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H Wu

Publications and source records attributed to H Wu.

At least 541 records · Page 30Linked to original sources
PubMed1997

D1 dopamine receptor activity of anti-parkinsonian drugs.

Clinical and preclinical investigations suggest that stimulation of D1 dopamine receptors may be responsible for dyskinesias induced by dopamine agonist treatment of Parkinson's Disease (PD), and that these dyskinesias may be decreased by treatment with a D1 antagonist (clozapine). Therefore, the effects of dopamine agonists and antagonists have been investigated in a primary cerebellar granule cell model of cAMP formation that seems to be highly responsive to the D1 receptors. SKF 38393, lisuride, apomorphine, pergolide, dopamine, bromocriptine and 7-OH-DPAT showed concentration-dependent increases in cAMP formation, with EC50s (in microM) of 0.013, 0.053, 0.25, 1.04, 2.18, 50.9 and 54.4, respectively. SKF 38393, apomorphine, dopamine and pergolide had similar intrinsic activity (100%), while the intrinsic activities of 7-OH-DPAT, bromocriptine and lisuride were 28.0%, 20.7% and 17.2%, respectively. SCH 23390, a selective D1 dopamine receptor antagonist, blocked an increase in cAMP formation produced by EC50 concentrations of all of the dopamine agonists investigated in this study. Clozapine concentration-dependently blocked pergolide-induced increases in cAMP and was approximately 1700-fold less potent than SCH 23390 (IC50: 0.97 microM and 0.56 nM, respectively). U-95666A (1-1000 microM), selective for the D2 receptors, showed no significant effect on cAMP, while pramipexole (0.1-100 microM), a D3 preferring agonist, did not elevate cAMP. These data suggest that primary cerebellar granule cell cultures are an excellent model for measuring D1 dopamine receptor-mediated changes in cellular cAMP. The results are discussed with reference to the relationship between the D1 receptor-stimulated increase in cAMP formation and the induction of dyskinesia in humans by these anti-parkinsonian drugs.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1997

The novel anxiolytic U-101017: in vitro and ex vivo binding profile and effect on cerebellar cGMP.

The binding affinities (Ki) of U-101017 and diazepam for the GABA(A) receptor in rat cortical membranes were determined using [3H]flunitrazepam ([3H]FNZ) as the ligand. The inhibition constants of U-101017 and diazepam were 3.78 nM and 6.36 nM, respectively. Brain uptake of U-101017 was studied by the ex vivo [3H]FNZ binding assay. A significant ex vivo inhibition of [3H]FNZ binding was observed 10 min after oral administration of U-101017, and the effect lasted for at least 240 min (the last time point of investigation). The potential anxiolytic activity of U-101017 and diazepam was investigated in nonstressed and stressed (electric foot shock) mice by quantitative estimation of cerebellar cyclic 3',5'-guanosine monophosphate (cGMP). Both U-101017 and diazepam dose-dependently decreased cGMP and attenuated stress-induced elevations in cGMP. These effects were antagonized by the GABA(A) receptor antagonist flumazenil. U-101017 was about two orders of magnitude more potent in stressed animals than in controls. The results of our investigation indicate that the anxiolytic-like activity of U-101017 is mediated via GABA(A) receptors.

Animals↗
PubMed1997

U-95666E: a potential anti-parkinsonian drug with anxiolytic activity.

1. U-95666E, a D2 selective dopamine agonist, was investigated for its effect on rat striatal acetylcholine (ACh) concentration and the results were compared with those obtained with pergolide, pramipexole and bromocriptine under similar conditions. 2. U-95666E, pergolide, pramipexole and bromocriptine dose-dependently increased striatal ACh concentration both in the non-reserpinized and reserpinized rats. 3. Intrinsic activity of U-95666E was similar to pergolide and pramipexole in non-reserpinized rats, but significantly lower in reserpinized rats. 4. The sensitivity of these dopamine agonists for increasing ACh levels in the denervated as compared to innervated striatum were significantly (p < 0.01) higher. 5. U-95666E also has anxiolytic activity in mice. 6. In conclusion, U-95666E may have potential for the treatment of Parkinson's Disease and associated anxiety.

