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Biomedical subjects

K L Lee

Publications and source records attributed to K L Lee.

At least 127 records · Page 7Linked to original sources
PubMed1993

Thrombolytic therapy for women with myocardial infarction: is there a gender gap? Thrombolysis and Angioplasty in Myocardial Infarction Study Group.

OBJECTIVES: The goal of this study was to investigate whether female gender portends an adverse prognosis independent of the severity of the underlying disease after acute myocardial infarction treated by thrombolysis. A total of 348 women were compared with 1,271 men enrolled in the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) trials. BACKGROUND: The reasons for gender differences in the management and prognosis of acute coronary artery syndromes remain poorly defined. The extent to which gender itself explains observed differences in outcome and use of diagnostic procedures remains unclear because confounding factors have not been specified. METHODS: Patients < 76 years of age presenting within 6 h of onset of ischemic symptoms with electrocardiographic ST segment elevation and without contraindications to thrombolysis, previous infarction in the same distribution or cardiogenic shock were prospectively enrolled in Phases 1 to 3, 5 and 7 of the TAMI trials. All patients received recombinant tissue-type plasminogen activator, urokinase or a combination of both agents. Protocol-mandated cardiac catheterization was performed during the hospital period. Rescue coronary angioplasty was carried out for reperfusion failure at angiography 90 min after initiation of thrombolytic therapy. Coronary artery bypass grafting or coronary angioplasty was performed for clinical indications. RESULTS: Women were older than men (61.0 +/- 9.7 vs. 55.8 +/- 10.1 years, mean +/- SD) and had a higher incidence of many risk factors for adverse outcome after myocardial infarction. There were no differences in baseline hemodynamic variables or time to thrombolytic treatment. Rates of acute and predischarge infarct-related artery patency and global and regional left ventricular function were similar in the two groups. Rates of in-hospital coronary angioplasty (52.6% and 54.1%) and bypass graft surgery (20.4% and 22.0%) were comparable in women and men, respectively. Women had higher unadjusted rates of mortality (9.2% vs. 5.4%, p = 0.014), reinfarction (6.4% vs. 2.6%, p = 0.005) and hemorrhagic stroke (2.0% vs. 0.55%, p = 0.017) than did men during the hospital period. When adjusted for clinical and angiographic variables, differences in mortality and hemorrhagic stroke did not reach statistical significance, and the risk of reinfarction was only marginally associated with gender. CONCLUSIONS: In selected patients undergoing thrombolytic therapy and cardiac catheterization for acute myocardial infarction, adjusted mortality rates and utilization of postlysis revascularization are similar in women and men. However, women may be at increased risk for reinfarction.

Age Factors↗
PubMed1993

Systolic left ventricular function after reperfusion therapy for acute myocardial infarction. Analysis of determinants of improvement. The TAMI Study Group.

