Transgenic expression of human cytoxic T-lymphocyte associated antigen4-immunoglobulin (hCTLA4Ig) by porcine skin for xenogeneic skin grafting.

Porcine skin is frequently used as a substitute of human skin to cover large wounds in clinic practice of wound care. In our previous work, we found that transgenic expression of human cytoxicT-lymphocyte associated antigen4-immunoglobulin (hCTLA4Ig) in murine skin graft remarkably prolonged its survival in xenogeneic wounds without extensive immunosuppression in recipients, suggesting that transgenic hCTLA4Ig expression in skin graft may be an effective and safe method to prolong xenogeneic skin graft survival. In this work, using a transgene construct containing hCTLA4Ig coding sequence under the drive of human Keratine 14 (k14) promoter, hCTLA4Ig transgenic pigs were generated by somatic nuclear transfer. The derived transgenic pigs were healthy and exhibited no signs of susceptibility to infection. The hCTLA4Ig transgene was stably transmitted through germline over generations, and thereby a transgenic pig colony was established. In the derived transgenic pigs, hCTLA4Ig expression in skin was shown to be genetically stable over generations, and detected in heart, kidney and corneal as well as in skin. Transgenic hCTLA4Ig protein in pigs exhibited expected biological activity as it suppressed human lymphocyte proliferation in human mixed lymphocyte culture to extents comparable to those of commercially purchased purified hCTLA4Ig protein. In skin grafting from pigs to rats, transgenic porcine skin grafts exhibited remarkably prolonged survival compared to the wild-type skin grafts derived from the same pig strain (13.33 ± 3.64 vs. 6.25 ± 2.49 days, P < 0.01), further indicating that the transgenic hCTLA4Ig protein was biologically active and capable of extending porcine skin graft survival in xenogeneic wounds. The transgenic pigs generated in this work can be used as a reproducible resource to provide porcine skin grafts with extended survival for wound coverage, and also as donors to investigate the impacts of hCTLA4Ig on xenotransplantation of other organs (heart, kidney and corneal) due to the ectopic transgenic hCTLA4Ig expression.

Prevalence and risk factors of belching disorders: A cross-sectional study among freshman college students.

OBJECTIVES: Belching disorders seriously affect quality of life; however, their prevalences and risk factors remain unknown. The aim of our study was to determine the prevalence and risk factors, particularly lifestyle factors, of belching disorders among freshman college students in central China. METHODS: A cross-sectional study was conducted in September 2019 in Huazhong University of Science and Technology (Wuhan, Hubei Province, China). The subjects were asked to complete a self-administered questionnaire for data collection, including sociodemographic information, lifestyle factors, and gastrointestinal symptoms. Belching disorder was diagnosed based on the Rome IV criteria. Univariate and multivariate logistic regression analyses were performed to determine the risk factors for belching disorders. RESULTS: A total of 3335 subjects were enrolled, and 78.26% were men. Among them, 1.95% (65/3335) reported belching disorders. Significant differences in the Pittsburgh Sleep Quality Index (PSQI), Student-Life Stress Inventory (SLSI) scores, and consumption of whole grains, black tea, coffee were found between the belching and non-belching groups. Multivariate logistic regression analysis showed that coffee consumption at least once weekly and a high total SLSI score (over mean + standard deviation) were independent risk factors for belching disorders, while intake of whole grains at least once weekly was a protective factor. CONCLUSIONS: Excessive belching is a common disorder among freshman college students in central China. Lifestyle factors, including consumption of whole grains and coffee, and stress, were associated with belching disorders. Therefore, dietary intervention may be a potential management for belching disorders.

High pressure-assisted vacuum-freeze drying: A novel, efficient way to accelerate moisture migration in shrimp processing.

