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Biomedical subjects

D Wu

Publications and source records attributed to D Wu.

At least 505 records · Page 28Linked to original sources
PubMed1993

Role of mu 1- and delta-opioid receptors in modulation of fetal EEG and respiratory activity.

Recent evidence suggests that administration of low doses of morphine causes respiratory stimulation, along with a more active electroencephalogram (EEG) in the fetal lamb. The present study used selective opioid agonists and antagonists to determine the role mu 1- and delta-opioid receptor subtypes play in the response as well as determine if endogenous opioid peptides exert a tonic influence at the mu 1- and delta-opioid receptors to maintain normal EEG and respiratory activity under control, physiological conditions. Both morphine (2.5 mg/h iv) and [D-Pen2,D-Pen5]enkephalin (DPDPE) (46 nmol/h icv) resulted in a significant activation of fetal EEG, which was blocked by naloxonazine (NALZ, mu 1-opioid antagonist) and naltrindole (NTI, delta-opioid antagonist), respectively. Administration of NALZ alone, but not NTI, resulted in a slowing of the EEG. Morphine and [D-Ala2]deltorphin I (0.36 nmol/h icv) significantly increased breath number and were blocked by NALZ and NTI respectively. Both NALZ and NTI alone resulted in a reduction in breath number. These results suggest that the activation of the delta- or mu 1-opioid receptors will stimulate fetal respiratory and EEG activity. Furthermore, the endogenous opioids play a tonic role at both the delta- and mu 1-opioid receptors in the regulation of respiratory timing and EEG activity.

Animals↗
PubMed1993

DNA polymorphisms of apolipoprotein B in the population of Taiwan.

Four apolipoprotein B (apoB) genetic polymorphisms, the AluI, XbaI, MspI and EcoRI restriction fragment length polymorphisms (RFLPs), were analyzed for 162 individuals in Taiwan by polymerase chain reaction. Allele frequency determination revealed that this population has 0.86 AluI- (A-), 0.99 XbaI- (X-), 1.0 MspI+ (M+), and 0.98 EcoRI+ (E+) alleles. Major genotypes were A-/A- (0.75), X-/X- (0.98), M+/M+ (1.0) and E+/E+ (0.96). There were 0.22 A-/A+, 0.02 X-/X+ and 0.04 E+/E- heterozygous genotypes and one minor homozygous A+/A+ (0.03) genotype. The XbaI allele frequency is similar to that found in the Japanese population (XbaI- 0.96), but is significantly different from that in Caucasians (XbaI- 0.31-0.54). Significant differences (p < 0.001) between the Taiwanese and Caucasians were also observed for the AluI, EcoRI and MspI RFLP alleles of the apoB gene. More heterozygous genotypes are observed in Caucasians than in the Taiwanese.

Adult↗
PubMed1993

[The survey on arsenism caused by drinking water].

This paper reports the epidemiologic and clinical observations on arsenism caused by drinking water in Zhi Ji Liang and Tie Men Gen, Huhhot. Results showed that the content of arsenic in drinking water was eleven times as much as that of the national standard. The incidence rate of arsenism increased with the rise of arsenic content in water. In contrast to the high As content, the contents of Pb, Zn, Se were low in water and the pH value was slightly acidic. Arsenic contents in hair, fingernails and urine were all higher than those of the control. Patients with arsenism showed symptoms of anaemia.

Adolescent↗
PubMed1993

Amplification and analysis of a male-specific SRY homologous sequence of cattle.

Based on the highly conserved region of human, rabbit and mouse SRY (sex-determining region Y) sequences, primers were designed for the amplification of the unknown homologous sequence of cattle by polymerase chain reaction (PCR). A 200-bp male-specific amplifying fragment was obtained. The fragment shares high homology with the known SRY gene. By using the cloned fragment as a probe to hybridize to the Southern blot of HindIII-digested cattle genomic DNA, a 1.7-kb male-specific fragment was detected, which is considered to contain the 200-bp fragment. When the same pair of primers was used in amplification of human and goat DNA samples, the 200-bp male-specific fragment could be detected.

Animals↗
PubMed1993

Ethanol consumption by the nursing mother induces cytochrome P-4502E1 in neonatal rat liver.

