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Biomedical subjects

M Wang

Publications and source records attributed to M Wang.

At least 253 records · Page 14Linked to original sources
PubMed2001

[The relationship between cell proliferation and apoptosis of vestibular epithelium in the developing guinea pig].

OBJECTIVE: The cell proliferation and apoptosis of vestibular epithelium in normal developing guinea pig were observed to elucidate the relationship and effect between proliferation and apoptosis in developing vestibular epithelium. METHODS: Twenty Guinea pigs with different developing ages were used in our studies. Cell proliferation was detected by proliferation cell nuclear antigen (PCNA) immunocytochemistry while apoptosis was detected by TdT-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL) method and transmission electro-microscopy. RESULTS: PCNA staining had been detected in supporting cells but not in hair cells, and the positive cells were gradually decreased with ageing. The differentiated hair cells and supporting cells underwent apoptosis in vestibular sensory epithelium, and TUNEL-positive cells were also markedly decreased with ageing. After birth, TUNEL-positive hair cells were located at the top of ampulla. CONCLUSION: During the development of guinea pig, cell proliferation as well as apoptosis events diminish contemporaneously. The balance between proliferation and apoptosis may regulate the normal number of cells, and is related to guarantee the normal structure and function of inner ear.

Animals↗
PubMed2001

[Surgery of the skull base assisted by sinus endoscope].

OBJECTIVE: To explore the feasibility and clinical value of the endoscopic operations around the skull base. METHODS: A retrospective study was made of 44 cases treated by endoscopic operations. Twenty-five cases underwent intranasal endoscopic operations. RESULTS: Forty of 44 cases were cured by one-stage surgery. One case of cartridge foreign body clamped in clivus was not successfully removed; only window operation and puncture biopsy were done in another case of pituitary adenoma; high cranial pressure has not been completely reduced after operation in the third case with relapsing craniopharyngioma a companied with obstructive hydrocephalus. One case of sphenoidal malignant adenoma involving saddle based and extended laterally was partly resected. Complications were follows: cerebrospinal fluid rhinorrhea in 2 cases, diabetes insipidus in 1 case, all of them were cured by conservative treatment; nasal septum perforation in 1 case, without any treatment. CONCLUSIONS: The endoscopic skull base surgery by intranasal approach is feasibility. Intranasal approach has direct path, slight wound and no wound in face. Combined with operation microscope, sinus endoscope can make up for its limits.

Endoscopy↗
PubMed2001

[Retrospective analysis of supracricoid partial laryngectomy with epiglottis preserved and reconstruction of laryngeal function].

OBJECTIVE: To retrospectively evaluate the curative and functional consequences of supracricoid partial laryngectomy with epiglottis preserved. METHODS: From 1980 to 1996, 78 patients underwent supracricoid partial laryngectomy with the epiglottis preserved. The survival rate and the functional results were analyzed. RESULTS: Overall three-year survival rate was 87.2%(68/78), overall five-year survival rate was 75.6% (59/78), and ten-year survival rate was 21.1% (8/38). All patients resumed normal oral feeding. 97.4% (76/78) achieved tracheal extubation. Respiratory and speaking functions were good. CONCLUSION: Supracricoid partial laryngectomy with epiglottis preserved and reconstruction of laryngeal function not only improved local cancer control, but also preserves laryngeal physiologic function.

Adult↗
PubMed2001

[Studies on original plant of traditional Chinese drug "bai zhi" (radix Angelicae Dahuricae) and its closely related wild plants. I. Morphological and anatomical studies on "bai zhi" and closely related wild plants].

OBJECTIVE: To supplement morphological and anatomical data for confirming the original plant of traditional Chinese drug "Bai Zhi" (Radix Angelicae Dahuricae). METHOD: Morphologocal observation and anatomical study were made on 4 cultivated breeds and closely related wild plants of "Bai Zhi". RESULT: According to morphological and anatomical characteristics discovered in this paper, 7 samples noted above could be divided into 3 groups: 1. 4 breeds ("Chuan Bai Zhi", "Hang Bai Zhi", "Qi Bai Zhi" and "Yu Bai Zhi") and Angelica dahurica var. formosana; 2. A. dahurica; 3. A. porphyrocaulis. CONCLUSION: In the morphological and anatomical point of view, A. dahurica var. formosana is closer to traditional Chinese drug "Bai Zhi" than others.

