Inhibition of microvascular endothelial apoptosis in tissue explants by serum albumin

Prognostic Value of Serum Albumin Level in Critically Ill Patients: Observational Data From Large Intensive Care Unit Databases

Background

Decreased serum albumin level (SAL) is associated with adverse clinical outcomes. We designed the present study to further assess the prognostic value of SAL in critically ill patients based on data from large intensive care unit (ICU) databases.

Methods

This retrospective cohort study recruited 18,353 patients from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Restricted cubic splines (RCS) were performed to visualize the association of SAL at admission with ICU and hospital mortalities. The prognostic value of SAL was analyzed using logistic regression models and receiver operating characteristic (ROC) curves in overall patients and subgroups.

Results

Restricted cubic splines revealed rapid increasing risks in ICU and hospital mortalities when SAL declined to below 30 g/l. Patients with SAL <30 g/l (n = 6,069) had higher ICU (13.7% vs. 6.4%, p < 0.001) and hospital (23.9% vs. 10.7%, p < 0.001) mortalities than those with SAL ≥30 g/l. Multivariable logistic regression model revealed that SAL <30 g/l independently correlated with higher risks of both ICU (odds ratio [OR]: 1.20, 95% confidence interval [CI]: 1.07–1.36) and hospital (OR: 1.51, 95% CI: 1.37–1.66) mortalities. However, the association diminished in patients with cirrhosis (OR: 1.16, 95% CI: 0.91–1.49 for ICU mortality; OR: 1.21, 95% CI: 1.00–1.48 for hospital mortality). ROC curves revealed a poor performance of SAL in predicting mortalities, both in overall patients and in those with cirrhosis.

Conclusions

Decreased SAL is associated with increased risk of mortality. However, it possesses low sensitivity and specificity for outcome prediction in critically ill patients, especially in those with cirrhosis.

Albumin as a drug: its biological effects beyond volume expansion

Albumin is the most abundant and perhaps most important protein in human blood. Research has identified many of albumin's possible roles in modulating acid-base balance, modifying inflammation, maintaining vascular endothelial integrity, and binding endogenous and exogenous compounds. Albumin plays a key role in the homeostasis of vascular endothelium, offering protection from inflammation and damage to the glycocalyx. Albumin binds a diverse range of compounds. It transports, delivers and clears drugs, plus it helps with uptake, storage and disposal of potentially harmful biological products. The biological effects of albumin in critical illness are incompletely understood, but may enhance its clinical role beyond use as an intravenous fluid. In this article, we summarise the evidence surrounding albumin's biological and physiological effects beyond its use for plasma volume expansion, and explore potential mechanistic effects of albumin as a disease modifier in patients with critical illness.

Postoperative Course of Serum Albumin Levels and Organ Dysfunction After Liver Transplantation

BACKGROUND AND AIMS

Postoperative hypoalbuminemia, especially following liver transplantation, can lead to adverse multisystem effects and even death. We investigated the relationship between postoperative albumin levels and organ failure (assessed using Sequential Organ Failure Assessment [SOFA] scores).

METHODS

Sixty liver transplant recipients admitted to the intensive care unit (ICU) from 2012 to 2015 were retrospectively divided into 2 groups: lower albumin (LA) (n=28) and higher albumin (HA) (n=32), using whether serum albumin level fell below 3.0 g/dL during the first postoperative week as the stratifying factor. The SOFA scores (primary endpoint) and associated complications (ascites amount, rejection, re-intubation, abdominal re-operation, thrombosis), additional treatment (dialysis, pleural effusion drainage), and duration of ICU stay (secondary endpoints) of the 2 groups were compared.

RESULTS

Average serum albumin levels were significantly different between HA and LA groups (3.6 [3.4-3.8] vs 3.1 [2.9-3.3], respectively, P<.05), although the amounts of albumin infused in the 2 groups during the first postoperative week were not different (HA vs LA: 42 [30-71] vs 40 [30-58], respectively, P=.37). Mean daily SOFA scores were not significantly different between the HA and LA groups (8.3 [6.6-9.0] vs 7.2 [6.3-8.6], P=.73), although the HA group had lower mean cardiovascular SOFA sub-scores than the LA group (0.1 [0-0.4] vs 0.4 [0-1.3], P=.032). There were no significant differences between the groups with regard to complication rates and duration of ICU and hospital stays.

CONCLUSIONS

Serum albumin level might not influence cumulative organ function, but it decreases the amount of hemodynamic support required in liver transplant recipients.

Immunoproteomic identification and characterization of Ni2+-regulated proteins implicates Ni2+ in the induction of monocyte cell death

