Biomedical subjects

X Tang

Publications and source records attributed to X Tang.

At least 91 records · Page 5Linked to original sources

PubMed2000

Detailed allelic loss mapping on 7q32 in nasopharyngeal carcinoma.

OBJECTIVE: The present research group had found high frequency of loss of heterozygosity(LOH) of D7S500-D7S495 on chromosome band 7q32 in nasopharyngeal carcinoma, this study was conducted to further find the deletion region. METHODS: Higher density of loci on 7q32 in 30 tumors was studied by using microsatellite analysis. RESULTS: The frequency of LOH was 63.3%. The highest frequency of LOH was identified at the loci of D7S500-D7S509-D7S495, among which a common deletion of D7S509 was found. CONCLUSION: A putative tumor suppressor gene may be present around D7S509.

Chromosomes, Human, Pair 7↗

PubMed2000

An analysis of two polymorphic points of the 7th intron of human p53 gene.

OBJECTIVE: To detect polymorphic points of the 7th intron of human p53 oncogene. METHODS: Polymerase chain reaction (PCR) and double- strand DNA direct sequencing were used to analyse sequence alteration of p53 intron 7. One hundred and five cases of normal human peripheral blood samples with no genetic relation were investigated. RESULTS: There were two polymorphic points in the 7th intron of p53 gene. The first one was localized at 73 base pair (bp) to 3'-end of exon 7; the other one at 93. Three genotypes were found. Twenty-two cases were of type TG, 37 cases were of type CT, and the other 46 cases were of heterozygote. Because the first point was alteration of GGGCCC to GGGTCC or its heterozygote, it had a point alteration of enzyme Apa I. CONCLUSION: There are two polymorphic points in the 7th intron of human p53 gene, which may be of importance to identification of individual genetic relation and to judging of a case in forensic medicine.

Genes, p53↗

PubMed2000

Measurement and significance of oblique occipital frontal diameter and superior inferior diameter of hepatic left lobulus in patients with hepatic fibrosis.

OBJECTIVE: To study the changes and significance of oblique occipital frontal diameter (OFD) and superior inferior diameter (SID) of the hepatic left lobulus in different stages of hepatic fibrosis, and to evaluate the value of corresponding serological examination in the non-invasive diagnosis to hepatic fibrosis and cirrhosis. METHODS: Seventy-two patients with chronic hepatitis were confirmed by biopsy. OFD and SID of the hepatic left lobulus were measured by type B ultrasonic flaw detector. Serum levels of hyaluronic acid (HA), laminin (LN), type IV collagen (CIV) and type III procollagen (PCIII) were measured by radioimmunoassay. RESULTS: SID of the hepatic left lobulus in S(4) stage was 5.7cmA1.5cm, significantly shorter than the values of 7.7cmA1.4 cm in S(0) stage. OFD of the hepatic left lobulus was longer in S(4) stage than S(0) stage, but the difference didn't reach statistical significance. Serum levels of HA, LN,CIV, and PCIII elevated as the increase of fibrosis. HA and PCIII increased to 273.4mug/LA131.3mug/L and 167. 4mug/LA48.1mug/L in S3 stage from 66.2mug/LA35.0mug/L and 103. 4mug/LA23.8mug/L in S(0) stage. CONCLUSION: Changes in of SID and OFD of the hepatic left lobulus and serum levels of HA and PCIII may indicate indirectly mid-late hepatic fibrosis or early cirrhosis.

Adult↗

PubMed2000

[Molecular cloning of a novel gene located on chromosome 3p25.3 and an analysis of its expression in nasopharyngeal carcinoma].

