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R Conti

Publications and source records attributed to R Conti.

At least 19 recordsLinked to original sources
PubMed1997

Chemical analysis and biological activity of airborne particulate matter.

We examined the chemical composition of the suspended particulate matter in a typical, middle-sized, nonindustrial Italian town in terms of total carcinogenic PAH, heavy metal, and polynuclear azo-aromatic compounds. The chemical data relate to the biological activity of the organic extract of the particulate matter (mutagenicity and mice alveolar macrophage phagocytosis inhibition). The concentration values of benz(a)pyrene, the concentration ratios of selected PAH's, and the GC-MS profile of some typical samples indicate that motor vehicle traffic is the main pollution source. PAH concentration is significantly correlated with mutagenicity and a phagocytosis inhibition of up to 75% was observed at the highest PAH concentration. As far as the effect of meteorological variables on PAH concentration and mutagen-icity is concerned, a statistically significant inverse correlation with temperature was found.

Air Pollutants↗
PubMed1996

Structural, metabolic and ionic requirements for the uptake of L-carnitine by primary rat cortical cells.

L-Carnitine (L-C) is involved in the transport of acyl groups into mitochondria for beta-oxidation, although its role in the adult brain is still uncertain. We have shown before that the uptake of L-carnitine into cultured rat cortical neurones was dependent on temperature as well as the Na gradient and is inhibited by compounds resembling its structure, like gamma-aminobutyric acid (GABA), but most potently by specific GABA uptake blockers. In this study we have characterised this uptake process further. We have shown that the uptake of L-carnitine may be dependent on Cl ions, in addition to Na ions, but non on Ca ions. The L-C uptake was inhibited by substituent anions in the order gluconate (83%) > isethionate (32%), with propionate being ineffective, whereas GABA uptake was inhibited most potently by propionate substitution (79%) and equally by isethionate and gluconate (67%). This L-C uptake process was not affected by the amino acids, glutamine or lysine, up to 1 mM concentration, although beta-alanine at 500 microM caused a 38% inhibition. The uptake of L-C was also significantly inhibited by structurally-related compounds, with a carbon chain length of three to six atoms, possessing an amine group and/or a carboxyl group. At a concentration of 500 microM, 3-aminopropane sulphonic acid (53%), gamma-butyrobetaine (31%), gamma-hydroxybutyric acid (34%) and 4 methylaminobutyric acid (33%). Other compounds were effective only at the lower concentration of 10 microM, such as butyric acid (25%), nicotinic acid (26%), isonicotinic acid (26%), hexanoic acid (23%) and at 100 microM, like 6-aminocapric acid (22%). Drugs suggested to affect membrane properties, such as chlorpromazine, was without effect at 1 or 10 microM, whereas flunarizine (FLU) at 1 microM inhibited both L-C (24%) and GABA uptake (17%). Other drugs like the cholinesterase inhibitors, tacrine and eserine, also had a small inhibitory effect on L-C uptake, reducing it at 1 microM by 22 and 21% respectively, although higher concentrations were toxic (> 100 microM). Pretreatment of the cells with neuraminidase (50 U ml-1, 10 min) reduced the subsequent uptake of both L-C (18%) and GABA (42%). Hypoxia (3 h) also significantly attenuated L-C uptake (42%), however part of these effects were related to the loss of cell viability. In summary, L-C uptake occurs by a complex mechanism which at least in part may occur by a Na/Cl cotransport mechanism, which could be similar, to that of GABA or may even in part occur via the GABA transporter.

Amino Acids↗
PubMed1996

[Motility of the gastric antrum and the gallbladder following oral administration of sulfate-bicarbonate].

The authors evaluate the influence of a sulphate-bicarbonate mineral water on gastric emptying and cholecystic motility. Nine healthy volunteers drunk at settled intervals and with same procedures equal doses of mineral water and tap water on alternate days. Ultrasonographic evaluation of the gastric emptying and cholecystic volumes was performed before and after mineral water and top water drinks at settled intervals. The mean values of the gastric and the cholecystic volumes were calculated and compared at the single times. The results showed a significant colecystocinetic effect of the mineral water compared with tap water. No difference was observed in the gastric emptying with the mineral and tap water. Our work contributes to the knowledge of the pharmacodynamic effects of the mineral water employed and confirms its usefulness in the syndromes based on alterations in bile secretion and bile excretion in duodenum.

Administration, Oral↗
PubMed1995

Biologic effects of prolonged exposure to ELF electromagnetic fields in rats: II. 50 Hz magnetic fields.

