bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term infusion of Met5-enkephalin fails to protect murine hearts against ischemia-reperfusion injury
Authors: Kuzume Koh , Kuzume Kazuyo , Cao Zhiping , Liu Lijuan , Van Winkle Donna M.
Published: November 2004

Recently, we reported that exogenous administration of Met5-enkephalin (ME) for 24 h reduces infarct size after ischemia-reperfusion in rabbits. In the present study, we tested whether ME-induced cardioprotection is exhibited in murine hearts and whether chronic infusion of this peptide can render hearts tolerant to ischemia. Barbiturate-anesthetized open-chest mice (C57BL/6J) were subjected to regional myocardial ischemia-reperfusion (45 min of occlusion and 20 min of reperfusion). Mice received saline vehicle or ME for 24 h or 2 wk before undergoing regional myocardial ischemia-reperfusion or for 24 h followed by a 24-h delay before regional myocardial ischemia-reperfusion. Infarct size was measured with propidium iodide and is expressed as a percentage of the area at risk. Infarcts were smaller after infusion of ME for 24 h than with vehicle control: 49.2 ± 9.0% vs. 22.2 ± 3.2% ( P < 0.01). In contrast, administration of ME for 2 wk failed to elicit cardioprotection: 36.5 ± 9.1% and 41.4 ± 8.2% for control and ME, respectively ( P = not significant). When a 24-h delay was imposed between the end of drug treatment and the onset of the ischemic insult, cardioprotection was lost: 38.5 ± 6.1% and 42.8 ± 6.6% for control and ME, respectively ( P = not significant). Chronic sustained exogenous infusion of the endogenously produced opioid peptide ME is associated with loss of the cardioprotection that is observed with 24 h of infusion. Furthermore, in this in vivo murine model, ME failed to induce delayed tolerance to myocardial ischemia-reperfusion.
Direct measurement of transmural laminar architecture in the anterolateral wall of the ovine left ventricle: new implications for wall thickening mechanics
Authors: Harrington Katherine B. , Rodriguez Filiberto , Cheng Allen , Langer Frank , Ashikaga Hiroshi , Daughters George T. , Criscione John C. , Ingels Neil B. , Miller D. Craig
Published: November 2004

Laminar, or sheet, architecture of the left ventricle (LV) is a structural basis for normal systolic and diastolic LV dynamics, but transmural sheet orientations remain incompletely characterized. We directly measured the transmural distribution of sheet angles in the ovine anterolateral LV wall. Ten Dorsett-hybrid sheep hearts were perfusion fixed in situ with 5% buffered glutaraldehyde at end diastole and stored in 10% formalin. Transmural blocks of myocardial tissue were excised, with the edges cut parallel to local circumferential, longitudinal, and radial axes, and sliced into 1-mm-thick sections parallel to the epicardial tangent plane from epicardium to endocardium. Mean fiber directions were determined in each section from five measurements of fiber angles. Each section was then cut transverse to the fiber direction, and five sheet angles (β) were measured and averaged. Mean fiber angles progressed nearly linearly from −41° (SD 11) at the epicardium to +42° (SD 16) at the endocardium. Two families of sheets were identified at approximately +45° (β+) and −45° (β−). In the lateral region ( n = 5), near the epicardium, sheets belonged to the β+ family; in the midwall, to the β− family; and near the endocardium, to the β+ family. This pattern was reversed in the basal anterior region ( n = 4). Sheets were uniformly β− over the anterior papillary muscle ( n = 2). These direct measurements of sheet angles reveal, for the first time, alternating transmural families of predominant sheet angles. This may have important implications in understanding wall mechanics in the normal and the failing heart.
CCK inhibits the orexigenic effect of peripheral ghrelin
Authors: Kobelt Peter , Tebbe Johannes J. , Tjandra Ines , Stengel Andreas , Bae Hi-Gung , Andresen Viola , van der Voort Ivo R. , Veh Rüdiger W. , Werner Christoph R. , Klapp Burghard F. , Wiedenmann Bertram , Wang Lixin , Taché Yvette , Mönnikes Hubert
Published: November 2004

CCK and ghrelin exert antagonistic effects on ingestive behavior. The aim of the present study was to investigate the interaction between ghrelin and CCK administered peripherally on food intake and neuronal activity in specific hypothalamic and brain stem nuclei, as assessed by c-Fos-like immunoreactivity (c-FLI) in nonfasted rats. Ghrelin (13 μg/kg body wt) injected intraperitoneally significantly increased the cumulative food intake when measured at 30 min and 1 h after injection, compared with the vehicle group (2.9 ± 1.0 g/kg body wt vs. 1.2 ± 0.5 g/kg body wt, P < 0.028). Sulfated CCK octapeptide (CCK-8S) (2 or 25 μg/kg body wt) injected simultaneously blocked the orexigenic effect of ghrelin (0.22 ± 0.13 g/kg body wt, P < 0.001 and 0.33 ± 0.23 g/kg body wt, P < 0.0008), while injected alone, both doses of CCK-8S exerted a nonsignificant trend to reduce food intake. Ghrelin (13 μg/kg body wt ip) markedly increased the number of c-FLI-positive neurons per section in the arcuate nucleus (ARC) compared with vehicle (median: 31.35 vs. 9.86, P < 0.0001). CCK-8S (2 or 25 μg/kg body wt ip) had no effect on neuronal activity in the ARC, as assessed by c-FLI (median: 5.33 and 11.21 cells per section), but blocked the ghrelin-induced increase of c- fos expression in this area when both peptides were administered simultaneously (median: 13.33 and 12.86 cells per section, respectively). Ghrelin at this dose had no effect on CCK-induced stimulation of c- fos expression in the paraventricular nucleus of the hypothalamus and the nucleus of the solitary tract. These results suggest that CCK abolishes ghrelin-induced food intake through dampening increased ARC neuronal activity.
Sequences of Predictive Saccades Are Correlated Over a Span of ∼2 s and Produce a Fractal Time Series
Authors: Shelhamer Mark
Published: November 2004

