Inhibition of neuronal nitric oxide synthase activity does not alter vasopressin secretion in septic rats.

BACKGROUND/PURPOSE: During the early phase of sepsis, hypotension is accompanied by increase of plasma vasopressin hormone (AVP) levels, which decline during the late phase. This hypotension is due in part to increase of nitric oxide (NO) synthesis by nitric oxide synthase (NOS) enzyme. Neuronal isoform of this enzyme (nNOS) is present in vasopressinergics neurons of hypothalamus, but its role in vasopressin secretion during sepsis is unknown. METHODS: We evaluated the role of nNOS in NO production and vasopressin secretion during sepsis. Wistar rats received 7-nitroindazole (50 mg/kg, i.p.), an inhibitor of nNOS activity, or vehicle and were submitted to septic stimulus by cecal ligation and puncture (CLP). At the time points 0, 4, 6, 18 and 24 h after sepsis induction the animals were decapitated and neurohypophysis and hypothalamus were removed for analysis of vasopressin content and NOS activity, respectively. Hematocrit, serum sodium, osmolality, proteins and plasmatic AVP were quantified. RESULTS: Mortality was not affected by 7-nitroindazole (7-NI). Sodium and plasma proteins levels decreased after CLP and the treatment anticipated the protein loss, and delayed serum sodium decrease. Septic animals treated with 7-NI showed decrease of osmolality 4 h after CLP. Nitric oxide synthase activity in hypothalamus increased at 4 and 24 h after CLP and was reduced with 7-NI. Neurohypophysis content of AVP diminished after CLP and 7-NI did not alter this parameter. Plasma AVP levels increased at 6 h and decreased 18 and 24 h after CLP. Treatment with 7-NI did not alter plasma vasopressin levels. CONCLUSION: We concluded that nNOS does not have a substantial role in vasopressin secretion during experimental sepsis.

Advances in malaria vaccine development: report from the 2017 malaria vaccine symposium.

The Malaria Vaccine Symposium occurred at Johns Hopkins University in Baltimore, MD, USA on April 25th, 2017, coinciding with World Malaria Day and the WHO announcement that the RTS,S malaria vaccine would begin pilot implementation programs in Ghana, Kenya, and Malawi in 2018. Scientists from several disciplines reported progress on an array of malaria vaccine concepts and product candidates, including pre-erythrocytic vaccines that prevent infection, blood-stage vaccines that limit infection and disease, and transmission-blocking vaccines that interrupt the spread of infection. Other speakers highlighted the immunological and genetic considerations that must be addressed by vaccinologists to yield the most efficacious vaccines. Here, we highlight the advances in malaria vaccinology that were reported at the symposium.

Morphological and physiological characteristics of a virulent and zoonotic assemblage A Giardia duodenalis canine strain.

Giardiasis is an intestinal parasitosis that affects millions of people worldwide and is considered a zoonotic disease. Frequently in contact with humans, dogs are the main host involved in this zoonotic transmission. Here, we compared some aspects of Giardia duodenalis biology between two strains: a recently isolated dog strain (BHFC1) and a human reference strain (Portland-1). Growth curve analysis revealed that BHFC1 trophozoites multiply faster than the human isolate Portland-1 in axenic culture, but has a lower rate of cysts formation. Scanning electron microscopy revealed that BHFC1 trophozoites have the same conventional shape and morphological structures expected for G. duodenalis trophozoites, but presented a more prominent flange. For the best of our knowledge, this work is the first description of morphological aspects and encystation process of a G. duodenalis strain isolated from a dog. Since BHFC1 and Portland-1 have been maintained in axenic cultures for different periods of time, differences observed in growth, encystation rates and flange size may be attributed to adaptation of Portland-1 to axenic culture and lack of the environmental pressures. BHFC1 can be useful as tool for better understanding of Giardia duodenalis biology.

Giardiasis as a neglected disease in Brazil: Systematic review of 20 years of publications.

INTRODUCTION: Giardiasis is an intestinal infection that affects more than two hundred million people annually worldwide; it is caused by the flagellated protozoan Giardia duodenalis. In tropical countries and in low or middle-income settings, like Brazil, its prevalence can be high. There is currently no systematic review on the presence of G. duodenalis in patients, animals or water sources in Brazil. METHODS: This systematic review was performed according to recommendations established by Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). As databases for our searches, we have used PubMed, Embase, Scopus and the Brazilian database SciELO using the keywords «Giardia*¼ and «Brazil¼. RESULTS: This systematic review identified research studies related to G. duodenalis in water, giardiasis in animals, prevalence of giardiasis across Brazilian regions, genotyping of strains isolated in humans, and giardiasis in indigenous populations. We also propose a network of G. duodenalis transmission in Brazil based on genotypes analyses. CONCLUSION: This is the first time within the last twenty years that a review is being published on the occurrence of G. duodenalis in Brazil, addressing relevant issues such as prevalence, molecular epidemiology and analytical methods for parasite detection.

Genotyping and Descriptive Proteomics of a Potential Zoonotic Canine Strain of Giardia duodenalis, Infective to Mice.

The zoonotic potential of giardiasis, as proposed by WHO since the late 70's, has been largely confirmed in this century. The genetic assemblages A and B of Giardia duodenalis are frequently isolated from human and canine hosts. Most of the assemblage A strains are not infective to adult mice, which can limit the range of studies regarding to biology of G. duodenalis, including virulence factors and the interaction with host immune system. This study aimed to determine the infectivity in mice of an assemblage A Giardia duodenalis strain (BHFC1) isolated from a dog and to classify the strain in sub-assemblages (AI, AII, AIII) through the phylogenetic analysis of beta-giardin (bg), triose phosphate isomerase (tpi) and glutamate dehydrogenase (gdh) genes. In addition, the proteomic profile of soluble and insoluble protein fractions of trophozoites was analyzed by 2D-electrophoresis. Accordingly, trophozoites of BHFC1 were highly infective to Swiss mice. The phylogenetic analysis of tpi and gdh revealed that BHFC1 clustered to sub-assemblage AI. The proteomic map of soluble and insoluble protein fractions led to the identification of 187 proteins of G. duodenalis, 27 of them corresponding to hypothetical proteins. Considering both soluble and soluble fractions, the vast majority of the identified proteins (n = 82) were classified as metabolic proteins, mainly associated with carbon and lipid metabolism, including 53 proteins with catalytic activity. Some of the identified proteins correspond to antigens while others can be correlated with virulence. Besides a significant complementation to the proteomic data of G. duodenalis, these data provide an important source of information for future studies on various aspects of the biology of this parasite, such as virulence factors and host and pathogen interactions.