Reciprocal translocation t(12;13)(p13;q14) in acute nonlymphoblastic leukemia: report and cytogenetic analysis of two cases

Two cases of acute nonlymphoblastic leukemia with a reciprocal translocation t(12;13)(p13;q14) are described. Both patients were male adults with a diagnosis of M0 FAB type. Beside standard cytogenetic analysis, we applied fluorescence in situ hybridization (FISH) in order to investigate the position of the RB gene with respect to the breakpoint at 13q14. Our results showed that the RB gene was proximal to the breakpoint, but, apparently, not split in either case.

[Recovery time from myocardial ischemia induced by exercise test: correlation with duration of ischemia during the test and with the extent of coronary disease]

BACKGROUND

Aim of this study was to evaluate the factors affecting the duration of the recovery time (RT) after a positive exercise stress test and to define its relationship with the extent of coronary artery disease (CAD).

METHODS

We studied 109 consecutive patients with a positive exercise test and proven coronary disease.

RESULTS

RT was neither related to the severity of CAD, nor to exercise duration, rate-pressure product at the end of the exercise and maximum ST segment depression. A significant linear relationship was found between RT and the time of ischemia during exercise (IT) (r = 0.66, p < .001). This relationship was analyzed separately in patients (pts) with advanced (Group I) and in pts with less severe CAD (Group II). The regression line of the data showed a similar slope but a higher y-axis intercept in Group I than in Group II (p < .05). The RT/IT ratio was in fact significantly higher in Group I than in Group II (3.0 +/- 1.3 vs 1.7 +/- 0.7, p < .0001). Discriminant analysis was performed to predict the presence of advanced CAD: using the RT/IT ratio instead of RT correct classification rate of the model increased from 81.4 to 86.7%, predictive accuracy from 73.7 to 85.3% and true negative rate from 85.3 to 87.4%.

CONCLUSIONS

These results suggest that the normalization of the recovery time by time of ischemia during the test provides a simple and useful index for the prediction of the extent of coronary artery disease.

Acute promyelocytic leukemia: morphological aspects

Among AML with maturation, acute promyelocytic leukemia (APL) represents a distinct subtype which accounts for 5-10% of all the FAB variants. APL may be recognized by different cytological pictures: (i) Hypergranular APL, the most typical form, showing promyelocytes with cytoplasm packed with purple granules. Most of the primary granules may be incorporated into Auer rods, sometimes stacked in bundles of faggots. (ii) Microgranular APL, characterized by fine dustlike granulation in the cytoplasm; some promyelocytes may even appear agranular by light microscopy. Most of the cells show bilobed or folded nuclei, a picture which may simulate that of acute myelomonocytic leukemia. (iii) Hyperbasophilic form, characterized by cells with high N/C ratio, and strongly basophilic cytoplasm with either sparse or no granules. Conspicuous cytoplasmatic budding is usually present, recalling the feature of micromegakaryocytes. Strong positivity for myeloperoxidase, Sudan black B and chloroacetate esterase represents the typical cytochemical pattern of M3; usually a weaker reactivity may be observed in M3v. However, sometimes a degree of cytochemical heterogeneity of APL cells may be observed, as suggested by cases displaying a strong sodium fluoride-sensitive non-specific esterase reaction. Recently a distinct entity associated with basophilic differentiation has been described. Differential diagnosis of this form with M2-baso subtype and with cases of MDS or AML with basophilia (M2, M4 with t(6;9) translocation) may be obtained by the use of cytochemistry, cytogenetic investigations, and electron microscopy.

Association of increased fibrin turnover and defective fibrinolytic capacity with leg atherosclerosis. The PLAT Group

