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Biomedical subjects

H J Hertfelder

Publications and source records attributed to H J Hertfelder.

18 recordsLinked to original sources
PubMed2001

The fibrinolytic system in chronic renal failure.

BACKGROUND: Patients with chronic renal failure (CRF) face a high risk of cardiovascular morbidity and mortality. Impaired fibrinolysis has recently been acknowledged to function as a risk factor for cardiovascular ischemic complications. Whether changes in fibrinolytic function contribute to the increased cardiovascular risk in CRF, however, remains unclear. METHODS: In the present study, tissue-plasminogen activator (t-PA) and its main antagonist plasminogen activator inhibitor-1 (PAI- 1) were determined in 12 subjects with normal renal function (group A) [serum creatinine (Cr) <1.3 mg/dl], 24 patients with impaired renal function (Cr 1.3-6.5 mg/dl) (group B) and 22 patients with endstage renal disease (ESRD) on hemodialysis (Cr>6.5 mg/dl) (group C). RESULTS: Plasma concentrations of PAI-1 and t-PA antigen as well as the PAI-1:t-PA molar ratio were unchanged in group B as compared to group A. However, in ESRD patients (group C), t-PA concentrations markedly decreased [13.7 +/- 2.9 ng/ml vs. 32.8 +/- 4.7 ng/ml (group B, p <0.01) and 35.4 +/- 8.4 ng/ml (group A, p <0.01)] while PAI-1 antigen concentrations remained in the control range. Thus, the PAI-1:t-PA molar ratio significantly increased in group C patients [12.4 +/- 4. 0 vs. 6.0 +/- 2.5 (group B; p<0.01) and 4.5 +/- 1.7 (group A; p<0.01]. CONCLUSIONS: From our data it may be suggested that fibrinolysis is markedly disturbed in ESRD due to a decreased availability of t-PA. Thus, it may be speculated that the development of atherothrombotic events in hemodialysis patients is, at least in part, due to an impaired fibrinolysis.

Adult↗
PubMed2001

[An uncommon cause of severe soft tissue bleeding during phenprocoumon treatment].

HISTORY AND ADMISSION FINDINGS: A 66-year-old patient presented to our clinic with extensive left arm and left flank haematomas, anaemia, a prolonged activated partial thromboplastin time (aPTT), and reduced factor IX activity 6 weeks after prosthetic mechanical aortic valve implantation. INVESTIGATION: Treatment with both vitamin K and a single injection of factor IX concentrate led to normalization of the activated partial thromboplastin time and factor IX activity, which remained constant for several days. No acquired factor IX inhibitor was detectable. Analysis of exon 2 of the factor IX gene revealed a C-->T mutation in codon 10 of the propeptide region, resulting in the substitution of alanine by valine. Echocardiography revealed a significant paravalvular leak. TREATMENT AND COURSE: The substitution of valine for alanine in the factor IX propeptide leads to an impaired affinity of factor IX to the vitamin K-carboxylase complex. In this situation, treatment with coumarin derivatives can profoundly reduce factor IX activity and result in severe bleeding episodes. This patient was re-exposed to warfarin under close hematological monitoring. After 4 days factor IX activity had decreased to 15%, which was associated with an increase of the aPTT and a mild decrease of the prothrombin time. Due to rapid progression of the paravalvular leak and almost impossible long-term orale anticoagulation with coumarin derivatives, we recommended replacement of the prosthetic mechanical valve with a biological device. CONCLUSION: The development of severe bleeding in the context of initiating warfarin therapy raises the suspicion of a factor IX propeptide mutation. The initial screening test is the activated partial thromboplastin time, which is elevated in the presence of the mutation. If concomitantly diminished factor IX activity is found the factor IX propeptide mutation should be excluded. Use of lifelong coumarin derivatives is contraindicated in patients with this mutation. However, a general screening of the activated partial thromboplastin time after coumarin initiation is not justified by cost/benefit analysis.

Aged↗
PubMed2000

[Renin-angiotensin-aldosterone system and fibrinolysis].

