Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Allometry”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources
PubMed1991

Deposition and distribution of carcass fat for steers differing in frame size and muscle thickness.

Yearling feeder steers (n = 324) representing nine frame size (Large, Medium, Small) x muscle thickness (No. 1, No. 2, No. 3) subclasses were serially slaughtered at 28-d intervals during a 140-d finishing period. Weights for total dissectible (TDF) and subcutaneous fat (SQ) from each of nine wholesale cuts were recorded. Resulting data were analyzed using allometry (Y = aXb and Y = aXb10cx) to characterize deposition patterns for fat and to determine effects of feeder cattle frame size (F) and muscle thickness (M) on relative fat deposition and distribution. Patterns of TDF and SQ deposition were similar among cuts. As the steers became fatter, relative proportions of TDF and SQ in the abdominal and dorsal regions of the carcass increased and relative proportions of fat in the distal regions decreased. There was a tendency for the growth impetus of TDF and SQ to shift from the ventral portions of the carcass toward the dorsal region of the carcass as fattening progressed. Despite significant among-class differences in allometric coefficients, relative proportions of TDF and SQ in the nine wholesale cuts were remarkably similar for all nine F x M subclasses when compared at a constant percentage of total carcass fat. At endpoints of either a constant fat thickness measurement or a constant USDA marbling score, subclass differences in fat distribution were negligible.

Adipose Tissue↗
PubMed1986

Effect of age, weaning and diet on digestive enzyme levels in the piglet.

Thirty-seven pigs were used to evaluate the effects of age and weaning on the level of protease in the gastric mucosa and trypsin, chymotrypsin, amylase and lipase in the pancreas. There was a positive allometry of the pancreas and gastric mucosa associated with age and with weaning to a solid diet. Increases with age in total activity of chymotrypsin, trypsin, amylase and gastric proteases were due to increases in both tissue weight and enzyme activity per gram of tissue. A general depression in pancreatic enzymatic activities, but not in gastric proteolytic activity, was found during the first week following weaning. Forty pigs were used in a second trial to evaluate the effects of age and weaning diet on the same digestive enzymes. Total activity of all enzymes assayed increased with time postweaning. Increases in total activity of lipase and chymotrypsin were due primarily to increased pancreatic weight postweaning. Amylase, trypsin and gastric protease increases were due both to increased tissue weight and increased activity per gram of tissue. There were no effects of diet on the weight of gastric mucosa or the level of activity of the gastric proteases. Pigs fed a diet containing 20% whey had larger pancreases (P less than .10) at slaughter and a greater, but nonsignificant, mean activity per gram of pancreas for all pancreatic enzymes. It appears that the pig has sufficient pancreatic and gastric enzyme activity so that performance should not be limited, with the possible exception of the period shortly after weaning. However diet digestibility and subsequent pig performance may be more directly related to the extent of release of these enzymes into the intestine and the conditions that exist therein.

Aging↗
PubMed1989

Main long bones of limbs of the Jomon people--proportions in their lengths.

The proportional relationships among the lengths of main limb bones comprising the humerus, radius, tibia and femur of the Jomon people are examined by means of comparison with those of the Kofun and recent Japanese. The disto-proximal indices (the radio-humeral and tibiofemoral) of the Jomon are significantly greater than those of the comparison ages, but the humero-femoral index, as a intermembral, is significantly smaller. Logarithmic plots showing the relation between each two bones, indicate no significant age differences among the inclinations of regression lines corresponding to allometry coefficients. However, significant age differences among the levels of lines were found. According to previous studies, there may be two factors affecting the proportions among limb segments, one biomechanical and the other thermal. The adaptation to mode of life, such as hunting of quick moving animals, appears to be a more reasonable interpretation of the relatively long distal segments (high disto-proximal indices) of the Jomon people.

Adolescent↗
PubMed2006

Assessment of brown adipose tissue activity in rats by 99mTc-sestamibi uptake.

