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1.
An experiment was carried out on Sprague-Dawley rats (adult males) that for 50 days were administered, in the drinking water, NaF and NaF with caffeine (doses, respectively: 4.9 mg of NaF/kg body mass/24 h and 3 mg of caffeine/kg body mass/24 h). Disturbances were noted in the functioning of kidneys, which were, particularly noticeable after the administration of NaF with caffeine. Changes in the functioning of kidneys were also confirmed by such parameters as the level of creatinine, urea, protein, and calcium. Modifications of the enzymatic antioxidative system (superoxide dismutase, catalase, and glutathione peroxidase) and lipid peroxidation (malondialdehyde) were also observed. Changes in the contents of the above parameters as well as pathomorphological examinations suggest increased diuresis, resulting in dehydration of the rats examined.  相似文献   

2.
Summary Na+,K+-ATPase, HCO 3 -ATPase, Ca2+,Mg2+,-ATPase, Ca2+-ATPase, and alkaline phosphatase activities were measured in cultures of osteoblastlike cells treated with fluoride and cortisol separately and in combinations. Low concentrations of cortisol increased HCO 3 -ATPase (10−11 to 10−18 M cortisol) and alkaline phosphatase (10−11 to 10−9 M cortisol) activities, but higher cortisol concentrations reduced these activities. Na+,K+-ATPase, Ca2+,Mg2+-ATPase, and Ca2+-ATPase activities tended only to be reduced by cortisol. Fluoride (10−6 and 5×10−6 M) increased HCO 3 -ATPase and alkaline phosphatase activities, but these activities were similar to controls in the presence of 10−5 M fluoride. Ca2+,Mg2+-ATPase activity was decreased and Na+,K+-ATPase activity was increased as the concentration of fluoride increased (10−6 to 10−5 M). Preliminary experiments with fluoride indicated that lower concentrations (10−7 M) were without effect. Cortisol concentrations of 10−9 and 10−8 M were chosen for studies with combinations of cortisol and fluoride because the effects of these concentrations on alkaline phosphatase activity were opposite, i.e. 10−9 M increased whereas 10−8 M decreased activity. Fluoride concentrations of 10−6, 5×10−6, and 10−5 M were chosen because a peak of alkaline phosphatase activity occurred at 5×10−6 M fluoride. Higher (10−4 M) and lower (10−7 M) fluoride concentrations were without effect. The effects of combinations of cortisol and fluoride depend on the enzyme activity measured. Fluoride (10−6 M) combined with cortisol (10−9 M) produced a peak of Na+,K+-ATPase activity. The increased activity obtained with all concentrations of fluoride alone was preserved when fluoride was combined with 10−8 M cortisol, although the activity tended to be reduced at 5×10−6 and 10−5 M fluoride. HCO 3 -ATPase activity was increased by fluoride combined with 10−8 M cortisol and decreased by fluoride combined with 10−9 M cortisol compared to the activities obtained with fluoride alone. The decrease in Ca2+,Mg2+-ATPase activity caused by fluoride alone was prevented by 10−9 and enhanced by 10−8 M cortisol, although all treatments produced the same activity at 10−5 M fluoride. Ca2+-ATPase activity tended to be increased by combinations of fluoride and cortisol, but significantly so only at 10−5 M fluoride in combinations with 10−8 and 10−9 M cortisol. Alkaline phosphatase activity was increased by fluoride combined with 10−9 M cortisol and decreased by fluoride combined with 10−8 M cortisol compared to the activities obtained with fluoride alone. These results suggest that the abilities of bone cells to regulate ion transport (as reflected in their ion-transporting ATPase activities) are modulated by glucocorticoids and fluoride. Inasmuch as these cells may regulate the ionic composition and concentrations of the bone extracellular fluid (ECF) in vivo, the modulation of their activities by cortisol and fluoride may result in altered bone ECF composition. This work was supported by Grant NAG-2-108 from the National Aeronautics and Space Administration, D.C., and Grant PO1 NS15767 from the National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, MD.  相似文献   

