An apparently phylogeny-independent method for identification of skeletal (longitudinal) growth cessation (skeletal maturity) in birds

Identification of skeletal maturity is of interest as a measure of species longevity and for identifying its maximal achievable size/mass. Measurement of age on the basis of growth arrest/accentuation lines and external fundamental system evidences cessation or at least extreme slowing of circumferential bone growth. Such intramembranous (periosteal)-derived growth is distinct from the endochondral ossification responsible for longitudinal growth and therefore achievable organismal size/mass. As subchondral transcortical channels are required for nourishment, their loss should identify cessation of longitudinal growth. Predicated on phylogenetic bracketing/relationship and shared anatomical structures with and without growth plates, birds represent an appropriate model for the study of dinosaur ontogeny. Persistence of transcortical subchondral channels in the long bones of birds are examined at ×100–200 magnification and correlated with bone length. Transcortical channels are present in subchondral articular surfaces, but disappear when terminal longitudinal growth is achieved. Articular vascular channels perforating articular surfaces from within the bone are detected. Loss of penetrating channels is interpreted as evidence of skeletal growth cessation, identifying the longitudinal bone length at which skeletal growth cessation has been achieved. The current study provides evidence that maximal bone length does correlate with endochondral cessation growth. Failure of circumferential growth reduction/cessation to correlate with bone length may be related to lack of synchronicity of periosteal-based circumferential growth with the endochondral process responsible for bone lengthening. Loss/closure of articular vascular channels may be the most reliable measure of a bird's achievement of maximal growth (indicating cessation of appendicular element lengthening).     

Thyroid hormone and the growth plate

Thyroid hormone was first identified as a potent regulator of skeletal maturation at the growth plate more than forty years ago. Since that time, many in vitro and in vivo studies have confirmed that thyroid hormone regulates the critical transition between cell proliferation and terminal differentiation in the growth plate, specifically the maturation of growth plate chondrocytes into hypertrophic cells. However these studies have neither identified the molecular mechanisms involved in the regulation of skeletal maturation by thyroid hormone, nor demonstrated how the systemic actions of thyroid hormone interface with the local regulatory milieu of the growth plate. This article will review our current understanding of the role of thryoid hormone in regulating the process of endochondral ossification at the growth plate, as well as what is currently known about the molecular mechanisms involved in this regulation.     

Early fibrodysplasia ossificans progressiva-like lesion formation in nude mice following implantation of lymphoblastoid cells from FOP patients

Fibrodysplasia ossificans progessiva (FOP) is a genetic disease of progressive, heterotopic ossification, resulting in profound decreased mobility. To investigate the pathophysiology of this condition, lymphoblastoid cells (LCLs) derived from patients with FOP or unaffected family members were implanted subcutaneously into athymic (nude) mice. Cells from unaffected individuals persisted as small masses with little evidence of a fibrotic or angiogenic response. In contrast, cells from patients with FOP gave rise to palpable, solid, fibrotic cellular masses in the animals. Histological and immunohistochemical evaluation revealed that FOP cells proliferated in the host and induced a fibrotic and angiogeneic response similar to the early-stage FOP lesions in patients, but did not progress to form ettopic cartilage or bone. These results de monstrate that lymphoblastoid cells from patients with FOP induce early preosseous FOP-like lesions in mice, but are not sufficient to induce heterotopic ossification in immunocompromised host animals. Implantation of FOP-derived cells in nude mice provides a useful model system for examining the earliest stages of the disease.     

Osificación heterotópica de las piernas en un varón

Heterotopic ossification is an uncommon disorder that consists of deposition of ectopic bone outside the extraskeletal tissues. In the skin, it can be primary, in association with genetic syndromes, or be secondary to different disorders. The latter include subcutaneous ossification of the legs in chronic venousinsufficiency, an infrequent and unrecognized complication. We report the case of a patient with subcutaneous ossification of both legs secondary to venous insufficiency and review the literature.     

