bluuebunny/crossref_metadata_2025 huggingface dataset:
Global advances in monitoring and evaluation of HIV/AIDS: From AIDS case reporting to program improvement
Authors: Rugg Deborah , Carael Michel , Ties Boerma Jan , Novak John
Published: October 2004

National programs for AIDS need the capacity to conduct their own monitoring and evaluation, not only for monitoring the epidemic and reporting to donors, but also for improving the programs.
Efforts in collaboration and coordination of HIV/AIDS monitoring and evaluation: Contributions and lessons of two U.S. government agencies in a global partnership
Authors: Rugg Deborah , Novak John , Peersman Greet , Heckert Karen A. , Spencer Jack , Marconi Katherine
Published: October 2004

In building on each agency's strengths, we must identify incentives and opportunities for collaboration, with the fundamental consensus that working together in a harmonized manner is better than going it alone.
Monitoring and evaluating the national program to prevent mother‐to‐child HIV transmission in Thailand
Authors: Kanshana Siripon , Naiwatanakul Thananda , Simonds R. J. , Amornwichet Pornsinee , Teeraratkul Achara , Culnane Mary , Chantharojwong Nartlada , Limpakarnjanarat Khanchit
Published: October 2004

In the first three years of Thailand's program, 99 percent of its public hospitals participated in the national monitoring system. Data are used to adjust national or local policies, and practices can be adjusted to improve the program.
Planning and implementing a national monitoring and evaluation system in Ghana: A participatory and decentralized approach
Authors: Anie Sylvia J. , Tettey Larbi Emmanuel
Published: October 2004

Over 2,500 organizations have been funded to carry out HIV/AIDS interventions in Ghana. A comprehensive and well‐coordinated monitoring and evaluation system‐one that is simple, strategic, and participatory‐is needed to track the national response and its effects.
A microcosm of the global challenges facing the field: Commentary on HIV/AIDS monitoring and evaluation
Authors: Patton Michael Quinn
Published: October 2004

The challenges ahead are at least as daunting as those already overcome: demonstrating that monitoring and evaluating findings can make a difference in the lives of people.
High expression of Bfl‐1 contributes to the apoptosis resistant phenotype in B‐cell chronic lymphocytic leukemia
Authors: Morales Alejo A. , Olsson Anna , Celsing Fredrik , Österborg Anders , Jondal Mikael , Osorio Lyda M.
Published: October 2004

In order to identify regulatory genes involved in the development of an apoptosis‐resistant phenotype in patients with chemotherapy refractory B‐cell chronic lymphocytic leukemia (B‐CLL) expression of apoptosis‐regulating genes in B‐CLL cells was quantified using cDNA arrays and RT‐PCR. Data were obtained from and compared between 2 groups of B‐CLL patients with either nonprogressive, indolent, previously untreated disease and with leukemic cells sensitive to in vitro fludarabine‐induced apoptosis, referred to as sensitive B‐CLL (sB‐CLL) or with progressive, chemotherapy refractory disease and with leukemic cells resistant to in vitro fludarabine‐induced apoptosis, referred to as resistant B‐CLL (rB‐CLL). By performing a supervised clustering of genes that most strongly discriminated between rB‐CLL vs. sB‐CLL a small group of genes was identified, where bfl‐1 was the strongest discriminating gene (p < 0.05), with higher expression in rB‐CLL. A group of apoptosis‐regulating genes were modulated during induction of apoptosis by serum deprivation in vitro in a similar manner in all cases studied. However, bfl‐1 was preferentially downregulated in sB‐CLL as compared to rB‐CLL (p < 0.05). We conclude that bfl‐1 may be an important regulator of B‐CLL apoptosis, which could contribute to disease progression and resistance to chemotherapy, and as such represent a future potential therapeutic target. © 2004 Wiley‐Liss, Inc.
Histone deacetylase inhibitors upregulate plakoglobin expression in bladder carcinoma cells and display antineoplastic activity in vitro and in vivo
Authors: Canes David , Chiang George J. , Billmeyer Brian R. , Austin Christina A. , Kosakowski Monika , Rieger‐Christ Kimberly M. , Libertino John A. , Summerhayes Ian C.
Published: October 2004

Histone deacetylase inhibitors (HDACis) are emerging as a promising new class of anticancer agents displaying growth‐inhibitory activity and low toxicity in vivo. In this study, we examined the effect of sodium butyrate (NaB) and trichostatin A (TSA) on the growth of human bladder carcinoma cell lines in culture and TSA on the growth of EJ and UM‐UC‐3 human bladder xenografts in nude mice. NaB and TSA suppressed the growth of bladder cell lines at millimolar (1.5–4.3 mM) and micromolar (0.03–0.33 μM) concentrations, respectively, inducing concentration‐dependent cell death. Bladder carcinoma cells within the experimental panel displayed the phenotype of late‐stage bladder lesions expressing N‐cadherin in the absence of E‐cadherin accompanied by low levels of plakoglobin expression. Exposure of these cells to HDACis resulted in upregulation of plakoglobin with no change in E‐cadherin expression. A 2‐hr exposure to TSA was the minimal time required to upregulate plakoglobin in cells with downregulation to baseline levels occurring within 24 hr following drug removal. In mice bearing EJ and UM‐UC‐3 bladder xenografts, TSA (500 μg/kg/day) caused suppression of tumor growth compared with mice receiving vehicle alone. A > 70% reduction in mean final tumor volume was recorded in both bladder xenograft models with no detectable toxicity. The results suggest that TSA inhibits bladder carcinoma cell growth and may be a useful, relatively nontoxic agent for consideration in the treatment of late‐stage bladder tumors. © 2004 Wiley‐Liss, Inc.
Genetic polymorphism of the interferon‐γ gene in cervical carcinogenesis
Authors: Lai Hung‐Cheng , Chang Cheng‐Chang , Lin Ya‐Wen , Chen Su‐Feng , Yu Mu‐Hsien , Nieh Shin , Chu Ta‐Wei , Chu Tang‐Yuan
Published: October 2004

