Association of the metabolic syndrome with history of myocardial infarction and stroke in the Third National Health and Nutrition Examination Survey.
(1/2357)
BACKGROUND: The combination of cardiovascular risk factors known as the metabolic syndrome is receiving increased attention from physicians, but data on the syndrome's association with morbidity are limited. METHODS AND RESULTS: Applying National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria, we evaluated 10 357 NHANES III subjects for the 5 component conditions of the metabolic syndrome: insulin resistance, abdominal obesity based on waist circumference, hypertriglyceridemia, low HDL cholesterol (HDL-C), and hypertension, as well as the full syndrome, defined as at least 3 of the 5 conditions. Logistic regression was used to estimate the cross-sectional association of the syndrome and each of its 5 component conditions separately with history of myocardial infarction (MI), stroke, and either MI or stroke (MI/stroke). Models were adjusted for age, sex, race, and cigarette smoking. The metabolic syndrome was significantly related in multivariate analysis to MI (OR, 2.01; 95% CI, 1.53 to 2.64), stroke (OR, 2.16; 95% CI, 1.48 to 3.16), and MI/stroke (OR, 2.05; 95% CI, 1.64 to 2.57). The syndrome was significantly associated with MI/stroke in both women and men. Among the component conditions, insulin resistance (OR, 1.30; 95% CI, 1.03 to 1.66), low HDL-C (OR, 1.35; 95% CI, 1.05 to 1.74), hypertension (OR, 1.44; 95% CI, 1.00 to 2.08), and hypertriglyceridemia (OR, 1.66; 95% CI=1.20 to 2.30) were independently and significantly related to MI/stroke. CONCLUSIONS: These results indicate a strong, consistent relationship of the metabolic syndrome with prevalent MI and stroke. (+info)
Genetic dissection of mammalian Cdc7 kinase: cell cycle and developmental roles.
(2/2357)
Cdc7, originally discovered by Hartwell as a budding yeast mutant that arrests immediately before the onset of S phase, is conserved through evolution and plays essential roles in initiation of mitotic DNA replication. Inducible inactivation of Cdc7 in mouse embryonic stem cells leads to rapid cessation of DNA synthesis and the subsequent activation of checkpoint responses, resulting in p53 activation and eventually p53-mediated apoptosis. This indicates a requirement of Cdc7 kinase for ongoing replication of mammalian genomes, and loss of Cdc7 kinase presumably generates arrested replication fork signals. Cdc7-/- mice or embryonic fibroblast cells (MEFs) expressing a low level of transgene-encoded Cdc7 protein are viable but exhibit reduced body size with impaired germ cell development and decreased cell proliferation. Interestingly, these phenotypes are largely corrected by the presence of an additional copy of the transgene, resulting in increased level of Cdc7 expression. This indicates the requirement of a critical level of Cdc7 for normal cell proliferation and development of specific organs. These results from mammals will be discussed in conjunction with the pleiotropic effects of Cdc7 mutation observed in yeasts. (+info)
Effect of body size on breathing pattern and fine-particle deposition in children.
(3/2357)
Interchild variability in breathing patterns may contribute to variability in fine particle lung deposition and morbidity in children associated with those particles. Fractional deposition (DF) of fine particles (2-microm monodisperse, carnauba wax particles) was measured in healthy children, age 6-13 yr (n = 36), while they followed a resting breathing pattern previously determined by respiratory inductance plethysmography. Interchild variation in DF, measured by photometry at the mouth, was most strongly predicted by their tidal volume (Vt) (r =0.79, P < 0.001). Multiple regression analysis further showed that, for any given height and age, Vt increased with increasing body mass index (BMI) (P < 0.001). The overweight children (> or =95th percentile BMI) (n = 8) had twice the DF of those in the lowest BMI quartile (<25th percentile) (n = 9; 0.28 +/- 0.13 vs. 0.15 +/- 0.06, respectively; P < 0.02). In the same groups, resting minute ventilation was also significantly higher in the overweight children (8.5 +/- 2.2 vs. 5.9 +/- 1.1 l/min; P < 0.01). Consequently, the rate of deposition (i.e., particles depositing/time) in the overweight children was 2.8 times that of the leanest children (P < 0.02). Among all children, the rate of deposition was significantly correlated with BMI (r = 0.46, P = 0.004). These results suggest that increased weight in children may be associated with increased risk from inhalation of pollutant particles in ambient air. (+info)
Developmental allometry of pulmonary structure and function in the altricial Australian pelican Pelecanus conspicillatus.
(4/2357)
Quantitative methods have been used to correlate maximal oxygen uptake with lung development in Australian pelicans. These birds produce the largest altricial neonates and become some of the largest birds capable of flight. During post-hatching growth to adults, body mass increases by two orders of magnitude (from 88 g to 8.8 kg). Oxygen consumption rates were measured at rest and during exposure to cold and during exercise. Then the lungs were quantitatively assessed using morphometric techniques. Allometric relationships between body mass (M) and gas exchange parameters (Y) were determined and evaluated by examining the exponents of the equation Y=aM(b). This intraspecific study was compared to interspecific studies of adult birds reported in the literature. Total lung volume scales similarly in juvenile pelicans (b=1.05) as in adult birds (b=1.02). However, surface area of the blood-gas barrier greatly increases (b=1.25), and its harmonic mean thickness does not significantly change (b=0.02), in comparison to exponents from adult birds (b=0.86 and 0.07, respectively). As a result, the diffusing capacity of the blood-gas tissue barrier increases much more during development (b=1.23) than it does in adult birds of different sizes (b=0.79). It increases in parallel to maximal oxygen consumption rate (b=1.28), suggesting that the gas exchange system is either limited by lung development or possibly symmorphic. The capacity of the oxygen delivery system is theoretically sufficient for powered flight well in advance of the bird's need to use it. (+info)
Phenotypic relationships between longevity, type traits, and production in Chianina beef cattle.
