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Biomedical subjects

J Zheng

Publications and source records attributed to J Zheng.

At least 91 records · Page 5Linked to original sources
PubMed2001

Differential expression of lactate dehydrogenase isozymes (LDH) in human placenta with high expression of LDH-A(4) isozyme in the endothelial cells of pre-eclampsia villi.

To evaluate the role of LDH isozymes in the human placenta during the third trimester, placentae were obtained from patients with normal pregnancy and pre-eclampsia. LDH-A(4)isozyme was immunolocalized primarily in the fetal endothelial cells while LDH-B(4)isozyme was predominantly present in syncytiotrophoblasts. This distinct cellular expression pattern of LDH isozymes was confirmed in HUVE and JEG cells. In addition to demonstrating the presence of five LDH isozymes in the placenta, zymograms showed that there was predominant activity of LDH-A(4)isozyme in HUVE cells and high activity of LDH-B(4)in JEG cells. Quantitative studies of LDH by agarose gel electrophoresis and Northern analysis in patients concluded that LDH-A(4)isozyme was increased in pre-eclampsia. The LDH-A(4)isozyme activity increased (P< 0.01) approx 1.6-fold in pre-eclampsia but there was no difference in the LDH-B(4)isozyme activity between placentae from normal compared to pre-eclampsia pregnancy. The level of LDH-A mRNA was increased (P< 0.05) approx twofold in pre-eclampsia. We conclude that the LDH-A gene in the endothelial cells of the placenta within the fetal microvasculature is increased in pre-eclampsia, probably as a result of hypoxia. LDH-A(4)isozyme activity and gene expression in placental endothelial cells, therefore, is a marker for the endothelial pathology seen in pre-eclampsia.

Blotting, Northern↗
PubMed2001

A molecular marker that is specific to medicinal rhubarb based on chloroplast trnL/trnF sequences.

"Da-Huang" (Radix et Rhizoma Rhei, medicinal rhubarb), a famous and important Traditional Chinese Medicine, has often been confused with the adulterant species in the same genus, Rheum. Through sequencing the trnL (UAA)/trnF (GAA) regions of chloroplast DNA of thirteen species of Rheum (three medicinal rhubarb species and ten adulterant ones), a molecular marker of the medicinal species was found. A pair of PCR primers based on the sequences, was thus designed, which amplified a highly specific DNA fragment in medicinal rhubarb exclusively, and absent in the adulterants at all under an optimized PCR condition.

Base Sequence↗
PubMed2001

Preparation and some physicochemical properties of cross-linked poloxamer hydrogel spheres.

The principal purpose of this paper is to report the preparation of cross-linked poloxamer hydrogel spheres in an aqueous two-phase system without the use of organic solvent and additional emulsifier and physicochemical properties related to drug release. Poloxamer 188 was modified with methacryloyl chloride to obtain the polymerizable derivative (macromer). The aqueous solution of the macromer was mixed with dextran/magnesium sulfate aqueous solution to form a water-in-water emulsion system. After polymerizing the macromer in the dispersion phase, nonporous particles with a mean diameter of micron level were prepared. Both the mean diameter and swelling ratio of spheres can be tailored by varying the starting composition of the preparations. The drug release experiments indicate that the release of vitamin B12 entrapped in the spheres follows first-order kinetics.

Chemical Phenomena↗
PubMed2001

Hidden Markov model analysis of intermediate gating steps associated with the pore gate of shaker potassium channels.

Cooperativity among the four subunits helps give rise to the remarkable voltage sensitivity of Shaker potassium channels, whose open probability changes tenfold for a 5-mV change in membrane potential. The cooperativity in these channels is thought to arise from a concerted structural transition as the final step in opening the channel. Recordings of single-channel ionic currents from certain other channel types, as well as our previous recordings from T442S mutant Shaker channels, however, display intermediate conductance levels in addition to the fully open and closed states. These sublevels might represent stepwise, rather than concerted, transitions in the final steps of channel activation. Here, we report a similar fine structure in the closing transitions of Shaker channels lacking the mutation. Describing the deactivation time course with hidden Markov models, we find that two subconductance levels are rapidly traversed during most closing transitions of chimeric, high conductance Shaker channels. The lifetimes of these levels are voltage-dependent, with maximal values of 52 and 22 micros at -100 mV, and the voltage dependences of transitions among these states suggest that they arise from equivalent conformational changes occurring in individual subunits. At least one subconductance level is found to be traversed in normal conductance Shaker channels. We speculate that voltage-dependent conformational changes in the subunits give rise to changes in a "pore gate" associated with the selectivity filter region of the channel, producing the subconductance states. As a control for the hidden Markov analysis, we applied the same procedures to recordings of the recovery from N-type inactivation in Shaker channels. These transitions are found to be instantaneous in comparison.

