Kenneth Meijer

Dr. Kenneth Meijer

Maastricht University, The Netherlands
orcid

Research Focus & Metrics

Academic Career Length

31Years (1996-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 February 2001 in Transplantation
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Journal Article
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HHHerman G.D. Hendriks
Herman G.D. Hendriks
KMKarina Meijer
Karina Meijer
JWJoost Th.M. de Wolf
Joost Th.M. de Wolf
IKIds J. Klompmaker
Ids J. Klompmaker
RPRobert J. Porte
Robert J. Porte
JMJan van der Meer
Jan van der Meer
Large transfusion requirements, i.e., excessive blood loss, during orthotopic liver transplantation (OLT) are correlated with increased morbidity and mortality. Recombinant factor VIIa (rF-VIIa) has been shown to improve hemostasis in a variety of conditions, but has never been studied in liver transplantation. We performed a single-center, open-label, pilot study in adult patients undergoing OLT for cirrhosis Child-Pugh B or C, to assess efficacy and safety of rFVIIa. rFVIIa (80 microg/kg) was administered at the start of the operation, to be repeated according to predefined criteria. Packed red blood cells (RBC), fresh-frozen plasma, and platelet concentrates were administered according to predefined criteria. Perioperative transfusion requirements in study patients were compared with matched controls. Six patients were enrolled in the study. All received a single dose of rFVIIa. Transfusion requirements (given as median, with range in parentheses) were lower in the study group than in matched controls: 1.5 (0-5) vs. 7 (2-18) units of allogeneic RBC (P=0.006), 0 (0-2) vs. 3.5 (0-23) units of autologous RBC (P=0.043), total amount of RBC 3 (0-5) vs. 9 (4-40) units (P=0.002). Transfused fresh-frozen plasma was 1 (0-7) vs. 8 (2-35) units (P=0.011). Blood loss was 3.5 L (1.4-5.3) vs. 9.8 L (3.7-35.0) (P=0.004). One study patient developed a hepatic artery thrombosis at day 1 postoperatively. A single dose of 80 microg/kg rFVIIa significantly reduced transfusion requirements during OLT. Further study is needed to establish the optimally effective and safe dose of rFVIIa in orthotopic liver transplantation.

1 April 2009 in Physiological Measurement
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Journal Article
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SPStephen J Preece
Stephen J Preece
JGJohn Y Goulermas
John Y Goulermas
LKLaurence Kenney
Laurence Kenney
DHDave Howard
Dave Howard
KMKenneth Meijer
Kenneth Meijer
RCRobin Crompton
Robin Crompton
With the advent of miniaturized sensing technology, which can be body-worn, it is now possible to collect and store data on different aspects of human movement under the conditions of free living. This technology has the potential to be used in automated activity profiling systems which produce a continuous record of activity patterns over extended periods of time. Such activity profiling systems are dependent on classification algorithms which can effectively interpret body-worn sensor data and identify different activities. This article reviews the different techniques which have been used to classify normal activities and/or identify falls from body-worn sensor data. The review is structured according to the different analytical techniques and illustrates the variety of approaches which have previously been applied in this field. Although significant progress has been made in this important area, there is still significant scope for further work, particularly in the application of advanced classification techniques to problems involving many different activities.

1 January 2007 in American Journal of Physiology-Endocrinology and Metabolism
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Journal Article
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LVLex Verdijk
Lex Verdijk
RKRene Koopman
Rene Koopman
GSGert Schaart
Gert Schaart
KMKenneth Meijer
Kenneth Meijer
HSHans H. C. M. Savelberg
Hans H. C. M. Savelberg
LLLuc Van Loon
Luc Van Loon
Satellite cells (SC) are essential for skeletal muscle growth and repair. Because sarcopenia is associated with type II muscle fiber atrophy, we hypothesized that SC content is specifically reduced in the type II fibers in the elderly. A total of eight elderly (E; 76 ± 1 yr) and eight young (Y; 20 ± 1 yr) healthy males were selected. Muscle biopsies were collected from the vastus lateralis in both legs. ATPase staining and a pax7-antibody were used to determine fiber type-specific SC content (i.e., pax7-positive SC) on serial muscle cross sections. In contrast to the type I fibers, the proportion and mean cross-sectional area of the type II fibers were substantially reduced in E vs. Y. The number of SC per type I fiber was similar in E and Y. However, the number of SC per type II fiber was substantially lower in E vs. Y (0.044 ± 0.003 vs. 0.080 ± 0.007; P < 0.01). In addition, in the type II fibers, the number of SC relative to the total number of nuclei and the number of SC per fiber area were also significantly lower in E. This study is the first to show type II fiber atrophy in the elderly to be associated with a fiber type-specific decline in SC content. The latter is evident when SC content is expressed per fiber or per fiber area. The decline in SC content might be an important factor in the etiology of type II muscle fiber atrophy, which accompanies the loss of skeletal muscle with aging.