Experimental, genetic and clinical evidence suggests that the renin-angiotensin-aldosterone system (RAAS) may participate in the pathogenesis of thromboembolic cardiovascular disorders such as coronary heart disease. This interrelationship may involve mechanisms other than changes in arterial blood pressure. In addition to various possible interactions, accumulating evidence suggests that the RAAS is involved in the regulation of the fibrinolytic system. Several recent studies have shown that stimulation of the RAAS may be associated with an activation of plasminogen activator inhibitor 1 (PAI-1). Since profibrinolytic factors (especially tissue plasminogen activator [t-PA]) remain unchanged, increased activity of the RAAS may thus alter the fibrinolytic balance towards a decreased fibrinolytic activity. These findings may be of special importance for a variety of clinical problems such as the long-term effect of a low NaCl-intake on cardiovascular morbidity and mortality and the possible value of drugs indirectly or directly interfering with the RAAS such as diuretics, ACE-inhibitors and angiotensin II Type 1 (AT1) receptor antagonists.

Aldosterone↗
PubMed2000

Fibrinolytic function in diuretic-induced volume depletion.

Accumulating evidence suggests that the renin-angiotensin system (RAS) may participate in the regulation of fibrinolytic function. In clinical studies, however, angiotensin-converting enzyme (ACE) inhibitors and the angiotensin II receptor antagonist losartan have failed to consistently affect endogenous fibrinolysis. Because such an effect may depend on the degree of prestimulation of the RAS, we have studied parameters of fibrinolytic function in 15 healthy volunteer subjects during baseline (day 1) and after 10 days of treatment with 25 mg of hydrochlorothiazide (HCT)/day (day 11). On the last day of the study (day 12), a single oral dose of 50 mg of losartan was given to the volunteers in addition to HCT and fibrinolytic function was assessed at the peak effect of losartan (5 h later). Plasma renin activity (PRA) was significantly stimulated during diuretic treatment (1.35 +/- 0.21 v 0.34 +/- 0.06 ng mL(-1) x h(-1) [P < .001]) and further increased after losartan (6.39 +/- 1.16 ng mL(-1) x h(-1) [P < .001]). No effects of either the diuretic or losartan could be observed on tissue-type plasminogen activator (t-PA) antigen concentration and activity. However, 10 days of treatment with HCT significantly increased plasminogen activator inhibitor-1 (PAI-1) antigen (26.8 +/- 5.8 v 21.1 +/- 3.4 ng/mL [p = .037]). In addition, PAI-1 activity was also tentatively raised by HCT treatment (5.48 +/- 1.82 v 3.88 +/- 0.79 IU/mL [P = .067]). In spite of the marked further rise in PRA after losartan, the stimulation of PAI-1 antigen and activity was blunted by losartan (24.4 +/- 3.6 ng/mL and 4.55 +/- 0.99 IU/mL, respectively). Our results demonstrate that volume depletion induced by HCT treatment is associated with a rise in PAI-1. Acute administration of losartan is capable of blunting this effect, suggesting that the angiotensin II type 1 receptor may participate in this effect of angiotensin II.

Adult↗
PubMed2000

Effects of the mineralocorticoid fludrocortisone on fibrinolytic function in healthy subjects.

Recent evidence suggests that the renin-angiotensin-aldosterone system (RAAS) may participate in the regulation of fibrinolytic function. Angiotensin II (Ang II) is the primary candidate to mediate this inter-relationship, since this peptide is capable of stimulating plasminogen activator inhibitor-1 (PAI-1) in vitro and in vivo. It has been suggested that aldosterone may also modulate fibrinolysis, possibly by interacting with Ang II. The present study therefore investigates the effect of short-term treatment with the synthetic mineralocorticoid fludrocortisone (F) on fibrinolytic function. Ten healthy male volunteers, aged 25 to 30 years, on a constant intake of 160-180 mmol Na(+) and 60-80 mmol K(+), were studied on a control day (C1), after two days of oral administration of F (0.1 mg b.d.), and again three days after cessation of F (C2). F was associated with a marked decrease in plasma renin activity (PRA) from 0.91 +/- 0.45 ng ml(-1) h(-1) to 0.34 +/- 0.29 ng ml(-1) h(-1) (p=0.005), which returned to the baseline range at C2 (0.65 +/- 0.45 ng ml(-1) h(-1); p=0.032). The experimental protocol was not associated with significant changes in the activity or antigen concentration of tissue plasminogen activator (t-PA). PAI-1 exhibited a circadian rhythm with highest values at 0800 hours (41.8 +/- 9.1 ng/ml), decreasing by 1230 hours (22.6 +/- 5.9 ng/ml), with a further decrease at 1630 hours (12.3 +/- 3.1 ng/ml). At all three time points, PAI-1 remained unchanged by the mineralocorticoid. Our results therefore do not support a major mineralocorticoid effect on PAI-1. However, our study does not exclude a modulatory role of F, since unchanged PAI-1 could be observed in spite of a marked suppression of the RAAS.

Adult↗
PubMed1999

Lethal capillary leak syndrome after a single administration of interferon beta-1b.

Interferon beta-1b (IFNbeta-1b) is a potent immunomodulatory drug in the treatment of MS. We report a lethal capillary leak syndrome after the administration of IFNbeta-1b in a patient with disseminated white matter disease, monoclonal gammopathy, and acquired C1 inhibitor (C1-INH) deficiency. IFNbeta-1b may cause a transient release of proinflammatory cytokines finally resulting in an uninhibited activation of the complement cascade in patients with C1-INH deficiency.

Adult↗
PubMed1999

Effects of captopril on fibrinolytic function in healthy humans.

Several lines of evidence point to an interrelation of the renin angiotensin system (RAS) with the endogenous fibrinolytic system. In the present study, we have therefore investigated the effect of the ACE-inhibitor captopril on various parameters of the fibrinolytic system in healthy volunteer subjects. 10 male subjects aged 28-38 years were given captopril 25 mg b.i.d. over 2 weeks. Venous blood was drawn before and at the end of the treatment period at 09.00 AM, after the volunteers had received their last dose of captopril by 07. 30 AM. Blood samples were processed for the determination of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1). Both parameters were determined with respect to their abundance (as antigen concentrations) and function (activity). In addition, the concentration and activity of the von Willebrand factor were also determined. Two weeks of captopril treatment had no significant effect on any of the above mentioned parameters. Our results thus show that short-term treatment with the ACE-inhibitor captopril, at least in healthy subjects on an unrestricted NaCl intake, does not affect the fibrinolytic balance between t-PA and PAI-1 or the von Willebrand factor.

Adult↗
PubMed1999

Standardization of the PFA-100(R) platelet function test in 105 mmol/l buffered citrate: effect of gender, smoking, and oral contraceptives.

The PFA-100(R) (PFA) diagnostic system for the detection of platelet dysfunction was evaluated to determine reference ranges in a normal population. The PFA determines the primary haemostasis capacity (PHC) of anticoagulated whole blood, expressed by the system's closure time (CT). In this study the CT reference ranges were determined for blood samples collected in 105 mmol/l (3.2%) buffered citrate and the effect of gender, smoking, and use of oral contraceptives on reference ranges was assessed. Each of the 309 healthy blood donors from five blood centres was confirmed to have normal platelet function before inclusion in the study. Blood samples were tested in duplicate with both the collagen/epinephrine (Col/Epi) and collagen/ADP (Col/ADP) test cartridges. PFA reference ranges (90% central intervals of measured closure times) for both cartridge types were similar for all groups. Subgroup analysis showed that neither gender nor oral contraceptive usage had any effect on PHC. The 95% cut-off value for the Col/Epi CT was slightly higher for smokers than for non-smokers, an effect more pronounced in female than in male donors. However, the small difference did not justify establishment of specific reference ranges for smokers. Data from all included subjects were pooled to calculate the CT reference ranges for blood samples collected in 105 mmol/l buffered citrate (Col/Epi 82-150 s; Col/ADP 62-100 s). Normal levels of fibrinogen, as well as normal platelet counts and normal haematocrit levels, appeared not to influence the PHC. Because slight but significant differences of the reference ranges were observed between some of the participating sites, in-house confirmation of these reference range guidelines is recommended.

Adolescent↗
PubMed1998

[Progress of acute liver failure and indications for liver transplantation].

OBJECTIVE: To analyse the course of acute liver failure and the indications for liver transplantation. PATIENTS AND METHODS: In 16 patients who developed acute liver failure between July 1992 and July 1997 the indications for liver transplantation and total survival time were analysed retrospectively. RESULTS: Intensive medical care (ventilation, dialysis) was necessary in 60% of the patients to bridge organ failure until liver transplantation. In 14 patients liver transplantation was indicated. Eleven of the patients, with a minimal Quick value of less than 10%, presented with the prognostically poorest London criteria. In two patients the combination of three additional criteria of the London classification led to liver transplantation being indicated. In one patient with Wilson's disease the transplantation was undertaken despite good clotting factor synthesis, because an encephalopathy occurred. In two patients liver transplantation was not undertaken even though indicated, in one because liver functions improved, in the other because necrotizing pancreatitis had occurred. In another patient, who had been poisoned by eating the mushroom Amanita phalloides, the attempted transplantation was cut short, because intestinal necrosis had developed, and the patient died during the operation. Nine of the eleven patients who had a transplantation and three of the four treated conservatively survived. CONCLUSION: The 60-day survival rate in this series, achieved in a recently established transplantation programme, is high (12 of 16; 75%), being comparable to those in larger transplantation centres.