Brown adipose tissue (BAT) physiology and imaging have recently attracted considerable attention. BAT is characterized both by enhanced perfusion and increased mitochondrial activity. (99m)Tc-sestamibi is a lipophilic cationic tracer that concentrates in mitochondria. Data on the accumulation of (99m)Tc-sestamibi in BAT are currently lacking. This study investigates the in vivo (99m)Tc-sestamibi uptake in rat BAT. (99m)Tc-sestamibi was administered in male Wistar rats of various age and body size. (99m)Tc-sestamibi uptake was measured in vitro in BAT and white fat (WF) together with cytochrome c oxidase activity. Both (99m)Tc-sestamibi uptake and cytochrome c oxidase activity were higher in BAT than in WF (P<0.05). (99m)Tc-Sestamibi uptake in both BAT and WF was negatively related to body weight (r = -0.96 and -0.89, respectively) as was the BAT/WF uptake ratio (r = -0.85). These data show a higher (99m)Tc-sestamibi uptake in BAT compared to WF, in agreement with the high mitochondrial content and respiratory activity of the former. The strong negative correlation between (99m)Tc-sestamibi uptake in BAT and body weight (negative allometry), is in accordance to increased needs of thermogenesis in smaller animals. Implications of increased (99m)Tc-sestamibi uptake in BAT in radionuclide imaging are also discussed.

Adipose Tissue, Brown↗
PubMedDate not supplied

Components of soft tissue deformations in subjects with untreated angle's Class III malocclusions: thin-plate spline analysis.

While the dynamics of maxillo-mandibular allometry associated with treatment modalities available for the management of Class III malocclusions currently are under investigation, developmental aberration of the soft tissues in untreated Class III malocclusions requires specification. In this study, lateral cephalographs of 124 prepubertal European-American children (71 with untreated Class III malocclusion; 53 with Class I occlusion) were traced, and 12 soft-tissue landmarks digitized. Resultant geometries were scaled to an equivalent size and mean Class III and Class I configurations compared. Procrustes analysis established statistical difference (P < 0.001) between the mean configurations. Comparing the overall untreated Class III and Class I configurations, thin-plate spline (TPS) analysis indicated that both affine and non-affine transformations contribute towards the deformation (total spline) of the averaged Class III soft tissue configuration. For non-affine transformations, partial warp 8 had the highest magnitude, indicating large-scale deformations visualized as a combination of columellar retrusion and lower labial protrusion. In addition, partial warp 5 also had a high magnitude, demonstrating upper labial vertical compression with antero-inferior elongation of the lower labio-mental soft tissue complex. Thus, children with Class III malocclusions demonstrate antero-posterior and vertical deformations of the maxillary soft tissue complex in combination with antero-inferior mandibular soft tissue elongation. This pattern of deformations may represent gene-environment interactions, resulting in Class III malocclusions with characteristic phenotypes, that are amenable to orthodontic and dentofacial orthopedic manipulations.

Age Factors↗
PubMed1976

A phenomenological approach to the growth of the winter stonefly, Taeniopteryx nivalis (Fitch) (Plecoptera:Taeniopterygidae).

The growth and respiration of a univoltine winter stonefly, Taeniopteryx nivalis (Fitch) was evaluated over a period which encompassed both the nymphal and adult life stages. A simple allometry did not describe the relation found between weight and respiration during the evaluated growth period. The relation between growth and respiration of T. nivalis was described by an extension of the stochastic growth model of Zotina and Zotin, which enables one to determine the biological age of an organism by utilizing only weight and respiration. From a comparison of the general Bertalanffy growth model with the extended stochastic model, the growth of T. nivalis up to the last instar could be ascribed entirely to anabolic processes; differentiation probably accounts for the observed relation between weight and respiration during the last nymphal instar.

Animals↗
PubMed1976

[Study of correlations linking the volumes of the hypophyseal lobes and the epiphysis to body and brain weights in Chiroptera].

Study of the correlations binding the different lobes of the hypophysis and the pineal gland to body weight and brain weight in Chiroptera shows that the hypophysis is better correlated to body and brain weight than the pineal gland, fact that we already observed in Rodents and Primates. The allometry coefficient (M.R.A.) related to body weight varies from 0,80 to 0,98 for the hypophyseal lobes. The value of this coefficient for the pineal gland (1,60) is greater than that found (1,009) in another group of Mammals (Insectivora, Lemurians and Primates). It is less sure as the important variations in volume of this gland determine a lower correlation coefficient.

Animals↗
PubMed1999

Changes in the factor of safety within the superstructure of a dicot tree.

