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Hepatitis B infection and aflatoxin biomarker levels in Gambian children.

OBJECTIVES: To examine the relationship between hepatitis B virus (HBV) infection and biomarkers of aflatoxin exposure in West African children. METHODS: Sera from 444 children aged 3-4 years who were selected to be representative of their communities were analysed for aflatoxin-albumin (AF-alb) adducts and markers of hepatitis B infection. RESULTS: There was large interindividual variation in adduct levels (range: 2.2 to 459 pg AF-lysine eq./mg albumin). Adduct level was strongly correlated with season, with an approximately twofold higher mean level in the dry season than the wet. Geometric mean adduct levels in uninfected children, chronic carriers and acutely infected children were 31.6 (n = 404), 44.9 (n = 34) and 96.9 (n = 6) pg/mg, respectively. The relationship of AF-alb level to ethnicity, month of sampling and HBV status was examined in a multiple regression model. Month of obtaining the blood sample (P = 0.0001) and HBV status (P = 0.0023) each made a highly significant contribution to the model; the high AF-alb levels were particularly associated with acute infection. Elevated serum transaminase levels were significantly (P < 0.002) associated with HBV status, with acutely infected children having the highest levels. Ethnicity was not significantly associated with AF-alb adduct levels in the model (P = 0.09). CONCLUSIONS: HBV infection and month of sampling both significantly influence AF-alb adduct levels. The effect of seasonality on adducts was also observed in a previous study of 347 Gambian adults, although there was no correlation between adduct level and HBV status in that population. This difference between children and adults may reflect a more severe effect of HBV infection, particularly acute infection, in childhood on hepatic AF metabolism.

Aflatoxins↗

Cigarette smoking and increased urine albumin excretion are interrelated predictors of nephropathy progression in type 2 diabetes.

BACKGROUND: Increased urine albumin excretion (UAE) predicts nephropathy progression in type 2 diabetes, whereas improved blood pressure (BP) control and angiotensin-converting enzyme (ACE) inhibition ameliorate both albuminuria and nephropathy progression. Cigarette smoking (CS) predicts nephropathy progression in patients with type 2 diabetes despite improved BP control and ACE inhibition. We tested the hypothesis that CS and increased UAE are interrelated predictors of nephropathy progression in patients with type 2 diabetes undergoing improved BP control and ACE inhibition. METHODS: We prospectively followed plasma creatinine (P(cr)) levels and UAE as albumin-creatinine (alb-cr) ratio for 63.9 +/- 0.6 months in 84 patients with type 2 diabetes undergoing BP control with regimens including ACE inhibitors. RESULTS: Despite ACE inhibition and mean BP reduction from 113.7 +/- 1.8 to 92.3 +/- 0.6 mm Hg (P < 0.001), P(cr) increased (1.03 +/- 0.02 to 1.25 +/- 0.04 mg/dL [91.1 +/- 1.8 to 110.5 +/- 3.5 micromol/L]; P < 0.001) during follow-up. Regression analysis showed that entry alb-cr ratio, but not CS, predicted nephropathy progression when considering both factors together, but CS predicted progression only when excluding alb-cr ratio. Nephropathy progression was minimal for lower levels of alb-cr ratio at entry, but increased progressively for levels greater than 300. Alb-cr ratio increment during follow-up directly correlated with nephropathy progression (r2 = 0.307; P < 0.001) and was greater in smokers than nonsmokers (1,878 +/- 346 versus 553 +/- 214; P < 0.001). CONCLUSION: Data show that CS and increased UAE are interrelated predictors of nephropathy progression in patients with type 2 diabetes, and CS increases UAE in these patients despite improved BP control and ACE inhibition.

Adult↗

Embryoid-body cells derived from a mouse embryonic stem cell line show differentiation into functional hepatocytes.

