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Biomedical subjects

A Conte

Publications and source records attributed to A Conte.

At least 91 records · Page 5Linked to original sources
PubMed1991

The origin and causes of struvite stones.

The aim of this paper is to evaluate the possible causes of the origin of "infection stones". The main differences between the ordinary biochemical parameters of a group of patients with this type of stones was analyzed and compared with a group of oxalocalcic stone-formers and with a group of healthy subjects. The importance of persistent basic urinary pH values is pointed out as possible origin of "infection stones" in some instances. The main urinary citrate concentration in patients with "infection stones" was significantly lower than in healthy subjects, this being an important factor that favours this kind of stone formation.

Calcium Oxalate↗
PubMed1991

Metabolic fate of exogenous chondroitin sulfate in man.

Chondroitin sulfate is administered as a drug to man by intravenous, intramuscular or oral route. However, few data are available on the metabolic fate of exogenous chondroitin sulfate in man. After intravenous administration of 0.5 g of chondroitin sulfate to healthy volunteers, the plasma level decreases according to a two-compartmental open model. The half-lives of distribution and elimination are 25.5 +/- 6.6 and 281 +/- 32 min, respectively. The volumes of central and tissue compartments are 6.0 +/- 1.0 and 22.9 +/- 7.7 l, respectively. More than 50% of the administered chondroitin sulfate is excreted with urine during the first 24 h as high and low molecular weight derivatives. After oral administration of 3 g of chondroitin sulfate to 12 healthy volunteers, a main peak (11.4 +/- 3.7 micrograms/ml) preceded by a lower peak is observed after 190 +/- 21 min. The elimination half-life is 363 +/- 109 min. The absolute bioavailability following oral administration calculated from AUC of plasma concentration is 13.2%. A peak of oligo- and polysaccharides with a molecular weight lower than 5000 Daltons derived from partial digestion of exogenous chondroitin sulfate is also present in plasma. These observations indicate that the metabolic fate of exogenous chondroitin sulfate is similar in man and in experimental animals.

Administration, Oral↗
PubMed1991

Effect of propionyl carnitine on cardiac energy metabolism evaluated by the release of purine catabolites.

The assessment of purine release in perfusion fluid is a new method (Zucchi et al.) which allows a continuous evaluation of energy metabolism in isolated perfused rat heart. Purine release in fact is related to the imbalance between ATP formed and utilized in myocytes. With this method we have investigated the effect of propionyl carnitine, carnitine and propionate on the working heart. The presence of millimolar concentrations of propionyl carnitine decreases purine release and improves cardiac performance as measured by cardiac output and double product (product of heart rate and aortic systolic pressure). Propionate has no effect, while carnitine slightly decreases purine release. The property shown by propionyl carnitine in decreasing the imbalance between ATP production and utilization and in improving cardiac performance is due to its ability to improve the energy metabolism of cardiomyocytes. This compound supplies oxidizable substrates and intermediates to the tricarboxylic acid cycle. In the presence of propionyl carnitine the myocardium therefore responds better to the sudden requirements of overwork and shows better functional efficiency for longer periods.

Adenosine Triphosphate↗
PubMed1991

Antidyslipaemic action and role of CoA in lipid metabolism of mitochondria and peroxisomes.

Our study has evaluated the effect of the parenteral administration of CoA on the pattern of haematic lipids and on palmitate oxidation in liver mitochondria and peroxisomes of rats made hyperlipaemic with a high fat diet with or without CoA. Lipid fractions, total cholesterol, triacylglycerols, total lipids and nonesterified fatty acids (NEFA) were determined in blood. Palmitate oxidation was determined in liver peroxisomes and mitochondria incubated in modified Krebs-Henseleit solution with 100 microM 1-14C palmitate in the presence and absence of some cofactors. Our results show that in rats fed with a high fat diet there was an increase of all lipid fractions. The increase of all lipid components was lower in animals treated with CoA. In liver peroxisomes of rats fed with high fat diet an increase in palmitate oxidation, that is higher when CoA is parenterally administered, was observed. In addition, palmitate oxidation in mitochondria of rats treated with CoA reached values higher than those of control and of rats fed with a high fat diet without CoA.

Animals↗
PubMed1991

Effect of propionyl carnitine on energy charge and adenine nucleotide content of cardiac endothelial cells during hypoxia.

Adenine mucleotide metabolism is very active in endothelial cells. These cells are very rich in xanthine oxidase which may produce oxygen reactive species during ischaemia and reperfusion when a high amount of adenine nucleotides may be catabolized to hypoxanthine. We investigated the effect of propionyl carnitine on energy charge and nucleotide content in cultured endothelial cells during changes in oxygen partial pressure. During hypoxia the adenine nucleotide pool and the energy charge decreased more slowly in the presence of 0.5 mM propionyl carnitine than in the absence of the compound. Furthermore during reoxygenation a more rapid increase of energy charge and adenine nucleotide concentration was observed with propionyl carnitine. These observations suggest that the presence of propionyl carnitine allows the endothelial cells to maintain their functionality and regulatory role on vessel activity for a longer time and decreases the formation of oxygen reactive species due to xanthine oxidase activity on hypoxanthine formed by adenine nucleotide catabolism.