Acetylcholine↗
PubMed1997

The evolution of Msx gene function: expression and regulation of a sea urchin Msx class homeobox gene.

Msx- class homeobox genes, characterized by a distinct and highly conserved homeodomain, have been identified in a wide variety of metazoans from vertebrates to coelenterates. Although there is evidence that they participate in inductive tissue interactions that underlie vertebrate organogenesis, including those that pattern the neural crest, there is little information about their function in simple deuterostomes. Both to learn more about the ancient function of Msx genes, and to shed light on the evolution of developmental mechanisms within the lineage that gave rise to vertebrates, we have isolated and characterized Msx genes from ascidians and echinoderms. Here we describe the sequence and expression of a sea urchin (Strongylocentrotus purpouratus) Msx gene whose homeodomain is very similar to that of vertebrate Msx2. This gene, designated SpMsx, is first expressed in blastula stage embryos, apparently in a non-localized manner. Subsequently, during the early phases of gastrulation, SpMsx transcripts are expressed intensely in the invaginating archenteron and secondary mesenchyme, and at reduced levels in the ectoderm. In the latter part of gastrulation, SpMsx transcripts are concentrated in the oral ectoderm and gut, and continue to be expressed at those sites through the remainder of embryonic development. That vertebrate Msx genes are regulated by inductive tissue interactions and growth factors suggested to us that the restriction of SpMsx gene expression to the oral ectoderm and derivatives of the vegetal plate might similarly be regulated by the series of signaling events that pattern these embryonic territories. As a first test of this hypothesis, we examined the influence of exogastrulation and cell-dissociation on SpMsx gene expression. In experimentally-induced exogastrulae, SpMsx transcripts were distributed normally in the oral ectoderm, evaginated gut, and secondary mesenchyme. However, when embryos were dissociated into their component cells, SpMsx transcripts failed to accumulate. These data show that the localization of SpMsx transcripts in gastrulae does not depend on interactions between germ layers, yet the activation and maintenance of SpMsx expression does require cell-cell or cell-matrix interactions.

Animals↗
PubMed1997

Miz1, a novel zinc finger transcription factor that interacts with Msx2 and enhances its affinity for DNA.

Msx2 is a homeobox gene with a regulatory role in inductive tissue interactions, including those that pattern the skull. We demonstrated previously that individuals affected with an autosomal dominant disorder of skull morphogenesis (craniosynostosis, Boston type) bear a mutated form of Msx2 in which a histidine is substituted for a highly conserved proline in position 7 of the N-terminal arm of the homeodomain (p148h). The mutation behaves as a dominant positive in transgenic mice. The location of the mutation in the N-terminal arm of the homeodomain, a region which in other homeodomain proteins plays a key part in protein-protein interactions, prompted us to undertake a yeast two hybrid screen for Msx2-interacting proteins. Here we present a functional analysis of one such protein, designated Miz1 (Msx-interacting-zinc finger). Miz1 is a zinc finger-containing protein whose amino acid sequence closely resembles that of the yeast protein, Nfi-1. Together these proteins define a new, highly conserved protein family. Analysis of Miz1 expression by Northern blot and in situ hybridization revealed a spatiotemporal pattern that overlaps that of Msx2. Further, Miz1 is a sequence specific DNA binding protein, and it can function as a positive-acting transcription factor. Miz1 interacts directly with Msx2 in vitro and enhances the DNA binding affinity of Msx2 for a functionally important element in the rat osteocalcin promoter. The p148h mutation in Msx2 augments the Miz1 effect on Msx2 DNA binding, suggesting a reason why this mutation behaves in vivo as a dominant positive, and providing a potential explanation of the craniosynostosis phenotype.

