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Biomedical subjects

A Mazur

Publications and source records attributed to A Mazur.

At least 127 records · Page 7Linked to original sources
PubMed1993

Hepatic apolipoprotein B synthesis in copper-deficient rats.

The present study was designed to examine if induction of apolipoprotein B synthesis is associated with hypercholesterolemia in copper-deficient rats. This hypercholesterolemia mainly resides in an increase in the HDL-1 and LDL and is associated with a significant increase in plasma apoB concentration. Liver apoB mRNA levels were not significantly modified in deficient animals as compared to control rats. Studies on liver apolipoprotein synthesis indicated that apoB100 synthesis was increased in deficient animals whereas apoB48 synthesis was unchanged. Thus, it appears that the increase in apoB synthesis in the liver of copper-deficient rats occurs at the posttranscriptional level. The selective increase in apoB100 synthesis indicates the possible impact of this deficiency on the editing of apoB. An increase in apoB100 synthesis by the liver in copper-deficient rats may significantly contribute to the increase in plasma concentration of LDL.

Animals↗
PubMed1993

The effect of dietary fruits and vegetables on urinary galactitol excretion in galactose-1-phosphate uridyltransferase deficiency.

Even on a lactose-restricted diet, urinary galactitol excretion and erythrocyte galactose-1-phosphate levels are persistently elevated in patients with galactose-1-phosphate uridyltransferase deficiency. In order to determine the contribution of galactose in dietary fruits and vegetables to this phenomenon, (1) the content of galactose in a lactose-free diet was directly measured when a galactosaemic patient's diet was specifically enriched in those fruits and vegetables which contain relatively large amounts of free galactose and (2) galactitol excretion was determined during ingestion of this diet for 3 weeks and while on a synthetic diet for 1 week that provided < 8 mg galactose/day. For comparison the effect of a 3-week supplementation of 200 mg galactose/day was determined. The measured intake in total foodstuffs matched the theoretical content of galactose in the patient's diet based on amounts in fruits and vegetables alone, thus supporting the concept that fruits and vegetables are primarily responsible for galactose intake in a lactose-free diet. All of the dietary manipulations, however, had relatively little effect on metabolite levels, suggesting that endogenous galactose production is primarily responsible for the elevated levels of galactose metabolites routinely detected in patients on lactose-restricted diets.

Adolescent↗
PubMed1993

Oxidative modification of triglyceride-rich lipoproteins in hypertriglyceridemic rats following magnesium deficiency.

Hypertriglyceridemia observed in magnesium (Mg)-deficient rats was associated with a significant increase in the very low-density lipoprotein (VLDL) plus low-density lipoprotein (LDL) fractions. The results from in vitro copper-induced lipid peroxidation, expressed in terms of conjugated dienes and thiobarbituric acid reactive substances content, showed that VLDL + LDL particles from Mg-deficient rats were more susceptible to oxidative damage than lipoproteins from control rats. These results suggest that the mechanism responsible for the atherogenicity and tissue damage characteristic of Mg deficiency may be mediated by an increased susceptibility of triglyceride-rich lipoproteins to peroxidation in hypertriglyceridemic animals.

Animals↗
PubMed1993

Dietary magnesium affects susceptibility of lipoproteins and tissues to peroxidation in rats.

Magnesium (Mg)-deficient and control diets were pair-fed to weanling Wistar rats for 8 days. Plasma lipoproteins were separated into various density classes by sequential preparative ultracentrifugation. The extent of lipid peroxidation was measured in terms of thiobarbituric acid reactive substances in lipoproteins and tissue homogenates before or after iron-induced lipid peroxidation. Hyperlipemia in Mg-deficient rats was accompanied by increased oxidation of very-low-density lipoproteins and low-density lipoproteins. Moreover, very-low-density lipoproteins and high-density lipoproteins from Mg-deficient rats were more susceptible to oxidative damage following iron incubation. Mg deficiency increased lipid peroxidation in liver, heart and skeletal muscles. Their homogenates were more susceptible to in vitro peroxidation. Mg deficiency has been discussed as a possible contributory factor in the development of cardiovascular disease and was associated with tissue damage and membrane alteration. These results demonstrate for the first time that Mg affects the susceptibility of lipoproteins to peroxidation and suggest that the mechanism responsible for the pathological consequences of Mg deficiency may be mediated by lipid peroxidation products.

