PubMed Health⌕ Search

Biomedical subjects

A Téllez

Publications and source records attributed to A Téllez.

At least 19 recordsLinked to original sources
PubMed2005

Secretory antibodies against Giardia intestinalis in lactating Nicaraguan women.

Secretory IgA (sIgA) antibodies are important in the host defence against the intestinal protozoan parasite Giardia intestinalis. However, few antigens have been identified. In this study 100 milk and saliva samples from lactating women, living in an endemic region (León, Nicaragua), were screened for the presence of antibodies against G. intestinalis. Most milk and saliva samples contained anti-Giardia antibodies (59% and 52%, respectively), with a mean sIgA content 50 times higher in milk than in saliva. The positive samples reacted with trophozoite membrane, flagella and cytoplasmic antigens. Western blot analysis showed that milk and saliva anti-Giardia sIgA recognized up to 16 different Giardia proteins in the molecular weight region 20-165 kDa. Two-dimensional Western blotting showed that the major immunoreactive proteins were the same as the immunoreactive proteins identified by serum from acute giardiasis patients in a non-endemic country. The major difference was a stronger reactivity against the variant surface proteins (VSPs) in the milk samples. Milk sIgAs also recognized recombinant Giardia proteins such as alpha-1 giardin, ornithine carbamoyl transferase, VSP-4EX, arginine deaminase and alpha-enolase. These antigens will be important targets in the development of new immunodiagnostic tools and vaccines.

Animals↗
PubMed2004

Tannic acid interferes with the commonly used laccase-detection assay based on ABTS as the substrate.

Laccase enzymatic activity in biological samples is usually detected spectrophotometrically through its capacity to oxidize several specific aromatic compounds. One of the most commonly used substrates is the compound 2-2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), which becomes green-blue coloured when it is oxidized by laccase. In this work we study the interference of tannic acid with the spectrophotometric assay to detect laccase by using ABTS as the substrate. Our data show that under the normal reaction conditions of this assay, but in the absence of any catalyst, tannic acid is able to carry out the chemical reduction of the oxidized specie of ABTS, thus decreasing the overall detectable laccase-activity values observed when this enzyme is present in the reaction mixture. Therefore, our results represent an important warning concerning a commonly used method for measuring, detecting or screening laccases in biological samples that may content tannic acid or structural-related molecules.

Benzothiazoles↗
PubMed2004

Evaluation of an automated complement-fixation test (Seramat) for diagnosis of acute respiratory infections caused by viruses and atypical bacteria.

The complement-fixation test (CFT) permits low-cost screening of serum samples for different agents within a single assay, and is a useful tool for the serological diagnosis of acute respiratory infections. This study evaluated the automated Seramat CFT system with 160 paired serum samples taken from 80 patients with acute respiratory infection in comparison with in-house CFTs against a panel of agents, including influenza A and B, adenovirus, respiratory syncitial virus, cytomegalovirus, Mycoplasma pneumoniae, Coxiella burnetti and Chlamydia spp., and in comparison with indirect immunofluorescence (IIF) against Legionella pneumophila. Overall, the Seramat system identified 75 (88.2%) of the 85 seroconversions recognised by in-house CFTs or IIF. In comparison to the in-house CFTs, the correlation was 89.2% (66/74). For L. pneumophila, the Seramat system detected nine (81.8%) of the 11 cases diagnosed by IIF. The Seramat system also identified eight additional seroconversions that were not detected by the in-house assays; none of these seroconversions was detected by the in-house assay on retesting. The Seramat system represents a significant technical improvement that may enable many clinical laboratories to use the CFT as a routine diagnostic tool.

Acute Disease↗
PubMed2001

Specific detection of Entamoeba histolytica DNA by hemolysin gene targeted PCR.

Diagnostic differentiation of pathogenic Entamoeba histolytica from non-pathogenic Entamoeba dispar is of great clinical importance. We have developed and evaluated a new polymerase chain reaction (PCR) assay (haemo-PCR) based on the novel E. histolytica hemolysin gene HLY6. The specificity of this assay was confirmed by analyzing different Entamoeba species, faeces samples, human and bacterial DNA, and digestion of amplification products with appropriate restriction enzymes. The sensitivity was confirmed by serial dilutions of E. histolytica HM-1:IMSS DNA in the excess of human DNA. Totally, 45 clinical samples were analyzed by the haemo-PCR assay including amoebic liver abscess (ALA) fluids from 23 patients suspected for amoebiasis, four faeces samples containing E. histolytica and E. dispar, and positive and negative controls. The results were compared with those obtained with PCRs for cystein-rich surface protein (P30) and small subunit ribosomal RNA (ssu rRNA) genes. The haemo-PCR gave a positive result in 18 (89%) ALA fluids compared with 14 (77%) and five (28%) by PCR for p30, and ssu rRNA, respectively. PCR products were obtained only from specimens containing E. histolytica DNA. The haemo-PCR assay was therefore found to be a valuable diagnostic tool for identification of E. histolytica infections both in faeces and ALA samples.

