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Biomedical subjects

S Cohen

Publications and source records attributed to S Cohen.

At least 541 records · Page 30Linked to original sources
PubMed1989

The nature of the defect in familial male pseudohermaphroditism in Arabs of Gaza.

Studies in six Arab individuals from Gaza with familial male pseudohermaphroditism (MPH) due to 17-ketoreductase deficiency revealed several metabolic aberrations associated with the disorder. Plasma LH, FSH, testosterone, and androstenedione concentrations were low in the two prepubertal patients. After hCG administration plasma androstenedione increased markedly. The four postpubertal MPH patients had very high plasma gonadotropin and androstenedione concentrations, the latter increasing further after hCG administration. Plasma testosterone concentrations in all six patients were moderately low or normal for age and increased little after hCG administration. Spermatic venous testosterone concentrations, measured in three adults, were within the normal range in two and low in one, while androstenedione concentrations were markedly elevated (15- to 32-fold) in all three patients. Kinetic analyses of progesterone and androstenedione metabolism were performed in testicular tissue of these patients and compared to the results in two control subjects. While testicular tissue from the two prepubertal patients metabolized progesterone only to androstenedione, and that to a limited extent, the tissue from the four postpubertal patients metabolized progesterone to 16 alpha- and 16 beta-hydroxyprogesterone, 17 alpha-hydroxyprogesterone, androstenedione, and testosterone and metabolized androstenedione to testosterone. The Michaelis constants of these reactions were similar in the tissue from the MPH and the control subjects. The production of 16 alpha- plus 16 beta-hydroxyprogesterone was 5.4- to 10.3-fold greater, and 17-hydroxylase activity was 5.8- to 8.1-fold lower in the testes of the postpubertal MPH patients compared to values in the control subjects. The preference of androstenedione production through the delta 4- or delta 5-pathways was examined in the testes of two adult MPH patients using an equimolar concentration of [14C]progesterone and [3H]pregnenolone as substrates. While the flow of substrates in the control testes was equal or slightly greater through the delta 4-pathway, the delta 5-pathway predominated in the testes of the MPH patients. A large amount of dehydroepiandrosterone accumulated when NAD, the cofactor for 3 beta-hydroxysteroid dehydrogenase-isomerase, was omitted, supporting the contention that androstenedione was produced in the testes of the MPH patients mainly through the delta 5-pathway. Additional support for this suggestion was the finding that the 3H/14C ratio in androstenedione and testosterone produced from both substrates was 8 times higher in the testes from MPH patients than in those from the control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

17-Ketosteroids↗
PubMed1989

Expression of an intercellular adhesion molecule, ICAM-1, by human thyroid cells.

Intercellular adhesion molecule-1 (ICAM-1), hitherto identified on activated B cells, macrophages, dendritic cells, endothelia and certain epithelial cells, serves as a ligand for the lymphocyte function-associated antigen-1 (LFA-1). ICAM-1 binding by LFA-1 enhances the efficiency of lymphocyte-target cell and lymphocyte-accessory cell interactions. We have investigated the in-vitro expression of ICAM-1 by cultured thyroid cells from five patients with Graves' disease using indirect immunofluorescence analysis, and found that 30 +/- 11% (mean +/- S.D.) of cells were ICAM-1 positive under basal conditions. The proportion of cells which were ICAM-1 positive and the amount of ICAM-1 per cell (assessed by fluorescence intensity) were both increased in all cases by the cytokines gamma-interferon, interleukin-1 and tumour necrosis factor. Immunohistochemical analysis of frozen sections from thyroidectomy specimens demonstrated ICAM-1 on thyroid follicular cells in areas of lymphocytic infiltration in patients with Graves' disease (n = 2) or Hashimoto's thyroiditis (n = 2). ICAM-1 was not found in specimens from a patient with a toxic multinodular goitre or a patient with Graves' disease without focal lymphocytic accumulation. These results suggest that the thyroid epithelium may express ICAM-1 as well as major histocompatibility complex class II antigens, such as HLA-DR, in response to locally synthesized cytokines. The enhanced expression of ICAM-1 may render these cells more susceptible as targets for lymphocyte-mediated cytotoxicity, and together with HLA-DR antigen expression may increase the accessory cell capability of the thyroid follicular cells.

Antigens, Surface↗
PubMed1989

[Clinical aspects of endotheliotropic (hemolytic) nephroangiopathy].

Clinical syndromes as hemolytic-uremic-syndrome, thrombotic-thrombocytopenic-pupura and primary-malignant-hypertension not only present multiple clinical but also etiological and pathogenetical common characteristics. Thoenes and John developed in 1980 the unifying concept of endotheliotropic (hemolytic) nephroangiopathy for these diseases which are characterised by pathologic interaction between damaged endothelial cells and erythrocytes. This concept was increasingly discussed and accepted in the literature during the course of the last years. We describe the clinical manifestation of the subgroupes which were defined by Thoenes and John according to the vascular pattern of pathomorphologic intrarenal lesions. It can be shown that the classification based on pathomorphologic findings is very useful for the differentialdiagnostic characterisation and the prognostic evaluation in a given single case.

