We sought to determine if compensatory vasodilator and/or pressor responses protect exercising muscle O2 delivery (O2D) under conditions of reduced arterial perfusion pressure, if this is exercise intensity-dependent, and if distinct cardiovascular response phenotypes exist. Ten healthy male subjects (19.5±0.4 years) completed two trials of a ramp protocol forearm isometric handgrip exercise test to exhaustion (2.5 kg increments every 3.5 minutes) in each of forearm above and below heart level (forearm arterial perfusion pressure (FAPP) difference of 29.5±0.97 mmHg). Forearm blood flow ((FBF (ml/min; brachial artery Doppler and echo ultrasound), mean arterial blood pressure (MAP; finger photoplethysmography), and exercising forearm venous effluent (ante-cubital vein catheter) measurements at the end of each work rate (WR) revealed the following. Group level (n=10) Δ FBF was compromised beyond 5 kg WR in above vs. below (P<0.05). There was no evidence of compensatory vasodilator (P=0.21) or pressor (P=0.63) responses. Peak O2D, WR and VO2 were significantly compromised by reduced FAPP (115.6±16.8 vs. 152.0±13.4 mlO2/min, 25.5±1.22 vs. 28.94±1.50 kg and 75.9±5.3 vs. 100.2±8.6 ml/min; P<0.05). In contrast, examination of individual responses revealed distinct cardiovascular response groups with (n=6) vs. without (n=4) compensatory vasodilation with the former having less compromise to submaximal O2D and peak WR (-94.12±23.42 vs. -223.40±36.01 mlO2/min), P<0.05 and -2.5±0.32 vs. -5.32±0.79 kg, P<0.05). In conclusion, exercising forearm muscle hypoperfusion due to reduced FAPP is not compensated for by pressor responses. However, there appear to be distinct phenotypes in which vasodilatory compensation does vs. does not occur, which in the former partially protects O2D and exercise performance. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2012-09-13 16:42:41.751

Articular cartilage disorders are a leading cause of human disability in many countries around the world. In this work, new techniques and strategies were developed to improve the quality of cartilage produced in vitro by methods of tissue engineering. Chondrocytes were isolated from the hip and knee joints of aborted human foetuses. The cells were expanded and seeded into scaffolds and the seeded scaffolds were cultured in perfusion bioreactors. The quality of the final cartilage constructs was assessed biochemically by measuring their content of glycosaminoglycan (GAG), total collagen and collagen type II and histologically by staining cross-sections of the constructs for GAG, collagen type I and collagen type II. The amount of proteoglycan released in the culture medium was also measured at regular intervals. Proteoglycans from tissue-engineered cartilage and spent culture medium were compared and analysed for degradation and capability of aggregation. During monolayer expansion, the chondrocyte differentiation indices decreased, the cell size increased and the percentage of cells present in G2/S??M phase decreased with the greatest changes occurring during the first passage. Expanding chondrocytes in PGA or PGA??alginate scaffolds produced cells with a higher level of differentiation than monolayer-expanded cells. However, PGA and PGA??alginate could not be justified as suitable systems for the routine expansion of chondrocytes mainly because of the relatively low cell proliferation obtained. Two new methods for seeding of cells into scaffolds were investigated using PGA and PGA??alginate as scaffold materials. Both methods produced high seeding efficiencies and homogeneous distribution of cells. When seeded PGA??alginate scaffolds were cultured in perfusion bioreactors, they produced good quality constructs with higher concentrations of extracellular matrix (ECM) components compared with previously described methods. However, when seeded PGA scaffolds were cultured in perfusion bioreactors, they produced small constructs of poor quality. Investigation of the effect of medium flow rate on the PGA scaffolds showed that a low flow rate was needed at the beginning of the culture to enable the cells to form a framework onto which other synthesised elements could deposit. Applying a gradual increase in medium flow rate to PGA scaffolds cultured in perfusion bioreactors solved the shrinkage problem and produced constructs with quality similar to those produced using PGA??alginate scaffolds. A novel compression bioreactor that mimicked the physiological stimulation of cartilage by joint movement was constructed. Using this bioreactor, compressed constructs showed significantly higher wet weight and higher concentrations of GAG, total collagen and collagen type II compared with non-compressed constructs.

