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Biomedical subjects

J A Parsons

Publications and source records attributed to J A Parsons.

At least 91 records · Page 5Linked to original sources
PubMed1979

Immunocytochemistry with osmium-fixed tissue. I. Light microscopic localization of growth hormone and prolactin with the unlabeled antibody-enzyme method.

Growth hormone and prolactin were localized on thin plastic sections of rat anterior pituitary gland and mammosomatotropic tumor MtTW15 that were fixed with osmium tetroxide (alone,mixed with aldehydes, or after aldehydes). Intense immunocytochemical staining for both antigens was obtained after plastic was removed from sections with an alcoholic solution of sodium hydroxide. The results indicated that antigenic determinants of rat prolactin and growth hormone were not completely destroyed or inactivated by fixation with osmium and embedment in epoxy resin, and that removal of the polymerized epoxy resin was necessary to obtain light microscopic postembedding immunocytochemical staining of these antigens. The results also demonstrated that tissues which have been conventionally processed for morphological evaluation by electron microscopy may be suitable for postembedding immunocytochemical staining of some antigens for light microscopy.

Animals↗
PubMed1979

Clinical application of pre-programmed insulin infusion: continuous subcutaneous insulin therapy with a portable infusion system.

Strict control of blood glucose was achieved by continuous subcutaneous insulin infusion with a specially adapted Mill Hill Infuser for 3-4 days. This led to normalisation of some of the intermediary metabolites. In a few patients, subcutaneous infusions have been carried out for periods up to 3 months with home monitoring of blood glucose, without infection or lipodystrophy. Short-term improvement of metabolic control was associated with recovery of abnormal renal glomerular permeability to albumin.

Alanine↗
PubMed1979

Technology of pre-programmable insulin delivery systems: continuous subcutaneous insulin infusion.

Dual-rate continuous subcutaneous insulin infusion was performed with a specially adapted Mill Hill Infuser. The infuser delivers 2 rates, a slow rate of ca. 50 microliter/h and an eightfold higher rate, designed to cover the increased requirement during meals. The high rate is engaged by pressing a button on the side of the pump, and returns automatically to the basal level after 17 min. Insulin is delivered to the subcutaneous side by a nylon cannula.

Blood Glucose↗
PubMed1978

Continuous subcutaneous insulin infusion: an approach to achieving normoglycaemia.

A study was performed to examine the feasibility of achieving long periods of near-normoglycaemia in patients with diabetes mellitus by giving a continuous subcutaneous infusion of insulin solution from a miniature, battery-driven, syringe pump. Twelve insulin-dependent diabetics had their insulin pumped through a subcutaneously implanted, fine nylon cannula; the basal infusion rate was electronically stepped up eightfold before meals. The blood glucose profile of these patients was closely monitored during the 24 hours of the subcutaneous infusion and compared with the profile on a control day, when the patients were managed with their usual subcutaneous insulin. Diet and exercise were standardised on both days. In five out of 14 studies the subcutaneous insulin infusion significantly lowered the mean blood glucose concentration without producing hypoglycaemic symptoms; in another six patients the mean blood glucose concentration was maintained. As assessed by the M value the level of control was statistically improved in six out of 14 studies by the infusion method and maintained in six other patients. To assess the effects of blood glucose control on diabetic microvascular disease it will be necessary to achieve long-term normoglycaemia in selected diabetics. The results of this preliminary study suggest that a continuous subcutaneous insulin infusion may be a means of maining physiological glucose concentrations in diabetics. Though several problems remain--for example, in determining the rate of infusion--longer-term studies with the miniature infusion pumps are now needed.

Adult↗
PubMed1978

Cancer of the nasopharynx in children.

The authors present 15 children with cancer of the nasopharynx. Of seven patients with primary epidermoid carcinomas, only two are alive and well. Only one of four patients with a primary soft tissue sarcoma is alive and well. Two of four patients with lymphoma of the nasopharynx are alive and well. All deaths were due to uncontrolled distant metastases. Only one patient (rhabdomyosarcoma) died with uncontrolled local disease. Radiotherapy to the primary and neck is recommended for all children with primary malignancy of the nasopharynx. Adjuvant chemotherapy may also be of value for all patients regardless of histopathology.

Adolescent↗
PubMed1978

Heterogeneity of the MtTW15 mammosomatotropic tumor. I. Light microscopic evaluation of cell types by means of immunocytochemistry, morphometric quantitation, fluorescence cytophotometry and radioimmunoassay.

