摘要:

Summary3H‐thymidine and3H‐cytidine have been used to study the histological localization of DNA‐ and RNA‐synthesizing cells in popliteal lymph nodes from untreated, immunized and neonatally thymectomized rats. Active cell proliferation, as measured by3H‐thymidine incorporation, was demonstrated in the medulla of unstimulated nodes from normal and from neonatally thymectomized rats. After an immunological stimulus, an early increase in medullary cell proliferation was associated with a similar but less intense reaction in the cortex. A partial dissociation between the sites of cell proliferation and the sites of most active RNA synthesis was noted. Cells with the highest apparent RNA‐synthetic rates were found predominantly in the cortex. Reticular cells, histiocytes, and plasma cells were found to retain labelled RNA longer than the other cells of the lymph nodes.The ability to achieve considerably more intense labelling in popliteal lymph node cells than in the rest of the lymphoid system by hind foot‐pad injections of3H‐nucleosides was confirmed. However, attempts to use this finding for a study of lymph node cell migration were complicated by a failure to obtain adequate numbers of labelled cells after injection of3H‐thymidine, and by the difficulty of finding a dose of3H‐cytidine which labelled small lymphocytes in the popliteal nodes but not blast cells in other organs. It was possible, however, to demonstrate lymphocyte migration within 30 minutes of selective labelling of one popliteal node. Small numbers of migrant cells were found in other lymph nodes, spleen, thymus, and ileal submucosa.

ISSN:0004-945X    

DOI:10.1038/icb.1965.9

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY

摘要:

SummaryResults reported in this and the succeeding paper indicate that Brazilian and Californian myoxma viruses, Shope's rabbit fibroma virus, hare fibroma virus, and squirrel fibroma virus form a distinctive subgroup of the poxviruses, which we have designated the myxoma‐fibroma subgroup. Strains of all of these viruses, including three isolates of rabbit fibroma virus from eastern U.S.A. and a large number of isolates of myxoma viruses from California and South America, have been examined for their capacity to produce plaques in monolayers of four types of cell.The myxoma viruses produce plaques in rabbit embryo fibroblasts and in primary and continuous line rabbit kidney cells. Isolates from California produce smaller plaques than those produced by most strains from South America. A plaque type mutant of a virulent Brazilian strain was found to have altered virulence and pathogenicity for laboratory rabbits. All myxoma viruses also produce small clear plaques on chick embryo fibroblasts, if DEAE dextran is included in the overlay medium. Because of the ease of production of the cells this technique is recommended for routine plaque assay of myxoma viruses.Rabbit and squirrel fibroma viruses produce small clear plaques on rabbit embryo fibroblasts and small proliferative foci on rabbit kidney cells, but no plaques on chick embryo fibroblasts. Hare fibroma virus produces a very few, very small plaques on rabbit cells only. All the viruses reactivate heat‐inactivated rabbitpox virus on all types of cells, but with varying efficiencies.Plaque reduction tests and cross‐protection tests in rabbits establish the relationship between the five viruses, but squirrel and hare fibroma viruses produce a relatively low degree of resistance to myxoma virus.

ISSN:0004-945X    

DOI:10.1038/icb.1965.10

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY

摘要:

SummaryThe soluble antigens of several strains of myxoma virus, and of rabbit and hare fibroma viruses, were compared by gel diffusion tests. Potent preparations showed up to six lines when tested against homologous antisera.There were strong cross‐reactions between strains of myxoma virus derived from widely separated parts of North and South America, but three groups of strains could be distinguished on the basis of the gel‐diffusion tests and the symptomatology of the disease produced in European rabbits. These were Brazilian, which included most of the strains from South America; Californian, a homogeneous group of wide temporal and spatial distribution in that State; and some strains from Colombia and Panama which were antigenically like Californian virus but resembled Brazilian virus in other properties.Three strains of rabbit fibroma virus derived from Michigan, Maryland and New Jersey were antigenically indistinguishable. Cross‐reactions between the soluble antigens of hare and squirrel fibroma virus and myxoma virus were very weak. Cross‐reactions of the soluble antigens of rabbit fibroma virus and myxoma virus on the one hand, and rabbit and hare fibroma viruses on the other, were more extensive.Lack of satisfactory preparations of soluble antigens and antisera precluded adequate investigation of the soluble antigens of squirrel fibroma virus. With some preparations of soluble antigens of many poxviruses, of several different subgroups, and with certain antisera, a line was seen which is thought to represent the interaction of the poxvirus group antigen and its antibody.Electron micrographs of thin sections of infected cells showed that hare and squirrel fibroma viruses, which had not previously been examined with the electron microscope, were morphologically typical poxviruses.The myxoma‐fibroma subgroup of the poxviruses and its evolutionary history are briefly discussed.

ISSN:0004-945X    

DOI:10.1038/icb.1965.11

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY

摘要:

SummaryA γ1 macroglobulin with cold haemagglutinating activity of the anti‐I type was localised by the fluorescent antibody technique in the bone marrow plasma cells and their precursors in a patient suffering from lymphoma. No localization occurred in the “naked” lymphocytes whose presence in the marrow gave rise to a diagnosis of lymphoma. The plasma cells containing the macroglobulin appeared to be morphologically identical to those containing normal 7S γ2‐globulin, and in no case was the presence of both proteins observed in the same cell.

ISSN:0004-945X    

DOI:10.1038/icb.1965.12

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY

摘要:

SummaryA technique is described for the detection and enumeration of cells producing antibacterial (“O”) antibody. Erythrocytes sensitised with specific bacterial polysaccharide are used in a modification of Jerne's plaque technique.

ISSN:0004-945X    

DOI:10.1038/icb.1965.13

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1965.14

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1965.15

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY

摘要:

SummaryThe occurrence, in about 17 per cent of rats, of an accessory pancreatic duct opening directly into the duodenum is described and the practical implications of this finding are discussed. The presence of anastomoses between pancreatic ducts is noted.

ISSN:0004-945X    

DOI:10.1038/icb.1965.16

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY

摘要:

SummaryA histidine loading test was performed on 31 patients before and after saturation with folic acid. These results were compared with pre‐treatment serum folate levels. Thirteen patients had normal serum folate levels and urinary histidine metabolite excretion; six patients with low serum folate showed high urinary histidine metabolite excretion which returned to normal after folic acid therapy. Five patients had low serum folate but did not excrete abnormal concentrations of histidine metabolites. Seven patients had normal serum folate but excreted high concentrations of histidine metabolites which were reduced to normal after folic acid therapy.

ISSN:0004-945X    

DOI:10.1038/icb.1965.17

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY

摘要:

SummaryThe kinetics of the initial step of killing of sensitive bacteria by colicin CA42‐E2suggest that only one lethal unit or molecule is required to kill. Using a new sensitive assay it is shown that 30‐90 such lethal units can be adsorbed on one cell. Each lethal unit corresponds to 105Dalton in the purified colicin which is similar to the probable molecular weight. The significance of these findings is discussed.

ISSN:0004-945X    

DOI:10.1038/icb.1965.18

出版商:Nature Publishing Group    

年代:1965

数据来源: WILEY