Angelica↗
PubMed2001

[Studies on original plant of traditional Chinese drug "bai zhi" (radix Angelicae Dahuricae) and its closely related wild plants. II. Karyological and pollen morphological studies on "bai zhi" and closely related wild plants].

OBJECTIVE: To supplement cytobiological and pollen morphological data for confirming the original plant of traditional Chinese drug "Bai Zhi". METHOD: Karyological study and pollen observation were made on "Bai Zhi" and its closely related wild plants. RESULT: Similarities and differences of "Bai Zhi" and its closely related wild plants were found. CONCLUSION: 1. 4 cultivated breeds of "Bai Zhi", Angelica dahurica, A. dahurica var. formosana, A. porphyrocaulis are really closely related plants. 2. A. dahurica var. formosana is closer to traditional Chinese drug "Bai Zhi" than others.

Angelica↗
PubMed2001

[Sequence analysis of the late region of human papillomavirus type 6 genome].

OBJECTIVE: To study variations of genome late region of human papillomavirus type 6 (HPV-6) isolated from Chinese patients with condyloma acuminatum. METHODS: Using overlap PCR design, major capsid protein (L1) and minor capsid protein (L2) genes were separately amplified from clinical samples following HPV type determination, and were further assembled into HPV-6 genome late region sequences after inserting into plasmid and sequencing. RESULTS: Two sequences (GenBank accession number AY015006, AY015008) of HPV-6 late region were assembled, which are 2,869 bp long covering 35% HPV-6 genome and with complete open reading frames (ORFs) for L1 and L2. Compared with prototype sequence, nine point mutations were found, including four missense mutations, three of which were located in L2 ORF. Phylogenetic analysis indicated that the cloned sequences are classified into HPV-6b. CONCLUSIONS: HPV-6 genome late region, especially in L1 ORF, is very conserved (variation rate < 0.28%). The mutation from A to G at position 7081 in HPV-6 genome and from G to A at 7099 may represent region characteristics. This is the first report that describes sequence variations among genome late region of HPV-6 isolated from Chinese patients.

Condylomata Acuminata↗
PubMed2001

[A multicenter study of efficacy and safety of oseltamivir in treatment of naturally acquired influenza].

OBJECTIVE: To evaluate the efficacy and safety of oseltamivir in the treatment of naturally acquired influenza in China. METHODS: A randomized, double-blinded, placebo controlled trial of oseltamivir was conducted in China. Individuals of 18 to 65 years were enrolled presenting within 36 hours of influenzal symptoms and elevated temperature of 37.8 or higher. They should have at least two of the following symptoms: nasal congestion, sore throat, cough, myalgia, fatigue, headache, chill and sweating) during an influenza outbreak in the community. Individuals were randomized either to oseltamivir group (75 mg twice daily for 5 days) or placebo group. RESULTS: A total of 478 individuals were recruited, 16(3.35%) failed to follow up or refused to continue the trial, 3 (0.6%) were excluded immediately before taking medication because they did not meet the entry criteria and 8 (1.7%) individuals were excluded in the blinding review meeting because of protocol violation. Altogether 451 individuals were analyzed for efficacy as intent-to-treat population (ITT) (216 oseltamivir, 235 placebo) and 273 individuals were identified as influenza-infected through laboratory test; they were defined as intent-to-treat infected population (ITTI) (134 oseltamivir, 139 placebo). For safety analysis, 459 individuals were included. In ITTI population, the cumulative alleviation proportion in oseltamivir group was significantly higher than that of placebo group (P = 0.046 6). The median duration of illness was 91.6 hours [95% confident interval (CI) 80.2 - 101.3 hours] in oseltamivir group and 95.0 hours (95% CI 84.5 - 105.3 hours) in placebo group. The median area under the curve (AUC) of decreased total score was significantly higher in oseltamivir group than in placebo group, being 1 382.9 and 1 236.7 score-hours respectively (P = 0.019 6). The median duration of fever and myalgia were 27.9 and 35.5 hours in oseltamivir group, being significantly shorter than that of 51.5 and 36.0 hours in placebo group (P = 0.000 1 and 0.036 1). The median AUC of decreased score for fever and nasal symptom was 337.9 and 108.5 in oseltamivir group, being significantly higher than that of 311.3 and 43.3 in placebo group (P = 0.011 8 and 0.040 3). The proportion of subjects reporting fever in oseltamivir group were significantly lower than that in placebo group at 36, 60, 72, 96, 120 and 132 hours after the initiation of treatment (P = 0.049, 0.001, 0.001, 0.007, 0.007 and 0.030). The amount of paracetamol taken, incidence of secondary complications and antibiotics usage associated with secondary complications were similar in the two groups (P = 0.085 1, 0.944, 1.000). For ITT population, similar results were seen. Adverse events reported were similar in oseltamivir and placebo group. The main adverse events were gastrointestinal symptoms, headache, vertigo, and rashes. CONCLUSION: Oseltamivir was effective and well tolerated in the treatment of early naturally acquired influenza.