To provide possible laboratory support to health risk evaluation associated with long-term, low-intensity magnetic field exposure, 256 male albino rats and an equal number of control animals (initial age 12 weeks) were exposed 22 h/day to a 50 Hz magnetic flux density of 5 microT for 32 weeks (a total of about 5000 h). Hematology was studied from blood samples before exposure to the field and at 12 week intervals. Morphology and histology of liver, heart, mesenteric lymph nodes, and testes as well as brain neurotransmitters were assessed at the end of the exposure period. In two identical sets of experiments, no significant differences in the investigated variables were found between exposed and sham-exposed animals. It is concluded that continuous exposure to a 50 Hz magnetic field of 5 microT from week 12 to week 44, which makes up approximately 70% of the life span of the rat before sacrifice, does not cause changes in growth rate, in the morphology and histology of liver, heart, mesenteric lymph nodes, testes, and bone marrow, in hematology and hematochemistry, or in the neurotransmitters dopamine and serotonin.

Animals↗
PubMed1994

L-carnitine uptake into primary rat cortical cultures: interaction with GABA.

The ability of the primary rat cortical cells to take up L-carnitine increased with the age of the cultures and plateaued at around day 11 up to 25 days in vitro (DIV) when a slight decline was evident and by 32 DIV there was a major decrease in L-carnitine uptake. The uptake of L-carnitine displayed complex components. Elimination of mitochondrial energy supply by NaCN (1 mM), rotenone (1.25 microM) and DNP (50 microM), caused a small but significant decrease in the uptake (21, 11 and 16%, respectively). The uptake was highly dependent on the Na gradient, since ouabain (0.5 mM) and Na free buffer (replaced by 250 mM sucrose), reduced uptake by 54 and 63%, respectively. There was competition of L-carnitine uptake by molecules resembling its structure, e.g. gamma-aminobutyric acid (GABA), acetyl-L-carnitine (ALC), D-carnitine, L-aminocarnitine and L-choline, with GABA being the most potent inhibitor (57% at 50 microM) and L-choline not being significantly active. The Na-dependent uptake of L-carnitine was saturable with a high Km (692 microM) and Vmax (839 pmol/min/mg). This Na-dependent component was not further additive with the GABA (500 microM) or the DNP (50 microM) inhibitable component, suggesting that it represented the same phenomenon, probably the Na gradient dependent transport of L-carnitine. The results indicate that the uptake of L-carnitine occurs by Na-dependent saturable process as well as non-saturable, Na-independent processes. At least the former uptake mechanism is potently inhibited by GABA.

Animals↗
PubMed1993

Studies on the possible biological effects of 50 Hz electric and/or magnetic fields: evaluation of some glycolytic enzymes, glycolytic flux, energy and oxido-reductive potentials in human erythrocytes exposed in vitro to power frequency fields.

An attempt has been made to understand whether 50 Hz electric and magnetic fields (EMFs) are involved in producing bioeffects by exposing human erythrocytes in vitro. The study evaluated some key glycolytic enzymes, glucose consumption, lactate production, energy charge, 2,3-diphosphoglycerate, and reduced glutathione levels, all of which are biochemical parameters significant to erythrocyte function. Cells exposed to individual or superimposed EMFs have not shown any significant difference compared with the controls.

2,3-Diphosphoglycerate↗
PubMed1993

Biologic effects of prolonged exposure to ELF electromagnetic fields in rats. I. 50 Hz electric fields.

A three-year investigation was conducted on the biological effects of high-intensity electric field exposures of rats for up to 18% of their life span. Two hundred and forty adult male rats, divided into groups of 20 animals each, were exposed at ground potential for 8 h/day at 25-kV/m and 100-kV/m 50-Hz electric fields or were sham exposed for 280, 440, and 1240 h. The corresponding ages at sacrifice were 140, 164, and 315 days. An additional group of 40 rats was investigated under similar experimental conditions after 440 h of exposure at floating potential. Independent of exposure duration, mode of grounding, and field strength, no statistical differences in body weight, morphology, and histology of the liver, heart, mesenteric lymph nodes, and blood variables (hematology and serum chemistry) were found in comparison with sham-exposed animals. Plasma levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone (TS) at sacrifice varied widely among experimental animals in the same group but did not differ in exposed compared with sham-exposed rats. A nonsignificant tendency toward a decrease in the testes/body weight ratio was found after 1240 h of exposure. Microscopic examination of a large number of specimens showed no quantitative or qualitative statistical differences in testes alterations either among exposed animals or between exposed and their corresponding sham-exposed groups. We conclude that 50-Hz electric field exposure, even of long duration at very high field strengths, does not induce harmful effects on tissues with high cellular turnover rates and does not impair the reproductive function of rats. Moreover, after exposure, all variables investigated were well within the normal physiological range.

Animals↗
PubMed1993

Changes in motoneuron excitability of masseter muscle following exteroceptive stimuli in Parkinson's disease.

