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Biomedical subjects

Yang Chen

Publications and source records attributed to Yang Chen.

82 records · Page 5Linked to original sources
PubMed2002

Electroglottographic evaluation of gender and vowel effects during modal and vocal fry phonation.

Two unique characteristics of vocal fry register are the occurrence of multiple opening and closing phases occurring within one vibratory cycle and a similar vocal fundamental frequency (F0) between women and men. The present study tested the hypothesis that significant differences in glottal cycle symmetry exist between women and men during modal phonation, with no significant differences during vocal fry phonation. Consistent with previous studies of modal phonation, it was also hypothesized that a vowel effect would be apparent during vocal fry phonation. Five women and 5 men sustained modal and vocal fry phonations in four vowel contexts (/a, ae, u, i/). Vocal F0, duration of opening and closing phase, and contact symmetry (speed quotient) were derived from electroglottographic (EGG) waveforms. Both female and male speakers demonstrated significantly higher SQ values in vocal fry register than in their modal register, indicating a longer opening-phase duration per glottal cycle. Women demonstrated a significantly greater increase in SQ during vocal fry phonations than men, indicating greater asymmetry between opening and closing durations. The results confirmed that gender differences in vocal fold contact behavior not only exist during modal register but also during vocal fry register. No vowel effects on vocal fold contact behavior as inferred using the SQ measure were found for either modal or vocal fry registers. Possible contributing factors to multiple opening and closing phases occurring within a vibratory cycle are discussed.

Adult↗
PubMed2002

A Drosophila homologue of Sir2 modifies position-effect variegation but does not affect life span.

Control of chromosome structure is important in the regulation of gene expression, recombination, DNA repair, and chromosome stability. In a two-hybrid screen for proteins that interact with the Drosophila CREB-binding protein (dCBP), a known histone acetyltransferase and transcriptional coactivator, we identified the Drosophila homolog of a yeast chromatin regulator, Sir2. In yeast, Sir2 silences genes via an intrinsic NAD(+)-dependent histone deacetylase activity. In addition, Sir2 promotes longevity in yeast and in Caenorhabditis elegans. In this report, we characterize the Drosophila Sir2 (dSir2) gene and its product and describe the generation of dSir2 amorphic alleles. We found that dSir2 expression is developmentally regulated and that dSir2 has an intrinsic NAD(+)-dependent histone deacetylase activity. The dSir2 mutants are viable, fertile, and recessive suppressors of position-effect variegation (PEV), indicating that, as in yeast, dSir2 is not an essential function for viability and is a regulator of heterochromatin formation and/or function. However, mutations in dSir2 do not shorten life span as predicted from studies in yeast and worms.

Alleles↗
PubMed2002

Relationship between body weight and hematological and serum biochemical parameters in female cynomolgus monkeys (Macaca fascicularis).

Obesity is a risk factor triggering a variety of metabolic diseases. Cynomolgus monkeys (Macaca fascicularis) exhibit spontaneous onset of obesity in adulthood, similar to such onset exhibited by humans. To clarify the characteristics accompanying obesity in female cynomolgus monkeys, we used simple and multiple regression analyses to determine the relationship between body weight and hematological and serum biochemical parameters as well as obesity-related hormones, namely, leptin and insulin. Simple regression analysis showed that body weight was significantly (P < 0.05) correlated with leptin level, insulin level, hemoglobin concentration, hematocrit values, mean corpuscular volume, glucose concentration, and triglyceride concentration. In addition, a multiple regression model containing leptin level, insulin level, mean corpuscular volume, and red blood cell count explained 66.9% of the variance in body weight. Therefore, female cynomolgus monkeys show similar obesity characteristics to humans, i.e., obesity is associated with enhanced synthesis and excretion of leptin in adipocytes, high risk of diabetes mellitus, and high levels of hematocytes. Our results indicate that female cynomolgus monkeys are good models for studying obesity in humans.

Animals↗
PubMed2002

[Effects of exposure to asbestos on plasma activity of glutathione S-transferases].

OBJECTIVE: To understand the effects of exposure to asbestos and GSTM1 genotypes on plasma activity of glutathione S-transferases (GSTs). METHODS: Ninety-four workers exposed to asbestos and 51 controls were selected, and their general information, occupational history and personal behavior were collected by questionnaire. Venous blood specimen was collected from each of them and plasma was separated for detection of GSTs activity and lymphocytes for DNA extraction and GSTM1 genotyping. RESULTS: Plasma activity of GSTs in the asbestos-exposed workers (23.0 +/- 6.9) U/L was significantly lower than that in the controls (32.6 +/- 11.8) U/L, which declined with the length of employment in asbestos industry and the increase of cumulated dose of asbestos. Stratification of workers by GSTM1 genotypes showed that plasma activity of GSTs in asbestos-exposed workers with GSTM1+/+ or GSTM1-/- were (24.0 +/- 6.1) and (22.5 +/- 7.3) U/L, respectively, lower than those in the controls with the same genotypes (38.1 +/- 13.2) and (26.8 +/- 6.6) U/L. Plasma activity of GSTs in the control workers with GSTM-/- was significantly lower than in those with GSTM+/+, and, so did in asbestos-exposed workers, but without statistically significant difference. CONCLUSION: Exposure to asbestos could significantly decrease plasma activity of GSTs, and GSTM1 genotypes could affect on the activity of GSTs in the control workers, which was not so obvious in asbestos-exposed workers.

