Contribution of abdominal adiposity to age-related differences in insulin sensitivity and plasma lipids in healthy nonobese women

WSTĘP. Autorzy sprawdzili słuszność hipotezy zakładającej, że związany z wiekiem przyrost tkanki tłuszczowej trzewnej odpowiada częściowo za ujemny wpływ na insulinowrażliwość i profil lipidowy u kobiet bez otyłości. MATERIAŁ I METODY. Bezpośrednio oceniono: powierzchnię podskórnej i trzewnej tkanki tłuszczowej (tomografia komputerowa), zużycie glukozy (badanie metodą hiperinsulinowej/euglikemicznej klamry metabolicznej), elementy składowe organizmu (metoda absorpcjometrii promieniami X dwoistej energii), profil lipidowy oraz maksymalne zużycie tlenu (VO2max) u 178 kobiet bez otyłości, zakwalifikowanych do odpowiednich grup wiekowych: grupa 1 - 28 &plusmn; 4 lata (n = 88); grupa 2 - 46 &plusmn; 2 lata (n = 38); grupa 3 - 53 &plusmn; 2 lata (n = 31); grupa 4 - 67 &plusmn; 6 lat (n = 21). WYNIKI. Powierzchnia trzewnej tkanki tłuszczowej zwiększa się wraz z wiekiem (2,36 cm2 rocznie, p < 0,0001). Zanotowano związany z wiekiem wzrost stężenia cholesterolu całkowitego (p < 0,0003), triglicerydów (p < 0,0009), cholesterolu frakcji LDL (p < 0,027) i stosunku stężenia cholesterolu całkowitego do cholesterolu frakcji HDL (p < 0,042). Obserwowane różnice w insulinowrażliwości także wiązały się z wiekiem, jednakże w tym przypadku zależność była odmienna. Insulinowrażliwość, wyrażona jako całkowita lub przeliczona na kilogram beztłuszczowej masy ciała, była najniższa w grupie 4, ale nie różniła się istotnie między grupami 1, 2 i 3. Po analizie statystycznej, uwzględniającej powierzchnię tkanki tłuszczowej trzewnej, niższa insulinowrażliwość utrzymywała się, jednocześnie, relatywnie zmniejszyła się różnica w porównaniu z pozostałymi grupami. Wpływ zawartości trzewnej tkanki tłuszczowej na związane z wiekiem zmiany profilu lipidowego był silniejszy. Różnice w powierzchni trzewnej i głębokiej podskórnej tkanki tłuszczowej znosiły wpływ wieku na stężenie cholesterolu całkowitego, triglicerydów i cholesterolu frakcji LDL. Nie obserwowano natomiast wpływu wartości VO2max lub aktywnego wypoczynku na zależne od wieku zmiany w insulinowrażliwości bądź profilu lipidowym. WNIOSKI. 1) Wraz z wiekiem zwiększa się powierzchnia trzewnej tkanki tłuszczowej, podczas gdy zmniejszenie insulinowrażliwości obserwuje się tylko u kobiet starszych; 2) Związane z wiekiem różnice w trzewnej tkance tłuszczowej tylko w niewielkim stopniu odpowiadają za spadek insulinowrażliwości u kobiet bez otyłości; 3) Niepożądane zmiany profilu lipidowego w dużym stopniu wiążą się z zależnym od wieku przyrostem trzewnej tkanki tłuszczowej.INTRODUCTION. We examined the hypothesis that an age-related increase in the compartments of visceral fat would account, in part, for the deleterious changes in insulin sensitivity and blood lipid profile in nonobese women. MATERIAL AND METHODS. We directly assessed visceral and subcutaneous abdominal adipose tissue areas (computed tomography), glucose disposal (hyperinsulinemic-euglycemic clamp), body composition (dual energy X-ray absorptiometry), blood-lipid profile, and aerobic fitness (VO2max) in 178 nonobese women categorized into four age groups: group 1, 28 &plusmn; 4 years, n = 88; group 2, 46 &plusmn; 2 years, n = 38; group 3, 53 &plusmn; 2 years, n = 31; and group 4, 67 &plusmn; 6 years, n = 21. RESULTS. Visceral abdominal adipose tissue area increased with age (2.36 cm2 per year, P < 0.0001). We noted an age-related increase in total cholesterol (P < 0.0003), triglycerides (P < 0.0009), LDL cholesterol (P < 0.027), and the ratio of total cholesterol to HDL cholesterol (P < 0.042). However, agerelated changes in insulin sensitivity exhibited a different age-related pattern. That is, insulin sensitivity, expressed on an absolute basis or indexed per kilogram of fat-free mass, was lowest in group 4 but was not significantly different among groups 1, 2, and 3. After statistical control for visceral fat, lower insulin sensitivity persisted in group 4, although differences were diminished relative to other groups. However, the effect of visceral fat on agerelated changes in the blood-lipid profile was stronger. That is, differences in visceral and deep subcutaneous adipose tissue area abolished age-related differences in total cholesterol, triglycerides, and LDL cholesterol. No independent effects of VO2max or leisure-time physical activity on age-related changes in insulin sensitivity or on the blood-lipid profile were noted. CONCLUSIONS. We conclude that 1) visceral fat shows an increase with advancing age, whereas a decrease in insulin sensitivity was noted only in older women; 2) age-related differences in visceral fat explain only a modest part of the decline in insulin sensitivity in nonobese women; and 3) unfavorable changes in plasma lipids were strongly associated with the age-related increase in visceral abdominal adipose tissue

