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Biomedical subjects

E Moreno

Publications and source records attributed to E Moreno.

At least 91 records · Page 5Linked to original sources
PubMed1999

Controlling the maturation of pathogen-containing vacuoles: a matter of life and death.

Once considered to be contained, infectious diseases of bacterial origin are now making a comeback. A lack of innovative therapies and the appearance of drug-resistant pathogens are becoming increasingly serious problems. A better understanding of pathogen-host interactions at the cellular and molecular levels is necessary to define new targets in our fight against microorganisms. In the past few years, the merging of cell biology and microbiology has started to yield critical and often surprising new information on the interactions that occur between various pathogens and their mammalian host cells. Here we focus on the intracellular routing of vacuoles containing microorganisms, as well as on the bacterial effectors and their host-cell targets that control vacuole maturation. We also describe new approaches for isolating microorganism-containing vacuoles and analysing their molecular composition, which will help researchers to define the molecules and mechanisms governing vacuole biogenesis.

Animals↗
PubMed1999

Prospective comparison of therapeutical attitudes in hypertensive type 2 diabetic patients uncontrolled on monotherapy. A randomized trial: the EDICTA study.

OBJECTIVE: To compare the anti-hypertensive effect of combination therapy versus a single drug regimen schedule (dose-titration or switching to a different drug class) in type 2 diabetic hypertensive patients with inadequate blood pressure (BP) control on monotherapy. DESIGN: Prospective, randomized, open-fashion, parallel study of two therapeutic strategies during an 8-week period. SETTING: Primary care centers in Spain. PARTICIPANTS: A total of 898 men and women with type 2 diabetes mellitus and hypertension, receiving antihypertensive treatment with one single drug and whose BP was > 140 and/or 90 mmHg. INTERVENTION: Patients were randomized to a fixed combination therapy (verapamil 180 mg plus trandolapril 2 mg; Knoll AG, Ludwigshafen, Germany) or continued on a single drug regimen, either increasing the dose of the current drug or switching to a different drug class. MAIN OUTCOME MEASURE: Absolute BP reduction in the two groups of treatment, and the percentage of normalized patients (< 140/90 mmHg) in each group. RESULTS: The diastolic BP (DBP) decrease (5.6 mmHg) was significantly greater in patients treated with combination therapy, compared to patients on monotherapy (2.9 mmHg). The decrease in systolic BP (SBP) was not significantly different (11.1 versus 10.0 mmHg). In addition, a significantly higher number of patients treated with combination therapy (82% versus 74%) reached diastolic BP normalization (< 90 mmHg). CONCLUSIONS: In type 2 hypertensive patients with uncontrolled BP despite anti-hypertensive monotherapy, the change to combination therapy was more effective in attaining DBP control than any monotherapy schedule (either increasing the dose or switching to another different drug class).

Aged↗
PubMed1999

Comparison of agar gel immunodiffusion test, enzyme-linked immunosorbent assay and western blotting for the detection of BLV antibodies.

An indirect enzyme-linked immunosorbent assay (ELISA) for the diagnosis of bovine leukaemia virus (BLV) infection was developed and compared with the agar gel immunodiffusion test (AGIDT). Western blotting (WB) was used as confirmatory test. ELISA and AGIDT had specificities that were comparable with that of WB, however, ELISA showed a higher sensitivity than AGIDT. The ELISA was useful for screening a large number of samples, whereas WB was important for detecting the antibody response against the individual BLV-proteins. Different types of positive serological reactions were discerned in WB, that correlated with reactions of sera in AGIDT and ELISA. The most important antigen in WB and ELISA was the BLV protein p24, whereas the BLV glycoproteins gp51 and gp30 were of special importance in AGIDT. The relevance of repeatedly testing the antibody response in BLV-infected herds for control and eradication programmes using assays with higher sensitivity than AGIDT was demonstrated.

Animals↗
PubMed1999

Performance of competitive and indirect enzyme-linked immunosorbent assays, gel immunoprecipitation with native hapten polysaccharide, and standard serological tests in diagnosis of sheep brucellosis.

Competitive and standard enzyme-linked immunosorbent assays (ELISAs), rose bengal (RB), complement fixation, and agar gel immunoprecipitation with native hapten (AGID-NH) were compared by using sera from Brucella-free, Brucella melitensis-infected, and B. melitensis Rev1-vaccinated sheep. The most sensitive tests were indirect ELISA and RB, and the most specific tests were AGID-NH and competitive ELISA. We show that RB followed by AGID-NH is a simple and effective system for diagnosing sheep brucellosis.