Animals↗
PubMed1993

Copper deficiency increases the susceptibility of lipoproteins and tissues to peroxidation in rats.

Male Wistar rats were pair-fed from weaning for 6 wk either a copper-deficient diet or a control diet containing sucrose. Hypercholesterolemia in copper-deficient animals was associated with a significantly greater plasma apolipoprotein B concentration and modifications in the lipid composition of triglyceride-rich lipoproteins containing apolipoprotein B. The proportion of triglycerides was elevated and the proportion of cholesterol was reduced in the VLDL + LDL fractions from copper-deficient rats compared with control animals. When the VLDL + LDL fractions were subjected to in vitro copper-induced oxidation, the lipoprotein fractions from copper-deficient rats were more susceptible to oxidative damage than lipoprotein fractions from control rats as indicated by the rate of diene conjugation. Hydroperoxide and thiobarbituric acid-reactive substance (TBARS) measurements performed 3 h after the induction of peroxidation were in agreement with the greater formation of conjugated dienes. Concentrations of TBARS were significantly greater in heart homogenates from copper-deficient rats compared with control rats. After exposure of tissue homogenates to iron-induced lipid peroxidation, TBARS were significantly higher in liver and heart from copper-deficient rats compared with control rats. Of particular importance is the observation that copper deficiency has a harmful effect on lipid peroxidation in the cardiovascular system.

Animals↗
PubMed1993

Age-related response to dietary fructose in the rat: discrepancy in triglyceride and apolipoprotein B synthesis as a possible mechanism for fatty liver induction in adult rats.

The effects of fructose feeding on plasma and liver lipids, triglyceride secretion, and plasma apolipoprotein B and their liver mRNA level were studied in young and adult rats. We have shown that the responsiveness of adult rats to dietary fructose differs from that of young rats with regard to body parameters as well biochemical analyses. In young rats, fructose diet causes a coupled induction of liver triglyceride and apolipoprotein B synthesis via increased mRNA level. In adult rats it appears that triglyceride secretion is lower and less inducible by dietary fructose than in young rats. This insufficient export of the excess of synthesized triglycerides may cause fatty liver in adult animals. Reduced adaptation of liver lipoprotein secretion to dietary carbohydrates in adult animals may be explained by the failure to stimulate apolipoprotein B synthesis at the mRNA level in these rats.

Age Factors↗
PubMed1993

[Prognosis in treatment of addiction in alcoholics].

It is assumed by the author that the pre-addiction personality as well as probable events which could directly precede excessive drinking (understood even as a main cause) are, in the practice of a therapist, less important than the fact that a person who abuses alcohol will sooner or later complicate his or her life and arising difficulties will motivate per se his or her further drinking. Thus, reaching for alcohol activates a progressive rhythm which, with passing time, becomes autonomic against an individual genesis of addiction, and a difficult situation which an addict does not want or is not able to solve or does not understand at all that it results from an excessive drinking, becomes a crucial point. Therefore, the prognosis in treatment of alcoholics depends mainly on the patient's awareness of casual interrelationship between his difficult situation and excessive drinking. Following the studies of a large group of examined and treated alcohol addicts, "rather positive" prognosis applied to only 10% out of 718 persons while 40% remained with definitely "negative" prognosis.

Alcoholism↗
PubMed1993

Magnesium and ageing. I. Experimental data: importance of oxidative damage.

Magnesium status may be compromised with ageing for two reasons: insufficient intake (magnesium deficiency) or alterations in magnesium metabolism (magnesium depletion). There is a large volume of literature suggesting that magnesium deficit contributes to the ageing process and to the vulnerability to age-related diseases. One of the biological changes associated with ageing is an increase in free radical formation with subsequent damage to cellular processes. Prime targets of the more reactive free radicals are unsaturated lipids in cell membranes, amino acids in proteins, and nucleotides in DNA. The accumulation of unrepaired oxidative damage products may be a major factor in cellular ageing. Magnesium-deficient animals show an increased susceptibility to an in vivo oxidative stress and their tissues are more susceptible to in vitro peroxidation. Moreover, the protective properties of various antioxidant drugs and nutrients suggest that free radicals are involved in the injury process of magnesium deficiency. The consequences on stress susceptibility, defective membrane functions and perturbation of intracellular calcium metabolism, inflammation, cardiovascular diseases including atherosclerosis and ischaemia/reoxygenation injury, diabetes, fibrosis, immune dysfunction and other diseases associated with ageing are presented and discussed.

