bluuebunny/crossref_metadata_2025 huggingface dataset:
Overachievement im Lesen und Rechtschreiben:
Authors: Metz Ulrike , Marx Peter , Weber Jutta , Schneider Wolfgang
Published: June 2003

Zusammenfassung. Die vorliegende Studie beschäftigt sich mit der Legitimation der Diskrepanzdefinition der Legasthenie. Es wurde überprüft, inwieweit spezifische Ursachenmuster auf die Gruppe der intelligenten lese-rechtschreibschwachen Kinder, die eine Diskrepanz zwischen Intelligenz und Lese-Rechtschreibleistung aufweisen, beschränkt sind. Dazu wurden Overachiever im Bereich des Lesens und Rechtschreibens am Ende der 3. Jahrgangsstufe mit gleichaltrigen Legasthenikern, allgemein lese-rechtschreibschwachen Kindern mit niedriger Intelligenz und einer Kontrollgruppe hinsichtlich ihrer phonologischen und visuellen Informationsverarbeitung sowie der Art ihrer Rechtschreibfehler verglichen. Overachiever wurden hierbei definiert als Kinder, die im Vergleich zu ihrer unterdurchschnittlichen Intelligenz erwartungswidrig gute Leistungen im Lesen und Rechtschreiben erbringen. Die Hinzunahme dieser intelligenzparallelisierten Kontrollgruppe für die allgemein lese-rechtschreibschwachen Kinder vervollständigte das Design zu einem kompletten Vierfelderschema (Intelligenz Lese-Rechtschreibkompetenz), worauf bisherige Studien verzichteten. Sowohl Kontrollkinder als auch Overachiever verfügten gegenüber Legasthenikern bzw. allgemein lese-rechtschreibschwachen Kindern über eine deutlich bessere phonologische Informationsverarbeitung und wiesen einen geringeren Anteil an Wahrnehmungsfehlern im Rechtschreibtest auf. Für beide lese-rechtschreibschwachen Gruppen zeigten sich keinerlei Defizite hinsichtlich der visuellen Informationsverarbeitung. Die Ergebnisse liefern ein empirisches Argument gegen die Annahme, dass bei intelligenten lese-rechtschreibschwachen Kindern ein qualitativ anderes Ursachenmuster als bei unterdurchschnittlich intelligenten lese-rechtschreibschwachen Kindern vorliegt und damit nur bei ersteren von einer spezifischen Störung (Legasthenie) auszugehen ist.
Das physische Selbstkonzept bei sportlich aktiven Jugendlichen in Abhängigkeit von sportlicher Leistungsentwicklung und Geschlecht
Authors: Alfermann Dorothee , Stiller Jeannine , Würth Sabine
Published: June 2003

Zusammenfassung. Vor dem Hintergrund eines multidimensionalen Modells des physischen Selbstkonzepts soll die vorliegende Studie prüfen, wie jugendliche Athletinnen und Athleten ihre körperlichen Fähigkeiten und physische Attraktivität wahrnehmen, und ob diese Wahrnehmung zeitlichen Veränderungen unterliegt. Zur Überprüfung der Fragestellung wurden 191 sportlich aktive Jugendliche im Alter von 8 bis 20 Jahren (109 Mädchen und 82 Jungen) schriftlich befragt. Eine Follow-up-Erhebung erfolgte ein Jahr später. Als Messinstrumente dienten standardisierte Skalen zur Erfassung physischer Fähigkeiten und physischer Attraktivität. Die Ergebnisse zeigen, dass Jungen ein positiveres physisches Selbstkonzept aufweisen als Mädchen. Querschnittlich zeigt sich kein Zusammenhang mit dem sportlichen Leistungsniveau. Die Follow-up-Erhebung weist demgegenüber darauf hin, dass ein Anstieg des sportlichen Leistungsniveaus mit Verbesserungen im Selbstkonzept einhergeht, allerdings nur in Teilbereichen. Andere Bereiche bleiben davon unbeeinflusst. Reifungsbedingte körperliche Veränderungen in der Jugendphase scheinen sich in der untersuchten Gruppe sportlich aktiver Jugendlicher nicht so gravierend auf die Wahrnehmung des eigenen Körpers auszuwirken, wie sie für das Jugendalter bisher berichtet wurden.
Naive Biologie im kindlichen Denken:
Authors: Mähler Claudia , Ahrens Susann
Published: June 2003

Zusammenfassung. In der kognitiven Entwicklungspsychologie wird bereits seit einigen Jahren die Entwicklung bereichsspezifischen Wissens innerhalb fundamentaler Rahmentheorien, v.a. in den Wissensbereichen naive Physik, Biologie und Psychologie untersucht. Von besonderer Bedeutung ist dabei die Frage, ob Kinder kausale Mechanismen verschiedener Domänen (z.B. intentionale vs. mechanische Verursachung) auseinanderhalten können. In der vorliegenden Arbeit ging es um die Differenzierung zwischen naiver Biologie und Soziologie. Gelingt diese Differenzierung, sollten Kinder zwischen Beziehungen, die biologisch bedingt sind (Verwandtschaftsbeziehungen) und solchen, die sozial bedingt sind (Freundschafts- oder Nachbarschaftsbeziehungen), unterscheiden können. Je 25 vier- und sechsjährige Kindergartenkinder wurden in zwei Teilstudien mit kleinen Aufgaben konfrontiert, bei denen sie zwischen Personen ihres erfahrbaren Umfeldes (Eltern, Geschwister, Großeltern, Freunde, Kindergärtnerin, Kinderarzt) anhand des Beziehungstyps differenzieren sollten. Wissen Vorschulkinder, dass Verwandtschaftsbeziehungen auf bestimmte Personen begrenzt sind, Bekanntschaftsbeziehungen hingegen nicht (Teilstudie 1)? Unterscheiden sie zwischen Geschwistern und Freunden bezüglich eines möglichen Anfangs und Endes einer Beziehung (Teilstudie 2)? Für die hier gewählten Indikatoren zeigten sich deutliche Entwicklungsfortschritte im Altersbereich zwischen vier und sechs Jahren. Während die jüngeren Kinder noch keine deutliche Differenzierungsleistung zwischen Verwandtschafts- und Bekanntschaftsbeziehungen zeigen, scheinen die älteren sechsjährigen Kinder für die Besonderheit von Familienbeziehungen sensibilisiert zu sein. Die Ergebnisse weisen darauf hin, dass erst gegen Ende des Vorschulalters ein Verständnis spezifisch biologischer Kausalität im Sinne einer domänspezifischen Theorie erworben wird.
Väterliche Selbstwirksamkeit als Moderator des Zusammenhangs zwischen ökonomischen Härten und depressiver Gestimmtheit bei Jugendlichen
Authors: Forkel Ines , Silbereisen Rainer K.
Published: June 2003

