Lack Of Interchangeability Research Articles

D-dimer-An International Assessment of the Quality of Laboratory Testing: Implications for D-dimer Use in the Real World.

D-dimer assessment has several established roles in venous thromboembolism (VTE) and disseminated intravascular coagulation diagnosis, and recently the risk stratification of coronavirus disease 2019 (COVID-19). D-dimer assays are neither standardized nor harmonized, use varying methodologies, and use different reporting units, all resulting in a lack of interchangeability and generalizability of assays. Using large multiyear datasets from an international laboratory quality assurance program, we assessed (1) common D-dimer assays in use worldwide, (2) differences in analytical performance between different methods, and (3) interlaboratory variability between positive samples. External proficiency testing results from laboratories participating in the External Quality Control for Assays and Tests (ECAT) Foundation were analyzed from 2017 to 2023. Annually, between 578 and 690 laboratories participated in the D-dimer sample surveys with response rates ranging from 88 to 97%. The three most common assays in use in 2023 were the Siemens Innovance D-dimer (42%), the IL HemosIL D-dimer HS 500 (20%), and the Diagnostica Stago (Stago) Liatest D-dimer Plus (10%)-all these are automated, quantitative, latex immunoassays expressed in fibrinogen equivalent units (FEU). The highest interlaboratory variability was observed around the typical VTE exclusion threshold of 0.5 mg/L FEU. Lower interlaboratory variability was observed at values above 0.8 mg/L FEU. Our study provides recent, international performance data on currently used D-dimer assays and describes the significant variability between assays and across D-dimer concentrations. We demonstrate that assays are not interchangeable and that using them interchangeably has the potential to result in clinically important errors. There is an urgent need to educate users about these issues and to work towards harmonizing D-dimer units and reporting.

Lack of Interchangeability Between 3 Different Methods for Quantification of Everolimus in Blood: ACMIA, LTIA, and UHPLC-MS/MS.

Affinity chrome-mediated immunoassays (ACMIA) do not require pretreatment and have a wide calibration range and good analytical performance. To date, no studies have compared ACMIA and latex agglutination turbidimetry immunoassays (LTIA). The objective of this study was to evaluate the interchangeability of ACMIA, LTIA, and the previously developed ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). A total of 111 whole blood samples were collected from 25 patients undergoing routine everolimus therapeutic drug monitoring. The interchangeability between the 3 methods was assessed using robust Passing-Bablok regression analysis and Bland-Altman plots. All samples were quantifiable by UHPLC-MS/MS, whereas 56 and 1 samples were below the lower limits of quantification by LTIA and ACMIA, respectively. In the robust Passing-Bablok regression plots, the slopes of the regression equations between ACMIA and UHPLC-MS/MS, LTIA and UHPLC-MS/MS, and ACMIA and LTIA were 1.23 (95% [confidence interval] CI, 1.13-1.33), 0.67 (95% CI, 0.57-0.77), and 1.71 (95% CI, 1.43-2.33), respectively, with significant proportional biases indicating no interchangeability among all 3 methods. Bland-Altman plots also revealed statistically significant proportional biases between ACMIA and UHPLC-MS/MS (P = 0.012), LTIA and UHPLC-MS/MS (P < 0.001), and ACMIA and LTIA (P < 0.001). Statistically significant proportional biases were observed among the 3 methods. Blood everolimus concentration measurements should be interpreted with caution when switching the quantification methods for therapeutic drug monitoring.

Bridging event-related potentials with behavioral studies in motor learning.

Behavioral approaches and electrophysiology in understanding human sensorimotor systems have both yielded substantial advancements in past decades. In fact, behavioral neuroscientists have found that motor learning involves the two distinct processes of the implicit and the explicit. Separately, they have also distinguished two kinds of errors that drive motor learning: sensory prediction error and task error. Scientists in electrophysiology, in addition, have discovered two motor-related, event-related potentials (ERPs): error-related negativity (ERN), and feedback-related negativity (FRN). However, there has been a lack of interchange between the two lines of research. This article, therefore, will survey through the literature in both directions, attempting to establish a bridge between these two fruitful lines of research.

Consistency and diagnostic accuracy of 4 assays in the detection of the total and free prostate-specific antigen.

