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Biomedical subjects

M Clementi

Publications and source records attributed to M Clementi.

At least 163 records · Page 9Linked to original sources
PubMed1992

Human immunodeficiency virus type 1 and hepatitis B virus transcription in peripheral blood lymphocytes from co-infected subjects.

The molecular characteristics of peripheral blood lymphocyte (PBL) infection by hepatitis B virus (HBV) were studied in human immunodeficiency virus type 1 (HIV-1) infected subjects using highly sensitive polymerase chain reaction (PCR) based techniques. DNA and RNA samples were purified from PBLs of HIV-1 infected individuals, regardless of their HBV serological status and assayed using PCR and reverse-transcription (RT) PCR, respectively. The data shown here are an extension of previous reports documenting HBV and HIV-1 co-infection of PBLs and indicate that transcriptionally active HBV infection of PBLs is detectable in a significant proportion of asymptomatic HIV-1 infected patients.

DNA, Viral↗
PubMed1992

Sequence analysis of the hepatitis B virus pre-C region in hepatocellular carcinoma [HCC] and nontumoral liver tissues from HCC patients.

We investigated whether replication-competent pre-C/C defective mutants of hepatitis B virus (HBV) are detectable in primary human hepatocellular carcinoma (HCC) tissues from patients of a geographic area endemic for such mutants. DNAs extracted from formalin-fixed paraffin-embedded HCC samples were checked for the presence of specific HBV DNA sequences using the polymerase chain reaction (PCR). Amplified pre-C regions from nine HCC samples were directly sequenced as were samples of nontumoral liver tissues from five of these patients. The data show that hypervariable distal pre-C sequences were present in all nine HCC samples; this high variability was dependent on point mutations, which led to amino acid substitutions in nearly all cases. Interestingly, seven of the nine HBV DNA-positive samples from HCC tissues (but not samples from peritumoral liver tissue) showed mutations leading to amino acid substitution at the level of a distal cysteine residue. No mutation generating a translationally defective pre-C/C region was detectable in the tumor samples. Otherwise, in four of the six nontumoral liver tissues available from the same patients, a pre-C sequence with an in-frame TAG stop codon was detectable, although in three cases as a component of mixed population.

Amino Acid Sequence↗
PubMed1992

Absolute quantitation of viremia in human immunodeficiency virus infection by competitive reverse transcription and polymerase chain reaction.

A competitive polymerase chain reaction (PCR)-based assay for the quantitative detection of human immunodeficiency virus type 1 (HIV-1) viremia was developed and optimized. This method consists of the reverse transcription and subsequent amplification in the same tube of two similar RNA templates, the wild-type template to be quantified and a known amount of the internally deleted synthetic template, both with identical primer recognition sites. The same strategy also proved to be useful in the quantitative assay of HIV-1-specific cellular transcripts and proviral DNA sequences from peripheral blood mononuclear cells by using competitor DNA. The method might be of interest in the study of the precise level of HIV-1 activity during the different clinical phases of the infection and in the simple, fast, and methodologically correct molecular investigation of patients treated with specific antiviral compounds.

Base Sequence↗
PubMed1992

Molecular profile of human immunodeficiency virus type 1 infection in symptomless patients and in patients with AIDS.

Recent molecular evidence indicates that active human immunodeficiency virus type 1 (HIV-1) infection is detectable in both symptomless and symptomatic infected patients. For this main reason, it has been pointed out that precise quantitative analysis of viral activity in vivo is necessary, firstly, for the pathogenetic investigation of the steps relevant to infection progression and, secondly, for better clinical management of HIV-1-infected patients. In this study, the presence of HIV-1 genomic RNA in plasma samples, specific HIV-1 transcripts in peripheral blood mononuclear cells, and proviral DNA sequences were assayed for 33 HIV-1-infected patients (including symptomless and symptomatic subjects) by using a competitive polymerase chain reaction method that allows quantitation of the RNA/DNA target sequences. The quantitative results obtained confirm that transcription of HIV-1 structural genes and complete viral replication occur in all the HIV-1-infected patients independently of the clinical stage. However, although sharp individual differences were detected, a high degree of correlation of the molecular parameters studied with both disease progression and a decrease in the number of CD4+ T lymphocytes was documented. Interestingly, despite the increasing viremia level associated with infection progression, the mean transcriptional activity of individual infected cells was found to be only moderately greater in AIDS patients than in asymptomatic infected subjects. In addition, it was noted that quantitation of HIV-1 genomic RNA in plasma samples and quantitation of specific HIV-1 transcripts in peripheral blood mononuclear cells appear to be more reliable and sensitive markers of viral activity than quantitative analysis of proviral HIV-1 sequences in peripheral lymphocytes.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Co-amplification of transcriptionally active epidermal growth factor receptor and ribosomal genes in the human hepatoma cell line Li7A.

