Albumin turnover: experimental approach and its application in health and renal diseases

Impact of Albumin Leakage on the Mortality of Patients Receiving Hemodialysis or Online Hemodiafiltration

Background: Online hemodiafiltration (OHDF) has a lower mortality rate than hemodialysis (HD). We aimed to investigate the impact of the albumin leakage on the mortality of patients receiving HD or OHDF. Methods: In this single-center study, consecutive patients receiving renal replacement therapy between January and April 2018 were retrospectively registered. Using (1:1) propensity score matching, 3-year all-cause mortality was compared between patients receiving HD and OHDF, and the impact of albumin leakage on the mortality rate in both groups was investigated. Results: Of the 460 patients, 137 patients receiving HD were matched with an equal number of patients receiving OHDF. OHDF was associated with higher albumin leakage (p < 0.001) and a lower mortality than HD (log-rank test, p < 0.001). Albumin leakage was associated with mortality in patients receiving HD (per 1 g increase, hazard ratio (HR): 0.495, 95% confidence interval (CI): 0.275-0.888) and patients receiving OHDF (per 1 g increase, HR: 0.734, 95% CI: 0.588-0.915). Patients receiving HD, with the highest albumin leakage tertile (>3 g), had a similar mortality rate to patients receiving OHDF, with similar albumin leakage. Conclusions: The negative relationship between albumin leakage and mortality suggests the benefit of removing middle- to -large-molecular-weight substances to improve survival.

Efficacy of a single-dose albendazole against lancet liver fluke Dicrocoelium dendriticum and liver enzymes activity in naturally infected sheep

Infections with D. dendriticum are distributed worldwide and mostly associated with ruminant livestock. Depending on the length and strength of the infection it can be manifested with losses in milk production, reductions in milk and wool quality, decreased weight gains, reproductive performance and poor carcass quality. The objective of this study was to determine the efficacy of albendazole (ABZ) against the lancet liver fluke Dicrocoelium dendriticum in naturally infected sheep using parasitological methods. Twenty-four sheep were divided into four groups: two untreated control groups (C1, C2) and two treated groups (T1, T2), with six animals in each group. The sheep in the treated groups were administered a single oral dose (15 mg/kg bwt) of ABZ suspension. After ABZ treatment the animals were slaughtered on Day 14 (groups C1, T1) and Day 30 (groups C2, T2) and were necropsied. Coprological therapeutic ABZ efficacy reached 92.4% on Day 14 (P < 0.001) and 88.5% on Day 30 (P < 0.001). On Day 30, the serum activities of hepatic and cholestatic enzymes including serological analysis of total protein concentration (TP) and protein fractions were evaluated. Significant decrease of aspartate aminotransferase (AST) (P < 0.01) and gamma-glutamyltransferase (GGT) (P < 0.05) activity by 36.9% and 34.6%, respectively, were detected for sheep in T2 group. These enzymes showed a strong positive correlation to fluke burden: AST (r = 0.654) and GGT (r = 0.768), respectively (P < 0.05). Additionally, the electrophoretic analysis of serum total protein and protein fraction concentrations revealed minimal hypoproteinemia and hyperalbuminemia after ABZ treatment. The decrease of liver enzyme activities and their correlation with fluke burden may indicate recovery of hepatocellular and biliary damage following the reduction of fluke burdens after ABZ therapy. A decline in AST and GGT activity could serve as a valuable adjunct bioindicator of liver damage and fluke reduction after treatment of dicrocoeliosis in naturally infected sheep.

Salivary Adiponectin and Albumin Levels on the Gingival Conditions of Patients Undergoing Bariatric Surgery: A Cohort Study

This study analyzed the salivary proteomics, adiponectin and albumin, related to weight loss and periodontitis in patients undergoing bariatric surgery. This study included fourteen patients with morbid obesity (body mass index, BMI > 40 kg/m²) who underwent bariatric surgery Roux-en-Y gastric bypass (RYGB) in System Health Public in Brazil. Data on demographic and anthropometric measures were extracted from medical records preoperatively and 6 and 12 months post-surgery. The variables assessed were: probing pocket depth (PPD), clinical attachment loss (CAL), bleeding on probing (BOP), and stimulated whole-mouth saliva. In this study, saliva samples were analyzed by electrophoresis and immunoblotting. The ELISA kit was used to measure the MMP8 levels to determine potential markers for obesity. Adiponectin and albumin levels were also evaluated. Weight loss was associated with significant changes in patients' periodontal clinical data. Although 7 out of 10 periodontal patients showed an increase in salivary adiponectin levels after root planning treatment, when analyzed by Western blotting, the increase was not statistically significant (21.1 ± 4.8 to 26.3 ± 9.4 arbitrary units, p > 0.99). There was no correlation between albumin levels and salivary adiponectin pre-surgery, nor 6 months or 12 months after surgery. Weight loss was not improved by low-grade inflammation in bariatric patients, since albumin levels were similar between periods. Periodontitis is an inflammatory disease that is modulated by several factors, among which adiponectin plays an important role for the treatment of periodontal disease.

