Simvastatin depresses blood clotting by inhibiting activation of prothrombin, factor V, and factor XIII and by enhancing factor Va inactivation

BACKGROUND

The mechanism of the antithrombotic action of statins is unclear. The aim of this study was to evaluate the effects of simvastatin on the coagulation process at sites of microvascular injury.

METHODS AND RESULTS

Tissue factor-initiated coagulation was assessed in blood samples collected every 30 seconds from bleeding-time wounds of 17 patients who had advanced coronary artery disease and total cholesterol levels of 224.6+/-11.8 mg/dL (mean+/-SEM). Quantitative Western blotting for time courses of fibrinogen depletion and activation of prothrombin, factor V, and factor XIII was performed before and after 3 months of simvastatin treatment (20 mg/d). Simvastatin induced reductions in total cholesterol (23%) and LDL-cholesterol (36%), which were accompanied by significant decreases in the rates of prothrombin activation (16.2+/-2.1%; P=0.004), formation of alpha-thrombin B-chain (27.4+/-1.8%; P=0.001), generation of factor Va heavy chain (29.7+/-3.1%; P=0.007) and factor Va light chain (18.9+/-1.2%; P=0.02), factor XIII activation (19.8+/-1.3%; P=0.001), and fibrinogen conversion to fibrin (72.2+/-3%; P=0.002). Posttreatment fibrinopeptides A and B concentrations, determined by using high-performance liquid chromatography, were reduced within the last 30 seconds of bleeding. The 30-kDa fragment of the factor Va heavy chain (residues 307 to 506), produced by activated protein C, and the 97-kDa fragment of the factor Va heavy chain (residues 1 to 643) were released more rapidly after simvastatin treatment. The antithrombotic actions of simvastatin showed no relationship to its cholesterol-lowering action.

CONCLUSIONS

Simvastatin treatment depresses blood clotting, which leads to reduced rates of prothrombin activation, factor Va generation, fibrinogen cleavage, factor XIII activation, and an increased rate of factor Va inactivation. These effects are not related to cholesterol reduction.

Anti-inflammatory effects of simvastatin in subjects with hypercholesterolemia

AIMS

Beneficial effects of statins in preventing cardiovascular events may depend, at least in part, on their anti-inflammatory action. The aim of the study was to assess the influence of simvastatin and aspirin on serum levels of C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in hypercholesterolemic subjects.

METHODS AND RESULTS

In 33 asymptomatic men with total cholesterol (TC) >6.5 mmol l(-1) and in 25 men with coronary heart disease and borderline-high cholesterol levels (between 5.2 and 6.5 mmol l(-1)) chronically treated with low-dose aspirin (75 mg/d), serum levels of CRP, TNF-alpha, IL-6, and IL-8 were determined before and after a 3-month simvastatin therapy (20-40 mg daily). In the former group, these markers of inflammation were also measured before and after a 2-week treatment with aspirin (300 mg/d), implemented prior to and in combination with simvastatin. A distinct reduction of CRP and TNF-alpha was found in both groups; IL-6 levels were decreased only in subjects with marked hypercholesterolemia. Aspirin had no effect on the anti-inflammatory action of simvastatin.

CONCLUSIONS

In men with hypercholesterolemia simvastatin treatment lowers serum levels of CRP and proinflammatory cytokines. Low-dose aspirin does not add to the anti-inflammatory action of simvastatin.

A time-motion study of the activities of attending physicians in an internal medicine and internal medicine-pediatrics resident continuity clinic

PURPOSE

To describe the activities of attending physicians in a residency-based continuity clinic and to examine factors that affect their teaching of, supervision of, and interaction with residents.

METHOD

Six full-time board-certified faculty members (three internal medicine, three internal medicine-pediatrics) in an urban residency program participated in a descriptive observational time-motion study. The attending faculty were directly observed by "shadow" technique for 30 half-day sessions from April 1994 through September 1994. Each activity was measured by a trained research assistant using a digital stopwatch. The observed activities were assigned to one of 16 subcategories.

RESULTS

6,389 minutes of activities were observed. Activities were distributed among four general categories: direct contact with residents (43.1%), clinic operations (33.7%), personal and/or professional activities (18.0%), and miscellaneous time (5.2%). Attending physicians spent the most time in direct contact with residents when the patient-to-attending ratio was 10-14:1.