Beyond human papillomavirus (HPV) infection, host genetic factors may contribute to cervical carcinogenesis. This study aims to test the hypothesis that CA‐dinucleotide repeat polymorphism in the first intron of the interferon‐gamma (IFN‐γ) gene is associated with HPV‐initiated cervical carcinogenesis. A hospital‐based case‐control study including patients with low‐grade squamous intraepithelial lesions (LSILs; n = 93), high‐grade squamous intraepithelial lesions (HSILs; n = 123) and invasive carcinomas (n = 153) of the uterine cervix, as well as 1:1 age‐matched controls, was conducted. The IFN‐γ genotype was determined by PCR and capillary electrophoresis with internal standards. HPV genotype was determined by consensus PCR and reverse line blot hybridization. Genotypes containing the 12 or 14 allele (12 or 14 CA repeats) were significantly more common in patients with HSILs than in controls (46% vs. 22%; OR = 3.0; 95% CI = 1.7–5.2; p < 0.0001). In contrast, genotypes containing 13 and 18 were significantly more common in controls than in patients with HSILs (76% vs. 53%; OR = 0.3; 95% CI = 0.2–0.6; p = 0.0001) or squamous cell carcinomas (74% vs. 63%; OR = 0.6; 95% CI = 0.4–1.0; p = 0.037). The frequency of the 12 and 14 genotypes increased significantly in accordance with the severity of cervical carcinogenesis (ptest for trend = 0.0002), whereas the 13 and 18 genotypes showed the opposite trend (ptest for trend = 0.007). Comparing IFN‐γ genotype and HPV status, 18‐containing genotypes were more frequently found in HPV+ LSILs, and 12‐containing genotypes were less frequently found in HPV+ HSILs. Compared with non‐13 genotypes, 13 genotype HSILs were more frequently infected with HPV58 (70% vs. 45%) and less frequently infected with HPV18 (0% vs. 16%; p= 0.007). Genetic polymorphism of the IFN‐γ gene is associated with individual susceptibility to cervical carcinogenesis. This polymorphism correlates with HPV infection in a disease‐ and type‐specific manner. © 2004 Wiley‐Liss, Inc.
Celecoxib derivatives induce apoptosis via the disruption of mitochondrial membrane potential and activation of caspase 9
Authors: Ding Haiming , Han Chunhua , Zhu Jiuxiang , Chen Ching‐Shih , D'Ambrosio Steven M.
Published: October 2004

Celecoxib is a potent nonsteroid antiinflammatory drug (NSAID) that has shown great promise in cancer chemoprevention and treatment. The tumor suppression activity of celecoxib and other NSAIDs have been related to the induction of apoptosis in many cancer cell lines and animal models. While celecoxib is a specific inhibitor of cyclooxygenase (COX)‐2, recent data indicate that its apoptotic properties may also be mediated through COX‐independent pathways. In our study, we evaluated second generation celecoxib derivatives, lacking COX‐2 inhibitory activity, in a premalignant and malignant human oral cell culture model to determine their potential anticancer effect and mechanisms responsible for the COX‐independent apoptotic activity. Celecoxib and its derivatives delayed the progression of cells through the G2/M phase and induced apoptosis. The derivatives with apolar substituents at the terminal phenyl moiety of celecoxib greatly enhanced apoptosis and cell cycle delay. Apoptosis and cell cycle arrest appeared to be independent of derivative induced inhibition of PDK1 and phosphorylation of Akt and Erk1/2. Derivatives induced apoptosis was mediated by the cleavage and activation of caspase‐9 and caspase‐3, but not caspase 8, implicating the mitochondrial pathway for apoptosis induction. Inhibitors of caspase‐3 and caspase‐9 and cyclosporin A, a mitochondrial membrane potential stabilizer, attenuated derivative induced apoptosis. Inhibition of caspase‐3 prevented the activation of caspase 8, while the inhibition of caspase‐9 inhibitor blocked activation of both caspase 3 and 8 by the derivatives. Apoptosis was independent of Bcl‐2. These results indicate that the second generation celecoxib derivatives induce apoptosis in human oral cancer lines by the disruption of mitochondrial membrane potential activating caspase 9 and downstream caspase 3 and 8. This suggests that the modification of the celecoxib structure can lead to highly effective COX‐independent growth inhibitory and apoptotic agents in chemoprevention and therapy. © 2004 Wiley‐Liss, Inc.
Plasma folate, vitamin B12, and homocysteine and prostate cancer risk: A prospective study
Authors: Hultdin Johan , Van Guelpen Bethany , Bergh Anders , Hallmans Göran , Stattin Pär
Published: October 2004

The role of folate metabolism in cancer development is a topic of much current interest, with maintenance of adequate folate status tending to show a protective effect. Aberrant methylation, primarily hypermethylation of certain genes including tumor suppressors, has been implicated in prostate cancer development. Folate, vitamin B12 and homocysteine are essential for methyl group metabolism and thus also for DNA methylation. We related plasma levels of these factors to prostate cancer risk in a prospective study of 254 case subjects and 514 matched control subjects. Increasing plasma levels of folate and vitamin B12 were statistically significantly associated with increased prostate cancer risk, with an odds ratio of 1.60 (95% CI = 1.03–2.49; ptrend = 0.02) for folate and 2.63 (95% CI = 1.61–4.29; ptrend < 0.001) for vitamin B12 for highest vs. lowest quartile. Increasing plasma homocysteine levels were associated with a reduced risk of borderline significance (OR = 0.67; 95% CI = 0.43–1.04; ptrend = 0.08). After adjustment for the other 2 plasma variables, body mass index and smoking, a statistically significant increased risk remained only for vitamin B12 (OR = 2.96; 95% CI = 1.58–5.55; ptrend = 0.001). Adjusted OR for folate and homocysteine were 1.30 (95% CI = 0.74–2.24; ptrend = 0.17) and 0.91 (95% CI = 0.51–1.58; ptrend = 0.60), respectively. Our results suggest that factors contributing to folate status are not protective against prostate cancer. On the contrary, vitamin B12, associated with an up to 3‐fold increase in risk, and possibly also folate, may even stimulate prostate cancer development. These findings are novel and should be explored further in future studies. © 2004 Wiley‐Liss, Inc.
Influence of GSTM1, GSTT1, GSTP1 and NAT2 genotypes on the p53 mutational spectrum in bladder tumours
Authors: Ryk Charlotta , Berggren Petra , Kumar Rajiv , Hemminki Kari , Larsson Per , Steineck Gunnar , Lambert Bo , Hou Sai‐Mei
Published: October 2004

