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PubMed1990

Relative growth of brain in the human fetuses: first gestational trimester.

The relative growth of brain weight was studied in 23 Brazilian human fixed fetuses of known age ranging from 9th to 12th weeks post-conception using the allometric method: Y = aXb. The brain weight (grams) was correlated to the fetal parameters of growth: gestational age (weeks post-conception), cephalic perimeter (millimeters) and fetal weight (grams). The brain weight growth presented negative allometry relative to fetal age (b = 0.87) and cephalic perimeter (b = 2.46) and positive allometry relative to gestational age (b = 6.65). These data are important to compare the fetal growth after ultrasonic investigation.

Brain↗
PubMed2006

Statistical approaches to handle proportions as characters.

The handling of morphometric proportions as characters in phylogenetics is methodically hardly elaborated. Common approaches are either to search for statistically significant differences in "index"-values, usually quotients of measures, or to compare regression lines for logarithmic values. The former have their weakness in an insufficient consideration of allometric proportions, the latter in a lack of appropriate methods for testing statistical significance of differences. This contribution presents a methodical approach which considers both allometry and statistical significance. Moreover, not only significance, but also the size of mean differences, as compared to standard deviations, is calculated. If differences are too small, they do not allow to draw a clear distinction between compared groups, and therefore have a low quality as characters. At the beginning of the procedure a test for gradient differences between allometry lines is applied, and if no such are found, a second test for parallel shift between the two lines. If a difference is found, the extent of which exceeds a prearranged limit, it is accepted as a character difference suitable for phylogenetic reconstruction. This method was practically applied by Wiesemüller & Rothe (1999) in a phylogenetic investigation of New World monkeys (Platyrrhini, Primates).

Animals↗
PubMed1990

[Evaluation of skull vault asymmetry using methods of analytical morphometry].

Some vertical frontal C.A.T. sections of 8 skull vaults were studied in evaluating shape asymmetry between left and right curves. Every profile was normalized by subdividing in 120 points and standardized by positioning the sagittal line of skull vault profile parallel to the ordinate axis of a Cartesian system. After these procedures, we tried to detect the asymmetry. In order to achieve these results we used a procedure that we named "Janus", a subset of S.A.M. (Shape Analytical Morphometry) software system, giving an artificial close curve by the mirror composition of left and right cranial vault profiles to match each other. This match was performed by a parabolic fitting for a standard positioning. The procedure was able to split the whole asymmetry information into the isometric and allometric components. We tried to detect allometry in terms of direction and versus with a numerical evaluator of its magnitude; this description was properly a vector. In this pilot study by using 24 sections, we found 20 left and 4 right predominance, expressed time by time by isometry, allometry or both.

Adult↗
PubMed1988

Multivariate analysis of relative growth in the limb bones of Arikara Indians.

The description of relative growth in the limb bones of Arikara Indians from a large archeological sample (N = 412 nonadults) is approached by (1) using a multivariate generalization of the bivariate scaling relationship, and (2) extracting the principal components of log shape. The two methods are shown to be complementary, and advantages accrue to both. Although most of the variability among individuals is related primarily to differences in size, significant age-related differences in shape are disclosed by both approaches. Negative forelimb growth allometry contrasts with positive hind limb allometry and results in decreasing intermembral indices with changing size and age. A within-limb, disto-proximal growth gradient is also evident, inasmuch as the proximal element within each limb grows faster than the distal. A functional link to the human specialization for bipedal locomotion and posture is apparent. A comparison between the ontogenetic results of this study and those from an analysis of static adult scaling from the same populations discloses no similarities between the two and suggests that one type of data cannot be substituted for the other.

Adolescent↗
PubMed1987

Statistical methods for growth allometric studies.