Animals↗
PubMed2000

Distribution of immunoglobulin G (IgG) and A (IgA) subclasses following Q fever vaccination with soluble phase I Coxiella burnetii extract.

High levels of IgG1, IgG3 and IgA2 antibodies have been observed in patients with Q fever following Coxiella burnetii infection. This IgG subclass distribution is more typical of viral and autoimmune diseases than of bacterial infections. It seemed, therefore, of interest to carry out a prospective study of the distribution of immunoglobulin subclasses after vaccination with phase I C. burnetii tricloroacetic soluble extracts to detect possible differences with respect to natural infection. The antibody response found in vaccinees was mainly restricted to the IgG1, IgG2 and IgA1 subclasses. These findings confirm differences in isotype distribution when compared to those of patients with acute or chronic Coxiella infections and opens an area of interest with respect to the role of IgA subclasses.

Adult↗
PubMed2000

Detection of specific IgM antibody in the investigation of an outbreak of pneumonia due to Legionella pneumophila serogroup 1.

OBJECTIVE: Management of outbreaks of pneumonia due to Legionella pneumophila serogroup 1 (SG1) infection requires rapid and accurate diagnostic tests. Current serologic approaches, based on detection of seroconversion for total antibody, do not fulfil this requirement. METHODS: A diagnostic test based on detection of IgM antibody to L. pneumophila SG1 by indirect immunofluorescence was developed and used to evaluate serum samples from patients involved in a community outbreak of L. pneumophila SG1 pneumonia that occurred in Spain. RESULTS: Testing of samples from serologically proven, sporadic cases of pneumonia due to L. pneumophila SG1 (14), cases of atypical pneumonia due to other infectious agents (16) and healthy controls (100) supported the sensitivity and specificity of the assay. On samples from the outbreak, the IgM assay recognized five of six cases with isolation of L. pneumophila SG1 from respiratory secretions or lung tissue and more than 70% of cases with confirmed or presumptive diagnosis as determined by the current serologic criteria. In addition, the IgM assay was positive in 23-70% of patients who fulfilled the clinical and epidemiologic criteria of case definition but did not display diagnostically significant serologic results or who lacked a detectable antibody response in the routine assay. Among cases confirmed by the current criteria, detection of specific IgM was occasionally achieved before the conventional serology gave significant results. CONCLUSION: Incorporation of IgM antibody detection in the current diagnostic criteria for L. pneumophila SG1 infection may help to improve the management of outbreaks of pneumonia due to this agent.

Antibodies, Bacterial↗
PubMed2000

[Coxiella burnetii endocarditis: long-term clinical course in 20 patients].

INTRODUCTION AND OBJECTIVES: Coxiella burnetii is a causative agent of increasingly frequent subacute infective endocarditis, and is associated with elevated morbimortality. Our aim in the present study was to assess the clinical, serological and therapeutic long-term evolution of 20 patients with Coxiella burnetii endocarditis. METHODS: Twenty patients (13 male and 7 female, age 42 +/- 10 years) admitted between 1982 and 1996 were retrospectively studied. All of them fulfilled the Duke criteria modified by Raoult for Q fever endocarditis. RESULTS: Endocarditis involved prosthetic and native valves in 14 and 6 patients, respectively. All patients except one received antibiotic treatment. Patients treated with doxycycline in monotherapy showed worse evolution than those treated with doxycycline in combination with other antibiotics. Valve replacement was performed in 15 patients, due to prosthetic dysfunction in most of them. The overall mortality was 40% (8 patients). At follow-up of 74 months (range 19-156) (mean 74 +/- 47) all patients showed persistent high levels of phase I antibodies. At follow-up of 15 to 65 months (32 +/- 30) antibiotic treatment was suspended in five patients because they were asymptomatic and without microbiologic findings of valvular endocarditis. CONCLUSIONS: Q fever endocarditis was associated with severe complications, which often required valve replacement. All patients showed persistent high serological titers of Coxiella burnetii endocarditis without other signs of active infection. This finding raises the issue of suspending antibiotic treatment in patients with negative microbiologic findings and questions the persistence of abnormal serology as a monitor of treatment efficacy.

