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Biomedical subjects

J Vega

Publications and source records attributed to J Vega.

At least 37 records · Page 2Linked to original sources
PubMed2000

Pine processionary caterpillar as a new cause of immunologic contact urticaria.

Nowadays, caterpillars are included among the agents that elicit contact urticaria by a non-immunologic mechanism. Our objective was to find the rôle that an IgE-mediated mechanism could have among patients with suspected contact urticaria from pine processionary caterpillars. 16 patients with suspected contact urticaria from this caterpillar were studied by prick testing and specific IgE detection by immunoblotting. 87% of the patients had a positive prick test and immunoblotting for caterpillar extract. In these allergic patients, the symptoms associated with urticaria were: angioedema (79%), conjunctivitis (36%) and severe anaphylaxis (14%). The most frequent localizations of the wheals were the neck (100%) and forearms (93%). Angioedema was more frequent on the eyelids (79%). The IgE-immunoblot detected in the caterpillar extract several reactive bands, with apparent MWs from to 45 to 4kDa. A total of 5 major allergens were identified, but a band around 14kDa proved to be the dominant allergen. Sensitization to Thaumetopoea pityocampa was found to be the most important mechanism of airborne contact urticaria from this caterpillar. Low-MW proteins are the main IgE binding components of crude caterpillar extract.

Adolescent↗
PubMed2000

Effect of the fine fraction of particulate matter versus the coarse mass and other pollutants on daily mortality in Santiago, Chile.

Daily counts of non-accidental deaths in Santiago, Chile, from 1988 to 1996 were regressed on six air pollutants--fine particles (PM2.5), coarse particles (PM10-2.5), CO, SO2, NO2, and O3. Controlling for seasonal and meteorological conditions was done using three different models--a generalized linear model, a generalized additive model, and a generalized additive model on previously filtered data. Single- and two-pollutant models were tested for lags of 1-5 days and the average of the previous 2-5 days. The increase in mortality associated with the mean levels of air pollution varied from 4 to 11%, depending on the pollutants and the way season of the year was considered. The results were not sensitive to the modeling approaches, but different effects for warmer and colder months were found. Fine particles were more important than coarse particles in the whole year and in winter, but not in summer. NO2 and CO were also significantly associated with daily mortality, as was O3 in the warmer months. No consistent effect was observed for SO2. Given particle composition in Santiago, these results suggest that combustion-generated pollutants, especially from motor vehicles, may be associated with increased mortality. Temperature was closely associated with mortality. High temperatures led to deaths on the same day, while low temperatures lead to deaths from 1 to 4 days later.

Adolescent↗
PubMed2000

[Severe exposure to environmental lead in a child population in Antofagasta, Chile].

BACKGROUND: In Antofagasta, Chile, lead is gathered in bulk in urban zones, contaminating surrounding schools and houses. AIM: To verify if the environmental lead exposure results in high blood lead levels in children living near lead storage sites. MATERIAL AND METHODS: Four hundred eighty-six children under 7 years old, living near lead storage sites and 75 children living far away form these sites, were studied. An inquiry was applied and venous blood was drawn. Air, soil and water lead concentrations were also measured. RESULTS: Lead geometric mean concentrations in exposed children were 8.7 micrograms/dL and 4.22 micrograms/dL in unexposed children. Forty seven percent of exposed children and no unexposed children had lead levels over 10 micrograms/dL. The distance of dwellings from lead storage sites, their geographic location and their antiquity were significantly associated with high blood lead levels. Multivariate models disclosed that people living in contaminated sites have an odds ratio of 24.9 for high blood lead levels. CONCLUSIONS: Environmental lead contamination is significantly associated with high blood lead levels.

Analysis of Variance↗
PubMed1999

Immunogenicity of 2 serogroup B outer-membrane protein meningococcal vaccines: a randomized controlled trial in Chile.

