Showing papers on "Serum albumin published in 2001"

Patient Survival after Human Albumin Administration

Abstract: Overall, this meta-analysis of 55 studies detected no effect of albumin on mortality; any such effect may therefore be small. This finding supports the safety of albumin. The influence of methodolo...

Human Albumin Therapy of Acute Ischemic Stroke Marked Neuroprotective Efficacy at Moderate Doses and With a Broad Therapeutic Window

Abstract: Background and Purpose—We examined the neuroprotective efficacy of moderate-dose human albumin therapy in acute focal ischemic stroke and defined the therapeutic window after stroke onset, within which this therapy would confer neurobehavioral and histopathological neuroprotection. Methods—Sprague-Dawley rats were anesthetized with halothane/nitrous oxide and received 2-hour middle cerebral artery occlusion (MCAo) by a poly-l-lysine–coated intraluminal suture. Neurological status was evaluated during occlusion (60 minutes) and daily for 3 days after MCAo. In the dose-response study, human albumin doses of either of 0.63 or 1.25 g/kg or saline vehicle (5 mL/kg) were given intravenously immediately after suture removal. In the therapeutic window study, a human albumin dose of 1.25 g/kg was administered intravenously at 2 hours, 3 hours, 4 hours, or 5 hours after onset of MCAo. Three days after MCAo, brains were perfusion-fixed, and infarct volumes and brain swelling were determined. Results—Moderate-dose al...

Interaction of bovine serum albumin with anionic surfactants

Abstract: The effect of binding and conformational changes induced by anionic surfactants sodium dodecyl sulfate (SDS) and sodium octyl sulfate (SOS) on bovine serum albumin (BSA) have been studied using differential scanning calorimetry (DSC), circular dichroism (CD), fluorescence and UV spectroscopic methods. The denaturation temperature, van't Hoff enthalpy and calorimetric enthalpy of BSA in the presence of SDS and SOS and urea at pH 7 have been determined. The results indicate that SDS plays two opposite roles in the folding and stability of BSA. It acts as a structure stabiliser at a low molar concentration ratio of SDS/BSA and as a destabilizer at a higher concentration ratio as a result of binding of SDS to denatured BSA. The Brandts and Lin model has been used to simulate the results.

Nutritional and metabolic considerations in the etiology of nonalcoholic steatohepatitis.

Abstract: The aim of this study was to determine if a relationship exists between nonalcoholic steatohepatitis (NASH) and serum levels of free fatty acids, choline deficiency, or celiac disease. Forty-seven patients with liver biopsy proven NASH were enrolled. Total serum free fatty acids and anti-endomysial antibodies were determined in all patients, while plasma free and phospholipid-bound choline were determined in 29 patients. Total serum free fatty acid concentration correlated significantly with female gender and serum albumin concentration. Patients with severe fibrosis on liver biopsy had significantly greater serum concentration of free fatty acids than patients without severe fibrosis. Plasma free and phospholipid-bound choline levels were normal and no significant correlation was found between the concentration of plasma free or phospholipid bound choline, and the severity of liver damage. Only one of the 47 patients with NASH had a positive titer for the anti-endomysial antibody. In conclusion, increased serum concentrations of free fatty acids were found in NASH and were associated with development of more severe liver disease. Neither choline deficiency nor celiac sprue by anti-endomysial antibody testing was associated with NASH.

Dilution and redistribution effects of rapid 2-litre infusions of 0.9% (w/v) saline and 5% (w/v) dextrose on haematological parameters and serum biochemistry in normal subjects: a double-blind crossover study

