Biomedical subjects

M Araujo

Publications and source records attributed to M Araujo.

At least 19 recordsLinked to original sources

PubMed2006

Urinary NO3 excretion and renal failure in indinavir-treated patients.

Treatment with indinavir (IDV), a protease inhibitor, is frequently associated with renal abnormalities. We determined the incidence of renal failure (creatinine clearance <80 mL min-1 1.73 (m(2))-1) in HIV patients treated with highly active antiretroviral therapy, including IDV, and investigated the possible mechanisms and risk factors of IDV nephrotoxicity. Thirty-six patients receiving IDV were followed for 3 years. All were assessed for age, body weight, duration of infection, duration of IDV treatment, sulfur-derivative use, total cholesterol, triglycerides, magnesium, sodium, potassium, creatinine, and urinalysis. We also determined renal function in terms of creatinine clearance, urine osmolality and fractional excretion of sodium, potassium, and water. Urinary nitrate (NO3) excretion was measured in 18 IDV-treated patients and compared with that of 8 patients treated with efavirenz, a drug without renal side effects. Sterile leukocyturia occurred in 80.5% of the IDV-treated patients. Creatinine clearance <80 mL min-1 1.73 (m(2))-1 was observed in 22 patients (61%) and was associated with low body weight and the use of sulfur-derivatives. These patients also had lower osmolality, lower urine volume and a higher fractional excretion of water compared to the normal renal function group. Urinary NO3 excretion was significantly lower in IDV-treated patients (809 +/- 181 microM NO3-/mg creatinine) than in efavirenz-treated patients (2247 +/- 648 microM NO3-/mg creatinine, P < 0.01). The lower NO3 excretion suggests that IDV decreases nitric oxide production.

Adult↗

PubMed2005

Inactivation of Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa and Staphylococcus aureus on stainless steel and glass surfaces by neutral electrolysed water.

AIM: To ascertain the efficacy of neutral electrolysed water (NEW) in reducing Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes on glass and stainless steel surfaces. Its effectiveness for that purpose is compared with that of a sodium hypochlorite (NaClO) solution with similar pH, oxidation-reduction potential (ORP) and active chlorine content. METHODS AND RESULTS: First, the bactericidal activity of NEW was evaluated over pure cultures (8.5 log CFU ml-1) of the abovementioned strains: all of them were reduced by more than 7 log CFU ml-1 within 5 min of exposure either to NEW (63 mg l-1 active chlorine) or to NaClO solution (62 mg l-1 active chlorine). Then, stainless steel and glass surfaces were inoculated with the same strains and rinsed for 1 min in either NEW, NaClO solution or deionized water (control). In the first two cases, the populations of all the strains decreased by more than 6 log CFU 50 cm-2. No significant difference (P<or=0.05) was found between the final populations of each strain with regard to the treatment solutions (NEW or NaClO solution) or to the type of surface. CONCLUSIONS: NEW was revealed to be as effective as NaClO at significantly reducing the presence of pathogenic and spoilage bacteria (in this study, E. coli, L. monocytogenes, P. aeruginosa and S. aureus) on stainless steel and glass surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: NEW has the advantage of being safer than NaClO and easier to handle. Hence, it represents an advantageous alternative for the disinfection of surfaces in the food industry.

Colony Count, Microbial↗

PubMed2004

Free energy balance for three fluid phases in a capillary of arbitrarily shaped cross-section: capillary entry pressures and layers of the intermediate-wetting phase.

In this work we derive rigorously the free energy balance for three fluid phases in a straight capillary of arbitrarily shaped cross-section. This balance is then used to derive the general equation for the capillary entry pressures of all possible two-phase and three-phase displacements. Moreover, the equation provides the criterion determining the existence of layers of the intermediate-wetting phase separating the wetting and non-wetting phases in the corners or cavities of a capillary, by also treating the spreading of such layers as a capillary displacement. For a number of combinations of interfacial tensions and contact angles, illustrating all the different relevant situations, we calculate the criteria for spreading of such a layer in the corner of a capillary with polygonal cross-section. In a capillary with a cross-section in the shape of an isosceles triangle of varying corner size, these criteria are used to determine the unique capillary entry pressures for piston-like displacement from alternative solutions of the general equation. These solutions relate to displacements in the presence or absence of layers in the various differently sized corners.

