bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement Of Prostaglandins That Activate Platelet Adenylate Cyclase In Rabbit Arterial Blood; Studies On PGI2 And 6-KETO-PGE1
Authors: Haslam R J , McClenaghan M D 
Published: July 2018

The increases in platelet cyclic [3H]AMP on addition of washed rabbit platelets containing 3H-labelled adenine nucleotides to fresh arterial blood samples mixed with 1 mM 3-isobuty1-1-methyl xanthine permitted assay of any activators of adenylate cyclase present. Blood PGI2 was calculated from the difference between the increases in cyclic [3H]AMP over 30 s in the presence and absence of antibody that bound PGI2 and the effects of PGI2 standards on cyclic [3H]AMP formation in preincubated blood. The PGI2 found in rabbit blood assayed within 2.5 min of arterial puncture (0.05 ± 0.01 pmol/ml in 10 males and 0.07 ± 0.02 pmol/ml in 8 females (means ± S.E.M.)) was far less than that needed to inhibit platelet function (>1 pmol/ml). The antibody used also bound 6-keto-PGE1, a metabolite of PGI2 that was one fifth as effective, both as an activator of rabbit platelet adenylate cyclase and as an inhibitor of platelet aggregation. PGI2 and 6-keto-PGE-1 were distinguished by their halflives in citrated blood at 37°C (10 and 44 min, respectively). Fresh arterial blood contained no assayable activity after incubation for 30 min, confirming that the material measured was PGI2.After an intravenous bolus injection of 1 nmol PGI2/kg, arterial PGI2 averaged 1.7 pmol/ml after 2 min (i.e. 90% had been removed) and returned to preinjection levels after 10 min. 6-Keto-PGE1, injected intravenously at 5nmol/kg, was cleared at a similar rate. After a bolus injection of 5 μg angiotensin II/kg, the PGI2-like material in arterial blood amounted to 7 pmol/ml after 2 min, but declined rapidly to control levels within 10-30 min. This PGI2-like material had the same half-life in vitro as authentic PGI2.The results show that though physiologically significant PGI2 does not normally circulate in rabbits, angiotensin II can raise blood PGI2 to inhibitory levels. Formation of 6-keto-PGE1 is unlikely to contribute to the effects of PGI2 on platelets in rabbits
A Life-Long And Ultimately Fatal Bleeding Syndrome Due To Grossly Increased Levels Of Plasma Plasminogen Activator
Authors: Bennett B , Booth N A , Cumming A M , Cook I A , Dawson A A , Knox J 
Published: July 2018

Episodes of haemorrhage due to increased fibrinolytic activity alone are uncommon and lifelong bleeding disorders due to excessive fibrinolysis are very rare. We report on a 46 year old male with a lifelong history of abnormal haemorrhage, usually occurring a day or two after minor trauma, surgery or dental extraction; no benefit had been derived from transfusion of fresh frozen plasma. There was no family history of bleeding but his father and grandfather had died at an early age of myocardial infarction and the patient had an abnormal lipid profile. No deficiency of any known clotting factor was present apart from a mild reduction of plasma fibrinogen (200mg/100ml). Platelet function was normal. The whole blood clot lysis time was consistently very rapid at 6-8 hours over a 2 year period of study. Levels of plasminogen, α1-antiplasmin, α2-antitrypsin, α2-macroglobulin, antithrombin III and CIs - inhibitor were normal but levels of plasminogen activator were grossly increased as were those of fibrin/fibrinogen related antigens (FRA).He ultimately developed a massive spontaneous intracerebral haemorrhage which proved fatal after an illness lasting 7 days, during which administration of tranexamic acid abolished evidence of overactive fibrinolysis and resulted in a rapid rise of plasma fibrinogen to 700mg/100ml and a fall in FRA levels. Autopsy showed generalised severe atheroma. Thus the presence of grossly increased levels of fibrinolytic activity over many years did not prevent the development of atheroma in this patient in the presence of disordered lipoprotein metabolism though it may have contributed to the absence of thrombotic occlusions adjacent to atheromatous plaques.
Primary Structure Of α2-Macroglobulin
Authors: Sottrup-Jensen L , Stepanik T M , Lønblad P , Rider D M , Petersen T E , Magnusson S 
Published: July 2018

