Effect of High Dose Statin Pretreatment on Endothelial Progenitor Cells After Percutaneous Coronary Intervention (HIPOCRATES Study).

BACKGROUND: Pretreatment with high-dose statins given before percutaneous coronary intervention (PCI) has been shown to have beneficial effects, in particular by reducing peri-procedural myocardial infarction. The mechanism of these lipid-independent beneficial statin effects is unclear. Circulating endothelial progenitor cells (EPCs) have an important role in the process of vascular repair, by promoting re-endothelization following injury. We hypothesized that statins can limit the extent of endothelial injury induced by PCI and promote re-endothelization by a positive effect on EPCs. We, therefore, aimed to examine the effect of high-dose statins given prior to PCI on EPCs profile. METHODS: Included were patients, either statin naïve or treated chronically with low-dose statins, with stable or unstable angina who underwent PCI. Patients were randomized to receive either high-dose atorvastatin (80 mg the day before PCI and 40 mg 2-4 h before PCI) or low- dose statin. EPCs profile was examined before PCI and 24 h after it. Circulating EPCs levels were assessed by flow cytometry as the proportion of peripheral mononuclear cells co-expressing VEGFR-2+ CD133+ and VEGFR-2+ CD34+. The capacity of the cells to form colony forming units (CFUs) was quantified after 7 days of culture. RESULTS: Twenty three patients (mean age 61.4 ± 7.4 years, 87.0% men) were included in the study, of which 12 received high-dose atorvastatin prior to PCI. The mean number of EPC-CFUs before PCI was higher in patients treated with high-dose atorvastatin vs. low-dose statins (165.8 ± 58.8 vs. 111.7 ± 38.2 CFUs/plate, respectively, p < 0.001). However, 24 h after the PCI, the number of EPC-CFUs was similar (188.0 ± 85.3 vs. 192.9 ± 66.5 CFUs/plate in patients treated with high-dose atorvastatin vs. low- dose statins, respectively, p = 0.15). There were no statistical significant differences in FACS analyses between the 2 groups. CONCLUSIONS: The current study showed higher EPC- CFUs levels in patients treated with high-dose atorvastatin before PCI and a lower increment in EPC-CFUs after PCI. These findings could account for the beneficial effects of statins given prior to PCI, yet further investigation is required.

Reticulated platelets and uninhibited COX-1 and COX-2 decrease the antiplatelet effects of aspirin.

BACKGROUND: The mechanisms for the variability in antiplatelet effects of aspirin are unclear. Immature (reticulated) platelets may modulate the antiplatelet effects of aspirin through uninhibited cyclooxygenase (COX)-1 and COX-2. OBJECTIVES: To evaluate the role of reticulated platelets in the antiplatelet effects of aspirin. METHODS: Sixty healthy volunteers had platelet studies performed before and 24 h after a single 325-mg dose of aspirin. Platelet studies included light transmission aggregometry; P-selectin and integrin alpha(IIb)beta(3) expression, and serum thromboxane B(2) (TxB(2)) levels. Reticulated platelets and platelet COX-2 expression were measured using flow cytometry. RESULTS: Subjects were divided into tertiles based on the percentage of reticulated platelets in whole blood. Baseline platelet aggregation to 1 microg mL(-1) collagen, and postaspirin aggregations to 5 microm and 20 microm ADP and collagen, were greater in the upper than in the lower tertile of reticulated platelets. Stimulated P-selectin and integrin alpha(IIb)beta(3) expression were also higher in the upper tertile both before and after aspirin. Platelet COX-2 expression was detected in 12 +/- 7% (n = 10) of platelets in the upper tertile, and in 7 +/- 3% (n = 12) of platelets in the lower two tertiles (P = 0.03). Postaspirin serum TxB(2) levels were higher in the upper (5.5 +/- 4 ng mL(-1)) than in the lower tertile (3.2 +/- 2.5 ng mL(-1), P = 0.03), and decreased even further with ex vivo additional COX-1 and COX-2 inhibition. The incidence of aspirin resistance (>or= 70% platelet aggregation to 5 microm ADP) was significantly higher in the upper tertile (45%) than in the lower tertile (5%, P < 0.0001). CONCLUSIONS: Reticulated platelets are associated with diminished antiplatelet effects of aspirin and increased aspirin resistance, possibly because of increased reactivity, and uninhibited COX-1 and COX-2 activity.

