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Biomedical subjects

M Aguilar

Publications and source records attributed to M Aguilar.

At least 37 records · Page 2Linked to original sources
PubMed2001

[A model of primary prevention of sexually transmitted diseases and HIV/AIDS in adolescents].

OBJECTIVE: To develop, apply, and evaluate an educational model for the primary prevention of sexually transmitted diseases (STDs) and acquired immunodeficiency syndrome (AIDS) that was based on the sexual knowledge, attitudes, and practices (KAPs) of adolescents and on their perceptions and behaviors in this area, with the ultimate goal of helping develop educational tools to prevent infection with STDs and the human immunodeficiency virus (HIV). METHODS: An STD/HIV/AIDS primary prevention model was applied with adolescent schoolchildren (12 to 15 years old) in the canton of Santo Domingo de los Colorados, Ecuador. Two groups with similar characteristics were formed: the experimental group, with 358 students, and the control group, with 288 students. Schools were selected according to inclusion criteria, and adolescents at each school were chosen at random. A discussion guide was applied with 16 focus groups, and the resulting information was used to prepare a KAP survey. After being validated, the KAP survey was applied to the experimental group and to the control group. A prevention education program geared to students and teachers was implemented with the experimental group. Eight months later a second KAP survey was done with the experimental group and the control group. The differences in KAPs before and after the intervention were evaluated using the chi-square test. RESULTS: There were no statistically significant differences between the two groups before the intervention, but afterwards the differences were statistically significant (P = 0.012), with an increase in the knowledge of sexuality and STDs/AIDS in the experimental group, even though the long-term behavior changes have not been evaluated. CONCLUSIONS: This study validated a multifactorial STD/AIDS prevention model adapted to the reality of adolescents, and it suggests the possibility of extrapolating this experience more broadly to contexts similar to those of this Ecuador population.

Adolescent↗
PubMed2001

[Consensus conference on consultation times in neurology. Recommendations on consultation times in neurology outpatients care in Spain].

INTRODUCTION: Developing recommendations about consultation times in neurology helps plan the endowment of human resources and can contribute to homogenize and improve quality of health-care. OBJECTIVES: To elaborate recommendations on the consultation times needed to obtain enough quality neurology visits. MATERIAL AND METHOD: We used consensus search techniques, in particular the Community Impression technique. An ad hoc committee developed a preliminary proposal which was later discussed during a unlimited attendance working meeting and eventually voted by members of the Spanish Society of Neurology. The committee drew up a final consensus report after analysing the debate results and counting the ballots. FINAL RECOMMENDATION: "It is necessary that the Spanish Society of Neurology establishes and recommends standardized consultation times for neurology outpatients visits in Spain. These standardized values refer to consultation time per patient, both in the first and follow-up visits, in a General Neurology Outpatients Clinic. Moreover, there must be considered 'recommendable times' on one hand, and 'minimal required times' on the other hand. Any time value below the minimal required time means that the consultation duration does not fulfill the minimal requirements needed to warrant a care with acceptable quality for the patient". These recommendations are: Time for first consultation. Recommendable time: 45 minutes (Minimal required time: 25 minutes). Time for follow-up consultation. Recommendable time: 20 minutes (Minimal required time: 15 minutes).

Humans↗
PubMed2000

Albendazole treatment of children with ascariasis enhances the vibriocidal antibody response to the live attenuated oral cholera vaccine CVD 103-HgR.

Because concurrent infections with geohelminth parasites might impair the immune response to oral vaccines, we studied the vibriocidal antibody response to the oral cholera vaccine CVD 103-HgR in children infected with Ascaris lumbricoides and investigated the effect of albendazole pretreatment on the postvaccination response. Children with ascariasis were randomized to receive either 2 sequential doses of 400 mg of albendazole or placebo. After the second dose, CVD 103-HgR was given, and serum vibriocidal antibody levels were measured before and 10 days after vaccination. Postvaccination rates of seroconversion were greater in the treatment group that received albendazole (P=.06). Significantly greater rates of seroconversion and geometric mean titer were observed in the albendazole group in subjects with non-O ABO blood groups. A significant association was observed between vibriocidal seroconversion rates and treatment group, suggesting that A. lumbricoides infections impair the immune response to oral cholera vaccine, particularly in subjects of non-O blood groups.

