Cambium Layer Research Articles

ПАТОМОРФОЛОГИЧЕСКАЯ ХАРАКТЕРИСТИКА БРОНХОЛЕГОЧНОГО АППАРАТА У ПОГИБШИХ НОВОРОЖДЕННЫХ С ВРОЖДЕННОЙ ЦИТОМЕГАЛОВИРУСНОЙ ИНФЕКЦИЕЙ

The aim of the research was to study a morphological structure of airway and respiratory parts of lungs in 36 full-term newborns who died at the 2-5th day of life. The main group included 16 died newborns with the inborn cytomegalovirus infection who were diagnosed with moderate to severe cerebral ischemia with hypertension-hydrocephalic syndrome, pseudocysts of the blood vessels plexus, subependymal and subarachnoid haemorrhages, monocytosis, vesiculitis, pneumonia, hepatitis and meningocephalitis against intrauterine hypoxia and chronic subcompensated placental insufficiency. The comparison group consisted of 20 newborns whose mothers during the gestation period did not have acute respiratory viral infections, moderate and severe somatic and obstetrical pathology. The cause of their death was a birth trauma, intranatal and postnatal hypoxia. Describing lungs the following morphologic features were emphasized: 1) the changes of the general composition of the organ; 2) the state of the lumen of the large, medial and small bronchi; 3) the reaction of the epithelial lining, conjunctive tissue and the blood channel of the bronchial tree and aero-hematic barrier. As a result of the studies it was found out that in the newborns of the main group in comparison with the children of the comparison group in the lumen of large bronchi there was a rare case of mucus, there were often found erythrocytes and desquamated epithelial cells. Only infected children were found to have leucocytes. More intensified were alterative processes in epithelial cells; there were often found cells of the bronchial epithelium without ciliary structures, desquamation of highly differential ciliary and goblet cells, cell elements with a small hyperchromic nucleus and light cytoplasm in the cambial layer, sharply expressed vascular congestion, proliferative changes in the bronchial epithelium as well as hydropic-hemorrhagic and aspiration syndromes. Pneumonia and signs of the virus metamorphosis were diagnosed only in the main group.

Evidence That Rat Chondrocytes Can Differentiate Into Perichondrial Cells.

ABSTRACTDuring early bone formation, mesenchymal cells condense and then differentiate into collagen type II‐expressing chondrocytes that make up the cartilaginous bone anlagen. This anlage then becomes enclosed by the perichondrium. The mechanisms by which the perichondrium forms are not known. The purpose of this study was to determine whether epiphyseal chondrocytes can differentiate into perichondrial cells. Novel perichondrium markers were identified by expression microarray of microdissected rat perichondrium and growth plate cartilage. A dissection method that allowed for removal of contaminating perichondrium was developed and the absence was confirmed by histological examination and by expression of perichondrium markers. Perichondrium formation surrounding chondrocyte pellets was studied using histology, real‐time PCR, and in situ hybridization for chondrocyte and perichondrium markers. Cultured chondrocyte pellets developed an exterior perichondrium‐like layer. This surrounding tissue did not express chondrocyte markers, collagen‐type II and type X, as assessed by in situ hybridization. Instead, perichondrium markers, periostin, Dickkopf 3 (Dkk3), roundabout 2, cadherin 2, L‐galectin 1 (Lgals1), and thrombospondin 2 (Thbs2) were upregulated following formation of the perichondrium‐like layer as assessed by real‐time PCR. Interestingly, markers specific for the cambium layer, Dkk3, Thbs2, and Lgals1, but not for the fibrous layer, collagen‐type XIV and decorin, were upregulated. The findings suggest that epiphyseal chondrocytes of postnatal animals retain the potential to differentiate into perichondrial cells, supporting the hypothesis that the perichondrium originates from collagen type II‐expressing chondrocytes at the periphery of the cartilaginous bone template. © 2018 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Isolation of Mesenchymal Stem Cells from Human Alveolar Periosteum and Effects of Vitamin D on Osteogenic Activity of Periosteum-derived Cells.

