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Biomedical subjects

X Sun

Publications and source records attributed to X Sun.

At least 379 records · Page 21Linked to original sources
PubMed1997

[The effect of the expression of BHRF1 gene of EB virus on the proliferation of the cells of nasopharyngeal carcinoma].

In order to learn the effect of the expression of BHRF1 of Epstein-Barr virus on the growth of the cell of nasopharyngeal carcinoma, high BHRF1 expressive vector was set up and transfected in low grade cell line of nasopharyngeal carcinoma, CNE2. Then the cells were cultivated under the condition of insufficient nutrition. The results show that the BHRF1 expression can prohibit the expression of PCNA, and enhance the survival of tumor cells under conditions of nutrition deprivation. So, it suggests that BHRF1 of EB virus could be involved in the development of nasopharyngeal carcinoma.

Cell Division↗
PubMed1997

[Clinical analysis of bilateral neck dissection in patients with laryngeal cancer].

The clinical materials of 54 cases with laryngeal cancer treated between 1980 and 1995 were retrospectively analysed. All patients had received bilateral neck dissection. The results indicated that if one internal jugular vein was preserved, bilateral neck dissection was safe and no fatal complications occur. In this series, most patients were of T3 and T4. The 3 and 5 year survival rates were 62% and 52% respectively. Cervical recurrence was the main reason for the deaths. It is suggested that for patients with advanced supraglottic laryngeal carcinoma, bilateral neck dissections are often needed, functional neck dissection, with preservation of at least one internal jugular vein is the best choice.

Adult↗
PubMed1997

[Comparison of 4 extraction methods of chemical constituents in medicinal tea sishen chaji].

Four extraction method for the medicinal tea Sishen Chaji, were compared with psoralen, schizandrin B and evodiamine taken as indexes. The result shows that the total contents of the three compounds decrease progressively in the following order: semi-bionic extraction, semi-bionic extraction by precipitation with alcohol, extraction with water, and extraction with water and precipitation with alcohol.

Cyclooctanes↗
PubMed1997

[Comparison of two extraction methods for maxingshigan decoction].

The semi-bionic extraction and the extraction with water, two methods for the Maxingshigan Decoction, were compared. The results show that the semi-bionic extraction is superior to the extraction with water in the yield of ephedrine, hydrocyanic acid, glycyrrhetinic acid, calcium ion and extract.

Calcium↗
PubMed1997

[Application of analysis method of orthogonal polynomial regression to sports training].

During studying the dynamic changing rules of athlete's physiological workload in training by means of the polynomial regression method in recent years, we found: (1) If the number of the polynomial term or the order is relatively large (the order number M > 6), the equation's calculating amounts increase greatly and it is easy to have the phenomenon of accession to an "ill state" of the regression matrix or the matrix of the proper equation coefficients as well; (2) Both the accuracy for the fitted results and the stability decrease if there are strong correlation between the different terms in the polynomial (between the different odd power terms or even power terms). In order to overcome these defects we employed the orthogonal polynomial regression method and achieved a better effect.

Exercise Test↗
PubMed1997

[Computer fuzzy control of physiological workload intensity of human body during sports training].

The real-time control of physiological workload intensity of human being during sports training was carried out by means of the Fuzzy Control with the pattern of double input and single output, the Mean of Maximum Method (MOMM) for making fuzzy judgment, the List Method, etc. The fuzzy control system processes the advantages of high-velocity control, small-quantity over modulation and high stability.

Exercise Tolerance↗
PubMed1997

[Effect of loss of consciousness induced by repeated lower body negative pressure on blood-brain barrier permeability in rats].

To investigate the effect of loss of consciousness induced by repeated +Gz on the brain and its mechanism, changes of blood-brain barrier (BBB) permeability and brain water content after repeated lower body negative pressure (LBNP) induced loss of consciousness were observed in 30 rats. Rats were anesthetized and exposed to LBNP (-4.0 kPa). The pressure rapidly returned to control level 2 min after EEG became isoelectric. The BBB permeability was measured using lanthanum trace labeling with electron microscopy and brain water content was determined after one or three LBNP exposures. Most tight junctions among endothelial cells opened through which the lanthanum entered into the neurons and extra cellular space and water content in brain tissues increased significantly (P < 0.05) 1 h after 3 LBNP exposures. It demonstrated that 3 exposures to LBNP induced loss of consciousness can result in an increase of BBB permeability in rats, which may play an important role in the development of G-induced brain edema.

Aerospace Medicine↗
PubMed1997

[Changes of cardiac function during +Gz exposure in rabbits].

Changes of cardiac function was studied during +Gz exposure in rabbits. Seven New Zealand rabbits were anesthetized and exposed to +2, +4, and +6 Gz (each for 30s, onset rate 1G/s, with 15 min interval in between). The left ventricular systolic pressure (LVSP), peak rate of left ventricular pressure rising (+dp/dtmax) and ECG were recorded. The results showed that during +2, +4 and +6 Gz exposures, LVSP decreased by 62.96% (P<0.01), 63.34% (P<0.01) and 82.01% (P<0.01) respectively, and +dp/dtmax decreased by 58.46% (P<0.01), 53.59% (P<0.01) and 63.06% (P<0.01) respectively, and the left ventricular end diastolic pressure decreased by 67.78 % (P>0.05), 332.74 % (P<0.01) and 500.54% (P<0.01) respectively, as compared with those of control. It is suggested that cardiac function is depressed with +Gz exposure.

