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Biomedical subjects

M C Roberts

Publications and source records attributed to M C Roberts.

At least 217 records · Page 12Linked to original sources
PubMed1983

Experiments to increase return in a medical screening drive: two futile attempts to apply theory to practice.

Two experiments are reported which attempted to apply techniques derived from an extensive set of psychological theories and research to enhance return compliance in a tuberculosis detection drive. Experiment 1 manipulated four methods of providing return reminders (postcard, telephone call, direct person-to-person or take-home card) in combination with two types of authority sources (expert vs nonexpert). Experiment 2 manipulated types of patient commitment (verbal, verbal plus written or no commitment) and importance-or-returning message (enhanced vs standard) in combination with two types of return reminders (take-home card vs no reminder card). These theoretically-derived procedures failed to significantly enhance return compliance. The experiments are examined for procedural failures and the findings are discussed in terms of the limited applicability of some theoretical notions in health settings and particular populations. It is asserted that through such failures useful knowledge is gained for understanding the complex phenomenon of compliance.

Adult↗
PubMed1983

Serum and red cell folate and serum vitamin B12 levels in horses.

Vitamin B12 and folate concentrations were determined by radioimmunoassay in groups of horses in Queensland. Highest serum vitamin B12 levels were found in supplemented performance horses. These, together with pastured horses that included pregnant and lactating mares, had significantly greater serum folate activity than permanently stabled animals. The range of red cell folate concentrations was much narrower in horses in training than from any other group. Red cell folate may be a better indicator of a horse's folate status than the serum folate value. Vitamin B12 and folate concentrations were highest in spring and summer. Small intestinal dysfunction in 2 horses was not associated with vitamin B12 or folate malabsorption. Serum folate levels returned to normal 24 h after intramuscular injections of 75 to 150 mg folic acid, whereas serum vitamin B12 values remained elevated for at least one week following injections of 8 to 10 mg to non-supplemented horses. None of the horses in this survey had evidence of vitamin B12 or folate deficiency, or showed significant haematological changes. Nevertheless, permanently stabled horses and some horses in training may require additional folic acid, preferably on a daily basis by the oral route. However, exogenous vitamin B12 administration does not appear to be justified.

Animals↗
PubMed1983

Experimental studies of drug-induced impaction colic in the horse.

Colic was induced in horses and ponies following topical or intravenous (iv) administration of amitraz, a formamidine acaricide. The condition was characterised by rapid cessation of intestinal sounds, stasis, extensive impaction and tympany throughout the large colon. Three animals that were necropsied had a faecalith obstructing the proximal small colon aboral to marked colonic impaction. A reproducible and reversible impaction colic syndrome could be induced by an iv injection of 1 mg amitraz/kg body weight in solvent. There were immediate central nervous system and intestinal signs. Large intestinal contents dried out rapidly, possibly indicating enhanced fluid absorption. The effects could be attributed to amitraz rather than to one of its known metabolites and was not shown by other formamidines. The action of amitraz in the horse is unclear. It could involve the mediation of neuromodulators (from the intrinsic enteric nervous system) which affect the coordination of myoelectrical activity from putative pacemaker regions in the large intestine and, possibly, fluid and ion transport. Naturally occurring impaction colic could have a similar pathogenesis. Drug-induced impaction colic might provide a unique model for studying the pathophysiology of impaired motor activity and ion transport in the equine large intestine.

Aerosols↗
PubMed1982

Renal dysfunction in a case of purpura haemorrhagica in a horse.

A four-year-old thoroughbred was presented with clinical manifestations of purpura haemorrhagica. Evidence of renal involvement consistent with glomerulopathy and nephrotic syndrome, characterised by heavy proteinuria and azotaemia, became apparent and may have been exacerbated by diuretic therapy. Autopsy revealed membrano- and mesangial proliferative glomerulonephritis and chronic pleuritis. Circulating immune complexes may have been responsible for the renal diseases and the purpura.

Animals↗
PubMed1982

Experimental Salmonella anatum infection in horses.

