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Biomedical subjects

J Cohen

Publications and source records attributed to J Cohen.

At least 1,405 records · Page 78Linked to original sources
PubMed1980

An outpatient approach to female sterilization with methylcyanoacrylate.

MCA is a tissue adhesive which can be delivered transcervically to the Fallopian tubes by means of the FEMCEPT device. In the patients treated with this system, both prior to hysterectomy and on an ambulatory basis, there have been no significant complications or side effects. In the most recent series of ambulatory patients treated with the REMCEPT-MCA system, the bilateral tubal closure rate was 78%.

Ambulatory Care↗
PubMed1980

The Psychiatric Status Schedule for epidemiological research. Methodological considerations.

The Psychiatric Status Schedule (PSS) was designed to improve the research value of clinical judgments in the assessment of psychopathology. Although constructed with data from psychiatric patients, it is also intended for use in case finding, as in epidemiological studies of the general population. Its usefulness for this purpose has been questioned on the basis of the low internal consistency of many of the PSS scales in a general population sample and strata thereof. We challenged this methodological stance. Using the same data set, the PSS can be shown to have validity for epidemiological use, in that it discriminates outpatients from the general population and identifies psychiatric "cases" variously defined.

Diagnosis, Computer-Assisted↗
PubMed1980

Characterization of separated cell types from developing rat cerebellum. Transport of [3H]GABA by preparations enriched in Purkinje cells and astrocytes.

The characteristics of [3H]GABA transport were investigated in preparations greatly enriched in different classes of cerebellar cells. In contrast to observations in situ, isolated Purkinje cells readily accumulated [3H]GABA. In comparison with astrocytes, the Vmax of the high-affinity uptake process was sixfold higher (0.31 vs. 0.05 nmol/min/10(6) cells) and the apparent Kt twofold greater (2 vs. 1 microM). In contrast to these cell types, uptake was very low in granule cell-enriched preparations. cis-1,3-aminocyclohexane carboxylic acid was a potent inhibitor of [3H]GABA uptake by the Purkinje cells and a weak blocker in astrocytes, while the converse was the case for beta-alanine. Diaminobutyric acid strongly inhibited uptake in both cell types. [3H]GABA transport was Na+ dependent in both cell classes. However, veratridine and ouabain selectively blocked [3H]GABA accumulation in the Purkinje cells, which were also more sensitive than the astrocytes to the glycolysis inhibitor, NaF. The results indicated, therefore, marked differences between Purkinje cells and astrocytes in the properties of both the [3H]GABA transport systems and the underlying metabolic processes.

Animals↗
PubMed1980

Specific neuronal localization by immunofluorescence of 10 nm filament polypeptides.

Rabbit antisera have been produced to bovine brain 10 nm filament preparations and to purified polypeptide constituents of brain 10 nm filaments. Antisera to the former preparation stain both neurons and astrocytes, whereas antisera to two polypeptides of mol. wt 155 000 and 210 000 are neuron specific. It is therefore concluded that these latter polypeptides are components of neurofilaments and the mixed staining pattern obtained with the antisera to the whole brain 10 nm filament preparation is due to the presence in this material of a mixture of neurofilaments and glial filaments which are thus biochemically distinct forms of 10 nm filament.

Animals↗
PubMed1980

Control of membrane fusion in exocytosis. Physiological studies on a Paramecium mutant blocked in the final step of the trichocyst extrusion process.

Previous studies on exocytosis in Paramecium using mutants affecting trichocyst extrusion permitted us to analyze the assembly and function of three intramembrane particle arrays ("ring" and "rosette" in the plasma membrane, "annulus" in the trichocyst membrane) involved in the interaction between these two membranes. Using a conditional mutation, nd9, which blocks rosette assembly and prevents exocytosis at the nonpermissive temperature, we have analyzed the effect of temperature on the secretory capacity of nd9 cells. By combining several techniques (physiological studies, microinjections, inhibition of fatty acid synthesis, and freeze-fracture analysis) we demonstrate (a) that the product of the mutated allele nd9 is not thermolabile but that its activity is dependent upon temperature-induced changes in the membrane lipid composition and (b) that the product of the nd9 locus is a diffusible cytoplasmic component whose interaction with both plasma membrane and trichocyst membrane is required for rosette assembly and exocytosis. The data provide physiological evidence for the existence of a molecular complex(es) linking the two membranes and involved in the control of membrane fusion; we discuss the possible nature and function of these links.

