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Flatworms are known for their remarkable regenerative ability, one which depends on totipotent cells known as germinative cells in cestodes. Depletion of germinative cells with hydroxyurea (HU) affects the regeneration of the parasite. Here, we studied the reduction and recovery of germinative cells in T. crassiceps cysticerci after HU treatment (25 mM and 40 mM of HU for 6 days) through in vitro assays. Viability and morphological changes were evaluated. The recovery of cysticerci's mobility and morphology was evaluated at 3 and 6 days, after 6 days of treatment. The number of proliferative cells was evaluated using EdU. Our results show morphological changes in the size, shape, and number of evaginated cysticerci at the 40 mM dose. The mobility of cysticerci was lower after 6 days of HU treatment at both concentrations. On days 3 and 6 of recovery after 25 mM of HU treatment, a partial recovery of the proliferative cells was observed. Proteomic and Gene Ontology analyses identified modifications in protein groups related to DNA binding, DNA damage, glycolytic enzymes, cytoskeleton, skeletal muscle, and RNA binding.

Cysticercosis is the presence of Taenia solium larval stage in tissues such as central nervous system, skin, muscles and eye globe. The current treatment is based on albendazole and praziquantel which already present resistance reports. Therefore, the search for alternative treatments is paramount. The aim of this study was to determine the effect of flubendazole and nitazoxanide on cytoskeleton proteins from Taenia crassiceps cysticerci, an experimental model for cysticercosis. Cysticerci were cultured in RPMI supplemented medium containing nitazoxanide and/or flubendazole. 24 h after the exposure the cysticerci were processed for scanning and transmission electron microscopy and for protein analysis of the cytoskeleton. The proteins were detected through 1D electrophoresis and identified through Western Blot. Nitazoxanide exposure increased tubulin and actin quantifications in T. crassiceps cysticerci. While flubendazole alone and the drugs combinations induced an increase in α-tubulin and actin and decreased β-tubulin quantifications in the parasite. Morphological changes such as swelling and rupture of vesicle, stiff membrane, decrease in movements were observed when the cysticerci were incubated with the different compounds. In conclusion the drugs induced significative impact in the parasite`s cytoskeleton and may be considered as alternative treatments for cysticercosis., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Taenia crassiceps is an experimental model used for cysticercosis studies and has suffered metabolic analyzes regarding the effect of anthelminthic drugs. The metabolic analyses are useful tools to determine the drugs mode of action and the parasite`s survival mechanisms. The energetic pathways are good candidates for this kind of approach as they are essential for the parasite`s survival and adaptation to the environment. In this review we discuss the anthelminthic drugs mode of action and its metabolic impact on Taenia crassiceps cysticerci., Competing Interests: Declaration of Competing Interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Neurocysticercosis (NCC) is the most common helminthic brain infection related to epilepsy. Only albendazole (ABZ) and praziquantel are used in its treatment. The development of new therapeutics has been encouraged. Taenia crassiceps cysticerci intracranial infection is the experimental model used in NCC studies. This study evaluated the histopathology of the brains of BALB/c mice experimentally infected with T. crassiceps cysticerci after the treatment with the ABZ/nitazoxanide (NTZ) combination. Thirty days after the inoculation the mice received an oral single dose of the ABZ/NTZ combination (40 mg kg-1 each). The control groups were treated with: NaCl 0.9%; ABZ or NTZ. The histopathologic evaluation of the brains was performed 24 h after treatment. The ABZ treatment induced discrete mononuclear inflammatory infiltration, meningitis, gliosis, hyperaemia and hippocampus compression; moderate ependimitis and oedema. The NTZ treatment induced accentuated inflammatory infiltration, foamy macrophages, ependimitis, choroiditis, gliosis and hyperaemia and moderate oedema. The ABZ/NTZ combination treatment induced a significant decrease in the polymorphonuclear inflammatory infiltration, ependimitis, choroiditis, gliosis, hyperaemia and ventriculomegaly in comparison with the other groups. The cysticerci showed destruction of the tegument not observed in other groups. The ABZ/NTZ combination is efficient as the parasite showed signs of destruction and lower damage to the host's tissue.

The benzimidazole derivative, 6-chloro-5-(2,3-dichlorophenoxy)-2-(trifluoromethyl)-1H-benzimidazole (RCB15), has a similar mode of action and efficacy as albendazole, a commonly used anthelminthic drugs. The aim of this study was to evaluate its influence on the tricarboxylic acid cycle in Taenia crassiceps cysticerci. The parasites were cultured in supplemented RPMI medium containing albendazole sulfoxide (ABZSO) or RCB15, for 24 h. Then, frozen in liquid nitrogen for organic metabolites extraction. Samples were analyzed by high performance liquid chromatography and organic acids of the tricarboxylic acid cycle were detected. It was possible to observe changes in the concentrations of all acids involved in this metabolic pathway, with the exception of α-ketoglutarate, which was not detected in the control group neither in most of the treated groups. It indicates that the parasite presented a partial inhibition of the tricarboxylic acid cycle. The significant increase in the concentration of citrate, oxaloacetate and succinate in the RCB15 treated groups may indicate an activation of the fumarate reductase pathway, leading to metabolic distress. Therefore RCB15 may be considered an alternative for the treatment of tissue parasitic diseases, since it induced changes in the main metabolic pathway of the parasite., Competing Interests: Declaration of Competing Interest None, (Copyright © 2019 Elsevier B.V. All rights reserved.)

