Effect of periodate oxidation of glycoconjugates of lymphocyte membranes on the immune response in vitro]

Mouse spleen cells treated with sodium periodate for 10 min. at 4 degrees C are stimulated to undergo blastogenesis and to incorporate thymidine. The effect of such treatment on the antibody response in vitro induced by Sheep red blood cells has been evaluated. Periodate-induced proliferation is accompanied by a marked inhibition of the immune response to this antigen. At concentrations leading to mitogenesis, no cytotoxic effect of periodate was observed and treated cells survived well on tissue culture. Cell recoveries from samples treated with periodate at the optimal mitogenic dose, were markedly enhanced when harvested at different days after culturing wheras lower antibody forming cells numbers wereconsistently observed during the culture period.     

Periodate oxidation of lymphocyte membrane glycoconjugates]

Mouse spleen cells free of erythrocytes were suspended in PBS at a concentration of 2 X 10(7) cells/ml and mixed with an equal volume of sodium periodate in PBS for 10 min. at 4 degrees C to give a final concentration of periodate ranging from 10(-4) M to 5 X 10(-3) M. The cells were then washed and suspended (60 X 10(6) ml) in PBS containing 3H-labelled sodium borohydrate and incubated for 30 min, at 23 degrees C. Following this, the cells were washed and the pellets treated with H2SO4 0.1 N for 60 min. at 80 degrees C. Compounds liberated by such treatment, were identified by chromatography as derivates of sialic acid. The data provide direct evidence that the mitogenic effect of sodium periodate is associated to the oxidation of the sialic acid residues on the lymphocyte membrane.     

PPD-induced blastogenesis is auto-regulated by suppressor cells generated in vitro.

Suppressor cell induction can be demonstrated during antigen specific blastogenesis by using the same methods which have shown induction of suppressor cells by Con A. Since suppressor cells are rapidly generated during antigen specific blastogenesis, they must regulate the final level of blastogenesis induced during the seven day in vitro incubation.     

PPD-induced blastogenesis is auto-regulated by suppressor cells generated in vitro

Summary Suppressor cell induction can be demonstrated during antigen specific blastogenesis by using the same methods which have shown induction of suppressor cells by Con A. Since suppressor cells are rapidly generated during antigen specific blastogenesis, they must regulate the final level of blastogenesis induced during the seven day in vitro incubation.Supported by Unites States Public Health Service grants AM-13377 and CA-19266.     

Effect of a mitogenic concentration on membrane glycoconjugates of human lymphocytes

Periodate oxidation of human peripheral blood lymphocytes followed by reduction with 3H labelled sodium borohydride and acidic hydrolysis generates N-AN 7, glycerol and propane 1-2 diol. This indicates that sialyl, fucosyl and probably galactosyl residues are oxidized by periodate. Neuraminidase-treated lymphocytes exhibit decreased N-AN 7 levels, increased N-AN 8 levels and increased glycerol levels. Such results were neither found with mouse splenocytes nor with calf lymph node cells.     

The in vitro effect of aprotinin upon spleen cells from normal and tumour-bearing mice exposed to PPD and tumour cells

Aprotinin (Trasylol) is shown to enhance the response of spleen cells from normal and tumour bearing mice to PPD nd tumour cells. This enhancement is greater in the tumour-bearing mice.     

Suppression of PHA-induced lymphocyte blastogenesis by concomitant presence of PPD in the culture

Summary PHA-induced lymphocyte blastogenic response was remarkably suppressed by the simultaneous presence of PPD in cultures of lymphocytes derived from individuals sensitized to PPD, but not affected by the presence of PPD when the cultures contained lymphocytes from an individual not sensitized to the protein. This double stimulation blastogenesis study with PHA and a specific antigen is feasible as a simple and rapid test to measure cell-mediated immunity to the antigen.Supported by United States grant USPHS Grant AM 27384.     

The in vitro effect of aprotinin upon spleen cells from normal and tumour-bearing mice exposed to PPD and tumour cells

Summary A protinin (Trasylol) is shown to enhance the response of spleen cells from normal and tumour bearing mice to PPD and tumour cells. This enhancement is greater in the tumour-bearing mice.Acknowledgments. We are grateful to Bayer (U.K.) Limited for generous supplies of aprotinin. The PPD was supplied by the Ministry of Agriculture. The work was supported by a grant from the North of England Cancer Research Campaign.     

Bilateral resection of superficial rat kidney cortex: effect on sodium balance.

Bilateral resection of the whole superficial kidney cortex (approximately 75% of glomeruli) was carried out in rats. These animals needed some 2 days longer to restore their sodium balance when placed from low to high sodium intake in comparison with rats subjected to other types of partial nephrectomy.     

Effect of prolactin on human red cell sodium transport

Incubation of red cells with higher concentrations of prolactin in vitro enhanced the cellular sodium level and produced a significant reduction in erythrocyte membrane adenosine triphosphatase activity. This effect was dose and time-dependent. It is the result of an inhibition of the active sodium pump similar to that produced by ouabain, suggesting altered red cell function and electrolyte balance in hyperprolactinemic states.     

Surface morphology of the subfornical organ: effects of low and high sodium chloride diet

Ependymal cells found in the subfornical organ of the rat were counted. Cells covered by small microvilli, small protrusions and smooth cells were frequently found. Also present were cells with long or short cilia, cels with large protrusions and supraependymal cells. High and low sodium diets reduced the number of cells with large protrusions. Microvilli-covered cells increased after a low sodium diet.     

