bluuebunny/crossref_metadata_2025 huggingface dataset:
Testing and extending the unfolding model of voluntary turnover to it professionals
Authors: Niederman Fred , Sumner Mary , Maertz JR. Carl P.
Published: August 2007

This study examines the turnover decision processes of information technology (IT) personnel for the first time. Our theoretical guide for this investigation was the unfolding model of voluntary turnover (Lee & Mitchell, 1994), the preeminent turnover process model. Most of the 124 leavers used three new decision paths that shared the characteristic of including an alternative job search and evaluation; another significant number used the original five theorized paths. In sharp contrast to earlier findings on the unfolding model, the majority of respondents (88%) reported following paths not among the original five theorized paths.This result strongly suggests that IT professionals likely take numerous routes in deciding to leave current employment, most of which involve some search for and consideration of alternative jobs. A general conclusion for human resource managers is to assume that IT professionals are aware of alternative opportunities and to consider early interventions emphasizing the relative benefits of the current job over labor market competitors. © 2007 Wiley Periodicals, Inc.
Diagnostic value of mucins (MUC1, MUC2 and MUC5AC) expression profile in endoscopic ultrasound‐guided fine‐needle aspiration specimens of the pancreas
Authors: Wang Yi , Gao Jun , Li Zhaoshen , Jin Zhendong , Gong Yanfang , Man Xiaohua
Published: August 2007

Mucins are aberrantly expressed in various malignancies. We immunohistochemistrically tested mucins expression (MUC1, MUC2 and MUC5AC) in EUS‐FNA samples from pancreatic occupying lesions for the diagnostic utility. The prevalence of MUC1, MUC2 and MUC5AC expression in pancreatic cancers were 77.5% (31/40), 10.0% (4/40) and 80.0% (32/40), respectively, and in the benign pancreatic diseases 25% (4/16), 31.3% (5/16) and 43.8% (7/16). MUC1 and MUC5AC significantly overexpressed in pancreatic cancer, and MUC1 negatively related with tumor differentiation degree (p < 0.05). The prevalence of MUC1, MUC2 and MUC5AC expression in pancreatic mucinous neoplasms were 66.7% (12/18), 38.9% (7/18) and 88.9% (16/18), respectively, and in the pancreatic nonmucinous neoplasms 60.5% (23/38), 5.3% (2/38) and 57.9% (22/38). MUC2 and MUC5AC significantly overexpressed in pancreatic mucinous neoplasms, especially MUC2 in benign mucinous neoplasms (p < 0.05). Compared with cytology alone, the combination test of MUC1+cytology, and MUC5AC+cytology could achieve higher sensitivity (85 vs. 65%, 100 vs. 65%) and accuracy (89.3% vs. 73.2%, 91.1% vs. 73.2%) for pancreatic cancer diagnosis; the combination test of MUC2 + cytology, and MUC5AC + cytology could achieve higher sensitivity (77.8% vs. 38.9%, 100% vs. 38.9%), and specificity (97.4% vs. 60.5%, 71.1% vs. 60.5%) accuracy (100% vs. 51.8%, 80.4% vs. 51.8%) for mucinous neoplasm diagnosis. The panel MUC1+/MUC2−/MUC5AC+/ was higher specific in pancreatic cancer diagnosis, as well as MUC1−/MUC2+/MUC5AC+/ in pancreatic mucinous neoplasms. Our observations suggest the mucins expression profile in EUS‐FNA specimens has higher value for the diagnosis of pancreatic cancer and mucinous neoplasms. © 2007 Wiley‐Liss, Inc.
99mTc‐MIBI imaging for prediction of therapeutic effects of second‐generation MDR1 inhibitors in malignant brain tumors
Authors: Sasajima Toshio , Shimada Naoya , Naitoh Yuichiro , Takahashi Masataka , Hu Yi , Satoh Tomo , Mizoi Kazuo
Published: August 2007

The aim of this study was to explore whether99mTc‐methoxyisobutylisonitrile (99mTc‐MIBI) is suitable to elucidate multidrug resistance and prediction of potentiation of antitumor agents by second‐generation MDR1 inhibitors (PSC833, MS‐209) in malignant brain tumors in rat. Malignant tumor cells (RG2 and C6 gliomas, Walker 256 carcinoma) were incubated with low dose vincristine (VCR) to induce multidrug resistance. MTT assay demonstrated a significant increase of surviving fractions in VCR‐resistant sublines compared to those of drug‐naive cells. Reverse transcriptase polymerase chain reaction revealed higher expression of MDR1 mRNA in VCR‐resistant cells than drug‐naive cells in each line. Volume distribution (Vd) of99mTc‐MIBI was negatively correlated with MDR1 mRNA expression among drug‐naive and VCR‐resistant cells. MDR1 inhibitors decreased surviving fractions and increasedVdof99mTc‐MIBI significantly in VCR‐resistant sublines, whereas MDR1 mRNA expression was unchanged. These findings indicate that99mTc‐MIBI efflux was functionally suppressed by MDR1 inhibitors. Autoradiographic images of99mTc‐MIBI revealed higher uptake in drug‐naive cells at basal ganglia compared with VCR‐resistant cells at the opposite basal ganglia of rats. Oral administration of the second‐generation MDR1 inhibitors significantly increased99mTc‐MIBI accumulation of both tumors. Therapeutic effects of VCR with or without the MDR1 inhibitors were also evaluated autoradiographically using14C‐methyl‐L‐methionine (14C‐Met) and MIB‐5 index.14C‐Met uptake and MIB‐5 index of both tumors treated with VCR following the MDR1 inhibitor treatment significantly decreased compared with tumors treated with VCR alone. Analysis of99mTc‐MIBI accumulation is considered informative for detecting MDR1‐mediated drug resistance and for monitoring the therapeutic effects of MDR1 inhibitors in malignant brain tumors. © 2007 Wiley‐Liss, Inc.
Revised model core potentials of s‐block elements
Authors: Anjima Hidenori , Tsukamoto Shinya , Mori Hirotoshi , Mine Masaki , Klobukowski Mariusz , Miyoshi Eisaku
Published: August 2007

