Chemoreceptor responsiveness at sea level does not predict the pulmonary pressure response to high altitude

The hypoxic ventilatory response (HVR) at sea level (SL) is moderately predictive of the change in pulmonary artery systolic pressure (PASP) to acute normobaric hypoxia. However, because of progressive changes in the chemoreflex control of breathing and acid-base balance at high altitude (HA), HVR at SL may not predict PASP at HA. We hypothesized that resting peripheral oxyhemoglobin saturation (SpO2) at HA would correlate better than HVR at SL to PASP at HA. In 20 participants at SL, we measured normobaric, isocapnic HVR (L/min·-%SpO2 -1) and resting PASP using echocardiography. Both resting SpO2 and PASP measures were repeated on day 2 (n=10), days 4-8 (n=12), and 2-3 weeks (n=8) after arrival at 5050m. These data were also collected at 5050m on life-long HA residents (Sherpa; n=21). Compared to SL, SpO2 decreased from 98.6 to 80.5% (P<0.001), while PASP increased from 21.7 to 34.0mmHg (P<0.001) after 2-3 weeks at 5050m. Isocapnic HVR at SL was not related to SpO2 or PASP at any time point at 5050m (all P>0.05). Sherpa had lower PASP (P<0.01) than lowlanders on days 4-8 despite similar SpO2. Upon correction for hematocrit, Sherpa PASP was not different from lowlanders at SL, but lower than lowlanders at all HA time points. At 5050m, whilst SpO2 was not related to PASP in lowlanders at any point (all R2=0.50), there was a weak relationship in the Sherpa (R2=0.16; P=0.07). We conclude that neither HVR at SL nor resting SpO2 at HA correlates with elevations in PASP at HA

Metatalk in American academic talk: The cases of "point" and "thing"

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/88138/1/swales-metatalk_american_academic.pd

The immunogenetics of resistance toTrichostrongylus colubriformis and Haemonchus contortus parasites in sheep

Three possible immunogenetic markers for resistance to intestinal parasitesin sheep have been studied. Allotypes of the major histocompatibility complex (MHC) of the sheep have been investigated as markers, using serological typing or gene probes, for associations between allotypes and resistance to parasites in selected high responder and low responder lines of sheep. Only the serologically-determined class I ovine leucocyte antigen (OLA) types SY 1a and SY 1b have been found to be consistently associated with increased resistance to Trichostrongylus colubriformis, but this association has not extended to the immunological distinct Haemonchus contortus parasite. Gene probes of the sheep DRB, DQB and DQA MHC class II loci have detected animals with increased susceptibility to T. colubriformis. Eosinophilia was investigated as a marker and found to be associated with increased resistance to parasites in lines of Australian Merinos and New Zealand Romneys selected for resistance on the basis of low faecal egg count. Blood eosinophilia was distinct from eosinophil infiltration of the gut which was poorly associated with resistance. The mechanism of parasite resistance appeared to involve the release of vasoactive amines and leukotrienes into intestinal mucus, since the selected high responder sheep to T. colubriformis and H. contortus had significantly increased amounts of these agents in their gut mucus, compared with selected low responder or random-bred sheep. Antibodies to T. colubriformis and H. contortus have also been used as markers to select high responder sire groups of lambs in contact with the parasites, for the first time, at weaning. This assay had the advantage of detecting distinct antigens for the two parasites, which would allow resistance to the species of parasite to be selected in the lambs. Vaccines have been developed against H. contortus using 'novel' gut antigens from the parasite, but variable responsiveness of the host sheep seemed to result in varying degrees of protection which were stimulated by these vaccines

A descriptive study of the sternal and lateral recumbency behaviour of two show horses during transportation to different environments

This study design was descriptive to discover if there was an impact on the recumbency behaviour of 2 horses during a 950-kilometre journey and 14-day stay in Sydney to compete at the Royal Easter Show

The effect of different levels of crude protein on the pathophysiology of Haemonchus contortus infection in 2-year-old Boer dry does under confined conditions

The effect of dietary protein supplementation on the pathophysiology of a single Haemonchus contortus infection in 2-year-old Boer dry does under confined conditions was examined. Twenty-four does were randomly confined in individual pens and allocated into three groups balanced by their liveweight. The goats in the Control group were offered a basal diet whereas goats in Treatments 1 and 2 were fed the basal diet plus 25% and 50% dietary protein increments, respectively. Each animal was orally administrated 100 H. contortus L3 larvae/kg liveweight on Day 0 of the experiment. The goat liveweights and FAMACHA scores were recorded at weekly intervals. Packed cell volumes, eosinophil percentage, haemoglobin concentration, total serum protein, globulin, and albumin concentrations were recorded on Days 0 and 14, and then at weekly intervals during the experiments. Faecal egg counts were measured on Days 0, 21, and then at weekly intervals thereafter. Antigen-specific IgA, IgG, and IgM titres were determined from Enzyme-linked immunosorbent assays tests on Days 0, 28, and at the termination of the experiment. The results of this study showed that a single H. contortus L3 infection did not cause pathogenic effects in 2-year-old Boer dry does. Dietary protein supplementation significantly lowered faecal egg count and significantly enhanced IgG titres (P < 0.05). However, the higher protein diets did not have any significant effects on liveweight, packed cell volumes, haemoglobin concentration, biological parameters (total serum protein, albumin, and globulin concentrations), and peripheral antibodies (IgA and IgM titres) between the treatments. Further investigations are required to clarify the role of protein supplementation to control H. contortus infection in goats