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PubMed2002

Sequential MR imaging of denervated muscle: experimental study.

BACKGROUND AND PURPOSE: MR changes in denervated muscles have been reported to occur within days up to several weeks after peripheral nerve damage. The purpose of this experimental study was to investigate the longitudinal changes in denervated muscles by using MR imaging. METHODS: In 12 Lewis rats, the left sciatic nerve was transected at the level of the proximal thigh. MR imaging of both legs was performed before and 1 hour, 24 hours, 48 hours, 7 days, 14 days, 28 days, and 2 months after the procedure. The MR protocol included T1-weighted spin-echo, T2-weighted double turbo spin-echo, and turbo inversion recovery magnitude (TIRM) sequences obtained in the axial plane. Signal intensities (T2-weighted double turbo spin-echo and TIRM sequences) and the T2 TR (T2-weighted double turbo spin-echo sequence) were recorded for the soleus, peroneal, and gracilis muscles of both sides. Moreover, the circumferences of both lower legs were determined on the basis of T1-weighted images. RESULTS: Twenty-four hours after denervation, a signal intensity increase in the denervated peroneal and soleus muscles was present on TIRM images. On T2-weighted images, only the peroneal muscle exhibited slightly increased signal intensities and T2 TR. Forty-eight hours after nerve transection, the denervated soleus and peroneal muscles revealed prolonged T2 TR and marked increased signal intensities on T2-weighted and TIRM images when compared with the contralateral side, which further increased at or less than 2 months after denervation. Muscle atrophy of the denervated muscles was present as early as 7 days after denervation and was also increased at follow-up examinations. CONCLUSION: The TIRM sequence is more sensitive than is T2-weighted imaging in the detection of signal intensity changes in denervated muscle. These changes occur as early as 24 (TIRM sequence) and 48 (T2-weighted sequence) hours, respectively, after complete transection of the sciatic nerve in rats and precede muscle atrophy. The sensitivity to early signal intensity changes in denervated muscles may support the use of MR imaging in the diagnosis of peripheral nerve lesions.

Animals↗
PubMed2006

Associations between changes in hemoglobin and administered erythropoiesis-stimulating agent and survival in hemodialysis patients.

Although treating anemia of chronic kidney disease by erythropoiesis-stimulating agents (ESA) may improve survival, most studies have examined associations between baseline hemoglobin values and survival and ignored variations in clinical and laboratory measures over time. It is not clear whether longitudinal changes in hemoglobin or administered ESA have meaningful associations with survival after adjustment for time-varying confounders. With the use of time-dependent Cox regression models, longitudinal associations were examined between survival and quarterly (13-wk averaged) hemoglobin values and administered ESA dose in a 2-yr (July 2001 to June 2003) cohort of 58,058 maintenance hemodialysis patients from a large dialysis organization (DaVita) in the United States. After time-dependent and multivariate adjustment for case mix, quarterly varying administered intravenous iron and ESA doses, iron markers, and nutritional status, hemoglobin levels between 12 and 13 g/dl were associated with the greatest survival. Among prevalent patients, the lower range of the recommended Kidney Disease Quality Outcomes Initiative hemoglobin target (11 to 11.5 g/dl) was associated with a higher death risk compared with the 11.5- to 12-g/dl range. A decrease or increase in hemoglobin over time was associated with higher or lower death risk, respectively, independent of baseline hemoglobin. Administration of any dose of ESA was associated with better survival, whereas among those who received ESA, requiring higher doses were surrogates of higher death risk. In this observational study, greater survival was associated with a baseline hemoglobin between 12 and 13 g/dl, treatment with ESA, and rising hemoglobin. Falling hemoglobin and requiring higher ESA doses were associated with decreased survival. Randomized clinical trials are required to examine these associations.

Aged↗
PubMed1996

Coal mine dust exposure and spirometry in experienced miners.

