bluuebunny/crossref_metadata_2025 huggingface dataset:
Vitreous cryo‐sectioning of cells facilitated by a micromanipulator
Authors: LADINSKY MARK S. , PIERSON JASON M. , McINTOSH J. RICHARD
Published: December 2006

Sectioning vitrified cells and tissues for cryo‐electron microscopy is more challenging than room‐temperature sectioning of plastic‐embedded samples. As the sample must be kept very cold (<−130 °C) and because there is no liquid upon which the sections can float as they are cut, transferring the sections from the knife edge to a grid is one of the more difficult steps in the process. We employed a micromanipulator to hold and control the cryo‐sections as they come off the knife. This allows slower cutting speeds than are typically used in vitreous cryo‐sectioning and contributes to better control during cutting, which facilitates repeatable placement of a ribbon of sections onto a grid. The ribbon is kept under tension during the entire cutting process, which may decrease folding and/or compression, features that are inherent to vitreous sections. Furthermore, the added control afforded by this technique makes it easier for multiple ribbons to be placed on a single grid, thereby increasing the number of sections that can be examined and imaged during a microscopy session. It even allows for serial cryo‐electron microscopy. As such, this approach is an advance in the cryo‐microtomy of vitreous sections.
Differential Capacities of Outer Membrane Proteins from Neisseria meningitidis B to Prime the Murine Immune System after Vaccination
Authors: Silva Junior F. C. , Gioia C. A. C. , Oliveira J. M. , Cruz S. C. , Frasch C. E. , Milagres L. G.
Published: December 2006

Understanding the specificity of antibody response to Neisseria meningitidis serogroup B (Men B) is a key requirement for the development of an effective vaccine. This study was designed to investigate the antigen specificity of murine IgG1 and IgG2b antibodies induced by different primary immunization schedules and the booster dose with the Cuban Men B vaccine. Immunoblotting analyses were performed using outer membrane vesicles (OMV) from the vaccine strain (B:4,7:P1.19,15). IgG subclasses binding to PorA, PorB and RmpM were determined by digital scanning of the immunoreactive bands. Bactericidal antibody response after vaccination was also evaluated. The results indicated that IgG2b anti‐PorA was the main antibody response induced by two doses of the vaccine. A primary series of three doses was found important for increasing IgG2b as well as IgG1 to PorB and RmpM. The fourth dose favoured the recognition of RmpM as detected by the increase of specific IgG1 and IgG2b. IgG subclasses anti‐PorA did not change significantly if animals received two, three or four doses of the vaccine during the primary immunization or after the booster dose for all vaccine groups. The booster response to PorB and RmpM of groups BC2 and BC3 showed a significant increase in IgG2b levels compared with the primary response. However, the recall and the primary response of group BC4 were similar, suggesting a saturated dose–effect response after four doses of vaccine. The same was seen for bactericidal antibody response when human complement source was used in the assay.
Family system characteristics and psychological adjustment to cancer susceptibility genetic testing: a prospective study
Authors: Van Oostrom I , Meijers‐Heijboer H , Duivenvoorden HJ , Bröcker‐Vriends AHJT , Van Asperen CJ , Sijmons RH , Seynaeve C , Van Gool AR , Klijn JGM , Tibben A
Published: December 2006

This study examined prospectively the contribution of family functioning, differentiation to parents, family communication and support from relatives to psychological distress in individuals undergoing genetic susceptibility testing for a known familial pathogenic BRCA1/2 or Hereditary nonpolyposis colorectal cancer‐related mutation. Family functioning, differentiation to parents, hereditary cancer‐related family communication and perceived support from relatives were assessed in 271 participants for genetic testing before test result disclosure. Hereditary cancer distress (assessed by the Impact of Event Scale) and cancer worry (assessed by the Cancer Worry Scale) were assessed before, 1 week after, and 6 months after test result disclosure. Participants reporting more cancer‐related distress over the study period more frequently perceived the communication about hereditary cancer with relatives as inhibited, the nuclear family functioning as disengaged‐rigid or enmeshed‐chaotic, the support from partner as less than adequate and the relationship to mother as less differentiated. Especially, open communication regarding hereditary cancer and partner support may be important buffers against hereditary cancer distress. Identifying individuals with insufficient sources of support and addressing the family communication concerning hereditary cancer in genetic counseling may help the counselee to adjust better to genetic testing.
Co‐existence of two functional mutations on the same allele of the human ferrochelatase gene in erythropoietic protoporphyria
Authors: Di Pierro E , Brancaleoni V , Moriondo V , Besana V , Cappellini MD
Published: December 2006

Erythropoietic protoporphyria (EPP) is an autosomal dominant disease with incomplete penetrance due to reduced activity of ferrochelatase (FECH), a mitochondrial enzyme that catalyzes the final step of the heme biosynthetic pathway. The clinical phenotype of EPP results from co‐inheritance of a mutated allele and a wild‐type low‐expressed allele of the FECH gene. To date, more than 88 different mutations have been identified in the FECH gene of patients with EPP. There are evidences suggesting that an entire haplotype (−251G, IVS1–23T and IVS3–48C) reduces allele expression. In this study, we searched for the −251A/G, IVS1–23C/T and IVS3–48T/C polymorphisms in two unrelated Italian families with EPP. In all the patients, carrying the −250G>C mutation in the promoter region, the IVS3–48C on the other allele showed apparent homozygosity and absence of Mendelian segregation. By RNA and long polymerase chain reaction analysis, we identified a deletion of 5576 bp (g12490_18067), including exons 3 and 4, in cis with the −250G>C mutation in the promoter.
Patients’ willingness to pay for anti‐emetic treatment
Authors: Kerger H. , Turan A. , Kredel M. , Stuckert U. , Alsip N. , Gan T. J. , Apfel C. C.
Published: December 2006

Background:  Post‐operative nausea and vomiting (PONV) is a common complication of anaesthesia. This study was conducted in 100 German and 100 Turkish patients scheduled for elective surgery under general anaesthesia to assess the amount patients were willing to pay for an anti‐emetic that completely prevented PONV.