3.
In our study, the short-term effects of caffeine on L- arginine metabolism in the brains of rats were investigated. Caffeine was given orally at two different doses: 30 mg/kg and 100 mg/kg (a high non-toxic dose). Brain tissue arginase activity in rats from the caffeine-treated groups decreased significantly compared with the control group. Malondialdehyde (MDA) levels in the brain tissue and serum of animals in the caffeine groups also decreased significantly. Brain tissue and serum nitric oxide (NO) levels increased significantly after caffeine administration. Tumor necrosis factor-α (TNF-α) levels were also investigated in rat serum, but there was no statistically significant difference between the TNF-α levels of the caffeine-treated rats groups and the control rats. Our study indicates that brain arginase activity decreases after caffeine administration at doses of 30 mg/kg and 100 mg/kg. As a result, we can say that arginine induces production of NO in the organism.  相似文献   

4.
5.
Twenty-three hypertensive outpatients aged 18–53 yr (average: 39.8±10.4 yr) were classified into two groups according to body mass index (BMI). Six patients exceeded the BMI limit, set at 30 kg/m2. All were treated with 100 mg/d spironolactone and were subject to before and after measurements of their arterial pressure, efflux rate constants of zinc from lymphocytes (total ERCt-Zn and ouabain-dependent ERCos-Zn), serum zinc (Zn-s), lymphocyte zinc (Zn-l), serum aldosterone (Ald-s), plasma renin activity (PRA), serum sodium (Na-s), and potassium (K-s). After 7 d of spironolactone treatment, the ERCt-Zn change in normal-weight patients was +0.78±0.57, and −0.22±0.69 in obese patients. In the same manner, the change of ERCos-Zn was +0.59±0.94 and −0.025±0.32 in normal and obese patients, respectively. Serum Zn was increased in normal-weight patients but remained unchanged in the obese. The initial lymphocyte zinc values were significantly lower in obese patients, but increased up to normal values after spironolactone treatment.  相似文献   

6.
The aim of this study was to evaluate the effect of magnesium (Mg) loading (10.0 mg Mg/kg body wt) and daily Mg supplements (5.0 mg Mg/kg body wt) on Mg deficiency shown by increased and not by decreased serum Mg concentration during hypokinesia (decreased km number/d). The studies were done during 30 d of prehypokinesia and 364 d of hypokinesia (HK) periods. Forty endurance-trained volunteers aged 22–26 yr with a peak VO2 max of 66.3 mL·kg−1 min−1 and with an average 15.0 km/d running distance were chose as subjects. They were equally divided into four groups:
1.  Unsupplemented ambulatory control subjects (UACS).
2.  Unsupplemented hypokinetic subjects (UHKS).
3.  Supplemented hypokinetic subjects (SHKS).
4.  Supplemented ambulatory control subjects (SACS).
The SHKS and SACS groups took daily 5.0 mg elemental Mg/kg body wt and subjected to Mg loading (10.0 mg Mg/kg body wt). Both the SHKS and UHKS groups were maintained under an average running distance of 4.7 km/d, whereas the SACS and UACS groups did not experience any modifications to their normal training routines and diets. During the prehypokinetic and hypokinetic periods, excretion of Mg in feces and urine, concentration of Mg in serum, and Mg balance were measured. urinary and serum sodium (Na), potassium (K), and calcium (Ca) were also determined. In both SHKS and UHKS groups, fecal Mg loss, urinary excretion of electrolytes, and serum concentrations of electrolytes increased significantly (p≤0.05) when compared with the SACS and UACS groups. During Mg loading tests, urinary and fecal Mg excretion was also greater in the SHKS and UHKS groups than in the SACS and UACS groups. Throughout the study, Mg balance was negative in the SHKS and UHKS groups, whereas in the SACS and UACS groups, Mg balance was positive. It was concluded that significant losses of Mg occurred in the presence of negative Mg balance and Mg deficiency in endurance-trained subjects during prolonged exposure to HK, daily mg supplements, and Mg loading tests. This suggests that Mg is not entering or being retaining by the bones and cells of many tissues where most Mg is deposited normally, resulting in Mg deficiency as was shown by the increased serum Mg concentration.  相似文献   