We developed new model core potentials (MCPs) for s‐block elements from Na to Ra, in which the outer core (n − 1)s and (n − 1)p electrons are treated explicitly together with the ns electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show excellent performance in describing the electronic structures of atoms and molecules, bringing about accurate ionization potentials of atoms and very good spectroscopic constants of ionic and covalent molecules. The results obtained with the new MCPs are very close to the ones obtained using the all‐electron correlation consistent basis sets of Dunning. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Quantitative computer simulations of biomolecules: A snapshot
Authors: Yang Wei , Nymeyer Hugh , Zhou Huan‐Xiang , Berg Bernd , Brüschweiler Rafael
Published: August 2007

A recent workshop titled “Quantitative Computational Biophysics” at Florida State University provided an overview of the state of the art in quantitative modeling of biomolecular systems. The presentations covered a wide range of interrelated topics, including the development and validation of force fields, the modeling of protein–protein interactions, the sampling of conformational space, and the assessment of equilibration and statistical errors. Substantial progress in all these areas was reported. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Interplay between chromatin remodelers and protein arginine methyltransferases
Authors: Pal Sharmistha , Sif Saïd
Published: August 2007

Chromatin modifying enzymes have emerged as key regulators of all DNA based processes, which control cell growth, development, and differentiation. Recently, it has become clear that different chromatin remodeling and histone‐modifying activities are involved in transcriptional activation and repression. Among the enzymes involved in regulating chromatin structure is the family of protein arginine methyltransferases (PRMTs) that specializes in methylating both histones as well as key cellular proteins. There are eleven different PRMT genes (PRMT1‐11) whose biological function remains under explored. PRMTs regulate various cellular processes such as DNA repair and transcription, RNA processing, signal transduction, and nucleo‐cytoplasmic localization. Like histone lysine methylation, methylation of histone arginine residues can either induce or inhibit transcription depending on the residue being modified and the type of methylation being introduced. In this review, we will focus on the latest findings and biological roles of ATP‐dependent chromatin remodeling complexes and PRMT enzymes, and how their aberrant expression is linked to cancer. J. Cell. Physiol. 213: 306–315, 2007. © 2007 Wiley‐Liss, Inc.
Tumor suppressor pRb2/p130 gene and its derived product Spa310 spacer domain as perspective candidates for cancer therapy
Authors: Giordano Antonio , Rossi Alessandra , Romano Gaetano , Bagella Luigi
Published: August 2007

Tumor suppressor pRb2/p130 gene belongs to the retinoblastoma (Rb) gene family, which also includes pRb/p105 and pRb/p107. The members of the Rb gene family have attracted a great deal of interest because of their essential role in regulating cell cycle and, consequently, cell proliferation. This mini review discusses the potential therapeutic applications both of pRb2/p130 and its derived product Spa310 spacer domain in cancer treatment. J. Cell. Physiol. 213: 403–406, 2007. © 2007 Wiley‐Liss, Inc.
Cell surface restriction of EGFR by a tenascin cytotactin‐encoded EGF‐like repeat is preferential for motility‐related signaling
Authors: Iyer Anand Krishnan V. , Tran Kien T. , Griffith Linda , Wells Alan
Published: August 2007

The 14th EGFL‐repeat (Ten14) of human tenascin cytotactin activates the epidermal growth factor receptor (EGFR) with micromolar affinity; however, unlike EGF, Ten14‐mediated activation of EGFR does not lead to receptor internalization. As the divergent signaling pathways downstream of EGFR have been shown to be triggered from plasma membrane and cytosolic locales, we investigated whether Ten14‐mediated surface restriction of EGFR resulted in altered biochemical and cellular responses as compared to EGF. Molecules associated with migratory cascades were activated to a relatively greater extent in response to Ten14, with very weak activation of proliferation‐associated cascades. Activation of phospholipase C γ (PLCγ) and m‐calpain, associated with lamellipod protrusion and tail retraction, respectively, were noted at even at sub‐saturating doses of Ten14. However, activation of ERK/MAPK, p90RSK, and Elk1, factors affecting proliferation, remained low even at high Ten14 concentrations. Similar activation profiles were observed for EGF‐treated cells at 4°C, a maneuver that limits receptor internalization. We demonstrate a concurrent effect of such altered signaling on biophysical responses—sustained migration was observed at levels of Ten14 that activated PLCγ, but did not stimulate proliferation significantly. Here, we present a novel class of EGFR ligands that can potentially signal as a part of the extracellular matrix, triggering specific intracellular signaling cascades leading to a directed cellular response from an otherwise pleiotropic receptor. This work extends the signaling paradigm of EGFL repeat being presented in a restricted fashion as part of the extracellular matrix. J. Cell. Physiol. 214: 504–512, 2008. © 2007 Wiley‐Liss, Inc.
Epidermal growth factor receptor‐dependent PI3K‐activation promotes restitution of wounded human gastric epithelial monolayers
Authors: Tétreault Marie‐Pier , Chailler Pierre , Beaulieu Jean‐Francois , Rivard Nathalie , Ménard Daniel
Published: August 2007