Methods:  Post‐operatively, using Dixon’s up and down method, patients completed an interactive computer questionnaire with a random starting point to determine how much of their own money they were willing to pay for a totally effective anti‐emetic treatment.

Results:  On average, participants were willing to pay €65 in Germany and €68 in Turkey to avoid PONV. However, patients who actually experienced PONV were willing to pay larger amounts: €96 in Germany and €99 in Turkey. The amount patients were willing to pay was related to female sex, history of motion sickness, non‐smoking status and better education.

Conclusions:  Despite differences in political and cultural origin, health care system and financial background, the amount patients were willing to pay for an effective anti‐emetic was similar in both Germany and Turkey to that reported previously for the USA.
OPTIMAL DIVIDEND POLICY WITH MEAN‐REVERTING CASH RESERVOIR
Authors: Cadenillas Abel , Sarkar Sudipto , Zapatero Fernando
Published: December 2006

Motivated by empirical evidence and economic arguments, we assume that the cash reservoir of a financial corporation follows a mean reverting process. The firm must decide the optimal dividend strategy, which consists of the optimal times and the optimal amounts to pay as dividends. We model this as a stochastic impulse control problem, and succeed in finding an analytical solution. We also find a formula for the expected time between dividend payments. A crucial and surprising economic result of our paper is that, as the dividend tax rate decreases, it is optimal for the shareholders to receive smaller but more frequent dividend payments. This results in a reduction of the probability of default of the firm.
Cohesion or confusion? Towards a typology for organizational learning research1
Authors: Shipton Helen
Published: December 2006

The study of organizational learning is no longer in its infancy. Since Cyert and March first introduced the notion in the early 1960s, a plethora of books and journal publications have presented their own interpretations of the meaning and significance of the term. Despite such endeavours, there is little common agreement about what organizational learning represents and how future research may build cumulatively upon the many diverse ideas articulated. The intention here is by no means to address these issues, which have been comprehensively examined elsewhere. The purpose is rather to compare and contrast approaches in order to analyse similarities and dissimilarities, together with research challenges, for each approach. This is achieved by presenting a comparative framework to categorize the literature according to (a) its prescriptive/explanatory bias and (b) in line with the level of analysis, examining whether there is a focus on the organization as a whole or upon individuals and their work communities instead. The review concludes by presenting some preliminary suggestions for cross‐quadrant research.
Home Bias, Foreign Mutual Fund Holdings, and the Voluntary Adoption of International Accounting Standards
Authors: COVRIG VICENTIU M. , DEFOND MARK L. , HUNG MINGYI
Published: December 2006

We test the assertion that a consequence of voluntarily adopting International Accounting Standards (IAS) is the enhanced ability to attract foreign capital. Using a unique database that reports firm‐level holdings of over 25,000 mutual funds from around the world, our multivariate tests find that average foreign mutual fund ownership is significantly higher among IAS adopters. We also find that IAS adopters in poorer information environments and with lower visibility have higher levels of foreign investment, consistent with firms using IAS adoption to provide more information and/or information in a more familiar form to foreign investors. Taken together, our findings are consistent with voluntary IAS adoption reducing home bias among foreign investors and thereby improving capital allocation efficiency.
Does the Association Between Alcohol Consumption and Depression Depend on How They Are Measured?
Authors: Graham Kathryn , Massak Agnes , Demers Andrée , Rehm Jürgen
Published: December 2006

Background: Inconsistent findings regarding the relationship between alcohol consumption and depression, including whether the relationship is J‐shaped or U‐shaped, may be at least partly due to the types of measures used for both alcohol consumption and depression.

Methods: We conducted a general population survey using random digit dialing (RDD) and computer‐assisted telephone interviewing (CATI) with 6,009 males and 8,054 females aged 18 to 76 years. The survey included 4 types of alcohol measures (frequency, usual and maximum quantity per occasion, volume, and heavy episodic drinking) covering both the past week and the past year, and 2 types of depression measures (meeting DSM criteria for a clinical diagnosis of major depression, recent depressed affect).

Results: The overall relationship between depression and alcohol consumption did not vary by gender or type of depression measure but did vary significantly by type of alcohol measure, with the strongest relationship found for heavy episodic drinking and high quantity per occasion. There were also significant gender interactions with both depression and alcohol measures, with females showing a stronger relationship than males when depression was measured as meeting the criteria for major depression and when alcohol consumption was measured as quantity per occasion or heavy episodic drinking. There was some evidence of a J‐shaped relationship, that is, greater depression among abstainers compared with those who usually drank 1 drink and never drank as much as 5 drinks for both former drinkers and lifetime abstainers when depression was measured as recent symptoms of depression but the J shape was found only for former drinkers when depression was measured as meeting the criteria for major depression and did not reach statistical significance in some analyses.

