The role of low-spatial frequencies in lexical decision and masked priming.

Spatial frequency filtering was used to test the hypotheses that low-spatial frequency information in printed text can: (1) lead to a rapid lexical decision or (2) facilitate word recognition. Adult proficient readers made lexical decisions in unprimed and masked repetition priming experiments with unfiltered, low-pass, high-pass and notch filtered letter strings. In the unprimed experiments, a filtered target was presented for 105 or 400 ms followed by a pattern mask. Sensitivity (d') was lowest for the low-pass filtered targets at both durations with a bias towards a 'non-word' response. Sensitivity was higher in the high-pass and notch filter conditions. In the priming experiments, a forward mask was followed by a filtered prime then an unfiltered target. Primed words, but not non-words, were identified faster than unprimed words in both the low-pass and high-pass filtered conditions. These results do not support a unique role for low-spatial frequency information in either facilitating or making rapid lexical decisions.

The maturation of form and motion perception in school age children.

The purpose of the current study was to investigate the maturation of form and motion perception, specifically the component visual abilities involved in the identification of motion-defined form, in children ranging in age from 3 to 12 years. Experiment 1 compared the maturation of motion-defined and texture-defined shape identification. Minimum speed thresholds on the motion-defined shape task decreased until age 7 years. Orientation difference thresholds on the texture-defined shape task decreased until age 11 years. Experiment 2 compared the maturation of global motion and global texture direction discrimination. Coherence thresholds on both tasks were similar in children of all ages and adults. Experiment 3 compared the maturation of direction discrimination on motion coherence and motion displacement tasks. Maximum displacement thresholds (Dmax) increased until age 7 years. The results are discussed with respect to the maturation of M/dorsal and P/ventral visual pathways.

A whole head MEG study of the amplitude-modulation-following response: phase coherence, group delay and dipole source analysis.

OBJECTIVE: The amplitude-modulation-following response (AMFR) is the frequency component detectable in the electroencephalogram (EEG) or magnetoencephalography (MEG) corresponding to the modulation frequency of an amplitude modulated tone used as a continuous acoustic stimulus. Various properties of the AMFR depend on modulation frequency, suggesting that different generators along the auditory pathway are involved. The present study addresses these issues on the basis of a whole head MEG experiment. METHODS: AM tones with modulators in the 40 Hz and 80 Hz range were presented unilaterally to 10 normal hearing subjects. Biomagnetic responses were recorded with a 151 channel MEG system. The data analysis concentrated on the phase coherence of the responses, group delays and the estimated location of underlying equivalent dipole sources. RESULTS: MEG AMFR is more reliably detected in the 40 Hz than in the 80 Hz range. Both response amplitude and phase coherence indicate clear bilateral activation over the parietal/temporal region. Dipole source analysis confirms that sources are located in or near the auditory cortex. Group delays at 80 Hz are shorter than at 40 Hz. CONCLUSIONS: In both modulation frequency ranges MEG responses are dominated by activity in the auditory cortex, in apparent contrast with EEG data in the literature, pointing to dominant contributions of thalamic sources to the 80 Hz AMFR.

Expression of interleukin 13 receptor in glioma and renal cell carcinoma: IL13Ralpha2 as a decoy receptor for IL13.

Glioma and renal cell carcinoma (RCC) cells express high affinity interleukin 13 (IL13) binding sites, but only RCC cell proliferation was inhibited by IL13. Both of these two cell types are IL2-receptor (gamma)c chain-negative. We thus used these cell models to investigate the patterns of expression of IL13Ralpha1, IL13Ralpha2, and IL4Ralpha chains and the role of IL13Ralpha2 in the response to IL13. Using new specific antibodies and flow cytometry, we observed a similar surface expression of IL4Ralpha and IL13Ralpha1 chains in most RCC and glioma cells, whereas IL13Ralpha2 was only present on five of six glioma cell lines. In all glioma cell lines, the amount of IL13Ralpha2 expression was 10 to 30 times higher than that of the two other chains. Although there was no surface or intracellular expression of IL13Ralpha2, its mRNA was detected in three of seven RCC cell lines. The expression on RCC cells of IL13Ralpha2 mRNA and/or that of high-affinity IL13 binding sites is not sufficient to predict IL13Ralpha2 protein expression. Blocking experiments showed that IL4 and IL13 strongly inhibited RCC cell proliferation through a unique receptor composed of IL4Ralpha and IL13Ralpha1 chains. Using RCC cells stably transfected with IL13Ralpha2 cDNA, we showed that the overexpression of IL13Ralpha2 decreased the response to IL13 but not that to IL4. Our results demonstrate that IL13Ralpha2 acts as a decoy receptor for IL13 and that it may exert a tight regulation of IL13 activity without impairing the IL4 response of the same cell target.