Nickel allergy is the most common cause of allergic reactions worldwide, with cutaneous and systemic effects potentially affecting multiple organs. Monocytes are precursors of not only macrophages but also dendritic cells, the most potent activators of nickel hypersensitivity. Monocytes are themselves important antigen-presenting cells, capable of nickel-specific T-cell activation in vivo and in vitro, in addition to being important for immediate innate immune inflammation. To elucidate early Ni²⁺-dependent inflammatory molecular mechanisms in human monocytes, a Ni²⁺-specific proteomic approach was applied. Quantitative two-dimensional (2D) differential gel electrophoresis and Delta2D software analyses coupled with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) revealed that Ni²⁺ significantly regulated 56 protein species, of which 36 were analyzed by MALDI-MS. Bioinformatics analyses of all identified proteins resulted in Ni²⁺-associated functional annotation clusters, such as cell death, metal ion binding, and cytoskeletal remodeling. The involvement of Ni²⁺ in the induction of monocyte cell death, but not T-cell death, was observed at Ni²⁺ concentrations at or above 250 μM. Examination of caspase activity during Ni²⁺-mediated cell death revealed monocytic cell death independent of caspase-3 and -7 activity. However, confocal microscopy analysis demonstrated Ni²⁺-triggered cytoskeletal remodeling and nuclear condensation, characteristic of cellular apoptosis. Thus, Ni²⁺-specific peripheral blood mononuclear cell stimulation suggests monocytic cell death at Ni²⁺ concentrations at or above 250 μM, and monocytic effects on immune regulation at lower Ni²⁺ concentrations.

Multifunctional Effect of Human Serum Albumin Reduces Alzheimer's Disease Related Pathologies in the 3xTg Mouse Model

Alzheimer's disease (AD), the prevalent dementia in the elderly, involves many related and interdependent pathologies that manifests simultaneously, eventually leading to cognitive impairment and death. No treatment is currently available; however, an agent addressing several key pathologies simultaneously has a better therapeutic potential. Human serum albumin (HSA) is a highly versatile protein, harboring multifunctional properties that are relevant to key pathologies underlying AD. This study provides insight into the mechanism for HSA's therapeutic effect. In vivo, a myriad of beneficial effects were observed by pumps infusing HSA intracerebroventricularly, for the first time in an AD 3xTg mice model. A significant effect on amyloid-β (Aβ) pathology was observed. Aβ1-42, soluble oligomers, and total plaque area were reduced. Neuroblastoma SHSY5Y cell line confirmed that the reduction in Aβ1-42 toxicity was due to direct binding rather than other properties of HSA. Total and hyperphosphorylated tau were reduced along with an increase in tubulin, suggesting increased microtubule stability. HSA treatment also reduced brain inflammation, affecting both astrocytes and microglia markers. Finally, evidence for blood-brain barrier and myelin integrity repair was observed. These multidimensional beneficial effects of intracranial administrated HSA, together or individually, contributed to an improvement in cognitive tests, suggesting a non-immune or Aβ efflux dependent means for treating AD.

Tooth eruption results from bone remodelling driven by bite forces sensed by soft tissue dental follicles: a finite element analysis

Intermittent tongue, lip and cheek forces influence precise tooth position, so we here examine the possibility that tissue remodelling driven by functional bite-force-induced jaw-strain accounts for tooth eruption. Notably, although a separate true 'eruptive force' is widely assumed, there is little direct evidence for such a force. We constructed a three dimensional finite element model from axial computerized tomography of an 8 year old child mandible containing 12 erupted and 8 unerupted teeth. Tissues modelled included: cortical bone, cancellous bone, soft tissue dental follicle, periodontal ligament, enamel, dentine, pulp and articular cartilage. Strain and hydrostatic stress during incisive and unilateral molar bite force were modelled, with force applied via medial and lateral pterygoid, temporalis, masseter and digastric muscles. Strain was maximal in the soft tissue follicle as opposed to surrounding bone, consistent with follicle as an effective mechanosensor. Initial numerical analysis of dental follicle soft tissue overlying crowns and beneath the roots of unerupted teeth was of volume and hydrostatic stress. To numerically evaluate biological significance of differing hydrostatic stress levels normalized for variable finite element volume, 'biological response units' in Nmm were defined and calculated by multiplication of hydrostatic stress and volume for each finite element. Graphical representations revealed similar overall responses for individual teeth regardless if incisive or right molar bite force was studied. There was general compression in the soft tissues over crowns of most unerupted teeth, and general tension in the soft tissues beneath roots. Not conforming to this pattern were the unerupted second molars, which do not erupt at this developmental stage. Data support a new hypothesis for tooth eruption, in which the follicular soft tissues detect bite-force-induced bone-strain, and direct bone remodelling at the inner surface of the surrounding bony crypt, with the effect of enabling tooth eruption into the mouth.

Fluid balance and colloid osmotic pressure in acute respiratory failure: optimizing therapy

Acute lung injury and acute respiratory distress syndrome continue to be major causes of morbidity and mortality in the intensive care unit due to a lack of specific effective therapy. Affecting nearly 200,000 people every year in the USA alone, patients with this syndrome often require extensive intensive care unit and hospital care, leading to enormous utilization of healthcare resources and significant expenditures, and ultimately leaving survivors with a reduced quality of life. A disease of altered capillary permeability, acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is characterized by significant fluid imbalances and oncotic pressure changes. Although investigations directed at these abnormalities may improve patient-centered outcomes, fluid management in ALI/ARDS continues to be a source of great controversy. In this review, we discuss fluid balance and the colloid osmotic pressure gradients in ALI/ARDS, followed by a review of the prognostic implications of increasing extravascular lung water, and conclude with contemporary approaches to optimizing therapy in this condition, including the role of albumin and diuretic therapy.

Comparison of microsuture, interpositional nerve graft, and laser solder weld repair of the rat inferior alveolar nerve

PURPOSE

Intraosseous repair of nerves involves difficulty of access and there is concern that bone healing may interfere with repair outcomes. The present report describes the effect of 3 separate repair techniques on recovery from section of the rat intraosseous inferior alveolar nerve, with reference to the mental nerve distal and the trigeminal ganglion proximal to the nerve section.