OBJECTIVE: To obtain the novel genes associated with human nasopharyngeal carcinoma(NPC) on chromosome 3p24-26. METHODS: Twenty epithelial-derived expressed sequence tags(EST) were selected from chromosome 3p24-26 where loss of heterozygosity(LOH) frequently occurs in NPC tissues. Primers were designed based on the sequences of these ESTs. RT-PCR was used to amply their corresponding cDNA fragments from NPC cell line HNE1 and primary cultures of normal nasopharyngeal epithelial cells. The differential expression of two ESTs, T93093 and R41598, was confirmed by Northern blot. Then, expression of EST T93093 was further detected in 7 normal nasopharyngeal and 19 NPC biopsies. cDNA library screening was used to get its full cDNA sequence and the sequence of this novel gene was analyzed by bioinformatics. RESULTS: Thirteen ESTs(T62511, N39155, N68660, R61275, T95314, R06143, H52697, H66521, AA128685, AA284537, N52379, AA054180, and H98090) showed the similar expression level and 5 ESTs(R00732, R07573, R98052, H91759, H17566) showed no expression in both types of cells. EST T93093 was down-expressed, whereas EST R41598 up-expressed in NPC HNE1 cells. The EST T93093 was also found to be down-expressed in 26.3%(5/19) of NPC biopsies. The full length cDNA of this gene was obtained and named NAG-7, which is located at chromosome 3p25.3. Its 1677 bp full length cDNA has a potential open reading frame(ORF) predicting a 94 amino acid protein with a molecular weight of 11023.87 Dalton. Bioinformatics analysis of the NAG-7 gene shows that it is a transmembrane protein containing a protein kinase C(PKC) phosphorylation site and a myristyl site. It has no significant homology to any reported genes in database of GenBank(AF086709). CONCLUSION: NAG-7 is a novel gene down-expressed in NPC, which may be involved in the development of NPC.

Chromosome Mapping↗

PubMed2000

[Relationship between interleukin-2, interleukin-2 receptor and the non-and hypo-responsiveness to hepatitis B vaccine].

OBJECTIVE: To study the relationship between interleukin-2 (IL-2), soluble interleukin-2 receptor (sIL-2R) and the non-and-hypo-responsiveness to hepatitis B vaccine. METHODS: Peripheral blood mononuclear cells (PBMC) isolated from 21 non-and -hypo-responders, 22 hyperresponders and 21 chronic HBsAg carriers were incubated in the presence of HBsAg and phytohaemagglutinin (PHA). The levels of IL-2 and sIL-2R in the supernatants of activated cells were measured by an enzyme-linked immunosorbent assay. RESULTS: The average level of IL-2 in the non-and-hypo-responders was significantly lower than that in the hyperresponders (t=8.80, P<0.001), but was comparable to that in chronic HBsAg carriers (q=0.06, P>0.5). Between the hyperresponders and the non-and-hypo-responders, the average sIL-2R levels showed no noticeable difference. CONCLUSION: The results suggest that low level of IL-2 may be one of the causes and mechanisms of non-and-hypo-responsiveness to hepatitis B vaccine.

Carrier State↗

PubMed2000

[The adsorption on attapulgite and cross-linked agar beads entrapped attapulgite(CAA)].

The adsorption of four drugs with certain toxicity, i.e. chlorpromazine, quinidine, diazepam and phenobarbital on attapulgite and Cross-linked Agar Beads Entrapped Attapulgite(CAA) was determined in this study. The results revealed that attapulgite possessed high adsorption for the cation drugs(chlorpromazine and quinidine), moderate adsorption for diazepam, and slight adsorption for phenobabital. The adsorption in attapulgite was quite quick and came to equilibrium in about 30 min. No significant difference(P > 0.05) of adsorption on attapulgite was observed at 30 min and 60 min. The adsorbent selectivity on CAA was the same as that on attapulgite. The speed of the adsorption was slower on CAA than on attapulgite, but the quantity adsorpted on CAA and that on attapulgite had no marked difference(P > 0.05) after 60 min. CAA preserved the adsorption property of attapulgite fundamentally. CAA overcame the dispersibility of attapulgite distinctly and showed good hemocompatibility and a fair blood flow rate in hemoperfusion. It may play an important role in the separation of blood components and in hemopurification.

Adsorption↗

PubMed2000

P16 overexpression in pituitary adenomas studied by immunohistochemistry and in situ hybridization.

OBJECTIVES: To examine the expression of p16 gene and the clinicopathological characteristics of 31 pituitary adenomas. To investigate the relationship between p16 expression and cell proliferative activity by analyzing the expression of proliferating cell nuclear antigens (PCNA). METHODS: Immunohistochemistry and in situ hybridization were performed on freshly-prepared paraffin-embedded specimens of 31 pituitary adenomas. RESULTS: Varying degrees of overexpression of the p16 gene was found in the tumors specimens. A higher proportion of p16 positive tumor cells was associated with bigger size, more frequent invasion and higher recurrence of the tumors. The expression of p16 was found to be significantly associated with the degree of PCNA expression. CONCLUSION: Though inactivation of the p16 gene is known in wide range of tumors, our study suggested that p16 overexpression might play a role in the development and progression of pituitary adenomas.

