摘要:

SummaryAn explanation has been sought for the mechanism whereby prior irradiation of rats tolerant of sheep erythrocytes facilitates haemolysin formation by transfused normal lymphocytes. Taking account of the effects of depleting tolerant rats of lymphocytes by means of prolonged thoracic duct drainage, it was concluded that enhanced colonization of host lymphoid tissues by transfused cells was unlikely to be the major factor in this facilitation. The formation of haemolysin was investigated in tolerant rats after sub lethal irradiation and the transfer of lymphocytes from normal donors. The haemolysin response after the transfer of thoracic duct lymphocytes to irradiated, tolerant hosts was much weaker than that observed after their transfer to irradiated normal (non‐tolerant) hosts unless the lymphocytes had been incubatedin vitrowith antigen primed peritoneal cells. Previous incubation of the lymphocytes to be injected with unprimed peritoneal cells or with antigen alone failed to enhance the subsequent immune response. Lymphocytes and primed peritoneal cells which had not been incubated together were a much less efficient inoculums than incubated cell mixtures. It is suggested that, in addition to the specific deficiency of its lymphocytes, there is some factor in the tolerant rat inimical to the initiation of an immune response in transfused normal lymphocytes.

ISSN:0004-945X    

DOI:10.1038/icb.1970.38

出版商:Nature Publishing Group    

年代:1970

数据来源: WILEY

摘要:

SummaryThe persistence of cells with the capacity to differentiate for haemolysin formation has been examined in erythrocyte‐tolerant rats transfused with lymphocytes from normal rats. Following the transfer of untreated thoracic duct lymphocytes, plaque‐forming ceil precursors could be recovered from the host's spleen during the first three days, although plaque‐forming cells themselves failed to appear at any time. It is suggested that the sudden disappearance of antibody‐forming cell precursors reflects the induction of immunological tolerance in the transfused lymphocytes or their progeny.When lymphocytes which have been antigenically stimulatedin vitroare transferred to tolerant hosts, large numbers of antibody‐forming cell precursors can be recovered from the host spleens during the third week after transfer. This implies that, if the disappearance of precursor cells from transferred populations of unstimulated lymphocytes represents the induction of tolerance, this state is less readily induced in antigenically stimulated cells.

ISSN:0004-945X    

DOI:10.1038/icb.1970.39

出版商:Nature Publishing Group    

年代:1970

数据来源: WILEY

摘要:

SummaryChanges in wet and dry weight of the heart were investigated in female rats after ovariectomy anti following the administration of oestrogen, progestogen and a combination of oestrogen and progestogen. These changes were related to body weight and the size of the extracellular fluid space of the myocardium.Heart dry weight and body weight in the animals given combined oestrogen and progestogen were maintained closer to those of the controls than in the animals given either hormone separately. Ovariectomy resulted in an increase in body weight and a relative decrease in wet and dry weight of the heart.The extracellular fluid space was increased in the hearts of animals treated with a combination of oestrogen and progestogen, whereas it was not altered in ovariectomized animals or in those given either hormone separately.

ISSN:0004-945X    

DOI:10.1038/icb.1970.40

出版商:Nature Publishing Group    

年代:1970

数据来源: WILEY

摘要:

SummaryRat albumin, transferrin and IgG‐globulin labelled with radioactive iodine were injected intravenously into male rats, and the changes in plasma protein‐bound radioactivity were measured both before and after bilateral nephrectomy or laparotomy performed 96 hours after the injections. The rates of catabolism of all three proteins as assessed from the fall in plasma concentration of labelled protein decreased to a similar degree after both types of operation. Because of the changes in plasma concentration and pool sizes of the proteins after the operations, it was not possible to accurately measure the effect of nephrectomy on catabolism. However, the similarity of results with the two types of operations indicated that the kidney played no more than a relatively small part in catabolism of the proteins.

ISSN:0004-945X    

DOI:10.1038/icb.1970.41

出版商:Nature Publishing Group    

年代:1970

数据来源: WILEY

摘要:

SummaryIodinated vancomycin, when incubated at growth‐inhibitory concentrations with a calture ofMicrococcus lysodeikticus, was absorbed by the growing cells. On fractionation of those cells into tell wall, cell membrane and cytoplasmic fractions, the antibiotic was found to be associated mainly with the first two fractions. The antibiotic initially attached to the cell wall appeared to become associated with the cell membrane on further incubation. At the same time, an increase in the hexosamine content of the cell membrane was observed. In growingM. lysodeikticuscells under progressive inhibition by iodovancomycin, the antibiotic is found at different sites within the cell.

