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Biomedical subjects

N Wang

Publications and source records attributed to N Wang.

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

[Development of donor cells in chicken-duck chimeric embryos].

Chicken W chromosome-specific DNA fragments were obtained after transformation, extraction, purification and digestion with EcoR I of pUGD1201. The W chromosome-specific DNA probe was a 1.2 kb insert, which was labelled by the random-technique using a Digoxigenin Labeling Kit. Chicken PGCs from a line of White Leghorns were microinjected into Maya duck blastoderms at stage X. The embryos at 6,8,9,12,16,18 days of incubation were used to study the development of chicken PGCs in the chimeric embryos. Used chicken W chromosome-specific DNA probes by in situ hybridization, development of donor cells in chicken-duck chimeric embryos were studied. In 54 chimeric embryos, there were different degrees of chimerism in the organs. The chimeric rate of the livers was the highest, which of the gonads was the lowest. It is demonstrated that somatic and germline chimeras can be yielded successfully by transferring stage X chicken blastodermal cells.

Animals↗
PubMed2001

Distribution of enantiomers of trans-tramadol and trans-O-demethyltramadol in central nervous system of rats.

AIM: To investigate the distribution of the enantiomers of trans-tramadol (trans-T) and its active metabolite, trans-O-demethyltramadol (M1), in the central nervous system (CNS). METHODS: After a single ip dose of trans-T hydrochloride or M1, the rats were killed by decapitation. A high performance capillary electrophoresis (HPCE) method was used to determine the concentrations of enantiomers of trans-T and M1 in the serum and different brain tissues, including cerebrospinal fluid (CF), cerebral cortex (CC), corpus striatum (CS), hypothalamus (HY), cerebellum (CE), and medulla oblongata (MO). RESULTS: After ip trans-T hydrochloride, the concentrations of (+)-trans-T were higher than those of (-)-trans-T in the serum and all tested brain tissues; The concentrations of (+)-M1 were lower than those of (-)-M1 in the all tested brain tissues; The concentrations of the enantiomers of trans-T and M1 were the highest in the CC, the lowest in the CF. After ip M1, the concentrations of (+)-M1 were higher than those of (-)-M1 in the serum and all tested brain tissues; The concentrations of the enantiomers of M1 were the highest in the CC, the lowest in the CF. CONCLUSION: The concentrations of the enantiomers of trans-T and M1 varied in the serum and different brain tissues. The distribution of trans-T and M1 in the CNS of rats was stereoselective. The stereoselectivity in the distribution of M1 after M1 injection was different with that after trans-T injection.

Animals↗
PubMed2001

[The influence factors of SO2 removal in flue gas with a pulsed corona discharge].

The influence of the operation parameters on SO2 removal rate with a pulsed corona discharge was studied in this paper, in order to promote the industrial applications of this technology. The flow rate of the flue gas was 1000-3000 m3/h. The SO2 removal rate reached 80%. The range of SO2 concentration in flue gas was 1000-2000 ml/m3. The flue gas temperature was 60 degrees C-80 degrees C. The molecule ratio of NH3 to SO2 was 2. The energy consumption was 3-5 W.h/Nm3. The wire-plane electrode structure and a positive high voltage pulse power supply were used in the experiment.

Sulfur Dioxide↗
PubMed2001

[Mutation and polymorphism in exon 4 of tuberous sclerosis complex gene].

OBJECTIVE: To study the characteristic of mutation and polymorphism in exon 4 of tuberous sclerosis complex gene(TSC1) in Chinese. METHODS: Twenty-five TSC patients and 23 parents from 21 families were enrolled. The mutation of exon 4 in these subjects was identified by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and further confirmed by direct sequencing. RESULTS: The normal controls had the same SSCP bands. In 25 TSC patients, a sporadic case was found to display variant banding pattern and be heterozygous for 352 insA mutation by sequencing. In 23 parents who were normal on clinical examination, another bandshift was found on a mother who had two affected children, which was confirmed as 347A-->C(Val42Val) single nucleotide polymorphism(SNP) by sequencing. CONCLUSION: The 352 insA mutation is a new causative mutation and the 347A-->C is a rare single nucleotide polymorphism.

Adolescent↗
PubMed2001

Comparison of the effects of two types of intraocular lens.

