bluuebunny/crossref_metadata_2025 huggingface dataset:
Sci‐Fri AM General‐01: X‐Ray Tube Induction Motor Performance in a 1.5 T MRI Fringe Field
Authors: Bracken J , Rowlands J
Published: July 2006

We assessed the performance of the induction motor of a rotating‐anode x‐ray tube in the magnetic fringe field of a clinical MRI scanner. A standard rotating‐anode x‐ray tube insert was placed into the fringe field of a 1.5 T unshielded research MRI scanner. The induction motor in the x‐ray tube was aligned so that the magnetic field lines were in the plane of its stator core. The induction motor of the x‐ray tube was placed in magnetic fields ranging from 0 to 500 G. The magnetic fields were measured with a Model 4048 Gauss meter. The rotation speed of the anode was measured using a strobe light. The power consumed by the motor during operation in the fringe field was measured separately using a PLM‐1 power meter. The anode rotation speed dropped from 3437 +/− 6.8 rpm to 2744 +/− 5.3 rpm when the magnetic fringe field was increased from 0 to 400 G. The average power consumed by the motor increased from 70.5 +/− 0.4 W to 78.2 +/− 0.1 W when the fringe field was increased from 0 to 500 G. This work indicates the feasibility of safely operating an x‐ray tube induction motor in the fringe field of an MRI scanner. Power consumption did not significantly increase and anode rotation speed did not fall below 3000 rpm until a fringe field exceeding 300 G was applied.
Sci‐Fri AM General‐04: High Contrast Imaging Using Orthogonal Bremsstrahlung Beams: An Experimental Study of Radiation Quality
Authors: Sarfehnia A , Jabbari K , Seuntjens J , Podgorsak E
Published: July 2006

Since portal images are created by megavoltage, forward‐directed bremsstrahlung beams, their image quality is inferior to that of images produced by kilovoltage beams. In this study, characteristics of orthogonal bremsstrahlung photons produced by megavoltage electron pencil beams were studied and suitability of their use for improved radiotherapy imaging was evaluated. A 10 MeV electron beam emerging through the research port of a Varian Clinac‐18 linac was made to strike targets of carbon, aluminum and copper. PDD and attenuation measurements of both the forward and orthogonal beams were performed, and experimental results were compared with Monte Carlo‐calculated findings. Images of contrast objects were acquired with Agfa 400 diagnostic films and their contrast levels were analyzed. Photon yield and effective energy are lower for orthogonal beams than for forward beams, and the differences are more pronounced for targets of lower atomic number. The effective energy of a spectrum produced by carbon dropped by a factor of 10 from 1535 keV in the forward direction to 151 keV in the orthogonal direction, while for aluminum the effective energy dropped by 77% to 425 keV, and for copper by 37% to 1107 keV. The image contrast of films exposed with orthogonal beams was qualitatively determined to be superior to that obtained using the forward megavoltage beams. Using their relatively low effective energy, orthogonal bremsstrahlung beams produced by megavoltage electrons striking low atomic number targets yield images with a higher contrast than do forward bremsstrahlung beams.
Sci‐Fri AM General‐09: Pseudo‐Monoenergetic X‐Ray Diffraction Imaging using Balanced Filters
Authors: Beath S , Lazarev S , Cunningham I
Published: July 2006

In the treatment of kidney stones, knowing stone composition has been established as an important aid to the understanding of stone formation and in preventing recurrences, particularly the composition of the initial “core” of the stone. Traditionally, stone composition has come from laboratory techniques such as infrared spectroscopy and x‐ray diffraction. These methods require taking multiple samples of excised stone fragments and powdering them — losing structural information in the process. Furthermore, since stone composition is rarely homogenous, samples must be drawn from enough materially distinct regions of the stone or some components may not be identified. Low‐angle coherent scatter (CS) at diagnostic energies provides tissue‐composition information that can distinguish between different biological materials. Previously, our lab has developed a system to capture these CS patterns and to match them to known patterns of pure component materials. A drawback of the system is that it uses a polyenergetic x‐ray source. Since the CS angular distribution is energy‐dependent, an angular blurring of the measured cross section occurs, impairing the system's ability to accurately identify composition. To overcome this drawback, the spectral width of the x‐rays must be reduced. One way to achieve this uses two filters to create two CS patterns, which are then subtracted. If the filters are chosen with similar atomic numbers, the subtracted scatter pattern will be formed primarily by x‐rays in a narrow energy range. In this article we present an application of this “balanced filter technique” that will improve the scatter pattern uniqueness of kidney stone components.
Sci‐Fri AM General‐10: An Apparent Threshold Dose Effect in Radiochromic Gel Dosimeters
Authors: Babic S , Battista J , Jordan K
Published: July 2006

Purpose: To identify the chemical and or physical cause of a threshold dose in the low dose response of FXG gel dosimeters.

Methods: Gels were prepared by mixing stock solutions of ferrous‐ammonium‐sulphate and different chemical supplies of xylenol‐orange (XO) together with sulfuric acid into a solution of gelatin and distilled water. Concentrations of ferrous‐ammonium‐sulphate, XO and sulfuric acid were varied to identify one of these chemicals as a source of impurities potentially causing the threshold dose effect. Samples in 1 or 10cm acrylic cuvettes were irradiated to doses between 0–5Gy. Optical transmissions were measured through the samples and referenced to water at 589 and 543nm, respectively, using an absorption spectrophotometer. This procedure was repeated for gelatin‐free FX solutions and with gel containing varying concentrations of ferric‐ammonium‐sulphate.