DISCUSSION

The activities of the clinic's attending physicians were quite varied. Less than half of their time in the clinic was spent in contact with residents. This contact time may be significantly increased by changes to clinic policies, such as optimizing the patient-to-faculty ratio and increasing administrative support for the clinic. These findings can be used as a reference point for studies of attending physicians' activities since the federally mandated rules changes regarding their responsibilities for supervising residents.

Successful coronary stent implantation in a patient with primary antiphospholipid syndrome

We report a 22-year-old man who successfully underwent coronary stent implantation after an acute myocardial infarction. Lupus anticoagulant and antibodies against cardiolipin and prothrombin were detected despite the absence of any underlying disease. Therefore, long-term oral anticoagulation was instituted and appeared to be effective. To our knowledge this is the first report on coronary stenting in primary antiphospholipid syndrome.

Gamma interferon administration to patients with atopic dermatitis inhibits fibrinolysis and elevates C1 inhibitor

Recombinant human gamma interferon was used to treat 10 atopic dermatitis patients. Recombinant gamma interferon was administered weekly for three consecutive days at 50 microg/M2 SQ for four weeks. All patients' dermatitis improved with recombinant gamma interferon therapy and plasma tumor necrosis factor-alpha levels rose with treatment. Recombinant gamma interferon treatment positively correlated with reduced total plasma fibrinolysis as measured by the fibrin lysis plate, plasmin-alpha2antiplasmin complexes, and tissue type plasminogen activator levels. Accordingly, plasminogen activator inhibitor levels increased. Treatment also was associated with a transient increase in thrombin-antithrombin III complexes. Recombinant gamma interferon resulted in a significant increase in C1 inhibitor antigen but not activity. Plasma prekallikrein, high molecular weight kininogen, and factor XII levels were not decreased. However, 5 of the 10 atopic dermatitis patients before therapy had circulating cleaved plasma high molecular weight kininogen detected on immunoblot, indicating prior kallikrein formation. The cleaved, circulating plasma high molecular weight kininogen disappeared in four out of the five original patients who were reexamined at one year after treatment. These combined data indicated that recombinant gamma interferon treatment reduced total plasma fibrinolysis. In untreated atopic dermatitis, circulating cleaved high molecular weight kininogen also may be a presenting manifestation.

Anticardiolipin, anti-beta(2)-glycoprotein I, antiprothrombin antibodies, and lupus anticoagulant in patients with systemic lupus erythematosus with a history of thrombosis

OBJECTIVE

To determine the clinical importance of anticardiolipin (aCL), anti-beta(2)-glycoprotein I (a beta(2)-GPI), antiprothrombin (aPT), and lupus anticoagulant (LAC) antibodies in patients with systemic lupus erythematosis (SLE) with and without a history of thrombosis.

METHODS

We studied 100 patients with SLE (32 with a history of thrombosis), 27 patients with a lupus-like disease (9 with a history of thrombosis), and 41 healthy volunteers, IgG and IgM aCL, antibodies to the protein cofactors (a beta(2)-GPI and aPT) were determined by ELISA. Eighty-six of 127 patients were also tested for LAC.

RESULTS

IgG aCL and LAC were associated with thrombosis but sensitivity (63 and 61%) and specificity (66 and 66%, respectively) of these tests were low. IgG and IgM a beta(2)-GPI were, respectively, 85 and 86% specific for a thrombotic history, but sensitivity was very low (32 and 29%). High IgG aCL were associated with the presence of a beta(2)-GPI and were 85% specific for thrombosis. There was no significant association between IgG or IgM aPT and thrombosis.

CONCLUSION

Only high levels of IgG aCL and presence of LAC and/or a beta(2)-GPI are relevant in defining a thrombotic subset of patients with SLE. Longitudinal prospective studies are needed to investigate the predictive value of the different antiphospholipid and protein cofactor antibodies.

