Instrumental and test-retest reliability of saccadic measures

Little is known about the reliabilities of the various measures of saccade control that can be derived from pro- and anti-saccade tasks. This paper presents correlational results of 2 different studies comprising altogether 446 psychiatrically and neurologically healthy participants in the range of 6-88 years. Saccades were elicited under different stimulation conditions and during task blocks of 100 or 200 trials. Odd-even and split-half correlations determined for study 1 (N = 327, age 9-88 years) were found to be good to excellent (.60 < or = r < or = .97) for most measures and generalisable over the entire life-span. The 19-month test-retest correlations obtained in study 2 (N = 117, age 6-18 years) ranged between .43 and .66 after controlling for age, and suggest moderate stability of individual differences over time during childhood and adolescence. Hence, these parameters are very useful for concurrent validity studies at every age, but less so for predictive validity studies with children and adolescents.     

Cortical correlates of false expectations during pain intensity judgments--a possible manifestation of placebo/nocebo cognitions

We investigated the effects of expectation on intensity ratings and somatosensory evoked magnetic fields and electrical potentials following painful infrared laser stimuli in six healthy subjects. The stimulus series contained trials preceded by different auditory cues which either contained valid, invalid or no information about the upcoming laser intensity. High and low intensities occurred equally probable across cue types. High intensity stimuli induced greater pain than low intensity across all cue types. Furthermore, laser intensity significantly interacted with cue validity: high intensity stimuli were perceived less painful and low intensity stimuli more painful following invalid compared to valid cues. The amplitude of the evoked magnetic field localized within the contralateral secondary somatosensory cortex (SII) at about 165 ms after laser stimuli varied also both with stimulus intensity and cue validity. The evoked electric potential peaked at about 300 ms after laser stimuli and yielded a single dipole source within a region encompassing the caudal anterior cingulate cortex and posterior cingulate cortex. Its amplitude also varied with stimulus intensity, but failed to show any cue validity effects. This result suggests a priming of early cortical nociceptive sensitivity by cues signaling pain severity. A possible contribution of the SII cortex to the manifestation of nocebo/placebo cognitions is discussed.     

Head lice: scientific assessment of the nit sheath with clinical ramifications and therapeutic options

Head lice, like many insects, produce a protective coating for their newly laid eggs that is essential to the survival of the species. Knowledge of the composition of the sheath, which is the glue by which the egg is attached to human hair, and the nit laying process could lead to production of agents that could be used to attack louse infestations by interfering with the normally protected environment of nymph development within the egg. The physical removal of nits has become an important part of treatment of head louse infestations given the "no-nit" policy in schools. Biochemical analysis has revealed that the nit sheath of the head louse is composed of 4 bands of protein, possibly cross-linked to aliphatic components with a tertiary structure of beta sheeting. Nature has protected the louse by making the nit sheath similar in composition to the hair; thereby, agents designed to unravel the nit sheath may also damage human hair. Possible targets to destroy the nit sheath include proteases, denaturants, beta sheet breaker proteins, and small protein inhibitors of sheath formation. Better understanding of insect glues may allow us to develop compounds so that the liquid secretions of the collateral glands of the female louse, which becomes the nit sheath, do not solidify by oxidation when placed with the louse egg onto human hair. Knowledge of insect behavior, such as oviposition, may also suggest methods for repelling female lice from laying eggs onto hair. Alternatively, agents that coat the nits and restrict the oxygen transfer to the developing larvae may prove beneficial.     

Repeat microvascular decompression for hemifacial spasm

OBJECTIVE: To report our experience with repeat microvascular decompression (MVD) for hemifacial spasm (HFS) in patients who have failed their first operation. METHODS: The authors describe 41 redo MVDs for HFS in 36 patients performed over a 3 year period. Seven patients underwent early re-operation after an aborted seventh nerve decompression. Eight patients underwent early re-operation for clinical failure. Eighteen patients underwent late re-operation for spasm recurrence long after their original MVD. Eight MVDs were performed on patients who had already undergone at least two prior operations. RESULTS: Twenty four patients experienced complete spasm resolution (70.6%), eight patients had near total resolution (23.5%), and two patients failed re-operation (5.9%). Two patients were lost to follow up (5.6%). A favourable outcome was reported by 82.4% of patients at a mean follow up interval of 18 months. A total of 91.7% of patients 50 years of age or younger were cured at follow up versus 59.1% of patients older than 50 (p = 0.04). Patients undergoing early re-operation were significantly more likely to be cured or improved than patients undergoing late re-operation (p = 0.03). CONCLUSIONS: Repeat MVD for HFS is effective in experienced hands. Younger patients respond better to repeat MVD. Late repeat MVD for HFS is a reasonable treatment option, although results are less favourable than for early re-operation.     