Changes in motoneuron activity of masseter muscle to exteroceptive stimuli were evaluated in parkinsonian patients. Two different electrophysiological procedures were applied, consisting of exteroceptive suppression of the masseter or excitability curves of the masseteric reflex obtained by using exteroceptive conditioning stimuli. Seven patients not yet treated with dopaminergic or anticholinergic drugs were compared with 10 age-matched normal volunteers. Only the second phase of exteroceptive suppression was examined because correct measurement of the first phase was impossible due to the stimulus artefact. No significant differences were observed in exteroceptive suppression between parkinsonian patients and normals. Early and late inhibitory phases of the excitability curve of the masseteric reflex were obtained in both normals and patients. However, parkinsonians showed less inhibitory change than normals in both early and late phase of the curve. This study confirms that reduced inhibition of the masseteric reflex to exteroceptive stimuli is present in Parkinson's disease. The excitability curve of the masseteric reflex represents a more reliable method than exteroceptive suppression in detecting these abnormalities.

Adult↗
PubMed1993

The use of Histoacryl in endodontics.

The oral environment is one of the most complex systems of the human body. It is populated by a variety of microorganisms, with some of the species still not classified. Tissue adhesives, such as cyanoacrylates, have been used in dentistry and in medicine because of their adhesiveness potential to the human tissue, even in the presence of moisture, their biological compatibility, surface isolation, hemostatic properties and bacteriostatic features. Based on these observations, the authors investigated the use of a tissue adhesive (Histoacryl; Laboratório Braun, RJ, Brazil) with the purpose of sealing the remaining dentin, especially in endodontically treated molars and premolars. The results strongly suggest that Histoacryl controls micro-leakage of oral fluids at the filling/tooth interface.

Dental Leakage↗
PubMed1992

[Congenital duodenal stenosis. A case treated in adulthood].

The authors report their experience the diagnosis and management of congenital duodenal malformation in adults. They emphasize problems and difficulties in this disease of pediatric age and the physiopathological adaptation in these years. They point out that surgery can modify important metabolic functions and sub-clinical pathological conditions that the malformation made up.

Adult↗
PubMed1992

Electric and/or magnetic field effects on DNA structure and function in cultured human cells.

Exposure of cultured K562 cells to 50 Hz electric (0.2-20 kV/m), magnetic (0.002-2 G), or combined electric and magnetic fields for up to 24 h did not result in the production of detectable DNA lesions, as assayed by the filter elution technique. The rate of cell growth was also unaffected as well as the intracellular ATP and NAD+ levels. These results indicate that, under the experimental conditions utilized in this study, 50 Hz electric, magnetic and electromagnetic fields are not geno- and cyto-toxic in cultured mammalian cells.

Adenosine Triphosphate↗
PubMed1992

[A rare case of intramedullary epidermoid cyst diagnosed by MRI].

Intramedullary epidermoid cysts are rare entities. A case recently seen on MRI led us to review the literature on the subject. A 9 year old boy developed in a four month-time a spastic paraparesis with a T7-T8 sensitive level. The MRI showed a widening of the spinal cord at the T6 level with an area of decreased signal on T1 weighted images, and a homogeneous round shaped area of increased signal on T2 weighted images. The authors discuss the contribution of MRI to the diagnosis of this lesion. The number of cases of intramedullar epidermoid cysts, like dermoid cysts, diagnosed with this neuroradiological method, is still very limited and the literature only mentions isolated cases.

Child↗
PubMed1992

Surgery for local recurrences following deficient radical mastectomy for breast cancer: a selected series of 39 cases.

Thirty-nine patients with locally recurrent cancer, previously treated elsewhere by mastectomy, were considered. At clinical examination, doubts arose as to the efficiency of previously performed mastectomies. Recurrent lesions, in the absence of distant metastases, were nodular, cutaneous or subcutaneous, in the area of previous 'radical mastectomy'. Second surgery consisted of a wide excision together with a surgical revision of axilla. No radiotherapy was administered to the thoracic wall after surgery. Adjuvant chemotherapy (CMF) was given to 26 node-positive women. Median follow-up was 48 months. Pathological reports showed that portions of mammary gland and axillary lymph nodes had been left behind by primary surgery in 29 and 34 cases, respectively. In 26 cases lymph nodes were metastatically involved. Local control has been maintained in 32 patients, 21 of whom are alive and free of disease.

Adult↗
PubMed1991

Seasonal pattern of glycosylation in frog liver.

