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Biomedical subjects

M Vermeulen

Publications and source records attributed to M Vermeulen.

At least 109 records · Page 6Linked to original sources
PubMed1995

Treatment of multifocal motor neuropathy with high dose intravenous immunoglobulins: a double blind, placebo controlled study.

The effect of high dose intravenous immunoglobulin (IVIg) treatment was studied in six patients with multifocal motor neuropathy (MMN). All patients responded to treatment (0.4 g/kg for five consecutive days) in an open trial. The effect of IVIg treatment was confirmed for each patient in a single patient, double blind, placebo controlled trial. Four patients received two IVIg treatments and two placebo treatments, and two patients received one IVIg and one placebo treatment in a randomised order. Five out of six patients responded to IVIg but not to placebo. One patient responded to IVIg in the same manner as to placebo treatment. Thus IVIg treatment can lead to improvement of muscle strength in patients with MMN.

Adult↗
PubMed1995

Diagnostic value of GM1 antibodies in motor neuron disorders and neuropathies: a meta-analysis.

We performed a meta-analysis on the diagnostic value of IgM anti-GM1 antibodies. The reported frequencies of IgM anti-GM1 antibodies ranged from 0 to 100% for patients with multifocal motor neuropathy (MMN), from 0 to 33% in the Guillain-Barré syndrome, from 0 to 65% in amyotrophic lateral sclerosis (ALS), from 0 to 77% in chronic inflammatory demyelinating neuropathy, and from 0 to 81% in lower motor neuron disease (LMND). However, using funnel graphs and a chi-square test we determined that the method of ELISA was the most important factor explaining these differences. After allowing for two factors--the use of detergent and the duration and temperature of serum incubation-studies became homogeneous in all but the LMND group of method A (no detergent, duration of serum incubation 5 hours) and the ALS group of method B (no detergent, duration of serum incubation at least 12 hours [overnight]). Since the anti-GM1 antibody assay serves to confirm clinical suspicion of MMN rather than to exclude the disease, specificity is more important than sensitivity. ELISA methods that do not use detergent and that incubate serum overnight resulted in a specificity of 90% and sensitivity of 38% in the comparison of MMN and LMND. With these values we calculated incremental ruling-in and ruling-out gain curves. Prior probabilities between 20 and 60% for having MMN changed to post-test probabilities between 50 and 85%, which is of clinical importance. In conclusion, ELISA is a useful diagnostic test to demonstrate IgM anti-GM1 antibodies provided the methods do not use detergent and do incubate serum overnight.

Antibodies↗
PubMed1994

[Course of chronic idiopathic polyneuropathy during middle age and older: 2-year follow-up study].

OBJECTIVE: To study the clinical features and natural course of idiopathic polyneuropathy. DESIGN: Prognostic and descriptive cohort study. SETTING: University Hospital, Utrecht, the Netherlands. METHOD: 75 patients (46 men, 29 women) with a mean age of 56.5 years at onset of symptoms were clinically investigated during two years. RESULTS: The features of chronic idiopathic polyneuropathy were heterogeneous. Clinically, 44 patients had a sensorimotor, 29 patients a sensory and 2 patients a motor polyneuropathy. Electrophysiological and nerve biopsy studies were compatible with an axonal polyneuropathy. The overall clinical course was slowly progressive. None of the patients became severely disabled. After one year of follow up one patient proved to have a hereditary neuropathy. In the other 74 patients no cause for the polyneuropathy was found even after 2 years of follow-up. CONCLUSION: Chronic idiopathic polyneuropathy is a heterogeneous entity, leading to only slight disability. The neuropathy is due to axonal degeneration.

Age Factors↗
PubMed1994

Anti-GM1 antibodies in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) treated with intravenous immunoglobulin (IVIg).

Patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and with a chronic polyneuropathy (non-CIDP) were studied for the presence of anti-GM1 antibodies. In pretreatment sera of CIDP patients, we found IgG anti-GM1 antibodies in 23%, IgM in 7%, and IgA in 14%. Predominantly motor involvement was associated with IgG and IgM anti-GM1 antibodies in CIDP patients (P = 0.002). Improvement after intravenous immunoglobulin (IVIg) therapy was not associated with anti-GM1 antibody titer before or after treatment. Anti-GM1 antibody titers before onset of treatment was not related to poor clinical outcome, although large clinical improvements after IVIg therapy were observed less often (P = 0.057) in patients with high titer anti-GM1 antibodies before treatment.

Action Potentials↗
PubMed1994

Prolongation by captopril of action potential duration in the normal and hypertrophied rat ventricle: direct action or inhibition of the local angiotensin converting enzyme?

OBJECTIVE: The aims were: (1) to study the acute effects of captopril on the action potential characteristics of ventricular fibres from the normal rat, (2) to compare the effects of captopril with those of perindoprilat, a non-thiol angiotensin I converting enzyme (ACE) inhibitor, (3) to determine the electrophysiological properties of the peptide substrates of converting enzyme, bradykinin and angiotensin I, and (4) to investigate whether the effects of captopril occurring in the healthy heart also occur in two models of ventricular hypertrophy. METHODS: Action potentials were recorded with the standard glass microelectrode technique in right ventricular preparations excised from rat hearts and superfused under baseline conditions and with drug containing or peptide containing Tyrode solution. Ventricular hypertrophy was induced in response to hypertension (unilaterally nephrectomised, DOCA-salt model) or 4 week old left ventricular infarction. RESULTS: In preparations from normal rat hearts, captopril increased action potential duration in a concentration dependent fashion [EC50 = 3.5 x 10(-8) M; maximum effect = 44(SEM 5.1)% prolongation at 10(-5) M for action potential duration at 90% repolarisation, APD90]. Perindoprilat similarly caused a dose dependent increase in action potential duration, but with 100 times greater potency [EC50 = 3.1 x 10(-10) M; maximum effect = 71(11)% prolongation at 10(-5) M for APD90]. SQ 14,534, a stereoisomer of captopril with one hundredth the ACE inhibitor potency, had no significant effect on action potential duration at 10(-5) M. Angiotensin I and bradykinin caused concentration dependent prolongation of action potential, but angiotensin II (10(-6) M) had no effect. Captopril (10(-5) M) had no significant effect in the hypertrophied right ventricle from DOCA-salt hypertensive rats, but significantly increased APD90 [39(4.9)%] in right ventricular preparations from rats with 4 week old anterior left ventricular infarction. CONCLUSIONS: In the rat, captopril prolongs action potential duration, an effect possibly due to local accumulation of bradykinin and angiotensin I.

Action Potentials↗
PubMed1994

Definition of initial grading, specific events, and overall outcome in patients with aneurysmal subarachnoid hemorrhage. A survey.

BACKGROUND AND PURPOSE: Scientific communication in medicine can be effective only if reports are based on unequivocal criteria for clinical conditions or specific diagnoses. METHODS: We reviewed all articles about subarachnoid hemorrhage published in nine neurosurgical or neurological journals from 1985 through 1992 and assessed the presence and the precision of definitions used for reporting the initial grade, the specific complications of rebleeding, delayed cerebral ischemia, and hydrocephalus, and the overall outcome. We identified 184 articles reporting direct observations in at least 10 patients on one or more of these conditions. RESULTS: Of 161 articles reporting the initial condition, only 19% used an unequivocal grading system (World Federation of Neurological Surgeons Scale or Glasgow Coma Scale); this proportion did not increase after 1988, when the World Federation of Neurological Surgeons Scale was introduced. The specific outcome events of rebleeding, ischemia, and hydrocephalus (283 instances) were sufficiently defined in only 31% of instances, incompletely in 22%, and not at all in 47%. The proportions were similar when the results were analyzed according to the type of complication, the year of publication, or per study. The four exclusively neurosurgical journals featured suitable definitions for any of the three outcome events in 20% of 209 instances, whereas the five mainly neurological journals published fewer articles about subarachnoid hemorrhage (74 instances of outcome events) but more often with precise criteria (65%). Overall outcome was adequately reported in 63% of all articles, with an increase over the years (54% in 1985 through 1988, 71% in 1989 through 1992). CONCLUSIONS: Reports about subarachnoid hemorrhage require closer scrutiny before publication to ascertain whether the conclusions about specific outcome events are based on unequivocal criteria.

