bluuebunny/crossref_metadata_2025 huggingface dataset:
Middle- and late-Holocene dune reactivation in the Nebraska Sand Hills, USA
Authors: Stokes Stephen , Swinehart James B.
Published: November 2007

A combination of optical dating of aeolian sand, and radiocarbon dating of palaeosols and interdune sediments, has allowed some refinements to the chronostratigraphy of the Nebraska Sand Hills. Our results directly confirm previous inferences that multiple phases of aeolian deposition, including megabarchan dune reactivation, occurred within the Sand Hills during the middle and late Holocene. Optical dates on stratified aeolian (barchan dune) sediments from two localities provide ages ranging from c. 6 ka to <300 years ago. Weakly developed palaeosols intercalated within the dune sediments and other forms of post-depositional modification indicate periods of relative stability and reduced dune mobilization. Optical dates on the upper 12-15 m of two dune exposures indicate repeated, possibly regionally correlative, reactivations which occurred between c. 400-500 and 200-300 years ago. Comparison of late-Holocene aeolian activity with local and regional palaeoclimatic proxy records suggests that dune reactivation may have occurred frequently, possibly in response to periods of extended (> 20 yr) drought.
Radiocarbon dating of a recent high latitude peat profile: Stor Åmyrân, northern Sweden
Authors: Oldfield F. , Thompson R. , Crooks P.R.J. , Gedye S.J. , Hall V.A. , Harkness D.D. , Housley R.A. , McCormac F.G. , Newton A.J. , Pilcher J.R. , Renberg I. , Richardson N.
Published: November 2007

The value of both high-precision (HP) and AMS 14C determinations in the fine-resolution dating of recent peat at Stor Åmyrân, near Umeå, northern Sweden has been explored. A detailed chronology of accumu lation, based on 14C, an occurrence of the Askja AD 1875 tephra and 241Am measurements has been derived for the last 700 years. This shows significant changes in the mass balance of the peat profile, with minimum rates of net carbon sequestration overlapping with the period of minimum spring and summer temperature documented by published tree-ring evidence. The paper presents a methodology for calculating empirically past changes in the rate of net carbon sequestration in boreal peatlands and for exploring the effects of climatic variations (and possible future global warming) on these rates.
A palaeoclimatic and palaeoceanographic record of the last 11 000 14C years from the Skagerrak-Kattegat, northeastern Atlantic margin
Authors: Hui Jiang  , Björck Svante , Knudsen Karen Luise
Published: November 2007

Marine sediments of about 116 m drilled onshore at Skagen near the northernmost tip of Jutland, Denmark, provides a continuous and detailed palaeoceanographic and palaeoenvironmental record of the last 11 000 14C years in the Skagerrak-Kattegat. The whole Younger Dryas was characterized by an arctic-subarctic environment where the North Jutland Current flows today, instead of being succeeded by a minor climate warming at about 10 600 BP as recorded in the southern Kattegat and in the areas strongly influenced by the Baltic Current and currents along the Swedish west coast. The changes in components of diatom assemblages, combined with previously published benthic foraminiferal data from the present core, reflect a two-step climatic warming and consequently environmental change during the transition from the Younger Dryas to the Preboreal. An abrupt warming of the sea surface waters took place at about 10 100 BP, which resulted from the inflow of warm Atlantic surface water. Summer sea-surface temperature rose about 8°C. It had a great influence on the surface water of the Skagerrak-Kattegat and shallow areas, but had only little effect on the bottom water in the deep parts of the region. Warming of bottom water occurred a few hundred years after the first warming, and is most likely simultaneous with the end of the Preboreal oscillation. A warm period at 7700-5100 BP is registered by diatom assemblages that resulted from the opening of the English Channel because of eustatic sea-level rise, and by larger influence of the Norwegian Coastal Current and currents along the Swedish west coast. A climate cooling was documented at about 5100 BP by acceleration of the South Jutland Current.
The history of Fagus forest in southwestern Sweden during the last 1500 years
Authors: Björkman Leif
Published: November 2007

In the recent past, Fagus forests in southwestern Sweden were more common and widespread than today. The Fagus forest area has decreased considerably due to cultural activities, mainly during the eighteenth and nineteenth centuries. The pollen records of two small adjacent forest hollows (lying c. 50 m apart) in the Bocksten area in central Halland indicate that the pre- Fagus forest was of a rich memoral type with many woody taxa present. Quercus, Tilia, Alnus, and Corylus were important components of this forest type. Fagus became established in the area around 1450 14C years BP, and rapidly became dominant in the forest. The expansion of Fagus was remarkably rapid, and probably facilitated by slight human disturbance. The rather pure Fagus stands found today in the area are a product of recent human activities. The high pollen percentages of Tilia at one of the sites (site A) until 200 BP is remarkable, and stands in contrast to the picture seen in regional-scale pollen diagrams from Sweden. At this site, Tilia grew in a mixture with Fagus, Quercus and Corylus for almost 1200 years until the stand was suddenly cleared c. 200 BP. At the other site (B), Tilia shows a gradual decrease beginning before the establishment of Fagus, which is in agreement with the regional picture. It is evident that stand-level differences in vegetation is not possible to detect with conventional pollen diagrams based on regional-scale sites. Different grazing regimes, or human influence, may have caused these stand-scale differences in vegetation. The boreo-nemoral forest type found today in the studied area is domi nated by intensively managed Picea plantations and Fagus stands. This forest type has little resemblance to the vegetation that existed during earlier periods.
Dinoflagellate cysts as indicators of pollution and past climate in a Norwegian fjord
Authors: Thorsen Thor A. , Dale Barrie
Published: November 2007

