Sex- and Age-Related Temporal Variations in Intestinal-Epithelium Proliferation in the Suckling Mouse

Intestinal-crypt enterocytes are a cell population undergoing constant renewal in the mouse. Both adult and 28 d old animals have been shown to exhibit circadian rhythms in cell proliferative indices, but there are only scant data on the 24 h mitotic activity in the small and large intestine of younger mice. The present studies were thus undertaken in order to characterize the proliferative pattern of enterocytes in the duodenum and colon of 7 and 14 d old males and females of the C3H/S strain. Animals of each sex and from each age group were sacrificed every 4 h during a 24 h span, with each animal receiving an injection of colchicine 4 h before sacrifice. Samples of duodenum and colon were removed and processed for hematoxylin–eosin staining. Twenty longitudinally sectioned crypts within each sample were analyzed, and the mitotic indices of both cell populations from each animal were estimated. The arithmetic mean±SEM for each experimental group were then calculated and the statistical significance of differences between the means assessed by ANOVA and Student t-tests. We observed a greater daily mitotic activity in the duodenum than the colon, and moreover enterocytic proliferation in both those regions was greater in 14 than 7 d old animals. Twenty-four hour variations in mitotic activity occurred in all the experimental groups and tissues except for the large intestine of 7 d old females. Finally, the temporal profile of epithelium proliferation in the suckling mouse varied with age, sex, and site of the intestine studied.     

Fundamental Differences in Visual Perceptual Learning between Children and Adults

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Tuning to the Positive: Age-Related Differences in Subjective Perception of Facial Emotion

Facial expressions aid social transactions and serve as socialization tools, with smiles signaling approval and reward, and angry faces signaling disapproval and punishment. The present study examined whether the subjective experience of positive vs. negative facial expressions differs between children and adults. Specifically, we examined age-related differences in biases toward happy and angry facial expressions. Young children (5–7 years) and young adults (18–29 years) rated the intensity of happy and angry expressions as well as levels of experienced arousal. Results showed that young children—but not young adults—rated happy facial expressions as both more intense and arousing than angry faces. This finding, which we replicated in two independent samples, was not due to differences in the ability to identify facial expressions, and suggests that children are more tuned to information in positive expressions. Together these studies provide evidence that children see unambiguous adult emotional expressions through rose-colored glasses, and suggest that what is emotionally relevant can shift with development.     

Age-Related Differences in Synaptosomal Peroxidative Damage and Membrane Properties

Young, adult, and old rats were used to study the effect of age on the integrity and functioning of brain synaptosomes. An evaluation was made of the differences in lipid composition, membrane fluidity, Na+, K(+)-ATPase activity, and susceptibility to in vitro lipid peroxidation. There was an age-related increase in synaptosomal free fatty acids, with no modification in acyl chain composition, and a decrease in membrane phospholipids which increased the cholesterol/phospholipid mole ratio. With altered lipid composition, there was a corresponding age-dependent decrease in membrane fluidity, a reduction of Na+, K(+)-ATPase activity, and an overall greater susceptibility to in vitro lipid peroxidation. Furthermore, lipid peroxidation promoted strong modifications of the membrane fluidity, lipid composition, and Na+,K(+)-ATPase activity just as aging did, thus indicating a possible contribution of oxidative damage to ageing processes. The cases studied revealed that the greater responsiveness of old membranes to in vitro lipid peroxidation resulted in the highest degree of membrane alteration, indicating that all pathological states known to promote a peroxidative injury can have even more dramatic consequences when they take place in old brain.     

