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.

Moving droplets on asymmetrically structured surfaces

It is shown theoretically and experimentally that a liquid droplet can move on a surface structured with a locally asymmetric pattern when a breathing of the drop is induced by external means. Two different situations can be envisioned: a drop whose volume is modulated and a drop whose equilibrium contact angle is switched between two extreme values. This last case was experimentally investigated using electric fields acting on water droplets in castor oil. The main trends of the theory are verified although a quantitative analysis would necessitate either a simpler experimental geometry or a more elaborate model. The results are discussed with a miniaturization of the setup in mind which would have important potential applications in the field of integrated analysis systems.

Energy transduction of isothermal ratchets: generic aspects and specific examples close to and far from equilibrium

We study the energetics of isothermal ratchets which are driven by a chemical reaction between two states, and operate in contact with a single heat bath of constant temperature. We discuss generic aspects of energy transduction such as Onsager relations in the linear response regime as well as the efficiency and dissipation close to and far from equilibrium. In the linear response regime where the system operates reversibly, the efficiency is in general nonzero. Studying the properties for specific examples of energy landscapes and transitions, we observe in the linear response regime that the efficiency can have a maximum as a function of temperature. Far from equilibrium in the fully irreversible regime, we find a maximum of the efficiency with values larger than in the linear regime for an optimal choice of the chemical driving force. We show that the corresponding efficiencies can be of the order of 50%. A simple analytic argument allows us to estimate the efficiency in this irreversible regime for small external forces.

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.

Acting on actin: the electric motility assay

We have developed a novel technique which allows one to direct the two dimensional motion of actin filaments on a myosin coated sheet using a weak electric field parallel to the plane of motion. The filament velocity can be increased or decreased, and even reversed, as a function of orientation and strength of the field. PMMA (poly(methylmethacrylate)) gratings, which act as rails for actin, allow one for the first time to explore three quadrants of the force velocity diagram. We discuss effective friction, duty ratio and stall force at different myosin densities. A discontinuity in the velocity force relationship suggests the existence of dynamical phase transition.

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.

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

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.

Serum lecithin: cholesterol acyltransferase activity and HDL2 and HDL3 composition in small for gestational age newborns

The aim of this study was to determine serum lecithin: cholesterol acyltransferase (LCAT) activity in parallel with HDL2 and HDL3 composition in cord sera of small for gestational age (SGA) newborns, and to compare them with those obtained from appropriate for gestational age (AGA) newborns. LCAT activity was assayed by conversion of [3H]cholesterol to labelled cholesteryl ester. HDL2 and HDL3 were separated by ultracentrifugation. Serum cholesteryl ester, apolipoprotein (apo) A-I concentrations and LCAT activity were significantly lower (-47%, -18% and -56%, respectively), whereas serum triglyceride amounts were twofold higher in SGA newborns than in AGA newborns. In SGA newborns, HDL2 and HDL3 levels were low, and HDL3 and HDL2 phospholipid and HDL2-cholesteryl ester contents were diminished. HDL3-apo A-I, A-II, C-III and E values were lower in SGA newborns. In HDL2, apo A-I, A-II and E concentrations were decreased. Therefore, in SGA newborns, the reduced LCAT activity was associated with quantitative and qualitative changes in HDL2 and HDL3 particles.

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.

Rat plasma VLDL composition and concentration and hepatic lipase and lipoprotein lipase activities are impaired during two types of protein malnutrition and unaffected by balanced refeeding

