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Biomedical subjects

W Wang

Publications and source records attributed to W Wang.

At least 235 records · Page 13Linked to original sources
PubMed2001

The common neurotrophin receptor p75NTR enhances the ability of PC12 cells to resist oxidative stress by a trkA-dependent mechanism.

Functional role(s) for the common neurotrophin receptor p75NTR in nerve growth factor (NGF) signaling have yet to be fully elucidated. Many studies have demonstrated that p75NTR can enhance nerve growth factor-induced survival mediated via the trkA receptor. In addition, newly identified pathways for p75NTR signaling have included distinct p75NTR-specific and trk-independent effects which generally appear to be pro-apoptotic. In the present study, we have examined the influence of p75NTR on NGF-mediated protective effects from hydrogen peroxide (H2O2)-induced apoptotic cell death of PC12 cells. Exposure of PC12 cells to H2O2 resulted in Caspase-3 activation and apoptosis. NGF protected PC12 cells against H2O2-mediated apoptosis in a dose-dependent manner and inhibited Caspase-3 activation. These effects of NGF required activation of both PI 3-kinase and MAP kinase signal pathways. When NGF binding to p75NTR was blocked by treating cells with either BDNF or PD90780, and where p75NTR expression was reduced by treating cells with antisense oligonucleotide to p75NTR, the protective effects of NGF were attenuated. Further, NGF had no effect on cell viability in PC12nn5 cells, which express only p75NTR. When trk-mediated signal transduction was blocked, leaving p75NTR signaling activated, PC12 cells were not more vulnerable to H2O2. These data suggest that p75NTR enhances the ability of PC12 cells to resist oxidative stress by a trkA-dependent mechanism, potentially by allosteric mechanisms. Further, potential trkA-independent and pro-apoptotic signaling of p75NTR does not contribute to apoptotic cell death of PC12 cells in a setting of oxidative insult.

Journal Article↗
PubMed2001

The association between HLA-A alleles and an Alu dimorphism near HLA-G.

The AluYb8 sequences are a subfamily of short interspersed Alu retroelements that have been amplified within the human genome during recent evolutionary time and are useful polymorphic markers for studies on the origin of human populations. We have identified a new member of the Yb8 subfamily, AluyHG, located between the HLA-H and -G genes and 88-kb telomeric of the highly polymorphic HLA-A gene within the alpha block of the major histocompatibility complex (MHC). The AluyHG element was characterised with a view to examining the association between AluyHG and HLA-A polymorphism and reconstructing the history of the MHC alpha block. A specific primer pair was designed for a simple PCR assay to detect the absence or presence (dimorphism) of the AluyHG element within the DNA samples prepared from a panel of 46 homozygous cell-lines containing complete or recombinant ancestral haplotypes (AH) of diverse ethnic origin and 92 Caucasoid and Asian subjects on which HLA-A typing was available. The AluyHG insertion was most strongly associated with HLA-A2 and, to a lesser degree with HLA-A1, -A3, -A11, and A-19. The gene frequency of the AluyHG insertion for 146 Caucasians and 94 Chinese-Han was 0.30 and 0.32 and there was no significant difference between the observed and expected frequencies. The results of the association studies and the phylogenetic analysis of HLA-A alleles suggest that the AluyHG sequence was integrated within the progenitor of HLA-A2, but has been transferred by recombination to other human ancestral populations. In this regard, the dimorphic AluyHG element is an important diagnostic marker for HLA association studies and could help in elucidating the evolution and functions of the MHC alpha block and polymorphism within and between ancestral haplotypes.

Alleles↗
PubMed2001

Neurosurgical trauma in People's Republic of China.

