Biomedical subjects

Claude Gharib

Publications and source records attributed to Claude Gharib.

At least 19 recordsLinked to original sources

PubMed2006

Effect of physical inactivity on the oxidation of saturated and monounsaturated dietary Fatty acids: results of a randomized trial.

OBJECTIVES: Changes in the way dietary fat is metabolized can be considered causative in obesity. The role of sedentary behavior in this defect has not been determined. We hypothesized that physical inactivity partitions dietary fats toward storage and that a resistance exercise training program mitigates storage. DESIGN: We used bed rest, with randomization to resistance training, as a model of physical inactivity. SETTING: The trial took place at the Space Clinic (Toulouse, France). PARTICIPANTS: A total of 18 healthy male volunteers, of mean age +/- standard deviation 32.6 +/- 4.0 y and body mass index 23.6 +/- 0.7 kg/m(2), were enrolled. INTERVENTIONS: An initial 15 d of baseline data collection were followed by 3 mo of strict bed-rest alone (control group, n = 9) or with the addition of supine resistance exercise training every 3 d (exercise group, n = 9). OUTCOME MEASURES: Oxidation of labeled [d(31)]palmitate (the main saturated fatty acid of human diet) and [1-(13)C]oleate (the main monounsaturated fatty acid), body composition, net substrate use, and plasma hormones and metabolites were measured. RESULTS: Between-group comparisons showed that exercise training did not affect oxidation of both oleate (mean difference 5.6%; 95% confidence interval [95% CI], -3.3% to 14.5%; p = 0.20) and palmitate (mean difference -0.2%; 95% CI, -4.1% to 3.6%; p = 0.89). Within-group comparisons, however, showed that inactivity changed oxidation of palmitate in the control group by -11.0% (95% CI, -19.0% to -2.9%; p = 0.01) and in the exercise group by -11.3% (95% CI, -18.4% to -4.2%; p = 0.008). In contrast, bed rest did not significantly affect oleate oxidation within groups. In the control group, the mean difference in oleate oxidation was 3.2% (95% CI, -4.2% to 10.5%; p = 0.34) and 6.8% (95% CI, -1.2% to 14.7%; p = 0.08) in the exercise group. CONCLUSIONS: Independent of changes in energy balance (intake and/or output), physical inactivity decreased the oxidation of saturated but not monounsaturated dietary fat. The effect is apparently not compensated by resistance exercise training. These results suggest that Mediterranean diets should be recommended in sedentary subjects and recumbent patients.

Journal Article↗

PubMed2005

Blood volume measurement: The comparison of pulse dye densitometry and Dill and Costill's methods.

In many clinical situations, it is crucial to determine circulating blood volume (BV) easily and to repeat this measurement. The Dye DensitoGram Analyzer (DDG, Nihon Kohden Corp) measures semi-automatically BV, using an injection of IndoCyanine Green (ICG, 10 mg), and avoiding intermittent blood samples. The DDG was used during a 90-day microgravity simulation by Head-Down-Tilt bed rest (HDT) to measure BV and compared with the calculation of the plasma volume (PV) variations according to Dill and Costill's formula (DC). Seventeen healthy volunteers were included: 8 control subjects (Co) and 9 subjects submitted to a resistive exercise counter-measure (CM). Measurements were performed, one day before HDT, on days 3 and 90 of HDT and on day 9 after HDT. A double measurement of the BV was performed to assess the repeatability of this method. On the last day of HDT a significant decrease (p < 0.05) in the PV was noted with the DDG (Co: -12.3+/-5.7%, CM: -9.0+/-5.3%) and DC; (Co: -4.7+/-1.8%, CM: -6.8+/-2.5%). A good repeatability of the technique was shown with a low intrasubjects coefficient of variation (4.95+/-0.95%) and an acceptable intersubjects coefficient of variation (15.30+/-1.13%). No correlation was noted between DDG and DC (r2 = 0.27). The DDG gives a good repeatability, not affected by the microgravity exposure. Thanks to its capacity to measure accurately the BV within 7-10 min, this device presents major advantages for clinical use and research purpose.

Adult↗

PubMed2005

Skinfold thickness versus isotope dilution for body fat assessment during simulated microgravity: results from three bed-rest campaigns in men and women with and without countermeasures.

