ISSN:0004-945X    

DOI:10.1038/icb.1985.64

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY

摘要:

SummaryExposure of lymphocytes from F2hybrid and backcross rats of the PVG and DA strains to inter‐parental strain alloantisera and complement frequently and unexpectedly revealed incomplete susceptibility within a population of cells. This heterogeneity did not appear to result from variable susceptibility to cytotoxic mechanisms. A more likely explanation was that variation occurred in the expression of the target determinants within the lymphocyte population. A similar heterogeneity was also demonstrable in populations of lymphocytes from rats of the inbred DA strain, provided appropriate alloantisera were used. Antisera raised in PVG rats against individual (PVG × F1) backcross rats frequently effected intermediate levels of DA cell destruction in the presence of complement, although exposure of DA lymphocytes to PVG anti‐DA serum plus complement resulted in their uniform destruction. The nature of the target antigens that were subject to variable expression was not established, but it seemed likely that they were related to histocompatibility determinants.

ISSN:0004-945X    

DOI:10.1038/icb.1985.65

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY

摘要:

SummaryThe relationship between the graft‐versus‐host reactivity of lymphocytes from F2hybrid and backcross rats and their susceptibility to inter‐parental strain alloantisera has been investigated. Apart from associations between the immunological responsiveness of individual rats and the extent of alloantiserum susceptibility of their lymphocytes, selective reactivity of groups of lymphocytes that were separable from the general population by means of their alloantiserum susceptibility was observed. Those host lymphocytes which expressed a preponderance of DA‐derived determinants were preferentially implicated in graft‐versus‐host reactions elicited by PVG lymphocytes in (PVG × DA)F2hybrid rats. The anti‐(PVG × DA)F1hybrid reactivity of some (PVG × F1) backcross rats was selectively concentrated in that fraction of the lymphocyte population which expressed the highest levels of PVG‐derived determinants. It is proposed that heterogeneously expressed MHS determinants may have a role in regulating selective participation by subpopulations of lymphocytes in allogeneic reactions.

ISSN:0004-945X    

DOI:10.1038/icb.1985.66

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY

摘要:

SummaryBlastocysts of the PVG and DA rat strains were transferred to pseudopregnant females of the opposite strain. Those embryos of which the biological and surrogate mothers were allogeneic with respect to each other exhibited a significantly impaired rate of survival. Lymphocytes from PVG rats born following the transfer of blastocysts to DA surrogates invariably possessed anti‐(PVG × DA)F1hybrid graft‐versus‐host reactivity substantially in excess of that of cells from normal PVG rats.

ISSN:0004-945X    

DOI:10.1038/icb.1985.67

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1985.68

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY

摘要:

SummaryThe effect of two immunosuppressive agents, azathioprine and cyclophosphamide, with and without UVB sunscreen protection on UV‐induced skin carcinogenesis was studied in the albino hairless mouse.In a daily treatment regime spanning 9 weeks, groups of mice were immunosuppressed with either drug, and were exposed to minimally erythemal doses of a light source simulating the UV portion of the solar spectrum. The accumulated UV exposure alone induced skin tumours in 77% of mice. Azathioprine, but not cyclophosphamide, significantly enhanced the incidence of UV tumorigenesis.Photoprotection by topical application of one of two commonly used UVB sunscreens, 2‐ethyl‐hexyl‐p‐methoxycinnamate (2‐EHMC) or octyl‐N‐dimethyl‐p‐aminobenzoate (o‐PABA), reduced the UV tumour incidence to zero in immunologically normal mice and to 8‐15% in immunosuppressed mice.Unexpressed latent tumour initiations were revealed in all sunscreen‐protected groups by the subsequent application of a tumour promoter, croton oil. In immunologically normal mice 2‐EHMC had allowed initiations in 39% of UV‐irradiated mice, and o‐PABA in 16‐5%. However, in UV‐irradiated mice immunosuppressed with azathioprine there had been initiations in 78% of mice protected with 2‐EHMC and 65% of mice protected with o‐PABA. Photoprotected mice immunosuppressed with cyclophosphamide did not show the same increase in UV‐initiations (22% with 2‐EHMC, 23% with o‐PABA).These results provide evidence that azathioprine increases the susceptibility of the skin to UV carcinogenesis. However, UVB sunscreens afford effective protection from overt tumour expression in the absence of a tumour promoter.

