Showing papers on "Serum albumin published in 2000"

Potent derivatives of glucagon-like peptide-1 with pharmacokinetic properties suitable for once daily administration.

Abstract: A series of very potent derivatives of the 30-amino acid peptide hormone glucagon-like peptide-1 (GLP-1) is described The compounds were all derivatized with fatty acids in order to protract their action by facilitating binding to serum albumin GLP-1 had a potency (EC50) of 55 pM for the cloned human GLP-1 receptor Many of the compounds had similar or even higher potencies, despite quite large substituents All compounds derivatized with fatty acids equal to or longer than 12 carbon atoms were very protracted compared to GLP-1 and thus seem suitable for once daily administration to type 2 diabetic patients A structure−activity relationship was obtained GLP-1 could be derivatized with linear fatty acids up to the length of 16 carbon atoms, sometimes longer, almost anywhere in the C-terminal part without considerable loss of potency Derivatization with two fatty acid substituents led to a considerable loss of potency A structure−activity relationship on derivatization of specific amino acids generall

Biosensor analysis of the interaction between immobilized human serum albumin and drug compounds for prediction of human serum albumin binding levels.

Abstract: The interactions between a set of drugs, selected on the basis of reported human serum albumin (HSA) binding levels, and immobilized HSA were investigated using surface plasmon resonance technology. Major HSA binding sites were available after immobilization. The intensity of the signal obtained from the interaction of the drug with the HSA surface was correlated with the reported HSA binding level. Drugs were classified into groups corresponding to high, medium, or low HSA binding based on the injection of the drug at 80 microM concentration. A set of 10 drugs binding to alpha(1)-acid glycoprotein (AGP) was also investigated and correlated with reported AGP binding data. The throughput of the presented assay is 100 compounds/24 h, and the sample consumption is less than 100 microL (8 nmol).

Characterization of plasma unsaturated lysophosphatidylcholines in human and rat.

Abstract: Unsaturated lysophosphatidylcholines (lysoPtdCho) bound to albumin circulate in blood plasma and seem to be a novel transport system for carrying polyunsaturated fatty acids (PUFA) to tissues that are rich in these fatty acids, such as the brain. The potential of these lysoPtdCho as a significant source of PUFA for cells has been assessed by comparing their plasma concentration with that of unsaturated non-esterified fatty acids (NEFA) bound to albumin. In humans, the PUFA concentration was 25.9+/-3.1 nmol/ml for these lysoPtdCho, compared with 33.4+/-9.6 nmol/ml for NEFA; in rats the equivalent values are 14.2+/-0.6 and 13.1+/-1.1 nmol/ml respectively (means+/-S.E.M.). The lysoPtdCho arachidonic acid content was 2-fold (human) and 5-fold (rat) higher than that of NEFA. In human and rat plasma, unsaturated lysoPtdCho were associated mainly with albumin rather than lipoproteins. The rate and extent of the acyl group shift from the sn-2 to sn-1 position of these lysoPtdCho were studied by the incubation of 1-lyso, 2-[(14)C]C(18:2)n-6-glycerophosphocholine (GPC) with plasma. The rapid isomerization of this lipid occurred at pH 7 (20% isomerization within 2 min) and was not prevented by its association with albumin. The position of the acyl group in the lysoPtdCho circulating in plasma was studied by collecting blood directly in organic solvents containing 1-lyso,2-[(14)C]C(18:2)n-6-GPC as a marker of isomerization that occurred during sampling and analysis. Approx. 50% of the PUFA was located at the sn-2 position, demonstrating that substantial concentrations of 2-acyl-lysoPtdCho are present in plasma and are available for tissue uptake, where they can be reacylated at the sn-1 position to form membrane phospholipids.

Changes in the blood biochemical and haematological profile of neonatal calves with age

Abstract: Fourteen calves were used to investigate the changes from birth to 83 days of age in the concentrations of serum albumin, alkaline phosphatase, beta-hydroxybutyrate, plasma cortisol, serum creatine kinase, creatinine, iron, plasma fibrinogen, serum gamma-glutamyl transferase, plasma glucose, haptoglobin, serum non-esterified fatty acids, total protein, transferrin, triglycerides, urea and gamma globulin; the haematological variables measured were: basophils, eosinophils, haematocrit, haemoglobin, lymphocytes, mean cell haemoglobin, mean cell haemoglobin concentration, mean cell volume, monocytes, band neutrophils, neutrophils, platelets, red blood cells and white blood cells. The changes are presented as a series of graphs and the values are discussed in relation to the published reference ranges for adult cattle. Two populations of calves were identified which gave rise to a bimodal distribution for some of the variables. Differences in haematocrit, haemoglobin and red blood cell counts were apparent at birth, with raised values for these measurements being associated with an increased white blood cell and neutrophil count between three and 27 days of age.