Restitution is a crucial event during the healing of superficial injury of the gastric mucosa involving epithelial cell sheet movement into the damaged area. We demonstrated that growth factors promote the restitution of human gastric epithelial cells. However, the intracellular signaling pathways that transmit extracellular cues as well as regulate basal and growth factor‐stimulated gastric epithelial cell migration are still unclear. Herein, confluent human gastric epithelial cell monolayers (HGE‐17) or primary cultures of gastric epithelial cells were wounded with a razor blade and the migration response was analyzed in presence or absence of TGFα or of pharmacological inhibitors of signaling proteins. Kinase activation profile analysis and phase‐contrast microscopy were also performed in parallel. We report that ERK1/2 and Akt activities are rapidly stimulated following wounding of HGE‐17 cells. Treatment of confluent HGE‐17 cells or primary cultures of gastric epithelial cells with the phosphatidylinositol 3‐kinase inhibitor LY294002, but not the MEK1 inhibitor, PD98059, significantly inhibits basal and TGFα‐induced migration following wounding. Conversely, treatment of wounded HGE‐17 cells with phosphatidylinositol(3,4,5)‐triphosphate is sufficient to stimulate basal cell migration by 235%. In addition, pp60c‐src kinase activity and tyrosine phosphorylation of epidermal growth factor receptors (EGFR) are also rapidly enhanced after wounding and pharmacological inhibition of both these activities strongly attenuates basal and TGFα‐induced migration as well as Akt phosphorylation levels. In conclusion, the present results indicate that EGFR‐dependent PI3K activation promotes restitution of wounded human gastric epithelial monolayers. J. Cell. Physiol. 214: 545–557, 2008. © 2007 Wiley‐Liss, Inc.
Ancient linkage of a POU class 6 and an anterior hox‐like gene in cnidaria: implications for the evolution of homeobox genes
Authors: Kamm Kai , Schierwater Bernd
Published: August 2007

Linkage analyses in metazoan genomes suggest two ancestral arrays for the majority of homeobox genes. The related homeobox genes and chromosomal regions that are dispersed in extant species derived possibly from only two single common ancestor regions. One proposed ancestral array, designated as ANTP mega‐array, contains most of the ANTP class homeobox genes; the second, named the contraHox super‐paralogon, would consist of the classes PRD, POU, LIM, CUT, prospero, TALE and SIX. Here, we report the tight linkage of a POU class 6 gene to an anterior Hox‐like gene in the hydrozoan Eleutheria dichotoma and discuss its possible significance for the evolution of homeobox genes. POU class 6 genes also seem to be ancestrally linked to the HoxC and A clusters in vertebrates, despite POU homeobox genes belonging to the contraHox paralogon. Hence, the much tighter linkage of a POU class 6 gene to an anterior Hox‐like gene in a cnidarian is possibly the evolutionary echo of an ancestral genomic region from which most metazoan homeobox classes emerged. J. Exp. Zool. (Mol. Dev. Evol.) 308B:777–784, 2007. © 2007 Wiley‐Liss, Inc.
Fatty acid composition of total lipids, neutral lipids and phospholipids in wild and farmed matrinxã (Brycon cephalus) in the Brazilian Amazon area
Authors: Almeida Neiva Maria , Franco Maria Regina Bueno
Published: August 2007

BACKGROUND: The chemical composition of Amazonian fish is extremely variable, being influenced by the season and the type and amount of food. A special interest in the fish oil composition has been developed owing to the presence of essential fatty acids, since this is directly related to human health. This study aimed to investigate the fatty acid composition (FAC) of the total lipid (TL), neutral lipid (NL) and phospholipid (PL) fractions of the dorsal muscle and orbital cavity of farmed and wild matrinxã in the Amazon area captured in different seasons.

RESULTS: Fatty acids (FA) were analysed by high‐resolution gas chromatography/mass spectrometry. Sixty‐five FA were detected in the TL, 66 in the NL and 55 in the PL. The main FA found in farmed and wild fish were oleic, palmitic, stearic and linoleic acids. No distinctions in the quality or quantity of these fractions between dorsal muscle and orbital cavity were found.

CONCLUSION: The season had a significant influence on the TL and FAC. Fish captured during the dry season showed lower levels of lipid and a higher percentage of long‐chain polyunsaturated fatty acids. Matrinxã farmed in a semi‐intensive system showed a nutritional quality comparable to that of wild matrinxã captured in the wet season. Copyright © 2007 Society of Chemical Industry
Effectiveness of organic acid, ozonated water and chlorine dippings on microbial reduction and storage quality of fresh‐cut iceberg lettuce
Authors: Akbas Meltem Yesilcimen , Ölmez Hülya
Published: August 2007

BACKGROUND: The comparative effects of organic (citric and lactic) acids, ozone and chlorine on the microbiological population and quality parameters of fresh‐cut lettuce during storage were evaluated.

RESULTS: Dipping of lettuce in 100 mg L−1 chlorine solution reduced the numbers of mesophilic and psychrotrophic bacteria and Enterobacteriaceae by 1.7, 2.0 and 1.6 log10 colony‐forming units (CFU) g−1 respectively. Treatment of lettuce with citric (5 g L−1) and lactic (5 mL L−1) acid solutions and ozonated water (4 mg L−1) reduced the populations of mesophilic and psychrotrophic bacteria by 1.7 and 1.5 log10 CFU g−1 respectively. Organic acid dippings resulted in lower mesophilic and psychrotrophic counts than ozonated water and chlorine dippings during 12 days of storage. Lactic acid dipping effectively reduced (by 2.2 log10 CFU g−1) and maintained low populations of Enterobacteriaceae on lettuce for the first 6 days of storage. No significant (P > 0.05) changes were observed in the texture and moisture content of lettuce samples dipped in chlorine, organic acids and ozonated water during storage. Colour, β‐carotene and vitamin C values of fresh‐cut iceberg lettuce did not change significantly (P > 0.05) until day 8.