Embryonic stem (ES) cells have a potential to differentiate into various progenitor cells. Here we investigated the differentiation capacity of mouse ES cells into hepatocytes both in vitro and in vivo. During the culture of embryoid bodies (EBs) derived from ES cells, albumin (ALB) messenger RNA (mRNA) was expressed within 12 days after removal of leukemia inhibitory factor, and alpha-fetoprotein (AFP) mRNA was observed within 9 days without additional exogenous growth factors. In ES cells and early EBs, by contrast, neither ALB mRNA nor AFP mRNA was observed. ALB protein was first detected at day 15 and the level increased with the culture period. The differentiation of EBs facilitated the synthesis of urea with the culture period, whereas early EBs and ES cells produced no urea. These results suggest that cultured EBs contain hepatocytes capable of producing ALB and urea. ES cells and the isolated cells from EBs were transplanted through portal vein to the liver after 30% partial hepatectomy of female mice pretreated with 2-acetylaminofluorene. Four weeks after transplantation with isolated cells from day-9 EBs, ES-derived cells containing Y-chromosome in the liver were positive for ALB (0.2% of total liver cells), whereas teratoma was found in mice transplanted with ES cells or EBs up to day 6. The incidence of teratoma was decreased with the culture duration and no teratoma was observed in the liver transplanted with isolated cells from day-9 EBs. In conclusion, our in vitro and in vivo experiments revealed that cultured EBs contain functional hepatocytes or hepatocyte-like cells.

2-Acetylaminofluorene↗

Evidence for hepatocellular differentiation in alpha-fetoprotein-negative gastric adenocarcinoma with hepatoid morphology: a study with in situ hybridisation for albumin mRNA.

AIM: Hepatoid adenocarcinoma, a putative chemosensitive tumour, is defined as a tumour with aberrant hepatocellular differentiation occurring in extrahepatic organs such as the stomach, usually in the gastrointestinal tract. Differentiation in the hepatocellular direction is usually supported by the production of alpha-fetoprotein (AFP) and, more recently, albumin (ALB) mRNA. We investigated ALB mRNA to address whether adenocarcinoma with hepatoid morphology, regardless of AFP production, can be diagnosed solely by morphological criteria as a hepatoid adenocarcinoma. METHODS: We performed in situ hybridisation (ISH) and immunohistochemistry (IH) for ALB mRNA on AFP-negative gastric adenocarcinomas with hepatoid morphology. AFP-positive hepatoid adenocarcinomas and AFP-negative conventional gastric adenocarcinomas were also investigated as positive and negative controls, respectively. RESULTS: All three gastric adenocarcinomas with hepatoid morphology with no evidence of AFP production stained positive for ALB mRNA, thus providing evidence of differentiation in the hepatocellular direction. Three of five cases of AFP-positive hepatoid adenocarcinoma of the stomach were positive for ALB mRNA, while 11 cases of AFP-negative conventional gastric adenocarcinoma were negative. CONCLUSION: The present study demonstrates that, irrespective of AFP production, gastric adenocarcinoma with morphological patterns suggestive of hepatoid differentiation should be diagnosed as hepatoid adenocarcinoma with important prognostic implications.

Adenocarcinoma↗

Specific binding sites for albumin restricted to plasmalemmal vesicles of continuous capillary endothelium: receptor-mediated transcytosis.

