Variation in acoustic overstimulation changes tinnitus characteristics.

Tinnitus often occurs after exposure to loud noise. This raises the question of whether repeated exposure to noise increases the risk of developing tinnitus. We thus studied tinnitus development after repeated acoustic overstimulation using startle and auditory brainstem-response techniques applied to Mongolian gerbils. Noise with bandwidths ranging from 0.25 up to 0.5 oct were used for repeated acoustic overstimulation. Auditory brainstem response measurements revealed similar threshold shifts in both groups of up to about 30 dB directly after the acoustic overstimulation. We identified an upper limit in threshold values, which was independent of the baseline values before the noise exposure. Several weeks after the acoustic overstimulation, animals with the noise bandwidth of 0.25 oct showed a permanent threshold shift, while animals of the group with the 0.5-oct noise band featured only a temporary threshold shift. We thus conclude that the threshold shift directly after noise exposure cannot be used as an indicator for the upcoming threshold level several weeks later. By using behavioral measurements, we investigated the frequency-dependent development of tinnitus-related changes in both groups and one group with 1-oct noise bandwidth. The number of animals that show tinnitus-related changes was highest in animals that received noise with the bandwidth 0.5 oct. This number was, in contrast to the number of animals in the 0.25-oct bandwidth, not significantly increased after repeated overstimulation. The frequency distribution of tinnitus-related changes ranged from 4 to 20 kHz. In the group with the narrow-band noise (0.25 oct) changes center at one frequency range from 10 to 12 kHz. In the group with the broader noise band (0.5 oct), however, two peaks at 8-10 kHz and at 16-18 kHz were found, which suggests that different mechanisms underlie the tinnitus development.

Reactivity of titanium dioxide with oxygen at room temperature and the related charge transfer.

The measurements of electron work function were applied for in situ monitoring of the charge transfer during oxidation and reduction for well-defined titanium dioxide, TiO 2, at room temperature. The TiO 2 specimen was initially standardized at 1173 K in the gas phase of controlled oxygen activity, at p(O 2) = 10 Pa, and then cooled down in the same gas phase. The work function changes were monitored during oxidation at room temperature at p(O 2) = 75 kPa and subsequent reduction at p(O 2) = 10 Pa. It is shown that oxidation of TiO 2 at room temperature results in fast oxygen chemisorption, involving initially the formation of singly ionized molecular oxygen species, followed by the formation of singly ionized atomic oxygen species, and subsequent slow oxygen incorporation. Although all these processes lead to work function increase, the components of the work function changes related to the individual processes may be distinguished based on different kinetics. The obtained work function data indicate that oxidation results in rapid surface coverage with singly ionized molecular oxygen species, which are subsequently dissociated leading to the formation of singly ionized atomic species. The related chemisorption equilibria are established within 2 and 5 h, respectively. Oxygen incorporation leads to slow work function changes, which achieve a maximum within 100 h. The determined work function data were assessed by using a theoretical model that describes the electrical effects related to different mechanisms of TiO 2 oxidation. The work function data indicate that oxygen incorporation leads to structural changes of the outermost surface layer resulting, in consequence, in a change of the external work function component. Reimposition of the initial gas phase, p(O 2) = 10 Pa, leads to partial desorption of weakly adsorbed molecular species formed during oxidation.

Defect disorder of titanium dioxide.

The present work derived defect disorder diagram representing the effect of oxygen activity on the concentration of both ionic and electronic defects for undoped TiO2. This diagram was determined using the equilibrium constants derived in the present work, including (i) the intrinsic electronic equilibrium constant, (ii) the equilibrium constant for the formation of oxygen vacancies, and (iii) equilibrium constant for the formation of titanium vacancies. These equilibrium constants are consistent with three properties determined independently, including: electrical conductivity, thermoelectric power and change of mass determined by thermogravimetry. The derived defect disorder diagram may be used for tailoring semiconducting properties of TiO2 that are desired for specific applications through the selection of optimized processing conditions.

TiO2 surface active sites for water splitting.

