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Biomedical subjects

A Gonzalez

Publications and source records attributed to A Gonzalez.

At least 73 records · Page 4Linked to original sources
PubMed2000

Follow-up of steroid-resistant nephrotic syndrome: tubular proteinuria and enzymuria.

The aim of this study was to examine the compromise of proximal tubule cells in steroid-resistant nephrotic syndrome patients with a histologic diagnosis of focal segmental glomerulosclerosis (FSGS) through assessment of the urinary levels of beta 2-microglobulin (beta 2M) and N-acetyl-beta-D-glucosaminidase (NAG) during active disease and remission over a follow-up period of 3 years. We studied 34 children with nephrotic syndrome: 12 with steroid-resistant nephrotic syndrome (SRNS) and massive proteinuria, 7 with steroid-dependent nephrotic syndrome (SDNS) and 15 with steroid-sensitive nephrotic syndrome (SSNS). Of the SSNS patients, 8 children were in remission (RM) and 7 were in relapse (RL). Seven healthy children were included as controls. Urinary beta 2M, measured by enzyme-linked immunosorbent assay, was significantly increased in the SRNS group as compared to the SDNS group (P < 0.01), SSNS in remission (P < 0.01), and controls (P < 0.01). There were no differences between the SRNS group and SSNS in relapse. Analysis of urinary N-acetyl-beta-D-glucosaminidase (U-NAG) by colorimetric assay showed significantly higher values in the SRNS group of patients than in SDNS, SSNS, and control groups. A positive correlation between U-NAG and proteinuria was demonstrated (r = 0.73, P < 0.01). The SRNS group of patients (n = 12, 11 with a histologic diagnosis of FSGS and one with diffuse mesangial proliferation) was treated with the same protocol of i.v. methylprednisone and oral cyclophosphamide. Long-term follow-up showed a progressive decrease in U-beta 2M and U-NAG excretion to control values in the 3rd year, except in one patient who did not respond to the treatment. In the FSGS patients, evaluation of the contribution of structural interstitial histological abnormalities, including each of the histological parameters considered in interstitial scarring to the functional tubule abnormalities assessed by beta 2M and NAG excretion, was performed by multiple regression analysis. The r2 values for beta 2M and NAG were 53.99%, P = 0.19, and 57.90%, P = 0.14, respectively; neither was significant. We conclude that: (1) proximal tubule cell dysfunction, partially affected by massive albuminuria, may account for the higher values of beta 2M and NAG excretion in the SRNS patients and (2) urine beta 2M and NAG levels are not helpful in identifying histological evidence of structural tubulointerstitial damage in children with steroid-resistant nephrotic syndrome.

Acetylglucosaminidase↗
PubMed2000

The Spanish National Reference Database for Ionizing Radiations (BANDRRI)

The Spanish National Reference Database for Ionizing Radiations (BANDRRI) is being implemented by a reasearch team in the frame of a joint project between CIEMAT (Unidad de Metrologia de Radiaciones Ionizantes and Direccion de Informatica) and the Universidad Nacional de Educacion a Distancia (UNED, Departamento de Mecanica y Departamento de Fisica de Materiales). This paper presents the main objectives of BANDRRI, its dynamic and relational data base structure, interactive Web accessibility and its main radionuclide-related contents at this moment.

Journal Article↗
PubMed2000

Primary costochondritis due to Escherichia coli.

We present a case of primary costochondritis by Escherichia coli, in a diabetic woman. The patient suffered a urinary infection by E. coli which may have been the source of haematogenous spread. She received medical and surgical therapy and 5 months later, she was asymptomatic.

Aged↗
PubMed2000

Prosody impairment in depression measured through acoustic analysis.

This work attempts to explore the association between depression and prosody impairment through acoustic techniques of voice analysis. For this purpose, we selected 10 quantitative vocal parameters, obtained instrumentally, and related to the variability and psychomotor control of phonation, which we have considered as prosody indicators. The sample consisted of 23 patients with diagnosis DSM-III-R of major depression and a control group of 20 healthy volunteers. We obtained results in 7 of the 10 acoustic parameters that suggest reduced prosody in depressed subjects. In a second voice test, carried out 2 months after baseline situation, and while patients were under antidepressant treatment, it was not possible to demonstrate that all these prosody indicators change to normality in those 13 subjects who clinically improved.

