摘要:

SummaryTo study the effects of certain vasodilator drugs on the coronary vasculature of the transplanted heart, dog hearts were Implanted into the necks of recipient dogs and connected to the circulation so that coronary blood flow and coronary vascular resistance could be measured continuously. During the first six hours close arterial injections of adenosine and dipyridamole produced marked increases in coronary blood flow and reduced coronary vascular resistance in the transplanted heart; dipyridamole greatly potentiated the vasodilator actions of adenosine. Propranolol, in a beta adrenergic blocking dose, did not alter coronary blood flow or coronary vascular resistance or influence the actions of dipyridamole or adenosine. Low dose infusions of aminophylline uniformly reduced coronary blood flow and increased coronary vascular resistance and also blocked the actions of dipyridamole and adenosine. The blocking effect was similar with higher doses of aminophylline which temporarily increased coronary blood flow. The findings show that coronary vascular reactivity to dipyridamole and adenosine is maintained up to at least six hours after transplantation, and suggest that dipyridamole acts largely through aderosine. Propranolol does not increase coronary vascular resistance in the denervated heart. The aminophylline‐mediated increase in coronary vascular resistance could result from a blocking of the vasodilator effects of adenosine locally produced in non‐ischaemic myocardium.

ISSN:0004-945X    

DOI:10.1038/icb.1971.60

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryThe sera from BALB/c mice were found to contain uniformly high levels of inhibitors which actedin vitroby blocking the effect of colony stimulating factor in stimulating colony formation by mouse bone marrow cells. These inhibitors could be inactivated by ether extraction and heating and were removable by dialysis. The inhibitors exhibited partial species specificity, were not toxic for colony‐forming cells but led to the preture transformation of granulocytic cells to macrophages in developing colonies. Bone marrow cells from BALB/c mice contained lower numbers ofin vitrocolony‐forming cells and produced a lower percentage of granulocytic colonies when stimulated in culture than did cells from C57BL mice (a strain with low serum inhibitor levels). Mice with myelomonocytic leukaemia developed low serum inhibitor levels in the advanced stages of the disease.

ISSN:0004-945X    

DOI:10.1038/icb.1971.61

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryLenses dissected from 12‐day embryonic chicks, then incubated with rubella virus for varying periods of time, were subsequently found to have a shorter metabolic life in organ culture than those treated with uninfected RK13 cell extracts. In high concentrations of virus this inhibitory effect was rapid; with lower concentrations or shorter treatment time the effect was delayed. Virus could be isolated from the supernatant culture media 48 hours after removal of the original virus inoculum, but not subsequently. Distinct histopathological changes were usually apparent in lenses after 4 hours' incubation with rubella virus suspension, and extensive changes were present after 24 hours' incubation. Extract's of rubella‐infected RK13 cells from which rubella virus had been eliminated were also toxic to the lens. The early changes in this experimental system thus appear due to a direct toxic effect; the later changes may result from viral proliferation in the lens.

ISSN:0004-945X    

DOI:10.1038/icb.1971.62

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryA fluorescent histochemical technique has been applied to study human gingival tissue obtained at autopsy. Specific catecholamine fluorescence was demonstrated in the gingival arteries of infants, children and younger adults. A marked diminution in the specific fluorescence in the tissues from the older subjects was noted. Possible reasons for this loss of specific fluorescence are discussed.

ISSN:0004-945X    

DOI:10.1038/icb.1971.63

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryFollowing intravenous injection of rat plasma very low density lipoprotein labelled in the peptide moiety with125I into rats, there is an early appearance of radioactivity in the protein moiety of both low density lipoprotein and high density lipoprotein fractions. The suggestion that low density lipoprotein and high density lipoprotein are formed from very low density lipoprotein during its delipidationin vivowas investigated by injection ofin vitropartially and completely delipidated very low density lipoprotein. The evidence presented shows that very low density lipoprotein and low density lipoprotein can be formed from these labelled peptide fractions and that re‐entry of the very low density lipoprotein peptides into the biosynthetic pathway of plasma lipoproteins probably requires complete delipidation of the lipoproteins.

