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Biomedical subjects

M B Pepys

Publications and source records attributed to M B Pepys.

At least 217 records · Page 12Linked to original sources
PubMed1983

Immunohistochemical studies of amyloid P component distribution in normal human skin.

The distribution of amyloid P component (AP) in normal human skin was investigated by a light and electron microscopic immunoperoxidase technique, using antibodies to serum amyloid P component (SAP). AP, or an immunologically cross-reactive protein, was found to be specifically localized to the microfibrils of papillary oxytalan fibers and to the peripheral microfibrillar mantle surrounding the elastin core of mature elastic fibers in the reticular dermis; collagen fibers were not stained with anti-SAP. AP was not detected in the dermal-epidermal basement membrane or in the basement membranes surrounding dermal papillary blood vessels and eccrine structures. These findings, which establish the detailed distribution of normal tissue AP in the skin, provide a basis for further studies of the function and behavior of this protein in health and disease.

Amyloid↗
PubMed1983

Immunohistochemical studies of amyloid P component and fibronectin in erythropoietic protoporphyria.

Immunofluorescence staining of exposed skin from patients with erythropoietic protoporphyria (EPP) with antibodies to serum amyloid P component (SAP) and to fibronectin produced striking fluorescence of abnormal vascular structures in the upper dermis. An appearance of linear fluorescence along the dermo-epidermal junction with anti-SAP was the result of confluent staining of papillary oxytalan fibres. Amyloid P component (AP) was localized in ultrastructural immunoperoxidase studies to the peripheral (abluminal) regions of thickened dermal vessel walls, the site of maximum concentration of an amorphous matrix containing microfibrillar structures; antibodies to SAP did not bind to leaflets of the reduplicated vascular basal lamina. The characteristic thickening and reduplication of blood vessel walls seen with the electron microscope in EPP therefore involves increased local deposition of both AP and fibronectin.

Amyloid↗
PubMed1983

Plasma haemostatic factors and diabetic retinopathy.

Plasma coagulation factors were measured in twelve male insulin-dependent diabetics with no retinopathy, ten with background and ten with proliferative retinopathy and ten non-diabetics. Factor VIII pro-coagulant activities (VIII:C), ristocetin cofactor activities and factor VIII-related antigen concentrations (VIIIR:ag) were significantly related to the severity of diabetic retinopathy (P less than 0.025, trend test). The mean ratio of VIII:C/VIIIR:ag was lower in the diabetics with proliferative retinopathy than in the other groups of diabetics (P less than 0.05) or the controls (P less than 0.02). Concentrations of alpha 2 macroglobulin and alpha 1 antitrypsin were highest in diabetics with proliferative retinopathy (0.1 greater than P greater than 0.05, trend test) but mean prothrombin and activated partial thromboplastin times and mean concentrations of alpha 2 antiplasmin, plasminogen activator and antithrombin III were similar in all groups. Concentrations of the platelet-specific protein beta thromboglobulin, though higher in diabetics than controls (P less than 0.005), were not related to retinopathy. The plasma concentrations of coagulation factors did not correlate with creatinine clearance and there were no significant differences between groups in concentrations C-reactive protein; this suggests that the raised concentrations of coagulation factors in diabetics with retinopathy were not a result of associated nephropathy or an 'acute phase protein' response to diabetic tissue damage. Increased coagulation activity in diabetics may contribute to the development of retinopathy.

Adult↗
PubMed1983

Anti-keratin antibodies in rheumatoid arthritis: frequency and correlation with other features of the disease.

Anti-keratin antibodies (AKA) were detected in 68 out of 98 patients (69%) with classical or definite rheumatoid arthritis (RA). The intensity of the AKA reaction correlated significantly with articular index (AI), grip strength (GS), erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP) concentration, serum amyloid A (SAA) protein concentration, the level of antibodies against single stranded DNA (ssDNA) and the IgM rheumatoid factor (RF) titre. A significantly higher number of patients with nodules and Sjögren's syndrome were AKA positive compared with patients without extra-articular features (EAFs) and the AKA titre was significantly greater in the former group. The mechanisms underlying appearance of AKA are not known but may relate to an as yet unidentified structural alteration of keratin in this disease or may just reflect the rheumatoid autoimmune diathesis.

Adult↗
PubMed1983

Quantitative fecal indium 111-labeled leukocyte excretion in the assessment of disease in Crohn's disease.

