Biomedical subjects

W Jeske

Publications and source records attributed to W Jeske.

At least 19 recordsLinked to original sources

PubMed1995

Anticoagulant and antithrombotic actions of a semisynthetic beta-1,3-glucan sulfate.

Sulfation of the natural polysaccharide curdlan results in anticoagulantly active beta-1,3-glucan sulfates whose activity depends on various structural parameters. In this study the anticoagulant and antithrombotic effects of one of these beta-1,3-glucan sulfates (GS) were compared with those of a porcine mucosal heparin. GS produced a concentration dependent anticoagulant effect in all the global coagulation assays with the exception of the anti-Xa assay. The best activity was found in the APTT and the thrombin time assays indicating that protease generation and the direct inhibition of thrombin may be sites of actions of this agent. Whereas the anticoagulant activity of GS was approximately 5 fold lower compared to heparin, a 32 fold higher concentration (ED50 = 550 micrograms/kg) was needed for an antithrombotic effect similar to heparin (ED50 = 17.2 micrograms/kg) in a rabbit model of stasis thrombosis. In contrast to this, when a rat model of clamping induced jugular vein occlusion was used to produce vascular obstruction, GS produced similar antithrombotic actions to heparin. At a 250 micrograms/kg dosage, both agents doubled the number of clampings required for complete vascular obstruction. Since the mechanical injury to the blood vessel is the primary determinant of the thrombogenic response, GS may inhibit some of the pathophysiologic mechanisms responsible for the occlusion of the blood vessel. The current study also points to the fact that the global anticoagulant effects may not reflect the antithrombotic potential of newer sulfated carbohydrate derived drugs.

Animals↗

PubMed1995

TFPI antigen levels in normal human volunteers after intravenous and subcutaneous administration of unfractionated heparin and a low molecular weight heparin.

Tissue factor pathway inhibitor (TFPI) is an important mediator of the in vivo anticoagulant/antithrombotic properties of unfractionated heparin (UFH) and low molecular weight heparin (LMWH). The vascular pool of TFPI is released into the circulation after intravenous and subcutaneous administration of both UFH and LMWH. We have administered LMWH (Ardeparin) and UFH to normal human volunteers in a dose dependent manner. Our results demonstrate that the TFPI antigen levels increase upon the intravenous and subcutaneous administration of UFH and Ardeparin. Because of the better bioavailability of LMWH by the subcutaneous route at equigravimetric dosages, Ardeparin released more TFPI than UFH. However, when given intravenously an identical release of TFPI from the vasculature has been observed. The plasma concentration of TFPI was increased 0.5-2 fold when UFH or Ardeparin was administered subcutaneously and was 3 fold higher when administered intravenously. This profound increase in TFPI antigen levels was dependent on the dosage of Ardeparin administered. This release in TFPI correlates with prolongation of the Heptest clotting assay. However, it appears from this study that TFPI release precedes the elevation of the Heptest clotting time.

Adult↗

PubMed1995

Molecular profiling and weight determination of heparins and depolymerized heparins.

The recently proposed calibrant LHN-1 (lot F537; henceforth designated F537), for the molecular weight (MW) determination by high-performance size-exclusion chromatography of heparins, is shown here to have a range too narrow to allow for the accurate MW determination of all low molecular weight heparins (LMWHs). We have recently demonstrated, by this same methodology, that a chemically degraded benzyl ester of unfractionated heparin, heparin mass calibrator (HMC), is a better calibrant. Weight-average MW, number-average MW, peak MW, and dispersity values were calculated with F537, HMC, and by a reference narrow-range-calibration method for various LMWHs and unfractionated heparins. Values for these parameters determined with HMC were not significantly different from those determined by the reference method until the MW of the substance exceeded 15.0 kDa. In contrast, the MW profile obtained with F537 was appreciably different from that obtained by the reference method for samples with MWs > 7.5 kDa. The range exhibited by HMC should allow this calibrant to be used for both LMWHs and unfractionated heparins.

Heparin↗

PubMed1995

A comparative study on the mechanism of the anticoagulant action of mollusc and mammalian heparins.