The interaction of homologous and heterologous albumin-gold complex (Alb-Au) with capillary endothelium was investigated in the mouse lung, heart, and diaphragm. Perfusion of the tracer in situ for from 3 to 35 min was followed by washing with phosphate-buffered saline, fixation by perfusion, and processing for electron microscopy. From the earliest time examined, one and sometimes two rows of densely packed particles bound to some restricted plasma membrane microdomains that appeared as uncoated pits, and to plasmalemmal vesicles open on the luminal front. Morphometric analysis, using various albumin-gold concentrations, showed that the binding is saturable at a very low concentration of the ligand and short exposure. After 5 min, tracer-carrying vesicles appeared on the abluminal front, discharging their content into the subendothelial space. As a function of tracer concentration 1-10% of plasmalemmal vesicles contained Alb-Au particles in fluid phase; from 5 min on, multivesicular bodies were labeled by the tracer. Plasma membrane, coated pits, and coated vesicles were not significantly marked at any time interval. Heparin or high ionic strength did not displace the bound Alb-Au from vesicle membrane. No binding was obtained when Alb-Au was competed in situ with albumin or was injected in vivo. Gold complexes with fibrinogen, fibronectin, glucose oxidase, or polyethyleneglycol did not give a labeling comparable to that of albumin. These results suggest that on the capillary endothelia examined, the Alb-Au is adsorbed on specific binding sites restricted to uncoated pits and plasmalemmal vesicles. The tracer is transported in transcytotic vesicles across endothelium by receptor-mediated transcytosis, and to a lesser extent is taken up by pinocytotic vesicles. The existence of albumin receptors on these continuous capillary endothelia may provide a specific mechanism for the transport of albumin and other molecules carried by this protein.

Animals↗

Effect of progressive haemodilution with hydroxyethyl starch, gelatin and albumin on blood coagulation.

We have compared the effects of progressive (30% and 60%) in vitro haemodilution with hydroxyethyl starch (HES), gelatin (GEL) and albumin (ALB) with haemodilution using 0.9% saline in 96 patients by thrombelastography. Haemodilution with HES, GEL and ALB significantly (P < 0.05) compromised coagulation time (k), angle alpha and maximal amplitude (MA), with HES having the most negative effect at 30% and 60% haemodilution (P < 0.05). Haemodilution with saline significantly affected all variables of blood coagulation and clot lysis measured by thrombelastography, resulting in an increased coagulability at 30% haemodilution. To specifically assess the intrinsic effect of plasma expander molecules on blood coagulation and clot lysis, we analysed the difference between saline diluted blood (same degree of haemodilution) and plasma expander diluted blood. Prolongation of reaction time (r) was found for HES at 30% and 60% haemodilution and for ALB at 60% haemodilution and an increase in clot lysis by HES, GEL and ALB became evident. We conclude that HES, GEL and ALB compromised blood coagulation, while the maximum effect was found with HES.

Adolescent↗

Analbuminemia does not significantly influence hepatocarcinogenesis on comparing F344 rats and a congenic line carrying the analbuminemic mutation.

Analbuminemic rats differ from Sprague-Dawley rats (SD), their strain of origin, with respect to carcinogenic susceptibility of various organs. We compared hepatic changes after carcinogenic treatments in two kinds of analbuminemic rats with different genetic backgrounds (NAR isolated from outbred SD and F344-alb F344-congenic analbuminemic rats) as well as in their parent strains. After the rats were treated according to the Solt-Farber protocol [a single dose of diethylnitrosamine (DEN) followed by dietary 2-acetylaminofluorene (2-AAF) plus partial hepatectomy], F344 and F344-alb demonstrated similar numbers of much larger hyperplastic hepatic nodules (HPN) than SD or NAR, while in the latter two cases, sizes are approximately the same, NAR had a greater number of HPN. When HPN cells of F344 rats were infused into the portal vein of F344 and F344-alb, followed by treatment with the Solt-Farber protocol, the transplanted cells formed almost the same numbers of colonies of almost equal size within the livers in these two strains of rats. With continuous administration of a 2-acetylaminofluorene (2-AAF) diet, which can change the normally albumin-negative hepatocytes of analbuminemic rats to albumin-positive cells, this process occurred earlier in F344-alb than NAR, but almost the same numbers were reached after 30 days. The results demonstrate responses to significantly differ between NAR and F344-alb, with both resembling their parent strains to a large extent, indicating that genetic background has the major influence on susceptibility to hepatic carcinogenesis, rather than analbuminemia itself.

2-Acetylaminofluorene↗

The effect of proteinase inhibitors on glomerular albumin permeability induced in vitro by serum from patients with idiopathic focal segmental glomerulosclerosis.

