Biomedical subjects

Zheng Feng

Publications and source records attributed to Zheng Feng.

30 records · Page 2Linked to original sources

PubMed2004

DNA sequences of Paragonimus skrjabini populations from five provinces in China.

BACKGROUND: To study differences among Paragonimus skrjabini (P. skrjabini) populations from five provinces in China (Guangdong, Fujian, Yunnan, Hubei, and Sichuan) and Paragonimus szechuanensis. METHODS: DNA sequences were obtained from the ITS2 and CO1 genes and phylogenetic trees were constructed from the results. Sequences were also obtained from several other species of Paragonimus for comparative purposes. RESULTS: Although differences existed in the DNA sequence among P. skrjabini populations from five provinces, the differences were very small. There was also some resemblance between P. miyazakii from Japan and Fujian strains of P. skrjabini. CONCLUSION: All studied populations can be regarded as different strains of P. skrjabini; P. szechuanensis is not a separate species but may be a geographical strain of P. skrjabini. We also found that P. miyazakii may be synonymous with P. skrjabini.

Animals↗

PubMed2004

[Gene cloning, expression and serological evaluation of diagnostic antigen Em18 for alveolar echinococcosis].

OBJECTIVE: To clone, express and serologically evaluate the Em18 antigen gene of Echinococcus multilocularis for diagnostic purpose. METHODS: Polymerase chain reaction (PCR) was employed for amplification of the target gene fragments which was then ligated with pET28a+ vector. The constructed plasmid was transferred into E. coli BL21 (DE3) for expression. The recombinant proteins were purified with Ni-NTA agarose by affinity chromatography. 237 sera were used for evaluating diagnostic value of the recombinant Em18 antigen. RESULTS: Two high-level expression clones (designated as ReEm18-1 and ReEm18-2) were obtained. ReEm18-1 showed the expected sequence, ReEm18-2 showed the same sequence but with 27 nucleotides deletion. The molecular weight of the two expression proteins was Mr 28,000 and 26,000, respectively. Serological evaluation by ELISA was carried out using sera from 101 patients with alveolar echinococcosis (AE), 47 with cystic echinococcosis (CE), 30 with cysticercosis (CC), 10 with hepatic cancer (HC), 9 with schistosomiasis (Sj) and 40 from healthy persons (NH) from both endemic and non-endemic areas. The results showed an overall sensitivity of 86.1% and 90.1% with ReEm18-1 and ReEm18-2 for AE sera, specificity 93.4% and 94.1%, positive predictive value 90.6% and 91.9%, negative predictive value 90.1% and 92.8% and efficiency 90.3% and 92.4%, respectively. The correlation analysis between the size of AE lesions and the serum absorbance reacted with recombinant Em18 antigens showed that there was a positive correlation between antibody level and the course of the disease. CONCLUSION: ReEm18 antigens are specific for AE diagnosis, and the serum antibody level displays a good correlation with the course of the disease at early stage. Similar results achieved by both ReEm18-1 and ReEm18-2 antigens.

Animals↗

PubMed2004

[Analysis of cytochrome c oxidase I and cytochrome b genes of F1 in laboratory line Oncomelania hupensis hupensis].

OBJECTIVE: To analyze the diversity of F1 in laboratory line Oncomelania hupensis hupensis. METHODS: Genomic DNA was isolated, and cytochrome c oxidase I (COI) and cytochrome b (Cytb) genes were amplified by polymerase chain reaction (PCR). The nucleotide sequences of the PCR products were analyzed by GENETYX-MAC software package (ver. 9). RESULTS: Pairwise divergences among six F1 individuals were found in 12.2% nucleotides in COI gene fragments. 13.5% of genetic divergences between O. h. hupensis and O. h. robertsoni were identified. 94 amino acids were observed in difference. In Cytb gene fragments, 6.4% of divergence was observed among four F1 samples. 25 amino acids were observed differently. The divergence of Cytb genes from O. h. robertsoni and O. h. hupensis were 13.6%, included 6 amino acids. CONCLUSION: Diversities were found in both COI and Cytb gene sequences of F1 in laboratory line O. h. hupensis.

Amino Acid Sequence↗

PubMed2003

Evolutionary and biomedical implications of a Schistosoma japonicum complementary DNA resource.

Schistosoma japonicum causes schistosomiasis in humans and livestock in the Asia-Pacific region. Knowledge of the genome of this parasite should improve understanding of schistosome-host interactions, biomedical aspects of schistosomiasis and invertebrate evolution. We assigned 43,707 expressed sequence tags (ESTs) derived from adult S. japonicum and their eggs to 13,131 gene clusters. Of these, 35% shared no similarity with known genes and 75% had not been reported previously in schistosomes. Notably, S. japonicum encoded mammalian-like receptors for insulin, progesterone, cytokines and neuropeptides, suggesting that host hormones, or endogenous parasite homologs, could orchestrate schistosome development and maturation and that schistosomes modulate anti-parasite immune responses through inhibitors, molecular mimicry and other evasion strategies.

