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Biomedical subjects

A Murisasco

Publications and source records attributed to A Murisasco.

At least 19 recordsLinked to original sources
PubMed1990

Kinetic modeling of intradialytic and interdialytic pH shifts during and after acetate and bicarbonate hemodialysis.

A kinetic model involving intraerythrocytic and whole blood H+ concentrations during and after bicarbonate and acetate hemodialysis is proposed to account for experimental data. A two-compartment model appeared to be the simplest kinetic model to explain the decrease in proton concentration during bicarbonate hemodialysis and its increase between two dialysis sessions, whether acetate or bicarbonate. This model takes into account the hemoglobin buffer power and the cellular metabolic acidosis. During acetate hemodialysis, one must introduce a new compartment to explain the initial increase in H+ concentration in erythrocytes. This compartment, which generates protons, seems to correspond to the carbonic anhydrase cycle. The various parameters obtained show no significant variations between patients receiving bicarbonate hemodialysis. For acetate hemodialysis, the model describes equally well patients with a great initial increase in H+ concentration and those with a slight initial increase. The variations observed in the parameters are due mainly to the carbonic anhydrase compartment. It is suggested the magnitude of this initial increase and the degree of acetate intolerance are correlated.

Acetates↗
PubMed1990

Kinetic modeling of intracellular pH and comparison with 31P NMR experimental values in dialysed uremic patients.

Changes in intra-erythrocytic pH values over time, during and after bicarbonate hemodialysis, were studied with 31P Nuclear Magnetic Resonance. Simultaneously, pH values of whole blood were obtained by a gazometric method. A two-compartment model appeared to be the simplest kinetic model to explain the shifts in proton concentrations in extra- and intra-cellular media. Non-linear regression was used to determine exchange constant values. There was a very good correlation between the experimental and calculated proton concentrations. This model can describe all patients but individual experimental constants must be determined. Under these conditions a single blood pH determination before dialysis will permit determination of the initial intra-erythrocytic pH and monitoring of intra-erythrocytic pH during hemodialysis.

Acid-Base Equilibrium↗
PubMed1989

Phosphorus-31 and water proton relaxation in living erythrocytes. Application to uremia.

We measured the spin-lattice and spin-spin relaxation times (T1 and T2, respectively) and the nuclear Overhauser effect (NOE) of 31P nuclei of 2,3-diphosphoglycerate (2,3-DPG) in living erythrocytes. The relaxation of water protons was also studied. Phosphorus relaxation is pH-dependent due to a modification of the binding of 2,3-DPG to hemoglobin. We compared the results obtained with normal and uremic erythrocytes. In uremic erythrocytes the 31P relaxation rates are increased, but the intraerythrocytic pH variation in uremic erythrocytes cannot itself explain this increase. A possible role of dialysable substances may explain the increased relaxation rate.

2,3-Diphosphoglycerate↗
PubMed1989

Intraerythrocytic pH variations during hemodialysis: a 31P NMR study.

Before hemodialysis, patients have an intraerythrocytic pH (pHi) and an extracellular pH, measured in whole blood (pHo), which are lower than those of healthy controls. During bicarbonate hemodialysis, pHi values continuously increase, approaching a normal value at the end of the session. Concomitantly, pHo values follow similar variations. During acetate hemodialysis, pHi values exhibit a steep initial decrease, reaching a minimum after about 15 minutes. Concurrently, however, pHo values decrease only slightly. This phenomenon seems to originate in the intraerythrocytic medium and might be due to a shift in intracellular CO2/bicarbonate equilibrium. This drop in pHi exhibits interpatient variability, suggesting that the magnitude of pH decrease would be correlated with the degree of the problems observed in some patients undergoing acetate hemodialysis.

Acetates↗
PubMed1988

23Na nuclear magnetic resonance study of Na+-K+ pump inhibition by a fraction from uremic toxins.

An in vitro inhibitor of Na+/K+-transporting ATPase (EC 3.6.1.37) was isolated from uremic plasma and normal urine by liquid chromatography. A 23Na nuclear magnetic resonance study involving living erythrocytes showed that this inhibitor causes impairment of the Na+-K+ pump of intact erythrocytes. This finding may explain the high intra-erythrocytic sodium concentration in those uremic patients exhibiting a high concentration of this inhibitor. The presence of this same inhibitor in normal urine suggests that it may play a physiological role.

Animals↗
PubMed1987

[Pseudo-hypertrophic pelvi-crural amyloid myopathy in lambda light-chain myeloma. Clinical, morphological and immunocytochemical study].

The case of 65 year old woman with progressive enlargement and "wooden" induration of the pelvic girdle and thigh muscles due to an amyloid infiltration is reported. Muscle changes appeared two years after a diagnosis of myeloma with free lambda light chains. The patient complained of muscle pain, lassitude and weakness. Macroglossia was present. Skeletal muscle (vastus lateralis) contained large amounts of amyloid substance and showed type 2B atrophy. There was no fiber type grouping. Some amyloid deposits abutted on the muscle fiber, destroyed the basal lamina and sarcolemma, but never infiltrated it. Besides the amyloid phagocytosis by macrophages, a relationship between amyloid filaments and fibroblasts was present. Another non-congophilic substance was revealed using the Avidin-Biotin peroxidase complex to localize lambda light chains by light microscopy and corresponded to a granular substance in electron microscopy. Clinicopathological results are discussed with a review of thirteen similar cases previously reported.

Aged↗
PubMed1987

Modification of intra-erythrocytic homeostasis in uremic patients, as studied with 31P nuclear magnetic resonance.

Intra-erythrocytic pH, ATP concentrations, and 2,3-diphosphoglycerate relaxation times were studied in living erythrocytes by "high-resolution" 31P NMR spectroscopy to assess homeostasis within the cells. In uremic patients, intra-erythrocytic pH is significantly decreased before hemodialysis, but is corrected equally well by hemodialysis against either acetate or bicarbonate. This acidic pHi may be correlated with the increased concentration of ATP in erythrocytes in uremia, which is partly corrected by these two types of hemodialysis. Similarly, the significant decrease of spin-spin relaxation times in uremic patients is corrected by hemodialysis.

Acetates↗
PubMed1986

Inhibition of microtubule formation by uremic toxins: action mechanism and hypothesis about the active component.

We show in vitro inhibitory effect of a mixture of uremic toxins on tubulin 6S polymerization. It proves the existence of a direct interaction protein-toxin where micro-tubule associated proteins are not involved. A similar phenomenom could occur in uremic neuropathy. The action mechanism of this interaction is quite different from that of classical tubulin inhibitors: Vinca alcaloïdes and colchicine. Finally we hypothesize about the active molecule.

Animals↗
PubMed1986

A continuous hemofiltration system using sorbents for hemofiltrate regeneration.

Plasma ultrafiltrate obtained by glomerular filtration undergoes tubular modification which leads to the elimination of toxic substances, excess water and electrolytes, and consequently maintains homeostasis. Using normal urine and the substances it contains as a reference, we have developed a wearable device capable of replacing both the renal excretion function and maintaining fluid and electrolyte equilibrium in uremics within acceptable biological limits. Our device includes a hemofilter allowing continuous plasma ultrafiltration and sorbents obtained from a Redy sorbent cartridge to treat 85% of the ultrafiltrate, whereas 15% of this UF is rejected untreated. After calculating the quantity of ultrafiltrate (about 13 l) containing an amount of waste products of metabolism equivalent to 24-h urine elimination, we determined in vitro the amount of sorbent required to eliminate these waste products from the ultrafiltrate (e.g., 20 g of urea/day) and we have evaluated the quantities of other substances which must be replaced using a tailored diet. This extra-corporeal detoxification process was used in a uremic patient who had been on traditional hemodialysis for the past two years. The continuous treatment permitted maintenance of fluid and electrolyte equilibrium at the desired level and allowed rapid improvement of patient clinical status: elimination uf nausea, vomiting, diarrhea and edema, which had previously reappeared during the interdialytic periods, as well as a rapid decrease in heart size as ascites disappeared. In addition, the patient regained sexual drive and the ability to have an erection. In conclusion, traditional hemodialysis and hemofiltration techniques allow intermittent elimination of products retained by the body and reestablish nearly normal fluid and electrolyte balance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1986

Intra-erythrocytic sodium in uremic patients, as determined by "high-resolution" 23Na nuclear magnetic resonance.

The use of 23Na nuclear magnetic resonance with aqueous shift reagent has made it possible to determine intracellular sodium concentrations in living erythrocytes. We applied this technique to samples from 16 healthy subjects and 41 uremic patients. The results seem to show distinct populations among the latter. Classically, two different relaxation times are obtained for intracellular sodium in biological media, according to relaxation NMR theory. Some patients, however, exhibit abnormal results that cannot be accounted for by this theory.

Adult↗
PubMed1985

Action on mitochondrial calcium metabolism of an ionophorous compound isolated from uremic plasma or normal urine.

An ionophorous compound that is one of the uremic middle molecules is able to inhibit the mitochondrial storage of calcium. Its active concentration is equivalent to that found in uremic plasma. This result can explain the diminution of phosphate calcium granules observed in mitochondria from uremic children. Moreover, this phenomenon may be involved in the calcium pool decrease observed in chronic renal insufficiency.

Animals↗
PubMed1985

Dialysate sodium control during modeling in hemodialysis.

Dialysate sodium (Na+) modeling in hemodialysis requires precise individual adjustment and control of Na+ dialysate concentration. In practice, variations of Na+ concentration can be important and can affect the accuracy of Na+ modeling. Variations relate mainly to the low accuracy of dialysate concentrate (+/- 2.5% for Na+ is tolerated by the European Pharmacopeias), purity of hemodialysis water (2.17 mEq/L is the limit fixed by the French Pharmacopeia), and precision of the proportioning delivery systems for hemodialysis bath preparation. To minimize these difficulties, this study focused on the following points: (a) Na+ concentration is maintained constant (133 mEq/L) in the dialysate manufacturing unit. In 1982, 268 dialysate preparations (177,000 L) were made, and the mean value for Na+ concentration was 133.1 +/- 0.3 mEq/L with a probability of 99.9%. (b) The purity of the water, especially for Na+, Ca2+, and K+, is controlled for two times a day. (c) The accuracy of the proportioning delivery system is controlled by two conductivity monitors, and the variation of Na+ concentration around 133 mEq/L is smaller than +/- 0.5%. As the composition of the basic dialyzing fluid remains constant before adaptation, conductivity values reflect exactly Na+ variation, and are not affected by variations of other elements (K+, Ca2+, Mg2+) that may occur when modification of the dialysate is used for Na+ modeling. (d) Na+ dialysate concentration is adapted for each patient's need by a bedside monitor with sterile Na+ solutions (5 mol/L).(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1985

A compound from uremic plasma and from normal urine isolated by liquid chromatography and identified by nuclear magnetic resonance.

A compound present in normal urine and in ultrafiltrates of uremic plasma in the fraction of so-called "uremic middle molecules" was isolated by liquid chromatography. Preliminary studies, including amino acid analysis, characterization of uronic acids, and ultraviolet spectroscopy, show that the molecule contains glycine, a uronic acid, and an aromatic ring. Characterization by 1H and 13C nuclear magnetic resonance spectrometry shows conclusively that this compound is a double conjugate of glucuronidate--o-hydroxyhippuric acid, which has been previously described by Zimmerman et al., using quite different techniques of isolation and identification (Clin Nephrol 14: 107, 1980; FEBS Lett 129: 237, 1981).

Chemical Phenomena↗
PubMed1985

Identification by nuclear magnetic resonance and mass spectrometry of a glucuronic acid conjugate of o-hydroxybenzoic acid in normal urine and uremic plasma.

An endogenous compound (included in the fraction of uremic toxins often called the "uremic middle molecules") was separated from plasma of uremic patients and urine from normal persons. As elucidated by mass spectrometry, enzymatic hydrolysis, and 1H, 13C nuclear magnetic resonance, it appears to be a conjugate of o-hydroxybenzoic acid with glucuronic acid. Its presence in urine of healthy subjects indicates its physiological character.

Adult↗