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Biomedical subjects

F Valverde

Publications and source records attributed to F Valverde.

At least 19 recordsLinked to original sources
PubMed2003

Two new mutations in cis on (G)gamma chain of fetal hemoglobin: Hb F-Madrid [G gamma 50(D1)Ser-->Cys] and [G gamma 75(E19)Ile-->Thr].

We describe a new structural hemoglobin variant of (G)gamma with two amino acid replacements in cis found in the umbilical cord blood of a neonate in Madrid, Spain. The substitutions were identified on exon 2 of the (G)gamma globin gene, at codon 50 (T CT-->T GT) and at codon 75 (A TA-->A CA). We have named it Hb F-Madrid. The father of the propositus was the carrier of the same (G)gamma chain variant and, moreover, molecular study of alpha genes revealed the loss of an alpha gene (-alpha(3.7)/alpha alpha) both in the propositus and his mother.

Base Sequence↗
PubMed2003

Bullous scleroderma-like changes in chronic graft-versus-host disease.

Cutaneous graft-versus-host disease (GVHD) is the most common clinical setting for GVHD after bone marrow transplantation. Chronic cutaneous GVHD is categorized according to the type of skin lesions into lichenoid and sclerodermoid variants, but bullous scleroderma-like changes are exceptional. Recently, we studied a patient with these alterations. This is the second case described in the literature.

Adolescent↗
PubMed2003

Psoriasis, vasculitis and methotrexate.

Report on the association of the psoriasis and vasculitis are a very infrequent in the literature. Such an association as been described in extensive psoriasis and arthropathy psoriasis. In this paper we described two cases in which psoriasis, vasculitis and nephropathy are present together. In both cases the association might be produced by methotrexate. In both cases methotrexate is possible uleashing.

Adult↗
PubMed2003

[The olfactory bulb as a model for experimental studies].

The olfactory bulb represents a model for several research works carried out in our laboratory. Several details concerning structure, cell varieties and connections have been described. Special attention should be given to the ensheathing glia which accompanies olfactory axons, it being responsible for its plasticity and regeneration, as well as intervening in glomerular formation and their specificity. The olfactory system also represents a good model for the study of certain developmental aspects of the nervous system, such as the formation of nerve tracts. The lateral olfactory tract extends into the basal telencephalon and its development is supported by the existence of pre-existing routes and several attractive or repulsive factors. Its development requires complex molecular interactions in combination with several signalling influences. Pax6 is a transcription factor required for brain development. Nasal structures and eyes are absent in the homozygous mutant mice. In this mutant we have described the presence of one particular structure which could be a prospective olfactory bulb. Specific cell markers have been used to demonstrate that this structure shows many structural characteristics of the olfactory bulb. These observations favor the hypothesis of the existence of specific patterns delimiting specific functional domains in absence of their proper afferent fibers.

Humans↗
PubMed2002

Characterization of a new hemoglobin variant: Hb Badalona (beta31[B13]Leu-->Val).

Hemoglobin (Hb) Badalona was identified in a 35-year-old Spanish female and two other family members. All affected subjects presented erythrocytosis and increased oxygen affinity (P(50): 21 mmHg). Hemoglobinopathy was not detected with electrophoretic methods. It was, however, separated and quantified by cation exchange and reverse-phase high-performance liquid chromatography. Hb Badalona accounted for 35% of the total Hb. No significant clinical symptoms were found to be related to this hemoglobinopathy. This is the first case of a Leu-->Val replacement at position beta31(B13) reported in the world literature.

Adolescent↗
PubMed2001

Simultaneous occurrence of two different glyceraldehyde-3-phosphate dehydrogenases in heterocystous N(2)-fixing cyanobacteria.

Enzyme activity determinations and Western and Northern blot analyses have shown the presence of two catalytically different glyceraldehyde-3-phosphate dehydrogenases (GAPDH) in both vegetative cells and heterocysts of several N(2)-fixing Anabaena strains: (a) the gap2-encoded NAD(P)-dependent GAPDH2 (EC 1.2.1.59), the enzyme involved in the photosynthetic carbon assimilation pathway, which is present at higher levels in vegetative cells, and (b) the gap3-encoded NAD-dependent GAPDH3 (EC 1.2.1.12), presumably involved in carbohydrate anabolism and catabolism, which is the predominant GAPDH in heterocysts. In contrast, the gap1-encoded GAPDH1, which is the other NAD-dependent cyanobacterial GAPDH, is virtually absent in both cell types. These findings are discussed in the context of carbon metabolism of heterocystous N(2)-fixing cyanobacteria.

