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Biomedical subjects

A Ledda

Publications and source records attributed to A Ledda.

At least 19 recordsLinked to original sources
PubMed1996

Different methods for measuring endogenous digitalis-like factor(s).

It is well recognized that one of the difficulties in the search for endogenous ligand(s) with digitalis-like properties (endogenous digitalis-like factor(s), EDLF) in mammals has been the lack of a unique, specific method for the accurate measurement of EDLF. Using C18 solid-phase extracts of plasma from normal adults and various patient groups, and purified extracts from umbilical cord plasma by affinity resin chromatography and HPLC, different methods to measure EDLF were evaluated. These were: (a) a human placenta radioreceptor assay (RRA) developed on the premise that competition for cardiac glycoside receptors was an absolute requirement for EDLF; (b) the inhibition of 86Rb uptake in human erythrocytes to estimate the potassium transport by the sodium pump; (c) an enzyme immunoassay specific for ouabain recently introduced in the market (DuPont Ouabain EIA Reagent Pack). The human placenta RRA was found to have the same ease of application as immunoassay, but could have major advantages in detecting active molecules, being "biologically more meaningful". Ouabain immunoreactivity correlated with EDLF values obtained by RRA, but in some instances the two assays were completely unrelated. Moreover, the high specificity of the DuPont antibody for ouabain (< 3% cross reactivity with digoxin) could be disadvantageous to detect EDLF not strictly resembling ouabain. The 86Rb uptake inhibition method correlated with RRA for EDLF purified by HPLC. It tested the complete enzymatic cycle and could therefore better reflect the in-vivo inhibitory activity of EDLF. However, it appeared not suitable for the routine EDLF evaluation in clinical studies since it was susceptible to sample osmolarity and required daily isolation of human erythrocytes possibly from the same donor. Results of the present study demonstrate that every assay has its limitations, and would suggest the use of multiple assays for EDLF detection.

Cardenolides↗
PubMed1995

HLA antigen distribution in different clinical subgroups demonstrates genetic heterogeneity in lichen planus.

HLA-A, B, Cw, DR and DQ antigens were serologically determined in 105 patients suffering from lichen planus (LP). Of these patients, 87 had idiopathic LP and 18 had secondary LP. In the first group, 43 had cutaneous LP without mucosal lesions, 17 had cutaneous LP with mucosal lesions and 27 had purely mucosal LP. No HLA antigen was found to be significantly associated with secondary LP or with mucosal idiopathic LP. In cutaneous idiopathic LP with or without mucosal lesions, the HLA-DR1 and DQ1 antigen frequency was significantly increased, and that of HLA-DQ3 significantly decreased. Among the HLA-DR1 cutaneous idiopathic LP patients, 78.5% carried the DRB1*0101 allele, and 21.4% the DRB1*0102 allele, compared with 35.7 and 67.8%, respectively, of the HLA-DR1 controls. Our data demonstrate that idiopathic LP is influenced by HLA-associated genetic susceptibility and resistance factors not involved in secondary LP, and that cutaneous idiopathic LP is a genetically and therefore pathogenetically different condition from purely mucosal idiopathic LP.

Adult↗
PubMed1994

Identification of two different HLA B49 DR4 extended haplotypes in the Sardinian population.