BACKGROUND: The putative circulating factor responsible for the glomerular permeability alterations induced in vitro by serum from patients affected by focal segmental glomerulosclerosis (FSGS) remains unidentified. We have observed that a serine proteinase isolated from patient serum increases albumin permeability in isolated glomeruli. The objective of the present study was to determine the effect of various proteinase inhibitors on glomerular albumin permeability (P(alb)) in isolated glomeruli incubated with FSGS serum. METHODS: The study population consisted of 12 FSGS patients (eight males; mean age: 21+/-10 years) previously shown to have elevated serum albumin permeability activity. P(alb) was determined by measuring the change in glomerular volume induced by applying oncotic gradients to isolated healthy rat glomeruli treated with patient serum in comparison to control serum. Solutions of seven different proteinase inhibitors (0.5 mg/ml) were added to the incubation media with the sera (1:1 vol/vol): serine proteinase inhibitors (PMSF, leupeptin, aprotinin, gabexate mesylate), the cysteine proteinase inhibitor E-64, the metalloproteinase inhibitor EDTA and the aspartate proteinase inhibitor pepstatin. Sera from the same patients were also tested with the addition to the incubation media of quinaprilat, an inhibitor of the metalloproteinase angiotensin-converting enzyme. RESULTS: Mean P(alb) of the sera was 0.86+/-0.11, with the addition of PMSF 0.41+/-0.09, leupeptin 0.30+/-0.17, aprotinin 0.09+/-0.14, gabexate mesylate 0.27+/-0.25, E-64 0.81+/-0.09, EDTA 0.68+/-0.10 or pepstatin 0.76+/-0.11. The mean P(alb) of the sera combined with quinaprilat was reduced to 0.34+/-0.35. Thus, only the serine proteinase inhibitors consistently blocked the increased P(alb) induced by the FSGS sera. CONCLUSIONS: In the cascade of events that lead to the initiation of glomerular fibrosis in FSGS, the putative glomerular permeability factor associated with FSGS may require a serine proteinase to effect its activity.

Adult↗

Large-dose administration of 6% hydroxyethyl starch 200/0.5 total hip arthroplasty: plasma homeostasis, hemostasis, and renal function compared to use of 5% human albumin.

Within a daily dose of 20 mL/kg, medium-molecular hydroxyethyl starch (HES) is a safe and effective colloid for intravascular blood volume replacement. The effect of large doses on coagulation and renal function is unknown. We prospectively studied 41 patients undergoing total hip arthroplasty during the perioperative period. Inevitable blood loss was replaced with HES (HES group) or albumin (ALB group) in combination with packed red blood cells (PRBC), fresh frozen plasma (FFP), and platelets. Hemodynamic, oncotic, coagulation, and renal functions were compared initially, at the end of surgery, during the postoperative period (1, 3, and 6 h), and also with respect to the volume of colloid solution administered (1500, 2000, and 3000 mL). Total intake and output balances, as well as the costs of blood replacement therapy, were registered at the end of the study. We found differences in oncotic variables even at 6 h after surgery (total serum proteins [TSP]:HES 36.4 +/- 7.9 g/L versus ALB 55.6 +/- 6.1 g/L, P < 0.01; serum albumin:HES 25.5 +/- 5.3 g/L versus ALB 42.0 +/- 5.6 g/L, P < 0.01). Colloid osmotic pressure (COP) and hemodynamic, coagulation, and renal functions were comparable, as was total blood loss (HES 4247 +/- 2090 mL versus ALB 4051 +/- 2830 mL). Total requirements for colloid solutions (HES 35.9 +/- 7.4 mL/kg versus ALB 33.9 +/- 10.5 mL/kg), PRBC, FFP, or platelets were comparable, whereas total cost of blood replacement therapy was 33% less in the HES group. With respect to efficacy and side effects on coagulation and renal function, medium molecular HES is an appropriate and economic alternative to albumin at daily doses of up to at least 36 mL/kg.

Aged↗

Immobilized albumin-immunoglobulin G for improved hemocompatibility of biopolymers.