Adult↗
PubMed2002

[The study on the acoustic features of congenital velopharyngeal insufficiency in 28 patients].

OBJECTIVE: To study the acoustic features of the patients with congenital velopharyngeal insufficiency (CVPI). METHODS: The acoustic features of 28 patients with CVPI were analyzed with the computer speech lab, contrasted by the features of 20 controls. RESULTS: There was significant difference in F2, B2, F3, B3 and VOT between the patients and the controls (P<0.05). It was not same on every syllable; From phonetic images, F1, F2 and F3 of the controls were more clear than those of the patients, the other districts of the controls were lighter than those of the patients. F1 of the patients was darker and broader, their F2 and F3 were lower, weaker and broader. Among F1, F2 and F3 of the patients, there were some extra FORMANTs. Erected stripes and fills before the vowel of the patients were fewer than those of the controls. CONCLUSION: There were apparent distinctions in F2, B2, F3 and B3 between the patients and the controls, and there was significant difference in phonetic images of two groups, especially in FORMANTs, and consonants.

English Abstract↗
PubMed2002

[Clinical practice of behavior therapy in speech treatment].

OBJECTIVE: To apply behavior therapy to treat patients with velopharyngeal insufficiency(VPI),with the aim of improving speech treatment. METHODS: 20 patients(10 male, 10 female,ranged from 4.0 to 38.4 years, mean age 17.8 years)with VPI were available for this study. Of 20 patients, 5 with congenital velopharyngeal insufficiency,10 with posterior pharyngeal flap,5 with palatoplasty. Behavior therapy was adopted in speech treatment. The quantitative measurement of Chinese speech intelligibility and blowing test was carried out before speech therapy and after speech therapy. RESULTS: The effect of behavior therapy in speech treatment was satisfied. Their Chinese speech intelligibility and blowing test after speech therapy were obviously better than before. CONCLUSION: The behavior therapy is a very effective method in speech in treatment, but it was important to select indications and treat individually.

English Abstract↗
PubMed2001

Identification of the High-Lying Pi Component of NiF by Laser-Induced Fluorescence.

The laser-induced fluorescence excitation spectrum of jet-cooled NiF has been studied in the range 435-570 nm. Eight electronic transitions, involving four high-lying Pi components and two lower states, the ground state X(2)Pi(3/2), and the low-lying state [0.25](2)Sigma, respectively, have been recorded. Two new Pi components are identified for the first time and their rotational constants are determined. The [20.4]Pi(3/2) component is assigned as the v'=1 level of the previously known [19.7](2)Pi(3/2) state. The [20.3]Pi(3/2) component may be linked to the component of an unreported quartet state. The previously reported [20.0](2)Pi(1/2) component is reassigned as a subcomponent of (2)Delta. Copyright 2001 Academic Press.

Journal Article↗
PubMedDate not supplied

Generic bioaffinity silicone surfaces.

Synthetic polymer surfaces require surface modification to improve biocompatibility. A generic route to biocompatible silicone elastomers is described involving high yield surface functionalization of standard silicones with hydrosilanes, hydrosilylation using asymmetric, allyl-, NSC-terminated PEO of narrow molecular weight, and covalent modification in one step with amine-containing biological molecules including oligopeptides (YIGSR, RGDS), proteins (EGF, albumin, fibrinogen, mucin), and glycosaminoglycans (heparin). Efficient, high-density binding (e.g., 0.2 EGF molecules/nm2) was demonstrated using radiolabeling studies. The resulting surfaces were demonstrated to be biocompatible by further reaction with biomolecules, for example, thrombosis suppression on surfaces modified by heparin + ATIII, and the formation of confluent corneal epithelial cell layers on EGF, RGDS, or YIGSR surfaces.

Biocompatible Materials↗
PubMedDate not supplied

Speaking rates of American and New Zealand varieties of English.

Various acoustic measures of speaking rate were calculated for 40 adult speakers of New Zealand English (NZE). These measures were then compared to a group of 40 adult speakers of American English (AE). Results of the analysis identified significantly faster overall speaking rate and articulation rate for the NZE group compared to the AE group. No gender differences in speaking rate or articulation rate were found for either variety of English. The observed differences in rate between AE and NZE are interpreted with regard to diverse vowel production patterns between the varieties, as well as possible differences in rhythmic timing patterns. The impact of differences in speaking rate between varieties of English on the assessment and treatment of speech timing disorders is discussed.

Adolescent↗