BACKGROUND: Contrast ventriculograms of 542 patients treated with intravenous thrombolytic agents for acute myocardial infarction were examined to define changes in left ventricular ejection fraction and regional wall motion that occur during the first week after reperfusion therapy for acute myocardial infarction and define clinical, acute angiographic and treatment variables related to improvement in global and regional left ventricular function. METHODS AND RESULTS: Intravenous tissue-type plasminogen activator and/or urokinase was administered to 805 patients during acute myocardial infarction. Mean time from symptom onset to thrombolytic therapy was 3 hours (22 patients received therapy within the first hour). Acute and 7-day catheterization were performed. Paired left ventricular ejection fraction and centerline regional wall motion were available in 542 patients (67%). Stepwise, multivariable analysis of clinical, acute angiographic and treatment variables was used to develop two models: One related to improvement in left ventricular ejection fraction, and the second related to improvement in infarct zone regional function. Left ventricular ejection fraction did not change (51.2 +/- 11.1% for acute versus 51.9 +/- 11.0% for 1 week, p = 0.19). Improvement in infarct zone regional function was modest (14%) at 1 week (-2.54 +/- 1.07 standard deviation per chord for acute versus -2.17 +/- 1.24 at 1 week, p < 0.001). Subgroup analysis demonstrated modest improvement in ejection fraction (1.4 +/- 9.5%) and greater improvement in infarct zone function (19%) in patients with successful sustained reperfusion at 1 week. Depressed left ventricular ejection fraction and infarct zone regional wall motion at the acute study were strongly associated with improvement of these parameters at 1 week. Resolution of chest pain before acute catheterization, infarct-related artery flow at acute catheterization, and depressed regional wall motion in the noninfarct zone were associated with improvement in both ejection fraction and regional infarct zone function at 1 week. Notably, the time from the onset of symptoms to initiation of thrombolytic treatment was not related to subsequent improvement in ventricular function. CONCLUSIONS: Dramatic improvement in left ventricular systolic function is not common after thrombolytic therapy for acute myocardial infarction. Improvement in global and regional systolic function is most closely related to acutely depressed ventricular function and successful acute coronary recanalization. Thus, patients with the most myocardium in jeopardy and successful coronary reperfusion demonstrate the greatest improvement in global and infarct zone ventricular function. Overall, the magnitude of this improvement is modest, suggesting that the benefits of coronary reperfusion are not solely related to improvement in systolic left ventricular function.

Aged↗
PubMed1993

Continuous 12-lead ST-segment recovery analysis in the TAMI 7 study. Performance of a noninvasive method for real-time detection of failed myocardial reperfusion.

BACKGROUND: If a practical, reliable, noninvasive marker of failed reperfusion was available in real time, the benefits of further therapy in this patient subgroup could be tested. We developed a method of 12-lead ST-segment recovery analysis using continuously updated reference points to provide such a marker. METHODS AND RESULTS: In this study, our method was prospectively tested in 144 patients given thrombolytic therapy early in myocardial infarction. All patients had 12-lead continuous ST-segment monitoring and acute angiography, each analyzed in an independent, blinded core laboratory. ST-segment recovery and re-elevation were analyzed up to the moment of angiography, at which time patency was predicted. Predictions were correlated to angiographic infarct artery flow, with TIMI flow 0 to 1 as occluded and TIMI flow 2 to 3 as patent. Infarct artery occlusion was seen on first injection in 27% of patients. The positive predictive value of incomplete ST recovery or ST re-elevation by our method was 71%, negative predictive value 87%, with 90% specificity and 64% sensitivity for coronary occlusion. ST recovery analysis predicted patency in 94% of patients with TIMI 3 flow versus 81% of patients with TIMI 2 flow and predicted occlusion in 57% of patients with collateralized occlusion versus 72% of patients with non-collateralized occlusion. In a regression model including other noninvasive clinical descriptors, ST recovery alone contained the vast majority of predictive information about patency. CONCLUSIONS: In a blinded, prospective, angiographically correlated study design, 12-lead continuous ST-segment recovery analysis shows promise as a practical noninvasive marker of failed reperfusion that may contribute substantially to currently available bedside assessment. Our data also suggest that patients with TIMI 2 flow or with collateralized occlusions may represent a physiological spectrum definable with ST-segment recovery analysis.

Adolescent↗
PubMed1993

Improving oral health through understanding the meaning of health and disease in a Chinese culture.

Advances in modern technology have undoubtedly been of benefit to dentistry in its preventive and curative activities for populations worldwide. Studies, mainly from Western societies, show nonetheless that utilisation of services or adoption of preventive methods are not taken up at satisfactory levels. The focus of this paper is on the special problems in a Chinese society where major differences exist between the traditional lay health concepts and the modernised professional ones. Traditional Chinese health concepts comprise the balance between and interaction of 'Yin' and 'Yang', the vital forces in both the universe and in man's body, as the basis for maintaining health. To restore a disturbed equilibrium of vital forces, which will manifest itself as disease, a range of dietary products are available in Hong Kong, for example cooling herb tea to reduce fire from the stomach producing gum disease. Seeking dental treatment from dentists could be delayed or made 'unnecessary' due to reliance on home remedies. This could reduce the effectiveness of any planned health education activities and dental services available for improving the oral health status of the community according to prevailing Western concepts. An understanding of the cultural meaning of dental disease is fundamental to changing beliefs and attitudes of people in order to improve the oral health of the community.