Efforts to render blood contacting surfaces less thrombogenic have included chemical modification of the polymer, as well as surface modifications with proteins, anticoagulants, or antiplatelet agents. Studies reported from this laboratory in the past have shown that certain surfaces pretreated with albumin-Immunoglobulin G (alb-IgG) become relatively more hemocompatible (reduced platelet adhesion, minimal thrombus). However, absorbed proteins, including alb-IgG, desorb rapidly when exposed to circulating blood. Therefore, efforts were made to immobilize alb-IgG on glass or Biomer as follows: a 2 mg/ml solution of IgG was crosslinked with glutaraldehyde on the test surface. Crosslinked IgG was then treated with mercaptoethanol to reduce the disulfide bonds, followed by incubation with albumin previously reduced with mercaptoethanol under conditions that allowed reassociation of disulfide bridges between albumin and crosslinked IgG. Alb-IgG immobilized at the test surface following this method was found to remain at the interface when the surface was exposed to blood in vitro for up to 7 days under static conditions. Glass or Biomer surfaces with crosslinked Alb-IgG showed considerable reduction in the adhesion of 111In-platelets and adsorption of 125I-fibrinogen when test surfaces were analyzed in a flow chamber. Under identical experimental conditions, surfaces with crosslinked albumin alone were not effective in reducing the adhesion of platelets. Crosslinked IgG or immobilization of IgG on crosslinked albumin following the above methods rendered the surfaces more thrombogenic. It was noted, however, that crosslinked proteins on Biomer were dislodged rapidly in areas with turbulent flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Differential inhibition of platelet aggregation and calcium mobilization by nitroglycerin and stabilized nitric oxide.

We compared the mechanisms of the antiplatelet effects of nitroglycerin (NTG) and stabilized nitric oxide (NO). Stabilized NO was in the form of S-nitrosothiols [S-nitroso-albumin (S-NO-Alb) and S-nitrosocaptopril (S-NO-Cap)] or heme-NO [sodium nitro-prusside (SNP)]. The molecular structure of S-NO-Cap was confirmed by mass spectrometry. NTG, SNP, S-NO-Alb, and S-NO-Cap inhibited ADP-induced platelet aggregation dose dependently. The inhibitory IC50 value was 109 microM for NTG, 0.98 microM for SNP, 2.99 microM for S-NO-Alb, and 2.5 microM for S-NO-Cap. NTG (200 microM) released 15.4 microM nitrite anion into platelet-rich plasma (PRP) after 60-min incubation, to which platelets contributed 5.4 microM. On the other hand, SNP and S-NO-Cap released undetectable amounts of NO2- when incubated in either PRP or platelet-poor plasma (PPP). The platelet cytosolic calcium ion (Ca2+) concentration was measured fluorometrically in Fura-2-loaded gel-filtered platelets. Thrombin-induced Ca2+ mobilization was significantly inhibited by 10 microM NTG, SNP, S-NO-Alb, and S-NO-Cap, whereas resting Ca2+ was unaltered. Ca2+ mobilization was inhibited 28.6% by NTG, 91.9% by SNP, 90.0% by S-NO-Alb, and 92.7% by S-NO-Cap. These results demonstrate that NTG is an exogenous donor of NO, but releases it only slowly. On the other hand, SNP and S-nitrosothiols inhibited platelet aggregation by the action of stabilized NO incorporated in their structure and did not release NO. NTG and stabilized NO shared a common mechanism of antiplatelet activity, which involved inhibition of calcium mobilization.

Adult↗

Increased levels of aflatoxin-albumin adducts are associated with CYP3A5 polymorphisms in The Gambia, West Africa.

