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Biomedical subjects

G J Wu

Publications and source records attributed to G J Wu.

At least 37 records · Page 2Linked to original sources
PubMed1999

Localization of PS6K to chromosomal region 17q23 and determination of its amplification in breast cancer.

The application of comparative genomic hybridization to the analysis of genetic abnormalities in breast carcinoma has consistently revealed that chromosome region 17q22-24 is a frequent site of gene amplification in this type of cancer. As part of an examination of expressed sequence tags for novel amplified genes in this region, we identified PS6K amplifications in both breast tumor tissues and cell lines. PS6K was localized to 17q23 and encodes a serine-threonine kinase whose activation is thought to regulate a wide array of cellular processes involved in the mitogenic response including protein synthesis, translation of specific mRNA species, and cell cycle progression from G1 to S phase. Northern and Western analyses revealed that amplification of this gene was accompanied by corresponding increases in mRNA and protein expression, respectively. These data represent the first determination of a gene amplification within 17q22-24 in breast cancer and suggest an oncogenic activity for PS6K.

Breast Neoplasms↗
PubMed1999

Identification of core sequences involved in metabolism-dependent nuclear protein binding to the rat insulin-like growth factor I gene.

In the liver, most insulin-like growth factor I (IGF-I) transcripts originate in exon 1, where important cis-regulatory regions are located downstream from the major transcription initiation sites. Within these regions, we have attempted to identify sequences which are involved in the decrease in IGF-I gene transcription associated with diabetes mellitus. The function of different genomic templates was assessed by in vitro transcription, which revealed a consistent 50-80% decrease in the activity of nuclear extracts from streptozotocin-diabetic as compared with normal rats. The disparity in transcriptional activity between normal and diabetic nuclear extracts was reduced with templates containing 11-bp mutations within DNase I protected regions III or V (+42 and +129 bp, respectively, from the major transcription initiation site), but a mutation between regions IV and V had little effect. Within region III, gel mobility shift analysis and methylation interference studies indicated that DNA-protein interactions involve a GCGC core sequence. In region V, gel mobility shift studies and uracil interference analysis revealed interactions involving a TTAT core. While gel mobility shift analysis and transient transfection studies indicate that the GCGC core sequence in region III recognizes C/EBP, the AT-rich sequence in region V is likely to recognize a protein with homeodomain characteristics. Identification of the nuclear factor(s) interacting with regions III and V, downstream from exon 1 initiation sites, will be important for understanding the mechanism of reduced IGF-I gene transcription due to diabetes mellitus.

Animals↗
PubMed1999

[Opioid mu receptors in caudate nucleus contribute to electroacupuncture and Sm I generating inhibition on nociceptive responses of Pf neurons].

The present experiments aimed to investigate whether the caudate nucleus (Cd) was involved in cortical sensorimotor area I (Sm I) generating descending modulation of the parafascicular nucleus (Pf) in acupuncture analgesia (AA), and what type of opiate receptors in Cd were involved. It was found that nociceptive responses of Pf neurons could be inhibited by electroacupuncture (EA) and excitation of Sm I before lesion of Cd, but not after lesion. After microinjection of naloxone beta-FNA, the specific antagonist for opioid mu receptors, into Cd,the inhibitory effect of EA or activation of Sm I on nociceptive responses of the Pf neurons was abolished, but it was not influenced by microinjection of nor-BNI and ICI174,864, the specific antagonists for opioid kappa and delta receptors, respectively. Together with our previous findings that EA could activate cortical neurons to participate in descending modulation of activities of Pf neurons, the present results suggest that Cd is associated with Sm I generating descending inhibition on nociceptive responses of Pf neurons in AA, and it is most likely that opiates in Cd may be involved in this inhibition through mu but not kappa or delta receptors.

Acupuncture Analgesia↗
PubMed1998

A protein encoded by din1, a dark-inducible and senescence-associated gene of radish, can be imported by isolated chloroplasts and has sequence similarity to sulfide dehydrogenase and other small stress proteins.