Genetic polymorphisms affecting expression or activity of the corresponding enzymes can influence the risk of acquiring gene mutations and various cancers. We have studied 327 bladder cancer patients with regard to the functionally related polymorphisms of GSTM1, GSTT1, GSTP1 and NAT2 and analysed the p53 mutational status of their tumours. Fifty p53 mutations, 26% transversions and 74% transitions, were detected in 44 patients. P53 mutation frequency was significantly higher in higher‐grade tumours than in low‐grade tumours (OR = 2.09, 95% CI 1.44–3.02, adjusted for age and sex). Also, a significant association was found between tumour stage (Tis and T2+ vs. Ta and T1) and presence of the GSTP1 val allele (adjusted OR = 2.00, CI 1.14–3.52). Overall, there was no significant difference in frequency of p53 mutation among patients with different genotypes. Among patients with p53 mutation, transversions were significantly more frequent in GSTM1‐negative as compared to GSTM1‐positive individuals (OR = 5.18, CI 1.07–25.02, adjusted for age, sex and tumour stage). With one exception, all tumours with the most common type of transversion, G:C‐C:G, occurred in GSTM1‐negative patients. Among smokers, all transversions (3 of 3), but only 2 of 13 transitions, were found among carriers of the GSTP1 variant allele, and samples carrying at least 1 variant GSTP1 allele had more transitions at CpG sites than wild‐type samples (adjusted OR = 4.61, CI 0.82–26.04). No significant associations were found for the NAT2 gene. Our results suggest that impaired glutathione conjugation may affect the mutation spectrum in critical target genes. © 2004 Wiley‐Liss, Inc.
Detection of epithelial ovarian cancer using 1H‐NMR‐based metabonomics
Authors: Odunsi Kunle , Wollman Robert M. , Ambrosone Christine B. , Hutson Alan , McCann Susan E. , Tammela Jonathan , Geisler John P. , Miller Gregory , Sellers Thomas , Cliby William , Qian Feng , Keitz Bernadette , Intengan Marilyn , Lele Shashikant , Alderfer James L.
Published: October 2004

Currently available serum biomarkers are insufficiently reliable to distinguish patients with epithelial ovarian cancer (EOC) from healthy individuals. Metabonomics, the study of metabolic processes in biologic systems, is based on the use of 1H‐NMR spectroscopy and multivariate statistics for biochemical data generation and interpretation and may provide a characteristic fingerprint in disease. In an effort to examine the utility of the metabonomic approach for discriminating sera from women with EOC from healthy controls, we performed 1H‐NMR spectroscopic analysis on preoperative serum specimens obtained from 38 patients with EOC, 12 patients with benign ovarian cysts and 53 healthy women. After data reduction, we applied both unsupervised Principal Component Analysis (PCA) and supervised Soft Independent Modeling of Class Analogy (SIMCA) for pattern recognition. The sensitivity and specificity tradeoffs were summarized for each variable using the area under the receiver‐operating characteristic (ROC) curve. In addition, we analyzed the regions of NMR spectra that most strongly influence separation of sera of EOC patients from healthy controls. PCA analysis allowed correct separation of all serum specimens from 38 patients with EOC (100%) from all of the 21 premenopausal normal samples (100%) and from all the sera from patients with benign ovarian disease (100%). In addition, it was possible to correctly separate 37 of 38 (97.4%) cancer specimens from 31 of 32 (97%) postmenopausal control sera. SIMCA analysis using the Cooman's plot demonstrated that sera classes from patients with EOC, benign ovarian cysts and the postmenopausal healthy controls did not share multivariate space, providing validation for the class separation. ROC analysis indicated that the sera from patients with and without disease could be identified with 100% sensitivity and specificity at the 1H‐NMR regions 2.77 parts per million (ppm) and 2.04 ppm from the origin (AUC of ROC curve = 1.0). In addition, the regression coefficients most influential for the EOC samples compared to postmenopausal controls lie around δ3.7 ppm (due mainly to sugar hydrogens). Other loadings most influential for the EOC samples lie around δ2.25 ppm and δ1.18 ppm. These findings indicate that 1H‐NMR metabonomic analysis of serum achieves complete separation of EOC patients from healthy controls. The metabonomic approach deserves further evaluation as a potential novel strategy for the early detection of epithelial ovarian cancer. © 2004 Wiley‐Liss, Inc.
In vivo efficacy of STI571 in xenografted human small cell lung cancer alone or combined with chemotherapy
Authors: Decaudin Didier , de Cremoux Patricia , Sastre Xavier , Judde Jean‐Gabriel , Nemati Fariba , Tran‐Perennou Carine , Fréneaux Paul , Livartowski Alain , Pouillart Pierre , Poupon Marie‐France
Published: October 2004

