摘要:

SummaryThe dilutions of labelled red blood cells and labelled albumin were studied over a 10 hour period in HbA and HbB sheep, both before and after splenectomy.The dilution curves were analysed into exponentials, and values for red blood cell volume and plasma volume were calculated from various portions of the curves.Dilution curves for labelled red blood cells in intact sheep showed. important differences from those in splenectomized sheep.Red blood cell volume was calculated from: The extrapolation of the exponential process with the slowest decay rate; the sum of intercepts of all exponential processes; jugular haematocrit and plasma volume. Splenectomy significantly reduced the values for these parameters.Plasma volume was calculated from the extrapolation of the exponential with the slowest decay rate and from the sum of intercepts of all exponential processes. Splenectomy significantly reduced the values for these parameters. Blood volume and the value for the ratio of body to jugular haematocrit were calculated from the data, and were found to be significantly reduced by splenectomy.Differences between HbA and HbB sheep were found only for jugular haematocrit and red blood cell volume calculated from jugular haematocrit and plasma volume.The differences in values from the several methods of calculating red blood cell volume in intact sheep and the reduction of these values by splenectomy are discussed in relation to the splenic red blood cell content.

ISSN:0004-945X    

DOI:10.1038/icb.1971.12

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryThe reflex effect of applying ice to the neck on hand blood flow has been examined in normal and synipathectomised subjects. Within and among normal subjects the magnitude and time‐course of the response is reproducile. There was no difference in response between cool and warm hands.

ISSN:0004-945X    

DOI:10.1038/icb.1971.13

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryThe binding of lipid to proteins isolated from rat liver was investigated by incubating ultrasonically dispersed mixtures of phospliolipids and neutral lipids with3H‐lahelled proteins. After incubaation the lipid‐protein eomplexes were separated from the imbound protein by preparative ultracen‐ trifugation at d = 1·21.Gonsiderable binding of soluble (105,000 × g supernatant) and “solubilised” membrane (endoplasmic reticulum) protein to lipid occurred after incubation for 90 min. at 37°, whereas plasma proteins under similar conditions were not significantly bound to lipid. These observations suggest that the binding of liver protein to lipid, as measured in these experiments, was due to specific binding of liver proteins with lipid, rather than the result of non‐specific adsorbance. Alteration of the phospholipid: neutral lipid ratios appreciably influeneed the amonnt of protein bound, and the lipid‐protein interaction was found to be dependent on time and temperature.

ISSN:0004-945X    

DOI:10.1038/icb.1971.14

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryDerivatives of the protein ferritin, differing in their net charge, were presented to cultures of peritoneal macrophages, HeLa, KB and L cells. Unmodified ferritin was not taken up by the continuons line cells. However, as the negative charge carried by the inulecule was reduced, a point was reached when these cells would take up the test protein. The continuous line cells bchaved as a homogeneous population in the sense that either all or none of the cells in the culture would take up a particular protein. The macrophage culture did not behave in this way. A small proportion of the macrophage population would pinocytose the untreated ferritin and as the negative charge carried by the molecule was decreased the proportion of cells taking up the protein increased markedly. The penetration of protein into KB cells was only observed when the test protein would bind to the cell surface. The adsorbed protein fixes to the eell surface in a patchy manner and does not form a uniform layer over the whole surface. The pattern of adsorption suggtests that there are well defined receptor areas on the cell surface where binding can occur.

ISSN:0004-945X    

DOI:10.1038/icb.1971.15

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryPortal occlusion selectively inhibits thein vivoincorporation of [14C]formate into the purines of deoxyribonucleic acid isolated from rat lymph nodes and thymus compared with incorporation into deoxyribonucleic acid thymine. Incorporation of formate into deoxyribonucleic acid purines is also low in perfused submandibular lymph nodes and in lymph nodes incubatedin vitro. A similar depression of formate incorporation into lymphoid tissue deoxyribonucleic acid purines is obtained by treatment with the immuno‐ suppressive drugs azathioprine and 9‐butylazathioprine.

