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Biomedical subjects

D Wang

Publications and source records attributed to D Wang.

At least 775 records · Page 43Linked to original sources
PubMed1996

Acetyl coenzyme A carboxylase activity in neonatal rat cardiac myocytes in culture: citrate dependence and effects of hypoxia.

The presence of a 280,000 M(r) isoform of acetyl-CoA carboxylase (ACC-280) in the cardiac myocyte suggests that heart muscle is capable of malonyl-CoA synthesis. Cellular factors which regulate activity of ACC-280 are unknown. We have employed a neonatal rat cardiac myocyte culture (where the majority of ACC is present as ACC-280) to examine the effects of hypoxia and decreased cellular ATP on the activity of ACC in the cells. The myocyte culture has the following advantages over similar studies in the intact rat heart: the presence of a pure population of myocytes and the ability to measure cytosolic ACC free from contamination by mitochondrial carboxylases. ACC activity in cultured cardiac myocytes is completely dependent on the presence of citrate (A0.5=3.8 mM). Under control conditions, the cytosolic citrate concentration in situ is determined to be less than 1 mM. With 5 h of hypoxia, cytosolic ATP decreases from 9.85 +/- 0.23 to 2.83 +/- 0.25 mM and cytosolic AMP increases from undetectable levels to 40 +/- 0.4 microM. With hypoxia, a significant portion of the total ACC activity is now expressed in the absence of citrate and the amount of activity which is stimulated by 10 mM citrate is significantly less (1,268 +/- 0.106 nmol/4 x 10(5) cells) than is seen under control conditions (3.042 +/- 0.048). There are no significant changes in the total amount of cellular protein on the plates after 5 h of hypoxia. Consistent with net ACC activation in hypoxia, malonyl-CoA levels increase in the cells by 7 h of hypoxia. Decreased radioactive phosphate content of immunopurified ACC-280 after 5 h of hypoxia is consistent with net dephosphorylation of ACC-280 and increased citrate-independent activity.

Acetyl-CoA Carboxylase↗
PubMed1996

Genomic DNA sequence, expression, and chromosomal localization of the human B1 bradykinin receptor gene BDKRB1.

We have cloned and sequenced the human B1 bradykinin receptor gene (BDKRB1), which contains an uninterrupted coding exon. A putative promoter was identified by linking various lengths of the 5'-flanking region of the B1 receptor gene coding sequence to a CAT reporter and assaying for CAT activity. Deletion analysis showed that a 300-bp fragment in the promoter region is sufficient to direct the synthesis of the reporter and that an enhancer-like element is present between -1842 and -812. A genomic Southern blot using the B1 cDNA revealed that the receptor is encoded by a single-copy gene. The gene is located on chromosome 14q32.1-q32.2, in close proximity to the B2 receptor gene. Northern blot analysis identified a 1.7- to 1.8-kb mature mRNA transcript of the B1 receptor gene in the kidney and pancreas. A widespread tissue distribution of the B1 gene expression was identified by RT-PCR-Southern blot analysis using specific oligonucleotide probes.

Chloramphenicol O-Acetyltransferase↗
PubMed1996

Parallel Processing in Genome Mapping and Sequencing

Conventional genome mapping and sequencing involves the analysis and processing of individual samples and pieces of experimental data. Although these methods work, it is quite clear that more efficient and less expensive methods are needed. Our top down physical mapping experiments have focused on the parallel processing of information from multiple samples at one time. This approach has aided the construction of genomic restriction maps and allowed us to assess the degree of large-scale conservation across wide regions of the human genome. The principles of parallel processing were applied in top down experiments that ordered an overlapping cosmid library from the 14-Mb Schizosaccharomyces pombe genome. This approach produced an eight-fold increase in efficiency in clone ordering over similar efforts. Recently, we have developed an enhanced sequencing by hybridization protocol that allows DNA sequence information to be collected on a large number of samples at once. Our current research focuses on applying parallel processing principles to make genome-wide comparisons between pairs of samples for analyzing disease states.