HERRAMIENTA NUMÉRICA PARA LA EVALUACIÓN DE DESPLAZAMIENTOS DE DOS FASES EN MEDIOS POROSOS USANDO TOMOGRAFÍA COMPUTARIZADA

The annual production of crude oil in Colombia has increased, from year to year, to 367 million barrels per year and a proven reserve of 2002 million barrels in 2016. This is due to the intensified production of mature, and heavy crude, oil fields and the use of Enhanced Oil Recovery Techniques (EOR). These seek to reduce the saturation of crude oil in a reservoir by injecting fluids such as solvents, polymers, steam and air, mainly. The percentage of recovery in Colombia achieved with EOR techniques is close to 21%. However, its effectiveness depends on: the characteristics of the oil present in the reservoir, the thrust mechanism prevailing in this, pressure, and temperature, in addition to the petrophysical properties of the rock that forms the reservoir. This work deals with the estimation of the dynamic petrophysical properties of rock samples from the producer horizon using Computed Tomography (CT). For this, a set of five numerical algorithms is proposed for the estimation of the effective porosity, saturation, forward front, trapped volume, and recovery factor during the displacement of two liquids, crude and water, inside the porous medium. The purpose of the dynamic characterization using CT is to understand and analyze the parameters that influence the success of crude oil displacement in a porous medium as part of an improved production scheme in mature, and heavy crude, oil fields.La producción anual de crudo en Colombia ha aumentado año tras año, hasta alcanzar los 367 millones de barriles por año y una reserva probada de 2002 millones de barriles, en el 2016. Esto se debe a la intensificación de actividades de explotación de yacimientos maduros y de crudo pesado, y el uso de Técnicas de Recobro Mejorado (EOR). Estas buscan reducir la saturación de crudo en un yacimiento mediante la inyección de fluidos como solventes, polímeros, vapor y aire, principalmente. El porcentaje de recuperación en Colombia alcanzado con técnicas EOR es cercano al 21%. No obstante, su efectividad depende de: las características del crudo presente en el yacimiento, el mecanismo de empuje predominante en este, presión y temperatura, además de las propiedades petrofísicas de la roca que forma el yacimiento. Este trabajo aborda la estimación de las propiedades petrofísicas dinámicas de muestras de roca del horizonte productor mediante el uso de Tomografía Computarizada (acorde a sus siglas en inglés CT). Para esto se propone un conjunto de cinco algoritmos numéricos para la estimación de la porosidad efectiva, saturación, frente de avance, volumen atrapado y factor de recobro durante el desplazamiento de dos líquidos, crudo y agua, en el interior del medio poroso. El objetivo de la caracterización dinámica, mediante CT, es comprender y analizar los parámetros que influyen en el éxito de un desplazamiento de crudo en un medio poroso como parte de un esquema de producción mejorado en yacimientos maduros y de crudo pesado

