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Biomedical subjects

J Stam

Publications and source records attributed to J Stam.

At least 37 records · Page 2Linked to original sources
PubMed1999

Spinal xanthomatosis: a variant of cerebrotendinous xanthomatosis.

We describe seven Dutch patients from six families with a slowly progressive, mainly spinal cord syndrome that remained for many years the sole expression of cerebrotendinous xanthomatosis (CTX). MRI demonstrated white matter abnormalities in the lateral and dorsal columns of the spinal cord. Post-mortem examination of one of the patients showed extensive myelin loss in these columns. An array of genotypes was found in these patients. We conclude that 'spinal xanthomatosis' is a clinical and radiological separate entity of CTX that should be included in the differential diagnosis of 'chronic myelopathy'.

Adult↗
PubMed1999

Randomized, placebo-controlled trial of anticoagulant treatment with low-molecular-weight heparin for cerebral sinus thrombosis.

BACKGROUND AND PURPOSE: Treatment of cerebral sinus thrombosis with heparin is controversial. We conducted a double-blind, placebo-controlled multicenter trial to examine whether anticoagulant treatment improves outcome in patients with sinus thrombosis. METHODS: Patients were randomized between body weight-adjusted subcutaneous nadroparin (180 anti-factor Xa units/kg per 24 hours) and matching placebo for 3 weeks (double-blind part of trial), followed by 3 months of oral anticoagulants for patients allocated nadroparin (open part). Patients with cerebral hemorrhage caused by sinus thrombosis were also included. RESULTS: Sixty patients were enrolled, and none were lost to follow-up. In 1 patient the diagnosis proved wrong after randomization. After 3 weeks, 6 of 30 patients (20%) in the nadroparin group and 7 of 29 patients (24%) in the placebo group had a poor outcome, defined as death or Barthel Index score of <15 (risk difference, -4%; 95% CI, -25 to 17%; NS). After 12 weeks, 4 of 30 patients (13%) in the nadroparin group and 6 of 29 (21%) in the placebo group had a poor outcome, defined as death or Oxford Handicap Score of >/=3 (risk difference, -7%; 95% CI, -26% to 12%; NS). There were no new symptomatic cerebral hemorrhages. One patient in the nadroparin group had a major gastrointestinal hemorrhage, and 1 patient in the placebo group died from clinically suspected pulmonary embolism. CONCLUSIONS: Patients with cerebral sinus thrombosis treated with anticoagulants (low-molecular-weight heparin followed by oral anticoagulation) had a favorable outcome more often than controls, but the difference was not statistically significant. Anticoagulation proved to be safe, even in patients with cerebral hemorrhage.

Adolescent↗
PubMed1998

Case-control study of risk of cerebral sinus thrombosis in oral contraceptive users and in [correction of who are] carriers of hereditary prothrombotic conditions. The Cerebral Venous Sinus Thrombosis Study Group.

OBJECTIVE: To investigate whether users of oral contraceptives and in [corrected] carriers of a hereditary prothrombotic condition (factor V Leiden mutation, protein C, S, or antithrombin deficiency) have an increased risk of cerebral sinus thrombosis. DESIGN: Comparison of a prospective series of cases of cerebral sinus thrombosis with population data. SETTING: Neurological teaching hospitals from different regions in the Netherlands (cases) and a representative sample of the non-institutionalised Dutch population (controls). SUBJECTS: 40 women aged 18-54 years with cerebral sinus thrombosis (cases) and 2248 women aged 18-49 years (controls). MAIN OUTCOME MEASURE: Current use of oral contraceptives at the time of the thrombosis (cases) or at the time of the questionnaire (controls). Prevalences of a hereditary prothrombotic condition in patients and in the population with odds ratios. RESULTS: 34 of 40 (85%) women with cerebral sinus thrombosis used oral contraceptives, versus 1007 of 2248 (45%) of the control women; the age adjusted odds ratio was 13 (95% confidence interval 5 to 37). Seven of 36 patients (19%) had a prothrombotic deficiency, versus 7% expected in the population; this corresponds to a threefold to fourfold increase in risk. In women who used oral contraceptives and also carried a prothrombotic defect, the odds ratio for cerebral sinus thrombosis was about 30 relative to women who had neither risk factor. CONCLUSION: The use of oral contraceptives and being a carrier of a hereditary prothrombotic condition increase the risk of and interact in a multiplicative way in the development of cerebral sinus thrombosis.

Adolescent↗
PubMed1998

Silent intracerebral microhemorrhages in patients with ischemic stroke. Amsterdam Vascular Medicine Group.