The anticlotting activities on some steps of the coagulation cascade of mollusc and mammalian heparins were studied. AT III-high affinity heparin is a more potent inhibitor than unfractionated heparin and mollusc heparin in the intrinsic and extrinsic pathways of thrombin and factor Xa generation. Mollusan heparin has about the same activity as the AT III high affinity-heparin on the inhibition of factor Xa and thrombin in the presence of antithrombin III and four times more inhibitory activity than unfractionated heparin on the heparin cofactor II mediated inhibition of thrombin.

Animals↗

PubMed1995

Antithrombin III affinity dependence on the anticoagulant, antiprotease, and tissue factor pathway inhibitor actions of heparins.

To investigate AT-III affinity dependence on heparin's actions, heparin (UH) was fractionated on an AT-III-Sepharose column into a high (HAH) and a low affinity (LAH) fraction. Molecular profiling revealed a molecular weight of 11.8 kDa for (UH), 12.6 kDa for HAH, and 10.6 kDa for LAH. The USP anticoagulant potencies were found to be: UH = 160 U/mg, HAH = 198 U/mg, and LAH = 42 U/mg. The anticoagulant effects of each of these fractions were proportionate to the USP potencies. However, protease generation inhibitory activities did not follow the same order. All fractions were also tested for their interactions with tissue factor pathway inhibitor (TFPI). No significant differences were noted on the anti-Xa effects of TFPI with these fractions. Administration of each fraction to primates resulted in equivalent release of TFPI. In a model of jugular vein clamping induced venous occlusion, all agents produced a dose-dependent antithrombotic action. HAH produced a 60 to 70% stronger antithrombotic effect than LAH or UH. Simultaneous administration of TFPI markedly augmented the antithrombotic actions of both UFH and LAH. The effect of TFPI on the antithrombotic activity of HAH was weaker than that on LAH. These observations suggest that AT-III affinity is not the sole determinant of the antithrombotic actions of heparin. The endogenous release of TFPI may contribute to the antithrombotic actions of heparin and related glycosaminoglycans. Furthermore, TFPI is capable of AT-III independent amplification of the antithrombotic actions of both UH and LAH, suggesting a crucial role of this polyvalent inhibitor in the control of thrombogenesis.

Animals↗

PubMed1995

Pharmacologic profile of a low-molecular-weight heparin depolymerized by gamma-irradiation.

Low molecular weight heparins (LMWHs) are considered to be the agent of choice for the prophylaxis of DVT in medical and surgical patients. Conventionally, these agents have been produced by fractionation of or by chemical or enzymatic depolymerization of native heparin. The fractionated heparin retains many of its biological properties such as AT III affinity and sulfate content gamma-irradiation (60Co) has been used to depolymerize GAGs (De Ambrosi et al. In: biomedical and Biotechnological Advances in Industrial Polysaccharides, pp. 45-53). This procedures has now been used for the preparation of LMWH derivatives of varying molecular weight. The current studies examine the biochemical and pharmacologic profile of one such gamma-irradiated depolymerized heparin. In standard clotting and amidolytic antiprotease assays (PT, APTT, AXa, Alla), gamma-irradiated depolymerized heparin produced equal or stronger activity when compared to a LMWH produced by nitrous acid depolymerization and retained the ability to active AT III and HCHII. Initial results indicate that LMWHs produced by gamma-irradiation exhibit comparable antithrombotic actions to those produced by chemical depolymerization when measured in animal models of thrombosis. gamma-Irradiation may be a useful method for the production of LMWHs.

Animals↗

PubMed1995

Pharmacologic validation of the clinical effects of an optimized low-molecular-weight heparin-reviparin.

