Papers by Jan van der Meulen
Angiology, 1999
Day-activity rhythms of heart rate and blood pressure are thought to be mediated mainly through t... more Day-activity rhythms of heart rate and blood pressure are thought to be mediated mainly through the sympathetic nervous system and may have greater amplitudes in patients with hypertension owing to increased daytime and largely normal nighttime values. Drug-induced nighttime hypotension in patients with chronic hypertension has been associated with the precipitation of cardiac failure and a fall in cerebral flow. The authors examined the effects of a single dose and of a 4-week treatment with different classes of antihypertensive drugs on ambulatory blood pressure (ABP) in 10 patients with mild hypertension. Data were assessed by polynomial analysis (Harvard Graphics 3). A single oral dose of enalapril 10 mg, amlodipine 5 mg, carvedilol 25 mg, and celiprolol 200 mg produced a mean reduction of 24-hour ABP compared to placebo of, respectively, 24/11, 11/5, 13/6, and 12/5 mm Hg (p values between <0.02 and <0.001). With enalapril, amlodipine, and carvedilol, between-subject variability contributed significantly to the overall variability in the measurements (p values between 0.05 and 0.01 versus zero), whereas with celiprolol this was not so. Although the beta blockers reduced daytime blood pressures similarly to the ACE inhibitor or the calcium channel blocker, they did not reduce nighttime blood pressures. These results were confirmed by an 8-week crossover trial comparing enalapril 10 mg daily with celiprolol 200 mg daily in the same group of patients. The authors conclude (1) that beta blockers produce a more stable reduction of blood pressure in patients with mild hypertension less affected by pressor effects through the sympathetic nervous system; (2) that beta blockers, unlike ACE inhibitors and calcium channel blockers, do not give rise to nighttime hypotension in this category of patients; and (3) that the selective beta blocker celiprolol may even perform better in these respects than the nonselective beta blocker carvedilol.
Angiology, 1998
Fatigue is an important symptom of a disturbed circadian rhythm. To date, no studies of circadian... more Fatigue is an important symptom of a disturbed circadian rhythm. To date, no studies of circadian rhythms in patients with chronic fatigue syndrome (CFS) have been published. The objectives of the study were to study rhythms of heart rate and systolic and diastolic blood pressure in patients with chronic fatigue syndrome compared with age-matched normotensive controls and to study the effects of melatonin and inopamil on such rhythms. Ambulatory blood pressure (ABP) measurements (Space Lab, Inc, validated) of 18 patients with CFS were made according to the 1987 U.S. Center for Disease Control Criteria, and measurements of 12 age-matched normotensive controls were used in a cosinor analysis of the two groups. The effects of melatonin and inopamil on ABP were studied subsequently in four patients in an 8-week open-label evaluation. One patient was hypertensive (diastolic blood pressure > 90 mm Hg at least once every 4 hours), and was, therefore, excluded. The data of the remaining 17 patients (15 women, 2 men) revealed a significant 12-hour rhythm in heart rate and 24-hour rhythm in systolic and diastolic blood pressure with 95% confidence intervals not significantly different from sinusoidal patterns. Although these rhythms were synchronous with the control group rhythms, their amplitudes were not and showed, respectively, 2.8, 2.8, and 9.0 times the size of the control group rhythms (p < 0.001, p < 0.001, and p < 0.0001, respectively). Systolic blood pressures in the patients with CFS were consistently below 100 mm Hg during the nighttime. In a subsequent pilot study of four patients from the study population treated with melatonin 4 mg daily and inopamil 200 mg daily for 4 weeks, inopamil reduced nighttime hypotension (p < 0.05), whereas melatonin increased nighttime hypotension (p < 0.02). Patients with CFS have increased amplitudes of circadian rhythms and systolic blood pressures consistently below 100 mm Hg during the nighttime. Positive inotropic compounds may be beneficial in such patients, but melatonin may not be.
Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis
We investigated the effect of different i.p. dwell times of dialysis fluid on the composition and... more We investigated the effect of different i.p. dwell times of dialysis fluid on the composition and phagocytic capacity of the peritoneal cells. We examined dialysate after 1.5 and 15 h dwell time in 10 continuous cyclic peritoneal dialysis (CCPD) patients and after 8 h dwell time in 14 continuous ambulatory peritoneal dialysis (CAPD) patients. There was no significant difference in viability, composition, and Fc receptor positive cells among the peritoneal cells in the studied effluents of CCPD and CAPD patients. However, the yield of peritoneal cells and the phagocytic capacity of IgG-coated sheep red blood cells ([lgG]SRBC) by peritoneal macro phages in 1.5 h dwell time dialysate was significantly decreased when compared with 15 h dwell time dialysates. In addition, the total phagocytic capacity of peritoneal cells in 1.5 h dwell time dialysate is dramatically decreased when compared with the 15 h dwell time dialysate and 8 h dwell time dialysate of CAPD patients. These findings mu...
The Journal of Clinical Pharmacology, 1998
Journal of Cardiovascular Pharmacology, 1996
Clinical Research and Regulatory Affairs, 1998
Annals of Internal Medicine, 1994
American Journal of Therapeutics, 1996
Critical Care Medicine, 1990
We retrospectively studied relations between age, pre-existing chronic disease, sepsis, organ sys... more We retrospectively studied relations between age, pre-existing chronic disease, sepsis, organ system failure, and mortality in 487 patients from a medical ICU. Single organ system failure (SOSF) occurred in 136 (28%) and multiple (greater than or equal to 2) organ system failure (MOSF) in 187 (38%) patients. Cardiovascular and pulmonary failure predominated. Overall mortality was 27%. SOSF mortality was 16% and for MOSF 58%. Eighty-three percent of nonsurvivors had MOSF. Hence, MOSF is common and a major cause of death in critically ill medical patients. Advancing age and prior chronic disease may diminish physiologic reserve and predispose to sepsis and MOSF. Although sepsis is a major risk factor for MOSF, a nonspecific host response to critical illness may contribute to the syndrome in 35% of patients. Advancing age, chronic disease, and the number of failing organs, particularly failure of cardiovascular, pulmonary, renal, and neurologic systems, are major determinants of overall mortality, but sepsis is not an independent contributor.
Angiology, Aug 1, 1996
In France there are few cardiac deaths in spite of high animal fat intake. France and Italy have ... more In France there are few cardiac deaths in spite of high animal fat intake. France and Italy have the highest overall intake of alcohol in the world. Obviously, there is an inverse association between coronary heart disease (CHD) and alcohol intake in these countries. Although in the past decade several-large scale population studies have confirmed the beneficial effect of alcohol on CHD, these studies may not have been sensitive to control all the confounding variables. No one so far has explored the possibility that the French may be protected by their low level of life stress. In 1993 we conducted a case-control study (n = 118) to examine psychological variables in a group of Dutch males under sixty years of age, before and after acute myocardial infarction (MI). After adjustment for total cholesterol, blood pressure, and smoking, a number of psychological factors appeared to be independently associated with an increased risk of MI. For the present study the same group of patients was assessed for consumption of different types of alcoholic beverages, coffee, sugar, high-fat diet, and vegetables. In the univariate analysis patients appeared to have consumed more red wine (odds ratio [OR] 0.2, P = 0.03) and controls more spirits (OR 4.0, P = 0.005). After adjustment for total cholesterol, blood pressure, and smoking as well as the independent psychological factors, red wine lost its significance (OR 0.4, P = 0.17) whereas the OR for spirits even rose (OR 6.0, P = 0.01). The beneficial effect of wine may be an expression of a relatively low level of life stress. Alcohol itself is not protective but rather a strong risk factor of MI.
Nephron, 1991
The effect of different intraperitoneal dwell times on the phagocytic capacity of the effluent-de... more The effect of different intraperitoneal dwell times on the phagocytic capacity of the effluent-derived macrophages in 6 peritoneal dialysis patients was studied. The number of peritoneal cells increased after longer dwell times, and a significant increase in the percentage of macrophages phagocytosing opsonized sheep red blood cells [( IgG]SRBC) and unopsonized latex beads was determined when the dwell time increased from 1.5 to 15 h. Thus, the total phagocytic capacity of the effluent-derived macrophages dramatically increased with prolonged dwell times. In addition, the IgG concentration showed a five-fold increase following long intraperitoneal dwell times. The increasing IgG levels were accompanied by an increase, however not significant (p less than 0.06), in the opsonic activity of the effluents. The increase in local phagocytic and opsonic capacity following longer intraperitoneal dwell times must be taken in consideration by dialysis fluid exchange schedules of peritoneal dialysis patients.
