Platelets mediate the clearance of senescent red blood cells by forming prophagocytic platelet-cell complexes.

ABSTRACT: In humans, ∼0.1% to 0.3% of circulating red blood cells (RBCs) are present as platelet-RBC (P-RBC) complexes, and it is 1% to 2% in mice. Excessive P-RBC complexes are found in diseases that compromise RBC health (eg, sickle cell disease and malaria) and contribute to pathogenesis. However, the physiological role of P-RBC complexes in healthy blood is unknown. As a result of damage accumulated over their lifetime, RBCs nearing senescence exhibit physiological and molecular changes akin to those in platelet-binding RBCs in sickle cell disease and malaria. Therefore, we hypothesized that RBCs nearing senescence are targets for platelet binding and P-RBC formation. Confirming this hypothesis, pulse-chase labeling studies in mice revealed an approximately tenfold increase in P-RBC complexes in the most chronologically aged RBC population compared with younger cells. When reintroduced into mice, these complexes were selectively cleared from the bloodstream (in preference to platelet-free RBC) through the reticuloendothelial system and erythrophagocytes in the spleen. As a corollary, patients without a spleen had higher levels of complexes in their bloodstream. When the platelet supply was artificially reduced in mice, fewer RBC complexes were formed, fewer erythrophagocytes were generated, and more senescent RBCs remained in circulation. Similar imbalances in complex levels and senescent RBC burden were observed in humans with immune thrombocytopenia (ITP). These findings indicate that platelets are important for binding and clearing senescent RBCs, and disruptions in platelet count or complex formation and clearance may negatively affect RBC homeostasis and may contribute to the known risk of thrombosis in ITP and after splenectomy.

Oral perception of the textural and flavor characteristics of soy-cow blended emulsions.

Soy-cow blended milk is a potential nutritional beverage and raw material for dairy products. This study determined the particle size, flow, lubrication, flavor and sensory properties of cow milk, soy milk and their blends. Twenty-one major volatile compounds were identified using solid-phase microextraction gas chromatography (SPME-GCMS) in cow milk and soy milk. Among all the compounds detected in the milk samples, hexanal, associated with off flavor was found highest in soymilk followed by cow milk and blended milk. From confocal images, soy-cow blended milk at a ratio of 1:1 showed a homogenous distribution of small fat globules and protein compared to the soy milk and cow milk. The addition of soy milk to cow milk lowers the particle size although not significantly (p > .05) and decreases the viscosity of blended milk. Cow milk was the most viscous (2.66 mPa·s at 50 s-1 ) with large particles (0.48 µm) observed from confocal images. However, soymilk was found to have better lubrication properties (boundary regime) with a lower friction coefficient (~0.30) compared to cow milk (~0.40) and blended milk (~0.50) at low entrainment speed (0.1-2 mm/s). The sensory panel ranked cow milk as creamier and more viscous while soymilk was perceived as more astringent with beany flavor. Overall, a proportion of 3:7 soy-cow blended milk was more acceptable than the other two blended milks with less beany flavor, as confirmed by the lower amount of hexanal from gas chromatography mass spectrometer.

Bioconversion and bioaccessibility of isoflavones from sogurt during in vitro digestion.

This study investigated the bioconversion and bioaccessibility of soy isoflavones produced in sogurt fermented with S. thermophilus and L. bulgaricus during in vitro digestion. The highest survivability of S. thermophilus (6.49 log cfu/mL) and L. bulgaricus (6.48 log cfu/mL) was in oral phase. In gastric phase, the total aglycones of sogurt (26.73 g/L) increased up to 20 times than control (1.21 g/L), with a significant increase in daidzein (17.05 g/L) and genistein (9.68 g/L). Addition of 8U of ß-glucosidase into soymilk significantly increased the conversion of isoflavone in ENTII (daidzein: 0.46 g/L; genistein: 0.18 g/L) than in ENTI (daidzein: 0.33 g/L; genistein: 0.20 g/L). The particle size analysis and confocal micrographs of digesta also suggest the size of fat and protein in gastric phase to be smaller than in intestinal phase. The results indicate the prospective to develop soy-based fermented products capable of releasing high isoflavone in the digestive system.

Analysis of the F2LR3 (PAR4) Single Nucleotide Polymorphism (rs773902) in an Indigenous Australian Population.