STI571, or imatinib, selectively inhibits BCR/ABL, PDGFR and c‐kit kinase activity. It has been reported that a large proportion of small cell lung cancer (SCLC) cell lines and tumors express c‐kit and that STI571 inhibits tumor cell growth. We therefore investigated the therapeutic efficacy of STI571, alone or combined with chemotherapy, in human SCLC cells or tumors xenografted into nude mice. The level of c‐kit mRNA expression was variable in SCLC tumors (positive for 2 of 4 xenografts), and c‐kit protein was not detected by immunohistochemistry. On the 4 xenografted tumors, PDGFRα and PDGFRβ were not detected by immunohistochemistry. STI571 induced inhibition of proliferation of the SCLC6 cell line without inducing apoptosis; in contrast, in combination with etoposide or topotecan, the growth inhibition of SCLC6 cells induced by STI571 was increased, with apoptotic DNA fragmentation. Four human SCLC xenografts (SCLC6, SCLC61, SCLC74 and SCLC108) were transplanted into mice. After intraperitoneal injection of STI571, we observed 80%, 40% and 78% growth inhibition of SCLC6, SCLC61 and SCLC108 tumors, respectively, without any significant inhibition of SCLC74 tumor growth. In mice bearing responsive SCLC tumors, we observed an increase of growth inhibition induced by chemotherapy (etoposide + ifosfamide or topotecan) by concomitant and continuous administration of STI571, associated with an increase of toxic deaths. In SCLC6‐bearing mice receiving sequential treatments, we observed a reduction of toxic deaths but a decrease of synergistic antitumor efficacy. In conclusion, the efficacy of STI571 alone in SCLC xenografted tumors was variable and did not depend on c‐kit expression. Moreover, a significant increase of chemotherapy‐induced growth inhibition was obtained by concomitant administration of STI571 that should be carefully investigated in SCLC patients. © 2004 Wiley‐Liss, Inc.
Microvesicles derived from activated platelets induce metastasis and angiogenesis in lung cancer
Authors: Janowska‐Wieczorek Anna , Wysoczynski Marcin , Kijowski Jacek , Marquez‐Curtis Leah , Machalinski Bogdan , Ratajczak Janina , Ratajczak Mariusz Z.
Published: October 2004

The role of platelets in tumor progression and metastasis has been recognized but the mechanism of their action remains unclear. Five human lung cancer cell lines (A549, CRL 2066, CRL 2062, HTB 183, HTB 177) and a murine Lewis lung carcinoma (LCC) cell line (for an in vivo model of metastasis) were used to investigate how platelet‐derived microvesicles (PMV), which are circular fragments shed from the surface membranes of activated platelets, and exosomes released from platelet α‐granules, could contribute to metastatic spread. We found that PMV transferred the platelet‐derived integrin CD41 to most of the lung cancer cell lines tested and stimulated the phosphorylation of mitogen‐activated protein kinase p42/44 and serine/threonine kinase as well as the expression of membrane type 1‐matrix metalloproteinase (MT1‐MMP). PMV chemoattracted 4 of the 5 cell lines, with the highly metastatic A549 cells exhibiting the strongest response. In A549 cells, PMV were shown to stimulate proliferation, upregulate cyclin D2 expression and increase trans‐Matrigel chemoinvasion. Furthermore, in these cells, PMV stimulated mRNA expression for angiogenic factors such as MMP‐9, vascular endothelial growth factor, interleukin‐8 and hepatocyte growth factor, as well as adhesion to fibrinogen and human umbilical vein endothelial cells. Intravenous injection of murine PMV‐covered LLC cells into syngeneic mice resulted in significantly more metastatic foci in their lungs and LLC cells in bone marrow than in control animals injected with LCC cells not covered with PMV. Based on these findings, we suggest that PMV play an important role in tumor progression/metastasis and angiogenesis in lung cancer. © 2004 Wiley‐Liss, Inc.
Immunohistological evaluation of single small hepatocellular carcinoma with negative staining of monoclonal antibody Hepatocyte Paraffin 1
Authors: Sugiki Takaaki , Yamamoto Masakazu , Aruga Atsushi , Takasaki Ken , Nakano Masayuki
Published: October 2004

Background and Objectives

The sensitivity and specificity of the monoclonal antibody Hepatocyte Paraffin 1 (Hep Par 1) for hepatocellular carcinoma (HCC) are very high, and the usefulness for differential diagnosis of hepatic tumors has been reported. However, there are some cases of HCC with negative staining for Hep Par 1. We examined the histopathological features of HCC with negative staining for Hep Par 1.

Methods

We examined 69 samples of single nodular HCC less than 2 cm in greatest dimension, resected from 1985 to 1994 in our hospital, with immunohistological staining for Hep Par 1, cytokeratin 19 (CK 19), MUC‐1 glycoprotein (MUC‐1), and epithelial membrane antigen (EMA).

Results

Hep Par 1 staining was positive in 64 cases (93%) and negative in 5 cases (7%). With regard to the histological structure, 3 of the 5 negative cases were scirrhous HCC. With regard to the grade of histological differentiation, 2 cases were poorly differentiated HCC, 3 cases were moderately differentiated HCC, and no well‐differentiated HCC was found in the negative cases. CK 19, MUC‐1, and EMA staining were negative in all cases.

Conclusions

It is necessary to recognize the existence of Hep Par 1 negative HCC, in particular scirrhous HCC. This may be due to a different mechanism in the earlier stage of hepatocarcinogenesis. J. Surg. Oncol. 2004;88:104–107. © 2004 Wiley‐Liss, Inc.
Einfluss der Rauheit auf die mikrotribologischen Eigenschaften von unterschiedlich strukturierten Siliziumoberflächen bedeckt mit selbstorganisierten Monoschichten
Authors: Hild W. , Hungenbach G. , Schaefer J. A. , Fischer M. , Ahmed S. I.‐U. , Scherge M.
Published: October 2004