Simple least square regression analysis, major axis regression, and reduced major axis regression have been advocated for straight line fitting to the logarithmically transformed data pairs in bivariate allometric studies. As all these techniques are based on rigid a priori assumptions on the error structure, their application may lead to considerable biases in slope estimation if these requirements are not met. A different mathematical model, the linear functional relationship, allows to remove the bias by estimating the error structure from grouped empirical data. The model is applicable to interspecific and cross-sectional growth allometric studies where natural grouping criteria are available (species, age). The technique is illustrated by growth allometry of myocardial cells and capillaries in the late postnatal period (after weaning) in 33 normal male Wistar rats (group 1: 5 weeks, group 2: 7 weeks, group 3: 13 weeks, group 4: 52 weeks). In left ventricular myocardium fixed by vascular perfusion, length and volume densities of myocardial cells and capillaries were estimated by stereological techniques at the light and electron microscopic level. Total capillary length and total myocardial cell volume were scaled to total myocardial cell length. A comparison of the scaling methods showed an underestimation of the slope and its confidence interval by all regression techniques, which would have led to the erroneous conclusion that the myocardial cell does not remain geometrically similar throughout the normal growth process. Linear functional relationship and the technique of instrumental variables led to nearly identical results and were both compatible with geometric similarity of the myocardial cell during growth. Positive allometry of total capillary length to total myocardial cell length (b = 1.674) demonstrates continuous neoformation of capillaries. The intensity of capillary proliferative activity during growth was intermediate between the reactions observed in myocardial hypertrophy due to pressure overload and that due to physical training. This agrees with the fact that both systemic arterial pressure and cardiac output increase during maturation. The study is designed as a worked example which should enable the practicing researcher to treat data from cross-sectional growth allometric studies with a simple and unbiased statistical method.

Animals↗
PubMed1984

Changes in the nucleic acid and protein content of the Japanese quail during postnatal development.

A study of growth activity in the Japanese quail showed the rate of growth to be the highest, in both sexes, between the ages of 5 and 20 days. Positive allometry was manifested in skeletal muscle development, negative allometry or isometry in the case of the liver and heart. The protein/P DNA ratio rose progressively with age in all the given tissues and attained the maximum prior to sexual maturation. The P RNA/P DNA ratio rose markedly in all the tissues after only a few days and remained high throughout the whole period of development. Growth dynamics in the both sexes followed the same course; the only exception were proteosynthesis indicators, which attained higher values in females, in correlation to their greater body weight.

Animals↗
PubMed1995

Allometric secular change in the long bones from the 1800s to the present.

Allometric secular changes in the six long limb bones for White and Black males from the mid 1800s to the present are examined. Long bone lengths are available from the Terry collection and WWII casualties. We conducted two types of analysis to reveal secular changes. First, allometry scaling coefficients were derived by regressing log bone length onto log stature. These showed that the femur, tibia and fibula were positively allometric with stature, while the humerus, radius and ulna were isometric. The lower limb bones were more positively allometric in the WWII sample than in the Terry sample. Second, secular changes in length of femur and tibia and in the tibia/femur ratio were evaluated, using modern forensic cases in addition to the Terry and WWII samples. This analysis shows that secular increase in lower limb bone length is accompanied by relatively longer tibiae. Secular changes in proportion may render stature formulae based on nineteenth century samples, such as the Terry collection, inappropriate for modern forensic cases. The positive allometry of the lower limb bones argues against using simple femur/stature ratio, which assumes constant proportionality, as an alternative to regression equations.

Black People↗
PubMed1994

Some principles in the dental crown construction in permanent maxillary centrals of Slovenians.

To increase the understanding of the incisors crown form, the lingual fossa depth, crown width and crown thickness between lingual marginal ridges of the permanent maxillary centrals were measured on 257 stone casts of Slovene children. The right-left, male-female differences, as well as the correlations between the variables themselves were analysed. Male centrals exhibited wider and thicker crown compared to female centrals, while the lingual fossa depth showed no sex differences. A positive correlation in terms of positive allometry between lingual fossa depth and crown width was established. A negative lingual fossa depth-crown thickness correlation was found with female left centrals. High right-left symmetry was established, except for the directional asymmetry of all three measured variables on female centrals. The results indicate that the positive correlation in terms of positive allometry between the thickness of the lingual marginal ridges and the crown width is one of the basic principles of the crown formation for the permanent maxillary centrals. Usually we have to work with absolute thickening of the lingual marginal ridges because relative thickening on the account of the crown thickness is less usual. The latter possibility is less favourable for the firmness of the dental crown.

Analysis of Variance↗
PubMed1994

[Relative growth of the pancreas in the human fetus].

The relative growth of the pancreas was studied in 30 human fresh fetuses of known age (ranging from 2nd to 3rd trimesters) by using of the allometric method (Y = a X b). The weight of the pancreas (in grams) was correlated to the fetal parameters of maturity: age (in weeks), crown-rump length (in millimeters) and fetus weight (in grams). The growth of the weight of the pancreas presented positive allometry relative to gestational age and C-R length (b = 4.16 and 3.90 respectively), and light positive allometry relative to the weight of the fetuses (b = 1.15). These data are important today because non invasive methods like ultrasonography make possible to investigate the normal prenatal growth of several organs.

