Why are there Different Age Related Trends for Different Chemicals?

Persistent organic pollutants (POPs) such as dioxins, PCBs, persistent organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) as well as perfluorinated compounds (PFCs) and triclosan are ubiquitous in the human population. In Australia, we have pooled and subsequently analysed over 10 000 human serum samples for the determination of these chemicals by age group (0–0.5; 0.6–1; 1.1–1.5; 1.6–2; 2.1–2.5; 2.6–3; 3.1–3.5; 3.6–4; 4.1–6; 6.1–9; 9.1–12; 12.1–15; 16–30; 31–45; 46–60 and >60 years) and gender. The results of this analysis were then used to assess the trends of these different chemicals as a function of age, gender and to a lesser extent region. Our data demonstrate clear chemical specific age trends. In particular we demonstrate that for the traditional POPs there is an increase in body burden with age whereas the opposite is true for chemicals such as PBDEs. For PFCs we find chemical specific age trends that vary from compound to compound. For triclosan we show that no apparent age trend is observable. The results of the study and its implications to the collection and archiving of samples for retrospective analysis are discussed.

Automated diagnosis of Age-related Macular Degeneration using greyscale features from digital fundus images

Age-related Macular Degeneration (AMD) is one of the major causes of vision loss and blindness in ageing population. Currently, there is no cure for AMD, however early detection and subsequent treatment may prevent the severe vision loss or slow the progression of the disease. AMD can be classified into two types: dry and wet AMDs. The people with macular degeneration are mostly affected by dry AMD. Early symptoms of AMD are formation of drusen and yellow pigmentation. These lesions are identified by manual inspection of fundus images by the ophthalmologists. It is a time consuming, tiresome process, and hence an automated diagnosis of AMD screening tool can aid clinicians in their diagnosis significantly. This study proposes an automated dry AMD detection system using various entropies (Shannon, Kapur, Renyi and Yager), Higher Order Spectra (HOS) bispectra features, Fractional Dimension (FD), and Gabor wavelet features extracted from greyscale fundus images. The features are ranked using t-test, Kullback–Lieber Divergence (KLD), Chernoff Bound and Bhattacharyya Distance (CBBD), Receiver Operating Characteristics (ROC) curve-based and Wilcoxon ranking methods in order to select optimum features and classified into normal and AMD classes using Naive Bayes (NB), k-Nearest Neighbour (k-NN), Probabilistic Neural Network (PNN), Decision Tree (DT) and Support Vector Machine (SVM) classifiers. The performance of the proposed system is evaluated using private (Kasturba Medical Hospital, Manipal, India), Automated Retinal Image Analysis (ARIA) and STructured Analysis of the Retina (STARE) datasets. The proposed system yielded the highest average classification accuracies of 90.19%, 95.07% and 95% with 42, 54 and 38 optimal ranked features using SVM classifier for private, ARIA and STARE datasets respectively. This automated AMD detection system can be used for mass fundus image screening and aid clinicians by making better use of their expertise on selected images that require further examination.

Decision support system for age-related macular degeneration using discrete wavelet transform

Age-related macular degeneration (AMD) affects the central vision and subsequently may lead to visual loss in people over 60 years of age. There is no permanent cure for AMD, but early detection and successive treatment may improve the visual acuity. AMD is mainly classified into dry and wet type; however, dry AMD is more common in aging population. AMD is characterized by drusen, yellow pigmentation, and neovascularization. These lesions are examined through visual inspection of retinal fundus images by ophthalmologists. It is laborious, time-consuming, and resource-intensive. Hence, in this study, we have proposed an automated AMD detection system using discrete wavelet transform (DWT) and feature ranking strategies. The first four-order statistical moments (mean, variance, skewness, and kurtosis), energy, entropy, and Gini index-based features are extracted from DWT coefficients. We have used five (t test, Kullback–Lieber Divergence (KLD), Chernoff Bound and Bhattacharyya Distance, receiver operating characteristics curve-based, and Wilcoxon) feature ranking strategies to identify optimal feature set. A set of supervised classifiers namely support vector machine (SVM), decision tree, k -nearest neighbor ( k -NN), Naive Bayes, and probabilistic neural network were used to evaluate the highest performance measure using minimum number of features in classifying normal and dry AMD classes. The proposed framework obtained an average accuracy of 93.70 %, sensitivity of 91.11 %, and specificity of 96.30 % using KLD ranking and SVM classifier. We have also formulated an AMD Risk Index using selected features to classify the normal and dry AMD classes using one number. The proposed system can be used to assist the clinicians and also for mass AMD screening programs.

