摘要:

SummaryTwo established techniques for analysis of plasma membranes, namely. Iactoperoxidase catalyzed surface radioiodination of intact cells and bulk membrane isolation following disruption of cells by shear forces, were applied in studies of membrane proteins of continuously cultured cells of the monoclonal T lymphoma line WEHI‐22. It was found that macromolecular125I‐iodide incorporated into plasma membrane proteins of intact cells was at least as good a marker for the plasma as was the commonly used enzyme 5′‐nucleotidase. T lymphoma plasma membrane proteins were complex when analysed by polyacrylamide gel electrophoresis in sodium dodecylsulphate‐cotaining buffers and more than thirty distinct components were resolved. More than fifteen of the components observed on a mass basis were also labelled with125I‐iodide. Certain bands, however, exhibited a degree of label disproportionate to their staining properties with Coomassie Blue. This was interpreted in terms of their accessibility to the solvent in the intact cells.

ISSN:0004-945X    

DOI:10.1038/icb.1976.31

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY

摘要:

SummaryExtracts of nematodes have been used as skin test antigens in the diagnosis of nematode infections for many years.Ascaris lumbricoidesandTaxocara canisare two nematodes commonly involved in human parasitism, the latter being associated with the clinical condition of Visceral Larva Migrans.In vitroandin vivoexperiments reported in this paper confirm experimentally, as well as clinically, the existence of cross‐reacting antigens betweenT. canisand Ascaris spp., and probably betweenT. canisand other nematodes. These cross‐reactions compromise the usefulness of skin tests in the diagnosis of such parasitic infections.

ISSN:0004-945X    

DOI:10.1038/icb.1976.32

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY

摘要:

SummaryCutaneous hypersensitivity reactions were elicited in guinea‐pigs infected with the parasitic nematodeTrichastrongylus colubriformisby injecting them with a nude extract ofT.colubriformisfourth‐stage larvae. The reaction was characterized by early oedema and pronounced cellular infiltration, initially with neutrophils hut later with mononuclear cells, basophils and variable numbers of eosinophils. Because basophils have been implicated as effector cells in the protective immune response of guinea‐pigs to this nematode, the capacity to elicit a basophil‐rich cellular infiltrate in infected animals might be a useful assay forT. colubriformisprotective antigen(s).

ISSN:0004-945X    

DOI:10.1038/icb.1976.33

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY

摘要:

SummaryThe experiment comprised two sections. First, radiotracer techniques were used to study the metabolism of IgG1and IgG2in 5 non‐pregnant and 4 pregnant ewes. In the pregnant ewes, the rates of synthesis for IgG1and IgG2were similar to the rates observed in non‐pregnant animals. However, the irreversible loss of IgG1was significantly greater than IgG2in pregnant ewes and IgG1in non‐pregnant ewes. Additionally, it was found that most of the IgG1and virtually all of the IgG2in mammary secretion was serum derived.Secondly, the levels of sodium, potassium and lactose and the selective index for IgG1in mammary secretions of 5 pregnant ewes were monitored over the parturient period. The values of all the measures remained relatively constant until one day before parturition. From one claypre‐partum, the levels of potassium and lactose in mammary secretion began to increase and had risen 2‐3 fold by 5 dayspost‐partum.Over the same period, the selective index for IgG1decreased 20 fold, whereas the level of sodium fell from approximately 32 mmol/l to 18 mmol/l. The concentration of IgG1in plasma slowly declined from approximately 23 g/l to 15 g/l over the last 10 days of pregnancy.During the parturient period, the decline in plasma IgG1levels, in comparison with IgG2, without alteration in the rates of synthesis of either immunoglobulin, supports the hypothesis that selective transport of IgG1into mammary secretion occurs without degradation. The results also indicate that the transport of sodium and potassium into mammary secretions are altered over the parturient period.

ISSN:0004-945X    

DOI:10.1038/icb.1976.34

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY

摘要:

SummaryTarget cells (P‐815 mastocytoma cells) infected with ectromelia virus became susceptible to lysis by H‐2 compatible specific effector T cells within one hour of exposure of the cells to virus. This is long before viral progeny are produced and shed from the cell.Polyacrylamide gel electrophoresis (PAGE) profiles of the plasma membranes from infected and uninfected P‐815 cells pulsed with35S‐methionine for one or a few hours after infection with virus were very complex and showed no consistent differences. P‐815 cells, infected with ectromelia virus in the presence of an inhibitor of protein synthesis, pactamycin. slowly became susceptible to cell mediated lysis when the pactamycin was removed. The number of polypeptide species synthesized under these conditions was reduced to only three, of molecular weights between 10,000–50,000 daltons.Specific, newly synthesized membrane components recognized by mouse convalescent sera were isolated by immune complexion and examined by PAGE. Six polypeptide bands were seen, the major one correlating with one observed in the pactamycin experiment. The results suggested that the convalescent serum recognized both viral and host cell coded antigens. The significance of these findings is discussed.

