bluuebunny/crossref_metadata_2025_split huggingface dataset:
Finite volume analysis of temperature effects induced by active MRI implants with cylindrical symmetry: 1. Properly working devices
Authors: Busch Martin HJ , Vollmann Wolfgang , Schnorr Jörg , Grönemeyer Dietrich HW 
Published: April 2005

Abstract
Background
Active Magnetic Resonance Imaging implants are constructed as resonators tuned to the Larmor frequency of a magnetic resonance system with a specific field strength. The resonating circuit may be embedded into or added to the normal metallic implant structure. The resonators build inductively coupled wireless transmit and receive coils and can amplify the signal, normally decreased by eddy currents, inside metallic structures without affecting the rest of the spin ensemble. During magnetic resonance imaging the resonators generate heat, which is additional to the usual one described by the specific absorption rate. This induces temperature increases of the tissue around the circuit paths and inside the lumen of an active implant and may negatively influence patient safety.

Methods
This investigation provides an overview of the supplementary power absorbed by active implants with a cylindrical geometry, corresponding to vessel implants such as stents, stent grafts or vena cava filters. The knowledge of the overall absorbed power is used in a finite volume analysis to estimate temperature maps around different implant structures inside homogeneous tissue under worst-case assumptions. The "worst-case scenario" assumes thermal heat conduction without blood perfusion inside the tissue around the implant and mostly without any cooling due to blood flow inside vessels.

Results
The additional power loss of a resonator is proportional to the volume and the quality factor, as well as the field strength of the MRI system and the specific absorption rate of the applied sequence. For properly working devices the finite volume analysis showed only tolerable heating during MRI investigations in most cases. Only resonators transforming a few hundred mW into heat may reach temperature increases over 5 K. This requires resonators with volumes of several ten cubic centimeters, short inductor circuit paths with only a few 10 cm and a quality factor above ten. Using MR sequences, for which the MRI system manufacturer declares the highest specific absorption rate of 4 W/kg, vascular implants with a realistic construction, size and quality factor do not show temperature increases over a critical value of 5 K.

Conclusion
The results show dangerous heating for the assumed "worst-case scenario" only for constructions not acceptable for vascular implants. Realistic devices are safe with respect to temperature increases. However, this investigation discusses only properly working devices. Ruptures or partial ruptures of the wires carrying the electric current of the resonance circuits or other defects can set up a power source inside an extremely small volume. The temperature maps around such possible "hot spots" should be analyzed in an additional investigation.
Tissue Doppler echocardiographic quantification. Comparison to coronary angiography results in Acute Coronary Syndrome patients
Authors: Donal Erwan , Raud-Raynier Pascale , Coisne Damien , Allal Joseph , Herpin Daniel 
Published: April 2005

Abstract
Background
Multiples indices have been described using tissue Doppler imaging (DTI) capabilities. The aim of this study was to assess the capability of one or several regional DTI parameters in separating control from ischemic myocardium.

Methods
Twenty-eight patients with acute myocardial infarction were imaged within 24-hour following an emergent coronary angioplasty. Seventeen controls without any coronary artery or myocardial disease were also explored. Global and regional left ventricular functions were assessed. High frame rate color DTI cineloop recordings were made in apical 4 and 2-chamber for subsequent analysis. Peak velocity during isovolumic contraction time (IVC), ejection time, isovolumic relaxation (IVR) and filling time were measured at the mitral annulus and the basal, mid and apical segments of each of the walls studied as well as peak systolic displacement and peak of strain.

Results
DTI-analysis enabled us to discriminate between the 3 populations (controls, inferior and anterior AMI). Even in non-ischemic segments, velocities and displacements were reduced in the 2 AMI populations. Peak systolic displacement was the best parameter to discriminate controls from AMI groups (wall by wall, p was systematically < 0.01). The combination IVC + and IVR< 1 discriminated ischemic from non-ischemic segments with 82% sensitivity and 85% specificity.

Conclusion
DTI-analysis appears to be valuable in ischemic heart disease assessment. Its clinical impact remains to be established. However this simple index might really help in intensive care unit routine practice.
Research: Is resection of tumours involving the pelvic ring justified? : A review of 49 consecutive cases
Authors: Yuen Alex , Ek Eugene T , Choong Peter FM 
Published: April 2005

Abstract
Introduction
Pelvic surgery is challenging and impacts significantly on limb and visceral function, thus, raising the question "is heroic surgery justifiable". This study assessed the functional, oncologic and surgical outcomes following pelvis tumour resections.

