Studies on Hypokalemia Induced by Trimethyltin Chloride

Objectives To determine the possible relationship between plasma potassiumconcentration and severity of acute trimethyltin chloride (TMT) poisoning and to assess themechanism of TMT induced hypokalemia. Methods SD rats were treated with variousdosages of TMT (ip). All the indices were measured and analysed for determing theirpossible relations with plasma K+. Results With increase of dosage, the plasma K+ leveldropped rapidly, and deaths appeared more quickly. The LD50 of TMT (ip) was 14.7 mg/kgbw. In the low dosage group (10 mg/kgbw), the plasma K+ level dropped slowly with thelowest dosage on day 6 (4.85 mmol/L). It rose again on day 11 (5.06 mmol/L), and recoverdon day 28. The poisoning signs corresponded with decline of the span of K+ level. The plasmaNa+ level dropped half an hour after TMT treatment, but recovered 24 h later. In the highdosage group (46.4 mg/kgbw), the levels of plasma K+ and Na+ fell rapidly within half anhour (P<0.05), the intracellular potassium concentration of RBC did not decrerase obviously(P>0.05), the activities of Na+-K+-ATPase and Mg2+-ATPase in RBC membrane weredepressed remarkably (P<0.01, P<0.05, respectively), the plasma aldosterone concentrationsrose as high as tenfold (P<0.01), the arterial blood pH fell from 7.434 to 7.258 (P<0.01),pCO2 was raised from 29.62 to 45.33 mmHg (P<0.01). In the 24 h urine test, when rats weretreated with TMT (21.5 mg/kgbw, ip), urine volume, urinary potassium, sodium and chlorideincreased significantly in comparison with those in the controls (P<0.01). Conclusion TMTcould induce hypokalemia in SD rats. The available evidence suggests that TMT can induceacute renal leakage of potassium. At the same time, a significant rise of plasma aldosteronemay play an important role in promoting potassium leakage from kidney to result in severehypokalemia with inhaling acid-base abnormalities produced, which aggravate the poisoningsymptoms. In the end the rats would die of respiratory failure.

Guinea Pig Maximization Test for Trichloroethylene and Its Metabolites

Objectives To study the contact allergenic activities of trichloroethylene (TCE) and its three metabolites trichloroacetic acid, trichloroethanol and chloral hydrate. Methods A modified guinea pig maximization test (GPMT) was adopted. The skin sensitization (edema and erythema) was observed in trichloroethylene, trichloroacetic acid, trichloroethanol, chloral hydrate and 2,4-dinitrochlorobenzene. Results The allergenic rate of TCE, trichloroacetic acid and 2,4-dinitrochlorobenzene was 71.4%, 58.3% and 100.0% respectively, and that of trichloroethanol and chloral hydrate was 0%. The mean response score of TCE, trichloroacetic acid and 2,4-dinitrochlorobenzene was 2.3, 1.1, 6.0 respectively. The histopathological analysis also showed an induction of allergenic transfomation in guinea pig skin by both TCE and trichloroacetic acid. Conclusion TCE appears to be a strong allergen while trichloroacetic acid a moderate one. On the other hand, both trichloroethanol and chloral hydrate are weak sensitization potentials. Immunologic reaction induced by TCE might be postulated as the pathological process of this illness. Consequently, it is suggested that in the mechanism of Occupational Dermatitis Medicamentose-Like (ODML) induced by TCE, the chemical itself might be the main cause of allergy. As one of its metabolic products, trichloroacetic acid might be a subordinate factor.

Modulation of Isoflavones on Bone-nodule Formation in Rat Calvaria Osteoblasts in vitro

