bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of tumor removal on tinnitus in patients with vestibular schwannoma
Authors: Kameda Katsuharu , Shono Tadahisa , Hashiguchi Kimiaki , Yoshida Fumiaki , Sasaki Tomio
Published: May 2009

Object

Tinnitus is one of the most common symptoms in patients with vestibular schwannomas (VSs), but the effect of surgery on this symptom has not been fully evaluated. The aim of this study was to define the effect on tinnitus of tumor removal, cochlear nerve resection, and useful hearing preservation in patients with VSs.

Methods

The authors retrospectively analyzed the status of tinnitus before and after surgery in 242 patients with unilateral VSs who underwent surgery via the retrosigmoid lateral suboccipital approach.

Results

Of 242 patients, 171 (70.7%) complained of tinnitus before surgery; the symptom disappeared in 25.2%, improved in 33.3%, remained unchanged in 31.6%, and worsened in 9.9% of these cases after tumor removal. In the 171 patients with preoperative tinnitus, the cochlear nerve was resected in 85 (49.7%) and preserved in 86 (50.3%), but there was no significant difference in the incidence of postoperative tinnitus between these 2 groups (p = 0.293). In the 71 patients without preoperative tinnitus, the symptom developed postoperatively in 6 cases (8.5%). Among those without preoperative tinnitus, the cochlear nerve was resected in 45 cases (63.4%) and tinnitus appeared postoperatively in 3 (6.7%). The authors also analyzed the association between postoperative tinnitus and useful hearing preservation, but could not find any statistically significant association between the 2 factors (p = 0.153).

Conclusions

Tumor removal via the retrosigmoid lateral suboccipital approach may provide some chance for improvement of tinnitus in patients with VSs; however, neither cochlear nerve resection nor useful hearing preservation affects the postoperative development of tinnitus.
First intraoperative, shared-resource, ultrahigh-field 3-Tesla magnetic resonance imaging system and its application in low-grade glioma resection
Authors: Pamir M. Necmettin , Özduman Koray , Dinçer Alp , Yildiz Erdem , Peker Selçuk , Özek M. Memet
Published: May 2009

Object

The authors describe the first shared-resource, 3-T intraoperative MR (ioMR) imaging system and analyze its impact on low-grade glioma (LGG) resection with an emphasis on the use of intraoperative proton MR spectroscopy.

Methods

The Acibadem University ioMR imaging facility houses a 3-T Siemens Trio system and consists of interconnected but independent MR imaging and surgical suites. Neurosurgery is performed using regular ferromagnetic equipment, and a patient can be transferred to the ioMR imaging system within 1.5 minutes by using a floating table. The ioMR imaging protocol takes < 10 minutes including the transfer, and the authors obtain very high–resolution T2-weighted MR images without the use of intravenous contrast. Functional sequences are performed when needed. A new 5-pin headrest–head coil combination and floating transfer table were specifically designed for this system.

Results

Since the facility became operational in June 2004, 56 LGG resections have been performed using ioMR imaging, and > 19,000 outpatient MR imaging procedures have been conducted. First-look MR imaging studies led to further resection attempts in 37.5% of cases as well as a 32.3% increase in the number of gross-total resections. Intraoperative ultrasonography detected 16% of the tumor remnants. Intraoperative proton MR spectroscopy and diffusion weighted MR imaging were used to differentiate residual tumor tissue from peritumoral parenchymal changes. Functional and diffusion tensor MR imaging sequences were used both pre- and postoperatively but not intraoperatively. No infections or other procedure-related complications were encountered.

Conclusions

This novel, shared-resource, ultrahigh-field, 3-T ioMR imaging system is a cost-effective means of affording a highly capable ioMR imaging system and increases the efficiency of LGG resections.
Seed tolerance to predation: Evidence from the toxic seeds of the buckeye tree (Aesculus californica; Sapindaceae)
Authors: Mendoza Eduardo , Dirzo Rodolfo
Published: May 2009

Tolerance, the capacity of plants to withstand attack by animals, as opposed to resistance, has been poorly examined in the context of seed predation. We investigated the role that the seed mass of the large‐seeded endemic tree Aesculus californica plays as a tolerance trait to rodent attack by comparing, under greenhouse conditions, patterns of germination, and subsequent seedling growth, of seeds with a wide range of natural damage. Germination percentage was reduced by 50% and time to germination by 64% in attacked compared to intact seeds, and germination probability was negatively correlated with damage. Seedlings that emerged from intact seeds were taller and bore more leaves than those from damaged seeds. This species’ large seed mass favors tolerance to damage because heavily damaged seeds are able to germinate and produce seedlings. This finding is significant given that seeds of this species are known to contain chemical compounds toxic to vertebrates, a resistance trait. We posit that this combination of tolerance and resistance traits might be a particularly effective antipredation strategy when seeds are exposed to a variety of vertebrate predators.
Floral organogenesis and the developmental basis for pollinator deception in the asiatic dayflower, Commelina communis (Commelinaceae)
Authors: Hardy Christopher R. , Sloat Lindsey L. , Faden Robert B.
Published: May 2009