Animals↗
PubMed1980

Genetic analysis of the relationships between the cell surface and the nuclei in Paramecium tetraurella.

In Paramecium tetraurelia, a number of mutations have been shown to affect simultaneously cortical organization (attachment of trichocysts to the cortex) and nuclear divisions (Ruiz et al. 1976). In order to analyze the genetic and physiological basis of this correlation, and we have isolated new mutations affecting the properties of the trichocysts and studied their genetic relationships with other previously known mutations. Of 24 to 28 loci controlling the biogenesis and properties of the trichocysts, mutations only in the 16 to 20 loci tht control trichocysts attachment to the cortex result in nuclear defects. Cytological observations show that all these mutants display the same set of nucler abnormalities: in particular, rounded shape of the resting macronucleus mispositioning and defective elongation of the dividing macronucleus and unequal repartition of the marco- and micronuclei. This common syndrome is independent of both the mutagenic origin and the mutated locus. Furthermore, by microinjection, it is possible to localize the site of action of the mutations in either the trichocyst compartment or the nontrichocyst compartment. It was found by this technique that the nuclear syndrome is also independent of the site of action of the mutation. All the genetic and physiological data support the conclusion that the nuclear defects are the consequence of the lack of trichocyst attachement to the cortex: in wild-type cells, trichocyst attachment would induce a membranar or perimembranar state necessary for correct nuclear positioning during cell division. In the absence of trichocyst attachment, the cortical control of nuclear division would be abolished. The possible involvement of cytoskeletal links between surface and nuclei is discussed.

Animals↗
PubMed1980

A selected review of retinal research and study.

Papers from the American Journal of Ophthalmology, Archives of Ophthalmology, and British Journal of Ophthalmology from July 1977 to June 1978 were selected on the basis of potential value to clinical optometrists. The 54 papers pertaining to various aspects of retinal pathology are presented under these headings--damage from fiber optics light, preretinal membranes, acute posterior multifocal placoid pigment epitheliopathy, toxoplasmosis, histoplasmosis, diabetes, retinal pigment epithelium, retinitis pigmentosa, retinoblastoma, retrolental fibroplasia and retinal dysplasia, other retinopathies, and retinal tears and detachments.

Adolescent↗
PubMed1980

The mechanism of alpha-adrenergic inhibition of catecholamine release.

1 The effect of alpha-adrenoceptor agonists on membrane adenosine triphosphatase (ATPase) activity was studied in membranes from the bovine adrenal medulla and the rat submaxillary gland. 2 alpha-Adrenoceptor agonists (10(-7) to 10(-5) M) enhanced significantly Na,K-ATPase activity but not Mg-ATPase activity in adrenal medulla. This effect was not observed in membranes from phaeochromyocytoma. Phenylephrine (10(-5) M), naphazoline (10(-5) M) and clonidine (10(-5) M) caused a significant increase of the activity of Na,K-ATPase (but not of Mg-ATPase) in the submaxillary gland. The enhancement became more prominent after ligature of the submaxillary duct but disappeared completely after superior cervical ganglionectomy. Thus, the effect of the alpha-adrenoceptor agonists was due to an action on adrenergic nerve terminals in the submaxillary gland. 3 Phenylephrine and naphazoline did not affect 45Ca uptake but enhanced the rate of 45Ca efflux from adrenal medullary slices in vitro. 4 Phenylephrine enhanced the rate of 45Ca efflux from slices of submaxillary gland (with previous ligation of the duct); this was blocked by phentolamine and sympathetic denervation. Therefore phenylephrine was acting on the adrenergic nerve terminals. 5 It is suggested that the inhibition by alpha-adrenoceptor agonists of the exocytotic release of catecholamines from adrenergic nerve terminals and from chromaffin cells may be due to activation of the sodium pump, which results in enhancement of calcium efflux, causing a reduction of free intracellular Ca2+.

Adrenal Gland Neoplasms↗
PubMed1980

Arrhythmias in patients with hypereosinophilia: a comparison of patients with and without Löffler's endomyocardial disease.