Objective To observe the effects of two main isoflavones, daidzein and genistein on the bone-nodule formation in rat calvaria osteoblasts in vitro. Methods Osteoblasts obtained from newborn Sprague-dawley rat calvarias were cultured for several generations. The second generation cells were cultured in Minimum Essential Medium supplemented with ascorbic acid and Na-beta-glycerophosphate for several days, in the presence of daidzein and genistein, with or without the estrogen receptor antagonist ICI 182780. Number of nodules was counted at the end of the incubation period (day 20) by staining with Alizarin Red S calcium stain. The release of osteocalcin, as a marker of osteoblast activity, was also determined on day 7 and day 12 during the incubation period. Results Compared with the control, the numbers of nodules were both increased by incubation with daidzein and genistein. 17β-estradiol was used as a positive control and proved to be a more effective inducer of the increase in bone-nodules formation than daidzein and genistein. The release of osteocalcin into culture media was also increased in the presence of daidzein and genistein, as well as 17β-estradiol on day 7 and day 12 (day 12 were higher). The estrogen receptor antagonist ICI 182780 completely blocked the genistein- and 17β-estradiol-induced increase of nodule numbers and osteocalcin release in osteoblasts. However, the effects induced by daidzein could not be inhibited by ICI 182780. Conclusion These findings suggest that geinistein can stimulate bone-nodule formation and increase the release of osteocalcin in rat osteoblasts. The effects, like those induced by 17β-estradiol, are mediated by the estrogen receptor dependent pathway. Daidzein also can stimulate bone-nodule formation and increase the release of osteocalcin in rat osteoblasts, but it is not, at least not merely, mediated by the estrogen receptor dependent pathway.

Differentiation of Mesenchymal Stem Cells Into Dopaminergic Neuron-like Cells in vitro

To explore the way to induce mesenchymal stem cells (MSCs) to differentiate into dopaminergic neurons in vitro. Methods MSCs were obtained from rat bone marrow, cultured and passaged. MSCs used in this experiment had multipotency, which was indirectly proved by being induced to differentiate into chondrocytes and adipocytes. MSCs were cultured in medium containing 0.5 mmol/L IBMX for 2 days. Then the medium was replaced with induction medium, which contained GDNF, IL-1β, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments. The surface markers of the differentiated neurons, such as NSE, nestin, MAP-2a, b and TH were detected by immunocytochemistry and Western blot after MSCs were cultured in induction medium for 7 days and 15 days. Results MSCs differentiated into neural progenitors and expressed nestin after MSCs were incubated with medium containing IBMX for 2 d. After the medium was replaced with induction medium containing many inducing agents, MSCs differentiated into neuron-like cells and dopaminergic neuron-like cells and expressed NSE, MAP-2a, b and TH. The percentage of NSE-positive cells, MAP-2a, b-positive cells and TH-positive cells was 30.032±2.489%, 41.580±5.101% and 34.958±5.534%, respectively after MSCs were induced in medium containing GDNF, IL-1β, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments for 15 days. Conclusion MSCs can differentiate into dopaminergic neuron-like cells and are a new cell source for the treatment of neurodegeneration diseases and have a great potential for wide application

Gene expression profiles of hepatocytes treated with La(NO_3)_3 of rare earth in rats

AIM: To compare the gene expression between La(NO3)3-exposed and control rats in vivo. METHODS: Rats were fed La(NO3)3 once daily at a dose of 20 mg/kg for one month by gavage. Gene expression of hepatocytes was detected using mRNA differential display (DD) technique and cDNA microarray and compared between treated and control groups. RESULTS: Six differentially expressed sequence tags were cloned by DD, of which five were up regulated and one was down regulated in treated rats. Two sequences were determined. One band was novel. The other shared 100% sequence homology with AU080263 Sugano mouse brain mncb Mus musculus cDNA clone MNCb-5435 5'. With DNA microarray, 136 differentially expressed genes were identified including 131 over-expressed genes and 5 under-expressed genes. Most of these differentially expressed genes were cell signal and transmission genes, genes associated with metabolism, protein translation and synthesis. CONCLUSION: La(NO3)3 could change the expression levels of some kinds of genes. Further analysis of the differentially expressed genes would be helpful for understanding the wide biological effect spectrum of rare earth elements.

Antimutagenicity of Propolis Against Some 0Mutagens in vivo and in vitro

Objective To evaluate the antimutagenicity of propolis in vivo and in vitro. Methods Salmonella typhimurium strains TA98 and TA100 were used as a test model in vitro against a direct mutagen DMC and an indirect mutagen 2AF with or without S9 mix, and MN formation of mice bone marrow cell and CAs induction of mice testicle cell were applied as a test model in vivo against two mutagens CP and MMC. Results The present study clearly demonstrated that propolis could inhibit mutagenicity of both DMC and 2AF directly in a dose-dependent manner, and significant antimutagenic effects (P<0.05) were obtained in TA98 strain at 2000 and 3000 mg/plate. It also could inhibit mutagenicity of both DMC and 2AF to TA98 strain in a dose-dependent manner, with significant antimutagenic effects (P<0.05) appeared at 1000, 2000, and 3000 mg/plate. The results of antimutagenicity test in vivo revealed that propolis could inhibit MN formation significantly (P<0.05) at the doses of 45.0 and 135.0 mg/kg b. w., and decrease the frequency of chromosome aberrants and chromosome aberrant cells significantly (P<0.05) only at the dose of 135.0 mg/kg b. w. Conclusion The propolis is a good inhibitor for mutagencity of DMC and 2AF in vitro, as well as for CP and MMC in vivo.

