Beneficial effect of dl-α-lipoic acid on cyclosporine A induced hyperlipidemic nephropathy in rats

Cyclosporine A (CsA)-induced dyslipidemia is one of the most important risk factors for morbidity and mortality after solid organ transplantation. Reducing this side effect of CsA by dietary agents may be safe, cost-effective, and attractive to both patients and health professionals. Hence the present study was designed to evaluate the role of dl-α-Lipoic acid (LA) in deteriorating the lipid abnormalities induced by CsA in rat kidney. Male albino Wistar rats were divided into four groups. CsA administered at a dose of 25 mg/kg body weight, orally for 21 days showed abnormal changes in the levels of lipoprotein fractions (LDL, HDL and VLDL) and lipid profile in both plasma and renal tissue. Significant alterations were also observed in the activities of lipid metabolizing enzymes. Co-treatment with LA (20 mg/kg body weight, oral gavage, for 21 days) reverted the levels of lipid profile (P < 0.001, P < 0.01) and lipoprotein fractions (P < 0.001, P < 0.01) to near control. The activities of lipid metabolizing enzymes also showed considerable restoration on LA supplementation. The outcome of this study provides evidence that LA (a natural metabolic antioxidant) treatment acts as a potent antilipemic agent against CsA-induced lipid abnormalities.     

Effect of recombinant growth hormone on expression of growth hormone receptor,insulin-like growth factor mRNA and serum level of leptin in growing pigs

Sixteen Large White × Landrace castrated male pigs were allotted into treatment and control group. The treatment group was injected intramuscularly with recombinant porcine growth hormone (rpGH, 4 mg d⁻¹) and the control group with vehicle for 28 days. Animals were slaughtered 4 h after final injection for liver, longissimus dorsi (LD) muscle and blood sampling. Serum concentration of insulin-like growth factor 1 (IGF-I) and leptin were determined by RIA. The total RNA was extracted from tissues to measure the abundance of growth hormone receptor (GHR), IGF-I mRNA by RT-PCR with 18S rRNA internal standard. Results showed that rpGH enhanced the average daily weight gain by 26.1% (P < 0.05), the serum IGF-I concentration by 70.94% (P < 0.01), decreased serum leptin by 34.8% (P < 0.01). The relative abundance of GHR and IGF-I mRNA in liver were increased by 24.45% (P < 0.05) and 45.30% (P < 0.01), respectively, but no difference of GHR (P > 0.05) and IGF-I mRNA (P > 0.05) in LD between GH treated and control group was found. These results suggest that rpGH can up-regulate hepatic GHR and IGF-I gene expression and improve animal growth. However the effect of rpGH on GHR and IGF-I gene expression are tissue-specific.     

Haematological and serum biochemical reference values of snow trout,Schizothorax labiatus habiting in river Sindh of Indian Himalayan region

Haematological and serum biochemical parameters are a valuable tool in determining the wellbeing status of different fish species and response in close association to various biological and environmental factors, therefore the aim of the present study was to establish sex-wise reference values of haemato-biochemical parameters of S. labiatus. The haematological parameters such as haemoglobin (Hb) concentration, total erythrocyte count (RBC), total leucocyte count (WBC), packed cell volume (PCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), mean corpuscular volume (MCV) and serum biochemical parameters such as glucose, cholesterol, urea, total protein, albumin and globulin were analysed. The results revealed that the haematological parameters, i.e., Hb, RBC, WBC and PCV showed significant (P < 0.05) differences with respect to sex. Significantly (P < 0.05) higher values of Hb content (11.18 g dl⁻¹), RBC count (1.88 × 10⁶ mm⁻³) and PCV (36.15%) were noted in male fish than females throughout the study period, while significantly (P < 0.05) higher WBC count was noted in females (20.38 × 10³ mm⁻³) compared to males. However, no significant (P > 0.05) difference was observed in erythrocyte indices like MCH, MCHC and MCV between sexes. The serum biochemical parameters, i.e., glucose, cholesterol and urea, also showed significant (P < 0.05) difference between the sexes, but no significant (P > 0.05) difference was noticed in total protein, albumin and globulin. Significantly (P < 0.05) highest values of glucose (116.76 mg dl⁻¹) and urea (9.01 mg dl⁻¹) were recorded in male S. labiatus, while highest value of cholesterol (223.53 mg dl⁻¹) was noted in females. The information generated in the present study gives the basic reference values of haematological and serum biochemical parameters of S. labiatus which will be useful in monitoring the wellbeing status of fish populations. Moreover, the data will also be helpful to ascertain the occurrence of different clinical and subclinical diseases, which may in turn help to boost the overall production of this species.     

