Age Trend (age + trend)

Distribution by Scientific Domains


Selected Abstracts


Age Trends in Femur Stresses From a Simulated Fall on the Hip Among Men and Women: Evidence of Homeostatic Adaptation Underlying the Decline in Hip BMD

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2006
Thomas J Beck ScD
Abstract Age trends in proximal femur stresses were evaluated by simulating a fall on the greater trochanter using femur geometry from hip DXA scans of 5334 white men and women in the NHANES III survey. Expansion of femur outer diameter seems to counter net bone loss so that stresses remain similar across age groups, but stresses are higher in older women than in older men. Introduction: The age decline in hip BMD is caused by both bone loss and expansion of outer diameter that increases the region size over which mass is measured in a DXA scan. Because expansion has an opposing effect on structural strength, it may be a homeostatic adaptation to net bone loss to ensure that load stresses are kept within a narrow range. Materials and Methods: Age trends in femur stresses were evaluated with an engineering beam simulation of a fall on the greater trochanter. Hip geometry was extracted from hip DXA scans using the Hip Structure Analysis (HSA) software on 2613 non-Hispanic white men and 2721 women from the third National Health and Nutrition Examination Survey (NHANES III). Using body weight as load, stresses were computed on the inferior-medial and superior-lateral femur neck at its narrowest point and the medial and lateral shaft 2 cm distal to the midpoint of the lesser trochanter. Stresses and the underlying geometries in men and women >50 years oaf age were compared with those 20,49 years of age. Results: Compared with men <50 years of age, stresses in older men were 6% lower on both surfaces of the shaft, 4% lower on the inferior-medial neck, and not different on the superior-lateral neck. In women >50 years of age, stresses on the proximal shaft and inferior-medial neck remained within 3% of young values but were 13% greater on the superior-lateral neck. Neck stresses in young women were lower on the superior-lateral than the inferior-medial neck, but lateral stress increased to the level on the medial surface in older women. Stresses were higher in women than in men, with a greater gender difference in those >50 years of age. Conclusions: We conclude that femur expansion has a homeostatic effect in men and women that opposes bone loss so that stresses change little with age. Because expansion preserves stresses with progressively less bone mass, the process may reduce structural stability in the femoral neck under fall conditions, especially in the elderly female. [source]


Identifying High Risk Groups and Quantifying Absolute Risk of Cancer After Kidney Transplantation: A Cohort Study of 15 183 Recipients

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 9 2007
A. C. Webster
Transplant recipients have increased cancer risk, but data on risk variation across different patient groups are sparse. Rates and standardized rate ratios (SRR) of cancer (all sites, excluding nonmelanocytic skin and lip cancer) compared to the general population were calculated, using Australia and New Zealand Dialysis and Transplant Registry data. Within the transplant population, risk factors were identified (hazard ratios: HR; 95% CI) and absolute risk estimated for recipient groups. A total of 1642 (10.8%) of 15 183 recipients developed cancer. Risk was inversely related to age (SRR 15,30 children, 2 if >65 years). Females aged 25,29 had rates equivalent to women aged 55,59 from the general population. Age trend for lymphoma, colorectal and breast risk was similar; melanoma showed less variability across ages, prostate showed no risk increase. Within the transplanted population, risk was affected by age differently for each sex (p = 0.007), elevated by prior malignancy (HR 1.40; 1.03,1.89), white race (HR 1.36; 1.12,1.89), but reduced by diabetic end-stage kidney disease (ESKD) (HR 0.67; 0.50,0.89). Cancer rates in kidney recipients are similar to nontransplanted people 20,30 years older, but absolute risk differs across patient groups. Men aged 45,54 surviving 10 years have cancer risks varying from 1 in 13 (non-white, no prior cancer, diabetic ESKD) to 1 in 5 (white, prior cancer, other ESKD). [source]


Age Trends in Femur Stresses From a Simulated Fall on the Hip Among Men and Women: Evidence of Homeostatic Adaptation Underlying the Decline in Hip BMD