Amino Acid Sequence↗
PubMed1997

Qualitative magnetic resonance imaging findings in geriatric depression. Possible link between later-onset depression and Alzheimer's disease?

BACKGROUND: Several clinical and neuroimaging investigations support the notion that underlying brain changes may relate to depression in older patients, especially those with a later-age initial episode. However uncertainty still exists about diagnostic and pathogenic significance of structural brain abnormalities in aged depressives, in part because many studies lack all-elderly and age-similar normal comparison populations. METHODS: Brain morphology of elderly depressives (N = 30) and normal controls (N = 36) was compared by assessing magnetic resonance imaging (MRI) brain scans with qualitative criteria-based scales. Ratings included lateral and third ventricle enlargement, and cortical, medial temporal, and caudate atrophy. RESULTS: Significant differences between depressed and control groups were not demonstrated. Later-onset depressives had significantly more left medial temporal and left caudate atrophy than early-onset counterparts of similar age. Medial temporal atrophy significantly correlated with cognitive impairment and was not related to physical illness. Depressives with medial temporal atrophy (N = 7) were older and had later age at onset of depression than those without such changes. Cerebrovascular disease risk factors did not predict MRI abnormalities. CONCLUSIONS: Results indicate non-specificity and lack of homogeneity of qualitatively measured structural brain changes in geriatric depression, but suggest that pathology of specific, lateralized brain regions may be implicated in some later-onset patients. The relationship between medial temporal atrophy and late-onset depression raises the possibility that such patients may suffer from as-yet undeclared Alzheimer's disease. Lack of association between cerebrovascular disease risk factors and brain changes suggests other pathophysiological contributions.

Aged↗
PubMed1997

Novel saponins hainaneosides A and B isolated from Marsdenia hainanensis.

Novel saponins possessing fertility-regulating activity, hainaneosides A (1) and B (2), have been isolated from the twigs and stems of Marsdenia hainanensis, and their structures have been elucidated unambiguously as 12-nicotinoyl sarcostin-3-O-beta-D-glucopyranosyl-(1-->4)-3-O-methyl-6-deoxy-bet a-D- allopyranosyl-(1-->4)-beta-D-oleandropyranosyl-(1-->4)-beta-D- cymaropyranosyl-(1-->4)-beta-D-cymaropyranoside and 12-nicotinoyl-20-cinnamoyl sarcostin-3-O-beta-D-glucopyranosyl-(1-->4)-3-O-methyl-6-deoxy-bet a-D- allopyranosyl-(1-->4)-beta-D-oleandropyranosyl-(1-->4)-beta-D-c ymaropyranoside using NMR spectroscopic techniques and chemical transformations.

Abortifacient Agents, Nonsteroidal↗
PubMed1997

Molecular cloning, structure and expression of an elicitor-inducible chitinase gene from pine trees.

We have cloned, sequenced, and examined the expression of genes from pine trees that appear to encode extracellular class II chitinase. Nucleotide sequence analysis indicates a coding sequence composed of three exons interrupted by two introns at locations identical to those found in other chitinase genes that possess introns. One of the genes, Pschi4, potentially encodes a protein that shares 62% amino acid sequence identity through the catalytic domain with class II chitinase from tobacco. In contrast, Pschi1 contains a stop codon in the first exon and may be a pseudogene. Pschi4 genes are conserved in several species of pine, and appear to comprise a small multigene family. Treatment of pine cell suspension cultures with the general elicitor chitosan induced Pschi4 expression. The regulatory sequences associated with the Pschi4 gene were sufficient to direct chitosan-inducible expression of Pschi4 in transgenic tobacco plants, which indicates that Pschi4 is an actively expressed member of the multigene family. The observation that the Pschi4 gene from pine (a gymnosperm) was appropriately regulated by chitosan in tobacco (an angiosperm) suggests that the signaling pathways that mediate chitosan-induced transcription are highly conserved in the plant kingdom.

