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R Serrano

Publications and source records attributed to R Serrano.

At least 19 recordsLinked to original sources
PubMed1995

A salt-sensitive 3'(2'),5'-bisphosphate nucleotidase involved in sulfate activation.

Overexpression of a yeast gene, HAL2, allows the cells to tolerate higher than normal extracellular salt concentrations. HAL2 encodes a 3'(2')5'-bisphosphate nucleotidase that serves to remove the end products of sulfate transfer during cellular metabolism. The enzyme is inhibited by lithium and sodium and is activated by potassium. Metabolic systems that are sensitive to salt, as well as those governing osmolyte synthesis and ion transport, offer routes by which genetic engineering can be used to improve the tolerance of various organisms to salt.

Adenosine Diphosphate↗
PubMed1995

Regulation of cation transport in Saccharomyces cerevisiae by the salt tolerance gene HAL3.

Dynamic regulation of ion transport is essential for homeostasis as cells confront changes in their environment. The gene HAL3 encodes a novel component of this regulatory circuit in the yeast Saccharomyces cerevisiae. Overexpression of HAL3 improves growth of wild-type cells exposed to toxic concentrations of sodium and lithium and suppresses the salt sensitivity conferred by mutation of the calcium-dependent protein phosphatase calcineurin. Null mutants of HAL3 display salt sensitivity. The sequence of HAL3 gives little clue to its function. However, alterations in intracellular cation concentrations associated with changes in HAL3 expression suggest that HAL3 activity may directly increase cytoplasmic K+ and decrease Na+ and Li+. Cation efflux in S. cerevisiae is mediated by the P-type ATPase encoded by the ENA1/PMR24 gene, a putative plasma membrane Na+ pump whose expression is salt induced. Acting in concert with calcineurin, HAL3 is necessary for full activation of ENA1 expression. This functional complementarity is also reflected in the participation of both proteins in recovery from alpha-factor-induced growth arrest. Recently, HAL3 was isolated as a gene (named SIS2) which when overexpressed partially relieves loss of transcription of G1 cyclins in mutants lacking the protein phosphatase Sit4p. Therefore, HAL3 influences cell cycle control and ion homeostasis, acting in parallel to the protein phosphatases Sit4p and calcineurin.

Adenosine Triphosphatases↗
PubMed1994

Activation of plant plasma membrane H(+)-ATPase by the non-ionic detergent Brij 58.

Plasma membrane vesicles were purified from tobacco callii and the modulation of H(+)-ATPase by detergents was investigated. The nonionic detergent Brij 58 not only activated ATP hydrolysis (2-fold) but also proton pumping (more than 4-fold). Triton X-100, within a more limited concentration range, produced a similar effect. The simultaneous activation of ATP hydrolysis and proton pumping is not compatible with current interpretations of effects of nonionic detergents on the H(+)-ATPase based on latency of the enzyme and opening of vesicles.

Cell Membrane↗
PubMed1994

[A randomized prospective study of antibiotic prophylaxis compared to lavage of the surgical wound in nonperforating appendicitis].

BACKGROUND: There are many doubts as to the efficacy of systemic antibiotic prophylaxis versus the methods of local treatment in the prevention of infection of the contaminated surgical wound. A controlled prospective study was designed to compare the effectiveness of a combination of parenteral antibiotics with lavage with physiologic serum of the surgical wound to prevent infection of the postappendectomy wound. METHODS: The patients in group A (antibiotic, n = 70) received a sole preoperative dose of methronidazol and gentamicin while in those in group I (irrigation, n = 71) the wounds were irrigated with physiologic serum prior to and following closure of aponeurosis. The patients were controlled at one week and one month after the intervention. RESULTS: The global rate of infection was 9.3%. Six patients of group A and five of group I developed wound infection (p = 0.06), The age and length of the intervention were significantly higher in the infected patients (41 vs 23 years, p = 0.0001 and 53 vs 41 minutes, p = 0.03, respectively). Intraperitoneal culture was positive in 70% of the patients who posteriorly developed wound infection, being positive in only 9.4% of the uninfected patients (p = 0.0001). Eight of the infections (73%) were detected following discharge from hospital. The cost of prophylaxis in group A was seven-fold higher than that of group I. CONCLUSIONS: Lavage of the surgical wound with physiologic serum may be an effective, safe and inexpensive method to prevent infection of the wound following appendicectomy for unperforated appendicitis.