Journal Article↗

PubMed2004

Enumeration of Clostridium perfringens spores in groundwater samples: comparison of six culture media.

In order to investigate the ability of Fluorocult-supplemented TSC agar (TSCF (Fluorocult supplemented TSC-agar): prepared from Tryptose Sulfite Cycloserine Agar Base (Merck), D-cycloserine (Fluka Chemika, USA), and fluorocult TSC-Agar supplement (Merck)) for detecting spores of Clostridium perfringens in water, we analyzed groundwater samples, pretreated by heating to 80 degrees C/5 min, using this fluorogenic medium together with five other media: mCP agar (Panreac; Cultimed), TSC agar (Merck, Germany), TSN agar (Merck), and SPS agar (BBL, USA) by the membrane filtration technique, and Wilson-Blair agar (WB) following the still-in-force Spanish official method. Variance analysis of the data obtained shows statistically significant differences in the counts obtained between media employed in this work. The C. perfringens spore counts on mCP agar were significantly lower (P<0.05) than the corresponding values of TSC, TSCF, SPS, and WB media. No statistically significant differences were found between C. perfringens spore counts on TSCF compared with those of other methods used. On the other hand, the identification of typical and atypical colonies isolated from all media demonstrated that fluorogenic TSC agar was the most specific medium for C. perfringens spore recovery in groundwater samples. Additionally, the results obtained indicate that mCP agar, which is the reference method in the European Union, is not suitable medium for recovering C. perfringens spores from groundwater samples.

Clostridium perfringens↗

PubMed2003

Inactivation of Escherichia coli O157:H7, Salmonella enteritidis and Listeria monocytogenes on the surface of tomatoes by neutral electrolyzed water.

AIMS: To determine the efficacy of neutral electrolyzed water (NEW) in killing Escherichia coli O157:H7, Salmonella enteritidis and Listeria monocytogenes, as well as nonpathogenic E. coli, on the surface of tomatoes, and to evaluate the effect of rinsing with NEW on the organoleptic characteristics of the tomatoes. METHODS AND RESULTS: The bactericidal activity of NEW, containing 444 or 89 mg l(-1) of active chlorine, was evaluated over pure cultures (8.5 log CFU ml(-1)) of the above-mentioned strains. All of them were reduced by more than 6 log CFU ml(-1) within 5 min of exposure to NEW. Fresh tomatoes were surface-inoculated with the same strains, and rinsed in NEW (89 mg l(-1) of active chlorine) or in deionized sterile water (control), for 30 or 60 s. In the NEW treatments, independent of the strain and of the treatment time, an initial surface population of about 5 log CFU sq.cm(-1) was reduced to <1 log CFU sq.cm(-1), and no cells were detected in the washing solution by plating procedure. A sensory evaluation was conducted to ascertain possible alterations in organoleptic qualities, yielding no significant differences with regard to untreated tomatoes. SIGNIFICANCE AND IMPACT OF THE STUDY: Rinsing in NEW reveals as an effective method to control the presence of E. coli O157:H7, S. enteritidis and L. monocytogenes on the surface of fresh tomatoes, without affecting their organoleptic characteristics. This indicates its potential application for the decontamination of fresh produce surfaces.

Chlorine↗

PubMed2001

Mutagenic potential of bisphenol A diglycidyl ether (BADGE) and its hydrolysis-derived products in the Ames Salmonella assay.

The mutagenicity of bisphenol A diglycidyl ether (BADGE), its first and second hydrolysis products (the diol epoxide and bis-diol of BADGE, respectively) and the bis-chlorohydrin of BADGE were investigated using the Ames Salmonella assay with strains TA98, TA100, TA1535 and TA1537. The assays were performed in the absence and presence of various concentrations of rat liver S9 fraction. The results obtained confirm the mutagenic power of BADGE in strains TA100 and TA1535 and show a positive response to the diol epoxide of BADGE in these strains, although the latter compound was approximately 10 times less potent than the former. A lack of mutagenic activity of the bis-diol of BADGE and the chlorohydrin under study is also shown. These findings suggest that BADGE and, to a much lesser extent, the diol epoxide of BADGE may constitute a genotoxic hazard, but not the bis-diol or bis-chlorohydrin of BADGE.