Two sediment cores from a semi enclosed eutrophic fjord and one from the open adjoining fjord revealed a sequence of dinoflagellate cyst assemblage changes during the past 1000 years. Higher percentages of the warmer water cyst Lingulodinium machaerophorum (Deflandre and Cookson) Wall 1967 (10-41%) within the restricted fjord correspond with the Medieval Warm Period, and is succeeded by decreased percent ages (5%) from about AD 1380 corresponding with the onset of the more adverse climate of the 'Little Ice Age'. Two peaks of Operculodinium centrocarpum (Deflandre and Cookson) Wall 1967, at about AD 1700 followed by decreased total cyst concentrations in the enclosed fjord and increased total cyst concentrations in the open fjord, is used to correlate cores from the two fjords, and suggests climatic change. Increased pollution from sewage discharge as the human population of the city of Bergen expanded is suggested by decreased total cyst concentrations (cyst/g dry sediment) accompanied by peak concentrations of O. centrocar pum at about 1850 and a peak concentration of cysts of the heterotrophic species Protoperidinium conicum (Gran) Balech 1974 at about 1930. A smaller peak of O. centrocarpum together with slightly increased total cyst concentrations towards the top of the cored sediments may indicate improved water conditions after sewage discharge into the inner fjord was reduced in the 1980s.
Mid- and late-Holocene vegetation, surface weathering and glaciation, Fjallsjökull, southeast Iceland
Authors: Rose J. , Whiteman C.A. , Lee J. , Branch N.P. , Harkness D.D. , Walden J.
Published: November 2007

A natural section at the southern margin of Fjallsjökull in southeastern Iceland provides evidence of a mid-Holocene land-surface that has been deformed by 'Little Ice Age' glaciation. Deformation is inter preted as compression around coarse gravel core and extension along deformable silts. Restoration of the original sedimentary units reveals a succession of lake sediments and fan gravels, with pollen and wood macro fossil remains preserved in the lake silts. Vegetational and palaeogeographical reconstruction indicates that small ponds existed at the site surrounded by a mosaic of birch woodland and grassland. Radiocarbon dates spanning a period from 4200 to 3750 BP indicate that the basins were infilled rapidly over a period of about 500 years by stream sedimentation. Colour changes in the upper part of the sediment sequence and relatively high frequency dependent magnetic susceptibility values on the clay fractions of the sediments indicate that iron minerals were mobilized and oxidized in response to the weathering processes that became established on the new land surface. The 'Little Ice Age' glaciation crossed the area at the end of the nineteenth century and the site was deglacierized in 1965. This is the first record of mid-Holocene vegetation from southeast Iceland and the identification of Plantago lanceolata type pollen from the organic silts is the first pre-Landnam record of this species. Formation of the basins in which the mid-Holocene lake sediments accumulated provides indirect evidence for mid-Holocene glaciation.
Interdisciplinary investigations of the end of the Norse Western Settlement in Greenland
Authors: Barlow L.K. , Sadler J.P. , Ogilvie A.E.J. , Buckland P.C. , Amorosi T. , Ingimundarson J.H. , Skidmore P. , Dugmore A.J. , McGovern T.H.
Published: November 2007

The loss of the Norse Western Settlement in Greenland around the mid-fourteenth century has long been taken as a prime example of the impact of changing climate on human populations. This study employs an interdisciplinary approach combining historical documents, detailed archaeological investigations, and a high-resolution proxy climate record from the Greenland Ice Sheet Project 2 (GISP2) to investigate possible causes for the end of this settlement. Historical climate records, mainly from Iceland, contain evidence for lowered temperatures and severe weather in the north Atlantic region around the mid-fourteenth century. Archaeological, palaeoecological and historical data specifically concerning the Western Settlement suggest that Norse living conditions left little buffer for unseasonable climate, and provide evidence for a sudden and catastrophic end around the mid-fourteenth century. Isotopic data from the GISP2 ice core provide annual- and seasonal-scale proxy-temperature signals which suggest multiyear intervals of lowered temperatures in the early and mid-fourteenth century. The research synthesized here suggests that, while periods of unfavourable climatic fluctuations are likely to have played a role in the end of the Western Settlement, it was their cultural vulnerabilities to environmental change that left the Norse far more subject to disaster than their Inuit neigh bours.
Cluster analysis and related techniques in medical research
Authors: McLachlan GJ
Published: November 2007

In this paper we review methods of cluster analysis in the context of classifying patients on the basis of clinical and/or laboratory type observations. Both hierarchical and non-hierarchical methods of clustering are considered, although the emphasis is on the latter type, with particular attention devoted to the mixture likelihood-based approach. For the purposes of dividing a given data set into g clusters, this approach fits a mixture model of g components, using the method of maximum likelihood. It thus provides a sound statistical basis for clustering. The important but difficult question of how many clusters are there in the data can be addressed within the framework of standard statistical theory, although theoretical and computational difficulties still remain. Two case studies, involving the cluster analysis of some haemophilia and diabetes data respectively, are reported to demonstrate the mixture likelihood-based approach to clustering.
Principal component analysis and exploratory factor analysis
Authors: Joliffe IT , Morgan Bjt
Published: November 2007