Patients with peripheral arterial disease have a high risk of death from cardiovascular events. As defective fibrinolysis associated with leg atherosclerosis has been suggested as a predisposing factor, we sought a relation among decreased fibrinolysis, the presence of leg atherosclerosis and the incidence of thrombotic events in a case-control study nested in the PLAT. Fifty-eight patients with coronary and/or cerebral atherothrombotic disease, free of leg atherosclerosis at Doppler examination, were compared with 50 atherosclerotic patients with leg involvement. High D-dimer (153.0 vs 81.3 ng/ml, p < 0.001) and tPA antigen before venous stasis (14.4 vs 11.8 ng/ml, p < 0.03), and low tPA antigen (6.7 vs 15.6 ng/ml, p < 0.01) and fibrinolytic activity released after venous stasis (fibrinolytic capacity: 113.2 vs 281.4 mm2, p < 0.001) were found in patients with leg atherosclerosis. D-dimer and fibrinolytic capacity, in addition to age, were selected by stepwise discriminant analysis as characterizing patients with leg atherosclerosis. Moreover, higher D-dimer and tPA inhibitor characterized patients with leg atherosclerosis who subsequently experienced thrombotic events. These findings constitute evidence of high fibrin turnover and impaired fibrinolytic potential in patients with leg atherosclerosis. Thus impaired fibrinolysis may contribute to the prothrombotic state in these patients.

Haemodynamic effects of glyceryl trinitrate during continuous 24 hour infusion in patients with heart failure

OBJECTIVE

To investigate whether the susceptibility to tolerance to glyceryl trinitrate is similar in different vascular beds in patients with chronic heart failure.

PATIENTS

Twenty patients with heart failure underwent a continuous infusion of glyceryl trinitrate over 24 hours followed by administration of N-acetylcysteine (5 g intravenously) in a bolus.

MAIN OUTCOME MEASURES

Haemodynamic measurements under control conditions, at peak titration of glyceryl trinitrate at 24 hours, and after N-acetylcysteine; plasma renin activity and packed cell volume.

RESULTS

After 24 hours of infusion the acute reduction in right atrial pressure had largely waned, while pulmonary vascular resistance remained improved and systemic resistance, which was not reduced at peak titration, significantly decreased with respect to control conditions. The effects of N-acetylcysteine and hormonal responses were different in patients who did and did not develop tolerance to glyceryl trinitrate.

CONCLUSIONS

The haemodynamic profile of glyceryl trinitrate changed substantially during the study from a predominantly venodilator action at peak titration to a predominantly arteriolar dilatation after 24 hours of infusion. The different effects of N-acetylcysteine and the different hormonal responses confirm the multifactorial pathogenesis of tolerance to glyceryl trinitrate.

Evaluation of two buflomedil tablet formulations in patients with atherosclerotic disease

The bioequivalence of a 600-mg methocel tablet containing buflomedil hydrochloride in sustained-release form was determined relative to a 300-mg CAP/carbovax-coated tablet of buflomedil hydrochloride in immediate-release form. The tablets were given to 20 patients in a double-blind placebo-controlled clinical study with cross-over between the administration plans. The 300-mg tablets were given b.i.d., at 8 a.m. and 8 p.m. while the 600-mg tablets were taken once a day at 8 a.m. (+placebo at 8 p.m.). Plasma samples were collected at appropriate times up to 24 h after administration and were analyzed for buflomedil with a validated high-performance liquid chromatographic procedure. Results showed an overall significant mean difference in absorption rate between the two formulations. The mean tmax (5.5 +/- 3.5 h) for the 600-mg tablet was longer (P < 0.001) than the tmax value (1.8 +/- 0.8 h) seen after administration of the first 300-mg tablet. Analysis of AUC(O-infinity) values indicated that the sustained-release preparation (32.1 +/- 20.7 micrograms/ml h) was not significantly different from the 300-mg tablet b.i.d. (28.7 +/- 16.0 micrograms/ml h). Furthermore, it was seen that single administration of a 600-mg sustained-release tablet of buflomedil hydrochloride delivered the same amount of total drug as a 300-mg tablet given twice a day.

[Coronary vasomotor response to acetylcholine correlates with plasma levels of cyclosporin and triglycerides in patients with heart transplantation]

BACKGROUND

Vasoconstriction of normal coronary arteries has been reported after intracoronary (i.c.) administration of acetylcholine (Ach) in cardiac transplant patients and has been related to early endothelial disfunction; the clinical correlates of this response are still unknown.

METHODS

We infused graded i.c. concentrations of Ach in 32 pts with angiographically smooth coronary arteries 1 to 3 years after heart transplantation. Changes in diameters of the proximal and middle segments of the left anterior descending coronary artery were measured by quantitative coronary angiography (automatic edge detection).