Adolescent↗
PubMed2000

Fluid flow induced by nonuniform ac electric fields in electrolytes on microelectrodes. I. Experimental measurements

Under the influence of an ac electric field, electrolytes on planar microelectrodes exhibit fluid flow. The nonuniform electric field generated by the electrodes interacts with the suspending fluid through a number of mechanisms, giving rise to body forces and fluid flow. This paper presents the detailed experimental measurements of the velocity of fluid flow on microelectrodes at frequencies below the charge relaxation frequency of the electrolyte. The velocity of latex tracer particles was measured as a function of applied signal frequency and potential, electrolyte conductivity, and position on the electrode surface. The data are discussed in terms of a linear model of ac electroosmosis: the interaction of the nonuniform ac field and the induced electrical double layer.

Journal Article↗
PubMed2000

Fluid flow induced by nonuniform ac electric fields in electrolytes on microelectrodes. II. A linear double-layer analysis

Frequency-dependent fluid flow in electrolytes on microelectrodes subjected to ac voltages has recently been reported. The fluid flow is predominant at frequencies of the order of the relaxation frequency of the electrode-electrolyte system. The mechanism responsible for this motion has been termed ac electro-osmosis: a continuous flow driven by the interaction of the oscillating electric field and the charge at the diffuse double layer on the electrodes. This paper develops the basis of a theoretical approach to this problem using a linear double layer analysis. The theoretical results are compared with the experiments, and a good correlation is found.

Journal Article↗
PubMed2000

Density functional theory of long-range critical wetting

The wetting properties of a fluid adsorbed at a solid substrate are studied by means of density functional theory. Explicit calculations of the substrate-liquid and substrate-gas density profiles are carried out and used to evaluate the asymptotic expansion for the interface potential of a system with long-range interactions. The range of validity of the asymptotic expansion is checked by comparing it with the interface potential obtained numerically through the constrained minimization of the density functional free energy. Depending on the parameters of the fluid-fluid and substrate-fluid interactions we find first-order or critical wetting transitions. In a limited range of parameters, the critical wetting transition is preceded by a first-order transition between a microscopic and a mesoscopic film, thus corroborating previous calculations and experiments for alkanes on brine. We find that the behavior of the alkanes on brine is not universal, since it requires fine-tuning of the fluid-fluid and substrate-fluid interactions. Finally, we investigate the influence of the short- and long-range forces on the location of the first-order transition. We find that for the models studied, the long-range forces cannot be treated perturbatively. Thus for this type of model it is not possible to separate the effects of short- and long-range forces as done in Landau theories, where the long-range forces are treated perturbatively.

Journal Article↗
PubMed2000

Nitric oxide may contribute to nocturnal hemodynamic changes in cirrhotic patients.

OBJECTIVE: Patients with liver cirrhosis have a nocturnal worsening of hemodynamic parameters that has been associated with an increased risk of variceal bleeding at nighttime. The aim of this study was to investigate whether nitric oxide and cytokines are implicated in these hemodynamic changes. METHODS: Ten cirrhotic patients and eight controls were studied. Mean blood pressure, heart rate, plasma norepinephrine, tumor necrosis factor alpha and interleukin-6 levels, and serum nitrite + nitrate levels were determined at 0800, 1600, and 2400 h. All determinations were performed in supine rest and at least 4 h after meals. In a second study, nitrite + nitrate levels were assessed in 10 cirrhotic patients before and after eating a standard meal. RESULTS: Mean arterial pressure levels that were always lower in the patient group showed a nocturnal decrease in both groups of subjects. Heart rate values that were always higher in cirrhotic patients showed a nocturnal fall in controls, whereas cirrhotics maintained elevated values at nighttime. Norepinephrine levels were higher in cirrhotics and maintained similar values during the study, whereas controls had a significant nocturnal decrease. Nitrite + nitrate levels that were higher in cirrhotic patients showed a significant mean increase of 40% from morning (0800 h) to night (2400 h) in the patient group, whereas in controls no change was observed (p < 0.05). Tumor necrosis factor alpha and interleukin-6 levels did not change either in patients or controls during the entire period. Cirrhotic patients with or without ascites maintained a pattern of hemodynamic and biochemical changes similar to the pattern observed in the entire group of patients. Finally, no changes in serum nitrite + nitrate levels were observed in patients before and after eating the standard meal. CONCLUSION: An increased nocturnal nitric oxide production might contribute to the hemodynamic changes observed in cirrhotic patients during nighttime.