CONTEXT: Meningococcal disease occurs worldwide, and serogroup B disease accounts for a large proportion of cases. Although persons younger than 4 years are at greatest risk for serogroup B meningococcal disease, vaccine efficacy has not been demonstrated in this age group. OBJECTIVE: To evaluate serum bactericidal activity (SBA) against homologous vaccine type strains and a heterologous Chilean epidemic strain of Neisseria meningitidis as a potential correlate for vaccine efficacy. DESIGN: Double-blind, randomized controlled trial conducted between March 14 and July 20, 1994. All blood samples were taken by December 1994. SETTING: Santiago, Chile, where a clonal serogroup B meningococcal disease epidemic began in 1993. PARTICIPANTS: Infants younger than 1 year (n = 187), children aged 2 to 4 years (n = 183), and adults aged 17 to 30 years (n = 173). INTERVENTION: Participants received 3 doses of outer-membrane protein (OMP) meningococcal vaccine developed in either Cuba or Norway or a control vaccine, with each dose given 2 months apart. Blood samples were obtained at baseline, prior to dose 3, and at 4 to 6 weeks after dose 3. MAIN OUTCOME MEASURE: Immune response, defined as a 4-fold or greater rise in SBA titer 4 to 6 weeks after dose 3 compared with prevaccination titer. RESULTS: Children and adult recipients of either meningococcal vaccine were more likely than controls to develop an immune response to the heterologous epidemic strain. After 3 doses of vaccine, 31% to 35% of children responded to the vaccine vs 5% to placebo; 37% to 60% of adults responded to vaccine vs 4% to placebo (P<.05 vs control for all). Infants, however, did not respond. In contrast, against homologous vaccine type strains, the response rate was 67% or higher among children and adults and 90% or higher among infants (P<.001 vs control for all). Subsequent SBA against 7 isogenic homologous target strains identified class 1 OMP as the immunodominant antigen. CONCLUSIONS: These data suggest that neither serogroup B OMP meningococcal vaccine would confer protection during a heterologous epidemic. However, epidemic strain-specific vaccines homologous for class 1 OMP are promising candidates for the control of epidemic serogroup B meningococcal disease.

Adolescent↗
PubMed1999

Molecular characterization of the tight junction protein ZO-1 in MDCK cells.

Most of the information on the structure and function of the tight junction (TJ) has been obtained in MDCK cells. Accordingly, we have sequenced ZO-1 in this cell type, because this protein is involved in the response of the TJ to changes in Ca2+, phosphorylation, and the cytoskeleton. ZO-1 of MDCK cells comprises 6805 bp with a predicted open reading frame of 1769 amino acids. This sequence is 92 and 87% homologous to human and mouse ZO-1, respectively. Two nuclear sorting signals located at the PDZ1 and GK domains and 17 SH3 putative binding sites at the proline-rich domain were detected. We found two new splicing regions at the proline-rich region: beta had not been reported in human and mouse counterparts, and gamma, which was previously sequenced in human and mouse ZO-1, is now identified as a splicing region. The expression of different beta and gamma isoforms varies according to the tissue tested. With the information provided by the sequence, Southern blot, and PCR experiments we can predict a single genomic copy of MDCK-ZO-1 that is at least 13.16 kb long. MDCK-ZO-1 mRNA is 7.4 kb long. Its expression is regulated by calcium, while the expression of MDCK-ZO-1 protein is not.

Alternative Splicing↗
PubMed1999

Internal carotid artery transposition: another cause of widening of the retropharyngeal space.

We present four cases of internal carotid artery (ICA) transposition which caused widening of the retropharyngeal soft tissues. Internal carotid artery transposition is a rare cause of retropharyngeal space enlargement, which can be accurately diagnosed in a non-invasive manner with spiral CT. Radiologists should be aware of this entity in the differential diagnosis of retropharyngeal space enlargement in symptomatic (dysphagia, pulsatile mass) and asymptomatic patients, and alert the clinician of its existence, due to the risk of massive bleeding if neck surgery is to be performed.

Aged↗
PubMed1999

Prevalence of the angiotensin I converting enzyme insertion/deletion polymorphism, plasma angiotensin converting enzyme activity, and left ventricular mass in a normotensive Chilean population.

