bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of visual acuity measurements and Purkinje's vessel shadow perception for prediction of postoperative visual acuity in different ophthalmological diseases
Authors: Schulze Stephan , Hoerle Steffen
Published: October 2006

Purpose:  Prediction of postoperative visual acuity (VA) is extremely important to the patient and highly relevant to the surgeon. However, objective evaluation of the macula is frequently impossible in cases such as mature cataract, cataract in high myopia or vitreous haemorrhage. This study compares different preoperative examination techniques used to predict postoperative VA.

Methods:  We retrospectively evaluated the charts of all patients who underwent any of the following procedures at our hospital in 2004: phacoemulsification for mature cataract or cataract in high myopia; vitrectomy for diabetic vitreous haemorrhage; macular pucker, and macular hole. The following methods were evaluated: preoperative distance and reading VA; laser interferential VA; Purkinje's vessel shadow perception, and postoperative distance VA.

Results:  Complete documentation was available for 136 patients (29 mature cataracts, 25 immature cataracts in high myopia, 42 vitreous haemorrhages, 19 macular puckers, 21 macular holes). In cases of preoperative mature cataract, a positive Purkinje's vessel shadow perception predicted a postoperative VA ≥ 20/50 (odds ratio 11.2). In cases of high myopia, interferential VA correlated best with visual outcome (p < 0.05). In macular surgery laser interferential VA predicted postoperative VA to be better and preoperative reading VA predicted it to be worse than it actually turned out after surgery. Laser interferential VA and last known VA prior to vitreous haemorrhage (mean of 20 months previously) correlated best with postoperative VA (p < 0.05) in cases of vitreous haemorrhage. Purkinje's vessel shadow perception – if positive – predicted a postoperative VA ≥ 20/300 in these cases (odds ratio 15.0).

Conclusions:  Postoperative VA after vitrectomy for macular pucker or macular hole and in cases of cataract in high myopia is best predicted by laser interferential VA. Postoperative VA after vitrectomy for diabetic vitreous haemorrhage is best predicted by prehaemorrhage VA or laser interferential VA, especially when prehaemorrhage VA is unknown. Positive Purkinje's vessel shadow perception is an excellent method of predicting postoperative VA ≥ 20/300 in cases of vitreous haemorrhage and VA = 20/50 in mature cataract.
Comparison of two pupillometers in determining pupil size for refractive surgery
Authors: Bootsma Sander , Tahzib Nayyirih , Eggink Fred , De Brabander John , Nuijts Rudy
Published: October 2006

Purpose:  To compare a handheld and a digital pupillometer in determining pupil size in a population of refractive surgery candidates (group 1) and after implantation of an Artisan phakic intraocular lens (PIOL) for correction of myopia (group 2).

Methods:  Pupil size was measured with the Colvard and Procyon pupillometers in 121 eyes in group 1 and 83 eyes in group 2. Pupil sizes measured with the Colvard device were compared with the scotopic, mesopic‐low and mesopic‐high measurements taken with the Procyon pupillometer in both groups. Analysis of comparison between pupil measurements was performed according to methods described by Bland and Altman.

Results:  The mean Colvard scotopic pupil diameter, scotopic, mesopic‐low and mesopic‐high Procyon pupil diameters were 5.86 ± 0.81 mm, 6.42 ± 0.88 mm, 5.55 ± 0.95 mm and 4.21 ± 0.73 mm in group 1 and 5.32 ± 0.67 mm, 6.14 ± 0.81 mm, 5.33 ± 0.78 mm and 4.02 ± 0.55 mm in group 2, respectively. The Colvard diameter compared most favourably with the Procyon mesopic‐low diameter (group 2; p = 0.78).

Conclusions:  Measurements of pupil diameter with the Colvard pupillometer correlated best with measurements taken by the Procyon pupillometer under standardized mesopic‐low light conditions. We believe that digital binocular infrared pupillometry is advantageous for obtaining standardized measurements of pupil size.
B-mode contamination by synchrotron emission from 3-yr Wilkinson Microwave Anisotropy Probe data
Authors: Carretti E. , Bernardi G. , Cortiglioni S.
Published: October 2006

We study the contamination of the B-mode of the cosmic microwave background polarization (CMBP) by Galactic synchrotron in the lowest emission regions of the sky. The 22.8-GHz polarization map of the 3-yr Wilkinson Microwave Anisotropy Probe (WMAP) data release is used to identify and analyse such regions. Two areas are selected with signal-to-noise ratio S/N < 2 and S/N < 3, covering ∼16 and ∼26 per cent fraction of the sky, respectively. The polarization power spectra of these two areas are dominated by the sky signal on large angular scales (multipoles ℓ < 15), while the noise prevails on degree scales. Angular extrapolations show that the synchrotron emission competes with the CMBP B-mode signal for tensor-to-scalar perturbation power ratio T/S= 10−3–10−2 at 70 GHz in the 16 per cent lowest emission sky (S/N < 2 area). These values worsen by a factor ∼5 in the S/N < 3 region. The novelty is that our estimates regard the whole lowest emission regions and outline a contamination better than that of the whole high Galactic latitude sky found by the WMAP team (T/S > 0.3). Such regions allow T/S∼ 10−3 to be measured directly which approximately corresponds to the limit imposed by using a sky coverage of 15 per cent. This opens interesting perspectives on the investigation of the inflationary model space in lowest emission regions.
Using the Distractor Categories of Multiple‐Choice Items to Improve IRT Linking
Authors: Kim Jee‐Seon
Published: October 2006