Facile Fabrication of Transparent and Opaque Albumin Methacryloyl Gels with Highly Improved Mechanical Properties and Controlled Pore Structures

For porous protein scaffolds to be employed in tissue-engineered structures, the development of cost-effective, macroporous, and mechanically improved protein-based hydrogels, without compromising the original properties of native protein, is crucial. Here, we introduced a facile method of albumin methacryloyl transparent hydrogels and opaque cryogels with adjustable porosity and improved mechanical characteristics via controlling polymerization temperatures (room temperature and −80 °C). The structural, morphological, mechanical, and physical characteristics of both porous albumin methacryloyl biomaterials were investigated using FTIR, CD, SEM, XRD, compression tests, TGA, and swelling behavior. The biodegradation and biocompatibility of the various gels were also carefully examined. Albumin methacryloyl opaque cryogels outperformed their counterpart transparent hydrogels in terms of mechanical characteristics and interconnecting macropores. Both materials demonstrated high mineralization potential as well as good cell compatibility. The solvation and phase separation owing to ice crystal formation during polymerization are attributed to the transparency of hydrogels and opacity of cryogels, respectively, suggesting that two fully protein-based hydrogels could be used as visible detectors/sensors in medical devices or bone regeneration scaffolds in the future.

Zinc-Substituted Pheophorbide A Is a Safe and Efficient Antivascular Photodynamic Agent

The present study focuses on the photodynamic activity of zinc-substituted pheophorbide a against human endothelial cells. Previously, zinc pheophorbide a has been shown to be a very potent photosensitizer but also a strong albumin binder. Binding to albumin significantly reduces its availability to cancer cells, which may necessitate the use of relatively high doses. Here we show that zinc pheophorbide a is very effective against vascular endothelial cells, even in its albumin-complexed form. Albumin complexation increases the lysosomal accumulation of the drug, thus enhancing its efficiency. Zinc pheophorbide a at nanomolar concentrations induces endothelial cell death via apoptosis, which in many cases is considered a desirable cell death mode because of its anti-inflammatory effect. Additionally, we demonstrate that in comparison to tumor cells, endothelial cells are much more susceptible to photodynamic treatment with the use of the investigated compound. Our findings demonstrate that zinc pheophorbide a is a very promising photosensitizer for use in vascular-targeted photodynamic therapy against solid tumors, acting as a vascular shutdown inducer. It can also possibly find application in the treatment of a range of vascular disorders. Numerous properties of zinc pheophorbide a are comparable or even more favorable than those of the well-known photosensitizer of a similar structure, palladium bacteriopheophorbide (TOOKAD^®).

Colostrogenesis: Role and Mechanism of the Bovine Fc Receptor of the Neonate (FcRn)

Colostrogenesis is a separate and unique phase of mammary epithelial cell activity occurring in the weeks before parturition and rather abruptly ending after birth in the bovine. It has been the focus of research to define what controls this process and how it produces high concentrations of specific biologically active components important for the neonate. In this review we consider colostrum composition and focus upon components that appear in first milked colostrum in concentrations exceeding that in blood serum. The Fc Receptor of the Neonate (FcRn) is recognized as the major immunoglobulin G (IgG) and albumin binding protein that accounts for the proteins' long half-lives. We integrate the action of the pinocytotic (fluid phase) uptake of extracellular components and merge them with FcRn in sorting endosomes. We define and explore the means of binding, sorting, and the transcytotic delivery of IgG1 while recycling IgG2 and albumin. We consider the means of releasing the ligands from the receptor within the endosome and describe a new secretion mechanism of cargo release into colostrum without the appearance of FcRn itself in colostrum. We integrate the insulin-like growth factor family, some of which are highly concentrated bioactive components of colostrum, with the mechanisms related to FcRn endosome action. In addition to secretion, we highlight the recent findings of a role of the FcRn in phagocytosis and antigen presentation and relate its significant and abrupt change in cellular location after parturition to a role in the prevention and resistance to mastitis infections.

