scholarly journals Age-related differences in heat loss capacity occur under both dry and humid heat stress conditions

2014 ◽  
Vol 117 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Joanie Larose ◽  
Pierre Boulay ◽  
Heather E. Wright-Beatty ◽  
Ronald J. Sigal ◽  
Stephen Hardcastle ◽  
...  
Keyword(s):  
Heat Stress ◽  
Relative Humidity ◽  
Heat Loss ◽  
Heat Dissipation ◽  
Heat Storage ◽  
Intermittent Exercise ◽  
Age Groups ◽  
Evaporative Heat Loss ◽  
Age Group ◽  
Age Related

This study examined the progression of impairments in heat dissipation as a function of age and environmental conditions. Sixty men ( n = 12 per group; 20–30, 40–44, 45–49, 50–54, and 55–70 yr) performed four intermittent exercise/recovery cycles for a duration of 2 h in dry (35°C, 20% relative humidity) and humid (35°C, 60% relative humidity) conditions. Evaporative heat loss and metabolic heat production were measured by direct and indirect calorimetry, respectively. Body heat storage was measured as the temporal summation of heat production and heat loss during the sessions. Evaporative heat loss was reduced during exercise in the humid vs. dry condition in age groups 20–30 (−17%), 40–44 (−18%), 45–49 (−21%), 50–54 (−25%), and 55–70 yr (−20%). HE fell short of being significantly different between groups in the dry condition, but was greater in age group 20–30 yr (279 ± 10 W) compared with age groups 45–49 (248 ± 8 W), 50–54 (242 ± 6 W), and 55–70 yr (240 ± 7 W) in the humid condition. As a result of a reduced rate of heat dissipation predominantly during exercise, age groups 40–70 yr stored between 60–85 and 13–38% more heat than age group 20–30 yr in the dry and humid conditions, respectively. These age-related differences in heat dissipation and heat storage were not paralleled by significant differences in local sweating and skin blood flow, or by differences in core temperature between groups. From a whole body perspective, combined heat and humidity impeded heat dissipation to a similar extent across age groups, but, more importantly, intermittent exercise in dry and humid heat stress conditions created a greater thermoregulatory challenge for middle-aged and older adults.

scholarly journals Whole body heat loss is reduced in older males during short bouts of intermittent exercise

2013 ◽  
Vol 305 (6) ◽  
pp. R619-R629 ◽  
Author(s):  
Joanie Larose ◽  
Heather E. Wright ◽  
Jill Stapleton ◽  
Ronald J. Sigal ◽  
Pierre Boulay ◽  
...  
Keyword(s):  
Heat Loss ◽  
Heat Storage ◽  
Intermittent Exercise ◽  
Heat Content ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Middle Aged ◽  
Young Males ◽  
Body Heat ◽  
Older Males

Studies in young adults show that a greater proportion of heat is gained shortly following the start of exercise and that temporal changes in whole body heat loss during intermittent exercise have a pronounced effect on body heat storage. The consequences of short-duration intermittent exercise on heat storage with aging are unclear. We compared evaporative heat loss (H E) and changes in body heat content (ΔHb) between young (20–30 yr), middle-aged (40–45 yr), and older males (60–70 yr) of similar body mass and surface area, during successive exercise (4 × 15 min) and recovery periods (4 × 15 min) at a fixed rate of heat production (400 W) and under fixed environmental conditions (35°C/20% relative humidity). H E was lower in older males vs. young males during each exercise (Ex1: 283 ± 10 vs. 332 ± 11 kJ, Ex2: 334 ± 10 vs. 379 ± 5 kJ, Ex3: 347 ± 11 vs. 392 ± 5 kJ, and Ex4: 347 ± 10 vs. 387 ± 5 kJ, all P < 0.02), whereas H E in middle-aged males was intermediate to that measured in young and older adults (Ex1: 314 ± 13, Ex2: 355 ± 13, Ex3: 371 ± 13, and Ex4: 365 ± 8 kJ). H E was not significantly different between groups during the recovery periods. The net effect over 2 h was a greater ΔHb in older (267 ± 33 kJ; P = 0.016) and middle-aged adults (245 ± 16 kJ; P = 0.073) relative to younger counterparts (164 ± 20 kJ). As a result of a reduced capacity to dissipate heat during exercise, which was not compensated by a sufficiently greater rate of heat loss during recovery, both older and middle-aged males had a progressively greater rate of heat storage compared with young males over 2 h of intermittent exercise.