The aim of this study was to estimate the prevalence of the different alleles of the angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and associated plasma ACE activity, as well as cardiac echocardiographic structure, in a healthy Chilean population. We selected 117 healthy normotensive subjects (aged 45 to 60 years, middle socioeconomic status, nonobese, and nondiabetic) from a population-based study concerning the prevalence of risk factors for chronic diseases (Conjunto de Acciones Para la Reducción Multifactorial de las Enfermedades no Transmisibles [CARMEN]). The frequencies of the I and D alleles were 0.57 and 0.43, respectively. Mean plasma ACE activity was 15.3 +/- 3.9 U/mL. Compared with subjects with the II genotype, plasma ACE activity was significantly higher in subjects with the ID and DD genotypes with no difference between them. No correlation was observed between blood pressure and plasma ACE activity. Among the three different genotypes there was no difference in left ventricular (LV) dimensions or in LV mass. No correlation between plasma ACE activity and LV mass was observed for either gender or different genotypes. Multivariate linear regression analysis using LV mass and LV mass index as dependent variables showed independent effects (P < .05) for gender (higher LV mass in men) and diastolic blood pressure, but not for the DD genotype. In conclusion, in this population, the presence of the D allele on the ACE gene determined higher circulating ACE activity. However, in this normotensive healthy population, male gender and diastolic blood pressure, but not the presence of the D allele, were associated with increased LV mass.

Alleles↗
PubMed1999

Allergy to the pine processionary caterpillar (Thaumetopoea pityocampa).

BACKGROUND: The contact with the pine processionary caterpillar (Thaumetopoea pityocampa) induces dermatitis and ocular lesions by a mechanic and toxic mechanism. However, IgE-mediated hypersensitivity to this caterpillar has been demonstrated in two recent studies. OBJECTIVE: To find if an IgE-mediated mechanism was operative among patients with suspected previous reactions to processionary caterpillars, particularly exposed workers. METHODS: Fifty-five patients were studied by skin prick test (SPT), and specific IgE detection by immunoblotting. RESULTS: A total of 58.18% patients had a positive SPT for caterpillar extract. Positive SPT patients had more generalized cutaneous reactions (47%) and oedema (50%) as well as a shorter latency period (mean, 36 min) and duration of cutaneous lesions (mean, 26 h) than the patients with negative SPT. A total of 60% of the positive SPT patients had occupational exposure to the processionary caterpillar. The occupationally exposed workers showed significant symptoms from October to December. The anaphylactic reactions only appeared in allergic patients with occupational exposure and were also more frequent from October to December. These patients with anaphylactic reactions had a major size of SPT and the exercise was found in them to be a variable that increased the symptoms. The IgE immunoblot detected in the caterpillar extract several reactive bands with apparent molecular weights from to 35-4 kDa in 72% of the cases with positive SPT. CONCLUSIONS: Allergic reactions to T. pityocampa urticating hairs have different clinical characteristics than those induced by a toxic-irritative mechanism and are more frequent than suspected. Allergic reactions to this caterpillar among occasional visitors to pine-wood areas, and particularly in pine-forest workers, should be taken into consideration by allergists.

Adult↗
PubMed1999

Infusion phlebitis in post-operative patients: when and why.

BACKGROUND: The most common complication of intravenous therapy is infusion phlebitis. This study was done to prospectively assess its frequency in a series of consecutive patients who will undergo surgery, and to identify which variables may predict an increased risk for phlebitis. PATIENTS AND METHODS: 400 consecutive patients who will undergo surgery in a general surgery department were included. Only the first catheter, inserted the day before surgery, was taken into account. Eighteen variables (from the infusion, the catheter and from the patient) were prospectively evaluated for their contribution to the occurrence of phlebitis. RESULTS: 60/400 patients (15%) developed phlebitis, and most of them needed insertion of a further catheter. The univariate analysis showed that patients who developed phlebitis were older, and their pre-operative levels of both blood haemoglobin and neutrophil cound were significantly higher than those in patients who did not develop phlebitis. However, the multivariate analysis only confirmed the association with blood haemoglobin levels: the risk of phlebitis sharply increased in the patients with the highest haemoglobin levels. As to the influence of time on phlebitis development, there was a significant decrease in the day-specific risk, from the 5th day on. COMMENTS: In our series, blood haemoglobin levels were found to be the only variable associated to a higher risk of phlebitis. Besides, in contrast with the recommendations by the Centers for Disease Control, no significant increase in the day-specific risk of phlebitis was found. Thus, a guideline to select the type of catheter to be inserted in an individual patient is suggested.

