Release of proteins via ion exchange from albumin-heparin microspheres

Albumin-heparin and albumin microspheres were prepared as ion exchange gels for the controlled release of positively charged polypeptides and proteins. The adsorption isotherms of chicken egg and human lysozyme, as model proteins, on microspheres were obtained. An adsorption isotherm of chicken egg lysozyme on albumin-heparin microspheres was linear until saturation was abruptly reached,\ud \ud The adsorption isotherms of human lysozyme at low and high ionic strength were typical of adsorption isotherms of proteins on ion exchange gels. The adsorption of human lysozyme on albumin-heparin and albumin microspheres fit the Freundlich equation suggesting heterogeneous binding sites. This was consistent with the proposed multivalent, electrostatic interactions between human lysozyme and negatively charged microspheres. Scatchard plots of the adsorption processes of human lysozyme on albumin-heparin and albumin microspheres suggested negative cooperativity, while positive cooperativity was observed for chicken egg lysozyme adsorption on albumin-heparin microspheres.\ud \ud Human lysozyme loading of albumin-heparin microspheres was 3 times higher than with albumin microspheres, with long term release occurring via an ion exchange mechanism. Apparent diffusion coefficients of 2.1 × 10-1 and 3.9 × 10-11cm2/sec were obtained for the release of human lysozyme from albumin-heparin and albumin microspheres, respectively. The release was found to be independent of diffusion, since the rate determining step was likely an adsorption/desorption processes. An apparent diffusion coefficient of 4.1 × 10-12 cm2/sec was determined for the release of chicken egg lysozyme from albumin-heparin microspheres.\ud \ud Low release of the lysozymes from albumin-heparin microspheres was observed in deionized water, consistent with the proposed ion exchange release mechanism. Overall, albumin-heparin microspheres demonstrated enhanced ion exchange characteristics over albumin microspheres

PENGARUH PEMBERIAN SUPLEMENTASI SUPEROXIDE DISMUTASE (SOD) TERHADAP KADAR ALBUMIN SERUM PADA LANSIA

Background: Levels of serum albumin can be used as a predictor of morbidity and mortality in the elderly. Reduced serum albumin concentration can be caused by oxidative modification due to aging or insufficient protein intake. SOD as an enzymatic antioxidant might prevent oxidative stress so that albumin modification process can be inhibited. SOD supplementation was expected to increase serum albumin levels. Aim: Analyze the effect of SOD supplementation on elderly serum albumin level. Methods: This was a true experimental study with pre and post test control group design.. The study began with 31 elderly, resides in the “Pucang Gading Social Rehabilitation Unit”. They were divided into 2 groups. The control group (15 subjects), received placebo and exercise. The treatment group (16 subjects), received 250 IU SOD/day and exercise. Both treatments were done within 8 weeks, with twice a week exercise. Before and after treatment, levels of serum albumin were measured. Data normality was tested using Saphiro-wilk test. Data was analyzed by Paired-T-test if the distribution is normal, and using Wilcoxon test if the distribution is abnormal. Results: There were increases of serum albumin levels in both groups. Statistical test results showed a significant increase of serum albumin levels in the treatment group of 0.26 ± 0.33 mg/dL with p=0,007 (p0,05). Conclusion: 250 IU SOD/day supplementation for 8 weeks increase serum albumin levels in the elderly. Keywords: Albumin, elderly, aging, SO

Albumin uptake in human podocytes: a possible role for the cubilin-amnionless (CUBAM) complex

Abstract Albumin re-uptake is a receptor-mediated pathway located in renal proximal tubuli. There is increasing evidence of glomerular protein handling by podocytes, but little is known about the mechanism behind this process. In this study, we found that human podocytes in vitro are committed to internalizing albumin through a receptor-mediated mechanism even after exposure to low doses of albumin. We show that these cells express cubilin, megalin, ClC-5, amnionless and Dab2, which are partners in the tubular machinery. Exposing human podocytes to albumin overload prompted an increase in CUBILIN, AMNIONLESS and CLCN5 gene expression. Inhibiting cubilin led to a reduction in albumin uptake, highlighting its importance in this mechanism. We demonstrated that human podocytes are committed to performing endocytosis via a receptor-mediated mechanism even in the presence of low doses of albumin. We also disclosed that protein overload first acts on the expression of the cubilin-amnionless (CUBAM) complex in these cells, then involves the ClC-5 channel, providing the first evidence for a possible role of the CUBAM complex in albumin endocytosis in human podocytes

Ursodeoxycholic acid improves bilirubin but not albumin in primary biliary cirrhosis: further evidence for nonefficacy.