Simulation and real data studies are used to investigate the value of modeling multiple‐choice distractors on item response theory linking. Using the characteristic curve linking procedure for Bock's (1972) nominal response model presented by Kim and Hanson (2002), all‐category linking (i.e., a linking based on all category characteristic curves of the linking items) is compared against correct‐only (CO) linking (i.e., linking based on the correct category characteristic curves only) using a common‐item nonequivalent groups design. The CO linking is shown to represent an approximation to what occurs when using a traditional correct/incorrect item response model for linking. Results suggest that the number of linking items needed to achieve an equivalent level of linking precision declines substantially when incorporating the distractor categories.
Evaluating DETECT Classification Accuracy and Consistency When Data Display Complex Structure
Authors: Gierl Mark J. , Leighton Jacqueline P. , Tan Xuan
Published: October 2006

DETECT, the acronym for Dimensionality Evaluation To Enumerate Contributing Traits, is an innovative and relatively new nonparametric dimensionality assessment procedure used to identify mutually exclusive, dimensionally homogeneous clusters of items using a genetic algorithm (Zhang & Stout, 1999). Because the clusters of items are mutually exclusive, this procedure is most useful when the data display approximate simple structure. In many testing situations, however, data display a complex multidimensional structure. The purpose of the current study was to evaluate DETECT item classification accuracy and consistency when the data display different degrees of complex structure using both simulated and real data. Three variables were manipulated in the simulation study: The percentage of items displaying complex structure (10%, 30%, and 50%), the correlation between dimensions (.00, .30, .60, .75, and .90), and the sample size (500, 1,000, and 1,500). The results from the simulation study reveal that DETECT can accurately and consistently cluster items according to their true underlying dimension when as many as 30% of the items display complex structure, if the correlation between dimensions is less than or equal to .75 and the sample size is at least 1,000 examinees. If 50% of the items display complex structure, then the correlation between dimensions should be less than or equal to .60 and the sample size be, at least, 1,000 examinees. When the correlation between dimensions is .90, DETECT does not work well with any complex dimensional structure or sample size. Implications for practice and directions for future research are discussed.
Commentary: A Closer Look at Task Analysis: Reactions to Wang, Schnipke, and Witt
Authors: LaDuca Tony
Published: October 2006

In the Spring 2005 issue, Wang, Schnipke, and Witt provided an informative description of the task inventory approach that centered on four functions of job analysis. The discussion included persuasive arguments for making systematic connections between tasks and KSAs. But several other facets of the discussion were much less persuasive. This article offers a critique in the form of four counterarguments: (1) The job analysis method must be appropriate to the nature of the work; (2) The capacity of the task analysis inventory method to describe a complex profession is questionable; (3) Task importance ratings are inherently deficient; and (4) Careful generation of KSAs does not assure systematic item development, which is also necessary in the chain of validity evidence.
A Discussion of Transpiration Cooling Problems through an Analytical Solution of Local Thermal Nonequilibrium Model
Authors: Wang J. H. , Wang H. N.
Published: October 2006

To study transpiration cooling problems, an analytical solution of the local thermal nonequilibrium (LTNE) model with the second or third boundary conditions is presented. This solution is obtained through neglecting the thermal conduction of the fluid coolant in porous media. By the analytical solution, two problems are investigated. At first, the parameters which influence transpiration cooling effects are analyzed, and the analysis indicates that the cooling effects are dominated by coolant mass flow rate, the Biot number at the hot surface of porous plate, and the Biot number in the pores. Second, the error caused by the assumption of the local thermal equilibrium (LTE) model is quantitatively discussed, and the variation trend of the LTE error is analyzed. Based on the analytical solution and the error analysis, a quantitative criterion to choose the LTNE or LTE model is suggested, and the corresponding expression is also given in this paper.
Mechanics of Biomacromolecular Networks Containing Folded Domains
Authors: Jerry Qi H. , Ortiz Christine , Boyce Mary C.
Published: October 2006

The force-extension behavior of single modular biomacromolecules is known to exhibit a characteristic repeating pattern of a nonlinear rise in force with imposed displacement to a peak, followed by a significant force drop upon reaching the peak. This “saw-tooth” pattern is a result of stretch-induced unfolding of modules along the molecular chain and is speculated to play a governing role in the function of biological materials and structures. In this paper, constitutive models for the large strain deformation of networks of modular macromolecules are developed building directly from statistical mechanics based models of the single molecule force-extension behavior. The proposed two-dimensional network model has applicability to biological membrane skeletons and the three-dimensional network model emulates cytoskeletal networks, natural fibers, and soft biological tissues. Simulations of the uniaxial and multiaxial stress-strain behavior of these networks illustrate the macroscopic membrane and solid stretching conditions which activate unfolding in these microstructures. The models simultaneously track the evolution in underlying microstructural features with different macroscopic stretching conditions, including the evolution in molecular orientation and the forces acting on the constituent molecular chains and junctions. The effect of network pretension on the stress-strain behavior and the macroscopic stress and strain conditions which trigger unfolding are presented. The implications of the predicted stress-strain behaviors on a variety of biological materials are discussed.
Modeling Viscoelastic and Viscoplastic Behavior of High Density Polyethylene (HDPE)
Authors: Colak Ozgen U. , Dusunceli Necmi
Published: October 2006

