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Biomedical subjects

R E Gleason

Publications and source records attributed to R E Gleason.

At least 37 records · Page 2Linked to original sources
PubMed1994

The 24-h pattern and rate of leucine oxidation, with particular reference to tracer estimates of leucine requirements in healthy adults.

Daily leucine oxidation and derived values for whole-body leucine balance, obtained by continuous measurement throughout a 24-h period, were compared with those predicted from short-term measurements during fasted and fed states in five healthy adults studied during two 6-d experimental diet periods, each immediately followed by a 24-h continuous intravenous tracer infusion of L-[1-13C]leucine. Leucine intake was either 14 or 38.3 mg.kg-1.d-1. Mean measured daily leucine oxidation (mg leucine.kg-1.d-1) was 27.8 and 45.2 for the 14- and 38.3-mg intakes, respectively. Oxidation rates predicted by extrapolation of rates measured during the final hour of fasting (15 h after last meal) and the 5th h of feeding were approximately 12% higher (P < 0.01) than measured rates for both diets. For the prediction based on the 12th h of fasting and 5th h of feeding, it was 4% higher or 0.4% lower than measured rates for the 38.3- and 14- mg intakes, respectively. Hence, relatively small differences exist between measured vs predicted estimates of daily leucine oxidation and balance. These studies support previous conclusions that the current, international requirement value for leucine in healthy adults is far too low.

Adult↗
PubMed1994

Similar 24-h pattern and rate of carbon dioxide production, by indirect calorimetry vs. stable isotope dilution, in healthy adults under standardized metabolic conditions.

We investigated the applicability of the bicarbonate stable isotope dilution technique for accurate determination of 24-h energy expenditure in humans and in reference to the conduct of short-term (< or = 8 h) metabolic studies. Five healthy adult subjects consumed for 4 d a standard diet providing approximately 188 kJ.kg-1.d-1 and 1.0 g.kg-1.d-1 of egg protein. From d 4 at 1800 h to d 5 at 1800 h, a 24-h metabolic study, combining indirect calorimetry with an intravenous infusion of 13C-labeled sodium bicarbonate, was performed under standardized conditions of 12 h fasting-12 h feeding. "Measured" CO2 production (VCO2) (indirect calorimetry) over 24 h was not significantly different from "predicted" VCO2 (bicarbonate dilution) (218.31 +/- 20.91 vs. 221.51 +/- 19.44 mmol CO2.kg-1.d-1, respectively) (P = 0.34). Further, 24-h VCO2 and energy expenditure were determined by extrapolating from "predicted" VCO2 during the last hour of fasting (15th hour following last meal) and the fifth hour of the small hourly meal-feeding phase. The maximum difference for an individual subject between the above-calculated 24-h energy expenditure and that from 24-h indirect calorimetry measurements was < 4%. These results support use of the present experimental protocol, and the bicarbonate dilution technique, lasting < or = 8 h, to obtain reliable quantitative estimates of 24-h CO2 production and energy expenditure in healthy adult humans.

Adult↗
PubMed1994

Regulation of aldosterone secretion in hypertensive blacks.

Hypertension in blacks is common, often severe, and largely unexplained. Recent studies have suggested that aldosterone secretion in blacks may be reduced, whereas older data demonstrate no racial differences in aldosterone excretion. We performed this study to examine adrenal responsiveness in black hypertensive patients under controlled metabolic conditions. Thirty-one black hypertensive patients and 7 black normotensive subjects were studied on intakes of 10 mmol/d sodium and 100 mmol/d potassium, with the renin-angiotensin-aldosterone system further stimulated by upright posture or infusion of angiotensin II (Ang II). Forty-six hypertensive and 14 normotensive whites underwent the same protocol as a comparison group. Hypertensive blacks and whites had similar mean basal plasma aldosterone levels on a low salt diet, lower in both groups than in normotensive subjects. In the black patients, however, plasma aldosterone responses were significantly lower than responses in white hypertensive patients when further stimulated by either posture (1451 +/- 216 versus 2571 +/- 225 pmol/L [52.3 +/- 7.8 versus 92.7 +/- 8.1 ng/dL], P < .002) or Ang II infusion (843 +/- 122 versus 1617 +/- 189 pmol/L [30.4 +/- 4.4 versus 58.3 +/- 6.8 ng/dL], P < .001). Renin status did not account for the difference. Basal and stimulated plasma aldosterone concentrations, on the other hand, were similar in normotensive white and black subjects. Blunted adrenal responses to upright posture and Ang II infusion are common among black hypertensive patients. These abnormalities may be part of a larger constellation of abnormalities in blacks, reflecting perhaps a greater, more frequent underlying disturbance in salt handling than in whites.

Adrenocorticotropic Hormone↗
PubMed1993

Effect of pharmacological daytime doses of melatonin on human mood and performance.

Melatonin (10, 20, 40, or 80 mg, PO) or placebo was administered at 1145 hours on five separate occasions to 20 healthy male volunteers and the effects on serum melatonin levels, mood, performance, and oral temperature were monitored. Subjects were studied between 0930 and 1700 hours. A battery of interactive computer tasks designed to assess performance and mood was completed, oral temperature was measured, and blood samples were taken for serum melatonin radioimmunoassay. The areas under the time-melatonin concentration curve (AUC) varied significantly in proportion to the various melatonin doses. Compared with placebo treatment, all melatonin doses significantly decreased oral temperature, number of correct responses in auditory vigilance, response latency in reaction time, and self-reported vigor. Melatonin also increased self-reported fatigue, confusion, and sleepiness.

Adult↗
PubMed1993

Preliminary screening of the relationship of serum lipids to survival of chronic dialysis patients.

To assess the predictive value of serum lipid measurements in dialysis patients once the initial decrease on early dialysis had occurred, we obtained random serum cholesterol and triglyceride levels in stable, chronic dialysis patients who were then followed up to 9 years. Derived LDL (DLDL) was estimated by the Friedewald formula, calculated for all HDL levels between 30 and 45 mg/dL, and evaluated statistically against a panel of vascular disease markers, including clinical assessment for coronary, peripheral, and cerebrovascular disease; ECG, both standard and ambulatory; two-dimensional echocardiogram; and medications. Survival was calculated from entry (not dialysis onset) for 58 hemodialysis and 33 peritoneal dialysis patients. The 91 patients (49 males, 74 diabetics) were divided by cholesterol level (> or = 175 mg/dL = 53, < 175 = 38), triglyceride (> or = 175 mg/dL = 55, < 175 = 36), and DLDL (> or = 75 = 58, < 75 = 24). High total cholesterol was present in a larger proportion of females than low cholesterol, but groups were not different with respect to all vascular determinants, including survival (mean = 33.4 months vs. 43.2, p = NS). High vs. low triglyceride groups were not different with respect to vascular indicators, except for both incidence of abnormal standard ECG (69% vs. 42%, p < 0.05) and survivals (mean = 42.0 vs. 30.7, p < 0.05; 1 year = 80% vs. 56%, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Screening for lung cancer re-examined. A reinterpretation of the Mayo Lung Project randomized trial on lung cancer screening.

