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Biomedical subjects

J Winter

Publications and source records attributed to J Winter.

At least 19 recordsLinked to original sources

Regional differences in the distribution of capsaicin-sensitive target-identified adult rat dorsal root ganglion neurons.

A retrograde labelling technique combined with a cobalt uptake assay in cultured adult rat dorsal root ganglion (DRG) neurons were applied to study the distribution of capsaicin sensitivity in relation to different peripheral targets. This study shows that there are regional differences between skin, skeletal muscle and urinary bladder; 20-30% of skin afferents, 40% of muscle afferents and 60% of bladder afferents were found to be capsaicin-senditive. This may reflect differences in the proportion of chemosensitive afferents innervating different peripheral tissues.

Animals

Cell-type-specific markers for distinguishing and studying neurons and the major classes of glial cells in culture.

We have used 4 cell-type-specific markers to identify individual glial and neuronal cells in dissociated cell cultures of neonatal rat sciatic nerve, dorsal root ganglia (DRG), optic nerve, cerebellum, corpus callosum, cerebral cortex and leptomeninges. Schwann cells were identified with antibodies against rat neural antigen-1 (Ran-1), neurons with tetanus toxin, astrocytes with antibody against the glial fibrillary acidic protein (GFAP) and oligodendrocytes with antibody against galactocerebroside. All of these ligands react with cell surface molecules except for anti-GFAP antibody which binds to intracellular glial filaments. Using two-fluorochrome immunofluorescence we have studied the distribution of various glycoproteins and glycolipids on these 4 major neural cell types in short-term cultures. We have found that (1) although Ran-1 is expressed on glial and neuronal tumours, it was not found on normal astrocytes, oligodendrocytes or neurons; (2) Thy-1 was present on fibroblasts and some neurons but not on the majority of leptomeningeal cells or on oligodendrocytes or astrocytes in short-term cultures (however, it was expressed on some astrocytes in longer term cultures); (3) the 'large external transformation sensitive' (LETS) protein could be detected on fibroblasts and leptomeningeal cells but not on neurons or glial cells; (4) GM1 was present on all neurons, most oligodendrocytes and approx. 50% of other cell types; sulfatide and GM3 were only detectable on oligodendrocytes, while globoside was only found on some neurons. In addition, we were able to identify putative microglial cells by the presence of cell surface receptors for IgG and by their phagocytic activity; they did not express and of the cell-type-specific defining markers.

Animals

Characterization of a C21 neutral steroid hormone transforming enzyme, 21-dehydroxylase, in crude cell extracts of Eubacterium lentum.

A strain of the obligate anaerobe, Eubacterium lentum, isolated from human feces, catalyzes the 21-dehydroxylation of 11-deoxycorticosterone to progesterone. A quantitative radiochromatographic assay was developed to measure 21-dehydroxylase activity in cell extracts. Maximum enzyme activity in cell extracts required both a reduced pyridine nucleotide and an oxidized flavin coenzyme. However, photochemically reduced flavin (FMNH2) could replace the requirement for NAD(P)H plus oxidized flavin. NAD(P)H : flavin (either FMN or FAD) oxidoreductase activity was detected spectrophotometrically in cell extracts assayed under anaerobic conditions. 21-Dehydroxylase was active from pH 5.4 to 8.5 with an apparent optimum between 6.4 and 6.8 using mixtures of NADH plus FMN as coenzymes. The substrate concentration at half-maximal reaction velocity was 8.0 microM and a specific acitivity of 5.8 nmol [3H]progesterone formed . h-1 . mg-1 protein was determined using [3th]deoxycorticosterone as substrate. Atabrine, rotenone, acriflavin, and 2,4-dinitrophenol (all at 1 mM) inhibited 21-dehydroxylase activity in cell extracts by 25, 24, 35 and 84%, respectively. These results suggest that 21-dehydrogenase may be coupled to a NAD(P)H : flavin oxidoreductase system in E. lentum.

Autoradiography

Bacterial metabolism of corticoids with particular reference to the 21-dehydroxylation.

Clostridium paraputrificum, an obligate anaerobe recovered from human feces, reduces the alpha,beta-unsaturated carbonyl of deoxycorticosterone, corticosterone, cortisone, and cortisol. The same steroids are 21-dehydroxylated by Culture 116, recently isolated from human feces, and by a closely related organism, Eubacterium lentum. The 21-dehydroxylase has no effect on hydroxyl groups at carbon atoms 11 and 17.

Adrenal Cortex Hormones

Complete degradation of carbohydrate to carbon dioxide and methane by syntrophic cultures of Acetobacterium woodii and Methanosarcina barkeri.