RESULTS

The response to Ach ranged from +44% to -58%; at linear regression analysis it was significantly related to the plasma levels of cyclosporine (r = -0.39, p < .05) and triglycerides (r = -0.42, p < .02) but not to vessel diameter, recipient and donor age, time after transplantation, hypertension, cholesterol levels, number of acute rejection episodes and previous cytomegalovirus infections.

CONCLUSIONS

In heart transplant pts with angiographically normal coronary arteries i.c. Ach may reveal endothelial disfunction which is associated with high cyclosporine and triglycerides plasma levels. Whether this response may predict an earlier development of coronary disease remains to be elucidated.

[Different susceptibilities to the development of nitroglycerin tolerance in the human peripheral venous and arterial circulations]

Aim of the study was to assess the relative susceptibility to the development of nitroglycerin tolerance in the arterial and venous circulation in man and to evaluate the interactions between nitroglycerin and N-acetylcysteine. Twenty patients with coronary artery disease underwent a continuous 24-h nitroglycerin infusion followed by a bolus administration of N-acetylcysteine. Forearm blood flow (ml/100 ml/min) and venous volume (ml/100 ml) were measured by strain gauge plethysmography under control conditions, at the end of nitroglycerin titration, after 24 h of infusion and after N-acetylcysteine; vascular resistance was calculated as mean cuff blood pressure/flow. After 24 h of nitroglycerin infusion, the initial increase in venous volume was reduced by 48% (p < 0.01), while the acute effects on vascular resistance were not attenuated in the whole group. N-acetylcysteine restored nitroglycerin venodilator effects in all 10 patients who developed venous tolerance but did not change significantly vascular resistance in 5 patients in whom attenuation of the arterial effects was observed during the infusion period. In conclusion, the results indicate that the susceptibility to the development of nitrate tolerance in man is higher in the venous than in the arterial circulation and that the sulphydryl group donor N-acetylcysteine is more effective in reversing nitroglycerin tolerance in the venous than in the arterial circulation.

Assessment of left ventricular function by isometric handgrip exercise after thrombolysis in patients with refractory unstable angina

The handgrip test has been proposed for the evaluation of the hemodynamic reserve in patients with coronary artery disease and to quantitate the impairment of left ventricular (LV) function. The present study was designed to evaluate the effect of thrombolytic therapy in patients with refractory unstable angina in order to test the hypothesis that a reduction in intracoronary thrombosis could ameliorate their hemodynamic response to the handgrip test. During left heart catheterization, 20 patients with refractory unstable angina of recent onset performed a handgrip test before (HG1) and 24-72 hours after (HG2) being randomized to receive recombinant tissue-type plasminogen activator or placebo, according to a double-blind parallel group design. HG1 induced an increase in heart rate (p < 0.001), in systolic pressure (p < 0.001), and a reduction in ejection fraction (p < 0.05). Changes in LV end-diastolic pressure during baseline handgrip were highly different in individual patients, resulting in a trend toward an increase. Similarly, a different individual response was observed in the behavior of the isovolumetric and relaxation indices. In comparison with HG1, no difference was detected during HG2 in the 2 treatment groups with respect to changes in LV volumes, ejection fraction, LV systolic and diastolic pressures, +dP/dt, (dP/dt)/P, -dP/dt, and tau index. In patients with refractory unstable angina of recent onset, the handgrip test performed before and after thrombolysis did not prove to be useful in assessing directional changes of LV performance, mainly because of the different individual response to the baseline handgrip test.

[K-channel activators and cardioprotection]

The hemodynamic effects of K-channel openers suggest that these drugs should be beneficial in the management of hypertension and angina. Many experimental data have also shown that K-channel openers exert effective cardioprotection, decreasing the deleterious consequences of myocardial ischemia and limiting the damage induced by reperfusion. The mechanism of myocardial protection during ischemia is still unclear, even though there are experimental results that suggest that K-channel openers may act in the same way as preconditioning. The reduction of Ca-overload and the inhibitory effect on oxidative damage are possible explanations for the myocardial protection during reperfusion.