We compared the frequencies of signs of old intracerebral hemorrhages on brain magnetic resonance imaging scans in 66 patients with ischemic stroke, 69 with myocardial infarction, and 86 with peripheral arterial disease (a total of 221 patients). Magnetic resonance imaging scans were independently assessed by two investigators without knowledge of clinical or laboratory data. In 31 patients (14%) we found local cerebral hemosiderin deposits. In 24 patients they were clinically silent. Hemosiderin deposits were significantly more frequent in patients with ischemic stroke (26%) than in patients with myocardial infarction (4%) or peripheral arterial disease (13%). Hemosiderin deposits were associated with cerebral white matter lesions (odds ratio, 5.3; 95% confidence interval, 2.5-12.4). The odds ratios were higher in patients with severe cerebral white matter lesions. Our findings support the hypothesis that cerebral vessels of patients with ischemic stroke are more prone to rupture than those of patients with other manifestations of atherosclerotic disease, which may explain the higher incidence of intracerebral hemorrhages when these patients are treated with oral anticoagulants. The microhemorrhages were associated with cerebral white matter lesions, which suggests that they are another manifestation of cerebral small-vessel disease.

Aged↗
PubMed1998

Involvement of amino acid residues 423-429 of human protein S in binding to C4b-binding protein.

Human protein S binds to C4b-binding protein (C4BP) both in plasma and in a system using purified proteins. Amino acid residues 420-434 of the first disulfide loop of the sex hormone binding globulinlike domain of protein S are involved in the interaction of protein S with C4BP. To define the involvement of specific polar amino acids within residues 420-434, we studied in parallel synthetic protein S peptides and recombinant protein S variants containing the same amino acid replacements, K423E, E424K, Q427E and K429E. Synthetic peptide analogs of peptide PSP-420 (residues 420-434) were assayed for binding C4BP and as inhibitors of complex formation. The PSP-420 peptide and the analogous peptide with the substitution E424K, but not the peptides containing the substitutions K423E and K429E, were able to bind C4BP. Recombinant proteins with mutations of K423E, Q427E and K429E showed reduced affinity for C4BP compared to plasma protein S, recombinant wild type protein S, or E424K-protein S. These results suggest that Lys-423, Gln-427 and Lys-429 of protein S are important for normal binding to C4BP. The anti-protein S monoclonal antibody LJ-56, raised against peptide PSP-420, recognizes only free protein S and inhibits complex formation with C4BP. Antibody LJ-56 recognized the E424K and Q427E peptides but not the K423E or K429E peptides. Similarly, the E424K and Q427E protein S mutants were recognized by LJ-56, whereas the K423E and K429E protein S mutants were not recognized. This suggests that both in the peptide PSP-420 and in protein S, Lys-423 and Lys-429 significantly contribute to binding to antibody LJ-56. These results demonstrate that protein S residues 423, 427 and 429, but not residue 424, are involved in binding to both the antibody LJ-56 and to C4BP. When peptides PSP 420 and SL-6 (residues 447-460) with carboxyterminal amide or carboxylate moieties were compared to their ability to inhibit C4BP-protein S complexation, PSP-420-amide was the most potent. This finding together with the other results described here supports the hypothesis that the residues 420 and 434 in protein S provides a major binding site for C4BP.

Amino Acid Sequence↗
PubMed1998

Disequilibrium in patients with atherosclerosis: relevance of pontine ischemic rarefaction. Amsterdam Vascular Medicine Group.

OBJECTIVE: To examine the clinical relevance of isolated pontine hyperintense lesions (PHLs) on MRI in patients with atherosclerosis. METHODS: Seventeen atherosclerotic patients with isolated PHL on MRI were compared with 17 patients without PHL and were matched for age, sex, and initial manifestation of atherosclerosis. Subjects and observer were blinded to the MRI findings. We assessed symptoms, impairment, and disability with a structured interview and neurologic examination as well as disability scales. RESULTS: On all items, patients with PHL scored worse than did their controls. We found the largest differences in frequencies of symptoms of disequilibrium, difficulties with speech or swallowing, the Timed Walking Test, and the body care and movement subscale of the Sickness Impact Profile. Except for disequilibrium (p = 0.04), these differences did not reach statistical significance. Abnormal tandem-walking tests were more frequent in patients than they were in controls. Pyramidal signs were equally distributed. CONCLUSIONS: We propose PHL as a cause of symptoms of disequilibrium in patients with atherosclerosis. Symptoms are probably elicited by dysfunction of the corticopontine fibers, the pontocerebellar fibers, or the pontine nuclei.

Aged↗
PubMed1997

T2-weighted hyperintense MRI lesions in the pons in patients with atherosclerosis. Amsterdam Vascular Medicine Group.

