2004 Vol. 17, No. 1

Select articles
Differentiation of Rat Neural Stem Cells and Its Relationship With Environment
2004, 17(1): 1-7.
Objective To explore the differentiation fates of rat neural stem cells (NSCs) in differenten vironmental conditions. Methods NSCs derived from 16-day-old rat embryo were proliferated in vitro and implanted into the brain of rats with intra-cerebral hemorrhage. At the same time some NSCs were co-culturedin vitro with Schwann cells derived from newborn rats. MAP-2, GFAP and Ga1C (which are the specific markers of neural cells, astrocytes and oligodendrocytes respectively),BrdU and β-tubulin were detected by immunohistochemical and immunofluorescent methods.Results BrdU positive cells that were implanted into the brain distributed around the hemorrhagic area. The majority of them were GFAP positive astrocytes while a few of them were β-tubulin positive neural cells or GalC positive oligodendrocytes. After being co-cultured with Schwann cellsin vitro,NSCs are predominately shown β-tubulin and MAP-2 positive, and only a minority of them were GFAP or GalC positive. Conclusions The hemorrhagic environment in vivo induces NSCs to differentiate mainly into astrocytes while co-culture with Schwann cells in vitro induce the majority of NSCs to differentiate into neural cells.
Dynamic Analyses of PrP and PrPsc in Brain Tissues of Golden Hamsters Infected With Scraple Strain 263K Revealed Various PrP Forms
2004, 17(1): 8-20.
Objective To expatiate dynamic changes in hamsters infected with scrapie strain 263K, to observe the presence and aggravation of various forms of PrP and PrPSc during incubation period, and to probe primarily the relationship between the onset of clinic manifestations and the presence of different PrPSc forms. Methods Hamster-adapted scrapie strain 263K was intracerebrally inoculated into hamsters. Different forms of PrP and PrPSc were monitored dynamically by Western blot and immuno-histochemical assays. The presence of scrapie-associated fibril (SAF) was assayedby electron microscopy analysis (EM) and immuno-golden EM. Results PrPSc was initiallydetected in the brain tissues of the animals in 20 days post-inoculation by immunohistochemistry and 40 days with Western blot. Quantitative evaluations revealed that the amounts of PrP and PrPSc inbrain tissues increased along with the incubation. Several high and low molecular masses of PrP wereseen in the brains of the long-life span infected animals. Deglycosylation assays identified that the truncated PrP in the infected brains showed similar glycosylation patterns as the full-length PrP. The presence of short fragments was seemed to relate with the onset of clinical conditions. Conclusion These results indicate that infectious agents exist and accumulate in central nerve system prior to the onset of the illness. Various molecular patterns of PrPSc may indwell in brain tissues during the infection.
Microbial Degradation of Quinoline:Kinetics Study With Burkholderia picekttii
2004, 17(1): 21-26.
Objective To investigate the kinetics of quinoline biodegradation by Burkholderia pickttii, a Gram negative rod-shaped aerobe, isolated in our laboratory. Methods HPLC (Hewlett-Packard model 5050 with an UV detector) was used for the analysis of quinoline concentration. GC/MS method was used to identify the intermediate metabolites of quinoline degradation. Results The biodegradation of quinoline was inhibited by quinoline at a high concentration, and the degradation process could be described by the Haldane model. The kinetic parameters based on Haldane substrate inhibition were evaluated. The values were vmax= 0.44 h-1, Ks=166.7 mg/L, Ki= 650 mg/L, respectively.The quinoline concentration to avoid substrate inhibition was inferred theoretically and determined to be 329 mg/L. Conclusion The biodegradation of quinoline conforms to the Haldane inhibition model and the main intermediate metabolite of quinoline biodegradation is 2-hydroxy-quinoline.
Chelation in Metal Intoxication XLVI:Synthesis of Some α-Mercapto-β-Substituted Aryl Acrylic Acids and Their In vitro Cadmium Chelating Ability
2004, 17(1): 27-32.
