Biomedical subjects

M Litaker

Publications and source records attributed to M Litaker.

At least 19 recordsLinked to original sources

PubMed2001

Morphological differences between minicolumns in human and nonhuman primate cortex.

Our study performed a quantitative investigation of minicolumns in the planum temporale (PT) of human, chimpanzee, and rhesus monkey brains. This analysis distinguished minicolumns in the human cortex from those of the other nonhuman primates. Human cell columns are larger, contain more neuropil space, and pack more cells into the core area of the column than those of the other primates tested. Because the minicolumn is a basic anatomical and functional unit of the cortex, this strong evidence showed reorganization in this area of the human brain. The relationship between the minicolumn and cortical volume is also discussed.

Adaptation, Physiological↗

PubMed2001

Cardiovascular (CV) responsivity and recovery to acute stress and future CV functioning in youth with family histories of CV disease: a 4-year longitudinal study.

Blood pressure (BP) and heart rate (HR) data obtained during supine rest, in response to and recovery from four laboratory stressors in a baseline year were used to predict supine resting BP and HR values obtained during each of four consecutive annual follow-up evaluations. Subjects were 385 normotensive youth [95 African American (AA) males, 106 AA females, 92 European American (EA) males, 92 EA females] (mean age 12.7+/-2.6 at baseline year) with a positive family history of cardiovascular disease (CVD). During the baseline evaluation subjects were presented with four laboratory stressors (namely, postural change, video game challenge, social competence interview, and parent--child conflict discussion). The BP and HR values taken during each of the laboratory stressors and during the post stressor recovery periods were converted to z-scores which were averaged to yield aggregate measures for systolic and diastolic BP and HR responsivity and recovery. The data obtained during the baseline evaluation were subsequently used to predict the follow-up values of supine resting BP and HR. The prediction models were fairly consistent across each of the 4 follow-up years. Responsivity or recovery accounted for up to 6% of the total variance after accounting for baseline values. Within the prediction models responsivity or recovery accounted for 4--56% of the variance. The predictive value of the derived models did not decline from one annual evaluation to the next over the length of the study. CV recovery may supplement resting and responsivity in the prediction of future development of CVD

Adolescent↗

PubMed2001

Lateralization of minicolumns in human planum temporale is absent in nonhuman primate cortex.

Gross analyses of large brain areas, as in MRI studies of macroanatomical structures, average subtle alterations in small regions, inadvertently missing significant anomalies. We developed a computerized imaging program to microscopically examine minicolumns and used it to study Nissl-stained slides of normal human, chimpanzee, and rhesus monkey brains in a region of the planum temporale. With this method, we measured the width of cell columns, the peripheral neuropil space, the spacing density of neurons within columns, and the Gray Level index per minicolumn. Only human brain tissue revealed robust asymmetry in two aspects of minicolumn morphology: wider columns and more neuropil space on the left side. This asymmetry was absent in chimpanzee and rhesus monkey brains.

Algorithms↗

PubMed2000

Visceral adipose tissue and markers of the insulin resistance syndrome in obese black and white teenagers.

OBJECTIVE: To determine the relationships between visceral and general adiposity, cardiovascular fitness, and markers of the insulin resistance syndrome in obese black and white teenagers. RESEARCH METHODS AND PROCEDURES: Cross-sectional survey of 81 obese 13- to 16-year-old youths. Visceral adipose tissue was measured with magnetic resonance imaging, and percentage body fat was measured with dual-energy X-ray absorptiometry. Cardiovascular fitness was assessed with a submaximal treadmill test. Fasting blood samples were analyzed for lipids/lipoproteins and insulin. Resting blood pressure was obtained using an automated cuff. RESULTS: Visceral adipose tissue was significantly correlated with unfavorable levels of: triacylglycerol (r = 0.27, p < 0.05), total cholesterol (r = 0.27, p < 0.05), high-density lipoprotein cholesterol (r = -0.26, p < 0.05), the ratio of total cholesterol/high-density lipoprotein cholesterol (r = 0.42, p < 0.01), low-density lipoprotein cholesterol (r = 0.27, p < 0.05), apolipoprotein B (r = 0.38, p < 0.01), and systolic blood pressure (r = 0.30, p < 0.01). Multiple regression analyses revealed that visceral adipose tissue was more powerful than percentage body fat for explaining variance in lipoproteins (e.g., for the ratio of total cholesterol/high-density lipoprotein cholesterol, r2 = 0.13, p < 0.01, and for systolic blood pressure, r2 = 0.07, p < 0.05). Ethnicity was the most powerful of the demographic predictors for blood lipids (r2 = 0.15 for triacylglycerol with lower levels in blacks; r2 = 0.10 for high-density lipoprotein cholesterol with higher levels in blacks; r2 = 0.06 for the ratio of total cholesterol/high-density lipoprotein cholesterol with lower levels in blacks). Cardiovascular fitness was not retained as a significant predictor of markers of the insulin resistance syndrome. DISCUSSION: Some of the deleterious relationships between visceral adiposity and markers for the insulin resistance syndrome seen in adults were already present in these obese young people.

Adipose Tissue↗

PubMed1999

Prediction of visceral adipose tissue from simple anthropometric measurements in youths with obesity.

OBJECTIVE: Although visceral adipose tissue (VAT) is the component of body composition most highly associated with cardiovascular risk factors, its measurement requires expensive procedures, such as magnetic resonance imaging. This study examined the ability of simple demographic and anthropometric measurements to predict magnetic resonance imaging-derived VAT in 76 apparently healthy, black and white youths with obesity who were 7 years to 16 years of age. RESEARCH METHODS AND PROCEDURES: Stepwise multiple linear regression was used to develop a prediction equation for VAT based on 13 simple anthropometric variables (height, weight, body mass index, triceps skinfold, calf skinfold, sagittal diameter, waist circumference, hip circumference, thigh circumference, waist/hip ratio, waist/thigh ratio, sagittal diameter/thigh ratio, and percent body fat from the sum of calf and triceps skinfolds) and three demographic variables (age, gender and ethnicity). RESULTS: The stepwise multiple regression procedure yielded a final model that included two anthropometric variables (sagittal diameter and waist/hip ratio) and one demographic variable (ethnicity). The prediction equation was: VAT = - 124.06+ 16.67 (ethnicity)+4.15 (sagittal diameter)+100.89 (waist/hip ratio), where ethnicity was coded as 0= black and 1 = white. The model explained 63% of the variance in VAT and was associated with a measurement error of 23.9%. DISCUSSION: Although the model seems to lack sufficient explanatory power for routine use in clinical settings with individual patients, it may have some utility in epidemiological studies given its relatively small (<25%) standard error of estimate.

Adipose Tissue↗

PubMed1999

Effect of physical training and its cessation on percent fat and bone density of children with obesity.

OBJECTIVE: We determined the effect of 4-month periods of physical training (PT) and detraining on percent fat (percent fat) and bone density of children with obesity. RESEARCH METHODS AND PROCEDURES: Subjects were 79 7- to 11-year-old children with obesity; 34 were white, 44 were black, and 1 was Asian, 26 were male and 53 were female. They were randomly assigned to two groups: group 1 engaged in PT for the first 4 months, while group 2 engaged in PT during the second 4 months. Body composition was measured with dual energy absorptiometry, and diet was measured with 4 days of recall for each 4-month period. PT was offered 5 days/week for 40 minutes/session, heart rate monitors were worn, and no dietary information was given; mean attendance was 80%, and mean heart rate per session was 157 bpm. RESULTS: Group by time interactions across the three time-points (from analysis of variance) were significant for percent fat (p = <0.001) and bone density (p = 0.045). Both groups declined in percent fat during the periods of PT, by an average of 1.6% fat units; in the 4 months after cessation of PT, group 1 increased by 1.3% fat. In both groups, bone density increased more during periods of PT (0.025 g/cm2) than during periods of no PT (0.010 g/cm2). No significant PT vs. no-PT differences were found for dietary intake of energy, macronutrients, or calcium. DISCUSSION: This study suggests that regular exercise, without dietary intervention, can enhance the body composition of children with obesity.

Adipose Tissue↗

PubMed1999

Effects of exercise training and its cessation on components of the insulin resistance syndrome in obese children.

OBJECTIVE: To determine the effect of exercise training (ET) on components of the insulin resistance syndrome (IRS) in obese children. DESIGN: Randomized, modified cross-over study, with subjects assigned to one of two conditions: (1) 4 months of ET followed by 4 months of no-ET; or (2) 4 months of no-ET followed by 4 months of ET. Measurements were made at three time points: 0, 4 and 8 months. SUBJECTS: 79 obese, but otherwise healthy children (age: 7-11 y, percent fat (%fat) 27-61%). MEASUREMENTS: Plasma lipid and lipoprotein concentrations, plasma insulin and glucose concentrations; %fat; submaximal heart rate (HR) as an index of fitness. EXERCISE TRAINING: ET was offered 5 d/week 40 min/d. For the 73 children who completed 4 months of ET, the mean attendance was 80% (that is, 4 d/week) and the average HR during ET was 157 bpm. RESULTS: Significant (P < 0.05) group x time interactions were found for plasma triglyceride (TG) and insulin concentrations and %fat. The average change for both groups, from just before ET to just after the 4 month ET was -0.24 mmol.l-1 for TG, -25.4 pmol.l-1 for insulin and -1.6 units for %fat. When Group 1 ceased ET, over the following 4 month period the average change for insulin was +26.6 pmol.l-1 and for %fat +1.3 units. CONCLUSION: Some components (plasma TG, insulin, %fat) of the IRS are improved as a result of 4 months of ET in obese children. However, the benefits of ET are lost when obese children become less active.

Analysis of Variance↗

PubMed1999

Plasma leptin concentrations in obese children: changes during 4-mo periods with and without physical training.

BACKGROUND: Little is known about the effects of physical training on plasma leptin concentrations in children. OBJECTIVE: We sought to determine the effects of 4-mo periods with and without physical training on leptin in obese children and to explore the determinants of leptin at baseline and in response to physical training. DESIGN: Participants were 34 obese 7-11-y-old children randomly assigned to engage in physical training during either the first or second 4 mo of the 8-mo study. RESULTS: Total body composition, visceral adiposity, and insulin were all positively correlated with leptin at baseline (P < or = 0.05); however, only fat mass was retained in the final stepwise regression (P = 0.0001, R2 = 0.57). Leptin decreased during the 4-mo periods of physical training and increased in the 4 mo after cessation of physical training (P < 0.001 for the time by group interaction). Decreases in leptin were greatest in children with higher pretraining leptin concentrations, those whose total mass increased least, and those whose insulin concentrations decreased most (P < or = 0.05); only pretraining leptin concentration (P = 0.009) and change in total mass (P = 0.0002) were retained in the final regression (R2 = 0.53). CONCLUSIONS: In obese children, leptin concentration decreased during 4 mo of physical training and increased during a subsequent 4-mo period without physical training, fat mass was highly correlated with baseline leptin, and greater reductions in leptin during 4 mo of physical training were seen in children with higher pretraining leptin and in those whose total mass increased least.

Absorptiometry, Photon↗

PubMed1999

Correlates of individual differences in body-composition changes resulting from physical training in obese children.