Cytochrome P-4502E1 (P-4502E1) is not present in fetal rat liver because activation of the gene occurs shortly after birth. Ethanol is an inducer of P-4502E1 in adult rats. Studies were carried out to evaluate whether transplacental induction of P-4502E1 by ethanol can occur after oral consumption of ethanol by the pregnant mother. Because ethanol can be excreted in breast milk, the possible induction of P-4502E1 in neonatal liver when ethanol was consumed during the gestational and neonatal period by the mother was also determined. Pregnant rats received control or an ethanol-containing liquid diet starting on the 9th day of gestation and were killed on the 17th day or 21st day, of gestation or allowed to deliver. The rats continued on their respective diets for the first 2 weeks of the neonatal period. P-4502E1 messenger RNA (mRNA), protein or catalytic activity was not detectable in fetal liver and was not induced in the fetuses from the ethanol-consuming mothers. Transplacental induction of P-4502E1 by ethanol did not occur in this model. Induction by ethanol of P-4502E1 protein and catalytic activity but not mRNA occurred in maternal liver. P-4502E1 mRNA, protein and catalytic activity were detected shortly after birth and increased over the 2-week neonatal period. The P-4502E1 content and oxidation of p-nitrophenol or dimethylnitrosamine by hepatic microsomes from neonates of mothers consuming the ethanol diet were increased 2- to 3-fold compared with controls however, P-4502E1 mRNA levels were not elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗
PubMed1993

[Genotoxicity of herbicide 83-1 in yeast assay system].

The genotoxicity of Herbicide 83-1 (Dichloronitrophenolamide, DCNPA) was detected by the yeast D61.M and D7 assay with multi-endpoint. We noted that the frequency of cyhR (resistance to cycloheximide) colonies of D61.M treated with DCNPA on cycloheximide medium was much higher than that of the control (P < 0.01) and that there was a dose-response relationship. These showed that the positivity responsed to the mitotic crossing-over endpoint. To the remaining endpoints in the D61.M and D7 assay, however, the negative response was obtained. The results have demonstrated that Herbicide 83-1 is a DNA damage agent.

Benzamides↗
PubMed1993

Human hepatic cytochrome P450 2D6-like activity in nonhuman primates: catalytic characterization in vitro.

Previous studies have identified the monkey as an animal model for the genetic polymorphism affecting human hepatic cytochrome P450 2D6 enzyme. However, contrary to an earlier in vivo observation, the present study failed to find evidence of polymorphism of this enzyme activity in liver preparations of 84 African green (Cercopithecus aethiops) monkeys. The kinetics of dextromethorphan O-demethylation were similar in liver microsomes from African green (n = 21) and Crab eater (Macaca fascicularis, n = 7) monkeys (Km = 1.1 +/- 0.07 and 1.7 +/- 0.27 microM; Vmax = 215 +/- 71.7 and 152 +/- 21.1 nmol/mg/h, respectively). These Km values were lower and less variable than those in liver microsomes from 10 human extensive metabolizers (5.3 +/- 2.43 microM). Furthermore, the Vmax of the reaction in human liver microsomes was significantly lower (32 +/- 15.7 nmol/mg/h; P < .001). Inhibitor constants (Ki values) determined in monkey and human liver microsomes were highly correlated (r = 0.97), but two high-affinity inhibitors of the human enzyme (quinidine and lobeline) were approximately 40-fold less potent in monkey livers than in human livers. These data show that the monkey enzyme is functionally homologous, but is not identical to human hepatic cytochrome P450 2D6. Failure to observe poor metabolizer monkeys does not preclude their potential usefulness in evaluating the role of human hepatic cytochrome P450 2D6 activity in drug addiction and neurotoxicity because of the possibility of producing poor metabolizer phenocopies by potent hepatic cytochrome P450 2D6-like enzyme inhibitors in monkeys.

Animals↗
PubMed1993

Coronary artery disease risk predicted by plasma concentrations of high-density lipoprotein cholesterol, apolipoprotein AI, apolipoprotein B, and lipoprotein(a) in a general Chinese population.

We measured lipid and lipoprotein concentrations in blood samples from control subjects and patients with coronary artery disease (CAD) in Taiwan. We found significant differences (P < 0.01) in the concentrations of high-density lipoprotein cholesterol (HDLC), apolipoprotein AI (ApoAI), apolipoprotein B (ApoB), and lipoprotein(a) [Lp(a)]. Concentrations of HDLC < 350 mg/L, ApoAI < 900 mg/L, ApoB > 800 mg/L, and Lp(a) > 200 mg/L occurred, respectively, 2.8, 5.2, 1.7, and 2.3 times more frequently in the patients than in the control group. If one considers HDLC at < 350 mg/L, ApoAI at < 900 mg/L, ApoB at > 800 mg/L, and Lp(a) at > 200 mg/L as separate risk factors for CAD, the ratio of individual patients to control subjects having 4, 3, 2, 1, or 0 risk factors was [symbol: see text] 9.4, 2.1, 0.2, 0.2, respectively. Individuals displaying three or more risk factors were found 15 times more frequently in the CAD group than in the control group. These risk factors may be used clinically for the prediction and prevention of CAD in the general population.