The Frye hearing in Florida: an attempt to exclude scientific evidence.

State Supreme Courts require a minimum threshold of reliability and acceptance in the scientific community for all medical and similar evidence to be admitted at trial. In Florida and some other states, the courts adhere to what is known as the Frye standard, whereas in most states and in Federal Courts, it is the so-called Daubert standard. The jurisdiction of the present case is Hillsborough County (Tampa), Florida. Forensic pathologists seldom, if ever, are requested to participate in such hearings, unlike their toxicological and basic science colleagues who are more involved in research methodology and technical procedures. The burden is on the proponent of the evidence to prove the general acceptance of both the underlying scientific principle of the test and procedures used to apply that principle to the facts of the case at hand. The trial judge has the sole discretion to determine this question and general acceptance must be established by a preponderance of the evidence. The authors describe in detail a hearing in a case in which they were all involved. One author (WQS) had researched and documented the original scientific methodology in the literature. The situation involved a car and tractor trailer crash with the two occupants of the car dying of multiple trauma, whereas the truck driver was not injured. Autopsy of the auto driver revealed multiple injuries with exsanguination, and only vitreous humor and liver tissue, but not blood, were tested for ethyl alcohol. The estate of the driver of the automobile brought suit against the owner of the trucking company for wrongful death. The plaintiff requested a Frye hearing to question the reliability of testing other body specimens to translate to probable blood alcohol level. The testimony, submitted documents, and eventual decision by the judge are discussed.

Ab initio calculations on peptide-derived oxazoles and thiazoles: improved molecular mechanics parameters for the AMBER force field.

Ab initio calculations at the RHF/6-31G* and MP2/6-31G*//RHF/6-31G* levels of theory are performed for 2-methyl-4-carboxamido-oxazoles and -thiazoles, including rotational profiles for the ring-carboxamide bond, which showed the expected conjugation and hydrogen bonding effects. On the basis of these data, newly optimised stretch, bend and torsional parameters for the AMBER* force field are derived, along with CHELPG-fitted partial atomic charges.

Visual processing of verbal and nonverbal stimuli in adolescents with reading disabilities.

This study investigated whether a group of children with reading disabilities (RD) were slower at processing visual information in general (compared to a group of children of comparable age and a group of children of comparable reading level), or whether their deficit was specific to the written word. Computerized backward masking and temporal integration tasks were used to assess the speed of visual information processing. Stimulus complexity (simple, complex) and type (verbal, nonverbal) were varied, creating a 2 x 2 matrix of stimulus conditions: simple nonverbal, complex nonverbal, simple verbal, and complex verbal. Adolescents with RD demonstrated difficulties in processing rapidly presented verbal and nonverbal visual stimuli, although the effect was magnified when they were processing verbal stimuli. Thus, the results of this study suggest that some youth with reading disabilities have visual temporal processing deficits that compound difficulties in processing verbal information during reading.

Cardiorespiratory adaptation of COPD patients to physical training on land and in water.

Physical training in water might be included in a comprehensive pulmonary rehabilitation programme, but data on the feasibility and safety of this technique in chronic obstructive pulmonary disease (COPD) patients are lacking. We studied cardiorespiratory parameters of 20 stable COPD patients (10 with forced expiratory volume in one second (FEV1) < 35% of predicted value, and 10 with FEV1 > or = 35% pred) on land and in a temperate-controlled pool (32 degrees C) both at rest and during a 15 min submaximal upper body muscle training programme. Compared to resting values on land, we found in water a decrease of systolic and diastolic blood pressure (14 and 6 mmHg, respectively), rate-pressure product (7%) and lung function (vital capacity (VC) 12%, FEV1 14%, peak expiratory flow (PEF) 18%). There were no differences in heart rate, breathing frequency or O2 saturation. The most strenuous exercise in water resulted in a slightly lower O2 saturation compared to work on land (95 and 93%, respectively), and an increase of Borg rating for dyspnoea from 4 to 5. In spite of the restriction of lung function in water, all patients (even those with FEV1 < 35% pred) performed the training in the pool well, without clinically relevant desaturation, arrhythmia or discomfort. No training session was discontinued due to dyspnoea. We conclude that a 15 min session of submaximal physical training in a pool with a water temperature of 32 degrees C is feasible and safe for nonhypoxaemic normotensive COPD patients without cardiac failure.