First rib metamorphosis: its possible utility for human age-at-death estimation.

Human first ribs demonstrate predictable, sequential changes in shape, size, and texture with increasing age, and thus, can be used as an indicator of age at death. Metamorphosis of the first rib's head, tubercle, and costal face was documented in a cross-sectional sample of preadult and adult first ribs of known age at death from the Hamann-Todd skeletal collection (Cleveland Museum of Natural History, Cleveland, Ohio). Blind tests of the usefulness of the first rib as an age indicator were conducted, including tabulation of intraobserver and interobserver inaccuracies and biases. First rib age estimates show inaccuracies and biases by decade comparable to those generated by other aging techniques. Indeed, the first rib method is useful as an isolated age indicator. When used in conjunction with other age indicators, the first rib improves the quality of summary age assessments.     

Is the first rib a reliable indicator of age at death assessment? Test of the method developed by Kunos et al (1999)

The aim of this study was to test the method Kunos and his colleagues (1999) developed on the first rib to assess adult age-at-death. The method was applied on a sample of known age and sex, selected from a Thai collection. The procedure being subjective, we chose to estimate an age category rather than a precise age.

The results show that only 55% of the individuals are correctly classified and that the number of subjects over 60 years old is under-estimated. Three explanations are given: the modifications of the first rib related with ageing are more variable than previously stated, the technique is too subjective and difficult to apply and the morphological changes of the first rib are different between North-American and Thai people.     

Semiparametric method for estimating paleodemographic profiles from age indicator data.

This paper addresses the problem of estimating an age-at-death distribution or paleodemographic profile from osteological data. It is demonstrated that the classical two-stage procedure whereby one first constructs estimates of age-at-death of individual skeletons and then uses these age estimates to obtain a paleodemographic profile is not a correct approach. This is a consequence of Bayes' theorem. Instead, we demonstrate a valid approach that proceeds from the opposite starting point: given skeletal age-at-death, one first estimates the probability of assigning the skeleton into a specific osteological age-indicator stage. We show that this leads to a statistically valid method for obtaining a paleodemographic profile, and moreover, that valid individual age estimation itself requires a demographic profile and therefore is done subsequent to its construction. Individual age estimation thus becomes the last rather than the first step in the estimation procedure. A central concept of our statistical approach is that of a weight function. A weight function is associated with each osteological age-indicator stage or category, and provides the probability that a specific age indicator stage is observed, given age-at-death of the individual. We recommend that weight functions be estimated nonparametrically from a reference data set. In their entirety, the weight functions characterize the relevant stochastic properties of a chosen age indicator. For actual estimation of the paleodemographic profile, a parametric age distribution in the target sample is assumed. The maximum likelihood method is used to identify the unknown parameters of this distribution. As some components are estimated nonparametrically, one then has a semiparametric model. We show how to obtain valid estimates of individual age-at-death, confidence regions, and goodness-of-fit tests. The methods are illustrated with both real and simulated data.     

Multifactorial determination of skeletal age at death: a method and blind tests of its accuracy

Traditional methods of estimating skeletal age at death have relied solely on the pubic symphyseal face or on this indicator combined with others in nonsystematic ways. A multifactorial method is presented that uses a principal components weighting of five indicators (public symphyseal face, auricular surface, radiographs of proximal femur, dental wear, and suture closure). This method has been tested by completely blind assessment of age in two samples from the Todd collection carefully screened for accuracy of stated age at death. Results show a marked superiority of the multifactorial method over any single indicator with respect to both bias and accuracy. This represents the first truly blind test of an age-at-death indicator or system, as the test populations were independent of the system(s) being tested, and the age, sex, and ethnogeographic origin of the individuals being assessed (as well as the compositions of the test samples with respect to these variables) were completely unknown until the tests were completed. Implications for paleodemography are discussed.     