OBJECTIVES: Major risk factors for hepatocellular carcinoma (HCC) are hepatitis viruses and exposure to aflatoxins, including aflatoxin B1 (AFB1). The mutagenic effect of AFB1 results from hepatic bioactivation to AFB1-exo-8,9-epoxide. This is in part catalysed by CYP3A5, an enzyme expressed polymorphically. We investigated the role of CYP3A5 polymorphisms in the formation of AFB1-exo-8,9-epoxide in The Gambia, a population exposed to high aflatoxin levels. METHODS: Common CYP3A5 polymorphisms were identified in an African-American population. Subsequently, 288 Gambian subjects were genotyped and CYP3A5 activity predicted using haplotypes of the three variant loci (CYP3A5*3, *6 and *7) associated with decreases in protein expression. CYP3A5 expression was then compared to aflatoxin-albumin (AF-alb) adduct, a biomarker of AFB1 bioactivation; data were also analysed in relation to expression of other aflatoxin-metabolizing enzymes. RESULTS: CYP3A5 haplotypes reflecting high CYP3A5 protein expression were associated with increased AF-alb. Compared to individuals with predicted low expression those predicted to express CYP3A5 from one allele displayed 16.1% higher AF-alb (95% CI: -2.5, 38.2, P = 0.093) and homozygous expressers displayed 23.2% higher AF-alb levels (95% CI: -0.01, 52.0, P = 0.051). The effect of the CYP3A5 polymorphism was strongest in individuals with low CYP3A4 activity with a 70.1% increase in AF-alb (95% CI: 11.8, 158.7, P < 0.05) in high compared to low expressers. A similar effect was observed for individuals with null alleles of GSTM1, which conjugates the AFB1-exo-8,9-epoxide to reduced glutathione. CONCLUSIONS: The CYP3A5 polymorphism is associated with increased levels of the mutagenic AFB1-exo-8,9-epoxide, particularly in individuals with low CYP3A4, and this may modulate individual risk of HCC.

Adolescent↗

Secretion of immunoglobulins and plasma proteins from the colonic mucosa: an in vivo study in man.

There are no available data on immunoglobulins and albumin outputs into the normal human colon. We thus measured the intracolonic secretion rates of IgA, IgG, IgM, secretory component (SC) and plasma proteins (albumin (Alb), orosomucoid (Oro), transferrin (Transf) and alpha 2-macroglobulin (alpha 2-M)). Using a pancolonic perfusion technique in 10 healthy volunteers (six females, four males, mean age 24 years), concentrations and outputs of Alb, immunoglobulins, SC, Oro, Transf and alpha 2-M were measured in the rectal effluents by immunoradiometric assay. Monomeric (m) and polymeric (p) IgA distribution was analysed by sucrose density ultracentrifugation. The secretion of polymeric IgA (p-IgA) was 153 micrograms/min, i.e. 220 mg/day, exceeding that of other immunoglobulins (m-IgA 8.5 micrograms/min; IgG 33.5 micrograms/min; IgM 17 micrograms/min) and of non-immunoglobulin proteins (Alb 104 micrograms/min; Oro 9 micrograms/min; Transf 7 micrograms/min; alpha 2-M 4.5 micrograms/min). p-IgA was entirely linked to SC (secretory IgA) and 12% of SC was in free form. About 62% of total IgA was IgA2. For each protein, a relative coefficient of excretion (RCE) was calculated (colon to serum concentration ratio expressed relative to that of Alb). The p-IgA, IgM and m-IgA RCE were 277, 6 and 2.2 times higher than the values predicted from their molecular weight. RCE of non-immunoglobulin proteins also exceeded the values expected from a passive seepage from the vascular compartment. The intracolonic clearance of Alb extrapolated to 24 h was only 3.7 ml/day. These results show the high local production and/or the facilitated transport to the colonic lumen of p-IgA, and are in very good agreement with the distribution of plasma cells in the colonic mucosa.

Adult↗

Components of normal serum block the focal segmental glomerulosclerosis factor activity in vitro.