A high level of expression of the functional product of the epidermal growth factor receptor (EGFR) gene was detected in the human hepatocarcinoma cell line Li7A and it was found to correlate with gene amplification. The karyotype was paratriploid, with 15 rearranged chromosomes, several of which contained abnormally banded regions (ABRs). The search for DNA sequences co-amplified with the EGFR gene, using the in-gel renaturation technique, allowed us to detect an amplified DNA band (La1) of about 30 kb. This DNA was used as a probe for in situ hybridization on chromosomes, to locate the amplified segment. In normal lymphocytes, the DNA of band La1 hybridized to chromosome regions in which repetitive DNAs are located, i.e. on juxtacentromeric regions, the site of alphoid and CCATT satellite DNA, and on the short arms of acrocentrics, the site of ribosomal RNA (RNR) genes. In Li7A cells, it hybridized to the same regions and, in addition, to several chromosome arms corresponding to ABRs. The same ABRs hybridized to EGFR and RNR probes, but neither Alu sequences nor various probes for other repetitive sequences were recognized. They also exhibited nucleolus organizer region staining characterizing functionally active (RNR) genes. It was concluded that transcriptionally active genes were co-amplified in the same ABRs, although they originated from different chromosomes, i.e. chromosome 7 for EGFR and acrocentrics for RNR genes.

Blotting, Northern↗
PubMed1991

Apparent CHARGE association and chromosome anomaly: chance or contiguous gene syndrome.

This report concerns 2 unrelated patients with apparent CHARGE association and a chromosome abnormality, resulting from different unbalanced familial translocations involving chromosomes 2 and 18 in one family, and chromosomes 3 and 22 in the other. Although the identification of two different chromosome abnormalities might be due to chance, the observation of a long arm deletion of chromosome 22 in patients 2 and of the frequent coexistence of CHARGE association and DiGeorge anomaly raise the possibility of a contiguous gene syndrome in at least some CHARGE cases.

Abnormalities, Multiple↗
PubMed1991

Detection of human immunodeficiency virus type 1 genomic RNA in plasma samples by reverse-transcription polymerase chain reaction.

An application of the polymerase chain reaction (PCR) to the direct detection of human immunodeficiency virus type 1 (HIV-1) viremia is described. The amplification of specific HIV-1 sequences of gag and env viral genes was carried out after the reverse-transcription of plasma samples (plasma RT-PCR) from seropositive subjects. The assay is faster and cheaper than detection of specific HIV-1 transcripts from peripheral blood mononuclear cells by RT-PCR. The data suggest that HIV-1 viremia is detectable by plasma RT-PCR in a large proportion of seropositive individuals.

Genes, env↗
PubMed1991

Levels of pre-S antigens and HBV DNA in sera from high and low viremic HBV carriers.

The biological and clinical significances of pre-S antigens and HBV replication were investigated. Some 125 sera, 28 from HBeAg and 97 from anti-HBe-positive HBsAg, carriers were studied. The aim was to verify whether pre-S antigens could be expressed in serum in complete absence of viremia. Pre-S proteins, determined by an enzyme immunoassay, were found in sera regardless of the presence of HBV DNA, as detected by spot-hybridization. The sera without detectable HBV DNA were investigated further by PCR using specific primers for the S and C regions of HBV. PCR analysis of samples revealed that 4 out of 5 HBeAg and 33 out of 41 (80.5%) anti-HBe positive sera contained HBV-amplified sequences of S and C regions. Pre-S antigen values correlated well with the amounts of HBV DNA in serum detected by PCR in anti-HBe-positive subjects with high titers of pre-S antigens (10(4)-10(6)). In addition, PCR highlighted the presence of HBV DNA sequences in 8 out of 17 (47.1%) pre-S-negative HBsAg-positive sera.

