Albumin is the major carrier protein for PFOS, PFOA, PFHxS, PFNA and PFDA in human plasma.

Perfluoroalkyl (PFAS) substances are widespread in the environment and in organisms. The fact that exposure to PFAS is associated with elevated cholesterol levels is a major concern for human health. Previous investigations, in which bovine serum albumin was frequently studied, indicate that PFOS, PFOA and PFNA bind to serum albumin. However, it is critical to know whether these and other PFAS have a preference for the protein or the lipid fraction in native human blood fractions. For this reason, blood samples from four young healthy volunteers (two women, two men, 23-31 years old) were used for protein size separation and fractionation by the Cohn method in combination with serial ultracentrifugation. The plasma fractions were analyzed for 11 PFAS using high-performance tandem mass spectrometry (HPLC-MS/MS). Although the data are based on a small sample, they clearly show that albumin is the most important carrier protein for PFOS, PFOA, PFHxS, PFNA and PFDA in native human plasma. These five compounds have very little or no affinity for lipoproteins. The confirmation of their transport through albumin is important for the epidemiology of PFAS. The present results must be verified by the examination of a larger number of persons.

Egg quality and egg albumen property of domestic chicken, duck, goose, turkey, quail, and pigeon.

Poultry eggs from different species varied significantly, due to their divergent process of evolution. However, the information on egg characteristics has been limited mostly to chicken. The current study compared the egg quality, albumen physical and nutritional property for domesticated chicken, duck, goose, turkey, quail, and pigeon. Egg quality traits among different species differed significantly, such as egg weight (from 11 to 139 g), egg shape (from 1.28 to 1.44), proportion of yolk (from 19.3 to 37.9%), and breaking strength (from 0.91 to 8.04 kg/cm2). For the physical property of albumen gel, pigeon egg was the most special one. The albumen gel of pigeon egg had a transparent appearance (A = 1.23), and it had the highest hardness (121.7 g) and water-holding capacity (96%) but a medium level of total cutting work (440 g⋅s). Hence, it was easy for deformation but was hard to cut off when external force was applied. For nutritional compositions of egg albumen, goose egg had the highest moisture (89.21%) and lowest crude protein (8.5%) contents. Specific to amino acid, glutamic acid was found the most abundant in albumen of all six species. Egg albumen of turkey had the highest quantity of essential amino acids (EAA) and total amino acids (TAA), while duck and goose had relatively higher EAA/TAA ratios. Both PCA and cluster analysis revealed the high similarity of amino acid composition between duck and goose, and among quail, turkey, and chicken. The comparative data will improve the understanding of egg qualities of major poultry species and can be helpful in technological application of egg albumen.

Unbound monomers do diffuse through the dentin barrier.

OBJECTIVES: Assessing the role of dentinal fluid proteins in trans-dentinal diffusion of free monomers in vitro. METHODS: An artificial pulp chamber (APC) topped human dentin disks was used. A simplified two-step etch-and-rinse adhesive was formulated with 2-hydroethyl-methacrylate (HEMA), Bisphenol-A-diglycidyl-methacrylate (BisGMA), using Camphorquinone/tertiary amine as initiators. Two extraction media were used: buffered saline (Control), buffered saline with 1% bovine serum albumin (BSA). Samples were acid-etched, rinsed, air dried. Simplified primer was used, adhesive applied then light cured with a LED curing. Monomer diffusion was assessed by reverse phase HPLC. RESULTS: Quantifiable amounts of HEMA were detected in both extraction media while BisGMA was present in quantifiable amounts in BSA medium only. Diffused monomers concentrations were significantly higher for both monomers in BSA extraction medium. SIGNIFICANCE: Albumin is sometimes referred to as taxi protein for its ability to bind and transport hydrophobic ligands. From our results, we hypothesized that albumin can also transport unbound monomers released from dental adhesive through the dentin barrier. However, dentinal fluid proteins like albumin could have significant effect on monomer diffusion through dentin to the dental pulp transporting highly hydrophobic molecules like BisGMA and enhancing diffusion of more hydrophilic ones like HEMA. These results demonstrate a new possible mechanism for cytotoxicity of resin monomers.