scholarly journals Influence of Patient Age on Streptococcus pneumoniae Serotypes Causing Invasive Disease

2001 ◽  
Vol 8 (3) ◽  
pp. 556-559 ◽  
Author(s):  
Jaime Inostroza ◽  
Ana Maria Vinet ◽  
Gloria Retamal ◽  
Pedro Lorca ◽  
Gonzalo Ossa ◽  
...  
Keyword(s):  
Age Groups ◽  
Invasive Disease ◽  
Bacterial Virulence ◽  
Host Factors ◽  
Invasive Infection ◽  
Age Group ◽  
Southern Chile ◽  
Age Related ◽  
Sterile Site ◽  
Selection Of

ABSTRACT All clinical S. pneumoniae specimens isolated from patients with invasive or sterile-site infections admitted to one regional general hospital in southern Chile were collected during a 5-year period (February 1994 to September 1999). A total of 247 strains belonging to 50 serotypes were isolated in this survey: 69 in patients under 5 years of age, 129 in patients 5 to 64 years old, and 49 from patients 65 years and older. Eight serotypes were identified in all age groups, while all other serotypes were found exclusively in one age group or in patients over 4 years of age. Serotype 3 was never found in patients under 5 years old, and serotype 14 was not found in patients >64 years of age. There was no difference in the serotypes causing infection in each one of the 5 years of the survey. Our results suggest that both bacterial virulence factors and host factors play an important role in the selection of S. pneumoniae serotypes causing invasive infection. Possible host factors include age-related differences in the immune response. Comparative studies with other areas of the world may help to further understanding of our observations in southern Chile.

Age and outcome after aneurysmal subarachnoid hemorrhage: why do older patients fare worse?

1996 ◽  
Vol 85 (3) ◽  
pp. 410-418 ◽  
Author(s):  
Giuseppe Lanzino ◽  
Neal F. Kassell ◽  
Teresa P. Germanson ◽  
Gail L. Kongable ◽  
Laura L. Truskowski ◽  
...  
Keyword(s):  
Prognostic Factors ◽  
Subarachnoid Hemorrhage ◽  
Age Groups ◽  
Age Group ◽  
Content Type ◽  
Poor Outcome ◽  
Symptomatic Vasospasm ◽  
Age Related ◽  
Increased Risk ◽  
Fine Print