The objective of this study was to determine whether the factor of safety for mechanical stability varied among stems differing in size and age within the superstructure of a large dicot tree. Two factors of safety were selected for study: the quotient of the critical buckling height and the actual length of stems, Hcrit/L, and the quotient of the modulus of rupture (the force per unit area required to break a stem) and the working stress (the force per unit area resulting from the biomass measured distal to a stem), M(R)/σ(w). These two dimensionless safety factors were determined for a total of 420 shoot segments comprising much of the aboveground biomass of a Robinia pseudoacacia (Fabaceae) tree measuring 18.7 m in height and 1347 kg in mass, and 0.46 m in diameter (40 yr old) at 1.2 m from the ground.An S-shaped trend was observed when each of the two factors of safety was plotted as a function of stem age. Each factor decreased from a local maximum for the most distal (peripheral) stems in the canopy to a local minimum value for stems ∼10 yr old; each factor increased again to another local maximum for stems 11-18 yr old, and then decreased steadily toward the base of the trunk. This trend was the result of the allometric relationships among stem diameter, length, biomass, and material properties (stiffness and strength) with respect to stem age. Although they were disproportionately more slender than their older counterparts, peripheral stems were sufficiently stiff and strong to sustain the stresses resulting from their weight and that of foliage without deflecting under these loads, yet they were sufficiently flexible to easily bend and thereby presumably provide a mechanism to reduce the drag forces acting on the entire tree. In contrast, the internally imposed mechanical forces acting on progressively older stems increased at a greater rate than the observed rate of increase in stem stiffness, strength, or diameter. The probability of mechanical failure, which must be considered from a demographic perspective (i.e., an age-dependent phenomenon), thus increased from older branches to the base of the trunk. Reports of similar allometric trends based on interspecific comparisons among diverse dicot species comply with the allometry observed for the R. pseudoacacia tree and suggest that the S-shaped trend for the factor of safety holds for stems differing in age drawn from individual trees and for the trunks of conspecifics differing in age drawn from a dense population.

Journal Article↗
PubMed1999

Preclinical pharmacokinetics and interspecies scaling of a novel vitronectin receptor antagonist.

Allometric scaling may be used in drug development to predict the pharmacokinetics of xenobiotics in humans from animal data. Although allometry may be successful for compounds that are excreted unchanged or that are oxidatively metabolized (with corrections for metabolic capacity), it has been more challenging for compounds excreted primarily as conjugates in bile. (S)-10, 11-Dihydro-3-[3-(pyridin-2-ylamino)-1-propyloxy]-5H-dibenzo[ a, d]cycloheptene-10-acetic acid (SB-265123) is a novel alphavbeta3 ("vitronectin receptor") antagonist. In this study, the in vivo pharmacokinetics and in vitro plasma protein binding of SB-265123 were examined in four species: mice, rats, dogs, and monkeys. In monkeys and dogs, SB-265123 exhibited moderate clearance, whereas low clearance (<20% hepatic blood flow) was observed in the rat, and high clearance (>70% hepatic blood flow) was seen in the mouse. The concentration-time profiles indicated the possibility of enterohepatic recirculation; subsequent studies in bile duct-cannulated rats demonstrated extensive biliary excretion of an acyl-glucuronide of SB-265123. In allometric scaling to predict the disposition of SB-265123 in humans, various standard correction factors were applied, including protein binding, maximum lifespan potential, and brain weight; each failed to produce adequate interspecies scaling of clearance (r(2) < 0.72). Consequently, a novel correction factor incorporating bile flow and microsomal UDP-glucuronosyltransferase activity in each species was applied, demonstrating substantial improvement in the correlation of the allometric plot (r(2) = 0.96). This study demonstrates a novel allometric correction that may be applicable to compounds that undergo conjugation and biliary excretion.

Acetates↗
PubMed1999

Morphometry of the mandible in prepubertal craniofacial microsomia patients following an inverted L osteotomy.

The aim of this study was to undertake finite element modeling of craniofacial microsomia (CFM) patients who exhibited a unilateral mandibular deformity that was surgically corrected by an inverted L osteotomy and autogenous bone graft. Preoperative, 1-year, and 3-year postoperative anteroposterior cephalographs of 14 consecutive children (mean age, about 9 years) with CFM were employed. All cephalographs were scanned, and 8 homologous mandibular landmarks were digitized in triplicate (digitization error < 1%; P > 0.05). Average mandibular geometries, scaled to an equivalent size, were generated using Procrustes superimposition and subjected to analysis of variance. Results showed that while the mean pre- and early postoperative mandibular configurations marginally failed to differ statistically, finite element modeling of the affected mandibular ramus showed a positive allometry (a lengthening by about 10% to 12%) and marked anisotropy, presumably reflecting the surgical procedure carried out in that region. For the preoperative and late postoperative means, the configurations were statistically different (P < 0.002), showing a lengthening of the ramus (about 14%) while the unoperated side had a high degree of isotropy. The early and late postoperative configurations were also statistically different (P < 0.002). The operated ramus showed an increase in length (about 15%), but the corpus showed a decrease in size (about 10%) and marked anisotropy that reflected remodeling associated with the surgical procedure. Although mandibular morphology is improved in CFM patients who are surgically treated by an inverted L osteotomy, some relapse is evident due to deficient growth, localized in the mandibular ramus and body of the affected side.