BMJ open, 2015
Prostate cancer mortality (PCM) in the USA is among the lowest in the world, whereas PCM in Engla... more Prostate cancer mortality (PCM) in the USA is among the lowest in the world, whereas PCM in England is among the highest in Europe. This paper aims to assess the association of variation in use of definitive therapy on risk-adjusted PCM in England as compared with the USA. Observational study. Cancer registry data from England and the USA. Men diagnosed with non-metastatic prostate cancer (PCa) in England and the USA between 2004 and 2008. Competing-risks survival analyses to estimate subhazard ratios (SHR) of PCM adjusted for age, ethnicity, year of diagnosis, Gleason score (GS) and clinical tumour (cT) stage. 222 163 men were eligible for inclusion. Compared with American patients, English patients were more likely to present at an older age (70-79 years: England 44.2%, USA 29.3%, p<0.001), with higher tumour stage (cT3-T4: England 25.1%, USA 8.6%, p<0.001) and higher GS (GS 8-10: England 20.7%, USA 11.2%, p<0.001). They were also less likely to receive definitive therapy...
NDT Plus, 2008
... Schweitzer Hospital, Dordrecht, The Netherlands. C. Siemes, Department of Internal Medicine, ... more ... Schweitzer Hospital, Dordrecht, The Netherlands. C. Siemes, Department of Internal Medicine, Albert Schweitzer Hospital, PO Box 444, 3318 AT Dordrecht, The Netherlands. Tel: +31-78-6542351; E-mail: siemescl{at}asz.nl. Received January 9, 2008. Accepted March 20, ...
Kidney International, 1992
Peritoneal defense in continuous ambu'atory peritoneal dialysis versus continuous cyclic peritone... more Peritoneal defense in continuous ambu'atory peritoneal dialysis versus continuous cyclic peritoneal dialysis. Several centers have reported a lower rate of peritonitis among adult patients on Continuous cyclic peritoneal dialysis (CCPD) as compared to those undergoing continuous ambulatory peritoneal dialysis (CAPD). Preliminary results of our ongoing prospective randomized study comparing CAPD-Y with CCPD also suggest a lower peritonitis incidence among CCPD-treated patients. To investigate whether the two dialysis regimens could result in differences in local host defense, we studied peritoneal macrophage (PMO) function and effluent opsonic activity in eight patients established on CAPD-Y matched with eight chronic CCPD patients. Since short and long dwell times are inherent to both dialysis modalities, and we previously found that dwell time has an impact on PMO function and effluent opsonic activity, patients were studied after both a short (4 hr) and a long (15 hr) dwell time. In both patient groups PMO phagocytic capacity increased significantly with dwell time (39 3.3% at 4 hr vs. 58 4.2% at 15 hr in CAPD patients, and 40 3.9 vs. 72 3.3% in CCPD patients; P < 0.01), as did PMO peak chemiluminescence response (31 4.9 vs. 77 7.2 counts min'/l04 cells in CAPD, and 22 3.9 vs. 109 21.2 counts min/l04 cells in CCPD; P < 0.01) and effluent opsonic activity (41 7.6 vs. 73 5.8% in CAPD and 39 6.2 vs. 70 5.9% in CCPD; P < 0.01). However, no significant difference was found in either variable between CAPD and CCPD patients when dwell times were equal. In conclusion, no differences were observed in PMO function or effluent opsonic activity between matched CAPD-Y and CCPD patients when dwell times were equal. In both patient groups prolongation of dwell time enhanced PMO function as well as effluent opsonic activity, thereby providing a better host defense. The improvement in peritoneal defenses may, in part, be responsible for the lower peritonitis incidence observed among CCPDtreated patients.
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Papers by Jan van der Meulen