Phosphate-activated glutaminase activity is enhanced in brain, intestine and kidneys of rats following portacaval anastomosis

AIM: To assess whether portacaval anastomosis (PCA) in rats affects the protein expression and/or activity of glutaminase in kidneys, intestines and in three brain areas of cortex, basal ganglia and cerebellum and to explain the neurological alterations found in hepatic encephalopathy (HE). METHODS: Sixteen male Wistar rats weighing 250-350 gwere grouped into sham-operation control (n = 8) or portacaval shunt (n = 8). Twenty-eight days after the procedure, the animals were sacrificed. The duodenum, kidney and brain were removed, homogenised and mitochondria were isolated. Ammonia was measured in brain and blood. Phosphate-activated glutaminase (PAG) activity was determined by measuring ammonia production following incubation for one hour at 37 with O-phthalaldehyde (OPA) and specific activity expressed in units per gram of protein (μkat/g of protein). Protein expression was measured by immunoblotting. RESULTS: Duodenal and kidney PAG activities together with protein content were significantly higher in PCA group than in control or sham-operated rats (duodenum PAG activity was 976.95±268.87 μkat/g of protein in PCA rats vs 429.19±126.92 μkat/g of protein in shamoperated rats; kidneys PAG activity was 1259.18 ± 228.79 μkat/g protein in PCA rats vs 669.67± 400.8 μkat/g of protein in controls, P < 0.05; duodenal protein content: 173% in PCA vs sham-operated rats; in kidneys the content of protein was 152% in PCA vs sham-operated rats). PAG activity and protein expression in PCA rats were higher in cortex and basal ganglia than those in shamoperated rats (cortex: 6646.6 ± 1870.4 μkat/g of protein vs 3573.8 ± 2037.4 μkat/g of protein in control rats, P < 0.01; basal ganglia, PAG activity was 3657.3 ± 1469.6 μkat/g of protein in PCA rats vs 2271.2 ± 384 μkat/g of protein in sham operated rats, P < 0.05; In the cerebellum, the PAG activity was 2471.6 ± 701.4 μkat/g of protein vs 1452.9 ± 567.8 μkat/g of protein in the PCA and sham rats, respectively, P < 0.05; content of protein:cerebral cortex: 162% ± 40% vs 100% ± 26%, P < 0.009;and basal gangl ia: 140% ± 39% vs 100% ± 14%,P < 0.05; but not in cerebel lum: 100% ± 25% vs 100% ± 16%, P = ns). CONCLUSION: Increased PAG activity in kidney and duodenum could contribute significantly to the hyperammonaemia in PCA rats, animal model of encephalopathy. PAG is increased in non-synaptic mitochondria from the cortex and basal ganglia and could be implicated in the pathogenesis of hepatic encephalopathy. Therefore, PAG could be a possible target for the treatment of HE orliver dysfunction

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality