Inhibitory motor control in children with attention-deficit/hyperactivity disorder: event-related potentials in the stop-signal paradigm.

BACKGROUND: The aim of the study was to investigate the inhibitory control of an ongoing motor response and to identify underlying neural deficiencies, manifested in event-related potentials, that cause poorer inhibitory performance in children with attention-deficit/hyperactivity disorder. METHODS: A stop-signal paradigm with a primary visual task and auditory stop signal was used to compare performance in 13 children with attention-deficit/hyperactivity disorder and 13 control children, while event-related potentials were recorded simultaneously. RESULTS: Children with attention-deficit/hyperactivity disorder showed poorer inhibitory performance through a slower inhibitory process. Inhibitory processing of auditory stop signals was marked by a frontal N2 component that was reduced in the attention-deficit/hyperactivity disorder group relative to controls. A central positive component (P3) was associated with the success of inhibiting a response, but there were no group differences in its amplitude or latency. CONCLUSIONS: Findings support the hypothesis of deficient inhibitory control in children with attention-deficit/hyperactivity disorder. Slower inhibitory processing appears to be due to a specific neural deficiency that manifests in the processing of the stop signal as attenuated negativity in the N2 latency range.     

Effectiveness of a meditation-based stress reduction program in the treatment of anxiety disorders.

OBJECTIVE: This study was designed to determine the effectiveness of a group stress reduction program based on mindfulness meditation for patients with anxiety disorders. METHOD: The 22 study participants were screened with a structured clinical interview and found to meet the DSM-III-R criteria for generalized anxiety disorder or panic disorder with or without agoraphobia. Assessments, including self-ratings and therapists' ratings, were obtained weekly before and during the meditation-based stress reduction and relaxation program and monthly during the 3-month follow-up period. RESULTS: Repeated measures analyses of variance documented significant reductions in anxiety and depression scores after treatment for 20 of the subjects--changes that were maintained at follow-up. The number of subjects experiencing panic symptoms was also substantially reduced. A comparison of the study subjects with a group of nonstudy participants in the program who met the initial screening criteria for entry into the study showed that both groups achieved similar reductions in anxiety scores on the SCL-90-R and on the Medical Symptom Checklist, suggesting generalizability of the study findings. CONCLUSIONS: A group mindfulness meditation training program can effectively reduce symptoms of anxiety and panic and can help maintain these reductions in patients with generalized anxiety disorder, panic disorder, or panic disorder with agoraphobia.     

Syst-Eur--a multicenter trial on the treatment of isolated systolic hypertension in the elderly: first interim report.

Syst-Eur is a multicenter placebo-controlled outcome trial designed by the European Working Party on High Blood Pressure in the Elderly to investigate the effect of antihypertensive treatment on the incidence of stroke in elderly patients with isolated systolic hypertension (ISH). Eligible patients must be at least 60 years old and have a systolic blood pressure averaging 160-219 mm Hg with a diastolic blood pressure less than 95 mm Hg. The present paper is an interim report on the first 316 patients randomized into this trial. The placebo (n = 170) and active treatment (n = 146) groups were similar at randomization with respect to age (73 +/- 8 years; mean +/- SD), sitting blood pressure (178 +/- 12 mm Hg systolic; 85 +/- 7 mm Hg diastolic), percentage of men (34%), and percentage of patients with cardiovascular complications (29%). After randomization blood pressure fell more (p less than 0.001) in patients on active treatment than in those in the placebo group (19 +/- 20 mm Hg systolic; 6 +/- 10 mm Hg diastolic vs. 7 +/- 19 and 1 +/- 10 mm Hg for sitting blood pressure). This first interim report on the Syst-Eur trial demonstrates that a multinational trial in elderly patients with ISH is feasible and that a significant blood pressure difference between the two treatment groups can be achieved and maintained. New centers are being recruited in order to randomize a total of 3,000 patients.     

The orthopan tomoscintigram — a new application of emission computed tomography for facial bone scanning

The exact regional correlation of findings of facial bone scans, planar or SPECT, to dental orthopan X-ray films (OPT) is difficult because of the very different projection techniques. To improve correlative imaging in this regard a projection algorithm was developed that uses SPECT data of the skull for reconstructing an orthopan tomoscintigraphic projection. Fourteen conventional SPECT slices of the upper and lower jaws were obtained during bone scanning. All mandibular slices were superimposed resulting in a horseshoe shaped structure, which was marked by an ROI which was divided into segments. All 14 SPECT slices were then masked by this segmental ROI, thereby marking the teeth-carrying bone in all slices. The information from this horseshoe like ROI is then transformed into lines. Line by line arrangement results in an orthopan projection, the orthopan tomoscintigram. This new display allows 1:1 true scale superimposition with the X-ray OPT and markedly facilitates correlative imaging.     

