Maciej Siński

Statins impair antitumor effects of rituximab by inducing conformational changes of CD20.

Background Rituximab is used in the treatment of CD20+ B cell lymphomas and other B cell lymphoproliferative disorders. Its clinical efficacy might be further improved by combinations with other drugs such as statins that inhibit cholesterol synthesis and show promising antilymphoma effects. The objective of this study was to evaluate the influence of statins on rituximab-induced killing of B cell lymphomas. Methods and Findings Complement-dependent cytotoxicity (CDC) was assessed by MTT and Alamar blue assays as well as trypan blue staining, and antibody-dependent cellular cytotoxicity (ADCC) was assessed by a 51Cr release assay. Statins were found to significantly decrease rituximab-mediated CDC and ADCC of B cell lymphoma cells. Incubation of B cell lymphoma cells with statins decreased CD20 immunostaining in flow cytometry studies but did not affect total cellular levels of CD20 as measured with RT-PCR and Western blotting. Similar effects are exerted by other cholesterol-depleting agents (methyl-β-cyclodextrin and berberine), but not filipin III, indicating that the presence of plasma membrane cholesterol and not lipid rafts is required for rituximab-mediated CDC. Immunofluorescence microscopy using double staining with monoclonal antibodies (mAbs) directed against a conformational epitope and a linear cytoplasmic epitope revealed that CD20 is present in the plasma membrane in comparable amounts in control and statin-treated cells. Atomic force microscopy and limited proteolysis indicated that statins, through cholesterol depletion, induce conformational changes in CD20 that result in impaired binding of anti-CD20 mAb. An in vivo reduction of cholesterol induced by short-term treatment of five patients with hypercholesterolemia with atorvastatin resulted in reduced anti-CD20 binding to freshly isolated B cells. Conclusions Statins were shown to interfere with both detection of CD20 and antilymphoma activity of rituximab. These studies have significant clinical implications, as impaired binding of mAbs to conformational epitopes of CD20 elicited by statins could delay diagnosis, postpone effective treatment, or impair anti-lymphoma activity of rituximab.

Cardiotoxicity of the Anticancer Therapeutic Agent Bortezomib

Recent case reports provided alarming signals that treatment with bortezomib might be associated with cardiac events. In all reported cases, patients experiencing cardiac problems were previously or concomitantly treated with other chemotherapeutics including cardiotoxic anthracyclines. Therefore, it is difficult to distinguish which components of the therapeutic regimens contribute to cardiotoxicity. Here, we addressed the influence of bortezomib on cardiac function in rats that were not treated with other drugs. Rats were treated with bortezomib at a dose of 0.2 mg/kg thrice weekly. Echocardiography, histopathology, and electron microscopy were used to evaluate cardiac function and structural changes. Respiration of the rat heart mitochondria was measured polarographically. Cell culture experiments were used to determine the influence of bortezomib on cardiomyocyte survival, contractility, Ca(2+) fluxes, induction of endoplasmic reticulum stress, and autophagy. Our findings indicate that bortezomib treatment leads to left ventricular contractile dysfunction manifested by a significant drop in left ventricle ejection fraction. Dramatic ultrastructural abnormalities of cardiomyocytes, especially within mitochondria, were accompanied by decreased ATP synthesis and decreased cardiomyocyte contractility. Monitoring of cardiac function in bortezomib-treated patients should be implemented to evaluate how frequently cardiotoxicity develops especially in patients with pre-existing cardiac conditions, as well as when using additional cardiotoxic drugs.