Physiological changes induced by pre-adaptation to high altitude

To study the physiological effects of pre-adaptation to high altitude, seven subjects were submitted to acclimatization at 4350 m followed by intermittent acclimation in a low barometric pressure chamber (5000 m to 8500 m). The subjects then spent 25 days in the Himalayas. Ventilatory and cardiac responses were studied during a hypobaric poikilocapnic hypoxic test performed both at rest and during exercise (100 W) in normoxia and in hypoxia (barometric pressure: 589 hPa, altitude: 4500 m). Haemoglobin, erythrocytes, reticulocytes, packed cell volume, 2,3-diphosphoglycerate (2,3-DPG) and erythropoietin (EPO) were measured. All variables were studied before pre-adaptation to high altitude (A), after the acclimatization period (B), after the acclimation period (C) and after the expedition (D). The ventilatory and cardiac responses were characterized by an increased tidal volume in hypoxia (+ 33% during exercise in B,P < 0.05; + 100% at rest and + 33% during exercise in C,P < 0.05) without any change in respiratory frequency, whereas an increased systolic blood pressure was only observed in C during exercise in hypoxia [+23 mmHg (3.07 kPa),P<0.01]. Arterial O2 saturation was higher in hypoxia in C and D, both at rest (+8.2% and +4.7%,P<0.01, respectively), and during exercise (+6.3% and +6.3%,P<0.01, respectively). Erythrocytes, haemoglobin and packed cell volume did not vary significantly. The number of reticulocytes was higher in B (+172%,P<0.05) and in C (+249%,P<0.05). EPO and 2,3-DPG increased only in C (+ 770%,P<0.01 and +23%,P<0.05, respectively). These results showed that a combination of continuous pre-acclimatization on Mont Blanc and intermittent acclimation in the hypobaric chamber triggered efficient pre-adaptation mechanisms allowing climbers to save 1 to 2 weeks of acclimatization on the mountain without clinical inconvenience.     

Plasma volume in acute hypoxia: comparison of a carbon monoxide rebreathing method and dye dilution with Evans'' blue

Exposure to acute hypoxia is associated with changes in body fluid homeostasis and plasma volume (PV). This study compared a dye dilution technique using Evans' blue (PV_Evans') with a carbon monoxide (CO) rebreathing method (PV_CO) for measurements of PV in ten normal subjects at sea level and again 24 h after rapid passive ascent to high altitude (4,350 m). Hypobaric hypoxia decreased arterial oxygen saturation to 79 (74–83)% (mean with 95% confidence intervals). The PV_Evans' remained unchanged from 3.49 (3.30–3.68) l at sea level to 3.46 (3.24–3.68) l at high altitude. In contrast PV_CO decreased from 3.39 (3.17–3.61) l at sea level to 3.04 (2.75–3.33) l at high altitude (P < 0.05). Compared with sea level, this resulted in an increase of the mean bias between the two methods [from 0.11 (−0.05–0.27) l at sea level to 0.43 (0.26–0.60) l at high altitude] so that the ratio between PV_Evans' and PV_CO increased from 1.04 (0.99–1.09) at sea level to 1.15 (1.06–1.24) at high altitude (P < 0.05). In conclusion, the two methods were not interchangeable as measures of hypoxia-induced changes in PV. The mechanism responsible for the bias remains unknown, but it is suggested that the results may reflect a redistribution of albumin caused by the combined effects in hypoxia of both an increased capillary permeability to albumin and a decrease in PV. As a result, the small perivascular compartment of albumin beyond the endothelium may increase without changes in the overall albumin distribution volume. Accepted: 31 October 1997     