The relationships between VLDL concentrations and composition and changes in hepatic lipase and lipoprotein lipase activities were determined in rats, during the consumption of two low protein diets (2% casein or 5% gluten) (protein malnutrition) for 28 d, followed by the refeeding of a balanced diet for 14 d (15% casein) (refeeding). A control group was fed 15% casein for 42 d. In the control group, total lipolytic activity increased with age (r = 0.83, P < 0.001), whereas in both depleted groups, this activity remained low and stable throughout the period of protein malnutrition. At d 28 of protein malnutrition, plasma total lipolytic activities were significantly reduced in both depleted groups, (P < 0.05); hepatic lipase values represented 23% of the control value and lipoprotein lipase activity was about 11% of the control value. Moreover, lipid supply was even more dramatically diminished by the strong reduction in plasma VLDL concentration in both depleted groups. At d 14 of refeeding, lipoprotein lipase activities remained low in both depleted groups. Hepatic lipase activity was similar in the control and casein groups, but significantly higher in the gluten group. The VLDL composition varied significantly with each type of protein malnutrition and could be attributable to the different low levels of plasma VLDL-apolipoprotein C of rats fed both depleted protein diets, which involve an inhibiting or activating effect on lipoprotein lipase activity. Therefore, our results indicated that both protein-deficient diets investigated may diminish fatty acid supply in the various tissues involved.

Time course of changes in rat serum lecithin-cholesterol acyl-transferase activity and high-density-lipoprotein composition during the consumption of two different low-protein diets followed by a balanced diet

We studied the effects of low-protein diets on high-density-lipoprotein (HDL) composition and checked whether the changes observed were correlated with lecithin-cholesterol acyl-transferase (LCAT) activity. We also studied whether HDL lipid and protein compositions and LCAT activity were modified differently in growing rats during the consumption of two low-protein diets [2% casein (C) and 5% gluten (GI)] for 28 days, followed by the refeeding of a balanced diet containing 15% casein for 14 days. The control group was fed the balanced diet for 42 days. LCAT activity was determined by conversion of 3H-cholesterol into 3H-esterified cholesterol. The consumption of both protein-depleted diets highly decreased LCAT activity. At the end of the period of protein malnutrition, LCAT activity was only 22% and 13% of that of the control group in the C and GI groups, respectively. There was no significant difference between the two depleted diets. At day 3 of refeeding, values of both C and GI groups returned to control values. Despite the reduction in LCAT activity with both types of protein-depleted diets, HDL metabolism was not significantly impaired. This might be partly due to the maintenance of higher apolipoprotein A-I levels. The reduced LCAT activity could be attributable to reduced synthesis of LCAT in the liver during both protein-depleted diets.

In vitro rat pancreatic digestive enzyme activities and raw and heated glandless cottonseed and soybean flours

Higher nitrogen and lipid digestibilities have been obtained with diets containing cottonseed flour rather than soybean flour. To explain these results, in vitro studies were carried out to compare the effects of raw and heated glandless (without gossypol) cottonseed flours versus soybean flours on pancreatic digestive enzyme activities. These effects were compared with those obtained without addition of flour in standard assays. Apparent lipase (lipase colipase dependent) and potential lipase (lipase with saturating amounts of colipase), colipase, phospholipase A2, amylase, trypsin and chymotrypsin activities were measured on specific substrates. Phospholipase A2 and amylase activities were enhanced, while chymotrypsin activity was diminished with both raw and heated flours. Compared with raw and heated soybean flours, raw and heated cottonseed flours promoted higher potential lipase, chymotrypsin, trypsin and lipase activities. Heat treatment of cottonseed flour enhanced apparent lipase, colipase, chymotrypsin, trypsin activities and diminished potential lipase, phospholipase A2 and amylase activities. When soybean flour was heated, apparent lipase, phospholipase A2, chymotrypsin, trypsin and amylase activities were raised while those of potential lipase were decreased. Our findings show that in vitro raw or heated cottonseed flours affect less digestive enzymes than raw or heated soybean flours, apparent lipase activity excepted. Moreover, only chymotrypsin activities were seriously lowered with both flours, especially with raw soybean flour. Hypotheses are suggested to account for the differences in alterations.

Segregation in DNA solutions induced by electric fields

DNA solutions subjected to an electric field exhibit an instability that leads to DNA segregation in aggregates tilted with regard to the field. With the use of epifluorescence videomicroscopy, the evolution of DNA patterns in capillaries as a function of DNA concentration, DNA size, field strength, and field frequency was studied. The field threshold for segregation was decreased when the frequency was lowered or when the DNA molecular weight or concentration was increased. Aggregation is attributed to an electrohydrodynamic instability triggered by the dipole-dipole interaction. This phenomenon explains the failure of earlier attempts to separate large DNA in capillaries.

