摘要:

Abstract.The rate of incorporation of leucine into hepatic proteins in liver slices from 42 patients was studied. Zero order kinetics for the incorporation of leucine in relation to the incubation time and to the amount of incubated proteins were obtained, provided that the medium contained a complete amino acid mixture with a concentration 4 times that of normal human serum. — Inulin space and water content of the preparation were of the same magnitude as reported for rat liver. The presence of fructose (5.5 mM) in the medium caused an inhibition of the rate of incorporation of leucine into proteins. Insulin in the medium, however, stimulated the incorporation rate. — Assuming that the rate of incorporation of leucine into hepatic proteins is representative of protein synthesis, the half‐life of liver proteins can be calculated to be 35 days for subjects below 60 years of age. For those who were older than 60 years, the protein turnover rate was approximately 30% h

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02353.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract.Extrahepatic cholestasis in man is known to be associated with high phosphoglyceride and cholesterol concentrations in serum. Moreover, an abnormal lipoprotein, often referred to as lipoprotein‐X (LP‐X), appears in serum in cases of extrahepatic cholestasis.The purpose of this study was to determine the rate of incorporation of precursors into hepatic lipids and proteinsin vitroand to compare these changes with the lipoproteins in plasma in patients with extrahepatic cholestasis. The rate of incorporation of glycerol into triglycerides and into different classes of phosphoglycerides was determined. The rate of incorporation of leucine into proteins was also determined in liver slices from 15 patients with extrahepatic cholestasis and compared with controls. In cholestatic liver tissue, the rate of incorporation of glycerol into choline phosphoglycerides and into ethanolamine phosphoglycerides was significantly increased. The rate of incorporation of leucine into hepatic proteins was also increased significantly in these patients. The results suggest that the changed metabolism of phospholipids and protein in liver tissue in cholestatic conditions may contribute to the changes in the serum lipoprotein patt

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02354.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract.The turnover of14C‐cholic acid and3H‐chenodeoxycholic acid was studied in hyperlipaemic patients before and during treatment with cholestyramine. — In five female patients with hyperlipoproteinaemia type IIa the pool size and turnover of cholic acid as well as the total formation of bile acids were significantly lower than in female normolipaemic controls. During treatment with cholestyramine, cholic acid synthesis rose 4–18 fold and the turnover of chenodeoxycholic acid increased about twice. In three of the patients these changes were associated with a normalization of the serum cholesterol levels. Mainly due to the high turnover of cholic acid, total bile acid synthesis was above the normal range in the five male patients with hyperlipoproteinaemia type IV. During treatment with cholestyramine, the serum lipids and cholic acid formation remained unchanged but the turnover of chenodeoxycholic acid increased by a factor of about two. This resulted in a decrease of the abnormally high initial ratio between the formation of cholic acid and chenodeoxycholic acid. The unequal response to cholestramine treatment is taken to be a further indication that hyperlipoproteinaemia type II and type IV are different entities of disease affecting cholesterol and bile acid met

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02355.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract.A method for fractionating isolated fat cells is described. After fixation with osmium tetroxide, the cells are passed through a series of polyamide filters of decreasing mesh width and the number of cells on each filter is counted. — Isolated fat cells fromad libitumfed rats weighing 85–580 g were incubated with [U‐14C]‐glucose (0.55 mM), fixed with osmium tetroxide and fractionated according to size. When the cells were obtained from one animal the conversion of glucose to neutral lipids per cell increased with increasing cell size just as well in the absence of insulin as in the presence of insulin (10 mU/ml). The following results were obtained from comparisons between animals of different weight: in the absence of insulin, the lipogenesis for cells of the same size remained constant irrespective of the rat weight, whereas in the presence of insulin the lipogenesis for cells of the same size decreased markedly when the rat weight exceeded about 300 g. It is Concluded that factors other than the cell sizeper se(e.g. age, degree of obesity) determine the responsiveness to insulin. — The hormone‐stimulated lipolysis was studied on unfractionated cell samples fromad libitumfed rats of different weights and the following was found: the glycerol release per 106cells induced by ACTH and norepinephrine in maximally stimulating concentrations increased with increasing mean cell size or rat weight. In contrast, the glucagon‐induced lipolysis of cells from rats weighing 300–400 g was smaller than that of cells from rats wei

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02356.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract.Some patients with liver dysfunction show a marked hypertriglyceridaemia, a phenomenon most frequently accompanied by cholestasis.In this report we have identified, isolated and characterized an abnormally large (300–700 Å), triglyceride rich, low density lipoprotein, (d 1.019‐1.063 g/ml) designated β‐lipoprotein (β2‐LP), from the plasma of patients with hypertriglyceridaemia secondary to liver disease. The βa‐LP differs significantly in its percent composition and protein moiety from the unique lipoprotein‐X (LP‐X) specific for cholestasis and also from normal β‐lipoproteins, both of which are also present in the patients LDL fraction. Furthermore, some evidence is provided suggesting that the β2‐LP is likely to represent an intermediate particle of chylomicron metabolism, which accumulates in this disease due to a markedly diminished

