Biomedical subjects

Xin Ma

Publications and source records attributed to Xin Ma.

46 records · Page 3Linked to original sources

PubMed2003

[Measurement of transient evoked otoacoustic emissions and follow-up of 215 healthy newborns].

OBJECTIVE: To evaluate the characteristics of transient evoked otoacoustic emissions (TEOAE) of healthy newborns and improve hearing screening of newborns. METHOD: To investigate the history of pregnancy and parturition, TEOAE was measured in 425 ears of 215 healthy newborns from 0 to 8 days postpartum and follow-up study was undertaken. RESULT: The general prevalence was 89%. There was some relationship between prevalence and testing time. The average prevalence was 74% in newborns of 0-3 days. The prevalence was 97% in newborns of 4-8 days. The way of parturition, laterality and time of pregnancy over 36 weeks hadn't any significant effect on the prevalence rate. The prevalence of females was higher than males. Quick screen was more sensitive than TEOAE. One ear of hearing loss was diagnosed after follow-up. CONCLUSION: The hearing screening test of newborns should be taken in hospitals after 4 days of birth, the way of parturition had no effect on the cochlear function. The mature time of cochlear hair cells was by the 36th week of pregnancy. Quick screen couldn't take place of TEOAE. Someone who had no TEOAE in one ear or two ears must be followed up and reexamined and exact diagnosis could be made as soon as possible combining with ABR.

Adult↗

PubMed2003

[Trans-external ear canal blow oxygen method].

OBJECTIVE: To study a new method for the treatment of the glue ear and the other out and middle ear diseases. METHOD: 28 ears of the glue ear were treatment with blow oxygen method trans-external ear canal after myringotomy with grommet insertion. The results were compared with that of only tube insertion group of 20 ears in same period. This method were also used to treatment the patients with otitis media after mastoidectomy to compared the effect on dry ear time. RESULT: The therapy time of the blow oxygen group for glue ear were 1.20 +/- 0.42 days, and the control group were 3.50 +/- 0.87 days. The blow oxygen group need only 3.92 +/- 0.77 weeks for dry ear after mastoidectomy. And the control group need 5.82 +/- 2.03 weeks. The results are statistic significant between this two groups. CONCLUSION: The blow oxygen method is a good way for the treatment of glue ear, and can short the time for dry ear after mastoidectomy.

Adolescent↗

PubMed2003

[Construction of a tRNAVal promoter plasmid expressing shRNAs in mammalian cells which mediates RNA interference].

OBJECTIVE: Constructing a plasmid containing tRNAVal promoter to express shRNA which mediates RNA interference. METHODS: A tRNAVal gene was amplified from human genomic DNA by PCR and replaced the last several bases of 3' end by a linker. The tRNAVal promoter after artificial mutation followed a shRNA sequence to luciferase was cloned into pUC18, Puc-tRNAVal, lucRi Cotransfected with pMAMneoLuc into BHK-21 cell to detect the effect of luciferase expression. RESULTS: pUC-tRNAVallucRi suppressed the luciferase expression from pMAMneoLuc by 97.9%-9.5%. CONCLUSION: The results showed that the tRNAVal shRNA plasmid could efficiently suppress luciferase expression in BHK-21.

Animals↗

PubMed2002

Ethnic divergence and linkage disequilibrium of novel SNPs in the human NLI-IF gene: evidence of human origin and lack of association with tuberculosis susceptibility.

Sequence variation in the human genome has been used as a tool in studying human diseases and the evolutionary history of man. A human inherited predisposition to tuberculosis has been suggested and studied; however. genetic mechanisms are still ambiguous. In the present study, we scanned the regulatory and coding region of Nuclear LIM Interactor-Interacting Factor gene (NLI-IF), which is physically close to the tuberculosis-associated gene NRAMP1. Thirteen biallelic single-nucleotide polymorphisms (SNPs) were identified from four ethnic populations (African-American, Caucasian, Hispanic, and Asian) with population-specific distribution of alleles. The extent of linkage disequilibrium (LD) between 402T > C, and 472-42G > A varied distinctly from complete LD in the non-African-American groups to strong but incomplete LD in African-Americans. Both SNPs were in significant LD with the polymorphism 3' UTR in NRAMP1 among these ethnic groups (P < 0.02), except 402T > C in African-Americans. In a case-control study with a Caucasian population, three cosmopolitan SNPs (204C > A, 402T > C and 472 - 42G > A) in NLI-IF showed no significant association with human susceptibility to tuberculosis. Our results support the "out-of-Africa" model of human origin, and suggest the time for the common ancestor dispersing from Africa could not have been more than approximately 385,620 years ago.