Analysis of Variance↗
PubMed2000

Longitudinal and allometric variation in indicators of muscle metabolic capacities in atlantic cod (Gadus morrhua).

This study evaluated whether indicators of metabolic capacity of cod white muscle differ along the length of the body, whether this variation persists over a large range of body sizes, and whether the allometry of metabolic capacities is similar along the length of the body. We examined the maximal activities of two glycolytic enzymes, phosphofructokinase (PFK) and lactate dehydrogenase (LDH), a mitochondrial enzyme, cytochrome C oxidase (CCO), and the biosynthetic enzyme nucleotide diphosphate kinase (NDPK). All enzymes examined showed significant size dependence, which was generally apparent in all regions. The activity of glycolytic enzymes increased with size, whereas that of CCO and NDPK decreased with size. For PFK and LDH, the size dependence decreased caudally, whereas for CCO and NDPK it was strongest in the caudal sample. For each size range, the activities of PFK, LDH, and CCO were higher in the last third of the body than in the middle or just behind the head. In contrast, NDPK activity was higher just behind the head than at the middle or in the last third of the body, suggesting that nuclear proliferation is more rapid in this zone. The high capacity for adenosine triphosphate (ATP) generation in the caudal region suggests that increases in mass-specific ATP output are advantageous in this relatively thin section of the body.

Animals↗
PubMed2000

Scaling properties of the frontal sinus in the African great apes--a clue to the role of the human paranasal sinuses.

The biology of scaling (allometry) can prove a useful tool in comparative anatomical studies. Amongst primates only the African Great Apes and Man possess a frontal sinus. The aim of this study was to identify the allometric properties of the frontal sinus in order to gain clues as to the role of the human paranasal sinuses. A measure of frontal sinus volume was calculated for fifty-seven Great Apes and then scaled against indicators of body size and nasal cavity volume. The results suggest that there are racial variations in frontal sinus size in the African Great Ape populations. This phenomenon mirrors the human condition. The scaling relationships identified in the study lend support to the hypothesis that the frontal sinus has a "structural" rather than a "functional" role.

Animals↗
PubMed2001

The power of size. 2. Rate constants and equilibrium ratios for accumulation of inorganic substances related to species weight.

Most of the thousands of substances and species that risk assessment has to deal with are not investigated empirically because of financial, practical, and ethical constraints. To facilitate extrapolation, we have developed a model for concentration kinetics of inorganic substances as a function of the exposure concentration of the chemical and the weight and trophic level of the species. The ecological parameters and the resistances that substances encounter during diffusion in water layers were obtained from previous reviews. The other chemical parameters (the resistances for permeation of lipid layers) were calibrated in the present study on 1,062 rate constants for absorption from water, for assimilation from food, and for elimination. Data on all elements and species were collected, but most applied to aquatic species, in particular mollusks and fish, and to transition metals, in particular group IIB (Zn, Cd, Hg). Their ratio was validated on 92 regressions and nine geometric averages, representing thousands of (near-)equilibrium accumulation ratios from laboratory and field studies. Rate constants for absorption and elimination decreased with species weight at an exponent of about -0.25, known from ecological allometry. On average, uptake-rate constants decreased with about the reciprocal square root of the exposure concentration. About 71 and 30% of the variation in absorption and elimination was explained by the model, respectively. The efficiency for assimilation of elements from food appeared to be determined mainly by the food digestibility and the distribution over egested and digested fractions. (Near-)equilibrium accumulation and magnification ratios also decreased with the reciprocal square root of the exposure concentration. The level of the organism-solids concentrations ratios roughly varied between one and two orders of magnitude, depending on the number of elements and species groups investigated. Metal concentrations did not increase at higher trophic levels, with the exception of (methyl-)mercury. Organism-solids concentration ratios for terrestrial species tended to be somewhat lower than those for their aquatic equivalents. Food web accumulation, expressed as organism-organic solids and organism-food concentrations ratios, can therefore be only partly explained by ecological variables. The model is believed to facilitate various types of scientific interpretation as well as environmental risk assessment.

Absorption↗
PubMed2001

Stature, maturation variation and secular trends in forensic anthropology.