In an attempt to isolate cDNA clones for dark-inducible chloroplast proteins, we screened a cDNA library which was prepared from radish cotyledons by a two-step method. The source plants were grown under continuous light for 14 d and kept in darkness for 24 h. One of the selected clones, S2D12, corresponded to the din1 gene which we previously reported as a dark-inducible, senescence-associated gene [Azumi and Watanabe (1991) Plant Physiol. 95:577]. A 22 kDa polypeptide was produced from the cDNA in an in vitro expression system in the presence of [35S]methionine. This polypeptide was capable of being imported by isolated chloroplasts, processed to a smaller mature form and localized in the stromal fraction. As the amino acid sequence of the putative mature protein has no homology to any known chloroplast protein, din1 was suggested to be the first gene for a chloroplast protein which is negatively controlled by light. The putative mature protein has similarity to sulfide dehydrogenase from Wolinella succinogenes and other small stress proteins; glpE and pspE from Escherichia coli and hsp67B2 from Drosophila melanogaster.

Amino Acid Sequence↗
PubMed1998

[Assignment of a novel zinc finger gene ZNF191 to human chromosome 18Q12.1 by human/rodent somatic cell hybrid panel and fluorescent in situ hybridization].

A novel human zinc finger gene, ZNF191, was assigned to chromosome 18 by hybridization of human/rodent hybrid cell panel to a full-length cDNA as a probe. Meanwhile, a human genomic DNA lambda/DASH library was screened using this cDNA probe and several positive clones were obtained. Fluorescence in situ hybridization (FISH) was performed by using one of these positive clones, 16-1, as a probe. Thus, the ZNF191 gene was precisely mapped in 18q12. 1. To date, some hereditary diseases and tumors have been found to be associated with this region by analysis of genetic linkage and loss of heterozygosity. Hence, it suggested that the gene ZNF191 can be taken as a candidate gene responsible for those diseases and tumors.

Chromosome Mapping↗
PubMed1998

[Isolation of novel expression sequences of C2H2 type zinc finger protein gene from human brain tissue according to the conservation of zinc finger motif].

By low stringency PCR amplification of genomic DNA using the primers designed based on the conservation of zinc finger motif, we got 8 gradient eletrophoretic bands. After recovery of the second and third bands, the DNA fragments in them were cloned and sequenced. Compared to the GenBank database, among these 60 segments containing zinc finger motif, 23 segments were novel zinc finger genes' genomic segments. Then the human brain tissue cDNA library was screened, using these segments as probes, and 44 positive clones were obtained. Rescreening 28 of them, we got 20 rescreened clones. All of them were sequenced and sent to the GenBank DNA database for sequence analysis, the results showed that 16 were novel C2H2 type zinc finger protein cDNA segments. The cDNA segments encoding the novel C2H2 type zinc finger proteins provide the basic materials for cloning of full length cDNA of valuable novel zinc finger protein genes.

Amino Acid Sequence↗
PubMed1997

Metabolic characteristics and enflurane defluorination of cytochrome P450-dependent monooxygenases in human hepatocellular carcinoma.

BACKGROUND: Xenobiotic metabolism and defluorination capacity of microsomal monooxygenases were investigated in vitro through the surgical specimens of liver resected from patients with hepatocellular carcinoma and patients of extrahepatic pathology as control. METHODS: In microsomes of hepatocellular carcinoma tissues, the activities of cytochrome P450-dependent monooxygenase isoenzymes 1A1, 2B1, and 2E1 were evaluated in vitro by reacting with the specific marker substrates benzo(a)pyrene, benzphetamine and aniline, respectively, in the generating incubation system. The distant normal liver tissues and tissues from control patients with extrahepatic lesion were also investigated for comparison. The ability of enflurane defluorination was assessed by Orion combined for detection of free fluoride ion production. RESULTS: Concentrations of P450 total content, cytochrome b5, and NADPH-cytochrome c reductase showed parallel and marked reduction in tumor tissues when compared with its distant normal regions or normal livers. The monooxygenase functions displayed significant decreases within the tumor tissues as benzo(a)pyrene hydroxylation > or = benzphetamine demethylation > aniline hydroxylation in magnitude. Defluorination of enflurane also markedly decreased in tumor tissues comparing with normal livers. CONCLUSIONS: These marked reductions in the compositions and in vitro metabolic activities, including defluorination of anesthetics, in the cytochrome P450-dependent monooxygenases within the tumor tissues characterize the unique pattern of xenobiotic metabolism in patients with hepatocellular carcinoma.