In a previous study of new miners from the National Study of Coal Workers' Pneumoconiosis (NSCWP), researchers examined changes in spirometry values associated with coal mine dust exposure (Br J Ind Med 1993; 50:929-937). An unusual pattern of dust-related effects was observed: initial sharp decrements in FVC and FEV1 were followed by partial recovery. In the current study, similar methods were used to analyze data from experienced miners. Each of 1,915 male subjects contributed data from two of the NSCWP field surveys: either Round 1 (1969-71) and Round 2 (1972-75) and Round 4 (1985-88). From the cross-sectional analysis at Round 1 or Round 2 (R1/R2), changes of +0.6 ml FVC and -0.5 ml FEV1 were associated with each mg/m3-yr of cumulative coal mine dust exposure, but were not statistically significant (p > 0.05). From the analysis of longitudinal change in spirometry from R1/R2 to Round 4 (R4), annual declines in FVC (-0.10 ml/yr per mg/m3-yr, p = 0.003) and FEV1 (-0.07 ml/yr per mg/m3-yr, p = 0.006) were associated with pre-R1/R2 exposure. Both the pattern and the magnitude of the exposure-response relationship were different for experienced versus new miners. Possible reasons for these contrasts include differences in cumulative exposure between the two groups and the healthy worker effect among experienced miners.

Coal↗
PubMed2006

Monochromatic ocular wave aberrations in young monkeys.

High-order monochromatic aberrations could potentially influence vision-dependent refractive development in a variety of ways. As a first step in understanding the effects of wave aberration on refractive development, we characterized the maturational changes that take place in the high-order aberrations of infant rhesus monkey eyes. Specifically, we compared the monochromatic wave aberrations of infant and adolescent animals and measured the longitudinal changes in the high-order aberrations of infant monkeys during the early period when emmetropization takes place. Our main findings were that (1) adolescent monkey eyes have excellent optical quality, exhibiting total RMS errors that were slightly better than those for adult human eyes that have the same numerical aperture and (2) shortly after birth, infant rhesus monkeys exhibited relatively larger magnitudes of high-order aberrations predominately spherical aberration, coma, and trefoil, which decreased rapidly to assume adolescent values by about 200 days of age. The results demonstrate that rhesus monkey eyes are a good model for studying the contribution of individual ocular components to the eye's overall aberration structure, the mechanisms responsible for the improvements in optical quality that occur during early ocular development, and the effects of high-order aberrations on ocular growth and emmetropization.

Accommodation, Ocular↗
PubMed2006

Brain metabolite concentrations and neurocognition during short-term recovery from alcohol dependence: Preliminary evidence of the effects of concurrent chronic cigarette smoking.

BACKGROUND: Longitudinal studies of brain tissue metabolite recovery in short-term abstinent alcoholics have primarily investigated the frontal lobes and cerebellum with variable results. Preliminary proton magnetic resonance spectroscopic imaging (1H MRSI) suggested that chronic cigarette smoking exacerbates alcohol-induced brain injury in 1-week abstinent alcoholics. However, the potential effects of chronic cigarette smoking on the recovery of alcohol-induced brain injury have not been studied. METHODS: Multislice short-echo time 1H MRSI was used to measure longitudinal changes in common brain metabolites in 25 recovering alcohol-dependent individuals (RA), retrospectively assigned to smoking (n = 14) and nonsmoking (n = 11) subgroups. Recovering alcohol-dependent individuals in longitudinal analyses were studied after approximately 7 and 34 days of abstinence from alcohol. In cross-sectional analyses, 36 RA (19 smokers, 17 nonsmokers) with approximately 34 days of sobriety were compared with 29 light drinkers (LD). Relationships between neurocognition and metabolite concentrations in abstinent RA were also examined. RESULTS: Over 1 month of abstinence from alcohol, RA, as a group, showed significant increases of regional N-acetylaspartate (NAA; marker of neuronal viability) and choline-containing compounds (Cho; marker of cell membrane synthesis/turnover) primarily in frontal and parietal lobes. These increases appeared to be driven by nonsmoking RA. Cross-sectional results indicate that metabolite levels in RA at 35 days of sobriety are not significantly different from those in LD in most regions, except for lower NAA and Cho in parietal WM and subcortical structures. However, metabolite levels at that time appear to be strongly modulated by smoking status. The patterns of metabolite-neurocognition relationships were different for nonsmoking and smoking RA. CONCLUSIONS: Within the first weeks of sobriety, regional brain NAA and Cho levels increased, but metabolite levels did not normalize in all brain regions after 35 days of sobriety. Neurobiologic recovery in RA appeared to be adversely affected by chronic smoking. Greater consideration of the effects of continued cigarette smoking on the neurobiologic and neurocognitive recovery of alcohol-dependent individuals is warranted.