[Coronary angioplasty in unstable angina]

Percutaneous transluminal coronary angioplasty is now largely applied either to stable or unstable patients suffering from angina pectoris. The procedural success rate and the incidence of acute complications are now comparable in the 2 population of patients. Very recent data have also shown that there is no difference in restenosis between patients with stable or unstable angina. Therefore, by now, in such unstable coronary syndromes the choice of surgical therapy is mainly determined by the presence of multivessel disease or by depressed left ventricular function. However, the possibility to obtain a complete revascularization by angioplasty or to stabilize the patients treating only the "culprit" vessel, may increase the number of unstable patients shifting from surgery to angioplasty.

[The evaluation of intracoronary stents by intravascular echography]

BACKGROUND

Intravascular ultrasound (IVUS) provides high resolution of vessel wall pathoanatomy, and because of the highly reflective nature of stent surfaces, can evaluate alterations in stent geometry.

METHODS

This study was performed to assess, by IVUS stent, expansion patterns in patients undergoing implantation of metallic coronary stents, and the mechanisms of restenosis in those patients. Twenty-five patients were studied: 9 pts acutely and 16 pts at routine follow-up 5-8 months after Palmaz-Schatz stent placement. The images recorded by IVUS (25 Mhz 3.9F catheter Intertherapy Inc. California) were quantitatively analyzed for: luminal diameter (LD), luminal cross-sectional area (LA), cross-sectional diameter (SD) and area (SA), comprised by the stent struts. We used quantitative coronary angiography (QCA) (Image Comm System) to measure lumen diameter (LD) and luminal cross-sectional area (LA) in patients in whom IVUS was not performed at the moment of stent placement. These values were considered reference values of LD and LA of the stent at follow-up.

RESULTS

During follow-up, patients showed a reduction of vessel lumen LD (2.09 +/- 0.17 mm) measured by IVUS, versus baseline LD (2.87 +/- 0.39 mm) measured by QCA. SD (2.76 +/- 0.31 mm) and SA (6.30 +/- 1.24 mm2) were unchanged in comparison with LD (2.87 +/- 0.39 mm) and LA (6.47 +/- 1.77 mm2) measured by QCA at the time of stent implantation.

CONCLUSIONS

These data suggest that the mechanism of restenosis is due to intimal proliferation rather than stent collapse.

Cytotoxic activity and mechanism of action of 5-Aza-2'-deoxycytidine in human CML cells

We investigated the cytotoxic activity and some aspects of the mode of action of 5-aza-2'-deoxycytidine (Aza-dC) in 21 primary cultures of leukemic cells freshly obtained from patients with chronic myeloid leukemia (CML) in blast crisis. The cytotoxic potency of Aza-dC was comparable or even greater than that of 1-beta-D-arabinofuranosylcytosine (Ara-C) in most cases, suggesting that this drug has potential in the therapy of blast crisis of CML. Drug incorporation into DNA was evaluated by exposing leukemic cells simultaneously to 3H-Aza-dC at the concentration of 0.1 micrograms/ml and 14C-thymidine (TdR) used as internal standard. Incorporation of Aza-dC into DNA was detectable in all cases. In 17 samples we evaluated the DNA integrity of leukemic cells exposed to Aza-dC using alkaline elution techniques. The drug caused a detectable amount of DNA alkali labile sites (ALS). DNA-ALS increased in cells exposed to Aza-dC concentrations from 0.1 to 1 microgram/ml but did not further increase at 10 micrograms/ml. A plateau in the levels of DNA-ALS was also seen in human K562 cells exposed to increasing concentrations of Aza-dC from 5 to 10 micrograms/ml, whereas in these cells Aza-dC incorporation into DNA increased with increasing Aza-dC concentrations. Therefore, DNA-ALS caused by Aza-dC are not simply the result of the chemical decomposition of azacytosine molecules incorporated into DNA, but are presumably the result of a saturable DNA repair mechanism (e.g., glycosylases) leading to formation of the apyrimidinic sites.

