Biomedical subjects

J Belleville

Publications and source records attributed to J Belleville.

At least 19 recordsLinked to original sources

PubMed2006

Effects of N-acyl-2-hydroxymethyl aziridines on in vitro proliferative responses of human lymphocytes stimulated by mitogens.

Aziridines have been shown to possess marked immunotropic activity. The aim of this work was to study the in vitro effects of different concentrations of three novel aziridines, 2-hydroxy-methyl-1-(N-phtaloylglycyl) aziridine (aziridine 1), 2-hydroxy-methyl-1-(N-phtaloylalanyl) aziridine (aziridine 2) and 2-hydroxy-methyl-1-(N-phtaloylphenylalanyl) aziridine (aziridine 3), on the proliferative responses of human lymphocytes stimulated by mitogens (concanavalin A (Con A) and lipopolysaccharide (LPS)), and interleukin-2 (IL-2), interleukin-6 (IL-6) secretion. The results showed that aziridines 1 and 3 significantly stimulated the resting and Con A or LPS lymphocyte proliferation at concentrations between 1 micromol/l and 1 mmol/l, in a dose-dependent manner, the action of aziridine 3 being the highest. They also increased IL-2 and IL-6 secretion. However, aziridine 2 had no effect on the resting lymphocyte proliferation in the absence of mitogens, at any concentration used, reduced Con A-stimulated T lymphocyte proliferation and LPS- stimulated B lymphocyte proliferation in a dose dependent manner and diminished IL-2 and IL-6 production. None of the three aziridines affected cell viability. In conclusion, the three aziridines used in this study displayed immunomodulatory properties. Aziridines 1 and 3 are potentially immunostimulant while aziridine 2 is immunosuppressive and could be used to provide nonspecific cell-mediated immune responses.

Aziridines↗

PubMed2004

Fish protein improves blood pressure but alters HDL2 and HDL3 composition and tissue lipoprotein lipase activities in spontaneously hypertensive rats.

The two-month effects of dietary fish protein and casein on VLDL, HDL(2) and HDL(3) compositions and hepatic lipase (HTGL) and tissue lipoprotein lipase (LPL) activities were examined in spontaneously hypertensive rats (SHR) at 4 wk of age. After 2 mo of experiment, the fish protein diet induced lower blood pressure (-14 %) as compared to casein. Liver triacylglycerol and total cholesterol concentrations were 1.37- and 1.71-fold lower in the fish protein group than in the casein group, respectively. Total cholesterol concentration in plasma was also diminished by fish protein (-21 %) and was reflected in HDL(2) fraction (-44 %). SHR fed the fish protein diet as compared with those fed casein, showed a significantly low HDL(3) particle number, as measured by diminished HDL(3) mass and apo A-I. The consumption of fish protein did not affect VLDL particle number, but significantly decreased VLDL-triacylglycerol (-32 %) and adipose tissue total lipid concentrations as compared to casein. This was accompanied by diminished HTGL and adipose tissue LPL activities (-10%, -91%, respectively). These data demonstrate that fish protein plays an antihypertensive role and reduces plasma and tissue lipid concentrations. Thus, a fish protein intake might be beneficial for patients with hypertension.

Animals↗

PubMed2003

Maximal voluntary eccentric, isometric and concentric torque recovery following a concentric isokinetic exercise.

To examine neuromuscular fatigue and recovery following an isokinetic fatiguing exercise, nine active females performed a fatiguing exercise comprising of ten sets of ten maximal concentric knee extensions. Before (pre-test), five minutes (post-test), 24 h and 48 h after the fatiguing exercise, maximal voluntary eccentric (-1.05 rad x s(-1); -2.09 rad x s(-1)), isometric (0 rad x s(-1)) and concentric (1.05 rad x s(-1); 2.09 rad x s(-1)) torque were measured. In order to distinguish central from peripheral factors involved in torque decrement, activation level (twitch interpolation technique) and twitch contractile properties were recorded. During the course of the fatiguing exercise, concentric torque was significantly lower during the 3rd set than pre-test (-5.6 +/- 12.3 %) and further decreased to the 10th (-10.3 +/- 9.5 %). Eccentric and isometric torques were significantly lower during post-test than pre-test (-16.8 +/- 8.8 % at -2.09 rad x s(-1), -15.1 +/- 7.4 % at -1.05 rad x s(-1), and -10.4 +/- 5.9 % at 0 rad x s(-1); p < 0.05), while concentric torque was not significantly modified. Voluntary activation, peak twitch torque, twitch maximal rates of force development and relaxation were also significantly declined (p < 0.05) at post-test. Twenty-four hours later, all the measured parameters were close to their pre-fatigue values. The present results reveal that the best way to test concentric-induced alteration of neuromuscular function was to use stressful testing conditions, such as eccentric contractions.