The circannual behaviour of glycosylation and protein synthesis in frog liver slices was studied following the incorporation of 3H-galactose and 14C-glucosamine into glycolipids and glycoproteins and 3H-leucine into proteins. The activity of two enzymes the galactosyl-transferase and the N-acetyl-glucosaminyl-1-P-transferase was determined. The incorporations of both sugars into the soluble fraction and into the lipid extract present a maximum during the spring-summer period. The incorporation into the protein fraction displays a different pattern: 14C-Glucosamine and 3H-leucine incorporation increases from winter to a maximum in autumn; the incorporation of 3H-Galactose has a sharp peak during spring. The pattern of glycosyltransferase activities is similar to the pattern of incorporation of the two saccharides into proteins, indicating these enzymes as important control points for glycosylation in Anurae.

Animals↗
PubMed1990

[Simvastatin versus gemfibrozil in the treatment of primary hypercholesterolemia in hypertensive patients treated with hydrochlorothiazide].

Recent pharmacological studies confirmed the role of hypercholesterolemia in the pathogenesis of coronary atherosclerosis. A 10% reduction in cholesterol levels can reduce the risk of coronary heart disease by 15%. However many hypercholesterolemic patients often suffer from arterial hypertension and drugs such as thiazide diuretics cause an imbalance in lipid metabolism. The efficacy and the tolerability of simvastatin (a inhibitor of HGM-CoA reductase) with that of gemfibrozil (a fibric acid derivative, which can reduce the VLDL level) were compared in a placebo-controlled study in 2 groups of patients with primary hypercholesterolemia and mild-to-moderate essential hypertension treated with hydrochlorothiazide. After 10 weeks standard hypolipidemic diet and hydrochlorothiazide (25 mg od) therapy, 30 patients whose cholesterol levels were still greater than or equal to 250 mg/100 ml and whose diastolic blood pressure was less than 95 mmHg were randomized to one of the following treatments: simvastatin, 20 mg od, gemfibrozil, 600 mg bid or placebo, while continuing dietetic and diuretic treatment. After 24 weeks treatment, simvastatin induced a 37% reduction in cholesterol plasma levels, a 9% increase of HDL and a 16% reduction of LDL. APO-A1 showed a 4% increase, while APO-B showed a 3% reduction. Gemfibrozil induced a 20% reduction in plasma triglycerides and a 13% decrease in plasma cholesterol, with a significant 19% increase in HDL and a 11% reduction in LDL. No significant variations in any of the lipid parameters monitored were observed in the placebo group. Treatment with simvastatin or gemfibrozil in hypertensive patients in hydrochlorothiazide monotherapy can reduce total cholesterol and LDL-cholesterol plasma levels, while significantly increasing HDL plasma levels compared to placebo. Simvastatin, however, resulted more efficient than gemfibrozil on total cholesterol or cholesterol fractions.

Adult↗
PubMed1990

[Side effects of spinal nerve root radiography. How to reduce them?].

Contrastographic techniques with intrathecal injections (SRG, Myelo-CT) are widely employed in the diagnostic approach to lumbar pathologic conditions. These techniques allow pathologic changes to be demonstrated and the information they yield helps plan the correct surgical approach. However, these invasive examinations are seldom employed for the high incidence of side-effects. The latter are related to various causes, the identification of which can help reduce the side-effects themselves. The authors analyzed a study population of 522 patients subjected to radiculography, using needles of different gauges (18-23 G), and injected non-ionic contrast medium in doses ranging 5-10 ml. The incidence of side-effects was significantly higher in the patients suffering from usual headache (79/237 = 33%), in those under 40 (87/238 = 37%), and in female patients (86/221 = 39%). The incidence of side-effects was lower with fine needles (41/139 = 17%) and contrast medium in doses less than 8 ml (80/337 = 24%). The patients were divided into 4 subgroups according to the different doses of contrast medium administered and to needle gauges: the above parameters exhibited a percentage decrease (21/161 = 14%) with 21-23 G needles and 8 ml of contrast medium. The authors believe it possible to reduce side-effects by using fine needles and smaller doses of contrast medium.

Adolescent↗
PubMed1989

Thyroid hormone effect on alpha-fetoprotein and albumin coordinate expression by a human hepatoma cell line.

The action of triiodothyronine on the production of alpha-fetoprotein and albumin in serum-free cultures of Hep G2 human hepatoma cells was examined. Our data showed that a marked inhibition (up to 8-fold) of alpha-fetoprotein secretion and an increase in albumin (up to 4-fold) are produced by 10(-8) M triiodothyronine. These effects were slow in their onset and for completion required 20-25 days of treatment with the hormone. However, an exposure of the cells to triiodothyronine for only the first 4 h was sufficient to affect, in a similar way, the secretion of alpha-fetoprotein and albumin when measured 15 days after treatment. The secretion of the two proteins parallels their intracellular levels. The decrease in alpha-fetoprotein production can be explained by a reduction of the RNA coding for the protein. The same is essentially true also for albumin increased secretion and related mRNA expression.

Albumins↗