The Mammalian Neuroendocrine Hormone Norepinephrine Supplies Iron for Bacterial Growth in the Presence of Transferrin or Lactoferrin

Abstract: Norepinephrine stimulates the growth of a range of bacterial species in nutritionally poor SAPI minimal salts medium containing 30% serum. Addition of size-fractionated serum components to SAPI medium indicated that transferrin was required for norepinephrine stimulation of growth of Escherichia coli. Since bacteriostasis by serum is primarily due to the iron-withholding capacity of transferrin, we considered the possibility that norepinephrine can overcome this effect by supplying transferrin-bound iron for growth. Incubation with concentrations of norepinephrine that stimulated bacterial growth in serum-SAPI medium resulted in loss of bound iron from iron-saturated transferrin, as indicated by the appearance of monoferric and apo- isoforms upon electrophoresis in denaturing gels. Norepinephrine also caused the loss of iron from lactoferrin. The pharmacologically inactive metabolite norepinephrine 3-O-sulfate, by contrast, did not result in iron loss from transferrin or lactoferrin and did not stimulate bacterial growth in serum-SAPI medium. Norepinephrine formed stable complexes with transferrin, lactoferrin, and serum albumin. Norepinephrine-transferrin and norepinephrine-lactoferrin complexes, but not norepinephrine-apotransferrin or norepinephrine-albumin complexes, stimulated bacterial growth in serum-SAPI medium in the absence of additional norepinephrine. Norepinephrine-stimulated growth in medium containing 55Fe complexed with transferrin or lactoferrin resulted in uptake of radioactivity by bacterial cells. Moreover, norepinephrine-stimulated growth in medium containing [3H]norepinephrine indicated concomitant uptake of norepinephrine. In each case, addition of excess iron did not affect growth but significantly reduced levels of radioactivity (55Fe or 3H) associated with bacterial cells. A role for catecholamine-mediated iron supply in the pathophysiology of infectious diseases is proposed.

Immunological Evidence that Non-carboxymethyllysine Advanced Glycation End-products Are Produced from Short Chain Sugars and Dicarbonyl Compounds in vivo

Abstract: The Maillard reaction that leads to the formation of advanced glycation end-products (AGE) plays an important role in the pathogenesis of angiopathy in diabetic patients and in the aging process. Recently, it was proposed that AGE were not only created by glucose, but also by dicarbonyl compounds derived from the Maillard reaction, autoxidation of sugars and other metabolic pathways of glucose. In this study, we developed four types of non-carboxymethyllysine (CML) anti-AGE antibodies that recognized proteins modified by incubation with short chain sugars and dicarbonyl compounds. AGE-modified serum albumins were prepared by incubation of rabbit serum albumin with glyceraldehyde, glycolaldehyde, methylglyoxal or glyoxal. After immunization of rabbits, four types of AGE-specific antisera were obtained that were specific for the AGE modification. To separate non-CML AGE antibodies (Ab) (non-CML AGE-Ab-2, -3, -4, and -5), these anti-AGE antisera were subjected to affinity chromatography on a matrix coupled with four kinds of AGE bovine serum albumin (BSA) or CML-BSA. These non-CML AGE antibodies were used to investigate the AGE content of serum obtained from diabetic patients on hemodialysis. Characterization of the four types of non-CML AGE antibodies obtained by immunoaffinity chromatography was performed by competitive ELISA and immunoblot analysis. Non-CML AGE-Ab-2 cross-reacted with the protein modified by glyceraldehyde or glycolaldehyde. Non-CML AGE-Ab-3 and -Ab-4 specifically cross-reacted with protein modified by glycolaldehyde and methylglyoxal, respectively. Non-CML AGE-Ab-5 cross-reacted with protein modified with glyoxal as well as methylglyoxal and glycolaldehyde. Three kinds of non-CML AGE (AGE-2, -4, and -5) were detected in diabetic serum as three peaks with apparent molecular weights of 200, 1.15, and 0.85 kD; whereas, AGE-3 was detected as two peaks with apparent molecular weights of 200 and 0.85 kD. We propose that various types of non-CML AGE are formed by the Maillard reaction, sugar autoxidation and sugar metabolism. These antibodies enable us to identify such compounds created by the Maillard reaction in vivo.