Endothelium, Vascular↗
PubMed1989

Swine cysticercosis treated with praziquantel, a short report.

Swines with cysticercosis are a useful model to study human disease. A multidisciplinary approach was undertaken to study in detail the effect of praziquantel treatment on hosts and parasites. Computerised tomographic scans showed changes in the number and size of parasites in treated pigs. These changes were more apparent in muscle than in brain cysticerci. Neurophysiologic data were normal in cysticercotic pigs before and after drug treatment. An increase in antibody response was seen immediately after treatment regarding the amount of antibodies and number of antigens recognised. A lower number of polyploid lymphocytes was seen after treatment in cysticercotic pigs as compared to untreated pigs. At different times after treatment pigs were humanely euthanised. Oxygen consumption rate of cysticerci decreased after treatment and evagination was abolished. The inflammatory reaction that surrounded parasites increased in number and type of cells. This was more apparent around cysticerci obtained from muscle than from the brain.

Animals↗
PubMed1989

Massive pseudophakic pigment dispersion associated with an iris nevus.

A 67-year-old woman examined 12 months following extracapsular cataract extraction had a massive pseudophakic pigment dispersion associated with diffuse corneal epithelial edema, mild uveitis, and secondary glaucoma. She underwent penetrating keratoplasty following removal of a posterior chamber intraocular lens (IOL), anterior vitrectomy, capsulectomy, and iris biopsy. Histopathologic examination revealed a pigmented iris nevus and signs of iris erosion by the IOL loop. Because 3 months later the eye developed streptococcal endophthalmitis and had to be eviscerated, we had the opportunity to examine the eye contents; we found no evidence of phakoanaphylactic uveitis.

Aged↗
PubMed1989

Gastroesophageal reflux disease: new concepts in pathophysiology.

The explanation as to why gastroesophageal reflux disease develops remains unanswered. We have learned much about the regulation of LES pressure, the single most important factor in the development of reflux disease. Our understanding of factors involved in the clearance of refluxed contents has also increased. The presence of reflux in the postprandial period and with belching suggests that it is serving a physiologic function. This may be a response to increases in gastric volume or pressure accompanying these situations. The question that has not been satisfactorily answered is what factor is responsible for the progression of a physiologic phenomenon to a pathologic condition. The answer to this question lies in the development of more physiologic techniques for monitoring LES pressure changes and a better understanding of the neural and hormonal pathways that regulate lower esophageal sphincter tone.

Adaptation, Physiological↗
PubMed1989

Bidirectional interaction between the central nervous system and the immune system.

We believe that any questions regarding whether the CNS can alter immune system functions no longer remain. It can conclusively be stated that the immune system is susceptible to influences of the CNS. It remains to be determined whether all classes of lymphocytes, NK cells, macrophages, polymorphonuclear leukocytes, and other antigen-processing cells are all susceptible to CNS influences. We have presented evidence that peripheral blood lymphocytes may not reflect the immunological activity of lymphocytes within lymphatic tissue after being influenced by a stressor. Thus, all types of immunological cells must be evaluated in different organs. Whether the immune system of young and old animals respond in the same way must also be determined. The sex of the animal needs to be taken into consideration. What immune responses are important to measure? Do in vitro responses reflect the ability of an animal to resist infectious disease or susceptibility to autoimmune and malignant diseases? Certainly, absence of an immune response is detrimental to health. It must be determined whether moderately suppressed immune function in multiple compartments is as detrimental as total absence of an immune response in a single immunological compartment. The data that we have presented with respect to adjuvant arthritis indicate that an immune response in the peripheral of the animal can be modified by a stressor and influence an immunopathological process. This may indicate that the most important immune compartment to evaluate with respect to altering disease susceptibility is the peripheral blood and that lymphoid tissue may be interesting, but not clinically relevant. The reasons why the peripheral blood and lymphoid tissue differ in their immunological function following exposure to a stressor must be determined. We have reviewed information indicating that lymphoid tissue is innervated and that such innervation can modify immune function. In addition, hormones released by the CNS may alter immune function. Yet, much of this data are contradictory and whether immune enhancement or suppression occurs is not clearly defined with respect to any experimental manipulation involving denervation or the addition of hormones to in vitro cultures. Whether this reflects the age of the experimental animal, the type of immune response being measured, the adequacy of the experimental procedure, background rearing conditions of the animals, the amount of noise in the animal room, the diet of the animals, or the number of animals housed per cage all remain to be determined. Our purpose has not been to provide a comprehensive review of all of the data relating to the immune system/CNS interaction.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Medical student, resident, and faculty use of a computerized literature searching system.

The experiences of medical students, residents, and faculty with a computerized literature searching system were evaluated. Third-year medical students, internal medicine and family practice residents, and full-time and voluntary faculty at one medical school had the opportunity to use a full-text and bibliographic medical literature retrieval system free of charge for an eleven-month period. Subjects conducted nearly nine thousand literature searches over a period of 942 system hours. Questionnaire data showed that participants could learn to use and would use an electronic information system, felt capable of using the system, utilized the system for a variety of purposes and in a number of different ways, and viewed the system as a valuable tool in searching the medical literature. The results are discussed in the context of the educational needs of the four user-groups and medical education planning by institutions.