Hematology and blood microelements of sheep in south Bohemia

The efficiency of sheep is dependent on their health and well-being. The blood markers can be critical for improving of the physiological, nutritional and pathological status of sheep organism. The aim of this study was to test the hypotheses that the red and white blood cells and copper (Cu) and zinc (Zn) plasma contents are impacted by altitude and season. The ewes were kept at three farms. Blood samples were divided according to factors of altitude (550 m, 800 m, 950 m above sea level), season (spring, fall) and year. The lowest haemoglobin concentration and value of haematocrit were detected at the altitude of 550 m (66.95 g L⁻¹, 0.36 L L⁻¹) and the highest at the altitude of 950 m (117.96 g L⁻¹, 0.39 L L⁻¹) (P < 0.001). Spring values of haemoglobin and haematocrit were lower than fall values. The highest count of leucocytes was recorded at the altitude 950 m (9.57 G L⁻¹), higher counts were contained in spring (P < 0.001). The lowest percentage of eosinophiles was found at the altitude of 800 m (5.81%) and the highest at the altitude of 550 m (9.26%) (P < 0.01). Phagocytose activities were the highest at the altitude of 950 m (95.07%) and the lowest at the altitude of 550 m (85.04%) (P < 0.001). Phagocytose activities were higher in fall than in spring. The highest Cu concentration was found at the altitude of 550 m and the lowest at the altitude of 800 m (17.04 μmol L⁻¹ vs. 14.37 μmol L⁻¹). Zn levels were higher at altitudes of 950 m and 800 m than at the altitude of 550 m (17.81 μmol L⁻¹, 17.00 μmol L⁻¹ vs. 14.77 μmol L⁻¹). We concluded that hematological markers and trace mineral content in grazed sheep may be impacted by altitude and season.     

Effects of training on lipid metabolism in swimming muscles of sea trout (Salmo trutta)

We examined the effect of exercise intensity and endurance training on plasma free fatty acid (FFA) kinetics and lipid metabolism in swimming muscles of reared sea trout. In both training groups [water current velocities 1 and 2 body lengths per second (bl s⁻¹)] the plasma level of FFAs decreased significantly (P < 0.001) compared to the control group. Similar significant (P < 0.01) post-exercise decrease was observed also in the lipase-esterase activity in the red muscle, but not in white. Moreover, in the group swimming with higher intensity a significantly higher (P < 0.05) lipase-esterase activity in the red muscle was found compared with the group on moderate exercise. As with cytochrome c oxidase activity, a significant elevation in the enzyme activity was also observed after training in the 1 bl s⁻¹ group in red and white muscle (P < 0.05 and P < 0.01, respectively). No changes were observed in β hydroxyacyl CoA dehydrogenase activity. The lipid content was on average nine times higher in red compared to white muscle being 16.7, 21.1, and 24.9% in the red muscle of the control, 1 and 2 bl s⁻¹ groups, respectively, with a significant (P < 0.05) increase after training. We conclude that (1) unlike in mammals, plasma FFA kinetics and oxidation are not linearly related to exercise intensity in reared sea trout, (2) training enhances the capacity to uptake FFA from plasma, and (3) high intensity training shifts the proportion of energy derived from fat oxidation to carbohydrate-derived energy.     

Renierol from marine sponge Haliclona.SP.: A natural inhibitor of xanthine oxidase with hypouricemic effects

The purpose of this study was to evaluate the inhibitory effect of renierol, extracted from marine sponge Halicdona.SP., on xanthine oxidase (XO) and its hypouricemic effect in vivo. Renierol and a positive control, allopurinol, were tested for their effects on XO activity by measuring the formation of uric acid and superoxide radical from xanthine. Renierol inhibited XO in a concentration-dependent and competitive manner. IC₅₀ value was 1.85 μg·ml^{? 1} through the measuring of uric acid and was 1.36 μg.ml^{? 1} through the measuring of superoxide radical. Renierol was found to have an in vivo hypouricemic activity against potassium oxonate-induced hyperuricaemia in mice. After oral administration of renierol at doses of 10, 20 and 30 mg.kg^{? 1}, there was a significant decrease in the serum urate level (4.08 ± 0.09 mg.dl^{? 1}, P < 0.01), (3.47 ± 0.11 mg.dl^{? 1}, P < 0.01) and (3.12 ± 0.08 mg.dl^{? 1}, P < 0.01), when compared to the hyperuricaemic control (6.74 ± 0.23 mg.dl^{? 1}). Renierol was a potent XO inhibitor with hypouricemic activity in mice.     

