The impact of the COVID-19 pandemic on source plasma donations.

While the COVID-19 pandemic has impacted many aspects of healthcare, including routine blood donations, the impact of COVID-19 on the donation of source plasma critical to many aspects of patient care, including apheresis procedures, has been more difficult to define. As production of plasma-derived medicinal products (PDMPs) can take up to a year, shortages in source plasma donations may not be immediately appreciated. Given current shortages in PDMPs, in particular albumin, we examined the impact of COVID-19 on source plasma donations. Our data demonstrate that source plasma donations were disproportionately impacted by COVID-19 and that these shortages remained until the latter half of 2022. Given the time delay in PDMP manufacturing, these results suggest that while source plasma donation levels are returning to pre-pandemic levels, shortages in PDMPs may not be quickly overcome. These results also highlight the unique vulnerabilities in plasma sourcing that may continue to manifest as PDMP shortages for years to come.

Analysis, detection and quantitation of mixed cryoglobulins in HCV infection: brief review and case examples.

Considering the high incidence of cryoglobulins in hepatitis C virus (HCV) infection together with the high worldwide prevalence of HCV infection, identification of clinically apparent mixed cryoglobulinemia syndrome is increasingly important as most patients who are identified can now be successfully treated. Different approaches for the detection, analysis and reporting of cryoglobulins have been described and there is a wide variation in results reported, ranging from a qualitative "negative" or "positive", to a quantitative report including cryoglobulin type and the total protein. Protein and immunofixation (IFE) electrophoresis are generally used to identify and characterize cryoglobulins, as these methods quantify and phenotype. Here, we present a brief review of the literature and demonstrate a case oriented approach for identifying mixed cryoglobulinemia from the preanalytical phase, leading up to and including the analytical phase with characterization by IFE. Most patients with mixed cryoglobulinemia can now be treated with success. Nevertheless, the high cost may limit treatment of those with symptoms unless there is laboratory evidence for mixed cryoglubulinemia. Low levels of cryoglobulins can be associated with severe symptoms; as a result, accurate identification of cryoglobulins may be of increasing importance since clear identification may be a good reason to initiate treatment.

Reduced cellular Mg²âº content enhances hexose 6-phosphate dehydrogenase activity and expression in HepG2 and HL-60 cells.

We have reported that Mg(2+) dynamically regulates glucose 6-phosphate entry into the endoplasmic reticulum and its hydrolysis by the glucose 6-phosphatase in liver cells. In the present study, we report that by modulating glucose 6-phosphate entry into the endoplasmic reticulum of HepG2 cells, Mg(2+) also regulates the oxidation of this substrate via hexose 6-phosphate dehydrogenase (H6PD). This regulatory effect is dynamic as glucose 6-phosphate entry and oxidation can be rapidly down-regulated by the addition of exogenous Mg(2+). In addition, HepG2 cells growing in low Mg(2+) show a marked increase in hexose 6-phosphate dehydrogenase mRNA and protein expression. Metabolically, these effects on hexose 6-phosphate dehydrogenase are important as this enzyme increases intra-reticular NADPH production, which favors fatty acid and cholesterol synthesis. Similar effects of Mg(2+) were observed in HL-60 cells. These and previously published results suggest that in an hepatocyte culture model changes in cytoplasmic Mg(2+) content regulates glucose 6-phosphate utilization via glucose 6 phosphatase and hexose-6 phosphate dehydrogenase in alternative to glycolysis and glycogen synthesis. This alternative regulation might be of relevance in the transition from fed to fasted state.

Low Hepatic Mg2+ Content promotes Liver dysmetabolism: Implications for the Metabolic Syndrome.

Metabolic Syndrome, a pathological condition affecting approximately 35% of the USA population, is characterized by obesity, insulin resistance, and hypertension. Metabolic syndrome is considered the single most common condition predisposing to the development of various chronic diseases including diabetes and hypertension. Hypomagnesaemia has been consistently observed in association with metabolic syndrome, but it is unclear whether reduced Mg2+ levels are the consequence or a possible cause for the development of the metabolic syndrome and/or its associated pathologies. Research performed in our laboratory showed that rats exposed for 2 weeks to a Mg2+ deficient diet presented decreased glucose accumulation into the hepatocytes together with low Mg2+ level in the circulation and within the liver cells. To better investigate the changes in glucose metabolism, HepG2 were used to mimic in vitro Mg2+ deficiency conditions. HepG2 cells cultured in low extracellular Mg2+ presented a 20% decrease in total cellular Mg2+ content, reduced glucose accumulation, and enhanced glucose 6-phosphate (G6P) transport into the endoplasmic reticulum (ER). The increased G6P transport was associated with its enhanced hydrolysis by the glucose 6-phosphatase, but also conversion to 6-phosphogluconolactone by the glucose 6-phosphate dehydrogenase. The latter process resulted in the increased generation of NADPH within the ER and the increased conversion of cortisone to cortisol by the 11-ß-hydroxysteroid dehydrogenase type-1 (11-ß-OHSD1). Taken together, our results provide compelling evidence that Mg2+ deficiency precedes and actually promotes some of the hepatic dysmetabolisms typical of the metabolic syndrome. The decrease in intrahepatic Mg2+ content up-regulates G6P entry into the hepatic endoplasmic reticulum and its routing into the pentose shunt pathway for energetic purposes. The associated increased in NADPH production within the ER then stimulates cortisol production, setting the conditions for hepatic insulin resistance and further altering liver metabolism.

Characterization of spontaneously generated prion-like conformers in cultured cells.

A distinct conformational transition from the α-helix-rich cellular prion protein (PrPC) into its ß-sheet-rich pathological isoform (PrPSc) is the hallmark of prion diseases, a group of fatal transmissible encephalopathies that includes spontaneous and acquired forms. Recently, a PrPSc-like intermediate form characterized by the formation of insoluble aggregates and protease-resistant PrP species termed insoluble PrPC (iPrPC) has been identified in uninfected mammalian brains and cultured neuronal cells, providing new insights into the molecular mechanism(s) of these diseases. Here, we explore the molecular characteristics of the spontaneously formed iPrPC in cultured neuroblastoma cells expressing wild-type or mutant human PrP linked to two familial prion diseases. We observed that although PrP mutation at either residue 183 from Thr to Ala (PrPT183A) or at residue 198 from Phe to Ser (PrPF198S) affects glycosylation at both N-linked glycosylation sites, the T183A mutation that results in intracellular retention significantly increased the formation of iPrPC. Moreover, while autophagy is increased in F198S cells, it was significantly decreased in T183A cells. Our results indicate that iPrPC may be formed more readily in an intracellular compartment and that a significant increase in PrPT183A aggregation may be attributable to the inhibition of autophagy.