bluuebunny/crossref_metadata_2025 huggingface dataset:
Discrimination and identification of azimuth using spectral shape
Authors: Shub Daniel E. , Carr Suzanne P. , Kong Yunmi , Colburn H. Steven
Published: November 2008

Monaural measurements of minimum audible angle (MAA) (discrimination between two locations) and absolute identification (AI) of azimuthal locations in the frontal horizontal plane are reported. All experiments used roving-level fixed-spectral-shape stimuli processed with nonindividualized head-related transfer functions (HRTFs) to simulate the source locations. Listeners were instructed to maximize percent correct, and correct-answer feedback was provided after every trial. Measurements are reported for normal-hearing subjects, who listened with only one ear, and effectively monaural subjects, who had substantial unilateral hearing impairments (i.e., hearing losses greater than 60dB) and listened with their normal ears. Both populations behaved similarly; the monaural experience of the unilaterally impaired listeners was not beneficial for these monaural localization tasks. Performance in the AI experiments was similar with both 7 and 13 source locations. The average root-mean-squared deviation between the virtual source location and the reported location was 35°, the average slopes of the best fitting line was 0.82, and the average bias was 2°. The best monaural MAAs were less than 5°. The MAAs were consistent with a theoretical analysis of the HRTFs, which suggests that monaural azimuthal discrimination is related to spectral-shape discrimination.
Geometric and Boundary Element Method Simulations of Acoustic Reflections From Rough, Finite, or Nonplanar Surfaces
Authors: Rathsam Jonathan
Published: November 2008

This dissertation seeks to advance the current state of computer-based sound field simulations for room acoustics. Acoustical designers commonly use geometric simulations for quick sound field predictions. A geometric simulation of reflections from rough surfaces is still under refinement. The first project in this dissertation investigates the scattering coefficient, which quantifies the degree of diffuse reflection from rough surfaces. The main result is that predicted reverberation time varies inversely with scattering coefficient if the sound field is nondiffuse. Geometric acoustics is a high-frequency approximation to wave acoustics. Acoustical designers encounter the limits of geometric acoustics when simulating the low-frequency response from finite suspended reflector panels. The second project in this dissertation uses the rigorous boundary element method (BEM) to develop an improved low-frequency radiation model for smooth finite reflectors. The improved low-frequency model is suggested in two forms for implementation in geometric simulations. The final project in this dissertation uses BEM to investigate the sound field around nonplanar reflectors. The author has added convex edges rounded away from the source side of a finite smooth reflector to minimize coloration of reflections caused by boundary-wave interference. [Copies may be obtained from Jonathan Rathsam, jrathsam@gmail.com]
Experimental investigation of an American five-string banjo
Authors: Stephey Laurie A. , Moore Thomas R.
Published: November 2008

An experimental investigation of an American five-string banjo is reported. The acoustic spectra of the strings are analyzed and it is found that in many ways banjo strings behave in a manner similar to those on a piano. The terminating impedance presented to the strings at the bridge is reported and it is found to be generally much lower than the characteristic impedance of the strings. It is also shown that, for a properly tuned banjo, the mode shapes of the membrane are symmetric about the center even though there is a large asymmetric force due to the off-center placement of the bridge. Finally, high-speed electronic speckle-pattern interferometry was used to study the motion of the membranic head after a string is plucked, and it is found that the motion is dominated by a rocking motion of the bridge.
The role of temporal cues in word identification by younger and older adults: Effects of sentence context
Authors: Gordon-Salant Sandra , Yeni-Komshian Grace , Fitzgibbons Peter
Published: November 2008

Prior investigations, using isolated words as stimuli, have shown that older listeners tend to require longer temporal cues than younger listeners to switch their percept from one word to its phonetically contrasting counterpart. The extent to which this age effect occurs in sentence contexts is investigated in the present study. The hypothesis was that perception of temporal cues differs for words presented in isolation and a sentence context and that this effect may vary between younger and older listeners. Younger and older listeners with normal-hearing and older listeners with hearing loss identified phonetically contrasting word pairs in natural speech continua that varied by a single temporal cue: voice-onset time, vowel duration, transition duration, and silent interval duration. The words were presented in isolation and in sentences. A context effect was shown for most continua, in which listeners required longer temporal cues in sentences than in isolated words. Additionally, older listeners required longer cues at the crossover points than younger listeners for most but not all continua. In general, the findings support the conclusion that older listeners tend to require longer target temporal cues than younger normal-hearing listeners in identifying phonetically contrasting word pairs in isolation and sentence contexts.
A resonance shift prediction based on the Boltzmann–Ehrenfest principle for cylindrical cavities with a rigid sphere
Authors: Santillan Arturo O. , Cutanda-Henríquez Vicente
Published: November 2008

An investigation on the resonance frequency shift for a plane-wave mode in a cylindrical cavity produced by a rigid sphere is reported in this paper. This change of the resonance frequency has been previously considered as a cause of oscillational instabilities in single-mode acoustic levitation devices. It is shown that the use of the Boltzmann–Ehrenfest principle of adiabatic invariance allows the derivation of an expression for the resonance frequency shift in a simpler and more direct way than a method based on a Green’s function reported in literature. The position of the sphere can be any point along the axis of the cavity. Obtained predictions of the resonance frequency shift with the deduced equation agree quite well with numerical simulations based on the boundary element method. The results are also confirmed by experiments. The equation derived from the Boltzmann–Ehrenfest principle appears to be more general, and for large spheres, it gives a better approximation than the equation previously reported.
Study of an automated procedure for a Dutch sentence test for the measurement of the speech reception threshold in noise
Authors: Terband Hayo , Drullman Rob
Published: November 2008

A procedure was developed for the automated measurement of the speech reception threshold in stationary noise (SRTn), which can be administered by the subjects themselves using a computer. The procedure was based on the SRTn test for Dutch developed by Plomp and Mimpen [(1979). “Improving the reliability of testing the speech reception threshold for sentences,” Audiology, 18, 43–52]. Because in the automated procedure the responses were entered on a keyboard, the question of how to deal with typing and spelling errors played a key role. At first the possibility of scoring on keywords only was examined. An experiment was conducted in which the adaptive procedure was varied. Results showed that the combination of scoring each keyword separately and a fixed scheme of the adaptation of the signal-to-noise ratio throughout the procedure yields the highest test-retest reliability. Subsequently, the collection and verification of responses using a keyboard were examined. Two different algorithms were developed and evaluated against the traditional task of verbal repetition and response verification by an experimenter. The results indicated a preference for verification by dynamic alignment over a spelling checker approach. In conclusion, the results show that it is possible to automate the test procedure while maintaining sufficient reliability.
Observations of clustering inside oceanic bubble clouds and the effect on short-range acoustic propagation
Authors: Weber Thomas C.
Published: November 2008

It has recently been shown [Weber, T. C. et al. (2007). “Acoustic propagation through clustered bubble clouds,” IEEE J. Ocean. Eng. 32, 513–523] that gas bubble clustering plays a role in determining the acoustic field characteristics of bubbly fluids. In particular, it has been shown that clustering changes the bubble-induced attenuation as well as the ping-to-ping variability in the acoustic field. The degree to which bubble clustering exists in nature, however, is unknown. This paper describes a method for quantifying bubble clustering using a high frequency (400kHz) multibeam sonar, and reports on observations of near-surface bubble clustering during a storm (14.6m∕s wind speed) in the Gulf of Maine. The multibeam sonar data are analyzed to estimate the pair correlation function, a measure of bubble clustering. In order to account for clustering in the mean acoustic field, a modification to the effective medium wave number is made. With this modification, the multibeam sonar observations are used to predict the effect of clustering on the attenuation of the mean field for short-range propagation (1 m) at frequencies between 10 and 350kHz. Results for this specific case show that clustering can cause the attenuation to change by 20%–80% over this frequency range.
Transient evoked otoacoustic emission input/output function and cochlear reflectivity: Experiment and model
Authors: Sisto Renata , Moleti Arturo
Published: November 2008

The complex input/output function of transient evoked otoacoustic emissions is evaluated at different stimulus levels. The experimental response functions were best fitted to the reflectivity functions predicted by theoretical one-dimensional transmission-line models in the perturbative limit. Along with the otoacoustic emission sources usually considered, linear reflection from roughness (place-fixed) and nonlinear distortion (wave-fixed), a wave-fixed scattering potential is also considered, associated with the breaking of the scale-invariance symmetry, as a new additional mechanism for otoacoustic emission generation. A good fit was obtained, across stimulus level and frequency, for roughness, and not for nonlinear distortion, nor for scale-invariance violation. The phase-gradient delay of the same transient evoked otoacoustic emissions was consistent with the latency measured using a wavelet time-frequency technique, at all stimulus levels and frequencies. The results suggest that cochlear reflectivity is dominated by a component with a rapidly rotating phase, at all stimulus levels, in apparent contradiction with the usual assumption that, at high stimulus levels, a significant contribution to the transient evoked otoacoustic response should come from nonlinear distortion. Possible interpretations of this phenomenology are critically reviewed and discussed, considering the theoretical uncertainties and the limitations of the experimental technique.
Temporal organization of English clear and conversational speech
Authors: Smiljanić Rajka , Bradlow Ann R.
Published: November 2008

This study investigated the effect of hyperarticulated, intelligibility-enhancing clear speech on temporal characteristics as reflected in number, durations, and variability of consonant and vowel intervals in sentence- and paragraph-length utterances. The results of sentence-in-noise listening tests showed a consistent clear speech intelligibility gain across the utterances of varying complexity indicating that the talkers successfully maintained clear speech articulatory modifications throughout longer stretches of speech. The acoustic analysis revealed that some temporal restructuring accompanied changes in speaking style. This temporal restructuring was observed in the insertion of consonant and vowel segments that were dropped or coarticulated in conversational speech and in an increase in the number of prosodic phrases for clear speech. Importantly, coefficients of variation (variation of consonantal and vocalic intervals normalized for changes in speaking rate) for both consonantal and vowel intervals remained stable in the two speaking styles. Overall, these results suggest that increased intelligibility of clear speech may be attributed to prosodic structure enhancement (increased phrasing and enhanced segmentability) and stable global temporal properties.
Voice onset time of Korean stops as a function of speaking rate.
Authors: Oh Eunjin
Published: November 2008