5 February 2009 in The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences
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LVLex Verdijk
Lex Verdijk
BGBenjamin G. Gleeson
Benjamin G. Gleeson
RJRichard A. M. Jonkers
Richard A. M. Jonkers
KMKenneth Meijer
Kenneth Meijer
HSHans H. C. M. Savelberg
Hans H. C. M. Savelberg
LLLuc Van Loon
Luc Van Loon
We determined muscle fiber type–specific hypertrophy and changes in satellite cell (SC) content following a 12-week resistance training program in 13 healthy, elderly men (72 ± 2 years). Leg strength and body composition (dual-energy X-ray absorptiometry and computed tomography) were assessed, and muscle biopsy samples were collected. Leg strength increased 25%–30% after training (p < .001). Leg lean mass and quadriceps cross-sectional area increased 6%–9% (p < .001). At baseline, mean fiber area and SC content were smaller in the Type II versus Type I muscle fibers (p < .01). Following training, Type II muscle fiber area increased from 5,438 ± 319 to 6,982 ± 503 μm2 (p < .01). Type II muscle fiber SC content increased from 0.048 ± 0.003 to 0.084 ± 0.008 SCs per fiber (p < .001). No changes were observed in the Type I muscle fibers. In older adults, skeletal muscle tissue is still capable of inducing SC proliferation and differentiation, resulting in Type II muscle fiber hypertrophy.

6 August 2021 in Nature Communications
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LGL. Grevendonk
L. Grevendonk
NCN. J. Connell
N. J. Connell
Christopher McCrumChristopher McCrum
Christopher McCrum
CFC. E. Fealy
C. E. Fealy
LBL. Bilet
L. Bilet
JHJ. Hoeks
J. Hoeks
The relationship between the age-associated decline in mitochondrial function and its effect on skeletal muscle physiology and function remain unclear. In the current study, we examined to what extent physical activity contributes to the decline in mitochondrial function and muscle health during aging and compared mitochondrial function in young and older adults, with similar habitual physical activity levels. We also studied exercise-trained older adults and physically impaired older adults. Aging was associated with a decline in mitochondrial capacity, exercise capacity and efficiency, gait stability, muscle function, and insulin sensitivity, even when maintaining an adequate daily physical activity level. Our data also suggest that a further increase in physical activity level, achieved through regular exercise training, can largely negate the effects of aging. Finally, mitochondrial capacity correlated with exercise efficiency and insulin sensitivity. Together, our data support a link between mitochondrial function and age-associated deterioration of skeletal muscle.

16 June 2017 in Geriatrics & Gerontology International
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MGMarissa H.G. Gerards
Marissa H.G. Gerards
Christopher McCrumChristopher McCrum
Christopher McCrum
AMAvril Mansfield
Avril Mansfield
KMKenneth Meijer
Kenneth Meijer
Falls are a leading cause of injury, hospitalization and even death among older adults. Although various strength and balance exercise interventions have shown moderate reductions in falls incidence among healthy older adults, no significant falls incidence improvements have been consistently seen in frail older adults or in patient groups with an increased falls risk (e.g. people with Parkinson's disease and stroke). This might be due to a lack of task specificity of previous exercise interventions to the recovery actions required to prevent a fall. Perturbation‐based balance training (PBT) is an emerging task‐specific intervention that aims to improve reactive balance control after destabilizing perturbations in a safe and controlled environment. Although early studies were carried out predominantly in research laboratory settings, work in clinical settings with various patient groups has been proliferating. A systematic search of recent PBT studies showed a significant reduction of falls incidence among healthy older adults and certain patient groups (e.g. people with Parkinson's disease and stroke), with clinically relevant reductions in frail older adults. The most practical methods in clinical settings might be treadmill‐based systems and therapist‐applied perturbations, and PBT that incorporates multiple perturbation types and directions might be of most benefit. Although more controlled studies with long‐term follow‐up periods are required to better elucidate the effects of PBT on falls incidence, PBT appears to be a feasible and effective approach to falls reduction among older adults in clinical settings. Geriatr Gerontol Int 2017; 17: 2294–2303..