Biomedical subjects
S S Harwig
Publications and source records attributed to S S Harwig.
Studies of beta-thromboglobulin, platelet factor 4, and fibrinopeptide A in erythrocytosis due to cyanotic congenital heart disease.
Plasma and serum assays of beta-thromboglobulin (BTG) and platelet factor 4 (PF4), and plasma fibrinopeptide A (FPA) were measured in adults with cyanotic congenital heart disease to characterize further the hemostatic disorder. Artifactual elevations of plasma BTG, PF4, and FPA appeared to occur occasionally when a 21 or 22 gauge needle was used to collect blood. The high packed red cell volume was probably the cause. Use of a larger caliber needle (20 gauge) appeared to lessen the problem. Normal plasma FPA levels (20 gauge needle) in 8 of 9 patients suggest that chronic intravascular coagulation is not common in these patients. Serum BTG and PF4, used to estimate total platelet content of these proteins, were normal to slightly increased. That levels were not reduced implies that platelets do not usually circulate in a "spent" state. Therapeutic phlebotomy in 8 patients was associated with small decreases in plasma BTG and PF4 of uncertain clinical significance. Five of 14 patients had elevated plasma BTG with normal to only minimally increased plasma PF4. However, 10 of 10 patients tested were found to have reduced creatinine clearance, and therefore the relative contributions of platelet secretion and reduced BTG catabolism in the kidney to elevated plasma BTG levels are unclear.
Solid phase bovine thrombin. Preparation and properties.
A new solid-phase thrombin (EC 3.4.21.5) was prepared through conjugation of the enzyme under mild conditions to a glass support bearing an active ester of N-hydroxysuccinimide. The immobilized enzyme retained 50 +/- 10% of the specific esterase activity of the parent soluble enzyme. The Km (apparent) for the esterase activity of the immobilized enzyme has a value of 5 mM, identical of the Km value of the parent-soluble enzyme. Only 6 +/- 1% of the specific proteolytic activity was retained and a higher Km (apparent) value of 67 muM was obtained for the insoluble enzyme compared to Km value of 12.5 muM for the parent soluble thrombin. Solid-phase thrombin prepared by the diazocoupling technique was previously reported to retain only 3% of the specific proteolytic activity. The observed loss of specific proteolytic activity can be attributed to steric interference, a change in charge characteristics, or both. Nevertheless, the present method of preparation has the advantages of rapidity and simplicity. It can readily be adapted to use for studying the fate of various complexes of fibrinogen, fibrin and their degradation products. It should also be useful for preparing radiolabeled autologous soluble fibrin for thrombus detection in patients undergoing active thrombosis.
Preparation and in vitro properties of 99mTc-fibrinogen.
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In vivo behavior of 99mTc-fibrinogen and its potential as a thrombus-imaging agent.
We have investigated the in vivo behavior of 99mTc-fibrinogen, prepared by a mild and efficient electrolytic method employing tin electrodes. The clearance mechanisms of this agent were studied, and its efficacy for imaging deep-vein thrombi in dogs with an Anger camera was determined. The 99mTc-fibrinogen preparations, which are stable in vitro, undergo partial rapid exchange of the technetium with other plasma proteins and with anions of the blood buffer system in vivo, resulting in an early drop in the percent of radioactivity associated with clottable protein. However, very little or no oxidation to pertechnetate occurs. The nonclottable material is much more rapidly cleared from the blood than the remaining 99mTc-fibrinogen, and the proportion of clottable protein activity increases with time. The fraction of 99mTc-fibrinogen that remains intact in vivo is biologically active and will incorporate into thrombi. Higher thrombus-to-blood activity ratios are obtained with 99mTc-fibrinogen than with radioidinated fibrinogen when both agents are injected into dogs 4 hr after induction of femoral vein thrombosis. Clearly delineated images of the thrombi are obtained, beginning about 2.5 hr after injection. Thus, 99mTc-fibrinogen may be of clinical use as a thrombus-imaging agent in patients under-going active thrombosis, especially in regions of high blood pool.
Letter: Preparation of 99mTc-fibrinogen.
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Effect of iodination level on the properties of radioiodinated fibrinogen.
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Radioiodinated soluble canine fibrin. Preparation and evaluation as a thrombus localizing agent in the dog.