CONCLUSION: Lactic and citric acid and ozonated water dippings could be alternative treatments to chlorine dipping to prolong the shelf life of fresh‐cut iceberg lettuce. Copyright © 2007 Society of Chemical Industry
Low performance of the MSKCC nomogram in preoperatively ultrasonically negative axillary lymph node in breast cancer patients
Authors: Zgajnar Janez , Perhavec Andraz , Hocevar Marko , Podkrajsek Maja , Hertl Kristijana , Frkovic‐Grazio Snjezana , Pohar Maja , Besic Nikola
Published: August 2007

Background and Objectives

In order to predict the nonsentinel lymph node (NSLN) metastases in sentinel lymph node (SLN) positive patients a nomogram was created at the Memorial Sloan Kettering Cancer Centre (MSKCC). The aim of our study was to validate the MSKCC nomogram in patients grouped by the preoperative ultrasound (US) examination of the axillary lymph nodes.

Methods

The MSKCC nomogram was validated separately in three groups of patients: (US‐0) only clinically preoperatively negative axillary lymph nodes (126 patients), (US‐1) US negative axillary lymph nodes (109 patients), and (US‐2) US suspicious but fine needle aspiration biopsy (FNAB) negative axillary lymph nodes (41 patients).

Results

The predicted probability underestimates the actual probability with the mean absolute error equal to 0.116 in the US‐0 group (P = 0.003), and overestimates the actual probability (mean absolute error equal to 0.084) in US‐1 group (P = 0.033) and US‐2 group (mean absolute error is 0.110) (P = 0.275).

Conclusion

We found that the MSKCC nomogram overestimates the probability of the NSLN metastases in breast cancer patients with (i) preoperatively US negative or (ii) US suspicious, but FNAB negative axillary lymph nodes. We also found that MSKCC nomogram has only limited value in patients with only clinically negative axillary lymph nodes. J. Surg. Oncol. 2007;96:547–553. © 2007 Wiley‐Liss, Inc.
Glomus tumor of the omentum: A case report
Authors: Matsuo Shigetoshi , Susumu Seiya , Tsutsumi Ryuji , Azuma Takashi , Obata Shirou , Hayashi Tomayoshi
Published: August 2007

Computed tomography revealed a well‐enhanced omental mass. Magnetic resonance imaging demonstrated a mass with low signal intensity on T1‐weighted images (WI) and high signal intensity on T2‐WI. Resected specimens immunohistochemically showed positive results for alpha‐smooth muscle actin, muscle‐specific actin (HHF35) and vimentin, and negative results for S‐100 protein, CD34, desmin, EMA, keratin, calretinin, HBME1, and c‐kit. This is the first case of an omental glomus tumor reported in the English literature. J. Surg. Oncol. 2007;96:633–636. © 2007 Wiley‐Liss, Inc.
Safety of modified double‐stapling end‐to‐end gastroduodenostomy in distal subtotal gastrectomy
Authors: Yang Han‐Kwang , Lee Hyuk‐Joon , Ahn Hye‐Sung , Yoo Moon‐Won , Lee In Kyu , Lee Kuhn Uk
Published: August 2007

Background and Objectives

Double‐stapling end‐to‐end gastroduodenostomy (DS‐BI) has several potential advantages over other anastomotic techniques in that it is a simple procedure, with no additional gastrotomy on the remnant stomach, and less tension on the anastomosis site. We evaluated the safety of DS‐BI by comparing it with the hand‐sewn Billroth II gastrojejunostomy (B‐II).

Methods

Medical records of 933 consecutive patients (DS‐BI 428, B‐II 505) who underwent distal subtotal gastrectomy were retrospectively reviewed. Several clinicopathological features and treatment results were compared between the two groups.

Results

The overall complication rates were 9.3% in the DS‐BI group and 15.2% in the B‐II group (P = 0.007). Anastomosis‐related complications, such as anastomosis‐site leakage, stenosis, and intraluminal bleeding, did not differ between the two groups (1.2% in the DS‐BI group and 1.8% in the B‐II group, P = 0.59). All the anastomosis‐related complications were managed conservatively. Postoperative mortality rates were 0% in the DS‐BI group and 0.4% (2/505) in the B‐II group.

Conclusions

Modified DS‐BI is a safe procedure, with short‐term results similar to those of hand‐sewn Billroth II anastomosis. J. Surg. Oncol. 2007;96:624–629. © 2007 Wiley‐Liss, Inc.
Elemental mercury poisoning probably causes cortical myoclonus
Authors: Ragothaman Mona , Kulkarni Girish , Ashraf Valappil V. , Pal Pramod K. , Chickabasavaiah Yasha , Shankar Susarla K. , Govindappa Srikanth S. , Satishchandra Parthasarthy , Muthane Uday B.
Published: August 2007

Mercury toxicity causes postural tremors, commonly referred to as “mercurial tremors,” and cerebellar dysfunction. A 23‐year woman, 2 years after injecting herself with elemental mercury developed disabling generalized myoclonus and ataxia. Electrophysiological studies confirmed the myoclonus was probably of cortical origin. Her deficits progressed over 2 years and improved after subcutaneous mercury deposits at the injection site were surgically cleared. Myoclonus of cortical origin has never been described in mercury poisoning. It is important to ask patients presenting with jerks about exposure to elemental mercury even if they have a progressive illness, as it is a potentially reversible condition as in our patient. © 2007 Movement Disorder Society
A South African mixed ancestry family with Huntington disease‐like 2: Clinical and genetic features
Authors: Bardien Soraya , Abrahams Fatima , Soodyall Himla , van der Merwe Lize , Greenberg Jacquie , Brink Tinus , Carr Jonathan
Published: August 2007