We previously demonstrated that there is an abrupt (rather than smooth) transition between reactive and predictive modes of eye-movement tracking of target lights (a phase transition). We also found evidence that the sequence of eye movements in the reactive mode was independent, whereas those in the predictive mode were correlated and possibly formed a random fractal sequence. Here we confirm the finding of fractal structure by quantifying the rate of decay of nonlinear forecasting when applied to these data. We also estimate the window over which consecutive trials are correlated and show that the duration of this window is fixed in time rather than number of trials. These results have implications for the neural mechanisms that drive predictive movements.
Functional genomics of the dopaminergic system in hypertension
Authors: Zeng Chunyu , Sanada Hironobu , Watanabe Hidetsuna , Eisner Gilbert M. , Felder Robin A. , Jose Pedro A.
Published: November 2004

Abnormalities in dopamine production and receptor function have been described in human essential hypertension and rodent models of genetic hypertension. Under normal conditions, D1-like receptors (D1and D5) inhibit sodium transport in the kidney and intestine. However, in the Dahl salt-sensitive and spontaneously hypertensive rats (SHRs) and in humans with essential hypertension, the D1-like receptor-mediated inhibition of epithelial sodium transport is impaired because of an uncoupling of the D1-like receptor from its G protein/effector complex. The uncoupling is receptor specific, organ selective, nephron-segment specific, precedes the onset of hypertension, and cosegregates with the hypertensive phenotype. The defective transduction of the renal dopaminergic signal is caused by activating variants of G protein-coupled receptor kinase type 4 (GRK4: R65L, A142V, A486V). The GRK4 locus is linked to and GRK4 gene variants are associated with human essential hypertension, especially in salt-sensitive hypertensive subjects. Indeed, the presence of three or more GRK4 variants impairs the natriuretic response to dopaminergic stimulation in humans. In genetically hypertensive rats, renal inhibition of GRK4 expression ameliorates the hypertension. In mice, overexpression of GRK4 variants causes hypertension either with or without salt sensitivity according to the variant. GRK4 gene variants, by preventing the natriuretic function of the dopaminergic system and by allowing the antinatriuretic factors (e.g., angiotensin II type 1 receptor) to predominate, may be responsible for salt sensitivity. Subclasses of hypertension may occur because of additional perturbations caused by variants of other genes, the quantitative interaction of which may vary depending upon the genetic background.
The Heuristic Structure of Scientific Knowledge
Authors: Eraña Ángeles , Martínez Sergio
Published: November 2004

We examine two major perspectives in the literature on domain specificity in cognition: in one of them cognitive modules are "intuitive theories"; in the other they are dispositional structures. Both of these positions accept that there is a continuous line from ordinary to scientific reasoning; nevertheless they interpret this continuity differently. We propose an alternative way of understanding the relation between ordinary and scientific reasoning: the continuity thesis holds because heuristic structures play a fundamental role in both types of reasoning. Our main contention is that cognitive modules can be thought of as heuristic structures and that, since science is a complex of practices that embody different heuristic structures, science should be understood as a complex of cognitive modules.
Emergence of Graphing Practices in Scientific Research
Authors: Roth Wolff-Michael
Published: November 2004

Graphing has long counted as one of the quintessential process skills that scientists apply independently of particular situations. However, recent expert/expert studies showed that when asked to interpret graphs culled from undergraduate courses of their own disciplines, scientists were far from perfect in providing interpretations that a course instructor would have accepted as correct. Drawing on five years of fieldwork, the present study was designed to investigate graphs and graph-related skills in scientific research. In addition to the fieldwork, a think-aloud protocol was used to elicit scientists' graph interpretations both on familiar and unfamiliar graphs. The analyses show that graph-related skills such as perceiving relevant graphical detail and interpreting the source of this detail emerge in the research process and are related to the scientists' increasing familiarity with a research object, instrumentation, and their understanding of the transformation process that turns raw data into graphs. When scientists do not know the natural object represented in a graph and are unfamiliar with the details of the corresponding data collection protocol, they often focus on graphical features that do not pertain to the phenomenon represented and therefore do not arrive at the correct interpretations. Based on these data, it is proposed that graphs are not only the outcomes of scientific research but also, in important ways, constitute representations that bear metonymic relations to the research context, most importantly to instrumentation, natural phenomenon, and the mathematical transformations used to produce the graphs from the raw data. I draw on the semantics of symbolic systems for articulating competencies and breakdowns in scientists' graphing-related practices.
On “Converting” Hand Pain Into Psychological Pain
Authors: Ciano-Federoff Lynda M. , Sperry Jeannie A.
Published: November 2004