Naloxone-provoked vaso-vagal response to head-up tilt in men

A double-blind paired protocol was used to evaluate, in eight male volunteers, the effects of the endogenous opiate antagonist naloxone (NAL; 0.05 mg· kg^–1) on cardiovascular responses to 50° head-up tilt-induced central hypovolaemia. Progressive central hypovolaemia was characterized by a phase of normotensive-tachycardia followed by an episode of hypotensive-bradycardia. The NAL shortened the former from 20 (8–40) to 5 (3–10) min (median and range; (P < 0.02). Control head-up tilt increased the means of thoracic electrical impedance [from 35.8 (SEM 2.1) to 40.0 (SEM 1.8) ; P < 0.01 of heart rate [HR; from 67 (SEM 5) to 96 (SEM 8) beats · min^–1, P < 0.02], of total peripheral resistance [TPR; from 25.5 (SEM 3.2) to 50.4 (SEM 10.5)mmHg min 1^–1,P < 0.05] and of mean arterial pressure [MAP; from 96 (SEM 2) to 101 (SEM 2)mmHg, P < 0.02]. Decreases were observed in stroke volume [from 65 (SEM 12) to 38 (SEM 9) ml, P < 0.01], in cardiac output [from 3.7 (SEM 0.7) to 2.5 (SEM 0.5) 1 · mint, P < 0.01], in pulse pressure [from 55 (SEM 4) to 37 (SEM 3)mmHg, P < 0.01] and in central venous oxygen saturation [from 73 (SEM 2) to 59 (SEM 4)%, P < 0.01]. During NAL, mean HR increased from 70 (SEM 3); n.s. compared to control) to only 86 (SEM 9) beats · min^–1 (P < 0.02 compared to control) and MAP remained stable. The episode of hypotensive-bradycardia appeared as mean control HR decreased to 77 (SEM 7)beats · min^–1, TPR to 31.4(SEM 7.7)mmHg · min · 1^–1 and MAP to 60 (SEM 5)mmHg (P < 0.01), and the volunteers were tilted supine. Cardiovascular effects of naloxone on central hypovolaemia included a reduced elevation of HR and blood pressures and provocation of the episode of hypotensive-bradycardia.     

Amelioration of altered antioxidant status and membrane linked functions by vanadium andTrigonella in alloxan diabetic rat brains

Trigonella foenum graecum seed powder (TSP) and sodium orthovanadate (SOV) have been reported to have antidiabetic effects. However, SOV exerts hypoglycemic effects at relatively high doses with several toxic effects. We used low doses of vanadate in combination with TSP and evaluated their antidiabetic effects on antioxidant enzymes and membrane-linked functions in diabetic rat brains. In rats, diabetes was induced by alloxan monohydrate (15 mg/100 g body wt.) and they were treated with 2 IU insulin, 0.6 mg/ml SOV, 5% TSP and a combination of 0.2 mg/ml SOV with 5% TSP for 21 days. Blood glucose levels, activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), Na⁺/K⁺ ATPase, membrane lipid peroxidation and fluidity were determined in different fractions of whole brain after 21 days of treatment. Diabetic rats showed high blood glucose (P < 0.001), decreased activities of SOD, catalase and Na⁺/K⁺ ATPase (P < 0.01,P < 0.001 andP < 0.01), increased levels of GPx and MDA (P < 0.01 andP < 0.001) and decreased membrane fluidity (P < 0.01). Treatment with different antidiabetic compounds restored the above-altered parameters. Combined dose ofTrigonella and vanadate was found to be the most effective treatment in normalizing these alterations. Lower doses of vanadate could be used in combination with TSP to effectively counter diabetic alterations without any toxic effects.     