Acute Disease↗
PubMed1994

[138 episodes of bacteremia or fungemia in patients with solid organ (renal or hepatic) transplantation].

BACKGROUND: To study the bacteremias and fungemias of the patients with solid organ transplantation (kidney or liver) and analyze the differences according to the type of graft. METHODS: A prospective study included in a control program of bacteremias of a 1000-bed hospital and a follow up study of the infections of the patients who had undergone kidney transplantation (KT) (1985-1991) and liver transplantation (LT) (1988-1991) were carried out. RESULTS: One hundred thirty-one bacteremias and 5 fungemias, 75 in 62 patients with KT out of a total of 568 transplantations (11%) and 63 out of 54 patients with LT out of a total of 185 transplantations (29%) were identified. The prevalence of bacteremia in LT was greater (p < 0.001). The origin was nosocomial in 95% in LT and 70% in KT (p < 0.001). Around 50% of the bacteremias occurred during the first month post LT and KT. The microorganisms isolated were: Staphylococcus sp. (21 in KT and 30 in LT), with greater incidence in LT (p < 0.05); Enterococcus sp. (9 and 5, respectively), enterobacterias (12 and 12, respectively), Pseudomonas sp. (14 and 6, respectively), Candida sp. (2 and 3, respectively) with similar rates in both transplants. The origin of bacteremia was; renal and urinary tract, most frequent in KT (21 and 2 respectively) (p = 0.001). The origin of bacteremia was: renal and urinary tract, most frequent in KT (21 and 2 respectively) (p < 0.001), intraabdominal and biliary tract, most frequent in LT (4 and 14, respectively) (p = 0.007); intravenous catheter, most frequent in LT (16 and 24 respectively) (p < 0.05); lung, most frequent in LT although without statistical significance (3 and 8, respectively), (p = NS), and finally, surgical wound (4 and 1, respectively) (p = NS). Seventeen patients died (14 with LT and 3 with KT). CONCLUSIONS: The incidence of bacteremia and the mortality related, was greater in LT than that observed in KT. The most frequent origin in KT was the kidney and urinary tract and the biliary and intraabdominal organs and the intravenous catheter were most prevalent in liver transplants. Staphylococcus sp was the most frequent germ in both types of transplantation and polymicrobian infection in liver transplants. Gram-negative germs caused higher mortality in liver transplantation.

Bacteremia↗
PubMed1994

Changes in brain enkephalin immunostaining after acute carbon disulfide exposure in rats.

Carbon disulfide neurotoxic mechanism in the brain is still not completely clear. In this work, the effect of carbon disulfide exposure in rats on the enkephalinergic neuromodulatory system is described. Caudatus-putamen showed no changes in immunostaining for met-enkephalin when compared with controls. However, a marked reduction in met-enkephalin immunostaining in the central amygdaloid nuclei and the globus pallidus was measured, with a parallel elevation in the lateral septal nucleus and the parietal cortex. It is suggested that enkephalinergic neuromodulatory system could play a role in carbon disulfide neurotoxicity.

Animals↗
PubMed1993

[Mitral endocarditis caused by Staphylococcus aureus resistant to methicillin, aminoglucosides and rifampicin: description of 2 cases with fatal course].

Two patients with infectious endocarditis (IE) by Staphylococcus aureus resistant to methicillin, aminoglucosides and rifampicin (SARMAR) acquired in hospital during the course of an epidemic outbreak of this microorganism in the Hospital Clínic i Provincial of Barcelona. Both patients had undergone surgery of the lower limbs. The entrance of the microorganism was the infection of the surgical wound, with bacteriemia, followed by mitral IE after a short time interval (20 days). Despite adequate treatment with vancomycin both patients died. The culture of mitral vegetation was positive for SARMAR in one. Analysis of the chromosomic DNA of all the isolations from the patients was identical and coincided with that of the SARMAR strains isolated in the epidemic outbreak of the hospital. The current situation of IE by SARMAR is reviewed and the therapeutic implications commented upon suggesting that treatment of this entity should simultaneously include the administration of vancomycin and phosphomycin or cotrimoxazole, with surgery being considered if infection persists.