A 36-year-old woman with a history of teenage trauma presented to a pain clinic with unexplained hand pain and numbness. The patient was ultimately diagnosed with post-traumatic stress disorder with a conversion reaction. Because the trauma was taken to be significant in her symptomatology, she was referred for exposure-based therapy. Although psychological distress increased over treatment, her reported physical symptoms and an objectively measured index of symptoms both improved dramatically. Because many patients with unconventional presentations are overutilizers of medical resources, addressing the “cause” of the distress (e.g., trauma) can be advantageous for both patient and medical personnel.
Fixed-Role Therapy With Multiple Paraphilias
Authors: Horley James
Published: November 2004

Paraphilias, or sexually deviant behaviors, are especially difficult to address when an individual displaysmore than one sexual deviation at one time. Acase of an incarcerated forensic client who displayed symptoms of sadism, masochism, and hebephilia is described. Fixed-role therapy (FRT), a dramaturgical approach to treatmentwhere a client enacts a new character or role based on how he or she would like to act, was employed with at least short-termsuccess in one case. Some of the advantages and limitations of FRT are discussed.
Synthesis and Investigation of ZnS Nanoparticles Adsorbed on Functionalised Silica Particles
Authors: Ethiraj A.S. , Hebalkar N. , Sainkar S.R. , Urban J. , Kulkarni S.K.
Published: November 2004

The synthesis of monodispersed ZnS nanoparticles (∼1.2 nm) stabilised with thioglycerol molecules which have been attached to functionalised silica particles is reported. The coupling agent used was 3-aminopropyltrimethoxysilane. The chemical bonding was studied by Fourier transform infrared spectroscopy. TEM of these particles clearly shows a uniform coating of ZnS on silica particles. These SiO2@ZnS core shell particles were also studied using characterisation techniques such as optical absorption spectroscopy, X-ray diffraction and EDAX.
Computation of Composite Hardness of Coated Systems
Authors: Puchi-Cabrera E.S.
Published: November 2004

The present communication re-examines the basis of a previous model (E. S. Puchi-Cabrera: Surf. Coat. Technol., 2002, 160, 177 – 186) for the computation of the composite hardness of coated systems as a function of the relative indentation depth (RID), applicable to monolayer coatings. The results initially derived from simple geometrical considerations are compared with those obtained taking into account the volumes of the plastic zones of the coating and substrate under the indenter, as proposed by several models already published. A similar expression for the rate of change of the substrate volume fraction with the RID is obtained from both approaches. The consideration of the validity of a linear law of mixtures for the determination of the composite hardness is also reexamined, assuming that the composite hardness could be given by a harmonic law of mixtures. Both the previous model and the one developed from the introduction of a harmonic law of mixtures are extended to deal with multilayer coatings. In this case, the composite hardness as a function of the RID is calculated in terms of the volume fraction and hardness of each of the layer materials which compose the multilayer coating, and also two constants which characterise the behaviour of the coating. The results derived from the new model based on the harmonic law of mixtures are then compared with those obtained from the previous model, employing a number of systems involving both monolayer and multilayer coatings deposited onto different substrates.
Effect of a Thin Hard Chromium Coating on Fatigue Behaviour of 4140 Steel
Authors: Ortiz-Mancilla M.J. , Mariño-Berroterán C. , Berríos-Ortiz J.A. , Mesmacque G. , Puchi-Cabrera E.S.
Published: November 2004

The fatigue properties of a quenched and tempered (Q&T) 4140 (NiCrMo) steel coated with a hard Cr deposit, ∼7 μm thick were investigated. The fatigue properties of the coated specimens were evaluated in the as deposited condition. The results obtained showed that both fatigue life and fatigue limit are substantially reduced in comparison with the uncoated material. The reduction in fatigue life was computed from the Basquin parameters of the materials tested under different alternating stresses. It was shown that the fatigue life of the steel substrate can be reduced by up to 88%, whereas the fatigue limit can be reduced by, ∼21%, as a consequence of the coating. SEM observations showed that the fatigue fracture of the coated specimens initiates at the substrate–deposit interface and that the coating remains well adhered to the substrate during fatigue testing. The fracture surfaces of the specimens tested showed multiple crack initiation sites which led to the conclusion that the coating acts as a crack source for the steel substrate.
Codeposition of Cerium Oxide with Nickel and Cobalt: Correlation between Microstructure and Microhardness
Authors: Cârâc G. , Benea L. , Iticescu C. , Lampke T. , Steinhäuser S. , Wielage B.
Published: November 2004

