Biomedical subjects

X Meng

Publications and source records attributed to X Meng.

At least 73 records · Page 4Linked to original sources

PubMed2000

Screening of novel epilepsy-related genes and isolation and identification of cDNAs.

Twenty cDNA differential fragments were isolated from the hippocampus of rats in epileptic state using mRNA differential display technique. Four fragments were sequenced and compared with the known sequences in the Genebank, which showed that ERG8, ERG11, ERG12 had no significant identity to any known sequences; ERG14 had 64%-69% identity to microtubulin-associated protein of the rat. Because the differential expression of these genes was caused by epilepsy inducer coriaria lactone (CL) and anti-epilepsy drug MK-801 and ERG8 might be a novel candidate epilepsy gene; ERG11 and ERG12 might be novel candidate anti-epilepsy genes. Since the microtubulin-associated protein is closely associated with the collateral sprouting of mossy fibers in the hippocampus of seizured rat, the high expression of ERG14 in the early stage of epilepsy might predict the growth of axon and formation of synapse.

Animals↗

PubMed2000

Dynamic process of information transmission complexity in human brains.

Based on a complexity analysis of mutual information transmission of EEG developed by us [Xu J, Liu Z, Liu R, Yang Q (1997) Physica D 106: 363-374], dynamic processes of the complexity of mutual information transmission in human brains were studied. To diminish possible problems due to coarse graining preprocessing, some new measures of complexity were used. The results show that, just before and after generalized seizures, the complexities of almost all information transmission between different brain areas drop significantly; there is also a temporary decrease of complexity when subjects shift their attention. The above facts suggest that there is a transient decrease of information transmission complexity when brain state changes occur suddenly. Mental arithmetic tasks activate the left temporal lobe to exchange more information with other brain areas. The results hint that the methods used here might be an approach to observe quick processes in the living brain.

Adult↗

PubMed2000

Weak beam under convergent beam illumination

The weak beam technique is now used widely for the determination of stacking fault energies, in particular for intermetallic alloys, and the accuracy of the approach is critically dependent upon the reliability of the relationship between the image and the actual position of the dissociated dislocations. Examining as a model case a dislocation dissociated into two Shockley partial dislocations in Cu at 100 kV for orientations ranging through the g(3g) weak beam condition, image simulations are used to explore the accuracy to which the true spacing between the partial dislocations can be determined from the spacing measured on the image as a function of the dislocation character, the foil thickness, the dislocation depth in the foil, the diffraction condition and the beam convergence. It appears that for image simulations and for the given conditions a beam convergence of about 5 mrad allows to greatly improve the accuracy, and that beam convergence must be taken into account quantitatively when deducing the true partial dislocation spacing as it is the principal parameter controlling the precision in this type of measurement.

Journal Article↗

PubMed2000

Expression vector with DNA of bovine papilloma virus 1 for keratinocyte gene therapy.

Although there are several methods for introducing the genes to keratinocytes in vivo, expression of transgene does not last long enough for effective keratinocyte gene therapy. In this study, we added bovine papilloma virus 1 (BPV) DNA into expression vectors with the lacZ gene driven by metallothionein and keratin 10 promoters, and we transferred them into keratinocytes in vivo using the naked DNA method, and measured beta-gal activity in keratinocytes. The results showed that beta-galactosidase activity of vectors with the BPV DNA was clearly higher than that without the DNA. Moreover, time-course experiment disclosed that the activity of the BPV vector declined at a lower rate than that of the control vector, suggesting this fragment prolonged transgene expression. These results should prove useful for understanding gene regulation in keratinocytes in vivo and for developing potential expression vectors for keratinocyte gene therapy.

Animals↗

PubMed2000

Structural identification of two metabolites of catechins and their kinetics in human urine and blood after tea ingestion.

