Biomedical subjects

Jun Yang

Publications and source records attributed to Jun Yang.

At least 397 records · Page 22Linked to original sources

PubMed2002

Possible function of outward potassium currents in isolated Deiters' cells of guinea pig cochlea.

OBJECTIVE: To study potassium currents in isolated Deiters' cells of guinea pig cochlea and explore possible function of potassium current in Deiters' cell. METHODS: The whole cell patch clamp recording technique was used to study potassium currents of Deiters' cells in normal external solution and solutions with different K(+) concentrations. We also studied the effects on reversal potentials and outward potassium currents. RESULTS: Isolated Deiters' cells possess voltage dependent, outwardly rectifying ion channels, which are K(+) selective. 50 mmol/L K(+) and 150 mmol/L K(+) in external solution reduced I(K-max) from (10.06 +/- 2.2) nA (n = 13) in normal external solution to (6.43 +/- 1.67) nA (n = 6, P < 0.05) and (5.49 +/- 1.33) nA (n = 6, P < 0.05), respectively. While the amplitude of tailcurrents decreased from (468.76 +/- 61.76) pA in 5 mmol K(+) external solution to (224.74 +/- 35.89) pA (P < 0.05) in 50 mmol/L K(+) and to (-911.59 +/- 78.17) pA (P < 0.01) in 150 mmol/L K(+) external solution. CONCLUSIONS: Outwardly rectifying potassium in Deiters' cells could buffer extracellular K(+) in the small space between Deiters' cells and outer hair cells or neural fibers and participate in the diffusion of K(+) from endolymph to perilymph.

Animals↗

PubMed2002

[Outwardly rectifying potassium currents in isolated outer hair cells in cochlea of guinea pig].

OBJECTIVE: The purpose of this study was to investigate electrophysiological properties of isolated outer hair cells (OHCs) from cochlea of the guinea pig, record outwardly rectifying potassium currents in OHCs with different length, analyze component of outwardly rectifying potassium currents, study kinetics of the currents. METHOD: The whole cell patch-clamp technique was used. RESULT: Whole-cell capacitance of the OHC was (30.96 +/- 2.79) pF(n = 29), zero current potential was (30 +/- 2.1) mV(n = 16) and reversal potential was (-51.67 +/- 1.84) mV(n = 9). Variation in expression of outwardly rectifying potassium currents was found in OHCs with different length, namely, potassium conductance was greater in short OHC than in tall OHC. The maximal amplitude of outwardly rectifying potassium currents were reduced by 60% in the presence of 100 mumol/L CdCl2 and change the kinetics of the currents, effects of CdCl2 on the peak currents were greater when compared to the effects on the steady-state currents (P < 0.01, n = 5). 1 mmol/L 4-aminopyridine (4-AP) inhibited 43% of the maximal amplitude of the currents and had no effect on the kinetics of the currents. Activation of the currents was described by Boltzmann equation, V1/2 = (-11.07 +/- 0.26) mV, S = (6.62 +/- 1.74) mV(n = 13). CONCLUSION: Outwardly rectifying potassium currents were composed of calcium-activated potassium current, outward delayed rectifier potassium current and A type current.

Animals↗

PubMed2002

[Lab-on-a-chip (microfluidics) technology].

Over the last decade, the lab-on-a-chip concept has received considerable attention. This technology promises significant advantages in terms of speed, cost, sample/reagent consumption, contamination, efficiency and automation. In this review, we focus on lab-on-a-chip with fluid flow along micro-scale channels (microfluidics) and its application on life science and biotechnology.

Chemistry Techniques, Analytical↗

PubMed2002

[Prevalence of overweight and obesity in Chinese middle-aged populations: Current status and trend of development].