The assessment of disease activity in Crohn's disease involves determination of either clinical indexes (e.g., Crohn's disease activity index) or laboratory measurements (e.g., C-reactive protein and erythrocyte sedimentation rate). These have the disadvantage of being indirect and nonspecific correlates of gut inflammation. We have assessed disease activity in Crohn's disease by measurement of fecal leukocyte excretion after intravenous administration of either 111In-labeled mixed leukocyte or pure granulocyte preparations. With mixed leukocyte preparations, fecal excretion of radioactivity correlated with Crohn's disease activity index (r = 0.78, p less than 0.001) and C-reactive protein (r = 0.74, p less than 0.01). Using pure granulocytes, fecal 111In excretion (range 1.5%-52%) was much higher than with mixed leukocytes (range 0.1%-11.0%), showing significant correlations with Crohn's disease activity index (r = 0.731, p less than 0.001), C-reactive protein (r = 0.716, p less than 0.001), and erythrocyte sedimentation rate (r = 0.676, p less than 0.001). Quantitative fecal excretion of 111In-leukocytes is a new method of assessing disease activity in Crohn's disease, specific for bowel inflammation and suitable for objective assessment of disease activity in therapeutic trials.

Blood Sedimentation↗
PubMed1982

Solid-phase immunoradiometric assay for serum amyloid A protein using magnetisable cellulose particles.

An immunoradiometric assay for human serum amyloid A protein (SAA) was developed using magnetisable cellulose particles as the solid phase. Rabbit antiserum to to SAA was raised by immunization with SAA isolated from acute-phase serum by gel filtration in formic acid. The antiserum was rendered monospecific for SAA by solid-phase immunoabsorption with normal human serum, which contains only traces of SAA, and some was coupled covalently to the cellulose particles. Immunopurified anti-SAA antibodies were isolated from the monospecific anti-SAA serum by binding to, and elution from insolubilized acute-phase serum and were radiolabelled with 125I. The assay was calibrated with an acute phase serum which contained 6000 times more SAA than normal sera with the lowest detectable level of SAA, and an arbitrary value of 6000 U/l was assigned to this standard. Sera were tested in the native, undenatured state and there was no increase in SAA immunoreactivity following alkali treatment or heating. The assay range was from 1-2000 U/l so that all SAA levels above 6 U/l could be measured on a single (1:6) dilution of serum. The intra- and interassay coefficients of variation were 11.7 and 15.0% respectively. Among 100 healthy normal subjects (50 male, 50 female) the median SAA level was 9 U/l, range less than 1-100, with 93% below 20 U/l and only 2% below the lower limit of sensitivity of the assay (1 U/l).

Adolescent↗
PubMed1982

The acute-phase response in (NZB X NZW)F1 and MRL/l MICE.

The acute-phase plasma protein response to disease activity in murine models of autoimmune lupus-like disease was investigated by measurement of the concentration of serum amyloid P component (SAP) in NZB X W and MRL/l mice. The levels of SAP, which is a major acute-phase protein in mice, did not rise at all in response to progression of disease in NZB X W mice between the ages of 1 and 9 mo. This resembles the behavior of acute-phase proteins such as C-reactive protein and serum amyloid A protein in human systemic lupus erythematosus, and just as in human lupus, where the occurrence of intercurrent microbial infection can stimulate an acute-phase response, so injection of bacterial lipopolysaccharide or casein into the NZB X W mice stimulated "normal" acute-phase SAP production. In marked contrast, MRL/l mice developed greatly increased levels of SAP, which correlated closely with progression of their pathology as they aged. The disease profile of the MRL/l strain includes rheumatoid factors and spontaneous polyarthritis and their SAP response resembles the behavior of acute phase proteins in human rheumatoid arthritis. Different patterns of acute-phase response in different autoimmune disorders may thus be a reflection of the genetic predisposition to particular diseases and/or contribute to their pathogenesis. The existence of animal counterparts for the various clinical patterns of human acute-phase protein production will assist in experimental investigation of the underlying mechanisms and of the biological role of the acute-phase response.

Amyloid↗
PubMed1982

Serum amyloid-A protein concentration in inflammatory diseases and its relationship to the incidence of reactive systemic amyloidosis.

Serum amyloid-A protein (SAA) is the putative precursor of amyloid-A (AA) protein which forms the fibrils in reactive systemic or secondary amyloidosis. By means of a novel immunoradiometric assay, the concentration of SAA was found to be greatly elevated in patients with rheumatoid arthritis and juvenile chronic arthritis and correlated with activity of their primary disease. However, in patients with systemic lupus erythematosus SAA levels were only modestly raised, even in those with severe active disease, unless significant intercurrent microbial infection was also present. In Crohn's disease SAA levels showed a pattern similar to that seen in rheumatoid arthritis, whereas in ulcerative colitis it resembled that of systemic lupus erythematosus. The level of SAA response in these different disorders corresponds with the incidence of reactive systemic amyloidosis in them. These observations support the view that major increases in SAA levels are a necessary condition for the deposition of this form of amyloid and suggest that prospective monitoring of the SAA concentration in predisposing diseases may help to identify those individuals who are most at risk for amyloidosis.

