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Biomedical subjects

J Ramos

Publications and source records attributed to J Ramos.

At least 19 recordsLinked to original sources
PubMed2001

A screening for high copy suppressors of the sit4 hal3 synthetically lethal phenotype reveals a role for the yeast Nha1 antiporter in cell cycle regulation.

A screening for multicopy suppressors of the G(1)/S blockage of a conditional sit4 hal3 mutant yielded the NHA1 gene, encoding a Na(+),K(+)/H(+) antiporter, composed of a transmembrane domain and a large carboxyl-terminal tail, which has been related to cation detoxification processes. Expression of either the powerful Saccharomyces cerevisiae Ena1 Na(+)/H(+)-ATPase or the Schizosaccharomyces pombe Sod2 Na(+)/H(+) antiporter, although increasing tolerance to sodium, was unable to mimic the Nha1 function in the cell cycle. Mutation of the conserved Asp residues Asp(266)-Asp(267) selectively abolished Na(+) efflux without modifying K(+) efflux and did not affect the capacity of Nha1 to relieve the G(1) blockage. Mutagenesis analysis revealed that the region near the carboxyl-terminal end of Nha1 comprising residues 800-948 is dispensable for sodium detoxification but necessary for transport of K(+) cations. Therefore, this portion of the protein contains structural elements that selectively modulate Nha1 antiporter functions. This region is also required for Nha1 to function in the cell cycle. However, expression of the closely related Cnh1 antiporter from Candida albicans, which also contains a long carboxyl-terminal extension, although allowing efficient K(+) transport does not relieve cell cycle blockage. This indicates that although the determinants for Nha1-mediated regulation of potassium transport and the cell cycle map very closely in the protein, most probably the function of Nha1 on cell cycle is independent of its ability to extrude potassium cations.

Amino Acid Sequence↗
PubMed2001

Worsening of hepatic dysfunction as a consequence of repeated hydroxyethylstarch infusions.

BACKGROUND/AIMS: Due to its apparent safety and low cost, hydroxyethylstarch (HES) is increasingly used as a volume expander. The aim of this retrospective study was to highlight the risk of hepatic dysfunction after iterative HES infusions. METHODS: Between April 1996 and April 1998, nine patients were referred for worsening of their clinical condition after repeated HES infusions. Six patients had previous chronic liver disease, cirrhosis in four cases. All patients underwent a liver biopsy. RESULTS: All post-HES liver biopsies showed diffuse microvacuolization of Kupffer cells, which was associated with focal hepatocyte vacuolization in seven cases. The vacuoles contained periodic acid Schiff positive material at their margins and were lysosomal by electron microscopy. The clinical symptoms of hepatic disease, although difficult to interpret in cirrhotic patients, worsened after HES infusions. Portal hypertension was noted in three non-cirrhotic patients. Serum alkaline phosphatase and gammaglutamyl transferase activities were increased when compared with previous values. Eight patients died, six of them within 1-4 weeks of hepatic failure or septic shock. In the only living patient, symptoms improved after HES withdrawal. CONCLUSIONS: Repeated administration of HES could favour severe portal hypertension, liver failure and sepsis, particularly in the setting of chronic liver disease. The basis of these adverse effects is the lysosomal storage of HES in Kupffer cells and hepatocytes.

Aged↗
PubMed2001

Biomechanical and biochemical pulping of sugarcane bagasse with Ceriporiopsis subvermispora fungal and xylanase pretreatments.

Sugarcane bagasse was pretreated with both the white-rot fungus, Ceriporiopsis subvermispora, and xylanase enzyme for 2 weeks before soda chemithermomechanical (CTMP) and soda chemical (CP) cooking. For fungi-CTMP (BCTMP) and enzyme-fungi-CTMP (EBCTMP), the bagasse, after bio-pretreatment, was cooked with 5% sodium hydroxide, at 130 degrees C for 20 min. For the chemical pulping (CP), after fungi pretreatment (BCP) or after xylanase and fungal pretreatment (EBCP), the bagasse was cooked with 14.5% sodium hydroxide. With the BCTMP, the Klason lignin was reduced, all of the pulp strength properties were increased, and a 28% savings in refining energy consumption was obtained, but the brightness was reduced 5 points compared to the control. With the EBCTMP, the brightness losses were overcome but with a mild reduction in the pulp strength properties compared to the BCTMP. The energy savings were 5% greater than from BCTMP and 33% over the control. The BCP treatment increases somewhat the pulp strength properties, reduces the energy consumption 23%, and reduces the brightness by 9 points compared to the control; however, the kappa no. was 5.5 points higher than the control. EBCP treatment reduces brightness losses and increases the pulp yield 2% compared to the control, but with some reduction in the strength properties compared to BCP.

