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Biomedical subjects

X Ma

Publications and source records attributed to X Ma.

At least 109 records · Page 6Linked to original sources
PubMed2001

[Effect of Shajiang black soil amended by coal fly ash on ecological factors and residue of heavy metal in wheat field].

The effect of Shajiang black soil amended by coal fly ash on ecological factors in wheat field and residua of Cd, Cr, Pb, Hg and As were studied by pot experiment. The results showed that applying coal fly ash into Shajiang black soil could decrease soil density, soil proportion and clay content, but increase soil porosity, filtration coefficient and soil temperature. Moreover, it could promote water evaporating when soil moisture was high and keep soil water when lower than 10%. It also could facilitate activity of soil micro-organism and promote soil nutrient transforming. With (6-18) x 10(4) kg.hm-2 coal fly ash applied in Shajiang black soil, the accumulated quantity of Cd, Cr, Pb, Hg and As in soil and in wheat grain were lower than international standard index of pollution. Therefor, Shajiang black soil amended by coal fly ash was safe and reliable within the above range.

Coal↗
PubMed2001

[Interleukin-1 increase nitric oxide synthesis through up-regulation of inducible nitric-oxide synthase by rabbit mandibular condylar cartilage cells in vitro].

OBJECTIVE: To investigate the influence of IL-1 on the biosynthesis of nitric oxide by rabbit mandibular condylar cartilage (MCC) cells. METHODS: MCC cells of white rabbits were harvested enzymatically and cultured in DMEM supplemented with 0.4% newborn calf serum. In the experiment, a variety of concentrations of IL-1 were added to the medium. NO production was determined as nitrite accumulation in the medium. The effects of IL-1 on the mRNA levels of inducible nitric-oxide synthase (iNOS) were assessed by mRNA in situ hybridization method. RESULTS: IL-1 can significantly increase nitric oxide synthesis by MCC cells in a concentration-dependent manner. In addition, normal MCC cells had light expression of iNOS expression and IL-1 (10-100 micrograms/L) promoted the expression of iNOS. CONCLUSIONS: IL-1 can inhibit the chondrocytes proliferation and induce apoptosis that might be through the way of up-regulation of iNOS expression.

Animals↗
PubMed2001

Detection of human herpesvirus 8 DNA in acute leukemia patients.

OBJECTIVE: To determine the prevalence of human herpesvirus 8 (HHV-8) DNA in acute leukemia (AL) patients. METHODS: The presence of HHV-8 DNA sequences in peripheral blood mononuclear cells (PBMC) and bone marrow mononuclear cells (BMMC) from 50 AL patients was examined using polymerase chain reaction (PCR). Nine human hematopoietic cell lines and PBMC from 30 normal donors were also included. RESULTS: HHV-8 DNA sequences were detected in one case of acute myelogenous leukemia (AML). The specimens from the bone marrow aspirate, peripheral blood and serum of this patient were all positive. None of the normal donors and human hematopoietic cell lines showed evidence of HHV-8 DNA. CONCLUSION: The results suggest that the prevalence of HHV-8 is low in AL in China.

Acute Disease↗
PubMed2001

[Phosphorylation of gap junction gene connexin 43 protein and dissociated calcium in HeLa cell line by all-trans-retinoic acid].

OBJECTIVE: To investigate the regulation effect on signal transduction pathway of gap junction gene connexin (Cx)43 in human cervical carcinoma cell line HeLa by all-trans-retinoic acid(ATRA). METHODS: Cell culture, Fluo-3 AM loading and laser scanning confocal microscope, flowcytometer(FCM) and western blot were employed to detect expression and regulation effect on signal transduction pathway of gap junction gene connexin Cx43 in HeLa cells by retinotic acid(RA). RESULTS: After treated with ATRA, the intercellular second messenger dissociated calcium ([Ca2+]i) was much higher in HeLa cells (58.16 mumol/L) than untreated cell (35.73 mumol/L). A detectable and up-regulation of Cx43 of 43,000 protein in HeLa cells increased from 1.9% to 26.3% in RA-treated cells than untreated cell examined by FCM and western blot. Immunoblot analysis showed that only the treated cells had phosphorylated form of Cx43 protein. CONCLUSION: The anti-tumor effect of ATRA in HeLa cells might be due to up-regulation of Cx43 gene and its signal transduction pathway which medials gap junction intercellular communication.