Objective To synthesize some new α-mercapto-β-substituted aryl acrylic acids, characterize them and investigate their in vitro cadmium chelating ability. Methods Six α-mercapto-β-substituted aryl acrylic acids were prepared by the alkaline hydrolysis of 5-(aryl methylene)rhodanines, obtained from the condensation of substituted aldehydes and rhodanine following the reported procedure. The new compounds were characterized by elemental analysis, infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy. The liver and kidney from cadmium chloride pre-administered rats were homogenized and their nuclear mitochondrial fraction (NMF) and supernatant cytosol fraction (SCF) were separated. A measured volume of each fraction was dialyzed separately using "dialysis sack" against buffered-KCl medium containing a compound in the final concentration of 1×10-3 mol/L for 3 h at 37℃C. The whole content of "sack" was subjected to cadmiumestimation following digestion with conc. Nitric acid was detected using flame atomic absorption spectrometer. Results The in vitro screening showed that α-mercapto-β-(p-methoxyphenyl)acrylic acid (compound 2) and α-mercapto-β-(m-methoxy, p-hydroxyphenyl) acrylic acid (compound 4) were more effective than α-mercapto-β-thienyl acrylic acid (compound 1) and α-mercapto-β-(p-dimethylaminophenyl) acrylic acid (compound 3) in mobilizing cadmium as their dialyzable chelates. The presence of a methoxy group on the phenyl moiety (compounds 2 and 4) increases the metal chelating ability of mercapto acrylic acids. Conclusions Compounds 2 and 4 seem to have accessibility to the cellular system and capability of chelating-out the intracellularly bound cadmium.
ROS-related Enzyme Expressions in Endothelial Cells Regulated by Tea Polyphenols
2004, 17(1): 33-39.
Objective Elevation of reactive oxygen species (ROS), especially the level of superoxide is a key event in many forms of cardiovascular diseases. To study the mechanism of tea polyphenols against cardiovascular diseases, we observed the expressions of ROS-related enzymes in endothelial cells. Methods Tea polyphenols were co-incubated with bovine carotid artery endothelial cells (BCAECs) in vitro and intracellular NADPH oxidase subunits p22phox and p67phox, SOD-1, and catalase protein were detected using Western blot method. Results Tea polyphenols of 0.4 μg/mL and 4.0 μg/mL (from either green tea or black tea) down-regulated NADPH oxidase p22phox and p67phox expressions in a dose-negative manner (P<0.05), and up-regulated the expressions of catalase (P<0.05). Conclusions Tea polyphenols regulate the enzymes involved in ROS production and elimination in endothelial cells, and may be beneficial to the prevention of endothelial cell dysfunction and the development of cardiovascular diseases.
Radiation-induced Bystander Effect in Immune Response
2004, 17(1): 40-46.
Objective Since most reports on bystander effect have been only concerned with radiation-induced damage, the present paper aimed at disclosing whether low dose radiation could induce a stimulatory or beneficial bystander effect. Methods A co-culture system containing irradiated antigen presenting cells (J774A.1) and unirradiated T lymphocytes (EL-4) was established to observe the effect of J774A.1 cells exposed to both low and high doses of X-rays on the unirradiated EL-4 cells. Incorporation of 3H-TdR was used to assess the proliferation of the EL-4 cells,expression of CD80/86 and CD48 on J774A.1 cells was measured with immunohistochemistry and flow cytometry, respectively. NO release from J774A.1 cells was estimated with nitrate reduction method. Results Low dose-irradiated J774A.1 cells could stimulate the proliferation of the unirradiated EL-4 cells while the high dose-irradiated J774A.1 cells exerted an inhibitory effect on the proliferation of the unirradiated EL-4 cells. Preliminary mechanistic studies illustrated that the differential changes in CD48 expression and NO production by the irradiated J774A.1 cells after high and low dose radiation might be important factors underlying the differential bystander effect elicited by different doses of radiation. Conclsion Stimulatory bystander effect can be induced in immune cells by low dose radiation.
Endosulfan-mediated Biochemical Changes in the Freshwater Fish Clarias batrachus
2004, 17(1): 47-56.