Adenine↗
PubMed1991

Protective effect of propionyl carnitine against peroxidative damage to arterial endothelium membranes.

Endothelial cells may be damaged by oxygen reactive species produced by granulocytes, by transition metal ions or by xanthine oxidase, an enzyme present in great quantity in these cells. Since it has been observed that propionyl carnitine protects the heart from peroxidation, we have investigated the effect of this compound on the formation of thiobarbituric acid reactive oxidation products (TBAR) in endothelial membranes. The peroxidation systems used were a mixture of Fe3+ and Fe2+, hydrogen peroxide and Fe2+, or xanthine oxidase-- xanthine. Propionyl carnitine at millimolar concentrations decreases TBAR formation. The protection is concentration-dependent and is almost absent in the presence of propionate and carnitine. From these results it appears that propionyl carnitine may protect not only myocardium but also vessels from peroxidative damage that occurs during ischaemia and reperfusion.

Animals↗
PubMed1991

Metabolic fate of partially depolymerized chondroitin sulfate administered to the rat.

Partially depolymerized chondroitin sulfate (dCS) was tritiated and given to rats. With both the intramuscular and oral routes of administration the main route of excretion is urine. More than 40% of the radioactivity is present in tissues 24 h after administration. After intramuscular injection, radioactivity plasma levels rapidly increase with a peak at 0.6 h. The separation of the radioactive material on a Biogel P-4 column shows that the radioactivity in the first hour after injection is mainly constituted of dCS with molecular weight higher than 4000 daltons (dCS greater than 4000). The composition of the radioactive material changes with time; after 24 h the dCS greater than 4000 is a few percent of the total radioactivity. A large amount of tritiated water due to exchange and metabolization of dCS is found. Mono-, oligo- and polysaccharides resulting from the breakdown of dCS are also present. After oral administration, plasma radioactivity rapidly increases, with a shoulder and a small peak after 1 h and a large peak after 11 h. A tropism of the radioactivity towards glycosaminoglycan-rich tissues is observed. The presence of dCS greater than 4000 in plasma, synovia and cartilage after oral and intramuscular administrations of dCS may explain the chondroprotective effect of exogenous dCS. In fact, desulfated and sulfated oligo- and polysaccharides have regulatory effects on the synthesis and breakdown of hyaluronate-proteoglycan complexes of cartilage.

Administration, Oral↗
PubMed1990

[Urochemistry].

Explore the source record for details and available documents.

Humans↗
PubMed1990

Production of calcium oxalate monohydrate, dihydrate or trihydrate. A comparative study.

Procedures to obtain calcium oxalate monohydrate, dihydrate and trihydrate are presented and discussed. The influence of several additives and conditions in the formation of calcium oxalate dihydrate crystals are comparatively evaluated. It seems that the presence of colloidal phosphate favours the formation of calcium oxalate dihydrate crystals through heterogeneous nucleation.

Calcium Oxalate↗
PubMed1990

Can a relationship reflect the risk of calcium oxalate urolithiasis?

Different mathematical expressions have been proposed in the literature with the aim to reflect the risk of calcium oxalate urolithiasis. Such expressions, as well as a number of new relationships proposed by us, have been evaluated in 76 patients and 34 normal subjects. Stone-formers were divided into two groups: patients with normal calcium and oxalate excretion and patients with hypercalciuria and/or hyperoxaluria. The results obtained were comparatively evaluated. Several formulae gave some acceptable results, but none of them were excellent. This can be explained by the fact that these discrimination indexes more or less reflect supersaturation and/or inhibition deficit, but none of them reflect promoting factors such as heterogeneous nucleation and/or aggregation capacity.

Calcium Oxalate↗
PubMed1990

On the relation between citrate and calcium in normal and stone-former subjects.

The aim of this work is to evaluate citrate in a group of patients with calcium oxalate urolithiasis and in a control group for detecting possible differences between the two groups. The mean urinary concentration in the stone-formers was found significantly lower than in the controls. Particularly interesting was the correlation study between citrate and calcium. It was found that patients with hypocitraturia have hypercalciuria. Thus, it is particularly interesting to point out the importance of citrate in preventing the risk of lithiasis in the group of stone-formers studied by us.

Adult↗
PubMed1990

Relation between calcium oxalate hydrate form found in renal calculi and some urinary parameters.

In calcium oxalate urolithiasis, the monohydrate and dihydrate forms can be found. The aim of this paper is to examine a group of patients with calcium oxalate calculi to determine the calcium oxalate form and the possible relationship with calcium and other urinary biochemical parameters. It was found that calcium oxalate monohydrate is more frequent in the normocalciuric group and also is associated with a lack of inhibitory capacity, while a mixed calculus of calcium oxalate and phosphate or calcium oxalate dihydrate can be related with hypercalciuria.

Calcium↗
PubMed1990

The role of hyperoxaluria in the formation of calcium oxalate urinary calculi, and its association with other biochemical measurements.

