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Biomedical subjects

M Yang

Publications and source records attributed to M Yang.

At least 289 records · Page 16Linked to original sources
PubMed1998

[The effect of nimodipine on retinal blood flow in pregnancy induced hypertension].

OBJECTIVE: To assess the effects of nimodipine on retinal blood flow in patients with pregnancy induced hypertension (PIH). METHODS: Fourteen patients were studied with color flow Doppler before and after 30 mg nimodipine administered orally, while other fourteen patients received intravenous magnesium sulfate as control group. Central retinal artery flow velocity waveforms were measured and pulse index (PI) were calculated. RESULTS: Nimodipine reduced the central retinal artery PI significantly from 0.92 +/- 0.14 to 0.75 +/- 0.22. It also reduced systolic blood pressure from 20.7 +/- 2.5 kPa to 19.8 +/- 1.5 kPa and diastolic blood pressure from 14.4 +/- 2.3 kPa to 13.6 +/- 1.9 kPa. CONCLUSIONS: Nimodipine may dilate central retinal arteries. Changes in pulsatility index in retinal arteries maybe indicative of similar changes in other cerebral vessels. Nimodipine may be another choice of PIH therapy.

Adult↗
PubMed1998

Long-term efficacy of recombinant interferon alpha 2a in the treatment of chronic hepatitis C: a randomized prospective study comparing two dose schedules in Chinese patients.

OBJECTIVE: To compare the long-term efficacy of a dose of 3 million units (MU) of r-IFN alpha 2a (IFN-alpha 2a) three times a week (t.i.w.) for 6 months with a starting dose 6 MU for 3 months and subsequent reduction to 3 MU t.i.w for further 3 months. METHODS: Sixty-eight serological and histological chronic hepatitis C patients with elevated serum alanine aminotransferase (ALT) were enrolled and randomized into two groups. Sixty-three patients were completed with full course of treatment. Five patients were withdrawn from trial (2 due to personal reasons and 3 due to adverse drug reactions during treatment). Thirty patients received 6 MU IFN-alpha 2a t.i.w., 3 months followed by 3 MU t.i.w. for another 3 months (Group A). Thirty-three patients received 3 MU IFN-alpha 2a t.i.w. for 6 months (Group B). RESULTS: The sex, age, baseline serum bilirubin, ALT and aspartate aminotransferase (AST) levels were matched in both groups. At the end of the 6th month, the complete and partial response rates in Group A were 60.0% and 16.7% respectively, and the clearance of serum HCV-RNA was 53.3%. In Group B, the complete and partial response rates were 72.7% and 6.1% respectively, and the clearance of HCV-RNA was 61.3%. The patients were followed up for 6, 12, and 18 months after stopping treatment. In Group A, the rates of complete normalization of ALT and clearance of serum HCV-RNA at 24 months were 50.0% and 60.0% respectively. In Group B, the rates of normalization of ALT and clearance of HCV-RNA at 24 months were 54.4% and 41.9% respectively. The efficacy between the two groups showed no statistically significant difference. The response rates of treatment were similar to those in the patients with HCV genotype 1b and 2a. Six patients (10.8% of the study population) developed neutralization antibodies to IFN-alpha 2a during treatment, and four of them were responded to the treatment. Adverse drug reactions (ADR), were common, but most of them were tolerable, and the incidence of ADR was in both groups, but the severity was higher in Group A. CONCLUSIONS: IFN-alpha 2a is effective in the treatment of Chinese patients with chronic hepatitis C. The sustained response rates and adverse drug reactions among two dose schedule groups are similar.

Adolescent↗
PubMed1998

[The relationship between expression of extracellular matrix and clinical pathology of primary lung carcinoma].

OBJECTIVE: To study the relationship between expression of laminin (LN), fibronectin (FN), collagen IV (Col. IV) and clinical pathology of primary lung cancer. METHODS: LSAB method was used to detect the expression of LN, FN and Col. IV in 184 cases of lung carcinoma. RESULTS: Expression of LN and Col. IV in well and moderately differentiated pulmonary squamous cell carcinoma were both higher than that in poorly differentiated cases (P < 0.01), and marked difference was found between lymph node positive and negative cases (P < 0.05). Obvious difference in the expression of LN and Col. IV was found between the patient groups with squamous cell carcinoma who died within 1/2 year and those surviving more than 5 years (P < 0.01), as was the difference in expression of FN (P < 0.05). Obvious difference in the expression of FN and Col. IV was found between patients groups with adenocarcinoma who died within 1/2 year and those surviving more than 5 years (P < 0.05, 0.01). CONCLUSIONS: The expression of LN and Col. IV correlated with histological grading and lymph node metastasis of pulmonary squamous cell carcinoma; LN, FN, Col. IV can also be regarded as a parameter for evaluating prognosis of pulmonary squamous cell carcinoma. The expression of FN and Col. IV can be regarded as a parameter for evaluating the prognosis of pulmonary adenocarcinoma.