An epidemiological investigation for neurological disorders was conducted in the People's Republic of China in 1983 and 1985. The incidence of traumatic neurological injury was 55.4 patients per 100,000 population in the six big cities and 64.1 patients in the 21 rural areas. The mortality rates were 6.3 per 100,000 population (male:female = 1.7:1.0) in the six cities and 9.7 (m:f = 2.5:1) in the rural areas. In the cities, the causes of brain injury were vehicle accidents (31.7%), followed by assaults (23.8%), falls (21.8%), stumbles (15.4%), and others. Brain concussion was 68.4%, contusion was 26.0%, and intracranial hematoma was 5.6%. The incidence of spinal cord injury was 0.67 per 100,000 population in Beijing and 1.37 in Shanghai. Male versus female ratio was 7 to 1 and the peak incidence was found in ages from 20 to 30 years old. In the past decade, vehicle accidents increased along with the increasing number of cars and motor bicycles. As a result of a series of administrative measures, such as improvement of traffic control and safe-driving education, mean mortality decreased from 33.4 per 10,000 motor vehicles in 1990 to 22.0 in 1995. It has been estimated that approximately 50,000 to 60,000 people die from vehicle accidents per year. Among these cases, brain injury accounts for 39% to 57% and spinal cord injury about 10%. Since vehicle accidents are the most common cause for neurotraumatic death, an effort is needed to prevent and to decrease the incidence of these accidental traumatic injuries.

Brain Injuries↗
PubMed2001

Frequency sensitivity in Hodgkin-Huxley systems.

The frequency sensitivity of weak periodic signal detection has been studied via numerical simulations for both a single neuron and a neuronal network. The dependence of the critical amplitude of the signal upon its frequency and a resonance between the intrinsic oscillations of a neuron and the signal could account for the frequency sensitivity. In the presence of both a subthreshold periodic signal and noise, the signal-to-noise ratio (SNR) of the output of either a single neuron or a neuronal network present the typical characteristics of stochastic resonance. In particular, there exists a frequency-sensitive range of 30-100 Hz, and for signals with frequencies within this range the SNRs have large values. This implies that the system under consideration (a single neuron or a neuronal network) is more sensitive to the detection of periodic signals, and the frequency sensitivity may be of a functional significance to signal processing.

Artifacts↗
PubMed2001

Chromosome landing at the bacterial blight resistance gene Xa4 locus using a deep coverage rice BAC library.

Xa4 is a dominantly inherited rice gene that confers resistance to Philippine race 1 of the bacterial blight pathogen Xanthomonas oryzae pv. oryzae in rice. In order to isolate the gene by positional cloning, a bacterial artificial chromosome (BAC) library was constructed from genomic DNA isolated from an Xa4-harboring accession, IRBB56. The library contains 55,296 clones with an average insert size of 132 kb, providing 14 rice genome equivalents. Three DNA markers closely linked to Xa4 were used to screen the library. The marker RS13, a resistance gene analogue that co-segregates with Xa4, identified 18 clones, of which four and six, respectively, were simultaneously detected by the other two markers, G181 and L1044. Fingerprinting and Southern analysis indicated that these clones overlapped and define an interval spanning 420 kb. In an F2 population derived from an indica variety, IR24, and its Xa4-containing near isogenic line (NIL), IRBB4, the susceptible plants were screened in order to map the Xa4 gene genetically and physically. Out of 24 insert ends isolated from the BACs in the contig, three revealed polymorphisms between IR24 and IRBB4. Two insert ends, 56M22F and 26D24R, flanked Xa4 on each side. Based on the overlap of the BACs, six overlapping clones were considered to include the Xa4 allele, one of which, 106P13, was chosen for further investigation.

Blotting, Southern↗
PubMed2001

Multiple globules in a cystic ovarian teratoma.