The lack of interchangeability among prostate-specific antigen (PSA) assays causes difficulties in clinical interpretation. The currently available mainstream assays for PSA were based on Western populations, but it is not clear whether these assays yield different results in prostate cancer (PCa) screening in Chinese populations. A total of 163 men with a total PSA (tPSA) level of 2-10 µg/L scheduled for prostate biopsy were enrolled in this study. The levels of the tPSA and free PSA (fPSA) were detected by the Beckman (using the Hybritech calibration), Roche, Abbott, and Mindray (using the World Health Organization's calibration). Methodological comparison were performed according to EP9-A3 of the Clinical and Laboratory Standards Institute, USA. With pathological diagnosis as the gold standard, the predictive accuracy of the biomarkers was quantified as the area under the receiver operating characteristic curve (AUC) for each of the four methods. A total of 32 PCa patients and 131 patients with benign prostate disease were included in this study. The tPSA levels detected by the Roche, Abbott, and Mindray showed good consistency with Beckman but not of the fPSA levels. Compared to the Beckman tPSA values, the measured values were 1.1% higher for Roche, 2.1% higher for Abbott, and 6.7% higher for Mindray. The fPSA levels measured by Roche, Abbott, and Mindray were 5.4% lower, 22.1% higher, and 4.6% higher than Beckman, respectively. When the tPSA was 4 ng/mL, the diagnostic performance (sensitivity, specificity, positive predictive value, negative predictive value, and missed diagnosis rate) was similar among these 4 assays. When the %fPSA was 16%, Abbott had the highest missed diagnosis rate (37.50%), while Mindray had a sensitivity of 81.25%, the highest negative predictive value (93.88%), and the lowest missed diagnosis rate (18.75%). When the tPSA level is 2-10 ng/mL, the Mindray, like the Roche and Abbott, has good consistency with the Beckman in detecting tPSA, which makes it possible to relieve the pressure of clinical interpretation. However, 4 assays using the same %fPSA cut-off may lead to diverse missed diagnosis rates for PCa screening in China.

Complementary and alternative therapies in the palliative setting.

Complementary and alternative medicine (CAM) encompasses a wide range of medication, herbal, dietary and physical therapies that are not usually considered within the realm of conventional therapeutics. Approximately two thirds of the Australian population use CAMs and only around half of this number will discuss their use of these products with their doctor. Clinical use is commonly seen in patients with life-limiting illness, often because they experience a high burden of symptoms. However, it is also the case that many of these therapies do not have demonstrated efficacy, particularly for the often broad list of conditions and symptoms for which they are chosen to be used. Further, depending on whether they are sold as medications, sold as food supplements or imported illegally and distributed via nonstandard therapeutic channels, several products have had reports of toxicity, severe adverse effects, batch irregularities and drug interactions with other therapies. This awareness, together with lack of standardisation of products and lack of interchangeability between brands has made prescribers unwilling to put patients at risk of harm by supporting their use. In this article, we cover general pharmacological principles around use of a small selection of chemicals used in a medical setting to enable some guidance for use.

Comparing critical speed modelling approaches and exploring relationships with match-play variables in elite male youth soccer players.

A novel bi-exponential method has emerged to estimate critical speed (CS) and D-prime (D') from a 3-min all-out test (3MT). To compare CS analysis methods to determine whether parameter estimations were interchangeable. Reference values and relationships with key soccer match-play variables were explored. Thirteen elite male youth (14-15 years old) players completed a 30 m shuttle run 3MT to estimate CS, D', rate of speed decline time constant, maximal speed (S max), time to S max (t max), and fatigue index (FI), using the traditional method and bi-exponential model on average (Bi-ExpAverage) and max speed settings (Bi-ExpMax-Speed). High-speed running (HSR) and sprinting distances and counts, and the number of accelerations were collected from two matches. Magnitude-based inferences (p < 0.05) with smallest worthwhile change of 0.2 effect sizes were used to analyse differences. Pearson's and Spearman's correlation coefficients were used to measure associations between CS model variables and match-play parameters. There were significant differences between the traditional method and both bi-exponential models for CS and D', as well as between the bi-exponential models for all variables except t max. Using the Bi-ExpAverage model, strong correlations (r = 0.70-0.73; p < 0.05) were observed for D' and FI with the number of standardised and individualised HSRs, respectively. With the Bi-ExpMax-Speed model, there were strong correlations (r/ρ = 0.64-0.68; p < 0.05) between D' and the number of standardised HSRs and sprints, and the number of individualised sprints. There is a lack of interchangeability between analysis methods. It appears that D' and FI from the bi-exponential models could be associated with high-intensity actions in soccer match-play.