High pressure processing (HPP), as nonthermal processing technology, has the potential to increase the drying rate due to its improvement of heat and mass exchange in different processes. In this study, the moisture migration in shrimps during HPP-vacuum-freeze drying (HPP-VFD) processes has been monitored by using low-field nuclear magnetic resonance and magnetic resonance image (MRI) in comparison with hot air-drying and VFD. Based on the T2 relaxation spectra, three water fractions corresponding to bound water (hydrogen-bonded water), immobile water (water trapped by organization structure or cell member), and free water were observed. For group B, with increasing drying time (4 to 22 hr), the transverse relaxation times of T21 , T22 , and T23 were significantly decreased (76.79%, 57.78%, and 40.9%) (P < 0.05). The content of immobile water (A22 ) and free water (A23 ) decreased (81.55% and 89.07%), whereas the bound water (A21 ) increased (7.26%). In comparison with group B, the T21 , T22 , and T23 of group C showed greater decrease (83.12%, 87.12%, and 89.57% for group C) so that HPP pretreatment could shorten the relaxation time. MRI analysis further proved that HPP-VFD drying has improved drying efficiency, and moisture migration was from the exterior to the interior part with increasing drying time. SEM analysis demonstrated that no significant damage of muscle fibers with narrower gaps was observed for groups B and C. Overall, HPP, as a pretreatment technology, could accelerate the moisture migration and improve the drying efficiency of VFD process for shrimp. PRACTICAL APPLICATION: High pressure processing (HPP) is now well known as a nonthermal processing technology and becoming increasingly acknowledged. However, there is limited information about its application in shrimp-drying process and the moisture dynamic of shrimp subjected to high pressure processing-assisted vacuum-freeze drying. This study could provide valuable information regarding the moisture status and migration in HPP-VFD shrimp monitored by LF-NMR and MRI methods. The results showed that HPP processing at 550 MPa for 10 min can be used as an interesting method for drying pretreatment, increasing its drying rate and consequently reducing its process time, and it demonstrated that the methods used in this study had good correlation coefficient with physicochemical properties of shrimp, which may be real-time and nondestructive monitoring methods for shrimp-drying process.

Comparison of Clinical Efficacy and Complications Between Laparoscopic Partial and Open Partial Hepatectomy for Liver Carcinoma: A Meta-Analysis.

OBJECTIVE: To contrast the clinical effects and complications for the treatment of liver carcinoma in laparoscopic partial hepatectomy (LPH) and open partial hepatectomy (OPH). METHODS: The multiple databases were adopted to search relevant studies, and the articles eventually satisfying the inclusion criteria were included. All the meta-analyses were conducted with the Review Manager 5.3, and to estimate the quality of each article risk of bias table was performed. RESULTS: In the end, 17 studies including 3897 patients were involved, which eventually satisfied the eligibility criteria. The number of samples in LPH group and OPH group were 1723 and 2174, respectively. The results of heterogeneity test suggested that recurrence rate (odds ratio [OR] = -20.11, 95% confidence interval, CI [-35.93 to -4.29], P = .01; P for heterogeneity <.00001, I2 = 100%), hospital days (mean difference (MD) = -2.21, 95% CI [-2.53 to -1.88], P < .000001; P for heterogeneity = .41, I2 = 58%), and blood loss (MD = -68.09, 95% CI [-85.07 to -51.11], P < .00001; P for heterogeneity = .13, I2 = 37%) were significantly different, whereas operating time (MD = 4.00, 95% CI [-17.50 to 25.49], P = .72; P for heterogeneity <.00001, I2 = 99%) and complication events (OR = 0.68, 95% CI [0.46 to 1.01], P = .05; P for heterogeneity = .34, I2 = 11%) between LPH and OPH were insignificantly different. CONCLUSION: This study demonstrated that clinical efficacy of OPH was better than that of LPH to some extent, but LPH was a quicker recovery and less harmful therapy.

Bama miniature pigs (Sus scrofa domestica) as a model for drug evaluation for humans: comparison of in vitro metabolism and in vivo pharmacokinetics of lovastatin.

The objective of this study was to demonstrate that Bama miniature pigs are a suitable experimental animal model for the evaluation of drugs for man. To this end, in vitro lovastatin metabolism at the minipig liver microsomal level and in vivo pharmacokinetics were studied. Results were compared with those obtained from humans. Our data indicate that the main metabolites and enzyme kinetic parameters of lovastatin metabolism are similar in pigs and humans. Triacetyloleandomycin, a specific inhibitor of human CYP3A4, inhibited the metabolism of lovastatin in pig and human liver microsomes. In addition, the pharmacokinetic parameters and absolute bioavailability suggested that the absorption and elimination of lovastatin in Bama miniature pigs were similar to those in humans. Lovastatin was distributed across many organs in pigs, but the highest levels were found in the stomach, intestines, and liver. Within 96 h, 7% and 82% of the given dose was excreted in the urine and feces, respectively. In addition, no significant species differences in the plasma protein binding ratio of lovastatin and the rates of lovastatin hydrolysis to beta-hydroxyacid lovastatin were apparent. From these results, we conclude that Bama miniature pigs are suitable for use in drug evaluation studies.

