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M Sampietro

Publications and source records attributed to M Sampietro.

At least 55 records · Page 3Linked to original sources
PubMed1996

Iron stores, response to alpha-interferon therapy, and effects of iron depletion in chronic hepatitis C.

We studied 81 patients with chronic hepatitis C to investigate the relationship between iron and alpha-interferon response. Sixty-one patients (group A) were given alpha-interferon irrespective of iron status, whereas 20 (group B) with iron overload, were iron depleted before alpha-interferon therapy. In group A, 21 patients responded to alpha-interferon and 40 were non-responders. Increased iron indices were significantly more frequent in non-responders than responders. Multivariate analysis showed that among the independent variables evaluated, only gamma-GT and liver iron concentration predicted therapy outcome. After phlebotomy treatment, serum alanine aminotransferase fell significantly both in patients of group B (196 +/- 122 IU/l vs 82 +/- 37 IU/l, p < 10(-6)) and in 12 non-responders of group A (198 +/- 89 IU/l vs 107 +/- 81 IU/l, p < 10(-6)). In 16 iron depleted patients, eight from each group, subsequent treatment with alpha-interferon produced a response in only one patient. These results suggest that increased liver iron is a negative prognostic factor for alpha-interferon response in chronic hepatitis C. Iron depletion had a beneficial effect on serum alanine aminotransferase in all the patients treated, but did not improve the response to alpha-interferon.

Adult↗
PubMed1995

Single-tube reverse transcription and heminested polymerase chain reaction of hepatitis C virus RNA to detect viremia in serologically negative hemodialysis patients.

Detection of hepatitis C virus genome is the only method currently available for detecting viremia in infected individuals. We describe a substantial simplification of current methods for viral RNA reverse transcription and polymerase chain reaction amplification, which allows cDNA synthesis and nested amplification in a single tube; this is achieved through compartmentalization of the reagents for the two reactions with a wax barrier. This procedure retains a high sensitivity: analysis of serum samples from hemodialysis patients, a high-risk group for hepatitis C virus infection, confirmed the presence of the virus in 88% of antibody-positive patients and detected viremia in patients without serological or biochemical evidence of hepatitis C virus infection.

Adult↗
PubMed1995

High prevalence of a rare hepatitis C virus in patients treated in the same hemodialysis unit: evidence for nosocomial transmission of HCV.

Hepatitis C virus (HCV) is a major cause of hepatitis among patients treated with maintenance hemodialysis. Blood transfusion appears to be the primary risk factor, but nosocomial transmission of HCV in the dialytic environment has been hypothesized. We addressed this issue by analyzing the individual variation of genomic sequences of HCV in 28 patients on chronic hemodialysis (HD) from the same department and 25 environmentally unrelated patients with HCV-related liver disease. Genome variations of HCV were studied by single strand conformation polymorphism (SSCP) analysis of polymerase chain reaction products obtained from the 5'-untranslated region of the viral genome and by sequence analysis. Six different SSCP patterns were identified in HD patients versus 16 in control patients. Among HD patients the three more frequent SSCP patterns accounted for 85% of observations, while in the control group each pattern was found in 4 to 12% of patients. The ability of SSCP to discriminate sequence variation was proven by sequence analysis which confirmed identity/diversity of sequences selected by SSCP. Moreover, sequence analysis permitted a recognition of the most frequent genome observed in HD patients as a type 4 HCV, which is considered to be rare in the Italian population. The relative homogeneity of HCV variants in HD patients treated in the same HD and the high prevalence in this unit of a rare viral variant support the possibility of a nosocomial transmission of HCV in the dialytic environment.

Adult↗
PubMed1995

Liver iron concentration in chronic viral hepatitis: a study of 98 patients.