Atrioventricular septal defects: effect of bridging leaflet division on early valve function

BACKGROUND: Bridging leaflet division may facilitate repair of atrioventricular septal defects (AVSD). However, the consequences of bridging leaflet division on early valve function and mortality are not well defined. METHODS: Records of children undergoing AVSD repair between January 1995 and January 2002 were reviewed. Multivariable analysis defined risk factors for moderate or greater atrioventricular valve regurgitation (AVVR) and death/reoperation within 1 year of repair. RESULTS: A total of 209 children (median age 5 months, median weight 5 kg) had defects whose repair included the possibility of bridging leaflet division. Bridging leaflets divided were both (n = 119, 58%), one (n = 30, 15%), or none (n = 55, 27%). Freedom from AVVR (moderate or greater) is 84%, 80%, and 78% at 1, 6, and 12 months. Risk factors include technical factors: number of bridging leaflets divided, longer cross-clamp time, and right-sided annuloplasty. Other risk factors include preoperative AVVR (moderate or greater), double-orifice or parachute left AV valve, and younger age. Freedom from death/reoperation for AVVR is 96%, 92%, and 90% at 1, 6, and 12 months. Risk factors are preoperative AVVR (moderate or greater) and parachute left AV valve. Findings at reoperation (n = 15, 7.2%) were cleft dehiscence or tear along cleft closure (n = 10), dehiscence of divided leaflet from septation patch (n = 1), or other (n = 4). Operative mortality (n = 6, 2.9%) included failed reoperations for AVVR (n = 4), dehiscence of divided leaflet from septation patch (n = 1), and sepsis (n = 1). CONCLUSIONS: Division of bridging leaflets is a risk factor for AVVR (moderate or greater) during the first year after repair. Preservation of bridging leaflet integrity may improve valve competency, decrease the need for future reoperation, and eliminate some causes of operative mortality.     

Drug interaction with T-cell receptors: T-cell receptor density determines degree of cross-reactivity

BACKGROUND: Immune-mediated adverse reactions to drugs are often due to T-cell reactivity, and cross-reactivity is an important problem in pharmacotherapy. OBJECTIVE: We investigated whether chemical inert drugs can stimulate T cells through their T-cell receptor (TCR) and analyzed the cross-reactivities to related compounds. METHODS: We transfected human TCRs isolated from two drug-reactive T-cell clones (TCCs) by PCR into a TCR-negative mouse T-cell hybridoma. The TCCs were isolated from a patient with drug hypersensitivity to the antibacterial sulfonamide sulfamethoxazole (SMX). RESULTS: The transfectants reacted to SMX only in the presence of antigen-presenting cells (APCs). Glutaraldehyde-fixed APCs, however, were sufficient to elicit T-cell stimulation, indicating a processing-independent direct interaction of the drug with the TCR and MHC molecule. The transfected hybridomas secreted IL-2 in a drug dose-dependent manner, whereas the degree of reactivity was dependent on the level of TCR expression. One transfectant reacted not only to SMX but also to related sulfonamide compounds. Interestingly, high TCR expression increased cross-reactivity to other structurally related compounds. In addition, SMX-specific TCR cross-reacted only with sulfonamides bearing a sulfanilamide core structure but not with sulfonamides such as celecoxib, furosemide, or glibenclamide. CONCLUSIONS: These results demonstrate that the T-cell reactivity to drugs is solely determined by the TCR. Moreover, these results show that cross-reactivity of structurally similar compounds correlates with the density of the TCR. Stably transfected T-cell hybridomas may represent a powerful screening tool for cross-reactivity of newly generated sulfonamide-containing compounds such as celecoxib.