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Biomedical subjects

B Wu

Publications and source records attributed to B Wu.

At least 181 records · Page 10Linked to original sources
PubMed1997

Cloning of a Ca(2+)-ATPase gene and the role of cytosolic Ca2+ in the gibberellin-dependent signaling pathway in aleurone cells.

The ultimate goal of this investigation was to identify intermediary steps in the gibberellin (GA)-dependent signaling pathway in rice aleurone cells. By using a differential display approach, a number of putative GA-responsive genes were isolated. One of them, a GA-responsive Ca(2+)-ATPase gene, was identified and partially characterized. A genomic clone and a cDNA clone were isolated and sequenced. The deduced amino acid sequence showed that this protein resembles an endoplasmic reticulum membrane Ca(2+)-ATPase. In a transient assay in rice aleurone cells, expression of the introduced Ca(2+)-ATPase cDNA bypassed the GA requirement for stimulating the expression of a major target gene, the alpha-amylase c gene (Osamy-c). This result suggests that GA-dependent expression of this Ca(2+)-ATPase gene (OsCa-atpase) plays an important role in the GA-dependent signal-transduction pathway. To investigate the possible involvement of other proteins and genes that may affect the intracellular Ca2+ level, compounds which can block different putative steps in the signal-transduction pathway were introduced into rice aleurone cells, and then the level of the OsCa-atpase transcript or the Osamy-c transcript was monitored. In the presence of GA, the rice Ca(2+)-ATPase and the Ca2+ channels appeared to co-regulate the local concentration of cytosolic Ca2+. The release of Ca2+ from the internal stores to the cytoplasm was presumably initiated by inositol-1,4,5-triphosphate which reached a peak level within 25 min after GA induction. As a second messenger, Ca2+ binds to calmodulin (CaM), and the Ca2+/CaM complex regulates the cytosolic Ca2+ by affecting expression of the OsCa-atpase. Finally, a working model is proposed for the GA-dependent signaling pathway in aleurone cells.

Amino Acid Sequence↗
PubMed1997

Dynamics of maturation-promoting factor and its constituent proteins during in vitro maturation of bovine oocytes.

Maturation-promoting factor (MPF) is known to be a key regulator of both mitotic and meiotic cell cycles. MPF is a complex of a B cyclin and the cyclin-dependent kinase cdkl (p34cdc2). Oocyte maturation and its arrest at metaphase of meiosis II (MII) are regulated by changes in MPF activity. In this study, experiments were conducted to examine the dynamics of MPF activity and its constituent proteins during in vitro maturation of bovine oocytes. Bovine oocytes displayed relatively low levels of MPF (histone H1 kinase) activity at the germinal vesicle stage during the first 8 h of maturation. MPF activity increased gradually thereafter, and its first peak of activity occurred at 12-14 h of maturation (presumptive metaphase I), which was followed by an abrupt reduction in activity at 16-18 h, during presumptive anaphase and telophase. MPF activity then increased, reaching a plateau at 20-24 h of maturation (MII stage). This high level of MPF activity was maintained for several hours but decreased gradually after 30 h of maturation and became barely detectable by 48 h of in vitro maturation (IVM) culture. At each time point, there was a significant variation among individual oocytes in histone H1 kinase activity, which was probably due to asynchronous maturation. Abundance of cdk1 increased gradually during the first 8 h and then remained relatively constant except for an apparent reduction at 18-22 h of IVM. The level of cyclin B2 increased quickly during the initial 2 h of culture, and this high level was maintained until 16 h, after which a significant reduction was observed between 18 and 22 h of IVM. The de novo synthesis of cyclin B2, however, exhibited a biphasic oscillation during maturation, with peaks before the onset of MI and of MII. These results have defined the profiles of MPF activity and its individual components during bovine oocyte maturation in vitro. We conclude that active MPF regulates bovine oocyte maturation and that de novo synthesis of cyclin B2 occurs during the process of maturation.