The upper half of flowers in Commelina communis deceptively lures potential pollinators with its showy petals and staminodes on the false promise of abundant pollen. This paper presents evidence that staminodization in the upper half is associated with a severe retardation of the entire upper floral hemisphere early in development. Possible consequences of this developmental retardation are seen also in the gynoecium, where the upper carpel of the three‐carpellate ovary is underdeveloped and sterile at maturity. Only late in development do the upper petals and staminodes expand and acquire pigments necessary for their attractive function. We surmise that retardations of this severity are unlikely to be found for functionally fertile organs such as stamens and ovule‐producing carpels, because key preparatory events preceding sporogenesis might otherwise be disrupted. Such differential growth about the floral apex resembles that known in some eudicots to be regulated by the TCP gene family; thus, future molecular developmental studies in Commelina may help to extend our understanding of the evolutionary genetics of floral monosymmetry to monocots.
Human performance variation analysis: A process for human performance problem solving
Authors: Rademeyer Anerie , Du Plessis Yvonne , Kepner Charles H.
Published: May 2009

Problem-solving ability is a much sought-after trait in executives, especially if it includes the ability to solve human performance problems. This paper proposes a systematic root cause analysis process that effectively and consistently uncovers the root causes of human performance problems and controls the causes in a way that prevents the problems from recurring. Applying action research the study brings into being a Human Performance Variation Analysis (HPVA) process, which consists of three phases: (1) performance variation assessment, (2) performance variation analysis, and (3) performance variation resolution. The HPVA provides much-needed capability in solving human performance problems in organisations.
Peroxisome Proliferator‐Activated Receptor‐g Agonist Treatment Increases Septation and Angiogenesis and Decreases Airway Hyperresponsiveness in a Model of Experimental Neonatal Chronic Lung Disease
Authors: Takeda K. , Okamoto M. , de Langhe S. , Dill E. , Armstrong M. , Reisdorf N. , Irwin D. , Koster M. , Wilder J. , Stenmark K.R. , West J. , Klemm D. , Gelfand E.W. , Nozik‐Grayck E. , Majka S.M.
Published: May 2009

Chronic lung disease (CLD) affects premature newborns requiring supplemental oxygen and results in impaired lung development and subsequent airway hyperreactivity. We hypothesized that the maintenance of peroxisome proliferator‐activated receptor gamma (PPARγ) signaling is important for normal lung morphogenesis and treatment with PPARγ agonists could protect against CLD and airway hyperreactivity (AHR) following chronic hyperoxic exposure. This was tested in an established hyperoxic murine model of experimental CLD. Newborn mice and mothers were exposed to room air (RA) or moderate hyperoxia (70% oxygen) for 10 days and fed a standard diet or chow impregnated with the PPARγ agonist rosiglitazone (ROSI) for the duration of study. Following hyperoxic exposure (HE) animals were returned to RA until postnatal day (P) 13 or P41. The accumulation of ROSI in neonatal and adult tissue was confirmed by mass spectrometry. Analyses of body weight and lung histology were performed on P13 and P41 to localize and quantitate PPARγ expression, determine alveolar and microvessel density, proliferation and alpha‐smooth muscle actin (α‐SMA) levels as a measure of myofibroblast differentiation. Microarray analyses were conducted on P13 to examine transcriptional changes in whole lung. Pulmonary function and airway responsiveness were analyzed at P55. ROSI treatment during HE preserved septation and vascular density. Key array results revealed ontogeny groups differentially affected by hyperoxia including cell cycle, angiogenesis, matrix, and muscle differentiation/contraction. These results were further confirmed by histological evaluation of myofibroblast and collagen accumulation. Late AHR to methacholine was present in mice following HE and attenuated with ROSI treatment. These findings suggest that rosiglitazone maintains downstream PPARγ effects and may be beneficial in the prevention of severe CLD with AHR. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.
Mammalian NDR/LATS protein kinases in hippo tumor suppressor signaling
Authors: Hergovich Alexander , Hemmings Brian A.
Published: May 2009

