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Biomedical subjects

J Winter

Publications and source records attributed to J Winter.

At least 289 records · Page 16Linked to original sources
PubMed1980

Studies on cultured rat Schwann cells. III. Assays for peripheral myelin proteins.

Rabbit antisera to the rat myelin proteins P0 and P1 were used to assay for the presence of these components by both immunochemical and immunofluorescence methods. The antiserum to P0 did not react detectably with polyacrylamide gels containing central myelin, or with P1 and P2 in peripheral myelin; it did react with P0 in peripheral myelin, and in extracts of adult and neonatal sciatic nerve. When reacted with frozen tissue sections using indirect immunofluorescence, it did not stain central myelin but did stain myelin in adult sciatic nerve, the myelinated fibres in cervical sympathetic trunk and occasional areas in neonatal sciatic nerve where Schwann cells had presumably begun to form myelin. Antiserum to basic protein reacted with both of the basic protein bands in central and peripheral myelin, but not P0; P1 and P2 were detectable in adult and neonatal sciatic nerve. In indirect immunofluorescence assays, the antiserum stained both central and peripheral myelin, the few myelinated fibres of sympathetic trunk and myelinating regions of neonatal sciatic nerve. Cultured secondary rat Schwann cells showed no detectable reaction with either reagent, using either technique. We conclude that these three proteins are probably expressed as a consequence of the neuron-Schwann cell interaction that initiates myelination.

Animals↗
PubMed1980

Myelin-specific proteins and glycolipids in rat Schwann cells and oligodendrocytes in culture.

We have used antibodies to identify Schwann cells and oligodendrocytes and to study the expression of myelin-specific glycolipids and proteins in these cells isolated from perinatal rats. Our findings suggest that only Schwann cells which have been induced to myelinate make detectable amounts of galactocerebroside (GC), sulfatide, myelin basic protein (BP), or the major peripheral myelin glycoprotein (P0). When rat Schwann cells were cultured, they stopped making detectable amounts of these myelin molecules, even when the cells were associated with neurites in short-term explant cultures of dorsal root ganglion. In contrast, oligodendrocytes in dissociated cell cultures of neonatal optic nerve, corpus callosum, or cerebellum continued to make GC, sulfatide and BP for many weeks, even in the absence of neurons. These findings suggest that while rat Schwann cells require a continuing signal from appropriate axons to make detectable amounts of myelin-specific glycolipids and proteins, oligodendrocytes do not. Schwann cells and oligodendrocytes also displayed very different morphologies in vitro which appeared to reflect their known differences in myelinating properties in vivo. Since these characteristic morphologies are maintained when Schwann cells and oligodendrocytes were grown together in mixed cultures and in the absence of neurons, we concluded that they are intrinsic properties of these two different myelin-forming cells.

Aging↗
PubMed1980

Isolation and characterization of fecal bacteria capable of 16 alpha-dehydroxylating corticoids.

For more than a decade it has been known that the fecal flora of humans and rats includes organisms capable of 16 alpha-dehydroxylating corticoids, but their identity has remained unknown. To isolate these organisms, Mueller-Hinton agar plates were seeded with fresh feces from Proteus-free rats and incubated anaerobically. On an average, 1 of every 35 colonies consisted of organisms synthesizing 16 alpha-dehydroxylase. Isolation of the individual colonies yielded two obligate anerobes, strains 144 and 146, which elaborated the enzyme. The steroid transformation could be attained by the microbial culture alone in prereduced media or in aerobic media in the presence of Escherichia coli. Although both strains were phenotypically similar to Eubacterium lentum, they differed between themselves in their enzymatic equipment.

Adrenal Cortex Hormones↗
PubMed1980

Edge enhancement of computed tomograms by digital unsharp masking.

Edge enhanced images can be produced on existing commercial computed tomographic equipment by a method called "digital unsharp masking" without any expense or computer software development. This technique permits display of anatomic areas having an extremely wide range of densities, while making edge detail more apparent.

Humans↗
PubMed1980

Edge enhancement computed tomography scanning in inflammatory lesions of the middle ear.

