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Biomedical subjects

A Cuadrado

Publications and source records attributed to A Cuadrado.

At least 37 records · Page 2Linked to original sources
PubMed1999

Type 3 iodothyronine deiodinase is selectively expressed in areas related to sexual differentiation in the newborn rat brain.

Thyroid hormone (T4 and T3) concentrations in target tissues are greatly influenced by the activity of iodothyronine deiodinases. Type 1 and 2 deiodinases generate T3 from T4, while deiodinase type 3 (D3) transforms T4 and T3 to inactive metabolites. Coordination of the expression and activity of these enzymes is postulated to play an important role in physiology and development, making it possible that individual cells and tissues regulate the concentrations of the active hormone according to specific needs. We have analyzed the expression of D3 in the neonatal rat brain by in situ hybridization using a specific 35S-labelled riboprobe. At postnatal day 0 D3 transcripts were unexpectedly found to be selectively expressed in areas involved in sexual differentiation of the brain such as the bed nucleus of the stria terminalis and preoptic nuclei. Expression in these areas was transient and was no longer observed at postnatal day 10. These observations suggest that D3 expression is linked to the early mechanism determining sexual function and behavior.

Animals↗
PubMed1998

Activation of Akt/protein kinase B by G protein-coupled receptors. A role for alpha and beta gamma subunits of heterotrimeric G proteins acting through phosphatidylinositol-3-OH kinasegamma.

The serine/threonine protein kinase Akt has recently been shown to be implicated in the pathway leading to cell survival in response to serum and growth factors in a variety of cellular systems. However, the existence of a biochemical route connecting this kinase to the large family of receptors that signal through heterotrimeric G proteins is yet to be explored. In this study, we set out to investigate whether GTP-binding protein (G protein)-coupled receptors (GPCRs) can stimulate Akt activity and survival pathways and, if so, to define the mechanism(s) whereby this class of cell surface receptors could regulate Akt function. Using ectopic expression of GPCRs in COS-7 cells as a model, we have observed that both m1 and m2 muscarinic acetylcholine receptors, representative of those GPCRs coupled to Gq and Gi proteins, respectively, can readily activate an epitope-tagged form of Akt kinase and prevent UV-induced apoptosis. We have also found that the pathway connecting G proteins to Akt implicates signals emanating from Galphaq, Galphai, and beta gamma dimers, but not from Galphas or Galpha12, in each case acting through a pathway that involves a phosphatidylinositol-3-OH kinase activity. Moreover, our findings suggest a role for a novel beta gamma-sensitive complex, p101.phosphatidylinositol-3-OH kinase-gamma, in the transduction of signals leading to Akt stimulation and cell survival by GPCRs and open new avenues for research on the function of the large family of G protein-linked receptors in the regulation of anti-apoptotic pathways.

Animals↗
PubMed1998

The chromosomal organization of simple sequence repeats in wheat and rye genomes.

The physical distribution of ten simple-sequence repeated DNA motifs (SSRs) was studied on chromosomes of bread wheat, rye and hexaploid triticale. Oligomers with repeated di-, tri- or tetra-nucleotide motifs were used as probes for fluorescence in situ hybridization to root-tip metaphase and anther pachytene chromosomes. All motifs showed dispersed hybridization signals of varying strengths on all chromosomes. In addition, the motifs (AG)12, (CAT)5, (AAG)5, (GCC)5 and, in particular, (GACA)4 hybridized strongly to pericentromeric and multiple intercalary sites on the B genome chromosomes and on chromosome 4A of wheat, giving diagnostic patterns that resembled N-banding. In rye, all chromosomes showed strong hybridization of (GACA)4 at many intercalary sites that did not correspond to any other known banding pattern, but allowed identification of all R genome chromosome arms. Overall, SSR hybridization signals were found in related chromosome positions independently of the motif used and showed remarkably similar distribution patterns in wheat and rye, indicating the special role of SSRs in chromosome organization as a possible ancient genomic component of the tribe Triticeae (Gramineae).

Base Sequence↗
PubMed1998

Replication of 5 S ribosomal genes precedes the appearance of early nuclear replication complexes.

