2001 Vol. 14, No. 4
Objective To investigate functional homooligomeric GABAρ1 receptors expressed in Xenopus oocytes and the modulation of divalent cations. Methods GABAρ1 cDNA from human retina was transcribed in vitro to obtain sense ρ1 mRNA, which was microinjected into Xenopus oocytes. Two-electrodes voltage clamp technique was performed to record GABA-induced currents. Results Expressed receptors were found to have similar properties to GABAC receptors characterized in the retina. Cl-currents induced by GABA were blocked by picrotoxin instead of bicuculline. GABA-induced currents reversed at -19±2.5 mV, and EC50 was 3.3 μmol/L. Zn+ + modulated GABA-induced currents with an IC50=9.6 μ mol/L. Ni+ +, Cu+ + and Cd+ + inhibited GABA ρ1 obviously, too. Their rank order of potency was Zn+ +>Ni+ +>Cu+ +>Cd+ +. Conclusion Zinc(10 μmol/L) inhibited GABA-induced currents in a competitive manner, and its action was sensitive to extracellular pH. Site-directed mutagenesis revealed that substitution of a single histidine residue (H44 and H48) failed to affect zinc sensitivity.
Objective To investigate the molecular regulation of G1 arrest of mouse thymocytes induced by ionizing radiation. Methods Cell cycle was analyzed by flow cytometry (FCM) following staining of cells with proidium iodide. Fluorescent staining and flow cytometry analysis were employed for measurement of protein expression. Results It was demonstrated that G1 phase of mouse thymocytes increased significantly at 12h after whole body irradiation (WBI) with the doses of 0.5, 1.0 and 2.0 Gy, and at 24h following 2.0Gy exposure, measured by FCM. In the time course experiment, it was found that G1 phase of thymocytes increased significantly at 4h, reached a peak level at 24h and came down toward 48h after WBI with 2.0Gy X-rays. The results also showed that after 2.0Gy exposure, the expression of proteins in mouse thymocytes increased significantlty from 1h to 8h for p53, for p21 from 4h to 48h, and for MDM2 at 4h and 8h, measured by FCM. But no change was found for GADD45 protein expression. Conclusion These results suggest that G1 arrest could be induced by a single dose of 0.5 Gy, 1.0Gy or 2.0Gy, and its molecular control might be established through the p53-p21 pathway.
Objective Child Malnutrition has been defined or described in many ways. To summarize the common points, child malnutrition may be defined as a pathological state resulting from inadequate nutrition, including undernutrition (protein- energy malnutrition) due to insufficient intake of energy and other nutrients; overnutrition (overweight and obesity) due to excessive consumption of energy and other nutrients; deficiency diseases due to insufficient intake of one or more specific nutrients such as vitamins or minerals.
In the assessment of child malnutrition, a large number of measures are available. Among these measuring methods, Z-score, growth charts, weight-for-length index (WLI), height standard weight, body mass index, skin fold thickness and clinical grading diagnosis standard for child malnutrition are selected for discussion. The same set of anthropometry data of a group of preschool children was analyzed by using different methods. The results showed that it was very difficult to determine the nutritional state of children using a single index. For a given group of children, Z-score method is recommended to observe their height, weight and weight for height at the same time in order to have a comprehensive understanding.
Objective To express human vascular endothelial growth factor receptor Flt-1 extracellular domain 1-3 loop cDNA in Pichia. Pastroris, and to purify the expressed product and detect its biological activity. Methods By inserting human Flt-1 (1-3 loop) cDNA coding 316 amino acid residues into Pichia pastoris expression vector pPIC9K containing AOX1 promoter and the sequences of α secreting signal peptides, a recombinant expression plasmid pPIC9K/Flt-1 (1-3) was constructed and transformed to yeast host strain GS115, then His+ Muts phenotype transformant was screened out and cultured in flasks, and Flt-1 (1-3) was expressed under the induction of 1% methanol. Results SDS-PAGE showed that after being induced with 1% methanol for 4d, the expressed product existed in supernatant in the form of soluble molecule and contained 60% of total protein expressed. Western blot showed good antigenicity and specificity of expressed product. After being purified by CM-Sepharose FF and Sephacryl S-100 chromatography, the purity of the expressed product reached above 90%. Biological assay proved that the expressed product could bind to hVEGF165 and inhibit the proliferation of HUVEC stimulated by hVEGF165. Conclusion Human vascular endothelial growth factor receptor Flt-1 extracellular domain 1-3 loop was successfully expressed. The study lays a foundation for further application of the expressed product in the treatment of vasoformation related diseases, such as tumor and diabetic retinopathy.
Objective To express human vascular endothelial growth factor (hVEGF165) cDNA in Pichia pastroris, purify the expressed product and detect the biological activity of it. Methods By inserting hVEGF165 cDNA coding 165 amino acid residues into Pichia pastoris expression vector pPIC9K containing AOX1 promoter and the sequences of α secreting signal peptides, a recombinant expression plasmid pPIC9K/hVEGF165 was constructed and transformed to yeast host strain KM71, then multiple-copy insert transformants were screened out and cultured in flasks, and hVEGF165 was expressed under the induction of 1% methanol. Results SDS-PAGE showed that after being induced with 1% methanol for 4d, the expressed product existed in supernatant in the form of soluble molecule and contained 60% of total protein expressed. Western blot showed good antigenicity and specificity of expressed product. After being purified by Heparin-Sepharose CL6B affinity chromatography, the purity of expressed product reached above 90%. Biological assays proved that the expressed product could stimulate the proliferation of HUVEC. Conclusion hVEGF165 was successfully expressed. The study opened up a wide prospect for the application of VEGF165 in the prevention and treatment of ischemic heart disease and other tissue ischemic diseases such as secondary arterial occlusion in limbs.
