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Biomedical subjects

H Pearson

Publications and source records attributed to H Pearson.

At least 37 records · Page 2Linked to original sources
PubMed1991

Squamous cell carcinoma of the equine external genitalia: a review and assessment of penile amputation and urethrostomy as a surgical treatment.

A retrospective analysis was performed on 48 cases of suspected neoplasia involving the equine external genitalia. Forty nine squamous cell carcinomata (SCC) and 23 squamous papillomata (SP) were identified. Two cases of epithelial hyperplasia and one case of habronemiasis were also recognised histopathologically. The glans penis was the most common site of tumour development accounting for 53 per cent of cases of SCC and 61 per cent of SP. The urethral diverticulum, urethral process or urethra was involved in 27.6 per cent (8/29) of cases of SCC. Twelve per cent (5/41) of cases of SCC were confirmed to have metastatic involvement of the local lymph nodes. Papillomata showing pre-malignant changes were identified in five cases. Seventy five per cent (36/48) of the animals presented were ponies. All were geldings, mean age 16.5 years. Penile amputation and urethrostomy, preputial ablation and proximal urethrostomy or local excision were used in the surgical management of these animals; three cases were inoperable and destroyed at presentation. Oedema, haemorrhage and stenosis of the urethrostomy site were encountered as post operative complications. Sixty six per cent (6/9) of animals with SCC of the glans penis (without urethral involvement), which had a known history over the follow up period, treated by penile amputation and urethrostomy survived for longer than 18 months. Similarly, of those with urethral involvement only 28.6 per cent (2/7) survived for a similar follow-up period. SCC not uncommonly affects the external genitalia of aged pony geldings and frequently the glans penis. If the lesion is identified before local metastasis occurs, penile amputation and urethrostomy is indicated and the prognosis is favourable.

Amputation, Surgical↗
PubMed1988

Possible homologies between photorefractoriness in sheep and birds: the effect of thyroidectomy on the length of the ewe's breeding season.

Comparisons are drawn between the photoperiodically driven breeding cycles in "long-day" birds and "short-day" mammals, emphasizing the importance of photorefractoriness as a key regulator in the timing processes. It is argued that the two types of breeding cycle may not be so radically different as previously thought and, indeed the cycles may be strictly homologous. Evidence in support of this comes from the role of the thyroid glands in seasonality. In starlings and quail, thyroidectomy prevents refractoriness developing and the birds remain in breeding indefinitely under long days. If the processes underlying refractoriness are similar across species then thyroidectomy should greatly alter the ewe's breeding cycle. In two experiments, Welsh Mountain ewes were thyroidectomized in the summer during anoestrus and their subsequent periods of oestrus monitored under various daylengths. There was no effect of thyroidectomy on the time when oestrous cyclicity began in the Autumn but the onset of anoestrus was profoundly disrupted. All the ewes continued to cycle well beyond the end of the normal breeding season and a number have continued throughout the entire period of anoestrus.

Animals↗
PubMed1987

Comparison of the Leicester Micropalliator and the Cardiff Palliator in the relief of postoperative pain.

Two devices for providing patient-controlled, on-demand analgesia were compared for 24 h after abdominal surgery. The Leicester Micropalliator delivered a mandatory background infusion of 1 mg h-1 in addition to on demand bolus doses of morphine 2 mg i.v. while the Cardiff Palliator provided only bolus doses of morphine 2 mg i.v. The Leicester Micropalliator provided analgesia superior or equivalent to that of the Cardiff Palliator in patients who had undergone hysterectomy or cholecystectomy, respectively, and there was no increase in side effects. The total doses of morphine administered over 24 h did not differ significantly between the two devices.

Adult↗
PubMed1987

Abnormalities in the immune system of children with beta-thalassaemia major.

We have studied both the humoral and cell mediated immune systems of 23 children with beta-thalassaemia major. In children who had not been splenectomized, a 3-fold expansion in the number of circulating B cells and a modest polyclonal gammopathy was present. Of these patients 70% had decreased numbers of circulating T4 cells; 83% were unresponsive to skin testing with Candida albicans, and the majority had decreased lymphocyte proliferative responses in vitro. In children who had been splenectomized, there was a 10-fold increase in the number of circulating B lymphocytes and a 2-fold increase in the number of T4 and T8 cells present in peripheral blood. Additionally, these patients as a group were more responsive to both skin testing and lymphocyte stimulation in vitro with Candida albicans. Seven patients had an inverted T4/T8 ratio. One child has positive serology to HIV by ELISA and Western Blot techniques with a normal T4/T8 ratio. Thus, while children with thalassaemia are at risk for exposure to HIV, the immunological abnormalities associated with the disease and/or its treatment necessitates cautious interpretation of any AIDS-related immunological changes.

Acquired Immunodeficiency Syndrome↗
PubMed1984

The intravenous intralipid tolerance test.