Acetamides↗
PubMed2000

Bile duct ligation promotes covalent drug-protein adduct formation in plasma but not in liver of rats given zomepirac.

Acyl glucuronides are reactive electrophilic metabolites of carboxylate drugs, capable of undergoing hydrolysis, rearrangement and covalent binding reactions with proteins in vivo. Such covalent drug-protein adducts may be prerequisites for certain idiosyncratic immune and toxic responses in susceptible individuals. The present study examined the effect of experimental cholestasis on the extent and pattern of formation of protein adducts in plasma and liver of rats given the non-steroidal antiinflammatory drug (NSAID) zomepirac (ZP). Groups of intact, bile-exteriorized and bile duct-ligated rats given a 50 mg/kg i.v. dose of ZP were studied for 24 hr. In intact rats, only 1.4% of the dose was recovered as the sum of ZP, ZP acyl glucuronide (ZAG) and its rearrangement isomers (iso-ZAG) in urine in 24 hr. In bile-exteriorized animals, 0.5% of the dose was recovered in urine in 24 hr, with 31.6% of the dose being recovered in bile (2.7% as ZP, 20.0% as ZAG and 8.9% as iso-ZAG). In the bile duct-ligated group, recovery of dose in 24 hr urine totalled 17.5% (1.7% as ZP, 6.7% as ZAG and 9.1% as iso-ZAG). ZAG and iso-ZAG were measurable in plasma only in the bile duct-ligated group, and covalent binding of ZP to plasma proteins was much higher (5-6 fold) than in intact or bile-exteriorized rats. Total adduct concentrations in liver were not significantly different among the three groups. Immunoblotting using a polyclonal ZP antiserum confirmed that serum albumin was a major target protein in plasma. The major ZP-modified bands in the livers of intact and bile-exteriorized rats were at about 110, 140 and 200 kDa. However, the bands at 110 and 140 kDa were much lower in the livers of bile duct-ligated rats. The results show that about 30% of ZP doses are normally excreted as ZAG and its isomers in bile, with only minor excretion in urine. Bile duct ligation shunts the glucuronide into blood (and urine), strongly promoting adduct formation with plasma proteins, and alters the pattern but not the total quantity of drug-modified proteins formed in the liver.

Animals↗
PubMed2000

Methane emission from a simulated rice field ecosystem as influenced by hydroquinone and dicyandiamide.

A simple apparatus for collecting methane emission from a simulated rice field ecosystem was formed. With no wheat straw powder amended all treatments with inhibitor(s) had so much lower methane emission during rice growth than the treatment with urea alone (control), which was contrary to methane emission from the cut rice-soil system. Especially for treatments with dicyandiamide (DCD) and with DCD plus hydroquinone (HQ), the total amount of methane emission from the soil system and intact rice-soil system was 68.25-46.64% and 46.89-41.78% of the control, respectively. Hence, DCD, especially in combination with HQ, not only increased methane oxidation in the floodwater-soil interface following application of urea, but also significantly enhanced methane oxidation in rice root rhizosphere, particularly from its tillering to booting stage. Wheat straw powder incorporated into flooded surface layer soil significantly weakened the above-mentioned simulating effects. Regression analysis indicated that methane emission from the rice field ecosystem was related to the turnover of ammonium-N in flooded surface layer soil. Diminishing methane emissions from the rice field ecosystem was significantly beneficial to the growth of rice.

