Disturbances of purine nucleotide metabolism in uremia.

The increased concentration of adenosine triphosphate (ATP) in erythrocytes from patients with chronic renal failure (CRF) has been observed in many studies but the mechanism leading to these abnormalities still is controversial. It is believed that hyperphosphatemia and metabolic acidosis triggering enhanced reutilization of purine bases are the factors responsible for changes in erythrocyte nucleotide concentration. During the past decade we have performed several studies.

Accelerated degradation of adenine nucleotide in erythrocytes of patients with chronic renal failure.

Recently, we have shown that erythrocytes obtained from patients with chronic renal failure (CRF) exhibited an increased rate of ATP formation from adenine as a substrate. Thus, we concluded that this process was in part responsible for the increase of adenine nucleotide concentration in uremic erythrocytes. There cannot be excluded however, that a decreased rate of adenylate degradation is an additional mechanism responsible for the elevated ATP concentration.

Increased rate of adenine incorporation into adenine nucleotide pool in erythrocytes of patients with chronic renal failure.

Background: Elevated purine nucleotide pool (mainly ATP) in erythrocytes of patients with chronic renal failure (CRF) is a known phenomenon, however the mechanism responsible for this abnormality is far from being clear. We hypothesize that the increased rate of adenine incorporation into adenine nucleotide pool is responsible for the elevated level of ATP in uremic erythrocytes.

Methods: In chronically uremic patients we evaluated using HPLC technique: (a) plasma adenine concentration; (b) the rate of adenine incorporation into adenine nucleotide pool in uremic erythrocytes.

Catabolism of the methyl derivatives of adenosine and cytidine in staphylococci.

Products of 1-methyladenosine, 2'-O-methyladenosine, 2'-O-methylcytidine, and 5-methylcytidine catabolism by resting cells of Staphylococcus aureus and Staphylococcus intermedius were chromatographically separated. The methyl group in 1-methyladenosine protected the adenosine derivative from deamination by S. intermedius but it did not protect N-glycosidic bond from cleavage by S.

[Deamination of adenine and adenosine in staphylococci].

Deaminations of adenine and adenosine by pattern strains of 24 staphylococcal species, were tested. During 3 hours of incubation of the suspensions of 8 staphylococci with adenine the liberation of ammonia occurred. The same staphylococci accumulated ammonia in the incubation medium with adenosine.

[The levels of adenine nucleotides and hypoxanthine in blood of patients on long-term hemodialysis using dialysis fluid containing acetate or bicarbonate].

Intraerythrocyte adenine nucleotides concentration reflects energy balance of red cells and plays pivotal role in their function. In hemodialysed patients both ATP and ADP concentration in red cells was higher than in controls, p < 0.001 and p < 0.

Erythrocyte nucleotides and blood hypoxanthine in patients with uremia evaluated immediately and 24 hours after hemodialysis.

Using high-performance liquid chromatography, concentrations of erythrocyte adenine nucleotides and hypoxanthine were evaluated in patients undergoing regular acetate hemodialysis before dialysis, immediately following dialysis, and 24 hr after. It was shown that adenosine triphosphate concentration was maintained consistently high, not only just after hemodialysis but also 24 hr later. There was also no difference in concentration of mono- and diphosphates of adenosine.

Diversity of adenine conversion in staphylococci.

The special position of Staphylococcus intermedius in comparison with Staphylococcus saprophyticus, Staphylococcus chromogenes, and Staphylococcus hyicus was shown by deamination of adenine to hypoxanthine. S. chromogenes and S.

[Concentration of adenine nucleotides in blood of predialysis patients with chronic renal failure].

Intraerythrocyte and blood level ATP concentration is increased in CRF. But little is known on the blood concentration of ADP and AMP in CRF. HPLC was applied to evaluate the ATP, ADP, AMP concentration in blood of 25 CRF patients, with serum creatinine from 2.

High performance liquid chromatographic determination of methacrylate in blood serum.

Methacrylic acid is a hydrolytic breakdown product of methylmethacrylate which is widely used in orthopaedic surgery, dentistry and in the chemical industry for fabrication of acrylic resins. Information on the toxicity of methacrylic acid and its metabolism is limited. To facilitate studies in this field we developed a liquid chromatographic procedure allowing determination of methacrylate in blood serum.

A novel route of ATP synthesis.

Incorporation of the adenine moiety of 2'-deoxyadenosine (dAdo) into ATP, consistently observed in human erythrocytes, is a phenomenon which cannot be explained by the operation of any known pathway. We reported previously that this effect was not observed in adenine phosphoribosyltransferase-deficient erythrocytes showing that adenine must be an obligatory intermediate. However, generation of adenine from dAdo was difficult to reconcile with the operation of any known process in human cells, and involvement of S-adenosylhomocysteine hydrolase (SAH-hydrolase) was postulated.

Degradation of adenine nucleotides in the erythrocytes of patients with chronic renal failure.

In chronic renal failure AMP-deaminase operates in the erythrocytes at a much higher velocity than in healthy subjects, with a simultaneous shift from the AMP-adenine-inosine-hypoxanthine pathway (55% and 19%, respectively) to the pathway initiated by AMP-deaminase (45% and 81%, respectively).