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Biomedical subjects

F J Morgan

Publications and source records attributed to F J Morgan.

At least 55 records · Page 3Linked to original sources
PubMed1982

Further observations on the effects of dietary fatty acid composition on platelet reactivity and blood coagulation in man and the influence of methodology on findings.

Eight human subjects were fed diets enriched in saturated fat (SF), or polyunsaturated fat (PUF) and after each dietary regimen the plasma heparinthrombin clotting time (HTCT) was determined. The HTCT of citrated plasma indicated reduced heparin-neutralizing activity (HNA) after PUF feeding compared with SF feeding. Platelet factor 4 (PF4) levels in the citrated plasma samples demonstrated an inverse correlation with the HTCT (r = 0.62). Experiments with purified PF4 indicated that the PF4 present in citrated plasma could only account for approximately 10% of the HNA. Plasma prepared in a manner which minimized in vitro release of platelet constituents contained significantly less PF4 after PUF feeding and indicated that most of the PF4 found in citrated plasma resulted from in vitro release. The factor Xa inhibitory activity of citrated plasma was not significantly altered by either of the dietary regimens.

Adult↗
PubMed1982

Amino acid sequence of a basic blue protein from cucumber seedlings.

The amino acid sequence of a type 1 copper protein, the 96-residue basic blue protein from cucumber seedlings, has been determined by Edman degradation of the intact molecule and of fragments produced by cleavage with cyanogen bromide and with trypsin. The cucumber basic blue protein shows a marked sequence homology with stellacyanin, and to a smaller degree with plastocyanin and azurin. The known copper ligands of plastocyanin and azurin (corresponding to histidine-37, cysteine-84, histidine-87, and methionine-92 in plastocyanin) are present in the cucumber basic blue protein. However, the latter also contains a half-cystine residue analogous to the suggested fourth ligand of stellacyanin, where methionine is absent.

Journal Article↗
PubMed1982

Platelet function in coronary artery disease: effects of coronary surgery and sulfinpyrazone.

Platelet survival and plasma concentrations of beta thromboglobulin and platelet factor 4 were measured in 44 patients before and 6 months after coronary artery bypass grafting. Postoperatively, patients were randomized to receive sulfinpyrazone, 800 mg/day, or placebo. Preoperatively, platelet survival was significantly shorter than normal, and plasma concentrations of both platelet-specific proteins were significantly elevated. Postoperatively, all three indexes of platelet function tended to become normal, but these changes were statistically significant only in patients treated with sulfinpyrazone. Postoperative exercise testing correlated significantly with plasma concentrations of beta thromboglobulin and platelet factor 4 measured preoperative and postoperative. These results are consistent with reports of the effects of sulfinpyrazine on platelet involvement in other conditions, and suggest that the drug reduces platelet activation and inhibits actual destruction. The results also show a relationship between abnormalities of platelet function and an index of postoperative myocardial ischemia.

Angina Pectoris↗
PubMed1982

Adrenocorticotropin, beta-endorphin, and beta-lipotropin in normal thyroid and lung: possible implications for ectopic hormone secretion.

The expression of the proopiomelanocortin (POMC) gene by normal lung and thyroid was examined by measurement of the content of ACTH, beta-lipotropin (beta LPH), and beta-endorphin (beta EP) in porcine lung and thyroid tissue. Acid extracts of normal porcine lung and thyroid tissue each contained appreciable amounts of immunoreactive (ir) ACTH, ir-beta LPH, and ir-beta EP. The content of ir-beta LPH in both tissues exceeded by severalfold, on a molar basis, the content of ir-ACTH and ir-beta EP, suggesting that the common precursor POMC was processed predominantly to peptides other than ir-ACTH and ir-beta EP. A porcine thyroid extract (Calcitare, porcine calcitonin, Armour) showed equivalent levels of beta EP-like immunoreactivity and bioactivity, measured by opiate radioreceptor assay; in contrast, ACTH-like bioactivity, measured by rat zona fasciculata steroidogenesis, was only 4% of ACTH-like immunoreactivity. On reversed phase high performance liquid chromatography, Calcitare showed multiple peaks of ACTH-like immunoreactivity, one of which coeluted with porcine ACTH-(1-39), and two much smaller peaks of beta EP-like immunoreactivity, of which the smaller coeluted with porcine beta EP. These data suggest that both lung and thyroid gland synthesize POMC, which in normal tissue is usually predominantly processed to species other than ACTH and beta EP. Ectopic secretion of ACTH and beta EP by lung and thyroid neoplasms may thus represent the loss of a system(s) normally responsible for processing the precursor beyond ACTH and beta EP.