A twentieth-century trend for increased stature has received considerable attention in the forensic literature with regard to its effects on stature estimation, but a secular trend for earlier maturation has received little attention. Current evidence indicates that within populations with similar climatic adaptation, truncation or extension of the same trajectory of ontogenetic allometry accounts for the secular trend and the within-cohort stature variation, as well as the scaling of limb proportion to stature and intralimb proportions. Since secular increase is small compared to interindividual variation, the Trotter and Gleser formulae are still appropriate as long as the 95% confidence intervals are applied. A secular trend for increasing childhood and adolescent obesity is associated with a trend for accelerated skeletal maturation, but does not predict a consistent direction or a quantitative correction for traditional standards. Secular trends for increased stature and earlier maturation are overshadowed by increasing nonsecular intrapopulational variation.

Adolescent↗
PubMed1975

A canonical discriminant analysis of post-embryonic development in Notonecta Maculata fabricius (Insecta:Heteroptera).

A multivariate method, canonical discriminant analysis, was used to discern a pattern of growth in Notonecta maculata. A stepwise procedure reduced the 11 metrical characters measured on individuals of both sexes, from the 1st larval stage to the adult, to 4 significant variates which were used in the canonical analysis. The four canonical variates accounted for the meaningful part of the variablity. Relying on bivariate allometry and on an experimentation with a juvenile hormone analogue, each independent direction of variation was related to combined effects of such biological factors as a general growth trend, sex and juvenile hormone.

Analysis of Variance↗
PubMed2002

New formulae for estimating stature in the Balkans.

Recent studies of secular change and allometry have observed differential limb proportions between the sexes, among and within populations. These studies suggest that stature prediction formulae developed from American Whites may be inappropriate for European populations. The purpose of this investigation is to present more appropriate stature prediction equations for use in the Balkans to aid present-day identifications of the victims of genocide. The reference sample totals 545 white males obtained from World War II data. The Eastern European sample totals 177 males and includes both Bosnian and Croatian victims of the recent war. Mean stature for Eastern Europeans was obtained from the literature. Results show that formulae based on Trotter and Gleser systematically underestimate stature in the Balkans. Because Eastern Europeans are taller than American Whites it is appropriate to use this as an "informative prior" that can be applied to future cases. This informative prior can be used in predictive formulae, since it is probably similar to the sample from which the Balkan forensic cases were drawn. Based on Bayes' Theorem new predictive stature formulae are presented for Eastern Europeans.

Adult↗
PubMed2002

[Effect of stocking density on growth of juvenile Acipenser schrenckii].

The effect of stocking density on growth of juveniles Acipenser schrenckii was studied, and the results showed that juveniles Acipenser schrenckii reared for 28 days in a flowing water system under different stocking densities of 0.232, 0.665, 1.347, and 2.469 kg.m-2 grew in allometry. There were no significant differences between the final and initial SV under the four treatments. The growth efficiency, DWG, NY, and SGR of juveniles were decreased with the increase of stocking densities. However, the FCR and NY were increased with the increase of stocking densities. There were significant differences between these parameters under the low and high densities treatment after 28 days. Moreover, there was a significant negative linear correlation between stocking density (D) and special growth rate (SGR).

Animals↗
PubMed1975

[Comparative quantitative study on brains of wild and laboratory rats. I. Comparison of volume of total brain and classical brain parts].

The intraspecific allometric relation between brain weight and body weight of wild Norway rats and laboratory rats was gained from sufficient material. The intraspecific allometry exponent a=0.25, being typical for mammals, also came out as a result for Norway and laboratory rats. But laboratory rats have 8.3% less brain substance at a comparable body weight. This decrease in brain size was interpreted as an adaption to the specific conditions of domestication and discussed accordingly. Futhermore the fresh volumes of the fundamental brain parts telencephalon, diencephalon, mesencephalon, cerebellum, medulla oblongata, neocortex, corpus striatum and allocortex were ascertained by means of serial sections of 8 Norway and 8 laboratory rats, and they were compared with each other by their average brain proporationing. Consequently, differently strong reduction intensities in the sizes of these brain parts from 1.6% (medulla oblongata) to 12.5% (neocortex) became evident. The high reduction values of corpus striatum (10.9%) and cerebellum (10.3%) were especially remarkable. They almost reached the same degree as the forebrain (10.6%). The size reduction of the measured brain parts of rats, caused by domestication were compared with the results of other domestic mammals and discussed accordingly.

Animals↗