The HLA-B49 DR4 haplotype, which is rare in Caucasoid populations, has a frequency in Sardinia of approximately 6% and a very strong linkage disequilibrium (LD). To better understand its genetic structure, the Bf, C4A and C4B Class III alleles were studied in 56 healthy unrelated Sardinian subjects of B49 DR4 phenotype and in 24 of their families. Moreover, 14 sick subjects with the same phenotype were examined together with five of their families. A group of 285 haplotypes belonging to randomly selected individuals was used as a control population sampling. The distribution of the Bf, C4A and C4B alleles among the healthy probands revealed two main groups of association: one major group of 36 subjects (64.3%) with the BfF, C4A3 and C4B4 alleles and one minor group of 14 subjects (25%) with BfS, C4AQ0 and C4B1. A similar subdivision was also observed in the small group of patients. The family analysis confirmed these results and showed two different B49 DR4 extended haplotypes: one with the F34 complotype in 79.1% of the probands (delta x 1000 = 49.0) and the other with the S01 complotype in 20.8% of the probands (delta x 1000 = 17.3). The first one, in LD with the A1 and Cw7 alleles, has not yet been reported in other populations. The second one seems to be identical to a haplotype already reported in the Spanish population. The molecular analysis of the DRB1 locus carried out in 20 of the 70 probands demonstrated that, in both haplotypes, DR4 was represented by the DRB1*0405 allele.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1994

Successful unrelated bone marrow transplantation in beta-thalassaemia.

A 16-year-old Sardinian girl affected by homozygous beta-thalassaemia was submitted to allogeneic BMT using an HLA-identical, MLC-negative, unrelated donor. The donor and the patient were homozygous for the entire extended haplotype A30, Cw5, B18, F130, DRB1*0301, DRB3*0202, DQA1*0501, DQB1*0201 and heterozygous for DPB1*0301/DPB1*0202. The conditioning regimen consisted of 14 mg/kg busulphan and 160 mg/kg cyclophosphamide. Engraftment was achieved 14 days from BMT and the haematological reconstitution was complete without any signs of acute or chronic GVHD. Seven months after the transplant the patient was in excellent general condition. The hypothesis is advanced that when two HLA extended haplotypes are shared by donors and recipients, particularly in homozygosity, this is a very favourable immunogenetic condition in unrelated BMT.

Adolescent↗
PubMed1993

Association of the HLA-A2, CW2, B27, S31, DR2 haplotype with ankylosing spondylitis. A possible role of non-B27 factors in the disease.

With the aim of searching for HLA haplotypes and non-B27 allele frequency variations in Sardinian AS patients, HLA-A, B, Cw, DR, DQ and Bf, C4A and C4B typing and haplotype assignment was carried out in the families of 25 AS patients and in 44 healthy individuals, all B27 heterozygotes. In the AS patients a significant increase of the A2, Cw2, B27, DR2, DQ1 haplotype was found. This depends only partially on the linkage disequilibrium existing in the Sardinian population between B27 and the other alleles of this haplotype, and rather seems to be due to a primary association of Cw2 and DR2 alleles with AS. Preliminary data seem to show that this haplotype bears the S31 complotype and the DRB1*1601 allele both in the AS patients and in the healthy controls. The pathogenetic implications of these findings are discussed.

Adult↗
PubMed1993

Allogeneic bone marrow transplantation combined with multiple anti-HIV-1 treatment in a case of AIDS.

A 25-year-old woman with AIDS was submitted to HLA-identical allogeneic BMT after cytoablation with busulphan and cyclophosphamide and combined anti-HIV-1 therapy with zidovudine, IFN-alpha 2 and anti-HIV-1-specific T cell clones. Marrow engraftment occurred after 18 days and tests for HIV-1 were negative after 30 days but the hematologic reconstitution of the patient was poor. A second BM infusion from the same donor was ineffective and treatment with GM-CSF only induced a transient increase of the blood cell count, suggesting iatrogenic damage to the BM microenvironment. The development of ARDS led to the death of the patient 10 months after transplantation. Post-mortem investigation did not reveal any active infections and PCR on autopsy tissues was negative for HIV-1.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Study of HLA segregation in 479 thalassemic families.