Fibroblasts Rendered Antifibrotic, Antiapoptotic, and Angiogenic by Priming With Cardiosphere-Derived Extracellular Membrane Vesicles.

BACKGROUND: Cardiosphere-derived cells mediate therapeutic regeneration in patients after myocardial infarction and are undergoing further clinical testing for cardiomyopathy. The beneficial effects of cardiosphere-derived cells are mediated by the secretion of exosomes and possibly other extracellular membrane vesicles (EMVs). OBJECTIVES: This study sought to investigate the effect of cardiosphere-derived EMVs (CSp-EMVs) on fibroblasts in vitro and tested whether priming with CSp-EMVs could confer salutary properties on fibroblasts in vivo. METHODS: CSp-EMVs were isolated from serum-free media conditioned for 3 days by cardiospheres. Dermal fibroblasts were primed with CSp-EMVs for 24 h followed by exosomal micro-ribonucleic acid profiling. In vivo, we injected CSp-EMV-primed or -unprimed dermal fibroblasts (or CSp-EMVs) in a chronic rat model of myocardial infarction and defined the functional and structural consequences. RESULTS: CSp-EMVs amplified their own biological signals: exposure of "inert" fibroblasts to CSp-EMVs rendered the fibroblasts therapeutic. Intramyocardially injected CSp-EMV-primed (but not unprimed) fibroblasts increased global pump function and vessel density while reducing scar mass. CSp-EMV priming caused fibroblasts to secrete much higher levels of stromal-cell-derived factor 1 and vascular endothelial growth factor and dramatically changed the micro-ribonucleic acid profile of fibroblast-secreted EMVs in vitro. The priming was followed by significant angiogenic and cardioprotective effects. CONCLUSIONS: CSp-EMVs alter fibroblast phenotype and secretome in a salutary positive-feedback loop. The phenotypic conversion of inert cells to therapeutically active cells reveals a novel mechanism for amplification of exosome bioactivity.

Morphological and immunohistochemical analyses of soluble proteins in mucous membranes of living mouse intestines by cryotechniques.

We have performed immunohistochemical or ultrastructural analyses of living mouse small intestines using Epon blocks prepared by 'in vivo cryotechnique' (IVCT). By electron microscopy, intracellular ultrastructures of epithelial cells were well preserved in tissue areas 5-10 µm away from cryogen-contact surface tissues. Their microvilli contained dynamically waving actin filaments, and highly electron-dense organelles, such as mitochondria, were seen under the widely organized terminal web. By quick-freezing of fresh resected tissues (FT-QF), many erythrocytes were congested within blood vessels due to loss of blood pressure. By immersion-fixation (IM-DH) and perfusion-fixation (PF-DH), small vacuoles were often seen in the cytoplasm of epithelial cells, and their intercellular spaces were also dilated. Moreover, actin filament bundles were irregular in cross sections of microvilli, compared with those with IVCT. Epon-embedded thick sections were treated with sodium ethoxide, followed by antigen retrieval and immunostained for immunoglobulin A (IgA), Ig kappa light chain (Igκ), J-chain and albumin. By cryotechniques, IgA immunoreactivity was detected as tiny dot-like patterns in cytoplasm of some epithelial cells. Both J-chain and Igκ immunoreactivities were detected in the same local areas as those of IgA. By FT-QF, however, the IgA immunoreactivity was more weakly detected, compared with that with IVCT. In thick sections prepared by IM-DH and PF-DH, it was rarely observed in both plasma and epithelial cells. Another albumin was diffusely immunolocalized in extracellular matrices of mucous membranes and also within blood vessels. Thus, IVCT was useful for preservation of soluble proteins and ultrastructural analyses of dynamically changing epithelial cells of living mouse small intestines.