Animals↗
PubMed1997

Expression of Mos proto-oncoprotein in bovine oocytes during maturation in vitro.

The c-mos proto-oncogene product Mos is believed to be an active component of the cytostatic factor that stabilizes and sustains the activity of maturation-promoting factor. Mos has been found to be responsible for the metaphase arrest of oocytes at the second meiotic division in both Xenopus and the mouse. In this study, we have demonstrated, by Western blot and immunoprecipitation analysis, that an approximately 39-kDa protein, identified as Mos, was present in in vitro-matured (metaphase II stage) bovine oocytes but disappeared in parthenogenetically activated oocytes. The oocytes actively synthesized p39mos at the metaphase II stage (between 22 and 26 h of in vitro maturation [IVM]), whereas little p39mos synthesis was detected during the first 4 h of IVM and it was nondetectable during aging at 44-48 h of IVM, when oocytes lose the capability of normal development after fertilization. Ethanol activation of mature oocytes led to the disappearance of p39mos. beta-Tubulin, but not p34cdc2, was co-precipitated with Mos when extracts of metaphase II-stage bovine oocytes were incubated with Mos antiserum. These results demonstrated that Mos is present and actively synthesized in mature bovine oocytes and that oocytes aged beyond the optimal time for fertilization seem to lose the ability to synthesize the Mos protein. beta-Tubulin was found to be associated with Mos, which suggests a possible role for the cytoskeletal protein in maintaining the meiotic arrest in mature bovine oocytes.

Amino Acid Sequence↗
PubMed1997

Cerebral blood flow during hypoxemia and hemodilution in rabbits: different roles for nitric oxide?

Hypoxemia and anemia are associated with increased CBF, but the mechanisms that link the changes in PaO2 or arterial O2 content (CaO2) with CBF are unclear. These experiments were intended to examine the contribution of nitric oxide. CaO2 in pentobarbital-anesthetized rabbits was reduced to approximately 6.5 mL O2/dL by hypoxemia (PaO2 approximately 24 to 26 mm Hg) or hemodilution with hetastarch (hematocrit approximately 14% to 15%). Animals with normal CaO2 (approximately 17.5 to 18 mL O2/dL) served as controls. In part I, each animal was given 3, 10, and 30 mg/kg N omega-nitro-L-arginine methyl ester (L-NAME) intravenously (total 43 mg/kg) to inhibit production of nitric oxide. Forebrain CBF was measured with radioactive microspheres approximately 15 to 20 minutes after each dose. Baseline CBF was greater in hypoxemic rabbits (111 +/- 31 mL x 100 g-1 x min-1, mean +/- SD) than in hemodiluted (70 +/- 22 mL x 100 g-1 min-1) or control animals (39 +/- 12 mL x 100 g-1 min-1). L-NAME (which reduced brain tissue nitric oxide synthase activity by approximately 65%) reduced CBF in hypoxemic animals to 80 +/- 23 mL x 100 g-1 x min-1 (P < 0.0001), but had no significant effect on CBF in either anemic or control animals. In four additional rabbits, further hemodilution to a CaO2 of approximately 3.5 mL O2/dL increased baseline CBF to 126 +/- 21 mL x 100 g-1 min-1, but again there was no effect of L-NAME. In part II, animals were anesthetized as above, and a close cranial window was prepared. The cyclic GMP (cGMP) content of the artificial CSF superfusate was measured under baseline conditions, and then after the reduction of CaO2 to approximately 6.5 mL O2/dL by either hypoxemia or hemodilution. Concentrations of cGMP did not change during either control conditions or after hemodilution. However, cGMP increased significantly with the induction of hypoxemia. The cGMP increase in hypoxemic animals could be blocked with L-NAME. These results suggest that nitric oxide plays some role in hypoxemic vasodilation, but not during hemodilution.

Animals↗
PubMed1997

A 120 kilobase resolution contig map of the rice genome.

