Showing papers by "Martin Luther University of Halle-Wittenberg published in 2002"

Slater-Pauling behavior and origin of the half-metallicity of the full-Heusler alloys

Abstract: Using the full-potential screened Korringa-Kohn-Rostoker method we study the full-Heusler alloys based on Co, Fe, Rh, and Ru. We show that many of these compounds show a half-metallic behavior; however, in contrast to the half-Heusler alloys the energy gap in the minority band is extremely small due to states localized only at the Co (Fe, Rh, or Ru) sites which are not present in the half-Heusler compounds. The full-Heusler alloys show a Slater-Pauling behavior and the total spin magnetic moment per unit cell ${(M}_{t})$ scales with the total number of valence electrons ${(Z}_{t})$ following the rule ${M}_{t}{=Z}_{t}\ensuremath{-}24.$ We explain why the spin-down band contains exactly 12 electrons using arguments based on group theory and show that this rule holds also for compounds with less than 24 valence electrons. Finally we discuss the deviations from this rule and the differences compared to the half-Heusler alloys.

Germ-line mutations in nonsyndromic pheochromocytoma.

Abstract: Background The group of susceptibility genes for pheochromocytoma that included the proto-oncogene RET (associated with multiple endocrine neoplasia type 2 [MEN-2]) and the tumor-suppressor gene VHL (associated with von Hippel–Lindau disease) now also encompasses the newly identified genes for succinate dehydrogenase subunit D (SDHD) and succinate dehydrogenase subunit B (SDHB), which predispose carriers to pheochromocytomas and glomus tumors. We used molecular tools to classify a large cohort of patients with pheochromocytoma with respect to the presence or absence of mutations of one of these four genes and to investigate the relevance of genetic analyses to clinical practice. Methods Peripheral blood from unrelated, consenting registry patients with pheochromocytoma was tested for mutations of RET, VHL, SDHD, and SDHB. Clinical data at first presentation and follow-up were evaluated. Results Among 271 patients who presented with nonsyndromic pheochromocytoma and without a family history of the disease,...

Central role of Drosophila SU(VAR)3-9 in histone H3-K9 methylation and heterochromatic gene silencing.

Abstract: Su(var)3–9 is a dominant modifier of heterochromatin-induced gene silencing. Like its mammalian and Schizosaccharomyces pombe homologues, Su(var) 3–9 encodes a histone methyltransferase (HMTase), which selectively methylates histone H3 at lysine 9 (H3-K9). In Su(var)3–9 null mutants, H3-K9 methylation at chromocentre heterochromatin is strongly reduced, indicating that SU(VAR)3–9 is the major heterochromatin-specific HMTase in Drosophila. SU (VAR)3–9 interacts with the heterochromatin-associated HP1 protein and with another silencing factor, SU(VAR)3–7. Notably, SU(VAR)3–9–HP1 interaction is interdependent and governs distinct localization patterns of both proteins. In Su(var)3–9 null mutants, concentration of HP1 at the chromocentre is nearly lost without affecting HP1 accumulation at the fourth chromosome. By contrast, in HP1 null mutants SU(VAR)3–9 is no longer restricted at heterochromatin but broadly dispersed across the chromosomes. Despite this interdependence, Su(var)3–9 dominates the PEV modifier effects of HP1 and Su(var)3–7 and is also epistatic to the Y chromosome effect on PEV. Finally, the human SUV39H1 gene is able to partially rescue Su(var)3–9 silencing defects. Together, these data indicate a central role for the SU(VAR)3–9 HMTase in heterochromatin-induced gene silencing in Drosophila.

