persistence of the significance of these differences after controlling for confounding variables. RESULTS: Data sufficient for analysis were obtained for 122 previous and 102 prospective patients and 102 controls. The mean age of the patients was 32 years. The ratio of males to females was 0.9-1.8:1 for the affected groups, but significantly more males than females had calculi in the lower urinary tract (19%vs. 6%; P = 0.004). More patients (30%) than controls (7%) gave a positive family history of urinary tract stone disease (P < 0.001). Affected persons had a lower dietary magnesium intake (P = 0.003), which accounted for a significantly lower total magnesium intake (P = 0.02). Logistic regression analysis of the variables studied indicated that independent predictors of the disease were a positive family history (P = 0.001), total magnesium intake (P = 0.001) and age (P < 0.001). CONCLUSION: A low magnesium intake and a positive family history are highly predictive of urinary tract calculi in this population. (+info)
Multiple mating and sequential mate choice in guppies: females trade up.
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The trade-up hypothesis outlines a behavioural strategy that females could use to maximize the genetic benefits to their offspring. The hypothesis proposes that females should be more willing to accept a mate when the new male encountered is a superior genetic source to previous mates. We provide a direct test of the trade-up hypothesis using guppies (Poecilia reticulata), and evaluate both behavioural and paternity data. Virgin female guppies were presented sequentially with two males of varying attractiveness, and their responsiveness to each male was quantified. Male attractiveness (ornamentation) was scored as the amount of orange coloration on their body. Females were generally less responsive to second-encountered males, yet responsiveness to second males was an increasing function of male ornamentation. These attractive second males also sired a greater proportion of the offspring. There was an overall tendency for last-male advantage in paternity, and this advantage was most exaggerated when the second male was more ornamented than the first. Finally, we found that our estimate of relative sperm number did not account for any significant variation in paternity. Our results suggest that female guppies may use pre-copulatory mechanisms to maximize the genetic quality of their offspring. (+info)
Food insecurity, food choices, and body mass index in adults: nutrition transition in Trinidad and Tobago.
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BACKGROUND: This study evaluated whether food insecurity and obesity were associated in a population sample in Trinidad. METHODS: A sample was drawn of 15 clusters of households, in north central Trinidad. Resident adults were enumerated. A questionnaire was administered including the short form Household Food Security Scale (HFSS). Heights and weights were measured. Analyses were adjusted for age, sex, and ethnic group. RESULTS: Data were analysed for 531/631 (84%) of eligible respondents including 241 men and 290 women with a mean age of 47 (range 24-89) years. Overall, 134 (25%) of subjects were classified as food insecure. Food insecurity was associated with lower household incomes and physical disability. Food insecure subjects were less likely to eat fruit (food insecure 40%, food secure 55%; adjusted odds ratio [OR] = 0.60, 95% CI: 0.36-0.99, P = 0.045) or green vegetables or salads (food insecure 28%, food secure 51%; adjusted OR = 0.46, 95% CI: 0.27-0.79, P = 0.005) on >/=5-6 days per week. Body mass index (BMI) was available for 467 (74%) subjects of whom 41 (9%) had BMI <20 kg/m(2), 157 (34%) had BMI 25-29 kg/m(2), and 120 (26%) had BMI >/=30 kg/m(2). Underweight (OR = 3.21, 95% CI: 1.17-8.81) was associated with food insecurity, but obesity was not (OR = 1.08, 95% CI: 0.55-2.12). CONCLUSIONS: Food insecurity was frequent at all levels of BMI and was associated with lower consumption of fruit and vegetables. Food insecurity was associated with underweight but not with present obesity. (+info)
Morphological and enzymatic correlates of aerobic and burst performance in different populations of Trinidadian guppies Poecilia reticulata.
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We examined the mechanistic basis for two whole-animal performance traits, aerobic capacity and burst speed, in six laboratory-reared Trinidadian guppy populations from different native drainages with contrasting levels of predation. Using within- and between-population variation, we tested whether variation in organs and organ systems (heart, gill and swimming motor mass) and the activities of several enzymes that support locomotion (citrate synthetase, lactate dehydrogenase and myofibrillar ATPase) are correlated with aerobic performance (maximum rates of oxygen consumption, (O(2)max)) or burst performance (maximum swim speed during escape responses). We also tested for associations between physiological traits and habitat type (different drainages and predation levels). Organ size and enzyme activities showed substantial size-independent variation, and both performance measures were strongly correlated to body size. After accounting for size effects, neither burst nor aerobic performance was strongly correlated to any organ size or enzymatic variable, or to each other. Two principal components (PCI, PC2) in both males and females accounted for most of the variance in the organ size and enzymatic variables. In both sexes, heart and gill mass tended to covary and were negatively associated with citrate synthetase and lactate dehydrogenase activity. In males (but not females), variation in aerobic performance was weakly but significantly correlated to variation in PC1, suggesting that heart and gill mass scale positively with (O(2)max). Neither of the component variables and no single morphological or enzymatic trait was correlated to burst speed in either sex. Evolutionary changes in important life history traits occur rapidly in guppy populations subjected to different predation intensities (high mortality in downstream sites inhabited by large predatory fish; low mortality in upstream sites lacking large predators). We found significant differences between stream drainages in all morphological variables and most enzymatic variables, but only the mass of the swimming motor and LDH activity were significantly affected by predation regime. Overall, our data show that microevolution has occurred in the physiological foundations of locomotor performance in guppies, but evolutionary changes in physiology do not closely correspond to the predation-induced changes in life history parameters. (+info)
Mechanisms of homing in the fiddler crab Uca rapax. 1. Spatial and temporal characteristics of a system of small-scale navigation.