中国近海的两种宽吻海豚

本文研究了采自黄海和东海的23件宽吻海豚标本及采自南海的10件南宽吻海豚标本。宽吻海豚体腹面灰白色,成体最小的全长大于2.5米,颅基长495-580毫米。南宽吻海豚体腹面具纵长形暗色点斑,成体最大的全长小于2.5米,颅基长455-497毫米。两者的颅骨和颅后骨胳各有一些差别。中国南海标本的形态性状与南非海域及巴基斯坦沿岸的宽吻海豚相似。黄海和东海标本与东太平洋的标本有一些差别,而与南非及不列颠海域的宽吻海豚标本相似。     

The effect of calcification on the structural mechanics of the costal cartilage

The costal cartilage often undergoes progressive calcification with age. This study sought to investigate the effects of calcification on the structural mechanics of whole costal cartilage segments. Models were developed for five costal cartilage specimens, including representations of the cartilage, the perichondrium, calcification, and segments of the rib and sternum. The material properties of the cartilage were determined through indentation testing; the properties of the perichondrium were determined through optimisation against structural experiments. The calcified regions were then expanded or shrunk to develop five different sensitivity analysis models for each. Increasing the relative volume of calcification from 0% to 24% of the cartilage volume increased the stiffness of the costal cartilage segments by a factor of 2.3–3.8. These results suggest that calcification may have a substantial effect on the stiffness of the costal cartilage which should be considered when modelling the chest, especially if age is a factor.     

Relationships between abdominal and diaphragmatic volume displacements

We investigated the relationship between the volumes displaced by the diaphragm and the abdominal wall during spontaneous breathing in supine anesthetized dogs. Diaphragmatic volume displacement (Vdi) was calculated from measurements taken from anteroposterior fluoroscopic images employing a previously described geometric model. The volume displacement of the abdominal wall (Vabd) was measured with a calibrated Respitrace. Shortening of single diaphragm muscle bundles in costal and crural regions was measured as the distance between radiopaque beads sutured to the peritoneal surface of the muscle. We found that Vdi always exceeded Vabd, but Vabd/Vdi was larger in animals in which the abdominal wall was more compliant. In this preparation, Vdi is better correlated with costal than with crural shortening. Vabd did not correlate with either costal or crural shortening. We infer that the difference between Vdi and Vabd reflects the volume displacement of the lower rib cage caused by diaphragm contraction. This volume difference was tightly correlated with costal shortening. We conclude from these data that coupling between Vdi and Vabd is influenced by the relative compliances of the chest wall and abdomen. Shortening of regions of the diaphragm may have variable relationships to the measured volume displacement, but costal shortening is intimately related to expansion of the lower rib cage.     

Regional metabolic differences in the rat diaphragm

This study characterized the biochemical properties of the rat diaphragm by measuring the activities of selected citric acid cycle and glycolytic enzymes. The diaphragm was removed from 10 female Sprague-Dawley rats (180 days old) and dissected into five discrete anatomic regions: crural (region 1), left posterior costal (region 2), left anterior costal (region 3), right anterior costal (region 4), and right posterior costal (region 5). Sections were assayed for total protein concentration and the activities of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH). The SDH activity in the crural region was approximately 18% lower (P less than 0.05) than that in any costal region. Furthermore, protein concentration was significantly lower (P less than 0.05) in the crural region compared with all costal regions. In contrast, costal regions 2-5 did not significantly differ from each other in protein concentration or SDH activity. LDH activity did not differ significantly (P greater than 0.05) between regions. Finally, the LDH-to-SDH activity ratio was significantly higher (P less than 0.05) in the crural diaphragm compared with all costal regions. We conclude that the crural region of the rat diaphragm is significantly lower in oxidative capacity than all the costal regions. Investigators who use a rodent model to study diaphragmatic function and plasticity should consider the oxidative heterogeneity of the diaphragm when designing experiments.     

Costal cartilages--a clue for determination of sex

Mineralization and ossification in the human costal cartilages were studied radiologically. The aim of our study was to evaluate differences between males and females with respect to patterns of costal cartilage calcification and also with respect to ageing. Material for this study consists of 1044 chest and abdominal radiograms of the Czech population from the Department of Radiology (537 males and 507 females). Further radiograms of 18 chest plates were obtained at routine necropsy of cadavers. The radiograms were examined for pattern of ossification of the costal cartilage. The first rib cartilages were not considered because there are no sex differences. The lower ribs exhibit sexual dimorphism. Mineralization and ossification changes appear at the end of puberty and their occurrence increases with age. The sexual difference in pattern of human costal cartilages is statistically significant and thus highly predictive of sex determination.     

