Biomedical subjects

Christopher Y Kim

Publications and source records attributed to Christopher Y Kim.

6 recordsLinked to original sources

PubMed2025

Assessment of mRNA Decay and Calculation of Codon Occurrence to mRNA Stability Correlation Coefficients after 5-EU Metabolic Labeling.

mRNA translation and decay are tightly connected. This chapter describes a method to assess the influence of each codon identity on mRNA stability in cultured cells. The technique involves metabolic labeling of the nascent mRNAs by addition of the nucleoside analog 5-ethynyluridine (5-EU), purification of the RNA at different time-points after chase of the 5-EU, then biotinylation with Click chemistry, pull-down, and sequencing. The transcripts' half-lives are calculated from the expression level of each mRNA at the different time-points. Finally, the method describes the calculation of the Codon occurrence to mRNA Stability correlation Coefficient, or CSC, as a correlation between the codon occurrence in a transcript and the transcript half-life, for each codon.

RNA Stability↗

PubMed2003

Cost-effectiveness of screening a population with chronic gastroesophageal reflux.

BACKGROUND: Persons with chronic esophageal reflux are at increased risk for the development of Barrett's esophagus and adenocarcinoma. Recently developed ultrathin endoscopes are less expensive and better tolerated than standard endoscopes, they can be used without sedation, and are sensitive and specific for Barrett's esophagus. The cost-effectiveness of one-time screening strategies were evaluated for 50-year-old patients with chronic reflux: no screening, standard endoscopy, and screening by an ultrathin endoscope. METHODS: Markov models were created to simulate the clinical course for patients with chronic reflux. Costs and quality-adjusted life-years were estimated from cancer registry data, published medical data, and expert opinion. RESULTS: Under baseline assumptions, no screening resulted in average costs of $11,785 per person and 19.3226 quality-adjusted life-years. Ultrathin endoscopy screening resulted in costs of $12,119 per person and 19.3326 quality-adjusted life-years, yielding a marginal cost-effectiveness ratio of $55,764 per quality-adjusted life-year. Using standard endoscopy yielded costs of $12,332 with only slightly greater effectiveness, yielding a marginal cost-effectiveness ratio of $709,260 when compared with ultrathin endoscopy and $86,833 compared with no screening. Results were most sensitive to variation in the incidence of cancer in the population with Barrett's esophagus. CONCLUSIONS: Screening for Barrett's esophagus with ultrathin endoscopy is more cost-effective than standard endoscopy, and both strategies appear to improve quality-adjusted life-years among patients with chronic reflux at costs that are similar to those of other accepted preventive measures.

Adenocarcinoma↗

PubMed2003

Accuracy of esophagoscopy performed by a non-physician endoscopist with a 4-mm diameter battery-powered endoscope.

BACKGROUND: A cost-effective technique is needed for screening of a broad population at risk for esophageal cancer. A solution would be to have non-physician endoscopists perform esophagoscopy with small-caliber battery-powered endoscopes. METHODS: In a prospective blinded study, the diagnostic accuracy of sedated esophagoscopy performed by a trained nurse practitioner with a battery-powered 4-mm diameter endoscope was compared with that for a sedated standard video-endoscopy performed by a gastroenterologist. Patients were recruited to undergo peroral esophagoscopy by the nurse practitioner followed by sedated standard endoscopy by the supervising gastroenterologist, each blinded to the findings of the other. Major esophageal findings of nurse practitioner and gastroenterologist were compared. RESULTS: Findings in 40 patients were analyzed. In 4 patients both endoscopists could not assess the presence or absence of columnar-lined esophagus because of severe erosive esophagitis (n = 3) or severe candida-esophagitis (n = 1). By using sedated standard endoscopy as the standard, on a per finding basis, esophagoscopy by the nurse practitioner had a sensitivity for columnar-lined esophagus of 89%: 95% CI [75%, 97%] and specificity of 96%: 95% CI [84%, 99%]. The missed columnar epithelium was a 3 x 3-mm island. For all lesions, the sensitivity of endoscopy performed by the nurse practitioner with the battery-powered endoscope was 75%: 95% CI [67%, 82%] and specificity 98%: 95% CI [96%, 99%]. The nurse practitioner missed all of 4 rings (3 considered clinically irrelevant). CONCLUSION: Esophagoscopy with a battery-powered 4-mm diameter endoscope by a non-physician endoscopist is feasible and accurate in detecting esophageal pathologies. It may be an efficient screening method for the detection of columnar-lined esophagus. There was a distinct underestimate of the presence of esophageal rings.