This study aimed to explore the effects of varying speaking rate on voice onset time (VOT) of stops in Korean and to see whether contrasts among stop categories are maintained despite these variations. Plain, tense, and aspirated stops in /CVn/ words (C = three stop places, V = three vowels) in a carrier phrase were examined at both normal and fast rates, which were controlled by alternating phrases on a computer screen at intervals of 2 s and 1 s, respectively. Results revealed that plain and aspirated stops moved toward smaller VOT values, while tense stops did not significantly change as a function of rate. These results are in accordance with Kessinger and Blumstein [J. Phonetics 25, 143–168 (1997)], who found that long-lag and prevoiced categories shifted toward short-lag values at a fast rate in Thai, French, and English. Overlap in VOT ranges between plain and aspirated stops often occurred even at the normal rate, although the degree of overlap was larger at the fast rate, indicating that phonetic cues other than VOTs play a critical role in characterizing the stop categories in Korean. However, VOTs of tense and plain stops generally did not overlap under either rate condition.
MINING FREQUENT TEMPORAL PATTERNS IN INTERVAL SEQUENCES
Authors: KEMPE STEFFEN , HIPP JOCHEN , LANQUILLON CARSTEN , KRUSE RUDOLF
Published: November 2008

Recently a new type of data source came into the focus of knowledge discovery from temporal data: interval sequences. In contrast to event sequences, interval sequences contain labeled events with a temporal extension. However, existing algorithms for mining patterns from interval sequences proved to be far from satisfying our needs. In brief, we missed an approach that, at the same time, defines support as the number of pattern instances, allows input data that consists of more than one sequence, implements time constraints on a pattern instance, and counts multiple instances of a pattern within one interval sequence. In this paper we propose a new support definition which incorporates these properties. We also describe FSMSet, an algorithm that employs the new support definition, and demonstrate its performance on field data from the automotive business.
AN INTELLIGENT TECHNOLOGY BASED METHOD FOR INTERPRETING SENSORY EVALUATION DATA PROVIDED BY MULTIPLE PANELS
Authors: ZHOU BIN , ZENG XIANYI , KOEHL LUDOVIC , DING YONGSHENG
Published: November 2008

This paper presents an intelligent technology based method for analyzing and interpreting sensory data provided by multiple panels in evaluation of industrial products. In order to process the uncertainty existing in these sensory data, we first transform all sensory data on an unified optimal scale. Based on these normalized data sets, we compute the dissimilarities or distances between different panels and between different evaluation terms used by them, defined according to the degree of consistency of data variation. The obtained distances are then transformed into fuzzy numbers for physical interpretation. These fuzzy distances permit to characterize the evaluation behaviour of each panel and the quality of the evaluation terms used. Also, based on a Genetic Algorithm with punishment policy and the dissimilarity between terms, we develop a procedure for interpreting terms of one panel using those of another panel. This method has been applied to the fabric hand evaluation for a number of samples of knitted cotton in order to identify consumers' preference of different populations.
SYNTHESIS AND CHARACTERIZATION OF POLY(PHTHALAZINONE ETHER NITRILE) COPOLYMERS WITH HYDROPHOBIC SURFACE
Authors: DONG L. M. , LIAO G. X. , LIU C. , YANG S. S. , JIAN X. G.
Published: November 2008

Poly(phthalazinone ether nitrile) (PPEN) block copolymers containing polysiloxane were prepared so as to create a strongly hydrophobic polymer surface. The copolymers were synthesized from eugenol end-capped polydimethylsiloxane (PDMS) and fluoro-terminated PPEN oligomers by the aromatic nucleophilic substitution polycondensation in the presence of dimethyl sulfoxide/o-dichlorobenzene and K 2 CO 3 as solvents and catalyst, respectively. The resultant copolymers were characterized by FTIR, 1 H NMR, and gel permeation chromatography. XPS analysis results indicated that the copolymer film had a very rich PDMS segment surface. Atomic force microscopy further showed that there existed a continuous PDMS phase on the copolymer surface and PPEN as the dispersive particles was dispersed at diameters between 0.1 and 0.3 nm. The enrichment of PDMS in the copolymer surface could be responsible for an increase of surface water repellency (113.4°).
LOW ENERGY ELECTRON INDUCED PLASMON EXCITATIONS IN THE ORDERING Pt80Co20(111) ALLOY SURFACE
Authors: VASYLYEV M. A. , TINKOV V. A.
Published: November 2008

Surface and bulk plasmon excitations from the ordering Pt 80 Co 20(111) alloy surface are studied by means electron energy loss spectroscopy in the low energy range of the primary electron energy E0. Deviation of the plasmon excitations from the theoretical value was found for Pt , Co metals, and Pt 80 Co 20(111) alloy as calculated in the free-electron gas model. For the ordered alloy, the bulk plasmon energy is 2–3 eV more than for the disordered alloy, whereas the difference for surface plasmon energy is 4–7 eV in the range E0 = 150–800 eV. The ration of intensity lines of plasmons η from E0 was investigated for the (dis)ordered state of the Pt 80 Co 20(111) alloy surface. For the ordered alloy, η has prolonged dependence from energy E0 in comparison with the disordered alloy. The relationship between layer-by-layer surface concentration and surface plasmon damping was observed.
SIZE-DEPENDENT ELASTIC MODULUS AND FRACTURE TOUGHNESS OF THE NANOFILM WITH SURFACE EFFECTS
Authors: GUO JIAN-GANG , ZHOU LI-JUN , ZHAO YA-PU
Published: November 2008

