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Biomedical subjects

R Giordani

Publications and source records attributed to R Giordani.

At least 37 records · Page 2Linked to original sources
PubMed1996

Glomerular and tubular effects of contrast media diatrizoate and iopromide.

The aim of this study is to evaluate the nephrotoxicity of two contrast media (CM), with different physicochemical characteristics: diatrizoate (ionic high-osmolar), iopromide (nonionic low-osmolar). Intravenous urography was performed in 34 patients: 17 were examined with diatrizoate and 17 with iopromide, randomly assigned. Different parameters of glomerular and tubular function were measured before and at 6, 24, and 48 h after urography. Both contrast media induced a reversible increase of urine enzymes, which was significantly higher after diatrizoate. In particular, diatrizoate determined a relevant increase of brush border enzymes gamma-glutamyltransferase (GGT) and alkaline phosphatase (ALP) and of cytosolic enzyme lactate dehydrogenase (LDH), while, after iopromide increases of urinary enzymes were less evident and were significant only for GGT and ALP. In addition, diatrizoate affected other tubular functions (clearances of phosphorus and uric acid) and slightly decreased glomerular function in a few patients. In no case did these glomerular and tubular effects have a clinical relevance. In conclusion, the nonionic low-osmolar contrast medium iopromide appeared less nephrotoxic than diatrizoate. The cost-benefit ratio needs further examination.

Alkaline Phosphatase↗
PubMed1996

Renal effects of prolonged antihypertensive treatment with diltiazem.

The effects of diltiazem (DTZ) treatment on blood pressure, renal function and renal hemodynamics over a six week period of therapy were evaluated in 14 adult patients with mild to moderate hypertension. Their creatinine clearances were 64 to 153 ml/min. After a week of treatment with placebo, DTZ was administered orally at a daily dose of 120 mg b.i.d. Blood pressure decreased from a mean value of 152/99 mm Hg (+/-13/6 SD) up to 144/91 (+/-17/8, P < 0.005) in the supine position and from 149/107 (+/-14/9) to 141/96 (+/-16/9, P < 0.005) in standing position. Heart rate decreased from 74 (+/-9) to 69 (+/-8). Plasma urea, creatinine, uric acid and their clearances as well as GFR and ERPF remained stable throughout the trial. Plasma glucose increased from 81 (+/-15) mg/dl to 98 (+/-30, P < 0.05) and plasma potassium decreased from 4.0 mEq/liter to 3.7 (+/-0.3, P < 0.005). Plasma cholesterol and triglycerides were unmodified. DTZ is an effective antihypertensive agent which does not significantly affect renal function. The effects on plasma glucose and potassium require periodical check-ups of these parameters.

Adult↗
PubMed1996

Zidovudine glucuronidation in human liver: interindividual variability.

Zidovudine 3'-azido-3'-deoxythymidine is the drug chosen for the treatment of patients suffering from AIDS; zidovudine being a potent inhibitor of HIV replication. The drug is extensively metabolized by conjugation with glucuronic acid into an inactive compound, and 30-40% of the dose is eliminated presystemically. We studied the variability and characterized the frequency distribution of the activity of zidovudine glucuronosyl transferase in 93 specimens of human liver. A rapid and reproducible radiometric assay for the glucuronidation of 14C-zidovudine is reported. The method is based on the extraction of the unreacted zidovudine into organic solvents and the radioactivity of the unextractable zidovudine glucuronide was measured in the aqueous phase residue. The rate of zidovudine glucuronidation was neither sex- nor age-dependent, ranged over 1 order of magnitude, and was positively skewed. The possibility that endogenous bilirubin should interact with glucuronidation of zidovudine was explored and the endogenous concentration of bilirubin was measured in the microsomal preparations of 59 liver samples. The final concentration of bilirubin in the assay mixture for zidovudine glucuronidation ranged between 2.2 and 13.2 microM and did not interact with the rate of zidovudine glucuronidation. The kinetics of glucuronosyl transferase towards zidovudine was studied in 20 livers, Michaelis-Menten kinetics were observed and the K(m) estimate ranged over 2-fold with an average of 2.89 mM. These in vitro results are consistent with the view that the rate of glucuronidation varies over 1 order of magnitude in the human liver and its distribution is positively skewed. This variability may modulate the patient's exposition to zidovudine and thereby the efficacy of therapy.

