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Biomedical subjects

D Morton

Publications and source records attributed to D Morton.

At least 73 records · Page 4Linked to original sources
PubMed1989

Step by step on a piece of string: an illustration of community work as a social health strategy.

This article describes the development of a community work approach to the problem of isolation within a semi-rural and urban community. Reasons for adopting a community work emphasis within this community health service are explained. Two projects which illustrate ways in which the approach was put into practice are described and implications and issues for health workers are discussed using community participation, empowerment, and co-ordination of services as a basis for discussion.

Community Participation↗
PubMed1988

Isolation and preliminary in vitro characterization of the porcine pulmonary intravascular macrophage.

Porcine intravascular macrophages were isolated by perfusion of the pulmonary vasculature with 0.1% collagenase solution. The isolated cells formed intercellular adhesion plaques with endothelial cells when incubated with porcine pulmonary artery, aorta, and corneal cups. Intercellular adhesion plaques were focal junctionlike membrane specializations consisting of paired submembranous amorphous densities subjacent to 15-20 nm gaps between parallel apposing cell membranes. The intermembranous space was filled with moderately electron dense, finely granular material. Adhesion plaques formed in 4-8 hours and resembled the adhesion plaques formed between pulmonary intravascular macrophages and endothelium in vivo. Alveolar macrophages and peripheral blood monocytes did not form intercellular adhesion plaques with endothelial cells. Intravascular macrophages had histologic and ultrastructural features of macrophages, were alpha naphthyl butyrate esterase positive, adhered to plastic coverslips after 1 hour of incubation, and were smaller than alveolar macrophages and endothelial cells. The formation of intercellular adhesion plaques in vivo and in vitro by cells with morphologic and histochemical features of macrophages distinguishes intravascular macrophages from monocytes and alveolar macrophages.

Animals↗
PubMed1988

Acute suppurative thyroiditis caused by Eikenella corrodens.

Eikenella corrodens is a slow-growing facultative anaerobe present in the normal oral flora. Two children have been described with acute suppurative thyroiditis with E corrodens as the major pathogen. Staphylococci are the most frequently identified pathogens in acute suppurative thyroiditis. Penicillin or ampicillin are the drugs of choice for infections caused by E corrodens. Anatomic defects should be searched for in children with acute suppurative thyroiditis.

Acute Disease↗
PubMed1988

The use of rabbits in male reproductive toxicology.

The rabbit is the smallest and least expensive laboratory animal in which serial semen samples can be obtained for morphologic, biochemical, and fertility evaluation. The female rabbit has a predictable reproductive cycle and can be artificially inseminated with a known amount of sperm during fertility testing. These advantages make the rabbit an extremely valuable model for studying the effects of chemicals or other stimuli on the male reproductive system. Quantitative evaluation of the testis, semen, and accessory reproductive organs is important in order to detect subtle effects of a chemical on reproductive capacity. Evaluation of testis size, serum hormone concentrations, and the number, morphology, motility, and fertility of sperm in the ejaculate can be performed serially in the live rabbit. Weights of testes and accessory reproductive organs, estimates of daily sperm production, and histomorphometric data on the seminiferous epithelium can be obtained after sacrifice. Multinucleated spermatids, focal tubular hypospermatogenesis, swelling of spermatocytes, and cytoplasmic vacuoles in Sertoli's cells occur commonly in testes of control rabbits. These changes may be confused with toxic lesions. The incidence of multinucleated spermatids may be increased by stress associated with handling or the environment. Histomorphometric evaluation may be required to prove that a test compound has an adverse effect on the male reproductive system.

Animals↗
PubMed1986

The indirect binding of triose-phosphate isomerase to myofibrils to form a glycolytic enzyme mini-complex.

Binding of triose-phosphate isomerase (D-glyceraldehyde-3-phosphate ketol-isomerase, EC 5.3.1.1) to muscle myofibrils depends upon the concurrent binding of either fructose-bisphosphate aldolase (EC 4.1.2.13), glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12) or both of these enzymes together. Thus triose-phosphate isomerase does not bind directly to myofibrils but to glycolytic enzymes already bound to the myofibril. This was established using 125I-labelled enzymes, which are required to provide the necessary sensitivity for the measurement of the complex multiphasic adsorption isotherms. In the presence of aldolase, the most stable stoichiometric relationship is two aldolase bound per triose-phosphate isomerase. The results show that not all sites of aldolase or glyceraldehyde-3-phosphate dehydrogenase binding are available for triose-phosphate isomerase binding. Nevertheless, the results suggest the formation under particular circumstances of a minicomplex spanning the catalysis of fructose 1,6-bisphosphate to 3-phosphoglycerate. Such a complex could provide the physical basis of metabolic channeling in which metabolic intermediates are not released from the complex.

Animals↗
PubMed1986

Spermatid giant cells, tubular hypospermatogenesis, spermatogonial swelling, cytoplasmic vacuoles, and tubular dilatation in the testes of normal rabbits.

