Biomedical subjects

R Lucena

Publications and source records attributed to R Lucena.

At least 37 records · Page 2Linked to original sources

PubMed1998

Effects of haemolysis, lipaemia and bilirubinaemia on an enzyme-linked immunosorbent assay for cortisol and free thyroxine in serum samples from dogs.

The possible interference of haemolysis, lipaemia and bilirubinaemia on commercially available enzyme-linked immunosorbent assays (test kits Enzymun-Test; Boehringer Mannheim) for cortisol and free thyroxine (FT4) in canine plasma samples was studied. Serum samples from 20 clinically normal dogs were enriched in vitro with different amounts of fresh haemolysate, lipid and bilirubin and compared with the original sera. The tests were used in connection with the analyser system Enzymum-Test (Boehringer Mannheim) System ES300. Haemolysis significantly (P = 0.039) interfered with the accuracy of FT4 determination independent of haemoglobin concentrations. Thus, haemolysis should be avoided in FT4 testing by competitive enzyme immunoassay. Lipaemia significantly interfered (P = 0.0015) with cortisol determination but not with FT4 determination (P = 0.41). Regression analysis showed that FT4 concentration significantly increased as triglyceride levels increased, especially at concentrations greater than 125 mg dL-1. The positive bias observed was of no diagnostic importance for cortisol results and the increase of FT4 levels could be precisely predicted by linear regression analysis. The addition of bilirubin significantly (P = 0) interfered with cortisol testing but, as with lipaemia, the magnitude of the differences were of no clinical significance.

Animals↗

PubMed1998

Validation of a commercially available enzyme-linked immunosorbent assay (ELISA) for the determination of cortisol in canine plasma samples.

Samples were obtained from clinically normal dogs before and after ACTH stimulation and dexamethasone suppression tests. The test kit Enzymun-Test (Boehringer Mannheim) for determining cortisol concentrations in human plasma was used in connection with the analyser system Enzymun-Test (Boehringer Mannheim) System ES300 following the manufacturer's instructions. The intra-assay and inter-assay coefficients of variation were 1.28% and 5.64%, respectively. The mean recovery when assaying samples with a cortisol content of more than 100 nmol/L was 95.41%, but this percentage decreased in samples with lower cortisol levels. The sensitivity of the assay was 2.76 nmol/L. The results of the ACTH stimulation and dexamethasone suppression tests were similar to those published previously. The ELISA method evaluated allows a precise and sensitive determination of cortisol concentrations in canine plasma samples. The major drawback observed was the loss of accuracy at low cortisol concentrations. Since the assay tends then to report lower cortisol concentrations, the generally accepted concentration of 40 nmol/L may not be suitable as the cutoff value in dexamethasone suppression tests.

Adrenal Cortex Diseases↗

PubMed1998

Levels of IgM and IgA circulating immune complexes in dogs with leishmaniasis.

The concentrations of IgM and IgA circulating immune complexes (CIC) were determined in 82 dogs with naturally acquired leishmania infection and in a control group of 25 healthy dogs. The mean serum IgM and IgA CIC concentration in infected dogs were significantly (IgM; P < 0.004; IgA; P < 0.000) higher than in the control group. An increase in IgM and IgA CIC concentration was found in 47.6 and 95.1%, respectively, of the leishmania-infected dogs. The serum IgM and IgA CIC concentrations in infected dogs showing hypercreatininaemia were not statistically higher than those of sick dogs with normal creatininaemia. When hypercreatininaemia (> or = 1.30 mg/dl) was used as an indicator for CIC disease, the positive predictive value obtained with 0.368 for IgM CIC and 0.894 for IgA CIC, indicating that renal function impairment was associated with the high serum IgM and IgA CIC concentrations in 36.8 and 89.4%, respectively, of the infected dogs.

Animals↗

PubMed1998

Evaluation of a commercial ELISA test for the detection of allergen-specific IgE antibodies in atopic dogs.

A commercial enzyme-linked immunosorbent assay (ELISA) designed to detect allergen-specific immunoglobulin (Ig)E antibodies were evaluated in 36 atopic dogs and in 12 normal dogs. The test showed a sensitivity of 72.23% and a specificity of 41.6%. Positive and negative predictive values were 76.47 and 35.71% respectively. Correlation between the ELISA kit results and intradermal skin testing varied depending on the allergen and ranged from 47.1 to 80.4%, although positive correlation (i.e. allergens positive in both tests) ranged rom 2.7 to 19.4%. In conclusion, this serological test gave both false positive and false negative results. Sensitivity, specificity and predictive values indicate that this ELISA may not be useful in canine atopy. Although correlation studies were hampered by the impossibility of using the same allergenic extracts, the correlation observed between intradermal and serological testing indicates that results from both tests are not interchangeable.