Increased fibrin turnover and high PAI-1 activity as predictors of ischemic events in atherosclerotic patients. A case-control study. The PLAT Group

A case-control comparison within the framework of the prospective, multidisciplinary PLAT Study was performed to assess whether altered baseline fibrinolytic variables were associated with an elevated risk of ischemic thrombotic events in patients with documented coronary, cerebral, and/or peripheral atherosclerotic disease. Fibrinogen, D-dimer, tissue plasminogen activator (t-PA) antigen, and fibrinolytic activity before and after venous stasis (delta = difference between the two values), t-PA inhibitor, and lipid levels in 60 atherosclerotic patients with a thrombotic event during the first year of follow-up were compared with those in 94 atherosclerotic patients without such events, who were matched for age, sex, and diagnosis at enrollment. Events were associated with a higher release of delta t-PA antigen (P = .047), higher D-dimer (P = .024), and higher t-PA inhibitor (P = .001) levels. delta Fibrinolytic activity was correlated inversely with t-PA inhibitor (P < .01) and triglycerides (P < .05). D-Dimer was also correlated with systolic blood pressure (P < .01). Atherosclerotic patients at higher risk of thrombotic ischemic events are characterized by increased fibrin turnover and impaired fibrinolytic activity due to high t-PA inhibitor levels. This hemostatic disequilibrium may participate with conventional risk factors such as elevated triglyceride levels and systolic blood pressure in the multifactorial mechanism of ischemic sequelae in patients with preexisting vascular atherothrombotic disease.

Coronary thrombosis in non-cardiac death

BACKGROUND

Coronary thrombosis is the major cause of acute myocardial ischaemia but can be, albeit rarely, clinically silent. We investigated a series of autopsy hearts from hospitalized patients who died from non-cardiac causes, to detect and study coronary thrombosis.

METHODS

The series consisted of 132 autopsy cases (81 men and 51 women, age range 32-39 years, mean 63 +/- 14), in whom cause of death was confirmed as extracardiac. Major epicardial coronary arteries were isolated from the hearts and routinely processed for histopathological study. We evaluated the presence of coronary atherosclerosis and thrombosis. Plaque size was histologically graded with low magnification lenses.

RESULTS

Coronary atherosclerosis, which was found in 110 hearts, caused critical stenosis or occlusion of at least one major vessel in 55 (41.6%) cases. Coronary thrombosis was found in 10 vessels from nine different hearts. One coronary tree presented two thrombi in two different vessels. Thrombi were mural in all but one vessel. We did not observe either deep sub-thrombotic ulceration or atheromatous material mixed with thrombus. Deep thrombus layers often presented organizing features. There was no correlation between thrombosis and degree of vessel stenosis, which was only mildly increased by thrombus. Plaque rupture without thrombus was found in five coronary arteries of five different cases.

CONCLUSIONS

Coronary thrombus may overlay the intima of a diseased vessel independently of plaque type and severity. Moreover, thrombosis is more frequent than expected, although it is rare when compared with the spread of coronary atherosclerosis. It may represent a plaque progression mechanism in the natural history of coronary atherosclerosis.

Increased expression of neutrophil and monocyte adhesion molecules in unstable coronary artery disease

BACKGROUND

A rapid increase in leukocyte adhesion to endothelial cells is one of the first events in the acute inflammatory response and in the pathogenesis of vascular diseases. A subgroup of cell surface glycoproteins (the CD11/CD18 complex) play a major role in the leukocyte adhesion process; in particular, the CD11b/CD18 receptor can be upregulated severalfold in response to chemotactic factors. The purpose of this study was to assess whether upmodulation of granulocyte and monocyte CD11b/CD18 receptors takes place during the passage of blood through the coronary tree of patients with clinical manifestations of ischemic heart disease.

METHODS AND RESULTS

Thirty-nine patients who underwent diagnostic coronary arteriography were studied. Group 1 (15 patients) had a clinical diagnosis of unstable angina, group 2 (14 patients) had stable exertional angina, and group 3 (10 patients) had atypical chest pain. Simultaneous sampling from the coronary sinus and aorta was obtained before coronary arteriography. Cell surface receptors were detected by direct immunofluorescence evaluated by flow cytofluorimetry using monoclonal antibodies tagged with fluorescent markers. Leukocytes were stained in unseparated blood to avoid in vitro manipulation that could activate phagocytes. Group 1 and 2 patients had significant coronary artery disease (> 50% coronary narrowing in at least one major coronary vessel), whereas group 3 patients had normal coronary arteries. In group 1, granulocytes and monocytes showed a significantly higher expression of the CD11b/CD18 adhesion receptor in the coronary sinus than in the aorta (both P < .01), whereas no difference in CD11b/CD18 expression was seen in groups 2 and 3.

