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T L Mitchell

Publications and source records attributed to T L Mitchell.

18 recordsLinked to original sources
PubMed2001

Age- and sex-based nomograms from coronary artery calcium scores as determined by electron beam computed tomography.

We present data for 18,785 patients undergoing electron beam computed tomography, dividing them by sex and age (using 5-year age increments) to determine coronary artery calcium scores representing the 50th and 75th percentiles for each group. Because risk stratification is an integral part of determining therapies for coronary artery disease, age- and sex-based scores may be more clinically useful than total coronary artery calcium scores alone.

Adult↗
PubMed2001

Mouse eosinophil-associated ribonucleases: a unique subfamily expressed during hematopoiesis.

A unique family of ribonucleases was identified by exhaustive screening of genomic and cDNA libraries using a probe derived from a gene encoding a ribonuclease stored in the mouse eosinophil secondary granule. This family contains at least 13 genes, which encode ribonucleases, and two potential pseudogenes. The conserved sequence identity among these genes (approximately 70%), as well as the isolation/purification of these ribonucleases from eosinophil secondary granules, has led us to conclude that these genes form a unique clade in the mouse that we have identified as the Ear (Eosinophil-associated ribonuclease) gene family. Analyses of the nucleotide substitutions that have occurred among these ribonuclease genes reveal that duplication events within this family have been episodic, occurring within three unique periods during the past 18 x 10(6) years. Moreover, comparisons of non-synonymous (K(a)) vs. synonymous (K(s)) rates of nucleotide substitution show that although these genes conserve residues necessary for RNase activity, selective evolutionary pressure(s) exist such that acquired amino acid changes appear to be advantageous. The selective advantage of these amino acid changes is currently unclear, but the occurrence of this phenomenon in both the mouse and the human highlights the importance of these changes for Ear and, therefore, eosinophil effector function(s).

Amino Acid Sequence↗
PubMed2000

Maximal exercise test as a predictor of risk for mortality from coronary heart disease in asymptomatic men.

Exercise testing in asymptomatic persons has been criticized for failing to accurately predict those at risk for coronary heart disease (CHD). Previous studies on asymptomatic subjects, however, may not have been large enough or long enough to provide reliable outcome measures. This study examines the ability of a maximal exercise test to predict death from CHD and death from any cause in a population of asymptomatic men. This is a prospective longitudinal study performed between 1970 and 1989, with an average follow-up of 8.4 years. The subjects are 25,927 healthy men, 20 to 82 years of age at baseline (mean 42.9 years) who were free of cardiovascular disease and who were evaluated in a preventive medicine clinic. The main outcome measures are CHD mortality and all-cause mortality. During follow-up there were 612 deaths from all causes and 158 deaths from CHD. The sensitivity of an abnormal exercise test to predict coronary death was 61%. The age-adjusted relative risk of an abnormal exercise test for CHD death was 21 (6.9 to 63.3) in those with no risk factors, 27 (10.7 to 68.8) in those with 1 risk factor, 54 (21.5 to 133.7) in those with 2 risk factors, and 80 (30.0 to 212. 5) in those with >/=3 factors. A maximal exercise test performed in asymptomatic men free of cardiovascular disease does appear to be a worthwhile tool in predicting future risk of CHD death. An abnormal exercise test is a more powerful predictor of risk in those with than without conventional risk factors.

Adult↗
PubMed2000

Low fasting plasma glucose level as a predictor of cardiovascular disease and all-cause mortality.

BACKGROUND: Although medical textbooks usually classify fasting plasma glucose <70 or 80 mg/dL (<3.89 or 4.44 mmol/L) as abnormal, the prognosis for patients with low fasting plasma glucose is unclear. METHODS AND RESULTS: We conducted prospective cohort studies among 40 069 men and women to investigate the association between fasting plasma glucose levels and cardiovascular disease and all-cause mortality. We documented a U-shaped relation between fasting plasma glucose and mortality. In addition to diabetes and impaired fasting glucose levels, low fasting plasma glucose levels were also associated with high mortality. After multivariate adjustment for age, sex, study population, ethnicity, current smoking status, high blood pressure, total cholesterol, body mass index, triglycerides, history of cardiovascular disease and cancer, and a family history of cardiovascular disease, patients with fasting plasma glucose <70 mg/dL (<3.89 mmol/L) had a 3.3-fold increased risk of cardiovascular disease mortality, and patients with fasting plasma glucose 70 to 79 mg/dL (3.89 to 4.43 mmol/L) had a 2.4-fold increased risk compared with the risk in patients with fasting plasma glucose 80 to 109 mg/dL (4.44 to 6.05 mmol/L) (tests for trend P<0.0001). Participants with low fasting plasma glucose levels also had increased risk of all-cause mortality (test for trend P<0.0001). CONCLUSIONS: Participants with low fasting plasma glucose levels had a high risk of cardiovascular disease and all-cause mortality.

Adult↗
PubMed2000

Alcohol intake and incidence of type 2 diabetes in men.