In the 1970s, three randomized trials, each involving approximately 10,000 male subjects, were carried out to determine the value of lung cancer screening in cigarette smokers. These studies have been widely interpreted as providing strong evidence that screening does not contribute to decreased death rates, and, accordingly, the American Cancer Society firmly recommends against lung cancer screening. No randomized trial, however, has evaluated screening for lung cancer in women, who currently comprise 39% of the lung cancer population. The trials performed at Memorial-Sloan Kettering and at Johns Hopkins were designed so that subjects were randomized to either a single screen (annual chest x-ray alone) or a dual screen (annual chest x-ray and every-4-month sputum cytology) group. While the results of both revealed no difference in mortality between the groups, these studies were designed to examine the value of sputum cytology, and no conclusion regarding the efficacy of chest x-rays can be inferred. In the Mayo Lung Project, patients were randomized to a screened group in which a chest x-ray and sputum cytology were obtained every 4 months or to a control group in which an annual chest x-ray and cytology were simply recommended. The results indicate that after 6 years, more lung cancers were detected among the 4,618 men in the screened group (206 cases, 4.46%) than in the 4,593 men in the control group (160 cases, 3.48%). The screened group showed a superiority over the control subjects in resectability rate (46% vs 32%) and 5-year survival (33% vs 15%). However, the number of cancer deaths was slightly greater in the screened (122) than in the control group (115), and, consequently, the mortality rates were not significantly different among the groups. An "overdiagnosis bias" has been suggested to account for the increased number of lung cancers detected in the screened vs the control population in the Mayo Lung Project. This explanation is statistically plausible, but, given the status of lung cancer as the most lethal of malignancies, is biologically unlikely. An alternative hypothesis is that chance alone might have accounted for the observed 0.98% difference in lung cancer detection rates. Were this the case, then 46 additional cases would have been detected in the control group had this chance event not occurred.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

The concentrations of collagen-associated amino acids are higher in GnRH agonist-treated uterine myomas.

OBJECTIVE: To test the hypothesis that the effects of estrogen reduction on uterine leiomyoma regression are mediated through changes in cell density or the extracellular matrix. METHODS: Uterine myomas were obtained from 20 women who had received randomly either the GnRH agonist leuprolide acetate depot for 3 months or placebo. The biochemical and morphologic characteristics studied included: total protein, DNA, and amino acid concentrations; histologic appearance; collagen content; and nuclear density. RESULTS: The absolute and relative concentrations of hydroxylysine, hydroxyproline, glycine, and proline were significantly greater (P < .05) in uterine myomas from patients pretreated with a GnRH agonist compared with placebo-treated controls. The GnRH agonist was also associated with trends toward increased mean total protein, DNA, and nuclear density, but the differences did not reach statistical significance. CONCLUSIONS: The concentrations of the amino acids contained in collagen were significantly greater in uterine myomas from patients treated with the GnRH agonist compared to myomas from placebo-treated controls. In addition, our observations suggest that the reduction in uterine myoma volume associated with GnRH agonist therapy is associated with alterations in the extracellular matrix.

Amino Acids↗
PubMed1993

The effect of operative technique and uterine size on blood loss during myomectomy: a prospective randomized study.

OBJECTIVES: To compare operative blood loss between two accepted blood loss-reducing techniques used during myomectomy and to evaluate the effect of preoperatively determined uterine volume on blood loss. DESIGN: Subjects were stratified by ultrasound-determined uterine volume < 600 cm3 (n = 11) and > or = 600 cm3 (n = 10) and then randomized into treatment groups. The same radiologist, surgeons, and anesthetic induction technique were involved in every case. In the pharmacologic technique, diluted vasopressin (20 U in 20 mL normal saline) was injected into the serosa and/or myometrium overlying the fibroid(s) before the uterine incision(s). In the mechanical technique, a penrose drain tourniquet was passed through defects created in the broad ligaments at the level of the internal os and secured posteriorly, occluding the uterine vessels. In addition, vascular clamps were placed on the infundibulopelvic ligaments, occluding anastomotic blood flow through the ovarian vessels. RESULTS: There was no difference in operative blood loss, operating time, preoperative and intraoperative mean arterial blood pressures, postoperative febrile morbidity, preoperative and postoperative hematocrits, transfusion rates, and length of hospital stay between groups. Blood loss was significantly greater for uteri with ultrasound-determined volumes > or 600 cm3 (627 +/- 175 mL, mean +/- SEM) than for those < 600 cm3 (228 +/- 49 mL). For all subjects, blood lost while operating on the uterus (mean, 379 mL; range, 35 to 1,968 mL) was positively correlated with the total weight of the fibroids resected and with time spent operating on the uterus. Total blood loss (mean, 418 mL; range, 42 to 1,968 mL) was also positively correlated with the time spent operating on the uterus and with total operating time. CONCLUSIONS: There were no demonstrable differences in blood loss, morbidity, or transfusion requirements between subjects undergoing myomectomy using pharmacologic vasoconstriction and mechanical vascular occlusion techniques. Blood loss during myomectomy is primarily incurred while operating on the uterus and is correlated with preoperative uterine size, total weight of fibroids removed, and operating time.