MATERIALS AND METHODS

Unilateral exposure of the inferior alveolar nerves of 28 rats was achieved through bone windows. Nerves were sectioned and rats were assigned to 1 of 4 groups (n = 7): untreated controls, microsuture repair, interpositional nerve grafts from the femoral nerve, or laser solder weld repair. Animals were sacrificed 1 year after surgery for histologic evaluation of the mental nerve, inferior alveolar nerve, and trigeminal ganglion compared with unoperated contralateral nerves.

RESULTS

Compared with the unoperated contralateral nerves, nerve section substantially decreased mental nerve fiber number, mental nerve myelination, mental nerve fiber diameter, inferior alveolar nerve vascularity, trigeminal neuron number, and trigeminal neuron horseradish peroxidase tracer uptake and increased trigeminal ganglion degenerate neurons (P < .001). All 3 forms of repair substantially decreased these effects (P < .05). Interpositional nerve graft was least effective (P < .05). Nonetheless, mental nerve fiber diameter was significantly decreased compared with unsectioned nerves after microsuture and laser solder weld repair (P < .05).

CONCLUSIONS

Intraosseous repair of the inferior alveolar nerve decreases peripheral and central signs of degeneration. Clinical hyperesthesia after repair may reflect a predominance of small fibers after recovery.

Alternative complement pathway assessment in patients with atypical HUS

The atypical Hemolytic Uremic Syndrome (aHUS) is a rare thrombotic microangiopathy leading to end stage renal disease in approximately 60% of patients. Over the last decade, a clear link has been demonstrated between this disease and defective complement regulation. The hallmark of the aHUS is the association with mutations in complement alternative pathway genes. Endothelial damage is related to complement dysregulation, but the exact mechanism is just starting to be elucidated. Screening for and characterization of mutations in the components of the C3 convertase (C3 and FB) or its regulators (FH, FI, MCP, and Thrombomodulin) or anti-FH antibodies has become an indispensable part of the disease's diagnostic. This review will initially summarize current knowledge on the understanding of complement activation and regulation, followed by a description on the genetic analysis as well as the methods used for complement protein quantification. Another part of this review will focus on the mechanisms of action of aHUS-associated mutations. We will emphasize on when and why some mutations lead to protein deficiency, while others result in - to dysfunctional but normally expressed proteins. Finally, we will discuss how the therapy of aHUS patients can be modified according to the functional consequences of each particular genetic defect.

Vascularity during wound maturation correlates with fragmentation of serum albumin but not ceruloplasmin, transferrin, or haptoglobin

Reduced vascularity during wound maturation is mediated by endothelial apoptosis. Albumin has an anti-apoptotic activity for endothelium, which increases up to 100-fold on albumin fragmentation (AF). We now report that levels of AF correlate with changing vascularity during wound maturation. Both scarring and adipogenic wound-healing models were established in mice. Western blots of granulation tissue revealed AF concurrent with periods of high vascularity as determined by thin-section microscopy, with reduced AF on wound maturation (p<0.02). In profiling AF, the levels of 27.5 and 39 kDa fragments were reduced on maturation of both scarring and adipogenic wounds (p<0.005), as were the levels of an additional 17.5 kDa fragment prominent only in adipogenic wounds (p<0.001). A 49 kDa albumin fragment was found to be reduced during maturation of scarring (p<0.001) but not adipogenic wounds. For comparison, we probed for transferrin, ceruloplasmin, and haptoglobin fragmentation on the basis that like albumin, these are considered acute-phase transport proteins. Minimal fragmentation of transferrin and ceruloplasmin was seen, along with partial dissociation of haptoglobin subunits, but these did not correlate with AF or vascularity. Our findings are consistent with a role for AF in regulating granulation tissue vascularity during healing.

The anti-apoptotic activity of albumin for endothelium is inhibited by advanced glycation end products restricting intramolecular movement

Human serum albumin (HSA) inhibits endothelial apoptosis in a highly specific manner. CNBr fragmentation greatly increases the effectiveness of this activity, suggesting that this type of protection is mediated by a partially cryptic albumin domain which is transiently exposed by intramolecular movement. Advanced glycation end-product (AGE) formation in HSA greatly reduces its intra-molecular movement. This study aimed to determine if this inhibits the anti-apoptotic activity of HSA, and if such inactivation could be reversed by CNBr fragmentation. HSA-AGE was prepared by incubating HSA with glucose, and assessed using the fructosamine assay, mass spectrometry, SDS-PAGE and fluorometry. Low levels of AGE in the HSA had little effect upon its anti-apoptotic activity, but when the levels of AGE were high and the intra-molecular movement was reduced, endothelial cell survival was also found to be reduced to levels equivalent to those in cultures without HSA or serum (p > 0.001). Survival was restored by the inclusion of native HSA, despite the presence of HSA with high levels of AGE. Also, CNBr fragmentation of otherwise inactive HSA-AGE restored the anti-apoptotic activity for endothelium. Apoptosis was confirmed by DNA gel electrophoresis, transmission electron microscopy and fluorescence-activated cell sorting analysis, and there was no evidence for direct toxicity in the HSA-AGE preparations. The results are consistent with the proposed role of intra-molecular movement in exposing the anti-apoptotic domain in HSA for endothelium. The levels of AGE formation required to inhibit the anti-apoptotic activity of HSA exceeded those reported for diabetes. Nonetheless, the data from this study seems to be the first example of reduced protein function due to AGE-restricted intra-molecular movement.

