Biomedical subjects

X Zeng

Publications and source records attributed to X Zeng.

At least 181 records · Page 10Linked to original sources

PubMed1997

[Artificial neural network applied for spectral overlap interference correction in ICP-AES].

A back-propagation artificial neural network (BP-ANN) has been applied to correcting spectral overlap interference in inductively coupled plasma atomic emission spectrometry (ICP-AES). Some network parameters including the range of input values and training sequence for training patterns presented to the network were discussed using simulated Ce 413.380nm and Pr 413.380nm line profiles. Results show that the noise in simulated mixture spectra will slow down the network convergence and has more influence on network prediction.

Neural Networks, Computer↗

PubMed1997

Experimental study on relationship between exogenous estrogen and breast cancer risk.

OBJECTIVE: To investigate the relationship between exogenous estrogen and breast cancer risk. METHODS: Female rats were randomly divided into three groups, namely diethylstilbestrol (DES), norethindrone compositae (CoNET) and control group. The histological structure and ultrastructural changes of mammae were observed. The levels of sexual hormones in serum were determined and the AgNOR counts, DNA contents and steroid receptor contents in mammary epithelium were also detected. RESULTS: In DES group, the level of progesterone (10.38 ng/ml) was obviously lower than that in the control group (13.37 ng/ml); the incidence of hyperplasia of mammary gland (73.33%) was significantly higher than that in the control group (7.69%); and the degree of hyperplasia was obviously more serious than that in the control group. Moreover, there were 13.33% of rats with atypical hyperplasia in DES group. The DNA contents, AgNOR counts and estrogen receptor (ER) positive rate were markedly higher in DES group (95.60, 2.43 and 71.71% respectively) than in the control group (83.07, 1.88 and 40% respectively). However, in CoNET group, there were no obvious influences on ER, AgNOR and DNA in mammary epithelium. CONCLUSIONS: Exogenous estrogen (DES) could affect the levels of sexual hormones in serum, accelerate the DNA duplication, increase the AgNOR counts and ER contents, and induce atypical hyperplasia and ultrastructural changes of mammary gland, hence becoming a latent risk factor of breast cancer. However, the results failed to suggest that the contraceptive, CoNET, could increase the risk of breast cancer.

Animals↗

PubMed1997

[A study on the setting-up a high-risk scoring system for neonatal adverse outcomes].

In order to popularize the technique of risk approach to neonates among child health care providers in rural areas, data of surveillance for risk factors of the three major adverse outcomes in 1,116 neonates in rural areas of Zhangye prefecture, Gansu Province, China were analyzed, and two comprehensive scoring method of "whole risk factors" and "significant risk factors", to identify neonates at high-risk, were established and compared with standardized partial coefficient weighting of multiple logistic regression. The "whole risk factors" method of comprehensive scoring is recommended by this study as criteria for identification of high-risk neonates.

Female↗

PubMed1997

[The protective effect of captopril on the ischemic myocardium in dogs through coronary sinus retroperfusion].

The protective effect of coronary sinus retroperfusion of Captopril on the ischemic myocardium was observed in dogs with acute myocardial infarction (AMI). The results showed that the infarction size and the level of coronary sinus plasma endothelin (ET) and manodialdenyde (MDA) were smaller and lower when Captopril was administered by coronary sinus retroperfusion than that by systemic intravenous injection. These results suggest that (1) Captopril can be distributed adequately in the local ischemic myocardial zones when administered by coronary sinus retroperfusion in the presence of coronary artery occlusion, (2) Captopril can more effectively protect ischemic myocardium by inhibition of the ET release and against the oxygen free radicals in ischemic myocardial area when used by coronary sinus retroperfusion.

Animals↗

PubMed1996

[Chemical constituents of the fruits of Vitex trifolia L].

Five compounds were isolated from the fruits of Vitex trifolia and identified on the basis of spectral data and chemical methods to be rho-hydroxybenzoic acid, beta-sitosterol, beta-sitosterol-3-O-glucoside, casticin and, 3,6,7-trimethylquercetagetin. Except beta-sitosterol all of the compounds were obtained from the fruits of the plant for the first time.