Mesenchymal stem cells (MSCs) are present in a variety of tissues and can be differentiated into numerous cell types, including osteoblasts. Among the dental sources of MSCs, the periosteum is an easily accessible tissue, which has been identified to contain MSCs in the cambium layer. However, this source has not yet been widely studied. Vitamin D3 and 1,25-(OH)2D3 have been demonstrated to stimulate in vitro differentiation of MSCs into osteoblasts. In addition, vitamin C facilitates collagen formation and bone cell growth. However, no study has yet investigated the effects of Vitamin D3 and Vitamin C on MSCs. Here, we present a method of isolating MSCs from human alveolar periosteum and examine the hypothesis that 1,25-(OH)2D3 may exert an osteoinductive effect on these cells. We also investigate the presence of MSCs in the human alveolar periosteum and assess stem cell adhesion and proliferation. To assess the ability of vitamin C (as a control) and various concentrations of 1,25-(OH)2D3 (10-10, 10-9, 10-8, and 10-7 M) to alter key mRNA biomarkers in isolated MSCs mRNA expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), core binding factor alpha-1 (CBFA1), collagen-1, and osteocalcin (OCN) are measured using real-time polymerase chain reaction (RT-PCR).

Drought Sensitivity of Norway Spruce at the Species' Warmest Fringe: Quantitative and Molecular Analysis Reveals High Genetic Variation Among and Within Provenances.

Norway spruce (Picea abies) is by far the most important timber species in Europe, but its outstanding role in future forests is jeopardized by its high sensitivity to drought. We analyzed drought response of Norway spruce at the warmest fringe of its natural range. Based on a 35-year old provenance experiment we tested for genetic variation among and within seed provenances across consecutively occurring strong drought events using dendroclimatic time series. Moreover, we tested for associations between ≈1,700 variable SNPs and traits related to drought response, wood characteristics and climate-growth relationships. We found significant adaptive genetic variation among provenances originating from the species’ Alpine, Central and Southeastern European range. Genetic variation between individuals varied significantly among provenances explaining up to 44% of the phenotypic variation in drought response. Varying phenotypic correlations between drought response and wood traits confirmed differences in selection intensity among seed provenances. Significant associations were found between 29 SNPs and traits related to drought, climate-growth relationships and wood properties which explained between 11 and 43% of trait variation, though 12 of them were due to single individuals having extreme phenotypes of the respective trait. The majority of these SNPs are located within exons of genes and the most important ones are preferentially expressed in cambium and xylem expansion layers. Phenotype-genotype associations were stronger if only provenances with significant quantitative genetic variation in drought response were considered. The present study confirms the high adaptive variation of Norway spruce in Central and Southeastern Europe and demonstrates how quantitative genetic, dendroclimatic and genomic data can be linked to understand the genetic basis of adaptation to climate extremes in trees.

The Changing Sensory and Sympathetic Innervation of the Young, Adult and Aging Mouse Femur

Although bone is continually being remodeled and ultimately declines with aging, little is known whether similar changes occur in the sensory and sympathetic nerve fibers that innervate bone. Here, immunohistochemistry and confocal microscopy were used to examine changes in the sensory and sympathetic nerve fibers that innervate the young (10 days post-partum), adult (3 months) and aging (24 months) C57Bl/6 mouse femur. In all three ages examined, the periosteum was the most densely innervated bone compartment. With aging, the total number of sensory and sympathetic nerve fibers clearly declines as the cambium layer of the periosteum dramatically thins. Yet even in the aging femur, there remains a dense sensory and sympathetic innervation of the periosteum. In cortical bone, sensory and sympathetic nerve fibers are largely confined to vascularized Haversian canals and while there is no significant decline in the density of sensory fibers, there was a 75% reduction in sympathetic nerve fibers in the aging vs. adult cortical bone. In contrast, in the bone marrow the overall density/unit area of both sensory and sympathetic nerve fibers appeared to remain largely unchanged across the lifespan. The preferential preservation of sensory nerve fibers suggests that even as bone itself undergoes a marked decline with age, the nociceptors that detect injury and signal skeletal pain remain relatively intact.

The Regulatory Mechanism of MLT/MT1 Signaling on the Growth of Antler Mesenchymal Cells.

