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Biomedical subjects

G Ricci

Publications and source records attributed to G Ricci.

At least 199 records · Page 11Linked to original sources
PubMed1993

The importance of the highest normokalemia in the treatment of early hepatic encephalopathy.

An inverse relation is known to link blood potassium with renal synthesis and the release of ammonia. Given the liability of hyperammonemia for precipitating hepatic encephalopathy (HE), 28 patients affected by stage I HE were equally divided into two groups and maintained up to their death at the highest (5.4-5.5 mEq/l) or the lowest (3.5-3.6 mEq/l) normokalemia levels. When compared with the lowest normokalemia group, the highest one showed an early, albeit transient, improvement in the mental state (as assessed by both EEG and psychiatric investigations) and to a lesser extent in hepatic functions (as assessed by the variations in serum bilirubin, GPT, GGT and plasma prothrombin time). In the highest normokalemia group the survival was also prolonged. The cause of this improvement may be related to the induced decrease in blood pH, the consequent depression of renal ammoniagenesis and the rise in the arterial and urine NH+4/NH3 ratios. These factors reduce the entry of ammonia into the cells and enhance the urinary excretion of this metabolite, respectively.

Adult↗
PubMed1993

[Evoked acoustic oto-emissions in patients with diabetes mellitus].

The purpose of this study was to evaluate the cochlear function in patients with diabetes mellitus by analysis of evoked otoacoustic emissions (EOAE). EOAE were studied in 20 diabetic patients with normal hearing. The parameters used for analysis were the EOAE intensity and amplitude measured per 100 Hz frequency bands between 700 and 4000 Hz These data were compared to the data obtained in a group of non-diabetic control subjects with normal hearing using a Student's t test. The mean EOAE intensity and amplitude by 100 Hz frequency band was significantly lower in diabetic patients than in the control group. This seems to indicate the existence of an alteration in cochlear micromechanics in diabetic patients possibly due to changes in the functioning of the hair cells.

Adult↗
PubMed1993

[The behavior of the fibrinogen polymerization curve in hypercholesterolemic subjects].

Several epidemiological and clinical studies performed in subjects with risk factors for atherosclerotic cardiovascular events, have shown changes in plasma levels and/or activities of coagulation factors that could suggest a prothrombotic state. We studied the behaviour of the fibrinogen polymerization curve (FPC), a spectrophotometric technique evaluating the kinetics of fibrinogen transformation into fibrin, in 68 subjects with and without hypercholesterolemia. Significant differences were found between FPCs of subjects with serum cholesterol > 240 mg/dl and < or = 240 mg/dl respectively. In fact, FPCs of the first group showed high reaction velocity rate, short latency time and higher optical density rate, final readings; besides, the behaviour of FPCs was not correlated to plasma fibrinogen concentrations. Therefore, FPC could be a useful test to identify a thrombophilic condition in hypercholesterolemic patients.

Adult↗
PubMed1992

Age-related anticonvulsant activity of NMDA in the rat caudate-putamen.

Striatal pathways are important for modulating the threshold for seizures in the rat forebrain. N-Methyl-D-aspartate (NMDA), an excitatory amino acid derivative and powerful anticonvulsant agent, when injected into the brain, has been shown to protect adult rats against kindling and pilocarpine-induced seizures when injected into the caudate-putamen. The present study examines whether the anticonvulsant action of NMDA in the caudate-putamen varies with age. Bilateral striatal administration of NMDA was effective in suppressing bicuculline-induced seizures in rats older than 23 days of age. The results suggest that striatal pathways involved in the anticonvulsant activity of NMDA in the caudate-putamen are not functionally active in developing rats before the 4th week of life.

Aging↗
PubMed1992

Chemical modification of human placental glutathione transferase by pyridoxal 5'-phosphate.

Incubation of GST pi from human placenta with 8 mM PLP resulted in a rapid loss of activity during the first 10 min, concomitant with a Schiff base formation. This inactivation was probably due to the formation of a reversible adduct between PLP and the enzyme. After sodium borohydride treatment this adduct was reduced and stabilized. Stoichiometry and peptide isolation studies showed that three lysine residues were modified during reaction of GST and PLP. Protection of the enzyme against inactivation was achieved in the presence of 4 mM GSH suggesting that at least one lysyl residue is associated with the substrate binding site. Peptide mapping by digesting the enzyme with trypsin revealed that lysine shielded by GSH is Lys-127. Our results suggest that this residue may play an important role in enzymatic activity.