Aging↗
PubMed1993

The effect of dietary fiber on apolipoprotein A-I and A-IV gene expression in rat intestine.

The effect of the dietary fiber on apo A-I and apo A-IV mRNA levels was studied in the intestine of rats fed either by fiber-free or high-fiber diets. Rats fed high-fiber diet had lower plasma cholesterol concentrations than animals fed fiber-free diet. A proximal-distal apo A-I and apo A-IV mRNA gradient was found in both groups. High-fiber diet feeding reduced apo A-I mRNA levels in jejunum and ileum and ileal apo A-IV mRNA levels as compared to fiber-free diet fed rats. The obtained results suggest that some dietary fibers may play a role in regulation of lipoprotein metabolism in the intestine, including apolipoprotein synthesis.

Animals↗
PubMed1992

The effect of dietary copper on rat plasma apolipoprotein B, E plasma levels, and apolipoprotein gene expression in liver and intestine.

The plasma levels of apo B and apo E, and the level of hepatic and intestinal mRNA coding for these apolipoproteins were investigated in weanling male rats pair-fed for 6 wk with a control or copper-deficient diet. Plasma cholesterol, triglycerides, and phospholipids were significantly increased, and plasma apo B and apo E levels were also markedly increased in copper-deficient rats as compared to control rats. Copper deficiency significantly increased triglyceride levels and decreased cholesterol levels in the liver. No major differences in the levels of hepatic and intestinal apo B and apo E mRNA occurred between control and copper-deficient rats. These data imply that hypertriglyceridemia dn hypercholesterolemia owing to the copper deficiency are not accompanied by modifications in the gene expression at the mRNA level in the liver and intestine of the apolipoproteins studied.

Animals↗
PubMed1992

Effects of dietary fermentable fiber on fatty acid synthesis and triglyceride secretion in rats fed fructose-based diet: studies with sugar-beet fiber.

In an attempt to elucidate the role of the dietary fermentable fiber in reduction of hyperlipidemia, we substituted 30% wheat starch with 30% sugar-beet fiber in rats fed a fructose-based (41% fructose), low-fat (2% corn oil) diet. Male Wistar rats ate the test diets for 3 weeks. Feeding the sugar-beet fiber (SBF) diet resulted in a significant enlargement of the cecum; it also increased the concentration of volatile fatty acids compared with rats fed a fiber-free (FF) diet. Feeding SBF decreased plasma triglyceride and cholesterol concentrations in the postprandial as well as the postabsorptive period. In the liver, triglyceride levels were depressed in concert with the decreased liver lipogenesis and the post-Triton triglyceride secretion. Liver cholesterol levels were unaffected by SBF diet feeding. SBF-fed animals were markedly less fat compared with fiber-free-diet-fed rats. Adipose tissue lipogenesis was depressed in the postprandial period in SBF-fed animals. In short, this study suggests that substitution of easily digested carbohydrates by certain fermentable fibers may play an interesting role in the reduction of hyperlipidemia and obesity.

Animals↗
PubMed1992

Magnesium and blood pressure. I. Animal studies.

The relationship between experimental magnesium deficiency and blood pressure is complex and still the subject of much debate. The effect of Mg deficiency and blood pressure in Wistar rats receiving a Mg deficient diet (0.080 g/kg) for 40 weeks was examined. Deficient rats, when compared to controls, showed an initial transitory phase of hypotension, followed by normalization of blood pressure and then hypertension beginning after 15 weeks on the deficient diet. During the whole experimental period, heart rate was significantly increased in deficient rats as compared to controls. The fact that hypotension resulting from Mg deficiency of short duration can be inhibited by antihistamines and by indomethacin suggests that various mediators seen during the inflammatory period of Mg deficiency could be involved. Mg deficiency of long duration was accompanied by hypertension. When Mg-deficient rats received the control diet for a period of 3 weeks, Mg supplementation only partially corrected the hypertension. The hypertension was not a consequence of stimulation of the renin-angiotensin system since the plasma renin activity was not modified and ACE activity was reduced. These deficient rats showed a significantly lower vasopressor response to noradrenaline than control rats. Several factors such as increase in collagen, changes in elastin and arterial elasticity, total lipid content, and calcifications may account for the hyporesponsiveness to contractile agonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Lipoprotein metabolism in fatty liver dairy cows.

