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Biomedical subjects

M Zeng

Publications and source records attributed to M Zeng.

At least 55 records · Page 3Linked to original sources
PubMed1999

[The study of oxygen-conserving nasal cannula and evaluation of it's oxygen saving ratio in treatment].

OBJECTIVE: To study the oxygen-conserving nasal cannula(CNC), and to evaluate it's oxygen saving benefit ratio in COPD patients. METHODS: (1) CNC was designed as a device which conserved oxygen during exhalation and given oxygen during inhalation; (2) Evaluation of the effect of oxygen therapy: blood analysis was measured at different flows of oxygen (0.5, 1.0, 1.5, 2.0 L/min) before and after oxygen therapy. The test is randomized; Oxygen saturation(SPO2) was measured at 1, 2, 3, 5, 10, 15, 30, 60, 120 minutes by pulse oximeter; (3) Evaluation of the oxygen saving benefit ratio: SPO2 was measured at 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 L/min using CNC, the standard nasal cannula (SCN) and the new CNC. RESULTS: (1) During two hours of oxygen therapy, the values of PaO2 and SaO2 in the CNC group were always higher than those in the SNC group (P < 0.05); (2) When the supply flow to CNC was set at 0.5 L/min, 1.0 L/min, 1.5 L/min, 2.0 L/min seperately, the oxygen saving benefit ratio of CNC to SNC was 2.6:1, 1.8:1, 1.8:1 and 1.5:1 respectively. (3) The oxygen saving benefit ratio was comparable between CNC made in China and that made in foreign country. CONCLUSIONS: It was confirmed that CNC saved oxygen at different flows of oxygen, and the oxygen saving benefit ratio was higher at lower flows than that at higher flows.

Adult↗
PubMed1999

[Intercellular adhesion molecule-1 expression in experimental liver fibrosis].

OBJECTIVE: To explore the role of intercellular adhesion molecule-1 (ICAM-1) in experimental liver fibrosis. METHODS: Experimental liver fibrosis models of rats were induced by high fat diet, low fat diet plus ethanol, high fat diet plus ethanol, and carbon tetrachloride subcutaneous injection respectively. At sacrifice, liver pathologic changes were studied and ICAM-1 expression was evaluated with immunohistochemistry by using a monoclonal antibody. RESULTS: ICAM-1 expression was observed in the hepatocellular membrane; ICAM-1 positive hepatocytes were localized in zones of portal tract with focal necrosis and inflammatory damage. Staining for ICAM-1 was associated with the degree of liver inflammation and fibrosis. In the different models, the intensity of ICAM-1 expression was different; It ranged in an increasing order from high fat diet, low fat diet plus ethanol, high fat diet plus ethanol, and carbon tetrachloride model. The strongest reactivity for ICAM-1 was seen in carbon tetrachloride model (P < 0.05), the difference was significant as compared with the other models. However, there was no significant difference among the three other models (P > 0.05). CONCLUSION: Upregulation of ICAM-1 expression in experimental liver fibrosis may be related with liver fibrogenesis.

Animals↗
PubMed1999

[Effects of Kupffer cells stimulated by triglyceride and very low-density lipoprotein on proliferation of rat hepatic stellate cells].

OBJECTIVE: To study the effects of Kupffer cell-conditioned medium (KCCM) derived from triglyceride and very low-density lipoprotein (VLDL) treatment on proliferation of rat hepatic stellate cells (HSC). METHODS: HSC and Kupffer cells were isolated from liver of Wistar rats by in situ perfusion with pronase and collagenase and density gradient centrifugation with Nycodenz and then cultured. KCCM was prepared and MTT colorimetric assay was used to detect HSC proliferation. RESULTS: HSC and Kupffer cells were isolated successfully with high purity. 12.5 mg/L of triglyceride and 25 - 100 mg/L of VLDL promoted HSC proliferation (P < 0.05 or 0.01); KCCM + triglyceride and KCCM + VLDL might promote HSC proliferation as compared with a control group (P < 0.01). There was no significant difference between KCCM + triglyceride and KCCM + VLDL (P > 0.05). CONCLUSION: The technique for isolation of HSC and Kupffer cells described here is simple and reliable. Triglyceride, VLDL and KCCM stimulated by them may promote HSC proliferation and be associated with fatty liver and hepatic fibrogenesis.