The high resolution modification of an EMI 5005 scanner was utilized with an edge enhancement technique to study inflammatory lesions of the temporal bone. Bone erosions caused by cholesteatomas can be accurately delineated because of the circumscribed nature of expansion. The soft tissue masses cannot be appreciated by present CT techniques. Erosions of the horizontal semicircular canal and involvement of the sinus tympani are readily visualized by CT scanning. Computed tomography is limited in demonstrating the stapes superstructure and horizontal portion of the facial canal due to the inability to obtain good coronal scans. The remaining ossicles can be demonstrated with equal clarity with pluridirectional tomography.

Bone Resorption↗
PubMed1980

Combined gas cisternography and edge-enhanced computed tomography of the internal auditory canal.

Gas cisternography was combined with edge-enhanced computed tomography (CT) in 6 patients and demonstrated the seventh and eighth cranial nerves thorugh both the cerebellopontine angle cistern and the internal auditory canal in the normal patients. The normal nerve outline was lost when a tumor was contained within the canal. This technique is a more reliable means of identifying small tumors than relying on non-filling of the canal by positive contrast media or gas.

Humans↗
PubMed1980

Varied appearance of trigeminal neuroma on CT.

The computed tomographic (CT) scans of five patients with surgically and histologically proven trigeminal neuromas demonstrated the varied appearance of this tumor. In this series, tumors appeared in the middle cranial fossa, the posterior cranial fossa, or extended into both. Prior to contrast infusion, the tumors showed low density, normal brain density, or mixed normal and low density on the CT Scan. After contrast infusion, all tumors were well circumscribed with marked enhancement, which was either homogeneous or inhomogeneous. None of the trigeminal neuromas had surrounding brain edema. The three larger tumors had significant mass effect with hydrocephalus and displacement of the fourth ventricle or compression of adjacent cisterns.

Adult↗
PubMed1980

Bacterial intracranial aneurysms.

The treatment of 13 patients with bacterial intracranial aneurysms is reported. The incidence of bacterial intracranial aneurysms was 4% of all patients admitted with intracranial aneurysms and 3% of all patients admitted with bacterial endocarditis. Each patient had neurological signs or symptoms suggestive of intracranial disease prior to the diagnosis of an aneurysm. Alpha Streptococcus was the most common infecting organism. All patients were treated with specific, high-dose antibiotics, and five patients underwent surgery as well. There were no surgical deaths. Six of eight nonsurgically treated patients died. A review of the literature confirms a high mortality for patients treated with only antibiotics, and a low mortality for elective surgery. The authors conclude that 1) patients with bacterial endocarditis, who develop sudden severe headache, focal neurological signs or symptoms, or seizures, should undergo serial cerebral angiography every 7 to 10 days throughout their hospitalization; 2) if an aneurysm is identified it should be excised whenever possible; and 3) patients with proximal or multiple aneurysms should be considered for surgery.

Adult↗
PubMed1980

Poisoning of animals in the Los Angeles area with pesticides during 1977.

During 1977, there were 289 pesticide exposure incidents involving animals that were handled by the Thomas J. Fleming Memorial Poison Information Center in Los Angeles. Almost all of this service was provided to veterinarians and most of the incidents involved dogs. Cases handled by this center are considered typical for small animal practices in urban areas of California. Ingestion was the major route of exposure. As recently as 10 years ago, arsenic, strychnine, and phosphorus were major causes of such poisonings. During 1977, the n-methylcarbamates (27%), anticoagulants (19%), and organo-phosphates (15%) were the major pesticides involved in exposure incidents. Lesser percentages of cases attributed to a specific chemical included: Vacor (5%), metaldehyde (4%), chlorinated hydrocarbons (4%), and arsenicals (4%). A variety of other pesticides, classified as miscellaneous, were also involved in poisonings to a lesser extent.

Animals↗
PubMed1979

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↗
PubMed1979

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↗
PubMed1979

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↗
PubMed1979

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↗
PubMed1979

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↗