The α2M tetramer of Mr 725,000 consists of four apparently identical single polypeptide chain monomers of Mr 180,000, corresponding to about 1450 amino acid residues. At the present stage of our sequence determination 1383 residues can be accounted for in three segments of continuous sequence namely the N-terminal (residues 1-440); the “middle” of 298; the C-terminal of approx. 645 residues. The eight oligosaccharide prosthetic groups are glucosamine-based and attached to Asn-residues, five in the N- terminal, three in the C-terminal segment. 25 CNBr-frag- ments have been found, 22-Met-residues have been overlapped. 23 Cys-sequences have been determined so far and ten -S-S- bridges identified. The Cys-residue (approx, no. 472 from the C-terminal in each chain) of the sequence is thiol-ester linked to the γ-carboxyl of the Glx-residue in native α2M which has not been reacted with proteinase or “inactivated” with methylamine or by heat inactivation.Neither extensive internal sequence homology, nor homology with other proteinase inhibitors of known primary structure has yet been observed.
Inhibition Of Human Factor Xa By Various Plasma Protease Inhibitors
Authors: Scully M F , Ellis V , MacGregor I R , Kakkar V V 
Published: July 2018

The second order rate constants for the interaction of human factor Xa with antithrombin III (in the absence of heparin) α1 antitrypsin and α2 macroglobulin have been determined at pH 7.4 (50mM Tris HCl, 0.1M NaCl) in the presence of 3mM CaCl2. Factor Xa (free of activation peptide) and α1 antitrypsin were purified from outdated human plasma. Pure human preparations of antithrombin III and α2 macroglobulin were obtained elsewhere. The rate of inhibition was measured by determining the residual factor Xa activity at time intervals using S2337. In the case of the inhibition by α2 macroglobulin, measurement was made of bound factor Xa by carrying out the assay in the presence of soybean trypsin inhibitor, The rates were determined at molar concentrations of inhibitor to factor Xa of 1:1, 2:1, 4:1, and 8:1 and were concentration dependent indicating second order kinetcis. Suitable plots according to the full second order rate equation yielded straight lines from which the rates constants were calculated.Calculated values for the inhibition of factor Xa by antithrombin III, α1 antitrypsin and α2 macroglobulin were 5.80×104 M-1 min-1, 1.36×104 M-1 min-1 and 4.00×104 M-1 min-1 respectively. The potential effectiveness of the inhibition for the inactivation of factor Xa in plasma can be calculated from these rate constants and the plasma levels of the inhibitors. Assuming plasma concentrations of the inhibitors to be 4.46μM, 42.4μM and 3.11μM respectively, the relative order of effectiveness under plasma conditions is α1 antitrypsin > antithrombin III > α2 macroglobulin in the proportions 4.64 : 2.08 : 1.00. These results are in contrast to the calculated effectiveness in plasma of these inhibitors against thrombin (of which antithrombin III is the most effective inhibitor). Cephalin was found to inhibit the interaction between factor Xa (2.8×104 M-1 min-1 at 100 μg/ml) and antithrombin III but not between factor Xa and α1 antitrypsin.
An Assessment Of Subcutaneous Ancrod In Prevention Of Deep Vein Thrombosis After Surgery For Hip Replacement
Authors: Belch J , Meek D , Lowe G , Drummond M , Campbell A , Forbes C , Prentice C 
Published: July 2018

