Dietary fish protein lowers blood pressure and alters tissue polyunsaturated fatty acid composition in spontaneously hypertensive rats

OBJECTIVE

To investigate the effect of two types of dietary protein on blood pressure, liver fatty acid desaturation and composition, and urine 6-keto-prostaglandin-F (PGF(1alpha)) level, the metabolite of prostacyclin.

METHODS

5-wk-old spontaneously hypertensive rats were fed 20% casein or purified fish protein. The fat source was 5% ISIO oil, which contains 47.9% (omega-6) and 1.7% (omega-3) total polyunsaturated fatty acids. After 2 mo on the diet, systolic blood pressure was reduced with fish protein compared with casein (189.8 +/- 10.5 versus 220.7 +/- 8.7).

RESULTS

Excretion of 6-keto-PGF(1alpha) in urine was negatively correlated with blood pressure. Liver cholesterol and phospholipid concentrations were 1.71- and 1.27-fold lower with fish protein than with casein, respectively. The fish protein diet lowered the 20:4(omega-6) proportion and the ratio of 20:4(omega-6) to 18:2(omega-6) in liver microsomal lipids and phospholipids, which was due to the reduced microsomal Delta6(omega-6) desaturation activity. Dietary protein source did not affect omega-3 fatty acid composition, and this was associated with a similar activation of Delta6(omega-3) desaturation in liver microsomes.

CONCLUSIONS

The present data indicated a significant blood pressure-lowering effect caused by fish protein, rather than by casein, that modified the fatty acid composition of liver phospholipids and liver microsomal total lipids.

Antioxidant status and levels of different vitamins determined by high performance liquid chromatography in diabetic subjects with multiple complications

Plasma vitamin A, C and E levels and erythrocyte antioxidant enzyme activities were investigated in type I and type II diabetic subjects with and without complications, i.e., hypertension, coronary artery disease and renal failure. Reverse phase HPLC was used to quantify vitamin A and E levels. We observed that the vitamin C levels were not significantly different between control and diabetic subjects. However, vitamin A and E levels were significantly lower in type I and type II diabetic subjects compared to controls. Superoxide dismutase (SOD) activity was significantly lower in type II, but not in type I, diabetic patients compared to controls. Interestingly, glutathione reductase and peroxidase activities were diminished in type I, but not in type II, diabetic subjects as compared to controls. Catalase activity was lower in both types of diabetic patients in comparison with their respective controls. Altogether these results suggest that diabetes mellitus may be associated with altered antioxidant status regardless to various complications.

Tissue antioxidant status differs in spontaneously hypertensive rats fed fish protein or casein

The present study was designed to determine whether changes in dietary protein source are related to changes in antioxidant status determined by enzyme activities of catalase, superoxide dismutase (SOD), gluthatione peroxidase (GSH-Px) and gluthatione reductase (GSSG-Red) and lipid peroxidation levels in various tissues. Spontaneously hypertensive rats (SHR; 5 wk old) were fed diets containing 20% casein or fish protein for 2 mo. Feeding the fish protein diet lowered blood pressure and reduced plasma total cholesterol levels and SOD activity in all tissues except muscle compared with the casein diet. Feeding fish protein also enhanced GSH level and GSH-Px activity in liver and heart, accompanied by lower lipid peroxidation. In kidney, however, the lower catalase activity in rats fed fish protein was associated with an enhancement in lipid peroxidation. Plasma and VLDL + LDL lipid peroxidation was unaffected by dietary proteins. In conclusion, the fish protein diet did not play a relevant role in plasma antioxidative defense status but increased it in liver and heart compared with the casein diet. Fish protein attenuated the development of hypertension and also decreased plasma total cholesterol concentration. Thus, it enhances protection against cardiovascular diseases.

Impaired lipoprotein metabolism in obese offspring of streptozotocin-induced diabetic rats

The time course of changes in lipoprotein metabolism of obese offspring of mildly diabetic rats was studied with respect to serum lipoprotein composition as well as LCAT and tissue lipoprotein lipase (LPL) activities. Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin on day 5 of gestation. Control pregnant rats were injected with citrate buffer. At birth, obese pups had higher serum glucose, insulin, and lipoprotein (VLDL, LDL-HDL1, HDL(2-3)) levels than control pups. After 1 mon of life, all of these parameters in obese rats became similar to those of controls. However, LCAT, adipose tissue LPL, and hepatic triacylglycerol lipase activities were high. At 2 mon of age, VLDL-TAG levels were higher in obese females than in controls. By the age of 3 mon, obese offspring had developed insulin resistance with hyperglycemia, hyperinsulinemia, and higher serum lipoprotein concentrations. Indeed, qualitative abnormalities of lipoproteins were seen and were typical of obese and diabetic human beings. Fetal hyperinsulinemia should be considered as a risk factor for later metabolic diseases, including dyslipoproteinemia.

