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Biomedical subjects

E Román

Publications and source records attributed to E Román.

At least 19 recordsLinked to original sources
PubMed2006

The MAP kinase signal transduction network in Candida albicans.

MAP (mitogen-activated protein) kinase-mediated pathways are key elements in sensing and transmitting the response of cells to environmental conditions by the sequential action of phosphorylation events. In the fungal pathogen Candida albicans, different routes have been identified by genetic analysis, and especially by the phenotypic characterization of mutants altered in the Mkc1, Cek1/2 and Hog1 MAP kinases. The cell integrity (or MKC1-mediated) pathway is primarily involved in the biogenesis of the cell wall. The HOG pathway participates in the response to osmotic stress while the Cek1 pathway mediates mating and filamentation. Their actual functions are, however, much broader and Mkc1 senses several types of stress, while Hog1 is also responsive to other stress conditions and participates in two morphogenetic programmes: filamentation and chlamydospore formation. Furthermore, it has been recently shown that Cek1 participates in a putative pathway involved in the construction of the cell wall and which seems to be operative under basal conditions. As these stimuli are frequently encountered in the human host, they provide a reasonable explanation for the significant reduction in pathogenicity that several signal transduction mutants show in certain animal models of virulence. MAPK pathways therefore represent an attractive multienzymic system for which novel antifungal therapy could be designed.

Adaptation, Physiological↗
PubMed2006

The Cek1 and Hog1 mitogen-activated protein kinases play complementary roles in cell wall biogenesis and chlamydospore formation in the fungal pathogen Candida albicans.

The Hog1 mitogen-activated protein (MAP) kinase mediates an adaptive response to both osmotic and oxidative stress in the fungal pathogen Candida albicans. This protein also participates in two distinct morphogenetic processes, namely the yeast-to-hypha transition (as a repressor) and chlamydospore formation (as an inducer). We show here that repression of filamentous growth occurs both under serum limitation and under other partially inducing conditions, such as low temperature, low pH, or nitrogen starvation. To understand the relationship of the HOG pathway to other MAP kinase cascades that also play a role in morphological transitions, we have constructed and characterized a set of double mutants in which we deleted both the HOG1 gene and other signaling elements (the CST20, CLA4, and HST7 kinases, the CPH1 and EFG1 transcription factors, and the CPP1 protein phosphatase). We also show that Hog1 prevents the yeast-to-hypha switch independent of all the elements analyzed and that the inability of the hog1 mutants to form chlamydospores is suppressed when additional elements of the CEK1 pathway (CST20 or HST7) are altered. Finally, we report that Hog1 represses the activation of the Cek1 MAP kinase under basal conditions and that Cek1 activation correlates with resistance to certain cell wall inhibitors (such as Congo red), demonstrating a role for this pathway in cell wall biogenesis.

Candida albicans↗
PubMed2005

Self-assembled monolayers of peptide nucleic acids on gold surfaces: a spectroscopic study.

We have characterized self-assembled monolayers (SAMs) of thiol-derivatized peptide nucleic acid (PNA) chains adsorbed on gold surfaces by using reflection absorption infrared spectroscopy (RAIRS) and X-ray photoemission spectroscopy (XPS) techniques. We have found that the molecular orientation of PNAs strongly depends on surface coverage. At low coverage, PNA chains lie flat on the surface, while at high coverage, PNA molecules realign their molecular axes with the surface normal and form SAMs without the need of co-immobilization of spacers or other adjuvant molecules. The change in the molecular orientation has been studied by infrared spectroscopy and it has been confirmed by atomic force microscopy (AFM). PNA immobilization has been followed by analyzing the N(1s) XPS core-level peak. We show that the fine line shape of the N(1s) core-level peak at optimal concentration for biosensing is due to a chemical shift. A combination of the above-mentioned techniques allow us to affirm that the structure of the SAMs is stabilized by molecule-molecule interactions through noncomplementary adjacent nucleic bases.

Chromatography, High Pressure Liquid↗
PubMed2005

[Left renal vein hypertension syndrome].