Realización entre la hipoalbuminemia y la supervivencia libre de amputación mayor en pacientes revascularizados por isquemia crítica de la extremidad inferior / Relation ship between hypoalbuminemia and amputation free survival in patients undergoing revascularization due tolower limb critical ischemia

Introducción: La hipoalbuminemia es un marcador de mal pronóstico en múltiples situaciones clínicas; sin embargo, aún no se ha establecido fehacientemente su implicación en los resultados tras cirugía arterial de la extremidad inferior. Este trabajo evalúa el impacto de la hipoalbuminemia en pacientes sometidos a revascularización por isquemia crítica de la extremidad inferior. Material y métodos: Se diseñó un estudio restrospectivo observacional de pacientes revascularizados por isquemia crítica en el Hospital Clínico Universitario de Valladolid. Se clasificó a los pacientes en dos grupos según la presencia de hipo o normo albuminemia en la analítica de sangre periférica preoperatoria. Se compararon ambos grupos para estimar diferencias en cuanto a amputación mayor, exitus, supervivencia libre de amputación mayor, estancia postoperatoria y complicaciones. Resultados: De los 529 pacientes incluidos en el trabajo, 61 (11,5%) presentaron hipoalbuminemia; este grupo presentó a 30 días mayor tasa de amputación mayor (33,3% versus 19,5%), y al año mayor mortalidad (34% versus 13,8%) y mayor tasa de amputación (28,6% versus 17,3%). La supervivencia libre de amputación mayor fue peor en pacientes con hipoalbuminemia (45%, 37%, 33%, 33% y 22% versus 70%, 64%, 58%, 51% y 48% a 1, 2, 3, 4 y 5 años), así como la tasas de complicaciones postoperatorias respiratorias (23% versus 6,4%). Conclusión: La hipoalbuminemia preoperatoria en pacientes revascularizados por isquemia crítica de la extremidad inferior se asocia a peores resultados clínicos en términos de muerte y amputación mayor a corto y medio plazo, así como a mayor tasa de complicaciones respiratorias postoperatorias

Introduction: Hypoalbuminemia is a marker of poor prognosis in multiple clinical settings; however, has not yet been convincingly established its involvement in the results after arterial surgery of the lower limb. This paper evaluates the impact of hypoalbuminemia in patients undergoing revascularization for critical ischemia of the lower limb. Material and Methods: A retrospective observational study of patients who underwent revascularization for critical limb ischemia in the University Hospital of Valladolid was designed. We classified the patients into two groups according to the presence of calcinosis or not when assessing the ankle-brachial index. Both groups were compared to estimate differences in major amputation, exitus, major amputation free survival, hospital stay and complications. Results: Of the 529 patients included in the study, 61 (11,5%) had arterial hypoalbuminemia; these group had a 30 days higher major amputation rate (33,3% versus 19,5%), and a year higher mortality (34% versus 13,8%) and major amputation rate (28,6% versus 17,3%). One year amputation free survival was worse in patients with hypoalbuminemia(45%, 37%, 33%, 33% y 22% versus 70%, 64%, 58%, 51% y 48% at 1, 2, 3, 4 y 5 years), as well as the rate of respiratory postoperative complications (23% versus 6.4%). Conclusion: Preoperative hypoalbuminemia in patients revascularized by critical lower limb ischemia is associated with worse short and medium term clinical outcomes in terms of exitus and major amputation, as well as a higher rate of post operatory respiratory complications

Albumin administration in the acutely ill: what is new and where next?

Albumin solutions have been used worldwide for the treatment of critically ill patients since they became commercially available in the 1940s. However, their use has become the subject of criticism and debate in more recent years. Importantly, all fluid solutions have potential benefits and drawbacks. Large multicenter randomized studies have provided valuable data regarding the safety of albumin solutions, and have begun to clarify which groups of patients are most likely to benefit from their use. However, many questions remain related to where exactly albumin fits within our fluid choices. Here, we briefly summarize some of the physiology and history of albumin use in intensive care before offering some evidence-based guidance for albumin use in critically ill patients.

Albumin: physiologic and clinical effects on lung function.

Fluid resuscitation is one of the most frequent and necessary practices in clinical medicine and is an integral part of the initial stabilization of critically ill, hypovolemic patients. Longstanding debate and conflicting evidence surround the use of both colloid and crystalloid fluid resuscitation in these patients. The basis of this debate is heavily rooted in the physiological understanding of Starling's forces. In this review, we aim to highlight the ongoing debate of albumin versus crystalloid resuscitation both broadly and as it relates to lung function, and will discuss the current state-of-the-art, starting from an historic perspective and progressing through a review of both physiologic and clinical evidence. Despite the biologic and physiologic plausibility of therapeutic benefit, the current evidence base does not support the routine use of albumin administration to improve patient survival or prevent respiratory dysfunction.