Combined effect of veratridine and sodium aspartate on the rabbit retinas in vitro

Summary Combined effect of veratridine and sodium aspartate on rabbit retinas in vitro was studied. Observations suggested that mode of action of veratridine on the PII and PIII components of ERGs was modified by the presence of sodium aspartate in perfusate.     

The effect of hexamethonium on the secretion induced by sodium deoxycholate in the rat jejunum

Summary The i.v. administration of hexamethonium reduces or abolishes net water secretion induced by sodium deoxycholate in the denervated rat jejunum. The findings suggest that a local nervous reflex may be involved in bile salt-induced intestinal secretion.This research was sponsored by grants from the Swedish Medical Research Council (14X-2855), from the Swedish Society for Medical Sciences, from Magnus Bergvalls Stiftelse and from the Medical Faculty, University of Göteborg.     

Surface morphology of the subfornical organ: Effects of low and high sodium chloride diet

Summary Ependymal cells found in the subfornical organ of the rat were counted. Cells covered by small microvilli, small protrusions and smooth cells were frequently found. Also present were cells with long or short cilia, cels with large protrusions and supraependymal cells. High and low sodium diets reduced the number of cells with large protrusions. Microvilli-covered cells increased after a low sodium diet.Acknowledgments. We thank Dr A. C. Taquini for his helpful discussions and Servicio de Microscopía Electrónica de Barrido, Conicet, and Facultad de Odontologia for technical assistance.     

Voltage-gated sodium channel-associated proteins and alternative mechanisms of inactivation and block

Voltage-gated sodium channels mediate inward current of action potentials upon membrane depolarization of excitable cells. The initial transient sodium current is restricted to milliseconds through three distinct channel-inactivating and blocking mechanisms. All pore-forming alpha subunits of sodium channels possess structural elements mediating fast inactivation upon depolarization and recovery within milliseconds upon membrane repolarization. Accessory subunits modulate fast inactivation dynamics, but these proteins can also limit current by contributing distinct inactivation and blocking particles. A-type isoforms of fibroblast growth factor homologous factors (FHFs) bear a particle that induces long-term channel inactivation, while sodium channel subunit Navβ4 employs a blocking particle that rapidly dissociates upon membrane repolarization to generate resurgent current. Despite their different physiological functions, the FHF and Navβ4 particles have similarity in amino acid composition and mechanisms for docking within sodium channels. The three competing channel-inactivating and blocking processes functionally interact to regulate a neuron’s intrinsic excitability.     

Role of extracellular matrix molecules in the development of the sodium current in quail mesencephalic neural crest cells

The occurrence of the voltage-dependent sodium current has been studied in developing neurons from quail mesencephalic neural crest on different substrates, using the whole-cell patch clamp technique. Explants from 9–12 somite embryos were cultured on dishes coated with type I collagen, fibronectin, laminin or on plastic dishes in a chemically defined medium. After 18 h of culture the sodium current was observed in 70% of the neurons tested, and at 24 h some of these neurons were able to generate an action potential. After 18–25 h cells grown on fibronectinor collagen I-coated dishes showed a significantly higher occurrence of the sodium current (83% and 84% respectively) as compared to cells grown on uncoated plastic dishes (51%). Moreover, in the presence of fibronectin, the current density of the sodium current was more than doubled in comparison with cells grown on other substrates.     

The inhibitory effect of sodium on the contraction of frog's heart perfused with sucrose solution

Résumé Le cur de grenouille continue à battre de lui-même et répond à une stimulation électrique durant 5–6 h s'il reçoit une injection contenant une demi solution isotonique de saccharose, de pyrophosphate de sodium et d'adénosinetriphosphate ou de citrate de sodium. Le chloride de sodium annule ces deux réactions.     

Local adjuvants: the influence of sodium dodecylbenzene sulphonate on immunization with aerosolized antigen.

Guinea-pig respiratory and serum antibody responses were enhanced following exposure to aerosols of bovine IgG2 dissolved in solutions of sodium dodecylbenzene sulphate (SDBS). Enhanced response was seen in both primary and secondary immunization. Cell-mediated immune response (indirect macrophage migration influencing test) was not altered by SDBS. Results are discussed with a view to the possible utility of SDBS as adjuvant for prophylactic immunization.     

Effect of sodium butyrate on the interferon sensitivity of normal or cells transformed by murine sarcoma virus]

Sodium butyrate enhances the sensitivity of MSV transformed murine cells to interferon, but does not influence the response of normal cells. Sodium butyrate might act in transformed cells by restoring the different elements of the cytoskeletal system.     

Unmasking of the fast sodium channel in less than 4 day old embryonic chicken heart by inhibitors of sodium inactivation]

Embryonic Chick hearts aged less than 4 days are not always sensitive to tetrodotoxin, an inhibitor of fast sodium channel. It is shown that in the most frequent cases, in which tetrodotoxin sensitivity is apparently absent, this sensitivity can be demonstrated after previous treatment by veratridine or by toxin II of androctonus australis Hector Scorpion venom. It is concluded that the fast tetrodotoxin-sensitive sodium channel is regularly present in the heart of Chick embryos aged 2 and 3 days, but most often in a permanently inactivated state.