Reviparin is a low-molecular-weight heparin (LMWH) prepared by controlled nitrous acid digestion of porcine mucosal heparin. The trade name designation for this agent is Clivarin. This agent has been released in Germany and France for the prophylaxis of deep venous thrombosis (DVT) in surgical patients. This agent is developed utilizing optimized procedures and exhibits a uniform, narrow-molecular-weight distribution in comparison to the other commercially available LMWHs. The specific activity in the anticoagulant assays is approximated to be 32 U/mg whereas the specific activity in terms of anti-Xa units is designated 120 aXa U/mg. Reviparin is capable of producing a dose- and time-dependent antithrombotic effect in animal models of thrombosis. While the ex vivo effects are initially presented at antithrombotically active dosages, this agent has been found to produce antithrombotic effects without any detectable ex vivo actions. This agent is also known to release tissue factor pathway inhibitor (TFPI) after both intravenous (IV) and subcutaneous (SC) administration. Repeated administration of Reviparin produces progressively stronger antithrombotic effects. Similarly, the bleeding as measured by rabbit ear blood loss is also progressively increased. However, the ratio between the dosage producing these effects is quite large. The current studies are designed to provide additional data on the molecular profile using new calibration methods and additional results on the pharmacologic studies in a dose-dependent manner. In particular, the release of TFPI following IV and SC administration in a primate model is described. The effect of repeated administration mimicking the post-surgical prophylaxis of DVT is also reported in terms of any augmentation of the antithrombotic or hemorrhagic effects of these agents.

Animals↗

PubMed1995

Effect of repeated Aprosulate and Enoxaparin administration on tissue factor pathway inhibitor antigen levels.

Tissue factor pathway inhibitor (TFPI) is a naturally occurring, Kunitz-type serine protease inhibitor whose anticoagulant activity is due to an inhibition of the extrinsic coagulation pathway. Heparin injection has previously been shown to increase the plasma levels of TFPI. In this study, plasma samples were obtained from a multiple dose phase I tolerance study with a synthetic analogue of heparin, namely Aprosulate (PALLAS). Volunteers were randomized into four treatment groups: (A) 35 mg Aprosulate b.i.d. s.c.; (B) 70 mg Aprosulate b.i.d. s.c.; (C) 70 mg Aprosulate o.d. + placebo o.d. s.c.; (D) 40 mg of a low molecular weight heparin, Enoxaparin o.d. + placebo o.d. s.c. All treatments were for 7 days, with blood samples taken periodically over this time period. TFPI antigen levels were determined using Imubind TFPI ELISA kits (American Diagnostica, Greenwich, CT). TFPI antigen levels were observed to rapidly increase to levels two- to three-fold over baseline in all groups. Aprosulate caused a slightly larger increase in TFPI antigen levels than Enoxaparin, though this may be related to the doses chosen for this study. These data indicate that plasma concentrations of TFPI are increased following Aprosulate administration. TFPI may be important in mediating the antithrombotic activity of Aprosulate.

Analysis of Variance↗

PubMed1995

The role of tissue factor pathway inhibitor in the mediation of the antithrombotic actions of heparin and low-molecular-weight heparin.

It is widely accepted that antithrombin III (ATIII) mediated anti-Xa and anti-IIa effects are the sole determinant of the antithrombotic actions of unfractionated heparin (UFH) and low-molecular-weight heparins (LMWHs). However, there are several unexpected observations such as the greater than 100% bioavailability of subcutaneously administered LMWH as measured by a chromogenic based anti-Xa method. The authors have proposed that, besides ATIII mediated antiprotease actions, additional endogenous factors may be responsible for the observed therapeutic and prophylactic actions of heparins. With the identification of tissue factor pathway inhibitor (TFPI) some of the unexpected effects of heparins can now be clarified. To investigate the role of heparin-releasable TFPI on LMWHs the anti-Xa and TFPI antigen levels after prophylactic and therapeutic administration of UFH and LMWHs have been studied in defined clinical trials. Regardless of the dosage designation (mg/kg or units/kg) each LMWH followed a distinct TFPI release profile. Similarly, in the intravenous studies these LMWHs produced an instantaneous increase in the TFPI antigen level. The anti-Xa effects did not always follow the same pattern as the TFPI antigen levels. These data suggest that the anti-Xa potency of a given LMWH is not the sole determinant of the antithrombotic actions of heparin and LMWH. In addition to pharmacologic agents, the effect of sequential compression devices (SCD) on the release of TFPI was also studied. A two-fold increase in TFPI antigen levels was observed in normal volunteers undergoing long leg compression for 1 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Enoxaparin↗

PubMed1995

Measurement of functional and immunologic levels of tissue factor pathway inhibitor. Some methodologic considerations.

