Search PubMed⌕ Search

Biomedical subjects

X Xia

Publications and source records attributed to X Xia.

138 records · Page 8Linked to original sources
PubMed1991

[An epidemiologic survey on a type E hepatitis (HE) outbreak].

This article deals with a HE outbreak, which occurred in Sulagong Village, Pan-jin Township, Yining County, Xinjiang. There was a total of 214 patients involved in the village, with an attack rate of 6.15 percent. Among the patients young people formed the majority. The attack rate between 20 to 24 years of age reached 17.9 percent. Attack rate of pregnant women between 18 to 35 years of age was significantly higher than that of the non-pregnant ones. The condition in pregnant patients was rather severe. Their case fatality rate was 5.88 percent and abortion rate was 17.64 percent. By epidemiological investigation, it was shown that the chief contributing cause of the HE outbreak was probably contaminated drinking water, and direct or indirect contact with the patients in the infectious stage was also a risk factor.

Adolescent↗
PubMed1991

[Preparation of compound membrane of traditional Chinese medicine for mouth ulcer].

The compound membrane of traditional Chinese medicine for mouth ulcer, which is made of drug-containing membrane and covering membrane, is a new type of preparation of traditional Chinese medicine. The comparison of different prescriptions and membrane materials in the preparation, adhesion and drug release of the membrane has shown that that PVA17-88-CMCNa (1:1) and PVA17-88 act best as the base of drug-containing membrane and covering membrane material respectively.

Administration, Topical↗
PubMed1990

IL-4 blocks the up-regulation of IL-2 receptors induced by IL-2 in normal human B cells.

A negative influence of IL-4 on the IL-2-induced B cell proliferation and differentiation has recently been reported. In this study, we have further investigated a role of IL-4 on human tonsillar B cell proliferation and IL-2R expression. IL-4 enhanced Staphylococcus aureus Cowan 1 strain (SAC)-induced B cell proliferation, reaching the peak on day 3. However, from day 4, IL-4 inhibited IL-2-induced proliferation. In the cross-linking study, IL-4 enhanced the density of 125I-IL-2-binding protein at low affinity binding condition (2 nM of 125I-IL-2) in SAC-activated B cells. However, IL-4 blocked the enhancement in the density of 125I-IL-2-binding proteins induced by IL-2, from day 3, in both high (50 pM of 125I-IL-2) and low affinity binding conditions, suggesting that IL-4 is able to block IL-2-induced IL-2R up-regulation. This was confirmed by a binding study: B cells that cultured for 3 days with SAC plus IL-2 expressed an average of 180 +/- 20 high affinity receptors/cell with a Kd of 12 pM and 5800 +/- 500 low affinity receptors/cell with a Kd of 980 pM. By coculturing with IL-4, high affinity receptors were almost undetectable and the expression of low affinity receptors was reduced by more than 80%. IL-4-mediated inhibition of IL-2-induced IL-2R expression does not seem to be due to the direct interaction between IL-4 and cell surface receptors, inasmuch as preincubation of cells with IL-4 for 60 min at 37 degrees C did not alter the binding of 125I-IL-2 to cells previously cultured for 3 days with SAC plus IL-2. These data suggest that IL-4 has a capacity to block the up-regulation of the high as well as low affinity IL-2R-induced by IL-2 in normal human B cells, and could provide a possible explanation for the decreased responsiveness of B cells to IL-2 in the presence of IL-4.

B-Lymphocytes↗
PubMed1989

Recombinant interleukin (IL) 2-induced human B cell differentiation is mediated by autocrine IL6.

The molecular mechanism of the interleukin (IL) 2-induced differentiation of human B cells has been investigated. The experimental results show that Staphylococcus aureus Cowan strain I (SAC) activation alone induces IL6 secretion from B cells. When B cells were activated by SAC, there was an increased transcription of the IL6 mRNA. It reached the peak level by 6 h and rapidly decreased to an undetectable level within 24 h. The IL6 concentration in the culture supernatants reached the peak at 24-48 h and decreased slightly in the following culture periods. Since IL 2 alone could induce IgG secretion, whether exogenous IL6 was added or not, and IL2 did not increase autocrine IL6 synthesis, it appears that IL2 induces the IL6 responsiveness of SAC-activated B cells to differentiate in the later stage of the culture. The addition of polyclonal anti-IL6 antibody inhibited IgG secretion. The antibody still efficiently blocked IgG secretion up to day 5, indicating an important role of autocrine IL6 in the IL2-driven B cell differentiation. However, the saturation dose of anti-IL6 antibody inhibited 50%-70% of IgG secretion, suggesting that IL2-induced B cell differentiation appears to be mediated by other factors besides IL6.

B-Lymphocytes↗
PubMed1988

Functional roles of gamma interferon in proliferation and differentiation of human B cell subpopulations.