7.
The present study was undertaken to evaluate the fluoride status in the general healthy population of Barcelona. Serum and urine fluoride ionic concentration was determined in a random sample of 250 subjects (age range 15–90 yr) by the Orion fluoride electrode system to determine the normal range of fluoride in this population. The results obtained show that in the general population of Barcelona, fluoride ionic serum concentration ranges between 1 and 47 μg/L (x = 17.5 ± 9.7 μg/L) and fluoride ionic urine concentration ranges between 156 and 1990 μg/24 h (x = 671 ± 373 μg/24 h). The mean serum fluoride concentration of the younger population was shown to be significantly greater (p < 0.05) than that of the older group. No sex-related difference was found.  相似文献   

8.
Arginase activity in erythrocytes is higher in patients with arterial hypertension and atherosclerosis as compared with healthy patients. Therapy with either lisinopril alone or in combination with simvastatin for 3–6 months causes a decrease in the arginase activity to the control level. Both the monotherapy and the combination therapy increased the concentrations of N2, N3, and total N2 + N3 in the plasma of hypertensive patients. The N2 + N3 concentration in erythrocytes decreases in hypertensive patients but is completely restored after therapy with lisinopril alone or in combination with simvastatin. Thus, lisinopril and lisinopril plus simvastatin display a pronounced and equal normalizing effect on arginase activity in human erythrocytes, which is elevated in hypertension, as well as on the endothelial nitric oxide synthase activity, which is decreased in hypertension.  相似文献   

9.
The influence of brackish phytoplankton cell classes upon the response of urea decomposition was investigated in Lake Nakaumi. The urea decomposition rate was 5 to 350 μmol urea m−3 h−1 in the light and 3 to 137 μmol urea m−3 h−1 in the dark. The urea decomposition rates in the light were obviously higher than in the dark. An extremely high rate (350 μmol urea m−3 h−1) was observed in Yonago Bay. The rate in the smaller fraction (<5 μm) exceeded that in the middle (5–25 μm) and larger fractions (>25 μm). The chlorophyll- and photosynthesis-specific rates for urea decomposition in the light were 0.5 to 3.9 μmol urea mg chl.a −1 h−1 and 0.3 to 1.3 μmol urea mg photo.C−1. The specific urea decomposing activities were higher in the smaller fraction than in the other two fractions. The present results suggest that in brackish waters urea decomposition occurred with coupling to the standing crop and photosynthetic activity of phytoplankton. Received: May 22, 1999 / Accepted: August 15, 1999  相似文献   

10.
Increased exposure to fluorine-containing compounds leads to accumulation of fluorides in hard tissues of bones and teeth, which may result in numerous skeletal and dental disorders. This study evaluates the influence of methionine and vitamin E on fluoride concentration in bones and teeth of rats subjected to long-term exposure to sodium fluoride in drinking water. The study was conducted in 30 3-month-old female Wistar FL rats. The animals were divided into five groups, six rats per group. The control group consisted of rats receiving only distilled water as drinking water. All other groups received NaF in the amount of 10 mg/kg of body mass/day in their drinking water. In addition, respective animal groups received: NaF + Met group—10 mg of methionine/kg of body mass/day, NaF + Met + E group—10 mg of methionine/kg of body mass/day and 3 mg of vitamin E (tocopheroli acetas)/rat/day and NaF + E group—3 mg of vitamin E/rat/day. Femoral bones and incisor teeth were collected for the study, and the fluoride concentration was determined using a fluoride ion-selective electrode. Fluoride concentration in both bones and teeth was found to be higher in the NaF and NaF + Met groups compared to the control group. In groups NaF + Met + E and NaF + E, the study material contained much lower fluoride concentration compared to the NaF group, while the effect was more prominent in the NaF + E group. The results of the studies indicate that methionine and vitamin E have opposite effects on accumulation of fluorides in hard tissue in rats. By stimulating fluoride accumulation, methionine reduces the adverse effect of fluorides on soft tissue, while vitamin E, which prevents excessive accumulation of fluorides in bones and teeth, protects these tissues from fluorosis. Therefore, it seems that combined application of both compounds would be optimal for the prevention of the adverse effects of chronic fluoride intoxication.  相似文献   