Tissue factor pathway inhibitor (TFPI) is a newly identified inhibitor of proteases generated during activation processes. Several functional methods based on a chromogenic substrate technique measuring residual tissue thromboplastin/FVIIa catalytic activity using excess factor X and a chromogenic substrate for FXa have been published. Recently, a sandwich ELISA method has become available. A modified functional method was compared with the ELISA based antigen method in several groups of normal individuals. The functional assay is sensitive to TFPI concentrations of 125-200 ng/ml based on a rTFPI standard. The immunologic method is sensitive from 0 to 400 ng/ml. A marked dichotomy was observed between the two methods. The ratio between TFPI antigen and functional levels varies widely in patient groups. This TFPI standard was supplemented with buffer and normal human plasma and functional TFPI was measured before and after heat treatment at 56 degrees C for 10 min. Heat treatment of plasma (buffer) after the addition of TFPI resulted in decreased functional TFPI compared with the addition of TFPI after the plasma (buffer) was heat treated. In contrast, the immunologic method does not require heat treatment. Addition of exogenous TFPI to plasmas obtained from normal and the above patient plasmas demonstrated that recovery of functional TFPI activity was plasma dependent. Plasma proteins markedly influenced functional and antigenic levels of TFPI. The TFPI standard added to human pooled plasma gave varying recoveries in the immunologic and functional assays. These results indicate that currently available methods may provide highly variable results on TFPI levels. Several matrix related effects should be taken into account for proper evaluation of TFPI.

Buffers↗

PubMed1995

Hyperinsulinaemia and decreased plasma levels of dehydroepiandrosterone sulfate in premenopausal women with coronary heart disease.

OBJECTIVES: The purpose of the study was to establish plasma levels of insulin, ovarian sex hormones and dehydroepiandrosterone sulfate (DHEA-S) and to evaluate their correlations with lipids in premenopausal women with angiographically demonstrated coronary stenosis. DESIGN: Differences in plasma levels of insulin, ovarian sex hormones, DHEA-S and lipids between groups were compared by analysis of variance. SETTING: From January 1993 until December 1993 patients were diagnosed in the Outpatient Clinic of the Department of Endocrinology Medical Centre for Postgraduate Education, Warsaw. SUBJECTS: Premenopausal women with normal oral glucose tolerance test (OGTT) results, with and without coronary stenosis were studied: 21 women after acute myocardial infarction with angiographically demonstrated coronary stenosis (women with CHD), and 14 women with chest pain, a positive exercise test without significant changes of coronary arteries on coronarography (women with normal coronarography, NC). The control group consisted of nine, healthy women with no risk factors for CHD. MAIN OUTCOME MEASURES: In premenopausal women with CHD, the decreased plasma level of DHEA-S and hyperinsulinaemia were anticipated. RESULTS: In women with CHD, the plasma levels of DHEA-S (926.5 +/- 83 ng mL-1) were significantly lower than those in women with NC (1375.7 +/- 181 ng mL-1) and in healthy controls (1984 +/- 127 ng mL-1), P < 0.02 and P < 0.001, respectively. The fasting insulin and insulin response to an OGTT in women with CHD and with NC was higher than in healthy subjects. A significant decrease of high-density lipoprotein (HDL) cholesterol, HDL-2 cholesterol and apolipoprotein A-I, and an increase of total cholesterol, low-density lipoprotein cholesterol C and apolipoprotein B levels in women with CHD compared to healthy controls were observed. A negative correlation between fasting insulin and the plasma levels of DHEA-S was established. CONCLUSION: In premenopausal women, hyperinsulinaemia and decreased DHEA-S levels may contribute to the development of coronary atherosclerosis.

Adult↗

PubMed1994

Inhibitory effects of TFPI variants on thrombin and factor Xa generation in fibrinogen-deficient human plasma.