Animals↗
PubMed1999

The outer membrane of Brucella ovis shows increased permeability to hydrophobic probes and is more susceptible to cationic peptides than are the outer membranes of mutant rough Brucella abortus strains.

The permeability of the outer membrane (OM) to hydrophobic probes and its susceptibility to bactericidal cationic peptides were investigated for natural rough Brucella ovis and for mutant rough Brucella abortus strains. The OM of B. ovis displayed an abrupt and faster kinetic profile than rough B. abortus during the uptake of the hydrophobic probe N-phenyl-naphthylamine. B. ovis was more sensitive than rough B. abortus to the action of cationic peptides. Bactenecins 5 and 7 induced morphological alterations on the OMs of both rough Brucella strains. B. ovis lipopolysaccharide (LPS) captured considerably more polymyxin B than LPSs from both rough and smooth B. abortus strains. Polymyxin B, poly-L-lysine, and poly-L-ornithine produced a thick coating on the surfaces of both strains, which was more evident in B. ovis than in rough B. abortus. The distinct functional properties of the OMs of these two rough strains correlate with some structural differences of their OMs and with their different biological behaviors in animals and culture cells.

Animals↗
PubMed1999

Interaction of Brucella abortus lipopolysaccharide with major histocompatibility complex class II molecules in B lymphocytes.

Lipopolysaccharide (LPS), a major amphiphilic molecule located at the outer membrane of gram-negative bacteria, is a potent antigen known to induce specific humoral immune responses in infected mammals. LPS has been described as a polyclonal activator of B lymphocytes, triggering the secretion of antibodies directed against distinct sugar epitopes of the LPS chain. But, how LPS is handled by B cells remains to be fully understood. This task appears to be essential for a better knowledge of the anti-LPS humoral immune response. In this study, we examine the internalization of LPS and its interaction with antigen-presenting major histocompatibility complex (MHC) class II molecules in murine and human B-cell lines. By use of immunofluorescence, we observe that structurally different LPSs from Brucella and Shigella strains accumulate in an intracellular compartment enriched in MHC class II molecules. By use of immunoprecipitation, we illustrate that only Brucella abortus LPS associates with MHC class II molecules in a haplotype-independent manner. Taken together, these results raise the possibility that B. abortus LPS may play a role in T-cell activation.

Animals↗
PubMed1999

Clathrin and two components of the COPII complex, Sec23p and Sec24p, could be involved in endocytosis of the Saccharomyces cerevisiae maltose transporter.

The Saccharomyces cerevisiae maltose transporter is a 12-transmembrane segment protein that under certain physiological conditions is degraded in the vacuole after internalization by endocytosis. Previous studies showed that endocytosis of this protein is dependent on the actin network, is independent of microtubules, and requires the binding of ubiquitin. In this work, we attempted to determine which coat proteins are involved in this endocytosis. Using mutants defective in the heavy chain of clathrin and in several subunits of the COPI and the COPII complexes, we found that clathrin, as well as two cytosolic subunits of COPII, Sec23p and Sec24p, could be involved in internalization of the yeast maltose transporter. The results also indicate that endocytosis of the maltose transporter and of the alpha-factor receptor could have different requirements.

Biological Transport↗
PubMed1999

Comparative study of the clinical efficacy of two different coumarin dosages in the management of arm lymphedema after treatment for breast cancer.

In a randomized, double-blind, parallel group study, we compared the clinical efficacy of coumarin 90 mg/day (Group A) with 135 mg/day (Group B) in 77 women (age 35-65 years) with lymphedema of the upper limb secondary to surgery and irradiation for treatment of breast cancer. During 12 months of coumarin therapy, the arm volume of lymphedema and a clinical score (degree of arm edema, heaviness, hardness, and neuralgia/dysesthesia) were determined. In both groups, the volume of arm lymphedema decreased (14.9% in Group A and 13.2% in Group B) (N.S.), the overall clinical score improved (12.9 +/- 4.3 to 5.7 +/- 3.5 in Group A and from 11.7 +/- 3.7 to 4.7 +/- 3.9 in Group B) (N.S.), and the overall efficacy of coumarin was similarly good or excellent (71.9% in Group A and 68.6% in Group B) (N.S.). Only mild to moderate side effects of drug therapy were recorded. Coumarin prevents a spontaneous trend toward an increase in arm lymphedema after treatment of breast cancer, decreases the severity of local symptoms, and overall improves the quality of life. No difference was found between the apparent benefits of coumarin at 90 mg/day compared with 135 mg/day.

