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Biomedical subjects

Q Xue

Publications and source records attributed to Q Xue.

87 records · Page 5Linked to original sources
PubMed1994

Variability of intracellular lactate dehydrogenase isoenzymes in single human erythrocytes.

Trace amounts of enzymes within single human erythrocytes can be quantified by a combination of on-column reaction and capillary electrophoresis. A detection limit of 1.3 x 10(-21) mol of LDH was achieved with laser-induced fluorescence by monitoring the product of the enzyme-catalyzed reaction between lactate and NAD+. Single erythrocyte analysis clearly isolates the major forms of LDH. The variation of total LDH activity in a population of cells from a single individual is large, but the relative activities of the isoenzymes LDH-1 and LDH-2 are fairly constant. This can be explained by the distribution of cell age in the population. A lower enzyme activity is indicative of senescence. The efficient separation of different LDH forms and the high detection sensitivity opens up the possibility of multiple-enzyme assays with a single mammalian cell.

Electrophoresis↗
PubMed1994

Indirect fluorescence determination of lactate and pyruvate in single erythrocytes by capillary electrophoresis.

A scheme of using fluorescein as the fluorophore for indirect detection of anions was demonstrated. This system is quite stable at a fluorescein concentration of 100 microM even without any other buffer components. Different injection modes affect the limit of detection (LOD). A LOD of about 20 amol was obtained for lactate under optimal conditions. Lactate and pyruvate in the intracellular fluid of erythrocytes were measured in this manner. The average amounts in a single erythrocyte for lactate and pyruvate are 1.3 and 2.1 fmol, respectively, or a ratio of 1.6 for pyruvate to lactate. Variations of the absolute amounts and the ratios are fairly large among a group of 27 cells examined. This is consistent with the difference of cells in size and composition. Although the migration times changed by up to 20% during a series of runs from the influence of concomitants in the cells, the migration time ratio was maintained around 1.072 with 3% relative standard deviation.

Adult↗
PubMed1993

Hemodynamic and nonhemodynamic mechanism of experimental pulmonary edema in rats and the effect of anisodamine and tetramethylpyrazine--electron microscopic observation and measurement of pulmonary arterial, pulmonary arterial wedge and systemic arterial pressure (Part 2).

The pulmonary edema (PE) induced by adrenaline (AD) administration is similar to neurogenic PE. Anisodamine (ADM, 654-2, 30 mg/kg) and tetramethylpyrazine (TMP, 120 mg/kg) have shown significant preventive effects. Electron microscopic observation was carried out to study the changes of microvascular permeability, and the dynamic change of mean pulmonary arterial pressure (PAP, 40 rats), mean pulmonary arterial wedge pressure (PAWP, 20 rats) and mean carotid arterial pressure (CAP) were also measured. The results suggested that both ADM and TMP have significant inhibitory effects on PAWP and CAP increase, as well as on the damage responsible for the increase of microvascular and alveolar permeability.

Adrenergic alpha-Agonists↗
PubMed1993

Hemodynamic and nonhemodynamic mechanisms of experimental pulmonary edema in rats and the effects of anisodamine and tetramethylpyrazine--estimation of blood gas analysis, RBC superoxide dismutase and prostaglandin E2 in plasma and bronchoalveolar lavage (Part 3).

Anisodamine (ADM, 654-2, 30 mg/kg) and tetramethylpyrazine (TMP, 120 mg/kg) have shown an apparent preventive effect on pulmonary edema (PE). In this study, the nonhemodynamic mechanism was studied: The dynamic changes of PaO2, O2Sat, PaCO2, and blood pH were measured, and RBC superoxide dismutase (SOD) and plasma and bronchoalveolar lavage (BAL) PGE2 levels were estimated. It was concluded that ADM and TMP exerted inhibitory effects on the hypoxic state. The ability of ADM and TMP to adjust RBC SOD and PGE2 levels may be one of the preventive mechanisms of the drugs.

Animals↗
PubMed1993

Hemodynamic and nonhemodynamic mechanisms of experimental pulmonary edema in rats and the effect of anisodamine and tetramethylpyrazine. Part 1: Survival rate, pulmonary index, pathological change and pulmonary vascular permeability.

Pulmonary edema (PE) which is similar to the neurogenic type was induced by adrenaline (AD) administration (0.1 mg/kg) in rats. Acute progressive respiratory distress, cyanosis and dyspnea occurred. All the experimental animals in the PE group died within 20 min after AD injection, with a pulmonary index (PI) of 1.70 +/- 0.47 (mean +/- S) which was much higher than that in the normal group. The mortality rate was 100%. It was found that in rats with PE, a protein-rich fluid filled the alveolar and interstitial spaces, and ecchymosis occurred. The capillary permeability as estimated by Evans blue injection showed that Evans blue from extraction fluid and bronchoalveolar lavage (BAL) in the PE rats was at a much higher level than that in the normal control (NC) rats. In anisodamine (ADM, 654-2) and tetramethylpyrazine (TMP) treated rats, almost all the damage was diminished or absent, and the mortality rates were decreased from 100% to 4.4% and 20%, respectively. 654-2 and TMP could significantly inhibit the increase of pulmonary permeability.

Animals↗
PubMed1992

Neural-network-based adaptive matched filtering for QRS detection.