Composite layers were obtained by electrochemical deposition of cobalt or nickel from a plating bath with cerium oxide as dispersed particles. The changes in microstructure and microhardness of the composite were studied in correlation with the number of oxide particles incorporated. It was found that the presence of cerium oxide (CeO2) particles has an influence on the codeposition process. The CeO2 included particles lead to structural modifications of the metal matrix and have an effect on the mechanical as well as the surface properties of the composite.
Synthesis and Characterisation of Sol–gel Derived Nanostructured Composite of ZnO/PVP Thin Films
Authors: Du T. , Ilegbusi O.J.
Published: November 2004

Pure ZnO films and ZnO nanoparticle dispersed polyvinylpyrrolidone (PVP) films were prepared on a Pyrex glass substrate by sol–gel dip coating using a zinc acetate precursor. The thin film is extensively characterised for its surface morphology, chemistry, thickness and nanocrystallite size, using various advanced analytical techniques such as SEM, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. Under the given processing conditions, ZnO semiconductor thin films with nanocrystallite size 20–30 nm were obtained, and the ZnO nanoparticle size in the PVP matrix increased with increase in ZnO content.
Molecular dissection of Pax6 function: the specific roles of the paired domain and homeodomain in brain development
Authors: Haubst Nicole , Berger Joachim , Radjendirane Venugopal , Graw Jochen , Favor Jack , Saunders Grady F. , Stoykova Anastassia , Götz Magdalena
Published: November 2004

The transcription factor Pax6 plays a key role during development of various organs, including the brain where it affects cell fate, cell proliferation and patterning. To understand how Pax6 coordinates these diverse effects at the molecular level, we examined the role of distinct DNA-binding domains of Pax6, the homeodomain (HD), the paired domain (PD) and its splice variant (5a), using loss- and gain-of-function approaches. Here we show that the PD is necessary for the regulation of neurogenesis, cell proliferation and patterning effects of Pax6, since these aspects are severely affected in the developing forebrain of the Pax6Aey18 mice with a deletion in the PD but intact homeo- and transactivation domains. In contrast, a mutation of the HD lacking DNA-binding (Pax64Neu) resulted in only subtle defects of forebrain development. We further demonstrate distinct roles of the two splice variants of the PD. Retrovirally mediated overexpression of Pax6 containing exon 5a inhibited cell proliferation without affecting cell fate, while Pax6 containing the canonical form of the PD lacking exon 5a affected simultaneously cell fate and proliferation. These results therefore demonstrate a key role of the PD in brain development and implicate splicing as a pivotal factor regulating the potent neurogenic role of Pax6.
The COUP-TF nuclear receptors regulate cell migration in the mammalian basal forebrain
Authors: Tripodi Marco , Filosa Alessandro , Armentano Maria , Studer Michèle
Published: November 2004

Cells migrate via diverse pathways and in different modes to reach their final destinations during development. Tangential migration has been shown to contribute significantly to the generation of neuronal diversity in the mammalian telencephalon. GABAergic interneurons are the best-characterized neurons that migrate tangentially, from the ventral telencephalon, dorsally into the cortex. However, the molecular mechanisms and nature of these migratory pathways are only just beginning to be unravelled. In this study we have first identified a novel dorsal-to-ventral migratory route, in which cells migrate from the interganglionic sulcus, located in the basal telencephalon between the lateral and medial ganglionic eminences, towards the pre-optic area and anterior hypothalamus in the diencephalon. Next, with the help of transplantations and gain-of-function studies in organotypic cultures,we have shown that COUP-TFI and COUP-TFII are expressed in distinct and non-overlapping migratory routes. Ectopic expression of COUP-TFs induces an increased rate of cell migration and cell dispersal, suggesting roles in cellular adhesion and migration processes. Moreover, cells follow a distinct migratory path, dorsal versus ventral, which is dependent on the expression of COUP-TFI or COUP-TFII, suggesting an intrinsic role of COUP-TFs in guiding migrating neurons towards their target regions. Therefore, we propose that COUP-TFs are directly involved in tangential cell migration in the developing brain, through the regulation of short- and long-range guidance cues.
Neural crest cell lineage segregation in the mouse neural tube
Authors: Wilson Yvette M. , Richards Kay L. , Ford-Perriss Miriam L. , Panthier Jean-Jacques , Murphy Mark
Published: November 2004

Neural crest (NC) cells arise in the dorsal neural tube (NT) and migrate into the embryo to develop into many different cell types. A major unresolved question is when and how the fate of NC cells is decided. There is widespread evidence for multipotential NC cells, whose fates are decided during or after migration. There is also some evidence that the NC is already divided into subpopulations of discrete precursors within the NT. We have investigated this question in the mouse embryo. We find that a subpopulation of cells on the most dorsomedial aspect of the NT express the receptor tyrosine kinase Kit(previously known as c-kit), emigrate exclusively into the developing dermis,and then express definitive markers of the melanocyte lineage. These are thus melanocyte progenitor cells. They are generated predominantly at the midbrain-hindbrain junction and cervical trunk, with significant numbers also in lower trunk. Other cells within the dorsal NT are Kit–,migrate ventrally, and, from embryonic day 9.5, express the neurotrophin receptor p75. These cells most likely only give rise to ventral NC derivatives such as neurons and glia. The p75+ cells are located ventrolateral to the Kit+ cells in areas of the NT where these two cell types are found. These data provide direct in vivo evidence for NC lineage segregation within the mouse neural tube.
In vivo evidence for short- and long-range cell communication in cranial neural crest cells
Authors: Teddy Jessica M. , Kulesa Paul M.
Published: November 2004