Age-Related Differences of Blood Pressure Profile in Essential Hypertension

The purpose was to assess age-related circadian changes of blood pressure profile (BPP) employing a truncated Fourier series with four harmonics (tFs) in patients with essential hypertension. The study was performed on 32 patients with essential hypertension divided in two groups: (A) 15 patients younger than 55 years and (B) 17 patients older than 60 years. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were monitored every 20 minutes for 24h with a noninvasive portable device (SpaceLabs 90202). To evaluate the existence of SBP and DBP circadian rhythms a one-sample runs-test was performed and the mesor, amplitude, and acrophase from the overall curve of each patient were obtained by tFs. In both groups, SBP and DBP profiles showed a first peak in the late morning and a second peak in the early evening around the same hours. The two peaks in the SBP profile were higher and the two peaks in the DBP profile were lower in older patients than in younger ones (p. 01, p <. 05, p>. 3, p>. 05). The truncated Fourier series with four harmonics evidences different age-related BP profiles characterized by two peaks with higher SBP and lower DBP in elderly patients. These changes of BPP are in accordance with the reported higher risk of cardiovascular events observed around the same hours. (Chronobiology International, 14(4), 397–407, 1997)     

Differences in the Triglyceride to HDL-Cholesterol Ratio between Palestinian and Israeli Adults

Aims

To evaluate differences in the triglyceride to HDL-cholesterol ratio (TG/HDL), thought to be a proxy measure of insulin resistance, between Palestinian and Israeli adults in view of the greater incidence of coronary heart disease and high prevalence of diabetes in Palestinian Arabs.

Research Methods

A population-based observational prevalence study of cardiovascular and diabetes risk factors in Jerusalem. Participants (968 Palestinians, 707 Israelis, sampled at ages 25-74 years) underwent fasting and 2h post-75g oral challenge plasma glucose determinations. Metabolic risk was assessed using the surrogate index TG/HDL. Sex-specific comparisons were stratified by categories of body mass index and sex-specific waist circumference quartiles, adjusted by regression for age, glucose tolerance status and use of statins.

Results

Prevalence of overweight and obesity was substantially larger in Palestinians (p = 0.005). Prevalence of diabetes was 2.4 and 4 fold higher among Palestinian men and women, respectively (p<0.001). Adjusted TG/HDL was higher in Palestinians than Israelis across BMI and waist circumference categories (p<0.001 for both). Higher TG/HDL in Palestinians persisted in analyses restricted to participants with normal glucose tolerance and off statins. Notably, higher TG/HDL among Palestinians prevailed at a young age (25-44 years) and in normal weight individuals of both sexes.

Conclusions

Palestinians have a higher TG/HDL ratio than Israelis. Notably, this is evident also in young, healthy and normal weight participants. These findings indicate the need to study the determinants of this biomarker and other measures of insulin resistance in urban Arab populations and to focus research attention on earlier ages: childhood and prenatal stages of development.     

Age-Related Differences in Collagen-Induced Arthritis: Clinical and Imaging Correlations

Arthritis is among the most common chronic diseases in both children and adults. Although intraarticular inflammation is the feature common among all patients with chronic arthritis there are, in addition to age at onset, clinical characteristics that further distinguish the disease in pediatric and adult populations. In this study, we aimed to demonstrate the utility of microCT (µCT) and ultrasonography in characterizing pathologic age-related differences in a collagen-induced arthritis (CIA) rat model. Juvenile (35 d old) and young adult (91 d old) male Wistar rats were immunized with bovine type II collagen and incomplete Freund adjuvant to induce polyarthritis. Naïve male Wistar rats served as controls. All paws were scored on a scale of 0 (normal paw) to 4 (disuse of paw). Rats were euthanized at 14 d after the onset of arthritis and the hindpaws imaged by µCT and ultrasonography. Young adult rats had more severe signs of arthritis than did their juvenile counterparts. Imaging demonstrated that young adult CIA rats exhibited more widespread and severe skeletal lesions of the phalanges, metatarsals, and tarsal bones, whereas juvenile CIA rats had more localized and less proliferative and osteolytic damage that was confined predominantly to the phalanges and metatarsals. This report demonstrates the utility of imaging modalities to compare juvenile and young adult rats with CIA and provides evidence that disease characteristics and progression differ between the 2 age groups. Our observations indicate that the CIA model could help discern age-related pathologic processes in inflammatory joint diseases.Abbreviations: μCT, microCT, CIA, collagen-induced arthritisArthritis is among the most common diseases in both children and adults. In children, growth, hormonal changes, and neuroimmune responsiveness and plasticity might confer influences on arthritic processes not seen in adults. Age-dependent outcomes have been demonstrated by using animal models of osteoarthritis;^5,6,11 however, there is limited information about how pathogenic processes vary among different age groups with experimental inflammatory arthritis in general^7,10 and in the collagen-induced arthritis (CIA) model of arthritis in particular.⁸ Studying and comparing features of the CIA model in growing compared with mature rats can be undertaken in ways that are not possible in humans and could help to understand age-related pathologic differences in children and adults with inflammatory joint diseases. Therefore, we undertook to compare clinical and imaging features of CIA in juvenile (growing) compared with young adult (mature) rats.In some animal models, collagen immunization results in a monophasic, polyarticular, inflammatory arthritis that is mediated by an autoimmune response¹⁴ and that is histopathologically similar to rheumatoid arthritis.^3,9,13 CIA predominantly affects the peripheral appendicular joints and is characterized by intense synovitis and pannus formation, with consequent erosions of cartilage and subchondral bone.^12,15Here we report that juvenile and young adult rats differ in their clinical responses to collagen immunization and that, according to findings from microCT (µCT) and ultrasonography, juvenile and young adult rats differ in their responses to collagen immunization with regard to disease pathology.     