Attitude to Health↗
PubMed1992

Insulin increases transcription of rat gene 33 through cis-acting elements in 5'-flanking DNA.

Gene 33 is a multihormonally-regulated rat gene whose transcription is rapidly and markedly enhanced by insulin in liver and cultured hepatoma cells. To examine the mechanism by which insulin regulates transcription, we have constructed chimeric plasmids in which expression of the bacterial cat gene, encoding chloramphenicol acetyltransferase (CAT), is governed by gene 33 promoter elements and contiguous sequences in DNA flanking the transcription start point (tsp). When transfected into H4IIE hepatoma cells, these constructs gave rise to stably transformed cell lines producing the bacterial CAT enzyme. This expression was increased by insulin treatment in a fashion resembling the effect of this hormone on transcription of the native gene. In vitro transcription assays in nuclear extracts also revealed increased transcription of the chimeric plasmids when the extracts were prepared from insulin-treated rat hepatoma cells. The results demonstrate that induction by insulin is mediated by cis-acting nucleotide sequences located between bp -480 to +27 relative to the tsp.

Animals↗
PubMed1992

Referral patterns for coronary artery disease treatment: gender bias or good clinical judgment?

OBJECTIVE: To determine whether a gender bias exists in referral for coronary bypass graft surgery among patients with catheterization-documented coronary artery disease. DESIGN: Historical cohort study (1969 to 1984). SETTING: A referral medical center. PATIENTS: A total of 5795 patients with catheterization-documented coronary artery disease. MEASUREMENTS: Surgical referral patterns of men and women grouped by risk for cardiac death and by treatment effectiveness. Time trends were evaluated for three periods: 1969 to 1974, 1975 to 1979, and 1980 to 1984. RESULTS: Overall, when no adjustment was made for baseline risk for cardiac death, no statistical difference was found between men and women regarding referral for surgery (46% compared with 44%, respectively). When an adjustment was made for such risk, the male-to-female odds ratio for surgical referral was 1.28 (95% Cl, 1.05 to 1.58) among patients with a low risk for cardiac death. This effect was most evident in the 1980 to 1984 period (odds ratio, 1.73; Cl, 1.29 to 2.31). In the high-risk group, the odds ratio was 0.84 (Cl, 0.68 to 1.04), with little change occurring during the study. Men were more likely to be referred for surgery when surgery offered the least survival benefit relative to medical therapy (odds ratio, 1.29; Cl, 1.08 to 1.54). This effect was most pronounced in the 1980 to 1984 period (odds ratio, 1.63; Cl, 1.27 to 2.10). CONCLUSIONS: Women are less likely than men to be referred for coronary bypass graft surgery among patients with a low risk for cardiac death, in whom surgery offers little or no survival benefit over medical treatment. Women are at least as likely as men to be referred for bypass surgery among more symptomatic and more severely diseased patients, in whom surgery offers the greatest survival benefits. These trends were most prominent in the recent years of the study. Based on surgical survival benefits, these referral patterns may represent more appropriate treatment referral for women than men.

Coronary Artery Bypass↗
PubMed1992

beta-Glycerophosphate-induced mineralization of osteoid does not alter expression of extracellular matrix components in fetal rat calvarial cell cultures.