92% of the rice genome (4.3 x 10(8) bp, 2n = 24) was covered by 631 contigs of various length, which were generated by fingerprinting from a representative and genetically stable bacterial artificial chromosome (BAC) library of the Guang Lu Ai 4 (a O. Sativa variety) genome with the average insert of 120 kb in length. To form the contig map, 565 molecular markers of RFLP, STS, cDNA and anchor set derived from two O. Sativa varieties were by colony hybridization mapped to the contigs, which were then assigned to and ordered along the particular chromosomes according to the marker colinearity. Being highly conserved DNA sequences shared among the genomes of rice, barley, wheat, oat, maize, sorghum and sugar cane, 89 anchor markers mapped help to identify the rice genes through the information provided by the maps of relative genomes, and vice versa. Numerous repeated DNA sequences of various length were identified and mapped to the chromosomes. Physical distances have been determined for hundreds pairs of adjacent markers, which would facilitate the identification by map-based cloning the rice genes of interest. The accuracy of clone overlaps in contigs was further confirmed by the existence in contigs of well fit stacks of marker-lodged clones independently identified by hybridization. Large scale DNA sequencing of individual chromosomes could now be initiated simply by selecting and sequencing the minimally overlapped BAC clones of the contigs.

Alkyl and Aryl Transferases↗
PubMed1997

[Mutation and methylation of CDKN2 gene in human head and neck carcinomas].

OBJECTIVE: To study mutations of CDKN2 gene in human head and neck carcinomas (HNC) and to elucidate the role of this gene in tumorigenesis. METHODS: PCR-SSCP and sequencing techniques were used to detect mutations in fresh specimens from 36 HNC cases. Specimens from 20 cases were further analysed for methlyation status of the CpG islands in the first exon of the gene using restriction enzyme digestion plus Southern blotting analysis. RESULTS: CDKN2 gene mutations were detected in 4 HNC cases of which 2 were missense mutation and the other 2 were frameshift mutation. Methylation status analysis revealed that 8 out of 20 HNC cases had de novo methylation of CpG island within the first exon of CDKN2 gene. CONCLUSION: The results shown here suggest that in addition to gene mutation and deletion, de novo methylation of the CpG island may be a frequent event in human carcinogenesis.

Carcinoma, Squamous Cell↗
PubMed1997

[The inhibitory effect of antisense interleukin-6 on the growth of human lung carcinoma cells in vivo].

OBJECTIVE: Interleukin-6 (IL-6) has previously been implicated as a potential positive autocrine regulator of a human lung carcinoma cell lince PG. The purpose of the present study is to further evaluate the role of IL-6 in PG cells in vivo. METHODS: An antisense expression vector for IL-6 was constructed and introduced into PG cells. Antisense mRNA of IL-6 was detected by RNA-RNA dot blotting analysis. The production of bioactive IL-6 was measured by bioassay method. To determine the effect of antisense IL-6 cDNA on tumorigenicity, PG cells were inoculated subcutaneously into nude mice. RESULTS: Four transfectants, PGTAS1, PGTAS6, PGTAS8, PGTAS9, could express IL-6 antisense mRNA and secret decreased bioactive IL-6. The growth rate of 4 transfectants revealed was reduced in vitro. Comparing with the mice injected with the control PGTneo cells, the latent period of the mice inoculated with PGTAS6, PGTAS8, PGTAS9 cells was significantly increased, and the growth rate of the tumors was obviously decreased. The tumor size was markedly smaller. There was a negative correlation between the growth-inhibiting effect of IL-6 antisense gene and the amount of IL-6 secretion. CONCLUSION: These results indicate that IL-6 can function as an autocrine stimulator for PG cells in vivo as well as in vitro.

Animals↗
PubMed1997

Effect of epidermal growth factor on cultured rat hepatocytes poisoned by CCl4.