BACKGROUND: Sera from some patients with focal segmental glomerulosclerosis (FSGS) increase glomerular albumin permeability (P(alb)) in vitro. The hypothesis that a component of normal serum can protect the glomerular permeability barrier was tested using sera from FSGS patients, normal individuals, and several mammalian and avian species. METHODS: In most experiments, isolated rat glomeruli were incubated in medium containing FSGS serum known to increase P(alb) in vitro, normal serum, or both active FSGS and normal serum. In other experiments, fractions of normal serum and serum from other vertebrate species were incubated with active FSGS serum. P(alb) was calculated from glomerular capillary expansion in response to an oncotic gradient. To enrich the blocking activity, normal pooled human plasma was subjected to various biochemical manipulations. RESULTS: Normal human serum prevented the increase in P(alb) (active FSGS sera, 0.77 +/- 0.12; active FSGS sera:normal serum, 1:1 mix, 0.06 +/- 0.30, P < 0.001). Protection diminished as the concentration of normal serum was decreased. Specific fractions of human serum, including human albumin and immunoglobulin fractions, were not protective. Blocking activity was present in 80% ammonium sulfate precipitate and certain fractions from size-exclusion chromatography of normal pooled human plasma. Normal serum from each of the vertebrate species tested also prevented the increase in P(alb). Preincubation with normal serum was protective during subsequent incubation with FSGS serum, but normal serum was not protective after preincubation with FSGS serum. CONCLUSIONS: We conclude that a factor or factors in normal serum block the permeability effect of active FSGS sera. This phenomenon may account for variability in proteinuria among patients with FSGS and may explain inconsistent proteinuria following injection of FSGS sera into experimental animals. Characterization of the protective substance(s) and the mechanism by which the increase in permeability is blocked may provide insight into the pathogenesis of FSGS.

Animals↗

Nitric oxide preserves the glomerular protein permeability barrier by antagonizing superoxide.

BACKGROUND: The interaction of nitric oxide with superoxide (O2-) is a major O2- scavenging mechanism that can minimize O2 (-)-mediated oxidative stress. Glomeruli produce both nitric oxide and O2- and generation of both radicals is increased in various forms of glomerular disease. O2- increases glomerular capillary permeability to albumin (P(alb)). The present studies tested the hypothesis that nitric oxide opposes this effect, thereby preserving the glomerular protein permeability barrier. METHODS: P(alb) was determined in isolated rat glomeruli by measuring the change in glomerular volume in response to an experimental oncotic gradient. Changes in P(alb) in response to O2- generated by tumor necrosis factor-alpha (TNF-alpha) or xanthine/xanthine oxidase (X/XO) was assessed under conditions of nitric oxide depletion and repletion. RESULTS: Incubation of rat glomeruli with the nitric oxide synthase (NOS) inhibitor L-N(G)-monomethyl arginine (L-NMMA) increased P(alb.) This effect was reversed by the nitric oxide donor diethylenetriamine NONOate (DETA-NONOate) and by the superoxide dismutase (SOD) mimetic Tempol. O2- generated after incubation with TNF-alpha or X/XO increased P(alb). This effect was blocked by DETA-NONOate. CONCLUSION: We demonstrate that nitric oxide protects the glomerular filtration barrier from injury caused by O2- and suggest that inhibition of nitric oxide synthesis could enhance O2(-)-mediated oxidative injury under pathologic conditions.

Albumins↗

Terbutaline vs albuterol for out-of-hospital respiratory distress: randomized, double-blind trial.