Erscheinungen, wie Reibung, Adhäsion und Benetzbarkeit sich bewegender Teile haben einen großen Einfluss auf die Lebensdauer und mechanischen Eigenschaften von Mikrosystemen. Es ist bekannt, dass Wasser einen negativen Einfluss auf die Lebensdauer hat und zum Verkleben von Bauteilen (Adhäsion) sowie zu hoher Reibung und Verschleiß führt. Hydrophobe selbstorganisierte Monoschichten (SAMs) eliminieren den Einfluss des Wassers und verringern Adhäsion und Reibung. Einen ähnlichen Effekt hat eine Zunahme der Rauheit und die damit verbundene Verringerung der realen Kontaktfläche. Durch Plasma‐Ätzen wurde durch Wahl der Ätzparameter (Leistung, Zeit, Gasfluss, Druck usw.) die Rauheit modifiziert. Es werden die mikrotribologischen Eigenschaften als Funktion der Oberflächentopographie und der Last von natürlichem Oxid auf Si(100) (einer Wasser‐anziehenden Probe) und Si(100) bedeckt mit Octadecyltrichlorsilan (OTS) und Perfluorodecyltrichlorsilan (FDTS) untersucht. Die Reibungs‐Last‐Kurve auf der polierten Oxid‐bedeckten Probe genügt, in Verbindung mit dem Bowden‐Tabor‐Modell, dem Johnson‐Kendall‐Roberts‐Modell und auf den OTS‐bedeckten Proben dem Hertz‐Modell. Für die FDTS‐bedeckten Proben steigt sie linear an. Mit steigender Rauheit sinkt die Reibung für die Oxid‐ und FDTS‐bedeckten Proben. Im Gegensatz dazu erhöht sie sich für OTS und wird linear. Lebensdaueruntersuchungen der Monoschichten in Abhängigkeit von der Last deuten an, dass bei hohen Rauheiten eine geringere Lebensdauer auftritt als bei niedrigen. Außerdem wird der Verschleißmechanismus der Monolagen diskutiert.
Prognose des Abrasivverschleisses bei Bauteilen aus Grobblech mit Methoden der Statistischen Versuchsplanung
Authors: Bauer D. , Pickhan U. , Schröder X.
Published: October 2004

Der PIN ABRASION TEST ist ein international anerkannter Versuch zur Messung des Abrasivverschleisses unter Laborbedingungen. Es wird gezeigt, wie mit Hilfe dieses Tests eine Prognose des zu erwartenden Abrasivverschleisses von Bauteilen aus Grobblechen, die aus unterschiedlichen Stahlwerkstoffen bestehen können, möglich ist. Zu diesem Zweck kommt eine spezielle Methode der statistischen Mathematik bei der Planung und Ausführung der Experimente zur Anwendung. Dabei werden sogenannte vollständige 2n‐Pläne nach R. A. Fisher verwendet. Diese berücksichtigen den Einfluss von n=5 Faktoren: Normalkraft, Gleitgeschwindigkeit, Größe, Härte der Abrasivteilchen und Härte der Grobblechwerkstoffe. Die Auswertung der Versuchsergebnisse erfolgt mittels Regressionsanalyse. Es lässt sich eine multilineare mathematische Funktion definieren. Diese Funktion berücksichtigt sämtliche signifikanten Effekte und Wechselwirkungen der Einflussfaktoren und erlaubt eine Prognose des Abrasivverschleisses. Damit lassen sich die Ergebnisse der Laborversuche erfolgreich in die industrielle Praxis übertragen.
Verschleißmechanismen bei moderater und extremer Grenzreibung
Authors: Scherge M. , Pöhlmann K.
Published: October 2004

Mit einem Stift‐Scheibe‐Tribometer wurden für das System Stahlstift/Stahlscheibe Versuche durchgeführt, die drastisch unterschiedliche Verschleißraten zur Folge hatten. Durch Wahl der Normalkraft wurde die Energiedissipation so eingestellt, dass im ersten Versuch Verschleißraten in der Größenordnung von Nanometern pro Stunde erreicht wurden, während im zweiten Versuch Mikrometer pro Stunde erzielt wurden. Die Proben wurden nach dem Experiment hinsichtlich Struktur und chemischer Zusammensetzung analysiert. Im Bereich der kleinen Verschleißraten dominierten plastisches Fließen und mechanische Vermischung während die hohen Verschleißraten mit starker Topographieänderung und Oxidation einher gingen.
Friction and Wear of Carbon Fibre Filled Polymer Composites at Room and Low Temperatures
Authors: Theiler G. , Hübner W. , Gradt Th. , Klein P.
Published: October 2004

In the cryogenic temperature range common lubricants solidify and therefore, they cannot be applied. Thus, for tribosystems in low temperature environment technical solutions based on good dry lubricating properties of the materials themselves must be found. In this concern polymers are of great interest, because they show comparatively high mechanical strength at low density, and they often possess favourable friction and wear properties at low temperatures.

This work presents investigations on the tribological behaviour of carbon fibre (CF) filled PTFE and PEEK composites in a cryogenic environment (liquid nitrogen; T = −196 °C). In general, these materials clearly exhibit lower friction and wear properties at low temperatures than at room temperature, which can be explained mainly by the temperature dependence of the mechanical strength. With increasing amount of carbon fibres in both composites, friction and wear increase. The optimal composition was found to be at 5 wt.% CF for the friction and 15 wt.% CF for the wear values. At low temperatures, the percentage of carbon fibres in PTFE and PEEK composites has not such an important influence as it has at room temperature.
Anisotropic elastic–plastic analysis of shells at large strains. A comparison of multiplicative and additive approaches to enhanced finite element design and constitutive modelling
Authors: Miehe Christian , Apel Nikolas
Published: October 2004

The article presents new aspects of large‐strain anisotropic elastoplastic analyses of shells. On the side of computational shell analysis we focus on recently developed brick‐type mixed finite shell elements based on trilinear displacement interpolations equipped with enhanced strain modes and shell‐typical assumed strain modifications. Here, we compare two classes of this shell element design based on a multiplicative and an additive definition of an enhanced strain measure, respectively. Furthermore, for both types of continuum‐based shell elements we outline unified interfaces to strain‐driven constitutive stress update algorithms of anisotropic finite plasticity. On the side of computational plasticity we investigate two classes of constitutive models suitable for the description of anisotropic elastoplastic response at finite strains. The first framework uses a multiplicative definition of an elastic strain measure based on a plastic map, the second an additively defined elastic strain measure based on a plastic metric. Both constitutive frameworks use Hencky‐type logarithmic strain measures and are specified to a model problem of orthotropic elastic–plastic response of a standard material. The algorithmic treatment of the two constitutive models is based on an incremental variational formulation that defines the stresses and consistent tangent moduli in terms of a function evaluation. We compare the performances of the two finite element formulations and the two constitutive models by means of numerical simulations of sheet drawing processes. For the range of metal plasticity at moderate strains it is shown that results obtained with the different approaches are close to each other, while the additive approaches provide simpler and more efficient settings. Copyright © 2004 John Wiley & Sons, Ltd.
3,6‐linked 9‐alkyl‐9H‐carbazole main‐chain polymers: Preparation and properties
Authors: Iraqi Ahmed , Wataru Isao
Published: October 2004