Using a fast kinetic centrifugal analyzer, the inhibitory effects of glycosylated and unglycosylated full-length and truncated forms of TFPI on protease generation were studied in fibrinogen-deficient human plasma after extrinsic (EA) or intrinsic (IA) activation of coagulation. When the assay system was supplemented with increasing amounts of the TFPI variants the generation of both thrombin and factor Xa was inhibited in a concentration-dependent manner. Clear differences in the effectiveness of the TFPI variants were found. After EA, the unglycosylated full-length TFPI was most effective followed by the glycosylated full-length form. The C-terminal truncated TFPI showed the lowest inhibitory activity in this system. However, its efficiency increased several fold when coagulation was activated via the intrinsic pathway. Comparing the IC50 values after IA, the truncated TFPI was more effective than the unglycosylated full-length form and nearly as effective as the glycosylated full-length TFPI. After both EA and IA the thrombin generation inhibition by TFPI variants was more pronounced than the inhibition of factor Xa generation. The results show that chemical modifications of the TFPI structure can result in changes of TFPI's inhibitory properties to activated clotting factors leading to differences in protease generation inhibition.

Afibrinogenemia↗

PubMed1994

Inhibitory effects of TFPI on thrombin and factor Xa generation in vitro--modulatory action of glycosaminoglycans.

The effect of tissue factor pathway inhibitor (TFPI) on thrombin and factor Xa generation was studied in an in vitro system using a prothrombin complex concentrate. It was found that TFPI, via the direct inhibition of factor Xa and the tissue factor/factor VIIa complex, inhibited both the further generation of factor Xa and the generation of thrombin in a concentration-dependent manner. The generation of thrombin (IC50 255 ng/ml) was more pronounced than that of factor Xa (IC50 684 ng/ml). The inhibitory activity of TFPI was significantly enhanced when unfractionated heparin was present in the assay system at a concentration of 10 micrograms/ml which did not show any inhibitory effects on protease generation in the same system. Furthermore, the influence of TFPI at subthreshold concentrations (100 ng/ml and 200 ng/ml, resp.) on the inhibitory action of unfractionated heparin (UFH), a low molecular weight heparin (LMWH), heparan sulfate (HS) and the synthetic heparin pentasaccharide (PS) was investigated. Whereas in the concentration range used (0.3-40 micrograms/ml) these glycosaminoglycans did not inhibit thrombin and factor Xa generation, after supplementation of the system with TFPI a concentration-dependent inhibition of the generation of the proteases up to 40-50% was seen for UFH, LMWH and HS. TFPI did not increase the activity of PS.

Animals↗

PubMed1994

Antithrombotic agents stimulate the synthesis and modify the sulfation pattern of a heparan sulfate proteoglycan from endothelial cells.

Low molecular weight heparins, namely CY 216 and CY 222 (Sanofi/Choay); OP 622 and OP 386 (Opocrin); PK 10169 (Pharmuka); an oligosaccharide prepared from heparin by heparitinase II digestion; chemically sulfated glycosaminoglycans and polysaccharide namely Suleparoid (Syntex), Aprosulate (Luitpold-Werk); chemically modified glycosaminoglycans GAGPS and MPS (Luitpold-Werk) as well as unmodified heparin stimulate two to three fold the synthesis of a heparan sulfate with antithrombotic activity secreted by endothelial cells in culture. The stimulation is concentration dependent and specific for the endothelial cell. The [35S]-heparan sulfate synthesized in the presence of heparin and/or the tested antithrombotic agents has shown a high degree of sulfation of the iduronic acid residues as revealed by the analyses of the disaccharide products formed from the heparan sulfate by the action of bacterial heparitinases. The features of the above compounds in common with heparin are their polymeric nature and a high change density, as well as their pharmacological activities as potent antithrombotic agents "in vivo". These combined observations reinforce the proposition that the antithrombotic activity of heparin, low molecular weight heparins and the chemically modified polysaccharides could be related to the increased production of this peculiar heparan sulfate by endothelial cells.

Animals↗

PubMed1994

Protamine sulfate neutralization of the anticoagulant activity of Aprosulate, a synthetic sulfated lactobionic acid amide.

