Balancing neuronal activity to fight neurodevelopmental disorders.

In a recent study, Rylaarsdam and colleagues revealed that mutant PACS1 gene, which causes a rare neurodevelopmental syndrome, affects the firing ability of human neurons without dysregulating the cellular architecture of brain organoids. These findings suggest aberrant neuronal electrophysiology as a possible interventional target for pediatric diseases impairing brain development.

High-content analysis of neuronal morphology in human iPSC-derived neurons.

We present a high-content analysis (HCA) protocol for monitoring the outgrowth capacity of human neurons derived from induced pluripotent stem cells (iPSCs). We describe steps to perform HCA imaging, followed by quantifying the morphology of dendrites and axons within a high-throughput system to evaluate neurons obtained through various differentiation approaches. This protocol can be used to screen for modulators of neuronal morphogenesis or neurotoxicity. The approach can be applied to patient-derived iPSCs to identify patient-specific defects and possible therapeutic strategies. For complete details on the use and execution of this protocol, please refer to Zink et al. (2020) and Inak et al. (2021). The protocol can be used in combination with Zink et al. (2022).

Tackling mitochondrial diversity in brain function: from animal models to human brain organoids.

Mitochondria exhibit high degree of heterogeneity within various tissues, including differences in terms of morphology, quantity, or function. Mitochondria can even vary among distinct sub-compartments of the same cell. Emerging evidence suggest that the molecular diversity of mitochondria can influence the identity and functionality of a given cell type. Human pathologies affecting mitochondria typically cause tissue and cell-type-specific impairment. Mitochondrial diversity could thus play a contributing role not only in physiological cell fate specification but also during pathological disease development. In this review, we discuss the role of mitochondrial diversity in brain function during health and disease. Recent advances in induced pluripotent stem cells (iPSCs) research and the derivation of cerebral organoids could provide novel opportunities to unveil the role of mitochondrial heterogeneity for the function of the human brain. Mitochondrial diversity might be at the bases of the cell-type-specific vulnerability of mitochondrial disorders and may represent an underappreciated target of disease intervention.

Seeking the reuse of effluents and sludge from conventional wastewater treatment plants: Analysis of the presence of intestinal protozoa and nematode eggs.

Some of the microorganisms present in urban wastewater, which include intestinal protozoa and nematodes, can be pathogenic. Their (oo)cyst and egg transmissible stages are very resistant to environmental stresses and disinfectants and they are therefore difficult to remove. Thus, they can constitute a health risk if water or sludge obtained in the purification of wastewater is reused for agricultural purposes. In this context, the presence of intestinal protozoa and nematodes were studied in influents, effluents and sludge from five wastewater treatment plants (WWTPs) in the north of Spain by optical microscopy and PCR techniques. The removal efficiency of different wastewater treatments was also compared. The presence of protozoa has increased among the population discharging waste to WWTPs in recent years. Cryptosporidium spp., Giardia duodenalis, Entamoeba spp. and nematodes were detected in all of the WWTPs. Indeed, this is the first report of Entamoeba histolytica and Entamoeba moshkovskii in Spanish WWTPs. The water treatments studied showed different removal efficiencies for each species of intestinal protozoa, with the aerated lagoons providing the best results. (Oo)cysts were also detected in sludge even after aerobic digestion and dehydration. To avoid risks, (oo)cyst viability should be analysed whenever the sludge is to be used as a fertilizer. This study reinforces the necessity of establishing legal limits on the presence of protozoa in WWTP effluents and sludges, especially if reuse is planned. Further studies are necessary for a better understanding of the presence and behaviour of intestinal parasites.

GSEA of mouse and human mitochondriomes reveals fatty acid oxidation in astrocytes.

The prevalent view in neuroenergetics is that glucose is the main brain fuel, with neurons being mostly oxidative and astrocytes glycolytic. Evidence supporting that astrocyte mitochondria are functional has been overlooked. Here we sought to determine what is unique about astrocyte mitochondria by performing unbiased statistical comparisons of the mitochondriome in astrocytes and neurons. Using MitoCarta, a compendium of mitochondrial proteins, together with transcriptomes of mouse neurons and astrocytes, we generated cell-specific databases of nuclear genes encoding for mitochondrion proteins, ranked according to relative expression. Standard and in-house Gene Set Enrichment Analyses (GSEA) of five mouse transcriptomes revealed that genes encoding for enzymes involved in fatty acid oxidation (FAO) and amino acid catabolism are consistently more expressed in astrocytes than in neurons. FAO and oxidative-metabolism-related genes are also up-regulated in human cortical astrocytes versus the whole cortex, and in adult astrocytes versus fetal astrocytes. We thus present the first evidence of FAO in human astrocytes. Further, as shown in vitro, FAO coexists with glycolysis in astrocytes and is inhibited by glutamate. Altogether, these analyses provide arguments against the glucose-centered view of energy metabolism in astrocytes and reveal mitochondria as specialized organelles in these cells.