Amino Acid Sequence↗
PubMed1992

[Evoked otoacoustic emissions in diagnosis of cochlear hearing disorders].

The authors consider the possibility of routine use of evoked otoacoustic emissions (EOE) in diagnosis of sensory hearing loss by comparison of EOE curves with relative curves obtained by pure tone audiometry. 180 ears with sensory hearing loss of different aetiologies were examined. EOE were obtained by application of Bray and Kemp's Evoked Otoacustic Measurement Package (ILO88). The results obtained show a close correlation between presence of EOE and real hearing losses of different frequencies obtained by pure tone audiometric evaluation. We could detect no EOE with hearing losses over 50 dB HL at 500 Hz, 40 dB HL at 1000 Hz, 50 dB HL at 2000 Hz and 85 dB HL at 4000 Hz. With a rate of middle hearing loss over 45 dB HL we also did not find EOE for the whole frequency range. On the base of this study, the authors conclude that EOE explore the functional integrity of those parts of the cochlea that correspond to the middle frequencies of hearing range. If EOE are not detectable, statements on the nature and extent of hearing loss on the base of this examination are not valid.

Adolescent↗
PubMed1992

Anti-HCV antibodies and hepatocellular carcinoma. Relationship in a medium-risk population.

By means of an accurate immunoenzymatic assay, the prevalence was studied of antibodies to hepatitis C virus (HCV) in three different populations: 74 patients affected with hepatocellular carcinoma (HCC) on preexisting cirrhosis, 82 patients with liver cirrhosis but with no apparent neoplasm, and 70 control subjects, hospitalized for various conditions, of internal medicine or geriatric interest. 70.2% of HCC patients exhibited anti-HBC antibodies, versus 47.5% of cirrhotic subjects with no tumor and 7.1% of controls. Such results suggest the possible role of HCV in the etiopathogenesis of HCC, and its possible synergy with other agents-e.g., hepatitis B virus, alcohol--in causing chronically injured hepatocytes to become neoplastic.

Aged↗
PubMed1992

[Results of audiometric and vestibular tests in Cogan syndrome: apropos of a case].

The authors report on a case of Cogan's syndrome pointing out that hearing loss is due both to cochlear lesions from likely immunitary origin as well as to widespread alterations of auditory central nervous structures. This interpretation allows to explain the apparent discrepancy of the found clinical and instrumental data. From a therapeutic point of view, the authors assert the necessity of an early corticosteroid therapy to obtain some appreciable result. Anyway, they point out how prognosis for auditory function in Cogan's syndrome is often very poor.

Adult↗
PubMed1992

[Clinical methodology employed to solve a case of probable sarcoidosis].

A case of interstitial lung disease with fever and arthralgia is described. Sarcoidosis was very probable, but the patient refused the invasive investigations that were needed in order to obtain a histological diagnosis of certainty. We discuss the clinical methodology employed to solve the case.

Adult↗
PubMed1992

[Evoked oto-acoustic potentials in the first 60 hours of life].

In order to verify how age influences in the first days of life the presence of Evoked Otoacoustic Emissions (EOAE), the authors tested 52 newborns. They conclude that EOAE is a reliable technique as an early detection test of hearing loss in children. However, a high percentage of false positive cases during the very first days of life advises against its too early utilization.

Evoked Potentials, Auditory, Brain Stem↗
PubMed1992

[Bacteriology of chronic maxillary sinusitis].

132 patients with chronic maxillary sinusitis were included in this bacteriological study of the intrasinus exudate obtained by a radical antrostomy or antral puncture. We found 78.3% aerobes, 21.7% anaerobes, 51.5% gram positive and 48.5% gram negative micro-organisms, but no fungi in 120 cultures. The commonest aerobic species was Haemophylus (20%), whereas Peptococcus and Bacteroides were the commonest anaerobes (10%).

Adolescent↗
PubMed1991

Sulfur-containing cyclic ketimines and imino acids. A novel family of endogenous products in the search for a role.