✓ Advanced age is a recognized prognostic indicator of poor outcome after subarachnoid hemorrhage (SAH). The relationship of age to other prognostic factors and outcome was evaluated using data from the multicenter randomized trial of nicardipine in SAH conducted in 21 neurosurgical centers in North America. Among the 906 patients who were studied, five different age groups were considered: 40 years or less, 41 to 50, 51 to 60, 61 to 70, and more than 71 years. Twenty-three percent of the individuals enrolled were older than 60 years of age. Women outnumbered men in all age groups. Level of consciousness (p = 0.0002) and World Federation of Neurological Surgeons grade (p = 0.0001) at admission worsened with advancing age. Age was also related to the presence of a thick subarachnoid clot (p = 0.0001), intraventricular hemorrhage (p = 0.0003), and hydrocephalus (p = 0.0001) on an admission computerized tomography scan. The rebleeding rate increased from 4.5% in the youngest age group to 16.4% in patients more than 70 years of age (p = 0.002). As expected, preexisting medical conditions, such as diabetes (p = 0.028), hypertension (p = 0.0001), and pulmonary (p = 0.0084), myocardial (p = 0.0001), and cerebrovascular diseases (p = 0.0001), were positively associated with age. There were no age-related differences in the day of admission following SAH, timing of the surgery and/or location, and size (small vs. large) of the ruptured aneurysm. During the treatment period, the incidence of severe complications (that is, those complications considered life threatening by the reporting investigator) increased with advancing age, occurring in 28%, 33%, 36%, 40%, and 46% of the patients in each advancing age group, respectively (p = 0.0002). No differences were observed in the reported frequency of surgical complications. No age-related differences were found in the overall incidence of angiographic vasospasm; however, symptomatic vasospasm was more frequently reported in the older age groups (p = 0.01). Overall outcome, assessed using the Glasgow Outcome Scale at 3 months post-SAH, was poorer with advancing age (p < 0.001). Multivariate analysis of overall outcome, adjusting for the different prognostic factors, did not remove the age effect, which suggests that the aging brain has a less optimal response to the initial bleeding. Age as a risk factor is a continuum; however, there seems to be a significant increased risk of poor outcome after the age of 60 years.

scholarly journals TSH enhancement of FT4 to FT3 conversion is age dependent

2016 ◽  
Vol 175 (1) ◽  
pp. 49-54 ◽  
Author(s):  
David Strich ◽  
Gilad Karavani ◽  
Shalom Edri ◽  
David Gillis
Keyword(s):  
Age Groups ◽  
Thyroid Stimulating Hormone ◽  
Older Age ◽  
Age Group ◽  
Free T4 ◽  
Free T3 ◽  
Age Related ◽  
Differential Increase ◽  
Retrospective Examination ◽  
Tsh Levels

ObjectiveWe previously reported increasing free T3 (FT3) to free T4 (FT4) ratios as thyroid-stimulating hormone (TSH) increases within the normal range in children. It is not known if this phenomenon is age-related among humans, as previously reported in rats. This study examines the relationships between TSH and FT3/FT4 ratios in different ages.DesignRetrospective examination of thyroid tests from patients without thyroid disease from community clinics.MethodsFree T3, free T4, and TSH levels from 527 564 sera collected from patients aged 1 year or greater were studied. Exclusion criteria were the following: missing data, TSH greater than 7.5mIU/L, and medications that may interfere with thyroid hormone activity. A total of 27 940 samples remaining after exclusion were stratified by age. Samples with available anthropometric data were additionally stratified for body mass index (BMI). Correlations of TSH to FT4, FT3, and FT3/FT4 ratios by age group were examined.ResultsUp to age 40, for each increasing TSH quartile, FT3 and the FT3/FT4 ratio increased and FT4 decreased significantly (for both FT3, FT4 and FT3/FT4 ratio,P<0.05 for every TSH quartile when compared with the 1st quartile, except FT3 in the 30–40 age group). In older age groups, increasing TSH was not associated with increased FT3/FT4 ratio.ConclusionAs TSH levels increase, FT3/FT4 ratios increase until age 40, but this differential increase does not occur in older age groups. This may reflect a decrease in thyroxine (T4) to triiodothyronine (T3) conversion with age, which may be part of the aging process.

scholarly journals Young Children's Exposure to and Ability to Eat Different Food Textures, as Reported by Parents (P11-119-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Sarah Smith-Simpson ◽  
Lisa Fries ◽  
Carolyn Ross
Keyword(s):  
Online Survey ◽  
Age Groups ◽  
Age Group ◽  
Older Children ◽  
Research Issues ◽  
Funding Sources ◽  
Food Texture ◽  
Age Related ◽  
Group Data ◽  
Age Appropriate

