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Biomedical subjects

D Oliva

Publications and source records attributed to D Oliva.

At least 19 recordsLinked to original sources
PubMed1992

Non-serotonergic 3H-ketanserin binding sites in human platelets: characteristics and interaction with calcium antagonists.

Here we report the identification of binding sites for 3H-ketanserin in human platelet membranes. At 4 degrees C, 3H-ketanserin binding is saturable (Bmax = 0.58 pmol/mg protein), rapid (equilibrium being attained within 20 min) and reversible. The kinetics of the association and dissociation curves are consistent with the existence of a single class of binding sites, as confirmed also by computer-assisted analysis of the saturation curve. Specific binding is increased by Ca2+ and Mg2+. 3H-ketanserin binding is inhibited by serotonin (Ki = 48.5 microM), unlabeled ketanserin (Ki = 3-15 nM), as well as by another antiserotonergic drug, methysergide (Ki = 32.6 microM). However, other selective 5-HT2 ligands, such as ritanserin, spiperone and cyproheptadine fail to interact with 3H-ketanserin binding. On the contrary, tetrabenzine, a monoamine depleting agent, when preincubated at 30 degrees C, did inhibit the specific binding completely. 3H-ketanserin specific binding is inhibited in a dose-dependent fashion by some calcium blocking agents, with different potencies: verapamil (Ki = 2.25 microM), diltiazem (Ki = 139 microM) and SIM6080, a new Ca(2+)-antagonist related to the phenylalkylamines (Ki = 5.22 microM). Flunarizine inhibited 3H-ketanserin specific binding only at relatively high concentrations (IC50 greater than 100 microM), while nitrendipine did not show any inhibitory effect up to 20 microM. The present evidence indicates that all the sites labeled by 3H-ketanserin at 4 degrees C might be coincident with the monoamino transporter identified in other systems, and that they might play a role in the modulation of platelet aggregation exerted by some calcium blocking agents.

Binding Sites↗
PubMed1991

Eicosanoid release and mepyramine, LTC4 and LTD4 binding in passively sensitized human lung parenchyma in vitro.

In vitro passive sensitization of human lung parenchyma with hyper-immune serum did not affect the release of prostaglandin D2 (PGD2) or leukotriene (LT)-like activity upon challenge with anti-IgE antibody with respect to control lung, despite a marked difference in IgE levels between control (C) and sensitized (S) tissue. Binding studies with [3H]LTC4, [3H]LTD4 and [3H]mepyramine (a histamine H1 antagonist) showed a statistically significant increase in the amount bound in sensitized vs control lung for [3H]mepyramine only. Contractile response to 5 x 10(-5) M histamine (H) in C and S lung parenchymal strips did not correlate with binding data. It is concluded that in vitro elevated IgE levels do not affect the interaction of sulfidopeptide leukotrienes with their putative receptors. As for the observed increase in [3H]mepyramine binding, this might not represent a true increase in histamine receptors on lung smooth muscle cells.

Animals↗
PubMed1991

Complete structure of the human gene encoding neuron-specific enolase.

At least three genes encode the different isoforms of the glycolytic enzyme enolase. We have isolated the gene for the human gamma- or neuron-specific enolase and determined the nucleotide sequence from upstream to the 5' end to beyond the polyadenylation site. The gene contains 12 exons distributed over 9213 nucleotides. Introns occur at positions identical to those reported for the homologous rat gene, as well as for the human alpha- or nonneuronal enolase gene, supporting the existence of a single ancestor for the members of this gene family. Primer extension analysis indicates that the gene has multiple start sites. The putative promoter region lacks canonical TATA and CAAT boxes, is very G + C-rich, and contains several potential regulatory sequences. Furthermore, an inverted Alu sequence is present approximately 572 nucleotides upstream of the major start site. A comparison of the 5'-flanking region of the human gamma-enolase gene with the same region of the rat gene revealed a high degree of sequence conservation.

Amino Acid Sequence↗
PubMed1991

Abnormal MRI signal in the rigid form of Huntington's disease.

Eighteen patients with Huntington's disease (HD) were examined with MRI. Eleven had the common hyperkinetic form, seven had the rigid variant. All seven patients with rigid HD had increased signal intensity in the neostriatum in intermediate and T2-weighted images. Only one hyperkinetic HD had similar findings. In all the other cases, signal abnormalities were questionable or absent. Histological differences that account for differences in signal intensity may therefore lie in the caudate nucleus and putamen. Age of onset may be important, since the rigid patients were younger. Follow up studies may help in understanding these signal differences.