Biodegradation of tetrachlorothylene using methanol as co-metabolic substrate.

OBJECTIVE: To investigate the biodegradation of tetrachloroethylene (PCE) using methanol as electron donor by acclimated anaerobic sludge. METHODS: HP-6890 gas chromatograph (GC), together with HP-7694 autosampler, was used to analyze the concentration of PCE and intermediates. RESULTS: PCE could be decholrinated reductively to DCE via TCE, and probably further to VC and ethylene. The degradation of PCE and TCE conformed to first-order reaction kinetics. The reaction rate constants were 0.8991 d(-1) and 0.068 d(-1), respectively, and the corresponding half-life were 0.77 d and 10.19 d, respectively. TCE production rate constant was 0.1333 d(-1), showing that PCE was degraded more rapidly than TCE. CONCLUSION: Methanol is an electron donor suitable for PCE degradation and the cometabolic electron donors are not limiting factors for PCE degradation.

Impact of High Hydrostatic Pressure on the Shelling Efficacy, Physicochemical Properties, and Microstructure of Fresh Razor Clam (Sinonovacula constricta).

The effects of high hydrostatic pressure (HHP) treatments (200, 300, and 400 MPa for 1, 3, 5 and 10 min) on the shelling efficacy (the rate of shelling, the rate of integrity and yield of razor clam meat) and the physicochemical (drip loss, water-holding capacity, pH, conductivity, lipid oxidation, Ca2+ -ATPase activity, myofibrillar protein content), microbiological (total viable counts) and microstructural properties of fresh razor clam (Sinonovacula constricta) were investigated. HHP treatments significantly (P < 0.05) increased shelling efficiency, water-holding capacity, pH, conductivity, and lipid oxidation, and HHP-treated razor clam showed lower levels of microorganisms and drip loss than untreated razor clam. Levels of thiobarbituric acid reacting substances (TBA) in HHP-treated razor clam were greatly increased (up to 0.93 ± 0.09 mg MDA/kg at 400 MPa for 10 min) which was caused by the formation of hydroperoxides during HHP treatment. All HHP treatments were found to have adverse effects on the activity of Ca2+ -ATPase and the content of myofibrillar protein (MP), which might be due to the substantial damage to the tertiary structure of proteins at high pressure. Moreover, scanning electron microscopy (SEM) revealed the compaction of the muscle fibers and a decrease in the extracellular space with increasing pressure and holding time. This phenomenon was mainly correlated with the compaction of muscle fibers and denaturation, aggregation, and gelation of muscle protein triggered by high pressure. In general, HHP could be applied as a safe and effective nonthermal technology to produce high-quality shelled razor clam. PRACTICAL APPLICATION: High hydrostatic pressure (HHP) is now well known as a nonthermal processing technology and becoming increasingly acknowledged. However, it has not been widely applied to shell seafood due to its uncertain influence on its quality and shelling property. This study could provide valuable information regarding the shelling efficacy, physicochemical properties, and microstructure of razor clam treated by HHP. And it demonstrated that HHP showed a positive impact on quality of razor clam treated by HHP.

[Expression of CYP3A29 mRNA in Chinese experimental miniature pig's livers quantitated with real-time reverse transcription polymerase chain reaction].

CYP3A29 is the most important key enzyme for drug metabolism in pig's liver. Research of the characters of CYP3A29 mRNA expression in Chinese experimental miniature pig's livers is significant for evaluating it whether suitable for experimental model for drug metabolism mediated by human CYP3A4 enzyme. In this study, the levels of CYP3A29 mRNA expression in livers of Bama miniature pigs, Guizhou miniature pigs and Rongchang pigs were studied by TaqMan-mediated quantitative RT-PCR. Results indicated that the CYP3A29 mRNA expression levels in livers of these species were close to literatures of human. Levels of CYP3A29 mRNA expression were similar among livers of Bama miniature pigs, Guizhou miniature pigs and Rongchang pigs, but interindividual variations were quite large. It was suggested that Bama miniature pigs and Guizhou miniature pigs were both feasible for experimental animal model for evaluating drug metabolism in some degree.