WAIS-IV short form applied to a mixed neurological Swedish clinical sample

The Wechsler Adult Intelligence Scale, fourth version (WAIS-IV), is a frequently used instrument for neuropsychological assessment. The aim was to assess the degree of conformity between the Scandinavian adaptation of the WAIS-IV and a short form of this scale (SF) in a mixed sample of neurological diagnoses. The SF comprised Block Design, Similarities, Digit Span, Arithmetic, Information, Digit Symbol (in the WAIS-IV named Coding), and Picture Completion, the latter here replaced by Matrix Reasoning. The sample consisted of 150 patients and included multiple sclerosis (n = 27), brain tumor (n = 15), traumatic brain injury (n = 60) and vascular brain damage (n = 48). There was a lack of congruence between the WAIS-IV and the SF in the entire sample, revealing selectively significantly higher scores for the SF on Full Scale IQ (FSIQ) and Processing Speed Index (PSI). On a diagnostic group level, the discrepancies were as follows: in the traumatic brain injury group on FSIQ, Verbal Comprehension Index (VCI) and PSI, in the vascular damage group the FSIQ was significantly higher on SF compared to the WAIS-IV. Since the results revealed several mismatches between the SF and the WAIS-IV, except for the MS and traumatic brain tumor group, there is a lack of interchangeability between these two sets of tests. Thus, generally the SF cannot be recommended as a substitute for the WAIS-IV in this type of mixed Swedish neurological sample. The small sample sizes make the generalizability of this study limited.

Determining the interchangeability of KaVo PROTAR semi-adjustable articulators.

Interchangeable articulators are crucial for a precise clinical outcome. Lack of interchangeability will affect the accuracy of the occlusion of prosthetic restorations. The objective of this study was to evaluate the interchangeability of KaVo PROTARevo articulators. KaVo PROTARevo semi-adjustable articulators in routine use were employed. Identical casts were transferred among the articulators and the distance between casts was measured using digital photos of sagittal and frontal aspects of each articulator by two independent examiners. Interchangeability was assessed and analyzed by designated software. Inter-examiner reliability was found to be high. Of 231 possible pairs of articulators only 27 pairs were found to be interchangeable (less than 166 µm in all measured dimensions), and of the other 204 pairs of articulators at least one of the dimensions measured was larger than 166 µm. The majority of articulators tested did not pass the 166-µm criterion to establish them as interchangeable. Therefore, in order to maintain accuracy while producing restorations, it is advisable to use the same articulator throughout the entire process, both at the clinic and in the dental laboratory.

Features and procedures of a unified and unabridged Korean dictionary, Gyeoremal-keunsajeon

Language is an integral part of what constitutes the culture and identity of a given society, interacting with various sociocultural, political and economic aspects of the society. In this respect, a particular language system is a whole complex reflective of multiple facets of the society and should be situated within a dynamic social framework. Likewise, language and related system and policy are social constructs, which can be exemplified by South and North Korea who originally shared the same language heritage, but have been showing increasing discrepancy in language, orthography and everyday words as a result of different social and ideological systems that divided two Koreas in the first place. Rather than moving forward in a direction of closing the gaps between two Koreas, lack of interchange and hostile relations in recent years are further deepening their differences. Despite this challenging circumstance, two Koreas have been engaging in various meaningful communication for the ultimate goal of reunification. A Unified and Unabridged Korean Dictionary is part of these efforts that seeks to resolve language differences between two Koreas through compiling the first unified and unabridged Korean dictionary. Through collaborative works between lexicographers from South and North Korea, the dictionary seeks to close language gaps between two Koreas and, ultimately, to provide a basis for a long-term goal of reunification. This paper explores defining features, procedures and present status of A Unified and Unabridged Korean Dictionary. Especially, the paper closely examines the principles behind the selection of entry words, description of entry words and microstructure of the dictionary.

