bluuebunny/crossref_metadata_2025 huggingface dataset:
Geostatistics
Authors: Wackernagel Hans
Published: October 2006

Geostatistics is an application of the theory of random functions to spatially distributed data. The methods, initially proposed by Matheron in mining and petroleum exploration, found their way back to mainstream statistics more than a decade ago. The geostatistical methodology can be subdivided into linear and multivariate geostatistics, nonstationary geostatistics, nonlinear geostatistics, geostatistical simulation.
U

‐ and

V

‐Statistics
Authors: Shieh Grace S.
Published: October 2006

This article reviews the development of
U
‐ and
V
‐statistics from mid‐1990s to 2001. Three categories of new results are reviewed: (1) asymptotic behavior of
U
‐ and
U
‐related statistics, (2) asymptotic distribution theory (including asymptotic distribution, Berry‐Esseen theorem, and Edgeworth expansion), and (3) a new subclass,
U
‐statistics* with a kernel of indeterminate degeneracy.
Discrete Multivariate Distributions
Authors: Balakrishnan N.
Published: October 2006

In this article, we present a concise review of developments on discrete multivariate distributions. We first present some basic definitions and notations. Then, we present several important discrete multivariate distributions and list their significant properties and characteristics.
Banking, Statistics in
Authors: Hand David J.
Published: October 2006

Mathematical models in the investment banking and financial markets sectors have been the focus of concentrated research effort for several decades, but the application of statistical methods is a relatively new development. In contrast, in retail banking, statistical models have been applied for over 40 years, though of late their level of sophistication and complexity has increased dramatically. Both developments are a result of increased computer power. A large range of types of statistical tools are being applied, but especially tools concerned with predicting default risk at various levels. Given the increased competition, the current harsh economic climate, and toughening legislative environment, it seems likely that the demand for objective statistical methods will become even greater in the future.
Human Capital
Authors: Dagum Camilo
Published: October 2006

This entry deals with the concept of human capital and its monetary value estimation. The basic assumptions and limitations of the traditional prospective (actuarial) and retrospective (cost of production) methods are discussed. A more efficient estimation procedure, the latent variable‐actuarial method, is presented and illustrated using information from the 1983 US Federal Reserve Board sample survey of income and wealth distribution. The main results obtained are the standardized value of each household HC latent variable, the average HC by age of the household heads, the average national HC, the monetary value of each household HC, and its size distribution.
Stochastic Resonance
Authors: Bulsara Adi R.
Published: October 2006

Noise is usually considered a nuisance or a laboratory curiosity, better avoided, in most practical applications. However, certain nonlinear dynamic systems in nature (the most ubiquitous of these being, of course, the central nervous system) appear to utilize the background noise as an aid to the analysis of low‐intensity signals embedded in the noise floor. A phenomenon known as stochastic resonance (SR) has been studied in the context of this amplification of weak signals in a noise background; the effect is only one of a plethora of diversified behavior that is displayed by nonlinear dynamic systems in the presence of noise, and can actually lead to an energy transfer from the noise floor to the signal feature (in the response), under the appropriate operating conditions.
Editing Statistical Data
Authors: Naus Joseph
Published: October 2006

There are several statistical and data‐processing techniques that exist in the literature to mnitor data and also to detect and correct errors in them. This area of Statistics has developed its own extensive terminology. In this entry, the terminology and the important techniques used in data editing and imputation are described.
Epidemiological Statistics—II
Authors: McNeil Don
Published: October 2006

Epidemiological studies use statistical methods to understand the factors that cause, reduce, and prevent diseases in human populations. These studies estimate the parameters in a target population based on representative samples, and can be qualitative or quantitative, descriptive or comparative, and observational or experimental. Parameters of interest include levels of disease and associations between risk factors and disease outcomes. Concept maps are useful for showing causal paths between risk factors, disease outcomes, and intervening variables (confounders) that could distort the association. The statistical methods can be classified by the type and role of the data, and are subject to both inaccuracy or lack of statistical power (due to sampling variability) and bias (due to faulty measurement, differential selection of subjects, or confounding). Matching of subjects can improve accuracy. Mantel–Haenszel methods can reduce confounding bias. Meta‐analysis is used to combine results from different studies. Statistical models include linear, logistic, and Poisson regression, and the proportional hazards model for handling censored data.
Income Distribution Models
Authors: Dagum Camilo
Published: October 2006

Since Pareto specified his Type I model in 1895, scores of income distribution (ID) models have been proposed. Many of them follow Edgeworth's approach, starting with a probability function and a transformation of its random variable, to derive a positive asymmetric distribution as an ID model. Some of them are supported by a realistic scientific foundation, others are the outcome of a formal analogy, and the remainder are only ad hoc specifications. Almost all of these models are organized here in three generating systems, and their respective foundations are outlined. We introduce a set of seven basic properties to be fulfilled by a probability distribution for consideration as an ID model. Their main purpose is to guide researchers in the evaluation and choice of an appropriate and robust model to describe observed IDs in different epochs and countries in different states of socioeconomic development, and according to several socioeconomic attributes of the observed populations of economic units.
Markov Networks
Authors: Castillo Enrique , Hadi Ali S.
Published: October 2006

