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Biomedical subjects

M C Roberts

Publications and source records attributed to M C Roberts.

At least 235 records · Page 13Linked to original sources

Granulomatous enteritis in a young standardbred mare.

Granulomatous enteritis was diagnosed in a 4-year-old Standarbred mare suffering from chronic weight loss, depression, dependent oedema but not diarrhoea. There was hypoproteinaemia (hypoalbuminaemia), lymphocytopaenia and neglibible carbohydrate absorption from the small intestine. Pathological changes in almost the entire small intestine included proprial infiltration resulting in partial villous atrophy, and granuloma formation beneath the muscularis which was most severe in the ileum. Slight infiltration occurred in the stomach and the colon. The cells were predominantly lymphocytes and histocytes. No acid-fast organisms were found.

Animals↗

Characterization of chloramphenicol-resistant Haemophilus influenzae.

We examined nine chloramphenicol-resistant (minimal inhibitory concentration, greater than or equal to 15 micrograms/ml) Haemophilus influenzae strains isolated in various parts of the world to characterize the genetic and biochemical bases of the resistance; four were type b. All nine contained conjugative plasmids, ranging in molecular weight from 34 x 10(6) to 46 x 10(6), which encoded for resistance to chloramphenicol and tetracycline or chloramphenicol, tetracycline, and ampicillin. Deoxyribonucleic acid homology studies showed that these plasmids were closely related to a previously described ampicillin-resistant plasmid, RSF007, and to each other. All nine isolates and their chloramphenicol-resistant transconjugants produced chloramphenicol acetyltransferase. We conclude that chloramphenicol resistance in these strains of H. influenzae is via plasmid-mediated production of chloramphenicol acetyltransferase.

Acetyltransferases↗

Molecular characterization of "plasmid-free" antibiotic-resistant Haemophilus influenzae.

We examined 14 multiresistant and 8 ampicillin- or tetracycline-resistant Haemophilus influenzae isolates and 4 ampicillin-resistant H. parainfluenzae isolates for plasmid deoxyribonucleic acid. Sixteen strains carried plasmids. Both "plasmid-free" and plasmid-carrying isolates transferred the antibiotic resistance by conjugation. All transconjugants carried plasmid deoxyribonucleic acid, suggesting that the apparent plasmid-free strains contained R plasmids encoding for antibiotic resistance.

Ampicillin↗

Ascending urinary tract infection in ponies.

Two young ponies had the prescrotal portion of their penises accidentally amputated during castration. They both developed ascending urinary tract infections over the next 4 weeks. One pony had a necrotising cystitis and pyelonephritis, the other improved markedly after a urethrostomy had been performed but was destroyed several months later.

Animals↗

A re-evaluation of the D (+) xylose absorption test in the horse.

The absorption of d-xylose forms the basis of a useful screening test in the investigation of small intestinal disorders in the horse. A comparison has been made of different assay methods and there was no significant difference between the results obtained with the parabromoaniline (PBA) method or the ferric chloride-orcinol (FCO) method. The orthotoluidine method was unsatisfactory. The anticoagulant agent did not affect the test. A dose of 0.5 g commercial grade xylose/kg body weight as a 10 per cent solution given by stomach tube, produced a peak plasma xylose level after 90 min and should discriminate normal from abnormal absorption. The FCO method was preferred for the occasional test performed in practice, and a 2-hour sampling period would be adequate.

Aniline Compounds↗

Chronic phenylmercuric acetate toxicity in a horse.

Phenylmercuric acetate (PMA) was administered orally to a horse over a period of 27 weeks (190 days) at a dose rate of 0.4 mg Hg/kg per day. The effects produced were consistent with those of chronic inorganic mercury intoxication. The clinical features included masseter muscle atrophy, difficulty in prehension and mastication, malodorous breath, reduced appetite and weight loss, and reflected significant pathological changes involving the buccal, mandibular and dental tissues. Renal dysfunction was evident terminally and there was degeration and necrosis of the proximal tubular epithelium. Necrotic and mineralized foci were found in facial and masticatory msucles, splenic trabecuale and the myocardium. The central nervous system and the intestinal tract were unaffected. The approximate mean plasma inorganic mercury concentration was 500 ng/ml whereas organic mercury levels in blood were much lower. The renal cortex had the highest inorganic mercury content, three times greater than in the liver and cecum, while organic mercury was highest in those tissues and absent from the kidney. The difference in the effects produced in this horse as compared to those in a horse receiving mercuric chloride at the same mercury dose rate, could be attributed to the more rapid and complete absorption of PMA from the gastrointestinal tract.

Animals↗

Dermatological manifestations in psoriatic arthritis: a follow-up study.

Of 227 patients with psoriasis and rheumatic complaints, inflammatory arthritis was present in 168 patients, of whom 95 have been followed up for more than 5 years and 28 had been followed up for more than 10 years. In patients with psoriasis and inflammatory arthritis the majority were women, but in the Distal joint group, males predominated. The skin disease usually began on the arms and was restricted in extent, initially. It usually began before the arthritis. A few cases were apparently precipitated by trauma, but more by psychological factors. The course pursued by the skin lesions was generally favourable. The skin lesions were resistant to treatment in 20% of the patients. Puberty, pregnancy and the menopause had little effect on the skin lesions. Nail lesions were present in 80%, a greater frequency than that seen in uncomplicated psoriasis. These nail lesions began at a later age than the skin lesions, and commonly preceded the development of arthritis. There was a family history of psoriasis in 26% of first-degree relatives. A history of polyarthritis was obtained quite frequently, and of psoriatic arthritis in 3% of patients with Distal arthritis, and 2% of the Indistinguishable group. The arthritis was usually mild in degree. Ankylosing spondylitis occurred in 5% and sacro-iliitis in 19%. The sheep cell agglutination test for rheumatoid factor was negative in the majority of patients. It was positive in 16% and a fluctuating positive result was obtained in 10%.

Adolescent↗

Splenectomy in the horse.

Splenectomy was successfully performed on 2 aged horses to facilitate experimental studies of Babesia equi infection. Resection of part of the 17th rib provided the most acceptable approach and avoided many complications encountered on removing part of the 16th rib.

Animals↗

Ameloblastic ondontoma in a foal.

A 4 month old foal with right sided maxillary enlargement and considerable upper airway obstruction had an ameloblastic odontoma in the right maxillary sinus. This odontogenic tumour, probably congenital in nature, had extensively distorted the structure and contours of the sinus, and displaced the adjacent turbinates and nasal septum.

Airway Obstruction↗

The identification of Babesia equi in Australia.

A Babesia parasite, isolated from the blood of a horse at Bowral, New South Wales, was identified on the basis of its morphological features, host specificity and serological reactions, as Babesia equi (Laveran 1901). The case was originally reported by Churchill and Best (1976, Aust. vet. J. 52: 487) and is the first record of equine babesiosis in Australia. In preliminary studies, the organism produced only a mild disease in an intact horse, but caused the typical clinical syndrome of acute babesiosis in a splenectomised horse, which died 19 days after the intravenous inoculation of the parasites.

Animals↗

A case of primary lymphoid leukaemia in a horse.

Progressive leukaemic changes and a persistent anaemia were demonstrated in the blood of a 7 year old gelding, which had shown early signs of lowered performance and unthriftiness, and later developed dependent oedema and became dull and listless. The total leucocyte count, initially within the normal range although reflecting an absolute lymphocytosis, increased fourfold in 6 days from excessive lymphoid production involving predominantly the more immature cell types; lymphoblasts, prolymphocytes and large lymphocytes. The severity of the condition was confirmed by bone marrow biopsy.

Animals↗