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Biomedical subjects

J M Hamilton

Publications and source records attributed to J M Hamilton.

At least 91 records · Page 5Linked to original sources
PubMed1983

Oestrogen-induced renal carcinogenesis in the hamster: ultrastructural and hormonal studies of the pars intermedia before and after withdrawal of oestrogen.

Long-term oestrogen treatment of male hamster induced renal carcinoma and pituitary enlargement due to hypertrophic and hyperplastic change in the pars intermedia. The latter effect was accompanied by ultrastructural abnormalities in pars intermedia cells and elevation of serum MSH concentration. Oestrogen treatment was stopped after 36 weeks and animals were killed at intervals from 8 to 36 weeks after oestrogen withdrawal. Nearly complete tumour regression occurred during the 36 weeks following cessation of oestrogen and by 28...36 weeks the pars intermedia cells regained normal ultrastructural appearance. However, pituitary enlargement and elevated serum MSH levels persisted throughout the post oestrogen recovery period.

Animals↗
PubMed1980

Inverted nipples.

A method of correction of inverted nipples is presented, which appears to be simple, safe, and effective, leaving little scarring.

Breast↗
PubMed1979

Ultrastructure of intermediate lobe of the pituitary and melanocyte-stimulating hormone secretion in oestrogen-induced kidney tumours in male hamsters.

One group of male Syrian hamsters was killed after various periods of diethylstilboestrol (DES) treatment, ranging from 6 to 36 weeks. All developed renal tumours by 24 weeks. DES also induced hyperplastic and neoplastic changes in the pars intermedia of the pituitary with proliferation of MSH-secreting cells and elevated serum MSH concentration. Another group of male Syrian hamsters was given DES for 36 weeks followed by cessation of hormone treatment. The animals were killed at various intervals from 12 to 36 weeks after DES withdrawal. In these animals the DES-induced renal tumours underwent regression whilst the pituitary changes persisted until the termination of the experiment. The findings suggested that the hormone MSH may be implicated in renal carcinogenesis but plays no role in the maintenance of the established tumours.

Animals↗
PubMed1978

Studies of estrogen induced renal tumours in male Syrian hamsters. I. Cytochemical studies of lysosomal enzymes acid phosphatase and beta-glucuronidase.

The localization and concentration of lysosomal enzymes acid phosphatase and beta-glucuronidase in kidney cells of Syrian hamsters after DES administration were studied. A positive cytoplasmic reaction was demonstrated for both enzymes. Increased activity of these enzymes were observed in renal tumour in contrast to normal homologous cells. These results can be explained on the basis that lysosomal enzymes were synthesized in tumour cells at a higher rate or it may be due to the invasion of tumour tissue by hydrolase rich microphages.

Acid Phosphatase↗
PubMed1978

Effect of oestrogen on the pituitary gland of male Syrian hamsters. I. Electron microscope studies of pars intermedia.

The ultrastructure of the pars intermedia of normal and oestrogen-treated male Syrian hamsters is described. 3 types of cell were observed in normal gland, namely, 2 types of "light" cell and a "dark" cell. Light cells were regular in shape with round or oval nuclei and could be divided into type 1 and 2 by the size of their granules 200 to 250 nm in type 1 and 100 to 150 nm in type 2. Dark cells were fewer in number, irregular in outline with highly-indented chromatin-rich nuclei and occasional secretory granules in the Golgi area. Treatment for 6 weeks with diethylstibestrol (DES) 0.6 mg in 0.2 ml distilled water subcutaneously 3 times per week failed to induce recognisable change in the pars intermedia although after 12 weeks treatment cytoplasmic changes were observed. From that time until the experiment ended after 30 weeks of treatment progressive changes indicative of enhanced synthesis of hormone were present, greater cytoplasmic volume, hypertrophy of the Golgi apparatus, marked development of endoplasmic reticulum and ribosomes, increased numbers of secretory granules and the presence of granules within granules.

Animals↗
PubMed1977

Oestrogen receptors in canine mammary tumours.

One hundred and twenty-nine canine mammary tumours of varying histological types were examined for the presence of oestrogen binding protein by the dextran-coated charcoal method with the binding parameters of the reaction determined by Scatchard plots. By this method, 39 per cent of the 129 mammary tumours were shown to contain oestrogen receptor protein. This figure fell to 25 per cent for benign tumours and rose to 52 per cent for malignant tumours. There was no correlation between the histological nature of tumours and oestrogen receptor content in either benign or malignant forms. Oestrogen receptors were not demonstrable in normal mammary tissues. Whether the presence of oestrogen receptors in a tumour is indicative of hormonal dependence as is reported for human breast tumours is being investigated in the bitch.

Animals↗
PubMed1977

Homologous radioimmunoassay for canine prolactin.

A homologous double antibody radioimmunoassay has been developed for canine prolactin. Purified canine prolactin was iodinated by lactoperoxidase/H2O2 to an average of 101 "+/- 10.1 muCi/microgram. Antiserum was used at a final dilution of 1:80 000 and at this concentration bound approximately 20% of the added tracer in the absence of competing unlabelled prolactin. Partial cross-reaction was observed with ovine and bovine prolactin but there was no cross-reaction with a highly purified canine growth hormone preparation. Dilutions of pregnant and lactating bitch sera were parallel to the purified canine prolactin standard curve. Mean prolactin levels in normal male and anoestrous females were 8.8 +/- 0.8 and 12.6 +/- 2.6 ng/ml, respectively. Thyrotrophin-releasing hormone (TRH) induced a consistent elevation in prolactin levels 15--30 min after intravenous injection.

Animals↗
PubMed1977

The place of electrical stimulation in the physiotherapy of leprosy.

The production of nerve and muscle impulses by faradic and interrupted direct current, and the "Strength-duration curves" plotted for normal, denervated, and partially denervated muscles, are described. The advantages and disadvantages of such electrical stimulation in the testing of recent paralysis, the treatment of recent paralysis, and following tendon transfer surgery, in leprosy patients, are discussed. In the light of these, electrical stimulation is concluded to have only a minor role in the Physiotherapy of leprosy.

Adolescent↗
PubMed1976

Oestrogen receptors in feline mammary carcinomas.

Twenty primary or metastatic felline mammary tumours were assayed for the presence of oestrogen receptors by the dextran-coated charcoal method. In only two of the tumours was the presence of specific oestrogen binding protein demonstrable. The high negative rate in comparison with human and canine mammary tumours assayed under similar conditions seemed to be a peculiar feature of the feline tumours and suggested a lack of oestrogen dependency. The possibility remains that other hormones may be concerned with the growth of feline mammary tumours and further work is in progress.

Adenocarcinoma↗
PubMed1976

Purification of canine prolactin by preparative isotachophoresis.

Preparative isotachophoresis in polyacrylamide gel using carrier ampholytes as 'spacers' has been used to purify prolactin from canine pituitary extracts. Using Ampholine pH 5-8 as spacers, a prolactin fraction was obtained which was essentially homogeneous as judged by the criteria of disc electrophoresis and isoelectric focusing. Amino acid analysis indicated a close similarity between canine and ovine prolactin. A growth hormone fraction, identified by its electrophoretic mobility, was also obtained although this was heterogeneous in disc electrophoresis at alkaline pH.

Amino Acids↗