BACKGROUND/AIM: In randomised controlled trials (RCTs) of ursodeoxycholic acid (UDCA), although serum bilirubin is frequently reduced, its effect on disease progression and mortality is unclear. As serum albumin is an established independent prognostic marker, one might expect less deterioration of serum albumin values in a UDCA-treated group. We therefore modelled the typical evolution of serum bilirubin and albumin levels over time in UDCA-untreated patients and compared it with the observed levels in UDCA RCTs. METHODS: Multilevel modelling was used to relate the evolution of serum albumin to serum bilirubin and time since patient referral. For each considered RCT, the derived model was used to predict the relationship between final mean serum albumin and bilirubin concentration, adjusted for mean serum albumin at referral and followup duration. RESULTS: Five RCTs were eligible in terms of available data, of which two had long followup. In all trials, serum albumin did not significantly differ between UDCA- and placebo-treated patients, despite the UDCA effect on serum bilirubin. Therefore, there is no evidence over time for changes or maintenance of albumin levels for UDCA-treated patients above the levels predicted for placebo-treated patients. CONCLUSIONS: Our findings suggest that UDCA does not alter serum albumin in a way that is consistent with its effect on serum bilirubin. Therefore, reductions in serum bilirubin of UDCA-treated PBC do not parallel another validated and independent prognostic marker, further questioning the validity of serum bilirubin reduction with UDCA as a surrogate therapeutic marker

Enzyme-linked immunosorbent assay for urinary albumin at low concentrations

We describe an enzyme-linked immunosorbent assay (ELISA) for urinary albumin. It requires only commercially available reagents, can detect as little as 16 micrograms of albumin per liter, and analytical recovery ranges from 92 to 116%. The assay is simple, rapid, and inexpensive. Albumin excretion was 6.2 (SD 4.1) mg/24 h in healthy subjects (n = 40), 14.7 (SD 7.2) mg/24 h in albumin-test-strip-negative Type I diabetics (n = 11), and 19.7 (SD 16.2) mg/24 h in patients with essential hypertension (n = 12)

Influence of biological variations and sample handling on measured microalbuminuria in diabetic patients

Five immunochemical assays for determining low concentrations of albumin were investigated. These were a radioimmunoassay (RIA); turbidimetric immunoassays (TIA) both according to end-point measuring principle on a Cobas Fara and Hitachi 717 analysers, and according to kinetic measuring principle on a Turbitimer instrument; and a nephelometric immunoassay (NIA). All achieved the analytical goal necessary for optimal patient care. The correlations between the albumin concentrations measured with the different techniques were very good. In vitro glycation of albumin did not influence albumin concentrations measured by the five assays. Urine albumin excretion measured over 3 consecutie days showed considerable day-to-day variation. This was highest for spot-urine specimens and significantly lower for 24 h and timed-overnight samples. Variation of storage temperature (room temperature, 4°C, -20°C), time (up till 3 months), and pH (within the range pH 5-8) of the urine samples did not change significantly the measured albumin concentrations. Different sample preparations (vortex-mixing, centrifugation, and thawing) had no influence on the measured albumin concentration. In conclusion, a maximum standardization of the collection of timed-overnight urine samples for screening and 24 h urine sampels for confirmation of microalbuminuria during 3 consecutive days is more crucial than the choice of the immunological technique

Release of macromolecules from albumin-heparin microspheres

Hydrophilic microspheres based on albumin-heparin conjugates have been prepared as a macromolecular delivery system. The soluble albumin-heparin conjugate was synthesized and crosslinked in a water-in-oil emulsion with glutaraldehyde to form microspheres in the same manner as for albumin microsphere preparation. The microspheres were characterized in terms of their size and swelling properties. The loading of macromolecules into albumin-heparin microspheres was carried out concurrently and after microsphere preparation. FITC-dextran was applied as a model macromolecule. A higher loading content was achieved when loading was carried out concurrently with microsphere preparation than when loaded subsequently. Prolonged release of FITC-dextran from albumin-heparin microspheres was achieved and attributed to the high molecular weight of the macromolecule. The release of FITC-dextran was modulated by crosslinking density, loading content and the method of drug incorporation. Apparently, the mechanism of FITC-dextran release from albumin-heparin microspheres was dependent on the method of drug incorporation. For release of FITC-dextran from the microspheres, assuming negligible interactions, a diffusion coefficient of 1.7 × 10¿9 cm2/s was determined

No effect of albumin infusion on the prevention of hepatic encephalopathy after transjugular intrahepatic portosystemic shunt