Reproducibility of coffee quality cupping scores delivered by cupping centers in Ethiopia

AbstractThe reproducibility of cupping scores for 30 coffee samples from eastern, southern and southwestern origins in Ethiopia was evaluated by comparing absolute differences within and between nine cuppers, three Ethiopia Commodity Exchange (ECX) cupping centers (Jimma, Awassa, Dire Dawa) and three coffee origins. Additionally, the correlation between cupping scores of an exporter (ECX) and an importer (EFICO Agency SA) was evaluated based on 70 coffee samples from five different origins. Differences in ECX cupping score variability were generally observed for all studied quality attributes. Variability was higher between than within cuppers. Furthermore, particular high variable scores were observed for the Dire Dawa cupping center and for some attributes of the southwestern coffee origin. However, the average absolute difference for total cup quality was small (ca. 3 on a 100 scale), which indicates that cupping scores by the ECX are sufficiently reproducible to allow reliable coffee quality grading. However, no correlation was observed between cupping scores of the exporter and importer, which indicates a lack of interchangeability between grading data produced by both actors.Practical applicationsTesting and grading of the quality of green coffee beans by the Ethiopia Commodity Exchange cupping centers is fairly reliable. However, the exporter quality scores and grades can most likely not be used interchangeably with those of an importer.

A Second Dystopia in Education: Validity Issues in Authentic Assessment Practices

Authentic assessments used in response to accountability demands in higher education face at least two threats to validity. First, a lack of interchangeability between assessment tasks introduces bias when using aggregate-based scores at an institutional level. Second, reliance on written products to capture constructs such as critical thinking (CT) may introduce construct-irrelevant variance if score variance reflects written communication (WC) skill as well as variation in the construct of interest. Two studies investigated these threats to validity. Student written responses to faculty in-class assignments were sampled from general education courses within an institution. Faculty raters trained to use a common rubric than rated the students’ written papers. The first study used hierarchical linear modeling to estimate the magnitude of between-assignment variance in CT scores among 343 student-written papers nested within 18 assignments. About 18 % of the total CT variance was attributed to differences in average CT scores indicating that assignments were not interchangeable. Approximately 47 % of this between-assignment variance was predicted by the extent to which the assignments requested students to demonstrate their own perspective. Thus aggregating CT scores across students and assignments could bias the scores up or down depending on the characteristics of the assignments, particularly perspective-taking. The second study used exploratory factor analysis and squared partial correlations to estimate the magnitude of construct-irrelevant variance in CT scores. Student papers were rated for CT by one group of faculty and for WC by a different group of faculty. Nearly 25 % of the variance in CT scores was attributed to differences in WC scores. Score-based interpretations of CT may need to be delimited if observations are solely obtained through written products. Both studies imply a need to gather additional validity evidence in authentic assessment practices before this strategy is widely adopted among institutions of higher education. Authors also address misconceptions about standardization in authentic assessment practices.

Management and Treatment of Type 1 And 2 Diabetes: State of Art

Background: Diabetes is a hormonal disorder that affects an estimated three hundred million people worldwide. In this review (meta-analysis) of the literature, we carefully analyzed the limits and methods of the management of diabetes in adolescents and adults. Objective: The study focused on the identification of technologies and therapeutic procedures currently used and tried to identify possible factors for future improvement. Methods: The literature review was carried out on search engines like: PubMed, ADA, Google Scholar and Google Patents. According to our search criteria, the selected articles were analyzed regarding evidence and critical issues reported by patients and clinicians. The results were then compared with the recalls of the U.S. Food and Drug Administration (FDA). Results: The currently in use drugs and the insulin infusion systems vary a lot and simultaneous develop of new technology adds to existing chaos. This study revealed possible areas for improvements both from a technological and a medical point of view. For instance: the multiple causes related to the different timing of insulin absorption according to the insertion site, the design of new algorithms focused on simplification of practical activities, and the identification of new methods for training patients and families on the different device’s functions. Moreover, some critical points were emerged related to the current limitations and lack of interchangeability between sensors for monitoring vital parameters. This condition restricts the correct sensor selection according to the patient’s personal preference, age and needs. However, the lack of interchangeability between different devices limits the choice of the most appropriate monitoring software and data storage. Conclusions: The collaboration between medical doctors and biomedical engineers is of great importance when analyzing available medical devices for the purpose, identifies possible weaknesses, technical problems, and areas for improvements. Moreover, multi-specialist collaboration is important to conceive new methods of training for patients and families.