OBJECTIVE: To describe the characteristic imaging findings of multiple globules and globules-fluid level in a cystic ovarian teratoma. DESIGN: Descriptive case study. SETTING: Mackay Memorial Hospital and National Yang-Ming University, Taipei, Taiwan, Republic of China. PATIENT(S): A 20-year-old woman with left abdominal discomfort and a palpable mass on the left side of the distended abdomen. INTERVENTION(S): Surgical removal of a 10-cm cystic ovarian teratoma that contained chocolate-like fluid and multiple spheroid mobile globules consisting of yellowish sebaceous debris and fine hair shafts. MAIN OUTCOME MEASURE(S): Plain abdominal radiography, ultrasonography, and computed tomography (CT). RESULT(S): Plain abdominal radiography revealed no calcification in the mass. The first sonographic examination showed no movement by positional change of multiple rounded echogenic masses ranging from 0.5 cm to 2 cm in diameter, but the second CT examination done after the patient had spent some time lying down showed that the rounded masses arrayed in the upper portion of the cyst and displayed the characteristic level of globules-fluid. Thus, the differential diagnosis was multiple mobile globules in a cystic ovarian tumor. CONCLUSION(S): This case indicates that fatty masses need time to float upward in the fluid matrix of a cystic ovarian teratoma. This delayed effect should be considered when an ovarian cyst with multiple rounded echogenic masses is diagnosed by ultrasonography, CT, or magnetic resonance imaging.

Abdominal Pain↗
PubMed2001

Sensation seeking correlates of passive auditory P3 to a single stimulus.

A single auditory stimulus in a passive ignore condition elicits a P3 potential (passive P3) that shares similar morphology with the classical P3 (P300 or P3b) in the active auditory 'oddball' paradigm. Since the classical P3 is correlated with introversion, anxiety, or sensation seeking, it was hypothesized that the passive P3 is correlated with sensation seeking personality. Therefore, 39 healthy subjects aged from 15 to 57 years and free from depression, were asked to answer Zuckerman's sensation seeking scales (SSS), and undergo an auditory event-related potential procedure with a single stimulus. In all subjects, a clear passive P3 appeared at three midline electrodes that shared similar latency and amplitude to the classical P3. The SSS total and experience seeking subscale scores were positively correlated with N1 amplitude at Fz. In contrast, the SSS total and some subscale scores were negatively correlated with the passive P3 amplitudes at the three electrodes. The sensation seeking personality effects on the passive P3 might be via a cortical inhibition process during memory updating, which are considered to be involved in the classical P3.

Adolescent↗
PubMed2001

Chemical constituents from Dendrobium densiflorum.

5-[2'-(3"-Hydroxy-5"-methoxyphenyl)-ethyl]-1,3-benzodioxole and 7-hydroxy-2-methoxy-1,4-phenanthrenedione, along with 16 known compounds were identified from the stems of Dendrobium densifiorum Lindl. ex Wall. (Orchidaceae). The structure of a previously reported compound dendroflorin obtained from the plant was revised on the basis of spectroscopic analysis. Among the identified compounds, five were found to exhibit anti-platelet aggregation activity in vitro.

Animals↗
PubMed2001

Chemosensitivity of serotonergic neurons in the rostral ventral medulla.

The medullary raphé contains two subtypes of chemosensitive neuron: one that is stimulated by acidosis and another that is inhibited. Both types of neuron are putative chemoreceptors, proposed to act in opposite ways to modulate respiratory output and other pH sensitive brain functions. In this review, we will discuss the cellular properties of these chemosensitive raphé neurons when studied in vitro using brain slices and primary dissociated cell culture. Quantification of chemosensitivity of raphé neurons indicates that they are highly sensitive to small changes in extracellular pH (pH(o)) between 7.2 and 7.6. Stimulation by acidosis occurs only in the specific phenotypic subset of neurons within the raphé that are serotonergic. These serotonergic neurons also have other properties consistent with a specialized role in chemoreception. Homologous serotonergic neurons are present within the ventrolateral medulla (VLM), and may have contributed to localization of respiratory chemoreception to that region. Chemosensitivity of raphé neurons increases in the postnatal period in rats, in parallel with development of respiratory chemoreception in vivo. An abnormality of serotonergic neurons of the ventral medulla has been identified in victims of sudden infant death syndrome (SIDS). The cellular properties of serotonergic raphé neurons suggest that they play a role in the CNS response to hypercapnia, and that they may contribute to interactions between the sleep/wake cycle and respiratory control.

Animals↗
PubMed2001

Mechanisms of ammonia and amino acid photoproduction from aquatic humic and colloidal matter.

