bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic properties of humpback whale songs
Authors: Au Whitlow W. L. , Pack Adam A. , Lammers Marc O. , Herman Louis M. , Deakos Mark H. , Andrews Kim
Published: August 2006

A vertical array of five hydrophones was used to measure the acoustic field in the vertical plane of singing humpback whales. Once a singer was located, two swimmers with snorkel gear were deployed to determine the orientation of the whale and position the boat so that the array could be deployed in front of the whale at a minimum standoff distance of at least 10m. The spacing of the hydrophones was 7m with the deepest hydrophone deployed at a depth of 35m. An eight-channel TASCAM recorder with a bandwidth of 24kHz was used to record the hydrophone signals. The location (distance and depth) of the singer was determined by computing the time of arrival differences between the hydrophone signals. The maximum source level varied between individual units in a song, with values between 151 and 173dB re 1μPa. One of the purposes of this study was to estimate potential sound exposure of nearby conspecifics. The acoustic field determined by considering the relative intensity of higher frequency harmonics in the signals indicated that the sounds are projected in the horizontal direction despite the singer being canted head downward anywhere from about 25° to 90°. High-frequency harmonics extended beyond 24kHz, suggesting that humpback whales may have an upper frequency limit of hearing as high as 24kHz.
Surface wave modes in rails
Authors: Hesse D. , Cawley P.
Published: August 2006

Rail breaks caused by rolling contact fatigue defects are of growing concern to the railway industry. Very often critical defects cannot be detected reliably by conventional inspection methods. Low-frequency surface waves with a high penetration depth have the potential to overcome such difficulties. In this paper, the properties of surface wave modes in both new and worn rails are investigated and the implications for rail inspection are discussed. The dispersion curves of the dominant surface wave modes were determined up to a frequency of 350kHz using a finite element model and show excellent agreement with experimental data. One surface wave mode was identified to be nondispersive and not significantly affected by cross-section changes due to wear at frequencies above 180kHz. It exhibits a relatively homogeneous energy distribution in the upper half of the rail head and is therefore suitable for inspection purposes. The problem is that there exist several other surface modes with very similar propagation properties. The interference of these multiple modes, which may be generated either directly by the exciter or by mode conversion at defects, means that the received amplitude is position dependent. For this reason, accurate defect sizing will be difficult.
Revisiting the edge resonance for Lamb waves in a semi-infinite plate
Authors: Pagneux Vincent
Published: August 2006

The resonance for the elastic plate with a free edge is studied from the point of view of complex resonance. The variations of the real part and of the imaginary part of the complex resonance frequency as a function of the Poisson ratio ν are determined numerically. The results confirm the real resonance frequency theoretically predicted in I. Roitberg et al., Q. J. Mech. Appl. Math. 51, 1–13 (1998) for a zero Poisson ratio ν1=0, and a real resonance frequency that corresponds to a Lamé mode is discovered for a Poisson ratio ν2=0.2248. It is shown that both real resonance frequencies may exist, at these two particular values of ν, because of the decoupling between the propagating Lamb mode and the set of evanescent Lamb modes.
Effects of age and sequence presentation rate on temporal order recognition
Authors: Fitzgibbons Peter J. , Gordon-Salant Sandra , Friedman Sarah A.
Published: August 2006

The experiments examined the ability of younger and older listeners to identify the temporal order of sounds presented in tonal sequences. The stimuli were three-tone sequences that spanned two-octave frequency range, and listeners identified random permutations of tone order using labels of relative pitch. Some of the sequences featured uniform timing characteristics, and the sequence duty cycle was varied across conditions to examine the relative influence of tonal durations and intertone interval on recognition performance across a range of sequence presentation rates. Other stimulus sequences featured nonuniform timing with unequal tone durations and intertone intervals. The listeners were groups of younger and older persons with or without hearing loss. Results indicated that temporal order recognition was influenced primarily by sequence presentation rate, independent of tonal duration, tonal interval spacing, or sequence timing characteristics. The performance of older listeners was poorer than younger listeners, but the age-related recognition differences were independent of sequence presentation rate. There were no consistent effects of hearing loss on temporal ordering performance.
Analytical modeling for bulk-micromachined condenser microphones
Authors: Tan Chee Wee , Miao Jianmin
Published: August 2006

The advent of silicon micromachining technology has opened up numerous opportunities for the commercialization of many miniaturized sensors and one of the beneficiaries is the silicon condenser microphone. Simple analytical expressions, such as those formulated by Škvor/Starr for mechanical-thermal noise calculation, are used to describe the mechanical performance of a microelectromechanical system (MEMS) microphone. However, the location effect of acoustic holes is usually not considered on both frequency response and mechanical-thermal noise. In this paper, the theory of a condenser microphone is reviewed and a new analytical modeling method for the MEMS condenser microphones is proposed based on Zuckerwar’s model. With reference to a B&K MEMS microphone, the theoretical results obtained by the modeling method are in very good agreements with those experimental ones reported. It is also concluded that there is an optimum location for acoustic holes in the backplate. Finally, a new design for MEMS microphone with a polarization voltage of 10V is proposed, which has an open-circuit sensitivity of 2.1mV∕Pa (or −54dB ref. 1V∕Pa), a bandwidth of 18kHz, an A-weighted mechanical-thermal noise of 22dBA, and a signal-to-noise ratio of 60dB. This proposed microphone can be easily micromachined by using MEMS technology such as the deep reactive ion etching and wafer bonding technology.
On the modeling of sound propagation over multi-impedance discontinuities using a semiempirical diffraction formulation
Authors: Lam Yiu Wai , Monazzam Mohammad Reza
Published: August 2006