Abstract: Although hypoalbuminaemia after injury may result from increased vascular permeability, dilution secondary to crystalloid infusions may contribute significantly. In this double-blind crossover study, the effects of bolus infusions of crystalloids on serum albumin, haematocrit, serum and urinary biochemistry and bioelectrical impedance analysis were measured in healthy subjects. Ten male volunteers received 2-litre infusions of 0.9% (w/v) saline or 5% (w/v) dextrose over 1 h; infusions were carried out on separate occasions, in random order. Weight, haemoglobin, serum albumin, serum and urinary biochemistry and bioelectrical impedance were measured pre-infusion and hourly for 6 h. The serum albumin concentration fell in all subjects (20% after saline; 16% after dextrose) by more than could be explained by dilution alone. This fall lasted more than 6 h after saline infusion, but values had returned to baseline 1 h after the end of the dextrose infusion. Changes in haematocrit and haemoglobin were less pronounced (7.5% after saline; 6.5% after dextrose). Whereas all the water from dextrose was excreted by 2 h after completion of the infusion, only one-third of the sodium and water from the saline had been excreted by 6 h, explaining its persistent diluting effect. Impedances rose after dextrose and fell after saline (P<0.001). Subjects voided more urine (means 1663 and 563 ml respectively) of lower osmolality (means 129 and 630 mOsm/kg respectively) and sodium content (means 26 and 95 mmol respectively) after dextrose than after saline (P<0.001). While an excess water load is excreted rapidly, an excess sodium load is excreted very slowly, even in normal subjects, and causes persistent dilution of haematocrit and serum albumin. The greater than expected change in serum albumin concentration when compared with that of haemoglobin suggests that, while dilution is responsible for the latter, redistribution also has a role in the former. Changes in bioelectrical impedance may reflect the electrolyte content rather than the volume of the infusate, and may be unreliable for clinical purposes.

Effect of Oxidative Stress on the Structure and Function of Human Serum Albumin

Abstract: Purpose. Human serum albumin (HSA) was mildly oxidized by a metal–catalyzed oxidation system (MCO–HSA), chloramine–T (CT–HSA) or H2O2 (H2O2–HSA), and the effects of these treatments on the structural, drug–binding and esterase–like properties were studied. Methods. Protein conformation was examined by calorimetric, chromatographic, electrophoretic and spectroscopic techniques. Drug binding was studied by ultrafiltration method, and esterase–like activity was determined using p–nitrophenyl acetate as a substrate. Results. Far–UV and near–UV CD spectra indicated that significant structural changes had occured as the result of treatment with MCO–HSA and CT–HSA but not with H2O2–HSA. However, SDS–PAGE analysis does not provide precise information on gross conformational changes such as fragmentation, cross–linking and SDS–resistant polymerisation. The results of differential scanning calorimetry, the fluorescence of the hydrophobic probe 1,1–bis–4–anilino–naphthalene–5,5–sulfonic acid and the elution time from a hydrophobic HPLC column indicated that MCO–HSA and CT–HSA in particular, have a more open structure and a higher degree of exposure of hydrophobic areas than unoxidized HSA. In all cases, high–affinity binding of warfarin remained unchanged for all the oxidized HSAs. However, high–affinity binding of ketoprofen to CT–HSA and, especially, MCO–HSA was diminished. In addition, the esterase–like activity of these proteins were all decreased to the same low level. Conclusions. Mild oxidation of HSA has no detectable effect on the binding of drugs to site I in subdomain IIA. In contrast, both the ligand binding property of site II and the esterase–like activity of oxidized HSAs are decreased, most probably due to conformational changes in subdomain IIIA.

Effect of ibuprofen and warfarin on the allosteric properties of haem-human serum albumin. A spectroscopic study.

Abstract: Haem binding to human serum albumin (HSA) endows the protein with peculiar spectroscopic properties. Here, the effect of ibuprofen and warfarin on the spectroscopic properties of ferric haem-human serum albumin (ferric HSA-haem) and of ferrous nitrosylated haem-human serum albumin (ferrous HSA-haem-NO) is reported. Ferric HSA-haem is hexa-coordinated, the haem-iron atom being bonded to His105 and Tyr148. Upon drug binding to the warfarin primary site, the displacement of water molecules--buried in close proximity to the haem binding pocket--induces perturbation of the electronic absorbance properties of the chromophore without affecting the coordination number or the spin state of the haem-iron, and the quenching of the 1H-NMR relaxivity. Values of Kd for ibuprofen and warfarin binding to the warfarin primary site of ferric HSA-haem, corresponding to the ibuprofen secondary cleft, are 5.4 +/- 1.1 x 10(-4) m and 2.1 +/- 0.4 x 10(-5) m, respectively. The affinity of ibuprofen and warfarin for the warfarin primary cleft of ferric HSA-haem is lower than that reported for drug binding to haem-free HSA. Accordingly, the Kd value for haem binding to HSA increases from 1.3 +/- 0.2 x 10(-8) m in the absence of drugs to 1.5 +/- 0.2 x 10(-7) m in the presence of ibuprofen and warfarin. Ferrous HSA-haem-NO is a five-coordinated haem-iron system. Drug binding to the warfarin primary site of ferrous HSA-haem-NO induces the transition towards the six-coordinated haem-iron species, the haem-iron atom being bonded to His105. Remarkably, the ibuprofen primary cleft appears to be functionally and spectroscopically uncoupled from the haem site of HSA. Present results represent a clear-cut evidence for the drug-induced shift of allosteric equilibrium(a) of HSA.

