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Biomedical subjects

J Cheng

Publications and source records attributed to J Cheng.

At least 271 records · Page 15Linked to original sources
PubMed1998

[The effect of a vaccine made from 39kd hydrophobic outer membrane protein of Leptospira interrogans on neurohumoral and red cell immunity function of the guinea pigs].

A randomized control trial was conducted to determine the immunoprotective efficacy of OmpL39. 36 guinea pigs were divided into OmpL39 group, whole leptospiral cell vaccine (WLCV) group, other proteins of Leptospira group, and negative control group (normal saline, NS). The results showed that all the guinea pigs of infected OmpL39 and WLCV still survived, but all the control guinea pigs died. Immunoprotective efficacy was 100% for OmpL39 and WLCV. OmpL39 levels were similar to WLCV levels and higher than controls (P < 0.05). These suggested that OmpL39 could be used as important immunoprotective antigen to develop the genetic vaccine of the targeting delivery system. Also it was observed that OmpL39 could produce 100% immunoprotective efficacy, have higher MAT level (> 1:3200) and regulate 5-HT, 5-HIAA, DA, NE. The 5-HT, DA, NE concentration was lower and 5-HIAA was higher than that of controls after stimulating the guinea pigs with OmpL39 (P < 0.05). The results suggested that OmpL39 genetic vaccine could produce immunity function and have an active effect on absorbing inflammation and protecting organs and tissues. Besides, the red cell immunity efficacy of the guinea pigs was changed during immunity response and the RBC-C3b RR and the RBC-ICR were increased. The RFER was increased; the RFIR was decreased. RFER/RFIR was remarkably higher than that of control (P < 0.05). These suggested that OmpL39 could increase red cell immunity function.

Animals↗
PubMed1998

The effects of increased gravity and microgravity on cardiac morphology.

BACKGROUND: Our previous study of rats exposed for 14 d to microgravity on Cosmos 2044 revealed morphological changes consistent with cardiac atrophy. METHODS: In the current comparison study, light and electron microscopic studies were performed on cardiac muscle from 10 rats exposed to hypergravity (continuous centrifugation at 2G) for 14 d. RESULTS: Myofiber area was significantly greater in the 2G papillary muscle as compared with muscle from 10 control rats of the same strain and size. This contrasts with the significant decrease in myofiber area previously seen in the rats exposed to microgravity. At the electron microscopic level, general morphological features were similar in both groups and resembled tissue from control rats from the previous Cosmos studies. However, mitochondria from papillary and ventricular muscle from the 2G rats revealed signs of fatigue typical of the early stage of hypertrophy. These results are consistent with a state of adaptive cardiac hypertrophy for the 2G group.

Adaptation, Physiological↗
PubMed1998

[Correlation study of spontaneous apoptosis, PCNA, and p53 in esophageal squamous-cell carcinoma].

OBJECTIVE: To investigate the inter-relationships among spontaneous apoptosis, proliferative activity and p53 mutation in esophageal squamous-cell carcinoma. METHODS: In 30 previondy untreated patients with esophageal squamous-cell carcinoma, tissues were examined for apoptosis by in-situ TUNEL, PCNA by immunohistochemistry, p53 mutation by PCR-SSCP and immunohistochemistry. The number of apoptotic cells per 10 low-power microseopic fields was taken as the apoptotic index. RESULTS: Apoptotic index of cells with high proliferative activity was significantly higher than that of cells with low proliferative activity (P < 0.05). In tumors with p53 gene mutation, apoptotic index of cells with high proliferative activity and low proliferative activity was significantly different (P < 0.05). No significant differences were observed in apoptotic index in tumors positive and negative for p53 mutation as examined by PCR-SSCP or immunohistochemistry (P > 0.05). CONCLUSION: In squamous-cell carcinoma of the esophagus, cells with high proliferative activity are apt to undergo spontaneous apoptosis.

Apoptosis↗
PubMed1998

[Mismatched PCR combined with restriction fragment length polymorphism assay for identification of hot spot for mutation in core promoter sequence of hepatitis B virus in Chinese isolates].