Because body composition is altered during head-down bed rest (HDBR), body mass can not be used as an index of energy balance. Consequently diet allowances should not be based on body mass evolution but on fat mass changes. Though criticized, skinfold thickness (ST) is the costless, easiest and fastest method to use for such an objective. The aim of this study was to compare the percentage of body fat (%BF) estimated by ST with the isotope dilution of H2 18O. We compiled data from three HDBR campaigns, one on women (n=8) in November 1998 and two on the same men (n=8) in December 1997 (without countermeasure) and January 1998 (with thigh-cuffs countermeasure), according to a crossover design. Body composition was assessed before and after 6 days of HDBR. %BF was derived from the biceps, triceps, sub-scapular and sup-iliac ST according to Durnin and Wormersly (1974). Fat-free mass was measured on the same day by H2 18O dilution and fat mass was calculated by the difference with body mass and expressed as a percentage. Based on precision tests, the minimum measurable change by ST was 1.1%BF for single measurement point. Both intercepts (F (4,30)=0.89, P=0.45) and slopes (F (4,30)=0.74; P=0.57) of the ST versus dilution relationships were not affected by the periods (December vs January), experimental conditions (control vs HDBR vs HDBR + thigh cuffs) or sex allowing the derivation of a common relationship %BF(st)=0.94 x %BF(dil) (F (1,47)=97.9, P<0.0001; non-significant intercept excluded) with a bias between methods of -1.7+/-2.0 %BF (95% CI: -5.8, 2.4 %BF). ST can be used to measure %BF during HDBR provided great care is placed on training and changes are higher than 1.1 %BF. If the method can be applied for in-flight energy balance monitoring given the high observed energy deficit, a tight monitoring of the individual nutritional status as needed during simulation appears, however, dubious based on this solely method.

Adiposity↗

PubMed2005

[Regulation of blood volume during weightlessness simulation of long duration].

To study the effects of microgravity on the mechanisms involved in the regulation of body hydrous status, total body water (TBW), plasma volume (PV), and its main regulating hormones (plasma renin, aldosterone, atrial natriuretic peptide (ANP), anti-diuretic hormone (ADH)) were determined, by isotopic dilution, Dill and Costill's formula, and radio-immunologic dosages, in 9 male subjects submitted to a 90-d head-down bed rest (HDBR). ADH was determined in 24 h urinary collection as well as osmolality, sodium, and potassium. Body mass decreased (-2.8 +/- 0.8 kg) as well as TBW(-7.2% +/- 0.9%, i.e., -2.6 +/- 0.7 kg) and PV (-4.7% +/- 1.8%). Renin and aldosterone were enhanced (+109.0% +/- 15.4% and +87.2% +/- 38.9%, respectively). Simultaneously, we observed a decrease in ANP (-33.2% +/- 20.4%). Other variables, including ADH, were not affected by HDBR. Body mass and TBW decrease (and consequently lean body mass) are associated with muscle atrophy. Renin, aldostrerone, and ANP modifications are well explained by the decrease in PV, which was not enough to induce ADH changes. It suggests that in man, the main regulatory factor for ADH secretion is osmolality, when PV is modestly and progressively decreased without arterial pressure modification, which was the case in the present protocol.

Adult↗

PubMed2004

Calf venous volume during stand-test after a 90-day bed-rest study with or without exercise countermeasure.

The objectives to determine both the contribution to orthostatic intolerance (OI) of calf venous volume during a stand-test, and the effects of a combined eccentric-concentric resistance exercise countermeasure on both vein response to orthostatic test and OI, after 90-day head-down tilt bed-rest (HDT). The subjects consisted of a control group (Co-gr, n = 9) and an exercise countermeasure group (CM-gr, n = 9). Calf volume and vein cross-sectional area (CSA) were assessed by plethysmography and echography during pre- and post-HDT stand-tests. From supine to standing (post-HDT), the tibial and gastrocnemius vein CSA increased significantly in intolerant subjects (tibial vein, +122% from pre-HDT; gastrocnemius veins, +145%; P < 0.05) whereas it did not in tolerant subjects. Intolerant subjects tended to have a higher increase in calf filling volume than tolerant subjects, in both sitting and standing positions. The countermeasure did not reduce OI. Absolute calf volume decreased similarly in both groups. Tibial and gastrocnemius vein CSA at rest did not change during HDT in either group. During the post-HDT stand-test, the calf filling volume increased more in the CM-gr than in the Co-gr both in the sitting (+1.3 +/- 5.1%, vs. -7.3 +/- 4.3%; P < 0.05) and the standing positions (+56.1 +/- 23.7% vs. +1.6 +/- 9.6%; P < 0.05). The volume ejected by the muscle venous pump increased only in the CM-gr (+38.3 +/- 21.8%). This study showed that intolerant subjects had a higher increase in vein CSA in the standing position and a tendency to present a higher calf filling volume in the sitting and standing positions. It also showed that a combined eccentric-concentric resistance exercise countermeasure had no effects on either post-HDT OI or on the venous parameters related to it.