Biodegradable Small-Scale Swimmers for Biomedical Applications

Most forms of biomatter are ephemeral, which means they transform or deteriorate after a certain time. From this perspective, implantable healthcare devices designed for temporary treatments should exhibit the ability to degrade and either blend in with healthy tissues, or be cleared from the body with minimal disruption after accomplishing their designated tasks. This topic is currently being investigated in the field of biomedical micro- and nanoswimmers. These tiny devices have the ability to move through fluids by converting physical or chemical energy into motion. Several architectures of these devices have been designed to mimic the motion strategies of nature's motile microorganisms and cells. Due to their motion abilities, these devices have been proposed as minimally invasive tools for precision healthcare applications. Hence, a natural progression in this field is to produce motile structures that can adopt, or even surpass, similar transient features as biological systems. The fate of small-scale swimmers after accomplishing their therapeutic mission is critical for the successful translation of small-scale swimmers' technologies into clinical applications. In this review, recent research efforts are summarized on the topic of biodegradable micro- and nanoswimmers for biomedical applications, with a focus on targeted therapeutic delivery.

One ring is not enough to rule them all. Albumin-dependent ABCG2-mediated transport of chlorophyll-derived photosensitizers

Breast cancer resistance protein (BCRP, ABCG2) is a member of the ATP-binding-cassette (ABC) superfamily of membrane transporters. It is involved in the efflux of a broad range of xenobiotics of highly diverse structures. BCRP activity greatly influences drug distribution in vivo and is often associated with cancer multidrug resistance, which is observed in the case of both chemotherapy and photodynamic therapy. The set of ABCG2 substrates includes porphyrins and chlorins such as heme, hemin, protoporphyrin IX, chlorin e6, pheophorbide a, and their derivatives. Here we provide an evidence that magnesium- and zinc-substituted derivatives of pheophorbide a, which are very promising photosensitizers for use in photodynamic therapy, are also recognized and transported by ABCG2. Interestingly, despite minor structural differences, they clearly differ in the transport rate, both between each other and compared to pheophorbide a. In addition, their transport rate, like those of other structurally similar compounds, is strictly dependent on the level of serum albumin in the extracellular environment. The results that we present here are crucial for the use of metal-substituted pheophorbides in clinical practice but also provide an important insight into the mechanism of porphyrin transport by ABCG2.

Long-term albumin infusion in decompensated cirrhosis: A review of current literature

Decompensated cirrhosis is characterized by chronic inflammation and severe portal hypertension leading to systemic circulatory dysfunction. Albumin infusion has been widely used in decompensated cirrhosis in patients with spontaneous bacterial peritonitis, large-volume paracentesis and hepatorenal syndrome. Emerging data suggest long-term albumin infusion has both oncotic and non-oncotic properties which may improve the clinical outcomes in decompensated cirrhosis patients. We review the current literature on both the established and potential role of albumin, and specifically address the controversies of long-term albumin infusion in decompensated cirrhosis patients.

Women who develop ovarian cancer show an increase in serum calcium and a decrease in serum albumin. A longitudinal study in the Janus Serum Bank Cohort

Background.

Ovarian cancer is associated with high serum calcium and low serum albumin in clinical and epidemiologic studies. Whether high calcium and low albumin predispose to ovarian cancer or reflect existing cancer is unclear.

Objective.

Test the hypothesis that serum calcium increases and serum albumin decreases in women who develop ovarian cancer.

Methods.

Two hundred and four women donated sera to the Janus Serum Bank in Norway pre- and post-diagnosis of ovarian cancer, donations separated by approximately 14 years. We measured calcium and albumin in these sera and calculated the albumin-corrected calcium. Sera were adjusted for patient age and storage time.

Results.

Post-diagnosis, mean age- and storage-adjusted calcium increased, from 2.53 to 2.68 mmol/L (p < .001). Mean age- and storage-adjusted, albumin-corrected calcium increased from 2.3 to 2.7 mmol/L (p < .001). Conversely, mean age- and storage-adjusted albumin decreased, from a mean of 51.3 to 40.9 g/L (p < .001). Significant changes were observed in women with early stage and metastatic cancer.

Conclusions.

These data support the hypothesis that calcium and albumin are serum biomarkers of extant ovarian cancer. Longitudinal changes in calcium and albumin may be useful in ovarian cancer early detection.