There is a high incidence of deep vein thrombosis (DVT) and pulmonary embolism (PTE) amongst patients undergoing surgery for hip replacement. We have assessed the use of ancrod (Arvin), a de- fibrinating enzyme in the prophylaxis of DVT.In a randomised double-blind controlled trial 35 patients received daily subcutaneous injections of ancrod after operation for hip replacement and 38 patients received saline injections. DVT was detected by bilateral ascending venography (68 patients) or post-mortem (1 patient) 7-19 days after surgery. The frequency of major femoral DVT (> 5 cm long) was significantly reduced from 18 thrombi in the limbs of the placebo group to 5 in the ancrod group ( p<0.05). Major bilateral femoral DVT were similarly reduced from 7 to 1 patients by treatment with ancrod.The overall frequency of all thrombi, including calf DVT, was however not significantly different between the groups. 5 patients had evidence of PTE (3 placebo, 2 ancrod). 6 patients within the ancrod group had evidence of increased wound bleeding, compared with one placebo patient, but in only one patient was this considered severe enough to require cessation of ancrod injections. As the majority of PTE perhaps arise from large femoral thrombi it would seem that ancrod prophylaxis, by reducing thrombus size, could aid the reduction of PTE in this group of patients.
Randomized Clinical Trial Of Titrated Dose Subcutaneous Heparin Versus Warfarin In The Long-Term Treatment Of Patients With Venous Thrombosis
Authors: Hull R , Delmore T , Carter C , Hirsh J , Genton E , Turpie A , Sackett D , Gent M 
Published: July 2018

We have reported previously that low-dose subcutaneous (sc) heparin is less effective than adjusted dose warfarin sodium in the long-term treatment of venous thrombosis as 9 of 35 patients (26%) receiving low dose sc heparin developed acute recurrent venous thromboembolism compared with none of 33 patients receiving warfarin (p=0.001).Seven patients on warfarin suffered bleeding compared with none on low-dose sc heparin (p < 0.005). Using an identical study design, 101 patients with venographically confirmed acute deep vein thrombosis have entered a second trial reported here, comparing higher doses of sc heparin 12 hourly, titrated at the onset (by adjusting the mid interval PTT to 1½ to 2 times control), compared with adjusted dose warfarin (PT 1½ to 2 times control). All patients were treated with full doses of heparin for 14 days and then randomized to either treatment group for a 12 week course. The patients were followed in a special clinic and routinely screened with leg scanning and impedance plethysmography at 3 week intervals and on an emergency basis if they developed recurrent symptoms.During long-term treatment no patient on warfarin or titrated sc heparin developed recurrent venous thromboembolism. On follow-up, after discontinuation of long-term therapy, 4 patients randomized to warfarin and 4 patients randomized to titrated sc heparin developed recurrent deep vein thrombosis confirmed by objective testing. One of 51 patients on titrated sc heparin suffered bleeding compared with 9 of 50 patients on warfarin (p < 0.02).These results suggest that titrated sc heparin is as effective as warfarin for preventing recurrent venous thromboembolism and its use is associated with less bleeding than warfarin.
Acquired Platelet Storage Pool Disease In Chronic Autoimmune Thrombocytopenia (ITP) And Marrow Dyspoiesis
Authors: Malpass T W , Savage B , Slichter S , Harker L A 
Published: July 2018

