bluuebunny/crossref_metadata_2025 huggingface dataset:
Blue integumentary structural colours in dragonflies (Odonata) are not produced by incoherent Tyndall scattering
Authors: Prum Richard O. , Cole Jeff A. , Torres Rodolfo H.
Published: October 2004

For nearly 80 years, the non-iridescent, blue, integumentary structural colours of dragonflies and damselflies (Odonata) have been attributed to incoherent Tyndall or Rayleigh scattering. We investigated the production of the integumentary structural colours of a damselfly – the familiar bluet, Enallagma civile (Coenagrionidae) – and a dragonfly– the common green darner, Anax junius (Aeshnidae) –using fibre optic spectrophotometry and transmission electron microscopy(TEM). The reflectance spectra of both species showed discrete reflectance peaks of ∼30% reflectance at 475 and 460 nm, respectively. These structural colours are produced by light scattering from closely packed arrays of spheres in the endoplasmic reticulum of box-shaped epidermal pigment cells underlying the cuticle. The observed reflectance spectra do not conform to the inverse fourth power relationship predicted for Tyndall/Rayleigh scattering. Two-dimensional (2-D) Fourier analysis of the TEM images of the colour-producing arrays reveals ring-shaped distributions of Fourier power at intermediate spatial frequencies, documenting a quasiordered nanostructure. The nanostructured Fourier power spectra falsify the assumption of spatial independence of scatterers that is required for incoherent scattering. Radial averages of the Fourier power spectrum indicate that the spheres are substantially nanostructured at the appropriate spatial scale to produce visible colours by coherent scattering. However, the spatial periodicity of the arrays is apparently too large to produce the observed colour by coherent scattering. The nanospheres could have expanded substantially (∼50%)during preparation for TEM. Alternatively, coherent light scattering could be occurring both from the surfaces and from structures at the centre of the spheres. These arrays of colour-producing spheres within pigment cells have convergently evolved at least 11–14 times independently within the Odonata. Structural colouration from arrays in living cells has also fostered the convergent evolution of temperature-dependent colour change in numerous odonate lineages.
Laplace transform to avoid numerical instabilities due to the effect of Peclet number in thermal problems
Authors: Bou-Saïd B , Colin F , Kane M
Published: October 2004

It is well known that thermal analysis is important in tribology in both dry and lubricated cases. In lubricated contacts, the effect of temperature for high speeds and high loads governs the parameters that characterize the contact behaviour (frictional force, carrying capacity, flow, etc.). Thus the thermal analysis in the fluid and in the surrounding bodies is necessary to model the contact correctly. The finite element method (FEM) has proved in recent years to be one of the most general and useful procedures for prediction of the characteristics of lubricated contacts. However, where thermal effects are taken into account the method has limitations and can cause oscillations and inaccuracies to occur in solutions at high velocity (high Peclet number). For example, oscillations occur in the solutions for a 0.04m shaft running at 6r/min (Peclet number ≅ 9). Clearly, the range of velocity magnitudes that leads to good results with the FEM is unable to cover a broad range of industrial applications. Some remedies have already been suggested (smaller elements, hybrid formulation, the weighted residual method with a weighting function different from the interpolation function, etc.). An altogether different approach is to modify the initial equation.

It is well known that the oscillations and numerical instabilities arise from the fact that the thermal problem is not self-adjoint. The essential point, not usually stressed, concerns the symmetry of a linear operator (as for a matrix), which is not an absolute notion. It is relative to a bilinear form. If the given problem does not ensure this symmetry condition (as in the present case) an attempt may be made to transform the given problem into another that fulfils the symmetry conditions.

A method based on Gurtin's theorem is proposed here which allows a preliminary transformation of an equation into an integral-differential one and the convolution product of two functions. This method leads to a variational formulation of any linear initial value problems. Therefore, if the problem has a variational formulation the operator is symmetric and the stiffness matrix obtained from numerical discretization (here FEM) is also symmetric. When this is the case the effect of the Peclet number disappears. This method has been applied here to the thermal problem for slider and journal bearings and obtained very promising results in order to generalize this method to non-linear conditions in stationary thermal problems.
Turbulent thermohydrodynamic lubrication models compared with measurements
Authors: Tanaka M , Hatakenaka K
Published: October 2004

The authors derived a three-dimensional turbulent thermohydrodynamic lubrication (THL) model (model A), based on the isothermal turbulent lubrication model developed in 1971 by Aoki and Harada. The Aoki-Harada theory is characterized by its modified definition of mixing length which enables its velocity profile in the lubricating oil film to agree very well with measurements not only in the log region (full turbulent layer) but also in the viscous sublayer and the buffer layer. On the other hand, Taniguchi et al. derived a three-dimensional turbulent THL model (model B), based on the isothermal turbulent lubrication model developed in 1965 by Ng and Pan, and Mikami et al. derived a two-dimensional turbulent THL model (model C), based on the Aoki-Harada model. The present authors coded and used these three different turbulent THL models to predict the static performance of a four-pad tilting pad journal bearing of a real size and to compare the predictions with measurements. The theoretical results given by model A were found to be in better agreement with measurements obtained in a test rig of the bearing, compared with those given by models B and C.
Design of bearings on the basis of thermohydrodynamic analysis
Authors: Jang J Y , Khonsari M M
Published: October 2004