Methods
Between 1996–2003, 49 patients (mean age 43 years) underwent pelvic tumour resections- 38 primary malignant tumours, 5 secondary tumours and 6 benign tumours. Bone tumours comprised 5 osteosarcomas, 5 Ewings sarcomas, and 12 chondrosarcomas. Of the soft tumours, 9 were of neural origin. Tumours involved the ilium, acetabulum, pubic bones, sacrum or a combination of these. Functional assessment was performed and no patient had metastases at presentation.

Results
There were 41 limb sparing resections and 8 hindquarter amputations. Surgical margins were intralesional (1), marginal (13), wide (26), and radical (3). Of limb sparing surgery, prosthetic reconstructions were performed in 10 patients, biologic reconstructions in 6, a combination of these in 3 and no reconstruction in others. There was 1 intraoperative death, 7 local recurrences and 19 metastases. Death from disease occurred at a mean of 14.2 months with a mean followup of 27 (1–96) months. Amputation and periacetabular resections had worse functional outcomes. Emotional acceptance was surprisingly high.

Conclusion
Pelvic resections are complex. Functional outcome is significantly affected by surgery. Disease control is similar to limb tumours. Emotional acceptance of surgery in survivors was surprisingly high. Major pelvic resection for malignancy appears justified.
Monochorionic triamniotic triplet pregnancy with a co-triplet fetus discordant for congenital cystic adenomatoid malformation of the lung
Authors: Gul Ahmet , Aslan Halil , Cebeci Altan , Ceylan Yavuz , Tekirdag Ali Ismet 
Published: April 2005

Abstract
Background
Spontaneous monochorionic triamniotic pregnancy is rare and is at increased risk for pregnancy complications. The presence of an anomalous fetus further complicates the management.

Case presentation
We present a case of monochorionic triamniotic triplet pregnancy diagnosed at 15 weeks of gestation with one fetus having developed a multicystic lung lesion, suggestive of congenital cystic adenomatoid malformation (CCAM). At 24 weeks, the largest cyst measured 10 mm in diameter. We managed the pregnancy conservatively and delivered three live male fetuses with birth weights 1560 g, 1580 g and 1590 g at 35 weeks of gestation. Two newborns were admitted to the neonatal intensive care unit with respiratory distress, the third one died due to sepsis 7 days postpartum. One of the newborns was discharged healthy at 24 days postpartum. The newborn with CCAM developed a pneumothorax on the right side, recovered after treatment, and was discharged after one month. Computerized tomography (CT) of the infant at 3 months demonstrated two cystic lesions in the middle lobe of the right lung measuring 25 mm and 15 mm. A repeat CT of the infant at 6 months showed a 30 mm solitary cystic mass.

Conclusion
Monochorionic triamniotic triplet pregnancy with a co-triplet fetus discordant for CCAM, present rarely and can be managed conservatively. These findings may help in decision making and counselling of parents.
Study on Oxygen Quenching Processes of the Excited State Dendrimer Molecules
Authors: Momotake Atsuya , Horiuchi Hiroaki , Hayakawa Junpei , Mizutani Takuo , Nishimura Yoshinobu , Hiratsuka Hiroshi , Arai Tatsuo 
Published: April 2005

Abstract
Since the excited singlet state of the core stilbene in dendrimers G1–G4 has ca. 5-ns lifetime, oxygen quenched their excited singlet state producing the singlet oxygen. The efficiency of singlet oxygen production based on the quenching of the stilbene core is the highest in G4.
Continuum Regression
Authors: Sundberg Rolf 
Published: April 2005

AbstractWhen, in a multiple regression, regressors are near‐collinear, so‐called regularized or shrinkage regression methods can be highly preferable to ordinary least squares, by trading bias for variance. Continuum regression, introduced by Stone and Brooks in 1990, ties together several more classical regularized regression methods, such as principal components regression, partial least squares regression, and ridge regression.
StPetersburg School of Probability
Authors: Seneta Eugene 
Published: April 2005

