Perceptual Sensitivity to High-Frequency Interaural Time Differences Created by Rustling Sounds

Interaural time differences (ITDs) can be used to localize sounds in the horizontal plane. ITDs can be extracted from either the fine structure of low-frequency sounds or from the envelopes of high-frequency sounds. Studies of the latter have included stimuli with periodic envelopes like amplitude-modulated tones or transposed stimuli, and high-pass filtered Gaussian noises. Here, four experiments are presented investigating the perceptual relevance of ITD cues in synthetic and recorded “rustling” sounds. Both share the broad long-term power spectrum with Gaussian noise but provide more pronounced envelope fluctuations than Gaussian noise, quantified by an increased waveform fourth moment, W. The current data show that the JNDs in ITD for band-pass rustling sounds tended to improve with increasing W and with increasing bandwidth when the sounds were band limited. In contrast, no influence of W on JND was observed for broadband sounds, apparently because of listeners' sensitivity to ITD in low-frequency fine structure, present in the broadband sounds. Second, it is shown that for high-frequency rustling sounds ITD JNDs can be as low as 30 μs. The third result was that the amount of dominance for ITD extraction of low frequencies decreases systematically with increasing amount of envelope fluctuations. Finally, it is shown that despite the exceptionally good envelope ITD sensitivity evident with high-frequency rustling sounds, minimum audible angles of both synthetic and recorded high-frequency rustling sounds in virtual acoustic space are still best when the angular information is mediated by interaural level differences.     

Detection of Treponema pallidum in the vitreous by PCR

BACKGROUND: Ocular involvement of syphilis still poses a clinical challenge due to the chameleonic behaviour of the disease. As the serodiagnosis has significant limitations, the direct detection of Treponema pallidum (TP) in the vitreous represents a desirable diagnostic tool. METHODS: Real-time polymerase chain reaction (PCR) for the detection of TP was applied in diagnostic vitrectomies of two patients with acute chorioretinitis. Qualitative verification of TP by real-time PCR and melting point analysis according to a modified protocol was ruled out. Patients underwent complete ophthalmological examination with fundus photographs, fluorescein angiography, serological examination, antibiotic treatment and follow-up. RESULTS: In two cases of acute chorioretinitis of unknown origin, real-time PCR of vitreous specimens of both patients provided evidence of TP and was 100% specific. Initial diagnosis of presumed viral retinitis was ruled out by PCR of vitreous specimen. Patients were treated with systemic antibiotics and showed prompt improvement in visual function and resolution of fundus lesions. CONCLUSIONS: With real-time PCR, detection of TP in the vitreous was possible and delivered a sensitive, quick and inexpensive answer to a disease rather difficult to assess. In cases of acute chorioretinitis, the use of PCR-based assays of vitreous specimens in the diagnostic evaluation of patients is advisable. Although syphilitic chorioretinitis is a rare disease, PCR should include search for TP, as diagnostic dilemmas prolong definitive treatment in a sight-threatening disease.     

Assessment of dσ*/dtmax, a Load Independent Index of Contractility, in the Canine

The search for a load-independent index of myocardial contractility has been a focus for nearly 100 years. Nearly all of the parameters developed have yielded insight into cardiac function but their clinical utility has been limited. A new index, dσ*/dt _max, has been proposed to be useful in the clinic. This parameter is expressed as the maximum time rate of change of the pressure normalized circumferential wall stress (σ* = σ _θ /P, where σ _θ is circumferential wall stress and P is pressure) for a thick walled sphere model of the left ventricle (LV). This definition for a contractility index renders dσ*/dt _max dependent only on LV wall volume (V _m) and maximum time rate of change of the ventricular volume, dV/dt _max. The index dσ*/dt _max has been studied in patients with echocardiogram-derived volume, but up until this point its characteristics in canines have remained unknown. Validating this index in the canine will allow for a more intensive and wide-range investigation of the index that is not available with humans. The purpose of this study was to validate dσ*/dt _max as a load-independent measure of contractility in the canine heart with the hope that it was a noninvasive assessment of contractile function. To assess the load independence of dσ*/dt _max, the index was estimated over a range of preloads (end diastolic volume, EDV) during a vena caval occlusion (VCO). The study was conducted in five canines under various pacing modes [right atrial (RA), right ventricular (RV), left ventricular (LV), and biventricular (BV)] at rates of 90 or 100, and 160 bpm. The animals’ ventricular volume measurements were assessed by conductance catheter, calibrated with echocardiography. A 50 Hz filter was applied to the volume signal before differentiation to obtain dV/dt _max. Echocardiography was used to calculate left ventricle mass and V _m. In eight of ten cases, dσ*/dt _max was significantly correlated with decreasing EDV (p < 0.05). There was also a significant correlation between dσ*/dt _max and dP/dt _max. With a strong correlation between the values of dσ*/dt _max, dP/dt _max, and EDV in all five subjects, dσ*/dt _max is not load independent in the canine heart when preload is altered by a VCO. Further evaluation of this index is required to delineate the situations where dσ*/dt _max can be accurately applied.     

Ibuprofen-associated meningitis in a woman with only serologic evidence of a rheumatologic disorder

A case of ibuprofen-associated meningitis is reported in a previously healthy 26-year-old woman. The association was substantiated with a rechallenge. She had no symptoms of rheumatoid factor and a positive antibody to the intranuclear antigen SS-A.     

Induction of a diffuse mesothelioma in chickens by intraperitoneal inoculation of v-src DNA

The presence of peritoneum-based, cytokeratin-positive tumor cells, as detected under conditions of intravenous inoculation of chickens with a v-src-positive DNA fragment, raised the possibility that such DNA may be inductive for diffuse mesothelioma. To investigate this possibility, chickens were inoculated intraperitoneally with v-src DNA, and the resultant peritoneum-based tumor tissue was subjected to histopathological analysis. On the basis of (i) morphology, (ii) immunohistochemistry/histochemistry, and (iii) ultrastructure, we concluded that this tissue represents a diffuse mesothelioma.     

Nichtkardiale Komorbiditäten bei erwachsenen Patienten mit angeborenen Herzfehlern

Zeitschrift für Herz-,Thorax- und Gefäßchirurgie - Durch verbesserte Behandlungsstrategien erreichen immer mehr Patienten mit angeborenen Herzfehlern (AHF) das Erwachsenenalter....