Inhibition of thrombin generation by aspirin is blunted in hypercholesterolemia

Recent evidence indicates that aspirin inhibits thrombin generation in clotting blood. We noticed that this effect was less pronounced in patients with hypercholesterolemia. The aim of the study was to prove this observation. The effects of aspirin on thrombin generation were evaluated in (1) 46 healthy volunteers, 2 hours after ingestion of a single, 500-mg dose and (2) 28 survivors of myocardial infarction who took 300 mg aspirin/d for 2 weeks. In both populations, two well-matched subgroups were distinguished, using a serum cholesterol level of 6.2 mmol/L (240 mg/dL) and an LDL cholesterol level of 4.0 mmol/L (155 mg/dL) as borderline. Thrombin generation was monitored ex vivo in blood emerging from a skin microvasculature injury and additionally, in a single-dose study in vitro in recalcified plasma. Aspirin depressed thrombin generation in the group of subjects with serum cholesterol < 6.2 mmol/L and LDL cholesterol < 4.0 mmol/L but not in the group with high blood cholesterol levels. Inhibitory effects of aspirin were more pronounced after the 2-week treatment than after a single dose. There was a significant correlation between total serum cholesterol or LDL cholesterol and total amount of thrombin generated after aspirin treatment. In subjects with high blood cholesterol levels, thrombin generation was not affected by aspirin. Blunting of aspirin action in hypercholesterolemia might be explained by (1) alterations in platelet lipid-protein matrix that render their membrane proteins less accessible for acetylation by aspirin and (2) changes in composition and structure of plasma lipoproteins that diminish the chance of aspirin to interact with prothrombin.

Autoimmune phenomena in bronchial asthma with special reference to aspirin intolerance

We assessed the autoimmune status of 185 adult patients with bronchial asthma and 46 healthy subjects of similar sex and age. The patients were divided into groups with: (1) aspirin-induced asthma (AIA) (n = 80); (2) intrinsic asthma with good aspirin tolerance (n = 46); and (3) atopic asthma (n = 59). Antinuclear antibodies (ANA) at a titer of > or = 1:40 were present in the serum of 55% of the patients with AIA, 41% of those with intrinsic asthma, 39% of those with atopic asthma, and 11% of the healthy subjects, with the difference between each patient group and the healthy subjects being statistically significant (p < 0.05). The fluorescence staining pattern of ANA on Hep-2 cells was mainly speckled, but the precise antigen specificity of the antibodies could not be identified with reference sera against extractable nuclear antigens. None of the subjects exhibited anti-double stranded deoxyribonucleic acid (anti-ds-DNA) or anti-neurtrophil cytoplasmic antibodies (ANCA). Positive ANA were associated with signs of complement activation, the presence of rheumatoid factor, and circulating immune complexes. Clinical signs of autoimmunity, evidenced by rheumatic symptoms, cold sensitivity, and Raynaud's phenomenon, were more common among the patients who tested positively for ANA. The assessment of autoimmunity may help in better characterizing patients with asthma and understanding various symptoms of the disease. Any causal relationship between asthma and autoimmunity remains to be established.

The dual diagnosis of attention-deficit/hyperactivity disorder and substance abuse: case reports and literature review

BACKGROUND

It is now recognized that attention-deficit/hyperactivity disorder (ADHD) may persist into adulthood. A number of studies have found an association between ADHD and substance abuse. This article describes three adult patients with both ADHD and substance abuse who were treated successfully with psychostimulants. A review of the relevant literature is included.

METHOD

The patients were drawn from a university-based referral center for adults with ADHD. Evaluations for ADHD and substance abuse were completed. Medical therapy and follow-up were completed by the first author.

RESULTS

All of the patients responded to psychostimulants and have remained abstinent from alcohol and other drugs for the past 2 to 3 years.

CONCLUSION

This case series and review of the literature suggest that specific treatment for ADHD with psychostimulants is feasible in patients who also have substance abuse. Future studies should evaluate the prevalence of this "dual diagnosis" and the efficacy of differing management strategies.