Agriculture↗
PubMed2000

Species specificity of human RPA in simian virus 40 DNA replication lies in T-antigen-dependent RNA primer synthesis.

Replication protein A (RPA) is a three-subunit protein complex with multiple functions in DNA replication. Previous study indicated that human RPA (h-RPA) could not be replaced by Schizosaccharomyces pombe RPA (sp-RPA) in simian virus 40 (SV40) replication, suggesting that h-RPA may have a specific function in SV40 DNA replication. To understand the specificity of h-RPA in replication, we prepared heterologous RPAs containing the mixture of human and S.pombe subunits and compared these preparations for various enzymatic activities. Heterologous RPAs containing two human subunits supported SV40 DNA replication, whereas those containing only one human subunit poorly supported DNA replication, suggesting that RPA complex requires at least two human subunits to support its function in SV40 DNA replication. All heterologous RPAs effectively supported single-stranded (ss)DNA binding activity and an elongation of a primed DNA template catalyzed by DNA polymerase (pol) alpha and delta. A strong correlation between SV40 DNA replication activity and large tumor antigen (T-ag)-dependent RNA primer synthesis by pol alpha-primase complex was observed among the heterologous RPAs. Furthermore, T-ag showed a strong interaction with 70- and 34-kDa subunits from human, but poorly interacted with their S.pombe counterparts, indicating that the specificity of h-RPA is due to its role in RNA primer synthesis. In the SV40 replication reaction, the addition of increasing amounts of sp-RPA in the presence of fixed amount of h-RPA significantly reduced overall DNA synthesis, but increased the size of lagging strand, supporting a specific role for h-RPA in RNA primer synthesis. Together, these results suggest that the specificity of h-RPA in SV40 replication lies in T-ag-dependent RNA primer synthesis.

Antigens, Polyomavirus Transforming↗
PubMed2000

The Caenorhabditis elegans heterochronic gene lin-29 coordinates the vulval-uterine-epidermal connections.

BACKGROUND: The development of a connection between the uterus and the vulva in the nematode Caenorhabditis elegans requires specification of a uterine cell called the utse, and its attachment to the vulva and the epidermal seam cells. The uterine pi cells generate the utse and uv1 cells, which also connect the uterus to the vulva. The uterine anchor cell (AC) induces the vulva through LIN-3/epidermal growth factor (EGF) signaling, and the pi cells through LIN-12/Notch signaling. Here, we report that a gene required for seam cell maturation is also required for specification of the utse and for vulval differentiation, and thus helps to coordinate development of the vulval-uterine-seam cell connection. RESULTS: We cloned the egl-29 gene, which is necessary for induction of uterine pi cells, and found it to be allelic to lin-29, which encodes a zinc finger transcription factor that is necessary for the terminal differentiation of epidermal seam cells. In the uterus, lin-29 functioned upstream of lin-12 in the induction of pi cells and was necessary to maintain expression in the AC of lag-2, which encodes a ligand for LIN-12. CONCLUSIONS: The lin-29 gene controls gene expression in the epidermal seam cells, uterus and vulva, and may help to coordinate the terminal development of these three tissues by regulating the timing of late gene expression during organogenesis.

Amino Acid Sequence↗
PubMed2000

A structure-based approach to a synthetic vaccine for HIV-1.

