A clinical study of motor evoked potentials using a triple stimulation technique

Amplitudes of motor evoked potentials (MEPs) are usually much smaller than those of motor responses to maximal peripheral nerve stimulation, and show marked variation between normal subjects and from one stimulus to another. Consequently, amplitude measurements have low sensitivity to detect central motor conduction failures due to the broad range of normal values. Since these characteristics are mostly due to varying desynchronization of the descending action potentials, causing different degrees of phase cancellation, we applied the recently developed triple stimulation technique (TST) to study corticospinal conduction to 489 abductor digiti minimi muscles of 271 unselected patients referred for possible corticospinal dysfunction. The TST allows resynchronization of the MEP, and thereby a quantification of the proportion of motor units activated by the transcranial stimulus. TST results were compared with those of conventional MEPs. In 212 of 489 sides, abnormal TST responses suggested conduction failure of various degrees. By contrast, conventional MEPs detected conduction failures in only 77 of 489 sides. The TST was therefore 2.75 times more sensitive than conventional MEPs in disclosing corticospinal conduction failures. When the results of the TST and conventional MEPs were combined, 225 sides were abnormal: 145 sides showed central conduction failure, 13 sides central conduction slowing and 67 sides both conduction failure and slowing. It is concluded that the TST is a valuable addition to the study of MEPs, since it improves detection and gives quantitative information on central conduction failure, an abnormality which appears to be much more frequent than conduction slowing. This new technique will be useful in following the natural course and the benefit of treatments in disorders affecting central motor conductio

Optimization of the active absorber scheme for the protection of the Dispersion Suppressor

There are two main types of cold elements in IR7: quadrupole and dipole magnets (MQ and MB). According to predictions, these objects are to lose their superconducting properties if the spurious power densities reach about 1 and 5 mW/cm3, respectively. In order to protect these fragile components, 5 active absorbers (TCLA) were designed and a systematic study was launched to maximize the shielding efficiency of the absorber system for different configurations (locations and orientations). The TCLA's are identical to the secondary collimators (TCS), the only difference is found in the material of the jaw, which, initially, was set integrally to Cu (instead of C) and later included a small W insertion. This report summarizes the survey of cold element protection through TCLA insertion optimization

Ultrastructural changes in enterocytes in subjects with Hashimoto's thyroiditis

We have recently described1 mucosal ultrastructural impairments, such as height and thickness of microvilli, space between microvilli, and thickness of tight junctions, in non-coeliac type 1 diabetic patients after a preliminary report of an alteration in intestinal mucosal permeability (IP) evaluated by the lactulose/mannitol (LA/MA) test.2,3 Therefore, in the “aetiological” classification of autoimmunity based on initiating factors,4 the category of diet induced diseases could be expanded to include type 1 diabetes and, perhaps, other endocrine autoimmune diseases. Thyroiditis is the most frequently associated autoimmune endocrine disease with type 1 diabetes. Moreover, type 1 diabetes and Hashimoto thyroiditis present similar pathogenetic mechanisms of cellular damage, a cell mediated autoimmunity induced by Th1 cytokines. However, mucosal intestinal morphology and function have not yet been studied in autoimmune thyroiditis patients. Hence we investigated intestinal mucosal ultrastructural morphology and IP in a group of patients with autoimmune thyroiditis. The study was approved by the local ethics committee. Fourteen patients (12 females and 2 males; mean age 33.2 (SD 10.2) years) and 23 controls (12 females and 11 males; mean age 27.9 (SD 8.01) years) were enrolled into the study after giving written informed consent. The diagnosis of autoimmune thyroiditis was based on the following criteria: plasma autoantibody TPO positive at high titre and a typical thyroiditis ultrasound pattern. All patients were in euthyroidism (normal FT3, FT4, and TSH plasma levels without hormonal therapy). Mean duration of known disease was 5.2 (2.5) years. All patients were negative for the presence of antigliadin antibodies IgA and IgG, antiendomysium antibodies IgA, as well as antihuman transglutaminase IgA following a gluten rich Mediterranean diet. Type 1 diabetes mellitus was excluded according to the 1997 American Diabetes Association criteria, and none of the participants had a family history of diabetes mellitus. Other intestinal and endocrine diseases were excluded through clinical and, when indicated, laboratory evaluation. Food or other allergies were excluded. None of the subjects reported gastrointestinal signs or symptoms, or was a habitual smoker, abuser of alcohol, or regularly took non-steroidal anti-inflammatory drugs