The steady state thermal behaviour of hydrodynamic bearings can be characterized by two unique dimensionless temperature rise parameters κ1 and κ2. Using these parameters, the results of extensive thermohydrodynamic simulations can be generalized for design purposes. The objective of this paper is to develop appropriate expressions for rapid estimation of the maximum temperature and the effective temperature as well as the bearing performance parameters. A series of examples is provided, illustrating the utility of these expressions for thrust and journal bearing designs.
Relevance of the thermoelastohydrodynamic model in the analysis of a plain journal bearing subjected to severe operating conditions
Authors: Bouyer J , Fillon M
Published: October 2004

Bearings, which were initially designed to support loads, are nowadays being used more and more in machines and most of them are subjected to severe operating conditions as far as temperature or minimum film thickness are concerned. This can be considered as the result of the increases in speed and load, which increase the dissipated power in the lubricant, and also the temperature, thus significantly modifying the lubricant characteristics and bearing performance. This leads, on the one hand, to a decrease in the lubricant viscosity, and therefore the load capacity, and, on the other hand, to mechanical and thermal deformations of the contact surfaces which can, under severe operating conditions, be greater than the minimum film thickness.

The present study investigates the relevance of taking into account the deformations and how they can influence bearing performance prediction. The operating conditions are variable, with the radial load ranging up to 150kN and the rotational speed ranging up to 15000r/min. The thermoelastohydrodynamic (TEHD) model is compared to an existing thermohydrodynamic (THD) model in order to find the point at which it is necessary to take into account deformations in the numerical simulation and thus ensure good prediction of bearing behaviour.

Under severe conditions, the THD model was found not to give good results for bearing performance and geometry; i.e. the hydrodynamic pressure can be dangerously overestimated, the minimum film thickness can be underestimated and the bearing operating radial clearance can be increased by over 10 per cent.
Influence of oil viscosity grade on thrust pad bearing operation
Authors: Glavatskih S B , DeCamillo S
Published: October 2004

The effect of oil viscosity grade on the performance of tilting pad thrust bearings is examined in a wide range of shaft speeds and specific bearing loads. Data being discussed were obtained in tests carried out with 228 mm outer diameter (o.d.) and 267 mm o.d. bearings lubricated with ISO VG32 and ISO VG68 mineral oils in a fully flooded mode. In a low-speed range (below 40 m/s), the performance of the 228 mm bearing is analysed in terms of pad and collar temperatures, power loss and oil film thickness. Pad temperature and power loss are employed in the analyses of the 267 mm o.d. bearing operated at high sliding speeds of up to 115 m/s. The results show that there is a significant effect of oil viscosity grade on bearing main operating parameters. The substitution of ISO VG32 oil for ISO VG68 oil results in considerably reduced pad temperatures, lower power loss and thinner oil film thickness. However, no measurable difference in power loss was observed after the onset of turbulence. The influence of oil viscosity grade on pad temperature pattern is analysed. The thermal effect of oil viscosity grade on pad temperature pattern and power loss is also compared with the effect of offset pivot.
Evaluation of water turbine hydrodynamic thrust bearing performance on the basis of thermoelastohydrodynamic calculations and operational data
Authors: Dąbrowski L , Wasilczuk M
Published: October 2004

An analysis of thrust bearing performance was taken up in order to assess the possibility of bearing installation in a modernized Kaplan turbine. Apart from analysis of the records of machine operation, thermoelastohydrodynamic calculations were carried out. A bearing design incorporating a mechanism of compensation of thermal deformation was of interest, especially as the machine and its bearings were designed earlier than 1952, while the first analyses of such mechanisms known to the authors were published in the 1960s. Apart from direct analysis of the feasibility of the bearing in new operating conditions, the authors carried out a study of the influence of the two most important design parameters on the bearing performance. Thermoelastohydrodynamic calculations showed that the bearing was surprisingly well designed, especially as it was designed without the aid of contemporary calculation methods and techniques. The main conclusion of the analysis was that the bearing pads can be used without any modifications. In addition, it was recommended that the jacking mechanism be redesigned in order to improve load distribution among the pads and facilitate bearing aligning during assembly. The bearing housing was also redesigned in order to reduce the stresses in the welded joints.
Investigation of diesel generator shaft and bearing failures
Authors: Craighead I A , Gray T G F
Published: October 2004