Salmonella anatum was given orally to 8 horses on 11 occasions in doses ranging from 9.5 X 10(6) to 8.8 X 10(11) organisms. Four distinct syndromes were induced based upon clinical, laboratory and pathological findings: (1) asymptomatic; (2) moderate clinical signs with or without changes in faecal consistency; (3) fever, depression, anorexia with unstructured or diarrhoeic faeces; and (4) septicaemia with or without diarrhoea, and peripheral circulatory failure. All animals excreted the organism. The peak temperature preceded the onset of diarrhoea by 1 or 2 days. Changes in faecal consistency were associated with direct isolation of the organism. The degree of neutropaenia increased with the dosage. Blood cultures were unsatisfactory, only 1 of 33 samples being positive. The serological responses were not significant although one animal displayed a significant seroconversion consistent with the clinical reaction. Indomethacin was not of value in moderating intestinal fluid secretion in one animal. The distribution and quantitation of positive cultures at autopsy closely reflected the type of syndrome induced. The invasiveness of the organism was confirmed by frequent direct recoveries from intestinal wall and draining lymph node samples. S. anatum appears to be of similar pathogenicity to S. typhimurium in the horse, at least under experimental conditions.

Agglutination Tests↗
PubMed1982

Characterization of ampicillin-resistant Haemophilus parainfluenzae.

Carriage of ampicillin-resistant (Ampr) Haemophilus parainfluenzae has become frequent among children in our community, although carriage of Ampr Haemophilus influenzae remains uncommon. In this study we characterized the mechanism of ampicillin resistance in 27 representative isolates of H. parainfluenzae. As determined by isoelectric focusing, each isolate had a TEM-1 beta-lactamase; substrate profiles assessed for enzymes from 10 strains were also consistent with TEM-1 enzyme. Agarose gel electrophoresis revealed a plasmid of 23 to 34 megadaltons in each isolate and a small plasmid (less than or equal to 4 megadaltons) in 14 isolates. Transfer of ampicillin resistance to H. influenzae Rd was achieved during membrane mating with 14 of 15 donors. The transconjugants exhibited high-level ampicillin resistance (greater than or equal to 50 micrograms/ml), which was stable despite serial passage of isolates on antibiotic-free media. The transconjugants tested retained fertility. Cryptic plasmids were discovered in 7 of 25 antibiotic-susceptible H. parainfluenzae isolates. Our data suggest that H. parainfluenzae may play an important role in the exchange of Ampr genes among throat bacteria.

Ampicillin↗
PubMed1982

Mutation frequency of Haemophilus influenzae to rifampin resistance.

Twenty-two susceptible strains of Haemophilus influenzae were examined for mutation to rifampin resistance (minimal inhibitory concentration, greater than or equal to 10 micrograms/ml). All strains had detectable apparent mutation frequencies with a median minimal inhibitory concentration 2,000-fold greater than that of their wild-type parents. Of the type b strain mutants, 80% (8 of 10) expressed high-level resistance (minimal inhibitory concentration, 750 micrograms/ml) that was 75-fold greater than readily achievable serum concentrations.

Drug Resistance, Microbial↗
PubMed1982

Some effects of chronic mercuric chloride intoxication on renal function in a horse.

Chronic mercuric chloride intoxication in an aged horse given 0.8 mg Hg/kg/day for 14 weeks was manifest by signs of progressive respiratory difficulty and renal disease. The effects were not self-limiting after mercury was withdrawn, and the animal was destroyed six weeks later. Renal function changes included heavy glycosuria, modest proteinuria, phosphaturia, reduced urine osmolality, gradually increasing urine production, reduced glomerular filtration rate, and terminally, azotemia. The condition bore similarities to the Fanconi syndrome in man. Urinary gamma-glutamyl transpeptidase, alkaline phosphatase and amino-aspartate transferase activities were inconsistent indicators of tubular damage in random samples at this dose rate. The pathologic response was characterized by extensive granulomatous infiltration throughout the lungs, in particular, and to a lesser extent in the kidneys, liver and bone marrow. The renal changes included this marked interstitial reaction and proximal tubular degeneration. Mercury levels were negligible in the lungs and highest in the renal cortex. The granulomatous reaction was not encountered in previous mercury toxicity studies in horses and may indicate an individual sensitivity to the agent.

Animals↗
PubMed1982

Hemodynamic effects of prostacyclin (prostaglandin I2) in conscious ponies.