When fetal rat calvarial cells are cultured in medium containing vitamin C, osteoid nodules develop after approximately 15 days of culture. Upon addition of an organic phosphate (beta-glycerophosphate, beta GP), these nodules mineralize. We have now used this system to explore the suggestion made by others that a negative feedback may exist between matrix mineralization on the one hand and the synthesis of alkaline phosphatase and bone matrix collagen on the other by analyzing the synthesis of these proteins and the levels of their mRNAs in mineralizing and nonmineralizing cultures. Our results indicate that in the osteoid nodule-bone nodule system, matrix mineralization did not affect the mRNA levels for osteopontin, type I collagen, bone sialoprotein, or osteocalcin. Synthesis of total protein and collagen and the osteocalcin content of culture media were also not different in the mineralizing and nonmineralizing cultures. However, alkaline phosphatase mRNA was increased in early mineralizing cultures and alkaline phosphatase activity in the cell layer was also increased in mineralizing cultures. Thus, the hypothesis that a direct negative feedback exists between mineralization and matrix protein synthesis is not supported by our experiments.

Alkaline Phosphatase↗
PubMed1992

Incessant automatic ventricular tachycardia complicating acute coxsackie B myocarditis.

A 13-year-old girl presented with incessant ventricular tachycardia complicating acute Coxsackie B3 myocarditis. Electrophysiologic assessment revealed that the tachycardia could not be terminated, overdrive suppressed or accelerated by programmed electrical stimulation, but was transiently slowed by intravenous adenosine triphosphate and had marked spontaneous and sympathoautonomic-mediated fluctuation in the tachycardia cycle length. These features were atypical of reentry and triggered automaticity and suggested that abnormal automaticity was the likely tachycardia mechanism. Intravenous amiodarone slowed the ventricular tachycardia, but the patient eventually succumbed from rapidly progressive left ventricular failure. Postmortem pathohistologic examination confirmed the diagnosis of acute myocarditis.

Adolescent↗
PubMed1992

Identification of patients with coronary disease at high risk for loss of employment. A prospective validation study.

BACKGROUND: Work disability is common in patients with coronary artery disease and adversely affects both economic well-being and quality of life. The purpose of this study was to construct a model to predict premature departure from the work force of patients with coronary disease and to validate this model prospectively in an independent cohort of patients. METHODS AND RESULTS: We enrolled 1,252 coronary disease patients referred for diagnostic cardiac catheterization who were less than age 65, employed, and without prior coronary angioplasty or coronary bypass surgery. Medical, functional, psychological, economic, and job-related variables were measured at the time of baseline diagnostic cardiac catheterization, and all patients were followed for 1 year. Three hundred twelve patients underwent percutaneous transluminal coronary angioplasty (PTCA) within 60 days of catheterization, and 449 had coronary artery bypass graft surgery (CABG) within 60 days of catheterization. The remaining 491 patients were treated with initial medical therapy. Logistic regression was used to develop a multivariable model for predicting 1-year work status in the training sample patients (872 patients enrolled between March 1986 and February 1989). This model was then validated in the independent prospective test sample (380 patients enrolled between March 1989 and June 1990). Eight factors were independent predictors of departure from the work force: lower initial functional status (as assessed by the Duke Activity Status Index), followed by older age, black race, presence of congestive heart failure, lower education level, presence of extracardiac vascular disease, poorer psychological status, and lower job classification. Standard clinical variables provided only 20% of the total predictive information available from the model about follow-up work outcomes, whereas functional measures provided 27%, and demographic and socioeconomic measures provided 45%. In the test sample, the area under the receiver operating characteristic curve for the model predictions was 0.74, compared with 0.80 in the training sample, and model predictions agreed well with observed prevalences of return to work. After adjustment for baseline imbalances, there was no significant difference in 1-year return-to-work rates among the patients receiving initial PTCA or CABG therapy versus initial medical therapy. CONCLUSIONS: Patients with coronary disease who are at high risk for premature departure from the work force can be accurately identified from a combination of medical and nonmedical risk factors. The model developed in this study provides a tool to identify patients at high risk for premature loss from the work force. Such patients may benefit from special multidimensional intervention programs designed to preserve work status. Our data show that revascularization with either PTCA or CABG is not, by itself, sufficient to accomplish this goal.