Zusammenfassung. Anliegen der vorliegenden Arbeit war, zu untersuchen, ob hohe generalisierte Selbstwirksamkeit des Vaters weniger ausgeprägten negativen Folgen ökonomischer Härten für den Vater selbst, für die familiären Beziehungen und für die jugendlichen Kinder entspricht. Ausgangspunkt hierfür war ein Familien-Stress-Modell, welches niedriges Pro-Kopf-Einkommen, instabile Arbeitssituation von Mutter und Vater sowie negative Einkommensveränderungen indirekt mit der depressiven Gestimmtheit Jugendlicher verbindet, und zwar einerseits vermittelt über die Wahrnehmung einer wirtschaftlichen Belastung, andererseits über die damit zusammenhängende depressive Gestimmtheit beider Eltern und ein beeinträchtigtes Familienklima. Die Moderatorrolle der väterlichen Selbstwirksamkeit wurde anhand einer Stichprobe von 305 vollständigen Familien mit Jugendlichen im Alter von 10 bis 13 Jahren überprüft. Die Ergebnisse wiesen auf eine protektive Rolle der generalisierten Selbstwirksamkeit des Vaters hin. Die Zusammenhänge zwischen der instabilen Arbeitssituation des Vaters und dessen depressiver Gestimmtheit sowie zwischen väterlicher depressiver Gestimmtheit und der des Jugendlichen fielen bei hoher Selbstwirksamkeit des Vaters geringer aus.
Teilnahmewahrscheinlichkeit und Stichprobenselektivität in altersvergleichenden Erhebungen
Authors: Lüdtke Oliver , Tomasik Martin J. , Lang Frieder R.
Published: June 2003

Zusammenfassung. Die Gültigkeit altersvergleichender Querschnittanalysen in der Entwicklungspsychologie kann nicht nur durch eine Konfundierung von Alters- und Kohortenunterschieden, sondern auch durch selektive und altersspezifische Teilnahmewahrscheinlichkeiten eingeschränkt sein. Von 1531 nach einem Zufallsverfahren aus dem Einwohnermelderegister gezogenen und anschließend kontaktierten jungen, mittelalten und alten Erwachsenen nahmen 1022 Personen (66.8%) an einem kurzen Telefoninterview und davon wiederum 480 (31.4 %) Personen an einer intensiven zwei- bis dreistündigen psychologischen Befragung teil. Eine logistische Regressionsanalyse ergab, dass die Teilnahmewahrscheinlichkeit um so größer war, je jünger, gebildeter, beruflich besser gestellt und zufriedener die Personen waren. Bei alten Erwachsenen, die am Telefoninterview teilnahmen, zeigte sich ein höherer Einfluss der generellen Zufriedenheit auf die Teilnahmebereitschaft als bei jungen Erwachsenen. Auf der Grundlage des Maximum-Likelihood-Verfahrens wurde gezeigt, dass Selektivitätseffekte auf einen höheren Stichprobenausfall bei alten Erwachsenen zurückführbar sind. Es wird diskutiert, inwiefern altersdifferentielle Stichprobenselektivität zu einer Unterschätzung möglicher Altersunterschiede führen kann.
Spatial decay of energy density of tidal internal waves
Authors: Lozovatsky Iossif D. , Morozov Eugene G. , Fernando H. J. S.
Published: June 2003

The spatial decay of energy density of tidal internal waves (TIW) was studied using field data taken in the Indian Ocean near the Mascarene Ridge and in the Canary Basin of the eastern Atlantic near the Heyres‐Irving‐Cruiser chain of seamounts. Several moorings were deployed at distances between 90 and 1745 km east of these topographic features, with instruments located in the depth range 500–2500 m. The energy densities of TIW averaged over the spring‐neap cycle were calculated using semidiurnal tidal components of current and temperature time series as well as local vertical gradients of temperature and density. It was found that the horizontal component of TIW, EH, is less depth‐dependent compared to the vertical component, Eζ, although both components showed a general decrease of magnitude with the distance from topography. The decrease of total energy density ETW = EH + Eζ with distance from the topography is more rapid than that assumed in the work of Morozov [1995], and followed an inverse power law. At a distance of about x ≈ 10λ from the topography (where λ is the wavelength of the first mode), ETW in the main thermocline becomes equal to the energy density of the forcing barotropic tide, whereas for x/λ < 2, ETW exceeds the energy of the entire range of internal waves of the Garrett‐Munk spectrum. A nonhydrostatic, nonlinear, two‐dimensional numerical model shows a reasonable agreement with the observations for x/λ < 2–3, but in the far field it predicts a faster spatial decay of ETW than observed, possibly because of topographic generation of TIW along the measurement swath. The turbulent diffusivity estimates based on the McComas and Muller [1981] model exceeded 10−4 m2/s within the main pycnocline at x = 100 km and suggest mixing enhancements due to TIW up to distances of 1000 km from the topography.
Are there relict crustal fragments beneath the Moho?
Authors: Cook Frederick A. , Vasudevan Kris
Published: June 2003

