摘要:

SummaryThe concentration and output of lymphocytes in lymph from the popliteal node in sheep were varied by antigenic stimulation of the lymph node and by intravenous administration of bovine anti‐lynipbocyte serum (ALS). The 4–5‐fold increase in output and concentration of lymphocytes in lymph following antigenic stimulation of the node was accompanied by a 25–35% increase in the concentration of total protein and albumin. The above changes were not observed in afferent lymph draining the site of antigen injection. There was a 75–80% decrease in concentration of lymphocytes in lymph from the unstimulated popliteal lymph node following the administration of ALS and this was accompanied by decreases of 10–35% in the concentration of albumin and immunoglobulin. Essentially the same changes were observed when ALS was administered 6 days after antigenic stimulation of the node.Administration of ALS to sheep with cannulated intestinal lymphatic ducts was followed by a 75–80% reduction in lymphocyte concentration and in decreases ranging from 12–50% in the concentration of albumin, IgM and IgG2.It is suggested that a significant loss of plasma protein is associated with the migration of lymphocytes between the endothelial cells of the post‐capillary venules in lymph nodes.

ISSN:0004-945X    

DOI:10.1038/icb.1975.1

出版商:Nature Publishing Group    

年代:1975

数据来源: WILEY

摘要:

SummaryThe thoracic duct of Wistar strain rats was cannulated during 5 days fur studying the effect of selective lymphocyte depletion on the lymphoid tissue. A technique for the continuous infusion of cell‐free lymph, whole lymph or Eagle's medium to the rat with the thoracic duct fistula is described in detail.The prolonged drainage of lymph from rats was followed by lymphopenia, severe atrophy of lymphoid tissues and the depletion of small lymphocytes in the thymus‐dependent areas of spleen and lymph nodes. The infusion of cell‐free lymph into the drained rat resulted in the recovery of the weight of lymphoid tissues and in the massive proliferation and accumulation of large, cells with prominent nucleoli and intensely pyroninophilic cytoplasm in the lymphocyte depleted areas of the peripheral lymphoid tissues and thymic cortex. There was histological evidence that the large pyroninophilic cells developed well in the spleen and tended to localize preferentially around the periarteriolar region through the marginal zone bridging channels to the red pulp, The infusion of Eagle's medium was found ineffective in restoring the weight of the lymphoid tissues and in bringing about the proliferation of lymphoid cells. The rats infused with whole lymph showed almost similar findings biologically and histologically to those of sham‐operated rats.

ISSN:0004-945X    

DOI:10.1038/icb.1975.2

出版商:Nature Publishing Group    

年代:1975

数据来源: WILEY

摘要:

SummaryAllogeneic reactions have conventionally been considered as typical immune responses by one population of cells to antigens present on the other. This view is inadequate, since it does not explain many features of these reactions, among which are: (1) reactivity is much higher between different strains within a species than between species, in spite of the much greater antigenic disparity in the second case; (2) a very high proportion of cells may respond to allogeneic stimuli; (3) major histocompatibility differences are not essential for vigorous allogeneic reactions; (4) the responding population need not be immunologically competent to respond to antigens of the stimulating population; (5) the stimulating population must be both metabolically active and immunocompetent.We have tried to produce a model of cell interaction which will account for these and other anomalies, while at the same time explaining both normal antigenic stimulation (through cell‐cell cooperation) and allogeneic interactions as examples of the same basic mechanism. The model is based on the Bretscher‐Cohn scheme of cell interaction. An allogeneic reaction is seen as having two stages: (1) Cells come together when antibody receptors on cells of one population combine with antigens on cells of the other. To this extent, our model is the same as the conventional one. It need not be the responding population which has the receptors, however. (2) A species‐specific proliferation signal passes between the cells. This is the same signal as is involved in normal antibody induction. Even antigen‐receptor bonds which are very weak may result in effective stimulation of one or both partners because of enhancing effect of this signal, and because the antigens involved are probably repeated over the cell surface, enabling multipoint binding. This explains the very high proportions of cells which proliferate. The exact outcome of any allogeneic interaction will depend on which of the two populations have antibody receptors for antigens on the other, which can produce the proliferative stimulus, and which can respond to either the proliferative signal alone or to this stimulus plus antigen.

ISSN:0004-945X    

DOI:10.1038/icb.1975.3

出版商:Nature Publishing Group    

年代:1975

数据来源: WILEY

摘要:

SummaryThe effect of corticosteroid‐induced parturition on transfer of immunoglobulin into mammary secretion of cows has been studied. Seven nonlactating cows in late gestation were injected intramuscularly with a long‐acting synthetic glucocorticoid and the concentrations of IgG1, and IgG2, were followed in blood serum and mammary secretion which were collected before and after parturition.Within 1 week of injection the udder became distended with secretion identical in appearance to mature milk. In contrast to the situation in normal cows approaching parturition, both the concentration of IgG1, in secretion and the selective index of IgG1, decreased after the glucocorticoid injection. A feature of the results was the absence in treated cows of the characteristic decrease in serum concentration of IgG1, just before parturition.It is concluded that glucocorticoid treatment of cows in late pregnancy results in a decreased availability of colostral immunoglobulin to the newborn calf.