Plasma endotoxin and serum cytokine levels in patients with alcoholic hepatitis: relation to severity of liver disturbance

Abstract: Background: Endotoxin plays an important role in the initiation and aggravation of alcoholic liver disease. In this study, we evaluated plasma endotoxin levels and serum concentrations of cytokines and lipopolysaccharide binding protein (LBP) during the acute and recovery phase of patients with alcoholic hepatitis; we also explored the prognostic factors associated with a fatal outcome. Methods: Fourteen patients, consisting of eight patients with alcoholic hepatitis (AH), five cirrhotics with superimposed AH (LC+AH), and one patient with severe alcoholic hepatitis (SAH), were studied. Among these, two with LC+AH died of hepatic failure. Results: Plasma endotoxin levels in the acute phase were higher in patients with AH (184.4 ± 159.4 pg/ml) and LC+AH (206.9 ± 174.9 pg/ml) than in healthy subjects (10.4 ± 5.5 pg/ml, p < 0.001). In particular, in one patient with SAH and one of two nonsurvivors, plasma cndotoxin levels were markedly high relative to the other cases. In most survivors, plasma endotoxin levels decreased in the recovery phase, whereas they further increased at the terminal stage in one of two nonsurvivors. Serum interleukin (IL)-6 and IL-8 levels in the acute phase were significantly higher in patients with AH and LC+AH as compared with healthy subjects. These levels were especially high in nonsurvivors and in one patient with SAH. IL-10 increased in two nonsurvivors, one patient with SAH, and one with LC+AH. In the recovery phase, these cytokine levels in survivors tended to decrease, but in nonsurvivors, IL-6 remained high, and IL-8 and IL-10 further increased. Tumor necrosis factor-a levels were below the detection limit throughout the course in all patients. Serum lipopolysaccharide binding protein (LBP) generally was elevated in the acute phase and decreased in the recovery phase in all survivors, but in one of the nonsurvivors, LBP was elevated markedly at the terminal stage. In the acute phase, plasma endotoxin levels were correlated positively with white blood cell counts, neutrophil counts, and serum IL-8. IL-8 was correlated positively with neutrophil counts and negatively with serum cholinesterase, hepaplastin test, and serum albumin levels. IL-6 was correlated positively with white blood cell and neutrophil counts, C-reactive protein, and serum total bilirubin and negatively with hepaplastin test and serum total protein levels. Serum LBP was correlated positively with white blood cell and neutrophil counts. Conclusions: Endotoxemia and related elevation of IL-8 may play an important role in the activation and migration of neutrophils in patients with alcoholic hepatitis. Marked elevation of inflammatory cytokines, IL-6 and IL-8, are related to severity and poor prognosis of alcoholic hepatitis. Serum LBP may serve as an index of inflammatory reaction in alcoholics.

Elevated serum levels of soluble adhesion molecules predict death in pre‐dialysis patients: association with malnutrition, inflammation, and cardiovascular disease

Abstract: regression model showed that elevated sICAM-1 was, independent of age, SGA, CVD, and Log CRP, genesis via effects on soluble adhesion molecules or if elevated serum levels of soluble adhesion molecules are Methods. Serum levels of sVCAM-1, sICAM-1 (n= 87) and sE-selectin (n=71) were analysed in a cohort merely markers of endothelial activation in patients with chronic renal failure. of 88 patients (50±1 years) with chronic renal failure. The presence of malnutrition (subjective global assess- ment (SGA) and serum albumin), inflammation (C- Keywords: cardiovascular disease; inflammation; reactive protein (CRP), tumour necrosis factor-alpha Lp(a); malnutrition; mortality; soluble adhesion ( TNF-a), and serum hyaluronan), and cardiovascular molecules disease (CVD) were assessed at a time-point close to the start of dialysis treatment (GFR 7± 1m l/min). Blood lipid parameters were also assessed. Results. Significant correlations were observed between Log high-sensitivity CRP (hsCRP) and sVCAM-1 (R=0.39; P 1) had elevated serum has been shown to be associated with increased cardio- concentrations of sVCAM-1 (1436±94 vs 1105± vascular mortality in haemodialysis (HD) patients (2) 53 ng/ml; P<0.01) compared to well-nourished and low serum albumin concentrations are associated patients (SGA 1). Patients with clinical signs of CVD with increased mortality risk in patients on renal (n=26) had elevated serum levels of sICAM-1 replacement therapy (3). However, serum albumin is (282±18 vs 242± 9n g/ml; P<0.05) compared to 61 to a large extent influenced by factors other than patients without signs of CVD. Plasma Log lipoprotein malnutrition, and high concentrations of acute-phase (a) (Lp(a)) levels correlated significantly with sVCAM- proteins such as C-reactive protein (CRP) are correl- 1( R=0.30; P<0.01). Survival analysis by the Cox ated with low serum albumin levels in malnourished patients (4,5). Several groups have recently reported that increased