Polyethylene glycol modified-albumin enhances the cold preservation properties of University of Wisconsin solution in rat liver and a hepatocyte cell line

Liver grafts preserved in cold storage undergo changes mainly manifested by morphological modifications of the sinusoidal endothelium that result in poor graft function upon reperfusion. The present studies aimed to determine if the addition of polyethylene glycol-albumin to University of Wisconsin (Peg-AlbUW) solution ameliorates the cold preservation injuries of liver grafts. Rat livers were preserved cold with various preservation solutions and evaluated for weight changes and endothelial morphology. Solutions that preserved graft weight and endothelial morphology were tested in the isolated perfused rat liver model to assess graft function. A rat hepatocyte cell line was evaluated for both viability and glutathione concentrations emulating cold preservation and reperfusion conditions. Liver grafts preserved with Peg-AlbUW maintained their initial weight and showed a conserved endothelial morphology compared with liver grafts preserved in UW for 30 h (P<0.05). Liver grafts preserved with Peg-AlbUW had improved portal blood flow and bile secretion compared with liver grafts preserved in UW for 30 h (P<0.05). In vitro we noted comparable hepatocyte viability when cells were preserved in Peg-AlbUW versus UW under similar preservation conditions (P>0.05); glutathione concentrations (reduced and total) were significantly increased in hepatocytes preserved in 3% Peg-AlbUW compared with other preservation solutions (P<0.05). The addition of Peg-Alb to UW preservation solution ameliorated the cold preservation injuries of rat liver grafts as shown by stable liver graft weight, a better preservation of the endothelial morphology, improved portal vein blood flow, and increased bile secretion. Peg-Alb-UW solution improved the integrity of the glutathione redox buffer system of a hepatocyte cell line after cold storage and reperfusion.

Increased albumin concentration reduces apoptosis and improves functionality of human islets

Providing sufficient islet mass is important for successful islet transplantation. Apoptosis plays a major role in post-isolation islet cell death, and prevention of apoptosis could improve transplant outcomes. The purpose of this study was to determine whether increased concentration of human albumin (HA) in pre-transplantation culture of human islets would reduce apoptosis. Human islets were cultured in CMRL with 1.5 or 5% of HA for 24 h and apoptosis was evaluated indirectly by measuring caspase 3 activity and tetramethylrhodamine-ethyl-ester (TMRE) in dissociated islets. Islet function and viability were evaluated. Islets cultured in higher albumin concentration presented with lower caspase 3 activity (43.9 +/- 3.9 vs. 67.4 +/- 11.1, p = 0.011), and had increased insulin secretory capacity (Stimulation index 3.76 +/- 0.91 vs 1.23 +/- 0.21, p = 0.023). We conclude that an increase in albumin concentration can prevent apoptosis in isolated human islets. These findings may have implications for islet transplant outcomes.

The Anti-Apoptotic Activity of Albumin for Endothelium Is Mediated by a Partially Cryptic Protein Domain and Reduced by Inhibitors of G-Coupled Protein and PI-3 Kinase, but Is Independent of Radical Scavenging or Bound Lipid

Increased vascular disease occurs with low albumin (human serum albumin, HSA), possibly reflecting specific inhibition of endothelial apoptosis reported for tissue culture. Despite the reported specificity for endothelial protection by HSA, the high but physiological concentrations needed appear more consistent with non-specific low-affinity interactions. We reconcile this contradiction by demonstrating protection is mediated by a partially cryptic HSA protein domain, which becomes more exposed and active following cyanogen bromide fragmentation (p < 0.001). Also, although others reported HSA radical scavenging and bound lipids as important for inhibiting apoptosis in non-endothelial cell types, we demonstrate the protective effect for endothelium is unaffected when HSA radical scavenging is blocked by alkylation, or following delipidation. Further probing the mechanism responsible, we found that the G-coupled protein inhibitors pertussis toxin and suramin reduced protection of endothelium by HSA (p < 0.005), while the tyrosine kinase inhibitor genistein had no effect. Consistent with a role for phosphoinositide 3 kinase (PI3K) was inhibition by both wortmannin and LY294002 (p < 0.05), as well as phosphorylation of Akt, while MAP kinase inhibitors had no effect. We conclude the active site in HSA inhibiting endothelial apoptosis is partially cryptic, and acts via a G-coupled protein PI3K-dependent mechanism.

Albumin administration improves organ function in critically ill hypoalbuminemic patients: A prospective, randomized, controlled, pilot study

OBJECTIVE

To test the hypothesis that administration of albumin to correct hypoalbuminemia might have beneficial effects on organ function in a mixed population of critically ill patients.

DESIGN

: Prospective, controlled, randomized study.

SETTING

Thirty-one-bed, mixed medicosurgical department of intensive care.

PATIENTS

All adult patients with a serum albumin concentration < or =30 g/L were assessed for eligibility. Principal exclusion criteria were expected length of stay <72 hrs, life expectancy <3 months or a do-not-resuscitate order, albumin administration in the preceding 24 hrs, or evidence of fluid overload.