The NDR/LATS family of kinases is a subgroup of the AGC group of protein kinases and is conserved from lower eukaryotes to humans. Like other AGC kinases, NDR/LATS kinases require phosphorylation of conserved Ser/Thr residues for activation. On the one hand, binding of the coactivator MOB to NDR/LATS allows autophosphorylation. On the other hand, MST kinases directly phosphorylate NDR/LATS kinases. In addition to our understanding of the molecular activation mechanisms, recent studies have shown that LATS kinases play a central role in Hippo/SWH (Salvador/Warts/Hippo) tumor suppressor pathways, which coordinate cell proliferation and apoptosis by regulating proto‐oncogenes, such as YAP and TAZ. In this review, we summarize current knowledge of Merlin/MST/SAV/MOB/LATS/NDR/YAP/TAZ networks (also termed mammalian Hippo signaling) and their roles in mammalian cellular transformation. © 2009 International Union of Biochemistry and Molecular Biology, Inc.
Carboplatin‐based primary chemotherapy for infants and young children with CNS tumors
Authors: Fouladi Maryam , Gururangan Sri , Moghrabi Albert , Phillips Peter , Gronewold Lindsey , Wallace Dana , Sanford Robert A. , Gajjar Amar , Kun Larry E. , Heideman Richard
Published: May 2009

BACKGROUND:

A carboplatin‐based chemotherapy regimen was used as primary postoperative therapy in infants with central nervous system (CNS) tumors to limit renal and ototoxicity and to target systemic exposure.

METHODS:

Fifty‐three patients aged <age 3 years with embryonal CNS tumor medulloblastoma (n = 20), ependymoma (EP, n = 21), choroid plexus carcinoma (CPCA, n = 5), and primitive embryonal neoplasms including atypical teratoid rhabdoid tumors (n = 7) were treated with cyclophosphamide, etoposide, and carboplatin. Radiation therapy was used only for residual disease at the end of chemotherapy or disease progression.

RESULTS:

The response rate after 2 cycles of chemotherapy was 34% (complete response, 13.8%; partial response, 20.7%). Myelosuppression was the dominant toxicity; 2 patients had toxic deaths related to thrombocytopenia with trauma. The 5‐year overall survival (OS) was 49% ± 7%, and the progression‐free survival (PFS) was 31% ± 7%, with a median follow‐up of 11.4 years (range, 5.2‐15.0 years). For medulloblastoma, the 5‐year PFS was 26% ± 9%; for EP it was 33% ± 10%; for CPCA it was 80% ± 18%; and for primitive neuroectodermal and atypical teratoid rhabdoid tumors it was 0%. Localized EP patients with gross total resection who did not undergo radiotherapy had a 5‐year PFS of 57% ± 17% and OS of 71% ± 16%. Two patients developed late second malignancies; 1 was associated with germline p53 mutation.

CONCLUSIONS:

The results confirm that carboplatin has similar activity to cisplatin in otherwise similar regimens. Five‐year survival data are comparable to those reported in other recent studies, including high‐dose chemotherapy studies. Of note is the marked activity in CPCA and gross totally resected EP. Cancer 2009. © 2009 American Cancer Society.
Does hormone treatment added to radiotherapy improve outcome in locally advanced prostate cancer?
Authors: Bria Emilio , Cuppone Federica , Giannarelli Diana , Milella Michele , Ruggeri Enzo Maria , Sperduti Isabella , Pinnarò Paola , Terzoli Edmondo , Cognetti Francesco , Carlini Paolo
Published: May 2009

BACKGROUND:

To quantify the magnitude of benefit of the addition of hormone treatment (HT) to exclusive radiotherapy for locally advanced prostate cancer, a literature‐based meta‐analysis was conducted.

METHODS:

Event‐based relative risks (RR) with 95% confidence intervals (CIs) were derived through a random‐effect model. Differences in primary (biochemical failure and clinical progression‐free survival) and secondary outcomes (cancer‐specific survival, overall survival [OS], recurrence patterns, and toxicity) were explored. Absolute differences and numbers of patients needed to treat (NNT) were calculated. A heterogeneity test, a metaregression analysis with clinical predictors of outcome, and a correlation analysis for surrogate endpoints were also performed.

RESULTS:

Seven trials (4387 patients) were gathered. Hormone suppression significantly decreased both biochemical failure (RR, 0.76; 95% CI, 0.70‐0.82; P < .0001) and clinical progression‐free survival (RR, 0.81; 95% CI 0.71‐0.93; P = .002), with absolute differences of 10% and 7.7%, respectively, which translates into 10 and 13 NNT. cancer‐specific survival (RR, 0.76; 95% CI, 0.69‐0.83; P < .0001) and OS (RR, 0.86; 95% CI, 0.80‐0.93; P < .0001) were also significantly improved by the addition of HT, without significant heterogeneity, with absolute differences of 5.5% and 4.9%, respectively, which translates into 18 and 20 NNT. Local and distant relapse were significantly decreased by HT, by 36% and 28%, respectively, and no significant differences in toxicity were found. Primary and secondary efficacy outcomes were significantly correlated.