Tea is a popular beverage consumed worldwide. The metabolic fate of its major constituents, catechins, however, is not well-known. In this study, two catechin metabolites were detected in the urine and plasma of human volunteers after ingestion of green tea. These metabolites were identified by LC/ESI-MS and NMR as (-)-5-(3',4', 5'-trihydroxyphenyl)-gamma-valerolactone (M4) and (-)-5-(3', 4'-dihydroxyphenyl)-gamma-valerolactone (M6). The renal excretion of M4 and M6 had a 3 h lag time and peaked 7.5-13.5 h after ingestion of a single dose of green tea, while (-)-epigallocatechin (EGC) and (-)-epicatechin peaked at 2 h. M4 and M6 were two major tea metabolites with urinary cumulative excretions as high as 8-25 times the levels of EGC and (-)-epicatechin in some of our subjects, and accounted for 6-39% of the amounts of ingested EGC and (-)-epicatechin. Both the metabolites appeared to be produced by intestinal microorganisms, with EGC and (-)-epicatechin as the precursors of M4 and M6, respectively. Repeated ingestion of green tea produced a slight accumulative effect of the metabolites. They were also detected in the plasma, exhibiting kinetics similar to those of the urinary metabolites, and in the feces. Study on these metabolites may help us further understand the cancer chemopreventive actions and other beneficial effects of tea.

Adult↗

PubMed2000

Chemokines as mediators of diseases related to surgical conditions.

Chemokines are important mediators of inflammation. Animal studies suggest that inhibition of chemokine action results in a decrease in inflammation. Novel anti-inflammatory agents directed against chemokines are now available. Surgeons are uniquely positioned to treat multiple chemokine-mediated diseases. In this article, we review the biology and nomenclature of chemokines as well as their role in neutrophil migration. Further, the potential role of chemokines in various diseases related to surgical conditions, including adult respiratory distress syndrome, atherosclerosis, inflammatory bowel disease, and solid organ rejection, is reviewed. Finally, the idea that chemokines could be targets for novel therapeutic agents is discussed.

Animals↗

PubMed2000

Effects of chloride channel inhibitors on H(2)O(2)-induced renal epithelial cell injury.

Oxidative stress contributes to renal epithelial cell injury in certain settings. Chloride influx has also been proposed as an important component of acute renal epithelial cell injury. The present studies examined the role of Cl(-) in H(2)O(2)-induced injury to LLC-PK(1) renal epithelial cells. Exposure of LLC-PK(1) cells to 1 mM H(2)O(2) resulted in the following: depletion of intracellular ATP content; DNA damage; lipid peroxidation; and a loss of membrane integrity to both small molecules, e.g., trypan blue, and macromolecules, e.g., lactate dehydrogenase (LDH), and cell death. Substitution of Cl(-) by isethionate or the inclusion of certain Cl(-) channel blockers, e.g., diphenylamine-2-carboxylate (DPC), 5-nitro-2-(3-phenylpropylamino). benzoate (NPPB), and niflumic acid, prevented the H(2)O(2)-induced loss of membrane integrity to LDH. In addition, the H(2)O(2)-induced loss of membrane integrity was prevented by raising the osmolality of the extracellular solutions, by depletion of cell ATP, and by inhibitors of volume-sensitive Cl(-) channels. However, these maneuvers did not prevent the H(2)O(2)-induced permeability to small molecules or H(2)O(2)-induced ATP depletion, DNA damage, lipid peroxidation, or cell death. These results support the view that volume-sensitive Cl(-) channels play a role in the progressive loss of cell membrane integrity during injury.

Adenosine Triphosphate↗

PubMed2000

The value of serum GPDA-F for the diagnosis of primary hepatocellular carcinoma.

