McMaster University

About: McMaster University is a education organization based out in Hamilton, Ontario, Canada. It is known for research contribution in the topics: Population & Health care. The organization has 41361 authors who have published 101269 publications receiving 4251422 citations.

Discrete Cosine Transform: Algorithms, Advantages, Applications

Abstract: Discrete Cosine Transform. Definitions and General Properties. DCT and Its Relations to the Karhunen-Loeve Transform. Fast Algorithms for DCT-II. Two Dimensional DCT Algorithms. Performance of the DCT. Applications of the DCT. Appendices. References. Index.

Recommendations for Conduct, Methodological Practices, and Reporting of Cost-effectiveness Analyses: Second Panel on Cost-Effectiveness in Health and Medicine

Abstract: Importance Since publication of the report by the Panel on Cost-Effectiveness in Health and Medicine in 1996, researchers have advanced the methods of cost-effectiveness analysis, and policy makers have experimented with its application. The need to deliver health care efficiently and the importance of using analytic techniques to understand the clinical and economic consequences of strategies to improve health have increased in recent years. Objective To review the state of the field and provide recommendations to improve the quality of cost-effectiveness analyses. The intended audiences include researchers, government policy makers, public health officials, health care administrators, payers, businesses, clinicians, patients, and consumers. Design In 2012, the Second Panel on Cost-Effectiveness in Health and Medicine was formed and included 2 co-chairs, 13 members, and 3 additional members of a leadership group. These members were selected on the basis of their experience in the field to provide broad expertise in the design, conduct, and use of cost-effectiveness analyses. Over the next 3.5 years, the panel developed recommendations by consensus. These recommendations were then reviewed by invited external reviewers and through a public posting process. Findings The concept of a “reference case” and a set of standard methodological practices that all cost-effectiveness analyses should follow to improve quality and comparability are recommended. All cost-effectiveness analyses should report 2 reference case analyses: one based on a health care sector perspective and another based on a societal perspective. The use of an “impact inventory,” which is a structured table that contains consequences (both inside and outside the formal health care sector), intended to clarify the scope and boundaries of the 2 reference case analyses is also recommended. This special communication reviews these recommendations and others concerning the estimation of the consequences of interventions, the valuation of health outcomes, and the reporting of cost-effectiveness analyses. Conclusions and Relevance The Second Panel reviewed the current status of the field of cost-effectiveness analysis and developed a new set of recommendations. Major changes include the recommendation to perform analyses from 2 reference case perspectives and to provide an impact inventory to clarify included consequences.

Endoscopic assessment of oesophagitis: clinical and functional correlates and further validation of the Los Angeles classification.

Abstract: Background—Endoscopic oesophageal changes are diagnostically helpful and identify patients exposed to the risk of dis- ease chronicity. However, there is a seri- ous lack of agreement about how to describe and classify the appearance of reflux oesophagitis Aims—To examine the reliability of crite- ria that describe the circumferential ex- tent of mucosal breaks and to evaluate the functional and clinical correlates of pa- tients with reflux disease whose oesoph- agitis was graded according to the Los Angeles system. Methods—Forty six endoscopists from diVerent countries used a detailed work- sheet to evaluate endoscopic video record- ings from 22 patients with the full range of severity of reflux oesophagitis. In separate studies, Los Angeles system gradings were correlated with 24 hour oesophageal pH monitoring (178 patients), and with clini- cal trials of omeprazole treatment (277 patients). Results—Evaluation of circumferential extent of oesophagitis by the criterion of whether mucosal breaks extended be- tween the tops of mucosal folds, gave acceptable agreement (mean Œ value 0.4) among observers. This approach is used in the Los Angeles system. An alternative approach of grouping the circumferential extent of mucosal breaks as occupying 0-25%, 26-50%, 51-75%, 76-99%, or 100% of the oesophageal circumference, gave unacceptably high interobserver variation (mean Œ values 0-0.15) for all but the low- est category of extent (mean Œ value 0.4). Severity of oesophageal acid exposure was significantly (p<0.001) related to the se- verity grade of oesophagitis. Preteatment oesophagitis grades A-C were related to heartburn severity (p<0.01), outcomes of omeprazole (10 mg daily) treatment (p<0.01),and the risk for symptom relapse oV therapy over six months (p<0.05). Conclusions—Results add further support to previous studies for the clinical utility of the Los Angeles system for endoscopic grading of oesophagitis. (Gut 1999;45:172-180)

Telomere shortening associated with chromosome instability is arrested in immortal cells which express telomerase activity.

Abstract: Loss of telomeric DNA during cell proliferation may play a role in ageing and cancer. Since telomeres permit complete replication of eukaryotic chromosomes and protect their ends from recombination, we have measured telomere length, telomerase activity and chromosome rearrangements in human cells before and after transformation with SV40 or Ad5. In all mortal populations, telomeres shortened by approximately 65 bp/generation during the lifespan of the cultures. When transformed cells reached crisis, the length of the telomeric TTAGGG repeats was only approximately 1.5 kbp and many dicentric chromosomes were observed. In immortal cells, telomere length and frequency of dicentric chromosomes stabilized after crisis. Telomerase activity was not detectable in control or extended lifespan populations but was present in immortal populations. These results suggest that chromosomes with short (TTAGGG)n tracts are recombinogenic, critically shortened telomeres may be incompatible with cell proliferation and stabilization of telomere length by telomerase may be required for immortalization.