Anabaena↗
PubMed2001

CONSTANS mediates between the circadian clock and the control of flowering in Arabidopsis.

Flowering is often triggered by exposing plants to appropriate day lengths. This response requires an endogenous timer called the circadian clock to measure the duration of the day or night. This timer also controls daily rhythms in gene expression and behavioural patterns such as leaf movements. Several Arabidopsis mutations affect both circadian processes and flowering time; but how the effect of these mutations on the circadian clock is related to their influence on flowering remains unknown. Here we show that expression of CONSTANS (CO), a gene that accelerates flowering in response to long days, is modulated by the circadian clock and day length. Expression of a CO target gene, called FLOWERING LOCUS T (FT), is restricted to a similar time of day as expression of CO. Three mutations that affect circadian rhythms and flowering time alter CO and FT expression in ways that are consistent with their effects on flowering. In addition, the late flowering phenotype of such mutants is corrected by overexpressing CO. Thus, CO acts between the circadian clock and the control of flowering, suggesting mechanisms by which day length regulates flowering time.

Arabidopsis↗
PubMed2000

Evidence for intrinsic development of olfactory structures in Pax-6 mutant mice.

It has been reported that the arrival of primary olfactory axons is required to induce the development of the olfactory bulb (OB). On the other hand, the Sey(Neu)/Sey(Neu) mutant mouse (Small eye) has been previously described as a model for the absence of olfactory bulbs, owing to the lack of olfactory epithelium (OE). In the present report, we take advantage of this mutant and study a neural structure in the rostral pole of the telencephalon that phenotypically resembles the prospective OB. We named this formation olfactory bulb-like structure (OBLS). We also report the occurrence, in the mutants, of small epithelial vesicles in the malformed craneofacial pits, resembling an atrophic OE, although a mature olfactory nerve was not identified. Axonal tracing, birthdating, immunohistochemistry, and in situ hybridization using antibodies and probes expressed in the olfactory system, indicated that two distinct structures observed in the OBLS correspond to the main and accessory olfactory bulbs of the control mouse. We propose that the OBLS has developed independently of the external influences exerted by the olfactory nerve. The presence of a prospective OB in the mutants, without intervening olfactory fibers, suggests that intrinsic factors could define brain territories even in absence of the proper afferent innervation. The intrinsic mechanisms and environmental cues in the telencephalon could be sufficient to promote axonogenesis in the projection neurons of the OB and guide their axons in a lateral prospective tract, in the absence of olfactory axons.

Animals↗
PubMed2000

Development of the mammillothalamic tract in normal and Pax-6 mutant mice.

The mammillary bodies represent important relay stations for one of the major neuronal circuits in the brain: the limbic circuit. Mammillary projections traveling through the principal mammillary tract are established early during development, forming the mammillotegmental bundle, which appears fully developed by embryonic day 15 (E15). The mammillothalamic tract develops later, around E17-E18, forming a compact system of collateral fibers originating from the principal mammillary tract and reaching the thalamus by E20. The Pax-6 gene is expressed in various regions of the developing brain, among which the border separating the ventral thalamus from the dorsal thalamus, known as the zona limitans intrathalamica, is especially significant. In this report, the development of the efferent mammillary system of fibers was studied in wild type and Pax-6 mutant mice by using carbocyanine tracers and Golgi preparations. In mutant mice, the mammillotegmental bundle developed normally; however, the mammillothalamic tract was missing. By using anti-Pax-6 antibodies in wild type mice, the existence of an immunoreactive cell cluster is described surrounding the bifurcation point of the principal mammillary tract. The results of this study suggest that there is a correlation of these cells with a particular type of Golgi impregnated neuron.

Animals↗
PubMed1999

Engineering a central metabolic pathway: glycolysis with no net phosphorylation in an Escherichia coli gap mutant complemented with a plant GapN gene.

A cDNA fragment containing the Pisum sativum GapN gene, which encodes the non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase, was cloned in a prokaryote expression vector. This construct enabled Escherichia coli strain W3CG, a mutant which lacks the glycolytic phosphorylating G3P dehydrogenase, to grow aerobically on sugars. The functionally complemented mutant exhibited high levels of the catalytically active plant enzyme, which renders 3-phosphoglycerate and NADPH, thus bypassing the first substrate level phosphorylation step of the glycolysis. As expected if such a glycolytic bypass would be operative in vivo, this clone failed to grow anaerobically on sugars in contrast to W3CG clones complemented with phosphorylating glyceraldehyde-3-phosphate dehydrogenases. According to the irreversible catabolic character of the non-phosphorylating reaction, the GapN-complemented clone was unable to grow on gluconeogenic substrates. This metabolic engineering approach demonstrates that a pure catabolic Embden-Meyerhof pathway with no net energy yield is feasible.