OBJECTIVES: To investigate the prevalence of the core promoter variant in Chinese HBV carriers and to explore the clinical and epidemiological problems of the variant. METHODS: A novel method for detecting the double mutation in core promoter was developed. By using an antisense primer that starts at nt 1765 and bears a mismatch at nt 1767, we introduced an artificially created Bcl I cleavage site if the double mutation was present. The prevalence and clinical significance of mutation in the core promoter were investigated in 114 Chinese individuals infected with HBV. RESULTS: Serum samples from 37 asymptomatic carriers and patients harbored core promoter mutant, some with precore mutation. The prevalence was higher in carriers and patients without HBeAg than those with HBeAg. The results in the PCR-RFLP assay perfectly agreed with the data from direct sequencing. CONCLUSION: The presumed core promoter mutations resulting in decreased HBeAg synthesis might be one of the factors leading to persistence of HBV infection and active liver disease.

Adult↗
PubMed1998

[The factors of cholesteatoma remnants].

In this study, 619 patients underwent radical mastoidectomy from 1985 to 1996 were followed up. There are 48 cases with cholesteatoma remnants, of which, 31 cases in middle tympanic cavity, 14 cases in superior tympaine cavity, 3 cases in mastoid process. The rate of recurrence was higher in adults than in children. It has been suggested that age, character of cholesteatoma, operation and, the fissure existing in mastoid process play a role in recurrence of cholesteatoma after radical mastoidectomy in chronic otitis medica.

Adolescent↗
PubMed1998

[Quantitative determination of extracellular glutathione and cysteine in gerbil brain by microdialysis and high performance liquid chromatography with electrochemical detection].

A method for the determination of glutathione and cysteine in microdialysate by HPLC with electrochemical detector has been described. The column used was Hypersil ODS, 5 microns, 200 mm x 4.6 mm i.d. and mobile phase was 50% 0.2 mol/L KCl, 10.6% 0.2 mol/L HCl, 39.4% methanol and 0.1 mmol/L EDTA (pH 2.0) with a flow rate of 1 mL/min. The microdialysis probe (membrane: pc, length: 10 mm, diameter: 0.5 mm/CMA) was inserted into the right striatum of gerbil at the following coordinates: 1.5 mm anterior and 1.5 mm lateral to bregma, and 3.5 mm below dura. Electrochemical pretreatment of a glassy carbon electrode used as a working electrode in an electrochemical detector has been found to enhance the analytical capability of detector for the determination of glutathione and cysteine. The quantitative determination was made with an electrochemical detector at 0.9 V and by external standard method. The method gave good recoveries and reproducibilities. The average recoveries of two analytes were 91.4% and 87.3% respectively. Extracellular fluid glutathione and cysteine concentrations in the striatum of gerbil brain were determined by the microdialysis and chromatography described in this study. The contents of Cys and GSH in microdialysate of gerbil striatum were 65.54 +/- 12.96 nmol/L and 68.59 +/- 13.23 nmol/L. The results were comparable with those reported in previous works.

Animals↗
PubMed1998

[Research and application of far-infrared rays to drying Chinese medicinal herbs in small pieces].

OBJECTIVE: To introduce a far-infrared ray dryings device. METHOD: The research background, work tenets, structure, function, technical parameters and tentative application of the device were reported. Chinese medicinal herbs in small pieces which contain volatile oils were dried by far-infrared rays and airing. The two drying methods were compared. RESULT AND CONCLUSION: Not degrading the quality of medicinal herbs in small pieces, the device can be used to dry various kinds of medicinal herb pieces and thus deserves popularization.

Infrared Rays↗
PubMed1998

[A preliminary investigation on causes of failure of vitreoretinal surgery for complicated rhegmatogenic retinal detachments].