Journal Article↗
PubMed1996

Cloning and expression of mouse 60 kDa ribonucleoprotein SS-A/Ro.

Autoantibodies to SS-A/Ro are among the most common found in sera of patients with systemic rheumatic diseases. These autoimmune diseases can affect various organ systems of the body and are variable in their manifestations and presentation. One of the autoimmune targets is the 60 kDa SS-A/Ro protein known to be associated with small cytoplasmic Y RNAs. To study systematically the expression of the protein, we have cloned the mouse full length 60 kDa SS-A/Ro cDNA using 5' RACE based on a cDNA sequence reported in the mouse genome project. The recombinant protein derived from the putative full-length construct was shown to react with human prototype anti-SS-A/Ro serum Ge in western blot and immunoprecipitation and comigrated with cellular 60 kDa SS-A/Ro protein in 3T3 cells. Cellular expression, measured by RT-PCR, was highest in mouse brain, followed by lung, muscle, kidney and heart. Lower levels were found in testis, liver and spleen. Like the human 60 kDa SS-A/Ro protein, the deduced mouse homolog has 538 amino acids. Sequence analysis showed 89.9% identity and 95.0% similarity between the mouse and human proteins.

Amino Acid Sequence↗
PubMed1996

Role of Wetlands in Reducing Phosphorus Loading to Surface Water in Eight Watersheds in the Lake Champlain Basin

A landscape-level approach was applied to eight rural watersheds to assess the role that wetlands play in reducing phosphorus loading to surface waters in the Lake Champlain Basin. Variables summarizing various characteristics of wetlands within a watershed were calculated using a geographic information system and then compared to measured phosphorus loading through multiple regression analyses. The inclusion of a variable based on the area of riparian wetlands located along low- and medium-order streams in conjunction with the area of agricultural and nonwetland forested lands explained 88% of the variance in phosphorus loading to surface waters. The best fit model coefficients (Pload=0.86Ag+0.64For-30Ripwet+160) suggest that a hectare of riparian wetland may be many times more important in reducing phosphorus than an agricultural hectare is in producing phosphorus. These results provide additional support for the concept that protection of riparian wetlands is an important management strategy for controlling stream water quality in multiuse landscapes.KEY WORDS: Wetlands; Phosphorus; Landscape; Regression model; Riparian; Vermont

Journal Article↗
PubMed1996

Pulmonary edema induced by phorbol myristate acetate is attenuated by compounds that increase intracellular cAMP.

We have investigated the effect of terbutaline, aminophylline and dibutyryl cyclic AMP (DBcAMP) on phorbol myristate acetate (PMA)-induced acute lung injury in isolated, blood-perfused rabbit lungs. Pulmonary arterial pressure and lung weight were measured for 30 min after a bolus injection of PMA (10 mu g/kg). In the group exposed to PMA alone, the mean pulmonary arterial pressure (PAP) increased from 16.33 + or - 1.28 to 77.30 + or - 6.40 mmHg (P <0.001), and lung weight increased by 70.69 + or - 10.94 g during the 30 min after PMA challenge (P<0.001). Pretreatment with terbutaline, aminophylline or DBcAMP prevented the increases in both PAP and lung weight (P <0.001). Each of the three drugs also prevented the increase in pulmonary vascular permeability induced by PMA: terbutaline, aminophylline, and DBcAMP all significantly reduced the pulmonary capillary filtration coefficient (KfC) as well as the albumin concentration in the lung lavage fluid after PMA exposure. Post-treatment with terbutaline 5 min after PMA administration also had a protective effect. The mechanisms responsible for these protectivp3 effects may all involve an increase in intracellular cAMP, since all three drugs increase cAMP in the lung (though by different mechanisms). Our data further indicate that the inhibition of tumor necrosis factor production may likewise play an important role in the protective effect exerted by these drugs.

Adrenergic beta-Agonists↗
PubMed1996

Factors accounting for different responses of pulmonary and cerebral vessels to hypoxia.