Many practical applications require the specification of the joint probability density (JPD) of a large set of random variables. This task can be very difficult in practice. Bayesian and Markov networks are two graphically based models that make the specification of the JPD and the propagation of uncertainty simple and efficient because they exploit the conditional independence structure of the JPD. This entry deals with Markov networks. Bayesian networks are discussed in another entry. Markov networks are defined and the questions about how Markov networks can be constructed, how Markov networks can be learnt from data, and how uncertainty can be propagated when new evidence becomes available are also discussed.
Functional Networks
Authors: Castillo Enrique , Hadi Ali S.
Published: October 2006

Functional networks (FNs) are a general framework useful for solving a wide range of problems in various fields. In FNs, the network structure is not necessarily a black box; it is derived from the reality being modeled, that is, it is design‐driven. Unlike in neural networks (NNs), the neural functions in FNs are true multiargument, and different for all neurons. In FNs, neural functions are learned instead of weights as in NNs. In addition, neural functions can be forced to output the same values, thus leading to a system of functional equations that impose strong conditions on the neuron functions and allow simplification of the topology. FNs are illustrated by an example of application.
DNA Microarray Data, Statistical Analysis of
Authors: Datta Susmita
Published: October 2006

Modern microarray technology has revolutionized the state of biomedical research. With the advent of this technology, biologists can now observe the simultaneous expression profiles of thousands of genes in a single experiment. The large volume of data generated from these experiments has created a need for the development of appropriate statistical tools. Typically, such data sets contain high dimensional multivariate observations with few independent replications. We attempt to give a brief account of the developments of statistical methods in this fast growing area.
Missing Data: Sensitivity Analysis
Authors: Molenberghs Geert
Published: October 2006

With the growing amount of methodology to analyze incomplete data, the awareness has grown that the results of such an analysis may be very sensitive to the modeling assumptions made, many of which are not, strictly speaking, verifiable from the data. Therefore, a lot of the later work is devoted to the exploration of such sensitivities. For both categorical as well as continuous outcomes, we provide a broad definition for such sensitivity analyses, give an overview of methods, and provide some detail about a number of strategies that have become available.
Graph‐Theoretical Methods
Authors: Quiroz Adolfo J.
Published: October 2006

The use of graph‐theoretical structures, principally the Minimal Spanning Tree and thekNearest Neighbors Graph, allows the multivariate generalization of certain nonparametric statistical procedures and suggests the consideration of new ones. The areas of statistical application of graph theoretic procedures include the two‐sample problem, clustering, outlier identification, hypothesis testing, and dimension identification.
B
asu,
D
ebabrata
Authors: Ghosh Jayanta
Published: October 2006

This entry provides a short biography of Debabrata Basu who made pioneering contributions to mathematical statistics, sample surveys, foundations, and Bayesian analysis.
Flexible Designs
Authors: Posch Martin , Bauer Peter , Brannath Werner
Published: October 2006

Flexible designs allow for midtrial design adaptations in an adaptive interim analysis based on all information collected while controlling the type I error rate. Examples of such adaptations are, for example, sample‐size reassessment, addition or dropping of interim analyses, or dropping of treatment arms. The crucial feature of the adaptive procedure is that the adaptation rules need not be specified in advance.
Stability Study Designs
Authors: Daphne Lin Tsae‐Yun , Chen Chi Wan
Published: October 2006

A good stability study design is the key to a successful stability program. In this article, stability designs including full, bracketing, and matrixing designs will be exemplified. A full design involves complete testing of all factor combinations at all time points, which can be costly. The pharmaceutical industry would like to apply bracketing or matrixing design so that not every factor combination will be tested at every time point. The statistical aspects of these stability designs will be discussed in relation to the present ICH guidelines. Several commonly used criteria for design comparison will be presented. The statistical and regulatory considerations on the selection of stability design will also be discussed. The stability study should be well designed so the shelf life of the drug product can be estimated with a high degree of accuracy and precision.
Occupancy Distributions
Authors: Charalambides Ch. A.
Published: October 2006

Occupancy distributions are defined on the stochastic model of random allocation of balls of different kinds intondistinguishable urns. The reduction of the joint distribution of the occupancy numbers, when a specific number ofmballs are allocated, to the joint conditional distribution of independent random variables given their sum, when the number of balls allocated is unspecified, is a powerful technique in the study of occupancy distributions. Using this technique, the distribution of the numberKiof urns occupied byiballs each is derived in terms of the distribution of the independent random variables. In particular, the distribution of the numberK = n − K0of occupied urns is deduced and the distribution of the numberWkof balls required until the occupancy of a predetermined numberkof urns is obtained. Several applications and a generalization of the occupancy model are presented.
Stirling Numbers and Generalizations
Authors: Charalambides Ch. A.
Published: October 2006