CONCLUSIONS:

Hormone suppression plus radiotherapy significantly decreases recurrence and mortality of patients with localized prostate cancer, without affecting toxicity. Cancer 2009. © 2009 American Cancer Society.
Perineural invasion in cancer
Authors: Liebig Catherine , Ayala Gustavo , Wilks Jonathan A. , Berger David H. , Albo Daniel
Published: May 2009

Perineural invasion (PNI) is the process of neoplastic invasion of nerves and is an under‐recognized route of metastatic spread. It is emerging as an important pathologic feature of many malignancies, including those of the pancreas, colon and rectum, prostate, head and neck, biliary tract, and stomach. For many of these malignancies, PNI is a marker of poor outcome and a harbinger of decreased survival. PNI is a distinct pathologic entity that can be observed in the absence of lymphatic or vascular invasion. It can be a source of distant tumor spread well beyond the extent of any local invasion; and, for some tumors, PNI may be the sole route of metastatic spread. Despite increasing recognition of this metastatic process, there has been little progress in the understanding of molecular mechanisms behind PNI and, to date, no targeted treatment modalities aimed at this pathologic entity. The objectives of this review were to lay out a clear definition of PNI to highlight its significance in those malignancies in which it has been studied best. The authors also summarized current theories on the molecular mediators and pathogenesis of PNI and introduced current research models that are leading to advancements in the understanding of this metastatic process. Cancer 2009. © 2009 American Cancer Society.
Human cytochrome P450 2E1 and sulfotransferase 1A1 coexpressed in Chinese hamster V79 cells enhance spontaneous mutagenesis
Authors: Liu Yungang , Glatt Hansruedi
Published: May 2009

Genetic engineering of target cells for investigating the genotoxicity associated with specific xenobiotic‐metabolizing enzymes is useful for elucidating metabolic activation and inactivation processes. We constructed a V79‐derived cell line expressing both human cytochrome P450 (CYP) 2E1 and human sulfotransferase (SULT) 1A1. We previously reported that this cell line (V79‐hCYP2E1‐hSULT1A1) efficiently activates various important pro‐genotoxicants. Here we present data on the expression level and stability of the heterologous enzymes, measured by immunoblotting, enzyme activities, and mutagenic responses to CYP2E1‐ and SULT1A1‐dependent promutagens. Unexpectedly, these cells demonstrated greatly elevated spontaneous gene mutation frequencies (determined at the Hprt locus), and elevated frequencies of sister chromatid exchange, as compared with control V79 cells and V79‐derived lines engineered for other enzymes. Therefore, V79‐hCYP2E1‐hSULT1A1 cells require regular cleansing in aminopterin‐containing medium when used for Hprt gene mutation assays. In a 4‐week time course without such selection, V79‐hCYP2E1‐hSULT1A1 demonstrated a progressive increase in the spontaneous mutant frequency from 2.9 to 155 × 10−6. This phenomenon was moderately, strongly, and completely prohibited in the presence of CYP2E1 inhibitor 1‐aminobenzotriazole, SULT1A1 inhibitor pentachlorophenol and both in combination, respectively. This protection indicates that the enhanced spontaneous mutagenicity involves the activity of the expressed enzymes rather than being caused by an accidental genetic alteration that might have occurred during transfection. We postulate that human CYP2E1 and SULT1A1 activate an endogenous cellular molecule or a medium component to become mutagenic. It will be challenging to identify this compound and to see whether it is involved in spontaneous mutagenesis and carcinogenesis in vivo. Environ. Mol. Mutagen., 2010. © 2009 Wiley‐Liss, Inc.
Patterns of failure among patients with squamous cell carcinoma of the head and neck who obtain a complete response to chemoradiotherapy
Authors: Yovino Susannah , Settle Kathleen , Taylor Rodney , Wolf Jeffrey , Kwok Young , Cullen Kevin , Ord Robert , Zimrin Ann , Strome Scott , Suntharalingam Mohan
Published: May 2009

Background.

The role of adjuvant neck dissection in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN) who obtain complete clinical and radiologic response following definitive chemoradiation treatment is controversial.

Methods.

Patterns of failure among 120 patients with locally advanced SCCHN, all with node‐positive disease, treated with concurrent chemoradiation, were analyzed.

Results.

Ninety‐one of the patients achieved a complete response and were observed without undergoing neck dissection. Isolated failure in the neck occurred in 2 patients. The most common site of failure was metastatic disease (17 patients). Six patients had recurrence at the primary only, and 1 experienced failure in the neck and at the primary. Partial responders with resectable disease underwent neck dissection following chemoradiation. This group had worse local control and overall survival compared with complete responders.

Conclusions.