Differential Sensitivity of Children and Adults to Chemical Toxicity

Children, particularly neonates, can be biologically more sensitive to the same toxicant on a body weight basis than adults. Current understanding of the rates of maturation of metabolism and evidence from case studies indicate that human infants up to 6 months of age typically lack the capacity to detoxify and eliminate substances as readily as adults. For most chemicals, the infant physiologic systems usually produce higher blood levels for longer periods. The newborn's metabolic capacity rapidly matures and, by 6 months of age, children are usually not more sensitive than adults based on their pharmacokinetic competence. Whether children are at greater risk from chemical exposures is another question. Drawing conclusions about the ability of the U.S. Environmental Protection Agency's intraspecies (UF_H) and database (UF_D) uncertainty factors to protect children on the basis of the modest data available is challenging. However, virtually all studies available suggest that a high percentage of the population, including children, is protected by using a 10-fold UF_H or by using a 3.16-fold factor each for toxicokinetic and toxicodynamic variability. Based on specific comparisons for newborns, infants, children, adults and those with severe disease, the population protected is between 60% and 100%, with the studies in larger populations that include sensitive individuals suggesting that the value is closer to 100%. UF_D is likewise protective when used with databases that are missing substantive studies.     

Phase- and Age-Related Differences in Protein Tyrosine Phosphorylation in Sequoia sempervirens

Apical and basal halves of 3 cm long apical segments of in vitro cultured juvenile, adult and rejuvenated Sequoia sempervirens shoots were analyzed for total and tyrosine phosphorylated proteins. The latter was detected by a phosphotyrosine specific antibody. Younger tissues, or the apical halves of shoot terminals, showed larger amounts of 36, 44, 46 kDa proteins and lesser amounts of 29 kDa proteins. These are proposed as age-related changes. Phase-related proteins were also evident. Adult tissues contained more of the 34 and 36 kDa proteins than juvenile and rejuvenated shoots. Western blotting with a phosphotyrosine specific antibody revealed more of 25, 39, and 54 kDa protein in the younger tissues. In addition, tyrosine phosphorylated proteins of 25 and 34 kDa were higher in the adult, than in juvenile or rejuvenated tissues. Our findings showed that protein tyrosine phosphorylation, or the signal transduction pathway, is involved in phase- and age-related processes.     