Tonic activity of carotid body chemoreceptors contributes to the increased sympathetic drive in essential hypertension

Carotid chemoreceptors provoke an increase in muscle sympathetic nerve activation (MSNA) in response to hypoxia; they are also tonically active during normoxic breathing. The contribution of peripheral chemoreceptors to sympathetic activation in hypertension is incompletely understood. The aim of our study was to investigate the effect of chemoreceptor deactivation on sympathetic activity in untreated patients with hypertension. A total of 12 untreated hypertensive males and 11 male controls participated in this randomized, crossover, placebo-controlled study. MSNA, systolic blood pressure(BP), diastolic BP, heart rate (HR), electrocardiogram, hemoglobin oxygen saturation (Sat%) and respiratory movements were measured during repeated 10-min periods of respiration with 100% oxygen or 21% oxygen in a blinded fashion. Compared with controls, hypertensives had higher resting MSNA (38±10 vs. 29±0.9 burst per min, P<0.05), systolic BP (150±12 vs. 124±10 mm Hg, P< 0.001) and diastolic BP (92±10 vs. 77±9 mm Hg, P<0.005). Breathing 100% oxygen caused significant decrease in MSNA in hypertensive patients (38±10 vs. 26±8 burst per min and 100±0 vs. 90±10 arbitrary units, P<0.05) and no change in controls (29±9 vs. 27±7 burst per min and 100±0 vs. 96±11 arbitrary units). BP, respiratory frequency and end tidal CO2 did not change during chemoreceptor deactivation with hyperoxia. HR decreased and Sat% increased in both the study groups. These results confirm the role of tonic chemoreceptor drive in the development of sympathetic overactivity in hypertension.

Simvastatin reduces sympathetic activity in men with hypertension and hypercholesterolemia

Beyond their hypolipidemic effect, statins reduce cardiovascular risk in hypertensive subjects via various mechanisms; one suggested mechanism is that they reduce sympathetic activity. We investigated the hypothesis that simvastatin decreased muscle sympathetic nerve activity (MSNA) in 31 hypertensive subjects with hypercholesterolemia (aged 38.7±10 years). In this randomized, placebo-controlled, double-blinded study, patients were treated with simvastatin (40 mg day−1; n=15) or placebo (n=16) for 8 weeks. Before and after treatment, we measured MSNA, blood pressure and heart rate. Baroreceptor control of the heart rate, or baroreceptor sensitivity (BRS), was computed by the sequence method, a cross-analysis of systolic blood pressure and the electrocardiogram R–R interval. Blood samples were tested for plasma levels of catecholamines, neuropeptide Y, aldosterone, endothelin and renin activity. Simvastatin significantly reduced MSNA (from 36.5±5 to 27.8±6 bursts per min, P=0.001), heart rate (from 77±6.7 to 71±6.1 beats per min, P=0.01) and both total and low-density lipoprotein cholesterol (from 249±30.6 to 184±28.3 mg dl−1, P=0.001 and from 169±30.6 to 117±31.2 mg dl−1, P=0.01, respectively). Simvastatin also improved BRS (from 10.3±4.1 to 17.1±4.3 ms per mm Hg, P=0.04). No changes were observed in systolic or diastolic blood pressures, or in plasma levels of catecholamines, neuropeptide Y, endothelin, aldosterone and renin activity. After simvastatin therapy, MSNA and BRS were inversely related (r=−0.94, P<0.05). In conclusion, we found that, in patients with hypertension and hypercholesterolemia, simvastatin reduced MSNA, and this was related to increased baroreceptor sensitivity.

Deactivation of carotid body chemoreceptors by hyperoxia decreases blood pressure in hypertensive patients

Previous studies have shown that hyperoxia-induced deactivation of carotid body chemoreceptors reduces sympathetic activity in hypertensive patients but it does not affect blood pressure. The maintenance of blood pressure can be explained by the direct, vasoconstrictive effect of hyperoxia, which offsets diminished sympathetic activity. This study compares the effect of acute hyperoxia on hemodynamic parameters between hypertensive and normotensive subjects. Twelve males with hypertension (age 39.4±2.4 years; body mass index 27.4±1.1 kg m−2) and 11 normotensive males (age 39.9±2.7 years; body mass index 25.4±0.7 kg m−2) received, via non-rebreathing mask ventilation, ambient air, followed by 100% oxygen for 20 min. The stroke volume, heart rate, cardiac output, blood pressure, total peripheral resistance, respiratory rate, baroreceptor control of heart rate and oxygen saturation were recorded continuously. Several 30 s periods were analyzed before, during and after inducing hyperoxia. At baseline, the hypertensive subject’s blood pressure was higher and their baroreflex control of heart rate was lower when compared with the normotensive control group. After the first 30 s of hyperoxia, systolic, diastolic and mean blood pressures, as well as the total peripheral resistance, decreased significantly in hypertensives but not in normotensives. After 20 min of 100% oxygen ventilation, systolic and mean blood pressures and total peripheral resistance was increased in hypertensive patients, and the cardiac output and stroke volume had decreased in both groups. The results of this study confirm that deactivation of carotid body chemoreceptors can acutely decrease blood pressure in humans.

