Renal involvement in leptospirosis: the effect of glycolipoprotein on renal water absorption.

BACKGROUND: Leptospirotic renal lesions frequently produce a polyuric form of acute kidney injury with a urinary concentration defect. Our study investigated a possible effect of the glycolipoprotein, (GLPc) extracted from L. interrogans, on vasopressin (Vp) action in the guinea pig inner medullary collecting duct (IMCD). METHODS: The osmotic water permeability (Pf µm/s) was measured by the microperfusion in vitro technique. AQP2 protein abundance was determined by Western Blot. Three groups were established for study as follows: Group I, IMCD from normal (ngp, n = 5) and from leptospirotic guinea-pigs (lgp-infected with L. interrogans serovar Copenhageni, GLPc, n = 5); Group II, IMCD from normal guinea-pigs in the presence of GLPc (GLPc group, n = 54); Group III, IMCD from injected animals with GLPc ip (n = 8). RESULTS: In Group I, PFS were: ngp--61.8±22.1 and lgp--8.8±12.4, p<0.01 and the urinary osmolalities were: lgp--735±64 mOsm/Kg and ngp--1,632±120 mOsm/Kg. The lgp BUN was higher (176±36 mg%) than the ngp (56±9 mg%). In Group II, the Pf was measured under GLPc (250 µg/ml) applied directly to the bath solution of the microperfused normal guinea-pig IMCDs. GLPc blocked Vp (200 pg/ml, n = 5) action, did not block cAMP (10(-4) M), and Forskolin (Fors--10(-9) M) action, but partially blocked Cholera Toxin (ChT--10(-9) M) action. GLP from L.biflexa serovar patoc (GLPp, non pathogenic, 250 µg) did not alter Vp action. In Group III, GLPc (250 µg) injected intraperitoneally produced a decrease of about 20% in IMCD Aquaporin 2 expression. CONCLUSION: The IMCD Pf decrease caused by GLP is evidence, at least in part, towards explaining the urinary concentrating incapacity observed in infected guinea-pigs.

Correlation between specific IgM levels and percentage IgG-class antibody avidity to Toxoplasma gondii.

Toxoplasmosis is an usually asymptomatic worldwide disseminated infection. In its congenital presentation it may lead to abortion or fetal malformations. Antenatal evaluation is considered of paramount importance to identify seronegative women and allow for prophylaxis. Recent improvements in sensitivity of IgM tests has made IgM detection an extremely protracted acute phase marker, and IgG avidity evaluation test became necessary. Observation has shown that a correlation can be established between IgM levels and avidity percentages, suggesting that frequently the avidity test may not be necessary. In this study we analyzed Toxoplasma gondii IgM levels of 202 samples and their IgG avidity percentages, in order to define specific levels whose IgM quantification could by itself define serodiagnosis and therefore make the avidity evaluation unnecessary. We showed that for IgM levels below 2.0 and above 6.0 serodiagnosis of toxoplasmosis could be established without need of IgG avidity test. IgM levels between these two parameters are associated with varying avidity indexes highlighting the importance of its evaluation as a means to confirm toxoplasmosis. Following this demonstration it was possible to avoid the avidity test for 75% of the cases, to reduce the turnaround time and to reduce costs.

Correlation between specific IgM levels and percentage IgG-class antibody avidity to Toxoplasma gondii / Correlação entre níveis de IgM específica e percentual de avidez de anticorpos da classe IgG ao Toxoplasma gondii

Toxoplasmosis is an usually asymptomatic worldwide disseminated infection. In its congenital presentation it may lead to abortion or fetal malformations. Antenatal evaluation is considered of paramount importance to identify seronegative women and allow for prophylaxis. Recent improvements in sensitivity of IgM tests has made IgM detection an extremely protracted acute phase marker, and IgG avidity evaluation test became necessary. Observation has shown that a correlation can be established between IgM levels and avidity percentages, suggesting that frequently the avidity test may not be necessary. In this study we analyzed Toxoplasma gondii IgM levels of 202 samples and their IgG avidity percentages, in order to define specific levels whose IgM quantification could by itself define serodiagnosis and therefore make the avidity evaluation unnecessary. We showed that for IgM levels bellow 2.0 and above 6.0 serodiagnosis of toxoplasmosis could be established without need of IgG avidity test. IgM levels between these two parameters are associated with varying avidity indexes highlighting the importance of its evaluation as a means to confirm toxoplasmosis. Following this demonstration it was possible to avoid the avidity test for 75 percent of the cases, to reduce the turnaround time and to reduce costs.

A Toxoplasmose é uma infecção universal e usualmente assintomática. A forma congênita, entretanto, pode resultar em aborto ou mal formações. Testes sorológicos estão indicados em situações onde há suspeita clínica, e na triagem pré-natal, quando são extremamente importantes para rastrear a infecção e orientar a gestante. O aumento da sensibilidade das técnicas para detecção de IgM, tornou necessário o desenvolvimento de recursos, como a avidez de IgG, visando obter novo marcador de infecção aguda. Embora exista correlação entre níveis de IgM e grau de avidez de IgG, a maioria dos testes de avidez associa-se a níveis baixos de IgM, sugerindo que o teste de avidez não fosse necessário. Portanto, correlacionamos níveis de IgM de 202 amostras com seu respectivo nível de avidez de IgG, dirigidos contra o Toxoplasma, objetivando estabelecer valores claros para a sua indicação. Pôde-se observar que, para IgM < 2,0 e > 6,0, a definição sorológica pode ser feita independentemente da avidez. Níveis de IgM dentro desse intervalo associam-se a índices variados de avidez e, portanto, ressaltam a importância deste teste para definição sorológica do quadro. Com essa abordagem, foi possível diminuir a indicação do teste de avidez em 75 por cento, reduzir o tempo para liberação dos resultados e o custo unitário do teste para IgM.