Several approximate extensions of the semi-empirical De Jong model [De Jong et al., J. Sound and Vib. 86, 23–46 (1983)] are considered for the prediction of sound propagation over multiple impedance discontinuities. A limitation in the original formulation of the De Jong model is highlighted and a modified form that overcomes this limitation is derived based on reciprocity. This leads to the development of a model for multiple impedance discontinuities that can be used for the investigation of sound-wave propagation above a mixed, striped soft ground that is created by either porous absorbent strips, embedded grooves, or wells with different depths. The accuracy of the model is validated against the boundary element method. It is then used to evaluate the importance of the imaginary part of the admittance of the ground strips on sound attenuation along welled surface. It is shown that the attenuation performance of a surface with multiple impedance discontinuities is high when the imaginary part of the average admittance is large and negative (with an −iωt convention), but the magnitudes of the attenuation peaks are also substantially affected by diffraction from the impedance discontinuities.
A phenomenological model for sonic crystals based on artificial neural networks
Authors: Fuster-Garcia E. , Romero-García V. , Pérez Juan V. Sánchez , García-Raffi L. M. , Sánchez Pérez Enrique A.
Published: August 2006

A phenomenological model that simulates the acoustic attenuation behavior of sonic crystals is developed in this paper. The input of the model is a set of parameters that characterizes each experimental setup, and the output is a simulation of the associated attenuation spectrum. The model consists of a combination of a multiresolution analysis based on wavelet functions and a set of artificial neural networks. An optimized coupling of these tools allows us to drastically reduce the experimental data needed, and to obtain a fast computational model that can be used for technological purposes.
Multiple scattering between two elastic cylinders and invariants of the time-reversal operator: Theory and experiment
Authors: Minonzio Jean-Gabriel , Prada Claire , Aubry Alexandre , Fink Mathias
Published: August 2006

The decomposition-of-the-time-reversal-operator method is an ultrasonic method based on the analysis of the array response matrix used for detection and characterization. The eigenvalues and the eigenvectors of the time-reversal operator (equivalent to the singular values and the singular vectors of the array response matrix) provide information on the localization and nature of scatterers in the insonified medium. Here, the eigenmodes of the time-reversal operator are studied for two elastic cylinders: The effects of multiple scattering and anisotropic scattering are considered. Analytical expressions for the singular values are established within the isotropic scattering approximation. Then, the comparison with a complete model is presented, putting in evidence the importance of the anisotropy of the scattering. Experiments, carried out at central frequency 1.5MHz on 0.25mm diameter nylon and copper cylinders embedded in water, confirm the theory. In particular, the small cylinder limit and the effect of the dominant quadrupolar normal mode of nylon are discussed.
Vibration and sound signatures of human footsteps in buildings
Authors: Ekimov Alexander , Sabatier James M.
Published: August 2006

The acoustic signature of a footstep is one of several signatures that can be exploited for human recognition. Early research showed the maximum value for the force of multiple footsteps to be in the frequency band of 1–4Hz. This paper reports on the broadband frequency-dependent vibrations and sound pressure responses of human footsteps in buildings. Past studies have shown that the low-frequency band (below 500Hz) is well known in the literature, and generated by the force normal to the ground/floor. The seismic particle velocity response to footsteps was shown to be site specific and the characteristic frequency band was 20–90Hz. In this paper, the high-frequency band (above 500Hz) is investigated. The high-frequency band of the vibration and sound of a human footstep is shown to be generated by the tangential force to the floor and the floor reaction, or friction force. The vibration signals, as a function of floor coverings and walking style, were studied in a broadband frequency range. Different walking styles result in different vibration signatures in the low-frequency range. However, for the walking styles tested, the magnitudes in the high-frequency range are comparable and independent of walking style.
Identification of syllables in noise: Electrophysiological and behavioral correlates
Authors: Kaplan-Neeman Ricky , Kishon-Rabin Liat , Henkin Yael , Muchnik Chava
Published: August 2006

This study was designed to characterize the effect of background noise on the identification of syllables using behavioral and electrophysiological measures. Twenty normal-hearing adults (18–30years) performed an identification task in a two-alternative forced-choice paradigm. Stimuli consisted of naturally produced syllables /da/ and /ga/ embedded in white noise. The noise was initiated 1000ms before the onset of the speech stimuli in order to separate the auditory event related potentials (AERP) response to noise onset from that to the speech. Syllables were presented in quiet and in five SNRs: +15, +3, 0, −3, and −6dB. Results show that (1) performance accuracy, d′, and reaction time were affected by the noise, more so for reaction time; (2) both N1 and P3 latency were prolonged as noise levels increased, more so for P3; (3) /ga/ was better identified than /da/, in all noise conditions; and (4) P3 latency was longer for /da/ than for /ga/ for SNR 0 through −6dB, while N1 latency was longer for /ga/ than for /da/ in most listening conditions. In conclusion, the unique stimuli structure utilized in this study demonstrated the effects of noise on speech recognition at both the physical and the perceptual processing levels.
Results from an autonomous underwater vehicle towed hydrophone array experiment in Nantucket Sound
Authors: Holmes Jason D. , Carey William M. , Lynch James F.
Published: August 2006

