Biomedical subjects

Zhiwei Zhang

Publications and source records attributed to Zhiwei Zhang.

10 recordsLinked to original sources

PubMed2006

Capillary electrophoresis with electrochemiluminescence detection for measurement of aspartate aminotransferase and alanine aminotransferase activities in biofluids.

A new sensitive assay for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in biofluids was developed, based on the separation and detection of alanine, glutamate, and aspartate using capillary electrophoresis (CE) with electrochemiluminescence (ECL) detection. The three amino acids were separated in 5 mM phosphate of pH 2.1 as background electrolyte, and detected on a 500 microm platinum disk electrode at 1.2V (versus Ag/AgCl) in the presence of 10 mM tris(2,2'-bipyridyl)ruthenium(II) dissolved in 80 mM phosphate of pH 10.5. A mass detection limit of 37.3 fmol (or 81.5 fmol) for glutamate, corresponding to the product in the enzyme reaction catalyzed by 1.24 x 10(-9)U AST (or 2.72 x 10(-9)U ALT) in a 30 min reaction period, was achieved. This assay was applied to investigate the cytotoxicity effect of ethanol on HepG2 cells and differentiating nonalcoholic steatohepatitis (NASH) from alcoholic liver disease, indicating that the technique is promising for the application in the cell biological and clinical fields.

Alanine↗

PubMed2006

Do mechanisms that link addiction treatment patients to primary care influence subsequent utilization of emergency and hospital care?

BACKGROUND: Patients with drug use disorders are heavy users of emergency department (ED) and inpatient hospital care. This study examines whether formal mechanisms to link addiction treatment patients to primary medical care, either directly on site or by off-site referral-when compared with an absence of said mechanisms-might reduce these patients' use of ED and hospital services after substance abuse treatment. METHODS: We used longitudinal data from 6 methadone maintenance programs with 232 patients, 24 outpatient nonmethadone programs with 1202 patients, and 14 long-term residential programs with 679 patients in the National Treatment Improvement Evaluation Study. Multivariate logistic models controlling for health status and medical service utilization before treatment examined whether provision of medical services on- or off-site during treatment linkage led to reduced use of ED and hospital services in the year after treatment compared with no such provision. RESULTS: On-site delivery of primary care reduced subsequent ED and hospital use among patients in methadone maintenance and long-term residential compared with the nonlinkage condition but not in outpatient nonmethadone programs. Off-site referral for medical care reduced subsequent ED visits but not hospitalizations in long-term residential programs. CONCLUSIONS: These findings suggest that for some treatment modalities, stronger primary care linkage mechanisms decrease subsequent utilization of expensive ED and hospital services. Future study should examine the cost implications of these strong linkage mechanisms and ways to strengthen linkages to off-site medical care.

Adult↗

PubMed2005

A colorimetric method for point mutation detection using high-fidelity DNA ligase.

The present study reported proof-of-principle for a genotyping assay approach that can detect single nucleotide polymorphisms (SNPs) through the gold nanoparticle assembly and the ligase reaction. By incorporating the high-fidelity DNA ligase (Tth DNA ligase) into the allele-specific ligation-based gold nanoparticle assembly, this assay provided a convenient yet powerful colorimetric detection that enabled a straightforward single-base discrimination without the need of precise temperature control. Additionally, the ligase reaction can be performed at a relatively high temperature, which offers the benefit for mitigating the non-specific assembly of gold nanoparticles induced by interfering DNA strands. The assay could be implemented via three steps: a hybridization reaction that allowed two gold nanoparticle-tagged probes to hybrid with the target DNA strand, a ligase reaction that generates the ligation between perfectly matched probes while no ligation occurred between mismatched ones and a thermal treatment at a relatively high temperature that discriminate the ligation of probes. When the reaction mixture was heated to denature the formed duplex, the purple color of the perfect-match solution would not revert to red, while the mismatch gave a red color as the assembled gold nanoparticles disparted. The present approach has been demonstrated with the identification of a single-base mutation in codon 12 of a K-ras oncogene that is of significant value for colorectal cancers diagnosis, and the wild-type and mutant type were successfully scored. To our knowledge, this was the first report concerning SNP detection based on the ligase reaction and the gold nanoparticle assembly. Owing to its ease of operation and high specificity, it was expected that the proposed procedure might hold great promise in practical clinical diagnosis of gene-mutant diseases.

Cell Line↗

PubMed2004

The effect of matching comprehensive services to patients' needs on drug use improvement in addiction treatment.

