f Schistosomiasis is a chronic and debilitating disease caused by a trematode of the genus Schistosoma and affects over 207 million people. Chemotherapy is the only immediate recourse for minimizing the prevalence of this disease and involves predominately the administration of a single drug, praziquantel (PZQ). Although PZQ has proven efficacy, there is a recognized need to develop new drugs as schistosomicides since studies have shown that repeated use of this drug in areas of endemicity may cause a temporary reduction in susceptibility in isolates of Schistosoma mansoni. Hydrazones, thiosemicarbazones, phthalimides, and thiazoles are thus regarded as privileged structures used for a broad spectrum of activities and are potential candidates for sources of new drug prototypes. The present study determined the in vitro schistosomicidal activity of 10 molecules containing these structures. During the assays, parameters such motility and mortality, oviposition, morphological changes in the tegument, cytotoxicity, and immunomodulatory activity caused by these compounds were evaluated. The results showed that compounds formed of thiazole and phthalimide led to higher mortality of worms, with a significant decline in motility, inhibition of pairing and oviposition, and a mortality rate of 100% starting from 144 h of exposure. These compounds also stimulated the production of nitric oxide and tumor necrosis factor alpha (TNF-␣), thereby demonstrating the presence of immunomodulatory activity. The phthalyl thiazole LpQM-45 caused significant ultrastructural alterations, with destruction of the tegument in both male and female worms. According to the present study, phthalyl thiazole compounds possess antischistosomal activities and should form the basis for future experimental and clinical trials.

Few studies have examined the cellular immune response of ticks, and further research on the characterization of the hemocytes of ticks is required, particularly on those of Rhipicephalus sanguineus (Latreille) because of the medical and veterinary importance of this tick. The aims of this study were to characterize the morphology and the ultrastructure of the different types of hemocytes of adult R. sanguineus and to determine the population abundance and the ultrastructural changes in the hemocytes of ticks infected with Leishmania infantum. The hemocytes were characterized through light and transmission electron microscopy. Within the variability of circulating cells in the hemolymph of adult R. sanguineus, five cell types were identified, which were the prohemocytes, plasmatocytes, granulocytes, spherulocytes, and adipohemocytes. The prohemocytes were the smallest cells found in the hemolymph. The plasmatocytes had polymorphic morphology with vesicles and cytoplasmic projections. The granulocytes had an elliptical shape with the cytoplasm filled with granules of different sizes and electrodensities. The spherulocytes were characterized by several spherules of uniform shapes and sizes that filled the entire cytoplasm, whereas the adipohemocytes had an irregular shape with multiple lipid inclusions that occupied almost the entire cytoplasmic space. The total counts of the hemocyte population increased in the group that was infected with L. infantum. Among the different cell types, the numbers increased and the ultrastructural changes occurred in the granulocytes and the plasmatocytes in the infected group of ticks.

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Introduction:The essential oil Mentha x villosa (MVEO) has a wide range of actions, including antibacterial, antifungal, antiprotozoal and schistosomicidal actions. The present study aimed to investigate the ultrastructural changes of MVEO on the tegument of adult Schistosoma mansoni. Materials and Methods:Different concentrations of MVEO were tested on S. mansoni adult worms in vitro. Ultrastructural changes on the tegument of these adult worms were evaluated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results:The MVEO caused the death of all worms at 500 μg mL-1 after 24 h. After 24h of 500 μg mL-1 MVEO treatment, bubble lesions were observed over the entire body of worms and they presented loss of tubercles in some regions of the ventral portion. In the evaluation by TEM, S. mansoni adult worms treated with MVEO, 500 μg mL-1, presented changes in the tegument and vacuoles in the syncytial matrix region. Glycogen granules close to the muscle fibers were visible. Conclusion:The ability of MVEO to cause extensive ultrastructural damage to S. mansoni adult worms correlates with its schistosomicidal effects and confirms earlier findings with S. mansoni.

The aim of this study was to characterize the ultrastructural effects caused by β-lactam antibiotics in Klebsiella pneumoniae isolates. Three K. pneumoniae clinical isolates were selected for the study with resistance profiles for third-generation cephalosporins, aztreonam, and/or imipenem and with different resistance genes for extended-spectrum β-lactamases (ESBL) or Klebsiella pneumoniae carbapenemase (KPC). Two K. pneumoniae isolates obtained from the microbiota, which were both resistant to amoxicillin and ampicillin, were also analyzed. In accordance with the susceptibility profile, the clinical isolates were subjected to subminimum inhibitory concentrations (sub-MICs) of cefotaxime, ceftazidime, aztreonam, and imipenem and the isolates from the microbiota to ampicillin and amoxicillin, for analysis by means of scanning and transmission electron microscopy. The K. pneumoniae isolates showed different morphological and ultrastructural changes after subjection to β-lactams tested at different concentrations, such as cell filamentation, loss of cytoplasmic material, and deformation of dividing septa. Our results demonstrate that K. pneumoniae isolates harboring different genes that encode for β-lactamases show cell alterations when subjected to different β-lactam antibiotics, thus suggesting that they possess residual activity in vitro, despite the phenotypic resistance presented in the isolates analyzed.

Aims: To investigate the effects of the lectin from Punica granatum sarcotesta (PgTeL) on growth, viability, cell structure, biofilm formation and chitinase activity of Listeria monocytogenes. In addition, the effect of PgTeL on the adhesion and invasion of human cells (HeLa) was determined. Methods and Results: PgTeL showed bacteriostatic and bactericidal effects on the strains L. monocytogenes N53-1 and EGD-e, causing morphometric alterations, cell aggregation, strong deformation and cell disruption. PgTeL inhibited biofilm formation by EGD-e and N53-1 and also interfered with the adhesion and invasion processes of EGD-e and N53-1 in HeLa cells. Finally, the chitinase activity of L. monocytogenes EGD-e was reduced in the presence of PgTeL, which can be involved in the inhibition of adhesion process. Conclusion:PgTeL is an antibacterial agent against L. monocytogenes, inhibiting growth and promoting cell death, as well as impairing biofilm formation and bacterial adhesion and invasion into human cells. Significance and Impact of the Study: The results stimulate future investigations on the potential of PgTeL for protection of contamination in food products.

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