A shaft failure in a 634 kW diesel generator after 4000 hours of operation required investigation, especially when similar sets began to show signs of excessive bearing housing wear. The failure was found to be due to torsional fatigue caused by operation at an unforeseen resonant condition. The damage to the bearing housing of this type of set was also attributed to this behaviour. Replacement of the bearings and housings and redesign of the flexible coupling has been undertaken to prevent further failures. Modifications to design procedures are now being adopted to ensure similar problems do not occur in other existing or new machines.
Combined multi-body dynamics and experimental investigation for determination of the cam-flat tappet contact condition
Authors: Teodorescu M , Taraza D
Published: October 2004

The paper investigates the tribological contact conditions between a polynomial automotive cam and a flat follower. A multi-body model of the system is presented to take into account the complex tappet motions. A set of such models is presented in order to predict the cam-tappet friction force, the tappet-tappet bore friction force and the resulting tappet spin. The tribological conditions giving rise to these kinetic actions include the elastohydrodynamic regime of lubrication in the concentrated cam-follower contact and a mix of hydrodynamic and boundary friction action in the tappet-tappet bore contact. While boundary friction dominates the tappet-tappet bore friction at low engine speeds, for high engine speeds the boundary friction dominates the closing event of the cam, and hydrodynamic and mixed lubrication dominate the opening event of the cam. The simplified friction models are experimentally validated on a single-cylinder diesel engine. The measuring techniques are based on a redesigned engine tappet equipped with four strain gauge bridges.
Modelling and index analysis of a Delta-type mechanism
Authors: Hsu K-S , Karkoub M , Tsai M-C , Her M-G
Published: October 2004

A new type of three-dimensional parallel robot with a human interface as well as parallel motion control of a platform manipulator actuated by three a.c. servomotors is presented in this paper. The performance of this parallel robot is analysed using its forward and inverse kinematics. The analysis is performed using known quantified and graphical performance synthesis tools. Computer simulations of the parallel robot system have shown good correlation between physical interpretations and the results of using the theoretical analysis tools.
Mode acceleration approach for rotating wind turbine blades
Authors: Murtagh P J , Basu B , Broderick B M
Published: October 2004

This paper presents a time-domain analytical approach for evaluating the displacement response in the flapping direction of rotating wind turbine blades subjected to stationary stochastic wind loading. This approach includes the effects of rotational sampling of the wind spectra on the blades. The blades are modelled as discrete multi-degree-of-freedom systems, consisting of tapered beams of rectangular hollow cross-section built using the finite element software code ANSYS. ANSYS is used to obtain the stiffness matrices of the blades, allowing the free vibration characteristics of the rotating blades to be determined by analytical formulation. A geometric stiffness matrix is included in the free vibration solution allowing for the centrifugal stiffening effects experienced by the blades to be included. Once the natural frequencies and mode shapes are obtained, the mode acceleration technique is employed to predict nodal responses to the prescribed wind loading. Nodal wind loading is obtained by generating artificial drag force time-histories, which have elevated energy at frequencies corresponding to integer multiples of the blade rotational frequency, in order to replicate realistic blade loading conditions. Blade nodal displacements based on rotationally sampled and nonrotationally sampled spectra are obtained for varying rotational frequencies. Blade response is also obtained in the frequency domain and used to verify the time-domain results.
Development, Growth and Policy Reform in the Middle East and North Africa since 1950
Authors: Yousef Tarik M
Published: October 2004

The September 11 terrorist attacks ignited global interest in the Middle East. Observers in the region and abroad were quick to highlight the development “deficits” in Middle Eastern countries which have been linked to everything from structural economic imbalances to deficient political systems, the curse of natural resources, and even culture and religion. This paper reviews the development history of the Middle East and North Africa region in the post-World War II era, providing a framework for understanding past outcomes, current challenges and the potential for economic and political reform.
Recommendations for Further Reading
Authors: Saffran Bernard
Published: October 2004

This section will list readings that may be especially useful to teachers of undergraduate economics, as well as other articles that are of broader cultural interest. In general, the articles chosen will be expository or integrative and not focus on original research. If you write or read an appropriate article, please send a copy of the article (and possibly a few sentences describing it) to Bernard Saffran, c/o Journal of Economic Perspectives, Department of Economics, Swarthmore College, Swarthmore, PA 19081.
The Capital Asset Pricing Model
Authors: Perold André F
Published: October 2004

The Capital Asset Pricing Model (CAPM) revolutionized modern finance. Developed in the early 1960s by William Sharpe, Jack Treynor, John Lintner and Jan Mossin, the model provided the first coherent framework for relating the required return on an investment to the risk of that investment. This paper lays out the key ideas of the model, places its development in a historical context, and discusses its applications and enduring importance to the field of finance.
Should We Fear Derivatives?
Authors: Stulz René M
Published: October 2004

