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219 results on '"Schoemaker, Rik C."'

5. Motilin effects on the proximal stomach in patients with functional dyspepsia and healthy volunteers

Author

Kamerling, Ingrid M.C., Van Haarst, Aernout D., Burggraaf, Jacobus, Schoemaker, Rik C., Biemond, Izak, Heinzerling, Hartmut, Jones, Richard, Cohen, Adam F., and Masclee, Ad A.M.

Subjects
Gastrointestinal system -- Physiological aspects, Nausea -- Physiological aspects, Indigestion -- Physiological aspects, Biological sciences
Abstract

This study investigates motilin effects on the proximal stomach in patients with functional dyspepsia (FD) and healthy volunteers. Eight healthy volunteers and 12 patients with FD were infused with synthetic motilin or placebo. Proximal gastric volume was measured with a barostat at constant pressure and during isobaric distensions. Abdominal symptoms were scored by visual analog scales. Plasma motilin concentrations were measured by radioimmunoassay. Motilin concentrations and baseline gastric volumes were similar for patients and healthy volunteers. Motilin, compared with placebo, reduced gastric volume by 112 ml [F(29,195); confidence interval (CI) 95%] in patients and by 96 ml [F(-7,200); CI 95%] in healthy volunteers. In patients, motilin decreased compliance by 76 mi/ mmHg [F(9,143); CI 95%] compared with placebo, which was similar in volunteers [66 mi/mmHg; F(11,120); CI 95%]. Patients were more nauseous during motilin compared with placebo (P = 0.04), whereas healthy volunteers did not experience nausea. We conclude that in a fasted condition, FD patients have a similar proximal gastric motor response to motilin as healthy volunteers, but experience an exaggerated sensation of nausea. barostat; gastric volume; gastric volume waves

Published
2003

26. Hyposomatotropism Blunts Lipolysis in Abdominally Obese Women

Author

Buijs, Madelon M., Burggraaf, Jacobus, Langendonk, Janneke G., Schoemaker, Rik C., Frölich, Marijke, Arndt, Jan-Willem, Cohen, Adam F., Romijn, Johannes A., Ackermans, Mariette T., Sauerwein, Hans P., Meinders, A. Edo, and Pijl, Hanno

Published
2002

44. A placebo-controlled parallel study of the effect of two types of coffee oil on serum lipids and transaminases: identification of chemical substances involved in the cholesterol-raising effect of coffee

Author

Rooij, Jeroen van, Stegen, Gerrit H.D. van der, Schoemaker, Rik C., Kroon, Cees, Burggraaf, Jacobus, Hollaar, Leny, Vroon, Ton F.F.P., Smelt, Augustinus H.M., and Cohen, Adam F.

Subjects
Coffee -- Physiological aspects, Blood cholesterol -- Measurement, Diterpenes -- Physiological aspects, Food/cooking/nutrition, Health
Abstract

In a randomized double-blind parallel study in 36 subjects the effect on serum cholesterol of a daily dose of 2 g lipid extracted from green Arabica and Robusta coffee beans was studied. Arabica oil elevated serum total cholesterol by 1.1 mmol/L (95% CI for the difference from placebo: 0.41, 1.73 mmol/L); the effect of robusta oil (+0.5 mmol/L) was not statistically significant (95% CI: -0.01, 0.92 mmol/L). Arabica oil also raised plasma triglycerides by 0.8 mmol/L (95% CI: 0.26, 1.25 mmol/L). The effect of robusta oil on triglycerides was +0.14 mmol/L and not significant (95% CI: -0.26, 0.42 mmol/L). In the 12 subjects taking arabica oil an average serum alanine amino-transferase elevation of 18 U/L (95% CI: 9.4, 28.4 U/L) was observed. Because only arabica oil contains kahweol and arabica coffee contains more cafestol than does robusta oil, this is further evidence for the role of diterpenes in the rise of serum cholesterol and alanine aminotransferase after consumption of boiled coffee.

Published
1995

46. Estimation of growth hormone secretion rate: impact of kinetic assumptions intrinsic to the analytical approach

Author

LANGENDONK, JANNEKE G., VELDHUIS, JOHANNES D., BURGGRAAF, JACOBUS, SCHOEMAKER, RIK C., COHEN, ADAM F., MEINDERS, A. EDO, and PIJL, HANNO

Subjects
Somatotropin -- Physiological aspects, Obesity -- Physiological aspects, Biological sciences
Abstract