Animals↗
PubMed1999

[Comparison of results of chamber angle examination by ultrasound biomicroscopy and gonioscopy].

OBJECTIVE: To compare the consistency of the chamber angles examined by ultrasound biomicroscope (UBM) and gonioscope and provide gonioscopic examination with new methods and technology. METHODS: 10 patients (20 eyes) were selected for the research. The same eyes were examined by UBM and gonioscope in turns. The results from the two methods were compared and the data were analyzed with Spearman correlation test. RESULTS: The results of two methods of chamber angle examination were well consistent when the angle was wide, but the consistency was not good when it was narrow. The angle examined by a gonioscope was wider than that by UBM. When the iris root insertion was evaluated in a narrow angle, the consistency was also not good, and when the peripheral iris morphology was evaluated, there were almost inconsistent results in one-fourth of the patients. CONCLUSIONS: The results of chamber angle examined by a gonioscope show a little wider than its natural status. Especially, it is difficult to distinguish the functional closure from the adhesive closure. Under the influence of light, the determination of iris root insertion by a gonioscope has a sense of conjecture. When peripheral iris morphology is evaluated, the influence of irregular iris might result in a wrong conclusion. Therefore, the technique of gonioscopic examination should be improved.

Adult↗
PubMed1999

[Low-molecular-weight chromium-binding substances in hepatic and nephric tissues of chromium-exposed rats].

Male Wistar rats were injected intraperitoneally with potassium dichromate(2.55 mg Cr6+ per kg body weight) for 7 days, and were observed continuously for 7 days after stopping Cr injection. The results were that concentrations of chromium-binding substances (HMW-Cr, LMW-Cr, and MMW-Cr) increased significantly with the extension of Cr injection time; MMW-Cr was not found in the control group. MMW-Cr may be a valuable indicator in diagnosing chromium toxication. It was efficient to use Sephadex G-50 column chromatography and ultra-violet absorption spectrometry-atomic absorption spectrophotometry in isolation, and then it was followed by quantitative analysis of chromium-binding substances.

Animals↗
PubMed1999

[Analysis on chemical composition of genus Pueraria stems from China].

OBJECTIVE: To provide scientific basis for developing and utilizing Pueraria stems. METHOD: The contents of total flavonoid were determined by means of UV spectrophotometry. The isoflavones in stems and roots of nine species of genus Pueraria were analyzed by TLC. RESULTS: The stems and roots are similar in chemical composition. CONCLUSION: Pueraria stems as a potential resource could be used as a substitute for Pueraria roots.

Chromatography, Thin Layer↗
PubMed1998

cGMP modulates basal and activated microvessel permeability independently of [Ca2+]i.

To investigate the mechanisms whereby guanosine 3',5'-cyclic monophosphate (cGMP) modulates microvessel permeability in vivo, we measured changes in microvessel hydraulic conductivity (Lp) and endothelial cytoplasmic Ca2+ concentration ([Ca2+]i) in response to the cGMP analogs 8-bromo-cGMP (8-BrcGMP) and 8-(p-chlorophenylthio)cGMP (8-pCPT-cGMP) in the presence and absence of inflammatory stimuli in intact individually perfused microvessels in frog and rat mesenteries. The cGMP analog caused a transient increase in Lp and potentiated ATP or bradykinin-induced increases in Lp in frog and rat mesenteric microvessels, respectively. The mean peak value of the test Lp/control Lp after exposure to 8-BrcGMP was 5.3 +/- 0.5 in frog microvessels and 2.8 +/- 0.4 in rat microvessels. The ATP-induced increase in Lp in frog microvessels was further raised by 8-BrcGMP from 7.0 +/- 0.9 to 12.4 +/- 1.9 times the control. In rat mesenteric microvessels, the bradykinin-induced increase in Lp was potentiated by 8-BrcGMP from 4.8 +/- 0.4 to 8.3 +/- 1.3 times the control and was suppressed by the guanylate cyclase inhibitor LY-83583 to 2.6 +/- 0.5 times the control. A similar but larger effect was found when using 8-pCPT-cGMP. In contrast to the actions of increased cGMP on microvessel permeability, cGMP analogs had no effect on basal endothelial [Ca2+]i and did not alter the magnitude and time course of ATP or bradykinin-induced increases in endothelial [Ca2+]i. These results suggested that an elevation of cGMP levels in endothelial cells is a necessary step to increase microvessel permeability in intact microvessels, and this regulatory process occurs downstream from Ca2+ influx, which differs from that reported in large-vessel endothelium in culture and in vascular smooth muscle cells. Experiments carried on microvessels in both frog and rat mesenteries provided a direct comparison of the endothelial cell regulatory mechanisms between species.

