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Biomedical subjects

S Horowitz

Publications and source records attributed to S Horowitz.

At least 163 records · Page 9Linked to original sources
PubMed1978

Preferential charging of tRNA-Met-f in Escherichia coli K12.

The charging of tRNA-Met-f and tRNA-Met-m in vivo and in vitro and initiation of polysomes during methionine limitation were studied in two strains of Escherichia coli K12. In the wild-type strain the distribution of polysomes as well as the kinetic parameters of methionyl-tRNA synthetase indicate preferential acylation of tRNA-Met-f. This preferential charging of tRNAM-et-f does not take place in a mutant strain which is also defective in initiation of polysomes during methionine limitation.

Adenosine Triphosphate↗
PubMed1977

Circulating thymic-hormone activity in congenital immunodeficiency.

Circulating thymic-hormone activity was assayed by measuring Thy 1-2 antigen induction on null lymphocytes from athymic mice incubated with human plasma or serum. Plasma from 19 normal children aged under 10 had inductive activity equivalent to 10-6-16-2 ng thymopoitin/ml. Plasma from 15 infants were severe combined immuno-deficiency, 2 of whom had appreciable immunoglobulin synthesis, and from 2 infants with DiGeorge syndrome had little or no inductive activity. Successful reconstitution with thymus or bone-marrow grafts and with red-cell infusions (if adenosine-deaminase deficiency is present) was followed by a rise in circulating thymic-hormone activity.

Agammaglobulinemia↗
PubMed1976

Reconstitution of B and T lymphocyte function in severe combined immunodeficiency disease after transplantation with thymic epithelium.

A patient with severe combined immunodeficiency has been given a transplant of thymic epithelium obtained from short-term culture of normal human thymus. 4 wk after transplantation immunoglobulin was detected and the patient now has normal levels of the three main classes. Functional antibodies of four specificities have been detected. An increase in reactivity to allogeneic cells and phytohaemagglutinin has been observed, with an increase in E rosettes; a positive delayed skin test to candida antigen is now present. The patient has shown reversal of wasting and has been free of infection for 7 months since receiving the transplant. It appears that under certain circumstances thymic epithelium reconstitutes both T and B cell functions.

B-Lymphocytes↗
PubMed1976

Chronic cytomegalovirus infection, immunodeficiency, and monoclonal gammopathy-antigen-driven malignancy?

An infant with severe combined immunodeficiency had normal numbers of lymphocytes which bore E rosette and surface Ig markers in an appropriate distribution. However, only minimal responsivity to in vitro stimulation by mitogens and allogenic cells, and none to antigens could be elicited; functional antibody responses were also nil, except to cytomegalovirus. Intrauterine-acquired cytomegalovirus may have caused his immune dysfunction, although the possibility of a postnatal infection cannot be excluded. Therapy with transfer factor and thymus transplantation was unsucessful in restoring immunity and may have aggravated a pre-existing monoclonal gammopathy. It is possible that the monoclonal protein was derived from B-cells transplacentally received from the patients mother.

Antibody Formation↗
PubMed1976

The position of the external ear in Turner's syndrome.

The cephalometric roentgenograms of persons with the syndrome of XO gonadal dysgenesis and its variants, and of those with Noonan's syndrome, were compared with a control sample of unaffected females matched for age. Posterior craniofacial relationships differ between XO and normal individuals, particularly in the region of the external auditory meatus, which is located relatively more inferiorly and anteriorly in XO gonadal dysgenesis subjects than in chromosomally normal persons. Individuals who are mosaics, and those with Noonan's syndrome, do not differ from the unaffected population to the same extent. Although the position of the auricle often changes appreciably with growth when judged by clinical criteria alone, cephalometric analysis of relative ear position may still support the diagnosis of "low-set" ears.

Adolescent↗
PubMed1975

Studies in myasthenia gravis. Pyridostigmine-C14 metabolism after thymectomy.

Pyridostigmine-carbon 14 (P-C14) excretion studies in myasthenia gravis patients who had had thymectomies failed to produce any significant difference from results observed in myasthenic patients who had not had thymectomies. Thus, change in P-C14 metabolism cannot help explain decreased anticholinesterase requirements and electromyographic changes observed in some patients following thymectomy.