Nitazoxanide (NTZ) is a broad-spectrum drug used in intestinal infections, but still poorly explored in the treatment of parasitic tissular infections. This study aimed to evaluate the in vitro responses of the energetic metabolism of T. crassiceps cysticerci induced by NTZ. The organic acids of the tricarboxylic acid cycle, products derived from fatty acids oxidation and protein catabolism were analyzed. These acids were quantified after 24 h of in vitro exposure to different NTZ concentrations. A positive control group was performed with albendazole sulfoxide (ABZSO). The significant alterations in citrate, fumarate and malate concentrations showed the NTZ influence in the tricarboxylic acid (TCA) cycle. The non-detection of acetate confirmed that the main mode of action of NTZ is effective against T. crassiceps cysticerci. The statistical differences in fumarate, urea and beta-hydroxybutyrate concentrations showed the NTZ effect on protein catabolism and fatty acid oxidation. Therefore, the main energetic pathways such as the TCA cycle, protein catabolism and fatty acids oxidation were altered after in vitro NTZ exposure. In conclusion, NTZ induced a significant metabolic stress in the parasite indicating that it may be used as an alternative therapeutic choice for cysticercosis treatment. The use of metabolic approaches to establish comparisons between anti parasitic drugs mode of actions is proposed., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Taenia solium is a parasite whose larvae (cysticerci) can locate in the central nervous system of humans and cause neurocysticercosis (NC). The introduction of cysticidal drugs such as albendazole (ABZ) for the treatment of NC has significantly improved its prognosis. However, treatment is not always effective, and the high levels of corticosteroids used to prevent inflammatory complications in this disease could be, partly, the cause of this observation. In this context, this study investigated, using the experimental mouse model of intraperitoneal infection with Taenia crassiceps, the influence of corticosteroid administration on the therapeutic efficacy of ABZ. We evaluated and compared the effects of ABZ, dexamethasone (DXM) and their combination (ABZ + DXM) on cyst viability, both in vitro and in vivo. Serum levels of IL-4, IFN-gamma, IL-6 and IL-10 were evaluated in the in vivo study. Results showed that the treatment with ABZ, in vitro and in vivo, was associated with a high number of parasites deaths. Concomitant treatment with DXM did not alter ABZ in vitro cysticidal activity but reduced its effectiveness significantly in the in vivo experimental model. Cytokine serum levels did not change significantly in treated mice compared to the controls. The results of this study are relevant as they indicate a negative effect of corticosteroids on the efficacy of cysticidal therapy. In human neurocysticercosis, control of inflammation is of great importance to most patients in order to avoid complications. Corticosteroids are generally used for this purpose and the results of this study demonstrate the need to find other therapeutic strategies. Further studies are needed to better understand the mechanisms involved., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Androgens have been shown to exert a cysticidal effect upon Taenia crassiceps, an experimental model of cysticercosis. To further inquire into this matter, the Taenia crassiceps model was used to evaluate the expression of several proteins after testosterone (T4) and dihydrotestosterone (DHT) in vitro treatment. Under 2-D proteomic maps, parasite extracts were resolved into approximately 130 proteins distributed in a molecular weight range of 10-250 kDa and isoelectrical point range of 3-10. The resultant proteomic pattern was analysed, and significant changes were observed in response to T4 and DHT. Based on our experience with electrophoretic patterns and proteomic maps of cytoskeletal proteins, alteration in the expression of isoforms of actin, tubulin and paramyosin and of other proteins was assessed. Considering that androgens may exert their biological activity in taeniids through the non-specific progesterone receptor membrane component (PGRMC), we harnessed bioinformatics to propose the identity of androgen-regulated proteins and establish their hypothetical physiological role in the parasites. These analyses yield a possible explanation of how androgens exert their cysticidal effects through changes in the expression of proteins involved in cytoskeletal rearrangement, dynamic vesicular traffic and transduction of intracellular signals.

Curcuma is a traditional ingredient of some Eastern cuisines, and the spice is heralded for its antitumoral and antiparasitic properties. In this report, we examine the effect of the curcuminoides which include curcumin, demethoxycurcumin (DMC) and bis-demethoxycurcumin (BDMC), as well as curcumin degradation products on thioredoxin glutathione reductase from Taenia crassiceps cysticerci Results revealed that both DMC and BDMC were inhibitors of TGR activity in the micromolar concentration range. By contrast, the inhibitory ability of curcumin was a time-dependent process. Kinetic and spectroscopical evidence suggests that an intermediary compound of curcumin oxidation, probably spiroepoxide, is responsible. Preincubation of curcumin in the presence of NADPH, but not glutathione disulfide (GSSG), resulted in the loss of its inhibitory ability, suggesting a reductive stabilizing effect. Similarly, preincubation of curcumin with sulfhydryl compounds fully protected the enzyme from inhibition. Degradation products were tested for their inhibitory potential, and 4-vinylguaiacol was the best inhibitor (IC50 = 12.9 μM), followed by feruloylmethane (IC50 = 122 μM), vanillin (IC50 = 127 μM), and ferulic aldehyde (IC50 = 180 μM). The acid derivatives ferulic acid (IC50 = 465 μM) and vanillic acid (IC50 = 657 μM) were poor inhibitors. On the other hand, results from docking analysis revealed a common binding site on the enzyme for all the compounds, albeit interacting with different amino acid residues. Dissociation constants obtained from the docking were in accord with the inhibitory efficiency of the curcumin degradation products., Competing Interests: The authors have declared that no competing interests exist.

Neurocysticercosis is the most frequent helminthiasis of the central nervous system and is caused by the presence of Taenia solium cysticerci. Nitazoxanide (NTZ) is an antifolate containing the pyrrolopyrimidine-based nucleus that exerts its antiprotozoal activity due to interference with the pyruvate:ferredoxin oxidoreductase (PFOR) enzyme which is essential to anaerobic energy metabolism. The aim of this work was to determine the effect of NTZ on the energetic metabolism of Taenia crassiceps cysticerci intracranially inoculated BALB /c mice. The infected animals were treated with a single oral dose of NTZ 30 days after the inoculation. Analysis of the organic acids was performed through high performance liquid chromatography. Glucose was detected only in the treated groups, alongside with a significant decrease in lactate, pyruvate and oxaloacetate concentrations which indicate an increase in gluconeogenesis. The non-detection of alpha-ketoglutarate indicated the use of the fumarate reductase pathway in all groups. It was possible to confirm the drugs mode of action due to the non-detection of acetate in the treated groups. There was an increase in the fatty acids oxidation. Therefore it was possible to observe that NTZ induces gluconeogenesis as well as the increase of alternative energetic pathways such as fatty acids oxidation in T. crassiceps cysticerci., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Based on our previous research on cysticidal drugs, we report the synthesis and evaluation of three new benzimidazole derivatives. In these compounds, the amido group was used as a bioisosteric replacement of the ester group. The molecular docking on β-tubulin revealed that the derivatives interacted through hydrogen bonding with N165, E198 and V236. All compounds showed in vitro activity against Taenia crassiceps cysts. Among them, benzimidazole 3 was found to be the most potent of the series (EC 50 0.86 µM). This compound also exhibited the highest probability of binding and the lowest binding free energy score and was therefore selected for in vivo evaluation. Results indicated that the efficacy of compound 3 was comparable to that of the reference drug, albendazole (50.39 vs. 47.16% parasite reduction). Animals treated with compound 3 seemed to tolerate this benzimidazole well, with no changes in behavior, or food and water consumption. These findings are consistent with the in silico prediction results, which indicated low toxicity risks. The pharmacokinetic study showed that the half-life and mean residence time (6.06 and 11.9 h, respectively) were long after oral administration. Together, these results indicate that this new benzimidazole derivative represents a promising structure with cysticidal activity.

Taenia crassiceps cysticerci are used as experimental model to study the host-parasite relationship and treatment of cysticercosis. One of the described mode of actions of nitazoxanide (NTZ) is to block the pyruvate ferredoxine oxidoreductase (PFOR) enzyme which is an essential enzyme to the parasite metabolism. The aim of this study was to determine the in vivo influence of one dosage of NTZ on the energetic metabolism of T. crassiceps cysticerci. Thirty days after the intraperitoneal inoculation of T. crassiceps cysticerci, BALB/c mice were orally treated with 7.5 mg/kg of NTZ. The control group was treated with physiologic solution (NaCl 0.9%). After 24 h, the animals were euthanized and the cysticerci were removed, washed, and processed for biochemical analysis. The organic acids detection occurred through high-performance liquid chromatographic and spectrophotometric analysis. While there was no difference in the glucose dosages, it was possible to observe a significant increase in the lactate concentrations and a decrease in the pyruvate concentrations of the NTZ-treated groups when compared to the control group. Also, there was a decrease in the urea and alpha-ketoglutarate concentrations. This probably occurred due to the impairment of the parasite's PFOR and nitroreductases leading an impairment of the mitochondrial aerobic pathways. In conclusion, the in vivo NTZ treatment leads to an increase in the lactic fermentation and to a decrease in the protein catabolism in T. crassiceps cysticerci.