Adult↗

PubMed2004

Does resistance exercise prevent body fluid changes after a 90-day bed rest?

Although various exercise regimens are commonly used as countermeasures to reduce the cardiovascular deconditioning induced by microgravity, the underlying mechanisms are not well understood. In this study we aimed to test whether lower limb resistance exercise with flywheel technology can prevent the fluid homeostasis alterations induced by 90-day head-down tilt bed-rest (HDT), and thus improve orthostatic tolerance. Total body water (TBW, measured by isotope dilution) and plasma volume (PV, calculated from the haemoglobin and the haematocrit) were measured in a control group (Co, n=9) and a countermeasure group (CM, n=9). Simultaneously, plasma atrial natriuretic peptide (ANP), renin (AR), and aldosterone (Aldo), as well as urinary anti-diuretic hormone (ADH), were measured. Orthostatic tolerance was evaluated with a 10 min +80 degrees tilt-test the first day of recovery. After HDT, both groups showed a comparable decrease in orthostatic tolerance [8.2 (0.9) min, Co; 8.0 (0.7) min, CM], PV [-4.7 (1.8)%, Co; -6.2 (2.5)%, CM, P<0.05] and TBW [-6.3 (5.4)%, Co; -3.7 (2.1)%, CM, P<0.05]. AR [97.4 (22.0)%, Co; 117.3 (26.4)%, CM] and Aldo [111.3 (58.4)%, Co; 100.6 (52.0)%, CM] increased significantly in both groups but the countermeasures produced no noticeable effects [data are expressed as mean (SE)]. The drop in ANP was also similar in both groups [-42.0 (15.2)%, Co; -51.1 (27.7)% for the CM]. Surprisingly, urinary ADH declined similarly in both groups during the basal data control period [-25.3 (5.2)%, Co; -26.1 (9.6)%, CM) and was sustained at this level during the 90-day HDT. These results show that, under the conditions described, the flywheel exercise device failed to improve characteristic manifestations of cardiovascular deconditioning and suggest that more frequent and powerful exercise, associated with another device (e.g. LBNP) might be a better countermeasure.

Adult↗

PubMed2004

[Effect of dehydration on nitric oxide, corticotropic and vasopressinergic axis in rat].

Effect of dehydration on nitric oxide, corticotropic and vasopressinergic axis in rat. The purpose of our work is to study, in the male 'Wistar' rat, the effects of a chronic dehydration, by deprivation of water for three days out of four, during four repeated cycles, on the evolution of certain blood variables, on the activities of both corticotropic and vasopressinergic axis and on the synthesis of nitric oxide. The chronic dehydration causes a considerable reduction of the body weight, an activation of the vasopressinergic axis and an increase in the circulating rates of the nitrates/nitrites, which represent the final metabolites of the reaction of oxidation of nitric oxide. The pituitary-adrenal axis is not statistically affected by the chronic dehydration. This seems to be in favour of a possible adaptation of corticotropic axis to chronic water deprivation. The activation of synthesis of nitric oxide shows its implication in the regulation of the water balance and its buffer effect on vasoconstriction and hypertension induced by water stress.

Adrenocorticotropic Hormone↗

PubMed2004

[Age-related metabolic development in rats: insulin's role].

