Real-time ventilation and perfusion distributions by electrical impedance tomography during one-lung ventilation with capnothorax.

BACKGROUND: Carbon dioxide insufflation into the pleural cavity, capnothorax, with one-lung ventilation (OLV) may entail respiratory and hemodynamic impairments. We investigated the online physiological effects of OLV/capnothorax by electrical impedance tomography (EIT) in a porcine model mimicking the clinical setting. METHODS: Five anesthetized, muscle-relaxed piglets were subjected to first right and then left capnothorax with an intra-pleural pressure of 19 cm H2 O. The contra-lateral lung was mechanically ventilated with a double-lumen tube at positive end-expiratory pressure 5 and subsequently 10 cm H2 O. Regional lung perfusion and ventilation were assessed by EIT. Hemodynamics, cerebral tissue oxygenation and lung gas exchange were also measured. RESULTS: During right-sided capnothorax, mixed venous oxygen saturation (P = 0.018), as well as a tissue oxygenation index (P = 0.038) decreased. There was also an increase in central venous pressure (P = 0.006), and a decrease in mean arterial pressure (P = 0.045) and cardiac output (P = 0.017). During the left-sided capnothorax, the hemodynamic impairment was less than during the right side. EIT revealed that during the first period of OLV/capnothorax, no or very minor ventilation on the right side could be seen (3 ± 3% vs. 97 ± 3%, right vs. left, P = 0.007), perfusion decreased in the non-ventilated and increased in the ventilated lung (18 ± 2% vs. 82 ± 2%, right vs. left, P = 0.03). During the second OLV/capnothorax period, a similar distribution of perfusion was seen in the animals with successful separation (84 ± 4% vs. 16 ± 4%, right vs. left). CONCLUSION: EIT detected in real-time dynamic changes in pulmonary ventilation and perfusion distributions. OLV to the left lung with right-sided capnothorax caused a decrease in cardiac output, arterial oxygenation and mixed venous saturation.

Macroscopic agglutination test for rapid diagnosis of human leptospirosis.

A commercially available slide agglutination test (SAT) for the diagnosis of human leptospirosis was evaluated by comparing it to an immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) and to the microscopic agglutination test (MAT). For all 108 patients, leptospirosis was diagnosed on the basis of a fourfold or greater increase in titer by MAT (seroconversion), and all but 1 of 245 controls were MAT negative (titers, <1:100). Both SAT and the IgM ELISA failed to detect one case of infection (sensitivity, 99%). Only 3 of 145 blood donors and none of the 100 patients with other illnesses were SAT positive (specificity, 99%). The overall results were similar for the three tests; however, SAT and ELISA were statistically more sensitive as initial screening tests. For 22% of the patients, the diagnosis of leptospirosis was made earlier by SAT than by MAT. SAT detected 27 (44%) of 62 MAT-negative patients with the first serum sample. ELISA and SAT had very similar results. Follow-up of patients for 1 year after the onset of symptoms showed a decreasing rate of positivity by SAT from the third month on. The rate of positivity by ELISA decreased more slowly, to about 67% by the end of the study. By MAT all patients were persistently reactive. SAT and ELISA seem to be convenient methods for the rapid and early screening for leptospirosis and could replace the less sensitive MAT. ELISA gives less subjective results than SAT and provides information on IgM kinetics, but it can be performed only by the more sophisticated laboratories. SAT is inexpensive, can be performed more quickly and more easily than ELISA, and could be used by the less well equipped laboratories.

Use of doxycycline for leptospirosis after high-risk exposure in São Paulo, Brazil.