Adenoma↗

PubMed2000

Comparison of Botox with a Chinese type A botulinum toxin.

OBJECTIVE: To confirm and compare the therapeutic efficacies and remote effects of a Chinese type A botulinum toxin (CBTX-A, Lanzhou Biological Products Institute, China) and Botox (Allergan Inc., USA) for focal dystonia and muscle spasm. METHODS: Prospective open study was conducted over 4 years for focal dystonia and muscle spasm. We enrolled 785 patients: 192 were injected with Botox and 593 with CBTX-A. They were followed for 3 to 48 months. Meanwhile single fiber electromyography (SFEMG) was performed in a subset of 40 patients before, 2-3 weeks, 5-8 weeks and 4-5 months after injection of Botox or CBTX-A. RESULTS: There were no significant differences in clinical effects from two preparations, including the latency of response, maximal benefit and duration of improvement. The dose of the Chinese preparation which produced effects similar to Botox was higher. A significant increase in jitter was demonstrated 2-3 weeks after injection in both groups and fiber density values increased at the same time or later and remained 4-5 months after injections. CONCLUSION: Both preparation are safe and effective treatments for patients with focal dystonia and muscle spasm. They both have subclinical effects on neuromuscular transmission of remote uninjected muscles. The Chinese preparation is a little less powerful but much cheaper than Botox.

Adolescent↗

PubMed2000

[Effect of IGF1 receptor gene antisense oligodeoxynucleotide on T24 urinary bladder cancer cells].

OBJECTIVE: To evaluate the effects of autocrine blockage on T24 urinary bladder cancer cells. METHODS: Semiquantitative RT-PCR, MTT determination, 3H thymidine incorporation, flow cytometry and electron microscopy were used to study the effects of antisense oligodexynucleotide (ODN) targeted against insulin-like growth factor 1 receptor (IGF1R) gene on IGF1R gene expression, drug sensitivity, proliferation and apoptosis of T24 cells. RESULTS: After being treated with antisense ODN specific for IGF1R gene for 48 hours, the intrinsic IGF1R mRNA expression of T24 cells reduced approximately by 72.9%, which caused decrease in survival and increased sensitivity to mitomycin-induced apoptosis(P < 0.05). CONCLUSION: To block the autocrine loop with IGF1R antisense oligonucleotide may serve as a potential therapeutic approach to bladder cancer.

Apoptosis↗

PubMed2000

[Comparison of HLA class I typing by serology with DNA typing].

OBJECTIVE: To compare HLA class I typing by serology with PCR-SSP method in the Chinese population. METHODS: HLA-A and -B antigens were typed by serology with microlymphocytotoxicity and DNA typing with PCR-SSP in 525 clinical samples. Reliability, reproducibility and clinical practicability of both methods were compared according to the typing results. RESULTS: Serological typing for HLA class I was rapid and simple, costing 3 hours. The discrepancy rate between serology and PCR-SSP for HLA-A antigen was 9.0%, consisting of 21 antigens being incorrectly interpreted by serology and 26 of serological "blanks" turning out to be definable alleles by DNA typing. The discrepancy rate for HLA-B antigen was 12.2%, containing 39 antigens being incorrectly interpreted and 35 of serological "blanks" turning out to be definable alleles by PCR-SSP typing. DNA typing for HLA class I by PCR-SSP proved to be an accurate, reliable and well-reproducible technique within 5 hours. While it was difficult to suit clinical assay by a large scale screening because of complicated operation and high technical condition. CONCLUSION: DNA typing for HLA class I by PCR-SSP is suitable for clinical application in the Chinese population with a higher precision than serology. Screening test by serology is recommended. Ambiguous or blank antigens by serology should be retyped by DNA typing.

Adolescent↗

PubMed2000

[HLA-amino acid residue matching in organ transplantation].