The effective elastic modulus and fracture toughness of the nanofilm were derived with the surface relaxation and the surface energy taken into consideration by means of the interatomic potential of an ideal crystal. The size effects of the effective elastic modulus and fracture toughness were discussed when the thickness of the nanofilm was reduced. And the dependence of the size effects on the surface relaxation and surface energy was also analyzed.
Three-Dimensional Modeling of the Heat-Affected Zone in Laser Machining Applications
Authors: Beresna Martynas , Gertus Titas , Tomašiūnas Rolandas , Misawa Hiroaki , Juodkazis Saulius
Published: November 2008

Thermal load as well as its three-dimensional (3D) spatial distribution
has been estimated inside representative materials: glass (low thermal
diffusion), silicon (semimetal properties), and sapphire (a crystalline dielectric
of a high thermal conductivity) for typical laser processing and
direct laser writing applications. The 3D temperature distribution allows
to calculate thermal stress around the focal region. This provides an
assessment tool for optimization of laser microprocessing conditions for
controlled laser dicing and cutting applications.
Short- and Long-Term Prognosis among Veterans with Neurological Disorders and Subsequent Lower-Extremity Amputation
Authors: Prvu-Bettger Janet A. , Bates Barbara E. , Bidelspach Douglas E. , Stineman Margaret G.
Published: November 2008

Background: Although comorbid neurological conditions are not uncommon for individuals undergoing lower-extremity (LE) amputation, short- and long-term prognosis is unclear. Methods: This cohort study on the survival of United States veterans with LE amputations examined the association between different preexisting neurological conditions and short- and long-term (in-hospital and within 1-year of surgical amputation) mortality. χ2 and t test statistics compared baseline characteristics for patients with and without neurological disorders. Multiple logistic regression and Cox proportional hazard models were used to examine short- and long-term survival and identify predictors limited to the subset of those with neurological conditions adjusting for age, amputation level and etiology, and co-morbidities. Results: Of 4,720 patients, 43.3% had neurological disorders documented. Most prevalent were stroke or hemiparesis (18.3%) and peripheral nervous system (PNS) disorders (20.3%). Among patients with neurological conditions, those with a PNS disorder or spinal cord injury (or paralysis) were significantly less likely to die in hospital and within 1 year (p < 0.05) when compared to the other types of neurological condition groups including stroke (or hemiparesis), cerebral degenerative diseases, movement disorders and autonomic disorders. Conclusions: The high prevalence of preexisting neurological disorders among LE amputees and the varying effect of different conditions on risk of mortality highlights the need to further characterize the diverseness of this understudied subpopulation. While preexisting spinal cord injury and PNS disorders appear to carry a decreased risk among amputees, those with central nervous system disorders have comparatively greater mortalities.
Carbon Dioxide Laser Endoscopic Diverticulotomy for Zenker’s Diverticulum: Results and Complications in a Consecutive Series of 40 Patients
Authors: Helmstaedter Victor , Engel Alexander , Huttenbrink Karl-Bernd , Guntinas-Lichius Orlando
Published: November 2008

Background: Numerous studies regarding CO2 laser endoscopic diverticulotomy for the treatment of Zenker’s diverticulum exist. They show differences in complications, hospitalization time and postoperative treatment. Objectives: We report our experiences and work out recommendations for postoperative care. Methods: All charts of patients who were treated for Zenker’s diverticulum at the University Department of Otolaryngology, Cologne, Germany, between 1983 and 2003, were reviewed retrospectively. Results: The median age was 58 years. Postoperatively, patients were fed nonorally and received postoperative antibiotic treatment. One patient developed mediastinitis and 3 patients a rise in body temperature. A control radiography disclosed pharyngeal leakages in 3 patients. Overall morbidity averaged 10%. Conclusion: To avoid severe complications we recommend postoperative antibiotic treatment and parenteral feeding. In comparison to the stapler-assisted technique the use of the CO2 laser allows a good view at the diverticular wall throughout the procedure. The transcervical technique should be reserved for cases of anatomic abnormalities or for complicated revision surgeries.
Citrulline Blood Levels as Indicators of Residual Intestinal Absorption in Patients with Short Bowel Syndrome
Authors: Santarpia Lidia , Catanzano Francesca , Ruoppolo Margherita , Alfonsi Lucia , Vitale Dino Franco , Pecce Rita , Pasanisi Fabrizio , Contaldo Franco , Salvatore Francesco
Published: November 2008

Plasma citrulline is known to be a marker of absorptive enterocyte mass in humans. We evaluated whether citrulline and other blood amino acids are indicators of residual small intestinal length and therefore potential predictors of dependence on parenteral nutrition in the long term. We studied 25 patients with short bowel syndrome (SBS) after at least 18 months since last digestive circuit modification; 24 of them were again evaluated 1 year later. Ten patients were weaned off parenteral nutrition and 15 were dependent on parenteral nutrition. Fifty-four healthy volunteers (28 women and 26 men) served as controls. Amino acid levels were determined on serum with high-performance liquid chromatography (HPLC) as well as on blood and serum with tandem mass spectrometry analysis. Five amino acids (citrulline, leucine, isoleucine, valine and tyrosine) were significantly lower in all SBS patients than in controls, whereas glutamine, measured only by HPLC, was significantly higher. Nevertheless, only serum citrulline measured with HPLC was significantly related to small bowel length. We conclude that HPLC remains the reference methodology to evaluate blood or serum amino acid levels in adult population with SBS.
Relation of Hemoglobin to Level of Cognitive Function in Older Persons
Authors: Shah Raj C. , Wilson Robert S. , Tang Yuxiao , Dong Xinqi , Murray Anne , Bennett David A.
Published: November 2008