The part played by hyperoxaluria in the formation of calcium oxalate urinary calculi was studied in 153 patients who had each been diagnosed as having calcium oxalate urinary calculi on one or more occasions. Seventy-seven of the patients excreted normal amounts of calcium (less than 6.2 mmol/d), and 76 had hypercalciuria (excretion greater than or equal to 6.2 mmol/d); each group was divided into a further two groups depending on whether the oxalate concentration was above or below 0.16 mmol/l. Pure calcium oxalate stones were more common in patients whose calcium excretion was normal, and mixed calcium oxalate and phosphate stones were more common among hypercalciuric patients. Urinary concentrations/day of magnesium, citrate, and phosphorus were significantly lower in the two groups in which the oxalate concentrations were below 0.16 mmol/l than in a normal control group, and magnesium and phosphorus were significantly lower in the two groups in which oxalate concentrations were less than 0.16 mmol/l than in the two in which they were above that value. The concentration of citrate was also lower, but not significantly so. In addition, the pH of the urine in patients with mixed stones was significantly higher in all groups than when the stones were composed of pure calcium oxalate.

Calcium Oxalate↗
PubMed1990

Metabolic fate of exogenous chondroitin sulfate in the experimental animal.

After the administration of tritiated chondroitin sulfate (CS) by oral and intramuscular route, the distribution of radioactivity was investigated in two opportunist omnivorous animals, namely the rat and the dog. More than 70% of the orally administered radioactivity was absorbed. Independently of the administration route, radioactivity was mainly excreted through the urine. Plasma levels showed a rapid increase after oral administration, followed by a large plateau with a maximum at the 14th and 28th h in the rat and in the dog, respectively. A tropism of the radioactivity was observed towards glycosaminoglycan-rich tissues, such as joint cartilage. The analysis of the molecular weight of the radioactive material showed that compounds with a molecular weight corresponding to those of CS, poly-, oligo- and monosaccharides as well as of tritiated water, were present in the plasma, urine, synovial fluid and cartilage. The level of radioactive low molecular weight material, derived from the metabolism of CS and from the exchange reaction, increased with the time after administration. The high molecular weight fraction represented at least 10% of the orally administered CS.

Administration, Oral↗
PubMed1990

Protection of adenylate pool and energy charge by L-carnitine and coenzyme Q during energy depletion in rat heart slices.

The effect of coenzyme Q, of L-carnitine, and of their combination, on the adenine nucleotide pool and the energy charge has been investigated in rat heart slices subjected to energy depletion and recovery. The addition of coenzyme Q or of L-carnitine alone results in a higher value of the energy charge and of the adenine nucleotide pool after hypoxia, reperfusion and rotenone inhibition of the respiratory chain, as compared to controls without additions. The protective effect is much stronger when the two compounds are given together.

Adenine Nucleotides↗
PubMed1990

Synergic and complementary effects of L-carnitine and coenzyme Q on long-chain fatty acid metabolism and on protection against anthracycline damage.

Exogenous L-carnitine and coenzyme Q are used to protect the heart against anthracycline damage and to enhance energy metabolism in the heart and in the muscle. Though their metabolic function is well known and their effects on anthracycline damage have been largely studied, their combined action has not been investigated. Therefore we have used partially CoQ-depleted bovine mitochondria to evaluate the synergic action of CoQ and carnitine on palmitoylCoA oxidation, as an experimental model in which either CoQ or L-carnitine may be the limiting factor in the oxidation of activated fatty acids. The protective effect exerted by the combined use of L-carnitine and CoQ against damage by the anthracycline derivative doxorubicin has been compared to the protection exerted by each compound alone. The effect was evaluated by assessing oxygen consumption and 14C-leucine incorporation in rat heart slices. The results obtained suggest that the administration of an association of L-carnitine and CoQ exerts a stronger protection against anthracycline damage and induces a greater utilization of fatty acids as compared to the effects of each compound alone.

Animals↗
PubMed1990

[Clinico-pathogenetic observations on the subject of "superficial vasculitis"].

A clinical, histopathologic, laboratory and therapeutic study in 44 subjects with "superficial vasculitis", consecutively observed during the last two years, has been carried out. The findings showed that 1. the anamnesis was sometimes not relevant; 2. the clinical pictures were not in a regular manner correlated with histologic reports (a polymorphonuclear infiltrate with leukocytoclasis or a lymphomononuclear + one); and 3. a non-correlation between clinical, histologic and etiologic data. Infectious agents were responsible, mostly pyogenic bacteria, Mycobacterium tuberculosis, and hepatitis B virus; Chlamydiae were rarely responsible, whereas the etiologic role of Toxoplasma was uncertain. In this respect, drugs were not relevant. All these agents seem to act on the immunological response of the patient with previous microvascular changes (diabetes, chronic venous insufficiency). The latter condition seems to play a predominant role: the recovery of the lesions and/or their relapse shows the same behaviour both in case of etiological and symptomatic therapy.

Adolescent↗