Conclusions: The results of the present study suggest that measurement and gender are key issues in interpreting findings on the relationship between alcohol and depression. First, depression is primarily related to drinking larger quantities per occasion, less related to volume, and unrelated to drinking frequency, and this effect is stronger for women than for men. Second, the overall relationship between depression and alcohol consumption is stronger for women than for men only when depression is measured as meeting a clinical diagnosis of major depression and not when measured as recent depressed affect. Finally, while there was some evidence that former drinkers had slightly higher rates of major depression and higher scores on recent depressed affect compared with light drinkers, there was no evidence that light drinking was protective for major depression when compared with lifetime abstainers, although light drinkers did report fewer recent symptoms of depressed affect.
Ethanol Self‐Administration and Alterations in the Livers of the Cynomolgus Monkey, Macaca fascicularis
Authors: Ivester Priscilla , Jackson Roberts L. , Young Tracey , Stafforini Diana , Vivian Jeffrey , Lees Cynthia , Young Jennifer , Daunais James , Friedman David , Rippe Richard A. , Parsons Christopher J. , Grant Kathleen A. , Cunningham Carol
Published: December 2006

Background: Most of the studies of alcoholic liver disease use models in which animals undergo involuntary administration of high amounts of ethanol and consume diets that are often high in polyunsaturated fatty acids. The objectives of this study were (1) to evaluate whether cynomolgus monkeys (Macaca fascicularis) drinking ethanol voluntarily and consuming a diet with moderate amounts of lipid would demonstrate any indices of alcoholic liver disease past the fatty liver stage and (2) to determine whether these alterations were accompanied by oxidative stress.

Methods: Six adult male and 6 adult female cynomolgus monkeys were allowed to consume ethanol voluntarily for 18 to 19 months. Additional monkeys were maintained on the same consumption protocol, but were not provided with ethanol. During the course of the study, liver biopsy samples were monitored for lipid deposition and inflammation, serum for levels of liver enzymes, and urine for concentrations of the isoprostane (IsoP) metabolite, 2,3‐dinor‐5,6‐dihydro‐15‐F2t‐IsoP, a biomarker for oxidative stress. Liver mitochondria were monitored for respiratory control and liver for concentrations of neutral lipids, adenine nucleotides, esterified F2 isoprostanes, oxidized proteins, 4‐hydroxynonenal (HNE)‐protein adducts, and protein levels of cytochrome P‐450 2E1 and 3A4.

Results: Ethanol consumption ranged from 0.9 to 4.05 g/kg/d over the period of the study. Serum levels of aspartate amino transferase were elevated in heavy‐consuming animals compared with those in ethanol‐naïve or moderate drinkers. Many of the ethanol consumers developed fatty liver and most showed loci of inflammation. Both hepatic energy charge and phosphorylation potential were decreased and NADH‐linked respiration was slightly, but significantly depressed in coupled mitochondria as a result of heavy ethanol consumption. The urinary concentrations of 2,3‐dinor‐5,6‐dihydro‐15‐F2t‐IsoP increased as high as 33‐fold over that observed in ethanol‐abstinent animals. Liver cytochrome P‐450 2E1 concentrations increased in ethanol consumers, but there were no ethanol‐elicited increases in hepatic concentrations of the esterified F2 isoprostanes, oxidized proteins, or HNE‐protein adducts.

Conclusion: Our studies show that cynomolgus monkeys undergoing voluntary ethanol consumption for 1.5 years exhibit many of the features observed in the early stages of human alcoholic liver disease. Ethanol‐elicited fatty liver, inflammation, and elevated serum aspartate amino transferase were evident with a diet that contained modest amounts of polyunsaturated lipids. The dramatic increases in urinary IsoP demonstrated that the animals were being subjected to significant oxidative stress that correlated with their level of ethanol consumption.
Do your patients suffer from excessive yawning?
Authors: Gutiérrez‐Álvarez Á. M.
Published: December 2006

Objective:  Yawning has been described in relation to drugs such as serotonin reuptake inhibitors, levodopa, dopamine agonists, MAO B inhibitor, morphine, methadone, buprenorphine, dextromethorphan, benzodiazepine, lidocaine, and flecaine. This is a report of two patients, on long‐term escitalopram therapy (more than 8 weeks) with stable dosing, who presented excessive yawning. Escitalopram is widely used in major depressive disorder and generalized anxiety disorder.

Method:  A clinical description of two cases.

Results:  Two females (62 and 59 years old, respectively) developed excessive daytime yawning. It was not associated with sedation or a feeling of needing sleep. The dosage was reduced and yawning disappeared some hours later. The patients’ depression did not recur.

Conclusion:  Yawning has been described in relation to different selective serotonin reuptake inhibitors and remitted following their discontinuation; it is interesting that the reported yawning in these two cases disappeared with the reduction of dosage, rather than the interruption of treatment.
Advanced glycation end products induce actin rearrangement and subsequent hyperpermeability of endothelial cells THIS ARTICLE HAS BEEN RETRACTED
Authors: GUO XIAO‐HUA , HUANG QIAO‐BING , CHEN BO , WANG SHU‐YUN , LI QIANG , ZHU YAN‐JUN , HOU FAN‐FAN , FU NING , BRUNK ULF T. , ZHAO MING
Published: December 2006

