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J R Wu

Publications and source records attributed to J R Wu.

At least 37 records · Page 2Linked to original sources
PubMed1997

Origin-specific initiation of mammalian nuclear DNA replication in a Xenopus cell-free system.

The introduction of Chinese hamster ovary (CHO) cell nuclei into Xenopus egg extracts provides the only cell-free system that can efficiently initiate replication at a specific metazoan replication origin. With intact late-G1-phase nuclei as a substrate, the pattern of initiation sites for replication at the CHO dihydrofolate reductase (DHFR) locus is indistinguishable from that observed in cultured cells. By contrast, with early-G1-phase nuclei or with late-G1-phase nuclei that have damaged nuclear envelopes, these same extracts efficiently initiate replication at apparently random sites. Thus, at a distinct point during G1 phase [origin decision point (ODP)], nuclei experience a transition that is required for specific recognition of the DHFR origin by Xenopus egg cytosol. Described here are the basic requirements to achieve origin-specific initiation, which include: 1) a cell line that can be synchronized in G1 phase, 2) a method to prepare intact nuclei, 3) a technique to map origins with a few million cells, and 4) a small colony of Xenopus laevis. Immunodepletion of specific gene products allows one to test hypotheses about the requirements for origin recognition. Here we show that depletion of the Xenopus origin recognition complex subunit XORC2 from Xenopus egg extracts has no influence on the efficiency of replication or the pattern of initiation sites with either pre-ODP or post-ODP nuclei.

Animals↗
PubMed1997

Simultaneous determination of amoxycillin and clavulanic acid in pharmaceutical products by HPLC with beta-cyclodextrin stationary phase.

A simple, rapid and accurate method for simultaneous determination of amoxycillin and clavulanic acid using HPLC with beta-cyclodextrin stationary phase was developed. It involves the use of tetraethylammonium acetate (TEAA) as an additive reagent, methanol-buffer solution (pH 4.5) (35:65; v/v) as the mobile phase, detection at 225 mm and chromatogram within 12 min. Linearity and precision of the internal standard method have been obtained. Recoveries ranged from 99.25 to 105.63% for amoxycillin in the synthetic mixture. For clavulanic acid it was from 99.50 to 101.64%. This method is convenient and reproducible for analyses of these two components in different dosage forms.

Amoxicillin↗
PubMed1997

The replication origin decision point is a mitogen-independent, 2-aminopurine-sensitive, G1-phase event that precedes restriction point control.

At a distinct point during G1 phase (the origin decision point [ODP]), Chinese hamster ovary (CHO) cell nuclei experience a transition (origin choice) that is required for specific recognition of the dihydrofolate reductase (DHFR) origin locus by Xenopus egg extracts. We have investigated the relationship between the ODP and progression of CHO cells through G1 phase. Selection of the DHFR origin at the ODP was rapidly inhibited by treatment of early G1-phase cells with the protein kinase inhibitor 2-aminopurine (2-AP). Inhibition of the ODP required administration of 2-AP at least 3 h prior to phosphorylation of the retinoblastoma tumor suppressor protein (Rb) and the restriction point (R point). Cells deprived of either serum or isoleucine from metaphase throughout early G1 phase acquired the capacity to replicate in Xenopus egg extract (replication licensing) and subsequently passed through the ODP on the same schedule as cells cultured in complete growth medium. After growth arrest at the R point with hypophosphorylated Rb protein, serum- or isoleucine-deprived cells experienced a gradual loss of replication licensing. However, recognition of the DHFR origin by Xenopus egg cytosol remained stable in growth-arrested cells until the point at which all nuclei had lost the capacity to initiate replication. These results provide evidence that the ODP requires a mitogen-independent protein kinase that is activated after replication licensing and prior to R-point control.

2-Aminopurine↗
PubMed1997

Glyceryl nonivamide: a capsaicin derivative with cardiac calcitonin gene-related peptide releasing, K+ channel opening and vasorelaxant properties.