Background: While decreased hemoglobin concentration is common in the elderly, the relationship of the entire range of hemoglobin concentrations with cognitive function is not well understood. Methods: Cross-sectional analyses were conducted utilizing data from community-dwelling, older persons participating in the Rush Memory and Aging Project. Proximate to first available hemoglobin measurement, 21 cognitive tests were administered to measure global cognitive function along with semantic memory, episodic memory, working memory, perceptual speed and visuospatial abilities. Results: For 793 participants without clinical dementia, stroke or Parkinson’s disease, the mean age was 81.0 years (SD = 7.2); 595 (75%) were women, and 94% were white. The mean hemoglobin concentration was 13.3 g/dl (SD = 1.3). 17% of the cohort had anemia. Using linear regression models adjusted for age, education, gender, body mass index, mean corpuscular volume and glomerular filtration rate, both low and high hemoglobin levels were associated with lower global cognitive function (parameter estimate = –0.015, SE = 0.007, p = 0.019). Low and high hemoglobin levels were associated with worse performance on semantic memory (parameter estimate = –0.201, SE = 0.008, p = 0.010) and perceptual speed (parameter estimate = –0.030, SE = 0.010, p = 0.004), but not the other specific cognitive functions. Conclusions: Low and high hemoglobin concentrations in older persons are associated with a lower level of cognitive function in old age, particularly in semantic memory and perceptual speed.
Smoking Status over Two Years in Patients with Multiple Sclerosis
Authors: Marrie Ruth Ann , Cutter Gary , Tyry Tuula , Campagnolo Denise , Vollmer Timothy
Published: November 2008

Background: Smoking increases the risk of multiple sclerosis (MS) and possibly disease progression. The reliability of self-reported smoking status is unknown in MS. We assessed the reliability of self-reported smoking status among participants in the North American Research Committee on Multiple Sclerosis (NARCOMS) Registry. Methods: In 2004 and 2006, NARCOMS participants reported smoking status using Behavioral Risk Factor Surveillance Survey questions. We compared responses from 5,458 participants answering both questionnaires. We measured agreement regarding smoking status (ever/current) using a κ coefficient, and agreement for ages of starting and quitting smoking, and number of cigarettes smoked using an intraclass correlation coefficient (ICC). Results: In 2004, 2,885 (53.4%) participants reported ever smoking. The κ coefficient for ever smoking was 0.90 (95% confidence interval, CI: 0.89–0.92) and for current smoking 0.92 (95% CI: 0.90–0.94). The ICC for age at starting smoking was 0.73 (95% CI: 0.71–0.75) and for age at quitting smoking 0.90 (95% CI: 0.89–0.91). African-Americans, younger participants and those of lower socioeconomic status were less reliable. Depressed participants reported current smoking status less consistently (odds ratio: 0.51; 95% CI: 0.39–0.67). Conclusions: NARCOMS participants reliably report smoking status. The impact of depression on reliability of self-reported smoking status needs re-evaluation.
Plasma Renin Activity, Renin Substrate and Angiotensin II in the Isolated Dog Kidney Preparation
Authors: Staroukine M. , Vanherweghem J.L. , Ducobu J. , d’Hollander A. , Verniory A.
Published: November 2008

Plasma angiotensin II, renin activity and renin substrate concentration were measured repeatedly during 26 isolated dog kidney perfusion experiments. Plasma renin activity increased early, renin substrate concentration fell rapidly and plasma angiotensin II concentration rose markedly during the perfusion. Despite very high angiotensin II levels a progressive vasodilatation was observed. On the other hand the fall of renin substrate concentration was too important to be accounted for only by the plasma renin activity suggesting an intrarenal pathway of renin substrate consumption.
Effect of ACTH and Adrenal Corticosteroids on Renal Function in Sheep
Authors: Whitworth Judith A. , Coghlan John P. , Denton Derek A. , Fan James S.K. , Humphery Timothy J. , McDougall John G. , Scoggins Bruce A.
Published: November 2008

The effects of administration of ACTH and the major ovine adrenal steroids on renal function in conscious sheep were examined. Glomerular filtration rate and effective renal plasma flow increased with ACTH to 159 and 168% of control and with combined steroid infusion to 153 and 173%, respectively. Filtration fraction fell, absolute tubular sodium reabsorption was increased and glomerulo-tubular balance preserved. The similarity of changes in renal function suggests that these changes are not responsible for the greater blood pressure rise observed with ACTH treatment.
Interrelationship between Acetylcholine and Prostaglandins in the Control of Sodium Excretion and Renin Secretion in Anesthetized Dogs
Authors: Yun John C.H. , Kelly Gerald D. , Bartter Frederic C. , Wong Harry Y.C.
Published: November 2008