The half-life of an intravenously injected bolus of intralipid 20% was measured in normal rats in order to asess its relationship to reticuloendothelial system (RES) activity. Groups of animals were studied following various treatments, and the results compared to measurement of carbon clearance in similar groups. The RES effects of silica and C parvum were confirmed by the carbon clearance test, but no effect was seen on the half-life of intralipid. Intralipid clearance was shortened by fasting and the administration of intravenous heparin, neither of which affected carbon clearance. It is concluded that the intravenous intralipid test has no place in the asessment of RES function.

Animals↗
PubMed1984

Urolithiasis in the horse - a review of 13 cases.

The presenting signs, treatment and postoperative progress of 13 horses with vesical and urethral calculi are reviewed. Single, discrete stones were present in 10 animals in which the results of treatment were generally good. In three horses with sabulous cystic deposits, urolithiasis was associated with bladder paralysis and the response to treatment was poor.

Animals↗
PubMed1983

Histological changes following Nd YAG laser photocoagulation of canine gastric mucosa.

Tissue changes produced in the dog stomach by exposure to a Nd YAG laser varied from mild mucosal oedema to cell vaporisation. Intermediate degrees of damage caused a marked inflammatory response leading to extensive fibrosis in the submucosa and muscularis propria. The true extent of tissue damage was not apparent immediately, and treated mucosa that initially appeared intact sometimes sloughed several days later to leave an ulcer. The extent of damage and the rate of healing depended on the amount of laser energy used. With pulses at optimum laser power (75 w) and exposure time (0.4 sec), however, haemostasis was achieved in induced ulcers with total energy concentrations that did not produce full thickness tissue damage nor alter the healing rate from that observed in untreated ulcers. Thermal contraction was the primary haemostatic mechanism, thrombosis only occurring as a secondary effect.

Animals↗
PubMed1981

Cathepsin D: specificity of peptide-bond cleavage in type-I collagen and effects on type-III collagen and procollagen.

1. Cathepsin D, purified from bovine thymus, has a limited proteolytic effect on types I and III bovine collagens. The alpha 1 (I) chain was cleaved in native or denatured collagen only within the carboxy-terminal extra-helical sequence, the major site being between resides C6 (Leu) and C7 (Ser). The alpha 2 chain was unaffected in native collagen but was slowly cleaved between residues 782 (Phe) and 783 (Leu) in the denatured form. Cleavages, at 45 degrees C, in type III collagen occur within the extra-helical amino-terminal sequence, on the carboxy-terminal side of the lysine residue involved in intermolecular cross-linking. All three sites of action are within sequences of general hydrophobic character. 2. The very restricted cleavage of peptide bonds in denatured collagens can be ascribed to the infrequent occurrence of groupings of more than two hydrophobic residues and to the high content of the conformation-limiting residues proline and hydroxyproline. 3. The previously demonstrated failure of cathepsin D to solubilize a representative proportion of type III collagen from the fibres of bovine skin collagen [P.G. Scott and C.H. Pearson (1978) Biochem, Soc, Trans. 6, 1197-1199] may be explained by lack of ability of the enzyme to act on this collagen at 25 degrees C, in such a manner as to separate molecules joined by intermolecular cross-links involving the amino-terminal extrahelical region of the molecule.

Animals↗
PubMed1980

An outbreak of type C botulism in captive monkeys.

In an outbreak of type C botulism in a group of captive primates, six squirrel monkeys, six white throated capuchin monkeys and two weeper capuchin monkeys succumbed rapidly and died. Clostridium botulinum type C toxin was detected in the remains of the chopped chicken feed and in nine of 11 blood samples and one of three stomach contents samples from the affected animals.

Animals↗
PubMed1980

Ligation and sclerosis of the epididymis in the bull.

In an attempt to induce permanent aspermia the caudae epididymes of 17 bulls were subjected to ligation or injection with ethanolamine or chlorhexidine in dimethyl sulphoxide. Nylon and polyglycolic acid ligatures had little or no effect on the sperm counts although these materials were used in only three bulls. Steel ligation induced aspermia of several weeks' duration in four of six bulls. Although the effect in at least three of these animals might have been permanent, the trial was discontinued because the other two bulls, treated identically, showed little response. Ethanolamine injected into the epididymis also had little or no effect on the ejaculate. By contrast the chlorhexidine preparation produced an almost immediate aspermia sustained until the bulls were slaughtered a year later.

Animals↗
PubMed1980

NdYAG laser photocoagulation in the dog stomach.

Considerable discussion still centres around the relative merits of the Argon and Neodymium Yttrium Aluminum Garnet (NdYAG) lasers for the endoscopic treatment of gastrointestinal haemorrhage, although both are undoubtedly effect. We have carried out experiments to elucidate which factors determine the safety and efficacy of NdYAG laser photocoagulation. Histological studies on normal gastric mucosa showed that the depth of tissue damage depended mainly on the total incident laser energy, whereas the effectiveness of photocoagulation of induced gastric ulcers in heparinised animals depended on the laser power and the exposure time used. Optimum haemostasis with minimum tissue damage was obtained using pulses of 300 to 500 ms duration with energies of 25 to 40 J. We consider these parameters safe and effective for use in pilot clinical studies.

Animals↗