In this study, the aorta vasorelaxant, coronary calcitonin gene-related peptide (CGRP) releasing, and atrial contractility effects of glyceryl nonivamide (GLNVA) were investigated in guinea pigs. In the isolated thoracic aorta, although GLNVA (0.01-50 microM) concentration dependently induced endothelium-independent relaxations and relaxed phenylephrine-(1.0 microM) induced contractions, it failed to relax 80 mM KCI-induced contractions. The GLNVA (1.0 microM) relaxation response in the aorta was significantly inhibited by tetraethylammonium (2.5-10 mM) or ouabain (5.0 microM) and was attenuated by increased extracellular potassium gradient (10-30 mM). Glibenclamide (0.01-10 microM) dose dependently antagonized the GLNVA relaxant effect. In the isolated perfused guinea pig heart, GLNVA (0.1-10 microM) increased CGRP-like immunoreactivity outflow from coronary circulation in a concentration-dependent manner. In the isolated right and left guinea pig atria, GLNVA (0.01-10 microM) produced concentration-dependent positive inotropic and chronotropic effects, but these effects were inhibited by pretreatments with ruthenium red (1.0 microM), capsazepine (10 microM), human calcitonin-gene-related peptide (CGRP(8-37)) (1.0 microM) and sensory neuron denervation, respectively. Based on these findings, we suggest that CGRP may be released by GLNVA from cardiovascular sensory neuron, and it then activates CGRP receptors on the coronary artery and atrium. The GLNVA-induced vasorelaxant effect in the vascular smooth muscle of the aorta is due to CGRP release associated K+ channel opening, and this effect eliminates capsaicin-derived excitability-associated K+ channel blocking activities.

Animals↗
PubMed1996

A distinct G1 step required to specify the Chinese hamster DHFR replication origin.

Nuclei isolated from Chinese hamster ovary (CHO) cells at various times during the G1 phase of the cell cycle were stimulated to enter S phase by incubation in Xenopus egg cytosol. Replication of DNA initiated within the dihydrofolate reductase (DHFR) origin locus in nuclei isolated late in G1, but at random sites in nuclei isolated early in G1. A discrete transition point occurred 3 to 4 hours after metaphase. Neither replication licensing nor nuclear assembly was sufficient for origin recognition. Thus, a distinct cell cycle-regulated event in the nucleus restricts the initiation of replication to specific sites downstream of the DHFR gene.

Animals↗
PubMed1996

Reduction in lymphocyte beta-adrenergic receptor density in infants and children with heart failure secondary to congenital heart disease.

To identify changes in catecholamine levels and beta-adrenergic receptor density in children with varying degrees of congestive heart failure, we measured plasma norepinephrine (NE), epinephrine, and beta-adrenergic receptor levels in 91 noncyanotic patients using high-performance liquid chromatography and a radioligand binding assay. Plasma NE levels in 41 patients with heart failure (694 +/- 236 pg/ml) were significantly higher than those in 50 patients without it (274 +/- 68 pg/ml, p < 0.001). In addition, beta-adrenergic receptor density was significantly lower in patients with heart failure (0.81 +/- 0.48 fmol/10(6) cells) than in those without it (2.43 +/- 1.09 fmol/10(6) cells, p < 0.001), but epinephrine levels were not significantly different between the 2 groups. The receptor reduction in heart failure correlated well with elevated plasma NE levels (r = -0.60, p < 0.001). The degree of left to right shunt flow and pulmonary systolic pressure correlated directly with plasma NE levels and inversely with beta-adrenergic receptor density. From the best compromise between sensitivity and specificity, the optimal cutoff point for heart failure was > 390 ng/ml for NE and < 1.30 fmol/10(6) cells for beta-adrenergic receptor density, respectively. A follow-up study in 15 of 30 patients with heart failure after surgery showed a significant decrease in plasma NE and an increase in beta-adrenergic receptor density. Changes in plasma NE levels and beta-adrenergic receptor density occur concurrently with clinical symptoms of heart failure and may be used as indexes for assessing the presence and severity of heart failure in infants and children.

Adolescent↗
PubMed1996

Deterioration of cutaneous microcirculatory status and its clinical correlation in tetralogy of Fallot.

The purpose of this study was to evaluate the hemodynamic deterioration in cutaneous microcirculation and its clinical correlation in patients with tetralogy of Fallot (TF). Laser Doppler flowmetry and capillary microscopy were used to assess thermoregulatory and nutritional microcirculation, respectively. A significant increase in blood flow in thermoregulatory vessels was noticed only in TF patients with hemoglobin (Hb) levels under 19 g/dl. In patients with Hb levels above 19 g/dl, the blood flow declined into the normal range. This result indicated an extreme decrease of blood flow velocity in the thermoregulatory vessels in patients with Hb concentration higher than 19 g/dl. All TF patients with Hb concentrations higher than 19 g/dl revealed Maricq's type III capillaries. Type III capillaries revealed a significant retardation of capillary blood cell velocity (CBV). There was a reciprocal relationship between CBV and hematocrit (Hct). All the responses of the cutaneous microcirculation revealed a good correlation with the clinical severity of TF. All patients with type III capillaries (with Hb concentrations higher than 19 g/dl or Hct level higher than 60%) indicated an advanced disease progression. Laser Doppler flowmetry and capillary microscopy provide a sensitive noninvasive approach for the evaluation of the hemodynamic disturbances in TF and conditions resulting from long-term hypoxia.