OBJECTIVE: To investigate the role of glycylproline dipeptidyl aminopeptidase isoenzymes in the diagnosis of primary hepatocellular carcinoma (PHC). METHODS: We developed a stage gradient polyacrylamide gel electrophoresis system to separate serum GPDA isoenzymes. Total GPDA activities, alpha-fetoprotein, the sizes of tumors and alanine aminotransferase (ALT) activities were also measured simultaneously and the correlation between GPDA-F and these indices was analyzed. RESULTS: Serum GPDA was separated into two bands, namely fast band (GPDA-F) and slow band (GPDA-S). GPDA-F was negative in all healthy persons as well as in the patients with benign liver filling defects, while it was positive in 85.3% cases of PHC. Liver cirrhosis, chronic hepatitis, extrahepatic carcinoma and metastatic liver carcinoma had low positive rates. GPDA-F was positively correlated with serum total GPDA activities, but had no correlation with AFP and size of the tumors. There was the correlation between GPDA-F and ALT in benign liver diseases, but no correlation between GPDA-F and ALT in PHC. Serial measurements of serum GPDA-F showed that GPDA-F was persistently positive in PHC but might change into negative in benign liver diseases. Dynamic determination of GPDA-F might be helpful to differentiate true positive of PHC from false positive of benign liver diseases. CONCLUSION: GPDA-F is a new serum marker of PHC. Measurement of serum GPDA-F is of value for the diagnosis of PHC, especially for those at early stage or with negative AFP.

Alanine Transaminase↗

PubMed2000

[Stress-corrosion test of TIG welded CP-Ti].

In this study TIG (Tungsten Inert Gas) welded CP-Ti were subjected to stress-corrosion test under 261 MPa in artificial saliva of 37 degrees C for 3 months. No significant difference was noted on mechanical test (P > 0.05). No color-changed and no micro-crack on the sample's surface yet. These results indicate that TIG welded CP-Ti offers excellent resistance to stress corrosion.

Biocompatible Materials↗

PubMed2000

[hCG-PLZF-RARA transgenic mice develop leukemia resembling human chronic myeloid leukemia].

OBJECTIVE: In order to investigate the leukemogenic potential of PLZF-RARA fusion protein in vivo, hCG-PLZF-RARA transgenic mice were generated, in which PIZF-RARA fusion gene was driven by hCG promoter to express in myeloid cells of mice. METHODS: Molecular cloning technology was used to construct hCG-PLZF-RARA gene. The genotype and phenotype of the hCG-PLZF-RARA transgenic mice were analyzed by PCR, RT-PCR, immunofluorescence, morphology of bone marrow (BM) cells, pathology and retinoic acid differentiation assays. RESULTS: Six hCG-PLZF-RARA transgenic mice developed leukemia resembling human chronic myeloid leukemia. TF(tissue factor) was not expressed in BM cells of normal mice nor in mice without the expressed transgene, but it was expressed in mice expessing the transgene. CONCLUSION: PLZF-RARA fusion protein plays a crucial role in leukemogenesis. TF is up-regulated by PLZF-RARA fusion gene.

Animals↗

PubMed2000

[Effects of alfacalcidol on osteoporosis in ovariectomized rats].

