Serum bone markers in patients with loosening of cemented total hip endoprosthesis]

Serum levels of bone markers N-mid osteocalcin (OCN-Mid) and Cross-Laps in 20 patients (8 men and 12 women) with loosening of at least one element of total hip endoprosthesis confirmed during operation were compared with age and sex matched group with OA. Marker levels were measured by direct chemoluminescency using Modular E-170. Statistical analysis were done with t-Student test (alpha = 0.05). There were no significant differences in OCN-Mid, Cross-Laps levels and OCN-Mid/Cross-Laps ratio between both groups. Implant loosening is a slow process taking place on a relatively small surface in comparison to whole skeleton, so bone markers have no clinical value in diagnostics of total hip loosening.     

Integration and differentiation of human embryonic stem cells transplanted to the chick embryo.

Human embryonic stem (ES) cells are pluripotent cells that can differentiate into a large array of cell types and, thus, hold promise for advancing our understanding of human embryology and for contributing to transplantation medicine. In this study, differentiation of human ES cells was examined in vivo by in ovo transplantation to organogenesis-stage embryos. Colonies of human ES cells were grafted into or in place of epithelial-stage somites of chick embryos of 1.5 to 2 days of development. The grafted human ES cells survived in the chick host and were identified by vital staining with carboxyfluorescein diacetate or use of a green fluorescent protein-expressing cells. Histologic analysis showed that human ES cells are easily distinguished from host cells by their larger, more intensely staining nuclei. Some grafted cells differentiated en masse into epithelia, whereas others migrated and mingled with host tissues, including the dorsal root ganglion. Colonies grafted directly adjacent to the host neural tube produced primarily structures with the morphology and molecular characteristics of neural rosettes. These structures contain differentiated neurons as shown by beta-3-tubulin and neurofilament expression in axons and cell bodies. Axons derived from the grafted cells penetrate the host nervous system, and host axons enter the structures derived from the graft. Our results show that human ES cells transplanted in ovo survive, divide, differentiate, and integrate with host tissues and that the host embryonic environment may modulate their differentiation. The chick embryo, therefore, may serve as an accessible and unique experimental system for the study of in vivo development of human ES cells.     

Orthopaedics on the Internet]

The Internet is becoming a more integral part of daily education for all orthopaedic surgeons. Author presents web sites, which are interesting resources of orthopaedic knowledge.     

Electrophysiological Characterization of a Novel Conotoxin That Blocks Molluscan Sodium Channels

A novel peptide toxin, PnIVB, isolated from the venom of Conus pennaceus blocks voltage-gated sodium current in Aplysia neurons. Complete blockade is obtained at a PnIVB concentration of 80±2.2 nM and 50% blockade at 16±0.86 nM. The potency of PnIVB in blocking Aplysia sodium current is four orders of magnitude larger than that of tetrodotoxin. The toxin has no paralytic activity when injected into fish. The rapid blockade of sodium current by PnIVB is not associated with a change in the activation or inactivation kinetics of the current, or with the reversal potential. Sodium current blockade is reversible after a 30 min wash with 50 times the bath volume. The novel conotoxin PnlVB can be used as a powerful tool for mollusc neurobiological research and as a molecular probe to explore the structure-function relations of voltage-gated sodium channel subtypes.     

Concerning the differentiability of the energy function in vector quantization algorithms.

The adaptation rule of Vector Quantization algorithms, and consequently the convergence of the generated sequence, depends on the existence and properties of a function called the energy function, defined on a topological manifold. Our aim is to investigate the conditions of existence of such a function for a class of algorithms including the well-known 'K-means' and 'Self-Organizing Map' algorithms. The results presented here extend several previous studies and show that the energy function is not always a potential but at least the uniform limit of a series of potential functions which we call a pseudo-potential. It also shows that a large number of existing vector quantization algorithms developed by the Artificial Neural Networks community fall into this class. The framework we define opens the way to studying the convergence of all the corresponding adaptation rules at once, and a theorem gives promising insights in that direction.     

Advanced systemic sclerosis complicated by pulmonary hypertension and complete atrioventricular block: a case report.

BACKGROUND: Systemic sclerosis (SSc) is a connective tissue disorder of unknown etiology characterized by fibrosis of the skin and visceral organs, in which the heart is frequently (40-70% of patients) and severely involved. Pulmonary hypertension affects 10-15% of patients with SSc and is one of the most important complications adversely influencing their survival. CASE REPORT: The case report presents a 59-year-old male patient with advanced systemic sclerosis whose initial examination revealed pulmonary hypertension, rhythm and atrioventricular conduction disturbances, and elevated level of NT-proBNP. After six months the patient deteriorated; an increase in NT-proBNP level and progression of pulmonary hypertension were observed. CONCLUSIONS: The described case is followed by a discussion of cardiovascular involvement in systemic sclerosis and emphasizes that heart involvement in SSc may have very serious clinical implications.     

Treatment results of aseptic non-unions of long bones with medullary canal reaming followed by intramedullary nailing]

This paper presents results of treatment of 46 consecutive patients with pseudoarthroses of the long bones treated with closed intramedullary reaming followed by intramedullary nailing. There were 22 nonunions of the tibia, 15 of the femur, 3 of the humerus and 6 of the forearm. The union occurred in 40 cases, among them in 3 of 4 treated atrophic, that gives 87% success. None of treated pseudoarthrosis of the humerus united.     

The clinical significance of sinus membrane perforation during augmentation of the maxillary sinus.

PURPOSE: Augmentation of the maxillary sinus floor is a well-documented technique and is generally accepted as a pure implantology procedure to facilitate placement of dental implants in the posterior atrophic maxilla. The objective of this report was to evaluate the significance of the sinus membrane perforations on the incidence, complications, and success rate of this procedure. PATIENTS AND METHODS: Patients who received sinus floor augmentation and simultaneous placement of dental implant were included in this study. Subgroup I consisted of patients who had their sinus membrane perforated and repaired during the procedure with resorbable membrane. Subgroup II consisted of patients whose Schneiderian membrane was not perforated during the procedure. The patients were followed between 1 to 4 years after augmentation. RESULTS: All perforations were classified as class II or III. The success rate of the implants in the perforation group was 94.4%, and that for the nonperforation group was 93.9%. The difference between the 2 study groups was statistically not significant. A significant statistical correlation was found between the residual ridge height and the membrane perforation (P < .01). CONCLUSIONS: Mainly due to technical difficulties, maxillary sinus membrane perforation occurs more frequently with a small height of residual alveolar bone. In this study, no statistical difference was observed in the success rate of the immediate implants placed with sinus bone grafting in patients whose membrane was perforated versus those patients in whom an intact membrane was maintained.