Currently, neurocysticercosis treatment involves two drugs: albendazole and praziquantel; however, their efficacy is suboptimal and new cysticidal drugs are needed. The present paper reports the cysticidal activity of extracts of the bark from Prunus serotina against Taenia crassiceps cysts and the isolation and identification of the main components of the most active extract. Results showed that all extracts displayed in vitro cysticidal activity (EC 50 =17.9-88.5μg/mL), being the methanolic the most active and selective. Also, methanolic extract exhibited in vivo efficacy at 300mg/kg which was similar to that obtained with albendazole. Bio-guided fractionation of methanolic extract led the isolation of 2,3-dihydro-5,7-dihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one (naringenin, NGN), 3,4,5-trimethoxybenzoic acid and 1,3,5-trimethoxybenzene. NGN exhibited in vitro activity, in a time-concentration-dependent manner (EC 50 =89.3μM]. Furthermore, NGN at a dose of 376.1μmol/kg displayed similar in vivo efficacy than those obtained with albendazole at 188.4μmol/kg. NGN also caused a high level of damage in all parasite tissue in a similar manner than that observed with the methanolic extract. This study represents the first report of the cysticidal properties of the bark of P. serotina. NGN was identified as the main active compound of this specie and other studies are required to explore the potential of this flavanone as cysticidal agent., (Published by Elsevier B.V.)

Nitazoxanide (NTZ) is a broad-spectrum anti-parasitic drug used against a wide variety of protozoans and helminthes. Albendazole, its active metabolite albendazole sulfoxide (ABZSO), is one of the drugs of choice to treat both intestinal and tissue helminth and protozoan infections. However little is known regarding their impact on the metabolism of parasites. The aim of this study was to compare the in vitro effect of NTZ and ABZSO in the glycolysis of Taenia crassiceps cysticerci. The cysticerci were treated with 1.2; 0.6; 0.3 or 0.15 μg/mL of NTZ or ABZSO. Chromatographic and spectrophotometric analyses were performed in the culture medium and in the cysticerci extract. Regarding the glucose concentrations was possible to observe two responses: impair of the uptake and gluconeogenesis. The pyruvate concentrations were increased in the ABZSO treated group. Lactate concentrations were increased in the culture medium of NTZ treated groups. Therefore it was possible to infer that the metabolic acidosis was greater in the group treated with NTZ than in the ABZSO treated group indicating that this is one of the modes of action used by this drug to induce the parasite death., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The aim of this work was to develop nanosuspensions of praziquantel (PZQ) and to evaluate their influence on the energetic metabolism of cysticerci inoculated in BALB/c mice. We analyzed metabolic alterations of glycolytic pathways and the tricarboxylic acid cycle in the parasite. The nanosuspensions were prepared by precipitation and polyvinyl alcohol (PVA), poloxamer 188 (P188) and poloxamer 407 (P407) were used as stabilizers. Nanosuspension prepared with PVA had a particle size of 100nm, while P188- and P407-based nanosuspensions had particle sizes of 74nm and 285nm, respectively. The zeta potential was -8.1, -8.6, and -13.2 for the formulations stabilized with PVA, P188 and P407, respectively. Treatments of T. crassiceps cysticerci-infected mice resulted in an increase in glycolysis organic acids, and enhanced the partial reversion of the tricarboxylic acid cycle, the urea cycle and the production of ketonic bodies in the parasites when compared to the groups treated with conventional PZQ. These data suggest that PZQ nanosuspensions greatly modified the energetic metabolism of cysticerci in vivo. Moreover, the remarkable metabolic alterations produced by the stabilizers indicate that further studies on nanoformulations are required to find potentially suitable nanomedicines., (Copyright © 2016 Elsevier B.V. All rights reserved.)

An acute outbreak of Taenia hydatigena cysticercosis, causing mortality in 5 of 21 (23.8%) female lambs, is reported. Gross post-mortem examinations and histology showed Cysticercus tenuicollis as the cause of death. Biochemical parameters in infected lambs confirmed severe hepatitis. Praziquantel, given once at 15 mg/kg body weight (bw), was administered and a dramatic improvement in the clinical condition and biochemical parameters was observed up to 30 days following treatment.

The effects of testosterone (T4) and dihydrotestosterone (DHT) on the survival of the helminth cestode parasite Taenia crassiceps, as well as their effects on actin, tubulin and myosin expression and their assembly into the excretory system of flame cells are described in this paper. In vitro evaluations on parasite viability, flow cytometry, confocal microscopy, video-microscopy of live flame cells, and docking experiments of androgens interacting with actin, tubulin, and myosin were conducted. Our results show that T4 and DHT reduce T. crassiceps viability in a dose- and time-dependent fashion, reaching 90% of mortality at the highest dose used (40 ng/ml) and time exposed (10 days) in culture. Androgen treatment does not induce differences in the specific expression pattern of actin, tubulin, and myosin isoforms as compared with control parasites. Confocal microscopy demonstrated a strong disruption of the parasite tegument, with reduced assembly, shape, and motion of flame cells. Docking experiments show that androgens are capable of affecting parasite survival and flame cell morphology by directly interacting with actin, tubulin and myosin without altering their protein expression pattern. We show that both T4 and DHT are able to bind actin, tubulin, and myosin affecting their assembly and causing parasite intoxication due to impairment of flame cell function. Live flame cell video microscopy showing a reduced motion as well changes in the shape of flame cells are also shown. In summary, T4 and DHT directly act on T. crassiceps cysticerci through altering parasite survival as well as the assembly and function of flame cells.