Melatonin (MLT) plays an important role in regulating the physiological cycle of seasonal breeding animals. Melatonin receptor I (MT1) is effectively expressed in the cambium layer of deer antler. However, the function and metabolic mechanism of MLT/MT1 signaling in the mesenchymal cells of sika deer remain to be further elucidated. In this work, we detected the effects of MLT/MT1 signaling on mesenchymal cells proliferation and the interaction between MLT/MT1 and IGF1/IGF1-R signaling. The results show that (1) deer antler mesenchymal cells actually express MT1; (2) exogenous melatonin significantly promotes mesenchymal cells proliferation, while MT1 knock-down significantly impairs the positive effects of melatonin; and (3) melatonin significantly enhanced IGF1/IGF1-R signaling, as both the expression of IGF1 and IGF-1R increased, while MT1 knock-down significantly decreased IGF1-R expression and IGF1 synthesis. In summary, these data verified that MLT/MT1 signaling plays a crucial role in antler mesenchymal proliferation, which may be mediated by IGF1/IGF1-R.

Effect of Anatomical Structure of Shoots in Different Flowering Phase on Rhizogenesis of Once-blooming Roses

The research was conducted on five once-blooming different origin historical roses. The aims were establishing differences in the anatomical structure of shoots taken in four maturity stages and their natural ability to roots creating. There were hypothesized, that the changes in anatomical structure occur in the time of flowering and may affect the ability of rhizogenesis. Single node one leaf cuttings of chosen cultivars were cut from shoots in four maturity phases: flower buds closed, all flowers open, just after and 7-14 days after petal fall. The cuttings were planted in multipot trays in peat substrate without using rooting stimulators. The anatomical structure of shoots in the place of rhizogenesis were observed, the width of xylem layer and cambial zone, diameter of vascular cells were measured. The percentage of rooted cuttings and forming only a callus were counted. Adventitious roots appeared probably in the cambium zone, pith rays, and also in the zone of phloem and pericycle. The anatomic structure of shoots changes during the period of flowering and influences rooting percentage and the percent of cuttings which developed callus only. The width of the cambium layer of shoots influences the width of the wood layer in all cultivars. The rise of width of cambium tissue have an effect of increase of percentage of cuttings forming a callus only in ‘Hurdals’ and ‘Maiden’s Blush’. The width of the cambium layer in shoots enlarges during full blooming in four of the studied cultivars (‘Hurdals’, ‘Maiden’s Blush’, ‘Mousseuse Rouge’, ‘Semiplena’) and in one it stays at the same level for the whole duration of the experiment (‘Duchesse d’Angoulême’). The specifying in practice the period of taking rose cuttings, individual properties of cultivars and phenological phase of shoot should be taken into consideration.

Artificial periosteum in bone defect repair—A review

Periosteum is a thin membrane that encases the surfaces of most bones. It is composed of an outer fibrous layer contains longitudinally oriented cells and collagen fibers and an inner cambial layer that consists of multipotent mesenchymal stem cells (MSCs) and osteogenic progenitor cells. Periosteum has a function of regulating cell and collagen arrangement, which is important to the integrity, modelling and remodelling of bone, particularly during bone defect repair. Apart from autograft and allograft, artificial periosteum, or tissue-engineered periosteum mimicking native periosteum in structure or function, made up of small intestinal submucosa, acellular dermis, induced membrane, cell sheets, and polymeric scaffolds, and so on, has been developed to be used in bone defect repair. In this review, we classify the artificial periosteum into three approaches based on the material source, that is, native tissues, scaffold-free cell sheets and scaffold-cell composites. Mechanisms, methods and efficacy of each approach are provided. Existing obstacles and enabling technologies for future directions are also discussed.

Engineering biomimetic periosteum with \u03b2-TCP scaffolds to promote bone formation in calvarial defects of rats