In this paper we compare and contrast the objectives of principal component analysis and exploratory factor analysis. This is done through consideration of nine examples. Basic theory is presented in appendices. As well as covering the standard material, we also describe a number of recent developments. As an alternative to factor analysis, it is pointed out that in some cases it may be useful to rotate certain principal components if and when that is appropriate.
Modelling patterns of agreement and disagreement
Authors: Agresti Alan
Published: November 2007

This article presents a survey of ways of statistically modelling patterns of observer agreement and disagreement. Main emphasis is placed on modelling inter-observer agreement for categorical responses, both for nominal and ordinal response scales. Models discussed include (1) simple cell-probability models based on Cohen's kappa that focus on beyond-chance agreement, (2) loglinear models for square tables, such as quasi-independence and quasi-symmetry models, (3) latent class models that express the joint distribution between ratings as a mixture of clusters for homogeneous subjects, each cluster having the same 'true' rating, and 4) Rasch models, which decompose subject-by-observer rating distributions using observer and subject main effects. Models can address two distinct components of agreement - strength of association between ratings, and similarity of marginal distributions of the ratings.
Incomplete data in repeated measures analysis
Authors: Gornbein Jeffrey A , Lazaro Carlos G , Little Roderick JA
Published: November 2007

Complete (or balanced) repeated measures data arise when all subjects in a study are measured at the same set of time points. Data are often incomplete, because measurements are missed, or the design of the study results in subjects being measured at different sets of time points. This article reviews methods of analysis for incomplete repeated-measures data of this form, from an applied statistician's perspective. Limitations of approaches that (a) ignore between-subject variation, or (b) impute for missing values are discussed. Two methods are advocated that are relatively easy to implement using existing software, namely between-subject analysis of within-subject summary measures, and maximum likelihood based on a model for the data. Methods are applied and compared on four real-data examples with varied analytical objectives.
Repeated assessment of risk factors in survival analysis
Authors: Andersen Per Kragh
Published: November 2007

Regression models for survival data with time-dependent covariates are considered. We review estimation in the Cox regression model and discuss problems in connection with data requirements for the analysis, with interpretation of results and with prediction based on such a model. In particular, we discuss how the latter problems may be approached within an extended (Markov process) model. A clinical trial in liver cirrhosis is used for illustration.
AIDS: the statistical basis for public health
Authors: De Angelis D. , Day NE , Gore SM , Gilks WR , McGee MA
Published: November 2007

The backcalculation method has been extensively used in AIDS modelling and forecasting. Knowledge of reported AIDS cases, information on the time between HIV infection and onset of AIDS, and assumptions on the rate at which infections occurs, can be used to reconstruct the past history of the HIV epidemic, as well as to provide short term predictions of AIDS incidence. Uncertainty in the three components of the backcalculation method and the increasingly available information on HIV prevalence must be taken into account in order to provide realistic projections. In this paper we discuss ways of acknowledging uncertainty and suggest a Bayesian formulation of the backcalculation idea as a means of combining into a single model both random and systematic variation as well as prior information.
Fisher's method of scoring in statistical image reconstruction: comparison of Jacobi and Gauss-Seidel iterative schemes
Authors: Hudson H Malcolm , Jun Ma
Published: November 2007

Many algorithms for medical image reconstruction adopt versions of the expectation-maximization (EM) algorithm. In this approach, parameter estimates are obtained which maximize a complete data likelihood or penalized likelihood, in each iteration. Implicitly (and sometimes explicitly) penalized algorithms require smoothing of the current reconstruction in the image domain as part of their iteration scheme.

In this paper, we discuss alternatives to EM which adapt Fisher's method of scoring (FS) and other methods for direct maximization of the incomplete data likelihood. Jacobi and Gauss-Seidel methods for non-linear optimization provide efficient algorithms applying FS in tomography. One approach uses smoothed projection data in its iterations.

We investigate the convergence of Jacobi and Gauss-Seidel algorithms with clinical tomographic projection data.
Combining estimates of the odds ratio: the state of the art
Authors: Emerson John D
Published: November 2007

Medical research commonly relies on the combination of 2 x 2 tables of counted data for making inferences about treatment effects or about the causes of disease. This article reviews point estimation and interval estimation for a common odds ratio. Traditional methods for providing these estimates face special challenges, and sometimes break down, when the data are sparse. Recent research provides practical alternatives to the traditional methods, and uses new computer algorithms to make them readily available in microcomputer software packages. This article illustrates and compares the various methods and offers recommendations for using the newer methods when analysing data sets of moderate size.
Statistical models for the analysis of ordered categorical data in public health and medical research
Authors: Etzioni Ruth D , Fienberg Stephen E , Gilula Zvi , Haberman Shelby J
Published: November 2007