Adult↗
PubMed2005

Left ventricular endocardial longitudinal and transverse changes during isovolumic contraction and relaxation: a challenge.

Left ventricular (LV) longitudinal and transverse geometric changes during isovolumic contraction and relaxation are still controversial. This confusion is compounded by traditional definitions of these phases of the cardiac cycle. High-resolution sonomicrometry studies might clarify these issues. Crystals were implanted in six sheep at the LV apex, fibrous trigones, lateral and posterior mitral annulus, base of the aortic right coronary sinus, anterior and septal endocardial wall, papillary muscle tips, and edge of the anterior and posterior mitral leaflets. Changes in distances were time related to LV and aortic pressures and to mitral valve opening. At the beginning of isovolumic contraction, while the mitral valve was still open, the LV endocardial transverse diameter started to shorten while the endocardial longitudinal diameter increased. During isovolumic relaxation, while the mitral valve was closed, LV transverse diameter started to increase while the longitudinal diameter continued to decrease. These findings are inconsistent with the classic definitions of the phases of the cardiac cycle.

Animals↗
PubMed1983

A 3-year longitudinal study of school-aged children's fundamental frequencies.

This report describes the longitudinal changes that took place in the average fundamental frequencies (fo) of 25 boys and girls over a 3-year period (means age range = 8:2-11:2). Results showed that developmental changes in the central tendency of fo can be detected over a 1-year period. For the group, the amount of decrease per 12-month interval averaged about 12 Hz, with a standard deviation of about 8 Hz. Cross-sectional observations of 7-11-year-old children's fundamental frequency characteristics do not reflect accurately the developmental course of fo, in large part because the between-subject standard deviations are larger than the age-related changes that occur in children's voices at this stage of development.

Age Factors↗
PubMed1998

Bone measurements in asymptomatic primary hyperparathyroidism.

A large proportion of patients with asymptomatic primary hyperparathyroidism (PHPT) have some degree of bone involvement which appears to be relatively greater for cortical than trabecular bone. However, the clinical meaning and pathophysiologic basis of this observation are unknown. In 77 postmenopausal women with asymptomatic PHPT, bone mineral density (BMD) was measured at the proximal and ultradistal forearm, the lumbar spine, the femoral neck, and Ward's triangle by dual-energy X-ray absorptiometry. The digitalized X-ray pictures of the nondominant hand were obtained from all patients and from 680 healthy postmenopausal women, to measure the outer (D) and inner (d) diameter of the second metacarpus. The cortical area per total area (CA/TA) and a bending breaking resistance index (D4-d4/D) were then calculated. In 29 of the patients not operated on and in 30 healthy pair-matched women, a second X-ray of the hand was obtained 5-12 years afterward. In patients with PHPT, the z score of CA/TA was significantly lower than zero [-0.97+/-0.99, standard deviation (SD)]. This is due to an enlargement of the inner diameter, despite a significant increase in the z score for the outer diameter. The z score of the DXA measurements was significantly lower than zero for the lumbar spine (-0.59+/-1.26), ultradistal radius (-1.03+/-0.91), proximal radius (-1.91+/-1.80), and Ward triangle (-1.81+/-1.07), but not for the femoral neck (-0.36+/-1.03). In subjects in whom two X-rays were obtained, per-decade endosteal resorption and periosteal apposition were statistically significant only in the PHPT patients. Both endosteal resorption and periosteal apposition were significantly greater in PHPT patients compared to healthy controls. The mean BBRI in PHPT patients was not different from that in controls, but the longitudinal changes were significantly greater than those observed in control subjects. Our radiogrammetry data may provide an original clue for understanding preferential cortical bone loss in PHPT patients. In cross-sectional and longitudinal studies, we have shown that in PHPT, both endosteal bone resorption and periosteal apposition are augmented. The former effect is predominant, which leads to significant diminution of cortical thickness. As a consequence of the enlargement of long bones, the areal BMD is somewhat underestimated, since the same amount of cortical bone is divided by a greater diameter. Furthermore, in term of mechanical properties, the increases in the cross-sectional area of appendicular bone segments might compensate in part for both the diminution of cortical thickness and a greater porosity of cortical bone.