OBJECTIVE: To compare the liver iron concentration (LIC) of Italian patients with chronic hepatitis B and C with those of controls, to evaluate increased LIC frequency in patients and to investigate the influence of the haemochromatosis gene in the development of liver iron overload. DESIGN AND SETTING: Prospective controlled trial in two northern Italian hospitals. PATIENTS: Ninety-eight patients (61 men and 37 women), 85 with chronic hepatitis C and 13 with chronic hepatitis B, and 38 control individuals (20 men and 18 women). METHODS: Atomic absorption spectrophotometry was used to determine LIC; standard lymphocytotoxicity test was used for HLA typing in patients with increased LIC; and family studies were performed for patients with major iron overload. RESULTS: Mean LIC was significantly higher in both patient groups than in the controls. Thirty-five patients (36%) had an increased LIC. Twenty-six of these patients had a minor iron overload, whereas nine (9.2%) had a major overload. HLA-A3 antigen was present in five out of the 26 and in four out of the nine patients, respectively. Family studies revealed two siblings HLA-identical to their own proband without evidence of iron overload and chronic hepatitis. CONCLUSION: Increased LIC is frequent in Italian patients with chronic hepatitis. The mechanism by which the hepatitis virus promotes liver iron accumulation is not known, but it can favour the development of major iron overload in some cases. HLA-A3 antigen prevalence and family studies suggest that in these cases a single haemochromatosis gene probably coexists with the viral infection. LIC should be determined as part of the screening evaluation in patients with suspected chronic hepatitis B or C.

Aged↗
PubMed1994

G6PD Ferrara I has the same two mutations as G6PD A(-) but a distinct biochemical phenotype.

The cloning and sequencing of the normal glucose-6-phosphate dehydrogenase (G6PD) gene has led to the study of the molecular defects that determine enzymatic variants. In this paper, we describe the mutations responsible for the Ferrara I variant in an Italian man with a family history of favism, from the Po delta. Nucleotide sequencing of this variant showed a G-->A mutation at nucleotide 202 in exon IV causing a Val-->Met amino acid exchange, and a second A-->G mutation at nucleotide 376 in exon V causing an Asn-->Asp amino acid substitution. Although on the basis of its biochemical properties this variant was classified as G6PD Ferrara I, it has the same two mutations as G6PD A(-), which is common in American and African blacks, and as the sporadic Italian G6PD Matera. The mutation at nucleotide 202 was confirmed by NlaIII digestion of a polymerase chain reaction amplified DNA fragment spanning 109 bp of exon IV. The 109-bp mutated amplified sequence is not distinguishable from the normal sequence in single strand conformation polymorphism analysis.

Cloning, Molecular↗
PubMed1994

Immunochemical estimation of haemoglobin types in red blood cells by FACS analysis.

A fixation and permeabilization procedure using formaldehyde and acetone has been developed which allows immunostaining of intracellular haemoglobin for fluorescence activated cell sorter (FACS) analysis of erythrocytes. The treatment preserves antigenicity and light-scattering properties. Validation of the method was given by the correlation of F cell number in adults determined by FACS analysis with that assessed by microscopic examination of cell smears, and by the direct relationship between beta chain synthesis and intensity of beta chain/Hb A immunofluorescence within fetal erythrocyte samples known to vary in their beta chain/Hb A content. The procedure is rapid, non-subjective and sensitive, and makes analysis of haemoglobin content, type and distribution amongst red cell populations possible.

Acetone↗
PubMed1994

Biochemical and molecular characterization of a new sporadic glucose-6-phosphate dehydrogenase variant described in Italy: G6PD Modena.

A new glucose-6-phosphate dehydrogenase variant detected in an Italian man from the Po delta is described and designated as G6PD Modena. Biochemical characterization of the variant enzyme revealed an activity 21% of normal, a slow electrophoretic mobility, increased Km value for NADP, decreased Km value for G6P and a complete absence of NADPH inhibition, which could account for the apparently nonhaemolytic feature of this variant. The cloning and sequencing of the G6PD Modena allele showed a G-->C transition at nucleotide 844 in exon VIII causing a Asp-->His amino acid substitution. On the basis of biochemical characterization, G6PD Modena is classified as a genuine variant but it has the same mutation as G6PD Seattle-like.

Adult↗
PubMed1994

Detection of a major gene for heterocellular hereditary persistence of fetal hemoglobin after accounting for genetic modifiers.