Age-related changes in fatty acids in obese offspring of streptozotocin-induced diabetic rats

OBJECTIVE

The long-term effects of fetal hyperinsulinemia, time course of changes in liver and very-low-density lipoprotein (VLDL) lipid levels and fatty acid compositions were investigated in obese offspring of streptozotocin-induced mildly diabetic rats.

RESEARCH METHODS AND PROCEDURES

Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin on day 5 of gestation. Control pregnant rats were injected with citrate buffer. Liver and VLDL lipids and fatty acids were analyzed in offspring at different ages.

RESULTS

At birth, obese pups had higher VLDL triglyceride levels, saturated fatty acids, and C20:4n-6. They also had lower C18:2n-6 proportions in VLDL triglycerides, phospholipids, and cholesteryl esters than controls pups. In 1-month-old male and female obese rats, VLDL and liver lipid amounts were similar to those in their respective controls; however, high levels of C18:2n-6 and C20:4n-6 were noted in liver and VLDL lipids. At the age of 2 months, liver and VLDL triglyceride levels were higher in obese females than in control females. Fatty acid abnormalities seen in obese rats included low C18:3n-3 and high C22:6n-3 proportions in liver triglycerides and phospholipids. At the age of 3 months, obese rats, both males and females, compared with control animals, had higher VLDL and hepatic lipids with reduced C20:4n-6 levels and polyunsaturated/saturated fatty acids ratios in hepatic and VLDL triglycerides and phospholipids.

DISCUSSION

Fetal obesity, associated with alterations in VLDL lipid fatty acid composition, represents an important risk factor for adult obesity and diabetes.

Bidirectional cooperative motion of molecular motors

Recently, in a beautiful set of experiments, it has been shown that a Ncd mutant, NK11, which lacks directionality in its individual motion, was able to exhibit a new kind of directed motion in motility assays (Endow, S. A. & Higuchi, H. (2000) Nature (London) 406, 913-916): the filaments keep a given velocity for a while and then suddenly move in the opposite direction with similar velocity. We show that these observations nicely illustrate the concept of dynamic transitions in motor collections introduced earlier in the case of an infinite number of motors. We investigate the experimentally relevant case of a finite number of motors both when directionality is present (kinesins, myosins, Ncd) and absent (NK11). Using a symmetric two-state model, we demonstrate that bidirectional motion is the signature of a dynamic transition that results from the collective behavior of many motors acting on the same filament. For motors exhibiting directional bias individually, an asymmetric two-state model is appropriate. In that case, dynamic transitions exist for motor collections in the presence of an external force. We give predictions for the dependence of motion on ATP concentration, external forces, and the number of motors involved. In particular, we show that the reversal time grows exponentially with the number of motors per filament.

Active membrane fluctuations studied by micropipet aspiration

We present a detailed analysis of the micropipet experiments recently reported by J-B. Manneville et al., [Phys. Rev. Lett. 82, 4356 (1999)], including a derivation of the expected behavior of the membrane tension as a function of the areal strain in the case of an active membrane, i.e., containing a nonequilibrium noise source. We give a general expression, which takes into account the effect of active centers both directly on the membrane and on the embedding fluid dynamics, keeping track of the coupling between the density of active centers and the membrane curvature. The data of the micropipet experiments are well reproduced by our expressions. In particular, we show that a natural choice of the parameters quantifying the strength of the active noise explains both the large amplitude of the observed effects and its remarkable insensitivity to the active-center density in the investigated range.

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.

Endoscopic treatment of urinary incontinence: long-term evaluation of the results

PURPOSE

We report on the use of polydimethylsiloxane for endoscopic treatment of urinary incontinence in children with neurogenic bladder and discuss our results to determine optimal criteria for patient selection.

MATERIALS AND METHODS

A total of 44 children (19 males) have been treated endoscopically for urinary incontinence since 1995. Etiology was spina bifida in 35 cases. Previous surgery had been performed on 24 patients, including bladder neck reconstruction with (17) or without bladder augmentation. Mean patient age at injection was 13 years (range 7 to 17). A single transurethral injection was given in 23 cases, 2 in 17 and 3 or more in 4. Mean volume at each injection was 3.5 cc and for each patient the total volume injected was 5.7 cc. Mean delay between 2 injections was 6 months (range 3 to 15).

