Biomedical subjects

L Wang

Publications and source records attributed to L Wang.

At least 559 records · Page 31Linked to original sources

PubMed2001

[Chromosomal aberration analyzed by comparative genomic hybridization in nasopharyngeal carcinoma].

OBJECTIVE: To identify genetic alteration in primary sporadic nasopharyngeal carcinoma(NPC) in Hunan. METHODS: Comparative genomic hybridization was applied to investigate the genomic imbalance in a series of 20 cases of primary nasopharyngeal carcinomas. RESULTS: The common chromosomal alterations included gains of chromosomes 1q, 2, 3q, 7q,8q,12 as well as losses of chromosomes 3p, 9p, 11q, 16q. CONCLUSION: There are multiple regions of chromosomes with copy number changes in NPC. The tumor suppressor genes and oncogenes on these regions may be involved in the development and progress of nasopharyngeal carcinoma.

Chromosome Aberrations↗

PubMed2001

[Gene diagnosis of factor VIII gene inversion by LD-PCR for 60 patients with severe hemophilia A].

OBJECTIVE: To identify factor VIII(F VIII) gene inversion among 60 patients with severe hemophilia A (HA) in Tianjin region. METHODS: DNA was extracted from peripheral blood of HA patients; F VIII gene inversion was identified by long distance-polymerase chain reaction(LD-PCR) and 0.6% agarose gel electrophoresis. Those with only 11 kb band were diagnosed as the cases of F VIII gene inversion. Those with only 12 kb band were identified as wild type(non-inversion), and those with both 11 kb and 12 kb bands were recognized as inversion carriers. RESULTS: There were 21 patients with F VIII gene inversion, accounting for 35% of the 60 patients with severe HA. CONCLUSION: LD-PCR can be used to detect the F VIII gene inversion directly; it is an effective method for the gene diagnosis of severe hemophilia A.

Chromosome Inversion↗

PubMed2001

Telomerase activity and homozygous deletions of the p16 gene in liver metastases of colorectal carcinoma.

OBJECTIVE: To study the interaction between telomerase activity and abnormalities of the p16 gene in liver metastases of colorectal carcinoma. METHODS: Telomerase activity was detected by a non-isotopic PCR-based telomeric repeat amplification protocol (TRAP) assay, and homozygous deletions of the p16 gene were detected by a semiquantitative multiplex polymerase chain reaction in tissue samples from 24 liver metastases of colorectal carcinoma and 5 primary colorectal carcinomas. RESULTS: Telomerase activity was observed in 19 (79.2%) of 24 liver metastases of colorectal carcinoma. Telomerase activity was also observed in all 5 primary colorectal carcinomas and in 3 of their liver metastatic samples. The incidence of telomerase activity in liver metastases of colorectal carcinoma was not significantly correlated to tumor diameter, number of tumors, cirrhosis, and HBsAg. Homozygous deletions of the p16 gene were found in 9 of 24 (37.5%) liver metastases of colorectal carcinoma. Homozygous deletions of the p16 gene were observed in 2 of the 5 primary colorectal carcinomas and in 1 of the matching liver metastatic cancers. There was a correlation between telomerase activity and homozygous deletions of the p16 gene. CONCLUSIONS: There is a correlation between telomerase activity and homozygous deletions of the p16 gene in liver metastases of colorectal carcinoma, suggesting its crucial role in liver metastases. However, telomerase activation and homozygous deletions of the p16 gene might not be the initiating event in liver metastases of colorectal carcinoma.

Colorectal Neoplasms↗

PubMed2001

Cr (VI) increases tyrosine phosphorylation through reactive oxygen species-mediated reactions.

While Cr (VI)-containing compounds are well established carcinogens, the mechanisms of their action remain to be investigated. In this study we show that Cr (VI) causes increased tyrosine phosphorylation in human lung epithelial A549 cells in a time-dependent manner. N-acetyl-cysteine (NAC), a general antioxidant, inhibited Cr (VI)-induced tyrosine phosphorylation. Catalase, a scavenger of H2O2, sodium formate and aspirin, scavengers of hydroxyl radical (*OH), also inhibited the increased tyrosine phosphorylation induced by Cr (VI). SOD, an inhibitor of superoxide radical (O2*-), caused less inhibition. ESR study shows that incubation of Cr (VI) with the A549 cells generates *OH radical. The generation of radical was decreased by addition of catalase and sodium formate, while SOD did not have any inhibitory effect. Oxygen consumption measurements show that addition of Cr (VI) to A549 cells resulted in enhanced molecular oxygen consumption. These results indicate that Cr (VI) can induce an increase in tyrosine phosphorylation. H2O2 and *OH radicals generated during the process are responsible for the increased tyrosine phosphorylation induced by Cr (VI).

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2001

On the mechanism of Cr (VI)-induced carcinogenesis: dose dependence of uptake and cellular responses.

Cr (VI) compounds are widely used industrial chemicals and are recognized human carcinogens. The mechanisms of carcinogenesis associated with these compounds remain to be investigated. The present study focused on dose-dependence of Cr (VI)-induced uptake and cellular responses. The results show that Cr (VI) is able to enter the cells (human lung epithelial cell line A549) at low concentration (< 10 microM) and that the Cr (VI) uptake appears to be a combination of saturable transport and passive diffusion. Electron spin resonance (ESR) trapping measurements showed that upon stimulation with Cr (VI), A549 cells were able to generate reactive oxygen species (ROS). The amount of ROS generated depended on the Cr (VI) concentration. ROS generation involved NADPH-dependent flavoenzymes. Cr (VI) affected the following cellular parameters in a dose-dependent manner, (a) activation of nuclear transcription factors NF-kappaB, and p53, (b) DNA damage, (c) induction of cell apoptosis, and (d) inhibition of cell proliferation. The activation of transcription factors was assessed by electrophoretic mobility shift assay and western blot analysis, DNA damage by single cell gel electrophoresis assay, cell apoptosis by DNA fragmentation assay, and cell proliferation by a non-radioactive ELISA kit. At the concentration range used in the present study, no thresholds were found in all of these cell responses to Cr (VI). The results may guide further research to better understand and evaluate the risk of Cr (VI)-induced carcinogenesis at low levels of exposure.

Antioxidants↗

PubMed2001

Arsenic-induced NFkappaB transactivation through Erks- and JNKs-dependent pathways in mouse epidermal JB6 cells.

Tumor promoting effects of arsenic are believed to be associated with its transactivation activity on transcription factors, such as AP-1 and NFkappaB. However, the results from different groups studying the effects of arsenic on NFkappaB activation are contradictory in different cell models. Since arsenic is a strong skin carcinogen, we have investigated the activation of NFkappaB by arsenic in a mouse skin epidermal cell line, JB6 cells. Exposure of cells to arsenite or arsenate led to NFkappaB transactivation in mouse epidermal JB6 NFkappaB-luciferase reporter stable transfectants, C141 NFkappaB mass1. This induction of NFkappaB activity by arsenic was dose- and time-dependent. The transactivation of NFkappaB by arsenic appeared to be through activation of Erks and JNKs pathways because increased NFkappaB activity by arsenic could be dramatically inhibited by either pre-treatment of cells with PD98059 or overexpression of dominant negative JNK1. That Erks activation is required for arsenic-induced NFkappaB transactivation was further supported by the findings that arsenic-induced NFkappaB transactivation was impaired in JB6 30.7b cells, which were deficient in Erks.

Animals↗

PubMed2001

[The factors of improving rice transformation efficiency].

The factors influencing the rice transformation frequency have been investigated by using 8 indica and japonica rice cultivars during the transformation procedures, such as induction of calli, selection, and regeneration. The following is the results: The immature embryos were pretreated in 4 degrees C for 4 or 7 days before inoculation, and the regeneration frequency of calli would be increased. High osmotic treatment may increase the possibility of transformation, especially for calli of 6 months or older. The transformation frequency was improved when selection pressure was removed during differentiation period. The V-type selection may be better than the normal selection. There is a difference of differentiation ability among the calli of three periods and it is found that the calli of two or three months are the best for transformation. Proline and DMSO can decrease browning rate of calli.

Dimethyl Sulfoxide↗

PubMed2001

Smoking and lung cancer risk in American and Japanese men: an international case-control study.

Rates of lung cancer in American men have greatly exceeded those in Japanese men for several decades despite the higher smoking prevalence in Japanese men. It is not known whether the relative risk of lung cancer associated with cigarette smoking is lower in Japanese men than American men and whether these risks vary by the amount and duration of smoking. To estimate smoking-specific relative risks for lung cancer in men, a multicentric case-control study was carried out in New York City, Washington, DC, and Nagoya, Japan from 1992 to 1998. A total of 371 cases and 373 age-matched controls were interviewed in United States hospitals and 410 cases and 252 hospital controls in Japanese hospitals; 411 Japanese age-matched healthy controls were also randomly selected from electoral rolls. The odds ratio (OR) for lung cancer in current United States smokers relative to nonsmokers was 40.4 [95% confidence interval (CI) = 21.8-79.6], which was >10 times higher than the OR of 3.5 for current smokers in Japanese relative to hospital controls (95% CI = 1.6-7.5) and six times higher than in Japanese relative to community controls (OR = 6.3; 95% CI = 3.7-10.9). There were no substantial differences in the mean number of years of smoking or average daily number of cigarettes smoked between United States and Japanese cases or between United States and Japanese controls, but American cases began smoking on average 2.5 years earlier than Japanese cases. The risk of lung cancer associated with cigarette smoking was substantially higher in United States than in Japanese males, consistent with population-based statistics on smoking prevalence and lung cancer incidence. Possible explanations for this difference in risk include a more toxic cigarette formulation of American manufactured cigarettes as evidenced by higher concentrations of tobacco-specific nitrosamines in both tobacco and mainstream smoke, the much wider use of activated charcoal in the filters of Japanese than in American cigarettes, as well as documented differences in genetic susceptibility and lifestyle factors other than smoking.

Adult↗

PubMed2001

Inhibition of nicardipine on amygdala kindling in rats.

AIM: To investigate the effects and mechanism of nicardipine, a calcium channel blocker, on amygdala kindling in rats. METHODS: Constant current stimulations were delivered to the right amygdala of the rats once a day. The effects of nicardipine on the development and seizure of amygdala kindling were observed and the content of amino acid neurotransmitters in the brain of kindled rats was determined. RESULTS: Nicardipine (2 mg . kg-1, ip) significantly retarded the development of amygdala kindling (P < 0.01); 2 - 20 mg . kg-1 of nicardipine inhibited amygdala kindled seizure dose-dependently, elevated the afterdischarge threshold, and reduced the Racine's stage; 20 mg . kg-1 of nicardipine significantly increased the content of GABA, a kind of inhibitory amino acid neurotransmitter, in the brain of amygdala kindled rats (P < 0.05). CONCLUSION: Nicardipine inhibits amygdala kindling in rats, and the inhibition mechanism may be related to the blockage of the voltage-operated calcium channels and the enhancement of GABAergic system action in the brain.

Amygdala↗

PubMed2001

Effects of matrine, artemisinin, tetrandrine on cytosolic [Ca2+]i in guinea pig ventricular myocytes.

AIM: To compare the effects of matrine, artemisinin, and tetrandrine on intracellular Ca2+ concentration ([Ca2+]i) in guinea pig ventricular myocytes. METHODS: A single ventricular myocyte was loaded with Fluo 3-acetoxymethyl (Fluo 3-AM). [Ca2+]i was recorded by laser scanning confocal microscope and represented by fluorescence intensity (FI). RESULTS: 1) KCl 60 mmol . L-1 elevated the FI from 299 +/ -19 to 1389 +/- 325 (P < 0.01) in the presence of extracellular Ca2+ 1.8 mmol . L-1. 2) Both matrine and artemisinin at the concentration of 100 micromol . L-1 could enhance the increase of FI by KCl 60 mmol . L-1. The FI values reached 1495 +/- 320 and 1646 +/- 308 from 301 +/- 14 and 299 +/- 16 (P < 0.01), respectively. 3) Both tetrandrine 1, 10, and 100 micromol . L-1 and verapamil 10 micromol . L-1 inhibited the influx of extracellular Ca2+ induced by KCl 60 mmol . L-1. 4) Matrine 1, 10, and 100 micromol . L-1 could elevate the FI in the presence of extracellular Ca2+. The FI values reached 441 +/- 96, 504 +/- 112, and 643 +/- 126 from 303 +/- 27, 300 +/- 32, and 296 +/- 19 (P < 0.05), respectively. 5) Tetrandrine 1 and 10 micromol . L-1 could apparently inhibited Ca2+ release from intracellular calcium stores induced by caffeine 20 mmol . L-1 (P < 0.05). CONCLUSION: Effects of matrine, artemisinin, and tetrandrine on [Ca2+ )]i in ventricular

Alkaloids↗

PubMed2001

[Clinicopathological features of malignant ovarian neoplasms arising from ovarian endometriosis: a report of 26 cases].

OBJECTIVE: To clarify the features of malignant ovarian neoplasms arising from ovarian endometriosis. METHODS: A total of 26 women with malignant ovarian neoplasms arising from ovarian endometriosis were analyzed retrospectively. RESULTS: Dysmenorrhea and pelvic mass were the most common clinical features. Among 18 cases who underwent B-ultrasound or color doppler ultrasound examination, solid foci in the pelvic masses were found in 10 cases. The main histologic types of ovarian malignancy were endometrioid adenocarcinoma and clear cell carcinoma. Microscopically atypical endometriosis with the tumors were found in 15 cases. International Federation of Gynecology and Obstetrics stage: stage I 21(81%) cases, stage II 3(12%) cases, stage III 2 (8%) cases. CONCLUSIONS: Clinical diagnosis of malignant ovarian neoplasms arising from ovarian endometriosis in early stage is difficult, and B-ultrasound examination is more valuable for diagnosis. It is suggested that close serutiny of endometrial hyperplasia, cellular atypia and malignancy in ovarian endometriosis be essential to understand the origin and development of malignant neoplasms arising from ovarian endometriosis.

Adult↗

PubMed2001

[Modulation of multidrug resistance by 1-phenyl-2-palmitoylamino-3-morpholino-1-propanol in SKOV3-adriamycin-resistant cell line].

OBJECTIVE: To study the modulation of mdr1 and P-glycoprotein (P-gp) by 1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (PPMP) in SKOV3-adriamycin-resistant (SKOV3/AdrR) cell line. METHODS: SKOV3/AdrR cells were treated with PPMP, mRNA expression of multidrug resistant (mdr1) gene was analyzed by reverse transcriptase-polymerase chain reaction. Intracellular rhodamine (Rh123) concentration was measured by flow cytometry. RESULTS: PPMP was found to inhibit mdr1 expression of SKOV3/AdrR at the mRNA level. This modulation of gene expression was content dependent and complete inhibition appeared at 25 mumol/L PPMP treatment. PPMP could increase intracellular Rh123 accumulation in SKOV3/AdrR cells. After 15, 25 mumol/L PPMP treatment, Rh123 accumulation in SKOV3/AdrR was markedly enhanced Rh123 fluorescence intensity were 389.98, 426.08 respectively (P < 0.05). CONCLUSIONS: PPMP could modulate mdr1 expression at the mRNA level in a content dependent manner. P-gp mediated outward efflux of cytotoxic agents can be blocked by PPMP in SKOV3/AdrR cell. PPMP possesses multi-drug resistance activity in ovarian cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

[Analysis on landscape ecology literatures in China during recent ten years].

Landscape ecology has achieved great progress since its introduction to China in early 1980s. Based on 619 collections of literatures and 14 collections of books, this paper has all the literatures and books classified, arranged in order and counted on different special subject. According to the results of classified statistics, the authors discuss and analyze how landscape ecology research was going in China during 1990s. Moreover, this paper can also provide scientific basis for those who want to grasp and keep abreast of current focus and trend of landscape ecology in China.

China↗

PubMed2001

[A study on the treatment of secondary glaucoma due to intumescent senile cataract].

OBJECTIVE: To discuss surgical methods of treating secondary glaucoma due to intumescent senile cataract. METHODS: Of 47 inpatient cases (49 eyes) who suffered from secondary glaucoma due to intumescent senile cataract, 28 cases (30 eyes) had been performed the following four different types of operation; (1) extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (PC-IOL) implantation with peripheral iridectomy, (2) ECCE and PC-IOL implantation with segmental iridectomy, (3) ECCE and PC-IOL implantation with trabeculectomy, and (4) five-combined-operation including scleral trephination, cyclodialysis, vitreous paracentesis, ECCE and PC-IOL implantation. RESULTS: The corrected visual acuities in 28 eyes had improved, whereas that in 2 eyes did not improve because of optic nerve atrophy. All the intraocular pressure in 30 eyes was within normal limit, including 12 eyes topically using antiglaucoma drugs. CONCLUSION: Most of patients with secondary glaucoma due to intumescent senile cataract can be cured surgically by iridectomy or trabeculectomy combined with ECCE and PC-IOL implantation. The five-combined-operation is an effective way to treat difficult cases such as long-term disease course, result with antiglaucoma drugs not satisfactory and swelling lens with flat anterior chamber.

Age Factors↗

PubMed2001

[Relationship between placenta growth factor and the pathogenesis of pregnancy induced hypertension syndrome].

OBJECTIVE: To determine whether pregnancy induced hypertension syndrome (PIHs) is associated with placenta growth factor (PLGF). METHODS: PLGF level in the maternal and umbilical venous serum collected from 23 PIHs patients and 20 normotensive controls was measured by enzyme linked immunoassay (ELISA), and expression of PLGF and its mRNA in the placenta and decidua from them was assessed by the immuno-histochemistry and reverse transcriptional-polymerase chain reaction (RT-PCR). RESULTS: (1) PLGF levels in the maternal serum from PIHs [(112.7 +/- 63.8) micrograms/L] were significantly lower than those from normal pregnancies [(200.3 +/- 140.9) micrograms/L], (P < 0.05), and they were correlated with infant birth weight and placental mass (r = 0.4, r = 0.6). (2) Expression of PLGF in sycytiotrophoblast and villous mesenchyme and decidua from PIHs significantly decreased respectively (P < 0.01, P < 0.01, P < 0.05), and expression of PLGF in sycytiotrophoblast was associated with the severity of PIHs (P < 0.05). (3) The transcription of total PLGF mRNA in the placenta and decidua from PIHs decreased significantly (P < 0.05 and P < 0.05 respectively). Particularly, the transcription of PLGF-2 mRNA decreased significantly in the placenta from PIHs. CONCLUSION: The abnormal expression of PLGF may play an important role in the pathogenesis of placental ischaemia hypoxia in PIHs.

Adult↗

PubMed2001

Arsenic trioxide induces multiple myeloma cell apoptosis via disruption of mitochondrial transmembrane potentials and activation of caspase-3.

OBJECTIVE: To investigate the response of multiple myeloma (MM) cells to arsenic trioxide (As2O3) and their possible mechanisms. METHODS: Two MM-derived cell lines RPMI8226 and U266 cells were used as in vitro models. Cell apoptosis was assessed by morphology, flow cytometry, and DNA gel electrophoresis. Mitochondrial transmembrane potentials (delta psi m) were evaluated by measuring cellular Rhodamine 123 staining intensity. Protein expression was analyzed using Western blot. RESULTS: Zero point one to 0.5 mumol/L As2O3 inhibited cell proliferation and 2.0 mumol/L As2O3 induced cell apoptosis, while 1.0 mumol/L As2O3 inhibited proliferation with a weak degree of apoptosis induction in RPMI8226 and U266 cell lines. As2O3-induced apoptosis was accompanied by mitochondrial transmembrane potentials (delta psi m) collapse and caspase-3 activation in the presence of intact membrane. Glutathione depleter buthionine sulfoximine enhanced, while disulfide bond-reducing agent dithiothreitol partially antagonized As2O3-induced delta psi m collapse and apoptosis in MM cells. All-trans retinoic acid (ATRA) could also induce apoptosis in RPMI8226 cells, but it did not show any cooperative effects with As2O3. CONCLUSION: As2O3 exerts apoptosis-inducing and growth-inhibiting effects on MM cells, and mitochondrium is a pivotal and common target of As2O3 for apoptosis induction.

Antineoplastic Agents↗

PubMed2001

Autologous peripheral blood stem cell transplantation in the patients with hematologic malignancies and solid tumors.

OBJECTIVE: To evaluate the long-term therapeutic effects of autologous peripheral blood stem cell transplantation (auto-PBSCT) on the treatment of hematological and solid tumors. METHODS: Fifty-one patients were recruited in this auto-PBSCT study, in which several potentially important parameters were studied including the optimal time for stem cell collection, the dose of stem cell reinfusion, the time of hematopoietic reconstitution, the disease free survival (DFS) and overall survival (OS), complications related to transplantation, and maintenance chemotherapy after auto-PBSCT. RESULTS: After APBSCT, 3-year and 5-year survival rates of NHL were 83.3%; those of AML were 74.7%; those of MM were 37.9% and 19%; those of ALL were 40% and 0% respectively. Hematopoietic reconstitution was greatly promoted by granulocyte colony stimulating factor (G-CSF). The mean time for patients' neutrophil to recover up to > 0.5 x 10(9)/L after APBSCT was 11.14 days in the group of the patients receiving G-CSF in contrast to 17.6 days in the group receiving no G-CSF. The most common complications of transplantation were fever, liver dysfunction and hypokalaemia, which were curable. No death was due to transplantation related complications. CONCLUSION: Comparing with conventional chemotherapy, our study suggests that auto-PBSCT is a very important therapeutic option that can significantly improve the prognosis in the patients with hematological and solid tumors, especially in the patients with AML and NHL.

Adolescent↗

PubMed2001

Effects of free radicals and amyloid beta protein on the currents of expressed rat receptors in Xenopus oocytes.

OBJECTIVE: To investigate the effects of free radicals (FRs) and amyloid beta protein 1-40 (A beta 1-40) on the functions of expressed neurotransmitter receptors (NRs) in Xenopus oocytes. METHODS: Total RNA and messenger RNA (mRNA) was prepared from 3-month-old Wistar rat brain tissues with Promega kits and microinjected into maturated Xenopus oocytes (stages V-VI) with 50 nl (50 ng) for each oocyte. The microinjected oocytes were incubated with modified Bath's solution at 19.0 degrees C +/- 1.0 degree C for receptor expression and their currents were recorded with double electrode voltage clamp technique. Superoxide anion free radicals (SAFRs) were produced via a reaction system (HPX/XO) with hypoxanthine (HPX, 0.05 mol/L) and xanthine oxidase (XO, 0.1 U/L). In order to observe the effects of A beta and SAFRs on the expressed glutamate receptor, HPX/XO and A beta 1-40 were added to incubation solution at 12 h, 24 h and 96 h before recording. RESULTS: The results showed that the oocytes expressed functional NRs originating from rat brain tissues. These NRs included muscarinic acetylcholine (mACh), glutamate (Glu), dopamine (DA), serotonin (5-HT) and gamma-aminobutyric acid (GABA). The current characteristics of expressed receptors were inward currents carried by chloride ion with their equibrilium potentials close to -22 mV. The extent of effect on the current of expressed glutamate receptor from rat brain was different among different A beta concentrations and incubation times. A beta 1-40 at a concentration of 20 nmol/L had little effect on the currents of expressed rat brain glutamate receptors up to 24 h of incubation period; but the currents of glutamate receptor were significantly decreased (25% off, P < 0.01) in the treatment of 60 nmol/L A beta 1-40 over 24 h. Moreover, when 20 nmol/L A beta 1-40 was co-incubated over 12 h with SAFRs produced by the reaction system of HPX/XO, it was found that the currents of expressed rat brain glutamate receptors had been changed markedly. When the oocytes were co-treated with 60 nmol/L A beta 1-40 and SAFRs over a period of 12 h, the currents of glutamate receptor significantly decreased (21% off, P < 0.05), and the decreased percentage reached 52% over 24 h co-treatment with 60 nmol/L A beta 1-40 and SAFRs. In addition, vitamin E had a partial effect against this inhibitory effect. CONCLUSION: The results suggest that A beta has a kind of inhibitory effect upon the current of the glutamate receptor, similar to the effects of free radicals. The effects can be antagonized by vitamin E. These imply that A beta may play a role via inhibiting receptor function in the pathophysiology of Alzheimer's disease.

Amyloid beta-Peptides↗