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Biomedical subjects

B Ross

Publications and source records attributed to B Ross.

227 records · Page 13Linked to original sources
PubMedDate not supplied

Frequency-specific threshold determination with the CERAgram method: basic principle and retrospective evaluation of data.

A method for the objective evaluation of the hearing threshold using cortical evoked response audiometry was developed. The method results in a kind of objective audiogram, visualizing the significance of an auditory evoked potential (AEP) in a scheme similar to a conventional audiogram. In the present implementation of the method, four frequencies are tested quasi-simultaneously (500, 1000, 2000 and 3000 Hz; intensity steps of 5 dB). The significance of an evoked potential is assessed by means of the Rayleigh test, which is applied to the phase values derived from certain time windows of the single-trial epochs. A retrospective analysis of 1, 920 threshold estimations in 240 subjects suggested that the detection threshold (lowest stimulus intensity yielding a significant response) was, on the average, 7.5 dB above the electrophysiological threshold (intensity where the AEP amplitude vanishes). The grand-average amplitude-intensity characteristic was approximated by the function a(1 - exp(-I/b)), with a = 6.25 microV, b = 22.3 dB and I representing the intensity (in decibels) relative to the electrophysiological threshold.

Auditory Perception↗
PubMedDate not supplied

Neurophysiological correlate of the auditory after-image ('Zwicker tone').

The 'Zwicker tone' (ZT) is an auditory after-image that can be evoked most effectively when a band-suppressed noise (relative width of gap 1/3 octave) presented for a certain period of time has been switched off. The sensation of this purely monaural phenomenon is that of a pure tone with a frequency corresponding to the center frequency of the gap and an equivalent level of 10-15 dB above auditory threshold. The sensation decays gradually; it may last as long as 10 s depending on how long the evoking noise was presented. The search for a physiological correlate has been futile so far, probably because the search was confined to more peripheral levels of the auditory system (inferior colliculus). A neuromagnetic study was performed in normal-hearing subjects in order to look for a neurophysiological correlate of the ZT in the auditory cortex. With a stimulation paradigm especially designed for this study, we have been able to isolate poststimulus activity which appears to be related to the ZT and which originates in the supratemporal auditory cortex. It is a sustained neuromagnetic activity that shows a clear-cut dipolar field distribution, and it appears that this activity has certain similarities with the tone-evoked auditory sustained response. The hypothesis is put forward that during the sensation of the ZT a process takes place in the auditory cortex which is similar to that underlying the sustained response, and which gives rise to the sensation of the ZT. In contrast to the sustained response, however, which is due to neural activity evoked by an external acoustic stimulus, the sustained activity associated with the ZT is due to a temporary absolute or relative reduction of neural activity originating from those regions in which the ZT exciting stimulus caused an adaptation. These differences in neural activity cannot be distinguished by the auditory system from a corresponding external acoustic signal. Preliminary studies in patients suffering from tonal tinnitus yielded results which exhibit a certain similarity with those obtained in the ZT experiment.

Acoustic Stimulation↗
PubMedDate not supplied

Semiautomated monolayer preparation of bronchial secretions using AutoCyte PREP.

OBJECTIVE: Development of a method for semiautomated preparation of purified, representative and conventionally stained monolayer smears from bronchial secretions suitable for subjective and/or automated cytodiagnosis. STUDY DESIGN: Bronchial secretions from 50 patients with and 48 without carcinoma cells of different types were collected in Saccomanno's fixative. After routine pick-and-smear processing, residual material was subjected to a mucolytic agent (ammonium thioglycolate). Separation of cells was performed by differential centrifugation through aqueous sucrose. The pellet was automatically processed by the AutoCyte PREP system. RESULTS: Slides revealed well-preserved, slightly shrunken, homogeneously distributed cells devoid of mucus, cellular debris and bacteria in monolayer arrangement nearly without overlap. Granulocytes were eliminated to a large extent. Comparison with pick-and-smear specimens showed more tumor cells per square centimeter of slide surface in 100% of AutoCyte PREP slides. The number of tumor cells per AutoCyte PREP slide was higher in 46% and lower in 54%. Selecting slides at random and requiring at least 10 abnormal cells to establish a tumor diagnosis were achieved in 82.7% if only one, in 88.0% if two and 94.0% if seven or eight AutoCyte PREP slides were investigated. CONCLUSION: The semiautomated method yielded conventionally stained, purified monolayer smears from bronchial secretions with cellular morphology suitable for evaluation by cytologists and screening machines. Representativity of AutoCyte PREP monolayers was superior to that of pick-and-smear slides.

Adenocarcinoma↗
PubMedDate not supplied

Renal enlargement as primary presentation of acute lymphoblastic leukaemia.

Renal enlargement in acute lymphoblastic leukaemia is well reported in literature from Western Countries. However there are very few reports from developing countries. Bilateral symmetrical enlargement of kidneys as a primary presentation of acute lymphoblastic leukaemia is rare. We report a child who had acute lymphoblastic leukaemia presenting with bilateral renal mass.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

A comparison of pulmonary artery, rectal, and tympanic membrane temperature measurement in the ICU.

OBJECTIVE: To compare tympanic membrane temperature with pulmonary artery (PA) and rectal temperature (calibrated glass mercury) to determine consistency among measures. DESIGN: Convenience, within-subject, quasi-experimental. SETTING: Midwestern university-affiliated tertiary medical center. PATIENTS: 128 adult (18 years or older) patients admitted to the surgical intensive care unit with an age range of 18 to 90 years (mean 57 years). OUTCOME MEASURES: Tympanic, PA, and rectal temperature. INTERVENTION: Rectal and tympanic membrane temperatures were measured in 60 patients. PA and tympanic membrane temperatures were measured in 68 patients. RESULTS: Rectal and tympanic membrane temperatures were moderately correlated (r = 0.525). Mean rectal was slightly higher than mean tympanic membrane temperature (mean difference 0.19 degrees C). PA and tympanic membrane temperatures were highly correlated (r = 0.909). Mean tympanic membrane temperature was slightly higher than mean PA temperature (mean difference 0.42 degrees C). For PA temperatures, 57 (84%) of the differences were between 0 and +1 degree Celsius, whereas for rectal temperature, 23 (37%) were between 0 and +1 degree Celsius and 28 (47%) were between 0 and -1 degree Celsius. CONCLUSIONS: Tympanic temperature measurements would be an appropriate substitute for PA temperature if the PA catheter has been removed or the PA thermistor is nonfunctional. In addition, this study suggests that to effectively track temperature in a particular patient, the site for temperature measurement must be consistent.

Body Temperature↗
PubMedDate not supplied

An evaluation of a nurse extern program.

Externships are meant to bridge the gap between the educational and practice setting for nursing. This project began with discussions of outcomes for nurse extern programs. The Schutzenhofer Nurse Activity Scale and the Meleis Nurse Self-Description Form were used to measure identified outcomes of professional activities and autonomy. Forty-one participants began the study, but 33 completed the pretest and posttest both. Analysis of data showed a positive correlation in Posttest 1 between age and the Meleis Nurse Self-Description Form (NSDF). Dimensions of professional activity changed most in older students. At the end of Phase 2, analysis of data showed significantly greater professional autonomy. However, no significant change in NSDF was seen throughout time. Participants reported increased self confidence.

Adult↗