OBJECTIVE: To present a new matching policy-HLA amino acid residue matching (Res M) for Chinese population. METHODS: Based on the outcome of genotyping for HLA alleles in massive samples, we presented new Res M according to 10 groups of amino acid residue for class I and, groups of DR/DQ for class II and compared them with HLA six-antigen match program (Ag M). The influence of Res M on early renal function, acute rejection and 1-5 year graft survivals were retrospectively analyzed in 316 cases of first cadaver kidney transplantation. RESULTS: The rate of Res-matched transplants increased greatly. The rate of 0 mismatch (MM) recipients increased from 0.3% by Ag M to 10% by Res M, and that of 0-1 MM transplants from 3.2% to 42.4%. Clinical study showed that 1 - 5 year graft survival with 0 - 1 Res-MM was similar to kidneys with 0 - 2 Ag-MM. Compared to 3 - 4 Res-MM, the early renal function obviously improved (88.8% vs 46.7%), acute rejection decreased (14.9% vs 86.9%), 1 - 5 year survival was increased by 10% - 26% (P < 0.05), and graft survival increased by 14% - 35% (P < 0.01) in recipients with 0 - 1 Res-MM. Cox regression showed that in 10 factors affecting the graft survival, Res-MM was most significant (risk ratio 21.73). CONCLUSION: New Res M has proved to be suitable for clinical application in Chinese population, especially for cadaver kidney transplantation.

Graft Rejection↗

PubMed2000

[Lung injury caused by passive smoking and its effects on cytokines in rats].

OBJECTIVE: A rat model with chronic bronchitis was replicated by passive inhalation of cigarette smoking fume to study its long-term effects on lung injury and nitric oxide (NO), interluekin-6 (IL-6), interleukin-8 (IL-8). METHODS: Levels of nitrogen dioxide (NO(2)) and nitrogen trioxide (NO(3)) were measured with spectrophotometry in rats indicating their level of nitric oxide (NO). Levels of IL-6 and IL-8 were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Levels of NO in serum, bronchial alveolar lavage fluid (BALF) and lung tissue in the smoking group were significantly lower than those in the normal controls (P < 0.01). But, levels of IL-6 and IL-8 were higher in the smoking group than those in the controls. CONCLUSION: Long-term passive smoking could cause injury of lung tissue to certain extent, reduction in secretion of NO in endothelial cells and damage to pulmonary vessels.

Animals↗

PubMed2000

[Linkage analysis of the G6PD gene mutations and its Nla III polymorphic site].

OBJECTIVE: To investigate the molecular and anthropologic features of glucose-6-phosphate dehydrogenase (G6PD) deficiency and the linkage between the Nla III polymorphic site within G6PD gene and three common Chinese G6PD mutations. METHODS: By using denatured gradient gel electrophoresis (DGGE) and allele specific oligonucleotide (ASO) probe dot blot hybridization, Nla III polymorphic site at minus sign13 bp upstream exon 12 within G6PD gene were screened in 54 males with normal G6PD activity and 66 G6PD deficient males. RESULTS: Thirty-two cases with cDNA1376 (G-->T), 21 with cDNA1388 (G-->A) and 13 with cDNA95 (A-->G) were detected in the 66 G6PD deficient males. Among 54 normal controls, T at -13 bp upstream exon 12 within G6PD gene were detected in 11 cases (20.4%, without Nla III polymorphic sites) while C in 43 cases (79.6%, with Nla III polymorphic sites). All 66 G6PD deficient males were linked with C at -13 bp upstream exon 12 (with Nla III polymorphic sites). CONCLUSION: The G6PD mutations cDNA1376 (G-->T), cDNA1388 (G-->A) and cDNA95 (A-->G) were linked with Nla III polymorphism. This feature will play a role in studying the complicated manifestations and anthropology of G6PD deficiency.

Genetic Linkage↗

PubMed2000

[Studies of adsorbents for hemoperfusion--preparation and in vitro studies of cross-linked agar beads entrapped Attapulgite clay].

A new method for preparation of cross-linked agar beads entrapped Attapulgite clay (CAA) is reported. Attapulgite clay was coated with agar and shaped in organic solvent, as well as cross-linked by epichlorohydrin. The products withstood autoclaving at 121 degrees C for 30 minutes and had a good adsorption ability for model compounds and medicines. The results of preliminary investigation indicate that CAA is relatively hemocompatible.

Adsorption↗

PubMed2000

[Studies on the antimutagenic effect of asparagus juice].

Micronucleus (MN) test, sister chromatid exchanges (SCE) and sperm malformation test were used to study the effects of asparagus juice on the mutagenic activity of cyclophosphamide (CP). It was found that, asparagus juice itself showed no effcet on the incidence of MN, SCE and sperm malformation, but asparagus juice reduced the incidence of MN (from 60.0@1000 to 50.3@1000-26.6@1000), SCE (from 29.22 times/cell to 26.40-13.37 times/cell) and sperm malformation (from 61.0@1000 to 51.2@1000-28.6@1000) induced by CP respectively. The inhibitory effects showed a dose dependent relation, which was statistically significant.