INTERVENTIONS

The 100 patients were randomized to receive 300 mL of 20% albumin solution on the first day, then 200 mL/day provided their serum albumin concentration was <31 g/dL (albumin group), or to receive no albumin (control group).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the effect of albumin administration on organ function as assessed by a delta Sequential Organ Failure Assessment score from day 1 to day 7 (or the day of intensive care discharge or death, whichever came first). The two groups of 50 patients were comparable at baseline for age, gender, albumin concentration, and Acute Physiology and Chronic Health Evaluation II score. Albumin concentration did not change over time in the control group but increased consistently in the albumin group (p < .001). Organ function improved more in the albumin than in the control group (p = .026), mainly due to a difference in respiratory, cardiovascular, and central nervous system components of the Sequential Organ Failure Assessment score. Diuretic use was identical in both groups, but mean fluid gain was almost three times higher in the control group (1679 +/- 1156 vs. 658 +/- 1101 mL, p = .04). Median daily calorie intake was higher in the albumin than in the control group (1122 [935-1158] vs. 760 [571-1077] kcal, p = .05).

CONCLUSIONS

Albumin administration may improve organ function in hypoalbuminemic critically ill patients. It results in a less positive fluid balance and a better tolerance to enteral feeding.

p38 MAPK activation coupled to endocytosis is a determinant of endothelial monolayer integrity

We show in rat lung microvessel endothelial cells (RLMVEC) that endocytosis is a critical determinant of activation of mitogen-activated protein kinase (MAPK) and thereby regulates endothelial monolayer integrity. In RLMVEC grown in serum-free medium, we observed that albumin supplementation induced the phosphorylation of p38 MAPK within 30 min, which persisted for up to 2 h. Engagement of the endocytic machinery regulated the activation of p38 MAPK that contributed to endothelial cell proliferation and reduction of apoptosis. We also observed an interaction between the caveolar protein caveolin-1 and p38 MAPK with reciprocal coimmunoprecipitation assays and colocalization using double-label immunofluorescence staining. Knockdown of caveolin-1 expression with small interfering RNA significantly reduced endocytosis and activation of p38 MAPK and interfered with the ability of endothelial cells to form a confluent monolayer. Thus caveolae-mediated endocytosis and concomitant activation of p38 MAPK may help to maintain endothelial monolayer integrity by signaling proliferation and survival of endothelial cells.

The relationship between albumin, other plasma proteins and variables, and age in the acute phase response after liver resection in man

A large series of plasma albumin (ALB, g/dl) and simultaneous blood and clinical measurements were prospectively performed on 92 liver resection patients, and processed to assess the correlations between ALB, other plasma proteins, additional variables and clinical events. The measurements were performed preoperatively and at postoperative day 1, 3 and 7 in all patients, and subsequently only in those who developed complications or died. In patients who recovered normally ALB was 4.3 +/- 0.4 g/dl (mean +/- SD) preoperatively, 3.7 +/- 0.7 at day 1 and 3, and 3.9 +/- 0.4 at day 7. In patients with complications its decrease was more prolonged. In non-survivors it was 3.4 +/- 0.4 preoperatively, 3.0 +/- 0.4 at day 1, and then decreased further. Regression analysis showed direct correlations between ALB and pseudo-cholinesterase (CHE, U/l, nv 5300-13000), cholesterol (CHOL, mg/dl), iron binding capacity (IBC, mg/dl), prothrombin activity (PA, % of standard reference) and fibrinogen, an inverse correlation with blood urea nitrogen (BUN, mg/dl) for any given creatinine level (CREAT, mg/dl), and weaker direct correlations with hematocrit, other variables and dose of exogenous albumin. An inverse relationship found between ALB and age (AGE, years) became postoperatively (POSTOP) also a function of outcome, showing larger age-related decreases in ALB associated with complications (COMPL: sepsis, liver insufficiency) or death (DEATH). Main overall correlations: CHE = 287.4(2.014)(ALB), r = 0.73; CHOL = 16.5(1.610)(ALB) (1.001)(ALKPH), r = 0.71; IBC = 68.6(1.391)(ALB), r = 0.64; PA = 13.8 + 16.0(ALB), r = 0.51; BUN = 21.3 + 20.2(CREAT) - 6.2(ALB), r = 0.91; ALB = 5.0-0.013(AGE) - {0.5 + 0.003(AGE)( COMPL ) + 0.012(AGE)( DEATH )}( POSTOP ), r = 0.74 [p < 0.001 for each regression and each coefficient; ALKPH = alkaline phosphatase, U/l, nv 98-279, independent determinant of CHOL; discontinuous variables in italics label the change in regression slope or intercept associated with the corresponding condition]. These results suggest that altered albumin synthesis (or altered synthesis unable to compensate for albumin loss, catabolism or redistribution) is an important determinant of hypoalbuminemia after hepatectomy. The correlations with age and postoperative outcome support the concept that hypoalbuminemia is a marker of pathophysiologic frailty associated with increasing age, and amplified by the challenges of postoperative illness.

Ultrastructural changes in endothelium during apoptosis indicate low microembolic potential

BACKGROUND

Apoptotic endothelium has been suggested to have microthrombotic and microembolic potential. While some describe pro-coagulant activities and platelet binding, others demonstrate maintained fibrinolytic protein and anti-platelet aggregatory activity. Canalicular fragmentation is unique to apoptotic endothelium and is suggested to facilitate size reduction of apoptotic cells to reduce microembolic potential. Despite the potential importance of apoptotic microemboli, there are no reports characterizing changes in cell size and shape during endothelial apoptosis.