Adolescent↗
PubMed2000

Allantoate amidinohydrolase (Allantoicase) from Chlamydomonas reinhardtii: its purification and catalytic and molecular characterization.

An allantoate-degrading enzyme has been purified to electrophoretic homogeneity for the first time from a photosynthetic organism, the unicellular green algae Chlamydomonas reinhardtii. The purification procedure included a differential protein extraction followed by conventional steps such as ammonium sulfate fractionation, gel filtration, anion exchange chromatography, and preparative electrophoresis. Under the routine assay conditions (7 mM allantoate), specific activity for the purified enzyme was 185 U/mg, which rose to 225 U/mg under kinetic considerations (saturating substrate). Therefore, a turnover number of 4.5 x 10(4) min(-1) can be deduced for the 200-kDa protein. The enzyme is a true allantoicase (EC 3.5.3.4) that catalyzes the degradation of allantoate to (-)ureidoglycolate and (+)ureidoglycolate to glyoxylate. The enzyme exhibited hyperbolic kinetic for allantoate and ureidoglycolate with K(m) values of 2 and 0.7 mM, respectively. V(max) of the reaction with allantoate as substrate was nine times higher than that with ureidoglycolate. The native enzyme has a molecular weight of 200 kDa and consists of six identical or similar-sized subunits of 34 kDa each, organized in two trimers of 100 kDa. Each subunit has five cysteine residues, four of which are involved in disulfide bonds, with a total of 12 disulfide bonds in the 200-kDa protein. Allantoate inhibits competitively the reaction with ureidoglycolate as substrate. In addition, buffers and group-specific reagents affect the activity in the same manner irrespective of the substrate used. Those results suggest that both substrates use the same active site. The effect of group-specific reagents suggest that the amino acids histidine, tyrosine, and cysteine are essentials for the allantoicase activity with both substrates.

Amino Acids↗
PubMed2000

Clinical parameters (body mass index and age) are the best predictors for the need of insulin therapy during the first 18 months of diabetes mellitus in young adult patients.

To address the question whether there are simple clinical predictors of need for insulin in the first 18 months of treatment of diabetes presenting in young adult subjects, a prospective study of 24 patients with diabetes mellitus (age: 18-40 years) was designed. At diagnosis of diabetes, age, sex, body mass index (BMI), glycemia, ketonuria, C-peptide, insulin autoantibodies, islet cell antibodies and glutamic acid decarboxylase antibodies were recorded before starting any treatment. At the end of the follow-up (18 +/- 4 months), they were divided into two groups according to their need for insulin therapy: group 1 (n=15; 62%), who needed insulin therapy, and group 2 (n=9; 38%), who did not. Each marker was related to actual need for therapy necessity. Multivariate analysis showed that BMI and age were the variables with greatest predictive value regarding need for insulin. These data reveal that the need for insulin therapy in young adult diabetic patients may be supported by the clinical criteria of age and BMI, which are both easily and quickly determined.

Adolescent↗
PubMed2000

Inactivation of MS-2 phage and poliovirus in groundwater.

Since temperature affects the inactivation rate of viruses in natural water systems, the aim of this study was to determine if a temperature shift could influence the structural integrity of model viruses. When crude lysates of MS-2 phage were seeded into groundwater microcosms and incubated at 27 degrees C, complete virus inactivation took place in eight days. The temperature was then shifted to 4 degrees C. Three days after the temperature shift, a two-log increase in virus titer (reactivation) occurred. However, when purified MS-2 lysates were added to groundwater microcosms, no reactivation was obtained. No reactivation of poliovirus took place when similar microcosm experiments were done. The sedimentation coefficients of MS-2 shifted from 80S to 58S, 48S, 37S, 32S, and 18S as inactivation proceeded in groundwater and distilled water controls. Similarly, the sedimentation coefficients of polioviruses changed from 156S to 142S, 135S, 117S, 105S, 95S, and 80 S as inactivation took place. There was no correlation between % virus inactivation and % decrease in virions with intact sedimentation coefficients, as reported earlier for poliovirus inactivated by chlorine. The results presented support our hypothesis that virus inactivation proceeds gradually, involving the rearrangement and (or) loss of capsomere components that may eventually lead to the ejection of nucleic acids. The intermediate particles generated as inactivation proceeds may be in a reversibly inactivated state, and may revert back to a fully infectious state when chemical components stabilize the virus particle.