Escherichia coli↗
PubMed1998

Central olfactory structures in Pax-6 mutant mice.

During the development of the olfactory system, cells located in the olfactory placode/olfactory pit send their axons toward the rostral part of the telencephalic vesicles (TVs). Some of these enter the TV inducing the formation of the olfactory bulbs (OBs), whereas, mitral and tufted cell axons form the lateral olfactory tract (LOT). Our recent studies have shown that the beginning of the central olfactory projections is independent of the arrival of olfactory receptor neuron (ORN) axons to the TV. Here we have used the mouse carrying a mutation in the Pax-6 gene to study whether the nasal olfactory structures intervene in the formation of central olfactory structures. This mutant as well as lacking a nose and eyes, is reported to lack olfactory epithelium and OB. However, we have found an ovoid cellular structure localized in the rostral part of the brain, and some cells in this structure project axons toward the piriform cortex forming a presumptive LOT. We conclude that the referred structure is an OB, which fails to develop because the mutation in the Pax-6 gene affects the formation of nasal structures. As such, fibers of the ORNs are necessary for the protrusion and layered formation of the OB, but these inputs are not necessary for the establishment of the central olfactory projections.

Animals↗
PubMed1998

Two novel monoclonal antibodies (1.9.E and 4.11.C) against olfactory bulb ensheathing glia.

We produced and characterized two monoclonal antibodies, termed 1.9.E and 4.11.C, that specifically recognize olfactory bulb ensheathing glia. Both antibodies were generated using the olfactory nerve layer (ONL) of newborn rat olfactory bulbs (P0, P1) as immunogens. The specificity of these antibodies was tested by immunofluorescence techniques on tissue sections and cultures of adult and neonatal rat olfactory bulbs, and by Western blot analysis. 1.9.E labeled the ONL and glomerular layer of the olfactory bulb (OB) of adult rats. In newborn rats, 1.9.E immunostained ensheathing cells from the ONL and peripheral olfactory fascicles. Furthermore, 1.9.E reacted with some processes of the radial glia in the periventricular germinal layer of the newborn rat. Although 4.11.C also specifically labeled ensheathing cells in the adult OB, it did not stain any cell type in the ONL of newborn rats. The lack of double labeling with either 1.9.E or 4.11.C and anti-olfactory marker protein (OMP) antibody, a specific marker for olfactory axons, indicated that none of the monoclonals recognized olfactory axons. Double immunostaining of adult OB cultures with 1.9.E or 4.11.C and anti-p75-nerve growth factor receptor revealed that both antibodies specifically recognized ensheathing glia in those cultures. Filaments were strongly labeled throughout the entire cytoplasm of ensheathing cells, suggesting that 1.9.E and 4.11.C immunoreacted with ensheathing glia cytoskeleton. 4.11.C stained a few Schwann cells in adult sciatic nerve sections. Moreover, 4.11.C immunostained cortical astrocyte cultures from newborn rats (P1). In Western blot analysis both antibodies recognized a major component, migrating with an apparent molecular weight of 60 kDa, from olfactory nerve and glomerular layer (ONGL) extracts of adult and neonatal rats. The pattern of immunoreactivity of 1.9.E and 4.11.C antibodies suggest that both antibodies are specific markers for olfactory ensheathing glia in the adult rat central nervous system (CNS).