Testes of 36 normal New Zealand white rabbits (8, 15, 18, 26, and greater than 52 weeks of age) were examined by light and electron microscopy. The incidence and number of affected tubules were determined for spermatid giant cells, focal tubular hypospermatogenesis, cytoplasmic swelling of spermatogonia, intracytoplasmic vacuoles in seminiferous epithelium, and tubular dilatation. Spermatogenesis commenced at 15-18 weeks of age and was present in all rabbits by 18 weeks. Spermatid giant cells occurred in 96% of rabbits 15 weeks of age and older. Focal hypospermatogenesis was present in 14-57% of testes once active spermatogenesis began. Ninety-seven percent of testes in all age groups combined had spermatogonial swelling. Infrequent dilated seminiferous tubules were present in five rabbits. Ultrastructurally, spermatid giant cells were round cells with multiple nuclei that appeared to arise by widening of narrow intercellular bridges that normally connect spermatogenic epithelial cells. Pale-staining spermatogonia consisted of cytoplasmic and nuclear swelling with disruption of plasma and nuclear membranes. Tubules with spermatogonial swelling were more numerous in 15- and 18-week-old rabbits. There were no significant differences in incidence or extent of spermatid giant cells, focal hypospermatogenesis, cytoplasmic vacuoles, or tubular dilatation between age groups after spermatogenesis commenced. Although the cause of these changes is not known, they were frequent findings in normal rabbits 15 weeks of age and older.

Animals↗
PubMed1985

Live Oka/Merck varicella vaccine in healthy children. Further clinical and laboratory assessment.

A clinical trial among 137 healthy children, ages 1 to 12 years, was conducted with four different doses (4,350, 870, 435, and 43 plaque-forming units [pfu]) of live Oka/Merck varicella vaccine to evaluate clinical reactions and selected laboratory parameters and to determine the minimum effective dose and induction time of antibody. The vaccine was well tolerated with no significant difference in the rate of reported symptoms by dose. The frequency of varicellalike rash was 3% (4/137); all rashes were mild. Serum aminotransferase values were essentially unchanged after vaccination. Minor variations found in platelet counts after vaccination were not associated with any bleeding, bruising, or clotting. Among initially seronegative children who received doses of 435 pfu or greater, 94% assayed at two weeks and 100% assayed at four or six weeks seroconverted. The geometric mean titers were similar for all four doses at six weeks. IgG and IgA responses were demonstrated with no relation to the vaccine dose.

Alanine Transaminase↗
PubMed1985

Malignant histiocytosis in four dogs.

The clinical and pathologic features of 4 dogs with malignant histiocytosis were evaluated. The most common clinical signs were weight loss, lethargy, lymphadenopathy, hepatosplenomegaly, and anemia. Neoplastic histiocytic infiltrates most commonly were found in the spleen, bone marrow, liver, or lymph nodes. Malignant histiocytosis was considered as a differential diagnosis for anemic dogs with lymphadenopathy and/or hepatosplenomegaly.

Animals↗
PubMed1984

Metabolism of leukotriene A4 by human erythrocytes. A novel cellular source of leukotriene B4.

Human erythrocytes transformed leukotriene A4 into leukotriene B4. Metabolism was proportional to the erythrocyte concentration, even at subphysiological levels (0.08-4 X 10(9) erythrocytes/ml). Comparative metabolic studies excluded the possibility that leukotriene B4 originated from trace amounts of polymorphonuclear leukocytes or platelets present in the purified erythrocyte suspensions. For example, suspensions of isolated platelets (100-500 X 10(6) cells/ml) failed to convert leukotriene A4 into leukotriene B4; and conversion by suspensions of isolated polymorphonuclear neutrophils was insufficient to account for the amounts of leukotriene B4 formed by erythrocytes. Leukotriene B4 formation was maximal within 2 min and substrate concentration dependent. Enzymatic activity originated from a 56 degrees C labile nondialyzable (Mr greater than 30,000) soluble component in the 100,000 X g supernatant obtained from lysed erythrocytes. In contrast to the contemporary view, our results indicate that human erythrocytes are not metabolically inert in terms of eicosanoid biosynthesis. The role of human erythrocytes during inflammatory or pulmonary disorders deserves re-examination in this context.

Arachidonic Acids↗
PubMed1982

Iron balance in the common vampire bat Desmodus rotundus.

1. Total body iron in the common vampire bat was 80 +/- 67 mg Fe/kg body wt (mean +/- SD). 2. Mean (+/- SD) iron absorption as measured by the double isotope method was 0.068 +/- 0.0032% Fe. A typical adult bat ingests 6.1 mg Fe/day (Morton & Wimsatt, 1980) of which approximately 4.2 microgram Fe is absorbed. 3. Body iron turnover (BIT) was estimated from the decrease in specific radioactivity of the blood over more than a year. The mean (+/- SD) of the half-life of iron turnover was 379 +/- 101 days and that of the estimate of BIT. 0.14 +/- 0.04% TBI/day. This is equivalent to a loss of approximately 4.6 microgram Fe/day. 4. The common vampire bat maintains iron balance by severely limiting the percentage of iron absorbed from its very high iron diet.

Absorption↗
PubMed1981

S100 protein: a marker for human malignant melanomas?

S100 protein is a nervous-system-specific cytoplasmic protein which is also present in human malignant melanoma cell lines. To test for its tumour specificity, biopsy specimens from normal tissue and a wide variety of tumours were tested for S100 by complement fixation and immunofluorescence tests. S100 was present in all of thirteen samples of malignant melanoma tissue and absent from nineteen samples of non-melanocytic tumours, and from normal skin and normal lymph nodes. S100 levels did not correlate with tyrosinase activity in the tissues examined. Detection and measurement of S100 protein may help distinguish poorly differentiated amelanotic malignant melanoma from tumours of obscure histological origin; they may also aid the detection of micrometastatic disease in the lymph nodes and other tissues of melanoma patients.

Complement Fixation Tests↗