Biosimilars: Challenges and path forward

Development of biosimilar proteins is the fastest growing sector in the biopharmaceutical industry, as patents for the top 10 best-selling biologics will expire within one decade. The world’s first biosimilar of infliximab, Remsima® (CT-P13) made by Celltrion, was approved by the Committee for Medicinal Products for Human Use (CHMP) of European Medicine Agency (EMA) in June 2013. This has ignited competition between related companies for prior occupation of the global market on blockbuster biologics. However, to achieve approval for biosimilars, developing companies face many hurdles in process development, manufacturing, analysis, clinical trials, and CMC (chemical, manufacturing and controls) documentation. Recent evolutionary progress in science, engineering, and process technology throughout the biopharmaceutical industry supports to show similarity between originator and biosimilar products. The totality of evidence has been able to demonstrate the quality, efficacy, and safety of biosimilars whereas a lack of interchangeability and international standards has to be addressed. Further understanding of the timing importance by regulatory agencies will be key to maximizing the value of biosimilars.

A Single, Global Patient‐Centered Measure from the SF‐36 Instrument to Assess Surgical Outcomes and Quality of Life: A Pilot Study

Many quality of life (QoL) and patient-reported outcomes (PRO) measures have been developed to assess the effects of disease processes and treatments. Although these instruments are valuable, the process is hampered because of their number and lack of interchangeability. We identified a cohort of patients across a variety of operations within 3-12 months postoperatively. Patients completed the SF-36, measuring eight domains of QoL (physical functioning, role-physical, role-emotional, bodily pain, vitality, mental health, social functioning, and general health), plus a health transition item: Compared to one year ago, how would you rate your health in general now?. (1) Much better now than one year ago. (2) Somewhat better now than one year ago. (3) About the same as one year ago. (4) Somewhat worse than one year ago. (5) Much worse than one year ago. Additional data included improvement of preoperative symptoms, the occurrence of any postoperative symptoms, and the occurrence of any postoperative complications. Of 217 patients, 28 % were much better, 28 % somewhat better, 27 % unchanged, 13 % somewhat worse, and 3 % much worse. The health transition results were associated with all SF-36 domains, preoperative symptom change (p = 0.03) and persistent or new postoperative symptoms (p = 0.001), but not postoperative complications. Patients with persistent or new symptoms postoperatively had worse scores in the role-emotional (p = 0.01), bodily pain (p = 0.05), social functioning (p = 0.02), and mental health (p = 0.009) domains of the SF-36. This single, global assessment of health transition may be a promising practical alternative to assess postoperative patient-centered outcomes. Improved patients had better QoL scores, preoperative symptoms elimination, and no operation-related symptoms, but the occurrence of complications did not affect improvement.

Patient Safety and Clinical Effectiveness as Imperatives for Achieving Harmonization inside and outside the Clinical Laboratory

For clinical laboratorians, the case for standardization and harmonization has been evident for more than 4 decades, since Radin first proposed using traceable reference standards for calibration as a means to harmonize laboratory results produced with different in vitro diagnostic methods (1). Over the intervening period, the subject has been reviewed (2) and debated extensively—both inside and outside the laboratory community—yet a striking majority of our physician and surgeon colleagues still fail to grasp or understand the limitations of current laboratory measurements, the lack of interchangeability of results obtained by different analytical methods, and the resulting effects on interpretation, clinical decision-making, and patient management. Some incremental progress has been made in addressing these issues through professional organizations, multidisciplinary practice guidelines developed by national and international committees, peer-review publications, and the global in vitro diagnostic manufacturing industry. Notable successes include the National Glycohemoglobin Standardization Program (including the recommendations of the Diabetes Control and Complications Trial), the National Cholesterol Education Program, and the National Kidney Disease Education Program, which have helped drive improvements in laboratory methods for hemoglobin A1c, total cholesterol, and creatinine, respectively, and helped establish clinical practice guidelines based on laboratory measurements that meet defined performance criteria. As recently as October 2010, the AACC hosted an international conference for a diverse group of stakeholders to improve harmonization of laboratory results and to make recommendations for the future. Regrettably, personnel in the clinical laboratory must continue to cope on a day-to-day basis with the blissful ignorance or blatant denial of these multifactorial methodologic differences by many practicing clinicians and, sadly, a few fellow laboratory colleagues. Harmonization of results remains the “holy grail.” How often have we been asked, “Isn't one test result the same as another from a different laboratory?” Even after careful explanation and intensive efforts to educate, …