Adenocarcinoma↗
PubMed1998

[A study on the nutrient physiology of Ophiopogon japonicus (Thunb.) Ker-Gawl].

By means of observing at regular intervals and on tixed plants, the growth stages, organogenetic habits, content of nutrient elements and its changing regularity, storage habit of dry matter, relationship between aerial and subterraneous parts, and fertilizer requirements have been studied for Ophiopogen japonicus.

Drugs, Chinese Herbal↗
PubMed1998

[In vitro sensitivity of oral gram-negative bacteria to the bactericidal activity of defensins].

Oral gram-negative bacteria, including Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Capnocytophaga sputigena, Provotella intermedius, Provotella melaninogenicus, have been associated with destructive periodontal infection. An ultrasensitive antibacterial assay was applied to determine the sensitivity of a battery of oral gram-negative bacteria to the bactericidal effects of the isolated human neutrophil defensins (HNP) and two kinds of rabbit defensins NP1 and NP2. All species tested were killed by HNP, NP1 and NP2 except that porphyromonas gingivalis was resistant to HNP. However, there was strain-to-strain variation in sensitivity. It was concluded that the oral gram-negative bacteria were sensitive to the cidal mechanism involved in defensinmediated bacterial killing.

Aggregatibacter actinomycetemcomitans↗
PubMed1998

[Ultrastructure of Schistosoma japonicum sperm].

AIM: To understand the ultrastructure of Schistosoma japonicum sperm. METHODS: Testis and oviduct were cut from male and female of S. japonicum respectively, location was assured by observing with microscope. Specimens preparation for transmission electron microscope were made by traditional way. RESULTS: The sperm of S. japonicum includes two parts: a head and a single tail. The elongated ovoid head measures by 6.2 x 1.4 microns, lacking an acrosome, rounding anteriorly and tapering posteriorly. A prominent anterior mass of mitochondria lies beneath the plasma membrane. A layer of microtubes under the plasma membrane are parallel with long axis of the head. A coil of longitudinal microtubes were present beneath the plasma membrane. The nucleus is largely electron-opaque with some electron-lucent patches or less electrondense material. The tail is a single flagellum with a unique axoneme, which originated from a centriole. The axoneme in main part of the flagellum (including middle and posterior parts of the tail) consists of nine doublets and a single diffuse central structure, forming 9 x 2 + <<1>> type. But the axoneme in the transition area (anterior part of the tail) lacks central material, forming 9 x 2 + 0 type. CONCLUSION: The sperm ultrastructure in the schistosomes is homogeneous, but differs distinctly from those trematodes of other Digenea.

Animals↗
PubMed1998

[Studies on dynamic changes of SOD and MDA in cultured cells from Schistosoma japonicum schistosomula].

AIM: To observe the dynamic changes of superoxide dismutase(SOD) and maldondialdehyde(MDA) in cultured cells from Schistosoma japonicum schistosomula and to explore the degeneration process of cultured cells. METHODS: Pyrogallol method and thiobarbituric acid method were used to determinate the levels of SOD and MDA, respectively, in the cells cultured for 0-54 days. RESULTS: SOD in the cells reached a peak level on d12 of the early stage of culture and then decreased. The MDA levels in the cultures cells ascended gradually, and had two peaks on d18 and d48, during the period of culture. CONCLUSION: The cultured cells from S. japonicum schistosomula degenerated progressively.

Animals↗
PubMed1998

[Determination of total Ca in the lung tissue of rats by FAAS].

Determination of total Ca in the Lung Tissue of Rats by FAAS was described, with a mixed microemulsion consisting of sodium dodecyl sulfate, N-dodecyl, N-dimethyl benzol ammonium bromide and nonyl phenol polyethyeneoxy ether. Comparing the result of the microemulsion FAAS with that of solution FAAS showed that the former was better than the latter in sensitivity, precision, selectivity and linearity of the calibration curve, with a detection limit of 1.92 microg x cm(-3), relative standard deviation of 1.92% (n = 10) and linear regressive coefficient of 0.9998 of the calibration curve over 0-20 microg x cm(-3) calcium. The method was applied to determine calcium amount in the lung tissue of rats, and the results were in accordance with those odtained by the conventional solution FAAS, in which a sample was reduced to ashes at a high temperature.

