摘要:

Abstract.Proximal and distal tubular segments of the subcapsular nephron and segments of the ascending limb of Henle's loop were dissected out freehand from lyophilized kidney section of male rats after bilateral adrenalectomy. The microdissected nephron structures were weighed with a quartz fibre balance. Na K ATPase was determined by analyzing the total ATPase and the Mg ATPase in dissected material. As soon as 6 h after adrenal enucleation a 65% reduction of Na K ATPase activity in the ascending limb of Henle's loop and a 81 % diminution in the distal convoluted portion were detected; 24 h after adrenalectomy an additional reduction of the transport enzyme in the proximal convoluted portion was simulated by an enzyme activity increase in the sham‐operated controls. In contrast to previous authors working with homogenate or membrane fraction of the whole kidney, the present quantitative histochemical results indicate a close adaptation of Na K ATPase to the altered sodium transport in rat kidney after adrenalectom

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1971.tb00636.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract.The absorption and gastric metabolism of L‐dopa (L‐dihydroxyphenylalanine) were studied in 14 Parkinsonian patients. Patients were given p. o. 25 μCi (500 mg)14C L‐dopa labelled at the β‐carbon mixed with 2 g polyethylene glycol as a dilution marker. Absorption was evaluated by determining the gastric rate of absorption, gastric clearance, serum levels, and urinary excretion of14C. L‐dopa and its metabolites in the gastric juice and serum were fractionated by column chromatography. Patients with gastric juice pH of 1.2‐2.1 had a gastric rate of absorption of 62.6±4.7 mg/h with a gastric clearance of 31.7.4.1 ml/h. The gastric emptying time was 228±96min. 17.2–26.4% of total radioactivity in the gastric juice were dopa metabolites. Patients with gastric pH of 6.9‐7.2 had a very rapid emptying time (an average of 22 min.) with no gastric absorption. The amount of metabolites in their gastric juice was insignificant. Gastric absorption and emptying time were reduced in patients when the gastric pH was raised to 3.5‐4.5 with antacids. Serum peak concentrations were higher and more rapidly achieved in patients with high gastric pH than in those with low pH.The most rapidly achieved and highest serum peak levels were observed in patients with partial gastrectomy and in those who were given the drug by duodenal infusion. It appears that direct absorption of L‐dopa by the stomach may be limited by gastric metabolism of the drug, a possibility supported by the study in vitro of human stomach tissue obtained at surgery. The inverse relationship between the gastric emptying time and serum levels suggests that the intestine is the major site of L‐dopa absorption. Thus factors that prolong gastric emptying time may lower serum levels of L‐dopa by delaying access of the drug to the site of absorption and by increasing m

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1971.tb00637.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract.The intestinal59Fe absorption from ferri‐ and ferro‐haemogIobin‐59Fe and59Fe3+and59Fe+was calculated from whole body‐59Fe‐retention measurements in subjects withnormalanddepletediron stores. A ferri‐haemoglobin‐59Fe/ferro‐haemoglobin‐59Fe absorption ratio of 1.03 ±0.11 was observed for the absorption of ferri‐haemoglobin‐59Fe (8.6± 0.77%) and ferro‐haemogIobin‐59Fe (8.7±0.94%) in persons withnormaliron stores.Depletionof iron stores caused a slight but significant higher rise of ferri‐haemoglobin‐59Fe absorption (22 ± 1.7%) than the increase of ferro‐haemoglobin‐59Fe absorption (18 ±0.9%) so that the absorption ratio was 1.24±0.073.—This remarkable iron valence independence of haemoglobin iron absorption is in considerable contrast to the well‐established valence dependence of inorganic iron absorption which favours ferrous iron absorption especially with rising iron doses. The59Fe3+/59Fe2+absorption ratio for a diagnostic 0.56 mg Fe dose increased from 0.43 in subjects withnormaliron stores to 0.74 in persons withdepletediron stores, whereas this absorption ratio was augmented only from 0.21 to 0.28 for the therapeutic 50 mg Fe‐dose.—The different influence of iron valence on iron absorption from inorganic and haemoglobin iron supports other evidence for the existence of two separate mechanisms for