Previously, we have studied the effect of the gold-compound auranofin (AF) on both thioredoxin-glutathione reductasa (TGR) activity and viability of Taenia crassiceps cysticerci. It was demonstrated that micromolar concentrations of AF were high enough to fully inhibit TGR and kill the parasites. In this work, the dynamics of changes in the glutathione pool of T. crassiceps cysticerci following the addition of AF, was analyzed. A dose-dependent decrease in the internal glutathione concentration, concomitant with an increase in ROS production was observed. These changes were simultaneous with the formation of glutathione-protein complexes and the export of glutathione disulfide (GSSG) to the culture medium. Incubation of cysticerci in the presence of both AF and N-acetyl cysteine (NAC) prevents all the above changes, maintaining cysticerci viability. By contrast, the presence of both AF and buthionine sulfoximine (BSO) resulted in a potentiation of the effects of the gold compound, jeopardizing cysticerci viability. These results suggest the lethal effect of AF on T. crassiceps cysticerci, observed at micromolar concentrations, can be explained as a consequence of major changes in the glutathione status, which results in a significant increase in the oxidative stress of the parasites., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A controlled trial was conducted to evaluate the efficacy of three therapeutics regimes of albendazole (ABZ) against Taenia multiceps larvae in experimental infected goats. Forty-nine goats experimentally infected with 3000 T. multiceps eggs were selected and randomly divided into treatment or control groups. Treatment with 10mg/kg for 3 days for group 1 (G1), 10mg/kg for group 2 (G2) and 20mg/kg/day for group 3 (G3) was applied 2 months after infection; group 4 (G4) served as a control group. A treatment with doses of 10mg/kg/day for 3 days on group 5 (G5) and group 6 (G6) was used as control, 5 months after the infection. The efficacy of ABZ was assessed as percentage of non-viable cysts which were determined by morphologic characteristics, movement and methyl blue staining technique. The efficacy of ABZ against 2 months old cysts was significantly different from the control and were 90.3% (28/31), 72.7% (8/11) and 73.9% (14/19) for G1, G2 and G3, respectively. No differences were observed in cyst viability between treated and control groups for 5-month old cysts. The results in this study indicate that ABZ is effective in goats against 2-month-old cysts of T. multiceps larva located in tissues outside the brain., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Neurocysticercosis (NCC) is the most common helminthic infection and neglected disease of the central nervous system. It is the leading cause of acquired epilepsy and seizures worldwide. Therefore, to study this important neglected disease, it is important to use experimental models. There is no report in the literature on how the parasite's metabolism reacts to antihelminthic treatment when it is still within the central nervous system of the host. Therefore, the aim of this study was to investigate the energetic metabolism of cysticerci experimentally inoculated in the encephala of BALB/c mice after treatment with low dosages (not sufficient to kill the parasite) of albendazole (ABDZ) and praziquantel (PZQ). BALB/c mice were intracranially inoculated with Taenia crassiceps cysticerci and, after 30 days, received treatment with low dosages of ABDZ and PZQ. After 24 h of treatment, the mice were euthanized, and the cysticerci were removed and analyzed through high-performance liquid chromatography (HPLC) to quantify the organic acids related to the energetic metabolism of the parasite. The partial reverse of the TCA cycle was enhanced by the ABDZ and PZQ treatments both with the higher dosage, as the organic acids of this pathway were significantly increased when compared to the control group and to the other dosages. In conclusion, it was possible to detect the increase of this pathway in the parasites that were exposed to low dosages of ABDZ and PZQ, as it is a mechanism that would amplify the energy production in a hostile environment.

Taenia crassiceps has been widely experimented as a model for in vitro and in vivo studies on drug responses. The purpose of this study was to treat BALB/c mice infected with T. crassiceps strain WFU with commercially available albendazole and to analyze the reduction in parasite infrapopulations. Here, we describe the reduction and apparent damage of T. crassicceps WFU cysticerci in infected mice after antihelminthic drug treatment and subsequent inoculation of those treated parasites into a naïve host. We were able to reduce significantly the parasite counts to 33 and 48% after albendazole treatment for 20 or 25 days and compared with the untreated mice. We also observed morphological damage such as the partial blebbing in the tegument and parenchyma of treated parasites, as well as disorganized musculature and the loss of cell membranes in subtegumental tissue section. However, larvae from albendazole-treated mice inoculated into the next host were able to become re-established in the next murine host due, probably, to the survival of proliferative parasite cells.

Cysticerci and tapeworms from Taenia crassiceps WFU, ORF and Taenia solium synthesize sex-steroid hormones in vitro. Corticosteroids increase the 17β-estradiol synthesis by T. crassiceps cysticerci. T. crassiceps WFU cysticerci synthesize corticosteroids, mainly 11-deoxycorticosterone (DOC). The aim of this work was to investigate whether classical steroidogenic inhibitors modify the capacity of T. crassiceps WFU cysticerci to synthesize corticosteroids and sex steroid hormones. For this purpose, T. crassiceps WFU cysticerci were obtained from the abdominal cavity of mice, pre-cultured for 24h in DMEM+antibiotics/antimycotics and cultured in the presence of tritiated progesterone ((3)H-P4), androstendione ((3)H-A4), or dehydroepiandrosterone ((3)H-DHEA) plus different doses of the corresponding inhibitors, for different periods. Blanks with the culture media adding the tritiated precursors were simultaneously incubated. At the end of the incubation period, parasites were separated and media extracted with ether. The resulting steroids were separated by thin layer chromatography (TLC). Data were expressed as percent transformation of the tritiated precursors. Results showed that after 2h of exposure of the cysticerci to 100 μM formestane, the (3)H-17β-estradiol synthesis from tritiated androstenedione was significantly inhibited. The incubation of cysticerci in the presence of (3)H-DHEA and danazol (100 nM) resulted in (3)H-androstenediol accumulation and a significant reduction of the 17β-estradiol synthesis. The cysticerci (3)H-DOC synthesis was significantly inhibited when the parasites were cultured in the presence of different ketoconazole dosis. The drug treatments did not affect parasite's viability. The results of this study showed that corticosteroid and sex steroid synthesis in T. crassiceps WFU cysticerci can be modified by steroidogenic enzyme inhibitors. As was shown previously by our laboratory and others, parasite survival and development depends on sex steroids, therefore the inhibition of their synthesis is a good starting point exploited in situations where the inhibition of steroidogenesis could help to control the infection for the development of new treatments, or replacement of the usual therapy in resistant parasite infections. We raise the possibility that these drug actions may be beneficially., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Helminth β-tubulins are the targets of benzimidazole (BZM) carbamate compounds. The specificity of the interactions between such compounds and their in vivo targets depends on the presence of specific amino acid residues in the target molecules. To discover new and effective anthelmintic drugs, we used a medicinal chemistry approach to synthesize a series of BZM derivatives that exploited the BZM moiety as a template. We have previously found that one compound, 2-(trifluoromethyl)-1H-benzimidazole (RCB20), has better in vitro and in vivo activity than albendazole sulfoxide (ABZSO). In the present study, the effect of RCB20 and ABZSO treatment on expression of Taenia crassiceps cysticerci cytoskeletal proteins such as actin, myosin II, and tubulin isoforms was examined. The effects of RCB20 and ABZSO after 11 days treatment of the parasites was evaluated by light, confocal, and electron microscopy, and by immunochemistry and immunohistochemistry. The RCB20-induced effects were more rapid than the ABZSO-induced effects on the parasites. In the RCB20-treated parasites, we observed gross-structural damage at the whole parasite level, particularly in the inner tissues and flame cells. Changes in the expression patterns of the cytoskeletal proteins, as assessed by immunohistochemistry and immunoblotting, revealed that the most important drug-induced effect on the parasites was a reduction in the expression level of tyrosinated α-tubulins. Our research findings suggest that RCB20 treatment affected posttranslational modification of parasite α-tubulin molecules, which involved removal of the α-tubulin carboxy-terminal tyrosine.

Neurocysticercosis (NCC), an infection of the brain with the larval stage of the Taenia solium tapeworm, is responsible for an estimated one-third of adult-onset epilepsy cases in regions of the world where it is endemic. Currently, anthelmintic drugs used for treatment of NCC are only partially effective, and there is, therefore, a pressing need for new therapeutic agents. Discovery of new anthelmintics with activity against T. solium has been limited by the lack of suitable sensitive assays that allow high-throughput screening. Using an in vitro culture system with Taenia crassiceps metacestodes, we demonstrate that changes in secretion of parasite-associated alkaline phosphatase (AP) and phosphoglucose isomerase (PGI) can be used to detect and quantify anthelmintic effects of praziquantel (PZQ), a drug with activity against T. solium. We applied two enzyme release assays to screen for anti-T. crassiceps activity in nonconventional antiparasitic drugs and demonstrate that nitazoxanide and artesunate induced release of both AP and PGI in differing time- and dose-related patterns. Furthermore, imatinib, a tyrosine kinase inhibitor previously reported to have parasiticidal activity against Schistosoma mansoni, also induced release of both AP and PGI in a dose-dependent manner, similar in pattern to that observed with the other anthelmintics. We also evaluated release of ATP into cyst supernatants as an indicator of drug effects but did not see any differences between treated and untreated cysts. These data provide the basis for rapid and quantitative screening assays for testing for anthelmintic activity in candidate anticestode agents.