Fresh Water↗
PubMed2000

[Plasma levels of insulin and leptin in patients with morbid obesity and anorexia nervosa after weight loss or gain, respectively].

The present study was conducted in order to analyze the relationship existing between leptin and insulin levels in massive weight loss and weight recovery. Thirteen patients with severe obesity, 14 patients with anorexia nervosa and 13 healthy control subjects were studied. The patients with severe obesity underwent a vertical banded gastroplasty followed by an 800 kcal/day diet for 12 weeks. They were evaluated prior to (body mass index [BMI] 51.2 +/- 8.8 Kg/m2) and after drastic weight loss (BMI 40.6 +/- 6.7 Kg/m2). Patients with anorexia nervosa were treated exclusively with nutritional therapy during 12 weeks, and they were evaluated at their lowest weight status (BMI 16.2 +/- 2.2 Kg/m2) and after weight recovery (BMI 17.9 +/- 2.3 Kg/m2). The BMI of the normal subjects was in the normal range of 20 to 27 Kg/m2 (average 22.8 +/- 2.6 Kg/m2). BMI, percentage of body fat, waist circumference, and serum levels of leptin, insulin, and C-peptide were determined in each patient and normal subject. In severely obese patients, serum leptin and insulin decreased significantly after drastic weight reduction (leptin: from 51.8 +/- 22.3 to 23.7 +/- 10.2 ng/ml; insulin: from 27.1 +/- 13.3 to 17.2 +/- 7.2 mU/ml). In patients with anorexia nervosa, the mean serum leptin levels were significantly higher after weight recovery (5.5 +/- 3.2 vs 7.6 +/- 6 ng/ml). Serum leptin in the severe obesity group correlated positively with BMI, percentage body fat and waist circumference before and after weight loss. In those patients suffering from anorexia nervosa, serum leptin correlated positively with the BMI, percentage of body fat, and waist circumference in the low weight state and after weight recovery. In addition, their serum insulin correlated with BMI and waist circumference after weight recovery. These data reveal that serum leptin concentration correlates significantly with the BMI and body fat content 1) in subjects with a range of weight and caloric intake, 2) in obese patients after drastic weight loss; 3) in anorexic patients after weight gain; and that hyper- or normoinsulinemia do not seem to have any influence on the leptin changes caused by weight loss or gain.

Adipose Tissue↗
PubMed2000

Growth hormone and thyrotropin hormone secretion in Alzheimer's disease.

The present study examined the relationship among GH and TSH secretion and neuropsychological and morphological tests in patients with Alzheimer's disease (AD). We studied 28 healthy controls and 28 AD patients with psychoneurological tests, and correlated their data with morphological data obtained by computed tomography and hormone responses of GH to GHRH, and TSH to TRH. The GH response to GHRH was higher in AD patients than in controls, 12.2 +/- 2 vs. 5.2 +/- 2.1 mcg/l, p< 0.01 but there was no difference in TSH response to TRH. On neuropsychological tests, patients were classified into 3 stages, these were indistinguishable on the basis of morphological data, GH and TSH responses at all stages including early-onset. Although GH response to GHRH was higher in AD patients than in controls, our results suggest that psychometric discrimination may be more accurate in diagnosis and staging of AD, than in predicting by morphological and hormonal responses.

Aged↗
PubMed1999

Lipid-induced conformation and lipid-binding properties of cytolytic and antimicrobial peptides: determination and biological specificity.