An investigation into the preparation of poly(9‐alkyl‐9H‐carbazole‐3,6‐diyl)s with palladium catalyzed cross‐coupling reactions of 3‐halo‐6‐halomagnesio‐9‐alkyl‐9H‐carbazoles, generated in situ from their corresponding 3,6‐diiodo‐ and 3,6‐dibromo‐derivatives was undertaken. Monomers with a range of alkyl group substituents with different steric requirements were investigated and their effects on the polymerization were studied. The effects of the nature of halogen substituents on the polymerization reaction were also investigated. Structural analysis of the polymers revealed exclusive 3,6‐linkage between consecutive carbazole repeat units on the polymer chains. The physical properties of these polymers were investigated with spectroscopic, thermal gravimetric analysis, and electrochemical studies. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6041–6051, 2004
Analysis of singleton ORFans in fully sequenced microbial genomes
Authors: Siew Naomi , Fischer Daniel
Published: October 2004

Singleton sequence ORFans are orphan ORFs (open reading frames) that have no detectable sequence similarity to any other sequence in the databases. ORFans are of particular interest not only as evolutionary puzzles but also because we can learn little about them using bioinformatics tools. Here, we present a first systematic analysis of singleton ORFans in the first 60 fully sequenced microbial genomes. We show that although ORFans have been underemphasized, the number of ORFans is steadily growing, currently accounting for 23,634 sequences. At the same time, the percentage of ORFans as a fraction of all sequences is slowly diminishing, and is currently about 14%. Short ORFans comprise about 61% of all ORFans. The abundance of short ORFans may be due to a yet unexplained artifact. The data also suggest that the number of longer ORFans may soon diminish as more genomes of closely related organisms become available. To better address the questions about the functions and origins of ORFans, we propose to focus further studies on the longer ORFans, with emphasis on three new types of ORFans: ORFan modules, paralogous ORFans, and orthologous ORFans. We conclude that the large number of ORFans reflects an intrinsic property of the genetic material not yet fully understood. Further computational and experimental studies aimed at understanding Nature's protein diversity should also include ORFans. Proteins 2003. © 2003 Wiley‐Liss, Inc.
Molecular dynamics simulations of galectin‐1‐oligosaccharide complexes reveal the molecular basis for ligand diversity
Authors: Ford Michael G. , Weimar Thomas , Köhli Thies , Woods Robert J.
Published: October 2004

Galectin‐1 is a member of a protein family historically characterized by its ability to bind carbohydrates containing a terminal galactosyl residue. Galectin‐1 is found in a variety of mammalian tissues as a homodimer of 14.5‐kDa subunits. A number of developmental and regulatory processes have been attributed to the ability of galectin‐1 to bind a variety of oligosaccharides containing the Gal‐β‐(1,4)‐GlcNAc (LacNAcII) sequence. To probe the origin of this permissive binding, solvated molecular dynamics (MD) simulations of several representative galectin‐1‐ligand complexes have been performed. Simulations of structurally defined complexes have validated the computational approach and expanded upon data obtained from X‐ray crystallography and surface plasmon resonance measurements. The MD results indicate that a set of anchoring interactions between the galectin‐1 carbohydrate recognition domain (CRD) and the LacNAc core are maintained for a diverse set of ligands and that substituents at the nonreducing terminus of the oligosaccharide extend into the remainder of a characteristic surface groove. The anionic nature of ligands exhibiting relatively high affinities for galectin‐1 implicates electrostatic interactions in ligand selectivity, which is confirmed by a generalized Born analysis of the complexes. The results suggest that the search for a single endogenous ligand or function for this lectin may be inappropriate and instead support a more general role for galectin‐1, in which the lectin is able to crosslink heterogeneous oligosaccharides displayed on a variety of cell surfaces. Such binding promiscuity provides an explanation for the variety of adhesion phenomena mediated by galectin‐1. Proteins 2003. © 2003 Wiley‐Liss, Inc.
Free energy landscape of protein folding in water: Explicit vs. implicit solvent
Authors: Zhou Ruhong
Published: October 2004

The Generalized Born (GB) continuum solvent model is arguably the most widely used implicit solvent model in protein folding and protein structure prediction simulations; however, it still remains an open question on how well the model behaves in these large‐scale simulations. The current study uses the β‐hairpin from C‐terminus of protein G as an example to explore the folding free energy landscape with various GB models, and the results are compared to the explicit solvent simulations and experiments. All free energy landscapes are obtained from extensive conformation space sampling with a highly parallel replica exchange method. Because solvation model parameters are strongly coupled with force fields, five different force field/solvation model combinations are examined and compared in this study, namely the explicit solvent model: OPLSAA/SPC model, and the implicit solvent models: OPLSAA/SGB (Surface GB), AMBER94/GBSA (GB with Solvent Accessible Surface Area), AMBER96/GBSA, and AMBER99/GBSA. Surprisingly, we find that the free energy landscapes from implicit solvent models are quite different from that of the explicit solvent model. Except for AMBER96/GBSA, all other implicit solvent models find the lowest free energy state not the native state. All implicit solvent models show erroneous salt‐bridge effects between charged residues, particularly in OPLSAA/SGB model, where the overly strong salt‐bridge effect results in an overweighting of a non‐native structure with one hydrophobic residue F52 expelled from the hydrophobic core in order to make better salt bridges. On the other hand, both AMBER94/GBSA and AMBER99/GBSA models turn the β‐hairpin in to an α‐helix, and the α‐helical content is much higher than the previously reported α‐helices in an explicit solvent simulation with AMBER94 (AMBER94/TIP3P). Only AMBER96/GBSA shows a reasonable free energy landscape with the lowest free energy structure the native one despite an erroneous salt‐bridge between D47 and K50. Detailed results on free energy contour maps, lowest free energy structures, distribution of native contacts, α‐helical content during the folding process, NOE comparison with NMR, and temperature dependences are reported and discussed for all five models. Proteins 2003. © 2003 Wiley‐Liss, Inc.
Crystal structures of ferrous horse heart myoglobin complexed with nitric oxide and nitrosoethane
Authors: Copeland Daniel M. , West Ann H. , Richter‐Addo George B.
Published: October 2004