OBJECTIVE: To investigate the effects of alfacalcidol on osteoporosis in rats induced by ovariectomy (OVX). METHODS: Fifty-three virgin female Wistar rats of six months old were divided into 6 groups: (1) rats in baseline group (base) were sacrificed what 6 months before OVX, and those in the other 5 groups were either bilaterally OVX or sham-operated (sham) as follows: (2) Sham; (3) OVX baseline (OVXb); (4) OVX end (OVXe); (5) OVX + 17beta-estradiol 20 microgram/kg.(-1) SC. (O + E); and (6) OVX + alfacalcidol 0.1 microgram/kg.(-1) oral (O + VD). Rats in OVXb group were sacrificed 6 weeks after OVX and the others were sacrificed 14 weeks after surgery. Alfacalcidol (TEVA, Israel) was fed orally at 6 weeks after OVX and lasted for 8 weeks. Urine and serum samples were collected before sacrifice to determine the bone turnover markers. The right tibia was processed undecalcified for histomorphometric analysis, and the right femur was prepared for pQCT scanning and bone biomechanical measurement with indentation test. RESULTS: Treatment of OVX rats with alfacalcidol (O + VD) increased tibial cancellous bone volume in histomorphometric analysis (12.0% +/- 1.1% vs 5.8% +/- 1.3%, P < 0.01). pQCT scanning showed that trabecular BMC and BMD were sharply elevated in O + VD group compared with OVXe group, increased 109.2% and 133.1% respectively (P < 0.01). In consistency with these changes in mechanical competency of cancellous bone in distal femur, maximal load was enhanced in O + VD group compared with OVXe group (21.3% +/- 4.0% N vs 7.9% +/- 1.9% N, P < 0.05). All these changes in O + VD group were similar to those in 17beta-estradiol treatment group (O + E). Serum calcium concentration increased in O + VD group. Histomorphometric and biochemical indices of bone resorption reduced in O + VD group. CONCLUSION: Alfacalcidol effectively prevent bone loss in OVX rats and restore partly the trabecula, with evidenced increasing density, contents as well as maximal loads of cancellous bone, and reduce bone resorption.

Adjuvants, Immunologic↗

PubMed2000

[Detection of remnants after removal of medullary thyroid carcinoma].

OBJECTIVE: To assess whether calcium stimulation test or somatostain-receptor (SS-R) imaging could early detect remnants after removal of medullary thyroid carcinoma (MTC). METHODS: Calcitonin stimulation (calcium element 3 mg/kg weight, i.v. 10 min), carcino-embryonic antigen (CEA), gastrin (GST) and vasoactive intestinal peptide (VIP) were tested in 14 patients with postoperative MTC. SS-R imaging was used to localize the remnants after removal of MTC in patients with elevated calcitonin. RESULTS: Calcitonin stimulation test showed that the peak value of serum calcitonin was elevated in all patients, of whom 7 had the elevated vatue of basic calcitonin and peak calcitonin. In the 7 patients, SS-R imaging showed normal CEA, GST and VIP. CONCLUSIONS: It is necessary for patients after removal of MTC to perform calcitonin stimulation test for detecting remnants early. SS-R imaging may be useful for localizing remnants and metastatic foci. CEA, GST and VIP are not significant in monitoring MTC after operation.

Adult↗

PubMed2000

[Apoptosis of endothelial cells in alteration of microvascular permeability in lung during sepsis].

OBJECTIVE: To investigate the apoptosis of endothelial cells in the alteration of microvascular permeability in lung during sepsis. METHODS: Twenty-four male NIH mice were subjected to cecal ligation and puncture (CLP) or sham operation (SO). The microvascular endothelial cells of the lungs were harvested at 3 hours and 12 hours after operation. The apoptosis of endothelial cells (VIII factor related antigen positive cells) in the lungs was determined by 2-color flow cytometry (FITC-labeled VIII factor related antigen and PI) and Apop Tag) in situ apoptosis detection kit in situ. The apoptosis related gene (bcl-2) was detected by RT-PCR. The microvascular permeability in lung tissue was also examined. RESULTS: The apoptosis of microvascular endothelial cells was increased significantly at 12 hours after CLP (5.03 +/- 0.92 vs. 3.48 +/- 1.21, P < 0.05). The increased apoptosis was paralleled with the decrease in bcl-2 gene expression. The microvascular permeability in lung tissue was slightly increased at 3 hours after CLP, but significantly increased at 12 hours after CLP (0.106 +/- 0.008 vs 0.047 +/- 0.003, P < 0.01). CONCLUSIONS: Apoptosis in microvascular endothelial cells seems to be an important reason for the alteration of microvascular permeability.

Animals↗

PubMed2000

[Surgical repair of postinfarction ventricular septal rupture].

