RESISTANCE TO OXAMNIQUINE OF A Schistosoma mansoni STRAIN ISOLATED FROM PATIENT SUBMITTED TO REPEATED TREATMENTS

A strain of Schistosoma mansoni (R1) was isolated from patient previously submitted to four treatments with oxamniquine, and to another one with praziquantel. The results obtained with chemotherapeutic test, by using oxamniquine in mice infected with the strains R1 and LE (standard), showed an evident resistance to the drug in worms of the strain R1. Thus, at the dose of 250 mg/kg oxamniquine, all mice (17) infected with the LE strain did not show surviving worms, whereas 12 out of 17 mice infected with the R1 strain presented surviving worms. At the dose of 200 mg/kg, the LE strain showed recovery rates of 1.06% and 20.58%, whereas the R1 strain presented 18.57% and 61.14%, for male and female worms, respectively. At the dose of 100 mg/kg, the recovery of male worms was 2.6% for the LE strain, and 29.9% for the R1 strain. At the same dose, the recovery of females did not show statistically significant differences between the two strains (LE = 76.38%, R1 = 79.12%). Praziquantel showed similar antischistosomal activity against both studied strains, when administered at the dose of 500 mg/kg

Immunoglobulin Fc receptors in clinical strains of Staphylococcus aureus do not confer resistance to Phagocytosis in an in vitro assay

Staphylococcus aureus binds Immunoglobulin G (IgG) on its external surface due to the presence of specific receptors for the Fc domain of this immunoglobulin. This mechanism represents a kind of camouflage against phagocytic cells. In order to confirm that possibility an in vitro evaluation of the phagocytic activity of leukocytes polymorpho-nuclear (PMN) against strains of Staphylococcus aureus was done, comparing 18 strains isolated from clinical samples and 16 from healthy individuals. The presence of Fc receptors was evaluated by haemagglutination (HA) with erythrocytes group A after incubation of the strains with IgG anti blood group A. Phagocytosis of S. aureus was carried out by mixing live bacteria with a suspension of human PMN and incubating at 37 °C for 1 h; survivors were counted as colony forming units by plating. The strains from clinical specimens showed higher HA than those from healthy individuals (p = 0.01); but the former were killed more efficiently than the latter (80-90% and 40%, respectively). It is may be possible that S. aureus showed different behavior in vivo, where could express other virulence factors to prevent the action of phagocytes.

Cryoglobulinemia in chronic hepatitis C: clinical aspects and response to treatment with interferon alpha and ribavirin

INTRODUCTION: The main extra-hepatic manifestation of hepatitis C is mixed cryoglobulinemia (MC). The aim of this study was to evaluate its prevalence among patients with chronic hepatitis C (CHC), to correlate its presence to host and virological variables and to the response to combined therapy with interferon-alpha and ribavirin. CASUISTIC AND METHODS: 202 CHC naive patients (136 with chronic hepatitis and 66 with cirrhosis) were consecutively evaluated for the presence of cryoglobulins. Cryoprecipitates were characterized by immunoelectrophoresis and classified according to the Brouet's criteria. RESULTS: The prevalence of MC was 27% (54/202), and 24% of them (13/54) showed major clinical manifestation of the disease. Even though type III MC was more frequent (78%), symptomatic MC was more common in type II MC. The presence of cirrhosis (RR = 2.073; IC95% = 1.029 - 4.179; p = 0.041), and age of the patients (RR = 1.035; IC95% = 1.008 - 1.062; p = 0.01) were independently associated with the presence of cryoglobulins. No relationship was found with viral load and genotype. 102 patients were treated with interferon alpha and ribavirin. Among these, 31 had MC. Sustained virological response (around 30%) was similar in patients with and without MC (p = 0.971). CONCLUSION: MC represents a prevalent complication in patients with CHC, specially older and cirrhotic patients. Only 24% of these patients show clinical manifestation of the disease, specially those with type II MC. The presence of MC did not affect the response to therapy.