Adult↗
PubMed1975

Selective IgA deficiency---some perspectives.

The clinical spectrum of IgA deficiency varies from good health to respiratory, gastrointestinal, autoimmune and malignant disorders. Evaluation of B lymphocytes with surface IgA receptors in this disease reveals cap formation, decreased to normal density of IgA receptors, and IgA secretion following pokeweed stimulation. Further study of antigen-induced B-lymphocyte phenomena is needed. The presence of decreased numbers of T-cell markers in some individuals with IgA deficiency suggests a T-"helper" cell defect.

Antibody Formation↗
PubMed1975

Transcervical thymectomy in myasthenia gravis.

Since 1967, transcervical thymectomy has been the procedure of choice for all patients with nonthymomatous myasthenia gravis and a selected group of patients with thymomatous myasthenia gravis operated upon at the Mount Sinai Hospital. A total of 180 transcervical thymectomies have been performed. In 12 patients, a pre-existing tracheostomy was present. Morbidity was minimal, limited to three instances of bleeding, five of pneumothorax, one of self-limited chylothorax, and one wound infection. One postoperative death from an unrelated cause occurred in 1967. The postoperative course has been smoother and the management of the myasthenia gravis considerably easier than those following transthoracic approaches. Consequently, routine elective tracheostomy at the time of thymectomy has been abandoned. The average period of hospitalization does not exceed one week. As a result of the minimal risk involved, indications for thymectomy now include all patients with generalized myasthenia gravis, and the procedure is performed earlier in the course of disease. Postoperative electromyographic findings show immediate improvement in the majority of patients operated upon during the first year in which symptoms occur. Transcervical thymectomy arrests the progress of the disease, decreases the mortality rate, and has long term results equal to those of transthoracic approaches. Earlier remissions, fewer germinal centers, and a smaller number of thymomas were noted in patients operated upon early in the course of the disease. A decrease in neoplasms outside the thymus gland and in neonatal myasthenia gravis was also noted following thymectomy.

Breast Neoplasms↗
PubMed1975

Influence of prolactin on carcinogen-induced leukemogenesis in Long-Evans rats.

Hypophysectomy of rats bearing 7,12-dimethylbenzanthracene-induced leukemia has been reported to result in a prompt and persistent regression of the leukemia. The purpose of this study was to determine whether or not marked alterations in prolactin secretion would influence this neoplastic process. To determine this, immature male and female Long-Evans rats were divided into three groups: Group 1, controls; Group 2, pituitary grafted (hyperprolactinemia); and Group 3, 2-bromo-alpha-ergocryptine-treated (hypoprolactinemia). Two weeks after the initial treatment and at 2-week intervals thereafter (6 total), each rat was given a single intragastric intubation of 7,12-dimethylbenzanthracene (10 mg/rat). Two months after the initial carcinogen treatment and at 2- to 3-week intervals thereafter, all rats had liver biopsies for the identification of leukemia. Results clearly show that despite nearly 10-fold difference in mean serum prolactin levels in the three groups of female rats and nearly a 20-fold difference in the level of this hormone in male rats, no significant differences in the magnitude of this leukemogenic process could be detected. Thus, striking changes in prolactin secretion do not appear to influence significantly this leukemogenic process.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1974

Small intestinal disease in T cell deficiency.

Biopsies of the proximal small bowel were obtained in four children with impairment of cell-mediated immunity, chronic diarrhia, and malabsorption; one child had an isolated T cell defect and three had significant B and T cell defects. All of them had malabsorption and, in addition to alterations of the small bowel epithelium, large vacuolated macrophages were seen in the lamina propria in all biopsies. Electron microscopy demonstrated lipid and patches of small pleomorphic inclusions within the macrophages. Since large vacuolated macrophages have also been described in Whipple's disease and chronic granulomatous disease, we suggest the possibility of a common thread of defective host defense and gastrointestinal malfunction in these three conditions.

B-Lymphocytes↗