Adolescent↗
PubMed1996

Identification of immunodominant, group-specific and subcomplex-specific, continuous epitopes in the core regions of Japanese encephalitis virus using synthetic peptides.

Two flaviviruses, Japanese encephalitis (JE) virus and Dengue (DEN) virus which have high pathogenicity for humans, continue to pose a serious public health problem in tropical and subtropical countries of the world. In order to identify the immunodominant B-cell epitopes for diagnostic application, we have prepared a series of 15-mer synthetic peptides from JE virus core protein based on computer analysis. Four linear, immunodominant epitopes corresponding to amino acids 91-105 (P78), 1-15 (P73), 8-22 (P74), and 34-48 (P75) of JE virus core proteins were identified by employing an enzyme-linked immunosorbent assay (ELISA), using high-titered immune sera from JE-vaccinated children. P78 was found to be the most immunodominant. The sero-specificity of these peptides was tested by binding to seroconverted samples from JE and DEN-1 patients. P78 and P74 belonged to group-specific epitopes which reacted with both JE and DEN-1 patient sera. P73 and P75 belonged to subcomplex-specific epitopes which reacted only with JE but not with DEN-1 patient sera. The study suggests that these peptides corresponding to the immunodominant epitopes of JE virus core protein might have the potential to be used as peptide-based diagnostic reagents for the detection and differentiation of JE and DEN antibody responses.

Adult↗
PubMed1996

Multiple sensory and functional effects of non-phenolic aminodimethylene nonivamide: an approach to capsaicin antagonist.

1. Hexylaminodimethylene nonivamide (CAPCNC6, 0.1-10 microM) inhibited the contractility of isolated guinea pig right atria, toxically revealed positive inotropic, chronotropic and then a cardiac arrest effect at 100 microM and inhibited capsaicin (1.0 microM)-induced cardiotonic effects. 2. CAPCNC6 (0.1-10 microM)-induced aorta contractions were inhibited in the presence of flunarizine, atropine, phentolamine, Ca(2+)-free solution and pre-treatment of the animal with capsaicin. 3. CAPCNC6 (1.0-300 microM)-induced trachea contractions were inhibited in the presence of capsazepine, ruthenium red, hCGRP8-37 and pre-treatment of the animal with capsaicin.

Amides↗
PubMed1996

The interfacial region of dipalmitoylphosphatidylcholine bilayers is perturbed by fusogenic amphipaths.

Several structural methods were used to probe the influence of three fusogenic and four nonfusogenic amphipaths on large, unilamellar dipalmitoylphosphatidylcholine (DPPC) vesicles. For four of these structural measurements there was a correlation observed between the ability of an amphipath to favor poly(ethylene glycol) (PEG)-induced fusion and the structural perturbation reported by each method. First, the fluorescence anisotropy of 1-[4-(trimethylamino)phenyl]-6-phenyhexa-1,3,5-triene (TMA-DPH), which probes the upper region of the bilayer, decreased in the range of PEG concentrations previously found to cause fusion of membranes containing fusogenic amphipaths. For nonfusogenic amphipaths, the anisotropy increased monotonically with PEG concentration. The properties of similar probes that locate in the hydrophobic core of the bilayer showed no correlation with fusogenicity, nor did the properties of probes purported to sense the aqueous surface of the membrane. Second, the frequency of the C=O stretch increased and then decreased dramatically as fusogenic but not nonfusogenic membranes were heated through their phase transition. Third, there was a dramatic increase in the frequency of the C-O-C ester stretch at the membrane order/disorder phase transition for membranes containing fusogenic amphipaths, twice the increase observed for nonfusogenic amphipaths. The spectral characteristics of phosphate, choline, and acyl chain motions showed no such correlation with fusogenicity. Finally, calorimetric measurements showed that low levels of fusogenic amphipaths eliminated the "pretransition" (L beta-->P beta) in DPPC membranes, whereas other amphipaths shifted but did not eliminate this transition. Taken together, these results indicate that fusogenic amphipaths perturb the interface or "backbone" region of the bilayer rather than the hydrophobic core, the headgroup, or the water interface regions of DPPC bilayers.

Calorimetry↗
PubMed1996

Insights into the complex association of bovine factor Va with acidic-lipid-containing synthetic membranes.

