Steady state temperature distribution in dermal regions of an irregular tapered shaped human limb with variable eccentricity

The investigators in the past have developed some models of temperature distribution in the human limb assuming it as a regular circular or elliptical tapered cylinder. But in reality the limb is not of regular tapered cylindrical shape. The radius and eccentricity are not same throughout the limb. In view of above a model of temperature distribution in the irregular tapered elliptical shaped human limb is proposed for a three dimensional steady state case in this paper. The limb is assumed to be composed of multiple cylindrical substructures with variable radius and eccentricity. The mathematical model incorporates the effect of blood mass flow rate, metabolic activity and thermal conductivity. The outer surface is exposed to the environment and appropriate boundary conditions have been framed. The finite element method has been employed to obtain the solution. The temperature profiles have been computed in the dermal layers of a human limb and used to study the effect of shape, microstructure and biophysical parameters on temperature distribution in human limbs. The proposed model is one of the most realistic model as compared to conventional models as this can be effectively employed to every regular and nonregular structures of the body with variable radius and eccentricity to study the thermal behaviour.     

Ingestion of coffee polyphenols suppresses deterioration of skin barrier function after barrier disruption,concomitant with the modulation of autonomic nervous system activity in healthy subjects

The aim of this study was to evaluate the effect of consumption of coffee polyphenols (CPPs) on the autonomic nervous system activity and decreased skin barrier function caused by sodium dodecyl sulfate (SDS) treatment. In this single-blind, placebo-controlled study, ten healthy male subjects consumed either a beverage containing CPPs or a placebo beverage for four weeks. CPPs significantly suppressed the deterioration in skin barrier function and skin moisture content induced by SDS treatment after the third week. Furthermore, in the heart rate variability analysis, CPPs significantly produced an increase in parasympathetic nervous activity, and a decrease in sympathetic nervous activity after the four weeks of beverage consumption. These results suggest that CPPs might influence the regulation of the autonomic nervous system and contribute to the suppressive effect on deterioration of skin barrier function.     

Kinesio taping influences the mechanical behaviour of the skin of the low back: A possible pathway for functionally relevant effects

Despite claims of functional benefits of kinesio tape application, little mechanistic evidence exists to support physiological pathways to achieve these benefits. As kinesio tape is adhered directly to the skin, it can be supposed that any pathway needs to first achieve effects at this level. To address this, two layers of the skin, the combined epidermis and dermis, as well as the hypodermis were studied. Specifically, -kinematic measures of skin surface stretch and retraction, as well as ultrasound measures of skin thickness, were made along all edges of kinesio tape applied over the low back. Results demonstrated that the more superficial skin layer (combined epidermis and dermis), but not the deeper hypodermis, was significantly stretched (p = .0001) and thinner (p = .0016) at either end of the tape, and significantly retracted (p < .0001) and thicker (p = .0001) along the lateral edges of the tape. These results were partly dependent upon spine posture; skin retraction along the tape edges was only apparent in neutral and flexed (but not extended) spine postures, while skin thinning at the tape ends was only apparent in neutral and extended (but not flexed) spine postures. Hypodermal thickness was not affected by kinesio tape application at any location or in any posture. In summary, measured deformations at the skin surface and within the epidermal and dermal regions provide plausible pathways through which kinesio tape could achieve its claimed benefits.     

A bioreactor system for interfacial culture and physiological perfusion of vascularized tissue equivalents

A pivotal requirement for the generation of vascularized tissue equivalents is the development of culture systems that provide a physiological perfusion of the vasculature and tissue-specific culture conditions. Here, we present a bioreactor system that is suitable to culture vascularized tissue equivalents covered with culture media and at the air–medium interface, which is a vital stimulus for skin tissue. For the perfusion of the vascular system a new method was integrated into the bioreactor system that creates a physiological pulsatile medium flow between 80 and 120 mmHg to the arterial inflow of the equivalent's vascular system. Human dermal microvascular endothelial cells (hDMECs) were injected into the vascular system of a biological vascularized scaffold based on a decellularized porcine jejunal segment and cultured in the bioreactor system for 14 days. Histological analysis and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) staining revealed that the hDMECs were able to recolonize the perfused vascular structures and expressed endothelial cell specific markers such as platelet endothelial cell adhesion molecule and von Willebrand factor. These results indicate that our bioreactor system can serve as a platform technology to generate advanced bioartificial tissues with a functional vasculature for future clinical applications.     

Skin color in the squids Loligo pealii and Loligo opalescens

Summary Rapid, physiological color changes seen in the skin of cephalopods are due to a unique anatomical system composed of chromatophore organs and iridophores. The morphology and ultrastructure of the chromatophores was studied in the squids Loligo pealii Lesueur and Loligo opalescens Berry. A three-dimensional model of a brown chromatophore was reconstructed from serial sections for the electron microscope.The chromatophore organ is composed of a central nucleated pigment cell, 10–30 obliquely striated muscle cells (radially arranged on the equator of the pigment cell), axons, Schwann cells, and sheath cells. The pigment cell consists of a central aggregation of pigment granules and surrounding peripheral cytoplasmic compartments. These regions are incompletely separated by an electron-dense, sac-like structure, the pigment container. Proximal portions of a muscle cell contact the pigment cell in regions called myo-chromatophore junctions. Neuromuscular and myo-muscular junctions are also present.The results presented are discussed in terms of previous morphological and physiological studies of chromatophores.Part of a study submitted in partial fulfillment of the requirement for the degree of Ph. D. (Anatomy), the Graduate School of Basic Medical Sciences, New York Medical College, New York, N.Y. 10029.The research reported here was in part supported by grants from the Health Research Council of the City of New York (U-1008) and United States Public Health Service, General Research Grant No. FR-05398.Report on some of this material was given at the Annual Meeting of the American Association of Anatomists, Philadelphia, Pennsylvania, April 19–22, 1971.     

Geographic distribution of human skin colour: A selective compromise between natural selection and sexual selection?

Modern humans have been shaped by the cumulative action of natural selection, non-adaptive random change, and sexual selection. The last of these is not universal and has prevailed in one of two circumstances: (1) A surplus of females due to high male mortality, combined with ecological constraints on female participation in food procurement which discourage males from taking second wives; (2) A surplus of single males due to generalized polygyny with relatively low male mortality. These circumstances are most likely to occur in (1) Arctic tundra environments, specifically the vast expanse of tundra covering most of Europe up to 10,000 B.P., and in (2) regions dominated by generalized polygyny, notably sub-Saharan Africa. Sexual selection often acts on existing sex differences, including perhaps sexual dimorphism in human skin colour. Whereas women are universally fairer in complexion, men are browner and ruddier; parallel to this, most human societies see lighter skin as more feminine and darker skin as more masculine. Hence, sexual selection should favour lighter pigmented women when a surplus of single females must compete for a mate. Since skin colour is only mildly sex-linked, both sexes would lighten in pigmentation within the population in question. Similarly, when a surplus of single males must compete for a mate, both sexes would darken. Geographic variation in human skin colour may thus represent a selective compromise between two counterbalancing forces: natural selection, as determined by latitudinal variation in sunlight; and sexual selection, as determined by variations in the following: male mortality rates, incidence of polygyny, and ecological constraints on female participation in food procurement.     

Immunohistochemical detection of p53 protein in basal cell skin cancer after microwave-assisted antigen retrieval

p53 is the most frequently altered tumor-suppressor gene in skin cancer. In normal tissues the p53 protein (wild type) has a very short half-life and it is not detectable immunohistochemically. In contrast, the mutant p53 protein has an extended half-life in tumor cells and can be detected by immunohistochemical methods. p53 is widely used as an indicator of tumor aggression and progression. Fixation methods especially formaldehyde based fixation may mask the immunohistochemical detection of p53 protein but antigen retrieval methods enhance the inmmunohistochemical detection of p53 protein by remodification of protein structure. This study was designed to evaluate the efficacy of different fixatives, of microwaving and microwave pretreatment method to retrieve p53 immunoreactivity in paraffin-embedded non-lesioned (adjacent normal tissue) human skin samples or pathological human skin samples diagnosed as basal cell carcinoma. The samples were fixed at RT and/or in microwave oven either in neutral buffered formalin or alcohol for different time periods. For antigen retrieval, the sections were irradiated in a microwave oven for 5 cycles in 10 mM citrate buffer (pH 6.00). In this study the effects of six different fixation methods on the immunohistochemical staining have been investigated in basal cell tumor specimens. The application of antigen retrieval method was also examined and compared. Optimal results were obtained using samples fixed in alcohol either at room temperature (24 h) or in microwave oven.     

Circadian aspects of body temperature regulation in exercise

Internal and external factors contribute to resting core temperature and affect thermoregulation. Also, a robust circadian rhythm exists, implying that the body is in “heat-gain” or “heat-loss” modes at different times during the 24 h. Moreover, many variables associated with exercise, and the body's capacity for exercise, show circadian variation. All these factors contribute to circadian changes in thermoregulation during exercise. Attention is focused on responses at the onset of exercise, “critical temperature”, and recovery after exercise. Practical implications of circadian changes in thermoregulation during exercise include ergogenic aids and inter-individual differences, including those due to gender, age and acclimatisation.     

YAC tripeptide of epidermal growth factor promotes the proliferation of HaCaT keratinocytes through activation of EGFR

Epidermal growth factor (EGF) is known to play key roles in skin regeneration and wound-healing. Here, we demonstrate that Pep2-YAC, a tripeptide covering residues 29-31 in the B loop of EGF, promotes the proliferation of HaCaT keratinocytes with activity comparable to EGF. The treatment of HaCaT cells with Pep2-YAC induced phosphorylation, internalization, and degradation of EGFR and organization of signaling complexes, which consist of Grb2, Gab1, SHP2, and PI3K. In addition, it sti mulated the phosphorylation of ERK1/2 at Thr 202/Tyr 204 and of Akt1 at Ser 473 and the nuclear translocation of EGFR, STAT3, c-Jun, and c-Fos. These results suggest that Pep2-YAC may be useful as a therapeutic agent for skin regeneration and wound-healing as an EGFR agonist. [BMB Reports 2014; 47(10): 581-586]