OBJECTIVE: To understand the current status on prevalence of overweight and obesity in Chinese middle-aged population, and to quantify the magnitude of the trends of development in the past two decades. METHODS: Body mass index (BMI) was measured on 15 389 middle-aged men and women from 15 natural populations all over China with different geographical, economical (urban/rural) and occupational status. Overweight was defined as BMI >/= 25 while obesity as BMI >/= 30. RESULTS: 1) The rates of prevalence on overweight and obesity varied dramatically between populations. 2) In general, the prevalence rates were higher in the northern areas, in urban areas, and in women. 3) The current problem of obesity was related to 'pre-obese' stage, with less than 10% in most populations. 4) The prevalence of overweight and obesity started to show significantly increase from early 80's to early 90's but more prominant in the late 90's. CONCLUSION: Prevention and intervention of overweight and obesity are in urgent need in the Chinese populations, especially in those economically fast developing areas.

Adult↗

PubMed2002

[A prospective study on body mass index and mortality].

OBJECTIVE: To assess the relationship between body mass index (BMI, weight in kilograms divided by the square of height in meters) and both all-causes mortality and mortality from specific cause. METHODS: Cardiovascular disease (CVD) risk factors were studied in 1982 - 1985 on more than 30 thousands participants aged 35 - 59 from 10 Chinese populations. 30 560 participants (15 723 for men, 148 837 for women) without known myocardial infraction, stroke or cancer was followed from 1999 to 2000. All-causes of death were documented. RESULTS: Three thousand two hundred and twelve death cases occurred during follow-up of average 15.2 years, including 676 CVD (coronary heart disease and stroke) deaths, 1 281 cancer deaths and 1 255 deaths for other reasons. Cox proportional hazards model adjusting age and gender showed that the relative risks of all causes of death in groups of low BMI (BMI < 18.5), normal BMI (BMI from 18.5 to 23.9), overweight (BMI from 24 to 27.9) and obesity (BMI >/= 28) which were defined according to the strata of BMI for Chinese were 1.21 (95% CI: 1.10 - 1.33), 1.00, 0.91 (95% CI: 0.82 - 1.01) and 1.12 (95% CI: 0.93 - 1.37), respectively ("U" shaped relation). The relative risk of low BMI group (RR = 1.01, 95% CI: 0.84 - 1.21) was not significant different and the relative risk of obesity significantly increased (RR = 1.36, 95% CI: 1.04 - 1.80) while the lowest relative risk was in normal BMI group. The relative risks increased for CVD death, but decreased for cancer death with increased levels of BMI and a "U" shaped relationship was found between BMI groups and mortality for other reasons, which remained after excluding the early death and smokers. CONCLUSION: BMI in normal level was not only related to low risk of all causes of death, but also with relative low risk of CVD, cancer and other deaths. Data were important to public health.

Adult↗

PubMed2002

Serial high-frequency ultrasound assessment of progressive changes in left ventricular structure and function in rats with chronic pressure overload.

OBJECTIVE: To determine the feasibility and accuracy of high-frequency ultrasound in evaluating the left ventricular (LV) structure and function in normal and pressure overload rats and to examine the changes of the left ventricle during its transition from hypertrophy to heart failure. METHODS: Thirty-eight female rats were randomly assigned to normal (n = 10), operated (n = 16) and sham-operated (n = 12) groups. Parasternal long axis and short axis images were acquired by a 7.5 mHz linear ultrasound probe at 12 weeks and 20 weeks after the operation respectively. RESULTS: Left ventricular structure and function could be satisfactorily imaged for dimensions and mass. Compared to the sham-operated groups, at 12 weeks after the operation, the operated rats had increased LV wall thickness and mass (P < 0.01) with normal cavity and FS% (P > 0.05). At 20 weeks after the operation, the LV wall thickness showed no further progressive change and the LV mass increased greatly with slightly dilated LV cavity and decreased FS% (P < 0.05). CONCLUSIONS: High-frequency echocardiography provides a useful means to noninvasively evaluate LV dimensions, mass and function in rats. It will have great value for evaluating LV remodeling during the transition from LV hypertrophy to heart failure, as well as the effects of intervening drugs.

Animals↗

PubMed2002

[Relative risk of death and life expectancy in low cardiovascular risk population].

