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At least 181 records · Page 10Linked to original sources
PubMed1993

Presentation of a circulating self protein (C5) to MHC class II restricted T cells.

Presentation of a soluble self antigen, the fifth component of complement (C5), is discussed with emphasis on the differential ability of presentation by subpopulations of APC (dendritic cells, macrophages, B cells, fibroblasts, B cell lines and bone marrow macrophages). Constitutive presentation of C5 in C5 sufficient mice is a prerequisite for tolerance induction in MHC class II restricted T cells and can be directly demonstrated by the ability of ex-vivo APC from C5 sufficient, but not C5 deficient mice, to activate C5 specific T cells in vitro in the absence of added antigen. C5 presentation and tolerance induction in MHC class II restricted T cells is strictly dependent on an exogenous source of self antigen. C5 biosynthesized, but not secreted by macrophages is ignored by MHC class II restricted cells and induces neither tolerance nor autoimmunity. C5 presentation for tolerance induction depends largely on the efficiency of antigen uptake by APC, a property which varies within different APC subpopulations and with the nature of the antigen.

Animals↗
PubMed1992

Perspective: measurement of circulating glycated proteins to monitor intermediate-term changes in glycaemic control.

The effective clinical management of diabetes requires accurate means to measure and monitor prevailing blood glucose concentrations. This can be accomplished with regular home glucose monitoring and periodic measurement of indicators that reflect ambient glycaemia during defined temporal intervals. The amount of glycated haemoglobin provides an index of integrated long-term glycaemia, whereas the amount of glycated albumin provides an index of short to intermediate term integrated glycaemic control. However, there is confusion regarding the various methods for estimation of glycated serum or plasma proteins, in part because the different methods use different reaction principles, measure different substances, and express results in different units. This article reviews the principles underlying different assays for measurement of glycated albumin and glycated serum proteins, compares their ranges of values, and discusses their clinical relevance assessed by studies published in the recent medical literature. The methods evaluated include commercially available assays for measuring glycated albumin with monoclonal antibodies and with affinity chromatography (including HPLC), and the fructosamine assay for glycated serum proteins.

Antibodies, Monoclonal↗
PubMed1953

Fluorescein-conjugated bovine albumin; physical and biological properties.

Fluorescein-bovine albumin conjugates have been prepared and found not to differ appreciably in size, shape, and homogeneity from the precursor, bovine serum albumin. Fluorescein has also been conjugated to rat plasma proteins. Their disappearance rates from the circulation of rats correspond with those obtained from the use of isotope labeling. Their sites of localization in rat tissues were shown to be in the cytoplasm but not in the nuclei of Kupffer cells, fixed macrophages, granulocytes, and proximal renal tubules. Adsorption to endothelium was a characteristic finding. Extracellular localizations were predominantly in the lumina of blood vessels and proximal renal tubules (but never in the lumina of collecting tubules), and the interstitial fluid of skeletal and cardiac muscle (but not that of glandular organs such as the adrenals, liver, and spleen). BAC absorption from the skin of rabbits requires days whereas sodium fluorescein absorption is measured in hours, attesting to the persistence of the colloidal state of BAC in vivo. Fluorescein conjugates have been used to visualize the transcapillary passage of circulating proteins in the mesenteric circulation of frogs and rats by direct microscopic observation and found to diffuse slowly in the manner predicted for plasma proteins. The normal cutaneous vessels of the rat are impermeable in the gross to the labeled proteins; second degree burn promptly increases the permeability of these vessels rendering the presence of the label detectable in the gross in the skin. The process of labeling does not render guinea pig albumin antigenic, although slight antigenicity results from labeling whole plasma protein. It is believed that sufficient biological evidence is presented to support the conclusion that fluorescein-conjugated plasma proteins, particularly albumin, behave in vivo like their native precursors.

Animals↗
PubMed1982

Radioimmunoassay for pregnancy-associated plasma protein A.

A specific and highly sensitive radioimmunoassay for determination of pregnancy-associated plasma protein A in human serum is described. The minimum detection limit for this protein was 2.9 micrograms/L. The within- and between-assay coefficients of variation were 4.0 and 4.5%, respectively. The circulating protein was detected within 32 days of conception in eight normal pregnancies and within 21 days in a twin pregnancy. Circulating concentrations in the mother at term were consistently higher (10-fold) than in matched amniotic fluid; none was detected in the umbilical circulation. This protein was also detected in the circulation of patients with hydatiform mole. This assay will permit investigations into the clinical evaluation of measurements of the protein during early pregnancy and trophoblastic disease.

Amniotic Fluid↗
PubMed1991

A multicentre controlled clinical trial of high-volume fresh frozen plasma therapy in prognostically severe acute pancreatitis.

Fresh frozen plasma (FFP) has been proposed as a specific therapy for acute pancreatitis. It may replenish important circulating proteins, particularly the naturally occurring anti-protease system. To investigate this potential therapy, 72 patients with predicted severe disease were selected from 301 admissions with acute pancreatitis using the modified Glasgow prognostic scoring system. They were randomised within 6 h of diagnosis to receive FFP (8 units daily for 3 days) or a similar volume of colloid control as part of their intravenous fluid therapy. Clinical progress was monitored and specific blood proteins were measured on days 1, 3 and 7. FFP therapy significantly increased the day 3 concentrations of some of the acute phase proteins (C1-reactive protein P less than 0.02, D-dimer P less than 0.05 and fibrinogen P less than 0.05) as well as some proteins which showed a fall in circulating concentration during the early stages of the disease (alpha 2 macroglobulin P less than 0.001, antithrombin III P less than 0.01 and fibronectin P less than 0.001). However, there was no significant difference between the two groups in terms of clinical outcome. Mortality was 20% in patients who received FFP and 18% in the colloid control group. Despite the ability of FFP therapy to supplement circulating concentrations of several potentially useful proteins during acute pancreatitis, it does not appear to improve clinical outcome.

Acute Disease↗
PubMed1983

Quantification of corticosteroid binding globulin by electroimmunoassay during human pregnancy.

Corticosteroid binding globulin (CBG) was purified by one step positive immunospecific affinity chromatography and antibody to human CBG produced in goats. The goat anti-human CBG was used in the development of a precise rocket immunoelectrophoresis for CBG quantification. CBG levels measured by this assay were found to increase from 30 AU/ml to 100 AU/ml during pregnancy. There was no statistically significant association observed between levels of CBG, or circulating estriol, or pregnancy zone protein. Circulating CBG was estimated in 32 women with pregnancy associated hypertension, the levels were all within the normal range, and not significantly different from those seen in matched controls.

Animals↗