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J Arroyo

Publications and source records attributed to J Arroyo.

At least 73 records · Page 4Linked to original sources
PubMed1993

Molecular karyotype variation in Leishmania (Viannia) peruviana: indication of geographical populations in Peru distributed along a north-south cline.

Forty-one Leishmania peruviana isolates were selected along a north-south transect which crossed areas endemic for uta in three different biogeographical regions in the Peruvian Andes. The isolates were analysed by molecular karyotyping and hybridization with three chromosome-derived DNA probes. All the isolates could be distinguished from L. braziliensis by their pLb-134 hybridization patterns. However, the patterns with the other probes (pLb-168 and -22) could be used to cluster the Peruvian isolates in discrete groups (karyodemes) which varied in their level of similarity with L. braziliensis. The geographical distribution of these karyodemes supports the hypothesis that eco-graphical isolation has contributed to the heterogeneity of L. peruviana.

Animals↗
PubMed1993

Karyotype polymorphism and conserved characters in the Leishmania (Viannia) braziliensis complex explored with chromosome-derived probes.

Molecular karyotype of 45 reference populations of Neotropical leishmanias was analyzed with ethidium bromide staining and with 6 chromosome-derived probes selected from a genomic library of Leishmania (Viannia) braziliensis. Size-conserved patterns were identified and found to be specific to subgenus Viannia and to its constitutive species. An important issue for epidemiology and clinical investigations was the discrimination between L. (V.) peruviana and L. (V.) braziliensis, 2 species found very similar by other genetic techniques, but responsible for totally different clinical patterns. The suggested existence of genetically distinct demes, or karyodemes, within the group-species might also show to be of importance, as these populations might differ in virulence, host-specificity and clinical manifestations.

Animals↗
PubMed1992

PhoA gene fusions in Legionella pneumophila generated in vivo using a new transposon, MudphoA.

To enable effective use of phoA gene fusions in Legionella pneumophila, we constructed MudphoA, a derivative of the mini-Mu phage Mu dII4041, which is capable of generating gene fusions to the Escherichia coli alkaline phosphatase gene (EC 3.1.3.1). Although an existing fusion-generating transposon, TnphoA, has been a useful tool for studying secreted proteins in other bacteria, this transposon and other Tn5 derivatives transpose inefficiently in Legionella pneumophila, necessitating the construction of a more effective vector for use in this pathogen. Using MudphoA we generated fusions to an E. coli gene encoding a periplasmic protein and to an L. pneumophila gene encoding an outer membrane protein; both sets of fusions resulted in alkaline phosphatase activity. We have begun to use MudphoA to mutate secreted proteins of L. pneumophila specifically, since this subset of bacterial proteins is most likely to be involved in host-bacterial interactions. This modified transposon may be useful for studies of other bacteria that support transposition of Mu, but not Tn5, derivatives.

Alkaline Phosphatase↗
PubMed1991

Characterization of a Legionella pneumophila gene encoding a lipoprotein antigen.

A prominent 19 kDa surface antigen of Legionella pneumophila, cloned in Escherichia coli, was found to be intimately associated with peptidoglycan. The DNA region encoding this antigen was mapped on an 11.9 kb plasmid by means of deletion analysis and transposon mutagenesis. PhoA+ gene fusions, gene-rated by TnphoA insertions into this region, confirmed the presence of a gene encoding a secreted protein. PhoA+ transposon insertions were also associated with loss of the 19 kDa antigen in immunoassays using a monoclonal antibody (mAb1E9) and the replacement of the 19 kDa antigen with larger fusion proteins in immunoblots using Legionella immune serum. A 1540bp PstI fragment carrying the gene was sequenced, and the open reading frame encoding the antigen was identified. The gene encodes a polypeptide 176 amino acid residues long and 18913Da in size. The presence of a signal sequence of 22 amino acids with a consensus sequence for cleavage by signal peptidase II indicates that the antigen is a lipoprotein, and striking similarity with peptidoglycan-associated lipoproteins (PALs) from E. coli (51% amino acid homology) and Haemophilus influenzae (55% homology) is noted. We conclude that the 19kDa antigen of L. pneumophila is the structural equivalent of the PAL found in other Gram-negative species and suggest that its post-translational acylation may explain its potency as an immunogen.