Detección molecular de belactamasas de espectro extendido (BLEE) en enterobacterias aisladas en Asunción / Molecular detection of extended spectrum beta-lactamase (esbl) in enterobacteria isolated in Asunción

Las betalactamasas de espectro extendido (BLEE), son enzimas responsables de la hidrólisis del anillo betalactámico de penicilinas y cefalosporinas, excepto carbapemenes, inhibiendo así su actividad terapéutica. Si bien es posible la detección fenotípica de este mecanismo de resistencia por métodos convencionales, sólo los métodos moleculares permiten la identificación del gen responsable de dicha resistencia. El objetivo de este estudio descriptivo retrospectivo fue identificar los genes blaCTX-M2, blaPER-2, blaSHV y blaTEM, en aislamientos de enterobacterias productoras de BLEE,; de muestras clínicas colectadas entre julio 2007 y abril 2008, provenientes de dos hospitales de referencia de Asunción, Paraguay. La detección molecular de los genes se realizó por reacción en cadena de la polimerasa empleando oligonucleótidos específicos. De los 232 aislados BLEE analizados, el 83% (n=192) portó al menos un gen bla, en el 17% (n=40) restante no fue detectado ninguno de los genes incluido en el estudio. Se observaron las siguientes frecuencias: 49% (94/192) blaCTX-M2, 45% (86/192) blaSHV, 40% (77/192) blaTEM y 7% (13/192) blaPER-2. En el 47% (90/192) se detectó más de un gen, siendo la combinación blaCTX-M2+blaTEM+blaSHV, la más frecuente observada en 32 aislados. El blaCTX-M2 como el gen más frecuente en este estudio; concuerda con lo reportado en nuestro país y en Argentina. Este es el primer reporte de la presencia de blaTEM y blaSHV en Paraguay. Es de gran importancia el estudio de otros genes codificantes de resistencia, considerando la emergencia de otras BLEE en la región como blaCTX-M15 con actividad predominantemente ceftazidimasa.

Extended spectrum beta-lactamases (ESBLs), are enzymes responsible for thehydrolysis of the beta-lactam ring and resistance to both cephalosporins and penicillins,except carbapenems, therefore inhibiting its therapeutics activity. Even though, detectionof the phenotypic resistance mechanism by conventional methods is possible, onlymolecular methods allow identification of the gene responsible for the resistance. Theobjective of this retrospective study was to identify the blaCTX-M2, blaPER-2, blaSHV, blaTEMgenes in ESBL-producing enterobacteriaceae isolates, recovered from clinical samples collected between July 2007 and April 2008, from two reference hospitals in Asunción,Paraguay. Molecular gene detection was performed by polymerase chain reaction usingspecifics oligonucleotides. Out of the tested 232 ESBL-producing isolates, 83% (n=192)carried at least one of the bla genes as follows; 49% (94/192) blaCTX-M2, 45% (86/192)blaSHV, 40% (77/192) blaTEM and 7% (13/192) blaPER-2. In the rest 17% (n=40) none of thegenes included in this study was detected; in 47% (90/192) more than one gene wasdetected, resulting blaCTX-M2 + blaTEM + blaSHV as the most frequent combination in 32isolates. The presence of blaCTX-M2, as the most frequent codifying genes of BLEE is inagreement with previous reports in Paraguay and Argentina. This is the first report of thepresence of blaTEM and blaSHV circulating in Paraguay. It is of much importance the study ofothers codifying resistance genes, taking into account the emergence of other BLEE in theregion, such as blaCTX-M15, predominantly with ceftazidimase activity.

Síndrome diarreico agudo causado por Campylobacter spp. en pacientes menores de 11 años y su resistencia antimicrobiana a las drogas de elección para tratamiento 2010-2012, Paraguay / Acute Diarrhea Syndrome from Campylobacter spp. in Patients under Age 11 Years and Resistance to Drugs of Choice in Paraguay, 2010-2012

Objetivos: Determinar la prevalencia de Campylobacter spp. en pacientes menores de 11 años con síndrome diarreico agudo e indagar la resistencia antimicrobiana con respecto a las drogas de elección para el tratamiento clínico con Ciprofloxacina, Eritromicina y Tetraciclina. Materiales y Métodos: Se realizó un estudio descriptivo, retrospectivo de corte transverso, muestreo no probabilístico de casos consecutivos, cuya muestra tiene un tamaño de 1110 con un nivel de confianza de 95%. La población estudiada fue de pacientes pediátricos menores de 11 años cuyas muestras de heces fueron remitidas por las instituciones integrantes de la Red de Enteropatógenos al Laboratorio Central de Salud Pública en el periodo 2010-2012. Resultados: De 1110 muestras de heces estudiadas se aislaron Campylobacter spp. en 176 de ellas y corresponde al 16% de prevalencia. Se observó resistencia a las quinolonas en un 49 % de las muestras estudiadas, así como una resistencia a Tetraciclina del 28% y 1% de resistencia a los macrólidos (Eritromicina). Conclusión: Se observó una prevalencia importante de Campylobacter spp. como agente etiológico de síndrome diarreico agudo y es relevante la incorporación del aislamiento de este patógeno como agente etiológico rutinario en los análisis de coprocultivos realizados. La resistencia observada a las drogas de elección utilizadas como tratamiento nos obliga a tener en cuenta el control del uso indiscriminado de antimicrobianos

Molecular characterization of methicillin-resistant Staphylococcus aureus isolates collected in Asunción, Paraguay.

We characterized 34 methicillin-resistant Staphylococcus aureus strains isolated in Paraguay in 2005. The strains belonged to two clones. The major clone (sequence type 5 [ST5] or ST221, spa type t149, staphylococcal cassette chromosome mec [SCCmec] type I) was similar to the Cordobes/Chilean clone spreading through South America, and the minor clone (ST239 or ST889, spa type t037, SCCmec type IIIA) was related to the Brazilian clone.