This paper discusses the extent to which derivatives pose threats to firms and to the economy. After reviewing the derivatives markets and putting in perspective the various measures of the size of these markets, the paper shows who uses derivatives and why. The difficulties firms face in valuing derivatives portfolios are evaluated. Although academics pay much attention to no-arbitrage pricing results, the paper points out that there can be considerable subjectivity in the pricing of derivatives that do not have highly liquid markets. It is shown that the known risks of derivatives portfolios can generally be measured and managed well at the firm level. However, derivatives can create systemic risks when a market participant becomes excessively large relative to particular derivatives markets. Overall, the benefits of derivatives outweigh the potential threats.
Are We Consuming Too Much?
Authors: Arrow Kenneth , Dasgupta Partha , Goulder Lawrence , Daily Gretchen , Ehrlich Paul , Heal Geoffrey , Levin Simon , Mäler Karl-Göran , Schneider Stephen , Starrett David , Walker Brian
Published: October 2004

This paper articulates and applies frameworks for examining whether consumption is excessive. We consider two criteria for the possible excessiveness (or insufficiency) of current consumption. One is an intertemporal utility-maximization criterion: actual current consumption is deemed excessive if it is higher than the level of current consumption on the consumption path that maximizes the present discounted value of utility. The other is a sustainability criterion, which requires that current consumption be consistent with non-declining living standards over time. We extend previous theoretical approaches by offering a formula for the sustainability criterion that accounts for population growth and technological change. In applying this formula, we find that some poor regions of the world are failing to meet the sustainability criterion: in these regions, genuine wealth per capita is falling as investments in human and manufactured capital are not sufficient to offset the depletion of natural capital.
Women in Economics: Moving Up or Falling Off the Academic Career Ladder?
Authors: Ginther Donna K , Kahn Shulamit
Published: October 2004

The percentage of economics doctorates awarded to women has increased over the past twenty years. This article considers whether women Ph.D. economists have increased their representation in academia, particularly at higher tenured ranks. Our study draws upon several empirical approaches and multiple data sets for the 1990s. We find that when compared with other academic disciplines, women in economics are less likely to get tenure and take longer to achieve it. Although gender differences in productivity and the effect of children on promotion partly explain women's lesser chances of receiving tenure in economics, a significant portion of the gender promotion gap remains unexplained by observable characteristics.
Where Ricardo and Mill Rebut and Confirm Arguments of Mainstream Economists Supporting Globalization
Authors: Samuelson Paul A
Published: October 2004

Autarky real per capita well being, does not deny that new technical Chinese progress in goods that America previously had competitive advantage in can, ceteris paribus, lower permanently measurable per capita U.S. real income. Nor does it deny that technical progress in China's export goods can, ceteris paribus, hurt permanently her own net measurable per capita real income itself when demand inelasticity prevails. Ergo, the winds of dynamic comparative advantage cannot be counted on to create in each region new net gains of the gainers assuredly greater than the new net losses of the losers. However, correct Ricardian theory does imply that worldwide real income per capita does gain net, so that winners' winnings will suffice worldwide to more than compensate losers' losings--some cold comfort in a scenario of many semi-autonomous nations.
Comments
Authors: Kouliavtsev Mikhail S , Werden Gregory J
Published: October 2004

To be considered for publication in the Comments section, letters should be relatively short—generally fewer than 1,000 words—and should be sent to the journal offices at the address appearing inside the front cover. The editors will choose which letters will be published. All published letters will be subject to editing for style and length.
Why the Middle East is Economically Underdeveloped: Historical Mechanisms of Institutional Stagnation
Authors: Kuran Timur
Published: October 2004

Although a millennium ago the Middle East was not an economic laggard, by the 18th century it exhibited clear signs of economic backwardness. The reason for this transformation is that certain components of the region's legal infrastructure stagnated as their Western counterparts gave way to the modern economy. Among the institutions that generated evolutionary bottlenecks are the Islamic law of inheritance, which inhibited capital accumulation; the absence in Islamic law of the concept of a corporation and the consequent weaknesses of civil society; and the waqf, which locked vast resources into unproductive organizations for the delivery of social services. All of these obstacles to economic development were largely overcome through radical reforms initiated in the nineteenth century. Nevertheless, traditional Islamic law remains a factor in the Middle East's ongoing economic disappointments. The weakness of the region's private economic sectors and its human capital deficiency stand among the lasting consequences of traditional Islamic law.
The Capital Asset Pricing Model: Theory and Evidence
Authors: Fama Eugene F , French Kenneth R
Published: October 2004

The capital asset pricing model (CAPM) of William Sharpe (1964) and John Lintner (1965) marks the birth of asset pricing theory (resulting in a Nobel Prize for Sharpe in 1990). Before their breakthrough, there were no asset pricing models built from first principles about the nature of tastes and investment opportunities and with clear testable predictions about risk and return. Four decades later, the CAPM is still widely used in applications, such as estimating the cost of equity capital for firms and evaluating the performance of managed portfolios. And it is the centerpiece, indeed often the only asset pricing model taught in MBA level investment courses.