Absorptiometry, Photon↗
PubMed1999

Postnatal change of renal artery blood flow velocity and its relationship with urine volume in very low birth weight infants during the first month of life.

Although the renal artery blood flow velocity has been investigated recently using the ultrasound Doppler method, little is known about the longitudinal change of renal artery blood flow velocity and its relationship with urine volume in very low birth weight infant. Thus, we measured renal artery blood flow velocities by means of the pulse Doppler method in 28 very low birth weight infants. Maximum, minimum, and mean blood flow velocities were determined at postnatal days 0, 1, 2, 3, 4, 5, 6, 13, 20, and 27. The resistance index was also calculated. The maximum and mean blood flow velocities increased gradually after birth, and were significantly higher at 13, 20, and 27 days after birth. The minimum blood flow velocity and the resistance index were relatively constant during the study period. The mean blood flow velocities were also analyzed for any correlation with urine volume. There was a poor correlation between urine volume (ml/kg/day) and mean blood flow velocity (cm/s) (Y = 2.38X + 57.4, Y: urine volume, X: mean blood flow velocity, n = 161, r = 0.338, P < 0.01). However, if the mean renal artery blood flow velocity was less than 10 cm/s, oliguria was observed in most cases. The measurement of the renal artery blood flow velocities appears to be useful in understanding the background condition of renal function in very low birth weight infants.

Aging↗
PubMed1997

Comparison of occlusal contacts with use of Hawley and clear overlay retainers.

Following orthodontic treatment, an increase in the number of occlusal contacts is usually desired during retention. In this study, Hawley and clear overlay orthodontic retainers were compared relative to changes in the number of occlusal contacts. Occlusal contacts were quantified in 30 orthodontic patients at debonding, at retainer delivery, and after 3 months of retention. The paired t-test was applied to evaluate longitudinal changes in the number of and intensity of contacts. Results show that with the Hawley retainer there was a significant increase in occlusal contacts on posterior teeth and no change on anterior teeth. With the clear overlay retainer there was no significant change in either posterior or anterior contacts during retention. The retentive capacities of the two retainers differ: the Hawley retainer allows relative vertical movement (settling) of the posterior teeth while the clear overlay retainer holds teeth in their debanding position.

Acrylic Resins↗
PubMed2001

[The health of students during their education].

Longitudinal changes of health and well-being during the course of studies at the university have been rarely studied in Germany so far. Therefore, data were analysed from a cohort of 166 students who took part in a baseline survey as freshmen at the beginning of their studies and in a follow-up after two years. The questionnaire assessed the frequency of symptoms and complaints, psycho-social and study-related sources of stress and health attitudes and perceptions. Longitudinal trends were studied based on variables identified by factor analysis. The results showed no changes in physical health indicators (complaints and self-rated health status), while the mental stressors with respect to study demands, study conditions and private situation showed significant increases. On the other hand, there were moderate increases observed in health awareness and physical activity of students from baseline to follow-up. We conclude that the increase in perceived mental stress indicates a vulnerability during the initial study. In addition, the positive developments regarding health awareness of students during studies should be supported by health promotion measures at the university.