Results: The threshold dose decreased to 0.20±0.05 Gy using reagent grade XO. There was no correlation between threshold dose and varying concentrations of ferrous and sulphuric acid although decreasing the XO concentration from 0.05 to 0.025mM lowered the threshold dose by a factor of two. Gelatin‐free FX solutions showed a threshold dose. Using a ferric concentration of 7.5uM decreased the threshold dose to 0.04±0.03 Gy. The threshold dose effect was not present at 543nm.

Conclusions: Chemical impurities are not responsible for the threshold dose. The “apparent” threshold dose is caused by the production of different Fe(III)i:XOj species (each with their own respective spectral absorptivity). These species are formed at different dose levels and sensitivity to detecting these species requires optimization of the readout wavelength.
Sci‐Fri PM Imaging‐01: Comparison of POCS and cTERA Image Reconstruction Algorithms Applied to 3D Sparsely Sampled k‐Space Data
Authors: Peng H , Sabati M , Lauzon M , Frayne R
Published: July 2006

Real‐time 3D magnetic resonance (MR) imaging sometimes focus on rapid data acquisition by full sampling the central zone of phase‐encoding plane while sparse sampling its periphery, which results in the formation of sparsely sampled MR raw data. This research compares the performance of image reconstruction from sparsely sampled MR data by the often‐used zero filling (ZF) algorithm, and by two new methods, i.e., projection‐onto‐convex sets (POCS) and constrained transient error reconstruction approach (cTERA) algorithms. It is found that both the POCS and cTERA algorithms reconstruct high‐quality images that greatly improve the depiction of high‐frequency‐containing structures compared to ZF. However, POCS and cTERA take significantly increased computational times. Due to their intrinsic complexities compared to conventional Fourier transform and ZF reconstruction, POCS and cTERA algorithms are currently not implemented on commercial clinical MR scanners. It is also demonstrated that for a given scan time, it is possible to find an optimal specific sparse sampling strategies by both POCS and cTERA. Under pseudo optimal conditions, the corresponding POCS and cTERA images demonstrated better high‐resolution image quality compared to other, less optimal, sampling strategies. Therefore, it is desirable to acquire some high‐frequency data, as opposed to spending time only collecting an enlarged central region.
Sci‐Fri PM Imaging‐02: Experimental evaluation of Otsu's thresholding technique for air‐volume measurements
Authors: Madani A , Cunningham I
Published: July 2006

Estimates of lung air volumes are often made in the clinical assessment of respiratory diseases using high‐resolution computed tomography (HRCT). Most algorithms are based on a thresholding of CT Hounsfield unit (HU) values using the “Otsu” method. This algorithm was developed for character recognition tasks in digital image processing chooses an algorithm that separates air from soft tissue by maximizing the ratio of intra‐class to inter‐class variances in voxel HU values. While the Otsu algorithm is widely used, it has not been experimentally validated. We tested the Otsu algorithm in a lung phantom containing solid spheres of known diameter using both HRCT and small‐animal uCT images. We found that air volumes could be determined using HRCT with an inaccuracy of less than 10% when sphere diameters were greater than 3 mm. Spheres of 2 and 1‐mm diameter gave errors of 38% and 75% respectively. It is concluded that thresholding of HRCT using the Otsu method can be accurate in regions containing air spaces larger than 3 mm, but not in regions containing alveoli as they are typically much less than a mm in diameter.
Sci‐Fri PM Imaging‐10: LabPETtm: A Second‐Generation APD‐Based Digital Scanner for High‐Resolution Small Animal PET Imaging
Authors: Lecomte R , deKemp RA , Klein R , Cadorette J , Lepage MD , Robert G , Selivanov V , Bélanger F , Semmaoui H , Tétrault MA , Viscogliosi N , Bergeron M , Lemieux F , Lemonde MA , Fontaine R
Published: July 2006

LabPET™ is a novel APD‐based PET scanner with quasi‐individual crystal readout and highly parallel digital architecture for high‐performance in vivo molecular imaging of small animals. It consists of 16 rings, 16.2 cm in diameter, each formed by 192 2×2×(9.9–11.3) mm3 scintillators assembled in LYSO/LGSO phoswich pairs read out by an avalanche photodiode (APD). The field of view extends up to 110 mm in diameter by 37.5 mm axially. The dual‐crystal readout scheme avoids resolution degradation due to light‐ or charge‐sharing and enables very high singles count rates with low dead time. Advanced parallel algorithms for signal processing and analysis implemented in high‐performance programmable devices perform crystal identification, energy discrimination and time stamping of individual pixels in real‐time. Virtually error‐free crystal identification is achieved using an auto‐regressive moving average method. Coincidence events are sorted in real‐time and recorded in list‐mode, together with scanner status information and animal physiological data. The intrinsic spatial resolution (both radial and axial) at the FOV center is 1.2 mm FWHM (2.3 mm FWTM). The 1.2‐mm diameter hot rods can be clearly resolved in images of a resolution phantom. Preliminary time resolutions of 2.5 and 3.9 ns FWHM were obtained respectively for LYSO‐LYSO and LGSO‐LGSO coincidences using an auto‐regressive least‐mean square timing algorithm. The system is implemented with ancillary devices (injectors, life‐sign monitors, blood counter…) controlled through a centralized user‐interface, offering a fully integrated solution for performing demanding molecular imaging investigations with increased throughput in a busy research environment.
Sci‐Sat AM (1) General‐03: IMRT prostate planning: a graphical rectal NTCP determination
Authors: Grigorov G , Chow J , Grigorov L , Jiang R , Barnett R
Published: July 2006