The Value of Serum Albumin and High-Density Lipoprotein Cholesterol in Defining Mortality Risk in Older Persons with Low Serum Cholesterol

Abstract: OBJECTIVES: To investigate the relationship between low cholesterol and mortality in older persons to identify, using information collected at a single point in time, subgroups of persons with low and high mortality risk DESIGN: Prospective cohort study with a median follow-up period of 49 years SETTINGS: East Boston, Massachusetts; New Haven, Connecticut; and Iowa and Washington counties, Iowa PARTICIPANTS: Four thousand one hundred twenty-eight participants (64% women) age 70 and older at baseline (mean 787 years, range 70–103); 393 (95%) had low cholesterol, defined as ≤160 mg/dl MEASUREMENTS: All-cause mortality and mortality not related to coronary heart disease and ischemic stroke RESULTS: During the follow-up period there were 1,117 deaths After adjustment for age and gender, persons with low cholesterol had significantly higher mortality than those with normal and high cholesterol Among subjects with low cholesterol, those with albumin> 38 g/L had a significant risk reduction compared with those with albumin ≤38 g/L (relative risk (RR) = 057; 95% confidence interval (CI) = 041–079) Within the higher albumin group, high-density lipoprotein cholesterol (HDL-C) level further identified two subgroups of subjects with different risks; participants with HDL-C <47 mg/dl had a 32% risk reduction (RR = 068; 95% CI = 047–099) and those with HDL-C ≥47 mg/dl had a 62% risk reduction (RR = 038; 95% CI = 020–068), compared with the reference category; those with albumin ≤38 g/L and HDL-C <47 mg/dl CONCLUSIONS: Older persons with low cholesterol constitute a heterogeneous group with regard to health characteristics and mortality risk Serum albumin and HDL-C can be routinely used in older patients with low cholesterol to distinguish three subgroups with different prognoses: (1) high risk (low albumin), (2) intermediate risk (high albumin and low HDL-C), and (3) low risk (high albumin and high HDL-C)

Hepatic Uptake and Gene Expression Mechanisms following Intravenous Administration of Plasmid DNA by Conventional and Hydrodynamics-Based Procedures

Abstract: Hepatic uptake and gene expression mechanisms following intravenous administration of naked plasmid DNA (pDNA) by conventional and hydrodynamics-based procedures were studied in mice. After conventional (normal) intravenous injection, (32)P-labeled pDNA was rapidly eliminated from the circulation and predominantly taken up by the liver nonparenchymal cells while no significant gene expression was observed in this organ. The hepatic uptake process was saturable. Involvement of a specific mechanism was demonstrated since the hepatic uptake of [(32)P]pDNA was dramatically inhibited by cold pDNA, calf thymus DNA, and some polyanions [polyinosinic acid (poly I), dextran sulfate], but not by others (polycytidylic acid, chondroitin sulfate). The liver endothelial cells appeared to be a major contributor because gadolinium chloride (GdCl(3))-induced Kupffer cell blockade did not affect the hepatic uptake. After intravenous injection of naked pDNA with a large volume of saline at a high velocity (hydrodynamics-based procedure), the apparent hepatic uptake profile was similar to that after normal injection. The hepatic uptake was not inhibited by prior administration of polyanions, including poly I, dextran sulfate, and heparin. The hydrodynamics-based procedure resulted in marked gene expression in the liver, which was not inhibited by prior administration of polyanions or GdCl(3) treatment. These results indicate that pDNA uptake is a nonspecific process. This hypothesis was supported by the finding that significant hepatic uptake of bovine serum albumin and immunoglobulin G was observed after the hydrodynamics-based procedure.