OBJECTIVE: To study the characteristics of occurrence of postinfarction ventricular septal rupture (VSR) and preliminarily evaluate the proper timing of operation and its effect. METHODS: Twenty patients with postinfarction VSR were divided into two groups: surgical repair (14 patients), and conventional treatment (6 patients). Clinical data were analyzed and the 14 patients were followed up for 4 months-14 years. RESULTS: The 6 patients died within 6 hours-7 days. Of the 14 patients treated surgically, however, 4 had their ruptures closed by the technique of plication and the rest by prosthetic patches. Concomitant procedures included resection of postinfarction ventricular aneurysm in all 14 patients and coronary artery grafting bypass in 3. Five patients (35.7%) died during peri-operation, and 14.3% had residual ventricular septal defects. 2 patients died of heart failure 7 and 9 years after the operation respectively, 1 was lost to follow-up, and the rest were in good condition. CONCLUSIONS: The proper timing of operation determined by the cardiac function of patients. It is necessary to improve condition of circulation before operation. The mortality rate of emergency operation is high within 3 days after VSR, and residual VSR tends to develop in a week after the repair. Operation should be performed a week after VSR. The early operative mortality is closely related to preoperative cardiogenic shock and postoperative complications.

Adult↗

PubMed2000

[A study on the expression of p16 protein and bcl-2 protein in cutaneous eyelid tumors].

OBJECTIVE: To investigate the relationship between p16 (tumor suppressor) and bcl-2 (apoptosis inhibitor) gene expression and the incidence and development of eyelid malignant tumors. METHODS: Streptavidin-biotin-peroxidase complex immunohistochemical method was used to study the expression of p16 gene and bcl-2 gene in 96 cases with eyelid malignant tumors. RESULTS: In the 96 cases, including 40 cases of basal cell carcinoma (BCC), 33 squamous and 23 sebaceous carcinomas, their p16 protein positive (nuclear staining) rates were 70.0%, 54.6% and 56.5% respectively. The p16 positive rate was negatively correlated to the degree of tumor histological differentiation, and the rate difference between the high differentiated carcinoma and the low differentiated one was significant (P < 0.05). bcl-2 protein positive expression was detected in the cytoplasm. All of the 40 BCCs were bcl-2 positive and nearly all the tumor cells showed positive cytoplasmic expression, while in the 33 specimens of squamous cell carcinoma, only did one show positive focal reaction and the staining in other 32 cases was relatively faint. None of the 23 sebaceous carcinoma expressed bcl-2. CONCLUSIONS: The expression of p16 protein is related to the occurrence and degree of differentiation of eyelid malignant tumors. The over-expression of bcl-2 protein suggests that suppression of apoptosis might play a role in the tumorigenesis of BCC.

Adult↗

PubMed2000

[Study of accuracy of one-piece casted and laser welded bridges].