Including the NTCP in the objective function of the inverse IMRT plan optimization would make the planning more effective in the prediction of the post‐radiation effects. However, doing so would lengthen the total planning time. The purpose of this work is to establish a method for rectal NTCP determination, independent of the DVH, as a means of improving the treatment planning efficiency. In this study, IMRT plans of ten randomly selected prostate patients are performed using Pinnacle3 V 6.2b planning system. The DVH control points and prescriptions for contouring of the PTVs and OARs were adapted from the prescriptions of the Radiation Therapy Oncology Group protocol P‐0126. PTVs with margins in the range of 2 to 10 mm and prescribed dose ranging from 70 to 82 Gy were employed in our study. This paper presents a new model for determination of the rectal NTCP (RNTCP). The method uses a special function, named GVN (from Gy, Volume, NTCP). It describes the RNTCP if a volume of 1 cm3 of the intersection between the PTV and rectum is irradiated uniformly by a dose of 1 Gy. The function was “geometrically” normalized using a prostate‐prostate‐ratio (PPR) of the patients' prostates. Also, a correction of the RNTCP for different prescribed doses was used. The argument of the normalized function is the rectum intersection, and parameters are the prescribed dose, prostate volume, PTV margin and PPR.
Sci‐Sat AM (1) General‐05: Measurement of Coherent Scattering Form Factors using Polychromatic X‐Ray Sources and Imaging Detectors
Authors: King B , Johns P
Published: July 2006

A method of measuring coherent scattering form factors using polychromatic x‐ray spectra and an energy insensitive imaging detector is developed. We show that the coherent scattering process can be formulated as a matrix equation and that the equation can be inverted to recover the coherent scattering form factor. We show that the model reproduces the known behaviour in the case of a monochromatic spectrum and demonstrate the extraction of the form factor via numerical simulations of the small angle scatter image of a small sample of water and two different x‐ray spectra: a rectangular spectrum in the range 25 – 45 keV and a realistic 50 kVp spectrum from the tungsten anode of a clinical x‐ray tube. Good agreement between the extracted and original form factor is obtained, although the quality of the extracted form factor can be strongly affected by the shape of the incident spectrum and the presence of noise in the scatter image. Further study is required to fully understand the physical and numerical limitations. The method could allow accurate measurements of coherent scattering form factors using clinical hardware.
Sci‐Sat AM (1) General‐07: Water equivalent dosimeter array for small fields external beam radiotherapy
Authors: Archambault L , Frelin A‐M , Gingras L , Beddar A , Beaulieu L
Published: July 2006

Scintillation dosimeters consisting of a scintillating fiber coupled to an optical fiber and read with a CCD camera have shown accurate dose measurement in external beam radiotherapy. This work presents the next step, which is to investigate the development of a multi‐channel dosimeter array in conjunction with a CCD camera for dose measurement that includes small fields. The light collection of the CCD camera was studied to evaluate the number of detectors that can be read simultaneously. We also looked at possible sources of dose perturbation with a single‐fiber detector surrounded by other optical fibers. We then constructed a prototype array with 10 detectors and compared with measurements taken with small ion chambers. No dose perturbations were seen when a plastic optical fiber was used to transmit the scintillation light to the CCD. Depth dose curves measured in water with a scintillation dosimeter with up to 75 plastic optical fibers in the beam showed no discrepancy to within 0.3% when compared to the same curve taken with an ion chamber and without the plastic fibers. Agreement within 0.6% was seen for output factor measured with the scintillator and the A16 Exradin chamber for fields of 1×1 cm2 and 5×0.5 cm2. The ten‐fiber prototype allowed precise evaluation of profile and depth dose curves in a single irradiation. This work has shown that use of a multi‐channel scintillation dosimeter is feasible. The prototype of 10 detectors produced excellent results and could be extended up to 3000 detectors in the near future.
Sci‐Sat AM (2) Therapy‐03: Characterization of Intermediate Energy X‐Ray Photons (0.2–1.0 MeV) for stereotactic radiosurgery: experimental demonstration of reduced radiological penumbra
Authors: Keller B , O'Malley L , Beachey D , Presutti J , Pignol JP
Published: July 2006

Introduction: Stereotactic radiosurgery is used to treat intracranial lesions with a high degree of accuracy. At the present time, x‐ray energies at or above Co‐60 gamma rays are used. We hypothesize that intermediate energy x‐ray photons (IEP's), combined with small field sizes, produce a reduced radiological penumbra leading to a sharper dose gradient. The purpose of this work is three‐fold: 1.) to produce IEP's using a medical linear accelerator 2.) to characterize the x‐ray energy 3.) to demonstrate reduced radiological penumbra for IEP's compared to 6MV x‐rays.

Materials & Methods: A Siemens linear accelerator was modified to produce IEP's. PDD versus depth measurements were done in solid water using a Markus parallel plate ionization chamber (PTW Freiburg) at SSD=100cm for a 2×2cm2 field size. Monte Carlo computer simulations were done using MCNP‐4C. A penumbra measurement device was constructed to examine radiological penumbra for various photon energies, field sizes and depths. Film (Gafchromic EBT) was used to record field edge profiles. These films were scanned using a digital microscope (spatial resolution of 1.87 microns/pixel). Film irradiations were done using SSD=100cm, depth= 2cm, FS=1.1cm2.