Humoral immunosuppression in men exposed to polycyclic aromatic hydrocarbons and related carcinogens in polluted environments

We evaluated humoral immunity by measuring IgG, IgA, IgM, and IgE concentrations in 274 male workers in an iron foundry in Cracow, Poland. There were two groups: 199 coke oven workers and 76 cold-rolling mill workers. The groups were similar with respect to age, length of work (average 15 years), and smoking habits. Exposure to polycyclic aromatic hydrocarbons (PAHs), assessed by personal and area monitoring, ranged from 0.2 to 50 micrograms/m3 benzo[a]pyrene in coke plant workers and was of 3-5 magnitudes higher than in the cold-rolling mill employees. Comparison of the two groups revealed a marked depression of mean serum IgG and IgA in coke oven workers (p < 0.001, Student's unpaired t-test). In the same subjects, serum IgM had a tendency to decrease, whereas serum IgE showed a trend toward higher values. Thus, workers exposed chronically to complex mixtures of air pollutants, composed primarily of PAHs, develop immunosuppression. It remains to be established whether the immunosuppression described here is related to the frequent development of lung cancer reported in coke plant employees. Workers exposed chronically to PAHs should have serum immunoglobulins monitored regularly.

Inhibition of platelet adhesion to surfaces of extracorporeal circuits by disintegrins. RGD-containing peptides from viper venoms

Previous studies indicate that exposure of fibrinogen receptors associated with glycoprotein IIb/IIIa complex contributes to platelet loss during cardiopulmonary bypass. Recently, we isolated a number of RGD (Arg-Gly-Asp)-containing, low molecular weight, cysteine-rich peptides from viper venoms. These peptides, which we propose to call "disintegrins," block platelet-fibrinogen interaction and platelet aggregation. We compared the effect of RGDS (Arg-Gly-Asp-Ser) and four disintegrins (echistatin, flavoridin, albolabrin, and bitistatin) on platelet behavior in a membrane oxygenator. During simulated extracorporeal circulation for 2 hours, platelet count decreased to about 30% of initial values. Addition of echistatin (60-200 nM), albolabrin (60-200 nM), bitistatin (60 nM), and flavoridin (45 nM) significantly inhibited platelet loss in the circuit. RGDS (33 microM) did not show any significant inhibitory effect. ADP-induced platelet aggregation was inhibited in samples of platelet-rich plasma taken from the circuits containing disintegrins. However, echistatin appeared to be a more potent inhibitor of platelet aggregation, whereas albolabrin and flavoridin interfered more selectively with platelet loss from the circuit. Echistatin prevented the accumulation of glycoprotein IIIa on the surface of the circuit. Echistatin (60-200 nM), flavoridin (45 nM), bitistatin (60 nM), and albolabrin (200 nM) significantly inhibited the loss of beta-thromboglobulin from platelets into circulating plasma. Electron microscopy studies demonstrated shape change but not degranulation in platelets circulating in the presence of 200 nM echistatin. On the other hand, this peptide (up to 1,000 nM) did not prevent loss of alpha granules and beta-thromboglobulin from thrombin-stimulated platelets, although it prevented their aggregation. In conclusion, disintegrins protect platelets in the circuit by preventing their adhesion to surfaces and, therefore, preventing fragmentation of adhered platelets under the shear stress of flowing blood. This study indicates that disintegrins may be potential candidates for platelet protection during cardiopulmonary bypass.

Fibrinogen receptors in platelet adhesion to surfaces of extracorporeal circuit

The role of platelet fibrinogen receptors and platelet-protein interaction in platelet consumption during simulated cardiopulmonary bypass was investigated. In five recirculation experiments, with whole blood, the platelet count fell to 13% of initial values and in two experiments, with blood from patients with Bernard-Soulier syndrome, to 3% of normal values. However, in three experiments with blood from the patients with Glanzmann's thrombasthenia, the platelet count decreased to 69% of initial values. The extent of platelet consumption in normal blood was diminished to only 72% by addition of 0.5 microM prostaglandin E1 (PGE1) (5 experiments) and to 80% by precoating surfaces of the circuit with 2.5% human albumin (5 experiments). beta-Thromboglobulin antigen (beta TG) loss from platelets was associated with thrombocytopenia. The extent of beta TG loss was significantly reduced by the addition of PGE1 to blood or precoating surfaces with albumin. Proteins adsorbed on the surface of the circuit exposed to normal blood were removed with 0.5% Triton X-100. Some of these proteins were identified to be glycoprotein IIIa (GPIIIa) (3.4-4.3 micrograms/ml), beta TG (1.0-1.6 micrograms/ml), and fibrinogen (1.9-3.7 micrograms/ml). The amount of GPIIIa recovered in the Triton X-100 eluates correlated with the number of platelets lost during recirculation. These studies indicate that exposure of fibrinogen receptors associated with GPIIb-GPIIIa complex contributes to platelet consumption during cardiopulmonary bypass.

