Reduced trabecular bone mineral density and cortical thickness accompanied by increased outer bone circumference in metacarpal bone of rheumatoid arthritis patients: a cross-sectional study

Introduction

The objective of this study was to assess three-dimensional bone geometry and density at the epiphysis and shaft of the third meta-carpal bone of rheumatoid arthritis (RA) patients in comparison to healthy controls with the novel method of peripheral quantitative computed tomography (pQCT).

Methods

PQCT scans were performed in 50 female RA patients and 100 healthy female controls at the distal epiphyses and shafts of the third metacarpal bone, the radius and the tibia. Reproducibility was determined by coefficient of varia-tion. Bone densitometric and geometric parameters were compared between the two groups and correlated to disease characteristics.

Results

Reproducibility of different pQCT parameters was between 0.7% and 2.5%. RA patients had 12% to 19% lower trabecular bone mineral density (BMD) (P ≤ 0.001) at the distal epiphyses of radius, tibia and metacarpal bone. At the shafts of these bones RA patients had 7% to 16% thinner cortices (P ≤ 0.03). Total cross-sectional area (CSA) at the metacarpal bone shaft of pa-tients was larger (between 5% and 7%, P < 0.02), and relative cortical area was reduced by 13%. Erosiveness by Ratingen score correlated negatively with tra-becular and total BMD at the epiphyses and shaft cortical thickness of all measured bones (P < 0.04).

Conclusions

Reduced trabecular BMD and thinner cortices at peripheral bones, and a greater bone shaft diameter at the metacarpal bone suggest RA spe-cific bone alterations. The proposed pQCT protocol is reliable and allows measuring juxta-articular trabecular BMD and shaft geometry at the metacarpal bone.     

Trabecular Architecture of the Manual Elements Reflects Locomotor Patterns in Primates

The morphology of trabecular bone has proven sensitive to loading patterns in the long bones and metacarpal heads of primates. It is expected that we should also see differences in the manual digits of primates that practice different methods of locomotion. Primate proximal and middle phalanges are load-bearing elements that are held in different postures and experience different mechanical strains during suspension, quadrupedalism, and knuckle walking. Micro CT scans of the middle phalanx, proximal phalanx and the metacarpal head of the third ray were used to examine the pattern of trabecular orientation in Pan, Gorilla, Pongo, Hylobates and Macaca. Several zones, i.e., the proximal ends of both phalanges and the metacarpal heads, were capable of distinguishing between knuckle-walking, quadrupedal, and suspensory primates. Orientation and shape seem to be the primary distinguishing factors but differences in bone volume, isotropy index, and degree of anisotropy were seen across included taxa. Suspensory primates show primarily proximodistal alignment in all zones, and quadrupeds more palmar-dorsal orientation in several zones. Knuckle walkers are characterized by having proximodistal alignment in the proximal ends of the phalanges and a palmar-dorsal alignment in the distal ends and metacarpal heads. These structural differences may be used to infer locmotor propensities of extinct primate taxa.     

Interstitial deletion of long arm of chromosome 13

The case is presented of a patient with the karyotype 46,XX,del(13q)(pter----q22::q32----qter) confirmed by densitometry and a phenotype of mental and growth deficiency, hypotonia, hypertelorism, ptosis, broad nasal bridge, protruding upper incisors, short neck, dislocation of the hip, hypoplasia of the thumbs, fusion of fourth and fifth metacarpal bones and syndactyly of toes. The findings are compared with those of well documented cases with a similar deleted segment of the long arm of chromosome 13. Although it seems obvious that a clinical syndrome for the distal deletion 13q appears to exist more studies with banded chromosomes are needed.     

