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Biomedical subjects

Q Chen

Publications and source records attributed to Q Chen.

At least 343 records · Page 19Linked to original sources
PubMed1999

Disposition of ivermectin and cyclosporin A in CF-1 mice deficient in mdr1a P-glycoprotein.

The pharmacokinetics and hepatic metabolism of [3H] ivermectin (IVM) and [3H]cyclosporin A (CSA) were investigated in a subpopulation of the CF-1 mouse stock naturally deficient in mdr1a p-glycoprotein (PGP). A survey of key drug-metabolizing activities in liver fractions from PGP-deficient (-/-) or wild-type (+/+) animals indicated the two subpopulations are not different in hepatic metabolic activity and capacity. Intravenous pharmacokinetics of CSA were identical between the two groups, and results from microsomal incubations indicated similar biotransformation of IVM and CSA in liver. Intestinal excretion of [3H]IVM and [3H]CSA was enhanced in PGP (+/+) animals. Absence of PGP resulted in higher blood concentrations of IVM after oral dosing, suggesting enhanced absorption of IVM in (-/-) mice. Concentrations of [3H]IVM and [3H]CSA were always greater in the brains of (-/-) mice compared with (+/+) mice after either i.v. or oral administration. In contrast, liver concentrations of either compound were not different between (+/+) and (-/-) animals after an i.v. dose. These results show the PGP (-/-) and (+/+) subpopulations of CF-1 mice are useful for studying the role of mdr1a PGP in systemic exposure and tissue disposition of PGP substrates in the absence of metabolism differences.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1999

Kinetics of thermal inactivation of penaeus penicillatus acid phosphatase

The kinetics of thermal inactivation of Penaeus penicillatus acid phosphatase have been studied using a kinetic method related to the substrate reaction during irreversible inhibition of the enzyme activity as previously described by Tsou (Adv. Enzymol. Relat. Areas Mol. Biol. (1988) 61, 381-436). The kinetics of thermal inactivation of the enzyme show that the reaction is irreversible. The microscopic rate constants were determined for thermal inactivation of free enzyme and the enzyme--substrate complex. The results show that the presence of substrate has a significant protective effect against thermal inactivation of the enzyme.

Journal Article↗
PubMed1999

Ventilation-perfusion MR imaging of the lung.

The assessment of regional ventilation in human lungs is important for the diagnosis and evaluation of a variety of pulmonary disorders, including pulmonary emphysema, diffuse lung disease (e.g., sarcoidosis, and pulmonary fibrosis), lung cancer, and pulmonary embolism. This article introduces new MR imaging techniques of pulmonary ventilation and perfusion that will provide a framework for assessing regional pulmonary functions of the lung.

Adult↗
PubMed1999

Ionizing radiation-induced, Bax-mediated cell death is dependent on activation of cysteine and serine proteases.

Bcl-2 family proteins and interleukin-1-beta converting enzyme/Caenorhabditis elegans cell death gene-3 (ICE/CED-3) family proteases (caspases) represent the basic regulators of apoptosis. However, the precise mechanism by which they interact is unclear. In this study, we found that gamma-radiation-induced apoptosis of leukemia cells was associated with activation of multiple caspases and bax up-regulation. Membrane changes and caspase activities were suppressed by specific caspase inhibitors. Similarly, the serine protease inhibitors z-Ala-Ala-Asp-cmk (AAD) and tosyl-lysine chloromethyl ketone (TLCK) also prevented caspase activation and poly(ADP-ribose) polymerase cleavage in vivo but had no effect on caspase activity in vitro. TLCK also prevented bax up-regulation as a result of its inhibitory effect on p53 function. Inhibitors of caspases and serine proteases partially prevented cell death, suggesting a caspase involvement in Bax-mediated cell death. We propose an ordering of signaling events in Bax-mediated cell death, including steps upstream and downstream of p53 and bax up-regulation.

Apoptosis↗
PubMed1999

Cor triatriatum in adults: three new cases and a brief review.

We report 3 cases of cor triatriatum that were diagnosed late, in the 4th and 5th decades of life. The presentations of these 2 men and 1 woman varied substantially, both in anatomic and symptomatic aspects. The woman had an associated complex congenital anomaly, which is not uncommon in cases of cor triatriatum. We present our cases, along with a review of this rare congenital cardiac anomaly.

Adult↗
PubMed1999

Clinical study on 118 cases of ulcerative colitis treated by integration of traditional Chinese and Western medicine.

