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Two major issues in clinical trials in stroke are the criteria used for the selection of patients expected to benefit from the proposed treatment, and the entry time of those patients. We surveyed 507 Belgian general practitioners (GPs) on their opinions on referral of stroke patients to hospital and also on their actual referral behaviour. The feasibility of a 6-hour entry time was included in the investigation. Stroke is considered to require an urgent response: 88% of GPs visited the patient immediately on concluding that such an event had occurred. The mean time between the onset of the first clinical symptoms and the arrival of the GP at the patient's residence was about 30 minutes. Within 6 h of the insult, 95% of the patients referred to hospital had been admitted. Information on the GP's most recent stroke patient revealed that 72.4% of these stroke patients were admitted to hospital. Patients referred to hospital were significantly younger, had a significantly more severe stroke, and were significantly more likely to have had a first stroke and to have lived independently before the insult than patients not admitted to hospital. We think that Belgian GPs need to change their referral behaviour with respect to stroke patients and refer more of those who have suffered more mildly. There is every reason to be optimistic about this re-education, since the patients whom GPs do refer to hospital are referred rapidly enough to profit from a possibly efficacious treatment.

The usefulness of non-contrast-enhanced, standardized magnetic resonance imaging for the longterm follow-up of MS patients was evaluated in a retrospective study in 36 patients with clinically definite MS. All had remitting-relapsing diseases courses. Sixteen patients remained clinically stable during follow-up. Mean duration of follow-up was 22 months (SD: 11). A mean number of 3 MRI examinations was performed in each of the patients (SD: 1). Subclinical evolution was detected in 56% of the stable patients, indicating that clinical data alone are insufficient to assess disease activity. The relapsing patients showed significantly more and larger changes on MRI than stable patients (P less than 0.001), indicating that MRI is well suited as a follow-up parameter in conjunction with clinical data. The time courses of these quantitative changes and of the qualitative changes of putative MS lesions on MRI are discussed. It is concluded that MRI is a good indicator of global disease activity in multiple sclerosis patients, which makes MRI very useful for the evaluation of therapeutic trials.

IgG1-secreting variants have been isolated from three different IgM-secreting hybridomas, in two instances following in vitro immunization. The method used was based on sequential sublining in combination with selection by an IgG1-specific two-site ELISA system employing two different IgG1-specific polyclonal antisera. Idiotypic identity between the IgG1 variants and their respective IgM parent was demonstrated using syngeneic anti-idiotypic antisera. The antigen binding specificity in the IgG1 variants was also conserved. Isolation of naturally occurring IgG1 switch variants from IgM-secreting hybridomas that are produced after in vivo immunization offers a solution to the major disadvantages associated with the generation of IgM hybridomas.

In a previous study we have shown that the sensitivity of magnetic resonance imaging (MRI) for the detection of multiple sclerosis (MS) lesions was improved significantly, especially in the infratentorial region, by use of an extensive standardized MRI-protocol consisting of sagittal T1, axial protondensity and axial T2, and sagittal protondensity and sagittal moderately T2-weighted images. The goal of the present study was to assess whether the clinical correlation of the visualized lesions had improved accordingly. Using a scoring system based on lesion dimensions, we compared 70 MRI examinations performed in 25 patients with definite MS, with the relevant clinical data as given by the Expanded Disability Status Scale (EDSS) and Functional System scale (FS). We found a significant correlation (r = 0.66, P = 0.0001) between the MRI score and the EDSS. Significant correlations also existed between MRI scores and cerebellar and brainstem FS scores. These correlations were consistently higher than those reported by other authors. We conclude that a standardized MRI examination, including sagittal protondensity and moderately T2-weighted images, should be performed in every MS patient. The improved clinical correlation could be of importance in follow-up studies when assessing the efficacity of therapy.