OBJECTIVE: To evaluate the effectiveness and safety of implantation of flexible open-loop anterior chamber intraocular lens (FOAC-IOLs) and scleral fixated posterior chamber intraocular lens (PC-IOLs). METHODS: Sixty-eight eyes of 68 patients with implanted intraocular lenses in the absence of posterior capsular support were reviewed retrospectively. According to the type of intraocular lens, patients were classified into two groups. In group I (30 eyes), FOAC-IOLs was implanted primarily or secondarily. In group II (38 eyes), scleral fixated PC-IOLs was implanted primarily or secondarily. By gonioscopy and ultrasound biomicroscopy (UBM), accurate positions of IOLs' haptics and the relationship between the haptics and surrounding tissues were observed postoperatively and used to evaluate the influence of the two types of IOLs on ocular anterior segments. Follow-up was 6 to 20 months. RESULTS: Best corrected visual acuity of 20/40 or better was achieved in 27 eyes (90.0%) in group I, and 35 eyes (92.1%) in group II and the difference was not statistically significant (P > 0.05). In group I, 23 eyes (76.7%) had a total of 40 complications, while 13 eyes (34.2%) had 19 complications in group II (P < 0.05). Gonioscopy and ultrasound biomicroscopy showed that in group I, all haptics of IOLs contacted with the iris completely and compressed the iris to different degrees, sometimes causing the anterior chamber angles to widen. Anterior synechia of the iris was caused by the haptics of FOAC-IOLs in 12 eyes. Among the 60 IOLs haptics, 39 foot plates of the haptics were properly fixed at the ciliary band; 21 haptics (12 eyes) penetrated through the iris into the stroma of the ciliary body with accompanying recurrent uveitis. In group II, among the 76 IOLs haptics, 52 were adequately fixed in the ciliary sulcus regions, and 8 (8 eyes) were placed below the iris, causing goniosynechia. This type of angle closure was localized, with an open angle on each side of the haptics. The remaining 16 haptics were fixed onto the ciliary crown. CONCLUSIONS: The current sutured mode of scleral fixated PC-IOLs can not ensure that IOLs haptics are placed in the ciliary sulcus. The haptics of FOAC-IOLs compress the iris and may penetrate through the iris into the stroma of the ciliary body. This can cause peripheral iris anterior synechia and chronic recurrent uveitis. The implantation of scleral fixated PC-IOLs is safer and shows better effects than that of FOAC-IOLs.

Aged↗
PubMed2001

[Glaucoma seton implantation surgery via different pathways for complicated glaucoma].

OBJECTIVE: To evaluate the effectiveness of glaucoma seton implantation surgeries via three different pathways for complicated glaucoma. METHODS: Ninety-nine cases (99 eyes) with complicated glaucoma having undergone glaucoma seton implantation surgeries were divided into three groups. Fifty-eight cases were included (58 eyes) in the group with anterior chamber implantation (AC group), 16 cases (16 eyes) were in the group with posterior chamber implantation (PC group) and 25 cases (25 eyes) were in the group with vitreous cavity implantation (VC group). RESULTS: The follow-up ranged from 6 to 34 months (mean 19.6 months). In the AC group, the postoperative intraocular pressure (IOP) of 40 cases (69.0%) was < 21 mm Hg (1 mm Hg = 0.133 kPa) without using any pressure-lowering agents. The postoperative IOP of 6 cases (10.3%) was < 21 mm Hg with pressure-lowering agents. Patients with IOP controlled < 21 mm Hg were altogether 46 cases (79.3%). The IOP of 11 cases (68.8%) in the PC group was controlled without agents and another 1 case (6.2%) was controlled with medications. Therefore, the total success rate was 75.0% (12 cases). The corresponding rates for the VC group were 10 cases (40.0%), 3 cases (12.0%) and 13 cases (52.0%) respectively. Statistical significant difference (chi 2 = 6.525, P = 0.038) was found in the success rates among these 3 groups. But if we excluded cases with neovascular glaucoma, no statistical difference (chi 2 = 4.231, P = 0.121) was found of the success rates among these 3 groups. CONCLUSION: No influence on surgical effectiveness was found among glaucoma seton implantation surgeries via different pathways for complicated glaucoma.

Adult↗
PubMed2001

[Comparison of nerve fiber layer thickness between optical coherence tomography and histomorphometry in glaucomatous monkey eyes].