Articular cartilage disorders are a leading cause of human disability in many countries around the world. In this work, new techniques and strategies were developed to improve the quality of cartilage produced in vitro by methods of tissue engineering. Chondrocytes were isolated from the hip and knee joints of aborted human foetuses. The cells were expanded and seeded into scaffolds and the seeded scaffolds were cultured in perfusion bioreactors. The quality of the final cartilage constructs was assessed biochemically by measuring their content of glycosaminoglycan (GAG), total collagen and collagen type II and histologically by staining cross-sections of the constructs for GAG, collagen type I and collagen type II. The amount of proteoglycan released in the culture medium was also measured at regular intervals. Proteoglycans from tissue-engineered cartilage and spent culture medium were compared and analysed for degradation and capability of aggregation. During monolayer expansion, the chondrocyte differentiation indices decreased, the cell size increased and the percentage of cells present in G2/S??M phase decreased with the greatest changes occurring during the first passage. Expanding chondrocytes in PGA or PGA??alginate scaffolds produced cells with a higher level of differentiation than monolayer-expanded cells. However, PGA and PGA??alginate could not be justified as suitable systems for the routine expansion of chondrocytes mainly because of the relatively low cell proliferation obtained. Two new methods for seeding of cells into scaffolds were investigated using PGA and PGA??alginate as scaffold materials. Both methods produced high seeding efficiencies and homogeneous distribution of cells. When seeded PGA??alginate scaffolds were cultured in perfusion bioreactors, they produced good quality constructs with higher concentrations of extracellular matrix (ECM) components compared with previously described methods. However, when seeded PGA scaffolds were cultured in perfusion bioreactors, they produced small constructs of poor quality. Investigation of the effect of medium flow rate on the PGA scaffolds showed that a low flow rate was needed at the beginning of the culture to enable the cells to form a framework onto which other synthesised elements could deposit. Applying a gradual increase in medium flow rate to PGA scaffolds cultured in perfusion bioreactors solved the shrinkage problem and produced constructs with quality similar to those produced using PGA??alginate scaffolds. A novel compression bioreactor that mimicked the physiological stimulation of cartilage by joint movement was constructed. Using this bioreactor, compressed constructs showed significantly higher wet weight and higher concentrations of GAG, total collagen and collagen type II compared with non-compressed constructs.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 5 uppsatser.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Includes bibliographical references (p. 126-136).

As one of the most successful invasive species in the marine environment around the globe, the green crab Carcinus maenas possesses efficient regulatory mechanisms to quickly acclimate to environmental changes. The most important organs in this process are the nine pairs of gills that not only allow for osmoregulation, but have been shown to be involved in ammonia excretion and respiratory gas exchange. To date, however, little is known about the gills’ contribution to acid-base regulation that might become increasingly important in a “future ocean scenario” whereby surface ocean pH is predicted to drop by up to 0.5 units by the year 2100. The present thesis aims to characterize the green crab gills’ role in acid-base regulation and how it is linked to ammonia excretion. After exposure to hypercapnia (0.4 kPa pCO2 for 7 days), osmoregulating green crabs were capable of fully compensating for the resulting extracellular respiratory acidosis, while osmoconforming green crabs only partially buffered the accompanying drop in hemolymph pH after acclimation to 1% CO2 for 48 hours. Perfusion experiments on isolated green crab gills showed that different gills contributed to the excretion of H+ in an individual pattern and indicated that NH4+ is an important component of branchial acid excretion. Experiments on gill mRNA expression and pharmaceutical effects on isolated gills identified distinct epithelial transporters to play significant roles in branchial acid base regulation: Rhesus-like protein, basolateral