Age‐Related Difference in Postural Control During Recovery from Posterior and Anterior Perturbations

Decreased reactive postural responses in elderly adults may place them at increased risk for falls and related injuries. The first step in addressing the high rate of falls in the elderly population is to determine a baseline for postural response in healthy young and healthy elderly individuals. To determine these age‐related differences in reactive postural responses during recovery from posterior and anterior perturbations, we used the tether‐release method in conjunction with a motion analysis system to evaluate overall movement latencies, overall movement amplitude and velocity, and joint‐specific amplitude and velocity in healthy young (n = 10, mean age=25 ± 5) and healthy elderly participants (n = 10, mean age = 67 ± 6). During posterior perturbations, healthy elderly participants had increased recovery time (P = 0.01) and ratio of center of mass to step length (P = 0.013) when compared with young participants. Elderly participants also had decreased step length (P = 0.006), peak COM velocity (P = 0.01), peak knee flexion angle (P = 0.002), and decreased hip (P = 0.005) and knee (P = 0.0005) average angular velocity when compared with young participants. We conclude that these movement deficiencies at the hip and knee limited the length of the recovery step. With this restricted step, elderly participants could not achieve adequate mechanical advantage to counteract the displacement of their COM using a single step. During anterior perturbations, elderly participants did not exhibit any significant differences compared to young participants in overall movement variables. This understanding of postural responses in healthy individuals is clinically relevant to the development of rehabilitation programs for individuals at high fall risk. Anat Rec, 298:346–353, 2015. © 2014 Wiley Periodicals, Inc.     

Age‐Related Changes of the Oligodendrocytes in Rat Subcortical White Matter

The age‐related changes, of the oligodendrocytes in rat subcortical white matter, were investigated in this study. The oligodendrocytes in subcortical white matter were labeled with anti‐2′,3′‐cyclic nucleotide 3′‐phosphodiesterase antibody (anti‐CNPase antibody, a specific marker of oligodendrocytes). The total number of CNPase⁺ cells was estimated with an unbiased stereological technique, the optical fractionator. In this study, we found that the total number of CNPase⁺ cells in the young male rats and aged male rats was 14.4 ± 1.2 × 10⁶ and 9.0 ± 1.0 × 10⁶, respectively. The total number of the CNPase⁺ cells in the subcortical white matter of aged rats was significantly decreased by 37.5% when compared to young male rats. This study demonstrated that there was an aged‐related decrease of the oligodendrocytes in subcortical white matter. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Comparison of Dentoalveolar Morphology in WT and P2X7R KO Mice for the Development of Biomechanical Orthodontic Models

It has been suggested that the absence of the P2X7 receptor affects long bone morphology, and that one of the cytokines dependent on its activation may also affect tooth morphology. P2X7R KO (knockout) were compared with C57B/6 WT mice (background strain) to identify differences in a maxillary molar and surrounding bone. Nineteen WT and 12 KO mouse maxillae were scanned and 3D‐reconstructed using microCT. Tooth dimensions were measured and 3D bone morphometry was conducted. A finite element model was constructed based on the results. No statistically significant differences were found in dentoalveolar characteristics between the two mouse types. A single finite element model of the tooth can be used to mechanically represent both strains. P2X7R does not have a major effect on alveolar bone or tooth morphology. The P2X7R effects are site‐specific. Anat Rec, 2009. © 2008 Wiley‐Liss, Inc.     

Stereological Investigation of Age‐Related Changes of the Capillaries in White Matter

We, for the first time, investigated the age‐related changes of the capillaries in white matter using immunohistochemistry and stereological techniques. Ten young female (7 months) and 10 aged female (27 months) rats were used. The total length, total volume, and total surface area of the capillaries in white matter of aged rats were all significantly lower than those of young rats. The age‐related changes of the capillaries in white matter may have important implications for age‐related white matter atrophy and age‐related cognitive impairments. Anat Rec 293:1400–1407, 2010. © 2010 Wiley‐Liss, Inc.     

