Biomedical subjects

J Troost

Publications and source records attributed to J Troost.

At least 19 recordsLinked to original sources

PubMed2006

Forearm vascular response to nitric oxide and calcitonin gene-related peptide: comparison between migraine patients and control subjects.

The forearm vascular response to nitric oxide (NO) and calcitonin gene-related peptide (CGRP) was investigated in 10 migraine patients and 10 matched control subjects. Changes in forearm blood flow (FBF) during intrabrachial infusion of: (i) serotonin (releasing endogenous NO), (ii) sodium nitroprusside (SNP, exogenous NO-donor), and (iii) CGRP were measured using venous occlusion plethysmography. Flow-mediated dilation (FMD) of the brachial artery, a measure for the endogenous release of NO reactive to occlusion, was measured using ultrasound and expressed as percentage change vs. baseline diameter. FBF ratio (i.e. FBF in the infused over the control arm) at baseline (1.1 +/- 0.1) did not differ between both populations. Serotonin, SNP and CGRP induced a dose-dependent increase (P < 0.001) in FBF ratio in controls (to 2.8 +/- 0.3, 6.7 +/- 1.4 and 6.9 +/- 1.2 at the highest dose, respectively) and migraineurs (2.5 +/- 0.4, 5.6 +/- 0.8 and 6.5 +/- 1.3, respectively); these ratios did not differ between both groups. FMD was comparable in control subjects (5.8 +/- 1%) and migraine patients (5.2 +/- 1%). Based on the forearm vascular response to NO and CGRP, migraine patients do not display generalized changes in vascular function.

Adult↗

PubMed2005

Increasing the daily water intake for the prophylactic treatment of headache: a pilot trial.

Dehydration is commonly believed to result in headache, but the effectiveness of increasing the water intake in patients who frequently suffer from headaches has not been studied thus far. In a pilot study, we examined the possible effects and feasibility of increased water intake in headache patients. Eighteen headache patients (all had migraine, two also had tension-type headache) were randomly allocated to placebo medication, or the advice to additionally drink 1.5 l of water per day, for a period of 12 weeks. Effect measurements consisted of a 2 weeks headache diary and the Migraine Specific Quality of Life (MSQOL) questionnaire. The advice to increase the daily fluid intake by 1.5 l increased the fluid intake in the intervention group by approximately 1 l. This reduced the total hours of headache in 2 weeks by 21 h (95% CI: -48 to 5). Mean headache intensity decreased by 13 mm (95% CI: -32 to 5) on a visual analogue scale (VAS). The effects on MSQOL, number of headache episodes, and medication seemed to be small. The data of the present study suggest a reduction in the total number of hours and intensity of headache episodes after increased water intake. Our results seem to justify larger scaled research on the effectiveness of increased water intake in headache patients.

Confidence Intervals↗

PubMed2004

[Audiologic diagnosis in children. Applicability of different speech material].

The aim of our study was to establish bench-mark values for speech intelligibility in noise for children. We also considered which of the two dichotic discrimination tests, Feldmann's or Uttenweiler's, would be most suitable for use within this age group. We examined 102 children aged between 7 and 10 years (second year, primary school), with an average age of 8 years. After confirming normal hearing acuity (examination of the ear, tympanometry and audiogram), speech perception was tested. This was performed with and without noise using the Göttingen Audiometric Speech Test for Children II and the monosyllables of the Freiburger Speech Intelligibility Test. The percentage of word intelligibility was recorded. Furthermore, dichotic hearing was tested using a combination of Feldmann and Uttenweiler dichotic discrimination tests. We rated the percentage of correct word pair repetitions with the correct article. The results showed that the best method for testing speech perception in noise for this age group was the Göttingen Test II for Children. Speech perception below 70% for word intelligibility should be considered as pathologic. For testing dichotic hearing, Uttenweiler's dichotic discrimination test for children was most suitable. In this test values below 80% should be considered as pathologic.