The attraction of the CAPM is its powerfully simple logic and intuitively pleasing predictions about how to measure risk and about the relation between expected return and risk. Unfortunately, perhaps because of its simplicity, the empirical record of the model is poor - poor enough to invalidate the way it is used in applications. The model's empirical problems may reflect true failings. (It is, after all, just a model.) But they may also be due to shortcomings of the empirical tests, most notably, poor proxies for the market portfolio of invested wealth, which plays a central role in the model's predictions. We argue, however, that if the market proxy problem invalidates tests of the model, it also invalidates most applications, which typically borrow the market proxies used in empirical tests. For perspective on the CAPM's predictions about risk and expected return, we begin with a brief summary of its logic. We then review the history of empirical work on the model and what it says about shortcomings of the CAPM that pose challenges to be explained by more complicated models.
Of bikers, teachers and Germans: Groups' diverging views about their prototypicality
Authors: Waldzus Sven , Mummendey Amélie , Wenzel Michael , Boettcher Franziska
Published: October 2004

The in‐group projection model hypothesizes that members of social groups generalize attributes of their in‐group to a superordinate category that provides dimensions for comparisons between in‐group and out‐group (in‐group projection). As a result, both groups in an intergroup situation should disagree about their relative prototypicality for the superordinate category. Three studies confirmed this prediction. In Study 1 (N = 54), it was found that different groups of motor bikers (chopper‐bikers vs. sport‐bikers) perceived their own subgroup to be the more typical biker group than the respective out‐group. Study 2 (N = 60) showed the same divergence of perspectives in the context of more formal subgroups of teachers (primary‐school teachers vs. high‐school teachers). In a third study (N = 157), the relative character of in‐group projection was demonstrated in an intergroup context with strong reality constraints due to differences in group size, status and power. Although there was consensus between both groups that the majority (West Germans) was more prototypical of the superordinate group (Germans) than the minority (East Germans), majority members perceived the groups' difference in prototypicality to be greater than minority members did.
Tri‐generational family conversations: Communication accommodation and brokering
Authors: Ng Sik Hung , He Anping , Loong Cynthia
Published: October 2004

Communication between grandparents and grandchildren can be superficial because of insufficient common ground between them. Among Chinese immigrant families in New Zealand, communication is complicated by linguistic mismatches, as grandparents may be proficient only in Chinese and grandchildren in English. To surmount these communication barriers, middle‐aged parents (who know the cultures and languages of both grandparents and grandchildren) may play the role of a ‘communication broker’ to encourage and assist the two generations to conversationally move towards each other. We identified 35 cases (tokens) of brokering in 12 New Zealand Chinese families and found, as hypothesized, that brokering was significantly overrepresented in moderately (compared to high‐ or low‐) acculturated families, and that brokers were mostly middle‐aged parents. In the qualitative part of the study, detailed turn‐by‐turn analyses of brokering were conducted to reveal how brokering was occasioned, its subsequent enactment and eventual outcome. The results extend the understanding of unmediated communication accommodation in dyadic settings to mediated accommodation in group settings wherein a third (and sometimes a fourth) person brokers the accommodation. The resultant framework of brokered accommodation will be useful for research on other group conversations such as those involving a nurse brokering between a doctor and a patient.
False consensus in social context: Differential projection and perceived social distance
Authors: Jones Paul E.
Published: October 2004

The study implicates the notion of perceived social distance as an explanation of why ingroup false consensus exceeds outgroup false consensus. Whilst previous demonstrations are best understood from social identity perspectives, the findings reported here suggest that self‐group as well as inter‐group comparisons can underlie such effects. In particular, perceived social distance was shown to mediate the effect of social categorisation: ingroup false consensus was greater because more social distance was perceived with the outgroup. The findings also extended to non‐student samples and generalised across both opinion and ability items. In addition, examining the effect of item type in conjunction with social categorisation seriously challenged the generality of the false consensus effect.
Death and football: An analysis of men's talk about emotions
Authors: Walton Chris , Coyle Adrian , Lyons Evanthia
Published: October 2004

This study is concerned with men's talk about emotions and with how emotion discourses function in the construction and negotiation of masculine ways of doing emotions and of consonant masculine subject positions. A sample group of 16 men, who were recruited from two social contexts in England, participated in focus groups on ‘men and emotions’. Group discussions were transcribed and analysed using discourse analysis. Participants drew upon a range of discursive resources in constructing masculine emotional behaviour and negotiating masculine subject positions. They constructed men as emotional beings, but only within specific, rule‐governed contexts, and cited death, a football match and a nightclub scenario as prototypical contexts for the permissible/understandable expression of grief, joy and anger, respectively. However, in the nightclub scenario, the men distanced themselves from the expression of anger as violence, whilst maintaining a masculine subject position. These discursive practices are discussed in terms of the possibilities for effecting change in men's emotional lives.
Gene Expression Analysis in Platelets from a Single Donor: Evaluation of a PCR-Based Amplification Technique
Authors: Rox Jutta Maria , Bugert Peter , Müller Jens , Schorr Alexander , Hanfland Peter , Madlener Katharina , Klüter Harald , Pötzsch Bernd
Published: October 2004

Background: Genetic analysis of platelet mRNA may facilitate the diagnosis of disorders affecting the megakaryocytic-platelet lineage. Its use, however, is limited by the exceptionally small yield of platelet mRNA and the risk of leukocyte contamination during platelet preparation.