We have shown previously that cultured Taenia crassiceps Wake Forest University (WFU) and Taenia solium cysticerci, as well as the adult worms, synthesize sex steroid hormones from [3H]steroid precursors and that androgens and oestrogens influence the in vitro development of the parasites. Glucocorticoids (GCs) are used to control the inflammation caused by T. solium cysticerci in the brain. These steroids stimulate oestrogen synthesis in several tissues. Since there is no information on the effect of GC on the endocrine function of cysticerci, we investigated the effect of natural and synthetic GCs on the synthesis of oestrogens in cultured T. crassiceps WFU cysticerci. The cysticerci were obtained from the peritoneal cavity of infected female BALB/c mice; the cysts were washed extensively and pre-cultured in Dulbecco's Modified Eagle's Medium (DMEM) plus antibiotics for 5 days. The parasites were further cultured with different doses of corticosterone, dexamethasone or the vehicle for 5 days. [3H]Dehydroepiandrosterone (3H-DHEA) was added to the media and the cysticerci were further incubated for 6 or 24 h. Media were then removed and the steroids ether-extracted. Aliquots of the media were seeded on silica gel plates and developed in solvent systems. Parasites incubated in the presence of 3H-DHEA synthesized [3H]androstenediol, [3H]testosterone and [3H]17β-oestradiol ([3H]17β-E2). The addition of 100 nm or higher corticosterone doses to the media increased [3H]17β-E2 synthesis fourfold after 24 h. Dexamethasone also increased [3H]17β-E2 synthesis. The experiments presented here show for the first time that corticosterone and the synthetic GC dexamethasone modulate the synthesis of oestrogens by cysticerci.

We report two cases of symptomatic neurocysticercosis in two migrants whose negative serology delayed appropriate treatment for 9 and 6 months, respectively. Seroconversion occurred after treatment, which was associated with paradoxical reaction in one patient. Long-term outcome was good in both patients., (© 2012 International Society of Travel Medicine.)

Background: The control of soil-transmitted helminth (STH) infections currently relies on the large-scale administration of single-dose oral albendazole or mebendazole. However, these treatment regimens have limited efficacy against hookworm and Trichuris trichiura in terms of cure rates (CR), whereas fecal egg reduction rates (ERR) are generally high for all common STH species. We compared the efficacy of single-dose versus triple-dose treatment against hookworm and other STHs in a community-based randomized controlled trial in the People's Republic of China., Methodology/principal Findings: The hookworm CR and fecal ERR were assessed in 314 individuals aged ≥5 years who submitted two stool samples before and 3-4 weeks after administration of single-dose oral albendazole (400 mg) or mebendazole (500 mg) or triple-dose albendazole (3×400 mg over 3 consecutive days) or mebendazole (3×500 mg over 3 consecutive days). Efficacy against T. trichiura, Ascaris lumbricoides, and Taenia spp. was also assessed. ALBENDAZOLE CURED SIGNIFICANTLY MORE HOOKWORM INFECTIONS THAN MEBENDAZOLE IN BOTH TREATMENT REGIMENS (SINGLE DOSE: respective CRs 69% (95% confidence interval [CI]: 55-81%) and 29% (95% CI: 20-45%); triple dose: respective CRs 92% (95% CI: 81-98%) and 54% (95% CI: 46-71%)). ERRs followed the same pattern (single dose: 97% versus 84%; triple dose: 99.7% versus 96%). Triple-dose regimens outperformed single doses against T. trichiura; three doses of mebendazole - the most efficacious treatment tested - cured 71% (95% CI: 57-82%). Both single and triple doses of either drug were highly efficacious against A. lumbricoides (CR: 93-97%; ERR: all >99.9%). Triple dose regimens cured all Taenia spp. infections, whereas single dose applications cured only half of them., Conclusions/significance: Single-dose oral albendazole is more efficacious against hookworm than mebendazole. To achieve high CRs against both hookworm and T. trichiura, triple-dose regimens are warranted., Trial Registration: www.controlled-trials.com ISRCTN47375023.

The effect of the dehydroepiandrosterone analog 16alpha-bromoepiandrosterone (EpiBr) was tested on the tapeworm Taenia crassiceps and the protist Entamoeba histolytica, both in vivo and in vitro. Administration of EpiBr prior to infection with cysticerci in mice reduced the parasite load by 50% compared with controls. EpiBr treatment induced 20% reduction on the development of amoebic liver abscesses in hamsters. In vitro treatment of T. crassiceps and E. histolytica cultures with EpiBr, reduced reproduction, motility and viability in a dose- and time-dependent fashion. These results leave open the possibility of assessing the potential of this hormonal analog as a possible anti-parasite drug, including cysticercosis and amoebiasis., (Copyright 2010 Elsevier Masson SAS. All rights reserved.)

Control of cellular redox homeostasis is a central issue for all living organisms. Glutathione and thioredoxin enzymatic redox systems are the usual mean used to achieve such a control. However, parasitic platyhelminths studied to date possess a nicotinamide adenine dinucleotide phosphate-dependent thioredoxin-glutathione reductase (TGR) as the sole redox control system. Thus, TGR is considered as a potential therapeutic target of parasitic platyhelminths, and based on this assumption, the gold compound auranofin is a potent inhibitor of TGR. The aim of this research was to investigate the effect of auranofin on metacestode (cysticerci) of Taenia crassiceps in culture. Accordingly, the time course for viability and respiration of cysticerci in culture was evaluated in the presence of this compound. After 4 h at 10 microM auranofin, 90% of cysticerci were alive, but respiration activity had declined by 50%. After 12 h, neither survivors nor respiration was detected; a LD(50) for auranofin of 3.8 microM was calculated. Interestingly, crude extracts of cysticerci pretreated with 3 microM auranofin nearly nil TGR activity (IC(50) = 0.6 microM). Zymography for TGR in polyacrylamide gel electrophoresis was conducted because the previously mentioned extracts clearly showed a dose-response inactivation of TGR toward auranofin. The killing of cysticerci by this gold compound is most likely related with TGR inactivation. Therefore, further research on the suitability of auranofin as a therapeutic tool in the treatment of cysticercosis in animals and humans is sustained.

The effect of two water-soluble polymers: pectin and polyvinylpyrrolidone in combination with beta-cyclodextrin, on the dissolution, bioavailability and cysticidal efficacy of albendazole was evaluated using a commercial suspension as reference product. The dissolution of the albendazole-beta-cyclodextrin-pectin formulation was slow and incomplete (44.7%). No statistical differences in C(max) and AUC were found between this formulation and the reference. Also its cysticidal efficacy (33%) was similar to the reference (38%). The albendazole-beta-cyclodextrin-polyvinylpyrrolidone formulation exhibited the highest dissolution rate (78.5%) and its bioavailability was also significantly increased (2.3-fold). In addition, the cysticidal activity of this formulation (83%) was greater than a commercial suspension. Our results suggest that the ternary system of albendazole-beta-cyclodextrin-polyvinylpyrrolidone could be a potential alternative for the treatment of systemic helmintic diseases and it is worth to continue its preclinical evaluation.