This study aimed to determine the effects of advanced glycation end products (AGEs) on endothelial cytoskeleton morphology and permeability, and to detect the underlying signaling mechanisms involved in these responses. Cultured endothelial cells (ECs) were exposed to AGE‐modified human serum albumin (AGE‐HSA), and EC cytoskeletal changes were evaluated by observing fluorescence of F‐actin following ligation with labeled antibodies. Endothelial permeability was detected by measuring the flux of TRITC‐albumin across the EC monolayers. To explore the signaling pathways behind AGE‐induced EC alteration, ECs were treated with either soluble anti‐AGE receptor (RAGE) IgG, or the MAPK inhibitors PD98059 and SB203580 before AGE‐HSA administration. To further elucidate possible involvement of the ERK and p38 pathways in AGE‐induced EC changes, adenovirus‐carried recombinant constitutive dominant‐negative forms of upstream ERK and p38 kinases, namely MEK1(A) and MKK6b(A), were pre‐infected into ECs 24 h prior to AGE‐HSA exposure. AGE‐HSA induced actin cytoskeleton rearrangement, as well as EC hyperpermeability, in a dose and time‐dependent manner. The effects were attenuated in cells pretreated with anti‐RAGE IgG, PD98059 or SB203580, respectively. EC pre‐infection with MEK1(A) and MKK6b(A) also alleviated the effect of AGEs. Furthermore, adenovirus‐mediated administration of activated forms of either MEK1 or MKK6b alone induced rearrangement of F‐actin and hyperpermeability. The results indicate that ERK and p38 MAPK play important roles in the mediation of AGE‐induced EC barrier dysfunction associated with morphological changes of the F‐actin.
Levels and interactions of plasma xanthine oxidase, catalase and liver function parameters in Nigerian children with Plasmodium falciparum infection
Authors: IWALOKUN B. A. , BAMIRO S. B. , OGUNLEDUN A.
Published: December 2006

Elevated plasma levels of xanthine oxidase and liver function parameters have been associated with inflammatory events in several human diseases. While xanthine oxidase provides in vitro protection against malaria, its pathophysiological functions in vivo and interactions with liver function parameters remain unclear. This study examined the interactions and plasma levels of xanthine oxidase (XO) and uric acid (UA), catalase (CAT) and liver function parameters GOT, GPT and bilirubin in asymptomatic (n=20), uncomplicated (n=32), and severe (n=18) falciparum malaria children aged 3–13 years. Compared to age‐matched control (n=16), significant (p<0.05) elevation in xanthine oxidase by 100–550%, uric acid by 15.4–153.8%, GOT and GPT by 22.1–102.2%, and total bilirubin by 2.3–86% according to parasitaemia (geometric mean parasite density (GMPD)=850–87100 parasites/μL) was observed in the malarial children. Further comparison with control revealed higher CAT level (16.2±0.5 vs 14.6±0.4 U/L; p<0.05) lacking significant (p>0.05) correlation with XO, but lower CAT level (13.4–5.4 U/L) with improved correlations (r=−0.53 to −0.91; p<0.05) with XO among the asymptomatic and symptomatic malaria children studied. 75% of control, 45% of asymptomatic, 21.9% of uncomplicated, and none of severe malaria children had Hb level>11.0 g/dL. Multivariate analyses further revealed significant (p<0.05) correlations between liver function parameters and xanthine oxidase (r=0.57–0.64) only in the severe malaria group. We conclude that elevated levels of XO and liver enzymes are biochemical features of Plasmodium falciparum parasitaemia in Nigerian children, with both parameters interacting differently to modulate the catalase response in asymptomatic and symptomatic falciparum malaria.
Primary cutaneous adenomyoepithelioma
Authors: Clarke Loren E. , Seykora John T.
Published: December 2006

An 83‐year‐old Caucasian woman presented to her dermatologist with a 5‐cm subcutaneous tumor on her right thigh. The lesion had been present for many years, but had recently enlarged. Incisional biopsy showed a multinodular tumor composed of variably sized glands comprised of a luminal layer of epithelial cells surrounded by one or more layers of myoepithelial cells. The histopathologic features resembled those of adenomyoepithelioma, an uncommon neoplasm usually encountered within the breast. Primary cutaneous adenomyoepithelioma is very rare yet shares histopathologic features with common cutaneous lesions such as spiradenomas and benign mixed tumors (chondroid syringomas). Primary cutaneous adenomyoepithelioma is part of the spectrum of epithelial‐myoepithelial tumors that includes benign mixed tumor, myoepithelioma and myoepithelial carcinoma. This rare tumor may mimic malignant lesions including metastatic adenocarcinoma. Like its breast counterpart, primary cutaneous adenomyoepithelioma should probably be regarded as a neoplasm of borderline malignant potential.
Immunostaining for MART‐1 in the interpretation of problematic intra‐epidermal pigmented lesions
Authors: Wiltz Katy L. , Qureshi Hina , Patterson James W. , Mayes Daniel C. , Wick Mark R.
Published: December 2006