We have studied the function of interferon-gamma (IFN-gamma) on human B cell proliferation and differentiation. When B cell subpopulations were separated by Percoll gradient centrifugation and stimulated by Staphylococcus aureus Cowan I (SAC), these subpopulations responded differently to lymphokines. Small B cells (60/80% Percell) were stimulated to proliferate by IFN-gamma alone. Large B cells (50/60% Percoll) did not respond to IFN-gamma but proliferated in response to B cell growth factor (BCGF) free of interleukin-2 (IL-2) and IFN-gamma. Although IFN-gamma alone could not induce the differentiation of SAC-activated B cells and did not support the growth of large B cells, it enhanced the proliferation and differentiation of both subpopulations in the presence of BCGF and IL-2. Also, IFN-gamma induced the expression of IL-2 receptor on B cells. Pretreatment of B cells with IFN-gamma for 48 h had a minor effect on the proliferation but significantly enhanced the differentiation in the presence of BCGF and IL-2; therefore, IFN-gamma may act as a differentiation factor. However, in a late stage of culture, IFN-gamma inhibited B cell differentiation. Our experimental data suggest that IFN-gamma is a growth factor for distinct subpopulation of SAC-activated human B cells and enhances the proliferation and differentiation and the expression of IL-2 receptor on B cells.

B-Lymphocytes↗
PubMed1987

Distinct culture requirements for activation and proliferation of human peripheral blood B lymphocytes by Staphylococcus aureus Cowan strain and growth factors.

The concentration of fetal calf serum (FCS) and the culture period were the crucial culture conditions in measuring B cell growth factor (BCGF) and IL-2 activity in vitro. Higher concentrations of FCS (10-15%) significantly inhibited BCGF activity; whereas, lower concentrations of FCS (less than 2.5%) were not sufficient for the response to IL-2. Kinetic experiments showed that the culture period for BCGF should be shorter than that for IL-2, while BCGF in combination with IL-2 induced a synergistic proliferation of B cells in a longer culture period. Adding BCGF after 48 h of SAC stimulation reduced the reaction. Hence, the conventional method using preactivated B cells does not measure BCGF but mostly IL-2. Furthermore, minute amounts of BCGF activity can be more sensitively determined by co-culturing with fixed amounts of IL-2.

Animals↗
PubMedDate not supplied

DAMBE: software package for data analysis in molecular biology and evolution.

DAMBE (data analysis in molecular biology and evolution) is an integrated software package for converting, manipulating, statistically and graphically describing, and analyzing molecular sequence data with a user-friendly Windows 95/98/2000/NT interface. DAMBE is free and can be downloaded from http://web.hku.hk/~xxia/software/software.htm. The current version is 4.0.36.

Biological Evolution↗
PubMedDate not supplied

Fine mapping of the human biotinidase gene and haplotype analysis of five common mutations.

Biotinidase deficiency is an autosomal recessive defect in the recycling of biotin that can lead to a variety of neurologic and cutaneous symptoms. The disease can be prevented or effectively treated with exogenous biotin. The biotinidase locus (BTD) has been maped to 3p25 by in situ hybridization. The gene has been cloned, the coding region sequenced, the genomic organization determined, and a spectrum of mutations has been characterized in more than 90 individuals with profound or partial biotinidase deficiency. We have conducted haplotype analysis of 10 consanguineous and 39 nonconsanguineous probands from the United States and 8 consanguineous probands from Turkey to localize BTD with respect to polymorphic markers on 3p and to investigate the origins of five common mutations. The inbred probands were homozygous for overlapping regions of 3p ranging in size from 1.1 to 80 cM which were flanked most narrowly by D3S1259 and D3S1293. Radiation hybrids and haplotype analysis of markers within this region suggest that BTD is located within a 0.1-cM region flanked by D3S3510 and D3S1286. The radiation hybrid data suggest that the BTD gene is oriented 5' to 3' between the centromere and the 3p telomere. Association studies indicate that the gene is closer to a third locus D3S3613 than D3S3510, two markers which cannot be resolved by existing linkage data. The BTD locus and D3S3613 must therefore lie between D3S3510 and D3S1286. Comparison of haplotypes reveals evidence for possible founder effects for four of the five common mutations.

Adult↗
PubMedDate not supplied

Mitomycin C reduces haze formation in rabbits after excimer laser photorefractive keratectomy.

PURPOSE: To investigate the effects of mitomycin C on haze after photorefractive keratectomy (PRK). METHODS: Twenty of 24 rabbits underwent bilateral 193-nm excimer laser PRK to correct -10.00 D of myopia; the remaining four rabbits were not operated (no PRK group). The right eyes of the 20 rabbits were treated with 0.02% mitomycin C during surgery (PRK+MMC group) and the left eyes did not receive 0.02% mitomycin C (PRK alone group). Clinical and histopathologic examinations were performed. RESULTS: The most severe haze in the PRK alone group after PRK reached grade 3; the PRK+MMC group did not exceed grade 1 haze. Statistically significant differences were found between the PRK+MMC and PRK alone groups from week 2 to week 26 after treatment (P<.01). Epithelial thickening appeared for 26 weeks in both PRK groups; no statistically significant differences were found between the two PRK groups (P>.05). A marked reduction of keratocytes in the anterior stroma of the PRK+MMC group was observed. At week 1, 2, and 4 after PRK, keratocytes of the PRK+MMC group were only 3.1+/-2.6, 6.8+/-4.7, and 12.4+/-5.7 keratocytes x 10(4)/microm2, respectively, while those of the PRK alone group were 41.2+/-80, 42.3+/-7.8, and 40.0+/-3.3 keratocytes x 10(4)/microm2, respectively. There were statistically significant differences between the two groups (P<.001). CONCLUSION: A single intraoperative application of topical mitomycin C during PRK in rabbits reduced corneal haze by inhibiting the proliferation of keratocytes.

Administration, Topical↗