The aim of our work was to study the developmental changes in plasma and hepatic concentrations of carbohydrates, lipids, and proteins in "Wistar" rats between prepartum day 1 (fetus considered J-1) and postpartum day 133 (adult considered j+133). In addition, the evolution of insulinemia has been examined. The 21 day aged fetus (j-1), as compared to the adult (j+133) showed a lower glycemia, a higher stock of hepatic glycogen, lower rates of lipids and proteins in the plasma and in the liver. The fetal insulinemia was significantly higher than adult's. After the delivrance we have attended to an increase of the glycemia and a very marked depletion of the glycogenic stock in the liver. The plasma and hepatic lipids and proteins rose after birth. The insulinemia fell considerably and reached the lowest level. Between the 14th and 30th day of the postnatal life, a restoration of the stock of the hepatic glycogen, a normal glycemia, an elevation of the plasma and hepatic rates of proteins, and a decrease of the lipidic levels in plasma and liver were recorded. In addition the concentration of insulin increased during this period. All these values remained steady during the adult stage. We conclude that the development of rats is accompanied with several metabolic and hormonal changes. These are particularly marked at birth and weaning.

Aging↗

PubMed2003

Hormonal changes during 17 days of head-down bed-rest.

We investigated in six men the impact of 17 days of head-down bed rest (HDBR) on the daily rhythms of the hormones involved in hydroelectrolytic regulation. This HDBR study was designed to mimic a real space flight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of Growth Hormone (GH), Cortisol, 6 Sulfatoxymelatonin, Normetadrenaline (NMN) and Metadrenaline (NM) was determined. A decrease in urinary cortisol excretion during the night of HDBR was noted. For GH, a rhythm was found before and during HDBR. The rhythm of melatonin, evaluated with the urine excretion of 6 Sulfatoxymelatonin (aMT6S), the main hepatic metabolite, persisted throughout the experiment without any modification to the level of phase. A decrease during the night was noted for normetadrenaline urinary derivates, but only during the HDBR.

Adult↗

PubMed2003

Changes in intraocular pressure during prolonged (7-day) head-down tilt bedrest.

PURPOSE: To determine the change in intraocular pressure (IOP) due to postural changes in young healthy volunteers. MATERIALS AND METHODS: Intraocular pressure was measured using a calibrated Pulsair noncontact tonometer in both eyes of 25 female volunteers in a sitting position and after 1, 3, and 10 minutes in a supine position. In the second part of the experiment (a 7-day -6 degrees head-down tilt [HDT]), IOP (at 8 am, 12 am and 6 pm) and corneal thickness (12 am) were monitored in 8 female volunteers before, during, and after the HDT period. Blood pressure, hematocrit, plasma volume and osmolality, and plasma catecholamines concentrations were also measured. RESULTS: Intraocular pressure was significantly higher in the supine position (16.1 +/- 3.6 mm Hg) than in the sitting position, with a mean pressure difference of 2.23 +/- 2.9 mm Hg after 1 minute, 0.9 +/- 3 mm Hg after 3 minutes, and 1.9 +/- 3.8 mm Hg after 10 minutes in a supine position (P < 0.001). During the period of HDT, IOP values decreased significantly on the fifth day (13.3 +/- 1.6 mm Hg, P = 0.03) and the seventh day (12.7 +/- 1.7 mm Hg, P = 0.02) when compared with IOP in the supine position (14.26 +/- 2 mm Hg). The corneal thickness increased significantly (P < 0.0001) at day 5 (549.25 +/- 48.7 microm) and day 7 (540.31 +/- 46.9 microm) compared with baseline (532.45 +/- 38.6 microm). Two days after the end of the HDT bedrest, the mean supine IOP significantly increased (14.1 +/- 1.8 mm Hg, P = 0.003) and corneal thickness was similar to that found at baseline. The mean decrease of IOP was positively correlated with that of the plasma volume (-10%, r = 0.61, P = 0.02) and negatively correlated with the mean rise of hematocrit (r = -0.5, P = 0.07), variables that are considered to be indirect measures of plasma dehydration. CONCLUSIONS: During a 7-day HDT bedrest experiment in healthy women, eyes seemed to compensate the moderate rise of IOP described between a sitting and a supine position, and exhibited a slight and progressive average decrease of 1.3 mm Hg. These physiological modifications could be related to an ocular dehydration or to systemic cardiovascular and hormonal variations during bedrest.

Adult↗

PubMed2002

Orthostatic tolerance and spontaneous baroreflex sensitivity in men versus women after 7 days of head-down bed rest.