Adult↗
PubMed1998

Antihypertensive drug treatment and fibrinolytic function.

Thromboembolic complications such as ischemic stroke and myocardial infarction are significantly more frequent in patients with arterial hypertension. From the available intervention studies, it appears that pharmacologic treatment of hypertension-at least with diuretics and beta-blockers-may more effectively protect against cerebrovascular as compared to coronary thromboembolic events. Whether other antihypertensive substances provide a more effective protection with respect to cardiac morbidity and mortality is the subject of numerous studies presently underway. These studies will help to answer the question of whether the extent of protection from coronary events during antihypertensive treatment depends on factors beyond blood pressure control. The fibrinolytic system is crucially involved in the pathogenesis of thromboembolic events. One determinant of this system is the balance between plasminogen activators (tissue-type plasminogen activator [t-PA]) and inhibitors (plasminogen activator inhibitor 1 [PAI-1]). Experimental and clinical evidence suggests that at least some of the drugs used in the treatment of hypertension may alter the activity of the fibrinolytic system. Scarce and controversial data with respect to such an interaction exist with respect to diuretics, beta-blockers, and calcium antagonists. In addition, experimental evidence demonstrates that PAI-1 is stimulated by angiotensin II (A II), whereas t-PA is activated by bradykinin. Thus, antihypertensive drugs acting within the renin angiotensin system should exert effects also within the fibrinolytic system. However, results from clinical studies with angiotensin converting enzyme (ACE) inhibitors and A II receptor antagonists do not unequivocally support such a concept. The discrepancy in the results may, at least in part, be explained by studies performed in healthy volunteer subjects showing that ACE inhibition profoundly affected fibrinolysis only during stimulation of the renin angiotensin system by NaCL restriction.

Adrenergic Antagonists↗
PubMed1997

Severe bleeding in two patients due to increased sensitivity of factor IX activity to phenprocoumon therapy.

Two male patients with severe and recurrent bleeding episodes under phenprocoumon therapy are reported. Both patients exhibited a strong decrease of their factor IX activities below 1% of normal, whereas the activities of the vitamin K-dependent factors prothrombin, VII, and X were found to be within or above the expected therapeutic ranges of 20-40%. Upon removal of phenprocoumon and substitution with vitamin K, the factor IX activities increased to 85% and 55%, respectively. Reexposition to phenprocoumon in one patient confirmed the rapid and selective decrease of the factor IX activity. These findings provide the first report of an abnormally high sensitivity of factor IX activity to oral anticoagulant therapy.

Adult↗
PubMed1997

Missense mutations at ALA-10 in the factor IX propeptide: an insignificant variant in normal life but a decisive cause of bleeding during oral anticoagulant therapy.

Bleeding complications are the most common and unwanted side-effect of oral anticoagulant therapy. We report three patients in whom mutations in the factor IX (FIX) propeptide were found to cause severe bleeding during coumarin therapy. Strikingly, the bleeding occurred within the therapeutic ranges of the prothrombin time (PT) and international normalized ratio (INR). In all three patients coumarin therapy caused an unusually selective decrease of FIX activity (FIX:C) to levels below 1-3%. Upon withdrawal of coumarin, FIX:C increased to subnormal or normal values of 55%, 85% and 125%, respectively. Analysis of the FIX gene revealed two different missense mutations affecting the Ala-10 residue in the propeptide coding region: Ala[GCC] to Val[GTC] in two patients and Ala[GCC] to Thr[ACC] in one patient. No further mutation was detected by screening 195 random blood donors for mutations at Ala-10, thus excluding a frequent polymorphism at this position. The mutation in the FIX propeptide at a position which is essential for the carboxylase recognition site causes a reduced affinity of the carboxylase enzyme to the propeptide. This effect leads to an impaired carboxylase epoxidase reaction which is decisively triggered by the vitamin K concentration. Determination of FIX and APTT in addition to PT and INR is therefore recommended in coumarin-treated patients with an uncommon bleeding pattern.