Acceleration↗
PubMed1997

[Determination of solanesol in the extracts of tobacco leaves by high performance liquid chromatography (HPLC)].

Solanesol, a terpene compound mainly isolated from tobacco, is an important intermediate of medicines such as vitamin K2 and coenzyme Q10. This paper presents an HPLC method for the determination of solanesol in the extracts of tobacco leaves. Solanesol is separated completely on a Zorbax-SIL column, 250 mm x 4.6 mm i.d., by using a mixture of n-hexane, isopropyl ether and ethyl acetate (6:3:1) as mobile phase and determined refractometrically. The isopropyl ether makes the chromatographic peak sharp and the addition of ethyl acetate can prevent the column from blockade during the analysis, and the appropriate temperature (30 degrees C) is beneficial to the shortening of analysis time. This method is fast, accurate and reproducible. It has good linear relationship in the range of 0.2-4 microg. The results have shown that the average recovery is 96.4% and coefficient of variation is 2.8%.

Chromatography, High Pressure Liquid↗
PubMed1997

Reduction of choline acetyltransferase mRNA in the septum of developing rat exposed to inorganic lead.

We previously reported that perinatal exposure to low levels of lead (Pb) results in a pronounced reduction of choline acetyltransferase (ChAT) activity in the septohippocampal pathway of the rat. In the present study we employed a ChAT specific 43-base oligonucleotide hybridization probe to compare the developmental expression of ChAT mRNA and ChAT activity in the septum of normal and Pb-exposed rats. Rats were exposed to Pb via maternal administration of 0.2% solution of Pb acetate in drinking water from one week before birth through postnatal day 21 (PN21). In normal animals, the developmental changes in the ChAT mRNA and activity levels were temporally correlated and approached adult levels by PN21. In the Pb-exposed pups, ChAT mRNA and activity levels were reduced respectively by 69% and 50% at PN7, 47% and 33% at PN14, and 47% and 22% at PN21. In contrast, Pb exposure had no significant effect on either ChAT mRNA or ChAT activity in the dams. These results indicate that cholinotoxicity of Pb in the septohippocampal pathway of the rat involves developmental stage-dependent disruption of ChAT gene expression.

Animals↗
PubMed1997

Measures of endothelial function as an endpoint in hypertension?

The vascular endothelial cell is a multipotent cell which has several functions: transport barrier, phagocytosis, coagulation/anticoagulation, fibrinolysis, autocrine/paracrine and metabolic functions. The release of vasoactive agents, such as the vasodilators EDRF (NO) and EDHF, and vasoconstrictors, such as endothelin (ET), represents an important local mechanism altering the balance of vasodilation/ vasoconstriction of the vascular smooth muscle cell. Inhibition of the synthesis of NO by exogenous (e.g. L-NAME) or endogenous (e.g. ADMA) L-arginine analogues may cause transient or sustained hypertension. A similar effect may be achieved by continuous administration of the potent vasoconstrictor ET. Endothelial dysfunction, associated with a deficient NO production and release as well an enhanced ET generation, may be present in some forms of vascular disease, such as hypertension, atherosclerosis, diabetes mellitus or sleep apnea. Whether such alterations may be a cause of hypertension and involved in the maintenance of high blood pressure or whether they represent a consequence of the hypertensive disease remains to be concluded. Furthermore, while there is emerging evidence that endothelial dysfunction in cardiovascular disease may be reversed by therapy, it remains to be determined whether measures of endothelial function in man may serve as predictors for morbidity or mortality.

Endothelium, Vascular↗
PubMed1997

[Cellular adhesion molecule (CD44) in ovarian tumors].

OBJECTIVE: To investigate a method of detecting adhesion molecule (CD44) contents in ovarian tumors and its clinical significance. METHODS: In 106 patients with ovarian tumors (50 benign and 56 malignant), the adhesion molecule (CD44) contents in peripheral blood lymphocytes (PBL) and in neoplastic tissues were analysed (quantitatively by using flow cytometric-immunological method). RESULT: (1) The CD44 contents in the PBL of the patients with malignant tumor were obviously higher than those of patients with benign tumors (P<0.05) and than those of the control (P < 0.01); (2) Within the group of patients with malignant tumors, the CD44 contents in the neoplastic tissues were higher than those in the PBL (0.01 < P < 0.05); There was no significant difference in CD44 contents among the different histopathological types, whether benign or malignant; (4) The CD44 contents in the PBL decreased gradually after surgery. CONCLUSION: To analyse the CD44 contents in PBL and neoplastic tissues by flow cytometry may be an important method or parameter to differentiate benign ovarian tumors from malignant tumors and to discover recurrence of metastasis of malignant tumors in early stage.

Cell Adhesion Molecules↗
PubMed1997

Genital Ureaplasma urealyticum infection in varicocele-related infertility.