Human albumin: old, new, and emerging applications.

Human serum albumin has been widely used in an array of clinical settings for nearly 7 decades. Although there is no evidence to support the use of albumin rather than crystalloid in acute volume resuscitation, many clinicians continue to use albumin because it has other important physiologic effects besides the oncotic function. In keeping with the improved understanding of albumin physiology and pathophysiology of many acute and chronic diseases, use of albumin for medical applications has increased in recent years. This, along with increased costs of manufacturing and lower production volume of medical-grade albumin, has lead to an ongoing shortage and rapid increase in albumin prices. This review is based on the analysis of major publications, related to albumin chemistry, physiology, and medical uses including guidelines developed by professional and governmental organizations. Results reflect current knowledge about the role of albumin in health and disease and relevance of albumin therapy in specific clinical settings. Albumin therapy is currently recommended in spontaneous bacterial peritonitis with ascites, refractory ascites not responsive to diuretics, large-volume paracentesis, post-paracentesis syndrome, and the treatment of hepatorenal syndrome as an adjunct to vasoconstrictors. New indications for albumin therapy are linked to the antioxidant activity of albumin and its effects on capillary integrity. In recent years, large-pore hemofiltration and albumin exchange have emerged as promising liver support therapies for liver failure and other toxic syndromes. They are designed to remove a broad range of blood-borne toxins and to restore normal functions of the circulating albumin by replacing defective forms of albumin and albumin molecules saturated with toxins with normal albumin. In view of the ongoing worldwide shortage and high cost of human albumin (native and recombinant), new usage criteria, protocols, and guidelines for appropriate utilization of albumin are needed.

Albumin: pathophysiologic basis of its role in the treatment of cirrhosis and its complications.

Since the introduction of human serum albumin as a plasma expander in the 1940s, considerable research has allowed a better understanding of its biochemical properties and potential clinical benefits. Albumin has a complex structure, which is responsible for a variety of biological functions. In disease, the albumin molecule is susceptible to modifications that may alter its biological activity. During the last decades, different methods to measure albumin function have been developed. Recent studies have shown that not only albumin concentration but also albumin function is reduced in liver failure. This observation led to the concept of effective albumin concentration, which represents the fact that plasma albumin concentration does not reflect its function. Indeed, in liver disease albumin function is several times less than its concentration. In patients with cirrhosis, albumin infusion reduces mortality in patients with spontaneous bacterial peritonitis and improves outcome following large volume paracentesis. In combination with vasoconstrictors, albumin is useful in the management of patients with hepatorenal syndrome. Its role is being investigated in a large number of indications, which rely on its volume and nonvolume expansion functions such as stroke, severe sepsis, Alzheimer's disease, malaria, burns, and ovarian hyperstimulation syndrome. This review explores the above concepts, reviews the available evidence for the use of albumin in liver diseases, defines therapeutic limitations, and explores the challenges that should be addressed in future research.

Albumin upregulates eNOS mRNA through ETRA/B in human proximal tubular epithelial cells.

BACKGROUND: Proximal tubular cells respond to proteinuria by expressing several cytokines and inflammatory molecules that induce interstitial fibrosis. Increased attention has been drawn toward the systems of endothelin (ET) and nitric oxide (NO). This work contributes to the elucidation of the interplay between these two systems in proximal tubular epithelial cells (PTECs) after exposure in proteinuric conditions. METHODS: HK-2 cells, a human PTEC line, were incubated with albumin, simulating proteinuric conditions. Cells were then lysed and either total RNA was isolated or whole cell extracts were prepared. PreproET-1, ET receptors (ETRA and ETRB) and NO synthases (eNOS, iNOS) mRNA accumulation was estimated by RT-PCR, and proteins by Western blot analysis. NO production was assessed using Griess reaction. Furthermore, we treated HK-2 cells with NO donor sodium nitroprusside, NO inhibitor L-NAME, ETRA inhibitor BQ123, ETRB inhibitor BQ788 and purified ET-1, and investigated the potential interplay between albumin-induced stimulation of NO or ET-1 systems. RESULTS: We found that albumin upregulates preproET-1, ETRA, ETRB, eNOS and iNOS mRNA as well as protein and stimulates NO production. Additionally, we recorded an ETRA/B dependent regulation of albumin-induced eNOS expression. CONCLUSIONS: For the first time an in vitro albumin-induced ET-1 and NO interplay was revealed.