Animals↗
PubMed1998

Glyceraldehyde-3-phosphate dehydrogenase from Tetrahymena pyriformis: enzyme purification and characterization of a gapC gene with primitive eukaryotic features.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC.1.2.1.12) was purified to electrophoretic homogeneity from an amicronucleated strain of the ciliate Tetrahymena pyriformis using a three-step procedure. The native enzyme is an homotetramer of 145 kDa exhibiting absolute specificity for NAD. In its catalytic properties it is similar to other glycolytic GAPDHs. Chromatofocusing analysis showed the presence of only one basic GAPDH isoform with an isoelectric point of 8.8. Western blots using a monospecific polyclonal antibody raised against the T. pyriformis GAPDH showed a single 36-kDa band corresponding to the enzyme subunit in the cytosolic protein fraction of this strain and the closely related species, both from the class Oligohymenophorea, Paramecium tetraurelia. No bands were immunodetected in the ciliate Colpoda inflata (class Colpodea) and in the diverse eukaryotes and eubacteria tested. A 0.5-kb DNA fragment which corresponds to an internal region of a gapC gene was generated by polymerase chain reaction using cDNA of T. pyriformis as template. This gene codes for a basic GAPDH protein with eukaryotic-diplomonad signatures and exhibits a codon usage biased in the manner typical for T. pyriformis genes. Southern blots performed both under homologous and heterologous conditions using this amplified cDNA fragment as a probe, indicated that it should be the only gapC gene present in the macronuclear genome of this ciliate, its expression being confirmed by Northern blot analysis. These results are discussed in connection with the peculiar genomic organization of ciliates and in the context of protist evolution.

Amino Acid Sequence↗
PubMed1998

[Usefulness of molecular screening in childhood lymphoblastic leukemias].

PURPOSE: To demonstrate that a molecular screening by reverse transcriptase polymerase chain reaction (RT-PCR) of TEL/AML1, E2A/PBX1 and BCR/ABL genes in pediatric acute lymphoblastic leukaemia is a rapid method that allows one to exceed the percentage of adult patients with the BCR/ABL rearrangement. PATIENTS AND METHODS: 12 Spanish children with acute lymphoblastic leukaemia were studied, 11 of them newly diagnosed and 1 relapsed. The patients were between 18 months and 10 years old. Bone marrow aspiration was collected between april and december 1996, RNA was isolated and cDNA was subjected to PCR amplification for TEL/AML1, E2A/PBX1 and BCR/ABL genes. Normal ABL and E2A genes were studied as amplification controls. RESULTS: One of these hybrid genes was found in 33.3% of patients studied. TEL/AML1 in two cases (16.6%), E2A/PBX1 in one case (8.3%) and BCR/ABL in another one (8.3%). CONCLUSIONS: On the basis of these data it would be useful to achieve a molecular screening of TEL/AML1, E2A/PBX1 and BCR/ABL genes in pediatric acute lymphoblastic leukaemia for allowing a molecular classification in a great percentage of patients that exceed the BCR/ABL positivity in adults.

Aneuploidy↗
PubMed1997

Functional complementation of an Escherichia coli gap mutant supports an amphibolic role for NAD(P)-dependent glyceraldehyde-3-phosphate dehydrogenase of Synechocystis sp. strain PCC 6803.

The gap-2 gene, encoding the NAD(P)-dependent D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH2) of the cyanobacterium Synechocystis sp. strain PCC 6803, was cloned by functional complementation of an Escherichia coli gap mutant with a genomic DNA library; this is the first time that this cloning strategy has been used for a GAPDH involved in photosynthetic carbon assimilation. The Synechocystis DNA region able to complement the E. coli gap mutant was narrowed down to 3 kb and fully sequenced. A single complete open reading frame of 1,011 bp encoding a protein of 337 amino acids was found and identified as the putative gap-2 gene identified in the complete genome sequence of this organism. Determination of the transcriptional start point, identification of putative promoter and terminator sites, and orientation of the truncated flanking genes suggested the gap-2 transcript should be monocystronic, a possibility further confirmed by Northern blot studies. Both natural and recombinant homotetrameric GAPDH2s were purified and found to exhibit virtually identical physicochemical and kinetic properties. The recombinant GAPDH2 showed the dual pyridine nucleotide specificity characteristic of the native cyanobacterial enzyme, and similar ratios of NAD- to NADP-dependent activities were found in cell extracts from Synechocystis as well as in those from the complemented E. coli clones. The deduced amino acid sequence of Synechocystis GAPDH2 presented a high degree of identity with sequences of the chloroplastic NADP-dependent enzymes. In agreement with this result, immunoblot analysis using monospecific antibodies raised against GAPDH2 showed the presence of the 38-kDa GAPDH subunit not only in crude extracts from the gap-2-expressing E. coli clones and all cyanobacteria that were tested but also in those from eukaryotic microalgae and plants. Western and Northern blot experiments showed that gap-2 is conspicuously expressed, although at different levels, in Synechocystis cells grown in different metabolic regimens, even under chemoheterotrophic conditions. A possible amphibolic role of the cyanobacterial GAPDH2, namely, anabolic for photosynthetic carbon assimilation and catabolic for carbohydrate degradative pathways, is discussed.

Amino Acid Sequence↗