Aged↗
PubMed1996

Microtubule and chromatin dynamics during fertilization and early development in rhesus monkeys, and regulation by intracellular calcium ions.

To explore primate fertilization, oocytes and zygotes from fertile rhesus monkeys were imaged throughout fertilization, polyspermy, and artificial activation using confocal microscopy for microtubules and DNA, as well as ratiometric computer-enhanced video microscopy for intracellular calcium. Unfertilized oocytes displayed microtubules only in the radially oriented meiotic spindles. At insemination, a large calcium transient was followed by a series of smaller oscillations, and sperm astral microtubules had assembled from the sperm centrosome by 2.5 h after transient onset. This aster enlarged, and later duplicated, as the pronuclei converged near the cortex. Pronuclear apposition was prevented by microtubule inhibitors. At mitotic prophase, microtubules ensheathed both sets of condensing chromosomes. At metaphase, the spindle was barrel-shaped and eccentrically positioned with two small asters at the pole with the sperm tail. Microtubules emanating from the telophase spindle interacted with the adjacent cortex and displaced the spindle toward the cell center as first cytokinesis ensued. During polyspermy, each sperm nucleated an aster, and the frequency of calcium oscillations increased. Activation resulted initially in disarrayed microtubules that eventually organized into functional mitotic spindles. These kinetic results demonstrate that rhesus monkeys accomplish fertilization in a fashion nearly identical to that of humans and are, therefore, ideal models in which to investigate cytoskeletal events during human reproduction.

Adenine↗
PubMed1995

Transcriptional regulation of the rat insulin-like growth factor-I gene involves metabolism-dependent binding of nuclear proteins to a downstream region.

Insulin-like growth factor-I (IGF-I) gene transcription is mediated largely via exon 1. In an initial search for regulatory regions, rat hepatocytes were transfected with IGF-I constructs. Since omission of downstream sequences led to reduced expression, we then used in vitro transcription to evaluate potential metabolic regulation via downstream regions. With templates including 219 base pairs of downstream sequence, transcriptional activity was reduced 70-90% with hepatic nuclear extracts from diabetic versus normal rats. However, activity was comparable with templates lacking downstream sequences. The downstream region contained six DNase I footprints, and templates with deletion of either region III or V no longer provided reduced transcriptional activity with nuclear extracts from diabetic rats. Nuclear protein binding to regions III and V appeared to be metabolically regulated, as shown by reduced DNase I protection and activity in gel mobility shift assays with nuclear extracts from diabetic rats. Southwestern blotting probes corresponding to regions III and V recognized a approximately 65-kDa nuclear factor present at reduced levels in diabetic rats. These findings indicate that a downstream region in exon 1 may be important for both IGF-I expression and metabolic regulation. Altered concentration or activity of a transcription factor(s) binding to this region may contribute to reduced IGF-I gene transcription associated with diabetes mellitus.

Animals↗
PubMed1995

The paternal inheritance of the centrosome, the cell's microtubule-organizing center, in humans, and the implications for infertility.

Successful fertilization in humans, achieved when parental chromosomes intermix at first mitosis, requires centrosome restoration and microtubule-mediated motility. Imaging of inseminated human oocytes reveals that the sperm introduces the centrosome. The centrosome then nucleates the new microtubule assembly to form the sperm aster--a step essential for successful fertilization. Oocytes from some infertile patients failed to complete fertilization because of defects in uniting the sperm and egg nuclei, indicating that failure to properly effect the cytoplasmic motions uniting the nuclei results in human infertility. These discoveries have important implications for infertility diagnosis and managing reproduction.

Centrosome↗
PubMed1994

Transcription function of each base pair in the control region of the adenovirus VARNA1 gene.