Aged↗
PubMed1993

Structure, function and regulation of plasma membrane H(+)-ATPase.

Most antigenic determinants of yeast ATPase are located within its N-terminal part. Amino acids 24-56, required for insertion at the plasma membrane, are highly accessible. The C-terminus behaves as a modulable auto-inhibitory domain in both yeast and plant ATPases. The expression of functional plant enzyme in yeast allows its mutational analysis. Plant tissues involved in active transport, such as the stomata guard cells, phloem, root epidermis and endodermis, are enriched in ATPase. One isoform is phloem-specific. The fact that auxin induces the synthesis of ATPase in corn coleoptiles provides molecular support to the 'Acid growth' theory.

Amino Acid Sequence↗
PubMed1993

Epitope mapping and accessibility of immunodominant regions of yeast plasma membrane H(+)-ATPase.

Immunodominant regions of yeast plasma membrane H(+)-ATPase have been mapped by two different approaches. A rabbit polyclonal antibody was used to screen a library of random fragments of the ATPase gene in a bacterial expression plasmid. In addition, the epitopes recognized by a panel of mouse monoclonal antibodies against the ATPase were mapped by reactions with defined fragments of the enzyme expressed in Escherichia coli. Both methodologies indicated that two regions within the amino-terminal part of the ATPase (at amino acid positions 5-105 and 168-255) contain most of the antigenic determinants. The accessibility of the monoclonal antibodies to their epitopes in native and solvent-perturbed ATPase preparations was investigated by immunofluorescence studies on yeast protoplasts. Cells fixed and permeabilized with formaldehyde were either treated with or without detergents and organic solvents. ELISA competition tests with plasma membrane vesicles and with detergent-purified ATPase incubated in solution with the monoclonal antibodies gave similar results. All the epitopes were accessible in detergent-treated ATPase preparations. In contrast, only the epitopes at amino acids 24-56 were accessible in ATPase preparations not treated with detergents or organic solvents. These epitopes were cytoplasmic because protoplast permeabilization was required for decoration by the reactive monoclonal antibodies.

Amino Acid Sequence↗
PubMed1993

Salt tolerance and methionine biosynthesis in Saccharomyces cerevisiae involve a putative phosphatase gene.

The progressive salinization of irrigated land poses a threat to the future of agriculture in arid regions. The identification of crucial metabolic steps in salt tolerance is important for the understanding of stress physiology and may provide the tools for its genetic engineering. In the yeast Saccharomyces cerevisiae we have isolated a gene, HAL2, which upon increase in gene dosage improves growth under NaCl and LiCl stresses. The HAL2 protein is homologous to inositol phosphatases, enzymes known to be inhibited by lithium salts. Complementation analysis demonstrated that HAL2 is identical to MET22, a gene involved in methionine biosynthesis. Accordingly, methionine supplementation improves the tolerance of yeast to NaCl and LiCl. These results demonstrate an unsuspected interplay between methionine biosynthesis and salt tolerance.

Adaptation, Physiological↗
PubMed1992

Functional expression of plant plasma membrane H(+)-ATPase in yeast endoplasmic reticulum.

Recombinant plant plasma membrane H(+)-ATPase has been produced in a yeast expression system comprising a multicopy plasmid and the strong promoter of the yeast PMA1 gene. Western blotting with a specific monoclonal antibody showed that the plant ATPase is one of the major membrane proteins made by the transformed cells, accounting for about 1% of total yeast protein. The plant ATPase synthesized in yeast is fully active. It hydrolyzes ATP, pumps protons, and the reaction cycle involves a phosphorylated intermediate. Phosphorylation is possible from both ATP and Pi. Unlike the situation in plants, however, most of the plant ATPase is not expressed in the yeast plasma membrane. Rather, the enzyme appears to remain trapped at a very early stage of secretory pathway: insertion into the endoplasmic reticulum. This organelle was observed to proliferate in the form of stacked membranes surrounding the yeast nucleus in order to accommodate the large amount of plant ATPase produced. In this location, the plant ATPase can be purified with high yield (70 mg from 1 kg of yeast) from membranes devoid of endogenous yeast plasma membrane H(+)-ATPase. This convenient expression system could be useful for other eukaryotic membrane proteins and ATPases.

