Search PubMed⌕ Search

Biomedical subjects

M Izquierdo

Publications and source records attributed to M Izquierdo.

At least 109 records · Page 6Linked to original sources
PubMed1989

Mutation mapping of the 2B5 ecdysone locus in Drosophila melanogaster reveals a long-distance controlling element.

Mutations at the Broad-Complex, a key gene triggering metamorphosis in Drosophila melanogaster, were mapped at the DNA level. The Broad-Complex includes two mutually complementing allelic classes, br and l(1)2Bc, both of which can associate to insertions at the same intron. Alterations spreading over 50 kilobases upstream from the transcription unit also disrupt br but not l(1)2Bc function.

Animals↗
PubMed1988

Selective T cell subset depletion with anti-CD4 and anti-CD8 intact ricin immunotoxins.

In the present study we have comparatively analysed the specific activity of a panel of immunotoxins (ITs) prepared by coupling Ricin to several monoclonal antibodies (MoAbs) directed against the CD3, CD4 and CD8 T cell membrane molecules. Peripheral blood and bone marrow mononuclear cells (PBMC and BMMC) were incubated with the different ITs for 2 h, in the presence of 0.1 M lactose, washed and subsequently stimulated with either phytohemagglutinin (PHA) or an anti-CD3 MoAb. Our results indicate that the proliferative response of PBMC to both stimuli was specifically inhibited (greater than 95%) by either anti-CD3 IT or a combination of anti-CD4 and CD8 ITs, at concentrations comparable to those previously used for ex vivo T cell depletion (300 ng/ml). When used individually at the same dose, anti-CD8 and anti-CD4 ITs inhibited the PHA-induced PBMC proliferative response 40 and 70% respectively. When either anti-CD4 or anti-CD8 IT-treated cells were activated with PHA and cultured for 14 days in the presence of IL-2, less than 2% of the blasts expressed the corresponding antigens as assessed by flow cytometry analysis. Similar results were observed when BMMC were treated with the different ITs. In contrast, the growth of CFU-GM was minimally affected (0-25% inhibition). Our data indicate that ITs directed against T cell subsets are highly active and specific reagents that may be potentially useful for pre-transplant bone marrow purging.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Defective interleukin 2 receptor expression is associated with the T cell disfunction subsequent to bone marrow transplantation.

In the present work we have used monoclonal antibodies (mAb) as probes to attempt a dissection of the mechanisms underlying the immunodeficiency subsequent to bone marrow transplantation (BMT). To this end we have studied 19 allogeneic BMT recipients, analyzing the proliferative response of peripheral blood mononuclear cells (PBMC) after activation with either phytohemagglutinin (PHA), anti-CD3 or anti-CD2 mAb. All patients presented normal proportions of CD2+ and CD3+ lymphocytes, as assessed by flow cytometry. Our results indicated that in most cases both CD2 and CD3-mediated activation pathways were inefficient to trigger normal T cell proliferation. The addition of exogenous interleukin 2 (IL2) did not restore in most cases the proliferative response, pointing out that additional defects contribute to the hyporesponsiveness. This was more evident in the group of patients studied during the first 6 months. To further dissect the T cell defect we analyzed the effect of a phorbol ester (phorbol myristate acetate, PMA), which activates protein kinase C, on the anti-CD3-induced response. Our data showed that PMA synergized with anti-CD3 similarly to exogenous IL2, and restored the proliferative response only in certain cases. The expression of IL2 receptors (CD25) as assessed by cytofluorimetry, after either PHA or anti-CD3 and PMA stimulation, was shown to be depressed, and the addition of IL2 did not restore it. Finally, we observed that the early increase of intracytoplasmic Ca2+ after anti-CD3 stimulation was comparable to that detected in normal PBMC. Altogether these results indicate that a diminished CD25 expression is associated with the T cell defect, and cannot apparently be attributed to an inability of the CD3 molecule to transduce early activation signals thus suggesting that either protein kinase C itself or an as yet undefined metabolic step preceding IL2 receptor expression is abnormal in variable proportions of T cells after BMT, and constitutes another manifestation of this complex immunodeficiency.

Antibodies, Monoclonal↗
PubMed1985

Chronic juvenile toxic epidemic syndrome.

The clinical manifestations in 21 children with chronic toxic epidemic syndrome (TES) and musculoskeletal manifestations were analysed and compared with those of the adult population. The sex ratio (2.5:1, F/M) was different from the one found in adults (6:1, F/M). The neuromuscular syndrome, the scleroderma-like picture, the pulmonary hypertension, and the Raynaud's phenomenon characteristic of TES were similar to those in adults but milder in children. The less severe vascular endothelial lesions found on microscopic examination might explain the better prognosis in this age group.

Adolescent↗
PubMed1984

Sequences isolated from a Drosophila early-ecdysone puff are expressed in rat liver.

We have studied the presence of a cloned fragment of DNA from Drosophila melanogaster in other organisms by means of nucleic acid hybridization analysis. The isolated region is localized in polytene chromosomes at the 63F subdivision. This region includes a puff that responds within minutes to ecdysone stimulation. We have found that 63F DNA from D. melanogaster hybridizes 'in situ' to both DNA and RNA from D. simulans, D. teissieri, and D. hydei. In all these species the isolated DNA remains associated with one early-ecdysone stimulated puff. The isolated Drosophila recombinant DNA is also complementary to polyadenylated RNA from foetal and adult rat liver but fails to hybridize to the nonpolyadenylated RNA classes from both sources and to polyadenylated RNA from rat mammary glands.

Animals↗
PubMed1984

Toxic epidemic syndrome: musculoskeletal manifestations.

The musculoskeletal manifestations of a new systemic disease that developed after toxic oil consumption are described. Clinically, it was characterized by the presence of arthralgias, sometimes arthritis, extensive muscle atrophy, severe neuropathy and a scleroderma-like skin involvement. Radiologically, different types of osteopenia could be seen in the absence of joint space narrowing or erosions. Neither hypertrophy, nor hyperplasia of synoviocytes were seen on microscopic examination. A non-necrotizing vasculitis and increase in fibrous tissue were observed at different levels.

Adolescent↗
PubMed1982

In situ immunofluorescent visualization of chromosomal transcripts in polytene chromosomes.

The induction and distribution of chromosomal transcripts in the polytene chromosomes of D. melanogaster and D. hydei has been investigated by indirect immunofluorescence using an antiserum directed against DNA/RNA hybrids. The fluorescence was intense and occurred in most of the chromosomal subdivisions when the chromosomes were exposed to denaturing conditions and then allowed to reanneal. The extent of hybrid formation depended both on the extent of DNA denaturation and on the maintenance of RNA integrity. Fluorescence was absent from chromosomes treated with pancreatic RNase before denaturation. The velocity of the chromosomal DNA/RNA hybridization reaction and the effects of the initiation inhibitor of RNA synthesis, DRB, suggest that in order to hybridize the RNA has to be located in its transcriptional compartment. Even though overall patterns of fluorescence seem to be similar during a developmental stage, variations were observed, particularly some correlated with puff induction after ecdysone stimulation.

Animals↗
PubMed1981

Isolation of a structural gene mapping to subregions 63F of Drosophila melanogaster and 90B of D. hydei polytene chromosomes.

We have isolated by molecular cloning techniques a structural gene that maps to subregion 63F of Drosophila melanogaster chromosome 3L. This locus being one of the early chromosomal targets for ecdysone stimulation, may be induced to puff by the hormone. The gene is on a plasmid vector and it has been designated as pDm 63F. This recombinant molecule also maps to the early ecdysone inducible subregion 90B of Drosophila hydei chromosome 4. The cytological inspection of large number of chromosomal sets after in situ hybridization of the cloned DNA, locates the cloned sequence between bands 63F 2-4 according to Bridges map. Similarly, in Drosophila hydei the cloned DNA maps between subdivisions 90B 2-4 according to Berendes' map. In situ hybridization of the pDm 63F cloned DNA, directed to the nascent RNA rather than to the DNA, shows two to three times more silver grains over the corresponding regions when puffed than in the resting stage. There are however quantitative differences attending to the transcriptional activity of homologous loci in both species. By RNA excess hybridization we have found that the cellular concentration of the 63F cloned mRNA is bout 2 times higher in hormone stimulated total larval tissues than in non-stimulated ones.

Animals↗
PubMed1981

[9p trisomy syndrome. Two new cases (author's transl)].

Two cases of trisomy 9p, are reported affecting different break points involving chromosome 9; one of them showed skeletal abnormalities of importance. An analysis of the two cases reported is done and some of the last hypothesis in order to determine genetical and clinical correlations of the syndrome are considered.

Abnormalities, Multiple↗
PubMed1980

Isolation and mapping of a cloned ribosomal protein gene of Drosophila melanogaster.

Molecular cloning techniques are particularly well suited to the study of gene organization in Drasophila melanogaster because recombinant DNA can easily be localized in the genome by in situ hybridization to salivary gland polytene chromosomes. We report here the isolation and preliminary characterization of a recombinant phage, designated C25, containing a bona fide D. melanogaster ribosomal protein gene. In situ hybridization demonstrates that this sequence maps to region 99D on chromosome 3.

Animals↗
PubMed1979

An analysis of cytoplasmic RNA populations in Drosophila melanogaster, Oregon R.

Nucleic acid reassociation methods were used to estimate the number of different polyadenylated RNA [poly (A) + RNA] sequences in the cytoplasm of whole Drosophila melanogaster at different stages of development and in the cytoplasm of cells of the L3 cell line. The number-average length (LN) of poly (A) + RNA from L3 cells is 1.4 kb, and the steady-state LN of the poly (A) tracts is 70 nucleotides. Analysis of RNA-driven reassociation with copy DNA shows that the poly (A) + RNA from L3 cells contains 5200 different sequences distributed in three abundance classes. The RNA forms hybrid duplexes with about 4.5% of single-copy Drosophila DNA, corresponding to 6500 sequences of 1.4 kb. The LN of poly (A) tracts present in whole embryos, larvae, pupae, and imagos is in each case close to 70 nucleotides. RNA-driven reassociation experiments show that poly (A) + RNA from these sources contains, respectively, 3500, greater than or equal to 4900, 6900, and greater than or equal to 4900 sequences. Cross-hybridization reactions show extensive homology between these RNA populations. All five poly (A) + RNA preparations contain a prominent component with a sedimentation coefficient of 13 and a size of 1.78 kb, which is shown to be the larger species of mitochondrial rRNA. This rRNA binds to oligo (dT) cellulose and serves as an efficient template for cDNA synthesis by reverse transcriptase. In RNA-driven reassociation experiments it behaves like an abundant mRNA.

Animals↗