Shallow water experiments have been conducted in Nantucket Sound with an autonomous underwater vehicle towed hydrophone array system in an area proximate to that of a previous experiment [Frisk and Lynch, J. Acoust. Soc. Am. 86, 1928–1939 (1989)]. Transmission loss was measured, for frequencies between 220 and 1228Hz in an ocean waveguide, under conditions of an isovelocity water column with an approximate depth of 13m over a sandy-silty bottom. Results obtained at 415Hz show classic isovelocity waveguide phenomena that include interference effects, mode stripping due to modal attenuation, and transmission loss proportional 15 to 10log10(R).
Functional Analysis of the
ATG8
Homologue Ao
atg8
and Role of Autophagy in Differentiation and Germination in
Aspergillus oryzae
Authors: Kikuma Takashi , Ohneda Mamoru , Arioka Manabu , Kitamoto Katsuhiko
Published: August 2006

Autophagy is a well-known degradation system, induced by nutrient starvation, in which cytoplasmic components and organelles are digested via vacuoles/lysosomes. Recently, it was reported that autophagy is involved in the turnover of cellular components, development, differentiation, immune responses, protection against pathogens, and cell death. In this study, we isolated the
ATG8
gene homologue Ao
atg8
from the filamentous fungus
Aspergillus oryzae
and visualized autophagy by the expression of DsRed2-AoAtg8 and enhanced green fluorescent protein-AoAtg8 fusion proteins in this fungus. While the fusion proteins were localized in dot structures which are preautophagosomal structure-like structures under normal growth conditions, starvation or rapamycin treatment caused their accumulation in vacuoles. DsRed2 expressed in the cytoplasm was also taken up into vacuoles under starvation conditions or during the differentiation of conidiophores and conidial germination. Deletion mutants of Ao
atg8
did not form aerial hyphae and conidia, and DsRed2 was not localized in vacuoles under starvation conditions, indicating that Ao
atg8
is essential for autophagy. Furthermore, Ao
atg8
conditional mutants showed delayed conidial germination in the absence of nitrogen sources. These results suggest that autophagy functions in both the differentiation of aerial hyphae and in conidial germination in
A. oryzae
.
Sorting Signals Required for Trafficking of the Cysteine-Rich Acidic Repetitive Transmembrane Protein in
Trypanosoma brucei
Authors: Qiao Xugang , Chuang Bin-Fay , Jin Yamei , Muranjan Madhavi , Hung Chien-Hui , Lee Pei-Tseng , Lee Mary Gwo-Shu
Published: August 2006

In trypanosomatids, endocytosis and exocytosis are restricted to the flagellar pocket (FP). The
c
ysteine-
r
ich
a
cidic repetitive trans
m
embrane (CRAM) protein is located at the FP of
Trypanosoma brucei
and potentially functions as a receptor or an essential component for lipoprotein uptake. We characterized sorting determinants involved in efficient trafficking of CRAM to and from the FP of
T. brucei
. Previous studies indicated the presence of signals in the CRAM C terminus, specific for its localization to the FP and for efficient endocytosis (H. Yang, D. G. Russell, B. Zeng, M. Eiki, and M.G.-S. Lee, Mol. Cell. Biol. 20:5149-5163, 2000.) To delineate functional domains of putative sorting signals, we performed a mutagenesis series of the CRAM C terminus. Subcellular localization of CRAM mutants demonstrated that the amino acid sequence between −5 and −14 (referred to as a transport signal) is essential for exporting CRAM from the endoplasmic reticulum to the FP, and mutations of amino acids at −12 (V), −10 (V), or −5 (D) led to retention of CRAM in the endoplasmic reticulum. Comparison of the endocytosis efficiency of CRAM mutants demonstrated that the sequence from amino acid −5 to −23 (referred to as a putative endocytosis signal) is required for efficient endocytosis and overlaps with the transport signal. Apparently the CRAM-derived sorting signal can efficiently interact with the
T. brucei
μ1 adaptin, and mutations at amino acids essential for the function of the transport signal abolished the interaction of the signal with
T. brucei
μ1, strengthening the hypothesis of the involvement of the clathrin- and adaptor-dependent pathway in trafficking of CRAM via the FP.
Transcriptomic Analysis of Extensive Changes in Metabolic Regulation in
Kluyveromyces lactis
Strains
Authors: Suleau Audrey , Gourdon Pierre , Reitz-Ausseur Joëlle , Casaregola Serge
Published: August 2006

Genome-wide analysis of transcriptional regulation is generally carried out on well-characterized reference laboratory strains; hence, the characteristics of industrial isolates are therefore overlooked. In a previous study on the major cheese yeast
Kluyveromyces lactis
, we have shown that the reference strain and an industrial strain used in cheese making display a differential gene expression when grown on a single carbon source. Here, we have used more controlled conditions, i.e., growth in a fermentor with pH and oxygen maintained constant, to study how these two isolates grown in glucose reacted to an addition of lactose. The observed differences between sugar consumption and the production of various metabolites, ethanol, acetate, and glycerol, correlated with the response were monitored by the analysis of the expression of 482 genes. Extensive differences in gene expression between the strains were revealed in sugar transport, glucose repression, ethanol metabolism, and amino acid import. These differences were partly due to repression by glucose and another, yet-unknown regulation mechanism. Our results bring to light a new type of
K. lactis
strain with respect to hexose transport gene content and repression by glucose. We found that a combination of point mutations and variation in gene regulation generates a biodiversity within the
K. lactis
species that was not anticipated. In contrast to
S. cerevisiae
, in which there is a massive increase in the number of sugar transporter and fermentation genes, in
K. lactis
, interstrain diversity in adaptation to a changing environment is based on small changes at the level of key genes and cell growth control.
Stress-Specific Role of Fission Yeast Gcn5 Histone Acetyltransferase in Programming a Subset of Stress Response Genes
Authors: Johnsson Anna , Xue-Franzén Yongtao , Lundin Maria , Wright Anthony P. H.
Published: August 2006