The viscoelastic and viscoplastic behaviors of high density polyethylene (HDPE) under uniaxial monotonic and cyclic loading are modeled using the modified viscoplasticity theory based on overstress (VBO). The viscoelastic modeling capabilities of the modified VBO are investigated by simulating the behavior of semicrystalline HDPE under uniaxial compression tests at different strain rates. In addition, the effects of the modification (introducing the variable “C” into an elastic strain rate equation) on VBO that has been made to construct the change in the elastic stiffness while loading and unloading are investigated. During first loading and unloading, the modification in the elastic strain rate equation improves the unloading behavior. To investigate how the variable “C” that is introduced in the elastic strain rate equation evolves during reloading, the cyclic behavior of HDPE is modeled. For a complete viscoelastic and viscoplastic behavior, the relaxation and creep behaviors of HDPE are simulated as well in addition to stress and strain rate dependency. The influences of the strain (stress) levels where the relaxation (creep) experiments are performed are investigated. The simulation results are compared with the experimental data obtained by Zhang and Moore (1997, Polym. Eng. Sci., 37, pp. 404–413). A good match between experimental and simulation results are observed.
Creep Rupture of Multidirectional Polymer Composite Laminates — Influence of Time-Dependent Damage
Authors: Birur A. , Gupta A. , Raghavan J.
Published: October 2006

Evolution of various damage modes with time, in multidirectional laminates of a polymer composite (Hexcel F263-7/T300) subjected to a constant load, was experimentally studied and correlated to experimental creep rupture results to understand the influence of the former on the latter. Influence of various parameters, such as stress, temperature, thickness of inner plies, and outer-ply constraint, on damage evolution was evaluated. Observed damages include transverse (also referred in the literature as matrix cracks) cracking due to in-plane stresses, vertical cracking due to out-of-plane normal stress, delamination due to interlaminar stresses, splitting, and fiber fracture. The sequence of evolution of these damages varied with laminate stacking sequence, stress, and temperature. These damages significantly influenced one another and the creep rupture time.
Direct Demonstration of an Adaptive Constraint
Authors: Miller Stephen P. , Lunzer Mark , Dean Antony M.
Published: October 2006

The role of constraint in adaptive evolution is an open question. Directed evolution of an engineered β-isopropylmalate dehydrogenase (IMDH), with coenzyme specificity switched from nicotinamide adenine dinucleotide (NAD) to nicotinamide adenine dinucleotide phosphate (NADP), always produces mutants with lower affinities for NADP. This result is the correlated response to selection for relief from inhibition by NADPH (the reduced form of NADP) expected of an adaptive landscape subject to three enzymatic constraints: an upper limit to the rate of maximum turnover (
k
cat
), a correlation in NADP and NADPH affinities, and a trade-off between NAD and NADP usage. Two additional constraints, high intracellular NADPH abundance and the cost of compensatory protein synthesis, have ensured the conserved use of NAD by IMDH throughout evolution. Our results show that selective mechanisms and evolutionary constraints are to be understood in terms of underlying adaptive landscapes.
PREPARATION AND STORAGE OF ENTANGLED STATES FOR MULTIPLE TRAPPED IONS IN THERMAL MOTION
Authors: YANG WEN-XING , ZHANG SU-ZHEN
Published: October 2006

We present an alternative scheme to prepare entangled states of multiple trapped ions in thermal motion. In this scheme the vibrational degrees of freedom are only regarded as intermediate states and the ions exchange energy via the mediation of the vibration of the vibrational mode in coupling processes. The scheme is insensitive to both the initial vibrational state and heating if the system remains in the Lamb–Dicke regime. Since the effective Rabi frequency has a small dependence on the vibrational quantum number, the heating will have no direct effect on the internal state evolution. The scheme can also be used for the storage of entangled states.
MAGNETIC INTERACTION OF THE COMPOSITE MIXTURES Nd-Fe-B/Sm2Co17
Authors: BAI SHUXIN , LI SHUN , ZHANG HONG , CHEN KE , CAI HONGNIAN
Published: October 2006

Hybrid-bonded isotropic Nd-Fe-B /anisotropic Sm 2 Co 17 magnets with different mass fraction of Sm 2 Co 17 powders had been analyzed with the aid of magnetization and demagnetization curves. It was found that the Henkel plot of magnet with 10 wt.% Sm 2 Co 17 lies above the Wohlfarth line at low magnetic field but goes down slowly and then lies below the Wohlfarth line at high magnetic field. This shows magnetizing interaction at first and demagnetizing interaction at last, and presents an s-shaped behavior that has been seen frequently in nanocomposite exchange-coupled magnets. The demagnetization curve of 10 wt.% Sm 2 Co 17 content hybrid-bonded magnet exhibits a magnetically single phase behavior which has also been seen frequently in nanocomposite exchange-coupled magnets, indicating complex magnetic interaction between these two magnetic particles. As a result, a small increase in remanence and energy product are observed in hybrid-bonded Nd-Fe-B/Sm 2 Co 17 magnets with 10% mass fraction of Sm 2 Co 17.
USING THEORY OF MIND METHODS TO INVESTIGATE EMPATHIC ENGAGEMENT WITH SYNTHETIC CHARACTERS
Authors: HALL LYNNE , WOODS SARAH , AYLETT RUTH , PAIVA ANA
Published: October 2006