Adult↗

PubMed2002

Effect of dietary consumption, advanced age and overweight on the physical characteristics of cholesterol gallstones and biliary lipid composition in west Algerian women.

The aim of this study was to determine the effect of age, overweight and food consumption on the number and size of cholesterol stones and bile composition in west Algerian women undergoing surgery for cholelithiasis. Patients were divided into four groups according to body mass index (BMI, weight/height(2), kg/m(2)) and age. The highest number of patients with cholesterol gallstones was observed in the older women, in particular in those being overweight. In all patients, the stone number and size was approximately similar. The same dietary consumption was observed in older and young patients. Overweight patients were characterized by higher energy consumption (14.5 +/- 2.0 MJ x day(-1)) versus normal-weight patients (10.6 +/- 1.3 MJ x day(-1); p < 0.01) and versus Mediterranean diet (8 MJ x day(-1)). In normal-weight patients, the cholesterol saturation index (CSI) was higher in older patients (+56%) versus young patients while it diminished (-53%) in older overweight versus young patients. In older patients, the CSI was fourfold higher in normal-weight compared to overweight patients (p < 0.001). In conclusion, differences in food consumption were noted in overweight patients compared to normal-weight patients. Advanced age and overweight impaired biliary lipid composition, increased the number of patients with cholesterol gallstones but did not significantly affect the physical characteristics of west Algerian women.

Adult↗

PubMed2001

Implication of acyl chain of diacylglycerols in activation of different isoforms of protein kinase C.

We synthesized diacylglycerols (DAGs) containing omega-6 or omega-3 polyunsaturated fatty acids [i.e., 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG), 1-stearoyl-2-docosahexaenoyl-sn-glycerol (SDG), and 1-stearoyl-2-eicosapentaenoyl-sn-glycerol (SEG)] and assessed their efficiency on activation of conventional (alpha, beta I, gamma) and novel (epsilon, delta) protein kinase C (PKC). SAG exerted significantly higher stimulatory effects than SDG and SEG on activation of PKC alpha and PKC delta. Activation of PKC beta I by SEG and SDG was higher than that by SAG. Activation of PKC gamma did not differ significantly among DAG molecular species. Addition of SAG to assays containing SEG and SDG exerted additive effects on activation of alpha and epsilon, but not on beta I and gamma, isoforms of PKC. SDG- and SEG-induced activation of PKC delta was significantly curtailed by the addition of SAG. Three DAG species significantly curtailed the PMA-induced activation of beta Iota, gamma, and delta, but not of alpha and epsilon, isoforms of PKC. Our study demonstrates for the first time that in vitro activation of different PKC isoenzymes vary in response to different DAG species, and one can envisage that this differential regulation may be responsible for their in vivo effects on target organs.

Diglycerides↗

PubMed2001

Age-related changes in cholesterol metabolism in macrosomic offspring of rats with streptozotocin-induced diabetes.

The aim of this study was to determine the impact of diabetic macrosomia on cholesterol and lipoprotein metabolism. Age-related changes in the activities of serum LCAT, hepatic HMG-CoA reductase, cholesterol 7alpha-hydroxylase, and ACAT, the major enzymes involved in cholesterol metabolism, were determined in macrosomic offspring of streptozotocin-induced diabetic rats. Hepatic, serum, and lipoprotein cholesterol contents were also examined. Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin (40 mg/kg body weight) on day 5 of gestation. Control pregnant rats were injected with citrate buffer. At birth, macrosomic pups had higher serum, LDL-HDL(1), and HDL(2-3) cholesterol levels (P < 0.05) associated with increased LCAT activity (+57%) compared with control values. At 1 and 2 months of life, serum and lipoprotein cholesterol concentrations in macrosomic rats were similar to those of controls, whereas LCAT activity remained elevated about 1.5-fold. In addition, there was no change in hepatic cholesterol contents but hepatic HMG-CoA reductase, cholesterol 7alpha-hydroxylase, and ACAT activities were higher in both macrosomic males and females than in their respective controls (P < 0.01). By 3 months, macrosomic rats had developed hypercholesterolemia with a rise in all lipoproteins. Enzyme activities were still increased in these mature macrosomic rats, and hepatic cholesteryl esters were higher only in macrosomic females. These data demonstrate an overproduction, combined with overutilization, of cholesterol during the phase of rapid growth in macrosomic rats. However, cholesterol oversynthesis exceeded its removal and was a major contributor to hypercholesterolemia in adult macrosomic rats. In conclusion, macrosomia was associated with alterations in cholesterol metabolism through adulthood.