Arm↗
PubMed1999

[Hyperlipidemia in liver transplanted patients].

Hyperlipemia is frequent in liver transplanted patients and has been related with the existence of cholestasis, renal insufficiency, obesity, diabetes, and especially with immunosuppressant treatment. Although there are no studies that show a relationship between post-liver transplant hyperlipemia and the development of cardiovascular disease, there are data that indicate that liver transplanted patients should control their cholesterol levels to reduce the incidence of this disease. When post-transplant hyperlipemia is present, hygienic-dietary measures should be established and treatment should be carried out with the minimum dose of cyclosporine needed to maintain the graft stable. Corticoids should be discontinued as soon as possible. Treatment with some statins (Lovastatin and Pravastatin) has shown to be safe and efficacy in the liver transplanted patients with hypercholesterolemia.

Humans↗
PubMed1998

Catabolite inactivation of the maltose transporter in nitrogen-starved yeast could be due to the stimulation of general protein turnover.

Addition of glucose to Saccharomyces cerevisiae inactivates the maltose transporter. The general consensus is that this inactivation, called catabolite inactivation, is one of the control mechanisms developed by this organism to use glucose preferentially whenever it is available. Using nitrogen-starved cells (resting cells), it has been shown that glucose triggers endocytosis and degradation of the transporter in the vacuole. We now show that maltose itself triggers inactivation and degradation of its own transporter as efficiently as glucose. This fact, and the observation that glucose inactivates a variety of plasma membrane proteins including glucose transporters themselves, suggests that catabolite inactivation of the maltose transporter in nitrogen-starved cells is not a control mechanism specifically directed to ensure a preferential use of glucose. It is proposed that, in this metabolic condition, inactivation of the maltose transporter might be due to the stimulation of the general protein turnover that follows nitrogen starvation.

Biological Transport↗
PubMed1998

Alterations in the GAL4 DNA-binding domain can affect transcriptional activation independent of DNA binding.

The GAL4 protein belongs to a large class of fungal transcriptional activator proteins encoding within their DNA-binding domains (DBD) six cysteines that coordinate two atoms of zinc (the Zn2Cys6 domain). In an effort to characterize the interactions between the Zn2Cys6 class transcriptional activator proteins and their DNA-binding sites, we have replaced in the full-length GAL4 protein small regions of the Zn2Cys6 domain with the analogous regions of another Zn2Cys6 protein called PPR1 an activator of pyrimidine biosynthetic genes. Alterations between the first and third cysteines abolished binding to GAL4 (upstream activation sequence of GAL (UASG)) or PPR1 (upstream acitvation sequence of UAS) DNA-binding sites and severely reduced transcriptional activation in yeast. In contrast, alterations between the third and fourth cysteines had only minor effects on binding to UASG but led to substantial decreases in activation in both yeast and a mammalian cell line. In the crystal structure of the GAL4 DBD-UASG complex (Marmorstein, R., Carey, M., Ptashne, M., and Harrison, S. C. (1992) Nature 356, 408-414), this region is facing away from the DNA, making it likely that there exists within the GAL4 DBD an accessible domain important in activation.

Amino Acid Sequence↗
PubMed1998

Bactericidal activity of Lys49 and Asp49 myotoxic phospholipases A2 from Bothrops asper snake venom--synthetic Lys49 myotoxin II-(115-129)-peptide identifies its bactericidal region.

Mammalian group-II phospholipases A2 (PLA2) of inflammatory fluids display bactericidal properties, which are dependent on their enzymatic activity. This study shows that myotoxins II (Lys49) and III (Asp49), two group-II PLA2 isoforms from the venom of Bothrops asper, are lethal to a broad spectrum of bacteria. Since the catalytically inactive Lys49 myotoxin II isoform has similar bactericidal effects to its catalytically active Asp49 counterpart, a bactericidal mechanism that is independent of an intrinsic PLA2 activity is demonstrated. Moreover, a synthetic 13-residue peptide of myotoxin II, comprising residues 115-129 (common numbering system) near the C-terminal loop, reproduced the bactericidal effect of the intact protein. Following exposure to the peptide or the protein, accelerated uptake of the hydrophobic probe N-phenyl-N-naphthylamine was observed in susceptible but not in resistant bacteria, indicating that the lethal effect was initiated on the bacterial membrane. The outer membrane, isolated lipopolysaccharide (LPS), and lipid A of susceptible bacteria showed higher binding to the myotoxin II-(115-129)-peptide than the corresponding moieties of resistant strains. Bacterial LPS chimeras indicated that LPS is a relevant target for myotoxin II-(115-129)-peptide. When heterologous LPS of the resistant strain was present in the context of susceptible bacteria, the chimera became resistant, and vice versa. Myotoxin II represents a group-II PLA2 with a direct bactericidal effect that is independent of an intrinsic enzymatic activity, but adscribed to the presence of a short cluster of basic/hydrophobic amino acids near its C-terminal loop.