Hepatic encephalopathy (HE) is a major problem in patients submitted to TIPS. Previous studies identified low albumin as a factor associated to post-TIPS HE. In cirrhotics with diuretic-induced HE and hypovolemia, albumin infusion reduced plasma ammonia and improved HE. Our aim was to evaluate if the incidence of overt HE (grade II or more according to WH) and the modifications of venous blood ammonia and psychometric tests during the first month after TIPS can be prevented by albumin infusion. Twenty-three patients consecutively submitted to TIPS were enrolled and treated with 1 g/Kg BW of albumin for the first 2 days after TIPS followed by 0,5 g/Kg BW at day 4th and 7th and then once a week for 3 weeks. Forty-five patients included in a previous RCT (Riggio et al. 2010) followed with the same protocol and submitted to no pharmacological treatment for the prevention of HE, were used as historical controls. No differences in the incidence of overt HE were observed between the group of patients treated with albumin and historical controls during the first month (34 vs 31 %) or during the follow-up (39 vs 48 %). Two patients in the albumin group and three in historical controls needed the reduction of the stent diameter for persistent HE. Venous blood ammonia levels and psychometric tests were also similarly modified in the two groups. Survival was also similar. Albumin infusion has not a role in the prevention of post-TIPS HE

The effect of the systemic inflammatory response on plasma vitamin 25 (OH) D concentrations adjusted for albumin

<b>Aim</b><p></p> To examine the relationship between plasma 25(OH)D, CRP and albumin concentrations in two patient cohorts.<p></p> <b>Methods</b><p></p> 5327 patients referred for nutritional assessment and 117 patients with critical illness were examined. Plasma 25 (OH) D concentrations were measured using standard methods. Intra and between assay imprecision was <10%.<p></p> <b>Result</b><p></p> In the large cohort, plasma 25 (OH) D was significantly associated with CRP (rs = −0.113, p<0.001) and albumin (rs = 0.192, p<0.001). 3711 patients had CRP concentrations ≤10 mg/L; with decreasing albumin concentrations ≥35, 25–34 and <25 g/l, median concentrations of 25 (OH) D were significantly lower from 35 to 28 to 14 nmol/l (p<0.001). This decrease was significant when albumin concentrations were reduced between 25–34 g/L (p<0.001) and when albumin <25 g/L (p<0.001). 1271 patients had CRP concentrations between 11–80 mg/L; with decreasing albumin concentrations ≥35, 25–34 and <25 g/l, median concentrations of 25 (OH) D were significantly lower from 31 to 24 to 19 nmol/l (p<0.001). This decrease was significant when albumin concentration were 25–34 g/L (p<0.001) and when albumin <25 g/L (p<0.001). 345 patients had CRP concentrations >80 mg/L; with decreasing albumin concentrations ≥35, 25–34 and <25 g/l, median concentrations of 25 (OH) D were not significantly altered varying from 19 to 23 to 23 nmol/l. Similar relationships were also obtained in the cohort of patients with critical illness.<p></p> <b>Conclusion</b><p></p> Plasma concentrations of 25(OH) D were independently associated with both CRP and albumin and consistent with the systemic inflammatory response as a major confounding factor in determining vitamin D status.<p></p&gt

Abnormal liver function tests in acute heart failure: relationship with clinical characteristics and outcome in the PROTECT study

Aims: Episodes of acute heart failure (AHF) unfavourably affect multiple organs, which may have an adverse impact on the outcomes. We investigated the prevalence and clinical consequences of abnormal liver function tests (LFTs) in AHF patients enrolled in the PROTECT study. Methods and results: The LFTs comprised serial assessment of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and albumin at baseline and during follow-up (daily until discharge, on days 7 and 14). The prevalence of abnormal LFTs (above upper limit of normal for AST and ALT or below lower limit of normal for albumin) was: at baseline AST 20%, ALT 12%, albumin 40%; and at day 14: AST 15%, ALT 9%, albumin 26%. Abnormal LFTs at baseline were associated with a higher risk of in-hospital death with odds ratios [95% confidence interval (CI)] of 3.5 (1.7–7.3) for AST, 3.9 (1.8–8.4) for ALT, and 2.8 (1.3–5.9) for albumin (all P < 0.01). Abnormal baseline and discharge LFTs had an unfavourable impact on 180-day mortality with hazard ratios (95% CI) for baseline AST, ALT, and albumin of 1.3 (1.0–1.7), 1.1 (1.0–1.2), 1.4 (1.1–1.8), respectively, and 1.5 (1.1–2.0), 1.5 (1.0–2.2), and 1.6 (1.2–2.1), for discharge AST, ALT, albumin, respectively (all P < 0.05). Analysis of LFTs trajectories (calculated as changes in LFTs over time) revealed that increasing AST and ALT on day 3 as well as decreasing albumin on day 4 were independent prognosticators of 180-day outcome (all P < 0.05). Conclusions: Abnormal LFTs are frequent in AHF at baseline and during hospital stay and predict worse outcomes. Whether this association is causal and what are the underlying mechanisms involved require further study