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Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 1,135 records · Page 63Linked to original sources
PubMed1996

Immunodetection of beet necrotic yellow vein virus RNA3-encoded protein in different host plants and tissues.

The protein p25 open reading frame (ORF) of beet necrotic yellow vein virus-BNYVV RNA3 was cloned into bacterial expression vector downstream of the 5-'terminus part of beta-galactosidase ORF and the expressed p25 fusion protein was used to produce an antiserum. The latter was employed to detect the subcellular location of p25 in mechanically inoculated Tetragonia expansa, Chenopodium quinoa and sugarbeet leaves by Western blot assay. The results showed that p25 was present as a soluble protein only in the S30 fraction of T. expansa, C. quinoa and sugarbeet leaves infected with BNYVV.

Animals↗
PubMed1996

The long-term suppressive effect of prior activation of synaptic inputs by low-frequency stimulation on induction of long-term potentiation in CA1 neurons of guinea pig hippocampal slices.

We have investigated the effects of prior activation of afferent inputs by a train of low-frequency stimulation (LFS) on the induction of long-term potentiation (LTP) induced by high-frequency stimulation (tetanus, 100 Hz, 100 pulses) in CA1 neurons of guinea pig hippocampal slices. The parameters of the LFS were altered systematically: the frequency (1 or 5 Hz); the number of pulses (80, 200 or 1000); and the time lag from the LFS to the tetanus (20, 60 or 100 min). Conditioning effects of the LFS on the induction of LTP were evaluated in terms of the slope of the field excitatory postsynaptic potential (S-EPSP) and the amplitude of the population spike (A-PS). LTP could reliably be induced by 100 Hz tetanic stimulation delivered to a naive slice. In contrast, the attempt to induce LTP 60 min after LFS of 200 or 1000 pulses at 1 Hz resulted only in short-term potentiation while the LFS itself produced no significant change in the responses. The suppressive effect on LTP was significantly reduced for 1 Hz LFS with a smaller number of pulses (80 pulses), or a shorter (20 min) or longer (100 min) time lag from the LFS to the tetanus, or with LFS at a higher frequency (5 Hz). When the LFS of 1000 pulses at 1 Hz was delivered in the presence of the N-methyl-D-aspartate (NMDA) receptor antagonist AP5 (D,L-4-amino-5-phosphonovalerate, 50 microM), which was washed out after the end of the LFS, the tetanus given 60 min after application of the LFS produced stable LTP, indicating the involvement of NMDA receptor/channels in the mechanisms of this particular form of synaptic plasticity-long-term suppression of LTP.

2-Amino-5-phosphonovalerate↗
PubMed1996

[The establishment of a three dimensional PCR screening system and quality evaluation of human YAC library].

In order to screen out YAC clones in the CEPH YAC library related to a definite gene, DNA fragment or locus, we need to establish a screening system. This paper includes the establishment of this system and the evaluation of its feasibility. According to the experiments, we suggest that it is better to screen the Mega YAC part of the library at first and put five culture plates as a group. Meanwhile, FISH experiments to assess the quality of CEPH YAC library and the first generation physical map of human genome, Were conducted FISH experiments on 26 YAC clones were carried out. There were 13 clones that were chimeric (about 50%), 6 clones that were mapped by mistake (about 23%). So, there were only 9 clones that were mapped correctly and were not chimeric (about 35%).

Chromosomes, Artificial, Yeast↗
PubMed1996

Studies on high-density cultivation of Vero cells with biosilon solid microcarrier.

From eight kinds of microcarriers, Biosilon has been chosen as the most suitable microcarrier for high-density cultivation of African green monkey kidney (Vero) cells. Conditions affecting high-density cultivation were studied with a 500 ml modified Wheaton spinner flask. When cultivation with a 1.5 L CelliGen bioreactor at inoculum density of 4.9 x 10(6)/ml and perfusion volume increased from 0.20 L to 3.65 L gradually, the cell density could reach 2.05 x 10(7)/ml after 22 days of cultivation. When Vesicular Stomatitis Virus (VSV) was inoculated into the cultures of 1.21 x 10(6) ml at the some MOI (multiplicity of infection), the virus titers reached 7 log TCID50/ml and 8 log TCID50/ml, respectively.

Animals↗
PubMed1996

[Detection of nicotine in prehistorical skeletal remains of South China].