Renal function in both acetylcholine (Ach)-infused and noninfused kidneys was examined in both control and indomethacin-treated dogs anesthetized with pentobarbital. Infusion of ACh into the left renal artery of control dogs produced a sustained diuresis and natriuresis without any change in renin secretion. Sodium and potassium excretion from the right kidney showed either a slight decrease or no change. In the dogs pretreated with indomethacin, infusion of ACh into the left renal artery produced a diuresis and natriuresis which could not be sustained despite continued infusion of ACh. Both left renal vein and arterial plasma renin activity showed large increases during the infusion of ACh. Furthermore, when the diuretic and natriuretic response to ACh from the left kidney was diminishing, there was an increase in sodium and potassium excretion from the right kidney. Neither beta-receptor blockade with propranolol nor renal denervation 7-10 days previously could restore the diuretic and natriuretic response to ACh in indomethacin-treated dogs.
Characterization of the Renin-Angiotensin System in the Isolated Perfused Rat Kidney
Authors: Epstein Murray , Flamenbaum Walter , Loutzenhiser Rodger
Published: November 2008

Most previous studies using the isolated perfused kidney model to assess the mechanisms governing renin release have utilized single-point determinations of media renin content as an estimate of renin release rate. In the present study the dynamics of renin release were examined under standardized conditions of perfusion, with simultaneous evaluations of changes in renal function. Media samples were collected at 5-min intervals. Renin release rate was characterized by an initial progressive increase which achieved a constant value of 67 ng/ h/min/g only after 45 min of perfusion. Consequently, the accumulation of renin within the media does not become linear until 45 min of perfusion. Simultaneous determinations of various parameters of renal function disclosed that neither GFR, renal sodium handling nor indices of distal delivery correlated with renin release. However, the renin-angiotensin system is not physiologically intact since the standard perfusate utilized in the present study was demonstrated to lack both renin substrate and converting enzyme. The present studies demonstrate that renin release is curvilinear and that experimental errors may occur if sampling is not restricted to the stable phase of perfusion.
Effects of Kallikrein Inhibition with Aprotinin on Intrarenal Hemodynamics and Urinary Prostaglandin Excretion in Control and Saline-Loaded Conscious Rats
Authors: Kramer Herbert J. , Moch Thomas , Düsing Rainer
Published: November 2008

In conscious rats inhibition of kallikrein formation with aprotinin suppressed urinary prostaglandin (PG) E2 excretion. This was associated with a decrease in inner cortical perfusion in the absence of changes in GFR or hippuran clearance. During acute expansion of the extracellular fluid volume (ECFV) with isotonic saline PGE2 excretion significantly increased but was suppressed during stable ECFV expansion. With ECFV expansion GFR increased, while total and regional cortical perfusion remained unchanged. Aprotinin suppressed the early rise in PGE2 excretion and reduced GFR and hippuran clearance as a result of decreased outer cortical perfusion. It is suggested that integrity of the kinin-prostaglandin system represents an important prerequisite for the functional adaptation of the kidney to acute expansion of the ECFV with isotonic saline.
Influence of Dietary Linoleic Acid Content on the Cytoplasmic Granularity of Renomedullary Interstitial Cells
Authors: Somova Liliana , Jurukova Zanka , Hoffmann Peter , Förster Werner
Published: November 2008

A study of the influence of different diets (rich and deficient in polyunsaturated fatty acids) and of indomethacin on the mean count of renomedullary interstitial cell (RIC) lipid granules was undertaken. A correlation between dietary linoleic acid (LA) content (the main precursor of endogenous prostaglandin biosynthesis) and the number of granules in RIC was demonstrated: in comparison to the salt-loaded rats fed standard pellet diet, the number of RIC lipid granules in salt-loaded rats fed LA in excess increased, while in salt-loaded rats on LA-deficient diet the RIC granularity tended to decrease. Indomethacin treatment caused an increase in RIC granularity in salt-loaded rats fed a standard pellet diet and in those fed LA in excess, but had no effect in salt-loaded rats fed LA-deficient diet.
Type IV Collagen Is a Heteropolymer with the Formula C2D
Authors: Trüeb B. , Odermatt B.F. , Sahu A.P. , Spiess M. , Rüttner J.R. , Winterhalter K.H.
Published: November 2008

Native type IV collagen was purified from bovine kidney cortex homogenate by a method involving pepsin-solubilization and heat gelation. The near homogenous protein has a molecular weight of ∼ 380K and the chain composition C2D. The subunits are linked by disulfïde bridges.
Glomerular Lysosomal Enzymes in Aminonucleoside Nephrosis
Authors: Velosa J.A. , Shah S.V. , Ou S.-L. , Abboud H.E. , Dousa T.P.
Published: November 2008

Lysosomal hydrolases produce degradation of glomerular basement membrane and may play a key role in catabolism of glycoproteins of extracellular matrix in glomeruli. Therefore we investigated activities of some lysosomal enzymes and stability of lysosomes in glomeruli of normal and nephrotic rats. Nephrosis was induced in rats by single injections of puromycin aminonucleoside. In glomeruli from nephrotic rats we found lower activities of β-fucosidase and arylsulfatase, but activity of acid phosphatase was higher compared with control rats. Osmotic stability of lysosomes measured by release of β-glucuronidase was decreased in nephrotic rats. Abnormal activity of lysosomal enzymes and altered physiology of lysosomes in glomeruli may be a pathogenic factor in the altered glycoprotein metabolism in nephrotic syndrome and perhaps also in other glomerular diseases.
A Model for the Glomerular Filter
Authors: Schurer W. , Fleuren G.J. , Hoedemaeker P.J. , Molenaar I.
Published: November 2008