Adult↗
PubMed1998

Distribution of IgA subclass response to Coxiella burnetii in patients with acute and chronic Q fever.

The progression of Coxiella burnetii infection to acute or chronic Q fever has been attributed to biological characteristics of the bacterium and to the host immune response. We measured whether serum levels of total and specific subclasses IgA1 and IgA2 could be correlated with the course of disease in acute and chronic Q fever infections, and with the occurrence of endocarditis. In patients with chronic infection, total IgA2 levels were significantly increased. Q-fever-specific IgA1 antibodies were detectable in both acute and chronic infections, but only patients with endocarditis had IgA2 antibodies to C. burnetii phase II antigens. These findings indicate that the measurement of IgA subclasses may be a useful aid in the serological diagnosis of Q fever. Our results reinforce the idea that immunologically mediated host factors are important in the pathogenesis of Q fever and in the disease outcome of this infection.

Acute Disease↗
PubMed1998

Q fever in pregnancy: case report after a 2-year follow-up.

We report an acute Q fever case, a febrile syndrome, in the 14th week of pregnancy. Placental infection was documented by Coxiella burnetii culture. Newborn infection was ruled out on the basis of the absence of serological evidence after 2 years and on clinical normality. Serological diagnosis is reviewed here, as maternal serology was suggestive of chronic Q fever. The clinical progress, following extended observation, was consistent with acute infection. A QpDV plasmid, already described as being common to acute and chronic European cases, was detected.

Adult↗
PubMed1997

Prevalence of intestinal parasites in the human population of León, Nicaragua.

Intestinal parasites appear to be prevalent in Nicaragua, which motivated a more extensive prevalence study in which socioeconomic conditions such as degree of crowding, quality of water supply, type of floor and disposal of excretion, were considered. The study was performed on 1267 stool samples from about 8% of the citizens of the city of León. The overall prevalence of intestinal pathogenic parasites among the 1267 individuals was found to be 47.2%. The prevalence of Entamoeba histolytica/dispar was 18.6% followed by Giardia (15.9%) and Ascaris (13.4%). Other helminths such as hookworms and Strongyloides sp. were found at very low rates. Giardia, in contrast to worm infections, was prevalent already in children under 5 years of age. E. histolytica/dispar increased with age and remained high. Of 595 individuals with intestinal parasites 81% were living in 'poor' conditions and in 13 clusters of households, a lower prevalence of parasites was seen in households characterised as having good socioeconomic conditions. However, several variables appear to be important in determining the prevalence of the individual intestinal protozoa and helminths encountered.

Animals↗
PubMed1995

Lyssavirus in Eptesicus serotinus (Chiroptera: Vespertilionidae).

To determine the prevalence of European Bat Lyssavirus 1 (EBL1), antibodies plasma samples were obtained from 175 serotine bats (Eptesicus serotinus) from four colonies in southern Spain between September of 1991 and September 1992. Five bats were detected with EBL1 virus in one colony in 1989. The prevalence of antibodies rose to 74% in one of the colonies studied (Villarrasa) in the spring of 1992. After a few months the prevalence declined to under 10%. Individuals with a high antibody level in the spring (up to ED50 = 280) had very low titers or no antibodies in the following summer and autumn.

Age Factors↗
PubMed1993

[Autoimmune thyroid pathology of pregnancy and puerperium. Prevalence in a zone of endemic goiter and its impact on the newborn].

The aim of this work was to study the prevalence of thyroid disease in pregnant and puerperal women and newborns in Pirque (Chile) and its possible relation to iodine intake or autoimmune disease. Two hundred twenty eight women with 13.4 +/- 3.4 weeks of pregnancy were examined initially and in 223, laboratory tests were performed. Goiter was found in 107 women. Although all women were euthyroid, those with goiter had higher serum levels of T3 and T4. Nineteen women had positive anti-thyroid antibodies and urinary iodine excretion was > 100 micrograms/g creatinine in 87.2%. Within 2 and 57 weeks after delivery (mean 13.5 weeks), 183 women were reexamined and in 175 laboratory tests were performed. Serum T3 continued to be higher in those with goiter. Fifteen women with positive anti-thyroid antibodies during pregnancy continued to have positive titres; of these, two had a post partum thyroiditis and one a graves disease. Two hundred three newborns were examined and no one had goiter or elevated TSH. It is concluded that there is a high frequency of goiter among pregnant and puerperal women from Pirque, that iodine intake is normal and that there is a low frequency of post partum thyroiditis.