RESULTS

Followup ranged from 6 to 53 months (median 28). Of the patients 15 (34%) are dry (continent greater than 4 hours, no urinary pad during the day), 11 (25%) are improved (continent 2 to 3 hours, occasional pad) and 18 had poor results. In the entire series only gender and preoperative hyperactivity influenced the results, as the best results were achieved in females with a stable bladder (44% of girls versus 21% of boys were cured). Good results persisted at 12-month followup in patients treated with only 1 injection (until 36 months for older patients) and after the last of 2 injections. Of the patients treated with 3 or more injections 1 was dry at 12-month followup and treatment failed in 3.

CONCLUSIONS

Injection of polydimethylsiloxane at the bladder neck achieved continence in 34% of neurogenic bladder cases. Results were better in girls with a stable bladder. Results deteriorated in the first 12 months of followup. No more than 3 injections are advised if a satisfactory result is not achieved.

Endoscopic treatment of urinary incontinence: long-term evaluation of the results

PURPOSE

We report on the use of polydimethylsiloxane for endoscopic treatment of urinary incontinence in children with neurogenic bladder and discuss our results to determine optimal criteria for patient selection.

MATERIALS AND METHODS

A total of 44 children (19 males) have been treated endoscopically for urinary incontinence since 1995. Etiology was spina bifida in 35 cases. Previous surgery had been performed on 24 patients, including bladder neck reconstruction with (17) or without bladder augmentation. Mean patient age at injection was 13 years (range 7 to 17). A single transurethral injection was given in 23 cases, 2 in 17 and 3 or more in 4. Mean volume at each injection was 3.5 cc and for each patient the total volume injected was 5.7 cc. Mean delay between 2 injections was 6 months (range 3 to 15).

RESULTS

Followup ranged from 6 to 53 months (median 28). Of the patients 15 (34%) are dry (continent greater than 4 hours, no urinary pad during the day), 11 (25%) are improved (continent 2 to 3 hours, occasional pad) and 18 had poor results. In the entire series only gender and preoperative hyperactivity influenced the results, as the best results were achieved in females with a stable bladder (44% of girls versus 21% of boys were cured). Good results persisted at 12-month followup in patients treated with only 1 injection (until 36 months for older patients) and after the last of 2 injections. Of the patients treated with 3 or more injections 1 was dry at 12-month followup and treatment failed in 3.

CONCLUSIONS

Injection of polydimethylsiloxane at the bladder neck achieved continence in 34% of neurogenic bladder cases. Results were better in girls with a stable bladder. Results deteriorated in the first 12 months of followup. No more than 3 injections are advised if a satisfactory result is not achieved.

[Correlation between Gleason score of prostatic biopsies and the one of the radical prostatectomy specimen]

The Gleason score obtained on prostatic biopsies is an essential element in the treatment decision for localized prostate cancer. The objective of this study was to evaluate the correlation between the biopsy Gleason score and the definitive Gleason score and to propose a classification into 3 groups in order to improve this correlation.

MATERIAL AND METHODS

One hundred radical prostatectomies were performed between 1995 and 1998. Eighty four of these patients underwent 6 biopsies. The Gleason score of the biopsies and operative specimens were compared. The concordance between the biopsy Gleason score and the operative specimen Gleason score was initially analysed score by score. The concordance was then established according to three groups, well differentiated tumours (score 2-4), moderately differentiated tumours (score 5-7), poorly differentiated tumours (score 8-10).

RESULTS

The concordance between the biopsy Gleason score and the operative specimen Gleason score was perfect in only 37% of cases. A 1-point difference of the score was observed in 35.7% of cases and a 2-point or greater difference was observed in 27.3% of cases. By classifying patients into 3 groups, the concordance increased from 37% to 72.6%.

CONCLUSION

The classification of patients into three distinct groups (well, moderately and poorly differentiated tumours) increases the concordance between the biopsy Gleason score and the definitive Gleason score. However, the limitations of the biopsy Gleason score must be kept in mind, particularly in the case of low-grade tumours.

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.

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.