AbstractThe term St. Petersburg School of Probability is used to describe the chief St. Petersburg mathematicians who worked on probabilistic problems, and mathematicians in other cities of the Russian Empire whose work influenced them. The St. Petersburg group is taken as beginning with the return from Paris of M. V. Ostrogradsky and V. Ya. Buniakovsky, whose subsequent probabilistic creativity was strongly influenced by Laplace'sThéorie analytique. Buniakovsky's association with Chebyshev led to the probabilistic flourishing of Chebyshev and his pupils Markov and Liapunov. Markov's creativity in Markov chains was stimulated by his antagonistic interaction with P. A. Nekrasov (Moscow), and his probabilistic oeuvre in general was initiated against a background of support by A. V. Vasiliev (Kazan).
Identifying stereoisomers of the asymmetric hydrogenation catalyst [Me‐BPE‐Rh(COD)]+BF
Authors: Fox Martin E. , McCague Raymond 
Published: April 2005

AbstractThe performance of a catalyst used in asymmetric synthesis is likely to be dependent upon its stereoisomeric purity. An impurity was detectable by 31P NMR in early development batches of the asymmetric hydrogenation catalyst [(S,S)‐Me‐BPE‐Rh(COD)]+BF made from the ligand bis((2S,5S)‐2,5‐dimethylphospholano)ethane [(S,S)‐Me‐BPE]. Its identity as a stereoisomer with one chiral and one meso‐phospholane ring was deduced by comparison of the 31P NMR spectra and GC traces of the ligand with a deliberately synthesized mixture of isomers. Interestingly, the impurity corresponded to a trans‐meso isomer formed by thermal (200°C) pyramidal inversion at phosphorus of the initially synthesized cis‐meso‐phospholane when the ligand was purified by distillation. Low levels of this trans‐meso/chiral impurity do not significantly impair the enantioselectivity of the rhodium complex as an asymmetric hydrogenation catalyst, but high levels of stereochemical impurities resulted in a loss of both enantioselectivity and activity. Therefore it is indeed important to establish that a catalyst used in asymmetric catalysis is sufficiently stereoisomerically pure. Owing to strict control of the stereochemical purity of the key hexane‐2,5‐diol intermediate, the impurity is not detected in production batches. Chirality 17:177–185, 2005. © 2005 Wiley‐Liss, Inc.
Configurational stability of 2‐benzoylcyclohexanone: Unexpected solvent effects on the rate of racemization
Authors: Tumambac Gilbert E. , Francis Christopher J. , Wolf Christian 
Published: April 2005

AbstractThe kinetics of the racemization of 2‐benzoylcyclohexanone 1 in hexanes, ethanol, and mixtures thereof have been investigated by time dependence of enantiomeric purity using enantioselective HPLC. In pure hexanes and ethanol, the racemization half‐lives were determined as 552 and 23.8 min, respectively, at 66°C. Surprisingly, racemization of 1 in mixtures of hexanes and ethanol was found to involve an induction period followed by a sigmoidal decrease of the enantiomeric excess with half‐lives varying between 11.5 and 24.0 min. This unexpected solvent influence on the rate of racemization of 1 was attributed to complex isomerization mechanisms involving three possibly interconverting enol tautomers of 1. Chirality 17:171–176, 2005. © 2005 Wiley‐Liss, Inc.
Complexes containing actin and spectrin from erythrocyte and brain
Authors: Lin Diane C. , Flanagan Michael D. , Lin Shin 
Published: April 2005

AbstractA complex of proteins with properties similar to those of erythrocyte spectrinband 4.1‐actin complex has been idientified in a preparation derived from bovine brain. The complex has an apparent sedimentation coefficient of about 26S, and contains brain spectrin (also called fodrin) and actin as major components. The actin in the complex is in the oligomeric form, which nucleates assembly of actin filaments that grow from the “barbed” end. The complex cross‐links actin filaments, resulting in an increase in low‐shear viscosity. Whether the complex contains a protein analogous to erythrocyte band 4.1 is not known. However, it can be demonstrated that brain spectrin has the capability to interact with band 4.1 in a way which increases its ability to cross‐link actin filaments.
Organizational forms of actin in 13762 ascites mammary tumor cell microvilli
Authors: Carraway Coralie A. Carothers , Jung Goeh , Carraway Kermit L. 
Published: April 2005