The model for the glomerular filter presented here is based on the relationship between basement membrane collagen and fibrillar collagen. The glomerular basement membrane collagen is produced by the epithelial cell and present on its surface in a staggered organization as in fibrillar collagen. Binding and aggregation of the collagen molecules with a matrix protein results in a large ( ± 50 nm) meshwork controlled by collagen molecules and bound to the cell surface. Because the matrix proteins bind GAGs, the aggregates are recognizable as anionic sites. A continued production of glomerular basement membrane material will cause a movement towards the endothelial side accompanied with a degradation. This degradation results in a loss of carbohydrates, digesting of α-molecules in the triple helices and a loss of anionic sites. The loss of carbohydrates leads to cross-linking and narrowing of the meshes in the direction of the endothelial side of the GBM. Final digestion results in fragmented helices which will pass the GBM and probably be reabsorbed by the epithelial cells or which will pass the slit diaphragm. The slit diaphragm, a staggered collagen structure in plane, functions as a bridge between the epithelial foot processes and is able to regulate the flow and pressure.
Glomerular Basement Membrane Turnover in Young, Old, and Streptozotocin-Diabetic Rats
Authors: Romen W. , Heck T. , Rauscher G. , Lange H.U. , Hempel K.
Published: November 2008

Diabetic and senile glomerulosclerosis consists of thickening of the glomerular basement membranes (GBM) and augmentation of the mesangial matrix. The pathogenesis of these alterations is still controversial. Therefore, an in vivo study of the metabolism and the chemical composition of the GBM in streptozotocin-diabetic and old rats reported here was conducted: The turnover rate of the GBM, determined by the incorporation of labeled hydroxyproline, is prolonged in preparations from diabetic and aging rats. This can be explained by the decreased synthesis and delayed degradation of the GBM material found in both experimental groups. The biochemical analyses of the GBM revealed a higher content of hydroxylated amino acids, especially OH-lys, in the old and diabetic animals. The findings suggest that diabetic and senile glomerulosclerosis results from a prolonged turnover of the GBM and GBM-like material under the altered metabolic conditions investigated in this study.
Influence of the Lectins and Polycation on the Configuration of Renal Podocytes
Authors: Oemar Barry S. , Buss Harro , Hollweg Günter
Published: November 2008

The lectins concanavalin A (Con A), wheat germ agglutinin (WGA), Ricinus communis agglutinin (RCA) I+II and the polycation protamine sulfate were applied directly to renal glomerular podocytes by micropuncture techniques in vivo; others received a control solution. To make visible the distribution of lectins, some rats were given fluorescein isothiocyanate-conjugated Con A. The glomeruli undergoing the micropuncture experiments were labeled and then prepared for SEM and TEM observation, in some cases also for histochemical analysis. Comparatively, the effect of application of the Con A and protamine sulfate solution by intraarterial infusion was studied. The glomeruli of a total of 100 Munich-Wistar rats were studied. Con A and WGA cause varying degrees of’retraction’ of the foot processes of the podocytes when applied using the techniques of micropuncture. Intraarterial infusion of a Con A solution, on the other hand, causes no changes in the podocytes. RCA II, applied for 10 min using micropuncture techniques, causes thickening and swelling of the foot processes as well as the formation of intercellular junctions (‘agglutination’). RCA I, on the other hand, causes no changes in the podocytes of the rat glomerulus. Glomeruli treated with the micropuncture application of the polycation protamine sulfate demonstrate largely ‘agglutination’ and only sometimes localized minimal retraction of the foot processes of the podocytes. The intraarterial infusion of protamine sulfate causes almost exclusively ‘agglutination’ of the podocyte foot processes. Retraction of the podocyte foot processes is probably a result of the active movement of the podocytes, which is in turn induced by attachment of lectines to the lectin receptors in glycocalyx of the podocyte cell membrane. Simple reduction of the polyanions in the podocyte cell membrane by protamine sulfate appears to cause only simple electrostatic interaction which then results in ‘agglutination’ of the podocyte foot processes.
Reproducibility of an Isokinetic Strength-Testing Protocol of the Knee and Ankle in Older Adults
Authors: Hartmann Antonia , Knols Ruud , Murer Kurt , de Bruin Eling D.
Published: November 2008

Background: Muscle power assessed by isokinetic dynamometers has the potential for playing an important role in investigating functional status in older subjects. Researchers and clinicians are interested in the reliability of isokinetic test protocols for the confidential assessment of status, as this affects the interpretation of the results of an intervention program. Objective: The current study investigated the inter- and intrarater reliability of an isokinetic strength-testing protocol of the knee and ankle preceded by a familiarization session. Methods: Twenty-four independently living elderly subjects (6 males, 18 females, mean age 71.2 ± 5.5 years) were assessed 3 times in two test sessions. The main outcomes were the intraclass correlation coefficient, standard error of measurements (SEM) and ratio of limits of agreement (RLOA) for isokinetic knee and ankle contractions, as measured with the Biodex System 3. Results: The intraclass correlation coefficients of the isokinetic variables varied from 0.81 to 0.99 representing ‘good’ to ‘very good’ reliability. Most SEM and RLOA indexes represented acceptable agreement which varied from 6 to 13 and 18 to 37%, respectively. Nonacceptable agreement was found for ankle plantar flexion with SEMs that varied from 14 to 17% and RLOAs from 39 to 48%. Conclusion: The results of this study demonstrate that the Biodex System 3 is a reliable device when used for elderly living independently. The ability of the device to determine a real change in isokinetic ankle and knee contractions is better on a group level than on an individual level. The Biodex System 3 can be employed with confidence in studies to determine the effect of exercise intervention programs on physical activity.
Partial Characterization of a Renotropic Factor
Authors: Gaydos D.S. , Goldin H. , Jenson B. , Gersten D. , Boedeker B. , Bartz C. , Preuss H.G.
Published: November 2008

