Bond strength of porcelain on cast vs. wrought titanium.

The bond strength of porcelain fused to cast and wrought titanium surfaces was calculated from fracture loads in a 4-point bending test. Two different porcelain were applied (O'Hara and Duceratin). The surface of Ti-cast specimens was treated in two different ways to produce variations in the impurity level before porcelain veneering. Microhardness measurements as well as scanning electron microscopy with EDX analysis were conducted. The results showed no significant difference in bond strength between the two porcelains. Nor was any difference in bond capacity found between thoroughly blasted castings and wrought titanium. Significantly lower bond strengths were observed for lightly blasted specimens and for specimens treated with Gold bonding agent. Impurities in the surface region of the castings were found to be due to contact with the investment during solidification. This indicates that a thin surface layer (50-100 microns) of the casting should be removed before firing of the porcelain.     

Self-consistent field-molecular orbital (SCF-MO) calculations and nuclear magnetic resonance measurements for fosfomycin and related compounds

In the present work, the mechanism of action of fosfomycin [(-)-(1R,2S)-(1,2-epoxypropyl)phosphonic acid] as an antibiotic agent is studied by "ab initio" quantum mechanical calculations and by 1H, 13C, and 31P NMR measurements. Attention is focused on the relative charge density and chemical shift of the C(2) atom of the epoxy ring, which seems to be closely related with the activity of this antibiotic. The theoretical results suggest that the sulfhydryl addition should be preceded by a necessary anchoring of the phosphonate moiety on a positive group of the receptor.     

Successful 18-h acellular extracorporeal perfusion and replantation of porcine limbs - Histology versus nerve stimulation

The current standard for composite tissue preservation is static cold storage (SCS) and is limited to 6 h until irreversible muscle damage occurs. Extracorporeal perfusion (ECP) is a promising technique for prolonged preservation, however, functional results have been scarcely researched. This article assessed neuromuscular function and compared results to histological alterations to predict muscle damage after ECP. Forelimbs of twelve Dutch landrace pigs were amputated and preserved by 4 h SCS at 4–6 °C (n = 6) or 18 h mid-thermic ECP with University of Wisconsin solution (n = 6). Limbs were replanted and observed for 12 h. Sham surgery was performed on contralateral forelimbs (n = 12). Histology analysis scored four subgroups representing different alterations (higher score equals more damage). Muscle contraction after median nerve stimulation was comparable between ECP, SCS, and sham limbs (P = 0.193). Histology scores were higher in ECP limbs compared to SCS limbs (4.8 vs. 1.5, P = 0.013). This was mainly based on more oedema in these limbs. In-vivo muscle contraction was well preserved after 18 h ECP compared to short SCS, although histology seemed inferior in this group. Histology, therefore, did not correlate to muscle function at 12 h after replantation. This leads to the question whether histology or neuromuscular function is the best predictor for transplant success.     

Measurement of Glass Transition Temperatures of Freeze-Concentrated Solutes by Differential Scanning Calorimetry

Thermal analysis of aqueous solutions in which the solute does not crystallize immediately upon freezing was carried out to define the effects of experimental parameters on thermograms in the glass transition region. The intensity of enthalpy relaxations in the glass transition region is related to both the rate of cooling and the rate of heating through the glass transition region—slow cooling or slow heating increases the extent of structural relaxation in the glassy state and increases the intensity of the endotherm. Plots of the logarithm of heating rate versus l /Tg are linear, and activation enthalpies for structural relaxation are in the range of 210–350 kJ/mol. For polymeric solutes, both the activation enthalpies for structural relaxation and the heat capacity change accompanying the glass transition increase with increasing molecular weight of the solute. Molecular weight dependence of the observed midpoint of the glass transition agrees with the Fox–Flory relationship. Results are compared and contrasted with glass transitions in solid polymers and with the glass transition of hyperquenched water. Practical implications for characterization of formulations intended for freeze-drying are discussed.     

Trypan blue exclusion assay by flow cytometry

Dye exclusion tests are used to determine the number of live and dead cells. These assays are based on the principle that intact plasma membranes in live cells exclude specific dyes, whereas dead cells do not. Although widely used, the trypan blue (TB) exclusion assay has limitations. The dye can be incorporated by live cells after a short exposure time, and personal reliability, related to the expertise of the analyst, can affect the results. We propose an alternative assay for evaluating cell viability that combines the TB exclusion test and the high sensitivity of the flow cytometry technique. Previous studies have demonstrated the ability of TB to emit fluorescence when complexed with proteins. According to our results, TB/bovine serum albumin and TB/cytoplasmic protein complexes emit fluorescence at 660 nm, which is detectable by flow cytometry using a 650-nm low-pass band filter. TB at 0.002% (w/v) was defined as the optimum concentration for distinguishing unstained living cells from fluorescent dead cells, and fluorescence emission was stable for 30 min after cell treatment. Although previous studies have shown that TB promotes green fluorescence quenching, TB at 0.002% did not interfere with green fluorescence in human live T-cells stained with anti-CD3/fluorescein isothiocyanate (FITC) monoclonal antibody. We observed a high correlation between the percentage of propidium iodide+CD3/FITC⁺ and TB+CD3/FITC⁺ cells, as well as similar double-stained cell profiles in flow cytometry dot-plot graphs. Taken together, the results indicate that a TB exclusion assay by flow cytometry can be employed as an alternative tool for quick and reliable cell viability analysis.     

Sédation inhalée en réanimation: que reste-t-il de l’AnaConDa™ ?

Sedation contributes to patient’s comfort and plays an essential role in the intensive care unit (ICU). Several clinical studies have reported the occasional use of volatile halogenated agents in the ICU; however, long-term use is possible in routine for the provision of a dedicated evaporator filter (AnaConDa? [ACD]). Because of their low cost and pharmacological characteristics with a rapid therapeutic effect, a high therapeutic index, a possible use regardless of age and underlying medical conditions, and a good knowledge of their adverse effects, halogenated agents could be considered like possible ideal anesthetic agents in the ICU. The objective of this technical note is to clarify the potential indications of ACD device and describe its operative principles and potential drawbacks.     

Plasma thérapeutique dans les hémorragies sévères

Recent changes in plasma transfusion practices for severe hemorrhage are largely related to the recognition of an early endogenous coagulopathy associated with traumatic injury. Observational and mostly retrospective data suggest improved survival rates with high-dose plasma therapy, up to a 1:1 ratio of fresh frozen plasma to packed red blood cells, but the quality of evidence is limited. Putting it into practice raises many issues (early identification of patients at risk of massive bleeding, extrapolation to non-trauma settings, alternative or adjunctive treatments, among others) that are discussed in this brief review.