OBJECTIVE: To evaluate the relation between alcohol intake and incidence of type 2 diabetes. RESEARCH DESIGN AND METHODS: This prospective study included 8,663 men with fasting plasma glucose measurements from at least two medical examinations. Alcohol intake was classified into five groups: nondrinkers and four quartiles (Qs) of drinkers according to the amount of alcohol intake. Type 2 diabetes was diagnosed by 1997 American Diabetes Association criteria. RESULTS: There were 149 incident cases of type 2 diabetes during 52,588 person-years of follow-up. There was a U-shaped association between alcohol intake and diabetes, with the lowest incidence of diabetes at Q2 (61.9-122.7 g/week). As compared with Q2, men in Q3 and Q4 had a 2.2- (95% CI 1.2-3.9, P = 0.01) and 2.4-fold (1.4-4.4, P<0.01) risk of developing diabetes, while nondrinkers and men in Q1 had 1.8- (1.0-3.3, P<0.05) and 1.4-fold (0.7-2.6, P = 0.34) higher risk of diabetes, respectively. These associations persisted after adjustment for age, fasting plasma glucose, smoking, BMI, blood pressure, serum triglyceride concentration, cardiorespiratory fitness, HDL cholesterol, waist circumference, and parental diabetes. CONCLUSIONS: We observed an elevated risk of developing type 2 diabetes in nondrinkers and men with high alcohol intakes, when compared with men who reported moderate alcohol intake. Men with a high alcohol intake may be able to reduce their risk of developing type 2 diabetes if they drink less.

Adult↗
PubMed1999

The association between cardiorespiratory fitness and impaired fasting glucose and type 2 diabetes mellitus in men.

BACKGROUND: Several studies show an inverse association between self-reported physical activity and type 2 diabetes. It is not known whether physical activity or cardiorespiratory fitness is associated with the onset of objectively determined impaired fasting glucose and type 2 diabetes. OBJECTIVE: To determine whether cardiorespiratory fitness, an objective marker of physical activity, is associated with risk for impaired fasting glucose and type 2 diabetes. DESIGN: Population-based prospective study. SETTING: Preventive medicine clinic. PATIENTS: 8633 nondiabetic men (of whom 7511 did not have impaired fasting glucose) who were examined at least twice. MEASUREMENTS: Cardiorespiratory fitness (determined by a maximal exercise test on a treadmill), fasting plasma glucose level, and other clinical and personal characteristics and incidence of impaired fasting glucose and type 2 diabetes. RESULTS: During an average follow-up of 6 years, 149 patients developed type 2 diabetes and 593 patients developed impaired fasting glucose. After age, cigarette smoking, alcohol consumption, and parental diabetes were considered, men in the low-fitness group (the least fit 20% of the cohort) at baseline had a 1.9-fold risk (95% CI, 1.5- to 2.4-fold) for impaired fasting glucose and a 3.7-fold risk (CI, 2.4- to 5.8-fold) for diabetes compared with those in the high-fitness group (the most fit 40% of the cohort). The risk for impaired fasting glucose was elevated in older men and those with a higher body mass index. Age, body mass index, blood pressure, triglyceride level, and a history of parental diabetes were also directly related to risk for type 2 diabetes. CONCLUSIONS: Low cardiorespiratory fitness was associated with increased risk for impaired fasting glucose and type 2 diabetes. A sedentary lifestyle may contribute to the progression from normal fasting glucose to impaired fasting glucose and diabetes. Risk for type 2 diabetes was elevated in older persons and those with higher body mass index, blood pressure, and triglyceride levels and a parental history of diabetes.

Adult↗
PubMed1996

High-performance capillary electrophoresis-pure creatine monohydrate reduces blood lipids in men and women.

1. A randomized, double-blind, placebo-controlled trial utilizing creatine as a potential lipid-lowering agent was conducted to determine plasma lipid, lipoprotein, glucose, urea nitrogen and creatinine profiles in men and women ranging in age from 32 to 70 years. 2. Thirty-four subjects (18 men and 16 women) with total cholesterol concentrations exceeding 200 mg/dl received either a creatine supplement (5 g of creatine plus 1 g of glucose) or a glucose placebo (6 g of glucose) for 56 days. Creatine and placebo were taken orally four times a day for 5 days and then twice a day for 51 days. Plasma analyses were measured at baseline, 4 and 8 weeks of treatment, and at 4 weeks after cessation of treatment (week 12). 3. Significant reductions in plasma total cholesterol, triacylglycerols and very-low-density lipoprotein-C occurred within the creatine monohydrate group. Minor reductions in plasma total cholesterol from baseline (233 +/- 9 mg/dl) of 6% and 5% occurred at weeks 4 and 8, respectively, before returning to baseline at week 12. Baseline triacylglycerols (194 +/- 21 mg/dl) and very-low-density lipoprotein-C (39 +/- 4 mg/dl) were reduced by 23% and 22% at weeks 4 and 8, respectively, and remained attenuated by 26% at week 12. These results remained consistent when data were separated and analysed by gender. Finally, a small, but statistically significant increase in urea nitrogen was observed in women between baseline (11.8 +/- 0.7 mg/dl) and week 8 (13.8 +/- 0.7 mg/dl, P < 0.05). No significant differences were noted for low-density lipoprotein-C, high-density lipoprotein-C, total cholesterol/high-density lipoprotein ratio, glucose, creatinine, body mass, body mass index or physical activity within or between the experimental and placebo groups. However, a trend towards reduced blood glucose levels was present in males given creatine monohydrate (P = 0.051). 4. These preliminary data suggest that creatine monohydrate may modulate lipid metabolism in certain individuals. These observations may demonstrate practical efficacy to the hyperlipidaemic patient as well as providing possible new mechanistic insights into the cellular regulation of blood lipid concentrations.