Adrenocorticotropic Hormone↗
PubMed1980

Complete covalent structure of human platelet factor 4.

The amino acid sequence of the subunit of human platelet factor 4 has been determined. Human platelet factor 4 consists of identical subunits containing 70 amino acids, each with a molecular weight of 7,756. The molecule contains no methionine, phenylalanine or tryptophan. The proposed amino acid sequence of PF4 is: Glu-Ala-Glu-Glu-Asp-Gly-Asp-Leu-Gln-Cys-Leu-Cys-Val-Lys-Thr-Thr-Ser-Gln-Val-Arg-Pro-Arg-His-Ile-Thr-Ser-Leu-Glu-Val-Ile-Lys-Ala-Gly-Pro-His-Cys-Pro-Thr-Ala-Gln-Leu-Ile-Ala-Thr-Leu-Lys-Asn-Gly-Arg-Lys-Ile-Cys-Leu-Asp-Leu-Gln-Ala-Pro-Leu-Tyr-Lys-Lys-Ile-Ile-Lys-Lys-Leu-Leu-Glu-Ser. From consideration of the homology with beta-thromboglobulin, disulphide bonds between residues 10 and 36 and between residues 12 and 52 can be inferred.

Amino Acid Sequence↗
PubMed1980

Plasma concentrations of platelet-specific proteins correlated with platelet survival.

Relationships between 51Cr platelet survival and plasma concentrations of beta-thromboglobulin (betaTG) and platelet factor 4 (PF4) were analyzed in 91 studies of patients with coronary artery disease. betaTG was significantly correlated with platelet life-span, turnover, and the number of hits in the multiple hit model. PF4 was significantly correlated with life-span and turnover. The most significant relationship involving platelet-specific protein concentrations and life-span estimates was between betaTG and life-span estimated using the multiple hit model (r = -0.39, p less than 0.001). There was a high correlation between betaTG and PF4 (r = 0.62, p less than 0.001), and no improvement could be obtained by combining the measurements of the two proteins in any regression with life-span or turnover. The results indicate that the patients with the shortest platelet survival time in this group tended to have the highest plasma concentration of betaTG and PF4 and thus probably increased in vivo release of betaTG and PF4. They strengthen the claim that these platelet-specific proteins may be indicators of platelet involvement in disease.

Blood Platelets↗
PubMed1979

Structural and antigenic studies of an idiotype-bearing murine antibody to the arsonate hapten.

Mice of strain A/J responded to repeated intraperitoneal injection of Limulus hemocyanin derivatized with arsanilic acid by producing large quantities (approximately 5 mg/mL of ascites fluid) of IgG antibodies specific for this hapten. The antibodies possessed a characteristic idiotypic determinant and exhibited restricted heterogeneity as demonstrated by isoelectric focusing and primary N-terminal amino acid sequence analysis of isolated light and heavy polypeptide chains. Both light- and heavy-chain sequences were comparable to those of myeloma proteins in lack of heterogeneity. The N terminus of the light chain exhibited V KI sequence and only one position in the first 30 residues showed more than one amino acid. No variability was observed in the first 10 N-terminal residues of the heavy chain. Rabbit antiserum to the idiotype blocked binding of hapten by the purified antibody. The presence of both light- and heavy-chain antigenic determinants was required for optimal formation of the idiotypic determinant.

Amino Acid Sequence↗
PubMed1978

Complete covalent structure of human beta-thromboglobulin.

