Modeling of phosphate ion transfer to the surface of osteoblasts under normal gravity and simulated microgravity conditions.

We have modeled the transport and accumulation of phosphate ions at the remodeling site of a trabecular bone consisting of osteoclasts and osteoblasts situated adjacent to each other in straining flows. Two such flows are considered; one corresponds to shear levels representative of trabecular bone conditions at normal gravity, the other corresponds to shear level that is representative of microgravity conditions. The latter is evaluated indirectly using a simulated microgravity environment prevailing in a rotating wall vessel bioreactor (RWV) designed by NASA.

Bone cell survival in microgravity: evidence that modeled microgravity increases osteoblast sensitivity to apoptogens.

Studies were performed to evaluate the effects of modeled microgravity on the induction of osteoblast apoptosis. MC3T3-E1 osteoblast-like cells were cultured in alginate carriers in the NASA-approved high aspect ratio vessel (HARV). This system subjects the cells to a time-averaged gravitational field (vector-averaged gravity) to simulate low gravity conditions.

Frank Stinchfield Award. Titanium surface with biologic activity against infection.

Despite immense improvements, periprosthetic infection continues to compromise the result of otherwise successful joint arthroplasty. There are various limitations in the treatment of periprosthetic infection, the most important of which is the inability to deliver antibiotics to the local tissue without the need for intravenous administration. We have developed a novel route to covalently tether vancomycin to a metal (titanium) surface, which showed effective bactericidal activity because of a vancomycin coupling.

Differentiation of mesenchymal stem cells towards a nucleus pulposus-like phenotype in vitro: implications for cell-based transplantation therapy.

Objective: Because mesenchymal stem cells can differentiate into chondrocyte-like cells, we ask the question, can mesenchymal stem cells commit to the nucleus pulposus phenotype?

Background: Back pain, a significant source of morbidity in our society, is linked to degenerative changes of the intervertebral disc. Absence of suitable graft tissue limits therapeutic approaches for repair of disc tissue. For this reason, there is considerable interest in developing "tissue engineering" strategies for the regeneration of the nucleus pulposus.

Stem cell regeneration of the nucleus pulposus.

Low back pain due to disc degeneration is one of the largest health problems faced in this nation when judged by lost work time and direct as well as indirect costs. Many experimental methods are being explored to treat or to reverse the effect of disc degeneration. This article reviews the strategy of a tissue engineering approach to disc regeneration.

Apoptosis and survival of osteoblast-like cells are regulated by surface attachment.

We tested the hypothesis that RGDS peptides regulate osteoblast survival in culture. Osteoblast-like MC3T3-E1 cells were allowed to attach to RGDS peptides that had been tethered to a silicone surface utilizing a previously described grafting technique. The RGDS-modified surface caused up-regulation of alpha(v)beta(3) integrin.

Fibronectin adsorption on surface-activated poly(dimethylsiloxane) and its effect on cellular function.

This article reports that surface modification of poly(dimethylsiloxane) (PDMS) influences fibronectin (Fn) adsorption and enhances cell attachment. Controlled adsorption of Fn on chemically activated polymer substrates is known to influence cellular function. Thin films of PDMS were spun cast on silicon wafers to obtain homogeneous and molecularly smooth surfaces.

Decellularized vein as a potential scaffold for vascular tissue engineering.

Purpose: Current strategies to create small-diameter vascular grafts involve seeding biocompatible, compliant scaffolds with autologous vascular cells. Our purpose was to study the composition and strength of decellularized vein to determine its potential as a vascular tissue-engineering scaffold.

Methods: Intact human greater saphenous vein specimens were decellularized by using sodium dodecyl sulfate (SDS).

Model surfaces engineered with nanoscale roughness and RGD tripeptides promote osteoblast activity.

Cell adhesion to biomaterials is a prerequisite for tissue integration with the implant surface. Herein, we show that we can generate a model silica surface that contains a minimal-length arginine-glycine-aspartic acid (RGD) peptide that maintains its biological activity. In the first part of this study, attachment of MC3T3-E1 osteoblast-like cells was investigated on silicon oxide, amine terminated substrates [i.

Ionizing radiation sensitizes bone cells to apoptosis.

Osteoradionecrosis is a common sequelae of radiation therapy for head and neck cancer. To test the hypothesis that radiation induces osteoradionecrosis by induction of bone cell apoptosis, we exposed MC3T3-E1 osteoblast-like cells to gamma-radiation and evaluated cell viability. Twenty-four hours postirradiation, measurement of osteoblast dehydrogenase activity suggested that there was a small decrease in cell viability.

An organ culture system for the study of the nucleus pulposus: description of the system and evaluation of the cells.

Study Design: The goal of this study was to develop a methodology to maintain intervertebral discs in organ culture, thereby preserving tissue architecture and metabolic function in a three-dimensional environment.

Methods: Using a microdissection technique, intervertebral discs were removed from rat lumbar vertebrae. The discs were maintained in organ culture, and cell viability was evaluated histochemically and using probes that measured mitochondrial function and thiol status.

Induction of apoptosis in skeletal tissues: phosphate-mediated chick chondrocyte apoptosis is calcium dependent.