Growth Arrest Lines in Long Bones of the Casas Grandes Population

Abstract

One aspect of paleopathology, the examination of growth arrest lines, is suggested as a tool in archeological interpretation. Disruption of the normal growth pattern of long bones may result in the formation of transverse lines of extra-dense bone, visible in ordinary X-rays of the bone shaft. These radio opaque lines, presumed to result from temporary growth arrest caused by illness, are described for a sample of tibias and femurs from Casas Grandes, an archeological site in northern Chihuahua, Mexico. The sex and age of each individual at the time of growth arrest is noted, and the possibility of using this information to supplement or clarify archeological data is discussed.     

Second metacarpal midshaft geometry in an historic cemetery sample

Study of bone mass at the second metacarpal midshaft has contributed to our understanding of skeletal growth and aging within and between populations and has relied extensively on noninvasive techniques and in particular radiogrammetric data. This study reports age, sex, and side variation in size and shape data acquired from direct measurement of cross-sections obtained from a large (n = 356), homogeneous skeletal sample. Correlation analysis and three-way ANOVA of size-adjusted data confirm general impressions of patterned variation in this element: males have absolutely but not necessarily relatively larger bones than females; the right side is larger than the left, though a larger than expected proportion (approximately 25%) of left metacarpals exhibits greater values than the right; and bone mass but not strength (in males) declines with age. Contrary to the widely accepted assumption of circularity for this location, direct measurement of cross-sectional geometry confirms previous biplanar radiogrammetric conclusions regarding the noncircularity of the second metacarpal midshaft and identifies a significant difference between males and females, with the latter having a more cylindrical diaphysis. Deviation of the axes of maximum and minimum bending strength associated with noncircularity suggests a distribution of bone mass to resist bending moments perpendicular to the distal palmar arch, though this conclusion awaits more robust study of the functional anatomy of the metacarpal diaphysis. Am J Phys Anthropol 106:157–167, 1998. © 1998 Wiley-Liss, Inc.     

Osteohistological insight into the early stages of growth in Mussaurus patagonicus (Dinosauria,Sauropodomorpha)

Here, we describe the bone histology of juvenile specimens of the basal sauropodomorph Mussaurus patagonicus and interpret its significance in terms of the early growth dynamics of this taxon. Thin sections from three juvenile specimens (femur length, 111–120 mm) of Mussaurus were analysed. The sampled bones consist of multiple postcranial elements collected from the Late Triassic Laguna Colorada Formation (El Tranquilo Group, Patagonia). The cortical bone is composed of fibrolamellar bone tissue. Vascularisation is commonly laminar or plexiform in the long bones. Growth marks are absent in all the examined samples. The ‘epiphyses’ of long bones are all formed by well-developed hypertrophied calcified cartilage. The predominance of woven-fibred bone matrix in cortical bones indicates a fast growth rate in the individuals examined. Moreover, given the existence of growth marks in adult specimens of Mussaurus, as in other sauropodomorphs, and assuming that the first lines of arrested growth was formed during the first year of life, the absence of growth marks in all the bones suggest that the specimens died before reaching their first year of life. Compared with the African taxon Massospondylus carinatus (another basal sauropodomorph for which the bone histology has been previously studied), it appears that Mussaurus had a higher early growth rate than Massospondylus.     

基于有限元的第5 掌骨颈骨折钢板螺钉内固定的生物力学分析

目的：应用有限元方法建立三种不同的治疗第5 掌骨颈骨折的钢板螺钉内固定模型,比较三种模型的生物力学稳定性,为 第5 掌骨颈骨折的临床早期功能康复提供参考。方法：选取一名健康青年志愿者,将CT 扫描数据导入三维有限元软件建立第5 掌骨颈骨折模型,并选取三种钢板螺钉内固定方法进行骨折固定。对三种模型施加外力荷载并进行生物力学有限元分析,对比骨 折断端的最大位移和钢板螺钉的应力分布情况。结果：方法一、二、三的第5 掌骨骨折端的最大位移分别为0.189775 mm、 0.181428 mm、0.224299 mm,以方法二的骨折端位移最小;内固定材料的最大应力分别为1.20 KPa、1.00 KPa、1.39 KPa,以方法二 的钢板螺钉应力最小。结论：采用近端三颗螺钉远端两颗螺钉的直型钢板内固定方法治疗第五掌骨颈骨折的生物力学稳定性更 好,术后早期功能锻炼的安全性更高,是治疗第5 掌骨颈骨折的理想内固定方法。     

The functional morphology of the cercopithecoid wrist and inferior radioulnar joints, and their bearing on some problems in the evolution of the Hominoidea.