About one third of patients with Löffler's endomyocardial disease have abnormal electrocardiograms and some develop arrhythmias and die suddenly. To assess the significance of these findings, continuous ambulatory ECG monitoring was performed for 48 hr on 6 patients with acute or chronic forms of Löffler's endomyocardial disease, and the types and frequencies of arrhythmias were compared with recordings from 6 other patients with equally high blood eosinophil counts who did not have clinically evident cardiac disease. It was hoped that this would show whether arrhythmias were related to high blood eosinophil counts, cardiac injury or other factors. Three of the patients with endomyocardial disease had multiple ventricular extrasystoles with episodes of ventricular arrhythmias and occasional supraventricular arrhythmias which had not been detected with conventional ECGs. These abnormalities did not occur in 2 of the patients with acute endomyocardial lesions who died, nor were they found in patients who did not have congestive cardiac failure or in the control patients. Rhythm disturbances appeared to be most closely related to the development of cardiac failure and they resolved after successful cardiac surgery. Multiple ventricular extrasystoles and arrhythmias occurring in these patients with Löffler's endomyocardial disease are probably due to metabolic changes in the heart associated with cardiac failure and mechanical changes related to valvular dysfunction rather than a direct effect of the eosinophils themselves on the heart.

Adult↗
PubMed1980

Microtubules and control of macronuclear 'amitosis' in Paramecium.

The 'amitotic' division of the macronucleus during binary fission in P. tetraurelia includes a detailed sequence of shape changes that are temporally coordinated with the adoption of a series of well-defined positions and orientations inside the cell. The deployment of nucleoplasmic microtubules that is spatially correlated with the shaping ritual is more complex and precise than has been reported previously. Macronuclear division is not amitotic. It is not a simple constriction into two halves. As a dividing macronucleus starts to elongate it becomes dorsoventrally flattened against the dorsal cortex of the organism and assumes an elliptical shape. Concurrently, an elliptical marginal band of intranuclear microtubules assembles that has the same spatial relationship to nuclear shape as the marginal microtubules assembles that has the same spatial relationship to nuclear shape as the marginal microtubule bands of certain elliptical vertebrate blood cells have to cell shape. The band breaks down as further elongation occurs and the nucleus adopts the shape of a straight and slender sausage. Most of the intranuclear microtubules assemble as elongation starts and break down shortly after elongation is completed; the majority are oriented parallel to the longitudinal axis of the nucleus throughout elongation. Some of them are attached to nucleoli and are coated with granules which are almost certainly derived from the cortices of nucleoli. The peripheral concentration, interconnexion, orientation, and overlapping arrangement of microtubules, and the reduction in microtubule number per nuclear cross-section as elongation proceeds at a rate of about 40 micrometers min-1, are all compatible with the provision of a microtubule sliding mechanism as the main skeletal basis for elongation. There are indications that this mechanism is augmented by anchorage and/or active propulsion of nucleoli that may perhaps facilitate fairly equitable segregation of chromosomal material to daughter nuclei.

Animals↗
PubMed1980

Abnormal microtubule deployment during defective macronuclear division in a Paramecium mutant.

The tam 8 mutant of Paramecium tetraurelia is a representative of a class of mutants characterized by abnormal nuclear divisions during binary fission and the failure of trichocysts to attach to the plasma membrane. Compared with wild-type organisms the following abnormalities occur in tam 8 individuals. (I) The spherical interphase macronucleus is not positioned near the oral apparatus; it is randomly located in the cytoplasm of interfission organisms. (2) The macronucleus does not migrate towards the anterior dorsal cortex as its division starts, nor is it dorsally and subcortically positioned as it elongates. (3) Elongating macronuclei exhibit variable and irregular shapes. (4) This elongation is delayed and reduced. (5) Longitudinally oriented microtubules assemble in the nucleoplasm of dividing macronuclei but their spatial deployment is abnormal. (6) Unequal segregation of micronuclei between daughter organisms occurs during binary fission. The abnormal arrangement of nucleoplasmic microtubules provides support for the proposal that a microtubule sliding mechanism is involved during the elongation of dividing macronuclei. The extent to which macronuclear division may be controlled by the cell cortex is considered in relation to tthe pleiotropic effects of the tam 8 mutation.

Animals↗