Characterization of a bovine collagen-hydroxyapatite composite scaffold for bone tissue engineering

Different biomaterials have been used as scaffolds for bone tissue engineering. Here we characterize a biomaterial composed of sintered (1100 degrees C) and powdered hydroxyapatite (HA) and type I collagen (Coll), both of bovine origin, designed for osteoconductive and osteoinductive scaffolds. Coll/HA proportions were 1/2.6 and 1/1 (wet weight), and particles sizes varied from 200 to 400 microm. Vv (volume density) and Sv (surface to volume density) for the HA particles in the composite ranged from 0.48 +/- 0.06 to 0.55 +/- 0.02 and 5.090 +/- 0.545 to 6.366 +/- 0.289 microm(-1), respectively. Due to the relatively small changes in Vv and Sv, a macroporosity could be characterized for the biocomposite. X-ray diffraction and infrared spectroscopy showed that the sintered bone was composed essentially of HA with minimum additional groups such as surface calcium hydroxide, surface and crystal water, free carbon dioxide and possibly brushite. Mass spectrometry detected carbonates at A and B sites of HA, and weakly bound to the structure. Human osteoblasts adhered and spread on both the HA particle surface and the collagen fibers, which seemed to guide cells between adjacent particles. The biocomposite studied has several characteristics considered as ideal for its use as a scaffold for osteoconduction and osteoinduction.     

T cell receptor γδ repertoire is skewed in cerebrospinal fluid of multiple sclerosis patients: molecular and functional analyses of antigen-reactive γδ clones

To study the relevance of γδ T cells in multiple sclerosis (MS) we analyzed the T cell receptor (TCR) γδ repertoire and the antigen reactivity of γδ clones isolated from cerebrospinal fluid (CSF). In T cell cultures derived from CSF we found an increased percentage of Vδ1⁺ cells as compared to peripheral blood of the same donors. Phenotypic analysis of cells from MS CSF with Vγ- and Vγ-specific monoclonal antibodies (mAb) showed that the Vγ1 chain is most frequently associated with γ chains belonging to the VγI family. Sequence analysis of TCR genes revealed heterogeneity of junctional regions in both δ and γ genes indicating polyclonal expansion. γδ clones were established and some recognized glioblastoma, astrocytoma or monocytic cell lines. Stimulation with these targets induced serine esterase release and lymphokine expression characteristic of the T_H0-like phenotype. Remarkably, these tumor-reactive γδ cells were not detected in the peripheral blood using PCR oligotyping, but were found in other CSF lines independently established from the same MS patient. Altogether, these results demonstrate that in the CSF there is a skewed TCR γδ repertoire and suggest that γδ cells reacting against brain-derived antigens might have been locally expanded.     

Experimental muscle pain changes motor control strategies in dynamic contractions

This study investigated the effect of muscle pain on muscle activation strategies during dynamic exercises. Ten healthy volunteers performed cyclic elbow flexion/extension movements at maximum speed for 2 min after injection of (1) hypertonic (painful) saline in the biceps brachii, (2) hypertonic saline in both biceps brachii and triceps brachii, and (3) isotonic (nonpainful) saline in the biceps brachii muscle. Surface electromyographic (EMG) signals were collected from the upper trapezius, biceps brachii, triceps brachii, and brachioradialis muscles (to estimate EMG amplitude) and with an electrode arrays from biceps brachii (to estimate muscle fiber conduction velocity [CV]). In all conditions, the acceleration of the movement decreased throughout the exercise, and kinematic parameters were not altered by pain. With respect to the control condition, pain induced a decrease of the biceps brachii (mean ± SE, –23±4%) and brachioradialis (–10±0.4%) integrated EMG (IEMG) in the beginning of the exercise, and an increase (45±3.5%) of the upper trapezius IEMG at all time points during the exercise. The biceps brachii IEMG decreased over time during the nonpainful exercises (–11±0.6%) while it remained constant in the painful condition. Biceps brachii CV decreased during painful conditions (–12.8±2.2%) while it remained constant during the nonpainful condition. In conclusion, muscle pain changes the motor control strategy to sustain the required dynamic task both in the relative contribution between synergistic muscles and in the motor unit activation within the painful muscle. Such a changed motor strategy may be highly relevant in models of occupational musculoskeletal pain conditions.     

A novel mutation of varicella-zoster virus associated to fatal hepatitis.

BACKGROUND: Lethal varicella in immunocompetent hosts is rare and its pathogenesis is largely unknown. The discovery of glycoprotein E (gE) mutants showing attributes consistent with increased virulence in vitro and in animal models, provided a possible molecular mechanism underlying a more aggressive virus infection. However, these mutants have never been associated with unusually severe clinical cases. OBJECTIVES: To varicella-zoster virus (VZV) mutations that correlate with increased virulence. RESULTS: We report a case of fatal hepatitis caused by a VZV bearing a novel mutation on the 3B3 monoclonal antibody epitope of gE in an immunocompetent host. CONCLUSIONS: This report describes a mutant VZV responsible for an aggressive clinical course in an immunocompetent host. Linking these severe clinical presentations of VZV infection to virus mutations might provide insights into the underlying pathogenic mechanisms.     