Analytic Sample Preparation Methods↗
PubMed1998

Protein kinase C does not mediate phenylephrine-induced down-regulation of Madin-Darby canine kidney cell alpha-1B adrenoceptors.

We examined the down-regulation of alpha-1B adrenoceptors in Madin-Darby canine kidney D1 (MDCK) cells with an emphasis on a possible role of protein kinase C. The alpha-1 adrenoceptor agonist phenylephrine (1-100 microM) concentration-dependently down-regulated alpha-1B adrenoceptors in MDCK cells. Down-regulation by 100 microM phenylephrine was detectable after 2 hr and maximal after 8 to 24 hr. The receptor down-regulation was accompanied by a decrease in phenylephrine-stimulated inositol phosphate formation but not by an altered expression of immunodetectable Gq/11 alpha subunits. Even though alpha-1B adrenoceptor and P2 purinergic receptor stimulation promote prostaglandin E2 formation, receptor down-regulation was not prevented by indomethacin (10 microM) treatment but was partly mimicked by treatment with the purinergic receptor agonists adenosine-5'-O-(3-thio)triphosphate and 2-methylthio-ATP (300 microM each). Phorbol-12-myristate-13-acetate (1-100 nM) concentration-dependently down-regulated MDCK alpha-1B adrenoceptors to a greater extent than did phenylephrine. Three protein kinase C inhibitors, H7 (100 microM), staurosporine (100 nM) and KT5926 (1 microM), markedly attenuated receptor down-regulation promoted by phorbol ester but did not affect that by phenylephrine. Two inhibitors of Ca++/calmodulin protein kinase pathways, KT5926 (1 microM) and W-7 (30 microM), also failed to prevent phenylephrine-induced down-regulation of alpha-1B adrenoceptors. We conclude that agonist-induced down-regulation of MDCK cell alpha-1B adrenoceptors is mimicked by a protein kinase C-activating phorbol ester but that the second messenger kinases protein kinase C and Ca++/calmodulin protein kinase do not mediate agonist-induced down-regulation of the alpha-1B adrenoceptor.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1998

Murine alpha1-adrenoceptor subtypes. I. Radioligand binding studies.

Alpha1-adrenoceptors were identified in murine tissues by [3H]prazosin saturation binding studies, with a rank order of cerebral cortex > cerebellum > liver > lung > kidney > heart > spleen, with the spleen not exhibiting detectable expression. Competition binding studies were performed with 5-methylurapidil, BMY 7378, methoxamine, (+)-niguldipine, noradrenaline, SB 216469 and tamsulosin. On the basis of monophasic low-affinity competition by BMY 7378, alpha1D-adrenoceptors were not detected at the protein level in any tissue. On the basis of competition studies with the alpha1A/alpha1B-discriminating drugs, alpha1B-adrenoceptors appeared to be the predominant or even the sole subtype in murine liver, lung and cerebellum, whereas murine cerebral cortex and kidney contained approximately 30% and 50% of alpha1A-adrenoceptors, respectively. The affinities of the various competitors in the murine tissues were quite similar to those reported from other species. The ratio of high- and low-affinity sites for tamsulosin did not in all cases match the percentages of alpha1A- and alpha1B-adrenoceptors detected by the other competitors; however, the low-affinity component of the tamsulosin competition curves was abolished in the cerebral cortex of alpha1B-adrenoceptor knockout mice. Treatment with chloroethylclonidine (10 microM, 30 min, 37 degrees C) inactivated the alpha1-adrenoceptors in all tissues by >75%. When the concentration-dependent inactivation of tissue alpha1B-adrenoceptors (liver) and tissue alpha1A-adrenoceptors (cerebral cortex from alpha1B-adrenoceptor knockout mice) was compared, alpha1A-adrenoceptors were only slightly less sensitive toward chloroethylclonidine than alpha1B-adrenoceptors. We conclude that murine tissues express alpha1A- and alpha1B-adrenoceptors, which are largely similar to those in other species. However, the tissue-specific distribution of subtypes may differ from that of other species.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1997

Studies on the microsomal cytochrome P450s in the livers of carcinogen-resistant and sensitive rats during long-term administration of 3'-methyl-4-dimethylaminoazobenzene.