Age-Related Differences in the Accuracy of Web Query-Based Predictions of Influenza-Like Illness

BackgroundWeb queries are now widely used for modeling, nowcasting and forecasting influenza-like illness (ILI). However, given that ILI attack rates vary significantly across ages, in terms of both magnitude and timing, little is known about whether the association between ILI morbidity and ILI-related queries is comparable across different age-groups. The present study aimed to investigate features of the association between ILI morbidity and ILI-related query volume from the perspective of age.MethodsSince Google Flu Trends is unavailable in Italy, Google Trends was used to identify entry terms that correlated highly with official ILI surveillance data. All-age and age-class-specific modeling was performed by means of linear models with generalized least-square estimation. Hold-out validation was used to quantify prediction accuracy. For purposes of comparison, predictions generated by exponential smoothing were computed.ResultsFive search terms showed high correlation coefficients of > .6. In comparison with exponential smoothing, the all-age query-based model correctly predicted the peak time and yielded a higher correlation coefficient with observed ILI morbidity (.978 vs. .929). However, query-based prediction of ILI morbidity was associated with a greater error. Age-class-specific query-based models varied significantly in terms of prediction accuracy. In the 0–4 and 25–44-year age-groups, these did well and outperformed exponential smoothing predictions; in the 15–24 and ≥ 65-year age-classes, however, the query-based models were inaccurate and highly overestimated peak height. In all but one age-class, peak timing predicted by the query-based models coincided with observed timing.ConclusionsThe accuracy of web query-based models in predicting ILI morbidity rates could differ among ages. Greater age-specific detail may be useful in flu query-based studies in order to account for age-specific features of the epidemiology of ILI.     

Age Differences in Intra-Individual Variability in Simple and Choice Reaction Time: Systematic Review and Meta-Analysis

Background

Intra-individual variability in reaction time (RT IIV) is considered to be an index of central nervous system functioning. Such variability is elevated in neurodegenerative diseases or following traumatic brain injury. It has also been suggested to increase with age in healthy ageing.

Objectives

To investigate and quantify age differences in RT IIV in healthy ageing; to examine the effect of different tasks and procedures; to compare raw and mean-adjusted measures of RT IIV.

Data Sources

Four electronic databases: PsycINFO, Medline, Web of Science and EMBASE, and hand searching of reference lists of relevant studies.

Study Eligibility

English language journal articles, books or book chapters, containing quantitative empirical data on simple and/or choice RT IIV. Samples had to include younger (under 60 years) and older (60 years and above) human adults.

Study Appraisal and Synthesis

Studies were evaluated in terms of sample representativeness and data treatment. Relevant data were extracted, using a specially-designed form, from the published report or obtained directly from the study authors. Age-group differences in raw and RT-mean-adjusted measures of simple and choice RT IIV were quantified using random effects meta-analyses.

Results

Older adults (60+ years) had greater RT IIV than younger (20–39) and middle-aged (40–59) adults. Age effects were larger in choice RT tasks than in simple RT tasks. For all measures of RT IIV, effect sizes were larger for the comparisons between older and younger adults than between older and middle-aged adults, indicating that the age-related increases in RT IIV are not limited to old age. Effect sizes were also larger for raw than for RT-mean-adjusted RT IIV measures.

Conclusions

RT IIV is greater among older adults. Some (but not all) of the age-related increases in RT IIV are accounted for by the increased RT means.     

Gender and Age Differences in Hourly and Daily Patterns of Sedentary Time in Older Adults Living in Retirement Communities

Background

Total sedentary time varies across population groups with important health consequences. Patterns of sedentary time accumulation may vary and have differential health risks. The purpose of this study is to describe sedentary patterns of older adults living in retirement communities and illustrate gender and age differences in those patterns.

Methods

Baseline accelerometer data from 307 men and women (mean age = 84±6 years) who wore ActiGraph GT3X+ accelerometers for ≥ 4 days as part of a physical activity intervention were classified into bouts of sedentary time (<100 counts per minute). Linear mixed models were used to account for intra-person and site-level clustering. Daily and hourly summaries were examined in mutually non-exclusive bouts of sedentary time that were 1+, 5+, 10+, 20+, 30+, 40+, 50+, 60+, 90+ and 120+ minutes in duration. Variations by time of day, age and gender were explored.