The application of new data enhancement techniques on a Lithoprobe seismic reflection profile in northwest Canada has produced images of upper mantle structures that are overlain with angular discordance by the reflection Moho and are underlain by a relict Mesoproterozoic subduction zone. The reflection Moho is interpreted to postdate the underlying fabric and may thus have been superimposed on it by thermal and/or structural processes. Reflections within the mantle that are subparallel to the east dipping subduction zone are interpreted as structural fabric that formed during, and perhaps as a consequence of, subduction. Interpretation of the lithology in the upper mantle layering is uncertain, as peridotites, eclogites, mafic granulites, and/or pelitic restites can have velocities and densities appropriate for seismic mantle (or a portion of it). Nevertheless, if some layers beneath the Moho were originally in the crust, they may retain a structural memory.
Exchange processes and nitrogen cycling on the shelf and continental slope of the Black Sea basin
Authors: Grégoire Marilaure , Lacroix Genevieve
Published: June 2003

A 3D coupled biogeochemical‐hydrodynamical model has been applied to the Black Sea to simulate nitrogen cycling and to estimate the exchange of biogeochemical components at the shelf break and between the continental slope and the deep sea. It was found that biological processes on the northwestern shelf are in approximate balance. Primary production is fueled by river discharge, nitrate input from the open sea at the shelf break, and in situ remineralization. The input of nitrate from the open sea is roughly equivalent to the river nitrate discharge but is half the nitrate export from the shelf toward the open sea. Also, the Black Sea shelf acts throughout the year as a nitrate source for the open sea. The amount of shelf production not remineralized in the euphotic layer is 22.2% and is exported to lower layers (20%) or offshore (2.2%). We estimate that the export of carbon from the shelf to the interior of the basin represents 2.5% of the new production of the open sea. The upper slope adjoining the northwestern shelf is the site of downwelling events responsible for the downward transport to the intermediate layer of the continental slope of biogeochemical components exported from the shelf in the upper layer. The shelf has been found to be an efficient trap for the refractory material discharged by the Danube.
Long‐term observation of in situ seismic velocity and attenuation
Authors: Yamamura Keiko , Sano Osam , Utada Hisashi , Takei Yasuko , Nakao Shigeru , Fukao Yoshio
Published: June 2003

We conducted 1‐year continuous measurements of in situ compressional wave velocity and attenuation across a distance of 12 m in a vault at the coast of Miura Bay, Japan, using a piezoelectric transducer as the ultrasonic wave source. We detected, for the first time, periodic variations in both velocity and attenuation, with amplitudes of 0.3%, and of 4%, respectively, corresponding to the diurnal and semidiurnal lunar and solar tides. These variations correlate well with the in situ areal strain change due to tidal ocean loading estimated from the strain records about 100 m away from the observational site. Relative minimum velocity and relative maximum attenuation occur at every time of relative maximum areal strain (expansion), suggesting that opening/closure of pores or cracks of in situ rocks is responsible for these periodic variations. The velocity variation shows a remarkable 14‐day periodicity corresponding to the spring and neap tides, arising from a nonlinear response of the velocity change to tidal strain change such that the velocity change depends on how slowly the tidal dilatation departs from its peak value.
When and where the aftershock activity was depressed: Contrasting decay patterns of the proximate large earthquakes in southern California
Authors: Ogata Yosihiko , Jones Lucile M. , Toda Shinji
Published: June 2003

Seismic quiescence has attracted attention as a possible precursor to a large earthquake. However, sensitive detection of quiescence requires accurate modeling of normal aftershock activity. We apply the epidemic‐type aftershock sequence (ETAS) model that is a natural extension of the modified Omori formula for aftershock decay, allowing further clusters (secondary aftershocks) within an aftershock sequence. The Hector Mine aftershock activity has been normal, relative to the decay predicted by the ETAS model during the 14 months of available data. In contrast, although the aftershock sequence of the 1992 Landers earthquake (M = 7.3), including the 1992 Big Bear earthquake (M = 6.4) and its aftershocks, fits very well to the ETAS up until about 6 months after the main shock, the activity showed clear lowering relative to the modeled rate (relative quiescence) and lasted nearly 7 years, leading up to the Hector Mine earthquake (M = 7.1) in 1999. Specifically, the relative quiescence occurred only in the shallow aftershock activity, down to depths of 5–6 km. The sequence of deeper events showed clear, normal aftershock activity well fitted to the ETAS throughout the whole period. We argue several physical explanations for these results. Among them, we strongly suspect aseismic slips within the Hector Mine rupture source that could inhibit the crustal relaxation process within “shadow zones” of the Coulomb's failure stress change. Furthermore, the aftershock activity of the 1992 Joshua Tree earthquake (M = 6.1) sharply lowered in the same day of the main shock, which can be explained by a similar scenario.
Global soil moisture retrieval from a synthetic L‐band brightness temperature data set
Authors: Pellarin Thierry , Wigneron Jean‐Pierre , Calvet Jean‐Christophe , Waldteufel Philippe
Published: June 2003