Animals↗
PubMed2001

Anesthetic-like interaction of the sleep-inducing lipid oleamide with voltage-gated sodium channels in mammalian brain.

BACKGROUND: cis-9,10-Octadecenoamide (cOA) accumulates in cerebrospinal fluid during sleep deprivation and induces sleep in animals, but its cellular actions are poorly characterized. In earlier studies, like a variety of anesthetics, cOA modulated gamma-aminobutyric acidA receptors and inhibited transmitter release/burst firing in cultured neurones or synaptoneurosomes. METHODS: Here, radioligand binding ([3H]batrachotoxinin A 20-alpha-benzoate and mouse central nervous system synaptoneurosomes) and voltage clamp (whole cell recording from cultured NIE115 murine neuroblastoma) confirmed an interaction with neuronal voltage-gated sodium channels (VGSC). RESULTS: cOA stereoselectively inhibited specific binding of toxin to VGSC (inhibitor concentration that displaces 50% of specifically bound radioligand, 39.5 microm). cOA increased (4x) the Kd of toxin binding without affecting its binding maximum. Rate of dissociation of radioligand was increased without altering association kinetics, suggesting an allosteric effect (indirect competition at site 2 on VGSC). cOA blocked tetrodotoxin-sensitive sodium currents (maximal effect and affinity were significantly greater at depolarized potentials; P < 0.01). Between 3.2 and 64 microm, the block was concentration-dependent and saturable, but cOA did not alter the V50 for activation curves or the measured reversal potential (P > 0.05). Inactivation curves were significantly shifted in the hyperpolarizing direction by cOA (maximum, -15.4 +/- 0.9 mV at 32 microm). cOA (10 microm) slowed recovery from inactivation, with tau increasing from 3.7 +/- 0.4 ms to 6.4 +/- 0.5 ms (P < 0.001). cOA did not produce frequency-dependent facilitation of block (up to 10 Hz). CONCLUSIONS: These effects (and the capacity of oleamide to modulate gamma-aminobutyric acidA receptors in earlier studies) are strikingly similar to those of a variety of anesthetics. Oleamide may represent an endogenous ligand for depressant drug sites in mammalian brain.

Animals↗
PubMed2001

Regulation of human immunodeficiency virus type 1 infection, beta-chemokine production, and CCR5 expression in CD40L-stimulated macrophages: immune control of viral entry.

Mononuclear phagocytes (MP) and T lymphocytes play a pivotal role in the host immune response to human immunodeficiency virus type 1 (HIV-1) infection. Regulation of such immune responses can be mediated, in part, through the interaction of the T-lymphocyte-expressed molecule CD40 ligand (CD40L) with its receptor on MP, CD40. Upregulation of CD40L on CD4+ peripheral blood mononuclear cells during advanced HIV-1 disease has previously been reported. Based on this observation, we studied the influence of CD40L-CD40 interactions on MP effector function and viral regulation in vitro. We monitored productive viral infection, cytokine and beta-chemokine production, and beta-chemokine receptor expression in monocyte-derived macrophages (MDM) after treatment with soluble CD40L. Beginning 1 day after infection and continuing at 3-day intervals, treatment with CD40L inhibited productive HIV-1 infection in MDM in a dose-dependent manner. A concomitant and marked upregulation of beta-chemokines (macrophage inhibitory proteins 1alpha and 1beta and RANTES [regulated upon activation normal T-cell expressed and secreted]) and the proinflammatory cytokine tumor necrosis factor alpha (TNF-alpha) was observed in HIV-1-infected and CD40L-treated MDM relative to either infected or activated MDM alone. The addition of antibodies to RANTES or TNF-alpha led to a partial reversal of the CD40L-mediated inhibition of HIV-1 infection. Surface expression of CD4 and the beta-chemokine receptor CCR5 was reduced on MDM in response to treatment with CD40L. In addition, treatment of CCR5- and CD4-transfected 293T cells with secretory products from CD40L-stimulated MDM prior to infection with a CCR5-tropic HIV-1 reporter virus led to inhibition of viral entry. In conclusion, we demonstrate that CD40L-mediated inhibition of viral entry coincides with a broad range of MDM immune effector responses and the down-modulation of CCR5 and CD4 expression.

