Eggshells as natural calcium carbonate source in combination with hyaluronan as beneficial additives for bone graft materials, an in vitro study.

Introduction: In bone metabolism and the formation especially in bone substitution, calcium as basic module is of high importance. Different studies have shown that the use of eggshells as a bone substitute material is a promising and inexpensive alternative. In this in vitro study, the effects of eggshell granulate and calcium carbonate towards primary bovine osteoblasts were investigated.

In vitro inhibition of HUVECs by low dose methotrexate - insights into oral adverse events.

Background: With socio-economic changes, dentists and maxillofacial surgeons are more and more faced with medically compromised patients. Especially, the admission of antirheumatic drugs has increased remarkably. So dentists and maxillofacial surgeons should be aware of related adverse reactions that affect the craniofacial region.

Quantitative analysis of dynamic behavior of osteoblasts during in vitro formation of micro-mass cell cultures.

Improvements in bone tissue engineering require an understanding of cellular and tissue level behavior of osteoblast-like cells. Experiments indicate that in the absence of an anchoring material, intercellular adhesion may be based on signals that promote cell activity resulting in the formation of a spheroid cell-matrix. The aim of the present study is to investigate the formation of scaffold-free three-dimensional micro-mass cell spheroids in vitro, and to characterize quantitatively the cell movement.

An in vitro study of osteoblast vitality influenced by the vitamins C and E.

Vitamin C and vitamin E are known as important cellular antioxidants and are involved in several other non-antioxidant processes. Generally vitamin C and vitamin E are not synthesized by humans and therefore have to be applied by nutrition. The absence or deficiency of the vitamins can lead to several dysfunctions and even diseases (e.

Impact of testosterone on the expression of organic anion transporting polypeptides (OATP-1A2, OATP-2B1, OATP-3A1) in malignant and non-malignant human breast cells in vitro.

Objectives: Postmenopausal hormone therapy (HT) increases local estrogen formation in breast tissue. The enzymatic substrates depend on transmembrane anion transporting polypeptides (OATPs) to reach intracellular enzymes. The aim of this study was to investigate the effect of testosterone (T) on the expression of OATP-1A2, OATP-2B1, and OATP-3A1 in malignant (MCF-7, BT-474) and non-malignant (HBL-100) breast cells in vitro.

Expression of vascular endothelial growth factor on chondrocytes increases with osteoarthritis - an animal experimental investigation.

Objective: To evaluate the expression of VEGF by chondrocytes of hyaline cartilage during the course of osteoarthritis (OA).

Methods: In 12 white New Zealand rabbits the anterior cruciate ligament (ACL) was resected to create an anterior instability of the knee. In 12 control rabbits only a sham operation without resection of the ACL was done.

Influence of hepatocyte growth factor on autologous osteochondral transplants in an animal model.

Purpose: Several studies have investigated the influence of different growth factors on hyaline cartilage regeneration. In a rabbit model, hepatocyte growth factor (HGF) was proven to increase the amount of hyaline-like chondrocytes in a mixed fibro-cartilaginous regenerate of small defects. The aim of the current study was to evaluate whether intra-articular administration of HGF influences the ingrowth of osteochondral grafts in a sheep model.

Decrease in the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes in animals with osteoarthritis.

Background: To evaluate the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes from hyaline cartilage over the course of osteoarthritis (OA).

Methods: In 12 NZW rabbits, the anterior cruciate ligament (ACL) was resected to create anterior instability of the knee. In 12 control rabbits, only a sham operation, without resection of the ACL, was performed.

Effects of hormone therapy on estrogen synthesis from E1S in the mammary gland of postmenopausal women.

Objectives: To investigate the effect of hormone therapy (HT) on the expression of hormone receptors and the ex vivo estrogen biosynthesis in the breast.

Methods: Comparative studies were carried out in breast tissue from 28 postmenopausal women undergoing breast surgery due to breast cancer (BC). Glandular breast tissue at least 1cm distant from the tumor was analyzed.