Adult↗
PubMed1993

The reproducibility of the revised American Fertility Society classification of endometriosis.

OBJECTIVE: To assess the degree of intraobserver and interobserver variability in endometriosis staging using the revised American Fertility Society (AFS) classification of endometriosis. DESIGN: Videotapes of laparoscopies of 20 patients with endometriosis were each scored twice by five observers. SETTING: The reproductive endocrine unit of a tertiary care, university-affiliated hospital. SUBJECTS: Five subspecialty-certified reproductive endocrinologists. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Variability in assigned score was measured for each of the five components of the AFS classification, as well as total scores and stage of endometriosis. RESULTS: There was considerable variability in the scores assigned to each videotape, both by the same observer and by different observers. The grand total score, which ranged from 0 to 90, varied with an SD of 13.44 when a single patient was rated twice by the same observer and varied with an SD of 17.12 when a single patient was rated by two different observers. Among individual components of the score, the greatest variability occurred in endometriosis of the ovary and cul-de-sac obliteration, with less variability observed for peritoneum endometriosis and for ovarian and tubal adhesions. Comparison of intraobserver and interobserver scores resulted in a change in endometriosis stage in 38% and 52% of patients, respectively. There were statistically significant differences in mean endometriosis scores among the observers in four of the five anatomic categories examined. CONCLUSIONS: Intraobserver and interobserver variability was high for ovarian endometriosis and cul-de-sac subscores using the revised AFS classification of endometriosis.

Endometriosis↗
PubMed1992

Usefulness of left ventricular size and function in predicting survival in chronic dialysis patients with diabetes mellitus.

To identify patients at high risk for sudden death, a group of stable patients on maintenance dialysis with diabetes mellitus were studied for up to 135 months to determine if there were clinical, laboratory or echocardiographic predictors of high risk. Eighty-two patients on maintenance dialysis who underwent clinical, laboratory evaluation and echocardiography were enrolled and followed for a mean of 25 months for cardiac and noncardiac complications. Thirty-seven patients with normal wall motion and left ventricular (LV) internal diameter had a mean survival of 35.8 months; 28 patients survived greater than 12 months. Seven patients with normal LV wall motion and dilated LV cavities had a mean survival of 45.7 months; 7 patients survived greater than 12 months. Fifteen patients with abnormal LV wall motion and normal internal LV dimensions had a mean survival of 17 months; 7 patients survived greater than 12 months. Twenty-three patients with both abnormal LV wall motion and dilated LV cavities had a mean survival of 7.8 months; 5 patients survived greater than 12 months. Although echocardiographic abnormalities predicted cardiac mortality at 6 and 12 months, the combination of an abnormal standard electrocardiogram at baseline, clinical history of angina pectoris, and prior documented myocardial infarction or congestive heart failure did not. When the study group was divided by mode or duration of dialysis, presence or absence of diabetes, or use of cardioactive drugs, echocardiographic LV wall motion abnormalities remained the most important determinant of survival.

Adult↗
PubMed1992

Preoperative evaluation for diabetic renal transplantation: impact of clinical, laboratory, and echocardiographic parameters on patient and allograft survival.