"Heterocellular hereditary persistence of fetal hemoglobin" (HPFH) is the term used to describe the genetically determined persistence of fetal hemoglobin (Hb F) production into adult life, in the absence of any related hematological disorder. Whereas some forms are caused by mutations in the beta-globin gene cluster on chromosome 11, others segregate independently. While the latter are of particular interest with respect to the regulation of globin gene switching, it has not been possible to determine their chromosomal location, mainly because their mode of inheritance is not clear, but also because several other factors are known to modify Hb F production. We have examined a large Asian Indian pedigree which includes individuals with heterocellular HPFH associated with beta-thalassemia and/or alpha-thalassemia. Segregation analysis was conducted on the HPFH trait FC, defined to be the percentage of Hb F-containing cells (F-cells), using the class D regressive model. Our results provide evidence for the presence of a major gene, dominant or codominant, which controls the FC values with residual familial correlations. The major gene was detected when the effects of genetic modifiers, notably beta-thalassemia and the XmnI-G gamma polymorphism, are accounted for in the analysis. Linkage with the beta-globin gene cluster is excluded. The transmission of the FC values in this pedigree is informative enough to allow detection of linkage with an appropriate marker(s). The analytical approach outlined in this study, using simple regression to allow for genetic modifiers and thus allowing the mode of inheritance of a trait to be dissected out, may be useful as a model for segregation and linkage analyses of other complex phenotypes.

Adolescent↗
PubMed1993

Meiotic recombination in an Irish family with beta-thalassaemia.

Using the technique of allele-specific priming of the polymerase chain reaction (PCR), the C-T substitution in codon 39 was identified as the cause of beta-thalassaemia in an Irish family. Analysis of the restriction fragment length polymorphisms (RFLPs) in the beta-globin gene cluster established linkage of the beta-thalassaemia mutation to a particular beta-haplotype but indicated that a recombinational event had occurred in the paternal chromosome in the younger of two affected children. Non-paternity was excluded by DNA fingerprinting analysis with hypervariable minisatellite probes. This is the fourth case of recombination in the beta-globin gene cluster to be reported. The event has occurred 5' of the polymorphic RsaI site at position -550 bp upstream of the beta-globin gene mRNA Cap site, within the 9.1-kb region that has been shown to be a hot spot for recombination in the beta-globin gene cluster.

Base Sequence↗
PubMed1993

Prenatal sex determination from maternal peripheral blood using the polymerase chain reaction.

We have investigated the use of a nested polymerase chain reaction assay for the detection of a fetal-specific Y-chromosomal sequence (DYS14) from DNA extracted from unsorted maternal peripheral blood. Serial dilutions of male DNA into female cord blood DNA indicated that the assay could detect an equivalent of a single male cell in 300,000 female cells. The assay exhibited absolute specificity for male DNA with no amplification from a DNA panel obtained from 10 female cord blood samples. When used on DNA extracted from unsorted peripheral blood from a series of pregnant women, the predictive values of a positive test for a male fetus were 86%, 67% and 87% in the first, second and third trimesters, respectively. We have also demonstrated that retesting the samples allows the detection of a proportion of male-bearing pregnancies with a high degree of accuracy, in that all 15 women who gave positive signals in two consecutive amplifications had male fetuses. We have also applied the test at 8 weeks postpartum to eight women who had previously delivered male babies; no Y-specific signal could be detected in any of them, suggesting that most women have cleared their circulation of fetal cells by 8 weeks after parturition.

Base Sequence↗
PubMed1993

Alternative splicing of human G6PD messenger RNA in K562 cells but not in cultured erythroblasts.

The biochemical properties of glucose-6-phosphate dehydrogenase (G6PD) vary in different tissues, and different protein isoforms of the enzyme have been described. Alternative splicing of G6PD intron VII has been detected in transformed lymphoblasts, granulocytes and spermatocytes; the function of this mRNA species is still unknown. We developed a PCR for detecting alternatively spliced G6PD mRNA in K562 and in erythroblasts at different stage of maturation obtained from human peripheral BFU-E in order to evaluate a possible physiological role during erythroid maturation. Trace events of alternative splicing of G6PD intron VII sequences were observed in K562 cells but not in BFU-E-derived erythroid precursors; we consider this phenomenon a non-functional activity in the cells analysed.

Base Sequence↗
PubMed1993

Geographical variation in prevalence of hepatitis B virus DNA in HBsAg negative patients.