CD40 Ligand↗
PubMed2001

Contrast-enhanced MR imaging of coronary arteries: comparison of intra- and extravascular contrast agents in swine.

PURPOSE: To compare the efficacy of an intravascular contrast agent, gadomer-17, in improving magnetic resonance (MR) imaging of coronary arteries with that of an extravascular agent, gadopentetate dimeglumine, in pigs. MATERIALS AND METHODS: Eight pigs underwent imaging after three injections: 0.20 mmol of gadopentetate dimeglumine per kilogram of body weight and 0.05 and 0.10 mmol/kg gadomer-17. Coronary images were acquired repeatedly after each injection by using an inversion-recovery-prepared segmented three-dimensional sequence with either breath holding (n = 4) or respiratory gating (n = 4). Coronary artery-to-myocardium contrast-to-noise ratios (CNRs) were compared between injections. RESULTS: At breath-hold imaging, substantial CNR improvement over precontrast images was observed in images acquired during the first pass of gadopentetate dimeglumine in coronary arteries and up to 6 and 10 minutes after 0.05 and 0.10 mmol/kg of gadomer-17 injections, respectively. The CNR with 0.10 mmol/kg of gadomer-17 was 20% (P <.05) higher than that with gadopentetate dimeglumine at first-pass imaging. At respiratory-gated imaging, significant CNR improvement (P <.05) over precontrast images was observed in images acquired up to 10, 30, and 50 minutes after gadopentetate dimeglumine and both gadomer-17 injections, respectively. The CNR on the first images obtained after 0.10 mmol/kg gadomer-17 injection was 168% (P <.05) higher than that on the images obtained after gadopentetate dimeglumine injection. CONCLUSION: Gadomer-17 provided greater and more persistent CNR improvements than did gadopentetate dimeglumine; further evaluation of its utility for coronary imaging in humans is warranted.

Animals↗
PubMed2001

Coronary arteries: magnetization-prepared contrast-enhanced three-dimensional volume-targeted breath-hold MR angiography.

A volume-targeted contrast agent-enhanced breath-hold coronary magnetic resonance angiographic technique was optimized and evaluated in 16 volunteers. Substantial increases in coronary signal-to-noise ratio, contrast-to-noise ratio, lengths of depiction, and vessel sharpness were observed on enhanced images. The imaging approach with two 20-mL injections of contrast agent covers the left and right coronary arteries in two breath holds and is a promising method for coronary imaging.

Adult↗
PubMed2001

Leukotoxin-diol: a putative toxic mediator involved in acute respiratory distress syndrome.

Leukotoxin is clinically associated with acute respiratory distress syndrome (ARDS). Recently, we found that leukotoxin-diol, the hydrated product of leukotoxin, is more toxic than the parent leukotoxin in vitro (Moghaddam and colleagues, Nature Med. 1997;3:562-566). To test if this difference in the toxicity of leukotoxin and leukotoxin-diol exists in vivo, Swiss Webster mice were administered leukotoxin or leukotoxin-diol. All mice treated with leukotoxin-diol died of ARDS-like respiratory distress, whereas the animals exposed to leukotoxin at the same dose survived. Histopathologic evaluation of the lungs revealed massive alveolar edema and hemorrhage with interstitial edema around blood vessels in the lungs of mice treated with leukotoxin-diol, whereas the lungs of mice treated with identical doses of leukotoxin had perivascular edema only and little change in alveolar spaces. Immunohistochemistry showed that the soluble epoxide hydrolase responsible for the hydrolysis of leukotoxin to its diol is concentrated in the vascular smooth muscle of small and medium-sized pulmonary vessels. In addition, 4-phenylchalcone oxide, an inhibitor of soluble epoxide hydrolase, was found to decrease the mortality induced by leukotoxin but had no effect on mortality induced by leukotoxin-diol. These studies provide strong in vivo evidence that leukotoxin may act as a protoxicant and that the corresponding diol is a putative toxic mediator involved in the development of ARDS.

Animals↗
PubMed2001

Current progress in the development and use of artemether for chemoprophylaxis of major human schistosome parasites.