The interactions of nitric oxide (NO) and organic nitroso compounds with heme proteins are biologically important, and adduct formation between NO‐containing compounds and myoglobin (Mb) have served as prototypical systems for studies of these interactions. We have prepared crystals of horse heart (hh) MbNO from nitrosylation of aqua‐metMb crystals, and we have determined the crystal structure of hh MbNO at a resolution of 1.9 Å. The Fe‐N‐O angle of 147° in hh MbNO is larger than the corresponding 112° angle previously determined from the crystal structure of sperm whale MbNO (Brucker et al., Proteins 1998;30:352–356) but is similar to the 150° angle determined from a MS XAFS study of a frozen solution of hh MbNO (Rich et al., J Am Chem Soc 1998;120:10827–10836). The Fe‐N(O) bond length of 2.0 Å (this work) is longer than the 1.75 Å distance determined from the XAFS study and suggests distal pocket influences on FeNO geometry. The nitrosyl N atom is located 3.0 Å from the imidazole Nϵ atom of the distal His64 residue, suggesting electrostatic stabilization of the FeNO moiety by His64. The crystal structure of the nitrosoethane adduct of ferrous hh Mb was determined at a resolution of 1.7 Å. The nitroso O atom of the EtNO ligand is located 2.7 Å from the imidazole Nϵ atom of His64, suggesting a hydrogen bond interaction between these groups. To the best of our knowledge, the crystal structure of hh Mb(EtNO) is the first such determination of a nitrosoalkane adduct of a heme protein. Proteins 2003. © 2003 Wiley‐Liss, Inc.
3D structural model of the G‐protein‐coupled cannabinoid CB2 receptor
Authors: Xie Xiang‐Qun , Chen Jian‐Zhong , Billings Eric M.
Published: October 2004

The potential for therapeutic specificity in regulating diseases and for reduced side effects has made cannabinoid (CB) receptors one of the most important G‐protein‐coupled receptor (GPCR) targets for drug discovery. The cannabinoid (CB) receptor subtype CB2 is of particular interest due to its involvement in signal transduction in the immune system and its increased characterization by mutational and other studies. However, our understanding of their mode of action has been limited by the absence of an experimental receptor structure. In this study, we have developed a 3D model of the CB2 receptor based on the recent crystal structure of a related GPCR, bovine rhodopsin. The model was developed using multiple sequence alignment of homologous receptor sub‐types in humans and mammals, and compared with other GPCRs. Alignments were analyzed with mutation scores, pairwise hydrophobicity profiles and Kyte‐Doolittle plots. The 3D model of the transmembrane segment was generated by mapping the CB2 sequence onto the homologous residues of the rhodopsin structure. The extra‐ and intracellular loop regions of the CB2 were generated by searching for homologous Cα backbone sequences in published structures in the Brookhaven Protein Databank (PDB). Residue side chains were positioned through a combination of rotamer library searches, simulated annealing and minimization. Intermediate models of the 7TM helix bundles were analyzed in terms of helix tilt angles, hydrogen‐bond networks, conserved residues and motifs, possible disulfide bonds. The amphipathic cytoplasmic helix domain was also correlated with biological and site‐directed mutagenesis data. Finally, the model receptor‐binding cavity was characterized using solvent‐accessible surface approach. Proteins 2003. © 2003 Wiley‐Liss, Inc.
Pentalanthanum ethenide(4‐) digermanide(4‐), La5(C2)Ge2
Authors: Carrillo–Cabrera Wilder , Čurda Jan , Peters Karl , Kohout Miroslav , von Schnering Hans Georg
Published: October 2004

La5(C2)Ge2 was obtained as a minor component from the reaction of the elements in corundum crucibles enclosed in stainless steel ampoules at 1360 K. The compound is gray with metallic luster. The crystal structure of La5(C2)Ge2 (space group Pbam, a = 8.873Å, b = 12.946Å, c = 4.273Å; Z = 2; Rgt(F) = 0.069, Rw(F2) = 0.147) is an arrangement of condensed La9 3‐fold capped trigonal prisms and La6 octahedra, centered by Ge atoms and C2 dumbbells, respectively (d(Ge‐La) = 3.173 ‐ 3.887Å; d(C‐La) = 2.42Å (end‐on) and 2.83Å (side‐on); d(C‐C) = 1.34Å). The structure differs from the La2SnS5 structure with covalent S—S bonds only by the replacement of the Sn atoms by C2 dumbbells: La2SnS5 = S5(Sn)La2 ≙ La5(C2)Ge2. The anionic chains of edge‐condensed octahedra [SnS4/2S2]4‐ are replaced by [(C2)La4/2La2] chains, containing remarkable piles of alternating C2 and La2 pairs (d(La‐La) = 3.438Å) with side‐on coordination along the c axis. The formal oxidation states La3+, Ge4‐, C24‐ yield in an excess of three electrons per formula unit. The source of rest electron density of about 2.5 e·Å‐3 is analyzed and discussed. The calculated band structure indicates metallic behavior.
LixH12‐x‐y+z[P12OyN24‐y]Xz(X = Cl, Br) ‐ Oxonitridophosphate mit NPO‐Zeolithstruktur
Authors: Correll Sascha , Stock Norbert , Oeckler Oliver , Senker Jürgen , Nilges Tom , Schnick Wolfgang
Published: October 2004