Adult↗
PubMed1996

[Coagulation in hemodialysis].

The authors have evaluated the behaviour of protein C activity, factor X and factor VII coagulant activity, and serum lipoprotein(a) before and after haemodialytic treatment in the plasma of patients on maintenance haemodialysis. The plasma level of protein C activity, depressed before haemodialysis, significantly increased during the course of haemodialysis; factor X and factor VII increased as well despite heparinization; serum lipoprotein(a) was abnormally elevated before haemodialysis and did not change after haemodialysis. In vitro incubation (30' at 37 degrees C) of uremic and healthy blood samples resulted in a decrease of serum lipoprotein(a) concentration. After heparin addition (final concentration 0.5 U/ml) lipoprotein(a) became higher in uremic blood only.

Adult↗
PubMed1995

Kinetic studies of a soluble alpha beta complex of nitrate reductase A from Escherichia coli. Use of various alpha beta mutants with altered beta subunits.

A soluble alpha beta complex of nitrate reductase can be obtained from a strain of Escherichia coli that lacks the narI gene and expresses only the alpha and beta subunits. The beta subunit contains four Fe-S centres and the alpha subunit contains the molybdenum cofactor, which is the site at which nitrate is reduced. Despite the lack of the gamma subunit of the complete enzyme, this complex can still catalyse the reduction of nitrate with artificial electron donors such as benzyl viologen, so that it is suitable for studying the transfer of electrons between these two types of redox centre. To examine whether the electrons from reduced benzyl viologen are initially delivered to the Fe-S centres, or directly to the molybdenum cofactor, or both, we have studied the steady-state kinetics and the binding of benzyl viologen to the alpha beta complex and mutants alpha beta* with altered beta subunits. Reduction of the enzyme by reduced benzyl viologen in the absence of nitrate showed that all four Fe-S centres and the molybdenum cofactor could be reduced. Two classes of site with different equilibrium constants could be distinguished. The kinetic results suggest that benzyl viologen supplies its electrons directly to the molybdenum cofactor, at a rate showing a hyperbolic dependence on the square of the concentration of the electron donor. A reaction mechanism is proposed for the reduction of nitrate catalysed by the alpha beta complex of nitrate reductase with artificial electron donors.

Benzyl Viologen↗
PubMed1995

[An increase in bile acids in the serum of patients with chronic kidney failure].

Measurement of serum bile acids was performed in 86 uremic patients without any liver or bile tract diseases. Thirty-six patients (23 males and 13 females, aged 21-60 years) were on conservative dietary treatment, whereas 50 uremics (31 males and 19 females, aged 23-82 years) were on maintenance hemodialysis. The assays were made by means of enzymatic procedure and confirmed by RIA method too. Elevated serum concentrations of bile acids (> 6 mumol/L) were found in 24 out of the 86 uremics (27.9%), and the prevalence was similar in patients on conservative (10/36, 27.7%) and on dialysis treatment (14/50, 28%). Then, abnormally elevated concentrations of circulating bile acids are present in a quite high percentage of uremics both on hemodialysis and on conservative dietary therapy. The existence of a subclinical liver disease or an abnormal entero-hepatic cycle of bile acids might explain these findings.

Adult↗
PubMed1992

Determination of blood constituents reference values in broilers.

Eight hundred broilers were examined to define the reference values of nine blood constituents (total proteins, albumin, total and free cholesterol, triglycerides, aspartate aminotransferase (AST), alkaline phosphatase (ALP), calcium, and phosphorus). The broilers, coming from 20 different commercial poultry operations, were equally divided into different groups according to age (21 and 45 days), strain (Arbor Acres and Hybro), sex, and sampling season (summer or winter). Age and sampling season were the variation sources that most influenced the values of the hematochemical variables examined. The interaction of age with strain influenced total proteins total and free cholesterol, triglycerides, and ALP. The interaction of age with sampling season influenced all hematochemical constituents except triglycerides. Reference limits defined by .975 and .025 fractiles were computed for each blood constituent according to the significance of different variation sources and their combinations. Reference limits defined herein could be used as indicators of metabolic and health conditions of a poultry farm.