BACKGROUND: No studies have been reported in children that assess correlates of body-composition changes in response to a physical training intervention. OBJECTIVE: The hypothesis studied was that variation in diet and physical activity would explain a significant portion of the interindividual variation in the response of body composition to physical training. DESIGN: The participants were 71 obese children aged 7-11 y (22 boys, 49 girls; 31 whites, 40 blacks). Body composition was measured by dual-energy X-ray absorptiometry, physical activity by a 7-d recall interview, and diet by two, 2-d recalls. The children underwent 4 mo of physical training. RESULTS: The mean attendance was 4 d/wk, the mean (+/-SD) heart rate for the 40-min sessions was 157 +/- 7 beats/min, and the mean energy expenditure was 946 +/- 201 kJ/session. On average, the percentage body fat decreased significantly in the total group, and total mass, fat-free soft tissue, bone mineral content, and bone mineral density increased, but there was a good deal of individual variability. Multiple regression models indicated that in general, more frequent attendance, being a boy, lower energy intake, and more vigorous activity were associated with healthier body-composition changes with physical training. Ethnicity was not retained as a correlate of the change of any component of body composition. CONCLUSIONS: In obese children, age, vigorous activity, diet, and baseline percentage body fat together accounted for 25% of the variance in the change in percentage body fat with physical training.

Absorptiometry, Photon↗

PubMed1999

Effects of physical training and its cessation on the hemostatic system of obese children.

BACKGROUND: Physical training can improve hemostatic function in adults, thereby reducing heart disease risk, but no information is available in children on whether physical training can enhance hemostatic function. OBJECTIVE: The purpose of this investigation was to examine the effects of a physical training program on hemostatic variables in a biethnic group of obese children. DESIGN: Children were randomly assigned to 2 groups. Group 1 participated in physical training for 4 mo and then ceased physical training for 4 mo, whereas group 2 did no physical training for the first 4 mo and then participated in physical training for 4 mo. Plasma hemostatic variables [fibrinogen, plasminogen activator inhibitor 1 (PAI-1), and D-dimer) were measured at months 0, 4, and 8. RESULTS: Analyses of variance revealed no significant group-by-time interactions for the hemostatic variables. When data from both groups were combined there was a significant decrease in D-dimer after 4 mo of physical training (P < 0.05). Factors explaining individual differences in responsiveness to the physical training revealed that individuals with greater percentage fat before physical training showed greater reductions in fibrinogen and D-dimer, and that blacks showed greater reductions in D-dimer than whites (P < 0.05). Stepwise multiple linear regression showed that only higher prephysical training concentrations of fibrinogen, PAI-1, and D-dimer explained significant proportions of the variation in changes in these variables. CONCLUSIONS: In obese children, 4-mo periods of physical training did not lead to significant changes in hemostatic variables. Children with greater adiposity and concentrations of hemostatic factors before physical training showed greater reductions in hemostatic variables after physical training than did children with lesser values.

Analysis of Variance↗

PubMed1999

Effect of physical training on total and visceral fat in obese children.

PURPOSE: Children with high levels of total body fat mass (TFM) and visceral adipose tissue (VAT) have elevated levels of certain risk factors for coronary artery disease and non-insulin-dependent diabetes mellitus. We tested the hypothesis that controlled physical training, without dietary intervention, would have a favorable impact on VAT and percent body fat (%BF) in obese children. METHODS: A volunteer sample of 74 obese children, 7-11 yr of age, accepted random assignment to physical training or control groups. Before and after 4 months of intervention, measurements were obtained for VAT, TFM, %BF, daily physical activity, and cardiovascular fitness. The intervention involved 4 months of controlled physical training 5 d x wk(-1), 40 min per session, at a mean heart rate (HR) of 157 beats x min(-1). The estimated energy expenditure (EE) per training session was 925+/-201 kJ. RESULTS: Compared with the control group, the physical training group declined significantly in %BF (delta = -2.2%) (P < 0.01), TFM (delta = -3.1%) (P < 0.01), and subcutaneous abdominal adipose tissue (delta = - 16.1%) (P < 0.05), and increased significantly in fat-free mass (delta = +6.1%) (P < 0.05) and moderate-to-very hard physical activity (delta = +14.1%) (P < 0.05). The increase in VAT was significantly less in the physical training group (delta = +0.5%) as compared with that in the control group (delta = +8.1%) (P < 0.05). CONCLUSIONS: This study showed that during physical training obese children: 1) were capable of participating in a substantial amount of high intensity physical training over a 4-month period: 2) accumulated significantly less VAT as compared with nonexercising controls; and 3) experienced other beneficial changes in total and regional body composition.

