The Role of Biomarkers for Starting Antifungals in the Intensive Care Unit

Invasive candidiasis is associated with high mortality rates (35% to 60%), similar to the range reported for septic shock. The most common types include candidemia, frequently observed in immunocompromised patients, and noncandidemic systemic candidiasis, which constitutes the majority of cases in critically ill patients. However, they are difficult to prove and a definite diagnosis usually occurs late in the course of the disease, thus contributing to their bad prognosis. Early empirical treatment improves the prognosis and currently relies on the positive predictive value (PPV) of risk-assessment strategies (colonization index, Candida score, predictive rules) based on combinations of risk factors, but it may have also largely contributed to the overuse of antifungal agents in critically ill patients. In this context, non- culture-based diagnostic methods, including specific and nonspecific biomarkers, may significantly improve the diagnosis of invasive candidiasis. Candida DNA and mannan antigen/antimannan antibodies are of limited interest for the diagnosis of invasive candidiasis as they fail to identify noncandidemic systemic candidiasis, despite early positivity in candidemic patients. The utility of 1,3-beta-D-glucan (b-D-glucan), a panfungal cell wall antigen, has been demonstrated for the diagnosis of fungal infections in immunocompromised patients. Preliminary data suggest that it is also detectable early in critically ill patients developing noncandidemic systemic candidiasis. To take advantage of the high negative predictive value of risk-assessment strategies and the early increase in specific fungal biomarkers in high-risk patients, we propose a practical 2-step approach to improve the selection of patients susceptible to benefit from empirical antifungal treatment.

Peptide-decorated chitosan derivatives enhance fibroblast adhesion and proliferation in wound healing.

RGD peptide sequences are known to regulate cellular activities by interacting with α5β1, αvβ5 and αvβ3 integrin, which contributes to the wound healing process. In this study, RGDC peptide was immobilized onto chitosan derivative 1,6-diaminohexane-O-carboxymethyl-N,N,N-trimethyl chitosan (DAH-CMTMC) to display RGDC-promoting adhesion for enhanced wound healing. The efficiency of N-methylation, O-carboxymethylation and spacer grafting was quantitatively and qualitatively analyzed by (1)H NMR and FTIR, yielding 0.38 degree of substitution for N-methylation and >0.85 for O-carboxymethylation. The glass transition temperatures for chitosan derivatives were also studied. Peptide immobilization was achieved through sulfhydryl groups using sulfosuccinimidyl (4-iodoacetyl)amino-benzoate (sulfo-SIAB method). RGDC immobilized peptide onto DAH-CMTMC was found to be about 15.3μg/mg of chitosan derivative by amino acid analysis (AAA). The significant increase of human dermal fibroblast (HDF) viability in vitro over 7 days suggests that RGDC-functionalized chitosan may lead to enhanced wound healing (viability >140%). Moreover, bio-adhesion and proliferation assays confirmed that coatings of RGDC-functionalized chitosan derivatives exhibit in vitro wound healing properties by enhancing fibroblast proliferation and adhesion. These results showed that RGDC peptide-functionalized chitosan provides an optimal environment for fibroblast adhesion and proliferation.

Determination of Rod and Cone Influence to the Early and Late Dynamic of the Pupillary Light Response.

PURPOSE: This study aims to identify which aspects of the pupil light reflex are most influenced by rods and cones independently by analyzing pupil recordings from different mouse models of photoreceptor deficiency. METHODS: One-month-old wild type (WT), rodless (Rho-/-), coneless (Cnga3-/-), or photoreceptor less (Cnga3-/-; Rho-/- or Gnat1-/-) mice were subjected to brief red and blue light stimuli of increasing intensity. To describe the initial dynamic response to light, the maximal pupillary constriction amplitudes and the derivative curve of the first 3 seconds were determined. To estimate the postillumination phase, the constriction amplitude at 9.5 seconds after light termination was related to the maximal constriction amplitude. RESULTS: Rho-/- mice showed decreased constriction amplitude but more prolonged pupilloconstriction to all blue and red light stimuli compared to wild type mice. Cnga3-/- mice had constriction amplitudes similar to WT however following maximal constriction, the early and rapid dilation to low intensity blue light was decreased. To high intensity blue light, the Cnga3-/- mice demonstrated marked prolongation of the pupillary constriction. Cnga3-/-; Rho-/- mice had no pupil response to red light of low and medium intensity. CONCLUSIONS: From specific gene defective mouse models which selectively voided the rod or cone function, we determined that mouse rod photoreceptors are highly contributing to the pupil response to blue light stimuli but also to low and medium red stimuli. We also observed that cone cells mainly drive the partial rapid dilation of the initial response to low blue light stimuli. Thus photoreceptor dysfunction can be derived from chromatic pupillometry in mouse models.