Shape and orientation of articular facets of cervical vertebrae (C3-C7) in dogs denoting axial rotational ability: an osteological study

Macerated cervical vertebrae of 139 adult and 39 juvenile dogs were assessed for morphological evidence of axial rotation, which is denoted by the shape and orientation of the articular facets. The potential effect of the presence of caudal costal foveae at C7 on facet geometry was also investigated. Four variations of caudal facet shape were evident, namely, plane, concave, convex and sigmoid. The earliest onset of change in shape from plane to curved was noticed in juvenile dogs who were older than 8 weeks. The incidence of curved facets denoting axial rotation ability was observed to increase on descending down the cervical spine. Concave caudal facets were more frequently present in males and in large dogs (P < 0.001), compared to Dachshunds and small breeds. The degree of concavity was not related to age but was associated with the transverse distance between the most medial aspects of the caudal and corresponding cranial facets (P < 0.05). In large breeds, the presence of concave caudal facets at C7 was inversely related to the presence of caudal costal foveae (P < 0.01). The effect of axial rotation is discussed in context with clinical literature suggesting that axial rotation might attribute to the development of the wobbler syndrome.     

A cadaveric analysis of the ideal costal cartilage graft for Asian rhinoplasty

Augmentation rhinoplasty of the Asian nose may be effectively accomplished with alloplastic materials. However, certain circumstances mandate the use of autologous grafts (e.g., dorsal augmentation that exceeds 8 mm and patient intolerance of alloplastic implants). Septal and auricular cartilages are inadequate for dorsal augmentation of the Asian nose. The use of costal cartilage for autologous augmentation in select Asian patients has proven to be a reliable method in more than 500 operative cases during a 10-year period. This study was designed to evaluate the ideal costal cartilage graft for augmentation rhinoplasty. Forty-two preserved cadavers were studied for the relationship of the individual rib cartilages to the surrounding tissue and for the length and caliber of each costal cartilage. The seventh rib was found to be the ideal rib graft by virtue of its safe location and overall size for grafting. The seventh rib is situated over the abdominal cavity, so the risk of pneumothorax is insignificant. The internal thoracic artery and vein descend in close apposition behind the first to sixth ribs but begin a course medial to the ribs inferior to this point, and therefore vascular injury during seventh-rib harvesting is unknown. The seventh rib also provides the greatest overall available length (90.7 mm, right; 89.6 mm, left) and thickness (17.6 mm, right; 17.5 mm, left). Despite the more conspicuous location of the incision required to harvest the seventh rib, the limited 3-cm incision that is used has healed favorably in almost all cases. The other major drawback for seventh-rib harvesting is the dissection required through the overlying rectus abdominis muscle, but little technical difficulty or postoperative morbidity is added with muscle dissection. The seventh rib is advocated as the ideal choice for augmentation rhinoplasty and potentially other recipient sites.     

Characterization of a chondrocyte primary culture from rib cartilage of the rat

In order to standardize and to characterize a chondrocyte primary culture, cells from rat rib resting cartilage were used. High yield (0.99 +/- 0.18 x 10(6) cells/rat) and viability (91.76%) of costal cartilage cells was reached by enzymatic digestion with collagenase. The cells were cultivated in Dulbecco's medium (DME) supplemented with 10%. Heat inactivated newborn calf serum, at 37 degrees under humidified atmosphere of 5% CO2 in air. Two or three days after plating, the cells were attached to the surface of tissue culture weel, and began dividing. Adhesion was independent of plating density. The doubling time of cell population was found to be 23.19 hours. The cells became a monolayer and required easy maintenance. The results support the contention that rat costal cartilage is a good source of chondrocytes for primary culture cells experiments.     