Time-course studies on the microsomal cytochrome P450s in the livers of carcinogen-resistant (DRH) and sensitive (Donryu) rats were carried out during a long-term administration of 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). Total contents of the microsomal cytochrome P450s were gradually reduced with time in the Donryu rat livers, while those in the DRH rats did not alter significantly under these conditions. The activities of several isoforms of cytochrome P450 (CYP1A1, CYP1A2, and CYP2E1) were determined separately during these experimental periods. However, we could not obtain satisfactory evidence which may explain the different susceptibility to chemical carcinogenic actions in the livers between DRH and Donryu rats. Lower total contents of cytochrome P450s in the Donryu rats during the later stage may be due to the hepatic injuries caused by long-term administration of 3'-Me-DAB.

Animals↗
PubMed1997

Chemopreventive effects of diosmin and hesperidin on N-butyl-N-(4-hydroxybutyl)nitrosamine-induced urinary-bladder carcinogenesis in male ICR mice.

The chemopreventive effects of 2 flavonoids (diosmin and hesperidin) on N-butyl-N-(4-hydroxybutyl)nitrosamine (OH-BBN)-induced urinary-bladder carcinogenesis were examined in male ICR mice. Animals were divided into 11 groups, and groups 1 to 7 were given OH-BBN (500 ppm) in the drinking water for 6 weeks. Groups 2 to 4 were fed diets containing the test compounds (group 2, 1000 ppm diosmin; group 3, 1000 ppm hesperidin; group 4,900 ppm diosmin + 100 ppm hesperidin) for 8 weeks during the initiation phase, while groups 5 to 7 were fed these diets, respectively, for 24 weeks during the post-initiation phase. Groups 8 to 11 were controls, given only the test compounds or untreated basal diets throughout the experiment (weeks 1 to 32). The incidence of bladder lesions and cell-proliferation activity estimated by enumeration of silver-stained nucleolar-organizer-region-associated proteins (AgNORs) and by the 5-bromodeoxyuridine (BUdR)-labeling index was compared among the groups. Feeding of the test compounds, singly or in combination, during both phases caused a significant reduction in the frequency of bladder carcinoma and preneoplasia. Dietary administration of these compounds significantly decreased the AgNOR count and the BUdR-labeling index of various bladder lesions. These findings suggest that the flavonoids diosmin and hesperidin, individually and in combination, are effective in inhibiting chemical carcinogenesis of the bladder, and that such inhibition might be partly related to suppression of cell proliferation.

Administration, Oral↗
PubMed1997

Mutations at codon 249 of p53 gene in human hepatocellular carcinomas from Tongan, China.

Codon 249 (exon 7) of the putative tumor suppressor gene p53 is a mutational hot-spot for hepatocellular carcinoma (HCC) but not other tumors. DNA samples from primary HCC patients from Tongan, an area of high HCC incidence in China (> 40 per 100,000 population), were analyzed for specific mutations in codon 249 of the p53 gene using polymerase chain reaction (PCR)/restriction-digest methods and direct DNA sequencing. Seven of the 21 samples screened were found to have a point mutation at the third base position of codon 249 (AGG to AGT). The result is consistent with previous reports that the G-->T transversion is positively associated with the level of dietary aflatoxin B1 (AFB1) contamination, which has been implicated as one of the risk factors in Tongan area. Of the 7 HCC patients that contained the codon 249 point mutation, one was hepatitis B virus (HBV)-negative. This is only the second documentation of an HCC patient harboring the p53 codon 249 mutation, who was HBV-negative.

Adult↗
PubMed1997

Governing step of metastasis visualized in vitro.