A novel macromolecular prodrug concept exploiting endogenous serum albumin as a drug carrier for cancer chemotherapy.

Abstract: Introduction. Serum proteins are potential drug carriers of antineoplastic agents due to their accumulation in tumor tissue.1 Uptake of these proteins in solid tumors is mediated by a number of factors including an increased metabolic activity of tumors, an enhanced vascular permeability of tumor blood vessels for circulating macromolecules, and a lack of a functional lymphatic drainage system in tumor tissue.2 Recently, a number of acid-sensitive albumin and transferrin conjugates with anthracyclines and the alkylating agent chlorambucil have shown promising in vitro activity.3-7 In addition, acid-sensitive doxorubicin conjugates with monoclonal antibodies and albumin doxorubicin conjugates prepared by glutaraldehyde cross-linking have shown promising antitumor efficacy in vivo.8,9 A selected acid-sensitive doxorubicin albumin conjugate that was developed in our group induced complete remissions of primary kidney tumors in murine renal carcinoma and prevented the formation of metastases in the lungs. In contrast, mice treated with doxorubicin at optimal dose manifested clearly visible kidney tumors at the end of the experiment and large numbers of lung metastases.10 This albumin doxorubicin conjugate was synthesized by coupling 1, a maleimide carboxylic hydrazone derivative of doxorubicin (see Figure 1), to thiolated albumin. 1 contains an acid-sensitive linker that allows the drug to be released at the low pH values present in lysosomes and endosomes of tumor cells. We have recently shown that 1 also binds covalently to the cysteine-34 of commercially available human serum albumin which is a mixture of mercaptalbumin and nonmercaptalbumin.11,12 Approximately 70% of circulating albumin in the blood stream is mercaptalbumin that contains an accessible cysteine-34 which is not blocked by endogenous sulfhydryl compounds such as cysteine or glutathione.12,13 Considering that free thiol groups are not found on the majority of circulating serum proteins except for albumin, cysteine-34 of endogenous albumin is a fairly unique amino acid on the surface of a circulating protein that could be exploited for developing a novel macromolecular prodrug concept. Since the maleimide group reacts specifically and selectively with thiol groups, we reasoned that it should be possible to preferentially bind maleimide drug derivatives to the HS group of the cysteine-34 position of albumin after intravenous application. In this way a macromolecular prodrug is formed after in situ coupling of a thiolbinding drug derivative to endogenous albumin in the blood circulation. Following this approach, it should be possible to avoid the ex vivo synthesis and characterization of drug albumin conjugates which are costly, are time-consuming, and rely on exogenous and possibly pathogenic albumin. The objective of the present work was to assess the feasibility and selectivity of our approach by carrying out in vitro and in vivo binding studies using the doxorubicin maleimide derivative 1. In addition, we wanted to obtain the first in vivo evidence that 1 is superior to free doxorubicin in an animal tumor model, i.e., in murine renal cell carcinoma (RENCA). In Vitro and in Vivo Binding Studies. To estimate the coupling rate and selectivity of 1 for endogenous albumin, 1 was incubated with human blood plasma at T ) 37 °C and the samples were subsequently analyzed by anion-exchange chromatography. (The ratio of drug to albumin was approximately 0.3:1; human blood plasma employed contained an albumin concentration of ∼700 μM as determined with a Vitros analyzer from Ortho-Clinical Diagnostics. 1 was synthesized previously;14 a 2000 μM solution of 1 was freshly prepared in 0.15 M NaCl, 0.004 M sodium phosphate buffer (pH 5.5), and 30 vol % of 1,2-propylene glycol for binding studies and animal experiments; doxorubicin was used as a 3400 μM stock solution in isotonic saline from Pharmacia & Upjohn.) Chromatograms after an incubation time of 5 min for 1 (Figure 2A) and for free doxorubicin (Figure 2B) under identical conditions are available as Supporting Information. Protein components were detected at 254 nm, and the anthracycline moiety was detected by simultaneous fluorescence excitation. In contrast to free doxorubicin, the major amount of 1 is associated with the albumin peak which elutes at around 23.5 min. Longer incubation periods led to a slight increase in albumin binding indicating that the coupling reaction proceeds rapidly within this short period. Incubation studies with total blood and subsequent HPLC analysis of the resulting blood plasma * To whom correspondence should be addressed: Dr. Felix Kratz, Tumor Biology Center, Department of Medical Oncology, Clinical Research, Breisacher Strasse 117, D-79106 Freiburg, FRG. Tel: 0049-761-2062176. Fax: 0049-761-2061899. E-mail: felix@ tumorbio.uni-freiburg.de. Figure 1. Structure of 1, a maleimide phenylacetylhydrazone derivative of doxorubicin. 1253 J. Med. Chem. 2000, 43, 1253-1256