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2006
Thomas J Beck ScD
Abstract Age trends in proximal femur stresses were evaluated by simulating a fall on the greater trochanter using femur geometry from hip DXA scans of 5334 white men and women in the NHANES III survey. Expansion of femur outer diameter seems to counter net bone loss so that stresses remain similar across age groups, but stresses are higher in older women than in older men. Introduction: The age decline in hip BMD is caused by both bone loss and expansion of outer diameter that increases the region size over which mass is measured in a DXA scan. Because expansion has an opposing effect on structural strength, it may be a homeostatic adaptation to net bone loss to ensure that load stresses are kept within a narrow range. Materials and Methods: Age trends in femur stresses were evaluated with an engineering beam simulation of a fall on the greater trochanter. Hip geometry was extracted from hip DXA scans using the Hip Structure Analysis (HSA) software on 2613 non-Hispanic white men and 2721 women from the third National Health and Nutrition Examination Survey (NHANES III). Using body weight as load, stresses were computed on the inferior-medial and superior-lateral femur neck at its narrowest point and the medial and lateral shaft 2 cm distal to the midpoint of the lesser trochanter. Stresses and the underlying geometries in men and women >50 years oaf age were compared with those 20,49 years of age. Results: Compared with men <50 years of age, stresses in older men were 6% lower on both surfaces of the shaft, 4% lower on the inferior-medial neck, and not different on the superior-lateral neck. In women >50 years of age, stresses on the proximal shaft and inferior-medial neck remained within 3% of young values but were 13% greater on the superior-lateral neck. Neck stresses in young women were lower on the superior-lateral than the inferior-medial neck, but lateral stress increased to the level on the medial surface in older women. Stresses were higher in women than in men, with a greater gender difference in those >50 years of age. Conclusions: We conclude that femur expansion has a homeostatic effect in men and women that opposes bone loss so that stresses change little with age. Because expansion preserves stresses with progressively less bone mass, the process may reduce structural stability in the femoral neck under fall conditions, especially in the elderly female. [source]


Role of Pap Test terminology and age in the detection of carcinoma invasive and carcinoma in situ in medically underserved California women

DIAGNOSTIC CYTOPATHOLOGY, Issue 4 2004
Lydia P. Howell M.D.
Abstract Our goals were to evaluate Pap Test findings classified by the Bethesda system, and follow up biopsies from participants in the California Breast and Cervical Cancer Control Program (Ca-BCCCP) for: 1) correlation in the detection of carcinoma in situ (CIS) and carcinoma invasive (CI), and 2) age-related trends, with discussion in the context of the 2001 ASCCP Management Guidelines. Women (n = 52,339) who had their initial screening Pap Tests with Ca-BCCCP between January 1995,December 1999 were followed for diagnostic services through December 2000. Descriptive and analytical methods were used in the analysis. Of the Pap results, 81.9% were negative, 10.6% showed infection, 4.7% showed an epithelial abnormality as defined by the Bethesda system (atypical squamous cells of undertermined significance (ASCUS), low-grade squamous intraepithelial lesion (LSIL), or high-grade squamous intraepithelial lesion (HSIL)), 0.1% showed squamous-cell cancer (SCC), and 2.7% showed other or unsatisfactory. Subsequent to the initial Pap Test, follow-up results of carcinoma in situ (CIS) and carcinoma invasive (CI) accounted for 0.36% and 0.05% of the population, respectively. Among HSIL Pap Tests (n = 285), 40.7% had follow-up showing CIS. Among SCC Pap Tests, 17.9% had follow-up results of CIS and 28.6% CI. Of the 191 patients with CIS as a follow-up finding, the initial Pap smear showed: HSIL 60.7%, SCC 2.6%, LSIL 10.5%, ASCUS 13.6%, and negative or infection 9.9%. Of the 27 patients with CI, the initial Pap Test showed: HSIL 40.7%, SCC 29.6%, LSIL 7.4%, ASCUS 7.4%, and negative or infection 11.1%. Pap diagnoses of other or unsatisfactory accounted for 2.6% of the Pap results from patients with CIS and 3.7% of Pap results from patients with CI. Except for LSIL, there was an increasing age trend in the number of cases in each of Pap results, with the exception of age 65+ yr. However, the ratio of LSIL and ASCUS to negative cases decreased with age. (P < 0.0001 and 0.0293, respectively). HSIL Pap results indicate a reasonably high probability of CIS and CI. However, approximately 1/3 of patients with CIS and 1/4 of patients with CI presented with Pap diagnoses of less severity than HSIL. When a negative Pap Test result is chosen as reference group, there is a negative age trend for LSIL and ASCUS, and no age trend for other results. These findings all have important implications in the design of follow-up strategies, and support the 2001 ASCCP Consensus Guidelines for the Management of Women with Cervical Abnormalities. Diagn. Cytopathol. 2004;30:227,234. 2004 Wiley-Liss, Inc. [source]