Origin and properties of the gap in the half-ferromagnetic Heusler alloys

Abstract: We study the origin of the gap and the role of chemical composition in the half-ferromagnetic Heusler alloys using the full-potential screened Korringa-Kohn-Rostoker method. In the paramagnetic phase the ${C1}_{b}$ compounds, like NiMnSb, present a gap. Systems with 18 valence electrons, ${Z}_{t},$ per unit cell, like CoTiSb, are semiconductors, but when ${Z}_{t}g18,$ antibonding states are also populated, thus the paramagnetic phase becomes unstable and the half-ferromagnetic one is stabilized. The minority occupied bands accommodate a total of nine electrons and the total magnetic moment per unit cell in ${\ensuremath{\mu}}_{B}$ is just the difference between ${Z}_{t}$ and $2\ifmmode\times\else\texttimes\fi{}9.$ While the substitution of the transition metal atoms may preserve the half-ferromagnetic character, substituting the sp atom results in a practically rigid shift of the bands and the loss of half-metallicity. Finally we show that expanding or contracting the lattice parameter by 2% preserves the minority-spin gap.

Mapping of quantitative trait loci determining agronomic important characters in hexaploid wheat ( Triticum aestivum L.).

Abstract: A set of 114 recombinant inbred lines of the 'International Triticeae Mapping Initiative' mapping population was grown during the seasons 1997, 1998, 1999 and 2000 under several environments. Twenty morphological (glume colour, awn colour, waxiness, leaf erectness, peduncle length), agronomical (ear emergence time, flowering time, grain filling time, ear length, plant height, lodging, grain number, thousand-grain-weight, grain weight per ear, grain protein content, winter hardiness) and disease resistance (powdery mildew, yellow rust, leaf rust, fusarium) traits were studied. Not all traits were scored in each experiment. In total 210 QTLs with a LOD threshold of >2.0 (minor QTLs) were detected of which 64 reached a LOD score of >3.0 (major QTLs). Often QTLs were detected in comparable positions in different experiments. Homologous and homoeologous relationships of the detected QTLs, and already described major genes or QTLs determining the same traits in wheat or other Triticeae members, are discussed.

Supersymmetry Breaking and α′-Corrections to Flux Induced Potentials

Abstract: We obtain the vacuum solutions for M-theory compactified on eight-manifolds with non-vanishing four-form flux by analyzing the scalar potential appearing in the three-dimensional theory. Many of these vacua are not supersymmetric and yet have a vanishing three-dimensional cosmological constant.We show that in the context of type-IIB compactifications on Calabi-Yau threefolds with fluxes and external brane sources α'-corrections generate a correction to the supergravity potential proportional to the Euler number of the internal manifold which spoils the no-scale structure appearing in the classical potential. This indicates that α'-corrections may indeed lead to a stabilization of the radial modulus appearing in these compactifications.

Human Dcp2: a catalytically active mRNA decapping enzyme located in specific cytoplasmic structures

Abstract: We have cloned cDNAs for the human homologues of the yeast Dcp1 and Dcp2 factors involved in the major (5′–3′) and NMD mRNA decay pathways. While yeast Dcp1 has been reported to be the decapping enzyme, we show that recombinant human Dcp2 (hDcp2) is enzymatically active. Dcp2 activity appears evolutionarily conserved. Mutational and biochemical analyses indicate that the hDcp2 MutT/Nudix domain mediates this activity. hDcp2 generates m7GDP and 5′-phosphorylated mRNAs that are 5′–3′ exonuclease substrates. Corresponding decay intermediates are present in human cells showing the relevance of this activity. hDcp1 and hDcp2 co-localize in cell cytoplasm, consistent with a role in mRNA decay. Interestingly, these two proteins show a non-uniform distribution, accumulating in specific foci.