Deer antler regeneration: cells, concepts, and controversies.

The periodic replacement of antlers is an exceptional regenerative process in mammals, which in general are unable to regenerate complete body appendages. Antler regeneration has traditionally been viewed as an epimorphic process closely resembling limb regeneration in urodele amphibians, and the terminology of the latter process has also been applied to antler regeneration. More recent studies, however, showed that, unlike urodele limb regeneration, antler regeneration does not involve cell dedifferentiation and the formation of a blastema from these dedifferentiated cells.

Mineralization at the interface of implants.

Osseointegration of implants is crucial for the long-term success of oral implants. Mineralization of the bone's extracellular matrix as the ultimate step of a mature bone formation is closely related to implant osseointegration. Osteogenesis at oral implants is a complex process, driven by cellular and acellular phenomena.

Image-based extracorporeal tissue engineering of individualized bone constructs.

Purpose: Computer-aided technologies have been recently employed for use in extracorporeal bone tissue engineering strategies. In this pilot animal experimental study, the intention was to test whether autologous osteoblast-like cells cultured in vitro on individualized scaffolds can be used to support bone regeneration in a clinical environment.

Materials And Methods: For this purpose, mandibular bone defects were surgically introduced into the mandibles of minipigs and the scaffold of the defect site was modeled by computer-aided design/computer-aided manufacturing technique.

Expression of the matrix receptor CD44v5 on chondrocytes changes with osteoarthritis: an experimental investigation in the rabbit.

Objective: To evaluate the expression of CD44v5 on chondrocytes of hyaline cartilage during the course of osteoarthritis (OA).

Methods: In 12 white New Zealand rabbits the anterior cruciate ligament (ACL) was resected to create an anterior instability of the knee. In 12 control rabbits only a sham operation without resection of the ACL was done.

Cellularity and apoptosis after radiofrequency-induced shrinkage of collagenous tissue: assessment of postoperative immobilization using an in vivo rabbit model.

Background: Electrothermally-assisted capsular shrinkage has been gaining increased acceptance in the treatment of shoulder instability. Its indication in ACL-deficient knees has been discussed recently.

Methods: We examined the influence of immobilization on cell homeostasis of healing collagenous tissue after radiofrequency energy was applied to the patellar tendon in 23 rabbits.

Increase in the expression of the transmembrane surface receptor CD44v6 on chondrocytes in animals with osteoarthritis.

Objective: To evaluate the expression of CD44v6 on chondrocytes from hyaline cartilage over the course of osteoarthritis (OA).

Methods: In 12 NZW rabbits, the anterior cruciate ligament (ACL) was resected to create anterior instability of the knee. In 12 control rabbits, only a sham operation, without resection of the ACL, was performed.

Neuronal regeneration after application of radiofrequency energy to collagenous tissue is affected by limb immobilization: an in vivo animal study.

Despite widespread use of radiofrequency (RF)-shrinkage, there have been no studies on the influence of RF-energy on neural elements of collagenous tissue. The purpose of this study was to examine the effect of RF-shrinkage on neural structures of capsuloligamentous tissue and the recovery of neural elements under different postoperative treatment protocols. One patellar tendon of 46 New-Zealand-White rabbits was shrunk.

Hyaline cartilage degenerates after autologous osteochondral transplantation.

Objectives: Autologous osteochondral grafting is a well-established clinical procedure to treat focal cartilage defects in patients, although basic research on this topic remains sparse. The aim of the current study was to evaluate (1) histological changes of transplanted hyaline cartilage of osteochondral grafts and (2) the tissue that connects the transplanted cartilage with the adjacent cartilage in a sheep model.

Method: Both knee joints of four sheep were opened surgically and osteochondral grafts were harvested and simultaneously transplanted to the contralateral femoral condyle.

Immobilisation after radiofrequency-induced shrinkage of tendon. A histological study in rabbits.