Anaerobic degradation of tetrachloroethylene using different co-substrates as electron donors.

OBJECTIVE: To investigate the biodegradation of tetrachloroethylene (PCE) by acclimated anaerobic sludge using different co-substrates, i.e., glucose, acetate, and lactate as electron donors. METHODS: HP-6890 gas chromatograph (GC) in combination with auto-sampler was used to analyze the concentration of PCE and its intermediates. Results PCE could be degraded by reductive dechlorination and the degradation reaction conformed to the first-order kinetic equation. The rate constants are k(lactate) > k(glucose) > k(acetate). The PCE degradation rate was the highest in the presence of lactate as an electron donor. CONCLUSION: Lactate is the most suitable electron donor for PCE degradation and the electron donors supplied by co-metabolic substrates are not the limiting factors for PCE degradation.

Normal Electrocardiogram of Bama Miniature Pigs (Sus scrofa domestica).

This study determined the normal ECG patterns and values for Bama miniature pigs. Standard limb-lead ECG were recorded from 120 clinically healthy, unanesthetized piglets (age, 2 to 4 mo). The values for the ECG parameters (mean ± 1 SD) were: heart rate, 125.56 ± 18.80 bpm; P amplitude, 0.11 ± 0.03 mV; QRS amplitude, 0.63 ± 0.31 mV; P duration, 43.99 ± 5.98 ms; QRS complex, 55.27 ± 7.02 ms; RR interval, 487.55 ± 77.32 ms; PR interval, 90.72 ± 11.94 ms; QT interval, 244.72 ± 25.27 ms; and mean electrical axis, 22.2 ± 80.3°. The P waves were predominantly positive in leads I and II and in the augmented unipolar limb aVF lead; by comparison, the QRS patterns were less uniform. The T waves were slightly positive in leads II, III, and aVF. The determination and publication of the normal ECG patterns and values of Bama minipigs facilitates understanding of the electrocardiographic changes that arise under experimental conditions.

[Studies on the infectivity by porcine endogenous retrovirus with porcine skin fibroblast in vitro and in vivo].

To understand the infectivity by porcine endogenous retrovirus with porcine skin fibroblast cell in vitro and in vivo, porcine skin fibroblast cell established by our laboratory were co-cultured with neo/HEK293 cell for the infection of PERV in vitro, and were subcutaneously transplantated to SCID (severe combined immuno-deficiency) mice for the infection of PERV in vivo, laying the foundation for valuation of biologic safety of xenotransplantation. The event of neo/HEK293 cells infected by PERV occurred during co-culture of porcine skin fibroblast cells with neo/HEK293 cells, expanding the rang of the infection of porcine endogenous retrovirus. After pig cells transplantated subcutaneously in SCID mice, the microchimerism (78.57%) of pig cells occurred widely, and there was phenomena of integration of PERV provirus (85.71%) in several organs or tissues remote from the injected sites, indicating infection of PERV in SCID mice in vivo, yet, there is no evidence of active viral replication in analysis of PERV env RNA of these tissues or organs. The infectivity of porcine endogenous retrovirus with porcine skin fibroblast cells in vitro and in vivo were demonstrated in this study, and there is no evidence of active viral replication of PERV in vivo. It is an important event of biologic safety which attention must be paid to potential hazard of infectious interspecies transmission of PERV during xenotransplantation.

Lentiviral transgenic microRNA-based shRNA suppressed mouse cytochromosome P450 3A (CYP3A) expression in a dose-dependent and inheritable manner.