Adenosine Triphosphate↗
PubMed1998

Effects of isometric training on skeletal myosin heavy chain expression.

This study tested the hypothesis that an isometric resistance-training program induces upregulation of slow myosin heavy chain (MHC) expression in a fast-twitch skeletal muscle. Thus we studied the effects of two resistance-training programs on rodent medial gastrocnemius (MG) muscle that were designed to elicit repetitive isometric contractions (10-12 per set; 4 sets per session) of different duration (8 vs. 5 s) and activation frequency (100 vs. 60 Hz) per contraction during each training session (total of 6 and 12 sessions). Results showed that both training paradigms produced significant increases in muscle weight ( approximately 11-13%) after completion of training (P < 0.05). Significant transformations in MHC expression occurred and involved specifically a decrease in the relative expression of the fast type IIb MHC and concomitant increased expression of the fast type IIx MHC. These adaptations were observed in both the "white" and "red" regions of the MG, and they occurred at both the mRNA and protein levels. These adaptations were detected after only six training sessions. Neither of the training programs produced any change in the relative expression of either the slow type I MHC or the moderately fast type IIa MHC, which can be upregulated in the red MG by chronic functional overload. These findings show that the isometric protocols used in this investigation were not sufficient to induce the hypothesized changes in the myosin heavy chain isoform expression in rodent skeletal muscle.

Animals↗
PubMed1998

Interaction of hyperthyroidism and hindlimb suspension on skeletal myosin heavy chain expression.

We examined the novel interaction of hyperthyroidism and hindlimb suspension on the pattern of myosin heavy chain (MHC) expression (mRNA and protein) in skeletal muscles. Female Sprague-Dawley rats were assigned to four groups: 1) normal control (Con); 2) thyroid hormone treated [150 micrograms 3,5,3'-triiodothyronine (T3). kg-1. day-1] (T3); 3) hindlimb suspension (HS); or 4) T3-treated and HS (T3 + HS). Results show for the first time the novel observation that the combination T3 + HS induces a rapid and sustained, marked (80-90%) downregulation of type I MHC gene expression that is mirrored temporally by concomitant marked upregulation of type IIb MHC gene expression, as evidenced by the de novo synthesis of type IIb MHC protein in the soleus. The fast type IIx MHC isoform showed a differential response among the experimental groups, generally increasing with the separate and combined treatments in both the soleus and vastus intermedius muscles while decreasing in the plantaris muscles. The fast type IIa MHC was the least responsive to suspension of the MHCs and reflected its greatest responsiveness to T3 treatment while also undergoing differential adaptations in slow vs. fast muscle (increases vs. decreases, respectively). These results confirm previous findings that all four adult MHC genes are sensitive to T3 and suspension in a muscle-specific manner. In addition, we show that T3 + HS can interact synergistically to create novel adaptations in MHC expression that could not be observed when each factor was imposed separately.

Animals↗
PubMed1998

[Preliminary study on therapeutic effect of oxymatrine in treating patients with chronic hepatitis C].