In an earlier study, we have shown that Pi induced apoptosis of terminally differentiated hypertrophic chondrocytes. To ascertain whether Ca2+ modulates Pi-induced cell death, we asked the following two questions: First, can we prevent Pi-induced apoptosis by removing Ca2+ from the culture medium; alternatively, can we potentiate cell death by increasing the Ca2+ concentration? Second, can we inhibit chondrocyte apoptosis by blocking Pi transport? We also explored the mechanism of apoptosis by evaluating mitochondrial activity and reactive oxygen species (ROS) generation in cells treated with the ion pair. We noted that EDTA and EGTA blocked Pi-induced apoptosis in a dose-dependent manner.

[The training programs for correction of the nutritional disturbances behavior in patients with arterial hypertension and diabetes mellitus type 2].

The aim of the present study is to evaluate the alimentary disorders in patients with high risk for cardiovascular diseases, also in patients with arterial hypertension (AH) and njn--insulin-diabetes mellitus (DM). The results showed that patients with AH (155 patients) and DM (107 patients) have high prevalence of the alimentary disorders: high consumption of total fat--46% (DM) and 70.9% (AH), high consumption of carbohydrates--14.

Mechanisms by which extracellular matrix components induce osteoblast apoptosis.

Bone cell apoptosis is seen at sites of active turnover. We hypothesize that at these sites, factors released from resorbing bone induce apoptosis of vicinal cells. Related to this observation, earlier studies indicate that an elevation in the level of inorganic phosphate ions combined with a modest increase in the calcium (Ca2+) concentration, or a rise in the local concentration of RGD-containing peptides promote osteoblast apoptosis.

Detection of apoptotic gene expression in human osteoblast-like cells by cDNA microarrays.

Global gene expression during the induction of ion pair-mediated apoptosis was evaluated by an apoptosis microarray system. Human bone marrow stromal cells were cultured in the presence of 10(-6) M dexamethasone to promote osteogenesis. After 28 days, these cells expressed elevated alkaline phosphatase activity and maintained Cbfa1 expression even when challenged with an apoptogen.

Ring-shaped vortex domain in type-II superconductors.

We present results of experiments in superconducting niobium and numerical simulations showing the creation of a metastable ring-shaped vortex domain by heating. Such vortex rings, if pinned by structural defects, can exist forever.

Intervertebral disc tissue engineering II: cultures of nucleus pulposus cells.

The main objective of the current investigation was to regenerate cells of the nucleus pulposus without loss of phenotype. Nucleus pulposus cells were isolated from intervertebral discs from adult rabbits, grown in monolayer culture, and then maintained as a micromass pellet in tube culture. The specimens were evaluated by transmission and light microscopy, reverse transcriptase polymerase chain reaction, and immunohistochemistry.

Intervertebral disc tissue engineering I: characterization of the nucleus pulposus.

The characteristics of the nucleus pulposus cells from adult rabbits maintained in in vitro cultures were described in another study. Herein, the authors provide a parallel profile of adult rabbit nucleus pulposus in situ, therefore allowing direct comparisons between in vitro and in situ investigations. Nucleus pulposus specimens from adult rabbits were evaluated using biochemical and immunohistochemical morphologic techniques.

Maturation-dependent thiol loss increases chondrocyte susceptibility to apoptosis.

The major aim of the current investigation was to evaluate the role of thiols during chondrocyte maturation and apoptosis. Using a thiol-sensitive fluorescent probe, we found that in chick growth plate chondrocytes, hypertrophy is accompanied by a decrease in the glutathione content. In this study, we show that the maturation-dependent loss of thiol, although not causing death of maturing chondrocytes, drastically increases susceptibility to apoptosis by oxidative and nitrosoactive stress.

Diagnosis of pregnancy-associated uterine venous plexus thrombosis on the basis of transvaginal sonography.

Objective: To describe the sonographic signs of uterine venous plexus thrombosis.

Methods: Four pregnant patients had a diagnosis of uterine venous plexus thrombosis in the first half of gestation. The diagnosis was based on transvaginal sonography only in 3 cases, and the fourth had magnetic resonance imaging corroboration.

The fate of the terminally differentiated chondrocyte: evidence for microenvironmental regulation of chondrocyte apoptosis.

Chondrocytes contained within the epiphyseal growth plate promote rapid bone growth. To achieve growth, cells activate a maturation program that results in an increase in chondrocyte number and volume and elaboration of a mineralized matrix; subsequently, the matrix is resorbed and the terminally differentiated cells are deleted from the bone. The major objective of this review is to examine the fate of the epiphyseal chondrocytes in the growing bone.

RGD peptides immobilized on a mechanically deformable surface promote osteoblast differentiation.

The major objective of this work was to attach bone cells to a deformable surface for the effective transmission of force. We functionalized a silastic membrane and treated it with 3-aminopropyltriethoxysilane (APTS). A minimal RGD peptide was then covalently linked to the aminated surface.

A signaling pathway leading to metastasis is controlled by N-cadherin and the FGF receptor.

The intracellular signaling events causing tumor cells to become metastatic are not well understood. N-cadherin and FGF-2 synergistically increase migration, invasion, and secretion of extracellular proteases in breast tumor cells. Here, we define a metastatic signaling cascade activated by N-cadherin and FGF-2.

A homoleptic phosphine adduct of Tl(I).

A homoleptic phosphine adduct of thallium(I) supported by a tris(phosphino)borate ligand has been isolated and structurally characterized.