The histopathologic distinction between pigmented actinic keratosis (PAK) and atypical junctional melanocytic proliferations (AJMP) is a common problem, and it is one with meaningful clinical significance. Previous publications have suggested that Melanocyte Antigen Related to T‐cells‐1 (MART‐1) – a melanocytic marker related to host immune response – was not useful in making this interpretative separation. To revisit that assertion, the authors selected 68 specimens that concerned the diagnosis of PAK vs. AJMP. The degree of morphologic difficulty attached to each case was rated semiquantitatively using a three‐tiered scale, and interpretative problems were caused by cytologic similarity between atypical keratinocytes and aberrant melanocytes, obscuring lichenoid inflammation, subepidermal fibrosis, and an absence of clearly defined cell nests at the dermoepidermal junction. Each biopsy sample was immunostained for MART‐1 (using antibody clone A103) with azure‐B counterstaining; the principal criterion for a diagnosis of AJMP was that of confluent cellular positivity over at least 1 high‐power (×400) microscopic field, in conjunction with nested cell growth. The specimens were then re‐examined diagnostically. Immunostaining definitely improved interpretative certitude in 65 examples (96% effectiveness); the final diagnosis was that of PAK for 21 lesions and AJMP for 47. Three specimens – all of which represented AJMP – did not benefit by MART‐1 staining. It is concluded that MART‐1 immunostaining with azure‐B counterstaining is a useful adjunct in the interpretation of problematic intra‐epidermal pigmented lesions.
Late‐onset Ito’s nevus: An uncommon acquired dermal melanocytosis
Authors: Mataix Javier , López Norberto , Haro Rosario , González Elena , Angulo Jorge , Requena Luis
Published: December 2006

Dermal melanocytoses comprise a variety of congenital and acquired conditions characterized by a sparse population of intradermal dendritic, variably pigmented, spindle‐shaped melanocytes. While Mongolian spot, Ota’s and Ito’s nevi are usually present at birth or appear around puberty; acquired dermal melanocytoses that appear in adult life are extremely rare. They include the facial lesions of acquired bilateral nevus of Ota‐like macules, also named Hori’s nevus, and the acquired unilateral nevus of Ota, also known as Sun’s nevus. Uncommon extrafacial examples of acquired dermal melanocytoses include lesions involving upper extremities, wrist, back, lower extremities and dorsal aspects of the hands and feet. They are more prevalent among Asian women. In general, dermal melanocytoses are rare lesions in Caucasian patients and acquired variants are exceedingly uncommon. We report a rare example of acquired Ito’s nevus that appeared in a Caucasian elderly woman and review the literature about acquired dermal melanocytoses.
Crystal structures of CbiL, a methyltransferase involved in anaerobic vitamin B12 biosynthesis, and CbiL in complex with S‐adenosylhomocysteine − implications for the reaction mechanism
Authors: Wada Kei , Harada Jiro , Yaeda Yuki , Tamiaki Hitoshi , Oh‐oka Hirozo , Fukuyama Keiichi
Published: December 2006

During anaerobic cobalamin (vitamin B12) biosynthesis, CbiL catalyzes methylation at the C‐20 position of a cyclic tetrapyrrole ring using S‐adenosylmethionine as a methyl group source. This methylation is a key modification for the ring contraction process, by which a porphyrin‐type tetrapyrrole ring is converted to a corrin ring through elimination of the modified C‐20 and direct bonding of C‐1 to C‐19. We have determined the crystal structures of Chlorobium tepidum CbiL and CbiL in complex with S‐adenosylhomocysteine (the S‐demethyl form of S‐adenosylmethionine). CbiL forms a dimer in the crystal, and each subunit consists of N‐terminal and C‐terminal domains. S‐Adenosylhomocysteine binds to a cleft between the two domains, where it is specifically recognized by extensive hydrogen bonding and van der Waals interactions. The orientation of the cobalt‐factor II substrate was modeled by simulation, and the predicted model suggests that the hydroxy group of Tyr226 is located in close proximity to the C‐20 atom as well as the C‐1 and C‐19 atoms of the tetrapyrrole ring. These configurations allow us to propose a catalytic mechanism: the conserved Tyr226 residue in CbiL catalyzes the direct transfer of a methyl group from S‐adenosylmethionine to the substrate through an SN2‐like mechanism. Furthermore, the structural model of CbiL binding to its substrate suggests the axial residue coordinated to the central cobalt of cobalt‐factor II.
Presynaptic plasma membrane Ca2+ ATPase isoform 2a regulates excitatory synaptic transmission in rat hippocampal CA3
Authors: Jensen Thomas P. , Filoteo Adelaida G. , Knopfel Thomas , Empson Ruth M.
Published: December 2006

Plasma membrane calcium ATPase isoforms (PMCAs) are expressed in a wide variety of tissues where cell‐specific expression provides ample opportunity for functional diversity amongst these transporters. The PMCAs use energy derived from ATP to extrude submicromolar concentrations of intracellular Ca2+ ([Ca2+]i) out of the cell. Their high affinity for Ca2+ and the speed with which they remove [Ca2+]i depends upon splicing at their carboxy (C)‐terminal site. Here we provide biochemical and functional evidence that a brain‐specific, C‐terminal truncated and therefore fast variant of PMCA2, PMCA2a, has a role at hippocampal CA3 synapses. PMCA2a was enriched in forebrain synaptosomes, and in hippocampal CA3 it colocalized with the presynaptic marker proteins synaptophysin and the vesicular glutamate transporter 1, but not with the postsynaptic density protein PSD‐95. PMCA2a also did not colocalize with glutamic acid decarboxylase‐65, a marker of GABA‐ergic terminals, although it did localize to a small extent with parvalbumin‐positive presumed inhibitory terminals. Pharmacological inhibition of PMCA increased the frequency but not the amplitude of mEPSCs with little effect on mIPSCs or paired‐pulse depression of evoked IPSCs. However, inhibition of PMCA activity did enhance the amplitude and slowed the recovery of paired‐pulse facilitation (PPF) of evoked EPSCs. These results indicated that fast PMCA2a‐mediated clearance of [Ca2+]i from presynaptic excitatory terminals regulated excitatory synaptic transmission within hippocampal CA3.
Load Sharing of Worm Gear With a Plastic Wheel
Authors: Hiltcher Yann , Guingand Michèle , de Vaujany Jean-Pierre
Published: December 2006