Many factors are involved in the development of orthostatic intolerance after real or simulated weightlessness. The aim of our study was to compare the effects of 7-day head-down bed rest (HDBR) in eight women and eight men on the spontaneous baroreflex sensitivity (standard spectral method and new time-frequency algorithm) during lower body negative pressure (LBNP) tests. Results obtained before HDBR have shown in women, compared to men, higher heart rate, lower blood pressure, higher parasympathetic modulation at rest and greater decrease in baroreflex sensitivity with greater increase in sympathetic activity during LBNP. After HDBR, we observed in both men and women a dramatic decrease in orthostatic tolerance (7.0 min at R + 1 vs. 10.0 min, p<0.05, at BDC-1 in men; 5.4 vs. 9.0 min, p<0.05, in women) together with a decrease in plasma volume (-9.1 +/- 0.9% in men, -9.5 +/- 1.4% in women) and in spontaneous baroreflex sensitivity without gender effect. After HDBR, at the highest level of LBNP, diastolic blood pressure increased in men (+5.6 +/- 1.3 mm Hg) and decreased in women (-1.0 +/- 2.7 mm Hg) with a gender difference (p<0.05). This result suggests impaired vasoconstriction in women after HDBR. Neither endocrine response nor alterations to the cardiac baroreflex can explain gender differences in orthostatic tolerance after HDBR as reported by previous studies. Further studies need to be conducted in order to obtain a more precise analysis of gender difference in arteriolar vasoconstriction after HDBR. The time frequency method we developed to study changes in spontaneous baroreflex might be applied to the analysis of LBNP tests.

Adult↗

PubMed2002

A preservation solution with polyethylene glycol and calcium: a possible multiorgan liquid.

The addition of polyethylene glycol (PEG) to hepatocyte storage medium is known to decrease lipid peroxidation and swelling and to protect the cell cytoskeleton from cold. We therefore decided to investigate the effect of substituting PEG for hydroxyethyl starch (HES) in an extracellular-like UW solution, with and without Ca++, on rat liver preservation. Isolated perfused rat livers were used to assess graft injury after 24h of cold storage. Four groups of preserved livers ( n=6 for each group) were compared to controls (non preserved livers, n=11). For this purpose, Belzer solution (K+-UW, group 1) was stepwise modified. Group 2 (Na+-UW) was treated with the same liquid, however with inverted concentrations of Na+ and K+. Group 3 was preserved in the first experimental solution (EPS-1) with Ca++ (0.5mM) added to the Na+-UW solution. In the EPS-2 (group 4), PEG-35 (0.03mM) was substituted for HES. The last group, EPS-3 (group 5) was treated with the same compounds as EPS-2, but without Ca++. After 24h of cold storage and 120min normothermic reperfusion, there was no statistical difference in transaminases (ALT and AST) release between the control and the Na+-UW groups. Furthermore, rat livers preserved in Na+-UW solution released less ( P<0.05) ALT and AST and excreted more ( P<0.05) indocyanine green (ICG) than livers preserved in K+-UW solution. The addition of 0.5mM Ca++ to Na+-UW solution (EPS-1) dramatically increased ( P<0.05) parenchymal (ALT, AST) and non parenchymal (creatine kinase-BB) cellular injury. The substitution of PEG (0.03mM) for HES (EPS-2) reduced ( P<0.05) membrane injuries due to Ca++ while bile flow was statistically increased ( P<0.05). Finally, the omission of Ca++ from EPS-2, that is EPS-3, has no statistically significant effect on the studied parameters. PEG effectively protected the rat liver grafts from the onset of hypothermic ischemia-reperfusion and Ca++ damages and thus may be a valuable additive to preservation solutions.

Animals↗

PubMed2002

Heart rate variability after prolonged spaceflights.

