Biomedical subjects

S Chen

Publications and source records attributed to S Chen.

At least 757 records · Page 42Linked to original sources

PubMed1998

[Construction of a human factor VIII gene-containing plasmid and its expression in Cos-7 cells].

OBJECTIVE: To construct an eukaryotic expressing plasmid--pAd CMV Link F VIII DB and express it in Cos-7 cells. METHODS: An eukaryotic expressing plasmid--pAd CMV Link F VIII DB was constructed by inserting human factor VIII cDNA (F VIII DB, 4.6 kb), in which most part of B domain was deleted, into an adenovirus sequence-containing plasmid, and then Cos-7 cells were transfected with the constructed plasmid by liposome-mediated gene transfer method. F VIII DB mRNA, F VIII: Ag and F VIII: C in the transfected Cos-7 cells were assayed by RT-PCR, ELISA and one-stage method, respectively, at 24, 48 and 72 hours (hrs) after transfection. RESULTS: F VIII DB mRNA was positive and, F VIII: Ag and F VIII: C were 18 ng/10(6) cells/24 hrs and 0.6 U/10(6) cells/24 hrs, respectively at 72 hrs after transfection, which was comparable to 60% of the activity produced by 100 micrograms/L F VIII in normal human plasma. CONCLUSION: The constructed plasmid is proved to be expressed in Cos-7 cells.

Adenoviruses, Human↗

PubMed1998

Herbimycin A enhances apoptotic effect of chemotherapeutic drugs on K562 cells.

OBJECTIVES: To explore the anti-apoptotic mechanism and the effective apoptosis-inducing method in chronic myelogenous leukemia (CML) cells. METHODS: K562 cell line was used to observe the effect of combination of herbimycin A (HMA), a tyrosine kinase inhibitor, and chemotherapeutic agents on the induction of apoptosis. RESULTS: HMA or chemotherapeutic agents could inhibit the proliferation but not significantly induce apoptosis of K562 cells. However, HMA significantly enhanced apoptosis when combined with chemotherapeutic agents. Addition of sulfhydryl compound to the cultures to conjugate HMA completely abrogated this enhancing effect on K562 cells. CONCLUSIONS: HMA increases the sensitivity of CML cells to chemotherapeutic agents by inactivating tyrosine kinase activity. It is promising that combination of HMA with conventional chemotherapeutic drugs may be a new strategy in the treatment of CML.

Antibiotics, Antineoplastic↗

PubMed1998

[Studies of tumor necrosis factor-alpha and red cell immunity state in multiple myeloma].

OBJECTIVE: To explore factors in the pathogenesis of multiple myeloma (MM). METHODS: The plasma level of tumor necrosis factor-alpha (TNF alpha) was measured by immunoassay in 21 MM patients, and red cell immunologic function was assayed in 16 patients. RESULTS: There was no difference in TNF alpha levels among patients with either fulminant MM or stable MM and normal controls. The rosette formation rate of red cell C3 bR and red cell immune complex was significantly lower in MM patients than in the controls. CONCLUSION: MM patients might have impaired monocyte-phagocyte system and red cell immune function.

Adult↗

PubMed1998

[A molecular and epidemiology study in patients with ventilator-associated pneumonia].

OBJECTIVE: To evaluate causative agents in patients with ventilator-associated (VA) pneumonia epidemiologically, then to provide useful suggestion for diagnosis and treatment of VA pneumonia. METHOD: Prospectively, a protected specimens brush was used to obtain the secretion of lower respiratory tract of 65 patients, who had been receiving mechanical ventilation or tracheostomy for more than 72 hours. At the same time, other samples were collected from the relevant places, including pharyngeal and gastric juice of patients as well as other persons, ward's air. The secretion obtained were cultured with a quantitative method. Then all bacteria isolated were studied with the analysis of pattern of plasmids and chromosomal restriction endonuclease. RESULT: It was showed that the route of infection of the Gram-negative bacilli in VA pneumonia (19 cases) was intrinsic, a retrograde colonization from patient's stomach, that was the pattern of clonization from stomach to pharynx, then into lower respiratory tract, and the Gram-positive staphylococcus spread mainly through the ward's air, then directly into lower respiratory tract, or extrinsic (20 cases). CONCLUSION: The Gram-positive staphylococcus is also major disease-producing germs in VA pneumonia, and the infection routes of G+ and G- bacteria might be different.