Homocysteinylated albumin promotes increased monocyte-endothelial cell adhesion and up-regulation of MCP1, Hsp60 and ADAM17.

RATIONALE: The cardiovascular risk factor homocysteine is mainly bound to proteins in human plasma, and it has been hypothesized that homocysteinylated proteins are important mediators of the toxic effects of hyperhomocysteinemia. It has been recently demonstrated that homocysteinylated proteins are elevated in hemodialysis patients, a high cardiovascular risk population, and that homocysteinylated albumin shows altered properties. OBJECTIVE: Aim of this work was to investigate the effects of homocysteinylated albumin - the circulating form of this amino acid, utilized at the concentration present in uremia - on monocyte adhesion to a human endothelial cell culture monolayer and the relevant molecular changes induced at both cell levels. METHODS AND RESULTS: Treated endothelial cells showed a significant increase in monocyte adhesion. Endothelial cells showed after treatment a significant, specific and time-dependent increase in ICAM1 and VCAM1. Expression profiling and real time PCR, as well as protein analysis, showed an increase in the expression of genes encoding for chemokines/cytokines regulating the adhesion process and mediators of vascular remodeling (ADAM17, MCP1, and Hsp60). The mature form of ADAM17 was also increased as well as Tnf-α released in the cell medium. At monocyte level, treatment induced up-regulation of ICAM1, MCP1 and its receptor CCR2. CONCLUSIONS: Treatment with homocysteinylated albumin specifically increases monocyte adhesion to endothelial cells through up-regulation of effectors involved in vascular remodeling.

PKB/Akt partners with Dab2 in albumin endocytosis.

Albumin in the glomerular filtrate is normally retrieved by concerted efforts of clathrin, LDL-type receptor megalin- and clathrin-associated sorting proteins. In glomerular diseases, albumin overload triggers a proapoptotic and inflammatory response contributing to tubulointerstitial fibrosis and tubular atrophy. The relationship between albumin overload-induced proximal tubule injury and albumin endocytosis remains to be discovered. We investigated presence of a possible overlap between endocytosis and cell survival. We showed a novel interaction between prosurvival protein, protein kinase B (PKB/Akt), and adaptor protein, disabled 2 (Dab2), with coimmunoprecipitation. Further delineation of this interaction by GST pull-down experiments utilizing different Dab2 constructs identified proline-rich domain as the interacting partner. Expression of Dab2 and PKB/Akt was downregulated at high concentrations of albumin associated with apoptosis. We then examined the physiological relevance of this interaction with functional studies. Overexpression of PKB/Akt increased albumin uptake in human proximal tubule cells. Conversely, inhibition of PKB/Akt with a nonselective Akt/PKB signaling inhibitor-2 and a dominant negative construct of PKB/Akt resulted in a decrease in albumin uptake. Inhibition of Dab2 by silencing RNA abolished PKB/Akt-induced albumin uptake demonstrating the physiological importance of this novel interaction. We concluded that PKB/Akt is part of an endocytic machinery and it mediates albumin uptake through its interaction with Dab2. The role that PKB/Akt plays in the endocytic cascade may dictate its decreased expression in proteinuric states in an attempt to limit albumin endocytosis that may tilt the balance between cell survival and apoptosis toward cell death.

Application of albumin-grafted scaffolds to promote neocartilage formation.

This study investigates the capacity of albumin-grafted biomaterials as tissue engineering scaffolds to regenerate cartilaginous components. Porcine knee chondrocytes were seeded and cultivated in porous ternary matrix consisting of polyethylene oxide, chitin, and chitosan with surface albumin. The results revealed that the quantity of albumin did not affect the viability of porcine knee chondrocytes in the constructs. However, a high grafting concentration of albumin favored the adhesion of porcine knee chondrocytes on the scaffolding pore surface. After cultivation over 4 weeks, an increase in the concentration of albumin enhanced the quantities of porcine knee chondrocytes, glycosaminoglycans, and collagen in the constructs. The histological staining of porcine knee chondrocytes showed an active chondrocytic growth in the albumin-grafted constructs. In addition, the safranin-O staining indicated that the surface albumin could stabilize the secretion of glycosaminoglycans. Moreover, the immunochemical staining against type II collagen exhibited a regular production of collagen by phenotypic porcine knee chondrocytes in the constructs. Albumin-grafted polyethylene oxide/chitin/chitosan scaffolds can be a promising biomimetic substrate in neocartilage formation.