Allergens↗

PubMed1998

Use of allopurinol for maintenance of remission in dogs with leishmaniasis.

Current treatments for infected dogs with leishmaniasis do not always provide long-term control of the disease and clinical relapses are common. In this study, the usefulness of long-term allopurinol administration in the maintenance of clinical remission in canine leishmaniasis was evaluated. Fifteen dogs with natural leishmania infection were subjected to an initial treatment based on the simultaneous administration of meglumine antimoniate (100 mg/kg/day) and allopurinol (30 mg/kg/day). Once clinical remission was achieved, a maintenance treatment with allopurinol (20 mg/kg/day) administered for one week a month was instituted. Results were compared with those of a retrospective control group comprising 15 infected dogs which only followed the induction treatment. Relapses occurred in 86 per cent of control dogs within 14 months of discontinuing treatment. In contrast, those dogs on intermittent oral allopurinol administration were successfully maintained in clinical remission for a follow-up period of 10 to 44 months. In this latter group, specific antibody titres decreased or were unchanged, no side effects directly attributable to allopurinol were seen and treatment was well accepted by the owners. It is concluded that long-term intermittent administration of allopurinol is an effective way of maintaining clinical remission in dogs with leishmaniasis.

Allopurinol↗

PubMed1998

[Survival analysis of acute pyogenic meningitis in children].

In order to determine the survival curves of lethality in acute bacterial meningitis (ABM) in children, we reviewed the charts of all patients admitted to the Hospital Couto Maia from January 1990 to December 1992. The Kaplan-Meir analysis was used to compare the survival rate and hospitalar permanence of patients with identified pathogens with those whose bacteria were not determined. The same analysis was used to compare the curves of the three most frequent agents. Statistical difference between the identified and nonidentified groups was not observed. The analysis of the three curves shows that the first 24 hours were responsible for the most elevated lethality rate. When the curves are compared, it is clear that S. pneumoniae has the most important intrahospitalar lethality and N. meningitidis the most benign evolution. We conclude that efforts have to be made to determine which variables are related to prognosis of ABM at the first day of hospital admission.

Adolescent↗

PubMed1998

[Prognostic factors of tuberculous meningoencephalitis lethality].

In order to describe the lethality predictors of patients with tuberculous meningoencephalitis, records of 231 patients were analysed. Ages ranged from less than 1 year to 68 years. Ninety-seven patients (42%) were four years old or less. Apart from 73.2% of patients whose diagnosis was performed by clinical and epidemiologic criteria associated with response to specific therapy, 26.8% had diagnostic confirmation through cerebrospinal fluid (culture, bacilloscopy, PCR) or necropsy. The lethality predictors were: less than 4 years of age, seizures, and severe alterations of consciousness.

Adolescent↗

PubMed1997

Cutaneous protothecosis in a dog.

A dog was infected systemically with Prototheca wickerhamii but showed only cutaneous protothecosis. The lesions appeared progressively and consisted of non-pruritic scrotal swelling and ulceration, cutaneous nodules, crusty ulcerative lesions over the trunk and serous rhinitis. The diagnosis was based on skin biopsy findings and specific culture. Microscopic examination revealed a diffuse pyogranulomatous dermatitis and numerous protothecal organisms of different sizes within the cytoplasm of phagocytic cells. Treatment with oral ketoconazole for six months resolved all the clinical signs except the scrotal granuloma which, although it was significantly reduced, had to be removed surgically. However, after five months the condition returned.

Animals↗

PubMed1997

Canine cutaneous protothecosis: an immunohistochemical analysis of the inflammatory cellular infiltrate.

In this immunohistochemical study, the distribution of the cellular inflammatory infiltrate associated with cutaneous canine protothecosis (Prototheca wickerhamii) was evaluated by consecutive biopsies taken before, during and after treatment. Antibodies specific to canine immunoglobulins (IgG, IgM, IgA), human CD3 antigen (pan T-lymphocyte marker) and human myeloid/ histiocyte antigen (macrophage/neutrophil marker) were used. Before treatment, cellular infiltrate was very scanty in the inflamed areas, but it increased during the treatment, whereas the number of protothecal organisms decreased. Statistical analysis revealed an inverse relation between the number of protothecal organisms and the number of infiltrating macrophage/neutrophils (P < 0.004), T lymphocytes (P < 0.001), and cells containing immunoglobulin G (P < 0.001), M (P < 0.001) and A (P < 0.001) at different stages of the disease. These findings suggest either that protothecal organisms inhibit the migration or proliferation of cellular inflammatory infiltrate or that only dead protothecal organisms induce an effective local immune response.

