A new tool to test active ingredient using lactic acid in vitro,a help to understand cellular mechanism involved in stinging test: An example using a bacterial polysaccharide (Fucogel®)

The stinging test is an in vivo protocol that evaluates sensitive skin using lactic acid (LA). A soothing sensation of cosmetics or ingredients can be also appreciated through a decrease in stinging score. To predict the soothing sensation of a product before in vivo testing, we developed a model based on an LA test and substance P (SP) release using a co‐culture of human keratinocytes and NGF‐differentiated PC12 cells. A bacterial fucose‐rich polysaccharide present in Fucogel^® was evaluated as the soothing molecule in the in vivo stinging test and our in vitro model. Excluding toxic concentrations, the release of SP was significant from 0.2% of lactic acid for the PC12 cells and from 0.1% of lactic acid for the keratinocytes. When the pH was adjusted to approximately 7.4, LA did not provoke SP release. At these concentrations of LA, 0.1% of polysaccharide showed a significant decrease in SP release from the two cellular types and in co‐cultures without modifying the pH of the medium. In vivo, a stinging test using the polysaccharide showed a 30% decrease in prickling intensity vs the placebo in 19 women between the ages of 21 and 69. Our in vitro model is ethically interesting and is adapted for cosmetic ingredients screening because it does not use animal experimentation and limits human volunteers. Moreover, Fucogel^® reduced prickling sensation as revealed by the in vivo stinging test and inhibits the neurogenic inflammation as showed by our new in vitro stinging test based on SP release.     

Factors associated with early and late failure of dental implants

Osseointegration is a good indication of the clinical success of titanium implants referring to the direct anchorage of such implants to the surrounding host bone. Despite the high success rate of endosseous dental implants, they do fail. A lack of primary stability, surgical trauma, and infection seem to be the most important causes of early implant failure. Early signs of infection may be an indication of a much more critical result than if the same complications occur later, because of disturbance of the primary bone healing process. Occlusal overload and periimplantitis seem to be the most important factors associated with late failure. Suboptimal implant design and improper prosthetic constructions are among those risk factors responsible for implant complications and failure. This concise review highlights the main causes associated with early and late implant failure, as thorough knowledge of this unavoidable clinical fact is essential in the field of oral implantology.     

Influence of an acute increase in systemic vascular resistance on transpulmonary thermodilution-derived parameters in critically ill patients

Objective The transpulmonary thermodilution technique enables measurement of cardiac index (CI), intrathoracic blood volume (ITBV), global end-diastolic volume (GEDV), and extravascular lung water (EVLW). In this study, we analyzed the robustness of this technique during an acute increase in systemic vascular resistance (SVR). Design Prospective, clinical study. Setting Surgical intensive care unit in a university hospital. Patients and methods Twenty-four mechanically ventilated septic shock patients, who for clinical indications underwent extended hemodynamic monitoring by transpulmonary thermodilution and continuously received norepinephrine. Interventions and main results After baseline measurements, mean arterial pressure was increased briefly by increasing norepinephrine dosage and hemodynamic measurements were repeated before a control measurement was obtained. At each time point, 15 cc of 0.9% saline (< 8 °C) was administered by central venous injection in triplicate. Fluid status and respirator adjustments were kept constant. ANOVA with an all-pairwise comparison method was used for statistical analysis. Heart rate, central venous pressure, and EVLW remained constant throughout, while SVR significantly changed from 551 ± 106 to 746 ± 91 dyn*s*cm⁻⁵ and again to 566 ± 138 dyn*s*cm⁻⁵ (p < 0.05). However, CI and central blood volumes showed a reversible significant increase, i.e., ITBV went from 816 ± 203 to 867 ± 195 ml/m² and then to 821 ± 205 ml/m² and GEDV from 703 ± 178 to 747 ± 175 ml/m² and finally to 704 ± 170 ml/m², respectively. In eight patients, 2-D echocardiography was applied and revealed a reversible increase in left-ventricular end-diastolic area. Conclusion An acute increase in SVR by increasing norepinephrine dosage results in a reversible increase in central blood volumes (ITBV, GEDV) as measured by transpulmonary thermodilution and supported by echocardiography. This work was presented in part at the 19th annual meeting of the European Society of Intensive Care Medicine, 24–27 September 2006, Barcelona. Samir Sakka has received fees from Pulsion Medical Systems AG, Munich, Germany, for giving lectures.