Adolescent↗
PubMed1991

Endogenous opioids modulate neuronal survival in the developing avian ciliary ganglion.

Most studies on the trophic regulation of the normal neuronal competition for survival have focused on interactions between neurons and their target environment. However, it is also likely that trophic modulators are released from premotor inputs onto motoneurons. We have examined the developmental distribution of endogenous enkephalin-like immunoreactivity and the role that these endogenous opioid peptides play in normal neuronal degeneration. During the early portion of the normal cell death period, enkephalin-like immunoreactivity is highest within preganglionic cell bodies in the midbrain and their nerve terminals in the ciliary ganglion. Exogenous daily morphine administration to the chick embryo has previously been shown to delay most of the normal neuronal death in the ciliary ganglion (see Meriney et al., 1985). We hypothesized that opiate receptor activation increases the probability that ciliary ganglion neurons will survive their developmental competition and, further, that the endogenous opioid peptides in the ciliary ganglion normally modulate this competition. However, in our previous report (Meriney et al., 1985), we noted that daily administration of the antagonist naloxone to the chorioallantoic membrane did not significantly alter neuronal survival, as would have been expected if endogenous opioids were involved in regulating cell death. In contrast, in this report we show that three times daily application of naltrexone (a long-lasting opiate antagonist) significantly decreased neuronal survival among the ciliary ganglion cells, and that the surviving cells were not ultrastructurally different than neurons from controls of the same developmental stage. To control for toxic effects of naltrexone, we performed cell counts following naltrexone, we performed cell counts following naltrexone treatment in another population of cholinergic motoneurons (lumbar spinal motoneurons). In this population of cells, the total number of motoneurons remains unchanged following naltrexone treatment. To test for a specific toxic effect on the neurons of the ciliary ganglion, we generated a dose-response curve for toxicity in vitro and determined that naltrexone was not toxic over concentration ranges that are likely to exist in vivo. It appears, therefore, that a multiple daily antagonist application protocol blocks opiate receptors sufficiently in the ciliary ganglion to decrease an endogenous opiate influence significantly. We tested the possibility that endogenous opioids exert their effect by modifying transmission at peripheral and ganglionic synapses. In the generally accepted hypothesis, paralysis at the peripheral nerve-striated muscle synapse would rescue cells, while paralysis of ganglionic synapses would decrease survival. Iris neuromuscular junctions onto striated muscle cells were not blocked by opioids, but neuromuscular transmission in the smooth muscle of the choroid coat was blocked.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Structure of the human gene for alpha-enolase.

In mammals there are at least three isoforms of the glycolytic enzyme enolase encoded by three similar genes: alpha, beta and gamma. In this report we describe the isolation and characterization of the human alpha-enolase locus. The gene appears to exist as a single copy in the haploid genome and is composed of 12 exons distributed over more than 18,000 bases. The structure of this gene has a high degree of similarity to that of the human and rat gamma-enolase genes, with identical positions for all the intron regions. Primer extension and S1 nuclease protection experiments indicate that transcription is initiated at multiple sites. The putative promoter region, like that of other house-keeping genes, lacks canonical TATA and CAAT boxes, is extremely G + C-rich and contains several potential SP1 binding sites. Furthermore, various sequences similar to known regulatory elements were detected.

Base Sequence↗
PubMed1990

The gene for the muscle-specific enolase is on the short arm of human chromosome 17.

The human gene encoding the muscle-specific beta-enolase has been isolated. The beta-enolase gene was mapped to chromosome 17 by analysis of a panel of rodent-human somatic cell hybrids. The gene was further localized to the short arm and tentatively to the region 17pter-p11 by analysis of cell hybrids and transfectant cell lines carrying different portions of chromosome 17.

Blotting, Southern↗
PubMed1990

The human genome contains a single processed pseudogene for alpha enolase located on chromosome 1.

We have isolated and characterized human genomic clones containing an alpha enolase pseudogene which lacks introns and has the hallmarks of having been generated by reverse transcription. Two in-frame termination codons renders its coding region incapable of producing a functional protein. An Alu-like sequence is present in the region homologous to the 3' untranslated of the alpha enolase mRNA. Comparison of the two sequences shows that the pseudogene diverged from its functional counterpart about 14 million years ago and interestingly it is the only alpha enolase pseudogene present in the human genome. Chromosomal mapping locates the processed pseudogene to human chromosome 1, the same chromosome where the functional gene has been mapped.