118 cases of ulcerative colitis were treated by integration of traditional Chinese and Western medicine. Another 86 cases of ulcerative colitis were treated by simple western drugs as controls. The therapeutic effects for both groups were observed and compared after two therapeutic courses of 40 consecutive days. As a result, 39 cases were cured, 60 cases improved and 19 cases failed, with a total effective rate of 84% in the treatment group; in the control group, 15 cases were cured, 37 cases improved and 34 cases failed, with a total effective rate of 60.5%. Statistically, the difference was very significant (P < 0.01). It can be concluded that treatment of ulcerative colitis by the integrated method is superior to that by simple western drugs.

Adult↗
PubMed1999

[Study for the factors related to postpartum depression].

OBJECTIVE: To study the prevalence rate of postpartum depression(PD) and related factors. METHODS: 1,052 pregnant women were selected in random from our antenatal clinic from January to November, 1997 for mood study by hospital anxiety and depression (HAD), and 866 cases were further follow-up till 7 days after childbirth with Edinburgh postpartum depression scale (EPDS). RESULTS: The prevalence rate of PD was 15.01% by EPDS. Using single factor and mutifactorial stepwise regression analyses for the affected factors of PD, 7 factors were most strongly related to the onset of PD: they were women's health condition; the relationship between husband and wife; the medical workers' attitude during labor; husband's desire for boy child; the number of antenatal educational classes received; anxiety and depression mood during pregnancy. The number of educational classes received was negatively correlated with PD, while the other 6 factors were all positively correlated. CONCLUSION: The main factors related to PD are the mood of anxiety and depression during pregnancy.

Adult↗
PubMed1999

[Comparative changes in uterine artery blood flow waveforms in singleton and twin pregnancies].

OBJECTIVE: (1) To compare singleton and twin pregnancies with regard to changes in the Pulsatility Index (PI) of uterine arteries over the course of the pregnancy; (2) To examine the effect of the location of the placenta on the PI in the uterine arteries in twin pregnancies. METHODS: We prospectively studied the PI of uterine arteries in 99 women with uncomplicated singleton pregnancies and 24 women with uncomplicated twin pregnancies and examine the location of the placenta. RESULTS: In both the ipsilateral and contralateral uterine arteries, the PI exhibited a steady decrease toward term in singleton pregnancies. In twin pregnancies, the PI exhibited a steady decrease until 27 weeks of gestation and remained unchanged thereafter. The PI in the ipsilateral artery was consistently lower than that in the contralateral artery in singleton as well as twin pregnancies. The mean values of PI of the ipsilateral and contralateral uterine arteries of twin pregnancies was consistently lower than that of singleton pregnancies at any gestational week. CONCLUSIONS: The ipsilateral uterine artery contributes more to placental perfusion than does the contralateral uterine artery in twin as well as in singleton pregnancies. Twin pregnancies differed from singleton pregnancies with respect to changes in PI in the uterine artery according to gestational age. The PI of uterine arteries declined more rapidly and reached a plateau earlier in twin than in singleton pregnancies.

Arteries↗
PubMed1999

[Identification of three common G6PD gene mutations in Yi minority in Yunnan province].

OBJECTIVE: To identify three common G6PD gene mutations in Yi minority in Yunnan province. METHODS: G6PD gene mutation of 28 samples from G6PD deficient patients was detected by using amplification refractory mutation system(ARMS). Samples were collected from Yi minority in Yunnan province. RESULTS: In 28 cases, 22 were identified to be three known mutations, including 12 of 1388(G-->A), 9 of 1376(G-->T) and 1 of 95(A-->G). The remaining 6 cases were undefined. CONCLUSIONS: This is the first report of G6PD gene G1376T and A95G mutations in Yi minority. The three common mutations account for 78.6% of the 28 cases.

Alleles↗
PubMed1999

[Influence of roxithromycin combined with fleroxacin on bacterial biofilm induced by Pseudomonas aeruginosa].

