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Biomedical subjects

T Russell

Publications and source records attributed to T Russell.

At least 55 records · Page 3Linked to original sources
PubMed1986

Metastasizing meningioma.

A very unusual case of metastatic spread of a meningioma is described. The clinical presentation was of extradural spinal cord compression, without evidence of a primary tumor. Computed tomography did not reveal any intracranial meningioma; the histopathology of the extradural spinal tumor was identical with that of two intracranial meningiomas previously excised.

Adult↗
PubMed1985

Effect of mannitol on cerebral blood flow and cerebral perfusion pressure in human head injury.

Patients with severe head injury frequently have evidence of elevated intracranial pressure (ICP) and ischemic neuronal damage at autopsy. Mannitol has been used clinically to reduce ICP with varying success, and it is possible that it is more effective in some types of head injury than in others. The aim of the present study was to determine the effect of mannitol on ICP, cerebral perfusion pressure (CPP), and cerebral blood flow (CBF) in patients with severe head injury, and to discover if these effects differed in different types of injury. Measurements of CPP, ICP, and CBF were made in 55 patients with severe head injury. In general, the resting level of CBF was higher in patients with diffuse injury (mean 50.2 ml/100 gm/min) than in those with focal injury (mean 39.8 ml/100 gm/min). Mannitol consistently reduced ICP and increased CPP and CBF by 10 to 20 minutes after infusion. The lowest flows (31.8 ml/100 gm/min) were recorded from the most damaged hemispheres of patients with focal injuries and elevated ICP. The baseline levels of flow did not correlate with ICP, CPP, Glasgow Coma Scale score, or outcome. Only four of the 55 patients had a CBF of less than 20 ml/100 gm/min in either or both hemispheres. The few low CBF's in this and other studies may reflect the steady-state conditions under which measurements are made in intensive care units, and that these patients have entered a phase of reperfusion.

Adult↗
PubMed1984

Cerebrospinal fluid rhinorrhea 34 years after trauma: a case report and review of the literature.

Posttraumatic cerebrospinal fluid (CSF) rhinorrhea has been recognized since the 17th century, and its association with intracranial infection has been well documented. However, CSF rhinorrhea usually presents during the 1st month after trauma. Cases presenting more than 3 months after trauma are unusual. The authors report a case of CSF rhinorrhea that presented 34 years after head injury.

Adult↗
PubMed1982

Insulin and multiplication stimulating activity (an insulin-like growth factor) stimulate islet (beta-cell replication in neonatal rat pancreatic monolayer cultures.

A possible role for insulin in stimulating islet beta-cell replication was examined in neonatal rat pancreatic monolayer cultures. Addition of insulin to serum-free medium increased the mitotic index and stimulated dose-dependent increases in [3H]-thymidine incorporation in nuclei of islet beta-cells in aldehyde-thionine-stained autoradiographs. The effects of insulin were not associated with any significant changes in glucagon or somatostatin levels in the culture media. Multiplication stimulating activity (MSA), an insulin-like growth factor, was about 100-fold more potent than insulin: 3 ng/ml MSA stimulated a half-maximal increase in thymidine labeling of beta-cell (+63%, P less than 0.005), whereas 300 ng/ml insulin was required for a similar effect. The maximal effects of insulin and MSA were similar, and the combination of maximal stimulatory concentrations of MSA (30 ng/ml) and insulin (3000 ng/ml) was not more effective than either substance added alone, suggesting that both peptides act on the same mechanism(s) regulating beta-cell replication. Furthermore, an antibody to the insulin receptor did not prevent the stimulatory effects of either insulin or MSA on thymidine labeling of beta-cells. These results demonstrate that insulin can stimulate islet beta-cell replication directly, possibly through a receptor for MSA or another insulin-like growth factor.

Animals↗
PubMed1982

Preparation of rat islet B-cell-enriched fractions by light-scatter flow cytometry.

Flow cytometry has been examined as a method to separate islet cells into homogeneous subpopulations. Collagenase-isolated rat islets were dissociated into single cells and these were analyzed and sorted according to their low forward angle light scattering properties by using automated flow cytometry. Light scatter histograms showed two peaks of viable cells. Radioimmunoassay of hormone content in cell fractions collected across the the two peaks showed that glucagon-containing cells were concentrated towards the left side of the left peak and somatostatin-containing cells were concentrated towards the right side of the left peak, whereas insulin-containing cells were clearly enriched in the right peak. The B-cell-enriched fraction (90% B cells, 3% A cells, 2% D cells) exhibited significant insulin secretory responses to glucose (16.7 mM), and 3-isobutyl-1-methylxanthine (0.1 mM), during a 24-h culture period, and these responses were slightly greater than those observed in the original mixed islet cell preparation (66% B cells, 14% A cells, and 4% D cells). These results indicate that flow cytometry can be applied to sort pancreatic islet cells into populations enriched in specific endocrine cell types for further study of the functions of individual cell types.