Adolescent↗
PubMed1999

Functional magnetic resonance imaging and radiosurgical dose planning.

OBJECTIVE: To assess the effect of functional magnetic resonance imaging (fMRI) on stereotactic radiosurgical (SRS) dose planning. METHODS: Patients included those undergoing SRS whose lesions were in or near areas that could be identified with fMRI. After processing, an fMR scan was registered to the anatomic scan, and this dataset was registered to a stereotactic CT scan. The imaged functional areas were contoured along with standard anatomical targets. Dose planning was done at first with the functional volumes rendered invisible; the plans were then adjusted as needed using the functional targets. Doses were measured using a dose-volume histogram tool. RESULTS: SRS was performed in 12 patients, 1 of whom also underwent SRT. Functional volumes studied included motor cortex in 8 patients, visual in 6 and language in 3; a total of 33 functional targets were imaged. Prescription doses ranged from 12 to 22.5 Gy (mean 19.5 Gy), and the maximum dose to functional volumes from 8 cGy to 18.5 Gy (mean 2.9 Gy). In 6 patients, arc adjustment using functional targets yielded a >50% reduction in dose to at least one functional volume; in all patients, the dose reduction to 50 and 75% of functional volumes averaged 4% (12 cGy) and 13% (30 cGy), respectively, while the reduction of maximal dose averaged 24% (50 cGy). CONCLUSIONS: fMRI can be used in SRS to reduce irradiation of eloquent brain using standard prescription doses. Appropriate arc adjustment may allow for escalation of the dose to the targeted lesion.

Adult↗
PubMed1999

[Pericarditis secondary to the rupture of a hydatid cyst].

Cardiac hydatic cysts are rare and represent 0.5 to 2% of all hydatic cysts in humans, but usually associated with fatal complications. We report a case of a male 27 years old with a hydatid cyst located in left ventricle asymptomatic until rupture. It was diagnosed by two-dimensional echocardiogram in a control.

Adult↗
PubMed1999

[Chronic exposure to environmental lead in Chilean infants. II: Effects on the psychomotor development].

BACKGROUND: Lactating children are specially susceptible to lead toxicity due to their underdeveloped nervous system, lower body mass, higher intestinal absorption and lower elimination rates. AIM: To determine the effects of lead exposure, comparing Chilean lactating children residing in rural areas with low lead exposure, and in urban areas with high lead exposure. MATERIAL AND METHODS: Newborns from public maternity hospitals of the rural locality of San Felipe and from Metropolitan Santiago, were recruited for the study. On admission to the study, umbilical cord and maternal blood samples were obtained and an inquiry about perinatal, sociohereditary and lead exposure history was done. Children were followed every 6 months until 24 months of age, measuring blood parameters and neurobehavioral development using Bayley scales. RESULTS: Three hundred twelve children from Santiago and 113 from San Felipe were studied. Maternal and children blood lead levels were higher in Santiago, but lower than those reported in other international studies. At 24 months of age, 4.5% of children from Santiago and 0.7% of children from San Felipe had levels over 10 micrograms/dl. No differences in neurobehavioral development were observed between children of both cities. At 24 months, scores of MDI scales were 91 in Santiago and 97 in San Felipe. The figures for PDI scale were 93 in Santiago and 93 in San Felipe. Main risk factors for a retarded neurobehavioral development were socieconomic level with a mean Odds ratio of 3.5 (0.99-12.4), made sex with an Odds ratio of 2.3 (1.09-5.07) and stimulation at home with an Odds ratio of 0.7 (0.53-0.82). CONCLUSIONS: In this cohort of children, no effect of lead levels on neurobehavioral development was found.