Animals↗

PubMed2001

Evaluation of fluorogenic TSC agar for recovering Clostridium perfringens in groundwater samples.

Clostridium perfringens is widely recognised as a reliable water pollution indicator. Since several media can be employed for the membrane filtration enumeration of this microorganism, the main aim of this work was to investigate the ability of fluorocult-supplemented TSC-agar (Merck) for recovering Cl. perfringens from public springs used for direct human consumption. Cl. perfringens recovery was also performed on mCP agar (Cultimed) according to Directive 98/83 as well as on TSC-Agar (Merck), TSN-Agar (Merck) and SPS-Agar (BBL) media. Variance analysis of data obtained showed no statistically significant differences in the counts obtained among all media employed in this work. However, the Cl. perfringens recovery efficiencies with TSC and fluorogenic TSC agars were significantly greater (P = < 0.05) than the corresponding values of mCP and TSN media. On the other hand, the identification of typical and atypical colonies isolated from all media demonstrated that fluorogenic TSC agar was the most specific medium for Cl. perfringens recovery in groundwater samples (85.3% of typical colonies and 82.8% of atypical colonies confirmed). In summary, the membrane filtration technique with fluorogenic TSC agar showed the best performance characteristics of all the media tested as judged by their recovery efficiency and specificity in these water samples.

Agar↗

PubMed2001

Evaluation of Coli-ID and MUG Plus media for recovering Escherichia coli and other coliform bacteria from groundwater samples.

Several chromogenic media for detecting coliform bacteria in water are commercially available including Coli ID medium (ID) (bioMérieux) and MUG Plus cefsulodin agar (MP) (Laboratorios Microkit, S.L.). Since little is known about the performance of these media, we have evaluated their usefulness for recovering Escherichia coli and other coliform organisms in groundwaters used for direct human consumption. Variance analysis of obtained data showed that no statistically significant differences in counts of E. coli and other coliforms on ID and MP media compared with reference methods. However, the evaluation of sensitivity and recovery efficiency of both media showed that the two chromogenic media were more sensitive and significantly more efficient (P = < 0.05) than reference medium for detecting coliforms in groundwater. However, the identification of 400 typical and atypical colonies isolated from ID and MP media demonstrated a higher specificity when using ID for coliforms and E. coli. In summary, the two chromogenic media evaluated could be used as alternative methods to reference media for detecting and recovering coliform bacteria in groundwater samples. MP agar was more sensitive and efficient than ID agar whereas the latter was more specific and selective.

Agar↗

PubMed2000

Geometrical Description of Contact Line Fluctuations in Heterogeneous Systems with Controlled Wettability.

The understanding of contact line fluctuations in heterogeneous systems of controlled wettability is relevant to many industrial processes. Despite its importance, it is poorly understood. Here, we present results on an experimental study of fluid displacement on modified Hele-Shaw cells with surface defects as heterogeneities. The system wettability is controlled by defect surface coverage. Three different surface coverage regimes were studied. For each one, the morphology and deformation energy of the displacement front is determined. The width front is described in terms of two exponents, the roughness exponent (alpha) and the one that describes its growth (beta). In all cases, it is found that the width increases logarithmically in time up to a characteristic value, where a crossover to a saturation behavior is observed. The crossover time is a function of the surface coverage. For low coverage 0.51</=beta</=0.59 and 0.65</=alpha</=0.67. For medium and high coverage the values obtained for the exponents are similar to those of directed percolation. The deformation energy associated with the displacement front morphology makes it possible to identify the individual pinning role of the surface defects. Copyright 2000 Academic Press.

Journal Article↗

PubMed2000

A comparison of anaesthesia using remifentanil combined with either isoflurane, enflurane or propofol in patients undergoing gynaecological laparoscopy, varicose vein or arthroscopic surgery.