The complete primary structure of the platelet-specific protein human beta-thromboglobulin has been determined. beta-Thromboglobulin consists of identical subunits of 81 amino acids, each with a molecular weight of 8851. The amino acid sequence of the beta-thromboglobulin subunit is: Gly-Lys-Glu-Glu-Ser-Leu-Asp-Ser-Asp-Leu-Tyr-Ala-Glu-Leu-Arg-Cys-Met-Cys-Ile-Lys-Thr-Thr-Ser-Gly-Ile-His-Pro-Lys-Asn-Ile-Gln-Ser-Leu-Glu-Val-Ile-Gly-Lys-Gly-Thr-His-Cys-Asn-Gln-Val-Glu-Val-Ile-Ala-Thr-Leu-Lys-Asp-Gly-Arg-Lys-Ile-Cys-Leu-Asp-Pro-Asp-Ala-Pro-Arg-Ile-Lys-Lys-Ile-Val-Gln-Lys-Lys-Leu-Ala-Gly-Asp-Glu-Ser-Ala-Asp. Disulfide bridge-18 to half-cystine-58. The amino acid sequence of beta-thromboglobulin shows a marked homology with that of platelet factor 4. When the sequences are aligned for maximum homology, 42 of the 81 residues of beta-thromboglobulin are identical with those of platelet factor 4, including the position of the four half-cystines.

Amino Acid Sequence↗
PubMed1978

Obituary.

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Amino Acid Sequence↗
PubMed1978

Plasma levels of platelet factor 4 measured by radioimmunoassay.

A radioimmunoassay has been developed to measure platelet factor 4 (PF4) in biological fluids both in vitro and in vivo. The assay has been shown to be highly specific for PF4 and has a sensitivity of 0.08 ng/assay tube and 1.6 ng/ml of plasma. The preparation of plasma for the measurement of in vivo levels of PF4 requires the use of an anticoagulant containing EDTA, theophylline and prostaglandin E1, the immediate cooling of the blood and high speed or prolonged centrifugation to reduce platelet contamination. Plasma levels of PF4 are normally between 4 and 24 ng/ml with a median of 7.4 ng/ml. Plasma PF4 levels are markedly increased during cardiopulmonary bypass surgery with shortened 51Cr-labelled platelet survival times and during arterial thrombosis. However, despite similarly shortened platelet survival times, the level of PF4 is normal in immune thrombocytopenia. Elevations of plasma PF4 levels are found following surgery, acute myocardial infarction and frequently during acute infections and in inflammatory states. On the contrary, normal levels are usual in disseminated malignancy, in severe hepatic and renal disease and in chronic arterial disease. The measurement of PF4 is a useful addition to the study of platelet pathophysiology. It is apparent, however, that raised levels are by no means specific for thromboembolic disease and similarly platelet destruction is not invariably associated with abnormally increased plasma PF4 levels.

Adult↗
PubMed1977

Studies on the chemistry of human platelet factor 4.

The chemical characteristics of several PF4 preparations have been examined by gel electrophoresis, amino acid analysis and NH2-terminal amino acid sequence determination. Preparations of PF4 from gel filtration and from affinity chromatography appeared identical. A single NH2-terminal sequence was determined as follows: NH2-Glu-Ala-Glu-Glu-Asp-Gly-Asp-Leu-Gin-SCMCys-Leu-SCMCys-Val-Lys-Thr-Thr-Ser-Gln-Val-Arg-. The molecular weight of the PF4 subunits, which seem to be identical, was 7,100 based on the recovery of NH2-terminal glutamic acid.

Amino Acid Sequence↗
PubMed1976

Enzyme reduction of disulfide bonds by thioredoxin. The reactivity of disulfide bonds in human choriogonadotropin and its subunits.

The NADPH-dependent enzymic reduction of disulfide bonds in human choriogonadotropin and its two subunits, alpha and beta, was examined with thioredoxin and thioredoxin reductase from Escherichia coli. With 12 muM thioredoxin and 0.1 muM thioredoxin reductase at pH 7 all disulfide bonds in the alpha subunit could be reduced in 15 min. The reduction of disulfide bonds was recorded by a simple spectrophotometric assay at 340 nm, which allowed quantitation of the reduction rate and the number of disulfide bonds reduced. Partial reduction of the alpha subunit with thioredoxin followed by S-carboxymethylation with iodol[2-3H]acetic acid and analysis of tryptic peptides indicated that all S-S bonds in the alpha subunit were surface oriented and equally reactive. The usefulness of thioredoxin reduction of disulfide bonds as a chemical probe of protein structure was shown by the much slower reaction of disulfide bonds in the intact hormone as compared to its two biologically inactive subunits.

Aerobiosis↗