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The increase of proinflammatory cytokines in vaginal secretions may serve as a surrogate marker of unwanted inflammatory reaction to microbicide products topically applied for the prevention of sexually transmitted diseases, including HIV-1. Interleukin (IL)-l[beta] and IL-6 have been proposed as indicators of inflammation and increased risk of HIV-1 transmission; however, the lack of information regarding detection platforms optimal for vaginal fluids and interlaboratory variation limit their use for microbicide evaluation and other clinical applications. This study examines fluid matrix variants relevant to vaginal sampling techniques and proposes a model for interlaboratory comparisons across current cytokine detection technologies. II-1[beta] and IL-6 standards were measured by 12 laboratories in four countries, using 14 immunoassays and four detection platforms based on absorbance, chemiluminescence, electrochemiluminescence, and fluorescence. International reference preparations of cytokines with defined biological activity were spiked into (1) a defined medium simulating the composition of human vaginal fluid at pH 4.5 and 7.2, (2) physiologic salt solutions (phosphate-buffered saline and saline) commonly used for vaginal lavage sampling in clinical studies of cytokines, and (3) human blood serum. Assays were assessed for reproducibility, linearity, accuracy, and significantly detectable fold difference in cytokine level. Factors with significant impact on cytokine recovery were determined by Kruskal-Wallis analysis of variance with Dunn's multiple comparison test and multiple regression models. All assays showed acceptable intra-assay reproducibility; however, most were associated with significant interlaboratory variation. The smallest reliably detectable cytokine differences (P < 0.05) derived from pooled interlaboratory data varied from 1.5- to 26-fold depending on assay, cytokine, and matrix type. IL-6 but not IL-1[beta] determinations were lower in both saline and phosphate-buffered saline as compared to vaginal fluid matrix, with no significant effect of pH. The (electro)chemiluminescence-based assays were most discriminative and consistently detected < 2-fold differences within each matrix type. The Luminex-based assays were less discriminative with lower reproducibility between laboratories. These results suggest the need for uniform vaginal sampling techniques and a better understanding of immunoassay platform differences and cross-validation before the biological significance of cytokine variations can be validated in clinical trials. This investigation provides the first standardized analytic approach for assessing differences in mucosal cytokine levels and may improve strategies for monitoring immune responses at the vaginal mucosal interface.

Optimization of clinical heat treatments for various pathologies requires accurate numerical modeling of the heat transfer, evolution of thermal damage, and associated changes in the material properties of the tissues. This paper presents two phenomenological equations that quantify time-dependent thermal damage in a uniaxial collagenous tissue. Specifically, an empirical rule-of-mixtures model is shown to describe well heat-induced axial shrinkage (a measure of underlying denaturation) in chordae tendineae which results from a spectrum of thermomechanical loading histories. Likewise an exponential decay model is shown to describe well the partial recovery (e.g., renaturation) of chordae when it is returned to body temperature following heating. Together these models provide the first quantitative descriptors of the evolution of heat-induced damage and subsequent recovery in collagen. Such descriptors are fundamental to numerical analyses of many heat treatments because of the prevalence of collagen in many tissues and organs. Index Terms - Arrhenius, denaturation, kinetics, rate processes, shrinkage, thermal damage.

During normal embryogenesis, embryonic stem cells (ESCs) reside in the context of complex three-dimensional tissue structures, in particular of extracellular matrices (ECMs), which determine cell migration, proliferation, and differentiation. Therefore, to study ESC differentiation in an in vivo-like microenvironment, three-dimensional culture systems are necessary. Here, we developed protocols for ESC cultures in three-dimensional systems consisting of collagen matrices (collagen gels and porous collagen sponges) to investigate the mechanisms of ESC differentiation as well as the formation of tissue-like structures. In collagen matrices, ESCs differentiate into neural, epithelial, and endothelial lineages. In this system, ESCs form various tissue-like structures. The abilities of ESCs to form such structures in two chemically similar but topologically different matrices are different. In particular, in collagen gels ESCs form gland-like circular structures, whereas in collagen sponges ESCs are scattered through the matrix and form aggregates. To mimic the in vivo situation further, we developed a protocol for co-cultures of ESCs with human dermal fibroblasts or keratinocytes in collagen matrixes. Co-culture with fibroblasts in collagen gel facilitates ESC differentiation into cells of a neural lineage expressing nestin, neural cell adhesion molecule (NCAM), and class III beta-tubulin. In collagen sponges, keratinocytes facilitated ESC differentiation into cells of an endothelial lineage expressing factor VIII. Thus, the developed protocols promote ESC differentiation into a particular lineage, accompanied by the formation of tissue-like structures. Three-dimensional culture systems are a valuable tool for directing ESC differentiation and the formation of organs and tissues.