Results

Men accumulated more sedentary time than women in 1+, 5+, 10+, 20+, 30+, 40+, 50+ and 60+ minute bouts; the largest gender-differences were observed in 10+ and 20+ minute bouts. Age was positively associated with sedentary time, but only in bouts of 10+, 20+, 30+, and 40+ minutes. Women had more daily 1+ minute sedentary bouts than men (71.8 vs. 65.2), indicating they break up sedentary time more often. For men and women, a greater proportion of time was spent being sedentary during later hours of the day than earlier. Gender differences in intra-day sedentary time were observed during morning hours with women accumulating less sedentary time overall and having more 1+ minute bouts.

Conclusions

Patterns identified using bouts of sedentary time revealed gender and age differences in the way in which sedentary time was accumulated by older adults in retirement communities. Awareness of these patterns can help interventionists better target sedentary time and may aid in the identification of health risks associated with sedentary behavior. Future studies should investigate the impact of patterns of sedentary time on healthy aging, disease, and mortality.     

Age-Related Features of Morphological and Functional Development of Myocardium in Children of Five to Nine Years

Age-related features of the morphological and functional development of the myocardium were studied by echo- (EchoCG) and electrocardiography (ECG) in 200 children five to nine years of age. The most intensive anatomical development of myocardium was observed at the age of five to seven years, and a significant increase in cardiac output was observed at the age of eight to nine years both in boys and girls. The ECG amplitude and time parameters significantly changed from of five to nine years of age and were most pronounced at the age of seven to eight years. Different changes in cardiac rhythm and excitation conduction as well as repolarization and metabolic disturbances in the myocardium were often observed at this age. Static physical exercise caused marked changes in bioelectric activity of the myocardium. Two types of central circulatory responses to static exercise were found: an increase and a decrease in cardiac output. The mechanisms of cardiac rhythm regulation, which caused an increase in the stroke volume as a response to exercise, were different in children from five to nine years old. At the age of five to six years the homeometric mechanism was a crucial factor in the increase in stroke volume as a response to exercise, and at the age of seven to nine years both homeo- and heterometric mechanisms of cardiac rhythm regulation were very important.     

Gender and Age-Related Differences in Bilateral Lower Extremity Mechanics during Treadmill Running

Female runners have a two-fold risk of sustaining certain running-related injuries as compared to their male counterparts. Thus, a comprehensive understanding of the sex-related differences in running kinematics is necessary. However, previous studies have either used discrete time point variables and inferential statistics and/or relatively small subject numbers. Therefore, the first purpose of this study was to use a principal component analysis (PCA) method along with a support vector machine (SVM) classifier to examine the differences in running gait kinematics between female and male runners across a large sample of the running population as well as between two age-specific sub-groups. Bilateral 3-dimensional lower extremity gait kinematic data were collected during treadmill running. Data were analysed on the complete sample (n = 483: female 263, male 220), a younger subject group (n = 56), and an older subject group (n = 51). The PC scores were first sorted by the percentage of variance explained and we also employed a novel approach wherein PCs were sorted based on between-gender statistical effect sizes. An SVM was used to determine if the sex and age conditions were separable and classifiable based on the PCA. Forty PCs explained 84.74% of the variance in the data and an SVM classification accuracy of 86.34% was found between female and male runners. Classification accuracies between genders for younger subjects were higher than a subgroup of older runners. The observed interactions between age and gender suggest these factors must be considered together when trying to create homogenous sub-groups for research purposes.     

Age-Related Differences in NMDA Receptor Subunits of Prenatally Methamphetamine-Exposed Male Rats

There is accumulating evidence that methamphetamine (MA) is a widely abused drug popular among pregnant women. MA exposure is associated with changes in the function of neurotransmitter systems, namely the dopaminergic, serotonergic and glutamatergic systems. Since N-methyl-d-aspartate receptors (NMDA) are affected by MA-induced glutamate release, we assessed the expression of NMDAR subunits (NR1, NR2A, and NR2B) and postsynaptic density protein 95 (PSD-95), which is connected with NMDAR. We measured the expression of these proteins in adolescent (30 days old) and adult (60 days old) rat males exposed to MA during the entire prenatal period and compared them with the same parameters in age matched saline-exposed rats. There was a significant increase in the NR1 and NR2B subunits in the hippocampus of adult males, but not in adolescent males. We identified a significant change in adult MA-induced rats when compared to adult controls for NR2A and NR2B, while in adolescent MA rats this change was close to the boundary of significance. In summary, our study suggests that prenatal MA exposure is connected with changes in NMDAR subunit expression in adult rats but not in adolescent rats.     