While antimicrobial and cytolytic peptides exert their effects on cells largely by interacting with the lipid bilayers of their membranes, the influence of the cell membrane lipid composition on the specificity of these peptides towards a given organism is not yet understood. The lack of experimental model systems that mimic the complexity of natural cell membranes has hampered efforts to establish a direct correlation between the induced conformation of these peptides upon binding to cell membranes and their biological specificities. Nevertheless, studies using model membranes reconstituted from lipids and a few membrane-associated proteins, combined with spectroscopic techniques (i.e. circular dichroism, fluorescence spectroscopy, Fourier transform infra red spectroscopy, etc.), have provided information on specific structure-function relationships of peptide-membrane interactions at the molecular level. Reversed phase-high performance chromatography (RP-HPLC) and surface plasmon resonance (SPR) are emerging techniques for the study of the dynamics of the interactions between cytolytic and antimicrobial peptides and lipid surfaces. Thus, the immobilization of lipid moieties onto RP-HPLC sorbent now allows the investigation of peptide conformational transition upon interaction with membrane surfaces, while SPR allows the observation of the time course of peptide binding to membrane surfaces. Such studies have clearly demonstrated the complexity of peptide-membrane interactions in terms of the mutual changes in peptide binding, conformation, orientation, and lipid organization, and have, to a certain extent, allowed correlations to be drawn between peptide conformational properties and lytic activity.

Animals↗
PubMed1999

Spectrophotometric quantitation of antioxidant capacity through the formation of a phosphomolybdenum complex: specific application to the determination of vitamin E.

A spectrophotometric method has been developed for the quantitative determination of antioxidant capacity. The assay is based on the reduction of Mo(VI) to Mo(V) by the sample analyte and the subsequent formation of a green phosphate/Mo(V) complex at acidic pH. The method has been optimized and characterized with respect to linearity interval, repetitivity and reproducibility, and molar absorption coefficients for the quantitation of several antioxidants, including vitamin E. The phosphomolybdenum method, in combination with hexane monophasic extraction, has also been adapted for the specific determination of vitamin E in seeds. The results obtained with the proposed method were validated by comparison with a standard HPLC method. The phosphomolybdenum method is routinely applied in our laboratory to evaluate the total antioxidant capacity of plant extracts and to determine vitamin E in a variety of grains and seeds, including corn and soybean.

Antioxidants↗
PubMed1999

RT-PCR cloning, characterization and mRNA expression analysis of a cDNA encoding a type II asparagine synthetase in common bean.

Following a RT-PCR strategy based on the design of degenerate oligonucleotides resembling conserved domains of asparagine synthetase (AS; EC 6.3.5.4), we isolated a 2 kb cDNA clone (PVAS2) from root tissue of the common bean (Phaseolus vulgaris). PVAS2 encodes a protein of 584 amino acids with a predicted relative molecular mass of 65810 Da, an isoelectric point of 6.4, and a net charge of -7.2 at pH 7.0. The amino acid sequence of the protein encoded by PVAS2 is very similar to that encoded by the soybean SAS2 asparagine synthetase gene. The amino-terminal residues of the predicted PVAS2 protein are identical to the amino acids that constitute the glutamine-binding (GAT) domain of AS from other plant species, which suggests that the PVAS2 cDNA encodes a type II glutamine-dependent form of asparagine synthetase. Southern blot analysis indicates that the common bean AS is part of a small family composed of at least two genes. Expression analysis by Northern blot revealed that the PVAS2 transcript accumulates to a high level in roots and, to a lesser extent, in nodules and developing pods. Accumulation of the PVAS2 transcript in the root seems to be negatively regulated by light and sucrose, and positively regulated by nitrate.

Amino Acid Sequence↗
PubMed1999

[Factors influencing the prescription of insulin and oral antidiabetics in primary care].

OBJECTIVES: To analyse the prescription of insulin and oral diabetic medication (ODM) in primary health care, and to evaluate which variables, depending on the prescribing doctor, work-place or population attended, explain quality and/or quantity variations in prescription. DESIGN: Crossover, observational study. SETTING: Málaga-Este Health District, Málaga. PARTICIPANTS: 21,166 prescriptions issued by 144 doctors in the Málaga-Este Health District during the first quarter of 1997 were analysed. MEASUREMENTS AND MAIN RESULTS: Insulin consumption of 10.63 defined daily doses per 1,000 inhabitants and day (DID) and ODM of 18.51 DID were calculated. No significant differences were observed in insulin or ODM prescription for sex, and few for age, job or doctors' specialty via MIR (intern) training. Working in a centre with MIR teaching and in a reformed centre were significantly associated with a greater use of insulin (p < 0.0001 and p < 0.02, respectively). Having a higher allocation of patients drawing pensions meant a greater consumption of insulin (p < 0.01) and even more of ODM (p < 0.0001). The population allocated being older was associated with greater consumption of ODM without any changes in insulin prescription. CONCLUSIONS: The personal features of doctors working in primary care affect very little the quantity and quality of insulin and ODM prescription. The characteristics of the work-place (reformed centre and centre entitled to teach) and the population attended (older and drawing a pension) are the main factors conditioning the amount of prescription of insulin and ODM, respectively. Nevertheless, in all cases ODM prescription quality is low.