BackgroundThere is a critical need for the management of large bone defects. The purpose of this study was to engineer a biomimetic periosteum and to combine this with a macroporous β-tricalcium phosphate (β-TCP) scaffold for bone tissue regeneration.MethodsRat bone marrow-derived mesenchymal stem cells (rBMSCs) were harvested and cultured in different culture media to form undifferentiated rBMSC sheets (undifferentiated medium (UM)) and osteogenic cell sheets (osteogenic medium (OM)). Simultaneously, rBMSCs were differentiated to induced endothelial-like cells (iECs), and the iECs were further cultured on a UM to form a vascularized cell sheet. At the same time, flow cytometry was used to detect the conversion rates of rBMSCs to iECs. The pre-vascularized cell sheet (iECs/UM) and the osteogenic cell sheet (OM) were stacked together to form a biomimetic periosteum with two distinct layers, which mimicked the fibrous layer and cambium layer of native periosteum. The biomimetic periostea were wrapped onto porous β-TCP scaffolds (BP/β-TCP) and implanted in the calvarial bone defects of rats. As controls, autologous periostea with β-TCP (AP/β-TCP) and β-TCP alone were implanted in the calvarial defects of rats, with a no implantation group as another control. At 2, 4, and 8 weeks post-surgery, implants were retrieved and X-ray, microcomputed tomography (micro-CT), histology, and immunohistochemistry staining analyses were performed.ResultsFlow cytometry results showed that rBMSCs were partially differentiated into iECs with a 35.1% conversion rate in terms of CD31. There were still 20.97% rBMSCs expressing CD90. Scanning electron microscopy (SEM) results indicated that cells from the wrapped cell sheet on the β-TCP scaffold apparently migrated into the pores of the β-TCP scaffold. The histology and immunohistochemistry staining results from in vivo implantation indicated that the BP/β-TCP and AP/β-TCP groups promoted the formation of blood vessels and new bone tissues in the bone defects more than the other two control groups. In addition, micro-CT showed that more new bone tissue formed in the BP/β-TCP and AP/β-TCP groups than the other groups.ConclusionsInducing rBMSCs to iECs could be a good strategy to obtain an endothelial cell source for prevascularization. Our findings indicate that the biomimetic periosteum with porous β-TCP scaffold has a similar ability to promote osteogenesis and angiogenesis in vivo compared to the autologous periosteum. This function could result from the double layers of biomimetic periosteum. The prevascularized cell sheet served a mimetic fibrous layer and the osteogenic cell sheet served a cambium layer of native periosteum. The biomimetic periosteum with a porous ceramic scaffold provides a new promising method for bone healing.

Morpho-histological analysis of tomato (Solanum lycopersicum L.) plants after treatment with juglone

Juglone is a substance that limits plant growth and has a toxic effect on plant development. In this study, we analyzed the influence of juglone at two different concentrations (10<sup>−3</sup> M and 10<sup>−4</sup> M), which were applied to different parts of <em>Solanum lycopersicum</em> L. plants (root system, stem after decapitation, and surface of a younger leaf or after autografting) for a short period of time (7 days), on the morphology and histology of stems. At a lower concentration, juglone had positive effects on plant growth, which resulted in an increase in interfascicular cambial cell divisions, faster development of a continuous cambium layer along the stem circumference, and development of fibers. Additionally, under the influence of juglone, the number of developing leaves increased and adventitious roots developed. The results are discussed based on the current literature concerning the reaction of plants to juglone and to stress conditions.

The histology of minigrafting of Persian walnut trees cv. chandler

Compared to other techniques of propagation, grafting is the most successful and feasible technique for asexual propagation of walnut plants. There is little information about graft union formation in walnut. Therefore, the objective of this study was to evaluate histological events during graft union formation in Juglans regia L. cv. Chandler scions when minigrafted on the one-year-old seedlings. Cross and longitudinal sections of the graft union were taken for examining different stages of grafting process after 1, 14, 30, 60, 120, 180, 420 and 540 days of minigrafting. One day after grafting, brown necrotic layers were observed at the cut edges. The first callus cells were initiated from cambium layer of rootstock 14 days after grafting but there was weak connection between two parts. New vascular connections between rootstock and scion were observed 30 days after grafting . Vascular connections were increased in central parts of the graft union 60 days after grafting. In mid-summer (180 days after grafting), necrotic layer was almost disappeared in the central longitudinal sections but they were increased especially in the bark, callus and top parts of the graft union due to high temperature and low humidity. In 420 days after grafting, two parts were strongly connected by xylem vessels, but necrotic layer was still remained and observed in some parts. In 540 day after grafting which was coincided with the end of second growing season, two parts were tightly connected to each other and necrotic layer disappeared in most of cross and longitudinal sections.