Adult↗

PubMed1998

Pharmacokinetics of intravenous arsenic trioxide in the treatment of acute promyelocytic leukemia.

OBJECTIVE: To study the pharmacokinetics and metabolism of arsenic trioixide (As2O3) and its main side effects. METHOD: As2O3 was administered intravenously at the dose of 10 mg per day for the treatment of 8 relapsed acute promyelocytic leukemia (APL) patients. The arsenic content was measured by Gas-phase chromatography. RESULTS: The plasma maximal concentration (Cpmax) was 0.94 +/- 0.37 mg/L (x +/- s), time to peak concentration (Tp) was 4 hours, plasma distribution half-time (t1/2 alpha) and elimination half-time (t1/2 beta) were 0.89 +/- 0.29 hours and 12.13 +/- 3.31 hours, respectively. Apparent distribution volume (Vc) was 3.83 +/- 0.45 L, system clearance (CLs) was 1.43 +/- 0.17 L/h, and area under curve (AUC) was 7.25 +/- 0.97 mg.h/L. The continuous administration of As2O3 did not alter its pharmacokinetic behaviors. During As2O3 treatment, 24-hour arsenic content in urine accounted for 1%-8% of the daily dose (10 mg). When arsenic accumulation in hair and nail increased continuously, the peak concentration could be five to seven-fold higher than that of pre-treatment. Importantly, arsenic contents in both urine and hair or nail declined gradually after drug withdrawal. No bone marrow suppression or severe organ-impairment was found. CONCLUSION: As2O3 is a relatively safe and effective remedy in the treatment of patients with relapsed APL, in spite of certain degree of arsenic accumulation in some tissues.

Adolescent↗

PubMed1998

[Quantitative determination of niphensamide by high performance liquid chromatography (HPLC)].

An HPLC method for the quantitative determination of Niphensamide in pesticide powder was developed. Column:Micropak-CH 5 microns (300 mm x 4.0 mm i.d.), mobile phase: CH3OH-H2O(1:1), detector: UV 254 nm, flow rate: 0.7 mL/min, column temperature: 25 degrees C. Under the above conditions, Niphensamide and other components were separated from each other. The method is simple, rapid, sensitive and accurate.

Chromatography, High Pressure Liquid↗

PubMed1998

[Adenosine facilitates carotid baroreflex in rats].

The effects of adenosine (Ado) on the carotid baroreflex were studied in 27 anesthetized rats with isolated carotid sinus perfusion. The results obtained were as follows: (1) By perfusing the isolated carotid sinus with adenosine (125 mumol/L), the functional curve of baroreflex was shifted to the left and downward, with the peak slope (PS) increased from 0.37 +/- 0.02 to 0.55 +/- 0.02 kPa/kPa (P < 0.001) and the reflex decrease in mean arterial pressure (RD) enhanced from 5.53 +/- 0.12 to 7.76 +/- 0.36 kPa (P < 0.001). Meanwhile, the threshold pressure (TP), equilibrium pressure (EP) and saturation pressure (SP) were significantly decreased from 8.60 +/- 0.27 to 5.63 +/- 0.11 kPa (P < 0.001), 12.53 +/- 0.30 to 10.89 +/- 0.29 kPa (P < 0.01) and 23.69 +/- 0.15 to 20.18 +/- 0.55 kPa (P < 0.001), respectively. Among the functional parameters of carotid baroreflex, the changes of RD, PS and TP induced by Ado were dose-dependent. (2) By pretreatment with (8-cyclopentyl-1, 3-dipropylxanthine, 0.134 mmol/L), a selective adenosine A1-receptor antagonist, the above effects of Ado on carotid baroreflex were abolished. (3) The Ado-induced changes of baroreflex were also eliminated as the carotid sinus was pretreated with KATP channel blocker glibenclamide (10 mumol/L). The results strongly suggest that the carotid baroreflex could be facilitated by Ado. It is proposed that the facilitatory action of Ado on carotid baroreflex may be resulted from the opening of KATP channels mediated by Ado A1-receptors.

Adenosine↗

PubMed1998

[The study of platelet function in patients with chronic pulmonary heart disease].