Antibodies, Monoclonal↗
PubMed1991

Linkage analysis of neurofibromatosis type 1. Study of a homogeneous North Italian population with five DNA markers of chromosome 17.

The authors report the results of a genetic analysis performed in 34 neurofibromatosis type 1 (NF1) Italian families using five loci tightly linked to NF1: D17S33, D17S82, D17S83, D17S37, and D17S36. A two-point linkage analysis was performed with the LINKAGE and the CRI-MAP programs. The map of the region was constructed using the MAP90 program. Data from the present study lend further support to evidence that all NF1 mutations are allelic and that the NF1 locus resides in the proximal region of chromosome 17q. Close linkage of NF1 to all the markers was found. Two of them, namely D17S82 and D17S83, showed the highest linkage with a value of 0 recombination frequency and lod scores of 3.77 and 4.02, respectively. The best map found is D17S33-D17S82-NF1-D17S83-D17S37-D17S36+ ++. The authors stress that knowledge of precise order is essential; if D17S82 and D17S83 are proved to flank the NF1 gene, they allow an acceptable presymptomatic diagnosis in informative families.

Chromosomes, Human, Pair 17↗
PubMed1991

A single-step DNA extraction procedure for the detection of serum hepatitis B virus sequences by the polymerase chain reaction.

A rapid single-step procedure for the isolation of low molecular weight DNA using guanidinium thiocyanate and phenol as protein denaturants is described and applied for the detection of specific hepatitis B virus (HBV) DNA sequences from serum samples by the polymerase chain reaction (PCR). The novel technique is efficient and, when compared to the standard proteinase K/phenol/chloroform method has the advantage of being faster and easily adaptable to the routine processing of a high number of clinical samples by PCR and spot hybridization techniques.

Base Sequence↗
PubMed1991

Detection of human immunodeficiency virus type 1 transcripts in peripheral blood lymphocytes by the polymerase chain reaction.

A simplified application of the polymerase chain reaction (PCR) to the routine detection of human immunodeficiency virus type 1 (HIV-1) transcripts from peripheral lymphocytes of infected subjects is described. This technique is simpler than previously described assays and was shown to be highly sensitive after ethidium bromide staining of polyacrylamide gel electrophoresis of amplified material. The method can be used for the virologic evaluation of HIV-1-infected subjects, thus allowing early identification of seropositive patients with signs of active infection.

Cell Line↗
PubMed1991

Growth and metabolic responses in low-birth-weight infants fed human milk fortified with human milk protein or with a bovine milk protein preparation.

Unfortified human milk does not normally provide enough protein to secure maximal growth in low-body-weight (LBW) infants. Due to the practical difficulties in obtaining human milk protein (HMP), a bovine milk protein preparation (BMP) was designed by computer calculation to contain as close as possible the amino acid composition of the nutritionally available human milk proteins. Twenty-one AGA, LBW infants (BW of 1,180 to 1,600 g, GA of 27 to 33 weeks) were randomly assigned to be fed HM enriched either with HMP (9 infants) or BMP (12 infants). When full volume intake (170 ml/kg/day) was reached, the protein intakes were 3.6 +/- 0.5 and 3.3 +/- 0.3 g/kg/day, respectively, in the two diet groups. During the study period of 24 days, the infants achieved intrauterine or better weight gains: 32.9 +/- 3.3 g/day (17.7 +/- 1.9 g/kg/day) in the HMP group and 34.7 +/- 7.3 g/day (18.3 +/- 3.5 g/kg/day) in the BMP group. Serum urea nitrogen, acid-base status, and albumin values were normal and similar in both groups of infants. Plasma concentrations of total essential and total amino acids at the end of the study were 3,999 and 1,539 mumol/L and 3,899 and 1,422 mumol/L in the HMP and the BMP groups, respectively. The concentrations of all individual plasma amino acids were similar in both feeding groups. These results show that feeding human milk fortified with a modified bovine milk protein preparation produces satisfactory growth and a plasma amino acid profile similar to that found in LBW infants fed exclusively human milk protein at similar intakes.