OBJECTIVE: To assess whether laser welded bridge be fit for the clinical usage, this study compares the accuracy of laser welded multi-unit bridges with one-piece casted bridges. METHODS: A precise stainless mold which was 20 mm length composed of two abutments (one premolar and one molar) and one pontic (two missed teeth) was made. 5 wax patterns of four-unit FPD frame-works in one-piece casting based on the mold were made. After that, they were invested with inner (Bellavest) and outer investment (phosphate and gypsum). Then they were casted with CW-PA (Ni-Cr-Nb) alloys. The other 5 wax patterns of four-unit FPD frameworks were invested and casted in two halves. Each couple of frameworks were ultra-sonic washed in distilled water and inserted to the standard metal FPD mold accurately. Laser welding machine (DL-2002) was used to weld each couple of frameworks at 305V, 20 ms. Both groups of specimens were tested on their mesiodistal span dimensions and the diameters of alloy crowns. Then they were inserted to their original stainless mold, where the marginal fitness was examined. RESULTS: 1. The one-piece casted fixed multi-unit bridge couldn't be inserted to abutments completely because of distortion, while the laser welded bridge could be inserted to abutments completely. The average marginal opening of laser welded bridges was about 74 microns and conformed to clinical standard of fitness. 2. Mesiodistal dimensions of one-piece casted bridges at the inner, bottom and top margins were 19.5600 +/- 0.3877 mm, 41.2206 +/- 0.4140 mm, 41.0598 +/- 0.3379 mm respectively; while those of laser welded bridges were 20.2950 +/- 0.1191 mm, 41.9625 +/- 0.0788 mm, 42.0584 +/- 0.1089 mm, which were obviously close to metal abutments (P < 0.05). 3. The alloy crowns' diameters of one-piece casted bridges were examined as following, the premolar: phi IJ = 9.8386 +/- 0.0567 mm, phi LK = 9.9596 +/- 0.0548 mm, the molar: phi EF = 11.7948 +/- 0.0252 mm, phi HG = 11.9412 +/- 0.0763 mm; The alloy crowns' diameters of laser bridges were as following, the premolar: phi IJ = 9.7927 +/- 0.0636 mm, phi LK = 9.9438 +/- 0.0726 mm, the molar: phi EF = 11.8287 +/- 0.0863 mm, phi HG = 11.8893 +/- 0.1049 mm. There was no significant difference between the two groups (P < 0.05). CONCLUSION: Laser welding greatly improve the fitness of multi-unit fixed bridges.

Dental Abutments↗

PubMed2000

[The position of submaxillary transcutaneous electrical stimulation for obstructive sleep apnea syndrome].

OBJECTIVE: To investigate the effective position of submaxillary transcutaneous electrical stimulation for obstructive sleep apnea syndrome (OSAS). METHODS: With fixed provocative locus of genioglossus and its controlling nerve, 11 normal healthy men and 9 patients with OSAS during awakening were studied to disclose the effect of submaxillary constant-current stimulation under different stimulative radius or intensity and thickness of submaxillary skin. The effects of electric stimulation in 9 OSAS patients with narrowing of the retrotongue-base-pharynx level were compared with the control during sleep. RESULTS: The submental and internal side of mandibular angle was effective loci for stimulating genioglossus. Stimulative radius and intensity of both loci were not significantly different (P < 0.05) and no influence of the skin thickness was found. During sleep, indices of breath disorder (P < 0.05), oxygen saturation (P < 0.05) and clinical symptoms had significantly improved. CONCLUSION: Submaxillary electrical stimulation with fixed provocative locus is effective for the treatment of OSAS. The mechanism is perhaps stimulation of genioglossus pushes the tongue ahead and opens the pharyngeal cavity.

Adult↗

PubMed2000

[Expression of the gene encoding human leukocyte differentiation antigen 5D4].

OBJECTIVE: To make sure that 5D4 cDNA is a full length cDNA and to prepare antigens to make monoclonal antibodies against different epitopes in 5D4 protein. METHODS: Recombinant expression vectors pGEX-5X-3-5D4 (full length) and pGEX-5X-3-5D4 (5'fragment) were constructed. 5D4 polypeptides were expressed in Escherichia coli DH5 alpha. 5D4 mRNA expression was detected in various tissues and cell lines with Northern blot assay and RT-PCR. RESULTS: Northern blot demonstrated five mRNA transcripts of 1.9, 2.4, 3.9, 4.5, and 10.0 kb in length existing and expressing of various extent in various tissues. The 1.9 kb mRNA transcript was observed only in the spleen and the small intestinal tissues. The expression of 5D4 mRNA was different in various cell lines. 5D4 polypeptides were expressed in Escherichia coli DH5 alpha. CONCLUSION: The 1,846 bp 5D4 cDNA is a full length cDNA. A full length 5D4 protein and a 5D4 polypeptide which is the NH2 side to the transmembrane region fused with GST with a molecular weight of 66,000 and 60,000 expressing in Escherichia coli DH5 alpha.

Antigens, CD↗