Aminoethylcysteine, lanthionine, cystathionine and cystine are mono-deaminated either by L-amino-acid oxidase or by a transaminase exhibiting the properties described for glutamine transaminase. The deaminated products cyclize producing the respective ketimines. Authentic samples of each ketimine were prepared by reacting the appropriate aminothiol compound with bromopyruvate, except cystine ketimine which required the interaction of thiopyruvate with cystine sulfoxide. Reduction of the first three mentioned ketimines with NaBH4 yields the respective derivatives with the saturated rings of thiomorpholine and hexahydrothiazepine. The same reduction is carried out enzymically by a reductase extracted from mammalian tissues. Properties of the members of this family of compounds are described. Gas chromatography followed by mass spectrometry permits the identification of most of these products. HPLC is very useful for the determination of the ketimines by taking advantage of specific absorbance at 380 nm obtained by prior derivatization with phenylisothiocyanate. Adaptation of these and other analytical procedures to biological samples disclosed the presence of most of these compounds in bovine brain and in human urine. By using [35S]lanthionine ketimine as a representative member of the ketimine group, the specific, high-affinity, saturable and reversible binding to bovine brain membranes has been demonstrated. The binding is removed by aminoethylcysteine ketimine and by cystathionine ketimine indicating the occurrence in bovine brain of a common binding site for ketimines. The reduced ketimines are totally ineffective in competing with [35S]lanthionine ketimine. Alltogether these findings are highly indicative for the existence in mammals of a novel class of endogenous sulfur-containing cyclic products provided with a possible neurochemical function to be investigated further.

Amino Acids, Sulfur↗
PubMed1991

Redox forms of human placenta glutathione transferase.

Human placenta glutathione transferase (EC 2.5.1.18) pi undergoes an oxidative inactivation which leads to the formation of an inactive enzymatic form which is homogeneous in several chromatographic and electrophoretic conditions. This process is pH dependent, and it occurs at appreciable rate in alkaline conditions and in the presence of metal ions. Dithiothreitol treatment completely restores the active form. -SH titration data and electrophoretic studies performed both on the oxidized and reduced forms indicate that one intrachain disulfide is formed, probably between the two faster reacting cysteinyl groups of each subunit. By the use of a specific fluorescent thiol reagent the disulfide forming cysteines have been identified as the 47th and 101th residues. The disulfide formation causes changes in the tertiary structure of this transferase as appears by CD, UV, and fluorometric analyses; evidences are provided that one or both tryptophanyl residues of each subunit together with a number of tyrosyl residues are exposed to a more hydrophilic environment in the oxidized form. Moreover, electrophoretic data indicate that the subunit of the oxidized enzyme has an apparent molecular mass lower than that of the reduced transferase, thereby confirming structural differences between these forms.

Circular Dichroism↗
PubMed1991

Interaction of glutathione transferase from horse erythrocytes with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole.

7-Chloro-4-nitrobenzo-2-oxa-1,3-diazole reacts with two thiol groups of the dimeric horse erythrocyte glutathione transferase at pH 5.0, with strong inactivation reversible on dithiothreitol treatment. The inactivation kinetic follows a biphasic pattern, similar to that caused by other thiol reagents as recently reported. Both S-methylglutathione and 1-chloro-2,4-dinitrobenzene protect the enzyme from inactivation. Analysis of the reactive SH group-containing peptide gives the sequence Ala-Ser-Cys-Leu-Tyr, identical with that of the peptide that contains the reactive cysteine 47 of the human placental transferase. In the presence of glutathione, the enzyme is not inactivated by this reagent, but it catalyzes its conjugation to glutathione. At higher pH values, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole reacts with 2 tyrosines/dimer and lysines, as well as with cysteines. Reaction with lysine seems essentially without effect on activity; whether the reactive tyrosines are important for activity could not be determined using this reagent only. However, 2 tyrosines among the 4 that are nitrated by tetranitro-methane are important for activity.

4-Chloro-7-nitrobenzofurazan↗
PubMed1991

Short term changes in cardiovascular risk factors in the Di.S.Co. Intervention Project. Research Group of the DI.S.Co. Project.