The Stirling numbers of the first and second kind enumerate the permutations of a finite set that are decomposed into a given number of cycles and the partitions of a finite set into a given number of subsets, respectively. Basic properties of these numbers and their generalizations of probabilistic and statistical interest are reviewed. Specifically, explicit expressions, generating functions, recurrence relations, and other useful properties of these numbers are presented. Further, the Lah numbers and the generalized factorial coefficients, closely related to the Stirling numbers, are discussed. The noncentral and the associated Stirling and related numbers are briefly presented. The generalized Stirling and Lah numbers and, in particular, the
q
‐Stirling and
q
‐Lah numbers are only quoted. Probabilistic and statistical applications of the Stirling and related numbers in expressing the probability mass function of certain (a) urn‐model distributions, (b) occupancy distributions, (c) convolutions of truncated discrete distributions and (d) compound discrete distributions are exemplified.
Journal De La Société Française De Statistique
Authors: Caussinus Henri , de Falguerolles Antoine
Published: October 2006

This article outlines the history of the
Journal of the Statistical Society of Paris
(1860–1998), continuing as the
Journal of the French Statistical Society
. Editorial policies and representative articles are presented.
Chernoff‐Savage Theorem
Authors: Sen Pranab K.
Published: October 2006

The Chernoff‐Savage Theorem, in the setting of two independent samples, exploits the basic asymptotic properties of the two sample (empirical) distributions in a novel approach to the study of asymptotic normality of a general class of two‐sample linear rank statistics. Prior to the evolution of weak convergence of probability measures and contiguity of probability measures, both taking place in the 1960’s, this Theorem provided a completely new avenue of research in asymptotics in rank tests in a far more general set‐up comprising general linear models, time‐series, and multivariate as well as sequential models
Digamma and Trigamma Distributions
Authors: Sibuya Masaaki
Published: October 2006

Digamma distributions are mixture distributions* of logarithmic series distributions*, and hence heavy‐tailed distributions*, which have two parameters. The distributions vary widely with the parameter values; if one parameter is larger, the distribution is close to the logarithmic series distributions*. If this parameter is near zero, the distribution is reduced to trigamma distributions, which are close to zeta distributions* or Zipf's law*.
Coincidences and Patterns in Sequences
Authors: Dasgupta Anirban
Published: October 2006

This entry provides a contemporary exposition at a moderately quantitative level of the distribution theory associated with sequences and patterns in iid multinomial trials, the birthday problem, and the matching problem. The section on patterns includes the classic distribution theory for waiting time for runs and more general patterns, and their means and moments. It also includes the central limit theorem and a.s. properties of the longest run, and modern applications to DNA sequence alignment. The section on birthdays reviews the Poisson approximation in the classical birthday problem, with new bounds on the total variation distance. It also includes a number of variants of the classic birthday problem, including the case of unequal probabilities, similar triplets, and the Bayesian version with Dirichlet priors on birthday probabilities. A new problem called the strong birthday problem with application to criminology is introduced. The section on matching covers the Poisson asymptotics, errors of Poisson approximations, and some variants such as near matches. It also briefly reviews the recent extraordinary developments in the area of longest increasing subsequences in random permutations. The entry provides a large number of examples, many not well known, to help a reader have a feeling for these questions at an intuitive level
De novo CD5+ diffuse large B cell lymphoma with basophilia in the peripheral blood: Successful treatment with autologous peripheral blood stem cell transplantation
Authors: Tokuhira Michihide , Watanabe Reiko , Iizuka Atsushi , Sekiguchi Yasunobu , Nemoto Tomoe , Hanzawa Kyoko , Takamatsu Ichiro , Maruyama Taro , Tamaru Jun‐ichi , Itoyama Shinji , Suzuki Hiroshi , Takeuchi Tsutomu , Mori Shigehisa
Published: October 2006

Basophils play an important role in allergic inflammation and are pathologically related to hematological disturbances, such as iron deficiency anemia and myeloproliferative disorders; however, they are only rarely encountered in lymphoid malignancies. Here, we report the case of a 33‐year‐old man with a bulky mass of the small intestine, multiple paraaortic lymphoadenopathy, pleural effusion, and ascites, who was diagnosed as a case of de novo CD5+ diffuse large B cell lymphoma (DLBCL). This patient showed a marked elevation of the basophil count in the peripheral blood, which appeared to run in parallel with the tumor burden. High dose chemotherapy followed by autologous peripheral blood cell transplantation yielded complete remission, and the patient has remained disease free for 5 years. To the best of our knowledge, this is the first report of a case of de novo CD5+ DLBCL showing marked elevation of the PB basophil count. Am. J. Hematol. 2006. © 2006 Wiley‐Liss, Inc.
Polymer complexes: supramolecular modeling for determination and identification of the bond lengths in novel polymer complexes from their infrared spectra
Authors: Mubarak Ahmed T. , El‐Sonbati A. Z. , El‐Bindary A. A. , Issa R. M. , Kera H. M.
Published: October 2006