The proper assembly of craniofacial structures and the peripheral nervous system requires neural crest cells to emerge from the neural tube and navigate over long distances to the branchial arches. Cell and molecular studies have shed light on potential intrinsic and extrinsic cues, which, in combination,are thought to ensure the induction and specification of cranial neural crest cells. However, much less is known about how migrating neural crest cells interpret and integrate signals from the microenvironment and other neural crest cells to sort into and maintain the stereotypical pattern of three spatially segregated streams. Here, we explore the extent to which cranial neural crest cells use cell-to-cell and cell-environment interactions to pathfind. The cell membrane and cytoskeletal elements in chick premigratory neural crest cells were labeled in vivo. Three-dimensional reconstructions of migrating neural crest cells were then obtained using confocal static and time-lapse imaging. It was found that neural crest cells maintained nearly constant contact with other migrating neural crest cells, in addition to the microenvironment. Cells used lamellipodia or short, thin filopodia (1-2 μm wide) for local contacts (<20 μm). Non-local, long distance contact (up to 100 μm) was initiated by filopodia that extended and retracted, extended and tracked, or tethered two non-neighboring cells. Intriguingly, the cell-to-cell contacts often stimulated a cell to change direction in favor of a neighboring cell's trajectory. In summary, our results present in vivo evidence for local and long-range neural crest cell interactions, suggesting a possible role for these contacts in directional guidance.
Planar cell polarity in theDrosophilaeye is directed by graded Four-jointed and Dachsous expression
Authors: Simon Michael A.
Published: November 2004

Planar cell polarity (PCP) occurs when the cells of an epithelium are polarized along a common axis lying in the epithelial plane. During the development of PCP, cells respond to long-range directional signals that specify the axis of polarization. In previous work on the Drosophilaeye, we proposed that a crucial step in this process is the establishment of graded expression of the cadherin Dachsous (Ds) and the Golgi-associated protein Four-jointed (Fj). These gradients were proposed to specify the direction of polarization by producing an activity gradient of the cadherin Fat within each ommatidium. In this report, I test and confirm the key predictions of this model by altering the patterns of Fj, Ds and Fat expression. It is shown that the gradients of Fj and Ds expression provide partially redundant positional information essential for specifying the polarization axis. I further demonstrate that reversing the Fj and Ds gradients can lead to reversal of the axis of polarization. Finally, it is shown that an ectopic gradient of Fat expression can re-orient PCP in the eye. In contrast to the eye, the endogenous gradients of Fj and Ds expression do not play a major role in directing PCP in the wing. Thus, this study reveals that the two tissues use different strategies to orient their PCP.
Effect of a compensated Jaffé creatinine method on the estimation of glomerular filtration rate
Authors: Chan Michael HM , Ng KF , Szeto CC , Lit Lydia CW , Chow KM , Leung CB , Suen Michael WM , Li Phillip KT , Lam Christopher WK
Published: November 2004

Background: Roche Diagnostics has issued new c-fas calibrators for its automated systems. These produce creatinine values that are more comparable with those obtained by high-performance liquid chromatography. However, this results in an underestimation of measured creatinine at concentrations below 155 μmol/L and an overestimation at concentrations above this value.

Methods: Serum and urine creatinine concentrations were prospectively determined on samples from 60 patients using the new (compensated) and old (uncompensated) c-fas calibrators, and Passing-Bablok regression analysis was performed. The regression equations thus determined were then used retrospectively to determine the compensated creatinine results (i.e. those results that would have been obtained using the new calibrator) in those serum and urine samples analysed in the previous year using the old uncompensated c-fas calibrator. The compensated creatinine results were then used to estimate the glomerular filtration rate (GFR) by calculating creatinine clearance. This was done by using the formula: UV/Pt, in which U represents the urinary creatinine concentration (μmol/L), V the urinary collection volume (mL), P the serum creatinine concentration (μmol/L) and t the urinary collection time (min). It was also calculated using the abbreviated Modification of Diet in Renal Disease study group (MDRD) formula.

Results: The creatinine clearance as determined using either the UV/Pt calculation or the MDRD formula overestimated GFR by ~30% and ~50%, respectively, in normal individuals with a serum creatinine concentration below 155 μmol/L. However, in patients with mild to moderate renal failure (serum creatinine from 155 to 500 μmol/L), changes in creatinine clearances determined by the two procedures were minimal.