A clinical trial pilot study, double-blinded, randomized, and controlled with a placebo to assess the effectiveness of oral doxycycline (200 mg, single dose) in preventing leptospirosis after high exposure to potentially contaminated water was performed in São Paulo, SP, Brazil. Confirmed cases were defined as those with leptospira IgM antibody and symptoms; asymptomatic cases were those presenting with IgM antibodies but no symptoms; and suspected cases were individuals with symptoms but no IgM antibody. Forty subjects were given doxycycline and 42 were given placebo. In the drug-treated group there were 2 confirmed cases, 11 asymptomatic cases, and 6 suspected cases. In the placebo group there were 5 confirmed, 6 symptomatic, and 5 suspected cases. Even though we found a protective association of doxycycline for confirmed leptospirosis cases (RR = 2.3) and seroconversion only (RR = 2.0), the association was not statistically significant because of the small number of individuals enrolled in this pilot study. We observed that the 22% of the volunteers already had IgM antibodies to leptospirosis at the first sampling. Finally, the attack rate to confirmed, asymptomatic, and suspected cases of Leptospirosis was 8.5%, 22%, and 13%, respectively, in this population.

Detection of Leptospira DNA in patients with aseptic meningitis by PCR.

Samples of cerebrospinal fluid from 103 patients with aseptic meningitis were tested by PCR for detection of leptospires, and the results were compared with those of the microscopic agglutination test (MAT) and an enzyme-linked immunosorbent assay for detection of immunoglobulin M (ELISA-IgM). Of these samples, 39.80% were positive by PCR and 8.74 and 3.88% were positive by MAT and ELISA-IgM, respectively.

Seroprevalence of Trypanosoma cruzi infection in students at the seven-fourteen age range, Londrina, PR, Brazil, in 1995.

Seropositivity for Chagas disease was evaluated in 834 children aged between 7 and 14 from the Municipal Teaching System in the district of Londrina, State of Paraná. A seroprevalence rate of 0.1% was found through the use of an indirect immunofluorescent test and an enzyme-linked immunosorbent assay. This low rate of seroprevalence provides evidence that the vectorial transmission of Chagas disease has been eliminated in Londrina. The main reason for the elimination of vectorial transmission of Trypanosoma cruzi infection, as evaluated by serological tests, may be a remarkable change in the economic structure of the northern region of Paraná in the 1960's. At that time coffee production was almost completely replaced by soy beans, wheat and grazing in the rural areas. This change deeply affected the rural ecology and caused an exodus of the population from rural to urban areas as well as a decrease in the total number of the population of that region. The measures introduced for controlling the disease through the Program of Chagas Disease Control established by the Fundação Nacional de Saúde of the Brazilian Ministry of Health, certainly, had a positive impact on the reduction of American trypanosomiasis prevalence in the area under study. However, it does not seem that this was the most relevant factor responsible for the elimination of vectorial transmission of Chagas disease in Londrina.

A comparative study on IgG-ELISA, IgM-IFT and Kato-Katz methods for epidemiological purposes in a low endemic area for schistosomiasis.

The high sensitivity and the possibility of automation of the enzyme-linked-immunosorbent-assay (ELISA) has indicated this technique as one of the most useful serological test for epidemiological studies. In the present study, an ELISA for detection of IgG antibodies against adult worm antigens (IgG-ELISA) was investigated for epidemiological purposes, in a rural area of the municipality of Itariri (São Paulo, Brazil). Blood on filter paper (1,180 samples) from about 650 schoolchildren were submitted to ELISA and the data compared to the results of the parasitological method of Kato-Katz and also to the IgM-IFT (immunofluorescence test for IgM antibodies to gut associated antigens). The prevalence rates respectively of 8.5%, 43.0% and 56.2% by the Kato-Katz, IgG-ELISA, and IgM-IFT methods suggest the poor sensitivity of the parasitological method for detection of Schistosoma mansoni eggs in individuals with low worm burden, situation commonly observed in low endemic areas. These results can partially explain the poor degree of agreement between the IgG-ELISA and the Kato-Katz, as suggested by the Kappa index of 0.170. Otherwise, the Kappa index of 0.675 showed substantial agreement between the two serological tests. Some discrepancy of results between the two serological techniques must be better investigated.