AbstractThe organization of microvillus actin and its associated proteins have been investigated in sublines of mammary ascites tumors (MAT) with mobile (MAT‐B1) and immobile (MAT‐C1) cell surface receptors. Microvilli isolated from these sublines differ in morphology (branched for MAT‐C1 versus unbranched for MAT‐B1) and the presence of a 58,000‐dalton polypeptide (58K). 58K is found associated with MAT‐C1 microvilli, microvillar cytoskeletons obtained by nonionic detergent extractions, and microvillar membranes prepared under conditions which depolymerize actin microfilaments. By extraction with actin‐stabilizing buffers (isotonic Triton‐Mg‐ATP) microvillar actin can be fractionated into four forms. About 40% of the actin is sedimented at low speed (7,500g, 15 min). The pellets contain microfilaments; actin and α‐actinin are the predominant proteins. High‐speed pellets from these low‐speed supernates contain about 10% of the actin as a transmembrane complex with a cell surface glycoprotein (cytoskeleton‐associated glycoprotein, [CAG] 75–80,000 daltons) in MAT‐B1 cells or with CAG and 58K in MAT‐C1 cells. Transmembrane complexes can be purified from MAT‐B1 and MAT‐C1 microvillar membranes in Triton‐containing buffer by gel filtration or sucrose density gradient centrifugation. The presence of only CAG and actin in the MAT‐B1 transmembrane complex strongly suggests the direct interaction of actin and a cell surface component. The high‐speed supernates contain soluble actin. By gel filtration or rate‐zonal sucrose density gradient centrifugation about 30% of the microvillar actin is found as small oligomers and about 10% as G‐actin in this extraction buffer. We suggest that the actin‐containing transmembrane complexes may serve as membrane‐association sites for oligomeric actin segments and microfilaments and as initiation sites for actin polymerization.
Calcium regulation of the actin‐mediated cytoskeletal transformation of sea urchin coelomocytes
Authors: Henson J. H. , Schatten G. 
Published: April 2005

AbstractCoelomocytes from several echinoderm species undergo an actin‐mediated cytoskeletal transformation once subjected to hypotonic shock. In this study, coelomocytes from the sea urchins Lytechinus variegatus and Arbacia punctulata were induced to “transform” by treatment with > 5 μM of the calcium ionophore A23187 in the presence of external Ca++. The dependence of ionophore transformation on external Ca++ and the lack of chlorotetracycline staining indicates that these cells rely on external Ca++ sources. NBD‐phallacidin (7‐Nitrobenz‐2‐oxa‐1,3‐diazole‐phallacidin) staining of lysolecithin permeabilized cells and wholemount transmission electron microscopy (TEM) show that similar reorganizations of the actin cytoskeleton take place during hypotonic shock and ionophore transformation, although actin filament bundling is less apparent in A23187‐treated cells. As has been shown with hypotonic shock transformation, the ionophore elicited shape change is inhibited by anticalmodulin drugs. Greater than 10 μM concentrations of W 13 inhibit filopod formation, while this drug's less active structural analogue, W 12, exhibits no effects. W 13 also appears to disrupt actin filament‐membrane associations in the cells. Fluorescent localization of calmodulin using a photooxidized derivative of trifluoperazine indicates a general cytoplasmic distribution with some concentration in filopod core bundles. Coelomocyte transformation may be an example of a cellular shape change regulated by Ca++ through the action of calmodulin modulation of actin‐membrane interactions.
Effect of cytochalasin D on smooth muscle contraction
Authors: Adler Kenneth B. , Krill Judith , Alberghini Tod V. , Evans John N. 
Published: April 2005

AbstractCylindrical segments of extraparenchymal pulmonary artery (essentially a preparation of smooth muscle with regard to contractile capability) were isolated from adult male rats. They were mounted in an isometric muscle bath in physiological salt solution (PSS) in an environment of 95% O2/ CO2. After allowing 1 h for equilibration, the maximum force generated by the tissue in response to a depolarizing solution was determined. After relaxation, vessels were incubated for 1 h in one of several concentrations of cytochalasin D (CD) (0.01, 0.05, 0.5, 1, 10 μg/ml) and the response to stimulation retested immediately after returning to PSS, and then at 30 minute intervals up to 2 h.CD inhibited the ability of vascular smooth muscle to generate force (contract) in a concentration‐dependent manner. The inhibitory effect was reversible within a short period of time. Quantitative electron microscopic examination of these vessels suggested that CD disrupts the integrity of myofilaments, especially at sites of “dense bodies.” Our results indicate that a percentage of actin in smooth muscle cells is not permanently in the filamentous “F” form, but is part of the G:F actin system of the cell, labile to polymerization:depolymerization. The ability of smooth muscle cells to generate force could depend on the proper functioning of the F:G actin “treadmill”.
Intracellular movement of fodrin
Authors: Cheney Richard , Hirokawa Nobutaka , Levine Joel , Willard Mark 
Published: April 2005