OBJECTIVE: To study the platelet function in patients with chronic pulmonary heart disease. METHOD: Subjects were divided into three groups (cor pulmonale exacerbation, cor pulmonale remission stage and normal control). Platelet adhesion rate (PAdT), platelet aggregation rate(PAgT), alpha-granule membrane protein (GMP-140) and glycoproteinII were measured by radioimmunoassay, flow cytometry and other methods. RESULT: In cor pulmonale exacerbation, the values of PAdT, PAgT, GMP-140 and GPII were31% +/- 16%, 14% +/- 8%, 190 +/- 49 molecule/platelet and 145% +/- 36% respectively. In cor pulmonale remission stage, the values were 33% +/- 13%, 38% +/- 16%, 178 +/- 33 molecule/platelet and 137% +/- 48% respectively. These findings showed that the values of PAdT, GMP-140 and GPII in cor pulmonale exacerbation were markedly increased, whereas PAgT was significantly reduced. However, PAdT, PAgT, GMP-140 and GPII in remission stage were all higher than that of normal group. CONCLUSION: In vivo platelet activation is indeed present in patients with chronic pulmonary heart disease.

Aged↗

PubMed1998

[L-arginine prolonged the efficacy of inhaled nitric oxide on the inhibition of pulmonary hypertension].

OBJECTIVE: The aim of this study is to investigate the effects of L-arginine, the substrate of nitric oxide (NO) on the duration of nitric oxide selective decrease of pulmonary hypertension. To assess whether combined use of inhaled nitric oxide and venous administered L-arginine can improve the efficacy of inhaled NO on the inhibition of hypoxia induced pulmonary hypertension. METHOD: Eight pigs with hypoxic pulmonary hypertension received either inhaled NO(12-15 ppm) for 10 minutes or inhaled NO plus venous administrered L-arginine(10 g), then hemodynamic parameters were recorded. RESULT: NO inhalation significantly inhibited hypoxic induced pulmonary hypertension with pulmonary arterial pressure decreasing from 4.2 +/- 0.4 kPa to 2.5 +/- 0.5 kPa(P < 0.01) and pulmonary vascular resistance from 56 +/- 25 kPa.s.L-1 to 31 +/- 13 kPa.s.L-1(P < 0.01), but this just lasted for 3-5 minutes after stopping inhalation; combined use of L-arginine infusion did not further decrease pulmonary arterial pressure, but significantly prolonged the inhibitory effect of inhaled NO on pulmonary hypertension (20 times) as compared with inhaled NO only. CONCLUSION: With the existence of exogenous NO, supplement of NO substrate L-arginine produced a synesgetic inhibition effect on hypoxic induced pulmonary hypertension.

Administration, Inhalation↗

PubMed1998

Effect of intracarotid injection of adenosine on the activity of RVLM neurons in barodenervated rats.

To observe the effect of intracarotid administration of adenosine on neurons in the rostral ventrolateral medulla (RVLM) region, 72 spontaneous active units were extracellularly recorded from 28 Sprague-Dawley rats with sino-aortic denervation. The results obtained are as follows: (1) intracarotid administration of Ado (25 micrograms/kg) reduced the discharge rate from (23.5 +/- 3.0) to (16.5 +/- 2.6) spikes/s (P < 0.001) in 31 out of 36 RVLM neurons, while the blood pressure and heart rate had no significant change (P > 0.05); (2) 8-phenyltheophylline (8-PT, 15 micrograms/kg), a nonselective adenosine receptor antagonist, and 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 50 micrograms/kg), a selective A1 adenosine receptor antagonist, completely blocked the inhibitory effects of Ado in 24 units; and (3) in 12 units, glibenclamide (500 micrograms/kg), a blocker of ATP-sensitive potassium channel, abolished the effect of Ado. These results indicate that Ado can induce an inhibition of spontaneous electrical activity of RVLM neurons, an effect which is mediated by adenosine A1-receptor with the involvement of ATP-sensitive potassium channels.

Adenosine↗

PubMed1998

[The observation on infection of trasgenic mice (PVR Tg21) with polioviruses type 3].