Estimation of growth hormone secretion rate: impact of kinetic assumptions intrinsic to the analytical approach. Am J Physiol Regulatory Integrative Comp Physiol 280: R225-R232, 2001.--We compared four common mathematical techniques to determine daily endogenous growth hormone (GH) secretion rates from diurnal plasma GH concentration profiles in 24 women (16 upper- or lower-body obese and 8 normal-weight individuals). Two forms of deconvolution analysis and two techniques based on a priori determined GH clearance estimates were employed. Deconvolution analyses revealed significant differences in the 24-h GH secretion rate between normal-weight and upper-body obese women, whereas the other two techniques did not. Moreover, deconvolution analyses predicted that the reduction in mean plasma GH concentrations in upper-body obese women was accounted for by impaired GH secretion, whereas the other methods suggested that obesity increases GH metabolic clearance. Thus we infer that disparate conclusions concerning GH secretion can be drawn from the same primary data set. The different inferences likely reflect dissimilar kinetic assumptions and the particular limitations intrinsic to each analytical approach. Accordingly, we urge caution in the facile comparison of calculated GH secretion data in humans, especially when kinetic and secretion measurements are performed under different conditions. The most appropriate way to determine the GH secretion rate in humans must be balanced by the exact intent of the experiment and the acceptability of different assumptions in that context. human obesity

Published
2001

47. Influence of obesity and body fat distribution on growth hormone kinetics in humans

Author

LANGENDONK, JANNEKE G., MEINDERS, A. EDO, BURGGRAAF, JACOBUS, FROLICH, MARIJKE, ROELEN, CORNE A. M., SCHOEMAKER, RIK C., COHEN, ADAM F., and PIJL, HANNO

Subjects
Obesity -- Physiological aspects, Adipose tissues -- Distribution, Somatotropin -- Physiological aspects, Menopause -- Physiological aspects, Biological sciences
Abstract

Langendonk, Janneke G., A. Edo Meinders, Jacobus Burggraaf, Marijke Frolich, Corne A. M. Roelen, Rik C. Schoemaker, Adam F. Cohen, and Hanno Pijl. Influence of obesity and body fat distribution on growth hormone kinetics in humans. Am. J. Physiol. 277 (Endocrinol. Metab. 40): E824-E829, 1999.--We studied the kinetics of exogenous recombinant 22-kDa human growth hormone (rhGH) in premenopausal women with upper body obesity (UBO), lower body obesity (LBO), or normal body weight. A bolus of 100 mU rhGH was administered during a continuous infusion of somatostatin to suppress endogenous GH secretion. GH kinetics were investigated with noncompartmental analysis of plasma GH curves. GH peak values in response to GH infusion and plasma half-life of GH were not significantly different between normal weight and obese subjects. In contrast, GH clearance was 33% higher in LBO women and 51% higher in UBO women compared with clearance in normal weight controls. The difference in clearance between LBO and UBO was not statistically significant. Altered GH clearance characteristics contribute to low circulating GH levels in obese humans. Body fat distribution does not appear to affect GH kinetics. somatotropin; clearance; distribution volume; fat mass; fat distribution

Published
1999

49. Central nervous system effects of moxonidine experimental sustained release formulation in patients with mild to moderate essential hypertension

Author

Kemme, Michiel J B, Post, Jeroen P vd, Schoemaker, Rik C, Straub, Matthias, Cohen, Adam F, and van Gerven, Joop M A

Subjects
Adult, Male, Imidazoles, Blood Pressure, Electroencephalography, Drug Tolerance, Middle Aged, Pharmacodynamics, Heart Rate, Delayed-Action Preparations, Hypertension, Saccades, Humans, Female, Antihypertensive Agents, Aged
Abstract

The primary aim was to demonstrate that moxonidine, given in an experimental sustained release (SR) formulation, had no clinically relevant central nervous system (CNS) effects after 4 weeks of treatment. A clinically relevant CNS effect was predefined as more than 45 degrees s-1 reduction in saccadic peak velocity (SPV), corresponding to the effects of one night's sleep deprivation.In a randomized, double-blind fashion, 35 patients with mild to moderate essential hypertension received placebo run-in medication for 2 weeks, followed by 4 weeks' moxonidine sustained release (1.5 mg o.d.) or placebo. On the first day and 1 and 4 weeks following the start of treatment, blood pressure was measured and CNS effects were assessed using SPV, visual analogue scales and EEG.On day 1 there was a significant, but not clinically relevant, reduction in the time-corrected area under the effect curve (AUEC) for SPV in the moxonidine group compared with placebo [difference of 38 degrees s-1; 95% confidence interval (CI) 23, 52]. This difference was no longer significant after one (9 degrees s-1; 95% CI -17, 35) and 4 weeks (6.9 degrees s-1; 95% CI -16, 30). Visual analogue scales for alertness showed similar results. A decrease in EEG alpha- and beta-power and an increase in delta-power were only found on day 1 of moxonidine treatment. The AUEC for systolic/diastolic blood pressure relative to placebo was 23 (95% CI 17, 29)/13 (9, 16) mmHg lower on day 1 and remained reduced by 20 (11, 30)/12 (6, 17) and 15 (6, 25)/9 (3, 15) mmHg after 1 and 4 weeks' moxonidine treatment.Four weeks' treatment with an experimental SR formulation resulted in tolerance to CNS effects (equivalence to placebo) while blood pressure-lowering effects remained adequate. The tolerance to CNS effects was already observed after 1 week of treatment.

Published
2003

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