ISSN:0250-6807    

DOI:10.1159/000176363

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The average western diet contains approximately 40% of total calories as dietary fat or approximately 100 g of fat. The efficiency of the entire process of fat absorption can be judged by the fact that under normal conditions less than 5% of ingested fat is recovered in the stool. In the past several years, new concepts have greatly added to our understanding of the process by which dietary fat is digested, absorbed and processed in the intestinal epithelial cell for delivery to the body via the intestinal lymph and the portal venous system. These newer concepts include an understanding of the physical chemistry of lipids, the physiology of bile salts and the formation and metabolisms of lipoprotein all directly influencing the process of fat absorption. The present discussion will emphasize the formation of lipoproteins within the intestinal mucosa. New information suggests that the small intestinal mucosa is a quantitatively important source of lipoprotein constituents for systemic lipoproteins. This is hardly surprising when one considers the large quantities of lipid traversing the intestinal mucosa each day which must exit in the form of lipoproteins.

ISSN:0250-6807    

DOI:10.1159/000176364

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

In vitro data suggest that low-density lipoprotein (LDL) is bound to specific receptors located in pits on the surface of fibroblasts by a high-affinity process and subsequently undergoes catabolism in lysosomes. This binding seems to be mediated by ionic interaction between LDL and its receptor, the latter being totally or partially absent from the fibroblasts of patients with familial hypercholesterolaemia (FH). In vivo data suggest that LDL is also catabolised by a concentration-dependent, low-affinity pathway which is probably mainly located in the liver. LDL catabolism is reduced in FH and after saturated fat feeding, whereas polyunsaturated fat has the reverse effect. Hypocatabolism of LDL alters LDL composition, accelerates atherosclerosis and may lead to premature death from coronary heart disease.

ISSN:0250-6807    

DOI:10.1159/000176366

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Adult rats fed a diet containing 14%, by weight, of protein displayed a negative N balance when energy intake was reduced to a value approximating basal metabolism. A positive N balance was induced, however, by raising the protein concentration in the diet, and N retention continued until body fat reserves were almost exhausted. These findings are in conflict with the widely-held view that N equilibrium can be achieved only when the need for energy is satisfied.

ISSN:0250-6807    

DOI:10.1159/000176312

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Among the cholesterol-carrying lipoproteins, low-density lipoproteins (LDL) have been associated with coronary heart disease as a risk factor while high-density lipoproteins (HDL) appear to protect against coronary heart disease. According to studies with cells in tissue culture, control mechanisms of receptor-mediated LDL uptake are important in maintaining the cholesterol balance within the arterial cells. HDL may be a vehicle for transporting cholesterol from peripheral cells to the liver. Recent results, derived from studies of patients affected with Tangier disease (absence of HDL in plasma), favor the hypothesis that HDL precursors (e.g. surface remnants of chylomicrons) may be more potent in cholesterol uptake than mature HDL.

ISSN:0250-6807    

DOI:10.1159/000176367

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

140 adult hospitalized Thai patients were assessed for their nutritional status. The prevalence of protein-calorie malnutrition in these patients based on various parameters was as follows: 73.2% according to weight-height, 80.0% accroding to triceps skinfold thickness, 60.7% according to upper arm muscle circumference, 50.4% according to hair root morphology and 66.2% according to serum albumin level. These data reflected the disproportionate loss of the patients’ body tissues. Severity of protein-calorie malnutrition was also detected by physical signs. Anemia and vitamin deficiencies were present in some of the patients. This study signifies that intensive nutritional management should be done to combat hospital malnutritio

ISSN:0250-6807    

DOI:10.1159/000176313

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Monolayer cultures of normal human fibroblasts were used to study the effects of the main subclasses of high-density lipoproteins, HDLa and HDL3, on 3-hydroxy-3-methylglutaryl CoA reductase (EC 1.1.1.34) activity. In this system, HDL3 (d= 1.125–1.210 g/cm3) specifically induced HMG-CoA reductase activity. Evaluation of culture dynamics revealed that enzyme induction was restricted to the stationary phase of growth. When the cells were incubated with HDL2 (d = 1.063–1.125 g/cm3), suppression of reductase activity was observed. Mixtures of HDL2 and HDL3 suppressed reductase activity when HDL2 was greater than 35% of the total HDL. The suppressive effects of HDL2 were abolished by treatment with cyclohexanedione and restored by regeneration of the arginyl residues, suggesting an apoprotein-mediated suppressive mechanism. These observations show that the cellular effects of HDL depend upon the stage of cell growth and the ratio of HDL subclasses in HDL as usually isolated.

ISSN:0250-6807    

DOI:10.1159/000176368

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Rats were physically trained by treadmill running and fed normal, high fat, or identical diets supplemented with 1.0% DL-carnitine. Fatty acid oxidation, stimulated by exercise and/or by a high fat diet was studied to determine if it might be further augmented by supplemental dietary carnitine. Fatty acid oxidation in vitro or in vivo was unaffected by carnitine feeding. Carnitine feeding was associated with an increase in heart and muscle palmitylcarnitine acyltransferase activity and reduced serum cholesterol in trained rats fed the high fat diet. Under the conditions of this study, supplemental dietary carnitine did not greatly alter glyceride synthesis, lipolysis, or fatty acid oxidation, which indirectly indicates that the increased demands for fatty acid oxidation resulting from exercise or from fat feeding are adequately supported by endogenous levels of carnitine.

ISSN:0250-6807    

DOI:10.1159/000176314

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

High-density lipoproteins (HDL) are macromolecular complexes of lipids and proteins which float in the ultracentrifuge between densities of 1.063 and 1.21 g/l. A major division of HDL into two subclasses according to their specific density has been proposed: HDL2 (d= 1.063–1.125) and HDL3 (d= 1.125–1.21). The division is supported by the different proportions of lipids and apoproteins in the two subclasses and by evidence suggesting that the protective effect of HDL lies mostly in the HDL2 subclasses. Recent epidemiological, experimental and clinical data have supported a probable role or HDL as an anti-risk factor due to their negative correlation with the prevalence of ischaemic heart disease. Some of these data are presented and discussed in this paper.

ISSN:0250-6807    

DOI:10.1159/000176369

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Albino rats were malnourished from neonatal to weanling stage by increasing the litter size. The in vivo incorporation of (1-14C)-acetate, (1-14C)-palmitate into the lipid classes was examined in the animals. A stimulated incorporation of the label was observed in total lipids, phospholipids, cholesterol, cerebrosides and sulfatides of the brain of malnourished animals compared to controls.

ISSN:0250-6807    

DOI:10.1159/000176315

出版商:S. Karger AG    

年代:1980

数据来源: Karger