Child↗

PubMed2003

[A case of fraud in a neurological pharmaceutical clinical trial].

This paper describes the laborious and lengthy path to clarification and disclosure in a case of fraud in a neurological pharmaceutical clinical trial in the Netherlands. A Dutch neurologist was suspected of irregularities within the context of the 'European stroke prevention study 2' (ESPS-2), a multicentre study into medicinal prophylaxis in patients who had suffered a stroke. The Netherlands Society of Neurology (NVN) established an independent inquiry committee for further investigation of the case. The identity of 425 of the 438 patients (97%) included in the trial by the neurologist could be retrieved. The majority of these patients were known to the neurologist with cerebral infarct. For a sample of 115 patients, the general practitioners (GPs) were contacted by means of a questionnaire. Ninety percent of the responding GPs were unaware of their patients' participation in the pharmaceutical clinical trial. A total of forty patients were asked by their GP about participation: 36 (90%; 95%-CI: 76-97) indicated that they had not participated in the trial, and 4 could not remember. The committee concluded that the neurologist had committed fraud, in the sense that he had used the names of existing patients without these patients actually being enrolled in the study. The report of the independent committee was not made public; the committee and the NVN board differed in opinion on the interpretation and implications of the agreements regarding this subject. Following prolonged legal action, the regional Disciplinary Board suspended the neurologist from practice for one year and the court of law sentenced him to 180 days imprisonment or a fee of 130,000 Euro. Based on the experience gained from this case, recommendations in case of suspicion of fraud are discussed, such as the timely appointment of an independent inquiry committee and the establishment of unambiguous agreements regarding the disclosure of the results of the investigation. Possible legal implications should be considered in advance by the organisations involved; statutes should provide regulations for procedural rules. In the Netherlands there now exists a National Body for Scientific Integrity and a committee for the Scientific Integrity of Healthcare Research to prevent scientific misconduct and to stimulate reporting and appropriate handling of this problem.

Clinical Trials as Topic↗

PubMed2003

Determinants of success of inpatient clinical information systems: a literature review.

We reviewed the English and Dutch literature on evaluations of patient care information systems that require data entry by health care professionals published from 1991 to 2001. Our objectives were to identify attributes that were used to assess the success of such systems and to test the ability of a framework developed by Delone and McLean for management information systems(1) to categorize these attributes correctly. The framework includes six dimensions or success factors: system quality, information quality, usage, user satisfaction, individual impact, and organizational impact. Thirty-three papers were selected for complete review. Types of study design included descriptive, correlational, comparative, and case studies. A variety of relevant attributes could be assigned to the six dimensions in the Delone and McLean framework, but some attributes, predominantly in cases of failure, did not fit any of the categories. They related to contingent factors, such as organizational culture. Our review points out the need for more thorough evaluations of patient care information systems that look at a wide range of factors that can affect the relative success or failure of these systems.

Computer Security↗

PubMed2003

Abnormal warm and cold sensation thresholds suggestive of small-fibre neuropathy in sarcoidosis.

OBJECTIVE: A substantial number of sarcoidosis patients report apparently non-specific symptoms such as pain, for which no organic substrate has yet been found. Recently we observed symptoms suggestive of small-fibre neuropathy in a group of sarcoidosis patients. The aim of the present study was to verify this observation using various electrophysiological tests. METHODS: In 74 sarcoidosis patients complaining of symptoms suggestive of small-fibre neuropathy, thresholds for warm (WS) and cold sensation (CS) as well as for heat pain were determined at the thenar eminence and the foot dorsum. Furthermore, sympathetic skin responses (SSR), nerve conduction studies and concentric needle electromyography were performed. In 31 patients, cardiovascular autonomic testing was carried out. RESULTS: Thermal threshold testing (TTT) revealed abnormalities in 51 of the 74 patients. Abnormalities showed an asymmetrical distribution. WS was affected more often than CS and feet more often than hands. Nerve conduction studies in the legs showed slightly abnormal results in 6 patients; all of these had abnormal TTT results. The SSR was absent at the foot in 7 patients. Cardiovascular autonomic testing was abnormal in only a single patient. CONCLUSIONS: In a subgroup of sarcoidosis patients we found TTT abnormalities suggestive of small-fibre neuropathy. SSR and cardiovascular autonomic testing appeared to be of little diagnostic value. Small-fibre neuropathy may be the cause of a number of hitherto unexplained symptoms in sarcoidosis.