The mechanism underlying platelet dysfunction in patients with chronic ITP or marrow dyspoiesis has been characterized with respect to template bleeding times, platelet nucleotides and a granule contents. Ten patients with modest thrombocytopenia (93,000 plat/ul ± 53,000) due to chronic ITP (4), “preleukemia” (4), primary myelofibrosis (I), and polycythemia vera (I) were selected for study on the basis of discrepantly prolonged bleeding times in excess of that predicted by the platelet count, i.e. BT = 30.5 -platelet count/3850. Using high pressure liquid chromotography, adenosine diphosphate (ADP) and adenosine triphosphate (ATP) were measured in both whole platelet extracts and the supernatant of thrombin stimulated platelets. From these measurements it was possible to determine the relative distribution of ATP and ADP in the cytoplasmic and dense granule compartments. The α granule protein, platelet factor four (PF4), was determined by RIA.Whereas dense granule ADP was markedly reduced (mean 0.92 ± 0.58 u moles/1011 platelets compared with 2.41 ± 0.20 in 20 normal subjects; p < 0.01), platelet cytoplasmic ATP and ADP were not decreased 3.49 ± 0.45 and 0.40 ± 0.27 u moles/1011 platelets compared with 2.73 ± 0.27 and 0.3l ± 0.15 in normals respectively). The severity of the platelet dysfunction (difference in the observed bleeding times from predicted) varied directly with the decrease in dense granule ADP (R2 = 0.88). Only three patients (all with dyspoiesis) also demonstrated an associated α gronule abnormality as shown by partial depletion of the platelet content of PF4. Platelet survival studies done simultaneously with 51Cr and 14C-serotonin showed discrepantly shortened 14C-serotonin disappearance in 3 patients (I ITP, 2 dyspoiesis) suggesting preferential dense granule losses from circulating platelets. Possible mechanisms of platelet dense granule ADP depletion may include activation and release or leak of dense granule contents or defective platelet development in the marrow. We conclude that platelet dysfunction may occur in some patients with chronic ITP and hematodyspoiesis due to acquired dense granule storage pool disease.
Correlations Between Platelet Consumption And The Surface Chemistry Of Neutral Polymers In Baboons
Authors: Hanson S R , Ratner B D , Haffman A S , Harker L A 
Published: July 2018

The rate of destruction of autologous 51Cr-labeled blood platelets has been measured in baboons having femoral arteriovenous shunts composed of various test materials. Platelet survival was normal in baboons with chronic Teflon-Silastic shunts alone demonstrating that the surgical variables had no detectable effect. Platelet survival data obtained when other materials were studied were analyzed by computer modeling to estimate both the rate of shunt-associated platelet destruction and the rate of platelet removal by ordinary senescent mechanisms. Rates of shunt associated platelet destruction, normalized with respect to shunt surface area (plats/cm2 -day), were used to assess material thrombogenicity. Polymers studied included poly(ethyl methacrylate) (EMA), poly(hydroxyethyl methacrylate) (HEMA) and two intermediate copolymers (HEMA/EMA: 1/1, 1/3) radiation grafted onto two substrates (silastic and polyethylene). Og both substrates rates of platelet consumption (range:	5-20 × 108 plats/cm2 -day) correlated with:	I) HEMA/EMA monomer ratios; 2) graft polymer water absorption measurements; and 3) surface ratios of carbon to oxygen atoms and of various functional groups as determined from electron spectroscopy for chemical analysis (ESCA). With ten commercial polyurethane materials rates of platelet consumption (range: 2-23 × 108 plats/cm2 -day) correlated inversely with the percentage of surface carbon atoms forming hydrocarbon bonds, and directly with the surface content of ether-type linkages (which will be related to polyether “soft” segments) as determined from ESCA.These observations in primates indicate that the thrombo- genecity of prosthetic materials is strongly influenced by their surface physicochemical properties.
The Influence Of Materials And Platelet Inhibition On The Thrombogenicity Of Arterial Grafts In Man
Authors: McCollum C N , Norcott H C , Hawker R J , Goldman M , Drolc Z , Snape E 
Published: July 2018