Gcn5 is a coactivator protein that contributes to gene activation by acetylating specific lysine residues within the N termini of histone proteins. Gcn5 has been intensively studied in the budding yeast,
Saccharomyces cerevisiae
, but the features of genes that determine whether they require Gcn5 during activation have not been conclusively clarified. To allow comparison with
S. cerevisiae
, we have studied the genome-wide role of Gcn5 in the distantly related fission yeast,
Schizosaccharomyces pombe
. We show that Gcn5 is specifically required for adaptation to KCl- and CaCl
2
-mediated stress in
S. pombe
. We have characterized the genome-wide gene expression responses to KCl stress and show that Gcn5 is involved in the regulation of a subset of stress response genes. Gcn5 is most clearly associated with KCl-induced genes, but there is no correlation between Gcn5 dependence and the extent of their induction. Instead, Gcn5-dependent KCl-induced genes are specifically enriched in four different DNA motifs. The Gcn5-dependent KCl-induced genes are also associated with biological process gene ontology terms such as carbohydrate metabolism, glycolysis, and nicotinamide metabolism that together constitute a subset of the ontology parameters associated with KCl-induced genes.
In Vitro Generation of Human High-Density-Lipoprotein-Resistant
Trypanosoma brucei brucei
Authors: Faulkner Sara D. , Oli Monika W. , Kieft Rudo , Cotlin Laura , Widener Justin , Shiflett April , Cipriano Michael J. , Pacocha Sarah E. , Birkeland Shanda R. , Hajduk Stephen L. , McArthur Andrew G.
Published: August 2006

The host range of African trypanosomes is influenced by innate protective molecules in the blood of primates. A subfraction of human high-density lipoprotein (HDL) containing apolipoprotein A-I, apolipoprotein L-I, and haptoglobin-related protein is toxic to
Trypanosoma brucei brucei
but not the human sleeping sickness parasite
Trypanosoma brucei rhodesiense
. It is thought that
T. b. rhodesiense
evolved from a
T. b. brucei
-like ancestor and expresses a defense protein that ablates the antitrypanosomal activity of human HDL. To directly investigate this possibility, we developed an in vitro selection to generate human HDL-resistant
T. b. brucei
. Here we show that conversion of
T. b. brucei
from human HDL sensitive to resistant correlates with changes in the expression of the variant surface glycoprotein (VSG) and abolished uptake of the cytotoxic human HDLs. Complete transcriptome analysis of the HDL-susceptible and -resistant trypanosomes confirmed that VSG switching had occurred but failed to reveal the expression of other genes specifically associated with human HDL resistance, including the serum resistance-associated gene (
SRA
) of
T. b. rhodesiense
. In addition, we found that while the original active expression site was still utilized, expression of three expression site-associated genes (
ESAG
) was altered in the HDL-resistant trypanosomes. These findings demonstrate that resistance to human HDLs can be acquired by
T. b. brucei
.
Fungal Metabolic Model for Tyrosinemia Type 3: Molecular Characterization of a Gene Encoding a 4-Hydroxy-Phenyl Pyruvate Dioxygenase from
Aspergillus nidulans
Authors: da Silva Ferreira Márcia Eliana , Savoldi Marcela , Sueli Bonato Pierina , Goldman Maria Helena S. , Goldman Gustavo H.
Published: August 2006

Mutations in the human HPD gene (encoding 4-hydroxyphenylpyruvic acid dioxygenase) cause hereditary tyrosinemia type 3 (HT3). We deleted the
Aspergillus nidulans
homologue (
hpdA
). We showed that the mutant strain is not able to grow in the presence of phenylalanine and that it accumulates increased concentrations of tyrosine and 4-hydroxyphenylpyruvic acid, mimicking the human HT3 phenotype.
Changes in muscle activity and perceived exertion during exercises performed on a swiss ball
Authors: Marshall Paul , Murphy Bernadette
Published: August 2006

The objective of this study was to determine differences in electromyographic (EMG) activity of prime mover and abdominal muscles while performing squats, push ups, and double leg lowering with a swiss ball. Twelve healthy subjects performed the movements. There was no difference between the surface conditions for muscle activity during the squat exercise; however, individuals had lower perceived exertion for the swiss ball squat. Activity of the triceps and abdominals was highest performing push ups on the swiss ball, whereas the activity of rectus abdominus (RA) only increased during double leg lowering on the swiss ball. Perceived exertion was highest for the push up and leg-lowering exercise performed on the swiss ball. Increased RA activity during double leg lowering can be attributed to its role as a hip flexor, whereas the lack of a rotation aspect to the task prevented increased oblique muscle activity. The swiss ball appears to only increase muscle activity during exercises where the unstable surface is the primary base of support.
Physical activity during treatment in children with leukemia: a pilot study
Authors: Aznar Susana , Webster Anthony L. , San Juan Alejandro F. , Chamorro-Viña Carolina , Maté-Muñoz José L. , Moral Susana , Pérez Margarita , García-Castro Javier , Ramírez Manuel , Madero Luis , Lucia Alejandro
Published: August 2006

