Search PubMed⌕ Search

Biomedical subjects

R Yang

Publications and source records attributed to R Yang.

At least 271 records · Page 15Linked to original sources
PubMed1983

Interferon activity produced by interferon messenger RNA in Tilapiamosaiabica peters oocytes.

The activities of interferon mRNA from various types of mouse cells have been studied using Tilapiamosaiabica peters oocytes (TPO) as the translation system. The translation activity of interferon mRNA in TPO was also compared with that in Xenopus laevis oocytes (XLO). The results obtained showed similar translation efficiency in both systems. The highest translation efficiency was observed when T. peters oocytes, microinjected with mRNA, were cultivated in Eagle's medium containing 0.01% HEPES and 0.5% NaHCO3 (pH 7.5) at 25 degrees C. pppA2' P5' A2' P5' A in concentration of 500 nM did not affect the translation of interferon mRNA in oocytes, but inhibition was demonstrated at 1 microM. A linear relationship was found between the amount of interferon mRNA injected and the antiviral activity of the translation products, suggesting that the amount of interferon mRNA can be determined by assaying the interferon activity of its translation product.

Adenine Nucleotides↗
PubMed1982

Peak homogeneity determination for the validation of high-performance liquid chromatographic assay methods.

To validate high-performance liquid chromatographic assay procedures with regard to specificity, methods were developed to determine the homogeneity of the chromatographic peaks. These methods employed a rapid-scanning UV-visible spectrophotometer to monitor the chromatographic effluent. The absorption data were processed to nullify the signal due to the drug substances specifically, while allowing the detection of coincident impurities. Results from three model systems indicated the ability of these methods to detect as little as 0.1% of a coincident impurity.

Biotransformation↗
PubMedDate not supplied

Extraordinary hyperconjugation of the methyl group in the S(1) state of 8-methylquinoline.

8-Methylquinoline is unique among the monomethylquinolines in the red-shift it shows in the absorption band derived from the short axis polarized ((1)L(a) <-- (1)A) electronic transition, relative to that in quinoline itself. The effect is even more pronounced in the 8-methylquinolinium cation, with the (1)L(a) band clearly emerging on the long-wavelength side of the (1)L(b) band, which is normally the longest wavelength absorption band in quinolines substituted with weakly interacting functional groups. The fluorescences of 8-methylquinoline and its conjugate acid show a pH dependence which is typical of N-heterocylic bases that undergo hydrolysis in the lowest excited singlet state. These observations are explained in terms of hyperconjugation in the lowest excited singlet state, with electronic charge being swept into the quinoline ring by coupling of the short-axis polarized transition of the ring system with the electrons of the methyl group in the 8-position of the ring.

Hydrogen-Ion Concentration↗
PubMedDate not supplied

Adequacy of disposable biopsy forceps for gastrointestinal endoscopy: a direct comparison with reusable forceps.

Disposable plastic biopsy forceps were compared prospectively to reusable stainless steel forceps. Thirty consecutive patients underwent a total of 249 biopsies, 124 with the disposable forceps, and 125 with reusable forceps. Biopsy locations included the esophagus, stomach, small intestine, colon, and common bile duct. Specimens were compared microscopically to determine overall surface area, depth, adequacy, and diagnostic result. The disposable biopsy forceps yielded specimens which were 37% smaller when compared with the reusable forceps. In five of the comparisons, minor differences in histological findings were noted between the two groups of biopsy specimens, but these differences did not alter the pathological diagnosis. However, in three cases in which superficial specimens were obtained, an underlying carcinoma was missed with the disposable forceps. Our study documents the utility of disposable biopsy forceps for mucosal lesions. In addition, there were 11 mechanical failures in 38 biopsy attempts with the plastic biopsy forceps. These forceps appear to be limited in their capacity to obtain adequate specimens from firm tissue or when submucosal biopsy samples are required, and they will require refinements in design to duplicate specimen quality obtained by traditional reusable forceps. Disposable forceps are particularly suitable for biopsy of mucosal lesions in patients with possible communicable disease, and they should help to reduce cross-contamination in the gastroenterology laboratory.

Biopsy↗
PubMedDate not supplied

Randomized, prospective trial of direct current versus bipolar electrocoagulation for bleeding internal hemorrhoids.

Fifty patients with bleeding internal hemorrhoids unresponsive to 6 weeks of standard medical therapy were randomly assigned to receive treatment with direct current or bipolar electrocoagulation. Treatment groups were similar in bleeding severity and internal hemorrhoid grade. Treatment sessions were significantly longer for direct current electrocoagulation (8.8 +/- 0.2 minutes) than for bipolar electrocoagulation (0.1 +/- 0.03 minutes) (p < 0.001). When compared to the bipolar electrocoagulation group, direct current electrocoagulation patients had more procedural pain that terminated therapy (5 of 25 patients [20%] versus 0 of 25 [0%], for a difference of 20% [95% confidence interval, 4% to 36%]; p = 0.05) and prolonged pain after the procedure (4 of 25 patients [16%] versus 1 of 25 [4%], for a difference of 12% [95% confidence interval, -4% to 28%]; p = 0.35). However, more post-treatment rectal ulcerations were seen in the bipolar electrocoagulation-treated group (6 of 25 patients [24%] versus 1 of 25 [4%], for a difference of 20% [95% confidence interval, 2% to 38%]; p = 0.10). Treatment groups did not differ in number of treatment sessions or months of follow-up. The rates of success, defined as obliteration of the hemorrhoids or cessation of bleeding with reduction of the hemorrhoids to grade 1 or less, for the direct current electrocoagulation and the bipolar electrocoagulation groups were 88% and 92%, respectively. Failures in the direct current electrocoagulation group were uncontrollable bleeding (n = 1) and refusal to continue therapy because of pain (n = 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Analysis of gene expression patterns of ovarian cancer cell lines with different metastatic potentials.

The objective of this study was to investigate the key genetic changes and molecular mechanisms in the process of invasion and metastasis of human epithelial ovarian cancers. The in vitro invasion assay was used to further testify that the human epithelial ovarian cancer cell line SKOV3.ip1 is more invasive and metastatic compared with its parental line SKOV3. A total of 17,000 human genome complementary DNA microarrays were used to compare the gene expression patterns of the two cell lines. Reverse transcription-polymerase chain reactions and Western blotting were performed to validate the results of the microarray. Totally, 1557 twofold differentially expressed genes were screened out by 17,000 human genome complementary DNA microarrays between the two cell lines, including some important genes such as, nm23, c-erbB-2, and other unknown genes or expressed sequence tags with remarkable fold changes. The results of the microarray experiment were further confirmed by reverse transcription-polymerase chain reactions and Western blotting of the nm23-H2 gene. SKOV3.ip1 is more invasive and metastatic than its parental line. The invasion and metastasis mechanism of epithelial ovarian cancer is a very complex process in which many important genes like nm23, c-erbB-2, as well as other unknown genes or expressed sequence tags were involved.

Base Sequence↗