The roles of sympathicus, sensory neuropeptides (SNP), cyclooxygenase metabolites (COX-M), lipoxygenase metabolites (LOX-M), endothelium derived relaxing factor (EDRF), reactive oxygen (ROS) and potassium channels (PC) in the hypoxic pulmonary vasoconstriction (HPV) and hypoxic cerebral vasodilation (HCVD) were investigated in intact rats, rabbits and dogs. The results showed that during hypoxia, the excitation of sympathicus caused a constriction of both pulmonary and cerebral vessels, while SNP, EDRF and the opening of voltage sensitive PC caused the dilation of both of them; LOX-M mediated HPV and HCVD, COX-M might serve as their modulators; the blockade of ATP sensitive PC induced by hypoxia mediated HPV, but had no effect on HCVD; the reduction of O2-. in the lung might potentiate HPV, however, O2-. remained unchanged in brain during hypoxia. It is suggested that the alterations of LOX-M, ROS and the ATP sensitive PC are the factors accounting for the difference in the response of pulmonary and cerebral vessels to hypoxia.

Animals↗
PubMed1996

Experimental study on the early efficacy of excimer laser with adjunctive balloon angioplasty in dog's femoral artery.

The effect of domestically-manufactured excimer laser with adjunctive balloon angioplasty in achieving revascularization and reduction of residual stenosis was assessed. 20 femoral arteries with thrombosis and occlusion from 12 dogs were subject to angiography. At first excimer laser angioplasty was done followed by balloon angioplasty. The diameter and residual stenosis of revascularized vessel were measured. The result showed that 17 out of 20 vessels (85%) were revascularized. The diameter of revascularized vessel by excimer laser were 1.22 +/- 0.14 mm, while residual stenoses were 54% +/- 5%. After adjunctive balloon angioplasty the diameter and residual stenoses were 2.04 +/- 0.16 mm and 20% +/- 7% respectively (P < 0.05 and P < 0.01). Complication in form of vasoperforation occurred in 3/20 vessels (15%). It is concluded that China- manufactured excimer laser angioplasty is effective when used for revascularization. While the reduction of narrowing and residual stenoses was enhanced after adjunction of balloon angioplasty. This method can be employed in treating peripheral occlusive disease effectively and safely.

Angioplasty, Balloon, Laser-Assisted↗
PubMed1996

The observation of complement activation and polymorphonuclear neutrocytopenia during cardiopulmonary bypass.

By determining the plasma levels of C2, C4, factor B and polymorphonuclear neutrophils (PMNs) of the patients who received CPB, the path of complement activation and changes of PMNs were studied. The results suggest that complement system was activated through alternative pathway during CPB and was activated through classic pathway after CPB. The anaphylatoxin, the products of complement activation may be responsible for the polymorphonuclear neutrocytopenia.

Adolescent↗
PubMed1996

Production, characterization and application of the cellulase-free xylanase from Aspergillus niger.

The effects of carbon source on xylanase and cellulase production were studied. The extract of steam-exploded corn stover was found to be the best raw material for producing cellulase-free xylanase. The xylanolytic enzymes of Aspergillus niger An-76 were purified by chromatography, and the properties of the four purified components were analyzed. When the enzyme was used to treat the birch Kraft pulp, and followed by a subsequent CEH bleaching, a brightness of 6.8% SBD more than that of the untreated one using the same chlorine dosage, or a saving of nearly 50% of chlorine consumption with the same brightness, was realized.

Aspergillus niger↗
PubMed1996

C-Fos immunohistochemical localization of neurons in the mesencephalic locomotor region in the rat brain.