Lead Can Inhibit NMDA-,K^+-,QA/KA-Induced Increases in Intracellular Free Ca^(2+) in Cultured Rat Hippocampal Neurons

Objective To examine the effects of Pb2+ on N-methyl-D-aspartate (NMDA)-, K+- and quisqualate(QA)/kainite(KA)-induced increases in intracellular free calcium concentration ([Ca2+],) in cultured fetal rat hippocampal neurons in order to explain the cognitive and learning deficits produced by this heavy metal. Methods Laser scanning confocal microscopy was used. Results The results clearly demonstrated that adding Pb2+ before or after NMDA/glycine stimulation selectively inhibited the stimulated increases in [Ca2+], in a concentration-dependent manner. In contrast, Pb2+ treatment did not markedly affect increases in [Ca2+], induced by an admixture of QA and KA. The minimal inhibitory effect of Pb2+ occurred at 1 μmol/L, and more than seventy percent abolition of the NMDA-stimulated increase in [Ca2+]; was observed at 100 Jμmoll/L Pb2+. Evaluation of Pb2+-induced increase in [Ca2+], response to elevating extracellular concentrations of NMDA, glycine or calcium revealed that Pb2+ was a noncompetitive antagonist of both NMDA and glycine, and a competitive antagonist of Ca2+ at NMDA receptor channels. In addition. Pb2+ inhibited depolarization-evoked increases in [Ca2+], mediated by K+ stimulation(30μmol/L). indicating that Pb2+ also depressed the voltage-dependent calcium channels. Also, the results showed that Pb2+ appeared to be able to elevate the resting levels of [Ca2+|, in cultured neurons, implying a reason for Pb2+-enhanced spontaneous release of several neurotransmitters reported in several previous studies. Conclusion Lead can inhibit NMDA-. K+-, QA/KA-jnduced increases in intracellular [Ca2+], in cultured hippocampal neurons.

Chromium(VI)-induced Production of Reactive OxygenSpecies, Change of Plasma Membrane Potential and Dissipation of Mitochondria Membrane Potential in Chinese Hamster Lung Cell Cultures

Objective\ To examine whether Reactive Oxygen Species (ROS) is generated, and whether plasma membrane potential and mitochondrial membrane potential are depolarized in Chinese Hamster Lung (CHL) cell lines exposed to Cr (VI). Methods\ CHL cells were incubated with Cr(VI) at 10 μmol/L, 2.5 μmol/L, 0.65 μmol/L for 3 and 6 hours, respectively. The production of ROS was performed by using 2,7_dichlorofluorescin diacetate; The changes in plasma membrane potential were estimated using fluorescent cationic dye DiBAC4; And the changes in mitochondria membrane potential were estimated using fluorescent dye Rhodamine 123. Results\ The ROS levels in CHL cells increased in all treated groups compared with the control group (P<0.01); The plasma membrane potential and mitochondrial membrane potential in CHL cells dissipated after incubated with Cr(VI) at 10 μmol/L for 3 hours and 6 hours (P<0.01), at 2.5 μmol/L for 6 hours (P<0.01 or 0 05). Conclusion\ Cr(VI) causes the dissipation of plasma membrane potential and mitochondrial membrane potential in CHL cell cultures, and Cr(VI)_induced ROS may play a role in the injuries.

Potentiation of glutamate release caused by delta—methrin and the possible mechanism associated with carbon monoxide pathway and protein kinase C

The acute neurotoxicity of delta-methrin is thought to be associated with the release of grutamate from synaptosomes in brain.However,the mechanism how delta-methrin enhances the glutamate release has still not been elucidated.Here we report that both carbon monoxide(CO) and the activator of protein kinase C(PKC),similarly to delta-methrin,potentiate the Ca^2+-dependent glutamate release from rat cerebral cortical synaptosomes,otherwise,the release of glutamate is inhibited by zinc proporphyrin-9(ZnPP-9) and inhibitors of PKC or of protein kinase G(PKG).In addition,the inhibitors of ZnPP-9 PKC and PKG seem to weaken the enhancement of glutamate releas caused by delta-methrin.So,we conclude that CO signal transduction pathway and PKC mediate the glutamate release from synptosomes by delta-methrin.