OBJECTIVE: To assess the relationship between low cardiovascular disease (CVD) risk and the mortalities of coronary heart disease (CHD), stroke, cancer and all causes as well as life expectancy in Chinese population. METHODS: CVD risk factors were surveyed in 1982 approximately 1985 for 30 thousand male and female participants aged 35 approximately 59 from 10 Chinese population groups including 3 groups of factory workers, 6 groups of farmers and 1 group of fishermen according a uniform protocol with standardized methods. Follow-up was carried out up to 1999 approximately 2000 and the causes of death were all documented. Low cardiovascular risk was defined as: SBP/DBP < 120/80 mm Hg without anti-hypertensive medication 2 weeks before the baseline survey, serum total cholesterol < 5.17 mmol/L, BMI > 18.5 but < 24 kg/m(2) and no smoking at baseline survey. Mortality rates of CHD and stroke, cancer and all causes the participants with low CVD risk were compared with the rest of the cohort and difference in life expectancy was estimated. RESULTS: Out of the whole cohort of 30 560 participants, 24 900 with complete data were available for the present analysis. Among these, 4 542 participants (18.2%) were defined as low CVD risk group, including 959 (7.7%) men and 3 583 (28.9%) women. During a follow-up of 15.2 years on average, 243 deaths including 6 CHD, 15 stroke and 117 cancer deaths took place in low risk group, while 2 383 deaths including 182 CHD, 333 stroke, and 934 cancer deaths occurred in rest of the cohort. Cox proportional hazards model adjusted for age showed that the relative risks of death of CHD, stroke, cancer and all causes in low risk group were 0.51 (95% CI: 0.19 approximately 1.37), 0.30 (95% CI: 0.11 approximately 0.81), 0.86 (95% CI: 0.62 approximately 1.19) and 0.77 (95% CI: 0.62 approximately 0.96) for men and 0.11 (95% CI: 0.03 approximately 0.45), 0.31 (95% CI: 0.17 approximately 0.58), 0.84 (95% CI: 0.66 approximately 1.10) and 0.67 (95% CI: 0.56 approximately 0.79) for women, respectively. Life expectancy was 2.6 years longer for men and 4.0 years longer for women in the low risk group. CONCLUSION: The mortality rates of CVD and all causes were lower and life expectancy was longer in the participants with low CVD risk. Keeping low risk profile may not only prevent from having CVD but also extend life expectancy.

Adult↗

PubMed2002

Cartilage end-plate rupture of the lumbar vertebrae: report of 7 cases.

The authors report the clinical manifestations, imaging features, surgical approaches and the outcome of 7 cases of cartilage end-plate rupture of the lumber vertebrae, attempting to explore the pathogenesis and describe the clinical and pathological features of the disease. The diagnosis and treatment are also discussed in brief.

Adult↗

PubMed2002

Irradiation-induced apoptosis of mouse bone marrow stromal cells.

OBJECTIVE: To study the apoptotic patterns of bone marrow stromal cells (BMSCs) after irradiation. METHODS: Apoptosis of BMSCs induced by (60)Co gamma irradiation was detected by both flow cytometry and electron microscopy. RESULTS: Compared with normal control group, no manifest changes in the apoptosis ratio occurred in BMSCs after 50 Gy irradiation (P>0.05) as demonstrated by flow cytometry. Four hours after 100 Gy irradiation, manifest changes in apoptosis ratio of BMSCs were observed (P<0.01), reaching the peak 20 h later. Similar apoptotic patterns occurred in BMSCs exposed to irradiation of 200 Gy (P>0.05), only the apoptosis ratio was slightly higher. CONCLUSION: Irradiation of proper dose may induce apoptosis in vitro in BMSCs that possess strong resistance to irradiation.

Animals↗

PubMed2002

Reconstruction and transplantation of composite skin containing keratinocytes and fibroblasts.