Testing platelet activation with a shear-dependent platelet function test versus aggregation-based tests: relevance for monitoring long-term glycoprotein IIb/IIIa inhibition.

BACKGROUND: Tests developed to monitor glycoprotein (GP) IIb/IIIa blockade do not properly reflect platelet function in vivo and need a baseline (pretreatment) value. Because GP IIb/IIIa is essential in platelet aggregation and thrombosis under shear conditions, a flow-dependent approach to monitor its inhibition can be used. METHODS AND RESULTS: We compared a test based on flow-dependent platelet deposition, the Cone and Platelet Analyzer (CPA), with in vitro platelet aggregometry and the Rapid Platelet Function Assay (RPFA) on platelet function after GP IIb/IIIa inhibition. In vitro, increasing concentrations of abciximab (0% to 100% receptor occupancy) were tested. Ex vivo, platelet function was monitored with the CPA and with aggregometry for up to 1 week after abciximab administration. The CPA was better correlated with the percentage of free GP IIb/IIIa receptors than was aggregometry or the RPFA. Only the RPFA, when expressed as a ratio over baseline (pretreatment), was comparable to the CPA. Ex vivo, the CPA, but not aggregometry, showed prolonged platelet inhibition with gradual recovery from GP IIb/IIIa receptor blockade in the first week after abciximab administration. CONCLUSIONS: Platelet function assessment by shear-induced deposition is a reliable test to monitor a wide range of GP IIb/IIIa inhibition. Its accuracy does not require a baseline reference. The effects of GP IIb/IIIa blockade on platelet function should be examined under high shear conditions.

Blood thrombogenicity in type 2 diabetes mellitus patients is associated with glycemic control.

OBJECTIVES: This study was designed to determine whether blood thrombogenicity is related to chronic glycemic control in type 2 diabetes mellitus (T2DM). BACKGROUND: Type 2 diabetes mellitus is associated with accelerated atherosclerosis and a high rate of arterial thrombotic complications. Whether increased blood thrombogenicity is associated with glycemic control has not been properly tested. METHODS: Forty patients with T2DM with hemoglobin A1c (HbA1c) > or =7.5% were selected. Maintaining their current hypoglycemic therapies, patients were randomized into a conservative (diet modification plus placebo) or intensive (diet modification plus troglitazone) hypoglycemic regimen for three months. Blood thrombogenicity was measured at baseline and after three months with the Badimon ex vivo perfusion chamber and assessed as platelet-thrombus formation. The repeated measurements allowed every patient to be his/her own control. RESULTS: Patients in both groups (48% and 74% of the conservative and intensive groups, respectively) improved glucose control (HbA1c reduction > or =0.5%), showing a significant decrease in blood thrombogenicity. A significant positive correlation was observed between the reduction in thrombus formation and the reduction in HbA1c (r = 0.47, p < 0.01). The reduction in HbA1c achieved by both treatments was comparable. Patients without glycemic improvement showed no change in blood thrombogenicity. Improved glycemic control was the only significant predictor of a decrease in blood thrombogenicity. CONCLUSIONS: In T2DM, there is an association between improved glycemic control and blood thrombogenicity reduction. The effect of glycemic control on the thrombotic complications of T2DM patients deserves further investigation.

Administration of abciximab to patients receiving tirofiban or eptifibatide: effect on platelet function.

