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Biomedical subjects

E Cohen

Publications and source records attributed to E Cohen.

At least 199 records · Page 11Linked to original sources
PubMed1991

Corneal ulcer and adverse reaction rates in premarket contact lens studies.

We analyzed clinical data on 22,739 contact lens wearers who were studied and whose lenses were approved under 48 manufacturer-sponsored studies for the Food and Drug Administration between 1980 and 1988. The incidence of corneal ulcers was low in the cosmetic (nontherapeutic) daily-wear soft and rigid gas-permeable lens wearers (1/1,923 and 1/1,471 patient-years, respectively). Corneal ulcers and severe adverse reactions occurred two to four times more frequently in extended-wear cosmetic soft and rigid gas-permeable lens wearers than in cosmetic daily-wear lens wearers. Aphakic extended-wear soft lens users were nine times more likely to develop a corneal ulcer when compared to the soft daily-wear cosmetic group. Corneal abrasions and keratitis accounted for 81 of 159 severe adverse reactions, whereas corneal ulcers accounted for 28 of 159 adverse reactions. The data indicate that overnight extended wear of contact lenses is associated with a greater risk of serious, sight-threatening complications than daily wear.

Aphakia↗
PubMed1991

Postgastrostomy tube deformity on upper GI series.

Three cases are presented in which a focal concave deformity occurred along the greater curvature of the stomach on upper gastrointestinal (GI) series. These patients all had recent removal of a surgically placed gastrostomy tube from a similar location. This deformity appears to be related, at least in part, to invaginated gastric mucosa intentionally produced during surgical gastrostomy tube placement. This association and appearance should be noted as it may mimic other lesions.

Adult↗
PubMed1991

Peri-cholecystic hyper-echogenicities in necrotizing enterocolitis: a specific sonographic sign?

The authors report a new sonographic pattern found in association with neonatal necrotizing enterocolitis in 5 newborns: hyperechogenicities around the gallbladder. The pattern probably corresponds to extension of the disease to the perivesicular space. The most probable hypothesis for that extension is diffusion by contiguity through the lesser sac and/or the right gutter. The hyperechogenicities could be related to the foamy infiltrate typical of NEC. Air within the pericholecystic vascular system similar to portal air could be another (less probable) explanation.

Enterocolitis, Pseudomembranous↗
PubMed1991

Photoprotection of Bacillus thuringiensis kurstaki from ultraviolet irradiation.

Irradiation of Bacillus thuringiensis var. kurstaki HD1 at 300-350 nm for up to 12 hr using a photochemical reactor results in a rapid loss of its toxicity to larvae of Heliothis armigera. Photoprotection of the toxic component was obtained by adsorption of cationic chromophores such as acriflavin (AF), methyl green, and rhodamine B to B. thuringiensis. AF gave the best photoprotection and a level of 0.42 mmol/g dye absorbed per gram of B. thuringiensis was highly toxic even after 12 hr of ultraviolet (uv) irradiation as compared to the control (77.5 and 5% of insect mortality, respectively). Ultraviolet and Fourier-transform infrared spectroscopic studies indicate molecular interactions between B. thuringiensis and AF. The nature of these interactions and energy or charge transfer as possible mechanisms of photoprotection are discussed. It is speculated that tryptophan residues are essential for the toxic effect of B. thuringiensis. It is suggested that photoprotection is attained as energy is transferred from the excited tryptophan moieties to the chromophore molecules.

Bacillus thuringiensis↗
PubMed1991

HEADSS, a psychosocial risk assessment instrument: implications for designing effective intervention programs for runaway youth.

In this article, we present data obtained with the psychosocial interview instrument, HEADSS (Home, Education, Activities, Drug use and abuse, Sexual behavior, Suicidality and depression) that was administered to High Risk Youth Clinic clients at their initial visits during a 1-year period. Of the 1,015 new patients, 63% were homeless/runaway youths and 37% were living with their families. Utilizing the HEADSS interview instrument, we compared homeless/runaway youths to nonhomeless youths in a number of areas, including risks for human immunodeficiency virus (HIV) infection. Our results showed that homeless teens tended to be younger, female, and white compared to their nonhomeless counterparts. They were more likely to have dropped out of school and were far more likely to be depressed and actively suicidal. They demonstrated all forms of drug abuse. They engaged in first sexual intercourse at an earlier age, and experienced a higher incidence of sexual abuse and prostitution. They were 6 times more likely to be at risk for HIV infection.

Adolescent↗
PubMed1991

Microcircuitry related to the receptive field center of the on-beta ganglion cell.