Abstract Objectives The objective was to identify the age at which parents expose their children to different food textures and how challenging the textures were for their child to eat. It was hypothesized that older children would be exposed to a wider variety of food textures and that parents would consider a larger proportion of these textures to be easy to eat. Methods Parents (n = 365) in Grand Rapids, MI, USA with a child aged 6–36 months completed an online survey. The survey had 37 questions, including 15 unique food texture categories with food examples (Table 1). Parents were asked how difficult each texture category was for their child to eat using a 5-point scale ranging from “Very Easy” to “Very Difficult”, plus an option for “My child hasn't tried this yet”. Children were divided into 5 age groups (6-8 months, 9–12 months, 13–18 months, 19–24 months, 25–36 months) for analysis. Across texture category and age group, data were analyzed using analysis of variance, with mean separation accomplished using Fisher's LSD (P < 0.05). Results A majority of children in the youngest age group (6-8 months) had only eaten foods described as creamy, dissolvable, or pureed. All of the texture categories had been served to a majority of 9–12 month-old children, except for “hard” and “tough meat”. By 18 months of age, a majority of children had tried all food texture categories except “hard”. Across all age groups, creamy, dissolvable, and puree were rated as easy and “tough meat” was rated as difficult. The other textures showed age-related differences, with parents of older children reporting the textures as easier to eat than those of younger children. Food textures were compared within the 9–12 and 13–18 month age groups, when most new food textures are introduced, and similar trends were observed. The easiest textures were creamy, dissolvable, puree and soft, followed by lumpy and juicy, then slippery, chewy, rubbery, and sticky. The most difficult textures were leafy, with skin, hard, tough meat and combination of textures. Conclusions When considering textures of the foods that comprise a well-balanced, healthy diet, many foods are difficult for children to eat. Preparing foods such as green vegetables specifically to have age-appropriate textures could improve consumption. Funding Sources Washington State Univ College of Agricultural, Human and Natural Resource Emerging Research Issues Grant.

Effect of heating rate on evaporative heat loss in the microwave-exposed mouse

1982 ◽  
Vol 53 (2) ◽  
pp. 316-323 ◽  
Author(s):  
C. J. Gordon
Keyword(s):  
Body Temperature ◽  
Heat Loss ◽  
Heat Dissipation ◽  
Dew Point ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Heat Absorption ◽  
Deep Body Temperature ◽  
The Difference ◽  
Body Heat

Male CBA/J mice were administered heat loads of 0–28 J X g-1 at specific absorption rates (SARs) of either 47 or 93 W X kg-1 by exposure to 2,450-MHz microwave radiation at an ambient temperature of 30 degrees C while evaporative heat loss (EHL) was continuously monitored with dew-point hygrometry. At an SAR of 47 W X kg-1 a threshold heat load of 10.5 J X g-1 had to be exceeded before EHL increased. An approximate doubling of SAR to 93 W X kg-1 reduced the threshold to 5.2 J X g-1. Above threshold the slopes of the regression lines were 1.15 and 0.929 for the low- and high-SAR groups, respectively. Thus the difference in threshold and not slope attributes to the significant increase in EHL when mice are exposed at a high SAR (P less than 0.02). In separate experiments a SAR of 47 W X kg-1 raised the deep body temperature of anesthetized mice at a rate of 0.026 degrees C X s-1, whereas 93 W X kg-1 raised temperature at 0.049 degrees C X s-1. Hence the sensitivity of the EHL mode of heat dissipation is directly proportional to the rate of heat absorption and to the rate of rise in body temperature. These data contradict the notion that mammals have control over whole-body heat exchange only (i.e., thermoregulation) but instead indicate that the EHL system is highly responsive to the rate of heat absorption (i.e., temperature regulation).

scholarly journals Assessment of Cognitive Aging Using an SSVEP-Based Brain–Computer Interface System