Bias↗
PubMed1994

Predictive factors for deterioration from hydrocephalus after subarachnoid hemorrhage.

We studied the predictive factors for deterioration from hydrocephalus that developed during the first 28 days after admission in 660 patients following aneurysmal subarachnoid hemorrhage (SAH). Deterioration from hydrocephalus was defined as deterioration of consciousness with no detectable cause other than hydrocephalus confirmed by a repeat CT with a bicaudate index exceeding the 95th percentile for age. Deterioration from hydrocephalus occurred in 143 (22%) of the 660 patients. The variables included in the analysis were sex, age, loss of consciousness at ictus, sum score on the Glasgow Coma Scale on admission, sum score of cisternal blood and presence of ventricular blood on initial CT, hydrocephalus on initial CT, confirmed aneurysm, rebleeding, delayed cerebral ischemia, and treatment with tranexamic acid for 4 (short-term treatment) or 28 (long-term treatment) days. In a multivariate analysis with the Cox proportional hazards model incorporating fixed and time-dependent covariates, sum score of cisternal blood on initial CT (hazard ratio 3.15, p < 0.000001), presence of ventricular blood on initial CT (hazard ratio 1.66, p = 0.004), hydrocephalus on initial CT (hazard ratio 3.37, p < 0.000001), and long-term treatment with tranexamic acid (hazard ratio 2.40, p < 0.000001) were significantly related with the development of hydrocephalus. We conclude that a high amount of blood after SAH and delay of the resorption of cisternal and ventricular blood caused by long-term treatment with tranexamic acid increases the risk of deterioration from hydrocephalus after SAH.

Adult↗
PubMed1994

Transient ischemic attacks, carotid stenosis, and an incidental intracranial aneurysm. A decision analysis.

Three patients with transient ischemic attacks (TIAs), a stenotic or ulcerating carotid lesion, and an unruptured aneurysm are discussed. Decision analysis is used in comparing treatment strategies for each patient: clipping of the aneurysm, endarterectomy, or both, with or without platelet aggregation inhibitors. Bayesian sensitivity analysis with Monte Carlo simulation is used to estimate 95% confidence limits for the difference in discounted quality-adjusted life expectancy between the treatment strategies. Platelet-inhibiting therapy is indicated for all three patients, despite the increased risk of complications from subarachnoid hemorrhage. Carotid endarterectomy cannot be recommended for any of the three patients. With regard to aneurysm surgery, a toss-up exists in one patient; in another, the aneurysm should be clipped; and in one, the decision depends on the probability that the TIAs originate from the aneurysm. Guidelines for the management of similar patients are given. For patients with TIAs, a moderate carotid stenosis, and an intracranial aneurysm that does not seem to be related to the symptoms, neither clipping of the aneurysm nor endarterectomy can be recommended with confidence; however, when the intracranial aneurysm is just as likely to be the source of the TIAs as not, clipping is recommended up to the age of 70, when the surgical risks are moderately high.

Aged↗
PubMed1993

Spontaneous recovery from the Guillain-Barré syndrome is associated with anti-idiotypic antibodies recognizing a cross-reactive idiotype on anti-neuroblastoma cell line antibodies.