Adolescent↗
PubMedDate not supplied

Effect of aging on cardiothoracic ratio in women: a longitudinal study.

BACKGROUND: The effect of aging on the components of the cardiothoracic ratio (CTR) in the chest roentgenogram in women remains obscure. There have been only a few reported studies that have investigated longitudinal changes of the CTR in women. OBJECTIVE: To determine whether there is an effect of aging on the CTR in women. METHODS: The study population consisted of 110 women who attended an annual health screening and underwent chest roentgenography both in 1981 and 1990 in a mountain village in Japan. We used the data obtained from an annual health screening in order to determine thoracic diameter (TD), cardiac diameter (CD), and lung height (LH) and then calculated the CTR. We analyzed CTR, TD, CD, and LH on the basis of the age of the participants. RESULTS: In the cross-sectional analysis of the groups stratified by age in 1981, mean CD and CTR increased, and TD decreased in the advanced-age group. The percentage of radiographic cardiomegaly (CTR >50%) strikingly increased in the advanced-age group. In the longitudinal analysis between 1981 and 1990, the mean CD increased, and the mean TD decreased significantly. The mean CTR increased by 2.0% (95% CI 1. 2-2.8%). The changes of the CTR in 9 years were positively correlated with those of CD and negatively correlated with those of TD and LH. The longitudinal data generally accorded with the cross-sectional data, except LH. CONCLUSIONS: The CTR in women increases with aging as a result of the increase in CD, except in the case of advanced old age, and the decrease in TD. LH could be another major factor that has an influence on CTR. Caution should be exercised to avoid overestimating CTR when LH changes. The classical upper limit of 50% for CTR in our adopted method should not be applied to elderly women because of the possibility that changes with normal aging are misclassified as abnormal findings.

Adult↗
PubMed2005

Changes in accessibility and usability in housing: an exploration of the housing adaptation process.

The purpose of a housing adaptation is to enhance daily activities and to improve housing accessibility and usability by removing physical barriers in the home. The aim of this study was to investigate longitudinal changes in housing accessibility among clients receiving grants for housing adaptations. Baseline assessments were administered one month before the housing adaptation, with the first follow-up after two to three months, and the second follow-up after eight to nine months. The Housing Enabler and the Usability in My Home instruments were used to collect data from 131 consecutively enrolled clients living in general housing. Accessibility and usability improved significantly, the number of physical environmental barriers decreased and dependence on mobility devices increased, but at different times along the process. The results indicate the complexity of the housing adaptation process and the need to consider person-environment interactions over time. The methodology seems useful for quality development of assessment, intervention and evaluation processes in housing adaptations performed by occupational therapists.

Activities of Daily Living↗
PubMed2005

Externalizing behaviors as predictors of substance initiation trajectories among rural adolescents.

PURPOSE: The purpose of the current study was to investigate the influence of externalizing behaviors on substance initiation trajectories among rural adolescents over a 42-month period. METHODS: Data were obtained from 198 rural adolescents (105 boys, 93 girls) who were participating in a longitudinal study. At the baseline assessment, subjects were on average 12.3 years of age. RESULTS: Controlling for gender, higher baseline levels of externalizing were associated with a greater number of substances initiated over time. The initiation trajectory was curvilinear. Girls, compared with boys, reported a lower number of substances initiated at baseline, a greater linear growth trajectory, and a deceleration of growth over time. CONCLUSIONS: The influence of adolescent externalizing behaviors on baseline levels and growth trajectories of substance initiation and the utility of latent growth curve modeling in the study of longitudinal change are discussed.

Adolescent↗
PubMed1992

Longitudinal study of dietary intakes and plasma lipids in healthy elderly men and women.