AbstractFodrin is an actin/calmodulin‐binding protein with similarities to spectrin (erythrocytes) and TW 260/240 (brush border). It is concentrated beneath the plasma membranes of neurons and other cells. We have observed translocations of fodrin in both neurons and lymphocytes. Newly synthesized, radiolabeled fodrin moves down axons at a maximum velocity (about 50 mm/day) that is slower than the most rapidly axonally transported proteins (group I). A portion of fodrin appears to move more slowly at velocities (1–10 mm/day) resembling those of actin and myosin (group IV) and tubulin and neurofilament proteins (group V). In lymphocytes, when certain surface antigens are induced by cross‐linking agents to migrate to one pole of the cell and form a cap, fodrin redistributes beneath the membrane and forms a subcap. The movements of fodrin in lympohocyte capping and in the axonal transport of group IV polypeptides have certain similarities. In both cases, the redistribution of fodrin is accompanied by concomitant redistributions of actin, myosin, and calmodulin, and both processes proceed at similar velocities. We consider the possibilities that these two processes are related, both being driven by a submembrane force‐generating system comprising in part actin, myosin, and fodrin, and that fodrin serves to link various organelles or proteins to this system.
Amino acid alterations in the benA (β‐tubulin) gene of Aspergillus nidulans that confer benomyl resistance
Authors: Jung M. Katherine , Wilder Isaac B. , Oakley Berl R. 
Published: April 2005

AbstractWe report the cloning and sequencing of 18 mutant alleles of the benA, β‐tubulin gene of Aspergillus nidulans that confer resistance to the benzimidazole antifungal, antimicrotubule compounds benomyl, carbendazim, nocodazole, and thia‐bendazole. In 12 cases, amino acid 6 was changed from histidine to tyrosine or leucine. In four cases, amino acid 198 was changed from glutamic acid to aspartic acid, glutamine, or lysine. In two cases, amino acid 200 was altered from phenylalanine to tyrosine. These data, along with previous data indicating that amino acid 165 is involved in the binding of the R2 group of these compounds [Jung and Oakley, 1990: Cell Motil. Cytoskeleton 17:87‐94], suggest that regions of β‐tubulin containing amino acids 6, 165, and 198‐200 interact to form the binding site of benzimidazole antimicrotubule agents. These results also suggest that the presence of phenylalanine at amino acid 200 contributes to the great sensitivity of many fungi to benzimidazole antimicrotubule agents. © 1992 Wiley‐Liss, Inc.
Control of organelle transport in melanophores: Regulation of CA2+ and cAMP levels
Authors: Thaler Catherine D. , Haimo Leah T. 
Published: April 2005

AbstractMelanophores of the cichlid Tilapia mossambica can be induced to aggregate pigment by addition of epinephrine to the medium, suggesting adrenergic control of this transport. The melanophore response to adrenergic stimulation was examined using agonists and antagonists that are highly specific for each alpha‐adrenoceptor subclass. The signal transduction mechanism of each subclass is unique: stimulation of alpha1 receptors results in a rise in intracellular free Ca2+, while alpha2 stimulation results in decreased cAMP levels [Exton, 1985: Am. J. Physiol. 248:E633–E647 ]. Each alpha1 or alpha2 specific agonist tested showed a dose dependent ability to induce aggregation and each was able to effect complete aggregation of pigment, suggesting that aggregation can be mediated either by elevating Ca2+ or by lowering cAMP. However, in the presence of either an alpha1 or an alpha2 receptor antagonist, none of the agonists were able to induce significant aggregation, suggesting that changes in levels of both messengers are required for pigment aggregation in the melanophores. Moreover, experiments in which intracellular levels of Ca2+ or cAMP were perturbed, using BAPTA and forskolin, respectively, indicated that elevating Ca2+ in the presence of high cAMP is not sufficient to induce aggregation and, conversely, that lowering cAMP levels in the presence of reduced Ca2+ is not sufficient to induce pigment aggregation. These data indicate that the concentrations of both cAMP and Ca2+ are important in regulating pigment aggregation in teleost melanophores, and suggest that maximal aggregation of pigment requires altering the levels of both messengers. © 1992 Wiley‐Liss, Inc.