Application of Fisetin to the Quantitation of Serum Albumin

Fisetin (3,3′,4′,7-tetrahydroxyflavone) is a widely distributed natural flavonol. It interacts with albumin, and thereby generates a fluorescence signal quantitatively. Based on such optical characteristics, we postulated that fisetin was applicable to the quantitation of albumin as an indicator. To establish the fisetin-based albumin assay, we examined the optical properties of fisetin and fisetin–albumin complex. The assay conditions were fine-tuned to fit for the actual concentration of serum albumin and to generate an optimal signal with a high signal-to-background ratio. The reaction between fisetin and albumin was linear in a wide range of concentrations. Non-protein serum components did not interfere with the reaction. The reactivity of fisetin was apparently specific for albumin among serum proteins. Both plasma and serum were compatible with the assay. The samples could be stored in a refrigerator or a freezer without the loss of reactivity toward fisetin. The generation and decay rates of the signal were acceptable for manual handling. The recovery of fortified albumin in serum was confirmed and the assay was validated with human sera. Fisetin-based albumin assay is suitable for clinical laboratory testing, considering the simple and short procedure, high specificity and sensitivity, linearity over a wide range of albumin concentrations, and, presumably, potential automatability.

Increased Ratio of Non-mercaptalbumin-1 Among Total Plasma Albumin Demonstrates Potential Protein Undernutrition in Adult Rats

The redox state of plasma albumin shifts in response to dietary protein intake in growing rats, and the shift is more sensitive than that of plasma albumin level, a classical marker of protein nutritional status. While it has been suggested that plasma albumin redox state could be useful as a novel marker of protein nutritional status, the above animal model is highly sensitive to dietary protein intake and the observation may not be extrapolated widely to humans. This study aimed to investigate whether albumin redox state also reflects protein nutritional status in adult rats, which have a lower dietary protein requirement and are less responsive to protein intake. Male adult rats were placed on AIN-93M diet (14% casein), or AIN-93M-based low protein diets (10 or 5% casein) ad libitum for 24 weeks. Whereas there was no significant difference in body weight between the groups at the end of the experimental period, the 5% casein diet group had the smallest gastrocnemius muscle weight among the groups, which was significantly lower than that of the 10% casein diet group. Plasma albumin level was also lower in the 5% casein diet group compared with the other groups, but the differences were limited and inconsistent during the experimental period. Among the albumin redox isoforms such as mercaptalbumin, non-mercaptalbumin-1, and non-mercaptalbumin-2, the ratio of non-mercaptalbumin-1 among total albumin was significantly higher in the 5% casein diet group, and the increase remained constant throughout the experimental period. Increased non-mercaptalbumin-1 ratio would thus demonstrate the presence of potential protein undernutrition in adult rats, as manifested only by a decreased gain in a specific type of skeletal muscle; non-mercaptalbumin-1 among total albumin ratio could be useful as a robust marker of protein nutritional status, contributing to prevention of protein undernutrition-related diseases such as frailty and sarcopenia.

New Insights About Albumin and Liver Disease

Decompensated liver cirrhosis has a dismal prognosis, with an overall survival of 2-4 years, which is worse than for many oncological diseases. Albumin is an important tool in the management of patients with cirrhosis, since it decreases for less than half the risk for post-paracentesis cardiocirculatory dysfunction and mortality associated with spontaneous bacterial infection, as well as, it triplicates the response to terlipressin in patients with hepatorenal syndrome. Recently, research on albumin has been a hot topic, with important new insights such as the characterization of the pleiotropic effects of albumin (which surpass its oncotic properties) and the concept of effective albumin concentration. In fact, patients with liver cirrhosis present posttranslational modifications on albumin that compromises its function. Those modified albumin forms were proved to have prognostic value and its knowledge may change the paradigm of albumin treatment. In this review, we critically summarize the latest evidence on the potential benefits of albumin in patients with end-stage liver disease.

THE SERUM PROTEIN FRACTIONS IN THYMOQUINONE TREATED RATS

Background:

TQ has been used as treatment and preventive agent for many diseases over the years. The goal of this study was to investigate the effects of TQ supplement on fractions of serum proteins.

Materials and methods:

Fourteen male Wistar-Albino rats (200-250 g weight) were used as material for two groups; (control (C) and thymoquinone (TQ) respectively. Each group contained seven rats. The control group had only corn oil, while the TQ group was dissolved in corn oil. 30 mg/kg/day were given by oral gavage for four weeks. The serum protein fractions were identified using cellulose acetate technique.

