A genetic analysis of epistaxis as associated with EIPH in the Southern African Thoroughbred

Pedigree and race run data from Thoroughbreds racing in Southern Africa, covering the period 1986-2002 (63 146 horses in pedigree data-set and 778 532 race runs), were analysed in order to study genetic and environmental factors affecting the incidence of epistaxis as associated with \"exercise-induced pulmonary haemorrhage\" (EIPH). Variables that were tested as significant in preliminary data analyses were included as fixed effects for the model. Various combinations of such variables namely age, weight, altitude, sex, month and going were tested. Fixed effects that were included in the final model were gender, going and altitude. The heritability estimates from a logit transformed analysis for epistaxis fitting both the animal and sire models were 0.23 and 0.40, respectively, which indicated that epistaxis as associated with EIPH in Southern African Thoroughbred sires has a strong genetic basis. Genetic trends indicating an increase in epistaxis were also found. Affected stallions and those racing whilst being treated with furosemide should be barred from breeding and not be considered as future sires. Estimated breeding values for epistaxis should be used as a tool for selecting against it and be considered in breeding programmes to decrease the incidence thereof. Key Words: Estimated breeding value, Genetic factors, Heritability, Racehorse, Thoroughbred South African Journal of Animal Science Vol.34(4) 2004: 265-27

Genetic variance components for residual feed intake and feed conversion ratio and their correlations with other production traits in beef bulls

Feeding costs of animals is a major determinant of profitability in livestock production enterprises. Genetic selection to improve feed efficiency aims to reduce feeding cost in beef cattle and thereby improve profitability. This study estimated genetic (co)variances between weaning weight and other production, reproduction and efficiency traits. Traits included residual feed intake (RFI), feed conversion ration (FCR), growth (average daily gain (ADG), weaning weight (WW) and shoulder height (SHD)), reproductive (scrotum circumference (SCR)) and profitability traits measured in growth tests of young bulls. The only genetic correlations of significance with WW were those with SHD (0.50) and ADG (0.28). Weaning weight serves as no indication of an animal's production, owing to low genetic correlations with other traits (reproduction or feedlot post-weaning growth efficiency). The heritability estimated for FCR was 0.34 and for RFI 0.31 with a genetic correlation estimate of 0.75 between them. The estimated genetic correlation of profitability (Rand-value) with FCR and RFI were -0.92 and -0.59, respectively. The genetic correlations and expected correlated responses between RFI and FCR with Rand-value suggest that indirect selection for Rand-value through direct selection for FCR and/or RFI will result in slower genetic progress in Rand-value than direct selection. However, where the Rand-value cannot be calculated and/or direct selection for Rand-value is not possible, it would be better to select indirectly for Rand-value through the use of FCR rather than RFI. Key Words: Beef cattle, Feed conversion ratio, Genetic (co)variances, Profitability, Residual feed intake South African Journal of Animal Science Vol.34(4) 2004: 257-26

Genetic relationship between feed efficiency and profitability traits in beef cattle

Genetic selection to improve feed efficiency aims to reduce the cost of feeding costs in beef cattle production and thereby improve profitability. The aim of this study was to estimate genetic (co)variances to compare residual feed intake (RFI) and feed conversion ratio (FCR) with growth, reproductive and profitability traits measured in growth tests of young bulls. The heritability estimated for FCR was 0.34 and for RFI 0.31 with a genetic correlation estimate of 0.75 between the traits. The estimated genetic correlation between profitability and FCR and RFI were -0.92 and -0.59, respectively. The genetic correlations and expected correlated responses between RFI and FCR with post-wean profitability (M-value) suggest that indirect selection for M-value through the direct selection for FCR and/or RFI will result in slower genetic progress in M-value than direct selection for M-value. However, where the M-value cannot be calculated and/or direct selection for M-value is not possible, it would be better to select indirectly for M-value through the use of FCR rather than RFI. South African Journal of Animal Science Supp 2 2004: 50-5

The effect of Charolais and Hereford sires and straightbred and crossbred dams on pre-weaning growth of calves

Weaning performance of calves sired by Charolais and Hereford on dams of Angus, Bonsmara and Hereford and various crossbred dam combinations was compared. Charolais sired calves were on average 5 kg heavier at birth and 20 kg heavier at weaning than Hereford sired calves. Among the three straightbred dam breeds, the Bonsmara weaned calves that were approximately 6% heavier than both the Angus and the Hereford calves. The use of crossbred dams having intermediate levels of Charolais composition is suggested in crossbreeding programmes in intensive production systems based on cultivated pastures under irrigation. South African Journal of Animal Science Vol.32(1) 2002: 38-4

Genetic parameters and trends for birth weight, birth coat score and weaning weight in Merino lines divergently selected for ewe multiple rearing ability