Pattern of Nodal Metastasis for Primary and Reoperative Thyroid Cancer

Abstract: This retrospective investigation was undertaken to clarify the pattern of nodal metastasis in papillary (PTC) and medullary (MTC) thyroid carcinoma. Nodal metastases are associated with recurrence of both PTCs and MTCs. The extent of lymph node dissection is controversial owing to the lack of reliable diagnostic criteria for nodal metastases other than histopathology. Between November 1994 and October 1999 a total of 296 patients (134 PTCs, 162 MTCs) underwent total thyroidectomy in conjunction with a standard resection of at least the cervicocentral lymph node compartment. Of 10,446 sampled lymph nodes, 1641 were positive. All nodes were related to their respective cervicomediastinal compartments. The ipsilateral cervicolateral compartment was involved almost as often as the cervicocentral compartment in primary PTC (29% vs. 32%), reoperative PTC (21% vs. 37%), primary MTC (34% vs. 34%), and reoperative MTC (49% vs. 65%). The contralateral cervicolateral and mediastinal compartments were more rarely affected, and were least affected in the primary setting. From these data was derived an individualized surgical strategy for PTC and MTC. This concept rests on the joint resection of cervicocentral and ipsilateral cervicolateral compartments. Depending on tumor entity, surgical status, and primary tumor diameter, additional compartments may have to be cleared.

Plant rhizodeposition — an important source for carbon turnover in soils

Abstract: The soil organic matter plays a key role in ecological soil functions, and has to be considered as an important CO2 sink on a global scale. Apart from crop residues (shoots and roots), left over on the field after harvest, carbon and nitrogen compounds are also released by plant roots into the soil during vegetation, and undergo several transformation processes. Up to now the knowledge about amount, composition, and turnover of these root-borne compounds is still very limited. So far it could be demonstrated with different plant species, that up to 20 % of photosynthetically fixed C are released into the soil during vegetation period. These C amounts are ecological relevant. Depending on assimilate sink strength during ontogenesis, the C release varies with plant age. A large percentage of these root-borne substances were rapidly respired by microorganisms (64—86 %). About 2—5 % of net C assimilation was kept in soil. The root exudates of maize were mainly water-soluble (79 %), and in this fraction about 64 % carbohydrates, 22 % amino acids/amides and 14 % organic acids could be identified. Plant species and in some cases also plant cultivars varied strongly in their root exudation pattern. Under non-sterile conditions the exuded compounds were rapidly stabilized in water-insoluble forms and bound preferably to the soil clay fraction. The binding of root exudates to soil particles also improved soil structure by increasing aggregate stability. Future research should focus on quantification and characterization of root-borne C compounds during the whole plant ontogenesis. Apart from pot experiments with 14CO2 labeling, it is necessary to conduct model field experiments with 13CO2 labeling in order to be able to distinguish between CO2 originating from the soil C pool and rhizosphere respiration, originating from plant assimilates. Such a separation is necessary to assess if soils are sources or sinks of CO2. The incorporation of root-borne C (14C, 13C) into soil organic matter of different stability is also of particular interest. Pflanzliche Rhizodeposition — eine wichtige Quelle fur den Kohlenstoffumsatz in Boden Die organische Bodensubstanz (OBS) nimmt eine Schlusselrolle bei den okologischen Bodenfunktionen ein und stellt global betrachtet eine wichtige CO2-Senke dar. Neben den auf dem Feld verbleibenden Ernte- und Wurzelruckstanden werden C- und N-Verbindungen auch wahrend des Pflanzenwachstums in den Boden abgegeben und unterliegen dort vielfaltigen Umsetzungsprozessen. Der Kenntnisstand uber die Menge, Zusammensetzung und den Umsatz dieser wurzelburtigen Verbindungen im Boden ist noch sehr begrenzt. Daher beschaftigt sich die vorliegende Publikation mit der Rhizodeposition als wichtiger Quelle des C-Umsatzes in Boden, insbesondere mit den mobilen Wurzelabscheidungen. Bisher konnte anhand verschiedener Pflanzenarten gezeigt werden, dass bis zu 20 % des photosynthetisch fixierten C wahrend der Vegetation durch die Wurzeln freigesetzt werden. Es handelt sich dabei um okologisch relevante C-Mengen. In Abhangigkeit von der Starke des Assimilatsinks wahrend der Ontogenese variiert die C-Freisetzung mit dem Pflanzenalter. Ein hoher Anteil dieser wurzelburtigen Verbindungen (64—86 %) wurde schnell durch Mikroorganismen veratmet. 2—5 % der Netto-C-Fixierung blieben im Boden zuruck. Dieser Bodenruckstand war bei Wurzelabscheidungen von Mais hauptsachlich wasserloslich (79 %), und in dieser Fraktion wurden 64 % Kohlenhydrate, 22 % Aminosauren/Amide und 14 % organische Sauren identifiziert. Pflanzenarten und teilweise auch -sorten variierten stark in der Zusammensetzung ihrer Wurzelexsudate. Unter insterilen Bedingungen wurden die exsudierten Verbindungen schnell in nichtwasserloslicher Form stabilisiert und vor allem an die Tonfraktion des Bodens gebunden. Die Bindung an Bodenpartikel verbesserte die Bodenstruktur durch erhohte Aggregatstabilitat. Zukunftige Forschungsarbeiten sollten sich auf die Quantifizierung und Charakterisierung wurzelburtiger C-Verbindungen wahrend der gesamten pflanzlichen Ontogenese konzentrieren. Abgesehen von Gefasversuchen mit 14CO2-Applikation ist es erforderlich, Feldmodellversuche mit 13CO2-Applikation durchzufuhren, um zwischen der CO2-Emission aus dem Boden-C-Pool und derjenigen aus der Rhizospharenatmung (Ursprung sind Pflanzenassimilate) unterscheiden zu konnen. Eine solche Trennung ist zur Beurteilung, ob Boden eine Quelle oder Senke fur CO2 darstellen, zwingend erforderlich. Von besonderem Interesse ist auch der Einbau des wurzelburtigen C (14C, 13C) in OBS-Fraktionen unterschiedlicher Stabilitat.