Animals↗

PubMed2000

[Epidemiological characteristics of Guillain-Barré syndrome in urban and rural areas in Beijing and Hebei, China].

OBJECTIVE: To investigate epidemiological and clinical patterns of Guillain-Barré syndrome (GBS) in urban and rural areas in Beijing municipality and Hebei province, China. METHODS: We investigated GBS incidence using a strengthened case surveillance and an active case ascertainment in 2 counties and 4 districts of Beijing municipality and 3 counties of Hebei province during 1993 to 1994. RESULTS: On the basis of the diagnostic criteria of NINCDS, 54 patients were identified. The age-adjusted incidence rates per 100,000 population for GBS were 0.9 in rural areas, and 0.8 in urban areas. A peak agespecific incidence showed in adults aged 50 to 59 years. A higher incidence appeared to occur in the spring and summer for rural residents, but not significant for urban population. In comparing course of GBS in rural and urban areas, there were differences in mean days from beginning of neurological symptom to maximal weakness (4.3 vs 7.6 days), and from symptom onset to beginning of recession (11.8 vs 17.5 days). There were preceding events in 72% patients, most frequently in respiratory infection, sensory disturbance in 70.9%, and respiratory assistance in 7.6%. The outcome was compatible with other reports; with complete recovery at 12 months in 79.2% and minimal residua in 20.8% for those alive and with casefatality rate in 7.4%. In addition, a follow-up study on electrophysiological features in 19(90.5%) patients from two counties of Beijing showed the demyelinating lesion (89.5%) over the axonal lesion (52.6%) of motor and/or sensory nerves. CONCLUSIONS: The epidemiological and clinical characteristics of GBS were similar to that reported in other countries. Demyelinating GBS was the main pattern in present population-based study.

Adolescent↗

PubMed1999

Deletion of the Cul1 gene in mice causes arrest in early embryogenesis and accumulation of cyclin E.

The stability of many proteins is controlled by the ubiquitin proteolytic system, which recognizes specific substrates through the action of E3 ubiquitin ligases [1]. The SCFs are a recently described class of ubiquitin ligase that target a number of cell cycle regulators and other proteins for degradation in both yeast and mammalian cells [2] [3] [4] [5] [6]. Each SCF complex is composed of the core protein subunits Skp1, Rbx1 and Cul1 (known as Cdc53 in yeast), and substrate-specific adaptor subunits called F-box proteins [2] [3] [4]. To understand the physiological role of SCF complexes in mammalian cells, we generated mice carrying a deletion in the Cul1 gene. Cul1(-/-) embryos arrested around embryonic day 6.5 (E6.5) before the onset of gastrulation. In all cells of the mutant embryos, cyclin E protein, but not mRNA, was highly elevated. Outgrowths of Cul1(-/-) blastocysts had limited proliferative capacity in vitro and accumulated cyclin E in all cells. Within Cul1(-/-) blastocyst cultures, trophoblast giant cells continued to endocycle despite the elevated cyclin E levels. These results suggest that cyclin E abundance is controlled by SCF activity, possibly through SCF-dependent degradation of cyclin E.

Animals↗

PubMed1999

A bifunctional transposon mini-Tn5gfp-km which can be used to select for promoter fusions and report gene expression levels in Agrobacterium tumefaciens.

A mini-Tn5 transposon derivative, mini-Tn5gfp-km, has been constructed which contained a promoter-less artificial operon consisting of two open reading frames, green fluorescent protein (GFP) and neomycin phosphotransferase II (NptII). When this transposon was used to mutagenize Agrobacterium tumefaciens, all the mutants selected in the presence of kanamycin exhibited GFP expression, which could be conveniently monitored by a fluorometer. The transposon appeared to be bifunctional and could provide both selection and reporter functions. Even the mutants showing minimal levels of GFP expression were still resistant to kanamycin. This suggests that this transposon can be used to select for insertions downstream of both weak and strong promoters, as long as the insertions themselves are non-lethal. This system was used to identify A. tumefaciens genes that were upregulated in response to acidic pH. Screening only 20 colonies led to identification of two promoters that were specifically induced by low pH and one promoter that was specifically induced by acetosyringone in a minimal medium of pH 5.5.

Agrobacterium tumefaciens↗