Quantitation of platelet preservation with prostanoids during simulated bypass

Extensive blood-synthetic surface interactions during cardiopulmonary bypass produce adverse platelet alterations that can contribute to excessive blood loss following open cardiac surgery. These platelet alterations can be reduced by temporary inhibition of platelet function. In order to define further an optimal method of platelet inhibition during blood-synthetic surface contact, we quantitated platelet functional and structural alterations that occur during simulated extracorporeal circulation (SEC) despite platelet inhibition with Iloprost (ZK) or PGE1. Five-hundred milliliters of fresh heparinized human blood were recirculated for 2 hr in a circuit consisting of silicone rubber components and a spiral coil membrane oxygenator. When blood was recirculated for 2 hr without drug, platelet counts fell significantly to 46 +/- 7% (mean +/- SEM) of initial levels (P less than 0.01); mean platelet volume decreased from 6.90 +/- 0.25 micron3 to 6.05 +/- 0.33 micron3 (P less than 0.01); platelet dispersion increased from 1.73 +/- 0.02 to 2.14 +/- 0.09 (P less than 0.01) and platelets no longer aggregated in response to epinephrine or thrombin. In contrast, when blood was recirculated with either ZK (0.003 microM) or PGE1 (0.3 microM), platelet counts were significantly preserved when compared to blood recirculated without drug (82 +/- 5% and 89 +/- 7%, respectively; P less than 0.01); mean platelet volume did not change; and dispersion only increased from 1.74 +/- 0.02 to 1.85 +/- 0.04 (P less than 0.05). However, following gel filtration, platelets recirculated with PGE1 always responded less than platelets merely incubated with PGE1 when challenged with either epinephrine (50 vs 75%, P less than 0.05) or thrombin (37 vs 65%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Bleeding time and PAF-acether-induced platelet aggregation in atopy

In a double-blind cross-over study 20 mg of aspirin or placebo were administered to 18 patients with respiratory atopy without eczema and to 12 healthy controls. Mean bleeding time before administration of either aspirin or placebo was on average about 1 min. longer in atopics than in the controls, and this difference was significant (p 0.05). Atopics' platelets also aggregated less well in response to arachidonic acid in comparison to controls. On the contrary, no difference in platelet aggregability was detected in response to either PAF-acether alone or to combination of subthreshold, synergistic concentrations of PAF-acether and collagen. Aspirin at a dose used did not affect either bleeding time or platelet aggregability. Thus, in respiratory atopy there exists a moderate hemostatic imbalance, the reason of which remains to be established.

Loss of fibrinogen receptors from the platelet surface during simulated extracorporeal circulation

In vitro recirculation of fresh human heparinized blood in an extracorporeal circuit with a membrane oxygenator decreased fibrinogen-induced platelet aggregation and diminished the number of fibrinogen receptors and glycoprotein IIb/IIIa (GPIIb/GPIIIa) antigenic sites on the platelet surface. In seven experiments, the mean +/- SD Km value for fibrinogen (i.e., molar concentration of fibrinogen required to cause 50% of the maximal rate of aggregation) was 1.58 X 10(-7) mol/L +/- 0.68 X 10(-7) mol/L. After recirculation, this value increased to 3.8 X 10(-7) mol/L +/- 1.94 X 10(-7) mol/L (P less than or equal to 0.025). The maximal aggregation rate of chymotrypsin-treated platelets decreased by 40% after 2 hours of recirculation (P less than or equal to 0.025). The number of fibrinogen receptors on platelets, which were treated with chymotrypsin after a recirculation, decreased from 41,370 +/- 24,000 to 13,230 +/- 10,230/platelet under the same conditions (P less than or equal to 0.025). The number of antigenic sites for monoclonal antibody reacting with GPIIb/GPIIIa complex of adenosine diphosphate-stimulated platelets decreased from 34,200 +/- 5,940 to 19,500 +/- 9,680/platelet after recirculation (P less than or equal to 0.025). Prostaglandin E1 (0.3 mumol/L) in the perfusion circuit preserved the ability of platelets to react with fibrinogen. In conclusion, the loss of fibrinogen receptors from the surface of platelet membranes results from the interaction of platelets with the surfaces of perfusion circuits.