OBJECTIVE: To test and verify whether PVR Tg21 transgenic mice can be used as an animal model or not. METHODS: PVR Tg21 transgenic mice were infected with 3 poliovirus strains with different neurovirulence intraspinally. RESULTS: All the mice showed clinical paralysis with characteristic lesions in neurons. The symptoms varied with different potency of virus. The onset of clinical paralysis time for inoculated mice were approximately 2 days with Leon virus, 5 days with Sabin strain, and 4 days with Vaccine-321. More than 90% of mice inoculated with Leon strain died within 3 days after clinical paralysis and only 35% mice inoculated with Sabin-3 died at average of 6 days, and the PD50 are 10(1.1), 10(2.6), and 10(4.97) TCID50 and LD50 are 10(1.1), 10(3.33) and 10(5.33) TCID50, respectively. Different virus inoculated intraspinally caused different histopathological lesions. CONCLUSIONS: The PVR Tg21 transgenic mice could be a new animal model for neurovirulent evaluation of poliovaccines and epidemiological surveillance.

Animals↗

PubMed1998

[Adenosine facilitates carotid baroreceptor activity in rats].

The effects of adenosine (Ado) on the carotid baroreceptor were studied in 36 anesthetized rats with isolated carotid sinus perfusion by recording the sinus nerve afferent activity. The results obtained were as follows: (1) By perfusing the isolated carotid sinus with 75 mumol/L Ado, the functional curve for intrasinus pressure(ISP)-integral of sinus nerve activity (ISNA) relation was shifted to the left and upward with peak slope (PS) increased from (18.75 +/- 0.12)%/kPa to (22.21 +/- 0.11)%/kPa (P < 0.001) and the peak integral value (PIV) enhanced from (209.83 +/- 2.57)% to (239.17 +/- 1.75)% (P < 0.001), while the threshold pressure (TP) and saturation pressure (SP) were significantly decreased from 8.57 +/- 0.24 to 7.15 +/- 0.23 kPa (P < 0.001) and from 22.99 +/- 0.34 to 21.21 +/- 0.43 kPa (P < 0.01). By perfusing with high concentrations of Ado (125 and 175 mumol/L), the curves for ISP-ISNA relation were shifted to the left and upward further and the changes of the functional parameters such as PS, TP and SP were dose-dependent. (2) By pretreatment with 8-cyclopentyl-1,3-dipropylxanthine (0.134 mmol/L), a selective adenosine A1-receptor antagonist, the above mentioned effects of Ado on carotid baroreceptor activity were abolished. (3) The Ado-induced increase in sinus nerve afferent activity could be eliminated by pretreatment with KATP channel blocker glibenclamide (10 mumol/L). The above results suggest that Ado exerts a facilitatory action on the isolated carotid baroreceptor and such an action of Ado may be attributed to the opening of KATP channels, which is mediated by A1-receptors.

Adenosine↗

PubMed1998

[Effects of dexamethasone on apoptosis of airway inflammatory cells in asthmatic guinea-pigs].

OBJECTIVE: Clearance of airway inflammatory cells is the key point of therapeutic effect in asthma. Apoptosis, a form of cell death, is thought to be critically important to promote the clearance of inflammatory cells and the resolution of inflammation. To investigate the effects of dexamethasone on apoptosis of airway inflammatory cells in asthma showed be very important. METHOD: Dexamethasone was used for the treatment of asthma model of guinea pigs set up by inhaling ovalbumin. Apoptotic cells were labelled with TdT-mediated dUTP nick end labeling(TUNEL) technique on formalin-fixed paraffin-embedded trachea and lung tissue sections. By way of immunohistochemistry, eosinophils were stained with EG2 antibody and T lymphocytes with CD3+, CD4+ and CD8+ antibodies on sections. RESULT: (1) The quantity of airway eosinophils and lymphocytes decreased in dexamethasone group, which could not be observed in the control one (P < 0.01). (2) Apoptotic index of lymphocytes was significantly elevated following dexamethasone treatment(P < 0.05). But no difference was found in the proportion of apoptotic eosinophils between these two groups. (3) The percentage of EG2 positive eosinophils and CD4+ positive lymphocytes decreased significantly following dexamethasone treatment. On the contrary, the number of CD8+ lymphocytes increased in dexamethasone group when compared with the control one (P < 0.05). CONCLUSION: (1) The quantity of airway eosinophils decreases following dexamethasone treatment in guinea-pigs asthma, and its mechanism may not be ascribed mainly to the apoptosis of eosinophils. (2) The number of lymphocytes, mainly CD4+, decreased following dexamethasone treatment in guinea-pig airways, and apoptosis may represent the mechanism that promotes the clearance of lymphocytes in asthma.

Animals↗

PubMed1998

[Determination of mephenytoin enantiomers in human urine using chiral capillary chromatography and its application in metabolism polymorphism study].