Knowledge Management Systems

Abstract: Knowledge management systems , Knowledge management systems , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Mirror Symmetry in Generalized Calabi-Yau Compactifications

Abstract: We discuss mirror symmetry in generalized Calabi-Yau compactifications of type II string theories with background NS fluxes. Starting from type IIB compactified on Calabi-Yau threefolds with NS three-form flux we show that the mirror type IIA theory arises from a purely geometrical compactification on a different class of six-manifolds. These mirror manifolds have SU(3) structure and are termed half-flat; they are neither complex nor Ricci-flat and their holonomy group is no longer SU(3). We show that type IIA appropriately compactified on such manifolds gives the correct mirror-symmetric low-energy effective action.

NO- and haem-independent activation of soluble guanylyl cyclase: molecular basis and cardiovascular implications of a new pharmacological principle

Abstract: 1. Soluble guanylyl cyclase (sGC) is the only proven receptor for the ubiquitous biological messenger nitric oxide (NO) and is intimately involved in many signal transduction pathways, most notably in regulating vascular tone and platelet function. sGC is a heterodimeric (alpha/ss) protein that converts GTP to cyclic GMP; NO binds to its prosthetic haem group. Here, we report the discovery of a novel sGC activating compound, its interaction with a previously unrecognized regulatory site and its therapeutic implications. 2. Through a high-throughput screen we identified BAY 58-2667, an amino dicarboxylic acid which potently activates sGC in an NO-independent manner. In contrast to NO, YC-1 and BAY 41-2272, the sGC stimulators described recently, BAY 58-2667 activates the enzyme even after it has been oxidized by the sGC inhibitor ODQ or rendered haem deficient. 3. Binding studies with radiolabelled BAY 58-2667 show a high affinity site on the enzyme. 4. Using photoaffinity labelling studies we identified the amino acids 371 (alpha-subunit) and 231 - 310 (ss-subunit) as target regions for BAY 58-2667. 5. sGC activation by BAY 58-2667 results in an antiplatelet activity both in vitro and in vivo and a potent vasorelaxation which is not influenced by nitrate tolerance. 6. BAY 58-2667 shows a potent antihypertensive effect in conscious spontaneously hypertensive rats. In anaesthetized dogs the hemodynamic effects of BAY 58-2667 and GTN are very similar on the arterial and venous system. 7. This novel type of sGC activator is a valuable research tool and may offer a new approach for treating cardiovascular diseases.

