[Research progress of micro-electro-mechanical systems micro gas chromatography columns].

The gas chromatography (GC) column is a key component of the gas chromatographic system, which is mainly used for the separation of mixed gas components. Compared with the traditional GC column, the micro GC column based on micro-electro-mechanical systems (MEMS) technology has the advantages of lighter weight, smaller volume, lower power consumption, and faster analysis. Furthermore, it can be integrated into a portable instrument, such as a miniaturized GC. The research progress of micro GC columns based on MEMS technology is summarized in this paper. First, the theoretical basis of the MEMS micro GC column is stated. Then, the layout and inner structure of the MEMS micro GC column, the stationary-phase support, and the preparation of the stationary phase are summarized. Finally, trends in the development of MEMS micro GC columns are discussed.

[High-aspect-ratio gas chromatography column based on micro-electro-mechanical system technology].

Miniaturization of gas chromatography (GC) columns is one of the key problems associated with microminiaturization of a chromatograph. In this study, a GC column with high-aspect-ratio microchannel based on micro-electro-mechanical system (MEMS) technology has been designed and manufactured. Simulation and analysis by the COMSOL software revealed that the GC column has even velocity field distribution, which is crucial for improving the separation efficiency of the column. The results show that heavy hydrocarbons (C6-C10) and compounds of benzene series can be successfully separated. The number of theoretical plate is 14028 plates/m, and the resolution of C7-C8 is 10.82. Due to its advantages of smaller volume, lower energy consumption, and better separation performance, the GC column can be applied in micro gas chromatography.

[Human metapneumovirus infection in children with acute respiratory tract inflammation in Urumuqi].

OBJECTIVE: To understand whether human metapneumovirus (hMPV) is one of the pathogens leading to the children's respiratory infections in Urumqi. METHODS: A total number of 209 samples were collected in the People's General Hospital of Xinjiang Uygur Autonomous Region from November 2006 to April 2007 with some from the hospitalized children, while the others from outpatient clinic. Specimens included nasopharyngeal aspirates (NPA) and swabs were analyzed. Samples were all tested hMPV M gene by RT-PCR while the two positive PCR amplicons were sequenced and compared with other hMPV in GenBank by Blast and DNAstar. RESULTS: Of all the 209 samples, two positive ones were tested. The identities between them were 83.8%. Results from Phylogenetic analysis showed that they might belong to two different clusters. CONCLUSION: hMPV was one of the pathogens leading to the children's respiratory tract infections in Urumqi, with two different hMPV groups existed in the same season.

Genetic characterization of measles viruses in China, 2004.

Genetic characterization of wild-type measles virus was studied using nucleotide sequencing of the C-terminal region of the N protein gene and phylogenetic analysis on 59 isolates from 16 provinces of China in 2004. The results showed that all of the isolates belonged to genotype H1. 51 isolates were belonged to cluster 1 and 8 isolates were cluster 2 and Viruses from both clusters were distributed throughout China without distinct geographic pattern. The nucleotide sequence and predicted amino acid homologies of the 59 H1 strains were 96.5%-100% and 95.7%-100%, respectively. The report showed that the transmission pattern of genotype H1 viruses in China in 2004 was consistent with ongoing endemic transmission of multiple lineages of a single, endemic genotype. Multiple transmission pathways leaded to multiple lineages within endemic genotype.

Emerging G9 rotavirus strains in the northwest of China.

Although G9 rotaviruses have become one of the important rotavirus genotypes worldwide, they have been uncommon in China. Recently, we reported G9 rotaviruses as a highly prevalent genotype in Xinjiang, the northwest part of China [Yang, X., Matthijnssens, J., Sun, H., Muhamaiti, J., Zhang, B., Nahar, S., Van Ranst, M., Rahman, M., 2008. Temporal changes of rotavirus strain distribution in a northwest city of China, 1996-2005. Int. J. Infect. Dis., June (Epub ahead of print)]. Here we report the genetic variations of the Xinjiang-G9 rotaviruses isolated between 1999 and 2005. Sequence analysis of the VP7 genes of Xinjiang-G9 strains indicated that they were more closely related to the contemporary global G9 strains than to the prototype Chinese G9 strains. However, their VP4 genes were most similar to those from the locally circulating G1P[8], G2P[4], G3P[6] and G3P[8] strains. This indicates that reassortment rather than antigenic drift might be the preferred evolutionary mechanism for the emergence of the G9 rotaviruses in Xinjiang. These findings will be of major significance for understanding the emergence of newly introduced rotavirus strains.

Temporal changes of rotavirus strain distribution in a city in the northwest of China, 1996-2005.