Amyloid↗
PubMed1982

Low density lipoprotein and very low density lipoprotein are selectively bound by aggregated C-reactive protein.

C-reactive protein (CRP), the classical acute-phase protein, can bind phospholipids by virtue of its specific, calcium-dependent reactivity with phosphorylcholine residues. However, analysis of acute-phase serum by gel filtration and by density gradient ultracentrifugation showed that the CRP was in a free, uncomplexed form, despite the coexistent presence of the various classes of serum lipoproteins, all of which contain phospholipids. In contrast, when isolated CRP was aggregated by immobilization at a sufficient density on a solid phase and then exposed to normal human serum, it selectively bound low density lipoprotein (LDL) and traces of very low density lipoprotein. The reaction was calcium dependent and reversible by free phosphorylcholine but not by heparin. LDL isolated from normal plasma was also bound by aggregated CRP. CRP reacts in vitro with a wide variety of different ligands both of extrinsic and of autogenous origin, e.g., microbial products and damaged cell membranes, respectively. If CRP aggregated in vivo by complexing with these ligands than acquires the capacity to selectively bind LDL, the phenomenon may have significant implications for the function of CRP and for the metabolism, clearance, and deposition of LDL.

Acute Disease↗
PubMed1982

C-reactive protein and serum amyloid P component in the plaice (Pleuronectes platessa L.), a marine teleost, are homologous with their human counterparts.

C-reactive protein and serum amyloid P component were isolated from serum of the plaice (Pleuronectes platessa L.), a murine teleost. The isolation was based on their calcium-dependent binding affinity for pneumococcal C-polysaccharide and for agarose, respectively. These specificities are the same as those of human C-reactive protein and serum amyloid P component, respectively, and we have previously reported that the plaice molecules resemble human C-reactive protein and serum amyloid P component in their electron microscopic appearance. We describe here estimation of the molecular weights of plaice C-reactive protein and serum amyloid P component and their subunits, and analysis of their amino acid composition, glycosylation and partial amino-terminal amino acid sequences. The results establish that plaice C-reactive protein and serum amyloid P component are homologous with each other and with their human counterparts and indicate that there has been stable conservation of this protein family throughout vertebrate evolution.

Amino Acid Sequence↗
PubMed1982

Calcium-dependent aggregation of human serum amyloid P component.

Normal human serum or isolated human amyloid P component was ultracentrifuged on density gradients containing either 10 mM EDTA or different concentrations of Ca2+ between 0.15 and 2.15 mM. In the presence of Ca2+ concentrations of 1 mM or more human P component sedimented more rapidly than it did in the presence of lower Ca2+ levels or of EDTA. This phenomenon was due to Ca2+-dependent aggregation of P component molecules and did not require the presence of any other serum constituents. It was completely inhibited by incorporating a physiological concentration (40 mg/ml) of serum albumin in the gradients, suggesting that free ionized Ca2+ is required to promote aggregation of the P component. P component from the mouse and the plaice (Pleuronectes platessa L.), a marine teleost, did not undergo the same Ca2+-dependent aggregation as human P component. These observations resolve a discrepancy existing in the literature concerning the sedimentation rate of human P component in density gradient ultracentrifugation and shed new light on its behaviour with respect to Ca2+ which may be relevant to the deposition of P component in amyloidosis.

Amyloid↗
PubMed1982

Solid-phase immunoradiometric assay for C-reactive protein using magnetisable cellulose particles.

An immunoradiometric assay (IRMA) for C-reactive protein (CRP) was developed using magnetisable cellulose particles as the solid-phase support for anti-CRP antibodies. 125I-labeled immunopurified anti-CRP antibody was used to quantitate the amount of CRP taken up by the solid phase. Unbound label was easily and rapidly removed by decantation after sedimenting the particles on a magnet. The assay could detect 1 microgram CRP/l and had a range of up to 10 mg/l with the portion of the standard curve between 10 micrograms/l and 2-3 mg/l being linear. Fifty samples per hour could be processed manually from serum to CRP result with an intra-assay CV of 5.2% and an inter-assay CV of 10.0%, based on 5 replicates of 5 samples with CRP levels between 2 mg/l and 180 mg/l run in 5 separate assays. Fifty clinical samples were assayed in parallel with a standard electroimmunoassay and yielded a linear correlation coefficient (r) of 0.975 and a slope of 0.988. With its single, brief incubation step including all reagents and its simple phase separation procedure the present method may be the assay of choice when precise measurement of CRP concentrations is required rapidly.

Animals↗