Angioplasty, Balloon, Coronary↗
PubMed1992

Observational comparison of event-free survival with medical and surgical therapy in patients with coronary artery disease. 20 years of follow-up.

BACKGROUND: The purpose of this study was to describe the long-term event-free survival patterns of patients with significant coronary artery disease treated medically versus patterns of those treated surgically and to evaluate the factors associated with improved event-free survival. METHODS AND RESULTS: We studied the results of 5,824 patients undergoing medical and surgical therapy for ischemic heart disease from 1969 to 1984, with follow-up to 1991. Events considered for this evaluation were nonfatal myocardial infarction or cardiovascular death. The Cox proportional hazards model was used to determine factors differentially affecting surgical event-free survival. The survival benefits previously reported for bypass surgery in this population were largely preserved when event-free survival was examined. The two factors associated with significant event-free survival benefits for surgically treated patients were more severe coronary artery disease and a more recent surgery data. Patients with more severe coronary obstruction had a greater relative improvement with surgery in event-free survival than did patients with less severe anatomic disease. Event-free survival with surgery progressively improved over the period of the study and, by 1984, was significantly better than medical therapy for most patient subgroups. Patients with poor prognosis because of risk factors such as older age, severe angina, or left ventricular dysfunction had a risk reduction with surgery proportional to their overall risk under medical therapy. CONCLUSIONS: Higher-risk patients with more severe disease (due to either coronary disease or other risk factors and age) should be considered for coronary revascularization because it is in these patients that coronary artery bypass graft surgery has the greatest impact in reducing future cardiovascular events.

Cardiac Catheterization↗
PubMed1991

Prognostic value of a treadmill exercise score in outpatients with suspected coronary artery disease.

BACKGROUND: The treadmill exercise test identifies patients with different degrees of risk of death from cardiovascular events. We devised a prognostic score, based on the results of treadmill exercise testing, that accurately predicts outcome among inpatients referred for cardiac catheterization. This study was designed to determine whether this score could also accurately predict prognosis in unselected outpatients. METHODS: We prospectively studied 613 consecutive outpatients with suspected coronary disease who were referred for exercise testing between 1983 and 1985. Follow-up was 98 percent complete at four years. The treadmill score was calculated as follows: duration of exercise in minutes--(5 x the maximal ST-segment deviation during or after exercise, in millimeters)--(4 x the treadmill angina index). The numerical treadmill angina index was 0 for no angina, 1 for nonlimiting angina, and 2 for exercise-limiting angina. Treadmill scores ranged from -25 (indicating the highest risk) to +15 (indicating the lowest risk). RESULTS: Predicted outcomes for the outpatients, based on their treadmill scores, agreed closely with the observed outcomes. The score accurately separated patients who subsequently died from those who lived for four years (area under the receiver-operating-characteristic curve = 0.849). The treadmill score was a better discriminator than the clinical data and was even more useful for outpatients than it had been for inpatients. Approximately two thirds of the outpatients had treadmill scores indicating low risk (greater than or equal to +5), reflecting longer exercise times and little or no ST-segment deviation, and their four-year survival rate was 99 percent (average annual mortality rate, 0.25 percent). Four percent of the outpatients had scores indicating high risk (less than -10), reflecting shorter exercise times and more severe ST-segment deviation; their four-year survival rate was 79 percent (average annual mortality rate, 5 percent). CONCLUSIONS: The treadmill score is a useful and valid tool that can help clinicians determine prognosis and decide whether to refer outpatients with suspected coronary disease for cardiac catheterization. In this study, it was a better predictor of outcome than the clinical assessment.

