SARS-CoV-2 Spike Protein Binding of Glycated Serum Albumin—Its Potential Role in the Pathogenesis of the COVID-19 Clinical Syndromes and Bias towards Individuals with Pre-Diabetes/Type 2 Diabetes and Metabolic Diseases

The immune response to SARS-CoV-2 infection requires antibody recognition of the spike protein. In a study designed to examine the molecular features of anti-spike and anti-nucleocapsid antibodies, patient plasma proteins binding to pre-fusion stabilised complete spike and nucleocapsid proteins were isolated and analysed by matrix-assisted laser desorption ionisation–time of flight (MALDI-ToF) mass spectrometry. Amongst the immunoglobulins, a high affinity for human serum albumin was evident in the anti-spike preparations. Careful mass comparison revealed the preferential capture of advanced glycation end product (AGE) forms of glycated human serum albumin by the pre-fusion spike protein. The ability of bacteria and viruses to surround themselves with serum proteins is a recognised immune evasion and pathogenic process. The preference of SARS-CoV-2 for AGE forms of glycated serum albumin may in part explain the severity and pathology of acute respiratory distress and the bias towards the elderly and those with (pre)diabetic and atherosclerotic/metabolic disease.     

Formation of biogenic amines in herring and mackerel

The formation of biogenic amines (histamine, cadaverine, putrescine and spermidine) was followed during vacuum packed storage at 2 degrees C or 10 degrees C in the scombroid fish mackerel and in the non-scombroid fish herring. Also the changes in the content of free amino acids and in the organoleptic and microbiological qualities were followed. At 10 degrees C the amine contents were 2-20 times higher at the time of rejection as compared with samples stored at 2 degrees C. In herring and mackerel similar amounts of histamine were accumulated, whilst cadaverine was formed at much higher levels in mackerel compared with herring. The high contents of cadaverine in mackerel can possibly explain why mackerel and not herring are often implicated in incidents of scombrotoxic poisoning.     

Rheological properties and stability of model salad dressing emulsions prepared with a dry-heated soybean protein isolate–dextran mixture

The rheological characteristics of model salad dressing emulsions, incorporating a dry-heated soybean protein isolate (SPI)–dextran mixture as emulsifier, were investigated by applying dynamic rheometry tests in an attempt to probe the emulsion structure and to elucidate the mechanism of their stability against creaming. Both the viscoelastic properties and the creaming behaviour of the dressings were greatly influenced by the extent of protein–dextran conjugation and also by xanthan gum addition. The results are discussed in terms of emulsion droplet interactions which, depending on the extent of glyco-conjugation, may be dominated by depletion or ‘bridging’ flocculation effects and, thereby, influence the droplet network structure collapse during ageing.     

Contribution of extracellular polymeric substances from Shewanella sp. HRCR-1 biofilms to U(VI) immobilization

The goal of this study was to quantify the contribution of extracellular polymeric substances (EPS) to U(VI) immobilization by Shewanella sp. HRCR-1. Through comparison of U(VI) immobilization using cells with bound EPS (bEPS) and cells with minimal EPS, we show that (i) bEPS from Shewanella sp. HRCR-1 biofilms contribute significantly to U(VI) immobilization, especially at low initial U(VI) concentrations, through both sorption and reduction; (ii) bEPS can be considered a functional extension of the cells for U(VI) immobilization and they likely play more important roles at lower initial U(VI) concentrations; and (iii) the U(VI) reduction efficiency is dependent upon the initial U(VI) concentration and decreases at lower concentrations. To quantify the relative contributions of sorption and reduction to U(VI) immobilization by EPS fractions, we isolated loosely associated EPS (laEPS) and bEPS from Shewanella sp. HRCR-1 biofilms grown in a hollow fiber membrane biofilm reactor and tested their reactivity with U(VI). We found that, when reduced, the isolated cell-free EPS fractions could reduce U(VI). Polysaccharides in the EPS likely contributed to U(VI) sorption and dominated the reactivity of laEPS, while redox active components (e.g., outer membrane c-type cytochromes), especially in bEPS, possibly facilitated U(VI) reduction.     

Modelling of acidification kinetics and textural properties in dahi (Indian yogurt) made from buffalo milk using response surface methodology

The simultaneous effects of fermentation temperature (20.8–29.2C), total solids (TS) level (13–16% w/v) and total inoculum level (1–4% v/v) on the acidification process in buffalo milk fermented with dahi culture were explored by means of response surface methodology. The changes in lactose content and lactic acid in buffalo milk (14.5% TS) inoculated with 2.5% culture were investigated during fermentation at 27.5C. The utilization of lactose followed first order kinetics during dahi fermentation. The syneresis increased with increase in fermentation temperatures. A firmer gel was achieved with a medium acidification rate in the range of fermentation temperatures from 27C to 29.2C, medium TS of 14.5–15%, and at a total inoculum level of 2.5%.     

Isolation of monoclonal antibodies monospecific for bovine alpha-lactalbumin.

Monoclonal antibodies were generated against purified bovine alpha-lactalbumin. Three antibodies reactive only to alpha-lactalbumin were selected. Two of the antibodies appeared to be species monospecific and bound with only bovine alpha-lactalbumin. The third monoclonal recognized both bovine and human alpha-lactalbumin with a 2:1 preference for bovine alpha-lactalbumin. Two of the monoclonals (48-60, 48-68) bound to different epitopes with high affinity (Ka = 8 x 10(11), 5.3 x 10(12) M-1). The third monoclonal (48-22), which was of isotype IgA, had an epitope similar to that of 48-60 but with an apparent affinity of approximately 4 x 10(12) M-1. These antibodies should prove extremely useful adjuncts in structural studies of bovine alpha-lactalbumin.