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941.
利用尼龙膜作为介质,以0.4mol/L的NaOH为层析液,进行膜上层析,分离经放射性同位素标记的核酸探针和未掺入的放射性游离单核苷酸,再经放射性强度测定即可计算出标记后的核酸探针的放射性比活。方法简单快捷,产生的放射性废物少,完全可以替代经典的三氯乙酸沉淀法及滤膜吸附法。 相似文献
942.
Jemec A Drobne D Tisler T Trebse P Ros M Sepcić K 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2007,144(4):303-309
The most commonly used toxicity test worldwide is the acute Daphnia magna test. The relevance of acetylcholinesterase (AChE) and glutathione S-transferase (GST) activity in D. magna exposed to chromium, cadmium, and diazinon was evaluated in connection with this standard test. We found no link between enzyme activities and immobility. Concentrations of Cr(6+) up to 280 microg/L had no effect on AChE and GST activities, while 20% immobility was observed. At concentrations of 20-25 microg/L of Cd(2+) AChE activity was increased by about 50%. The effect of diazinon on both enzymes was insignificant up to concentrations that caused 27% immobility. Consequently, while the use of AChE and GST activities is recommended when the mode of action of chemicals is studied, the value of these biomarkers in routine acute toxicity tests is limited because the relationship between enzyme activities and immobility of D. magna exposed to different chemicals is unclear. 相似文献
943.
The goal of this study was to determine the acute effects of permanent denervation on the length density of the capillary
network in rat slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles and the effect of short-lasting reinnervation
in slow muscle only. Denervation was performed by cutting the sciatic nerve. Both muscles were excised 2 weeks later. Reinnervation
was studied 4 weeks after nerve crush in SOL muscle only. Capillaries and muscle fibres were visualised by triple immunofluorescent
staining with antibodies against CD31 and laminin and with fluorescein-labelled Griffonia (Bandeira) simplicifolia lectin. A recently developed stereological approach allowing the estimation of the length of capillaries adjacent to each
individual fibre (Lcap/Lfib) was employed. Three-dimensional virtual test grids were applied to stacks of optical images captured with a confocal microscope
and their intersections with capillaries and muscle fibres were counted. Interrelationships among capillaries and muscle fibres
were demonstrated with maximum intensity projection of the acquired stacks of optical images. The course of capillaries in
EDL seemed to be parallel to the fibre axes, whereas in SOL, their preferential direction deviated from the fibre axes and
formed more cross-connections among neighbouring capillaries. Lcap/Lfib was clearly reduced in denervated SOL but remained unchanged in EDL, although the muscle fibres significantly atrophied in
both muscle types. When soleus muscle was reinnervated, capillary length per unit fibre length was completely restored. The
physiological background for the different responses of the capillary network in slow and fast muscle is discussed.
This study was supported by the Slovenian Research Agency and the Ministry of Education, Youth and Sport of the Czech Republic
(KONTAKT grant no. 19/2005). 相似文献
944.
Maćkowiak P Nogowski L Nowak KW 《Journal of receptor and signal transduction research》1999,19(1-4):283-292
The experiments were carried out on ovariectomized Wistar rats. Their livers were perfused with basic perfusion medium (BPM) or BPM supplemented with isoflavone genistein, insulin or combination of the two factors. The obtained results support the hypothesis that genistein influences the kinetics of insulin binding to cell membranes changing the number of insulin receptors and dissociation constant (Kd). BPM supplementation with genistein decreased number of high affinity insulin receptors (HAIR) both in livers treated and untreated with insulin. The amount of HAIR diminished significantly from 610 +/- 77 x 10(-15) (no genistein) to 238 +/- 72 x 10(-15) mol/mg of membrane protein (supplement of genistein). Similarly, genistein reduced slightly the amount of HAIR even when added together with insulin (372 +/- 59 x 10(-15) mol/mg) in comparison to rats perfused with medium containing insulin but not the isoflavone (421 +/- 46 x 10(-15) mol/mg). Simultaneously, genistein decreased significantly Kd for HAIR (perfusion with BPM--1.44 +/- 0.18 x 10(-9) mol/l; perfusion with BMP + genistein--0.83 +/- 0.20 x 10(-9) mol/l). Such effects of genistein during liver perfision did not take place when the liver membranes were in vitro incubated with this xenobiotic. 相似文献
945.
946.
Horvat A Momić T Petrović S Nikezić G Demajo M 《Physiological research / Academia Scientiarum Bohemoslovaca》2006,55(3):325-338
The effect of drugs from the class of cardiac (methyldigoxin, verapamil, propranolol), antiepileptic (carbamazepine), sedative (diazepam) and antihistaminic (promethazine) drugs on Na,K-ATPase activity of plasma membranes was studied in rat brain synaptosomes. Methyldigoxin in a concentration of 0.1 mmol/l inhibits enzyme activity by 80 %. Verapamil, propranolol and promethazine in concentrations of 20, 20 and 2 mmol/l respectively, entirely inhibit the ATPase activity. Carbamazepine and diazepam in concentrations of 0.02-60 mmol/l have no effect on the activity of this enzyme. According to the drug concentrations that inhibit 50 % of enzyme activity (IC(50)), the potency can be listed in the following order: methyldigoxin promethazine verapamil ? propranolol. From the inhibition of commercially available purified Na,K-ATPase isolated from porcine cerebral cortex in the presence of chosen drugs, as well as from kinetic studies on synaptosomal plasma membranes, it may be concluded that the drugs inhibit enzyme activity, partly by acting directly on the enzyme proteins. Propranolol, verapamil and promethazine inhibitions acted in an uncompetitive manner. The results suggest that these three drugs may contribute to neurological dysfunctions and indicate the necessity to take into consideration the side effects of the investigated drugs during the treatment of various pathological conditions. 相似文献
947.