Base Sequence↗
PubMed1990

Contractile and binding activities of structural analogues of LTC4 in the longitudinal muscle of guinea-pig ileum.

High affinity binding sites for LTC4 have been identified in various tissues, including guinea-pig ileal longitudinal muscle. More recently, it has been shown that LTC4 binds to non-receptor sites as well, particularly to glutathione transferases. In the present study, LTC4 and 9 chemically synthesized analogues, as well as the SRS-A antagonist FPL 55712 and S-decyl-glutathione, were tested for their ability to inhibit 3H-LTC4 binding in membranes from guinea-pig ileal longitudinal muscle and to affect the tone of the ileum in vitro. A significant correlation between binding and contractile activities was found for the LTC4 analogues and FPL 55712. However, S-decyl-glutathione, although possessing some affinity for LTC4 binding sites, was devoid of any effect on guinea-pig ileum tone at least up to 10(-5) M, thus indicating that these sites cannot be functional receptors, although they may represent other units involved in leukotriene action, e.g. uptake sites.

Animals↗
PubMed1989

Cloning, expression and sequence homologies of cDNA for human gamma enolase.

The nucleotide sequence of the human gamma-enolase mRNA was determined from recombinant cDNA clones. The sequence spans 2273 bp and includes the complete coding region of 1299 bp, a 5'-noncoding region of 74 bp and a 897-bp-long 3'-noncoding region containing a variant polyadenylation signal (ATTAAA). The deduced amino acid (aa) sequence is 433 aa long and shows a 97% similarity with rat gamma-enolase. Both the 5'- and 3'-untranslated regions are similar (82% and 68%, respectively) to the analogous regions of the rat gamma-enolase gene, suggesting that a strong selective pressure operates on noncoding segments of gamma-enolase mRNAs. The size of the gamma-enolase mRNA expressed in human brain is 2.4 kb. A crosshybridizing 1.5-kb message is detected in human skeletal muscle which may be derived from the beta-enolase-coding gene.

Amino Acid Sequence↗
PubMed1989

Occupational engagement of low-functioning individuals: extending the applicability of a computer-aided programme.

The present study addressed two questions concerning a computer-aided programme for supervising occupational activities for low-functioning individuals. The first question was about the possibility of using the programme for extended time periods. The second question concerned the viability of the programme for subjects who require physical prompting in addition to normal supervision (e.g. instructions and reinforcement). Three adolescents participated in the study. Two of them (who could perform under normal supervision) were selected for investigating the first question. The other subject (who required caretaker prompting) served for the second question. The results for the first two subjects showed that the computer-aided programme could easily ensure engagement in constructive activities for periods of about 30 min. The data for the third subject showed the establishment of moderate responding. The practical implications of the findings are discussed.

Adolescent↗
PubMed1989

The pharmacology of leukotrienes in human airways: in vitro and in vivo studies.

Immunological challenge of human lung parenchyma causes formation of arachidonate metabolites: prostaglandin D2 (PGD2) (70% of the formed mediators), leukotrienes E4 (LTE4) (15%) and D4 (LTD4) (10%). Leukotriene B4 (LTB4) was barely detectable (2%). Inhibition of PGD2 formation by indomethacin (15 microM) was approximately 90%, but was not accompanied by redistribution of arachidonate metabolism towards sulphidopeptide leukotrienes, as postulated for aspirin-sensitive asthma. Specific binding sites for leukotrienes C4 (LTC4) have been identified in membrane preparations of human bronchi. Binding of 3H-LTC4 is rapid (1 min) and quickly reversible following addition of excess. The sites are specific for LTC4 and competition curves fitted a two-site model. Moreover, clinical studies on specific endobronchial challenge of patients allergic to Dermatophagoides pteronyssinus, revealed narrowing of bronchial diameter and oedema of the bronchial mucosa; these symptoms were accompanied by an increase of immunoreactive-LTC4 and PGD2 present in the bronchial lavage fluids.

Asthma↗
PubMed1988

Isolation and characterization of a sea urchin hsp 70 gene segment.

Three clones containing Paracentrotus lividus sea urchin DNA sequences which cross-hybridize to Drosophila heat shock protein (hsp) 70 gene were isolated. The sequence arrangements in the three cloned DNA inserts were compared by restriction and cross-hybridization analysis. The results showed that they contain four different genes related to one Drosophila hsp 70 gene. One of these genes was subcloned, and two of the isolated fragments were shown to hybridize to genomic DNA and to RNA from heat-treated sea urchin embryo.

Animals↗