HERRAMIENTA NUMÉRICA PARA LA EVALUACIÓN DE DESPLAZAMIENTOS DE DOS FASES EN MEDIOS POROSOS USANDO TOMOGRAFÍA COMPUTARIZADA

The annual production of crude oil in Colombia has increased, from year to year, to 367 million barrels per year and a proven reserve of 2002 million barrels in 2016. This is due to the intensified production of mature, and heavy crude, oil fields and the use of Enhanced Oil Recovery Techniques (EOR). These seek to reduce the saturation of crude oil in a reservoir by injecting fluids such as solvents, polymers, steam and air, mainly. The percentage of recovery in Colombia achieved with EOR techniques is close to 21%. However, its effectiveness depends on: the characteristics of the oil present in the reservoir, the thrust mechanism prevailing in this, pressure, and temperature, in addition to the petrophysical properties of the rock that forms the reservoir. This work deals with the estimation of the dynamic petrophysical properties of rock samples from the producer horizon using Computed Tomography (CT). For this, a set of five numerical algorithms is proposed for the estimation of the effective porosity, saturation, forward front, trapped volume, and recovery factor during the displacement of two liquids, crude and water, inside the porous medium. The purpose of the dynamic characterization using CT is to understand and analyze the parameters that influence the success of crude oil displacement in a porous medium as part of an improved production scheme in mature, and heavy crude, oil fields.La producción anual de crudo en Colombia ha aumentado año tras año, hasta alcanzar los 367 millones de barriles por año y una reserva probada de 2002 millones de barriles, en el 2016. Esto se debe a la intensificación de actividades de explotación de yacimientos maduros y de crudo pesado, y el uso de Técnicas de Recobro Mejorado (EOR). Estas buscan reducir la saturación de crudo en un yacimiento mediante la inyección de fluidos como solventes, polímeros, vapor y aire, principalmente. El porcentaje de recuperación en Colombia alcanzado con técnicas EOR es cercano al 21%. No obstante, su efectividad depende de: las características del crudo presente en el yacimiento, el mecanismo de empuje predominante en este, presión y temperatura, además de las propiedades petrofísicas de la roca que forma el yacimiento. Este trabajo aborda la estimación de las propiedades petrofísicas dinámicas de muestras de roca del horizonte productor mediante el uso de Tomografía Computarizada (acorde a sus siglas en inglés CT). Para esto se propone un conjunto de cinco algoritmos numéricos para la estimación de la porosidad efectiva, saturación, frente de avance, volumen atrapado y factor de recobro durante el desplazamiento de dos líquidos, crudo y agua, en el interior del medio poroso. El objetivo de la caracterización dinámica, mediante CT, es comprender y analizar los parámetros que influyen en el éxito de un desplazamiento de crudo en un medio poroso como parte de un esquema de producción mejorado en yacimientos maduros y de crudo pesado

Validation of current body composition estimation equations for men over 60 years of age

This study compared five skinfold equations for body composition (Jackson & Pollock\u27s Sum of 7 {dollar}\{{dollar}JP7{dollar}\}{dollar} and Sum of 3 {dollar}\{{dollar}JP3{dollar}\}{dollar}; Jackson & Pollock\u27s Sum of 4 {dollar}\{{dollar}Y4{dollar}\}{dollar} and Sum of 3 {dollar}\{{dollar}Y3{dollar}\}{dollar} for the YMCA, and Durnin and Womersley\u27s Sum of 7 {dollar}\{{dollar}DW{dollar}\}){dollar} with percent fat obtained from underwater weighing. Subjects were ninety-seven adult males aged 60-80 years. Skinfold measurements were taken with Lange calipers and underwater weight (UWW) was determined in a seated position utilizing a load cell system with residual volume (RV) measured at the time of weighing; The skinfold equations achieved a mean correlation of.74 with underwater weighing. JP7 yielded the highest correlation (.78) and DW the lowest (.72). A 1RM-ANOVA indicated that all five equations produced significantly different results than UWW. The data showed that these equations are not as valid with the present study\u27s population as with those from which the equations were derived