AMERICAN CUTANEOUS LEISHMANIASIS WITH UNUSUAL CLINICAL PRESENTATION AND RESPONSE TO TREATMENT

The clinical manifestations and prognosis of cutaneous leishmaniasis (CL) can be influenced by the immune response of the patient and the species of the parasite. A case of atypical clinical presentation of CL, with development of non-characteristic lesions, poor response to therapy, and a long time to resolution is reported. Confirmatory laboratory tests included parasite detection, indirect immunofluorescence, Montenegro skin test, polymerase chain reaction, and parasite identification by multilocus enzyme electrophoresis. The parasite was identified as Leishmaniabraziliensis. The lesion was unresponsive to three complete courses of N-methylglucamine antimoniate intramuscular, and to treatment with pentamidine. The patient did not tolerate amphotericin B. The lesion finally receded after treatment with intravenous N-methylglucamine antimoniate. It is essential to ensure the accuracy of diagnosis and the appropriate treatment, which can include the use a second choice drug or a different route of administration.

Plasmodium vivax resistance to chloroquine (R2) and mefloquine (R3) in Brazilian Amazon region

We report for the first time a patient with malaria due to Plasmodium vivax who showed R2 resistance to chloroquine and R3 resistance to mefloquine in the Brazilian Amazon region based on WHO clinical criteria for diagnosis of malaria resistance. Failure was observed with unsupervised oral chloroquine, chloroquine under rigorous supervision and mefloquine in the same scheme. Finally, the patient was cured with oral artesunate.

Psychosocial factors associated with adherence to treatment and quality of life in people living with HIV/AIDS in Brazil

Objective: The objective of this article was to investigate the biopsychosocial factors that influence adherence to treatment and the quality of life of individuals who have been successfully following the HIV/AIDS treatment. Methods: It is a cross-sectional study carried out with 120 HIV positive participants in the south of Brazil. Among the variables studied, of note are: perceived stress, social support, symptoms of anxiety and depression and quality of life. Results: The results show that a moderate to high adherence to the treatment paired with a strong sense of social support indicate a higher quality of life. Conclusion: The combination of social support and antiretroviral treatment have an impact on physical conditions, improving immune response and quality of life.

Role Of MMP-2 and MMP-9 in Resistance to Drug Therapy in Patients with Resistant Hypertension

AbstractBackground:Despite the increased evidence of the important role of matrix metalloproteinases (MMP-9 and MMP‑2) in the pathophysiology of hypertension, the profile of these molecules in resistant hypertension (RHTN) remains unknown.Objectives:To compare the plasma levels of MMP-9 and MMP-2 and of their tissue inhibitors (TIMP-1 and TIMP-2, respectively), as well as their MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios, between patients with controlled RHTN (CRHTN, n=41) and uncontrolled RHTN (UCRHTN, n=35). In addition, the association of those parameters with clinical characteristics, office blood pressure (BP) and arterial stiffness (determined by pulse wave velocity) was evaluate in those subgroups.Methods:This study included 76 individuals diagnosed with RHTN and submitted to physical examination, electrocardiogram, and laboratory tests to assess biochemical parameters.Results:Similar values of MMP-9, MMP-2, TIMP-1, TIMP-2, and MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios were found in the UCRHTN and CRHTN subgroups (P>0.05). A significant correlation was found between diastolic BP (DBP) and MMP-9/TIMP-1 ratio (r=0.37; P=0.02) and DPB and MMP-2 (r=-0.40; P=0.02) in the UCRHTN subgroup. On the other hand, no correlation was observed in the CRHTN subgroup. Logistic regression models demonstrated that MMP-9, MMP-2, TIMP-1, TIMP-2 and their ratios were not associated with the lack of BP control.Conclusion:These findings suggest that neither MMP-2 nor MMP-9 affect BP control in RHTN subjects.