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1971.tb00638.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract.In the control subject, plasma angiotensin production is a linear function of plasma renin content. Upon incubation of this same plasma in the presence of an excess of homologous renin, angiotensin production is finally limited by the plasma content of renin substrate (PRS). By this method, PRS levels were measured and compared with levels of plasma renin activity (PRA), urinary aldosterone excretion, and sweat sodium and potassium content, in sixteen normal human subjects, aged twenty‐five to thirty years, under three defined metabolic conditions: unrestricted sodium intake, salt depletion, constant sodium intake plus administration of desoxycorticosterone acetate (DOCA).1) Unrestricted Sodium Intake.In these control subjects, in perfect health, there exist important individual differences in PRS levels. The PRS levels seem to be quite constant for a given subject under a given metabolic condition: the levels remained the same after a four month interval for a given subject.2) Salt Depletion.Activation of the renin‐angiotensinaldosterone system (RAAS), as shown by an elevation of PRA and of urinary aldosterone excretion, is accompanied by a decrease in PRS levels.3) Constant Sodium Intake Plus Administration of DOCA.Inactivation of the RAAS, as shown by lowering of PRA and of urinary aldosterone excretion, is accompanied by a marked elevation of PRS levels.It would appear that, in human control subjects there exists an inverse relationship between PRS and PRA lev

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1971.tb00639.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract.Dichloromethylenediphosphonate (Cl2MDP) and ethane‐l‐hydrory‐l,l‐diphosphonate (EHDP), two compounds related in structure to inorganic pyrophosphate but which contain P—C—P instead of P—O—P bonds, have been shown to inhibit the osteoporosis induced by the immobilisation of the hind limbs of rats. These effects may be due to the ability of diphosphonates to inhibit bone resorption. A polyphosphate and porcine calcitonin inhibited the osteoporosis only slightly. Diphosphonates may prove useful in the therapy of osteoporosis and other diseases in which bone resorpti

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1971.tb00640.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract.The kinetic parameters of plasma triglyceride metabolism were determined in 14 adult subjects with the nephrotic syndrome by endogenous labelling of circulating triglyceride with tritiated glycerol. The triglyceride production (turnover) rate and theapparentKmof removal were calculated from the slope of the radioactivity disappearance curve and compared to a normal control material studied previously. Plotting of the individual data in a log scale of triglyceride concentration versus turnover with the normal area and saturation curves in the background allowed a detailed characterization of the nature of kinetic alterations occurring in disease. It was found that in the majority of cases with the nephrotic syndrome the plasma triglyceride concentration and rate of influx are slightly above normal. However, theapparentKmof removal was significantly increased suggesting that efflux may also be somewhat impaired. In four cases the plasma triglyceride was produced at a rate which exceeded the value predicted by the normal saturation curves and it is believed that an uncontrolled overproduction of plasma triglyceride was present in these cases.—Complete remission of disease in one case brought both triglyceride concentration and turnover rate rapidly to normal values. An eight‐hour infusion of human serum albumin in another patient promptly caused a return of high triglyceride turnover to normal.— The primary change behind the nephrotic hypertriglyceridaemia seems to be a controlled increase of plasma triglyceride synthesis. In some cases, however, this overproduction occurs in an uncontrolled fashion and in a number of patients decrease of removal efficiency contributes to the development of hyperglyceridaemia. All of these changes can be explained on the basis of an increased FFA/albumin molar ratio in plasma giving rise to the elevation of unbound FFA fra

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1971.tb00641.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract.In liver disease the proportion of plasma cholesterol present in the form of ester is lower than that found in normal subjects. Recent work has suggested that a plasma enzyme, lecithin: cholesterol acyltransferase (LCAT), may be a major f actorin the physiological regulation of plasma cholesterol ester levels. In patients with a variety of hepatobiliary disorders LCAT activity was found to be reduced and a study of the effects of interaction between normal and jaundiced plasmas supported the hypothesis that the low LCAT activity was due mainly to a reduction in the plasma concentration of the enzyme.When bile salts were added to an in vitro system clear evidence of inhibition of LCAT was produced only with concentrations higher than those normally found in the plasma of patients with liver disease. This casts doubt on the suggested role of bile salts as in vivo inhibitors of the enzyme.The cholesterol ester concentration of plasma showed good correlation with its LCAT activity when this was measured in a standard substrate. Our results suggest that reduction in LCAT activity may be an important factor in the production of the low ester: free ratio found in almost all hepatic disorders.

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1971.tb00642.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1971.tb00643.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY