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PubMed2006

The use of heart rate variability measures to assess autonomic control during exercise.

Heart rate variability (HRV) is a non-invasive indicator of cardiac autonomic modulation at rest. During rhythmic exercise, global HRV decreases as a function of exercise intensity. Measures reflecting sympathovagal interactions at rest do not behave as expected during exercise. This makes interpretation of HRV measures difficult, especially at higher exercise intensities. This problem is further confounded by the occurrence of non-neural oscillations in the high-frequency band due to increased respiratory effort. Alternative data treatments, such as coarse graining spectral analysis (CGSA), have demonstrated expected changes in autonomic function during exercise with some success. The separation of harmonic from fractal and/or chaotic components of HRV and study of the latter during exercise have provided further insight into cardioregulatory control. However, more research is needed. Some cross-sectional differences between HRV in athletes and controls during exercise are evident and data suggest longitudinal changes may be possible. Standard spectral HRV analysis should not be applied to exercise conditions. The use of CGSA and non-linear analyses show much promise in this area. Until further validation of these measures is carried out and clarification of the physiological meaning of such measures occurs, HRV data regarding altered autonomic control during exercise should be treated with caution.

Autonomic Pathways↗
PubMed2003

Comparison of coronary artery dynamics pre- and post-stenting.

Stents have dramatically improved the treatment of coronary artery disease. Since the implantation of stents changes the geometry and dynamics of the coronary artery, it is reasonable to hypothesize that some of these changes may have an important effect on the development of atherosclerosis by modulating the mechanical environment. In this paper, we presented a method to compare the geometric dynamics of the coronary artery before and after stenting using biplane angiography. Two cases are reviewed and a number of parameters are proposed to describe the longitudinal change of the vessel before and after stenting. This analysis technique has the potential to identify some aspects of stent design and procedure that might improve the success rate with this therapeutic approach.

Arteries↗
PubMed1992

Predictive power of various models for longitudinal attachment level change.

Several statistical models that have been suggested in the periodontal literature for describing longitudinal attachment level changes, such as the gradual loss, single-burst, multiple-burst, and random walk models as well as other models introduced in this paper are compared by their power to predict future attachment loss. The data used in this analysis is from 1061 sites of 8 subjects, with moderate to severe periodontal disease, monitored monthly for about a year. This study found that none of the suggested models could significantly outperform the naïve mean predictor, which predicts the future attachment level from the past mean. It was also found that no single model, such as the burst, gradual, or random walk, together with measurement error can fully explain the variation in the data. These results indicate that in the course of one year, the attachment level change may not follow the same model. Consequently, a model that fits well to past data cannot be accurately extended to the future.

Disease Susceptibility↗
PubMed1999

Late onset postpartum thrombocytosis in preeclampsia.

BACKGROUND: During pregnancy, changes in blood coagulation and fibrinolysis create a hypercoagulable state. In the puerperium this thrombogenicity is even higher, and the chance of developing thromboembolism is 3-5 times higher in this period than during pregnancy. In preeclampsia, platelets are activated and play a substantial role in the pathogenesis of the disease. Systematic information on longitudinal changes in platelet number and size postpartum after normotensive and preeclamptic pregnancies is not available. METHODS: We measured platelet number, mean platelet volume and the median volume of the 20% largest platelets in eleven preeclamptic and eleven normotensive pregnant women matched for mode of delivery. The blood samples were taken antepartum and every 2-3 days in the postpartum period until the platelet count decreased/normalized. RESULTS: In the preeclamptic group, the platelet count increased significantly from 240x10(9)/l antepartum to 621x10(9)/l on day 6-14 postpartum (p<0.01). In the control group, the platelet count increased from 214x10(9)/l antepartum to 251x10(9)/l on day 2-5 (p<0.01) and 351x10(9)/l on day 6-14 postpartum (p<0.01). The platelet count was significantly higher in the preeclamptic than in the control group 6-14 days postpartum (p<0.01). Antepartum, mean platelet volume and the median of the 20% largest platelets were significantly higher in the preeclamptic than in the control group. CONCLUSION: The platelet count is significantly increased postpartum both after normotensive, and 2-3 fold more after preeclamptic pregnancies. The time to peak values is between 6-14 days, usually at a time when patients are discharged from hospital.