Methanosarcina barkeri (strain MS) grew and converted acetate to CO2 and methane after an adaption period of 20 days. Growth and metabolism were rapid with gas production being comparable to that of cells grown on H2 and CO2. After an intermediary growth cycle under a H2 and CO2 atmosphere acetate-adapted cells were capable of growth on acetate with formation of methane and CO2. When acetate-adapted Methanosarcina barkeri was co-cultured with Acetobacterium woodii on fructose or glucose as substrate, a complete conversion of the carbohydrate to gases (CO2 and CH4) was observed.

Acetates

Failure of naloxone to alter growth hormone and prolactin levels in acromegalic and in hyperprolactinaemic patients.

We examined the effects of high-dose intravenous naloxone administration in four acromegalic patients (mean serum growth hormone level 72 ng/ml) and in seven hyperprolactinaemic women (mean serum prolactin level 59 ng/ml), in order to assess whether this opiate antagonist would be effective in lowering growth hormone and prolactin levels. No effect was observed. This lack of effect suggests that an opioid pathway is not involved in the maintenance of elevated growth hormone or prolactin secretion in these patients. However, conclusions regarding the possible role of endogenous opioids in regulation of pituitary function in normal individuals cannot be drawn from this study.

Acromegaly

New markers for Eubacterium lentum.

Of 37 strains of Eubacterium lentum and phenotypically similar organisms, 26 (70%) synthesized a corticoid 21-dehydroxylase and/or a 3 alpha-hydroxysteroid dehydrogenase. It appeared that the corticoid 3 alpha-hydroxysteroid dehydrogenase was identical to the bile acid 3 alpha-hydroxysteroid dehydrogenase. Steroid-metabolizing enzymes were found both in E. lentum and in phenotypically similar organisms. E. lentum is characterized by nitrate reduction and enhanced growth in the presence of arginine. Many phenotypically similar organisms possess either one or the other of the two markers. In contrast, using the steroid-metabolizing enzymes as markers, a "steroid-active" and a "steroid-inactive" group were established with minimal overlapping of metabolic characteristics. Synthesis of the steroid enzymes was positively correlated with production of gas from H2O2 and formation of H2S. A simple method for the detection of corticoid 21-dehydroxylase and 3 alpha-hydroxysteroid dehydrogenase, one or both of which were present in 92% of the steroid-active group, is described.

3-Hydroxysteroid Dehydrogenases

Osteogenic sarcoma after retinoblastoma radiotherapy.

Development of osteogenic sarcoma after retinoblastoma radiotherapy in three patients, two of whom were siblings, is reported. Pluridirectional tomography and plain skull radiography demonstrated soft tissue masses, sinus opacification, and bone destruction and sclerosis in all three patients. Computed tomography reliably indicated the presence or absence of intracranial tumor extension in the two patients in whom it was performed. Radionuclide bone scanning was a useful adjunct for osteosarcomatous detection.

Eye Neoplasms

The accuracy of predicting histologic grades of supratentorial astrocytomas on the basis of computerized tomography and cerebral angiography.

This report concerns a group of 49 patients who had been diagnosed as having gliomas on the basis of CT scans plus angiograms and for whom histologic proof was available. Ninety percent were found to be gliomas, 4% were metastases, and histology was unclear in the rest. Combining the CT criteria of inhomogeneous enhancement and surrounding edema with one or more of three angiographic signs (early venous drainage, stain, abnormal vessels) allowed a more confident diagnosis of glioblastoma.

Astrocytoma

Extensions of paranasal sinus tumors and inflammatory disease as evaluated by CT and pluridirectional tomography.

CT and pluridirectinal tomography are compared in their ability to show the extent of paranasal sinus tumors or benign aggressive processes. Thirty-one cases are reviewed; CT was superior to pluridirectional tomography in showing spreads of tumor to all clinically important areas, including the infratemporal fossa, nasopharynx, orbit, and intracranial compartment. CT not only consistently allowed less equivocal interpretation, but also enabled us to qualify orbital involvement as intra- or extraconal, and to quantitate better both brain and infratemporal fossa involvement. We feel that CT scanning is the better way to determine the extent of such pathology.

Adult

Metabolism of biliary steroids by human fecal flora.

Biliary excreted steroid hormones are metabolized by the intestinal flora. The metabolic pathways of deoxycorticosterone and progesterone, including the bacterial species involved, have been established. The pathways for other biliary steroids are unknown. Information on the biological activities of the metabolites is lacking, but methods for their investigation are now available. Evidence suggests that the formation of the metabolites is influenced by dietary habits, and that, in some cases, it may be controlled by suppression of the responsible bacteria.

Bacteria

Steroids and apparent cerebral atrophy on computed tomography scans.

Computed tomography scans of 15 long-term steroid users showed varying degrees of apparent cerebral atrophy, not expected at their ages (8 to 40 years). Most were suffering from autoimmune diseases. There appeared to be some correlation between dosage and degree of apparent atrophy. There was surprisingly little clinical evidence of cerebral dysfunction associated with this apparent atrophy. In two of the cases, the appearance of the brain improved following decrease or cessation of steroid use. Speculations are made on possible causes.

Adolescent