Pancreatic digestive hydrolase activities in growing rats fed alternately on raw and heated soya-bean flour

The time-course effects of two diets containing raw (RSF) or heated (HSF) soya-bean flour on the digestive enzyme levels in the pancreas and in pancreatic juice were investigated in growing rats fed, alternately, on RSF or HSF diets for two 4-week periods. These values were compared with those obtained in a control group fed on a casein diet. RSF and HSF diets lowered N balance (84.8 (SE 0.9), 82.6 (SE 0.8) and 79.9 (SE 0.8)% with control, HSF and RSF diets respectively, at the third week). However, they increased protease activities compared with the control diet (3-fold for trypsin (EC 3.4.21.4) and chymotrypsin (EC 3.4.21.1) activities in pancreas contents and outputs with the RSF diet; 2-fold for trypsin in pancreas contents and outputs and by 60% for chymotrypsin contents with the HSF diet). The poorer nutritional N utilization might be attributable to soya-bean flour heat-stable (lectins) and heat-labile components (trypsin inhibitors). The decrease in lipid apparent digestibilities in RSF and HSF diets (97.0 (SE 0.8), 91.1 (SE 0.9) and 90.4 (SE 0.7)% with control, RSF and HSF diets at the seventh week) were correlated with a diminution in apparent lipase (EC 3.1.1.3; measured without addition of exogenous colipase), potential lipase (measured with addition of saturated amounts of exogenous colipase) and colipase activities. Compared with control values, gains in potential and apparent lipase outputs were diminished by nearly 40% and gain in colipase outputs by 60% with RSF and HSF diets. These results show clearly that heated or raw soya-bean flours have a significant inhibitory effect on lipase digestive enzyme activities in the pancreas and in its secretion, which might explain impaired lipid digestibility.

Directional motion of brownian particles induced by a periodic asymmetric potential

Structures possessing spatial asymmetry should act as pumps in the presence of dissipation alone, without the need for macroscopic forces or temperature differences to drive vectorial motion. It has been shown theoretically that particles subjected to an asymmetric periodic potential can display net directional motion even if the space-averaged force is zero. Here we demonstrate such behaviour experimentally. We have studied the behaviour of colloidal particles suspended in solution and exposed to a sawtooth dielectric potential which is turned on and off periodically. The particles exhibit net motion with a velocity that depends on their size, suggesting applications in separation processes for objects in the size range 0.1-5 microns--a range that includes biological structures such as viruses, cells and chromosomes. We furthermore point out the analogy between our device and motor protein assemblies.

Dietary protein deficiency affects n-3 and n-6 polyunsaturated fatty acids hepatic storage and very low density lipoprotein transport in rats on different diets

Fatty livers and the similarity between the skin lesions in kwashiorkor and those described in experimental essential fatty acid (EFA) deficiency have led to the hypothesis that protein and EFA deficiencies may both occur in chronic malnutrition. The relationship between serum very low density lipoprotein (VLDL) and hepatic lipid composition was studied after 28 d of protein depletion to determine the interactions between dietary protein levels and EFA availability. Rats were fed purified diets containing 20 or 2% casein and 5% fat as either soybean oil rich in EFA, or salmon oil rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, or hydrogenated coconut oil poor in EFA. Animals were divided into six groups, SOC (20% casein + 5% soybean oil), SOd (2% casein + 5% soybean oil), COC (20% casein + 5% hydrogenated coconut oil), COd (2% casein + 5% hydrogenated coconut oil), SAC (20% casein + 5% salmon oil) and SAd (2% casein + 5% salmon oil). After 28 d, liver steatosis and reduced VLDL-phospholipid contents (P < 0.001) were observed in protein-deficient rats. In protein deficiency, triacylglycerol and phospholipid fatty acid compositions in both liver and VLDL showed a decreased polyunsaturated-to-saturated fatty acid ratio. This ratio was higher with the salmon oil diets and lower with the hydrogenated coconut oil diets. Furthermore, independent of the oil in the diet, protein deficiency decreased linoleic and arachidonic acids in VLDL phospholipids. Conversely, despite decreased proportions of EPA at low protein levels, DHA levels remained higher in rats fed salmon oil diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in fatty acid compositions of total serum and lipoprotein particles, in growing rats given protein-deficient diets with either hydrogenated coconut or salmon oils as fat sources