Obesity and hypertension have differing oxidant handling molecular pathways in age-related chronic kidney disease

Chronic kidney disease (CKD) in ageing is a burden on health systems worldwide. Rat models of age-related CKD linked with obesity and hypertension were used to investigate alterations in oxidant handling and energy metabolism to identify gene targets or markers for age-related CKD. Young adult (3 months) and old (21–24 months) spontaneously-hypertensive (SHR), normotensive Wistar-Kyoto (WKY) and Wistar rats (normotensive, obese in ageing) were compared for renal functional and physiological parameters, renal fibrosis and inflammation, oxidative stress (hemeoxygenase-1/HO-1), apoptosis and cell injury (including Bax:Bcl-2), phosphorylated and non-phosphorylated forms of oxidant and energy sensing proteins (p66Shc, AMPK), signal transduction proteins (ERK1/2, PKB), and transcription factors (NF-κB, FoxO1). All old rats were normoglycemic. Renal fibrosis, tubular epithelial apoptosis, interstitial macrophages and myofibroblasts (all p < 0.05), p66Shc/phospho-p66 (p < 0.05), Bax/Bcl-2 ratio (p < 0.05) and NF-κB expression (p < 0.01) were highest in old obese Wistars. Expression of phospho-FoxO/FoxO was elevated in old Wistars (p < 0.001) and WKYs (p < 0.01). SHRs had high levels in young and old rats. Expression of PKB, phospho-PKB, ERK1/2 and phospho-ERK1/2 were significantly elevated in all aged animals. These results suggest that obesity and hypertension have differing oxidant handling and signalling pathways that act in the pathogenesis of age-related CKD

Age related differences in the validity of the OMNI perceived exertion scale during lifestyle activities

PURPOSE The OMNI Perceived Exertion Scale was developed for children to report perceived effort while performing physical activity; however no studies have formally examined age-related differences in validity. This study evaluated the validity of the OMNI-RPE in four age groups performing a range of lifestyle activities. METHODS 206 participants were stratified into four age groups: 6-8 years (n = 42), 9-10 years (n = 46), 11-12 years (n = 47), and 13-15 years (n = 71). Heart rate and VO2 were measured during 11 activity trials ranging in intensity from sedentary to vigorous. After each trial, participants reported effort from the OMNI walk/run scale. Concurrent validity was assessed by calculating within-subject correlations between OMNI ratings and the two physiological indices. RESULTS The average correlation between OMNI ratings and VO2 was 0.67, 0.77, 0.85 and 0.87 for the 6-8, 9-10, 11-12 and 13-15 y age groups, respectively. CONCLUSION The OMNI RPE scale demonstrated fair to good evidence of validity across a range of lifestyle activities among 6-15 year old children. The validity of the scale appears to be developmentally related with RPE reports closely reflecting physiological responses among children older than 8 years.

Age-related changes in perception of movement in driving scenes

Purpose Age-related changes in motion sensitivity have been found to relate to reductions in various indices of driving performance and safety. The aim of this study was to investigate the basis of this relationship in terms of determining which aspects of motion perception are most relevant to driving. Methods Participants included 61 regular drivers (age range 22–87 years). Visual performance was measured binocularly. Measures included visual acuity, contrast sensitivity and motion sensitivity assessed using four different approaches: (1) threshold minimum drift rate for a drifting Gabor patch, (2) Dmin from a random dot display, (3) threshold coherence from a random dot display, and (4) threshold drift rate for a second-order (contrast modulated) sinusoidal grating. Participants then completed the Hazard Perception Test (HPT) in which they were required to identify moving hazards in videos of real driving scenes, and also a Direction of Heading task (DOH) in which they identified deviations from normal lane keeping in brief videos of driving filmed from the interior of a vehicle. Results In bivariate correlation analyses, all motion sensitivity measures significantly declined with age. Motion coherence thresholds, and minimum drift rate threshold for the first-order stimulus (Gabor patch) both significantly predicted HPT performance even after controlling for age, visual acuity and contrast sensitivity. Bootstrap mediation analysis showed that individual differences in DOH accuracy partly explained these relationships, where those individuals with poorer motion sensitivity on the coherence and Gabor tests showed decreased ability to perceive deviations in motion in the driving videos, which related in turn to their ability to detect the moving hazards. Conclusions The ability to detect subtle movements in the driving environment (as determined by the DOH task) may be an important contributor to effective hazard perception, and is associated with age, and an individuals' performance on tests of motion sensitivity. The locus of the processing deficits appears to lie in first-order, rather than second-order motion pathways.