The F2RL3 gene encoding protease activated receptor 4 (PAR4) contains a single nucleotide variant, rs773902, that is functional. The resulting PAR4 variants, Thr120, and Ala120, are known to differently affect platelet reactivity to thrombin. Significant population differences in the frequency of the allele indicate it may be an important determinant in the ethnic differences that exist in thrombosis and hemostasis, and for patient outcomes to PAR antagonist anti-platelet therapies. Here we determined the frequency of rs773902 in an Indigenous Australian group comprising 467 individuals from the Tiwi Islands. These people experience high rates of renal disease that may be related to platelet and PAR4 function and are potential recipients of PAR-antagonist treatments. The rs773902 minor allele frequency (Thr120) in the Tiwi Islanders was 0.32, which is similar to European and Asian groups and substantially lower than Melanesians and some African groups. Logistic regression and allele distortion testing revealed no significant associations between the variant and several markers of renal function, as well as blood glucose and blood pressure. These findings suggest that rs773902 is not an important determinant for renal disease in this Indigenous Australian group. However, the relationships between rs773902 genotype and platelet and drug responsiveness in the Tiwi, and the allele frequency in other Indigenous Australian groups should be evaluated.

Sequential aspects of cream cheese texture perception using temporal dominance of sensations (TDS) tool and its relation with flow and lubrication behaviour.

Temporal Dominance of Sensations (TDS) is a sensory descriptive tool that provides information about the sequence of the dominant attributes in a product when processed in the oral cavity and their subsequent changes over time. In humans, texture perception of any food is a dynamic process that plays a major role in the acceptance of the food. The TDS tool allows understanding the dynamic textural sensation in the mouth. In this work, this tool was applied to study the creaminess, smoothness, cohesiveness, thickness, and mouthfeel of cream cheese added with ß-glucan and phytosterol (esterified and native). A trained sensory panel perceived the dynamic textural sensations introduced by cream cheese with and without these functional ingredients. The TDS data obtained showed that the first dominant attribute depends on the ingredient that make-up the cream cheese. The textural attributes of cohesiveness, thickness, and smoothness were the first dominant attributes while mouth coating significantly dominated at the end of mastication for all cream cheese added with functional ingredients. However, in reduced-fat cream cheese without functional ingredients mouth coating was the only significant dominant attribute (dominance rate of 40%) throughout the oral processing. The TDS results complemented the instrumental characterisation of the cream cheese sample where the addition of these ingredients significantly increase the firmness (from 0.85 up to 1.99 N) and made them less spreadable (from 6.6 up to 14.8 N/s). The rheology/tribology data also show a relationship with the thickness/creaminess sensations. The use of phytosterol in native form tended to increase the viscosity of the cream cheese, while the esterified form contributed to the lubrication properties similar to fat, lowering the coefficient of friction. The TDS profile of high-fat cream cheese, characterised by the highest dominance rate (70%) of creaminess also represented the least coefficient of friction.

Texture and lubrication properties of functional cream cheese: Effect of ß-glucan and phytosterol.

The effect of ß-glucan (BG) and phytosterols (PS) as fat replacers on textural, microstructural, and lubrication properties of reduced-fat cream cheese was investigated. Five formulations (BG-PS ester, PS ester, BG-PS emulsions, PS emulsions, and BG) of cream cheese with added ß-glucan and phytosterols (in emulsified and esterified form) were investigated and compared with commercial cheese. Among the five formulations used in this experiment, the effect of ß-glucan appeared to be more pronounced imparting increased viscosity and firmness to reduced-fat cream cheese, similar to commercial high-fat cream cheese sample. Conversely, in lubrication study both the phytosterols (esterified and emulsified) were effective in reducing the coefficient of friction resulting in a more spreadable cream cheese. The microstructure of cream cheese with added ß-glucan and phytosterols, used solo or in combination, exhibited more open structure of casein matrix, although differences in fat globule size were observed. Cream cheese made from PS emulsion (emulsified from phytosterols powder) resulted in a larger fat globule size than PS ester and ß-glucan as shown by confocal laser scanning microscopy. In addition, the particle size distribution of cream cheese formulation containing ß-glucan only showed a monomodal curves with small globule size, while a bimodal distribution with larger particle size was observed from cream cheese with phytosterols alone. PRACTICAL APPLICATIONS: Reducing the fat content, impacts the quality characteristics of low-fat cream cheese. This research showed a novel way to incorporate ß-glucan and phytosterols as fat replacers and functional ingredients in cream cheese formulation that improves its textural and lubrication properties. In addition, this article discusses the effect of ß-glucan and phytosterols used both individually and in combination on the particle size, microstructural and rheological characteristics of functional cream cheese and compares them against commercial product. The potential use of ß-glucan and phytosterols as fat replacers in low-fat cream cheese will be useful for the industries to develop functional cream cheese that meets consumers demand.