479 families, each with a proband affected by homozygous beta-thalassemia, were typed for HLA. 224 families with a total of 1020 members were typed for the HLA-A, B, C, DR and DQ loci and 255 families with 1046 family members, were typed for the HLA-A, B, and C loci. Altogether, 896 A, B, C, DR and DQ haplotypes and 1020 A, B and C haplotypes were defined. At the same time, 120 healthy unrelated individuals from the same population were typed and used as controls. The analysis of the results was carried out at antigen, allele, haplotype, genotype and sex ratio level with the aim of looking on the one hand, for the existence of heterogeneity between the probands, the unrelated individuals and the healthy siblings and, on the other, for the existence of any distortion whatsoever of the HLA segregation in either the probands or in the healthy siblings in respect of the expected values according to the Mendelian equilibrium. No significant differences were evident between the probands and the controls by the tests carried out at different levels of the HLA system. This leads us to exclude the existence of an association between beta-thalassemia and HLA in the population studied. Moreover, the analysis of the transmission of the alleles, the haplotypes, the genotypes and the sex-ratio by parents to both affected and to healthy children did not show any clear evidence of segregation distortion in respect of the theoretical values.

Alleles↗
PubMed1992

Role of family history in patients with myocardial infarction. An Italian case-control study. GISSI-EFRIM Investigators.

BACKGROUND: A family history of heart disease has been reported to increase the risk of coronary heart disease. We examined the relation between family history of myocardial infarction (MI) and risk of acute MI to establish the independency of this association, the degree of risk in relation to the number and age of relatives affected, and the possible interaction between family history and other major risk factors for MI. METHODS AND RESULTS: In a case-control study conducted in Italy within the framework of the GISSI-2 Trial, 916 cases of newly diagnosed MI and 1,106 hospital controls were identified. Using a structured questionnaire, data were collected on the history of MI in first-degree relatives and the age at which the event occurred. Compared with subjects without family history of MI in first-degree relatives, the relative risk (RR) of MI was 2.0 (95% confidence interval, CI, 1.6-2.5) in those with one and 3.0 (95% CI, 2.0-4.4) in those with two or more relatives affected (chi 2(1) test for trend, 54.1; p less than 0.001). Such an increase was not substantially affected by allowance for recognized risk factors. The risk related to family history involving at least two relatives was higher for early MI (less than 55 years) (RR, 20.0; 95% CI, 3.3-121.2) compared with later MI (less than or equal to 65 years) (RR, 3.5; 95% CI, 1.8-6.6). When known risk factors were considered for their interaction with family history, the effect on RR was approximately multiplicative for several variables, including smoking, serum cholesterol, hypertension, and hyperlipidemia but not for diabetes and body mass index. Thus, the presence of both family history and smoking and cholesterol levels greater than or equal to 226 mg/dl led to an RR of 14 (95% CI, 3.7-50.0) and 8.3 (95% CI, 1.8-38.7), respectively. CONCLUSIONS: This study indicates that a family history of MI is an independent risk factor for MI, and that the number of relatives and the age at which they were affected is related to the strength of the association. There is a multiplicative effect on RR between family history and several major risk factors for MI.

Case-Control Studies↗
PubMed1989

Absence of liver DNA fragmentation in rats treated with high oral doses of 32 benzodiazepine drugs.

Literature data on mutagenic-carcinogenic activity of benzodiazepines are scarce, restricted to few of them, and contradictory. Consequently, in order to provide additional information for the assessment of the genotoxic risk connected with the use of this family of drugs, 32 benzodiazepines of various chemical structure have been tested for their capability to induce DNA damage in vivo, which is considered a sensitive index of potential mutagenic-carcinogenic activity. The frequency of DNA single-strand breaks and/or alkali-labile sites was checked in the liver of rats given orally a single dose (1 mmol/kg) or 15 successive daily doses (0.2 mmol/kg) by the use of a new viscometric technique capable of detecting one DNA lesion per 10(10) Da. Statistically significant changes of viscometric parameters indicative of liver DNA fragmentation were absent with all 32 benzodiazepines, after both acute and subacute treatments. Since the doses tested in rats were from 100 to more than 5000 times higher than doses usually administered to humans, these negative results are in favor of the absence of mutagenic-carcinogenic effects in patients taking benzodiazepines.

Animals↗
PubMed1987

A computerized system for acquiring DNA solution viscosity data.