The cercopithecoid wrist joint differs from the wrist joints of hominoids in several ways. The distal ulna, the distal radius, the pisiform, the triquetrum, the hamate, and the base of the fifth metacarpal are on the one hand remarkably alike among cercopithecoid genera, and on the other remarkably distinct from homologous bones in the Hominoidea. Functionally, the triquetrum and the pisiform, in conjuction with the ulnar styloid process, check the proximal carpal row during ulnar deviation, and are possibly important in stabilizing the wrist during dorsiflexion as well. The head of the ulna almost certainly betokens a range of radioulnar supination in cercopithecoids that is substantially less than is to be found in any of the hominoid genera. The articulation between the hamate bone and the base of the fifth metacarpal allows for considerable dorsiflexion in the Cercopithecoidea; this potential was not evidenct in any of the hominoids examined. Behaviorally, the cercopithecoid wrist can most profitably be viewed as an adaptation for a quadrupedal life style involving dorsiflexion of the wrist and palmigrade/digitigrade substrate contact. The hominoid wrist joint is not adapted for such a behavioral potential.     

A new fossil bird from the Early Cretaceous of Gansu Province,northwestern China

We report on the discovery of an Early Cretaceous bird from northwestern Gansu Province, in northwestern China. Represented by a nearly complete left wing and shoulder girdle the size of a rock dove, the new bird was quarried from laminated yellowish mudstones of the Xiagou Formation (Xinminpu Group) near Changma, in the Jiuquan area. These deposits have previously yielded the only known specimen of Gansus yumenensis, a basal ornithuromorph represented by the distal half of a hind limb with long and slender digits. Several derived characters of the new occurrence supports its allocation within Enantiornithes: (1) a convex lateral margin of the coracoid, (2) a minor metacarpal that projects distally more than the major metacarpal and (3) a proximal phalanx of the major digit longer than the intermediate (second) phalanx. The general proportions of the wing suggest it was a flier comparable to most other known enantiornithine birds. Although, direct comparisons between the new fossil and Gansus are not possible, phylogenetic based inferences supports their placement into two different clades. While the new fossil falls definitively within the enantiornithines, G. Yumenensis falls within the ornithuromorphs. The new occurrence thus adds to the taxonomic diversity of Early Cretaceous birds from Gansu Province in particular and central Asia in general.     

Associations between the rates of maturation of the bones of the hand-wrist

Skeletal maturation rates for the age interval 3 to 13 years were analyzed using bone-specific assessments (Greulich-Pyle) of serial radiographs of 40 children. The mean rates of skeletal maturation resembled those of the population from which the atlas standards had been derived. There was a linear trend of skeletal age against chronological age for most bones in each sex. Regression lines were fitted to these data and the b values of the regression lines were calculated. Communality indices were calculated from an intercorrelation matrix of these b values. There was a statistically significant rank order correlation between the sexes in the communality indices. They tended to be higher in the girls than in the boys and were relatively low for the radius, ulna and carpals. Communality indices within groups of bones were high in all rows, especially the metacarpals, but in each sex they were comparatively low in the first ray (metacarpal plus the phalanges of the corresponding digit) and in the fifth ray of the boys. Neighborhood effects on the levels of association of maturation rates were present, particularly in the carpus, but marginal effects were not noted.     

