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Biomedical subjects

R X Wang

Publications and source records attributed to R X Wang.

At least 19 recordsLinked to original sources
PubMed2001

Longitudinal sero-reactivity to human herpesvirus 8 (KSHV) in the Swiss HIV Cohort 4.7 years before KS.

The relationship between viral infection with Kaposi sarcoma-associated herpesvirus (KSHV) and the onset of Kaposi sarcoma (KS) in AIDS patients is incompletely understood. This study investigates the use of three serological assays to predict the development of KS in HIV-positive patients. Serially collected serum samples from 36 patients with KS and matched controls in the Swiss HIV Cohort Study (SHCS) were analyzed in a case control study. Three serologic assays to detect antibodies against KSHV (nuclear and membrane antigen immunofluorescence assay, N-IFA, M-IFA and ORF 65.2 ELISA) were used to determine the predictive value of KSHV-seropositivity. Serial samples from the cases were also analyzed to determine longitudinal patterns of seroreactivity and identify cases of seroconversion. Assay sensitivity for detection of KSHV antibodies was highest for M-IFA (83%), followed by N-IFA (74%) and 65.2 ELISA (52%). At the time of initial serum sampling (median 4.7 years before KS), only the N-IFA distinguished case and control sera (61% vs. 32%) and no assay was clearly predictive of subsequent onset of clinical KS. Moreover, an unexpectedly high rate of reversions to seronegativity were observed by N-IFA (27/33) as well as by 65.2 ELISA (11/26) in the longitudinal analysis. Analysis of the ORF65.2 ELISA index indicated that these reversions before the clinical onset of KS were associated with antibody levels that frequently hovered around the level of detectability. A marked increase in ORF 65.2 antibody titer occurred in a third of the patients at the time of KS diagnosis. Only two seroconversions were documented. KSHV infection within the SHCS is likely to have preceded HIV infection. KSHV infection alone is not highly predictive of KS development in this cohort of HIV-infected homosexual men as compared with matched controls. Three KSHV serologic assays, though sensitive at the time of clinical KS are inconsistently positive before the development of AIDS-related KS.

AIDS-Related Opportunistic Infections↗
PubMed2000

Death the Fas way: regulation and pathophysiology of CD95 and its ligand.

Apoptotic cell death mediated by the members of the tumor necrosis factor receptor family is an essential process involved in the regulation of cellular homeostasis during development, differentiation, and pathophysiological conditions. Among the cell death receptors comprising the tumor necrosis factor receptor superfamily, CD95/APO-1 (Fas) is the best characterized. The specific interaction of Fas with its cognate ligand, Fas ligand (FasL), elicits the activation of a death-inducing caspase (cysteine aspartic acid proteases) cascade, occurring in a transcription-independent manner. Caspase activation executes the apoptosis process by cleaving various intracellular substrates, leading to genomic DNA fragmentation, cell membrane blebbing, and the exposure of phagocytosis signaling molecules on the cell surface. Recent studies have shown that the Fas/FasL pathway plays an important role in regulating the life and death of the immune system through activation-induced cell death. In addition, these molecules have been implicated in aging, human immunodeficiency virus infection, drug abuse, stress, and cancer development. In this review, we will focus on the mechanisms that regulate Fas and FasL expression, and how their deregulation leads to diseases.

Aging↗
PubMed2000

[Pharmacognostical identification of antelope horn(Cornu Saigae Tataricae) and its adulterants].

OBJECTIVE: To provide appropriate information and scientific basis for identifying antelope horn (Saiga tatarica) contained in traditional Chinese patent medicines, and formulate relevant quality criteria through experiments. METHOD: Conducting comparative identification of macroscopic and microscopic characteristics of antelope horn(Saige tatarica) and its adulterants (Procapra gutturosa, Pantholops hodgsoni, Ovis ammon and Capra hircus) and giving a comparative table and an indented key to the main characteristics. RESULT AND CONCLUSION: There are remarkable differences between the authentic product and adulterants in both macroscopic and microscopic characteristics.

Animals↗
PubMed1999

Gene expression from the ORF50/K8 region of Kaposi's sarcoma-associated herpesvirus.