Effect of insulin on exocrine pancreatic secretion in healthy and diabetic anaesthetised rats

This investigation characterised the effects of exogenous insulin on exocrine pancreatic secretion in anaesthetised healthy and diabetic rats. Animals were rendered diabetic by a single injection of streptozotocin (STZ, 60 mg kg^–1 I.P.). Age-matched controls were injected citrate buffer. Rats were tested for hyperglycaemia 4 days after STZ injection and 7–8 weeks later when they were used for the experiments. Following anaesthesia (1 g kg^–1 urethane I.P.), laparotomy was performed and the pancreatic duct cannulated for collection of pure pancreatic juice. Basal pancreatic juice flow rate in diabetic rats was significantly (p < 0.001) increased whereas protein and amylase outputs were significantly (p < 0.001) decreased compared to control rats. Insulin (1 IU, I.P.) produced in healthy rats significant increases in pancreatic flow rate, amylase secretion and protein output compared to basal (p < 0.05). Insulin action also included a reduction in blood glucose (152.7 ± 16.9 mg dl^–1, n= 6, prior to insulin and 42.0 ± 8.4 mg dl^–1, n= 4, 100 min later). In fact, flow rate and glycaemia showed a strong negative correlation (p < 0.01, Pearson). Pretreatment with atropine (0.2 mg kg^–1, I.V.) abolished the effects of insulin on secretory parameters despite a similar reduction in glycaemia; in this series of experiments the correlation between flow rate and blood glucose was lost. In diabetic rats, insulin (4 IU, I.P.) did not modify exocrine pancreatic secretion. There was a fall in blood glucose (467.6 ± 14.0 mg dl^–1, n= 10, prior to insulin and 386.6 ± 43.6 mg dl^–1, n= 7, 120 min later). Rats, however, did not become hypoglycaemic. Similar results were observed in diabetic atropinized rats. The results of this study indicate that the effects of insulin on exocrine pancreatic secretion in anaesthetised healthy rats are mediated by hypoglycaemia-evoked vagal cholinergic activation. (Mol Cell Biochem 261: 105–110, 2004)     

Elevated CO<Subscript>2</Subscript> Effects on Peatland Plant Community Carbon Dynamics and DOC Production

Northern peatlands are important stores of carbon and reservoirs of biodiversity that are vulnerable to global change. However, the carbon dynamics of individual peatland plant species is poorly understood, despite the potential for rising atmospheric CO₂ to affect the vegetation’s contribution to overall ecosystem carbon function. Here, we examined the effects of 3 years exposure to elevated CO₂ (eCO₂) on (a) peatland plant community composition and biomass, and (b) plant carbon dynamics and the production of dissolved organic carbon (DOC) using a ¹³CO₂ pulse–chase approach. Results showed that under eCO₂, Sphagnum spp. cover declined by 39% (P < 0.05) and Juncus effusus L. cover increased by 40% (P < 0.001). There was a concurrent increase in above- and belowground plant biomass of 115% (P < 0.01) and 96% (P < 0.01), respectively. Vascular species assimilated and turned over more ¹³CO₂-derived carbon than Sphagnum spp. (49% greater turnover of assimilated ¹³C in J. effusus and F. ovina L. leaf tissues compared with Sphagnum, P < 0.01). Elevated CO₂ also produced a 66% rise in DOC concentrations (P < 0.001) and an order of magnitude more ‘new’ exudate ¹³DOC than control samples (24 h after ¹³CO₂ pulse-labelling 2.5 ± 0.5 and 0.2 ± 0.1% in eCO₂ and control leachate, respectively, P < 0.05). We attribute the observed increase in DOC concentrations under eCO₂ to the switch from predominantly Sphagnum spp. to vascular species (namely J. effusus), leading to enhanced exudation and decomposition (litter and peat). The potential for reduced peatland carbon accretion, increased DOC exports and positive feedback to climate change are discussed.     