In the late 1970s statisticians extended the methods for analysing loglinear and logit models for cross-classified categorical data to incorporate information about the ordinal structure of the categories corresponding to some of the classification variables. In this paper we review one class of such extensions known as association models. We consider association models with and without order restrictions on the parameters and we use these models to answer research questions about several medical examples involving ordered categorical data. We emphasize the interpretation of parameters in the association models and how this relates to the research questions of interest.
Econometric mixture models and more general models for unobservables in duration analysis
Authors: Heckman James J , Taber Christopher R
Published: November 2007

This paper considers models for unobservables in duration models. It demonstrates how cross-section and time-series variation in regressors facilitates identification of single-spell, competing risks and multiple spell duration models. We also demonstrate the limited value of traditional identification studies by considering a case in which a model is identified in the conventional sense but cannot be consistently estimated.
Bayesian analyses of two-treatment crossover studies
Authors: Grieve Andrew P
Published: November 2007

This review covers Bayesian analyses of two-treatment crossover studies. The main emphasis is placed on the analysis of continuous data although we also consider dichotomous responses. Studies discussed include (1) the simple two-period, two-treatment crossover, (2) the two-period crossover with one baseline measurement, (3) the two-period crossover with two baselines and (4) the extra-period design with two treatment sequences.
Statistical models for cancer screening
Authors: Stevenson CE
Published: November 2007

This paper reviews the application of statistical models to planning and evaluating cancer screening programmes. Models used to analyse screening strategies can be classified as either surface models, which consider only those events which can be directly observed such as disease incidence, prevalence or mortality, or deep models, which incorporate hypotheses about the disease process that generates the observed events. This paper focuses on the latter type. These can be further classified as analytic models, which use a model of the disease to derive direct estimates of characteristics of the screening procedure and its consequent benefits, and simulation models, which use the disease model to simulate the course of the disease in a hypothetical population with and without screening and derive measures of the benefit of screening from the simulation outcomes. The main approaches to each type of model are described and an overview given of their historical development and strengths and weaknesses. A brief review of fitting and validating such models is given and finally a discussion of the current state of, and likely future trends in, cancer screening models is presented.
Spatial statistical methods in environmental epidemiology: a critique
Authors: Elliott Paul , Martuzzi Marco , Shaddick Gavin
Published: November 2007

Despite recent advances in the available statistical methods for geographical analysis, there are many constraints to their application in environmental epidemiology. These include problems of data availability and quality, especially the lack in most situations of environmental exposure measurements. Methods for disease 'cluster' investigation, point source exposures, small-area disease mapping and ecological correlation studies are critically reviewed, with the emphasis on practical applications and epidemiological interpretation. It is shown that, unless dealing with rare diseases, high specificity exposures and high relative risks, cluster investigation is unlikely to be fruitful, and is often complicated by the post hoc nature of such studies. However, it is recognized that in these circumstances proper assessment of the available data is often required as part of the public health response. Newly availabe methods, particularly in Bayesian statistics, offer an appropriate framework for geographical analysis and disease mapping. Again, it is uncertain whether they will give important clues as to aetiology, although they do give valuable description. Perhaps the most satisfactory approach is to test a priori hypotheses using a geographical database, although problems of interpretation remain.
Generalized additive models for medical research
Authors: Hastie Trevor , Tibshirani Robert
Published: November 2007

This article reviews flexible statistical methods that are useful for characterizing the effect of potential prognostic factors on disease endpoints. Applications to survival models and binary outcome models are illustrated.
Extending the elements of tree-structured regression
Authors: Segal Mark R
Published: November 2007

The usage of tree-structured or recursive partitioning methods has grown steadily in the decade since the appearance of the definitive monograph 'Classification and Regression Trees'. 1 Accompanying this growth have been many methodologic and software extensions that have served to give the tree-structured approach even wider applicability. This overview highlights some of these developments, emphasizing the regression setting. An illustrative example describes how tree-structured regression, modified to handle right-censored, left-truncated survival data with time-dependent covariates, can be used to assess whether rates of progression from HIV to AIDS have changed over time.
The analysis of the EEG
Authors: Gasser Theo , Molinari Luciano
Published: November 2007

The quantitative analysis of the electroencephalogram (EEG) relies heavily on methods of time series analysis. A quantitative approach seems indispensable for research (be it clinical or basic neurophysical research), but it can also be a useful information for purely clinical purposes. Apart from the ongoing spontaneous EEG, evoked potentials (EPs) also play an important role. They can be elicited by simple sensory stimuli or more complex stimuli. Their analysis requires methods which are different from those for the spontaneous EEG. Those methods operate usually in the time domain and offer many challenging problems to statisticians. Methods for analysing the spontaneous EEG usually work in the frequency domain in terms of spectra and coherences. Biomedical engineers who take care of the equipment are usually also trained in time series analysis. Thus, they have contributed much more to methodological progress for analysing EEGs and EPs, compared with statisticians. However, the availability of a sample of subjects, and the associated problems in modelling followed by an inferential analysis could make a larger influence from the statistical side quite profitable.