Results:

The total protein level and albumin, α-1, α-2 fractions and A/G ratio have showed no difference between groups (p>0.05). β-globulin fractions of TQ group were higher than control’s (p<0.05). In addition, it was observed that the γ-globulin levels of TQ group were lower than that of the control group’s (p<0.05).

Conclusion:

From the results, it was observed that the changes of these fractions may have originated from elevation or decline synthesis, or activities of containing proteins.

Nanoparticle-Based Mycosis Vaccine

Many diseases that were considered major affliction of mankind in the past have been successfully eradicated with introduction of appropriate vaccine strategies. In order to expedite new challenges coming up to deal with various infectious diseases, nano-particulate-based subunit vaccines seem to be the demand of ordeal. The nano-vaccines can find better scope for the diseases that were not rampant in the semi-advanced world few years back. For example in present-day circumstances that corroborate with advancement in the field of medical sciences in terms of cancer chemotherapy, organ transplantation, therapy of autoimmune diseases, etc.; along with prevalence of altogether unheard diseases such as HIV infection, people are at risk of infliction with many more pathogens. In this regard, development of an effective prophylactic strategy against many opportunistic infections primarily caused by fungal pathogens needs better understanding of host pathogen relation and role of active immunity against pathogenic fungi. In the present study, we have tried to decipher effectiveness of a nano-sized vaccine delivery system in imparting protection against fungal pathogens.

Metabolic profiles of cow's blood; a review

The term 'metabolic profile' refers to the analysis of blood biochemical parameters that are useful to assess and prevent metabolic and nutritional disorders in dairy herds. In the higher standards of milk production, the priority in modern breeding is keeping dairy cows in high lactation and healthy. The proper analysis, as well as control. of their feeding and metabolic status is immensely important for the health condition of the herd. The disproportion between the genetically determined ability for milk production and the limitations in improving the energy value of the ration may be the cause of metabolic disorders. Negative energy balance has a major impact on the body's hormonal balance and organ functions and mostly appears during transition periods: from 3 to 2 weeks prepartum until 2-3 weeks postpartum. The term 'transition' is used to underscore the important physiological, metabolic and nutritional changes occurring in this time. The manner in which these changes occur and how they are diagnosed and detected are extremely important, as they are closely related to clinical and subclinical postpartum diseases, lactation and reproductive performance - factors that significantly shape the profitability of production. Therefore the priority for intensive milk production is prevention of metabolic diseases and other disorders. It is the intent of this review to synthesize and summarize the information currently available on metabolic status and physiological changes in the cow's body that occur during lactation, as well as to discuss the interpretation of the results, which will be a useful diagnostic tool in nutritional evaluations of the dairy herd. © 2016 Society of Chemical Industry.

Adjustments of Protein Metabolism in Fasting Arctic Charr, Salvelinus alpinus

Protein metabolism, including the interrelated processes of synthesis and degradation, mediates the growth of an animal. In ectothermic animals, protein metabolism is responsive to changes in both biotic and abiotic conditions. This study aimed to characterise responses of protein metabolism to food deprivation that occur in the coldwater salmonid, Arctic charr, Salvelinus alpinus. We compared two groups of Arctic charr: one fed continuously and the other deprived of food for 36 days. We measured the fractional rate of protein synthesis (K_S) in individuals from the fed and fasted groups using a flooding dose technique modified for the use of deuterium-labelled phenylalanine. The enzyme activities of the three major protein degradation pathways (ubiquitin proteasome, lysosomal cathepsins and the calpain systems) were measured in the same fish. This study is the first to measure both K_S and the enzymatic activity of protein degradation in the same fish, allowing us to examine the apparent contribution of different protein degradation pathways to protein turnover in various tissues (red and white muscle, liver, heart and gills). K_S was lower in the white muscle and in liver of the fasted fish compared to the fed fish. There were no observable effects of food deprivation on the protease activities in any of the tissues with the exception of liver, where the ubiquitin proteasome pathway seemed to be activated during fasting conditions. Lysosomal proteolysis appears to be the primary degradation pathway for muscle protein, while the ubiquitin proteasome pathway seems to predominate in the liver. We speculate that Arctic charr regulate protein metabolism during food deprivation to conserve proteins.