Alleles↗

PubMed2002

Genetic status of cell cycle regulators in squamous cell carcinoma of the oesophagus: the CDKN2A (p16(INK4a) and p14(ARF) ) and p53 genes are major targets for inactivation.

We determined inactivation of the CDKN2A (p16(INK4a) and p14(ARF)) gene in 21 cases of oesophageal squamous cell carcinoma (OSCC). The tumours were also analysed for mutations in exons 5-8 and allelic losses in the p53 gene. In addition, we screened the CDKN2B (p15 INK4b), CDKN2C (p18 INK4c), CDK4 and p53R2 genes for mutations in the tumour tissues. Besides concomitant alterations in the CDKN2A and p53 loci in more than half of the cases, our results showed that in 18 OSCC (86%) the CDKN2A (p16(INK4a) and p14(ARF) ) gene was affected through mutations, homozygous/hemizygous deletions and promoter hypermethylation. Eight out of 10 tumours with mutations or promoter hypermethylation specific to the CDKN2A/p16 INK4a gene showed loss of the wild-type allele. One tumour with a single base deletion in the N-terminus (codon 8) of the CDKN2A/p16(INK4a) gene carried a novel germ-line mutation or a rare polymorphism (Ile51Met) in exon 2 of the CDK4 gene. Promoter hypermethylation in the CDKN2A/p14 ARF gene was detected in 11 tumours. In the p53 gene 15 mutations were detected in 14 tumours. We detected an inverse relationship between CDKN2A/p16 INK4a inactivation and frequency of loss of heterozygosity at the p53 locus (OR 0.09, 95% CI 0.01-0.98; Fisher exact test, P-value approximately 0.03). Screening of nine exons of the p53R2 [Human Genome Organisation (HUGO) official name RRM2B] gene resulted in identification of a novel polymorphism in the 5' untranslated region, which was detected in four cases. Our results suggest that the CDKN2A (p16(INK4a) and p14(ARF) ) and p53 genes involved in the two cell cycle pathways are major and independent targets of inactivation in OSCC.

5' Untranslated Regions↗

PubMed2002

Molecular epidemiology of VHL gene mutations in renal cell carcinoma patients: relation to dietary and other factors.

Carcinogenic chemicals act through DNA damage and mitogenic effects. No established mechanism explains the cancer preventive effects, if any, of food items, such as vegetables and fruit. If such data were available, preferably on tumor-initiating genes, the evidence for the protective effects would become stronger. The von Hipple-Lindau (VHL) gene is the tumor suppressor gene predisposing to both sporadic renal cell carcinoma (RCC) and von Hippel-Lindau disease. We have earlier analyzed VHL mutations in RCCs from 102 Swedish patients identified in a case-control study and here examine associations between patient characteristics, including dietary habits and mutations, considering the type of mutation. The results are given as odds ratios (OR), separately for smokers and all patients. In univariate analysis, consumption of vegetables and citrus fruit decreased the frequency of VHL mutations among smokers and citrus fruit among all patients. In multivariate analysis of smokers' characteristics, welding fumes showed a risk of 5.63 for multiple VHL mutations. In smokers, citrus fruit decreased the OR of GC to AT mutations to 0.13 and that of multiple mutations to 0.17; vegetables decreased the OR for single mutations to 0.22. Among all subjects, welding fumes were a risk factor and citrus fruit a protective factor. Additionally, an intake of selenium protected against multiple mutations. The present results provide evidence that the intake of vegetables, selenium and particularly of citrus fruit protects the renal VHL gene from mutational insults that may be endogenous or common in a population. Even though most of the associations are biologically plausible, and vegetables and fruit were an a priori hypothesis, fortuitous results cannot be ruled out in this relatively small study.