Acetyl-CoA C-Acyltransferase↗

PubMed2000

Dietary protein level and origin (casein and highly purified soybean protein) affect hepatic storage, plasma lipid transport, and antioxidative defense status in the rat.

The effects of different proportions (10, 20, and 30%) of dietary casein or highly purified soybean protein on lipid metabolism were studied in growing Wistar rats. Hepatic, plasma and lipoprotein lipid, and protein concentrations, plasma thiobarbituric acid-reactive substance (TBARS) levels, and resistance of red blood cells against free-radical attack were determined after a 4-wk dietary regimen. Compared with the 20% casein diet, the 20% soybean protein diet exhibited similar cholesterolemia but lower plasma triacylglycerol concentrations and very-low-density lipoprotein (VLDL) particle number, as measured by diminished contents of VLDL-triacylglycerol, VLDL-protein, and VLDL-apolipoprotein (Apo) B (B-100 and B-48). The soybean protein diet raised high-density lipoprotein (HDL)(2-3) particle number, as measured by enhanced concentrations of HDL(2-3) cholesterol, HDL-phospholipid, and HDL-ApoA-I. Increasing casein or soybean protein level (from 10 to 30%) in the diet involved higher VLDL-ApoB (B-100 and B-48), indicating an increase in the number of VLDL particles. Feeding the 30% casein or 30% soybean protein diet enhanced LDL-HDL(1) cholesterol contents. Despite similar HDL(2-3)-ApoA-I levels, the 30% casein diet enhanced the HDL(2-3) mass and its cholesterol concentrations. In contrast, feeding either the 10 or 30% soybean protein diet significantly lowered HDL(2-3) cholesterol and ApoA-I levels. These effects on cholesterol distribution in lipoprotein fractions occurred despite unchanged total cholesterol concentrations in plasma. Feeding 20% soybean protein versus 20% casein involved lower plasma TBARS concentrations. Decreasing casein or soybean protein levels in the diet were associated with higher plasma TBARS concentrations and had a lower resistance of red blood cells against free-radical attack. The present study shows that dietary protein level and origin play an important role in lipoprotein metabolism and the antioxidative defense status but do not affect total cholesterol concentrations in plasma.

Animals↗

PubMed2000

Low-protein diet prevents tissue lipoprotein lipase activity increase in growing rats.

The time course of changes in tissue lipolytic activities was studied in young rats during the consumption of a low-protein diet containing 50 g protein/kg (40 g wheat gluten +10 g casein/kg) for 28 d followed by balanced refeeding with 200 g protein/kg (160 g wheat gluten +40 g casein/kg) for 28 d. Lipoprotein lipase (LPL) activities were compared with the values of a control group fed a balanced diet containing 200 g protein/kg for 56 d. At the end of protein malnutrition period, the epididymal fat tissue LPL activity represented 36 %, and that of heart and gastrocnemius was 44 %, of those of the control group. These differences were accompanied by lower serum- and VLDL-triacylglycerols (TAG), respectively 47.6 % and 31 % of the control group values, probably resulting from reduced synthesis of VLDL-apolipoproteins (29 % of control group values), concomitant with liver lipid accumulation (4.8-fold) and little lipid storage in epididymal fat tissue. At day 2 of refeeding, there was no significant difference in liver and epididymal fat tissue LPL activities between experimental and control rats. At the end of the refeeding period, LPL activity of epididymal fat and liver lipolytic activity had increased and became similar to control group values. The consumption of a low-protein diet prevented the increase in extrahepatic LPL activities as observed in the control group. The alterations in LPL activity suggest that a low-protein diet limits lipid storage in adipose tissue due to reduced serum VLDL-TAG availability.