Photochemical release of free amino acids was observed from dissolved fulvic acid (Suwannee River) and from colloidal fractions collected from Bayou Trepagnier, LA. Water samples were irradiated with a solar simulator, and free amino acid concentrations were determined using high performance liquid chromatography of the fluorescent derivitized amino acids. Increased concentrations of at least 20 amines were observed upon irradiation of water samples. Among the amino acids identified were alanine, asparagine, citrulline, glutamic acid, histidine, norvaline, and serine. Amino acid concentrations increased in the range of 0.03-9.5 nM h(-1). Studies on the mechanism of photochemical release of ammonia from dissolved natural organic matter (NOM) indicated at least two mechanisms. One mechanism proceeds through an hydroxyl radical intermediate. This mechanism continues in the dark after irradiation through decomposition of photochemically produced H2O2 to form hydroxyl radical. Although NOM photosensitized degradation of amino acids produces ammonia, amino acids do not appear to be an important intermediate in the photochemical formation of ammonia from NOM.

Amino Acids↗
PubMed2001

Study on the kinetics of cerium(III) adsorption-desorption on different soils of China.

The kinetics of Ce(III) adsorption-desorption on four typical soils in China has been studied by using the batch method with the radioactive nuclide 141Ce. Results indicated that Ce(III) adsorption was rapid and nearly finished in less than 0.5 min. Desorption procedure was about completed in 1-30 min in the tested soils. Ce(III) desorption equilibrium times vary with different soils. The amounts of Ce(III) desorption on different soils in the same time were different. The Elovich equation proved to be the best models for fitting the data of Ce(III) desorption reactions in fluvo-aquic soil and black soil; and the parabolic-diffusion equation was the best model in red earth and loess soil.

Adsorption↗
PubMed2001

Hypertension treatment patterns in American Indians: the strong heart study.

Pharmacologic treatment patterns for hypertensive American Indians from 13 communities in Arizona, Oklahoma, South Dakota, and North Dakota were assessed. Participants (2254 women and 1384 men, aged 48 to 79 years) completed a clinical examination between July 1993 and December 1995. The mean of two blood pressure (BP) measurements and detailed medication histories were obtained. The observed prevalence of hypertension was 46.7% (n=1698). In participants taking antihypertensive medications (n=1114), four principal drug classes were evaluated: diuretics, calcium channel blocking agents, beta-blocking agents, and angiotensin-converting enzyme (ACE) inhibitors. Among treated hypertensive participants, 71.4%, 24.6%, and 4.0% received one, two, and three medications, respectively. Among single drug regimens, ACE inhibitors (n=340) were used most often (49.4%), with calcium channel blocking agents and diuretics accounting for 24.2% and 19.9%, respectively. Although multiple drug class therapies varied, the combination of a diuretic and ACE inhibitor (n=120) accounted for 47.4% of dual therapy use. Hypertension control (SBP < 140 mm Hg, DBP < 90 mm Hg) rates were highest for those on dual therapies (65.4%), followed by participants on single (53.8%) and triple (43.6%) therapies. Among monotherapies, diuretics exhibited the best overall hypertension control rate in both diabetics (63.0%) and nondiabetics (68.0%), versus 47% to 61% for other remaining agents. The frequent use of ACE inhibitors, used singly or in combination, reflects the high prevalence of diabetes among American Indians. ACE inhibitors, combined with diuretics, were particularly useful in achieving BP control in this population.

Age Factors↗
PubMed2001

Cloning and characterization of a human lysyl oxidase-like 3 gene (hLOXL3).

Using the PCR primers generated from human expressed sequence tag (EST), the cDNA of lysyl oxidase-like gene 3 (LOXL3), a new member of human lysyl oxidases gene family, was cloned from the human fetal brain mRNA. The predicted amino acid sequence of the hLOXL3 gene was highly homologous to mLOR2. Bioinformatics analysis shows that hLOXL3 protein is also a member of the scavenger receptor cysteine-rich family, which contains a 25 amino acids signal peptide. The hLOXL3 gene was mapped to human 2p13 locus by BLAST search and at least 14 exons were found. Expression of the hLOXL3 gene was detected in several human tissues and especially high in spleen and testis.