OBJECTIVES: The goal of this study was to evaluate platelet function and to preliminarily assess the clinical safety of sequential treatment with tirofiban or eptifibatide followed by abciximab in patients undergoing percutaneous coronary intervention (PCI). BACKGROUND: An increasing number of acute coronary syndrome (ACS) patients are treated early with tirofiban or eptifibatide. Some later require PCI and may benefit from switching to abciximab, for which long-term benefits have been reported. METHODS: Fifty ACS patients planned for PCI were enrolled. Twenty-five patients received tirofiban followed by abciximab. Ten patients received eptifibatide followed by abciximab. Fifteen patients received only abciximab. All patients had blood samples drawn six times during the therapeutic course. Platelet function was evaluated by ADP- and TRAP-induced aggregation, flow cytometry analysis of fibrinogen binding and the cone and plate(let) analyzer, which tests shear rate-dependent platelet activation. RESULTS: Administered after tirofiban, abciximab caused a significant further decline in platelet function, as evidenced by all methods. Administered after eptifibatide, abciximab caused a significant further reduction in platelet function, as assessed by the cone and plate(let) analyzer and fibrinogen binding methods. The platelet inhibition achieved by the combination therapy was always greater than or equal to that achieved by abciximab alone. There were no major bleeding or severe thrombocytopenia episodes. Three of the 35 combination therapy patients and one of the 15 who received abciximab alone had minor bleeding. CONCLUSIONS: This is the first in vivo study of combination intravenous platelet glycoprotein IIb/IIIa inhibitor therapy. Administration of abciximab immediately after tirofiban or eptifibatide therapy effectively inhibits platelet function and appears to be safe.

Acute antithrombotic effect of a front-loaded regimen of clopidogrel in patients with atherosclerosis on aspirin.

There is a need for a rapid antithrombotic effect after the administration of antiplatelet drugs in the setting of acute coronary syndromes and percutaneous interventions. Clopidogrel, a new thienopyridine derivative, is an efficient antiplatelet agent. However, the standard regimen of clopidogrel (75 mg/d) requires 2 to 3 days before significant antithrombotic effects. Patients with stable arterial disease on chronic aspirin therapy (n=20) were treated with clopidogrel either with a front-loaded regimen, 300 mg the first day and 75 mg/d the next 7 days, or with a standard regimen, 75 mg/d for 8 days. Blood thrombogenicity was assessed by quantification of platelet-thrombus formation in an ex vivo perfusion chamber, by ADP-induced platelet aggregation, and by ADP-induced fibrinogen binding. At 2 hours, mean total thrombus area with the standard regimen was not significantly reduced. In contrast, at 2 hours, the mean total thrombus area with the front-loaded regimen was significantly decreased by 23.1+/-8.5% versus baseline (P<0.05). ADP-induced platelet aggregation (with 5 and 10 micromol/L) was also significantly (P<0.05) reduced with the front-loaded regimen at 2 hours, with the mean platelet aggregation being 82.2+/-4.4% and 81.8+/-4.5%, respectively, versus baseline. Similarly, flow cytometry demonstrated a significant decrease (P<0. 05) in the ADP-induced fibrinogen binding (with 0.12 and 0.6 micromol/L) at 2 hours in this front-loaded regimen group (36.1+/-2. 0% and 53.2+/-9.3%). With the standard regimen, platelet activity was not significantly reduced at 2 hours. Our data suggest that a front-loaded regimen of clopidogrel added to aspirin achieves a significant antithrombotic effect at 2 hours in patients with known atherosclerotic disease on chronic aspirin therapy. This provides a rationale for using front-loaded clopidogrel in combination with aspirin in percutaneous coronary interventions.

Distribution of serum creatine kinase activity in young healthy persons.

The normal distribution of serum creatine kinase (CK) was determined in 428 men (mean age = 21.5) and 540 women (mean age = 20.2). The bootstrap method was employed to obtain statistical parameters of CK reference range and correlations with physical activity habits, BMI, cigarette smoking and alcohol consumption. CK distribution was non-Gaussian and skewed toward the higher values; 18.9% of the men and 4.6% of the women had values above the upper reference limits defined for the commercial assay kit. The median 97.5 percentile value was 532 u/l for men and 248 u/l for women (95% confidence interval of 384-738 u/l and 184-340 u/l, respectively). A significant correlation was found only between CK and alcohol consumption in men. Myoglobin level in a representative group of subjects correlated well with CK activity for both genders. Our findings define the range of CK values in a healthy, young, heterogeneous population. We suggest that only CK levels above the determined 97.5 percentile should warrant further clinical investigation.

Creatine kinase activity decrease with short-term freezing.