A new computerized system for monitoring time-dependent viscosity changes of DNA solutions is reported. It provides an extremely sensitive measure of DNA lesions induced by chemical carcinogens. The described apparatus consists of some precision mechanical modules, derived by an early manual version of the system, and of some new electronic parts as optical sensors, a microprocessor-based unit and a personal computer. The new system allows the analysis of more than one specimen at the same time. Compared with the early manual method of measuring, this computerized system, by removing subjectivity and a certain number of casual and systematic errors that might occur with the operator manual intervention, makes possible the evaluation of the resolving power of the viscometers themselves in detecting viscosity changes.

DNA↗
PubMed1987

Systolic anterior motion of the mitral valve in patients with hypertrophic cardiomyopathy. Disappearance after treatment with amiodarone.

We used amiodarone as the only drug in three consecutive patients with hypertrophic cardiomyopathy, marked systolic anterior motion of the mitral valve on M-mode echocardiogram, and paroxysmal atrial fibrillation. The effective control of atrial fibrillation was associated with good symptomatic relief and with reduction until disappearance of the systolic anterior motion of the mitral valve. These data were confirmed in a follow-up of 46, 30 and 30 months.

Adult↗
PubMed1986

Lack of DNA fragmentation in rats treated with high oral doses of drugs acting on the central nervous system.

Five drugs acting on the central nervous system-chlorpromazine, triflupromazine, thioridazine, chlordiazepoxide, and ethosuximide--which provided conflicting results in previous genotoxicity assays have been tested for their DNA-damaging activity in vivo. The capability of these drugs of inducing DNA fragmentation was investigated by the use of two different techniques: rate of DNA strand separation in alkali as measured by hydroxylapatite chromatography, and changes of DNA viscometric behavior as detected by a new highly sensitive method. DNA damage, as checked by the first technique, was absent in both liver and gastric mucosa of rats given a single p.o. administration of 1/2 LD50 of the drugs. These negative results were confirmed by the subsequent viscometric analysis of liver DNA from rats treated with the same doses.

Animals↗
PubMed1985

Viscometric detection of liver DNA fragmentation in rats treated with ten aromatic amines. Discrepancies with results provided by the alkaline elution technique.

A new viscometric technique, capable of detecting DNA strand breaks and alkali-labile sites by monitoring time-dependent changes of DNA reduced viscosity, has been used to evaluate DNA fragmentation in liver of rats treated with single i.p. doses of ten aromatic amines. Persistent and dose-dependent changes of DNA viscometric parameters, which are considered indicative of DNA fragmentation, were produced by six hepatocarcinogenic aromatic amines: 2-naphthylamine, benzidine, 2,4-diaminotoluene, auramine O, 4-aminoazobenzene, and 4-dimethylaminoazobenzene. In contrast, changes of liver DNA viscometric parameters were minimal and transient or practically absent in rats treated with aniline, 1-naphthylamine, 4,4'-oxydianiline and 2,4-diaminoanisole, all of which are devoid of hepatocarcinogenic activity. The comparison with data previously obtained with the alkaline elution technique demonstrates that the two methods can give different results, and that viscometrically-detected DNA damage is better correlated with carcinogenic activity than DNA damage detected by alkaline elution.

Amines↗
PubMed1984

Phase transitions in nuclei and chromatin. Is nuclear volume controlled by the chromatin or by the nuclear matrix?