The mechanism of photoreactivity between the TiO(2) surface and H(2)O, and the related charge transfer, is considered in terms of both collective and local properties. It is shown that the effective charge transfer between TiO(2) and water requires the presence of surface active sites that are able to provide electron holes to adsorbed water molecules. Titanium vacancies located at or near the surface are identified as the active sites for water adsorption leading to the formation of an active complex and resulting, in consequence, in water splitting. A model of the photoreactivity between the TiO(2) surface and water is proposed. This model indicates that the photoreactivity of the TiO(2)-based photoelectrode may be enhanced through imposition of the surface active sites (Ti vacancies) in a controlled manner by surface engineering.

Electrical properties and defect chemistry of TiO2 single crystal. I. Electrical conductivity.

The present work reports the electrical properties of high-purity single-crystal TiO(2) from measurements of the electrical conductivity in the temperature range 1073-1323 K and in gas phases of controlled oxygen activities in the range 10(-13) to 10(5) Pa. The effect of the oxygen activity on the electrical conductivity indicates that oxygen vacancies are the predominant defects in the studied ranges of temperature and oxygen activities. The electronic and ionic lattice charge compensations were revealed at low and high oxygen activities, respectively. The determined semiconducting quantities include: the activation energy of the electrical conductivity (E(sigma) = 125-205 kJ.mol(-1)), the activation energies of the electrical conductivity components associated with electrons (E(n) = 218 kJ.mol(-1)), electron holes (E(p) = 34 kJ.mol(-1)), and ions (E(i) = 227 kJ.mol(-1)), and the enthalpy of motion for electronic defects (DeltaH(m) = 4 kJ/mol). The electrical conductivity data are considered in terms of the components related to electrons, holes, and ions. The obtained data allow the determination of the n-p demarcation line in terms of temperature and oxygen activities. The band gap determined from the electronic component of the electrical conductivity is 3.1 eV.

Electrical properties and defect chemistry of TiO2 single crystal. II. Thermoelectric power.

The present work reports the thermoelectric power of high-purity single-crystal TiO(2) in the temperature range 1073-1323 K and in gas phases of controlled oxygen activities, p(O(2)), in the range 10(-13) to 7.5 x 10(4) Pa. The thermoelectric power versus log p(O(2)) dependence for strongly reduced TiO(2) at p(O(2)) < 10(-5) Pa may be approximated by a slope of 1/6, which is consistent with the defect disorder governed by electronic charge compensation of oxygen vacancies. The thermoelectric power data confirm that oxygen vacancies are the predominant ionic defects. These data indicate that TiO(2) at high p(O(2)) exhibits p-type properties. It is shown that the p(O(2)) related to the n-p transition increases with increase of temperature.

Electrical properties and defect chemistry of TiO2 single crystal. III. Equilibration kinetics and chemical diffusion.

The equilibration kinetics of high-purity single-crystal TiO(2) were monitored using measurements of electrical conductivity in the temperature range 1073-1323 K and oxygen activity, p(O(2)), range 10(-13) to 75 kPa. The kinetics data were used to determine the chemical diffusion coefficient (D(chem)) within narrow ranges of p(O(2)). There was observed a complex effect of the p(O(2)) on the D(chem), which exhibits a maximum at the n-p transition. The effect of the p(O(2)) on the D(chem) was discussed in terms of the defect disorder and the related semiconducting properties. The activation energy of the D(chem), which also varies with the p(O(2)), exhibits a maximum at p(O(2)) = approximately 10(4) Pa (143 kJ/mol).

Electrical properties and defect chemistry of TiO2 single crystal. IV. Prolonged oxidation kinetics and chemical diffusion.

Measurements of both electrical conductivity and thermoelectric power were used to monitor the equilibration kinetics of undoped single-crystal TiO(2) during prolonged oxidation at 1123 and 1323 K and p(O(2)) = 75 kPa. Two kinetics regimes were revealed: kinetics regime I (rapid kinetics), which is rate-controlled by the transport of oxygen vacancies, and kinetics regime II (slow kinetics), which is rate-controlled by the transport of titanium vacancies. The incorporation of titanium vacancies allows undoped p-type TiO(2) to be processed in a controlled manner. The kinetics data were used to determine the chemical diffusion coefficient (D(chem)) associated with the transport of titanium vacancies, which is equal to D(chem) = 8.9 x 10(-14) m(2) s(-1) and D(chem) = 9.3 x 10(-15) m(2) s(-1) at 1323 and 1123 K, respectively.