Effect of obesity on the reliability of age-at-death indicators of the pelvis

During medicolegal investigations, forensic anthropologists commonly use morphological changes in the auricular surface of the ilium and the symphyseal face of the pubis to estimate age. However, obesity may impact the reliability of age estimations based on pelvic joints. Over the past several decades, the prevalence of obesity has dramatically increased in the United States (US). Since the rate of progression through age-related stages of weight-bearing joints may be influenced by excessive body mass, it is important that anthropologists understand how obesity affects age-related morphological changes in the skeleton. This study investigates the effects of obesity on the validity of the estimated age-at-death based on the Buckberry–Chamberlin and Suchey–Brooks methods by comparing US adults considered normal BMI (BMI 18.5–24.9) and obese (BMI ≥ 30). The obese group exhibits overall greater bias (overestimation of age) and inaccuracy, less precision, and lower correlations between estimated and known age than the normal BMI group using both methods, although differences in the pubic symphysis are not statistically significant. For the auricular surface the age of transition from one phase to the next is lower and the standard deviations are greater for the obese as compared to normal weight individuals. This study helps to elucidate how obesity affects the rate of age-related skeletal change of the human pelvis, and shows that the pubic symphysis may be a more reliable indicator of age in obese individuals and that greater standard deviations are needed for obese individuals when estimating age-at-death from the pelvis. Am J Phys Anthropol 156:595–605, 2015. © 2014 Wiley Periodicals, Inc.     

Analysis of quantitative methods for rib seriation using the Spitalfields documented skeletal collection

Accurate rib seriation is essential in forensic anthropology and bioarchaeology for determination of minimum numbers of individuals, sequencing trauma patterns to the chest, and identification of central ribs for use in age estimation. We investigate quantitative methods for rib seriation based on three metric variables: superior (anterior) costo-transverse crest height (SCTCH), articular facet of the tubercle-to-angle length (AFTAL), and head-to-articular facet length (HAFL). The sample consists of complete but unseriated sets of ribs from 133 individuals from the documented (known age and sex) and undocumented skeletal collections of Christ Church Spitalfields, London. This research confirms the results of an earlier study (Hoppa and Saunders [1998] J. Forensic. Sci. 43:174-177) and extends it with the application of two new metric traits and further analyses of sex differences. Analyses of variance showed that SCTCH and AFTAL are significantly associated (P < 0.001) with rib number. Tukey tests of pairwise rib comparisons revealed that for two dimensions (SCTCH and AFTAL), the central ribs (3rd-6th) are significantly distinct from each other (P < 0.05). Using simple ranking of either the SCTCH or AFTAL traits, the proportion of correctly identified ribs within +/-1 position was 80%, compared to initial seriation using morphological methods (Dudar [1993] J. Forensic. Sci. 28:788-797; Mann [1993] J. Forensic. Sci. 28:151-155). Significant sex dimorphism was also identified for these two traits. Analysis of the HAFL trait produced somewhat equivocal results, suggesting that this variable is not reliable for rib seriation. The variable SCTCH proves to be the most useful dimension for seriation, and shows that all but the 7th-9th ribs can be distinguished from others in the sequence, with important results for the 4th rib, where ranking allowed identification in 86% of cases, consistent with morphological methods for intact ribs.     

Regional deformation of the canine diaphragm.

To follow regional deformation of the diaphragm in dogs, radiopaque markers were implanted under surgical anesthesia into different anatomic regions of the muscle in triangular arrays (approximately 1 cm to a side). After recovery from surgery, changes in area and shape of the triangles were followed with biplane cinefluorography during quiet breathing and during inspiratory efforts against an occluded airway (Mueller maneuvers). From changes in shape of the triangles during contraction, area changes were decomposed into a major direction and magnitude of shortening (Eg1) and a minor length change (Eg2) perpendicular to Eg1, both expressed as a fraction of initial length at end expiration. With the use of these techniques, systematic differences in regional area change were observed in different parts of the diaphragm during inspiratory efforts at different lung volumes. Regional area always decreased during contraction in the crural and midcostal zones of apposition to the rib cage. Area decreased less and often increased during inspiratory efforts in the costal dome near the central tendon and in the costal region near its rib cage insertion. Differences in regional area change were not due to differences in the Eg1 in different parts of the diaphragm but were a consequence of differences in widening of the muscle along Eg2 perpendicular to the direction of Eg1. As lung volume was passively increased above functional residual capacity, regional area decreased in all parts of the diaphragm except in the costal regions near rib cage insertion, where area increased.     