The generation of neutralizing antibodies by peptide immunization is dependent on achieving conformational compatibility between antibodies and native protein. Consequently, approaches are needed for developing conformational mimics of protein neutralization sites. We replace putative main-chain hydrogen bonds (NH --> O=CRNH) with a hydrazone link (N-N=CH-CH(2)CH(2)) and scan constrained peptides for fit with neutralizing monoclonal antibodies (MAbs). To explore this approach, a V3 MAb 58.2 that potently neutralizes T-cell lab-adapted HIV-1(MN) was used to identify a cyclic peptide, [JHIGPGR(Aib)F(D-Ala)GZ]G-NH(2) (loop 5), that binds with >1000-fold higher affinity than the unconstrained peptide. NMR structural studies suggested that loop 5 stabilized beta-turns at GPGR and R(Aib)F(D-Ala) in aqueous solvent implying considerable conformational mimicry of a Fab 58.2 bound V3 peptide determined by X-ray crystallography [Stanfield, R. L. et al. (1999) Structure 142, 131-142]. Rabbit polyclonal antibodies (PAbs) generated to loop 5 but not to the corresponding uncyclized peptide bound the HIV-1(MN) envelope glycoprotein, gp120. When individual rabbit antisera were scanned with linear and cyclic peptides, further animal-to-animal differences in antibody populations were characterized. Loop 5 PAbs that most closely mimicked MAb 58.2 neutralized HIV-1(MN) with similar potency. These results demonstrate the remarkable effect that conformation can have on peptide affinity and immunogenicity and identify an approach that can be used to achieve these results. The implications for synthetic vaccine and HIV-1 vaccine research are discussed.

AIDS Vaccines↗
PubMed2000

Pyrene nucleotide as a mechanistic probe: evidence for a transient abasic site-like intermediate in the bypass of dipyrimidine photoproducts by T7 DNA polymerase.

We recently proposed a mechanism for why dAMP is primarily inserted opposite both T's of photoproducts of TT sites by T7 DNA polymerase [Smith, C. A., Baeten, J., and Taylor, J.-S. (1998) J. Biol. Chem., 273, 21933-21940] that was based on analysis of a recent crystal structure of a complex of this enzyme with a template, a primer, and a dideoxynucleotide. We proposed that indiscriminate insertion of dAMP opposite the 3'-T of each photoproducts takes place via a transient abasic site-like intermediate, with the photoproduct outside the active site, whereas insertion of dAMP opposite the 5'-T takes place with the photoproduct inside the active site. To obtain further support for this mechanism, we have investigated the selectivity of dNMP and pyrene nucleotide (dPMP) insertion opposite each T of the cis,syn, trans,syn-I, trans,syn-II, (6-4), and Dewar photoproducts of TT and opposite a tetrahydrofuran abasic site analogue by the exonuclease-deficient T7 DNA polymerase, Sequenase Version 2.0. Selectivity was determined by a direct competition assay that makes use of a stacked gel to resolve the various extension products. Pyrene nucleotide was chosen for investigation because it has been previously shown to be selectively inserted opposite abasic sites and was therefore expected to probe whether the photoproducts were inside the active site during a particular insertion step. In accord with the proposed mechanism, dPMP was inserted in preference to dAMP opposite the 3'-T of all the photoproducts with the exception of the trans,syn-I product, whereas dAMP was inserted in preference to dPMP opposite the 5'-T of all the photoproducts. In addition to supporting the proposed mechanism, these results suggest that pyrene nucleotide may be a useful probe for investigating the mechanism of DNA damage bypass by polymerases and for characterizing their active sites.

Bacteriophage T7↗
PubMed2000

Induction of mammary differentiation by mammary-derived growth inhibitor-related gene that interacts with an omega-3 fatty acid on growth inhibition of breast cancer cells.

We previously identified and characterized a novel tumor growth inhibitor and a fatty acid-binding protein in human mammary gland and named it the mammary-derived growth inhibitor-related gene (MRG). Here, the effects of MRG on mammary gland differentiation and its interaction with omega-3 polyunsaturated fatty acids (omega-3 PUFAs) on growth inhibition were investigated. MRG protein expression was associated with human mammary gland differentiation, with the highest expression observed in the differentiated alveolar mammary epithelial cells from the lactating gland. Overexpression of MRG in human breast cancer cells induced differentiation with changes in cellular morphology and a significant increase in the production of lipid droplets. Treatment of mouse mammary gland in organ culture with MRG protein resulted in a differentiated morphology and stimulation of beta-casein expression. Treatment of human breast cancer cells with the omega-3 PUFA docosahexaenoic acid resulted in a differential growth inhibition proportional to their MRG expression. MRG-transfected cells or MRG protein treated cells were much more sensitive to docosahexaenoic acid-induced growth inhibition than MRG-negative or untreated control cells. Our results suggest that MRG is a candidate mediator of the differentiating effect of pregnancy on breast epithelial cells and may play a major role in omega-3 PUFA-mediated tumor suppression.