ISSN:0004-945X    

DOI:10.1038/icb.1971.64

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryWhen tested either by use as “organ culture feeder layers” or alternatively, by extraction prior to plating, several mouse tissues have been demonstrated to contain activity which stimulated colony development of mouse bone marrow cellsin vitroBy the “feeder layer” technique adrenal, tail tendon, bladder, heart, skeletal muscle, uterus and lung tissues consistently showed activity. By the extraction technique skeletal muscle, thymus, lung, spleen and kidney tissue from 12–14 day old mice and heart, thymus, brain, gut, spleen and lung tissue from 3–4 month old mice were active. Activity was also extracted from whole embryo, placenta, foetal membrane and pregnant uterus tissue, the last three tissues showing approximately 10–50 times more activity than other tissues on a wet weight of tissue per volume of extract basis.The active factor in an extract of pooled placenta, membrane and pregnant uterus tissues migrated in theβtoα2‐globulin region on starch‐Geon block clectrophoresis. had an apparent sedimentation coefficient (S20,w) of 3·8 S and was partially purified by batch chromatography on calcium phosphate gel.

ISSN:0004-945X    

DOI:10.1038/icb.1971.65

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryProtein was separated from carbohydrate in an endotoxin complex by partitioning with phenol‐water. A small portion of the protein ofV. cholerae569B endotoxin was capable of inhibiting the vibriocidal activity of anti‐protein antiserum. The isolated protein preparations each contained several different protein components and comparatively less vibriocidal inhibiting activity against an anti‐protein antisernm than the materials from which they were derived. The common inhibiting protein antigen was found in all the cholera strains tested but in different quantities.

ISSN:0004-945X    

DOI:10.1038/icb.1971.66

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryChanges in the concentration of IgG1, IgG2, IgM, IgA and albumin in serum and mammary secretion were studied in 15 cows and 2 heifers before and after parturition. Concentrations of IgG1and IgG2in blood serum 3–5 weeks before parturition were 13·38 ± 0·75 and 10·08 ± 0·39 mg/ml (means ± S.E.) respectively. In all animals the concentration of IgG1in serum decreased abruptly, usually by more than 50%, 2·3 weeks before parturition, and during the same period the concentrations of IgG2, IgM, IgA and albumin in serum remained unchanged. Four weeks after parturition the concentration of IgG1in serum had returned to values similar to those observed prior to the abrupt fall.Five weeks before parturition the concentration of IgG1in mammary secretion was, on average 11 times higher than that of IgG2. Highest concentrations of IgG1in secretion (113·89 ± 11·41 mg/ml) were observed 2–3 weeks before parturition in 16 of the 17 animals. The concentration of IgG2over the 5 weeks prior to parturition remained unchanged at levels of approx 30% of comparable values in serum. Concentrations of IgM (11·85 ± 0·53) and IgA (3·80 ± 0·20) in secretion collected prior to and immediately after parturition were, on average, 2 and 7 times higher respectively than those in serum.The sharp fall in the concentration of IgG1in serum in the absence of any suggestion of a concomitant decrease in IgG2concentration strongly suggests that the degradation hypothesis proposed by Brambell (1958, 1966) for selective transfer of protein across epithelial membranes does not hold for the mammary gland of the cow. The results support an alternative hypothesis based on the existence of IgG1‐specific receptor sites located on the basal or intercellular membrane of the glandular epithelial cells.

ISSN:0004-945X    

DOI:10.1038/icb.1971.67

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryTwo antigenic specificities have been detected in Australia antigens identified in Melbourne. One specificity was common to all antigens studied, the other was observed in approximately 50% of patients with Au‐positive acute viral hepatitis and also in all of a group of antigen‐positive institutionalized Mongols.In patients with acute viral hepatitis the antigenic type detected remained constant, even if a carrier state developed.

ISSN:0004-945X    

DOI:10.1038/icb.1971.68

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryTo determine whether selective absorption of immunoglobulin occurs in newborn unanaesthetised calves, the concentrations of IgG1, IgG2, IgM and IgA were measured in thoracic duct lymph shortly after the feeding of colostrum. In the 13 calves studied it was found that the concentrations of IgG1, IgG2, IgM and IgA in lymph expressed as a proportion of the concentration of the same immunoglobulins in the colostrum fed were not significantly different. It is concluded that immunoglobulins in the molecular weight range of 150,000 to 1,000,000 are absorbed non‐selectively in the calf.

ISSN:0004-945X    

DOI:10.1038/icb.1971.69

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY