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Biomedical subjects

D Wang

Publications and source records attributed to D Wang.

At least 523 records · Page 29Linked to original sources
PubMed1999

[Detection of Epstein-Barr viral genome in tumor cells of Warthin's tumor of parotid gland].

OBJECTIVE: To evaluate the relations between Warthin's tumors of salivary gland and Epstein-Barr virus (EBV). METHODS: 75 cases of salivary gland Warthin's tumor and 20 cases of normal salivary gland tissue were examined for to detect EBV genoma by using the polymerase chain reaction (PCR) of DNA, 62 cases of single Warthin's tumor and 13 cases of multiple/bilateral Warthin's tumor's. RESULTS: EBV DNA was detected in 13 cases of single Wathin's tumors, 9 cases of multiple/bilateral Warthin's tumor and 3 cases of normal salivary gland. CONCLUSION: There was a close relationship between EBV and multiple/bilateral Warthin's tumors.

Adenolymphoma↗
PubMed1999

[A gas chromatographic method to decrease the detection limit of trace benzene in CS2 extract].

A method to decrease the detection limit of trace benzene in CS2 extract from coastal water by gas chromatography has been studied. A direct injection port (Shimadzu WBI-17) and a 2 m x 2 mm i.d. column packed with Chromosorb W(AW-DMCS) coated with 10% SE-30 was used. It is simpler and has low detection limit, small sample amount and high repeatability. The experiment showed that the trace water in the organic phase and the too small purge flow of the direct injection port could cause serious tailing of CS2 peak. There was an optimum value of the purge flow (purge flow/total flow = 5%). The minimum detectable limit of benzene was 4 micrograms/L. The repeatability (RSD) was better than 6% and the average recovery was 96.7%.

Benzene↗
PubMed1999

[The influence of pulsed magnetic fields on SOD's activity and MDA value in metabolism of mice].

This experiment aimed to investigate the influence of pulsed extremely-low-frequency-magnetic fields on free radical metabolism of mice. Thirty-two mice were randomly divided into four groups and were exposed to 0 T, 0.25 T, 0.34 T and 0.64 T intensity pulsed magnetic fields of 20 Hz for 40 min. The 0 T exposed group was the control group. The free radical metabolism, SOD's activity and MDA, of mice were measured respectively. The result showed the SOD's activity and MDA of the 0.34 T exposed group were both significantly lower (P < 0.01, P < 0.05) than that of the control group, while the 0.25 T and 0.64 T exposed groups were not significantly different from the control group. This demonstrates that the biological effect of pulsed extremely-low-frequency magnetic fields on free radical metabolism of mice varies and depends on the intensity of the fields. The "window" effect may exist.

Animals↗
PubMed1999

[Ultraviolet blood irradiation therapy for the sudden deafness].

OBJECTIVE: In order to improve curative effect of sudden deafness. METHOD: We adopted ultraviolet blood irradiation (UBI) therapy added conventional pharmacotherapy to treat 70 cases of sudden deafness. RESULT: The general effective rate was 85.6% and there was no complication. In control group we adopted conventional pharmacotherapy only, the general effective rate was 65.7%. There was significant difference between experimental and control groups (P < 0.01). CONCLUSION: The results showed that the UBI is a safety, effective, simple and convenient therapy for the sudden deafness.

Adult↗
PubMed1999

[The submucosal structure of the endolymphatic sac of guinea pigs].

OBJECTIVE: To investigating the submucosal structure of the endolymphatic sac (ES), so as to analyse the role of ES in the function of inner ear. METHOD: The temporal bone of the guinea pigs were cleared in methyl salicylate and inspected under a stereomicroscope. The ultrastructure of endolymphatic sac has been observed by transmission electron microscope. RESULT: The extensive vascular system around the sac and has compact contact with sinus sigmoid. Its submucosal space comprises both arterioles and venules, as well as lymphatic sinus. CONCLUSION: The result suggests that the ES is a very metabolically active structure and has a pressure regulating function. The disturbance of endolymphatic resorptive function seems to result endolymphatic hydrops after the vascular supply poverty of endolymphtic sac. It's may be the causative factor of Meniere's disease.

Animals↗
PubMed1999

[Congenital atresia of the external auditory canal].

OBJECTIVE: To investigate the clinical characters and treatments of congenital aural atresia. METHODS: From 1986 to 1996, 44 patients (50 ears) with congenital aural atresias were operated in the ENT Department of the PLA General Hospital. Postoperative audiological follow-up ranged from 6 months to 9 years. RESULTS: Ossicular chain anomalies were presented in all cases. This consisted most frequently of fusion (54%) or deficiency (36%) of the malleus and the incus with or without fusion to the tympanic wall. Facial nerve abnormalities were seen in 16 ears (32%). After the operation, hearing improvement was found in 33 ears (66%), in which 13 ears (26%) had hearing improvement (pure tone threshold) up to 40 dB. The postoperative complications were external auditory canal stenosis, lateralization of the tympanic membrane and recurrent infections of the cavity and canal skin, with incidences of 34%, 18% and 14%, respectively. CONCLUSION: Maintenance of width of the aural canal and prevention of lateral healing of the transplantated tympanic membrane were crucial in the treatment of congenital aural atresia.

Adolescent↗
PubMed1999

The relationship between expressions of N-myc and c-myc oncogenes in neuroblastoma: an in situ hybridization and immunocytochemical study.

N-myc gene amplification is the most characteristic feature of neuroblastoma. c-myc oncogene, another member of myc gene family, plays an important role in cell proliferation and differentiation. Both of them may contribute to tumorigenesis of neuroblastoma. In this study we use the in situ hybridization and immunocytochemical methods to test the frequencies of N-myc and c-myc expressions in 20 cases of human neuroblastoma at mRNA and protein levels. The positive rates of the expression of N-myc are 90% and 100% detected by in situ hybridization and immunocytochemical methods respectively. The positive rates of c-myc are 80% and 85% respectively. Sixty percent of the 20 specimens tested by in situ hybridization and 55% by immunocytochemistry show an inverse relationship between the expressions of these two oncogenes and this may indicate that there are different gene expression controlling mechanisms in different cases.

Adrenal Gland Neoplasms↗
PubMed1999

Study of loss of heterozygosity at DCC and APC/MCC genetic loci of gastric cancer.

In order to assess the role of the changes of DCC and APC/MCC genes in the development and progression of gastric cancer, the loss of heterozygosity (LOH) of these genetic loci was investigated in 45 surgical specimens of gastric cancer with PCR-RFLP. The rate of LOH was 30.0% (9/30) at APC/MCC gene and 33.3% (15/45) at DCC gene. LOH was found in both intestinal and gastric types of gastric cancer and the rate of LOH of DCC gene was significantly higher in stages III to approximately IV gastric cancer (48.0%) than in stages I to approximately II (15.0%) (P<0.05). LOH of APC/MCC gene could be found in both early and advanced stages of gastric cancer. These findings suggest that changes of DCC and APC/MCC genes are involved in the development and progression of the intestinal and gastric types of gastric cancer.

Adenocarcinoma↗
PubMed1999

Apoptosis of hemopoietic cells in irradiated mouse bone marrow.

Apoptosis of hemopoietic cells in bone marrow following radiation has been rarely reported, let alone studied quantitatively and pathologically. LACA mice were irradiated with 2.5, 4.0, 5.5, and 7.0 Gy gamma-rays, and the bone marrow was examined at 6 hours, 1 day, and 3 days after radiation. Semi-thin and thin sections were examined by light and electron microscopy. The number and area density of the apoptotic cells were assessed by means of a Cambridge Quantimet 970 Image Analyzer. We found that apoptosis occurred in only a few hemopoietic cells in the control mouse bone marrow, whereas 6 hours after radiation there were many apoptotic hemopoietic cells in each sample of irradiated bone marrow. Compared with controls, both the number and area density of the apoptotic cells markedly increased in the bone marrow of animals in every radiation dose group, and the difference was statistically significant (p < 0.01). Furthermore, the number and area density increased as the radiation dose increased. Our findings suggest that apoptosis is the main mode of radiation-induced hemopoietic cell death.

Animals↗
PubMed1999

Overexpression of c-fos and Rb proteins in radiation-induced skin ulcers.

We established an animal model of radiation-induced skin ulcers in rats irradiated with 35 to 55 Gy y-rays. The pathological changes were observed for 1 year. Immunohistochemical studies were performed on 72 radiation-induced skin ulcer specimens using c-fos and Rb protein polyclonal antibodies. We found that the overexpression rate of c-fos was 45.8% and of Rb was 63.9%. The overexpression of c-fos was mainly seen in the nuclei of activated squamous epithelial cells and in some fibroblasts and endothelial cells of arterioles in the deep part of the skin ulcers. The overexpression of Rb had the same localization. Our results suggest that the changes in c-fos and Rb proteins may be related to the poor healing of radiation-induced skin ulcers.

Animals↗
PubMed1999

Overexpression of c-erbB-2 and EGF-R proteins in radiation-induced skin ulcers.

We established an animal model of radiation-induced skin ulcers in rats irradiated with 35-55Gy gamma-rays. The pathological changes were studied for 1 year. Immunohistochemical studies were performed on 72 radiation-induced skin ulcer specimens using c-erbB-2 and epidermal growth factor receptor (EGF-R) protein antibodies. We found that the overexpression rate of c-erbB2 oncoprotein was 59.7% and of EGF-R was 70.8%. The overexpression of c-erbB-2 was chiefly seen in the activated squamous epithelial cells and in the cytoplasm of fibroblasts, endothelial cells, and leiomyocytes of the arteriolar media in the deep part of the ulcers. The overexpression of EGF-R had the same localizations. It is suggested that the overexpression of c-erbB-2 and EGF-R proteins may be due to the poor healing of the radiation-induced skin ulcers.

Animals↗
PubMed1999

Overexpression of p53 and MDM2 proteins in rat radiation-induced skin ulcers.

We established an animal model of radiation-induced skin ulcer in rats that were locally irradiated with 35 to 55 Gy gamma-rays. The pathological changes were observed for 1 year. Immunohistochemical studies using p53 and MDM2 protein polyclonal antibodies were performed on 72 radiation-induced skin ulcer specimens. The results showed that the overexpression rate of p53 protein was 9.7% and of MDM2 was 19.4%. The overexpression of p53 was chiefly seen in the nuclei of the activated squamous epithelial cells and in the fibroblasts and endothelial cells of arterioles in the deeper part of the skin ulcers. The overexpression of MDM2 had the same localizations. These results suggest that the changes of p53 and MDM2 may be related to the poor healing rate of radiation-induced skin ulcers.

Animals↗
PubMed1999

[Studies on decomposed crop residues by FTIR differential analysis].

The decomposing process of corn leaf residues (CLR) was studied by FTIR differential analysis, and the differential spectra were compared with normal spectra. The result showed that the purification process to remove inorganic matters from decomposed CLR could be omitted when differential analysis is used, and the differential spectra were clear and distinct. As far as the studies of decomposed crop residues, the FTIR differential analysis was a convenient and forthright method.

Spectroscopy, Fourier Transform Infrared↗
PubMed1999

Telomerase activity in radiation-induced chronic human skin ulcers.

An increasing activity of telomerase is considered to be a reliable molecular biological marker for malignancy. There is much research work on telomerase detection in malignant tumors, but no such investigation was carried out in chronic skin ulcers induced by radiation. We investigated the levels of telomerase activity in radiation-induced chronic human skin ulcers and the possible relationship between the enzyme and cancer transformation. We used the nonisotopic telomere repeat amplification protocol (TRAP) in 20 cases of chronic human skin ulcers induced by radiation, 5 cases of normal skin, 2 of burned skin, and 5 of carcinoma. Our results showed that the positive rate for telomerase activity was 30% in chronic radiation skin ulcers, 0% in normal and burned skin, and 100% in carcinoma. The telomerase activity in radiation ulcers was weaker than that detected in carcinoma. We suggest that the telomerase activity assay could be used as a marker for predicting the prognosis and the effect of treatment in chronic human skin ulcers induced by radiation.

Cell Transformation, Neoplastic↗
PubMed1998

Signaling by the cytokine receptor superfamily.

A variety of cytokines that regulate functions of multiple lineages share the utilization of receptors that are structurally and functionally related and are referred to as the cytokine receptor superfamily. These receptors associate with one or more of the four mammalian Janus kinases (Jaks) and ligand-induced receptor aggregation results in their activation. Critical roles for Jak3 and Jak2 are demonstrated by the phenotypes of mice that lack each gene. Among the substrates of the Jaks are one or more of the seven members of the signal transducers and activators of transcription (Stats). Each Stat family member plays a critical role in the biological functions of specific cytokines as demonstrated by the phenotype of mice lacking one or more of these genes.

Animals↗
PubMed1998

Role of the alpha2-integrin in osteoblast-specific gene expression and activation of the Osf2 transcription factor.

Extracellular matrix molecules such as type I collagen are required for the adhesion, migration, proliferation, and differentiation of a number of cell types including osteoblasts. Matrix components often affect cell function by interacting with members of the integrin family of cell surface receptors. Previous work showed that collagen matrix synthesis, induced by addition of ascorbic acid to cells, precedes and is essential for the expression of osteoblast markers and induction of the osteocalcin promoter in murine MC3T3-E1 cells. This later response requires OSE2, the promoter element recognized by Osf2 (also called Cbfa1/AML3/PEBP2alphaA), a recently identified osteoblast-specific transcription factor. Osteoblasts express several integrins including alpha2beta1 which is a major receptor for type I collagen. This paper examines the role of the alpha2-integrin subunit in osteocalcin promoter activation and osteoblast differentiation. Disruption of alpha2-integrin-ECM interactions with a blocking antibody or DGEA peptide containing the cell-binding domain of type I collagen blocked activation of the mouse osteocalcin gene 2 promoter by ascorbic acid as well as induction of endogenous osteocalcin mRNA and mineralization. Furthermore, anti-alpha2-integrin blocking antibody or peptide reduced ascorbic acid-dependent binding of Osf2 to OSE2 without affecting levels of transcription factor mRNA. Time course studies revealed that ascorbic acid-dependent binding of Osf2 to OSE2 preceded increases in osteocalcin and bone sialoprotein expression and this increase in Osf2 binding was not accompanied by comparable changes in levels of transcription factor mRNA or protein. Taken together, these studies demonstrate that an alpha2-integrin-collagen interaction is required for activation of Osf2 and induction of osteoblast-specific gene expression. Furthermore, matrix signals may regulate Osf2 through a post-translational pathway or via an accessory factor.

3T3 Cells↗
PubMed1998

Nitric oxide and N-acetylcysteine inhibit the activation of mitogen-activated protein kinases by angiotensin II in rat cardiac fibroblasts.

Angiotensin II acts on the cardiac fibroblast to produce a mitogenic response. Nitric oxide and N-acetylcysteine have been used to determine if oxidative stress influenced the effects of angiotensin II on the cardiac fibroblast. Angiotensin II activated the mitogen-activated protein kinases designated extracellular signal-regulated kinases within 5 min by interacting with the AT1 receptor. This activation was completely independent of protein kinase C and was inhibited when farnesylation was blocked, implicating Ras involvement. Pretreatment of cardiac fibroblasts with either N-acetylcysteine for 8 h or nitric oxide for 10 min suppressed this activation by angiotensin II in a dose-dependent manner. However, when both agents were added, inhibition was essentially complete. This combined effect of N-acetylcysteine and nitric oxide to block ERKs activation also was found if the activity was stimulated by either another growth factor (platelet-derived growth factor) or by the addition of phorbol ester, suggesting the effect was not limited to the receptor site alone. The results are consistent with the hypothesis that hormonal activation of mitogenic steps such as ERKs is influenced by increased oxidative stress, which is reduced by the combined effects of N-acetylcysteine and nitric oxide.

Acetylcysteine↗