The importance of calcium ions forin vitro malignant hyperthermia testing

Intracellular Ca++ levels in skeletal muscle are elevated during the in vitro contracture response of muscle from subjects with malignant hyperthermia. The role of Ca++ in the bathing medium and the consequences of substitution of Sr++ for Ca++ in the response to agents associated with malignant hyperthermia were examined. When Ca++ was omitted from the bathing medium the contractures induced in human vastus lateralis by halothane (three per cent) or succinylcholine (50 mM) were reduced by 80 and 100 per cent, respectively, while contractures induced by caffeine (8 mM) were only reduced by 50 per cent. Substitution of Ca++ by another divalent cation, Sr++, completely restored contractures induced by caffeine, but only partially restored contractures induced by halothane or succinylcholine (to 50 and 30 per cent of Ca(++)-containing medium, respectively). Mepacrine (10 microM) was effective in antagonizing contractures by caffeine, whereas verapamil and nifedipine (10 microM) were not. These results support an essential role for extracellular Ca++ not fulfilled by Sr++ in contracture induction by halothane and succinylcholine, but not by caffeine.     

Magnetic Forces on Orthodontic Wires in High Field Magnetic Resonance Imaging (MRI) at 3 Tesla

BACKGROUND: In a previous investigation we reported on magnetic forces in the static magnetic field of a 1.5 Tesla MRI system. The aim of the present investigation was to assess forces on orthodontic wires in a high field strength MRI system at 3 Tesla. MATERIALS AND METHODS: Thirty-two different orthodontic wires (21 archwires, eight ligature wires and three retainer wires) were investigated in a 3 Tesla high field strength MRI system (Intera, Philips Medical Systems, Best, The Netherlands). Translational forces were measured by the deflection angle test (ASTM F2052-02), and rotational forces assessed on a 5-point qualitative scale. RESULTS AND CONCLUSION: Translational forces ranged between 43.5 mN and 136.1 mN for retainer wires and between 0.6 mN (Noninium) and 208.4 mN (Orthos Stainless Steel) for steel archwires. Translational forces were up to 53.8 times as high as gravitational forces for retainer wires and up to 54.5 times as high for steel archwires, associated with marked rotational forces for the most part. Archwires manufactured from nickel-titanium, titanium-molybdenum and cobalt-chromium and different ligature wires showed no or negligible forces in the magnetic field. Carefully ligated wires should not present a risk due to translational and rotational forces in the high field MRI system at 3 Tesla.     

Clinical medicine meets modern epidemiology--and both profit.

The clinical epidemiology movement can be understood best through the work of people who have chosen to call themselves clinical epidemiologists. It has strong ties to both clinical medicine and epidemiology but is distinct from them; it bridges the two disciplines and helps each recognize and use the strengths of the other. Epidemiology has given clinicians strong methods for answering clinical questions, a population perspective on the care of individual patients, and the scientific basis for preventive health care. Clinicians have brought to epidemiology in-depth understanding of the biology of disease, direct experience with epidemiologic variables, and a strong interest in how the results of research will be used. The success of clinical epidemiology are apparent through research, courses, textbooks, and contributions to clinical and public policy. Clinical medicine and epidemiology began together, then drifted apart. Both have suffered from the schism and both can now profit from becoming reacquainted.     

Age and gender effects in EEG coherence: III. Girls with attention-deficit/hyperactivity disorder.

OBJECTIVE: This study investigated intrahemispheric and interhemispheric EEG coherences as a function of age in girls with different DSM-IV subtypes of Attention-Deficit/Hyperactivity Disorder (AD/HD). It completes a series of 3 studies aimed at clarifying developmental and gender impacts on the coupling between brain regions in this disorder. METHODS: Three groups of 40 children (AD/HD combined type, AD/HD inattentive type, and normal controls) participated. Each group contained 8 females in each of 5, 1-year age bands from 8 to 12 years. EEG was recorded from 21 sites during an eyes-closed resting condition. Wave-shape coherence was calculated for 8 intrahemispheric electrode pairs (4 in each hemisphere), and 8 interhemispheric electrode pairs, within each of the delta, theta, alpha and beta bands. RESULTS: Developmental effects in intrahemispheric coherences at shorter and longer inter-electrode distances were not as predicted by Thatcher's two-compartment model, contrary to previous findings in boys. Females with AD/HD showed evidence of developmental delay and widespread anomalous elevations in coherence. Girls with AD/HD of the combined type showed similar but greater anomalies than girls with AD/HD of the inattentive type. CONCLUSIONS: Girls with AD/HD show coherence anomalies relative to age- and gender-matched controls, which differ substantially from those shown by boys with AD/HD. These coherence anomalies did not differ in nature between girls with different DSM-IV subtypes of AD/HD, suggesting that subtype differences in girls reflect only symptom severity. SIGNIFICANCE: The data reported here indicate qualitative differences in EEG coherences in girls with AD/HD compared with controls, and quantitative differences between girls with different subtypes of AD/HD. Both sets of effects differ in nature from those previously found in boys with AD/HD, showing the need to carefully consider gender in future studies of AD/HD.