A technique to retrieve surface soil moisture was assessed at the global scale using a synthetic data set of L‐band (1.4 GHz) brightness temperatures TB for 2 years, 1987 and 1988. The global TB database consists of half‐degree continental pixels and accounts for within‐pixel heterogeneity, on the basis of 1 km resolution land cover maps. The retrievals were performed using a three‐parameter inversion method applied to the L‐band Microwave Emission of Biosphere model (L‐MEB). Three land surface variables were retrieved simultaneously from the multiangular and dual‐polarization TB data: surface soil moisture wg, vegetation optical depth τ, and surface temperature TS. The retrievals were obtained in two TS configurations: TS was either unknown or known with an uncertainty of 2 K. Applying these two assumptions, global maps of the estimated accuracy of the wg retrievals were produced, and the capability of the TB to monitor wg was evaluated. A sensitivity study was carried out in order to analyze the effect of the main parameters that may affect the retrieval accuracy: the fraction cover of open water and forests, frozen soil conditions, and the radiometric noise on TB. These results contribute to the better definition of the potential of the observations from future spaceborne missions such as the Soil Moisture and Ocean Salinity (SMOS) project.
Selective organic matter preservation in “burn‐down” turbidites on the Madeira Abyssal Plain
Authors: Prahl F. G. , Cowie G. L. , De Lange G. J. , Sparrow M. A.
Published: June 2003

Oxidized intervals of five organic‐rich Madeira Abyssal Plain (MAP) turbidites deposited during the Miocene, Pliocene, and Pleistocene all displayed comparable major loss of total organic carbon (TOC) (84 ± 3.1%) accompanied by a negative isotopic (δ13C) shift ranging from −0.3 to −2.9‰. Major but significantly lower loss of total nitrogen (Ntot, 61 ± 7.1%) also occurred, leading to a decrease in TOC relative to Ntot (C/Ntot) and a +1.3 to 2.7‰ Ntot isotopic (δ15N) shift. Compound specific isotopic measurements on plant wax n‐alkanes indicate the terrestrial organic component in the unoxidized deposits is 13C‐enriched owing to significant C4 contribution. Selective preservation of terrestrial relative to marine organic carbon could account for the δ13C behavior of TOC upon oxidation but only if a 13C‐depleted component of the bulk terrestrial signal is selectively preserved in the process. Although the C/Ntot decrease and positive δ15N shift seems inconsistent with selective terrestrial organic preservation, results from analysis of a Modern eolian dust sample collected in the vicinity indicate these observations are compatible. Regardless of the specific explanation for these isotopic observations, however, our findings provide evidence that paleoreconstruction of properties such as pCO2 using the δ13C of TOC is a goal fraught with uncertainty whether or not the marine sedimentary record considered is “contaminated” with significant terrestrial input. Nonetheless, despite major and selective loss of both marine and terrestrial components as a consequence of postdepositional oxidation, intensive organic geochemical proxies such as the alkenone unsaturation index, U37K′, appear resistant to change and thereby retain their paleoceanographic promise.
Influence of Northern Hemisphere climate and global sea level rise on the restricted Red Sea marine environment during termination I
Authors: Arz Helge W. , Pätzold Jürgen , Müller Peter J. , Moammar Mustafa O.
Published: June 2003

We present high‐resolution paleoceanographic records of surface and deep water conditions within the northern Red Sea covering the last glacial maximum and termination I using alkenone paleothermometry, stable oxygen isotopes, and sediment compositional data. Paleoceanographic records in the restricted desert‐surrounded northern Red Sea are strongly affected by the stepwise sea level rise and appear to record and amplify well‐known millennial‐scale climate events from the North Atlantic realm. During the last glacial maximum (LGM), sea surface temperatures were about 4°C cooler than the late Holocene. Pronounced coolings associated with Heinrich event 1 (∼2°C below the LGM level) and the Younger Dryas imply strong atmospheric teleconnections to the North Atlantic. Owing to the restricted exchange with the Indian Ocean, Red Sea salinity is particularly sensitive to changes in global sea level. Paleosalinities exceeded 50 psu during the LGM. A pronounced freshening of the surface waters is associated with the meltwater peaks MWP1a and MWP1b owing to an increased surface‐near inflow of “normal” saline water from the Indian Ocean. Vertical δ18O gradients are also increased during these phases, indicating stronger surface water stratification. The combined effect of deglacial changes in sea surface temperature and salinity on water column stratification initiated the formation of two sapropel layers, which were deposited under almost anoxic condition in a stagnant water body.
Simulations of Doppler spectra in the melting layer of precipitation
Authors: Skaropoulos Nikolaos C. , Russchenberg Herman W. J.
Published: June 2003

A new technique for simulating the full Doppler spectrum in the melting layer of precipitation is presented. Simulated results are shown to agree well with S‐band Doppler radar observations, despite the many simplifying assumptions used in the microphysical and scattering models. The technique has significant potential for radar studies of the melting layer.
Magnetostratigraphy of the Eldorado Mountains volcanic complex and the calibration of the early to middle Miocene polarity time scale
Authors: Wilson Douglas S. , Gans Phillip B.
Published: June 2003

Magnetic polarity measurements from a well dated (15.6–13.7 Ma) volcanic section in southern Nevada allow resolution of controversies in the calibration of the Middle Miocene polarity time scale. A sequence of lavas yielding exclusively reversed polarities dated at 15.5–14.9 Ma can be confidently identified as C5Br, and the C5Cn.ln(y) reversal is bracketed between 15.67 and 15.48 Ma (relative to TC = 27.92 Ma). Integration with other recent studies shows that polarity chrons C5Cr–C5ABr are now confidently correlated with lava flows dated from 16.9 to 13.4 Ma by the 40Ar/39Ar method.
Source process of the 3 November 2002 Denali fault earthquake (central Alaska) from teleseismic observations
Authors: Ozacar Arda A. , Beck Susan L. , Christensen Douglas H.
Published: June 2003