EDTA-treated cotton-thread microfluidic device used for one-step whole blood plasma separation and assay

This study aims to observe the wicking and separation characteristics of blood plasma in a cotton thread matrix functioning as a microfluidic thread-based analytical device (μTAD). We investigated several cotton thread treatment methods using ethylenediaminetetraacetic acid (EDTA) anticoagulant solution for wicking whole blood samples and separating its plasma. The blood of healthy Indonesian thin tailed sheep was used in this study to understand the properties of horizontal wicking and separation on the EDTA-treated μTAD. The wicking distance and blood cell separation from its plasma was observed for 120 s and documented using a digital phone camera. The results show that untreated cotton-threads stopped the blood wicking process on the μTAD. On the other hand, the deposition of EDTA anticoagulant followed by its drying on the thread at room temperature for 10 s provides the longest blood wicking with gradual blood plasma separation. Furthermore, the best results in terms of the longest wicking and the clearest on-thread separation boundary between blood cells and its plasma were obtained using the μTAD treated with EDTA deposition followed by 60 min drying at refrigerated temperature (2-8 °C). The separation length of blood plasma in the μTADs treated with dried-EDTA at both room and refrigerated temperatures was not statistically different (P > 0.05). This separation occurs through the synergy of three factors, cotton fiber, EDTA anticoagulant and blood platelets, which induce the formation of a fibrin-filter via a partial coagulation process in the EDTA-treated μTAD. An albumin assay was employed to demonstrate the efficiency of this plasma separation method during a one-step assay on the μTAD. Albumin in blood is an important biomarker for kidney and heart disease. The μTAD has a slightly better limit of detection (LOD) than conventional blood analysis, with an LOD of 114 mg L(-1) compared to 133 mg L(-1), respectively. However, the μTAD performed faster to get results after 3 min compared to 14 min for centrifuged analysis of sheep blood samples. In conclusion, on-thread dried-EDTA anticoagulant deposition was able to increase the wicking distance and has a better capability to separate blood plasma and is suitable for combining separation and the assay system in a single device.

Serum Protein Thiol Levels in Patients with Hospital-Acquired Acute Kidney Injury

BACKGROUND/AIMS

This study aimed to examine antioxidants in patients with acute kidney injury (AKI) and determine whether serum protein thiol levels are associated with all-cause 90-day mortality in patients with hospital-acquired AKI.

METHODS

According to the RIFLE criteria, 160 patients with hospital-acquired AKI were enrolled in our prospective cohort study. As controls, 72 critically ill patients without AKI and 72 age and sex-matched healthy subjects were also recruited. Serum protein thiol levels were analyzed in relation to all-cause mortality of patients with AKI.

RESULTS

Serum protein thiol levels in AKI patients were lower than those in healthy people (p=0.010). Protein thiol levels showed a weak but significant positive correlation with serum albumin levels. The 90-day overall mortality rate was higher in AKI patients with high serum protein thiol levels than in those with low levels (p=0.032 by log rank test). In multivariate analysis (Cox regression), serum protein thiol levels (p=0.031) were independently associated with 90-day overall mortality after adjustment for age, sex, sepsis, and the Acute Physiology and Chronic Health Evaluation II score.

CONCLUSIONS

Patients with hospital-acquired AKI have remarkably low serum protein thiol levels. Elevated protein thiol levels are associated with 90-day overall mortality in hospital-acquired AKI.

The thiol pool in human plasma: the central contribution of albumin to redox processes

The plasma compartment has particular features regarding the nature and concentration of low and high molecular weight thiols and oxidized derivatives. Plasma is relatively poor in thiol-based antioxidants; thiols are in lower concentrations than in cells and mostly oxidized. The different thiol-disulfide pairs are not in equilibrium and the steady-state concentrations of total thiols as well as reduced versus oxidized ratios are maintained by kinetic barriers, including the rates of reactions and transport processes. The single thiol of human serum albumin (HSA-SH) is the most abundant plasma thiol. It is an important target for oxidants and electrophiles due to its reactivity with a wide variety of species and its relatively high concentration. A relatively stable sulfenic (HSA-SO3H) acid can be formed in albumin exposed to oxidants. Plasma increases in mixed disulfides (HSA-SSR) or in sulfinic (HSA-SO2H) and sulfonic (HSA-SO3H) acids are associated with different pathologies and may constitute biomarkers of the antioxidant role of the albumin thiol. In this work we provide a critical review of the plasma thiol pool with a focus on human serum albumin.

Intranasal administration of antiretroviral-loaded micelles for anatomical targeting to the brain in HIV

AIM

To investigate the intranasal administration of poly(ethylene oxide)-poly(propylene oxide) polymeric micelles loaded with high payloads of the first-line antiretroviral drug efavirenz for targeting to the CNS.