Data were recorded for birth weight, birth coat score and weaning weight of between 2018 and 4235 Merino lambs born over a 17-year interval from 1986 to 2002. The resource population was divergently selected from the same base population since 1986, either for (H line) or against (L line) maternal multiple rearing ability. Direct additive genetic variances - expressed as a ratio of the total phenotypic variance (h2, direct heritability) - were estimated at 0.12 + 0.03 for birth weight, 0.70 + 0.05 for birth coat score and 0.13 + 0.04 for weaning weight. Maternal genetic variance ratios (m2) were estimated at 0.23 + 0.04 for birth weight and 0.10 + 0.04 for weaning weight. It was not significant for birth coat score. Maternal permanent environmental variance ratios (c2) for the respective traits amounted to 0.08 + 0.03 for birth weight, 0.04 + 0.02 for birth coat score and 0.08 + 0.03 for weaning weight. No consistent phenotypic or genetic differences in favour of either line were found for birth weight or birth coat score. Compared to L line lambs, phenotypic means for weaning weight were heavier in favour of H line lambs from 1995. This trend was confirmed by divergence in yearly averaged direct breeding values in the H and L lines. Expressed as percentage of the overall phenotypic mean for weaning weight, genetic changes amounted to +0.23% in the H line and -0.26% in the L line. A corresponding maternal genetic trend amounting to -0.19% of the overall phenotypic mean for weaning weight was found in the L line, while no maternal genetic change could be discerned in the H line. Divergent selection for multiple rearing ability thus did not influence birth weight and birth coat score, while the correlated response in weaning weight was favourable. Keywords: Direct heritability, Genetic trends, Maternal heritability, Parameter estimation, Smoothing splines South African Journal of Animal Science Vol.33(4) 2003: 248-25

Dexamethasone and Long-Term Outcome of Tuberculous Meningitis in Vietnamese Adults and Adolescents

BACKGROUND: Dexamethasone has been shown to reduce mortality in patients with tuberculous meningitis but the long-term outcome of the disease is unknown. METHODS: Vietnamese adults and adolescents with tuberculous meningitis recruited to a randomised, double-blind, placebo-controlled trial of adjunctive dexamethasone were followed-up at five years, to determine the effect of dexamethasone on long-term survival and neurological disability. RESULTS: 545 patients were randomised to receive either dexamethasone (274 patients) or placebo (271 patients). 50 patients (9.2%) were lost to follow-up at five years. In all patients two-year survival, probabilities tended to be higher in the dexamethasone arm (0.63 versus 0.55; p = 0.07) but five-year survival rates were similar (0.54 versus 0.51, p = 0.51) in both groups. In patients with grade 1 TBM, but not with grade 2 or grade 3 TBM, the benefit of dexamethasone treatment tended to persist over time (five-year survival probabilities 0.69 versus 0.55, p = 0.07) but there was no conclusive evidence of treatment effect heterogeneity by TBM grade (p = 0.36). The dexamethasone group had a similar proportion of severely disabled patients among survivors at five years as the placebo group (17/128, 13.2% vs. 17/116, 14.7%) and there was no significant association between dexamethasone treatment and disability status at five years (p = 0.32). CONCLUSIONS: Adjunctive dexamethasone appears to improve the probability of survival in patients with TBM, until at least two years of follow-up. We could not demonstrate a five-year survival benefit of dexamethasone treatment which may be confined to patients with grade 1 TBM. TRIAL REGISTRATION: ClinicalTrials.gov NCT01317654

The plausibility of a role for mercury in the etiology of autism: a cellular perspective

Autism is defined by a behavioral set of stereotypic and repetitious behavioral patterns in combination with social and communication deficits. There is emerging evidence supporting the hypothesis that autism may result from a combination of genetic susceptibility and exposure to environmental toxins at critical moments in development. Mercury (Hg) is recognized as a ubiquitous environmental neurotoxin and there is mounting evidence linking it to neurodevelopmental disorders, including autism. Of course, the evidence is not derived from experimental trials with humans but rather from methods focusing on biomarkers of Hg damage, measurements of Hg exposure, epidemiological data, and animal studies. For ethical reasons, controlled Hg exposure in humans will never be conducted. Therefore, to properly evaluate the Hg-autism etiological hypothesis, it is essential to first establish the biological plausibility of the hypothesis. This review examines the plausibility of Hg as the primary etiological agent driving the cellular mechanisms by which Hg-induced neurotoxicity may result in the physiological attributes of autism. Key areas of focus include: (1) route and cellular mechanisms of Hg exposure in autism; (2) current research and examples of possible genetic variables that are linked to both Hg sensitivity and autism; (3) the role Hg may play as an environmental toxin fueling the oxidative stress found in autism; (4) role of mitochondrial dysfunction; and (5) possible role of Hg in abnormal neuroexcitory and excitotoxity that may play a role in the immune dysregulation found in autism. Future research directions that would assist in addressing the gaps in our knowledge are proposed