Methods: We depleted platelet suspensions of leukocytes by filtration and used a PCR-based RNA amplification step [switching mechanism at the 5′ end of RNA templates (SMART)]. We tested the reliability and precision of the RNA amplification procedure by use of real-time PCR to measure quantities of specific transcripts: von Willebrand factor (vWF), A-subunit of coagulation factor XIII (F13A), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Microarray analysis was performed on platelet RNA with and without amplification.

Results: Microgram quantities of platelet-specific cDNAs were produced from as little as 50 ng of total platelet RNA or 40 mL of whole blood. At cycle numbers <16, amplification of all transcripts tested was exponential with slightly more efficient amplification of low-abundance transcripts. Expression profiling of 9850 genes gave identical results for 9815 genes (1576 positive/8239 negative). Eight transcripts failed to be amplified by the SMART procedure. Expression of vWF, F13A, and GAPDH transcripts showed only minor day-to-day variations in three healthy individuals.

Conclusion: The proposed protocol makes extremely small amounts of platelet RNA available for gene expression analysis in single patients.
The Biochemistry of Gene Therapy for AIDS
Authors: Savarino Andrea , Piero Pescarmona Gian , Turco Emilia , Gupta Phalguni
Published: October 2004

Gene therapy has enormous potential and could in the near future involve the clinical biochemist in monitoring its efficacy. The involvement of clinical biochemists in this field could be not only in evaluating the impact of a gene-based strategy on disease progression, but also in measuring the expression of the products of therapeutic genes in treated individuals. Indeed, gene therapy presents new possibilities for the treatment of many diseases and, in particular, merits consideration in the treatment of a fatal disease like AIDS. The aim of this paper is to review the biochemical basis and clinical relevance of the gene therapy approaches directed towards the inhibition of human immunodeficiency virus type-1. We discuss the goals which have been achieved, the problems which have occurred and the efforts that are being made to solve them. In this regard, particular attention is paid to new strategies targeting ‘therapeutic’ enzymes to human immunodeficiency virus type-1 nucleic acids.
Reticulocytes and Reticulated Platelets: Simultaneous Measurement in Whole Blood by Flow Cytometry
Authors: Rapi Stefano , Ermini Angela , Bartolini Laura , Caldini Anna , Del Genovese Alessandra , Miele Anna Rosa , Buggiani Antonio , Fanelli Alessandra
Published: October 2004

Reticulated platelets are a fraction of newly released circulating elements characterized by a residual amount of RNA. It has been suggested that the reticulated platelet count, providing an estimate of thrombopoiesis in the same way as erythrocyte reticulocyte count is a measure of erythropoiesis, may be useful in the study of thrombocytopenic disorders. Reticulated red cells and platelets can be analyzed by flow cytometry using specific stains for nucleic acids such as Thiazole Orange and Auramine-O. The aim of our work was to perform the simultaneous evaluation of reticulated elements in whole blood using a standard flow cytometer and to correlate the results obtained with a dedicated cytometer. A group of 14 patients with abnormal absolute reticulocyte counts (range 1.1–11%) and a group of 41 patients showing a platelet discrimination error when analyzed with a dedicated flow cytometer (Sysmex R1000) were enrolled. Linear amplification of both scatter and fluorescence was used to perform reticulocyte count. A gate was set on platelet dimensions, and logarithmic amplification of scatter and fluorescence was used to count reticulated platelets. A good correlation was obtained both for results of reticulocyte count (r2 = 0.9825) and for reticulated platelets (r2 = 0.8717) between our method and those using dedicated instruments. These data show that reticulated platelet count may be easily introduced in clinical laboratories that routinely perform reticulocyte count by flow cytometry.
Salivary Cortisol - an Alternative to Serum Cortisol Determinations in Dynamic Function Tests
Authors: Aardal-Eriksson Elisabeth , Karlberg Bengt E. , Holm Ann-Charlotte
Published: October 2004