Adult↗

PubMed2003

Usefulness of language and memory testing during intracarotid amobarbital testing: observations from an fMRI study.

BACKGROUND: Several procedures for testing language lateralization and memory function exist during the intracarotid amobarbital test (IAT). The use of functional magnetic resonance imaging (fMRI) gives the opportunity to assess the validity of some of these procedures, or at least to inspect the neuronal correlates. A comprehensive fMRI protocol was tested, aimed at addressing aspects of lateralization of language, as well as testing memory in relation to activation of mesiotemporal regions. Here we report observations with possible consequences for the current IAT procedures. MATERIALS AND METHODS: The protocol consisted of three language tasks (overt naming, semantic decision and silent word generation) and two memory tasks (encoding and retrieving visual scenes). The paradigms used a block-related procedure in nine right-handed normal volunteers. During the procedure dynamic weighted full brain images were acquired which are sensitive to the blood oxygenation activation effect. RESULTS: Encoding showed symmetrical bilateral activation in the mesiotemporal regions, specifically the hippocampus, parahippocampal gyrus and fusiform gyrus. With a retrieval task activation of the mesiotemporal areas was restricted to the posterior hippocampal area. Overt object naming showed results, similar to encoding tasks with bilateral activation of hippocampal areas. Silent word generation showed much stronger ability to lateralize than the other two language-related tasks and especially object naming. CONCLUSION: Activation revealed by fMRI activation shows that IAT procedures, using active semantic language processing or comprehensive procedures with multiple language tasks have the highest guarantee for individual activation lateralization. Simple object naming does not guarantee a lateralized language fMRI activation pattern. Of the different memory procedures during IAT, the procedures (Interview and the Montreal) demanding encoding processing will be related to larger areas of bilateral hippocampal activation than procedures (Seattle) exclusively requiring retrieval. Moreover, tasks using recognition of previously presented language items (naming objects) are equally effective for assessing hippocampal activation compared with presenting separate memory items.

Adult↗

PubMed2003

Cranial and peripheral interictal vascular changes in migraine patients.

As migraine is associated with an increased risk for ischaemic stroke and peripheral vasospastic disorders, it was hypothesized that interictal vascular changes may be present in migraine patients. Using ultrasound and applanation tonometry, the cardiovascular properties of migraine patients were compared with those of matched control subjects. Vascular parameters of the carotid arteries, cardiac output and systemic vascular resistance did not differ between both groups. Right temporal artery diameter was larger in migraine patients (mean difference 101 micro m; 95% confidence interval (CI) 9/194 micro m; P = 0.033). At the brachial artery, migraine patients displayed a smaller distension (difference -24 micro m; 95% CI -45/-4 micro m; P = 0.021) and a decreased compliance (difference -0.025 mm2/kPa; 95% CI -0.047/-0.003 mm2/kPa; P = 0.024). Thus, migraine patients display an increased peripheral arterial stiffness. The presence of these interictal vascular changes suggests that migraine might be part of a more generalized vascular disorder.

Adult↗

PubMed2003

Thrombin generation in platelet-rich plasma as a tool for the detection of hypercoagulability in young stroke patients.

