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Biomedical subjects

M Chung

Publications and source records attributed to M Chung.

At least 127 records · Page 7Linked to original sources
PubMed1994

The electrocardiographic effects of cetirizine in normal subjects.

OBJECTIVE: To establish whether the antihistamine cetirizine has the potential to prolong the QTc interval in normal volunteers at up to six times the usual recommended dose. METHODS: Twenty-five healthy volunteers were studied in a prospective, double-blind crossover design conducted on inpatients in a Clinical Research Center. The primary end point of the study was QTc prolongation on the surface electrocardiogram (ECG). Plasma concentrations of cetirizine were also measured for pharmacokinetic analysis. The end point for the pharmacokinetic analysis was the dose/area under the concentration-time curve (apparent clearance of an oral dose). The subjects received the following three treatments in random sequence: placebo, 20 mg/day cetirizine, and 60 mg/day cetirizine for 7 consecutive days. A series of baseline ECGs was recorded over 2 days before each treatment, while the subject receiving placebo. ECG effects of the treatments were then compared with the baseline ECGs. RESULTS: Analysis of variance showed no difference between the treatment groups (placebo, 20 mg cetirizine, and 60 mg cetirizine every day) in effect on QTc compared with baseline. A paired Student t test showed no difference in dose/area under the concentration-time curve between the 20 mg/day and 60 mg/day dosing groups at steady state. CONCLUSION: In healthy volunteers, cetirizine does not prolong the QTc interval at doses of up to six times the usual recommended dose.

Adult↗
PubMed1994

Hepatitis C virus-associated glomerulonephritis. Effect of alpha-interferon therapy.

Hepatitis C virus (HCV) infection may present as a primary glomerular disease. We report 34 adult patients who presented with proteinuria and had circulating anti-HCV antibodies. Primary risk factors included a history of intravenous drug abuse (56%) or blood transfusion (18%). Patients presented with nephrotic syndrome (71%) or with non-nephrotic proteinuria (29%) and had membranoproliferative or acute proliferative glomerulonephritis on renal biopsy. Signs of clinical liver disease were infrequent (18%), though elevated liver function tests were common (66%) and liver biopsy in 16 of 18 patients showed chronic active hepatitis. Cryoglobulinemia was frequent (59%), but only 44% had extrarenal manifestations. In 100% of cases tested, HCV RNA could be found in the serum or cryoprecipitates. Fourteen patients received interferon alpha for 6 to 12 months with a significant reduction in proteinuria but no improvement in renal function. A good clinical response correlated with disappearance of HCV RNA from the serum during treatment; however, relapse of viremia and renal disease was common after completing therapy. Evidence for HCV infection should be sought in all patients with primary glomerular disease. The optimal treatment strategy, however, remains to be defined.

Adult↗
PubMed1994

A new orphan member of the nuclear hormone receptor superfamily closely related to Rev-Erb.

We have isolated complementary DNA clones encoding a novel orphan member of the nuclear receptor superfamily, termed BD73. This protein shows strong amino acid sequence similarity to the previously described Rev-ErbA alpha. Unlike Rev-Erb, in which the opposite strand of the C-terminal coding region encodes the C-terminal portion of a variant thyroid hormone receptor isoform, the opposite strand of the C-terminal coding region of BD73 does not have any extensive open reading frames. BD73 messenger RNA is expressed in a wide variety of tissues and cell lines. In quiescent HepG2 cells, BD73 messenger RNA levels are strongly induced by planar aromatic antioxidants. Like Rev-Erb, BD73 binds as a monomer to a DNA sequence which consists of a specific A/T-rich sequence upstream of the consensus hexameric half-site specified by the P box of the DNA-binding domain. Amino acid sequence comparisons suggest that the A box sequence, which has been suggested to mediate monomer binding by other superfamily members, lies closer to the DNA-binding domain in BD73 and Rev-Erb than in other receptors. Under the conditions examined, neither BD73 nor Rev-Erb activated reporters containing multiple copies of their common binding site. Thus, these two orphans may require an as yet unidentified ligand or other signal for such activation. Together, BD73 and Rev-Erb define a subgroup of orphan receptors that bind as monomers to a half-site flanked by a specific and extended A/T-rich sequence.

Amino Acid Sequence↗
PubMed1994

Pharmacokinetics of desipramine coadministered with sertraline or fluoxetine.