We have developed an adaptive matched filtering algorithm based upon an artificial neural network (ANN) for QRS detection. We use an ANN adaptive whitening filter to model the lower frequencies of the ECG which are inherently nonlinear and nonstationary. The residual signal which contains mostly higher frequency QRS complex energy is then passed through a linear matched filter to detect the location of the QRS complex. We developed an algorithm to adaptively update the matched filter template from the detected QRS complex in the ECG signal itself so that the template can be customized to an individual subject. This ANN whitening filter is very effective at removing the time-varying, nonlinear noise characteristic of ECG signals. Using this novel approach, the detection rate for a very noisy patient record in the MIT/BIH arrhythmia database is 99.5%, which compares favorably to the 97.5% obtained using a linear adaptive whitening filter and the 96.5% achieved with a bandpass filtering method.

Algorithms↗
PubMed1992

[Age-related morphological changes in the suprachiasmatic nucleus of the rat hypothalamus].

A comparative ultrastructural investigation of the hypothalamic suprachiasmatic nuclei (SCN) of young, adult and senescent SD male rats was carried out. The neurons and neuroglial cells in SCN of the senile rats displayed more lipofuscin (Lipo) accumulation in comparison with those of the younger animals. Golgi apparatus (Gol) of the three age groups converted from well-ordered cisternae to irregular ones with extensive dilatation and vacuolization. More neuroglial cells with broader somatic membrane appositional to that of neuron participated in satellitosis in the senile age group. Some unusual structures such as special arrangements of the rough endoplasmic reticula and multilamellar neuroglial envelope (Mge) wrapping neurite were encountered in the perikarya of some neurons or SCN neuropile respectively.

Age Factors↗
PubMed1992

[Age-related change of synaptic number in the suprachiasmatic nucleus of the rat hypothalamus].

Numerical changes of the synapses in the hypothalamic suprachiasmatic nuclei (SCN) of rats at different ages were investigated with electron microscope, The population of the major SCN synapses formed with dendrite and total number of synapses were found to be reduced with advancing age. Compared with the young animal group, the synaptic number was statistically different from that in the adult or senescent group. As a result of these changes, the function of SCN might decline with aging.

Age Factors↗
PubMed1991

Effect of hypoxia on the pulmonary beta and alpha 1 adrenoceptors in rats.

The present study was designed to investigate the effect of hypoxia on the pulmonary adrenoceptors in rats. The density and distribution of pulmonary adrenoceptors were studied by using radioligand binding techniques and autoradiography. The beta adrenoceptors in lung homogenates were found to decrease by 24 h of hypoxia, and to unexpectedly increase at 1 week of hypoxia. Exposure to hypoxia for 2 and 4 weeks led to another decrease in beta adrenoceptors. In contrast, the alpha 1 adrenoceptors were increased markedly at 24 h and 4 weeks of hypoxia. A somewhat higher density of alpha 1 adrenoceptors was also found at 1 week and 7 weeks of hypoxia. The affinity of beta and alpha 1 adrenoceptors did not change. Using a computer image analysis system, beta adrenoceptors were found to be present in higher density in bronchioles than in pulmonary blood vessels before and during hypoxia, while the reverse was true of alpha 1 adrenoceptors. Both beta and alpha 1 adrenoceptors were found in high densities in the parenchyma.

Animals↗
PubMedDate not supplied

A compound sensor for biomechanical analyses of buttock soft tissue in vivo.

A sensor for in vivo biomechanical characterization of buttock soft tissue has been developed and evaluated. The sensor measures interface pressure, applied force, tilt, and rotation angle of the sensor head, and the thicknesses of multiple soft tissue layers. A composite ultrasonic transducer using a 1-3 ceramic-polymer structure was developed for the sensor. The sensor can identify subcutaneous soft tissue interfaces 5 to 65 mm below the skin surface with a 0.26-mm axial resolution, pressure over the range of 0 to 68 kPa, and force over the range of 0 to 3.6 kg. Our purpose for developing the sensor was to study the biomechanical characteristics of buttock soft tissues. Successful identification of distinguishing characteristics in persons with a susceptibility to pressure ulcers may result in the development of a risk assessment tool based on tissue characterization.

Biomechanical Phenomena↗
PubMedDate not supplied

Effects of matrix metalloproteinase inhibitor BB-94 on liver cancer growth and metastasis in a patient-like orthotopic model LCI-D20.

BACKGROUND/AIMS: The aim of this study was to try to understand the effects of the synthetic matrix metalloproteinase inhibitor Batimastat (BB-94) on hepatocellular carcinoma (HCC). METHODOLOGY: An orthotopic metastatic human hepatocellular carcinoma in nude mice model (LCI-D20) was used to study primary tumor growth, local invasion and metastasis of HCC. MTT assay was used to study the effects of BB-94 on cytotoxin and proliferation of HCC cell line SMMC-7721 in vitro. A gelatine zymograph was used to study the expression of MMPs in the LCI-D20 tumor tissue. RESULTS: BB-94 can inhibit primary tumor growth, local invasion, intrahepatic and lung metastasis, as well as prolong survival. BB-94 did not affect the proliferation of HCC cells in vitro. LCI-D20 tumor tissue expresses MMP-2 and MMP-9. CONCLUSIONS: BB-94 has a cytostatic therapeutic effect on HCC.

Animals↗