Basidiomycota↗
PubMed2001

Functional study of the Saccharomyces cerevisiae Nha1p C-terminus.

Saccharomyces cerevisiae cells possess an alkali metal cation antiporter encoded by the NHA1 gene. Nha1p is unique in the family of yeast Na+/H+ antiporters on account of its broad substrate specificity (Na+, Li+, K+) and its long C-terminus (56% of the whole protein). In order to study the role of the C-terminus in Nha1p function, we constructed a series of 13 truncated NHA1 versions ranging from the complete one (2958 nucleotides, 985 amino acids) down to the shortest version (1416 nucleotides, 472 amino acids), with only 41 amino acid residues after the last putative transmembrane domain. Truncated NHA1 versions were expressed in an S. cerevisiae alkali metal cation-sensitive strain (B31; ena1-4Delta nha1Delta). We found that the entire Nha1p C-terminus domain is not necessary for either the proper localization of the antiporter in the plasma membrane or the transport of all four substrates (we identified rubidium as the fourth Nha1p substrate). Partial truncation of the C-terminus of about 70 terminal amino acids improves the tolerance of cells to Na+, Li+ and Rb+ compared with cells expressing the complete Nha1p. The presence of the neighbouring part of the C-terminus (amino acids 883-928), rich in aspartate and glutamate residues, is necessary for the maintenance of maximum Nha1p activity towards sodium and lithium. In the case of potassium, the participation of the long C-terminus in the regulation of intracellular potassium content is demonstrated. We also present evidence that the Nha1p C-terminus is involved in the cell response to sudden changes in environmental osmolarity.

Amino Acid Sequence↗
PubMed2001

Expression studies of superoxide dismutases in nodules and leaves of transgenic alfalfa reveal abundance of iron-containing isozymes, posttranslational regulation, and compensation of isozyme activities.

The composition of antioxidant enzymes, especially superoxide dismutase (SOD), was studied in one nontransgenic and three transgenic lines of nodulated alfalfa plants. Transgenic lines overproduced MnSOD in the mitochondria of nodules and leaves (line 1-10), MnSOD in the chloroplasts (line 4-6), and FeSOD in the chloroplasts (line 10-7). In nodules of line 10-7, the absence of transgene-encoded FeSOD activity was due to a lack of mRNA, whereas in nodules of line 4-6 the absence of transgene-encoded MnSOD activity was due to enzyme inactivation or degradation. Transgenic alfalfa showed a novel compensatory effect in the activities of MnSOD (mitochondrial) and FeSOD (plastidic) in the leaves, which was not caused by changes in the mRNA levels. These findings imply that SOD activity in plant tissues and organelles is regulated, at least partially, at the posttranslational level. All four lines had low CuZnSOD activities and an abundant FeSOD isozyme, especially in nodules, indicating that FeSOD performs important antioxidant functions other than the scavenging of superoxide radicals generated in photosynthesis. This was confirmed by the detection of FeSOD cDNAs and proteins in nodules of other legumes such as cowpea, pea, and soybean. The cDNA encoding alfalfa nodule FeSOD was characterized and the deduced protein found to contain a plastid transit peptide. A comparison of sequences and other properties reveals that there are two types of FeSODs in nodules.

Amino Acid Sequence↗
PubMed2001

Cloning and expression of two genes coding for sodium pumps in the salt-tolerant yeast Debaryomyces hansenii.

Two genes encoding Na(+)-ATPases from Debaryomyces hansenii were cloned and sequenced. The genes, designated ENA1 from D. hansenii (DhENA1) and DhENA2, exhibited high homology with the corresponding genes from Schwanniomyces occidentalis. DhENA1 was expressed in the presence of high Na(+) concentrations, while the expression of DhENA2 also required high pH. A mutant of Saccharomyces cerevisiae lacking the Na(+) efflux systems and sensitive to Na(+), when transformed with DhENA1 or DhENA2, recovered Na(+) tolerance and also the ability to extrude Na(+).

Adenosine Triphosphatases↗
PubMed2001

Relationships among perceived justice, customers' satisfaction, and behavioral intentions: the moderating role of gender.