Adult↗
PubMed1991

Prediction of death and myocardial infarction by radionuclide angiocardiography in patients with suspected coronary artery disease.

The prognostic value of radionuclide angiocardiography was examined in patients with suspected coronary artery disease. Nine hundred and eight patients who underwent rest and exercise radionuclide angiocardiography without subsequent cardiac catheterization were followed for a median of 4.6 years. Fifty-two cardiovascular deaths and 28 nonfatal myocardial infarctions occurred during the follow-up period. Thirty-nine radionuclide angiocardiographic and clinical variables were analyzed in association with the end points of cardiovascular death, total cardiac events and death from all causes using the Cox proportional hazards model and Kaplan-Meier survival estimates. Univariable analysis identified the exercise ejection fraction as the best predictor of cardiovascular death (chi-square = 82), total cardiac events (chi-square = 84) and death from all causes (chi-square = 66). A small subset of patients (n = 45) with an exercise ejection fraction less than 0.35 were at high risk for future cardiac events, whereas most patients (n = 776) had an exercise ejection fraction greater than or equal to 0.50 and a low probability of a subsequent event. Three variables--the exercise ejection fraction, the exercise change in heart rate, and gender--contained independent prognostic information determined by multivariable analysis. The exercise ejection fraction was the strongest independent predictor (p less than 0.0001) for every end point. The measurement of ventricular function during exercise provides important independent prognostic information in patients with suspected coronary artery disease. Radionuclide angiocardiography successfully identifies patients requiring invasive assessment, and the low probability of cardiac events in patients with good exercise ventricular function obviates the need for interventional therapy.

Adult↗
PubMed1991

Complete atrioventricular block complicating inferior wall acute myocardial infarction treated with reperfusion therapy. TAMI Study Group.

Previous studies report larger myocardial infarcts and increased in-hospital mortality rates in patients with inferior wall acute myocardial infarction (AMI) and complete atrioventricular block (AV), but the clinical implications of these complications in patients treated with reperfusion therapy have not been addressed. The clinical course of 373 patients--50 (13%) of whom developed complete AV block--admitted with inferior wall AMI and given thrombolytic therapy within 6 hours of symptom onset was studied. Acute patency rates of the infarct artery after thrombolytic therapy were similar in patients with or without AV block. Ventricular function measured at baseline and before discharge in patients with complete AV block showed a decrement in median ejection fraction (-3.5 vs -0.4%, p = 0.03) and in median regional wall motion (-0.14 vs +0.24 standard deviations/chord, p = 0.05). The reocclusion rate was higher in patients with complete AV block (29 vs 16%, p = 0.03). Patients with complete AV block had more episodes of ventricular fibrillation or tachycardia (36 vs 14%, p less than 0.001), sustained hypotension (36 vs 10%, p less than 0.001), pulmonary edema (12 vs 4%, p = 0.02) and a higher in-hospital mortality rate (20 vs 4%, p less than 0.001), although the mortality rate after hospital discharge was identical (2%) in the 2 groups. Multivariable logistic regression analysis revealed that complete AV block was a strong independent predictor of in-hospital mortality (p = 0.0006). Thus, despite initial successful reperfusion, patients with inferior wall AMI and complete AV block have higher rates of in-hospital complications and mortality.

Aged↗
PubMed1991

Methods for the analysis and assessment of clinical databases: the clinician's perspective.

Innovative approaches to analysing clinical databases can be considered from a perspective of innovations that improve the analytical approach or from a more global perspective in which clinical databases themselves are evaluated as a technology. The analytic approach for using a database to estimate risk can be considered as a matrix of three methodologic concerns: the predictive method; the assessment of the quality of the predictions; and the assessment of the validity or generalizability of the predictions. Considering databases as a technology places in perspective the merit of clinical databases and defines their potential value to the health care system. An awareness of both the clinical and analytic problem encourages innovation and can lead to creative solutions to the many problems present in the analysis of clinical databases.