Adolescent↗
PubMed1990

Subclass distribution of the serum and intrathecal IgG antibody response in varicella-zoster virus infections.

The subclass distribution of the varicella-zoster virus (VZV)-specific IgG antibody response was studied in serum samples from 22 patients with primary varicella and 34 with recurrent VZV infections and in cerebrospinal fluid (CSF) samples from 22 patients with recurrent infection who presented with symptoms of aseptic meningitis. IgG1 and 3 were the dominant subclasses among patients with primary and recurrent infections; IgG1 was also prevalent in the CSF samples. The VZV IgG subclass distribution patterns did not allow differentiation between primary and recurrent infections. However, seroconversions for IgG2, 3, or 4 were observed among patients with recurrences who were negative for specific IgM, suggesting that qualitative tests for serum IgG subclass antibody could be helpful for diagnosis in such cases. Herpes simplex virus-specific IgG was found in CSF samples from several patients with meningitis. The results suggest that calculation of the antibody to albumin index is better than IgG subclass antibody assays for discriminating the causative agent in these cases.

Antibodies, Viral↗
PubMed1990

[Meningitis of viral or possible viral etiology in adults: study of 325 cases].

During five consecutive years, 325 patients older than 14 years with acute possibly viral acute meningitis (VAM) were evaluated. Demographical, clinical and laboratory data were obtained. In 50.5% of cases the etiological investigation of the disease was undertaken with different methods. From the diagnostic point of view, the findings can be nonspecific or equivocal, and only the judicious assessment of clinical, laboratory (blood CRP) and the overall CSF measurements can prevent errors in an early phase. The viral studies demonstrated a specific etiology in 46% of the instances where they were carried out. The viruses accounting for VAM which were more commonly identified included varicella-zoster, enteroviruses, parotiditis and herpes simplex.

Acute Disease↗
PubMed1989

Definition of high-proficiency serological markers for diagnosis of varicella-zoster virus infections by enzyme immunoassay.

The levels of Varicella-zoster virus (VZV)-specific IgG, IgM, and IgA antibodies produced in 22 cases of varicella, 22 cases of cutaneous zoster, and 12 cases of acute aseptic meningitis due to VZV in the absence of cutaneous lesions, were measured by indirect enzyme immunoassay (EIA) and compared with those observed in a group of 34 age-matched controls. The definition of cutoff titres for each serological marker and combinations of them allowed early diagnosis of infection in 82% of varicella patients and 91% of patients with acute aseptic meningitis lacking cutaneous lesions on a single serum sample, the specificity being over 90%. The system was as sensitive as the demonstration of intrathecally produced IgG antibodies for the early diagnosis of the infection in 22 cases of neurological disease due to VZV. A working protocol for the serological diagnosis of VZV infections, using currently available EIA reagents, is described.

Adolescent↗
PubMed1989

[Lymphocytic meningitis. Virologic study. Analysis of the study carried out from 1984 to 1986 (632 cases)].

The experience with the virological diagnosis of lymphocytic meningitis in the Centro Nacional de Microbiología during 3 years (1984-1986) included 632 cases. The most common causative organism was the parotiditis virus (46.9%), particularly in children (64.6%), followed by the non-polio enteroviruses (25.3%). The varicella-zoster virus was the most common organism found in adults (33.3%). We describe some clinical and epidemiological aspects, emphasizing the absence of clinical features suggesting herpesvirus infection in about 50% of cases. Finally, we indicate the study techniques or methods more adequate in each instance (specific IgM detection, isolation techniques or detection of intrathecal antibody production), and we define a study protocol for cases of acute lymphocytic meningitis which permits a high diagnostic yield (44.1-54.9%).

Acute Disease↗
PubMed1987

Aseptic meningitis due to varicella-zoster virus: serum antibody levels and local synthesis of specific IgG, IgM, and IgA.

We used an indirect enzyme immunoassay to describe the evolution of serum levels and the intrathecal production of IgG, IgA, and IgM antibodies to varicella-zoster virus (VZV) in eight patients with a syndrome of acute aseptic meningitis (AAM) and evidence of intrathecal production of VZV-specific IgG antibodies. Four of the eight patients showed no cutaneous zoster while hospitalized. Our results suggested an etiologic relation between VZV and AAM in all cases. Furthermore, we observed some differences in the pattern of evolution of antibodies in serum and cerebrospinal fluid in relation to the presence or absence of cutaneous lesions in our patients. These differences could reflect different pathogenic mechanisms in the spread of VZV to the central nervous system and in the production of the AAM syndrome.

Acute Disease↗