The present study examines the effects of dietary saturated (hydrogenated coconut oil) and polyunsaturated (salmon oil) fats on the composition and metabolism of lipoproteins in growing rats fed on protein-deficient diets. Four groups of rats were fed on the following diets for 28 d: 200 g casein + 50 g coconut oil (COC)/kg, 20 g casein + 50 g coconut oil (COd)/kg, 200 g casein + 50 g salmon oil (SAC)/kg, 20 g casein + 50 g salmon oil (SAd)/kg. Both protein-deficient groups exhibited low concentrations of protein and triacylglycerol (in serum, very-low-density lipoprotein (VLDL), low-density lipoprotein-high-density lipoprotein, (LDL-HDL1) and HDL2-3), of cholesterol (in LDL-HDL1) and of phospholipids (in VLDL). Furthermore, serum and VLDL cholesterol concentrations were also reduced in the SAd group. Compared with rats given 200 g casein/kg diets, those fed on low-protein diets presented lower linoleic and arachidonic acid levels, in serum phospholipids and a dramatic decrease in the polyunsaturated: saturated fatty acid value. Relative amounts of linoleic and arachidonic acids in phospholipids of VLDL and HDL2-3 were also lowered in the COd group but not in the SAd group. However, proportions of 22:5n-6 and 22:6n-3 in VLDL and HDL2-3 phospholipid fractions were enhanced in the COd and SAd groups respectively. The most affected apolipoproteins (apo) were apo B100 and apo B48 in rats fed on protein-deficient diets, apo AI and apo E in the COd group, and apo AIV in the SAd group. Compared with rats fed hydrogenated coconut oil diets, those fed salmon oil diets had enhanced LDL-HDL1 and HDL2-3 but lower VLDL total apolipoproteins (mainly due to a fall in apo B100 and apo B48). Arachidonic and eicosapentaenoic acids, which are impaired by protein deficiency, are the precursors of prostaglandins, thromboxanes and leukotrienes which are implicated in a number of regulatory processes. Our results demonstrate that protein malnutrition is associated with impaired metabolism of arachidonic and eicosapentaenoic acids. Protein malnutrition and essential fatty acid (EFA) deficiency are characterized by many common clinical features and the link between the two may be an impaired production of eicosanoids, since arachidonic and eicosapentaenoic acids are the precursors of these important metabolic regulators. Because of the apparent involvement of EFA deficiency in the aetiology of protein malnutrition, it may be prudent to include adequate amounts of EFA in diets of infants suffering from kwashiorkor.

[Moraxella (Branhamella) catarrhalis. A common pathogenic agent]

Moraxella (Branhamella) catarrhalis, a commensal organism of the oropharyngeal flora, has been considered a potential pathogen since the early 1970s, mainly causing otitis in infants and exacerbations of chronic bronchitis in the elderly or in immunosuppressed adults. This view was initially based on the isolation of M. catarrhalis during infections: a density of at least 10(7)/ml of sputum, particularly when it exceeds that of other organisms by at least 100-fold, is considered to indicate the responsibility of M. catarrhalis. The pathogenic potential of M. catarrhalis was proven by the increase in specific serum antibodies (total, IgG, IgA) in patients infected by this organism. Given the large proportion (60 percent) of strains that produce beta-lactamase, antibiotic therapy is based on a combination of amoxycillin and clavulanic acid (or another penicillin/beta-lactamase inhibitor combination) or a third-generation cephalosporin; tetracyclines or macrolides can also be used.