Impaired left ventricular systolic function and increased brachial-ankle pulse-wave velocity are independently associated with rapid renal function progression.

Heart failure and increased arterial stiffness are associated with declining renal function. Few studies have evaluated the association between left ventricular ejection fraction (LVEF) and brachial-ankle pulse-wave velocity (baPWV) and renal function progression. The aim of this study was to assess whether LVEF<40% and baPWV are associated with a decline in the estimated glomerular filtration rate (eGFR) and the progression to a renal end point of ≥25% decline in eGFR. This longitudinal study included 167 patients. The baPWV was measured with an ankle-brachial index-form device. The change in renal function was estimated by eGFR slope. The renal end point was defined as ≥25% decline in eGFR. Clinical and echocardiographic parameters were compared and analyzed. After a multivariate analysis, serum hematocrit was positively associated with eGFR slope, and diabetes mellitus, baPWV (P=0.031) and LVEF<40% (P=0.001) were negatively associated with eGFR slope. Forty patients reached the renal end point. Multivariate, forward Cox regression analysis found that lower serum albumin and hematocrit levels, higher triglyceride levels, higher baPWV (P=0.039) and LVEF<40% (P<0.001) were independently associated with progression to the renal end point. Our results show that LVEF<40% and increased baPWV are independently associated with renal function decline and progression to the renal end point.

[Resident cardiac stem cells].

The search for sources of stem/progenitor cells the use of which has a potential to affect course of ischemic heart disease and chronic heart failure is conducted nowadays in many countries. Resident cardiac stem cells (CSC) were revealed during recent years on the basis of expression of c-kit, sca-1, MDR1, and islet-1 markers. In vitro experiments demonstrated possibility of their differentiation into cardiomyocytes, smooth muscle cell and endothelial cells. Introduction of CSC in injured myocardium in animals facilitated its partial repair and short term improvement of cardiac function. This holds promise for the use of these cells in the future. In the review we have attempted to summarize literature data on resident CSC and their application for the treatment of heart diseases.

Leukocyte rolling and adhesion both contribute to regulation of microvascular permeability to albumin via ligation of ICAM-1.

Activated neutrophils interacting with the vessel wall can alter vascular permeability to macromolecules such as albumin via release of various secretion products that induce changes in the endothelial monolayer. In the current work we used cremaster microvessels of anesthetized mice to show that, in addition to this paracrine mechanism, leukocyte ligation of endothelial ICAM-1 directly activates endothelial cell (EC) signaling, altering EC permeability to albumin [i.e., solute permeability (P(s))]. We show that antibody cross-linking of surface ICAM-1 in intact microvessels is sufficient to increase P(s) even in the absence of interacting leukocytes. Unstimulated arterioles do not support leukocyte-EC interactions, but despite this, antibody ligation of ICAM-1 in these vessels induced a twofold increase in P(s). Similarly, in venules that were depleted of interacting neutrophils, P(s) was decreased to below resting levels and was restored by ligation of ICAM-1. Use of function-blocking antibodies to separately block leukocyte rolling or adhesion under unstimulated or TNF-α-activated conditions established that both rolling and adhered leukocytes contribute to P(s) regulation in situ. Both rolling and adhesion activated EC-dependent signaling mechanisms that increased P(s). ICAM-1 ligation with primary antibody alone or primary followed by secondary antibodies showed that regulation of P(s) is directly dependent on the degree of ICAM-1 clustering. Under physiological versus inflamed conditions, respectively, this ICAM-1 clustering-dependent regulation of P(s) switches from PKC dependent and Src independent to Src dependent and PKC independent. This study thus identifies a new mechanism by which antiadhesion treatment may constitute a potential therapy for tissue edema.