Despite widespread use of radiofrequency (RF) shrinkage, there have been no animal studies on the effects of post-operative immobilisation on the histological properties of the shrunken tissue. We have therefore examined the role of post-operative immobilisation after RF shrinkage with special emphasis on the histological properties of collagenous tissue. One patellar tendon of 66 New Zealand White rabbits was shrunk.

Bone tissue engineering by primary osteoblast-like cells in a monolayer system and 3-dimensional collagen gel.

Purpose: To engineer living bone tissue in vitro, bone cells must be multiplied and differentiated in cell culture. Osteoblasts are known to be the crucial cells responsible for the bone modeling process. Periosteal-derived osteoblasts were therefore cultured for up to 3 weeks in Petri dishes as well as in a 3-dimensional collagen gel.

Histological studies of bone formation during pedicle restoration and early antler regeneration in roe deer and fallow deer.

The purpose of the present study was to examine the process of bone formation in the regenerating cranial appendages of roe deer (Capreolus capreolus) and fallow deer (Dama dama) during the early postcasting period. After the antlers are cast, osteoclastic and osteoblastic activities lead to a smoothing of the pedicle's separation surface, a strengthening of the pedicle bone, and a partial restoration of the distal pedicle portion that was lost along with the cast antler. Initially, bone formation occurs by intramembranous ossification, but early during the regeneration process cartilage is formed at the tips of the cranial appendages, and is subsequently replaced by bone in a process of endochodral ossification.

Histochemical and ultrastructural studies of cartilage resorption and acid phosphatase activity during antler growth in fallow deer (Dama dama).

Cartilage resorption in forming primary fallow deer antlers was studied by histochemistry and electron microscopy. A high activity of tartrate-resistant acid phosphatase (TRAP), a histochemical marker of skeletal resorbing cells, was first detected in cells located in the mesenchymal tissue separating the columns of hypertrophic cartilage. No cartilage resorption was observed in this region.

Vitamin E reduces platelet adhesion to human endothelial cells in vitro.

Although it has been reported that vitamin E (alpha-tocopherol) can reduce platelet adhesiveness and aggregation in vivo, the mechanism is still unknown. Therefore, the aim of the present study was to determine whether incubations of platelet-rich plasma (PRP) with vitamin E influence platelet adhesion to cultured endothelial cells. To exclude blood plasma involvement, also washed platelets were pretreated with alpha-tocopherol.

Periosteally derived osteoblast-like cells differentiate into chondrocytes in suspension culture in agarose.

Pluripotent cells from the periosteal layer adjacent to cortical bone attain an osteoblast-like phenotype in culture when reaching confluence in monolayer. It is unknown whether such newly differentiated osteoblast-like cells preserve the chondrogenic potential characteristics for stem cells derived from the periosteum. Primary osteoprogenitor cells derived from bovine metacarpal periosteum were differentiated into alkaline phosphatase-positive osteoblast-like cells by an established monolayer culture protocol.

Oxidized low-density lipoprotein inhibits the binding of monoclonal antibody to platelet glycoprotein IIB-IIIA.

Previous studies have shown that oxidized low-density lipoprotein (LDL) induces platelet activation more effectively than native LDL. To achieve a better understanding of the mechanism underlying the activation of human platelets by oxidized LDL, the present study relates the effect of oxidized LDL to changes of binding characteristics for glycoprotein (GP) IIb-IIIa. Washed human platelets were treated by monoclonal antibody against GP IIb-IIIa, and the ligand-receptor complexes were revealed by immunocytochemical techniques on the ultrastructural level.

Vitamin E (alpha-tocopherol) does not inhibit platelet stimulation by oxidized low density lipoprotein in vitro.

Platelet-rich plasma were treated with increasing concentrations of vitamin E (alpha-tocopherol). Washed platelets were exposed to oxidized low density lipoprotein (LDL) and examined by aggregometry and electron microscopy. The treatment of washed platelets by oxidized LDL induced morphological signs of activation like pseudopodia formation and an increase in light transmission.