OBJECTIVE: To assess the impact on renal transplant patients and graft survival of clinical, laboratory, and echocardiographic parameters commonly measured prior to surgery. PATIENTS: Forty-seven consecutive diabetics with preoperative echocardiograms at the time of transplantation. METHODS: Clinical history, standard chest roentgenogram, electrocardiogram, blood tests, echocardiograms, and HLA testing at baseline; follow-up from 2 to 7 years with periodic reassessment of graft function. RESULTS: Patient survival did not appear to be influenced by age, sex, or type of allograft. A history of either myocardial infarction, congestive heart failure, or angina was present in 15 patients with 3-year survival of 50% (72% if not present, p less than 0.05). Histocompatibility testing did not impact on survival. Serum sodium, potassium, calcium, phosphate, and calcium-phosphate product did not discern different survival groups. A hematocrit greater than 30% was present in 15 patients with 3-year survival of 43% (73% if not present, p less than 0.05). Greater than 10% antibody sensitization of the recipient resulted in a 3-year survival of 38% in eight patients (68% if not present, p less than 0.05). Radiologic evidence of cardiomegaly or congestive heart failure and standard electrocardiographic evidence for left ventricular hypertrophy or strain did not impact on survival. Echocardiographic measurements of left ventricular end-diastolic diameter, posterior wall thickness, or ejection fraction were also not predictive. Increased end-systolic diameter (10 patients, 30% 3-year survival versus 69%, p less than 0.05) and decreased velocity of circumferential fiber shortening (11 patients, 45% 3-year survival versus 71%, p less than 0.05) both appeared to be related to survival. Increased accuracy of prediction could be obtained by adding risk factors so that a history of coronary artery disease and increased end-systolic diameter predicted 3-year survival of 42% versus 82% if neither was present. In terms of graft survival, no clinical, radiographic, or electrocardiographic result yielded predictive information. Among the laboratory tests, only highly antibody-sensitized patients (eight patients, 0% 3-year survival versus 66% 3-year survival, p less than 0.001) showed different survival patterns. Echocardiographic elevated end-systolic diameter predicted a significantly (p less than 0.001) decreased graft survival (3-year survival 33% versus 63%). CONCLUSION: Preoperative prediction of patient and graft survival in diabetic renal transplantation may be enhanced by echocardiographic assessment of systolic load and function. For patients with normal systolic function, whose hematocrit is below 30%, with preformed antibodies less than 10%, renal transplantation has an excellent prognosis; invasive cardiac procedures are not likely required. Since these risk factors are likely additive, a high-risk group may be identified. These latter patients should undergo coronary angiography.

Adult↗
PubMed1992

Comparison of frame size and body mass index methods of assessment in the study of blood lipids.

This study compared frame size and body mass index methods of assessment in relation to blood lipid levels. The data were obtained from the records of 84 men and 193 women who voluntarily participated in health fairs held at two suburban hospitals. Significant relationships and differences were found between the anthropometric and lipid variables studied. The two methods of classification denoted moderate association and reflected some divergence in classification between them.

Adult↗
PubMed1992

Menstrual cyclicity of CA-125 in patients with endometriosis.

OBJECTIVE: To examine the serum levels of CA-125 in the menstrual, follicular, and luteal phases of the menstrual cycle in women with endometriosis and to determine if serum CA-125 levels drawn during menses improve the clinical utility of the test in diagnosing endometriosis. DESIGN: Serum CA-125 was measured in the menstrual, follicular, and luteal phases of the cycle preceding surgery. CA-125 levels for each phase were categorized by postoperative diagnosis and endometriosis stage. SETTING: The reproductive endocrine unit of a tertiary care university-affiliated hospital. PATIENTS: A total of 65 patients were recruited from the Fertility and Endocrine Unit and the Gynecology Service of Brigham and Women's Hospital. MAIN OUTCOME MEASURE: Serum CA-125 levels were measured by an immunoradiometric assay and were stratified by menstrual cycle phase, diagnosis, and stage of endometriosis. The menstrual cycle phase was confirmed by serum estradiol and progesterone measurements. RESULTS: Serum CA-125 levels in patients with stages II to IV endometriosis were significantly elevated in the menstrual phase compared with levels drawn in the nonmenstrual follicular and luteal phases. The sensitivity and specificity of CA-125 for the diagnosis of endometriosis were not significantly better in the menstrual than in the follicular or luteal phases. CONCLUSIONS: Despite menstrual cyclicity of CA-125, measurement of serum CA-125 during menses does not improve the clinical utility of the test in the diagnosis of endometriosis.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1992

The effect of consecutive day inseminations on semen characteristics in an intrauterine insemination program.