Clonal precursor of bone,cartilage, and hematopoietic niche stromal cells

Organs are composites of tissue types with diverse developmental origins, and they rely on distinct stem and progenitor cells to meet physiological demands for cellular production and homeostasis. How diverse stem cell activity is coordinated within organs is not well understood. Here we describe a lineage-restricted, self-renewing common skeletal progenitor (bone, cartilage, stromal progenitor; BCSP) isolated from limb bones and bone marrow tissue of fetal, neonatal, and adult mice. The BCSP clonally produces chondrocytes (cartilage-forming) and osteogenic (bone-forming) cells and at least three subsets of stromal cells that exhibit differential expression of cell surface markers, including CD105 (or endoglin), Thy1 [or CD90 (cluster of differentiation 90)], and 6C3 [ENPEP glutamyl aminopeptidase (aminopeptidase A)]. These three stromal subsets exhibit differential capacities to support hematopoietic (blood-forming) stem and progenitor cells. Although the 6C3-expressing subset demonstrates functional stem cell niche activity by maintaining primitive hematopoietic stem cell (HSC) renewal in vitro, the other stromal populations promote HSC differentiation to more committed lines of hematopoiesis, such as the B-cell lineage. Gene expression analysis and microscopic studies further reveal a microenvironment in which CD105-, Thy1-, and 6C3-expressing marrow stroma collaborate to provide cytokine signaling to HSCs and more committed hematopoietic progenitors. As a result, within the context of bone as a blood-forming organ, the BCSP plays a critical role in supporting hematopoiesis through its generation of diverse osteogenic and hematopoietic-promoting stroma, including HSC supportive 6C3(+) niche cells.     

骨周与关节改变对氟骨症诊断及分型分度意义的评价

本文对18岁以上525例地方性氟骨症和41例正常对照组人群X线片的骨周和关节改变进行了分析。结果表明,骨质改变在先,骨周改变在后,20岁以下无骨周改变,20岁以上随着年龄的增大,骨周骨化阳性率及严重程度均不断增加。因此,对氟骨症诊断及分度的价值也相应提高。关节改变与骨周改变基本上呈平行关系,由于其特异性较差,故诊断价值次于骨周;硬化性骨周和关节改变的阳性率略低于疏松型和混合型,混合型中极度骨软化者骨周骨化不易显现。     

广泛性特发性肥大性骨病与椎管狭窄症

报告了１２例广泛性特发性肥大性骨病所致椎管狭窄伴神经功能障碍而手术治疗的病例，其中颈椎７例，胸椎４例，腰椎１例。文章讨论了该病的诊断、鉴别诊断、治疗及与后纵韧带骨化的关系。     

Surgical outcomes in inferior recurrences of rhegmatogenous retinal detachment

AIM: To analyze the anatomical and functional outcomes in the inferior recurrences of rhegmatogenous retinal detachment (RRD) depending on the surgical approach.METHODS: Eighty-one eyes of 81 patients (47 males and 34 females with a mean age of 54.8±14.1y) who demonstrated at least one inferior recurrence of RRD were included in this retrospective study. All patients were categorized as having received either circular scleral buckling (SB), pars plana vitrectomy (PPV), a combination of SB and PPV (SB+PPV), PPV with retinotomy (PPV+RT), or PPV+RT and short-term postoperative perfluorocarbon liquid tamponade (PPV+RT+pPFCL). All cases were followed up until successful retinal reattachment or third recurrence. The primary outcome measures were the achievement of the surgical goal without recurrence of RRD and best-corrected visual acuity (BCVA).RESULTS: After the treatment of the first recurrence, the recurrence rate in the PPV+SB group was statistically significantly lower than that of the PPV (P=0.0012), PPV+RT (P=0.028), or PPV+RT+pPFCL (P=0.047) group. There was no statistically significant difference between PPV+SB, PPV+RT, and PPV+RT+pPFCL groups in the recurrence rate after treatment of the second recurrence (42 eyes). However, there was a statistically significant (P=0.016) trend towards a decrease of recurrence rate after PPV+RT+pPFCL. There was no statistically significant improvement of BCVA in either study group (P>0.05) after both first and second recurrence surgery. The mean time follow-up was 109.0±91.0d before the first recurrence and 210.0±186.6d between previous surgery at second recurrence.CONCLUSION: Patients with first inferior recurrence of RRD may benefit from SB as an adjunct to PPV. RT and short-term pPFCL tamponade in the second recurrence may allow better anatomical outcomes, however, without functional improvement.     

巩膜环扎外加压术联合氩激光治疗陈旧性视网膜脱离

目的：观察巩膜环扎外加压术联合氩激光治疗陈旧性视网膜脱离的疗效。方法：回顾分析2007-01~2009-12经巩膜环扎外加压术联合氩激光治疗陈旧性视网膜脱离32例36眼,所选病例均为孔源性视网膜脱离合并以视网膜下膜为主的PVRC级的患者。结果：术后随访3个月~1年,视网膜完全复位25眼,4眼明显好转,2眼因PVR进展行玻璃体切割术,1眼放弃治疗。术后视力提高21眼,7眼视力不变,4眼视力下降。结论：巩膜环扎外加压术联合氩激光治疗陈旧性视网膜脱离损伤小,操作简单,并发症少,疗效满意。