Astronauts returning from spaceflight often experience post-flight orthostatic intolerance. This study was designed to determine whether cosmonauts with post-flight syncope could be distinguished from those with no post-flight syncope. The autonomic function was determined in a group of ten subjects, with no previous history of syncope, during a stand test before and after a long-term spaceflight (90 to 198 days). Heart rate (HR) and systolic blood pressure (SBP) were measured beat-by-beat, pre- and post-flight and the spontaneous baroreflex sensitivity and HR variability were studied. Individuals were categorized according to their ability to remain standing for 5 min the day after landing. Three of the ten cosmonauts failed to finish the standing test performed the day after landing (nonfinishers). The spontaneous baroreflex slope was reduced in both groups after the spaceflight. The non-finisher group had a lower SBP (P < 0.05) at rest in pre-flight tests than the group that completed the test (finisher group). The non-finisher group also had higher indicators of parasympathetic activity when supine, both pre- and post-flight, but this difference disappeared with standing. At the end of the stand test, SBP and HR were lower in non-finisher cosmonauts than the finishers, while HR did not increase compared to early measurements in the stand test of the finisher group. These results suggest an impairment in autonomic control of HR, which might contribute to the fainting response.

Adult↗

PubMed2002

Energy expenditure and blood flows in thermoregulatory organs during microgravity simulation in rat. Emphasis on the importance of the control group.

Rat tail suspension is commonly used to mimic human physiology in space. However, energy metabolism adaptation and related autonomic responses are unknown. To give new insights in energy homeostasis, we determined total energy expenditure (TEE) and blood flow redistribution in thermoregulatory organs during suspension using two control groups of animals widely accepted in the literature: the individually housed (isolated) and restraint rats (horizontally attached to the suspension device). Rats (n=33) were randomly assigned during 14-days to three experimental groups: isolated, suspended, or attached. TEE was assessed by a doubly labeled water method throughout the 14 days, and regional blood flow by radiolabeled microsphere procedure at the end of the protocol. Attachment vs. suspension resulted in a significant decrease in TEE (25%), skin (54%), adrenal (55%) and kidney (42%) blood flows, cardiac index (33%), and plasma corticosterone (50%), whereas total peripheral resistances increased (50%). Isolation vs. attachment triggered an inverse response, of similar amplitude, for all above variables. By comparing isolation and suspension, no overall effect was observed. The striking conclusion of this study is that no clear conclusion can be drawn. The choice of the isolated or attached animals as control profoundly influences the outcome results regarding the effects of simulated weightlessness. Further studies are needed but we favor the attached group as the true control since, from a theoretical point of view, a suspended rat is attached plus suspended. In such conditions, TEE decreases to the same extent in rat and humans during simulated microgravity. When reviewing published experiments, we recommend special attention to the control group used rather than on the effects of suspension as compared to an undefined control.

Animals↗

PubMed2002

Long-term sodium balance in humans in a terrestrial space station simulation study.

BACKGROUND: Sodium accumulation has been considered to take place in the extracellular space, leading to water retention and weight gain. This traditional view has been questioned by recent studies that showed sodium accumulation in humans without expansion of the extracellular volume. We investigated sodium balance and its impact on body weight (BW) during a long-term balance study. METHODS: Three healthy subjects were confined to a terrestrial MIR simulator for 135 days under conditions simulating a long-term spaceflight. During the entire isolation period, we meticulously measured daily sodium balance and its contribution to BW. RESULTS: During the study period, subjects accumulated between 2,973 and 7,324 mmol of sodium and gained between 5.1 and 9.3 kg in weight. In all subjects, there was a positive correlation between changes in total-body sodium (DeltaTBS) content and BW, reflecting sodium-associated volume expansion. However, toward the end of isolation, sodium gain exceeded weight gain, suggesting that sodium accumulated in an osmotically inactive form. Especially at the onset of the experiment, two subjects showed inverse correlations between DeltaTBS and BW. CONCLUSION: The finding of sodium gain without weight gain is in contradiction to the widely accepted theory that changes in TBS levels are accompanied by changes in extracellular volume. We suggest the existence of a sodium reservoir with the ability to store significant amounts of sodium in an osmotically inactive form. This reservoir might be located in bone, dense connective tissue, or cartilage.

Adult↗

PubMed2002

Spontaneous baroreflex sensitivity: toward an ideal index of cardiovascular risk in hypertension?