Impact of preferential interactions on thermal stability and gelation of bovine serum albumin in aqueous sucrose solutions.

Abstract: The influence of sucrose (0--40 wt %) on the thermal denaturation and gelation of bovine serum albumin (BSA) in aqueous solution has been studied. The effect of sucrose on heat denaturation of 1 wt % BSA solutions (pH 6.9) was measured using ultrasensitive differential scanning calorimetry. The unfolding process was irreversible and could be characterized by a denaturation temperature (T(m)), activation energy (E(A)), and pre-exponential factor (A). As the sucrose concentration increased from 0 to 40 wt %, T(m) increased from 72.9 to 79.2 degrees C, E(A) decreased from 314 to 289 kJ mol(-1), and ln(A/s(-1)) decreased from 104 to 94. The rise in T(m) was attributed to the increased thermal stability of the globular state of BSA relative to its native state because of differences in their preferential interactions with sucrose. The change in preferential interaction coefficient (Delta Gamma(3,2)) associated with the native-to-denatured transition was estimated. The dynamic shear rheology of 2 wt % BSA solutions (pH 6.9, 100 mM NaCl) was monitored as they were heated from 30 to 90 degrees C, held at 90 degrees C for either 15 or 120 min, and then cooled to 30 degrees C. Sucrose increased the gelation temperature due to thermal stabilization of the native state of the protein. The complex shear modulus (G) of cooled gels decreased with sucrose concentration when they were held at 90 degrees C for 15 min because the fraction of irreversibly denatured protein decreased. On the other hand, G of cooled gels increased with sucrose concentration when they were held at 90 degrees C for 120 min because a greater fraction of irreversibly denatured protein was formed and the strength of the protein-protein interactions increased.

Regulation of endothelin‐1 and transforming growth factor‐β1 production in cultured proximal tubular cells by albumin and heparan sulphate glycosaminoglycans

Abstract: Background Both endothelin-1 (ET-1) and transforming growth factor beta 1 (TGF-beta1) have been implicated in the progression of interstitial fibrosis. In the present study we enquired if albumin influences the production of these factors in cultured human proximal tubular epithelial cells (PTEC) and if heparan sulphate glycosaminoglycans (HS-GAG) can inhibit this production. Methods ET-1 and TGF-beta1 production in supernatants of PTEC was measured by RIA and ELISA respectively. In addition semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) was performed to study differences in ET-1 and TGF-beta1 mRNA expression. To demonstrate ET-1 or TGF-beta1 binding to heparin or HS-GAG, binding studies by means of dot blot analysis were carried out. Results TGF-beta1 and ET-1 were both produced in different concentrations, depending on the PTEC culture tested. Human serum albumin (HSA) up-regulated the production of both factors in a time and dose dependent fashion. The production of these factors was inhibited by heparin under basal and stimulatory conditions. ET-1 production was only inhibited by HS-GAG with a high degree of sulphation. For the inhibition of TGF-beta1 production, the sulphation of HS-GAG was less critical. TGF-beta1, but not ET-1 mRNA expression was inhibited by HS-GAG. Inhibition of sulphation of cell surface HS-GAG resulted in the inhibition of ET-1 but not TGF-beta1 production. Both factors were able to bind to HS-GAG, although this required different amounts of HS-GAG sulphation for each factor. Conclusions Our data demonstrate that in PTEC the release of pro-fibrogenic factors can be inhibited by HS-GAG. This may explain to some extent the beneficial effect of heparin in the treatment of interstitial fibrosis.