Animals↗
PubMed1998

[Expression of different HIV-1 phenotypic subpopulations through the natural history of the infection].

BACKGROUND: Multiple viral subpopulations coexist in an HIV infected patient with dynamics of selection established between them. In order to get insight on the phenotype of these subpoblations, and its relation with disease progression, we have studied the biological variability of HIV-1 in 113 patients. Variability was related with CD4+ T lymphocyte counts, clinical status, way of viral transmission and antiretroviral treatment. PATIENTS AND METHODS: 113 patients (80 adults and 33 children) were studied for HIV-1 isolation in cocultures of infected and non infected lymphocytes. Viral replication was evaluated as rapid (R)/slow (S) or high (H)/low (L). Syncytia formation was estimated in MT2 cell line (SI/NSI). The tropism toward lymphocytes and monocytes (LM) was studied on H9 and U937 cell lines. RESULTS: Up to 86.7% of viral isolates were R, 56.6% were H and 49.6% were SI. These percentages increased with disease progression. Eight viral strains were R/H/NSI cocultivated in MT2 cells and SI in cocultured lymphocytes (NSI/SI), which may be considered as a new phenotype. All the SI isolates and all the R/H (SI and NSI) isolates were LM. Three categories were established: R/H/SI/LM, R/H/NSI/LM and S/L/NSI/NLM. The first two categories corresponded to patients with CD4+ T lymphocytes <200 x 10(6)/I (56%, 50%). The third category corresponded to patients with > 500 x 10(6)/I (53.3%). CONCLUSIONS: Viral replication and SI phenotype, independently, are useful markers for severity of HIV infection. The biological differences among NSI of the 3 viral phenotype categories, including the new subgroup NSI/SI, may indicate the existence of more pathogenic NSI subpopulations.

Adolescent↗
PubMed1998

[Invasive fungal infections in liver transplant recipients: analysis of 21 cases].

BACKGROUND: Invasive fungal infections (IFI) are one of the most important causes of mortality in liver transplant (LT) recipients. The aim of this study was to describe the characteristics of IFI in the LT program of our institution with an special emphasis in the differences between Candida infections (CI) and that caused by other fungi (NCI). PATIENTS AND METHODS: Retrospective analysis of the hospital charts of 21 patients who underwent a LT from February 1987 to December 1995. The diagnosis of IFI required the histological evidence of tissue invasion or a positive culture in a tissue sample or in an usually sterile fluid. Esophageal candidiasis was not considered as IFI. Antifungal prophylaxis was performed either with nystatin or fluconazole. RESULTS: Twenty-one of 356 patients (6%) developed a total of 23 episodes of IFI. Pathogens were Candida spp. (n = 10), Aspergillus (n = 8), Zygomicetes (n = 4) and Cryptococcus (n = 1). Fifty-seven percent of the episodes of IFI (80% of those caused by Candida and 38% of those produced by other fungi; p < 0.05) developed in the first 3 months after transplantation and only 5 episodes appeared after the sixth month. The diagnosis of IFI was done at autopsy in 6 patients (29%). Overall, NCI (13 episodes) predominated over CI (10 episodes), being the later the cause of the 54% of the episodes in the first 178 recipients but only the 30% in the last 178 patients (p = 0.09). No differences were found in the distribution of the risk factors amongst those patients with CI or NCI. Seventeen of the 21 patients (71%) died and 15 of these deaths (72%) were attributable to fungi; 15 patients who died either did not receive amphotericin (n = 6) or received a cumulative dose lower than 500 mg. Six patients received a cumulative dose of more than 1.5 g (mean, 3.2 g) and four of them were cured. Mortality in the nonfungal infection group was 26% (p < 0.001). CONCLUSIONS: IFI was a rare but severe complication in our LT recipients. The relative frequency of CI was progressively decreasing during the study period, being NCI the predominant infections. Amphotericin therapy was effective only when a high cumulative dose could be administered.

Adult↗
PubMed1998

Structural features of the combining site region of Erythrina corallodendron lectin: role of tryptophan 135.