The differential frequency of preservation of early hominid wrist and hand bones

A survey of hominid hand and wrist bones of Plio-Pleistocene fossil hominid sites in Africa was undertaken. There are 101 specimens in total, from 7 sites. Carpals are most rarely preserved, but certain elements such as the capitate tend to be more frequently preserved than others. There is a preservation rate cline from proximal to distal in the hand, proximal elements (metacarpals) being numerically better preserved than the distal elements (proximal, middle and distal phalanges, in that order of preservation). The proportion of complete, or nearly complete hand and wrist bones is greater in the distal than in the proximal elements. There is no statistical difference in the frequency of preservation of left and right sides, or in the frequency of preservation of proximal and distal ends of individual bones, although there is a tendency for proximal ends to occur more frequently than distal ends. The incidence of hand and wrist bones in fossil deposits is low compared with that of other post-cranial skeletal elements (with the exception of foot bones, where the incidence is similar). This could be accounted for by depositional factors, but preparation techniques and differential collection of specimens may play a role.     

Assembly and fate of basal bodies in the colourless phytoflagellate Polytoma papillatum

Summary— The morphogenesis of basal bodies is described in the phytoflagellate Polytoma papillatum. The observations are based on the analysis of ultrathin serial sections through the flagellar apparatus of interphase, mitotic, and postmitotic cells using transmission electron microscopy. Formation of new basal bodies starts in prometaphase. Individual A-subfibres develop orthogonally to the long axis of mature basal bodies. The microtubules assemble at the surface of an annulus of amorphous material. By telophase, a complete cylinder of A-subfibres with a length of approximately 300 nm has formed. Although the proximal ends of these new probasal bodies are detached from the mature basal bodies, prominent reorientation of the probasal bodies does not occur. They remain with their proximal ends in the vicinity of mature basal bodies. In daughter cells with probasal bodies around 400 nm long, the assembly of microtubular triplets is initiated. B- and C-subfibres first show up distal from the mature basal bodies and may elongate towards them. Thus, A-subfibres on the one side and B- and C-subfibres on the other appear to growt with opposite polarity. If A-subfibres grow at their plus ends, B- and C-subfibres elongate at their minus ends. The latter is unusual in comparison with individual cytoplasmic and spindle microtubules. Possible the presence of a lateral template in the form of the A-subfibres is responsible for the deviating growth characteristics of the incomplete B- and C-subfibres. In interphase cells, the mature basal bodies extend into long flagella. The new basal bodies remain devoid of flagella and are less than 85 nm long. Thus, they have shortened relative to their precursors in mitotic and postmitotic cells. At the onset of a new division cycle, the flagellate basal badies shed their flagella. The breaking point is at the triplet-doublet transition of the flagellum.     

Metacarpal synostosis: a simple classification and a new treatment technique

The current classification of metacarpal synostosis is based on the extent of the synostosis. The authors propose a new classification that takes into account the shape of the metacarpal bones, the curvature of the epiphysis, and the discrepancy in length between the two bones. This classification provides better guidelines for the correction of all components of the deformity. The classification is based on the authors' observations of and experience with 36 cases of metacarpal synostosis; 13 of the deformities were surgically corrected. The I-shaped deformity, whether with distinct (type d) or fused (type f) metacarpophalangeal joints, does not require surgical correction. The U-shaped deformity has parallel epiphysis and does not require surgery unless the two metacarpals are asymmetrical in length (type a) or tightly fused (type t); in these cases, simple lengthening or widening of the space with a bone graft is sufficient. Y-shaped synostosis should be separated whether the branches are symmetrical or asymmetrical, the latter having one branch shorter than the other. Because the epiphyses are already divergent, simple separation does not effectively correct Y-shaped synostosis. The authors propose an osteotomy to isolate a trapezoidal segment of bone from the bifurcation. The isolated bone segment is then reversed in the proximal-distal direction to provide a "plateau" upon which the two distal metacarpals can be realigned. Two cases of Ys (symmetrical) synostosis were successfully treated with this technique; one case of Ya (asymmetrical) synostosis also required distraction lengthening of the shorter metacarpal to achieve an excellent result. One of the most difficult types of metacarpal synostosis to treat is k-shaped synostosis, observed only between the fourth and fifth metacarpals; in this type, the head of the short fifth metacarpal abuts the metaphysis of the fourth. Osteotomy and distraction lengthening provide predictable results for correction of this deformity. The authors suggest that k-shaped synostosis might represent a late evolution of untreated Ua synostosis.     