Correlated Genetic and Ecological Diversification in a Widespread Southern African Horseshoe Bat

The analysis of molecular data within a historical biogeographical framework, coupled with ecological characteristics can provide insight into the processes driving diversification. Here we assess the genetic and ecological diversity within a widespread horseshoe bat Rhinolophus clivosus sensu lato with specific emphasis on the southern African representatives which, although not currently recognized, were previously described as a separate species R. geoffroyi comprising four subspecies. Sequence divergence estimates of the mtDNA control region show that the southern African representatives of R. clivosus s.l. are as distinct from samples further north in Africa than they are from R. ferrumequinum, the sister-species to R. clivosus. Within South Africa, five genetically supported geographic groups exist and these groups are corroborated by echolocation and wing morphology data. The groups loosely correspond to the distributions of the previously defined subspecies and Maxent modelling shows a strong correlation between the detected groups and ecoregions. Based on molecular clock calibrations, it is evident that climatic cycling and related vegetation changes during the Quaternary may have facilitated diversification both genetically and ecologically

Dietary meat and fat intake and prevalence of rhinoconjunctivitis in pregnant Japanese women: baseline data from the Kyushu Okinawa Maternal and Child Health Study

<p>Abstract</p> <p>Background</p> <p>Dietary fat exerts numerous complex effects on proinflammatory and immunologic pathways. Several epidemiological studies have examined the relationships between intake of fatty acids and/or foods high in fat and allergic rhinitis, but have provided conflicting findings. The current cross-sectional study investigated such relationships in Japan.</p> <p>Methods</p> <p>Study subjects were 1745 pregnant women. The definition of rhinoconjunctivitis was based on criteria from the International Study of Asthma and Allergies in Childhood. Information on dietary factors was collected using a validated self-administered diet history questionnaire. Adjustment was made for age; gestation; region of residence; number of older siblings; number of children; smoking; secondhand smoke exposure at home and at work; family history of asthma, atopic eczema, and allergic rhinitis; household income; education; and body mass index.</p> <p>Results</p> <p>The prevalence of rhinoconjunctivitis in the past 12 months was 25.9%. Higher meat intake was significantly associated with an increased prevalence of rhinoconjunctivitis: the adjusted odds ratio between extreme quartiles was 1.71 (95% confidence interval: 1.25-2.35, <it>P </it>for trend = 0.002). No measurable association was found between fish intake and rhinoconjunctivitis. Intake of total fat, saturated fatty acids, monounsaturated fatty acids, n-3 polyunsaturated fatty acids, α-linolenic acid, eicosapentaenoic acid, docosahexaenoic acid, n-6 polyunsaturated fatty acids, linoleic acid, arachidonic acid, and cholesterol and the ratio of n-3 to n-6 polyunsaturated fatty acid intake were not evidently related to the prevalence of rhinoconjunctivitis.</p> <p>Conclusions</p> <p>The current results suggest that meat intake may be positively associated with the prevalence of rhinoconjunctivitis in young adult Japanese women.</p

Childhood tuberculosis is associated with decreased abundance of T cell gene transcripts and impaired T cell function

The WHO estimates around a million children contract tuberculosis (TB) annually with over 80 000 deaths from dissemination of infection outside of the lungs. The insidious onset and association with skin test anergy suggests failure of the immune system to both recognise and respond to infection. To understand the immune mechanisms, we studied genome-wide whole blood RNA expression in children with TB meningitis (TBM). Findings were validated in a second cohort of children with TBM and pulmonary TB (PTB), and functional T-cell responses studied in a third cohort of children with TBM, other extrapulmonary TB (EPTB) and PTB. The predominant RNA transcriptional response in children with TBM was decreased abundance of multiple genes, with 140/204 (68%) of all differentially regulated genes showing reduced abundance compared to healthy controls. Findings were validated in a second cohort with concordance of the direction of differential expression in both TBM (r2 = 0.78 p = 2x10-16) and PTB patients (r2 = 0.71 p = 2x10-16) when compared to a second group of healthy controls. Although the direction of expression of these significant genes was similar in the PTB patients, the magnitude of differential transcript abundance was less in PTB than in TBM. The majority of genes were involved in activation of leucocytes (p = 2.67E-11) and T-cell receptor signalling (p = 6.56E-07). Less abundant gene expression in immune cells was associated with a functional defect in T-cell proliferation that recovered after full TB treatment (p<0.0003). Multiple genes involved in T-cell activation show decreased abundance in children with acute TB, who also have impaired functional T-cell responses. Our data suggest that childhood TB is associated with an acquired immune defect, potentially resulting in failure to contain the pathogen. Elucidation of the mechanism causing the immune paresis may identify new treatment and prevention strategies