Cytochomosome P450 enzymes (CYP) are heme-containing monooxygenases responsible for oxidative metabolism of many exogenous and endogenous compounds including drugs. The species difference of CYP limits the extent to which data obtained from animals can be translated to humans in pharmacodynamics or pharmacokinetics studies. Transgenic expression of human CYP in animals lacking or with largely reduced endogenous CYP counterparts is recognized as an ideal strategy to correct CYP species difference. CYP3A is the most abundant CYP subfamily both in human and mammals. In this study, we designed a microRNA-based shRNA (miR-shRNA) simultaneously targeting four members of mouse CYP3A subfamily (CYP3A11, CYP3A16, CYP3A41 and CYP3A44), and transgenic mice expressing the designed miR-shRNA were generated by lentiviral transgenesis. Results showed that the CYP3A expression level in transgenic mice was markedly reduced compared to that in wild type or unrelated miR-shRNA transgenic mice, and was inversely correlated to the miR-shRNA expression level. The CYP3A expression levels in transgenic offspring of different generations were also remarkably lower compared to those of controls, and moreover the inhibition rate of CYP3A expression remained comparable over generations. The ratio of the targeted CYP3A transcriptional levels was comparable between knockdown and control mice of the same gender as detected by RT-PCR DGGE analysis. These data suggested that transgenic miR-shRNA suppressed CYP3A expression in a dose-dependent and inheritable manner, and transcriptional levels of the targeted CYP3As were suppressed to a similar extent. The observed knockdown efficacy was further confirmed by enzymatic activity analysis, and data showed that CYP3A activities in transgenic mice were markedly reduced compared to those in wild-type or unrelated miR-shRNA transgenic controls (1.11±0.71 vs 5.85±1.74, 5.9±2.4; P<0.01). This work laid down a foundation to further knock down the remaining murine CYP3As or CYPs of other subfamilies, and a basis to generate CYP knockdown animals of other species.

[Diversity and bacteria community structure of activated carbon used in advanced drinking water treatment].

Two granular activated carbon (GAC) samples with 1.5 a and 5 a age were collected, Bacterial genome DNA was extracted for the 16S rDNA gene amplification, and then a bacterial 16S rDNA gene clone library was constructed. After the phylogenetic analysis of 16S rDNA sequences, bacterial diversity and community structure of two activated carbon biofilm sample were studied. The results showed the bacteria in GAC with 5 a age could be divided into 11 groups, which were as follows alpha-Proteobacteria (26.5%), beta-Proteobacteria (16.3%), delta-Proteobacteria (16.3%), Planctomycetes (12.2%), Gemmatimonadetes (6.1%), Acidobacteria (4.1%), Nitrospira (2.0%), gamma-Proteobacteria (2.0%), Bacteroidetes (2.0%), Actinobacteria (2.0%), Unclassified Bacteria (10.2%). The bacteria in GAC with 1.5 a age could be divided into 10 groups, which were as follows alpha-Proteobacteria (21.6%), Planctomycetes( 10.8%), Bacteroidetes (10.8%), beta-Proteobacteria (9.0%), Acidobacteria (9.0%), Nitrospira (7.2%), detla-Proteobacteria (7.2%), Unclassified Proteobacteria (5.4%), Gemmatimonadetes (3.6%), Unclassified Bacteria (14.4%). The results revealed a variety of bacterial divisions on the studied GAC biofilm. Proteobacteria had the highest share in the two total clones, and alpha- and beta-Proteobacteria were on a dominant position. A relatively high proportion of delta-Proteobacteria was observed in the biofilm of GAC with 5 a age, and Nitrospira was in a minor proportion. However, a totally converse condition appeared in GAC with 1.5 a age. Two pathogenic bacteria, Afipia and Chryseobacterium, were detected in analyzed GACs, which implies a potential microbial risk in water supply.

[Experimental study of autotrophic denitrification bacteria through bioaugmentation of activated sludge from municipal wastewater plant].

Activated sludge of municipal wastewater treatment plant was domesticated by sulfur as the electron donor under autotrophic. The sludge activity was determined by measuring growth rate of sludge. The removal efficiency of nitrate and sulfate production efficiency were analyzed by continuously measuring the concentration of NO3(-)-N and SO4(2-). When the removal efficiency of nitrate was more than 90%, 16S rRNA genetic libraries were built up to compare their microbial biodiversity. The growth rate of sludge is 0.177 g/(L x d). The relation between concentration of nitrate and time meets first order reaction kinetics. The bacteria in the sludge affiliated with Beta-Proteobacteria, Deta-Proteobacteria, Gamma-Proteobacteria and Unclassified bacteria. Beta-Proteobacteria is the main phylum in the sludge. Bacteria related to Thiobacillus denitrificans from denitrifying bioreactor perform 48.65%. In addition, the bacteria of Denitratisoma sp., Curvibacter sp., Thermomonas sp., Geobacter sp. are existed in the sludge. The study of autotrophic denitrifying bacteria diversity is conducive to optimization of reaction conditions and efficient removal of nitrate.