The Di.S.Co. Project--Sezze District Community Control--is aimed at achieving in the general population the prevention of chronic diseases through community intervention. Two areas are enrolled, one for intervention (25,706 subjects) and one for reference (12,655 subjects). In 1983 the first survey was conducted on a sample of males and females aged 20-69, and some risk factors for cardiovascular diseases were measured. In 1986 a second screening was conducted on the same sample examined in 1983 and in a new one to evaluate the effect of community treatment during the three-year intervention. The main net differences obtained in the treatment area against controls (by the paired analysis), adjusted by the initial levels of the risk factors considered, were: in males body mass index: -1.3% and number of cigarettes smoked per day: -5.1%; in females systolic blood pressure: -2.1%, body mass index: -3.2% and number of cigarettes smoked per day: -34.4%. The theoretical probability of death from atherosclerotic cardiovascular diseases in 25 years was estimated by the multiple logistic function and in three years it increased by 1% in males, while for females it decreased by 6.5%.

Adult↗
PubMed1991

Aortic glutathione-related antioxidant defences in rabbits subjected to suprarenal aortic coarctation hypertension.

In seven rabbits subjected to suprarenal aortic coarctation hypertension, the segments above and below the coarctation were tested for the antioxidant defences (i.e. acid-soluble thiol compounds, selenium-dependent and selenium-independent glutathione peroxidase, glutathione reductase, glutathione transferase) and thiobarbituric acid-reactive substances. Seven sham-operated rabbits served as controls. Systolic blood pressure proximal to the ligature increased significantly with respect to pre-operative values after 16 days (117 +/- 8.3 vs 71.7 +/- 5.2 mmHg, P less than 0.05), while pressure distal to the ligature remained normotensive. Higher values of acid-soluble thiol compounds, thiobarbituric acid-reactive substances and increased activities of selenium-dependent glutathione peroxidase, glutathione reductase and glutathione transferase were assayed in the suprarenal with respect to the subrenal segment in both groups. However, the values of the upper segments were more elevated in the experimental group than in controls, but no differences were observed in the lower segments. Glutathione peroxidase activity assayed with cumene hydroperoxide was higher than the activity assayed with hydrogen peroxide in the hypertensive segments, but no differences were detected in the substenotic and control segments. Furthermore, an isoenzymatic form of glutathione transferase, analogous to rat 8-8 glutathione transferase isoenzyme, was detected by immunodiffusion in the hypertensive aorta. The following conclusions may be drawn: (1) a biochemical gradient in glutathione-related enzymes, acid-soluble thiol compounds and thiobarbituric acid-reactive substances between the proximal and distal aorta seems to exist in control rabbits; (2) suprarenal aortic coarctation induces a significant increase in glutathione-related antioxidant defences and thiobarbituric acid-reactive substances of the hypertensive aortic wall.

Animals↗
PubMed1991

Regional distribution of glutathione-related antioxidant defences in the normal rabbit aorta.

In 6 normal rabbits, the aortic arch, the descending thoracic and the abdominal aorta were tested for non proteic thiol compounds, selenium-dependent and selenium-independent glutatione peroxidase, glutatione reductase, glutatione transferase and thiobarbituric acid reactive substances. The aortic arch showed the greatest content of non proteic thiol compounds and thiobarbituric acid reactive substances, associated to the highest activities of glutathione-related enzymes. However, not significant differences were detectable between aortic arch and descending thoracic aorta, except for the glutathione transferase activity (0.395 +/- 0.031 vs 0.330 +/- 0.053 U/mg protein, p less than 0.05). Furthermore, both aortic arch and descending thoracic aorta showed significantly higher values of non proteic thiol compounds (46.05 +/- 10.15% and 33 +/- 13.5%, p less than 0.05), selenium-dependent glutathione peroxidase activity (70.35 +/- 26% and 54.3 +/- 9.5%, p less than 0.05), glutathione reductase activity (25.4 +/- 7% and 18.4 +/- 4.5%, p less than 0.05) and thiobarbituric acid reactive substances (65.8 +/- 18% and 47.2 +/- 17%, p less than 0.05) with respect to the abdominal aorta. The selenium-independent glutathione peroxidase activity was not detectable. In conclusion, a biochemical gradient in glutathione-related antioxidant defences and thiobarbituric acid reactive substances proceeding from the proximal to the distal segments seems to exist in the normal rabbit aorta. These results could contribute to explain the non homogeneous distribution of experimental atherosclerosis in the rabbit aorta.

Animals↗