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Biomedical subjects

J Cohen

Publications and source records attributed to J Cohen.

At least 1,063 records · Page 59Linked to original sources
PubMed1990

Absence of T cell impairments in a unique group of anal-receptive transvestite and male prostitutes in Israel.

High rates of immunologic abnormalities in asymptomatic, clinically healthy urban homosexual men have been associated with promiscuous, unprotected receptive rectal intercourse, and related to infection by the human immunodeficiency virus (HIV), Epstein-Barr virus (EBV) and cytomegalovirus (CMV). In cohort studies in Israel, which is still a low risk country for HIV infection and AIDS, about 40% of asymptomatic, clinically healthy male homosexuals consistently showed T cell defects that were not correlated with anal-receptive sexual behavior and were independent of HIV antibody status. Since pre-existing immune impairments in HIV-seronegative individuals have been implicated as a risk factor for seroconversion, we have attempted to investigate more precisely the role of anal-receptive homosexual activity as a risk factor for the acquisition of immune defects. We compared T lymphocyte profiles and mean geometric titers of EBV and CMV in a homogeneous group of 14 transvestite and male anal-receptive homosexual prostitutes with those of 77 HIV-seronegative male homosexuals who were not exclusively anally passive with multiple sex partners. While 44% of the control group showed a decrease of total T cells or their subpopulations as compared with normal heterosexual men (P less than 0.001), T lymphocyte values of the anal-receptive prostitutes were within the normal range. In the prostitutes, serum antibodies to HIV were detected in only 1 individual, to CMV in 12 of 13, and to EBV in all. Despite high mean geometric titers of antibodies to CMV (86.6) and EBV (25.8), frequent anal-receptive intercourse was not sufficient, in itself, to cause immune impairment in this unique group. The results suggest that the problem of cofactors contributing to immune deficiency in male homosexuals should be reexamined in countries with a low incidence for HIV seropositivity and AIDS.

Adolescent↗
PubMed1990

[Chromosome abnormalities of the fertilized human egg].

In vitro fertilization enabled the study of lethal (parthenogenesis) or sublethal (triploidy, monosomy and trisomy) chromosomal abnormalities in man. According to the literature, 23 to 71% of preimplantation embryos carry a chromosomal defect. Various factors, such as delayed fertilization, early embryo fragmentation or elevated maternal age (greater than 35 years) are related to an increase in the incidence of chromosomal aberrations. These data reinforce the debate on a preimplantation genetic diagnosis in order to select for transfer only viable and apparently normal embryos.

Blastocyst↗
PubMed1990

Nonsurgical management of blepharoptosis.

Ptosis of one or both eyelids is a problem which affects a small, but nonetheless significant, portion of the population. Ptosis can be managed in a variety of ways, all of which can usually bring about a resolution of the problem to varying degrees of satisfaction. Two patients who were helped significantly through the use of two non-invasive techniques are presented here. Both patients, somewhat handicapped by the ptosis, were able to return to a more normal daily routine as a result of the therapy employed. The etiology of blepharoptosis and its workup are briefly reviewed.

Adult↗
PubMed1990

Recapping needles.

Explore the source record for details and available documents.

Health Occupations↗
PubMed1989

A prospective, randomized comparison of ceftazidime and ciprofloxacin as initial empiric therapy in neutropenic patients with fever.