The German version of the Oral Health Impact Profile – translation and psychometric properties

Abstract: The need for cross-culturally adapted oral-health specific health outcome measures is increasingly recognized in Germany. Following accepted cultural adaptation technique guidelines, we report the development of the German version of the Oral Health Impact Profile (OHIP). The original 49 items were translated using a forward-backward method. A de novo development of German items established content validity. A priori hypothesized associations between the OHIP summary score and self-reported oral health and five oral disorders were confirmed in a random sample of the general population (n = 163, age 20-60 yr). These associations were interpreted as support for construct validity. The instrument's responsiveness, as indicated by a mean OHIP summary score change from 45.0 to 28.3, was established in 67 consecutive patients treated for temporomandibular disorder pain (age 19-85 yr; 72% women). Test-retest reliability was demonstrated by intraclass correlation coefficients of 0.63-0.92 for dimensions and summary scores (convenience sample, n = 30, age 18-85 yr; 53% women). Internal consistency was high (Cronbach's alpha > 0.74). Sufficient discriminative and evaluative psychometric properties of the Oral Health Impact Profile German version (OHIP-G) make the instrument suitable for assessment of oral health-related quality of life in cross-sectional as well as longitudinal studies.

Mutant chromatin remodeling protein SMARCAL1 causes Schimke immuno-osseous dysplasia.

Abstract: Schimke immuno-osseous dysplasia (SIOD, MIM 242900) is an autosomal-recessive pleiotropic disorder with the diagnostic features of spondyloepiphyseal dysplasia, renal dysfunction and T-cell immunodeficiency. Using genome-wide linkage mapping and a positional candidate approach, we determined that mutations in SMARCAL1 (SWI/SNF2-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1), are responsible for SIOD. Through analysis of data from persons with SIOD in 26 unrelated families, we observed that affected individuals from 13 of 23 families with severe disease had two alleles with nonsense, frameshift or splicing mutations, whereas affected individuals from 3 of 3 families with milder disease had a missense mutation on each allele. These observations indicate that some missense mutations allow retention of partial SMARCAL1 function and thus cause milder disease.

Getting across--bacterial type III effector proteins on their way to the plant cell.

Abstract: Pathogenicity of most Gram-negative bacterial plant pathogens depends on hrp (hypersensitive response and pathogenicity) genes, which control the ability to cause disease and to elicit specific defense responses in resistant plants. hrp genes encode a specialized type III secretion (TTS) system that mediates the vectorial delivery of bacterial effector proteins across both bacterial membranes as well as across the eukaryotic plasma membrane into the host cell cytosol. One well-studied effector protein is AvrBs3 from Xanthomonas campestris pv. vesicatoria, the causal agent of bacterial spot in pepper and tomato. AvrBs3 induces hypertrophy symptoms in susceptible plants and triggers a resistance gene-specific cell death reaction in resistant plants. Intriguingly, AvrBs3 has characteristic features of eukaryotic transcription factors, suggesting that it modulates the host's transcriptome. Here, we discuss the TTS system of X.campestris pv. vesicatoria in the light of current knowledge on type III-dependent protein secretion in plant pathogenic bacteria.

Iatrogenic ruptures of the tracheobronchial tree

Abstract: Objective: Iatrogenic tracheobronchial ruptures are seldom but severe complications after intubation or bronchoscopy. Therefore, we evaluated the reasons, the subsequent therapy and the outcome of patients with tracheal rupture, who were admitted to our hospital. Methods: In a retrospective study we examined 19 patients (15 women, four men; 43–87 years) treated for acute tracheobronchial lesions. Eleven (58%) patients had a tracheobronchial rupture by single-lumen tube, four (21%) by double-lumen tube and two patients (10%) by tracheal cannula. A total of 47% of whom were carried out under emergency conditions. Two patients had a rupture due to a stiff bronchoscopy. Mean symptoms were mediastinal and subcutaneous emphysema. Two emergency collar incisions had been done. Results: The localization of ruptures was in all cases in the paries membranaceus, length: 1–7 cm (mean: 4.8 cm). The interval between the onset of symptoms and the diagnose differed widely (up to 72 h), nine (47%) diagnoses were made during intubation/bronchoscopy. One patient, with a small tear (1 cm) was treated conservatively with fibrin-glue. The other 18 patients had surgical repair through a thoracotomy. The postoperative mortality was determined with 42%, which was not dependent on the rupture but basically by the underlying diseases requiring intubation. Conclusions: Iatrogenic tracheal rupture is a dangerous complication with potentially high postoperative mortality, mostly influenced by the underlying disease. Early surgical repair must be the preferred treatment. q 2002 Elsevier Science B.V. All rights reserved.