Analysis of Variance↗

PubMed2000

Time course of changes in serum glucose, insulin, lipids and tissue lipase activities in macrosomic offspring of rats with streptozotocin-induced diabetes.

The aim of this investigation was to determine the time course of changes in serum glucose, insulin and lipid levels, as well as lipid and protein content and lipolytic activities in insulin target organs (liver, adipose tissue and muscle), in macrosomic offspring of streptozotocin-induced mildly hyperglycaemic rats. Food intake and nutritional efficiency were also evaluated. Mild hyperglycaemia in pregnant rats was induced by intraperitoneal injection of streptozotocin (40 mg/kg body weight) on day 5 of gestation. Control pregnant rats were injected with citrate buffer. At birth, macrosomic pups (birth weight >1.7 S.D. greater than the mean value for the control pups) had higher serum insulin, glucose and lipid levels than control pups. These macrosomic rats maintained accelerated postnatal growth combined with high adipose tissue weight up to 12 weeks of age. These rats were not hyperphagic; however, they had higher food efficiency and fat storage capacity with higher adipocyte lipoprotein lipase activity, which contributed to persisting obesity. Hepatic lipase activity was increased in macrosomic rats at all ages. Moreover, macrosomia was associated with metabolic disturbances that varied according to age and sex. After 1 month, several alterations observed at birth had disappeared. Serum glucose, insulin and lipid levels in male and female macrosomic rats became similar to those of their respective controls. At 2 months of age, hepatic and serum triacylglycerol levels were higher in macrosomic females than in controls. By 3 months, macrosomic rats (both males and females) had developed insulin resistance with hyperinsulinaemia, hyperglycaemia, and higher serum and hepatic lipids. In conclusion, macrosomia was associated with alterations in glucose and lipid metabolism through to adulthood. It should be considered as an important potential risk factor for obesity and its metabolic complications.

Adipose Tissue↗

PubMed2000

Maternal and fetal serum lipid and lipoprotein concentrations and compositions in type 1 diabetic pregnancy: relationship with maternal glycemic control.

The aim of this study was to determine maternal and fetal lipoprotein profiles in type 1 diabetic pregnancies differing in glycemic control. Serum lipid, apolipoprotein, and lipoprotein lipid concentrations were investigated in mothers with poorly controlled or well-controlled type 1 diabetes as reflected by hemoglobin A1c(HbA1c) concentrations performed by isolab column chromatography and in their macrosomic (body wt = 4650 +/- 90 g) or appropriate-for-gestational-age newborns (body wt = 3616 +/- 68 g), and these levels were compared with those in healthy mothers and in their control newborns (body wt = 3290 +/- 45 g). In mothers with well-controlled diabetes and in their infants, serum lipid, apolipoprotein, and lipoprotein lipid concentrations were comparable to those in control mothers and in their control newborns. Mothers with poorly controlled diabetes presented higher serum triglyceride and apoprotein B-100 (apo B-100) levels but lower apo A-I and HDL3 cholesterol and phospholipid levels as compared with control values. In their macrosomic newborns, all serum lipid, apolipoprotein, and lipoprotein lipid levels were higher than those in control newborns. Maternal HbA1c and triglyceride levels in late gestation were significant predictors of fetal lipids and lipoproteins in the poorly controlled diabetes group. In conclusion, when under good metabolic control, type 1 diabetes did not affect maternal and fetal lipid levels. However, when under poor metabolic control, type 1 diabetes is associated with maternal and fetal lipoprotein abnormalities.

Adult↗

PubMed2000

Fetal macrosomia related to maternal poorly controlled type 1 diabetes strongly impairs serum lipoprotein concentrations and composition.