An elastic analysis of Listeria monocytogenes propulsion

The bacterium Listeria monocytogenes uses the energy of the actin polymerization to propel itself through infected tissues. In steady state, it continuously adds new polymerized filaments to its surface, pushing on its tail, which is made from previously cross-linked actin filaments. In this paper we introduce an elastic model to describe how the addition of actin filaments to the tail results in the propulsive force on the bacterium. Filament growth on the bacterial surface produces stresses that are relieved at the back of the bacterium as it moves forward. The model leads to a natural competition between growth from the sides and growth from the back of the bacterium, with different velocities and strengths for each. This competition can lead to the periodic motion observed in a Listeria mutant.

Measurement of the elasticity of the actin tail of Listeria monocytogenes

We report biophysical experiments performed on the bacterium Listeria monocytogenes, a model system to study actin-based motility. Using optical tweezers and electrophoresis experiments, we find that the bacterium is firmly attached to its tail, and we demonstrate that the tail responds as an elastic gel when deformed. We have measured its elastic modulus at a value of 10(3)-10(4) Pa, which is 10 times higher than the rigidity of the eukaryotic cytoplasm. These results demonstrate that the bacterium and its tail form a very robust system, consistent with the steadyness of the motion observed in vivo. We propose an elastic model for the propulsion mechanism which takes into account the connection and thus the interaction between the actin filaments. It provides a generic description of the various aspects of actin-tail based movements.

Shape transitions of giant liposomes induced by an anisotropic spontaneous curvature

We explore how a magnetic field breaks the symmetry of an initially spherical giant liposome filled with a magnetic colloid. The condition of rotational symmetry along the field axis leads either to a prolate or to an oblate ellipsoid. We demonstrate that an electrostatic interaction between the nanoparticles and the membrane triggers the shape transition.

[Epidermoid cyst of the testis. Conservative surgery in 3 cases]

The authors report 3 cases of epidermoid cyst of the testis. Clinical, laboratory and ultrasound data were relatively nonspecific. Precise histological criteria were defined by PRICE in 1969. The diagnosis is based on frozen section examination after transnnguinal testicular exploration. The authors describe the most conservative therapeutic approach for a constantly benign testicular tumour.

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.

Nonequilibrium fluctuations, traveling waves, and instabilities in active membranes

The stability of a flexible fluid membrane containing a distribution of mobile, active proteins (e.g., proton pumps) is shown to depend on the structure and functional asymmetry of the proteins. A stable active membrane is in a nonequilibrium steady state with height fluctuations whose statistical properties are governed by the protein activity. Disturbances are predicted to travel as waves at sufficiently long wavelength, with speed set by the normal velocity of the pumps. The unstable case involves a spontaneous, pump-driven undulation of the membrane, with clumping of the proteins in regions of high activity.

Auditory sensitivity provided by self-tuned critical oscillations of hair cells

We introduce the concept of self-tuned criticality as a general mechanism for signal detection in sensory systems. In the case of hearing, we argue that active amplification of faint sounds is provided by a dynamical system that is maintained at the threshold of an oscillatory instability. This concept can account for the exquisite sensitivity of the auditory system and its wide dynamic range as well as its capacity to respond selectively to different frequencies. A specific model of sound detection by the hair cells of the inner ear is discussed. We show that a collection of motor proteins within a hair bundle can generate oscillations at a frequency that depends on the elastic properties of the bundle. Simple variation of bundle geometry gives rise to hair cells with characteristic frequencies that span the range of audibility. Tension-gated transduction channels, which primarily serve to detect the motion of a hair bundle, also tune each cell by admitting ions that regulate the motor protein activity. By controlling the bundle's propensity to oscillate, this feedback automatically maintains the system in the operating regime where it is most sensitive to sinusoidal stimuli. The model explains how hair cells can detect sounds that carry less energy than the background noise.

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.

Growing an actin gel on spherical surfaces

Inspired by the motility of the bacteria Listeria monocytogenes, we have experimentally studied the growth of an actin gel around spherical beads grafted with ActA, a protein known to be the promoter of bacteria movement. On ActA-grafted beads F-actin is formed in a spherical manner, whereas on the bacteria a "comet-like" tail of F-actin is produced. We show experimentally that the stationary thickness of the gel depends on the radius of the beads. Moreover, the actin gel is not formed if the ActA surface density is too low. To interpret our results, we propose a theoretical model to explain how the mechanical stress (due to spherical geometry) limits the growth of the actin gel. Our model also takes into account treadmilling of actin. We deduce from our work that the force exerted by the actin gel on the bacteria is of the order of 10 pN. Finally, we estimate from our theoretical model possible conditions for developing actin comet tails.

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.