BACKGROUND AND PURPOSE: Pontine hyperintense lesions (PHL) on T2-weighted MRI have been recognized recently. Histopathological findings resemble periventricular leukoaraiosis, and a vascular etiology has been suggested. We studied the frequency and the associated factors of PHL in patients with symptomatic atherosclerosis. METHODS: Two independent observers assessed brain MRIs in a prospective cohort of patients with symptomatic atherosclerosis. Only patients in whom both observers scored PHL on T2- and proton density-weighted images, but not on T1-weighted images, were considered to have the lesion. RESULTS: We studied 229 patients 31% presenting with ischemic stroke, 31% with myocardial infarction, and 38% with peripheral artery disease. Both observers scored PHL in 23% of all patients. Patients with PHL were significantly older and had more lacunar infarcts and periventricular leukoaraiosis than patients without PHL. There were more women, more hypercholesterolemic and diabetic patients, and more cortical infarcts on MRI (P = NS). After logistic regression the presence of leukoaraiosis (odds ratio, 2.4; 95% confidence interval, 1.6 to 3.4) and lacunar infarcts (odds ratio, 2.2, 95% confidence interval, 1.5 to 3.1) remained independently associated with PHL. PHL was more common in patients with ischemic strokes (39%) than in patients with myocardial infarctions (11%) or peripheral artery disease (19%) (P < .001). CONCLUSIONS: We found that PHL on T2- and proton density-weighted MR images are often found in patients with symptomatic atherosclerosis. The association with periventricular leukoaraiosis and lacunar infarcts suggests that PHL is a variant of leukoaraiosis, with possibly the same pathophysiology. The clinical symptoms and consequences of PHL, however, are not yet clear.

Age Distribution↗
PubMed1996

[Consensus on diagnosis and treatment of the lumbosacral radicular syndrome. Dutch Society for Neurology].

A consensus development meeting concerning the treatment of lumbosacral radicular syndrome (LRS) by entrapment by a herniated disc or spinal stenosis was held on June 9th, 1995. It was observed that there is a lack of good evidence on many aspects of diagnosis and treatment of LRS. Agreement was reached on the thesis that the natural course of LRS is often benign. Diagnosis and treatment can usually be left to the primary care physician. Specialist consultation and ancillary investigations are only needed if an operation is indicated or in case of persistent diagnostic uncertainty. If imaging is needed MRI is preferred to CT or myelography. MRI is highly sensitive, but less specific, and may thus give false-positive results. Neurophysiologic testing may be informative in selected cases. Plain spinal X-rays are not useful in most cases. The traditional non-invasive treatments (such as bedrest, traction, physiotherapy, spinal manipulation) are not based upon convincing scientific evidence. Diagnostic imaging and invasive treatment should be considered in patients with a severe LRS that does not improve within a 4 to 8 week period. Both discectomy and chemonucleolysis are effective treatments. The principal indication is incapacitating radicular pain. There is no sound evidence that the prognosis of paresis is improved by operation. A cauda equina syndrome urgently needs surgical treatment. The efficacy of percutaneous interventions (nucleotomy, laser therapy) has not been proven. There are no strategies for the primary or secondary prevention of LRS that have demonstrated their efficacy. Psychological, social and financial factors probably contribute significantly to the occurrence of persisting symptoms after a LRS. Advice not to work after treatment for LRS may impede rehabilitation.

Diagnostic Imaging↗
PubMed1996

Thunderclap headache as first symptom of cerebral venous sinus thrombosis. CVST Study Group.

BACKGROUND: Thunderclap headache raises the suspicion of subarachnoid haemorrhage, and it is not generally recognised as a symptom of cerebral venous sinus thrombosis (CVST). We describe ten patients who presented with thunderclap headache mimicking subarachnoid haemorrhage, who appeared to have CVST. METHODS: Medical histories of 71 patients who had CVST between 1992 and 1996 were collected. 48 of these took part in a randomised trial of treatment for CVST. The diagnosis was confirmed by conventional angiography or magnetic resonance imaging and angiography in all patients. FINDINGS: In all ten patients who presented with thunderclap headache, characteristics of the headache and clinical signs and symptoms were clinically indistinguishable from those of subarachnoid haemorrhage. Computed tomography at admission was interpreted as normal in five patients (one with single-dose contrast), as subarachnoid haemorrhage in three, and as multiple intracranial haemorrhages in the remaining patients (one with single-dose contrast). Cerebrospinal fluid (CSF) analysis was done in six patients, and showed erythrocytes and bilirubin in one. CSF pressure was high in the only patient for whom it was measured. INTERPRETATION: The best initial investigation in patients with thunderclap headache is emergency computed tomography. If no abnormality is detected, lumbar puncture should be done after at least 12 h (to detect or exclude subarachnoid haemorrhage). CSF pressure should be measured. If the CSF pressure is high or if a headache of unknown origin persists, the diagnosis of CVST should be considered.

Acute Disease↗
PubMed1996

[Computer-assisted education in problem-solving in neurology; a randomized educational study].