Huntington disease‐like 2 (HDL2) is a neurodegenerative disorder caused by an expansion of a CTG repeat in the junctophilin‐3 gene (JPH3). A limited number of HDL2 families have been reported, all of apparently Black African ancestry. We report on a South African family that presented with progressive dementia and a movement disorder affecting numerous family members. Genotyping of the JPH3 CTG repeat revealed pathogenic expansions in three affected individuals. Whereas HDL2 is thought to be clinically indistinguishable from Huntington disease (HD), 2 of the patients in this study presented with clinical symptoms that differed substantially from HD; one had myoclonus and the other had Parkinsonism. Moreover, brain magnetic resonance imaging scans of these patients showed imaging features atypical for HD. Mitochondrial DNA and Y‐chromosome DNA analysis on a family member showed that his maternal and paternal ancestries are typical of that found among the South African mixed ancestry or colored population. A difference in the distribution of CTG repeats between Caucasian and Black individuals was detected. We conclude that the phenotype of HDL2 is broad and can differ from that of typical HD. The diagnosis therefore should be considered in a wide spectrum of neuropsychiatric and abnormal movement presentations. © 2007 Movement Disorder Society
Abnormal brain tryptophan metabolism and clinical correlates in Tourette syndrome
Authors: Behen Michael , Chugani Harry T. , Juhász Csaba , Helder Emily , Ho Albert , Maqbool Mohsin , Rothermel Robert D. , Perry Jacquie , Muzik Otto
Published: August 2007

Symptoms in Tourette syndrome (TS) are likely related to abnormalities involving multiple neurotransmitter systems in striatal‐thalamo‐cortical circuitry. Although prior studies have found abnormal levels of tryptophan, serotonin, and their metabolites in blood, cerebrospinal fluid and brain tissue of TS patients, understanding of focal brain disturbances and their relationship to clinical phenotype remains poor. We used α‐[11C]methyl‐L‐tryptophan (AMT) positron emission tomography (PET) to assess global and focal brain abnormalities of tryptophan metabolism and their relationship to behavioral phenotype in 26 children with TS and nine controls. Group comparisons on regional cortical and subcortical AMT uptake revealed decreased AMT uptake in bilateral dorsolateral prefrontal cortical and bilaterally increased uptake in the thalamus (P = 0.001) in TS children. The ratio of AMT uptake in subcortical structures to dorsolateral prefrontal cortex was significantly increased bilaterally (P < 0.01) in TS patients also. Behaviorally defined subgroups within the TS sample revealed differences in the pattern of AMT uptake in the fronto‐striatal‐thalamic circuit. This study demonstrates cortical and subcortical abnormalities of tryptophan metabolism in TS and provides neuroimaging evidence for a role of serotonergic mechanisms in the pathophysiology of TS. © 2007 Movement Disorder Society
A hybrid‐cell EBG power plane for ultra‐wideband suppression of ground bounce noise
Authors: Kim D.‐Y. , Joo S.‐H. , Lee H.‐Y.
Published: August 2007

A new power/ground plane using the hybrid‐cell electromagnetic bandgap (EBG) structure is proposed for ultra‐wideband suppression of the ground bounce noise (GBN) in high‐speed digital circuit boards. The hybrid‐cell EBG structure achieves both a high series inductance and a shorter period of the EBG lattice. The −30 dB stop‐band of the proposed structure has about a 7.9‐GHz bandwidth and starts at 370 MHz where the GBN energy is dominantly distributed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2853–2855, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22831
A novel investigation on size reduction of a frequency selective surface
Authors: Pain M. K. , Bhunia S. , Biswas S. , Sarkar D. , Sarkar P. P.
Published: August 2007

The study presents theoretical and experimental investigation of a novel, reduced size Microstrip Frequency Selective Surface. The novel design is achieved by cutting some rectangular slots at four sides of a square patch. Compared with conventional square patch Frequency Selective Surface (FSS), this slotted square patch Microstrip FSS can achieve reduction in patch area of 36%. The structure acts like a band pass filter with a resonant frequency 8 GHz. Both theoretical and experimental investigations are done. Theoretical investigation is done by IE3D software. Experimental investigation is performed using standard microwave test bench. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2820–2821, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22833
A 2‐GHz fully‐differential CMOS power amplifier with virtual grounds to suppress ground bounce
Authors: Yan Tao , Liao Huailin , Li Chen , Huang Ru
Published: August 2007

This article presents a 2‐GHz fully‐differential CMOS power amplifier (PA) fabricated in a standard 0.35‐μm RF CMOS process. Virtual grounds are introduced at both drive‐stage and output‐stage transistors' sources of the two‐stage differential PA, which guarantees a stable reference ground and thus improves the PA performance. A performance of 15‐dB gain, 26.6 dBm Pout, and 26% PAE is achieved. At 15 dBm Pout, the ACPR1 and ACPR2 are −35.3 and −66.3 dBc, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2780–2784, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22849
Polymerizability, copolymerizability, and properties of cyanoacrylate‐telechelic polyisobutylenes II: copolymerization of three‐arm star cyanoacrylate‐ telechelic polyisobutylene with ethyl cyanoacrylate
Authors: Kwon Yongmoon , Kennedy Joseph P.
Published: August 2007