Amino Acid Sequence↗

PubMed2003

[Taxonomic status in DNA sequences of five species of genus Paragonimus].

OBJECTIVE: To analyze the taxonomic status of Paragonimus hokuoensis, P. paishuihoensis, P. menglaensis, P. bangkokensis and P. xiangshanensis in Genus Paragonimus Braun, 1899. METHODS: DNA sequences were obtained from the ITS2 and CO I genes and phylogenetic trees were built from these. RESULTS: There are some DNA sequence differences among P. paishuihoensis, P. menglaensis, P. bangkokensis and P. xiangshanensis, but the differences are small. P. hokuoensis and P. skrjabini are similar in DNA sequence. CONCLUSION: P. paishuihoensis, P. menglaensis, P. bangkokensis and P. xiangshanensis are closer in the genetic relationship. Their taxonomic status lies between P. skrjabini and P. westermani. The genetic relationship between P. hokuoensis and P. skrjabini is very close.

Animals↗

PubMed2003

[Study on DNA sequences of Paragonimus skrjabini populations from five provinces in China].

OBJECTIVE: To study differences among Paragonimus skrjabini populations from five provinces (Guangdong, Fujian, Yunnan, Hubei, Sichuan) and Paragonimus szechuanensis and to analyze the taxonomic status of P. heterotremus and P. veocularis in the Genus Paragonimus Braun, 1899. METHODS: DNA sequences were obtained from the ITS2 and CO1 genes and phylogenetic trees were built. RESULTS: Difference of the DNA sequences among P. skrjabini populations from five provinces were minor. P. veocularis and P. skrjabini were similar in DNA sequences. There were also some resemblances between P. miyazakii from Japan and the Fujian isolates of P. skrjabin. In addition, P. heterotremus was found to be closer to P. skrjabini and quite a distance from P. westermani in the phylogenetic tree. CONCLUSION: All studied populations can be regarded as different strains of P. skrjabini; P. szechuanensis is not a separate species, but possibly a geographical strain of P. skrjabini. Also found was that P. veocularis and P. miyazakii may be the synonyms of P. skrjabini. As a separate species, P. heterotremus was found to be closer to P. skrjabini and quite a distance from P. westermani in the genetic relationship.

Animals↗

PubMed2002

Molecular cloning and characterization of Plasmodium falciparum transportin.

A cDNA encoding transportin, a protein involved in the nuclear import of M9 nuclear localization signal-bearing proteins, has been cloned from the malaria parasite Plasmodium falciparum. The complete cDNA consists of 3,667 bp encoding 1,136 amino acid residues. Amino acid sequence analysis revealed that Ran-GTP and M9 binding domains are highly conserved in P. falciparum, suggesting that the transportin-mediated nuclear transport pathway exists in this protozoan parasite. Southern blot analysis revealed that the transportin gene exists as a single copy in the malarial genome.

Active Transport, Cell Nucleus↗

PubMed2002

Mathematical modelling of schistosomiasis japonica: comparison of control strategies in the People's Republic of China.

We present the first mathematical model on the transmission dynamics of Schistosoma japonicum. The work extends Barbour's classic model of schistosome transmission. It allows for the mammalian host heterogeneity characteristic of the S. japonicum life cycle, and solves the problem of under-specification of Barbour's model by the use of Chinese data we are collecting on human-bovine transmission in the Poyang Lake area of Jiangxi Province in China. The model predicts that in the lake/marshland areas of the Yangtze River basin: (1) once-yearly mass chemotherapy of humans is little better than twice-yearly mass chemotherapy in reducing human prevalence. Depending on the heterogeneity of prevalence within the population, targeted treatment of high prevalence groups, with lower overall coverage, can be more effective than mass treatment with higher overall coverage. Treatment confers a short term benefit only, with prevalence rising to endemic levels once chemotherapy programs are stopped; (2) depending on the relative contributions of bovines and humans, bovine treatment can benefit humans almost as much as human treatment. Like human treatment, bovine treatment confers a short-term benefit. A combination of human and bovine treatment will dramatically reduce human prevalence and maintains the reduction for a longer period of time than treatment of a single host, although human prevalence rises once treatment ceases; (3) assuming 75% coverage of bovines, a bovine vaccine which acts on worm fecundity must have about 75% efficacy to reduce the reproduction rate below one and ensure mid-term reduction and long-term elimination of the parasite. Such a vaccination program should be accompanied by an initial period of human treatment to instigate a short-term reduction in prevalence, following which the reduction is enhanced by vaccine effects; (4) if the bovine vaccine is only 45% efficacious (the level of current prototype vaccines) it will lower the endemic prevalence, but will not result in elimination. If it is accompanied by an initial period of human treatment and by a 45% improvement in human sanitation or a 30% reduction in contaminated water contact by humans, elimination is then possible.