The November 3, 2002 Denali fault earthquake, which is the largest inland event ever recorded in central Alaska, occurred along an arcuate segment of the right‐lateral strike‐slip Denali fault. We use first‐motion P wave polarities and inversions of teleseismic P waveforms for a fixed focal mechanism to constrain the rupture process. We find clear evidence for a substantial reverse component near the hypocenter at the beginning of the rupture. Twenty‐five seconds later, rupture propagated unilaterally to the east on a strike‐slip fault and released most of the seismic moment along an asperity located 170 km east of the hypocenter with a maximum slip of 8 m. This earthquake had a duration of ∼120 s and ruptured more than 300 km in length. Correlation with gravity anomalies suggests a relation between moment distribution and physical properties of subsurface rock units that may support a weaker middle fault segment marked by fewer aftershocks.
Heat flow in the western Superior Province of the Canadian shield
Authors: Rolandone F. , Mareschal J. C. , Jaupart C. , Gosselin C. , Bienfait G. , Lapointe R.
Published: June 2003

We present new heat flow measurements from deep boreholes at 9 sites, northwest of Lake Superior, in Ontario. The new measurements drastically change the heat flow map in the Western Superior Province of the Canadian Shield. Previous maps relied heavily on shallow (2.5 m) measurements in sediments beneath small lakes and exhibited high heat flow anomalies (>60 mW m−2). The new heat flow values between 31 and 56 mW m−2 are well within the range of values in the eastern part of the Superior and in other Archean provinces.Without the shallow lake data, the mean heat flow from borehole measurements, including 9 previously published values, is 42 ± 8 mW m−2, which is close to the mean of other provinces in the Canadian Shield.
Pumice‐pumice collisions and the effect of the impact angle
Authors: Cagnoli B. , Manga M.
Published: June 2003

Using a high‐speed video camera, we studied oblique collisions of lapilli‐size pumice cylinders (with no rotation before impact) on flat pumice targets. Our results show that the rebound angle, the ratios of the components of velocities and the energy loss vary with the impact angle. In particular, in collisions with an average yaw angle approximately equal to zero, we observed relatively larger rebound angles at small and large impact angles and smaller values in between (the angles are measured from the horizontal surfaces of the targets). We observed also that the ratio of the normal components of velocities decreases and the ratio of the horizontal components increases when the impact angle increases. Furthermore, the ratio of the kinetic energy after to that before collisions, in general, decreases when the impact angle increases. Thus, our experiments reveal features that could be useful in modelling pumice‐pumice collisions in geophysical flows.
Multiple myeloma biology: lessons from the 5TMM models
Authors: Vanderkerken Karin , Asosingh Kewal , Croucher Peter , Van Camp Ben
Published: July 2003

Summary:  Multiple myeloma (MM) is a B cell neoplasm characterized by the monoclonal proliferation of plasma cells in the bone marrow, the development of osteolytic lesions and the induction of angiogenesis. These different processes require three‐dimensional interactions, with both humoral and cellular contacts. The 5TMM models are suitable models to study these interactions. These murine models originate from spontaneously developed myeloma in elderly mice, which are propagated by in vivo transfer of the myeloma cells into young syngeneic mice.

In this review we report on studies performed in the 5TMM models with special emphasis on the homing of the myeloma cells, the characterization of the migrating and proliferating clone and the identification of the isotype switch variants. The bone marrow microenvironment was further targeted with osteoprotegerin (OPG) to block the RANK/RANKL/OPG system and with potent bisphosphonates. Both treatments resulted in a significant protection against myeloma‐associated bone disease, and they decreased myeloma disease, as evidenced by a lower tumor load and an increased survival of the mice. These different studies demonstrate the strength of these models, not only in unraveling basic biological processes but also in the testing of potentially new therapeutic targets.
Homing of antibody secreting cells
Authors: Cyster Jason G.
Published: July 2003

Summary:  As activated B cells differentiate into plasma cells they complete a final series of migration steps that take them to locations where they can efficiently carry out their effector function, secreting immunoglobulin (Ig) M or IgG into circulation or releasing dimeric IgA adjacent to the epithelium for transcytosis. Recent experiments have established a key role for chemokines in directing antibody secreting cell (ASC) movement within the secondary lymphoid organs where they are generated, as well as in guiding the cells to the bone marrow or mucosal surfaces. This review discusses the chemokines involved in directing ASC movements, particularly focusing on the role of CXCR4 and CXCL12/SDF1. The function of CCR9 and CCR10 in IgA ASC homing and contributions made by integrins and lectins are also discussed.
Extrafollicular antibody responses
Authors: MacLennan Ian C. M. , Toellner Kai‐Michael , Cunningham Adam F. , Serre Karine , Sze Daniel M.‐Y. , Zúñiga Elina , Cook Matthew C. , Vinuesa Carola G.
Published: July 2003

Summary:  In adaptive antibody responses, B cells are induced to grow either in follicles where they form germinal centers or in extrafollicular foci as plasmablasts. Extrafollicular growth typically occurs in the medullary cords of lymph nodes and in foci in the red pulp of the spleen. It is not a feature of secondary lymphoid tissue associated with the internal epithelia of the body. All types of naïve and memory B cells can be recruited into extrafollicular responses. These responses are associated with immunoglobulin class switching but, at the most, only low‐level hypermutation.
Structural similarity in the absence of sequence homology of the messenger RNA export factors Mtr2 and p15
Authors: Fribourg Sébastien , Conti Elena
Published: July 2003