OBJECTIVE: To investigate the role of fibroblasts in reconstruction of composite skin, and evaluate the effect of composite skin on full-thickness skin defect. METHODS: Keratinocytes and fibroblasts were seeded on the surface of acellular dermal matrix and cultivated in vitro to reconstruct the composite skin. Adherence of keratinocytes to dermal matrix was observed. Then take rate and histological construction were investigated after the composite skin was used to cover full-thickness skin defect wound in nude mice (n = 16). RESULTS: Keratinocytes grew and proliferated to reach tho confluence on the surface of the acellular dermal matrix. Keratinocytes adhered more stablely and could not be torn down from dermal matrix in operation when few fibroblasts were seeded on the epidermal surface of the dermal matrix. After grafting, the composite skin closed the full-thickness wound in nude mouse. The total survival was achived in 10 mice (62.5%). The newly generated skin was with intact histological construction of base membrance containing laminin and type IV collagen. CONCLUSION: Composite skin could close the full-thickness wound, and fibroblasts could improve adherence of keratinocytes to dermal matrix, which should benefit the survival of composite skin.

Animals↗

PubMed2002

[Effects of exposure to aluminum on some metal elements contents in hippocampus of rat].

OBJECTIVE: To investigate the effects of exposure to aluminum (Al) on Zn, Fe, Cu and Ca contents in hippocampus of rats. METHODS: AlCl(3).6H(2)O was administered orally through diet (8% of body weight) to SD rats at doses of 0 (A), 11.2 (B), 55.9 (C), 111.9 (D) mg Al(3+)/kg BW for successive 90 days. Then Al, Zn, Fe, Cu and Ca contents in hippocampi of rats were determined by atomic absorption spectrophotometry. RESULTS: After oral exposure to Al, the Al content in hippocampus of rat increased significantly with a remarkable dose-effect relationship (r = 0.731, P < 0.001), The Zn, Fe, Ca and Cu contents in these four groups are as follows: Group A (18.29 +/- 2.48, 24.86 +/- 1.97, 48.69 +/- 22.08, 4.53 +/- 0.99) mg/g, Group B (17.22 +/- 2.06, 27.54 +/- 2.87, 42.79 +/- 14.42, 4.06 +/- 0.41) mg/g, Group C (14.46 +/- 1.90, 20.18 +/- 2.79, 29.95 +/- 7.33, 3.98 +/- 0.25) mg/g, Group D (15.85 +/- 2.54, 20.96 +/- 2.83, 36.14 +/- 12.66, 4.53 +/- 0.58) mg/g. Compared with the control group A, the Zn and Fe contents in group B and group C decreased significantly (P < 0.05), and the Ca content in group C also decreased significantly. CONCLUSION: Oral exposure to Al may result in accumulation of Al in hippocampus of brain and thus affect some essential elements (Zn, Fe, Cu and Ca) contents in the hippocampus at different degrees.

Aluminum↗

PubMed2002

[Cytokeratin expression in the epithelial cells of nasal polyp].

OBJECTIVE: To study the expression of cytokeratin in epithelial cells of nasal polyp and its significance. METHOD: The monoclonal antibody of AE1, AE3, CK7, CK14, CK19, CK20 were used to determined the corresponding cytokeratin expression in epithelial cells of nasal polyp with immunohistochemical staining. RESULT: 1. AE1, CK7, CK19 staining were positive in various pathological epithelium of nasal polyp. AE1, CK19 showed positive in total layer of epithelium. CK7 was positive in goblet cells and basal cells of the pseudostratified epithelium. 2. AE3, CK20 staining were positive in part of simple epithelium and stratified epithelium. 3. AE1, AE3, CK7, CK19 staining showed focal positive in transitional epithelium. CONCLUSION: CK7, CK19 are the one of the essential assembly type of cytokeratin in epithelium of nasal polyp. During the process of inflammatory reaction, the expression of partial cytokeratin subtype would lose while a new cytokeratin pattern would appear.

Epithelial Cells↗

PubMed2002

Severe hepatic trauma: surgical strategies.