The ORF50 gene of Kaposi's sarcoma (KS)-associated herpesvirus, or human herpesvirus 8 (KSHV), activates viral replication and is weakly homologous to the herpesvirus family of R transactivators; therefore, the transcription and translation events from this region of KSHV are key events in viral reactivation. We demonstrate that ORF50 is expressed in a bicistronic message after induction of the viral lytic cycle. ORF50 migrated as a series of polypeptides: the major ones as 119 and 101 kDa, respectively. Using 3' rapid amplification of cDNA ends, RT-PCR, and cDNA library screening, we demonstrate that the major ORF50 transcript also encodes K8. The ORF50/K8 transcript was resistant to cyclohexamide, whereas the K8 transcript was only partially resistant to cyclohexamide at early timepoints. Both transcripts showed partial resistance after 12 h of phorbol ester induction. Using a GAL4-ORF50 fusion protein expression vector, we demonstrate that the transactivation domain of ORF50 resides within a 160-amino-acid region of the carboxyl portion of the ORF. Upstream regions of both ORF50 and K8 have basal promoter activity in KSHV-infected cells. K8, which had sequence homology to Bzip proteins, did not activate either promoter. However, both promoters were activated after cotransfection of ORF50 in BCBL-1 cells.

Alternative Splicing↗
PubMed1997

A genome-based resource for molecular cardiovascular medicine: toward a compendium of cardiovascular genes.

BACKGROUND: Large-scale partial sequencing of cDNA libraries to generate expressed sequence tags (ESTs) is an effective means of discovering novel genes and characterizing transcription patterns in different tissues. To catalogue the identities and expression levels of genes in the cardiovascular system, we initiated large-scale sequencing and analysis of human cardiac cDNA libraries. METHODS AND RESULTS: Using automated DNA sequencing, we generated 43,285 ESTs from human heart cDNA libraries. An additional 41,619 ESTs were retrieved from public databases, for a total of 84,904 ESTs representing more than 26 million nucleotides of raw cDNA sequence data from 13 independent cardiovascular system-based cDNA libraries. Of these, 55% matched to known genes in the Genbank/EMBL/DDBJ databases, 33% matched only to other ESTs, and 12% did not match to any known sequences (designated cardiovascular system-based ESTs, or CVbESTs). ESTs that matched to known genes were classified according to function, allowing for detection of differences in general transcription patterns between various tissues and developmental stages of the cardiovascular system. In silico Northern analysis of known gene matches identified widely expressed cardiovascular genes as well as genes putatively exhibiting greater tissue specificity or developmental stage specificity. More detailed analysis identified 48 genes potentially overexpressed in cardiac hypertrophy, at least 10 of which were previously documented as differentially expressed. Computer-based chromosomal localizations of 1048 cardiac ESTs were performed to further assist in the search for disease-related genes. CONCLUSIONS: These data represent the most extensive compilation of cardiovascular gene expression information to date. They further demonstrate the untapped potential of genome research for investigating questions related to cardiovascular biology and represent a first-generation genome-based resource for molecular cardiovascular medicine.

Blotting, Northern↗
PubMed1997

Human hematopoietic cell express two forms of the cytokine receptor common gamma-chain (gamma c).

Recent studies have revealed that the gamma-chain of the IL-2 receptor is shared by the receptors for IL-4, IL-7, IL-9, IL-13, and IL-15, and it is therefore also referred to as the common gamma-chain (gamma c). Mutations of gamma c result in X-linked severe combined immunodeficiency syndrome in humans, indicating that gamma c is essential for normal development and function of the immune system. We demonstrate that human hematopoietic cells express two gamma c transcripts differing in their carboxyl terminal coding region. One transcript is the previously reported sequence (gamma c-long), whereas the newly identified sequence exhibits a deletion of 72 nucleotides close to the 3'-end of the open reading frame (gamma c-short). This alteration predicts a loss of 24 amino acids including a conserved tyrosine residue which is shared by several members of the cytokine receptor family. The presence of these two distinct forms of gamma c transcripts was demonstrated by sequencing of reversely transcribed and polymerase chain reaction (RT-PCR) amplified mRNA, restriction digestion of the RT-PCR products, RNAse protection, and Northern blotting from human cell lines and human peripheral blood lymphocytes. Furthermore, the two variants were present in peripheral blood lymphocytes from both female and male donors, which rules out allelic variants since gamma c is a single copy gene located on the X chromosome. A truncation mutant at a site near the observed changes in gamma c-short has been reported by others to alter biochemical events activated by cytokines. This combined with the loss of a potential SH2 "docking" site in gamma c-short suggests that gamma c-long and gamma c-short may link to different signaling pathways and may play an important role in determining the cellular response to IL-2, IL-4, IL-7, IL-9, IL-13, IL-15.