The infusion (IV) of prostacyclin (PGI2) into conscious ponies resulted in systemic arterial hypotension and tachycardia. Mean systemic arterial pressure decreased from 103.3 mm of Hg to 88.5 mm of Hg when 125 ng of PGI2/kg/minute was infused, and heart rate increased from 55.0 to 102.0 beats/minute. When 208 ng of PGI2/kg/minute was infused, mean systemic arterial pressure decreased from 103.3 to 78.0 mm of Hg and heart rate increased from 55.0 to 109.3 beats/minute. There were no significant alterations in pulmonary arterial pressure, lactate, PCV, total WBC count, platelet count, serum lactic dehydrogenase, and acid phosphatase activities, or rectal temperature at either dosage. The ponies became anxious and difficult to manage during the infusion.

Acid Phosphatase↗
PubMed1982

Retropulsion-propulsion in equine large colon.

The circular and longitudinal muscle coats of equine "midcolon" were found to be directly electrically coupled. They appear to act in concert, in healthy animals, as a pacemaker in the area of the large colon pelvic flexure, for retropulsive-propulsive myoelectrical events. The retropulsive events keep the cecum and right ventral and left ventral divisions of the colon filled, imposing a delay time for fermentation of cellulose and for bacterial protein synthesis. Point-to-point involvement of adjacent colon sections was slowed by cooling the intestinal contents with no adverse clinical signs. Diminution of the blood flow to this regulatory area was achieved in 12 weanling foals (raised parasite-free) by parasitic cranial mesenteric arteritis, using Strongylus vulgaris larvae. Four of the 12 developed clinical signs of abdominal pain, but on necropsy 3 of these 4 had no gross lesions in the gastrointestinal tract. Dissociation of the left ventral and left dorsal colon divisions, as regards intraluminal pressure events and their antecedent myoelectrical action potentials, was induced in 7 of 8 adult animals given an acaricide which under field conditions is associated with progressive large colon obstruction and colic.

Animals↗
PubMed1981

A protracted case of cryptococcal nasal granuloma in a stallion.

A 13-year-old Standardbred stallion presented with a unilateral mucopurulent nasal discharge and airway obstruction was found to have an extensive cryptococcal nasal granuloma. Treatment was not attempted. The stallion was destroyed 26 months later having completed 2 successful breeding seasons. The granuloma had gradually increased in size and almost completely occupied the left nasal cavity and paranasal sinuses. It was characterised histologically by fibrous and myxomatous tissue and masses of yeasts. A cryptococcal granuloma found within the wall of the jejunum could represent evidence of dissemination, and organisms were seen within alveoli, bronchioles and the intestinal lumen.

Animals↗
PubMed1981

The prevalence and epizootiology of salmonellosis among groups of horses in south east Queensland.

Over a 3-year period, 1178 faecal samples were cultured from 462 horses admitted to the equine clinic of the University of Queensland; 185 samples were positive for salmonella yielding 213 isolations consisting of 21 serotypes. S. anatum was the predominant serotype isolated (54%) followed by S. ohio (11.27%) and S. typhimurium (9.4%). One hundred and ten horses (23.81%) were positive on one or more occasion, and 42 (9.09%) on more than one occasion. S. anatum was the most common serotype isolated (71.43%) from the main drains in the stable block (33.57% positive samples). The prevalence of salmonella excretors among a large non-clinic population of horses in south east Queensland was 1.65%. Acute salmonellosis did not occur in the hospitalised animals. However, salmonellas were incriminated in 6 cases of chronic diarrhoea, which all yielded S. anatum, although the most severe involved both S. anatum and S. typhimurium, and these serotypes were isolated from multiple locations at the subsequent autopsy of 3 cases.

Animal Feed↗
PubMed1980

Increasing return compliance in a tuberculosis detection drive.

This study explored the role of subject commitment as a variable for increasing compliance rates in a university-sponsored tuberculosis (TB) detection drive. Return rates for reaction readings were compared between those subjects who had made an overt commitment to return (either a verbal or a verbal plus written agreement) and those subjects who were exposed to a standardized, no commitment procedure. Return rates under both commitment conditions significantly increased. Contrary to expectation, subjects with a known family history of TB were found to be a high-risk group for noncompliance. For this group, obtaining both verbal and written agreement from subjects appeared to be the most efficacious procedure to increase compliance.

Adolescent↗