AIMS: To determine the effects of fetal macrosomia related to maternal type 1 diabetes on the lipid transport system. METHODS: Serum lipoprotein concentrations and composition and lecithin:cholesterol acyltransferase (LCAT) activity were investigated in macrosomic newborns (mean birth weight, 4650 g; SEM, 90) and their mothers with poorly controlled type 1 diabetes, in appropriate for gestational age newborns (mean birth weight, 3616 g; SEM, 68) and their mothers with well controlled type 1 diabetes, and macrosomic (mean birth weight, 4555 g; SEM, 86) or appropriate for gestational age (mean birth weight, 3290 g; SEM, 45) newborns and their healthy mothers. RESULTS: In mothers with well controlled type 1 diabetes, serum lipids, apolipoproteins, and lipoproteins were comparable with those of healthy mothers. Similarly, in their infants, these parameters did not differ from those of appropriate for gestational age newborns. Serum triglyceride, very low density lipoprotein (VLDL), apolipoprotein B100 (apo B100), and high density lipoprotein (HDL) triglyceride concentrations were higher, whereas serum apo A-I and HDL3 concentrations were lower in mothers with diabetes and poor glycaemic control than in healthy mothers. Their macrosomic newborns had higher concentrations in all serum lipids and lipoproteins, with high apo A-I and apo B100 values compared with appropriate for gestational age newborns. In macrosomic infants of healthy mothers, there were no significant differences in lipoprotein profiles compared with those of appropriate for gestational age infants. LCAT activity was similar in both groups of mothers and newborns. CONCLUSION: Poorly controlled maternal type 1 diabetes and fetal macrosomia were associated with lipoprotein abnormalities. Macrosomic lipoprotein profiles related to poor metabolic control of type 1 diabetes appear to have implications for later metabolic diseases.

Adult↗

PubMed2000

Impaired serum lipids and lipoproteins in fetal macrosomia related to maternal obesity.

The aim of this work was to determine lipoprotein metabolism alterations in macrosomic newborns and to see whether these lipoprotein abnormalities are parallel or not to those found in their obese or nonobese mothers. Serum lipids, apo A-I, apo B100, lipoproteins (VLDL, LDL, HDL2, and HDL3), and LCAT activity were investigated in obese and nonobese mothers and cord blood of their macrosomic or appropriate-for-gestational-age (AGA) newborns. Serum and VLDL triglyceride concentrations were higher in obese mothers of AGA newborns than in nonobese mothers. Serum triglyceride, VLDL, and apo B100 levels were higher, while serum apo A-I and HDL2 cholesterol concentrations were lower in obese mothers of macrosomic newborns than in the other groups. In their macrosomic newborns, serum lipid, lipoprotein, apo B100, and apo A-I levels were higher as compared with those of other newborns. Macrosomic newborns of nonobese mothers had lipoprotein profiles similar to those in AGA newborns. LCAT activity was similar in both mother groups and in both newborn groups. In conclusion, maternal obesity and fetal macrosomia were associated with lipoprotein abnormalities consistent with high atherogenic risk.

Adult↗

PubMed1999

Changes in serum lipid and lipoprotein concentrations and compositions at birth and after 1 month of life in macrosomic infants of insulin-dependent diabetic mothers.

The aim of this study was to determine whether macrosomia related to maternal diabetes alters lipoprotein metabolism and whether these abnormalities still persist or regress after 1 month of life. Serum lipoprotein compositions and concentrations as well as serum lipid fatty acid compositions were investigated in macrosomic infants (birth weight = 4840 +/- 105 g at term) of insulin-dependent diabetic mothers at birth and after 1 month of life, and were compared to those of control infants (birth weight = 3400 +/- 198 g at term) of healthy mothers. Compared to controls, at birth, macrosomic newborns had higher serum lipids, apolipoprotein A-I and B-100, and lipoprotein (very low density lipoprotein, low density lipoprotein, high density lipoprotein-2 and high density lipoprotein-3) levels. Higher percentages of C18:2n-6 in serum triacylglycerols, phospholipids and cholesteryl esters were also observed. At day 30, in macrosomics, serum triacylglycerol, apo B-100, very low density lipoprotein and low density lipoprotein levels were still significantly higher. C18:2n-6 and C18:3n-3 contents in serum phospholipids, triacylglycerols and cholesteryl esters were reduced while C20:4n-6 and C22:6n-3 contents in serum phospholipids and cholesteryl esters were enhanced, compared to control values. Macrosomia was associated with alterations in lipoprotein compositions and concentrations at birth, some of which persisted after 1 month of life, and might play a role in the pathogenesis of diabetes and atherosclerosis in adult life.