The material of the wheel in a worm gear has to be nonrigid due to very high sliding velocity. Such gears are currently made of plastic in the case of a small module. The present paper describes an original method for studying the quasi-static loaded behavior of a worm gear, with a steel worm and a nylon wheel. Plastics are viscoelastic materials and do not obey Hooke’s law. This paper describes an elaborated method that is a generalization of Kelvin’s model. The computation also uses experimental tests to obtain data relating to the plastic. The computation of the load sharing is described and uses the equation of displacement compatibility. The history of previous deformation and the effect of the nylon’s structural damping are taken into account. At a given constant temperature, the load sharing, meshing stiffness, and loaded transmission error depend on the driving torque and time, that is to say speed of rotation.
Calculation of Tooth Bending Strength and Surface Durability of High Transverse Contact Ratio Spur and Helical Gear Drives
Authors: Pedrero José I. , Vallejo Izaskun I. , Pleguezuelos Miguel
Published: December 2006

Calculation methods of spur and helical gear drives with a transverse contact ratio higher than 2, accurate enough for preliminary designs or standardization purposes, are not available in technical literature. If the load is assumed to be uniformly distributed along the line of contact, simple equations given by the linear theory of elasticity and the Hertzian contact model are not in good agreement with experimental results. However, these simple equations may work quite accurately with a more realistic model of load distribution accounting the changing rigidity of the pair of teeth along the path of contact. In this paper a nonuniform model of load distribution along the line of contact, obtained from the minimum elastic potential criterion, has been considered for stress calculation of spur and helical gear drives with transverse contact ratio between 2 and 2.5. The determinant load conditions have been calculated and the nominal contact stress and the nominal tooth-root stress have been computed.
A Compliant Transmission Mechanism With Intermittent Contacts for Cycle-Doubling
Authors: Mankame Nilesh D. , Ananthasuresh G. K.
Published: December 2006

A novel compliant transmission mechanism that doubles the frequency of a cyclic input is presented in this paper. The compliant cycle-doubler is a contact-aided compliant mechanism that uses intermittent contact between itself and a rigid surface. The conceptual design for the cycle-doubler was obtained using topology optimization in our earlier work. In this paper, a detailed design procedure is presented for developing the topology solution into a functional prototype. The conceptual design obtained from the topology solution did not account for the effects of large displacements, friction, and manufacturing-induced features such as fillet radii. Detailed nonlinear finite element analyses and experimental results from quasi-static tests on a macro-scale prototype are used in this paper to understand the influence of the above factors and to guide the design of the functional prototype. Although the conceptual design is based on the assumption of quasi-static operation, the modified design is shown to work well in a dynamic setting for low operating frequencies via finite element simulations. The cycle-doubler design is a monolithic elastic body that can be manufactured from a variety of materials and over a range of length scales. This makes the design scalable and thus adaptable to a wide range of operating frequencies. Explicit dynamic nonlinear finite element simulations are used to verify the functionality of the design at two different length scales: macro (device footprint of a square of 170mm side) at an input frequency of 7.8Hz; and meso (device footprint of a square of 3.78mm side) at an input frequency of 1kHz.
A Clathrate Reservoir Hypothesis for Enceladus' South Polar Plume
Authors: Kieffer Susan W. , Lu Xinli , Bethke Craig M. , Spencer John R. , Marshak Stephen , Navrotsky Alexandra
Published: December 2006

We hypothesize that active tectonic processes in the south polar terrain of Enceladus, the 500-kilometer-diameter moon of Saturn, are creating fractures that cause degassing of a clathrate reservoir to produce the plume documented by the instruments on the Cassini spacecraft. Advection of gas and ice transports energy, supplied at depth as latent heat of clathrate decomposition, to shallower levels, where it reappears as latent heat of condensation of ice. The plume itself, which has a discharge rate comparable to Old Faithful Geyser in Yellowstone National Park, probably represents small leaks from this massive advective system.
Response to Comment on "Early Domesticated Fig in the Jordan Valley"
Authors: Kislev Mordechai E. , Hartmann Anat , Bar-Yosef Ofer
Published: December 2006

We suggest that parthenocarpic or fertile fig branches were planted along with staples like wild barley in the early Neolithic villages of Gilgal and Netiv Hagdud. In contrast to the repeated sowing of wild barley, we argue that planting branches of selected fig trees constitutes a form of domestication. The simplicity of fig tree propagation likely contributed to its domestication before cereal crops.
PROJECTED ENTANGLED STATES: PROPERTIES AND APPLICATIONS
Authors: VERSTRAETE F. , WOLF M. , PÉREZ-GARCÍA D. , CIRAC J. I.
Published: December 2006

We present a new characterization of quantum states, what we call Projected Entangled-Pair States (PEPS). This characterization is based on constructing pairs of maximally entangled states in a Hilbert space of dimension D2, and then projecting those states in subspaces of dimension d. In one dimension, one recovers the familiar matrix product states, whereas in higher dimensions this procedure gives rise to other interesting states. We have used this new parametrization to construct numerical algorithms to simulate the ground state properties and dynamics of certain quantum-many body systems in two dimensions.
QUANTUM MONTE CARLO STUDY OF THE GROUND-STATE PROPERTIES OF A FERMI GAS IN THE BCS-BEC CROSSOVER
Authors: GIORGINI S. , ASTRAKHARCHIK G. E. , BORONAT J. , CASULLERAS J.
Published: December 2006