OBJECTIVE: To investigate the influence of roxithromycin (RXM) on the production of glycocalyx (GLX) and the synergic effect of RXM and fleroxacin (FLRX) on P. Aeruginosa biofilms. METHODS: Bacterial biofilm (BF) was established and was influenced by RXM and FLRX with different concentrations. The samples were detected with scanning electron microscope and by a rapid method after BF was stained with AgNO3 solution. The synergism of antibacterial activities of RXM and FLRX to P. Aeruginosa was studied by computer image analysis and MTT method. RESULTS: GLX production was reduced significantly by both 1/16 MIC and 1/4 MIC RXM (P < 0.01). 1/16 MIC and 1/4 MIC RXM showed no bactericidal activities to P. Aeruginosa in biofilms, while viable counts in biofilms almost had no difference. However, RXM could enhance the bactericidal activity of FLRX to P. Aeruginosa in biofilms. When FLRX of different concentrations was combined with 1/16 MIC and 1/4 MIC RXM respectively, the difference of the stained BF was counted up by computer image analysis system with significance of P < 0.05 and the viable counts were reduced significantly (P < 0.05). The results was in accordance with SEM pictures. CONCLUSION: RXM has no direct bactericidal activities to P. Aeruginosa in biofilms, but it could inhibit GLX production. It can be considered that RXM could enhance antibacterial activities of FLRX by enhancing the permeability of FLRX into biofilms.

Anti-Bacterial Agents↗
PubMed1999

[Heparin enhances the stimulating effect of thrombopoietin on megakaryocytopoiesis].

OBJECTIVE: To verify whether heparin could enhance the stimulating effect of Tpo on megakaryocytopoiesis. METHODS: Megakaryocytic leukemia cell line M07e, human cord blood CD34+ cells and BALB/c mice were used in this study. The effects of heparin and/or Tpo on megakaryocytopoiesis were studied by [3H]-TdR incorporation assay, CFU-MK plasmic semi-solid culture and in vivo experiment in BALB/c mice. RESULTS: Heparin could enhance the stimulating effect of Tpo on stimulating the proliferation of M-07e, the growth of CFU-MK from human cord blood CD34+ cells and in vivo megakaryocytopoiesis in mice. CONCLUSION: Heparin participates in positive regulation of megakaryocytopoiesis by enhancing the megakaryocytopoietic activities of Tpo.

Animals↗
PubMed1999

[The roles of oxygen free radicals and superoxide dismutase in the inflammatory injury in animal oral mucosa].

OBJECTIVE: To study the roles of oxygen free radicals (OFRs) and superoxide dismutase (SOD) in the inflammatory injury in animal oral mucosa. METHODS: 1. The animal model was established in which an acute oral mucosal inflammation was induced by OFRs. Enzyme histological methods and biochemical methods were used respectively to investigate the activities of some important enzymes such as nicotinamide adenine dinucleotide phosphate-diaphorase and the amount of aminohexoses in the lesions; 2. Electron spin resonance and radioimmunoassay were ultilize respectively to study the effects of exogenous SOD on the amount of OFRs and prostaglandin E2(PGE2) in the lesions. RESULTS: 1. The activities of the enzymes in the oral lesions decreased and the amount of aminohexoses increased significantly; 2. Local administrating SOD could reduce the amount of OFRs and PGE2 in the lesions sufficiently. CONCLUSION: OFRs induced the inflammatory lesion by injuring some important enzymes and connective tissues in the oral mucosa. Local administrating SOD could scavenge OFRs and PGE2 in the oral mucosa sufficiently and reduce the degree of OFRs--induced oral mucosal inflammatory injury.

Animals↗
PubMed1999

[The abnormal expression of pRb during DMBA-induced hamster buccal pouch carcinogenesis].

OBJECTIVE: To study the expression and role of pRb in 7,12-dimethylbenzanthracene(DMBA) induced hamster buccal pouch carcinogenesis. METHODS: DMBA (0.5%) in acetone was applied to the right buccal pouch 3 times per week for up to 12 week. Paraffin-embedded sections were used for pRb immunohistochemical determination (ISAB technipue, polyclonal antibody c-15 for pRb). The density of staining was analysed by rank sum test. RESULTS: The positive staining of pRb was strong in normal buccal epithelium, no alteration of pRb staining in 3 week (hyperplastic epithelium) and somewhat reduced between 6 and 9 week (dysplastic lesion), but it was marked reduced in 12 week (carcinoma). Statistical analysis found that changes of pRb were associated with stages of carcinogenesis. CONCLUSION: These results indicate that abnomal expression of Rb gene product could be related to oral carcinogenesis and may serve as a biomarker for supervising oral malignancy.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1999

[Effect of acupuncture on enzymology of motor neuron of anterior horn of experimental spinal cord injury in rats].