bicarbonate transporter(s), cytoplasmic V-(H+)-ATPase, Na+/H+-exchanger, basolateral Na+/K+-ATPase, cytoplasmic and membrane bound carbonic anhydrase, and basolateral K+ channels. Regarding the latter, the present work provides the first sequence-based evidence for a potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel (CmHCN) capable of promoting NH4+ transport in the green crabs’ gill epithelium, and further demonstrates its direct involvement in branchial acid-base regulation. This highly conserved protein is a potentially important novel key-player in acid-base regulation in all animals. Interestingly, the observed principles linking acid-base to ammonia regulation in the decapod crustacean gill epithelium resemble many observations previously made in vertebrates. The data of the present thesis therefore provides valuable information for general acid-base regulation, while contributing substantially to our understanding of acid-base regulation in invertebrates. / February 2016

The global occurrence of metabolic syndrome has reached epidemic proportions and is a contributing factor in the rising incidence of cognitive decline in the aging population. While pre-clinical research has advanced our understanding of many of the mechanisms underlying metabolic syndrome, animal models often do not reflect the complexity of human disease. For example, animal models that investigate the role played by diet in metabolic syndrome have generally focused on a single macronutrient, in particular fat or carbohydrate. As a result, although a balanced diet and increased physical activity are commonly recommended to treat metabolic syndrome symptomatology, their long-term cerebrovascular benefits are uncertain. To address these gaps in knowledge, a “Cafeteria” diet consisting of 16 common ultra-processed grocery store food items was used to model human metabolic syndrome in the rat. I compared rats fed a Cafeteria diet (CAF) to those fed “standard” chow (SD) as well as to a third group that underwent a switch to chow after chronic exposure to the Cafeteria diet (SWT). In a first study, I showed that three months of exposure to the Cafeteria diet produced metabolic syndrome as well as hippocampal neuroinflammation with increased microglial proliferation. These were fully reversed in SWT rats. Nonetheless, the Cafeteria diet did not worsen spatial learning and memory performance as assessed using the Barnes maze. In a second study, brain perfusion was examined using continuous arterial spin labeling magnetic resonance imaging (CASL MRI). Cortical and hippocampal resting perfusion was increased in CAF rats while cerebrovascular reactivity in response to a 10% CO2 vasodilatory challenge was reduced. Furthermore, while resting perfusion improved in SWT rats, cerebrovascular reactivity remained impaired. These cerebral blood flow outcomes were not accompanied by alterations in microvascular architecture or integrity as determined by rat endothelial cell antigen-1 (RECA-1) and immunoglobulin G (IgG) histology. Taken together, these results demonstrate that the Cafeteria diet is an effective model of metabolic syndrome that negatively impacts brain hemodynamic function. Moreover, while a dietary lifestyle intervention can recover peripheral features of metabolic syndrome, neuroinflammation, and resting perfusion, it is insufficient to completely reverse deficits in cerebrovascular reactivity. These findings are compelling as they speak to the detrimental effects of ultra-processed food consumption on cerebrovascular reserve capacity, believed to be an important factor in cognitive decline.

Myocardial Perfusion Imaging (MPI) and Coronary Angiography (CA) are two methods that can be used in the investigation of ischemic heart disease. The purpose of this study is to compare medical answers from MPI and CA to find out if suspected coronary artery disease shown with MPI correlates with coronary artery morphology shown with CA, and which treatment is given based on Summed Difference Percent (SD%). The study population consists of 45 patients. The information has been retrieved retrospectively at Länssjukhuset Ryhov. Included patients had coronary heart disease accessible for percutan coronary intervention. Out of the total data sample the results show an occurring difference when it comes to medical answers from MPI and CA. The results show that most of the study participants with SD% &lt;10 obtained solely drug treatment. Those with SD% &gt;10 were given treatments not always according to guidelines. Elements that might have had an impact on the result is discussed. In conclusion, it appears that there is a difference in some medical answers which may be a caused of collateral circulation which causes the wrong coronary artery area to be determined as ischemic based on the MPI or because of a misinterpretation of an exam.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / As macroalgas sÃo encontradas em todo o mundo, desempenhando um importante papel na manutenÃÃo do equilibrio marinho e na preservaÃÃo da biodiversidade marinha. Estudos com espÃcies de macroalgas presentes no litoral do CearÃ, como a Caulerpa cupressoide e Pterocladiella capillacea tem despertado interesse por diversos efeitos biolÃgicos. A Caulerpa cupressoides à uma alga verde da famÃlia Caulerpaceae e a Pterocladiella capillacea trata-se de uma alga vermelha da familia Pterocladiacea. Diante do potencial destas espÃcies e de seus componentes como as lectinas, bem como de poucos relatos sobre efeitos tÃxicos renais objetivou-se estudar os efeitos das lectinas das algas citadas em modelo de perfusÃo renal, efeitos citotÃxicos em cÃlulas MDCK e efeitos na PressÃo Arterial (PA) e Frequencia Cardiaca (FC). Utilizou-se ratos wistar machos, pesando entre 250 e 300g. Na perfusÃo de rins isolados utilizou-se as lectinas na concentraÃÃo de 10Âg/mL. Os efeitos das lectinas foram avaliados na PressÃo de PerfusÃo(PP), ResistÃncia Vascular Renal(RVR), Fluxo UrinÃrio(FU), Ritmo de FiltraÃÃo Glomerular (RFG), Percentual do transporte tubular de sÃdio (%TNa+), de potÃssio (%TK+) e de cloreto (%TCl-). O ensaio com artÃria mesentÃrica foi realizado com a lectina da Caulerpa cupressoides (Lcc) nas concentraÃÃes de 0,1; 0,3; 1; 3; 10; 30; 60; 100; 200; 300 e 400 Âg/mL e o tecido foi pre-contraÃdo com fenilefrina(PHE) (0,3Âmol e 1Âmol). A PA e FC foram obtidas por canulaÃÃo da carÃtida e os registros realizados atravÃs de um software de aquisiÃÃo de dados. A LCc aumentou a PP e RVR aos 90 e 120 minutos, reduziu o RFG aos 60 minutos e reduziu o %TNa+, %TK+ e %TCl- aos 60, 90 e 120 minutos. A lectina da Pterocladiela capillacea (LPc) reduziu o FU aos 120 minutos e reduziu o %TNa+, aos 90 e 120 minutos. No estudo de citotoxidade, a LCc e LPc nÃo alteraram a viabilidade de cÃlulas MDCK. A LCc promoveu relaxamento em artÃria mesentÃrica nas concentraÃÃes de 100, 200, 300 e 400 Âg/mL em tecido prÃ-contraido com PHE 1 Âmol, mas nÃo o fez em tecido prÃ-contraido com PHE 0,3 Âmol abaixo de 200 Âg/mL. A LCc promoveu deposiÃÃo de material protÃico nos espaÃos tubular e urinÃrio e expansÃo do intersticio. A LPc causou minima desposiÃÃo de material protÃico, sem alteraÃÃes a nivel de intersticio. A LCc causou leve reduÃÃo na PA nas concentraÃÃes de 100 e 200Âg/mL e nÃo alterou a FC e a LPc nÃo causou alteraÃÃes da PA e FC. Observou-se que a LCc promoveu efeitos hemodinÃmicos renais, aumentando PP e RVR o que pode ser em decorrÃncia de ativaÃÃo de &#945;-adrenoreceptores. A LCc reduziu a PA a partir de100 Âg/mL, sugerindo possÃvel liberaÃÃo de agentes vasodiltadores, o que ocasionaria tambÃm acÃmulo de lÃquido no intersticio (edema) como mostrou a histologia dos rins. A LPc nÃo promoveu alteraÃÃes na PP e RVR. A FC e PA nÃo foram alteradas com a LPc sugerindo que a mesma nÃo promove liberaÃÃo de substÃncias que agem diretamente como vasoconstritores. / Macroalgae are found worldwide, playing an important role in maintaining the balance marine and conservation of marine biodiversity. Studies with seaweeds present in the coast of CearÃ, such as Caulerpa cupressoides and Pterocladiella capillacea has aroused interest in many biological effects. The Caulerpa cupressoides is a green algae belonging to the family Caulerpaceae and Pterocladiella capillacea is a red seaweed of the family Pterocladiacea. Given the potential of these species and their components such as lectins, as well as a few reports of kidneys toxic effects aimed to study effects of lectins cited algae on renal perfusion model, cytotoxic effects on MDCK cells, effects on Blood Pressure (BP) and Heart Rate(HR). Male Wistar rats weighing between 250 and 300g were used in the experiments. Lectins was utilized in perfusion of isolated kidneys at concentration of 10&#956;g/mL. The effects of lectins were evaluated in Pressure Perfusion (PP), Renal Vascular Resistance (RVR), Urinary Flow (FU), Glomerular Filtration Rate (GFR), Percentage of Tubular Transport of Sodium (% TNa+), Potassium (% TK +) and Chloride (%TCl-). The mesenteric artery assay was realized with the lectin Caulerpa cupressoide- LCc at concentrations of 0.1, 0.3, 1, 3, 10, 30; 60, 100, 200, 300 and 400&#956;g/mL., and the tissue was pre-contracted with phenylephrine (PHE) (0.3&#956;mol and 1&#956;mol). The BP and HR were obtained by cannulation of the carotid artery and registers performed by a data acquisition software. The LCc increased RVR and PP at 90 and 120 min, reduced GFR at 60 minutes and reduced the % TNa+, % TK+ and %TCl- at 60, 90 and 120 minutes. The lectin Pterocladiella capillaceae -LPc reduced the FU at 120 minutes and reduction % TNa+, at 90 and 120 minutes. In the study of cytotoxicity, LCc and LPc did not affect viability of MDCK cells. LCc promoted relaxation in mesenteric artery in concentrations of 100, 200, 300 and 400 Âg/mL in tissue pre-contracted with PHE to 1.0 micromol, but did not it in tissue pre-contracted with PHE a 0.3 micromol, in concentrations below to 200 Âg/mL. LCc promoted deposition of protein material in the tubule and expansion interstice. The LPc caused deposition protein material in the tubule, without changes at the level of interstice. LCc caused slight reduction in blood pressure at concentrations of 100 and 200&#956;g/mL and did not change the Cardiac Frequency (CF) and LPc caused no changes in CF nor the Heart Rate (HR). It was noted that the LCc promoted renal hemodynamic effects, raising PP and RVR, which may be due to &#945;-adrenoceptor activation. LCc reduced the BP from the concentration of 100 &#956;gmL, suggesting possible release of agents vessel dilators, which also would cause fluid accumulation in the interstice as shown kidney histology. LPc did not change the PP and RVR. The HR and BP were not changed with the LPc, suggesting that it does not promote the release of substances that act directly as a vasoconstrictor.

Abstract Cessation of the blood circulation for some time during surgery of the aortic arch and repair of congenital heart defects is normally required to allow a bloodless operation field. Hypothermia is the most important mechanism for end-organ protection, particularly the brain, during such operations. Cardiopulmonary bypass is used for core cooling before total hypothermic circulatory arrest (HCA) or selective cerebral perfusion (SCP) are initiated. During hypothermic cardiopulmonary bypass, pH can be managed according to either pH- or alpha-stat principles. In the present work, the optimal pH management strategy for operations requiring HCA or SCP was explored. An experimental porcine model was used. Firstly, outcome was evaluated in a HCA model using either the α- or pH-stat perfusion strategy (I). Secondly, we sought to determine which acid-base management is more effective in attenuating ischemic brain injury during combined HCA and embolization conditions (II). In the third study, the impact of propofol anesthesia and α-stat perfusion strategy on outcome was explored (III). Finally, the acute effects of perfusion strategies in a SCP porcine were compared (IV). Hemodynamics, temperature, EEG (I-III), brain microdialysis, intracranial pressure (I-III), brain tissue oxygen partial pressure (I-III), and intravital microscopy (IV) were monitored intraoperatively. In the chronic studies, survival, postoperative neurologic recovery and brain histopathologic examination were evaluated (I-III). pH-stat strategy was associated with superior outcome compared to the α-stat strategy during a 75-minute period of deep HCA (I). In addition, despite the pH-stat strategy-related cerebral vasodilatation, this method provided better neuroprotection in a setting of cerebral particle embolization prior to a 25-minute period of deep HCA (II). Propofol anesthesia combined with α-stat perfusion strategy was observed to deteriorate the brain injury during HCA evaluated by key brain microdialysis parameters (III). Finally, when employing moderately hypothermic SCP, the differences between pH- and α-stat strategies in cerebral metabolism and microcirculation were minimal. These findings are clinically relevant since α-stat perfusion strategy is still the most commonly used acid-base perfusion strategy during hypothermic cardiopulmonary bypass in adults, and propofol one of the most used anesthetics in clinical practice. It is also noteworthy that the pH-stat strategy is not currently used in adults because of the perceived increased risk of atherosclerotic embolization. However, the advantage of pH-stat strategy over α-stat strategy could not be observed when employing SCP.