Drugs, Chinese Herbal↗

PubMed1996

[The effects of a single active ingredient (T4) of Tripterygium Wilfordii Hook on the production of tumor necrosis factor by the peripheral blood mononuclear cells and synovium cells of rheumatoid arthritis patients].

Encouraged by good therapeutic results of the semipurified preparations of Tripterygium Wilfordii Hook (TWH) (code name T4) a single-active ingredient of TWH with the code name of T4 was obtained. The in vitro effects of T4 on the bioactivity of TNF produced by PBMC of normal subjects (n = 10) and RA patients (n = 6) or the RA digested synovium single cells (DSSC) were studied. The results showed that under pretreatment of PBMC of healthy persons with T4 (35 ng/ml) for two hours, TNF were reduced to 36.13 +/- 1.75% in comparison with the control of 63.33 +/- 2.51% (P < 0.001), with an inhibition rate of 40.31%. Similarly, the inhibition rate for the PBMC of RA patients (P < 0.001), was 25.54%. The fact that coculture of PBMC and T4 for 6 hours instead of treatment with T4 for 2 hours caused an inhibition rate of 40.51% (P < 0.01), might indicate that time of interaction was also a factor of importance. T4 also reduced TNF secretion by RA-DSSC from 72.1 +/- 6.1% to 51.6 +/- 2.0% with an inhibition rate of 28.4%. The aformentioned indicates that T4 appears to possess suppressive actions on production of TNF by PBMC and DSSC of RA patients. Therefore, it is possible that T4 may be used clinically for RA patients.

Adult↗

PubMed1996

[Dental appliances for the treatment of obstructive sleep apnea syndrome].

This study combined the use of cephalometrics and overnight polysomnographic monitoring to analyze the effects of a dental appliance on airway, sleep and respiratory conditions in 10 patients with obstructive sleep apnea. The findings indicated that horizontal and vertical mean changes in mandibular position while the appliance was worn were 1.73 mm and 9.30 mm, respectively, the mean superior airway space increased by 2.80 mm (P < 0.01), while the mean middle airway space increased by 6.75 mm (P = 0.01), the inferior airway space, however, didn't change significantly when the appliance was worn. The average Apnea Index decreased by 15.98 events per hour when the appliance was worn (P < 0.01), the average Respiratory Disturbance Index decreased from 39.43 to 6.62 events per hour in 9 of 10 patients (P < 0.01, one patient didn't have recording of hypoventilation). the lowest SaO2 value increased from 73.87% to 85.50% (P < 0.01). The reduction in the rate of airway obstructive events is attributed to the effect of appliance on the orophargneal structures. The dental appliance is a conservative, successful treatment alternative that could benefit patients with obstructive sleep apnea syndrome.

Aged↗

PubMed1996

[The clinical efficacy of hepatic artery infusion chemotherapy and chemoembolization in the treatment of liver metastases].

The efficacy and clinical experience of transcatheter hepatic artery infusion chemotherapy alone or chemoembolization in 118 patients with hepatic metastases were reviewed. Hepatic arterial infusion chemotherapy followed by embolization with lipiodol suspension and gelatin sponge pieces was carried out in 72 cases, infusion chemotherapy followed by embolization with lipiodol suspension in 32, and arterial infusion chemotherapy alone in 14. The results showed that the clinical efficacy of the first method was the best while that of the third method was the worst. The best effect was seen in patients with the single and hypervascular metastatic focus. The overall survival rate was 86.0%, 25.0%, 3.0% in 1 year, 3 years and 5 years, respectively.

Antineoplastic Agents↗

PubMed1996

[Inhibitory effect of tamoxifen on the breast cancer risk induced by exogenous estrogen in rat].

In order to investigate the inhibitory effect of tamoxifen (TAM) on breast cancer risk induced by exogenous estrogen, female rats were randomly allocated into three groups, namely DES (diethylstilbestrol) group, DES + TAM group and blank control group. We found that in DES + TAM group the levels of estradiol (62.14 pg/ml) and progesteron (15.02 ng/ml) in serum were obviously higher than those in DES group (52.69 pg/ml, 10.38 ng/ml) individually (P < 0.05, P < 0.01), the incidence (28.57%) of mammary hyperplasia was significantly lower than that in DES group (73.33%) (P < 0.025), the degree of hyperplasia markedly slighter than that in DES group (P < 0.025), and the AgNOR count (1.93%), DNA content (80.24%) and ER positive rate (36.46%) were obviously lower than those in DES group (2.43%, 95.60%, 71.71%) individually. The results indicated that TAM could increase the levels of estradiol and progesterone in serum, also could decrease the ER contents, AgNOR counts and DNA contents in mammary epithelium. It suggested that the TAM could interfere the effect on the breast carcinogenesis induced by exogenous estrogen.