Adult↗
PubMed2004

Nonindependence of mammalian dental characters.

Studies of mammalian evolution frequently use data derived from the dentition. Dental characters are particularly central for inferring phylogenetic relationships of fossil taxa, of which teeth are often the only recovered part. The use of different aspects of dental morphology as phylogenetic signals implies the independence of dental characters from each other. Here we report, however, that, at least developmentally, most dental characters may be nonindependent. We investigated how three different levels of the cell signalling protein ectodysplasin (Eda) changed dental characters in mouse. We found that with increasing expression levels of this one gene, the number of cusps increases, cusp shapes and positions change, longitudinal crests form, and number of teeth increases. The consistent modification of characters related to lateral placement of cusps can be traced to a small difference in the formation of an early signalling centre at the onset of tooth crown formation. Our results suggest that most aspects of tooth shape have the developmental potential for correlated changes during evolution which may, if not taken into account, obscure phylogenetic history.

Animals↗
PubMed1997

Relationship between concentration of serum leptin and fetal growth.

The serum leptin concentration reflects the amount of adipose tissue in the body. Although fat deposition in the fetus in the third trimester markedly increases, the role of leptin during pregnancy has not been clarified. In the present study, whether or not the serum leptin concentration correlates with growth in utero was investigated, in addition to how leptin levels change in the first few days after birth. One hundred sixteen Japanese infants were divided into term (n = 91) and preterm groups (n = 25). Term infants were divided into 3 subgroups: birth weight appropriate for gestational age (AGA) (n = 44), birth weight large for gestational age (LGA) (n = 28), and birth weight small for gestational age (SGA) (n = 19). Longitudinal changes in the concentration of serum leptin after birth were examined in 48 infants. The serum leptin concentration was determined by RIA. No significant difference in leptin levels between cord sera and infants' sera obtained within the first 6 h of life (n = 28) was observed. Within the first 6 h of life, the concentration of serum leptin in LGA infants (12.8 +/- 10.2 ng/mL) and SGA infants (1.6 +/- 1.1 ng/mL) was significantly higher and lower, respectively, than that in the AGA infants (4.4 +/- 3.0 ng/mL) (P < 0.01). A significant positive correlation was found between the leptin concentration within 6 h of life and birth body weight (r = 0.59, P < 0.01). After birth, the concentration of leptin in LGA and AGA infants significantly decreased to the level in SGA infants within 72 h [corrected] of delivery (P < 0.05). After 72 h [corrected] of life, no significant differences in the concentration of leptin were observed among the three groups, and low levels continued to 7 days of age. These findings indicate that serum level of leptin correlates with fetal body weight gain.

Adult↗
PubMed2002

Acute effects of irradiation on cognition: changes in attention on a computerized continuous performance test during radiotherapy in pediatric patients with localized primary brain tumors.