INTRODUCTION: [corrected] Left renal vein compression, causing retrograde hypertension, determines a syndrome characterized by the presence of hematuria, gonadal vein dilatation and varicocele. Being a rare cause of hematuria its aetiology is diverse but of precise characteristics. Diagnosis is not easy and treatment requires to rule out its precise aetiology and consider the intensity of the compression phenomenon because of interventionist attitudes have important implications and are not risk free. MATERIAL AND METHODS: We report nine children, aged 8-15 years, presenting with hematuria of urologic characteristics. Diagnosis of left renal vein hypertension or nutcracker phenomenon was established through ultrasound (regular and doppler-ultrasound) and helical-TC performed in all, and left renal venography performed in six of them. RESULTS: Retroaortic renal vein was present in two cases, a varicose accessorial renal vein due to anomalous drainage in one and compression at the aortomesenteric space in six. Because of the symptoms severity therapeutic attitude was interventionist in two cases, performing an auto-transplantation in one, and endovascular stent placement al the level of the left renal vein compression in other. CONCLUSIONS: Diagnosis of this syndrome is not always easy because less invasive explorations usually show parameters that are difficult to distinguish from normality. Severity of clinical manifestations and therapeutic attitude are related with the presence of renal vein hyperpressure and collateral varicose circulation indicating the lack of compensation of a difficult drainage.

Adolescent↗
PubMed2004

Ordered self-assembled monolayers of Peptide nucleic acids with DNA recognition capability.

We report on the formation of ordered self-assembled monolayers (SAMs) of single-stranded peptide nucleic acids (ssPNA). In spite of their remarkable length (7 nm) thiolated PNAs assemble standing up on gold surfaces similarly to the SAMs of short alkanethiols. SAMs of ssPNA recognize complementary nucleic acids, acting as specific biosensors that discriminate even a point mutation in target ssDNA. These results are obtained by surface characterization techniques that avoid labeling of the target molecule: x-ray photoemission, x-ray absorption and atomic force microscopy.

DNA, Single-Stranded↗
PubMed2004

[Mesangial glomerulonephritis and intermediate uveitis].

Uveitis in children are less frequent than in adults. Their prognosis is variable because it may be found as an isolated and idiophatic condition or in association with definite clinical entities. The associated noninfectious diseases with predominantly renal involvement are tubulointerstitial nephritis and uveitis syndrome (TINU syndrome), mesangial glomerulonephritis isolated or in association with Behçet's disease. A case of 14-years-old girl with intermediate uveitis (pars planitis) and mesangial glomerulonephritis is presented. The ocular symptoms was eye redness and ocular pain and she has snow-banks in pars plana. She showed microscopic hematuria and intermitent proteinuria that increased during the ocular clinical exacerbation. Renal biopsy revealed both mild mesangial matrix increase and mesangial celullarity with normal tubulointerstitial structure and mesangial deposition of IgA and IgG immunoglobulins. This case is de first pediatric patient report in the literature with intermediate uveitis and mesangial glomerulonephritis with immune deposition. Mesangial glomerulonephritis were observed in patients whit Behçet disease, known etiological cause of uveitis in adults and children. These findings may suggest that uveitis and glomerulonephritis have common immunological pathogenesis including circulatory immune complexes. In uveitis patients, screening for associated extra-ocular and renal manifestations is mandatory and should have careful long-term follow-up with regular systemic evaluation.

Adolescent↗
PubMed2003

Strategies for the identification of virulence determinants in human pathogenic fungi.

The incidence of fungal infections is increasing in different countries. The current available therapy of these infections does not satisfy all requirements in terms of specificity and therapeutic index, a fact that has stimulated the scientific community to identify fungal virulence determinants. Several pathogenic fungi are opportunistic and, therefore, identification of virulence genes is difficult, given their close relationship with host cells. In recent years, the development of genetic tools in several pathogenic fungi has enabled the development of genetic strategies for their identification. These include several strategies based on the phenotypic analysis of strains or environmental conditions in which the expression of the putative gene(s) is either altered or deleted; and this is accomplished through the development of in vitro or in vivo systems. In the near future, this research will produce a better picture of fungal pathogenesis and therefore define novel promising targets in antifungal therapy.

Fungi↗
PubMed2001

Phase transfer of hydrophilic, cyclodextrin-modified gold nanoparticles to chloroform solutions.

The preparation and characterization of gold nanoparticles (approximately 3 nm in diameter) capped with thiolated alpha- and beta-cyclodextrins (alpha and beta-CD) is described. The CD-capped nanoparticles are hydrophilic and bind ferrocene derivatives as evidenced by electrochemical and (1)H NMR spectroscopic measurements. The binding interactions of the CD-capped nanoparticles with a series of five alkyldimethyl(ferrocenylmethyl)ammonium ions (the alkyl group is propyl for compound 1, heptyl for 2, dodecyl for 3, hexadecyl for 4, and docosyl for 5) can be utilized for the phase transfer of the hydrophilic, CD-capped nanoparticles into a nonpolar chloroform phase. Only 3, 4, and 5 act as effective phase transfer agents, since 1 and 2 do not have enough amphiphilic character. The structure of the aggregates formed upon transfer of the CD-capped nanoparticles to the chloroform solution is postulated to resemble that of reverse micelles, as the nanoparticles template the peripheral arrangement of the cationic ferrocene amphiphiles, counterions and water molecules around their surfaces.