Age‐Related Changes in Bone‐Strength‐Associated Geometry Indices in Naive Human Population

The aim of the present study was to evaluate age‐ and sex‐related changes in the geometry parameters (metacarpal cortical index (MCI) and Breaking Bending Resistance Index [BBRI]) of long hand bones in a large Chuvashian cohort using cross‐sectional and longitudinal study designs. The data were gathered in 1994 (557 individuals) and 2002 (513 individuals). The latter sample included 260 individuals who were studied only during the second expedition, and 253 individuals who were previously investigated in 1994. Statistical analyses included a maximum likelihood‐based model‐fitting technique and a t‐test comparison. Our study describes age‐related MCI and BBRI changes in both sexes from the age of 18 years to 84 years. At any age, the BBRI values were higher in males than in females, but MCI was greater in females than in males before age 50 and lower after that age. The study provides initial evidence of a secular trend in MCI and BBRI. In male hand bones, the cortex became relatively thicker and it better resisted bending and breaking in comparison to individuals born at the beginning of the 20th century. In females, the trend toward higher MCI values can be observed only in those born between 1936 and 1966 and the trend toward higher BBRI values stopped in 1950. Anat Rec, 291:835‐844, 2008. © 2008 Wiley‐Liss, Inc.     

站、坐位态骨盆应力分布的实验研究

目的：明确骨盆的应力分布，指导骨盆肿瘤瘤段骨切除后骨盆环的重建及人工半骨盆的设计与固定。方法：实验取完整骨盆的新鲜尸体（意外死亡）4具，采用应变计测量方法，对不同状态下骨盆的应力进行分析。结果：站立时，骶髂关节中部、耻骨支、髋关节前上方承受较大的压应变；而坐位时，坐骨支、骶髂关节中下部、耻骨支均承受较大的压应变。结论：站立时应力主要是经髋臼的前上方耻骨、骶髂关节传导，人工半骨盆置换设计与置换时，其结构应予加强，并作到确切固定，尤其是骶髂关节的中下部。     

Postnatal Mandibular Cheek Tooth Development in the Miniature Pig Based on Two‐Dimensional and Three‐Dimensional X‐Ray Analyses

The miniature pig is a useful large laboratory animal model. Various tissues and organs of miniature pigs are similar to those of humans in terms of developmental, anatomical, immunological, and physiological characteristics. The oral and maxillofacial region of miniature pigs is often used in preclinical studies of regenerative dentistry. However, there is limited information on the dentition and tooth structure of miniature pigs. The purpose of this study was to examine the time‐course changes of dentition and tooth structure (especially the root) of the miniature pig mandibular cheek teeth through X‐ray analyses using soft X‐ray for two‐dimensional observations and micro‐CT for three‐dimensional observations. The mandibles of male Clawn strain miniature pigs (2 weeks and 3, 5, 7, 9, 11, 14, 17, and 29 months of age) were used. X‐ray analysis of the dentition of miniature pig cheek teeth showed that the eruption pattern of the miniature pig is diphyodont and that the replacement pattern is vertical. Previous definitions of deciduous and permanent teeth often varied and there has been no consensus on the number of teeth (dentition); however, we found that three molars are present in the deciduous dentition and that four premolars and three molars are present in the permanent dentition. Furthermore, we confirmed the number of tooth roots and root canals. We believe that these findings will be highly useful in future studies using miniature pig teeth. Anat Rec, 2013. © 2013 Wiley Periodicals, Inc.     

Stereological Investigation of the Age‐Related Changes of the Myelinated Fibers in the Hippocampus of Male Rats

The decline of hippocampus‐dependent learning and memory during normal aging is not associated with neuron death and synapse loss. Until now, age‐related changes in the myelinated fibers of the hippocampus have not been investigated. Therefore, in this study, the myelinated fibers in the hippocampi of young (6 months), middle‐aged (18 months), and old‐aged (28 months) male Sprague‐Dawley rats were studied with transmission electron microscope and stereological methods, following spatial learning tests in a Morris water maze. The results showed that hippocampus‐dependent spatial learning was impaired in old‐aged rats but that the total volume, length, and mean diameter of the myelinated fibers in the hippocampus, as well as the hippocampal volume, remained constant during the normal aging process. Our results suggest that the age‐related decline in hippocampus‐dependent spatial learning is not attributable to myelinated fiber changes in the hippocampus and that other, undetermined factors are responsible. Anat Rec, 297:1490–1497, 2014. © 2014 Wiley Periodicals, Inc.     