This study developed further clinical experience in using a single agent ("monotherapy") as empirical treatment for neutropenic patients with fever, and compared the safety and toxicity of two candidate agents, ceftazidime and ciprofloxacin. A prospective, randomized, single-center efficacy and safety comparison was conducted of intravenous ciprofloxacin, 200 mg every 12 hours, and ceftazidime, 2 g every eight hours, as initial empirical therapy in neutropenic patients with fever. Regimens were modified as necessary, guided by laboratory results and/or the clinical condition. Response was evaluated at 72 hours and at the end of the neutropenia. Toxicity was evaluated by regular clinical examination and laboratory investigations. A total of 43 patients with 51 febrile neutropenic episodes were enrolled into the study and randomly assigned to one of the two regimens. Five episodes were excluded from evaluation of efficacy because of protocol violations, leaving 46 evaluable episodes (21 ciprofloxacin, 25 ceftazidime). The two groups were well matched for risk factors for infection. There were no differences between the two groups in response rates either at 72 hours or at the end of neutropenia, although in the vast majority of patients some modification of the initial therapy was required. No patients died of uncontrolled bacterial infection. Superinfection with gram-positive cocci (often streptococci) was seen primarily in bone marrow transplant recipients who had been randomly assigned to receive ciprofloxacin. This study demonstrated that, in certain circumstances, a single antibiotic can be used successfully as initial empirical therapy in febrile neutropenic patients. In this study, ceftazidime and ciprofloxacin were generally of equal efficacy, but there appeared to be an increased incidence of streptococcal superinfection in bone marrow transplant recipients who received ciprofloxacin.

Adolescent↗
PubMed1989

General practice management of drug misusers.

Substance misuse has been with us for centuries, but society has only recently given doctors the responsibility for its treatment. The causes of drug misuse and the management of drug misusers in general practice are discussed.

Family Practice↗
PubMed1989

Several antigenic determinants exposed on the gp120 moiety of HIV-1 gp160 are hidden on the mature gp120.

Mouse mAb reactive to the HIV-1 envelope glycoprotein precursor gp160 of the HTLVIII(B) isolate were characterized in radioimmunoprecipitation and immunoblot tests with the use of HTLVIII(B) isolate as Ag. The reactivities of these mAb were also measured in a capture enzyme immunoassay and in radioimmunoprecipitation assay by using gp160 and gp120 expressed as vaccinia recombinants. Striking differences in exposure of specific epitopes were noted between the gp120 component of the gp160 precursor and the fully processed gp120 in both tests. These conformational rearrangements affecting the gp120 moiety of the HIV-1 envelope glycoprotein might have important implications on its immunogenicity.

Animals↗
PubMed1989

Major depressive disorder and immunity. Role of age, sex, severity, and hospitalization.

An association between depression and altered immunity has been suggested but has not been consistently demonstrated. We have studied 91 patients with unipolar major depressive disorder, and no mean differences were found between the patients and concurrently studied matched controls in mitogen-induced lymphocyte proliferation, lymphocyte subsets, and natural killer cell activity. There were, however, significant age-related differences between the depressed patients and controls in mitogen responses and in the number of T4 lymphocytes. In contrast to age-related increases in mitogen response and in T4 cells in controls, depressed patients did not show increased lymphocyte responses or numbers of T4 lymphocytes with advancing age. Severity of depression and hospitalization status were also associated with immune system changes. Altered immunity does not appear to be a specific biologic correlate of major depressive disorder but may occur in subgroups of depressed patients.

Adolescent↗
PubMed1989

Monospermy and polyspermy after partial zona dissection of reinseminated human oocytes.

Partial zona dissection (PZD), a zona drilling method that uses mechanical force to open the zona pellucida while the oocyte is shrunken in a sucrose solution, was applied to 121 unfertilized 1-day-old mature human oocytes prior to reinsemination. The 115 surviving oocytes were divided into three groups in which the duration between sucrose addition and reinsemination was varied: I) Less than 20 minutes, II) 21 to 45 minutes, and III) longer than 45 minutes. There was a trend toward a reduced fertilization and polyspermy rate as the time between sucrose exposure and insemination in sucrose-free medium increased. Moreover, there was a statistically significant reduction in the number of oocytes penetrated by more than four sperm in group III (0/41) versus group I (7/34), and in group III, parthenogenetic development was observed. The incidence of polyspermy was also increased in oocytes manipulated more than 25 hours after retrieval compared with those manipulated 21-24 hours after recovery, supporting the idea that aged oocytes have a reduced ability to block polyspermy. Oocyte contraction in sucrose occurred in three different patterns: spherical, pear-shaped, and crenated. Both the fertilization and polyspermy rates were significantly higher in the crenated group. These results indicate that changes resembling activation occur following sucrose exposure and that sucrose activation can be used to reduce the risk of polyspermic fertilization in zona drilling procedures. In addition, the pattern of shrinkage in sucrose can be used as an indicator of oocyte receptivity to sperm penetration.