This paper is concerned with the simulation of human-likess capabilities in synthetic characters within the domain of Personal and Social Education. Our aim was to achieve socially meaningful and engaging interactions with children in the 8–12 age group to enable an exploration of bullying and coping strategies. We consider the engagement between the interacting partners, focusing particularly on the affective and empathic aspects of this relationship. We have used Theory of Mind methods to enable us to evaluate children's understanding of social scenarios and the thinking of others. The results from this 345 children study highlight that children are able to recognize and interpret affect in synthetic characters and are empathically engaged with the characters in the scenarios.
Multiplicity of expression of FXYD proteins in mammalian cells: dynamic exchange of phospholemman and γ-subunit in response to stress
Authors: Arystarkhova Elena , Donnet Claudia , Muñoz-Matta Ana , Specht Susan C. , Sweadner Kathleen J.
Published: October 2006

Functional properties of Na-K-ATPase can be modified by association with FXYD proteins, expressed in a tissue-specific manner. Here we show that expression of FXYDs in cell lines does not necessarily parallel the expression pattern of FXYDs in the tissue(s) from which the cells originate. While being expressed only in lacis cells in the juxtaglomerular apparatus and in blood vessels in kidney, FXYD1 was abundant in renal cell lines of proximal tubule origin (NRK-52E, LLC-PK1, and OK cells). Authenticity of FXYD1 as a part of Na-K-ATPase in NRK-52E cells was demonstrated by co-purification, co-immunoprecipitation, and co-localization. Induction of FXYD2 by hypertonicity (500 mosmol/kgH2O with NaCl for 48 h or adaptation to 700 mosmol/kgH2O) correlated with downregulation of FXYD1 at mRNA and protein levels. The response to hypertonicity was influenced by serum factors and entailed, first, dephosphorylation of FXYD1 at Ser68 (1–5 h) and, second, induction of FXYD2a and a decrease in FXYD1 with longer exposure. FXYD1 was completely replaced with FXYD2a in cells adapted to 700 mosmol/kgH2O and showed a significantly decreased sodium affinity. Thus dephosphorylation of FXYD1 followed by exchange of regulatory subunits is utilized to make a smooth transition of properties of Na-K-ATPase. We also observed expression of mRNA for multiple FXYDs in various cell lines. The expression was dynamic and responsive to physiological stimuli. Moreover, we demonstrated expression of FXYD5 protein in HEK-293 and HeLa cells. The data imply that FXYDs are obligatory rather than auxiliary components of Na-K-ATPase, and their interchangeability underlies responses of Na-K-ATPase to cellular stress.
Estimating whole body intermuscular adipose tissue from single cross-sectional magnetic resonance images
Authors: Ruan Xiang Yan , Gallagher Dympna , Harris Tamara , Albu Jeanine , Heymsfield Steven , Kuznia Patrick , Heshka Stanley
Published: October 2006

Intermuscular adipose tissue (IMAT), a novel fat depot linked with metabolic abnormalities, has been measured by whole body MRI. The cross-sectional slice location with the strongest relation to total body IMAT volume has not been established. The aim was to determine the predictive value of each slice location and which slice locations provide the best estimates of whole body IMAT. MRI quantified total adipose tissue of which IMAT, defined as adipose tissue visible within the boundary of the muscle fascia, is a subcomponent. Single-slice IMAT areas were calculated for the calf, thigh, buttock, waist, shoulders, upper arm, and forearm locations in a sample of healthy adult women, African-American [ n = 39; body mass index (BMI) 28.5 ± 5.4 kg/m2; 41.8 ± 14.8 yr], Asian ( n = 21; BMI 21.6 ± 3.2 kg/m2; 40.9 ± 16.3 yr), and Caucasian ( n = 43; BMI 25.6 ± 5.3 kg/m2; 43.2 ± 15.3 yr), and Caucasian men ( n = 39; BMI 27.1 ± 3.8 kg/m2; 45.2 ± 14.6 yr) and used to estimate total IMAT groups using multiple-regression equations. Midthigh was the best, or near best, single predictor in all groups with adjusted R2 ranging from 0.49 to 0.84. Adding a second and third slice further increased R2 and reduced the error of the estimate. Menopausal status and degree of obesity did not affect the location of the best single slice. The contributions of other slice locations varied by sex and race, but additional slices improved predictions. For group studies, it may be more cost-effective to estimate IMAT based on one or more slices than to acquire and segment for each subject the numerous images necessary to quantify whole body IMAT.
Reconciling the Origins of Africa, India and Madagascar with Vertebrate Dispersal Scenarios
Authors: Masters J.C. , de Wit M.J. , Asher R.J.
Published: October 2006