Controlling Honey Locust (Gleditsia triacanthos) with Cut Stump- and Basal Bark-Applied Herbicides for Grazed Pasture

Honey locust is a deciduous tree that is now present throughout most of the United States. Fire suppression and introduction of honey locust into shelter belts has allowed honey locust to increase in pastures of mixed grass prairie. Because locust trees can produce abundant sprouts, mechanical measures also require herbicides to effectively control trees. Each year for 2 yr, trees were treated with one of five combinations of herbicides and application methods. Treatment combinations, on a v/v basis, included (1) triclopyr 25% + diesel 75% and (2) aminopyralid 5% + bark oil 95%, both applied to the lower 38 cm of basal bark including the root collar area of live trees, as well as (3) triclopyr 25% + diesel 75%, (4) aminopyralid 10% + water 90%, and (5) dicamba 33% + 2,4-D 2% + water 65%, all applied immediately to the outer cambium layer of cut stump surfaces. One year after treatment, aminopyralid applied as a basal bark or as a cut-tump treatment had the best control and averaged over 97% dead trees. The triclopyr + diesel cut-stump treatment had the fewest dead trees (just over 50%) and produced many new sprouts. In grazed pasture, treating cut tree surfaces with dicamba + 2,4-D + water or aminopyralid + water and treating standing live trees with a basal bark application of aminopyralid + oil are three effective control options. Triclopyr + diesel displayed better control on live standing trees with a basal bark treatment rather than as a cut-stump treatment.

Live Tissue Imaging to Elucidate Mechanical Modulation of Stem Cell Niche Quiescence.

The periosteum, a composite cellular connective tissue, bounds all nonarticular bone surfaces. Like Velcro, collagenous Sharpey's fibers anchor the periosteum in a prestressed state to the underlying bone. The periosteum provides a niche for mesenchymal stem cells. Periosteal lifting, as well as injury, causes cells residing in the periosteum (PDCs) to change from an immobile, quiescent state to a mobile, active state. The physical cues that activate PDCs to home to and heal injured areas remain a conundrum. An understanding of these cues is key to unlocking periosteum's remarkable regenerative power. We hypothesized that changes in periosteum's baseline stress state modulate the quiescence of its stem cell niche. We report, for the first time, a three‐dimensional, high‐resolution live tissue imaging protocol to observe and characterize ovine PDCs and their niche before and after release of the tissue's endogenous prestress. Loss of prestress results in abrupt shrinkage of the periosteal tissue. At the microscopic scale, loss of prestress results in significantly increased crimping of collagen of periosteum's fibrous layer and a threefold increase in the number of rounded nuclei in the cambium layer. Given the body of published data describing the relationships between stem cell and nucleus shape, structure and function, these observations are consistent with a role for mechanics in the modulation of periosteal niche quiescence. The quantitative characterization of periosteum as a stem cell niche represents a critical step for clinical translation of the periosteum and periosteum substitute‐based implants for tissue defect healing. Stem Cells Translational Medicine 2017;6:285–292

Використання діелектричних показників для визначення життєвого стану дерев в’яза шорсткого

Встановлено, що важливими критеріями відбору здорових, не уражених голландською хворобою (Graphium ulmi Schwarz) особин в'яза, поряд з морфологічними ознаками, є діелектричні показники – імпеданс і поляризаційна ємність. Між категоріями життєвого стану дерев в'яза та діелектричними показниками виявлено тісний кореляційний зв'язок (r2=0,88-0,98). Із погіршенням життєвого стану дерев в’яза величина поляризаційної ємності знижується, а величина імпедансу зростає. Загалом потрібний комплексний підхід до визначення життєвого стану дерев в'яза, який грунтується на використанні як морфологічних, так і діелектричних показників.