Journal Article↗
PubMed2001

Expanding cavitand chemistry: the preparation and characterization of [n]cavitands with n>=4.

The preparation of cavitands composed of 4, 5, 6, and 7 aromatic subunits ([n]cavitands, n=4-7) is described. The simple, two-step synthetic procedure utilized readily available starting materials (2-methylresorcinol and diethoxymethane). The two cavitand products having 4 and 5 aromatic subunits exhibited highly symmetric cone conformations, while the larger cavitands (n = 6 and 7) adopt conformations of lower symmetry. 1H NMR spectroscopic studies of [6]cavitand and [7]cavitand revealed that these hosts undergo exchange between equivalent conformations at room temperature. The departure of these two cavitands from cone conformations is related to steric crowding on their Ar-O-CH2-OAr bridges and is predicted by simple molecular mechanics calculations (MM2 force field). X-ray diffraction studies on single crystals of the [4]cavitand, [5]cavitand, and [6]cavitand hosts afforded additional experimental support for these conclusions.

Ethers, Cyclic↗
PubMed2001

Signal transduction pathways and cell-wall construction in Candida albicans.

Signal transduction pathways are the molecular mechanisms responsible for detecting and transmitting changes in the surrounding environment to the nucleus where appropriate responses are generated. The cell wall is the most external structure of the fungal cell and, in pathogenic fungi, is responsible for specifically interacting with the mammalian host cell in a highly dynamic interplay. Recent work has shown the role that some signal transduction pathways, involving members of the MAP kinase family, have in this process in the nonpathogenic model organism Saccharomyces cerevisiae. However, as yet little is known about these phenomena in pathogenic fungi. The aim of this review is to characterize the existing signal transduction pathways in Candida albicans and their relationship with the cell-wall construction.

Candida albicans↗
PubMed2000

Causes of death of patients with multiple injuries in Debrecen, Hungary.

OBJECTIVE: To find out the main causes of death of people who had multiple severe injuries. DESIGN: Retrospective study. SETTING: Teaching hospital, Hungary. SUBJECTS: 86 people with severe multiple injuries, of whom 59 died and had necropsies. MAIN OUTCOME MEASURE: Establishment of a database. RESULTS: Consumption of alcohol was a common precursor. Head and chest injuries predominated. More pedestrians than people in vehicles were killed, and there were 8 suicides and 3 murders. There were no gunshot injuries. CONCLUSIONS: Reduction of deaths from multiple injuries is as much a socioeconomic as a medical matter.

Alcohol Drinking↗
PubMed2000

[Caroli's syndrome. Report of a case beginning in childhood with favorable course].

Caroli's disease is a rare entity that is included in the fibropolycystic abnormalities of the bile ducts. Ultrasonographic patterns consist of evident dilatation of the bile ducts. Although it is thought to be a congenital disease, it usually presents in young adults and few cases have been reported in children. We present the case of a 10-year-old boy with Caroli's syndrome (Caroli's disease, congenital hepatic fibrosis and polycystic renal disease). Evolution was favorable.

Age of Onset↗
PubMed1999

Interaction of a monoclonal antibody against hEGF with a receptor site for EGF.

Epidermal growth factor (EGF) has been detected by radioimmunoassay (RIA) in different body fluids such as serum, amniotic fluid, and urine. Human tumor tissues with EGF receptors (EGF-Rc) may be saturated with EGF, which may be of prognostic value. An RIA was envisaged to measure human epidermal growth factor (hEGF) levels using EGF-Rc as capture agent and a monoclonal antibody anti-hEGF (MAb anti-hEGF) labeled with 125Iodine as a marker for this binding. The purpose of this work was to study the feasibility of MAb anti-hEGF to detect the receptor binding sites and to investigate the interaction between MAb anti-hEGF and the EGF-Rc. Various binding experiments were performed to study possible interference and interactions in the complex MAb anti-hEGF and the receptor. Affinity constants were determined by means of Scatchard plot analysis to interpret the complex stability challenged with other compounds for a better understanding of the interaction process. Binding constants were of the same order for all the ligands tested separately involving the EGF-Rc, but were significantly higher (t = 15.7, p < 0.05) for hEGF in its binding to MAb anti-hEGF. It was possible with equilibrium studies and competition experiments to evaluate the interaction of EGF and MAb anti-hEGF with the EGF receptor. This observation makes the MAb anti-hEGF a potential tracer for the quantitation of receptors in vitro, and possibly for the detection of membrane receptors on tumor cells in vivo.