OBJECTIVE: To correlate the retinal nerve fiber layer (NFL) thickness measured by optical coherence tomography (OCT) in vivo with histomorphometric measurement. METHODS: Four laser-induced glaucomatous eyes of 4 cynomolgus monkeys were studied by OCT scanning a circular area 2.4 mm in diameter around the optic nerve head. The 4 eyes had early or advanced glaucoma. After final OCT measurement, the monkeys were sacrificed and the eyes enucleated. Routine serial section preparations were made, stained with hematoxylin and eosin, and the NFL thickness of 526 sections measured with the aid of a computerized image analysis system was compared with that at the points coincident with the OCT scanned. RESULTS: The mean OCT and histomorphometric NFL thickness in glaucoma were (72.2 +/- 54.5) microm and (61.1 +/- 44.2) microm, after the correction of dehydration 15% (70.3 +/- 51.1) microm respectively. Student's t-test showed that the difference was insignificant (t = 1.895, P > 0.05). CONCLUSIONS: The NFL thickness measured by OCT in vivo correlates well with that by histomorphometry, and the measurement is accurate.

Animals↗
PubMed2001

[Cloning and characterization of syap1, a down regulated gene in human hepatocellular carcinoma].

Using a different fragment DE6 obtained from DD-PCR as probe, a full-length cDNA has been cloned from human liver cDNA library and named as syap1 (Synapse-associated protein 1) because its deduced amino acid sequence is homologous to SAP47 of D. melanogaster. Northern blot analysis reveals that two transcripts of syap1 mRNA are expressed in cultured human liver L-02 cells. Moreover, the syap1 mRNA was also detected in most of adult human tissues by RT-PCR analysis. Down-regulated expression of syap1 mRNA was confirmed by semi-quantitative RT-PCR assay in 5 of 10 (50%) cases of human hepatocellular carcinoma (HCC).

Adult↗
PubMed2001

[Transportation of the enantiomers of trans tramadol and O-demethyltramadol across blood-brain barrier].

AIM: To investigate the transportation of the enantiomers of trans tramadol (trans T) and its active metabolite, O-demethyltramadol (M1) across blood-brain barrier. METHODS: Rats were sacrificed by femoral artery bleeding 1 h after i.p. administration of trans T hydrochloride, 16.7 mg.kg-1 or 50.0 mg.kg-1. Blood, cerebrospinal fluid and cerebral cortex were taken out. The enantiomers of trans T and M1 were analyzed by high performance capillary electrophoresis (HPCE). RESULTS: Among the three tissues, the concentration of each enantiomer of trans T and M1 was the highest in the cerebral cortex, and the lowest in the cerebrospinal fluid. In the serum, the concentration of (+)-trans T was higher than that of (-)-trans T, and the concentrations of the enantiomers of M1 were similar. In the cerebrospinal fluid and cerebral cortex, the concentration of (+)-trans T was higher than that of (-)-trans T, and the concentrations of (+)-M1 was lower than that of (-)-M1. CONCLUSION: The transportation across blood-brain barrier of the enantiomers of trans T and M1 was stereoselective. In the brain tissues, the concentrations of (+)-trans T and (-)-M1 were higher than those of their enantiomers.

Analgesics, Opioid↗
PubMed2001

[Ultrastructure changes of the olfactory epithelium of the patients suffering from dysosmia caused by the chronic sinusitis].

OBJECTIVE: To observe the ultrastructural changes of olfactory epithelium (OE) in patients suffering from dysosmia caused by chronic sinusitis. METHODS: The specimens of olfactory epithelium were obtained from 35 patients operated for chronic sinusitis accompanied by dysosmia. According to the results of light microscope (LM) examination, the OE was divided into three groups by the types of pathological changes: normal, atrophic and respiratory epithelium metaplasia(REM). Transmission electron microscope was used to observe the ultrastructural changes of each group. RESULTS: Under the LM, the surface ultrastructure of the OE showed some abnormal changes: (1) surface microvillus of the supporting cells disappeared; (2) olfactory vesicle changed their shape due to vacuolization; (3) disappearance of canaliculus structure in the olfactory vesicle; (4) the olfactory cilia changed the shape or reduced; some of the reduced cilia underwent metaplasia. The ultrastructural changes of atrophic OE included: (1) minor and moderate atrophy: the organelles and the membrane-limited electron dense vesicles on the upper section of the supporting cells obviously decreased or disappeared, even underwent vacuolization. The basic cell degenerated; (2) serious atrophy: the turbidity of the cell structure, even double cell structure, the nuclei of the cell aggregated as the plaque and vesiculose change or karyopyknosis. As for the cytoplasm, there were the dilation of the ERs, turgidity of the mitochondrion, the disarrangement, diminution and vacuolization. Fasciculate cilia were distributed separately in the REM group. CONCLUSION: There is a positive relationship between the atrophy degree and the degree of the abnormal ultrastructural changes of the OE. The ultrastructural changes of OE in patients suffering from dysosmia caused by chronic sinusitis may provide reference for assessment of the treatment of dysosmia.