Eighty-seven mutants with single-base substitution in the control region (from -44 to +70) of the adenovirus VARNA1 gene were generated, including nearly every base pair, to examine the role of DNA sequences within this control region for regulating transcription. The effect of these mutations on transcription of the gene was determined in vitro using cytoplasmic S100 extracts from human KB cells. Mutations at -37T, -35A, -29T, -28A, -25C, -18A, -17A, -16A, -13A, -9C, -8C, and -1C in the 5'-flanking region reduced transcription of the gene. Thus two positive regulatory elements, from -44 to -25 and from -18 to +2, interspersed with a putative negative regulatory element were defined. Furthermore, a distinct A-rich purine stretch in the -18 to +2 element was identified. Point mutations in the pyrimidine-rich sequence immediately upstream of the A block promoter element reduced transcription of the gene. Mutations in the GTGG direct repeats of the A block promoter element drastically decreased transcription. Furthermore, mutations that altered the AT-rich sequence immediately downstream of the A block element to become less AT-rich decreased transcription. Mutations of the base pairs at +43C, +45T, and +51A in the inter-block element moderately reduced transcription efficiency of the gene. Mutations at the central four base pairs, GTTC, of the B block palindrome severely affected transcription. These unique sequence motifs and their exact base pairs were proven to be important for regulating transcription of the VARNA1 gene.

Adenoviruses, Human↗
PubMed1994

Clinical implications and factors related to left atrial spontaneous echo contrast in chronic nonvalvular atrial fibrillation.

The mechanisms leading to formation of spontaneous echo contrast (SEC), a smoke-like echo on echocardiography, are still controversial. To further explore the clinical implications and factors related to SEC formation, the correlation among echocardiographic variables, hematologic parameters or platelet aggregability, and the occurrence of SEC was studied in 119 patients with chronic nonvalvular atrial fibrillation. There were 75 men and 44 women with a mean age of 65 +/- 10 years (range 38-88). Left atrial SEC was detected in 39 patients (33%) by transesophageal echocardiography. Patients with history of systemic embolism were more frequently found to have left atrial SEC and left atrial thrombus by univariate analysis. Multivariate analysis showed that left atrial SEC (p < 0.001) was the only independent predictor of history of systemic embolism. Age, sex, left atrial or left ventricular dimension, left ventricular ejection fraction, antiplatelet or anticoagulant therapy and the percentage of lone atrial fibrillation were not significantly different between patients with and without left atrial SEC. Among the hematologic parameters, higher hematocrit was found in patients with left atrial SEC, while white blood cell and platelet counts were comparable in both groups. Platelet aggregability with different concentrations of inducers, adenosine diphosphate and collagen, was evaluated by the turbidimetric method in 15 patients with left atrial SEC and in 42 patients without left atrial SEC who were not receiving antiplatelet or anticoagulant therapy. No significant difference was found in platelet aggregability using four inducer concentrations between two groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Recovery from propofol anesthesia: a quantitative electroencephalographic analysis.

Four numerical descriptors (median frequency, spectral edge frequency-95%, total power, and delta-ratio) derived from the computer-processed electroencephalogram (Neurometrics Lifescan) were analyzed for their ability to predict imminent arousal from total intravenous anesthesia with propofol. Fifteen patients undergoing minor surgical procedures without intubation were enrolled in the study. Arousal was defined as eye opening in response to verbal stimuli. During emergence from propofol, there were no significant changes among the descriptors except the delta-ratio. Significant change of delta-ratio occurred 210 seconds before patients' arousal and thereafter. An increase of delta-ratio value indicates that patients shifted from anesthetic to arousal state. It is concluded that the degree of delta-ratio change may be used for predicting patients' arousal from propofol anesthesia.

Adult↗
PubMed1993

Plasma endothelin levels and surgically correctable pulmonary hypertension.

