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Biomedical subjects

J Cohen

Publications and source records attributed to J Cohen.

At least 1,387 records · Page 77Linked to original sources
PubMed1981

In vitro fertilizing capacity of fresh and cryopreserved human spermatozoa: a comparative study of freezing and thawing procedures.

The capacity of human spermatozoa to penetrate zona-free hamster ova was used to investigate several methods of freezing and thawing sperm. No differences in postthaw sperm viability were obtained after cooling spermatozoa either with a complex egg yolk cryoprotective medium or glycerol. The in vitro fertilizing capacity of postthaw spermatozoa frozen with a moderate freezing rate was similar to that of spermatozoa frozen with a slow freezing rate. Significantly higher in vitro fertilization percentages were found when the spermatozoa were thawed at an environmental temperature of 22 degrees C (mean 51%) or 37 degrees C (mean 52%), as compared with spermatozoa thawed at 4 degrees C (mean 37%). Individual differences of in vitro fertilization percentages are discussed in relation to changes in motility. It is demonstrated that a high prefreeze in vitro fertilization percentage is no guarantee of a high postthaw fertilizing ability.

Animals↗
PubMed1981

Hormones and midbrain mediation of courtship behavior in the male ring dove (Streptopelia risoria).

The nucleus intercollicularis (ICo) region of the midbrain has been shown to concentrate testosterone and to be involved in the neural control of avian vocal behavior. The present study investigated the possible role of the ICo region in the androgen-dependent courtship behavior of male ring doves, with the use of radio-frequency lesion and intracranial hormone-implant techniques. In the first experiment, bilateral lesions in the ICo region reduced nest-cooing but did not specifically alter other courtship behavior of males tested with stimulus females. No effect on gonadal state could be discerned. In a second experiment, unilateral 30-ga. implants containing crystalline testosterone propionate (TP) or cholesterol (C) were placed in the ICo region or in other parts of midbrain of castrated male doves. The TP implants activated nest-cooing when placed in the ICo region only. Other behaviors were not elicited or not selectively affected by TP implants. Diffusion from the implant was probably not responsible for the elicitation of nest-cooing, since the weights of the peripheral steroid-sensitive tissues of males implanted with TP and C did not differ and since many sites near, but not in, the ICo region were ineffective. These data demonstrate the importance of the ICo region in the expression of nest-cooing, vocal courtship behavior, in the male ring dove. Furthermore, the facilitation of certain vocal courtship behavior by hormonal stimulation is in line with the suggestion that the central gray/ICo/torus semicircularis regions of the vertebrate brain are analogous in their mediation of vocalizations.

Animals↗
PubMed1981

A selected review of retinal research and study.

Fifty papers were selected from the American and British Journals of Ophthalmology and the Archives of Ophthalmology from July 1978 to June 1979. Topics include retinal pigment epithelium, retinitis pigmentosa, diabetic retinopathy, toxoplasmosis, and histoplasmosis. Also, other retinopathies, maculopathies, retinoblastoma, retrolental fibroplasia, and retinal breaks, holes, and detachments were included.

Adolescent↗
PubMed1981

Feedback on prekindergarteners failing vision screenings.

This study is a sequel to an earlier report on a random vision screening of 651 prekindergarteners and compares the findings of the 35 children who failed this screening with the results and dispositions after retesting. Of the number failed, 32 (91.4%) were accounted for, of whom 28 (80%) were retested and 14 (40%) received no treatment; the other 4 (11.4%) were not retested. A discourse on probable discrepancies between screening and retesting results follows, along with corrective recommendations.

Adolescent↗
PubMed1981

Alleviation of experimental ischemic acute renal failure by dimethyl sulfoxide.

Acute, ischemic renal failure was induced in rats by clamping of the renal vessels for 1 h. Following the termination of the ischemic period 5 g/kg of dimethyl sulfoxide (DMSO) were administered intravenously as a 20% solution in saline. Control animals received normal saline. There were not deaths among the DMSO-treated animals. Urine flow began within 15 min of DMSO infusion. 24 h after the experiment the mean blood urea was 73 +/- (SEM) 14 mg/100 ml (n = 29). All the control rats died during the week following the experiment. The mean blood urea at 24 h was 276 +/- 18 mg/100 ml (n = 20). In 10 additional animals perfusion of the kidney with DMSO prior to the closure of renal vessels protected the organ from ischemic damage. These experiments have a bearing on the therapeutic approach to ischemic renal failure in man, and on preservation methods of donor kidneys for transplantation.