Amino Acid Sequence↗
PubMed1997

DNA binding and bending by a chloroplast-encoded HU-like protein overexpressed in Escherichia coli.

The Guillardia theta chloroplast hlpA gene encodes a protein resembling bacterial histone-like protein HU. This gene was cloned and overexpressed in Escherichia coli cells, and the resulting protein product, HlpA, was purified and characterized in vitro. In addition to exhibiting a general DNA-binding activity, the chloroplast HlpA protein also strongly facilitated cyclization of a short DNA fragment in the presence of T4 DNA ligase, indicating its ability to mediate very tight DNA curvatures.

Bacterial Proteins↗
PubMed1997

Centric rings, acentric rings and excess acentric fragments based on a random-walk interphase chromosome model.

Excess acentric fragments, consisting of acentric rings and acentric linear fragments, are among the most frequent kinds of chromosome-type aberrations produced by radiation. The frequency of acentric rings cannot be obtained directly by experiment but is estimated here from the ratio of acentric to centric rings, evaluated using a random-walk model for the organization of chromatin during interphase and an assumption that the probability of an exchange formation is proportional to the rate of collision between two DSB. This ratio is calculated to be 2.5 in low-LET irradiated human fibroblasts, significantly greater than the ratio if proximity effects are not considered. The calculated frequency of acentric rings is insufficient to account for all the observed excess acentric fragments. Assuming that the rest of the excess acentric fragments are due to incomplete exchanges, all possible recombinations between two DSB that result in acentric rings and acentric linear fragments have been identified. From the chromosome aberration data, the incompleteness parameter has been estimated. Intra-arm chromosome exchanges, either complete or incomplete, were estimated to account for more than 50% of the excess acentric fragments in human fibroblasts.

Chromosome Aberrations↗
PubMed1997

High-level expression of cecropin CMIV in E. coli from a fusion construct containing the human tumor necrosis factor.

Cecropin CMIV gene was fused to the 3'-terminus of the mutated tumor necrosis factor (TNFb) gene and the fusion gene was directly under the control of an inducible T7 promoter in pET-11d. This fusion gene was overexpressed in Escherichia coli with an expression level of approximate 40%-50% of total cellular proteins, and was produced mainly in the form of inclusion body. Peptide with antibacterial activity was obtained by cleaving the fusion protein with CNBr.

Escherichia coli↗
PubMed1997

Glycine68 to histidine73 has an important role in the function of human tumor necrosis factor alpha.

Mutant human tumor necrosis factor alpha(hTNF alpha) genes have been constructed by in vitro mutagenesis and expressed in Escherichia coli. A deletion involving Gly68 to His73 in hTNF alpha remarkably decreased the solubility and biological activity of hTNF alpha. From the above and results of a molecular dynamics simulation it is proposed that the region of Gly68 to His73 in hTNF alpha has an important role in the maintenance of the 3-D structure and modulation of the biological activity of hTNF alpha.

Amino Acid Sequence↗
PubMed1997

Human sperm cytosolic factor triggers Ca2+ oscillations and overcomes activation failure of mammalian oocytes.

Among the possible mechanisms of oocyte activation after sperm penetration, it appears most likely that a protein released by the spermatozoon elicits a calcium elevation in the ooplasm. To further test this idea, cytosolic factors obtained from human spermatozoa by two different methods, freezing-thawing and sonication, were injected into mouse oocytes following which intracellular calcium release was measured. Of a total of 42 mouse oocytes, a pattern of calcium oscillations was observed in nine out of 16 oocytes injected with sonicated fraction, in all of eight oocytes with the frozen-thawed fraction and in none of 18 control oocytes. Injection of the frozen-thawed fraction also produced regular calcium oscillations in all of five in-vitro matured human oocytes. To assess the putative factor's ability to support fertilization, human oocytes that were not activated by prior intracytoplasmic injection of spermatozoa (ICSI) and round spermatids were reinjected with the frozen-thawed sperm fraction. Of 23 human oocytes which remained unfertilized after ICSI, 19 became activated after injection with sperm cytosolic factor; eight showed two pronuclei, three one pronucleus and eight showed three or more pronuclei. Of 11 oocytes unfertilized after prior round spermatid injection, two developed two pronuclei, four developed one pronucleus and two had three or more pronuclei. Cytogenetic analysis by fluorescence in-situ hybridization confirmed the existence of a male pronucleus in eight out of nine such zygotes displaying two or more pronuclei. Thus, human sperm extracts activated mouse and human oocytes after injection, as judged by calcium flux patterns in conjunction with male pronucleus formation.

