Pharmacodynamics of ATI-2307 in a rabbit model of cryptococcal meningoencephalitis.

Cryptococcal meningoencephalitis (CM) is a devastating fungal disease with high morbidity and mortality. The current regimen that is standard-of-care involves a combination of three different drugs administered for up to one year. There is a critical need for new therapies due to both toxicity and inadequate fungicidal activity of the currently available antifungal drugs. ATI-2307 is a novel aryl amidine that disrupts the mitochondrial membrane potential and inhibits the respiratory chain complexes of fungi-it thus represents a new mechanism for direct antifungal action. Furthermore, ATI-2307 selectively targets fungal mitochondria via a fungal-specific transporter that is not present in mammalian cells. It has very potent in vitro anticryptococcal activity. In this study, the efficacy of ATI-2307 was tested in a rabbit model of CM. ATI-2307 demonstrated significant fungicidal activity at dosages between 1 and 2 mg/kg/d, and these results were superior to fluconazole and similar to amphotericin B treatment. When ATI-2307 was combined with fluconazole, the antifungal effect was greater than either therapy alone. While ATI-2307 has potent anticryptococcal activity in the subarachnoid space, its ability to reduce yeasts in the brain parenchyma was relatively less over the same study period. This new drug, with its unique mechanism of fungicidal action and ability to positively interact with an azole, has demonstrated sufficient anticryptococcal potential in this experimental setting to be further evaluated in clinical studies.

The identification of dual protective agents against cisplatin-induced oto- and nephrotoxicity using the zebrafish model.

Dose-limiting toxicities for cisplatin administration, including ototoxicity and nephrotoxicity, impact the clinical utility of this effective chemotherapy agent and lead to lifelong complications, particularly in pediatric cancer survivors. Using a two-pronged drug screen employing the zebrafish lateral line as an in vivo readout for ototoxicity and kidney cell-based nephrotoxicity assay, we screened 1280 compounds and identified 22 that were both oto- and nephroprotective. Of these, dopamine and L-mimosine, a plant-based amino acid active in the dopamine pathway, were further investigated. Dopamine and L-mimosine protected the hair cells in the zebrafish otic vesicle from cisplatin-induced damage and preserved zebrafish larval glomerular filtration. Importantly, these compounds did not abrogate the cytotoxic effects of cisplatin on human cancer cells. This study provides insights into the mechanisms underlying cisplatin-induced oto- and nephrotoxicity and compelling preclinical evidence for the potential utility of dopamine and L-mimosine in the safer administration of cisplatin.

hace1 Influences zebrafish cardiac development via ROS-dependent mechanisms.

BACKGROUND: In this study, we reveal a previously undescribed role of the HACE1 (HECT domain and Ankyrin repeat Containing E3 ubiquitin-protein ligase 1) tumor suppressor protein in normal vertebrate heart development using the zebrafish (Danio rerio) model. We examined the link between the cardiac phenotypes associated with hace1 loss of function to the expression of the Rho small family GTPase, rac1, which is a known target of HACE1 and promotes ROS production via its interaction with NADPH oxidase holoenzymes. RESULTS: We demonstrate that loss of hace1 in zebrafish via morpholino knockdown results in cardiac deformities, specifically a looping defect, where the heart is either tubular or "inverted". Whole-mount in situ hybridization of cardiac markers shows distinct abnormalities in ventricular morphology and atrioventricular valve formation in the hearts of these morphants, as well as increased expression of rac1. Importantly, this phenotype appears to be directly related to Nox enzyme-dependent ROS production, as both genetic inhibition by nox1 and nox2 morpholinos or pharmacologic rescue using ROS scavenging agents restores normal cardiac structure. CONCLUSIONS: Our study demonstrates that HACE1 is critical in the normal development and proper function of the vertebrate heart via a ROS-dependent mechanism. Developmental Dynamics 247:289-303, 2018. © 2017 Wiley Periodicals, Inc.

Enzalutamide inhibits testosterone-induced growth of human prostate cancer xenografts in zebrafish and can induce bradycardia.