Therapeutic effect of ifenprodil,a NMDA receptor antagonist,on drug dependence

Although drug dependence has been treated by the adonist-therapy,the specific drug therapy for drug dependence has not been established.Ifenprodil is consibdred to specifically block the NMDA receptor consisted of NR1/NR2B subunits without undesirable adverse reactions,such as psychotomimetic action and psychological dependence,while ketamine and MK-801 can block both NMDA receptors consisted of NR1/NR2A and NR1/NR2B subunits with the undesirable adverse reactions.In the present study,we designed to examine the effect of ifenprodil on drug dependence in rodents.Pretreatment with ifenprodil suppressed the expression of withdrawal signs in morphine-, diazepam-and alcohol-dependent rats and mics.Rewarding effects of morphine,methamphetamine and cocaine as well as physical dependence,were suppressed by pretreatment with ifenprodil in rats and mice.These results suggest that ifenprodil be useful in treating drug dependence.

The Protective Effects of N-Acetylcysteine on Exogenous Hydrogen Peroxide and Endogenous Superoxide Anion-induced DNA Strand Breakage in Human Spermatozoa

Objective To explore the protective effects of N Acetylcysteine (NAC) on exogenous hydrogen peroxide and endogenous superoxide anion induced DNA strand breakage in human spermatozoa by using the single cell gel electropherosis (SCGE) Methods Sperm cells were exposed to 0.5 mmol/L of H 2O 2 or 5.0 mmol/L of β NADPH with or without 0.1, 0.5, 1.0 mmol/L of NAC. The percentage of sperm comet cells and the comet tail lengths were measured in the treated sperm cells by using SCGE. Results Both percentage of comet sperm nuclei and mean tail length in sperm cells exposed to 0.5 mmol/L hydrogen peroxide with different concentrations of NAC decrease significantly in a dose dependent manner as compared with sperm cells exposed to H 2O 2 without NAC or catalase. Although mean tail length in sperm cells exposed to 5.0 mmol/L of β NADPH with different concentrations of NAC decreases significantly compared with sperm cells exposed to β NADPH without NAC or SOD, there were no significant differences on the percentage of sperm comet cells between sperm cells exposed to 5.0 mmol/L of β NADPH with different concentrations of NAC and sperm cells exposed to 5.0 mmol/L of β NADPH without NAC. Conclusion NAC has a protective effect on exogenous hydrogen peroxide induced DNA damage, while protective effect of NAC against O - 2 induced DNA strand breakage is significant but very weak.

A teratology assessment of nimesulide in rats

Nimesulide(NIM) was administered by gavage to Sprague-Dawley(SD) rats from day 6 to day 15 of getation,at level of 15,30 and 100mg·kg^-1·d^-1.Maternal weight gain was depressed,and the incidences of fetal absorption and lethal fetal were couned in all groups receiving NIM.Malformation of internal organs,appearance of fetuses and retardation of fetal development were not oberved.NIM had little effect on skeletal development,except increasing width of fontanel at high dose(100mg·kg^-1).NIM produced low levels of embryotoxicity and fetotoxicity.But no teratogenic effects of NIM were observed in SD rats.

Study on Peripheral Blood Lymphocytes ChromosomeAbnormality of People Exposed to Cadmium in Environment

Chromosome aberration (CA) and micmnucleus (MN) tests were appied to investigate Peripheral blood lymphocytes in 56 people environmentally exposed to cadwhum (Cd) for a period up to 30years, and in 10 unexposed People as controls. As indicator of body-load of Cd, urineq Cd (UCd)concentrations were measured simultaneously. The People in polluted villages were divided into four groups according to vallous levels of UCd concentrations: ~ 2 .5, 2 .5 ~, 5 .0 ~, 10.0 ~ (μg/l).There was significant difference in MN rates between the exposed and control groups (3 .47, 5 .06,8.06, 12 .75‰ for the exposed groups respectively, and 3. 10‰ for the controls), and significant correlation between MN rates and UCd was observed. Although no markesd difference in CA rates was noted between UCd 5 .0 ~ and 10 .0 ~ groups, there was significant difference in CA rates between the exposed and control groups (3. 07,5. 21, 7. 21, 8. 50% for exposed groups respectively, and2 .33% for the controls) and significant correlation between CA rates and UCd. CA was presented mainly in the form of chromatid and chromosome gaps and breaks. Together with our another study 'An Investigation on Human Health Effects by Envimnmental Cadmium Pollution', the results suggest that Cd may injure human chromosomes and that the damage appears to be concentrated on cytogenetic material and may happen earlier than renal disfunction