Administration, Oral↗
PubMed1999

Experimental designs and response surface modeling applied for the optimization of metal-cyanide complexes analysis by capillary electrophoresis.

The development of capillary zone electrophoresis (CZE) methods for the determination of metal cyanide complexes in real samples showed some problems, such as the low detection signal of Au (CN)2- and the low resolution between Ni(II) and Fe(II) cyanides in gold processing solutions, and the lack of separation of Pt(CN)4(2-) and Pd(CN)4(2-) in the leachates from automobile catalytic converters. To optimize some analytical parameters, the present study thus focused on the application of experimental designs and multiregression models. The following factors were examined by a two-level factorial design: applied voltage, injection time, detection wavelength, buffer ion, ionic strength and buffer modifiers. For optimization of the CZE method, subsequent response-surface experiments with the important factors were made with the two kinds of leaching solutions. Optimal analytical conditions were obtained in each case, giving good detection signals and resolution for the components of the studied leachates.

Cyanides↗
PubMed1999

Relationship of arithmetic problem solving and reflective-impulsive cognitive styles in third-grade students.

Different individuals approach mathematical problems in a variety of ways, with these different approaches also reflected in over-all cognitive styles. This investigation had two purposes, first, to determine whether good and poor arithmetic problem solvers differ substantially in cognitive style, and second, to determine whether the students, after training in techniques of solving arithmetic problems, improve their performance with no significant change in cognitive style. A total of 98 third graders participated (mean age 8.1 yr.; 50 boys, 48 girls). The Matching Familiar Figure Test was used to classify the students by cognitive style as either Reflective or Impulsive. Students also were given training with different problem-solving exercises for different arithmetic problems. The training program in problem-solving strategies did not improve performance on arithmetic problems for Reflective students; however, Impulsive students' performance did improve after training.

Child↗
PubMed1998

Acute lower respiratory infections due to respiratory syncytial virus and adenovirus among hospitalized children from Argentina.

BACKGROUND: Acute lower respiratory infection (ALRI) is one of the main causes of morbidity and mortality in small children. OBJECTIVE: The aim of this study was to determine the frequency, seasonality and association with clinical entities of respiratory syncytial virus (RSV) and adenoviruses in children with ALRI. STUDY DESIGN: During 2 consecutive years (1991-1992), 168 children under 2 years of age hospitalized due to ALRI in a public pediatric hospital of Buenos Aires, Argentina, were studied. RSV and adenoviruses were investigated on nasopharyngeal aspirates (NPA) by indirect immunofluorescence (IIF). HEp-2 cells were used for adenovirus isolation. RESULTS: RSV was detected in 36.3% and adenoviruses in 14.3% of the cases (P < 0.0001). All adenoviruses detected by IIF were also isolated in culture. Out of 61 RSV cases, 57% corresponded to bronchiolitis and 43% to pneumonia. Ninety-two per cent of children with RSV were less than 1 year old and 70% were less than 5 months. The highest number of RSV cases were observed during winter, with a clear peak in July. Seventy-one per cent of adenovirus cases were associated with pneumonia and only 24% with bronchiolitis (P < 0.02), and predominated in children older than 5 months of age (P < 0.0001). Adenoviruses were detected in almost all months of the year with a small peak at the end of winter and beginning of spring. No significant differences in clinical features at admission, breast feeding or malnutrition were observed among children with RSV or adenovirus diagnosis versus those with no viral etiology. The overall fatality rate was 2.4%. In all fatal cases adenovirus was detected in NPA. Thus, fatality rate among patients with adenoviruses reached 16.7%. CONCLUSIONS: Our findings show the importance of RSV and adenoviruses associated with ALRI in hospitalized children under 2 years of age and the different epidemiological patterns of the two viruses in Buenos Aires, Argentina.

Acute Disease↗