11.
A field experiment conducted at Central Rice Research Institute, Cuttack, during three successive seasons showed that with the 120-day-duration variety Ratna two dual crops ofAzolla pinnata R. Brown (Bangkok isolate) could be achieved 25 and 50 days after transplanting (DAT) by inoculating 2.0 t ha−1 of fresh Azolla 10 and 30 DAT respectively. One basal crop of Azolla could also be grown using the same inoculum 20 days before transplanting (DBT) in fallow rice fields. The three crops of Azolla grown—once before transplanting and twice after transplanting—gave an average total biomass of 38–63 and 43–64 t ha−1 fresh Azolla containing 64–90 and 76–94 kg N ha−1 respectively in the square and rectangular spacings. Two crops of Azolla grown only as a dual crop, on the other hand, gave 26–39 and 29–41 t ha−1 fresh Azolla which contained 44–61 and 43–59 kg N ha−1 respectively. Growth and yield of rice were significantly higher in Azolla basal plus Azolla dual twice incorporated treatments than in the Azolla dual twice incorporation, Azolla basal plus 30 kg N ha−1 urea and 60 kg N ha−1 urea treatments. Azolla basal plus 30 kg N ha−1 urea and 60 kg N ha−1 urea showed similar yields but Azolla dual twice incorporation was significantly lower than those. The different spacing with same plant populations did not affect growth and yield significantly, whereas Azolla growth during dual cropping was 8.3 and 64% more in the rectangular spacing than in the square spacing in Azolla basal plus Azolla dual twice incorporation and Azolla dual twice incorporation treatments.  相似文献   

12.
Diel variations in urea decomposing activity in the euphotic zone of brackish Lake Nakaumi were measured under fixed light intensity. The decomposition rate of urea was 17 to 44 μ mol urea m−3 h−1 in the light and 10 to 27 μ mol urea m−3 h−1 in the dark. Higher decomposition rates were obtained in the upper euphotic zone. A clear diel periodicity in the urea decomposition rate was observed, with high rates from 1200 to 1600 and low rates from 0000 to 0400. Chlorophyll a specific decomposing activity ranged from 12 to 21 μg urea C mg chl.a −1 h−1 in the light and 7 to 13 μg urea C mg chl.a −1 h−1 in the dark. In the light, high values were obtained from 1600 to 2000 and low values from 0400 to 0800. The diel change in specific decomposing activity exhibited a similar pattern to that of the photosynthetic assimilation number, following the diel change in photosynthetic activity. Received: March 10, 1999 / Accepted: October 22, 1999  相似文献   

13.
Simultaneous measurements of cardio-respiratory variables, oxygen uptake and whole body urea/ammonia/tritiated water effluxes were performed on cannulated gulf toadfish, Opsanus beta, before and after intra-arterial injection of the vasoactive agents, adrenaline, isoproterenol and arginine vasotocin. These experiments were conducted to test the hypothesis that the phenomenon of pulsatile urea excretion might reflect sudden changes in the general diffusive properties of the gill for solute transfer. Injection of isoproterenol (final nominal circulating level = 10−6 mol l−1), was used as a tool to maximise the diffusive and perfusive conditions for branchial solute transfer. This protocol caused a pronounced reduction in arterial blood pressure, an elevation of cardiac frequency and associated increases in whole body urea and tritiated water effluxes; ammonia excretion and oxygen uptake were unaffected. Injection of adrenaline (final nominal circulating level=10−6 mol l−1), caused a significant increase in arterial blood pressure and a tachycardia, yet nitrogen excretion and oxygen uptake were unaffected. Injection of arginine vasotocin, caused a dose-dependent (final nominal circulating levels = 10−11–10−9 mol l−1) increase in arterial blood pressure without affecting cardiac or ventilation frequency. At the two higher concentrations, arginine vasotocin caused large and transient increases in urea excretion without significantly affecting ammonia, water or oxygen fluxes. These results suggest that increased gill diffusive or perfusive conductance, while capable of augmenting urea efflux, cannot fully explain the sudden and massive increases in urea transfer associated with pulsatile urea excretion in toadfish. It is suggested that pulsatile urea excretion in this species may reflect a specific enhancement of urea excretion under the control of the neurohypophyseal hormone, arginine vasotocin. Accepted: 21 April 1998  相似文献   