The purpose of this pilot study was to measure physical activity (PA) levels in children undergoing treatment for acute lymphoblastic leukemia (ALL) and to compare the results with those from age-matched healthy children. We used the MTI Actigraph accelerometer to determine PA (during a 1 week period) in children (n = 7; age = 4–7 y) undergoing maintenance treatment for ALL and in age-matched controls (n = 7). The number of children accumulating at least 60 min of moderate-to-vigorous physical activity (MVPA) for 5 or more days of the week was 3 for the control group, whereas no children with ALL met this criterion. Significantly lower levels of total weekly time of MVPA were seen in children being treated for ALL (328 ± 107 min) than in controls (506 ± 175 min) (p < 0.05). When weekday data was analyzed, the ALL patients also had significantly lower mean daily times of MVPA (49 ± 23 min vs. 79 ± 25 min). It is thus important that young ALL sufferers are encouraged to participate in appropriate sports, games, and physical activities both in the family and school environments that will prime them with positive attitudes to PA during the critical early years of life.
Effects of physical conditioning on lipids and arachidonic acid metabolites in untrained boys: a longitudinal study
Authors: Stergioulas Apostolos Thomas , Filippou Dimitrios Konstantinos
Published: August 2006

In addition to a variety of lipids, 2 products of the arachidonic acid cascade, prostacyclin and thromboxane, are involved in the pathogenesis of atherosclerosis as a result of their effects on platelet function and on the vascular endothelium. The aim of the present investigation was to ascertain if a sub-maximal 8 week endurance training period followed by a 4 week detraining period would have any effects on high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC), triglycerides (TG), 2,3-dinor-6-keto-prostaglandin F1α(2,3-dinor-6-keto-PGF1α), the urinary metabolite of prostacyclin, 2,3-dinor-thromboxane B2(2,3-dinor-TXB2), the urinary metabolite of thromboxane, and the ratios of TC to HDL-C and of 2,3 dinor-6-keto-PGF1αto 2,3-dinor-TXB2. Thirty-eight boys aged 10–14 were randomly divided into exercise (n = 21) and control (n = 17) groups. The exercise group trained on a bicycle ergometer 4 times/week, 1 h/session, at 80% of their physical working capacity at a heart rate of 170 beats/min (PWC170), for 8 weeks. The control group did not participate in any specific physical exercise program. The results showed that relative to the control group, the exercise group had a significant increase in HDL-C and 2,3-dinor-6-keto-PGF1αconcentrations at the end of the 4th (p < 0.05 and p < 0.001, respectively) and the 8th week (p < 0.01 and p < 0.001) of training, respectively; a significant increase in the 2,3 dinor-6-keto-PGF1α– 2,3-dinor-TXB2ratio (p < 0.05 and p < 0.01 at the same intervals); a significant decrease in TG at the end of the 8th week of training (p < 0.05); and a significant decrease in the TC–HDL-C ratio at the end of the 4th (p < 0.05) and 8th weeks of training (p < 0.001).
Viability of the isolated soleus muscle during long-term incubation
Authors: Alkhateeb Hakam , Chabowski Adrian , Bonen Arend
Published: August 2006

Skeletal muscle metabolism has been examined in perfused hindlimb muscles and in isolated muscle preparations. While long-term viability of the fast-twitch epitrochlearis has been documented with respect to glucose transport, it appears that long-term incubated soleus muscles are less stable when incubated ex vivo for many hours. Therefore, in the present study, we have examined whether the isolated soleus muscle remains metabolically viable for up to 18 h with respect to maintaining ATP and phosphocreatine (PCr) concentrations, carbohydrate and fatty-acid metabolism, insulin signalling, and protein expression. Soleus muscles were incubated in well-oxygenated Medium 199 (M199) supplemented with low concentrations of insulin (14.3 µU/mL) for 0, 6, 12, and 18 h. During this incubating period the concentrations of ATP and PCr were stable, indicating that oxygenation and substrate supply were being maintained. In addition, the concentrations of proglycogen and macroglycogen were not altered, whereas an increase (+30%) in intramuscular triacylglycerol concentration was observed at the end of 18 h of incubation (p < 0.05). Complex molecular processes in the long-term incubated muscles were also stable. This was shown by maintenance of basal as well as insulin-stimulated rates of 3-O-methyl glucose transport, and by the maintenance of protein expression of the glucose transporter GLUT4 and the fatty acid transporters FAT/CD36 and FABPpm. In addition, the insulin-stimulated translocation of GLUT4 to the plasma membrane, which involves a complex signalling cascade, was fully preserved. In conclusion, in well-oxygenated soleus muscles maintained in M199 supplemented with extremely low concentrations of insulin, ATP and PCr concentrations, carbohydrate and fatty acid metabolism, insulin signalling, and protein expression were stably maintained for up to 18 h. This provides for opportunities to examine muscle metabolic function under very highly controlled conditions.
In vivo effect ofTrigonella foenum graecumon the expression of pyruvate kinase, phosphoenolpyruvate carboxykinase, and distribution of glucose transporter (GLUT4) in alloxan-diabetic rats
Authors: Mohammad Sameer , Taha Asia , Akhtar Kamal , Bamezai R.N.K. , Baquer Najma Zaheer
Published: August 2006