The present work shows that replication of the 5 S ribosomal genes differs in time and 3'deoxyadenosine sensitivity from replication of other nuclear genes, in Allium cepa L. root meristems. Fluorescence in situ hybridization with the pTa794 DNA probe which contains a complete 410 bp 5 S gene from Triticum aestivum allowed to detect four clusters of 5 S genes in these diploid cells (2n = 16), two of them in the short arm of the smallest metacentric chromosomal pair 7. Replication of the 5 S ribosomal genes occurred very early in interphase, as discerned by their resolution as doubled spots only two hours after interphase was initiated in synchronous binucleate cells. Codetection of nuclear replication (by immunodetection of 5-bromo-2'-deoxyuridine incorporation) showed that the replication of the 5 S ribosomal genes occurred before any incorporation of 5-bromo-2'deoxyuridine could be detected in the nuclei. The earliest Br-DNA detected in these cells followed a radial pattern from different foci apparently dispersed along some chromosomal arms. These structures seem to represent early replication complexes, as a result of the displacement of multiple DNA forks from the foci known as pre-replication complexes where the replication machinery of the earliest replicating genes assembles. No consistent positional correlation existed between the formation of the early replication complexes and the already replicated 5 S ribosomal clusters. Finally, nuclear replication but not that of the 5 S genes was prevented by 3'deoxyadenosine, and the earliest replicating 5 S ribosomal gene cluster differed in both sister nuclei resulting from the segregation of one single chromosome in anaphase.

Cell Nucleus↗
PubMed1998

Multiple locations of the rDNA sites in holocentric chromosomes of Rhynchospora (Cyperaceae).

Several cytogenetic studies have shown that representatives of the family Cyperaceae have holocentric chromosomes. Despite their interesting chromosome morphology, the chromosome organization has not been studied. This paper reports on the number and distribution of 18S-5.8S-26S ribosomal RNA sites by fluorescence in situ hybridization in eight Brazilian species of Rhynchospora. The signal of the rDNA probe was always localized in the telomeric regions. A high degree of variation was observed in the number of labelled sites, ranging from 4-8 in karyotypes with 2n = 10 to 30 sites in a karyotype with 50 chromosomes. It is possible that the same mechanism involved in the multiplication of these regions in organisms with monocentric chromosomes also plays a role in the polymorphism observed in holocentric chromosomes of Rhynchospora. An interesting feature of most hybridization sites was their diffuse state observed through to early metaphase. The decondensed state probably reflects the later transcription of this region during the cell cycle.

Chromosome Mapping↗
PubMed1998

Propofol concentrations in whole blood: influence of anticoagulants and storage time.

Blood samples for propofol determination are collected with oxalate, heparin and EDTA, but we have not found any study comparing the influence of those anticoagulants on propofol concentrations. This study was carried out on 50 samples from patients taking propofol for anesthesia or cerebral protection. First, 26 samples were simultaneously collected into tubes containing lithium heparin or sodium fluoride potassium oxalate as anticoagulant. In a second investigation, 24 samples were simultaneously collected into tubes containing heparin or EDTA. Propofol was assayed by HPLC 2 days after sampling and 2 weeks later. In the first assay, propofol concentration in samples collected with heparin were similar to those collected with oxalate (3.65 +/- 3.50 vs. 3.62 +/- 3.49 mg/l, ns) or EDTA (3.89 +/- 2.58 vs. 3.84 +/- 2.67 mg/L, ns). After storing for 2 weeks at 4 degrees C, propofol concentrations were slightly but insignificantly higher than in the first assay in samples collected with heparin (3.58 +/- 3.24 vs. 3.40 +/- 2.92 mg/l, ns), slightly higher in samples with oxalate (3.86 +/- 3.49 vs. 3.62 +/- 3.49 mg/l, p = 0.06), and slightly but significantly lower in samples with EDTA (3.63 +/- 2.67 vs. 3.84 +/- 2.67 mg/l, p < 0.05). It is concluded that the three anticoagulants used in this study seem to be suitable for determination of propofol concentration in whole blood, and that the stability of propofol concentration when samples are stored at 4 degrees C for up 2 weeks is acceptable.

Anticoagulants↗
PubMed1997

Vigabatrin serum concentration to dosage ratio: influence of age and associated antiepileptic drugs.