Adult↗
PubMed1993

Induction of liver cytochrome P4502E1 by pyrazole and 4-methylpyrazole in neonatal rats.

Cytochrome P4502E1 (P4502E1) is not present in fetal rat liver; activation of the gene occurs within hours after birth. In adult rats, chemical inducers increase P4502E1 levels largely by a post-transcriptional type of mechanism. Experiments were carried out to evaluate how soon after birth chemicals such as pyrazole or 4-methylpyrazole (MP) can induce P4502E1 and whether the mechanism for induction at these early developmental stages, during active transcription, is different from that found in adults. No P4502E1 was found in fetal liver; in liver microsomes from saline control rats, there was a progressive increase in P4502E1 levels and oxidation of dimethylnitrosamine every 2 days after birth, with maximal levels 8 to 14 days after birth. Injecting pyrazole and MP on day 0 and day 1 after birth, resulted in 2- to 4-fold increases (compared to saline control values) in P4502E1 content and oxidation of dimethylnitrosamine in liver microsomes isolated from 2-day-old pups. This extent of increase by treatment with pyrazole or MP over saline control values was similar to that found when pups were treated for 2 days with the inducers on days 2, 4, 6, 8, 12 and 19 after birth. Northern blot analysis indicated a progressive increase in P4502E1 mRNA levels, reaching a maximum at about 8 days after birth for saline-treated pups. Pyrazole or MP did not increase P4502E1 mRNA levels over values for the saline controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Activation of phospholipase C by alpha 1-adrenergic receptors is mediated by the alpha subunits of Gq family.

High efficiency transient transfection of Cos-7 cells was previously used to establish the functional coupling between G alpha q/G alpha 11 and phospholipase C beta 1 (Wu, D., Lee, C-H., Rhee, S. G., and Simon, M. I. (1992) J. Biol. Chem. 267, 1811-1817). Here the same system was used to study the functional coupling between other guanine nucleotide-binding regulatory protein (G-protein) alpha subunits and phospholipases and to study which G alpha subunits mediate the activation of phospholipase C by the alpha 1-adrenergic receptor subtypes, alpha 1 A, alpha 1 B, and alpha 1 C. We found that G alpha 14 and G alpha 16 behaved like G alpha 11 or G alpha q, i.e. they could activate endogenous phospholipases in Cos-7 cells in the presence of AIFn. The synergistic increase in inositol phosphate release in Cos-7 cells after they were cotransfected with cDNAs encoding G alpha subunits and phospholipase C beta 1 indicates that both G alpha 16 and G alpha 14 can activate phospholipase C beta 1. The activation of phospholipase C beta 1 was restricted to members of the Gq subfamily of alpha subunits. They activated phospholipase C beta 1 but not phospholipase C gamma 1, gamma 2, or phospholipase C delta 3. The cotransfection of Cos-7 cells with cDNAs encoding three different alpha 1-adrenergic receptors and G alpha q or G alpha 11 leads to an increase in norepinephrine-dependent inositol phosphate release. This indicates that G alpha q or G alpha 11 can mediate the activation of phospholipase C by all three subtypes of alpha 1-adrenergic receptors. With the same assay system, G alpha 16 and G alpha 14 appear to be differentially involved in the activation of phospholipase C by the alpha 1-adrenergic receptors. The alpha 1 B subtype receptor gave a ligand-mediated synergistic response in the cells cotransfected with either G alpha 14 or G alpha 16. However, the alpha 1 C receptor responded in cells cotransfected with G alpha 14 but not G alpha 16, and the alpha 1 A receptor showed little synergistic response in cells transfected with either G alpha 14 or G alpha 16. The ability of the alpha 1 A and alpha 1 C receptors to activate phospholipase C through G alpha q and G alpha 11 was also demonstrated in a cell-free system.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Subunits beta gamma of heterotrimeric G protein activate beta 2 isoform of phospholipase C.

The activation of heterotrimeric G proteins results in the exchange of GDP bound to the alpha-subunit for GTP and the subsequent dissociation of a complex of the beta- and gamma-subunits (G beta gamma). The alpha-subunits of different G proteins interact with a variety of effectors, but less is known about the function of the free G beta gamma complex. G beta gamma has been implicated in the activation of a cardiac potassium channel, a retinal phospholipase A2 (ref. 9) and a specific receptor kinase, and in vitro reconstitution experiments indicate that the G beta gamma complex can act with G alpha subunit to modulate the activity of different isoforms of adenylyl cyclase. Of two phospholipase activities that can be separated in extracts of HL-60 cells, purified G beta gamma is found to activate one of them. Here we report that in co-transfection assays G beta gamma subunits specifically activate the beta 2 and not the beta 1 isoform of phospholipase, which acts on phosphatidylinositol. We use transfection assays to show also that receptor-mediated release of G beta gamma from G proteins that are sensitive to pertussis toxin can result in activation of the phospholipase. This effect may be the basis of the pertussis-toxin-sensitive phospholipase C activation seen in some cell systems (reviewed in refs 13 and 14).