The time course of the concentration of active thrombin in clotting plasma (the thrombogram) was measured by subsampling from platelet-rich plasma (PRP) and continuous chromogenic measurement of platelet-poor plasma (PPP) in 41 stroke patients under the age of 50, in whom stroke could not be attributed to cardioembolic disease, arterial dissection or vasculitis. A significant increase in the area under the thrombogram (endogenous thrombin potential, ETP) was seen in 23 patients. In 9 of them, ETP was increased in PRP but normal in PPP. High ETP in PRP was significantly associated with stroke, both in the middle and in the highest tercile of the ETP (odds ratio 5.1, range 1.8-15.1, and 3.7, range 1.3-10.3, respectively). A decreased sensitivity to the inhibitory action of thrombomodulin (TM) on thrombin generation was observed in 5 of 37 cases. No further definition of the cause of increased thrombin generation or TM resistance was attempted, except for the role of von Willebrand factor (vWF). ETP in PRP, platelet-derived procoagulant activity and vWF were correlated and higher in patients than in controls (p=0.002, p=0.045 and p=0.0006, respectively). This confirms the correlation between vWF level and stroke at young age found in epidemiological studies. It suggests that the role of vWF in thrombin generation, which has been demonstrated in vitro, may be the underlying mechanism of this correlation. In summary, hypercoagulability, defined as an increased capacity of the platelet plasma system to form thrombin, is found in over half of the patients under 50 years with an otherwise unexplained stroke. Sometimes it is due to increased plasma factor activity, sometimes to an increased procoagulant activity of the platelets.

Adult↗

PubMed2003

Two patient care information systems in the same hospital: beyond technical aspects.

OBJECTIVES: To compare two clinical workstations in one hospital with respect to technical, organizational, cultural and human factors. One clinical workstation was a GUI to the HIS. The other was an electronic patient record for stroke. METHODS: Data were collected by means of in-depth interviews with end-users of both clinical workstations. The interviews were audio taped and transcribed for analysis. RESULTS: End users assessed both clinical workstations as user friendly. Coordination between health care workers was perceived to be enhanced. However, in both situations poor communication between management, implementers and users resulted in uncertainty and skepticism about future perspectives. Further-more, it appeared that inpatient and outpatient settings needed clinical workstations with different requirements for an optimal fit between work practices and information system. CONCLUSIONS: Regardless of the domain and content of a workstation, it can support coordination between disciplines. The communication concerning the information technology strategy deserves much attention. Finally, the requirements for inpatient and outpatient workstations differ.

Attitude of Health Personnel↗

PubMed2002

Developing a comprehensive presurgical functional MRI protocol for patients with intractable temporal lobe epilepsy: a pilot study.

Our aim was to put together and test a comprehensive functional MRI (fMRI) protocol which could compete with the intracarotid amytal (IAT) or Wada test for the localisation of language and memory function in patients with intractable temporal lobe epilepsy. The protocol was designed to be performed in under 1 h on a standard 1.5 tesla imager. We used five paradigms to test nine healthy right-handed subjects: complex scene-encoding, picture-naming, reading, word-generation and semantic-decision tasks. The combination of these tasks generated two activation maps related to memory in the mesial temporal lobes, and three language-related maps of activation in a major part of the known language network. The functional maps from the encoding and naming tasks showed typical and symmetrical posterior mesial temporal lobe activation related to memory in all subjects. Only four of nine subjects also showed symmetrical anterior hippocampal activation. Language lateralisation was best with the word generation and reading paradigms and proved possible in all subjects. The reading paradigm enables localisation of language function in the left anterior temporal pole and middle temporal gyrus, areas typically resected during epilepsy surgery. The combined results of this comprehensive f MRI protocol are adequate for a comparative study with the IAT in patients with epilepsy being assessed for surgery.

Adult↗

PubMed2002

Baclofen inhibits ANP-mediated cyclic GMP synthesis in the rat cervical spinal cord.