Calcium↗
PubMed2001

[Association of vascular endothelial growth factor expression with angiogenesis and tumor cell proliferation in human lung cancer].

OBJECTIVE: To evaluate the expression of vascular endothelial growth factor (VEGF) and the relation with angiogenesis and tumor cell proliferation in human lung cancer. METHODS: Expression of VEGF, angiogenesis, tumor cell proliferation in 63 cases of human lung cancer were examined immunohistochemically. Anti-VEGF(165)-Ab3 was used for VEGF expression, a monoclonal antibody directed against CD(34) to identify intratumoral microvessel density (iMVD) and the proliferating cell nuclear antigen (PCNA) as a marker of proliferating tumor cells. RESULTS: Positive staining for VEGF was obtained in 32 of the 63 cases (50.8%), iMVD varied from 4 to 138.7 (M = 36)/x 400 and the proportion of PCNA positive cells varied from 0 to 92% (M = 25.03%). iMVD in high-grade VEGF tumors was significantly higher than that in VEGF-negative tumors and low-grade VEGF tumors. PCNA labeling proliferation index in small cell lung cancer was higher than that in non-small cell lung cancer. iMVD significantly increased with increasing VEGF expression. CONCLUSION: There is VEGF expression in lung cancer. VEGF expression is significantly associated with iMVD, but there is no association between iMVD or VEGF expression and PCNA expression. There is no association between VEGF expression and histological classification and clinical stages.

Adult↗
PubMed2001

[A study of mutation(s) of the epithelial sodium channel gene in a Liddle's syndrome family].

OBJECTIVE: To study the genetic mechanism of Liddle's syndrome in a family and help the diagnosis (specially ante-natal) and treatment of Liddle's syndrome clinically. METHODS: (1) Physical examination and measurement of serum potassium, plasma aldosterone and renin activity respectively by biochemical and radioimmunological assays were made for the member of the family. (2) Venous blood samples were collected from the members of the family and total genomic DNA was prepared. One set of specific primers was used for direct polymerase chain reaction, for amplifying C terminus of beta-subunit of epithelial sodium channel (hbetaENaC). Polymerase chain reaction products were subjected to single-strand conformation polymorphism and direct DNA sequence analysis. RESULTS: A new frameshift mutation (1bp, INS, 600G) of the gene of C terminus of beta-subunit of hbetaENaC was found in the Liddle's syndrome family. This mutation introduced a new stop codon at position 605 and deleted the last 34 normal amino acids from the C teminus of hbeta ENaC. Eight genetically affected subjects had severe hypertension and suppressed levels of plasma aldosterone and plasma renin activity; half of them had hypokalemia. CONCLUSION: The frameshift mutation (1bp, INS, 600G) of hbetaENaC gene is the likely cause of Liddle's syndrome in this Chinese family.

Adolescent↗
PubMed2001

[Study on the pitting corrosion-resistant of Ti-75 alloys with different from oxidize temperatures in vacuum in oral cavity].

OBJECTIVE: To study the property of pitting corrosion-resistant of Ti-75 alloys with different from oxidize temperatures in vacuum in oral. METHODS: Ti-75 alloys were prepared 30 mm x 10 mm x 1 mm specimens and annealed at 200 degrees C, 300 degrees C, 400 degrees C, 500 degrees C oxidize temperatures in vacuum. The open-circuit potential (Ecoor) and the breakdown potential (Eb) were measured, and the cyclic anodic polarization curves was drawn. RESULTS: The Ecoor of Ti-75 alloys annealed at 200 degrees C oxidize temperatures in vacuum is -49.0 mV. At 300 degrees C, 400 degrees C, 500 degrees C oxidize temperatures in vacuum, the different Ecoor is -75.3 mV, -51.3 mV and -60 mV respectively. The Eb of Ti-75 alloys annealed at 200 degrees C oxidize temperature for 5 minutes in vacuum is the highest (+180 mV). CONCLUSION: It is better for Ti-75 alloys being annealed at 200 degrees C for 5 minutes in vacuum to release the stress of machine duplication and to resistant pitting corrosion.