Human remains from excavation sites in southern China, dated from 100 to 10,000 years, were investigated for nicotine. The nicotine concentrations were measured by radioimmunoassay. Consequently, the values measured represent the sum of nicotine and its metabolites. Positive results were observed in 25.9% (mean values of all samples). The concentrations ranged from 11.8 to 474.2 ng/g sample. From the excavation sites with the highest number of individuals, Chongtong (18 individuals) were 38.9%, and from the site Leigund (21 individuals) were 28.6% from the samples nicotine positive. The highest level with 474.2 ng/g nicotine was found in a sample dated 100 years. It is possible, that this individual was smoker. In addition the samples were investigated also by gas chromatography/mass spectrometry. The GC/MS indicated the presence of nicotine and its primary metabolite, cotinine. The presence of cotinine points out the assumption that nicotine was used antemortem. The detection of unchanged nicotine indicates that nicotine remained present in bones up centuries.

Bone and Bones↗
PubMed1996

Study on serum-free media for genetically engineered CHO cells producing prourokinase.

Based on the initial optimization of DMEM:F12(1:1), two kinds of serum-free media, 11G-SG-SFM and 11G-SE-SFM, were formulated by using orthogonal experiments for the growth of genetically engineered CHO cell line 11G and the production of recombinant prourokinase (pro-UK) in a suspension culture, respectively. Growth of 11G cells in 11G-SG-SFM was comparable with that observed in DMEM:F12 + 5% NBS and CHO-S-SFM. 11G cells grew slowly in 11G-SE-SFM, but secreted a relatively high level of pro-UK. The pro-UK productivity of 11G cells in 11G cells in 11G-SE-SFM reached 800 to 1,000 IU/10(6). d-1 and was about 80% and 20% higher than in DMEM:F12 + 5% NBS and CHO-S-SFM, respectively.

Animals↗
PubMed1996

Emergency percutaneous transluminal coronary angioplasty in acute myocardial infarction complicated with cardiogenic shock.

OBJECTIVE: To approach the efficacy of emergency percutaneous transluminal coronary angioplasty (PTCA) in Chinese patients with acute myocardial infarction (MI) complicated by cardiogenic shock. METHODS: Twelve patients with cardiogenic shock treated by emergency PTCA in this institution from January 1990 to May 1994 were retrospectively reviewed. There were anterio-lateral MI in 4 cases, inferio-posterial MI in 7, anterial and inferial MI in I, of which triple vessel disease in 4 cases, double vessel disease in 6, single vessel disease in I and left main coronary artery (LM) disease in 1. PTCA was performed under assistance of IABP in 7 cases and of centrifugal pump in 1. Only infarct-related Coronary artery (IRCA) was dilated during acute phase. Direct PTCA was done in 7 cases and rescue PTCA after failure of thrombolytic therapy in 5. RESULTS: PTCA was successful in 11 (91.7%) of the 12 cases, in 1 case with failure of PTCA the IRCA was reperfused by intracoronary thrombolytic therapy. Cardiogenic shock was reverted in 7 (63.6%) of the 11 cases reperfused by PTCA, among whom 6 (54.5%) survived. Four died of irreversible shock after 3 hours-9 days and 1 case with reversed shock died of cardiac rupture after 4 days. During a period of 13-55 months follow-up, long-term survivals were obtained in 4 cases. CONCLUSIONS: Emergency PTCA can achieve a high success rate and significantly decrease the mortality rate to less than 50% in Chinese patients with acute MI complicated with cardiogenic shock. The patients tolerate the PTCA procedure very well under the assistance of intra-aortic balloon counterpulsation (IABP) even in very severe condition.

Aged↗
PubMed1996

Re-evaluation of the mechanism and treatment of angina decubitus.

30 patients with angina decubitus (AD) were studied during hospitalization. These patients were found to have severe coronary artery obstructive lesions and an increase of myocardial oxygen consumption (MOC) before the onset to AD, indicating that AD belongs to the category of effort angina. 18 patients were investigated by continuous hemodynamic monitoring. Three patients had significant increase in pulmonary artery diastolic pressure (PADP) before the onset. In the other 15 patients, PADP increased slightly in 12 and remained unchanged in 3 cases before the onset. Left ventriculography showed ejection fraction (EF) > 45% in 25 of the 27 patients. These results indicate that left ventricular (LV) systolic dysfunction is not a major factor in the pathogenesis of AD. The patients with LVEDP > 12 mmHg constituted 60% of 25 patients with EF > 45%, suggesting that these patients had obvious LV diastolic dysfunction, which may be the major factor in the pathogenesis of AD. According to the results of our treatment, beta blockers may be used as the major form of treatment in the patients with AD.