Observer variation in lower limb venography

Three radiologists examined 34 venograms (68 limbs) performed supine without fluoroscopy for evidence of thrombosis. At 11 major veins in each limb they stated whether thrombus was "absent," "doubtful," "presumed" or "definite" or expressed " "no opinion." Data were analyzed by using the kappa statistic, which corrects for chance agreement. Results were compared with those from a previous study in which two of the observers assessed venograms performed under fluoroscopic control with the patient semi-erect. In the present study observers expressed "no opinion" much more often, particularly for anterior tibial and iliac veins. With these examinations excluded, the extent of observer variation was similar in the two studies, disagreement about the presence of thrombus occurring in about 10% of examinations. The frequency with which the diagnosis of thrombus remains in doubt severely limits the value of venography performed supine without fluoroscopy. Fluoroscopically-controlled examinations in the semi-erect position are preferable.

Role of kidney in the catabolic clearance of human platelet antiheparin proteins from rat circulation

Stimulated platelets release at least two antiheparin proteins: platelet factor 4 (PF4) and low affinity platelet factor 4 (LA-PF4) from which beta-thromboglobulin (beta TG) is derived. We have found previously marked elevation of LA-PF4/beta TG antigen in platelet poor plasma of patients with chronic renal failure, whereas levels of PF4 remained normal. Therefore, we examined the role of the kidneys in the metabolic clearance of LA-PF4/beta TG and PF4. The supernates of aggregates of thrombin-stimulated human platelets were injected into sham operated control rats, nephrectomized rats, and into rats with acute ureteral ligation. The disappearance of human LA-PF4/beta TG antigen and PF4 in rat plasma determined by specific radioimmunoassays followed biphasic exponential curves. The half-lives (t1/2) for the fast and slow components of LA-PF4 in control rats were 6.4 and 68.4 min. Nephrectomy significantly increased these times to 9.7 and 144 min, while ureteral ligation resulted in no significant change. Comparison of the level of LA-PF4/beta TG antigen and of creatinine in aorta and in renal vein showed 25%-30% extraction of these compounds by the kidney. Less than 0.1% of the total LA-PF4 antigen injected was recovered in the urine of control rats. In contrast to these results, the clearance of PF4 was not affected by nephrectomy.

IN CONCLUSION

(1) functional renal tissue is necessary for normal clearance of LA-PF4/beta TG, but renal excretion does not play a major role in its elimination suggesting that the protein is catabolized by the kidney; and (2) catabolic clearance of PF4 does not depend on functioning kidney tissue.

In vivo release and turnover of secreted platelet antiheparin proteins in rhesus monkey (Macaca mulatta)

Human and rhesus monkey platelets secrete at least two antiheparin proteins: platelet factor 4 (PF4) and low affinity platelet factor 4 (LA-PF4). Neither of these proteins showed species-related antigenic differences. As determined by radioimmunoassay, the levels of PF4 and LA-PF4 antigen per 10(9) monkey platelets amounted to 10.7 and 20.3 microgram, respectively. One milliliter of monkey plasma prepared from blood collected into an anticoagulant composed of EDTA, prostaglandin E1, and theophylline solution contained 22.4 ng LA-PF4 and 8.0 ng PF4. Concentrations of these two platelet-specific proteins in monkeys closely resembled levels found in human platelets and plasma. Infusion of prostacyclin (PGI2) (100 or 300 ng/kg/min) into monkeys for 15 min resulted in a significant decrease of plasma levels of LA-PF4 antigen and of PF4 by 40%--60% (p < 0.0001). This decrease was related to the inhibitory effect of PGI2 on the secretion of platelets stimulated by a catheter or by venipuncture. Longer infusion of PGI2 did not produce further significant change. The supernate obtained after aggregation of human platelets stimulated by thrombin was injected into monkeys receiving PGI2 infusion. The disappearance of LA-PF4 antigen in monkey plasma followed a biphasic exponential curve with half-lives for the fast and slow components of 8.4 and 63 min. PF4 disappeared faster but followed the same pattern (half-lives for the fast and slow component of 2.1 and 70 min). Analysis of the experimental data suggests that the low levels of secreted platelet proteins in monkey plasma are related to their minimal in vivo release and to their rapid clearance.