OBJECTIVE: To study the effect of acupuncture on enzymology of the motor neuron of anterior horn of injured spinal cord in rats. METHODS: Chemical staining method was used to quantitatively analyze the acetylcholinesterase (ACHE), succinate dehydrogenase (SDH), acid phosphatase (ACP), changes in motor neuron of anterior horn of spinal cord simultaneously, and auto-analysis photogram apparatus was used to quantitatively analyze. RESULTS: After spinal cord was injured, the AchE and SDH reduced, ACP raised; in the acupuncture group, ACHE and SDH were increased and ACP was lowered after acupuncture (P < 0.05, P < 0.01). CONCLUSION: Acupuncture could regulate enzymology of the motor neuron of anterior horn of injured spinal cord. Acupuncture could inhibit or delay the deterioration of neuron, and also could promote the recovery.

Acetylcholinesterase↗
PubMed1999

[Surgical management of acute retinal necrosis].

OBJECTIVE: To investigate the effects of vitreoretinal surgery in the management of acute retinal necrosis (ARN). METHODS: 17 cases (20 eyes) of ARN had undertaken the surgery, including vitreoretinal surgery for 18 eyes and scleral surgery for 2 eyes. 14 cases (21 eyes) of ARN patients hospitalized at the same period without surgery were used as controls. RESULTS: The follow-up was 5 months to 5 years. 15 eyes in the control group (71.4%) became phthisis bulbi. Useful vision remained in 17 eyes in the surgical group. CONCLUSIONS: Retinal detachment is still a severe complication of ARN, and proper vitreoretinal surgery can improve its prognosis.

Adult↗
PubMed1999

[Establishment of a stochastic model for variation in fecal Schistosoma japonicum egg count and estimation of its parameters].

OBJECTIVE: To establish a stochastic model suitable for interpreting the variation in fecal Schistosoma japonicum egg count, and to estimate its parameters and to describe it. METHODS: Total variation in fecal egg count with a stochastic model can be divided into two kinds of sources, (1) inter-individual variation, and (2) intra-individual variation. Parameters in the model were estimated with the data collected in actual fecal egg count. RESULTS: Parameters M and r differed and k kept nearly the same in various age groups. The best cut-off point of r and M for age-splitting was at eight and 12 years, respectively. Parameter k was assumed the same in different age groups in the model E, and r differed in the groups of 2 - 7 years and 8 years of age, and M differed in the groups of 2 - 11 years and 12 years of age, with a minimum value of Akaike information criterion (AIC). CONCLUSION: Age may be an important factor contributing to the estimations of parameters M and r, and the model E was the best one.

Adolescent↗
PubMed1999

[Studies on male reproductive toxicity caused by hexavalent chromium].

OBJECTIVE: To study male reproductive toxicity caused by hexavalent chromium (Cr(VI +)). METHODS: Morphology of semen and spermatozoa was observed and chromium level in blood, chromium and zinc level in sperm plasma, leuteinizing hormone (LH) and follicle stimulating hormone (FSH) levels in serum were determined for male workers exposed to (Cr(VI +)) (CrO(3)X = 0.0195 mg/m(3)) with occupational epidemiologic investigation and laboratory analysis. RESULTS: For the exposed workers, their seminal counting was (52.21 +/- 45.51) x 10(9)/L, and zinc level in seminal plasma (4,811.85 +/- 1,401.88) micromol/L, significantly lower than those in controls (88.96 +/- 74.82) x 10(9)/L and (5 718.49 +/- 2 827.90) micromol/L, respectively, P < 0.05. Serum FSH was (7.34 +/- 6.88) IU/L in the exposed groups, significantly higher than that of controls (2.41 +/- 1.69) IU/L, P < 0.01. There were no significant difference in semen volume, semen liquefaction time, prevalence of teratospermia, serum Cr(VI +) and LH level in seminal plasma between exposed group and control group (P > 0.05). Prevalence of teratospermia was 0.24 +/- 0.09, and serum LH and FSH were (7.94 +/- 2.67) IU/L and FSH (9.33 +/- 6.47) IU/L, respectively, in workers exposed to high concentration of Cr(VI +) (CrO(3)X = 0.2351 mg/m(3)) significantly higher than those exposed to lower concentration of Cr(VI +) (CrO(3)X = 0.0172 mg/m(3)), with 0.17 +/- 0.06 of prevalence of teratospermia, (5.05 +/- 3.05) IU/L of LH, and (3.74 +/- 3.04) IU/L of FSH, respectively (P < 0.05). CONCLUSION: The results suggested that damage to convoluted seminiferous tubules epithelium, reduction of spermatozoa formation and increase in prevalence of teratospermia could be caused by exposure to certain concentration of Cr(VI +).

Adult↗