MAP kinases (MAPK) are involved in the regulation of cellular processes such as reproduction and growth. In parasites, the role of MAPK has been scarcely studied. Here, we describe the participation of an ERK-like protein in estrogen-dependent reproduction of the helminth parasite Taenia crassiceps. Our results show that 17beta-estradiol induces a concentration-dependent increase in the bud number of in vitro cultured cysticerci. If parasites are also incubated in presence of an ERK-inhibitor, the stimulatory effect of estrogen is blocked. The expression of ERK-like mRNA and its corresponding protein was detected in the parasite. The ERK-like protein was over-expressed by all treatments. Nevertheless, a strong induction of phosphorylation of this protein was observed only in response to 17beta-estradiol. Cross-contamination by host cells was discarded by flow cytometry analysis. Parasite cells expressing the ERK-like protein were exclusively located at the subtegument tissue by confocal microscopy. Finally, the ERK-like protein was separated by bidimensional electrophoresis and then sequenced, showing the conserved TEY activation motif, typical of all known ERK 1/2 proteins. Our results show that an ERK-like protein is involved in the molecular signalling during the interaction between the host and T. crassiceps, and may be considered as target for anti-helminth drugs design.

The Taenia genus is capable of living for long periods within its hosts. Reports have shown that this successful establishment is related to its efficient defense mechanisms against host immune response and its high tolerance to oxidative stress. In this work, we describe the genomic sequences of one Taenia solium and Taenia crassiceps typical 2-Cys peroxiredoxins (Ts2-CysPrx, Tc2-CysPrx) genes, which are 94% identical in primary sequence with the typical 2-Cys Prxs catalytic motifs. Both genes have the same genomic architecture, showing a TATA box and Initiator (Inr) sequence in their proximal promoter, two exons split by a 67-bp type III intron and one unique transcription start site located inside the Inr. We show that T. crassiceps cysticerci are highly tolerant to H(2)O(2) presenting a lethal concentration 50 of 3.0 mM and demonstrate that the typical Tc2-CysPrx gene is not induced by H(2)O(2), showing a behavior of an antioxidant housekeeping gene. This study describes for first time the gene structure of a typical 2-Cys Prx in the Taenia genus.

Despite albendazole being the drug of choice in neurocysticercosis treatment, its low solubility limits its bioavailability; therefore, more research is required in order to find new molecules with cestocidal activity and adequate aqueous solubility. A set of 13 benzimidazole derivatives were synthesized and their in vitro activities were evaluated against Taenia crassiceps cysts, using albendazole sulfoxide as reference molecule, showing that two of them exhibited good activity. Molecular modelling revealed that the cysticidal efficacy depends on the presence on the molecule of an H in the 1-position, a planar carbamate group at 2-position, and if the substituent in 5-position is voluminous, it should be orthogonal to the benzimidazole ring.

Taenia solium infections continue being a health problem in undeveloped countries, and few effective control measures against this parasite are being applied. Antimicrobial peptides (AMPs) belong to the innate immune response and capable of destroying pathogens. We tested the ability of two AMPs, Temporin A (TA) and Iseganan IB-367 (IB-367) to damage T. crassiceps cysticerci in vitro. Doses of 200 and 400 microg/ml of TA and IB-367 caused cysticerci to shrink, lose motility, the formation of macrovesicles in the tegument, as well as decreased evagination properties. These changes were observed as early as 3-6h and became more pronounced over 24h, when the morphological changes of the bladders became evident by both light and electron microscopy. Electron micrographs of cysticerci exposed to peptides showed initial changes as collapsed microvesicles in the tegument, with formation of large vesicles and extrusion of tegumentary tissues into the surrounding media, which led to complete loss of the tegument as well as shrinkage and complete loss of structure of parenchymal tissue after 24h. Peptides administered to cysticercotic mice one month post-infection in a single intraperitoneal dose of 200 or 400 microg, reduced the parasite load by 25% for IB-367, and 50% for TA. The humoral response of infected mice does not appear capable of killing surviving cysticerci. Our studies show that in vitro, AMPs severely damage the tegument and the scolex, and open a new pathway for biological drug design or the development of transgenic animals that over express these peptides capable of killing the cysticerci in vivo.

The tegumental membrane of Taenia crassiceps cysticerci contains an ATP-diphosphohydrolase (EC 3.6.1.5) which hydrolyzes purine and pyrimidine nucleoside 5'-di- and 5'-triphosphates at an optimum pH of 8.5. It is Mg(2+)-dependent and insensitive to classical ATPase and phosphatase inhibitors. In solubilized tegumental membrane the Km values varied from 220 to 480 microM and the V(max) from 370 to 748 nmol of Pi release/mg/min for nucleoside triphosphates (ATP, GTP, CTP, UTP, and TTP); for nucleoside diphosphates (ADP, GDP, CDP, and UDP) the Km values were from 260 to 450 microM and the V(max) from 628 to 1134 nmol of Pi release/mg/min. An antibody specific to CD39 shows cross-reactivity with T. crassiceps ATP-diphosphohydrolase, revealing a single protein of approximately 80 kDa. Incubation of ATP-diphosphohydrolase with FSBA inhibited ATPase and ADPase activities by 85-90%. Immunoblot analyses, the competition plot, similar inhibition by free nucleotides, the lack of effect of Mg(2+) at high concentrations, and the inactivation by FSBA of ATPase and ADPase activity strongly suggest that a single enzyme catalyzes the hydrolysis of all these nucleotides. The mechanism of ATP hydrolysis shows that ATP-diphosphohydrolase releases ADP during the catalytic cycle. Incubation of intact cysticerci with FSBA caused 70-80% inhibition of ATPase and ADPase activities, indicating that the active site of the ATP-diphosphohydrolase is oriented to the external surface of the tegument of T. crassiceps. The importance of this enzyme in the parasite-host relationship is discussed.

The aim of this work was to explore the effect of dehydroepiandrosterone (DHEA) on the establishment, growth and reproduction of the metacestode stage of the tapeworm Taenia crassiceps, both in vivo and in vitro. Administration of DHEA prior to infection in mice of both sexes reduced the parasite load by 50% compared with untreated mice. This protective effect was not associated with the immune response, since there was no effect of DHEA treatment on mRNA levels of IL-2, IFN-gamma, IL-4 or IL-10. DHEA treatment of infected mice increased androgen receptor expression in splenocytes of both sexes. Moreover, in vitro treatment of T. crassiceps with DHEA reduced reproduction, motility and viability in a dose- and time-dependent fashion. Results indicate that DHEA has strong negative direct modulatory effects on murine cysticercosis. We suggest the use of hormonal-analogues for protective purposes as a therapeutic approach to prevent murine cysticercosis.