The NOAO Fundamental Plane Survey , III.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2006
Variations in the stellar populations of red-sequence galaxies from the cluster core to the virial radius
ABSTRACT We analyse absorption line-strength indices for ,3000 red-sequence galaxies in 94 nearby clusters to investigate systematic variations of their stellar content with location in the host cluster. The data are drawn from the National Optical Astronomy Observatory (NOAO) Fundamental Plane Survey. Our adopted method is a generalization of that introduced by Nelan et al. to determine the global age,mass and metallicity,mass relations from the same survey. We find strong evidence for a change in galaxy properties, at fixed mass, over a range from the cluster centre to the virial radius, R200. For example, red-sequence galaxies further out in the clusters have weaker Mgb5177 (at ,8, significance) and stronger H, and H, absorption (,3,, ,4,) than galaxies of the same velocity dispersion in the cluster cores. The Fe5270 and Fe5335 indices show only very weak trends with radius. Using a total of 12 indices, the pattern of cluster-centric gradients is considered in light of their different dependences on stellar age and chemical composition. The measured gradients for all 12 indices can be reproduced by a model in which red-sequence galaxies at ,1 R200 have on average younger ages (by 15 4 per cent) and lower ,-element abundance ratios (by 10 2 per cent) than galaxies of the same velocity dispersion but located near the cluster centres. For the total metallicity, Z/H, no significant gradient is found (2 3 per cent larger at R200 than in the cores). There are hints that the age trend may be stronger for galaxies of lower mass and/or for galaxies with more discy morphology. We show, however, that the trends cannot be driven primarily by changes in the morphological mix as a function of radius. The cluster-centric age and [,/Fe] gradients are in the sense expected if galaxies in the cluster core were accreted at an earlier epoch than those at larger radii, and if this earlier accretion contributed to an earlier cessation of star formation. The size of the observed age trend is comparable to predictions from semi-analytic models of hierarchical galaxy formation. [source]


Structural Trends in the Aging Femoral Neck and Proximal Shaft: Analysis of the Third National Health and Nutrition Examination Survey Dual-Energy X-Ray Absorptiometry Data,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2000
Thomas J. Beck
Abstract Hip scans of U.S. adults aged 20,99 years acquired in the Third National Health and Nutrition Examination Survey (NHANES III) using dual-energy X-ray absorptiometry (DXA) were analyzed with a structural analysis program. The program analyzes narrow (3 mm wide) regions at specific locations across the proximal femur to measure bone mineral density (BMD) as well as cross-sectional areas (CSAs), cross-sectional moments of inertia (CSMI), section moduli, subperiosteal widths, and estimated mean cortical thickness. Measurements are reported here on a non-Hispanic white subgroup of 2719 men and 2904 women for a cortical region across the proximal shaft 2 cm distal to the lesser trochanter and a mixed cortical/trabecular region across the narrowest point of the femoral neck. Apparent age trends in BMD and section modulus were studied for both regions by sex after correction for body weight. The BMD decline with age in the narrow neck was similar to that seen in the Hologic neck region; BMD in the shaft also declined, although at a slower rate. A different pattern was seen for section modulus; furthermore, this pattern depended on sex. Specifically, the section modulus at both the narrow neck and the shaft regions remains nearly constant until the fifth decade in females and then declined at a slower rate than BMD. In males, the narrow neck section modulus declined modestly until the fifth decade and then remained nearly constant whereas the shaft section modulus was static until the fifth decade and then increased steadily. The apparent mechanism for the discord between BMD and section modulus is a linear expansion in subperiosteal diameter in both sexes and in both regions, which tends to mechanically offset net loss of medullary bone mass. These results suggest that aging loss of bone mass in the hip does not necessarily mean reduced mechanical strength. Femoral neck section moduli in the elderly are on the average within 14% of young values in females and within 6% in males. [source]


Effect of plant variety, plant age and photoperiod on glandular pubescence and host-plant resistance to potato moth (Phthorimaea operculella) in Lycopersicon spp.

ANNALS OF APPLIED BIOLOGY, Issue 2 2001
G M GURR
Summary The effect of plant age and daylength on glandular pubescence was determined for two lines of tomato derived from Lycopersicon hirsutum (BTN 979 and LA 1777A) and a variety of L. esculentum (N 91-1-1-1-1). Densities of type I, IV, VI and VII glandular trichomes were lowest in N 91-1-1-1-1 and, over all varieties, were more dense on plants aged greater than 6 wk. Daylength interacted with variety to significantly affect densities of type VII trichomes only. Host-plant resistance to Phthorimaea operculella was determined in preliminary tests using insects cultured from founders from a potato crop and in confirmatory tests using (less readily available) insects recovered from foliage of a tomato crop. Mortality of ex-potato neonates on LA 1777 A and BTN 979 foliage was higher 18 h after placement than for N 91-1-1-1-1, with no effect of day length or plant age. Mortality for ex-tomato neonates followed a similar trend. Ten days later, two-thirds of ex-tomato larvae had established mines on N 91-1-1-1-1 but fewer (16.7%) were live on other varieties. Stepwise multiple regression using variety as the sole factor was significant (P<0.001) in accounting for 61.4% of the variation in ex-tomato larval survival but addition of other factors to the regression model was not significant. BTN 979 supported fewer, smaller adults to develop than did N 91-1-1-1-1, whilst no adults developed on LA 1777 A. In a non-choice test using ex-potato adults, significantly more eggs were laid on N 91-1-1-1-1 than on L. hirsutum varieties and 9-wk-old plants were preferred over plants three weeks older or younger. The same variety and plant age trends were evident in a free-choice test using ex-tomato adults. [source]