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Biomedical subjects

W Hua

Publications and source records attributed to W Hua.

At least 19 recordsLinked to original sources

Social support networks and medical service use among HIV-positive injection drug users: implications to intervention.

The study used network analysis to identify forms and sources of social support associated with a medical services use among a medically underserved population living with HIV/AIDS. Participants were African American former or current injection drug users (n=295; 34% female, 45% current drug users and 17% AIDS diagnosed). Outcomes were access to the same medical provider, use of outpatient services and emergency room (ER) use with or without subsequent hospitalization. Controlling for AIDS diagnosis, insurance, current drug use and gender, access to the same medical care provider was associated with more females in one's support network and more network sources of emotional support, financial support and instrumental assistance. Adjusting for confounders, outpatient service use was associated with more female support network members and more sources of emotional support. Controlling for participants' drug use and insurance, sub-optimal emergency department use was associated with greater number of active drug users in one's support network. Contrary to other study findings, having a supportive sex partner was associated with lower access to medical care, and kin support was not associated with medical service use. Results indicate that specific sources and forms of social support had differential influences on the sample's utilization of medical services. The findings suggest that promoting HIV-positive African American injection drug users' support network functioning may help improve HIV medical services utilization among this medically underserved population.

Adult↗

Individual and environmental factors related to quitting heroin injection.

This study examines the relationship between individual-level and the certain neighborhood characteristics with drug use cessation among a sample of long-term inner-city heroin injectors in Baltimore, Maryland. The data were derived from baseline and first follow-up visits of SHIELD, a larger HIV prevention intervention study targeting members of the drug-using community. The survey instrument was interviewer-administered and ascertained sociodemographics, drug use history, and sexual and drug risk behaviors. The data were collected between August 1997 and March 1999. The current study was limited to participants with a median age of 41 years old. 27.5% (n=53) reported quitting drug use at follow-up. Compared with those who quit, participants who continued (n=147) were close to five times as likely to buy drugs in the neighborhoods in which they lived, 80% less likely to have used drugs in a shooting gallery in the past 6 months, and close to five times more likely to have used drugs in outside places. Controlling for other factors, enrollment in drug user treatment programs or attending self-help groups were not significantly associated with drug use cessation. This study points to the importance of examining specific environmental factors in relation to quitting drug use. Research is needed to further articulate the types and characteristics of physical environments that are related to and could be intervened in promoting sustainable drug cessation.

Adult↗

The relationship between social network characteristics and exchanging sex for drugs or money among drug users in Baltimore, MD, USA.

The current study examined social network and drug use factors associated with buying and selling sex among a sample of opiate and cocaine users in Baltimore, Maryland. A sample of 702 drug users who were sexually active were administered a social network and risk behaviour inventory. Compared to 25% of men, only 1.7% of women reported a history of giving money or drugs to get sex during the past 90 days. Conversely, more women (21.2%) than men (4.7%) sold sex for money or drugs. Those who sold sex were more likely to be low frequency crack smokers, were more likely to drink alcohol at least once a day, had a higher average number of crack-only smokers in their network, and had a smaller number of kin in their network. Men who exchanged money or drugs for sex tended to be low frequency crack smokers and reported having more crack-only smokers and injectors and fewer kin in their networks. The results suggest that network composition may be a risk factor for exchanging sex, particularly with respect to crack users, while kin may be a protective factor. These associations may be either a cause or consequence of exchanging sex.

Adult↗

Evaluation of the Hexaplex assay for detection of respiratory viruses in children.