PURPOSE: To assess sustained attention, impulsivity, and reaction time during radiotherapy (RT) for pediatric patients with localized primary brain tumors. METHODS AND MATERIALS: Thirty-nine patients (median age 12.3 years, range 5.9-22.9) with primary brain tumors were evaluated prospectively using the computerized Conners' continuous performance test (CPT) before and during conformal RT (CRT). The data were modeled to assess the longitudinal changes in the CPT scores and the effects of clinical variables on these changes during the first 50 days after the initiation of CRT. RESULTS: The CPT scores exhibited an increasing trend for errors of omission (inattentiveness), decreasing trend for errors of commission (impulsivity), and slower reaction times. However, none of the changes were statistically significant. The overall index, which is an algorithm-based weighted sum of the CPT scores, remained within the range of normal throughout treatment. Older patients (age >12 years) were more attentive (p < 0.0005), less impulsive (p < 0.07), and had faster reaction times (p < 0.001) at baseline than the younger patients. The reaction time was significantly reduced during treatment for the older patients and lengthened significantly for the younger patients (p < 0.04). Patients with a shunted hydrocephalus (p < 0.02), seizure history (p < 0.0006), and residual tumor (p < 0.02) were significantly more impulsive. Nonshunted patients (p < 0.0001), those with more extensive resection (p < 0.0001), and patients with ependymoma (p < 0.006) had slower initial reaction times. CONCLUSION: Children with brain tumors have problems with sustained attention and reaction time resulting from the tumor and therapeutic interventions before RT. The reaction time slowed during treatment for patients <12 years old. RT, as administered in the trial from which these data were derived, has limited acute effects on changes in the CPT scores measuring attention, impulsiveness, and reaction time.

Adolescent↗
PubMed1999

Initial orthopaedic displacement compared with longitudinal displacement of the maxilla after a forward force application. An experimental study in dogs.

The aim of this study was to compare the initial orthopaedic displacement of the maxilla in vivo and the longitudinal changes after a forward force application. The sample consisted of five 1-year-old dogs. An anterior force of 5 N on the maxilla was applied by a coil spring system pushing between Brånemark implants and a maxillary splint. The initial displacement of the maxilla after force application was measured by means of speckle interferometry. The longitudinal displacement of the maxilla after a force application during 8 weeks was measured by superimposing standardized lateral cephalograms. The initial, as well as the longitudinal, displacement of the maxilla of the dogs was in a forward direction with some counterclockwise rotation. There was no statistical difference between the initial and longitudinal displacement. The biological response after force application during 8 weeks can be predicted by the initial orthopaedic displacement.

Animals↗
PubMed2005

Uterine artery remodeling and reproductive performance are impaired in endothelial nitric oxide synthase-deficient mice.

The progressive rise in uterine blood flow during pregnancy is accompanied by outward hypertrophic remodeling of the uterine artery (UA). This process involves changes of the arterial smooth muscle cells and extracellular matrix. Acute increases in blood flow stimulate endothelial production of nitric oxide (NO). It remains to be established whether endothelial NO synthase (eNOS) is involved in pregnancy-related arterial remodeling. We tested the hypothesis that absence of eNOS results in a reduced remodeling capacity of the UA during pregnancy leading to a decline in neonatal outcome. UA of nonpregnant and pregnant wild-type (Nos3+/+) and eNOS-deficient (Nos3-/-) mice were collected and processed for standard morphometrical analyses. In addition, cross sections of UA were processed for cytological (smoothelin, smooth muscle alpha-actin) and proliferation (Ki-67) immunostaining. We compared the pregnancy-related changes longitudinally and, together with the data on pregnancy outcome, transversally by analysis of variance with Bonferroni correction. During pregnancy, the increases in radius and medial cross sectional area of Nos3-/- UA was significantly less than those of Nos3+/+ UA. Smooth muscle cell dedifferentiation and proliferation were impaired in gravid Nos3-/- mice as deduced from the lack of change in the expression of smoothelin and smooth muscle alpha-actin, and the reduced Ki-67 expression. Until 17 days of gestation, litter size did not differ between both genotypes, but at birth the number of viable newborn pups and their weights were smaller in Nos3-/- than in Nos3+/+ mice. We conclude that absence of eNOS adversely affects UA remodeling in pregnancy, which may explain the impaired pregnancy outcome observed in these mice.

Adaptation, Physiological↗
PubMed1997

Correlates of change in cognitive function in survivors from the Western Collaborative Group Study.