Cystic cystitis is a separate form of urinary bladder inflammation, detected by cystoscopy in children with recurrent urinary infections. Cystoscopy is an invasive method, so the aim of this investigation was to determine the ultrasonographic characteristics of cystic cystitis and to assess the reliability of ultrasound in relation to cystoscopy in diagnosing cystic cystitis. The study included 115 girls with repeated urinary infections. Cystoscopy and ultrasonography was performed in all. According to the cystoscopic finding the subjects were divided into 4 groups. Lateral and posterior urinary bladder wall thickness was measured during ultrasonography. A statistically significant difference was found between all 4 groups, the method demonstrated a high degree of sensitivity (0.97) and specificity (0.91). Percentile calculations were determined for wall thickness. Ultrasonography can replace endoscopy in diagnosis and follow-up of cystic cystitis in children, with at least 50% fullness of the urinary bladder as a prerequisite. 相似文献
948.
Mesaros-Kanjski E Kontosić I Kusić Z Kaić-Rak A Daković N Kuser J Antonić K 《Collegium antropologicum》1999,23(2):729-736
A total of 1975 school-children on the island of Krk aged 7-19 years of life were included in this study. The purpose was to establish the goitre status and plasmatic level of vitamins A and E in the examined children with the enlarged thyroid gland. The goitre prevalence was 29.8%. The average plasmatic values of vitamins A and E in the children with enlarged thyroids were statistically significantly lower from the reference values. Mentioned goitre prevalence at the level of moderate and heavier endemic goitre speaks on behalf of alimentary iodine deficiency. But the goiter examinations suggested the idoine deficiency not to be the only etiological factor of goitre on the island of Krk. Lower average plasmatic values of vitamins A and E in the examined with the enlarged thyroids referred to this fact to a certain degree. 相似文献
949.
Glucuronoyl esterase is a novel carbohydrate esterase recently discovered in the cellulolytic system of the wood-rotting fungus
Schizophyllum commune on the basis of its ability to hydrolyze methyl ester of 4-O-methyl-d-glucuronic acid. This substrate was not fully corresponding to the anticipated function of the enzyme to hydrolyze esters
between xylan-bound 4-O-methyl-d-glucuronic acid and lignin alcohols occurring in plant cell walls. In this work we showed that the enzyme was capable of
hydrolyzing two synthetic compounds that mimic the ester linkages described in lignin-carbohydrate complexes, esters of 4-O-methyl-d-glucuronic and d-glucuronic acid with 3-(4-methoxyphenyl)propyl alcohol. A comparison of kinetics of hydrolysis of methyl and 3-(4-methoxyphenyl)propyl
esters indicated that the glucuronoyl esterase recognizes the uronic acid part of the substrates better than the alcohol type.
The catalytic efficiency of the enzyme was much higher with the ester of 4-O-methyl-d-glucuronic acid than with that of d-glucuronic acid. Examination of the action of glucuronoyl esterase on a series of methyl esters of 4-O-methyl-d-glucopyranuronosyl residues α-1,2-linked to xylose and several xylooligosaccharides suggested that the rate of deesterification
is independent of the character of the carbohydrate part glycosylated by the 4-O-methyl-d-glucuronic acid. 相似文献
950.
Horvat A Orlić T Banjac A Momić T Petrović S Demajo M 《General physiology and biophysics》2006,25(1):91-105
The in vitro effect of digoxin, verapamil, propranolol, carbamazepine, diazepam and promethazine were investigated on the ecto-ATPase activity of synaptosomal plasma membranes from the rat brain. ATP hydrolyzing activities of the enzyme were not affected by digoxin while the use of all other drugs resulted in significant and dose-dependent ihibition in ATP hydrolysis. According to values of IC(50) and K(iapp), the order of inhibitory potency of the drugs applied was: diazepam > promethazine > verapamil > propranolol > carbamazepine. Kinetic analysis of the nature of the ATPase inhibition revealed that it resulted from a direct action of drugs on the enzyme protein. The aim of the present study was to determine the potential neuromodulatory side effects of the drugs investigated. The results achieved indicated that all investigated drugs, except digoxin, may modulate neuronal activities via the purinergic receptors P2 by increasing extracellular concentrations of ATP as a consequence of inhibition of the ecto-ATPase activity. Our findings indicate that it may be useful to take into consideration the possible side effects of the investigated drugs, when they are used in treatment of different pathologies, particularly in the treatment of epilepsy by carbamazepine and diazepam. 相似文献