We recommend observation after definitive chemoradiation for complete responders. Further research is needed to improve outcomes among partial responders. © 2009 Wiley Periodicals, Inc. Head Neck, 2010
Divergent Adaptation of Hepatitis C Virus Genotypes 1 and 3 to Human Leukocyte Antigen–Restricted Immune Pressure†
Authors: Rauch Andri , James Ian , Pfafferott Katja , Nolan David , Klenerman Paul , Cheng Wendy , Mollison Lindsay , McCaughan Geoff , Shackel Nick , Jeffrey Gary P. , Baker Ross , Freitas Elizabeth , Humphreys Isla , Furrer Hansjakob , Günthard Huldrych F. , Hirschel Bernard , Mallal Simon , John Mina , Lucas Michaela , Barnes Eleanor , Gaudieri Silvana
Published: May 2009

Many hepatitis C virus (HCV) infections worldwide are with the genotype 1 and 3 strains of the virus. Cellular immune responses are known to be important in the containment of HCV genotype 1 infection, and many genotype 1 T cell targets (epitopes) that are presented by host human leukocyte antigens (HLAs) have been identified. In contrast, there is almost no information known about the equivalent responses to genotype 3. Immune escape mechanisms used by HCV include the evolution of viral polymorphisms (adaptations) that abrogate this host–viral interaction. Evidence of HCV adaptation to HLA-restricted immune pressure on HCV can be observed at the population level as viral polymorphisms associated with specific HLA types. To evaluate the escape patterns of HCV genotypes 1 and 3, we assessed the associations between viral polymorphisms and specific HLA types from 187 individuals with genotype 1a and 136 individuals with genotype 3a infection. We identified 51 HLA-associated viral polymorphisms (32 for genotype 1a and 19 for genotype 3a). Of these putative viral adaptation sites, six fell within previously published epitopes. Only two HLA-associated viral polymorphisms were common to both genotypes. In the remaining sites with HLA-associated polymorphisms, there was either complete conservation or no significant HLA association with viral polymorphism in the alternative genotype. This study also highlights the diverse mechanisms by which viral evasion of immune responses may be achieved and the role of genotype variation in these processes.

Conclusion:

There is little overlap in HLA-associated polymorphisms in the nonstructural proteins of HCV for the two genotypes, implying differences in the cellular immune pressures acting on these viruses and different escape profiles. These findings have implications for future therapeutic strategies to combat HCV infection, including vaccine design. (Hepatology 2009.)
Influence of selenium dose on mercury distribution and retention in suckling rats
Authors: Orct Tatjana , Lazarus Maja , Jurasović Jasna , Blanuša Maja , Piasek Martina , Kostial Krista
Published: May 2009

It is well known that metal–metal interactions in the body are age‐dependent. We studied the influence of increasing selenium (Se) doses on mercury (Hg) distribution and retention in the postnatal period in Hg‐exposed suckling rats. Seven‐day‐old Wistar pups were pretreated with three different oral doses of Se as sodium selenite (6.45, 12.9 and 19.4 µmol Se kg−1 b.w.) over 3 days. This was followed by simultaneous Se (as sodium selenite) and Hg (as mercury chloride) oral administration over 4 days. The molar ratio between Se and Hg given to pups was 1:1, 2:1 and 3:1, respectively. Mercury and Se were measured in brain, kidneys, liver, plasma, erythrocytes and urine of pups on the day after the last administration by atomic absorption spectrometry. Results showed that in all samples Se concentrations rose almost proportionally to the dose of Se given to pups. Mercury concentration in organs, plasma and urine decreased with higher oral doses of Se. However, Hg concentration in erythrocytes increased with increasing Se dose. There was evidently a redistribution of Hg from plasma to erythrocytes at higher ratio of Se:Hg. Approximately equimolar doses of Se and Hg are necessary to produce maximum uptake of Hg by plasma and liver and minimum retention of Hg in the kidney and erythrocytes. Copyright © 2009 John Wiley & Sons, Ltd.
Cytocompatibility of high strength non‐oxide ceramics
Authors: Cappi Benjamin , Neuss Sabine , Salber Jochen , Telle Rainer , Knüchel Ruth , Fischer Horst
Published: May 2009