The study of renin–angiotensin–aldosterone in experimental diabetes mellitus

It is generally accepted that hypertension and other vascular pathologies increase in diabetes mellitus (DM) patients as a result of the renin–angiotensin–aldosterone (RAA) system. In this study, changes in the renin‐angiotensin‐aldosterone (RAA) system level was determined in Streptozotocin (STZ)‐injected rats. A total of 46 female Wistar albino rats (180–220 g body weight) was utilized in these experiments. STZ was given intraperitoneally to induce diabetes in rats. Streptozotocin (60 mg kg⁻¹ body weight) was dissolved in 0·1 m citrate–‐phosphate buffer (pH 4–5). The non‐diabetic rats were injected with sterilized buffer alone to act as a control group. Blood glucose levels were 398±8·2 mg dl⁻¹, 488±11·75 mg dl⁻¹ and 658±29·6 mg dl⁻¹ at days 3, 12 and 30 respectively. The level of plasma renin activity (PRA) was measured as 7·69±1·07 ng ml⁻¹ h⁻¹; 1·82±0·22 ng ml⁻¹ h⁻¹ and 0·67±0·12 ng ml⁻¹ h⁻¹ at days 3, 12 and 30, respectively. These values showed that the PRA levels are decreased with increased time period. Serum angiotensin converting enzyme (ACE, E.C. 3.4.15.1) levels were increased at days 12 and 30 (p<0·05 and p<0·005), whereas serum aldosterone levels were increased at days 3 and 12 (p<0·05). The level of urea and creatinine increased at days 12 and 30 (p<0·05 and p<0·005, respectively) when compared to the control group. The data from these experiments indicate that the PRA level decreased whereas ACE activity level increased in diabetic rats compared with the control. Aldosterone levels increased at the first stage of the experiment, but then decreased by the end of the experiment as a result of changes in renin and ACE levels. Copyright © 1999 John Wiley & Sons, Ltd.     

Body fat responses to a 1‐year combined exercise training program in male coronary artery disease patients

Objective:

To analyze the body fat (BF) content and distribution modifications in coronary artery disease (CAD) patients in response to a 1‐year combined aerobic and resistance exercise training (CET) program.

Design and Methods:

We followed two groups of CAD male patients for 12 months. One group consisted of 17 subjects (57 ± 12 years) who engaged in a CET program (CET group) and the other was a age‐matched control group of 10 subjects (58 ± 11 years). BF content and distribution were measured through dual energy X‐ray absorptiometry (DXA) at baseline and follow‐up.

Results:

We found no differences on body mass and BMI between baseline and end of follow‐up in both groups but, in CET group, we found significant reductions in all analyzed BF depots, including total BF (21.60 ± 6.00 vs. 20.32 ± 5.89 kg, P < 0.01), % total BF (27.8 ± 5.5 vs. 26.4 ± 5.4%, P < 0.05), trunk fat (12.54 ± 3.99 vs. 11.77 ± 4.01 kg, P < 0.05), % trunk fat (31.1 ± 6.9 and 29.2 ± 7.1%, P < 0.05), appendicular fat (8.22 ± 2.08 vs. 7.72 ± 2.037 kg, P < 0.01), % appendicular fat (25.7 ± 4.9 and 24.5 ± 4.9%, P < 0.05), and abdominal fat (2.95 ± 1.06 vs. 2.75 ± 1.10 kg, P < 0.05). Control group showed significant increase in appendicular fat (7.63 ± 1.92 vs. 8.10 ± 2.12 kg, P < 0.05).

Conclusions:

These results confirm the positive effect of CET on body composition of CAD patients, despite no changes in body mass or BMI. In this study, we observed no alterations on BF distribution meaning similar rate of fat loss in all analyzed BF depots. These results also alert for the limitations of BMI for tracking body composition changes.     

Decreased α1-Adrenergic Receptor Binding in the Cerebral Cortex and Brain Stem during Pancreatic Regeneration in Rats

The purpose of this study was to investigate the role of brain α₁-adrenergic receptor binding in the rat model of pancreatic regeneration using 60–70% pancreatectomy. The α₁-adrenergic receptors kinetics was studied in the cerebral cortex and brain stem of sham operated, 72 h pancreatectomised and 7 days pancreatectomised rats. Scatchard analysis with [³H]prazosin in cerebral cortex and brain stem showed a significant decrease (P < 0.01), (P < 0.05) in maximal binding (B _max) with a significant decrease (P < 0.001), (P < 0.01) in the K _d in 72 h pancreatectomised rats compared with sham respectively. Competition analysis in cerebral cortex and brain stem showed a shift in affinity during pancreatic regeneration. The sympathetic activity was decreased as indicated by the significantly decreased norepinephrine level in the plasma (P < 0.001), cerebral cortex (P < 0.01) and brain stem (P < 0.001) of 72 h pancreatectomised rats compared to sham. Thus, from our results it is suggested that the central α₁-adrenergic receptors have a functional role in the pancreatic regeneration mediated through the sympathetic pathway.     