Conclusion: When laboratories introduce this new, compensated calibrator into practice, it may be appropriate to discuss its potential impact with clinical staff who monitor patients using creatinine clearance.
Navigation as a quality management tool in cochlear implant surgery
Authors: Schipper Jörg , Aschendorff Antje , Arapakis Iakovos , Klenzner Thomas , Teszler Christian Barna , Ridder Gerd Jürgen , Laszig Roland
Published: November 2004

This cadaver study assessed the value of navigation in cochlear implant surgery. Cochlear implantation was simulated on a cadaver using a Stryker-Leibinger navigation system and a Nucleus 24 Contour implant. A conventional surgical strategy consisting of mastoidectomy, posterior tympanotomy, and cochleostomy was performed. The navigated surgical procedure was evaluated for accuracy, reliability, reproducibility, and practicability. The technology of computer-assisted surgery is applicable in cochlear implantation and beneficial in as much as the navigation-controlled implantation constitutes a non-invasive instrument of quality management. Nevertheless, in order to keep the point accuracy below one millimeter, a referencing methodusing concealed bordering anatomical structures may be further needed to perform the cochleostomy reliably under the guidance of a navigation system. More reproducible reference systems are needed if navigated lateral skull base surgery is to be fully relied upon.
Teflon–induced granuloma: a source of false positive positron emission tomography and computerized tomography interpretation
Authors: Hewitt Richard J.D. , Singh Arvind , Wareing Michael J.
Published: November 2004

Patients diagnosed with malignancy often undergo combined positron emissiontomography (PET) and computerized tomography (CT) to investigate possible metastases. This report presents a case in which, in the investigation of suspected pulmonary malignancy, combined PET and CT images suggested a malignant lesion at the level of the vocal fold. Biopsy of the lesion, however, confirmed the clinical diagnosis of a Teflon granuloma. The case highlights the potential for a false positive report during scanning of patients who have had vocal fold injection.
On the “General Acceptance” of Handwriting Identification Principles
Authors: Saks MJ , VanderHaar H
Published: November 2004

Informed by the admissibility requirements of the broad and narrow Frye tests as well as Daubert's general acceptance factor, the present study elicited the views of a homogeneous group of forensic document examiners and a heterogeneous group of handwriting scientists regarding the degree to which a set of principles relating to the nature of handwriting and its identification were generally accepted within the respondents' fields. Among forensic document examiners, the greatest agreement was found concerning the process of examination, and somewhat less agreement on other matters. Forensic document examiners and handwriting scientists appear not to agree on the acceptability of most of the propositions.
Does Carcass Enrichment Alter Community Structure of Predaceous and Parasitic Arthropods? A Second Test of the Arthropod Saturation Hypothesis at the Anthropology Research Facility in Knoxville, Tennessee
Authors: Schoenly KG , Shahid SA , Haskell NH , Hall RD
Published: November 2004

In a second test of an arthropod saturation hypothesis, we analyzed if the on-campus Anthropology Research Facility (ARF) at the University of Tennessee, Knoxville, with its 20+ yr history of carcass enrichment, is comparable to non-enriched sites in community structure of predatory and parasitic arthropods that prey upon the sarcosaprophagous fauna. Over a 12-day period in June 1998, using pitfall traps and sweep nets, 10,065 predaceous, parasitic, and hematophagous (blood-feeding) arthropods were collected from freshly euthanized pigs (Sus scrofa L.) placed at ARF and at three surrounding sites various distances away (S2-S4). The community structure of these organisms was comparable in most paired-site tests with respect to species composition, colonization rates, and evenness of pitfall-trap abundances on a per carcass basis. Site differences were found in rarefaction tests of both sweep-net and pitfall-trap taxa and in tests of taxonomic evenness and ranked abundances of sweep-net samples. Despite these differences, no evidence was found that the predatory/parasitic fauna at ARF was impoverished with fewer but larger populations as a result of carcass enrichment. Comparison of the sarcosaprophagous and predatory/parasitic faunas revealed a tighter (and more predictable) linkage between carrion feeders (sarcosaprovores) and their carrion than between carrion feeders and their natural enemies (predators and parasitoids), leading us to conclude that ARF is more representative of surrounding sites with respect to the sarcosaprovore component than to the predatory/parasitic component within the larger carrion-arthropod community.
Autopsy Artifact Created by the Revivant AutoPulse™ Resuscitation Device
Authors: Hart AP , Azar VJ , Hart KR , Stephens BG
Published: November 2004

In certain cases, the evaluation and correct identification of resuscitative artifacts is critical to the correct diagnosis and determination of the cause and manner of death. Resuscitative artifacts can resemble homicidal or accidental injury and thus possibly be misinterpreted. Occasionally, new technologies and/or medical procedures will create original and/or distinctive artifacts. In 2003, the San Francisco Fire Department emergency personnel began field-testing the Revivant AutoPulse™, an automated chest compression device. This device is currently being used in two other counties in the San Francisco Bay Area as well as regions of Florida, Virginia, and Ohio. We present three cases of resuscitative artifact that could be potentially confused with homicidal or accidental injury. These cases illustrate resuscitative artifacts, specifically lateral chest and horizontally oriented upper abdomen cutaneous abrasions created by this automated chest compression device.
Forensic Mitochondrial DNA Analysis of 691 Casework Hairs
Authors: Melton T , Dimick G , Higgins B , Lindstrom L , Nelson K
Published: November 2004

