Search results for "Extracellular fluid"
showing 10 items of 27 documents
Distribution of sea urchins living near shallow water CO2 vents is dependent upon species acid-base and ion-regulatory abilities.
2013
To reduce the negative effect of climate change on Biodiversity, the use of geological CO2 sequestration has been proposed; however leakage from underwater storages may represent a risk to marine life. As extracellular homeostasis is important in determining species' ability to cope with elevated CO2, we investigated the acid-base and ion regulatory responses, as well as the density, of sea urchins living around CO2 vents at Vulcano, Italy. We conducted in situ transplantation and field-based laboratory exposures to different pCO2/pH regimes. Our results confirm that sea urchins have some ability to regulate their extracellular fluid under elevated pCO2. Furthermore, we show that even in cl…
How Glutamate Is Managed by the Blood-Brain Barrier.
2016
A facilitative transport system exists on the blood–brain barrier (BBB) that has been tacitly assumed to be a path for glutamate entry to the brain. However, glutamate is a non-essential amino acid whose brain content is much greater than plasma, and studies in vivo show that glutamate does not enter the brain in appreciable quantities except in those small regions with fenestrated capillaries (circumventricular organs). The situation became understandable when luminal (blood facing) and abluminal (brain facing) membranes were isolated and studied separately. Facilitative transport of glutamate and glutamine exists only on the luminal membranes, whereas Na+-dependent transport systems for g…
Chronic hyponatremia in a patient with renal salt wasting and without cerebral disease: relationship between RSW, risk of fractures and cognitive imp…
2018
Renal salt wasting syndrome (RSW) is defined as a renal loss of sodium leading to hyponatremia and a decrease in extracellular fluid volume (ECV). Differentiation of this disorder from the syndrome of inappropriate antidiuretic hormone secretion (SIADH), a common cause of hyponatremia, can be difficult because both can present with hyponatremia and concentrated urine with natriuresis. Our clinical case about a 78-year-old woman with a recent fracture of the right femur not only confirms that this syndrome can occur in patients without intracranial pathologies (CT documented), but depicts how the hyponatremia caused by RSW can show a chronic, oscillating course. This is an interesting point …
Expanded gentamicin volume of distribution in critically ill adult patients receiving total parenteral nutrition
1995
Aminoglycoside antibiotics distribute into the extracellular fluid compartment and are eliminated by the kidney via glomerular filtration. Malnutrition and total parenteral nutrition influence the fluid and electrolyte status of the patient, and cause organ changes. The purpose of this clinical study was to characterize the kinetic behaviour of gentamicin in the parenterally fed critically ill adult patient. Eighty-six critically ill adult patients treated with gentamicin for severe Gram-negative infections were enrolled in the study (mean +/- SD): age, 60 +/- 14 years; weight, 69.4 +/- 10.2 kg; height, 163 +/- 10 cm; 22 females and 64 males. Four study groups were defined (2 x 2): total pa…
Feeding enhances extracellular lactate of local origin in the rostromedial hypothalamus but not in the cerebellum.
1999
Abstract The use of brain microdialysis together with chronic vascular catheterization allowed us to assay extracellular fluid lactate (ECF L ) in both the ventromedial–paraventricular (VMH–PVN) area of the hypothalamus and the cerebellum, in parallel with measures of plasma levels, and in relation to food intake. A 45 min scheduled meal increased VMH–PVN ECF L by 28%. This increase was not observed in the cerebellum. The prandial increase in plasma glucose (43%, from 4.74 to 6.77 mM) and lactate (84%, from 0.83 to 1.53 mM) showed a different temporal pattern and lasted longer than that of the ECF L . Glucose delivery by reverse dialysis for 45 min into the VMH–PVN area increased ECF L by 4…
Simulation Analysis of the Influence of Hemodialysis Control Parameters on Exchange Processes during Therapy
1992
The effect of dialysis control parameters (dialysate composition, ultrafiltration rate, blood flow rate) on the patient's internal milieu were studied using a mathematical model for the description of the dynamic exchange processes during hemodialysis. This model simulates the electrolyte and water distribution, the acid-base and the oxygenation state as well as the ventilation. The dialysate sodium concentration affects mainly the intra-/ extracellular water and the potassium distribution. The dialysate bicarbonate and acetate concentrations control the acid-base state and the electrolyte distribution (sodium and potassium). In addition, the dialysate acetate concentration has a strong ef…
Central cholinergic functions in human amyloid precursor protein knock-in/presenilin-1 transgenic mice.
2004
Alzheimer's disease is characterized by amyloid peptide formation and deposition, neurofibrillary tangles, central cholinergic dysfunction, and dementia; however, the relationship between these parameters is not well understood. We studied the effect of amyloid peptide formation and deposition on central cholinergic function in knock-in mice carrying the human amyloid precursor protein (APP) gene with the Swedish/London double mutation (APP-SL mice) which were crossbred with transgenic mice overexpressing normal (PS1wt) or mutated (M146L; PS1mut) human presenilin-1. APP-SLxPS1mut mice had increased levels of Abeta peptides at 10 months of age and amyloid plaques at 14 months of age while AP…
The Complementary Membranes Forming the Blood-Brain Barrier
2002
Brain capillary endothelial cells form the blood-brain barrier. They are connected by extensive tight junctions, and are polarized into luminal (blood-facing) and abluminal (brain-facing) plasma membrane domains. The polar distribution of transport proteins allows for active regulation of brain extracellular fluid. Experiments on isolated membrane vesicles from capillary endothelial cells of bovine brain demonstrated the polar arrangement of amino acid and glucose transporters, and the utility of such arrangements have been proposed. For instance, passive carriers for glutamine and glutamate have been found only in the luminal membrane of blood-brain barrier cells, while Na-dependent second…
Structure of the Blood–Brain Barrier and Its Role in the Transport of Amino Acids
2005
Brain capillary endothelial cells form the blood-brain barrier (BBB). They are connected by extensive tight junctions, and are polarized into luminal (blood-facing) and abluminal (brain-facing) plasma membrane domains. The polar distribution of transport proteins mediates amino acid (AA) homeostasis in the brain. The existence of two facilitative transporters for neutral amino acids (NAAs) on both membranes provides the brain access to essential AAs. Four Na(+)-dependent transporters of NAA exist in the abluminal membranes of the BBB. Together these systems have the capability to actively transfer every naturally occurring NAA from the extracellular fluid (ECF) to endothelial cells and from…
Validation of brain extracellular glycerol as an indicator of cellular membrane damage due to free radical activity after traumatic brain injury.
2008
Following severe traumatic brain injury (TBI), increasing oxygen delivery to the brain has been advocated as a useful strategy to reverse mitochondrial dysfunction and improve neurological outcome. However, this might also promote overproduction of free radicals, responsible for lipid peroxidation and hence brain cell damage. Therefore, a method for monitoring this potential adverse effect in humans is desirable. Glycerol, an end product of phospholipid breakdown, easily detectable in the human brain by means of microdialysis, might represent a reliable indicator of free radical-induced cell membrane damage. Brain microdialysates were collected from 24 adult male Sprague-Dawley rats over a …