This research concerned the synthesis and characterization of novel conetworks containing polyisobutylene (PIB) and polyethyl‐2‐cyanoacrylate [poly(Et‐CA)] sequences. The syntheses involved the copolymerization of CA‐telechelic three‐arm star PIB [Ø(PIB‐CA)3] with ethyl‐2‐cyanoacrylate (Et‐CA) mediated by nucleophiles or by living tissue (fresh eggs). The conetworks were characterized by swelling in hexanes, tetrahydrofuran (THF), and acetone, and the results indicate co‐continuous PIB and poly(Et‐CA) domains. The conetworks exhibit two Tgs indicating phase‐separation between PIB and poly(Et‐CA). The outstanding oxidative resistance of the conetworks was demonstrated by exposure to concentrated nitric acid. The tensile strengths, moduli, and elongations of a series of conetworks with different overall compositions were investigated and the findings interpreted in terms of covalently linked rubbery and glassy domains. AFM also suggests the presence of phase‐separated rubbery and glassy domains. DMTA spectra of a Ø(PIB‐CA)3 homonetwork, and Ø(PIB‐CA)3/Et‐CA conetworks were analyzed and interpreted in terms of coexisting rubbery and glassy domains. Observations made during the exposure of Ø(PIB‐CA)3/Et‐CA mixtures to proteinaceous tissue, in combination with characterization data, were used to propose a structural model for the conetworks. Copyright © 2007 John Wiley & Sons, Ltd.
Degradation behaviors of monomethoxy poly(ethylene glycol)‐b‐poly(ε‐caprolactone) nanoparticles in aqueous solution
Authors: Shen Chunhua , Guo Shengrong , Lu Chengfei
Published: August 2007

Monomethoxy poly(ethylene glycol)‐b‐poly(ε‐caprolactone)(MPEG‐b‐PCL) diblock copolymers were synthesized via a ring‐opening polymerization. The polymeric nanoparticles prepared by precipitation/solvent evaporation exhibit a core–shell structure, characterized by dynamic light scattering (DLS), nuclear magnetic resonance (NMR), and atomic force microscopy (AFM). The hydrolytic degradation of those nanoparticles was studied by DLS, NMR, and gel permeation chromatography (GPC). It was found that the molecular weight of PCL block in a copolymer significantly affects the stability of nanoparticles in aqueous solution and nanoparticles with shorter PCL block length degraded faster. The degradation behaviors could be divided into two stages with slow degradation at the interface region via swelling effect and fast degradation at inner core via caves and channels formed by cleavage of ester bonds. Copyright © 2007 John Wiley & Sons, Ltd.
Cationic poly(methacryl oxyethyl trimethylammonium) and its poly(ethylene glycol)‐grafted analogue as capillary coating materials in electrophoresis
Authors: Wiedmer Susanne K. , Andersson Toni , Sündermann Marika , Riekkola Marja‐Liisa , Tenhu Heikki
Published: August 2007

Cationic polyelectrolytes were synthesized and used as semipermanent coating materials for capillaries in electrophoresis. The polyelectrolytes used were a homopolymer of poly(methacryl oxyethyl trimethylammonium chloride) (PMOTAC) and its poly(ethylene glycol) (PEG)‐grafted analogue. Two PMOTAC polyelectrolytes, with molar masses of 85,000 and 300,000 g/mol, and PEG‐grafted PMOTAC with a molar mass of 280,000 g/mol were synthesized and then characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. Attachment of the polyelectrolytes to the wall of the fused silica capillary for electrophoresis caused the electroosmotic flow (EOF) to reverse. The polyelectrolyte coatings were tested over the pH range 2–11 at different buffer ionic strengths, and the most stable and strongest anodic EOFs were obtained at acidic pH values with low ionic strength buffers. Between runs the capillary is merely rinsed for 2 or 3 min with the background electrolyte solution. With the PMOTAC coatings at pH values ≤5, the RSDs of the EOFs were less than 2.9% after 60 injections. The effects of the molar mass of the polycation and of PEGylation of PMOTAC on the interactions between the polycations and basic proteins were studied at acidic pH values. The differences in the effective electrophoretic mobilities, resolution values, and plate numbers of the proteins with the different coatings were due to the EOF, as demonstrated through calculations of reduced mobilities, relative resolution values, and relative plate numbers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2655–2663, 2007
Attract‐and‐kill strategy. Laboratory studies on hatched larvae of Culex pipiens
Authors: Michaelakis Antonios , Mihou Anastasia P , Koliopoulos George , Couladouros Elias A
Published: August 2007

The attract‐and‐kill strategy is a new pest management technique that presupposes the intelligent combination of an attracting agent (e.g. pheromone) and a killing agent (e.g. insecticide). In the present study, the potential combination of the microencapsulated synthetic oviposition pheromone 6‐acetoxy‐5‐hexadecanolide with an insecticide has been tested. Initially, polyurea microcapsules containing 6‐acetoxy‐5‐hexadecanolide, the synthetic mixture of diastereomers of the oviposition pheromone of the mosquito species Culex quinquefasciatus Say (Diptera: Culicidae), were studied. Laboratory bioassays were performed to confirm the bioactivity of the microencapsulated pheromone on the oviposition activity of Culex pipiens L. biotype molestus Førskal (Diptera: Culicidae) with the aim of determining the optimum dose for oviposition response. Its effect was dose dependent, revealing an optimum dose of 300 mg of dried microcapsules. Attractancy over time was also studied. The microencapsulated pheromone was found to be sufficiently attractive to gravid female mosquitoes for a period of 40 days. Finally, the combination of the synthetic pheromone with the control agent temephos showed both an acceptable oviposition activity and sufficient larvicidal effect. Copyright © 2007 Society of Chemical Industry
Development of a qualitative liquid chromatography/tandem mass spectrometric method for the detection of narcotics in urine relevant to doping analysis
Authors: Deventer Koen , Pozo Oscar J. , Van Eenoo Peter , Delbeke Frans T.
Published: August 2007