Acid-Base Equilibrium↗
PubMed1991

[Surfactant and ambroxol in the therapy of idiopathic respiratory syndrome in newborn infants].

The Authors have carried out a study on 30 newborns, affected by idiopathic respiratory distress syndrome (IRDS), divided into 3 statistically comparable groups, treated, in addition to mechanical ventilation, respectively with Tokio-Akita (TA) surfactant, placebo (both by endotracheal administration) and ambroxol given by intravenous infusion. The clinical evolution of the three groups was studied, above all as related to mortality, ventilation length, oxygen need, immediate and successive pulmonary complications and cerebral haemorrhage. Mortality was lower in the group treated with ambroxol, while the ventilation length, the average insufflation pressure and the oxygen need were lower in the group treated with surfactant, compared with the other two groups. Pulmonary complications were present only in the group treated with placebo and ambroxol, whereas cerebral haemorrhage rate is higher in the group treated with surfactant. On the basis of the results achieved, some important observations are suggested and possible aetiological therapies of IRDS are formulated.

Ambroxol↗
PubMed1990

Neonatal growth patterns in a population of consecutively born Down syndrome children.

Percentile charts of neonatal length, weight, head circumference, and weight/length squared have been constructed using data based on 688 consecutive newborn infants with Down Syndrome and 6,890 normal newborn infants (control group) registered in the congenital malformation registers of North-East Italy and the Emilia-Romagna Region. All percentiles of growth variables are lower in Down syndrome than in the control infants, except for the weight/length2 percentiles, suggesting that growth in Down syndrome is prenatally reduced; overweight begins after birth.

Body Height↗
PubMed1990

Growth-factor independence of a new differentiated hepatitis B virus DNA-negative human hepatoma cell line.

The establishment of a new, differentiated, hepatitis B virus DNA-negative, human hepatoma cell line (named PLC/AN/2) is described. Neoplastic liver tissue was obtained during hepatectomy in an HBsAg-negative man. The established cell line is negative for alpha-fetoprotein and carcinoembryonic antigen; it has retained in vitro some of the differentiated functions of normal hepatocytes. Additionally, it presents a distinctive rearrangement (translocation) at the long arm of chromosome 4. The high degree of independence from serum growth factor requirements appears to be a major in vitro characteristic of PLC/AN/2 cells, making them a suitable model system for the more precise definition of the human hepatocellular carcinoma phenotype, including mechanisms of growth control.

Carcinoma, Hepatocellular↗
PubMed1990

Neurofibromatosis-1: a maximum likelihood estimation of mutation rate.

Methods of classical segregation analysis were applied to a sample of 129 sibships with one or more individuals affected by neurofibromatosis-1 (NF-1). The sample consists only of subjects with NF-1; all the probands had been referred for genetic counselling because of café-au-lait spots, and a diagnostic protocol was invariably applied. No deviation from the segregation ratio expected for a fully penetrant Mendelian dominant gene was observed. A maximum likelihood estimate of the proportion of sporadic cases was obtained, and the mutation rate was estimated to be 6.5 x 10(-5) gametes per generation (95% CI 5.0-8.1).

Adult↗
PubMed1989

Expression of high- and low-affinity epidermal growth factor receptors in human hepatoma cell lines.

Data are presented from a comparative research on expression of epidermal growth factor (EGF) receptors and response to EGF of six independently established cell lines derived from human hepatoma. These lines differ in terms of the degree of differentiation, presence of hepatitis B virus (HBV) DNA copies in integrated form and expression of HBV genes. Our results indicate differential expression of membrane EGF receptors and differential response to EGF under serum- and hormone-free culture conditions. Furthermore, a significant difference in affinity could be detected between EGF receptors of the two highly dedifferentiated cell lines (HA22T/VGH and Li7A) whose replication is inhibited by EGF concentrations capable of stimulating more differentiated phenotypes.

Blotting, Southern↗