1. We have investigated the anatomic basis for the Gaussian-like receptive field center of the on-beta ("X") ganglion cell in the area centralis of cat retina. Three adjacent on-beta cells were reconstructed from electron micrographs of 279 serial sections cut vertically through a patch of retina at approximately 1 degree eccentricity. 2. All the bipolar synapses on these cells were identified, and about one-half of these were traced to type b1 bipolar cells, which formed a regular array in the plane of the retina. 3. On average, seven b1 cells contributed to a beta cell: bipolar axons near the middle of the beta dendritic field tended to give many contacts (12-33 contacts); axons near the edge of the field tended to give few contacts (3-4 contacts). 4. Each b1 cell collected from four to seven cones, and the mean number of cones converging through the b1 array to a beta cell was 30. 5. Assuming equal effectiveness for all b1----beta cell synapses, a spatial weighting function was derived from these results. The mean radius of this function at 1/e amplitude for three beta cells was 18.0 +/- 1.1 (SD) microns. This is considerably narrower than the corresponding measurements of the beta cell receptive field center (28 +/- 3 microns) at this eccentricity. 6. It is concluded, in agreement with previous work, that all cones encompassed by the beta cell's dendritic field and those slightly beyond it connect directly to the beta cell via the b1 bipolar cell array. However, the center of the beta cell receptive field is still broader by approximately 60%. This suggests that pooling of cone signals may occur at the level of the outer plexiform layer.

Animals↗
PubMed1991

Seborrheic skin and acne vulgaris as protective factors against the development of basal cell epithelioma.

This study was conducted in order to evaluate a possible protective role of seborrheic complexion and a history of acne on the development of basal cell epithelioma (BCE). For this purpose, 77 patients with this tumor were examined and asked to fill out a questionnaire. The questionnaire included demographic data and questions about skin type, eye and hair colors, sun exposure habits and a past history of acne. The nature, number and location of tumors, the texture of skin and acne scars were noted by a physician. A group of 93 age-, sex- and skin-color-matched patients served as controls. The results show a clear relationship between seborrheic features and a lower risk of developing BCE, after controlling for solar exposure using the Mantel-Haenszel summary measure. The same trend was found in patients with a history of acne. Whether ultraviolet light absorption by sebum, an anticancer activity of Propionibacterium acnes or other factors play a protective role against the development of BCE is as yet unclear.

Acne Vulgaris↗
PubMed1991

Effect of cyclosporine A on the hearing loss in Behçet's disease.

Thirty-five patients with Behçet's disease (20 under cyclosporine A [CyA] treatment and 15 under the conventional therapy), 12 patients suffering from endogenous uveitis, and 35 normal subjects were evaluated audiologically before entering the study and were followed up for at least a year. Twenty-eight Behçet patients (80%) showed some degree of hearing loss. The averaged pure tone audiogram of the Behçet group showed statistically significant auditory deficits in comparison with that of the control group. None of either the Behçet group or the uveitis group showed any hearing deterioration during the follow-up period. Five Behçet patients under CyA therapy demonstrated improvement in their hearing. The difference between the two groups of Behçet patients (CyA versus conventional treatment) was found to be statistically significant (p less than .05). Thus, CyA might serve as an important mode of treatment of sensorineural hearing loss on an inflammatory "autoimmune" background.

Acoustic Impedance Tests↗
PubMed1991

The effect of in vitro irradiation on human NK cell activity. A preliminary report.

Natural killer activity of peripheral blood cells was evaluated after in vitro irradiation at doses ranging between 100 and 1600 cGy. Natural killer (NK) cells from normal donors exhibited a trend towards increased cytotoxicity peaking at about 600 cGy and then gradually decreasing. NK cells isolated from peripheral blood of cancer patients showed a lower baseline of activity, which was less affected by the same doses of in vitro irradiation. A distinction could be made between patients with early disease and those with advanced cancers; patients with early cancers showing NK activity close to that of normal donors.

Acute Disease↗
PubMed1990

Demonstration of cell types among cone bipolar neurons of cat retina.

We identified all the cone bipolar cells (80) in a small patch of one retina and then studied in detail the complete subset (42) that sends axons to sublamina b of the inner plexiform layer. The point was to learn whether the 'types' suggested previously, based on a few examples from a large population, could be substantiated or whether there would be intermediate forms. Tissue from the area centralis (1 degree eccentricity), was prepared as a series of 279 ultrathin sections and photographed in the electron microscope. Thirteen cells were reconstructed completely and parcelled into five categories (b1-b5) based on external morphology. For nine of these cells (two from categories b1-b4 and one from b5) most of the synaptic inputs and outputs were identified. When these nine cells were parcelled according to their synaptic patterns, they sorted into the same five categories. The remaining 29 cells in the population, though not reconstructed, were studied in detail by tracing their processes through the series. Ten of these cells, those near the margin of the series, were incomplete. The other 19 cells had essentially the same distribution of morphologies and synaptic patterns as the subset studied by total reconstruction: when plotted in multiparametric space, they formed distinct clusters corresponding to the five morphological categories. There was no hint of intermediate forms. That all the neurons in the population sort into some cluster (no intermediate forms), and that each neuron sorts into the same cluster by different criteria, argues that the clusters represent natural types. Each type forms a regular array in the region studied with an axonal 'coverage factor' that is close to one.