Tubular hand bone growth during the latter half of the prenatal period: an allometric analysis

The growth of the 19 tubular hand bones from fetal months 5 to 9 was studied by the allometric method. The hand bones were carefully dissected under a low power stereoscopic microscope. The length and breadth of all bones was found to be monophasic in relation to crown-rump length. In general, maximum bone and ossified shaft lengths in the same row group demonstrate similar allometric coefficients. The specific growth rate of ossified shaft length for all fetal hand bones is greater than the growth rate of maximum length. The highest allometric coefficients for both maximum length and ossified shaft length were obtained from the middle phalanges. The shape of the metacarpals and distal phalanges becomes thinner, while the other bones become thicker or maintain their length-breadth ratio. The relative growth pattern of the first proximal phalanx differed from the middle phalangeal group of the other digits. This suggests that current nomenclatures for the three bones of the pollex is appropriate.     

Longevity and growth rate estimates for a polar dinosaur: a Pachyrhinosaurus (Dinosauria: Neoceratopsia) specimen from the North Slope of Alaska showing a complete developmental record

Our knowledge of growth dynamics in large ceratopsian dinosaurs is very poor, in part, due to the paucity of quantifiable age markers such as growth lines in their bones. We sought marker-based, osteohistological evidence for ceratopsid age structure from high Arctic paleolatitudes based on the observations that: (1) extant mammals from high latitudes better express growth lines in their hard tissues than those from lower latitudes, and (2) the occurrence of accentuated growth banding in teeth from Arctic dinosaurs. We examined the long bones in the specimens of Pachyrhinosaurus sp. from the early Maastrichtian of northern Alaska, and found conspicuous osseous banding. Histological analysis of the spacing, structure, pattern and numbers of these bands in the femur of a very large specimen suggests that they are not a taphonomic artefact, rather they appear to reflect annual growth cycling. Counts and measurements of the growth zones suggest that the animal showed rapid linear growth early in ontogeny, sexual maturity in perhaps the 9th year of life, and that it died in the 19th year of life. Our data adds to a growing body of evidence that a genetically distinct northern dinosaurian fauna existed at high paleolatitudes in Alaska during the Late Cretaceous.     

Directed microtubule growth, +TIPs, and kinesin-2 are required for uniform microtubule polarity in dendrites

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Highlights? Uniform microtubule polarity in dendrites requires directed microtubule growth ? Growing microtubule plus ends use stable microtubules as directional tracks ? Dendrite microtubule polarity is disrupted when kinesin-2 and +TIP levels are reduced ? Kinesin-2 attachment to microtubule plus ends might allow directed microtubule growth     

Profilin is required for viral morphogenesis, syncytium formation, and cell-specific stress fiber induction by respiratory syncytial virus

Background

Bacterial macrofibers twist as they grow, writhe, supercoil and wind up into plectonemic structures (helical forms the individual filaments of which cannot be taken apart without unwinding) that eventually carry loops at both of their ends. Terminal loops rotate about the axis of a fiber's shaft in contrary directions at increasing rate as the shaft elongates. Theory suggests that rotation rates should vary linearly along the length of a fiber ranging from maxima at the loop ends to zero at an intermediate point. Blocking rotation at one end of a fiber should lead to a single gradient: zero at the blocked end to maximum at the free end. We tested this conclusion by measuring directly the rotation at various distances along fiber length from the blocked end. The movement of supercoils over a solid surface was also measured in tethered macrofibers.

