Enzyme-linked immunoabsorbent assay detection of a soluble form of urokinase plasminogen activator receptor in vivo

The receptor for urokinase plasminogen activator (uPA-R, CD87) is a glycosylphosphatidylinositol (GPI)-anchored 50 to 65 kD glycoprotein that, by regulating membrane-associated plasmin activity, may facilitate the invasion of inflammatory and malignant cells. Certain other GPI-anchored glycoproteins are shed from the cell membrane and exist as soluble products in vitro and in vivo. To determine if uPA-R undergoes a similar phenomenon, we have developed a sensitive enzyme- linked immunoabsorbent assay (ELISA) (using a rabbit antiserum as both capture and detection reagents) to measure the quantity of soluble uPA- R (suPA-R) in tissue culture supernatants and biologic fluids. Using this ELISA, we have detected suPA-R in the culture supernatants of U- 937 cells and human monocytes stimulated in vitro by certain soluble inflammatory mediators (Sitrin et al, Blood 84:1268, 1994; Mizukami et al., Clin Res 42:115A, 1994). To determine if suPA-R exists in vivo, we have screened the plasma of 20 normal volunteers (mean +/- SD, 3 +/- 3 ng/mL; median, 2 ng/mL; range, 1 to 11 ng/mL [serum values slightly higher]); the plasma of 13 ICU patients with clinical sepsis syndrome (mean +/- SD, 30 +/- 11 ng/mL; median, 11 ng/mL; range, 4 to 221 ng/mL); and the extravascular fluids (pleural, pericardial, and peritoneal) of 84 individuals with presumed inflammatory or malignant conditions (mean +/- SD, 21 +/- 39 ng/mL; median, 10 ng/mL; range, 2 to 253 ng/mL). Among the latter specimens, most were inflammatory exudates (only six were malignant by positive cytology) with the highest quantities of suPA-R associated with neutrophilic exudates. The solubility of suPA-R contained within these fluids was confirmed by reanalysis after ultracentrifugation to remove particulate material. When tested in a uPA ligand capture ELISA, representative specimens of extravascular body fluids and sepsis plasma contained suPA-R capable of binding uPA ligand (generally representing a small fraction of the immunoreactive material). We conclude from these data that suPA-R is immunologically detectable in vitro and in vivo with high concentrations of receptor found under conditions of inflammatory stimulation. The possibility of suPA-R's biologic activity is suggested by its partial retention of ligand binding capacity.     

The role of corticosteroids in severe community-acquired pneumonia: a systematic review

Introduction  

The purpose of this review was to evaluate the impact of corticosteroids on the outcomes of patients with severe community-acquired pneumonia (CAP).     

The clinical picture of ectasia of the intracerebral arteries

Thirty-one patients with ectasia of intracranial arteries were studied. The carotid system was more frequently involved than the vertebrobasilar. The condition is relatively rare and usually occurs with other vascular disease. Ectasia presents with a variety of neurological symptoms, amongst which visual disorders are common. The overall mortality was 52%, but the prognosis was appreciably worse for the vertebrobasilar group, probably because of a higher incidence of compression of surrounding neural structures. Defects in the internal elastic lamina, with or without associated atheroma, are often found in the affected arteries.     

Prevalence of hepatitis C virus and genotype distribution in an Australian volunteer blood donor population

BACKGROUND: This study was undertaken to assess the prevalence of hepatitis C virus (HCV) antibody and RNA in first-time blood donors and to examine the HCV genotype distribution. STUDY DESIGN AND METHODS: A third-generation enzyme-linked immunosorbent assay (ELISA) was used to screen 34,725 donors for HCV antibodies. Donors who were repeatably reactive were tested in two immunoblot assays-a second-generation and a third-generation recombinant immunoblot assay-as well as by a polymerase chain reaction (PCR) assay. PCR-positive donors were genotyped. All samples were screened for alanine aminotransferase levels. RESULTS: The ELISA repeat reactivity rate was 0.55 percent. PCR testing showed that 69 (38%) of the 183 ELISA-reactive samples contained HCV RNA. The third-generation recombinant immunoblot assay identified all 69 viremic samples as antibody positive; however, only 63 tested positive on the second-generation immunoblot. The remaining six PCR-positive donors tested antibody-indeterminate to the core peptide. All six of these donors had HCV subtype 3a infections. Genotype distribution among 58 samples showed that 34 were type 1, of which 22 could be further subtyped as 1a (16) and 1b (6); 2 were 2a; 5 were 2b; and 17 were subtyped as 3a. Donors infected with 2b and 3a had reduced antibody reactivity to the NS4 and NS3 peptides only on the second-generation immunoblot. CONCLUSION: The prevalence of confirmed anti-HCV and viral RNA in new donors is 0.29 and 0.2 percent, respectively. The third-generation recombinant immunoblot assay was more sensitive than the second-generation immunoblot assay in detecting 2b and 3a HCV subtypes. The inclusion of the NS5 peptide in the third- generation recombinant immunoblot did not result in positive tests in any additional donors. Rather, the improvement was due to the increased detection of NS3 and, to a lesser extent, NS4 antibodies. Subtypes 1a and 3a were most prevalent in this population.     

Molecular chaperones enhance the degradation of expanded polyglutamine repeat androgen receptor in a cellular model of spinal and bulbar muscular atrophy

Spinal and bulbar muscular atrophy (SBMA) is one of a growing number of neurodegenerative diseases caused by a polyglutamine-encoding CAG trinucleotide repeat expansion, and is caused by an expansion within exon 1 of the androgen receptor (AR) gene. The family of polyglutamine diseases is characterized by the presence of ubiquitinated, intranuclear inclusions associated with molecular chaperones and 26S proteasome components, although the role of these inclusions in the pathogenesis of polyglutamine diseases remains unclear. The over-expression of molecular chaperones of the Hsp70 and Hsp40 families has been shown to modulate inclusion frequency and cellular toxicity. We developed a cell culture system which enables the quantitative analysis of the effects of molecular chaperones on the biochemical properties of an expanded repeat AR. Using this approach, we demonstrate that Hsp70 and its co-chaperone Hsp40 not only increase expanded repeat AR solubility, but function to enhance the degradation of expanded repeat AR through the proteasome. Furthermore, our studies indicate that these molecular chaperones significantly decrease the half-life of an expanded repeat AR. Molecular chaperone enhancement of protein degradation points to the modulation of molecular chaperones as a potential therapeutic target for polyglutamine diseases.