AIM: To study the effects of epidermal growth factor (EGF) on CCl4-induced primary cultured hepatocytes injury. METHODS: Alanine amino-transferase (AlaAT) and aspartate aminotransferase (AspAT) activities and K+ concentractions were determined by the Auto-biochemistry Assay System. Malondialdehyde (MDA) was determined by thiobarbituric acid method. Radioactivity was determined by liquid scintillometry. Light microscopy and electron microscopy were used. RESULTS: EGF 40 micrograms.L-1 decreased CCl4 (10 mmol.L-1)-induced damages of rat primary cultured hepatocytes by decreasing AlaAT and AspAT leakage and MDA production, and promoted RNA and DNA synthesis, with a high positive correlation between intracellular K+ leakage and DNA syntheses (r = 0.99, P < 0.01). Cytopathological study showed that EGF decreased damage of liver cells. CONCLUSION: EGF maintains the stability of cellular lipid membrane and promotes syntheses of RNA and DNA of hepatocytes, and intracellular K+ transference is a promotor of the message transmission of DNA synthesis.

Alanine Transaminase↗
PubMed1997

[Protective effects of 15-methyl-prostaglandin F2 alpha on primary cultured rat hepatocyte against CCl4-induced injury].

The effect of 15-Mt-PGF2 alpha on CCl4-induced injury of primary cultured hepatocytes was studied. 15-Mt-PGF2 alpha treatment (2 mg/L) significantly decreased CCl4 (10 mmol/L)-induced damages of primary cultured rat heptocytes as indicated by decreases GPT and GOT leakage and LPO production. 15-Mt-PGF2 alpha significantly promoted 3H-uridine incorporation into RNA and [3H]-thymidine incorporation into DNA of the rat hepatocytes. Cytopathology study showed that 15-Mt-PGF2 alpha attenuated damages of mitochondria, endoplasmic reticulum and ribosome caused by CCl4. 15-Mt-PGF2 alpha appeared to maintain the stability of rat hepatocytes by inhibiting lipid peroxidation. These results indicated that 15-Mt-PGF2 alpha has notable protective effect on primary cultured rat hepatocytes against CCl4-induced damage by reducing lipid peroxidation and promoting synthesis of RNA and DNA.

Animals↗
PubMed1997

[DNA content correlation with the prognosis of pheochromocytoma: 10 cases report].

We investigated the relationship between DNA ploidy and the prognosis of pheochromocytoma. DNA ploidy studies on paraffin-embedded archival specimens from ten cases of pheochromocytoma were performed by flow cytometry according to Hedley's method. Clinical features and pathological results were investigated and follow-up was made. The values of DNA content in assessment of the prognosis of the tumor were discussed. Flow cytometry examination showed that seven cases had aneuploid, two deploid and one tetraploid. The malignent case was tetraploid, and died from matastasis to the bone. The other cases had a benign process. The examination of DNA content is of value in the assessment of the prognosis of pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1997

[Applied anatomy of the submental island flap].

To observe the anatomy of the island flap based on the submental vessels for clinical applications, the blood supply in the submental region was studied on 51 cadavers by microsurgical dissection and dye injection. It was found that the submental region is supplied by the submental artery, which is a constant branch of the facial artery (100% rate of occurrence). The vessel was 60.0 +/- 7.9 mm in length with a diameter of 1.75 +/- 0.15 mm (mean +/- s) at its origin. There were rich anastomoses between submental arteries of both sides. Based on the reliable pedicle, the flap dimension can be as large as 130 mm x 65 mm.

Adult↗
PubMed1997

[R wave relative oscillometric blood pressure measurement].

To improve the accuracy of oscillometric blood pressure measurement, an artifact rejection method for oscillations detection called R wave-relative method was developed. It was mainly based on the correlation between ECG R wave and oscillation. Combining with identification of oscillation characteristics this method can distinguish valid signals from interference. This algorithm has been implemented in 8098 microcontroller. Its program flowchart has also been presented in this paper.

Algorithms↗
PubMed1997

[Preliminary study on method for predicting lower body negative pressure tolerance].