This article tested the gender differences in the relationships between perceptions of justice, customers' satisfaction, and behavioral intentions. The sample consisted of 334 subjects (205 men and 129 women) surveyed in 38 hotels located in Spain. A questionnaire was used to measure distributive, procedural, and interactional justice as well as customers' responses of satisfaction and intentions. Analysis showed that the correlation between scores for distributive justice and customers' satisfaction as well as that between distributive justice and intentions were greater for men than for women. In contrast, the sex differences in the links of procedural and interactional justice to satisfaction and intentions were not significant.

Adult↗
PubMed2001

Abnormal EEG patterns in treatment-resistant schizophrenic patients.

This study was conducted in order to compare the EEG patterns of schizophrenics who do not respond to typical neuroleptics with those who do respond under typical neuroleptic medication and a group of controls. Absolute (AP) and relative power (RP), and inter- and intrahemispheric correlations were calculated. Nonresistant schizophrenics showed lower delta RP, higher alpha 1 AP and RP and higher correlation between prefrontal areas than the resistant ones and controls. Resistant schizophrenics showed lower alpha 2 RP, lower beta 1 and beta 2 in temporal but higher beta 2 AP and RP in occipital derivations, and higher intrahemispheric correlation between Fp2 and F4 and lower between F8 and T4 than the nonresistant and controls. The resistants also showed a higher antero-posterior beta 1 and beta 2 index than the controls. We concluded that the EEG pattern showed by the nonresistants may be associated with their good neuroleptic response that was not present in the resistant schizophrenics.

Adult↗
PubMed2001

Glucose-induced activation of rubidium transport and water flux in sunflower root systems.

Excised 20-d-old sunflower roots (Helianthus annuus L. cv. Sun-Gro 393) were used to study the effect of different sugars on rubidium and water fluxes. The roots sensed and absorbed glucose from the external medium inducing the activation of rubidium accumulated in the root (Rb(+) root), the flux of exuded rubidium (J(Rb)) and, to a lesser degree, the exudation rate (J(v)). These effects were also triggered by fructose, but not by 6-deoxyglucose (6-dG), a glucose analogue which is not a substrate for hexokinase (HXK). The effect of 2-deoxyglucose (2-dG), an analogue that is phosphorylated but not further metabolized, was complex, suggesting an inhibitory effect on solute transport to the xylem. The amounts of glucose required to activate rubidium and water fluxes were similar to those previously reported to regulate different processes in other plants (0.5--10 mM). When sorbitol was used instead of glucose, neither rubidium uptake (Rb(+) root plus J(Rb)) nor J(v) was activated. It is proposed that glucose present in the root plays an important signalling role in the regulation of Rb(+) (K(+)) and water transport in plant roots.

Carbon Radioisotopes↗
PubMed2000

Regulation of expression of phospholipase D1 and D2 by PEA-15, a novel protein that interacts with them.

Phospholipase D (PLD), a signal-transducing membrane-associated enzyme, is implicated in diverse processes including apoptosis, ERK activation, and glucose transport. Prior studies have identified specific PLD activators and repressors that directly regulate its enzymatic activity. Using two-hybrid screens, we have identified PEA-15 as a PLD interactor that unexpectedly functions to alter its level of expression. PEA-15 is a widely expressed death effector domain-containing phosphoprotein involved in signal transduction, apoptosis, ERK activation, and glucose transport. The PLD1-interacting site on PEA-15 consists of part of the death effector domain domain plus additional C-terminal flanking sequences, whereas the PEA-15-interacting site on PLD1 overlaps the previously identified RhoA-interacting site. PEA-15 did not affect basal or stimulated in vitro PLD1 enzymatic activation. However, co-expression of PEA-15 increased levels of PLD1 activity. This increased activation correlated with higher PLD1 protein expression levels, as marked by faster accumulation and longer persistence of PLD1 when PEA-15 was present. PEA-15 similarly increased protein expressions level of PLD2 and co-immunoprecipitated with it. These results suggest that PEA-15 may stabilize PLD or act as a PLD chaperone. The common involvement of PEA-15 and PLD in apoptosis, ERK activation, and glucose transport additionally suggests functional significance.

Alleles↗
PubMed2000

Effects of salts on Debaryomyces hansenii and Saccharomyces cerevisiae under stress conditions.