Adult↗
PubMed1996

Rethinking research relationships in qualitative research.

The research relationship within qualitative research methods, that is, the relationship between researcher and research participant, is reexamined in this paper. We draw upon our own research experiences of working with high-risk individuals and vulnerable communities in reframing a discussion of the interview process. We illustrate the emotionally provocative and volatile nature of the research relationship and argue for the necessity of social research protocols which extend beyond a utilitarian research framework, the expansion of the researcher's role to include skillful navigation of the intersubjective aspects of research interviewing, and participant advocacy.

Humans↗
PubMed1994

The safety of exercise testing.

Although exercise testing is a safe activity for the vast majority of individuals being tested, complications during or soon after testing do occur, and safety is an extremely important consideration. In reviewing published rates of complications, it appears that complication rates around 5 per 10,000 tests and death rates around 0.5 per 10,000 tests might be expected. The rate of complications and deaths in our clinic is much lower than these published rates, but our population is, in general, a healthier population than those reported on in other studies. It is instructive to review the details of exercise tests in which complications have occurred, although sometimes it is impossible to predict that an untoward occurrence is imminent. Exercise testing soon after myocardial infarction or angioplasty can generally be conducted safely by knowledgeable professionals, although submaximal testing is recommended under these circumstances. Following accepted contraindications to testing and accepted indications for terminating an exercise test is still very important to ensure the safety of testing. If one desires to step outside these recognized guidelines, the anticipated benefits of testing must clearly outweigh the inherent risks. Any testing facility must have appropriate safety equipment, including a defibrillator, and personnel must be regularly drilled in responding to emergencies. In reviewing our experience at the Cooper Clinic, practical suggestions have been offered that should make exercise testing, which is already a very safe activity, even safer.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Yield of the screening review of systems: a study on a general medical service.

STUDY OBJECTIVE: To determine the usefulness of screening reviews of the cardiopulmonary and gastrointestinal systems during medical admissions. DESIGN: Case series. SETTING: General internal medicine ward of a university hospital. PATIENTS: 550 consecutive medical patients were initially screened at admission. The authors excluded 265 patients with life-limiting medical conditions, and they studied 98 patients with no known cardiopulmonary disease and 207 patients with no known gastrointestinal disease. INTERVENTIONS: Positive responses to screening systems review questions were evaluated using a standardized testing algorithm. MAIN OUTCOME MEASURES: Numbers of new diagnoses; potential for patient benefit. MAIN RESULTS: The authors made 26 new diagnoses for 25 patients (95% confidence limits, 16 to 37 patients), two of whom may have gained years of life as a result. CONCLUSIONS: The absolute yield of the screening cardiopulmonary and gastrointestinal reviews of systems of 550 patients admitted to an internal medicine service of a university hospital was a new diagnosis in about 5% of patients. An estimate of the cost-effectiveness compares favorably with those of other accepted screening practices.

Adult↗
PubMedDate not supplied

Incidental detection of preclinical renal tumors with electron beam computed tomography: report of 26 consecutive operated patients.

PURPOSE: The purpose of this work was to describe the positive predictive value of electron beam CT (EBCT) for diagnosis of solid renal tumors. METHOD: Among 11,932 consecutive patients undergoing screening EBCT, 27 cases met EBCT criteria for solid renal tumors. Twenty-six of 27 patients underwent surgery. RESULTS: Surgical pathology identified 25 solid renal tumors and 1 adrenal hemorrhage with thrombus. Twenty tumors were classified as T1N0M0, one was T2N0M0, and one was T3aN0M0. All tumor patients are clinically well at 1-41 months (mean 17 months) postoperatively. None of the patients had clinical signs or symptoms characteristic of renal malignancy. CONCLUSION: EBCT is an effective tool for detection of solid renal tumors in a healthy outpatient population (positive predictive value 0.96). The detection rate is low [0.2% (26/11,932) at our facility] in patients undergoing EBCT for other indications. The cost-effectiveness and sensitivity of this technique for solid renal tumor detection among various populations remain to be determined.

Adenoma, Oxyphilic↗