Development of cell mediated immunity to flagellar antigens and acquired resistance to infection by Trypanosoma cruzi in mice

Modulation by BCG and/or cyclophosphamide of sensitization of mice with flagellar fraction (a tubulin-enriched fraction) prevented death of mice challenged with T. cruzi CL strain trypomastigotes recovered from Vero cells. A methodology was ceveloped to assay specific antigens and to determine optimal doses for sensitization and elicitation of DTH in mice. CL strain is predominantly myotropic strain which does not produce important parasitism of mononuclear phagocyte cells; these cells appear to control infection when activated in vivo. Maximum protection was seen in this study when BCG and cyclophosphamide were associated, but protection was observed also when cyclophosphamide, that prevents supressor T cells, was applied 2 days before flagellar fraction sensitization in normal mice. These experiments suggested that the macrophage may have an important role in the early phases of infection particularly when nonspecific stimulation is associated with specific sensitization. A correlation betwen delayed hypersensitivity to parasite antigens and protection was observed.

Anti-schistosomal drugs: observations on the mechanism of drug resistance to hycanthone, and on the involvement of host antibodies in the mode of action of praziquantel

This paper reports recent observations from our laboratory dealing with the anti-schistosome drugs hycanthone (HC) and praziquantel (PZQ). In particular, we discuss a laboratory model of drug resistance to HC in Schistosoma mansoni and show that drug sensitive and resistant lines of the parasite can be differentiated on the basis of restriction fragment length polymorphisms using homologous ribosomal gene probes. In addition, we summarize data demonstrating that effective chemotherapy of S. mansoni infection with PZQ in mice requires the presence of host anti-parasite antibodies. These antibodies bind to PZQ treated worms and may be involved in an antibody-dependent cellular cytotoxicity reactions which result in the clearance of worms from the vasculature.

Methods for field detection of resistance to temephos in simuliids. Larval esterase level and topical application of the insecticide to adults

Two practical field methods for indirect detection of simuliid populations resistant to temephos are proposed. The first is based on high esterase activity in resistant larvae and involves adaptations of a filter paper test in which faintly stained spots indicate susceptible populations and strongly stained ones reveal populations resistant to temephos. The second is based on the resistance to the larvicide when adults are topically exposed, and involves the use of diagnostic doses obtained by the comparison between the LD50 for susceptible and resistant populations. The relevance of such methods is discussed in order to help resistance detection in Simulium pertinax Kollar control programmes.

Comparative Histopathology of Biomphalaria glabrata, B. tenagophila and B. straminea with Variable Degrees of Resistance to Schistosoma mansoni Miracidia

A comparative histopathological study of three snails species - Biomphalaria glabrata, B. tenagophila and B. straminea - which had been infected with Schistosoma mansoni miracidia revealed similar qualitative features, consisting of areas of sporocyst proliferation and differentiation associated with reactive host reaction, at the time they were actively eliminating great number of cercariae. However, in specimens that were exposed to miracidia but failed to eliminate cercariae later on, different histopathological pictures were observed in different snail species. While B. glabrata exhibited frequent focal (granulomatous) proliferation of amebocytes in several organs, B. tenagophila and B. straminea only rarely showed such reactive changes, suggesting that the mechanism of resistance to miracidial infection probably follows different pathways in the snail species studied

Resistance to Starvation of Triatoma rubrofasciata (De Geer, 1773) under Laboratory Conditions (Hemiptera: Reduviidae: Triatominae)

The present work aims at learning the period of resistance to starvation (molting/death) of Triatoma rubrofasciata in different stages of development and the respective loss of weight until death. Eggs of specimens from the greater area of the city of São Luis in the State of Maranhão, Brazil, yielded approximately 300 nymphs. These nymphs were placed in labelled Borrel glasses, in which they were weekly fed on rats (Rattus norvegicus), until reaching the stage to be observed. The experiments were conducted in a climatic chamber regulated at 29 ± 1° C, 70% relative humidity and 12 hr photoperiod. The resistance to starvation increased according to the stage of development, except for adult bugs, whose results were similar to the 3rd stage nymphs. In all these development stages there was an abrupt loss of weight in the first week, followed by a gradual loss until death. Comparing this work with those of other authors, it was observed that T. rubrofasciata is among the less resistant triatomine species.