Animals↗
PubMed1996

Synthetic peptides non-covalently bound to bacterial hsp 70 elicit peptide-specific T-cell responses in vivo.

We have examined the immunogenicity of complexes formed by non-covalent association of a synthetic peptide corresponding to influenza A virus nucleoprotein, residues 206-229 (pNP) and Mycobacterium tuberculosis heat-shock protein 70 (hsp 70). One or two injections of these complexes given to BALB/c mice without any additional adjuvant, were capable of eliciting very strong peptide-specific proliferative T-cell responses in the spleen. These responses were dependent on the stability of the complex since immunogenicity was lost when dissociated with ATP prior to immunization. T-cell responses to hsp 70 were easily generated by immunization with the purified chaperone alone, either after primary or secondary immunization. Injection of pNP-hsp 70 complexes, however, although generating good primary responses, resulted in very much decreased proliferative responses to the hsp 70.

Adenosine Triphosphate↗
PubMed1996

[Nutrient and food consumption by ages and gender in school children from the Community of Madrid (CAENPE)].

UNLABELLED: The objective of the present work was to know the consume of foodstuffs and nutrients among schoolchildren in the Madrid Autonomous Community and also the relative contribution of each group of foodstuffs to the overall intake of macronutrients. This study had a sectional observational design involving 2,608 children (51% males and 49% females) with ages ranging from 6 to 14 years who were randomly recruited from conglomerate of schools, according to socio-economic status and rural/urban residence. The inquiry on nutrients in 4 non consecutive days was analyzed (2 "24 hour-recall" and 2 "intake recall"). RESULTS: a) the consume of proteins, lipids, and carbohydrates represented 17%, 43% and 40% of the total caloric value, respectively; b) the intake of meats, sausages, sweets, tidbits, and processed products was very high. This fact is in origin of the excessive total and saturated lipid intake; c) there was a scarce intake of vegetables, cereals and potatoes among children of all ages and dairy products in children older than 12 years; d) the intake of legumes, eggs and fruits was appropriate; e) males consumed proportionally higher amounts than females of the following groups of foodstuffs: cereals, sweets and tidbits. The consume of meat, sausages, fish, eggs, potatoes, dry fruits and dairy products was similar in both sexes. Females consumed proportionally more fat foodstuffs, vegetables, fruits, legumes and processed products; f) females consumed a diet with a still higher lipid and protein content than males. These findings can serve as a basis to develop educational guidelines with a practical impact on family and school menus.

Adolescent↗
PubMed1995

H-2-associated effects of flanking residues on the recognition of a permissive mycobacterial T-cell epitope.

Previously we have identified an immunodominant, eight-residue, epitope core sequence (TAAGNVNI) from the 19,000 MW protein of Mycobacterium tuberculosis, which is recognized in the context of multiple H-2 I-A molecules. In this study, the role of residues flanking this T-cell epitope core was examined, using a series of 20 mer analogue peptides in which the native flanking residues were progressively replaced with L-alanine. Analogue peptides were tested for their capacity to stimulate a CD4+ 19,000 MW protein-specific T-cell line, revealing that all but one N-terminal flanking residue could be replaced collectively by alanine without significant loss of stimulatory activity. However, clear H-2-associated differences in the requirement for flanking residues were demonstrated with peptide-specific T-cell hybridomas. In particular, H-2d-derived hybridomas were much more stringent in their requirement for flanking residues than were H-2b hybridomas. All polyalanine-substituted peptides bound I-Ab molecules, with affinities similar to the native unsubstituted peptide. In contrast, significantly reduced binding to I-Ad was observed with several analogue peptides, although without a clear relationship to the degree of substitution. Furthermore, in H-2b mice, neither immunogenicity nor cross-reactivity with the native peptide showed a clear inverse relationship with respect to the degree of alanine substitution. The results presented in this paper indicate that flanking residues can influence T-cell specificity and that these effects may be controlled by major histocompatibility complex (MHC) haplotype.

Alanine↗
PubMed1994

Mapping of Hsp70-binding sites on protein antigens.

Hsp70-binding sites were mapped on three antigens, the 16-, 19- and 38-kDa proteins of Mycobacterium tuberculosis, using overlapping synthetic peptides in a competitive-binding assay. In each protein, two or three prominent hsp70-binding sites were identified when peptides 20-amino-acid long were used, predominantly in regions containing clusters of aliphatic amino acids. Although there was an overall concordance in the pattern of peptide binding to hsp70 from bacterial (M. tuberculosis) and mammalian sources (immunoglobulin heavy-chain-binding protein), some differences in the specificity of polypeptide binding and the effect of peptides on ATPase activity were observed.

Adenosine Triphosphatases↗