On the limited interchangeability of rule of law measures

During the latest decade, empirical research on the causes and consequences of the rule of law has expanded and, in the process, become extremely influential. However, we show that a number of widely used indices of the rule of law are not interchangeable. This lack of interchangeability is reflected in the fact that they are based on different defining attributes, to some extent cover distinct empirical scopes, do not correlate highly with each other, and support different explanatory factors. Until a consensus has been established with respect to the conceptualization of the rule of law, scholars are thus not free to opt for the measure that fits their data requirements best regarding spatial and/or temporal scope. Instead, they must carefully assess the content validity vis-à-vis their stipulated definition of the rule of law. Given the amount of money and time poured into the rule of law agenda, the problems identified reflect the lack of maturity of ‘good governance’ research.

Lack of interchangeability between visual analogue and verbal rating pain scales: a cross sectional description of pain etiology groups

Background:Rating scales like the visual analogue scale, VAS, and the verbal rating scale, VRS, are often used for pain assessments both in clinical work and in research, despite the lack of a gold standard. Interchangeability of recorded pain intensity captured in the two scales has been discussed earlier, but not in conjunction with taking the influence of pain etiology into consideration.Methods:In this cross-sectional study, patients with their pain classified according to its etiology (chronic/idiopathic, nociceptive and neuropathic pain) were consecutively recruited for self-assessment of their actual pain intensity using a continuous VAS, 0–100, and a discrete five-category VRS. The data were analyzed with a non-parametric statistical method, suitable for comparison of scales with different numbers of response alternatives.Results:An overlapping of the VAS records relative the VRS categories was seen in all pain groups. Cut-off positions for the VAS records related to the VRS categories were found lower in patients with nociceptive pain relative patients suffering from chronic/idiopathic and neuropathic pain. When comparing the VAS records transformed into an equidistant five-category scale with the VRS records, systematic disagreements between the scales was shown in all groups. Furthermore, in the test-retest a low percentage of the patients agreed to the same pain level on the VAS while the opposite hold for the VRS.Conclusion:The pain intensity assessments on VAS and VRS are in this study, not interchangeable due to overlap of pain records between the two scales, systematic disagreements when comparing the two scales and a low percentage intra-scale agreement. Furthermore, the lower VAS cut-off positions relative the VRS labels indicate different meaning of the rated pain intensity depending on pain etiology. It is also indicated that the scales have non-linear properties and that the two scales probably have different interpretation. Our findings are in favor of using the VRS in pain intensity assessments but if still the VAS is preferred, the VAS data should be analyzed as continuous using statistical methods suitable for ordinal data. Furthermore, our findings indicate a risk to over or under estimate the patient's perceived pain when interpreting condensed VAS data.

The Birth of California Narrow Gauge: A Regional Study of the Technology of Thomas and Martin Carter (review)