The Hexaplex assay (Prodesse, Inc., Milwaukee, Wis.) is a multiplex reverse transcriptase (RT)-PCR assay for the detection of parainfluenza virus types 1, 2, and 3, respiratory syncytial virus (RSV) types A and B, and influenza virus types A and B. We evaluated the Hexaplex assay in comparison with conventional viral cell cultures and rapid enzyme immunoassays (EIAs) for RSV (Directigen; Becton Dickinson Inc., Cockeysville, Md.) and influenza A virus (Abbott Test Pack; Abbott Laboratories, Abbott Park, Ill.) for the detection of respiratory viruses from pediatric respiratory specimens obtained from children seen at Children's Hospital of Wisconsin from December 1997 through May 1998. A total of 363 respiratory specimens were evaluated. The tissue culture prevalence of parainfluenza virus during this period of time was low (1.1%). The sensitivity, specificity, and positive and negative predictive value of Hexaplex compared to tissue culture for the detection of parainfluenza virus were 100, 95.8, 19.0, and 100%, respectively. Only one specimen was determined to contain influenza B virus by Hexaplex; it was tissue culture negative. A specimen was considered to contain RSV or influenza A virus when it was either culture positive or culture negative but Hexaplex and EIA positive. Prior to the analysis of discrepant results, the sensitivity, specificity, and positive and negative predictive value for the detection of RSV were 91.2, 100, 100, and 98.0%, respectively, for tissue culture; 84.5, 100, 100, and 96.6% for EIA; and 98.5, 91.5, 72.8, and 99.6% for Hexaplex, respectively. The sensitivity, specificity, and positive and negative predictive value for the detection of influenza A virus prior to the analysis of discrepant results were 100, 100, 100, and 100%, respectively, for culture, 78.0, 100, 100, and 89.4% for EIA, respectively, and 95.1, 94.1, 67.2, and 99.3% for Hexaplex, respectively. Culture- and/or EIA-negative, Hexaplex-positive specimens were analyzed by a second RT-PCR assay which used primers specific for a different genomic region than that used in the Hexaplex assay. After analysis of these discrepant results, the sensitivity, specificity, and positive and negative predictive value for the detection of RSV were 74.3, 100, 100, and 93.5%, respectively, for tissue culture; 70.3, 100, 100, and 92.5% for EIA; and 98.6, 97.4, 91.2, and 99.6% for Hexaplex. The sensitivity, specificity, and positive and negative predictive value for the detection of influenza A virus were 83.3, 100, 100, and 97.4%, respectively, for tissue culture; 69.4, 100, 100, and 83.3% for EIA; and 95.8, 98.7, 92.0, and 99.3% for Hexaplex. Hexaplex is a rapid, sensitive, and specific method for the detection of the seven most common respiratory viruses in children.

Child↗

Computer-aided design, synthesis and biological assay of p-methylsulfonamido phenylethylamine analogues.

Class III antiarrhythmic agents selectively delay the effective refractory period (ERP) and increase the transmembrance action potential duration (APD). Based on our previous studies, a set of 17 methylsulfonamido phenylethylamine analogues were investigated by 3D-QSAR techniques of CoMFA and CoMSIA. The 3D-QSAR models proved a good predictive ability, and could describe the steric, electrostatic and hydrophobic requirements for recognition forces of the receptor site. According to the clues provided by this 3D-QSAR analysis, we designed and synthesized a series of new analogues of methanesulfonamido phenylethylamine (VIa-i). Pharmacological assay indicated that the effective concentrations of delaying the functional refractory period (FRP) 10ms of these new compounds have a good correlation with the 3D-QSAR predicted values. It is remarkable that the maximal percent change of delaying FRP in microM of compound VIc is much higher than that of dofetilide. The results showed that the 3D-QSAR models are reliable.

Animals↗

Synthesis and characterization of pyridine-based polyamido-polyester optically active macrocycles and enantiomeric recognition for D- and L-amino acid methyl ester hydrochloride.