2019 ◽  
Vol 3 (2) ◽  
pp. 29 ◽  
Author(s):  
Saraswati Sridhar ◽  
Vidya Manian
Keyword(s):  
Cognitive Decline ◽  
Cognitive Aging ◽  
Age Groups ◽  
Detection Accuracy ◽  
Cognitive Deterioration ◽  
Age Group ◽  
Frequency Detection ◽  
Band Power ◽  
Age Related ◽  
Bci System

Cognitive deterioration caused by illness or aging often occurs before symptoms arise, and its timely diagnosis is crucial to reducing its medical, personal, and societal impacts. Brain–computer interfaces (BCIs) stimulate and analyze key cerebral rhythms, enabling reliable cognitive assessment that can accelerate diagnosis. The BCI system presented analyzes steady-state visually evoked potentials (SSVEPs) elicited in subjects of varying age to detect cognitive aging, predict its magnitude, and identify its relationship with SSVEP features (band power and frequency detection accuracy), which were hypothesized to indicate cognitive decline due to aging. The BCI system was tested with subjects of varying age to assess its ability to detect aging-induced cognitive deterioration. Rectangular stimuli flickering at theta, alpha, and beta frequencies were presented to subjects, and frontal and occipital Electroencephalographic (EEG) responses were recorded. These were processed to calculate detection accuracy for each subject and calculate SSVEP band power. A neural network was trained using the features to predict cognitive age. The results showed potential cognitive deterioration through age-related variations in SSVEP features. Frequency detection accuracy declined after age group 20–40, and band power declined throughout all age groups. SSVEPs generated at theta and alpha frequencies, especially 7.5 Hz, were the best indicators of cognitive deterioration. Here, frequency detection accuracy consistently declined after age group 20–40 from an average of 96.64% to 69.23%. The presented system can be used as an effective diagnosis tool for age-related cognitive decline.

Sex- and age-related differences in bilirubin concentrations in serum.

1984 ◽  
Vol 30 (8) ◽  
pp. 1380-1382 ◽  
Author(s):  
P Rosenthal ◽  
M Pincus ◽  
D Fink
Keyword(s):  
Serum Bilirubin ◽  
Pearson Correlation ◽  
Age Groups ◽  
Correlation Coefficients ◽  
Bile Pigment ◽  
Age Group ◽  
Age Related ◽  
Liver Functions ◽  
Males And Females ◽  
Age And Sex

Abstract The relation between age and sex and the concentration of bilirubin in serum was evaluated in 6740 men and 11 215 women, ages 13 to 96 years. Mean serum bilirubin concentrations in the men significantly exceeded values in the women over all age groups examined. Further, mean serum bilirubin concentrations were greatest both in males and females in the 19-24 years age group and then declined to former values, which persisted throughout life. Pearson correlation coefficients for bilirubin with liver function indices (albumin and total protein) and with hemoglobin were low in all ages and in both sexes, suggesting that bilirubin concentrations do not correlate with those liver functions not directly concerned with bile pigment processing.

scholarly journals Age-Related Changes in the 25-Hydroxyvitamin D Versus Parathyroid Hormone Relationship Suggest a Different Reason Why Older Adults Require More Vitamin D

2003 ◽  
Vol 88 (1) ◽  
pp. 185-191 ◽  
Author(s):  
Reinhold Vieth ◽  
Yasmin Ladak ◽  
Paul G. Walfish
Keyword(s):  
Older Adults ◽  
Vitamin D ◽  
Secondary Hyperparathyroidism ◽  
Age Groups ◽  
The Elderly ◽  
Age Group ◽  
Hydroxyvitamin D ◽  
Age Related ◽  
25 Hydroxyvitamin D ◽  
The Relationship