Large MtTW15 pituitary tumors produced 200- to 800-fold elevations in serum growth hormone (GH) and prolactin (PRL) levels. Female tumor hosts showed doubling in body weight, milk secretion, and a 2-fold hepatosplenomegaly. Pituitaries of host animals were reduced by about 50% in both weight and concentrations of GH and PRL. Large tumors were well-encapsulated, multinodular and showed variable amounts of necrosis and hemorrhage. Cytofluorometric analysis revealed a range of 100-fold in nuclear DNA content of tumor parenchymal cells which were chromophobic, pleomorphic and frequently mitotic. Concentrations of hormones in tumors were less than in normal pituitaries and highly variable with the ratio of GH/PRL ranging up to 30-fold within the same tumor. Immunostaining and linear scanning quantitation showed that about 50% of the tumor cells contained immunodetectable hormones. Comparison of immunostained adjacent sections showed that hormone-containing tumor cells were pleomorphic, unequally distributed within nodules, lacking in distinctive identifying morphological characteristics and that they contained GH or PRL but not both hormones simultaneously. Collectively our results show that large MtTW15 tumors are comprised of a markedly heterogeneous population of tumor cells and they suggest that the hormone-containing cells are monohormonal secreting tumor cells which can produce GH or PRL but not both hormones.

Animals↗
PubMed1978

A sensitive bioassay of parathyroid hormone in plasma.

Understanding of calcium metabolism in health and disease has been retarded by the lack of an adequately sensitive bioassay of parathyroid hormone. The problem of dissociation of bioactivity and immunoactivity, well recognized for other polypeptide hormones, is exaggerated in the case of parathyroid hormone by the disproportionately long half-time in the circulation of the immunoreactive fragments. A new method of assaying the biological activity of parathyroid hormone in plasma has been developed, based on the cytochemical methods which have yielded highly sensitive bioassays of other polypeptide hormones. It depends on the stimulation of glucose 6-phosphate dehydrogenase activity in the distal convoluted tubules of segments of guinea-pig kidney maintained in vitro, and measured by microdensitometry. The limit of sensitivity of the assay is 5 fh/ml (bPTH); the index of precision is 0.09 +/- 0.04 (mean +/- SEM; n = 11).

Animals↗
PubMed1978

Insulin infusion into the portal and peripheral circulations of unanaesthetized dogs.

Changes in glucose, phosphate, potassium, non-esterified fatty acids (NEFA) and insulin in peripheral venous blood were compared in five unrestrained fasted dogs during different rates of insulin infusion by the portal and peripheral circulation. The 'low' rate of insulin infusion was that required to produce a fall in plasma glucose of 0.56-0.83 mmol/l (0.024 u/kg/h female, 0.012 u/kg/h male). Two-fold and four-fold higher rates are referred to as 'medium' and 'high' rates, respectively. In all dogs, dose-related reductions in the glucose concentration of peripheral blood resulted from increasing the rate of insulin by either route. At 'low' and 'high' rates of infusion the net response was independent of the route of administration, but the 'medium' rate of insulin infusion led to a greater degree of hypoglycaemia when given peripherally than intraportally. As expected, insulin infused peripherally resulted in graded increases in peripheral insulin levels as the rate of infusion was increased from low to high while, paradoxically, intraportal administration at low and medium infusion rates resulted in a mean decrease of peripheral insulin levels from control, the low-dose producing the most consistent fall. The fact that hypoglycaemia accompanied this fall during portal infusion suggests that these low doses of insulin had a direct effect on plasma phosphate resulting from the change in route of administration of insulin (i.e. increase during portal and decrease during peripheral infusion) also suggests a direct hepatic effect of insulin given intraportally.

Animals↗
PubMed1977

A miniature syringe pump for continuous administration of drugs and hormones: The Mill Hill infuser.

A miniature syringe pump has been developed for intravenous or subcutaneous infusion of the many drugs and hormones which produce better therapeutic responses when continuously delivered at a controlled rate than by repeated separate injections. The infuser uses disposable plastic syringes and is designed for precise tamper-proof delivery of 2 ml/24 h or 2 ml/8 h with quartz-crystal control, unaffected bt the dose-rate can be precisely determined by prescribing solutions of appropriate strength.

Hormones↗
PubMed1976

Anabolic effect of low doses of a fragment of human parathyroid hormone on the skeleton in postmenopausal osteoporosis.

Parathyroid hormone, injected daily in low dosage, exerted anabolic effects on the human skeleton, just as it does in the rat. Four postmenopausal women with primary osteoporosis were treated for six months with a synthetic fragment of human parathyroid hormone (hP.T.H. 1-34), given as a daily injection of 100 mug. This treatment caused a remarkable acceleration of bone turnover, indicated both by isotopic tracer and histological methods. At this normocalcaemic dose level, the increases in bone formation outweighed increases in resorption. Three of the four patients showed more positive calcium balances, and mean increases in calcium and phosphorus balances were statistically significant for the group as a whole, the changes being principally due to increased intestinal absorption of both elements. Many modifications of the present method of hormone administration are possible which could further increase the preponderance of anabolic effects. These results suggest that low doses of hP.T.H. 1-34, alone or in combination with other agents, may prove useful in the treatment of osteoporosis.

Absorption↗