Amino Acid Sequence↗
PubMed1991

A protein kinase gene complements the lytic phenotype of Saccharomyces cerevisiae lyt2 mutants.

By genetic analysis of a thermosensitive autolytic mutant whose phenotype was complemented by osmotic stabilization with sorbitol, we identified gene LYT2 of Saccharomyces cerevisiae, which is probably involved in cell wall formation. A yeast gene complementing lyt2 strains was cloned and shown to carry an open reading frame coding for a 484-amino-acid protein exhibiting all the characteristic domains of serine/threonine protein kinases and highly homologous to other yeast protein kinases involved in control of the mitotic cycle. Mutants disrupted in the cloned gene also displayed an autolytic phenotype complemented by osmotic stabilization with sorbitol. However, genetic comparison of lyt2 mutants and disruptants of the protein kinase gene revealed that the cloned gene is not the structural gene LYT2 but a suppressor of the lytic phenotype, named gene SLT2, that was mapped to chromosome V. The product of gene SLT2 is the first protein kinase to be described in relation to the yeast cell-wall functions.

Amino Acid Sequence↗
PubMed1991

[Fetal hemoglobin in children with different neoplasms].

The rate of HbF was studied in 123 children with different malignancies in order to assess its changes and relationship with other values of peripheral blood. The cases were distributed into 34 with acute lymphoblastic leukaemia (ALL), 19 with acute myelogenous leukaemia (AML), 23 cases of Hodgkin's disease (HD), 16 of non-Hodgkin lymphoma (NHL) and 31 of different solid tumors (ST). ALL and AML groups had the highest HbF rates (2.88 +/- 1.93% and 2.63 +/- 2.7%, respectively), followed by HD and NHL (1.89 +/- 1.09% and 1.81 +/- 1.68%, respectively), whereas the ST group showed the lowest values (1.32 +/- 1.74%). When comparing these figures with the findings in a group of adult leukaemia and lymphoma (1.6 +/- 0,7% and 1.2 +/- 0.5%, respectively), it was found that HbF was increased in the children to a higher extent. The analysis of the gamma G and gamma A chains of HbF, performed on 14 of the patients, showed in 7 cases a correlation similar to the newborn pattern, while this was similar to the adults in the remainders. These findings suggest that some factors intrinsic to the neoplasm might favour, in a different degree, the re-expression of HbF, which, in turn, would not necessarily mean a reversion to the foctal stages since the correlation of the gamma chains was similar to the adult pattern in 50% of the cases studied.

Adolescent↗
PubMed1990

Interaction of [3H]GBR 12935 and GBR 12909 with the dopamine uptake complex in nucleus accumbens.

Although some behavioral effects of cocaine are hypothesized to be due to blockade of dopamine uptake in nucleus accumbens, it has been reported that in nucleus accumbens there are no specific cocaine binding sites and that cocaine is a weak inhibitor of dopamine uptake. [3H]GBR 12935 and an unlabelled analog, GBR 12909, are ligands that bind with great affinity and specificity to a site on dopamine uptake complex in striatum. We therefore investigated the interaction of these GBR compounds with the dopamine uptake complex in nucleus accumbens. We found specific high affinity [3H]GBR 12935 binding and a significant correlation between displacement of [3H]GBR 12935 binding by a series of compounds in striatum and nucleus accumbens. GBR 12909 inhibited dopamine uptake with equal potency in nucleus accumbens and striatum. Thus, there appear to be some aspects of the dopamine uptake complex in nucleus accumbens and striatum that are similar.

Animals↗
PubMed1988

The effect of hypoglycemic sulfonylureas on human red blood cell transglutaminase activity.

We have examined the effect of glipizide, a hypoglycemic sulfonylurea, upon transglutaminase activity in human red blood cells. In a first series of experiments the in vitro effect of the drug was assessed. The results obtained showed that glipizide inhibits transglutaminase activity in human red blood cells. In a second approach, glipizide was administered orally to six type 2 diabetic patients during 3 months, in order to evaluate the long-term effect upon transglutaminase activity. Again, glipizide induced a significant decrease in the enzyme activity in blood red cells (P less than 0.01). We suggest that treatment of type 2 diabetes mellitus with hypoglycemic sulfonylureas could improve insulin effects by inhibiting cellular transglutaminase activity.

