Kinetics of hydrothermal inactivation of endotoxins.

A kinetic model was established for the inactivation of endotoxins in water at temperatures ranging from 210°C to 270°C and a pressure of 6.2 × 10(6) Pa. Data were generated using a bench scale continuous-flow reactor system to process feed water spiked with endotoxin standard (Escherichia coli O113:H10). Product water samples were collected and quantified by the Limulus amebocyte lysate assay. At 250°C, 5-log endotoxin inactivation was achieved in about 1 s of exposure, followed by a lower inactivation rate. This non-log-linear pattern is similar to reported trends in microbial survival curves. Predictions and parameters of several non-log-linear models are presented. In the fast-reaction zone (3- to 5-log reduction), the Arrhenius rate constant fits well at temperatures ranging from 120°C to 250°C on the basis of data from this work and the literature. Both biphasic and modified Weibull models are comparable to account for both the high and low rates of inactivation in terms of prediction accuracy and the number of parameters used. A unified representation of thermal resistance curves for a 3-log reduction and a 3 D value associated with endotoxin inactivation and microbial survival, respectively, is presented.

[DC-SIGNR polymorphisms and its association with HIV-1 infection].

OBJECTIVE: To explore the association of the polymorphism of homologue of dendritic cell-specific intercellular adhesion molecule-3 (ICAM-3) grabbing nonintegrin (DC-SIGN related, DC-SIGNR) gene with the susceptibility to HIV-1 infection. METHODS: The distribution of the DC-SIGNR variants in the tandem repeat region and their association with HIV-1 infection in a cohort composed of 345 HIV-1 seropositive and 468 high-risk HIV-1 seronegative individuals was examined. RESULTS: There are 14 genotypes and 5 alleles in the DC-SIGNR repeat regions in the cohort. Although the most common DC-SIGNR allele among Chinese Han population and the Caucasian population is 7, it was found in a higher frequency in the Chinese than in Caucasians (67.1% vs.46.0%, P<0.01). HIV-1 seropositive individuals had a lower frequency of the genotype 7/7 than the high-risk seronegative individuals (38.55% vs. 48.29%, P=0.0057), but a higher frequency of genotype 9/5 (4.35% vs. 1.07%, P=0.0029). CONCLUSION: These results suggest that the tandem-repeat polymorphisms of the DC-SIGNR gene in the Chinese Han population exhibit unique genetic characteristics previously unrecognized in the Caucasian population. Genotype 9/5 seems to be a risk factor for HIV-1 infection in the Chinese population.

Reverse osmosis processing of organic model compounds and fermentation broths.

Post-treatment of an anaerobic fermentation broth was evaluated using a 150 gal/day, single cartridge prototype reverse osmosis (RO) system. Baseline tests were conducted at 25 degrees C using six organic model compounds representing key species found in the fermentation broth: ethanol, butanol, acetic acid, oxalic acid, lactic acid, and butyric acid. Correlations of the rejection and recovery efficiencies for these organic species, individually and in simulated mixtures, were obtained as a function of feed pressure with and without recirculation of the retentate. The actual fermentation broth obtained from a continuous-flow biohydrogen process was treated by the RO system under the operating conditions similar to those used in the baseline tests, resulting in greater than 95% removal of total organic carbon. These results are encouraging and useful for further studies on the feasibility of incorporating the RO technology into an integrated and field deployable wastewater management and water recovery system.

[Analysis of DC-SIGN and DC-SIGNR genetic polymorphism in Chinese Han population].

OBJECTIVE: To understand the genetic polymorphism of DC-SIGN's and DC-SIGNR's neck regions in normal Chinese Han population, and to obtain the genetic data of the two loci in Chinese Han population. METHODS: The genotypes and alleles of repeat sequences of DC-SIGN and DC-SIGNR neck region were typed by PCR, agarose gel electrophoresis and sequencing. Polymorphism information content (PIC) of DC-SIGNR was calculated. RESULTS: DC-SIGN genetic polymorphism was rare. Allele 7 was most and its frequency was 0.9808. 4-, 5-, 6- and 8- alleles were also found, although their frequencies were very low. Caucasians had only 6- and 8- allele mutants; DC-SIGNR genetic polymorphism was high, its PIC was 0.5312, 4-,5-,6-,7-,8-,9- alleles and 16 genotypes were found in normal Chinese Han population. The differences of 6/5,7/4,7/5,7/6,7/7,9/5,9/7,9/9 genotypes distribution and 5-,6-,7-,9- alleles frequency between normal Chinese Han population and Caucasian population were all extremely distinct (P<0.01). The inserted mutation seemed more in Chinese Hans than Caucasian population. CONCLUSION: DC-SIGN and DC-SIGNR genotypes and alleles distribution in Chinese Han population are significantly different from Caucasian population and with Chinese own population genetic characteristics, compared with Caucasians.