This paper tries to give an overview of a fascinating area. In doing so we treat more extensively problems with some statistical appeal. This leads inevitably to some overlap with our own work.
A Risk-based Global Coordination System in a Distributed Product Development Environment for Collaborative Design, Part I, Framework
Authors: Qiu Yuming , Ge Ping , Yim Solomon C.
Published: November 2007

This is the first of a two-part paper introducing a risk-based global coordination system in a distributed environment for collaborative design. Part I presents the basic concepts and a theoretical framework, and Part II describes the implementation and practical application to a National Science Foundation supported collaborative network. In a distributed environment, local negotiations within a stakeholder group (intra-stakeholder) and global negotiations among stakeholders (inter-stakeholder) co-exist. Strategic support is necessary to facilitate the integrative negotiation at the both intra- and inter- levels for effective distributed decision making. The challenge is that the distributed stakeholders have different subjective risk perceptions, interpretations and evaluations, which can be inconsistent and incoherent from a global perspective, and thus create considerable barriers for effective negotiation and coordination. Our approach is to (1) understand and capture heterogeneous risk evaluations at intra- and inter-levels, (2) represent and quantify all participants' subjective risk evaluations using a uniform structure, and (3) facilitate the negotiations through a risk-based coordination mechanism designed to achieve a globally consistent risk assessment (building consensus). The long-term goal of this work is to achieve a more fundamental understanding and develop useful tools for effective collaborative design.
A Risk-based Global Coordination System in a Distributed Product Development Environment for Collaborative Design, Part II, Application
Authors: Qiu Yuming , Ge Ping , Yim Solomon C.
Published: November 2007

This is the second of a two-part paper introducing a risk-based global coordination system in a distributed environment for collaborative design. Part I represents the basic concepts and a theoretical framework, and this paper describes a practical application in a National Science Foundation/George E. Brown, Jr Network for Earthquake Engineering Simulation. Core concepts, theoretical framework, and methodology developed in Part I are demonstrated through a collaborative design project. When an experiment is to be conducted, multiple stakeholders distributed at different geographical locations are required to work together, to achieve a desired experimental design, both individually and as a group, regardless of personal preference. A risk-based global coordination mechanism with a local risk assessment approach provides a quantitative base for negotiation and coordination among multiple, distributed stakeholders. The case study shows that globally consistent, quantitative risk analysis with considerations of all stakeholders' assessments provides a basis for them to understand each other better and help build up consensus for success of the collaborative design project.
Human Carcinogenesis, the New Genetics, and the Practicing Pathologist
Authors: Murphy William M.
Published: November 2007

The current explosion in medical information has broadened the range of op portunities for anatomic pathologists while threatening their identity as medical consultants. As the complexities of processes such as human carcinogenesis are clarified, the temptation to bypass traditional methods of transferring informa tion from the research bench to the bedside should be resisted. Patients continue to expect wisdom, perspective, and judgment from their doctors and these func tions have not been abrogated by molecular technology in the information age. Int J Surg Pathol 10(1):1-5, 2002
Prevalence of RET/PTC Rearrangements in Hashimoto's Thyroiditis and Papillary Thyroid Carcinomas
Authors: Nikiforova Marina N. , Caudill Christy M. , Biddinger Paul , Nikiforov Yuri E.
Published: November 2007

The relationship between Hashimoto's thyroiditis (HT) and follicular cell-derived thy roid cancer remains unclear. Recently, 2 studies reported a 95% prevalence of RET/PTC rearrangements in histologically benign tissue affected by HT, suggesting that multiple occult tumors exist in HT patients with high frequency. We tested the prevalence of RET/PTC rearrangements in 26 HT, in 6 papillary carcinomas arising in the background of HT, and in 27 papillary carcinomas not associated with HT. We detected no RET/PTC rearrangements in HT or papillary carcinomas arising in the background of HT, in contrast to a 33% prevalence among papillary carcinomas not associated with HT. However, the expression of wild-type RET was found in more than half of papillary carcinomas. These results suggest that, if the association be tween HT and thyroid cancer exists, its molecular basis is different from RETIPTC rearrangement. Int J Surg Pathol 10(1):15-22, 2002
Testicular Seminoma: A Clinicopathologic and Immunohistochemical Study of 105 Cases with Special Reference to Seminomas with Atypical Features
Authors: Tickoo Satish K. , Hutchinson Brian , Bacik Jennifer , Mazumdar Madhu , Motzer Robert J. , Bajorin Dean F. , Bosl George J. , Reuter Victor E.
Published: November 2007