Acute Kidney Injury↗
PubMed1981

Neuroleptic drugs activate tyrosine hydroxylase of retinal amacrine cells.

Tyrosine hydroxylase of retinal dopamine-containing amacrine cells exists in two states, a basal state in the dark and an activated state in the light. Treatment with haloperidol, chlorpromazine, clozapine or domperidone results in activation of tyrosine hydroxylase in the dark. With haloperidol, the magnitude of the activation was dose-related. After a single dose of haloperidol (3 mg/kg i.p.) enzyme activation persisted for at least 3 hr. By kinetic analysis, activation was characterized as a decrease in the Km for the pteridine cofactor. Activation by light induces similar kinetic changes. Apparently, the dopaminergic system of retina responds to neuroleptic drug treatment similar to that nigrostriatal dopaminergic system.

Adaptation, Physiological↗
PubMed1981

[Effects of psychotropic drugs on testicular and ovarian function and reproduction (author's transl)].

Many psychotropic drugs induce changes in the menstrual cycle, Spermatogenesis fertility and sexual behaviour. The data in the published literature is reviewed, employing the classification of these drugs into three groups; depressants stimulants, and modifiers of central nervous system activity. The information available suggests that these drugs effect male and female gonadal function, but demonstrative studies are still lacking.

Antidepressive Agents↗
PubMed1981

Interferon activity in rotavirus infected newborn calves.

A viral inhibitor displaying the main properties of a type 1 (alpha or beta) interferon was found in intestine and serum of diarrheic newborn calves following oral administration of bovine rotavirus. Other internal organs examined 24 hours after infection all contained appreciable amounts of interferon. A kinetic study performed in ileum and serum of a one day-old calf showed a good time correspondence between peak levels of virus multiplication in the gut, intestinal interferon, and systemic interferon. In the same experiment, a two week-old calf was refractory to the disease, developing much delayed and weaker productions of both virus and interferon, when compared to the newborn calf. Therefore, the enhanced susceptibility of the newborn calf to rotavirus induced diarrhea is not related to a deficiency in interferon synthesis.

Animals↗
PubMed1981

[Adaptation of an isolate of bovine enteritic coronavirus to serial growth in cell culture and characterization of the virus (author's transl)].

Coronaviruses are known to behave as pathogens in a variety of animal species. Their multiplication in the differentiated enterocytes of the intestinal tract induces a severe diarrheic syndrome which may lead to death. To study these viruses and to progress in the development of prophylactic and diagnostic methods, it is essential to succeed in adapting the agents to serial growth in cell culture. In spite of several attempts adaptation to primary cell cultures could be obtained in the past only for two isolates. The present work describes the methodology which enabled us to succeed in the adaptation of a bovine enteric coronavirus isolated in France to primary calf kidney cells, and reports results on the characteristics of this virus. Adaptation to serial growth was realized at 34 degrees C in the following way: 3 passages each lasting 8 to 10 days followed by 16 passages each lasting 6 days. From the 20th passage on the duration of incubation was reduced to 4 days. Virus growth was checked using an indirect immunofluorescence test. During the first passages only a few dispersed positive cells could be observed but later on small foci of immunofluorescent cells did appear. By the 35th passage infective titers did not exceed 1 x 10(5) TCID50/ml and cytopathic effects were always very discrete. When the susceptibility of different cell-types to this coronavirus strain (G110) was checked we found that only bovine cells and the human HRT18 cell-line were able to replicate the virus. In HRT18 cells titers as high as 5 x 10(7) TCID50/ml could be obtained at the first passage of G110 strain, previously adapted to primary calf kidney cells. As regards the antigenic properties of G110 virus no difference could be established between this strain and the Nebraska isolate (NCDCV) neither by indirect immunofluorescence test nor by indirect neutralization test. The G110 strain agglutinates rat and mouse erythrocytes. The density of purified virions in mouse gradients is 1.19 and the morphology of the particles is characteristic of a coronavirus.

Animals↗
PubMed1981

[Triatoma infestans as a vector of hepatitis B virus].