Adult↗

PubMed2002

The development of science achievement in middle and high school. Individual differences and school effects.

Using data from the Longitudinal Study of American Youth (LSAY), hierarchical linear models (HLMs) were used to model the growth of student science achievement in three areas (biology, physical science, and environmental science) during middle and high school. Results showed significant growth in science achievement across all areas. The growth was quadratic across all areas, with rapid growth at the beginning grades of middle school but slow growth at the ending grades of high school. At the student level, socioeconomic status (SES) and age were related to the rate of growth in all areas. There were no gender differences in the rate of growth in any of the three areas. At the school level, variables associated with school context (school mean SES and school size) and variables associated with school climate (principal leadership, academic expectation, and teacher autonomy) were related to the growth in science achievement. Initial (Grade 7) status in science achievement was not associated with the rate of growth in science achievement among either students or schools in any of the three areas.

Adolescent↗

PubMed2002

[Inhibition of Luciferase expression in mammalian cells by AAV vector plasmid mediated Luciferase shRNA].

OBJECTIVE: Constructing a plasmid containing the shRNA of luciferase to suppress the expression of luciferase in BHK-21 cell. METHODS: A 334 bp human U6 snRNA promoter was amplified from human genomic DNA by PCR and ligated to a 21 bp reverse repeated motif of luciferase target sequence with 9 bp spacer and AAV plasmid pSNAV. The recombinant pSNAV/U6/Luc plasmid cotransfected with pMAMneoLuc or transfected luciferase cell line to detect the effect of luciferase expression separately. RESULTS: pSNAV/U6/luc suppresses the luciferase expression from pMAMneoLuc by 50% and luciferase cell line by 70%. CONCLUSIONS: The results showed that the short hairpin RNA of luciferase can efficiently suppress its expression in BHK-21.

Cell Line↗

PubMed2002

Training and pretreatment planning of interventional neuroradiology procedures--initial clinical validation.

A PC based system for simulating image-guided interventional neuroradiological procedures for physician training and patient specific pretreatment planning is described. The system allows physicians to manipulate and interface interventional devices such as catheters, guidewires, stents and coils within 2-D and hybrid surface and volume rendered 3-D patient vascular images in real time. A finite element method is employed to model the interaction of the catheters and guidewires with the vascular system. Fluoroscopic, roadmapping and volume rendered 3-D presentations of the vasculature are provided. System software libraries allow for the use of commonly employed catheters, guidewires, stents and occluding coils of various shapes and sizes. The results of an initial clinical validation suggest that the experience gained from our simulator is comparable with that of using a vascular phantom. We are conducting further validation with the aim of providing patient specific pretreatment planning.

Angioplasty, Balloon↗

PubMed2001

Participation in Advanced Mathematics: Do Expectation and Influence of Students, Peers, Teachers, and Parents Matter?

Using six waves of data (Grades 7 through 12) from the Longitudinal Study of American Youth (LSAY), this study investigated the effects of expectation and influence of students, peers, teachers, and parents on participation in advanced mathematics. Results of survival analysis indicated a significant decline in participation rate in the transition from Grades 11 to 12. Students with higher future expectation were more likely to participate in advanced mathematics. Peer influence and teacher expectation did not have strong effects, and the effect of student future expectation was independent of peer and teacher effects. The effect of parent expectation and parent college plan for children were strong, and in their presence, the effect of student future expectation declined. Mathematics achievement and attitude toward mathematics were the most important factors affecting participation in advanced mathematics. With control over achievement and attitude, (a) the effect of student future expectation declined, (b) the effects of peer influence and teacher expectation disappeared, and (c) the effects of parent expectation and parent college plan for children were reduced. Copyright 2001 Academic Press.

Journal Article↗