Adult↗
PubMed2001

[Expression and significance of serum soluble tumor necrosis factor receptor-I in patients with head and neck neoplasm].

OBJECTIVE: To investigate the expression and significance of serum soluble tumor necrosis factor receptor-I (sTNFR-I) in patients with head and neck neoplasms. METHOD: The study was undertaken to detect serum sTNFR-I levels in 160 head neck cancer patients (including 12 cases of malignant lymphoma, 62 nasopharyngeal cancer, 56 laryngeal cancer, 22 hypopharyngeal cancer, 3 maxillary cancer and 5 thyrophyma), using Sandwich enzyme-linked immuno-sorbent assay. RESULTS: The sTNFR-I levels were significantly higher in patients with carcinoma than those of healthy controls (P < 0.01). The sTNFR-I levels of malignant lymphoma and nasopharyngeal carcinoma were the highest among patients with head and neck neoplasm. The correlations between the serum sTNFR-I levels and the stages of head and neck neoplasms and other laboratory parameters were also analyzed and discussed. CONCLUSION: The serum sTNFR-I levels may reflect the human immunity function, therefore it can be used as a helpful indicator to evaluate the therapeutic effect and monitor the relapses and metastasis of cancer.

Adolescent↗
PubMed2000

Potential live vaccines for HIV.

Potential live vaccines for HIV were developed using an Lpp-OmpA system to target an HIV antigen, reverse transcriptase, or an immunodominant epitope of this enzyme, to the outer membrane of an attenuated strain of Salmonella SL3261. These live vaccines were administered orally to mice, and fecal IgA and helper T cell responses were measured. Results indicated a fecal IgA response specific to HIV reverse transcriptase, as well as a reverse transcriptase-specific helper T cell response, as measured by proliferation assays. Additionally, tests with the epitope vaccines showed a selective cytotoxic CD8 T cell response. These results suggest that this method of antigen targeting to the outer membrane of attenuated bacterial vectors is very promising not only for HIV vaccine development, but also for antigens from other viral or bacterial pathogens, which could be inserted into the Lpp-OmpA protein construct, to elicit mucosal IgA and T cell responses.

AIDS Vaccines↗
PubMed2000

Emissions of methyl halides and methane from rice paddies.

Methyl halide gases are important sources of atmospheric inorganic halogen compounds, which in turn are central reactants in many stratospheric and tropospheric chemical processes. By observing emissions of methyl chloride, methyl bromide, and methyl iodide from flooded California rice fields, we estimate the impact of rice agriculture on the atmospheric budgets of these gases. Factors influencing methyl halide emissions are stage of rice growth, soil organic content, halide concentrations, and field-water management. Extrapolating our data implies that about 1 percent of atmospheric methyl bromide and 5 percent of methyl iodide arise from rice fields worldwide. Unplanted flooded fields emit as much methyl chloride as planted, flooded rice fields.

Atmosphere↗
PubMed2000

Specific binding of ApoA-I, enhanced cholesterol efflux, and altered plasma membrane morphology in cells expressing ABC1.