The effect of Na+ and K+ on growth and thermal death of Debaryomyces hansenii and Saccharomyces cerevisiae were compared under stress conditions as those commonly found in food environments. At the supraoptimal temperature of 34 degrees C both cations at concentrations of 0.5 M stimulated growth of D. hansenii, while K+ had no effect and Na+ inhibited growth of S. cerevisiae. At 8 degrees C, close to the minimum temperature for growth in both species, both cations inhibited both yeasts, this effect being more pronounced with Na+ in S. cerevisiae. At extreme pH values (7.8 and 3.5) both cations at concentrations of 0.25 M stimulated D. hansenii while Na+ inhibited S. cerevisiae. K+ inhibited this yeast at pH 3.5. Thermal inactivation rates, measured at 38 degrees C in D. hansenii and at 48 degrees C in S. cerevisiae, decreased in the presence of both cations. This protective effect could be observed in a wider range of concentrations in D. hansenii. These results call the attention to the fact that not all yeasts have the same behaviour on what concerns synergy or antagonism of salt together with other stress factors and should be taken into consideration in the establishment of food preservation procedures.

Potassium↗
PubMed2000

Eleven novel APC mutations identified in Portuguese FAP families.

Germline mutations of the adenomatous polyposis coli (APC) gene are responsible for familial adenomatous polyposis (FAP), an autosomal dominant predisposition to colorectal cancer. In the present study we screened all of the exons of the APC gene in individuals belonging to 85 Portuguese FAP families. We here report eleven novel mutations which are predominantly frameshifts or single base substitutions, resulting in premature stop codons. Hum Mutat 16:178, 2000.

Adenomatous Polyposis Coli↗
PubMed2000

Potassium and sodium fluxes in the phytopathogenic fungus Fusarium oxysporum var. lini.

Rubidium uptake in potassium-starved cells followed biphasic kinetics in the micromolar and millimolar range and was independent of the temperature. In contrast, Rb(+) uptake in normal-K(+) cells followed a monophasic kinetics in the millimolar range and increased at temperatures higher than 30 degrees C. Differences in the K(m) values and in the Arrhenius plots of Rb(+) uptake suggest different uptake systems in K(+)-starved and in normal-K(+) cells. In addition, the substantial inhibition of Rb(+) uptake caused by carbonyl cyanide-m-chlorophenyl hydrazone indicates that these systems are strongly dependent on membrane voltage. Lithium (sodium) tolerance, influx, and efflux were separately studied. F. oxysporum was shown to be very tolerant to sodium, while lithium caused a specific toxic effect. Li(+) uptake in K(+)-starved cells exhibits a monophasic kinetics with low affinity. Li(+) efflux was not affected by external pH or addition of potassium to the medium, suggesting that a Na(+)/cation antiporter is not involved in this process.

Carbonyl Cyanide m-Chlorophenyl Hydrazone↗
PubMed2000

Hartshill rectangle: failure of spinal stabilisation in acute spinal cord injury.

A high rate of failure of the internal fixation of unstable spinal fractures in complete cord injured patients was noted in patients referred to the Salisbury Spinal Centre who had been stabilised with a Hartshill rectangle. This prompted a review of the operative notes, radiographs and clinical outcomes of all patients referred to the centre with a Hartshill rectangle in situ. All patients identified with a complete spinal cord injury and Hartshill rectangle were identified. Forty-three such patients referred from 13 different centres were found. Pre- and postoperative radiographs were assessed for fracture pattern and for spinal correction. Operative outcome in terms of pain and complications relating to surgery were identified. The most recent radiographs were assessed for signs of loss of reduction or stabilisation. Follow-up averaged 84 months (range 36-132 months). Of the 43 identified patients, 19 were found to have unsatisfactory stabilisation. Persistent pain, broken implants and worsening kyphosis were the main complications. The failure to use bone graft at the time of stabilisation was significantly (P < 0.001) related to risk of failure. The application and use of the Hartshill is not a technically challenging procedure; however, if the system is to be used, it must be used correctly. Failure to correctly apply the rectangle and to use bone graft will lead to an unacceptably high rate of failure.

Adolescent↗
PubMed2000

LC analysis of benzophenone-3: II application to determination of 'in vitro' and 'in vivo' skin penetration from solvents, coarse and submicron emulsions.