The effect of enalapril and telmisartan on clinical and biochemical indices of sympathetic activity in hypertensive patients.

Objective. To compare the effect of ARB and ACE inhibitor on sympathetic activity in 32 hypertensives. Design and Methods. After a four-week wash-out period, patients were randomized to four weeks of therapy with enalapril or telmisrtan, with crossover to another drug for another four weeks. Blood pressure (BP), NPY, and catecholamine levels and HRV (frequency analysis) were measured during wash-out, in basal condition, and after postural stimulation test (PST). Results. Both drugs significantly reduced BP and NPY as compared to initial values, while no differences in BP and NPY between drugs were observed. Increase in NPY during PST was significantly higher in the enalapril than in the telmisartan group and during the wash-out period. No differences between enalapril and telmisartan in plasma catecholamines were observed. Telmisartan decreased low frequency/high frequency ratio as compared to initial values and enalapril values. Conclusions. Despite similar BP control, telmisartan attenuated autonomic balance more effectively than enalapril.

Automated oscillometric measurement of the ankle–brachial index in patients with coronary artery disease

Automated oscillometric ankle–brachial index (ABI) devices were designed to measure ABI in a primary-care setting to increase the peripheral artery disease (PAD) detection rate. However, ABI measurements obtained with an automated oscillometric device may differ from those obtained using a standard ultrasound Doppler method in the general population. The purpose of this study was to compare PAD detection by the Doppler method and the automated WatchBP Office ABI system in a high-risk population with coronary artery disease (CAD). Eighty consecutive patients with confirmed CAD were included. ABI was measured by automated oscillometry followed by conventional Doppler evaluation. PAD was defined as an ABI⩽0.9. Each lower extremity was analyzed separately. The Doppler method detected an ABI⩽0.9 in 56 lower extremities, whereas the automated method detected an ABI⩽0.9 in 28 lower extremities (P<0.0001). A Bland–Altman plot showed poor agreement between the two methods. The mean ABI values obtained by the automated and Doppler methods were significantly different (1.11±0.20 vs. 0.95±0.24; P<0.00001). The sensitivity of the automated ABI device in detecting an ABI⩽0.9 was 46.3% and the specificity was 98.0%. The positive and negative predictive values for diagnosing an ABI⩽0.9 using the automated oscillometric method were 92.8% and 76.9%, respectively. In conclusion, the automated WatchBP Office ABI system should be used with caution for PAD detection and screening in patients with CAD, and this system should not replace the Doppler method in populations at high risk of cardiovascular disease.

Beneficial influence of carvedilol on urologic indices in patients with hypertension and benign prostatic hyperplasia: results of a randomized, crossover study.