OBJECTIVE: To determine the effect of computer-based medical teaching (CBMT) as a supplementary method to teach clinical problem-solving during the clerkship in neurology. DESIGN: Randomized controlled blinded study. SETTING: Academic Medical Centre, Amsterdam, the Netherlands. METHOD: 103 Students were assigned at random to a group with access to CBMT and a control group. CBMT consisted of 20 computer-simulated patients with neurological diseases, and was permanently available during five weeks to students in the CBMT group. The ability to recognize and solve neurological problems was assessed with two free-response tests, scored by two blinded observers. RESULTS: The CBMT students scored significantly better on the test related to the CBMT cases (mean score 7.5 on a zero to 10 point scale; control group 6.2; p < 0.001). There was no significant difference on the control test not related to the problems practised with CBMT. CONCLUSION: CBMT can be an effective method for teaching clinical problem-solving, when used as a supplementary teaching facility during a clinical clerkship. The increased ability to solve problems learned by CBMT had no demonstrable effect on the performance with other neurological problems.

Computer-Assisted Instruction↗
PubMed1995

[Thrombosis of the cerebral veins and sinuses in 62 patients].

OBJECTIVE: Analysis of signs, symptoms, course and treatment of patients with cerebral venous and sinus thrombosis (CVST). DESIGN: Retrospective study. SETTING: Neurological departments of Dutch teaching hospitals. METHOD: Analysis of data of patients admitted to the neurological wards of nine teaching hospitals, diagnosed from 1970 to 1990. All patients with a clinical diagnosis of CVST, confirmed by X-ray angiography, magnetic resonance imaging, surgery or autopsy were included. Patients with cavernous sinus thrombosis were excluded. The clinical condition of patients after 3 months was scored on a 4-point scale. RESULTS: Of 93 patients 62 fulfilled the inclusion criteria. Three months after the diagnosis 41 patients (66%) had recovered, 10 patients (16%) were seriously disabled, 11 patients (18%) had died. Factors associated with a poor outcome were coma (relative risk 3.5) and hemiparesis (relative risk 2.3) at the time of diagnosis. Signs of cerebral haemorrhage or infarction (by computed X-ray tomography) were associated with disability or death. Anticoagulant treatment was not significantly associated with a better or poorer outcome in these patients. CONCLUSION: This study confirms the variations in causes, clinical presentation, natural history, and treatment of CVST. No conclusion could be drawn about the effect of anticoagulant treatment.

Anticoagulants↗
PubMed1995

Biochemical parameters in BAL of sarcoisosis.

UNLABELLED: Sarcoidosis can be presented to the physician as an active or silent disorder, which may resolve or lead to pulmonary fibrosis. Various serum or bronchoalveolar lavage fluid (BAL) markers have been suggested when trying to find one marker or a combination of markers which could be representative of the disease. The aim of the study was to evaluate a number of biochemical markers in comparison to cellular parameters in BAL of 45 patients with active or inactive sarcoidosis, as well as in 44 patients with other disorders and of 10 healthy volunteers. Moreover, in order to get insight into ACE activity in different compartments, ACE values in BAL and serum were compared. In active sarcoidosis BAL-procollagen-III-peptide was significantly increased in contrast to the very low values in inactive disease. In healthy volunteers procollagen-III-peptide levels were below the detection limit. In BAL no significant differences were found for beta-2-microglobulin, hyaluronan or ACE. Laminin in BAL was not detectable. Serum ACE, significantly enhanced in sarcoidosis, was not discriminative between active and inactive disease. IN CONCLUSION: only procollagen-III-peptide in BAL was found to discriminate between active and inactive disease. Besides cell differentiation and T-helper/suppressor cell (CD4/CD8) ratio in BAL, no further biochemical parameters pointing to disease or activity of disease were found.

Adult↗
PubMed1994

Monoclonal antibodies to immunodominant and neutralizing domains of the envelope surface protein of feline immunodeficiency virus.

Hybridomas secreting monoclonal antibodies (MAbs) specific for the surface protein (SU) of feline immunodeficiency virus were generated. Four MAbs were obtained which could be assigned to two groups based on their neutralization and competition behaviour. Using SU protein fragments expressed in Escherichia coli the antigenic site recognized by one of the MAbs (2H11) could be mapped to the c terminus. The neutralizing MAb 1E1 did not bind to any of the SU protein fragments and was directed to a conformational epitope. Binding of the MAb 1E1 to native SU protein could be blocked with a rabbit serum raised against the SU3 fragment (amino acids 361 to 445). These data indicate that at least part of the epitope is located on this SU3 domain. In competition experiments most sera of naturally infected cats were able to inhibit binding of the MAbs. This shows the conserved and immunodominant nature of the epitopes involved.

Animals↗