In spite of the high curability rates, rare cases of testicular seminoma behave in an unexpectedly aggressive manner. No effective markers are currently available that can predict such uncommon behavior. We studied 105 cases of testicular seminoma on whom the primary resection was performed at the Memorial Sloan-Kettering Cancer Center, New York, to investigate any relationship between morphology, im munohistochemical features, and clinical/pathological stages. Fifty-nine percent of the cases presented with pT stage 1 and 74 percent with American Joint Committee on Cancer (AJCC) stage I. In univariate analysis, tumor size, mitotic count, and pres ence of necrosis showed significant associations with pT stage (p = 0.0001, 0.0001, and 0.04, respectively), and the presence of vascular invasion (p = 0.0001, 0.0001, and 0.02, respectively). In multivariate analysis, both the tumor size and mitotic counts were independent predictors of pT stage (p = 0.0004 and 0.0001) and vascu lar invasion (p = 0.0004 and 0.0001). When tumors were separated on the basis of architectural and/or cytological atypia into 'usual seminomas' and 'seminomas with atypia,' these were significantly associated with AJCC stage (p = 0.02), and c-kit pro tein (p = 0.0005) and CD30 expression ( p = 0.02). In addition, 'seminomas with atypia' also tended to show a higher proliferation activity as judged by Ki67 reactiv ity (p = 0.06), as well as express the marker of epithelial differentiation, Cam 5.2 (p = 0.09). In summary, we find that the morphologic features in testicular semi nomas are associated with factors of clinical relevance. Also, 'seminomas with atypia' differ from 'usual seminomas' morphologically, present at a higher AJCC stage, and possibly represent an early step in transformation of seminomas toward a more aggressive phenotype. While not proposing a new entity, we suggest that when these atypical features are encountered in an otherwise classical seminoma, investigations must be performed to exclude an early carcinomatous differentiation or even earlier changes toward such a differentiation, such as lack of c-kit protein expression. Int J Surg Pathol 10(1):23-32, 2002
Proliferation Kinetics of Non-Hodgkin's Lymphoma
Authors: Opitz Lynne M. , Vamvakas Eleftherios C. , Espiritu Edith C. , Fineberg Susan A. , Feiner Helen
Published: November 2007

The growth fractions of 35 non-Hodgkin's lymphomas (NHL), classified according to the International Working Formulation (IWF) as low, intermediate, or high grade, and 7 lymphoid hyperplasias were analyzed. The assays used were: (1) Ki67 antigen expression using a monoclonal anti-Ki67 antibody and indirect immunofluorescence microscopy on cytocentrifuge slide preparations (%Ki67); (2) flow cytometric assay of incorporated bromodeoxyrudine (BrDU) during short-term cell culture with a fluo rescein-labeled anti-BrDU antibody (%BrDU); and (3) flow cytometric cell cycle analy sis following propidium iodide incorporation (%S-PI). When the results obtained by these three methods were analyzed according to IWF histologic/prognostic groups, a consistent trend was seen: the values obtained increased with increasing tumor grade, and all three methods could discriminate low- from high-grade NHL. Additionally, %Ki67 and %BrDU discriminated between intermediate- and high-grade NHL. None of the methods discriminated between NHL of low and intermediate grades or between such lymphomas and lymphoid hyperplasia. Multivariate discriminant analysis using a panel consisting of the variables %Ki67, %BrDU, and %S-PI could distinguish between high-grade NHL and all other NHL, as well as between high-grade and intermediate- grade NHL, greater than 90% of the time. In the analyses that resulted in significant discriminant functions, %Ki67 had the best statistically determined discriminatory ability of the three methods. The correlation between cell cycle kinetics and IWF grade suggests that such measurements may have prognostic significance. Int J Surg Pathol 1(1): 33-42, 1993
Pediatric Anaplastic Large Cell (CD30+) Lymphomas Associated With the t(2;5) (p23;q35) Chromosomal Abnormality
Authors: Smith Nicholas M. , Byard Roger W. , Vasiliou Maria , Callen David F. , Bourne Anthony J. , Leong Anthony S.-Y.
Published: November 2007

Translocation of genetic material from the short arm of chromosome 2 to the long arm of chromosome 5, t(2;5)(p23;q35), has been associated with so-called histiocytic malignancies, with large T-cell lymphoma in childhood and with CD30+ (Ki-1) lym phoma. In an attempt to clarify the relationship between the t(2;5)(p23;q35) abnor mality and tumors in the pediatric age group, three cases of t(2;5)(p23;q35) from the files of the Adelaide Children's Hospital were accessed and clinical and histological data were reviewed. All cases had been originally diagnosed as hematolymphoid tumors. Histologically, the tumors were anaplastic large cell lymphomas, two of pleomorphic and one of monomorphic subtype. When immunohistochemistry was performed, all three were positive for CD30, characteristic of Ki-1 lymphoma. Two were positive for epithelial membrane antigen, all were positive for at least one T-cell marker, and all were negative for histiocytic markers. The monomorphic tumor recurred on several occasions, but the worst outcome occurred in one of the pleomorphic tumors, which proved fatal within 6 months. The precise significance of the breakpoints at 2p23 and 5q35 is not known, although it is not thought to be related to the proximity of the c-fms proto-oncogene, the colony stimulating factor 1 gene, or the N- myc proto-onco gene. The uniformity of the chromosomal abnormality contrasts with the variability of tumor morphology and clinical outcome. Close follow-up evaluation of current cases will be necessary to enable further characterization of this heterogeneous group of lymphoid tumors. Int J Surg Pathol 1 (1): 43-50, 1993
Diffuse Histiocytic Proliferation Mimicking Mesothelial Hyperplasia in Endocervicosis of the Female Pelvic Peritoneum
Authors: Ruffolo Robert , Suster Saul
Published: November 2007