The relationship between the ratio of vigabatrin concentration to dosage (VGB C/D) and both patient age and the presence of other antiepileptic drugs (AEDs) was analyzed retrospectively by bivariate and multivariate methods in 179 patients with epilepsy (114 children and 65 adults). Of the 179 patients, 33 received VGB alone (30 children and 3 adults) and 146 received VGB with other AEDs (84 children and 62 adults). Vigabatrin trough steady-state serum concentration correlated better with VGB dosage in milligrams per kilogram than the dosage in milligrams in children (r = 0.62 vs. r = 0.17, P < 0.001) but not in adults (r = 0.51 vs. r = 0.49, NS). The correlation between milligrams per kilogram and serum concentration of VGB was greater in children on monotherapy (r = 0.83) than in those on polytherapy (r = 0.46). Vigabatrin C/D ratio increased significantly with age (r = 0.51, P < 0.001), being lower in children than in adults both by Student's t-test (0.087 +/- 0.039 vs. 0.128 +/- 0.057, mean +/- SD, P < 0.001) and by two-way analysis of variance when controlling for other AEDs (P < 0.001). Inducing AEDs seemed to increase VGB C/D ratio in the bivariate tests, but this influence decreased and even disappeared if patient age was considered in the multivariate analysis. However, the increase in VGB C/D ratio with VPA serum concentration (r = 0.46, P < 0.001) was confirmed by multiple regression including age (P < 0.001). Intrapatient variability of VGB C/D ratio was 29 +/- 18%. It was concluded that trough steady state VGB serum concentration may be more predictable in children based on the milligrams per kilogram dosage than on the milligram dosage, and that the influence of patient age should be considered if the VGB C/D ratio is used to estimate patient compliance.

Adolescent↗
PubMed1997

Distribution of highly repeated DNA sequences in species of the genus Secale.

The presence and distribution of the most important highly repetitive DNA sequences of rye in cultivated and wild species of the genus Secale were investigated using fluorescence in situ hybridization. Accurate identification of individual chromosomes in the most commonly recognized species or subspecies of the genus Secale (S. cereale, S. ancestrale, S. segetale, S. afghanicum, S. dighoricum, S. montanum, S. montanum ssp. kuprijanovii, S. africanum, S. anatolicum, S. vavilovii, and S. silvestre) was achieved using three highly repetitive rye DNA sequences (probes pSc119.2, pSc74, and pSc34) and the 5S ribosomal DNA sequence pTa794. It is difficult to superimpose trends in the complexity of repetitive DNA during the evolution of the genus on conclusions from other cytogenetic and morphological assays. However, there are two clear groups. The first comprises the self-pollinated annuals S. silvestre and S. vavilovii that have few repeated nucleotide sequences of the main families of 120 and 480 bp. The second group presents amplification and interstitialization of the repeated nucleotide sequences and includes the perennials S. montanum, S. anatolicum, S. africanum, and S. kuprijanovii, as well as the annual and open-pollinated species S. cereale and its related weedy forms. The appearance of a new locus for 5S rRNA in S. cereale and S. ancestrale suggests that cultivated ryes evolved from this wild weedy species.

Biological Evolution↗
PubMed1997

Competence for nuclear replication and the NOR-chromosomes of Allium cepa L.

Autotetraploid (4n = 32) cells were induced in Allium cepa L. root meristems by successively treating with a multipolarizing agent in anaphase (carbetamide) and an inhibitor of cell plate formation in telophase (caffeine). This treatment produced cells with their 32 chromosomes distributed in more than two nuclei. During G1, one of the nuclei in the resulting trinucleate cells had a DNA content which was equivalent to an average of 16 chromosomes, while the other 16 chromosomes were randomly distributed in two aneuploid nuclei. In the set of 16 chromosomes forming the onion diploid complement, there are 4 NOR-chromosomes and 5 chromosomes carrying DNA domains providing a nucleus with the competence to replicate, as previously shown. Expected probabilities derived from the different possible models for cosegregation of both kinds of chromosomes in the two aneuploid nuclei of the trinucleate cells were estimated by a computer simulation. These expected values were compared with the recorded frequencies of aneuploid nuclei which were able to organize a nucleolus and to respond to inducers of replication. The present data are compatible with the existence of sequences providing a nucleus with the competence to replicate in three out of the four NOR-bearing chromosomes, as well as in two other chromosomes of this diploid complement. The scarcity of chromosomes bearing early origins able to initiate replication in a nucleus is a striking feature of this huge onion genome.