Synthesis and characterization of allyl propenyl‐2‐(4‐derivatives phenylazo)butan‐3‐one (HLn) are described. The monomers obtained contain NN and carbonyl functional groups in different positions with respect to the allyl group. This structural difference affects the stereochemical structure of the uranyl polymer complexes prepared by the direct reaction of uranyl acetate with the monomers. The polymer complexes are characterized by elemental analyses, 1H and 13C NMR, electronic and vibrational spectroscopy and other theoretical methods. The bonding sites of the hydrazone are deduced from IR and NMR spectra and each of the ligands were found to bond to the UO22+ ion in a bidentate fashion. The monomers obtained contain NN and carbonyl functional groups in different positions with respect to the allyl group. IR spectra show that the allyl azo homopolymer (HLn) acts as a neutral bidentate ligand by coordinating via the two oxygen atom of the carbonyl group, thereby forming a six‐membered chelating ring. The υ3 frequency of UO22+ has been shown to be a good molecular probe for studying the coordinating power of the ligands. The υ3‐values of UO22+ from IR spectra have been used to calculate the force constant, FUO (in 10−8 N/Å) and the bond length RUO (in Å) of the UO bond. We adopted a strategy based upon both theoretical and experimental investigations. The theoretical aspects are described in terms of the well‐known theory of 5d–4f transitions. The necessary structural data (coordination geometries and electronic structures) are determined from a framework for the modeling of novel polymer complexes. The Wilson, G. F. matrix method, Badger's formula and the Jones and El‐Sonbati equations were used to determine the stretching and interaction force constants from which the UO bond distances were calculated. The bond distances of these complexes were also investigated. The effect of Hamett's constant is also discussed. Copyright © 2006 John Wiley & Sons, Ltd.
EGF receptor clustering is induced by a 0.4 mT power frequency magnetic field and blocked by the EGF receptor tyrosine kinase inhibitor PD153035
Authors: Jia Caili , Zhou Zhenjie , Liu Renchen , Chen Shude , Xia Ruohong
Published: October 2006

Atomic force microscopy (AFM), transmission electron microscopy (TEM), and confocal laser scanning microscopy were used to investigate the effects of a 50 Hz 0.4 mT magnetic field (MF) on the clustering of purified epidermal growth factor receptors (EGFRs) and EGFRs in Chinese hamster lung (CHL) cell membrane. The results demonstrate that exposing purified EGFRs to the MF for 30 min induces receptor clustering. The peak height of apparent clusters increased from 1.42 ± 0.18 (sham‐exposed) to 3.08 ± 0.38 nm (exposed) while the mean half‐width increased from 21.7 ± 2.2 to 33.0 ± 4.0 nm. A similar effect was also observed by TEM. Treatment of purified EGFR with PD153035 (PD), an EGFR‐specific tyrosine kinase (TK) inhibitor, inhibited the MF‐induced EGFR clustering of the purified proteins, an effect also observed for the receptors in cell membrane in the absence of EGF. These results strongly suggest that the 50 Hz 0.4 mT MF interferes with the EGFR signaling pathway, most likely by interacting with the cytoplasmic TK domain. Bioelectromagnetics 28:197–207, 2007. © 2006 Wiley‐Liss, Inc.
Cleavage and survival of Xenopus embryos exposed to 8‐T static magnetic
Authors: Eguchi Yawara , Ueno Shoogo , Kaito Chikara , Sekimizu Kazuhisa , Shiokawa Koichiro
Published: October 2006

The original article to which this Erratum refers was published in Bioelectromagnetics 27:307–313.
A comparison of self‐reported cellular telephone use with subscriber data: Agreement between the two methods and implications for risk estimation
Authors: Schüz Joachim , Johansen Christoffer
Published: October 2006

Epidemiologic studies on adverse health effects of cellular telephone use have assessed exposure either by self‐reported use based on questionnaire data or by using data on subscriptions for a cellular telephone provided by network operators. With the latter approach, subjects are misclassified when they regularly use a cellular telephone subscribed in someone else's or in a company name or when they subscribe for a cellular telephone which they use only occasionally. Self‐reported use is hampered by recall difficulties and possible differential participation by exposure. In Denmark, we conducted a retrospective cohort study of cellular telephone subscribers (including the entire Danish population) and a case‐control study on brain tumors and cellular telephone use (with 1355 participants) and, thus, had the opportunity to compare the two exposure measures with two large‐scale data sets, using self‐reported use as a “gold standard.” Overall, there was a fair agreement (kappa value of 0.30, 95% confidence interval 0.23–0.36), with a low sensitivity (30%) and a high specificity (94%). Agreement was slightly better for controls, and low‐grade glioma cases compared to high‐grade glioma cases and meningioma cases. A comparison of odds ratios (OR) of the case‐control data set based on either self‐reported use or on subscriber data shows no major differences, giving OR of 0.7 and 0.6 for acoustic neuroma, 0.9 and 1.1 for glioma and 0.9 and 0.7 for meningioma. A discussion of the two exposure measures reveals that they both have limitations with regard to a potential underestimation of an association and there is some concern whether they are good enough to allow a detection of possibly only subtle changes in risk. These limitations can be minimized in prospective follow‐up studies. Bioelectromagnetics. © 2006 Wiley‐Liss, Inc.
Primary malignant hepatic epithelioid hemangioendothelioma
Authors: Mehrabi Arianeb , Kashfi Arash , Fonouni Hamidreza , Schemmer Peter , Schmied Bruno M. , Hallscheidt Peter , Schirmacher Peter , Weitz Jurgen , Friess Helmut , Buchler Markus W. , Schmidt Jan
Published: October 2006