Freezing of serum samples at -30 degrees C without protective agents is the simplest and least expensive method of storage in serum banks. We investigated the stability of creatine kinase (CK) in human sera after freezer storage under such conditions for 24 h (n = 30) or for 2 or 4 weeks (n = 99). CK activity was measured in fresh sera and compared to matched thawed sera after freezer storage at the designated time intervals. The enzyme's median activity decreased significantly after 24 h, 2 weeks, and 4 weeks of freezer storage by 2.6, 5.9, and 8.3%, respectively (p < 0.0001, r = 0.99). Sex or high CK initial values had no significant effect on these results. We conclude that freezer storage of serum at -30 degrees C, even for short periods, causes a steady and significant decline in CK activity. These results should be taken into consideration when analyzing CK activity in frozen sera for research or clinical purposes.

Preparing hospitals for toxicological mass casualties events.

OBJECTIVE: For most hospital staffs, treatment of chemical casualties presents an obscure and even frightening situation. We report our unique experience from hospital drills in order to improve hospital preparedness for patient management under mass casualty conditions involving hazardous chemicals. SETTING: Twenty-one major hospitals in Israel. INTERVENTIONS: A unique hospital deployment plan for the management of chemical casualties was developed, and hospitals were required to have a full chemical practice drill every 3 to 5 yrs. These drills were designed as realistically as possible, and all included the use of personal protective equipment, decontamination, and treatment of simulated patients. Twenty-five percent of these patients, simulating children and adults, required intensive care and ventilation support. Hospitals were inspected and reviewed on the quality of treatment given and the overall continuity of care as well as on their administrative performance. RESULTS: Between 1986 to 1994, 30 full chemical practice drills were conducted in 21 major hospitals. Each drill included treatment of 100 to 400 simulated patients. The lessons from the hospital drills are described and were incorporated in the proposed revised hospital deployment plan. All hospitals significantly improved their ability to respond appropriately to these incidents. CONCLUSIONS: The level of preparedness for a chemical mass casualty scenario should be established according to the existing threat and the available resources. The proposed plan can serve as a basis for hospital planning and staff training worldwide, thus facilitating optimal care in the event of an incident involving toxic chemicals. A cost-effective scale for hospital preparation levels according to the existing threat is suggested.

Hemophilus influenzae biotype III cellulitis in an adult.

The case of a patient with systemic lupus erythematosus presenting with severe leg cellulitis caused by Hemophilus influenzae non-B biotype III is reported. Skin infections caused by H. influenzae in general, and of the extremities in particular, seem to be rare in adults. This is the first reported case of cellulitis caused by H. influenzae biotype III. The infection was treated successfully with antibiotics. This case highlights the importance of blood cultures and prompt antimicrobial treatment in febrile adults with cellulitis, especially immunocompromised patients.

Exercise-induced aortic flow parameters in early postmenopausal women and middle-aged men.

OBJECTIVE: Exercise Doppler echocardiography has been recognised as an accurate method for the assessment of left ventricular function in patients with coronary artery disease. Gender differences in aortic flow parameters during exercise have not been well established. The aims of this study were to compare basal ejection Doppler indexes in healthy early postmenopausal women with those of men, and to assess the effects of both isometric and dynamic exercises on these parameters. DESIGN: Intergroup comparison between early postmenopausal women and middle-aged men. SUBJECTS: Fifteen healthy women with a mean age of 55 (SD 5) years and 15 healthy men aged 52 (SD 4) were evaluated. SETTING: Women were recruited from a menopause clinic and men from a primary cardiovascular prevention program at a cardiac rehabilitation institute. INTERVENTIONS: Isometric exercise was performed with a 2-hand bar dynamometer, and dynamic exercise with a supine ergometer. Echo Doppler examination was performed at rest and at peak isometric and dynamic exercise with a pulsed Doppler transducer. RESULTS: Both types of exercise resulted in higher values of hemodynamic parameters in the women, with most figures reaching statistical significance. Most aortic flow parameters during rest and exercise were also significantly higher in the women. CONCLUSIONS: The unexpected higher values in hemodynamic and aortic flow parameters in early postmenopausal women as compared with middle aged men may shed light on a peculiar aspect of gender differences in cardiovascular function, perhaps specific to this age group and related to menopausal transition.