Animals↗

PubMed1996

[The diagnosis and surgical management of ectopic thyroid tumour].

The diagnosis and treatment of seven patients with ectopic thyroid tumour in different position suggest that fine needle aspiration biopsy cytology be used before operation and fast freezing section be made during operation. Isotope scanning should be used as a routine method to determine whether there is normal thyroid in neck, so that we can treat it appropriately and prevent serious complications after operation.

Adenocarcinoma↗

PubMed1996

[Study of electrophysiological properties of large conductance K(+)-channels in outer hair cells from the guinea pig with patch-clamp technique].

The basic electrophysiological characteristics of large conductance K(+)-channels in the basolateral cell membrane of outer hair cells (OHC) from the guinea pig cochlea were studied with patch-clamp technique. Acutely isolated OHC preparations were obtained by enzymatic digestion and excised patches were made in cell-attached configuration to record single-channel currents led by patch-clamp micropipette and fed to patch-clamp amplifier. Data were sampled and analyzed on-line with a computer. The result showed that the typical properties of single channels of large conductance K(+)-channels were: 1. The channel was activated by depolarization of membrane and it showed a marked voltage-dependence. The channel had a unitary conductance of about 133 pS and the channel current reversed at about -30mV under asymmetrical K+ concentration gradient. 2. Tetraethylammonium (TEA, > 10 mmol/L), a potassium channel blocker, dose-dependently abolished the outward current. 3. The open probability (Po) and mean open time of this channel was markedly increased with elevation of cytoplasmic Ca2+ concentration. These results suggest that a population of voltage-dependent and Ca(2+)-activated K+ channel exists in the basolateral membrane of OHC of the guinea pig; it is characterized by a very high unitary conductance and high sensitivity to Ca2+ and is blocked by K+ channel blocker. This work provided valuable basic materials for further study on the regulation and drug influence of the type of single channels.

Animals↗

PubMed1996

[A cohort study on the relationship between standardized mortality of pulmonary heart disease and smoking].

We explored the relationship between the standardized mortality of pulmonary heart disease (PHD) and smoking at Shifang county through a five-year follow-up study of 29,498 farmers over 35 years old. The death ratio of PHD was 30.35%, which stood first in all causes of death. The mortality of PHD for cigar/cigarette smokers regardless of sex was not significantly different from that for nonsmokers (P > 0.05). The RR was 1 or so. The analysis of data stratified by age showed that the specific mortality increased with age in spite of some inequalities smoking; the RR of PHD for cigar/cigarette smokers in all age groups were 1 or so revealing no significant differences (P > 0.05). However, the standardized mortality of PHD increased with the accumulated amount of smoking. The relationship between the mortality of PHD and short-term smoking with small dose was not significant (P > 0.05), but when the accumulated amount reached certain level, i.e. the smoker consumed cigar more than 270 kg or consumed cigarette more than 20,000 packs, the relationship between the behavior of cigar/cigarette smoking and the mortality of PHD became apparent. The RRs were 1.40-3.94 and the ARs 171-1610 per 100,000 person years (P < 0.05-0.01).

Adult↗

PubMed1996

[Anorectal malignant melanoma: report of 33 cases].

33 Cases of anorectal malignant melanoma (ARMM) diagnosed pathologically were treated in Tianjin Cancer Hospital from 1996 to 1994. Some of these patients were treated with abdominoperineal resection (Mile's operation) and local resection plus chemotherapy, biotherapy and radiotherapy, others were given chemotherapy only. 25 cases were followed up from six months up to six years. The results showed that the median survival time was 23.5 months in the group of Mile's, 17.5 months of local resection and 5.5 months in chemotherapy alone respectively. The authors considered that early diagnosis and treatment are the key to raise the survival rate. For the cases diagnosed pathologically the Mile's operation should be performed and groin dissection is necessary for cases of groin lymphatic metastasis.