2001, 14(4): 312-317.
Objective To study effects of cadmium on rat sperm motility evaluated with computer assisted sperm analysis. Methods Different doses of cadmium chloride (0.2,0.4,0.8mg Cd/kg BW) were administrated ip to adult male Sprague-Dawley rats. Control animals received the same volume of 0.9% NaCl solution. After 7 days, the rats were sacrificed with their testes removed. A part of one testis was used for testicular sperm head counts and daily sperm production observation. The motility of spermatozoa obtained from cauda epididymides using the “diffusion”method was measured by computer assisted sperm analysis(CASA). Results The sperm head counts and daily sperm production decreased significantly in the high dose group. The motility of spermatozoa in the middle dose group was reduced significantly. No motile sperm was found in the high dose group. The results suggest that germinal epithelium was impaired irreversibly in a short time to produce toxic effects on spermatogenesis at high cadmium doses. Conclusion Cadmium may reduce sperm motility at a dose far below the dose affecting sperm production at this time point. The motility of sperm is an early and sensitive endpoint for the assessment of cadmium toxicity on male reproduction.
Objective Based on the data collected in the 1992 national nutrition survey in China, the food consumption and nutrients intake were calculated, and the consumption of some micronutrients was evaluated. Method Dietary data were obtained by using a three days' inventory change plus food weighing in combination with 24 hours recall method for three consecutive days. The food consumption and nutrients intake were calculated in accordance with the Chinese food composition table. The consumption of some micronutrients was evaluated in reference to the Chinese RDAs. Results The average intakes of niacin, ascorbic acid and vitamin E were sufficient, whereas that of zinc, selenium and thiamin were between 80% and 90% RDAs. The consumption of calcium, retinol equivalent and riboflavin was low compared with the Chinese RDAs. Calcium was the most insufficient nutrient in Chinese diet. Conclusion Food fortification seems necessary for improving the nutritional status of some micronutrients in China.
2001, 14(4): 325-332.
Objective Trichloroethylene (TCE) is one of the most potent organic unsaturated solvents being used in dry cleaning, metal degreasing, thinner for paints varnishes and electroplating, etc. and has been reported to be a hepatotoxicant through oral and dermal exposure. However, its inhalation toxicity data is very limited in the literature due to the fact that the exposure levels associated with these effects were usually not reported. Hence, inhalation toxicity study was carried out for hepatotoxic studies. Method Inhalation toxicity studies was carried out by exposing rats to TCE for 8, 12 and 24 weeks in a dynamically operated whole body inhalation chamber. Sham treated control rats were exposed to compressed air in the inhalation chamber for the same period. Results Significant increase in liver weight (liver enlargement) appearance of necrotic lesions with fatty changes and marked necrosis were observed after longer duration (12 and 24 weeks) of TCE exposure. The lysosomal rupture resulted in increased activity of acid and alkaline phosphatase alongwith reduced glutathione content and total increased sulfhydryl content in liver tissue. Conclusion TCE exposure through Inhalation route induces hepatotoxicity in terms of marked necrosis with fatty changes and by modulating the lysosomal enzymes.
Objective The pulmonary toxicity of a commercially available formulated preparation of Fenvalerate (Fen), a synthetic pyrethroid has been studied in rats following subchronic nose only inhalation exposure route. Method Adult male rats were exposed to Fen for 4h/day, 5 days a week for 90 days by using Flow Past Dynamic Nose only Inhalation Chamber. Results Fen exposed rats showed a significant increase in enzymatic activities of lactate dehydrogenase (LDH), acid phosphatase (ACP), alkaline phosphatase (ALP) and γ-glutamyl transferase (γ-GT) which are considered as biochemical indicators of pulmonary damage. The concomitant histopathological examination of Fen exposed rats' lung revealed inflammatory changes viz., influx of mononuclear cells admixed with a few giant cells in alveolar lumen, hypetrophied bronchiolar and alveolar epithelial lining cells and presence of edematous fluid in alveolar lumen alongwith congested parenchymatous blood vessels. Conclusion These results for the first time indicate the pulmonary toxic effects of a commonly used formulated Fen preparation by using rat model and nose only inhalation as the route of exposure.
Objective The pooled results of four large-scale clinical trials of antihypertensive treatments carried out in China were assessed, with an overall study population of 10,457 patients. Methods The fixed effect model was used for data analysis. Results A pooled analysis at the individual level showed that the average time of treatment was 3.4 years, after which an average reduction in blood pressure of 9/4 mmHg was found. The meta-analysis showed that stroke was reduced by 36% (95% CI 25%-46%, P<0.001), cardiovascular death and total deaths were reduced by 22% and 20% respectively (P<0.05) and total cardiovascular events were significantly reduced by 33% (P<0.001). However, the reduction in coronary heart disease (CHD) was much smaller and was not statistically significant (P>0.05), whereas the significant reduction in stroke was epidemiologically expected. Conclusion The benefit of antihypertensive treatment obtained was mostly due to a reduction in the incidence of stroke.
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