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Biomedical subjects

X H Li

Publications and source records attributed to X H Li.

At least 19 recordsLinked to original sources
PubMed2006

Acellular extracellular matrix for inguinal hernia repair.

To investigate the clinical safety and effectiveness of acellular extracellular matrix (AEM) for inguinal hernia repair, 53 well-conducted and well-chosen sequential cases with inguinal hernia (56 inguinal hernias) were included in our multi-center study. All the inguinal hernias were repaired using conventional tension-free surgical procedures after being classified with Gilbert methods. No rejection was observed after operation. All the incisions healed well and no recurrence was found at the sixth month follow-up. At the seventh month after operation, one case of recurrence of right-side bilateral inguinal hernia (type IV) and another case of recurrence of left-side inguinal hernia (type V) were found. No other recurrence was observed at the 18th month follow-up. The AEM material has good histocompatibility and biomechanics characters and can be used for inguinal hernia repair. We observed no infection, chronic pain, funiculotesticular reaction, local nodular or feeling of discomfort after operation. But a further study of the usage of AEM in the repair of type IV and V inguinal hernias is still needed.

Adolescent↗
PubMed2006

[Significance of hepatitis B virus PreS1-Ag, PreS2-Ag, large protein, PreS2-Ab detection and the prediction of HBV DNA replication.].

BACKGROUND: To explore the significance of hepatitis B virus PreS1-Ag, PreS2-Ag, large protein (LP) detection and the prediction of viral replication. METHODS: PreS1-Ag, PreS2-Ag, LP and HBV markers were measured by enzyme linked immunosorbent assay (ELISA) in 201 cases of infected serum. Serum HBV DNA level was quantitatively detected by real-time polymerase chain reaction (PCR). RESULTS: There were significant differences in positive rate between the PreS1-Ag, PreS2-Ag, LP, and HBsAg; the positive rate of PreS2-Ag and LP were higher than that of the HBeAg. No significant differences were found in the positive rates between LP and the levels of HBV DNA and there was a positive correlation between quantitations of HBV DNA and HBV-LP. CONCLUSION: Serum PreS1-Ag, PreS2-Ag and LP were laboratory markers that can accurately reflect HBV DNA reproduction, and were helpful complementarity to traditional HBV M. There is a close correlation between the number of copies of HBV DNA and the levels of HBV-LP.

DNA Replication↗
PubMed2006

[Clinical evaluation of HIV-1/2 antibody rapid tests.].

BACKGROUND: To evaluate the sensitivity and specificity of HIV-1/2 antibody rapid tests prior to licensing. METHODS: Four hundred forty, 264 and 300 blood samples were collected from normal blood donors, drug addicted individuals and HIV infected patients, respectively. All the samples were tested with 17 kinds of HIV-1/2 antibody rapid tests prior to licensing. The sensitivity and specificity of each test were calculated. RESULTS: The sensitivity for all evaluated rapid tests was 100% for detecting 300 strong positive samples for HIV antibody; the specificity for all evaluated rapid tests was within the range of 97.7%-100% for detecting 440 samples from normal blood donors; the sensitivity and specificity of all tests were within the range of 70.3%-95.1% and 59.1%-100% respectively for detecting 264 samples from HIV high risk population. CONCLUSION: The sensitivity and specificity of different tests were different and the samples from HIV high risk population may be very useful for evaluation of the quality of HIV-1/2 antibody rapid tests.

Blood Donors↗
PubMed2005

Delimitation of the rice wide compatibility gene S5 ( n ) to a 40-kb DNA fragment.

Wide compatibility varieties (WCVs) are a special class of rice (Oryza sativa L.) germplasm that produces hybrids with normal pollen and spikelet fertility when crossed with both indica and japonica subspecies. The wide compatibility gene S5 ( n ) has been used extensively in inter-subspecific hybrid breeding programs. We previously mapped the S5 locus to a 2.2-cM genomic region between RM253 and R2349 on chromosome 6, using a population of 356 F(1) plants derived from the three-way cross 02428/Nanjing11//Balilla. In this study, a chromosome walking strategy was employed to construct a physical map covering this genomic region using these two closest markers as the starting points. A physical map consisting of six overlapping BAC clones was formed, spanning a genomic region of 540-kb in length. By analyzing recombination events from a population of 8,000 F(1) plants derived from a three-way cross based on near isogenic lines of the S5 locus, the S5 locus was localized to a DNA fragment of 40-kb in length, flanked by two shotgun subclones, 7B1 and 15D2. Sequence analysis of this fragment predicted five open reading frames, encoding xyloglucan fucosyltransferases, dnak-type molecular chaperone BiP, a putative eukaryotic aspartyl protease, and a hypothetical protein. This result will be very useful in molecular cloning of the S5 ( n ) allele and marker-assisted transferring of the wide compatibility gene in rice breeding programs.