Alloys↗
PubMed2001

Clinical and experimental study on facial paralysis in temporal bone fracture.

OBJECTIVE: To study the main prognostic factors and significance of facial nerve decompression for facial paralysis in temporal bone fracture. METHODS: The main relative prognostic factors of 64 patients with facial paralysis were analyzed. An experimental model of facial paralysis was made. The expansion rates of facial nerve in the facial canal opening group and the facial canal non-opening group were measured and observed under electron microscope. RESULTS: The main factors affecting the prognosis were facial nerve decompression and selection of surgery time. The expansion rate of facial nerve in the facial canal opening group was significantly higher than that of the facial canal non-opening group (t=7.53, P<0.01). The injury degree of the nerve fiber in the facial canal non-opening group was severe. CONCLUSIONS: Early facial nerve decompression is beneficial to restoration of the facial nerve function.

Animals↗
PubMed2001

[Colon cancer risk factors in Jiashan county, Zhejiang province, the highest incidence area in China].

OBJECTIVE: To investigate the risk factors of colon cancer in the highest incidence area, Jiashan county, providing scientific basis for monitoring and prevention. METHODS: With a population-based case-control study, 109 colon cancer patients with 1:7 matched controls were interviewed with uniform questionnaires. Conditional logistic regression was used for univariate and multivariate analysis of colon cancer. RESULTS: Ten years before, high monthly pork consumption (OR = 1.608), high monthly animal oil consumption (OR = 1.391), psychological depression (OR = 9.887), negative emotion (OR = 1.723), lower digestive tract diseases (OR = 4.163), and history of colorectal cancer in the first degree relatives (OR = 3.421) were the main risk factors of colon cancer. At that time, high monthly vegetable consumption was a protective factor for colon cancer (OR = 0.422). CONCLUSION: Colon cancer in Jiashan county was related to dietary factors. The research results support the colon cancer etiological hypothesis of "fat-bile acid" and "deficiency of dietary fibres". Psychological depression, inheritance and lower digestive tract diseases were also correlated with colon cancer.

Case-Control Studies↗
PubMed2001

[Research on achievement on pulsology in Yi bian (Medical bank stone) by He Mengyao].

Yi bian (Medical Bank Stone) was the representative works of He Mengyao, a doctor of the Qing dynasty. There were detailed introduction about pulse in the fifth volume, pulse feeling, including its sites, figures, movements, paused conditions, corresponding with four seasons and five organs, stomach - qi of pulse and pulse conditions referring to various diseases with examples and reasons. Not only was it written in an easy and fluent style reasonably and colorfully, but also the words were arranged clearly and beautifully.

Books↗
PubMed2001

[Culture and cryopreservation of human mandibular condylar cartilage cells].

OBJECTIVE: To establish an effective way in cryopreserving mandibular condylar cartilage cells. METHODS: Human mandibular condylar cartilage (MCC) cells were harvested and amplified by microcarrier culture technique. MCC cells were preserve in liquid nitrogen. The biological properties of cryopreserved MCC cells were investigated. RESULTS: Cells from liquid nitrogen preservation kept their phenotypic, proliferative an metabolic characteristics of MCC cells in vivo. CONCLUSIONS: Cryopreservation of MCC cells can supply adequate qualified cells for repairing the defects of mandibular condyle cartilage and temporomandibular joint disk.

Cartilage↗
PubMed2001

[K. pneumoniea endotoxin induced mice beta-defensin-4 mRNA expression and its signaling transduction].