The relative value of two different MRI procedures for the assessment of infratentorial extension in multiple sclerosis (MS) was studied. Multislice spin-echo techniques were used overall. Procedure A consisted of parasagittal T1-weighted images (500/30) and axial T2-weighted images (2500/30, 2500/120). Procedure B consisted of parasagittal T2-weighted images (1600/35, 1600/90). In the parasagittal T2-weighted images clear visualization of MS lesions is achieved because signal intensities of CSF and normal nervous tissue are nearly identical. All images were performed with a 0.5 Tesla MR system. Data were obtained in 98 patients with definite (N = 30) or probable MS (N = 68). Areas with abnormal signal intensity in the infratentorial regions (brainstem, cerebellum, and/or cervical spinal cord) were identified in 44% of the patients with procedure A and in 64% with procedure B. The standard application of the combination of both procedures improves the sensitivity of the MR examination for the diagnosis of MS, the delineation of infratentorial lesions and the correlation between clinical and MR data without excessively increasing imaging time.

A new radioimmunoassay which is suitable for screening lymphocyte hybridoma cultures for monoclonal antibody production is described. Solid-phase antigen is first incubated with the sample, and secondly with soluble 125I-labeled antigen. When the sample contains multivalent specific antibody, the labeled antigen will be bound to the solid-phase antigen. Because no anti-immunoglobulin reagent is used as a second reagent, this type of radioimmunoassay offers several advantages, in particular for the production of monoclonal anti-idiotypic antibodies.

We report a large Belgian family with Charcot-Marie-Tooth disease (CMT) or hereditary motor and sensory neuropathy type I (HMSN-I). The pedigree consists of 5 generations with 350 family members comprising 42 patients. The disease is transmitted according to an autosomal dominant inheritance pattern. Several HMSN-I families have been reported to be closely linked to the Duffy blood group marker on chromosome 1. These families were designated HMSN-Ib families, opposed to the HMSN-Ia families which do not show evidence for such a linkage. Therefore we examined our family for the Duffy linkage relationship. We found no evidence for a strong linkage of the disease to the Duffy blood group locus, indicating that this family is of genetic subtype Ia.

Glial fibrillary acidic protein (GFAp), an intracellular protein specific to astrocytes of the central nervous system, was determined by 2-site immunoradiometric assay in amniotic fluid from 78 pregnancies with a normal, and 100 with an abnormal outcome. GFAp was not detectable in any of the normal pregnancies, but there were measurable, and so raised, levels in 23 out of 25 cases of anencephaly and 4 out of 7 cases of spina bifida, which therefore allowed prenatal diagnosis. GFAp was also increased in 4 of 6 cases of fetal intrauterine death, but not in other congenital malformations associated with elevated alphafetoprotein levels or abnormal acetylcholinesterase banding pattern, such as exomphalos, other gastrointestinal malformations or renal abnormalities. GFAp is therefore specific for diagnosing open neural tube defects. The determination of GFAp in amniotic fluid was slightly less efficient overall than AFP for the prenatal diagnosis of neural tube defects, but can be a useful ancillary test and has the advantage of specificity.

Simultaneous incubation of bovine adrenal medullary plasma membranes (PM) with chromaffin granules (CG) resulted in the release of the soluble granular content. The molecular mechanism of this process was studied with several monoclonal antibodies (mAb) raised against different plasma membrane components. Specific inhibition of the catecholamine secretion was obtained upon incubation with the monoclonal antibody UIA/NEU/VI B17. The corresponding antigen had an apparent molecular weight of 54000 Dalton. These results suggest a specific recognition between proteins located on the plasma membrane and chromaffin granule membrane, the interaction of which mediates exocytosis.

A two-site immunoradiometric assay for a brain specific protein (alpha-albumin or glial fibrillary acidic protein) is described which may be applied to other proteins. The assay variables studied are immunoadsorbent dilution, temperature, incubation times, reactivity of the labelled antibodies and effect of the washing. Each of these factors is optimalised, resulting in a sensitive, specific, reliable assay. The working range is 5--5000 ng/ml, the within-assay variance is 5%. No high dose hook effect is seen in this range. The method is applied for the measurement of alpha-albumin present in cerebrospinal fluid, nervous tissue extracts and cell cultures.