Two cases of a diffuse histiocytic proliferation that mimicked mesothelial hyperplasia in the pelvic peritoneum of premenopausal women with endocervicosis are presented. The lesions were found incidentally on laparoscopic examination for pelvic pain and appeared as small friable excrescenses attached to the serosal surface of the pelvis. Histologic examination revealed a dense proliferation of round to oval cells with abun dant eosinophilic cytoplasm and large, hyperchromatic nuclei showing focal invagina tions and occasional mitoses. The cells appeared to infiltrate the surrounding connec tive tissue in single files and were closely associated with sloughed strands of small, cuboidal mesothelial cells as well as with larger glands lined by mucinous epithelium. Immunohistochemical studies showed cytoplasmic staining of these cells with MAC387, HAM56, and alpha-1-antichymotrypsin antibodies, thus supporting their histiocytic nature. The close association of the histiocytic proliferation with the endo cervicotic glands raises the possibility that the process may have resulted as a reaction to rupture and extrusion of the mucous contents of the glands into the surrounding stroma. These lesions must be distinguished from reactive or neoplastic mesothelial proliferations involving the female pelvic peritoneum. Int J Surg Pathol 1(2):101-106, 1993
Sarcomatoid Renal Cell Carcinoma
Authors: Kragel Peter J. , Walther McClellan M. , Pestaner Joseph P. , Merino Maria J.
Published: November 2007

Histologically, the sarcomatoid variant of renal cell carcinoma (SRCC) is a pleomorphic spindle or giant cell malignancy resembling a sarcoma. Clinically, SRCC is associated with a worse prognosis than common renal cell carcinoma (CRCC) of clear or granular cell types. The authors reviewed the clinical and pathologic findings in five cases of SRCC and performed avidin-biotin peroxidase staining with Leu-M1 and biotinylated lotus tetragonolobus lectin, which react with proximal tubules, biotinylated soybean and dolichos biflorus agglutinins, which react with distal tubules, cytokeratin AE 1, epithelial membrane antigen, and vimentin. Five of five SRCCs reacted with at least one marker of proximal tubular differentiation. No case reacted with distal tubular differentiation markers. Three of five cases were cytokeratin positive, one of five was epithelial membrane antigen positive, and zero of five were vimentin positive. Since most cases of CRCC react with proximal tubular markers, these findings suggest that SRCC is a histologic subtype of CRCC rather than a distinct histogenetic entity. Int J Surg Pathol 1 (2):107-110, 1993
In Situ Hybridization and Immunocytochemical Evidence Supporting a Cartilaginous Origin
Authors: Hicks David G. , Krasinskas Alyssa M. , Sickel Joshua Z. , Hughes Steve S. , Puzas J. Edward , Moynes Robin , Rosier Randy N.
Published: November 2007

Chondroblastoma is a rare benign epiphyseal lesion of bone. Previous immunocyto chemical studies have shown a pattern of staining similar to normal cartilage. The authors studied five cases of chondroblastoma by in situ hybridization and immunocy tochemical methods to further characterize these lesions. In situ hybridization, using a digoxigenated oligonucleotide cDNA probe, demonstrated type 2 collagen mRNA in mononuclear stromal cells, especially in areas of matrix formation. Immunocytochem istry demonstrated variable staining with epithelial and neural markers, as well as a scattered population of stromal cells that stained with histiocytic markers. The demon stration of type 2 collagen mRNA in this lesion supports a cartilaginous origin. The presence of histiocytic cells within the stroma most likely represents a reactive compo nent to the lesion. The results of this study provide immunocytochemical and molecu lar evidence supporting a cartilaginous origin for this benign neoplasm. Int J Surg Pathol 1 (3):155-162, 1994
HMB-45 Staining in Angiomyolipoma, Cardiac Rhabdomyoma, Other Mesenchymal Processes, and Tuberous Sclerosis-associated Brain Lesions
Authors: Weeks Douglas A. , Chase Donald R. , Malott Richelle L. , Chase Resa L. , Zuppan Craig W. , Beckwith J. Bruce , Mierau Gary W.
Published: November 2007

HMB-45 monoclonal antibody is thought to be highly specific for melanocytic prolifer ations. In a recent study of two cases of hepatic and one case of renal angiomyolipoma, strong staining of lesional cells with this antibody was unexpectedly encountered. In follow-up evaluation, the authors studied 51 additional soft tissue, renal, and brain tumors and tumor-like processes, with emphasis on those with prominent vascular, myogenous, and fatty components or those known to be associated with tuberous sclerosis. Varying degrees of staining with HMB-45 were seen in 17 of the lesions tested. Strong staining with HMB-45 was demonstrated in four renal angiomyolipo mas. Clearly positive results were also obtained in three other processes associated with the tuberous sclerosis complex, including two cardiac rhabdomyomas and one tuberous lesion of the brain. Weak staining of several other mesenchymal and neural lesions was also observed. Electron microscopic studies showed a spectrum of granules within angiomyolipoma, some of which resembled melanosomes and others renin granules. Similar granules were observed in cardiac rhabdomyoma, cerebral tuberous lesions, and in subependymal giant cell astrocytoma. We propose that tuberous scleros is-associated tumors and tumor-like processes are interrelated, and that these and perhaps other mesenchymal proliferations may share components previously believed to be unique to melanocytic lesions. Int J Surg Pathol 1 (3):191-198, 1994
Leiomyosarcoma of the Anus
Authors: Ueyama Toshihiko , Hashimoto Hiroshi , Tsuneyoshi Masazumi
Published: November 2007

