Characterization of normal tidal breathing flow-volume loops for Thoroughbred horses

The purpose of this study was to characterize the normal equine tidal breathing flow-volume loop (TBFVL). The study was performed using 18 healthy Thoroughbred horses. TBFVLs constructed from data collected from resting horses had a typical biphasic inspiratory and expiratory phase. The interindividual variability of the indices used to describe TBFVLs was in the range 16–32%, which is comparable to the variability of other measures of equine pulmonary mechanics. The large variability of these data probably limits the value of resting TBFVL indices for detecting subclinical respiratory conditions in individual horses. Factor analysis of these data revealed that in excess of 90% of the variance of the initial response variables could be explained in terms of three common factors. Varimax rotation of these three common factors provided three subsequent factors that were readily identifiable as (1) a factor describing the time-volume relationships of TBFVLs, responsible for 81% of the total variance, (2) a factor explaining the expiratory portion of the TBFVL, explaining 12% of the variance, and (3) a factor describing the inspiratory portion of the loops, responsible for the remaining 7% of the variance. The analysis also provided standardized factor scoring coefficients for use in subsequent studies using similar experimental techniques.Abbreviations EF₂₅ expiratory flow at expiratory volume plus 25%V _E - EF₅₀ midtidal expiratory flow - f respiratory rate - IF₂₅ inspiratory flow at 25% of inspiratory volume - IF₅₀ midtidal inspiratory flow - MSA measure of sampling adequacy - PEF peak expiratory flow - PIF peak inspiratory flow - TBFVL tidal breathing flow-volume loop - T _E expiratory time - T _I inspiratory time - USPTM ultrasonic pneumotachometer - V _E expiratory volume - V _I inspiratory volume     

The clinical pathology of heartwater. II. Studies on cardiac and pulmonary function in 4 calves with experimentally-induced heartwater

Studies to evaluate cardiac and pulmonary function were undertaken in 4 calves suffering from experimentally-induced heartwater. There was a marked variation in the course of the disease. Three of the calves recovered spontaneously after developing clinical signs. These included a rectal temperature in excess of 40 degrees C, anorexia and listlessness but no neurological signs. The remaining calf died 2 days after developing a fever and neurological signs. In the 3 calves that recovered, a mild hypoxemia developed during the acute stage of the disease. Arterial CO2 tension remained within normal limits, but there was a tendency towards an alkalosis. Increases in pulmonary dead space and fluctuations in venous admixture were observed. The calf that died showed similar mild changes in blood gas parameters, despite the presence of a marked reduction in minute volume, and a lung oedema was demonstrated on post-mortem examination. No marked changes in systolic and diastolic blood pressures and in right cardiac intraventricular pressures were observed. Terminally, however, there were marked decreases in stroke volume and cardiac output. These changes were associated with a sharp increase in heart rate. No primary cardiac pathology was observed on clinical and post-mortem examinations.     

In vitro metabolism of insecticides during midgut penetration

A study of the metabolism of ¹⁴C-labeled dieldrin, DDT, malathion, and carbaryl during penetration of the isolated midgut of two insects (Blaberus discoidalis and Manduca sexta) and a section of the intestine of a mammal (Mus musculus) is reported. There was appreciable metabolism of malathion during penetration, including differences in the activation reaction to malaoxon, between insects and mammals. Metabolism was relatively slow during penetration of carbaryl and the chlorinated hydrocarbon insecticides, and little difference in metabolic patterns was noted among the three species. The penetration studies were supported by experiments in which insecticides were incubated with intact and homogenized midgut preparations.     

Chemical modifications of the insecticide binding sites on human serum albumin: Role of indole,bilirubin, and fatty acid binding sites

Interaction of carbamate and organophosphorus insecticides with chemically modified human serum albumin was studied by solubilization and difference spectra of bound insecticides and quenching of albumin fluorescence. Chemical modification involved oxidation of 1 tryptophan and 4 histidine residues, acetylation of 4 tyrosine and 26 lysine residues, and reaction of 7 arginine residues with 1,2-cyclohexanedione. There was a decrease in binding due to modification of arginine, tryptophan, and tyrosine residues and an increased binding due to lysine acetylation. The presence of bilirubin and octanoate also decreased the binding of insecticides. Changes in fluorescence of bound ANS due to binding of insecticides to albumin indicate localized perturbation of albumin conformation. The binding of insecticides was not affected by palmitate at physiological concentrations (molar ratio less than 2) although higher fatty acid concentrations caused a decrease. These preliminary observations suggest that warfarin, indole, and bilirubin sites are probably among the multiple insecticide binding sites.     

Use of a radiographic scoring technique for the assessment of dogs with elbow osteochondrosis

A retrospective study was made of 335 dogs with elbow osteochondrosis that had been seen at the Royal Veterinary College in 1977 to 1987. The most commonly affected breeds were the labrador, retriever and rottweiler. Males were affected more often than females. The condition was bilateral in 50 per cent of cases and the peak age for the onset of lameness was four to six months. In rottweilers, the lesions found at exploratory arthrotomy were predominantly abnormalities of the coronoid process, while in retrievers and labradors lesions most commonly affected the medial humeral condyle or the coronoid process. A scoring system for grading the standard projection (lateral and postero-anterior) radiographs was devised and the score was correlated with the lesion found at surgery. Some cases were reviewed radiographically and any alteration in the degree of periarticular arthrosis, seen as an increase in radiographic score, was noted. The exact extent of the lesion found at surgery was recorded diagrammatically in 65 cases. It did not prove possible to predict from the radiographic score the nature and extent of the lesion and no correlation could be found between the radiographic score [and clinical degree of lameness. The scoring system did have some merit for reviewing cases because an increase in score indicated the extent to which joint changes had advanced.     

The clinical pathology of heartwater. I. Haematology and blood chemistry

Clinical pathological studies were undertaken in 5 calves with experimentally-induced heartwater. The most important findings include a progressive anaemia which may be associated with bone marrow depression and fluctuations in the total and differential white cell count, of which an eosinopenia and a lymphocytosis were the most marked. A severe drop in serum protein, especially in the albumin levels, was observed in all 5 cases. This disease is probably associated with an increased capillary permeability, as the protein content of the pericardial fluid in 1 case that died, approximated that of the serum. The osmolality of the effused fluid was also higher than that of the blood. No significant changes in the serum electrolyte levels occurred, except for total calcium levels which tended to decrease to below normal during the acute stage of the disease. Marked increases in total bilirubin were recorded. This, however, was not associated with liver pathology or haemolysis and may possibly be ascribed to a fasting hyperbilirubinaemia. Darkening of plasma colour was associated with peak rises in total bilirubin. Increases in both blood urea and creatinine levels indicate interference with renal glomerular filtration during the acute stage of the disease.     

A Selective-Differential Medium for Detection of Streptococcus Agalactiae

A practical culture medium which allows direct plating of milk samples for detection and differentiation of Streptococcus agalactiae within 48 hours is described. Most other micro-organisms likely to be present in these samples are inhibited. Although some strains of Staphylococcus species and ofStreptococcus faecalis are able to grow, they may be differentiated on the basis of reaction in the medium surrounding the colonies.