Results: For the IEP's, PDD values were 55.4%(surface), 62.6%(5cm), and 34.7%(10cm). Monte Carlo simulations suggest a nominal x‐ray energy of 800kV. The 80%–20% penumbra widths were 2.10mm (6MV) and 0.345mm (IEP's).

Conclusions: A novel intermediate energy x‐ray beam (800kV) has been produced using a linear accelerator. There is more than a 5‐fold reduction in radiological penumbra for the IEP's versus 6MV x‐rays for the small field size examined.
Sci‐Sat AM (2) Therapy‐07: Feasibility of 3D ultrasound guided brachytherapy for lung cancer using a porcine lung tumour model
Authors: Lewis C , Bickhram M , Yu E , Wei Z , Hornblower V , Malthaner R
Published: July 2006

The standard treatment of localized early stage non‐small cell lung cancer is surgical resection. However, most patients are not candidates for surgery due to poor lung function and comorbidities. Minimally invasive interstitial brachytherapy may be an option for these patients. An in vivo dosimetry test box was constructed to simulate the thoracic cavity and allow 3D ultrasound imaging of the brachytherapy needles. The box stabilizes the ultrasound probe and facilitates insertion of brachytherapy needles parallel to the probe axis. Seeds were implanted, targeted at the centre of a 1.5 cm agar sphere in 6% gelatin and then imaged using the 3D ultrasound and CT scans. The dosimetric impact of seed location was examined using Theraplan Plus. The DVH (dose volume histogram) was calculated assuming an seed activity that would cover the sphere with an arbitrary D90 of 25Gy if the seed was located at the centre of the sphere. DVH D90 values for the actual implanted seed positions will be presented comparing CT to ultrasound. This procedure was repeated in an ex vivo lung tumour model consisting of agar spheres implanted into excised collapsed porcine lungs. Initial 3D ultrasound measurements were done with a probe designed for prostate brachytherapy. However, the measurements will be repeated with a smaller diameter thoracoscopic ultrasound probe that will be used clinically. This pilot work demonstrates the feasibility of using 3D ultrasound to target seed insertion and calculate dosimetry in a brachytherapy lung tumour model.
NUMERICAL METHODS FOR DIFFERENTIAL GAMES BASED ON PARTIAL DIFFERENTIAL EQUATIONS
Authors: FALCONE M.
Published: July 2006

In this paper we present some numerical methods for the solution of two-persons zero-sum deterministic differential games. The methods are based on the dynamic programming approach. We first solve the Isaacs equation associated to the game to get an approximate value function and then we use it to reconstruct approximate optimal feedback controls and optimal trajectories. The approximation schemes also have an interesting control interpretation since the time-discrete scheme stems from a dynamic programming principle for the associated discrete time dynamical system. The general framework for convergence results to the value function is the theory of viscosity solutions. Numerical experiments are presented solving some classical pursuit-evasion games.
COMPUTING EQUILIBRIA IN STOCHASTIC GAMES OF INTERGENERATIONAL EQUITY
Authors: HAURIE ALAIN B. , MORESINO FRANCESCO
Published: July 2006

In this paper we further explore the properties and computational methods of intergenerational equilibrium solutions for a class of multi-generation stochastic games that are inspired by the intergenerational equity issues typically found in cost-benefit analysis for climate change policies. We first extend previous results by showing that discounting over time and over generations yields to an intergenerational equilibrium which is equivalent to the use of a lower discount rate. We then propose a model that encompasses the different formulations proposed before to represent intergenerational equilibria in the presence of selfishness. We propose a numerical method to compute these equilibria and we test it on an adaptation of the DICE94 model proposed by Nordhaus to do cost-benefit analysis of climate policies.
DYNAMIC GAMES WITH COALITIONAL STRUCTURES
Authors: PETROSJAN LEON , MAMKINA SVETLANA
Published: July 2006

The paper explores the properties of multistage games with perfect information, in which (unlike the classic Kuhnian definition) the conditional coalition partition at any vertex is determined by a chance move and remains unchanged until the random process repeats at the next vertex. A new value for such a game is proposed in terms of a PMS-vector. It is computed by backward induction using conditional partition and transition in the vertices. An illustrative example is provided.
SOLUTION MECHANISMS FOR COOPERATIVE STOCHASTIC DIFFERENTIAL GAMES
Authors: YEUNG DAVID W. K.
Published: July 2006

Cooperative stochastic differential games constitute a highly complex form of decision making under uncertainty. In particular, interactions between strategic behaviors, dynamic evolution, stochastic elements and solution agreement have to be considered simultaneously. This complexity leads to great difficulties in the derivation of dynamically stable solutions. Despite urgent calls for cooperation in the global economy, the lack of formal analyses has precluded rigorous analysis of this problem. In this paper, mechanisms for the derivation of dynamically stable solutions to cooperative stochastic differential games are presented. Games with transferable payoffs and those with nontransferable payoffs are considered. Numerical illustrations are also provided.
No effect of menstrual cycle phase on basal very-low-density lipoprotein triglyceride and apolipoprotein B-100 kinetics
Authors: Magkos Faidon , Patterson Bruce W. , Mittendorfer Bettina
Published: July 2006