Immunological Detection of a Novel Advanced Glycation End-Product

Abstract: The advanced stage of the Maillard reaction that leads to the formation of advanced glycation end-products (AGEs) plays an important role in the pathogenesis of angiopathy in diabetic patients and in the aging process. Recently, it has been proposed that the intermediates contributing to AGE formation include dicarbonyl intermediates such as glyoxal, methylglyoxal, and 3-deoxyglucosone (3-DG). In the present study, we developed a novel, non-carboxymethyllysine (CML) anti-AGE antibody that recognizes serum proteins and peptides modified by 3-DG in vivo. AGE-modified serum albumins were prepared by incubation of rabbit serum albumin with 3-DG or D-glucose. After immunization of rabbits, anti-AGE antisera were subjected to affinity chromatography on a Sepharose 4B column coupled with CML-BSA, or AGE-BSA created by incubation with 3-DG (AGE-6) or D-glucose (AGE-1). The AGE-Ab-6 and AGE-Ab-1 thus obtained was used to investigate AGEs in serum from diabetic patients on hemodialysis. Characterization of the novel AGE-Ab-6 obtained by immunoaffinity chromatography was performed with a competitive ELISA and immunoblot analysis. This antibody specifically cross-reacted with proteins modified by 3-DG. AGE-6 was detected in diabetic serum as three peaks with apparent molecular weights of 200, 1.15, and 0.85 kD, while AGE-1 was detected as four peaks with apparent molecular weights of 200, 65, 1.15, and 0.85 kD. This study provides new data on the pathways of AGE formation from 3-DG and methods for the immunochemical detection of AGEs. We also provide immunochemical evidence for the existence of six distinct AGEs in vivo among the AGE-modified proteins and peptides in the serum of diabetic patients on hemodialysis.

Rational design of diflunisal analogues with reduced affinity for human serum albumin.

Abstract: Many lead compounds bind to serum albumin and exhibit markedly reduced efficacy in vivo as compared to their potency in vitro. To aid in the design of compounds with reduced albumin binding, we performed nuclear magnetic resonance (NMR) structural and binding studies on the complex between domain III of human serum albumin (HSA-III) and diflunisal, a cyclooxygenase inhibitor with antiinflammatory activity. The structural studies indicate that the aromatic rings of diflunisal are involved in extensive and specific interactions with hydrophobic residues that comprise the binding pocket in subdomain IIIA. The carboxylic acid of diflunisal forms electrostatic interactions with the protein similar to those observed in the X-ray structure of HSA complexed to myristic acid. In addition to the structural studies, NMR-derived binding constants were obtained for diflunisal and closely related analogues to develop a structure-affinity relationship for binding to subdomain IIIA. On the basis of the structural and binding data, compounds were synthesized that exhibit more than a 100-fold reduction in binding to domain III of HSA, and nearly a 10-fold reduction in affinity for full length albumin. Significantly, several of these compounds maintain activity against cyclooxygenase-2. These results suggest a rational strategy for designing out albumin binding in potential drug molecules by using structure-based design in conjunction with NMR-based screening.

Clinical, Virologic, and Pathologic Significance of Elevated Serum Alpha-fetoprotein Levels in Patients with Chronic Hepatitis C

Abstract: Elevated serum alpha-fetoprotein (AFP) in patients with chronic hepatitis C is not uncommonly seen, but the pathogenesis of this phenomenon remains unclear. The aims of this study were to assess the prevalence of elevated serum AFP in patients with chronic hepatitis C and to evaluate the clinical, virologic, and histopathologic significance of this phenomenon. One hundred and fifteen Chinese patients with a histologic diagnosis of chronic hepatitis C were enrolled. None had evidence of hepatocellular carcinoma by image study at enrollment and for at least 2 years' follow-up. Of the 115 patients, 33 (29%) had elevated serum AFP (more than 12 ng/mL). There was a significantly lower mean serum albumin (4.0 +/- 0.1 vs. 4.3 +/- 0.1 gm/dL, p <0.001) and higher mean scores for periportal necroinflammation (3.3 +/- 0.3 vs. 2.3 +/- 0.2, p = 0.007) and fibrosis (2.3 +/- 0.2 vs. 1.1 +/- 0.1, p < 0.001) in patients with elevated serum AFP when compared with patients without elevated serum AFP. Patients with elevated serum AFP had significantly more incidences of genotype 1b infection when compared with patients without elevated serum AFP (77% vs. 51%, p = 0.021). Mean serum hepatitis C virus (HCV) RNA titer showed no significant difference between the two groups. Multivariate logistic regression analysis showed that as serum albumin of less than 4.2 gm/dL, a histology fibrotic score of more than 3, and HCV genotype 1b infection were significantly independent predictors associated with elevated serum AFP. In conclusion, elevated serum AFP levels were significantly correlated with lower serum albumin levels, advanced fibrosis/cirrhosis, and genotype 1b infection in patients with chronic hepatitis C.