To develop a thrombus localizing tracer which has characteristics superior to labeled fibrinogen for external detection, we evaluated radioiodinated soluble fibrin. Labeled soluble fibrin was prepared by clotting and dissolving radioiodinated (131I) canine fibrinogen under specified conditions. Biological clearance studies revealed rapid clearance of the labeled soluble fibrin from the blood with a half-life of 5 hours. The accumulation of labeled soluble fibrin and fibrinogen in induced venous thrombi, coronary artery thrombi, and the myocardium was compared in dogs. In venous thrombi, soluble fibrin and fibrinogen exhibited maximum thrombus-blood ratios when they were injected 4 hours after thrombus induction; the thrombus-blood ratio was greater for soluble fibrin than it was for fibrinogen when these agents were injected 4, 8, or 24 hours after thrombosis induction. In induced coronary artery thrombi, soluble fibrin and fibrinogen accumulated to the same extent. Since the blood clearance of soluble fibrin is faster than that of fibrinogen, a higher thrombus-blood ratio was obtained with soluble fibrin in coronary artery thrombi. The thrombus-infarcted myocardium, thrombus-normal myocardium, and infarcted myocardium-normal myocardium ratios obtained with soluble fibrin were slightly higher than those obtained with fibrinogen. Thus, soluble fibrin offers some advantages when it is compared with fibrinogen as a thrombus detecting agent.
Fibrinogen uptake by thrombi: effect of thrombus age.
The uptake of radiolabeled fibrinogen in canine thrombi was determined at varying times after thrombus induction by electric current. The greatest thrombus/blood ratio was achieved when fibrinogen was administered 4 hr after thrombus induction but definite thrombus fibrinogen uptake was still observed when the tracer was administered up to 72 hr after thrombus induction. There was continued fibrinogen accumulation despite a decrease in weight of older thrombi suggesting that net thrombus propagation is not necessary for labeled fibrinogen uptake. Our results suggest that the fibrinogen uptake test may be useful for the diagnosis of deep vein thrombosis for several days after the onset of thrombosis.
Highly iodinated fibrinogen: a new thrombus-localizing agent.
We have examined radioiodinated fibrinogen prepared at high levels of iodination as an agent for improved in vivo thrombus detection. Fibrinogen containing 25, 50, and 100 atoms of iodine per molecule is prepared by an electrolytic procedure and is compared with conventional radiolabeled fibrinogen (less than 0.5 iodine atom per molecule) prepared by the iodine monochloride method. The level of iodination has little effect on the isotopic clottability of the product, but its degree of aggregation and its rate of blood clearance in experimental animals is strongly dependent on iodination level. Isotopic thrombus: blood ratios obtained in recently induced thrombi with the 25 atom per molecule preparation average about 50:1, twice as high as the ratios obtained with conventionally labeled fibrinogen.
Determination of disulphide bridges in PG-2, an antimicrobial peptide from porcine leukocytes.
We determined the cysteine connectivity of protegrin PG-2, a leukocyte-derived antimicrobial peptide, by performing sequential enzyme digestions with chymotrypsin and thermolysin, and monitoring each digest by direct liquid chromatography-electrospray mass spectrometric analysis. This approach resolved the disulphide pairing pattern unambiguously with only picomolar amounts of PG-2. The inferred cysteine connectivity was confirmed by traditional amino acid composition analyses using nanomolar amounts of the protegrin. The results suggest that protegrins will assume a tachyplesin-like, disulphide-stabilized anti-parallel beta-sheet configuration in solution.
123I-labeled soluble fibrin: preparation and comparison with other thrombus imaging agents.
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Plasma beta-thromboglobulin, platelet factor 4, fibrinopeptide A, and other hemostatic functions during improved, short-term glycemic control in diabetes mellitus.
To determine the effect of improved, short-term glycemic control on various functions of hemostasis in insulin-dependent diabetes, we measured changes in plasma fibrinogen, fibrinopeptide A (FPA), functional antithrombin III (AT-III), factor VIII:ristocetin cofactor ( VIIIRCoF ), beta-thromboglobulin (BTG), platelet factor 4 (PF4), and platelet aggregation responses to ADP and collagen in 12 patients with low or undetectable stimulated (postprandial) serum C-peptide levels during 4-8 wk (median, 6 wk) of treatment with constant subcutaneous insulin infusion. Mean plasma fibrinogen, FPA, AT-III, VIIIRCoF , and BTG at baseline were elevated compared with normal. Three patients had heightened platelet responses to ADP that did not correlate to other indicators of a hypercoagulable state; the affected patients, in fact, had significantly lower plasma BTG (25.5 +/- 5.3 [SEM] versus 44.6 +/- 4.6 ng/ml, P less than 0.05) and FPA (1.1 +/- 0.1 versus 2.5 +/- 0.5 ng/ml, P less than 0.05) than the remaining patients. Patients with clinically evident vascular disease had higher baseline plasma BTG and FPA than those without vascular disease (44.6 +/- 5.4 versus 30.2 +/- 4.6, and 2.6 +/- 0.6 versus 1.3 +/- 0.2 ng/ml, P less than 0.05, respectively). During treatment, all patients had declining blood glucose (200 +/- 18 to 102 +/- 5 mg/dl, P less than 0.001) and HbA1 (11.8 +/- 0.6 to 10.2 +/- 0.4%, P less than 0.005). No statistically significant changes in hemostatic functions were noted. During treatment, one patient had an acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)
[Defensins and antibiotic peptides related to them in the evolution of animal protective systems].
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