Plasma glucose levels are maintained by a precise balance between glucose production and its use. Liver pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK), 2 key enzymes of glycolysis and gluconeogenesis, respectively, play a crucial role in this glucose homeostasis along with skeletal muscle glucose transporter (GLUT4). In the diabetic state, this balance is disturbed owing to the absence of insulin, the principal factor controlling this regulation. In the present study, alloxan-diabetic animals having high glucose levels of more than 300 mmol/L have been taken and the administration of Trigonella seed powder (TSP) to the diabetic animals was assessed for its effect on the expression of PK and PEPCK in liver and GLUT4 distribution in skeletal muscle of alloxan-diabetic rats. TSP treatment to the diabetic animals resulted in a marked decrease in the plasma glucose levels. Trigonella treatment partially restored the altered expression of PK and PEPCK. TSP treatment also corrected the alterations in the distribution of GLUT4 in the skeletal muscle.
Sodium-, chloride-, and mibefradil-sensitive calcium channels in intestinal pacing in wild-type and W/WV mice
Authors: Boddy Geoffrey , Willis A. , Galante G. , Daniel E.E.
Published: August 2006

Pacing of intestinal smooth muscle is driven by a network of cells found in the myenteric plexus called the interstitial cells of Cajal (ICC-MP), which produce a rhythmic pacemaker current. Using intact segments of circular (CM) and longitudinal (LM) muscle from wild-type and W/WV mice, we found that sodium-, chloride-, and mibefradil-sensitive ion channel currents are required for normal pacing to occur. Application of 30 µmol/L and 300 µmol/L lidocaine, 1 mmol/L 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS), 50 nmol/L and 500 nmol/L mibefradil, or low sodium Krebs significantly reduced pacing frequency in LM and CM. However, simultaneously applying DIDS and lidocaine or low sodium Krebs solution did not completely block pacing nor did it have an additive effect. Lidocaine and low sodium Krebs solution also abolished the gradient of pacing frequencies (higher proximally) found throughout the intestine, resulting in a uniform contraction frequency of 30–40/min. In W/WV mice, which lack ICC-MP, application of DIDS and lidocaine had no effect on the robust pacing in LM segments. In conclusion we found that sodium-, chloride-, and mibefradil-sensitive channel activities were required for normal pacing and to maintain the pacing gradient found throughout the intestines in wild-type but not W/WV mice.
Early activation and redistribution of calpain activity in skeletal muscle during hindlimb unweighting and reweighting
Authors: Enns Deborah L. , Belcastro Angelo N.
Published: August 2006

The aims of this study were the following: (i) to determine whether activation of the Ca2+-activated protease, calpain, is an early event during hindlimb unweighting (HU) in skeletal muscle; and (ii) to assess whether calpain activity is greater during reweighting compared with HU alone. Rats were exposed to 12, 24, and 72 h, or 9 d of HU, followed by reweighting for 0, 12, or 24 h. Calpain activities were assayed for total, soluble, and particulate fractions. Total calpain activity was increased in the soleus at all HU time points, whereas activities were elevated in the gastrocnemius only after 9 d of HU. With reweighting, calpain activity remained elevated at all time points for both muscles. In general, reweighting the gastrocnemius increased its calpain activity more than during HU only, whereas reweighting the soleus did not produce additional increases in its calpain activity. The increases in calpain activity were associated with a proportional increase in activity of the particulate (membrane- and protein-associated) fraction. The results suggest that calpain activation is an early event during HU in the soleus, and that the increases in calpain activity in both muscles are associated with a redistribution of activity from cytosolic to particulate fractions.
Magnesium deficiency augments myocardial response to reactive oxygen species
Authors: Manju L. , Nair R. Renuka
Published: August 2006

Magnesium (Mg) deficiency and oxidative stress are independently implicated in the etiopathogenesis of various cardiovascular disorders. This study was undertaken to examine the hypothesis that Mg deficiency augments the myocardial response to oxidative stress. Electrically stimulated rat papillary muscle was used for recording the contractile variation. Biochemical variables of energy metabolism (adenosine triphosphate (ATP) and creatine phosphate) and markers of tissue injury (lactate dehydrogenase (LDH) release and lipidperoxidation), which can affect myocardial contractility, were assayed in Langendorff-perfused rat hearts. Hydrogen peroxide (100 µmol/L) was used as the source of reactive oxygen species. The negative inotropic response to H2O2was significantly higher in Mg deficiency (0.48 mmol Mg/L) than in Mg sufficiency (1.2 mmol Mg/L). Low Mg levels did not affect ATP levels or tissue lipid peroxidation. However, H2O2induced a decrease in ATP; enhanced lipid peroxidation and the release of LDH were augmented by Mg deficiency. Increased lipid peroxidation associated with a decrease in available energy might be responsible for the augmentation of the negative inotropic response to H2O2in Mg deficiency. The observations from this study validate the hypothesis that myocardial response to oxidative stress is augmented by Mg deficiency. This observation has significance in ischemia–reperfusion injury, where Mg deficiency can have an additive effect on the debilitating consequences.
Muscle glucose transport and phosphorylation in type 2 diabetic, obese nondiabetic, and genetically predisposed individuals
Authors: Pendergrass Merri , Bertoldo Alessandra , Bonadonna Riccardo , Nucci Gianluca , Mandarino Lawrence , Cobelli Claudio , DeFronzo Ralph A.
Published: August 2006