Five new chiral macrocycles, 3a-e, have been prepared by the acylation cyclization of chiral diamine dihydrobromide intermediates 2a-c with 2,6-pyridinedicarbonyl dichloride in highly diluted solution at room temperature. The chiral diesters 1a-c needed for the preparation of the macrocycles were obtained from condensation of corresponding N-(Z)-L-amino acids and 2,6-bishydroxymethyl pyridine in the presence of DCC and DMAP. The enantiomeric recognition of chiral macrocycles 3a-e for D- and L-amino acid methyl ester hydrochlorides has been characterized by fluorescence spectra, which indicate that some of them exhibited significant chiral recognition for the enantiomers of D- and L-amino acid methyl ester hydrochlorides. The stoichiometry and binding constants of 3a-L-Am(2) and 3c-L-Am(2) complexes have been determined. An X-ray analysis of the chiral macrocycle 3b show that the chiral ligand is rather rigid and strained.

Acylation↗

Study of infrared and mass spectra of N-2-(3'-phthalide-yl)phthalazin-1-one.

The infrared and mass spectra of N-2-(3'-phthalide-yl)phthalazin-1-one were studied. The loss of one or two natural CO residues was observed from the title compound and its partial fragment ions. Using the MIKE spectrum of ion m/z 250, its most possible structure was confirmed. Two possible paths of the formation of the title compound were also proposed.

Mass Spectrometry↗

Determination of edible bird's nest and its products by gas chromatography.

A specific gas chromatographic (GC) detection method for edible bird's nest (EBN) based on identifying the composition of the oligosaccharide chain combined with glycoprotein in EBN is developed. Five monoses (D-mannitose, D-galactose, N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, and N-acetyl neuraminate) that constitute the oligosaccharide chain are detected using GC and GC-mass spectrometry techniques; their characteristic GC spectrum can reliably be regarded as EBN's fingerprint. The peak-area ratios in GC spectrum of those five monoses are found to be fixed; therefore, the GC technique developed in this work can conveniently be used to determine various raw EBNs and their products both qualitatively and quantitatively, distinguishing between fake and genuine EBN rapidly.

Animals↗

An alternative HER-2/neu transcript of 8 kb has an extended 3'UTR and displays increased stability in SKOV-3 ovarian carcinoma cells.

UNLABELLED: HER-2/neu is a potent oncogene that predicts poor outcome when overexpressed in ovarian cancer. The SKOV-3 ovarian carcinoma cell line, one of the only models for HER2-driven ovarian cancer, expresses a major uncharacterized 8-kb alternative HER-2 transcript. OBJECTIVES: The aim of this study was to characterize the structure and determine the origin of the alternative sequence and examine the possible role of the 8-kb alternative transcript in overexpression of the HER-2 gene. METHODS: The structure of the 8-kb transcript was investigated using polymerase chain reaction (PCR) and nucleotide sequencing of cDNA clones. PCR analysis of genomic DNA was used to assess the origin of the 8-kb transcript. The stability of the 8-kb mRNA was assessed by Northern blot analysis of RNA extracted from cells treated with transcriptional inhibitors. RESULTS: Similar 5'UTR and coding sequence but an extended 3'UTR were contained in the 8-kb compared to the well-characterized 4.5-kb HER-2 transcript. Genomic DNA had continuity between the novel 3'UTR sequence from the 8-kb transcript and adjacent HER-2 terminal exon sequence. The 8-kb transcript had a half-life of 13 h compared to 5.5 h for the 4.5-kb transcript (P<0.01). CONCLUSIONS: The 8-kb transcript is generated from alternative polyadenylation site usage rather than gene rearrangement. Since the 8-kb transcript contains alternative sequence found at the 3' end of the normal HER-2 gene, it could be expressed in other cells. Increased stability of the 8-kb transcript may confer a selective advantage for SKOV-3 cells by providing enhanced HER-2 expression.

3' Untranslated Regions↗

Nimodipine inhibits calcium-independent nitric oxide synthase activity in transient focal cerebral ischemia rats and cultured mouse astroglial cells.