ISSN:0004-945X    

DOI:10.1038/icb.1976.35

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY

摘要:

SummaryPeritoneal exudate cells from mice infected with ectromelia virus were cytotoxic for virus‐infected target cells as measured in a51Cr release assay. Cytotoxic activity seemed to be T cell‐dependent as it was largely abolished by treatment with anti‐θ serum and complement but was not impaired by macrophage depletion. The kinetics of development of cytotoxicity in the peritoneal cavity lagged behind spleen cytotoxicity by 1–2 days. Peak activity in peritoneal cells was present about 6 days after intravenous infection with virus. These studies suggest that macrophages present in the free peritoneal cell populations of ectromelia‐infected mice are not cytotoxic for virus‐infected target cells. The effect of macrophages in virus clearance is therefore likely to be due to phagocytic rather than cytotoxic effects.

ISSN:0004-945X    

DOI:10.1038/icb.1976.36

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY

摘要:

SummaryThe responses of popliteal lymph nodes of sheep to Ross River virus (RRV) or Kunjin virus (KV) have been studied by monitoring the cell populations, virus titre. antibody titre and plaque‐forming cell (PFC) content of the efferent lymph. In a typical primary response to subcutaneous inoculation in the lower hint! limb of either RRV or KV, the flow rate of lymph increased slightly. Increased cell concentrations in the lymph following inoculation caused the hourly cell outputs to rise 5·3‐ to 10·1‐fold above pre‐challenge levels. High cell outputs were sustained at greater than 3‐fold above pre‐challenge figures for up to 10 days. The increased number of large, blastic lymphocytes ranged from 4·0‐ to 14·9‐fold; the increase in these cells usually followed the rise in total number of lymphocytes by 24 to 48 h and remained at greater than 3‐fold higher levels for up to 12 days.Ross River virus was recovered in the efferent lymph for at least 36 h after inoculation. Sudden disappearance of the virus from the lymph was correlated with the onset of significant haemagglutination‐inhibition antibody titres by 3 to 4 days after infection. In the efferent lymph, PFC were detected 5 to 7 days after primary or secondary inoculation of KV or RRV when lymphocytes were incubated with specific haemaggluttnin‐coated goose erythrocytes and guinea‐pig complement. Antibody levels in the lymph were persistent while the occurrence of PFC was transient.

ISSN:0004-945X    

DOI:10.1038/icb.1976.37

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY

摘要:

SummaryPlasminogen and a spectrum of fibrinogen‐like proteins are found in a saline eluate of sucrose washed bovine erythrocytes. It seems probable that these proteins are membrane boundin vivo, and, as such, their physiological significance is discussed.

ISSN:0004-945X    

DOI:10.1038/icb.1976.38

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY

摘要:

SummaryThe unconjugated bile salt, sodium deoxycholate, at a concentration of 0·5 mM was shown to inhibit the intestinal uptake of the amino acids L‐glycine, L‐leucine, L‐proline, L‐lysine and L‐tyrosine in ratsin vitro. This effect was acutely reversible except for tile basic amino arid L‐lysine and is therefore not simply due to tissue damage. These results, and the recent finding that sodium deoxycholate inhibits intestinal absorption of amino acidsin vivo, suggest that impaired intestinal amino acid transport may contribute to hypo‐proteinaemia in patients with bacterial overgrowth in the upper small intestine in whom deoxycholate is present in the small intestinal lumen in excessive concentrations.

ISSN:0004-945X    

DOI:10.1038/icb.1976.39

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY

摘要:

SummaryIsolated perfused segments of the ventral rat tail artery have been used in this study to investigate the effects of octapressin on vascular smooth muscle and its interaction with other vasoconstrictor agents. It was found that repeated octapressin administration was associated with tachyphylaxis and that the onset and rate of development of this phenomenon could he modified by cocaine. The constrictor action of catecholamines, electrical stimulation and serotonin on the rat tail artery as potentiated by octapressin. Mechanisms which may be involved in octapressin tachyphylaxis are discussed.

ISSN:0004-945X    

DOI:10.1038/icb.1976.40

出版商:Nature Publishing Group    

年代:1976

数据来源: WILEY