Changes in the volume of rat liver nuclei have been monitored as a function of modifications in ionic environment (from 0 to 20 mM), temperature (from 4 to 37 degrees C), and pH (from 1 to 8). An abrupt reduction of nuclear volume occurred with increasing ion concentration, this contraction being more pronounced with bivalent (either Ca2+ or Mg2+) than with monovalent (either Na+ or K+) cations. The lowering of pH produced a similar effect. Parallel changes in chromatin structure took place at the same time as phase-like transitions. Atomic absorption spectroscopy allowed determination of free and nuclei-bound ions, pointing to the presence of a sizeable number of free binding sites for chromatin-DNA even within intact nuclei. DNA-phosphate sites appear to be neutralized by ions strictly according to the size of the electric charge and polyelectrolyte theory. Partial digestion (by micrococcal nuclease) or simple breaks (by chemical carcinogens) of the chromatin-DNA fiber caused respectively elimination or reduction of the abrupt volume changes in the intact nuclei. The apparent role of chromatin structure versus nuclear matrix in determining the shape and volume of intact nuclei is briefly discussed.

Animals↗
PubMed1983

Viscometric analysis of DNA damage in kidney and lung following exposure of rats to small doses of chemical carcinogens.

A new viscometric technique has been used to detect DNA damage in kidney and lung of rats treated with six chemical carcinogens. In alkaline conditions (pH 12.5) the reduced viscosity (eta red) of kidney and lung DNA from control rats increased slowly with time reaching a maximum, (eta red)max, after 9-12 h. Carcinogens, by inducing DNA strand breaks either chemically or indirectly by excision repair or during incubation in alkali, cause a reduction of DNA supercoiling which can be sensitively measured by monitoring changes in viscosity. Computerized analysis of time-viscosity curves showed that a statistically significant reduction of the time required for eta red to reach 95% of its maximum value (t-95) was induced by the following single i.p. doses: N-nitrosodimethylamine (DMN), kidney 0.07 mg/kg, lung 0.28 mg/kg; N-nitrosodiethylamine (DEN), kidney 3.2 mg/kg, lung 12.8 mg/kg; N-nitroso-N-methylurea, kidney and lung 0.5 mg/kg; 1,2-dimethylhydrazine (DMH), kidney 1 mg/kg, lung 16 mg/kg; 4-nitroquinoline-1-oxide (NQO), kidney 2.5 mg/kg, lung 0.63 mg/kg; 2-acetylaminofluorene, kidney and lung 12.5 mg/kg. The decrease of t-95 was constantly dose-related. The comparison with data previously obtained from liver demonstrates that DMN, DEN, DMH and NQO caused the greatest amount of DNA damage in the organ most susceptible to tumor induction. Viscosity changes elicited by DMN, DEN and DMH are quantitatively well correlated with the extent of DNA alkylation.

Animals↗
PubMed1983

Viscometric detection of liver DNA fragmentation in rats treated with minimal doses of chemical carcinogens.

A new technique, using an oscillating viscometer capable of measuring changes of DNA reduced viscosity (eta red), has been used to detect DNA damage in liver of rats treated with various chemical carcinogens. In denaturing conditions (pH 12.5), the eta red of liver DNA from control rats increased slowly with time, reaching a maximum, (eta red)max, after 10 to 13 hr. Single i.p. doses of N-nitrosodimethylamine (0.07 mg/kg), N-nitrosodiethylamine (0.2 mg/kg), N-nitroso-N-methylurea (0.5 mg/kg), 1,2-dimethylhydrazine (0.06 mg/kg), procarbazine (1 mg/kg), methyl methanesulfonate (8 mg/kg), and N-diazoacetylglycine amide (3.7 mg/kg) induced a statistically significant reduction of the time (t95) required for eta red to reach its maximal value. A dose-dependent decrease of t95 was observed for dosages markedly lower than those found to be effective in eliciting DNA fragmentation by the use of alkaline elution or alkaline sucrose gradient sedimentation. 2-Acetylaminofluorene (12.5 mg/kg) and 4-nitroquinoline 1-oxide (10 mg/kg) caused a clear-cut increase of (eta red)max. 7,12-Dimethylbenz(a)anthracene (10 mg/kg) markedly prolonged t95. This viscometric assay of in vivo DNA damage allows a reliable assessment of DNA lesions induced by doses of chemical carcinogens sufficiently small not to produce significant alterations in the pharmacokinetic behavior of these compounds.

Animals↗