Adenylate Cyclase Toxin↗
PubMed1992

Metabolic effects of short-chain ceramide and glucosylceramide on sphingolipids and protein kinase C.

Recent studies have identified a potential role for glucosylceramide (GlcCer) in growth promotion and hormonal signalling. In an effort to demonstrate a growth-promoting activity of GlcCer, we prepared a GlcCer having a short-chain acid (octanoyl), in the belief that this glycolipid could be absorbed more readily and more uniformly by cultured cells. By using a mixture of two specific lecithins, dioleoylglycerophosphocholine and 1-stearoyl-2-palmitoylglycerophosphocholine, we were able to prepare dispersions containing a high molar proportion of the GlcCer and the related ceramide, octanoyl sphingosine. Unexpectedly, both sphingolipids inhibited protein and DNA synthesis in Madin-Darby canine kidney cells and produced large increases in the levels of the natural lipids, GlcCer, ceramide, free sphingosine, and an amine that may be glucosylsphingosine (GlcSph). Decreases were seen in the level of sphingomyelin and the proportion of protein kinase C in the cell membranes. The level of lactosylceramide was diminished by octanoyl GlcCer but elevated considerably by octanoyl sphingosine. Diacylglycerols were increased by the lecithins in the liposomes, but the exogenous sphingolipids had no effect. Octanoyl sphingosine labeled in the sphingoid base yielded labeled GlcCer and sphingomyelin labeled in both long-chain and very-long-chain fatty acid families, as well as the octanoyl version. The two families of ceramides, however, had relatively little radioactivity. Some of these changes are attributed to rapid hydrolysis of the added lipids with the formation, particularly from the ceramide, of sphingosine and its anabolic metabolite, GlcSph. Several observations support the idea that the octanoyl sphingosine inhibited the phosphocholinetransferase that synthesizes sphingomyelin while the octanoyl GlcCer inhibited GlcCer beta-glucosidase and GlcCer galactosyltransferase. The use of unnatural short-chain lipids in the study of cell growth and other phenomena may result in unexpected changes in related metabolites and the findings from such experiments should therefore be interpreted cautiously.

Animals↗
PubMed1992

Sodium dodecyl sulfate-capillary gel electrophoresis of proteins using non-cross-linked polyacrylamide.

Proteins with relative molecular masses of 14,000 to 205,000 were separated by sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE) using non-cross-linked linear polyacrylamide gels on both coated and uncoated fused-silica capillaries. It was determined that viscosity of the acrylamide solution was a major factor affecting column stability with linear acrylamide gels. When the viscosity of the acrylamide solution reaches 100 cP, electro-osmotically driven displacement of the gels is insignificant. Uncoated capillaries provided better resolution, stability, and reproducibility than surface coated capillaries when the concentration of linear polyacrylamide was greater than 4%. At lower gel concentrations, non-cross-linked polyacrylamide is easily displaced from the columns. A calibration plot of log molecular mass vs. mobility with non-linear polyacrylamide was linear, which indicated that resolution was equivalent to that obtained with cross-linked acrylamide. Separations with model proteins indicated that baseline resolution between protein species that vary 10% in molecular mass can be achieved.

Acrylic Resins↗
PubMed1992

A polymerase chain reaction-based method for isolation of gene-specific sequences from the interferon-alpha gene cluster.

The interferon-alpha gene is a gene family of over 20 distinct genes having 80-95% homology with one another at a nucleotide level. Because of the high homology in the gene cluster, the available interferon-alpha gene probes can hybridize to multiple bands of different size on Southern blot analysis of restricted human genomic DNA. We used the polymerase chain reaction with the primers synthesized from Alu repetitive sequence and the conserved sequences of the interferon-alpha gene cluster to generate specific probes for individual interferon-alpha genes. The amplification products were subcloned into a plasmid vector and analyzed by DNA sequencing and Southern blotting of the restricted human placental DNA. One clone, which derived from interferon-alpha 14 gene, produced a single 5.2-kb band in Southern blots of the HindIII-restricted human placental DNA. This stands in contrast to the 10 bands of different size that were detected with a cDNA for the interferon-alpha I' gene. Our results indicate that a polymerase chain reaction-based method can be used to isolate gene-specific sequences from the interferon-alpha gene cluster. Since a variety of human cancers has been found to have the complete or partial deletion of the interferon-alpha gene cluster, the gene-specific probe generated by this method may aid in determining the breakpoints in the vicinity of the gene cluster.