Determination of propofol UDP-glucuronosyltransferase (UGT) activities in hepatic microsomes from different species by UFLC-ESI-MS.

Propofol O-glucuronidation has been used as probe reaction to phenotype UGT1A9 activity in human liver, thus a sensitive and specific method for determination of propofol O-glucuronide (PG) is urgently desirable. In the current study, a new LC-ESI-MS method for determination of PG in hepatic microsomes from human (HLM), monkey (CyLM), dog (DLM), minipig (PLM), rat (RLM) and mouse (MLM) was developed and validated using 4-methylumbelliferyl-ß-d-glucuronide as an internal standard (IS). PG and IS was separated by a Shim-pack XR-ODS column (100 mm × 2.0mm, 2.2 µm, Shimadzu) under gradient conditions with the mobile phase of acetonitrile and water containing 0.2% acetic acid (v/v). The mass spectrometric detection was performed under selected ion monitoring (SIM) for PG at m/z 353 and IS at m/z 351. The assay exhibited linearity over the range 0.05-30 µM for PG with the correlation coefficient of 0.9995. The intra- and inter-day precision was less than 7.2%, with accuracy in the range 93.8-107.5%. The developed method was successfully used for characterizing interspecies and human individual differences in the O-glucuronidation activity towards propofol, as well as investigating inhibitory effects of androsterone and phenylbutazone on propofol O-glucuronidation in HLM.

Light microscopic, electron microscopic, and immunohistochemical comparison of Bama minipig (Sus scrofa domestica) and human skin.

Here we sought to evaluate the possibility of using Chinese Bama miniature pig skin as a suitable animal model for human skin. Morphologic features of the skin of Bama miniature pigs resemble those of human skin, including skin layer thickness, development of a superficial vascular system, structure of the dermal-epidermal interface, and extracellular matrix. The characteristics and densities of Langerhans cells, fibroblasts, vascular endothelial cells, and mast cells were similar between Bama pig and human skin. Immunohistochemistry showed that miniature pigs and humans have the same antigenic determinants of human laminin, fibronectin, filaggrin, collagen I, collagen III, collagen IV, and keratin but not CD34, ICAM1, or S100. In addition, collagen type I from Bama miniature pig skin exhibited physicochemical characteristics resembling those of human skin, in regard to HPLC chromatography, UV spectroscopy, amino-acid composition, and SDS-PAGE analysis. Given these results, we concluded that Bama miniature pigs have great potential as a human skin model and for developing dermal substitute materials in wound repair. However, we also observed some disparities between the skin of Bama miniature pigs and humans, including pigment cell distribution, sweat gland types, and others. Therefore, further studies are needed to completely evaluate the effects of these interspecies differences on the actual application of the model.

[Oxidation of trichloroethylene in water with permanganate].

In order to investigate the removal ability of chlorinated hydrocarbons, the most widely existent pollutant trichloroethylene(TCE) was chosen as the aim pollutant, and the self-made permanganate solution was chosen as oxidant. When the oxidant concentration was 0.276 g x L(-1), the removal rate of TCE reached 100% at 30 degrees C within 30 min. The removal of TCE with permanganate followed the pseudo-first order kinetics with the reaction rate constant K(obs) was 0.1429 min(-1) and the half-life t1/2 was 4.85 min. The reaction rate constant of TCE was increased with increase of KMnO4 concentration and temperature, and almost not affected by pH and ionic strength.

[Microsatellite analysis in Wistar and Spague-Darley outbred rats].