Vitamin D requirements are thought to vary with age, but there is little comparative evidence for this. One goal in establishing a vitamin D requirement is to avoid secondary hyperparathyroidism. We studied 1741 euthyroid, thyroid clinic outpatients without evidence of calcium abnormalities, ranging in age from 19 to 97 yr, whose serum and urine had been analyzed for calcium, vitamin D, and parathyroid status. We found no effect of age on the 25-hydroxyvitamin D [25(OH)D] concentration associated with specific vitamin D intakes, and there was no relationship between 25(OH)D and 1,25hydroxyvitamin D [1,25(OH)2D]. In every age group, serum 1,25(OH)2D declined with increasing creatinine (P &lt; 0.001). What changed with age included creatinine, which correlated with 25(OH)D (r = 0.146, P &lt; 0.001) only in the youngest age group (19–50 yr) but not in the older age groups (P &gt; 0.1). Creatinine did not correlate with PTH in the youngest age group, but the relationship became significant as age increased (e.g. for the elderly, r = 0.365, P &lt; 0.001). Linear regression of log PTH vs. log 25(OH)D agreed with the natural shape of the relationship observed with scatterplot smoothing, and this showed no plateau in PTH as 25(OH)D increased. We compared PTH concentrations among age groups, based on 20 nmol/liter increments in 25(OH)D. Mean PTH in adults older than 70 yr was consistently higher than in adults younger than 50 yr (P &lt; 0.05 by ANOVA and Dunnett’s t test). PTH levels of the elderly who had 25(OH)D concentrations greater than 100 nmol/liter matched PTH of younger adults having 25(OH)D concentrations near 70 nmol/liter. This study shows that all age groups exhibit a high prevalence of 25(OH)D insufficiency and secondary hyperparathyroidism. Older adults are just as efficient in maintaining 25(OH)D, but they need more vitamin D to produce the higher 25(OH)D concentrations required to overcome the hyperparathyroidism associated with their diminishing renal function.

SEASONAL AGE DYNAMICS OF EIMERIOSIS AND CRYPTOSPORIDI-OSIS OF CATTLE

2020 ◽  
Vol 3 ◽  
pp. 24-29
Author(s):  
E.S. Klimova ◽  
◽  
M.E. Mkrtchyan ◽  
E.V. Maksimova ◽  
A.D. Reshetnikova ◽  
...  
Keyword(s):  
Seasonal Dynamics ◽  
Preventive Measures ◽  
Age Groups ◽  
Central Zone ◽  
Age Group ◽  
Age Dynamics ◽  
Research Material ◽  
Age Related ◽  
Udmurt Republic

Currently, the topic of determination of the seasonal and age-related dynamics of eimeria and cryptosporidia, especially with their associative course in cattle on farms of the Udmurt Republic, remains relevant. The research material were represented by fecal samples (1629 samples) from animals of various age groups of the central zone of Udmurtia, spontaneously infected with eime-ria and cryptosporidia. Coprological studies were performed monthly by generally accepted flotation methods, and fingerprint smears were made, followed by Ziehl-Nielsen staining. Our studies on the seasonal dynamics of protozoa showed that peaks of infection in animals in the central zone of the Udmurt Republic were noted in the autumn-winter periode. The age dynamics in the regions differed significantly depending on the type of pathogen and the age of the animals. Thus, Zavyalovsky is a stationary dysfunctional area for eimeriosis and cryptosporidiosis, where the per-centage of eimeriosis infection is 96.3%. At the same time, the maximum number of ocists were observed in young animals in age of 8-12 months. Cryptosporidiosis infestation was recorded from 3 days of age to 2 months, and the percentage of infection in this age group reached 89,66%.The results of our studies revealed a fairly widespread association of these protozooses. So, it was found that in Zavyalovsky district, the maximum intensi-ty of mixtinvasion is recorded in animals aged 1-2 months and reaches up to 69,17%. In the Uvinsky district, the greatest degree of infection with the association of eimeria and cryptosporidia is record-ed almost 2 times less often (in 37,31% of cas-es).The results of seasonal dynamics must be taken into account for drawing up treatment and preventive measures for various age groups of animals in the central zone of the Udmurt Republic.

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