Our objectives were to quantitate insulin-stimulated inward glucose transport and glucose phosphorylation in forearm muscle in lean and obese nondiabetic subjects, in lean and obese type 2 diabetic (T2DM) subjects, and in normal glucose-tolerant, insulin-resistant offspring of two T2DM parents. Subjects received a euglycemic insulin (40 mU·m−2·min−1) clamp with brachial artery/deep forearm vein catheterization. After 120 min of hyperinsulinemia, a bolus of d-mannitol/3- O-methyl-d-[14C]glucose/d-[3-3H]glucose (triple-tracer technique) was given into brachial artery and deep vein samples obtained every 12–30 s for 15 min. Insulin-stimulated forearm glucose uptake (FGU) and whole body glucose metabolism (M) were reduced by 40–50% in obese nondiabetic, lean T2DM, and obese T2DM subjects (all P < 0.01); in offspring, the reduction in FGU and M was ∼30% ( P < 0.05). Inward glucose transport and glucose phosphorylation were decreased by ∼40–50% ( P < 0.01) in obese nondiabetic and T2DM groups and closely paralleled the decrease in FGU. The intracellular glucose concentration in the space accessible to glucose was significantly greater in obese nondiabetic, lean T2DM, obese T2DM, and offspring compared with lean controls. We conclude that 1) obese nondiabetic, lean T2DM, and offspring manifest moderate-to-severe muscle insulin resistance (FGU and M) and decreased insulin-stimulated glucose transport and glucose phosphorylation in forearm muscle; these defects in insulin action are not further reduced by the combination of obesity plus T2DM; and 2) the increase in intracelullar glucose concentration under hyperinsulinemic euglycemic conditions in obese and T2DM groups suggests that the defect in glucose phosphorylation exceeds the defect in glucose transport.
Differential regulation of B/K protein expression in proximal and distal tubules of rat kidneys with ischemia-reperfusion injury
Authors: Han Ki-Hwan , Lee U-Young , Jang Yoon-Seong , Cho Yoon Mi , Jang Young Min , Hwang In-A , Ghee Jung Yeon , Lim Sun-Woo , Kim Wan-Young , Yang Chul Woo , Kim Jin , Kwon Oh-Joo
Published: August 2006

Brain/kidney (B/K) protein is a novel double C2-like-domain protein that is highly expressed in rat brain and kidney, but its cellular localization and functional role in the kidney are still undetermined. We examined the cellular localization of B/K protein in the rat kidney under normal and ischemic conditions. Ischemia-reperfusion (I/R) injury was induced by clamping both renal arteries for 45 min, and animals were killed at 1 and 6 h and 1, 2, 3, 5, 7, 14, and 28 days after the reperfusion. Kidney tissues were processed for immunohistochemistry and immunoblot analyses using rabbit anti-B/K polyclonal antibodies. In control kidneys, B/K protein was expressed primarily in distal tubules including the thick ascending limb, distal convoluted and connecting tubules, and collecting duct. Notably, B/K protein was also expressed in the straight portion (S3 segment), but not in the S1 or S2, of proximal tubules, and podocytes of the glomerulus. In rat kidneys with I/R injury, expression of B/K protein was differentially regulated according to the anatomic location. In distal tubules, overall expression of B/K protein was markedly decreased. On the other hand, I/R injury significantly increased B/K protein expression in the S3 segment of the outer medulla as well as in the rat proximal tubular epithelial cell line NRK-52E in vitro. Furthermore, B/K protein was strongly expressed in many exfoliated cells in the lumen and urine. These findings suggest that B/K protein is closely associated with cell death in proximal tubules, which are vulnerable to I/R injury in the kidney.
DOCA/NaCl-induced chronic kidney disease: a comparison of renal nitric oxide production in resistant and susceptible rat strains
Authors: Erdely Aaron , Freshour Gary , Tain You-Lin , Engels Kevin , Baylis Chris
Published: August 2006

Recent studies show nitric oxide (NO) deficiency is both a cause and consequence of chronic kidney disease (CKD). Reduced renal neuronal NO synthase (nNOS) abundance and activity parallel development of CKD with different models in the Sprague-Dawley (SD) rats, whereas Wistar Furth (WF) rats are protected against CKD and show preserved renal NO production. In this study, we compared renal NO in response to DOCA/salt-induced injury between the WF and SD. Studies were conducted on sham WF ( n = 6) and SD ( n = 6) and uninephrectized (UNX)+75 mg DOCA+1% NaCl (WF n = 9; SD n = 10) rats followed for 5 wk. Kidneys were harvested for Western blot, NOS activity, and histology. Other measurements included creatinine clearance and 24-h total NO production and urinary protein excretion. Absolute values of kidney weight were lower in WF than SD rats that showed similar percent increases with UNX+DOCA/NaCl. Proteinuria and decreased creatinine clearance were present in the SD but not the WF rats following UNX+DOCA/NaCl. Glomerular injury was mild in the WF compared with SD rats that showed many globally damaged glomeruli. Although renal nNOS abundance was decreased in both strains (higher baseline in WF), soluble NOS activity was maintained in the WF but significantly reduced in the SD rats. Renal endothelial NOS abundance and membrane NOS activity were unaffected by treatment. In summary, WF rats showed resistance to UNX+DOCA/NaCl-induced CKD with maintained renal NO production despite mild reduction in nNOS abundance. Further studies are needed to evaluate how WF rats maintain renal NO production despite similar changes in abundance as the vulnerable SD strain.
A dogged pursuit of coincidence
Authors: Joris Philip X.
Published: August 2006

This essay looks at the historical significance or two APS papers that are freely available online:

Goldberg JM and Brown PB.

Response of binaural neurons of dog superior olivary complex to dichotic tonal stimuli: some physiological mechanisms of sound localization, J Neurophysiol 32: 613–636, 1969 ( http://jn.physiology.org/cgi/reprint/32/4/613 ).

Yin TCT and Chan J.