Periosteal PTHrP Regulates Cortical Bone Remodeling During Fracture Healing

Parathyroid hormone-related protein (PTHrP) is widely expressed in the fibrous outer layer of the periosteum (PO), and the PTH/PTHrP type I receptor (PTHR1) is expressed in the inner PO cambial layer. The cambial layer gives rise to the PO osteoblasts (OBs) and osteoclasts (OCs) that model/remodel the cortical bone surface during development as well as during fracture healing. PTHrP has been implicated in the regulation of PO modeling during development, but nothing is known as regards a role of PTHrP in this location during fracture healing.We propose that PTHrP in the fibrous layer of the PO may be a key regulatory factor in remodeling bone formation during fracture repair. We first assessed whether PTHrP expression in the fibrous PO is associated with PO osteoblast induction in the subjacent cambial PO using a tibial fracture model in PTHrP-lacZ mice. Our results revealed that both PTHrP expression and osteoblast induction in PO were induced 3days post-fracture. We then investigated a potential functional role of PO PTHrP during fracture repair by performing tibial fracture surgery in 10-week-old CD1 control and PTHrP conditional knockout (PTHrP cKO) mice that lack PO PTHrP. We found that callus size and formation as well as woven bone mineralization in PTHrP cKO mice were impaired compared to that in CD1 mice. Concordant with these findings, functional enzyme staining revealed impaired OB formation and OC activity in the cKO mice.We conclude that deleting PO PTHrP impairs cartilaginous callus formation, maturation and ossification as well as remodeling during fracture healing. These data are the initial genetic evidence suggesting that PO PTHrP may induce osteoblastic activity and regulate fracture healing on the cortical bone surface.

Bone transplantation and tissue engineering. Part II: bone graft and osteogenesis in the seventeenth, eighteenth and nineteenth centuries (Duhamel, Haller, Ollier and MacEwen).

In the 18th century, the fate of allografts and their role in bone formation became of interest to many orthopaedic surgeons. A controversy over the science of osteogenesis, the formation of bone, had emerged following the opposing views of Duhamel and von Haller. Duhamel noted that the periosteum had a deep osteogenic layer, which he termed the "cambium layer". However, von Haller claimed the opposite: the periosteum was not osteogenic. In the 19th century, Ollier performed comprehensive studies on the periosteum. Ollier's experiments were published in two volumes entitled "Traite Experimental et clinique de la regeneration des os" in 1867. His conclusion was that transplanted periosteum and bone survived and could become osteogenic under proper conditions. The controversy was furthered by MacEwen who believed, contrary to Duhamel and Ollier, that the periosteum had no osteogenetic power and was purely a limiting membrane giving direction to bone growth but taking no active part in it. This manuscript describes this period of controversies about the osteogenesis of the transplanted bone, marrow and periosteum that would eventually die or not and be replaced by surrounding tissue or be active for osteogenesis. Whether bone grafts are a form of passive scaffolding or active in osteogenesis was the main question about auto and allografts in the 18th and 19th centuries. In response to this challenge, many papers were written to defend each side of the argument.

Periosteum: characteristic imaging findings with emphasis on radiologic-pathologic comparisons.

The periosteum covers most bone structures. It has an outer fibrous layer and an inner cambial layer that exhibits osteogenic activity. The periosteum is a dynamic structure that plays a major role in bone modeling and remodeling under normal conditions. In several disorders such as infections, benign and malignant tumors, and systemic diseases, the osteogenic potential of the periosteum is stimulated and new bone is produced. The newly formed bone added onto the surface of the cortex adopts various configurations depending on the modalities and pace of bone production. Our aim here is to describe the anatomy, histology, and physiology of the periosteum and to review the various patterns of periosteal reaction with emphasis on relations between radiological and histopathological findings. A careful evaluation of the periosteal reaction and appearance of the underlying cortex, in combination with the MRI, clinical, and laboratory data, provides valuable information on lesion duration and aggressiveness, thereby assisting in the etiological diagnosis and optimizing patient management. A solid reaction strongly suggests a benign and slow-growing process that gives the bone enough time to wall off the lesion. Single lamellar reactions occur in acute and usually benign diseases. Multilamellar reactions are associated with intermediate aggressiveness and a growth rate close to the limit of the walling-off capabilities of the bone. Spiculated, interrupted, and complex combined reactions carry the worst prognosis, as they occur in the most aggressive and fast-growing diseases: the periosteum attempts to create new bone but is overwhelmed and may be breached.

Effect of preservation of corticoperiosteal attachment on bone healing at osteotomy sites after ulna-shortening osteotomy.