Adult↗
PubMed1996

[Chemical constituents of Taxus yunnanensis Cheng et L. K. Fu].

Five compounds were isolated from the bark of Taxus yunnanensis. Their structures were identified on the basis of spectral analysis and physico-chemical constants as taxol C-7-xylose, taxol B, 10-deacetyl baccatin III, taxusin and 2R,3R-catechin.

Antineoplastic Agents, Phytogenic↗
PubMed1996

[The PCR amplification, cloning, sequencing, expression in E. coli of gene encoding endoflagella subunit protein (fla B) from Leptospira interrogans serovar lai].

A pair of oligonucleotide primers were designed by ourselves to amplify the endoflagella gene of L. interrogans serovar lai. A fragment about 840 bp was generated with PCR and inserted into plasmid pUC8 after the fragment and pUC8 were digested respectively with Bam HI and Pst I. A recombinant plasmid (designated as pLF1) was obtained. SDS-PAGE analysis indicated that a 33 kd was expressed in E. coli JM103 harboring pLF1 and the expression level of the protein was 11% of total bacterial soluble proteins. Western blot analysis showed that the protein band could be recognized by the antiserum against the endoflagella (Axiall filament) of Leptospira interrogans serovar lai. Nucleotide seguence data showed an open reading frame encoding 282 aminoacids residues, corresponding to a protein of molecular weight 33.6 kd. The G + C content of endoflagella subunit protein gene was 48 mol%. Therefore, the G + C content of the leptospiral fla B Gene is significantly higher than the reported 39 mol% G + C content of leptospiral genome of L.interrogans serovar lai but similar to the G + C of the Treponema pallidum genome. Comparison of the deduced endoflagellar subunit protein (fla B) amino acid sequence with flagellins from other bacteria revealed a high level of identity with the Treponema pallidum fla B proteins. Immunization/protection experiment was performed on the model of BALB/c mice and showed that the survival rate in the group JM103-pLF1 was higher than that in the group JM103-pUC8, but statistically the difference between them was significant (P < 0.05) and pLF1 did not induce significant levels of agglutinating antibodies against L.interrogans serovar lai.

Amino Acid Sequence↗
PubMed1996

Left ventricular diastolic dysfunction in patients with angina decubitus.

OBJECTIVE: To investigate the relationship between left ventricular diastolic dysfunction and episodes of angina decubitus. METHODS: The study population consisted of three groups, groups I (20 controls) had no cardiovascular diseases. Group II (20 patients) had coronary artery disease (CAD) without angina decubitus. Group III (24 cases with ejection fraction (EF) > 45%) were selected from 26 patients with angina decubitus. RESULTS: Left ventriculography (LVG) showed that left ventricular (LV) first 1/3 filling fraction (1/3FF) was significantly reduced in groups III as compared with groups II and I (P < 0.01). Left ventricular end-diastolic pressure (LVEDP) significantly increased in patients with angina decubitus after LVG as compared with that before LVG (P < 0.01). However, there were no statistically differences in LVEDP, before and after LVG in both groups II and I. CONCLUSIONS: Patients with angina decubitus have abnormalities of LV diastolic filling and decrease in LV compliance.

Adult↗
PubMed1996

Plasma endothelin and atrial natriuretic peptide in normal and hypertensive pregnancy.