Abdomen↗

PubMed1998

Fat distribution and hemostatic measures in obese children.

We examined the relation of general and visceral adiposity to plasma hemostatic factors [fibrinogen, D-dimer, and plasminogen activator inhibitor 1 (PAI-1)] in obese boys and girls 7-11 y of age (n = 41). Boys had significantly greater fibrinogen and D-dimer concentrations than girls (P < 0.05). whereas blacks had significantly greater fibrinogen and D-dimer concentrations than whites (P < 0.05). Univariate analyses revealed that fibrinogen was positively associated with percentage body fat (%BF) (r = 0.42, P < 0.01), subcutaneous abdominal adipose tissue (SAAT) (r = 0.40, P < 0.01), total fat mass (r = 0.42, P < 0.01), and body mass index (r = 0.41, P < 0.01). PAI-1 was positively associated with visceral adipose tissue (VAT) (r = 0.49, P < 0.01), SAAT (r = 0.32, P < 0.05), fat-free mass (r = 0.50, P < 0.01), and insulin (r = 0.61, P < 0.001). D-Dimer was positively associated with %BF (r = 0.40, P < 0.01), SAAT (r = 0.37, P < 0.05), total fat mass (r = 0.40, P < 0.01), and body mass index (r = 0.43, P < 0.01). Multiple regression analysis revealed that for fibrinogen, sex and higher %BF explained significant independent portions of the variance. For PAI-1, higher amounts of VAT and fat-free mass were significant predictors. For D-dimer, ethnicity was a significant predictor. These results suggest that general adiposity and VAT may play a role in regulating plasma hemostatic factors in obese children. Even early in childhood, adiposity is associated with unfavorable concentrations of hemostatic factors that are in turn implicated in cardiovascular morbidity and mortality later in life.

Adipose Tissue↗

PubMed1997

Long-term stroke risk in children with sickle cell disease screened with transcranial Doppler.

Stroke is an important complication of sickle cell disease. Stroke prediction is clinically important because it offers the possibility of primary prevention. In 1992, transcranial Doppler (TCD) evidence of elevated intracranial internal carotid or middle cerebral artery velocity was demonstrated to be associated strongly with an increased risk of ischemic stroke. This study extends the original study and includes 125 more children, longer follow-up, and intracranial hemorrhage in the stroke-risk model. Elevated time averaged mean maximum blood flow velocity, especially when velocity is 200 cm/sec or greater by TCD, was associated strongly with stroke risk. The cases not predicted by TCD point to the need for more information on the optimal timing of TCD surveillance for stroke risk.

Adolescent↗

PubMed1996

Assessment of older combat veterans with the clinician-administered PTSD scale.

A study of the posttraumatic stress disorder (PTSD) among older combat veterans of World War II and the Korean Conflict was conducted. The Clinician-Administered PTSD Scale (CAPS) was given to 125 older combat veterans, along with a computerized variant of the Structured Clinical Interview for DSM-III-R for PTSD, the SCID-DTREE. (The SCID-DTREE was itself validated against the full SCID). Results showed the CAPS to be a good discriminator of PTSD: Out of the 125 cases, only 9 were misclassified using the SCID-DTREE as the base measure, a 93% efficiency. An alpha on the full CAPS was .95. This suggests that the CAPS is an appropriate scale for use with older combat veterans.

Aged↗

PubMed1996

Prenatal diagnosis of left ventricular aneurysm in the late second trimester: a case report.

