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Biomedical subjects

A Maresca

Publications and source records attributed to A Maresca.

14 recordsLinked to original sources
PubMed1990

Bronchial brushing and biopsy: a comparative evaluation in diagnosing visible bronchial lesions.

One hundred and forty patients underwent 142 brushings and conventional biopsies of suspected malignant lesions of the lung through a fibreoptic bronchoscope. Both samples were taken from the same area. One hundred and three patients showed positive results on brushing and 90 on biopsy. Thirty-nine diagnoses were negative on brushing and 52 on biopsy. A correct cell typing was obtained in 105 of 109 diagnoses of malignancy. Final diagnoses showed 118 malignant lesions and 22 benign conditions. False positives were respectively, 2 on brushing and 1 on biopsy, while false negatives were 17 on brushing and 30 on biopsy. Brushing showed higher sensitivity (85.5%) and accuracy (86.6%) than biopsy. A combination of the two techniques gives an accuracy rate of 94.3%.

Adult↗
PubMed1988

Tracheal reconstruction with jejunal loop autograft.

An experimental study on tracheal reconstruction using a jejunal loop autograft, is reported. Eight dogs divided into 2 groups have been used. In the first group the jejunal loop was prepared using a single vascular pedicle including both the artery and the vein and was revascularized with the superior thyroid artery and its collateral vein. In the second group the jejunal loop was prepared with two different vascular pedicles, revascularizing the artery with the superior thyroid artery and the vein with the jugular vein. In this group a sylastic T-tube was placed inside the loop. The procedure and preliminary results, are reported.

Animals↗
PubMed1987

Genomic organization of low copy number sequences that are associated with deca-satellite DNA in the monkey genome.

A previously described segment of African green monkey DNA (cloned in phage lambda MkA) contains deca-satellite linked to DNA sequences that are estimated to occur once per genome. Sequences homologous to the low copy number sequences in lambda MkA are also associated with species-specific satellite DNAs in the human and mouse genomes. A second clone, lambda Mk8, contains a monkey DNA region that is colinear and homologous to a portion of the low copy number sequences in lambda MkA, but no satellite sequences. The two cloned segments are markedly different starting at a point proximal to the satellite DNA region in lambda MkA. DNA-blotting experiments indicate that lambda Mk8 but not lambda MkA represents the typical genomic organization and that the low copy number segments occur only once per haploid genome. The data suggest that rearrangements such as deletions or inversions occurring in monkey cells account in part for the structure of lambda MkA. Additional rearrangements may have occurred during cloning in E. coli. This unique chromosomal region may be particularly susceptible to recombination.

Animals↗
PubMed1986

Isolation of low-copy-number sequences that neighbor satellite DNA in mammals.

To investigate the role of satellite DNA in eukaryotic genomes, we isolated from an African green monkey (Cercopithecus aethiops) genomic library cloned segments containing the previously described deca-satellite linked to low-copy-number genomic sequences. Three such clones were obtained. The low-copy-number sequences in the three clones do not cross-hybridize suggesting that they derive from different genomic loci. The structure of one of the clones, lambda MkA, is described in detail. Subcloned segments containing the low-copy-number sequences from lambda MkA anneal to monkey, human and mouse genomic DNA. The subcloned probes were used to select clones containing homologous sequences from a second, independent monkey library as well as from human and mouse genomic libraries. Several of the newly isolated monkey clones hybridized to probes containing the species-specific deca- and alpha-satellites, confirming the genomic association of the low-copy-number sequence in lambda MkA with satellite DNA. Moreover, several of the human and mouse clones hybridized to species-specific human and mouse satellite DNAs, respectively. These experiments indicate that the low-copy-number sequence in lambda MkA and its association with satellite DNA is conserved in primates and rodents.

Animals↗
PubMed1984

Continuous reorganization leads to extensive polymorphism in a monkey centromeric satellite.