Serum lipoprotein profile in patients with cancer. A comparison with non-cancer subjects.

Abstract: The association of cancer with low serum total cholesterol is well established. Less clear is the relationship of cancer with the cholesterol distribution among the different lipoprotein classes. Conflicting results have been reported on low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and serum triglyceride levels in different types of tumor. Total serum cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and serum triglycerides were analyzed in 530 patients with newly diagnosed cancer (97 with hematological malignancies, 92 with tumor of the lung, 108 of the upper digestive system, 103 of colon, 32 of breast, and 98 of the genitourinary system) and in 415 non-cancer subjects. Anthropometric (body mass index) and biochemical (serum albumin) indices of nutritional status were also determined in all subjects. Total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, serum albumin, and body mass index were significantly lower in cancer than in non cancer-subjects. The lowest values of total cholesterol, low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol were recorded in patients with hematological malignancies and the highest in patients with breast tumor. All the cancer groups, with the exception of women with breast cancer, showed significantly lower total cholesterol, low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol than age- and sex-matched non-cancer subjects. Multiple regression analysis with low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and triglycerides as dependent variables and sex, age, body mass index, albumin, and cancer (dummy variable) as independent variables, showed that cancer was independently associated with low levels of low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol and with high values of serum triglycerides. Total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, serum triglycerides, body mass index and serum albumin were significantly lower in patients with metastatic than in patients with non-metastatic solid tumor. The significant difference in low-density lipoprotein-cholesterol and serum triglycerides between patients with metastatic and non-metastatic cancer was lost when lipoprotein cholesterol and serum triglyceride levels were adjusted for nutritional variables. The lipid profile in cancer patients is characterized by low low-density lipoprotein-cholesterol, low high-density lipoprotein-cholesterol and relatively high serum triglycerides. The abnormality is a common feature of both hematological and solid tumors and is not entirely explained by poor nutrition.

Effect of pH on the thermal denaturation of whey proteins in milk.

Abstract: The effect of pH on thermal denaturation of four main whey protein fractions in skim milk was examined by gel permeation FPLC. On heating skim milk at 80 degrees C for 0.5-20.0 min over the pH range 5.2-8.8, the extent of denaturation, based on loss of solubility at pH 4.6, increased with heating time and was usually in the order immunoglobulins > serum albumin/lactoferrin > beta-lactoglobulin > alpha-lactalbumin. Rates of denaturation of the immunoglobulins and the serum albumin/lactoferrin fraction were highest at the lower end of this pH range, whereas those of beta-lactoglobulin and alpha-lactalbumin increased over most of the pH range. The effects of pH, addition of Ca, and reduction of disulfide bonds on the rates of the unfolding and aggregation stages of denaturation are discussed.

Albuminuria in patients with type 1 diabetes is directly linked to changes in the lysosome-mediated degradation of albumin during renal passage.

