IUPS Physiology Education Workshop series in India: organizational mechanics, outcomes, and lessons.

Active learning promotes the capacity of problem solving and decision making among learners. Teachers who apply instructional processes toward active participation of learners help their students develop higher order thinking skills. Due to the recent paradigm shift toward adopting competency-based curricula in the education of healthcare professionals in India, there is an emergent need for physiology instructors to be trained in active-learning methodologies and to acquire abilities to promote these curriculum changes. To address these issues, a series of International Union of Physiological Sciences (IUPS) workshops on physiology education techniques in four apex centers in India was organized in November 2018 and November 2019. The "hands-on" workshops presented the methodologies of case-based learning, problem-based learning, and flipped classroom; the participants were teachers of basic sciences and human and veterinary medicine. The workshop series facilitated capacity building and creation of a national network of physiology instructors interested in promoting active-learning techniques. The workshops were followed by a brainstorming meeting held to assess the outcomes. The aim of this report is to provide a model for implementing a coordinated series of workshops to support national curriculum change and to identify the organizational elements essential for conducting an effective Physiology Education workshop. The essential elements include a highly motivated core organizing team, constant dialogue between core organizing and local organizing committees, a sufficient time frame for planning and execution of the event, and opportunities to engage students at host institutions in workshop activities.

Ott's protein osmotic pressure of serum and interstitial fluid in chickens (Gallus gallus): effect of age and gender.

Protein, or colloid, osmotic pressure (COP) is of sufficient magnitude to exert a powerful effect on Starling forces across the capillary wall. Although avian skin lacks active mechanisms for fluid transmission, such as sweating, it is now hypothesized that passive oncotic forces may regulate fluid flow and distribution in the skin and related phenomena. In this study, serum protein profiles, as well as COP in serum (COP(s)) and in suction blister fluid (COP(sbf)), were determined in juvenile, young and adult female and male chickens. For assessing COP, the Ott-Ahlqvist equation was applied. This equation can formulate the effects of multiple serum proteins on COP, according to their molecular mass. The COP values determined in chickens were lower than those previously found in mammals. COP(s) increased with age in males, and was higher in adult males than in adult females. In contrast, COP(sbf) decreased with age in females, although it was better preserved in adult males. The age-dependent decrease in COP was associated with a parallel decrease in the concentration of α(1)-globulin and albumin, and a positive correlation between packed cell volume (PCV) and COP was found. It is concluded that ageing affects Ott's COP around the vessel wall, and that an oncotic mechanism preserves plasma volume. The preservation of COP(sbf) in males suggests better maintenance of the interstitial ground substance. Females seem to lose more of a tissue's COP(s) counteracting force than males, probably as a result of gender-specific changes in the composition of the interstitial matrix. Further studies are required to elucidate the structure and function of avian lymphatics and their role in skin rheology.

Is there life in the horny layer? Dihydropyridine and ryanodine receptors in the skin of female and male chickens (Gallus domesticus).

Previous findings in pigeons and chickens show that Ca(2+) may be accumulated inside the cornified skin cells and that Ca(2+) microenvironments with a lower- or higher-than-blood concentration may exist in the skin. It has been suggested that the skin may function as a secretory pathway or a reservoir for Ca(2+) recycling. To test this hypothesis, we studied the dermis and epidermis of female and male chickens in vivo to find out whether cellular mechanisms exist for the accumulation, recycling or secretion of Ca(2+). For calcium influx and intracellular Ca(2+) release, respectively, the density of dihydropyridine receptors (DHPRs) and ryanodine receptors (RyRs) was examined, using high-affinity (-)-enantiomers of dihydropyridine and ryanodine labelled with fluorophores. To investigate Ca(2+) utilization in the skin, the systemic and local activity of the enzyme alkaline phosphatase (ALP) and the concentration of ionic Ca(2+) were measured in plasma and in cutaneous extracellular fluid, collected by suction blister technique. We found that both DHPRs and RyRs were present in all skin layers from dermis to horny layer. However, receptor densities were highest in the surface layers. With a basic calcium-rich diet, receptor densities were higher in males, particularly in the dermis and mid-epidermis. After a reduction in the nutritional Ca(2+) input, receptor densities in males decreased to the same level as in females, in which the receptor densities were not affected by the amount of Ca(2+) in the diet or that resulting from coming out of lay. The extracellular concentration of ionic Ca(2+) per se was not found to affect the density of DHPRs and RyRs in the skin. Spatially, RyRs seem to be located in the periphery of the sebokeratinocyte. ALP activity was shown to be lower in the extracellular fluid than in the plasma in both sexes. However, activity in both extracellular domains increased significantly in females that had come out of lay. This was probably connected with the increased osteoblast activity related to the reformation of structural bone. In conclusion, voltage-sensitive L-type Ca(2+) channels for ion influx and RyRs for Ca(2+) release are present in the cells of the skin of female and male chickens. Higher densities in the males receiving excessive Ca(2+) imply an increased capacity for Ca(2+) influx and intracellular processing. Even though the functional interactions between DHPRs and RyRs in the sebokeratinocytes could not be demonstrated, peripheral colocation and high receptor densities at the level of exocytosis of the lamellar bodies point to their role as part of a signalling pathway for secretion. The finding that DHPRs and RyRs are present in the horny layer implies that the function of the outermost skin might be more active than had been previously thought and that this function might be both secretory and sensory.