METHODS

Here, we describe transmission and scanning electron microscopic studies of apoptotic endothelium and compare changes seen with apoptotic HL-60 cells incapable of canalicular fragmentation.

RESULTS

We demonstrate reduced endothelial size (p<0.05) with progressive apoptosis relative to apoptotic HL-60 cells. Mechanical stress accelerated size reduction of apoptotic endothelium(P< 0.01) but did not affect the size of apoptotic HL-60 cells. Mechanical stress also increased circularity in apoptotic endothelium (p<0.01), suggested to facilitate passage through small vessels. Earlier work indicated that canaliculi form through plasma membrane invagination, but we report fusion of small vesicles contributing to canalicular growth, while canaliculi fuse to form large vacuoles and also dilate at late stages of apoptosis.

CONCLUSIONS

These observations are consistent with the suggestion that endothelium is adapted to minimize microembolic potential and that canalicular fragmentation contributes to this.

Differential effects of serum constituents on apoptosis induced by the cyclopentenone prostaglandin 15-deoxy-delta12,14-prostaglandin J2 in WISH epithelial cells

Cyclopentenone prostaglandins, delta12-PGJ2 and 15d-PGJ2, have potent anti-tumour and anti-inflammatory activities, and have been shown to induce apoptosis in amnion-derived WISH cells. In this study, we have investigated the protective effects of serum and its constituents (growth factors and albumin) on delta12-PGJ2 and 15d-PGJ2-induced apoptosis in WISH cells. Serum (0.5% w/v) was protective against both delta12-PGJ2 and 15d-PGJ2-induced apoptosis. This was not due to the presence of serum-derived growth factors (EGF, IGF-1 and IGF-2), since they had no significant effect on 15d-PGJ2-induced cell death. In contrast, IGF-1 partially inhibited etoposide-induced apoptosis, confirming the presence of a functional IGF-1 receptor signalling system. Albumin was identified as the key survival factor in serum, since albumin and delipidated albumin exhibited the same level of protection from 15d-PGJ2-induced apoptosis as serum itself. The potential for serum albumin to regulate the bioactivity of cyclopentenone PGs may be of considerable importance in pathological conditions where roles for cyclopentenone PGs have been identified.

Albumin administration--what is the evidence of clinical benefit? A systematic review of randomized controlled trials

BACKGROUND AND OBJECTIVE

The advantages of albumin over less costly alternative fluids continue to be debated. Meta-analyses focusing on survival have been inconclusive, and other clinically relevant end-points have not been systematically addressed. We sought to determine whether albumin confers significant clinical benefit in acute illness compared with other fluid regimens.

METHODS

Database searches (MEDLINE, EMBASE, Cochrane Library) and other methods were used to identify randomized controlled trials comparing albumin with crystalloid, artificial colloid, no albumin or lower-dose albumin. Major findings for all end-points were extracted and summarized. A quantitative meta-analysis was not attempted.

RESULTS

Seventy-nine randomized trials with a total of 4755 patients were included. No significant treatment effects were detectable in 20/79 (25%) trials. In cardiac surgery, albumin administration resulted in lower fluid requirements, higher colloid oncotic pressure, reduced pulmonary oedema with respiratory impairment and greater haemodilution compared with crystalloid and hydroxyethylstarch increased postoperative bleeding. In non-cardiac surgery, fluid requirements, and pulmonary and intestinal oedema were decreased by albumin compared with crystalloid. In hypoalbuminaemia, higher doses of albumin reduced morbidity. In ascites, albumin reduced haemodynamic derangements, morbidity and length of stay and improved survival after spontaneous bacterial peritonitis. In sepsis, albumin decreased pulmonary oedema and respiratory dysfunction compared with crystalloid, while hydroxyethylstarch induced abnormalities of haemostasis. Complications were lowered by albumin compared with crystalloid in burn patients. Albumin-containing therapeutic regimens improved outcomes after brain injury.

CONCLUSIONS

Albumin can bestow benefit in diverse clinical settings. Further trials are warranted to delineate optimal fluid regimens, in particular indications.

Twenty-five percent albumin prevents lung injury following shock/resuscitation

OBJECTIVE

To evaluate novel indications for the use of human albumin solutions in the prevention and treatment of acute lung injury following shock/resuscitation and to test the hypothesis that 25% human albumin is an effective resuscitation fluid as well as an immunomodulatory agent protective against lung injury in our model.

DESIGN

A previously developed rodent model of acute lung injury in which resuscitated shock primes for increased lung injury in response to a small dose of intratracheal lipopolysaccharide.

SETTING

University-affiliated hospital.

SUBJECTS

Sprague Dawley rats weighing 300-350 g.

INTERVENTIONS

Animals were bled to a mean arterial pressure of 40 mm Hg and maintained in a shock phase for 1 hr. Animals then were resuscitated by transfusion of the shed blood plus an equal volume of Ringer's lactate or their shed blood plus 3 mL/kg volume of 25% albumin or their shed blood plus 15 mL/kg of 5% human albumin over a period of 2 hrs. To test for the possible role of 25% albumin as an antioxidant, we also performed resuscitation with Ringer's lactate supplemented with N-acetylcysteine or 25% albumin depleted of its antioxidant properties by N-ethylmaleimide. Mean arterial pressure was monitored continuously. One hour after resuscitation, 100 microg of lipopolysaccharide in 200 microL of saline was administered intratracheally.