Allium↗
PubMed1996

Physical mapping of repetitive DNA sequences and 5S and 18S-26S rDNA in five wild species of the genus Hordeum.

The genetic relationships between several wild species and subspecies of the genus Hordeum were assessed using fluorescence in situ hybridization (FISH). Plant material included natural populations of wild barley growing in Spain of the annual species, H. marinum ssp. marinum (2n = 14) and gussoneanum (2n = 14), and H. murinum ssp. murinum (2n = 28), and leporinum (2n = 28) and the perennial species H. bulbosum (2n = 14) and H. secalinum (2n = 28), plus the South American perennial species H. chilense (2n = 14). FISH was used to locate the chromosomal sites of two rDNA multigene families 5S and 18S-26S (pTa71 and pTa794) and three repetitive DNA sequences (pSc119.2, pAs1 and pHch950) isolated from different species and genera. The seven chromosomes of the diploid species were readily distinguished by their external morphology and hybridization patterns to pTa71, pTa794, pSc119.2 and pAs1. These DNA probes were also useful for the identification of homologous chromosomes and in differentiating these from unidentified chromosomes in the tetraploid taxa. The use of the probe pHch950 permitted intergenomic differentiation in tetraploids and supports the diphyletic origin of H. murinum and H. secalinum. The in situ experiments yielded the following conclusions: (1) differences between the sub-species marinum and gussoneanum; (2) close relationships between the subspecies murinum and leporinum; and (3) major differences in physical mapping between H. bulbosum and the remaining taxa. The genomic and phylogenetic relationships between taxa, as inferred from the results, are discussed.

Chromosome Mapping↗
PubMed1996

Nucleolar organizer expression in Allium cepa L. chromosomes.

Roots from Allium cepa L. (cv. Francesa) bulbs in which a maximum of two nucleoli per nucleus developed were selected for this study. Five rDNA clusters were detected by fluorescent in situ hybridization on chromosomal squashes (2n = 16) with a rhodamine-labelled wheat rDNA repeat. The rDNA clusters were located on four chromosomes: the largest cluster occurred on the small arm of a single homologue of the smallest pair 8. Its homologue showed two different small rDNA clusters, one near each telomere. The two homologues of the satellited chromosomes 6 also showed different rDNA contents, which were intermediate to those found in pair 8. The same five well-differentiated hybridization signals were observed in interphase cells that were inactive in transcription because they were in dormant roots, or in proliferating ones in which the synthesis of the large rRNA precursor was prevented. After multipolarizing agent was applied in anaphase followed by inhibition of cytokinesis, multinucleate autotetraploid cells were formed, which often contained more than four nucleoli. Thus, at least two of the three nucleolar organizer regions that consistently failed to develop a nucleolus in normal mononucleate cells were capable of developing nucleoli when segregated into different nuclei in multinucleate cells.

Chromosome Mapping↗
PubMed1995

Fluorescent in situ hybridization and C-banding analyses of highly repetitive DNA sequences in the heterochromatin of rye (Secale montanum Guss.) and wheat incorporating S. montanum chromosome segments.

The molecular characterization of C-banded regions of Secale montanum Guss. by means of in situ hybridization was performed in order to provide new information about their chromosome structure relative to cultivated rye, Secale cereale L. Accurate identification of individual chromosomes was achieved using simultaneous and (or) successive fluorescent in situ hybridization (FISH) and C-banding. FISH identification was performed using total rye DNA, three highly repetitive rye DNA sequences (pSc119.2, pSc74, and pSc34), and the ribosomal RNA probes pTa71 (18S, 5.8S, and 26S rDNA) and pTa794 (5S rDNA). FISH was also used to identify the chromosome segment involved in two spontaneous translocation lines recovered from a 'Chinese Spring'--S. montanum wheat-rye addition line. FISH analysis revealed the exact translocation breakpoints and allowed the identification of the transferred rye segments. The value of this type of analysis is discussed.

Chromosome Banding↗
PubMed1995

[Surgery for the repair of renal arteriovenous fistula and its hemodynamic impact].

