Human Immunodeficiency Virus Envelope Protein Gp120 Induces Proliferation but Not Apoptosis in Osteoblasts at Physiologic Concentrations

Patients with HIV infection have decreased numbers of osteoblasts, decreased bone mineral density and increased risk of fracture compared to uninfected patients; however, the molecular mechanisms behind these associations remain unclear. We questioned whether Gp120, a component of the envelope protein of HIV capable of inducing apoptosis in many cell types, is able to induce cell death in bone-forming osteoblasts. We show that treatment of immortalized osteoblast-like cells and primary human osteoblasts with exogenous Gp120 in vitro at physiologic concentrations does not result in apoptosis. Instead, in the osteoblast-like U2OS cell line, cells expressing CXCR4, a receptor for Gp120, had increased proliferation when treated with Gp120 compared to control (P<0.05), which was inhibited by pretreatment with a CXCR4 inhibitor and a G-protein inhibitor. This suggests that Gp120 is not an inducer of apoptosis in human osteoblasts and likely does not directly contribute to osteoporosis in infected patients by this mechanism

Swimming in a Sea of Shame: Incorporating Emotions into Explanations of Institutional Reproduction and Change

We theorize the role in institutional processes of what we call the shame nexus, a set of shame-related constructs: felt shame, systemic shame, sense of shame, and episodic shaming. As a discrete emotion, felt shame signals to a person that a social bond is at risk and catalyzes a fundamental motivation to preserve valued bonds. We conceptualize systemic shame as a form of disciplinary power, animated by persons’ sense of shame, a mechanism of ongoing intersubjective surveillance and self-regulation. We theorize how the duo of the sense of shame and systemic shame drives the self-regulation that underpins persons’ conformity to institutional prescriptions and institutional reproduction. We conceptualize episodic shaming as a form of juridical power used by institutional guardians to elicit renewed conformity and reassert institutional prescriptions. We also explain how episodic shaming may have unintended effects, including institutional disruption and recreation, when it triggers sensemaking among targets and observers that can lead to the reassessment of the appropriateness of institutional prescriptions or the value of social bonds. We link the shame nexus to three broad categories of institutional work

IL1-b and TNF-a differently modulate CXCL13 chemokine in stromal cells and osteoblasts isolated from Osteoarthritis patients: evidence of changes associated to cell maturation.

none8Autore/i del volume: -noneToneguzzi S.; Cristino S.; Grassi F.; Piacentini A.; Cavallo C.; Mariani E.; Facchini A.; Lisignoli G.Toneguzzi S.; Cristino S.; Grassi F.; Piacentini A.; Cavallo C.; Mariani E.; Facchini A.; Lisignoli G

Analysis of mesenchymal stem dimensional HYAFF 11 (R)-based cells grown on a prototype ligament scaffold

Ligaments are complex structures that maintain the mechanical stability of the joint. Healing of injured ligaments involves the interactions of different cell types, local cellular environment, and the use of devices. To gain new information on the complex interactions between mesenchymal stem cells (MSCs) and a specific hyaluronan-based prototype scaffold (HYAFF&REG;), useful for ligament tissue engineering, short time-course experiments were performed to analyze the proliferation, vitality, and phenotype of MSCs grown on the scaffold. MSC proliferation was analyzed using the MTT test, during the early time points (2, 4, 6, days). Viability was assessed using calcein/acetyloxymethylester immunofluorescence dye and confocal microscopy analysis. Hyaluronic acid receptor (CD44), typical matrix ligament proteins (collagen type I, type III, laminin, fibronectin, actin), and chondrogenic/osteogenic markers (collagen type 11 and bone sialoprotein) were evaluated by immunohistochemistry. Our data demonstrated that MSC growth and viability were cell density-dependent. MSCs completely wrapped the fibers of the scaffold, expressed CD44, collagen type I, type III, laminin, fibronectin, and actin, and were negative to collagen type II and bone sialoprotein. These data demonstrate that MSCs survive well in the hyaluronan-based prototype ligament scaffold, as assessed after 2 days from seeding, and express CD44, a receptor important for scaffold interaction, and proteins responsible for the functional characteristics of the ligaments. &COPY; 2005 Wiley Periodicals, Inc

Porous ceramics structured for bone-cartilage implants.

There are cases of damage to articular joints in which not only a reconstruction of the cartilage is necessary but also replacement of the underlying subchondral bone portion, the thickness of which can be as much as 1-2 mm. Are-construction of the articular surface must take into consideration the particular structure of the bone in the epiphysis position, characterised by an outward fine porosity. The structure of this external porosity does not allow cell migration from the inside to the outside of the bone surface although, at the same time, it does allow good permeation of physiological fluid, flowing out from the inside the bone. This physiological fluid transports oxygen, sugars, proteins and other molecules in order to supply nourishment to the cells (chondrocytes) which populate the layer of cartilage that overhangs the surface of the bone plate. Outgoing from the cartilage layer, the flux of physiological fluid sweeps away carbon dioxide and any other metabolic or catabolic products of the cells. The surface microporosity further serves to offer rootage to cartilaginous proteins for their natural mechanical retention in the site. Since a patent aimed at producing thin ceramic layers with a gradient of porosity (decreasing from one principal face to the opposite) has been applied for, these layers are going to be tested to evaluate the degree to which they meet the requirements. Preliminary tests carried out on samples at different but homogeneous porosity have emphasised that cell permeation of osteoblast cultures is practically stopped after some few tenths microns. The osteoblasts are shown to settle in the interior of the larger pores. They remodel the surrounding walls of the pores in which they lodge and start the production of bone nodules which are useful, for in vivo applications, in producing the desired tissue continuity between the interior of the ceramic and the underlying bone tissue, thus promoting a definitive firm setting. A cytological test, performed one week after cells had seeded on one side of the ceramic samples, has shown a provisional response towards the lodging material. In fact the cells assumed a globular shape (tending to flattening), but displaying cytoplasmatic processes of cellular interconnection. Measurements of the vitality, population and penetration into the cell pores inside the ceramic were carried out. On the basis of the results, the proposed ceramic devices with a gradient of porosity indicate their suitability for the intended function. Successive experimental steps will concern in vivo applications, simulating a repair intervention for an articular arthrosis