Mosquitoes and bed bugs may play a role in the transmission of hepatitis B virus (H.B.V.). We investigated this possibility with the Triatoma Infestans, which is a hematophagous insect widely prevalent in the Argentine Republic. Triatoma Infestans fed with serum or blood contaminated with H.B.V. were studied at 7, 14, and 21 days after contamination. Stool and insect homogenates were positive for HBsAg at each time checked. Considering the domestic habits and hematophagous condition of Triatoma Infestans, we feel that this insect could also play a role in the transmission of H.B.V. through their bites or dejections.

Animals↗
PubMed1981

Screening results on the ocular status of 651 prekindergarteners.

During the fall and winter of 1978, 651, two-, three-, and four-year-old prekindergarten children were randomly screened to determine their ocular status. The criteria for passing these tests were less critical than those used for primary grade students. Nevertheless, the screening program embraced fairly comprehensive histories, visual acuities, and external and ophthalmoscopic examinations, including extraocular muscle coordination, cover tests, and static retinoscopy. Of these children, 82.8% were black. Only the black group was large enough to constitute an adequate sample, therefore this report deals principally with 524 black 3- and 4-year olds. Most of the findings were within the set limits. One feature of the program was the observation of the behavioral differences in these children.

Age Factors↗
PubMed1980

A preparation enriched in Purkinje cells identified by morphological and immunocytochemical criteria.

A preparation highly enriched in isolated Purkinje cell perikarya was obtained from the developing rat cerebellum. The technique, which also yields a fraction enriched in differentiated astrocytes, involved the removal of heterogeneously-sized replicating cells in vivo by treatment with hydroxyurea prior to dissociation of cells with mild trypsinization and fractionation by sedimentation at unit gravity. Fractions were monitored in terms of particle size and by light and electron microscopy. Pooled fractions containing at least 50% perikarya of > 14.5 micron diameter were enriched in cells resembling Purkinje neurons. Definitive identification of these cells was obtained using an antiserum specific to Purkinje cells. In immunocytochemical studies about 80% of the cells in the fraction enriched in large cells reacted with the antiserum vs about 4% in the unfractionated cell suspension, whilst most of the other cells were identified as astrocytes containing glial fibrillary acidic protein.

Animals↗
PubMed1980

Direct evidence of sudden rise in fetal corticoids late in human gestation.

Glucocorticoids accelerate fetal lung maturation in all mammals studied, and in some species, such as goat and sheep, concentrations of fetal cortisol increase sharply before term, bringing about a train of events leading to parturition. Studies of cortisol in the umbilical cord blood have revealed no such increase at the end of human pregnancy. But information obtained in that way is difficult to interpret because much of the fetal cortisol is of maternal origin and its concentration, if sampled at delivery, is affected by maternal stress. These problems can be avoided to some extent by studying other fetal corticoids. Corticosterone sulphate (once called compound B, and abbreviated to BS) is produced by fetal adrenal glands and is present in greater concentrations in human fetal plasma than in maternal plasma. It is hydrolysed by the placental sulphatases and is a poor substrate for for placental 11 beta- hydroxysteroid dehydrogenase. We report here confirmation that the bulk of maternal BS originates from the fetus, and that its concentration increases suddenly at term.

Adrenal Glands↗
PubMed1980

Cloning and sequence of the cDNA corresponding to the variable region of immunoglobulin heavy chain MPC11.

Poly(A)-containing mRNA from mouse myeloma MPC11 was transcribed into cDNA which was cloned in the PstI site of the plasmid pBR322. The transformants were screened by hybridization with a cDNA fragment, derived from plasmid p gamma(11)7, corresponding to the 5' portion of the constant region of MPC11 heavy chain. Several positive transformants were found to contain various lengths of the variable region of the heavy chain. We describe the structure and sequence of one of these clones, pV(11)2, which contains cDNA corresponding to the entire variable region of MPC11 heavy chain and extends to codon 248 in the constant region. The protein sequence deduced from the DNA sequence indicates that the variable region of MPC11 heavy chain contains 121 amino acids and belongs to subgroup II of mouse heavy chains. Comparison of this sequence with other heavy chain sequences suggests a J (joining) segment of 16 residues which overlaps five residues of the third hypervariable region. The cDNA sequence shows that there is no discontinuity between the end of the variable region and the beginning of the constant region.

Animals↗