Prosthetic arterial grafts often thrombose when used to bypass diseased small arteries due to the deposition of laminated platelet thrombus. The rate of lll-Indium labelled platelet accumulation on autogenous vein, polytetra- fluoroethylene (PTFE, Gore-Tex) and double velour Dacron (Microvel) has been investigated in patients and the influence of aspirin and dipyridamole (ASA/DPM) evaluated.Two days before surgery 40 patients undergoing femoro-popliteal bypass were started randomly and double blind, on either ASA 300 mgm + DPM 75 mgm tds or placebo. One week postoperatively autologous 111-Indium labelled platelets were injected and isotope emissions over the graft and contralateral leg counted for 7 days. Graft thrombogenicity was calculated as the daily rise in the ratio of counts, graft/contralateral thigh.Three placebo and one ASA/DPM prosthetic grafts occluded prior to study. Thrombogenicity (mean ± SEM) was greatest in the Dacron grafts at 0.22 ± 0.03 on placebo (n=7) and 0.16 ± 0.03 on ASA/DPM (n=5) (p < 0.05). The effect of therapy however, was most striking in reducing thrombogenicity of PTFE grafts from 0.17 ± 0.03 (n=4) to 0.06 ± 0.01 (n=7) (p < 0.02). The thrombogenicity of 0.03 ± 0.005 was so low in the 13 vein grafts that the effect of therapy could not be determined.The 111-Indium platelet technique described may be used to quantitate in vivo platelet deposition. In man the combination of ASA/DPM reduced the rate of thrombus formation on prosthetic materials. PTFE grafts with ASA/DPM therapy most nearly approach the low thrombogenicity of vein.
Role Of Verapamil (Calcium Blocker) In The Reduction Of Platelet Deposition In Gore-Tex Grafts In Dogs
Authors: Fuster V , Dewanjee M K , Murphy k , Vlietstra R E , Didisheim P , Kaye M P 
Published: July 2018

Platelet calcium appears to be essential in platelet activation. Accordingly, Verapamil (a channel calcium blocker) was tested “in vivo” as a possible platelet inhibitor agent. Fifteen dogs underwent bilateral femoral artery grafting with one polytetrafluoroethylene (Gore-Tex) and one autologous vein graft. Peroperatively, five dogs were infused continuously with Verapamil (6 μgs/kg/min) and 9 dogs were left untreated and the arterial prostheses were surgically implanted. Using autologous Indium-111-labeled platelets injected 24 hours prior to surgery as a platelet marker, grafts were removed 1 hour following resumption of blood flow. Radioactivity per unit weight of Gore-Tex, vein and blood were determined with a gamma counter and the relative radioactivity with respect to the internal reference standard of blood is tabulated belowVerapamil-treated dogs showed a significant reduction in the “in vivo” platelet deposition on Gore-Tex and autologous venous grafts. Preliminary data indicates that “in vitro” platelet aggregation with soluble calf skin collagen (515 μg/ml) and ADP (2-100 μm) is not different between control and drug-treated dogs.Calcium channel blockers may be promising “in vivo” platelet inhibitor agents; in addition, they may provide further understanding of the different processes involved in “in vivo” and “in vitro” platelet activation.
Evaluation Of Pharmacologic Inhibitors Of Platelet Function In Baboons
Authors: Hanson S R , Harker L A 
Published: July 2018

