Biomedical subjects

C C Cheng

Publications and source records attributed to C C Cheng.

184 records · Page 11Linked to original sources

PubMedDate not supplied

Solution conformation of a peptide corresponding to residues 151-172 of HIV-1 integrase using NMR and CD spectroscopy.

The solution structure of a synthetic peptide corresponding to residues 151-172 of HIV-1 integrase has been determined by NMR and CD spectroscopy. Residues 151-172 of HIV-1 integrase were predicted to be an alpha-helix and to be responsible for the oligomerization of HIV-1 integrase. Two-dimensional 1H NMR and CD studies indicate that this synthetic peptide adopts an amphipathic alpha-helical conformation in TFE-containing solution. However, concentration-dependent CD studies reveal that this peptide motif does not form dimers or oligomers in solution as predicted. These results are in agreement with the crystal structure of the catalytic domain of HIV-1 integrase reported recently.

Amino Acid Sequence↗

PubMedDate not supplied

CAPD-associated peritonitis caused by Alcaligenes xylosoxidans sp. xylosoxidans.

Alcaligenes xylosoxidans is an uncommon cause of peritonitis in patients on maintenance continuous ambulatory peritoneal dialysis (CAPD). Peritonitis caused by A. xylosoxidans usually carries a poor prognosis because of the pathogen's virulence and its universal resistance to most antimicrobial agents. Even after early Tenckhoff catheter removal, the transport property of the peritoneum is often irreversibly damaged, leading to permanent technique failure. We report 2 patients with CAPD-associated peritonitis due to A. xylosoxidans sp. xylosoxidans who were successfully cured with a combination of piperacillin and tazobactam. One of them subsequently returned uneventfully to CAPD.

Adult↗

PubMedDate not supplied

Electropharmacologic characteristics and radiofrequency catheter ablation of sustained ventricular tachycardia in patients without structural heart disease.

Twenty-six patients (mean age 39 +/- 17 years) with idiopathic sustained ventricular tachycardia (VT) were included for study. The patients were divided into two groups: group I: 14 patients with VT originating from the right ventricular outflow tract (wide QRS tachycardia with complete left bundle branch block pattern), and group II: 12 patients with VT originating from the left ventricle (wide QRS tachycardia with complete right bundle branch block pattern). Most of the group I patients (11/14) needed isoproterenol to facilitate induction of VT, and were sensitive to both verapamil and adenosine. Eight patients had successful radio-frequency (RF) ablation and were free of VT without any antiarrhythmic drugs. In group II, sustained VT was induced by programmed ventricular stimulation in all the patients (only 3 patients needed isoproterenol for facilitation); verapamil could terminate all the VT but none of the patients responded to adenosine. Eight patients received RF ablation and 6 patients had successful ablation without recurrent tachycardia on a long-term basis. Different sensitivity to adenosine and isoproterenol between right and left ventricular idiopathic VT suggested different underlying mechanisms for both types of VT. The patients who did not receive catheter ablation still had attacks of VT despite antiarrhythmic drug treatment; however, none of these patients had sudden death since the first attack of VT (mean 95 +/- 51 months), suggesting a benign prognosis in idiopathic VT.

Adolescent↗

PubMedDate not supplied

Delivery of anticancer drugs.

Chemotherapy is a major therapeutic approach for the treatment of both localized and metastasized cancers. Since anticancer drugs are neither specific nor targeted to the cancer cells, improved delivery of anticancer drugs to tumor tissues in humans appears to be a reasonable and achievable challenge. Scientists are working to increase the availability of drug for tumor uptake by 1) delaying the release preparations for long-lasting actions; 2) using liposome-entrapped drugs for prolonged effect or reduced toxicity; 3) administrating inert, non-toxic prodrugs for specific activation at the tumor site; 4) delivering the antibody-mediated drugs; or 5) conjugating site-specific carriers to direct the drug to the tumor target. The latter depends heavily on pharmacokinetic investigations. Some success has been achieved in enhancing the efficacy and reducing the toxicity of drugs. Pharmacokinetic and pharmacodynamic considerations are two areas which have been focused toward the quantitative pharmacological studies of anticancer drugs in this manuscript. This review covers biodistribution and elimination, furnishing information on body clearance and unveiling sites of major metabolism; administration of anticancer drugs via various routes for optimal utilization; intra-arterial infusion for localized tumors, intrathecal, intraperitoneal and intrapleural injection for regional cavity administration. Conventional delivery routes, doses, pharmacokinetics data and elimination routes of therapeutic anticancer drugs are tabled. General approaches for delivery of anticancer drugs in achieving therapeutic improvements are outlined and correlated. Mechanism of drug resistance, and specific changes affecting the delivery of available chemotherapeutic agents, as well as the drugs to restore the sensitivities to agents of resistant tumor cells, are discussed. This monograph covers the developments and progress in the delivery of anticancer drugs in two approaches: the theoretical approach, including pharmacokinetic and pharmacodynamic considerations, therapeutic implications and mechanism of drug resistance, and the practical approach, including the physical, chemical, biochemical and physiological considerations. Among these, the physical approach for the delivery of anticancer agents to target sites (via microparticulate drug carriers: nanoparticles, liposomes, microspheres and activated carbon as well as the magnetic microcapsules) has shown recognizable improvements in prolonging anticancer effects and reducing toxicities. Implantable pumps and reservoirs for regional chemotherapy provide external control of delivery rate. The implanted systems, in general, yield better results than the traditional treatments in the treatment of liver and brain cancer. Chemical approaches for the improvement of drug delivery use prodrugs, biodegradable polymers and macromolecular matrix techniques.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