Dyslipidemia, manifested by increased plasma triglyceride (TG), increased total and LDL-cholesterol concentrations and decreased HDL-cholesterol concentration, is an important risk factor for cardiovascular disease. Premenopausal women have a less atherogenic plasma lipid profile and a lower risk of cardiovascular disease than men, but this female advantage disappears after menopause. This suggests that female sex steroids affect lipoprotein metabolism. The impact of variations in the availability of ovarian hormones during the menstrual cycle on lipoprotein metabolism is not known. We therefore investigated whether very-low-density lipoprotein (VLDL)-TG and VLDL-apolipoprotein B-100 (apoB-100) kinetics are different during the follicular (FP) and luteal phases (LP) of the menstrual cycle. We studied seven healthy, premenopausal women (age 27 ± 2 yr, BMI 25 ± 2 kg/m2) once during FP and once during LP. We measured VLDL-TG, VLDL-apoB-100, and plasma free fatty acid (FFA) kinetics by using stable isotope-labeled tracers, VLDL subclass profile by nuclear magnetic resonance spectroscopy, whole body fat oxidation by indirect calorimetry, and the plasma concentrations of lipoprotein lipase (LPL) and hepatic lipase (HL) by ELISA. VLDL-TG and VLDL-apoB-100 concentrations in plasma, VLDL-TG and VLDL-apoB-100 secretion rates and mean residence times, VLDL subclass distribution, FFA concentration and rate of appearance in plasma, whole body substrate oxidation, and LPL and HL concentrations in plasma were not different during the FP and the LP. We conclude that VLDL-TG and VLDL-apoB-100 metabolism is not affected by menstrual cycle phase.
Gene deletion reveals roles for annexin A1 in the regulation of lipolysis and IL-6 release in epididymal adipose tissue
Authors: Warne James P. , John Christopher D. , Christian Helen C. , Morris John F. , Flower Roderick J. , Sugden David , Solito Egle , Gillies Glenda E. , Buckingham Julia C.
Published: July 2006

In this study, epididymal adipose tissue from male annexin 1 (ANXA1)-null and wild-type control mice were used to explore the potential role of ANXA1 in adipocyte biology. ANXA1 was detected by Western blot analysis in wild-type tissue and localized predominantly to the stromal-vascular compartment. Epididymal fat pad mass was reduced by ANXA1 gene deletion, but adipocyte size was unchanged, suggesting that ANXA1 is required for the maintenance of adipocyte and/or preadipocyte cell number. Epididymal tissue from wild-type mice responded in vitro to noradrenaline and isoprenaline with increased glycerol release, reduced IL-6 release, and increased cAMP accumulation. Qualitatively similar but significantly attenuated responses to the catecholamines were observed in tissue from ANXA1-null mice, an effect that was not associated with changes in β-adrenoceptor mRNA expression. Lipopolysaccharide (LPS) also stimulated lipolysis in vitro, but its effects were muted by ANXA1 gene deletion. By contrast, LPS failed to influence IL-6 release from wild-type tissue but stimulated the release of the cytokine from tissue from ANXA1-null mice. ANXA1 gene deletion did not affect glucocorticoid receptor expression or the ability of dexamethasone to suppress catecholamine-induced lipolysis. It did, however, augment IL-6 expression and modify the inhibitory effects of glucocorticoids on IL-6 release. Collectively, these studies suggest that ANXA1 supports aspects of adipose tissue mass and alters the sensitivity of epididymal adipose tissue to catecholamines, glucocorticoids, and LPS, thereby modulating lipolysis and IL-6 release.
Pitx3 Deficiency in Mice Affects Cholinergic Modulation of GABAergic Synapses in the Nucleus Accumbens
Authors: de Rover Mischa , Lodder Johannes C. , Smidt Marten P. , Brussaard Arjen B.
Published: July 2006

We investigated to what extent Pitx3 deficiency, causing hyperdopaminergic transmission in the nucleus accumbens microcircuitry, may lead to developmental changes. First, spontaneous firing activity of cholinergic interneurons in the nucleus accumbens was recorded in vitro. Firing patterns in the Pitx3-deficient mice were more variable and intrinsically different from those observed in wild-type mice. Next, to test whether the irregular firing patterns observed in mutant mice affected the endogenous nicotinic modulation of the GABAergic input of medium spiny neurons, we recorded spontaneous GABAergic inputs to these cells before and after the application of the nicotinic receptor blocker mecamylamine. Effects of mecamylamine were found in slices of either genotype, but in a rather inconsistent manner. Possibly this was attributable to heterogeneity in firing of nearby cholinergic interneurons. Thus paired recordings of cholinergic interneurons and medium spiny neurons were performed to more precisely control the experimental conditions of the cholinergic modulation of GABAergic synaptic transmission. We found that controlling action potential firing in cholinergic neurons leads to a conditional increase in GABAergic input frequency in wild-type mice but not in Pitx3-deficient mice. We conclude that Pitx3-deficient mice have neural adaptations at the level of the nucleus accumbens microcircuitry that in turn may have behavioral consequences. It is discussed to what extent dopamine release in the nucleus accumbens may be a long-term gating mechanism leading to alterations in cholinergic transmission in the nucleus accumbens, in line with previously reported neural adaptations found as consequences of repeated drug treatment in rodents.
H-Reflex Operant Conditioning in Mice
Authors: Carp Jonathan S. , Tennissen Ann M. , Chen Xiang Yang , Wolpaw Jonathan R.
Published: July 2006