Genetic quality of outbred stock has an important effect for the experimental results by using those animals, but methods and standardization of genetic detection for outbred stock are absent. In the present study, 6 microsatellite markers were screened for Wistar from Beijing and Spague-Darley (SD) from Shanghai outbred rats by fluorescence-based semi-automated genotyping method. Good polymorphisms were detected on all the 6 microsatellite loci, with 36 alleles found in the 2 stocks, 5-8 alleles each locus, and the polymorphic information content (PIC) ranged from 0.5892 (D11Mgh3) to 0.8019 (D6Mit1), with an average of 0.6881. 25 and 26 alleles were detected in the 6 loci, and averages of unbiased expected heterozygosity were 0.6260 and 0.6249 in Wistar and SD outbred rats, respectively. No significant differences of genetic diversity index were tested between populations. The Fst per locus was varied from 0.0461 to 0.4363, and the average Fst of all loci was 0.2069, which implied large genetic differentiation between populations. Nei's (1972) genetic distance and Nei's (1978) unbiased genetic distance measures between the 2 stocks were 1.2862 and 1.2726, respectively, which indicated the distant genetic relationship and low genetic identity between them. All loci in Wistar and 4 of 6 loci in SD outbred rats showed significant deviations from Hardy-Weinberg equilibrium (HWE), and all deviations were caused by deficiency of heterozygous individuals. From the results, there is abundant genetic variation in Wistar and SD outbred rats. Large genetic differentiation existed between these two outbred stocks, and each possessed distinct genetic characteristic. Deviation from HWE seems a frequent problem in the 2 outbred stocks. This genetic research on outbred rats should assist in developing genetic monitoring methods and standardization of the outbred rats.

[Sulfide removal from wastewater by nanoscale iron].

Influencing factors, adsorption isotherm, adsorption kinetics and preliminary discussion on the mechanism of sulfide adsorption by nanoscale iron prepared in laboratory were studied using manual simulation sulfide wastewater. Experimental results indicate that the removal efficiency of S2- increases with increasing iron dosage and decreases with increasing initial S2- concentration and pH values. The removal efficiency of S2- is 100% when initial concentration is less than 100 mg x L(-1) and are 87.34%, 65.80% and 44.61% at pH 2, 7 and 13. The temperature at 25 degrees C favors the maximum adsorption of S2- with 19.17 mg x g(-1) of equilibrium adsorption quantity and the adsorption capacity decreas at higher or lower temperature. The adsorption data fit well to the Langmuir equation and the Freundlich equation. The sulfide adsorption follows the pseudo second order equation with the maximum initial sorption rate(h) is 1.575 3 mg x (g x mg)(-1) at 25 degrees C and the adsorption rate constant increases with the increasing of temperature. The activation energy(Ea) is 8.22 kJ x mol(-1). The mechanism of sulfide removal is being sorbed onto the iron nanoparticles via formation of surface compleses, FeOSH and iron sulfides (FeS, FeS2, FeSn).

[Dechlorination mechanisms of chlorinated hydrocarbons by supported nanoscale Pd/Fe].

Some volatile chlorinated hydrocarbons such as VC, 1,1-DCE, TCE, PCE, gamma-HCH, were dechlorinated by synthesized supported nanoscale Pd/Fe. The dechlorination reactions of PCE, TCE, 1,1-DCE, VC, gamma-HCH follow the pseudo-frist order kinetics equations with the k(obs) of 2.79 h(-1), 2.35 h(-1), 1.12 h(-1), 2.14 h(-1) and 4.02 h(-1) respectively. Little or no medial products were detected and the main end products were C2H6 and C2H4 during the dechlorination of VC, 1,1-DCE, TCE, PCE. The total carbon ratio of C2H6 and C2H4 were 70% and 10% respectively during the dechlorination of TCE. The supported nanoscale Pd/Fe particles after exposed to air for 24 h were used for 8 cycle experiments and the results indicate that the particles have favorable stability. The reactivity has no obvious decrease after 200 hours' successive dechlorination experiments of gamma-HCH which indicates that the particles represent good durability. The reaction activation energy of all the chlorinated hydrocarbons are bigger than 29 kJ x mol(-1) which shows that the surface-chemical reaction rather than diffusion is the rate-limiting step in the metal-mediated dechlorination process. A consistence between the experimental data and simulated curves indicates that the muti-step reaction pathways proposed offer a better explanation of the reaction mechanisms than sequential hydrogenolysis reactions in the transformation of chlorinated hydrocarbons by supported nanoscale Pd/Fe.