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Biomedical subjects

S Segal

Publications and source records attributed to S Segal.

At least 523 records · Page 29Linked to original sources
PubMed1979

Participation of a histamine-Sepharose-adherent subpopulation of human mononuclear cells in the production of leucocyte migration inhibition factor (LIF) in healthy children.

The separation of mouse splenic T lymphocytes into distinct subpopulations by fractionation on histamine-rabbit serum albumin Sepharose (H-RSAS) columns has been described. The H-RSAS-adherent T cells have been attributed regulatory functions associated with B cell activity, T cell-mediated cytotoxicity and the secretion of mediators such as immuno-interferon. The possibility that H-RSAS-adherent T cells exert a similar regulatory effect on an in vitro parameter of T cell-mediated immunity was investigated by assaying the production of leucocyte migration inhibition factor (LIF) in human blood samples, using the agarose droplet method. Phytohaemagglutinin (PHA) and BCG-purified protein derivative (PPD) were used as stimulants of LIF secretion which was measured as a percentage of inhibition of linear leucocytic migration. In normal individuals a highly significant (P less than 0.001) decrease was demonstrated in the production of LIF by peripheral blood leucocytes depleted of H-RSAS-adherent cells. Migration inhibition dropped from 36 +/- 11.7% to 21.2 +/- 12.9% in eighteen cases tested with PHA and from 29.3 +/- 11.7% to 17.2 +/- 9.8% in twelve cases tested with PPD. These results suggest the existence of a lymphocytic subpopulation involved in LIF production which expresses histamine receptors.

Cell Adhesion↗
PubMed1979

The use of donor mucus and insemination for cervical factor.

In a case of infertility due to cervical factor, application of donor mucus into the cervical canal was effective. The donor mucus with the first fraction of the husband's split ejaculate were incubated at 37 degrees C for 20 minutes. The mucus was then introduced into the cervical canal and a cervical cap for insemination was applied. A positive postcoital test was demonstrated after 6 hours. The patient conceived following a second such treatment. Donor cervical mucus aplication and insemination seem to be of value in the treatment of cervical factor.

Adult↗
PubMed1979

Thyroid function in hemodialysis.

The relevance of the biochemical evidence of hypothyroidism in patients on regular hemodialysis is debatable. Several indexes of thyroid function were assessed in 46 patients undergoing chronic hemodialysis for 2 to 45 months. Low serum levels of thyroxine were found in 69.5% of the patients studied and of triiodothyronine (T3) in 46.5%. Low values of T3-Sephadex binding were noted in 17.3%, of free thyroxine index (FTI) in 26.3% and of radioiodine uptake in 19.3% of the patients; 13.0% had high levels of thyroid-stimulating hormone (TSH). The overall incidence of hypothyroidism, based on FTI and TSH, was 34.8%. We concluded that the diagnosis of hypothyroidism should be based on FTI and TSH levels, and that chronically hemodialyzed patients tend to exhibit biochemical rather than clinical hypothyroidism.

Adolescent↗
PubMed1978

An immunoregulatory factor associated with spleen cells from tumor-bearing animals. I. Effect on tumor growth and antibody production.

An immunopotentiating factor associated with spleen cells of C57BL/6J mice bearing the 3LL tumor is described. Supernatants of cultured spleen cells from tumor-bearing mice (TBM) augmented the generation of both 19S and 7S antibody-producing cells, when injected with sheep erythrocytes into syngeneic C57BL/6J mice. The enhancing supernatant acted both as a polyclonal activator, when injected in the absence of antigen, and as a potentiator of specific antigen-dependent humoral immune responses, when injected in the presence of antigen. It was found to augment induction of specific memory, but not memory expression. Concomitantly with their influence on humoral immune responses, TBM spleen cell supernatants enhanced tumor growth when injected, mixed with 3LL tumor cells, into syngeneic recipients. The secretion of a factor which augments antibody production was not confined to the 3LL tumor system. Spleen supernatants of C47BL mice carrying the B16 melanoma and those of C3H mice carrying the KHT sarcoma had a similar effect on antibody production. These findings suggest that an immunoregulatory factor(s) appears in spleen cells of TBM as a result of their interaction with the neoplastic tissue. This factor can potentiate production of antibodies, possibly also against tumor-associated antigens. The relevance of the immunopotentiating effects of such factor(s) to tumor growth is discussed.

Animals↗
PubMed1978

Glutamine and glutamic acid uptake by rat renal brushborder membrane vesicles.

Glutamine uptake by rat renal brushborder vesicles occurred via two distinct saturable processes with Km values of 0.145 and 8.5 mM which were stimulated by both ionic and sodium gradients with a pH optimum of 6.8--7.1. Glutamic acid uptake also occurred by a two-component system with Km values of 0.016 and 3.60 mM. Both components were stimulated specifically by a sodium gradient. The low Km system for glutamic acid had a pH optimum of 7.2--7.4. Glutamine entry at 0.06 mM was inhibited by a variety of amino acids at 3 mM, including dibasic amino acids, glycine, valine, and phenylalanine. Glutamic acid entry at 0.06 mM was inhibited 20--30% by 3 mM phenylalanine, valine, alpha-aminoisobutyric acid, and glutamine. No metabolic alteration of glutamic acid was observed on incubation with membrane vesicles, but glutamine was significantly hydrolyzed to glutamic acid upon prolonged incubation. Hydrolysis of glutamine was negligible at 15 sec incubation which was employed for measurement of initial rate of entry. These studies provide support for the existence of an uptake system in the brushborder of the renal proximal tubule cell capable of handling the reabsorption of glutamine normally present in glomerular filtrate.