Age‐Associated Changes of the Mandibular Foramen Position in Anteroposterior Dimension and of the Mandibular Angle in Dry Human Mandibles

The effect of age on the anteroposterior (A‐P) position of the mandibular foramen (MF) and on the size of the gonial angle (GA) was evaluated in this study. From an Israeli Bedouin population, 121 dry mandibles with primary (36), mixed (26), and permanent dentitions (59) were analyzed. The A‐P position of the MF perpendicular to the posterior border of the ramus was measured with a digital caliper. A mandibulometer was used to evaluate the GA. The MF distance from the posterior border of the ramus increased significantly with age by 66% from primary (7.75 mm) to permanent (12.9 mm; P < 0.001). Similarly, the MF distance from the posterior border of the ramus relative to the total ramus width in A‐P dimension increased significantly (21.4%) with altered dentitions from primary (0.28) to late permanent dentition (0.34; P < 0.001). The GA decreased significantly with age from 140.17° ± 5.9° (primary dentition) to 123.61° ± 6.9° (late permanent dentition; P < 0.001). The anterior movement of the MF and the decreased size of the GA that occurred with changing dentition were related to growth process. The MF moves anteriorly, and the GA decreases with age. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Seasonal Morphological Variations and Age‐Related Changes of the Seminal Vesicle of Viscacha (Lagostomus maximus maximus): An Ultrastructural and Immunohistochemical Study

The viscacha is a seasonal rodent that exhibit an annual reproductive cycle with periods of maximum reproductive activity and gonadal regression. We studied seasonal variations in the morphology and cellular population of the seminal vesicles (SVs) during both periods and in impuber animals. Seminal vesicles were studied by light and electronic microscopy. Measurements of epithelial height, nuclear diameter, luminal diameter, and muscular layer were performed. Also, we studied the distribution of androgen receptors (AR) in this gland during the reproductive cycle and in impuber animal. During gonadal regression, principal and clear cells showed signs of reduced functional activity. These were characterized by an epithelium of smaller height, irregular nuclei, and cytoplasm with few organelles, dilated cisterns, and glycogen granules. In impuber animals, the principal cells showed large nuclei with chromatin lax and cytoplasm with small mitochondria, poorly developed Golgi apparatus, and granules of glycogen. On the other hand, the cells exhibited seasonal variations in the distribution and percentage of immunolabeled cells to AR throughout the annual reproductive cycle. During the gonadal regression period, glandular mucosa exhibited numerous epithelial cells with intense nuclear staining. However, fibromuscular stromal cells were weakly positive for AR in contrast to what was observed during the activity period. Considering that testosterone values are lower in adult animals during the period of gonadal regression and in impuber animals, our immunohistochemical results show a significant correlation with the percentage of AR‐immunopositive cells. In conclusion, these results demonstrate that the structure of the SVs changes in the activity period of viscacha, probably because of elevated levels of testosterone leading to an increase in the secretory activity of epithelial cells. Anat Rec,, 2012. © 2012 Wiley Periodicals, Inc.     

Age‐related dermal collagen changes during development,maturation and ageing – a morphometric and comparative study

The tissue organisation of dermal collagen is gaining importance as a contributing factor both in development and ageing, as well as in skin maturation processes. In this work we aim to study different representative parameters of this structural organisation in 45 human skin samples of assorted ages, by means of image analysis. The variation of these parameters on the basis of age was assessed using several regression models (linear, quadratic and cubic). The area occupied by collagen was significantly reduced as a function of age in the papillary dermis (R² = 0.437, P < 0.0001), as well as the thickness of the collagen bundles (R² = 0.461, P < 0.0001), following statistical models of cubic and quadratic regression, respectively. The width of the papillary dermis increased in a significant manner over a linear regression model (R² = 0.26, P < 0.0001). In the reticular dermis, the cubic regression indicated a significant decline (R² = 0.392, P = 0.002) of the area filled with collagen according to the age. Both collagen thickness and bundle orientation parameters fit a quadratic regression over the age in a significant way (R² = 0.433 and R² = 0.334, respectively, both P < 0.0001). The width of the reticular dermis followed also a significant quadratic distribution according to age (R² = 0.193, P = 0.011). These parameters could partially explain the lifelong functional changes taking place in the skin and propose a baseline providing a useful entry point for future investigation.     

Changes in Biomechanical Strain and Morphology of Rat Calvarial Sutures and Bone After Tgf‐β3 Inhibition of Posterior Interfrontal Suture Fusion