Analysis of Variance↗
PubMed1999

[Immune status against measles and rubella among 4 Chilean groups of different ages].

BACKGROUND: Results of clinical and epidemiological studies confirm that no cases of measles have occurred in Chile since 1993. However, since covering of vaccination programs do not exceed 95%, an immunological surveillance for this disease is warranted. AIM: To know the immune status against measles and rubella in the Chilean population. MATERIAL AND METHODS: A serological census of a representative sample of communities with high (90% or more) or low immunization coverings was performed. Four sub samples along the country were selected: 122 children aged 18 months of age (stratum A), 1,276 children attending the first years of basic school (stratum B), 899 teenagers in their last high school year (stratum C) and 399 women attending a family planning clinic (stratum D). IgG antibodies against measles and rubella were measured using ELISA and hemagglutination inhibition techniques, respectively. RESULTS: Antibodies against measles and rubella were found in 96% and 94% of study subjects. No differences in these titres were found between different strata or communities with high or low vaccination covering. There is a high percentage of positive antibodies against measles among children of 18 months of age and a high percentage of antibodies against rubella among teenagers and women in family planning. Only 3% of the sample had not received any vaccine at the moment of the study. CONCLUSIONS: The high prevalence of antibodies against rubella allows to conclude that it is not necessary to consider this antigen in the next vaccination campaign. Due to the high prevalence of antibodies against measles, only the population older than 20 years old should be affected by the disease if this virus enters the country.

Adolescent↗
PubMed1999

[Prevalence of hypertension in Valparaíso. Results of the base survey of the CARMEN project (Set of measures for the multifactorial reduction of non-transmissible diseases)].

BACKGROUND: There is little information about the real prevalence of hypertension in Chile. AIM: To assess the adjusted prevalence of hypertension and its main therapeutic measures among adults living in Valparaiso, Chile. MATERIALS AND METHODS: A random sample of dwellings in Valparaiso was chosen. Among these, an individual of 25 to 64 years old was randomly surveyed for risk factors for chronic diseases and sociodemographic parameters. Blood pressure, weight, height, oral glucose tolerance test, fasting cholesterol and triglycerides were also measured. Prevalence was pondered according to age, sex, and probability of selection in the dwelling interior. RESULTS: Three thousand one hundred twelve individuals were studied. The adjusted prevalence of hypertension was 11.4% (11.6% among females and 10.6% among men). The prevalence increased along with age from 3 and 1.9% in men and women of 25 to 34 years old respectively, to 18.2 and 27.4% among men and women of 55 to 64 years old (p < 0.01). People of low socioeconomic level had a higher prevalence of hypertension than those of high socioeconomic level (14.2 and 9.3% respectively, P < 0.05). Diabetes, obesity and hypercholesterolemia were significantly more frequent in subjects with hypertension than in the general population. Forty-four percent of diagnosed hypertensives were receiving medications (angiotensin converting enzyme inhibitors 40%, calcium antagonists 34%, beta blockers 22%). Twenty five percent of patients were treated with a combination of medications. Of those treated, only 22% had normal blood pressure levels at the moment of examination. CONCLUSIONS: High blood pressure is an important public health problem that requires more efficient detection and treatment programs.

Adult↗
PubMed1999

[Risk factors for non communicable diseases: methods and global results of the CARMEN program basal survey].

BACKGROUND: In the last decades, chronic non communicable diseases are becoming the main cause of disability and mortality among adults. The risk factor surveillance and management is the most efficient mean of reducing the impact of these diseases. AIM: To report the results of a non communicable disease risk factor surveillance program in Valparaiso, Chile. MATERIAL AND METHODS: A random samples of people aged 25 to 64 years old living in Valparaiso, Chile was studied. Subjects were questioned about smoking and physical activity habits. Blood pressure, height and weight were measured using standardized techniques at their homes and blood samples were obtained to measure serum lipid levels and oral glucose tolerance test at the nearest outpatient clinic. RESULTS: Of the initial 3852 homes selected, 752 individuals did no agree to answer the inquiry, therefore 3120 subjects were finally interviewed. Of these, 40.6% were smokers, 15% drank alcohol in two or more occasions per month, 84.6% were physically inactive, 19.7% had a body mass index over 30 kg/m2, 11.1% had high blood pressure, 3.9% were diabetic and 46.9% had high serum cholesterol levels. CONCLUSIONS: The basal survey for the CARMEN program shows a high prevalence of cardiovascular risk factors among Chileans.

