Functional MR of the primary auditory cortex: an analysis of pure tone activation and tone discrimination.

PURPOSETo use functional MR imaging to measure the effect of frequency (pitch), intensity (loudness), and complexity of auditory stimuli on activation in the primary and secondary auditory cortexes.METHODSMultiplanar echo-planar images were acquired in healthy subjects with normal hearing to whom auditory stimuli were presented intermittently. Functional images were processed from the echo-planar images with conventional postprocessing methods. The stimuli included pure tones with a single frequency and intensity, pure tones with the frequency stepped between 1,000, 2,000, 3,000, or 4,000 Hz, and spoken text. The pixels activated by each task in the transverse temporal gyrus (TTG) and the auditory association areas were tabulated.RESULTSThe pure tone task activated the TTG. The 1,000-Hz tone activated significantly more pixels in the TTG than did the 4,000-Hz tone. The 4,000-Hz tone activated pixels primarily in the medial TTG, whereas the 1,000-Hz tone activated more pixels in the lateral TTG. Higher intensity tones activated significantly more pixels than did lower intensity tones at the same frequency. The stepped tones activated more pixels than the pure tones, but the difference was not significant. The text task produced significantly more activation than did the pure tones in the TTG and in the auditory association areas. The more complex tasks (stepped tones and listening to text) tended to activate more pixels in the left hemisphere than in the right, whereas the simpler tasks activated similar numbers of pixels in each hemisphere.CONCLUSIONAuditory stimuli activate the TTG and the association areas. Activation in the primary auditory cortex depends on frequency, intensity, and complexity of the auditory stimulus. Activation of the auditory association areas requires more complex auditory stimuli, such as the stepped tone task or text reading.     

Gadolinium-enhanced magnetic resonance imaging in temporal bone lesions

A 2-year experience with an enhancement agent in magnetic resonance imaging (MRI) is examined through case presentations. Characteristics of the agent Gadolinium DTPA/Dimeglumin are reviewed. Radiographic capabilities in enhanced versus unenhanced MRI are compared. Temporal bone lesions, including acoustic neuromas and facial nerve neuromas, are presented. Recent experience with facial nerve enhancement in Bell's palsy is also presented. Greater accuracy in defining small temporal bone lesions and increased delineation of facial nerve involvement appear to be significant benefits with enhanced MRI.     

The prevalence of airways hyperresponsiveness in members of an exercise training facility.

Athletes have a high prevalence (11-50%) of exercise-induced asthma, which may be caused by the hyperventilation accompanying repetitive bouts of strenuous exercise. We hypothesized that recreational exercisers would display a similar trend. Eucapnic voluntary hyperventilation (EVH) bronchoprovocation (breathing 21% O2, 5% CO2, and 74% N2 at 60% of MVV for 5 minutes) was performed to determine the prevalence of airways hyperresponsiveness (AHR) in adults (n=212, 146 males, mean +/- standard deviation, age 32 +/- 10 years) who exercised regularly (10 +/- 10 years, 31 +/- 28% of their lives): none had a previous diagnosis of asthma. AHR was defined by at least a 10%, 20%, or 25% decline in FEV1, FEF(25-75), or PEFR, respectively, by spirometry at 1, 5, 10, and 15 minutes post-EVH. Forty-one of 212 (19%) tested positive for AHR: 20 of 41 (49%) were positive by FEV1, 28 of 41 (68%) by FEF(25-75), and 27 of 41 (66%) by PEFR. Comparing responders with nonresponders: pre-EVH lung function was equivalent, except for FEV1, which was reduced (p<0.05) in responders (96 +/- 13 vs. 102 +/- 12% predicted). Mean maximal negative deflections for responders were: for FEV1, -17 +/- 7%; FEF(25-75), -31 +/- 10%; PEFR, -38 +/- 11%. Ranges of decline for responders were: FEV1, -10 to -33%; FEF(25-75), -20 to -59%; PEFR, -25- to -70%. We conclude that in these regular exercisers, the prevalence of AHR is high and comparable with some athletic populations.     

Antibody-mediated neutralization of pertussis toxin-induced mitogenicity of human peripheral blood mononuclear cells

Antibody-mediated neutralization of pertussis toxin-induced proliferation of human peripheral blood mononuclear cells (PBMC) was assessed using alamarBlue and compared with results from the Chinese hamster ovary (CHO) cell assay using sera from vaccinated adults and convalescent children. Neutralization values for the CHO assay were similar for vaccinated and convalescent subjects; however. the convalescent group had higher titers in the PBMC assay. Results for pertussis toxin neutralization with the CHO assay appear to be distinct from those with the PBMC assay.     