OBJECTIVE: Estimating the risk entailed by classical risk factors like blood pressure (BP) or serum cholesterol may be difficult because of their variability and the often unknown duration of exposure. Having variables integrating the impact of those classical risk factors on the cardiovascular system would probably aid the prediction of cardiovascular events. The present study aimed at determining whether cardiac baroreflex sensitivity (BRS), correlates with several risk factors and thus is a good candidate for being such an integrative variable. As a comparison, left ventricular mass (LVM), pulse wave velocity (PWV), and creatinine were also tested for association with risk factors. DESIGN: A total of 302 subjects referred for hypertension, were considered. They had a 24-h BP recording and a determination of BRS by two different methods (sequence and alpha coefficient), in two different positions (lying and standing). They were also tested for the presence of left ventricular hypertrophy (LVH) (by echocardiography and electrocardiogram) and had a PWV measurement. Biological testing included serum lipids, blood glucose, creatinine, proteinuria and urinary excretion of microalbumin. RESULTS: There was a strong correlation between the two methods of BRS measurement in each position (P < 0.001). BRS determined by the sequence method in the lying position was correlated significantly and independently with age, 24-h systolic BP, heart rate, and serum cholesterol with P values < 0.001, < 0.001, < 0.01, and < 0.05, respectively. In an univariate analysis, BRS was also correlated with echocardiographic LVM index (r = -0.21, P < 0.05) and PWV (r = -0.27, P < 0.001), which possibly reflects its dependence on both vascular and cardiac damages. CONCLUSION: The present study supports the hypothesis that BRS could encompass the impact over time of several risk factors on the cardiovascular system. Thus, it may constitute a valuable parameter in assessing more precisely the risk of cardiovascular events.

Adult↗

PubMed2002

In vitro study of tocolytic effect of rofecoxib, a specific cyclo-oxygenase 2 inhibitor. Comparison and combination with other tocolytic agents.

OBJECTIVE: The aim of this work was to study and compare the tocolytic effects of rofecoxib with indomethacin, ritodrine, nicardipine and atosiban. We also studied the combination of rofecoxib with each agent. DESIGN: In vitro animal experimental study. SETTING: Non-selective cyclo-oxygenase (COX) inhibitors have potent tocolytic effect. However, they also have major fetal side effects that seem to be due to COX-1 inhibition. A specific COX-2 inhibitor could be a potent tocolytic agent with less fetal toxicity. SAMPLE: Myometrial strips from pregnant Wistar rats at 18 days of gestation. METHODS: Isometric tension was recorded from 112 pregnant rat myometrial strips in vitro. Strips were exposed to increase molar concentration of one drug or combination. MAIN OUTCOME MEASURES: Contractile activity was assessed by calculating the area under the curve, to obtain a dose-response curve of each drug. EC50 and mean maximal inhibiting concentration were compared using ANOVA. Chemical interaction was defined for each combination. RESULTS: The in vitro tocolytic effect of rofecoxib was demonstrated. Contractile activity stopped at a concentration of 1.6 x 10(-7) M. Effective concentrations were 1000 times less than for indomethacin and significantly lower than ritodrine and atosiban. Rofecoxib combined with ritodrine had a synergic effect. Other combinations only had an additive effect. CONCLUSIONS: Rofecoxib has a potent tocolytic effect in vitro. The high specificity and low effective concentrations of COX-2 may result in low fetal toxicity. Animal fetal side effects need to be explored.

Analysis of Variance↗

PubMed2002

Hyperhydration induced by glycerol ingestion: hormonal and renal responses.

The simultaneous time courses of hydromineral hormones (renin-aldosterone system, arginine vasopressin, and atrial natriuretic peptide) and renal responses were examined during and after the completion of hyperhydration induced by glycerol and fluid ingestion. Eight healthy young male Caucasian subjects participated in two separate trials, each including three consecutive phases in a thermoneutral environment. Phases 1 and 3 involved a 90-min period at rest, while phase 2 involved a 120-min period at rest designed to provide either (i) euhydration (control trial) or (ii) hyperhydration induced by ingestion of glycerol (1.1 g/kg body mass) and fluid (21.4 mL/kg body mass). During the 2-h time period of glycerol and fluid ingestion, urine flow, urine osmolality, and plasma levels of hydromineral hormones remained at basal values. In contrast, after hyperhydration completion during phase 3, the diuresis increased markedly together with a dilution of the urine (p < 0.05) while hormonal responses did not change. These results indicate significant differences in renal responses during and after hyperhydration completion and suggest that these changes are independent of fluid-regulating hormonal responses.

Adult↗