Age-related changes to adenosine in rat coronary resistance vessels

1. The vasodilator effects of adenosine receptor agonists, isoprenaline and histamine were examined in perfused heart preparations from young (4–6 weeks) and mature (12–20 weeks) rats. 2. Adenosine induced a biphasic concentration-dependent decrease in KCl (35 mM) raised coronary perfusion pressure in hearts from young and mature rats, suggesting the presence of both high- and low-affinity sites for adenosine receptors in the two age groups tested. In heart preparations from mature rats, vasodilator responses to adenosine were significantly reduced compared with responses observed in young rats. 3. Responses to 5′-N-ethylcarboxamidoadenosine (NECA) and 2-p-(2-carboxyethyl)phenethylamino-5′-N-ethylcarboxamidoadenosine hydrochloride (CGS-21680) were reduced in preparations from mature rats, whereas the vasodilator actions of N6-cyclopentyladenosine (CPA) and N6-2-(4-aminophenyl)ethyladenosine (APNEA) did not change with age. 4. The results presented in this study suggest that several adenosine receptor subtypes mediate vasodilator responses in the coronary circulation of the rat and that a reduction in response to adenosine with age may be due to changes in the high-affinity receptor site.

Melanopsin mediated post-illumination pupil response in early age-related macular degeneration

Purpose To determine whether melanopsin expressing intrinsically photosensitive Retinal Ganglion Cell (ipRGC) inputs to the pupil light reflex (PLR) are affected in early age-related macular degeneration (AMD). Methods The PLR was measured in 40 participants (20 early AMD and 20 age-matched controls) using a custom-built Maxwellian-view pupillometer. Sinusoidal stimuli (0.5 Hz, 11.9 s duration, 35.6° diameter) were presented to the study eye and the consensual pupil response was measured for stimuli with high melanopsin excitation (464nm; blue) and with low melanopsin excitation (638 nm; red) that biased activation to the outer retina. Two melanopsin PLR metrics were quantified: the Phase Amplitude Percentage (PAP) during the sinusoidal stimulus presentation and the Post-Illumination Pupil Response (PIPR). The PLR during stimulus presentation was analyzed using latency to constriction, transient pupil response and maximum pupil constriction metrics. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curves. Results The blue PIPR was significantly less sustained in the early AMD group (p<0.001). The red PIPR was not significantly different between groups (p>0.05). The PAP and blue stimulus constriction amplitude were significantly lower in the early AMD group (p < 0.05). There was no significant difference between groups in the latency or transient amplitude for both stimuli (p>0.05). ROC analysis showed excellent diagnostic accuracy for the blue PIPR metrics (AUC>0.9). Conclusions This is the initial report that the melanopsin controlled PIPR is dysfunctional in early AMD. The non-invasive, objective measurement of the ipRGC controlled PIPR has excellent diagnostic accuracy for early AMD.

Melanopsin ganglion cell function in early age-related macular degeneration

Purpose Melanopsin-expressing retinal ganglion cells (mRGCs) have non-image forming functions including mediation of the pupil light reflex (PLR). There is limited knowledge about mRGC function in retinal disease. Initial retinal changes in age-related macular degeneration (AMD) occur in the paracentral region where mRGCs have their highest density, making them vulnerable during disease onset. In this cross-sectional clinical study, we measured the PLR to determine if mRGC function is altered in early stages of macular degeneration. Methods Pupil responses were measured in 8 early AMD patients (AREDS 2001 classification; mean age 72.6 ± 7.2 years, 5M, and 3F) and 12 healthy control participants (mean age 66.6 ± 6.1 years, 8M and 4F) using a custom-built Maxwellian-view pupillometer. Stimuli were 0.5 Hz sinewaves (10 s duration, 35.6° diameter) of short wavelength light (464nm, blue; retinal irradiance = 14.5 log quanta.cm-2.s-1) to produce high melanopsin excitation and of long wavelength light (638nm, red; retinal irradiance = 14.9 log quanta.cm-2.s-1), to bias activation to outer retina and provide a control. Baseline pupil diameter was determined during a 10 s pre-stimulus period. The post illumination pupil response (PIPR) was recorded for 40 s. The 6 s PIPR and maximum pupil constriction were expressed as percentage baseline (M ± SD). Results The blue PIPR was significantly less sustained (p<0.01) in the early AMD group (75.49 ± 7.88%) than the control group (58.28 ± 9.05%). The red PIPR was not significantly different (p>0.05) between the early AMD (84.79 ± 4.03%) and control groups (82.01 ± 5.86%). Maximum constriction amplitude in the early AMD group for blue (43.67 ± 6.35%) and red (48.64 ± 6.49%) stimuli were not significantly different to the control group for blue (39.94 ± 3.66%) and red (44.98 ± 3.15%) stimuli (p>0.05). Conclusions These results are suggestive of inner retinal mRGC deficits in early AMD. This non-invasive, objective measure of pupil responses may provide a new method for quantifying mRGC function and monitoring AMD progression.

