Biomedical subjects

Kerry Lee

Publications and source records attributed to Kerry Lee.

5 recordsLinked to original sources

PubMed2004

Working memory and literacy as predictors of performance on algebraic word problems.

Previous studies on individual differences in mathematical abilities have shown that working memory contributes to early arithmetic performance. In this study, we extended the investigation to algebraic word problem solving. A total of 151 10-year-olds were administered algebraic word problems and measures of working memory, intelligence quotient (IQ), and reading ability. Regression results were consistent with findings from the arithmetic literature showing that a literacy composite measure provided greater contribution than did executive function capacity. However, a series of path analyses showed that the overall contribution of executive function was comparable to that of literacy; the effect of executive function was mediated by that of literacy. Both the phonological loop and the visual spatial sketchpad failed to contribute directly; they contributed only indirectly by way of literacy and performance IQ, respectively.

Child↗

PubMed2004

Recognition memory for studied words is determined by cortical activation differences at encoding but not during retrieval.

Prior work has shown that when responses to incidentally encoded words are sorted, subsequently remembered words elicit greater left prefrontal BOLD signal change relative to forgotten words. Similarly, low-frequency words elicit greater activation than high-frequency words in the same left prefrontal regions, contributing to their better subsequent memorability. This study examined the relative contribution of encoding and retrieval processes to the correct recognition of target words. A mixture of high- and low-frequency words was incidentally encoded. Scanning was performed at encoding as well as during retrieval. During encoding, greater activation in the left prefrontal and anterior cingulate regions predicted a higher proportion of hits for low-frequency words. However, data acquired during recognition showed that word frequency did not modulate activation in any of the areas tracking successful recognition. This result demonstrates that under some circumstances, the recognition of studied words is determined purely by processes that are active during encoding. In contrast to the finding for hits, activation associated with correctly rejected foils was modulated by word frequency, being higher for high-frequency words in the left lateral parietal and anterior prefrontal regions. These findings were replicated in two further experiments, one in which the number of test items at recognition was doubled and another where encoding strength for high-frequency words was varied (once vs. 10 times). These results indicate that word frequency modulates activity in the left lateral parietal and anterior prefrontal regions contingent on whether the item involved is correctly recognized as a target or a foil. This observation is consistent with a dual process account of episodic memory.

Adult↗

PubMed2003

Death in patients with permanent pacemakers for sick sinus syndrome.

BACKGROUND: Although more than one million patients in the United States have permanent pacemakers, little is known about their cause of death. We evaluated the cause of death in 404 patients who died in the Mode Selection Trial (MOST). METHODS: In MOST, patients received a dual-chamber pacemaker randomly programmed to either dual-chamber or ventricular pacing. The circumstances surrounding each death were reviewed by a clinical events committee, which used prospectively defined criteria to adjudicate the cause of death. RESULTS: A total of 2010 patients with a median age of 74 years were included. After a median follow-up of 33 months, 404 (20%) patients died, including 198 (49%) of noncardiac causes and 143 (35.4%) of cardiac causes. In 63 patients, the cause of death was unknown. Independent predictors of death through the use of a multivariable analysis were (1) demographic factors including age, male sex, and weight; (2) clinical factors including prior myocardial infarction, cardiomyopathy, New York Heart Association class III/IV, and the Charlson Comorbidity Index; and (3) scores from two measures of functional status, the Karnofsky Score and the Mini-Mental State Examination. Independent predictors of cardiovascular death were similar. CONCLUSIONS: Patients treated with permanent pacemakers for sinus node dysfunction are elderly and have a substantial mortality rate, with more than half the classifiable deaths being noncardiac. Baseline demographic variables and scores from quality-of-life measures can identify patients with the highest risk of death.

Age Distribution↗

PubMed2002

Identification of Src transformation fingerprint in human colon cancer.

We used a classical rodent model of transformation to understand the transcriptional processes, and hence the molecular and cellular events a given cell undergoes when progressing from a normal to a transformed phenotype. Src activation is evident in 80% of human colon cancer, yet the myriad of cellular processes effected at the level of gene expression has yet to be fully documented. We identified a Src 'transformation fingerprint' within the gene expression profiles of Src-transformed rat 3Y1 fibroblasts demonstrating a progression in transformation characteristics. To evaluate the role of this gene set in human cancer development and progression, we extracted the orthologous genes present on the Affymetrix Hu95A GeneChip (12k named genes) and compared expression profiles between the Src-induced rodent cell line model of transformation and staged colon tumors where Src is known to be activated. A similar gene expression pattern between the cell line model and staged colon tumors for components of the cell cycle, cytoskeletal associated proteins, transcription factors and lysosomal proteins suggests the need for co-regulation of several cellular processes in the progression of cancer. Genes not previously implicated in tumorigenesis were detected, as well as a set of 14 novel, highly conserved genes with here-to-fore unknown function. These studies define a set of transformation associated genes whose up-regulation has implications for understanding Src mediated transformation and strengthens the role of Src in the development and progression of human colon cancer. Supportive Supplemental Data can be viewed at http://pga.tigr.org/PGApubs.shtml.

Animals↗

PubMed2002

Biphasic versus monophasic shock waveform for conversion of atrial fibrillation: the results of an international randomized, double-blind multicenter trial.

OBJECTIVES: This study compared a biphasic waveform with a conventional monophasic waveform for cardioversion of atrial fibrillation (AF). BACKGROUND: Biphasic shock waveforms have been demonstrated to be superior to monophasic shocks for termination of ventricular fibrillation, but data regarding biphasic shocks for conversion of AF are still emerging. METHODS: In an international, multicenter, randomized, double-blind clinical trial, we compared the effectiveness of damped sine wave monophasic versus impedance-compensated truncated exponential biphasic shocks for the cardioversion of AF. Patients received up to five shocks, as necessary for conversion: 100 J, 150 J, 200 J, a fourth shock at maximum output for the initial waveform (200 J biphasic, 360 J monophasic) and a final cross-over shock at maximum output of the alternate waveform. RESULTS: Analysis included 107 monophasic and 96 biphasic patients. The success rate was higher for biphasic than for monophasic shocks at each of the three shared energy levels (100 J: 60% vs. 22%, p < 0.0001; 150 J: 77% vs. 44%, p < 0.0001; 200 J: 90% vs. 53%, p < 0.0001). Through four shocks, at a maximum of 200 J, biphasic performance was similar to monophasic performance at 360 J (91% vs. 85%, p = 0.29). Biphasic patients required fewer shocks (1.7 +/- 1.0 vs. 2.8 +/- 1.2, p < 0.0001) and lower total energy delivered (217 +/- 176 J vs. 548 +/- 331 J, p < 0.0001). The biphasic shock waveform was also associated with a lower frequency of dermal injury (17% vs. 41%, p < 0.0001). CONCLUSIONS: For the cardioversion of AF, a biphasic shock waveform has greater efficacy, requires fewer shocks and lower delivered energy, and results in less dermal injury than a monophasic shock waveform.

Adult↗