Africa, India and Madagascar were once part of the supercontinent of Gondwana. This land mass began to fragment approx. 170 million years ago, and by 83 million years, all of the major components we recognize today were separated by tracts of water. Madagascar’s fossil record and estimates of the timing of the extant vertebrate radiations in Madagascar are not easily reconciled with this history of fragmentation. Fossil faunas that lived prior to approx. 65 million years had a cosmopolitan flavour, but this was lost after the Cretaceous-Tertiary boundary. Phylogenetic reconstructions of most extant Malagasy vertebrate radiations indicate divergence times that postdate the End-Cretaceous (lemurs, tenrecs, cichlid fish) and even the Early Miocene (chameleons, carnivores, rodents). Most biogeographic explanations of these groups rely, therefore, on Simpson’s model of sweepstakes dispersal (see also cover figure), but there are significant problems in applying the model to migrations from Africa to Madagascar, although its application is not so intractable between India and Madagascar. Alternative migration routes for consideration lie: (1) along the suite of fracture zones between Antarctica and Africa/Madagascar (known as the Antarctic-Africa Corridor), which may have been exposed episodically above sea level; (2) along a series of submerged basaltic ridges/plateaus with known or suspected continental crust between Antarctica and Africa/Madagascar/India flanking the Antarctic-Africa Corridor (e.g. the Madagascar Ridge, Mozambique Ridge, Conrad Plateau, Gunnerus Ridge); (3) between Africa and Madagascar along the Davie Ridge (parts of which are known to have been exposed episodically above sea level); (4) along the Deccan hotspot corridor between India and greater Africa.
Well-Being Therapy in School Settings: A Pilot Study
Authors: Ruini Chiara , Belaise Carlotta , Brombin Chiara , Caffo Ernesto , Fava Giovanni A.
Published: October 2006

Background: There is increasing interest in the psychobiological mechanisms of resilience and psychological well-being. It is conceivable that activation of such mechanisms in the school setting may entail long-term benefits, both in terms of the developmental process and of prevention of distress. This study wants to apply and test the efficacy of a school-based intervention protocol derived from well-being therapy (WBT) compared to cognitive-behavioral strategies. Methods: School interventions were performed in a population of 111 students randomly assigned to: (a) a protocol using theories and techniques derived from cognitive-behavioral therapy; (b) a protocol derived from WBT. Assessment before and after interventions was performed using two self-rating scales: Kellner’s Symptom Questionnaire and Ryff’s Psychological Well-Being Scales. Results: Both school-based interventions resulted in a comparable improvement in symptoms and psychological well-being. Conclusions: This new well-being-enhancing strategy could play an important role in the prevention of psychological distress in school settings and in promoting optimal human functioning among children.
Clinical Epidemiology of Eating Disorders: Results from the Sesto Fiorentino Study
Authors: Faravelli C. , Ravaldi C. , Truglia E. , Zucchi T. , Cosci F. , Ricca V.
Published: October 2006

Background: It is speculated that clinical samples do not fully reflect the characteristics of eating disorders (EDs) as they are in the general population, especially in their lowest range of severity. The present article reports the prevalence of EDs in a community sample aged >14 years, their clinical and psychopathological features, and their course and outcome on naturalistic grounds. Methods: The Sesto Fiorentino Study is a three-phase community-based survey where 2,355 out of 2,500 people representative of the population aged >14 years living in Sesto Fiorentino were evaluated by their own general practitioner using the Mini International Neuropsychiatric Interview plus six additional questions. All those who had positive results plus a probability sample of the non-cases were re-interviewed by psychiatrists using the Florence Psychiatric Interview. The subjects who reported ED symptoms were subsequently administered the Eating Disorder Examination (12th edition). Results: Overall, the lifetime prevalence of EDs was 1.21%. More precisely, 0.42% had anorexia nervosa, 0.32% bulimia nervosa, 0.32% binge eating disorder and 0.32% eating disorder not otherwise specified. All the subjects suffering from an ED fulfilled diagnostic criteria for at least another DSM-IV axis I psychiatric disorder. At the moment of the interview, conducted a few years (average 7 years) after the onset of the disorder, 50% had fully recovered from EDs, 26.9% were currently affected by an ED, 23.1% showed a persistent body image disturbance and/or the presence of compensatory behaviours. Conclusions: Community surveys conducted by clinicians may provide useful additional information on the psychopathological features, natural course and outcome of these disorders on naturalistic grounds.
Influence of Platelet-Rich Plasma on Osteogenic Differentiation of Mesenchymal Stem Cells and Ectopic Bone Formation in Calcium Phosphate Ceramics
Authors: Kasten Philip , Vogel Julia , Luginbühl Reto , Niemeyer Philipp , Weiss Stefan , Schneider Sven , Kramer Martin , Leo Albrecht , Richter Wiltrud
Published: October 2006

Platelet-rich plasma (PRP) contains a mixture of growth factors that play an important role in wound and fracture healing. While PRP enhanced bone formation by autogenous cancellous bone grafts, its influence in combination with different bone substitutes remained unknown. This study evaluated the effect of PRP on osteogenic differentiation and ectopic bone formation of human mesenchymal stem cells (MSC) in distinct resorbable calcium phosphate ceramics. Calcium-deficient hydroxyapatite (CDHA) blocks with a large specific surface area (48 m2/g) and β-tricalcium phosphate (β-TCP) with a low specific surface area (<0.5 m2/g) were loaded with 2 × 105 bone marrow-derived MSC. Half of the specimens were treated with 5-fold concentrated PRP. Biocomposites were implanted subcutaneously into SCID mice or kept under osteogenic culture conditions for 2 weeks before implantation. The addition of PRP increased the specific alkaline phosphatase (ALP) activity (p = 0.012) in undifferentiated MSC/CDHA composites but not in MSC/β-TCP composites. Osteogenic preinduction was ineffective for CDHA and reduced ALP activity of β-TCP composites significantly at explantation. Ectopic bone formation was stronger in MSC/CDHA (7/32) compared to MSC/β-TCP (2/30) composites, but no influence of PRP was evident. In conclusion, the effect of PRP depended on the type of ceramic and the differentiation status of the MSC, and enhanced ALP activity of MSC on the high surface scaffold CDHA only, but PRP did not improve osteogenesis in our setting.
Culture of Human Skeletal Muscle Myoblasts: Timing Appearance and Localization of Dystrophin-Glycoprotein Complex and Vinculin-Talin-Integrin Complex
Authors: Trimarchi F. , Favaloro A. , Fulle S. , Magaudda L. , Puglielli C. , Di Mauro D.
Published: October 2006