AIMS--To study the geographical variation of the prevalence of hepatitis B virus (HBV) DNA in hepatitis B surface antigen (HBsAg) negative subjects. METHODS--A nested polymerase chain reaction (PCR) assay was used to amplify the core region of HBV. The assay was able to detect 10 molecules of a full length HBV plasmid. RESULTS--When applied to HBsAg negative paraffin wax embedded liver samples from Italy, Hong Kong, and the United Kingdom, a geographical variation in the prevalence of HBV-DNA positivity was noted. Two of 18 (11%) of Italian samples and 2/29 (6.9%) of Hong Kong samples were positive for HBV-DNA while none of the 70 cases from the United Kingdom was positive by nested PCR. Contamination by plasmid DNA was excluded using a novel method based on heteroduplex formation. One HBV-DNA positive case had idiopathic chronic active hepatitis, but the diagnoses in the other three HBV-DNA positive cases did not suggest any aetiological connection between HBV-DNA positivity and liver pathology. CONCLUSIONS--HBV-DNA could be detected in the liver tissues of a proportion of HBsAg negative subjects. The prevalence of such cases is related to the endemic rate of a geographical region. The use of HBV PCR on paraffin wax embedded tissues will be valuable for future studies on the molecular epidemiology of HBV.

Base Sequence↗
PubMed1992

Hepatitis C virus and porphyria cutanea tarda: evidence of a strong association.

Porphyria cutanea tarda in human beings is believed to be due to reduced hepatic uroporphyrinogen decarboxylase activity. However, extrinsic factors such as alcohol abuse and drug intake are required for clinical manifestation of the disease. In addition to typical cutaneous lesions, patients with porphyria cutanea tarda usually have chronic liver disease and moderate iron overload. Of 74 Italian patients with porphyria cutanea tarda, hepatitis C virus antibodies were detected in 76% by enzyme-linked immunoassay and in 82% by recombinant immunoblot assay. Viral genome, studied with nested polymerase chain reaction, was found in the sera of 49 subjects--47 positive and 2 indeterminate on recombinant immunoblot assay. Five percent of the patients were HBsAg-positive, and about 40% had had past hepatitis B contacts. Alcohol abuse was present in 38%. Liver biopsies performed in 42 patients showed chronic persistent hepatitis in 7 patients, chronic active hepatitis in 22 patients, fibrosis in three patients and cirrhosis in 10 patients. Hepatitis C virus antibody was detected in 100% of patients with chronic active hepatitis and in about 80% of all other groups. Alcohol abuse was more frequent in patients with cirrhosis (80%) than in the other groups. In Italian patients with porphyria cutanea tarda, the prevalence of hepatitis C virus infection was very high, comparable to that in non-A, non-B hepatitis and high-risk patient groups. Hepatitis C virus is probably the main pathogenetic factor of the liver disease of patients with porphyria cutanea tarda.

Alcoholism↗
PubMed1992

CYP21/C4 gene organisation in Italian 21-hydroxylase deficiency families.

A total of 33 Italian 21-hydroxylase (21-OH) deficiency families were investigated using a combination of short and long range restriction mapping of the CYP21/C4 gene cluster. The analyses revealed that large-scale length polymorphism in this gene cluster strictly conformed to a compound variable number of tandem repeats (VNTR) plus insertion system with between one and four CYP21 + C4 units and seven BssHII restriction fragment length polymorphisms (RFLPs) (75 kb, 80 kb, 105 kb, 110 kb, 135 kb, 140 kb and 180 kb). A total of 9/66 disease haplotypes, but only 1/61 non-disease haplotypes, showed evidence of gene addition by exhibiting three or more CYP21 + C4 repeat units. Of these, two were identified in one 21-OH deficiency patient who has a total of eight CYP21 + C4 units, being homozygous for the HLA haplotype DR2 DQ2 B5 A28. This haplotype carries four CYP21 + C4 units, three of which contain CYP21A-like genes and one of which contains a CYP21B-like gene that presumably carries a pathological point mutation. Of the other gene addition haplotypes associated with 21-OH deficiency, four show three CYP21 + C4 units flanked by HLA-DR1 and HLA-B14 markers. Although such haplotypes have commonly been associated with non-classical 21-OH deficiency, three examples in the present study are unexpectedly found in two salt-wasting patients, who are respectively homozygous or heterozygous for this haplotype. Only 7/66 disease haplotypes showed evidence of a CYP21B gene deletion.

Adrenal Hyperplasia, Congenital↗