Mutations of the ABC1 transporter have been identified as the defect in Tangier disease, characterized by low HDL and cholesterol ester accumulation in macrophages. A full-length mouse ABC1 cDNA was used to investigate the mechanisms of lipid efflux to apoA-I or HDL in transfected 293 cells. ABC1 expression markedly increased cellular cholesterol and phospholipid efflux to apoA-I but had only minor effects on lipid efflux to HDL. The increased lipid efflux appears to involve a direct interaction between apoA-I and ABC1, because ABC1 expression substantially increased apoA-I binding at the cell surface, and chemical cross-linking and immunoprecipitation analysis showed that apoA-I binds directly to ABC1. In contrast to scavenger receptor BI (SR-BI), another cell surface molecule capable of facilitating cholesterol efflux, ABC1 preferentially bound lipid-free apoA-I but not HDL. Immunofluorescence confocal microscopy showed that ABC1 is primarily localized on the cell surface. In the absence of apoA-I, cells overexpressing ABC1 displayed a distinctive morphology, characterized by plasma membrane protrusions and resembling echinocytes that form when there are excess lipids in the outer membrane hemileaflet. The studies provide evidence for a direct interaction between ABC1 and apoA-I, but not HDL, indicating that free apoA-I is the metabolic substrate for ABC1. Plasma membrane ABC1 may act as a phospholipid/cholesterol flippase, providing lipid to bound apoA-I, or to the outer membrane hemileaflet.

ATP Binding Cassette Transporter 1↗
PubMed2000

Pharmacological inhibition of phosphatidylcholine biosynthesis is associated with induction of phosphatidylinositol accumulation and cytolysis of neoplastic cell lines.

De novo production of phosphatidic acid (PA) in tumor cells is required for phospholipid biosynthesis and growth of tumor cells. In addition, PA production by phospholipase D has been cited among the effects of certain oncogenes and growth factors. In this report, it has been demonstrated that enhanced phospholipid metabolism through PA in tumor cells can be exploited pharmacologically for development of anticancer agents, such as CT-2584, a cancer chemotherapeutic drug candidate currently in Phase II clinical trials. By inhibiting CTP:choline-phosphate cytidylyltransferase (CT), CT-2584 caused de novo phospholipid biosynthesis via PA to be shunted away from phosphatidylcholine (PC) and into phosphatidylinositol (PI), the latter of which was doubled in a variety of CT-2584-treated tumor cell lines. In contrast, cytotoxic concentrations of cisplatin did not induce accumulation of PI, indicating that PI elevation by CT-2584 was not a general consequence of chemotherapy-induced cell death. Consistent with this mechanism of action, propranolol, an inhibitor of PA phosphohydrolase and phosphatidylcholine biosynthesis, was also cytotoxic to tumor cell lines, induced PI accumulation, and potentiated the activity of CT-2584 in cytotoxicity assays. As expected from biophysical properties of anionic phospholipids on cellular membranes, CT-2584 cytotoxicity was associated with disruption and swelling of endoplasmic reticulum and mitochondria. We conclude that CT-2584 effects a novel mechanism of cytotoxicity to cancer cells, involving a specific modulation of phospholipid metabolism.

Adrenergic beta-Antagonists↗
PubMed2000

Sterol-dependent transactivation of the ABC1 promoter by the liver X receptor/retinoid X receptor.

Tangier disease, a condition characterized by low levels of high density lipoprotein and cholesterol accumulation in macrophages, is caused by mutations in the ATP-binding cassette transporter ABC1. In cultured macrophages, ABC1 mRNA was induced in an additive fashion by 22(R)-hydroxycholesterol and 9-cis-retinoic acid (9CRA), suggesting induction by nuclear hormone receptors of the liver X receptor (LXR) and retinoid X receptor (RXR) family. We cloned the 5'-end of the human ABC1 transcript from cholesterol-loaded THP1 macrophages. When transfected into RAW macrophages, the upstream promoter was induced 7-fold by 22(R)-hydroxycholesterol, 8-fold by 9CRA, and 37-fold by 9CRA and 22(R)-hydroxycholesterol. Furthermore, promoter activity was increased in a sterol-responsive fashion when cotransfected with LXRalpha/RXR or LXRbeta/RXR. Further experiments identified a direct repeat spaced by four nucleotides (from -70 to -55 base pairs) as a binding site for LXRalpha/RXR or LXRbeta/RXR. Mutations in this element abolished the sterol-mediated activation of the promoter. The results show sterol-dependent transactivation of the ABC1 promoter by LXR/RXR and suggest that small molecule agonists of LXR could be useful drugs to reverse foam cell formation and atherogenesis.

ATP Binding Cassette Transporter 1↗