Biomedical subjects

S F Chang

Publications and source records attributed to S F Chang.

130 records · Page 8Linked to original sources

PubMedDate not supplied

The suppression effect of DNA sequences within the C4A region on the transcription activity of human CYP21.

Two CYP21 genes, the active CYP21 and the pseudogene, CYP21P, also pairs of duplicated genes including the XA, XB, XB-S; YA, YB; and ZA, ZB are arranged in tandem next to the serum complement C4 genes (C4A and C4B). In this report, we have analyzed the influence of some DNA sequences within the C4A/CYP21P region on the transcription activity of the human CYP21. After transiently transfecting the plasmid constructs into mouse adrenocarcinoma Y1 cells, mouse testis Leydig tumor MA10 cells and human liver tumor HepG2 cells, our results showed that sequences located within the -13943/-13174 and -3278/-2586 regions upstream from the CYP21P had suppression effects on the promoter activity of human CYP21. However, the short sequences spanning from -8415/-8373 and -4511/-4140 upstream from the CYP21P did not alter the basal transcription activity of the CYP21 gene. Our results indicated that specific sequences within the C4A region might function as suppressor-like elements for the transcription of human CYP21.

Adrenal Cortex↗

PubMedDate not supplied

Performance of a new transdermal nitroglycerin adhesive patch formulation.

This two-period crossover study in 24 healthy men compared the transdermal absorption of nitroglycerin from a new 20-cm2 nitroglycerin adhesive transdermal patch applied for a single 24-hour period (q24hr) with that from one inch of 2% nitroglycerin ointment applied over a 50-cm2 area every eight hours (q8hr) during a single 24-hour period. The observed differences in pharmacokinetic parameters were expected, based on product design (q24hr vs q8hr) and surface area (20 cm2 vs 50 cm2); however, when corrected for surface area, the mean plasma AUC ratios indicated that the patch delivered about 1.5 times more drug than the ointment. The patch delivery of nitroglycerin was confirmed by patch residual results, which indicated nitroglycerin was released at a rate of 0.75 mg/cm2/24 hrs. The patch exhibited good skin adhesion throughout the 24-hour application period.

Administration, Cutaneous↗

PubMedDate not supplied

Biotransformation and elimination of 14C-flecainide acetate in humans.

The metabolism of 14C-flecainide acetate, a new antiarrhythmic, was investigated in four healthy human subjects, after a single, 200-mg oral dose. The cumulative recovery of radioactivity ranged from 81 to 90% (mean, 86%) in urine and from 4 to 6% (mean, 5%) in feces; thus, flecainide does not appear to undergo extensive biliary excretion, unless reabsorption occurs after biliary elimination. The cumulative excretion in urine of unchanged flecainide ranged from 35 to 50% (mean, 42%) of the dose and was essentially complete by 72 hr postdose. Peak plasma levels of radioactivity (524 to 848 ng eq/ml) and of unchanged flecainide (214 to 281 ng/ml) were attained at 2 to 3 hr postdose. The average half-life for the disappearance of unchanged flecainide from plasma was about 16 hr; disappearance of total metabolites from plasma was only slightly slower. Radiomonitored TLC analysis showed that urine contained two major metabolites and two or three minor ones; both major metabolites were extensively conjugated. By TLC, NMR, and mass spectral comparisons to reference compounds, the two major urinary metabolites were shown to be meta-O-dealkylated flecainide and the meta-O-dealkylated lactam of flecainide. Most of the radioactivity in urine was accounted for by flecainide and the two major metabolites.

Adult↗

PubMedDate not supplied

Stroke incidence in Ilan, Taiwan.

The purpose of this community hospital-based study of stroke was to assess the incidence rate of cerebral infarct, cerebral hemorrhage, and subarachnoid hemorrhage in a well-defined region of South Ilan. A prospective stroke registry was established at the two regional general hospitals serving about 184,000 inhabitants. From January to December 1991, a total of 258 stroke events were registered. Computed tomography was done in 99% of the stroke cases. The mean age for first-ever stroke in the region was 66.1 +/- 12.2 years. The annual incidence rates per 1,000 population for first-ever cerebral infarct in the respective age groups were 0.75 (45-54 years), 1.59 (55-64 years), 5.24 (65-74 years) and 8.01 (> or = 75 years). The incidence rates per 1,000 population for first-ever cerebral hemorrhage in the respective age groups were 0.52 (45-54 years), 1.19 (55-64 years), 1.05 (65-74 years) and 2.91 (> or = 75 years). The incidence rates per 1,000 population for first-ever subarachnoid hemorrhage in the respective age groups were 0.17 (45-54 years), 0.20 (55-64 years), 0.12 (65-74 years) and 1.21 (> or = 75 years). The age-specific incidence rate for first-ever stroke in the group aged 45 to 54 years observed in this study is higher than that in Western countries. The age-adjusted incidence rate for cerebral hemorrhage is significantly higher than that in Caucasians and is similar to that reported in Japan from 1974 to 1983.

Aged↗