The neurotransmitter gamma-aminobuteric acid (GABA) is believed to have a controlling action on spinal locomotor networks. In spasticity, spinal locomotor networks are thought to play a role. A well known drug in the treatment of spasticity is the GABA(B) agonist Baclofen. We report an inhibitory effect of Baclofen on the ANP-mediated cGMP synthesis in the superficial dorsal horn (laminae I-III) of the rat cervical spinal cord. This inhibitory effect of Baclofen could not be detected after incubation with the NO donor SNP. The clinical effect of Baclofen on the reduction of spasticity might be explained by an enhancement of GABAergic inhibition of ANP mediated cGMP concentration in the spinal cord dorsal horn, thus reducing afferent input.

Aging↗

PubMed2002

Developmental apoptosis in the spinal cord white matter in neonatal rats.

We investigated developmental apoptosis in the white matter of the cervical spinal cord at postnatal days 2, 5, and 8. Apoptotic cells were labeled using TUNEL and caspase-3 immunostaining. Apoptotic cells were diffusely distributed throughout the white matter of the spinal cord. The total amount of apoptotic cells in the cervical spinal cord white matter was related to postnatal age, with the lowest at P2 (mean 7.9, SD 5.6) and the highest at P8 (mean 109, SD 21.4). Using double immunostaining for ED-1 and O4, apoptotic cells were identified as microglia and oligodendrocytes.

Aging↗

PubMed2002

Apoptosis in the rat spinal cord during postnatal development; the effect of perinatal asphyxia on programmed cell death.

The aim of our study was to investigate the effect of perinatal asphyxia on developmental apoptosis in the cervical and lumbar spinal cord in the neonatal rat. Perinatal asphyxia was induced by keeping pups at term in utero in a water bath at 37 degrees C for 20 min, followed by resuscitation. Effects of this treatment on developmental apoptosis were studied on postnatal days 2, 5 and 8 using terminal deoxynucleotidyl transferase (TdT)-dUTP-biotin nick end labelling (TUNEL) and caspase-3 staining. TUNEL positive cells were identified using double immunostaining. On postnatal day 2 an increase of 215% in TUNEL positive cells was detected (P=0.005) in laminae IV-VII of the lumbar spinal cord of rats which underwent perinatal asphyxia compared to controls. An increase of 55% compared to controls (P=0.03) was seen in laminae I-III of the lumbar spinal cord at postnatal day 8. TUNEL positive cells could be partly identified as microglia cells (ED1 positive) and oligodendrocytes (O4 positive). The effect of perinatal asphyxia on programmed cell death in the neonatal rat spinal cord was mainly observed in the intermediate zone and dorsal horn of the lumbar spinal cord. We conclude that perinatal asphyxia has a pronounced effect on the survival of cells in a specific region of the spinal cord and thus may have a profound effect on the development of motor networks.

Animals↗

PubMed2002

Prognostic value of blood pressure in acute stroke.

Manipulation of blood pressure (BP) in acute stroke may improve outcome. Despite various studies, data on the prognostic significance of early BP in stroke remain unclear. Therefore, we studied the relationship between various BP variables in the acute phase of stroke and functional outcome at 3 months. Blood pressures were collected by reviewing BP records of 817 patients who were admitted to our stroke unit between 1987 and 1992. Besides the first systolic and diastolic admission BP (SBP and DBP), we also used the mean of the daytime as well as the night-time systolic and diastolic BP values. Finally, we studied the relationship between the decrease in BP between day 0 and 4 and outcome. As dependent outcome variable we used the Rankin handicap score at 3 months dichotomized in a score >3 (poor outcome) vs a score 3 (good outcome). A total of 430 patients were admitted within 24 h following stroke onset. There was no significant relationship between the systolic and diastolic BP and the outcome at 3 months. Only night-time systolic BP 165 mm Hg (odds ratio (OR) 2.8; 95% CI 1.1-6.8), night-time diastolic BP 60 mm Hg (OR 8.1; 95% CI 1.1-58.3), and a decrease in daytime diastolic BP between day 0 and 4 of 10 mm Hg (OR 3.0; 95% CI 1.1-7.9) showed a significant relationship with poor outcome. Our findings suggest that admission BP values may not reliably reflect any impact of BP on stroke outcome. They also suggest a potential differential effect of BP manipulation: increasing or decreasing BP may be beneficial for patients with BP extremes in one direction, but detrimental for those with BP values in the opposite direction.