Increased Lipid Peroxidation and Ascorbic Acid Utilization in Testis and Epididymis of Rats Chronically Exposed to Lead

The hypothesis has been recently presented that lead may exert its negative effect at least partially through the increase of reactive oxygen species (ROS) level in tissues. However, little is known about the influence of lead intoxication on equilibrium between generation and elimination of ROS in the male reproductive system. Sexually mature male Wistar rats were given ad libitum 1% of aqueous solution of lead acetate (PbAc) for 9 months. Significantly higher lead concentrations were found in blood [median 7.03 (Q25–Q75: 2.99–7.65) versus 0.18 (0.12–0.99) μg dl⁻¹, P < 0.01], caput epididymis [median 5.51 (Q25–Q75: 4.31–7.83) versus 0.51 (0.11–0.80) μg g⁻¹ d.m., P < 0.001], cauda epididymis [median 5.88 (Q25–Q75: 4.06–8.37) versus 0.61 (0.2 – 1.08) μg g⁻¹ d.m., P < 0.001] and testis [median 1.81 (Q25–Q75: 0.94–2.31) versus 0.17 (0.03–0.3) μg g⁻¹ d.m., P < 0.01] of lead-intoxicated rats when compared to the control. The concentration of ascorbyl radical, generated in vitro from l-ascorbic acid (present in tissues in vivo) was measured by means of Electron Paramagnetic Resonance (EPR) spectroscopy. The EPR signal of ascorbyl radical in caput epididymis, cauda epididymis, testis and liver of lead acetate-treated animals revealed a significant decrease by 53%, 45%, 40% and 69% versus control tissues, respectively. Plasma l-ascorbic acid content measured by high performance liquid chromatography (HPLC) method and total antioxidant status (TAS) measured by means of spectrophotometry were also significantly lower in the intoxicated versus control animals (28% and 21%, respectively). In the group exposed to lead the concentration of lipid peroxide in homogenates of the reproductive system organs was significantly elevated versus control group. It can be assumed that the lower EPR signal was caused by decreased tissue concentrations of l-ascorbic acid. The latter may have resulted from consumption of ascorbic acid for scavenging of ROS excess in tissues of animals chronically exposed to lead.     

REGULATION OF THE 24H BODY TEMPERATURE RHYTHM OF WOMEN IN LUTEAL PHASE: ROLE OF GONADAL STEROIDS AND PROSTAGLANDINS

An investigation into whether the rise in the 24h body temperature rhythm observed in the luteal menstrual phase is antagonized by the administration of prostaglandin synthesis inhibitors has been made. Intravaginal body temperature was monitored continuously for 24 h, once in the follicular and twice in the luteal phase. In the luteal phase, women were studied both without and with the simultaneous administration of a prostaglandin synthesis inhibitor (lysine acetylsalicylate; 1.8 g every 6 h orally). The progesterone/estradiol ratio (measured at 17:00h each day) was related to mesor (r=0.825; P<0.001), acrophase (r=0.682; P<0.02), and amplitude (r=?0.731; P<0.001) of the 24h body temperature rhythm. Luteal phase elevation of the progesterone/estradiol ratio was associated with a 0.32±0.07°C increase in mesor (P<0.01), a 0.11±0.02°C decrease in amplitude (P<0.001), and a 34.8±11.6 min delay in acrophase (P<0.03) of the 24h body temperature rhythm. Prostaglandin synthesis inhibitors did not counteract these modifications. The present data shows that the modifications of the circadian parameters of the 24h body temperature rhythm observed during the luteal phase of the menstrual cycle are strictly related to modifications of the progesterone/estradiol ratio, and presumably independent of prostaglandin synthesis.     