Age Factors↗
PubMed1992

[Heterosexual transmission of HIV and a control organization model consisting of female subjects at the USL no. 36 Drug Control Service of Lugo].

Human immunodeficiency virus-HIV heterosexual transmission is going to become the main problem in controlling the spread of HIV; our experience confirms the increased risk when genital lesions are present. These data advise to attend gynaecologic control of female drug addicts, often affected by sexually transmitted diseases, in order to realize primary and secondary HIV spreading prevention.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[Purification of lipase from latex of Euphorbia characias by an extraction method with apolar solvent].

A lipase from the latex of Euphorbia characias was purified using a new method involving extraction by apolar solvent and adsorption chromatography on silica. The lipase (specific activity 1,500 IU/mg of protein) was eluted from silica complexed with a lipid. The main proteic fraction, showing a molecular weight of 38,000, was inactive when dissociated from the lipid fraction. It was necessary to reassociate the lipid and proteic fractions for 72% of the lipolytic activity to be recovered.

Chromatography, Thin Layer↗
PubMed1991

Therapeutic efficacy and renal effects of cefonicid in the treatment of difficult urinary tract infections.

UNLABELLED: EFFICACY, renal effects and nephrotoxicity of the cephalosporin cefonicid (CEF) were evaluated in 11 adult patients with urinary tract infection and varying renal function (creatinine cl 19-161 ml/min, mean 75). CEF was administered i.m. for 7 days at a daily dose adjusted to renal function of the patients. EFFICACY: At the 4th day and at the end of the treatment urine cultures were negative in all cases; a recurrence of the infection was observed in 4 patients 10 days after completion of therapy. Renal effects and nephrotoxicity: CEF neither modified plasma creatinine, urea, uric acid and their renal clearances nor glomerular filtration rate. Only the urinary enzyme activity of alanine aminopeptidase increased slightly at the end of the therapy. It returned to basal values in the post-treatment period. Urinary enzyme activities of gamma-glutamyltransferase, alkaline phosphatase, N-acetyl-beta-D-glucosaminidase and lysozyme were unmodified during and after treatment with CEF. These results indicate that CEF is an effective antimicrobial agent which does not influence renal function, nor cause nephrotoxic effects.

Adult↗
PubMed1990

Effects on renal hemodynamics and tubular function of the contrast medium iohexol in renal patients.

Renal function was assessed in 20 (11 female and 9 male, age 21-76 years, mean 53) renal patients with a creatinine clearance 25-145 ml/min, mean 95, to evaluate the effects of iohexol, a non-ionic low-osmolar contrast medium. Intravenous urography was performed in 16 patients and computed body tomography in 4, using a dose of iohexol ranged between 0.6-3.3 (mean 1.17) g/kg b.w. Different parameters of renal function were determined in the week preceding and 1, 3 and 5 days after the administration of iohexol. The principal renal effect of iohexol was an increase of urinary alanine aminopeptidase, gamma-glutamyltransferase, lactate dehydrogenase, alkaline phosphatase and N-acetyl-beta-D-glucosaminidase. The maximum increase of enzymuria was observed on day 1 after the administration of iohexol. In most cases enzymes returned to base-line values within 3 days. No relevant variation of renal hemodynamics (glomerular filtration rate and effective renal plasma flow) was observed after iohexol. In conclusion, iohexol can increase of urinary enzymes, but the effect is rapidly reversible and is not accompanied by a clinically significant impairment of renal hemodynamics.

Acetylglucosaminidase↗
PubMed1989

Molecular organization and clustering of cell-wall-bound enzymes as a source of kinetic apparent co-operativity.