14.
In the present study, the protective effect of curcumin against sodium fluoride-induced nephrotoxicity was evaluated in rats. Renal injury was induced by daily administration of 600 ppm sodium fluoride in drinking water for 1 week. One week before the administration of fluoride, the animals selected as study group were given curcumin (10 and 20 mg/kg body weight, intraperitoneally). After 1 week, lipid peroxidation level, activities of superoxide dismutase, catalase, and level of glutathione in kidney homogenate were measured. Blood serum samples were examined for creatinine, serum urea, and blood urea nitrogen levels. Another group of rats received vitamin C (10 mg/kg) as standard antioxidant. The results show that curcumin and vitamin C treatment prior to fluoride administration normalized the levels of serum creatinine, serum urea, and blood urea nitrogen. Moreover, curcumin and vitamin C administrations prevented the antioxidant enzyme decreasing and lipid peroxidation levels imbalance. In conclusion, curcumin treatment at the doses of 10 and 20 mg/kg (intraperitoneally) showed significant nephroprotective effects.  相似文献   

15.
First, the effect of different levels of nitrogen source on clavulanic acid (CA) production was evaluated in batch cultivations utilizing complex culture medium containing glycerol and three different levels of soy protein isolate (SPI). Cellular growth, evaluated in terms of the rheological parameter K, was highest with a SPI concentration of 30 g.L−1 (4.42 g.L−1 N total). However, the highest production of CA (380 mg.L−1) was obtained when an intermediate concentration of 20 g.L−1 of SPI (2.95 g.L−1 total N) was used. To address this, the influences of volumetric flow rate (F) and glycerol concentration in the complex feed medium (CsF) in fed-batch cultivations were investigated. The best experimental condition for CA production was F=0.01 L.h−1 and CsF=120 g.L−1, and under these conditions maximum CA production was practically twice that obtained in the batch cultivation. A single empirical equation was proposed to relate maximum CA production with F and CsF in fed-batch experiments.  相似文献   

16.
Explants of four F1 hybrids (OMR 36-41/1, OMR 36-41/2, OMR 36-41/4 and OMR 36-41/5) and two cultivars (Rayong 1 and Rayong 60) of cassava (Manihot esculenta Crantz) were subjected to different combinations of 2,4-dichlorophenoxyacetic acid (2,4-D), 1-naphthaleneacetic acid (NAA), kinetin (KIN) and N6-benzylaminopurine (BAP) to induce somatic embryogenesis, organogenesis and micropropagation. Shoot apices of the F1 hybrids exhibited higher frequency (62 – 74 %) of proliferation of somatic embryos than the cultivars (21 – 43 %) in Murashige and Skoog basal medium supplemented with 8 mg dm−3 2,4-D and 0.5 mg dm−3 NAA. Nodal explants of regenerated plantlets were rapidly micropropagated with 90 % efficiency on a medium containing 0.1 mg dm−3 NAA and 0.05 mg dm−3 BAP irrespective of explant source. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

17.
Microsphere and morphometric techniques were used to investigate any circulatory changes that accompany secretion by the salt glands of hatchling Chelonia mydas. Salt glands were activated by a salt load of 27.0 mmol NaCl kg body mass (BM)−1, resulting in a mean sodium secretion rate of 4.14 ± 0.11 mmol Na kg BM−1 h−1 for a single gland. Microsphere entrapment was approximately 160–180 times greater in the active salt gland than the inactive gland, inferring a similar change in blood flow through salt gland capillaries. The concentration of microspheres trapped in the salt gland was significantly correlated with the rate of tear production (ml kg BM−1 h−1) and the total rate of sodium secretion (mmol Na kg BM−1 h−1) but not with tear sodium concentration (mmol Na l−1). Adrenaline (500 μg kg BM−1) inhibited tear production within 2 min and reduced microsphere entrapment by approximately 95% compared with active glands. The volume of filled blood vessels increased from 0.03 ± 0.01% of secretory lobe volume in inactive salt gland sections to 0.70 ± 0.11% in active gland sections. The results demonstrate that capillary blood flow in the salt gland of C. mydas can regulate the activity of the gland as a whole. Accepted: 12 July 2000  相似文献   