The presence of suppressive antibody activity in sera from patients spontaneously recovered from the Guillain-Barré syndrome was investigated by analyzing the ability of postrecovery serum to inhibit anti-neuroblastoma cell line antibody binding in sera from seven patients in the prerecovery phase or with a chronic form of the disease. All 12 recovered patients analyzed were found to have inhibitory IgG antibodies in their postrecovery sera, of which the F(ab')2 fragments mediated the inhibitory effect. The pattern of inhibition suggests that about half of the patients share cross-reactive idiotypes of high affinity. The efficiency of the inhibition mediated by anti-idiotypic antibodies in spontaneously recovered patients was twice as high as that mediated by anti-idiotypes present in therapeutical preparations of polyclonal immunoglobulins for intravenous use (IVIG). Affinity chromatography of IVIG and serum from a recovered Guillain-Barré syndrome patient on autoantibody-containing F(ab')2 fragments revealed, first, that inhibitory anti-idiotypic antibodies are specifically retained on autoantibodies and, second, that these antibodies constitute less than 1% of the total IgG antibody content.

Antibodies↗
PubMed1993

Neonatal pinealectomy impairs murine antibody-dependent cellular cytotoxicity.

The pineal gland, through its principal hormone melatonin, is able to modulate different immune functions. We have previously demonstrated that exogenous melatonin induces a significant enhancement of murine antibody-dependent cellular cytotoxicity (ADCC). In order to determine whether the pineal gland plays a physiological role in ADCC regulation, we studied the influence of neonatal pinealectomy on this activity. The results presented here indicate that ablation of the pineal gland during the first week of life significantly reduces ADCC levels in adult mice. This impairment appears around 60 days of age, suggesting that sexual hormones may be involved in the pineal effect. Moreover, the administration of melatonin to pinealectomized mice restores ADCC levels regardless of the hour and seasonal time of injection. On the basis of the data reported here, a physiological regulation of ADCC by the pineal gland can be assumed.

Animals↗
PubMed1993

Seasonal variations in antibody-dependent cellular cytotoxicity regulation by melatonin.

Data collected over a period of 4 years show that melatonin (two daily i.v. injections of 0.1 mg/kg body wt. given at 16:00 h) was able to enhance antibody-dependent cellular cytotoxicity (ADCC) in summer, but not in winter. Dose-response curves carried out in January, May, July, and October suggest that the seasonal effects reported are related to differences in the sensitivity of mice to melatonin during the course of the year. These results show seasonal variations in the immune modulatory action of melatonin.

Animals↗
PubMed1993

Intravenous immunoglobulin treatment in patients with chronic inflammatory demyelinating polyneuropathy: a double blind, placebo controlled study.

Patients with a clinical diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) were randomised in a double-blind, placebo-controlled multicentre trial to investigate whether high-dose intravenous immunoglobulin treatment (IVIg) for 5 consecutive days has a beneficial effect. Fifteen patients were randomised to IVIg and 13 to placebo. In the IVIg treatment group 4 patients improved and 3 patients in the placebo group. The degree of improvement of the patients in the IVIg treatment group was no different from the patients in the placebo group. Electrophysiological studies did not show significant differences between the groups. Since a previously performed cross-over trial showed that a selected group of CIDP patients responded better to IVIg than to placebo, it is concluded that we need better criteria to select CIDP patients for treatment with IVIg.

Chronic Disease↗
PubMed1993

Chronic idiopathic polyneuropathy presenting in middle or old age: a clinical and electrophysiological study of 75 patients.

The clinical and electrophysiological features were prospectively studied of 75 patients (46 men and 29 women) with chronic polyneuropathy presenting in middle or old age in whom a diagnosis could not be made even after extensive evaluation and a follow up of six months. The mean age at the onset of symptoms was 56.5 years. The clinical features of chronic idiopathic polyneuropathy are heterogeneous. On clinical grounds 44 patients had a sensorimotor, 29 patients a sensory, and two patients a motor polyneuropathy. The overall clinical course in chronic idiopathic polyneuropathy was slowly progressive. None of the patients became severely disabled. Electrophysiological and nerve biopsy studies were compatible with an axonal polyneuropathy. Antibodies against myelin associated glycoprotein, gangliosides, and sulphatides were assessed in 70 patients and found to be negative.

Age of Onset↗