Aprosulate or lactobionic acid is a highly sulfated analogue of heparin which is currently undergoing clinical trials in Europe as a potential antithrombotic drug. Aprosulate exerts a strong anticoagulant effect in plasma as a result of its interaction with heparin cofactor II. In this study, the ability of protamine sulfate to neutralize the anticoagulant activity of Aprosulate was investigated. In vitro, ex vivo, and in vivo coagulation studies were performed using various clotting assays such as the APTT, Heptest, and thrombin time as a measure of the anticoagulant activity of Aprosulate. In the first study, protamine sulfate when administered in vitro to plasma samples containing various concentrations of Aprosulate was found to effectively neutralize the anticoagulant activity of the Aprosulate in both normal human and normal monkey plasma systems. However, the relative index of neutralization of Aprosulate was assay dependent. Protamine sulfate was also found to antagonize the anticoagulant effects of Aprosulate in an ex vivo study. The ex vivo supplementation of protamine sulfate to plasma samples collected at various time intervals following the subcutaneous administration of Aprosulate to a group of primates completely neutralized the anticoagulant activity of the Aprosulate. In a third in vivo study, protamine sulfate when injected intravenously into the bloodstream of a group of primate was found to completely neutralize the anticoagulant effects of a previously administered dosage of Aprosulate. The results of these three studies clearly suggest that protamine sulfate can be used to effectively neutralize the anticoagulant activity of Aprosulate.

Animals↗

PubMed1994

Feasibility study of heparin mass calibrator as a GPC calibrator for heparins and low molecular weight heparins.

The proposed European Pharmacopoeial (EP) method for molecular weight determination of low molecular weight heparins (LMWHs) has been shown to have a range which is too narrow to allow for the accurate molecular weight determinations of all LMWHs. We have recently shown that a chemically degraded benzyl ester of unfractionated heparin, ITH-3, is a better calibrator using this methodology. Data is presented here which indicates that this calibrator cannot only be used to determine the molecular weights of LMWHs but also of unfractionated heparins. Therefore, it is now renamed heparin mass calibrator or HMC because of this extension of range. Weight average molecular weight, number average molecular weight, peak molecular weight, and dispersity values were calculated using the HMC calibration and a reference narrow-range 19-calibrator method for various LMWHs and unfractionated heparins. Values for the parameters calculated using the HMC calibration were found not to be significantly different from those of the reference method until the molecular weight exceeded 15.0 kDa. In contrast, the molecular weight profile obtained with the proposed EP method was significantly different from the reference method for samples > 8.0 kDa. The range exhibited by the HMC calibrator should allow it to be used for both LMWHs and unfractionated heparins.

Chromatography, High Pressure Liquid↗

PubMed1993

Ectopic ACTH syndrome due to bilateral ovarian androblastoma with double, gynandroblastic differentiation in one ovary.

A case of fulminant Cushing's syndrome due to an ectopic ACTH secretion in a patient with bilateral ovarian sex-cord stromal tumour is reported. Surgical resection of the ovaries as well as the inhibitors of steroid synthesis and cytostatics caused only transient improvement because the widespread neoplastic dissemination progressed very quickly.

ACTH Syndrome, Ectopic↗

PubMed1993

Phase I--study with aprosulate, a new synthetic anticoagulant.

This paper describes the first human study with aprosulate, a new chemically synthesized anticoagulant with a defined molecular structure and a molecular weight of 2388. Twelve healthy male volunteers received subcutaneous injections of placebo on the first day followed by ascending doses of aprosulate in the range of 0.25 mg/kg to 2.0 mg/kg body weight on alternate days. Anticoagulant, pharmacokinetic and safety parameters were assessed for 48 hours after each injection. The activated partial thromboplastin time and the Heptest showed a dose-dependent increase for up to ten hours after each application. A trend towards prolongation of the bleeding time was indicated with higher doses. In general, the tolerance was good. Plasma transaminase concentrations were raised in some volunteers but returned spontaneously to normal during or after the study.

Adolescent↗