The projection from the limbic system via the subpallidal region to the mesencephalic locomotor region is implicated in limbic-motor integration. The goal of this study was to visualize neurons of the mesencephalic locomotor region which are active during locomotor activity induced by the disinhibition of the subpallidal region. The subpallidal region was disinhibited by picrotoxin, which antagonizes the effects of GABA. The unilateral injection of picrotoxin into the subpallidal region caused a significant increase in locomotor activity. Active tegmental neurons were subsequently visualized by immunocytochemical staining of c-Fos protein. There were significantly more immunostained neurons in the picrotoxin-injected animals than in the saline-treated rats. Heavily stained neuronal nuclei, prevailing on the brain side ipsilateral to the injection of picrotoxin, were localized within a narrow strip of tissue which stretched from the ventrolateral periaqueductal gray (including the dorsal raphe), the cuneiform nucleus, through the region of the dorsal tegmental bundle to the pedunculopontine nucleus. There were 3.5 times more immunostained neurons in the cuneiform/pedunculopontine region and 2.5 times more stained neurons in the periaqueductal region of the picrotoxin-injected rats, as compared to the saline group. This strip of immunostained cells represents neurons which are involved in the initiation and maintenance of locomotor activity due to subpallidal activation (predominantly pedunculopontine and cuneiform nuclei), as well as neurons possibly involved in the inhibition of locomotor activity (ventrolateral periaqueductal gray) and other feedback regulations. This study will help identify the neuronal pool involved in coupling the motivational commands with the locomotor system for execution of behaviour.

Animals↗
PubMed1996

Allopurinol: discrimination of antioxidant from enzyme inhibitory activities.

This study was designed to quantitatively discriminate the specific xanthine oxidase (XO) inhibitory from the relatively nonspecific antioxidant activities of allopurinol, both in vitro and in vivo in the rat. XO activity, determined by the spectrophotometric assay for urate generation over time, was completely inhibited in vitro by allopurinol at concentrations > or = 200 microM. Allopurinol's antioxidant activity was determined in vitro using a linolenic acid peroxidation (LAP) assay. Although the known antioxidant butylated hydroxytoluene effectively inhibited LAP (80% inhibition of malondialdehyde generation at 10(1) microM), allopurinol (10(1)-10(3) microM) did not inhibit this LAP (p < .01). Rat serum obtained after oral administration of allopurinol (100 mg/kg x 2 doses) did not suppress LAP in vitro more than did control rat serum. Following oral administration of allopurinol (2-50 mg/kg x 2 doses), dose-dependent inhibition of XO activity was observed in the homogenates of the liver (to 5% of control level; p < .001) and the intestine (to 12% of control level; p < .001). We conclude that while 2-50 mg/kg of oral allopurinol effectively suppresses XO activity in the rat liver and intestine, antioxidant activity is not seen even in doses up to 100 mg/kg. The selective enzymatic inhibitory effect of allopurinol at these doses therefore should provide a useful tool to allow the discrimination of the effects of xanthine oxidase in particular from the effects of reactive oxygen metabolites in general.

Allopurinol↗
PubMed1996

Seed transmission of plant viruses: a lesson in biological complexity.

Seed transmission of plant viruses results from the three-way interplay of the genetic components of the virus, the maternal host and its progeny. The challenge is to use genetic and cell biological analyses, integrated with our knowledge of plant reproduction and embryo development, to dissect this complex and rather poorly understood process.

Genes, Plant↗
PubMed1996

Pediatric clozapine intoxication.

Clozapine is a tricyclic dibenzodiazepine derivative used as an antipsychotic in adults. Clozapine's safety in children has not been established. This report describes three unintentional clozapine ingestions in pediatric patients. These are the first reported cases of clozapine intoxication in children. All three patients demonstrated dramatic alterations in mental status and tone, and two demonstrated extrapyramidal effects. Serum clozapine levels obtained in two patients were within the average range of steady state plasma concentrations for adults. These cases show the dramatic presentations of pediatric ingestion of clozapine and the differences between adult and pediatric intoxications.

Antidepressive Agents, Tricyclic↗
PubMed1996

A clinical magnetic resonance imaging study of the traumatised spinal cord more than 20 years following injury.