(5/2357)
Longevity is an increasingly important trait in beef cattle. Increased longevity decreases costs for the farmer and increases revenue. The objective of this research was to investigate the phenotypic relationship between type traits and longevity in Chianina beef cattle, and the relationship between production and longevity, to analyze the effect of voluntary culling. Data included records on reproductive, productive, and type traits provided by the National Association of Italian Beef Cattle Breeders from 6,395 Chianina cows. The average length of productive life was 1,829 d. The herd-year had a strong effect on the risk of culling. The effects of 22 type traits were analyzed. All the muscularity traits analyzed were highly significant (P < 0.01) and as a group had the largest effect on longevity, followed by dimension, refinement, and leg traits. Cows that calved before 35 mo of age had a lower probability of being culled than cows calving after 35 mo of age. Variation in herd size had a strong effect on risk ratio, with lower risk for intermediate classes. Cows with approximately one calf per year remained in the herd longer than did cows with fewer calves. Straight-legged animals had a 59% greater probability of being replaced than cows with a moderate angle to the hock, whereas sickle-legged animals had only a 3% higher probability of being culled than average cows. Udder conformation had no effect on longevity. In summary, results of this study indicate that herd-year effects and muscularity traits were the most important factors for longevity for Chianina cows among the factors studied. (+info)
A prospective study of body size in different periods of life and risk of premenopausal breast cancer.
(6/2357)
The prevalence of obesity at all ages is increasing epidemically worldwide. Information on the association between premenopausal breast cancer and body size during childhood and teenage years is scarce. In 1991 to 1992, a prospective cohort study was assembled in Norway and Sweden. We included in the analysis presented here 99,717 premenopausal women. During the follow-up period, which ended in December 1999, 733 of these women developed a primary invasive breast cancer. Overweight and obesity [body mass index (BMI) > 25 kg/m(2)] at enrollment was associated with a decreased risk of premenopausal breast cancer (P for linear trend = 0.007). Apparent associations between perceived body shape at age 7 and BMI at age 18, with heavier builds at both ages seemingly being protective for premenopausal breast cancer risk, lost their statistical significance after adjustment for BMI at cohort enrollment. Body size at age 7 was correlated with BMI at age 18 (r = 0.43); BMI at age 18 was correlated with adult BMI (r = 0.48). Changes in body size from age 7 or 18 to adulthood did not affect per se risk of premenopausal breast cancer risk. Height was related to risk, with a statistically significantly 30% reduced risk only in women shorter than 160 cm as compared with taller ones. The decreased risk of premenopausal breast cancer was observed in overweight and obese women without, but not in those with, a family history of breast cancer. (+info)
Microsmatic primates: reconsidering how and when size matters.
(7/2357)
The terms "microsmatic" and "macrosmatic" refer to species with lesser or greater levels, respectively, of olfactory function. Historically, primates are considered microsmats (olfactory sense reduced) with a concomitant increased emphasis on vision. The olfactory bulbs (forebrain centers that receive peripheral olfactory input) are proportionately smaller in primates compared to most other mammals. Similarly, the regions of the nasal cavity that are covered with olfactory epithelium (containing receptor cells) have proportionately less surface area in primates than other mammals. Thus, the generalization that primates are microsmatic is most frequently stated in terms of the proportional rather than absolute size of olfactory structures. Yet the importance of scaling to body size is unclear in regard to the chemical senses such as the olfactory or vomeronasal systems-do chemosensory structures such as olfactory bulbs and olfactory epithelium exhibit the same neural relationship to body mass that is seen for neural tissues that supply innervation to musculature or the skin? Previous studies examining neuronal density, volume, and/or surface area of the olfactory epithelium illustrate that different conclusions may be supported based on the parameter used. Plots of olfactory bulb volume versus body mass that generated for large-scale taxonomic studies or growth studies benefit from body mass (or total brain volume) with a comparative perspective. However, our examination of proportional versus absolute measurements implies that in comparisons within taxa, body size adjustments needlessly distort the data. As a final consideration, another embryonic derivative of the nasal placode, the vomeronasal organ, may warrant consideration regarding a definition of microsomia versus macrosomia. (+info)
The genetic covariance among clinal environments after adaptation to an environmental gradient in Drosophila serrata.
(8/2357)
We examined the genetic basis of clinal adaptation by determining the evolutionary response of life-history traits to laboratory natural selection along a gradient of thermal stress in Drosophila serrata. A gradient of heat stress was created by exposing larvae to a heat stress of 36 degrees for 4 hr for 0, 1, 2, 3, 4, or 5 days of larval development, with the remainder of development taking place at 25 degrees. Replicated lines were exposed to each level of this stress every second generation for 30 generations. At the end of selection, we conducted a complete reciprocal transfer experiment where all populations were raised in all environments, to estimate the realized additive genetic covariance matrix among clinal environments in three life-history traits. Visualization of the genetic covariance functions of the life-history traits revealed that the genetic correlation between environments generally declined as environments became more different and even became negative between the most different environments in some cases. One exception to this general pattern was a life-history trait representing the classic trade-off between development time and body size, which responded to selection in a similar genetic fashion across all environments. Adaptation to clinal environments may involve a number of distinct genetic effects along the length of the cline, the complexity of which may not be fully revealed by focusing primarily on populations at the ends of the cline. (+info)