METHODS & MATERIALS

The effect of micellar size and composition and drug payload was assessed, employing simple micelles made of a highly hydrophilic copolymer, poloxamer F127, loaded with 20 mg/ml drug and mixed micelles containing 75% of a poloxamine of intermediate hydrophobicity, T904, and 25% F127 loaded with 20 and 30 mg/ml drug. F127 confers high physical stability, while T904 substantially improves the encapsulation capacity of the micelles.

RESULTS

The bioavailability of the drug in the CNS was increased fourfold and the relative exposure index (ratio between the area under the curve in the CNS and plasma) was increased fivefold with respect to the same system administered intravenously.

CONCLUSION

These findings demonstrate the potential of this scalable and cost-viable strategy to address the HIV sanctuary in the CNS.

Biomedical Applications of Biodegradable Polymers

Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. In order to fit functional demand, materials with desired physical, chemical, biological, biomechanical and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.

Avoiding nonspecific interactions in studies of the plasma proteome: practical solutions to prevention of nonspecific interactions for label-free detection of low-abundance plasma proteins

The molecular constitution of blood can be highly representative of the physiological state of an individual and offers an ideal target for studies of biomarkers. High-abundance plasma proteins, particularly albumin, dominate the plasma proteome, but it is the low-abundance proteins (such as cytokines) that are commonly associated with many pathophysiological states. Several detection strategies, and particularly those that involve label-free detection, are available for low-abundance protein detection in plasma, but all can be severely compromised by the high-abundance of serum albumin. In the present study, we examine the effect of albumin interference on accurate label-free detection by protein microarrays. Albumin was found to disrupt specific antigen-antibody binding interactions of low-abundance proteins. In clinical analysis, where it is imperative to preserve the integrity of samples, depletion of albumin may further undermine quantitative measurements. We have optimized procedures that permit accurate analysis to be undertaken without the need for prior treatment of samples. The emphasis is placed on disrupting nonspecific interactions including both electrostatic (i.e., Colulombic) and electrodynamic (hydrophobic and other nonpolar based) interactions. These protocols appear to be generic with potential applications in several areas of analytical biotechnology.

Serum albumin protects from cytokine-induced pancreatic beta cell death by a phosphoinositide 3-kinase-dependent mechanism

The present study was undertaken to investigate the biological activity of serum albumin when pancreatic beta cells were challenged by cytokines and pro-apoptotic reactive oxygen species like H(2)O(2). Culture of mouse islets or INS-1E beta cells for 24 h in the presence of H(2)O(2) (25 micromol/l) increased cell death. This demise was prevented by serum albumin, dependent on its free sulfhydryl group, emphasizing that albumin may scavenge H(2)O(2) due to its antioxidant properties. Culture for 48 h with a cytokine mixture of IL-1beta (160 pg/ml), IFN-gamma (200 ng/ml), and TNF-alpha (2 ng/ml) revealed that albumin, also protected against cytokine-induced death of both mouse islets and INS-1E beta cells. This protective effect against cytokine-induced beta cell death was, however, not dependent on albumins free sulfhydryl group, but was inhibited by the phosphoinositide 3-kinase (PI3K) inhibitors LY294002 (25 micromol/l) and wortmannin (1 micromol/l), suggesting that albumin may rescue beta cells from cytokine-induced cell death by activation of PI3K. In accordance, albumin stimulated phosphorylation of Akt, a down-stream target for PI3K. In conclusion, it is suggested that albumin may be a survival factor for pancreatic beta cells through scavenging of reactive oxygen species and by PI3K-dependent activation of Akt.

Predeposit autologous plasma donation in liver resection for hepatocellular carcinoma: toward allogenic blood-free operations

BACKGROUND

The aim of this study was to evaluate the safety of predeposit autologous plasma donation (PAPD) and its efficacy in avoiding allogenic blood transfusions and albumin infusion in liver resection for hepatocellular carcinoma.

STUDY DESIGN

PAPD was adopted in 20 patients in whom liver function remained within Child-Pugh's class A and an indocyanine green retention rate at 15 minutes was < or = 15% (PAPD group). Up to 1,200 mL of autologous fresh frozen plasma was collected through three blood donation sessions. Allogenic blood transfusion rates, albumin infusion rates, and postoperative courses were compared between the PAPD group and a historic control (no PAPD) group (n = 36).

RESULTS

Serum albumin levels after the last blood donation session were not significantly different from those before PAPD. The prothrombin activity even increased through the blood donation sessions (from median 80.9% [range 70.0% to 100%] to median 89.2% [range 71.2% to 100%]; p < 0.001). Allogenic blood transfusion rate and albumin infusion rate were lower in the PAPD group than in the no PAPD group (11% versus 75%; p < 0.001 and 16% versus 47%; p = 0.038, respectively). Wastage rate of the autologous fresh frozen plasma products was 9%.