Results

Macrofibers that hung down from a floating wire inserted through a terminal loop grew vertically and produced small plectonemic structures by supercoiling along their length. Using these as markers for shaft rotation we observed a uniform gradient of initial rotation rates with slopes of 25.6°/min. mm. and 36.2°/min. mm. in two different fibers. Measurements of the distal tip rotation in a third fiber as a function of length showed increases proportional to increases in length with constant of proportionality 79.2 rad/mm. Another fiber tethered to the floor grew horizontally with a length-doubling time of 74 min, made contact periodically with the floor and supercoiled repeatedly. The supercoils moved over the floor toward the tether at approximately 0.06 mm/min, 4 times faster than the fiber growth rate. Over a period of 800 minutes the fiber grew to 23 mm in length and was entirely retracted back to the tether by a process involving 29 supercoils.

Conclusions

The rate at which growing bacterial macrofibers rotated about the axis of the fiber shaft measured at various locations along fibers in structures prevented from rotating at one end reveal that the rate varied linearly from zero at the blocked end to maximum at the distal end. The increasing number of twisting cells in growing fibers caused the distal end to continuously rotate faster. When the free end was intermittently prevented from rotating a torque developed which was relieved by supercoiling. On a solid surface the supercoils moved toward the end permanently blocked from rotating as a result of supercoil rolling over the surface and the formation of new supercoils that reduced fiber length between the initial supercoil and the wire tether. All of the motions are ramifications of cell growth with twist and the highly ordered multicellular state of macrofibers.     

A partial skeleton of Geotrypus antiquus (Talpidae, Mammalia) from the Late Oligocene of the Enspel fossillagerst?tte in Germany

The partial skeleton of a young adult Geotrypus antiquus (de Blainville 1840) from the Upper Oligocene (MP 28) found in Enspel comprises the skull with both mandibles, distal ends of both scapulae, left clavicula, humeri, ulnae and radii of both sides, various elements of the hand, some vertebrae, ribs, and the left femur. For the first time, the previously postulated association between dentition and postcranial elements can be confirmed. The skeleton exhibits strong adaptations for a subterranean life, similar to modern fossorial moles. The humerus is wide with a large pectoral process. The wing-like greater and lesser tuberosities, teres tubercle, and distal epicondylus are clearly developed. The metacarpals and phalanges are broad and stout. There are several sesamoid bones in the broad digging hand, including a prepollex (os falciforme). The preserved bones allowed the forelimb of G. antiquus to be reconstructed. Previous finds of G. antiquus have mainly been from France, with a few specimens from Switzerland and southern Germany. The specimen from Enspel is the northernmost record. A cladistic analysis, based on the matrix of Sánchez-Villagra et al. (Cladistics 22:59?C88, 2006), confirms the basal position of Geotrypus within the Old World moles (Talpini).     

Kinetochores Generate Microtubules with Distal Plus Ends: Their Roles and Limited Lifetime in Mitosis

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Highlights? A short-lived population of kinetochore-derived microtubules (MTs) has distal plus ends ? These MTs are generated in early mitosis and regulated by Stu2 ? They interact with spindle pole-derived MTs before kinetochore attachment ? Once kinetochores attach to spindle-pole MTs, the short-lived MT population disappears     

Transverse (Harris) lines in irish archaeological remains

Transverse lines were examined in 633 long bones from 73 individuals exhumed from two burial sites in the Republic of Ireland: Waterford City and Tintern Abbey. The burials cover four distinct periods between the 11th and 17th centuries. Lines were most numerous in the tibia, especially in the distal segment, and were not seen in the humerus nor the proximal part of the femur. The number of lines varied between the proximal and distal segments of each long bone, and though apparently equal in number across the midline, there were significant differences in the incidence of lines between corresponding pairs of bones. Thus, it is unwise to rely on the results of a single bone or one type of long bone alone either to indicate the health status of an individual, or as the basis for assessing the health status of a small population. Such results should be used only in association with other indicators. © 1996 Wiley-Liss, Inc.