A new screening procedure for 18 narcotics in urine for anti‐doping purposes has been developed using liquid chromatography/triple quadrupole mass spectrometry (LC/MS). Electrospray ionization (ESI) was used as interface. Infusion experiments were performed for all substances to investigate their mass spectrometric behaviour in terms of selecting product specific ions. These product ions were then used to develop a tandem mass spectrometric method using selected reaction monitoring (SRM). For the LC/MS analysis, chromatography was performed on an octadecylsilane column. The total run time of the chromatographic method was 5.5 min. For the sample preparation prior to LC/MS analysis, the urine samples were liquid‐liquid extracted at pH 9.5 after overnight enzymatic hydrolysis. Two extraction solvents were evaluated: dichloromethane/methanol 9/1 (v/v), which is currently used for the extraction of narcotics, and diethyl ether, used for the extraction of steroids. With diethyl ether the detection limits for all compounds ranged between 0.5 and 20 ng/mL and with the mixture containing dichloromethane the detection limits ranged between 0.5 and 10 ng/mL. Taking into account the minimum required performance limits of the World Anti‐Doping Agency of 200 ng/mL for narcotics, diethyl ether can also be considered as extraction solvent for narcotics. Finally, the described method was applied to the analysis of urine samples previously found to contain narcotics by our routine gas chromatography/mass spectrometry (GC/MS) method. Copyright © 2007 John Wiley & Sons, Ltd.
Development of novel guanidino‐labelling derivatisation (GLaD) reagents for liquid chromatography/matrix‐assisted laser desorption/ionisation analysis
Authors: Brancia Francesco L. , Bereszczak Jessica Z. , Piatkowska Elzbieta , Delneri Daniela
Published: August 2007

A new generation of guanidino‐labelling (GLaD) reagents were developed for quantitative proteomics using offline microcapillary liquid chromatography (LC) matrix‐assisted laser desorption/ionisation mass spectrometry (MALDI‐MS). In order to reduce the unwanted overlapping between the isotopic envelopes of the two differentially labelled peptide ions, a novel synthetic route was described for production of both 13C‐ and 15N‐containing isotopomers of N,O‐dimethylisourea. The use of these types of isotopes has no deleterious effect on the retention times of both differentially labelled peptides during offline microbore reversed‐phase LC. In addition, the possibility to incorporate a mass difference of 4 Da can be exploited during post‐source decay analysis to generate product ion spectra in which fragment ions containing the modifications appear as doublets in the corresponding product ion spectra, thus facilitating identification of the C‐terminal fragment ions. Copyright © 2007 John Wiley & Sons, Ltd.
Peptide Fragment Ion Analyser (PFIA): a simple and versatile tool for the interpretation of tandem mass spectrometric data and de novo sequencing of peptides
Authors: Jagannath Swaminathan , Sabareesh Varatharajan
Published: August 2007

The software Peptide Fragment Ion Analyser (PFIA) aids in the analysis and interpretation of tandem mass spectrometric data of peptides. The software package has been designed to facilitate the analysis of product ions derived from acyclic and cyclic peptide natural products that possess unusual amino acid residues and are heavily post‐translationally modified. The software consists of two programmes: (a) PFIA‐I lists the amino acid compositions and their corresponding product ion types for ‘a queried m/z value’ (z = +1) and (b) PFIA‐II displays fragmentation pattern diagram(s) and lists all sequence‐specific product ion types for the protonated adduct of ‘a queried sequence’. The unique feature of PFIA‐II is its ability to handle cyclic peptides. The two programmes used in combination can prove helpful for deriving peak assignments in the de novo sequencing of novel peptides. Copyright © 2007 John Wiley & Sons, Ltd.
Diffusivity fractionations of HO/HO and HO/HO in air and their implications for isotope hydrology
Authors: Barkan Eugeni , Luz Boaz
Published: August 2007

We have determined the isotope effects of 17O and 18O substitution of 16O in H2O on molecular diffusivities of water vapor in air by the use of evaporation experiments. The derived diffusion fractionation coefficients 17αdiff and 18αdiff are 1.0146 ± 0.0002 and 1.0283 ± 0.0003, respectively. We also determined, for the first time, the ratio ln(17αdiff)/ln(18αdiff) as 0.5185 ± 0.0002. This ratio, which is in excellent agreement with the theoretical value of 0.5184, is significantly smaller than the ratio in vapor‐liquid equilibrium (0.529). We show how this new experimental information gives rise to 17O excess in meteoric water, and how it can be applied in isotope hydrology. Copyright © 2007 John Wiley & Sons, Ltd.
Identification of β‐sitosterol, stigmasterol and ergosterin in A. roxburghii using supercritical fluid extraction followed by liquid chromatography/atmospheric pressure chemical ionization ion trap mass spectrometry
Authors: Huang Liying , Zhong Tianhua , Chen Tianwen , Ye Zhao , Chen Guonan
Published: August 2007