The case of a 42-year-old woman with an arteriovenous fistula on the left kidney is described. Twenty-six years before presentation, a percutaneous renal biopsy had been obtained. The patient presented with arterial hypertension, angina and dyspnea. We studied the hemodynamic parameters before and after surgical repair of the fistula. Pulmonary artery pressure was very high but fell to normal after surgery, indicating that the fistula was responsible for hemodynamic complications that increased the level of surgical risk.

Adult↗
PubMed1994

Uneven distribution of protein kinase C-alpha and -beta isozymes in human sarcomas and carcinomas.

Protein kinase C (PKC) represents a family of structurally related Ser/Tre kinases which are involved in mitogenic signalling and may contribute to human neoplasia. To address this issue, the messenger RNA and protein levels of PKC isoenzymes alpha and beta were analyzed in several human sarcoma- and carcinoma-derived cell lines. Carcinomas contained low or undetectable levels of either PKC-alpha or PKC-beta. Sarcomas exhibited similar or increased PKC expression compared to human diploid fibroblasts. Moreover, sarcoma cell lines expressing one PKC isoform did not contain detectable levels of the other. When PKC was depleted from the tumor cells, we observed that the PKC overexpressing sarcomas had reduced their malignant properties as determined by their ability to grow in semisolid medium. In addition, epidermal growth factor-stimulated and erbB2-transformed fibroblasts exhibited enhanced cell growth in the absence of PKC. We propose a model for the effect of PKC as a negative regulator of proliferation in epithelial cells and a growth promoter in fibroblasts.

Amino Acid Sequence↗
PubMed1994

Mapping and organization of highly-repeated DNA sequences by means of simultaneous and sequential FISH and C-banding in 6x-triticale.

Three families of highly repeated sequences from rye and the rRNA multigenes (NOR and 5S) have been mapped by FISH and C-banding, in chromosomes of triticale. The pSc119.2 probe showed interstitial hybridization in chromosome arms 1RS, 1RL, 4RL, 5RL, 6RS, 6RL, 7RS and 7RL, and is very effective for chromosome identification of rye chromosomes in triticale. This sequence also hybridizes to the 4A, 5A and the seven B-genome wheat chromosomes. Simultaneous hybridization with the pSc119.2 and pTa794 (5S rRNA) is very useful to distinguish the metacentric chromosomes 2R and 3R. The pSc74 probe appears at interstitial sites in the long arm of the most heterobrachial chromosomes (5R and 6R). The three repetitive sequences of 120 bp, 480 bp, and 610 bp hybridize to telomeric regions in rye chromosomes. Different arrangements and complex organizations consisting of arrays of three or more family sequences were found. The results demonstrate a great variation in the relative arrangement of the repetitive sequences in the telomeres of the rye chromosomes. There were quantitative differences in each cytological marker between triticale lines in both in situ labelling and C-banding, probably as the result of differences in the number and/or kind of repeat sequence.

Chromosome Banding↗
PubMed1994

Activation of type D phospholipase by serum stimulation and ras-induced transformation in NIH3T3 cells.

Mitogenic stimulation of NIH3T3 fibroblasts with growth factors or ras oncogenes is associated with an increase in the levels of phosphorylcholine and diacylglycerol. Both metabolites could be generated as a result of direct activation of a phosphatidylcholine-specific phospholipase C (PC-PLC) or by a more complex pathway, involving activation of phospholipase D followed by choline kinase and phosphatidic acid-hydrolase. We show evidence indicating that the generation of phosphorylcholine and diacylglycerol follow independent mechanisms in both serum-treated and in ras-transformed NIH3T3 cells. No significant activation of a PC-PLC enzyme was observed. Instead, activation of a phosphatidylcholine-specific phospholipase D (PC-PLD) was detected. Moreover, while a fivefold constitutive activation of the endogenous PLD activity and a twofold increase on the levels of phosphatidic acid were observed in ras-transformed cells, very small alterations on these parameters were detected at late times after serum stimulation of quiescent cells. Thus, cell proliferation induced by ras oncogenes in fibroblasts cells may be functionally linked to activation of a PC-PLD enzyme. The differences found in the activation of this enzyme between ras-transformed and normal cells may constitute an important difference in mitogenic signalling between normal and transformed cells.

3T3 Cells↗