Embryonic and Fetal Development↗
PubMed1993

Glomerulosclerosis and body growth are mediated by different portions of bovine growth hormone. Studies in transgenic mice.

BACKGROUND: Mice transgenic for bovine growth hormone (bGH) gene have increased body weight and severe glomerulosclerosis leading to death in uremia. EXPERIMENTAL DESIGN: The aim of this study was to determine if body growth and glomerulosclerosis were mediated by different bGH regions. Amino acid substitutions in the bGH alpha-helix III were generated, and lines of transgenic mice that expressed these products were developed. Female transgenic mice carrying the native bGH gene (bGH mice), a mutated bGH gene that encodes a destabilized alpha-helix III (bGH-L121P, E126G; bGH-m11 mice), or a mutated bGH gene that encodes a perfect amphiphilic alpha-helix III (bGH-E117L, G119R, A122D; bGH-m8 mice) were examined at 2-3 months and 6-9 months of age. Body, kidney, and heart weights were measured. Urinary glucose, albumin, creatinine, and serum glucose were measured in all mice. Serum levels of insulin-like growth factor I (IGF-I) were measured in the 2-3 month group. Whole blood hemoglobin A1 was measured in some mice of the 6-9 month group. Kidney sections were examined by light and immunofluorescence microscopy. Glomerular volume was measured and related to body weight by allometry. RESULTS: The bGH-m11 mice developed glomerulosclerosis indistinguishable from that seen in bGH transgenic mice, even though they had normal body size. Glomerular growth exceeded body growth by allometry in both bGH and bGH-m11 strains. bGH-m8 mice had glomeruli of appropriate size and normal histologic appearance; however, they were dwarfs. IGF-I was increased in bGH mice; they also had an increased albumin/creatinine ratio at 6-9 months. None of the mice were hyperglycemic. CONCLUSIONS: These data indicated that development of glomerulosclerosis and body growth promotion were mediated by different regions of the growth hormone molecule. The glomerular response to bGH was unique and consisted of increased size and glomerulosclerosis.

Animals↗
PubMed1977

The growth patterns of three hindlimb muscles in the chicken.

This study was designed to investigate the growth patterns of three hindlimb muscles of the chicken relative to the functional-biomechanical demands of increasing body size. The biceps femoris, a bipennate non-postural muscle, grew relatively faster in terms of wet and dry weight than did the parallel-fibred adductor superficialis or the unipennate adductor profundus, both postural muscles. All three muscles exhibited positive allometry (relative to body weight) in muscle length but only biceps femoris and adductor profundus showed positive allometry in cross sectional area adductor superficialis having isometric growth in this parameter. In biceps femoris and adductor superficialis the lengths of the longest and shortest fasciculi grew at equal rates, whereas in adductor profundus the shortest fasciculi grew faster than the longest. We conclude that muscle weight alone is an insufficient indicator of changing function in growing muscle. Hence, growth studies should include other functionally relevant parameters such as cross sectional area, which is proportional to the force-producing capabilities of the muscle, or fibre (fasciculus) length, which is indicative of the absolute amount of stretching or shortening that is possible and of the contraction velocity.

Age Factors↗
PubMedDate not supplied

Finite element morphometry of the midfacial complex in subjects with Angle's Class III malocclusions.

The purpose of this study was to determine whether the morphology of the midface differed in normal (Class I) and midfacially-retrognathic (Class III) prepubertal subjects, and to localize differences morphometrically. Lateral cephalographs of 133 European-American children between 5-11 years of age were traced and average geometries, scaled to an equivalent size, were generated based upon seven nodes (pterygoid point, PTS; rhinion, RO; posterior nasal spine, PNS; midpalatal point, MPP; anterior nasal spine, ANS; subspinale, A; and prosthion, Pr). The samples also were subdivided into seven age- and sex-matched groups for morphometric comparisons. Procrustes analysis indicated that the overall midfacial configurations differed statistically (P < 0.05). Therefore, a color-coded finite element (FEM) program was used to localize differences in morphology graphically. Comparing Class I and III groups for size-change, FEM revealed that negative allometry was evident in the posterior half of the midfacial configuration localized between PTS, PNS, and MPP. The anterior half was more isotropic, however, but the anterior-most aspect of the configuration between Pr and RO showed some positive allometry particularly in the premaxillary and incisor regions. For shape-change, major differences in shape over the entire midface were not as evident, with an isotropic midfacial morphology for normal and Class III subjects. It is concluded that an identifiable pattern of deformation is evident for the Class III subjects during the prepubertal growth period. Therefore, midfacial retrognathia associated with Class III malocclusions results, at least in part, from deficient anteroposterior elongation of the midfacial complex allied with deformation of the premaxillary region.