Animals↗
PubMed1992

Members of the Gq alpha subunit gene family activate phospholipase C beta isozymes.

The relative specificities of members of the G alpha q family of GTP-binding proteins were tested for their ability to activate different phosphoinositide-specific phospholipase C (PI-PLC) beta isozymes. Cos-7 cells were transfected with cDNA corresponding to G alpha q, G alpha 11, G alpha 14, and G alpha 16. Most of the recombinant protein was bound to the cell membrane and these membranes were washed to elute endogenous PI-PLC activity. The membrane preparation was reconstituted with purified preparations of the PI-PLC beta isozymes and guanosine 5'-O-thiotriphosphate (GTP gamma S)-stimulated enzyme activity was measured. All four proteins of the G alpha q family were found to stimulate PI-PLC beta 1, with G alpha q and G alpha 11 being most efficient. On the other hand, G alpha 16 was found to most effectively activate PI-PLC beta 2, while G alpha q, G alpha 11, and G alpha 14 showed less stimulation. Specific anti- G alpha 16 antibody blocked the stimulation of both PI-PLC beta 1 and PI-PLC beta 2 in the enriched membrane fraction. We conclude that there is specificity in the interaction of different members of the Gq family with different PI-PLC beta effectors. This specificity may be important in generating tissue- or receptor-specific responses in vivo.

Amino Acid Sequence↗
PubMed1992

Usefulness of predischarge electrophysiologic study in predicting late outcome after surgical ablation of the accessory pathway in the Wolff-Parkinson-White syndrome.

A predischarge electrophysiologic study was performed in 113 patients with the Wolff-Parkinson-White (WPW) syndrome who had undergone surgical ablation of the accessory pathway. The study was performed 5 to 20 (mean 10 +/- 3) days after surgery. There were 82 male and 31 female patients (aged 4 to 58 years, mean 36 +/- 13). Sixty-one patients (54%) had manifest, 52 (46%) had concealed and 12 (11%) had multiple accessory pathways. All but 1 patient had atrioventricular reentrant tachycardia incorporating single or multiple accessory pathways during the control electrophysiologic study. The accessory pathways were located in the left ventricular free wall in 60% of cases, right ventricular free wall in 22%, posteroseptum in 13%, and anteroseptum in 5%. The predischarge electrophysiologic study showed that the accessory pathway was capable of anterograde and retrograde conductions in 4 patients (all with manifest WPW syndrome). Four patients showed induction of supraventricular tachycardia, including 2 with atrioventricular reentrant tachycardia, and 2 with atrioventricular nodal reentrant tachycardia. Recurrence of supraventricular tachycardia was noted in 5 patients during a follow-up of 28 +/- 26 months. Of these 5 patients, 2 had inducible and 3 had no inducible supraventricular tachycardia during the predischarge electrophysiologic study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Localized mutagenesis defines regions of the Bacillus thuringiensis delta-endotoxin involved in toxicity and specificity.

Bacillus thuringiensis produces a variety of delta-endotoxins which bind to specific receptors in insect larval midguts. Following insertion into the membrane there is an alteration of ion flux culminating in osmotic lysis. Mutagenic oligonucleotides were used to define regions in one of these toxins involved in specificity and toxicity. One region is highly conserved among all toxins sequenced to date and many mutations resulted in loss of toxicity for three test Lepidoptera. The mutant toxins had lost the capacity to inhibit K(+)-dependent amino acid transport into larval midgut vesicles, but there was no effect on their ability to compete with wild type toxin for binding. The results are consistent with this amphiphilic helical region of the toxin being essential for toxicity. A second mutagenized region overlapped a portion of another potential amphiphilic helix. Mutations of only 2 residues, Ala-92 and Arg-93, resulted in loss of toxicity for two lepidopteran larvae but some activity remained for a third. The A92D mutant toxin competed with the wild type toxin for binding to vesicles prepared from midguts from the sensitive but not from the insensitive larvae. Decreased toxicity was also found when this mutation was transferred to two other related protoxin genes. A number of mutations of each of these residues was analyzed and selective loss of toxicity correlated with the absence of a positive charge. Despite being distal from the presumptive specificity domain, 1 or both of these residues must have an important role in the specific binding of toxins.

Amino Acid Sequence↗