When fixed charges and enzyme molecules are not homogeneously distributed in a matrix, the degree of organization of charges, of enzyme molecules and of charges with respect to enzyme molecules modulate the enzyme reaction rate. The overall reaction velocity of the bound enzyme system may be expressed in terms of monovariate moments of the charge density distribution and of the bivariate moments of the charge and enzyme density distributions. With respect to the situation where fixed charges and enzyme molecules are randomly distributed in the matrix, the molecular organization, as expressed by the monovariate and bivariate moments results in an increase or a decrease, of the overall reaction rate, as well as in the appearance of a kinetic cooperativity. The degree of spatial organization of objects may be expressed quantitatively through the concept of minimal spanning tree. This concept may thus be applied to the quantification of the degree of order that may exist in the bidimensional distribution of enzyme molecules in a charged matrix. Primary walls of isolated plant cells in sterile culture behave as a polyanion and contain different enzymes. The spatial distribution in sycamore cell walls of an acid phosphatase has been studied through the concept of minimal spanning tree and shown to be non-randomly distributed in the polyanionic matrix, but clustered in that matrix. This spatial organization results in a modulation of the reaction rate of the cell-wall-bound phosphatase reaction. Both the theoretical and experimental results presented in this study leave little doubt as to the validity of the idea that in situ the organization of fixed charges and enzyme molecules modulate the overall dynamics of enzyme reactions.

Acid Phosphatase↗
PubMed1989

A rational postoperative follow-up with carcinoembryonic antigen, tissue polypeptide antigen, and urinary hydroxyproline in breast cancer patients.

Breast cancer patients (n = 224) aged 28 to 81 were postoperatively followed up with serial determinations of carcinoembryonic antigen (CEA), tissue polypeptide antigen (TPA), and urinary hydroxyproline (OHP). The clinical usefulness of these tumor markers to diagnose and monitor distant metastases was compared with that of the imaging techniques commonly used to monitor breast cancer patients (bone scanning [BS], liver echography [LE], chest radiograph, and skeletal radiograph). So far, 23 patients withdrew from the study, and distant metastases occurred in 33 patients. In 91% of the metastatic patients, constant elevation or progressive increase in serum CEA and/or TPA levels were the first pathologic findings of the relapse. Of the remaining 168 nonrelapsed patients, 122 were followed up longer than 24 months (43 +/- 17 months; mean +/- SD). In these 122 patients the false-positive results of CEA, TPA, and OHP were 0.8%, 2.4%, and 0%, respectively, when used simultaneously with clinical examination and the common laboratory examinations. BS and LE are the only imaging techniques that showed such a high sensitivity to be suitable in the postoperative follow-up of breast cancer patients. Nevertheless, because BS has a low specificity and is not harmless, it should be performed at longer intervals than tumor markers. Eventually, in the relapsed patients, TPA and OHP well reflected the response to treatment better than CEA and prevented useless radiologic examinations.

Adult↗
PubMed1988

Isolation, molecular properties and kinetic studies of a strict beta-fucosidase from Lactuca sativa latex. Its possible role in the cell-wall degradation of articulated laticifers.

A beta-fucosidase located in the latex serum of Lactuca sativa has been isolated and purified to homogeneity. This enzyme greatly differs from the other fucosidases already known in that it is strictly specific for the fucosyl residue and for the anomeric beta carbon. It is the first time that such an enzyme is shown to exist. The enzyme is a monomer and its molecular mass is close to 37 kDa. Its sedimentation constant is equal to 2.8 S. It is very stable at pH 5.5 in citrate/phosphate buffer but extensive denaturation occurs up to pH 7.5. Kinetic studies have shown that two ionization steps probably control the rate of the enzymatic hydrolysis. No precise information could be obtained about the possible in vivo role of this beta-fucosidase. However, the pure enzyme can release fucose from the cell walls obtained from hypocotyls of L. sativa. This result may be taken as evidence for the presence of beta-fucosidic links in these walls so that the enzyme could be involved in the differentiation of articulated laticifers.

Amino Acids↗