OBJECTIVE To assess the influence of carvedilol, an α- and β-blocker, on lower urinary tract symptoms (LUTS) and urine flow in hypertensive patients with benign prostatic hyperplasia (BPH). METHODS Fifty men were included in this double blind crossover study with placebo. After initial screening, participants were randomized to the carvedilol or the enalapril group, with cross over after 3 months. Doses of both drugs were uptitrated or additional therapy was introduced to ensure normal control of blood pressure (BP). Urologic assessment included uroflowmetry (average [Qavg] and maximum urinary flow rate [Qmax]), postvoid residual urine volume (PVR), International Prostate Symptom Score (IPSS), and prostate-specific antigen (PSA). RESULTS After carvedilol or enalapril administration, BP values were significantly reduced, whereas heart rate decreased only in the carvedilol group. Basal urologic values for carvedilol and enalapril were similar: Qavg, 7.8 ± 0.9 and 8.1 ± 0.6 mL/s; Qmax, 13.2 ± 1.5 and 13.7 ± 0.9 mL/s; PVR, 86.1 ± 13.2 and 85.6 ± 11.7 mL; and IPSS, 13.2 ± 0.9 and 12.3 ± 0.8 points, respectively. After treatment with carvedilol, PVR and IPSS significantly decreased (48.2 ± 11.7 mL, 9.0 ± 0.8 points, respectively; P <.001), whereas Qavg and Qmax increased (10.3 ± 0.9 mL/s, 16.5 ± 1.4 mL/s, respectively; P <.001). In the enalapril group, all of these values remained unchanged. CONCLUSION Carvedilol, compared with enalapril, has a positive influence on LUTS related to BPH in patients with hypertension. Thus, therapy with carvedilol may be considered in hypertensive patients with BPH. Further studies on the urologic benefit from long-term use of the drug are warranted.

Long lasting dysautonomia due to botulinum toxin B poisoning: clinical-laboratory follow up and difficulties in initial diagnosis.

BackgroundBotulism is an acute form of poisoning caused by one of four types (A, B, E, F) toxins produced by Clostridium botulinum, ananaerobic, spore forming bacillus. Usually diagnosis of botulism is considered in patients with predominant motor symptoms: muscle weakness with intact sensation and preserved mental function.Case presentationWe report a case of 56-year-old Caucasian female with a history of arterial hypertension, who presented with acute respiratory failure and bilateral ptosis misdiagnosed as brainstem ischemia. She had severe external and internal ophtalmoplegia, and autonomic dysfunction with neither motor nor sensory symptoms from upper and lower limbs. Diagnosis of botulinum toxin poisoning was made and confirmed by serum antibody testing in the mouse inoculation test.ConclusionsOphtalmoplegia, autonomic dysfunction and respiratory failure can be caused by botulism. Early treatment and intensive care is essential for survival and recovery. The electrophysiological tests are crucial to correct and rapid diagnosis. Botulism (especially type B) should be considered in any case of acute or predominant isolated autonomic dysfunction.

Atrial fibrillation does not affect ankle–brachial index measured using the Doppler method

Atrial fibrillation may affect blood pressure measurements. The ankle–brachial index (ABI) is a ratio of systolic blood pressure measured on the lower and upper limbs that may also be affected by arrhythmia. The purpose of the study was to investigate whether atrial fibrillation influenced ABI results. Ninety-nine patients (age 66.6±11 years, 63 males and 36 females) who underwent electrical cardioversion of atrial fibrillation were investigated. ABI measurements using the Doppler method were performed on both lower extremities before and after electrical cardioversion. Measurements were repeated three times and then averaged. The ABI using both lower limbs was lower before electrical cardioversion than after restoration to sinus rhythm (right side: 1.132 (1.065–1.210) during atrial fibrillation vs. 1.179 (1.080–1.242) in sinus rhythm, P=0.019; left side: 1.142 (1.075–1.222) during atrial fibrillation vs. 1.170 (1.098–1.255) in sinus rhythm, P=0.011). However, the upper 95% confidence interval (CI) margins for the median differences in ABI were 0.045 and 0.040 for right and left, respectively, suggesting that the observed difference was clinically insignificant. There was a significant correlation between measurements obtained before and after electrical cardioversion on both lower limbs (r=0.61, P<0.001 and r=0.67, P<0.001). The Bland–Altman plot showed good agreement between measurements performed using the Doppler method during atrial fibrillation and sinus rhythm. Study results showed that atrial fibrillation did not have a clinically important effect on ABI measurements.