Interaural time sensitivity in medial superior olive of cat, J Neurophysiol 64: 465–488, 1990 ( http://jn.physiology.org/cgi/reprint/64/2/465 ).
Responses of Neurons in the Ventral Nucleus of the Lateral Lemniscus to Sinusoidally Amplitude Modulated Tones
Authors: Batra Ranjan
Published: August 2006

Fluctuations in the amplitude of a sound play an important role in our perception of pitch and acoustic space, but their neural analysis has not been fully elucidated. The ventral nucleus of the lateral lemniscus (VNLL) has been implicated in the processing of such temporal features of a sound. This study examines responses of neurons in the VNLL of unanesthetized rabbits to sinusoidally amplitude modulated tones, a type of stimulus that has often been used to investigate encoding of temporal information. Modulation transfer functions of responses were calculated in two ways: based on discharge rates (rMTFs) and on synchronization to the envelope (tMTFs). Among the variety of rMTFs, two types were readily identifiable: flat and band-pass. The responses of neurons exhibiting these types of rMTF differed in several ways. Neurons with flat rMTFs typically had moderate rates of spontaneous activity, sustained responses to short tone bursts, and low-pass or band-pass tMTFs. Neurons with band-pass rMTFs typically had low spontaneous activity, onset responses to short tone bursts, and flat tMTFs. The vast majority synchronized strongly to the modulation envelope. The best modulation frequencies of neurons with band-pass rMTFs extended from 14 to 283 Hz. The presence of neurons with band-pass rMTFs in the VNLL suggests that this nucleus plays a role in converting the temporal code for modulation frequency used in lower structures into a rate-based code for use higher in the auditory pathway. The substantial number of neurons with more complex modulation transfer functions indicates that the VNLL has other functions.
Genetic analysis of the stress-responsive adrenocortical axis
Authors: Solberg Leah C. , Baum Amber E. , Ahmadiyeh Nasim , Shimomura Kazuhiro , Li Renhua , Turek Fred W. , Takahashi Joseph S. , Churchill Gary A. , Redei Eva E.
Published: August 2006

The underlying genetic components contributing to individual variability in functions of the stress-responsive hypothalamic-pituitary-adrenal (HPA) axis are poorly understood. To determine genetic loci mediating three aspects of the adrenocortical function, we conducted a quantitative trait locus (QTL) analysis in the segregating F2 generation of a Wistar Kyoto (WKY) × Fischer 344 (F344) cross, two inbred rat strains that differ in several HPA axis measures. The following three components of adrenocortical function are known to be regulated by different mechanisms that are mediated via suprahypothalamic, hypothalamic, pituitary, and intra-adrenal influences: basal plasma corticosterone (Cort) levels, plasma Cort response to a 10-min restraint stress, and adrenal weight. Genome scans identified a complex genetic architecture for the basal Cort phenotype, including sex and maternal lineage effects. Pairwise interactions were also identified for this trait. We identified three significant and two suggestive QTLs for stress Cort, along with two pairs of interacting loci for this trait. Four highly significant and two suggestive loci were identified for adrenal weight, with no interacting loci. In contrast to basal Cort, no sex- or lineage-dependent QTL were identified for stress Cort or adrenal weight, despite the large sex differences in these phenotypes. We identified three nucleotide alterations in an obvious candidate gene mapped to the most significant QTL for stress Cort, Cort-binding globulin (CBG), one of which is known to alter CBG binding. This analysis confirms that three separate traits regulated by the HPA axis are controlled by multiple, but mainly nonoverlapping, QTLs.
Antisense to Cyclin D1 Inhibits Vascular Endothelial Growth Factor–Stimulated Growth of Vascular Endothelial Cells: Implication of Tumor Vascularization
Authors: Yasui Masayoshi , Yamamoto Hirofumi , Ngan Chew Yee , Damdinsuren Bazarragchaa , Sugita Yurika , Fukunaga Hiroki , Gu Jinyu , Maeda Makiko , Takemasa Ichiro , Ikeda Masataka , Fujio Yasushi , Sekimoto Mitsugu , Matsuura Nariaki , Weinstein I. Bernard , Monden Morito
Published: August 2006

Purpose: Our aim was to determine the effects of cyclin D1 inhibition on tumor-associated neovascularization and endothelial cell growth.

Experimental Design: We have generated adenovirus system for antisense to cyclin D1 (AS CyD1) and evaluated in vitro and in vivo effects. Small interfering RNA against cyclin D1 was also used to analyze cyclin D1 inhibition-associated vascular endothelial growth factor (VEGF) regulation.

Results: The xenografts treated with adenoviral AS CyD1 showed less vessel density and displayed smaller tumor size in colon cancer cell lines HCT116 and DLD1. In vitro studies indicated that AS CyD1 decreased VEGF protein expression in DLD1 but not in HCT116. Cyclin D1 small interfering RNA caused a decrease in VEGF expression at protein and RNA levels in DLD1. A modest decrease was noted in the VEGF promoter activity, with inactivation of the STAT3 transcription factor through dephosphorylation. On the hand, the cyclin D1 inhibition plus STAT3 inhibitor markedly decreased VEGF expression in HCT116, although VEGF did not change by the STAT3 inhibitor alone. In cultures of human umbilical vein endothelial cells (HUVEC), VEGF augmented cyclin D1 expression and cell growth. AS CyD1 significantly inhibited HUVEC growth even in the presence of VEGF. AS CyD1 also significantly suppressed in vitro tube formation in VEGF-treated HUVEC and in vivo macroaneurysm formation in VEGF-treated Matrigel plug.

Conclusions: Our results suggest that cyclin D1 may play a role in the maintenance of VEGF expression and that AS CyD1 could be potentially useful for targeting both cancer cells and their microenvironment of tumor vessels.