The determination of mephenytoin enantiomers in human urine using chiral capillary chromatography is described. MP in urine was extracted with using dichloroethane and the organic layer was washed with acidic and basic aqueous solution. The organic phase was evaporated to dryness under nitrogen on water bath (55 degrees C). The residue was dissolved in 10 microL ethyl acetate and 1 microL was injected into the GC. MP enantiomers was separated on a Chirasil-Val SFOT column with nitrogen as carrier gas and FID as detector. The linear relationship was obtained over the concentration range of 115-690 micrograms/L (r = 0.9913 for S-MP and r = 0.9934 for R-MP) with a detection limit of 60 ng MP enantiomers/mL urine. The recoveries were 74.41% for S-MP and 73.78% for R-MP. The relative standard deviation within day and between days were less than 6.5%. The method was used to study the metabolism polymorphism of 32 volunteers. The S/R ratio was calculated to express interindividual variation in metabolism, in which, the S/R ratio of 5 subjects was more than 0.95, as the poor metabolizers and that of the others was less than 0.8, as the extensive metabolizers.

Anticonvulsants↗

PubMed1998

[The effect of Codonopsis pilosula (Franch.) Nannf. on gastric acid, serum gastrin and plasma somatostatin concentration in dogs].

The results were obtained by oral administration of the decoction of Codonopsis pilosula in three different doses(10 g, 20 g, 40 g) to 5 dogs with Heidenhain pouch. No significant changes occurred in the acidity output of Heidenhain pouch and plasma somatostatin concentration out of the oral administration (P > 0.05). A significant increase occurred in serum gastrin concentration (P < 0.05 or P < 0.01) 150 min after a dose of 10 g, 90 min and 150 min after doses of 20 g, and 30 min, 60 min, and 150 min after doses of 40 g.

Animals↗

PubMed1998

[An epidemiological survey of cleft lip and cleft palate in Fujian province].

OBJECTIVE: To find out the incidence of cleft lip and cleft palate in Fujian provice and to analysis the factors of its deformity. METHODS: From Oct. 1986 to Dec. 1992, the birth defect monitoring was carried out in 22 hospitals in Fujian province. RESULTS: It was found that there were 204 cases of cleft lip (CL) and cleft palate (CP) in 139,882 perinatals. The incidence rate of CL and/or CP was 1.46@1000. Annual incidence rate of CL and/or CP had not found any significant change. CONCLUSION: Among the 204 cases 28 had other deformities. The incidence rate of CL and/or CP related to maternal age, birth order, smoking factors were studied.

Adolescent↗

PubMed1998

[Correlation between accumulation of (99m)Tc-MIBI in breast cancer or benign lesion, cell proliferation and angiogenesis].

OBJECTIVE: To study the accumulation of (99m)Tc-MIBI in breast cancer or benign lesions and the correlation between cell proliferation and angiogenesis. METHOD: (99m)Tc-MIBI positive imaging was performed on 38 patients with palpable breast mass. A ratio of radioactivity value of mass to normal tissue was assessed 10 minutes after injection of (99m)Tc-MIBI in posterior oblique view. Cell proliferation and angiogenesis were assessed by immunostaining of proliferating cell nuclear antigen (PCNA) and ulex europaeus I lectin (UEA- I). Data were analyzed by T-test, correlation and regression analysis. RESULT: We studied 17 true-positive, 5 false-negative, 15 true-negative, and 1 false positive patients (chi(2) = 18.74, P < 0.001). In patients with positive (99m)Tc-MIBI scans, the diameter of mass (4.00 +/- 1.95 cm) was larger and the percentage of PCNA positive cell (74.13% +/- 13.84%) was significantly higher than that in patients with negative scans (2.14 +/- 1.00 cm, 43.76% +/- 20.78%, P < 0.01). No significant evidence of difference between the number of angiogenic vessels of the two groups (181.3 +/- 71.7, 138.3 +/- 103.0, P = 0.141). The accumulation of (99m)Tc-MIBI was most strongly correlated with the percentage of PCNA positive cell (r = 0.56, P = 0.000), but was not related to the number of vessels (r = 0.31, P = 0.056). In stepwise regression analysis, the variance number of vessels was not included in the model. CONCLUSION: The accumulation of (99m)Tc-MIBI in breast cancer is an indicator of cell proliferation, and no evident relationship with angiogenesis has been found.

Adult↗

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↗