BACKGROUND: Very little is known about human rotaviruses in the northwest of China. To investigate the genomic diversity, we evaluated the distribution of rotavirus genotypes in this region covering a 10-year period (1996-2005). METHODS: Rotavirus antigen was detected in stool specimens by enzyme immunoassay (EIA), and G and P genotyping was performed by reverse transcription-polymerase chain reaction and nucleotide sequencing methods. RESULTS: A total of 783 stool specimens collected from children with diarrhea, under 5 years of age, attending an urban hospital in Xinjiang were tested for rotavirus antigen, and 398 (50.8%) were positive. Overall, the most prevalent rotavirus genotype was G1P[8] (40.0%), followed by G3P[8] (17.5%), G2P[4] (8.3%), and G2P[6] (6.5%). G1 rotavirus was the most prevalent genotype until 2004. However, in 2005, G3 rotavirus (51.9%) became a dominating strain. Only one G9 strain was isolated in this region (isolated for the first time in 1999) and it became a more prevalent strain (21.2%) in 2005. CONCLUSIONS: The results of this study are of importance to the decision makers in the evaluation of rotavirus vaccines in China.

Molecular epidemiology of measles viruses in China, 1995-2003.

This report describes the genetic characterization of 297 wild-type measles viruses that were isolated in 24 provinces of China between 1995 and 2003. Phylogenetic analysis of the N gene sequences showed that all of the isolates belonged to genotype H1 except 3 isolates, which were genotype A. The nucleotide sequence and predicted amino acid homologies of the 294-genotype H1 strains were 94.7%-100% and 93.3%-100%, respectively. The genotype H1 isolates were divided into 2 clusters, which differed by approximately 2.9% at the nucleotide level. Viruses from both clusters were distributed throughout China with no apparent geographic restriction and multiple co-circulating lineages were present in many provinces. Even though other measles genotypes have been detected in countries that border China, this report shows that genotype H1 is widely distributed throughout the country and that China has a single, endemic genotype. This important baseline data will help to monitor the progress of measles control in China.

Evolutionary history and global spread of the emerging g12 human rotaviruses.

G12 rotaviruses were first detected in diarrheic children in the Philippines in 1987, but no further cases were reported until 1998. However, G12 rotaviruses have been detected all over the world in recent years. Here, we report the worldwide variations of G12 rotaviruses to investigate the evolutionary mechanisms by which they managed to spread globally in a short period of time. We sequenced the complete genomes (11 segments) of nine G12 rotaviruses isolated in Bangladesh, Belgium, Thailand, and the Philippines and compared them with the genomes of other rotavirus strains. Our genetic analyses revealed that after introduction of the VP7 gene of the rare G12 genotype into more common local strains through reassortment, a vast genetic diversity was generated and several new variants with distinct gene constellations emerged. These reassortment events most likely took place in Southeast Asian countries and spread to other parts of the world. The acquirement of gene segments from human-adapted rotaviruses might allow G12 to better propagate in humans and hence to develop into an important emerging human pathogen.

G8 rotavirus strains isolated in the Democratic Republic of Congo belong to the DS-1-like genogroup.

Several G8P[6] and G8P[8] rotavirus strains were isolated from hospitalized patients in the Democratic Republic of Congo in 2003. To investigate their overall genomic relatedness and to determine to which genogroup they belonged, the complete genomes of strains DRC88 (G8P[8]) and DRC86 (G8P[6]) were determined. Genomic comparison of these two African G8 strains revealed that 10 out of their 11 gene segments, except for VP4, were nearly identical (>98.9% identical at the nucleotide level), suggesting that this rare G8P[8] rotavirus strain originated recently from a reassortment between a common G8P[6] strain and a strain with a P[8] specificity. A very close evolutionary relationship between 9 out of the 11 gene segments of DRC88 and DRC86 and rotavirus strains belonging to the DS-1-like (G2P[4]) "genogroup" was found, and several possible reassortment events preceding the occurrence of G8P[8] and G8P[6] human rotaviruses were hypothesized. Since the genes of G2P[4] rotavirus strains are very well adapted to infect humans, the acquirement of a new VP7 (G8) gene, and especially the replacement of P[6] (believed to be of animal origin) by P[8] (most common in human rotaviruses), might make DRC88-like rotaviruses very well equipped to become a predominant human rotavirus strain and an important pathogen on the African continent and the rest of the world. These findings have important implications for rotavirus vaccine development and highlight that typing of new rotavirus strains by merely sequencing their VP7 and VP4 genes provides us with only the tip of the iceberg regarding rotavirus diversity.

[Study on clinical isolates of human cytomegalovirus found in Urumqi by restriction fragment length polymorphism of PCR products].

BACKGROUND: The study was designed to investigate the status of molecular epidemiology of HCMV in Urumqi through genetic comparison of clinical isolates. METHODS: DNA sequences of 2.0-2.6 kb were amplified by polymerase chain reaction from three relatively conservative gene regions (DNA polymerase, glycoproteins H, and major immediate-early antigen) of 28 clinical HCMV strains and then were analysed by restriction enzymes. RESULTS: The restriction patterns of the clinical isolates which did not have relation in epidemiology were greatly different, but the patterns of the clinical isolates related in epidemiology such as strains paired in mother and infant were quite similar. Of eight mother and infant pairs, from whom HCMV were isolated, four pairs showed identity of restriction profiles within each pair for all three amplified regions, four pairs showed differences between mother and infant. CONCLUSION: These results confirm the high degree of genetic variability among cytomegalovirus strains in Urumqi. Analysis of PCR-RFLP can indicate transmission of HCMV infection and facilitate its molecular epidemiologic studies.