Aged↗
PubMed2000

Nitric oxide participation in the fungicidal mechanism of gamma interferon-activated murine macrophages against Paracoccidioides brasiliensis conidia.

Paracoccidioidomycosis, a systemic mycosis restricted to Latin America and produced by the dimorphic fungus Paracoccidioides brasiliensis, is probably acquired by inhalation of conidia produced by the mycelial form. The macrophage (Mphi) represents the major cell defense against this pathogen; when activated with gamma interferon (IFN-gamma), murine Mphis kill the fungus by an oxygen-independent mechanism. Our goal was to determine the role of nitric oxide in the fungicidal effect of Mphis on P. brasiliensis conidia. The results revealed that IFN-gamma-activated murine Mphis inhibited the conidium-to-yeast transformation process in a dose-dependent manner; maximal inhibition was observed in Mphis activated with 50 U/ml and incubated for 96 h at 37 degrees C. When Mphis were activated with 150 to 200 U of cytokine per ml, the number of CFU was 70% lower than in nonactivated controls, indicating that there was a fungicidal effect. The inhibitory effect was reversed by the addition of anti-IFN-gamma monoclonal antibodies. Activation by IFN-gamma also enhanced Mphi nitric oxide production, as revealed by increasing NO(2) values (8 +/- 3 microM in nonactivated Mphis versus 43 +/- 13 microM in activated Mphis). The neutralization of IFN-gamma also reversed nitric oxide production at basal levels (8 +/- 5 microM). Additionally, we found that there was a significant inverse correlation (r = -0.8975) between NO(2)(-) concentration and transformation of P. brasiliensis conidia. Additionally, treatment with any of the three different nitric oxide inhibitors used (arginase, N(G)-monomethyl-L-arginine, and aminoguanidine), reverted the inhibition of the transformation process with 40 to 70% of intracellular yeast and significantly reduced nitric oxide production. These results show that IFN-gamma-activated murine Mphis kill P. brasiliensis conidia through the L-arginine-nitric oxide pathway.

Animals↗
PubMed2000

Prevalence and risk factors of tinea unguium and tinea pedis in the general population in Spain.

This study prospectively evaluated the prevalence and risk factors of tinea unguium and tinea pedis in the general adult population in Madrid, Spain. One thousand subjects were clinically examined, and samples of nails and scales from the interdigital spaces of the feet were taken from those patients presenting with signs or symptoms of onychomycosis and/or tinea pedis, respectively. In addition, a sample from the fourth interdigital space of both feet was collected from all individuals with a piece of sterilized wool carpet. Tinea unguium was defined as a positive direct examination with potassium hydroxide and culture of the etiological agent from subjects with clinically abnormal nails. Patients with positive dermatophyte cultures of foot specimens were considered to have tinea pedis. The prevalence of tinea unguium was 2.8% (4.0% for men and 1.7% for women), and the prevalence of tinea pedis was 2.9% (4.2% for men and 1.7% for women). The etiological agents of tinea unguium were identified as Trichopyton rubrum (82.1%), followed by Trichopyton mentagrophytes var. interdigitale (14.3%) and Trichopyton tonsurans (3.5%). Trichophyton rubrum (44.8%) and Trichophyton mentagrophytes (44.8%), followed by Epidermophyton floccosum (7%) and T. tonsurans (3.4%), were the organisms isolated from patients with tinea pedis. The percentage of subjects who suffered simultaneously from both diseases was 1.1% (1.7% for men and 0.6% for women). In a multivariate logistic regression analysis, age (relative risk [RR], 1.03) and gender (RR, 2.50) were independent risk factors for tinea unguium, while only gender (RR, 2.65) was predictive for the occurrence of tinea pedis. In both analyses, the presence of one of the two conditions was associated with a higher risk for the appearance of the other disease (RR, >25).