CONCLUSIONS

Patients with unstable angina have an increased expression of granulocyte and monocyte CD11b/CD18 adhesion receptors, indicating that an inflammatory reaction takes place within their coronary tree. Activation of these leukocytes may induce coronary vasoconstriction, favor thrombotic processes, and further activate platelets, thus having potential implications on the pathogenesis of unstable coronary artery disease.

Morphologic changes induced by acetylcholine infusion in normal and atherosclerotic coronary arteries

Low doses of acetylcholine induce "endothelium-dependent" dilatation in normal coronary arteries and constriction of diseased vessels. This study investigated morphologic changes induced by perfusion of normal and diseased coronary arteries with low and high doses of acetylcholine. Vessels were excised from a series of beating hearts explanted at transplantation for idiopathic dilated cardiomyopathy and coronary artery disease. Coronary arteries from other explanted hearts, perfused with saline solution under similar conditions were taken as controls. Samples were studied using conventional histopathologic and immunohistochemical methods. Coronary arteries were grouped according to presence or absence of histologically detectable structural modifications of any type and extent. Low doses of acetylcholine induced changes in all but 1 structurally diseased coronary artery, whereas no change was induced in any but 1 histologically normal coronary artery. High doses of acetylcholine induced contraction changes in both normal and diseased vessels. Changes observed in the wall of the contracted vessels were: (1) endothelial cell contraction with protruding nuclei and detachment of their intercellular junctions with exposure of subjacent collagen to flow, (2) contraction of plaque smooth muscle cells, (3) formation of cushions protruding into vessel lumens causing blunt microchannels. Contraction in both intimal and plaque cells occurred even in diseased vessel segments with intimal denudation. These effects seemed to be dose-dependent in structurally normal vessels because low doses of acetylcholine did not produce any morphologically detectable changes in histologically normal coronary arteries, while low doses of acetylcholine induced similar reactions in vessels affected by both atherosclerosis and subintimal fibrocellular thickening.

Influence of elastic recoil on restenosis after successful coronary angioplasty in unstable angina pectoris

The elastic behavior of the dilated coronary vessel has been reported to affect the immediate results of coronary angioplasty. To determine whether elastic recoil may also influence the long-term restenosis process, 98 consecutive patients with unstable angina and 1-vessel disease were studied. An automated coronary quantitative program was used for the assessment of balloon and coronary luminal diameters. Elastic recoil was defined as the percent reduction between minimal balloon diameter at the highest inflation pressure and minimal lesion diameter immediately after coronary angioplasty. Follow-up coronary arteriography was performed 8 to 12 months after the procedure in all patients. The mean elastic recoil averaged 17.7 +/- 16% and was correlated to the degree of residual stenosis immediately after coronary angioplasty (r = 0.64; p < 0.001). Restenosis, defined as > 50% diameter stenosis at follow-up, developed in 53 patients (54%). There was no correlation between the degree of elastic recoil and the changes in minimal lesion diameter observed during follow-up, whereas a positive correlation between the amount of elastic recoil and the incidence of restenosis was documented (r = 0.84; p < 0.05). Thus, the elastic properties of the dilated vessel do not influence the active process of restenosis. However, because elastic recoil negatively influences the initial results of angioplasty, it is more likely that further reductions in lumen diameter during follow-up can reach a threshold of obstruction considered critical for a binary definition of restenosis.

Evidence of a hypercoagulable state in patients with acute lymphoblastic leukemia treated with low dose of E. coli L-asparaginase: a GIMEMA study

Blood coagulation abnormalities induced by administration of E. coli L-asparaginase were investigated in 25 patients with acute lymphoblastic leukemia treated according to the GIMEMA ALL 0288 trial. Dosage of L-asparaginase was relatively low (6,000 U/m2/day for 7 days total dose 42,000 U/m2) as compared to the conventional dosages (120,000-140,000 U/m2 over 10-14 days). A significant decrease in fibronogen, plasminogen, alpha2-antiplasmin and antithrombin III was observed from day IV of L-asparaginase and it was maximum on day VIII, with return to the baseline levels on day XV. Protein C levels had only a borderline reduction, while no modification of protein S or factor VII was observed. Two of the patients investigated developed thrombosis. The presence of a prothrombotic state induced even by this low dosage of E. coli L-asparaginase was suggested by a significant increase of sensitive markers of hypercoagulability such as fibrinopeptide A, thrombin-antithrombin complexes, and prothrombin fragment F1 + 2.