Body mass index in young Dutch adults : its development and the etiology of its development

Follow-up studies of long duration have shown a U-shaped relationship between mortality/morbidity and the body mass index (BMI, weight/height 2). The risk to health posed by obesity appears to be larger in younger subjects than in older subjects. Though this might suggest that a moderate weight gain after the termination of growth may not increase the risk to health, this contention is not supported by other observations (Chapter 1). These are: (1) the range of relative weight associated with minim= mortality does not seem to shift to higher values with increasing age, at least not in men. (2) Diseases associated with overweight at younger ages need not be the same as those associated with overweight at older ages. (3) Cohort effects may bias the age trend in the risk associated with overweight. (4) Longitudinal studies on adults show that changes in body weight are associated with changes in risk factors of diseases. (5) Anthropometric studies show that even at the same weight, the fat mass increases with increasing age. In addition, several studies suggest that weight gained during adulthood mainly accumulates in the abdomen, which means a shift to a fat distribution more strongly associated with risk to health. The risk to health therefore does not seem to remain constant if body weight increases during adulthood.As part of an extensive mixed-longitudinal study (Chapter 2), this thesis deals with the development of the BMI and the etiology of this development in young adults. In addition, one methodological study is described. These studies build m cross-sectional observations that were made in the first examination of the study.In spring 1980, all residents of Dutch nationality in the county of Ede, born in 1948-1950, 1953-1955, 1958-1960 were invited by mail to participate in the study. Participants in spring 1980 (N=3936) were followed for four years (1980-1984) in two groups, the follow-up group (N=1670) and the control group (N=2266). From spring 1981 onward the follow-up group was approached twice a year in seven consecutive examinations. The control group was re-measured in spring 1984 only. At each examination a questionnaire was completed and body weight in light indoor clothing and without shoes was measured to the nearest 0.5 kg. Body height was measured to the nearest 0.1 cm in spring 1980. Subgroups of the follow-up and control groups were additionally examined for the studies described in Chapter 7 and 8.The development of the BMI is dealt with in Chapter 3, in which the mixed-longitudinal design of the study was utilized, and Chapter 4, in which the data were analyzed longitudinally. Over the four years, the change in BMI of the follow-up group was the same as that of the control group. Prom 19 to 35 years of age the median BMI increased from 22.1 kg/m 2to 24.4 kg/m 2in men and from 21.1 kg/m 2to 23.0 kg/m 2in women (Chapter 3). This increment in BMI gave rise to an incidence of moderate overweight (BMI>25 kg/m 2) which increased from 4.8% per 4 years to 15.5% per 4 years in men, and was more stable (5.3-5.7% per 4 years) in women (Chapter 4). Thus, especially in men, young adulthood appears to be a critical period for the development of overweight.The age-reference curves (Chapter 3) suggested that the variation of the BMI over subjects was independent of age. In accordance, the longitudinal analyses showed that the initial BMI and the rate of gain in BMI were unrelated in men and only slightly negatively related in women. Thus, overweight subjects did not appear to gain more or less body mass than non-overweight subjects.The within-subjects standard deviation of the yearly measured BMI was 0.69 kg/m 2in men and 0.74 kg/m 2in women (Chaper 4). This fluctuation was larger in overweight subjects than in normal-weight subjects and was larger in subjects with a larger long-term change (gain or loss) in BMI than in subjects who had a more stable BMI. The considerable fluctuation in BMI may mask the gradual long-term increment in BMI and may thus hinder young adults from being aware that they are becoming overweight.The effect of dieting is dealt with in Chapter 5. After two years of follow-up, the average decrease in body mass as a result of dieting was -0.5 kg/m 2(95% confidence interval (CI):-1.0,+0.0) in men and -0.4 kg/m 2(95%CI:-0.8,+0.0) in women. This approximately amounts to an average weight reduction of 1.5 kg in men and 1.0 kg in women. The effect of dieting was most pronounced in men whose initial BMI was high, who dieted during the summer, or who dieted more frequently, and in women who were older than 30 or who dieted on medical advice. Though subjects who have already developed severe overweight may achieve a larger reduction in the risk to health by losing the same amount of body mass as subjects who are only moderately overweight, it is unlikely that the benefit is large unless they persist. However, the effect of dieting may be enough to prevent the age-related gain in body mass and thus dieting may especially play a part in the prevention of overweight.Chapter 6 deals with the changes in BMI in relation to number of life events experienced. During the first year of follow-up several subgroups of men and women who experienced many life events and several subgroups of men who experienced few life events showed a gain in body mass. After another year of follow-up this gain in body mass had disappeared in almost all subgroups; compared with dieting ran with an intermediate number of life events, dieting men with few life events gained +1.3 kg/m 2(95%CI:+0.0,+2.6) more body mass, whereas dieting men with many life events gained +1.8 kg/m 2(95%CI: +0.5,+3.0) more body mass. Thus, life events seem to have an impact on the etiology of overweight in men.One life event in women is considered more specifically (Chapter 7); i.e. pregnancy. Women who breastfed their child for more than two months gained more body mass than was expected from aging. Nine months postpartum they were +0.6 kg/m 2(90%CI: +0.1,+1.0) heavier than expected. This difference was slightly smaller (not significantly) in women who breastfed their child for 0-2 months. Women who used bromocriptine to stop lactation lost body mass unexpectedly.In a methodological study (Chapter 8) the impact of adjustment of the BMI for body diameters (i.e. knee, wrist, elbow, shoulder, pelvis and hip) on the prediction of body fatness was examined. In addition to what was explained by the BMI, 6% of the variation in body fatness was explained by the shoulder diameter in men, and also 6% by the knee diameter in women. This improvement in estimating body fatness by the diameters, used as continuous variables, was considered too small to justify frame categories being included in weight-height tables. Instead of frame size, fat distribution might be a more useful attribute in these tables.In the last chapter (Chapter 9) several aspects relating to the validity of the mixed-longitudinal study are discussed. The main conclusions of this thesis are:- Young adulthood seems to be a critical period in the development of moderate overweight, expecially in men.- The age-related gain in BMI of overweight young adults and of young adults of normal weight is similar.- Overweight subjects are unlikely to decrease their risk to health markedly by dieting as generally practiced, unless they persist. Dieting may be more effective in preventing overweight.- The experience of many life events may play a part in the etiology of overweight in men, as does the experience of few life events.- Women who breastfeed their child for more than two months may gain more body mass than expected from aging. - In weight-height tables the fat distribution might be a more useful attribute than frame size categories.</TT

