Why is there no carbonic anhydrase activity available to fish plasma?

Carbonic anhydrase (CA) is absent from the plasma of vertebrates. In vitro, CA in fish plasma will short-circuit the effect of catecholamines, which is to increase red blood cell (RBC) pH and volume, both of which enhance the affinity of hemoglobin for O2. CA was infused into trout for a period of 6 h and injected after 48 h, during which the animal was submitted to deep hypoxia (PO2=30­35 mmHg; 4.0­4.7 kPa). O2 content, lactate content, catecholamine levels, hematocrit, hemoglobin concentration and pHi were similar to those in the saline-infused control group. In contrast, cell volume was significantly higher and pHe, total CO2 content and organic phosphate levels were significantly lower than in the control group. The concentration of CA was not high enough completely to short-circuit the increase in pHi and red blood cell volume caused by catecholamines. The lower pHe in the CA-infused animals could enhance the activity of the Na+/H+ pump, which would keep the nucleotide triphosphate levels low. pH is a balance between acid loading at the muscle and acid excretion at the gills or the kidneys; we cannot distinguish between which of these resulted in a decrease of plasma pH. In conclusion, CA in plasma did not cause the expected reduction in blood oxygen content but did have a marked effect on plasma total CO2 content

Potential of vascular endothelial growth factor as a biomarker of coronary artery disease in subjects undergoing CABG surgery

Introduction: • Coronary artery disease (CAD) causes local hypoxia due to reduced blood flow • Hypoxic conditions are known to induce vascular endothelial growth factor (VEGF) production, a key contributor to angiogenesis • The purpose of this study was to determine the potential of VEGF as a marker of myocardial stress in subjects with CAD undergoing coronary artery bypass grafting (CABG) surger

Technology engagement is associated with higher perceived physical well-being in stroke patients prescribed smartwatches for atrial fibrillation detection

BackgroundIncreasing ownership of smartphones among Americans provides an opportunity to use these technologies to manage medical conditions. We examine the influence of baseline smartwatch ownership on changes in self-reported anxiety, patient engagement, and health-related quality of life when prescribed smartwatch for AF detection.MethodWe performed a post-hoc secondary analysis of the Pulsewatch study (NCT03761394), a clinical trial in which 120 participants were randomized to receive a smartwatch-smartphone app dyad and ECG patch monitor compared to an ECG patch monitor alone to establish the accuracy of the smartwatch-smartphone app dyad for detection of AF. At baseline, 14 days, and 44 days, participants completed the Generalized Anxiety Disorder-7 survey, the Health Survey SF-12, and the Consumer Health Activation Index. Mixed-effects linear regression models using repeated measures with anxiety, patient activation, physical and mental health status as outcomes were used to examine their association with smartwatch ownership at baseline.ResultsNinety-six participants, primarily White with high income and tertiary education, were randomized to receive a study smartwatch-smartphone dyad. Twenty-four (25%) participants previously owned a smartwatch. Compared to those who did not previously own a smartwatch, smartwatch owners reported significant greater increase in their self-reported physical health (β = 5.07, P < 0.05), no differences in anxiety (β = 0.92, P = 0.33), mental health (β = −2.42, P = 0.16), or patient activation (β = 1.86, P = 0.54).ConclusionsParticipants who own a smartwatch at baseline reported a greater positive change in self-reported physical health, but not in anxiety, patient activation, or self-reported mental health over the study period

Why is there no carbonic anhydrase activity available to fish plasma?

Carbonic anhydrase (CA) is absent in the plasma of vertebrates. In vitro, CA in fish plasma will short-circuit the effect of catecholamines on the increase in red blood cell (RBC) pH and volume, both of which increase the hemoglobin affinity for O₂. CA was infused into trout for a period of 6h during which the animal was submitted to deep hypoxia (PO₂= 30-35 torr) and during recovery after exhaustive exercise. During hypoxia, O₂ content, lactate, catecholamines, hematocrit, hemoglobin and pHi were similar to the saline infused control group. On the other hand, cell volume was significantly higher and PHe, total CO₂ and organic phosphates were significantly lower than the control group. The concentration of CA was not high enough to completely short-circuit the increase in pHi and RBC volume caused by catecholamines. The lower pH in the CA infused animals could enhance the activity of the Na+/H+ pump which would keep the NTP low. CA in plasma, during hypoxia, did not cause the expected reduction in blood oxygen content but did have a marked effect on plasma total CO₂. During the recovery period of exhaustive exercise, lactate, catecholamines, hematocrit, hemoglobin, MCHC, PO₂, HbO₂, and pHi were similar to the saline infused animals. Total CO₂ and PHe were significantly higher in the CA infused fish than in the saline infused ones. CA infusion, in this case, probably caused acid retention in the muscle. Acid efflux from the muscle would decrease pH or if the acid was excreted at the gills, bicarbonate would be titrated and the stores would be lower than in control animals. CA activity available to plasma would mean greater fluctuation of plasma pH, at least in hypoxic conditions, and red blood cell pH in general. pH is a balance between acid loading at the muscle and acid excretion at the gills or the kidneys, we cannot distinguish between a decrease and an increase of one of the two which resulted in a decrease of plasma pH. Fish have a large Haldane effect and HCO₃ flux through the red cell ensures that the protons are excreted as CO₂ and cannot bind again to hemoglobin. The absence of CA in the plasma ensures that HCO₃ flux through the red cell is maintained.Science, Faculty ofZoology, Department ofGraduat

Les contraintes et opportunités organisationnelles des nouvelles technologies d'intégration : le cas d'un outil "case"

Les "impacts" de la technologie sur l'organisation -- L'entreprise -- La nouvelle technologie -- Les changements organisationnels reliés au changement technologique -- Le poids de la gestion du changement technologique -- La gestion technique du changement -- La gestion organisationnelle du changement -- La modulation opérée par la gestion organisationnelle du changement

Les contraintes et opportunités organisationnelles des nouvelles technologies d'intégration : le cas d'un système médico-administratif dans un hôpital

Les "impacts" de la technologie sur l'organisation -- L'entreprise -- La nouvelle technologie -- Les changements organisationnels reliefs au changement technologique -- Le poids de la gestion du changement technologique -- La gestion technique du changement -- La gestion organisationnelle du changement -- La modulation opérée par la gestion organisationnelle du changement

Effects of hypoxia on rainbow trout (Oncothynchus mykiss): Intraerythrocytic phosphates

Intraerythrocytic levels of guanosine and adenosinephosphates were estimated in normoxic and hypoxicrainbow trout after intra-arterial injection with eithersaline or carbonic anhydrase. A significant reduction of thetotal pool of adenosine and guanosine was observed inhypoxic animals. Similarly, a decrease in both ATP andGTP levels occurred in hypoxic animals injected eitherwith saline or with carbonic anhydrase. Interestingly, therewas a highly significant relationship between ATP andGTP levels, indicating that they are under similar control.In addition, a significant positive relationship betweennucleoside triphosphate (NTP) and Mg2+levels wasobserved. It is possible that the availability of ATP andGTP to hemoglobin (Hb) may be proportionally smallerthan their intraerythrocytic absolute levels. No clearrelationship between intraerythrocytic NTP levels andplasma carbonic anhydrase infusion was observed, despitethe significant effect of carbonic anhydrase on acid–basebalance. There was a significant relationship between redblood cell pH and [NTP]:[Hb] in fish exposed to hypoxiafor 48h. No such relationship existed during the first 6h ofhypoxic exposure. Possible mechanisms accounting for thereduction in NTP levels during the initial phases of hypoxiaare discusse