OBJECTIVE: To assess the existence of a possible infectious factor in varicocele-related infertility. METHODS: A total of 925 seminal plasmas from 590 infertile men with varicocele and 335 infertile patients without palpable varicocele were cultured for Ureaplasma urealyticum infection, and routine semen analysis was made. RESULTS: The infection rate of Ureaplasma urealyticum in seminal plasmas was 48.22%. The asymptomatic genital infection of Ureaplasma urealyticum was traced in 329 (55.76%) varicocele men and 117 (34.93%) infertile patients without varicocele (control group). A significant quantitative difference in the incidence of genital Ureaplasma urealyticum infection between the varicocele and control group was observed (P < 0.005) and asthenozoospermia was significantly more prevalent in the patients with varicocele than in the other patients (P < 0.05). CONCLUSIONS: Genital Ureaplasma urealyticum infection may play a role in varicocele-related infertility. To prevent future infertility, men with both varicocele and genital Ureaplasma urealyticum infection may benefit from early evaluation and treatment.

Adult↗
PubMed1996

Nitric oxide stimulates both the basal and reflex release of vasopressin in anesthetized rats.

In view of the fact of the high concentration of neuronal nitric oxide synthase (NOS) in the supraoptic and paraventricular nuclei as well as the posterior pituitary, it has been supposed that nitric oxide (NO) may be involved in the regulation of hormone secretion from these sites. In the present study, L-arginine, the precursor of NO, and N(omega)-nitro-L-arginine methyl ester (L-NAME), the NOS inhibitor, were intracerebroventricularly (i.c.v.) administered into the pentobarbital anesthetized rats. The results showed that plasma arginine vasopressin (AVP) concentration increased after the injection of L-arginine (1.0 mg in microliters, i.c.v.) and decreased after the L-NAME (270 micrograms in 5 microliters, i.c.v.). The elevated plasma AVP level in response to short-term hypotension induced by intravenous infusion of sodium nitroprusside was also significantly reduced by i.c.v. administration of L-NAME. The results indicate that NO acts as a stimulating factor to both the basal and reflex release of AVP, opposing the view that NO plays an inhibitory role in the regulation of AVP secretion.

Anesthesia↗
PubMed1996

Inhibition of the mitochondrial KATP channel by long-chain acyl-CoA esters and activation by guanine nucleotides.

The mitochondrial KATP channel (mitoKATP) is highly sensitive to ATP, which inhibits K+ flux with K1/2 values of 20-40 microM. This raises the question, how can mitoKATP be opened in the presence of physiological concentrations of ATP? We measured K+ flux in liposomes reconstituted with purified mitoKATP and found that guanine nucleotides are potent activators of this channel. ATP-inhibited K+ flux was completely reactivated by both GTP (K1/2 = 7 microM) and GDP (K1/2 = 140 microM). These ligands had no effect in the absence of ATP. The K1/2 for ATP inhibition exhibited quadratic dependence on [GTP] and [GDP], consistent with two binding sites for guanine nucleotides. We also found that palmitoyl-CoA and oleoyl-CoA inhibited K+ flux through reconstituted mitoKATP with K1/2 values of 260 nM and 80 nM, respectively. This inhibition was reversed by GTP (K1/2 = 232 microM) as well as by the K+ channel openers cromakalim (20 microM) and diazoxide (10 microM). Inhibition of mitoKATP by long-chain acyl-CoA esters, like that of ATP, exhibited an absolute requirement for Mg2+ ions. We propose that the open-closed state of the mitochondrial KATP channel is determined by the relative cytosolic concentrations of GTP and long-chain acyl-CoA esters.

Acyl Coenzyme A↗
PubMed1996

Calcium in suramin-induced rat sensory neuron toxicity in vitro.

Suramin is an experimental chemotherapeutic agent and a neurotoxin which causes a dose-dependent peripheral neuropathy in vivo and inhibits dorsal root ganglion (DRG) neurite outgrowth in vitro. The mechanism of suramin-induced cyto- and neurotoxicity remains unclear. Calcium is a key signal transducer in cellular responses to a variety of physiological and pathogenic stimuli. In the present study, we have determined the role of calcium in suramin-induced neurotoxicity in dorsal root ganglion neurons in vitro. Suramin-induced inhibition of neurite outgrowth and induction of neuronal cell death were dose-related phenomena. A low level of extracellular calcium significantly reduced suramin-induced inhibition of neurite outgrowth and delayed neuronal cell death in vitro. Nimodipine (100 microM), an L-type voltage-sensitive calcium channel (VSCC) inhibitor, mimicked low calcium medium and protected neurite outgrowth in regular calcium medium supplemented with 300 microM suramin. TMB-8 (100 microM), an inhibitor of intracellular calcium release, failed to protect neurite outgrowth against the toxin. Calmidazolium (10 microM), a potent calmodulin inhibitor, and calpain inhibitor peptide (CIP, 10 microM) protected neurite outgrowth against suramin. The results support the hypothesis that the calcium signaling system is important in suramin-induced neurotoxicity. Influx of extracellular calcium is more important than release of intracellular calcium in causing cell injury in vitro.

Animals↗