Malignant hepatic epithelioid hemangioendothelioma (HEH) is a rare malignant tumor of vascular origin with unknown etiology and a variable natural course. The authors present a comprehensive review of the literature on HEH with a focus on clinical outcome after different therapeutic strategies. All published series on patients with HEH (n = 434 patients) were analyzed from the first description in 1984 to the current literature. The reviewed parameters included demographic data, clinical manifestations, therapeutic modalities, and clinical outcome. The mean age of patients with HEH was 41.7 years, and the male‐to‐female ratio was 2:3. The most common clinical manifestations were right upper quadrant pain, hepatomegaly, and weight loss. Most patients presented with multifocal tumor that involved both lobes of the liver. Lung, peritoneum, lymph nodes, and bone were the most common sites of extrahepatic involvement at the time of diagnosis. The most common management has been liver transplantation (LTx) (44.8% of patients), followed by no treatment (24.8% of patients), chemotherapy or radiotherapy (21% of patients), and liver resection (LRx) (9.4% of patients). The 1‐year and 5‐year patient survival rates were 96% and 54.5%, respectively, after LTx; 39.3% and 4.5%, respectively, after no treatment, 73.3% and 30%, respectively, after chemotherapy or radiotherapy; and 100% and 75%, respectively, after LRx. LRx has been the treatment of choice in patients with resectable HEH. However, LTx has been proposed as the treatment of choice because of the hepatic multicentricity of HEH. In addition, LTx is an acceptable option for patients who have HEH with extrahepatic manifestation. Highly selected patients may be able to undergo living‐donor LTx, preserving the donor pool. The role of different adjuvant therapies for patients with HEH remains to be determined. Cancer 2006. © 2006 American Cancer Society
Acute myeloid leukemia: Epidemiology and etiology
Authors: Deschler Barbara , Lübbert Michael
Published: October 2006

Acute myeloid leukemias (AMLs) are infrequent, yet highly malignant neoplasms responsible for a large number of cancer‐related deaths. The incidence has been near stable over the last years. It continuously shows 2 peaks in occurrence in early childhood and later adulthood. With an incidence of 3.7 per 100,000 persons and an age‐dependent mortality of 2.7 to nearly 18 per 100,000 persons, there is a rising awareness in the Western world of AML's special attributes resulting from an ever‐aging population. To objectively describe epidemiologic data on this patient population, recent publications were evaluated to make transparent the current trends and facts. A review of the literature is presented, reflecting highlights of current research with respect to AML etiology. To estimate outcome and discuss informed treatment decisions with AML patients of different age groups and different biologic risk categories, it is mandatory to consider that the outcome results reported in clinical trials were until now heavily biased toward younger patients, whereas the overall dismal prognosis documented in population‐based studies most likely reflects the exclusion of older patients from aggressive treatment. The etiology for most cases of AML is unclear, but a growing knowledge concerning leukemogenenic agents within chemotherapy regimens for other malignancies is already available. This includes specific associations of the most frequent balanced translocations in AML, including the “good‐risk” abnormalities comprised by the core binding factor leukemias (i.e., AML with the translocation (8;21) and inversion of chromosome 16, and acute promyelocytic leukemia with the translocation (15;17)). In contrast to these genetic alterations, epigenetic lesions, e.g., promoter silencing by hypermethylation of the p15/INK4b and other genes, are increasingly recognized as important in the pathogenesis of AML. Cancer 2006. © 2006 American Cancer Society.
Prognosis of medullary thyroid carcinoma
Authors: Roman Sanziana , Lin Rong , Sosa Julie Ann
Published: October 2006

BACKGROUND.

Medullary thyroid cancer (MTC) is a rare cancer. There is a relative paucity of data over the last decade with regard to the prognosis of these patients. Therefore, the authors used the population‐based Surveillance, Epidemiology, and End Results (SEER) registry to update what to their knowledge is one of the largest series of patients with MTC reported to date.

METHODS.

All patients with a diagnosis of MTC with active follow‐up in the SEER database from 1973 to 2002 were included. Univariate and multivariate regression analyses were used to assess the associations between demographic, clinical, and pathologic characteristics of patients and survival.

RESULTS.

A total of 1252 patients with MTC were identified over 29 years of follow‐up. In all, 87% of patients were white and 60% were female, with a mean age of 50 years. Although many variables were significant on univariate analysis, SEER stage and age at diagnosis were found to be the strongest predictors of survival in the multivariate analysis. Prognosis was poor in patients with advanced disease (hazards ratio [HR], 4.47), or those age >65 years (HR, 6.55). Patients who underwent surgery fared better than those who did not. Overall, 51% of patients had less than the currently recommended treatment guidelines for MTC. Adjuvant radiation therapy was found to be independently associated with a decreased survival (HR, 1.65).

CONCLUSIONS.