Animals↗
PubMed1979

Factors from fibroblasts promote pancreatic islet B cell survival in tissue culture.

A possible role for fibroblasts in promoting the survival and function of islet B cells in tissue culture was examined by the addition of fibroblasts from a mouse embryo cell line (3T3-L2) to islet cell monolayer cultures prepared from newborn rat pancreases. Co-culture of islet cells with fibroblasts significantly increased the recovery of insulin in medium and cells after 7 days of culture in medium supplemented with 10% serum, and prevented the deterioration of islet cells cultured in serum-free medium. Similarly- serum-free medium, conditioned by cultures of either 3T3-L2 fibroblasts or fibroblasts freshly isolated from newborn rat pancreases, maintained the release and content of insulin in islet cell monolayer cultures at levels four- to eightfold higher than in control serum-free medium. Serum-free, fibroblast-conditioned medium also enhanced the survival of intact islets maintained in free-floating culture for 28 days. The active factor(s) in fibroblast-conditioned medium has a high molecular weight and is heat-stable. We conclude that fibroblastic cells produce a macromolecular factor(s) capable of enhancing the survival of functional islet B cells in tissue culture.

Animals↗
PubMed1979

Xanthogranulomatous pyelonephritis (XGP): a local disease with systemic manifestations. Report of 23 patients and review of the literature.

The clinical, pathological and radiographic findings of 135 cases of xanthogranulomatous pyelonephritis have been reviewed. It is a form of renal suppuration and obstruction most commonly seen in middle aged women although all ages and both sexes may be affected. There is no race predilection. Gram-negative organisms are usually present and bilateral involvement has not been reported. The most common offending organism is Proteus mirabilis. Hepatic dysfunction is seen and appears to normalize with removal of the XGP process. Preoperative angiography may increase the accuracy of differentiating this disorder from hypernephroma and may aid the surgeon in planning his approach to kidney resection depending upon the staging of XGP. Chronic renal failure is not usually a feature of XGP and nephrectomy is curative without any incidence of recurrence.

Female↗
PubMed1975

Influence on adipocyte plasma membrane bound protein kinase by feedback regulator.

Protein kinase, phosphodiesterase and adenylate cyclase of plasma membrane of adipocytes and the effect of the feedback regulator (FR) on these three enzymes was measured and compared. The basal level ratio of adenylate cyclase to phosphodiesterase to protein kinase was 1:1.9:3.0. Epinephrine and/or FR alters this ratio. FR stimulated protein kinase activity up to 3 fold in the presence of a wide range of enzyme concentrations, 5-50 mug membrane protein/tube. The concentration of FR effective for stimulation of membrane protein kinase was much greater than that needed for inhibition of adenylate cyclase and phosphodiesterases. The inhibition by FR on adenylate cyclase was the most potent effect among the 3 enzymes. 1 U (or 2 U/ml) of FR inhibited 50% of the adenylate cyclase activity in a defined system. The maximum effective concentration of FR for stimulation of membrane protein kinase was greater than 10 U/ml. Histone type 11A was the best substrate for protein phosphorylation so far observed. The FR stimulatory effect was observed at all substrate concentrations used ranging from 1-5 mg/ml. A NaF concentration curve shows that 15 mM NaF gave maximum phosphorylation. The stimulatory effect of FR was observed both in the presence and absence of NaF. Protein kinase of adipocyte plasma membrane was mainly cAMP-independent. The effect of FR (20 U/ml) in stimulation of protein phosphorylation was much greater than that of cAMP (1 X 10(-6) M). The cAMP and FR effects seemed to be additive. Preincubation of plasma membrane with FR in the absence of ATP resulted in no decrease but slight increase in protein kinase activity. A shift in protein kinase, phosphodiesterase and adenylate cyclase ratios by FR suggests the regulatory role of FR in cAMP metabolism in adipocytes.

3',5'-Cyclic-AMP Phosphodiesterases↗