Rats, monkeys, and humans can alter the size of their spinal stretch reflex and its electrically induced analog, the H-reflex (HR), when exposed to an operant conditioning paradigm. Because this conditioning induces plasticity in the spinal cord, it offers a unique opportunity to identify the neuronal sites and mechanisms that underlie a well-defined change in a simple behavior. To facilitate these studies, we developed an HR operant conditioning protocol in mice, which are better suited to genetic manipulation and electrophysiological spinal cord study in vitro than rats or primates. Eleven mice under deep surgical anesthesia were implanted with tibial nerve stimulating electrodes and soleus and gastrocnemius intramuscular electrodes for recording ongoing and stimulus-evoked EMG activity. During the 24-h/day computer-controlled experiment, mice received a liquid reward for either increasing (up-conditioning) or decreasing (down-conditioning) HR amplitude while maintaining target levels of ongoing EMG and directly evoked EMG (M-responses). After 3–7 wk of conditioning, the HR amplitude was 133 ± 7% (SE) of control for up-conditioning and 71 ± 8% of control for down-conditioning. HR conditioning was successful (i.e., ≥20% change in HR amplitude in the appropriate direction) in five of six up-conditioned animals (mean final HR amplitude = 139 ± 5% of control HR for successful mice) and in four of five down-conditioned animals (mean final HR amplitude = 63 ± 8% of control HR for successful mice). These effects were not attributable to differences in the net level of motoneuron pool excitation, stimulation strength, or distribution of HR trials throughout the day. Thus mice exhibit HR operant conditioning comparable with that observed in rats and monkeys.
Unexpected diversity displayed in cDNAs expressed by the immune cells of the purple sea urchin,Strongylocentrotus purpuratus
Authors: Terwilliger David P. , Buckley Katherine M. , Mehta Dhruti , Moorjani Priya G. , Smith L.Courtney
Published: July 2006

We recently identified a unique family of transcripts, the 185/333 family, that comprise ∼60% of the mRNAs induced by coelomocytes from the purple sea urchin in response to immunological challenge from lipopolysaccharide. An analysis of 81 full-length cDNAs revealed 67 unique nucleotide sequences encoding 64 different proteins. Diversity of the transcripts was based on 25 sequence blocks, or “elements,” which resulted in 22 different element patterns based on their presence or absence. Furthermore, there was a high level of nucleotide variation within elements, including single nucleotide polymorphisms and insertions/deletions, both of which resulted in amino acid sequence variability. The deduced 185/333 proteins contained an NH2-terminal leader, a glycine-rich region with an RGD motif, a histidine-rich region, and a COOH-terminal region. Two 185/333 genes, identified in the partially assembled Strongylocentrotus purpuratus genome, have two exons. The first encoded the leader, and the second encoded the remainder of the predicted protein. Estimates from quantitative PCR indicated that there were ∼100 alleles in the diploid genome. These results suggested that the purple sea urchin may have mechanisms for generating high levels of diversity in response to immunological challenge that have not been considered previously.
A second expressed kininogen gene in mice
Authors: Shesely Edward G. , Hu Chun-Bo , Alhenc-Gelas François , Meneton Pierre , Carretero Oscar A.
Published: July 2006

We isolated PCR, RNA ligase-mediated rapid amplification of cDNA ends (RLM-RACE-PCR)-, and RT-PCR-generated clones from mouse kininogen family transcripts. DNA sequencing indicated that the clones were from two distinct genes. One set (K1) is from the previously reported mouse kininogen gene. The second set (K2) has an open reading frame, is 93% identical to K1 in the overlapping nucleotide sequence, and, unlike T-kininogens in the rat, encodes a bradykinin motif identical to K1. We discovered that K2 exists with two different 5′ ends. We used RT-PCR to determine the distribution and relative abundance of K1 and K2 mRNA in mouse tissues. K2 is transcribed and K1 and K2 are generally both expressed in the same tissues; however, they differ in their regulation of the alternative splicing event that yields either low-molecular-weight kininogen (LMWK) or high-molecular-weight kininogen (HMWK). For example, in the liver K1 is expressed as both HMWK and LMWK, whereas K2 is only expressed as LMWK. Conversely, in the kidney K2 is strongly expressed as both HMWK and LMWK, whereas K1 is not expressed as HMWK and expressed only very weakly as LMWK.
Stereotactic Radiosurgery as a Salvage Treatment for Recurrent Epipharyngeal Carcinoma
Authors: Oda Kyota , Mori Yoshimasa , Kobayashi Tatsuya , Kida Yoshihisa , Yokoi Hisashi , Shibamoto Yuta , Yoshida Jun
Published: July 2006

Fourteen patients with recurrent epipharyngeal carcinoma (EPC) were treated by gamma knife stereotactic radiosurgery. The tumor volume ranged from 0.3 to 80 ml (median 18.9 ml). Treatment was done with a tumor margin dose of 10–27 Gy (median 15 Gy). The median follow-up period was 15 months (range 2–47 months). Ten patients were alive and 4 were dead at the end of the follow-up period. In 6 patients (43%), the tumor disappeared or decreased in size until the end of the follow-up period. In 2 (14%), the tumor remained unchanged in size. In 6 (43%), the tumor showed regression initially but was enlarged later. A second radiosurgery was performed in 4 of those 6 cases and the tumor decreased in size again in 3 of them. Thus, the overall control rate of local tumor was 79% (11/14). In selected patients with recurrent EPC, stereotactic radiosurgery can be considered as a salvage treatment producing local control.
Application Accuracy of Automatic Registration in Frameless Stereotaxy
Authors: Rachinger Jens , von Keller Boris , Ganslandt Oliver , Fahlbusch Rudolf , Nimsky Christopher
Published: July 2006

