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Biomedical subjects

M Prince

Publications and source records attributed to M Prince.

83 records · Page 5Linked to original sources
PubMed1984

Detection of gastrointestinal bleeding by radionuclide scintigraphy.

Scanning with Technetium 99m labeled autologous red blood cells was performed in 59 patients with clinical suspicion of acute and/or intermittent, chronic gastrointestinal bleeding. In 36 patients (61%), a definite site of bleeding could be demonstrated. A strong correlation with other modalities such as upper and lower gastrointestinal endoscopy, contrast angiography, and surgical exploration was found. Overall sensitivity of the procedure was 91%; specificity 100% and accuracy 93.3%. It is suggested that radionuclide scintigraphy provides a completely noninvasive, simple, and sensitive procedure which may be routinely used for the detection and localization of gastrointestinal bleeding.

Adult↗
PubMed1982

Phosphate depletion therapy in two ectopic calcification syndromes.

Ectopic calcification may be a complication of a wide variety of pathologic conditions. Subcutaneous calcification frequently results in restriction of motion at joints in addition to cosmetic deformity. Parenchymal tissue calcification may result in decreased organ function. Dietary phosphate restriction and total body phosphate depletion with aluminum containing antacids were used in an attempt to decrease the deposition of subcutaneous calcium phosphate which occurs with two separate syndromes. Two subjects with hyperphosphatemic tumoral calcinosis were studied by metabolic balance, by long-term clinical evaluation, and routine laboratory and radiographic techniques before and after 1 year of phosphate depletion. One patient with a newly described syndrome--normocalcemic, hypercalciuric, subcutaneous calcification--was similarly studied. The etiology of this disorder is unknown. No consistent clinically significant evidence of regression of the lesions was noted in either syndrome, although one patient with tumoral calcinosis did demonstrate some regression of his lesions. It is not clear if this response failure was due to the intrinsic nature of the diseases or to failure of patient compliance secondary to a relatively unpalatable diet.

Adolescent↗
PubMed1982

Comparative in vitro evaluation of the nitinol inferior vena cava filter.

An inferior vena cava filter made from nitinol, a thermal shape memory alloy, was evaluated. A series of in vitro experiments was designed to assess its shape recovery, orientation, and positioning after delivery and its embolus-capturing efficiency. For comparison, the Mobin-Uddin and Kimray-Greenfield filters were also tested. The results indicate that the nitinol filter is easily and accurately delivered and is superior to the other filters in its ability to capture emboli. In addition, it showed no tendency to migrate or to elevate the upstream hydrostatic pressures significantly.

Alloys↗
PubMed1981

Insulin binding, internalization, and receptor regulation in cultured human fibroblasts.

Insulin binding to receptors was studied using monolayers of cultured normal human fibroblasts. Binding was rapid and inversely related to the incubation temperature; prolonged periods of steady-state binding were achieved at all temperatures studied and the amount of degradation of extracellular insulin was minimal. Competition curves demonstrated half-maximal inhibition of 125I-insulin binding at an unlabeled insulin concentration of 125I-insulin binding at an unlabeled insulin concentration of 7 ng/ml. Scatchard plots of the binding data were curvilinear and revealed that fibroblasts contained about 7,000 receptor sites per cell. Bound 125I-insulin dissociated from fibroblasts with a t 1/2 of 10 min at 30 degrees C and 35 min at 16 degrees C. After 60 min dissociation at 30 degrees C, 45% of the dissociated radioactivity consisted of 125I-insulin degradation products, whereas only 8% of the dissociated material was in the form of degraded products after 60 min of dissociation at 16 degrees C. This indicates that fibroblasts possess a temperature-sensitive receptor-mediated process for insulin degradation. Preincubation of the monolayers with insulin led to a hormone-induced loss of insulin receptors. Thus, incubating cells with 25 ng/ml insulin for 6 h at 37 degrees C caused a 50% reduction in subsequently measured 125I-insulin binding. This hormone-induced receptor loss was sensitive to physiologic insulin levels, with approximately 5 ng/ml causing a half-maximal receptor loss. When monolayers were treated with the lysosomotropic agent chloroquine and subsequently incubated with 5 X 10(-11) M 125I-insulin, a 130% increase in cell-associated radioactivity was observed after 120 min at 30 degrees C. In summary, 1) cultured normal human fibroblasts possess insulin receptors that exhibit kinetic properties and specificity identical to that of other insulin target cells; 2) incubation of fibroblasts with physiologic concentrations of insulin causes a marked loss of cell-surface insulin receptors; and 3) receptor-bound 125I-insulin is internalized through an energy-dependent endocytotic pathway and subsequently degraded by a chloroquine-sensitive reaction.

Cells, Cultured↗
PubMed1980

Regulation of insulin receptors: evidence for involvement of an endocytotic internalization pathway.

Cultured human fibroblasts degrade insulin by a receptor-mediated process. When intracellular hormone degradation is inhibited by chloroquine, 125I-labeled insulin internalizes and accumulates intracellularly. In contrast, cultured IM-9 lymphocytes do not degrade receptor-bound insulin or accumulate 125I-labeled insulin in the presence of chloroquine. Insulin-induced receptor loss occurs in both cell types, and chloroquine inhibits this process in fibroblasts but not in IM-9 lymphocytes. Transglutaminase is a membrane-associated enzyme thought to mediate the process of ligand-induced receptor aggregation and internalization; levels of this enzyme were high in fibroblasts but barely detectable in IM-9 lymphocytes. Furthermore, dansylcadaverine--a potent inhibitor of transglutaminase--blocked insulin-induced receptor loss in fibroblasts but was without effect in IM-9 lymphocytes. These results support the concept that insulin receptor regulation is mediated via an endocytotic internalization pathway in human fibroblasts and that the mechanisms of this process differ among cell types.

Cadaverine↗
PubMedDate not supplied

Urethritis due to Neisseria meningitidis in a London genitourinary medicine clinic population.

A retrospective study was performed in a department of genitourinary medicine to determine the prevalence and clinical features of urethral and cervical infection with Neisseria meningitidis among patients being screened for sexually transmitted diseases. During the 28 month period of the study 11 isolates (from 10 patients) of N. meningitidis were identified from 5571 urethral cultures from homosexual men (0.2%). This compares with an isolation rate of 4.7% for N. gonorrhoeae; 1.2% samples screened for chlamydial antigen were positive. There were no isolates from 8992 urethral cultures from heterosexual men or 15,976 cervical cultures. Eight of the cases identified had features of urethritis at diagnosis; 6 were diagnosed initially as non-specific urethritis (NSU) and 2 as gonorrhoea on the basis of microscopy of a urethral smear. Eight of the 10 patients were treated with amoxycillin and/or a tetracycline, and all but one had a clinical and microbiological cure. In the study population the prevalence of N. meningitidis infection was low and restricted to homosexual men; however, it may be associated with symptoms.

Adult↗