OBJECTIVE: To evaluate the efficacy of oxymatrine in treating chronic hepatitis C and its mechanism. METHODS: Forty-three patient were divided randomly into the treated group (20 cases) and the control group (23 cases). The treated group was given oxymatrine 600 mg per day intramuscularly, and the control group was given the general liver protective agents such as vitamins. The therapeutic course of both groups was 3 months. RESULTS: HCVRNA of 8 in 17 cases (47.1%) of the treated group converted to negative, while in 18 cases of the control group, the negative conversion only took place in 1 patient (5.6%), the negative conversion rate was significantly higher in the treated group than that in the control group (P < 0.05). The normalization rates of serum alanine transaminase (ALT) of the treated group after 1 month and 2 months treatment was higher than that of the control group, but after 3 months treatment, the normalization rates of the two groups were not different significantly. Plasma level of soluble interleukin-2 receptor and serum level of collagen type IV in the treated group were lowered significantly after treatment, but in the control group, there were no significant change, the difference between the two groups was significant (P < 0.01, P < 0.05). CONCLUSION: Oxymatrine is effective in inhibiting proliferation of HCV, antagonisting liver fibrosis and regulating immune reaction of the host, so it could be a safe, effective drug in treating chronic hepatitis C.

Adolescent↗
PubMed1998

Influence of space conditions on photosynthetic pigment contents and chloroplast ultrastructure of maize leaves.

Dried seeds of maize inbred lines were carried by recoverable satellite to space conditions at an altitude of 175-253 km from sea level for 15 d. The effects of space flight on ultrastructure and photosynthetic pigment contents of maize leaves were studied. Various changes in structure were observed. Chloroplast envelope membrane notch, swelling of thylakoids, less granum stacks and stroma thylakoid membranes, and changes of chloroplast contour were often seen. The contents of chlorophyll a, chlorophyll b, and chlorophyll a+b and carotenoids tended to be lower, but Ca/Cb ratio tended to be higher in the leaves from space flight maize in comparison with ground control.

Chlorophyll↗
PubMed1998

[Diagnostic significance of cuticular patterns on corolla surface from Pueraria spp].

OBJECTIVE: To provide reference materials for the classification and identification of Pueraria spp. by studying the cuticular patterns on corolla surface. METHOD: The cuticular patterns of corolla were observed under SEM (scanning electron microscope). RESULT: The species of the genus Pueraria are defferent from each other in cuticular patterns. CONCLUSION: The diagnostic characters of the cuticular patterns on corolla surface can be used for the classification and identification of Pueraria spp.

Fabaceae↗
PubMed1998

[The role of nitric oxide in hyperdynamic circulation in portal hypertensive rats].

OBJECTIVE: To evaluate the role of nitric oxide (NO) in hyper-hemodynamics in portal hypertension, we investigated the effects of nitric oxide synthase inhibitor L-NMMA with or without L-arginine, the substrate for enzyme NO synthase on the systemic and splanchnic hemodynamics in portal hypertensive rats. METHOD: Ninety-seven male Sprague-Dawley rats were divided into four groups: intrahepatic portal hypertension (IHPH, n = 23) by injection of CCl4, prehepatic portal hypertension (PHPH, n = 26) by stenosis of the portal vein, end-to-side portacaval shunt (PCS, n = 23), and sham-operated controls (SO, n = 25). Animals of each group were divided into three subgroups: systemic administration of L-NMMA (50 mg/kg BW, 1 ml), L-NMMA (50 mg/kg BW, 0.5 ml) plus L-arginine (30 mg/kg BW, 0.5 ml), and normal saline solution (1 ml). The radioactive microsphere method was used for hemodynamic study. RESULT: There was the characteristic of hyperdynamic circulatory state including increased cardiac output and splanchnic blood flow, decreased mean arterial blood pressure, total peripheral vascular resistance and splanchnic vascular resistance in IHPH, PHPH and PCS rats. The hyperdynamic circulatory state in IHPH, PHPH and PCS rats could be effectively reversed by L-NMMA to the resting values of hemodynamics in SO rats, but not the levels after administration of L-NMMA in SO rats, indicating that there is excessive production of NO in portal hypertensive and PCS rats. Administration of L-arginine counterbalanced the effects of L-NMMA on hyperdynamic circulatory state in portal hypertensive and PCS rats. CONCLUSION: NO is an important mediator of hyperdynamic circulation in portal hypertension.

