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Biomedical subjects

N Ronda

Publications and source records attributed to N Ronda.

27 records · Page 2Linked to original sources
PubMed1989

Cell metabolism in patients undergoing major valvular heart surgery: relationship with intra and postoperative hemodynamics, oxygen transport, and oxygen utilization patterns.

The relationships between cell metabolism and both hemodynamics and oxygen transport/utilization (VO2/DO2) pattern were evaluated intra and postoperatively in eight patients undergoing major valvular heart surgery with the aid of moderately hypothermic cardiopulmonary bypass (CPB). Quadriceps femoris specimens were obtained by the needle biopsy technique for muscle ATP, ADP, AMP, phosphocreatine (PCr), creatine and lactate determination at anesthesia induction, after CPB, as well as in the ICU 18 h after surgery. Moreover, hemodynamic variables, oxygen transport and utilization indices, and plasma lactate were measured at the same intervals and throughout the CPB period. After CPB, muscle ATP and PCr contents were reduced (p less than .05) as compared to those of both pre-CPB patients and healthy control subjects; muscle and plasma lactate levels were increased (p less than .05). Mean VO2 and DO2 values measured during CPB significantly decreased (p less than .05), but VO2 reduction was proportionally greater than that of DO2 (-62% vs. -41%). No correlation was found between VO2 and DO2 at that time, but a significant relationship (p less than .05) was found at the end of CPB. A further decrease in muscle ATP and PCr levels was measured in the ICU, as muscle and plasma lactate levels were still elevated. At that time, VO2 and DO2 were not significantly different from pre-CPB values, but were significantly (p less than .05) correlated with each other.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1988

Cell metabolism response to cardiopulmonary bypass in patients undergoing aorto-coronary grafting.

The main parameters of muscle acid-base, water and energy metabolism were studied in ten patients undergoing low-flux (1.5 l/min/m2), low-pressure (40 to 60 mmHg) hypothermic (26 degrees C) cardiopulmonary bypass (CPB) for aortocoronary grafting; absolute gas exchange and haemodynamic data were also measured throughout the entire CPB period. At the end of CPB a substantial preservation of water and energy metabolic indexes was found; a condition of extracellular metabolic acidosis was apparently sustained by muscle cell anaerobic glycolysis enhancement with a consequent increase of both muscle and plasma lactate content. Subnormal cell phosphocreatine levels as well as reduced bicarbonate buffer stores and decreased intracellular pH, were detected. Direct limiting effects of hypothermia on tissue O2 delivery and muscle oxidative metabolism as well as vasoconstriction and arteriovenous shunting associated with CPB procedures are likely to be involved in the above mentioned alterations of cell metabolism.

Acid-Base Equilibrium↗
PubMed1987

Skeletal muscle energetics, acid-base equilibrium and lactate metabolism in patients with severe hypercapnia and hypoxemia.

Quadriceps femoris muscle needle biopsies were performed in ten patients with chronic obstructive pulmonary disease and acute respiratory failure and in ten age- and sex-matched healthy control subjects. The main indices of skeletal muscle cell energy metabolism, intracellular acid-base equilibrium and lactate metabolism were evaluated. Reduced ATP and phosphocreatine content, intracellular acidosis related to hypercapnia, increased muscle lactate without alterations of the muscle lactate concentration gradient were observed in the skeletal muscle of the hypercapnic-hypoxemic COPD patients studied, in which group no correlation was found between hypoxia and energy or lactate metabolism parameters. These results suggest that an overall derangement of cell energy metabolism and acid-base equilibrium is present in severely hypercapnic-hypoxemic chronic obstructive pulmonary disease and that in this condition skeletal muscle seems to metabolize anaerobically-even though, in addition to hypoxia, other factors interfering with both cell energy and lactate metabolism are likely to be present.

Acid-Base Equilibrium↗
PubMed1986

Muscle energy metabolism in uremia.

Energy-rich phosphagens were measured in 11 patients with end-stage chronic renal failure and 11 nonuremic subjects. A significant decrease of ATP, phosphocreatine, total adenine nucleotides, lactate, and energy charge was found. The present results can be referred both to glycolytic sequence disturbances and to the lack of substrates characteristic of uremia.

Adenine Nucleotides↗
PubMed1986

Uremic acidosis and intracellular buffering.

Skeletal muscle biopsies were performed in 16 controls and 15 non-dialysed end-stage chronic renal failure (CRF) patients presenting untreated metabolic acidosis. Intracellular bicarbonate, pH, water compartments and electrolytes were determined. In 8 of 15 patients muscle ATP and lactate were measured. Intracellular bicarbonate (HCO3i) and pH (pHi) were obtained by means of muscle total carbon dioxide method: a significant (p less than 0.001) reduction in both intracellular acid--base indexes was found in all patients (pHi 6.82 +/- 13 vs. 7.04 +/- 0.05; HCO3i 6.28 +/- 2.07 vs. 11.86 +/- 0.87). Total muscle as well as extracellular water was increased. Muscle sodium and chloride contents were also increased, while no change in potassium and magnesium was detected. A significant decrease of both muscle ATP and lactate was found. The data lead to the conclusion that chronic retention of acids in CRF results in a depletion of the muscle buffer pool and consequently in intracellular acidosis: the latter could be the main cause of the cell energy metabolism derangement described in uremia.

Acidosis↗
PubMedDate not supplied

Spectrum of autoimmune responses in systemic vasculitis.

Growing evidence supports the inclusion of primary forms of systemic vasculitis within the category of autoimmune diseases. Thus their association with a family of autoantibodies, related to their specificity or neutrophil cytoplasm antigens, has been identified and the role these autoantibodies play in pathogenesis is now being explored. Different members of the autoantibody family have now been characterised in terms of their molecular specificity and the isotype of immunoglobulin of which they are composed. These properties may be a useful adjunct in the classification of systemic vasculitis (see table I). It is the purpose of this review to put a perspective on the specificity and pathogenicity of autoantibodies found in patients with systemic vasculitis and to outline new strategies for the treatment of these conditions, based on the involvement of autoimmune mechanisms in the development of these disorders.

Antibodies, Antineutrophil Cytoplasmic↗
PubMedDate not supplied

[Adherence to dietetic treatment, the nutritional metabolic status and the progression of chronic kidney failure].

Effects of two protein restricted diets on dietary compliance, nutritional and metabolic state, and progression of chronic renal failure (CRF) were investigated. Twenty-one patients with CRF were randomly assigned to either a conventional low protein diet (0.6 g of protein/kg b.w./day) or to a very low protein diet, providing 0.4 g of protein/kg b.w./day, supplemented with a mixture of essential amino acids which contained HIS, TYR and a high proportion of branched chain amino acids. Nutrition, assessed by body weight, anthropometry, serum protein levels and nitrogen balance studies, was maintained in all patients. Some metabolic abnormalities of CRF (i.e., secondary hyperparathyroidism, glucose intolerance) improved in both groups. The supplemented diet provided better adherence to protein prescription, corrected the depletion of VAL and LEU in muscle and was more effective than conventional diet in slowing the rate of progression of CFR.

Adult↗