Die Oxonitridophosphate LixH12‐x‐y+z[P12OyN24‐y]Clz(1a) und LixH12‐x‐y+z[P12OyN24‐y]Brz(1b) wurden durch Reaktion von Li2S, SP(NH2)3, OP(NH2)3und NH4Cl bzw. NH4Br in geschlossenen Ampullen bei 700 °C im Röhrenofen erhalten. Die Kristallstruktur von LixH12‐x‐y+z[P12OyN24‐y]Xz(X = Cl, Br) (1) wurde an Einkristallen von1aund Mischkristallen1abmittels Röntgenbeugung (Pna21;a= 475.3(1) pm,b= 1420.8(3) pm,c= 820.3(2) pm (1a) bzw.a= 476.6(1) pm,b= 1426.3(3) pm,c= 823.5(2) pm (1ab); Z = 1) und an Pulverproben von1amittels Röntgenbeugung, Neutronenbeugung, Elektronenbeugung und Festkörper‐NMR‐Spektroskopie aufgeklärt. Das anionische Netzwerk ist aus allseitig eckenverknüpften P(O, N)4Tetraedern unter Ausbildung von Zwölferring‐Kanälen aufgebaut. Die Lithium‐ und Halogenid‐Ionen befinden sich in diesen Kanälen. Die chemische Zusammensetzung der Proben wurde über EDX‐ und Elementaranalysen bestimmt. IR‐ und Raman‐spektroskopische Eigenschaften sowie das thermische Verhalten wurden untersucht. Impedanzspektroskopische Messungen zeigten eine Lithium‐Ionen‐Leitfähigkeit.
Phosphate‐inhibition of lipase activity in peanuts
Authors: Jacks T. J. , Yatsu L. Y.
Published: October 2004

Competitive inhibition of lipase activity in extracts of germinating peanuts occurred in media containing inorganic phosphate in concentrations above 10 mM. Lipase activity in germinating castor, cotton, and pumkin seeds and in quiescent castor seed was not similarly affected. Applications of this finding to peanut processing are suggested.
Dysmorphic Villi Mimicking Partial Mole in a Case with del(18)(q21)
Authors: Rakheja Dinesh , Wilson Kathleen S. , Rogers Beverly B.
Published: October 2004

In this article, we report the histopathologic findings in a placenta from an early second trimester abortion. The placental villi showed prominent scalloping with many intravillous trophoblastic pseudoinclusions and mild trophoblastic hyperplasia, mimicking the morphology of partial hydatidiform mole. The placental karyotype was 46,XY,del(18)(q21). These histopathologic changes have been previously described in numerical chromosomal aberrations like triploidy, tetraploidy, and trisomies, but not in structural chromosomal abnormalities.
Geometrical control of scintillation indices: What happens for GPS satellites
Authors: Forte B. , Radicella S. M.
Published: October 2004

Geometrical control of the effective outer scale imposed by detrend filtering, in the presence of highly anisotropic irregularities, explains differences between scintillation indices ratio at different locations. On the basis of weak scatter theory results, the behavior of the geometrical factor G, responsible for static effect of diffraction, is investigated in the case of GPS satellites. A simple comparison is made between GPS satellites and polar orbiting satellites used in the past for scintillation experiments to understand such differences in the behavior of scintillation indices measured by means of GPS scintillation monitors.
Scandinavian storminess since about 1800
Authors: Bärring Lars , von Storch Hans
Published: October 2004

We study the history of storminess in Northern Europe, as derived from local pressure observations in Lund since 1780 and Stockholm since 1820 (Sweden). At both stations barometer readings were made three times per day, morning, midday and evening, and after about 1850 at fixed observation hours. We use four common storminess indices: annual number of deep lows (p < 980 hPa), the annual 95th and 99th percentile of pressure changes between two observations, and the annual number of fast absolute pressure changes (∣Δp∣/Δt > 16 hPa/12 h). It turns out that the 1980's–mid 1990's were a period of enhanced storminess, mainly seen in the Stockholm record, but his period is within the natural variability of the records. Thus, there are no robust signs of any long‐term trend in the storminess indices. Storminess is during the entire historical period remarkably stable, with no systematic change and little transient variability.
Surface wave dispersion from small vertical scatterers
Authors: van Wijk K. , Levshin A. L.
Published: October 2004

Heterogeneity in the subsurface creates conflicting types of dispersion of seismic waves. A laboratory and numerical experiment show that multiple scattering of elastic waves from isolated heterogeneities near the surface not only attenuates, but also delays coherent events. Because scattering off these impedance contrasts is frequency dependent, multiple scattering is a source of dispersion. If ignored, multiple scattering dispersion could be erroneously attributed to a model with horizontal homogeneous layers of different wave speeds.
Diurnal and seasonal variability of the meteoric flux at the South Pole measured with radars
Authors: Janches D. , Palo S. E. , Lau E. M. , Avery S. K. , Avery J. P. , de la Peña S. , Makarov N. A.
Published: October 2004

A meteor radar system was installed at the South Pole in 2001 to measure the horizontal wind field in the MLT region. It uses four 6‐element yagi antennas pointing in orthogonal directions for transmission. For reception two independent systems are used: the same yagi antennas used for transmission (COBRA data acquisition system) and an interferometric array of five crossed‐dipole antennas (MEDAC data acquisition system). In this paper we present and discuss VHF radio meteor observations from the South Pole. Preliminary results showing the diurnal and seasonal variability of the meteor flux indicate that most of the activity occurs during the Antarctic summer around a very concentrated region of the sky in elevation and azimuth. These results agree well with meteor observations performed at Arctic latitudes. Speculations on the radiant distribution and possible meteor sources are presented.