High yielding dairy cows undergo a period of energy deficit in early lactation and mobilise body reserves for milk production. During this phase lipid infiltration of the liver takes place as a result of fat mobilization and the degree of accumulation of fat in the liver depends on the level of mobilization of fatty acids from the adipose tissue. The objective of the studies reported was to characterize plasma lipoproteins in dairy cows and to determine whether differences in plasma lipoproteins existed in dairy cows with varied degrees of hepatic lipid infiltration. The physiological mechanism responsible for fatty liver is not fully understood but seems to involve a deficit in the hepatic synthesis and release of lipoproteins as shown by the depressed level and compositional modifications of plasma lipoproteins. Other results indicate a negative correlation between plasma apo B concentration and liver triglyceride content. In studies carried out on fatty liver cows the level of liver apo B mRNA was reported to be lower than in control cows. An impaired synthesis of apo B may result in its decreased availability for lipoprotein formation and in turn results in enhanced triglyceride accumulation in the liver.

Animals↗
PubMed1991

Apolipoprotein B gene expression in rat intestine. The effect of dietary fiber.

The effect of the dietary fiber on apo B mRNA level was studied in the intestine of rats that were fed either fiber-free or high-fiber (30% sugar-beet fiber) low-fat diets for 3 weeks. The fiber diet studied does not affect jejunal apo B mRNA levels but decreases the level of ileal apo B mRNA. In the rat cecum, in both fiber-free and fiber groups, we failed to detect the apo B mRNA. The test fiber diet feeding markedly increased fecal bile salt and cholesterol excretions. We suggest that dietary fiber can modify apo B expression in the intestine. The increased fecal bile salt excretion might be involved in such a modification.

Animals↗
PubMed1991

Effect of magnesium deficiency on post-heparin lipase activity and tissue lipoprotein lipase in the rat.

Previous studies have provided evidence that Mg deficiency affects lipid metabolism. The present experiments were designed to assess whether the hypertriglyceridemia associated with Mg deficiency was related to alterations in post-heparin lipase activity (PHLA). Mg-deficient and control diets were pair-fed to weanling Wistar rats for eight days and plasma lipoproteins were separated into various density classes by sequential preparative ultracentrifugation. Triglycerides were significantly increased in chylomicrons and in the very low density lipoprotein, low density lipoprotein and high density lipoprotein (HDL) fractions. Cholesterol and phospholipid levels were significantly lower in the HDL fraction. PHLA in deficient rat was substantially lower than in control rats. The inverse correlation between plasma triglyceride concentration and PHLA strongly suggests that hypertriglyceridemia is the result of defective lipolysis of plasma triglycerides in Mg-deficient rats. Further examination of the PHLA was carried out by salt-mediated inhibition of lipoprotein lipase (LPL) and by heparin sepharose affinity chromatography and purified rat LPL antiserum. The results indicate that hepatic lipase is significantly decreased in Mg-deficient rats but the low PHLA is due mainly to a decline in LPL. However, total LPL activity, that is, both the intracellular and the extracellular pools of LPL in adipose tissue, heart and diaphragm, were unaffected by Mg deficiency. The results suggest that the decrease of LPL activity in the plasma of Mg-deficient rats may be due to a selective decrease in the heparin-releasable pool of enzyme.

Adipose Tissue↗
PubMed1991

Intellectual outcome in children with maple syrup urine disease.

We report a controlled study of intellectual outcome in 16 children with maple syrup urine disease (MSUD) that compares the outcome of MSUD diagnosed after symptoms became apparent with that of MSUD diagnosed prospectively and in unaffected siblings and parents. The mean IQ (+/- SD) score in the children with classic MSUD was 78 +/- 24; however, there were two discrete groups: one with normal IQ (greater than 84) whose MSUD had been diagnosed at a mean age of 3.5 days and a second group, with IQ below normal, whose MSUD was diagnosed at a mean of 10 days of age. Affected children treated presymptomatically had higher IQ scores than their affected siblings treated when their disease was symptomatic. Multiple regression analysis indicated that the important influences on IQ were age at the time of diagnosis and long-term metabolic control; control at the time of testing also might have affected performance. The mean score of unaffected siblings was 92 +/- 5 and the mean parental IQ was 83 +/- 9. The mean IQ scores of children with variant MSUD, 97 +/- 4, was similar to that of their parents, 103 +/- 6. This study was not longitudinal and thus could not identify subtle developmental learning problems. We conclude that early and meticulous treatment of MSUD can result in intellectually normal children.

Adult↗