Six cases of leiomyosarcoma arising in the anus were analyzed both clinicopathologi cally and immunohistochemically. All patients were women, and the mean age was 57 years. The tumors were classified according to the predominant histologic features: two were well and four were moderately differentiated. No poorly differentiated or dedifferentiated areas were recognized. Epithelioid features were seen in parts of all cases. The number of mitoses per 10 high-power fields (HPF) ( x 400) were 1 and 2 in one case each and 4-9 in four cases. Immunohistochemically, all the tumors were positive for muscle-specific actin (HHF35). Alpha smooth muscle actin and desmin were positive in three and four cases, respectively. Two of the six cases died of the disease. Three of the four cases with high mitotic figures (four or more per 10 HPF) either died of the disease or had a local recurrence. These findings suggest that many anal leiomyosarcomas may immunohistochemically and histologically belong to the differentiated type, while the mitotic rate may be an important prognostic factor. Int J Surg Pathol 1(4):221-226, 1994
Malignant Myoepithelioma of Salivary Glands: Clinocopathologic and Immunophenotypic Features
Authors: El-Mofty Samir K. , O'Leary Timothy R. , Swanson Paul E.
Published: November 2007

Malignant myoepithelioma is a rare salivary gland carcinoma that might be confused with other neoplastic lesions, including carcinoma and sarcoma. A review of 10 previ ously reported acceptable cases and 2 new ones shows that the tumor affects older individuals with a mean age of 60 years. The parotid gland was the site of tumor in eight cases and the minor salivary glands of the mouth in four. Microscopically, 9 of the 12 tumors were composed either partly or predominantly of spindle-shaped cells. Plasmacytoid cells were the second most common cell type, and round or epithelioid cells were the least common type. Immunohistochemical evidence of myoepithelial differentiation in 10 evaluated cases included positive staining with antibodies against cytokeratin, muscle specific actin, S 100 protein, and vimentin. Ultrastructural features of a myoepithelial phenotype in nine studied cases were cytoplasmic microfilaments with focal densities, desmosomal cell junctions, basal lamina, and hemidesmosomal junctional plaques. Because of a limited number of reported cases and a paucity of follow-up data, it is not possible at present to accurately predict the clinical course of malignant myoepithelioma of salivary glands. However, it appears that local recurrence is an important cause of treatment failure. Metastasis is infrequent. Int J Surg Pathol 2(2):133-140, 1994
Isolated Renal Mucormycosis Simulating a Renal Neoplasm in a Patient With the Acquired Immunodeficiency Syndrome
Authors: Remadi Sami , Rogiano Dora , Vassilakos Pierre , Seemayer Thomas A.
Published: November 2007

We report the case of a terminally ill patient with the acquired immunodeficiency syndrome who presented with a tender enlarged renal mass that simulated a renal neoplasm. A needle biopsy of the kidney revealed ischemic necrosis, vascular destruc tion, and fungal forms consistent with infection by the Zygomycetes family. Subse quently, autopsy confirmed this diagnosis and established that the kidney was the sole site of this fungal infection. Since fungal infections of the kidney simulating a renal tumor have not previously been described in acquired immunodeficiency syndrome, this report expands the list of lesions produced by opportunistic infections arising in a setting of human immunodeficiency virus-induced immunosuppression. Int J Surg Pathol 2(2):163-168, 1994
Granulocytic Sarcoma
Authors: Goldstein Neal S. , Ritter Jon H. , Argenyi Zsolt B. , Wick Mark R.
Published: November 2007

Because of shared histologic and clinical features, granulocytic sarcoma (GS) may be confused with B- and T cell malignant lymphomas. Antibodies to myeloperoxidase, lysozyme, CD 15, and other determinants may correctly identify GS but are usually not part of the standard panels employed to evaluate a suspected non-Hodgkin's lym phoma. At the authors' institutions, these typically include reagents to CD20, CD43, CD45, CD45RO, and MB2. In this analysis, well-documented cases of GS and histologi cally similar lymphomas were assessed using a standard immunohistologic antibody panel employed in evaluation of putative lymphomas. In addition, antibodies to lyso zyme, myeloperoxidase, CD3, CD15, CD34, CD68, and MAC 387 were used in a second tier of analysis. The results were evaluated in a step-wise fashion. All B cell lymphomas and the majority of T cell cases were identified correctly by their reactivity for CD20 and CD45RO, respectively. Using the five standard lymphomas markers, 12 of 19 cases of GS had a phenotype that would be relatively unusual in non-Hodgkin's lymphoma—as reflected by CD43 and MB2 coexpression without CD20 or CD45RO-whereas 7 cases of GS showed a "CD43-only" phenotype and were there fore considered possible T cell lesions. All 19 GS cases were labeled by at least one second-tier marker and 18 exhibited two or more of these determinants at that level of evaluation. All T cell lymphomas failed to express CD 15, CD34, CD68, or MAC 387; however, 3 of 20 B cell tumors were focally positive for CD 15. CD3 labeled 9 of 11 cases of T cell lymphoma but also was seen in 11 of 16 cases of GS. These results indicate that, in suspected lymphoma cases, CD45-positivity, but failure to express CD20 or CD45RO, suggests the possibility of GS. Additional immunohistologic studies, in particular those for lysozyme or myeloperoxidase, can then be used to further define the tumoral lineage. Int J Surg Pathol 2(3):177-186, 1995