One hundred and fifty three patients who had sustained a spinal cord injury more than 20 years previously were assessed neurologically and by MRI scanning of their spinal cords. The spinal cord pathologies shown were, in order of prevalence, extended atrophy, malacia, syrinx, cyst, disruption and tethering. There was no relationship between the prevalence of any type of pathology and the degree of spinal canal compromise or angulation of the spine adjacent to the level of injury. Neurological changes after initial neurological stabilisation were seen only in patients with extended atrophy, malacia or a syrinx, not in those with only a cyst or cord disruption. Tethering is always associated with other lesion(s). Longer syrinxes were more likely to have associated neurological changes than shorter ones. The most common neurological change was pain.

Adult↗
PubMed1996

Angiotensin II regulation of intracellular calcium in astroglia cultured from rat hypothalamus and brainstem.

This study examines the angiotensin II (Ang II) regulation of intracellular free calcium concentration ([Ca2+]i) in astroglia cultured from the hypothalamus and brainstem of the adult rat. Bath perfusion or rapid puffer application of angiotensin II (Ang II) (1-100 nM) increased [Ca2+]i in both polygonal and stellate astroglia when measured using fura-2 imaging fluorescence microscopy. Ang II increased [Ca2+]i in 96.1 and 95.6% of the polygonal and stellate glial cells, respectively. In normal Tyrode's solution (containing 2 mM CaCl2), the Ang II-stimulated increase in [Ca2+]i characteristically showed a biphasic response, i.e., an initial rapid transient peak followed by a sustained, steady-state plateau of free Ca2+. In both cell types, the selective Ang II type 1 receptor subtype (AT1) antagonist losartan (1 microM) inhibited the Ang II-stimulated increase in [Ca2+]i. The selective AT2 antagonist PD 123319 (1 microM) did not inhibit the Ang II-stimulated increase in [Ca2+]i in either cell type. To define the sources of Ca2+ that participate in the Ang II-stimulated increase in [Ca2+]i in astroglia, experiments were performed in a nominally Ca(2+)-free Tyrode's solution. In either cell type, this resulted in only an initial transient increase of Ca2+ and no sustained plateau of Ca2+ when challenged with Ang II. Thapsigargin (5 microM), cyclopiazonic acid (10 microM), and ryanodine (10 microM), but not caffeine (1-10 mM), inhibited the initial rise in [Ca2+]i. The plateau increase of [Ca2+]i caused by Ang II (100 nM) was reversibly inhibited by both cadmium (100 microM) and nifedipine (10 microM); in contrast, gadolinium (100 microM) had no effect on the plateau increase of [Ca2+]i. These results indicate that Ang II, in physiological concentrations, can activate AT1 receptors to stimulate both Ca2+ release from intracellular stores and Ca2+ influx from the extracellular space to increase [Ca2+]i of polygonal and stellate astroglia.

Angiotensin II↗
PubMed1996

Ocular action of an opioid peptide, DPDPE.

This study was performed to examine some ocular actions of an opioid agonist. Experiments were performed to evaluate the effects of a delta opioid agonist, DPDPE ([D-pen2, D-pen5]enkephalin (where pen = penicillamine)), on: 1) intraocular pressure (IOP) in rabbits; 2) cAMP accumulation in rabbit iris ciliary bodies (ICBs). Unilateral, topical administration of DPDPE caused bilateral depression of IOP. Intravitreal injection of DPDPE caused a greater IOP decrease than intravitreal injection of NaH2PO4 (vehicle). Topical administration of naloxone partially inhibited the effect of DPDPE on IOP in normal rabbits. In other experiments, DPDPE suppressed both basal and isoproterenol (ISO)-stimulated cAMP accumulation in ICBs. The presence of naltrindole (NTI), a delta receptor antagonist, did not prevent the suppression of cAMP levels by DPDPE. The conclusions drawn from the findings suggest that the lowering of IOP by DPDPE is mediated, in part, by actions at postjunctional (ciliary body) sites and may involve an atypical opioid receptor.

Administration, Topical↗