Oxide ceramic materials like alumina (Al2O3) and zirconia (ZrO2) are frequently used for medical applications like implants and prostheses because of their excellent biocompatibility and high wear resistance. Unfortunately, oxide ceramics cannot be used for minimal invasive thin‐walled implants like resurfacing hip prostheses because of their limited strength. The hypothesis ofthis study is that non‐oxide ceramics like silicon nitride (Si3N4) and silicon carbide (SiC)—not previously used in the medical field—are not only high strength and mechanically reliable ceramic materials due to their high amount of covalent bonds, but also exhibit a suitable biocompatibility for use as medical implants and prostheses. Mechanical investigations and cell culture tests with mouse fibroblast cells (L929) and human mesenchymal stem cells (hMSC) were performed on the ceramics. An excellent cytocompatibility was demonstrated by live/dead stainings for both L929 cells and hMSC. HMSC wereable to differentiate towards osteoblasts on all tested ceramics. The determined strength of silicon nitride and silicon carbide was shown as significantly higher than that of oxide ceramics. Our results indicate that the high strength non‐oxide ceramics are material candidates in the future especially for highly loaded, thin‐walled implants like ceramic resurfacing hip prostheses. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Expression of patched‐1 and smoothened in testicular meiotic and post‐meiotic cells
Authors: Morales Carlos R. , Fox Andrew , El‐Alfy Mohamed , Ni Xiaoyan , Argraves W. Scott
Published: May 2009

Desert hedgehog (Dhh) signaling plays an essential role in the normal development of the testis and in the process of spermatogenesis. Little is known about the involvement in spermatogenesis of the prototypic member of the family, Ptc1, which acts to suppress hedgehog signaling through Smoothened (Smo). Here, we have examined the expression of Ptc1, Smo, and Dhh in mouse and rat seminiferous epithelium. Our findings demonstrate that Ptc1 and Smo are expressed by primary spermatocytes and by round and condensing spermatids whereas Dhh is expressed by Sertoli cells. The findings suggest that Sertoli cells coordinate Dhh‐dependent spermatogenesis events via Ptc1 and Smo prior to the first meiotic division and in postmeiotic (haploid) cells, particularly during the first half of spermiogenesis. Microsc. Res. Tech. 2009. © 2009 Wiley‐Liss, Inc.
Measurement of edge verticality of optical recording bits on blu‐ray discs using scanning probe microscopy
Authors: Chen Sy‐Hann , Lin Wen‐Siou , Wang Wen‐Ching
Published: May 2009

This work investigates recording bits on recordable and rewritable blu‐ray discs using atomic force microscopy and conducting atomic force microscopy with high contrast, respectively. The geometric structure of the recording bits is clearly observed in images, which, when coupled with cross‐section analysis, yields precise bit dimensions, and edge horizontal extended length values. The microscopic results are a valuable reference for increasing the recognition rate of digital signals in optical storage media. Furthermore, such a rapid and convenient measuring mode is an indispensable research tool for developing new recording materials and improving formation mechanisms. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.
Conventional and RAFT miniemulsion copolymerizations of butyl methacrylate with fluoromethacrylate and monomer reactivity ratios
Authors: Zhang Qinghua , Wang Qiongyan , Luo Zhenhuan , Zhan Xiaoli , Chen Fengqiu
Published: May 2009

Reversible addition fragmentation chain transfer (RAFT) mediated and conventional miniemulsion copolymerizations of butyl methacrylate (BMA) with fluoromethacrylate (FMA) were carried out at 70°C with potassium persulphate as initiator. The kinetics of the copolymerizations was investigated comparatively. Copolymer compositions at low conversion levels were determined by 1H NMR and FTIR spectra techniques. In the presence of RAFT agent 2‐cyanoprop‐2‐yl dithiobenzoate, the copolymerization of BMA with FMA in miniemulsion was obviously retarded. The copolymerization exhibited typical features of controlled molecular weights and narrow polydispersities. The reactivity ratios were evaluated by Kellen‐Tudos (K‐T) method, which yields the apparent reactivity ratios: rBMA = 0.73 and rFMA = 0.75 in conventional copolymerizations, and rBMA = 0.65 and rFMA = 0.70 in CPDB‐mediated system. The results show that the monomer FMA with a perfluoroalkyl side chain is slightly more reactive than BMA, and the copolymerizations process have a tendency to crosspropagate and to produce a higher FMA content in the copolymers. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Melt processing and rheology of an acrylonitrile copolymer with absorbed carbon dioxide
Authors: Wilding Matthew D. , Baird Donald G.
Published: May 2009

The purpose of this study is to determine under what conditions it is possible to use CO2 to plasticize and, thereby, reduce the viscosity of an acrylonitrile (AN) copolymer in an extrusion process and render it melt processable. To assess whether it was possible to absorb adequate amounts of CO2 in short residence times by injection into a single screw extruder, a slit‐die rheometer was attached to the end of the extrusion system for the purpose of directly assessing the viscosity reduction. A chemorheological analysis was performed on 65 and 85% AN copolymers to establish the temperature at which the 85% material would be as stable as the melt‐processable 65% material at its recommended extrusion temperature. This, coupled with studies correlating the degree of Tg and viscosity reduction with the amount of absorbed CO2, and comparison to previous data obtained in batch processes allowed one to predict conditions for melt extrusion of the 85% AN. Preliminary studies using a pressurized chamber attached to the exit of the die allowed one to assess the conditions under which suppression of foaming is possible. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
High Aldehyde Dehydrogenase Activity: A Novel Functional Marker of Murine Prostate Stem/Progenitor Cells
Authors: Burger Patricia E. , Gupta Rashmi , Xiong Xiaozhong , Ontiveros Christopher S. , Salm Sarah N. , Moscatelli David , Wilson E. Lynette
Published: May 2009