Protective Effect of Vitamin E on Liver Damage Induced by 2-Chloro-1, 3-butadiene

The present study was performed to determine the influence of lipid peroxidation and perturbance of Ca2+ homeostasis on liver damage induced by 2-chloro-1, 3-butadiene (CBD) and the protective effects of vitamin E in Wistar rats. Animals were given intraperitoneally different doses (8,40 or 200 mg·kg-1 daily) of CBD for 21 days, and the following dose-dependent events were observed: liver damage, significant increase in liver lipid peroxides, and decreases in activities of erythrocytic glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). The pretreatment of rats with vitamin E (po 150 mg·kg-1) before administering CBD (iP 60 mg·kg-1 ) daily for 21 days prevented the following CBD-induced changes, the increase in serum cholylglycine (CG), hepatic LP, hepatic mitochondrion LP, hepatic oxidized glutathione (GSSG) (while the significant increase of reduced glutathione (GSH) was not affected) and the decrease in activities of erythrocytic SOD and hepatic mitochondrial calcium sequestration. These results suggest that lipid peroxidation and perturbance of Ca2+ homeostasis appear to contribute to the hepatotoxicity of CBD, and vitamin E might prevent the liver damage induced by CBD. The decrease in activities of GSH-Px and SOD in erythrocytes might be used as biomarkers for adverse effects of CBD on defense system against lipid peroxidation.

Effect of Low Benzene Exposure on Neurobehavioral Function, AChE in Blood and Brain and Bone Marrow Picture in Mice

The purpose of this study was to examine the effect of low level benzene exposure on neurobehavioral functions, AChE in blood and brain, bone marrow picture in Kunming mice. Forty adult Kunming male mice were divided into 4 groups. They were exposed to 12.52, 3.13, 0.78 and 0 ppm benzene for 2 h.d-1 for 30 d. Central nervous system (CNS) function was inhibited by 12.52 ppm and excited by 0.78 ppm benzene exposure, but irregularly affected by 3.13 ppm. AChE in blood and brain was decreased in 12.52, 3.13 ppm group. The weight of liver to body weight ratios in 12.52 ppm group was higher than those of control group significantly. Bone marrow picture revealed inhibited proliferation of white and red cell systems, especially in 12.52 ppm group, consisting of decrease of percentage of myeloblast, premyelocytes, myelocytes, erythroblasts and megakaryocytes, especially in 12.52 ppm group.

Study of the Relationship between the Hepatotoxicity and Free Radical Induced by 1,1,2-Trichloroethane and 1,1,1-Trichloroethane in Rat

The hepatotoxicity and the relationship between the hepatotoxicity and free radical induced by 1,1,2-trichloroethane (1,1,2-TCE) and 1,1,1-trichloroethane (1,1,1-TCE) were studied by whole animals test and the isolated perfused rat liver test. Enzymatic parameters measured during the test included the assay of levels of glutamic pyruvic transaminase (GPT), sorbital dehydrogenase (SDH) and glutamate dehydrogenase (GDH). The observation of the pathologic changes of the liver by the light microscope and the measurement of the relative total free radical concentration in the liver were also made. The results showed that 1,1,2-TCE caused definite pathologic changes of rat liver. It led to much higher values for GPT, SDH and GDH both in serum and perfusate than 1,1,1-TCE did (P<0.01). The concentration of perfusate K+ caused by 1,1,2-TCE was higher than that by 1,1,1 -TCE (P < 0.01). The value of the relative total free radical concentration induced by 1,1,2-TCE was also greater than that by 1,1,1-TCE (P<0.05). The results suggested that the hepatotoxicity of 1,1,2-TCE was stronger than that of 1,1,1-TCE. The free radical concentration was increased proportionally to the increase of the hepatotoxicity of 1,1,2-TCE and 1,1,1 -TCE. It appeared that free radical may play an important role in the mechanism of the hepatic injury induced by 1,1,2-TCE.