Fetal echocardiography in a 24-year-old woman at 24 weeks' gestation demonstrated a left ventricular aneurysm and pericardial effusion. The patient was treated with oral digoxin followed by intensive antepartum monitoring. Intrauterine fetal demise occurred at 31 weeks. The autopsy confirmed the presence of an apical left ventricular aneurysm. This is a rare congenital cardiac anomaly, which has been reported in only three prior cases. This represents the earliest prenatal diagnosis of this condition.

Adult↗

PubMed1996

Body-composition measurement in 9-11-y-old children by dual-energy X-ray absorptiometry, skinfold-thickness measurements, and bioimpedance analysis.

We compared, in 9-11-y-old children (n=43), three measures of body composition: dual-energy X-ray absorptiometry (DXA), skinfold thickness, and bioimpedance analysis (BIA). The intraclass correlation coefficient (ICC), Bland-Altman procedure, and Spearman rank correlation were used to determine test-retest reliabilities of the three methods and to compare methods. For DXA measurements, the rank correlation between fat-free soft tissue and fat-free mass (FFM) was > 0.99, indicating that bone mineral content did not provide independent information. Thus, subsequent analyses used the two-compartment model (ie, fat mass and FFM) for all three techniques, focusing especially on values for percentage of fat. The test-retest reliabilities for all methods were high (ICCs > 0.994 and no significant differences between trials 1 and 2). The range of individual differences from trial 1 to trial 2 and Bland-Altman limits of agreement suggested that the reliability was greatest for DXA, followed by BIA and skinfold-thickness measurement. The percentage of fat values for the three methods were highly intercorrelated (all Spearman r values > 0.83). However, there was a systematic tendency (P < 0.01) for DXA values (mean: 23.98) to be higher than those derived from skinfold-thickness measurements (mean: 21.05) and BIA (mean: 21.52). The variance in percentage of fat values for BIA was significantly smaller than that for the other two techniques. These findings, along with rather large limits of agreement derived from the Bland-Altman procedure, suggest that the methods should not be used interchangeably.

Absorptiometry, Photon↗

PubMed1993

Noninvasive detection of Chlamydia trachomatis in men: a comparison of two immunoassay tests.

This investigation compared a rapid enzyme immunoassay test and an enzyme-amplified immunoassay test with culture for the noninvasive detection of Chlamydia trachomatis urethritis in men. Urine specimens from 108 male subjects were evaluated for the presence of C trachomatis antigen, using the Kodak Surecell Chlamydia rapid enzyme immunoassay test and IDEIA Chlamydia enzyme-amplified immunoassay test. The test results were then compared with urethral C trachomatis culture and urethral Gram's stain analyses. Performance characteristics of the two tests were similar. The rapid chlamydial enzyme immunoassay test demonstrated several clinical advantages. Appropriate use of these tests may decrease patient morbidity and clarify organism etiology for enhanced specific medical care of urethritis in men.

Adult↗

PubMed1993

Chlamydial cervical infections in rural and urban pregnant women.

The purpose of this investigation was to determine the incidence of cervicitis due to Chlamydia trachomatis in rural pregnant women, urban pregnant women, and urban nonpregnant women in Georgia. Evaluation of endocervical chlamydial cultures from 447 women showed prevalence rates for C trachomatis cervicitis of 12% in the urban pregnant group, 7% in urban nonpregnant women, and 21% in rural pregnant women. Fewer rural pregnant women (2%) reported a previous history of C trachomatis cervicitis than urban pregnant women (9%) and urban nonpregnant women (19%). Data from this study imply that screening for C trachomatis may be done less frequently in rural women than in urban women. The high prevalence of C trachomatis infection observed in rural pregnant women emphasizes the importance of routinely screening this group as currently recommended. Laboratory testing for C trachomatis may be overlooked because of insufficient funds and an emphasis on other sexually transmitted diseases.

Adult↗