OBJECTIVE: To investigate the possible role of endothelin-1 (ET-1) and atrial natriuretic peptide (ANP) in the pathogenesis of pregnancy-induced hypertension (PIH). MATERIAL AND METHODS: A total of 110 normal pregnant women (in three trimesters, labour or postpartum) and 30 patients with PIH were studied by measuring plasma ET-1 and ANP levels by radioimmunoassay; 23 normal non-pregnant women were selected as controls. RESULTS: Compared with normal non-pregnant women, plasma ET-1 levels were significantly decreased in normal pregnant women during all three trimesters. Plasma ET-1 level was significantly increased in the 2nd stage of labour, compared with that in the 3rd trimester. There were significant positive correlation between plasma ET-1 level and mean arterial pressure in normal non-pregnant women and normal pregnant women in all three trimesters. Compared with matched normal pregnant women, plasma ET-1 and ANP levels were significantly increased, while plasma ANP/ET-1 ratio was significantly decreased in PIH patients. Significant positive correlations existed between plasma ET-1 level and mean arterial pressure or the score index of the severity of PIH. After the treatment with magnesium sulfate infusion, plasma ET-1 and ANP levels were significantly decreased, but plasma ANP/ET-1 ratio was significantly increased in PIH patients. CONCLUSIONS: Augmentation of ET-1 secretion and attenuation of ANP function may be responsible for the development of PIH. ET-1 secretion may be indirectly influenced by magnesium in PIH.

Adult↗
PubMed1996

[The changes of plasma nitric oxide in patients with pregnancy induced hypertension].

OBJECTIVE: To determine whether the antepartum and postpartum plasma nitric oxide (NO) levels were changed in pregnancy induced hypertension (PIH). METHODS: 30 patients with PIH and 30 healthy women in their late pregnancy were studied. The antepartum and postpartum plasma NO2-/NO2- levels, the stable metabolic end products of NO, and cyclic guanosine monophosphate (cGMP) were measured with greiss reagent. RESULTS: (1) The plasma concentration of NO2-/NO2- and cGMP in patients with PIH decreased significantly when compared with that of healthy pregnant women (P < 0.01). (2) The concentration of antepartum plasma NO2-/NO2- was markedly lower than that of postpartum one in PIH patients (P < 0.01). (3) There was a negative correlation between the plasma NO2-/NO3- level and systolic blood pressure in PIH (P < 0.01). (4) A positive correlation was seen between plasma NO2-/NO3- levels and cGMP levels in PIH patients (P < 0.01). CONCLUSION: The decrease of NO synthesis may be one of the important factors responsible for PIH.

Adult↗
PubMed1996

[The relationship between onset of labour and concentration of hyaluronic acid and estradiol to progesterone ratio].

OBJECTIVE: To study the changes of serum hyaluronic acid (HA) level and estradiol (E) to progesterone (P) ratio during pregnancy and their relationship with onset of labour. METHODS: 116 normal pregnant women with different gestation age and different phases in labour and 20 postpartum women were studied with 30 cases of nonpregnant women as control. Concentration of HA, E2 and P were determined by radioimmunoassay. RESULTS: Serum concentration of E2, P and their ratio increased gradually during pregnancy and reached their peaks at the onset of labour. HA concentration was similar to nonpregnant women during first and second trimester, however, significantly increased during labour, and then decreased rapidly to nonpregnant level at 2-3 days postpartum; concentration of HA, E2, P and E2/P increased significantly during labour but unrelated to the gestational age when labour began; serum concentration of HA was negatively correlated with the latent phase (r = -0.344, P < 0.05) but not with the active phase. CONCLUSION: HA, E2, P and E2/P may play an important role in the initiation of labour and may be of value in evaluating cervical ripening and facilitating labour management.

Adult↗
PubMed1996

[The internalization of immunotargeting drugs for hepatocellar carcinoma and its significance].

OBJECTIVE: To study the internalization law of immunotargeting drug for hepatocellular carcinoma and its significance. METHODS: Colloidal gold technique and the process of internalization of the immunotargeting drugs, Hab18-ADM and Hab25-ADM, against hepatoma in the targeting cells of human hepatoma cell line SMMC-7721 was used under an electron microscope. RESULTS: 80% of the target cells with gold-labeled particles on the cellular surfaces. The main way of internalization was invariably through a non-coated microinvagination. 18 hours after the intercellular internalization of immunotargeting drugs, the cytoplasmic vacuolization could be visible, even cellular necrosis. The control cells grew well. The above results indicate that after entering into the targeting cells the immunotargeting drugs degrade within the lysosomes, then, ADM arrives at its function site and plays the role of cell toxicity intranuclearly. CONCLUSION: The internalization of Hab 18-ADM and Hab25-ADM is effective, and possesses a good prospect in clinical application.

Antibiotics, Antineoplastic↗