Changes in cognitive function were investigated in 566 subjects 65-86 years old at baseline, who are a subsample of the Western Collaborative Group Study, a cardiovascular epidemiologic study of middle-aged men that began in the 1960s. Cognitive function was assessed in 1986-1988 (baseline) and again in 1992-1994 by three standardized measures: the Benton Visual Retention Test, the Controlled Oral Word Association Test, and the Digit Symbol Substitution (DSS) Test. Longitudinal change in performance was defined as the shift over time in a subject's quartile rank ordering, using the baseline distribution of test scores as a standard. 'Decliners' and 'improvers' in cognitive function were subjects who lost or gained, respectively, two or more quartile ranks on all three tests combined. By this definition, 20% (n = 113) of subjects declined, compared with 17% (n = 95) who improved in cognitive performance from 1986-1988 to 1992-1994. After adjustment for age, education, and physical health, decline in cognitive performance was significantly associated with poor self-perceived health ratings, depression scale scores, and self-reports of physical activity. Rank score change in the DSS Test was the single best predictor of cognitive function at follow-up on a diverse battery of neuropsychological tests.

Aged↗
PubMed2006

Longitudinal and age trends of metabolic syndrome and its risk factors: the Family Heart Study.

BACKGROUND: We report longitudinal changes in the metabolic syndrome (MetS) in 2,458 participants from 480 families in the Family Heart Study. Participants were examined between 1994-96 (FHS-T1) and 2002-03 (FHS-T2), about 7.4 years apart. Additionally, the impact of medication on estimates of MetS prevalence, and associations of MetS with prevalent coronary heart disease (CHD) and type 2 diabetes (T2D) were studied. METHODS: Three definitions for MetS prevalence were considered. One represented the original (o) National Cholesterol Education Program (NCEP) MetS criteria. Two others considered the confounding of medications effects, respectively (m) lipid medications constituted a categorical diagnostic criterion for lipids variables, and (c) lipids and blood pressure variables were corrected with average clinical trials medications effects. Logistic regression of MetS on CHD and T2D, as well as the trend analysis of MetS by age, were performed. RESULTS: MetS increased from 17.1% in FHS-T1(o) to 28.8% in FHS-T2(o); from 19.7% in FHS-T1(m) to 42.5% in FHS-T2(m); and from 18.4% in FHS-T1(c) to 33.6% in FHS-T2(c). While we observed adverse changes in all risk factors, the greatest increase was for waist circumference (25%). The percentages of MetS were about 2 to almost 3 times higher in ages 50 years and older than in younger ages. The odds of having prevalent CHD were about 2.5 times higher in the subjects classified with MetS than without. CONCLUSION: MetS percentages increased noticeably longitudinally and cross-sectionally with older age. These conclusions were reached with and without considering medication use, but correcting risk factors for medications use affects the MetS prevalence estimates. As found in other studies, MetS was associated with increased odds for prevalent CHD.

Journal Article↗
PubMed1984

Professional socialization in dentistry: a longitudinal analysis of changes in students' expected professional rewards.

In this continuing longitudinal study on professional socialization of dental students, further analysis of the changes occurring in their attitudes towards the chosen profession is carried out. Although students' basic norms and values remained generally unchanged over time, disillusionment set in with regard to most of the expected professional rewards, in particular the anticipated 'intellectual challenge'. Unlikely, medical students who served as a comparison showed greatest disparity between expectation at admission and at graduation with regard to the economic side of their profession ('high income' and 'job security'). In spite of the growing cynicism of dental students throughout the years of education, apparent in the steady increase in expectations of extrinsic rewards and decreases in expectations of intrinsic rewards, these changes may be only situational in nature, for the same group of graduates showed a return to a more idealistic outlook of their profession 8 years post-graduation.

Adult↗
PubMed2002

Seasonal variations in clinical and laboratory variables among chronic hemodialysis patients.