ISSN:0004-945X    

DOI:10.1038/icb.1975.4

出版商:Nature Publishing Group    

年代:1975

数据来源: WILEY

摘要:

SummaryA series ofin vivoandin vitroinvestigations was performed to examine the localisation of sorbitol pathway activity in the rat renal cortex and to investigate the possible relation that the accumulation of sorbitol pathway intermediates in renal cortical tissue may have to the pathogenesis of renal complications in diabetes mellitus.Neither of the sorbitol pathway intermediates, sorbitol or fructose, were detected either in intact glomeruli which had been isolated from rats rendered chronically diabetic with streptozotocin, or in metabolically active glomeruli which had been incubatedin vitroin high glucose media. Such data agreed with previously published observations that the enzyme aldose reductase is not present in renal glomeruli, and suggested that changes in sorbitol pathway activity cannot be directly related to the pathogenesis of diabetic glomerulosclerosis.Sorbitol was detected in low concentrations (3·1 μmol/g protein) in cortical tubules which had been isolated from the renal cortex of rats rendered chronically diabetic with streptozotocin. This concentration of sorbitol was higher than that in the intact renal cortex of the diabetic animal (0·3 μmol/g protein) or in the cortical tubules of non‐diabetic animals (0·5 μmol/g protein). It is apparent that the renal cortical tubule is a major site of sorbitol pathway activity in the renal cortex. However, there is presently no obvious causal relationship between the accumulation of such relatively low concentrations of sorbitol in the renal cortical tubule and the pathogenesis of glomerulosclerosis or cortical tubular lesions in diabetes.

ISSN:0004-945X    

DOI:10.1038/icb.1975.5

出版商:Nature Publishing Group    

年代:1975

数据来源: WILEY

摘要:

SummaryStudies on the incorporation of DL‐[1‐14C] leucine into myosin, total myofibrillar protein and total sarcoplasmic protein have shown agedependent alterations in the rate of synthesis of these proteins in red and white skeletal muscles of chicks. During the early phase ofex ovodevelopment white muscle synthesizes significantly higher amounts of myofibrillar proteins, especially myosin, in comparison with red muscle. The rate of sarcoplasmic protein synthesis in red and white muscles one day after hatching is almost identical. The red muscle shows a markedly higher rate of sarcoplasmic protein synthesis from 10 days after hatching. The incorporation of amino acid into various protein fractions of both the muscle types decreases with advancing age. In adult chicks red muscle displays a higher ability to synthesize sarcoplasmic and myofibrillar proteins.

ISSN:0004-945X    

DOI:10.1038/icb.1975.6

出版商:Nature Publishing Group    

年代:1975

数据来源: WILEY

摘要:

SummaryExperiments were carried out on foetal lambsin uterofrom 103 to 133 days' gestation, to measure the daily flow and solute composition of liquid from the foetal lung. The mean daily flow from foetuses with a tracheal fistula was 231 ml/day (9·6 ml/h), while the mean hourly flow in foetuses with a tracheal loop was 5·1 ml/h. The pattern of flow of lung liquid was intermittent and irregular, with short periods of rapid flow interspersed with longer periods of slow and no How. The Na+, Ca2+, Mg2+, Cl−and urea concentrations showed no significant change with increasing gestational age, but the K+concentration showed a significant rise. It is concluded that the lung of the foetal lamb behaves as an exocrine gland, secreting a substantial volume of liquid of a relatively constant composition.

ISSN:0004-945X    

DOI:10.1038/icb.1975.7

出版商:Nature Publishing Group    

年代:1975

数据来源: WILEY

摘要:

SummarySheep plasma renin substrate was purified 1,200‐fold by using nephrectomised sheep plasma, followed by DEAE‐Sephadex chromatography and gel filtration. The purified substrate contained 8 μg angiotensin II/mg protein and had an estimated molecular weight of 52,000. The kinetic characteristics of the purified substrate were identical both to those of unpurified nephrectomised sheep plasma and to normal sheep plasma substrates. At pH 7·5, Kmof the human renin‐sheep substrate reaction was 0·29 μM and for sheep renin‐sheep substrate, 2·0 μM. Sheep substrate was susceptible to peptic digestion with generation of pepsitensin.Human renin substrate was less readily purified. DEAE‐Sephadex chromatography of plasma from pregnant women at 36–40 weeks' gestation produced a 70‐fold increase in purity (0·9 μg angiotensin II/mg protein). No further increase was achieved with gel filtration. Human renin substrate behaved as a larger (mol. wt. 82,000) more anionic protein than sheep substrate and was resistant to the proteolytic actions of both pepsin and sheep renin. Kmfor the human renin‐human substrate reaction was high and could not be accurately determined (range 3–8 μM. mean 5·7 μM). The presence of human substrate in a human renin‐sheep substrate system did not alter the measured initial velocity.In both sheep and man, the normal concentration of renin substrate is considerably less than Kmand must therefore be considered a determinant of angiotensin production ratein vivo.

ISSN:0004-945X    

DOI:10.1038/icb.1975.8

出版商:Nature Publishing Group    

年代:1975

数据来源: WILEY

摘要:

SummaryThree dipeptides (L‐alanyl‐L‐alanine, β‐alanyl‐L‐histidine and L‐prolylglycine), representative of distinctly different transport groups, and a dicarboxylic acid dipeptide (L‐glutamyl‐L‐glutamic acid) showed a quantitatively equivalent decrease of absorption (mean difference, 12% disappearance 15 min−15 cm−1) from jejunal loopsin vivoin pyridoxine deficient rats, compared with pyridoxine‐repleted controls. Analysis of results for seven dipeptides, including three studied previously, indicated that pyridoxine deficiency caused a general or non‐specific reduction in dipeptide transport, similar for all dipeptides. Decrease in dipeptide transport in vitamin deficiency ran parallel to, but was significantly less than, the decrease in amino acid transport, suggesting in theory involvement of pyridoxine in a common cellular efflux mechanism or, less likely, in the energetics of active transport.

ISSN:0004-945X    

DOI:10.1038/icb.1975.9

出版商:Nature Publishing Group    

年代:1975

数据来源: WILEY