OBJECTIVE: To evaluate the failure causes of vitreoretinal surgery for complicated rhegmatogenic retinal detachment. METHODS: Vitreoretinal (VR) surgery was performed on 477 cases (479 eyes) with complicated rhegmatogenic retinal detachment, the operative procedures including vitrectomy, peeling of pre-retinal membrane, fluid-air exchange, inert gas (SF(6) or C(3)F(8)) or silicone tamponade. RESULTS: On discharge, the operation was effective in 349 eyes (72.87%) and failed in 130 (27.13%) eyes. CONCLUSION: The multiple stepwise multivariate regression shows that the factors significantly influencing VR surgery are silicone tamponade, giant retinal tears, SF(6) tamponade, iatrogenic tear, anterior proliferative vitreoretinopathy (PVR), subretinal proliferation, PVR, C(3)F(8) tamponade, operative frequency and choroidal detachments.

Adolescent↗
PubMed1998

[Instantaneous power maxima and power spectrum maxima analysis of second heart sounds signals].

We employed the time-frequency analysis to the processing of the second heart sound signals and studied the time-frequency spectrum of the normal and abnormal second heart sound. According to the time marginal and frequency marginal, we made the instantaneous power maxima and power spectrum maxima of the second heart sounds, which were thought as the quantity index about physiology and pathology. The results showed that the time-frequency spectrum of the second heart sounds gave a whole comprehensive description to dynamic course of the signals. The instantaneous power maxima and power spectrum maxima contain the time varying information in the second heart sound.

Heart Sounds↗
PubMed1998

[Time-varying spectral analysis of cardiac murmurs].

In this paper, the cardiac murmurs (systolic murmurs, diastolic murmurs and machining murmurs) are classified by hemodynamics and studied by time-frequency analysis. We get the time-varying spectrum of the signals. The results, which are from the different kinds of murmurs in 28 patients with heart disease, show that the time-varying spectrum based on cone-shaped kernel distribution are capable to correctly represent the power density and dynamic course of the series in time-frequency domain. The method has high time-frequency resolution, and the time-varying spectrum of each murmur has its characteristics.

Electrophysiology↗
PubMed1998

[Segmentation of osteomas X-ray image using mathematical morphology].

In this paper, we introduce a method for the segmentation of osteomas X-ray images. This method is mainly based on mathematical morphology. Structuring elements are selected according to the shape of osteomas. After gray scale morphology operations, osteomas boundary is extracted by histogram threshold. Further processing of resulting boundary with binary morphological operation produces a closed osteomas contour. So osteomas is isolated from background.

Bone Neoplasms↗
PubMed1998

[Application of time-frequency filter of wavelet to single-trail ERP extracting].

A new approach to extracting single-trail event-related potential(ERP) in combination with the correlation analysis has been proposed. This approach, called time-frequency filter, is based on the concept that multiresolution wavelet transforms. At first, an investigation of the properties in time and frequency domain was carried out on the ERP. On the basis of the findings, the time-frequency filter of wavelet was designed and used for single-trail ERP extracting. The results and related discussion are presented in this paper.

Adult↗
PubMed1998

[The time-frequency analysis of the heart sound].

The Wigner-Ville distribution, the Choi-Williams distribution, and cone-kernel distribution are three time-frequency distributions. We compared the interference attenuation and time-frequency concentration properties of the three TFDs. The properties were then further investigated by studying the results obtained for a chirp signal. We analysed the heart sounds, nonstationary signals, with the three TFDs. The results indicate that the time-frequency signal analysis methods have high time-frequency resolution. The time-frequency signal analysis techniques may be helpful in unveiling the complex mechanisms of heart sound generation and be used in medical research and clinical diagnosis.

Adult↗
PubMed1998

[Surface treatments for dental titanium castings].

Because pure titanium is highly reactive at high temperature, its casting surface is easily coated with a thick contaminated layer that affects its physical and chemical properties, and consequently a stable superficial oxide membrane develops in the presence of air or water even at room temperature, which makes the surface discolored. Therefore, surface treatments for pure titanium castings are more important than those for other dental alloy castings. This article reviews the methods of surface treatments for dental titanium castings in four aspects: physical finishing, chemical finishing, electro-chemical finishing and surface modification technology.