Previously we reported the existence of a highly polymorphic satellite, deca-satellite, in the African green monkey genome; deca-satellite probe anneals to complex sets of repeated restriction endonuclease fragments that differ from individual to individual in the monkey population. Here we present experiments aimed at clarifying the structure and organization of deca-satellite sequences and investigating the mechanisms that generate the polymorphisms. Deca-satellite represents less than 1% of the monkey genome but the percentage varies from one monkey to another. The core sequence 5'-C-C-G-G within the ten base-pair deca-satellite repeat unit is well conserved and the central 5'-C-G is sometimes but not always methylated. Restriction endonuclease analysis with BamHI and EcoRI defines separate satellite domains that have evolved in an independent manner. In situ hybridization shows deca-satellite to be located at the centromeric regions of some but not all monkey chromosomes. This location is independently confirmed by a high frequency, in monkey libraries, of segments containing junctions between deca-satellite and alpha-satellite, the main monkey centromeric satellite. The total number of metaphase chromosomes that show centromeric grains after in situ hybridization with a deca-satellite probe varies from one monkey to another. Moreover, in situ hybridization to endoreduplicated diplochromosomes showed that deca-satellite is occasionally distributed asymmetrically on one or the other of the two pairs of sister chromatids in one diplochromosome. This indicates that major reorganization of the satellite can occur frequently in somatic cells. We discuss several possible mechanisms by which deca-satellite sequences could be either amplified or deleted during a single replicative cycle. Also, on the basis of the marked fluidity of deca-satellite abundance and organization and other well-known attributes of centromeric satellites, we suggest that the existence and maintenance of centromeric satellite rests on the role of the tandem repeats themselves and not on any particular nucleotide sequence, repeat length or organization.

Animals↗
PubMed1983

Deca-satellite: a highly polymorphic satellite that joins alpha-satellite in the African green monkey genome.

Three different cloned segments of African green monkey DNA that contain alpha-satellite sequences linked to a previously undescribed, distinct monkey satellite (called deca-satellite) are described here. The cloned segments were derived from a monkey DNA library in lambda Charon 4A that was constructed to select for junctions between alpha-satellite and other DNA sequences. The structure of the deca-satellite and of a junction between deca-satellite and alpha-satellite were studied by subcloning appropriate fragments of the original cloned segments and by sequence analysis. Deca-satellite has a ten base-pair repeat unit; the consensus sequence of the repeat units is 5' A-A-A-C-C-G-G-N-T-C. Sequences homologous to the deca-satellite are in the middle repeated class of genomic DNA. Analysis of the organization of deca-satellite sequences by digestion of total DNA with various restriction endonucleases and hybridization with a cloned deca-satellite probe revealed extensive polymorphism in the genomes of different individual monkeys but not among the tissues of one organism. These observations indicate that the arrangement of deca-satellite sequences is continually changing. An unusual alpha-satellite repeat unit occurs at a junction between the alpha-satellite and deca-satellite. It resembles the major baboon alpha-satellite more closely than it does monkey alpha-satellite and thereby provides evidence in favor of the "library" hypothesis for satellite evolution.

Animals↗
PubMed1976

Human alpha-fucosidase. Single residual enzymatic form in fucosidosis.

Four major forms of alpha-fucosidase (EC 3.2.1.51) activity were separated by isoelectrofocusing from sera of normal control individuals. All forms shifted towards less acidic pI values after neuraminidase treatment. In two patients affected with fucosidosis, only a single major acidic peak was observed and this was affected to a lesser degree by neuraminidase treatment. The kinetics of heat inactivation of the residual activity found in these two patients showed two decay rates while the controls showed only one rate. These data are considered in relation to the hypothesis of the existence of interconvertible thermolabile and thermostable forms of the enzyme which has been discussed in the preceeding paper. The residual alpha-fucosidase found in patients could be structurally altered so that its ability to form the thermostable higher molecular weight aggregates is impaired.

Adolescent↗