Adult↗
PubMed2000

Identification of a short, hydrophilic amino acid sequence critical for origin recognition by the bovine papillomavirus E1 protein.

The E1 protein of bovine papillomavirus (BPV) is a site-specific DNA binding protein that recognizes an 18-bp inverted repeat element in the viral origin of replication. Sequence-specific DNA binding function maps to the region from approximately amino acids 140 to 300, and isolated polypeptides containing this region have been shown to retain origin binding in vitro. To investigate the sequence and structural characteristics which contribute to sequence-specific binding, the primary sequence of this region was examined for conserved features. The BPV E1 DNA binding domain (E1DBD) contains three major hydrophilic domains (HR1, amino acids 179-191; HR2, amino acids 218 to 230; and HR3, amino acids 241 to 252), of which only HR1 and HR3 are conserved among papillomavirus E1 proteins. E1DBD proteins with lysine-to-alanine mutations in HR1 and HR3 were severely impaired for DNA binding function in vitro, while a lysine-to-alanine mutation in HR2 had a minimal effect on DNA binding. Mutation of adjacent threonine residues in HR1 (T187 and T188) revealed that these two amino acids made drastically different contributions to DNA binding, with the T187 mutant being severely defective for origin binding whereas the T188 mutant was only mildly affected. Helical wheel projections of HR1 predict that T187 is on the same helical face as the critical lysine residues whereas T188 is on the opposing face, which is consistent with their respective contributions to DNA binding activity. To examine E1 binding in vivo, a yeast one-hybrid system was developed. Both full-length E1 and the E1DBD polypeptide were capable of specifically interacting with the E1 binding site in the context of the yeast genome, and HR1 was also critical for this in vivo interaction. Overall, our results indicate that HR1 is essential for origin binding by E1, and the features and properties of HR1 suggest that it may be part of a recognition sequence that mediates specific E1-nucleotide contacts.

Amino Acid Sequence↗
PubMed2000

Enteric locus of action of prokinetics: ABT-229, motilin, and erythromycin.

We investigated the in vivo and in vitro locus of actions of prokinetics: motilin, erythromycin, and ABT-229. The test substances were infused close intra-arterially in short segments of the jejunum in the intact conscious state. Each prokinetic acted on a presynaptic neuron and utilized at least one nicotinic synapse to stimulate circular muscle contractions. The final neurotransmitter at the neuroeffector junction was ACh. Motilin and erythromycin, but not ABT-229, also released nitric oxide. Each prokinetic utilized somewhat different subtypes of muscarinic, serotonergic, tachykininergic, and histaminergic receptors, except for the M(3) receptor, which was common to all of them. In contrast, none of the prokinetics stimulated contractions in mucosa-free or mucosa-attached muscle strips, or rings, even though methacholine or electrical field stimulation induced phasic contractions in all of them. The prokinetics also did not release ACh in longitudinal muscle-myenteric plexus preparations. Each prokinetic, however, decreased the length of enzymatically dispersed single cells. In conclusion, each prokinetic may act on a different subset of presynaptic neurons that converge on the postsynaptic cholinergic and nonadrenergic noncholinergic motoneurons. The presynaptic neurons may be impaired in the muscle bath environment.

Animals↗
PubMed1999

A street deposit sampling method for metal and hydrocarbon contamination assessment.