Adult↗

PubMed1996

[A review of 10 patients of nephrectomy through laparoscope video].

Ten patients were subjected to nephrectomy through laparoscope video. Compared with routine nephrectomy, it has such merits as slight trauma, less bleeding and pain during the operation as well as quick recovery and short hospitalization. In 6 male patients and 4 female patients the oldest one was 75 years old, and the youngest one was 15 years old. Seven patients suffered from nephrohydrosis and 3 from polycystic kidney. Before the operation, the patients were found the loss of function of the diseased kidney. The video scope was inserted into the abdominal cavity through an operating hole under the navel making the exploration in the cavity; the other operations are as basical as routine operations. The ill kidney was cut off and put into a special pocket, then it was cut into pieces, and taken out. The abdominal membrane was enclosed by the emanometer, the drainage tube kept. In the 10 patients the operations were successful and satisfactory.

Adolescent↗

PubMed1996

[Cloning and identification of the Mycobacterium bovis BCG gene for signal peptide of antigen 85-B].

OBJECTIVE: To clone and identify the Mycobacterium bovis BCG gene for signal peptide of antigen 85-B. METHODS: Using a polymerase chain reaction technique, the signal peptide sequence (position 94 to 211) of antigen 85-B was technique, which is one of the major protein secreted by Mycobacterium bovis BCG (Bacille-Calmette-Guerin). The gene of 117bp fragment was cloned into the SacI and EcoRI sites of pBluecript SK, and its sequence was determined by using T7DNA polymerase kit. RESULTS: The sequence analysis showed that the sequence of 117bp signal peptide was not misincorporated and in 3' end understream of signal peptide the 12 multi cloning sites for foreign gene could be provided by the recombinant plasmid. CONCLUSIONS: The signal sequence of BCG antigen 85-B was cloned into the pBluescript plasmid. The recombinant plasmid was called BCG-S01. According to the genetic information a secreted protein from M. bovis BCG could be utilized in making a useful vaccine vehicle to produce and secrete a vaccinal protein from M. bovis BCG living cells.

Antigens, Bacterial↗

PubMed1995

Yeast two-hybrid system demonstrates that estrogen receptor dimerization is ligand-dependent in vivo.

Previous studies using in vitro procedures have not clearly established whether the estrogen receptor (ER) acts as a monomer or dimer in the cell. We have used the yeast two-hybrid system as an in vivo approach to investigate the dimerization of the estrogen receptor in the absence and presence of estrogen and anti-estrogens. This system is independent of ER binding to the estrogen response element. Two vectors, expressing GAL4 DNA binding domain-human ER and GAL4 transactivation domain-human ER, were constructed. Control experiments showed that each fusion protein had a high affinity binding site for estradiol-17 beta and could transactivate an ERE-LacZ reporter gene in yeast similar to the wild type ER. The two fusion proteins, GAL4 DB-hER and GAL 4 TA-hER, were expressed in the yeast strain, PCY2, which carries a GAL1 promoter-lacZ reporter. ER dimerization was measured via reconstitution of GAL4 through interaction of the fusion proteins, which transactivates LacZ through the GAL1 promoter. When both ER fusion proteins were expressed, beta-galactosidase activity was estradiol-17 beta-inducible. Furthermore, we showed that both tamoxifen and ICI 182,780 also induced beta-galactosidase activity, albeit lower than that induced by estradiol-17 beta. These results strongly argue that ER dimerization is ligand-dependent and the dimer can be induced by estradiol-17 beta, tamoxifen, or ICI 182,780. We also treated the yeast containing the two fusion proteins with estradiol-17 beta and tamoxifen or ICI 182,780 simultaneously to determine the effects on ER dimerization. beta-Galactosidase activity was lower when the yeast was treated with a higher ratio of tamoxifen or ICI 182,780 to estrogen than estradiol-17 beta alone. Taken together, we conclude that ER dimerization is ligand (estradiol-17 beta, tamoxifen, or ICI 182, 780)-dependent, and we suggest that estradiol-17 beta-induced dimers are destabilized when estradiol-17 beta is used with tamoxifen or ICI 182,780 simultaneously.

Base Sequence↗

PubMed1995

Double-stranded damage of DNA.RNA hybrids by neocarzinostatin chromophore: selective C-1' chemistry on the RNA strand.