The dystrophin-glycoprotein complex together with the vinculin-talin-integrin complex plays an important role in muscle function; in fact the mutations of their elements lead to diverse forms of muscular dystrophies. The relationship between the elements of dystrophin-glycoprotein complex and vinculin-talin-integrin and the time course of their formation are still not known in detail. In order to better understand this relationship we studied their expression during development in normal human skeletal muscle culture. Using a standardized muscle cell culture procedure, this study was performed to analyze the timing, appearance and the localization of some proteins of the dystrophin-glycoprotein complex and vinculin-talin-integrin complex during cellular proliferation (myoblast) and differentiation (4, 7, 15 and 21 days). The indirect immunofluorescence technique was used and cells were examined using a Meta Zeiss LSM510 confocal laser scanning inverted microscope. We examined the progressive appearance of the following proteins: α, β, γ, δ-sarcoglycans, β-dystroglycan, dystrophin, talin, vinculin and integrin isoform α7/β1. Immunofluorescence of these proteins, in satellite cells entering myogenic differentiation, revealed different patterns of localization depending on the time of culture. We showed that nondifferentiated cultures of human myoblasts expressed a perinuclear distribution of all proteins tested. During myoblast differentiation into myotubes (4 days) immunofluorescence gradually increased and was located in the whole cytoplasm. Subsequently, at day 7, a strong and homogeneous cytoplasmic labelling of all proteins was seen. At 15 days the distribution of the proteins was on the membrane. At this time some myotubes displayed a significant degree of precostameric banding pattern. As fusion proceeded at 21 days, the cytodistribution progressively changed and appeared along fibrillar longitudinal structures, and myotubes showed a clear periodic distribution (costameres). In conclusion, in normal human muscle cultures DGC and vinculin-talin-integrin proteins are first localized in the perinuclear region, then they diffuse in the cytoplasm and finally form at the plasma membrane into typical rib-like structures that are sarcolemma-associated.
Proposal for a New Clinicoradiological Classification of Type I Split-Cord Malformations: A Prospective Study of 25 Cases
Authors: Gupta Deepak Kumar , Mahapatra Ashok Kumar
Published: October 2006

Background and Methods: Split-cord malformations (SCMs) are rare malformations of the spinal cord. A new classification is proposed based on intraoperative findings in 25 cases of type I SCMs (with bony spur). Patients’ demographic profile, radiological and surgical details, complications and outcome were noted. Findings: All patients had type I SCMs. The mean age of the patients was 6.2 years (female:male ratio 1.2:1). Asymmetric lower-limb and sphincter weakness were present in 17/25 (68%) and 5/25 (20%) cases, respectively. Of the symptomatic cases, 29.4% (5/17) showed improvement in motor power and sensory improvement was recorded in 33.3% (4/12) of patients while 40% (2/5) regained continence. No patient in the asymptomatic group (0/8) showed postoperative neurological deterioration. A new subclassification of type I SCM is proposed based on the location of the bony spur responsible for the split, which can affect surgical dissection and outcome. Conclusions: In SCM patients, the risk of developing neurological deficits increases with age, hence all SCM patients should undergo prophylactic surgery, even if they are asymptomatic. Our new classification is easy to use and takes into account intraoperative findings that may affect surgical outcome.
Atypical Presentations in Chiari II Malformation
Authors: Rath G.P. , Bithal P.K. , Chaturvedi A.
Published: October 2006

Myelomeningocele with Chiari II malformation and hydrocephalus is a common association seen in infants with a congenital failure of neurulation. Here we report two cases of such an association presenting with different sets of problems. The first patient presented with severe inspiratory stridor due to bilateral abductor vocal cord paralysis, which was relieved completely within 24 h of definitive surgery. The second patient experienced intraoperative cardiac arrest. Definitive surgery was followed after successful cardiopulmonary resuscitation. The cause of the perioperative sequence of events in both cases is attributed to the associated pathologies of Chiari II malformation.
Iatrogenic Intraspinal Epidermoid Tumor: Case Report
Authors: Jeong In-Ho , Lee Jung-Kil , Moon Kyung-Sub , Kwak Hyoung-Jun , Joo Sung-Pil , Kim Tae-Sun , Kim Jae-Hyoo , Kim Soo-Han
Published: October 2006