CD34+ Cord Blood Cell-Transplanted Rag2−/− γc−/− Mice as a Model for Epstein-Barr Virus Infection

Recent studies suggest that Epstein-Barr virus (EBV) can infect naïve B cells, driving them to differentiate into resting memory B cells via the germinal center reaction. This hypothesis has been inferred from parallels with the biology of normal B cells but has never been proven experimentally. Rag2^−/− γ_c^−/− mice that were transplanted with human CD34⁺ cord blood cells as newborns were recently shown to develop human B, T, and dendritic cells, constituting lymphoid organs in situ. Here we used this model to better define the strategy of EBV infection of human B cells in vivo and to compare this model system with different conditions of EBV infection in humans. Our results support the model of EBV persistence in vivo in cases that were characterized by follicular hyperplasia and a relatively normal CD4⁺ and CD8⁺ T-cell distribution. Intriguingly, in cases that were characterized by nodular and diffuse proliferation with a preponderance of CD8⁺ T cells, similar to infectious mononucleosis, EBV still infects naïve B cells but also induces clonal expansion and ongoing somatic mutations without germinal center reactions. Our results reveal different strategies of EBV infection in B cells that possibly result from variations in the host immune response. Future experiments might allow understanding of the mechanisms responsible for persistent EBV infection and provide targets for more highly tailored therapeutic interventions.     

Monte Carlo simulation of light fluence in tissue in a cylindrical diffusing fibre geometry

The propagation of light emitted by a linear light diffuser in a cylindrical hollow organ was investigated by means of the Monte Carlo (MC) method. The height and radius of the cavity, scattering (mu(s)) (or reduced scattering, mu'(s)) and absorption (mu(a)) coefficients, anisotropy (g), and refractive indices of the media involved (n1, n2) are required as input data by the MC code, as are characteristics of the light diffuser (length, delivered power and emission profile). Results of our MC model were tested by measuring the light fluence rate in a tissue-simulating phantom (mu(a) = 0.5 cm(-1), mu(s) = 23 cm(-1) and g = 0.75) irradiated at 633 nm with a cylindrical diffuser. Since geometric and optical parameters determine the behaviour of light propagation in tissue, MC simulations with different sets of input parameters were carried out to provide qualitative as well as quantitative data useful in planning photodynamic therapy. Data are reported on light penetration and fluence rate build-up at mu(a) and mu'(s) values ranging between 0.1 and 5 cm(-1) and 2.5 and 50 cm(-1), respectively. Furthermore, results suggest that a shift and spread could occur in the isofluence curves along the symmetry axis, which depend on the diameter of the treated lumen as well as on the emission profile of the light diffuser. Using our data it is possible to estimate how inaccuracy in knowledge of the optical coefficients can affect (i.e. usually by increasing) the light dose scheduled at a certain depth into tissue.     

Quantitative analysis of beta-adrenergic blocking agents by NMR spectroscopy

The quantitative analysis by (1)H NMR of labetalol, oxprenolol and four other beta-adrenergic blocking agents is described. The method depends on the integration of selected resonances of the analyte and an internal reference which do not overlap. Procedures for the extraction of the analyte from tablets are given and corrections due to the NMR features of excipients outlined in some cases. The NMR method is reasonably precise and rapid, and the assay results compare favourably with those obtained by a UV procedure.     

Epidemiology of adverse drug reactions in intensive care units. A multicentre prospective survey

Summary Clinically relevant events possibly attributable to drug exposure have been monitored prospectively over a period of six months in 27 general intensive care units. Fifty-four events attributed to drugs were reported in 51 patients during their stay in hospital, corresponding to an overall incidence of 1.35%. The behaviour of the physicians following attribution of the events to a prescribed drug is analyzed and discussed in detail with respect to its relationship to the quality and severity of the reaction, and the classes of drugs. Twenty-four of the 4537 monitored admissions during the six months were due to life-threatening emergencies linked to the administration of drugs (14) and radio-contrast media (10) (overall incidence 0.5%). While the clinical burden attributable to adverse drug reactions in Intensive Care Units appears to be relatively small, the analysis shows that there is ample room for a greater reduction in their incidence. Coordinators: Drs M. L. Farina and G. Tognoni, Istituto di Ricerche Farmacologiche Mario Negri, Milan; Dr F. Procaccio, Neurosurgical ICU, Ospedale Ca' Granda, Niguarda, Milan.Investigators: Drs G. Barusco, Rovigo; F. Bassi, Milan; L. Bianchetti, Torino; E. Carchietti, Udine; G. Chilloni, Reggio Emilia; G. Costantini, Savigliano (CN); P. Ferrero, Aosta; E. Geat, Trento; F. Gorgerino, Torino; A. Lusini, Empoli (FI); G. Mantovani, Ferrara; S. Marchi, Bologna; P. Marcovigi, Forli; G. Marraro, Merate (CO); F. Merlo, Vicenza; E. Pagni, Bagno a Ripoli (FI); R. Pellegrino, Cuneo; C. Peruselli, Milan; A. Piovesano, Pordenone; R. Rinaldo, Cremona; R. Ruggerini, Piacenza; S. Sammartino, Torino; A. Sartore, Cittadella (PD); A. Scaglioli, Carpi (MO); G. Scopa, Terni; G. Zeffiro, Treviso; P. Zuccoli, Parma