Objective Endosulfan is an extremely toxic organochlorine pesticide to aquatic organisms which might be hampering fish health through impairment of metabolism sometimes leading to death.So an experimental protocol was designed to look at endosulfan effects on a number of selected biochemical endpoints as well as to develop a mechanistic understanding of biochemical effects of endosulfan in freshwater fish. Methods The adult freshwater catfish Clarias batrachus were collected and acclimatized to laboratory condition for two weeks prior to experimentation. The toxicity bioassay test of commercial grade endosulfan (35% EC) was conducted for 21 days to determine its initial lethal concentration. The fish were exposed to sublethal concentration of endosulfan (0.06 mg/L) for 21 days. Pesticide - withdrawal experiments were also performed to study recovery. Protein synthesis inhibitors were injected to know the possible mechanism of recovery. The specimens of C. batrachus were sacrificed and brain, liver and caudal white skeletal muscle were removed. Tissues were homogenized and fractions were obtained by differential centrifugation. The activities of citrate synthase (CS), glucose 6-phosphate dehydrogenase (G6-PDH) and lactate dehydrogease (LDH) were assayed spectrophotometrically. Similarly, DNA, RNA and protein content were measured as per standard procedure. Results The exposure of sublethal concentration of endosulfan decreased the activity of citrate synthase (CS) and glucose 6-phosphate dehydrogenase (G6-PDH) in the brain, liver and skeletal muscle of the freshwater catfish, C. batrachus. The brain lactate dehydrogenase (LDH) activity was also reduced in response to endosulfan toxicity. The maximum reduction in activities of these enzyme was 34%-43%. Withdrawal of endosulfan restored the enzyme activity to control level in all the three tissues. The recovery in enzyme activity appears to be due to dissociation of endosulfan or its metabolite(s) from the enzyme molecules and/or fresh synthesis of enzymes. The treatment of actinomycin D or cycloheximide partially inhibited the withdrawal-dependent increase in enzyme activity. This substantiates de novo synthesis of enzyme during recovery period. Since the reduction in enzyme acfvity was more pronounced in response to actinomycin D, endosulfan might be inhibiting the transcription process. But endosulfan did not produce any significant effect on DNA content and RNA/DNA. However, the RNA and protein contents of brain, liver and skeletal muscle decreased significantiy in tissues. The maximum decrease in RNA and protein was approximately 30%-37%. Withdrawal of endosulfan from the medium for 21 days restored the RNA, and protein contents nearly to their control levels. The treatment of actinomycin D or cycloheximide partially inhibited the withdrawal-dependent increase in these macromolecular contents. This effect was more pronounced in case of actinomycin D which again supports the possibility of endosulfan-induced inhibition at transcription level. Conclusion The present study suggests endosulfan-induced impairment of metabolism in fish, which appeared to be due to inhibition of transcription at some unknown points.
Polymorphism of Methionine Synthase Gene in Nuclear Families of Congenital Heart Disease
2004, 17(1): 57-64.
Objective To investgate the relation of methionine synthase (MS) gene variation with congenital heart disease (CHD) phenotype. Methods One hundred and ninety three CHD patients (94 males and 99 females) and their biological parents (nuclear families) in Liaoning Province were selected as the case group, and another 104 normal persons (60 males and 44 females) and their parents without family history of birth defects as the control group. For all subjects the polymorphism of MS gene A2756G locus was examined by PCR-RFLP method. Results In offspring of the control group the frequencies of MS genotype (+/-) and allele (+) were 10.7% and 5.3%, without existence of homozygote. The MS genotype distribution and allele frequencies of CHD patients and their mothers were not significantly different from the control (P > 0.05). The frequency of allele (+)in case fathers (5.0 %) was apparently lower than that in the control (9.1%, P=0.060), and the odds ratio (OR) was 0.53 (95% CI: 0.25-1.09). There was no difference in parents' genotype combination between the two groups, and in genotype distribution among different types of CHD. Analysis of genetic transmission indicated that mutation allele (+) existed transmission disequilibrium in CHD nuclear families. The percentage of allele (+) transmitted from parents was lower than that allele (-)with OR 0.26 (95% CI: 0.11-0.60). Conclusion MS gene variation in parents is associated with occurrence of CHD in offspring, and mutation allele (+) in parents may be related with the decrease of CHD risk in offspring.
Comparison Study on Clinical and Neuropathological Characteristics of Hamsters Inoculated With Scrapie Strain 263K in Different Challenging Pathways
2004, 17(1): 65-78.