Cephalometry↗
PubMed2024

Adaptive or non-adaptive? Cranial evolution in a radiation of miniaturized day geckos.

Lygodactylus geckos represent a well-documented radiation of miniaturized lizards with diverse life-history traits that are widely distributed in Africa, Madagascar, and South America. The group has diversified into numerous species with high levels of morphological similarity. The evolutionary processes underlying such diversification remain enigmatic, because species live in different ecological biomes, ecoregions and microhabitats, while suggesting strikingly high levels of homoplasy. To underscore this evolutionary pattern, here we explore the shape variation of skull elements (i.e., cranium, jaw and inner ear) using 3D geometric morphometrics and phylogenetic comparative methods on computed tomography scans (CT-scan) of a sample encompassing almost all recognized taxa within Lygodactylus. The results of this work show that skull and inner ear shape variation is low (i.e., there is high overlapping on the morphospace) across geographic regions, macrohabitats and lifestyles, implying extensive homoplasy. Furthermore, we also found a strong influence of allometry shaping cranial variation both at intra and interspecific levels, suggesting a major constraint underlying skull architecture, probably as a consequence of its miniaturization. The remaining variation that is not allometric is independent of phylogeny and ecological adaptation and can probably be interpreted as the result of intrinsic developmental plasticity. This, in turn, supports the interpretation that speciation in this group is largely concordant with a non-adaptive hypothesis, which results mainly from vicariant processes.

Animals↗
PubMed1998

Heterochronic processes in human evolution: an ontogenetic analysis of the hominid pelvis.

Changes in pelvic shape in human ontogeny and hominid phylogeny suggest that the heterochronic processes involved differ greatly from the neotenic process traditionally described in the evolution of the skull. The morphology of 150 juvenile and adult pelves of African apes, 60 juvenile and adult pelves of modern humans, two adult pelves and a juvenile hip bone of australopithecines (Sts 14, AL 288, MLD 7) was studied. Multivariate results, ontogenetic allometries, and growth curves confirm that the pelvic growth pattern in humans differs markedly from those of the African apes. The results permit the following conclusions. First, the appearance of a new feature (acetabulo-cristal buttress and cristal tubercle) at the time of human birth allows the addition of traits, such as the attainment of a proportionally narrower pelvis, with more sagittally positioned iliac blades. Pelvic proportions and orientation change progressively in early childhood as bipedalism is practiced. Other changes in pelvic proportions occur later with the adolescent growth spurt. Second, comparison of juvenile and adult australopithecines to modern humans indicates that 1) some pelvic traits of adult Australopithecus resemble those of neonate Homo; 2) the pelvic growth of Australopithecus was probably closer to that of apes, than to that of humans; and 3) prolonged growth in length of hindlimb and pelvis after sexual maturity seems to be a unique feature of Homo. The position of the acetabulo-cristal buttress and of the cristal tubercle on the ilium are similar in adult Australopithecus and neonate Homo suggesting that this feature may have been displaced later during hominid evolution. Progressive displacement of the acetabulo-cristal buttress on the ilium occurs both during hominid evolution (from Australopithecus to Homo sapiens) and human growth (from neonate to adult). This suggests peramorphic evolution of the pelvic morphology of hominids combining three processes of recapitulation (pre-displacement, acceleration and time hypermorphosis). The results lend credence to the hypothesis that no single heterochronic process accounts for all human evolutionary change; rather this reflects a combination of relative changes in growth rhythm and duration, including other perturbations, such as the appearance of new morphological features.

Adolescent↗
PubMed1999

The recognition and evaluation of homoplasy in primate and human evolution.