Metastasis is the ultimate life-threatening stage of cancer. The lack of accurate model systems thwarted studies of the metastatic cell's basic biology. To follow continuously the succeeding stages of metastatic colony growth, we heritably labeled cells from the human lung adenocarcinoma cell line ANIP 973 with green fluorescent protein (GFP) by transfection with GFP cDNA. Labeled cells were then injected intravenously into nude mice, where, by 7 days, they formed brilliantly fluorescing metastatic colonies on mouse lung [Chishima, T., Miyagi, Y., Wang, X., Yang, M., Tan, Y., Shimada, H., Moossa, A. R. & Hoffman, R. M. (1997) Clin. Exp. Metastasis 15, 547-552]. The seeded lung tissue was then excised and incubated in the three-dimensional sponge-gel-matrix-supported histoculture that maintained the critical features of progressive in vivo tumor colonization while allowing continuous access for measurement and manipulation. Tumor progression was continuously visualized by GFP fluorescence in the same individual cultures over a 52-day period, during which the tumors spread throughout the lung. Histoculture tumor colonization was selective for lung cancer cells to grow on lung tissue, because no growth occurred on histocultured mouse liver tissue, which was also observed in vivo. The ability to support selective organ colonization in histoculture and visualize tumor progression by GFP fluorescence allows the in vitro study of the governing processes of metastasis [Kuo, T.-H., Kubota, T., Watanbe, M., Furukawa, T., Teramoto, T., Ishibiki, K., Kitajima, M., Moossa, A. R., Penman, S. & Hoffman, R. M. (1995) Proc. Natl. Acad. Sci. USA 92, 12085-12089]. The results presented here provide significant, new opportunities to understand and to develop treatments that prevent and possibly reverse metastasis.

Adenocarcinoma↗
PubMed1997

Decreased blood pressure response in mice deficient of the alpha1b-adrenergic receptor.

To investigate the functional role of different alpha1-adrenergic receptor (alpha1-AR) subtypes in vivo, we have applied a gene targeting approach to create a mouse model lacking the alpha1b-AR (alpha1b-/-). Reverse transcription-PCR and ligand binding studies were combined to elucidate the expression of the alpha1-AR subtypes in various tissues of alpha1b +/+ and -/- mice. Total alpha1-AR sites were decreased by 98% in liver, 74% in heart, and 42% in cerebral cortex of the alpha1b -/- as compared with +/+ mice. Because of the large decrease of alpha1-AR in the heart and the loss of the alpha1b-AR mRNA in the aorta of the alpha1b-/- mice, the in vivo blood pressure and in vitro aorta contractile responses to alpha1-agonists were investigated in alpha1b +/+ and -/- mice. Our findings provide strong evidence that the alpha1b-AR is a mediator of the blood pressure and the aorta contractile responses induced by alpha1 agonists. This was demonstrated by the finding that the mean arterial blood pressure response to phenylephrine was decreased by 45% in alpha1b -/- as compared with +/+ mice. In addition, phenylephrine-induced contractions of aortic rings also were decreased by 25% in alpha1b-/- mice. The alpha1b-AR knockout mouse model provides a potentially useful tool to elucidate the functional specificity of different alpha1-AR subtypes, to better understand the effects of adrenergic drugs, and to investigate the multiple mechanisms involved in the control of blood pressure.

Animals↗
PubMed1997

Somatostatin 2A receptor is expressed by enteric neurons, and by interstitial cells of Cajal and enterochromaffin-like cells of the gastrointestinal tract.

Somatostatin exerts multiple effects by activating distinct G protein-coupled receptors. Here we report the cellular sites of expression of the somatostatin subtype 2A (sst2A) receptor in the rat enteric nervous system by using a C-terminus-specific, affinity-purified antiserum and immunohistochemistry. Antibody specificity was confirmed by the cell surface staining of human embryonic kidney 293 cells expressing the sst2A receptor, the lack of staining of cells expressing the somatostatin subtype 2B receptor, and the abolition of staining by preincubating the antiserum with the C-terminus peptide used for immunization, SSt2A(361-369). The SSt2A receptor antibody recognized a broad 80 kDa band on Western blots of membranes prepared from cells transfected with sst2A receptor cDNA; following receptor membrane deglycosylation, the antibody detected an additional 40 kDa band. In the enteric nervous system, the sst2A antibody primarily stained neurons of the myenteric and submucosal plexuses, and abundant fibers distributed to the muscle, mucosa, and vasculature. Immunoreactive staining was also observed in non-neuronal cells, including presumed interstitial cells of Cajal of the intestine and enterochromaffin-like cells of the stomach. Fibers expressing sst2A receptor immunoreactivity were often in close proximity to D cells of the gastric and intestinal mucosa. Colocalization of somatostatin and sst2A receptor immunoreactivities was not observed in endocrine cells nor in enteric neurons. Double-label immunohistochemistry revealed colocalization of sst2A and vasoactive intestinal peptide immunoreactivities in enteric neurons. The multiple types of cells expressing the sst2A receptor, including enteric neurons and non-neuronal structures, in addition to the relationship between somatostatin and sst2A receptor elements, provide evidence that the sst2A receptor mediates somatostatin effects in the gastrointestinal tract via neuronal and paracrine pathways.

Amino Acid Sequence↗