Aspartic Acid Endopeptidases↗
PubMed2005

Localization of pms3, a gene for photoperiod-sensitive genic male sterility, to a 28.4-kb DNA fragment.

Photoperiod-sensitive genic male-sterile (PSGMS) rice, in which pollen fertility is regulated by day-length, originally arose as a natural mutant in the rice cultivar Nongken 58 (Oryza sativa ssp. japonica). Previous studies identified pms3 on chromosome 12 as the locus of the original PSGMS mutation. In this study we have assigned the pms3 locus to a 28.4-kb DNA fragment by genetic and physical mapping. A cross between Nongken 58S (PSGMS line) and DH80 was used to produce an F2 population of about 7000 plants, from which 892 highly sterile individuals were obtained for recombination analysis. By analyzing recombination events in the sterile individuals using a total of 157 RFLP probes from a BAC contig covering the pms3 region, the pms3 locus was localized to a sub-region of less than 1.7 cM. Further analysis of recombination events using 49 additional probes isolated from this sub-region identified markers flanking the pms3 region on each side; these markers are only 28.4-kb apart. Sequence analysis of this fragment predicted the presence of five ORFs, found high homology with two ESTs in public databases, and detected three SNPs between the mutant and the wild-type parents, which may be helpful for identifying a candidate gene for pms3.

Chromosome Mapping↗
PubMed2004

Genetic dissection of embryo sac fertility, pollen fertility, and their contributions to spikelet fertility of intersubspecific hybrids in rice.

The partial sterility of hybrids has been a major barrier for utilization of the strong heterosis expressed in hybrids between Oryza sativa ssp. indica and O. sativa ssp. japonica. Wide-compatibility varieties, comprising a special class of germplasm, are able to produce fertile hybrids when crossed to both indica and japonica varieties. However, all the work on wide compatibility and majority of studies on indica/japonica hybrid sterility reported so far were based only on spikelet fertility; thus, it is not known to what extent male and female gamete abortions influence hybrid sterility. In this study, we investigated pollen fertility, embryo sac fertility, and spikelet fertility in an F1 population of 202 true hybrid plants derived from a three-way cross ('02428'/'Nanjing 11'//'Balilla'). A partial regression analysis showed that the pollen and embryo sac fertility contributed almost equally to spikelet fertility. QTL analysis based on a linkage map of 191 polymorphic marker loci identified two QTLs for pollen fertility, one QTL for embryo sac fertility, and three QTLs for spikelet fertility. The S5 locus, previously identified as a locus for wide compatibility by spikelet fertility analysis, is a major locus for embryo sac fertility, and a QTL on chromosome 5 had a major effect on pollen fertility. These two loci coincided with the two major QTLs for spikelet fertility. The study also detected a QTL on chromosome 8, showing a large effect on spikelet fertility but no effect on either pollen or embryo sac fertility. Very little interaction among the QTLs was detected. The implications of the findings in rice breeding programs are discussed.

Chromosome Mapping↗
PubMed2003

The genetic basis of stay-green in rice analyzed in a population of doubled haploid lines derived from an indica by japonica cross.

Delayed leaf-senescence, or stay-green, has been regarded as a desired characteristic for the production of a number of crops including rice. In this study, we analyzed the genetic basis of stay-green using a population of 190 doubled haploid lines from the cross between an indica parent Zhenshan 97 and a stay-green japonica parent Wuyujing 2. The population was tested in replicated field trials in 2 consecutive years, and six traits were defined to evaluate the stay-green characteristics. A genetic linkage map with 179 SSR (simple sequence repeat) marker loci was constructed. The software QTLMapper, based on a mixed linear model approach, was applied to detect QTLs, epistatic effects and their environmental interactions for these traits. A total of 46 main-effect QTLs was detected for the six traits that can be localized to 25 chromosomal regions. The individual effects of all the QTLs were small. Fifty digenic interactions were resolved that involved 66 loci distributed on all 12 chromosomes. Environmental interactions were detected for 18 of the main-effect QTLs and 14 of the epistatic interactions. Collectively, the epistatic effects and QTL by year interactions accounted for large proportions of the phenotypic variations. The results also showed that most of the stay-green traits were negatively correlated with yield and its component traits. The implications of the results in crop improvement were discussed.