The pharmacokinetic interactions of sertraline and fluoxetine with the tricyclic antidepressant desipramine were studied in 18 healthy male volunteers phenotyped as extensive metabolizers of dextromethorphan. Concentrations in plasma were determined after 7 days of desipramine (50 mg/day) dosing alone, during the 21 days of desipramine and selective serotonin reuptake inhibitor (SSRI) coadministration (fluoxetine, 20 mg/day; sertraline, 50 mg/day), and for 21 days of continued desipramine administration after SSRI discontinuation. Desipramine Cmax was increased 4.0-fold versus 31% and AUC0-24 was increased 4.8-fold versus 23% for fluoxetine versus sertraline, respectively, relative to baseline after 3 weeks of coadministration. Desipramine trough concentrations approached baseline within 1 week of sertraline discontinuation but remained elevated for the 3-week follow-up period after fluoxetine discontinuation. Concentrations of SSRIs and their metabolites correlated significantly with desipramine concentration changes (for fluoxetine/norfluoxetine, r = 0.94 to 0.96; p < 0.001; for sertraline/desmethylsertraline, r = 0.63; p < 0.01). Thus, sertraline had less pharmacokinetic interaction with desipramine than did fluoxetine at their respective, minimum, usually effective doses.

1-Naphthylamine↗
PubMed1993

Shared nuclear protein binding sites in the upstream region of the rat opsin gene.

DNase I protection and gel retardation assays have identified two sequences 5' to the rat opsin gene that interact with nuclear proteins from retina but not from a number of neuronal and non-neuronal tissues. These sites, Ret 2 and Ret 3, are over 1200 base pairs apart but seem to interact with the same protein(s). Synthetic oligonucleotides corresponding to each site were able to inhibit complex formation in a gel retardation assay using an oligonucleotide corresponding to the other site. The proteins binding to the Ret 2 and Ret 3 sites co-eluted in both ion exchange and gel filtration chromatography. The protein(s) were also present at adult levels at birth, suggesting that they may represent differentiation products expressed in the proliferating retinal epithelium.

Animals↗
PubMed1993

Perioperative blood transfusion and outcome after resection for colorectal carcinoma.

The degree of immunomodulation by perioperative blood transfusion and its effect on oncological surgery remain controversial. A major problem with previous clinical studies has been the inadequate patient population in each and the presence of confounding variables. To resolve some of the controversy, all studies published between 1982 and 1990 were reviewed using the statistical method of Mantel-Haentszel-Peto to determine a cumulative estimate of the direction and magnitude of this association. Some 20 papers were included in the analysis, representing 5236 patients. The cumulative odds ratios (95 per cent confidence interval) of disease recurrence, death from cancer and death from any cause were 1.80 (1.30-2.51), 1.76 (1.15-2.66) and 1.63 (1.12-2.38) respectively. These results support the hypothesis that perioperative blood transfusion is associated with an increased risk of recurrence of colorectal carcinoma and death from this malignancy.

Colorectal Neoplasms↗
PubMed1992

Inhibition of myogenesis by okadaic acid, an inhibitor of protein phosphatases, 1 and 2A, correlates with the induction of AP1.

Recently, we demonstrated that okadaic acid, an inhibitor of protein phosphatases 1 and 2A, inhibits myogenesis by extinguishing the expression of MyoD1 and inducing the expression of Id. Since it has been reported that transformation by c-fos also inhibits myogenesis through inhibition of MyoD1 expression, we examined the effects of okadaic acid on the activation of the c-fos and jun family of proto-oncogenes in an attempt to understand the mechanism by which okadaic acid inhibits the myogenic differentiation. Treatment of C2C12 cells in growth medium with okadaic acid increased expression of the mRNAs for the c-fos family continuously and for the jun family to a lesser extent. In contrast, in differentiation medium, the induction of c-fos, c-jun, and fos B mRNAs by okadaic acid was transient, whereas fra-1, jun D, and jun B mRNAs were induced continuously, suggesting that okadaic acid regulates the expression of the c-fos and jun family through complex regulatory mechanisms depending on the state of differentiation of the cells. Transfection of c-jun and c-fos promoter-chloramphenicol acetyltransferase constructs demonstrated that the effects of okadaic acid on the induction of c-fos and c-jun are mediated through the activation of promoter elements. These results suggest that some of the targets of protein phosphatases 1 and 2A may include transcription factors capable of forming AP1 complexes and that these factors may play an important role during myogenic differentiation.

Base Sequence↗
PubMed1991

Purification and partial characterization of stonustoxin (lethal factor) from Synanceja horrida venom.