Adult↗

PubMed2001

Development and implementation of an EPR: how to encourage the user.

This paper reports on the role users played in the design and development of an electronic patient record. Two key users participated in the project team. All future users received questionnaires and a selection of them was interviewed. Before starting the development of the EPR, the attitude of users towards electronic record keeping, their satisfaction with the paper clinical records, their knowledge of computers, and their needs and expectations of computer applications in health care were measured by means of a questionnaire. The results of the questionnaire were supplemented with in-depth interviews. Users had a neutral attitude towards electronic record keeping. They were more positive about data entry of the paper records than data retrieval. During the development phase, but prior to the implementation of the EPR, a second questionnaire measured satisfaction with the paper records. Satisfaction appeared to be related to self-rated computer experience. Inexperienced computer users tended to be more positive about the paper records. In general, respondents did not have many expectations about electronic record keeping. A second series of interviews zoomed in on the expectations users had. Except for more concise reporting no beneficial effects of electronic record keeping were expected.

Adult↗

PubMed2001

Compensatory mechanisms enhance hippocampal acetylcholine release in transgenic mice expressing human acetylcholinesterase.

Central cholinergic neurotransmission was studied in learning-impaired transgenic mice expressing human acetylcholinesterase (hAChE-Tg). Total catalytic activity of AChE was approximately twofold higher in synaptosomes from hippocampus, striatum and cortex of hAChE-Tg mice as compared with controls (FVB/N mice). Extracellular acetylcholine (ACh) levels in the hippocampus, monitored by microdialysis in the absence or presence of 10(-8)-10(-3) M neostigmine in the perfusion fluid, were indistinguishable in freely moving control and hAChE-Tg mice. Muscarinic receptor functions were unchanged as indicated by similar effects of scopolamine on ACh release and of carbachol on inositol phosphate formation. However, when the mice were anaesthetized with halothane (0.8 vol. %), hippocampal ACh reached significantly lower levels in AChE-Tg mice as compared with controls. Also, the high-affinity choline uptake (HACU) in hippocampal synaptosomes from awake hAChE-Tg mice was accelerated but was reduced by halothane anaesthesia. Moreover, hAChE-Tg mice displayed increased motor activity in novel but not in familiar environment and presented reduced anxiety in the elevated plus-maze test. Systemic application of a low dose of physostigmine (100 microgram/kg i.p.) normalized all of the enhanced parameters in hAChE-Tg mice: spontaneous motor activity, hippocampal ACh efflux and hippocampal HACU, attributing these parameters to the hypocholinergic state due to excessive AChE activity. We conclude that, in hAChE-Tg mice, hippocampal ACh release is up-regulated in response to external stimuli thereby facilitating cholinergic neurotransmission. Such compensatory phenomena most likely play important roles in counteracting functional deficits in mammals with central cholinergic dysfunctions.

Acetylcholine↗

PubMed2001

A dose-response relation of headers and concussions with cognitive impairment in professional soccer players.

The purpose of this study was to determine the effects of headers and concussions on cognitive impairment in professional soccer players. A group of 84 active professional soccer players from several premier league soccer clubs underwent neuropsychological evaluations. The dose-response relation between the number of headers in one professional season and the number of soccer-related concussions on cognitive functioning was investigated. It was found that the number of headers in one season was related to poorer results on tests measuring focused attention and visual/verbal memory. Soccer-related concussions were related to poorer results on tests measuring sustained attention and visuoperceptual processing. The findings suggest that headers as well as concussions separately contribute to cognitive impairment.

Adult↗