Seasonal variations in BP among chronic hemodialysis patients have been reported. It was hypothesized that other characteristics of these patients might also vary with the seasons. Twenty-one clinical and laboratory variables were examined for seasonal variations among 1445 patients enrolled in the Hemodialysis Study, sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases. Mixed-effects models were applied to longitudinal changes (up to 45 mo) for individual patients for 19 of the 21 variables, which were measured at least twice each year, to determine the seasonal component of each variable. Seasonal variations in the other two variables, i.e., protein and energy intakes determined from annual dietary records, were assessed in cross-sectional comparisons of intakes of patients entering the study at different time points. Thirteen of the 21 variables examined demonstrated statistically significant (P < 0.01) seasonal components in their longitudinal variations. Predialysis blood urea nitrogen concentrations peaked in March, which coincided approximately with the peak protein catabolic rates, as well as protein and energy intakes (determined by dietary recall). Predialysis systolic and diastolic BP values were highest in winter and lowest in summer, corroborating previous reports. In addition, the lower predialysis BP values in summer were associated with higher outdoor temperatures and less interdialytic fluid gain. The mean predialysis hematocrit values were highest in July, which could not be attributed solely to the estimated changes in plasma volume. Seasonal variations in clinical and laboratory variables occur commonly among chronic hemodialysis patients. The reasons for most of these variations are not apparent and require further investigation. Nonetheless, failure to consider these variations might lead to biases in the interpretation of clinical studies. In addition, awareness of these variations might facilitate the interpretation of laboratory results and the clinical treatment of these patients.

Adult↗
PubMed1999

Longitudinal cognitive and motor changes among presymptomatic Huntington disease gene carriers.

OBJECTIVE: To determine whether longitudinal changes in cognitive and motor function can be detected among clinically presymptomatic individuals carrying the Huntington disease (HD) allele. DESIGN: A longitudinal, case-control, double-blind study comparing presymptomatic gene carriers and non-gene carriers at risk for HD examined an average of 3.7 years apart. SETTING: The Department of Medical and Molecular Genetics at a general clinic research center in Indianapolis, Ind. PARTICIPANTS: A sample of 43 at-risk individuals consisting of presymptomatic gene carriers (n = 12) and non-gene carriers (n = 31). MEASURES: Huntington disease gene status was determined by molecular testing of the HD gene. Subscales from the Wechsler Adult Intelligence Scale-Revised and a quantified neurologic rating scale were administered. RESULTS: Scores on the digit symbol subscale of the Wechsler Adult Intelligence Scale-Revised (P<.05) and 2 neurologic variables-optokinetic nystagmus (P<.01) and rapid alternating movements (P<.005)-declined more rapidly among presymptomatic gene carriers than among non-gene carriers. At follow-up examination, compared with nongene carriers, presymptomatic gene carriers had significantly lower scores on the digit symbol subscale (P = .02) and for 4 neurologic variables-rapid alternating movements (P<.005), optokinetic nystagmus (P<.001), overall ocular movements (P<.02), and chorea of the trunk (P<.02). CONCLUSIONS: Psychomotor speed, optokinetic nystagmus, and rapid alternating movements demonstrated significant decline early in the pathological process of HD. These results suggest that subtle worsening of psychomotor, oculomotor, and motor functions occurs before the onset of signs sufficient to make a clinical diagnosis in individuals who have inherited the HD allele.

Adult↗
PubMed1995

Longitudinal and behavioral analysis of masculinity and femininity in marriage.

Spouses' masculinity and femininity were examined in relation to longitudinal change in marital satisfaction and behavior displayed in a problem-solving discussion. Results indicated, first, that wives' satisfaction declined to the extent that their husband endorsed fewer desirable masculine traits (Study 1) and more undesirable masculine traits (Study 2). Second, masculinity and femininity covaried with problem-solving behavior, particularly for behavioral sequences involving husbands' responses to wives' negative behavior. Finally, the relation between husbands' masculinity and change in wives' satisfaction was not mediated by husbands' behavior; instead, sex role and behavioral variables made independent contributions to change in wives' satisfaction. These results are important because they highlight the value of examining intraindividual and interpersonal variables when determining how marriages improve and deteriorate.