Case-Control Studies↗

PubMed1998

Low birth weight at term impairs cord serum lipoprotein compositions and concentrations.

UNLABELLED: The purpose of this study was to determine the effect of low birth weight at term on serum lipoproteins. Lipid and apolipoprotein (apo) contents were investigated in cord sera of small-for-gestational-age (SGA) newborns at term (2290 g +/- 33 g) and compared with those of appropriate-for-gestational-age (AGA) newborns (3570 g +/- 93 g). In SGA newborns, VLDL amounts were twofold higher, whereas LDL, HDL2 and HDL3 contents were lower than in AGA newborns (-38%, -44% and -42%, respectively). VLDL-triacylglycerols (TG), apo B-100 and apo E were higher, while VLDL-apo C-II values were 39% lower in SGA newborns compared with those of AGA newborns. In SGA newborns, HDL2-apolipoprotein, phospholipid and cholesteryl ester levels were respectively reduced to 70%, 50% and 40% compared with AGA values. HDL3-apolipoprotein and phospholipid contents were also decreased in SGA newborns (-43% and -60%, respectively). The different HDL2 and HDL3-apolipoproteins (apo A-I, A-II, C-III and E) were significantly decreased in SGA newborns. CONCLUSION: Intra-uterine growth retardation was accompanied by alterations in apolipoproteins and lipid compositions in the four lipoprotein fractions, which may impair lipid metabolism. Follow up studies on lipoprotein patterns in SGA infants are required to investigate whether such abnormalities at birth lead to diseases in adulthood.

Apolipoproteins↗

PubMed1998

Digestion and absorption rates of [3H]-oleic acid and [14C]-triolein do not differ in rats fed heated (-) and (+) gossypol cottonseed and soybean flours.

This study was conducted to compare in vivo the acute effects of heated (+) and (-) gossypol cottonseed flours with those of soybean flour on lipid digestion and absorption in growing rats. Rats were fed by gastric intubation mixed [3H]-oleic acid and [14C]-triolein with heated flours or without flour (control). Lipid digestion and absorption were determined for 6 h after meal intubation. Both radioactivities recovered in gastrointestinal tract were significantly higher in rats fed (+) gossypol cottonseed flour than in all other groups. The majority of both recovered radioactivities was found in stomach contents, then in stomach wall and finally in intestinal wall. The distribution of both radioactivities at different gastrointestinal levels was similar. In stomach contents and wall, [14C]-radioactivity was primarily in triacylglycerols, but was also recovered in free fatty acids and diacylglycerols. In intestinal wall (mucosa + tunica) [3H]-radioactivity was found at greatest levels in free fatty acids, then in triacylglycerols and diacylglycerols. Greatest [14C]-radioactivity was found in triacylglycerols, then in free fatty acids, in diacylglycerols and last in phospholipids in rats fed the three flours. Therefore no quantitative differences in lipid digestion and absorption were observed among the rats fed the three flours. In conclusion, both cottonseed flours slowed lipid digestion and absorption compared with soybean flour and this delay was greater in the rats fed (+) gossypol cottonseed flour than in those fed (-) gossypol cottonseed flour. However, this inhibiting effect was probably too low to induce physiologically important effects on lipid digestion or absorption.

Animals↗

PubMed1998

Highly purified soybean protein is not hypocholesterolemic in rats but stimulates cholesterol synthesis and excretion and reduces polyunsaturated fatty acid biosynthesis.

The specific effects of soybean protein on lipid metabolism were determined with highly purified soybean protein. At 5 wk of age, growing rats were fed diets containing 20% highly purified soybean protein or casein supplemented or not with 0.1% cholesterol for 2 mo. Plasma and liver lipid composition, fecal steroid excretion and several hepatic enzyme activities were measured. There were no significant dietary protein-related differences in plasma and liver cholesterol concentrations. When diets were cholesterol free, highly purified soybean protein stimulated fecal neutral and acidic steroid excretion associated with concomitantly higher hydroxy methylglutaryl CoA (HMG-CoA) reductase activity, but lower cholesterol 7alpha-hydroxylase activity. Soybean protein lowered the linoleate desaturation index [20:4(n-6)/18:2(n-6)] in liver microsomal lipids and phospholipids. This may have been due to the reduced microsomal Delta6(n-6) desaturase activity in rats fed soybean protein, whereas Delta5(n-6) desaturase activity did not differ between groups fed the two proteins. Cholesterol supplementation (0.1%) did not affect plasma cholesterol but increased liver cholesterol and triacylglycerol concentrations and reduced HMG-CoA reductase activity; this latter effect was greatest in rats fed soybean protein. Cholesterol 7alpha-hydroxylase activity, however, was diminished only in rats fed casein. Desaturase activities, and particularly Delta5(n-6) activity, were lowered by cholesterol supplementation in rats fed both protein diets, including a significantly lower 20:4(n-6)/18:2(n-6) ratio in liver microsomal lipids and liver phospholipids. Thus although dietary proteins have no effect on serum cholesterol in rats, they affect enzyme activities involved in cholesterol metabolism and fatty acid desaturation.