Alternative Splicing↗
PubMed1997

Distribution of mRNA encoding three alpha 2-adrenergic receptor subtypes in the developing mouse embryo suggests a role for the alpha 2A subtype in apoptosis.

alpha 2-Adrenergic receptors (alpha 2-ARs) respond to norepinephrine and epinephrine to mediate diverse physiological effects. Using in situ hybridization, the expression pattern of the mRNA encoding the three alpha 2-AR subtypes (alpha 2A, alpha 2B, and alpha 2C) was examined in the mouse embryo. The mRNA encoding the three subtypes was first detected at stage 9.5 days postcoitus (d.p.c.) for the alpha 2A-AR (coincident with norepinephrine availability), 11.5 d.p.c. for the alpha 2B-AR, and 14.5 d.p.c. for the alpha 2C-AR subtype. The mRNA encoding the alpha 2A-AR subtype shows both the earliest and the most widespread expression pattern, including developing stomach and cecum, many craniofacial regions and areas in the central nervous system. Strikingly, the alpha 2A-AR mRNA is expressed in the interdigital mesenchyme between stage 12.5 and 14.5 d.p.c. in parallel with digit separation, raising the possibility that the alpha 2A-AR might contribute to the apoptotic events underlying this process. To test whether alpha 2A-AR can signal apoptotic events, the alpha 2A-AR subtype was introduced into two mouse mesenchymal cell lines, C3H/10t1/2 and NIH-3T3; expression of the alpha 2A-AR correlated with accelerated apoptosis, as detected both by the TUNEL assay and the loss of cell viability. In contrast to the wide distribution of mRNA encoding the alpha 2A-AR subtype, the alpha 2B-AR mRNA was detected only in the developing liver and was most readily detectable between 11.5 and 14.5 d.p.c., when the liver is the principal site of hematopoiesis. The alpha 2C-AR mRNA is detected in the nasal cavity and cerebellar primordium only at > or = 14.5 d.p.c. These studies represent the first characterization of the temporal and spatial expressions of the alpha 2A-AR, alpha 2B-AR, and alpha 2C-AR subtypes during embryogenesis and provide important insights concerning the loci and possible roles of alpha 2-AR-mediated regulation of physiological processes during the developmental program.

Animals↗
PubMed1997

Construction of a human heart cDNA library and identification of cardiovascular based genes (CVBest).

The availability of high quality cDNA libraries is often crucial to the successful identification and characterization of genes. The concepts and potential pitfalls of constructing cDNA libraries are presented. Various applications requiring high quality cDNA libraries are outlined, including large-scale single pass sequencing of cDNA clones to generate expressed sequence tags (ESTs) and differential screening of cDNA libraries. The usefulness of combining such approaches for the discovery of novel disease-related and cardiovascular-based ESTs (CVBest) is discussed.

Base Sequence↗
PubMed1995

Analysis of expressed sequence tags from a fetal human heart cDNA library.

Single-pass sequencing of randomly selected cDNA clones to generate expressed sequence tags (ESTs) has been widely used to identify novel genes and to study gene expression in a variety of tissues. We have generated 2244 ESTs from a human fetal heart library (GenBank Accession Nos. R30692-30774 and R56965-58824), which we present in this report. Of these, 51.7% showed no homology to known genes or were similar only to other ESTs, while 48.4% demonstrated homology to known transcripts. A total of 764 ESTs corresponding to known genes were used to study gene expression patterns in the fetal heart and to analyze differences in these patterns from those observed in the adult heart. These analyses demonstrate the utility of ESTs and sequence-tagged clones in comparative studies of gene expression in the cardiovascular system, and they reveal that differential gene expression underlies the structural and functional characteristics of the developing heart.

Adult↗
PubMed1994

The identification of NP25: a novel protein that is differentially expressed by neuronal subpopulations.

A novel gene encoding a 25-kDa neuronal-specific protein, here named 'NP25', has been isolated as a cDNA clone from rat brain. The sequence of the NP25 cDNA reveals a single open reading frame that encodes a primary translation product of 206 amino acids. A search of the protein sequence databank indicates that NP25 is significantly homologous with three recently discovered muscle proteins: SM22 alpha, mp20 and calponin. The gene is specifically and ubiquitously expressed in the rat brain and has conserved sequences among chicken, rat, mouse and human. Rat brain NP25 was identified by Western blot using an antiserum elicited against trpE-NP25 fusion protein. On pH gradient electrophoresis, NP25 was separated into at least two isoforms with similar molecular weights. Immunocytochemistry and in situ hybridization demonstrated that NP25 was differentially expressed by neuronal subpopulations of the rat central nervous system. The highest concentration of NP25 protein was localized in central amygdaloid nuclei and glomeruli in the granule layer of cerebellum. The wide and differential distribution of NP25 in the brain suggests that it may play a particular important role in the function of specific neuronal systems.