Secreted platelet proteins with antiheparin and mitogenic activities in chronic renal failure

The levels of secreted platelet antigen (LA-PF4/beta TG) were measured by radioimmunoassay in samples of PPP obtained from human blood collected on EDTA and inhibitors of platelet release reaction. These levels in plasma of 17 normal individuals, 18 nondialyzed patients with chronic renal failure, and nine patients on hemodialysis were 31.9 +/- 2.8 ng/ml, 135.1 +/- 21.4, and 291.8 +/- 26.3, respectively. No significant differences were observed in platelet counts and in the levels of this antigen in PRP of these three groups of individuals. The levels of PF4 in PPP of eight normal individuals and in plasma of seven patients with chronic renal failure were 7.41 +/- 0.67 and 7.53 +/- 1.11 ng/ml, respectively. During processing of blood samples in the absence of platelet release inhibitors, platelets of patients with chronic renal failure released less LA-PF4/beta TG antigen than did normal platelets. The mean levels of LA-PF4/beta TG antigen excreted in urine of six normal individuals and 10 patients with chronic renal failure were 57.75 and 1461.5 ng/100 mg of creatinine per day, respectively. After 3 hr hemodialysis, LA-PF4/beta TG antigen levels in PPP increased from 291.8 +/- 26.3 ng/ml to 505.3 +/- 87.3. By contrast, this antigen in three patients with successful kidney transplants rapidly returned to levels close to normal following graft function. Immunoreactive material from pooled urine of patients with chronic renal failure was isolated by isoelectric focusing. This material focused at pH 10.0 to 10.8 and induced DNA biosynthesis in 3(3 swiss cells, indicating its similarity to PBP. It is proposed that elevation of LA-PF4/beta TG antigen observed in plasma of patients with chronic renal failure resulted from the impaired handling of this protein by the kidney.

Anti-Platelet and Vasodilatory Action of Prostacyclin /PGI2/ in Healthy Men and in Patients with Peripheral Artery Disease

Intravenous infusion of PGI2/2-20 ng/kg/min/ into 10 healthy men caused vasodilatation of skin vessels, moderate decrease in blood pressure, suppression of platelet aggregability to ADP, dispersion of circulating platelet aggregates, but no distinct changes in plasma and fibrinolytic clotting factors. These results prompted us to treat with PGI2, six patients with far-advanced arteriosclerosis obliterans. A cooled solution of PGI2/5 ng/kg/min/ in alkaline buffer was administered for 72-96 hrs into femoral artery, leading to warmness and rubor of extremity, inhibition of platelet aggregation, and increase in blood flow in peripheral muscles and skin as measured with radioactive xenon. The clinical results were very good as manifested by relieve of pain, healing of chronic ulcers and resolution of deep necrosis. PGI2 due to its strong anti-platelet and vasodilatory properties seems a promising agent in therapy of peripheral artery disease.

Serum cobalt-activated acylase and gamma-glutamyl transpeptidase activities in toxic hepatitis

Marked activity of cobalt-activated acylase was found in the sera of 33 of 37 patients with acute toxic hepatitis due to poisoning with either amanita mushrooms or chemicals. The activity of the enzyme showed a positive correlation with that of serum transaminases, reached the highest levels on the patient's admission to hospital and within a few days fell rapidly to undetectable levels. Slight acylase activity was observed in the majority of patients intoxicated with drugs or carbon monoxide but was not seen in sera of those poisoned with non-amanita mushrooms who showed no signs of liver injury. Unlike acylase, the serum activity of gamma-glutamyl transpeptidase remained unchanged over the first days of acute toxic hepatitis. The determination of serum cobalt-activated acylase might be of value in the diagnosis of acute liver injury.