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Fiddler crabs Uca rapax are central-place foragers, making feeding excursions of up to 2 m from their burrows. We describe the natural feeding excursions of path-integrating fiddler crabs and analyze their paths for signs of significant systematic or random navigation errors. No signs of any systematic errors are evident. Random errors are small, probably due to a combination of the short length and low sinuosity of the foraging paths, as well as the fiddler crabs' unique method of locomotion that allows them to remain oriented to their burrows throughout the foraging path and to minimize large body turns. We further examined the extent to which their body orientation during foraging (transverse body axis pointing more or less towards home) accurately represented their stored home vector. By examining sequences of fast escape, we have shown that crabs can correct for deviations of their transverse body axis from home during their escape path. Thus their stored home vector is independent of their moment-to-moment body orientation. Crabs were subjected to passive translational displacements and barrier obstructions. Responses to translational displacements were identical to those observed by previous authors, namely that crabs returned in the correct egocentric direction and distance as though no displacement had occurred. Covering the burrow entrance resulted in crabs returning to the correct position of the burrow, and then beginning to search. When a barrier was placed between foraging crabs and their burrow, crabs oriented their bodies toward the burrow as accurately as with no barrier. (+info)
Mechanisms of homing in the fiddler crab Uca rapax. 2. Information sources and frame of reference for a path integration system.
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Fiddler crabs Uca rapax are central-place foragers, making feeding excursions of up to several meters from their burrows. This study investigates the sources of directional and distance information used by these crabs when returning to their burrows. We tested the spatial frame of reference (egocentric or exocentric), and the source of spatial information (idiothetic or allothetic) used during homing. We also tested which components of their locomotion they integrated (only voluntary, or voluntary plus reflexive). Fiddler crabs in their natural mudflat habitat were passively rotated during normal foraging behavior using experimenter-controlled disks, before they returned home. Crabs resisted passive rotations on the disk by counter-rotating when the disk turned, which was a compensatory response to unintended movement. Crabs were usually situated eccentrically on the disk, and therefore were also subjected to a translation when the disk rotated. No crab actively compensated for this translation. Crabs that fully compensated for disk rotation made no directional homing error. Crabs that did not fully compensate homed in a direction that reflected their new body orientation. In other words, if we succeeded in reorienting a crab (i.e. it undercompensated for disk rotation), its homing error was equal to the angle by which it had been reoriented, regardless of the magnitude of the optomotor compensation. Computer-modelled crabs, each equipped with a path integrator utilizing different combinations of external (allothetic) and path-related (idiothetic) input, traversed the digitized paths of the real crabs. The home vector computed by the model crab was then compared to the homing direction observed in the real crab. The model home vector that most closely matched that of the real crab was taken to comprise the path integration mechanism employed by fiddler crabs. The model that best matched the real crab gained direction and distance idiothetically (from internal sources such as proprioceptors), and integrated only voluntary locomotory information. Crabs were also made to run home across a patch of wet acetate, on which they slipped and were thus forced to take more steps on the homeward path than theoretically required by the home vector. Crabs whose running velocity across the patch was unusually low also stopped short of their burrow before finding it. Crabs whose running velocity was not impeded by the patch did not stop short, but ran straight to the burrow entrance, as did control crabs that ran home with no slippery patch. We interpret this to mean that the velocity of some crabs was impeded because of slipping, and these therefore stopped short of their burrow after having run out their homing vector. This is positive evidence in support of the hypothesis that path integration is mediated either by leg proprioceptors or by efferent commands, but our data do not allow us to distinguish between these two possibilities. (+info)
Elevated seroprevalence of human herpesvirus 8 among men with prostate cancer.
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Background. To investigate any epidemiological association between human herpesvirus (HHV)-8 and prostate cancer, we determined the prevalence of HHV-8 seropositivity among prostate cancer case and control subjects in the United States and Trinidad and Tobago.Methods. Antibodies against HHV-8 were detected in 2 independent laboratories using either indirect immunofluorescence assay (IFA) or a combination of enzyme-linked immunosorbent assay and IFA.Results. Among 138 Tobago men with prostate cancer, HHV-8 seroprevalence was 39.9%-significantly higher than that among 140 age-matched control subjects (22.9%; P=.003; odds ratio [OR], 2.24; 95% confidence interval [CI], 1.29-3.90). Among 100 US men with prostate cancer, seroprevalence was 20%-significantly higher than that of 177 blood donors (5.1%; P=.001; OR, 4.67; 95% CI, 1.91-11.65) and higher than that of 99 men with cancer not related to HHV-8 (13%; P=.253; 95% CI, 0.77-3.54).Conclusions. HHV-8 seropositivity is elevated among men with prostate cancer compared with control subjects, which suggests that HHV-8 plays a role in the development of prostate cancer. (+info)