OBJECTIVE: To probe into effective surgical procedures and improve the outcome of treatment for patients with severe hepatic injury. METHODS: A retrospective study involving 113 patients with severe hepatic trauma (AAST grade IV and V) during the past 12 years was carried out. Ninety-eight patients underwent surgical treatment. Surgical interventions including hepatectomy or direct control of bleeding vessels by finger fracture technique with Pringle maneuver, selective ligation of hepatic artery, retrohepatic caval repair with total hepatic vascular occlusion, and perihepatic packing were mainly used. RESULTS: In the 98 patients treated operatively, the survival rate was 69.4% (68/98). Among 40 patients with juxtahepatic venous injury (JHVI), 15 were cured with the maximum blood transfusion of 12,000 ml. Eight cases of Grade IV injury treated nonoperatively were cured. The percentage of failure of nonoperative management was 42.9% (6/14). The overall mortality rate was 32.7% (37/113), and 57% of the deaths were due to exsanguination. CONCLUSIONS: Reasonable surgical procedures based on classification of hepatic injuries can increase the survival rate of severe liver trauma. Accurate perihepatic packing is effective in dealing with JHVI.

Adolescent↗

PubMed2002

[Effects of fenvalerate on reproductive and endocrine systems of male rats].

OBJECTIVES: To evaluate the impairment of fenvalerate on reproductive and endocrine systems and clarify the mechanism of action. METHODS: Different doses of fenvalerate (0, 2, 4, 12, 60 mg/kg) were orally treated to the adult male SD rats for 15 days and 30 days, respectively. The levels of serum follicle stimulating hormone(FSH), luteinizing hormone (LH), testosterone(T) and testis homogenate T were determined by radioimmunoassay(RIA). Besides, the activity of testicular marked enzymes such as acid phosphatases(ACP) and gamma-glutamyl transpeptidase(gamma-GT) were examined, and sperm head counts were measured to explain the changes of daily sperm production(Spr). RESULTS: In fifteen days, serum FSH levels markedly increased in rats exposed to fenvalerate of < or = 12 mg/kg groups(P < 0.01) and serum levels of LH increased in 12 mg/kg group(P < 0.01). In addition, T levels in testis homogenates decreased after treated with the doses of > or = 12 mg/kg groups compared with the control group(P < 0.01). In thirty days, serum contents of FSH were significantly elevated in the doses of > or = 12 mg/kg groups(P < 0.01) and homogenate levels of T were diminished in the low dose group(2.4 mg/kg) (P < 0.05). Activity of ACP increased in 12 mg/kg group after fifteen days(P < 0.05) and was restrained in the high dose group(60 mg/kg) in thirty days(P < 0.05), but the contents of gamma-GT were arrested with different doses dependently in the testis(P < 0.05). Fenvalerate caused dose-dependent reduction in sperm head counts and daily sperm production, which markedly reduced at the doses of > or = 12 mg/kg groups(P < 0.01). CONCLUSIONS: Fenvalerate has obvious reproductive toxicity on male rats and can change their serum and testis homogenate levels of sex hormone or activity of testicular marked enzymes, which may be correlated with the impairment of Sertoli cell and spermatogenic epithelium.

Animals↗

PubMed2002

[MnSOD gene regulated by aminopeptidase N promoter specifically protects bone marrow from radiation].