Animals↗
PubMed1990

Convergence and divergence of cones onto bipolar cells in the central area of cat retina.

In the central area of cat retina the cone bipolar cells that innervate sublamina b of the inner plexiform layer comprise five types, four with narrow dendritic fields and one with a wide dendritic field. This was shown in the preceding paper (Cohen & Sterling 1990 a) by reconstruction from electron micrographs of serial sections. Here we show by further analysis of the same material that the coverage factor (dendritic spread x cell density) is about one for each of the narrow-field types (b1, b2, and b4). The same is probably true for the other narrow-field type (b3), but this could not be proved because its dendrites were too fine to trace. The dendrites of types b1, b2, and b4 collect from all the cone pedicles within their reach and do not bypass local pedicles in favour of more distant ones. The dendrites of type b5, the wide-field cell, bypass many pedicles. On average 5.1 +/- 1.0 pedicles coverage on a b1 bipolar cell; 6.0 +/- 1.2 converge on a b2 cell and 5.7 +/- 1.5 converge on a b4 cell. Divergence within a type is minimal: one pedicle contacts only 1.2 b1 cells, 1.0 b2 cells, and 1.0 b4 cells. Divergence across types is broad: each pedicle apparently contacts all four types of the narrow-field bipolar cells that innervate sublamina b. Each pedicle probably also contacts an additional 4-5 types of narrow-field bipolar cell that innervate sublamina a. There are several possible advantages to encoding the cone signal into multiple, parallel, narrow-field pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Neurohormones regulate T cell function.

In this communication we show that T cell locomotion is affected by direct interaction with neurohormones. Opioid peptides, including beta-END, MET-ENK, LEU-ENK, and related enkephalin analogues enhanced migration of human peripheral blood T lymphocytes. Activity was dependent on the peptide NH2-terminal sequence, stimulated by enkephalin analogues with specificity for classical delta or mu types of opiate receptor, and inhibited by the opiate receptor antagonist naloxone. Our studies suggest that such neuropeptides stimulate T cell chemotaxis by interaction with sites analogues to classical opiate receptors. We propose that the endogenous opioids beta-END, MET-ENK, and LEU-ENK are potent immunomodulating signals that regulate the trafficking of immune response cells.

Amino Acid Sequence↗
PubMed1990

Expression of completely gamma-carboxylated and beta-hydroxylated recombinant human vitamin-K-dependent protein S with full biological activity.

Human anticoagulant vitamin-K-dependent protein S was expressed in mouse C127 cells using a bovine papilloma virus vector system. A full-length cDNA construct was introduced into the vector in the 5' untranslated region of the mouse metallothionein-I gene. Transfected cells expressed approximately 10 micrograms/ml of the recombinant protein which was purified by ion-exchange chromatography followed by affinity chromatography using Ca2(+)-dependent monoclonal antibodies against the region of protein S containing 4-carboxyglutamic acid. Recombinant protein S was structurally and functionally similar to protein S purified from plasma. On SDS/polyacrylamide-gel electrophoresis recombinant protein S had a slightly higher molecular mass than plasma protein S. After treatment with endoglycosidase F, the proteins comigrated suggesting the observed molecular mass difference to be due to alterations in the N-linked carbohydrate side chains. Recombinant and plasma protein S demonstrated identical amino-terminal sequences, similar amino acid composition and number of 4-carboxyglutamyl and 3-hydroxyaspartyl/asparaginyl residues. Recombinant protein S had the same affinity for Ca2+ as protein S from plasma and the two proteins had the same activated protein C cofactor activity in a functional assay. In addition, both forms of protein S formed complexes with C4b-binding protein with the same apparent Kd. Protein S is the most extensively post-translationally modified vitamin-K-dependent protein, and all the modifications were carried out in the recombinant DNA system yielding a recombinant protein S with full biological activity.

Amino Acid Sequence↗
PubMed1990

Syndrome of brittle cornea, blue sclera, and joint hyperextensibility.

In 3 families 4 patients were affected with the syndrome of brittle cornea, blue sclera, and hyperextensible joints (brittle cornea syndrome). From the review of 17 affected patients described previously and our cases, it appears that this rare autosomal recessive syndrome has variable expressivity. Two different groups of patients may be distinguished: one includes 5 families, all of Tunisian Jewish origin. All patients in this group also have red hair. In the second group, 9 families are from various ethnic origins; affected patients in this group have a normal distribution of hair color. A possible explanation for the existence of these 2 different group of patients is that the locus of the gene responsible for the syndrome is closely linked to the locus for a gene responsible for hair color with linkage disequilibrium in Tunisian Jews (Sepharadim).

Corneal Diseases↗