Dental Casting Investment↗
PubMed1998

[The use of isoparametric element of arbitrary hexahedron for solving 3-D thoracic potential distribution].

Isoparametric element of arbitrary hexahedron plays an important role in finite element analysis. This article devotes itself to establishment of mathematical model and combination of derivative of shape function of such element type. In addition, the article also discusses the usage of isoparametric element for solving 3-D thoracic potential distribution in electrical field.

Algorithms↗
PubMed1998

Molecular characterization of the creatine kinases and some historical perspectives.

Over the last 15 years, molecular characterization of the creatine kinase (CK) gene family has paralleled the molecular revolution of understanding gene structure, function, and regulation. In this review, we present a summary of advances in molecular analysis of the CK gene family with a few vignettes of historical interest. We describe how the muscle CK gene provided an essential model system to examine myogenic regulatory mechanisms, leading to the discovery of the binding site for the MyoD family of basic helix-loop-helix transcription factors essential in skeletal myogenesis and the characterization of the MEF2 family of factors with an A/T rich consensus binding site essential in skeletal myogenesis and cardiogenesis. Cloning and characterization of the four mRNAs and nuclear genes encoding the cytosolic CKs, muscle and brain CKs, and the mitochondrial (Mt) CKs, sarcomeric MtCK and ubiquitous MtCK, has allowed intriguing study of tissue-specific and cell-specific expression of the different CKs and analysis of structural, functional, regulatory, and evolutionary relationships among both the four CK proteins and genes. Current and future studies focus on understanding both cellular energetics facilitated by the CK enzymes, especially energy channelling from the site of production, the mitochondrial matrix and inner membrane, to various cytosolic foci of utilization, and regulation of MtCK gene expression at the cell and tissue-specific level as models of regulation of energy producing genes.

Amino Acid Sequence↗
PubMed1997

Vesnarinone prolongs action potential duration without reverse frequency dependence in rabbit ventricular muscle by blocking the delayed rectifier K+ current.

BACKGROUND: Methanesulfonanilide derivatives, selective inhibitors of the rapidly activating component (I(Kr)) of the delayed rectifier potassium current (I(K)), prolong action potential duration (APD) of cardiac muscles with reverse frequency dependence, which limits their clinical use because of proarrhythmia. Vesnarinone, a quinolinone derivative developed as a cardiotonic agent, has complex pharmacological properties, but its clinical efficacy is explained in part by I(K) reduction. Therefore, we investigated the mode of I(K) block by vesnarinone. METHODS AND RESULTS: I(K) of the rabbit ventricular myocyte was activated by voltage-clamp steps applied from a holding potential to various depolarizing levels. The development of I(K) block at depolarization (+10 mV) and its recovery process at hyperpolarization (-75 mV) were compared between vesnarinone and E-4031. The I(K) block by vesnarinone (3 micromol/L) developed and recovered monoexponentially, with time constants of 361 ms (n=5) and 1.87 seconds (n=4), respectively. I(K) block by E-4031 (0.3 micromol/L) developed instantaneously, with no recovery from the block at hyperpolarization. The I(K) block by vesnarinone, estimated by I(K) tail after a train of depolarizing pulses (for 30 seconds at 0.2 to 2 Hz), was increased with increasing frequency (twofold at 2 from 0.2 Hz), but that by E-4031 was unchanged. In rabbit papillary muscles, vesnarinone (10 micromol/L) prolonged APD at stimulation frequencies >0.2 Hz, whereas E-4031 (0.3 micromol/L) prolonged that in a reverse frequency-dependent manner. CONCLUSIONS: Vesnarinone may prolong the repolarization of human cardiac muscle without reverse frequency dependence, because I(Kr) is expressed in humans as well as in the rabbit. Thus, this drug may be a model for an ideal class III drug without the risk of proarrhythmia.

Action Potentials↗