Adenosine Triphosphate↗
PubMed1992

A novel and conserved salt-induced protein is an important determinant of salt tolerance in yeast.

We have isolated a novel yeast gene, HAL1, which upon overexpression improves growth under salt stress. In addition, disruption of this gene decreases salt tolerance. Therefore HAL1 constitutes a rate-limiting determinant for halotolerance. It encodes a polar protein of 32 kDa located in the yeast cytoplasm and unrelated to sequences in data banks. The expression of this gene is increased by high concentrations of either NaCl, KCl or sorbitol. On the other hand, the growth advantage obtained by overexpression of HAL1 is specific for NaCl stress. In cells overexpressing HAL1, sodium toxicity seems to be counteracted by an increased accumulation of potassium. The HAL1 protein could interact with the transport systems which determine intracellular K+ homeostasis. The HAL1 gene and encoded protein are conserved in plants, being induced in these organisms by salt stress and abscisic acid. These results suggest that yeast serves as a convenient model system for the molecular biology of plant salt tolerance.

Amino Acid Sequence↗
PubMed1992

High level expression of streptokinase in Escherichia coli.

Streptokinase (SK), which activates human plasminogen by promoting its conversion to plasmin, is normally obtained from beta-hemolytic streptococci. Treatment with SK is an effective therapy for improving survival and preserving left ventricular function after coronary thrombosis. We report the cloning, expression in E. coli to levels of 25% of the total cell protein, and characterization of a novel SK (SKC-2) gene, the product of which is functionally equivalent to the naturally-derived protein. The availability of a recombinant streptokinase (rSK) in high yield and purity offers a potentially attractive alternative source of this important therapeutic agent.

Amino Acid Sequence↗
PubMed1992

The regulatory domain of fungal and plant plasma membrane H(+)-ATPase.

The activity of fungal and plant plasma membrane H(+)-ATPases seems to be regulated by modulation of the interaction of an inhibitory domain at the C-terminus with the active site. In the yeast ATPase, a mutation at the active site (Ala547- > Val) and a deletion of the C-terminus result in constitutive activation. A double Ser911- > Ala, Thr912- > Ala mutation at the C-terminus (defining putative phosphorylation sites) locks the enzyme in the inhibited state and can be suppressed by the Ala547- > Val mutation at the active site. This provides genetic evidence for domain interaction. In plant ATPase, proteolytic removal of the C-terminus also results in constitutive activation. A peptide covering a region of the plant C-terminus with homology to the yeast C-terminus inhibits the truncated plant ATPase. This suggests similar regulatory mechanisms in fungal and plant ATPases.

Cell Membrane↗
PubMed1991

Identification of an autoinhibitory domain in the C-terminal region of the plant plasma membrane H(+)-ATPase.

Proteolytic (trypsin) treatment removes a small terminal segment from the 100-kDa plant plasma membrane H(+)-ATPase. This results in activation of H+ pumping across the plasma membrane, suggesting that an inhibitory domain is located in one of the terminal regions of the enzyme (Palmgren, M.G., Larsson, C., and Sommarin, M. (1990) J. Biol. Chem. 265, 13423-13426). In order to identify the origin of the fragment released by trypsin, polyclonal antibodies were raised against the first 55 amino acids (N-terminal region), the last 99 amino acids (C-terminal region), and a portion of 150 amino acids in the central part of the enzyme as deduced from one of the H(+)-ATPase genes (PMA2) of Arabidopsis thaliana. The native, 100-kDa H(+)-ATPase was recognized by all three antisera in Western blots. By contrast, the approximately 90-kDa polypeptide appearing after trypsin treatment was only recognized by the antisera against the N-terminal and central region, but not by the antiserum against the C-terminal region, suggesting that the inhibitory domain is located in this part of the enzyme. To more closely determine the position of the inhibitory domain, three peptides representing conserved parts of the C-terminal region were synthesized (residues 861-888, 912-943, and 936-949 of the Arabidopsis (PMA2) sequence). Only one of the peptides (residues 861-888) affected H+ pumping by the trypsin-activated (approximately 90-kDa) enzyme. This peptide of 28 amino acids inhibited H+ pumping with an IC50 of about 15 microM, suggesting that the auto-inhibitory domain is located within the corresponding part of the C-terminal region.

Adenosine Triphosphate↗