Different susceptibility to the development of nitroglycerin tolerance in the arterial and venous circulation in humans. Effects of N-acetylcysteine administration

BACKGROUND

Tolerance to the effects of organic nitrates develops rapidly during continuous exposure to these drugs; its main mechanism seems to be an intracellular sulfhydryl group depletion. However, the relative susceptibility to the development of nitroglycerin tolerance of the arterial or venous circulation in humans is still a matter of dispute.

METHODS AND RESULTS

Twenty patients with coronary artery disease underwent a continuous 24-hour nitroglycerin infusion followed by a bolus administration of N-acetylcysteine. Forearm blood flow (ml/100 ml/min) and venous volume (ml/100 ml) were measured by strain gauge plethysmography under control conditions, at the end of nitroglycerin titration, after 24-hour infusion, and after N-acetylcysteine; vascular resistance was calculated as mean cuff blood pressure divided by flow. After 24 hours of nitroglycerin infusion, the initial increase in venous volume was reduced 48% (p less than 0.01), whereas the acute effects on vascular resistance were not attenuated in the whole group. N-Acetylcysteine completely restored nitroglycerin venodilator effects in all 10 patients in whom attenuation of the venous effects was observed during the infusion period.

CONCLUSIONS

The data indicate that the susceptibility to the development of nitrate tolerance in humans is higher in the venous than in the arterial circulation, and that the sulfhydryl group donor N-acetylcysteine is extremely effective in reversing nitroglycerin tolerance in the venous circulation in humans.

The PLAT Study: hemostatic function in relation to atherothrombotic ischemic events in vascular disease patients. Principal results. PLAT Study Group. Progetto Lombardo Atero-Trombosi (PLAT) Study Group

The Progetto Lombardo Atero-Trombosi (PLAT) Study was a prospective, multicenter, multidisciplinary study of the association among hemostatic variables, conventional risk factors, and atherothrombotic events in four groups of patients with preexisting vascular ischemic disease (335 myocardial infarction survivors, 123 patients with stable angina pectoris, 160 with transient ischemic attacks, and 335 with peripheral vascular disease). In the myocardial infarction group, univariate analysis showed that atherothrombotic events were associated with high fibrinogen (p = 0.001), factor VIII:C (p less than 0.001), and von Willebrand factor antigen (vWF:Ag) (p = 0.004) levels and with low high density lipoprotein cholesterol (p = 0.043), factor VII (p = 0.019), and protein C (p = 0.044) levels; multivariate analysis produced associations with high fibrinogen and factor VIII:C levels and low protein C levels. By both univariate and multivariate analysis, events in the angina pectoris group were associated with high vWF:Ag (p = 0.026) and leukocyte (p = 0.033) levels and the presence of carotid arterial stenosis (p = 0.063); associations with high leukocyte (p = 0.037) and factor VIII:C (p = 0.186) levels, family history (p = 0.031), and diabetes (p = 0.061) were also found in the group with transient ischemic attacks. In those with peripheral vascular disease, events were associated with Fontaine stage greater than or equal to IIB (p = 0.024), high factor VIII:C levels (p = 0.073), and low protein C (p = 0.028), fibrinogen (p = 0.030), antithrombin III (p = 0.054), and factor VII (p = 0.057) levels by univariate analysis and with Fontaine stage and low fibrinogen levels by multivariate analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Dobutamine-induced ST segment elevation in a patient with angina at rest and critical coronary lesions

A case of dobutamine-induced ST-segment elevation in a patient with angina at rest and severe two-vessel disease is described. Coronary angiography performed during the ischaemic episode showed patency of coronary arteries; ST-segment elevation and chest pain regressed after propranolol administration. This case suggests that in the presence of severe coronary lesions dobutamine may produce transmural myocardial ischaemia by increasing myocardial oxygen demand and inducing myocardial blood flow maldistribution.