Craniofacial sutures are bone growth fronts that respond and adapt to biomechanical environments. Little is known of the role sutures play in regulating the skull biomechanical environment during patency and fusion conditions, especially how delayed or premature suture fusion will impact skull biomechanics. Tgf‐β3 has been shown to prevent or delay suture fusion over the short term in rat skulls, yet the long‐term patency or its consequences in treated sutures is not known. It was therefore hypothesized that Tgf‐β3 had a long‐term impact to prevent suture fusion and thus alter the skull biomechanics. In this study, collagen gels containing 3 ng Tgf‐β3 were surgically placed superficial to the posterior interfrontal suture (IFS) and deep to the periosteum in postnatal day 9 (P9) rats. At P9, P24, and P70, biting forces and strains over left parietal bone, posterior IFS, and sagittal suture were measured with masticatory muscles bilaterally stimulated, after which the rats were sacrificed and suture patency analyzed histologically. Results demonstrated that Tgf‐β3 treated sutures showed less fusion over time than control groups, and strain patterns in the skulls of the Tgf‐β3‐treated group were different from that of the control group. Although bite force increased with age, no alterations in bite force were attributable to Tgf‐β3 treatment. These findings suggest that the continued presence of patent sutures can affect strain patterns, perhaps when higher bite forces are present as in adult animals. Anat Rec,, 2012. © 2012 Wiley Periodicals, Inc.     

Mandibular corpus bone strain in goats and alpacas: Implications for understanding the biomechanics of mandibular form in selenodont artiodactyls

The goal of this study is to clarify the functional and biomechanical relationship between jaw morphology and in vivo masticatory loading in selenodont artiodactyls. We compare in vivo strains from the mandibular corpus of goats and alpacas to predicted strain patterns derived from biomechanical models for mandibular corpus loading during mastication. Peak shear strains in both species average 600–700 µɛ on the working side and approximately 450 µɛ on the balancing side. Maximum principal tension in goats and alpacas is directed at approximately 30° dorsocaudally relative to the long axis of the corpus on the working side and approximately perpendicular to the long axis on the balancing side. Strain patterns in both species indicate primarily torsion of the working-side corpus about the long axis and parasagittal bending and/or lateral transverse bending of the balancing-side corpus. Interpretation of the strain patterns is consistent with comparative biomechanical analyses of jaw morphology suggesting that in goats, the balancing-side mandibular corpus is parasagittally bent whereas in alpacas it experiences lateral transverse bending. However, in light of higher working-side corpus strains, biomechanical explanations of mandibular form also need to consider that torsion influences relative corpus size and shape. Furthermore, the complex combination of loads that occur along the selenodont artiodactyl mandibular corpus during the power stroke has two implications. First, added clarification of these loading patterns requires in vivo approaches for elucidating biomechanical links between mandibular corpus morphology and masticatory loading. Second, morphometric approaches may be limited in their ability to accurately infer masticatory loading regimes of selenodont artiodactyl jaws.     

Age‐dependent changes of the mandible bone throughout the lifespan in female F344/N rat

Age‐dependent changes of the mandible bone in female F344/N rats, aged 22–1196 days, were analyzed using physiological bone properties and morphology. Bone weight, bone area, bone mineral components, and bone mineral density were assessed using dual‐energy X‐ray absorptiometry. The bone weight, bone area, bone mineral components, and bone mineral density increased rapidly until approximately 150 days of age, increased gradually thereafter, and then stabilized or decreased after 910 days of age. The ratio of bone mineral components to bone weight (bone mineral ratio) increased rapidly until approximately 43 days of age and stabilized thereafter. Size of the mandible, which was measured at 13 points on mandible surface, increased with age, and the rate of change showed a similar pattern to the other parameters. From a principal component analysis on morphometric measurements, principal component 1 (size factor) increased proportionally with age, whereas principal component 2 (shape factor) decreased until approximately 88 days of age and then increased after 365 days of age. As a result, the scatter plots for principal component 1 and principal component 2 were V‐shaped, which indicates that the mandible developed in size, with deformation at younger ages, and recovered its original shape later in life. Our results revealed the occurrence of inflection points at approximately 43, 88, 150, 365, and 910 days of age. Some of these ages corresponded to transition points revealed by the age‐dependent changes of the occlusal mandibular condyle and tooth wear in the same rat.     

Effect of Enamel Prism Decussation and Chemical Composition on the Biomechanical Behavior of Dental Tissue: A Theoretical Approach to Determine the Loading Conditions to Which Modern Human Teeth are Adapted