Administration, Oral↗
PubMed1996

[Recurrent arterial thromboembolism in hereditary hypoplasminogenaemia].

HISTORY: A 26-year-old man sustained a wasp bite 5 years ago which caused arterial embolism to the right brachial artery. Now he again had a wasp bite with allergic reaction and an arterial embolus to the left brachial artery. 2 days later, after embolectomy and heparinisation, he had a cerebrovascular accident due to an embolus to the left internal carotid artery. 15 days later, despite oral anticoagulation (Quick value 10%), he had an embolism to the left femoral artery. INVESTIGATIONS: The source of the emboli was found by echocardiography to be a spherical floating thrombus on the aortic valve. The plasminogen level was only 45-61%. His mother and sister also had a low plasminogen level, i.e. he had congenital plasminogen deficiency. TREATMENT AND COURSE: At surgery, when the thrombus had been removed, a slit-like defect was found on one of the aortic leaflets and covered with a pericardial patch. At first heparin then phenprocoumon were administered, plus 250 mg ticlopidine twice daily. There have been no further complications. CONCLUSION: As the patient's fibrinolysis activity was normal, additional, probably allergic, factors must have been present to disturb the equilibrium between thrombogenesis and fibrinolysis thus causing thrombosis at a predisposed site.

Adult↗
PubMed1994

Pharmacokinetics of vasoactive substances administered into the human corpus cavernosum.

The pharmacokinetics of vasoactive substances injected into the corpus cavernosum for the treatment of erectile dysfunction have not been investigated to date. We measured the local intracavernous and peripheral venous concentration curves of papaverine and prostaglandin E1, and its primary metabolite 15-keto-13,14-dihydro-prostaglandin E1 in an intra-individual comparison after intracavernous injection. Papaverine was measured with high performance liquid chromatography and prostaglandin E1 was measured with a specially adapted radioimmunoassay. The results demonstrate that papaverine is slowly draining into the systemic circulation, showing slightly elevated levels in the peripheral blood 30 and 60 minutes after injection. Prostaglandin E1 shows a much faster decrease in local concentrations with no measurable increase in the periphery, probably due to the short half-time after lung passage. Measurement of the primary metabolite proves a local degradation of prostaglandin E1 in the corpus cavernosum into the biologically inactive 15-keto-13,14-dihydro-prostaglandin E1, which also shows a slight increase in the peripheral circulation due to the longer half-time of approximately 8 minutes. The data provide good explanation for the clinical finding of a markedly decreased incidence of priapism with the use of prostaglandin E1, which can be shown to be locally metabolized, compared to papaverine, which is retained in the corpus cavernosum in cases of nonvenogenic impotence.

Alprostadil↗
PubMed1994

Leukocyte proteinase release during storage of red cell concentrates.

The release of polymorphonuclear leukocyte proteinases in buffy-coat-depleted red cell concentrates was examined during a storage period of 35 days. Collagenase, gelatinase and elastase predominantly induce breakdown of connective tissue. However, when released by cell disintegration during red cell concentrate storage, the considerable proteolytic activities of these enzymes might influence the quality of the stored blood. During the observation period a considerable decrease in the polymorphonuclear leukocyte count was observed, accompanied by increases in the levels of collagenase, gelatinase and elastase. Compared with the enzyme levels on the day of red cell concentrate preparation, collagenase increased 20-fold, gelatinase 6-fold and elastase 100-fold during the storage period. When cells were treated with the chemoattractant hexapeptide, N-formyl-nle-leu-phe-nle-tyr-leu, and the degranulation promoting cytochalasin B, gelatinase exhibited the highest secreted concentration in the freshly prepared red cell concentrate, exceeding the maximum of spontaneously released elastase by 4- to 6-fold. However, these compounds stimulated enzyme release only during the first day after red cell concentrate preparation. Thereafter, no differences between stimulated and non-stimulated samples were observed. The data indicate that polymorphonuclear leukocytes contain a large storage pool of proteolytic enzymes. These enzymes together with other polymorphonuclear leukocyte enzymes, e.g. hydrolases and oxidoreductases, might alter the erythrocyte membrane surface and thus influence the storage quality of the prepared red cell concentrate.

Blood Preservation↗