CONCLUSIONS

PAPD was safe in patients with underlying liver disease and can be beneficial in simulating the liver synthetic function in advance of operation. Autologous fresh frozen plasma transfusion was effective for avoiding allogenic blood products in liver resection for hepatocellular carcinoma.

Controlling for Serum Albumin Level Improves the Correlation Between Serum Fatty Acid Ethyl Esters and Blood Ethanol Level

BACKGROUND

Fatty acid ethyl esters (FAEEs) are generated by the nonoxidative metabolism of alcohol and correlate positively with blood alcohol levels (BAL). As FAEEs are produced predominantly in the liver and bind to albumin in plasma, blood FAEE concentrations may be affected by serum albumin levels. The aim of this exploratory study was to define the relationship of FAEE levels with BAL after adjustment for serum albumin concentration.

METHODS

Fatty acid ethyl ester, BAL, and albumin concentrations were measured from de-identified, ethanol-containing serum samples (N=18). The assay focused on 3 FAEE species ethyl palmitate, ethyl stearate, and ethyl oleate. The relationships of individual and total FAEE concentrations with BAL using albumin as a covariate were analyzed. Values for Pearson's r between the BAL and the natural log-transformed FAEE (ln FAEE) levels were calculated, and then compared with partial correlation coefficients when controlling for albumin. The impact of serum albumin levels on the relationship between ln FAEE and BAL was evaluated by simple linear regression analysis.

RESULTS

Concentrations of total FAEE ranged from 632 to 20,166 nM, and BAL ranged from 9 to 375 mg/dL. In the 18 samples, the Pearson correlation coefficient between BAL and total FAEE levels was 0.868, and increased to 0.909 when controlling for albumin (p<0.0001). Similar statistically significant increases in the partial correlation coefficient occurred for each of the individual species of FAEE when controlling for albumin. In simple linear regression, albumin significantly reduced the variability in the model correlating BAL and FAEE for each of the individual species, as well as for total FAEE.

CONCLUSIONS

The association between FAEE levels and BAL is enhanced by consideration of serum albumin concentrations. Our findings suggest that serum albumin should be included in any model attempting to define the relationship between BAL and FAEE.

Investigation of an albumin-enriched fraction of human serum and its albuminome

The removal of albumin and other high abundance proteins is a routine first step in the analysis of serum and plasma proteomes. However, as albumin can bind proteins and peptides, there is a universal concern as to how the serum proteome is changed by the removal of albumin. To address this concern, the current study was designed to identify proteins and peptides removed from the serum during albumin depletion; to determine which of these are bound to albumin (rather than copurified) and whether the bound proteins are intact proteins or peptide fragments. Sequential, independent analyses including both anti-albumin antibody (anti-HSA) affinity chromatography and SEC were used to isolate albumin-bound proteins. RP-HPLC and 1-D SDS-PAGE were then used to further separate the proteins prior to identification by MS/MS. Finally, whole protein molecular weight (MW) MS measurements coupled with protein coverage obtained by MS were combined to assess whether the bound proteins were intact or peptide fragments. Combining the results from multiple approaches, 35 proteins, of which 24 are intact, were found to be associated with albumin, and they include both known high and low abundance proteins.

Albumin inhibits adipogenesis and stimulates cytokine release from human adipocytes

Bovine serum albumin (BSA) is commonly used in adipocyte experiments as a binding protein for fat-soluble substances. Therefore, it is of interest to investigate whether BSA per se is influencing the functioning of human adipocytes in vitro. In the present study, we investigated the potential of BSA to affect the proliferation and differentiation capacity of human preadipocytes. BSA was found to inhibit adipose differentiation in a dose-dependent manner (being significant at concentrations of 2.5 μM), whereas proliferation was not affected. We further investigated the effect of BSA on the secretory function of adipocytes focusing on the release of selected cytokines. Preadipocytes and freshly isolated adipocytes incubated with BSA secreted significantly higher amounts of IL-6, -8, and -10, and TNF-α compared with cells incubated without BSA. The effects on cytokine secretion seemed to reside at the level of gene expression because BSA increased TNF-α and IL-6 mRNA in a dose-dependent manner. The results of the present study indicate that the presence of BSA in the culture medium has considerable effects on adipocyte function in vitro. These effects should be carefully considered for in vitro studies of adipose tissue.