Objective To understand the infectious characteristics of a hamster-adapted scrapie strain 263K with five different routes of infection including intracerebral (i.c.), intraperitoneal (i.p.),intragastrical (i.g.), intracardiac and intramuscular (i. m.) approaches. Methods Hamsters were infected with crude- or fine-prepared brain extracts. The neuropathological changes, PrPSc deposits,and patterns of PK-resistant PrP were analyzed by HE stain, immunohistochemistry (IHC) assay and Western blot. Reactive gliosis and neuron loss were evaluated by glial fibrillary acidic protein (GFAP)and neuron specific enolase (NSE) specific IHC. Results The animals inoculated in i.m. and i.p.ways with crude PrPSc extracts showed clinical signs at the average incubation of 69.2+-2.8 and 65.5±3.9 days. Inoculation in i.c. and intracardiac ways with fine PrPSc extracts (0.00035 g) caused similar,but relative long incubation of around 90 days. Only oneout of eight hamsters challenged ini.g way with low dosage (0.01 g) became ill after a much longer incubation (185 d), while all animals (4/4)with high dosage (0.04 g) developed clinical signs 105 days postinfection. The most remarkable spongiform degeneration and PrPsc deposits were found in brain stem among the five challenge groups generally. The number of GFAP-positive astrocytes increased distinctly in brain stems in all infection groups, while the number of NSE-positive cells decreased significantly in cerebrum, except i.c. group. The patterns of PK-resistant PrP in brains were basically identical among the five infection routes. Conclusion Typical TSE could be induced in hamsters by inoculating strain 263K in the five infection ways. The incubation periods in bioassays depend on infective dosage, administrating pathway and preparation of PrPSc. The neuropathological changes and PrPSc deposits seem to be related with regions and inoculating pathways.
Effects of AGEs on Oxidation Stress and Antioxidation Abilities in Cultured Astrocytes
2004, 17(1): 79-86.
Objective To investigate whether two kinds of in vitro prepared advanced glycation end products (AGEs), Glu-BSA and Gal-BSA, could change oxidation stress and anti-oxidation abilities in astrocytes, and thus might contribute to brain injury. Methods Changes of GSH, MDA, SOD,MAO-B, nitric oxide were measured after AGEs treatment. Results Both 0.1 g/L Glu-BSA and Gal-BSA could slightly decrease GSH level, while 1 g/L of them significantly decreased GSH level by 35% and 43% respectively. The MDA levels of both 1 g/L AGEs treated groups (306±13 and 346±22) were higher than that of the normal group (189±18), which could be inhibited by free radical scavenger NAC. The SOD activities of both 1 g/L AGEs treated groups (67.0±5.2 and 74.0±11.0)were lower than that of the normal group (85.2±8.0). Both 0.1 g/L AGEs could slightly increase the activity of MAO-B, while 1 g/L of them could increase MAO-B activity by 1.5 and 1.7 folds respectively. Both AGEs stimulation could produce NO level by 1.7 and 2 folds respectively.Conclusion Enhanced levels of astrocytic oxidation stress and decrease of antioxidation abilities may contribute to, at least partially, the detrimental effects of AGEs in neuronal disorders and aging brain.
Water Quality Assessment of the River Nile System:An Overview
2004, 17(1): 87-100.
Objectives The main objective of the present article is to assess and evaluate the characteristics of the Nile water system, and identify the major sources of pollution and its environmental and health consequences. The article is also aimed to highlight the importance of water management via re-use and recycle of treated effluents for industrial purpose and for cultivation of desert land. Method An intensive effort was made by the authors to collect, assess and compile the available data about the River Nile. Physico-chemical analyses were conducted to check the validity of the collected data. For the determination of micro-pollutants, Gas Chromatography (GC) and High Performance Liquid Chromatography (HPLC) were used. Heavy metals were also determined to investigate the level of industrial pollution in the river system. Results The available data revealed that the river receives a large quantity of industrial, agriculture and domestic wastewater. It is worth mentioning that the river is still able to recover in virtually all the locations, with very little exception. This is due to the high dilution ratio. The collected data confirmed the presence of high concentrations of chromium and manganese in all sediment samples. The residues of organo-chlorine insecticides were detected in virtually all locations. However, the levels of such residues are usually below the limit set by the WHO for use as drinking water. The most polluted lakes are Lake Maryut and Lake Manzala.Groundwater pollution is closely related to adjacent (polluted) surface waters. High concentrations of nutrients, E. coli, sulfur, heavy metals, etc. have been observed in the shallow groundwater, largely surpassing WHO standards for drinking water use. Conclusion A regular and continuous monitoring scheme shall be developed for the River Nile system. The environmental law shall be enforced to prohibit the discharge of wastewater (agricultural, domestic or industrial) to River Nile system.
Arsenic Induced Inhibition of δ-aminolevulinate Dehydratase Activity in Rat Blood and its Response To Meso 2,3-dimercaptosuccinic Acid and Monoisoamyl DMSA
2004, 17(1): 101-108.
Objective The objective of this study was to investigate arsenic induced changes in blood δ-aminolevulinic acid dehydratase (ALAD) after in vitro and in vivo exposure to this element and its response to co-administration of meso 2,3-dimercaptosuccinic acid (DMSA) and monoisoamyl DMSA (MiADMSA) either individually or in combination. Methods Rat whole blood was exposed to varying concentrations (0.1, 0.2 and 0.5 mmol/L) of arsenic (Ⅲ) or arsenic (V), to assess their effects on blood ALAD activity. Varying concentrations of MiADMSA and DMSA (0.1, 0.5 and 1.0 mmol/L) were also tried in combination to determine its ability to mask the effect of arsenic induced (0.5 mmol/L) inhibition of blood ALAD in vitro. In vitro and in vivo experiments were also conducted to determine the effects of DMSA and MiADMSA either individually or in combination with arsenic, on blood ALAD activity and blood arsenic concentration. Results In vitro experiments showed significant inhibition of the enzyme activity when 0.1-0.5 mmol/L of arsenic (Ⅲ and V) was used. Treatment with MiADMSA increased ALAD activity when blood was incubated at the concentration of 0.1 mmol/L arsenic (Ⅲ) and 0.1 mmol/L MiADMSA. No effect of 0.1 mmol/L MiADMSA on ALAD activity was noticed when the arsenic concentration was increased to 0.2 and 0.5 mmol/L. Similarly, MiADMSA at a lower concentration (0.1 mmol/L) was partially effective in the turnover of ALAD activity against 0.5 mmol/L arsenic (Ⅲ), but at two higher concentrations (0.5and 1.0 mmol/L) a complete restoration of ALAD activity was observed. DMSA at all the three concentrations (0.1, 0.5 and 1.0 mmol/L) was effective in restoring ALAD activity to the normal value.Conclusions The results thus suggest that arsenic has a distinct effect on ALAD activity. Another important toxicological finding of the present study, based on in vivo experiments further suggests that combined administration of DMSA and MiADMSA could be more beneficial for reducing blood ALAD inhibition and blood arsenic concentration than the individual treatment.
A Study on Detecting and Identifying Enteric Pathogens With PCR
Jun-Wen Li, XIU-QUAN SHI, FU-HUAN CHAO, Xin-Wei Wang, Jin-Lai Zheng, NONG Song
2004, 17(1): 109-120.
Objective To develop a rapid and definite diagnostic test of bacterial enteritis caused by pathogenic enterobacteria, the most frequent etiologic agent of infectious enteritis in the world.Methods A set of conventional PCR assays were applied to detect and identify salmonella, shigella,and E. coli O157:H7 directly from pure culture and fecal samples. The general primers of pathogenic enterobacteria were located on the uidA gene, which were found not only in E. coli nuclear acid, but also in Shigella and salmonella genes. Shigella primer was from ipaH gene whose coded invasive plasmid relative antigen existed both in plasmid and in genome. The primers of salmonella were designed from the 16SrRNA sequence. The primer of E. coli O157:H7 was taken from eaeA gene.Five random primers were selected for RAPD. The detection system included common PCR,semi-nested PCR and RAPD. Results This method was more sensitive, specific and efficient and its processing was rapid and simple. For example, the method could be used to specifically detect and identify salmonella, shigella, and E. coli O157:H7, and its sensitivity ranged from 3 to 50 CFU, and its detection time was 4 hours. Conclusion This PCR method, therefore, can serve as a rourine and practical protocol for detecting and identifying pathogenic microorganisms from clinical samples.