Calcium↗
PubMed1986

Sternocostoclavicular hyperostosis. Radiological and pathological study of a specimen with ununited clavicular fracture.

Anatomico-radiological study of a sternocostoclavicular mass taken post-mortem from a man whose clinical history had shown bilateral sternocostoclavicular hyperostosis (SCCH) with plantar pustulosis for 27 years. The clavicle showed an ununited fracture attributable to a trauma sustained five years earlier. Both clavicular segments showed active remodelling with intraosseous granulation tissue and periosteal metaplastic ossification. The sternocostoclavicular region was fused in a bony block in which there were no signs of remodelling activity. The first rib and the distal extremity of the clavicle were histologically normal. These observations support the conclusions of a previous study of another case of SCCH. The condition might be due to a bone infection caused by an--as yet--unknown germ. Bone remodelling would explain the periosteal hyperostosis and the fragility of the underlying bone. Furthermore, the possibility that the condition might also be a joint disease related to the group of rheumatic diseases called spondyloarthropathies should be considered.

Adult↗
PubMed1985

Constitutional mosaic t(2;7)(q33;p22) and other rearrangements in a girl with Wilms' tumor.

A 2-year-old girl with sporadic unilateral Wilms' tumor (WT) not associated with aniridia was found to have, besides other chromosome abnormalities, a t(2;7)(q33;p22) in 6% of her lymphocytes. A comparison with 7 previous WT cases without aniridia in whom diverse chromosomal aberrations were present, reveals a wide heterogeneity and lead us to tentatively classify such changes as causal, secondary, and casual.

Child, Preschool↗
PubMed1983

No evidence for temperature-dependent changes in the pharmacological specificity of beta 1- and beta 2-adrenoceptors in rabbit lung membranes.

In rabbit lung membranes known to contain both beta 1- and beta 2-adrenoceptors it was studied whether changes in incubation temperature may affect binding characteristics and/or selectivity of beta 1- and beta 2-adrenoceptor drugs. For this purpose inhibition of binding of the highly specific beta-adrenoceptor radioligand (+/-)-125iodocyanopindolol (ICYP) by beta 1-and beta 2-selective as well as non-selective drugs was determined at incubation temperatures of 37 degrees C and 18 degrees C and analyzed by Hofstee-plots. 1. The density of beta-adrenoceptors in rabbit lung membranes was identical independently of the incubation temperature. 2. At both incubation temperatures beta 1- and beta 2-selective drugs showed biphasic displacement curves and non-linear Hofstee-plots, while inhibition of binding by the non-selective drugs resulted in monophasic displacement curves with linear Hofstee-plots. With decreasing temperature affinity of antagonists to beta-adrenoceptors increased only slightly, while affinity of agonists increased markedly. 3. For all beta 1- and beta 2-selective drugs the same ratio beta 1/beta 2-adrenoceptors was calculated from the Hofstee-plots independently of the incubation temperature: It amounted to about 80% beta 1- and 20% beta 2-adrenoceptors in rabbit lung. 4. At an incubation temperature of 37 degrees C the displacement curve of the agonist isoprenaline was biphasic in the absence of GTP with a non-linear Hofstee-plot indicating that at 37 degrees C isoprenaline binds to high and low affinity states of the beta-adrenoceptors in rabbit lung. At 18 degrees C, however, beta-adrenoceptors do not form the high affinity GTP-sensitive complex with agonists, since GTP had no influence on isoprenaline displacement curves. 5. It is concluded that a decrease in the incubation temperature of ICYP binding assay from 37 degrees C to 18 degrees C does neither alter the relative amount of beta 1- and beta 2-adrenoceptors in rabbit lung membranes nor the selectivity of beta 1- and beta 2-selective adrenoceptor drugs.

Adrenergic beta-Antagonists↗
PubMed1983

Acute respiratory failure and tracheal obstruction in patients with intrathoracic goiter.

Four cases of acute life-threatening tracheal obstruction due to intrathoracic goiter are reported. Acute respiratory insufficiency caused by an upper airway obstruction in patients with intrathoracic goiter is exceptional. In 3 of 4 cases reported, the histologic study showed multiple foci of recent hemorrhage, the mechanism probably responsible for these episodes.

Adult↗