Animals↗

PubMed1997

Total protein and immunoglobulin concentrations in equine tears.

Lacrimal fluid represents a major ocular surface defensive mechanism providing different concentrations of all immunoglobulin classes. In this report, four classes of immunoglobulins (IgA, IgM, IgG and IgGT) have been measured in horse tears. As in others species, IgA is the main immunoglobulin responsible for local protection and constitutes quantitatively, 50% of all lacrimal proteins. The rest of immunoglobulins studied are normally present in equine tear fluid (though in lower concentration) and contribute to ocular surface immune protection. Female and adult horses showed significant higher mean IgA concentration than male and young horses. The lack of a significant correlation between plasma and tear immunoglobulin level suggest the presence of active transport or secretion mechanisms similar to that reported for IgA in other species.

Aging↗

PubMed1997

Concentrations of plasma immunoglobulins in the dog as determined by laser nephelometry. Comparison with radial immunodiffusion and enzyme-linked immunosorbent assay.

Concentrations of immunoglobulins were determined by laser nephelometry and, for comparison, by single radial immunodiffusion assay and a sandwich enzyme-linked immunosorbent assay (ELISA) in plasma samples of normal dogs. Correlation between methods was high, although the mean IgM concentrations determined by laser nephelometry were significantly higher than those determined by the single radial immunodiffusion assay or ELISA. In contrast, the mean IgA concentrations were significantly lower than those determined by ELISA. Laser nephelometry was the most reproducible method. The between-assay coefficient of variation was 4.12% for IgG, 6.98% for IgM and 6.35% for IgA. Laser nephelometry and ELISA showed similar accuracies, and both were more accurate than single radial immunodiffusion. Finally, laser nephelometry was much more sensitive than single radial immunodiffusion, but less sensitive than the ELISA method. In conclusion, results of the three methods were in general comparable. The higher range of linearity precision and accuracy of laser nephelometry, and the availability of automated nephelometers make this the method of choice for quantifying canine plasma immunoglobulins.

Animals↗

PubMed1997

[Clinical and laboratory characteristics of pyogenic meningitis in adults].

We reviewed the charts of 176 adult patients, admitted with a diagnosis of acute bacterial meningitis, in the Hospital Couto Maia, from January 1990 to December 1992. All the patients had community-acquired meningitis. In 120 patients we could identify the causative agent on Gram's staining and culture. The most common pathogens were N. meningitidis (56.7%) S. pneumoniae (37.5%) and E. coli (3.3%). The overall lethality rate was 19.8% and the lethality was greater in the group with streptococcus meningitis (31.8%). The mean age and the leukocyte in the peripheral blood were greater in the group with S. pneumoniae meningitis than in the meningococal group. Cutaneous hemorrhagic lesions was and excellent predictor meningococcal meningitis.

Adolescent↗

PubMed1997

[Laboratory and clinical variables in the differential diagnosis of aseptic and pyogenic meningitis in children].

We reviewed the charts of 573 children with a final diagnosis of pyogenic or aseptic meningitis, who were hospitalized in a large reference hospital for the treatment of infectious disease, from January 1990 to December 1992. Seizures, decreased consciousness, nuchal rigidity were more frequent in bacterial than in aseptic meningitis. A cerebrospinal fluid (CSF) glucose level lower than 45 mg/dL, a protein level equal or greater than 140 mg/dL and cell count greater than 600/mm3 were predictors of pyogenic meningitis. Receiver operating characteristic curve analysis was used to assess the best point in CSF measures of leukocytes, glucose and protein that could predict bacterial meningitis. These results suggest that clinicians should differentiate bacterial from aseptic meningitis in children with greater accuracy utilizing only clinical and simple CSF data.

Acute Disease↗

PubMed1996

Antinuclear antibodies in dogs with leishmaniasis.

An indirect immunofluorescence method using rat liver as material was developed to determine the incidence of antinuclear antibodies in serum from 44 adult dogs naturally infected with leishmaniasis and, for comparative purposes, in a control group of 30 healthy dogs. Animals in both groups were of different breeds with a similar age distribution. Antinuclear antibodies were not detected in the healthy dogs and only 15.9% of the diseased dogs, 12.0% males and 21.1% females, were positive. The results indicate that in contrast to previously reported figures, the incidence of antinuclear antibodies is low in canine leishmaniasis at least when diagnosis is first made. In order to investigate whether antinuclear antibodies may play a role in the development of the renal damage observed in canine leishmaniasis, the concentrations of serum creatinine were related to the presence of antinuclear antibodies. Only 28.5% of the antinuclear antibodies positive infected dogs showed hypercreatininemia as did 32.4% of the antinuclear antibodies negative infected dogs. Thus, antinuclear antibodies are not significantly cause-effect related to the development of the renal lesions seen in canine leishmaniasis.