Amino Acid Oxidoreductases↗
PubMed2001

Synthesis and characterization of a tetranucleotide analogue containing alternating phosphonate-amide backbone linkages.

Described herein is the synthesis and characterization of a tetranucleotide, 5'-dC-phosphonate-T-amide-T-ophosphonate-dC (III), in which the C-T and T-C steps contain a phosphonate backbone bond and T-T is a peptide nucleic acid dimer unit (neutral backbone). The 5'- and 3'-OH groups of the tetramer can be further derivatized and, thus, the compound is a potential building block for longer oligonucleotides which will contain alternating backbone modifications at designated positions. The synthesis involved first the preparation of two hybrid peptide-deoxyribose dinucleotides, CT-CO (I) and N-CT (II) (C and T are nucleobases; CO and N are carboxylic and amino terminal, respectively); each is linked through a phosphonate linkage. A condensation reaction between the two dimers, followed by deprotection, resulted in the formation of a peptide linkage to give the desired tetramer III. The reaction conditions used are mild to afford products in moderate to excellent yields. The DNA-PNA-DNA tetramer, d(CTTC), is a substrate for T4 kinase but fails to give a ligation product, even though NMR shows weak interactions between the tetramer III with its complementary sequence, d(GAAG).

Amides↗
PubMed2001

In vivo modification of Na(+),K(+)-ATPase activity in Drosophila.

We have constructed and characterized transgenic Drosophila lines with modified Na(+),K(+)-ATPase activity. Using a temperature dependent promoter from the hsp70 gene to drive expression of wild-type alpha subunit cDNA, we can conditionally rescue bang-sensitive paralysis and ouabain sensitivity of a Drosophila Na(+),K(+)-ATPase alpha subunit hypomorphic mutant, 2206. In contrast, a mutant alpha subunit (alpha(D369N)) leads to increased bang-sensitive paralysis and ouabain sensitivity. We can also generate temperature dependent phenotypes in wild-type Drosophila using the same hsp70 controlled alpha transgenes. Ouabain sensitivity was as expected, however, both bang sensitive paralysis or locomotor phenotypes became more severe regardless of the type of alpha subunit transgene. Using the Gal4-UAS system we have limited expression of alpha transgenes to cell types that normally express a particular Drosophila Na(+),K(+)-ATPase beta (Nervana) subunit isoform (Nrv1 or 2). The Nrv1-Gal4 driver results in lethality while the Nrv2-Gal4 driver shows reduced viability, locomotor function and uncontrolled wing beating. These transgenic lines will be useful for disrupting function in a broad range of cell types.

Animals↗
PubMed2001

TRAPP I implicated in the specificity of tethering in ER-to-Golgi transport.

TRAPP is a conserved protein complex required early in the secretory pathway. Here, we report two forms of TRAPP, TRAPP I and TRAPP II, that mediate different transport events. Using chemically pure TRAPP I and COPII vesicles, we have reconstituted vesicle targeting in vitro. The binding of COPII vesicles to TRAPP I is specific, blocked by GTPgammaS, and, surprisingly, does not require other tethering factors. Our findings imply that TRAPP I is the receptor on the Golgi for COPII vesicles. Once the vesicle binds to TRAPP I, the small GTP binding protein Ypt1p is activated and other tethering factors are recruited.

COP-Coated Vesicles↗
PubMed2001

PDZ-binding kinase participates in spermatogenesis.

A cDNA clone denoted SPK (spermatogenesis-related protein kinase) was isolated from human fetal brain cDNA library. The deduced protein was 99% identical to human PDZ-binding kinase (PBK), which is a mitotic kinase. Its isoform, which is about 300 bp longer at 3' end, was also isolated in this study. SPK gene was assigned to human chromosome 8p21.2 by radiation hybrid. Northern blot analysis indicated that SPK mRNA was predominantly expressed in testis. SPK mRNA was localized to the outer cell layer of seminiferous tubules by in situ hybridization, suggesting involvement of it in the process of spermatogenesis.

Amino Acid Sequence↗