Effects of Albumin/Furosemide Mixtures on Responses to Furosemide in Hypoalbuminemic Patients

Abstract: Hypoalbuminemic patients often have sufficient fluid accumulation to mandate diuretic therapy but are often resistant to diuresis. Studies have suggested that hypoalbuminemia itself impairs delivery of effective amounts of diuretic agent into the urine, the site of action. Therefore, administration of mixtures of albumin and loop diuretics may enhance responses. Thirteen patients with biopsy-proven cirrhosis and ascites (age, 51.2 +/- 8.1 yr; Child-Pugh score, 8.5 +/- 1.0; serum albumin concentration, 3.0 +/- 0.6 g/dl) were studied in this randomized crossover study. Sodium balance was maintained throughout the study with a metabolic diet. All patients received spironolactone, but administration of all other diuretic agents was discontinued. Each patient received all of the following four treatments intravenously: (1) 40 mg of furosemide, (2) 25 g of albumin, (3) 40 mg of furosemide and 25 g of albumin premixed ex vivo, and (4) 40 mg of furosemide and 25 g of albumin infused simultaneously into different arms. Responses were assessed by measuring urinary sodium excretion and relating the urinary furosemide excretion rate to the sodium excretion rate. Additionally, the pharmacokinetics of furosemide were assessed. Furosemide pharmacokinetics were similar for all treatment arms. Albumin alone had negligible diuretic effects. Neither albumin regimen increased the response to furosemide. Moreover, the relationship between the urinary furosemide excretion rate and the sodium excretion rate was unaffected by albumin. In conclusion, albumin failed to enhance the diuretic effects of furosemide in cirrhotic patients with ascites. Therefore, the coadministration of albumin and furosemide for the treatment of cirrhosis, and likely other hypoalbuminemic conditions, should not be used clinically.

Characteristics of the hepatic stellate cell-selective carrier mannose 6-phosphate modified albumin (M6P(28)-HSA).

Abstract: Background/Aims: Drug targeting to hepatic stellate cells (HSC) may improve the pharmacological effects of antifibrotic drugs. Recently, albumin substituted with 28 mannose 6-phosphate moieties (M6P(28)-HSA) was found to distribute selectively to HSC in fibrotic rat livers. To assess whether this albumin can be used as a carrier for intracellular drug delivery, we explored the cellular handling of M6P(28)-HSA in HSC. Methods Reults: Application of competitive substrates for the M6P/IGFII receptor or other receptors showed that the binding of M6P-HSA to the M6P/IGFII receptor is specific. Binding was strong to activated HSC, but not to quiescent HSC. Furthermore, M6P28-HSA was extensively internalized by these cells. Using monensin, a specific inhibitor of the lysosomal pathway, proof was obtained that M6P-HSA is endocytosed via this route. The experiments performed with tissue slices, prepared from rat and human livers, revealed a specific binding and uptake of M6P(28)-HSA in both normal and cirrhotic livers. In livers from cirrhotic patients, HSC contributed predominantly to the uptake of this neoglycoprotein. Conclusions: Based on our in vivo data demonstrating the HSC-selectivity and on our in vitro data demonstrating binding and rapid internalization in activated HSC, we conclude that M6P28-HSA is applicable as a stellate cell-selective carrier for antifibrotic drugs that act intracellularly. This may have implications for the design of new strategies for the treatment of liver fibrosis.

Size of a human serum albumin molecule in solution

Abstract: The size of a human serum albumin molecule in aqueous solution containing 150 mM NaCl was studied using small-angle neutron scattering. The molecular radius of gyration was estimated to be 27.4 +/- 0.35 A. The compact sphere should have a smaller radius of gyration, whereas the popular human serum albumin model, a "cigar" 136 A long, should correspond to a greater radius of gyration. Possible shapes of the human serum albumin molecule which are in accordance with the results obtained, are the following: an extended ellipsoid less than 110 A of length or a nonsymmetrical oblate ellipsoid with a diameter of 85 A. The oblate ellipsoid might be close to the heart"-shaped structure of the crystalline human serum albumin molecule. The size of the albumin molecule does not change significantly as pH increases to 8.9. The possibility of the dynamic coexistence of various human serum albumin conformers in solution is discussed.