The role of Trp 135 and Tyr 108 in the combining site of Erythrina corallodendron lectin (ECorL) was investigated by physicochemical characterization of mutants obtained by site-directed mutagenesis, hemagglutination-inhibition studies, and molecular modeling, including dynamics simulations. The findings demonstrate that Trp 135 in ECorL: (1) is required for the tight binding of Ca2+ and Mn2+ to the lectin because mutation of this residue into alanine results in loss of these ions upon dialysis and concomitant reversible inactivation of the mutant; (2) contributes to the high affinity of methyl alpha-N-dansylgalactosaminide (MealphaGalNDns) to the lectin; and (3) is solely responsible for the fluorescence energy transfer between the aromatic residues of the lectin and the dansyl group in the ECorL-MealphaGalNDns complex. Docking of MealphaGalNDns into the combining site of the lectin reveals that the dansyl moiety is parallel with the indole of Trp 135, as required for efficient fluorescence energy transfer, in one of the two possible conformations that this ligand assumes in the bound state. In the W135A mutant, which still binds MealphaGalNDns strongly, the dansyl group may partially insert itself into the place formerly occupied by Trp 135, a process that from dynamics simulations does not appear to be energetically favored unless the loop containing this residue assumes an open conformation. However, a small fraction of the W135A molecules must be able to bind MealphaGalNDns in order to explain the relatively high affinity, as compared to galactose, still remaining for this ligand. A model for the molecular events leading to inactivation of the W135A mutant upon demetallization is also presented in which the cis-trans isomerization of the Ala 88-Asp 89 peptide bond, observed in high-temperature dynamics simulations, appears not to be a required step.

Acetylgalactosamine↗
PubMed1998

Hilar biliary cysts in hepatic transplantation. Report of three symptomatic cases and occurrence in resected liver grafts.

Hilar cysts are infrequent post-transplant biliary tract complications. Thirteen cases were discovered among 493 consecutive liver transplants (2.6%). Three (0.60%) were symptomatic (obstructive jaundice) while the other ten were found by systematically searching in the hilum in a series of 129 consecutive, resected grafts at retransplantation or autopsy (n = 54). Two types of cysts were detected: in eight grafts (1.6%), these were blind unilocular cavities with viscid mucous content, located adjacent to the biliary tract anastomoses. These had been inadvertently created as a result of the sequestered remnant cystic duct after cholecystectomies and biliary tract reconstructions, where a double-barreled common duct and long cystic duct had been present in the donor liver. These mucoceles ranged from 0.5 to 5.5 cm in diameter (median 1.7 cm). The three symptomatic cases were diagnosed by imaging techniques 3.5 years after transplantation; however, this type of cyst was found as early as the 2nd month post-transplantation when detected in lost liver grafts. Five livers (1%), lost between 5 months and 2.8 years post-transplantation, showed cystically dilated peribiliary glands, sometimes with multilocular, and occasionally multiple, cavities ranging from 0.5 to 2 cm in diameter (median 0.8 cm). This type of cyst was asymptomatic and located adjacent to the left, right, or common hepatic ducts. Threads were found near four cysts, suggesting that surgical injury may have been responsible for obstructing the neck of the glands. With the increasing number of long-term survivors of liver transplantation, unless preventive surgical methods are implemented, the number of symptomatic cysts of these origins can be expected to grow. Transplantation teams should, therefore, be aware of these potential causes of biliary tract complications.

Adolescent↗
PubMed1998

Lipid abnormalities in stable liver transplant recipients--effects of cyclosporin, tacrolimus, and steroids.

Dyslipidemia is common after liver transplantation, but the underlying mechanisms are largely unknown. We studied the lipid profile of 27 liver transplant recipients randomized to received either cyclosporin (CyA, n = 14) or tacrolimus (n = 13) and compared them with 20 healthy, matched controls. Before transplantation, patients presented low total and low-density lipoprotein (LDL) cholesterol (as compared to controls) that increased shortly, i.e., 3 months, after transplantation. Eighteen months post-transplantation, total and LDL cholesterol levels decreased to pre-transplant values but tended to remain higher in CyA-treated patients. However, at that time, prednisone treatment was more prevalent among CyA-treated than tacrolimus-treated patients and fully accounted for the difference in cholesterol levels. Indeed, regardless of therapy, patients not receiving prednisone exhibited lower cholesterol levels than prednisone-treated patients and controls. We conclude that prednisone therapy, rather than CyA or tacrolimus immunosuppression, seems to be the major determinant of increased cholesterol levels.

Adult↗