The xanthomonas type III effector protein AvrBs3 modulates plant gene expression and induces cell hypertrophy in the susceptible host.

Abstract: Xanthomonas campestris pv. vesicatoria bacteria expressing the type III effector protein AvrBs3 induce a hypersensitive response in pepper plants carrying the resistance gene Bs3. Here, we report that infection of susceptible pepper and tomato plants leads to an AvrBs3-dependent hypertrophy of the mesophyll tissue. Agrobacterium-mediated transient expression of the avrBs3 gene in tobacco and potato plants resulted in a similar phenotype. Induction of hypertrophy was shown to depend on the repeat region, nuclear localization signals, and acidic transcription activation domain (AAD) of AvrBs3, suggesting that the effector modulates the host's transcriptome. To search for host genes regulated by AvrBs3 in an AAD-dependent manner, we performed a cDNA-amplified fragment length polymorphism analysis of pepper mRNA populations. Thirteen AvrBs3-induced transcripts were identified and confirmed by reverse transcriptase-polymerase chain reaction. Sequence analysis revealed homologies to auxin-induced and expansinlike genes, which play a role in cell enlargement. These results suggest that some of the AvrBs3-induced genes may be involved in hypertrophy development and that xanthomonads possess type III effectors that steer host gene expression.

Dose-Dependent Regulation of NAD(P)H Oxidase Expression by Angiotensin II in Human Endothelial Cells: Protective Effect of Angiotensin II Type 1 Receptor Blockade in Patients With Coronary Artery Disease

Abstract: Objective— Angiotensin II (Ang II)–mediated induction of vascular superoxide anion formation could contribute to the development of endothelial dysfunction, hypertension, and atherosclerosis. An NAD(P)H oxidase has been identified as a major endothelial source of superoxide anions. However, the molecular mechanism underlying the regulation of NAD(P)H oxidase activity in response to Ang II is not well understood. Methods and Results— We investigated the dose-dependent regulation of superoxide anion formation and of NAD(P)H oxidase subunit expression in response to Ang II in human endothelial cells. Ang II regulates superoxide anion formation and the limiting subunit of endothelial NAD(P)H oxidase, gp91-phox, in a dose-dependent manner via Ang II type 1 (AT 1 ) receptor–mediated induction and Ang II type 2 receptor–mediated partial inhibition at higher Ang II concentrations. Furthermore, AT 1 receptor blocker therapy before coronary bypass surgery downregulates the gp91-phox expression in internal mammary artery biopsies of patients with coronary artery disease. Conclusions— Our data support a dose-dependent induction of proatherosclerotic oxidative stress in human endothelial cells in response to Ang II. The expression of NAD(P)H oxidase subunit gp91-phox is critical for endothelial superoxide anion formation. AT 1 receptor blockade has an antiatherosclerotic and antioxidative potential by the reduction of oxidative stress in the vessel wall.

Type II Theories Compactified on Calabi-Yau Threefolds in the Presence of Background Fluxes

Abstract: Compactifications of type II theories on Calabi-Yau threefolds including electric and magnetic background fluxes are discussed. We derive the bosonic part of the four-dimensional low energy effective action and show that it is a non-canonical N=2 supergravity which includes a massive two-form. The symplectic invariance of the theory is maintained as long as the flux parameters transform as a symplectic vector and a massive two-form which couples to both electric and magnetic field strengths is present. The mirror symmetry between type IIA and type IIB compactified on mirror manifolds is shown to hold for R-R fluxes at the level of the effective action. We also compactify type IIA in the presence of NS three-form flux but the mirror symmetry in this case remains unclear.