Human schistosomiasis, a chronic and debilitating parasitic disease of the tropics, is ranked second after malaria in terms of public health importance. At present, there is no vaccine available, and chemotherapy is the cornerstone of schistosomiasis control. Praziquantel is the drug of choice. Oxamniquine has become difficult to obtain and metrifonate has recently been withdrawn from the market. Rapid re-infection following treatment and concern about praziquantel resistance called for the search of novel drugs for prevention and cure of schistosomiasis. Significant progress has been made with artemether, the methyl ether of dihydroartemisinin, already widely used for the treatment of malaria. The present article reviews the literature that led to the development of artemether for chemoprophylaxis in schistosomiasis, and it summarises the experiences so far obtained with its use to control schistosomiasis in different endemic settings. Topics covered include an overview of the global burden of schistosomiasis and approaches for its control; the nature and features of artemisinin and related derivatives, initially discovered as antimalarials, other bioactivities, and their recent discovery of antischistosomal properties; a historic account disclosing the antischistosomal activity of artemether; in vivo assessment of drug susceptibility of different developmental stages of schistosome parasites; artemether-induced pathology evidenced by scanning and transmission electron microscopy; the possible mechanism of action; in vivo studies with combination therapy of artemether and praziquantel; results of randomised controlled clinical trials of oral artemether for the prevention of patent infection and morbidity; and, ultimately the translation of this knowledge into public health action in different endemic settings towards a more integrated approach of schistosomiasis control.

Animals↗
PubMed2001

[Cardiac arrhythmias in pilots under positive (+Gz) acceleration].

OBJECTIVE: To study the relationship between cardiac arrhythmias and autonomic nervous regulation in pilots under +Gz acceleration. METHOD: Dynamic ECG during +Gz exposures in 36 orthostatic intolerance pilots and 62 healthy pilots were analysed and compared. RESULT: The orthostatic intolerance pilots had obviously lower +Gz tolerance and more cardiac arrhythmias. The cardiac arrhythmias could affect +Gz tolerance. CONCLUSION: The cardiac arrhythmias under +Gz acceleration could be taken as an index of evaluating cardiovascular compensatory function and warning against acceleration (+Gz) induced loss of consciousness (G-LOC).

Acceleration↗
PubMed2001

Aortic root replacement.

OBJECTIVE: To report our operative experience with aortic root replacement in 231 patients with aortic root aneurysm and discuss the current indications, methods, and surgical techniques. METHODS: Between January 1994 and August 1999, a group of 231 consecutive patients underwent aortic root replacement at our hospital, with 13 being treated on an emergency basis. There were 189 men and 42 women, ranging in age from 14 to 69 years. The diameter of the aneurysm varied from 4.5 to 11 cm. Among this group, 145 had isolated aortic root aneurysms, 65 suffered from DeBakey type I aortic dissection, and the remaining 21 were diagnosed as having DeBakey type II aortic dissection. Aortic valve regurgitation occurred in all cases. Aortic root replacement was performed with composite valved graft in 229 patients, and in 2 patients the aortic valve was preserved. RESULTS: The hospital mortality rate was 3.03% (7 patients). Early complications included re-exploration for bleeding in 6 patients, pericardial effusion in 9, as well as cerebral infarction, pleural effusion, and pneumothorax in 2 patients each. One hundred and seventy-five patients (78.12%) were followed up, with a mean follow-up time of 15.7 +/- 13.1 months (range, 2 weeks to 65 months). One patient died from lower-limb embolism and renal dysfunction 3 months postoperatively. Three patients died from postoperative anticoagulation accidents. The preoperative and postoperative mean left ventricular end-diastolic diameters were significantly different (68.1 +/- 9.4 mm, range 54 to 112 mm; vs 54.8 +/- 8.2 mm, range 38 to 88 mm; P < 0.001). CONCLUSIONS: Once a diagnosis of acute aortic root dissecting aneurysm is made, the patient should undergo surgery as soon as possible if the general conditions permit. Aortic aneurysm without dissection or with chronic dissection should be operated if the diameter of the aneurysm is greater than 5 cm.

Adolescent↗
PubMed2001

Identification of metastasis associated gene G3BP by differential display in human cancer cell sublines with different metastatic potentials G3BP as highly expressed in non-metastatic.

OBJECTIVE: To investigate genes involved in cancer metastasis, mRNA differential display was used to compare the levels of gene expression in two cell sublines derived from human giant cell carcinoma of lung (PG) which had different metastatic potentials. METHODS: Using in vivo tumorigenicity and a spontaneous metastasis assay in nude mice, two sublines (BE1, LH7) from human giant cell carcinoma of lung (PG) with different metastatic potentials were isolated and characterized. mRNA differential display was used to compare the levels of gene expression between them and the obtained results were confirmed by Northern hybridization. RESULTS: One differentially expressed band was nearly identical (99% homology) to Ras-GTPase-Activating protein SH3 domain binding protein (G3BP). G3BP displayed a strong expression in LH7 (non-metastatic in recipient nude mice) and a very weak expression in BE1 (100% metastatic frequency). The same different expression level of G3BP was detected in Northern hybridization with another panel of cell sublines with different metastatic potentials (established in our lab) derived from human prostate carcinoma cell line PC-3M. CONCLUSION: Our results indicate that G3BP was implicated in cancer metastasis because of its differential expressions in the two panels of cell sublines with different metastatic potentials.