[Molecular cloning and expression of the severe acute respiratory syndrome-associated coronavirus nucleocapsid protein and its clinical application].

OBJECTIVE: To clone and express nucleocapsid (N) protein of the severe acute respiratory syndrome (SARS)-associated coronavirus, and to evaluate its antigenicity and application value in the development of serological diagnostic test for SARS. METHODS: SARS-associated coronavirus N protein gene was amplified from its genomic RNA by reverse transcript nested polymerase chain reaction (RT-nested-PCR) and cloned into pBAD/Thio-TOPO prokaryotic expression vector. The recombinant N fusion protein was expressed and purified, and its antigenicity and specificity was analyzed by Western Blot, to establish the recombinant N protein-based ELISA for detection of IgG antibodies to SARS-associated coronavirus, and SARS-associated coronavirus lysates-based ELISA was compared parallelly. RESULTS: The recombinant expression vector produced high level of the N fusion protein after induction, and that protein was purified successfully by affinity chromatography and displayed higher antigenicity and specificity as compared with whole virus lysates. CONCLUSION: The recombinant SARS-associated coronavirus N protein possessed better antigenicity and specificity and could be employed to establish a new, sensitive, and specific ELISA for SARS diagnosis.

[High-flux detection of HBV lamivudine resistant strains by genechip and analysis of mutant hotspots in those strains].

OBJECTIVE: Lamivudine resistant HBV strains in Shenzhen were detected at multiple sites and in large amounts to understand further the distribution of lamivudine resistant mutants. METHODS: 552 Hepatitis B patients's sera were examined using genechip method. Among them, 192 samples of lamivudine resistant mutant were further analyzed. RESULTS: In those 192 lamivudine resistant samples, 191 were YMDD mutants, 124 mutants of codon 528 and 9 mutants of codon 555. 88% YMDD mutants were multi-mutants of YVDD and codon 528; single mutants of YIDD; multi-mutants of YIDD and codon 528. 91% codon of YMDD mutants were GTG, ATT; the other 9% were ATA, ATC. CONCLUSIONS: These results suggest that mutants of codon 552 (YMDD) are core mutants. Mutants of codon 528 and 555 are incidental mutants, YVDD mutants always emerge with mutants of codon 528, but YIDD mutants appear differently. 9% YMDD mutants's codons are ATA or ATC. This may be the reason for the low positive rate shown by using the conventional PCR methods.

[Construction of a genechip method for detection of hepatitis B virus DNA, basal core promotor and Pre-C mutants].

BACKGROUND: To establish a genechip method for detection of hepatitis B virus (HBV) DNA, basal core promotor (BCP), and Pre-C mutants. METHODS: This study used two kinds of technology (PCR, oligochip), which can detect five mutant hotspots including nt 1 896, nt 1 899, nt 1 862, nt 1 764 and nt 1 762. The results of genechip method was verified by DNA sequencing. RESULTS: In detecting HBV DNA, the results of genechip were 100% consistent with those of DNA sequencing. In detecting HBV BCP and Pre-C mutants, 146 codons showed the same results using both methods, except for only 4 codons (P greater than 0.05). CONCLUSION: This convenient high throughput genechip method could detect several BCP and Pre-C mutant codons at the same time. These results suggest that genechip method has the same positive rate and specificity with DNA sequencing method. It has more advantages than the latter in detecting mixed mutants and therefore may be used in clinical practice.

[Early indexes to predict the therapeutic effect of interferon on chronic hepatitis B].

OBJECTIVE: To summarize the clinical changing characters of the clinical markers after interferon treatment in chronic hepatitis B (CHB) and make out practical indexes to predict the effect. METHODS: 150 CHB patients were randomly divided into two groups: therapeutic group (90) and control group (60) in the prospective controlled trial. The levels of endogenous interferon before treatment, interferon antibody at the end of the second month and fourth month after treatment, alanine aminotransferase (ALT) and HBV DNA in the serum were detected. Then the data was analysed to find out indexes for predicting the effect. RESULTS: (1) The clearance rate of HBeAg had no significant difference in age except for 20 - 30 and 30 - 40 (t > 2.331 2, P < 0.01). (2) It was more effective if ALT level was higher than 400 U/L before treatment and it decreased more than 50% two months after treatment. (3) The patients whose HBV DNA was negative (dot hybridization) or less than 10(6) copies/ml before treatment had higher rate of HBeAg clearance. (4) There was no effect on patients whose interferon antibody turned positive at the end of the second month. (5)A predictive method of comprehensive factors was made out, whose sensitivity, specificity, and accuracy were 80%, 100% and 90%, respectively. CONCLUSION: The clinical characters of these Chinese patients are different from those of the westerners and the effects of interferon have close relation to the levels of ALT, HBV DNA and interferon antibody.