Iatrogenic spinal epidermoid tumors are extremely rare and may be caused by skin fragments which were implanted in the spine as a result of a trauma or lumbar puncture. Due to the time lag between the lumbar puncture and the development of a symptomatic tumor, this relationship is often overlooked and can cause a delay in the proper diagnosis. Here, we report a rare case of an intraspinal epidermoid tumor, which developed 7 years after a lumbar puncture in a 12-year-old boy, who presented with back pain and radiating pain to the posterior of both thighs. A total excision of the tumor via L3–L4 hemilaminectomy yielded a good functional recovery.
Diabetes Mellitus following Paediatric Renal Transplantation: A Single Centre Experience
Authors: Sukthankar S.A. , Lewis M.A. , Webb N.J.A. , Plant N.D. , Price D.A. , Hall C.M.
Published: October 2006

Background/Aims: Post-transplant diabetes mellitus (PTDM) has a variably reported incidence of 4–41% among adults and children. We describe our recent experience of four children with PTDM in a paediatric renal transplantation centre. Methods: We undertook a retrospective analysis of the glycaemic status of all paediatric patients undergoing renal transplantation at our centre in the 2-year study period. The clinical features and investigations of those who developed PTDM were further reviewed. Results: Five episodes of PTDM occurred in 4/32 children. There was a variable onset and a wide range of symptoms. Investigations revealed a combination of insulinopenia with peripheral insulin resistance. Insulin therapy was required for variable durations with resolution of PTDM in four episodes. PTDM did not adversely affect the renal graft function. Conclusion: PTDM requires increased awareness among paediatric nephrologists and endocrinologists for early recognition and prompt effective intervention.
Interpersonal Problem Areas and Onset of Panic Disorder
Authors: Scocco P. , Barbieri I. , Frank E.
Published: October 2006

Background: Numerous studies indicate that stressful life events are key precipitants of psychological disturbances. Severe stress often precedes the onset or exacerbation of illness in vulnerable individuals and may be of primary importance in the genesis of some mental disorders. Several authors have suggested that major life events play a role in the development of panic-related symptoms. The aim of this study was to examine the presence of stressful life events, in particular events focused in the interpersonal psychotherapy problem areas (grief, role disputes, role transitions, interpersonal deficits), in patients suffering from panic disorder. Methods: We interviewed 55 patients suffering from panic disorder, with or without agoraphobia, in accordance with the diagnostic criteria specified in MINI PLUS. The panic attack profile was evaluated with the Panic Attack and Anticipatory Anxiety Scale. We assessed the ability to adapt to and derive satisfaction from the social environment with the Social Adjustment Scale Self Report and interpersonal problems with Interpersonal Questionnaire. Results: Using the Interpersonal Questionnaire we found that all subjects had had relevant interpersonal problems in the year preceding the onset of PD: 92.7% had experienced a role transition, 85.5% interpersonal deficits, 74.5% a role dispute and 38.2% had suffered the loss of a relative or significant other. These results were confirmed by Paykel’s scale, on which the whole sample reported a high frequency of life events in the 6 months before onset of illness. These preliminary data suggest a rationale for the therapeutic strategies of interpersonal psychotherapy in individuals with panic disorder.
Relationship Patterns in Alexithymia: A Study Using the Core Conflictual Relationship Theme Method
Authors: Vanheule Stijn , Desmet Mattias , Rosseel Yves , Verhaeghe Paul , Meganck Reitske
Published: October 2006

Background: Alexithymia is a disturbance in regulating affective states. Clinical observations suggest that alexithymic patients relate to others in a specific way. This paper explores whether specific relationship or transference patterns are typical of alexithymia. Sampling and Methods: Relationship patterns were assessed by means of the Core Conflictual Relationship Theme method, standard categories version. This method examines transference patterns and was applied to clinical interview data collected from a sample (n = 31) of mental health outpatients. Alexithymia was assessed by means of a score on the 20-item Toronto Alexithymia Scale corrected for the degree of depression (measured by the Beck Depression Inventory-II). Data were analysed by means of the leaps and bounds regression algorithm for selecting optimal subsets of indicators and by bootstrapping to determine 95% confidence intervals. Results: First, we observed that alexithymia can be meaningfully explained by typical wishes, typical subjective perceptions of how others respond and one’s own typical responses to others. This result indicates that the more marked a patient’s alexithymic traits are, the more probable it is that specific transference themes come to the fore. Second, a set of three core indicators of trait alexithymia was mapped: little concern about being good to others, a strong perception of others as cooperative, and weak levels of reacting to others and to conflict by means of somatic symptoms. Conclusion: Alexithymia is related to a double interpersonal indifference: not much is expected from others, nor is there a personal urge to fulfill the expectations of others. Moreover, in alexithymia somatic symptoms proved to be non-reactive to interpersonal situations. Implications for diagnosis and treatment are highlighted. Limitations of our study are that alexithymia was only assessed with a self-report measure and that conclusions are based only upon data from a heterogeneous mental health sample.
An Oral Adsorbent, AST-120, Suppresses Oxidative Stress in Uremic Rats
Authors: Nakagawa Naoki , Hasebe Naoyuki , Sumitomo Kazuhiro , Fujino Takayuki , Fukuzawa Jun , Hirayama Tomoya , Kikuchi Kenjiro
Published: October 2006