AIMS: To examine whether need-service matching in addiction treatment leads to improvements in drug use, and whether treatment duration mediates those improvements. DESIGN, PARTICIPANTS, MEASUREMENTS: This analysis utilizes prospective data from a US cohort of addiction treatment patients who reported service needs beyond core rehabilitative services (n = 3103). 'Drug use improvement' is the difference between the patient's peak drug use frequency (in days per month) in the year before intake and in the year after treatment. Overall and primary use of the major illicit drugs (heroin, powder or crack cocaine and marijuana) are considered separately. 'Need-service match' means that a patient rated a service as important at intake and reported its receipt during treatment. 'Percentage of needs matched' indicates the proportion of five service domains (medical, mental health, family, vocational and housing) so matched. FINDINGS: In mixed regression models controlling for multiple factors, a greater percentage of needs matched tended to improve primary (beta = 0.028, P = 0.09) and overall (beta = 0.049, P = 0.05) drug use in the follow-up year. Exclusion of treatment duration as a covariate doubled the magnitude of these coefficients. The benefits of matching were concentrated among the half of patients reporting needs in four to five rather than one to three domains, and were strongest among patients in long-term residential facilities. Addressing vocational and housing needs exerted the greatest effects. CONCLUSIONS: Matching comprehensive services to needs is a useful addiction treatment practice, especially for high-need patients. Treatment duration might partially mediate its effect.

Cohort Studies↗

PubMed2003

Does retention matter? Treatment duration and improvement in drug use.

AIM: This study examines whether there is a minimum threshold, continuous or non-linear relationship between the duration of addiction treatment and improvements in drug use. DESIGN: Longitudinal cohort study of 62 drug treatment units and 4005 clients in the US National Treatment Improvement Evaluation Study, fielded from 1993 to 1995. SUBJECTS: Baseline and 1-year follow-up interviews with clients in methadone maintenance, out-patient non-methadone, short-term residential and long-term residential treatment programs. MEASURES: Improvement in drug use is the difference between the client-reported peak frequency of drug use (in days per month) in the year prior to the baseline interview minus the peak frequency in the year after discharge. Primary drug, and overall use of the major illicit drugs (heroin, cocaine powder, crack cocaine, and marijuana) are considered separately. RESULTS: Controlling for multiple factors, treatment duration had a positive linear relationship with primary drug use improvement among methadone clients and an inverted-U-shaped relationship with overall and primary drug use improvements among out-patient and long-term residential clients. Improvement with longer duration is greatest for long-term residential clients. CONCLUSIONS: Contrary to previous arguments for a sharp retention threshold for onset of treatment effects, we find smooth curves relating treatment duration to drug use improvements in methadone maintenance, out-patient non-methadone and long-term residential modalities. These relationships are effectively linear for durations typically observed in single treatment episodes, but unusually long retention in out-patient non-methadone and long-term residential units appear steadily less predictive of improvement.

Adolescent↗

PubMed2003

Effect of primary medical care on addiction and medical severity in substance abuse treatment programs.

OBJECTIVE: To examine whether the availability of primary medical care on-site at addiction treatment programs or off-site by referral improves patients' addiction severity and medical outcomes, compared to programs that offer no primary care. DESIGN: Secondary analysis of a prospective cohort study of patients admitted to a purposive national sample of substance abuse treatment programs. SETTING: Substance abuse treatment programs in major U.S. metropolitan areas eligible for demonstration grant funding from the federal Substance Abuse and Mental Health Services Administration. RESPONDENTS: Administrators at 52 substance abuse treatment programs, and 2,878 of their patients who completed treatment intake, discharge, and follow-up interviews. MEASUREMENTS: Program administrators reported whether the program had primary medical care available on-site, only off-site, or not at all. Patients responded to multiple questions regarding their addiction and medical status in intake and 12-month follow-up interviews. These items were combined into multi-item composite scores of addiction and medical severity. The addiction severity score includes items measuring alcohol and drug use, employment, illegal activities, legal supervision, family and other social support, housing, physical conditions, and psychiatric status. The medical severity score includes measures of perceived health, functional limitations, and comorbid physical conditions. MAIN RESULTS: After controlling for treatment modality, geographic region, and multiple patient-level characteristics, patients who attended programs with on-site primary medical care experienced significantly less addiction severity at 12-month follow-up (regression coefficient, -25.9; 95% confidence interval [95% CI], -43.2 to -8.5), compared with patients who attended programs with no primary medical care. However, on-site care did not significantly influence medical severity at follow-up (coefficient, -0.28; 95% CI, -0.69 to 0.14). Referral to off-site primary care exerted no detectable effects on either addiction severity (coefficient, -9.0; 95% CI, -26.5 to 8.5) or medical severity (coefficient, -0.03; 95% CI, -0.37 to 0.44). CONCLUSIONS: On-site primary medical care improves substance abuse treatment patients' addiction-related outcomes, but not necessarily their health-related outcomes. Further study is needed to discern the mechanism through which on-site primary care might improve the addiction-related outcomes of substance abuse treatment.