To know the changes in plasma endothelin of patients with pulmonary hypertension, we studied 32 patients with valvular heart disease. Among them, 22 patients had pulmonary hypertension (group I) and 10 had pulmonary arterial pressures in the normal range (group II). Plasma endothelin-1 concentrations of the patients in group I were significantly greater than those of the patients in group II (p < 0.05). No significant difference in plasma endothelin-3 concentrations existed between the two groups. Cardiac output and pulmonary capillary wedge pressure had a linear correlation with plasma endothelin-1 levels. There was also a significant correlation between plasma endothelin-1 levels and hemodynamic indicators of severity of pulmonary hypertension, such as mean pulmonary arterial pressure and pulmonary vascular resistance (p < 0.05). All patients in this study underwent surgical procedures for the correction of valvular lesions. All patients in group I showed a decrease in pulmonary arterial pressures, and their plasma endothelin-1 levels decreased from 3.84 +/- 0.20 pg/mL to 1.66 +/- 0.07 pg/mL (p < 0.05), whereas the plasma endothelin-3 levels had only slight variation from 0.64 +/- 0.11 pg/mL to 0.75 +/- 0.06 pg/mL (p > 0.05) between the preoperative and the postoperative stages. The results demonstrated that plasma endothelin-1 rather than endothelin-3 had a role in pulmonary hypertension. Several pieces of evidence pointed out that endothelin-1 functioned as a reactive mediator during vasoconstriction in the case of pulmonary hypertension rather than as a triggering factor of pulmonary hypertension.

Adolescent↗
PubMed1993

Plasma endothelin level changes during hemorrhagic shock.

The purpose of this study was to analyze changes in plasma endothelin-1 levels during hemorrhagic shock. Thirty-two mongrel dogs were divided into four equal groups with group I as the controls and groups II through IV as experimental groups. The dogs in the experimental groups underwent hemorrhagic procedures. The mean blood pressure was kept at the level of 65 mm Hg in group II, 50 mm Hg in group III, and 40 mm Hg in group IV. Blood samples were collected from each dog under the following conditions: (1) after induction of anesthesia, when the animals were hemodynamically stable, before the start of shock; (2) 1 minute after the mean arterial pressure dropped to the level designed for each group (shock 1); (3) 15 minutes after shock 1; (4) 30 minutes after shock 1; (5) 1 hour after shock 1; (6) 2 hours after shock 1; (7) 4 hours after shock 1; and (8) 8 hours after shock 1. Plasma endothelin-1 levels both in arterial and venous blood were analyzed in each dog. The results showed that (1) arterial endothelin-1 concentrations were considerably lower than venous concentrations at the baseline level; (2) after the shock-1 point, plasma endothelin-1 concentrations increased, first markedly and then evenly throughout the oligemic period; (3) elevation of plasma endothelin-1 levels was significantly linearly correlated with the amount of blood loss at the time of 2 hours after shock and thereafter; (4) the arterial/venous ratio of plasma endothelin-1 levels during the oligemic period was higher than that in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Regulation of insulin-like growth factor-I (IGF-I) and IGF-binding protein 1 gene transcription by hormones and provision of amino acids in rat hepatocytes.

Synthesis of insulin-like growth factor-I (IGF-I) and IGF binding protein-1 (IGFBP-1) is altered in diabetes and malnutrition, but underlying processes are poorly understood. To study molecular mechanisms, we examined regulation of IGF-I and IGFBP-1 gene transcription in primary cultures of rat hepatocytes. Transcription of the IGF-I and IGFBP-1 genes was measured as incorporation of [alpha-32P]UTP into preinitiated message in isolated nuclei. IGFBP-1 gene transcription was not sensitive to reduction in amino acid concentration from 5x to 0.5x rat arterial plasma levels. However, IGF-I gene transcription fell 60-70% in response to reduced provision of amino acids. Culture with 10(-9) M insulin lowered IGFBP-1 gene transcription 50% below control levels (10-11 M) but did not affect IGF-I gene transcription; 10(-6) M insulin raised IGF-I gene transcription 2-fold. After an acute reduction in insulin concentration, IGFBP-1 transcription began to rise within 30 min, but IGF-I gene transcription was unchanged over 120 min. Similarly, 3-6 h were required for stimulation of IGF-I gene transcription by insulin, but a 40% decrease in IGFBP-1 gene transcription could be detected within 15 min after adding 10(-6) M insulin, and suppression of IGFBP-1 transcription by insulin was unaffected by the presence of cycloheximide. Effects of insulin on IGFBP-1 gene transcription were not mimicked or antagonized by phorbol ester.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