Covid-19 automated diagnosis and risk assessment through Metabolomics and Machine-Learning

COVID-19 is still placing a heavy health and financial burden worldwide. Impairments in patient screening and risk management play a fundamental role on how governments and authorities are directing resources, planning reopening, as well as sanitary countermeasures, especially in regions where poverty is a major component in the equation. An efficient diagnostic method must be highly accurate, while having a cost-effective profile. We combined a machine learning-based algorithm with instrumental analysis using mass spectrometry to create an expeditious platform that discriminate COVID-19 in plasma samples within minutes, while also providing tools for risk assessment, to assist healthcare professionals in patient management and decision-making. A cross-sectional study with 728 patients (369 confirmed COVID-19 and 359 controls) was enrolled from three Brazilian epicentres (Sao Paulo capital, Sao Paulo countryside and Manaus) in the months of April, May, June and July 2020. We were able to elect and identify 21 molecules that are related to the diseases pathophysiology and 26 features to patients health-related outcomes. With specificity >97% and sensitivity >83% from blinded data, this screening approach is understood as a tool with great potential for real-world application.

mRNA and protein expression and activities of nitric oxide synthases in the lumbar spinal cord of neonatal rats after sciatic nerve transection and melatonin administration.

Sciatic axotomy in 2-day-old rats (P2) causes lumbar motoneuron loss, which could be associated with nitric oxide (NO) production. NO may be produced by three isoforms of synthase (NOS): neuronal (nNOS), endothelial (eNOS) and inducible (iNOS). We investigated NOS expression and NO synthesis in the lumbar enlargement of rats after sciatic nerve transection at P2 and treatment with the antioxidant melatonin (sc; 1 mg/kg). At time points ranging from P2 to P7, expression of each isoform was assessed by RT-PCR and immunohistochemistry; catalytic rates of calcium-dependent (nNOS, eNOS) and independent (iNOS) NOS were measured by the conversion of [3H]L-arginine to [3H]L-citrulline. All NOS isoforms were expressed and active in unlesioned animals. nNOS and iNOS were detected in some small cells in the parenchyma. Only endothelial cells were positive for eNOS. No NOS isoform was detected in motoneurons. Axotomy did not change these immunohistochemical findings, nNOS and iNOS mRNA expression and calcium-independent activity at all survival times. However, sciatic nerve transection reduced eNOS mRNA levels at P7 and increased calcium-dependent activity at 1 and 6 h. Melatonin did not alter NOS expression. Despite having no action on NOS activity in unlesioned controls the neurohormone enhanced calcium-dependent activity at 1 and 72 h and reduced calcium-independent catalysis at 72 h in lesioned rats. These results suggest that NOS isoforms are constitutive in the neonatal lumbar enlargement and are not overexpressed after sciatic axotomy. Changes in NO synthesis induced by axotomy and melatonin administration in the current model are discussed considering some beneficial and deleterious effects that NO may have.

Bax and Bcl-2 expression and TUNEL labeling in lumbar enlargement of neonatal rats after sciatic axotomy and melatonin treatment.

Peripheral axotomy in neonatal rats induces neuronal death. We studied the anti-apoptotic protein Bcl-2 and cell death promoter Bax in spinal cord of neonatal rats after sciatic transection and treatment with melatonin, a neuroprotective substance. Pups were unilaterally axotomized at P2 and received melatonin (1 mg/kg; sc) or vehicle 1 h prior to lesion, immediately after, at 1 h, 2 h and then once daily. Rats were sacrificed at 3 h, 6 h, 24 h, 72 h and 5 days postaxotomy. Intact animals were used as controls. Lumbar enlargement was processed for Nissl staining, immunohistochemistry and RT-PCR for Bax or Bcl-2 and TUNEL reaction. Motoneurons (MN) of lesioned (L) and normal (N) sides were counted, and MN survival ratio (MSR=L/N) was calculated. Bax and Bcl-2 showed cytoplasmic immunoreactivity (IR). Bax IR was noticeable in small cells but less evident in MN. In unlesioned pups, some Bax-positive small cells (B+) and TUNEL-positive nuclei (T+) were mainly seen in the dorsal horn. In lesioned animals given vehicle, Bax mRNA levels and numbers of B+ and T+ were increased in comparison with intact controls at 24 h postaxotomy. The basal IR for Bax in MN was not changed by axotomy. Bcl-2 IR was noted in all cells and, like Bcl-2 mRNA, was unaltered after lesion. Melatonin reduced MN loss at 24 h, 72 h and 5 days and T+ at 24 h after lesion but did not interfere with Bax or Bcl-2 expression. These results suggest that (1) sciatic transection at P2 increases Bax mRNA and the amount of B+ and T+ in the lumbar enlargement, (2) Bax IR in immature MN is not altered by axotomy and (3) melatonin protects MN and dorsal horn cells through a mechanism independent of Bax and Bcl-2.