Amino Acid Sequence↗
PubMed1994

Insulin delivery in nosedrops: new formulations containing alkylglycosides.

Insulin was administered to rats via nosedrops in the presence or absence of various alkylglycosides; systemic insulin absorption was measured as a fall in blood D-glucose concentration in animals made hyperglycemic by xylazine/ketamine anesthesia. Nosedrops (0.04 ml) containing alkylglycosides or regular porcine insulin alone were without effect. Nosedrops containing both a small amount of alkylglycoside (0.03-0.50%) and insulin (2 U regular porcine) caused a rapid decrease in blood D-glucose levels and a concomitant increase in serum immunoreactive insulin levels. The maximal hypoglycemic response was observed between 60 and 120 min after delivery of nosedrops. Decylmaltoside was less effective at enhancing systemic insulin absorption than dodecylmaltoside, tridecylmaltoside, or tetradecylmaltoside, whereas octylmaltoside was totally ineffective. Dodecylsucrose, a compound which differs from dodecylmaltoside only in one carbohydrate residue, had a similar effect on blood D-glucose values when it was included in the nosedrop formulation with insulin. Decylsucrose was considerably less potent than dodecylsucrose at enhancing systemic absorption of insulin. Nonylglucoside was effective at promoting insulin absorption from nosedrops only when used at higher doses (0.25-0.50%), whereas heptylglucoside and hexylglucoside were ineffective. These results indicated that nosedrops containing insulin plus an extremely low concentration (0.03%) of an absorption-enhancing agent such as tetradecylmaltoside can be used to lower blood D-glucose values.

Absorption↗
PubMed1994

Alkylglycosides enhance systemic absorption of insulin applied topically to the rat eye.

A series of alkylglycosides with various alkyl chain lengths and carbohydrate residues were tested for their ability to enhance systemic absorption of insulin after topical ocular delivery in anesthetized rats. Several reagents, including tetradecyl-, tridecyl- and dodecylmaltoside and dodecylsucrose, were potent stimulators of insulin absorption when used at concentrations as low as 0.125%. Other alkylglycosides such as decylsucrose, decylmaltoside, nonylglucoside, octylmaltoside, heptylglucoside and hexylglucoside were less potent or ineffective as absorption-enhancing reagents. By comparison, the bile salt sodium glycocholate was effective only when used at concentrations of 0.5% or greater. All of the reagents were effective only when used at concentrations above their critical micelle concentration and the most hydrophobic alkylglycoside reagents were the most efficacious at promoting systemic insulin absorption. The possible utilization of eyedrops containing insulin plus an absorption-enhancing alkylglycoside reagent in humans is discussed.

Absorption↗
PubMed1993

[Effects of scoparone on hemodynamics in anesthetized rabbits].

The effects of scoparone (Sco), tetramethylpyrazine (TMP), and papaverine (Pap) on hemodynamics were compared in anesthetized rabbits. Three dosage levels (1.25, 2.5, 5 mg.kg-1, iv) were used for each agent. Sco lowered the blood pressure (BP), increased the cerebral blood flow (CBF) dose-dependently, but did not show significant influence on the femoral artery blood flow (FBF), the maximal decrease of BP, and the maximal increases of CBF being 15% and 20% of the control, respectively. In contrast, TMP raised the BP as well as increased the CBF and FBF simultaneously. Pap, however, lowered the BP, slightly increased the CBF and decreased the FBF only at large doses. The results suggested that Sco may cause a selective dilatation of cerebral blood vessels.

Animals↗
PubMed1991

Isolation and characterization of a previously unrecognized myosin heavy chain gene present in the Syrian hamster.

A full length (25,000 base-pair) myosin heavy chain gene completely contained within a single cosmid clone was isolated from a Syrian hamster cosmid genomic library. Sequence comparison of the 3' untranslated region indicated the presence of a 75% homology with the rat embryonic myosin heavy chain gene. Extensive 5' flanking region regulatory element conservation was also found when the sequence was compared to the rat myosin heavy chain gene. S1 nuclease digestion analysis, however, indicated that the Syrian hamster myosin heavy chain gene exhibited expression in adult Syrian hamster ventricular tissue, as well as the adult vastus medialis, a fast twitch skeletal muscle. Expression also appears to be enhanced in myopathic relative to control hearts. This myosin heavy chain gene is neither the alpha nor beta cardiac myosin heavy chain gene, but is a unique, previously unrecognized, myosin heavy chain gene present in both myocardial and skeletal muscle tissues.

Animals↗