The ability of aspirin (ASA), dipyridamole (DIP), sulfinpyrazone (SP) and combinations of these agents to prevent arteriovenous cannula thromboembolism In baboons .has been assessed by measuring the destruction of autologous 51Cr-platelets. In 24 studies with untreated baboons (10-12 kg), thrombogenic polyurethane femoral A-V cannulap (Biomer, 50 cm, 4 mm i.d.) consumed 22.5 ± 4.5 × 108 plats/cm2 -day. In animals with identical shunts, the efficacy of various antithrombotic treatment regimens was determined by measuring the percent reduction in platelet consumption (PC) compared to untreated control values. All drugs were given to at least four animals by oral administration twice daily.ASA, 3-100 mg/kg/day, did not significantly reduce PC (p >0.2). SP In doses of 10, 50 and 100 mg/kg/day reduced PC by 7, 48, and 97% respectively. DIP, 1, 2.5, 5, 10 mg/kg/day, reduced PC by 14, 34, 5l,and 99% and was significantly more effective than SP (p <10-5). ASA (10, 15, 20 mg/kg/day) given with DIP (2.5 mg/kg/day) reduced PC by 47, 67, and 94% demonstrating significant and dose dependent potentiation of DIP by ASA. ASA (10 mg/kg) potentiated DIP (2.5 mg/kg/day) less effectively when given only with the first dose of DIP, or when given twice daily but two hours after administration of DIP (p <0.01). In both cases PC was reduced about 67% (vs. 94% for simultaneous administration twice daily). DIP (2.5 mg/kg/day) plus SP (10, 20, 40 mg/kg/day) reduced PC by 50, 51, and 72% in an additive fashion without potentiation. Similarly SP (20 mg/kg/day) given with DIP (2.5 mg/kg/day) plus ASA (10 mg/kg/day) reduced PC by 65% In an additive manner.It is concluded that PC Is more effectively reduced by DIP than either SP or ASA. DIP Is potentiated by ASA but not SP. DIP and ASA should be administered simultaneously in multiple daily doses.
Characterization Of Cdna Clones Coding For The α And β Chains Of Bovine Fibrinogen
Authors: Chung D W , Rixon M W , MacGillivray R T A , Davie E W 
Published: July 2018

Radioactive cDNA was synthesized from a bovine liver mRNA preparation enriched for fibrinogen mRNA activity. This cDNA was used in a solution hybridization assay to screen a collection of recombinant plasmids carrying bovine cDNA inserts. A number of plasmids containing cDNAs for fibrinogen were identified.The nucleotide sequence of the insert of one plasmid, designated pBIβ1, has been determined. It contains 1372 base pairs and codes for the C-terminal 424 amino acids of the β chain of bovine fibrinogen. This and other previous-ly reported partial sequences enabled the construction of the complete amino acid sequence of the bovine β chain. Comparison of this sequence with that of the human β chain shows a high degree of homology. The positions of all the cystine and tryptophan residues are identical.The nucleotide sequence of the insert of another plasmid, designated pBIα1, has also been determined. This plasmid contains 965 base pairs and codes for the C-terminal 203 amino acids of the bovine a chain. This region shows only 46% homology with the corresponding region in the human α chain. A hypervariable region, consisting of 53 amino acids, is present in the bovine a chain. This region shows little homology with the corresponding region in the human α chain. Furthermore, it is 26 amino acids shorter than the corresponding region in the human a chain.The cDNAs to the bovine fibrinogen chains will provide good probes for the study of human fibrinogen and the organization and structure of its genomic DNA.
Fibrinogen Lille : Aα7ASP ⤒ ASN
Authors: Morris S , Denninger M H , Finlayson J S , Menache D 
Published: July 2018

Previous studies on fibrinogen Lille indicated a structural defect in the NH2-terminal region involving the Aα chain. The rate and extent of fibrinopeptide A release were greatly diminished. This was further evidenced by the NH2-terminal analysis of fibrin which showed alanine in addition to tyrosine and glycine and by the finding that fibrinopeptide A was being maintained on fragment E for a prolonged period of plasmic hydrolysis.To further elucidate the abnormal structure, fibrinogen Lille was isolated by glycine precipitation, reduced, carboxymethylated and the chains separated by ion exchange chromatography. Approximately 50 nanomoles of either normal or Lille reduced and carboxymethylated Aa chains were subjected to automated sequence analysis using a single cleavage program in 0.1 M Quadrol. PTH amino acids were identified by a combination of high performance liquid chromatography and mass spectroscopy. The normal Aα chain was sequenced up to position 10 and the expected fibrinopeptide A sequence was obtained. Aa Lille chain was analysed up to position 20 on one sample and up to position 10 on another sample. A single sequence was obtained in both experiments; it was identical to the normal Aa sequence with the exception of position 7, which was identified as a mixture of aspartic acid and asparagine. These results, consistent with a single base change, suggest two distinct populations of fibrinogen and a substitution in the highly conserved region of fibrinopeptide.