No description available.

No description available.

Understanding the physiological and behavioural reasons that result in voluntary water intake and the volume subsequently consumed in both the work place and during and following an exercise setting can provide further information on water balance and the necessity and requirements of water intake. The first study (Chapter 3) aimed to assess hydration status in the adult population at the start and end of a working day and the amount of water from beverages that was consumed. Urine osmolality and urine specific gravity (USG) suggested a large proportion of subjects arrived (osmolality: 54%; USG: 53%) and left (osmolality: 35%; USG: 33%) work in a hypohydrated state, with variation between subjects in the same and different places of work. Reported water intake varied between groups with males consuming more than females. To further examine hydration status it was proposed to assess the use of capillary blood sampling as an alternative to more restrictive venous blood sampling (Chapter 4), however, despite tracking changes in blood parameters in a similar capacity, the inconsistencies of results suggested capillary blood sampling could not be used reliably. The remaining chapters in the thesis examined voluntary water intake. In Chapter 5 this was during and following exercise in the cold. Less water was consumed compared to exercise in a warm environment and there was an indication of a blunted thirst response in the cold. Following high intensity intermittent exercise, more water was voluntarily consumed during a one hour recovery period compared to when continuous exercise of the same average power output was performed (Chapter 6). Following exercise there was increased serum osmolality, serum sodium concentration, plasma vasopressin concentration and blood lactate concentration compared to baseline values. The relative contribution that decreasing blood lactate concentrations and water intake during the recovery period had on serum osmolality could not be determined, so the study in Chapter 7 was carried out. The time period during which voluntary water intake was allowed was manipulated during a recovery period following a period of high intensity intermittent exercise. Allowing water intake for the full hour, the final 30 minutes or not at all, resulted in similar decreases in serum osmolality throughout the duration of the recovery period. A combination of finishing the period of exercise allowing plasma volume restoration, reduction in blood lactate concentration, reduction in serum sodium concentration, a restoration of blood lactate concentration and water intake appeared to contribute to decreased serum osmolality. Sensations of thirst were the main stimulants of voluntary water intake (Chapters 3, 5, 6 and 7), however, following exercise, sensations of thirst resulted in water consumption despite the majority of subjects not losing enough water (>2% body mass loss) to require additional rehydration. In this thesis, it can be concluded that voluntary water intake differs between individuals, between work environments, during and following exercise in different environments and following different exercise intensities. Water intake is generally initiated by sensations of thirst arising from physiological and behavioural mechanisms even in the absence of significant hypohydration and will reduce once satiated.

Thalassia testudinum, a stenohaline seagrass species, and Ruppia maritima, a euryhaline submerged aquatic vegetation species, were subjected to the same seven salinity levels (0 - 60) in a controlled environment. The response variables examined were the occurrence of leaf discoloration, plant growth rates, photosynthetic characteristics of blade segments (Pmax, respiration, alpha, and Ik), and osmolality changes within the plant tissues. These response variables were measured at exposure times of one, seven, and 28 days. Greater than 75% leaf discoloration occurred in Thalassia testudinum blades placed in 0, and 60 psu, while Ruppia maritima blades only became severely discolored in 60 psu. Plant growth rates were highest in 40 psu for T. testudinum and 20 psu for R. maritima. Pmax for both species was somewhat affected by salinity changes, but the plants did not appear to be photosynthetically compromised in their "optimal" ranges over time. Salinity effects on photosynthesis were less pronounced in R. maritima than in T. testudinum, which would be expected when comparing a euryhaline species to a stenohaline species. Both intercellular and intracellular osmolality showed a pattern of increase or decrease as the treatment salinities were altered from ambient levels (30 psu for T. testudinum and 20 psu for R. maritima). After one day of exposure to a new treatment salinity, the intercellular osmolality had changed significantly from ambient value, with a second shift, occurring mostly in the salinity extremes, for both seagrass species. This second shift is most likely due to the fact that at the extremes, the plants are being compromised. Changes in these physical and physiological responses indicate that significant increases and decreases in ambient salinity levels are initially stressful for both species. Both seagrass species had an optimal salinity as well as a range of salinities in which the long-term physiological stresses did not cause tissue death. Thalassia testudinum had the fewest stress responses in 40 psu, with an optimal range of 20 - 40 psu. Ruppia maritima had the fewest stress responses in 20 psu (growth salinity) with an optimal range of 0 - 40 psu. In this study, neither species was able to survive for 28 days in 60 psu (at which point the plants had been out of their respective optimal salinities for at least 42 days).