Chromosome Mapping↗
PubMed2003

A catalogue of molecular, physiological and symbiotic properties of soybean-nodulating rhizobial strains from different soybean cropping areas of China.

We have analysed 198 fast-growing soybean-nodulating rhizobial strains from four different regions of China for the following characteristics: generation time; number of plasmids; lipopolysaccharide (LPS), nodulation factors (LCOs) and PCR profiles; acidification of growth medium; capacity to grow at acid, neutral, and alkaline pH; growth on LC medium; growth at 28 and 37 degrees C; melanin production capacity; Congo red absorption and symbiotic characteristics. These unbiased analyses of a total subset of strains isolated from specific soybean-cropping areas (an approach which could be called "strainomics") can be used to answer various biological questions. We illustrate this by a comparison of the molecular characteristics of five strains with interesting symbiotic properties. From this comparison we conclude, for instance, that differences in the efficiency of nitrogen fixation or competitiveness for nodulation of these strains are not apparently related to differences in Nod factor structure.

Bacterial Proteins↗
PubMed2002

Electrochemical behavior of Au colloidal electrode through layer-by-layer self-assembly.

Electrodes formed by Au colloidal nanoparticles have been obtained by layer-by-layer self-assembly using 1,6-hexanedithiol as cross-linkers. Cyclic voltammograms show that the peak-to-peak separation decreases as the number of Au colloidal layers increases. After seven layers of Au colloidal particles have been deposited, the multilayer electrodes have the electrochemical properties of metallic Au and show ideal microelectrode behavior. An equivalent circuit for the electrochemical impedance spectroscopy was established to model the working electrode. It is evident that by increasing the layer number of Au colloidals, the interfacial electron transfer is promoted, implying the electron-transfer process changes from a kinetically limited process to a diffusionally limited process.

Colloids↗
PubMed2002

Properties and biocompatibility of chitosan films modified by blending with PEG.

Chitosan (beta-1,4-D-glucosamine), a polysaccharide with excellent biological properties, has been widely used in biomedical fields, but many barriers still exist to its broader usage due to its chemical and physical limitations. Further work is needed to improve these properties, but changes of the chemical and physical properties will influence its biocompatibility, so the biological attribute of modified chitosan must be evaluated. In this study, the biocompatibility of chitosan modified by several methods was carefully evaluated at the cellular and protein levels using different physical and biological methods. The results provide a theoretical basis for screening biomaterials. We studied the properties of five kinds of materials made by blending chitosan with different types of polyethylene glycol (PEG). The properties included physical and chemical properties, such as mechanical strength, static contact angle, spectroscopy, thermodynamic attributes and so on. The mechanical properties were slightly improved with the proper amount of PEG, but the improvement was not obvious and was destroyed by the wrong proportion of PEG. Cultures of the cells and amounts and structures of the adsorbed proteins on different materials showed that the PEG effectively improved the biocompatibility of the materials. The PEG enhanced the protein adsorption, cell adhesion, growth and proliferation, but the effects were impaired by excessive PEG. The experiments also demonstrated that the optimum PEG concentration helped to maintain the natural structure of the protein adsorbed on the materials and that maintaining the natural structure benefited cell growth. Analysis of the results based on the intramolecular and intermolecular interaction forces leads to a basic theory for the modification of biomaterials.

3T3 Cells↗
PubMed2001

Effect of pH and soybean cultivars on the quantitative analyses of soybean rhizobia populations.