Objective: We compared the application accuracy of an infrared-based neuronavigation system when used with a novel automatic registration with its application accuracy when standard fiducial-based registration is performed. Methods: The automatic referencing tool is based on markers that are integrated in the headrest holder we routinely use in our intraoperative magnetic resonance imaging (MRI) setting and can be detected by the navigation software automatically. For navigation targeting we used a Plexiglas phantom with 32 notched rods of different heights. The phantom was fixed in the head holder and multiple optimized gradient echo slices containing the clamp-integrated markers were acquired. After that we measured a T1 MPRAGE sequence with a slice thickness of 1.0 mm for navigation. The deepest points of the surface of the rods were defined as target points in image space. In three measurement series we referenced the phantom once with 4, once with 7 fiducials and twice automatically. In one series we performed only one automatic registration. The localization error was measured 3 times per rod and registration. Results: The median localization errors for standard registration with 7 fiducials were between 1.2 and 3.05 mm. With 4 fiducials, medians were in the range from 1.87 to 2.21 mm. For the automatic registration we obtained median localization errors between 0.88 and 2.13 mm. In 6 of the 8 samples that were compared the automatic registration showed an application accuracy that was highly significantly better (p < 0.001 in most cases) than that of fiducial-based standard registration. Conclusion: The application accuracy found for automatic referencing is at least not worse than that for standard registration no matter whether 4 or 7 fiducial markers were used. Therefore, its use in the operating room is feasible. In combination with intraoperative MRI it may become a favorable alternative to standard fiducial-based registration especially when an intraoperative update of navigation data is necessary.
Optical Measurements during Experimental Stereotactic Radiofrequency Lesioning
Authors: Antonsson Johan , Eriksson Ola , Lundberg Peter , Wårdell Karin
Published: July 2006

The aim of this study was to evaluate in vivo a laser Doppler measurement system in porcine brain tissue during thermal lesioning. A 2-mm monopolar radiofrequency lesioning electrode was equipped with optical fibers in order to monitor the lesioning procedure. Laser Doppler and backscattered light intensity signals were measured along the electrode trajectory and during bilateral lesioning in the central gray (70, 80 and 90°C, n = 14). The time course of the coagulation process could be followed by optical recordings. Two separate groups of tissue were identified from the intensity signals. The changes in the perfusion levels in both groups displayed significant changes (p < 0.05, n = 48) at all temperature settings, while backscattered light intensity was significant for only one group at the different temperatures (p < 0.05, n = 39). These results indicate that optical measurements correlate with lesion development in vivo. The study also indicates that it is possible to follow the lesioning process intra-operatively.
Cystadenomas with Ovarian Stroma in Liver and Pancreas: An Evolving Concept
Authors: Erdogan D. , Lamers W.H. , Offerhaus G.J.A. , Busch O.R.C. , Gouma D.J. , van Gulik T.M.
Published: July 2006

Background: Mucinous cystic neoplasms with ovarian stroma (OS) are rare cystic neoplasms in the liver and pancreas. The aim was to investigate whether OS in mucinous cystadenomas can originate from gonadal epithelium during early embryonic development. Patients and Methods: Pathology specimens of patients with mucinous cystadenomas were reviewed for OS. In human embryos, morphology of the peritoneal epithelium and the position of the gonads in relation to the embryonic liver, pancreas and spleen were examined. Results: From 1994 to 2004, 22 female patients presented with mucinous neoplasms of the liver or pancreas, including 19 cystadenomas and 3 cystadenocarcinomas. Mean age of the patients with cystadenoma in the liver was 44.8 years and with cystademona in the pancreas 41.2 years. OS was present in all mucinous cystadenomas, including the cystadenocarcinomas. In human embryos, preceding their ‘descent’, the gonads are situated directly under the diaphragm, dorsal to the liver, the tail of the pancreas and the spleen, but separated from these organs by the peritoneal cavity. In contrast to the peritoneal epithelium elsewhere, the cells covering the gonads show an activated morphology. Conclusion: OS in mucinous cystadenomas of the liver and pancreas suggest a common origin in epithelial cells that cover the embryonic gonads in early fetal life.
Diagnostic Tests Based on Human Basophils: Potentials, Pitfalls and Perspectives
Authors: Kleine-Tebbe Jörg , Erdmann Stephan , Knol Edward F. , MacGlashan Jr. Donald W. , Poulsen Lars K. , Gibbs Bernhard F.
Published: July 2006

Human basophils are important tools for studying immediate-type hypersensitivity reactions since they release a variety of mediators (e.g., histamine, leukotriene C4, IL-4 and IL-13) following allergen triggering. Several diagnostic tools have been introduced that measure either leukotriene production or the upregulation of surface markers (CD63 and CD203c) from these cells after antigen stimulation. However, a broad variability in basophil activity exists between different basophil donors and different antigens within one donor. This manifests itself in terms of their reactivity (maximum secretory response), based on the intracellular signaling of the basophils studied, and in terms of their sensitivity. The latter is governed by the number of IgE receptors per basophil, the ratio of antigen-specific IgE to total IgE, and by the number of cell surface antigen-specific IgE molecules for half-maximal responses, termed ‘intrinsic sensitivity’. These variables give rise to shifts in the dose-response curves which, in a diagnostic setting where only a single antigen concentration is employed, may produce false-negative data. Thus, in order to meaningfully utilize the current basophil activation tests for diagnostic purposes, each allergen should be pre-evaluated separately in order to determine a suitable stimulation range. Additionally, anti-IgE or anti-FcΕRIα antibodies should serve as positive controls, bearing in mind that 10–20% of basophil donors are not responsive to IgE-mediated stimulation. Diagnostic studies using CD63 or CD203c in hymenoptera, food and drug allergy are critically discussed. Basophil-based tests are indicated for allergy testing in selected cases but should only be performed by experienced laboratories.
Some Pregnancy-Related Effects of Artemether in Laboratory Animals
Authors: Ejiofor Janet I. , Kwanashie Helen O. , Anuka Joseph A.
Published: July 2006