Although precise ulna-shortening osteotomy is popular, the procedure sometimes results in delayed union or nonunion. The periosteum including the inner cambium layer plays an important role in fracture healing. We tested the hypothesis that preservation of the corticoperiosteal attachment may accelerate healing at osteotomy sites after ulna-shortening osteotomy. We performed a chart review of 32 patients who underwent ulna-shortening osteotomy for ulnar impaction syndrome or triangular fibrocartilage complex tears in a retrospective single-surgeon series. Of the 32 cases, the periosteum was preserved in 21 osteotomies performed from April 2009 onwards (periosteum-preserved group) and not preserved in 11 osteotomies performed before April 2009 (control group). Following sugar tong immobilization, patients in both groups used a short wrist supporter during the first two postoperative weeks (POW) and up to at least four POW. Union of the osteotomy site was assessed at 2-week intervals using radiographs taken at three different projections until 12 POW and at 4-week intervals thereafter until 24 POW. Ulna shortening was performed using a transverse osteotomy cut with the aid of a commercially available compression device. All osteotomies achieved complete union except in one case in the control group. The mean interval to complete cortical union was 7.7weeks in the periosteum-preserved group and 9.5weeks in the control group. The corresponding mean times for endosteal union were 15.6 and 21.8weeks. The periosteum-preserved group had reduced times for both types of union but only the endosteal union time was significantly different from the control group. Preservation of the corticoperiosteal attachment significantly shortened the endosteal union time. Our results indicate that preservation of the periosteum may accelerate bone healing after ulna-shortening osteotomy.

Engineering vascularized bone grafts by integrating a biomimetic periosteum and β-TCP scaffold.

Treatment of large bone defects using synthetic scaffolds remain a challenge mainly due to insufficient vascularization. This study is to engineer a vascularized bone graft by integrating a vascularized biomimetic cell-sheet-engineered periosteum (CSEP) and a biodegradable macroporous beta-tricalcium phosphate (β-TCP) scaffold. We first cultured human mesenchymal stem cells (hMSCs) to form cell sheet and human umbilical vascular endothelial cells (HUVECs) were then seeded on the undifferentiated hMSCs sheet to form vascularized cell sheet for mimicking the fibrous layer of native periosteum. A mineralized hMSCs sheet was cultured to mimic the cambium layer of native periosteum. This mineralized hMSCs sheet was first wrapped onto a cylindrical β-TCP scaffold followed by wrapping the vascularized HUVEC/hMSC sheet, thus generating a biomimetic CSEP on the β-TCP scaffold. A nonperiosteum structural cell sheets-covered β-TCP and plain β-TCP were used as controls. In vitro studies indicate that the undifferentiated hMSCs sheet facilitated HUVECs to form rich capillary-like networks. In vivo studies indicate that the biomimetic CSEP enhanced angiogenesis and functional anastomosis between the in vitro preformed human capillary networks and the mouse host vasculature. MicroCT analysis and osteocalcin staining show that the biomimetic CSEP/β-TCP graft formed more bone matrix compared to the other groups. These results suggest that the CSEP that mimics the cellular components and spatial configuration of periosteum plays a critical role in vascularization and osteogenesis. Our studies suggest that a biomimetic periosteum-covered β-TCP graft is a promising approach for bone regeneration.

Effects of Wheeled Cable Skidding on Residual Trees in Selective Logging in Caspian Forests

There are increasing demands on silvicultural practices to reduce the adverse impacts of harvesting. Damage to residual trees caused by ground-based skidding was assessed in stands with low [3.4 stems per hectare (sph), 14.36 m3/ha], medium (5.2 sph, 21.61 m3/ha), and high (7.1 sph, 25.95 m3/ha) harvest intensities. Skidding was conducted using a cable skidder. After the skidding operation, a field survey was conducted to collect data on all residual trees (species, dbh, height) and on tree wounds (size class, location, intensity of damage). It was hypothesized that increased harvest intensity leads to increased injury rates. The treatment with the highest harvest intensity was found to cause the highest percentage of damage and the largest stem wounds. The most common types of damage were stem wounds to the cambium layer and bark scrapes. In all three harvest intensity treatments the probability of individual tree damage decreased as skid-trail cross slope decreased and distance to skid-trail edge increased. It is concluded that harvesting intensity should be limited to 5 trees/ha during each harvesting operation to reduce extent of tree damage and thus future financial loss.