Animals↗
PubMed1997

Progressive defect in biliary GSH secretion in streptozotocin-induced diabetic rats.

This study examined the effect of streptozotocin-induced diabetes on biliary reduced glutathione (GSH) efflux. Biliary GSH efflux was measured before and after acivicin, an irreversible inhibitor of gamma-glutamyl transpeptidase (GGT). One week after streptozotocin treatment, liver GGT activity doubled in diabetic rats but was inhibited by approximately 90% after acivicin to levels comparable to controls. Despite maximal GGT inhibition, biliary GSH efflux in untreated diabetic rats decreased progressively to approximately 10% of control levels by week 4 and was partially restored by insulin. The mechanism for the decrease in biliary GSH efflux was not increased paracellular permeability. GSH transport kinetics, ATP-stimulated taurocholate, and oxidized glutathione (GSSG) transport in canalicular liver plasma membrane prepared from diabetic and control rats were similar. Inhibition of protein kinase C (PKC) with high-dose H-7 increased biliary GSH efflux in diabetic animals to near control basal levels. In conclusion, streptozotocin-induced diabetic rats exhibit a progressive impairment in biliary GSH transport. One of the responsible mechanisms is heightened PKC tone in diabetic animals.

Animals↗
PubMed1997

[Effects of exposure to hypoxia on the skin temperature and glycogen content of frostbitten feet in rabbits].

Effect of exposure to acute hypoxia and hypoxia for 2 weeks on the skin temperature and content of glycogen of frostbitten feet in rabbits were observed. The results showed that the skin temperatures and content of glycogen were decreased in frostbite at normoxia (FN) group frostbite during acute hypoxia (FAH) group and frostbite hypoxia for 2 weeks (FH-2w) group. After treatment with warm chlorhexidine immersion the skin temperature and glycogen content in treated feet of FN and FAH group were increased, as compared with untreated feet. However, there was no difference between treated and untreated feet in FH-2w group, suggesting that there may be severe disturbance of blood circulation on frostbitten feet under this condition.

Animals↗
PubMed1997

[Effect of dietary fiber on antioxidation in rats].

The antioxidative effect of cellulose, wheat bran and pectin was studied in rats. Wistar rats (40) were randomly divided into 4 groups, 3 groups were fed with the fibers at a level of 10% in weight, the 4th group consumed stock food as control. After 3 months' feeding, MDA in serum and in RBC membrane of the 3 treated groups were significantly lower than that of the control group. The RBC membrane fluidity was significantly increased. It is suggested that these three kinds of dietary fibers can reduce the level of lipid peroxidation and inhabit free radical injury to RBC membrane in rats.

Animals↗
PubMed1997

[Determination of basic drugs in blood by RP-HPLC].

A reversed-phase HPLC method for determination of phenothiazines and tricyclin antidepressants in whole blood was described. In this paper, a model 1090 HPLC with DAD and a zorbax ODS column was used. The mobile phase was methanol: water: tritely amine (75:24.7:0.3) with pH 7.5. Cyproheptadine was used as internal standard in this method. Blood samples were extracted with the solid-phase extraction method and the liquid-liquid method. This method is suitable in forensic toxicology analysis for basic drugs.

Antidepressive Agents, Tricyclic↗