Computer User Training↗
PubMed1989

Immunohistochemical analysis of the retrobulbar tissues in Graves' ophthalmopathy.

We have characterized the mononuclear cell infiltrate in the extraocular muscle of three patients with Graves' disease, using antibodies which permit staining of paraffin-embedded tissue. The majority of lymphocytes, occurring in foci or interstitially, were T cells, most of which stain for CD3 or with UCHL1. T cells few, if any, stained with SN130, directed against the CD45R determinant. This suggests that these lymphocytes comprise a recently activated population within which memory cells may reside. B cells were also found but were predominantly confined to focal aggregates, and in one patient lymphoid follicles were seen. The orbital fat and connective tissue from a further two patients contained very few infiltrating cells which were mainly UCHL1-positive. Eye muscle cells did not express Ia antigens but the interstitial cells between them were Ia-positive and the vascular endothelium in four of the five specimens also stained with Ia. These results indicate that Graves' ophthalmopathy is associated with T cell, and to a lesser extent B cell, responses against the retrobulbar tissues; the extraocular muscle interstitial cells, probably including fibroblasts, may be targets of activation resulting from this infiltration.

Adult↗
PubMed1989

Characterization of the antigen-reactive T cell line mediating in vivo delayed type hypersensitivity established by antigen-induced interleukin 2.

The murine antigen-reactive T cell line has been established by antigen-induced interleukin 2 (IL-2) derived from immunized syngeneic mice. The surface markers of the cells showed Thy 1+, and Lyt 1+2-. The antigen-reactive cells require the presence of IL-2 for continuous proliferation. IL-2 from mouse, rat, or human sources all stimulate the T cell line growth. The T cell mitogen such as concanavalin A and antigen alone do not stimulate cell proliferation of the cells. The cells proliferate antigen-specifically in the presence of both IL-2 and antigen-presenting cells from histocompatible mice. Antigen-specific in vivo delayed type hypersensitivity response is inducible by injection of the T cells into naive syngeneic mice along with IL-2 and antigen. The reactivity of the T cell line found in vitro (proliferation) and in vivo (delayed type hypersensitivity) is highly antigen-specific, because the cells do not respond another antigen used for immunizing mice. The antigen-reactive T cell line produces neither IL-2 nor inhibiting factors such as neutralizing factors against preformed IL-2 activity and IL-2 production inhibiting factors, thus the cells are exclusive IL-2 acceptor. These results suggest that the interaction of antigen-induced IL-2 and IL-2 dependent antigen-reactive T cells may play a significant role in the induction/expression of in vivo delayed type hypersensitivity to specific antigen, because antigen-induced IL-2 is probably only a relevant IL-2 in the immunized mice.

Animals↗
PubMed1989

Arthroscopy update #5. Rehabilitation after arthroscopic lateral retinacular release.

This study compares postoperative quadriceps strength with functional results in a homogeneous population with isolated anterior knee pain and patellofemoral instability. Although several factors may interfere with the success of lateral retinacular release, this study suggests that poor quadriceps rehabilitation is the single factor preventing total return to athletic participation in patients with lateral subluxation. Many patients seem to adopt changes in life-style in order to accommodate weakened quadriceps and remain symptom free.

Adolescent↗
PubMed1989

Postoperative refractive changes in children with congenital esotropia: a preliminary study.

A transient myopic inclination was found 2 months postoperatively in 23 children who had undergone surgery for congenital esotropia. Neither the age of the children at the time of surgery nor the length of muscle recession/resection influenced these refractive myopic changes. Early postoperative refractive correction with periodic follow-up is essential in preventing amblyopia. In 21 of the 23 children, visual acuity was 6/10 or better at last examination.

Child, Preschool↗
PubMed1988

Activation of a cytosolic serine protein kinase by epidermal growth factor.

Exposure of A-431 cells to epidermal growth factor (EGF) results in a rapid enhancement (approximately 10-fold) of cytosolic serine protein kinase activity. The increase in serine kinase activity may be detected using a number of peptide and protein substrates. Enhancement of kinase activity occurs within 1 min of exposure of the cells to EGF and reaches a maximum in 5 min. Similar results were obtained with a variety of cell lines. We have partially purified the EGF-activated kinase from A-431 cells. It has an apparent molecular mass of approximately 100 kDa by gel filtration. One distinguishing property of the enzyme is its sensitivity to inhibition by micromolar quantities of polyarginine; polylysine has no effect. The EGF-activated kinase is unaffected by cyclic nucleotides, Ca2+/calmodulin, Ca2+/diolein/phosphatidylserine, or heparin. The enhancement of cytosolic serine kinase activity in A-431 cells appears to be an early event in cell "activation" by a number of biological response modifiers including EGF, bradykinin, 12-O-tetradecanoylphorbol-13-acetate, and histamine.

Animals↗