Stage of disease and age at diagnosis were found to be the strongest predictors of survival for patients with MTC. To the authors' knowledge there has been no change in stage at diagnosis or asignificant improvement in survival noted over the last 30 years. Many patients underwent surgery that was deemed less than optimal for stage of disease. Cancer 2006. © 2006 American Cancer Society.
GSNO attenuates EAE disease byS‐nitrosylation‐mediated modulation of endothelial‐monocyte interactions
Authors: Prasad Ratna , Giri Shailendra , Nath Narender , Singh Inderjit , Singh Avtar K.
Published: October 2006

S‐Nitrosoglutathione (GSNO) is an endogenous nitric oxide carrier and recently, has been documented for its anti‐inflammatory effects in rat model of cerebral ischemia (Khan et al. (2005) J Cereb Blood Flow Metab 25:177–192). Here, we explored the neuroprotective effects mediated by GSNO in Lewis rat model of EAE and its mechanism of action usingin vitromodel of monocyte‐endothelial cell interaction. Oral administration of GSNO attenuated the clinical disease course in EAE animals by inhibiting the infiltration of vascular immune cells in the CNS that subsequently led to the reduction in the expression of proinflammatory cytokines and consequently limited demyelination. Based on the inhibition in infiltration of immune cells, we hypothesized that GSNO modulated endothelial cell activation that led to reduce cellular infiltration in the CNS. Using anin vitromodel, we established that GSNO inhibited monocyte adhesion to the activated endothelial cell, which was mediated by down regulation of endothelial cell adhesion molecules (CAMs). The mechanism by which GSNO modulated CAMs expression appeared to be viaS‐nitrosylation of p65, which consequently inhibited nuclear factor kappa B (NF‐κB) activation in endothelial cells. These observations suggest that GSNO exerts its protective effects in EAE by inhibition of cellular infiltration into the CNS byS‐nitrosylation of p65, thereby modulating NF‐κB‐CAMs pathway in endothelial cells. © 2006 Wiley‐Liss, Inc.
Medical history, cigarette smoking and risk of acoustic neuroma: An international case‐control study
Authors: Schoemaker M.J. , Swerdlow A.J. , Auvinen A. , Christensen H.C. , Feychting M. , Johansen C. , Klæboe L. , Lönn S. , Salminen T. , Tynes T.
Published: October 2006

Acoustic neuroma (vestibular schwannoma) is a benign tumor of the vestibulocochlear nerve. Its recorded incidence is increasing but risk factors for this tumor have scarcely been investigated. We conducted a population‐based case‐control study of risk factors for acoustic neuroma in the UK and Nordic countries, including 563 cases and 2,703 controls. Tumor risk was analyzed in relation to medical history and cigarette smoking. Risk of acoustic neuroma was significantly raised in parous compared with nulliparous women (OR = 1.7, 95% CI: 1.1–2.6), but was not related to age at first birth or number of children. Risk was not associated with a history of allergic disease, past head injury, past diagnosis of a neoplasm or birth characteristics, but was significantly raised for past diagnosis of epilepsy (OR = 2.5, 95% CI: 1.3–4.9). Tumor risk was significantly reduced in subjects who had ever regularly smoked cigarettes (OR = 0.7, 95% CI: 0.6–0.9), but the reduction applied only to current smokers (OR = 0.5, 95% CI: 0.4–0.6), not ex‐smokers (OR = 1.0, 95% CI: 0.8–1.3). The reduced risk of acoustic neuroma in smokers and raised risk in parous women might relate to sex hormone levels, or smoking might suppress tumor growth, but effects of parity and smoking on timing of diagnosis of the tumor are also a potential explanation. The raised risk in relation to past diagnosis of epilepsy might be a surveillance artefact or imply that epilepsy and/or antiepileptic medication use predispose to acoustic neuroma. These findings need replication by other studies and possible mechanisms need to be clarified. © 2006 Wiley‐Liss, Inc.
In vitro biocompatibility of fluorcanasite glass‐ceramics for bone tissue repair
Authors: Bandyopadhyay‐Ghosh S. , Reaney I.M. , Brook I.M. , Hurrell‐Gillingham K. , Johnson A. , Hatton P.V.
Published: October 2006

Fluorcanasite glass‐ceramics were produced by controlled two stage heat‐treatment of as‐cast glasses. These glasses were modified from stoichiometric fluorcanasite composition by either adding P2O5 or altering the molar ratios of Na2O and CaO. Commercial bioactive 45S5 Bioglass® was also prepared in‐house to evaluate the relative in vitro biocompatibility of fluorcanasite glass‐ceramics. The scanning electron microscopy (SEM) images showed that cells had colonized the surfaces of fluorcanasite glass‐ceramics to form a confluent sheet. Quantitative MTT assay results were in good agreement with the qualitative SEM observations. It was concluded that incorporation of excess calcium oxide or P2O5 in stoichiometric glass composition improved in vitro biocompatibility. Controlled heat‐treatment further improved the biological response of cultured bone cells to modified fluorcanasite glass‐ceramics when compared with their parent glasses. Ion release and pH data suggested a strong correlation between solubility (in particular, Na ion release) and biocompatibility. Reduced solubility, Na ion release, and related pH effects appeared to be the principal mechanisms responsible for improvement in in vitro biocompatibility. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Characterization of the structure and reactivity of monocopper–oxygen complexes supported by β‐diketiminate and anilido‐imine ligands
Authors: Gherman Benjamin F. , Tolman William B. , Cramer Christopher J.
Published: October 2006