OBJECTIVE: To determine the efficacy and safety of single doses of subcutaneous terbutaline (TERB) or nebulized albuterol (ALB) during out-of-hospital treatment for respiratory distress from asthma or chronic obstructive pulmonary disease. METHODS: Patients aged > 18 years who had respiratory distress were enrolled in a double-placebo, double-blind, randomized trial. Paramedics measured respiratory severity using an empiric score [respiratory rate, wheezing, speech, and peak expiratory flow rate (PEFR)], and the patients rated their own respiratory distress using a visual analog scale (VAS). The patients received O2 plus ALB (2.5 mg) and saline injection (n = 40) or TERB (0.25 mg) and saline aerosol (n = 43). RESULTS: The groups were similar with respect to age, gender, initial empiric scores (median score 9 for both groups), PEFRs (89 +/- 84 L/min, mean +/- SD, for ALB vs 97 +/- 84 L/min for TERB), and respiratory distress VAS scores. Both groups showed significant improvement in their respiratory distress VAS scores by the time of ED arrival. The ALB group had a greater improvement in respiratory distress VAS score than did the TERB group (p < 0.05). Empiric scores, PEFR scores, and hospital admission frequencies were not significantly different. No complication was observed. CONCLUSION: The out-of-hospital administration of either aerosolized ALB or subcutaneous TERB reduced respiratory severity. Albuterol provided greater subjective improvement in respiratory distress.

Administration, Inhalation↗

Use of the Vettest 8008 and refractometry for determination of total protein, albumin, and globulin concentrations in feline effusions.

BACKGROUND: Pleural and peritoneal effusion is a common clinical finding in feline practice. Determination of fluid albumin (ALB) and globulin (GLOB) concentrations in addition to total protein (TP) concentration can be helpful in diagnosing or ruling out certain diseases in cats, especially feline infectious peritonitis (FIP). OBJECTIVE: The objective of this study was to compare effusion TP, ALB, and GLOB results obtained by a refractometer and a bench-top dry chemistry analyzer with those results obtained by a reference method. METHODS: Twenty-six pleural and 14 peritoneal effusion samples were analyzed from 40 cats with various diseases. TP and ALB concentrations were determined by a reference automated wet chemistry analyzer (Kone Specific, Kone Instruments, Espoo, Finland), a bench-top dry chemistry analyzer (Vettest 8008, IDEXX Laboratories Ltd, Chalfont St Peter, UK), and a refractometer (Atago SPR-T2, Atago Co, Tokyo, Japan). GLOB, albumin to globulin (A/G) ratio, and globulins as a percentage of total proteins (GLOB%) were calculated. Results were analyzed by paired t tests, difference plots, and Deming s regression analysis. RESULTS: Correlation coefficients (r) for TP with Vettest versus Kone and refractometer versus Kone methods were.97 and.94, respectively. GLOB and GLOB% values were significantly higher and A/G ratios were significantly lower with Vettest versus Kone methods. Correlation coefficients for ALB, GLOB, GLOB% and A/G ratio with Vettest versus Kone methods were.86,.93,.82, and.73, respectively. Although correlation with other methods was good, the refractometer underestimated TP concentrations in 3 samples. CONCLUSIONS: The refractometer is an acceptable method for determination of TP concentration in feline effusions. The Vettest 8008 also is an acceptable method for the determination of TP and ALB concentrations, however, calculated A/G ratios obtained with the Vettest are unacceptable.

Albumins↗

Absorption of intact albumin across rat alveolar epithelial cell monolayers.

Transport characteristics of intact albumin were investigated using primary cultured rat alveolar epithelial cell monolayers. The apical-to-basolateral (ab) flux of intact fluorescein isothiocyanate (FITC)-labeled albumin (F-Alb) is greater than basolateral-to-apical (ba) flux at the same upstream [F-Alb]. Net absorption of intact F-Alb occurs with half-maximal concentration of approximately 1.6 microM and maximal transport rate of approximately 0.15 fmol.cm(-2).s(-1). At 15 and 4 degrees C, both ab and ba F-Alb fluxes are not different from zero, collapsing net absorption. The presence of excess unlabeled albumin (but not other macromolecule species) in either the apical or basolateral fluid significantly reduces both ab and ba unidirectional F-Alb fluxes. Photoaffinity labeling of apical cell membranes revealed an approximately 60-kDa protein that exhibits specificity for albumin. These data indicate that net absorption of intact albumin takes place via saturable receptor-mediated transcellular endocytotic processes recognizing albumin, but not other macromolecules, that may play an important role in alveolar homeostasis in the mammalian lung.

Animals↗