Post-exercise gastric emptying of carbohydrate solutions determined using the 13C acetate breath test

In an attempt to measure gastric emptying of carbohydrate solutions after exercise, we used the ¹³C acetate breath test to differentiate the gastric emptying of three approximately isoenergetic carbohydrate solutions (i.e. glucose, glucose polymer and sucrose) from each other and from water. On four separate occasions, six post-absorptive subjects walked on an inclined treadmill at 70% maximum oxygen uptake for 1 h and were then given 330 ml of one of the solutions in which 150 mg of sodium 1-[¹³C] acetate had been dissolved. Breath samples were collected at regular (2–30 min) intervals over the next 3.5 h for analysis of expired ¹³CO₂ by isotope ratio mass spectrometry. When water was given, all subjects reached peak breath enrichment after 30 min, and had a mean (SE) gastric emptying time of 33.2 (1.6) min. Peak breath enrichment occurred later for sucrose and glucose polymer at 54.3 (3.1) min and 59.0 (2.1) min respectively (P < 0.01), and for glucose this was even later, at 62.3 (1.0) min (P < 0.05). Calculated gastric emptying times for sucrose and glucose polymer were almost identical [66.5 (2.5) and 69.8 (2.9) min respectively], whereas that for glucose was significantly slower [76.8 (3.2) min; P < 0.02], probably reflecting the effects of increased osmolality. The gastric emptying of all carbohydrates were significantly longer than for water (P < 0.01). These results show that in the post-exercise state the ¹³C acetate breath test can be used to differentiate the gastric emptying rates of water and carbohydrate solutions of different properties.     

Influence of daylight and incubation interval on water column respiration in tropical fish ponds

Water column respiration (WCR) was measured in dark BOD bottles for 2, 4 and 8 h intervals during 22 h periods in two 1000 m² ponds stocked withOreochromis niloticus at 1 m^–2, and fertilized weekly with chicken litter at 750 kg total solids ha^–1. Mean WCR ranged from a low of 0.39 mg l^–1 for 8 h nocturnal intervals to a high of 0.62 mg l^–1 for 2-h diurnal intervals. WCR was significantly influenced by daylight and time into the diurnal or nocturnal period when it was determined. Mean WCR was significantly greater during the day than during the night (P<0.01). During the day, 2 h incubation intervals resulted in significantly higher WCR than 4 h or 8 h intervals (P<0.01); length of incubation interval did not significantly influence nocturnal WCR (P>0.05). Higher WCR during the day and during short diurnal incubation intervals was attributed to greater availability of photosynthetic respiration substrate. Diurnal, diel, or nocturnal WCR could be best estimated by a single 2, 4 or 8 h incubation interval, respectively, beginning at 0800 h.     

Body mass, body composition and sleeping metabolic rate before, during and after endurance training

Metabolic rate, more specifically resting metabolic rate (RMR) or sleeping metabolic rate (SMR), of an adult subject is usually expressed as a function of the fat-free mass (FFM). Chronic exercise is thought to increase FFM and thus to increase RMR and SMR. We determined body mass (BM), body composition, and SMR before, during, and after an endurance training programme without interfering with energy intake. The subjects were 11 women and 12 men, aged 37 (SD 3) years and body mass index 22.3 (SD 1.5) kg · m^–2. The endurance training prepared subjects to run a half marathon competition after 44 weeks. The SMR was measured overnight in a respiration chamber. Body composition was measured by hydrostatic weighing. Measurements were performed at 0, 8, 20, 40, and 90 weeks after the start of the training. The BM had decreased from a mean value of 66.6 (SD 6.9) to 65.6 (SD 6.7) kg (P<0.01), fat mass (FM) had decreased from 17.1 (SD 3.9) to 13.5 (SD 3.6) kg (P<0.001), and FFM had increased from 49.5 (SD 7.3) to 52.2 (SD 7.6) kg (P<0.001) at 40 weeks. Mean SMR before and after 40 weeks training was 6.5 (SD 0.7) and 6.2 (SD 0.6) MJ · day^–1 (P<0.05). The decrease in SMR was related to the decrease in BM (r=0.62,P=0.001). At 90 weeks, when most subjects had not trained for nearly a year, BM and SMR were not significantly different from the initial value while FM and FFM had not changed since week 40 of training. In conclusion, it was found that an exercise induced increase in FFM did not result in an increase in SMR. There was an indication of the opposite effect, a decrease in SMR in the long term during training, possibly as a defence mechanism of the body in the maintenance of BM.