Clinical Medicine↗
PubMed1991

Effect of extended depot fluphenazine treatment and withdrawal on social and other behaviors of Cebus apella monkeys.

To examine whether or not prolonged exposure to a depot neuroleptic has either residual or "tardive pathological" effects on normal behavior, 38 Cebus apella monkeys were observed daily for 108 weeks. The issue of stress influencing such effects was also addressed. During weeks 25-48 half of the monkeys received 0.22 mg/kg fluphenazine decanoate, IM, every 3 weeks, with the dose increased to 0.33 mg/kg during weeks 49-72. Behavioral measures were combined to form composite behavioral variables which quantify four major aspects of behavior: self- and environment-directed behavior, affiliation, aggression, and normal locomotor activity. Mean plasma fluphenazine levels at 48 h post-injection were 0.13 (+/- 0.03) ng/ml for injections 3-8 and 0.24 (+/- 0.07) ng/ml for injections 11-16. The pre-study null hypothesis that the four major aspects of behavior would not be adversely affected by this treatment during the drug-discontinuation phase of the study (weeks 73-108) was not statistically negated. There were highly significant decreases in self- and environment-directed behaviors and affiliation during the treatment periods, implying that treatment may contribute to the negative symptoms of treated schizophrenics. Stress reduced the above effects. Aggression showed some increase during early drug discontinuation, accentuated by stress. Recovery of normal (baseline) behavioral scores began by week 7 after the last treatment. Mild (bucco-lingual) tardive dyskinesias persisted in 30% of the animals for a prolonged time.

Animals↗
PubMed1991

Using ordinal logistic regression to estimate the likelihood of colorectal neoplasia.

The utility of ordinal logistic regression in the prediction of colorectal neoplasia was demonstrated in a group of 461 consecutive patients undergoing colonoscopy in a community practice. One hundred twenty-nine patients had adenomatous polyps and 34 had colorectal adenocarcinoma. An ordinal logistic regression model developed in a random subset (292 patients) identified five predictors of colorectal neoplasia. Colorectal neoplasia risk could be predicted using the patient's age, sex, hematocrit, fecal occult blood test result and indication for colonoscopy. The risk of colorectal neoplasia in the remaining subset of patients (169) could be reliably estimated from the model. Ordinal logistic regression analysis in this select group of patients can accurately estimate the likelihood of colorectal neoplasia. Because the generalizability of our findings are unknown, the model should not be applied to other patients. However, application of this technique to an unselected group of patients not already referred for colonoscopy could provide unbiased estimates of colorectal neoplasia risk in individual patients.

Adenocarcinoma↗
PubMed1991

Dynamics of behavioral thermoregulation in the rat.

Past studies have found that the laboratory rat placed in a temperature gradient prefers temperatures that are markedly below its lower critical ambient temperature (LCT), whereas other rodents (e.g., mouse, hamster, and guinea pig) generally select thermal environments associated with minimal metabolic expenditure. To further study the rat's thermoregulatory behavior, a temperature gradient was designed to monitor the selected ambient temperature (STa) and motor activity (MA) of food-deprived rats of the Long-Evans (LE), Fischer 344 (F344), and Sprague-Dawley (SD) strains over a 22-h period. All three rat strains selected relatively cool STas of 21-26 degrees C during the first 1-3 h in the temperature gradient. This was followed by a gradual increase in the STa that peaked at 4 (F344) to 6 h (SD and LE) after being placed in the gradient. The LE strain had a significantly lower STa during the initial period in the gradient. There were slight decreases in the STa during the nocturnal phase in the F344 and SD strains concomitant with marked increases in MA. These results indicate that the rat requires a relatively long adjustment period in a temperature gradient before it exhibits STas that are associated with minimal metabolic expenditure. Given adequate time for accommodation, behavioral thermoregulatory responses of the rat appear to be similar to those of other rodents.

Analysis of Variance↗