Amino Acids↗
PubMed1978

The fanconi syndrome in Basenji dogs: a new model for renal transport defects.

The renal defects resulting in a Fanconi syndrome were seen in eight Basenji dogs by measuring renal clearance and in vitro amino acid and sugar uptake and performing histopathologic evaluations. Renal tubular handling of glucose, phosphate, sodium, potassium, uric acid, and amino acids was abnormal, and in vitro uptake of labeled lysine, glycine, and alpha-methyl-D-glucoside by renal cortical slices was impaired. Histopathology was normal except for enlarged nuclei in some renal tubule cells. These Basenji dogs, which may be genetically affected, represent a likely model for idiopathic Fanconi syndrome in humans.

Amino Acids↗
PubMed1978

Specific cytotoxic lymphocytes against syngeneic tumors are generated in culture in the presence of syngeneic, but not xenogeneic, serum.

Experiments were performed to test the effect of xenogeneic (fetal calf) serum (FCS) , as compared to syngeneic mouse serum (SMS) on the generation in culture of specific cytotoxic lymphocytes (CL) against syngeneic tumors. Sensitization in FCS against 3LL tumor cells resulted in CL cross-reacting with B-16 tumor cells and vice versa. Anti-syngeneic fibroblast CL also cross-reacted with 3LL. Such cross-reactivities were shown to be derived from CL directed against FCS determinants. In contrast, sensitization in the presence of SMS resulted in CL directed against tumor-specific antigens. Anti-3LL generated in SMS lysed 3LL targets but not B-16, and anti-B-16 lysed B-16 but not 3LL. The two types of CL had two distinct reactivities in vivo. Anti-3LL CL generated in FCS enhanced tumor growth in vivo, whereas anti-3LL CL generated in SMS had an inhibiting effect on the growth of tumor cells. These results indicate that the application of syngeneic serum during in vitro sensitization against syngeneic tumors may open up new possibilities for the analysis of tumor-specific antigens and for eliciting specific immune reactions against such antigens.

Animals↗
PubMed1978

On the development of glycine transport systems by rat renal cortex.

The initial uptake of glycine by renal cortical slices from newborn Sprague-Dawley and Long-Evans rats is the same as that observed in adult tissues. Both newborn and adult tissue possess similar high and low affinity glycine transport systems which require an examination of velocity measurements over a wide range of concentration (0.02--50.0 mM) for their discernment. Initial rates of glycine uptake by isolated renal tubule fragments from newborn and adults are similar at a physiological substrate concentration but at high glycine levels there appears to be a decrease in velocity of uptake (V) associated with the high Km system in the young. Whatever preparation of renal cortex is studied, there is a consistent finding that immature tissue is able to accumulate much higher intracellular levels of glycine than the adult, a finding consistent with slower efflux from the cell. An interpretation of the etiology of physiologic aminoaciduria in young animals should take this into account.

Aging↗
PubMed1978

Benign course of juvenile laryngeal papillomata.

A 17 month-old child with laryngeal papillomata is presented. The symptoms were stridor and gradually developing dyspnea. He underwent two surgical procedures within 4 months, using microsurgical techniques, and eventually recovered. The etiological factors of this rare entity are discussed. The relatively benign course in our patient is stressed, in view of the usual protracted course which is reflected in the literature.

Fibroma↗
PubMed1978

Narcotic addiction, pregnancy, and the newborn.

Between 1954 and 1973, 101 heroin-addicted mothers gave birth to 149 babies at Vancouver General Hospital. Thirty-seven percent of the infants had low birth weights and two thirds were born preterm. Average birth weight was 2,710 gm as compared with an overall average of 3,420 gm for this hospital. Tobacco and alcohol abuse, and poor maternal nutrition probably contributed to the growth retardation. Withdrawal symptoms were observed in 68% of the babies, and this may have been aggravated by multiple drug use, which was prevalent, including alcohol, barbiturates, and "soft drugs." Neonatal mortality rate of 6.7% and a stillbirth rate of 4% resulted in a perinatal mortality rate of 10.7%. Prematurity, respiratory distress syndrome, and other perinatal complications related to an unfavorable social background accounted for most neonatal deaths, but none was attributable directly to narcotic withdrawal.

Adult↗
PubMed1978

Sequential interaction of macrophages, initiator T lymphocytes and recruited T lymphocytes in a cell-mediated immune response to soluble antigen.

We have investigated the sequential interaction of macrophages, initiator T lymphocytes (ITL) and recruited T lymphocytes (RTL) in the development of a T cell-mediated response to soluble antigens. Macrophages were pulsed with soluble antigens and used to sensitize ITL in vitro. The ITL were irradiated to prevent their proliferation and then injected into the footpads of syngeneic mice. Sensitized ITL were found to recruit immunospecific RTL in the draining lymph nodes, as determined by a thymidine uptake assay of the lymph node cells in vitro. The richest source of lymphocytes with ITL activity was the thymus, and progressively less activity was detectable among spleen or lymph node lymphocytes. The magnitude of the subsequent RTL response could be modified by genetic differences between the ITL and the antigen-pulsed macrophages that were used to sensitize them. Thus, ITL conveyed an immunogenic signal to RTL whose magnitude reflected the genotype of the macrophages, but whose specificity was directed by determinants of the soluble antigen.

Animals↗