1. The lethal factor of the stonefish (Synanceja horrida) venom, designated as the stonustoxin, was purified to homogeneity by a two-step procedure on Sephacryl S-200 High Resolution (HR) gel permeation and DEAE Bio-Gel A anion exchange chromatography. 2. Stonustoxin has a native mol. wt of 148,000 and an isoelectric point of 6.9. 3. SDS-polyacrylamide gel electrophoresis revealed two subunits (designated alpha and beta) with mol. wts of 71,000 and 79,000, respectively. 4. The amino acid composition of both subunits and the N-terminal amino acid sequence of the beta subunit were also determined. 5. Purified stonustoxin had an LD50 of 0.017 microgram/g which is 22-fold more potent than that of the crude venom. 6. The toxin exhibited potent haemolytic activity in vitro and edema-inducing activity with a minimum edema dose (MED) of 0.15 micrograms in mouse paw. The edema effect was not antagonized by diphenhydramine.

Amino Acid Sequence↗
PubMed1991

Screening for frailty: criteria and predictors of outcomes.

OBJECTIVE: To determine the reliability of rapid screening by clinically derived geriatric criteria in predicting outcomes of elderly hospitalized patients. DESIGN: Prospective cohort study of 985 patients screened at the time of hospital admission and followed for 1 year with respect to the outcomes of mortality, hospital readmission, and nursing home utilization. SETTING: Palo Alto Veterans Affairs Medical Center, a tertiary care teaching hospital. SUBJECTS: Male patients 65 years of age and older admitted to the Medical and Surgical services during the period from October 1, 1985 through September 30, 1986. RESULTS: Patients were grouped by specific screening criteria into three groups of increasing frailty: Independent, Frail, and Severely Impaired. Each criterion focused on a geriatric condition and was designed to serve as a marker for frailty. Increasing frailty was significantly correlated with increasing length of hospital stay (P less than 0.0001), nursing home utilization (P less than 0.0001), and mortality (P less than 0.0001). Multivariate analyses revealed that the clinical groups were more predictive of mortality and nursing home utilization than were age or Diagnosis-Related Groups (DRGs). Rehospitalization was unrelated to age, clinical group, or DRG, suggesting that utilization may not be driven by the clinical factors measured in this study. CONCLUSIONS: Rapid clinical screening using specific geriatric criteria is effective in identifying frail older subjects at risk for mortality and nursing home utilization. Our findings suggest that geriatric syndromes are more predictive of adverse outcomes than diagnosis per se. This well operationalized screening process is inexpensive as well as effective and could easily be introduced into other hospital settings.

Activities of Daily Living↗
PubMed1990

Effect of haemodialysis on the pharmacokinetics of cetirizine.

The pharmacokinetics of Cetirizine, a histamine H1-receptor antagonist, were investigated in five renal failure patients undergoing chronic haemodialysis therapy. The patients received one 10 mg cetirizine dihydrochloride capsule 3 h before haemodialysis. Concentrations of cetirizine in serum and dialysate were determined by HPLC. The maximum serum cetirizine concentration and the time to reach that maximum were 285 micrograms.l-1 and 2.0 h, respectively. The terminal disposition half-life of cetirizine in these patients was 19.3 h. The haemodialysis clearance of cetirizine was 14.0 ml. min-1. Although this is approximately 33% of the apparent total body clearance of cetirizine in subjects with normal renal function, the fraction of the dose removed by dialysis was only 9.4%. Thus, since haemodialysis does not produce a clinically significantly alteration in cetirizine elimination, no supplemental dose should be necessary after dialysis.

Adult↗
PubMed1989

Characterization of tumor necrosis factor-alpha receptors in human and rat thyroid cells and regulation of the receptors by thyrotropin.

Administration of recombinant human tumor necrosis factor-alpha (TNF) to rats and mice produces a model of nonthyroid illness in which there is impairment of hypothalamic-pituitary thyroid function, including reduced serum concentrations of T4 and T3, reduced thyroid radioiodine uptake, and reduced response to TSH. In this study, we tested the binding and effects of TNF on FRTL-5 cells and on four human thyroid carcinoma cell lines. The TSH-stimulated [125I]iodide uptake by FRTL-5 cells was inhibited by TNF in a dose-dependent manner. The four human thyroid carcinoma cell lines (NPA, MRO, ARO, WRO) have TSH receptors but did not respond to TSH in regard to iodide uptake and thymidine incorporation. Both human thyroid carcinoma cells and FRTL-5 cells contain specific receptors for TNF. Scatchard analysis showed that the receptor numbers and dissociation constants in human thyroid carcinoma cells and FRTL-5 cells were, respectively; 2.4 x 10(4), 5.4 nM (WRO); 8 x 10(3), 3.4 nM (MRO); 4 x 10(3), 1 nM (ARO); 7 x 10(3), 1 nM (NPA); 3 x 10(3), 1 nM (FRTL-5), and 9 x 10(3), 1 nM (FRTL-5 cells treated with TSH). The results indicate that TNF affects thyroid cell function through binding to the TNF receptor and that the number of TNF receptors is regulated by TSH.

Animals↗