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Biomedical subjects

G Barsotti

Publications and source records attributed to G Barsotti.

105 records · Page 6Linked to original sources
PubMed1975

Uremic intoxication.

The toxic effects of metabolites that are known to accumulate in renal failure are described and the role that they may play in causing uremic symptoms is considered. The opinion of the Authors is that all they are likely to take a lesser or greater part in uremic intoxication. Methylguanidine seems to be very important in this context while for some others (like amines) nothing can be stated for studies on their chronic toxicity are lacking. The hypothesis is also considered of the accumulation of unidentified toxic metabolites with a middle molecular weight. It is stated, as to this problem, that the clinical evidence apparently supporting univocally their existence, is instead also consistent with the hypothesis of toxins (like methylguanidine) having a preferential distribution in the intracellular fluid compartment.

Amines↗
PubMed1975

Removal by dialysis of methylguanidine from body fluids.

The dialysis clearance of methylguanidine (MG) was found to be lower 'in vivo' than 'in vitro' and to decrease during a haemodialysis. Its protein binding, which rises as the plasma pH rises during haemodialysis, accounts for its dialysis behaviour. The low dialysis clearance of MG 'in vivo' explains why the post dialysis percentage decrease in its plasma levels is lower than that of urea (U) and of creatinine (CR). The slow transfer of MG from tissue during dialysis, shown by direct measurements on plasma and muscle tissue of anuric dogs, accounts for its high plasma rebound level after haemodialysis. Rebounds after peritoneal dialysis were lower and the plasma MG levels 12 hr after the termination of the two dialysis procedures were not different. The dialytic behaviour of MG is different from that of U and of CR which have similar molecular weights and the conclusions drawn from the behaviour of the latter two metabolites cannot be applied to MG. On the contrary, the removal of MG from body fluids of uraemic patients by dialysis is equal with peritoneal dialysis and with the various haemodialysis schedules that ensure good clinical results, while leaving plasma U and CR concentrations in a high range.

Animals↗
PubMedDate not supplied

Safety and efficacy anticoagulation in extracorporeal hemodialysis by simultaneous administration of low-dose prostacyclin and low molecular weight heparin.

BACKGROUND: The aim of this work is to describe an approach allowing extracorporeal hemodialysis (HD) with administration of low molecular weight heparin (LMWH) and to compare the dialyzer efficiency of this approach versus infractionated heparin (UFH) used alone. METHODS: Low molecular weight heparin (Nadroparin, molecular weight 4500 d) administered in a single injection (dose 3075 IU AXa) plus prostacyclin (Epoprostenol sodium salt, molecular weight 375 d) by continuous infusion (3 ng/kg/min) have been used as anticoagulants during hemodialysis in 8 patients. In comparison, standard continuous heparinization by unfractionated heparin was used. Hemodialysis efficiency (dialyzer clearance for urea, creatinine, uric acid and phosphate), coagulation (activated partial thromboplastin time, antithrombin III, fibrinogen platelet count, prothrombin time) and hemodynamic parameters (blood arterial pressure and heart rate) were also evaluated during dialysis. RESULTS AND CONCLUSIONS: Simultaneous infusion of low molecular weight heparin plus prostacyclin allowed safe and effective anticoagulation without affecting hemodialysis efficiency.

Adult↗
PubMedDate not supplied

Color-Doppler in the imaging work-up of primary hyperparathyroidism.

Primary hyperparathyroidism (PHP) is a rare disease that must be suspected in all the cases of recurrent calcium nephrolithiasis, and that may be totally corrected by surgery. The imaging techniques permit to locate the hyperplastic gland or adenoma before intervention, but their usefulness in patients without a history of previous neck surgery is still debated. Several imaging techniques have been proposed with the aim of locating parathyroid hyperfunctioning glands, including high resolution sonography (US) with color-Doppler (CD), scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI). We report here a case of recurrent calcium oxalate nephrolithiasis sustained by PHP, which demonstrates how US coupled with CD and echocontrast enhancement is useful in the preoperative location of parathyroid glands. US is the first choice technique in the evaluation of PHP because it is less expensive and useful in detailing lesions of the neck when carried out by a skilled operator. CD should be regarded as a useful complement of US enhancing its sensitivity (80 vs 90%) especially in the cases of associated thyroid gland diseases. Tc-99m SESTAMIBI scintigraphy coupled with MRI is mandatory in high risk surgical patients, namely in those undergoing repeated neck surgery. In conclusion, considering that surgeon must explore all the four parathyroid glands (because of the possibility of multiple adenomas or hyperplasia) a well definite location of the adenomatous lesion may reduce the risks and the time of intervention, and allow the use of alternative procedures, such as videoscopic surgery. On this view and in terms of economy, only US and CD coupled with Tc-99 SESTAMIBI scintigraphy should be considered before surgery.

Adenoma↗
PubMedDate not supplied

[Dialysis of methylguanidine and hypothesis on the middle molecules].

The formulation of "Methilguanidine (MG) hypothesis" started from previous researches that showed that uramic symptoms in dogs intoxicated by MG were present. Being a low molecular weight molecule, MG as Urea (U) and Creatine (CR), should not be considered an "uraemic toxin" according with the "middle molecules hipothesis". We have studied, during peritoneal and various hemodialysis schedules, MG "in vivo" and "in vitro" clearance, post-dialytic rebound, plasmaaproteins binding, intra and extracellular distribution. "In vitro" MG clearance is intermediate between U and CR, but "in vivo" MG clearance is lower than U and CR: what is explained by MG prevalent intracellular distribution and by the increasing plasm proteins binding during hemodialysis alkalinisation. 12 hours after high efficiency dialysis MG has an higher rebound than U and CR because of the slow and constant MG flow from intracellular fluid to plasma. On the other hand a continuous equilibrium between intra extracellular MG happens during the longer and less efficient peritoneal dialysis: MG plasma level 12 hours after peritoneal dialysis is the same that after high efficiency hemodialysis; on the contrary U and CR plasma levels are higher after peritoneal than after hemodialysis. In spite of the low molecular weight MG dialysis is different than U and CR. Good clinical condition of patients on peritoneal and low-flow-dialysis which represented the basis of the ""MG hypothesis": infact MG removal is the same during peritoneal and hemodialysis.

Animals↗
PubMedDate not supplied

[Historical Archives of Italian Nephrology: Sergio Giovannetti (1924-2000): A distinguished representative of the School of Pisa].

Sergio Giovannetti (1924-2000) was one the most outstanding representatives of the Pisa School, which developed in the middle of the '60s thanks to the charismatic action of Gabriele Monasterio (1903-1972). Giovannetti's main contributions to the development of nephrology were as follows: - With Quirino Maggiore he outlined a low-protein diet of high biological value--adopted worldwide for many years--for those patients affected by advanced chronic renal failure. - He investigated the role and importance of uremic toxins (particularly methylguanidine) in renal failure. - He outlined a low-protein diet with low phosphorus supply, supplemented with essential amino acids and ketoanalogues, aiming at reducing the progression of chronic renal failure. Finally Giovannetti helped nephrology working as co-editor (together with Geoffrey M. Berlyne), of the journal 'Nephron' for 27 years. He was also the organizer of the 24 th Congress of the Italian Society of Nephrology in Pisa, in 1993.

History, 20th Century↗