OBJECTIVE: To investigate the in vivo effects of Klebsiella pneumoniae endotoxin(LPS) on beta-defensin expression and the relevant signaling transduction pathway. METHODS: A LPS tolerant mouse C3H/HeJ with a point mutation at Toll-like receptor-4 (TLR4) gene and its wild type strain C3H/HeN were used in this study. C3H/HeJ and C3H/HeN were injected with 4 mg/kg of LPS intraperitoneally. The tracheas, lungs and kidneys of the C3H/HeJ and C3H/HeN were collected respectively at different LPS-treated time points, and the total RNA of each sample was extracted. The expression of mice beta-defensin-3 and/or beta-defensin-4 mRNA in these tissues was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The sequence of cDNA amplified from the lung of C3H/HeN treated by LPS for 24 h was analyzed. By using western blot, p-I kappa B alpha (phosphorylated I kappa B alpha) and I kappa B alpha of in the lungs of C3H/HeJ and C3H/HeN were detected at different time points after treatment with LPS or without LPS. RESULTS: 1. beta-defensin-4 mRNA was detected in the lungs of C3H/HeN after 24 h treatment with LPS. In contrast, no signal was determined in C3H/HeJ mice with LPS treatment and the C3H/HeN mice without LPS treatment. 2. Compared with the control, increas of the p-I kappa B alpha was observed in the lungs of C3H/HeN at 4 h after treatment with LPS, while both the p-I kappa B alpha and I kappa B alpha contents showed a tendency to go down at 8 h after treatment and dramatically decreased at 24 h. But there were no changes in the of p-I kappa B alpha and I kappa B alpha content the lungs of C3H/HeJ under the same conditions. CONCLUSION: K. pneumoniea endotoxin could induce the expression of beta-defensin-4 mRNA in the lung of C3H/HeN, and TLR4-mediated NF-kappa B activation signaling pathway may be responsible for this event.

Amino Acid Sequence↗
PubMed2001

[The clinical characteristics of adhesive type cholesteatoma].

OBJECTIVE: To study the clinical characteristics of adhesive type cholesteatoma. METHODS: Fifty-two cases (52 ears) of adhesive type cholesteatomas were reviewed. Of the 52 cases there were 30 males and 22 females; 24 left ears and 28 right ears. The age of the patients ranged from 8 to 70 years. All of the patients were treated by tympanoplasty, and the open and close methods were performed in 37 ears and 10 ears, respectively. Other methods were employed in the remaining 5 cases. Nine ears underwent tympanoplasty type "O" without ossicular re-construction for an increase in the threshold of the bone conduction. Types I, III and IV tympanoplasties were performed in 1, 16 and 26 ears, respectively. RESULTS: The structures of the upper parts of the stapes had disappeared in 25 ears, which was significantly higher in this series than that in the attic type cholesteatoma. The over-all recovery rate of hearing was 69.8%, while 75.9% and 55.6% in the open and closed tympanoplasties, respectively. Postoperative complications of perforations and re-adhesions of the tense part of the tympanic membrane were observed in 3 and 4 ears, respectively. CONCLUSIONS: Adhesive type cholesteatoma is not uncommon. The cause of this disease may be the functional defects in the pharynotympanic tube. A thorough and effective treatment for the secretory otitis media is crucial for the prevention of adhesive type cholesteatomas. The open method tympanoplasty was considered as the first choice for adhesive type cholesteatoma while the closed method must be great careful.

Adolescent↗
PubMed2001

[The spectroscopic study of the iodine beta-cyclodextrin complexes].

In this paper, the iodine beta-cyclodextrin complexes prepared in different techniques were investigated by Fourier transformation infrared spectrum(FTIR), FT-Raman, Ultra-violet absorption spectrum in qualitative and quantitative analysis. Results showed that the iodine existed in dissociated, bundle and polymerized forms in the complexes. Contras to the method of alcohol craft, the sample prepared in water craft method included a higher capacity of iodine, but it was not stable enough to keep a constant high iodine concentration. This analysis method was simple and convenient, it is useful for quality control of the iodine beta-cyclodextrin complexes raw material medicine.

Anti-Infective Agents↗
PubMed2000

Single nucleotide polymorphism analyses of the human proliferating cell nuclear antigen (pCNA) and flap endonuclease (FEN1) genes.