The ground-state properties of a two-component Fermi gas with attractive short-range interactions are calculated using the fixed-node diffusion Monte Carlo method. The interaction strength is varied over a wide range by tuning the value a of the s-wave scattering length of the two-body potential. We calculate the energy per particle, the one- and two-body density matrix as a function of the interaction strength. Results for the momentum distribution of the atoms, as obtained from the Fourier transform of the one-body density matrix, are reported as a function of the interaction strength. Off-diagonal long-range order in the system is investigated through the asymptotic behavior of the two-body density matrix. The condensate fraction of pairs is calculated in the unitary limit and on both sides of the BCS-BEC crossover.
COLLAPSE OF K-Rb FERMI-BOSE MIXTURES IN OPTICAL LATTICES
Authors: JEZEK D. M. , CATALDO H. M.
Published: December 2006

We study a confined mixture of Rb and K atoms in a one dimensional optical lattice, at low temperature, in the quanta1 degeneracy regime. This mixture exhibits an attractive boson-fermion interaction, and thus above certain values of the number of particles the mixture collapses. We investigate, in the mean-field approximation, the curve for which this phenomenon occurs, in the space of number of particles of both species. This is done for different types of optical lattices.
BOSE - EINSTEIN CONDENSATE SUPERFLUID - MOTT INSULATOR TRANSITION IN AN OPTICAL LATTICE
Authors: REY ANA M. , CALZETTA ESTEBAN A. , HU BEI-LOK
Published: December 2006

We present in this paper an analytical model for a cold bosonic gas on an optical lattice (with densities of the order of 1 particle per site) targeting the critical regime of the Bose - Einstein Condensate superfluid - Mott insulator transition.
THEORY OF ELECTRON SPECTROSCOPIES IN STRONGLY CORRELATED SEMICONDUCTOR QUANTUM DOTS
Authors: RONTANI MASSIMO
Published: December 2006

Quantum dots may display fascinating features of strong correlation such as finite-size Wigner crystallization. We here review a few electron spectroscopies and predict that both inelastic light scattering and tunneling imaging experiments are able to capture clear signatures of crystallization.
THE NUMBER SELF-CONSISTENT RENORMALIZED RANDOM PHASE APPROXIMATION
Authors: MARIANO A.
Published: December 2006

RPA and its quasiparticle generalization (QRPA) have been widely used to study electromagnetic transitions and beta decays in medium and heavy nuclei, being the pn-QRPA charge exchange mode extensively employed in the description of single and double beta decays in vibrational nuclei. However develops a collapse, i.e. it presents imaginary eigen-values for strengths beyond a critical value of the force. Extensions called renormalized QRPA (RQRPA) do not develop any collapse going beyond the simplest quasiboson approximation, however they present several drawbacks which will be analyzed.
ON THE LEARNING OF SYSTEM CALL ATTRIBUTES FOR HOST-BASED ANOMALY DETECTION
Authors: TANDON GAURAV , CHAN PHILIP K.
Published: December 2006

Traditional host-based anomaly detection systems model normal behavior of applications by analyzing system call sequences. The current sequence is then examined (using the model) for anomalous behavior, which could correspond to attacks. Though these techniques have been shown to be quite effective, a key element is missing – the inclusion and utilization of the system call arguments. Recent research shows that sequence-based systems are prone to evasion. We propose an idea of learning different representations for system call arguments. Results indicate that this information can be effectively used for detecting more attacks than traditional sequence-based techniques, with reasonable storage and computational overhead.
STRUCTURE DISCOVERY IN SEQUENTIALLY-CONNECTED DATA STREAMS
Authors: COBLE JEFFREY , COOK DIANE J. , HOLDER LAWRENCE B.
Published: December 2006

Historically, data mining research has been focused on discovering sets of attributes that discriminate data entities into classes or association rules between attributes. In contrast, we are working to develop data mining techniques to discover patterns consisting of complex relationships between entities. Our research is particularly applicable to domains in which the data is event driven, such as counter-terrorism intelligence analysis. In this paper we describe an algorithm designed to operate over relational data received from a continuous stream. Our approach includes a mechanism for summarizing discoveries from previous data increments so that the globally best patterns can be computed by examining only the new data increment. We then describe a method by which relational dependencies that span across temporal increment boundaries can be efficiently resolved so that additional pattern instances, which do not reside entirely in a single data increment, can be discovered. We also describe a method for change detection using a measure of central tendency designed for graph data. We contrast two formulations of the change detection process and demonstrate the ability to identify salient changes along meaningful dimensions and recognize trends in a relational data stream.
INFINITE-HORIZON OPTIMAL CONTROL BASED ON CONTINUOUS-TIME CONTINUOUS-STATE HOPFIELD NEURAL NETWORKS
Authors: LI MING-AI , YU NAI-GONG , QIAO JUN-FEI , RUAN XIAO-GANG
Published: December 2006