Development and malformations of the cerebellum in mice

The cerebellum is the primary motor coordination center of the CNS and is also involved in cognitive processing and sensory discrimination. Multiple cerebellar malformations have been described in humans, however, their developmental and genetic etiologies currently remain largely unknown. In contrast, there is extensive literature describing cerebellar malformations in the mouse. During the past decade, analysis of both spontaneous and gene-targeted neurological mutant mice has provided significant insight into the molecular and cellular mechanisms that regulate cerebellar development. Cerebellar development occurs in several distinct but interconnected steps. These include the establishment of the cerebellar territory along anterior-posterior and dorsal-ventral axes of the embryo, initial specification of the cerebellar cell types, their subsequent proliferation, differentiation and migration, and, finally, the interconnection of the cerebellar circuitry. Our understanding of the basis of these developmental processes is certain to provide insight into the nature of human cerebellar malformations.     

Clinical characteristics and outcomes associated with Inquilinus infection in cystic fibrosis

BackgroundMolecular diagnostics have led to the identification of a broad range of bacterial species in cystic fibrosis (CF) including Inquilinus. The clinical significance of Inquilinus in CF has not been thoroughly characterized.MethodsRetrospective, case-control study of persons with CF from two CF centers with at least one respiratory culture positive for Inquilinus spp. compared with age-matched CF controls with chronic Pseudomonas aeruginosa. Percent predicted forced expiratory volume in one second (ppFEV1) and body mass index percentile (BMI) were modeled from time of first positive culture up to 5 years later. Rates of pulmonary exacerbations were compared. Inquilinus isolates were genotyped to evaluate strain diversity.ResultsSeventeen patients with Inquilinus infection were identified with a mean age of 13 years at first positive culture. Most cases had multiple cultures positive for Inquilinus. ppFEV1 was not different between cases versus controls (80.2% vs 81.6%, p = 0.97 at baseline, 67.5% vs. 73.3%, p = 0.82 at 5 years). Patients were undernourished and BMI percentiles did not differ between groups (30.7% vs 43.4%, p = 0.32 at baseline, 37.9% vs. 37.6%, p = 0.98 at 5 years). There was no difference in the pulmonary exacerbation rate (3.0/year vs 2.5/year, p = 0.34). Genotyping showed diverse genetic strains between patients.ConclusionsInquilinus can present in childhood and is often associated with chronic infection in CF. Lung function and nutrition status at time of detection, lung function decline, and pulmonary exacerbation rates in Inquilinus cases were similar to those with chronic P. aeruginosa, a well-established CF pathogen.     

Disease severity impacts the relationship of apelin with arterial function in patients with rheumatoid arthritis

Apelin can improve arterial function by enhancing the expression of endothelial nitric oxide synthase but this effect depends markedly on endothelial integrity. We hypothesized that inflammation influences the potential impact of apelin on arterial function in rheumatoid arthritis (RA). We assessed the associations of apelin concentrations with arterial stiffness (pulse wave velocity), wave reflection (augmentation index, reflected wave pressure, and reflection magnitude), and pressure pulsatility (central systolic pressure (CSP), central pulse pressure (CPP), peripheral pulse pressure (PPP), pulse pressure amplification (PPamp), and forward wave pressure (Pf)) among 170 RA patients without cardiovascular disease. In multivariable regression models, apelin concentrations were not independently associated with arterial function measures (p?≥?0.15) in all patients. Inflammation markers were not consistently associated with apelin levels but joint deformity counts, Disease Activity Score in 28 joints (DAS28), and erythrocyte sedimentation rate (ESR) impacted apelin-pressure pulsatility relations (interaction p?≤?0.05). In stratified analysis, apelin was associated with CSP (partial r?=???0.33, p?=?0.01), CPP (partial r?=???0.26, p?=?0.04), PPamp (partial r?=?0.27, p?=?0.03), and Pf (partial r?=???0.33, p?=?0.01) in patients without but not with joint deformities; apelin was related to CSP (partial r?=???0.24, p?=?0.05) in those with a DAS28 joint <?2.8 (median value) (partial r?=???0.24, p?=?0.05) but not ≥?2.8, and to CSP (partial r?=???0.36, p?=?0.003) in those with an erythrocyte sedimentation rate <?13 mm/h (median value) but not ≥?13 mm/h. Apelin is associated with reduced pressure pulsatility in RA patients without but not with a high inflammatory burden. A loss of apelin protective effects on arterial function may contribute to the link between RA severity and cardiovascular risk.