Gender Differences in the Social Pathways Linking Neighborhood Disadvantage to Depressive Symptoms in Adults

Depression debilitates the lives of millions and is projected to be the second leading disease burden worldwide by 2020. At the population level, the causes of depression are found in the everyday social and physical environments in which people live. Research has shown that men and women often experience neighbourhood environments differently and that these variations are often reflected in health outcomes. The current study examines whether social and environmental correlates of depression are similar in men and women. This study examines whether (i) there are gender differences in the association between neighbourhood disadvantage and depressive symptoms, and (ii) dimensions of social capital and cohesion mediate these associations. Data come from the Montreal Neighbourhood Networks and Healthy Aging Study, which consists of a cluster stratified sample of Montreal census tracts (n_ct = 300) and individuals within those tracts (n_i = 2707). Depressive symptoms and social capital were measured with a questionnaire. Neighbourhood disadvantage was measured at the census tract level using data from the 2006 Canada Census. Multilevel logistic regression stratified by gender and a three-step mediation analysis procedure were used. Final sample size for these analyses was 2574 adults. Depressive symptoms had a prevalence of 17.3% in the overall sample. Disadvantage was associated with depressive symptoms in women only (OR = 1.25, 95% CI = 1.01–1.55). Perceived neighbourhood cohesion was shown to mediate the association of disadvantage and depressive symptoms in women (ab = 0.02; 95% CI = 0.003–0.04, p<0.05). Other socio-relational variables, specifically generalized trust and trust in neighbours were associated with depression in women but did not act as mediating variables. Health promotion initiatives meant to combat depression may wish to consider gender differences in the design and implementation of neighbourhood or peer-based programs.     

Neural Correlates of Letter Reversal in Children and Adults

Children often make letter reversal errors when first learning to read and write, even for letters whose reversed forms do not appear in normal print. However, the brain basis of such letter reversal in children learning to read is unknown. The present study compared the neuroanatomical correlates (via functional magnetic resonance imaging) and the electrophysiological correlates (via event-related potentials or ERPs) of this phenomenon in children, ages 5–12, relative to young adults. When viewing reversed letters relative to typically oriented letters, adults exhibited widespread occipital, parietal, and temporal lobe activations, including activation in the functionally localized visual word form area (VWFA) in left occipito-temporal cortex. Adults exhibited significantly greater activation than children in all of these regions; children only exhibited such activation in a limited frontal region. Similarly, on the P1 and N170 ERP components, adults exhibited significantly greater differences between typical and reversed letters than children, who failed to exhibit significant differences between typical and reversed letters. These findings indicate that adults distinguish typical and reversed letters in the early stages of specialized brain processing of print, but that children do not recognize this distinction during the early stages of processing. Specialized brain processes responsible for early stages of letter perception that distinguish between typical and reversed letters may develop slowly and remain immature even in older children who no longer produce letter reversals in their writing.     

Cardiac Pacing and Defibrillation in Children and Young Adults

The population of children and young adults requiring a cardiac pacing device has been consistently increasing. The current generation of devices are small with a longer battery life, programming capabilities that can cater to the demands of the young patients and ability to treat brady and tachyarrhythmias as well as heart failure. This has increased the scope and clinical indications of using these devices. As patients with congenital heart disease (CHD) comprise majority of these patients requiring devices, the knowledge of indications, pacing leads and devices, anatomical variations and the technical skills required are different than that required in the adult population. In this review we attempt to discuss these specific points in detail to improve the understanding of cardiac pacing in children and young adults.