Copper–oxygen complexes supported by β‐diketiminate and anilido‐imine ligands have recently been reported (Aboelella et al., J Am Chem Soc 2004, 126, 16896; Reynolds et al., Inorg Chem 2005, 44, 6989) as potential biomimetic models for dopamine β‐monooxygenase (DβM) and peptidylglycine α‐hydroxylating monooxygenase (PHM). However, in contrast to the enzymatic systems, these complexes fail to exhibit CH hydroxylation activity (Reynolds et al., Chem Commun 2005, 2014). Quantum chemical characterization of the 1:1 Cu‐O2 model adducts and related species (Cu(III)‐hydroperoxide, Cu(III)‐oxo, and Cu(III)‐hydroxide) indicates that the 1:1 Cu‐O2 adducts are unreactive toward substrates because of the weakness of the OH bond that would be formed upon hydrogen‐atom abstraction. This in turn is ascribed to the 1:1 adducts having both low reduction potentials and basicities. Cu(III)‐oxo species on the other hand, determined to be intermediate between Cu(III)‐oxo and Cu(II)‐oxyl in character, are shown to be far more reactive toward substrates. Based on these results, design strategies for new DβM and PHM biomimetic ligands are proposed: new ligands should be made less electron rich so as to favor end‐on dioxygen coordination in the 1:1 Cu‐O2 adducts. Comparison of the relative reactivities of the various copper–oxygen complexes as hydroxylating agents provides support for a Cu(II)‐superoxide species as the intermediate responsible for substrate hydroxylation in DβM and PHM, and suggests that a Cu(III)‐oxo intermediate would be competent in this process as well. © 2006 Wiley Periodicals, Inc. J Comput Chem, 2006
Flagellar apparatus of south‐seeking many‐celled magnetotactic prokaryotes
Authors: Silva Karen Tavares , Abreu Fernanda , Almeida Fernando P. , Keim Carolina Neumann , Farina Marcos , Lins Ulysses
Published: October 2006

Magnetotactic bacteria orient and migrate along geomagnetic field lines. Each cell contains membrane‐enclosed, nano‐scale, iron‐mineral particles called magnetosomes that cause alignment of the cell in the geomagnetic field as the bacteria swim propelled by flagella. In this work we studied the ultrastructure of the flagellar apparatus in many‐celled magnetotactic prokaryotes (MMP) that consist of several Gram‐negative cells arranged radially around an acellular compartment. Flagella covered the organism surface, and were observed exclusively at the portion of each cell that faced the environment. The flagella were helical tubes never as long as a complete turn of the helix. Flagellar filaments varied in length from 0.9 to 3.8 μm (average 2.4 ± 0.5 μm, n = 150) and in width from 12.0 to 19.5 nm (average 15.9 ± 1.4 nm, n = 52), which is different from previous reports for similar microorganisms. At the base of the flagella, a curved hook structure slightly thicker than the flagellar filaments was observed. In freeze‐fractured samples, macromolecular complexes about 50 nm in diameter, which possibly corresponded to part of the flagella basal body, were observed in both the P‐face of the cytoplasmic membrane and the E‐face of the outer membrane. Transmission electron microscopy showed that magnetosomes occurred in planar groups in the cytoplasm close and parallel to the organism surface. A striated structure, which could be involved in maintaining magnetosomes fixed in the cell, was usually observed running along magnetosome chains. The coordinated movement of the MMP depends on the interaction between the flagella of each cell with the flagella of adjacent cells of the microorganism. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Collagen types I, III, and V constitute the thick collagen fibrils of the mouse decidua
Authors: Spiess Karin , Zorn Telma Maria Tenório
Published: October 2006

A mammal's endometrium is deeply remodeled while receiving and implanting an embryo. In addition to cell proliferation and growth, endometrial remodeling also comprises synthesis and degradation of several molecular components of the extracellular matrix. All of these events are orchestrated by a precise sequence of ovarian hormones and influenced by several types of cytokines. As we have previously reported, an intriguing and rapid increase in collagen fibril diameter occurs in the decidualized areas of the endometrium, surrounding the implantation crypt, whereas collagen fibrils situated far from the embryo remain unchanged. Collagen fibrilogenesis is a complex molecular process coordinated by a number of factors, such as the types and amounts of glycosaminoglycans and proteoglycans associated with collagen molecules. Collagen genetic type, mechanical stress, aging, and other factors not yet identified also contribute to this development. A recent study suggests that thick fibrils from mouse decidua are formed, at least in part, by aggregation of thin fibrils existing in the stroma before the onset of decidualization. In the present ultrastructural study using single and double immunogold localization, we showed that both thin and thick collagen fibrils present in the mouse pregnant endometrium endometrium are heterotypic structures formed at least by type I, type III, and type V collagens. However, type V collagen predominates in the thick collagen fibrils, whereas it is almost absent of the thin collagen fibrils. The putative role of type V homotrimer in the rapid increase of the diameter of collagen fibrils of the mouse decidua is discussed. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Ischemia leads to delayed union during fracture healing: A mouse model
Authors: Lu Chuanyong , Miclau Theodore , Hu Diane , Marcucio Ralph S.
Published: October 2006