The association between Mtr2 and Mex67 is essential for the nuclear export of bulk messenger RNA in yeast. In metazoans, the analogous function is carried out by the TAP–p15 heterodimer. Whereas Mex67 and TAP are highly conserved proteins, their binding partners, Mtr2 and p15, share no sequence similarity, but are nevertheless functionally homologous. Here, we report the 2.8‐Å resolution crystal structure of Mtr2 in complex with the NTF2‐like domain of Mex67. Mtr2 is a novel member of the NTF2‐like family and interacts with Mex67, forming a complex with a similar structural architecture to that of TAP–p15. Mtr2 fulfils an analogous function to that of human p15 in maintaining the structural integrity of the heterodimer. In addition, Mtr2 presents a long internal loop, which contains residues that affect the export of the large ribosomal subunit.
Dimerization properties of a Xenopus laevis kinesin‐II carboxy‐terminal stalk fragment
Authors: De Marco Valeria , de Marco Ario , Goldie Kenneth N , Correia John J , Hoenger Andreas
Published: July 2003

We have analysed the structural and physical properties of the carboxy‐terminal stalk region of a kinesin‐II, Xenopus kinesin‐like protein 3A/B (Xklp3A/B), which we showed to be essential for heterodimerization in a previous work (De Marco et al., 2001). We expressed the corresponding A‐stalk and B‐stalk fragments and investigated their modes of interaction by analytical ultracentrifugation (AUC), circular dichroism spectroscopy, denaturation assays and electron microscopy. Co‐expression of the A‐stalk and B‐stalk produced the properly folded, hetero‐dimeric coiled coil at high yields. The dimeric nature of the complex was confirmed by AUC. We also found that the isolated A‐stalk fragment forms a stable helix by itself and shows a significant tendency towards homodimer and higher‐order complex formation. In the absence of the corresponding A‐stalk fragment, the isolated B‐stalk fragment remains partially unfolded, which suggests that the A‐stalk provides a template structure for the B‐stalk in order to recompose the complete heterodimeric coiled coil.
DNA replication: a complex matter
Authors: Frouin Isabelle , Montecucco Alessandra , Spadari Silvio , Maga Giovanni
Published: July 2003

In eukaryotic cells, the essential function of DNA replication is carried out by a network of enzymes and proteins, which work together to rapidly and accurately duplicate the genetic information of the cell. Many of the components of this DNA replication apparatus associate with other cellular factors as components of multiprotein complexes, which act cooperatively in networks to regulate cell cycle progression and checkpoint control, but are distinct from the pre‐replication complexes that associate with the origins and regulate their firing. In this review, we summarize current knowledge about the composition and dynamics of these large multiprotein complexes in mammalian cells and their relationships to the replication factories.
Regulating mammalian checkpoints through Cdc25 inactivation
Authors: Donzelli Maddalena , Draetta Giulio F
Published: July 2003

Precise monitoring of DNA replication and chromosome segregation ensures that there is accurate transmission of genetic information from a cell to its daughters. Eukaryotic cells have developed a complex network of checkpoint pathways that sense DNA lesions and defects in chromosome segregation, spindle assembly and the centrosome cycle, leading to an inhibition of cell‐cycle progression for the time required to remove the defect and thus preventing genomic instability. The activation of checkpoints that are responsive to DNA damage or incomplete DNA replication ultimately results in the inhibition of cyclin‐dependent kinases. This review focuses on our understanding of the biochemical mechanisms that specifically inactivate Cdc25 (cell division cycle 25) phosphatases to achieve this. The evidence for links between checkpoint deregulation and oncogenesis is discussed.
Inflammatory bowel disease after liver transplantation: the effect of different immunosuppressive regimens
Authors: Haagsma E. B. , Van Den Berg A. P. , Kleibeuker J. H. , Slooff M. J. H. , Dijkstra G.
Published: July 2003

Background : Seemingly conflicting results have been reported on the prevalence and severity of inflammatory bowel disease after liver transplantation. Regimens with different combinations of drugs can be used for immunosuppression after transplantation.

Aim : To study retrospectively the prevalence of inflammatory bowel disease after liver transplantation, and the possible relationship with maintenance immunosuppressive regimens.

Methods : All 78 patients with end‐stage primary sclerosing cholangitis (48 patients) or autoimmune cirrhosis (30 patients), transplanted between 1979 and July 2001, and with a follow‐up of at least 1 year, were eligible for this study. In addition to patient and transplant characteristics, data on inflammatory bowel disease and immunosuppression before and after transplantation were collected. The Kaplan–Meier method was used for survival analysis. Possible risk factors for inflammatory bowel disease after transplantation were analysed by Cox univariate and multivariate regression.

Results : The median follow‐up after transplantation was 7.2 years (range, 1.1–22.3 years). Nine of 25 patients with pre‐transplant inflammatory bowel disease experienced flare‐ups after transplantation. Six of 53 patients without pre‐transplant inflammatory bowel disease developed de novo inflammatory bowel disease after transplantation. The cumulative risks (standard errors in parentheses) for inflammatory bowel disease were 6% (3%), 12% (4%) and 20% (5%) at 1, 3 and 5 years after transplantation, respectively. The inflammatory bowel disease‐free survival was significantly higher in patients not receiving tacrolimus vs. those receiving tacrolimus, in patients receiving azathioprine vs. those not receiving azathioprine and in patients taking the regimen prednisolone–azathioprine–ciclosporin A vs. those taking tacrolimus–prednisolone. Pre‐transplant inflammatory bowel disease and the use of tacrolimus were found to be independent predictors for inflammatory bowel disease after transplantation.

Conclusions : The prevalence of inflammatory bowel disease after liver transplantation is affected by the immunosuppression used. Azathioprine seems to have a protective effect and tacrolimus a promoting effect.
The effect of metoclopramide on QT dynamicity: double‐blind, placebo‐controlled, cross‐over study in healthy male volunteers
Authors: Elli̇dokuz E. , Kaya D.
Published: July 2003

Background : Metoclopramide, a central and peripheral dopamine type 2 receptor antagonist, has been used as an attractive and safer alternative to cisapride. However, cardiac side‐effects have also been reported with this drug.

Aim : To evaluate the effects of intravenous metoclopramide administration on cardiac repolarization using QT dynamicity, a reliable indicator of arrhythmic side‐effects.