Methods to determine viability of taeniid oncospheres following treatments with potential lethality have practical application in efforts to control transmission. Here we investigated several methods, in lieu of infectivity studies, to assess oncosphere viability and determine lethal temperature treatment regimens. In the first experiment, a standard treatment to exshell oncospheres with 0.5% hypochlorite was assessed for influence on oncosphere recovery of Taenia taeniaeformis eggs. Recovery of eggs and exshelled oncospheres decreased with increasing time in hypochlorite, which indicated that hypochlorite can damage eggs and oncospheres, translating into potential overestimation of lethality of experimental treatments. Losses in hypochlorite were accentuated when eggs were pretreated at 75 degrees C, but not lower temperatures, including 65 degrees C, indicating a sharp threshhold between 65 degrees C and 75 degrees C where eggs and oncospheres became hypersensitive to subsequent hypochlorite treatment. To further investigate this change in relation to temperature, non-vital (acridine orange, AO) and vital (propidium iodide, PI; trypan blue, TB) dyes were used to assess staining of oncospheres (exshelled or not) under conditions ranging from room temperature up to 95 degrees C. The behaviors of dyes as related to internal staining of oncospheres were described using non-linear regression and a sigmoid four-parametric model to determine the inflection point (T50). Each of the dyes differed significantly in T50 estimates, e.g. AO (69.22+/-0.53), PI (73.89+/-0.52) and TB (79.43+/-0.45). For these dyes, the T50 increased in relation to the increasing molecular weight of the dyes. Collectively, the results suggested that barriers to chemical permeability exist in eggs that breakdown incrementally with increasing temperatures above 65 degrees C. This staining behavior and the likelihood that the temperatures involved are above a lethal threshhold clarify a basic limitation in the use of vital dyes to assess oncosphere viability. The results may be relevant to other Taenia spp.

Administration of tamoxifen (an antiestrogen) produced an 80% parasite load reduction in female mice, and a weaker effect of 50% in male mice. This protective effect was associated in both sexes, with an increase in the mRNA levels of interleukin (IL)-2 (a cytokine associated with protection against cysticerci) and IL-4 (no effect on infection). tamoxifen treatment modified 17-beta estradiol production in females, whereas serum testosterone was not affected. However, the expression of the 2 types of estrogen receptor (ER), i.e., ER-alpha and ER-beta, in the spleen of infected mice of both sexes, was decreased by tamoxifen treatment. In vitro, treatment of Taenia crassiceps with tamoxifen reduced reproduction and loss of motility. These results indicate that tamoxifen treatment is a new therapeutic possibility to treat cysticercosis, because it can act at both ends of the host-parasite relationship, i.e., by increasing the cellular immune response protective against the parasite and by directly affecting the parasite's reproduction and survival.

Objectives: Neurocysticercosis is a common parasitic disease in the CNS in humans caused by the metacestode Taenia solium, with high incidence in developing countries. Albendazole is the drug of choice. However, a wide interindividual variability in the response has been reported. In order to evaluate alternative treatment options, the in vitro efficacy of nitazoxanide, its main metabolite tizoxanide as well as the tizoxanide and albendazole sulphoxide combination was tested against Taenia crassiceps cysts., Methods: T. crassiceps cysts were incubated in culture medium containing different concentrations of nitazoxanide, tizoxanide and albendazole sulphoxide (0.037-0.42 microg/mL). The effect of the tizoxanide and albendazole sulphoxide combination was evaluated in a fixed-concentration ratio (1:1). Isobolographic analyses were used to define the kind of interaction between drugs. Morphological and ultrastructural alterations over the parasite tissue were observed by light and transmission electron microscopy., Results: Nitazoxanide and tizoxanide exhibited cestocidal activity which was time-concentration-dependent. The EC(50) values were 0.15, 0.12 and 0.080 microg/mL for nitazoxanide, tizoxanide and albendazole sulphoxide, respectively. No statistical differences between EC(50) values were found, indicating that nitazoxanide and tizoxanide are equally potent as albendazole sulphoxide. The effect of the tizoxanide and albendazole sulphoxide combination was faster than that observed with each drug alone. Isobolographic analysis showed that the effect of the combination was additive. Nitazoxanide and tizoxanide had an effect on the germinal layer, where lipid droplets were found. Nitazoxanide and tizoxanide produced less damage than albendazole sulphoxide on the germinal layer. After the tizoxanide and albendazole sulphoxide combination, a high accumulation of lipid droplets within the germinal layer of the parasite was found., Conclusions: Our results suggest that nitazoxanide in combination with albendazole could be useful for treatment of cysticercosis infections. Additional in vivo studies are required to confirm this hypothesis.

Objectives: Praziquantel and albendazole are currently used for chemotherapeutic treatment of neurocysticercosis. Albendazole has been found to be more effective than praziquantel; however, it is well known that not all patients will show a complete resolution of cysts. Searching for more effective treatments, this study was designed to evaluate the effect of the combination of praziquantel and albendazole sulphoxide in a Taenia crassiceps in vitro model as well as the kind of interaction between both drugs., Methods: In order to determine the concentration that produced 50% effect (EC50), T. crassiceps cysts were incubated in culture medium containing praziquantel (0.005-0.04 microg/mL), albendazole sulphoxide (0.021-0.16 microg/mL) or the combination of praziquantel and albendazole sulphoxide in a fixed-dose ratio (1:1). The experimental concentration (EC50Exp) of the combination was determined from the concentration-response curve constructed from the combined drug treatment. Isobolographic analyses were used to define the nature of the interaction between praziquantel and albendazole sulphoxide. Morphological and ultrastuctural alterations after different treatments over the parasite tissue were observed by light and transmission electron microscopy., Results: The changes in ultrastructure were more marked with the praziquantel and albendazole sulphoxide combination. Also the cysticidal effect of the combination was observed earlier than that of each drug alone. When isobolographic analysis was employed, we found that the experimental EC50 value (0.042 microg/mL) was not significantly different from the theoretical EC50 value (0.035 microg/mL), which indicates an additive interaction between praziquantel and albendazole sulphoxide., Conclusions: Our study suggests that the combination of praziquantel and albendazole sulphoxide could potentially improve the current neurocysticercosis treatment.

The nature of the cyanide-resistant respiration of Taenia crassiceps metacestode was studied. Mitochondrial respiration with NADH as substrate was partially inhibited by rotenone, cyanide and antimycin in decreasing order of effectiveness. In contrast, respiration with succinate or ascorbate plus N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was more sensitive to antimycin and cyanide. The saturation kinetics for O2 with NADH as substrate showed two components, which exhibited different oxygen affinities. The high-O2-affinity system (Km app=1.5 microM) was abolished by low cyanide concentration; it corresponded to cytochrome aa3. The low-O2-affinity system (Km app=120 microM) was resistant to cyanide. Similar O2 saturation kinetics, using succinate or ascorbate-TMPD as electron donor, showed only the high-O2-affinity cyanide-sensitive component. Horse cytochrome c increased 2-3 times the rate of electron flow across the cyanide-sensitive pathway and the contribution of the cyanide-resistant route became negligible. Mitochondrial NADH respiration produced significant amounts of H2O2 (at least 10% of the total O2 uptake). Bovine catalase and horse heart cytochrome c prevented the production and/or accumulation of H2O2. Production of H2O2 by endogenous respiration was detected in whole cysticerci using rhodamine as fluorescent sensor. Thus, the CN-resistant and low-O2-affinity respiration results mainly from a spurious reaction of the respiratory complex I with O2, producing H2O2. The meaning of this reaction in the microaerobic habitat of the parasite is discussed.