Adult↗

PubMed2003

[Applying randomized terminal linker-dependent PCR to detect the DNA damage of p53 gene in rat].

In order to use the technique of Randomized Terminal Linker-dependent PCR(RDPCR) to detect DNA lesions of specific gene in vivo, rats were administered with potassium dichromate by i.p. injection and genomic DNA of lung were extracted. Single-stranded products were made by repeated primer extension, these products were ligated to a linker and thus amplified by primer P2 and PL. The final PCR products were detected by electrophoresis and Southern hybridization with DIG-labeled probe. The results showed that two hybridization bands for extron 7 of p53 gene were found with dosage of 20.0 mg/kg and 40.0 mg/kg indicating the DNA lesions of extron 7 of p53 gene, by potassium dichromate and there were two DNA lesion cites. The findings from this study provide evidences both for further investigation of mutational mechanism of hexavalent chromium and expansion on using RDPCR in toxicology.

Animals↗

PubMed2002

Shedding of kidney injury molecule-1, a putative adhesion protein involved in renal regeneration.

KIM-1 (kidney injury molecule-1) is a type I transmembrane glycoprotein expressed on dedifferentiated renal proximal tubule epithelial cells undergoing regeneration after toxic or ischemic injury. The extracellular domain of KIM-1 is composed of an immunoglobulin-like domain topping a long mucin-like domain, a structure that points to a possible role in cell adhesion by homology to several known adhesion proteins. Two splice variants (a and b), of the human KIM-1 having identical extracellular domains, differ in their cytoplasmic domains and tissue distributions. In this study, we report that the KIM-1b transcript is expressed predominantly in adult human kidney. We describe the generation of 10 monoclonal antibodies against the extracellular domain of human KIM-1, the mapping of their binding sites, and their use in identifying various forms of the protein. We show that human KIM-1b is expressed in adult kidney cell lines, and we demonstrate that a soluble form of KIM-1 is shed constitutively into the culture medium of the cell lines expressing endogenous or recombinant KIM-1b by membrane-proximal cleavage. A monoclonal antibody that binds at or close to the proteolytic site can partially block the shedding of KIM-1. Release of soluble KIM-1 is enhanced by activating the cells with phorbol 12-myristate 13-acetate and can be inhibited with two metalloproteinase inhibitors, BB-94 (Batimastat) and GM6001 (Ilomastat), suggesting that the cleavage is mediated by a metalloproteinase. We propose that the shedding of KIM-1 in the kidney undergoing regeneration constitutes an active mechanism allowing dedifferentiated regenerating cells to scatter on denuded patches of the basement membrane and reconstitute a continuous epithelial layer.

Alternative Splicing↗

PubMed2002

Intravascular extraction of permanent pacemaker leads.

PURPOSE: Cardiac leads that became infected, fail, or are otherwise problematic present difficulties in the management of patients. In this report, we assess our intravascular countertraction technique. METHOD: Between February 1990 and January 2001, 13 leads were removed from 11 patients using the intravascular countertraction technique. The reasons for lead extraction were pacemaker infection and lead dysfunction. RESULTS: In two of these patients, the ventricular leads could not be completely removed. The complete success rate was 85% and the overall success rate was 92%. There were no serious complications such as cardiac rupture, vein injury, or death, and there were no clinical signs of pulmonary embolism. In one of the patients whose ventricular leads could not be removed completely, the ventricular lead was stretched from its previous round shape, but tricuspid valve regurgitation did not occur during the 3-year follow-up period. In the other patient, the distal electrode was left in the subclavian vein. However, this residual distal electrode did not migrate, and there were no clinical signs of any recurrence of infection. CONCLUSIONS: The present study suggests that to remove leads successfully, the largest locking stylet that can be easily passed to the lead's tip through the coil lumen should be chosen in order to avoid valve injury, which can sometimes occur when a ventricular lead's locking stylet is left in the coil lumen.

Aged↗

PubMedDate not supplied

Designated case managers as facilitators of medical and psychosocial service delivery in addiction treatment programs.

This study examines whether having designated case management staff facilitates delivery of comprehensive medical and psychosocial services in substance abuse treatment programs. A multilevel, prospective cohort study of 2829 clients admitted to selected substance abuse treatment programs was used to study clients from long-term residential, outpatient, and methadone treatment modalities. Program directors reported whether the program had staff designated as case managers. After treatment discharge, clients reported their receipt of 9 supplemental services during the treatment episode. In multivariate models controlling for multiple program-level and client-level factors, program-level availability of designated case managers increased client-level receipt of only 2 of 9 services, and exerted no effect on service comprehensiveness, compared to programs that did not have designated case managers. These findings do not support the common practice of designating case management staff as a means to facilitate comprehensive services delivery in addiction treatment programs.

Adolescent↗