Salivary cortisol was measured as an alternative to serum cortisol as a marker for adrenocortical function following insulin tolerance test, corticotropin-releasing-hormone stimulation and adreno-corticotrophic hormone stimulation. During insulin tolerance test and corticotropin-releasing-hormone stimulation adreno-corticotrophic hormone was also measured. The tests were performed on healthy control subjects as well as on patients under investigation for various disturbances in the hypothalamic-pituitary-adrenocortical axis (insulin tolerance test: 3 controls on two occasions and 14 patients; corticotropin-releasing-hormone stimulation: 4 controls and 18 patients; adreno-corticotrophic hormone stimulation: 6 controls and 10 patients). Five patients underwent both insulin tolerance test and corticotropin-releasing-hormone stimulation. Using criteria for adequate cortisol response in serum, the patients were classified as good or poor responders. In 42 of the 45 tests performed the same conclusion as to cortisol status was drawn when based on serum and salivary cortisol responses. In healthy subjects and good responders the mean cortisol relative increase was greater in saliva than in serum in all three tests (p < 0.05). Characteristic of the results for the insulin tolerance test was a significant initial mean decrease (p < 0.05), not found in serum, and the highest observed salivary cortisol value was delayed for at least 30 minutes compared to that in serum. Plasma adreno-corticotrophic hormone correlated significantly with the cortisol concentrations determined 15 minutes later in serum (r = 0.54–0.64) and in saliva (r = 0.76–0.85). The more pronounced cortisol response in saliva than in serum and its closer correlation with adreno-corticotrophic hormone offer advantages over serum cortisol, suggesting salivary cortisol measurement may be used as an alternative parameter in dynamic endocrine tets.
A Time-Resolved Fluorescence Immunoassay for the Measurement of Testosterone in Saliva: Monitoring of Testosterone Replacement Therapy with Testosterone Buciclate
Authors: Tschöp Matthias , Behre Hermann M. , Nieschlag Eberhard , Dressendörfer Regina A. , Strasburger Christian J.
Published: October 2004

Monitoring of testosterone replacement therapy requires a reliable method for testosterone measurement. Determination of salivary testosterone, which reflects the hormone's biologically active plasma fraction, is a superior technique for this purpose. The aim of the present study was to establish a new sensitive time-resolved fluorescence immunoassay for the accurate measurement of testosterone levels in saliva and to validate it by monitoring testosterone replacement therapy in eight hypogonadal men.

A clinical phase I-study with the new ester testosterone buciclate was performed to search for new testosterone preparations to produce constant serum levels in the therapy of male hypogonadism. After two control examinations eight male patients with primary hypogonadism were randomly assigned to two treatment groups (n= 2×4) and given single doses of either 200 mg (group I) or 600 mg (group II) testosterone buciclate intramuscularly. Saliva and blood samples were obtained 1, 2, 3, 5 and 7 days post injection and then weekly for three months.

The time-resolved fluorescence immunoassay for salivary testosterone shows a detection limit of 16 pmol/l, an intra-assay CV of 8.9 % (at a testosterone concentration of 302 pmol/l), an inter-assay CV of 8.7 % (at a testosterone concentration of 305 pmol/l) and a good correlation with an established radioimmunsassay of r=0.89. The sample volume required by this method is only 180 μl for extraction and duplicate determination. The assay procedure requires no more than three hours.

In group I (200 mg) testosterone did not increase to normal levels either in saliva or in serum. However, in group II, androgen levels increased significantly and were maintained in the normal range for up to 12 weeks with maximal salivary testosterone levels of 303 ±18 pmol/l (mean ±SE) and maximal testosterone levels of 13.1 ±0.9 nmol/l (mean±SE) in serum in study week 6 and 7.

The time-resolved fluorescence immunoassay for salivary testosterone provides a useful tool for monitoring androgen status in men and women and is well suited for the follow-up of testosterone replacement therapy on an outpatient basis. The long-acting ester testosterone buciclate is a promising agent for substitution therapy of male hypogonadism and in combination with testosterone monitoring in saliva offers an interesting new perspective for male contraception.
Neuron-Specific Enolase: Reference Values in Cord Blood
Authors: Kintzel Kathrin , Sonntag Josef , Strauß Evelyn , Obladen Michael
Published: October 2004

With foetal sonography prenatal detection of tumours has become more frequent. To evaluate and treat these infants it is necessary to identify the tumour postnatally. Elevated neuron-specific enolase is a biochemical marker of neuroblastoma. Since conditions during birth may influence neuron-specific enolase concentration in foetal serum, specific reference values in cord blood are required. Cord blood samples were taken from 192 healthy term newborns and concentration of neuron-specific enolase was measured by enzyme immunoassay (EIA). Median neuron-specific enolase concentration in the reference group was 8.0 μg/l and the 5th–95th percentiles were 4.8–19.4 μg/l. No differences between male and female newborns were detected (p = 0.13).

Measurement of neuron-specific enoloase in cord blood, in comparison with our reference values, offers an early postnatal possibility of confirming the diagnosis of neuroblastoma.
Developments in Quantitative PCR
Authors: Orlando Claudio , Pinzani Pamela , Pazzagli Mario
Published: October 2004

In recent years the growing interest in quantitative applications of the polymerase chain reaction (PCR) has favoured the development of a large number of assay procedures suitable for this purpose. In this paper we review some basic principles of quantitative PCR and in particular the role of reference materials and calibrators and the different strategies adopted for nucleic acid quantification. We focus on two methodological approaches for quantitative PCR in this review: competitive PCR and real-time quantitative PCR based on the use of fluorogenic probes. The first is one of the most common methods of quantitative PCR and we discuss the structure of the competitors and the various assay procedures. The second section is dedicated to a recent promising technology for quantitative PCR in which the use of fluorogenic probes and dedicated instrumentation allows the development of homogeneous methods. Assay performance of these methods in terms of practicability and reliability indicates that these kinds of technologies will have a widespread use in the clinical laboratory in the near future.
Endemic Nephropathy in Croatia
Authors: Čvorišćec Dubravka , Čeović Stjepan , Boršo Gordana , Rukavina Ana Stavljenić
Published: October 2004