Homoplasy has been a prominent issue in primate systematics and phylogeny for as long as people have been studying human evolution. In the past, homoplasy, in the form of parallel evolution, was often considered the dominant theme in primate evolution. Today, it receives blame for difficulties in phylogenetic analysis, but is essential in the study of adaptation. This paper reviews the history of study of homoplasy, methods of defining homoplasy, and methodological and biological factors that generate homoplasy. A post hoc definition of homology and homoplasy, based on patterns of character distributions and their congruence or incongruence on a cladogram, is the most consistent method of recognizing these phenomena. Defined this way, homology and homoplasy are mutually exclusive. However, when different levels of analysis are examined, it is seen that homoplasy at one level, such as adult phenotype, often exists simultaneously with homology at a different level, such as developmental process. Thus, in some cases, patterns of homoplasy may point to underlying similarities that reflect the shared heritage of a particular clade. This is an old concept that is being renewed on the strength of recent trends in developmental biology. Factors that influence homoplasy include character definition and a host of biological factors, such as developmental constraints, allometry, and adaptation. These interact with one another to provide explanations of homoplastic patterns. Because of the repetition of events, explanations of homoplastic features are often more reliable than those for homologous features, and serve as effective tests for hypotheses of evolutionary process. In some cases, particular explanations of homoplasy lead to generalizations about the likelihood of homoplasy in a type of structure. The structure may be adaptive or highly epigenetic, or it may belong to an anatomical system considered to be more prone to homoplasy than others. However, our review shows that these generalizations are usually based on theory, and contradictory expectations can be developed under different theoretical models. More rigorous empirical studies are necessary to discover what, if any, generalizations can be made about the likelihood of homoplasy in different types of characters.

Adaptation, Physiological↗
PubMed1999

Secular change in long bone length and proportion in the United States, 1800-1970.

We examine secular change in long bone lengths and allometry of Americans dating from the mid-19th century to the 1970s. Skeletal samples were derived from the Huntington Collection, Terry Collection, World War II casualties, and the Forensic Anthropology Data Bank. Regression of bone length on year of birth allowed evaluation of the secular change in bone length. Size was computed as the geometric mean of all bone lengths, and shape as the ratio of each bone to size. These variables were then regressed on year of birth, allowing evaluation of allometric secular change. The results revealed a pattern of change that can be summarized as follows: male secular change is stronger than female, lower limb bone secular change is more pronounced than upper limb bone change, and distal bones change more than proximal bones, particularly in the lower limb. In males, white changes are uniformly higher than black but these differences do not rise to the level of statistical significance. Environmental forces, such as nutrition and disease, are the usual causes of secular changes in overall size. This paper shows that long bone proportions also respond to these same environmental factors. Moreover, the changes in body proportion are likely to be due to allometric consequences of growth changes that occur early in life. Am J Phys Anthropol 110:57-67, 1999.

Anthropometry↗
PubMed1999

Evolving ideals of male body image as seen through action toys.

OBJECTIVE: We hypothesized that the physiques of male action toys--small plastic figures used by children in play--would provide some index of evolving American cultural ideals of male body image. METHOD: We obtained examples of the most popular American action toys manufactured over the last 30 years. We then measured the waist, chest, and bicep circumference of each figure and scaled these measurements using classical allometry to the height of an actual man (1.78 m). RESULTS: We found that the figures have grown much more muscular over time, with many contemporary figures far exceeding the muscularity of even the largest human bodybuilders. DISCUSSION: Our observations appear to represent a "male analog" of earlier studies examining female dolls, such as Barbie. Together, these studies of children's toys suggest that cultural expectations may contribute to body image disorders in both sexes.

Adult↗
PubMed1999

Pharmacokinetics of halofantrine in the rat: stereoselectivity and interspecies comparisons.

The antimalarial drug, halofantrine, is chiral and is administered clinically as the racemate. In order to define the pharmacokinetic properties of halofantrine enantiomers in the rat, male Sprague-Dawley rats (264-311 g) were given halofantrine HCl orally (n = 5; 14 mg/kg) or intravenously (i.v.) (n = 5; 2 mg/kg). Plasma samples were collected over a 72 h period, and these were assayed for halofantrine enantiomer concentrations using a stereospecific reverse phase HPLC assay. After dosing by both routes of administration the (+) enantiomer was found to have significantly higher AUC, and higher Cmax after oral dosing. Pharmacokinetic analysis indicated that in the rat, the (+) enantiomer is cleared slower, and is less extensively distributed than its antipode. The bioavailability of the enantiomers after oral administration was less than 27%. Urinary excretion was a negligible route of elimination of unchanged drug. Using allometry, the pharmacokinetics of (+/-)-halofantrine in rats scaled nicely with literature data from dogs and humans. The pharmacokinetic properties of halofantrine enantiomers in the rat resembled those seen in humans, indicating that the rat is a good model for the study of halofantrine pharmacokinetics.

Administration, Oral↗