ISSN:0004-945X    

DOI:10.1038/icb.1971.16

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryA pressure‐box was used to reduce mean perfusion pressure in the upper limb. Pressure‐flow curves for the skin of the hand and forcann were‐ constructed under a variety of conditions. The blood flow to the skin of the forearm was examined by plethysmosraphy before and after adrenaline ionto‐ phoresis, after alterations to the local thermal environment and after body‐ heating. The skin of the hand was examined by the latter two technique's and by heat‐flow discs. No evidence was fonnd for antorcgulation of blood flow in skill under any of these circumstances.

ISSN:0004-945X    

DOI:10.1038/icb.1971.17

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummarySome of the peripheral actions of clonidine have been investigated in nonnal volunteers. Close intra‐nrterial administration of clonidine (125–500 μg./min.) into the brachial artery caused a rapid constriction of the skin vessels in the foreann and the hand. The response was dose‐dependent and did not show tachyphylaxis during a thirty minute infusion. It was absent in the presence nl adrenerjjic alpha receptor blockade, which indicates a sympathometic mode of action. Reflex vascular sympathetic responses were still elicited during the intra‐arterial infusion, therefore neuronal or alpha receptor block was not present at the doses of clonidine used.Intravenous infusion of 150 μg. clonidine caused a 16% fall in mean arterial pressure, a biphasic change in calculated hand vascular resistance and a fall in heart rate. The patteni of vascular resistance changes reflects a direct vasocon‐ strictor action of the drug which is then overshadowed by its central sympathetic inhibitory action. The vasoconstrictor response to intra‐arterial nonitlrenaline was greater during the hypotension produced by clonidine. Similarly, tbe pressor response to intravenous noradrenaline was accentuated at this time. At least with acute administration of clonidine to man, reduced vascular responsiveness cannot play any part in the hypotension which occurs.

ISSN:0004-945X    

DOI:10.1038/icb.1971.18

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryIntracellular lipid droplets (“pre‐chylomicrons”) have heen isolated from intestinal epitliclial cells of ruts which had heen fed fat. Techniques were used which prevented contamination hy chylomicrons or digestion products. The pre‐chylomicrons differed in composition from chyloimicrons in several ways. They contained more free fatty acid, more free cholesterol and more protein, and the phospholipid complement was different from chylomicrons.The extra protein associated with pre‐chylomicrons was membranous; histocheinical, hiochemical and isotopic evidence indicated that it was derived from Golgi memhrane. It is proposed that the Golgi apparatus is concerned with transport of fat particles out of the absorptive cell to form chylomicrons in intestinal lymph.

ISSN:0004-945X    

DOI:10.1038/icb.1971.19

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryThe effects of bilateral destruction of the bypotlialamic “feeding” centre on tbe fasting blood sugar level, glucose alworption and glucose tolerance in the rat were investigated. It was fund that lesions in this area do not directly influence these aspects of glucose metabolism.Bilateral lesions in the “feeding” centre produced a market and protracted elevation of the glucose tolerance curve after adniinistnition of a glucose load. However, this effect was evidently due to dehydration resulting from adipsia. Dehydration produces the same type of glucose tolerance curve in control animals without hypothalamic lesion.

ISSN:0004-945X    

DOI:10.1038/icb.1971.20

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY

摘要:

SummaryA chloroform‐methanol extract ofMycoplasma pneumoniaereacted with bovine antisera toMycoplasma mycoidesin a complement fixation test. Some antisera gave higher titres with theM. pneumoniaeantigen than with the homologous antigen; absorption of the antisera withM. mycoidesantigen reduced the titres to either antigen by approximately the same amount. Absorption of antisera withM. pneumoniaeantigen greatly reduced the titre of antisera toM. pneumoniaeantigen but the titre to the homologous antigen was reduced fourfold or less. It is concluded that only some of the complement fixing antigens ofM. mycoidesare shared withM. pneumoniae.

ISSN:0004-945X    

DOI:10.1038/icb.1971.21

出版商:Nature Publishing Group    

年代:1971

数据来源: WILEY