Glutathione-activated neocarzinostatin chromophore generates bistranded lesions in the hybrid formed by yeast tRNA(phe) and DNA complementary to its 31-mer 3' terminus. To elucidate the chemistry of the RNA cleavage reaction and to show that the lesions are double-stranded (ds), a series of shorter oligoribonucleotides containing the target sequence r(AGAAUUC).(GAATTCT) (underlining indicates major attack site) was studied as substrates. In addition to cleavage at both U residues, major damage was produced in the form of an abasic site at the U residues. Evidence for abasic site formation on the RNA strand was obtained from sequencing-gel analysis and measurement of uracil base release. Initial evidence for the ds nature of the damage came from experiments in which 2'-O-methyluridine was substituted for uridine in the RNA at one or both of the target sites. The site containing the substitution was not a target for cleavage or abasic site formation, and the particular T residue, staggered two nucleotides in the 3' direction on the complementary DNA strand, was cleaved significantly less. These studies were valuable in identifying the DNA ds partner of the RNA attack site. Direct evidence for ds lesions came from analysis of the products from a hairpin oligonucleotide construct in which the RNA and DNA strands were linked by four T residues and contained an internal 32P label at the 3' end of the RNA strand. Substitution of deuterium for hydrogen at the C-1' position of the U residues led to a substantial isotope effect (k1H/k2H = 3) upon the formation of the RNA abasic lesion and the RNA cleavage products, providing conclusive evidence for selective 1' chemistry. On the other hand, cleavage at the T residues on the complementary DNA strand involved C-5' hydrogen abstraction, as was also true for the T residue in an oligodeoxynucleotide analogue of the RNA strand. Chemical mechanisms to account for the RNA cleavage and abasic site formation via C-1' hydrogen abstraction are proposed.

Antibiotics, Antineoplastic↗

PubMed1995

Reduction of GABA-mediated inhibitory postsynaptic potentials in hippocampal CA1 pyramidal neurons following oral flurazepam administration.

Oral administration of the benzodiazepine, flurazepam, for one week results in tolerance in vivo and in vitro and in a reduction in recurrent and feedforward inhibition in vitro in the CA1 pyramidal cell region of hippocampus. In the present study CA1 pyramidal cells were examined intracellularly in vitro in rat hippocampal slices (500 microns) from rats sacrificed two or seven days after cessation of oral flurazepam treatment. Following drug treatment, the membrane characteristics of CA1 pyramidal cells were not significantly different from control neurons. GABAA-mediated, early inhibitory postsynaptic potentials were significantly reduced in amplitude (60%) in pyramidal neurons from rats killed two days, but not in those killed seven days, after the end of drug administration. The decrease in early inhibitory postsynaptic potential amplitude was observed using just-subthreshold, threshold and supramaximal orthodromic stimulation as well as following antidromic activation. The magnitude of the decrease in the early inhibitory postsynaptic potential amplitude was similar in the presence of the GABAB antagonist, CGP 35348, and could not be attributed to differences in the strength of afferent stimulation between flurazepam-treated and control groups. The size of the GABAB-mediated, late inhibitory postsynaptic potentials was also significantly decreased (45%) in comparison to control cells. Reversal potentials for both the early (-72 mV) and late (-92 mV) hyperpolarizations were not significantly different between groups. Following high intensity orthodromic stimulation, in the presence of an intracellular sodium channel blocker (QX-314) which also blocks the GABAB-mediated late hyperpolarization, a bicuculline-sensitive late depolarizing potential was unmasked in neurons from FZP-treated rats, but never from control cells. Excitatory postsynaptic potential amplitude was significantly increased in flurazepam-treated neurons and the threshold for the synaptically-evoked action potential was significantly increased. Following depolarizing current injection, the duration and frequency of pyramidal cell discharges and the action potential threshold were not altered by oral flurazepam treatment. The amplitude of the fast afterhyperpolarization was also not changed. Overall, the findings indicate an impairment of transmission at GABAergic synapses onto hippocampal CA1 pyramidal cell neurons after chronic benzodiazepine treatment at a time when rats are tolerant to the anticonvulsant effects of the benzodiazepines in vivo.

Acetates↗