The effect of nimodipine on nitric oxide synthase (NOS) activities in brains in transient focal cerebral ischemia rats, in cultured mouse neurons and astroglial cells and bovine brain capillary endothelial cells (BCECs) was investigated. The administration of nimodipine (3 mg.kg(-1), p.o., twice a day, for 3 days) before middle cerebral artery (MCA) occlusion significantly reduced infarct size, decreased nitrite/nitrate (NOx) content and inhibited Ca2+-independent NOS activity in the infarct area. Nimodipine inhibited the Ca2+-independent NOS activity induced by lipopolysaccharide (LPS) + tumor necrosis factor alpha (TNF alpha) in mouse astroglial cells with an IC50 value of 0.036+/-0.003 mM and Ca2+-dependent NOS activity in mouse neurons with an IC50 value of 0.047+/-0.003 mM, but did not affect Ca2+-dependent NOS activity in BCECs. The inhibition of Ca2+-independent NOS activity by nimodipine in astroglial cells was competitive with respect to L-arginine. Nimodipine also inhibited the induction of Ca2+-independent NOS activity in vitro. These results suggest that nimodipine in addition to its cerebral vasodilating effect may protect brain from ischemic neuronal damage through modifying NOS activity.

Animals↗

Transvenous pectoral implantation of single lead implantable cardioverter defibrillator.

OBJECTIVE: To report our initial experience of transvenous pectoral implantation of single lead implantable cardioverter defibrillator (ICD) in fifteen patients. METHODS: Fifteen patients (male 13, female 2, mean age of 51.7 years), including dilated cardiomyopathy in 4, hypertrophic cardiomyopathy in 2, coronary artery disease in 5 and syncope of unknown etiology in 2, underwent ICD implantation. Indications for ICD implantation were ventricular fibrillation (8 patients) and refractory ventricular tachycardia (7 patients). All patients had syncope out of hospital. The ICD system were Medtronic Jewel active can in 5 patients (Model 7219C in 2, 7220C in 3) and CPI Ventak PRxIII in 9 patients. For active can, shocks were delivered through distal coil to ICD shell and for PRxIII through the endotak lead of proximal to distal coil. Successful implantation criteria was 2 consecutive defibrillation at less than 24 J. RESULTS: All 15 patients had successful implantation using single lead ICD system in catheter laboratory. The mean defibrillation threshold was 12.8 J (5-15 J) and R wave was 9.9 mV (3.7-14.6 mV). All devices were of pectoral implantation. No operative and perioperative complications occurred. In 7.6 months (1-18 months) of follow-up, 3 patients had VT terminated by antitachycardia pacing (ATP) and 1 patient VF terminated by shock. CONCLUSION: Transvenous pectoral implantation of single lead ICD is easy to perform and has high defibrillation efficacy and should be a preferred approach.

Defibrillators, Implantable↗

[The clinical characters of myopatic pharyngoparalysis and laryngoparalysis with 3 cases report].

OBJECTIVE: To improve the level of diagnosis and treatment about myopathic pharyngoparalysis and laryngoparalysis (MPL). METHOD: 3 cases of MPL were diagnosed by clinical inaterials, electromyogram, serokinase and muscle biopsy. The clinical characters are dysphagia, phonasthenia, abnormal electromyogram and high CPK et al. They were all treated with glucocorticoid. RESULT: The effect of treatment on all 3 cases was good. CONCLUSION: It is important to distinguish MPL with neuropathic pharyngoparalysis and laryngoparalysis. An appropriate glucocorticoid treatment is also impontant.

Adolescent↗

[Forecasting octane numbers of gasoline by NIR spectroscopy and the manufacture of octane number analyzer].

The predictive model of octane numbers, of gasoline was developed by using MLR and PLS method of chemometrics. It is applicable to forecast the MON, RON and PON of gasoline of catalytic cracking, catalytic reforming, alkylating as well as blended products. A near infrared optical multichannel analyzer (NIR-OMA) and a software package of octane number were developed. Combining both mentioned above a NIR-OM octane number analyzer was developed. With this NIR-OMONA one can obtain the MON, RON and PON (antiknock index) data in less than 1/2 minute with an accuracy of 0.6 ON unit and a precision of 0.1 ON unit by using 3-15 mL gasoline sample.