A five year retrospective review of mitochondrial DNA (mtDNA) analysis on 691 casework hairs was carried out. A full or partial mtDNA profile was obtained for ã92% of hairs. With increasing age of the hair, the likelihood of obtaining a full profile decreased, although “mini-primer sets” could often be used to capture a partial profile. With increasing color and diameter of the hair, the likelihood of obtaining a profile increased. Full or partial profiles were obtained on more than 80% of 114 hairs ≤1.0 cm. Mixtures were observed in 8.7% of hairs tested; mixtures increased with the age of the hair and were presumed to be due to exterior surface contamination that could not be sufficiently cleaned prior to extraction, since the overall level of laboratory contamination was low. The frequency of sequence heteroplasmy was 11.4%, and both hot-spot and novel sites were observed. In about one-third of these observations, another sample in the case showed either the same heteroplasmic site or a nucleotide substitution at that site.
A comparison of model performance for six quantitative structure-activity relationship packages that predict acute toxicity to fish
Authors: Moore Dwayne R. J. , Breton Roger L. , MacDonald Drew B.
Published: November 2004

Some regulatory programs rely on quantitative structure-activity relationship (QSAR) models to predict toxic effects to biota. Many currently existing QSAR models can predict the effects of a wide range of substances to biota, particularly aquatic biota. The difficulty for regulatory programs is in choosing the appropriate QSAR model or models for application in their new and existing substances programs. We evaluated model performance of six QSAR modeling packages: Ecological Structure Activity Relationship (ECOSAR), TOPKAT, a Probabilistic Neural Network (PNN), a Computational Neural Network (CNN), the QSAR components of the Assessment Tools for the Evaluation of Risk (ASTER) system, and the Optimized Approach Based on Structural Indices Set (OASIS) system. Using a testing data set of 130 substances that had not been included in the training data sets of the QSAR models under consideration, we compared model predictions for 96-h median lethal concentrations (LC50s) to fathead minnows to the corresponding measured toxicity values available in the AQUIRE database. The testing data set was heavily weighted with neutral organics of low molecular weight and functionality. Many of the testing data set substances also had a nonpolar narcosis mode of action and/or were chlorinated. A variety of statistical measures (correlation coefficient, slope and intercept from a linear regression analysis, mean absolute and squared difference between log prediction and log measured toxicity, and the percentage of predictions within factors of 2, 5, 10, 100, and 1,000 of measured toxicity values) indicated that the PNN model had the best model performance for the full testing data set of 130 substances. The rank order of the remainder of the models depended on the statistical measure employed. TOPKAT also had excellent model performance for substances within its optimum prediction space. Only 37% of the substances in the testing data set, however, fell within this optimum prediction space.
An overview of the use of quantitative structure-activity relationships for ranking and prioritizing large chemical inventories for environmental risk assessments
Authors: Russom Christine L. , Breton Roger L. , Walker John D. , Bradbury Steven P.
Published: November 2004

Ecological risk assessments for chemical stressors are used to establish linkages between likely exposure concentrations and adverse effects to ecological receptors. At times, it is useful to conduct screening risk assessments to assist in prioritizing or ranking chemicals on the basis of potential hazard and exposure assessment parameters. Ranking of large chemical inventories can provide evidence for focusing research and/or cleanup efforts on specific chemicals of concern. Because of financial and time constraints, data gaps exist, and the risk assessor is left with decisions on which models to use to estimate the parameter of concern. In this review, several methods are presented for using quantitative structure-activity relationships (QSARs) in conducting hazard screening or screening-level risk assessments. The ranking methods described include those related to current regulatory issues associated with chemical inventories from Canada, Europe, and the United States and an example of a screening-level risk assessment conducted on chemicals associated with a watershed in the midwest region of the United States.
Quantitative structure-activity relationships for oxidation reactions of organic chemicals in water
Authors: Canonica Silvio , Tratnyek Paul G.
Published: November 2004

Even in the absence of microbiological mediation, oxidation is one of the most important chemical processes contributing to the degradation of organic contaminants in the aquatic environment. The oxidants that are responsible for these reactions include hydroxyl radical, carbonate radical, organic oxyl and peroxyl radicals, peroxides, excited triplet states of organic chromophores, singlet molecular oxygen, ozone, chlorine dioxide, permanganate, and chromate. Some of these oxidants contribute to natural attenuation of organic contaminants, but many are of greater interest because of their role in engineered remediation technologies. Kinetic studies of these processes have lead to numerous quantitative structure-activity relationships (QSARs). Many of these QSARs are simple empirical correlations to common convenient descriptor variables like Hammett constants (σ), half-wave oxidation potentials (E1/2), energies of the highest occupied molecular orbital (EHOMO) or rate constants for other oxidation reactions. However, several environmentally relevant, aqueous-phase oxidation reactions have been described with QSARs based on theoretical models for electron transfer that were developed by Marcus-Hush and Rehm-Weller. This review summarizes many of the reported QSARs for aquatic oxidations of organic compounds with emphasis on the interrelation between traditional empirical models and the potential for future development of QSARs based on theoretical models.
Quantitative structure-activity relationships for predicting soil-sediment sorption coefficients for organic chemicals
Authors: Doucette William J.
Published: November 2004