Animals↗

PubMed1996

Circulating immune complexes and renal function in canine leishmaniasis.

A third component of complement (C3) capture enzyme-linked immunosorbent assay was used to determine the concentration of IgG circulating immune complexes (CIC) in 91 dogs with naturally acquired leishmania infection and in a control group of 24 healthy dogs. Results were expressed as a percentage of a reference standard. Mean concentrations of CIC were significantly (P < 0.001) higher in leishmania-infected dogs (228.725 +/- 14.283%) than in controls (74.542 +/- 12.614%). An increase in CIC concentration was found in 57.1% of the leishmania-infected dogs. No significant differences could be recorded in CIC levels between males and females in either group. Infected dogs showing hypercreatininemia rendered a statistically significant (P < 0.030) higher serum CIC concentration than sick dogs with normal creatininemia. When hypercreatininemia (> or = 1.30 mg/dl) was used as an indicator for CIC increase, the positive predictive value obtained was 0.9 indicating that renal function impairment was associated with high serum CIC concentration in 90% of the infected dogs.

Animals↗

PubMed1996

Prognosis of bacterial meningitis in children.

We studied the incidence and prognosis of acute neurologic complications in 281 children under 13 years of age with a diagnosis of acute bacterial meningitis. All the patients were examined daily by the same group of neurologists, using a standardized neurological examination. Patients with signs of encephalic lesions, unsatisfactory response to antibiotics or decreased level of consciousness were submitted to brain computer tomography. The overall lethality rate was 20.3% and cases whose causative agent was identified presented a higher lethality rate (23.7%) than those in which the agent was not found. The most important neurological abnormalities were meningeal signs (88.3%) followed by decreased consciousness (47.7%), irritability (35.2%), seizures (22.4%), fontanel bulging (20.6%) and cranial nerve palsy (14.2%). Seizures, cranial nerve palsy and the absence of meningeal signs were related to higher rates of lethality. Diminished consciousness, seizures, subdural effusion, abscess and hydrocephalus were the most important complications, respectively. We can conclude that acute bacterial meningitis continues to be an important health problem in developing countries and that public health measures will be necessary to minimize the impact of sequelae and reduce the mortality rate in children with that pathology.

Child↗

PubMed1996

[Clinical and laboratory characteristics of bacterial meningitis in children].

Data from the records of 528 children under 15 years old with diagnosis of acute bacterial meningitis, admitted at the Hospital Couto Maia between 1990 and 1992 were analyzed. Bacterial meningitis was more frequent in children under the age of 1 year (37.8%). The most common etiologic agent was H. influenzae (42.2%). The global lethality was 20.9%. Individual predictors of poor outcome were: absence of the "classic triad", CSF cell count under 1000/mm3, age under 2 years, presence of seizures, depressed sensorium, and S. pneumoniae as causal agent.

Adolescent↗

PubMed1995

Skin-prick tests for hypersensitivity to alpha-amylase preparations.

Twenty-five asthmatic subjects with suspected alpha-amylase hypersensitivity were studied by skin-prick tests, a capture ELISA, immunoblotting and bronchial provocation tests. At the same time, different amylases were analysed by SDS-PAGE and immunoblotting using a polyclonal rabbit antiserum. Eight patients showed a positive bronchial response to amylase. Seven of them had positive skin-prick tests, with this method being the most sensitive approach for diagnosis. However, in four cases, skin tests were also positive although the patients had a negative provocation test, thus demonstrating that skin tests are not specific. ELISA and blotting showed similar results in terms of sensitivity and specificity. The enzymes used by the workers included several antigens besides alpha-amylase. The rabbit antiserum to alpha-amylase detected a protein in a wheat flour extract. In one case, the IgE antibodies were specific only for a contaminant of lower molecular weight than amylase. These facts suggest that proteins from the culture medium could be responsible for some cases of amylase hypersensitivity, making the diagnosis difficult. The presence of amylase in another enzymatic extract, a protease produced by Aspergillus oryzae, was proved by means of skin tests and immunoblotting, thus demonstrating the allergenic properties of this enzymatic preparation.

Asthma↗