Animals↗

PubMed2002

Identification of Taenia asiatica in China: molecular, morphological, and epidemiological analysis of a Luzhai isolate.

Multiple analysis has characterized a recently described tapeworm of people, Taenia asiatica, in mainland China. Six adult tapeworms collected from people of the Zhuang minority residing in the southern part of China (Luzhai isolate) were comparatively analyzed with other tapeworms from people: T. asiatica (n = 2, South Korea), T. saginata (n = 1, Poland; n = 1, Korea), and T. solium (n = 1, People's Republic of China). Experimental infections with eggs from the Luzhai isolate in pigs and cattle produced cysticerci, each with a hookletless scolex and with wartlike formations on the external surface of the bladder wall. There were rostellar protrusions in the scolices of adult worms. Random amplified polymorphic DNA analysis using 3 arbitrary primers produced bands identical to those of the Korean T. asiatica. Conversely, T. saginata and T. solium exhibited different banding patterns. Phylogenetic relationships inferred from the complete nucleotide sequences of the internal transcribed spacer 2 placed the Chinese tapeworms consistently within the T. asiatica clade by 96% bootstrapping value in the maximum likelihood analysis, 96% in maximum parsimony, and 100% in neighbor joining. These collective data demonstrate that T. asiatica is sympatrically distributed with the other 2 species of Taenia in the human host in mainland China.

Adolescent↗

PubMed2002

[Study on genomic diversity among different isolates of Schistosoma japonicum in China].

OBJECTIVE: To study genomic diversity among the isolates of Schistosoma japonicum in China. METHODS: Schistosome adults were collected from different endemic areas. Mitochondrial NADH dehydrogenase 1 (ND1) and cytochrome C oxidase 1 (CO1) gene fragments of the worms were amplified by PCR, cloned into plasmid, and finally sequenced. Program MEGA was used for sequence analysis. RESULTS: The ND1 and CO1 genes amplified from different geographic strains were 476 bp and 1,033 bp, respectively. There are two distinct haplotypes, type I and II, for both ND1 and CO1 nucleotide sequences. The differences between the two types were 4.0% and 3.4%. They are considered to be two different genetypes by the phylogenetic analysis. In individual mitochondrial gene, type I of ND1 was fixedly accompanied with type I of CO1 gene, and type II of ND1 with type II of CO1. CONCLUSION: There are two different genetypes of ND1 and CO1 genes of S. japonicum in China.

Animals↗

PubMed2002

[Improvement in the preparation of Paragonimus westermani chromosome for karyotype analysis].

OBJECTIVE: To improve Paragonimus westermani chromosome preparation technique. METHODS: After being exposed to colchicine, the gonadal cells of P. westermani were treated by the following procedures: hypotonicity, fixation, dropping onto a slide and staining. RESULTS: The chromosome number of P. westermani is 22, and the karyotype is 2m + 6Sm + 14t chromosome. CONCLUSION: The improved technique of chromosome preparation is feasible to operate and the chromosome is clear enough for karyotype analysis.

Animals↗

PubMed2002

Application of remote sensing for surveillance of snail habitats in Poyang Lake, China.

OBJECTIVE: To identify snail habitats and monitor the changes by combining remote sensing technique with the ground-based ecological data. METHODS: Of 100 survey sites selected throughout Poyang Lake, 75 were randomly identified from 574 land mass units: 50 were from snail habitats and 25 were from non-snail habitats based on a historical survey (1982-1984); 25 sites with habitats that did not have snails were also selected. Each site, covering 10,000 m2, was divided into a grid of 100 cells from which 20 cells were randomly selected. Snails, when present, were collected from a 4 m2 frame placed in the center of the selected cell. Satellite Landsat TM images were obtained for the same period as the ground survey data collected. Unsupervised classification was used to classify the images. Identified land-cover types were correlated with snail habitat. RESULTS: The sensitivity and specificity of classified snail habitat were 90.0%-95.6% and 61.1%-68.6%, respectively. Based on the classification, estimated snail habitat areas in Poyang Lake increased from 623.4 km2 in 1999 to 762.8 km2 in 2000. CONCLUSION: Snail habitats are associated with grassland-covered areas. Classified images can be used to identify snail habitats, determine their areas, and monitor snail habitat changes caused by annual fluctuations of key environmental factors.

Animals↗