We have shown previously that prostatic stem/progenitor cells can be purified from isolated prostate ducts, based on their high expression of the Sca-1 surface antigen. We now report that high levels of aldehyde dehydrogenase (ALDH) activity are present in a subset of prostate epithelial cells that coexpress a number of antigens found on stem/progenitor cells of other origins (CD9, Bcl-2, CD200, CD24, prominin, Oct 3/4, ABCG2, and nestin). Almost all of these cells expressing high levels of ALDH activity also express Sca-1 and a third of them express high levels of this antigen. The cells with high levels of ALDH activity have greater in vitro proliferative potential than cells with low ALDH activity. Importantly, in an in vivo prostate reconstitution assay, the cells expressing high levels of ALDH activity were much more effective in generating prostatic tissue than a population of cells with low enzymatic activity. Thus, a high level of ALDH activity can be considered a functional marker of prostate stem/progenitor cells and allows for simple, efficient isolation of cells with primitive features. The elucidation of the role of ALDH in prostate stem/progenitor cells may lead to the development of rational therapies for treating prostate cancer and benign prostatic hyperplasia.

Disclosure of potential conflicts of interest is found at the end of this article.
Visual evoked potentials in succinate semialdehyde dehydrogenase (SSADH) deficiency
Authors: Di Rosa G. , Malaspina P. , Blasi P. , Dionisi‐Vici C. , Rizzo C. , Tortorella G. , Crutchfield S. R. , Gibson K. M.
Published: May 2009

In mammals, increased GABA in the central nervous system has been associated with abnormalities of visual evoked potentials (VEPs), predominantly manifested as increased latency of the major positive component P100. Accordingly, we hypothesized that patients with a defect in GABA metabolism, succinate semialdehyde dehydrogenase (SSADH) deficiency (in whom supraphysiological levels of GABA accumulate), would manifest VEP anomalies. We evaluated VEPs on two patients with confirmed SSADH deficiency. Whereas the P100 latencies and amplitudes for binocular VEP analyses were within normal ranges for both patients, the P100 latencies were markedly delayed for left eye (OS) (and right eye (OD), patient 1) and monocular OS (patient 2): 134–147 ms; normal <118 ms. We hypothesize that elevated GABA in ocular tissue of SSADH patients leads to a use‐dependent downregulation of the major GABAergic receptor in eye, GABAC, and that the VEP recordings’ abnormalities, as evidenced by P100 latency and/or amplitude measurements, may be reflective of abnormalities within visual systems. This is a preliminary finding that may suggest the utility of performing VEP analysis in a larger sample of SSADH‐deficient patients, and encourage a neurophysiological assessment of GABAC receptor function in Aldh5a1−/− mice to reveal new pathophysiological mechanisms of this rare disorder of GABA degradation.
Electrostatically Shielded Quantum Confined Stark Effect Inside Polar Nanostructures
Authors: Riyopoulos Spilios
Published: May 2009

The effect of electrostatic shielding of the polarization fields in nanostructures at high carrier densities is studied. A simplified analytical model, employing screened, exponentially decaying polarization potentials, localized at the edges of a QW, is introduced for the ES-shielded quantum confined Stark effect (QCSE). Wave function trapping within the Debye-length edge-potential causes blue shifting of energy levels and gradual elimination of the QCSE red-shifting with increasing carrier density. The increase in the e−h wave function overlap and the decrease of the radiative emission time are, however, delayed until the “edge-localization” energy exceeds the peak-voltage of the charged layer. Then the wave function center shifts to the middle of the QW, and behavior becomes similar to that of an unbiased square QW. Our theoretical estimates of the radiative emission time show a complete elimination of the QCSE at doping densities ≥1020 cm−3, in quantitative agreement with experimental measurements.
Effects of amino acid neurotransmitters on spontaneous muscular activity of the rumen amphistome, Gastrothylax crumenifer
Authors: Verma P.K. , Kumar D. , Tandan S.K.
Published: May 2009