Dietary intakes and blood lipid concentrations were assessed in elderly men (n = 65) and women (n = 92) from 1980 through 1989. Mean age in 1980 was 70 y (range 60-84 y). Health and socioeconomic status was above that found in the general US elderly population. Cross-sectional and longitudinal changes in variables were determined by using least-squares linear regression. No significant cross-sectional differences in energy (kJ/kg), protein (g/kg), total fat, and carbohydrate intake with age was noted. Significant longitudinal decreases in total fat, saturated and polyunsaturated fatty acids, and cholesterol intakes were noted in both men and women. Significant decreases in total, HDL, and LDL plasma cholesterol concentrations were noted over time in both men and women. Ratios of both total and LDL cholesterol to HDL cholesterol increased over time. The decrease in total fat and cholesterol intakes were significantly correlated with the decrease in total plasma cholesterol.

Aged↗
PubMed2002

Annual lung function changes in young patients with chronic lung disease.

Reference equations for ventilatory function that use different statistical models may introduce artifacts that affect the estimated change of lung function during growth in young subjects. The effect of differently modelled reference equations on the estimated annual change of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) in young patients with chronic lung disease was assessed. Four frequently used reference equations were used to describe the longitudinal changes of FEV1 and FVC in 52 patients (23 females) with cystic fibrosis (CF) during a mean follow-up of 3.9 yrs. Choice of reference equations directly affected value and, most importantly, estimated annual change of FVC and FEV1. Mean+/-SD annual change of FEV1 varied from 2.2+/-6.2 to -2.2+/-3.6% of predicted. For two reference equations the estimated individual changes of FEV1 and FVC in CF were positively correlated with mean individual age. This probably reflects underestimation of deteriorating lung function. Variability of annual change was independent of age only when reference equations that were designed to accurately predict lung function during the pubertal growth spurt were used. These findings have implications for patient care and clinical research.

Adolescent↗
PubMed1997

Ten year trends in the dietary habits of Danish men and women. Cohort and cross-sectional data.

OBJECTIVE: To describe 10 year trends and individual changes in food habits of Danish men and women in relation to dietary recommendations using data from both a cohort and a repeated cross-sectional study, and to examine whether the two sampling methods give similar results. DESIGN: Baseline data were collected in 1982-1984 and respectively repeated measurements for cohort and cross-sectional changes in food habits. SETTING: The County of Copenhagen, Denmark. SUBJECTS: Men and women aged 30-70y in 1982-1984, 1986-1988 and 1992-1994. The trend analyses included 3785 subjects for cohort and 7316 for cross-sectional study, respectively. Longitudinal changes were studied among 2430 individuals with food data from all three examinations. METHODS: Food intakes were estimated using a short food frequency questionnaire. RESULTS: During the study period both men and women reported a decreased intake frequency of animal and vegetable fats, milk, eggs, meat products, white bread and potatoes, while they had increased intakes of low-fat margarine, fruit, raw vegetables, coarse breads, oatmeal, pasta, rice, cakes and candy. In both men and women the decrease in the consumption frequency of, white bread and potatoes, and the increase in pasta, and candy, were higher in the younger than in the older age group. In contrast, the increased consumption frequency of coarse breads, and oatmeal were most pronounced in the older age groups. For most foods the cohort and the repeated cross-sectional surveys gave similar results. CONCLUSIONS: From 1982 through 1994 the food habits of middle-aged Danish men and women changed in the direction of a more healthy diet as recommended by health authorities. With the limitation of a possible reporting bias both the cohort and repeated cross-sectional study designs may be used for monitoring changes in food intake.

Adult↗
PubMed1992

Osteophytosis of the knee: association with changes in weight-bearing exercise.

Osteoarthritis has been held to result from wear and tear. We addressed this hypothesis by analysis of anteroposterior radiographs of the knees of 51 subjects with mean age of 60 years who regularly practiced weight-bearing exercise. Radiographs were assessed for longitudinal changes in spur formation over a two-year period. The results showed a negative association between changes in weight-bearing exercise and changes in the rate of spur development in both males and females. The findings suggest that increasing repetitive impulse loading in the form of regular painless weight-bearing activity does not promote osteophytosis (or perhaps degenerative disease) in knee joints.

Aged↗