In 70 experiments, the existence of a circulating renal growth factor was confirmed by 9.3% stimulation of 3H-thymidine into the DNA of renal fragments incubating for 90 min in the presence of sera from 20-hour unilaterallly nephrectomized rats compared to sera from 20-hour sham-operated rats (p < 0.001). Dialysis (7.4%, p < 0.01) or removal of albumin (11.8%, p < 0.001) from sera of both sham-operated and unilaterally nephrectomized rats did not appreciably change the magnitude of the statistically significant stimulation. When albumin-free sera were placed in boiling water for 1-3 min to coagulate protein, the stimulation was still significantly different from control (5%, p < 0.05). Addition of sera from unilaterally nephrectomized rats (20 h) to isolated nuclei, even isolated nuclei removed from growing kidneys (72 h after unilateral nephroctomy), faileds to enhance DNA synthesis significantly.
Ultrastructure of Isolated Basement Membranes in the Acellular Human Renal Cortex
Authors: Carlson Edward C. , Chatterjee Satya N.
Published: November 2008

Transplant quality human kidneys were sliced (≈2 mm thick) and cortical regions further minced to approximately 1 mm3. These samples were treated successively with EDTA and detergents to solubilize cellular materials but leave the extracellular matrix (ECM), including basement membranes (BMs) intact. Resultant acellular cortices bear a remarkable resemblance to their in vivo counterparts. By light microscopy, patent, expanded tubular BM (TBM), peritubular capillary BM (PTCBM) and Bowman’s capsule BM (BCBM) are surrounded by a swollen ECM which is occasionally fibrillar. Glomerular BM (GBM) lacks supporting interstitium but nevertheless remains convoluted and does not collapse. At the level of transmission electron microscopy, the diverse morphological characteristics of each BM type are evident. Random thickness measurements (lamina densa only) show that BCBMs are thickest (≈2,400 nm) followed by TBMs (≈750 nm), GBMs (≈ 335 nm) and PTCBMs (≈ 125 nm). Power transformations to normalize right-sided skew of thickness distribution curves reduce their arithmetic means 3-16%. SEM studies confirm LM and TEM observations that isolated GBMs maintain their free-standing spheroidal shapes and indicate that they may be intrinsically rigid. Moreover, their surface topographical details are preserved. We conclude that the acellular cortex offers a clarified view of renal interstitial morphology and demonstrates structural diversity among major renal BM types. Moreover, it provides a baseline of morphological information on which to assess pathological conditions of renal cortical extracellular matrix.
The Effect of Streptozotocin and Streptozotocin-Induced Diabetes on the Kidney
Authors: Evan Andrew P. , Mong Stephen A. , Gattone Vincent H. , Connors Bret A. , Aronoff George R. , Luft Friedrich C.
Published: November 2008

The study of diabetic nephropathy in experimental animals generally relies on the chemical induction of the diabetic state. Streptozotocin is commonly employed to that end; however, streptozotocin has an inherent nephrotoxic potential. We studied the effects of both streptozotocin, and diabetes on the kidneys of rats given streptozotocin 60 mg/kg, which was sufficient to induce severe diabetes. Our studies, which utilized both transmission and scanning electron microscopy, considered the pharmacokinetics of streptozotocin in renal tissue, as well as the effect of insulin treatment. Renal tissue kinetics were altered by occluding the renal hilum of one kidney during, and for 5 min after, the administration of streptozotocin. We found that, in contrast to alloxan, streptozotocin caused no detectable renal injury at the dose employed. Previously described renal epithelial papillomas were identified, and were not influenced by altering the renal tissue kinetics of the drug. We conclude that no ‘protection’ procedure is necessary for the kidney when the streptozotocin model of diabetes is employed. In this regard streptozotocin may have greater utility than alloxan.
Effects of Natriuretic Fractions of Human Urine on the Isolated Anococcygeus Muscle of the Rat
Authors: Chakravarty B. , Mills I.H. , Callingham B.A.
Published: November 2008

Freeze-dried samples of human urine were reconstituted and chromatographed on Sephadex G-25 columns. Fractions possessing natriuretic activity were eluted after the salts. Application of aliquots of these fractions, after further freeze drying and reconstitution, to the isolated anococcygeus muscle of the rat produced dose-dependent contractions of this smooth muscle. The potency of these samples in causing contractions was positively correlated with their ability to cause natriuresis in water-loaded conscious rats. Use of selective antagonists of possible agonistic agents showed that the ability of the samples to contract smooth muscle was not due to catecholamines, acetylcholine, 5-hydroxytryptamine, pros-taglandin E and angiotensin II.