The in vitro exposure of Taenia crassiceps cysticerci to 17-beta estradiol (E2) and progesterone (P4) stimulated their reproduction and infectivity. Testosterone (T4) and dihydrotestosterone (DHT) inhibited their reproduction and reduced their motility and infectivity. E2 and P4 increased, whereas T4 and DHT reduced, the expression of parasite c-fos and c-jun and DNA synthesis. In vitro exposure of cysticerci to sex steroids before their inoculation into recipient noninfected mice resulted in large parasite loads when pretreated with E2 and P4 and in smaller loads when pretreated with T4 and DHT To determine the possible molecular mechanisms by which sex steroids affect T. crassiceps, sex steroid receptors were amplified. Taenia crassiceps expressed estrogen receptors (both alpha and beta isoforms) and androgen receptors but no P4 receptors. These results demonstrate that sex steroids act directly on parasite reproduction by binding to a classic and specific sex steroid receptor on the parasite. The differential response of cysticerci to sex steroids may also be involved in their ability to grow faster in the murine female or feminized male host. This is the first report of direct sex steroid effects on the parasite possibly through sex steroid receptors in the cysticerci.

We investigated the minimum exposure times of prazicuantel (PZQ) and albendazole sulfoxide (ABZSO) required for their activities against Taenia cysts in vitro as well as the 50 and 99% effective concentrations. The results showed that although the effects of both drugs are time and concentration dependent, ABZSO acts much slower and is less potent than PZQ.

The cestode parasite Taenia solium is an important cause of foodborne infection throughout tropical and subtropical regions. Ingestion of pork meat infected with T. solium larvae can lead to taeniasis infection in humans. With tourism and the consumption of native food increasing, it is important to investigate potential risks of transmission associated with food preparation methods. In this study, traditional Mexican salt pickling and two methods of pork preparation (as roast pork [cochinita pibil] and in pork and beans [frijol con puerco]) were evaluated in order to determine their effects on T. solium cyst viability in infected tissue. In the control groups, all metacestodes isolated were 100% viable, and only small changes in pH (from 6.0 to 5.9) and temperature (29 to 30 degrees C) were recorded. No viable cysts were detected after 12 and 24 h of salt pickling. The pH of the meat during salting dropped from 6.0 to 5.3. Osmotic changes and dehydration from the salting, rather than a change in pH, could be considered the main cause of cyst death. Temperatures of >65 degrees C damaged T. solium metacestodes in roast pork and in pork and beans. The results of this study indicate that if traditional pork dishes are prepared properly, T. solium cysts are destroyed. The criteria used in this study to evaluate the viability of tissue cysts are discussed.

Cysticercosis, the infection by the larvae of Taenia solium, is a major cause of acquired epilepsy in the world; it also causes significant economic loss because of contaminated pork. This disease is endemic in most developing countries and no control strategy has yet been proven efficient and sustainable. To further evaluate the full potential of single-dose oxfendazole treatment for pigs as a control measure, 20 pigs with cysticercosis were treated with oxfendazole and later matched with 41 naive pigs and exposed to a natural challenge in a hyperendemic area. New infections were found by serologic testing in 15 of the 32 controls (47%), and by the presence of cysts at necropsy in 12 of them (37%). Only minute residual scars were detected in the carcasses of oxfendazole-treated pigs. Pigs with cysticercosis, once treated with oxfendazole, are protected from new infections for at least three months.

The gravid proglottids of Taenia saginata from human infection before and after treatment of patient with niclosamide (Yomesan) were used for studies on oncosphere envelope ultrastucture. The envelopes examined were intact after drug treatment. The samples from niclosamide-treated and untreated patients were similar with respect to number and kinds of the protective structures surrounding the oncospheres inside gravid proglottids. Their morphology was generally similar to this described earlier for other taeniid species. Details of the ultrastructure of oncospheral envelopes from niclosamide-treated patients are presented in the paper. Contamination of the environment with eggs from treated patients, particularly in poor sanitary conditions, is discussed.

Following the oral administration of metacestodes of two isolates of Taenia crassiceps, the enteral establishment and survival of the strobilar stage were examined in golden hamsters (Mesocricetus auratus), Mongolian gerbils (Meriones unguiculatus) and laboratory mice. The origin of the isolates was Microtus montebelli caught in Japan in 1985 or Clethrionomys rutilus captured on St. Lawrence Island, Bering Sea, in 1988 (abbreviated as JPN and SLI isolates), respectively. The enteral establishment of the SLI isolate was distinctly higher than that of the JPN isolate in golden hamsters and mice, whereas the difference was marginal in Mongolian gerbils. All initially-established parasites survived to become gravid adults in prednisolone-treated golden hamsters and Mongolian gerbils; the average recovery of cestodes of the SLI and JPN isolates were 55.8%-76.7% vs 11.7%-35.0% in the former and 28.0%-52.7% vs 25.8%-32.2% in the latter. The distinctly higher level of enteral establishment of the SLI isolate in golden hamsters makes available a model for quantitative studies on parasite-host relationships in experimental taeniasis.

This paper describes that the previous addition of Verapamil does not block the spastic response to Praziquantel (Pz) in larvae of Taenia pisiformis kept in vitro, where opposite results were found in the literature using mammalian tissue. It is possible that Pz stimulates other Ca++ transport channels not sensitive to Verapamil action and promotes Ca++ liberation from calcareous corpuscles stimulating phospholipase C of the tegument surface generating inositol triphosphate. These hypotheses require experimental approaches to define the exact mechanism of action.

Gossypol, a natural biphenyl compound inhibits Taenia taeniaeformis metacestode development in vivo. In this paper, the direct effect of gossypol on metacestodes was examined. Within 24 hr of incubation at 37 degrees C in greater than or equal to 10(-5) M gossypol, shedding of the tegument from the surface of the metacestodes was observed. There was a significant decrease in [3H]thymidine uptake by T. taeniaeformis in greater than or equal to 10(-5)M gossypol. In addition, NADH lactate dehydrogenase activity of metacestodes was significantly inhibited in greater than or equal to 10(-5) M gossypol. Thus, gossypol has a direct inhibitory effect on T. taeniaeformis metacestodes in vitro.

Five patients were studied who suffered secondary hydrocephalus due to neurocysticercosis. Shunt dysfunction was due to the obstruction of the ventricular catheter caused by the own cysticercus cysts. The Biomed system was used in four cases and the Hakim system in one. Valvular dysfunction was observed in patients within a period of 18 to 24 months after surgery, they had a history of several valvular dysfunctions. The diagnosis was made upon of extracting the catheter where the cyst was found to be attached to the ventricular brush. Subsequent evolution has not been satisfactory. The reasons for this complication are of a hydrodynamic and pharmacological nature and are also due to the growth of the cyst. This complication is not often suspected, therefore we recommend that in case of frequent valvular dysfunctions and asymmetrical hydrocephalus, studies like iodinetomography or magnetic resonance imaging be carried out in order to discard this possibility.