Breast↗
PubMed2000

The important role of residue F268 in ligand binding by LXRbeta.

Liver X receptors (LXRs) are nuclear receptors that regulate the metabolism of cholesterol and bile acids. Despite information on the specificity of their natural ligands, oxysterols, relatively little is known about the ligand binding site in LXRs. The helix 3 region in the ligand binding domain (LBD) of peroxisome proliferator-activated receptors (PPARs) has been implicated in ligand entry. Sequence alignment of LXRs, farnesoid X receptor (FXR), and PPARs identified the corresponding helix 3 region in the LXRbeta LBD. Residues F268 and T272, which are conserved in all the aligned sequences and only in LXRs and FXR, respectively, were replaced with alanine. The effects of these mutations on ligand binding and receptor activation were examined using an in vitro ligand binding assay and a cell based reporter assay, respectively. The LXRbeta mutant F268A did not bind ligand. In contrast, conversion of T272 to alanine has no effect on ligand binding. By transiently expressing a chimeric receptor containing Escherichia coli tetracycline repressor (TetR) and LXRbeta LBD and a reporter with a TetR binding site, we show that mutant F268A lost the ability to activate transcription of the reporter, whereas mutant T272A still has an activity similar to that of the wild-type LXRbeta. These data, consistent with the findings in the in vitro ligand binding assay and our 3D modeling, are the first study that identifies a residue critical for ligand binding in LXRbeta.

Amino Acid Sequence↗
PubMed2000

Error-free and error-prone lesion bypass by human DNA polymerase kappa in vitro.

Error-free lesion bypass and error-prone lesion bypass are important cellular responses to DNA damage during replication, both of which require a DNA polymerase (Pol). To identify lesion bypass DNA polymerases, we have purified human Polkappa encoded by the DINB1 gene and examined its response to damaged DNA templates. Here, we show that human Polkappa is a novel lesion bypass polymerase in vitro. Purified human Polkappa efficiently bypassed a template 8-oxoguanine, incorporating mainly A and less frequently C opposite the lesion. Human Polkappa most frequently incorporated A opposite a template abasic site. Efficient further extension required T as the next template base, and was mediated mainly by a one-nucleotide deletion mechanism. Human Polkappa was able to bypass an acetylaminofluorene-modified G in DNA, incorporating either C or T, and less efficiently A opposite the lesion. Furthermore, human Polkappa effectively bypassed a template (-)-trans-anti-benzo[a]pyrene-N:(2)-dG lesion in an error-free manner by incorporating a C opposite the bulky adduct. In contrast, human Polkappa was unable to bypass a template TT dimer or a TT (6-4) photoproduct, two of the major UV lesions. These results suggest that Polkappa plays an important role in both error-free and error-prone lesion bypass in humans.

2-Acetylaminofluorene↗
PubMed2000

Inactivation of a MAPK-like protein kinase and activation of a MBP kinase in germinating barley embryos.

We provide evidence for involvement of two different 45 kDa protein kinases in rehydration and germination of barley embryos. In dry embryos, a myelin basic protein (MBP) phosphorylating kinase was detected, which could be immunoprecipitated with an anti-MAPK (mitogen-activated protein kinase) antibody. Rehydration of the embryo induced a decrease in activity of this 45 kDa MAPK-like protein kinase. In addition, activity of a MBP kinase of the same molecular weight was subsequently found to be induced. This second MBP kinase activity could not be immunoprecipitated with the anti-MAPK antibody and was induced only in germinating embryos, not in dormant embryos.

Abscisic Acid↗