Urban surface contamination, by atmospheric deposits as well as human activities, is a major concern for urban pollution management. Besides coarse street deposits which are clearly perceived and easily removed, suspended solid (SS) surface loads and contamination by heavy metals and hydrocarbons are rarely assessed although they could be of major importance with regards to combined or separate server overflow (CSO and SSO) impacts. Both dry and wet vacuum sampling procedures have been first compared, in the laboratory, using dry and sieved clay or street deposits. Then the wet vacuum sampling procedure has been refined, coupling the injection of water and the hand-brushing of the surface prior to its vacuum cleaning, and evaluated on a car parking area close to the University. Finally this procedure has been assessed in Béarn Street within the 'Le Marais' district in Paris centre, and 34 samples have been analysed for metal and eight for aromatic hydrocarbon contamination. Heavy metal concentrations (0.1-1.7 g kg-1 dry wt. Cu, 0.9-6.1 g kg-1 dry wt. Pb and 1.5-4.6 g kg-1 dry wt. Zn) within street deposit samples collected in Paris centre, indicate a high contamination, especially for copper and zinc, as compared to reported data. Total polyaromatic hydrocarbons (PAHs) are in the 3-11 mg kg-1 dry wt. range, thus approximately 10 times less contaminated than dry atmospheric deposits. This paper presents data obtained and discusses the difficulties encountered when sampling street deposits in busy areas of a city like Paris. The water jet street cleaning procedure used by Paris city workers was tested for its efficiency, by comparison of surface loads before and after the cleaning procedure. Although solids cleaning efficiency is highly variable (20-65%) and somewhat higher for particles larger than 100 microns, particulate metal cleaning efficiency is even more variable (0-75%) and particulate PAHs appear not to be significantly removed.

Environmental Pollutants↗
PubMed1999

The crystal structure of anthranilate synthase from Sulfolobus solfataricus: functional implications.

Anthranilate synthase catalyzes the synthesis of anthranilate from chorismate and glutamine and is feedback-inhibited by tryptophan. The enzyme of the hyperthermophile Sulfolobus solfataricus has been crystallized in the absence of physiological ligands, and its three-dimensional structure has been determined at 2.5-A resolution with x-ray crystallography. It is a heterotetramer of anthranilate synthase (TrpE) and glutamine amidotransferase (TrpG) subunits, in which two TrpG:TrpE protomers associate mainly via the TrpG subunits. The small TrpG subunit (195 residues) has the known "triad" glutamine amidotransferase fold. The large TrpE subunit (421 residues) has a novel fold. It displays a cleft between two domains, the tips of which contact the TrpG subunit across its active site. Clusters of catalytically essential residues are located inside the cleft, spatially separated from clustered residues involved in feedback inhibition. The structure suggests a model in which chorismate binding triggers a relative movement of the two domain tips of the TrpE subunit, activating the TrpG subunit and creating a channel for passage of ammonia toward the active site of the TrpE subunit. Tryptophan presumably blocks this rearrangement, thus stabilizing the inactive states of both subunits. The structure of the TrpE subunit is a likely prototype for the related enzymes 4-amino 4-deoxychorismate synthase and isochorismate synthase.

Amino Acid Sequence↗
PubMed1999

Pantropic retroviral vectors mediate gene transfer and expression in Entamoeba histolytica.

Transformation of Entamoeba histolytica has been previously reported, but the foreign genes have all been replicated episomally. Pantropic retroviral vectors based on the Moloney murine leukemia virus with the envelope glycoprotein of vesicular stomatitis virus (VSV-G) have an extremely broad host range and can be concentrated to high titer. To investigate whether these pseudotyped, pantropic vectors can mediate gene transfer and expression in E. histolytica, we constructed a retroviral vector, in which a hygromycin phosphotransferase is expressed from the E. histolytica actin promoter. Data confirm the infection, integration, and expression of a foreign gene mediated by the provirus. To our knowledge, this is the most evolutionarily distant example of successful integration and expression of a mammalian retrovirus. Pantropic retroviral vectors may thus facilitate genetic analysis in species lacking transformation systems.

Animals↗
PubMed1999

Glycans in post-Golgi apical targeting: sorting signals or structural props?

A recent model proposed that N-glycans serve as apical targeting signals for soluble and membrane proteins in epithelial cells and neurons by interacting with lectin sorters in the trans-Golgi network. However, we believe that a number of experimental observations support an alternative hypothesis, that N-glycans play a facilitative role, by providing structural support or preventing aggregation of the proteins for example, thereby allowing interaction of proteinaceous apical sorting signals with the sorting machinery. This article discusses the experimental data currently available and how they relate to the proposed models.

Animals↗