Developmentally regulated conversion of surface‐exposed chitin to chitosan in cell walls of plant pathogenic fungi

Abstract: Summary • Conversion of surface-exposed chitin to chitosan in cell walls of in vitro - and in vivo -differentiated infection structures of two rust fungi, the wheat stem rust fungus Puccinia graminis f. sp. tritici and the broad bean rust fungus Uromyces fabae , and of the causal agent of maize anthracnose, Colletotrichum graminicola , were studied. • Epi-fluorescence microscopy with the fluorescence-labeled lectin wheat germ agglutinin (WGA) revealed that surfaces of infection structures formed on the plant cuticle expose chitin, whereas surfaces of structures formed after invading the host do not. • To identify chitin modification by de- N -acetylation, we raised polyclonal antibodies specifically recognizing de- N -acetylated chitosan. These antibodies labeled only those infection structures that differentiate inside the plant, indicating that chitosan is exposed on cell wall surfaces post penetration. • Surface modification of the fungal cell walls by chitin de- N -acetylation is discussed as a fungal strategy to protect cell walls of pathogenic hyphae from enzymatic hydrolysis by host chitinases, and to avoid generation of an auto-catalytic defense response system in the invaded host tissue.

Comparing continuous and dichotomous scoring of the balanced inventory of desirable responding.

Abstract: The Balanced Inventory of Desirable Responding (BIDR; Paulhus, 1994) is a widely used instrument to measure the 2 components of social desirability: self-deceptive enhancement and impression management. With respect to scoring of the BIDR, Paulhus (1994) authorized 2 methods, namely continuous scoring (all answers on the continuous answer scale are counted) and dichotomous scoring (only extreme answers are counted). In this article, we report 3 studies with student samples, and continuous and dichotomous scoring of BIDR subscales are compared with respect to reliability, convergent validity, sensitivity to instructional variations, and correlations with personality. Across studies, the scores from continuous scoring (continuous scores) showed higher Cronbach's alphas than those from dichotomous scoring (dichotomous scores). Moreover, continuous scores showed higher convergent correlations with other measures of social desirability and more consistent effects with self-presentation instructions (fake-good vs. fake-bad instructions). Finally, continuous self-deceptive enhancement scores showed higher correlations with those traits of the Five-factor model for which substantial correlations were expected (i.e., Neuroticism, Extraversion, and Conscientiousness). Consequently, these findings indicate that continuous scoring may be preferable to dichotomous scoring when assessing socially desirable responding with the BIDR.

Phase I Trial Evaluating the Concurrent Combination of Radiotherapy and Capecitabine in Rectal Cancer

Abstract: PURPOSE: To establish the feasibility of concurrent radiotherapy and capecitabine and define the maximum-tolerated dose (MTD) in patients with rectal cancer. PATIENTS AND METHODS: Thirty-six patients with rectal cancer received treatment in the adjuvant, neoadjuvant, or palliative setting with a total irradiation dose of 50.4 Gy with 1.8 Gy/d in approximately 6 weeks. Capecitabine was administered at escalating doses from 250 to 1,250 mg/m2 bid (including weekends) for the duration of radiotherapy. The MTD was defined when two or more patients in a cohort of three or six patients experienced dose-limiting toxicities. RESULTS: Dose-limiting grade 3 hand-foot syndrome was observed in two of six patients treated at a capecitabine dose of 1,000 mg/m2 bid. Other toxicities were generally rare and/or mild, with only one case of non–dose-limiting grade 3 diarrhea and a single patient with grade 3 skin toxicity. Myelosuppression consisted mainly of leukocytopenia, with a maximum severity of grade 2. Thus, a dosag...