β‐Sitosterol and stigmasterol are the most common phytosterols in traditional Chinese medicine. They have been proved to have many important bioactivities. To the best of our knowledge, this is the first report that β‐sitosterol, stigmasterol and ergosterol coexisting in A. roxburghii herbs can be simultaneously extracted by a supercritical fluid extraction (SFE) procedure; then a simple high‐performance liquid chromatography/atmospheric pressure chemical ionization ion trap mass spectrometry (HPLC/APCI/MS) method was developed for simultaneous identification and determination of these three compounds. The ion trap MS/MS detector was equipped with an atmospheric pressure chemical ionization source operating in the positive ion mode, APCI(+). The linear responses were obtained in the concentration range of 0.50–150 µg/mL (r = 0.9999) for ergosterol, 5–400 µg/mL (r = 0.9999) for stigmasterol, and 10–2000 µg/mL (r = 0.9998) for β‐sitosterol. An orthogonal L9 (33) test design was employed for optimization of the SFE process. Under the optimized conditions, i.e. pressure of 25 mPa, temperature of 45°C and ethanol as modifier, the concentrations of sterols in the extract were found to be 2.89% (g/g) for β‐sitosterol, 3.56% (g/g) for stigmasterol and 2.96% (g/g) for ergosterin. The SFE method was also compared with a previously developed Soxhlet extraction. The SFE method produced higher yields of sterols than that of the Soxhlet extraction. The proposed method has been successfully used for identification and quantitation of β‐sitosterol, stigmasterol and ergosterin in a real A. roxburghii sample. Copyright © 2007 John Wiley & Sons, Ltd.
Testing logistic regression coefficients with clustered data and few positive outcomes
Authors: Hunsberger Sally , Graubard Barry I. , Korn Edward L.
Published: August 2007

Applications frequently involve logistic regression analysis with clustered data where there are few positive outcomes in some of the independent variable categories. For example, an application is given here that analyzes the association of asthma with various demographic variables and risk factors using data from the third National Health and Nutrition Examination Survey, a weighted multi stage cluster sample. Although there are 742 asthma cases in all (out of 18 395 individuals), for one of the categories of one of the independent variables there are only 25 asthma cases (out of 695 individuals). Generalized Wald and score hypothesis tests, which use appropriate cluster‐level variance estimators, and a bootstrap hypothesis test have been proposed for testing logistic regression coefficients with cluster samples. When there are few positive outcomes, simulations presented in this paper show that these tests can sometimes have either inflated or very conservative levels. A simulation‐based method is proposed for testing logistic regression coefficients with cluster samples when there are few positive outcomes. This testing methodology is shown to compare favorably with the generalized Wald and score tests and the bootstrap hypothesis test in terms of maintaining nominal levels. The proposed method is also useful when testing goodness‐of‐fit of logistic regression models using deciles‐of‐risk tables. Published in 2007 by John Wiley & Sons, Ltd.
The cost of checking proportional hazards
Authors: Shepherd Bryan E.
Published: August 2007

Confidence intervals (CIs) and the reported predictive ability of statistical models may be misleading if one ignores uncertainty in the model selection procedure. When analyzing time‐to‐event data using Cox regression, one typically checks the proportional hazards (PH) assumption and subsequently alters the model to address any violations. Such an examination and correction constitute a model selection procedure, and, if not accounted for, could result in misleading CI. With the bootstrap, I study the impact of checking the PH assumption using (1) data to predict AIDS‐free survival among HIV‐infected patients initiating antiretroviral therapy and (2) simulated data. In the HIV study, due to non‐PH, a Cox model was stratified on age quintiles. Interestingly, bootstrap CIs that ignored the PH check (always stratified on age quintiles) were wider than those which accounted for the PH check (on each bootstrap replication PH was tested and corrected through stratification only if violated). Simulations demonstrated that such a phenomenon is not an anomaly, although on average CIs widen when accounting for the PH check. In most simulation scenarios, coverage probabilities adjusting and not adjusting for the PH check were similar. However, when data were generated under a minor PH violation, the 95 per cent bootstrap CI ignoring the PH check had a coverage of 0.77 as opposed to 0.95 for CI accounting for the PH check. The impact of checking the PH assumption is greatest when thep‐value of the test for PH is close to the test's chosen Type I error probability. Copyright © 2007 John Wiley & Sons, Ltd.
A Bayesian hierarchical modeling approach for studying the factors affecting the stage at diagnosis of prostate cancer
Authors: Zhou Huafeng , Lawson Andrew B. , Hebert James R. , Slate Elizabeth H. , Hill Elizabeth G.
Published: August 2007

We extend the baseline‐category logits model for categorical response data to accommodate two distinct kinds of clustering. Our extension introduces random effects that have one component exhibiting spatial dependence and a second component that is distributed independently. We use this enhanced categorical logits model for investigating the factors that affect the geographical distribution of the diagnostic stage of prostate cancer (PrCA) in South Carolina (SC). Using incidence data from the SC registry, we fit three types of models: the baseline‐category logits model, the proportional odds model, and the adjacent‐categories logits model, each incorporating our two‐component random effects. The deviance information criterion (DIC) is used for selecting the best‐fitting model. The results from the best model are presented and interpreted. The county‐specific random effects are mapped to characterize the spatial distribution pattern of diagnostic stage of PrCA in the study region. In terms of spatial distribution of the diagnostic stage of PrCA, an area of excess (unexplained) risk was found in the north‐west area, and an area of low excess risk in the north‐east area for regional‐stage cancer in SC was identified through the analysis of the cancer registry data. Copyright © 2007 John Wiley & Sons, Ltd.
Estimation and prediction in linear mixed models with skew‐normal random effects for longitudinal data
Authors: Lin Tsung I. , Lee Jack C.
Published: August 2007

This paper extends the classical linear mixed model by considering a multivariate skew‐normal assumption for the distribution of random effects. We present an efficient hybrid ECME‐NR algorithm for the computation of maximum‐likelihood estimates of parameters. A score test statistic for testing the existence of skewness preference among random effects is developed. The technique for the prediction of future responses under this model is also investigated. The methodology is illustrated through an application to Framingham cholesterol data and a simulation study. Copyright © 2007 John Wiley & Sons, Ltd.