Immunodiagnosis of human leptospirosis by dot-ELISA for the detection of IgM, IgG, and IgA antibodies.

A dot-ELISA was evaluated using antigen obtained from Leptospira interrogans cultures of the serovars brasiliensis, canicola, cynopteri, hebdomadis, and icterohaemorrhagiae for the detection of human IgM, IgG, and IgA. Single serum samples from 63 patients with the icterohemorrhagic form of leptospirosis in the acute phase, collected 3-14 days (mean = 7 days) after the onset of symptoms were tested. Ten patients were examined during convalescence and followed up for a period of 4-12 months. For a control group, serum samples from 10 apparently healthy individuals with no clinical or epidemiologic history of leptospirosis, and from 38 patients with nonleptospiral illnesses were used. In the acute phase, IgM antibodies were detected in 62 (98%) of 63 patients and IgG and IgA were observed in 70% and 76% of them, respectively. For the admission serum samples, the predictive value negative of the dot-ELISA was 98% for IgM, 72% for IgG, and 76% for IgA detection. All 10 patients followed-up during convalescence showed IgM antibodies up to the sixth month, decreasing to 57% by the 10th month, and persisting in only one of six patients during the 11th and 12th months of follow-up. Immunoglobulin G was detected in six patients up to the fourth month and in two of six individuals up to the end of follow-up. Immunoglobulin A was observed in all patients up to the end of the first month, decreasing progressively up to the sixth month, and was no longer detected in any patients from seventh to the 12th months of follow-up. The dot-ELISA can be used as an important laboratory screening test, especially when detecting IgM antibodies. It proved to be effective in the diagnosis of human leptospirosis, and appears to have advantages in terms of yield, time, and case of execution and low cost.

Dot-ELISA for the detection of anti-Cysticercus cellulosae antibodies in cerebrospinal fluid using a new solid phase (resin-treated polyester fabric) and Cysticercus longicollis antigens.

A dot-ELISA was developed for the detection of antibodies in CSF in the immunologic diagnosis of human neurocysticercosis, using antigen extracts of the membrane and scolex of Cysticercus cellulosae (M+S-Cc) and, alternately, membrane (M) and vesicular fluid (VF) of Cysticercus longicollis (Cl) covalently bound to a new solid phase consisting of polyester fabric treated with N-methylol-acrylamide resin (dot-RT). The test was performed at room temperature, with reduced incubation times and with no need for special care in the manipulation of the support. The sensitivity rates obtained were 95.1% for antigen Cc and 97.6% for antigen Cl. Specificity was 90.6% when Cc was used, and 96.9% and 100% when M-Cl and VF-Cl were used, respectively. No significant differences in titer were observed between tests carried out with homologous and heterologous antigens. The low cost and easy execution of the dot-RT test using antigen extracts of Cysticercus longicollis indicate the test for use in the immunodiagnosis of human neurocysticercosis.

Application of anti-leptospira ELISA-IgM for the etiologic elucidation of meningitis.

Leptospirosis is one of the causes of meningitis, although its importance is not well known. In the present study we contributed to this knowledge by demonstrating specific IgM class anti-leptospira antibodies by the immunoenzymatic method ELISA in 14.6% of cerebrospinal fluid (CSF) samples from 171 patients with meningitis considered to be of indeterminate etiology. The frequencies of positivity were similar in cases with predominance of polymorphonuclear or lymphomonuclear leucocytes in the CSF. Age distribution showed a predominance of the 5 to 15 year age range (72%), and sex distribution showed a predominance of males (68%). The authors discuss the contribution of this method to the etiologic elucidation of meningitis.

[Serodiagnosis of Chagas disease: new reagent for the indirect hemagglutination test (THAI(IAL))]. / Sorodiagnóstico da Doença de Chagas: novo reagente para o teste de hemaglutinação indireta (THAIIAL).