Reviewed by: The Birth of California Narrow Gauge: A Regional Study of the Technology of Thomas and Martin Carter Carlos Schwantes (bio) The Birth of California Narrow Gauge: A Regional Study of the Technology of Thomas and Martin Carter. By Bruce MacGregor. Stanford, Calif: Stanford University Press, 2003. Pp. x+673. $79.95. One fascinating episode in the history of railroads is the battle of the gauges waged in Britain in the 1830s and 1840s, with the standard gauge of 4 feet 81/2 inches emerging victorious against Isambard Kingdom Brunel's massive 7-foot gauge. In the United States the quest for standardization took far longer and was much more complicated, especially in the South, where diverse gauges and lack of interchangeability between railroad cars proved a logistical nightmare for the Confederacy. But in the early 1870s, ironically, when standard-gauge tracks seemed likely to prevail over several different broad gauges in the United States, advocates of narrow-gauge common carriers sent the technological debate in a new direction. Narrow-gauge lines (most of those in the United States measured three feet between the rails) represented more than a passing fad. The technology had genuine appeal to railroaders seeking to extend lines through mountainous terrain in which standard-gauge track would be ruinously expensive or to construct low-cost connections, as Salinas Valley wheat farmers did when they extended a narrow-gauge line to tidewater at Monterey to undercut the Southern Pacific/Central Pacific rail monopoly. Another of Stanford University Press's substantial books—George Hilton's magisterial American Narrow-Gauge Railroads (1990)—exhaustively chronicles this technology. Perhaps for that reason, Bruce MacGregor says relatively little about the [End Page 208] gauge issue in general before plunging into his topic, a regional study of the construction and operation of narrow-gauge lines in California. The main focus is on the activities of the brothers Thomas and Martin Carter, who built several California narrow-gauge lines and supplied a substantial portion of their rolling stock. MacGregor argues that their situation was unusual in that California's physical isolation from major car builders, located primarily on the Atlantic Coast, gave local entrepreneurs a chance to prosper within the niche market for narrow-gauge technology. MacGregor's massive book seems to offer something for everyone, from railroad historians to model builders. In addition to the main text, it includes a wealth of illustrations—more than six hundred drawings and photographs—and sidebars on a wide variety of topics that strike MacGregor's fancy, everything from basic car anatomy to the making of a timetable. All of this information is nicely indexed. Yet, despite its wealth of detail, including a large number of historical maps, there are some surprisingly conspicuous omissions. Readers not familiar with California's geography and topography will yearn for at least one rail map of the entire state with the historical narrow-gauge lines properly located. The historical maps are a nice touch, but too often their details are not easy to read. Students of technology will find much of value in this book, especially MacGregor's description of the narrow-gauge railroad support structure, such as the Carter brothers' fabricating shop, or the practice of often sending cars to purchasers in kit form. However, I suspect that most purchasers of this book will use it mainly as a reference tool. Model builders and preservation-minded rail aficionados, for example, will find numerous detailed drawings of freight and passenger cars. The Birth of California Narrow Gauge is physically too big a book to take to bed for leisurely enjoyment. Nonetheless, it is truly a book as beautiful as it is comprehensive, and the author and publisher deserve praise for the impressive result of their collaboration. Carlos Schwantes Dr. Schwantes is St. Louis Mercantile Library Professor of Transportation and the West at the University of Missouri—St. Louis. Copyright © 2005 The Society for the History of Technology

Development of the North American Tertiary freshwater fish fauna with a look at parallel trends found in the European record

The Tertiary history of the North American freshwater fish fauna was summarized for comparison with the European fauna. Attention was paid to duration and extinction of taxa, appearance of new taxa, diversity at the generic level and evidence of interchange. For the purpose of comparison, the original Tertiary fauna was judged to be that developed and in place by middle Eocene time in both North America and Europe. The original faunas were quite distinct but had archaic elements in common from the Cretaceous or earliest Tertiary (Paleocene). In North America parts of the Oligocene and Miocene epochs were times of faunal transition and interchange. In reference to the Recent taxa, it was found that most fruitful comparisons could be made by a close look at the faunal components found within selected families like the Cyprinidae which have been studied cladistically. Both Europe and North America received their cyprinids from Asia beginning in the Oligocene. By the end of the Tertiary, cyprinids had evolved into a major segment of the freshwater biota in both areas. However, there was an almost complete lack of interchange between North America and Europe involving cyprinids or any of the other cypriniform families. What was most remarkable for the Tertiary faunas was the absence (with a few noteworthy exceptions) of shared taxa at the generic level. The Tertiary North American freshwater fish fauna had a significant relationship with Asia (probably through separate migrations across Beringia) during the Eocene, Oligocène, early Miocene, Pliocene and Pleistocene. Because the faunas of the two regions (North America and Europe) developed with a number of parallel trends (such as those illustrated by the Cyprinidae) they present a rich subject for discussion.

Endoscopic ultrasonography: current indications and applications.

Endoscopic ultrasonography is an exciting new field, with a rapidly expanding literature describing a wide variety of applications. Despite remarkable advances in the field, a number of crucial issues remain to be resolved. These include the limited availability of educational programs for training, enormous initial start up costs for centers related to the cost of equipment and the lack of interchangeability with processors, paucity of outcomes research studies, and technical limitations of the currently available devices. The aim of this article is to review the basic principles, instrumentation, applications, and potential problems related to endoscopic ultrasound and to attempt to define the realistic role for this tool in contemporary medical practice.