Animals↗
PubMed2001

[The prognostic research of expression and relationship between Helicobacter pylori of c-met oncogene correlation with gastric mucosal proliferation].

OBJECTIVE: To determine whether there is a relationship between Helicobacter pylori (Hp) and expression of c-met oncogene and proliferating cell nuclear antigen (PCNA) in gastric mucosal lesions, and prognostic significance of gastric carcinomas(GC). METHODS: Expression of c-met and PCNA were investigated in 145 gastric mucosal lesions by using immunohistochemistry. Hp was examined by Warthin-Starry method. RESULTS: For chronic superficial gastritis (CSG), chronic atrophic gastritis and intestinal metaplasia (CAS + IM), dysplasia(DYS), early GC and advanced GC, the positive rates of c-met and PCNA were higher in IM, DYS and GC than in CSG (P < 0.05). Expressions of c-met and PCNA increased with the increasing proliferation of gastric mucosa, in rank correlation test, they had a close relationship (P < 0.01). Expressions of c-met and PCNA were correlated significantly with histologic type, serosal invasion and lymph node metastasis. In particular, the expression of c-met and PCNA were significantly higher in Borrmann type 4 GC, type 3 GC and type 1, 2 than in early GC(P < 0.05). By rank correlation test, c-met and PCNA have a close relationship (P < 0.001). Expressions of c-met of Hp positive were higher than Hp negative in intestinal GC (P < 0.05). Expressions of c-met were correlated significantly with Hp positive in CAG + IM, DYS and GC. The survival rate of patients with Hp infection was significantly poorer than that of patients with Hp non-infection. CONCLUSIONS: The expression of c-met may be is associated with proliferation and malignant transformation of gastric mucosa. These results suggest that expression of c-met may be a new prognostic factor in gastric carcinoma. Hp infection and expression of c-met may be associated with in proliferation and malignant transformation of gastric mucosa. Hp infection is associated with prognosis of gastric carcinoma.

Cell Proliferation↗
PubMed2001

[Study on the optimal perinatal health care and child health care surveillance systems].

OBJECTIVES: To study the establish an optimal perinatal health care (PHC) surveillance system and an child health care (CHC) surveillance system in China, that can provide better health care services for women and children. METHODS: All women receiving marital check-ups are issued PHC booklets and then their menstrual dates are recorded regularly. If a woman is confirmed to be pregnant, she will receive her first prenatal exam. Subsequent prenatal exams and visits will be followed and recorded accordingly. CHC data will be collected regularly during the provision of routine child health care services. RESULTS: Surveillance systems have been set up in 32 project counties/cities in China, comprising more than 20 million people. The surveillance systems have smoothly been conducted for eight years since 1993. CONCLUSION: The surveillance systems have been proved to be adaptable under China's context. Both PHC and CHC systems seemed to be helpful in improving the health care services as well as the health condition of mothers and children in the areas.

Adult↗
PubMed2001

[Reversed trabeculectomy for treatment of glaucoma].

OBJECTIVE: To reduce the postoperative blocking of the filtration canal in routine trabeculectomy with modification. METHODS: The modification of the procedure of routine trabeculectomy was that one end of the 4.0 mm x 1.5 mm deep layer scleral tissue including part of trabecular meshwork was not cut. Instead, the free end of the strip of deep scleral tissue was vertically rotated and sutured on the deep layer of the scleral bed posterior to it. The projection of the strip was utilized to prevent postoperative blocking of filtration canal. RESULTS: The mean period of postoperative follow-up was 23.5 months (range, 12 -- 36 months). In the treatment group (38 eyes of 33 cases), the intraocular pressure (IOP) was lowered from preoperative (25.41 plus minus 2.41) mm Hg to postoperative (14.74 plus minus 0.90) mm Hg. The IOP was lowered from preoperative (24.96 plus minus 1.35) mm Hg to postoperative (19.40 plus minus 1.43) mm Hg in the control group (40 eyes of 33 cases). The success rates were 94.7% and 77.5% in the treatment and control group respectively. CONCLUSIONS: The modified trabeculectomy is safe, easy to perform, and can effectively relieve the postoperative blocking of the filtration canal, control postoperative IOP and reduce postoperative recurrence.

Adult↗