A new reagent was designed to the indirect hemagglutination test (IHATIAL), utilizing goose red blood cells as inert matrix and standardized for the field diagnosis of American trypanosomiasis. The objective was to substitute the lyophilized or frozen reagent of IHAT produced routinely using human erythrocytes in the Adolfo Lutz Institute (São Paulo/Brazil). The standardized reagent presented a long stability in liquid suspension, and was evaluated in 137 serum samples from patient with and without Chagas' disease, by IHATIAL. The diagnostic performance of this test was similar to the IHAT utilizing human erythrocytes and to that of a commercial IHAT kit. The sensitivity was 1.00, specificity 0.98, predictive value of positive 0.96 and of negative 1.00. Different batches of reagent successively produced proved to be reproducible in a quality control method. The new reagent is more economic than the former reagent, it can be produced easily and may be applicable to the seroepidemiologic studies.

Behaviour of specific IgM, IgG and IgA class antibodies in human leptospirosis during the acute phase of the disease and during convalescence.

The behaviour of specific IgM, IgG and IgA class antibodies in human leptospirosis was studied by ELISA. Two groups of patients were followed up, 57 of them in the acute phase and 10 during convalescence, the latter with a mean follow-up of 10.5 months. IgM class antibodies were detected starting on the 2nd day of symptoms and were observed in 100% of patients up to the 5th month, in 66.7% up to the 7th month and in 50% up to the 12th month after the onset of symptoms. IgG class antibodies were first detected on the 7th day of symptoms in 9.1% of patients, with maximum reactivity (87.5%) between the 2nd and 3rd month, and were not detected at all in one patient. IgA class antibodies were detected starting on the 5th day of symptoms in 7.7% of patients, and in all patients on the 15th day, persisting in 100% of cases up to the 9th follow-up month. During the 12th month, they were observed in 83.3% of patients. The results indicate that an anti IgA ELISA could be of great value in seroprevalence studies on human leptospirosis.

Dot-ELISA-IgM in saliva for the diagnosis of human leptospirosis using polyester fabric-resin as support (preliminary report).

In order to improve the diagnosis of human leptospirosis, we standardized the dot-ELISA for the search of specific IgM antibodies in saliva. Saliva and serum samples were collected simultaneously from 20 patients with the icterohemorrhagic form of the disease, from 10 patients with other pathologies and from 5 negative controls. Leptospires of serovars icterohaemorrhagiae, canicola, hebdomadis, brasiliensis and cynopteri grown in EMJH medium and mixed together in equal volumes, were used as antigen at individual protein concentration of 0.2 micrograms/microliters. In the solid phase of the test we used polyester fabric impregnated with N-methylolacrylamide resin. The antigen volume for each test was 1 microliter, the saliva volume was 8 microliters, and the volume of peroxidase-labelled anti-human IgM conjugate was 30 microliters. A visual reading was taken after development in freshly prepared chromogen solution. In contrast to the classic nitrocellulose membrane support, the fabric support is easy to obtain and to handle. Saliva can be collected directly onto the support, a fact that facilitates the method and reduces the expenses and risks related to blood processing.

Antigens involved in the human antibody response to natural infections with Leptospira interrogans serovar copenhageni.

Serum samples from patients with leptospirosis were screened by the microscopic agglutination test (MAT), ELISA and by immunoblotting. The latter two tests were performed with L. interrogans serovar copenhageni isolated from human blood culture. Immunoblotting with patients' sera revealed antibodies recognizing several leptospiral components in the molecular weight range 14.5-105 kDa of both IgM and IgG response. All patients' serum samples presented IgM antibodies reacting with a diffuse band of mol. wt of 14.8-22 kDa proteinase-K resistant and most reacted with bands of 26.5-28.7, 38-39 and 43-43.5 kDa. The IgG response appeared to be at variance. Examination of sequential serum samples obtained over a 4-8-month period revealed little change in the profile of antigen recognized after the 40th day of infection. Sera from healthy individuals presented IgM antibodies reacting with several leptospiral antigens, but lacked response against those of diffuse band of 14.8-22 kDa.

