Search PubMed⌕ Search

Biomedical subjects

F C De Beer

Publications and source records attributed to F C De Beer.

27 records · Page 2Linked to original sources
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↗
PubMed1982

Isolation of human C-reactive protein and serum amyloid P component.

Procedures are described for the isolation in high yield of consistent, highly purified preparations of human C-reactive protein (CRP) and serum amyloid P component (SAP). CRP was obtained from malignant ascitic and pleural fluids by calcium-dependent affinity chromatography on pneumococcal C-polysaccharide covalently coupled to cyanogen bromide-activated Sepharose. It was then gel filtered on Ultrogel AcA44 (acrylamide-agarose beads) in the presence of calcium ions, combining molecular sieve chromatography with removal of contaminating SAP by its affinity of agarose. Residual trace contaminants were removed by immunoabsorption with anti-normal human serum and anti-SAP antibodies insolubilised on Sepharose and/or by absorption with Sepharose-Con A to remove glycoproteins and Blue-Sepharose to remove albumin. After a final gel filtration step on Sephacryl S-300 35-45% of the initial CRP was recovered in pure form according to biochemical and immunochemical criteria. SAP was isolated from normal serum by calcium-dependent affinity chromatography on unsubstituted Sepharose beads, followed by solid-phase immunoabsorption of contaminants and finally gel filtration on Sephacryl S-300. At least 50% of the SAP in the starting material was recovered in pure form according to biochemical and immunochemical criteria. Ready availability of such preparations facilitates biochemical, biophysical and particularly biological studies of these plasma proteins.

Amyloid↗
PubMed1982

Familial amyloidosis of Ostertag.

A 23 year old Englishman presented with keratoconjunctivitis sicca and was found to have systemic amyloidosis. Five members of his family in two generations also had non-neuropathic amyloid particularly affecting the kidneys. This conforms to the Ostertag type of hereditary amyloidosis. Amyloid deposits in the proband showed permanganate-sensitive Congophilia and positive immunofluorescence staining for P component, but were negative for amyloid A and prealbumin. These observations suggested that the fibril protein in this patient was immunochemically distinct from the amyloid fibrils characterized hitherto.

Adult↗
PubMed1982

Radiometric ligand binding assay for C-reactive protein. Complexed C-reactive protein is not detectable in acute phase serum.

A radiometric ligand binding assay for human C-reactive protein (CRP) was established using pneumococcal C polysaccharide (CPS) coupled to magnetizable cellulose particles as the solid phase ligand. Competition for binding to the solid phase between 125I-CRP and unlabelled CRP permitted detection of 30 micrograms/l of CRP and the precise assay of concentrations up to 3000 micrograms/l. Identical results were obtained when the assay was used to quantitate isolated pure CRP and pure CRP added to normal human serum. However in vitro addition of known ligands for CRP to acute phase serum resulted in lowering of the apparent CRP concentration in this assay and addition of as little as 1 microgram/l of free CPS or 1 mg/l of lecithin was demonstrable in this way. A combination of the ligand binding assay and the standard electroimmunoassay for CRP was therefore used to test acute phase sera for the presence of CRP complexed in vitro. No evidence of complexed CRP was detected among sera containing between 1-319 mg/l of CRP from patients with Hodgkin's disease (10), rheumatoid arthritis (10), Crohn's disease (19) and various microbial infections (11), including six with subacute bacterial endocarditis. Since it is likely that CRP does form complexes with its ligands in the plasma these results suggest that complexed CRP is rapidly cleared from the circulation.

Acute Disease↗
PubMed1981

Human plasma vasopressin response to potent loop-diuretic drugs.

To investigate the effect of potent loop diuretic drugs on the factors that control water excretion, immunoreactive plasma arginine vasopressin was measured at regular intervals for 6 h after intravenous administration of frusemide (40 mg) and piretanide (12 mg) in healthy adults. Despite a large diuresis there was no significant rise in plasma vasopressin compared to controls. Diuretic drug treatment caused small increases in plasma osmolality comparable to the control group, but no change in mean arterial blood pressure. The fall in blood volume of 7% within 1 h of frusemide administration was insufficient to stimulate vasopressin secretion. We conclude that loop diuretic drugs in the dose given have little effect on plasma vasopressin and osmolality but cause a small fall in blood volume in healthy adults.

Adult↗
PubMed1981

Immunohistochemical demonstration of amyloid P component in skin of normal subjects and patients with cutaneous amyloidosis.

The presence of amyloid P component (AP) in dermal deposits of cutaneous amyloidosis was demonstrated by a direct immunofluorescence technique using an antibody to serum amyloid P component (SAP). AP was also shown, for the first time, to be a constituent of normal human skin. It was present at the periphery of dermal elastic tissue fibres, in basement membranes of dermal blood vessels and surrounding eccrine sweat glands but was absent from the dermo-epidermal basement membrane. The staining pattern in cutaneous amyloidosis was morphologically distinctive and readily distinguishable from staining of thickened vascular basement membranes in porphyria. Immunofluorescence with anti-SAP is simple and specific and may become the procedure of choice in the differential diagnosis of amyloidosis.

Amyloid↗