Artemether, highly effective in multi-drug-resistant malaria is not routinely available for use in pregnancy due to the lack of adequate research data in animals and man. This study was therefore aimed at investigating some pregnancy-related effects of artemether. Artemether (1.5, 7.5 and 15 mg/kg i.p. daily for 7 days) did not produce changes in rat oestrous cycle. The drug did not prevent or prolong the rate of conception or parturition, cause pre-term delivery and affect litter size. Birth weight and growth rate of pups from artemether-pretreated dams were within the normal range. Artemether (48–480 µg/ml) had no agonist effect on the isolated uterine smooth muscles of both non-pregnant and pregnant rats and guinea pigs. However, the drug (24– 240 µg/ml) reduced oxytocin-induced contraction of uterine tissues concentration-dependently, particularly in pregnant uteri.
A Pilot Study on Chemospecific Duodenal Visceral Sensitivity in Inflammatory Bowel Disease in Remission
Authors: Minderhoud Itta M. , Smout André J. , Oldenburg Bas , Samsom Melvin
Published: July 2006

Background: Patients with inflammatory bowel disease (IBD) in remission frequently experience symptoms resembling irritable bowel syndrome (IBS). In IBS altered motility and visceral sensitivity are found throughout the whole gastrointestinal tract. We aimed to study chemospecific antroduodenal sensitivity in IBD patients. Methods: Antroduodenal manometry was performed in 10 IBD patients in remission and 13 controls. Small volumes of nutrients and acid were administered intraduodenally. Motility variables and sensation scores were compared before and after each infusion. Results: Acid and lipid infusion decreased the number of antral pressure waves in both groups (p < 0.05). After acid infusion the number of duodenal pressure waves in the sideholes just distal to the infusion port increased in IBD patients compared to the controls (p < 0.05). Lipid infusion increased the number of duodenal propagated pressure waves in both groups, but in controls they were also increased over longer distances (p < 0.005). None of the infusions significantly affected the sensation scores. Conclusion: Subtle alterations in chemospecific responses to lipids and acid in IBD patients in remission were observed, affecting duodenal motor activity but not duodenal perception. These changes are indicative of changes at the chemoreceptor level in the duodenal wall in this patient group.
Prevalence of Ineffective Esophageal Motility and Its Relevance to Symptoms and Esophageal Acid Exposure in Korean Patients Referred for Foregut Symptoms
Authors: Lee Kwang Jae , Kim Jin Hong , Cho Sung Won
Published: July 2006

Background/Aims: The prevalence and clinical significance of ineffective esophageal motility (IEM) in a population with low prevalence of gastroesophageal reflux disease are not known. Our aim was to investigate the prevalence and its relevance to symptoms and esophageal acid exposure in Korean patients referred for foregut symptoms. Methods: A total of 112 consecutive patients who underwent esophageal manometry, 24-hour esophageal pH monitoring and endoscopy for foregut symptoms were analyzed. IEM was defined as >20% of wet swallows with amplitudes of <30 mm Hg or lack of peristalsis. Results: IEM and abnormal acid exposure were observed in respectively 29 and 19% of all subjects. The prevalence of individual symptoms did not differ between IEM and non-IEM groups. Hypotensive lower esophageal sphincter (LES) was significantly more prevalent in IEM patients. The prevalence of abnormal acid exposure in IEM and non-IEM groups was comparable. The prevalence of IEM was similar between patients with and without abnormal acid exposure. Erosive reflux esophagitis was significantly more prevalent in IEM patients compared with non-IEM patients. Conclusion: IEM is not a significant marker for a specific symptom or abnormal acid exposure. However, the presence of IEM is associated with a higher prevalence of hypotensive LES and erosive reflux esophagitis.
A Meta-Analysis: Comparison of Esomeprazole and Other Proton Pump Inhibitors in Eradicating Helicobacter pylori
Authors: Wang Xia , Fang Jing-Yuan , Lu Rong , Sun Dan-Feng
Published: July 2006

Background: To assess effects of esomeprazole-based therapies and others (PPIs) on Helicobacter pylori eradication when co-administered with antibiotics. Goals: Using the terms ‘H. pylori eradication’ and ‘esomeprazole’, we searched Medline, Embase, and the Cochrane Library (2000–2005) and conducted a manual search of related Chinese journals to identify randomized controlled trials (RCTs) that compared the treatment effects of esomeprazole and other PPI therapies in patients with H. pylori infection. Results: Of the 75 articles screened, 11 RCTs including 2,159 subjects were included in the meta-analysis. The mean H. pylori eradication rates (intention-to-treat, ITT) with esomeprazole + antibiotics was 86%, a rate comparable with other PPI therapies, 81% (ITT); the odds ratio (OR) was 1.38 (95% CI = 1.09–1.75). A focused meta-analysis of 6 selected high-quality studies was produced an OR of this comparison that was closer to one (1.17, 95% CI = 0.89–1.54), with the results being statistically homogeneous. Sub-analysis that included only studies comparing different does of esomeprazole with omeprazole or pantoprazole did not reveal significant differences. No additional serious adverse events were reported. Conclusions: Esomeprazole-based triple therapy may effectively eradicate H. pylori infection and promote favorable outcome with good tolerance and offers comparable efficacy to omeprazole-based therapy.