ISSN:0004-945X    

DOI:10.1038/icb.1970.42

出版商:Nature Publishing Group    

年代:1970

数据来源: WILEY

摘要:

SummaryEstimations of extracellular fluid volumes were made before and after three levels of acute haemorrhage in anaesthetised, splenectomised dogs. Three different radioactive isotopes.35SO4,125I and24Na were used.The reduction in sulphate space after 10% and 27% blood loss was replenished in less than 2 hours. However, after 46% blood loss, the sulphate space was markedly reduced and showed no evidence of recovery. The rate loss of the isotope after “equilibration” declined from 12·7% to 9% per hour. When125I or24Na were used the results were different. These isotope dilution spaces 2 hours after haemorrhage were reduced only by an amount equal to the volume of plasma water removed by the haemorrhage.Delay in equilibration of all three isotopes occurred after haemorrhage, and possible explanations for the anomalous behaviour of sulphate after 46% haemorrhage are discussed. From this it is concluded that immediately after severe haemorrhage an accurate assessment of extracellular fluid partitioning may not be possible without a marker which is instantly distributed into the total extracellular fluid space.

ISSN:0004-945X    

DOI:10.1038/icb.1970.43

出版商:Nature Publishing Group    

年代:1970

数据来源: WILEY

摘要:

SummaryAnti‐Vi antibodies present in the serum of mice shortly after immunization have been shown to provide adherence of antigen to the surface of macrophages. In the present study the physicochemical properties of these antibodies were investigated.DEAE‐Cellulose column chromatography and sucrose gradient ultracentrifugation have revealed that all this activity is confined to the IgM fraction of serum. These findings are consistent with the observation that treatment of early anti‐Vi sera with cysteine or 2‐mercuptoethanol completely destroys their agglutinating and adherence‐promoting activities.In addition, it has been found that antibodies which promotein vitrophagocytosis of antigen by macrophages belong to the IgG class of immunoglobulins. The possible implications of these findings are discussed in detail.

ISSN:0004-945X    

DOI:10.1038/icb.1970.44

出版商:Nature Publishing Group    

年代:1970

数据来源: WILEY

摘要:

SummaryThe effect of acetylcholine stimulation on Ca movements in depolarized smooth muscle from toad stomach muscle was investigated.No difference in the content of Ca45due to ACh stimulation could be detected in muscle containing its full complement of Ca. However, in Ca depleted muscle exposed to Ca 0·05 mM, solution, uptake of Ca was accelerated and the equilibrium content of total and exchangeable Ca was increased by some 5% of the total tissue Ca. This amount was similar to the extra Ca lost when muscle was depleted into Ca‐free solution with intermittent ACh stimulation.The efflux of Ca45from normal and replcted muscle was studied, using a constant flow system. ACh stimulation of both normal and repleted muscle resulted in a transient increase in the efflux of Ca45. The slow component of the efflux curve occupied a larger proportion of the cellular Ca in the repleted than in the normal muscle. The increment of Ca uptake due to ACh stimulation during repletion was found to be wholly in this fraction.The significance of these results in relation to an excitation‐contraction‐coupling fraction are discussed.

ISSN:0004-945X    

DOI:10.1038/icb.1970.45

出版商:Nature Publishing Group    

年代:1970

数据来源: WILEY

摘要:

SummaryThe initiation and development of infection in the visceral organs and the central nervous system of mice after intravenous injection of the WE3strain of lymphoctytic choriomeningitis virus has been studied by the immunofluorescence technique and correlated with histological changes.In the liver, virus was taken up within a few minutes by Kupffer cells. Viral replication first occurred within these cells and infection spread from them to hepatic cells. Infiltration of the tissues by mononuclear cells, necrotic changes and signs of sickness all developed at about the same time. Necrosis occurred in foci of infected cells and immunoglobulin was present in and around the lesions.In the central nervous system, lymphocytic choriomeningitis virus infected the walls of blood vessels and passed through the meringue vessels into the surrounding tissue and into the cerebrospinal fluid. Spread of infection from the choroids plexuses occurred at a later stage, but infection was not transmitted from cerebral blood vessels to cells in the brain substance.In infant mice inoculated extraneurally with lymphocytes the choriomeningitis virus, invasion of the central nervous system occurred much earlier and more readily than in adult mice and there was widespread infection of the brain substance as well as the meanings.

ISSN:0004-945X    

DOI:10.1038/icb.1970.46

出版商:Nature Publishing Group    

年代:1970

数据来源: WILEY