18.
Effects of the burrowing mayfly, Hexagenia, on nitrogen and sulfur fractions of sediment, and overlying water were determined. Laboratory microcosms were used to reproduce the benthic environment. The activities of Hexagenia increased sediment Eh (1.98 ± 0.486 (22) mV · day −1), and decreased pH in sediment (−0.007 ± 0.001 (22) day −1) and overlying water(-0.024 ± 0.004 (10) day−1). In the control, Eh decreased and pH did not change. The presence of Hexagenia also markedly increased ammonia in sediment (5.46 ± 0.14 (22) ppm N · day−1) and overlying water (0.792 ± 0.154 (10) ppm N · day−1), while the control did not change. In addition, the sulfate fraction of sediment (0.177 ± 0.006 (17)% dry mass) and water (50.0 ± 4.9 (5) mg · I−1) in microcosms with Hexagenia was greater than that of the control (0.151 ± 0.005 (16)% dry mass; 14.7 ± 1.71 (3) mg · 1−1) at the termination of the experiment. Hexagenia may also stimulate the mineralization of carbon-bonded sulfur. The general role of Hexagenia in altering sediment chemistry is discussed.  相似文献   

19.
Experimental ecology methods and chlorophyll fluorescence technology were used to study the effects of different concentrations of manganese (10−12– 10−4 mol L−1) on the growth, photosystem II and superoxide dismutase (SOD) activity of Amphidinium sp. MACC/D31. The results showed that manganese had a significant effect on the growth rate, fluorescence parameters (maximal photochemical efficiency of PSII (F v /F m ), photochemical quenching (qP) and non-photochemical quenching (NPQ)) in the exponential stage (days 1–3) and SOD activity of Amphidinium sp. (P < 0.05). F v/F m in the exponential stage in 10−12 mol L−1 manganese concentration was significantly lower whilst qP and NPQ significantly higher than those in the other concentrations. F v /F m (days 6–9) in 10−4 mol L−1 manganese was significantly higher than those in the other concentrations. F v /F m (days 3–6) increased with increased concentration of manganese from 10−12 to 10−4 mol L−1. The values of qP and NPQ decreased with decreased concentrations of manganese, except for those in days 4–6. F v /F m under each concentration increased earlier and decreased later with culture stage whilst NPQ decreased earlier and increased later. The SOD activity increased with increased concentration of manganese from 10−12 to 10−8 mol L−1. The SOD activity in 10−4 mol L−1 manganese was significantly higher than those in the other concentrations and in 10−12 mol L−1 manganese, it was significantly lower than those in the other concentrations.  相似文献   

20.
In 1985, Paterson and Bettger found hypoplastic hematopoiesis in severely zinc-deficient rats. Therefore, we investigated plasma erythropoietin concentration in zinc-deficient rats. Forty 4-wk-old male Sprague-Dawley rats were assigned into 4 dietary treatment groups of 10 for the 4-wk study: zinc-deficient group (4.5 mg zinc and 35 mg iron/kg; −Zn), iron-deficient group (30 mg zinc/kg, no supplemental iron; −Fe), zinc/iron-deficient group (4.5 mg zinc/kg, no supplemental iron; −Zn−Fe), and control group (AIN-93G; Cont). Water intake determined at d 19 was similar among all treatment groups. At d 27–28, bioimpedance was measured. The intracellular water/extracellular water ratio was significantly increased in the −Zn group (p<0.05). Compared to the Cont, group, the plasma erythropoietin concentration was increased by iron deficiency and decreased by zinc deficiency (p<0.01). Hematocrit was significantly decreased in both the −Fe and −Zn−Fe groups and was significantly increased in the −Zn group (p<0.01). Transferrin saturation in the −Fe and −Zn−Fe groups was significantly lower than the Cont group (p<0.01), and that of the −Zn group was highest among all groups. The low plasma erythropoietin concentration might account for depressed hematopoiesis associated with zinc deficiency.  相似文献   

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