Cell Membrane↗
PubMed1989

Blastocyst formation and hatching in vitro following zona drilling of mouse and human embryos.

Hatching in vitro was studied following zona drilling of 507 two-cell mouse embryos using three methods: 1) acidic Tyrode's (AT), 2) partial zona dissection (PZD) using a sharp microneedle, and 3) zona chiseling (CH), using a large beveled needle. PZD and CH were performed while the embryos were kept in a sucrose/PBS solution. Hatching was compared to 191 unmicromanipulated controls. The incidences of cavitation and completion of hatching did not differ between groups, however more micromanipulated embryos (20-25%) hatched partially than controls (9%). The zona pellucida thinned in 59/59 (100%) control blastocysts during expansion, but in only 3/205 (2%) micromanipulated blastocysts. The hatching gap was wide in all control embryos, but smaller in 96/129 (75%) micromanipulated embryos. Partially hatched blastocysts with a "figure-8" shape were found in 59/129 (46%) micromanipulated embryos and in none of the 39 hatching controls. Hatching usually occurred a day earlier in micromanipulated embryos as 214/218 (98%) had started extruding on day 5 as compared to 20/59 (27%) control blastocysts. Fifty percent of 1-day-old human oocytes were fertilized following PZD and reinsemination and 15/31 (48%) were monospermic. Thirteen monospermic embryos cleaved, six compacted and four cavitated--of these, three extruded through the PZD incision upon expansion. The zonae did not thin and one blastocyst twinned spontaneously as it was caught between the thick ridges of the PZD hole. Results indicate that the hatching process is abnormal following zona drilling; more embryos start hatching, extrusion occurs earlier, and many become trapped which may lead to artificial twinning or the formation of trophoblastic vesicles.

Animals↗
PubMed1989

Comparison of single-shot localization methods (STEAM and PRESS) for in vivo proton NMR spectroscopy.

Two single-shot localization techniques, STEAM and PRESS, are analyzed with regard to specifications for in vivo localized proton NMR. In particular, attention is paid to optimum signal intensity per unit volume, sensitivity to motion and diffusion, shortest attainable echo time, water suppression and editing possibilities. Experimental results are shown for cat brain at 4.7 T and human brain at 1.5 T. Both STEAM and PRESS are highly effective localization methods. For long echo times, PRESS is the method of choice, because it offers a factor of two gain in signal intensity. In addition, the method is less sensitive to motion and diffusion, and not susceptible to multiple-quantum effects. STEAM offers advantages for observation of (coupled) metabolites with short T2, because (a) shorter TEs can be attained and (b) effective water suppression sequences can be implemented without penalty in echo time. Differences relating to editing possibilities and B1 dependence, possibly important in choosing a method, are discussed.

Animals↗
PubMed1989

Bronchoalveolar lavage in an immunosuppressed rabbit model of invasive pulmonary aspergillosis.

A rabbit model of invasive aspergillosis has been used to investigate the pathogenesis of Aspergillus infection in the immunosuppressed host. The animals received hydrocortisone daily and a single dose of cyclophosphamide 2 days prior to intratracheal instillation of conidia from Aspergillus fumigatus. Bronchoalveolar lavage (BAL) was performed in 3 infected and 2 control saline treated animals sacrificed on days 1, 2, 4, 7 and 10 following inoculation. Infective load within the lung was quantified using an assay for chitin which is an important component of fungal cell walls (in particular the hyphal cell wall) and is not present in vertebrate tissue. The total BAL white cell count did not discriminate between infected and saline treated animals and Aspergillus was cultured from one lavage specimen only. Infected animals developed a marked neutrophil alveolitis by day 2 in contrast to a near total absence of neutrophils in the lavages of the control animals. Phagocytosis of conidia by alveolar macrophages was prominent but did not prevent progressive infection as confirmed by measurement of lung chitin. This pattern of cellular response within the alveolar airspace reflects the complex nature of the response to Aspergillus infection in the immunosuppressed host.

Analysis of Variance↗