BACKGROUND: Anaesthesia comprising remifentanil plus isoflurane, enflurane or propofol was randomly evaluated in 285, 285 and 284 patients, respectively, undergoing short-procedure surgery. METHODS: Anaesthesia was induced with propofol (0.5 mg x kg(-1) and 10 mg x 10 s(-1)), and a remifentanil bolus (1 microg x kg(-1)) and infusion at 0.5 microg x g(-1) x min(-1). Five minutes after intubation, remifentanil infusion was halved and 0.5 MAC of isoflurane or enflurane, or propofol at 100 microg x kg(-1) x min(-1) were started and titrated for maintenance. RESULTS: Patient demography and anaesthesia duration were similar between the groups. Surgery was performed as daycases (52%) or inpatients (48%). The median times (5-7 min) to extubation and postoperative recovery were similar between the groups. Responses to tracheal intubation (15% vs 8%) and skin incision (13% vs 7%) were significantly greater in the total intravenous anaesthesia (TIVA) group (P<0.05). Fewer patients given remifentanil and isoflurane (21%) or enflurane (19%) experienced > or =1 intraoperative stress response compared to the TIVA group (28%) (P<0.05). Median times to qualification for and actual recovery room discharge were 0.5-0.6 h and 1.1-1.2 h, respectively. The most common remifentanil-related symptoms were muscle rigidity (6-7%) at induction, hypotension (3-5%) and bradycardia (1-4%) intraoperatively and, shivering (6-7%), nausea and vomiting postoperatively. Nausea (7%) and vomiting (3%) were significantly lower with TIVA compared with inhaled anaesthetic groups (14-15% and 6-8%, respectively; P<0.05). CONCLUSION: Anaesthesia combining remifentanil with volatile hypnotics or TIVA with propofol was effective and well tolerated. Times of extubation, postanaesthesia recovery and recovery room discharge were rapid, consistent and similar for all three regimens.

Adolescent↗

PubMed2000

Efficacy of a diagnostic strategy for patients with chest pain and no ST-segment elevation in the emergency room.

PURPOSE: To evaluate the efficacy of a systematic model of care for patients with chest pain and no ST segment elevation in the emergency room. METHODS: From 1003 patients submitted to an algorithm diagnostic investigation by probability of acute ischemic syndrome. We analyzed 600 ones with no elevation of ST segment, then enrolled to diagnostic routes of median (route 2) and low probability (route 3) to ischemic syndrome. RESULTS: In route 2 we found 17% acute myocardial infarction and 43% unstable angina, whereas in route 3 the rates were 2% and 7%, respectively. Patients with normal/non-specific ECG had 6% probability of AMI whereas in those with negative first CKMB it was 7%; the association of the 2 data only reduced it to 4%. In patients in route 2 the diagnosis of AMI could only be ruled out with serial CKMB measurement up to 9 hours, while in route 3 it could be done in up to 3 hours. Thus, sensitivity and negative predictive value of admission CKMB for AMI were 52% and 93%, respectively. About one-half of patients with unstable angina did not disclose objective ischemic changes on admission. CONCLUSION: The use of a systematic model of care in patients with chest pain offers the opportunity of hindering inappropriate release of patients with ACI and reduces unnecessary admissions. However some patients even with normal ECG should not be released based on a negative first CKMB. Serial measurement of CKMB up to 9 hours is necessary in patients with medium probability of AMI.

Algorithms↗

PubMed2000

Chest pain in the emergency room. Importance of a systematic approach.

OBJECTIVE: To evaluate the efficiency of a systematic diagnostic approach in patients with chest pain in the emergency room in relation to the diagnosis of acute coronary syndrome (ACS) and the rate of hospitalization in high-cost units. METHODS: One thousand and three consecutive patients with chest pain were screened according to a pre-established process of diagnostic investigation based on the pre-test probability of ACS determinate by chest pain type and ECG changes. RESULTS: Of the 1003 patients, 224 were immediately discharged home because of no suspicion of ACS (route 5) and 119 were immediately transferred to the coronary care united because of ST elevation or left bundle-branch block (LBBB) (route 1) (74% of these had a final diagnosis of acute myocardial infarction [AMI]). Of the 660 patients that remained in the emergency room under observation, 77 (12%) had AMI without ST segment elevation and 202 (31%) had unstable angina (UA). In route 2 (high probability of ACS) 17% of patients had AMI and 43% had UA, whereas in route 3 (low probability) 2% had AMI and 7 % had UA. The admission ECG has been confirmed as a poor sensitivity test for the diagnosis of AMI ( 49%), with a positive predictive value considered only satisfactory (79%). CONCLUSION: A systematic diagnostic strategy, as used in this study, is essential in managing patients with chest pain in the emergency room in order to obtain high diagnostic accuracy, lower cost, and optimization of the use of coronary care unit beds.

Journal Article↗

PubMed2000

Chest pain in the emergency room. Importance of a systematic approach

OBJECTIVE: To evaluate the efficiency of a systematic diagnostic approach in patients with chest pain in the emergency room in relation to the diagnosis of acute coronary syndrome (ACS) and the rate of hospitalization in high-cost units. METHODS: One thousand and three consecutive patients with chest pain were screened according to a pre-established process of diagnostic investigation based on the pre-test probability of ACS determinate by chest pain type and ECG changes. RESULTS: Of the 1003 patients, 224 were immediately discharged home because of no suspicion of ACS (route 5) and 119 were immediately transferred to the coronary care united because of ST elevation or left bundle-branch block (LBBB) (route 1) (74% of these had a final diagnosis of acute myocardial infarction [AMI]). Of the 660 patients that remained in the emergency room under observation, 77 (12%) had AMI without ST segment elevation and 202 (31%) had unstable angina (UA). In route 2 (high probability of ACS) 17% of patients had AMI and 43% had UA, whereas in route 3 (low probability) 2% had AMI and 7% had UA. The admission ECG has been confirmed as a poor sensitivity test for the diagnosis of AMI (49%), with a positive predictive value considered only satisfactory (79%). CONCLUSION: A systematic diagnostic strategy, as used in this study, is essential in managing patients with chest pain in the emergency room in order to obtain high diagnostic accuracy, lower cost, and optimization of the use of coronary care unit beds.

Journal Article↗

PubMed2000

Chest pain in the emergency room. Importance of a systematic approach.

OBJECTIVE: To evaluate the efficiency of a systematic diagnostic approach in patients with chest pain in the emergency room in relation to the diagnosis of acute coronary syndrome (ACS) and the rate of hospitalization in high-cost units. METHODS: One thousand and three consecutive patients with chest pain were screened according to a preestablished process of diagnostic investigation based on the pre-test probability of ACS determinate by chest pain type and ECG changes. RESULTS: Of the 1003 patients, 224 were immediately discharged home because of no suspicion of ACS (route 5) and 119 were immediately transferred to the coronary care united because of ST elevation or left bundle-branch block (LBBB) (route 1) (74% of these had a final diagnosis of acute myocardial infarction [AMI]). Of the 660 patients that remained in the emergency room under observation, 77 (12%) had AMI without ST segment elevation and 202 (31%) had unstable angina (UA). In route 2 (high probability of ACS) 17% of patients had AMI and 43% had UA, whereas in route 3 (low probability) 2% had AMI and 7% had UA. The admission ECG has been confirmed as a poor sensitivity test for the diagnosis of AMI (49%), with a positive predictive value considered only satisfactory (79%). CONCLUSION: A systematic diagnostic strategy, as used in this study, is essential in managing patients with chest pain in the emergency room in order to obtain high diagnostic accuracy, lower cost, and optimization of the use of coronary care unit beds.

Aged↗

PubMed1999

Mutation distribution and CYP21/C4 locus variability in Brazilian families with the classical form of the 21-hydroxylase deficiency.

Deficiency of adrenal steroid 21-hydroxylase is the most common form of congenital adrenal hyperplasia and it is considered to be responsible for 90% of the disease. This paper describes for the first time the CYP21B mutation profile in Brazilian patients. We genotyped 41 families with at least one individual affected with the classical form of the 21-hydroxylase deficiency, representing 74 unrelated alleles. In order to characterize different disease-causing alleles, genotyping was performed by Southern blot analysis with three restriction enzymes, allele-specific oligonucleotide hybridization, and allele-specific PCR. Different alleles were distinguished by TaqI C4B RFLP, gene duplications or deletions of either CYP21A + C4B or CYP21B + C4B, large gene conversions and eight mutations that might have been introduced into CYP21B from CYP21A by microconversion events. At least one mutation was detected in 24 different disease-causing alleles, which represents about 85% of the affected alleles in those families. The frequency of the 30 kb deletion of CYP21B was lower than that described for Caucasians. The mutation Sp2 showed the highest frequency (24.65%) and was present mainly in salt-wasting patients, although it was also detected in some patients with the simple virilizing form of the disease. Conversely, I172N showed a frequency of 18.91% and was found mostly in patients affected with the simple virilizing form of the disease. Five other mutations were determined at low frequency, but CL6 was not found in any of the tested alleles.

Adrenal Hyperplasia, Congenital↗

PubMed1999

Spectral statistics and dynamics of Lévy matrices.

We study the spectral statistics and dynamics of a random matrix model where matrix elements are taken from power-law tailed distributions. Such distributions, labeled by a parameter mu, converge on the Lévy basin, giving the matrix model the label "Lévy matrix" [P. Cizeau and J. P. Bouchaud, Phys. Rev. E 50, 1810 (1994)]. Such matrices are interesting because their properties go beyond the Gaussian universality class and they model many physically relevant systems such as spin glasses with dipolar or Ruderman-Kittel-Kasuya-Yosida interactions, electronic systems with power-law decaying interactions, and the spectral behavior at the metal insulator transition. Regarding the density of states we extend previous work to reveal the sparse matrix limit as mu-->0. Furthermore, we find for 2 x 2 Lévy matrices that geometrical level repulsion is not affected by the distribution's broadness. Nevertheless, essential singularities particular to Lévy distributions for small arguments break geometrical repulsion and make it mu dependent. Level dynamics as a function of a symmetry breaking parameter gives new insight into the phases found by Cizeau and Bouchaud (CB). We map the phase diagram drawn qualitatively by CB by using the delta3 statistic. Finally we compute the conductance of each phase by using the Thouless formula, and find that the mixed phase separating conducting and insulating phases has a unique character.

Journal Article↗

PubMed1998

Neural induction in whole chick embryo cultures by FGF.

FGFs are well known as mesodermal inducers and they have been reported to have neural inducing and/or caudalizing activity in Xenopus. To evaluate the role of FGFs in neural induction and patterning of the nervous system in chick embryos, we have targeted the ectopic expression of these factors by applying FGF-soaked beads to extended primitive streak chick embryos developing in culture. The whole embryo culture system allows to directly assessing the neural inducing activity on nonneural ectodermal cells. Our results show that FGFs induce the production of ectopic neural structures in the epiblast cell layer which are independent of the endogenous neural tube. The induced neural plates express several neural positional markers (Otx-2, Krox-20, EphA4, EphA7, and cHox-B9), although they lack anterior neural markers such as BF-1. These effects are very likely to be exerted by the direct action of FGF on epiblast cells because we have found no evidence of the induction of an organizer-like activity or of the presence of new axial mesoderm induced by the growth factor. We conclude that FGFs can act as direct neural inducers and that this action is exerted independently from the axial mesoderm.

Animals↗

PubMed1998

Antigenic diversity of hepatitis B virus strains of genotype F in Amerindians and other population groups from Venezuela.

The adw4 subtype of hepatitis B virus (HBV) belongs to a unique genomic group (genotype F) representing the original HBV strains from the New World. Data regarding the prevalence of this subtype among HBV carriers in South America are, however, scarce, and those concerning HBV genotype F are based on only a few samples from Latin America. In this study, serum samples were obtained from 141 hepatitis B surface antigen (HBsAg) carriers from Amerindians and urban populations from Venezuela. The HBsAg subtype was identified with monoclonal antibodies in 105 samples, and the HBV genotype was identified by reverse-phase hybridization with DNA fragments in 58 samples. The adw4 subtype was highly prevalent in the population studied (75%); among the Amerindians, the prevalence was 97%. The adw2 subtype was also present (10%), while other subtypes (ayw3 and ayw4) were only occasionally found. The HBV subtype was associated with the expected genotype in most cases (80%), and thus genotype F was highly prevalent. Sequencing of viral strains that gave genotypes unpredicted by the HBsAg subtyping confirmed seven of them as belonging to not previously described genotype-subtype associations: namely, adw2 and ayw4 within genotype F.

Amino Acid Substitution↗