Disabling neurological syndromes: prevalence amongst hospitalized neurological patients.

Neurological patient populations are usually described by diagnosis or in terms of functional disability measures but rarely by their clinical syndromes. A point-prevalence study was conducted assessing 349 neurological inpatients to determine the frequency and co-occurrence of disabling neurological syndromes, considering a wider spectrum including pain, emotional, neuropsychological, vegetative and sensorimotor syndromes. Of the study patients, 61% (n = 224) had sensorimotor syndromes, 53% (n = 185) had neuropsychological disorders, 40% (n = 139) of the patients suffered from pain, emotional disorders were found in 36% (n = 122) and vegetative disorders in 33% (n = 113). Although frequency varied by neurological diagnosis, these disabling conditions were found across all inpatient groups of diagnosis. Similarly, disorders outside the motor domains grouped according to their Barthel Index showed a striking frequency in patients considered as activities of daily living independent, reflecting a wider spectrum of disability that functional measures are not able to capture. Of the study population, 68% (n = 237) suffered from co-occurring disorders from different categories (pain, emotional, neuropsychological, vegetative and sensorimotor syndromes). There is a high prevalence and co-occurrence of disabling syndromes in neurological inpatients. These proportions reflect the neurological workload in a patient population and should be considered in future rehabilitation research and allocation of resources.

[Electromechanical transduction: influence of the outer hair cells on the motion of the organ of Corti]. / Elektromechanische Transduktion: Einfluss der äusseren Haarsinneszellen auf das Bewegungsmuster des Corti-Organs.

BACKGROUND: The somatic electromotility of the outer hair cells can be induced by an extracellular electrical field. This enables us to investigate the electromechanically induced motion of the organ of Corti. METHODS: The electrically induced motion of the guinea-pig organ of Corti was measured with a laser Doppler vibrometer in three cochlear turns at ten radial positions on the reticular lamina (RL) and six on each of the upper and lower surfaces of the tectorial membrane (TM). RESULTS AND CONCLUSIONS: We found a complex vibration pattern of the RL and TM, leading to a stimulus synchronous modulation of the depth of the subtectorial space in the region of the inner hair cells (IHCs). This modulation causes radial fluid motion inside the space up to at least 3 kHz. This motion is capable of deflecting the IHC stereocilia and provides an amplification mechanism additional to that associated with basilar-membrane motion.

Near-total absence of the cerebellum.

We report five cases of near-total absence of the cerebellum with accompanying pontine hypoplasia. The cerebellar remnant in each case comprised only antero-superior masses, the posterior fossa being otherwise fluid filled. Three of these patients, two teenagers and an infant, presented a fairly consistent clinical and neuroradiological phenotype, and a few similar cases are recorded in the literature. The cerebellar remnant was irregular and asymmetrical, and no ventral pontine prominence was discernible. In at least the older two, cerebellar motor functions were not greatly compromised, and intellectual handicap was of a mild degree. We propose that these cases represent a distinct entity of "near-total absence of the cerebellum with flat ventral pons, and relatively mild clinical affection". All cases have been sporadic, implying that the risk of recurrence within a family may be low. Quite different clinical pictures, of considerably greater severity, are demonstrated in the remaining two cases. One had pontocerebellar hypoplasia type 2, while the other had a complex cerebellar and cerebral malformation.

Does psychiatric comorbidity increase the length of stay in general hospitals?

Several studies reported that in non-psychiatric hospital departments mentally ill patients have a longer length of hospital stay than mentally well. But their methods are often limited because other predictors of length of stay were excluded from statistical analyses. Using the Clinical Interview Schedule, research psychiatrists interviewed 993 patients of medical, surgical, gynecological, and rehabilitation departments in Austria. Using several multiple regression analyses, the influence of psychiatric comorbidity and other variables on length of stay was analyzed. 32.2% of all patients suffered from psychiatric morbidity. Of all psychiatric cases, 6.2% received more than one psychiatric diagnosis. Presence of psychiatric disorders, age, a diagnosis of neoplasms, number of all somatic diagnoses, and the number of previous non-psychiatric hospital admissions predicted length of stay. Patients with dementia, with substance abuse disorders, and with alcohol- and drug-related psychiatric disorders showed a significantly increased length of stay, while other psychiatric diagnoses did not differ from the mentally well. Even after controlling for confounding variables, dementia and substance related diagnoses increase the length of hospital stay. It is important to investigate interventions for early recognition and treatment of these disorders.