Novel function of the skin in calcium metabolism in female and male chickens (Gallus domesticus).

To study the role of the skin in differential calcium metabolism in White Leghorn chickens, we compared the composition of suction blister fluid (SBF) collected from cutaneous blisters with blood and serum in female and male animals in various physiological states. As an estimate for interstitial fluid (IF), SBF was used as a determinant of local cutaneous metabolism. Sample collection was carried out under ketamine-xylazine anesthesia. Eight chickens of both sexes were raised freely in similar environmental conditions and fed with similar food during their growth from juvenile to sexually mature and fully adult state. SBF, blood and serum were examined for concentrations of ionized Ca2+, Na+ and K+ with ion-selective electrodes (ISEs), and osmolalities by freezing point osmometry. pH and total protein content were also assessed. Our results showed that SBF of chickens is calcium-poor at the juvenile state and that it draws more Ca2+ in adult males than laying females of the same age. Interestingly, Ca2+ accumulation was observed also in females after laying had ceased. There was a positive correlation between blood and SBF Ca2+ in females but a negative one in males. In general, it was found that SBF of chickens was rich in Na+ and K+, was hypertonic compared to serum at the juvenile state and had a protein content of 36-47% of that in serum. Different from mammals, SBF in adult chickens was alkaline with the mean values of 8.7+/-0.14 in females and 8.8+/-0.06 in males. Age- and sex-related variability in cutaneous Ca2+ concentrations in chickens, and the differences of SBF composition between that of mammals point to a novel role of skin functions in avians. Possible functions of the skin as a dynamic calcium source balancing the free circulating Ca2+ levels and, also, as an excretory organ for Ca2+ are discussed.

Local action of exogenous nitric oxide (NO) on the skin blood flow of rock pigeons (Columba livia) is affected by acclimation and skin site.

We studied the blood flow over dorsal and abdominal, non-brooding patch skin of two groups of pigeons: one group was thermally acclimated to cold (winter-acclimatized, WAC) while the other group was acclimated to a mesic environment (thermally non-challenged, NOC). Two bilateral patches at the measurement sites were treated simultaneously with a gel containing sodium nitrate and ascorbic acid, to generate nitric oxide (NO), and a vehicle gel. Blood flow was measured by laser Doppler velocimetry. Changes induced by these treatments were calculated against basic blood flow values for the corresponding patch. The results showed that the basic blood flow over the abdominal skin patches at room temperature was higher than over the dorsal skin in both acclimation states, but comparison revealed a sustainably higher level of basic skin blood flow in the WAC pigeons. The local response to exogenous NO was non-uniform over the two skin areas measured, and a specific vasodilatory action on the abdominal microvessels was recorded in the NOC pigeons. Abdominal vasodilatation in the WAC pigeons seemed to involve other mechanisms as well as local NO-dependent ones, among which the role of cold-induced vasodilatation (CIVD) is discussed here. Interestingly, the dorsal skin seemed to be less responsive to the action of NO, irrespective of the acclimation state. Our results show that acclimation state and skin site affect the action of exogenous NO on local skin blood flow, and we suggest that the differences reflect acclimation-induced changes in the vascularity of the skin and in its sensitivity to thermal stimuli and that the roles of the abdominal and dorsal skin are different with respect to environmental changes.