Adult↗
PubMed2000

Low frequency depression of H-reflexes in humans with acute and chronic spinal-cord injury.

We measured low-frequency depression of soleus H-reflexes in individuals with acute (n=5) and chronic (n=7) spinal-cord injury and in able-bodied controls (n=7). In one acute subject, we monitored longitudinal changes in low-frequency depression of H-reflexes over 44 weeks and examined the relationship between H-reflex depression and soleus-muscle fatigue properties. Soleus H-reflexes were elicited at 0.1, 0.2, 1, 5, and 10 Hz. The mean peak-to-peak amplitude of ten reflexes at each frequency was calculated, and values obtained at each frequency were normalized to 0.1 Hz. H-reflex amplitude decreased with increasing stimulation frequency in all three groups, but H-reflex suppression was significantly larger in the able-bodied and acute groups than in the chronic group. The acute subject who was monitored longitudinally displayed reduced low-frequency depression with increasing time post injury. At 44 weeks post injury, the acute subject's H-reflex depression was similar to that of chronic subjects, and his soleus fatigue index (assessed with a modified Burke fatigue protocol) dropped substantially, consistent with transformation to faster muscle. There was a significant inverse correlation over the 44 weeks between the fatigue index and the mean normalized H-reflex amplitude at 1, 5, and 10 Hz. We conclude that: (1) the chronically paralyzed soleus muscle displays impaired low-frequency depression of H-reflexes, (2) attenuation of rate-sensitive depression in humans with spinal-cord injury occurs gradually, and (3) changes in H-reflex excitability are generally correlated with adaptation of the neuromuscular system. Possible mechanisms underlying changes in low-frequency depression and their association with neuromuscular adaptation are discussed.

Acute Disease↗
PubMed1985

Longitudinal analysis of functional disabilities in older men.

This study examined the prevalence of functional disabilities in a representative sample of older American men. Longitudinal changes in various disabilities and the effects of such changes on self-appraised health, normal role function, mobility and self-sufficiency in personal care were analyzed. The relationship between disabilities and survivorship was also investigated. The analysis showed that sizable percentages of men report motor-sensory dysfunctions, with blacks experiencing higher prevalence rates than whites. The risk of functional disablement rises with age and increases the likelihood of reporting unfavorable health outcomes or handicaps. There is also some evidence that functional capacities are restored and that these changes lead to more favorable health outcomes. The analysis showed finally that functional disabilities are strong predictors of mortality.

Black or African American↗
PubMed1993

Does television viewing increase obesity and reduce physical activity? Cross-sectional and longitudinal analyses among adolescent girls.

To examine the relationships between hours of television viewing and adiposity and physical activity among female adolescents, a cohort study with follow-up assessments 7, 14, and 24 months after baseline was conducted. All sixth- and seventh-grade girls (N = 971) attending four northern California middle schools were eligible to participate. Six hundred seventy-one students had sufficient data for baseline cross-sectional analyses, and 279 students in a no-intervention cohort had sufficient data for longitudinal analyses. The baseline sample had a mean age of 12.4 years and was 43% white, 22% Asian, 21% Latino, 6% Pacific Islander, 4% black, 2% American Indian, and 2% other. Hours of after-school television viewing, level of physical activity, and stage of sexual maturation were assessed with self-report instruments. Height, weight, and triceps skinfold thickness were measured and body mass index (ratio of weight [in kilograms] to height [in meters] squared) and triceps skinfold thickness were adjusted by level of sexual maturity for the analyses. Baseline hours of after-school television viewing was not significantly associated with either baseline or longitudinal change in body mass index or triceps skinfold thickness. Baseline hours of after-school television viewing was weakly negatively associated with level of physical activity in cross-sectional analyses but not significantly associated with change in level of physical activity over time. All results were essentially unchanged when adjusted for age, race, parent education, and parent fatness. Among adolescent girls, television viewing time appears to have only weak, if any, meaningful associations with adiposity, physical activity, or change in either over time.

Adolescent↗