This study demonstrates a statistically significant decrease in semen volume, sperm concentration, and sperm motility in samples obtained on the 2nd day of consecutive day inseminations in an IUI program. This diminution in semen characteristics persists despite sperm washing. The effects of a second ejaculation on semen parameters in oligospermic and asthenospermic men were mixed. Thus, in general, sperm-washing procedures cannot overcome the natural reduction in semen quality produced by frequent ejaculations. Clinicians may wish to use this information in timing IUI cycle inseminations.

Ejaculation↗
PubMed1991

Plasma amino acid concentrations in healthy elderly men and women.

Postabsorptive plasma concentrations of the large neutral amino acids (LNAAs) were measured in 74 elderly (age 71 +/- 8 y) and 138 young (age 26 +/- 5 y) healthy subjects. Plasma concentrations of valine, leucine, and isoleucine were significantly lower in young females than in young males. This gender-related difference was not observed among elderly subjects because aging was associated with a significant rise in plasma LNAAs in females but not in males. Multiple-regression analysis of plasma amino acid concentrations from female subjects revealed a significant and positive effect of age on plasma valine, leucine, isoleucine, phenylalanine, and tyrosine but not on plasma tryptophan or methionine. Tryptophan was the only amino acid to exhibit a significant response to age in males, consisting of a 14% decline in the elderly subjects. Percentile ranges are presented for young and elderly females and males for each of the amino acids.

Adult↗
PubMed1990

Melatonin concentrations in the sudden infant death syndrome.

To examine a possible relationship between pineal function and the sudden infant death syndrome (SIDS), samples of whole blood, ventricular cerebrospinal fluid (CSF) and/or vitreous humor (VH) were obtained at autopsy from 68 infants (45 male, 23 female) whose deaths were attributed to either SIDS (n = 32, 0.5-5.0 months of age; mean +/- S.E.M., 2.6 +/- 0.2 months) or other causes (non-SIDS, n = 36, 0.3-8.0 months of age 4.3 +/- 0.3 months). The melatonin concentrations were measured by radioimmunoassay. A significant correlation was observed for melatonin levels in different body fluids from the same individual. After adjusting for age differences, CSF melatonin levels were significantly lower among the SIDS infants (91 +/- 29 pmol/l; n = 32) than among those dying of other causes (180 +/- 27; n = 35, P less than 0.05). A similar, but non-significant trend was also noted in blood (97 +/- 23, n = 30 vs. 144 +/- 22 pmol/l, n = 33) and vitreous humor (68 +/- 21, n = 10 vs. 81 +/- 17 pmol/l, n = 15). These differences do not appear to be explainable in terms of the interval between death and autopsy, gender, premortem infection or therapeutic measures instituted prior to death. Diminished melatonin production may be characteristic of SIDS and could represent an impairment in the maturation of physiologic circadian organization.

Age Factors↗
PubMed1990

A randomized double-blind prospective trial of two doses of gestrinone in the treatment of endometriosis.

The purpose of this randomized double blind prospective trial was to study the efficacy and safety of two doses of oral gestrinone in the treatment of endometriosis. Six patients received gestrinone 1.25 mg twice weekly (group I) and six patients received gestrinone 2.5 mg twice weekly (group II). Patients underwent pretreatment and post-treatment laparoscopies and their endometriosis scores were recorded. The mean total endometriosis scores declined significantly from 20.0 +/- 5.2 (mean +/- standard error of the mean) pretreatment to 9.5 +/- 3.9 post-treatment in group I and from 19.1 +/- 4.8 pretreatment to 7.1 +/- 2.1 post-treatment in group II. A total of 67% of patients reported side effects. This study suggests that oral gestrinone 1.25 mg or 2.5 mg twice weekly is efficacious and safe in the treatment of endometriosis.

Adult↗