Abstract: Previous studies by our group have shown that albumin is metabolized in rodents during renal passage and excreted in the urine as a mixture of intact protein and albumin-derived fragments. The aim of this study was to examine whether albumin is metabolized during renal passage in nondiabetic volunteers and in type 1 diabetic patients with varying levels of albuminuria. Nine nondiabetic normoalbuminuric volunteers and 11 type 1 diabetic patients with albumin excretion rates varying from normoalbuminuria to macroalbuminuria were studied. Each subject received an intravenous injection of tritium-labeled albumin ([3H]-albumin). Urine was collected at 4 h and 24 h after injection and analyzed by size exclusion chromatography. The amount of intact and fragmented albumin was quantified, and each fraction was analyzed by radioimmunoassay (RIA) for albumin. [3H]-albumin in nondiabetic volunteers was metabolized during renal passage to small peptide fragments not detectable by conventional RIA (only 0.05-3.8% of the total urinary radioactivity was associated with intact albumin). The process responsible for albumin fragmentation was similar in diabetic patients with normoalbuminuria (intact albumin represented 0.01-4.0% of total urinary radioactivity). However, there was a reduction in the fragmentation ratio (fragmented:intact) in diabetic patients with micro- or macroalbuminuria (intact albumin represented 2.7-55.5%, P = 0.048). This change in the fragmentation ratio was directly related to the degree of albuminuria. These results have important implications for understanding the mechanisms underlying albuminuria in nondiabetic volunteers and type 1 diabetic patients. In nondiabetic volunteers, the renal processing of albumin involves a relatively rapid and comprehensive degradation of albumin to small fragments (range 1-15 kDa). The degradation process is inhibited in diabetic nephropathy in proportion to the level of albuminuria detected by RIA.

Five recombinant fragments of human serum albumin—tools for the characterization of the warfarin binding site

Abstract: Human serum albumin (HSA) interacts with a vast array of chemically diverse ligands at specific binding sites To pinpoint the essential structural elements for the formation of the warfarin binding site on human serum albumin, a defined set of five recombinant proteins comprising combinations of domains and/or subdomains of the N-terminal part were prepared and characterized by biochemical standard procedures, tryptophanyl fluorescence, and circular dichroic measurements, indicating well-preserved secondary and tertiary structures Affinity constants for binding to warfarin were estimated by fluorescence titration experiments and found to be highest for HSA-DOM I-II and HSA, followed by HSA-DOM IB-II, HSA-DOM II, and HSA-DOM I-IIA In addition, ultraviolet difference spectroscopy and induced circular dichroism experiments were carried out to get an in depth understanding of the binding mechanism of warfarin to the fragments as stand-alone proteins This systematic study indicates that the primary warfarin binding site is centered in subdomain IIA with indispensable structural contributions of subdomain IIB and domain I, while domain III is not involved in this binding site, underlining the great potential that lies in the use of combinations of recombinant fragments for the study and accurate localization of ligand binding sites on HSA

Surface composition of spray-dried particles of bovine serum albumin/trehalose/surfactant.

Abstract: Purpose. To characterize via electron spectroscopy for chemical analysis(ESCA) the surface of spray-dried particles of trehalose plus aprotein (bovine serum albumin). Additionally, to show how and whythe addition of a surfactant reduces protein adsorption, and by thismechanism could reduce protein instability during spray-drying.

Serum Albumin Level as a Predictor of Incident Coronary Heart Disease: The Atherosclerosis Risk in Communities (ARIC) Study

Abstract: Various studies have reported an inverse association between serum albumin level and incident coronary heart disease (CHD), though biologic mechanisms have not been established. The authors examined the association between serum albumin level and CHD in the Atherosclerosis Risk in Communities cohort, comprising 14,506 White and African-American middle-aged men and women. The mean albumin level in this population was 3.9 g/dl (standard deviation 0.3). During 5.2 years of follow-up, 470 incident CHD events occurred. The hazard ratio for incident CHD associated with a 1-standard deviation decrease in serum albumin level was 1.26 (95% confidence interval (CI): 1.15, 1.38) after adjustment for age, gender, and ethnicity and 1.18 (95% CI: 1.07, 1.30) after additional adjustment for covariates related to CHD. Hazard ratios were similar across gender and ethnic groups. However, there was statistically significant effect modification by smoking status, with hazard ratios of 1.01 (95% CI: 0.84, 1.22) among never smokers, 1.09 (95% CI: 0.92, 1.30) among former smokers, and 1.35 (95% CI: 1.17, 1.54) among current smokers. Further adjustment for factors related to renal disease, nutrition, platelet aggregation, inflammation, use of angiotensin-converting enzyme inhibitors, and hemostasis factors attenuated the albumin-CHD relation only slightly. In this study, serum albumin was inversely associated with incident CHD at the baseline examination in current smokers but not in never or former smokers. Albumin level may be a marker of susceptibility to the inflammatory response that results from smoking.