Quantitative analyses of fast- and slow-growing soybean rhizobia populations in soils of four different provinces of China (Hubei, Shan Dong, Henan, and Xinjiang) have been carried out using the most probable number technique (MPN). All soils contained fast- (FSR) and slow-growing (SSR) soybean rhizobia. Asiatic and American soybean cultivars grown at acid, neutral and alkaline pH were used as trapping hosts for FSR and SSR strains. The estimated total indigenous soybean-rhizobia populations of the Xinjiang and Shan Dong soil samples greatly varied with the different soybean cultivars used. The soybean cultivar and the pH at which plants were grown also showed clear effects on the FSR/SSR rations isolated from nodules. Results of competition experiments between FSR and SSR strains supported the importance of the soybean cultivar and the pH on the outcome of competition for nodulation between FSR and SSR strains. In general, nodule occupancy by FSRs significantly increased at alkaline pH. Bacterial isolates from soybean cultivar Jing Dou 19 inoculated with Xinjiang soil nodulate cultivars Heinong 33 and Williams very poorly. Plasmid and lipopolysaccharide (LPS) profiles and PCR-RAPD analyses showed that cultivar Jing Dou 19 had trapped a diversity of FSR strains. Most of the isolates from soybean cultivar Heinong 33 inoculated with Xinjiang soil were able to nodulate Heinong 33 and Williams showed very similar, or identical, plasmid, LPS and PCR-RAPD profiles. All the strains isolated from Xinjiang province, regardless of the soybean cultivar used for trapping, showed similar nodulation factor (LCO) profiles as judged by thin layer chromatographic analyses. These results indicate that the existence of soybean rhizobia sub-populations showing marked cultivar specificity, can affect the estimation of total soybean rhizobia populations indigenous to the soil, and can also affect the diversity of soybean rhizobial strains isolated from soybean nodules.

China↗
PubMed2001

[Study on diagnosis of small intestinal hemorrhage].

UNLABELLED: To explore the etiology and different methods of diagnosis for 33 cases of small intestinal hemorrhage, which were confirmed by surgery and/or pathology. METHODS: 33 cases of small intestinal hemorrhage were diagnosed by endoscopy, barium studies, radionucleotide scanning, angiograpy, exploratory laparotomy and intraoperative colonscopy, which were confirmed by surgery and/or pathology. RESULTS: Small intestinal tumors were found in 13 cases (39.39%), Leiomyoma in 8; infectious diseases in 8(24.24%); Meckel's diverticulum in 7(21.21%); and vascular malformation in 3(9.1%) and others in 2(6.06%). Among them, black stool (42.42%) is the most commonly seen. The common clinical presentation was middle-anemia and patients with unexplained abdominal pain (36.36%). Radionucleotide scanning was positive in 5 out of 7 cases, and all of five were Meckel's diverticulum. Endoscopy revealed 5 out of 20 cases. Exploratory laparotomy was performed in 6, 3 were found to have some lesions, and the other 3 were diagnosed by intraoperative colonscopy. CONCLUSIONS: Tumor is the nost common cause of small intestinal hemorrhage, mied anemia and black stool are the common clinical presentations, Radionucleotide scanning is one of the most useful diagnostic methods for Meckel's diverticulum and intraoperative colonscopy could elevate veracity of diagnosis.

Adolescent↗
PubMed2001

Identification of an 85-kb DNA fragment containing pms1, a locus for photoperiod-sensitive genic male sterility in rice.

Photoperiod-sensitive genic male-sterile rice has a number of desirable characteristics for hybrid rice production. Previous studies identified pms1, located on chromosome 7, as a major locus for photoperiod-sensitive genic male sterility. The objective of this study was to localize the pms1 locus to a specific DNA fragment by genetic and physical mapping. Using 240 highly sterile individuals and a random sample of 599 individuals from an F2 population of over 5000 individuals from a cross between Minghui 63 and 32001S, we localized the pms1 locus by molecular marker analysis to a genetic interval of about 4 cM, 0.25 cM from RG477 on one side and 3.8 cM from R1807 on the other side. A contig map composed of seven BAC clones spanning approximate 500 kb in length was constructed for the pms1 region by screening a BAC library of Minghui 63 DNA using RFLP markers and chromosomal walking. Analysis of recombination events in the pms1 region among the highly sterile individuals reduced the length of the contig map to three BAC clones. Sequencing of one BAC clone, 2109, identified two SSR markers located 85 kb apart in the clone that flanked the pms1 locus on both sides, as indicated by the distribution of recombination events. We thus concluded that the pms1 locus was located on the fragment bounded by the two SSR markers.

Chromosome Mapping↗