Age-related alterations of immunoreactive pancreatic cationic trypsinogen in sera from cystic fibrosis patients with and without pancreatic insufficiency

Serum immunoreactive cationic trypsinogen levels were determined in 99 control subjects and 381 cystic fibrosis (CF) patients. To evaluate the status of the exocrine pancreas all CF patients had previously undergone fecal fat balance studies and/or pancreatic stimulation tests. Three hundred fourteen CF patients had fat malabsorption and/or had inadequate pancreatic enzyme secretion (pancreatic insufficiency) requiring oral pancreatic enzyme supplements with meals. Sixty-seven CF patients did not have fat malabsorption and/or had adequate enzyme secretion (pancreatic sufficiency) and were not receiving pancreatic enzyme supplements with meals. Mean serum trypsinogen in 99 control subjects was 31.4 ± 14.8 /µg/hter (± 2 SD) and levels did not vary with age or sex. In CF infants (< 2 yr) with pancreatic insufficiency, mean serum trypsinogen was significantly above the non-CF values (p < 0.001). Ninety-one percent of the CF infants had elevated levels. Serum trypsinogen values in the pancreatic insuffi ient group declined steeply up to 5 years, reaching subnormal values by age 6. An equation was developed which described these age-related changes very accurately. Only six CF patients with pancreatic insufficiency had serum trypsinogen levels above the 95% confidence limits of this equation. In contrast, there was no age related decline in serum trypsinogen among the CF group with pancreatic sufficiency. Under 7 yr, serum trypsinogen failed to distinguish the two groups. In those over 7 yr of age, however, serum trypsinogen was significantly higher than the CF group with pancreatic insufficiency (p < 0.001), and 93% had values within or above the control range. In conclusion, serum trypsinogen appears to be a useful screening test for CF in infancy. Between 2 and 7 yr of age this test is of little diagnostic value. After 7 yr of age, serum trypsinogen can reliably distinguish between CF patients with and without pancreatic insufficiency.

Age-related alterations in immunoreactive pancreatic lipase and cationic trypsinogen in young children with cystic fibrosis

Serum immunoreactive pancreatic lipase and cationic trypsinogen are elevated in young infants with cystic fibrosis (CF) and may be useful neonatal screening tests for CF. We compared lipase measured by a recently developed ELISA immunoassay with trypsinogen measured by radioimmunoassay in 70 children (ages 0.1 to 9.9 years) with CF who had various degrees of pancreatic dysfunction and in 79 similarly aged children without CF (controls). In the control children, lipase activity increased with advancing age, whereas trypsinogen showed no age-related trend. Lipase and trypsinogen were significantly elevated in the infants with CF who were younger than 1 year, irrespective of pancreatic function (trypsinogen, P<0.001; lipase, P<0.05). Sensitivities in detecting CF were 76% and 90% for lipase and trypsinogen, respectively. After the first year of life, lipase and trypsinogen values declined toward normal, the rate of decline of lipase being greater than that of trypsinogen; 67% of lipase values were within or below the normal range by 3 years, whereas 67% of trypsinogen values continued to be elevated. We conclude that trypsinogen is an excellent screening test for CF in young infants regardless of pancreatic function, and that the addition of a serum pancreatic lipase determination does not improve the accuracy of trypsinogen as a screening test for cystic fibrosis.