Adult↗
PubMed1998

Decline in sexually transmitted disease prevalence in female Bolivian sex workers: impact of an HIV prevention project.

OBJECTIVE: To implement an HIV prevention intervention among female commercial sex workers (CSW), and to monitor key outcomes using routinely collected clinical and laboratory data. DESIGN: Cross-sectional and longitudinal analysis of data from an open-enrollment cohort. SETTING: One public sexually transmitted disease (STD) clinic and about 25 brothels in La Paz, Bolivia. PARTICIPANTS: A total of 508 female CSW who work at brothels and attend a public STD clinic. INTERVENTION: Improved STD clinical care, supported by periodic laboratory testing, and behavioral interventions performed by a local non-governmental organization. MAIN OUTCOME MEASURES: Prevalence of gonorrhea, syphilis (reactive plasma reagin titer > or = 1 : 16), genital ulcer disease, chlamydial infection, and trichomoniasis; self-reported condom use in the previous month; and HIV seroprevalence. RESULTS: From 1992 through 1995, prevalence of gonorrhea among CSW declined from 25.8 to 9.9% (P < 0.001), syphilis from 14.9 to 8.7% (P = 0.02), and genital ulcer disease from 5.7 to 1.3% (P = 0.006); trends in prevalence of chlamydial infection and trichomoniasis were not significant. Self-reported condom use during vaginal sex in the past month increased from 36.3 to 72.5% (P < 0.001). In a multivariate analysis, condom use was inversely associated with gonorrhea [odds ratio (OR), 0.63; 95% confidence interval (Cl), 0.41-0.97], syphilis (OR, 0.39; 95% Cl, 0.23-0.64), and trichomoniasis (OR, 0.44; 95% Cl, 0.32-0.71). In 1995, HIV seroprevalence among CSW was 0.1%. CONCLUSION: Effective prevention interventions for female CSW can be implemented through public services and non-governmental organizations while HIV rates are still low, and key outcomes can be monitored using data obtained from periodic screening examinations.

Adult↗
PubMed1998

Tobacco mosaic virus disassembly by high hydrostatic pressure in combination with urea and low temperature.

We investigated the effect of low temperature and urea combined with high pressure on tobacco mosaic virus (TMV). The evaluation of its aggregation state and denaturation process was studied using gel filtration, transmission electron microscopy, and spectroscopic methods. The incubation at 2.5 kbar induced 18% dissociation, and decreasing of temperature to -19 degreesC promoted additional dissociation to 72%, with stabilization of the dissociation products. Under such conditions, extensive denaturation did not occur. The apparent enthalpy and entropy of dissociation (Delta and TDelta) were -9.04 kcal/mol subunit and -15.1 kcal/mol subunit, respectively, indicating that the TMV association is an entropicly driven process. The apparent free energy of stabilization given by the presence of RNA is at least -1.7 kcal/mol subunit. Urea-induced dissociation of TMV samples and incubation at high-pressure promoted a higher degree of dissociation. The volume change of dissociation decreased in magnitude from -16.3 to -3.1 mL/mol of dissociated subunit, respectively, in the absence and presence of 2.5 M urea, suggesting exposure of the protein-protein interface to the solvent. High-pressure induced remarkable TMV denaturation in the presence of 2.5 M urea, with a volume change of -101 mL/mol of denatured subunit. The apparent enthalpy and entropy of denaturation (Delta and TDelta) by 1.75 M urea at 2.5 kbar was -11.1 and -10.2 kcal/mol subunit, respectively, demonstrating that the TMV protein coat presents an apparent free energy of denaturation by urea close to zero. Although the processes could not be assumed to be pure equilibria, these thermodynamic parameters could be derived by assuming a steady-state condition.

Atmospheric Pressure↗