The zebrafish has become a popular human tumour xenograft model, particularly for solid tumours including prostate cancer (PCa). To date PCa xenotransplantation studies in zebrafish have not been performed in the presence of testosterone, even when employing androgen-dependent cell models, such as the LNCaP cell line. Thus, with the goal of more faithfully modelling the hormonal milieu in which PCa develops in humans, we sought to determine the effects of exogenous testosterone on the growth of LNCaP, or androgen-independent C4-2 cells xenografted into zebrafish embryos. Testosterone significantly increased engrafted LNCaP proliferation compared to control xenografts, which could be inhibited by co-administration of the anti-androgen receptor drug, enzalutamide. By contrast, C4-2 cell growth was not affected by either testosterone or enzalutamide. Enzalutamide also induced bradycardia and death in zebrafish embryos in a dose-dependent manner and strongly synergized with the potassium-channel blocking agent, terfenadine, known to induce long QT syndrome and cardiac arrhythmia. Together, these data not only indicate that testosterone administration should be considered in all PCa xenograft studies in zebrafish but also highlights the unique opportunity of this preclinical platform to simultaneously evaluate efficacy and toxicity of novel therapies and/or protective agents towards developing safer and more effective PCa treatments.

Environmental Persistence and Infectivity of Oocysts of Two Species of Gregarines, Blabericola migrator and Blabericola cubensis (Apicomplexa: Eugregarinida: Blabericolidae), Parasitizing Blaberid Cockroaches (Dictyoptera: Blaberidae).

For apicomplexan parasites using an oral-fecal transmission route with significant environmental exposure, the environmental persistence and infectivity of the oocyst has a direct impact on local infection dynamics, including the ability to withstand extended periods without readily available hosts. Herein we quantify the environmental persistence and infectivity of the oocysts of 2 septate gregarine species at controlled temperature and humidity and demonstrate that they can persist over multiple generational time spans. Species of Blabericola generally complete their endogenous life cycles from oocyst to oocyst within 10 days. The median residual environmental oocyst lifetime for Blabericola oocysts in this study is 21-28 days, but a significant number of oocysts of Blabericola migrator persisted and remained infective in the environment for up to 39 days while those of Blabericola cubensis persisted and remained infective for up to 92 days. Although long-lived relative to their own generational time, the oocysts of Blabericola species infecting cockroaches are short-lived relative to gregarines infecting tenebrionid beetles. For these gregarines, oocysts can persist in the environment and remain infective for up to 787 days. Mechanistically, environmental persistence and infectivity are probably energy-limited phenomena related to the amount of stored amylopectin and the basal metabolic rate of quiescent oocysts.

Excystation signals do not isolate gregarine gene pools: experimental excystation of Blabericola migrator among 11 species of cockroaches.

An experimental excystation assay was used to test the potential species isolating effects of excystation signaling among gregarines. Oocysts of a single gregarine species, Blabericola migrator , were tested for activation, excystation, and sporozoite motility by using intestinal extracts from 11 species of cockroaches representing a cohesive phylogeny of 7 genera, 3 subfamilies, and 2 families of Blattodea. Sporozoite activation, excystation, and motility were observed for all excystation assay replications using intestinal fluid from blaberid hosts, but delayed activation or excystation was observed for all assay replications using intestinal fluid from hosts in the family Blattidae. The results illustrate a trend toward a generalized excystation signal among gregarines that is conserved across the host clade at a subfamily or family level but that is unlikely to play a significant role as a species-isolating mechanism among sibling gregarine species.

Pheochromocytoma in a white rhinoceros (Ceratotherium simum).

A 46-yr-old male white rhinoceros (Ceratotherium simum) died during anesthesia following agonal excitation. On postmortem, a well-demarcated 2.5-cm tan mass was identified in the right adrenal gland. Histopathology confirmed the presence of a pheochromocytoma, and elevated levels of epinephrine in serum collected shortly prior to the animal's death, as compared with sera from healthy controls, demonstrated the functional nature of the tumor. Although rare, pheochromocytoma should be considered as a differential diagnosis in cases of suspected hypertension and acute death in rhinos.