The mechanism of binding of blood coagulation cofactor factor Va to acidic-lipid-containing membranes has been addressed. Binding isotherms were generated at room temperature using the change in fluorescence anisotropy of pyrene-labeled bovine factor Va to detect binding to sonicated membrane vesicles containing either bovine brain phosphatidylserine (PS) or 1,2-dioleoyl-3-sn-phosphatidylglycerol (DOPG) in combination with 1-palmitoyl-2-oleoyl-3-sn-phosphatidylcholine (POPC). The composition of the membranes was varied from 0 to 40 mol% for PS/POPC and from 0 to 65 mol % for DOPG/POPC membranes. Fitting the data to a classical Langmuir adsorption model yielded estimates of the dissociation constant (Kd) and the stoichiometry of binding. The values of Kd defined in this way displayed a maximum at low acidic lipid content but were nearly constant at intermediate to high fractions of acidic lipid. Fitting the binding isotherms to a two-process binding model (nonspecific adsorption in addition to binding of acidic lipids to sites on the protein) suggested a significant acidic-lipid-independent binding affinity in addition to occupancy of three protein sites that bind PS in preference to DOPG. Both analyses indicated that interaction of factor Va with an acidic-lipid-containing membrane is much more complex than those of factor Xa or prothrombin. Furthermore, a change in the conformation of bound pyrene-labeled factor Va with surface concentration of acidic lipid was implied by variation of both the saturating fluorescence anisotropy and the binding parameters with the acidic lipid content of the membrane. Finally, the results cannot support the contention that binding occurs through nonspecific adsorption to a patch or domain of acidic lipids in the membrane. Factor Va is suggested to associate with membranes by a complex process that includes both acidic-lipid-specific and acidic-lipid-independent sites and a protein structure change induced by occupancy of acidic-lipid-specific sites on the factor Va molecule.

Adsorption↗
PubMed1996

Chromosome architecture can dictate site-specific initiation of DNA replication in Xenopus egg extracts.

Xenopus egg extracts initiate DNA replication specifically at the dihydrofolate reductase (DHFR) origin locus with intact nuclei from late G1-phase CHO cells as a substrate, but at nonspecific sites when purified DNA is assembled by the extract into an embryonic nuclear structure. Here we show that late G1-phase CHO nuclei can be cycled through an in vitro Xenopus egg mitosis, resulting in the assembly of an embryonic nuclear envelope around G1-phase chromatin. Surprisingly, replication within these chimeric nuclei initiated at a novel specific site in the 5' region of the DHFR structural gene that does not function as an origin in cultured CHO cells. Preferential initiation at this unusual site required topoisomerase II-mediated chromosome condensation during mitosis. Nuclear envelope breakdown and reassembly in the absence of chromosome condensation resulted in nonspecific initiation. Introduction of condensed chromosomes from metaphase-arrested CHO cells directly into Xenopus egg extracts was sufficient to elicit assembly of chimeric nuclei and preferential initiation at this same site. These results demonstrate clearly that chromosome architecture can determine the sites of initiation of replication in Xenopus egg extracts, supporting the hypothesis that patterns of initiation in vertebrate cells are established by higher order features of chromosome structure.

Animals↗
PubMed1996

Vasomolol: an ultra short-acting and vasorelaxant vanilloid type beta 1-adrenoceptor antagonist.

The ultra-short-acting and vasorelaxant beta 1-adrenoceptor blocking activities of vasomolol, a guaiacoxypropanolamine derivative of vanillic acid ethyl ester, were studied. Vasomolol (0.5, 1.0, 3.0 mg/kg intravenously, i.v.) produced a dose-dependent bradycardia response and demonstrated particularly a hypotensive action with an ultra-short-acting property in pentobarbital-anesthetized normotensive rats. Vasomolol's steady state of beta-blockade was attained < or = 10 min after initial infusion, and a rapid recovery from blockade occurred after discontinuation of the infusion, although intravenous infusion of vasomolol (300 micrograms/kg/min) could not inhibit pressor responses induced by (-)phenylephrine (10 micrograms/kg i.v.). In isolated rat thoracic aorta, vasomolol (1-10 microM) inhibited vascular smooth muscle contractions induced by both (-)phenylephrine (10(-5) M) and high K+ (75 mM) concentration dependently. This inhibitory effect of vasomolol was more sensitive on K(+)-induced than on (-)phenylephrine-induced contractions, suggesting that the block of Ca2+ influx may involve the major mechanism of vasorelaxation. In isolated guinea pig tissues, vasomolol (0.01-10 microM) antagonized the (-)isoproterenol (ISO)-induced positive inotropic and chronotropic effects of the atria and tracheal relaxation responses in a concentration-dependent manner. The parallel shift to the right of the concentration-response curve of (-)ISO suggested that vasomolol was a beta-adrenoceptor competitive antagonist. The effect of vasomolol was more potent on atria than on tracheal tissues, indicating that it possesses beta 1-adrenoceptor selectivity. In addition, vasomolol did not show intrinsic sympathomimetic activity (ISA). Moreover, the binding characteristics of vasomolol were evaluated in [3H]dihydroalprenolol ([3H]DHA) binding to porcine ventricular membranes. Vasomolol was an ultra-short-acting and highly selective beta 1-adrenoceptor antagonist with vasorelaxant activity and is devoid of ISA.