Mechanical coupling of upper and lower canine rib cages and its functional significance

We studied rib cage distortability and reexamined the mechanical action of the diaphragm and the rib cage muscles in six supine anesthetized dogs by measuring changes in upper rib cage cross-sectional area (Aurc) and changes in lower rib cage cross-sectional area (Alrc) and the respective pressures acting on them. During quiet breathing in the intact animal the rib cage behaved as a unit (Aurc: 14.6 +/- 7.9 vs. Alrc: 15.1 +/- 9.6%), whereas considerable distortions of the rib cage occurred during breathing after bilateral phrenicotomy (Aurc: 21.0 +/- 5.1 vs. Alrc: 7.0 +/- 4.8%). These distortions were even more pronounced during phrenic nerve stimulation and separate stimulation of the costal and crural parts of the diaphragm (e.g., phrenic nerve stimulation; Aurc: -7.1 +/- 5.1 vs. Alrc: 6.9 +/- 3.5%). During the latter maneuvers the upper rib cage deflated along the relationship between upper rib cage dimensions and pleural pressure obtained during passive deflation, whereas the lower rib cage inflated close to the relationship between lower rib cage dimensions and abdominal pressure obtained during passive inflation. The latter relationship is expected to differ between costal and crural stimulation, since costal action has both an appositional and insertional component and crural action only has an appositional component. The difference between costal and crural stimulation, however, was relatively small, and the slopes were only slightly steeper for the costal than for the crural stimulation (2.9 +/- 1.2 vs. 2.2 +/- 1.0%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Elastostatic analysis of the human thoracic skeleton

An elastostatic, finite element model (designated THORAX I) of the human thoracic skeleton has been developed. The model includes the primary load-carrying members of the thorax; namely, the sternum, costal cartilage, ribs, and vertebral column. The soft tissue has been neglected.

Using gross geometric data measured from a skeleton with an apparent ‘small’ frame and approximate cross-sectional properties, the THORAX I model has been subjected to three loading distribution applied to the anterior chest wall in the anterior-posterior direction. Calculations were carried out on the IBM 7094 computer, and primary attention was focused upon the displacement fields of the sternum, costal cartilage and ribs and stresses in costal cartilage and ribs. The sternum and rib nodal point displacement fields are reported in detail, and a simple 2-degree-of-freedom model for the sternum, which correlates well with the analytic results, is also presented. Maximum normal stresses in the cartilage and bony regions of the individual ribs for one loading condition are also given.     

Estimating the distribution of probable age-at-death from dental remains of immature human fossils

In two historic longitudinal growth studies, Moorrees et al. (Am J Phys Anthropol 21 (1963) 99-108; J Dent Res 42 (1963) 1490-1502) presented the "mean attainment age" for stages of tooth development for 10 permanent tooth types and three deciduous tooth types. These findings were presented graphically to assess the rate of tooth formation in living children and to age immature skeletal remains. Despite being widely cited, these graphical data are difficult to implement because there are no accompanying numerical values for the parameters underlying the growth data. This analysis generates numerical parameters from the data reported by Moorrees et al. by digitizing 358 points from these tooth formation graphs using DataThief III, version 1.5. Following the original methods, the digitized points for each age transition were conception-corrected and converted to the logarithmic scale to determine a median attainment age for each dental formation stage. These values are subsequently used to estimate age-at-death distributions for immature individuals using a single tooth or multiple teeth, including estimates for 41 immature early modern humans and 25 immature Neandertals. Within-tooth variance is calculated for each age estimate based on a single tooth, and a between-tooth component of variance is calculated for age estimates based on two or more teeth to account for the increase in precision that comes from using additional teeth. Finally, we calculate the relative probability of observing a particular dental formation sequence given known-age reference information and demonstrate its value in estimating age for immature fossil specimens.     

Larval structures associated with larva-to-adult trophallaxis in Platythyrea (Hymenoptera : Formicidae)

Larvae of Platythyrea arnoldi, P. modesta, P. schultzei and P. sp. (Hymenoptera : Formicidae) were found to have a well-developed, distinctive median tubercle on their 7th abdominal sternites. The first 2 species also had a tubercle on the 8th abdominal sternite. Specialised epithelial cells surround a deep invagination that opens through an orifice to the base of the tubercle on the 7th abdominal sternite of at least 3 of the species. P. lamellosa has a poorly developed tubercle. A secretion was seen at the base of the tubercle of a P. arnoldi larva, and adult ants of this species and of P. sp. and P. schultzei were often seen licking the posterior face of the tubercles for extended periods. They were feeding on a secretion originating from the orifice beneath the tubercle.