MEASUREMENTS AND MAIN RESULTS

Resuscitation with 25% albumin significantly reduced transpulmonary protein flux, bronchoalveolar lavage fluid neutrophil counts, and the degree of histopathological injury compared with resuscitation with Ringer's lactate or 5% albumin. To delineate the underlying mechanism of this beneficial effect, the production of cytokine-induced neutrophil chemoattractant as well as nuclear translocation of its critical transcription factor nuclear factor-kappaB was measured. Both cytokine-induced neutrophil chemoattractant messenger RNA concentrations and nuclear factor-kappaB translocation were diminished following 25% albumin resuscitation. Furthermore, 25% albumin significantly decreased lipid peroxidation in plasma as measured by 8-isoprostane concentrations. N-ethylmaleimide modified 25% albumin, possessing lesser antioxidant activity, exhibited an attenuated protection from lung injury.

CONCLUSIONS

Resuscitation with 25% albumin attenuates lung injury in this rat model. The beneficial effect was due to reduced neutrophil sequestration. The antioxidant properties of the 25% albumin preparation appeared to be partially responsible for the effects observed. These studies suggest a novel role for 25% albumin as an anti-inflammatory agent in neutrophil-mediated diseases, such as acute respiratory distress syndrome.

Hypoalbuminemia in acute illness: is there a rationale for intervention? A meta-analysis of cohort studies and controlled trials

OBJECTIVE

To determine whether hypoalbuminemia is an independent risk factor for poor outcome in the acutely ill, and to assess the potential of exogenous albumin administration for improving outcomes in hypoalbuminemic patients.

SUMMARY BACKGROUND DATA

Hypoalbuminemia is associated with poor outcomes in acutely ill patients, but whether this association is causal has remained unclear. Trials investigating albumin therapy to correct hypoalbuminemia have proven inconclusive.

METHODS

A meta-analysis was conducted of 90 cohort studies with 291,433 total patients evaluating hypoalbuminemia as an outcome predictor by multivariate analysis and, separately, of nine prospective controlled trials with 535 total patients on correcting hypoalbuminemia.

RESULTS

Hypoalbuminemia was a potent, dose-dependent independent predictor of poor outcome. Each 10-g/L decline in serum albumin concentration significantly raised the odds of mortality by 137%, morbidity by 89%, prolonged intensive care unit and hospital stay respectively by 28% and 71%, and increased resource utilization by 66%. The association between hypoalbuminemia and poor outcome appeared to be independent of both nutritional status and inflammation. Analysis of dose-dependency in controlled trials of albumin therapy suggested that complication rates may be reduced when the serum albumin level attained during albumin administration exceeds 30 g/L.

CONCLUSIONS

Hypoalbuminemia is strongly associated with poor clinical outcomes. Further well-designed trials are needed to characterize the effects of albumin therapy in hypoalbuminemic patients. In the interim, there is no compelling basis to withhold albumin therapy if it is judged clinically appropriate.

Induction of contact-dependent endothelial apoptosis by osteosarcoma cells suggests a role for endothelial cell apoptosis in blood-borne metastasis

Although tumour cells are believed to migrate between endothelial cells early in metastasis, the possibility remains that endothelial apoptosis may also contribute to the tumour's breach of the vascular barrier. Although seemingly inconsistent with tumour angiogenesis, one publication describes the induction of contact-dependent apoptosis in cultured endothelium by tumour cells. The cell culture data are, however, open to challenge on technical grounds while there are no confirmatory reports. The present paper describes experiments overcoming these limitations. SAOS-2 human osteosarcoma cells and two rat carcinoma cell lines were co-cultured with human umbilical vein endothelial cells (HUVECs) and cultures labelled by surface lectin histochemistry for endothelium. The HUVEC culture density was determined and SAOS-2 cells, but not rat carcinoma cells, were found significantly to reduce HUVEC survival despite the release of potent growth factors as determined in separate experiments with tumour cell conditioned medium. Lectin labelling combined with light microscopy, transmission electron microscopy, flow cytometry for both lectin binding and DNA content, and DNA gel electrophoresis of SAOS-2/HUVEC co-cultures revealed extensive HUVEC apoptosis. These findings indicate contact-dependent endothelial apoptosis by SAOS-2, while this activity appeared weaker and overwhelmed by HUVEC proliferation with rat carcinoma cells. Importantly, this study supports the suggestion that endothelial apoptosis may be important for metastasis and suggests a complex interplay between endothelial proliferation and apoptosis in tumours.

Use of albumin in the intensive care unit

Recent publications have renewed interest in albumin use in the ICU. Meta-analyses have been published that demonstrate the safety of albumin administration and even potential benefits. Hypoalbuminemia, which has long been considered a marker of disease, has been causally linked to the development of complications. Finally, advances have been made in our knowledge of the unique and potentially beneficial properties of albumin.