Prevention of albuminuria by aminoguanidine or ramipril in streptozotocin-induced diabetic rats is associated with the normalization of glomerular protein kinase C.

Abstract: This study examined whether the prevention of diabetes-related albuminuria by aminoguanidine (AG) or ramipril (RAM) may be mediated by a common post-glomerular basement membrane renal intracellular mechanism involving protein kinase C (PKC). The renal handling of albumin was examined over 24 weeks in control and streptozotocin (STZ)-induced diabetic rats. A radioimmunoassay (RIA) that measures intact albumin, and intravenously injected tritium-labeled rat serum albumin, was used to assess the proportion of intact albumin and albumin fragments in urine. Diabetes was induced in male Sprague-Dawley rats by the intravenous administration of STZ at a dose of 50 mg/kg. Age-matched control rats received buffer alone. Diabetes was characterized by an increase in blood glucose (>15 mmol/l), an increase in GHb (means at 24 weeks 29.3+/-1.1%; control 6.1+/-0.1%, P<0.005), an increase in glomerular filtration rate (GFR) (4.13+/-0.15 ml/min; control 3.54+/-0.19 ml/min, P<0.005), an increase in intact albumin excretion rate (expressed as geometric mean 11.64 times/divided by 2.11 mg/24 h; control 0.74 times/divided by 1.57 mg/24 h, P<0.005) as measured by RIA, and an increase in glomerular PKC activity (26.83+/-2.38 pmol x mg(-1) x min(-1); control 14.6+/-2.99 pmol x mg(-1) x min(-1), P<0.005). Treatment of diabetic rats with either AG or RAM prevented the rise in intact albuminuria and glomerular PKC activity. Renal lysosomal cathepsin activity decreased in diabetic rats and this was not prevented by AG or RAM. Neither drug affected glycemic control or GFR, but RAM reduced systolic blood pressure (BP), whereas AG did not. These data indicate that urinary excretion of intact albumin and albumin-derived fragments in diabetes may be modulated independently of glycemic control (AG and RAM) and systolic BP (RAM). While both drugs are known for their different mechanisms of action, the fact that both prevent diabetes-related increases in glomerular PKC activity and albuminuria supports the hypothesis that PKC plays a central role in the development of diabetic nephropathy.

Therapeutic effect of melatonin on carbon tetrachloride-induced acute liver injury in rats.

Abstract: The therapeutic effect of melatonin on acute liver injury was examined in rats intoxicated with carbon tetrachloride (CCl4). Melatonin (10, 50, or 100 mg/kg body weight [BW]) was intraperitoneally administered to male Wistar rats 6 hr after intraperitoneal injection of CCl4 (1.6 g/kg BW) at which time an apparent liver injury occurred. This post-melatonin administration dose dependently prevented the progression of liver injury at 24 hr after CCl4 injection, judging from the levels of serum transaminases, indices of liver cell damage. Rats injected with CCl4 alone showed an increase in liver lipid peroxide (LPO) content and a decrease in liver reduced glutathione content at 6 and 24 hr after the injection. The post-melatonin administration dose dependently ameliorated both changes found at 24 hr after CCl4 injection. Rats injected with CCl4 alone showed an increase in liver triglyceride (TG) content and decreases in serum TG concentration and liver tryptophan 2,3-dioxygenase (TDO) activity, a marker of the inhibition of liver protein synthesis by CCl4, at 6 and 24 hr after the injection, and also a decrease in serum albumin concentration at 24 hr. The changes in serum TG, albumin concentration, liver TG content, and TDO activity found at 24 hr after CCl4 injection were not ameliorated by the post-administration of melatonin. The same administration of melatonin dose dependently reduced liver LPO content in CCl4-untreated rats. These results indicate that melatonin exerts a therapeutic effect on CCl4-induced acute liver injury in rats, possibly through its antioxidant action.