An optimal control method based on continuous-time continuous-state Hopfield neural network (CTCSHNN) is proposed for time-varying multivariable systems. The equivalence is built theoretically between receding-horizon linear quadratic (LQ) performance index and energy function of CTCSHNN, and the CTCSHNN is constructed to solve the above LQ optimization control problems. Moreover, the rolling optimization strategy is adopted to form closed-loop control structure that includes CTCSHNN so, the dynamic infinite-horizon optimization control is realized for multivariable time-varying systems. As an example, a second order time-varying system is simulated. Simulation results show the effectiveness and feasibility of the proposed method.
GENETIC REGULATION OF CARDIOGENESIS AND CONGENITAL HEART DISEASE
Authors: Srivastava Deepak
Published: December 2006

Developmental heart disorders are the most common of all human birth defects and occur in nearly one percent of the population. Survivors of congenital heart malformations are an increasing population, and it is becoming clear that genetic mutations that cause developmental anomalies may result in cardiac dysfunction later in life. This review highlights the progress in understanding the underlying molecular basis for cardiac formation and how disruption of the intricate steps of cardiogenesis can lead to congenital heart defects. The lessons learned from examining the early steps of heart formation are essential for informing the prevention of malformations and their long-term consequences, as well as for approaches to guide stem cells into cardiac lineages.
PATHOGENESIS OF NONIMMUNE GLOMERULOPATHIES
Authors: Kwoh Christopher , Shannon M. Brendan , Miner Jeffrey H. , Shaw Andrey
Published: December 2006

Nonimmune glomerulopathies are an area of significant research. This review discusses the development of focal segmental glomerulosclerosis, with particular attention to the role of the podocyte in the initiation of glomerulosclerosis and the contribution to glomerulosclerosis from capillary hypertension and soluble factors such as transforming growth factor beta, platelet-derived growth factor, vascular endothelial growth factor, and angiotensin. The effects of these factors on endothelial and mesangial cells are also discussed. In addition, we review our current understanding of the slit diaphragm (a specialized cell junction found in the kidney), slit diaphragm–associated proteins (including nephrin, podocin, α-actinin-4, CD2-associated protein, and transient receptor potential channel 6), and the role of these proteins in glomerular disease. We also discuss the most recent research on the pathogenesis of collapsing glomerulosclerosis, human immunodeficiency virus associated nephropathy, Denys-Drash, diabetic nephropathy, Alport syndrome, and other diseases related to the interaction between the podocyte and the glomerular basement membrane.
TUMOR STROMA AND REGULATION OF CANCER DEVELOPMENT
Authors: Tlsty Thea D. , Coussens Lisa M.
Published: December 2006

In the past 25 years, a majority of cancer studies have focused on examining functional consequences of activating and/or inactivating mutations in critical genes implicated in cell cycle control. These studies have taught us a great deal about the functions of oncogenes and tumor suppressor genes and the signaling pathways regulating cell proliferation and/or cell death. However, such studies have largely ignored the fact that cancers are heterogeneous cellular entities whose growth is dependent upon reciprocal interactions between genetically altered “initiated” cells and the dynamic microenvironment in which they live. This review highlights the aspects of cancer development that, like organogenesis during embryonic development and tissue repair in adult mammals, are regulated by interactions between epithelial cells, activated stromal cells, and soluble and insoluble components of the extracellular matrix.
Health Impact Assessment: A Tool to Help Policy Makers Understand Health Beyond Health Care
Authors: Cole Brian L. , Fielding Jonathan E.
Published: December 2006

Health impact assessment (HIA)—a combination of methods to examine formally the potential health effects of a proposed policy, program, or project—has received considerable interest over the past decade internationally as a practical mechanism for collaborating with other sectors to address the environmental determinants of health and to achieve more effectively the goals of population health promotion. Demand for HIA in the United States seems to be growing. This review outlines the common principles and methodologies of HIA and compares different approaches to HIA. Lessons learned from the related field of environmental impact assessment and from experience with HIA in other countries are examined. Possible avenues for advancing both the field and the broader goals of population health promotion are outlined.
Development of a new mouse model of acute pancreatitis induced by administration of l-arginine
Authors: Dawra Rajinder , Sharif Rifat , Phillips Phoebe , Dudeja Vikas , Dhaulakhandi Dhara , Saluja Ashok K.
Published: December 2006

The pathogenesis of acute pancreatitis is not fully understood. Experimental animal models that mimic human disease are essential to better understand the pathophysiology of the disease and to evaluate potential therapeutic agents. Given that the mouse genome is known completely and that a large number of strains with various genetic deletions are available, it is advantageous to have multiple reliable mouse models of acute pancreatitis. Presently, there is only one predominant model of acute pancreatitis in mice, in which hyperstimulatory doses of cholecystokinin or its analog caerulein are administered. Therefore, the aim of this study was to develop another mouse model of acute pancreatitis. In this study, C57BL/6 mice were injected intraperitoneally with l-arginine in two doses of 4 g/kg each, 1 h apart. Serum amylase, myeloperoxidase, and histopathology were examined at varying time points after injection to assess injury to the pancreas and lung. We found that injection of l-arginine was followed by significant increases in plasma amylase and pancreatic myeloperoxidase accompanied by marked histopathological changes. The injury to the pancreas was slow to develop and peaked at 72 h. Subsequent to peak injury, the damaged areas contained collagen fibers as assessed by increased Sirius red staining. In contrast, d-arginine or other amino acids did not cause injury to the pancreas. In addition, acute inflammation in the pancreas was associated with lung injury. Our results indicate that administration of l-arginine to mice results in severe acute pancreatitis. This model should help in elucidating the pathophysiology of pancreatitis.