Performance characteristics of diagnostic assays for schistosomiasis in Ontario, Canada.

Introduction: Due to lower intensity of infection and greater intervals from last exposure, parasitologic detection methods for schistosomiasis are poorly sensitive in non-endemic areas, challenging accurate diagnosis. Methods: We evaluated parasitologic versus indirect detection methods for schistosomiasis. We included specimens submitted for Schistosoma serology, and stool for ova and parasite microscopy. Three real-time PCR assays targeting Schistosoma mansoni and S. haematobium were performed. Primary outcome measures were sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), where both microscopy and serology were the composite reference standard against serum PCR. Results: Of 8168 serum specimens submitted for Schistosoma serology, 638 (7.8%) were reactive and 6705 (82.1%) were non-reactive. Of 156,771 stool specimens submitted for ova and parasite testing, 46 (0.03%) were positive for eggs of S. mansoni. Four (0.5%) urine specimens were positive for eggs of S. haematobium. Combined serum PCRs targeting S. mansoni had a sensitivity and specificity of 27.8% (95% CI = 18.3-39.1%) and 100% (95% CI = 83.9-100%), respectively, with PPV of 100% (95% CI = 100%) and NPV of 26.9% (95% CI = 24.3-29.7%). The one serum sample positive for S. haematobium was also detectable by our S. haematobium PCR. No cross-reactivity was observed for all three PCR assays. Conclusions: Although serology is highly sensitive, parasitologic tests signify active infection, but are limited by low population-level sensitivity, particularly in non-endemic settings. Although serum PCR offered no performance advantage over stool microscopy, its role in diagnostic parasitology should be pursued due to its high-throughput and operator-independent nature.

TAU ablation in excitatory neurons and postnatal TAU knockdown reduce epilepsy, SUDEP, and autism behaviors in a Dravet syndrome model.

Intracellular accumulation of TAU aggregates is a hallmark of several neurodegenerative diseases. However, global genetic reduction of TAU is beneficial also in models of other brain disorders that lack such TAU pathology, suggesting a pathogenic role of nonaggregated TAU. Here, conditional ablation of TAU in excitatory, but not inhibitory, neurons reduced epilepsy, sudden unexpected death in epilepsy, overactivation of the phosphoinositide 3-kinase-AKT-mammalian target of rapamycin pathway, brain overgrowth (megalencephaly), and autism-like behaviors in a mouse model of Dravet syndrome, a severe epileptic encephalopathy of early childhood. Furthermore, treatment with a TAU-lowering antisense oligonucleotide, initiated on postnatal day 10, had similar therapeutic effects in this mouse model. Our findings suggest that excitatory neurons are the critical cell type in which TAU has to be reduced to counteract brain dysfunctions associated with Dravet syndrome and that overall cerebral TAU reduction could have similar benefits, even when initiated postnatally.

Molecular Surveillance for Imported Antimicrobial Resistant Plasmodium falciparum, Ontario, Canada.

Single-nucleotide polymorphisms at several loci have been correlated with Plasmodium falciparum drug resistance. We examined the prevalence of resistance markers in P. falciparum from imported malaria cases in Canada during 3 time periods, 2008-2009, 2013-2014, and 2017-2018. We evaluated single-nucleotide polymorphisms at atpase6 (pfATPase6), pfcrt (chloroquine resistance transporter), cytb (cytochrome b), dhfr (dihydrofolate reductase), dhps (dihydropteroate synthetase), mdr1 (multidrug resistance protein) and mdr1 copy number, and kelch13 (kelch protein gene on chromosome 13). Over time, we observed increasing mutant genotypes for dhfr S108N and dhps A613T and decreasing mutant genotypes for mdr1 N86Y, D1246Y, pfcrt K76T, and pfcrt 74-75; we identified no kelch13 mutations. We observed fewer mutations indicative of chloroquine resistance over time, which may reflect reduced chloroquine pressure in specimens from travelers to Africa. Mutations conferring proguanil resistance increased over time. Minor genotypes confirm the heterogeneous nature of infection and may affect treatment success.

Interdependence of neural network dysfunction and microglial alterations in Alzheimer's disease-related models.