Methods : The effect of metoclopramide on cardiac repolarization was evaluated in 10 healthy male volunteers in the supine position. Metoclopramide (10 mg) or placebo was administered intravenously at random in a double‐blind, cross‐over manner to the participants during continuous electrocardiographic recording in the supine position. The 30‐min stationary segments of the recordings before and after drug administration were used to investigate QT dynamicity.

Results : Metoclopramide administration, but not placebo, resulted in steeper QT/RR slopes compared with the pre‐drug values (metoclopramide: 0.037 ± 0.004 vs. 0.064 ± 0.012; P = 0.041; placebo: 0.045 ± 0.006 vs. 0.050 ± 0.004; P = 0.563). In a two‐way analysis of variance model, metoclopramide administration also increased the QT variance independently (F = 6.225, P = 0.023).

Conclusions : Metoclopramide administration increases the QT/RR slope and QT variance. These findings may partly explain the underlying mechanism of ventricular arrhythmias associated with metoclopramide.
Tachykinins and their possible modulatory role on testicular function: a review
Authors: Debeljuk Luciano , Rao Jaladanki N. , Bartke Andrzej
Published: July 2003

Tachykinins are vasoactive and smooth muscle‐contracting peptides with widespread localizations. Tachykinins have been localized in the nerve fibres that supply the testes, in the Leydig cells of different animal species, and also in Sertoli cells of the Siberian hamster testes. The presence of substance P (SP) has also been demonstrated in ejaculated human spermatozoa and in the seminal plasma. Tachykinins have been shown to inhibit the release of testosterone by testicular fragments or by isolated Leydig cells in vitro. Acting on Sertoli cells, tachykinins have been shown to stimulate the release of lactate and transferrin by these cells in vitro, and also to stimulate aromatase activity.

Leydig and Sertoli cells express the Preprotachykinin A gene, and this fact strongly suggests that tachykinins can be synthesized in the testes. These findings suggest that tachykinins may have a physiological function in the testes as modulators of the functions of the different cell types contained in these organs.
Analysis of factors associated with multinucleate formation in human IVF
Authors: Shibahara Hiroaki , Yamanaka Hiroko , Hirano Yuki , Kikuchi Kumiko , Yamanaka Seiji , Suzuki Tatsuya , Takamizawa Satoru , Suzuki Mitsuaki
Published: July 2003

This study was carried out to analyse if some of the sperm parameters assessed by computer‐aided sperm analysis (CASA) are associated with multinucleate formation in human in vitro fertilization (IVF). In the present study, 137 IVF‐embryo transfer (ET) treatment cycles in which pronucleate formation could be observed were enrolled. Sperm parameters after swim‐up were assessed using CASA and strict criteria. Thirty‐two (2.3%) of 1368 oocytes fertilized were judged as multinucleate formation, which occurred in 25 of 137 IVF‐ET treatment cycles, giving the incidence of 18.2%. The factors associated with multinucleate formation were analysed. There were significant differences of the numbers of oocytes collected (13.9 vs. 9.2; p = 0.028), fertilization rate (88.8% vs. 71.9%; p = 0.011), curvilinear velocity (VCL) (162.7 μm/sec vs. 149.1 μm/sec; p = 0.034), average path velocity (VAP) (100.3 μm/sec vs. 93.1 μm/sec; p = 0.016), and amplitude of lateral head displacement (ALH) (5.9 μm vs. 5.3 μm; p = 0.046) between 25 cycles with multipronucleate formation and 112 cycles with two pronucleate formations. However, there were no significant differences of women's age or the number of sperm inseminated between the two groups. These findings suggest that prediction of multinucleate formation in human IVF might be possible in patients when the number of oocytes collected is higher and sperm motility parameters after swim‐up are faster. However, prevention of multinucleate formation seems to be unnecessary because a higher successful IVF‐ET outcome is expected as a result of the excellent fertilization rate in these patients.
Isolation and characterization of a human sperm antigen gene h‐Sp‐1
Authors: Kanazawa Ri‐Ichiro , Komori Shinji , Sakata Kazuko , Tanaka Hiroyuki , Sawai Hideaki , Tsuji Yoshiyuki , Koyama Koji
Published: July 2003

We isolated and characterized a human sperm antigen gene (h‐Sp‐1) from human testis complementary DNA using antiserum against the human sperm membrane. Northern blot analysis detected two transcripts (2.3 and 1.1 kb) of the h‐Sp‐1 gene. The 2.3‐kb transcript is ubiquitous, whereas the 1.1‐kb transcript is specific to the human testis with a high level of expression. Determination of the base sequence of h‐Sp‐1 showed a size of 2170 bp and 43.4% homology with human synaptophysin. The base sequence indicates a molecule consisting of 259 amino acids, with four hydrophilic and four hydrophobic regions. In order to further characterize the h‐Sp‐1 molecule, we synthesized the probable region of amino acids with high antigenicity based on the amino acid sequence (amino acid nos. 174–198) and immunized rabbits to prepare an antiserum. In our experimental model of fertilization between human sperm and zona pellucida‐free hamster ova, partial inhibition of fertilization was observed. We were able to synthesize a large quantity of recombinant protein by inserting the h‐Sp‐1 gene into a baculovirus vector and infecting spodoptera frugiperda culture cells (sf9 insect cells). The synthesized protein had a molecular weight of 30 kDa. We then immunized Balb/c mice with this protein to prepare a monoclonal antibody (G3G9), which was used to localize the h‐Sp‐1 molecule in sperm and tissues (e.g. testis). The h‐Sp‐1 molecule was present in the cell membrane from the head to tail of human sperm. Staining of the testis and epididymis also showed h‐Sp‐1 to be present in spermatogonia, spermatocyte, sperm and epididymal duct epithelium. These findings suggest that the h‐Sp‐1 molecule is expressed in sperm and testes and plays a role in fertilization.
Meiotic segregation of sex chromosomes in mosaic and non‐mosaic XYY males: case reports and review of the literature
Authors: Rives N. , Siméon N. , Milazzo J. P. , Barthélémy C. , Macé B.
Published: July 2003