BACKGROUND & OBJECTIVE: It is an effective way to induce radio-tolerant gene into hematopoietic cells in bone marrow for overcoming the suppression of radiotherapy on hematopoietic system. However, this also increases the radiation tolerance of tumor cells. This study was designed to investigate a method to specifically protect bone marrow cell from being damaged by radiation, along without increasing resistance of tumor cell to radiation. METHODS: The retrovirus vector of manganese superoxide dismutase (MnSOD) gene regulated by aminopeptidase N (APN) bone marrow-specific gene promoter was constructed and induced into myeloblastic KG1a and cancer cell BEL7402. MnSOD mRNA level was analyzed by PT-PCR; MnSOD activity in the cells was determined; the sensitivity of bone marrow cell and hepatic carcinoma cell to x-ray was detected by cell survival test; the cell apoptosis was analyzed with flow cytometry and fractural DNA electrophoresis. RESULTS: The MnSOD mRNA level and enzyme activity in KG1a cells transferred with the gene was obviously increased. Expression of MnSOD mRNA drove by APN myelo-specific promoter effectively inhibited apoptosis of KG1a cells induced by radiation and endowed KG1a cell line with the enhancement of tolerance to radiation, which increased by 3.7 folds compared to parental cells at the dose of 10 Gy. In contrast, the level of MnSOD mRNA, the enyme activity of MnSOD and the radiosensitivity had no significant change in BEL 7402 cells transduced with MnSOD gene. CONCLUSION: APN bone marrow-specific promoter could control MnSOD gene expression highly in myeloid cell and lower in cancer cell. In the process of killing of cancer cell by x-ray, MnSOD gene regulated by APN bone marrow-specific promoter could specifically protect myeloid cell. This study provides a new clue to solve the bone marrow suppression in high dose radiotherapy.

3T3 Cells↗

PubMed2002

[An experimental study on the dermal substitute of spongy collagen membrane].

OBJECTIVE: To investigate the practicability of a spongy collagen membrane as a dermal substitute. METHODS: Porcine skin collagen was harvested and mixed and precipitated with chondroitin-6-sulfate, and then lyophilized for 48 hours to form sheets of highly porous membrane. The collagen membrane was embedded subcutaneously in SD rat's skin. The histological compatibility, the vascularization degree and degradation status were determined periodically by means of tissue sampling. RESULTS: The collagen membrane possessed some degree of strength and tenacity with a structure consisting of multidinous interconnecting pores. It was easy to manipulate. Experimental subcutaneous embedding in SD rats indicated that the membrane exhibited good tissue compatibility, strong tendency to vascularization, with no evidence of acute inflammatory reaction, and slow degradation rate. CONCLUSION: Spongy collagen membrane might be an optimal dermal substitute for wound coverage.

Animals↗

PubMed2002

[Application of fingerprint chromatogram in quality control of Shen-Mai injection].

The theory and practice of traditional Chinese medicine require some comprehensive methods to assess quality of the Chinese herbal medication. Fingerprint chromatogram is one of the feasible approaches to evaluate the quality of Chinese herbal medication. So the fingerprint chromatogram of Shen-Mai injection was established by using reversed-phase high performance liquid chromatography. The chromatographic conditions were as follows: a Hypersil C18 column was used; the mobile phase was composed of water (A) and acetontrile (B) with linear gradient elution (0-50 min, 5%-95% B, volume fraction); the flow rate was 1.0 mL/min and the UV absorbance detection was set at 202 nm. The peak-area ratios of twenty-three fingerprint peaks and internal standard (diphenyl) were taken as the criteria for quality control. The quality differences in various batches and various manufacturers of Shen-Mai injections were investigated by projection discriminance based on principal component analysis. The results show the method developed is convenient, reliable and applicable for the quality control analysis of Shen-Mai injection.

Chromatography, High Pressure Liquid↗

PubMed2002

[Theoretical calculation and experimental study of membrane thickness of alginate-(poly-L-lysine)-alginate microcapsules].

Alginate-(Poly-L-Lysine)-Alginate(APA) microcapsules were prepared by Electrostatic Droplet Generator(EDG) technique and the thickness of microcapsule membrane, which was composed by polyelectrolyte complex, were studied in this paper. The theoretical formula was given for the measurement of membrane thickness of APA microcapsules by element analysis of membrane and calculation. The membrane thickness was 7-10 microns by theoretical calculation. On the other hand, the thickness of membrane was measured by SEM and optical microscopy and the results were 7 microns and 12 microns, respectively. The results showed that theoretical calculation is in good accordance with experimental determoination of mermbrane thickness and the membrane thickness of APA microcapsule is about 7-10 microns. The optical microscopy is an easy way to measure membrane thickness.

Alginates↗