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02357.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract.A glucose‐containing tetrasaccharide (13 mg/24 h) was isolated from the urine of a ten year old boy with the “childhood form” of glycogen storage disease type II (Pompe's disease). The structure, established by sugar analysis, methylation analysis, optical rotation and enzymatic degradation was found to be α‐D‐Glcp(lr̊6)‐α‐D‐Glcp(l r̊ 4).α‐D‐Glcp(1r̊4)‐D‐Glc. The same compound was also isolated in small amounts (1 mg/24 h) from normal urine. Larger glucose‐containing oligosaccharides, not detected in normal urine were also present in

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02358.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract.In order to explain the pathogenesis of protein depletion in chronic uraemia, 13 measurements of albumin catabolism were performed in uraemic patients undergoing haemo‐or peritoneal dialysis treatment, during either the early phase or steady uraemic state.Catabolism was determined during a single haemo‐or peritoneal dialysis by a double tracer technique (Human Serum Albumin and sodium iodide labelled with two different isotopes of iodine). The output from both albumin and iodine systems was measured in the dialysis solution flowing out from the peritoneum or artificial kidney. The radioactive iodide arising in dialysate from albumin breakdown was concentrated by the use of an anion exchange resin.Catabolic rate was three times the normal in 3 patients showing clinical features of hypercatabolism (true rapid loss of body weight) in the early phase of uraemia, or during relapse of it; albumin turnover rate returned to normal in 2 of these patients, when measured during clinical steady state conditions. This behaviour suggests highly increased catabolism, not counterbalanced by a correspondingly increased synthesis, as the cause of albumin depletion in chronic urae

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02359.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract.Loops of dog small intestine and colon have been subjected to two hours' acute ischaemia and their recovery has been studied by functional and histological examinations. — Immediately after the ischaemia, both organs show serious necrotic lesions of the mucosal surface, their active transport capacities are abolished, mucosal Na+‐K+‐ATPase activities are reduced, and a significant liberation of acid phosphatase into the efferent blood is observed. The lesions of the ileal loops are more severe than those of the colonic loops. — The ileal loops have a finite, albeit greatly reduced function 24 hours after the trauma. After 3 days, amino‐acid transport has normalised but sugar transport is still reduced. Histological examination confirms that epithelial cells cover the villi of most samples after 24 hours, and normalisation is almost complete after three days. All parameters are normal after one week. — In five cases out of eight, the colonic mucosa is replaced by a compact polymorphonuclear infiltration bathing in a haemorrhagic exudate 24 hours after the ischaemic period; it is evidently quite functionless. In three loops the mucosa is preserved, but only one had functional activity. Three days after the trauma, functional activity is finite, but lower than that of the control loops; histological study reveals a disorganised mucosa, often with ulcers surrounded by relatively healthy tissue. At seven days, mean transport capacity is normal but there are still pathological signs at the microscopic level. — The results show that the ileum is more sensitive to ischaemic damage, but has a greater regenerative potential than the colon. There is a good relationship between the functional and structural state o

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02360.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract.The effect of acute uraemia on glucose and urea formation by isolated perfused livers of fasting rats was investigated.The basal gluconeogenesis following nephrectomy was significantly increased as compared to normal and sham operated controls. Enhanced glucose formation was associated with an increase in both urea synthesis and output of the poorly metabolizable amino acids valine, leucine, and isoleucine. In the presence of a mixture of amino acids (serine, threonine, lysine, glutamic acid, ornithine, and citrulline) all added at near physiological concentrations, the stimulating effect of uraemia on gluconeogenesis was further enhanced. This was paralleled by an increased formation of urea and an increased uptake of the amino acids. It is concluded that acute uraemia may stimulate glucose synthesis by increased substrate supply. This seems to be achieved by at least two different mechanisms, namely increased protein degradation and accelerated amino acid utilization.

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02361.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract.The effects upon immunoreactive insulin (IRI) release of beta cell membrane modifications induced by pronase, a mixture of proteolytic enzymes extracted fromStreptomyces griseus, have been studied in isolated islets of Langerhans. Pretreatment of the islets for 90 min with 4 μg/ml pronase did not modify their IRI content; it slightly increased the basal rate of IRI release and potentiated the secretory response to glucose, leucine and tolbutamide during incubation. In perifused islets, the rapid phase of IRI secretion in response to glucose was more markedly enhanced than the late phase. After preincubation with 4 μg/ml pronase, glucose‐induced IRI release was reversible and abolished in the absence of calcium. Pretreatment for 90 min with 500 μg/ml pronase decreased IRI content of the islets by approximately 25% and provoked a pronounced but transient rise of basal IRI release. This was considered to be a leakage of IRI from damaged beta cells since it persisted in a medium deprived of calcium. The rapid secretory phase in response to glucose was preserved in perifused islets whereas the late phase was markedly reduced. The secretory responses to leucine and tolbutamide were almost completely obliterated. When pretreatment with pronase was carried out in a calcium‐depleted medium, basal IRI release from islets preincubated with 500 μg/ml pronase was only slightly increased whereas IRI secretion induced by glucose was inhibited by 40 and 65%, respectively in islets pretreated with 4 and 500 μg/ml pronase. These results indicate that pronase‐induced modifications of the beta cell membrane influence IRI secretion in a way which depends on the concentration of the enzyme and the presence of extracellular calcium. They are considered to support the hypothesis that membrane systems are involved in IRI releasing

ISSN:0014-2972    

DOI:10.1111/j.1365-2362.1974.tb02362.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY