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Biomedical subjects

M Marangella

Publications and source records attributed to M Marangella.

At least 55 records · Page 3Linked to original sources
PubMed1991

Plasma profiles and removal rates of inorganic sulphate, and their influence on serum ionized calcium, in patients on maintenance haemodialysis.

1. Regular dialysis treatment is reported to remove inorganic sulphate, but not to restore its level to normal. To evaluate the adequacy of modern dialysis techniques in maintaining the sulphate balance, intra- and interdialysis plasma profiles and removal rates of sulphate were studied in 20 stable patients on maintenance haemodialysis. The influence of sulphate levels on the distribution of calcium-complex species was also investigated. 2. Sulphate was determined by ion-exchange chromatography of both serum ultrafiltrates, taken at the start of, during, at the end of, and at 24 h and 48 h after a dialysis session, and whole diffusate collections. Dialyser clearances of sulphate were assessed by two independent procedures and compared with those of urea and creatinine, on two different methods of dialysis, i.e. traditional haemodialysis with Cuprophan hollow fibre filters, and haemodiafiltration with high-flux Polysulphone or polyacrylonitrile dialysers. Concentrations of the main serum ions were determined before and after dialysis and used to solve a multiple mass balance equation system by which concentrations of the calcium-complex species were calculated. 3. Before dialysis, sulphate levels were eight times those determined in 17 control subjects and remained higher than normal at the end of dialysis. These changes were independent of the dialysis procedure. There was a close correlation between serum levels of sulphate and creatinine. Dialyser clearances of sulphate were comparable with those of creatinine, but lower than those of urea. Clearances of all solutes were higher on haemodiafiltration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Serum calcium oxalate saturation in patients on maintenance haemodialysis for primary hyperoxaluria or oxalosis-unrelated renal diseases.

1. The serum oxalate concentration rises in chronic renal failure and it is only partially eliminated by regular dialysis treatment. However, the recent literature is not conclusive on whether progressive oxalate retention and secondary oxalosis should be expected in patients on regular dialysis treatment. 2. To further investigate this, we have estimated the state of saturation with respect to calcium oxalate monohydrate in plasma ultrafiltrates from 28 patients on maintenance haemodialysis and eight healthy control subjects, matched for sex and age. Five patients had type I primary hyperoxaluria and histologically proven oxalosis, whereas 23 had oxalosis-unrelated renal diseases. Dialysis efficiency was quantified as the KdTd/V of urea. Samples were obtained from each patient before, immediately after and 48 h after a dialysis session. Fasting samples were obtained from the control subjects. Oxalate was determined in both plasma ultrafiltrates and the whole dialysate by ion-exchange chromatography, after a non-delayed and [14C]oxalate-recovery-controlled procedure. The state of saturation with calcium oxalate monohydrate was estimated by means of a computer system which solved the interactions among 45 complex species. 3. The fasting plasma oxalate concentration (means +/- SD) in ultrafiltrates from healthy subjects was 3.8 +/- 1.5 (range 1.4-5.8) mumol/l, and the state of saturation with calcium oxalate monohydrate was 0.096 +/- 0.04.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Renal handling of citrate in chronic renal insufficiency.

Citrate is a relevant component of the inhibitory potential of the urine environment. Its excretion and renal handling have been widely studied in subjects with normal renal function, but little is known about changes induced by chronic renal insufficiency. We have investigated renal handling of citrate in 50 patients with different degrees of renal insufficiency as compared to 30 healthy subjects with normal renal function. Among patients 34 were defined as having mild renal insufficiency based on a GFR of 80 through 40 ml/min/1.73 m2 BSA, while 16 had moderate-to-severe renal failure, defined by a GFR ranging from 40 to 20 ml/min/1.73 m2 BSA. Serum citrate increased in mild renal insufficiency, while it tended to be restored to normal values at more advanced renal failure. There was a stepwise decrease in the filtered load of citrate as GFR decreased, while its renal clearance was significantly reduced only at higher degrees of renal failure. This behavior was due to an increase in the fractional excretion of citrate which was inversely related to the decrease in GFR (p = 0.015). These data suggest that serum citrate levels and excretion are governed by renal mechanisms at mild degrees of renal insufficiency; in these conditions citrate is shown to behave conformly to other poorly reabsorbable anions such as sulfate. At more advanced renal failure the ensuing metabolic acidosis plays a crucial role as a regulatory factor of both serum concentration and renal handling of citrate, by increasing cellular uptake and metabolism as well as tubular reabsorption of this anion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Imbalance↗
PubMed1991

Ion-chromatographic determination of L-tartrate in urine samples.

We propose using ion chromatography to determine tartrate concentration in urine. A 100-microL sample of urine is diluted and injected into the chromatograph. Tartrate is eluted within 11.5 min as a distinct and well-resolved peak. The sensitivity of the standard procedure (signal-to-noise ratio, 3/1) is 30 mumol/L. The intra-run and interrun coefficients of variation are 2.5% and 4.1%, respectively. Mean analytical recovery of known amounts of added tartrate ranges between 94.2% and 104.0%. We investigated the specificity of the procedure by analyzing urine containing added dicarboxylic acids structurally related to tartrate. The reliability of the procedure makes it suitable for investigating tartrate metabolism, e.g., the potential role of tartrate as an inhibitor of crystallization in calcium nephrolithiasis.

Adult↗
PubMed1990

Ion chromatographic determination of plasma oxalate in healthy subjects, in patients with chronic renal failure and in cases of hyperoxaluric syndromes.

An ion chromatographic procedure for the determination of plasma oxalate is proposed, in which the ultrafiltered sample is injected into an ion-chromatographic system. Sample processing appears effective in avoiding spontaneous oxalogenesis. Sensitivity (down to 1.0 mumol/l) allows determinations in normal and pathological samples; recoveries from plasma ultrafiltration are 94.6 +/- 11.7%. Protein binding was investigated and precautions to improve recoveries from plasma ultrafiltration are proposed. The technique is simple to perform from healthy controls averaged 6.75 +/- 2.62 mumols/l (mean +/- S.D. n = 18); samples from patients with primary hyperoxaluria and chronic renal failure undergoing regular dialysis were also analysed and some of the data obtained are reported and discussed.

Adult↗
PubMed1990

Primary oxalosis mimicking hyperparathyroidism diagnosed after long-term hemodialysis.

Primary oxalosis is a rare inborn error of oxalate metabolism. Most cases are discovered in children, but occasionally symptoms begin later in life. Since early deaths in the past were from renal failure, prolonged survival obtained with chronic dialysis allows oxalosis to develop. This paper presents a 38-year-old man with an atypical history of type-I primary hyperoxaluria, not diagnosed until after 5 years of dialysis. Bone biopsy was performed because the biochemical and radiologic features did not seem consistent with a putative diagnosis of secondary hyperparathyroidism. This case emphasizes the clinical heterogeneity of this disorder, and the need for its considerations in the spectrum of dialysis-related bone diseases. It also stresses that bone oxalosis may mimic hyperparathyroidism, especially radiologically. Differential diagnosis is therefore mandatory.

Adult↗
PubMed1990

Prevalence of chronic renal insufficiency in the course of idiopathic recurrent calcium stone disease: risk factors and patterns of progression.

The occurrence of chronic renal insufficiency was investigated in 171 patients with severe idiopathic calcium stone disease. Ninety healthy subjects matched for age and sex were used as controls. The patients were thereafter subclassified into two subgroups, assuming a GFR of 80 ml/min/1.73 m2 body surface area as a cut-off value: the normal GFR, 141 patients, and the impaired GFR, 30 patients. The normal GFR group included more males and the patients were younger both at onset and at presentation. In the impaired GFR group the disease lasted longer, but the overall stones and the stone recurrence rate were as high as those of the normal GFR patients. The single stone episodes were more severe in the former group as suggested by the occurrence of more surgery and complications. The GFR level was in part predicted by the age of patients; however, stone disease was shown to induce a clear-cut influence in accelerating the natural worsening of GFR with age. The onset of renal insufficiency causes multiple changes in renal pathophysiology, which result in a sharp decrease in the urine saturation with respect to calcium salts. These changes account for the decrease in the stone recurrence rate in the impaired GFR group. Thus, unless factors independent of or complicating the calcium stone disease supervene, the renal insufficiency of treated patients remains mild and relently progressive.

Adult↗
PubMed1990

Preventing ascorbate interference in ion-chromatographic determinations of urinary oxalate: four methods compared.

In an attempt to decrease ascorbate interference on the ion-chromatographic determination of urinary oxalate, we compared the effectiveness of four different methods for ascorbate elimination by analyzing a representative urine pool supplemented with successive ascorbate additions. Two of the methods--treatment with ferric ions or boric acid--have been described elsewhere; treatments with nitrites or ascorbate oxidase (EC 1.10.3.3) are investigated here as possible alternatives. Consideration of the main features, advantages, and drawbacks of the four procedures leads us to conclude that boric acid dilution is a good routine method and that pre-incubation with ascorbate oxidase reliably prevents ascorbate interference in assays of urinary oxalate.

Adult↗
PubMed1989

Derivatization and high-performance liquid chromatographic determination of urinary glycolic acid.

A high-performance liquid chromatographic method for the determination of urinary glycolic acid is proposed, based on pre-column derivatization with phenylhydrazine coupled with the enzymatic oxidation of glycolate to glyoxylate. The phenylhydrazone formed is separated by liquid chromatography and detected at 324 nm. The minimum detectable concentration of glycolate was 10.0 mumol/l. The recovery of glycolate added to urine averaged 96.1%. The day-to-day coefficients of variation calculated by analysis of two urine samples with normal and high glycolate contents were 4.6 and 7.5%, respectively. Results of analyses of urine samples from healthy persons, idiopathic calcium stone formers and Type I primary hyperoxaluria patients are reported.

Chromatography, High Pressure Liquid↗
PubMed1989

CAPD with an amino acid dialysis solution: a long-term, cross-over study.

This prospective cross-over study was undertaken to evaluate the safety and efficacy of a 1% amino acid dialysis solution on the nutritional and metabolic changes, plasma amino acid profiles and peritoneal membrane function of patients on CAPD. Six CAPD patients had one exchange a day with two liters of this solution over a six month period. Every month there was a medical examination, anthropometric measurements and dietary inquiry were made, blood biochemistry tests were done. Every three months renal function, peritoneal function, aminograms of plasma and dialysate and nitrogen balance were determined. Data were compared with those obtained one month prior to and three months after withdrawal of amino acid administration. Nitrogen balance, which was negative (-1.3 g/day) became positive (+3.1 g/day). Patients who were already overweight increased in weight, both in fat and lean mass. Plasma cholesterol and triglycerides significantly decreased and the amino acid profile moved towards normal; plasma urea levels increased and pH and bicarbonate decreased slightly but significantly (P less than 0.05). Plasma protein concentrations did not change. All the above parameters turned towards basal values when amino acids were discontinued. We conclude that amino acids can be used as osmotic agents for CAPD since they do not cause toxic effects or impair peritoneal membrane function. Moreover, they can help the nutritional status, provided that an increase in weight is prevented and the slight worsening of systemic acidosis is corrected.

Amino Acids↗
PubMed1989

Effect of animal and vegetable protein intake on oxalate excretion in idiopathic calcium stone disease.

Oxalate excretion was measured in healthy subjects and idiopathic calcium stone-formers on dietary regimens which differed in the type and amount of protein allowed; 24-h urine collections were obtained from 41 practising vegetarians and 40 normal persons on a free, mixed, "mediterranean" diet. Twenty idiopathic calcium stone-formers were also studied while on two low calcium, low oxalate diets which differed in that animal protein was high in one and restricted in the other. Vegetarians had higher urinary oxalate levels than controls and although the calcium levels were markedly lower, urinary saturation with calcium/oxalate was significantly higher. This mild hypercalciuria was interpreted as being secondary to both a higher intake and increased fractional intestinal absorption of oxalate. Changing calcium stone-formers from a high to a low animal protein intake produced a significant decrease in calcium excretion but there was no variation in urinary oxalate. As a result, the decrease in calcium oxalate saturation was only marginal and not significant. It was concluded that dietary animal protein has a minimal effect on oxalate excretion. Mild hyperoxaluria of idiopathic calcium stone disease is likely to be intestinal in origin. Calcium stone-formers should be advised to avoid an excess of animal protein but the risks of a vegetable-rich diet should also be borne in mind.

Adult↗
PubMed1988

High-performance liquid chromatographic determination of glyoxylic acid in urine.

A high-performance liquid chromatographic (HPLC) method for the determination of urinary glyoxylic acid is proposed. The system is based on the precolumn derivatization of alpha-keto acids by means of phenylhydrazine, separation of the phenylhydrazone formed by HPLC and spectrophotometric detection at 324 nm. The method is precise and allows the determination of 0.5 mumol/l glyoxylate. The poor stability of glyoxylate under all conventional preservation conditions requires the analysis to be carried out as soon as possible after urine collection. Results of determinations on urine samples from healthy controls and from patients with idiopathic calcium stone disease and type I primary hyperoxaluria are reported.

Chromatography, High Pressure Liquid↗
PubMed1987

High-performance liquid chromatographic determination of glyoxylic acid and other carbonyl compounds in urine.

A high-performance liquid chromatographic method for the determination of carbonyl compounds, namely aldehydes, ketones and keto acids in urine, has been developed. Pre-column derivatization with 2,4-dinitrophenylhydrazine offers sufficient sensitivity for the determination of glyoxylic acid in urine with a detection limit of 0.5 mg/l. The separation is performed on a C18 10-micron column and with an acetonitrile-aqueous buffer mobile phase, which also allows the resolution of the syn and anti geometric isomers. Matrix effects, precision, accuracy, limits of detection and structural selectivity of the method are discussed.

Aldehydes↗
PubMed1985

Urine saturation with calcium salts in normal subjects and idiopathic calcium stone-formers estimated by an improved computer model system.

The state of saturation of urine with calcium salts has been estimated by means of a computer model system whose accuracy has been improved by the use of stability constants of 31 complexes which were re-determined at 37 degrees C and at the actual ionic strength of urine. The experimental determination of the concentration solubility products of calcium oxalate monohydrate (CaOx) and of calcium hydrogen phosphate dihydrate (bsh) allows an expression of the saturation degree as free concentration product ratio beta CaOx and beta bsh. Morning urine samples from 50 healthy controls and 50 idiopathic calcium stone-formers and 24 h urines from 40 normal subjects and 192 stone-formers, taking normal diet were investigated by this technique. From our results urine supersaturation with calcium oxalate salts seems to play an important role in calcium stone disease. Hypercalciuria and hyperoxaluria seem to be the main pathological features in this regard. The data concerning beta bsh values have not confirmed previous reports in which this parameter was found to be increased in stone-formers.

Calcium↗