Endemic nephropathy is a chronic renal disease with a high prevalence in a geographically limited area of Croatia. It has also been recorded in some parts of Bosnia, Serbia, Bulgaria and Romania. Despite numerous studies conducted to date, the etiology of this disease has not been clarified. Pathological studies of the kidney in the early stage of endemic nephropathy have shown renal tubules to be the primary sites of the pathologic process with an interstitial tissue reaction, whereas glomerular alterations are of a secondary character. Tubulointerstitial lesions can thus account for the symptoms of the disease, i.e. tubular proteinuria and reduced urine concentration capacity and urine acidification. Also, an increased incidence of malignant tumours of the urinary tract was found in the same geographic area.
Recombinant Human Heart-Type Fatty Acid-Binding Protein as Standard in Immunochemical Assays
Authors: Schreiber Andrea , Specht Bernfried , Pelsers Maurice M. A. L. , Glatz Jan F. C. , Börchers Torsten , Spener Friedrich
Published: October 2004

Cytoplasmic heart-type fatty acid-binding protein has recently gained much attention in clinical diagnosis as a very early marker of acute myocardial infarction. Immunoassays have been developed for determination of this protein in plasma and urine samples. In the present study it is shown that those types of fatty acid-binding proteins which are abundant in tissues other than heart and muscle do not interfere with immunochemical determination of heart-type fatty acid-binding protein. To provide sufficient protein of consistent quality as standard in these immunoassays, human heart-type fatty acid-binding protein was cloned, expressd in Escherichia coli and purified to homogeneity. For quantitation of the recombinant protein its extinction coefficient was determined. Comparison of the recombinant and tissue-derived proteins by a variety of methods revealed both proteins to show similar kinetic as well as equilibrium constants with respect to two monoclonal antibodies currently applied in immunochemical detection of heart-type fatty acid-binding protein. Both preparations were indistiguishable in sandwich-ELISA and immunosensor measurements. A high stability of the recombinant protein was proven by ELISA measurements during storage and several freeze and thaw cycles. Thus, recombinant and tissue-derived heart-type fatty acid-binding proteins are immunochemically equivalent. The recombinant human heart-type fatty acid-binding protein is now available as standard for immunoassays.
Sialic Acid, Transketolase and Na+, K+, ATPase in Patients with Rheumatoid Arthritis
Authors: Kızıltunç Ahmet , Çoǧalgil Şirzat , Uǧur Mahir , Avcı Bahattin , Akçay Fatih
Published: October 2004

We studied transketolase activity of red blood cell hemolysates, and Na+, K+, ATPase activity and sialic acid concentration in red blood cell membranes from 52 patients with rheumatoid arthritis and 24 control subjects. Decreased red blood cell membrane Na+, K+, ATPase activity and sialic acid concentration and decreased transketolase in red blood cell hemolysates were observed in rheumatoid arthritis patients compared with control subjects (p < 0.001). Erythrocyte sedimentation rate and C-reactive protein values were increased in rheumatoid arthritis patients compared with control subjects (p < 0.0001). Significant correlations between sialic acid and Na+, K+, ATPase (r = 0.65, p < 0.001) and between sialic acid and transketolase (r = 0.58, p < 0.001) were observed. Erythrocyte sedimentation rate and C-reactive protein levels did not correlate with Na+, K+, ATPase activity or with sialic acid or transketolase in rheumatoid arthritis patients.

These data show that decreases in Na+, K+, ATPase, and transketolase activities and sialic acid concentration are present in rheumatoid arthritis patients, and that the decrease in Na+, K+, ATPase and transketolase activities in rheumatoid arthritis might be due to decreased sialic acid.
Quantitation and Enzymatic Activity of the Alkaline Protease from Pseudomonas aeruginosa in Culture Supernatants from Clinical Strains
Authors: Louis Dominique , Sorlier Pierre , Wallach Jean
Published: October 2004

Alkaline protease from Pseudomonas aeruginosa (E.C. 3.4.24.40), also called pseudomonal serralysin, plays an important role in the infection bacterial process. The alkaline protease concentration and activity in the culture supernatants of 23 Pseudomonas aeruginosa strains from patients suffering from cystic fibrosis were determined by using an ELISA procedure and a specific enzymatic activity test. No correlation was demonstrated between the activity and the concentration of alkaline protease. This could be explained by the presence of an inactive precursor and a partial hydrolysis of the enzyme, confirmed by SDS-PAGE and Western blotting in the supernatants. The activity test is the only one allowing a quantification of the presence of an active form of alkaline protease.