Vascular damage accompanying skeletal injury leads to an ischemic environment, and in clinical settings the extent of vascular damage is directly correlated with failure of skeletal repair. However, the exact mechanism(s) underlying ischemia‐related defects in bone healing are not well understood. To better understand the mechanism and to facilitate development of novel interventions to treat ischemic fractures, a mouse model of long bone fracture healing in an ischemic environment was created. Ischemia was induced by femoral artery resection prior to tibia fracture. Fractures were left unstabilized or were stabilized with custom‐designed external fixators. Animals with intact femoral vessels served as controls. Tissues from non‐stabilized fractures were analyzed at various times from 3 to 28 days after injury (n = 5/time point). Femoral artery resection severely impaired blood supply to the fractured limbs, and perfusion to the fracture sites did not recover until 14 days post‐injury. Ischemia significantly decreased the callus size (p < 0.05), and decreased bone (p < 0.05) and cartilage (p < 0.05) matrix production during healing of non‐stabilized fracture. The decreased formation of skeletal tissues in ischemic limbs was accompanied by decreased cell proliferation and increased apoptosis at early time points, and increased fibrous and fatty tissues adjacent to the fracture site during the third and fourth week after injury. These alterations led to a delayed‐union. Complete fracture healing was not achieved in the majority (day 21 = 4/5; day 28 = 5/5) of ischemic animals, while all control mice (n = 5/5) had evidence of bony bridging by day 21. The ratio of cartilage to bone was similar in ischemic and control limbs at days 7 and 10 in non‐stabilized fractures. In stabilized fractures, which healed through direct bone formation in the nonischemic controls, ischemia decreased the amount of bone formation at days 10 and 14 (n = 5/time point) but did not induce cartilage formation. These data reveal that an ischemic insult in the hind limb prior to fracture leads to a delayed union or a nonunion, but does not favor formation of cartilage over bone. This model will be useful for testing novel therapeutic regimens to stimulate fracture healing. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:51–61, 2007
Nonidentical and outlier duty cycles as factors accelerating UHMWPE wear in THA: A finite element exploration
Authors: Lundberg Hannah J. , Stewart Kristofer J. , Pedersen Douglas R. , Callaghan John J. , Brown Thomas D.
Published: October 2006

Wear rate and wear direction vary considerably within total hip arthroplasty (THA) patient cohorts. Third body effects and wide‐ranging differences in patient activity levels are two factors suspected of contributing to wear variability. A sliding‐distance‐coupled contact finite element formulation was used to test the hypothesis that nonidentical duty cycles (differing activities, or change of third body challenge) produce accelerations in polyethylene wear. Effects of nonidentical duty cycles, time‐variant femoral head roughening, and outlier gait inputs were investigated. Without femoral head roughening, combination walk/stair‐climb wear simulations did not result in appreciably higher volumetric wear than a walk‐only simulation, but when a roughened zone was included, walk/stair‐climb volumetric wear increased by approximately 57% above that of a similarly roughened walk‐only simulation. To investigate time‐variant femoral head roughening, wear simulations were begun with femoral head roughening at one location on the femoral head, switching to another location halfway through the simulation. Results varied depending on roughening sites, but cases of substantial increase in wear involved a transient jump in wear rate shortly after the change of head roughening location. Outlier duty cycles were simulated by increasing or decreasing the joint contact force and range of motion inputs, to levels at the 97.5th and 2.5th percentiles of a population of normal subjects. The resulting wear showed an increase or decrease closely proportional to the percentage by which each input (force or range of motion) was changed. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:30–43, 2007
Quantitative and topographical evaluation of ankle articular cartilage using high resolution MRI
Authors: Millington Steven A. , Li Bing , Tang Jinshan , Trattnig Siegfried , Crandall Jeff R. , Hurwitz Shepard R. , Acton Scott T.
Published: October 2006

The objectives of this study were to quantitatively evaluate the articular cartilage layers of the ankle and describe the cartilage topographical distribution across the joint surfaces using high resolution MRI and image segmentation. An anisotropic diffusion noise reduction algorithm and a directional gradient vector flow (dGVF) snake segmentation algorithm were applied to cartilage sensitive MR images. Eight cadaveric ankles were studied. Six repeated data sets were acquired in five of the ankles. Quantitative parameters were calculated for each cartilage layer; coefficients of variation (CV) were calculated from the six repeated data sets; and 3D thickness distribution maps were generated. The noise reduction algorithm produced marked image enhancement. Mean cartilage thickness ranged from 0.91 ± 0.08 mm in the fibula to 1.34 ± 0.14 mm in the talus. Mean cartilage volume was 3.32 ± 0.55 ml, 1.72 ± 0.25 ml, and 0.35 ± 0.06 ml for the talus, tibia, and fibula, respectively. Mean CV ranged 2.82%–5.04% for quantitative parameters in the talus and tibia. The reported noise reduction and segmentation technique allow precise extraction of ankle cartilage and 3D reconstructions show that the thickest cartilage occurs over the talar shoulders, where osteochondritits dissecans (OCD) lesions commonly occur. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:143–151, 2007