Animals↗
PubMed1997

High-efficiency stable gene transfer of adenovirus into mammalian cells using ionizing radiation.

We report a novel method for targeting adenovirus-mediated gene delivery. By irradiating mammalian cells prior to adenoviral transduction, adenoviral gene transfer is greatly improved and the adenoviral genome integrates into cellular DNA. In this work, human and rodent cell lines were irradiated and subsequently transduced with the adenovirus vector Ad5CMVlacZ. Initial levels of transduction were as much as 40-fold higher in irradiated cells, and this improvement in transduction was radiation dose dependent. The duration of lacZ expression in irradiated cells was also much longer than in nonirradiated cells and reached a plateau after 21 days. At doses of 7 Gy, long-term (< 50 day) expression of lacZ could be detected in 15% of cells by flow cytometry. This long-lasting expression of lacZ was due to viral DNA integration into the host genome. Thus, pretreatment of cells with ionizing radiation improves both immediate transduction efficiency and duration of transgene expression. This may lead to the development of new protocols combining radiation and gene therapy in treating human malignancy.

3T3 Cells↗
PubMed1997

Interaction of thyroid state and denervation on skeletal myosin heavy chain expression.

The goal of this study was to examine the effects of altered thyroid state and denervation (Den) on skeletal myosin heavy chain (MHC) expression in the plantaris and soleus muscles. Rats were subjected to unilateral denervation (Den) and randomly assigned to one of three groups: (1) euthyroid; (2) hyperthyroid; (3) and hypothyroid. Denervation caused severe muscle atrophy and muscle-type specific MHC transformation. Denervation transformed the soleus to a faster muscle, and its effects required the presence of circulating thyroid hormone. In contrast, denervation transformed the plantaris to a slower muscle independently of thyroid state. Furthermore, thyroid hormone effects did not depend upon innervation status in the soleus, while they required the presence of the nerve in the plantaris. Collectively, these findings suggest that both thyroid hormone and intact nerve (a) differentially affect MHC transformations in fast and slow muscle; and (b) are important factors in regulating the optimal expression of both type I and IIB MHC genes. This research suggests that for patients with nerve damage and/or paralysis, both muscle mass and biochemical properties can also be affected by the thyroid state.

Animals↗
PubMed1997

Effect of nitric oxide synthase inhibitors on basal microvessel permeability and endothelial cell [Ca2+]i.

We evaluated the role of basal nitric oxide (NO) release in the regulation of microvessel permeability under resting conditions. We measured changes in microvessel hydraulic conductivity (Lp) and endothelial cytoplasmic calcium concentration ([Ca2+]i) after application of NO synthase (NOS) inhibitors to the lumen of individually perfused frog mesenteric venular microvessels. NOS inhibitors caused a transient increase in Lp. The mean ratios of peak test Lp values relative to control values in the presence of N omega-nitro-L-arginine methyl ester (L-NAME) at concentrations of 1, 10, and 100 microM were 2.5 +/- 0.6, 2.9 +/- 0.7, and 4.8 +/- 0.4, respectively. N omega-monomethyl-L-arginine (L-NMMA) showed a similar effect and a biologically inactive isomer of L-NMMA, D-NMMA, showed no effect. These results demonstrate that basal levels of NO play a role in modulating microvessel permeability different from that due to NO produced in response to inflammatory agents. In the activated state NOS inhibitors attenuated the increased microvessel permeability in response to ionomycin and ATP [P. He, B. Liu, and F. E. Curry. Am. J. Physiol. 272 (Heart Circ. Physiol. 41): H176-H185, 1997]. The transient increase in basal permeability induced by NOS inhibitors was not accompanied by an increase in endothelial cell [Ca2+]i and did not require the presence of extracellular calcium. Application of ketotifen, a mast cell stabilizer, and an iron-chelating reagent, deferoxamine mesylate, attenuated the transient increase in Lp induced by L-NMMA, suggesting that basal NO may have an important antioxidant role in regulating normal permeability.

Animals↗