Sorption coefficients are used to describe the equilibrium distribution of a chemical between a soil or sediment and the aqueous phase that it is in contact with. Although sorption coefficients for a particular organic chemical vary greatly from soil to soil, the observation has been made that sorption generally increases as the organic carbon content of the soil and the hydrophobicity of the chemical increases. This general observation resulted in the acceptance of organic carbon normalized sorption coefficients (Koc) as unique properties or constants of organic chemicals. In turn, Koc values have been estimated by quantitative structure-activity relationships (QSARs) developed by correlation with a variety of physical or chemical properties and structural descriptors related to the hydrophobicity of the chemical such as octanol-water partition coefficients, aqueous solubilities, molecular connectivity indices, molecular weight, molecular surface area, and reverse-phase high-performance liquid chromatography retention times. The selection and application of the most appropriate QSAR for predicting Koc depend on several factors, including the availability of required input, the appropriateness of model to chemical of interest, and the methodology for calculating the necessary topological or structural information. A review of the existing QSARs for predicting Koc and the limitations of using the Koc approach to estimate sorption coefficients will be presented.
Quantitative structure-property relationships for prediction of boiling point, vapor pressure, and melting point
Authors: Dearden John C.
Published: November 2004

Boiling point, vapor pressure, and melting point are important physicochemical properties in the modeling of the distribution and fate of chemicals in the environment. However, such data often are not available, and therefore must be estimated. Over the years, many attempts have been made to calculate boiling points, vapor pressures, and melting points by using quantitative structure-property relationships, and this review examines and discusses the work published in this area, and concentrates particularly on recent studies. A number of software programs are commercially available for the calculation of boiling point, vapor pressure, and melting point, and these have been tested for their predictive ability with a test set of 100 organic chemicals.
Modifications to the fathead minnow (Pimephales promelas) chronic test method to remove mortality due to pathogenic organisms
Authors: Geis Steven W. , Fleming Kari , Mager Amy , Reynolds Lou
Published: November 2004

Whole effluent toxicity testing is used to evaluate the discharge of materials that may be harmful to indigenous aquatic life. Unlike most environmental analyses, receiving water (the water body into which the effluent is discharged) often is used as dilution water in whole effluent toxicity tests to simulate the aquatic environment into which the effluent is introduced. In approximately 26% of whole effluent toxicity tests conducted by Wisconsin (USA) certified labs between 1988 and 1998, a pathogenic effect caused failure of the receiving water controls during the fathead minnow chronic test (i.e., >20% mortality). We performed microbiological work to isolate pathogenic organisms from receiving waters, the fish, and their food. We found pathogenic organisms such as Flexibacter columnaris, Aeromonas hydrophila, and Flavobacter spp. to be ubiquitous and were not able to remove them from the test (e.g., through decontamination of the fish food and carefully following sterility procedures). To eliminate the pathogenic effect, we evaluated manipulations of the sample and the test method including filtering receiving water, irradiating receiving water, using older fish (48 h), using clean test beakers each day of the test, and using smaller test beakers (30 ml) with two fish per beaker. In samples demonstrating the pathogenic effect, most of these manipulations significantly reduced mortality. The use of smaller tests cups was significantly better at reducing the effect than all of the other sample and method manipulations. These results indicate that a simple method modification to the fathead minnow chronic test will improve test reliability when diluting effluents with receiving waters.
Quantitative structure–biodegradation relationships for Ortho-substituted biphenyl compounds oxidized by Methylosinus trichosporium OB3b
Authors: Lindner Angela S. , Whitfield Callie , Chen Ning , Semrau Jeremy D. , Adriaens Peter
Published: November 2004

Methanotrophs, bacteria that thrive in the presence of stable methane and oxygen concentrations, can cometabolically oxidize ortho-substituted biphenyls to yield a variety of hydroxylated products. Despite awareness of the susceptibility of ortho-substituted biphenyls and other aromatic compounds to methanotrophic oxidation, the molecular properties relevant for predicting rates of methanotrophic oxidation are unknown. To this end, we have developed quantitative structure-biodegradation relationships using oxygen uptake activity by the type 2 methanotroph, Methylosinus trichosporium OB3b, expressing the soluble form of methane monooxygenase and in the presence of nine ortho-substituted biphenyls. Multivariate analysis yielded the strongest correlations using the initial slope of the oxygen uptake rate versus substrate concentration curve as the dependent variable. Quantum mechanical descriptors, including the sum of carbon charges on the substituted ring, the charge on the substituted carbon, and the width of compound calculated using computationally derived bond lengths and dihedral angles, correlated more strongly with oxygen uptake activity than did empirically derived electronic descriptors. The resulting models suggest a significant influence of substituent electronic nature and size and the involvement of the substituted carbon site in the oxidation of these compounds by M. trichosporium OB3b.