[An evaluation of the ELISA-IgM test in the early diagnosis of human leptospirosis]. / Avaliação do teste ELISA-IgM no diagnóstico precoce da leptospirose humana.

Thirty-seven sera samples from patients with leptospirosis icterohaemorrhagic form were studied with a time interval of 2 to 12 days between the beginning of the symptoms and the collection blood samples. It was isolated leptospira of 5 patients' hemocultures (13.5%) and from 4 of these the etiological agent pertained to the serogroup Icterohaemorrhagiae serovar copenhageni. Thirty-five of them (94.6%), including the four patients whose the etiological agent was isolated, showed reactivity in the enzyme linked immunosorbent (ELISA) IgM test. By this way, it was demonstrated that this test is important for a rapid diagnosis of human leptospirosis, even in the beginning of the disease, when there is still leptospiraemic phase.

[An immunoenzyme test (ELISA) for the detection of circulating class-IgA antibodies in human leptospirosis]. / Teste imunoenzimático (ELISA) para detecção de anticorpos circulantes da classe IgA na leptospirose humana.

An enzyme-linked immunosorbent assay ELISA was evaluated for the detection of IgA antibodies in the human leptospirosis. The assay proved to be sensitive and specific when compared with the ELISA-IgM, in the examined serum samples. The results found suggest that IgA antibodies became positive later in leptospirosis, and will can be an evolutive indicator in the development of the disease.

Standardization of dot-ELISA for the serological diagnosis of toxocariasis and comparison of the assay with ELISA.

The dot-enzyme-linked immunosorbent assay (dot-ELISA) was standardized using somatic (S) and excretory-secretory (ES) antigens of Toxocara-canis for the detection of specific antibodies in 22 serum samples from children aged 1 to 15 years, with clinical signs of toxocariasis. Fourteen serum samples from apparently normal individuals and 28 sera from patients with other pathologies were used as controls. All samples were used before and after absorption with Ascaris suum extract. When the results were evaluated in comparison with ELISA, the two tests were found to have similar sensitivity, but dot-ELISA was found to be more specific in the presence of two antigens studied. Dot-ELISA proved to be effective for the diagnosis of human toxocariasis, presenting advantages in terms of yield, stability, time and ease of execution and low cost.

[Leptospirosis in patients with anti-HIV antibodies: report of 2 cases]. / Leptospirose em doentes com anticorpos anti-HIV: relato de dois casos.

Two patients with concomitant leptospirosis and the acquired immunodeficiency syndrome (AIDS) are reported. In these cases different clinical aspects that can be attributed to simultaneity of these pathologies was not observed.

DOT-ELISA for detection of anti-Cysticercus cellulosae antibodies in human cerebrospinal fluid using a new solid-phase (resin-treated polyester fabrics). Preliminary report.

A dot enzyme-linked immunosorbent assay (DOT-ELISA) was developed to detect specific antibodies in cerebrospinal fluid (CSF) for human neurocysticercosis immunodiagnosis, with Cysticercus cellulosae antigen dotted on a new solid-phase. This was represented by sheets of a synthetic polyester fabric impregnated with a polymerized resin (N-methylol-acrylamide). A very stable preparation was thus obtained, the antigen being covalently bound by cross-linking with free N-methylol groups on the resin. Since robust, no special care was necessary for handling the solid-phase. The test could be performed at room-temperature. From 30 CSF samples assayed, 14 were positive, from a group of 15 cases of neurocysticercosis, with titers from 1 to 128; 15 other samples, from normals or other neurological diseases, were all negative. Test characteristics seem to indicate it as adequate for epidemiological surveys. A more detailed study on sensitivity, specificity, reproducibility and the use in serum samples is being conducted.