The products of proliferating cell nuclear antigen (PCNA) and flap endonuclease (FEN1) genes are multifunctional proteins that are involved in DNA replication and damage repair. Yeast models suggest association of mutant forms of PCNA and FEN1 with genomic instability. In our study, we have determined the single nucleotide polymorphisms in human PCNA and FEN1 genes. We sequenced the coding region and adjacent noncoding region of both the PCNA and FEN1 genes in 120 alleles (60 individuals). In the PCNA gene, we detected 9 sequence variants with Hardy-Weinberg allele frequency ranging from 0.008 to 0.088. No polymorphism was detected in the FEN1 gene. The sequence variants in the PCNA gene included 7 intronic single nucleotide polymorphisms (SNP) and 2 synonymous exonic SNPs. All the intronic SNPs were located in introns 1 and 4, which contain several regulatory elements involved in the control of PCNA gene expression. Six of the 7 intronic SNPs showed complete linkage disequilibrium. We confirmed this allelic linkage disequilibrium by allele-specific PCR sequencing. We genotyped 117 additional individuals belonging to 3 population subgroups using the PCR-RFLP method. Finally, to see if the detected polymorphisms are associated with any cancer type, we genotyped cases with melanomas (37 cases), breast cancers (118 cases) and lung cancers (100 cases). We did not find statistical difference in frequency of polymorphism in any cancer type compared with healthy controls, although in breast cancer the frequency was low. Our results suggest that the coding regions of the PCNA and FEN1 genes are highly conserved when compared with other DNA repair genes. The potential of some of the detected intronic polymorphisms to effect regulation of the PCNA gene expression remains to be determined.

Alleles↗
PubMed2000

The corticofugal system for hearing: recent progress.

Peripheral auditory neurons are tuned to single frequencies of sound. In the central auditory system, excitatory (or facilitatory) and inhibitory neural interactions take place at multiple levels and produce neurons with sharp level-tolerant frequency-tuning curves, neurons tuned to parameters other than frequency, cochleotopic (frequency) maps, which are different from the peripheral cochleotopic map, and computational maps. The mechanisms to create the response properties of these neurons have been considered to be solely caused by divergent and convergent projections of neurons in the ascending auditory system. The recent research on the corticofugal (descending) auditory system, however, indicates that the corticofugal system adjusts and improves auditory signal processing by modulating neural responses and maps. The corticofugal function consists of at least the following subfunctions. (i) Egocentric selection for short-term modulation of auditory signal processing according to auditory experience. Egocentric selection, based on focused positive feedback associated with widespread lateral inhibition, is mediated by the cortical neural net working together with the corticofugal system. (ii) Reorganization for long-term modulation of the processing of behaviorally relevant auditory signals. Reorganization is based on egocentric selection working together with nonauditory systems. (iii) Gain control based on overall excitatory, facilitatory, or inhibitory corticofugal modulation. Egocentric selection can be viewed as selective gain control. (iv) Shaping (or even creation) of response properties of neurons. Filter properties of neurons in the frequency, amplitude, time, and spatial domains can be sharpened by the corticofugal system. Sharpening of tuning is one of the functions of egocentric selection.

Animals↗
PubMed2000

The Molecular Spreading of Nonpolar Perfluoropolyether Films on Amorphous Carbon Surfaces.

The spreading mechanism of nonpolar perfluoropolyether films on carbon surfaces is examined in the mesoscopic regime, including both submonolayer and multilayer films. For the submonolayer film, adsorption-desorption is a main mechanism for spreading, and the surface diffusion coefficients increase as the film thickness increases. The driving force for the spreading in the submonolayer regime is the gradient of the disjoining pressure, which is described by the two-dimensional virial equation. For the multilayer film regime, the spreading characteristics are determined by the molecular weight and the disjoining pressure gradient, which is assumed to be purely van der Waals in nature. We adopt a partial slip boundary condition to analyze the multilayer film, which qualitatively explains the dependence of the surface diffusion coefficient on film thickness. Copyright 2000 Academic Press.

Journal Article↗