Animals↗

PubMed1998

[Recovery of muscle contractility after a strength training session: mechanical, neurophysiologic and biochemical approach].

The purpose of this study was to observe the recovery of maximal strength immediately after a maximal eccentric strength training set. The trained female subjects (n = 8) performed 10 bouts of 10 maximal eccentric contractions of the quadriceps muscle. Each bout was separated by a 2 minutes rest period. Integrated electromyogram (iEMG) of the vastus medialis and the rectus femoris, and torque were measured before, just after, 24 and 48 hours after training session, at different knee angular velocity (-60, 0, 60, 120, and 240 degrees.s-1). Possible structural damage of the muscular cell were searched from the urinary concentration of some protein catabolism metabolites before (basal rate), 24 and 48 hours after the exercise. Maximal torque significantly fell for any angular velocity immediately after the training session: 13.6% at -60 degrees.s-1, 16.9% at 60 degrees.s-1, 7.5% at 120 degrees.s-1, 12.8% at 240 degrees.s-1 and 8.6% at 0 degree.s-1. This event was accompanied by an increase of the iEMG at the training angular speed, and by an increase of the metabolites concentration in a half part of the subjects. Strength developed during eccentric contraction showed the earliest recovery. And it even significantly overshot its initial level by 14.9% at 48 hours. A significant increase of the iEMG assessed at the eccentric velocity was then observed. In the same time, 3 of the 6 subjects showed an increase of their urinary concentration of the chosen metabolites in comparison with their initial values. This result may closely be connected with the supercompensation phenomenon, which first appears in the training mode. This phenomenon could partly be explained by the associated increase of the iEMG.

Adult↗

PubMed1997

Hepatic storage and transport of n-3 and n-6 polyunsaturated fatty acids by very-low-density lipoproteins in growing rats fed low- or adequate-protein diets with sunflower, soybean, coconut, and salmon oils.

Protein and essential fatty acid (EFA) deficiencies may both occur in chronic malnutrition and have common symptoms. To determine the interactions between dietary protein intake and EFA availability, rats were fed purified diets containing 20% or 2% casein and 5% as one of four fats (sunflower, soybean, coconut, or salmon oil) that differed particularly in their n-6 and n-3 polyunsaturated fatty acids (PUFAs). Protein malnutrition enhanced hepatic triacylglycerol and cholesterol concentrations while decreasing hepatic protein and phospholipid contents and mass and components of very-low-density lipoprotein (VLDL). The ratio of PUFAs to saturated fatty acids (SFAs) was consistently depressed by protein malnutrition in liver and VLDL triacylglycerol and phospholipid. Total n-6 and n-3 fatty acids were diminished by protein malnutrition, except with salmon oil, with which a decrease in 20:5n-3 was compensated for by an increase in 22:6n-3. The ratio of 20:4n-6 to 18:2n-6 was enhanced in liver phospholipid and VLDL triacylglycerol, and modified little in liver triacylglycerol. Generally, the ratio of 20:3n-9 to 20:4n-6, an index for EFA deficiency, was raised with protein malnutrition in liver triacylglycerol and phospholipid and in VLDL triacylglycerol. The extent of changes in each fatty acid proportion varied according to the oil fed. Overall, VLDL-apolipoprotein concentrations were, in general, strongly reduced with protein malnutrition. In conclusion, protein malnutrition may accelerate marginal EFA deficiency and decrease long-chain PUFA bioavailability and thus increase EFA requirement.

Animals↗