ISSN:0004-945X    

DOI:10.1038/icb.1985.69

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY

摘要:

SummaryA convenient procedure is described for the purification of rat trypsin. Tissue was homogenized and extracted at pH 4 and the soluble fraction purified by a two‐step affinity chromatography. After polyacrylamide gel electrophoresis at pH 8×8, the purified enzyme was resolved into 1 major and 2 minor bands all of which possessed trypsin‐like enzyme activity. Antibodies to rat trypsin were raised in rabbits and utilized in establishing a sensitive radioimmunoassay procedure for the enzyme. The assay was adapted to study the levels of the enzyme in the circulation of normal Wistar and spontaneously diabetic Bio Breeding Wistar rats before onset of insulin‐dependent diabetes mellitus in a longitudinal fashion. In the normal rat, serum levels of immunoreactive trypsin were higher in younger animals and showed a decline after weaning. This pattern was also seen in the Bio Breeding Wistar rats. In about half the number of Bio Breeding Wistar ratis, serum immunoreactive trypsin levels were much higher than in normal rats. These results may imply that in some Bio Breeding Wistar rats the disease may be associated with inflammatory lesions of the exocrine pancreas.

ISSN:0004-945X    

DOI:10.1038/icb.1985.70

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY

摘要:

SummaryRat liver microsomes can be prepared by the addition of glutathione to post‐mitochondrial supernatant (PMS) and its subsequent sedimentation at 10,000g. These microsomes seem to be unaffected with respect to their major components, and substantial loss of their ribosomes on treatments with various degranulating reagents shows that they contain intact ribosomes. The indices of ribosomal attachment show that these preparations contain more ribosomes per unit area of membrane surface as compared to those prepared at highgforces. High values of per cent degranulation by incubating these microsomes with coded carcinogens and failure of non‐carcinogens to cause this effect show that the technique can be used efficiently for quick, inexpensive and more accurate prediction of carcinogens in human environments.

ISSN:0004-945X    

DOI:10.1038/icb.1985.71

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY

摘要:

SummaryOxytocin‐containing neurons and axon terminals contacting the neurons of the rat paraventricular nucleus were investigated by the peroxidase‐antiperoxidase technique for light and electron microscopy. At the light microscopic level the reaction product was seen to fill the somata, dendrites and axons of the neurons. At the ultrastructural level the immunoprecipitate was localized on cytoplasm (including ergastoplasm) and neurosecretory granules (NSG) of the somata; microtubules, ergastoplasm and NSG of the dendrites; and NSG of the axons. Axon terminals synapsing on the surface of the labelled somata and dendrites were exclusively unlabelled. The somata and dendrites were observed to receive both asymmetrical (Gray's type I) and symmetrical (Gray's type II) synapses with clear, mostly spherical and flattened vesicles, respectively. Frequently, pleomorphic vesicles and a few dense‐core vesicles occurred in both types of synapses. There also were present some unlabelled bridge‐like axon terminals making ‘double’ synapses either on two labelled dendritic processes or on one unlabelled and one labelled dendrite. The present findings demonstrate that the somata and dendrites of the oxytocin‐containing neurons receive diverse innervation. At the same time there was no evidence in this study for synaptic input to the labelled axons of the neurons.

ISSN:0004-945X    

DOI:10.1038/icb.1985.72

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY

摘要:

SummaryTwo lectins were detected in haemolymph from the oysterPinctada maxima, a macromolecular (approximately 8 × 106dalton) N‐acetyl‐galactosamine‐binding lectin and a lower molecular weight (approximately 4 × 105dalton)α‐galactose‐binding lectin. The macro‐molecular lectin agglutinated human type A erythrocytes to a greater extent than human type B or O erythrocytes and was the major lectin detected in the haemolymph. The 4 × 105dalton lectin agglutinated human type A, B and O erythrocytes to the same extent.

ISSN:0004-945X    

DOI:10.1038/icb.1985.73

出版商:Nature Publishing Group    

年代:1985

数据来源: WILEY