Nonconvulsive epileptiform activity and microglial alterations have been detected in people with Alzheimer's disease (AD) and related mouse models. However, the relationship between these abnormalities remains to be elucidated. We suppressed epileptiform activity by treatment with the antiepileptic drug levetiracetam or by genetic ablation of tau and found that these interventions reversed or prevented aberrant microglial gene expression in brain tissues of aged human amyloid precursor protein transgenic mice, which simulate several key aspects of AD. The most robustly modulated genes included multiple factors previously implicated in AD pathogenesis, including TREM2, the hypofunction of which increases disease risk. Genetic reduction of TREM2 exacerbated epileptiform activity after mice were injected with kainate. We conclude that AD-related epileptiform activity markedly changes the molecular profile of microglia, inducing both maladaptive and adaptive alterations in their activities. Increased expression of TREM2 seems to support microglial activities that counteract this type of network dysfunction.

Evaluation of a point-of-care molecular detection device for Leishmania spp. and intercurrent fungal and mycobacterial organisms in Peruvian patients with cutaneous ulcers.

PURPOSE: Overlapping clinical features of cutaneous leishmaniasis (CL) with ulcers caused by fungi and mycobacteria necessitate confirmatory diagnostic testing. We evaluated a handheld battery-operated device for detection of CL and common fungal and mycobacterial causes of ulcers. METHODS: We validated Palm PCR™ for detection of common ulcerative skin pathogens using ATCC® reference and clinical strains of Leishmania, mycobacteria, and fungi in the lab and field. Amplified products were Sanger sequenced. Performance characteristics were calculated using conventional PCR as a reference standard. RESULTS: Palm PCR™ detected 100% of ATCC® strains of Leishmania, fungi, and mycobacteria, with sensitivity and specificity of 90% and 91.7%, respectively. In the field, the sensitivity for detection of Leishmania in patients with suspected CL was 100%. In 61% of CL patients, co-colonization with genera such as Malassezia, Aspergillus, Candida, and Cladosporium was detected. In 50% of CL patients with an inflammatory (secondarily infected) phenotype, detected fungal species had known associations with human cutaneous disease. CONCLUSIONS: Palm PCR™ performs comparably to conventional PCR for detection of Leishmania, fungi, and mycobacteria. This work has implications for the diagnostic approach to tropical ulcers, and has the potential to improve field detection of ulcerative pathogens in resource constrained areas.

Phenotypic Differences between the Alzheimer's Disease-Related hAPP-J20 Model and Heterozygous Zbtb20 Knock-Out Mice.

Diverse gene products contribute to the pathogenesis of Alzheimer's disease (AD). Experimental models have helped elucidate their mechanisms and impact on brain functions. Human amyloid precursor protein (hAPP) transgenic mice from line J20 (hAPP-J20 mice) are widely used to simulate key aspects of AD. However, they also carry an insertional mutation in noncoding sequence of one Zbtb20 allele, a gene involved in neural development. We demonstrate that heterozygous hAPP-J20 mice have reduced Zbtb20 expression in some AD-relevant brain regions, but not others, and that Zbtb20 levels are higher in hAPP-J20 mice than heterozygous Zbtb20 knock-out (Zbtb20+/-) mice. Whereas hAPP-J20 mice have premature mortality, severe deficits in learning and memory, other behavioral alterations, and prominent nonconvulsive epileptiform activity, Zbtb20+/- mice do not. Thus, the insertional mutation in hAPP-J20 mice does not ablate the affected Zbtb20 allele and is unlikely to account for the AD-like phenotype of this model.

Tau: Enabler of diverse brain disorders and target of rapidly evolving therapeutic strategies.

Several lines of evidence implicate the protein tau in the pathogenesis of multiple brain disorders, including Alzheimer's disease, other neurodegenerative conditions, autism, and epilepsy. Tau is abundant in neurons and interacts with microtubules, but its main functions in the brain remain to be defined. These functions may involve the regulation of signaling pathways relevant to diverse biological processes. Informative disease models have revealed a plethora of abnormal tau species and mechanisms that might contribute to neuronal dysfunction and loss, but the relative importance of their respective contributions is uncertain. This knowledge gap poses major obstacles to the development of truly impactful therapeutic strategies. The current expansion and intensification of efforts to translate mechanistic insights into tau-related therapeutics should address this issue and could deliver better treatments for a host of devastating conditions.