To find out a method to predict lower body negative pressure (LBNP) tolerance with noninvasive physiological measurements, 11 healthy young subjects were tested in an LBNP chamber in sitting position. Incremental negative pressure was used for evaluating LBNP tolerance time. End points of the test were onset of presyncopal symptoms or completion of 15 min test. According to their reactions, the 11 subjects were divided into good tolerance group (group A, n = 5) and poor tolerance group (group B, n = 6); At the 11th minute of LBNP, mean arterial pressure (MAP), magnitude of decrease of regional cerebral oxygen saturation (delta SrO2) and cardiac output (delta CO) showed significant difference between group A and B(P <0.05); Mean error was 0.54 +/- 0.42 min when LBNP tolerance was predicted using MAP and delta SrO2 at this moment by regression analysis.

Aerospace Medicine↗
PubMed1997

Changes of cerebral oxygen saturation under lower body negative pressure.

The purpose of this study was to observe and analyse the changes of regional cerebral oxygen saturation (SrO2) under lower body negative pressure (LBNP). 12 healthy young subjects were tested in an LBNP chamber in sitting position. Incremental negative pressure was used and end points of test were onset of presyncopal symptoms or completion of the 15min test. The results were: (1) SrO2 showed a significant decrease under LBNP; (2) The magnitude of decrease of SaO2 showed significant differences among subjects with different reactions at the termination of LBNP; (3) Under LBNP the arterial oxygen saturation (SrO2) kept constant. The changes of SrO2 correlated strongly with the percentage changes of superaorbitalis arterial blood flow (r = 0.59-0.86, P < 0.05 or 0.01). It was suggested that the changes of SrO2 were related to the decrease of cerebral blood flow under LBNP. It was possible to use SrO2 to detect presyncopal and syncopal symptoms. So the monitoring of SrO2 could be used in studies of G-LOC.

Adult↗
PubMed1997

Inhibition of nitric oxide synthesis during severe shock but not after resuscitation increases hepatic injury and neutrophil accumulation in hemorrhaged rats.

Hemorrhagic shock results in hepatocellular dysfunction and hepatic injury that may contribute to the development of liver failure and multiple organ dysfunction in trauma patients. The specific mediators involved in this process remain incompletely defined. We have previously demonstrated that inhibition of nitric oxide (NO) synthesis in a rat model of moderately severe hemorrhagic shock increases hepatic injury, suggesting that NO synthesis is beneficial after hemorrhage. To further define the role of NO in hepatic function during hemorrhagic shock, rats were subjected to a severe hemorrhagic shock insult in which they were bled to a mean arterial pressure of 40 mmHg until 40% of their shed blood had been returned and then were resuscitated. Rats were treated with the NO synthase inhibitor L-nitroarginine methyl ester (L-NAME) or the NO donor S-nitroso-N-acetylpenicillamine beginning either during the hypotensive period or after resuscitation. When instituted during the hypotensive period, low dose L-NAME infusion significantly increased hepatic injury. When L-NAME was infused after resuscitation, no increase in hepatic injury was detected even when the L-NAME dose was increased by a factor of four. The increased hepatic injury produced by L-NAME was associated with increased myeloperoxidase content in the lung, suggesting that L-NAME led to a greater accumulation of neutrophils during shock. Administration of the NO donor S-nitroso-N-acetylpenicillamine reduced hepatocellular enzyme release. Our results suggest that ongoing NO synthesis during the hypotensive phase of hemorrhagic shock is essential in preventing shock-induced hepatic injury and this may be due, in part, to the interaction between NO and circulating neutrophils.

Alanine Transaminase↗
PubMed1997

[Causes of active phase arrest].

OBJECTIVE: To evaluate factors affecting active phase arrest. METHOD: Retrospective study from 1992 to 1994 was performed. A total of 166 pregnant women were included, 83 in to the active phase arrest group and 83 in normal group. RESULTS: There were significant differences in the average birth weight and the prevalence of abnormal fetal presentation between the 2 groups. The time length of the latent phase was another factor influencing active phase arrest. CONCLUSION: With normal pelvis, the high birth weight, abnormal presentation and prolonged latent phase were active phase arrest.

Adult↗