Hydrogen sulfide (H₂S) concentration can be maintained in cell cultures within the range reported for rat brain by repetitive pulses of sodium hydrogen sulfide. Less than 2 h exposure to H₂S concentrations within 50 and 120 μM (i.e., within the upper segment of the reported physiological range of H₂S in rat brain), produces a large shift of the intracellular calcium homeostasis in cerebellar granule neurons (CGN) in culture, leading to a large and sustained increase of cytosolic calcium concentration. Only 1 h exposure to H₂S concentrations within 100 and 300 μM raises intracellular calcium to the neurotoxic range, with nearly 50% cell death after 2 h. L-type Ca²⁺ channels antagonists nimodipine and nifedipine block both the H₂S-induced rise of cytosolic calcium and cell death. The N-methyl-D-aspartate receptor antagonists (+)-MK-801 and DL-2-amino-5-phosphonovaleric acid afforded a nearly complete protection against H₂S-induced CGN death and largely attenuated the rise of cytosolic calcium. Thus, H₂S-induced rise of cytosolic calcium eventually reaches the neurotoxic cytosolic calcium range, leading to glutamate-induced excitotoxic CGN death. The authors conclude that H₂S is a major modulator of calcium homeostasis in neurons as it induces activation of Ca²⁺ entry through L-type Ca²⁺ channels, and thereby of neuronal activity.

Highly pathogenic avian influenza viruses (HPAIVs) are a permanent threat to public health due to their potential zoonotic transmission. Among HPAIVs, Influenza A H5 viruses have caused outbreaks in poultry and wild birds worldwide, ¹ and virus clade 2.3.4.4b outbreaks have been reported in Europe, Asia, Africa and North America since 2020, accounting for an unprecedented number of bird deaths. ² The mutation ability to infect new species, including humans, makes HPAIVs of high concern. ^3–5 Since 2020, six human cases of clade 2.3.4.4b viruses have been reported to WHO from China, Spain, UK, USA and Vietnam. ⁶ During late 2022, H5N1 outbreaks were declared in South America and clade 2.3.4.4b was identified for the first time in the region. ^{6, 7}

Background: Multiple RT-qPCR kits are available in the market for SARS-CoV-2 diagnosis, some of them with Emergency Use Authorization (EUA) by FDA or their country of origin agency, but many of them lack of proper clinical evaluation. Objective: We evaluated the clinical performance of two Korean SARS-CoV-2 RT-PCR kits available in South America, AccuPower SARS-CoV-2 Multiplex RT-PCR kit (Bioneer, South Korea) and Allplex 2019-nCoV Assay (Seegene, South Korea), for RT-qPCR SARS-CoV-2 diagnosis using the CDC protocol as a gold standard. Results: We found strong differences among both kits clinical performance and analytical sensitivity; while the Allplex 2019-nCoV Assay has sensitivity of 96.5% and an estimated limit of detection of 4,000 copies/ml, the AccuPower SARS-CoV-2 Multiplex RT-PCR kit has a sensitivity of 75.5% and limit of detection estimated to be bigger than 20,000 copies/ml. Conclusions: AccuPower SARS-CoV-2 Multiplex RT-PCR kit and Allplex 2019-nCoV Assay are both made in South Korea but EUA by Korean CDC was only granted to the later. Our results support that Korean CDC EUA should be considered as a quality control proxy for Korean SARS-CoV-2 RT-PCR kits prior to importation by developing countries to guarantee high sensitivity diagnosis.