Synergistic induction of apoptosis in human endothelial cells by tumour necrosis factor-alpha and transforming growth factor-beta

Serum deprivation stimulates endothelial apoptosis while albumin inhibits this and has been proposed as important in confining apoptotic remodelling to poorly perfused vessels. Tumour necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta are also reported to induce endothelial apoptosis. To investigate the comparative roles of these stimuli, the effect of TNF-alpha and TGF-beta, alone or in combination, in the presence or absence of serum or albumin was studied. There was strong synergy between the cytokines in inducing human umbilical vein endothelial cell apoptosis, but only in the absence of serum. Synergy was destroyed by boiling cytokines and was not affected by polymyxin B. Dose response experiments revealed greater activity of TGF-beta(1) than TGF-beta(2). The synergy was protein synthesis dependent and apoptosis was confirmed by DNA gel electrophoresis, transmission electron microscopy and FACS analysis. Data suggests a role for synergistic activation of endothelial cell apoptosis by TNF-alpha and TGF-beta(1) but perhaps only in poorly perfused vessels deprived of serum factors.

Adipogenic healing in adult mice by implantation of hollow devices in muscle

In mammals, wound healing is thought to result in the formation of scar tissue, with the exception of bony healing after fractures. Here we describe a previously unknown pattern of wound healing in which adipose rather than scar tissue is formed. Adipogenesis is normally confined to the embryo, although there are several experimental models for adipogenesis with highly specific dietary, cytokine, matrix, sex, or age requirements. The adipogenic healing described in this work provides a simple and reproducible experimental mouse model for adipogenesis without these limitations. Mice received intramuscular implants of nylon mesh material. Fibrinous material impregnated implants and within 4 weeks was replaced with highly vascular granulation tissue, typical of wound healing. Also consistent with wound healing was a reduction in vascularity of the newly formed tissue over time (P < 0.05). Lipoblasts were prevalent in granulation tissue, reaching a maximum in week 2 (P < 0.001) but falling to very low levels by week 9. These cells matured to adipocytes, with intermediate forms being seen. The identity of lipoblasts and adipocytes was confirmed by Oil Red O staining and electron microscopy. Control experiments confirmed that adipogenesis was independent of the materials used as well as of the sex and age of the animals. Rather, adipogenesis appeared to be due to replacement of fibrinous material in a space created within muscle. It is possible that adipogenic healing represents an adaptation for limiting the formation of restrictive scar tissues within muscle, and that this is the basis for the formation of traumatic lipomas in humans. Also, muscle tissue is replaced by adipose cells, seemingly derived from pluripotential satellite cells, in several degenerative muscle conditions, suggesting a role for adipogenic healing in these conditions.

Microvasculature in gingivitis and chronic periodontitis: disruption of vascular networks with protracted inflammation

Gingivitis occurring when bacterial plaque accumulates in the gingival crevice provides a convenient and interesting model for chronic inflammation in humans. In some patients, gingivitis progresses to the destructive lesion of periodontitis, involving the formation of periodontal pockets. The basis for pocket formation and progression is not as yet clear, although neutrophilic polymorphonuclear leukocytes (PMN) appear to play a protective role. Vascular changes appear to either facilitate or inhibit PMN function with the effect of either protecting from, or stimulating, periodontitis. Contrary to most circumstances, high endothelial cells in periodontitis are involved with PMN rather than lymphocyte emigration. Expansion of the microvasculature through increased vascular diameter and tortuosity as well as the development of high endothelial cells appears to protect from periodontitis by increasing the supply of both plasma defense factors and PMN to the tissues. Vascular changes that may oppose this and promote periodontitis are the formation of perivascular hyaline material and accumulation of basement membrane rests. The inadequate tissue turnover that accumulation of these vascular products represents can be argued as a vascular response to a chronic inflammation that has failed to eliminate the irritant. It is suggested that these vascular changes may account for the highly localized and burst-like pattern of pocket formation in periodontitis. Finally, it is possible that the recent observation that periodontitis is an independent risk factor for systemic vascular disease may reflect stimulation of acute phase protein synthesis by cytokines released by periodontal high endothelial cells.

Albumin-mediated regulation of cellular glutathione and nuclear factor kappa B activation

Human serum albumin (HSA) is a cystine-rich serum protein taken up by many cells through receptor-mediated and fluid-phase endocytosis. We hypothesized that HSA may play a role in modulating cellular antioxidant redox signaling. Lung epithelial cells (A549), fibroblasts (HFL1), and blood lymphocytes had increased glutathione (GSH) levels after 8 h incubation with HSA. Similar GSH increases were observed with either plasma-derived or recombinant HSA. Serum depleted of HSA had no effect on cellular GSH. The GSH increase was also observed in normal murine lungs upon in vivo airway instillation of HSA. GSH enhancement was not related to the redox state of the free cysteine residue (Cys-34) on HSA, however, reduction of disulfide bonds in HSA inhibited the increase in cellular GSH. In addition, the albumin-mediated increase in GSH was inhibited by the vacuolar (H(+))-ATPase inhibitors, bafilomycin A(1) and concanamycin, as well as by the membrane pH-disrupting ionophore monensin, but not by 20 mM NH(4)Cl. The degree to which albumin increased GSH levels was sufficient to protect cells against H(2)O(2)-mediated cytotoxicity and to decrease TNF-alpha-mediated NF-kappaB activation. We conclude that albumin specifically modulates cellular GSH levels, an effect sufficient to protect cells against oxidant injury and regulate NF-kappaB activation.