The aim of this study was to determine the skin penetration of benzophenone-3 in vitro and in vivo in order to investigate a possible influence of formulation. Six different vehicles, three solvents and three different emulsion types were evaluated in vitro and in vivo. Each vehicle was applied to the skin model at 2 mg cm(-2). First, histological studies on ear pigskin and human skin were evaluated. In vitro measurements were performed with static diffusion cells using pigskin at 1, 2, 4, and 8-h. In vivo, benzophenone-3 concentration in stratum corneum was evaluated by the stripping method after 30-min application on forearm of volunteers. It was shown that ear pigskin and human skin appear similar and in both experiments significant differences between vehicles were noticed. The six vehicles could be ranked in the same order of benzophenone-3 skin concentration. At 8-h, the highest concentration of benzophenone-3 in skin was obtained with propylene glycol, and O/W submicron emulsion. On the contrary. the two oily solvents. W/O emulsion and O/W coarse emulsion restrain the concentration of this UV-filter in the skin. At each time, permeability in vitro and in vivo were well correlated. Low concentrations were measured in the receptor fluid suggesting that percutaneous absorption of this UV-filter across the skin would be minimal. The in vitro and in vivo skin penetration capacity of benzophenone-3 from six vehicles was confirmed and quantified. A satisfactory relationship between binary in vitro and in vivo was established.

Adult↗
PubMed2000

Degradation of Aux/IAA proteins is essential for normal auxin signalling.

The growth substance auxin mediates many cellular processes, including division, elongation and differentiation. PSIAA6 is a member of the Aux/IAA family of short-lived putative transcriptional regulators that share four conserved domains and whose mRNAs are rapidly induced in the presence of auxin. Here PSIAA6 was shown to serve as a dominant transferable degradation signal when present as a translational fusion with firefly luciferase (LUC), with an in vivo half-life of 13.5 min in transgenic Arabidopsis seedlings. In a transient assay system in tobacco protoplasts using steady-state differences as an indirect measure of protein half-life, LUC fusions with full-length PSIAA6 and IAA1, an Aux/IAA protein from Arabidopsis, resulted in protein accumulations that were 3.5 and 1. 0%, respectively, of that with LUC alone. An N-terminal region spanning conserved domain II of PSIAA6 containing amino acids 18-73 was shown to contain the necessary cis-acting element to confer low protein accumulation onto LUC, while a fusion protein with PSIAA6 amino acids 71-179 had only a slight effect. Single amino acid substitutions of PSIAA6 in conserved domain II, equivalent to those found in two alleles of axr3, a gene that encodes Aux/IAA protein IAA17, resulted in a greater than 50-fold increase in protein accumulation. Thus, the same mutations resulting in an altered auxin response phenotype increase Aux/IAA protein accumulation, providing a direct link between these two processes. In support of this model, transgenic plants engineered to over-express IAA17 have an axr3-like phenotype. Together, these data suggest that rapid degradation of Aux/IAA proteins is necessary for a normal auxin response.

Arabidopsis↗
PubMed2000

Sensitization to individual allergens as risk factors for lower FEV1 in young adults. European Community Respiratory Health Survey.

BACKGROUND: Atopy may impair ventilatory function, but results are controversial. We assess the association between individual reactivity to allergens and the level of baseline maximal one-second forced expiratory volume (FEV1), by smoking and respiratory symptoms. METHODS: The 1472 participants (response 44.5%) of the five Spanish areas of the European Community Respiratory Health Survey (ECRHS) who performed respiratory function tests, skin prick tests and/or specific IgE against common aeroallergens (e.g. mites, pets, mould, pollens) are included. Bronchial hyperreactivity (BHR) was measured with a methacholine challenge. RESULTS: After adjusting for BHR and smoking, in addition to the other allergens, skin reactivity to Alternaria (-208 ml; 95% CI :-451, 35) and IgE antibodies against cat (-124 ml; 95% CI:-269, 21) and Timothy grass (-115 ml, 95% CI:-190, -40) were associated with a decrease in FEV1 in females. Among males, skin reactivity to olive showed the strongest association (-111 ml; 95% CI: -261, 38). The associations were stronger in females. Smoking modifies the association for Alternaria and cat (P for interaction < 0.05). While cat is associated with a decrease in FEV1 in current smokers (-190 ml), Alternaria (-336 ml) was associated among never smokers. The exclusion of subjects with asthma symptoms, or adjustment for respiratory symptoms, led to similar results. CONCLUSIONS: We conclude that immunoresponse to individual allergens (particularly outdoor) is associated with the level of FEV1, and this association occurred independently of asthma, and in smokers and non-smokers, which may be of interest in natural history of chronic obstructive pulmonary disease (COPD).

Adult↗