Characterization of the interaction of calcyclin (S100A6) and calcyclin-binding protein.

Calcyclin (S100A6) is an S100 calcium-binding protein whose expression is up-regulated in proliferating and differentiating cells. A novel 30-kDa protein exhibiting calcium-dependent calcyclin-binding (calcyclin-binding protein, CacyBP) had been identified, purified, and cloned previously (Filipek, A., and Kuznicki, J. (1998) J. Neurochem. 70, 1793-1798). Here, we have defined the calcyclin binding region using limited proteolysis and a set of deletion mutants of CacyBP. A fragment encompassing residues 178-229 (CacyBP-(178-229)) was capable of full binding to calcyclin. CacyBP-(178-229) was expressed in Escherichia coli as a glutathione S-transferase fusion protein and purified. The protein fragment cleaved from the glutathione S-transferase fusion protein was shown by CD to contain 5% alpha-helix, 15% beta -sheet, and 81% random coil. Fluorescence spectroscopy was used to determine calcyclin dissociation constants of 0.96 and 1.2 microm for intact CacyBP and CacyBP-(178-229), respectively, indicating that the fragment can be used for characterization of calcyclin-CacyBP interactions. NMR analysis of CacyBP-(178-229) binding-induced changes in the chemical shifts of (15)N-enriched calcyclin revealed that CacyBP binding occurs at a discrete site on calcyclin with micromolar affinity.

Life on a ventilator.

The increase of patients living at home on ventilator support has become a challenge because few nurses have had training in the care of patients. As the number of patients increases, patients and their caregivers need the support of home healthcare nurses for this to be a successful and positive experience. This personal account of life on a ventilator, written by an esteemed nursing educator and practitioner, gives nurses insight into ways they can be most helpful to these patients.

Chromobacterium violaceum in tropical northern Australia.

Chromobacterium violaceum is an unusual cause of infection which may have fatality rates of over 60% when systemic illness occurs. We describe four patients infected with this organism who were successfully treated at Royal Darwin Hospital between 1991 and 1996. In tropical Australia, C. violaceum infection should be considered along with melioidosis in patients who present with a septic illness with skin lesions and/or organ abscesses after exposure to soil in the wet season.

Effects of K+ channel inhibitors on potassium transport in bovine adrenal chromaffin granules.

The Ca(2+)-independent K+ selective channel in the membrane of adrenal gland chromaffin granules has earlier been identified. In the present report we describe new properties of this potassium channel using 86Rb+, a K+ analogue, flux measurements. The studies are performed in membrane vesicles prepared from chromaffin granules. The electrogenic 86Rb+ transport is inhibited by quinacrine, barium, zinc and magnesium. The effects of other potassium channel blockers on 86Rb+ transport into chromaffin granules are also reported.

Interaction of sulfhydryl reagents with K+ transport in adrenal chromaffin granules.

In the present study the functional role of SH groups in the Ca(2+)-independent K(+)-selective channel activity in the membrane of bovine adrenal gland chromaffin granules has been studied. Ionic channel activity has been estimated using 86Rb+, a K+ analogue, flux measurements. The inhibition of chromaffin granules K+ channel by SH modifying agents, such as N-ethylmaleimide, mersalyl and phenylarsenoxide, is described.

A study to determine the difference in clinical judgment abilities between BSN and non-BSN graduates.

The purpose of this retrospective study is to determine the difference in clinical judgment abilities of recent baccalaureate nurses (BSN) seeking employment in a large metropolitan hospital and of nurses without a baccalaureate degree. Using an ex post facto design, the orientation records of 116 newly hired nurses were analyzed to determine the clinical judgment abilities using video vignettes produced by Medcom, Inc. Findings indicated that there was no difference in clinical judgment in newly hired BSN and non-BSN graduates. These findings indicate a need for more research studies to determine how clinical judgment is developed and to evaluate teaching strategies that facilitate clinical judgment.