The aim of this study was to determine the incidence of sex chromosome aneuploidy in spermatozoa of two males with a 47,XYY karyotype and one male with a 46,XY/47,XYY constitution. Spermatozoa obtained from two oligospermic patients and one volunteer semen donor were studied by multicolour fluorescence in situ hybridization. In the XY/XYY male, the frequencies of X‐bearing to Y‐bearing sperm were significantly different from the 1 : 1 expected ratio. Significantly increased frequencies were found in the mosaic and non‐mosaic males for 24,XX and 24,YY sperm when compared with control donors. The number of 24,XY sperm was significantly different from the controls in the XYY males, but not in the mosaic male. The incidence of disomy 18 and the rate of diploidy also increased in the three patients. However, the mosaic male had the lowest cumulative rate of disomic and diploid spermatozoa when compared with the two XYY patients. Our data suggest that: (i) chromosome abnormalities observed in spermatozoa of the two XYY oligoasthenoteratospermic (OAT) males arise through segregation errors in XY germ cells rather than normal meiosis of XYY germ cells, (ii) mosaic XYY males with normal semen parameters have a lower risk of producing offspring with a sex chromosomal abnormality than OAT males with XYY karyotype.
Cavernosal tissue nitrite, nitrate, malondialdehyde and glutathione levels in diabetic and non‐diabetic erectile dysfunction
Authors: Tuncayengin Alper , Biri Hasan , Onaran Metin , Şen İlker , Tuncayengin Özlem , Polat Fevzi , Erbaş Deniz , Bozkirli İbrahim
Published: July 2003

The aim of this study is to investigate the role of nitric oxide (NO) stabile end products, membrane lipid peroxidation and antioxidant defensive mechanism in diabetic erectile dysfunction (ED) and compare these parameters with non‐diabetic ED groups. We examined the penile cavernosal tissues, obtained from 22 patients who had undergone surgery of penile prostheses implantation, for the nitrite, nitrate, malondialdehyde (MDA) and glutathione (GSH) levels. Eight patients were suffering from diabetic erectile dysfunction (ED) and 14 patients had non‐diabetic ED. Nitrite and nitrate levels were lower; MDA and GSH levels were higher in the diabetic group. There were statistically significant differences between diabetic and non‐diabetic groups amongst the nitrite (p < 0.001), nitrate (p < 0.01), MDA (p < 0.001) and GSH (p < 0.01) levels. Our data provide evidence that NO deficiency, possibly due to the membrane lipid peroxidation and defective antioxidant defensive mechanism, may contribute to the development of diabetic ED and thus is involved in the pathogenesis of ED in diabetic patients.
Morphometric Investigations of Breed‐Specific Features in Feline Skulls and Considerations on their Functional Implications
Authors: Künzel W. , Breit S. , Oppel M.
Published: July 2003

A total of 17 parameters (nine lengths, four heights, four widths) was used to characterize the shape of the skull in a sample of 69 pure bred cats. Results of the discriminant analysis confirmed three phenotypically different skull formations, i.e. the round‐shaped, the triangular and the cuneiform. Further statistical analyses revealed that the appearance of the skull was especially variable in the case of a round shape and that the lengths had been especially affected by these characteristics. The round shape of the brachycephalic skull was attributed to a reduction in length of the face and braincase as well. In many cases, this condition was associated with disproportional increase in height and width of the braincase and an increase in convexity of the calvaria. The decrease in length of the face was more pronounced at the dorsal surface of the nose than at the palate. Therefore, the inclination of the bony nasal aperture became flatter and the inclination of the maxilloturbinate became steeper. As a result, the ventral nasal meatus changed its direction twice. This condition might predispose to dyspnoea by restricting the air passageways within the nasal cavity. Round‐shaped skulls were also associated with a decrease in facial width. Morphological variants that were frequently seen in round‐shaped skulls include almost rectangular inclination of the nasal bone and more distant extension of the foramen magnum between the occipital condyles.
The peri‐albumen layer: a novel structure in the envelopes of an avian egg
Authors: Sultana F. , Yokoe A. , Ito Y. , Mao K. M. , Yoshizaki N.
Published: July 2003

The present paper describes a novel structure, termed the peri‐albumen layer, in the egg‐envelopes of the quail Coturnix japonica. It reacts with Alcian blue and exists between the egg white and the shell membrane. Ultrastructurally, it is of fine granular structure and forms a fenestrate sheet, the width of which is 190 nm or less. Isolated materials of the peri‐albumen layer include an Alcian‐blue‐positive polysaccharide of 260 kDa, and three glycoproteins of 160, 108 and 52 kDa. The layer is supplied to an egg when it passes through the magnum–isthmus junction, the normalized length of which is 0.62–0.63 of the oviduct. The mucosa of the junction consists exclusively of a luminal epithelium. It is apparently distinct from the mucosa of the magnum and the isthmus, which consist of a luminal epithelium and tubular glands. The luminal epithelium of the magnum–isthmus junction stains prominently with Alcian blue and consists of alternately distributed ciliated cells and granular cells. Immunohistochemistry with an antiserum raised against the materials of the peri‐albumen layer revealed the staining of the peri‐albumen layer of the egg, and secretory cells of the luminal epithelium at the magnum–isthmus junction. It was concluded that the materials of the peri‐albumen layer are produced by secretory cells at the magnum–isthmus junction of the oviduct.