This theoretical study explored whether the directions of loads to which modern human molars are commonly subjected to are reflected in the biomechanical behavior of the tissue itself. A detailed finite element model of a piece of decussating enamel (M³ paracone) was created, taking into account differences in crystal orientation between the prism head and the interprismatic matrix, and was tested under differently angled mediolateral loads (i.e., mimicking various stages of the chewing cycle). Second, although teeth are highly mineralized, they also contain organic material and water, while in modern humans, there are systematic differences in chemical composition from the outer enamel surface to the dentinoenamel junction. To test the biomechanical effects of this gradient in mineralization a second set of models with gradually changing properties was created and subjected to the same loads. Chemically heterogeneous enamel yielded overall lower stress levels than homogenous enamel, especially at extreme loading angles. However, the general trends regarding the increase in tensile stresses at more oblique angles, and the number of nodes exhibiting tension, were comparable between the different set‐ups. The findings support suggestions that (a) the biomechanical behavior of dental tissue is the combined result of micromorphology and chemical composition and (b) that the range of loading directions, to which teeth are normally subjected to, can be inferred from dental microanatomy. For (palaeo)biological applications, the findings suggest that the absolute strength of teeth (e.g., bite force) cannot be predicted with certainty, whereas kinematic parameters of the masticatory apparatus can. Anat Rec, 2007. © 2008 Wiley‐Liss, Inc.     

Functional SNP in 3′‐UTR MicroRNA‐Binding Site of ZNF350 Confers Risk for Age‐Related Cataract

Many studies have suggested that individual susceptibility to age‐related cataract (ARC) may be associated with DNA sequence polymorphisms affecting gene regulation. As DNA repair is implicated in ARC pathogenesis and single‐nucleotide polymorphisms (SNPs) in the 3′‐terminal untranslated region (3′‐UTR) targeted by microRNAs (miRNAs) can alter the gene function, we hypothesize that the miRNA‐binding SNPs (miRSNPs) in DNA double‐strand break repair (DSBR) and nucleotide excision repair (NER) pathways might associate with ARC risk. We genotyped nine miRSNPs of eight genes in DSBR and NER pathways in Chinese population and found that ZNF350‐ rs2278414:G>A was significantly associated with ARC risk. Even though the Comet assay of cellular DNA damage indicated that all the subtypes of ARC patients had more DNA breaks in peripheral lymphocytes than the controls independent of rs2278414 genotypes, individuals carrying the variant A allele (AA and AG) had lower ZNF350 mRNA levels compared with individuals with GG genotype. Moreover, the in vitro experiment indicated that miR‐21‐3p and miR‐150‐5p specifically downregulated luciferase reporter expression in the cell lines transfected with rs2278414 A allele compared with rs2278414 G. These results suggested that the association of SNP rs2278414 with ARC might involve an altered miRNA regulation of ZNF350.     

Biomechanical evaluation of spring system for implant-supported prosthesis: analysis by photoelasticity and extensometry

New systems are released in the odontological market with the objective of bringing improvements and advancements in the clinical success of implants and implant-supported prostheses. The distribution of tension for the bone/implant system of these new systems is important. The purpose of this work was to evaluate, by photoelastic analysis and strain gauges, the distribution of tension for the bone/implant system, using the Slim system. A photoelastic cast with an external hexagon implant was manufactured and a metal prosthesis was screwed below it, with or without the tested system. For the photoelasticity methodology, a photoelastic cast, with or without the tested system, was positioned in a circular polariscope, and axial loads of 100?N were applied to the centre of the crown. The pattern of tension generated was photographed and analysed qualitatively in an imaging programme. For the extensometry methodology, two extensometers were placed in the mesial and distal region of the implant in the photoelastic cast. The axial loads were applied to the group again, with or without the system (n?=?10). The t test of independent samples with a significance level of 5% was used for this analysis. This study demonstrated greater tension values for both the photoelastic and extensometry methods when the tested system was used. Clinical studies must be performed to evaluate the tested system because the results might not be clinically significant to a bone reabsorption.     

Branch‐Based Model for the Diameters of the Pulmonary Airways: Accounting for Departures From Self‐Consistency and Registration Errors

We examine a previously published branch‐based approach for modeling airway diameters that is predicated on the assumption of self‐consistency across all levels of the tree. We mathematically formulate this assumption, propose a method to test it and develop a more general model to be used when the assumption is violated. We discuss the effect of measurement error on the estimated models and propose methods that take account of error. The methods are illustrated on data from MRI and CT images of silicone casts of two rats, two normal monkeys, and one ozone‐exposed monkey. Our results showed substantial departures from self‐consistency in all five subjects. When departures from self‐consistency exist, we do not recommend using the self‐consistency model, even as an approximation, as we have shown that it may likely lead to an incorrect representation of the diameter geometry. The new variance model can be used instead. Measurement error has an important impact on the estimated morphometry models and needs to be addressed in the analysis. Anat Rec,, 2012. © 2012 Wiley Periodicals, Inc.