The Use of Ultrasound in the Assessment of Canine Obesity

The aim of the studies reported in this thesis was to evaluate the use of ultrasound in the assessment of canine obesity

The Association of Multiple Gene Variants with Ageing Skeletal Muscle Phenotypes in Elderly Women

There is a scarcity of studies that have investigated the role of multiple single nucleotide polymorphisms (SNPs) on a range of muscle phenotypes in an elderly population. The present study investigated the possible association of 24 SNPs with skeletal muscle phenotypes in 307 elderly Caucasian women (aged 60–91 years, 66.3 ± 11.3 kg). Skeletal muscle phenotypes included biceps brachii thickness, vastus lateralis cross-sectional areas, maximal hand grip strength, isometric knee extension and elbow flexion torque. Genotyping for 24 SNPs, chosen on their skeletal muscle structural or functional links, was conducted on DNA extracted from blood or saliva. Of the 24 SNPs, 10 were associated with at least one skeletal muscle phenotype. HIF1A rs11549465 was associated with three skeletal muscle phenotypes and PTK2 rs7460 and ACVR1B rs10783485 were each associated with two phenotypes. PTK2 rs7843014, COL1A1 rs1800012, CNTF rs1800169, NOS3 rs1799983, MSTN rs1805086, TRHR rs7832552 and FTO rs9939609 were each associated with one. Elderly women possessing favourable genotypes were 3.6–13.2% stronger and had 4.6–14.7% larger muscle than those with less favourable genotypes. These associations, together with future work involving a broader range of SNPs, may help identify individuals at particular risk of an age-associated loss of independence.</jats:p