The Connor-Davidson Resilience Scale (CD-RISC): Dimensionality and age-related measurement invariance with Australian cricketers

Objective This study explored the dimensionality and measurement invariance of the 25-item Connor-Davidson Resilience Scale (CD-RISC; Connor & Davidson, 2003) across samples of adult (n = 321; aged 20–36) and adolescent (n = 199; aged 12–18) Australian cricketers. Design Cross-sectional, self-report survey Methods An online, multi-section questionnaire. Results Confirmatory factor and item level analyses supported the psychometric superiority of a revised 10-item, unidimensional model of resilience over the original 25-item, five-factor measurement model. Positive and moderate correlations with hardiness as well as negative and moderate correlations with burnout components were evidenced thereby providing support for the convergent validity of the unidimensional model. Measurement invariance analyses of the unidimensional model across the two age-group samples supported configural (i.e., same factor structure across groups), metric (i.e., same pattern of factor loadings across the groups), and partial scalar invariance (i.e., mostly the same intercepts across the groups). Conclusion Evidence for a psychometrically sound measure of resilient qualities of the individual provides an important foundation upon which researchers can identify the antecedents to and outcomes of resilience in sport contexts.

Age-related changes in hepatic function: An update on implications for drug therapy

The accumulation of deficits with increasing age results in a decline in the functional capacity of multiple organs and systems. These changes can have a significant influence on the pharmacokinetics and pharmacodynamics of prescribed drugs. Although alterations in body composition and worsening renal clearance are important considerations, for most drugs the liver has the greatest effect on metabolism. Age-related change in hepatic function thereby causes much of the variability in older people’s responses to medication. In this review, we propose that a decline in the ability of the liver to inactivate toxins may contribute to a proinflammatory state in which frailty can develop. Since inflammation also downregulates drug metabolism, medication prescribed to frail older people in accordance with disease-specific guidelines may undergo reduced systemic clearance, leading to adverse drug reactions, further functional decline and increasing polypharmacy, exacerbating rather than ameliorating frailty status. We also describe how increasing chronological age and frailty status impact liver size, blood flow and protein binding and enzymes of drug metabolism. This is used to contextualise our discussion of appropriate prescribing practices. For example, while the general axiom of ‘start low, go slow’ should underpin the initiation of medication (titrating to a defined therapeutic goal), it is important to consider whether drug clearance is flow or capacity-limited. By summarising the effect of age-related changes in hepatic function on medications commonly used in older people, we aim to provide a guide that will have high clinical utility for practising geriatricians.

Professor age and research assistant ratings of passive-avoidant and proactive leadership: The role of age-related work concerns and age stereotypes

Recent research has shown that, in general, older professors are rated to have more passive-avoidant leadership styles than younger professors by their research assistants. The current study investigated professors' age-related work concerns and research assistants' favorable age stereotypes as possible explanations for this finding. Data came from 128 university professors paired to one research assistant each. Results show that professors' age-related work concerns (decreased enthusiasm for research, growing humanism, development of exiting consciousness and increased follower empowerment) did not explain the relationships between professor age and research assistant ratings of passive-avoidant and proactive leadership. However, research assistants' favorable age stereotypes influenced the relationships between professor age and research assistant ratings of leadership, such that older professors were rated as more passive-avoidant and less proactive than younger professors by research assistants with less favorable age stereotypes, but not by research assistants with more favorable age stereotypes.

Was wollen jüngere und ältere Erwerbstätige erreichen? Altersbezogene Unterschiede in den Inhalten und Merkmalen beruflicher Ziele [What do younger and older workers want to accomplish? Age-related differences in content and characteristics of occupational goals ]

Demographic changes necessitate that companies commit younger workers and motivate older workers through work design. Age-related differences in occupational goals should be taken into account when accomplishing these challenges. In this study, we investigated goal contents and goal characteristics of employees from different age groups. We surveyed 150 employees working in the service sector (average age = 44 years, age range 19 to 60 years) on their most important occupational goals. Employees who stated goals from the area of organizational citizenship were significantly older than employees with other goals. Employees who stated goals from the areas of training and pay/career were significantly younger than employees with other goals. After controlling for gender, education, and work characteristics, no age-related differences were found in the goal areas teamwork, job security, working time, well-being, and new challenges. In addition, no relationships were found between age and the goal characteristics specificity, planning intensity, as well as positive and negative goal emotions. We recommend that companies provide older workers with more opportunities for organizational citizenship and commit younger workers by providing development opportunities and adequate pay