<p>After drinking water, the fluid quickly leaves the stomach thereby creating a hypotonic luminal environment in the duodenum. This in turn constitutes a potential threat to the integrity of the duodenal epithelium. It therefore seems highly likely that luminal hypotonicity activates physiological mechanisms that aim to increase luminal osmolality. One such physiological mechanism may be to increase mucosal permeability thereby facilitating the transport of osmolytes into the lumen.</p><p>A draw-back of performing experiments in anesthetized animals is that surgery <i>per se</i> depresses gut functions, such as peristalsis, by mechanisms involving endogenous prostaglandins. In this thesis it is shown that inhibition of cyclooxygenase-2 (COX-2), in animals subjected to an abdominal operation, restore and/or improve duodenal functions such as motility, mucosal bicarbonate secretion, hypotonicity-induced increase in mucosal permeability and the osmolality-adjusting capability.</p><p>Experiments revealed that the stomach is resistant to hypotonic challenge while the jejunum is more sensitive to hypotonicity-induced increase in mucosal permeability than the duodenum. The hypotonicity-induced increase in duodenal mucosal permeability is not due to injury but possibly reflects physiological dilatation of paracellular shunts.</p><p>Luminal perfusion of the duodenum with an isotonic solution lacking Cl^- decreased bicarbonate secretion while the lack of luminal Na⁺ increased mucosal permeability. Stimulation of bicarbonate secretion by COX-2 inhibition is to a large extent dependent on luminal Cl^- while that induced by vasoactive intestinal peptide is not.</p><p>The hypotonicity-induced increase in mucosal permeability involves the release and action of serotonin (5-HT) on 5-HT₃ and 5-HT₄ receptors and stimulation of enteric nerves strongly implicating physiological regulation of this process.</p>

After drinking water, the fluid quickly leaves the stomach thereby creating a hypotonic luminal environment in the duodenum. This in turn constitutes a potential threat to the integrity of the duodenal epithelium. It therefore seems highly likely that luminal hypotonicity activates physiological mechanisms that aim to increase luminal osmolality. One such physiological mechanism may be to increase mucosal permeability thereby facilitating the transport of osmolytes into the lumen. A draw-back of performing experiments in anesthetized animals is that surgery per se depresses gut functions, such as peristalsis, by mechanisms involving endogenous prostaglandins. In this thesis it is shown that inhibition of cyclooxygenase-2 (COX-2), in animals subjected to an abdominal operation, restore and/or improve duodenal functions such as motility, mucosal bicarbonate secretion, hypotonicity-induced increase in mucosal permeability and the osmolality-adjusting capability. Experiments revealed that the stomach is resistant to hypotonic challenge while the jejunum is more sensitive to hypotonicity-induced increase in mucosal permeability than the duodenum. The hypotonicity-induced increase in duodenal mucosal permeability is not due to injury but possibly reflects physiological dilatation of paracellular shunts. Luminal perfusion of the duodenum with an isotonic solution lacking Cl- decreased bicarbonate secretion while the lack of luminal Na+ increased mucosal permeability. Stimulation of bicarbonate secretion by COX-2 inhibition is to a large extent dependent on luminal Cl- while that induced by vasoactive intestinal peptide is not. The hypotonicity-induced increase in mucosal permeability involves the release and action of serotonin (5-HT) on 5-HT3 and 5-HT4 receptors and stimulation of enteric nerves strongly implicating physiological regulation of this process.

The aim of this thesis was to determine any association between plasma oxytocin and vasopressin concentrations and renal water and sodium excretion during normal pregnancy. In addition to investigate changes in concentrations of estradiol, progesterone, oxytocin, cortisol, and glucose in the blood before and in the nearest hours after delivery and if treatment with oxytocin affected these concentrations and the fluid balance during the different stages of labour. Oxytocin, vasopressin, estradiol, progesterone, and cortisol were analysed in blood plasma or serum by radioimmunoassay or ELISA: serum glucose, and osmolality, and sodium in plasma and urine were  analysed by standard laboratory techniques. Fifty-seven women were studied during pregnancy and fifty-one during parturition and post partum. The low plasma vasopressin and increasing plasma oxytocin concentrations with unchanged water and sodium excretion indicate that oxytocin assists vasopressin in concentrating urine during pregnancy. Plasma vasopressin concentration continued to be low during parturition and post partum. Urine flow and concentration was unrelated to changes in plasma sodium concentration, indicating regulation of fluid balance during parturition was different to the non-gravid state. Women with weak myometrial contractions during parturition (slow progress of labour) reacted differently than women with normal parturition and a group of women with fast progress of labour. The group with slow labour had lower serum estradiol concentration in the latency phase and became hyponatremic. Pulsatile and continuous oxytocin infusions were both effective in the treatment of slow progress of labour. A lower amount of oxytocin was needed to affect delivery when given as pulsatile infusion. Serum cortisol and glucose concentrations were high during labour and cortisol level remained elevated after delivery and glucose concentration reached the highest levels (12 mmol/L) at the same time. Insulin resistance together with the long time of elevated cortisol concentration partly explained the high glucose concentration. In conclusion, fluid balance is not regulated according to the usual sensitive osmotic and volumetric influence on vasopressin release from the neurohypophysis during pregnancy and parturition. Parturition involves a change from one demanding condition, pregnancy, to another, lactation. Parturition and the hours directly after delivery are a turbulent period involving considerable stress.

La capacité des globules rouges à modifier leur forme en fonction de conditions externes spécifiques représente une propriété fondamentale permettant aux cellules de traverser des capillaires de diamètres plus petits que leur propre diamètre. L’ektacytométrie est une technique utilisée pour mesurer la déformabilité des globules rouges en exposant un échantillon très dilué de sang à des contraintes de cisaillement et en mesurant l’élongation resultante des globules par l'analyse de la figure de diffraction laser. Ce travail contribue à la conception et l’évaluation d’un nouveau dispositif de diagnostic basé sur la méthode microfluidique d'ektacytométrie à gradient osmolaire. Elle permet de mesurer la déformabilité d'une population de globules rouges (RBC), en fonction de l'osmolalité de milieu. Cette mesure permet un diagnostic différentiel d'un certain nombre de troubles de globules rouges présentant des symptômes similaires. Elle permet également de suivre les effets de certains traitements. Des aspects théoriques qui s’appuient sur les équations des écoulements et une preuve de principe sont discutés. Cette nouvelle technique ouvre la possibilité de construire un instrument simple et peu encombrant, décrit dans ce travail, ne nécessitant qu'un prélèvement de sang au bout du doigt / The ability of red blood cells (RBC) to change their shape under varying conditions is a crucial property allowing these cells to go through capillaries narrower than their own diameter. Ektacytometry is a technique for measuring deformability by exposing a highly diluted blood sample to shear stress and evaluating the resulting elongation in RBC shape using a laser diffraction pattern. This work contributes to the design and evaluation of a new diagnostic technique based on osmotic scan ektacytometry, using a microfluidic method. It allows the measurement of deformability of an RBC population, as a function of varying medium osmolality. This measurement makes possible a differential diagnosis for any one of a number of RBC disorders presenting similar symptoms. It also permits the physician to follow the effects of treatments. Both theoretical aspects based on flow equations and a proof of principle are discussed. This new technique opens up the possibility of building a simple, small footprint instrument described in this work that can be used with finger prick amounts of blood

The current study attempted to shed light on the regulatory processes and response arrangements of fish spermatozoa during the course of maturation and motility initiation. The first intent of this study was to improve the understanding of the mechanism underlying the acquisition of potential for sperm motility in sturgeon. Up to present work, the physiological process underlying sperm maturation in this species has not been described at all. Our results showed that sperm maturation in sturgeon occurs outside the testes because of dilution of sperm by urine and involves the participation of high molecular weight substances as well as calcium ions present in seminal fluid and/or urine. The second aim of the present study was to investigate the coping mechanisms in fish spermatozoa with osmotic and ionic activating mode, as well as in spermatozoa of euryhaline fishes, to various environmental conditions. We showed that alteration of environmental osmolality might affect the fish sperm in different ways, depending on fish species and modes of spermatozoa motility activation either osmotic or ionic mode. In response to osmotic stress caused by hypotonicity, carp spermatozoa regulated the flow of water across their cell membrane and increased their cytoplasmic volume during their short motility period. In contrast, no indications of sperm volume changes were observed neither in sterlet nor in brook trout spermatozoa, both of which having an ionic mode of motility activation. We also examined the mechanism by which sperm motility triggering in euryhaline fishes can adapt to a broad range of environmental salinity. Our results demonstrated that spermatozoa of euryhaline tilapia, Sarotherodon melanotheron heudelotii, reared in fresh-, sea- or hypersaline water can be activated in hypotonic, isotonic or hypertonic conditions of swimming milieu, provided Ca2+ ions are present at various levels. It was established that the higher the fish rearing salinity or the more hypertonic ambient media at spermatozoa activation, the higher extracellular concentration of Ca2+ ions is required. The results obtained in the present study allow suggesting that osmolality is not the main factor inhibiting sperm motility inside the testis in the S. melanotheron heudelotii. A third aim of this study was investigation of the regulation of motility initiation process and description of flagellar beating initiation in chondrostean spermatozoa. We detected that K+ inhibition of sperm motility in sturgeon can be by-passed due to the pre-exposure of sperm cells to a high osmolality shock prior to its transfer to K+-rich swimming media. Thus, we hypothesized that sturgeon spermatozoa may be activated by use of an unexpected signaling pathway, independent from regular ionic stimulation. The successive activation steps in sturgeon spermatozoa were investigated by high-speed video microscopy, using specific experimental situation, where sperm motility initiation was delayed in time up to several seconds. At motility initiation, the first couple of bends formed at the basal region begins to propagate towards the flagellar tip, but gradually fades when reaching the mid-flagellum. This behavior repeats several times until a stage where the amplitudes of bends gradually reach similar value, what eventually leads to sperm progressive displacement. The total period needed for the flagellum to switch from immobility with rigid shape to full activity with regular propagating bends ranges from 0.4 to 1.2 seconds. In conclusion, the results of the current study bring valuable pieces of information into the general understanding of the processes of maturation of fish spermatozoa, their adaptability to different physical and biochemical circumstances, the extra- and intra-cellular signaling as well as the regulatory mechanisms of motility activation in fish spermatozoa.

Extravasation is a condition that can occur during an intravenous administration. This means that the solution administered intravenously goes extravascular. Depending on physiochemical properties of the substance and solution, this can cause different severity of the damage. Extravasation of acyclovir, potassium phosphate and potassium chloride causes severe tissue damage that can, in worst case, lead to tissue necrosis. The purpose was therefore to investigate how acyclovir, potassium phosphate and potassium chloride causes tissue damage due to pH and osmolality and how the tissue damage can be avoided. To answer the purpose, a comprehensive literature search was conducted on three different databases; Pubmed, CINAHL and Cochrane. The literature search was in progress from February 4 to May 14 2020. The literature search generated a total of 42 articles and case reports, of which 13 of these were relevant for the purpose. These 13 articles consisted of two animal studies, three experimental observational studies, two guidelines from Västra Götalands Region, three case reports about acyclovir and three case reports of potassium phosphate and potassium chloride.   Two of the experimental observational studies showed that potassium chloride could be diluted with 100 mL of 0,9% sodium chloride or 5% dextrose in water to possibly avoid tissue damage due to extravasation. Such results were not found for either acyclovir or potassium phosphate. The conclusion that could be drawn was that acyclovir caused tissue damage because of its alkaline pH, potassium phosphate because of its hyperosmolality and potassium chloride because of its acidic pH and its hyperosmolality. One way to possibly avoid tissue damage caused by extravasation is to dilute the substances with higher dilution volumes. However, due to the lack of reliability of the included studies, it cannot be safely concluded that tissue damage can be avoided.