Background: The production of reactive oxygen species (ROS) has been suggested to play an important role in the progression of chronic kidney disease (CKD). An oral adsorbent, AST-120, removes uremic toxins such as indoxyl sulfate (IS) and delays the progression of CKD, but the effect on ROS production is unknown. The present study aimed to determine whether AST-120 reduces oxidative stress in uremic rat kidneys using markers of ROS production such as acrolein and 8-hydroxy-2′-deoxyguanosine (8-OHdG). Methods: Daily administration of AST-120 was started 6 weeks after 5/6 nephrectomy and continued for 18 weeks. The changes in metabolic data, serum and urine IS levels, urinary excretion of markers of oxidative stress, and renal histological findings were investigated in uremic rats with or without AST-120 treatment. Results: In parallel with the increase in serum and urine IS, the serum creatinine, urinary protein and acrolein levels started to increase at 6 weeks, but urinary 8-OHdG remained unchanged and significantly increased at 18 weeks in uremic rats. AST-120 markedly and significantly attenuated increases in uremic toxins and oxidative stress levels as well as the histological changes in glomerular sclerosis, interstitial fibrosis, and the tubular staining of 8-OHdG. Conclusion: AST-120 suppressed the progression of CKD, at least in part, via attenuation of oxidative stress induced by uremic toxin.
Short-Term Synaptic Plasticity Can Enhance Weak Signal Detectability in Nonrenewal Spike Trains
Authors: Lüdtke Niklas , Nelson Mark E.
Published: October 2006

We study the encoding of weak signals in spike trains with interspike interval (ISI) correlations and the signals' subsequent detection in sensory neurons. Motivated by the observation of negative ISI correlations in auditory and electrosensory afferents, we assess the theoretical performance limits of an individual detector neuron receiving a weak signal distributed across multiple afferent inputs. We assess the functional role of ISI correlations in the detection process using statistical detection theory and derive two sequential likelihood ratio detector models: one for afferents with renewal statistics; the other for afferents with negatively correlated ISIs. We suggest a mechanism that might enable sensory neurons to implicitly compute conditional probabilities of presynaptic spikes by means of short-term synaptic plasticity. We demonstrate how this mechanism can enhance a postsynaptic neuron's sensitivity to weak signals by exploiting the correlation structure of the input spike trains. Our model not only captures fundamental aspects of early electrosensory signal processing in weakly electric fish, but may also bear relevance to the mammalian auditory system and other sensory modalities.
Learning Tetris Using the Noisy Cross-Entropy Method
Authors: Szita István , Lörincz András
Published: October 2006

The cross-entropy method is an efficient and general optimization algorithm. However, its applicability in reinforcement learning (RL) seems to be limited because it often converges to suboptimal policies. We apply noise for preventing early convergence of the cross-entropy method, using Tetris, a computer game, for demonstration. The resulting policy outperforms previous RL algorithms by almost two orders of magnitude.
Event-Driven Simulation Scheme for Spiking Neural Networks Using Lookup Tables to Characterize Neuronal Dynamics
Authors: Ros Eduardo , Carrillo Richard , Ortigosa Eva M. , Barbour Boris , Agís Rodrigo
Published: October 2006

Nearly all neuronal information processing and interneuronal communication in the brain involves action potentials, or spikes, which drive the short-term synaptic dynamics of neurons, but also their long-term dynamics, via synaptic plasticity. In many brain structures, action potential activity is considered to be sparse. This sparseness of activity has been exploited to reduce the computational cost of large-scale network simulations, through the development of event-driven simulation schemes. However, existing event-driven simulations schemes use extremely simplified neuronal models. Here, we implement and evaluate critically an event-driven algorithm (ED-LUT) that uses precalculated look-up tables to characterize synaptic and neuronal dynamics. This approach enables the use of more complex (and realistic) neuronal models or data in representing the neurons, while retaining the advantage of high-speed simulation. We demonstrate the method's application for neurons containing exponential synaptic conductances, thereby implementing shunting inhibition, a phenomenon that is critical to cellular computation. We also introduce an improved two-stage event-queue algorithm, which allows the simulations to scale efficiently to highly connected networks with arbitrary propagation delays. Finally, the scheme readily accommodates implementation of synaptic plasticity mechanisms that depend on spike timing, enabling future simulations to explore issues of long-term learning and adaptation in large-scale networks.
Bifurcation Analysis of Jansen's Neural Mass Model
Authors: Grimbert François , Faugeras Olivier
Published: October 2006

We present a mathematical model of a neural mass developed by a number of people, including Lopes da Silva and Jansen. This model features three interacting populations of cortical neurons and is described by a six-dimensional nonlinear dynamical system. We address some aspects of its behavior through a bifurcation analysis with respect to the input parameter of the system. This leads to a compact description of the oscillatory behaviors observed in Jansen and Rit (1995) (alpha activity) and Wendling, Bellanger, Bartolomei, and Chauvel (2000) (spike-like epileptic activity). In the case of small or slow variation of the input, the model can even be described as a binary unit. Again using the bifurcation framework, we discuss the influence of other parameters of the system on the behavior of the neural mass model.
Desperately Seeking Legitimacy: Organizational Identity and Emerging Industries
Authors: Clegg Stewart R. , Rhodes Carl , Kornberger Martin
Published: October 2006

In this article we examine the process of organizational identity formation in emerging industries. We argue that organizational identity is best understood in terms of the relationship between temporal difference (i.e. the performance of a stable identity over time) and spatial difference (i.e. by locating organizational identity in relation to other firms, both similar and different). It is the relationship between these two forms of difference that enables the construction of a legitimate sense of organizational identity. Our discussion is illustrated using empirical material from a study of the emerging industry of business coaching in Australia.