Pre-clinical evaluation of a methotrexate-albumin conjugate (MTX-HSA) in human tumor xenografts in vivo

Abstract: Methotrexate covalently bound to human serum albumin in a 1:1 molar ratio (MTX-HSA) is a new macromolecular drug which is currently being studied in phase I clinical trials by the German Association for Medical Oncology (AIO) Phase I/II study group. Previous studies have shown that MTX-HSA differs favorably from unbound MTX in terms of plasma half-life time, tumor accumulation of albumin and uptake mechanisms into cancer cells. To achieve optimal drug efficacy, repeated treatment cycles were necessary. To evaluate the anti-tumor activity of MTX-HSA and MTX in pre-clinical in vivo models, we selected 7 solid human tumor xenografts growing s.c. in nude mice and administered drug either i.p. or i.v. weekly for 3 weeks. The maximal tolerated dose (MTD) of MTX-HSA in nude mice was 12.5 mg/kg given i.p. on days 1, 8 and 15, whereas the MTD for free MTX was 100 mg/kg given i.v. MTX-HSA was significantly more active (p > 0.01) than MTX in 3 models. In the soft tissue sarcoma SXF 1301, MTX-HSA effected complete remission/cure after a single injection, whereas free MTX resulted in short-lasting, partial tumor regression. In the prostate-cancer model PRXF PC3M, MTX-HSA produced growth inhibition of 92.8% of control or an optimal test/control (T/C) of 7.2% compared to a T/C of 20.8% for MTX (p = 0.05). In the osteosarcoma model SXF 1410, optimal T/C values were 10.2% and 14.5%, respectively (p = 0.025). In lung cancers LXFE 409 and LXFL 529, bladder cancer BXF 1258 and breast cancer MAXF 449, both compounds were inactive. The improved therapeutic effects seen in 3 xenograft models under MTX-HSA treatment are promising and might be due to specific accumulation of the compound in solid tumors owing to their enhanced permeability and retention effect. Thus, clinical development of MTX-HSA will continue and sarcomas as well as prostate cancers will be included as potential target tumors for upcoming clinical phase II trials.

Glomerular Permselectivity Factors Are Not Responsible for the Increase in Fractional Clearance of Albumin in Rat Glomerulonephritis

Abstract: The increased fractional clearance of albumin in nephrotic states has long been attributed to glomerular permselectivity dysfunction Using radiolabeled rat serum albumin, transferrin, IgG, and polydisperse Ficoll, this study investigated the changes in their in vivo fractional clearance in puromycin aminonucleoside nephrosis and anti-glomerular basement membrane glomerulonephritis In control rats the lack of charge selectivity was confirmed by the demonstration that carboxymethyl Ficoll (valence approximately -39) had the same fractional clearance as uncharged Ficoll Both diseases exhibited similar effects on fractional clearance measurements suggesting an underlying common mechanism In disease, there was good agreement between the fractional clearance of proteins determined by radioactivity as compared to those determined by radioimmunoassay A small increase in the fractional clearance for IgG was evident in disease as compared to controls, which mirrored the change in the equivalent size Ficoll, suggesting that the increase is because of the development of a small proportion of large pores in the glomerular capillary wall There was no increase, however, in the fractional clearance of Ficoll of equivalent size to albumin in either disease, yet the fractional clearance of the albumin increased by 12 to 14 times as determined by radioactivity and 4500 to 6600 times as determined by radioimmunoassay This study demonstrates that glomerulonephritis is not a disease associated with changes in glomerular permeability to albumin but is because of alterations in albumin processing by cells distal to the glomerular basement membrane It is also apparent that approaches to glomerular pathology and proteinuria as risk factors in renal disease must be reassessed

Interaction mechanism between indoxyl sulfate, a typical uremic toxin bound to site II, and ligands bound to site I of human serum albumin.

Abstract: Purpose. The study was performed for clarifying the mechanism of interaction between indoxyl sulfate (IS), a typical uremic toxin bound to site II, and site I-ligands when bound to human serum albumin (HSA). The effect of the N to B transition on the interactions was also examined.