English Abstract↗

Clinical use of nonthoracotomy cardioversion-defibrillation system.

OBJECTIVE: To summarize our experience in 22 patients who had attempted nonthoracotomy implantable cardioverter-defibrillators (ICD) for malignant ventricular arrhythmias (VA). METHODS: Indications for implantation were ventricular fibrillation (VF) in 17 patients and refractory ventricular tachycardia in 5. Thirteen patients of them had underlying ischaemic heart disease. Seven had dilated cardiomyopathy and two had arrhythmogenic right ventricular dysplasia. RESULTS: 20 out of 22 patients were successfully implanted nonthoracotomic ICD with defibrillating threshold of 16.7 J. The mean hospital stay was 7.8 days. The complications included chest wall haematoma and ventricular lead dislodgment requiring repositioning. In the follow-up period of 10.1 +/- 8 months, 6 patients with VA were treated successfully by ICD. CONCLUSION: Nonthoracotomy ICD is possible in a vast majority of patients (91%) and should be considered in all patients requiring ICD without concomitant surgery.

Adolescent↗

Radiofrequency ablation of idiopathic right ventricular tachycardia.

This paper presents our experience with radiofrequency ablation (RFA) for idiopathic ventricular tachycardia (VT) arising from right ventricle in 12 patients (pts). The age range of patients was 21-50, with a mean of 38.5 years. Ten out of 12 were females, 1 patient had candia failure due to almost incessant VT while the rest had normal left ventricular function. Twelve pts had VT arising from the right ventricle; of those, 9 were from the outflow truct, 2 from the RV apex, and 1 from the RV inflow. In all pts the diagnostic study and therapeutic RFA were combined in a single procedure. Pacemapping and local activation time were used to guide the site of RFA in pts with VT arising from the right ventricle. RFA was successful in 11 of the 12 pts(91%). Number of RF applications were 1-27, mean 9.6; fluoroscopy time were 4-75, mean 26.9 minutes. RFA for idiopathic RV has a high success rate. This mode of treatment should be considered as a non-pharmacological curative treatment for symptomatic pts.

Adult↗

Coupling of kinesin steps to ATP hydrolysis.

A key goal in the study of the function of ATP-driven motor enzymes is to quantify the movement produced from consumption of one ATP molecule. Discrete displacements of the processive motor kinesin along a microtubule have been reported as 5 and/or 8 nm. However, analysis of nanometre-scale movements is hindered by superimposed brownian motion. Moreover, because kinesin is processive and turns over stochastically, some observed displacements must arise from summation of smaller movements that are too closely spaced in time to be resolved. To address both of these problems, we used light microscopy instrumentation with low positional drift (< 39 pms[-1]) to observe single molecules of a kinesin derivative moving slowly (approximately 2.5nm s[-1]) at very low (150nM) ATP concentration, so that ATP-induced displacements were widely spaced in time. This allowed increased time-averaging to suppress brownian noise (without application of external force), permitting objective measurement of the distribution of all observed displacement sizes. The distribution was analysed with a statistics-based method which explicitly takes into account the occurrence of unresolved movements, and determines both the underlying step size and the coupling of steps to ATP hydrolytic events. Our data support a fundamental enzymatic cycle for kinesin in which hydrolysis of a single ATP molecule is coupled to a step distance of the microtubule protofilament lattice spacing of 8.12 nm. Step distances other than 8nm are excluded, as is the coupling of each step to two or more consecutive ATP hydrolysis reactions with similar rates, or the coupling of two 8-nm steps to a single hydrolysis. The measured ratio of ATP consumption rate to stepping rate is invariant over a wide range of ATP concentration, suggesting that the 1 ATP to 8nm coupling inferred from behaviour at low ATP can be generalized to high ATP.

Adenosine Triphosphatases↗