Adrenergic beta-Antagonists↗
PubMed1996

Circulating noradrenaline and beta-adrenergic receptors in children with congestive heart failure.

This study was designed to investigate changes in plasma catecholamine concentrations and the number of beta-adrenoceptors (beta-AR) of circulating lymphocyte in 94 noncyanotic congenital heart patients. In 43 patients with congestive heart failure, beta-AR density was significantly lower (p < 0.001) and plasma noradrenergic levels were significantly higher (p < 0.001) compared with corresponding values in 51 patients without heart failure. A significant negative correlation between lymphocyte beta-AR density and plasma noradrenergic levels was observed (r = -0.61, p < 0.001). The degree of left-to-right shunt and pulmonary pressure was correlated directly with noradrenaline level and inversely with lymphocyte beta-AR density. Both plasma noradrenaline level and lymphocyte beta-AR density return to normal in children with heart failure after surgical repair. Our results support the idea that changes in noradrenaline level and lymphocyte beta-adrenoceptor density occur concurrently with the presence and severity of heart failure in children.

Adolescent↗
PubMed1996

Nasal septal cyst--a case report.

The usual complications of submucous resection of the nasal septum (SMR) are septal hematoma, infection, hemorrhage, septal perforation, and nasal deformity. We present a case of nasal septal cyst which may be a rare complication of SMR. Entrapment of free nasal mucosal remnants or inward folding of incised septal mucosa is thought to be the cause. The patient underwent deroofment of the left cystic wall by lateral rhinotomy. There was no recurrence after one year.

Adult↗
PubMed1996

Familial supravalvular aortic stenosis: a report of two brothers.

We studied two brothers in a family with isolated congenital supravalvular aortic stenosis without Williams syndrome. Clinical, echocardiographic, hemodynamic and angiographic features of our cases were described. A severe long, narrowed supravalvular aortic stenosis involving the ascending aorta with proximal narrowing of the aortic branches and mild aortic insufficiency were found. To the best of our knowledge, this is the first report of this combination of lesions in the Orient.

Aortic Valve Stenosis↗
PubMed1996

[Clinical manifestations and effects of IVGG in patients with Kawasaki disease].

From Jan 1984 till Dec 1992, 293 patients--180 males and 113 females (M:F = 1.5:1)--with Kawasaki disease visited the Pediatric Department of Kaohsiung Medical College Hospital. The mean age from the total cases were 28.5 months (2 months-10 years). Fever was the most common clinical symptom, followed by dry cracked lips (93.5%), pharyngeal injection (92.8%) and conjunctivitis (90.5%). Only 62.6% of the total cases had cervical lymph node swelling of which the prevalence was higher than the previous report of the National Taiwan University Hospital in 1985. Two hundred and ninety-three cases were divided randomly into 3 groups according to the different treatment regimens. The first group of 199 cases whose coronary artery change occurred in 85 cases (42.7%), were treated with aspirin alone. The second group of 80 cases were treated with aspirin and IVGG 400 mg/kg/day for 5 consecutive days. The prevalence of coronary artery abnormalities was 22.5% (18/80). The third group of 14 cases were treated with aspirin and single high dose IVGG (2 gm/kg) for 10-12 hours. Coronary artery abnormalities occurred in 3 cases (21.4%). IVGG, initiated within 10 days of the onset of fever, in conjunction with aspirin decreased the prevalence of coronary artery dilatation and aneurysms significantly in comparison with treatment by the aspirin alone (p < 0.05). However, there was no difference in the prevalence of coronary aneurysm between the groups of single high dose and multiple doses, though the single high dose of IVGG can improve the clinical symptoms quickly and shorten the duration of hospitalization.

Aspirin↗