Barrett Esophagus↗

PubMed2002

High-resolution chromoendoscopy for classifying colonic polyps: a multicenter study.

BACKGROUND: Chromoendoscopy may reliably separate adenomatous from nonadenomatous polyps. The aim of this multicenter trial was to determine the accuracy of high-resolution chromoendoscopy for the determination of colonic polyp histology. METHODS: This multicenter trial included 4 academic centers and a primary care practice. In 299 patients referred for routine colonoscopy or sigmoidoscopy, 520 polyps 10 mm in size were sprayed with indigo carmine dye. Using a high-resolution endoscope, the endoscopist predicted the histology of each polyp based on its surface characteristics. Hyperplastic polyps had a "pitted" surface pattern of orderly arranged "dots" that resembled surrounding normal mucosa. Adenomatous polyps had at least one surface "groove" or "sulcus." Each polyp was subsequently resected for histopathologic evaluation. RESULTS: The resected polyps were comprised by 193 adenomas (37%), 225 hyperplastic polyps (43%), and 102 "other" types (20%). Forty polyps (7.7%) could not be classified by high resolution chromoendoscopy with indigo carmine dye. For the remaining polyps, the sensitivity, specificity, and negative predictive value of indigo carmine dye staining for adenomatous polyps were, respectively, 82%, 82%, and 88%. The results were consistent among the academic centers and the primary care practice. CONCLUSIONS: High-resolution chromoendoscopy with indigo carmine dye demonstrates morphologic detail of diminutive colorectal polyps that can reliably be used to separate adenomatous from nonadenomatous polyps.

Adenoma↗

PubMed2002

Endoscopic removal of large colonic lipomas.

BACKGROUND: Colonic lipomas are benign adipose tumors that rarely cause symptoms. Removal of lipomas 2 cm or greater in diameter has been associated with a greater risk of perforation. Experience with the evaluation and removal of large colonic lipomas with the assistance of EUS to reduce the risk of perforation is reported. METHODS: Four patients with large colonic lipomas were evaluated and treated with endoscopic methods. EUS was performed to confirm that the lesion was a lipoma superficial to the muscularis propria. Saline or epinephrine solution was injected at the base of the tumor, which was then resected electrosurgically with a snare. OBSERVATIONS: All 4 lesions were successfully removed and histopathologically confirmed to be lipomas (mean maximal diameter 2.8 cm). There were no complications of any procedure. One patient was hospitalized overnight because of abdominal pain that resolved without complication. CONCLUSIONS: Large colonic lipomas can be removed safely by electrosurgical snare resection after injection of the base with epinephrine or saline solution. EUS should be used to ensure that the lipoma does not extend into the muscularis propria. Clinical judgment is important in assessing the need to remove these lesions.

Adult↗

PubMed2002

U.S. veterans' experience with rebetron in a nonstudy environment: success or failure?

OBJECTIVE: The aim of this study is to report the clinical response observed in a U.S. veteran population with hepatitis C to combination therapy with Rebetron (interferon/ribavirin) outside of a controlled study environment. METHODS: Ninety-nine consecutive patients with hepatitis C who met the approved guidelines for treatment were offered treatment with Rebetron. Ninety-four patients initiated therapy. All patients received formal instruction on the use of the drug, as well as the side effects and were instructed to report any side effects. Follow-up was scheduled twice a month for the first month, then monthly unless adverse events were observed. RESULTS: Ninety-four of 99 patients initiated therapy. Thirty-two patients were lost to follow-up or did not tolerate therapy. Ethnic distribution comprised 56 whites, 42 African Americans, one Hispanic. Of the 56 whites who started therapy, 39 completed treatment. Sustained viral response (SVR) for all genotypes was observed in 10 of 39 (26%). In the African American patients, 22 of 42 (52%) completed therapy, but a SVR was noted in none. The only Hispanic patient did not respond to therapy. In the veteran population, favorable factors associated with achieving SVR included having genotype other than 1, absence of cirrhosis, and ethnicity. Factors contributing to the low response rates were difficulty in adhering to therapy as well as a predominance of genotype 1. CONCLUSIONS: Using an intention-to-treat analysis, only 10% of veterans achieved SVR. These findings highlight the need to develop a multidisciplinary team to address the complexity of treating the veteran patient with hepatitis C.

Adult↗