Amino acid neurotransmitters play an important role in regulating neuromuscular activity of helminth parasites. The present study aimed to investigate the effects of different amino acid neurotransmitters [l-glutamate, glycine, gamma-aminobutyric acid (GABA)] on spontaneous muscular activity of isometrically mounted Gastrothylax crumenifer. l-Glutamate caused a significant increase in the amplitude and frequency of spontaneous contractions of rumen fluke at 10− 7–10− 4 m and at 10− 5–10− 4 m concentrations, respectively. Glycine application (10− 7–10− 3 m) produced a significant decrease in the amplitude and frequency of spontaneous muscular contractions in a concentration-dependent manner, as compared to control amplitude (0.53 ± 0.02 g) and frequency (51 ± 4.65/5 min). Similarly, GABA produced a significant (P < 0.05) decrease in amplitude, baseline tension and frequency of spontaneous muscular contractions of G. crumenifer. To further substantiate the GABA effect, GABAA receptor antagonists, picrotoxin and bicuculline were applied. Picrotoxin (10− 5–10− 3 m) caused a significant (P < 0.05) increase in amplitude, baseline tension and frequency of the rumen fluke as compared to control; whereas bicuculline did not elicit any observable effect in these attributes in isometrically mounted rumen flukes. These observations suggested that l-glutamate has an excitatory, whereas GABA and glycine have an inhibitory, effect on the spontaneous muscular activity of G. crumenifer.
Structure of the open conformation of a functional chimeric NADPH cytochrome P450 reductase
Authors: Aigrain Louise , Pompon Denis , Moréra Solange , Truan Gilles
Published: May 2009

Two catalytic domains, bearing FMN and FAD cofactors, joined by a connecting domain, compose the core of the NADPH cytochrome P450 reductase (CPR). The FMN domain of CPR mediates electron shuttling from the FAD domain to cytochromes P450. Together, both enzymes form the main mixed‐function oxidase system that participates in the metabolism of endo‐ and xenobiotic compounds in mammals. Available CPR structures show a closed conformation, with the two cofactors in tight proximity, which is consistent with FAD‐to‐FMN, but not FMN‐to‐P450, electron transfer. Here, we report the 2.5 Å resolution crystal structure of a functionally competent yeast–human chimeric CPR in an open conformation, compatible with FMN‐to‐P450 electron transfer. Comparison with closed structures shows a major conformational change separating the FMN and FAD cofactors from 86 Å.
The SecY complex forms a channel capable of ionic discrimination
Authors: Dalal Kush , Duong Franck
Published: May 2009

Protein translocation across the bacterial membrane occurs at the SecY complex or channel. The resting SecY channel is impermeable to small molecules owing to a plug domain that creates a seal. Here, we report that a channel loosely sealed, or with a plug locked open, does not, however, lead to general membrane permeability. Instead, strong selectivity towards small monovalent anions, especially chloride, is observed. Mutations in the pore ring‐structure increase both the translocation activity of the channel and its ionic conductance, however the selectivity is maintained. The same ionic specificity also occurs at the onset of protein translocation and across the archaeal SecY complex. Thus, the ion‐conducting characteristic of the channel seems to be conserved as a normal consequence of protein translocation. We propose that the pore ring‐structure forms a selectivity filter, allowing cells to tolerate channels with imperfect plugs.
Magnetohydrodynamic study of three-dimensional instability of the spontaneous fast magnetic reconnection
Authors: Shimizu T. , Kondoh K. , Shibata K. , Ugai M.
Published: May 2009

Three-dimensional instability of the spontaneous fast magnetic reconnection is studied with magnetohydrodynamic (MHD) simulation, where the two-dimensional model of the spontaneous fast magnetic reconnection is destabilized in three dimension. Generally, in two-dimensional magnetic reconnection models, every plasma condition is assumed to be uniform in the sheet current direction. In such two-dimensional MHD simulations, the current sheet destabilized by the initial resistive disturbance can be developed to fast magnetic reconnection by a current driven anomalous resistivity. In this paper, the initial resistive disturbance includes a small amount of fluctuations in the sheet current direction, i.e., along the magnetic neutral line. The other conditions are the same as that of previous two-dimensional MHD studies for fast magnetic reconnection. Accordingly, we may expect that approximately two-dimensional fast magnetic reconnection occurs in the MHD simulation. In fact, the fast magnetic reconnection activated on the first stage of the simulation is two dimensional. However, on the subsequent stages, it spontaneously becomes three dimensional and is strongly localized in the sheet current direction. The resulting three-dimensional fast magnetic reconnection intermittently ejects three-dimensional magnetic loops. Such intermittent ejections of the three-dimensional loops are similar to the intermittent downflows observed in the solar flares. The ejection of the three-dimensional loops seems to be random but, numerically and theoretically, it is shown that the aspect ratio of the ejected loops is limited under a criterion.
Thickness and annealing temperature dependences of magnetization reversal and domain structures in exchange biased Co/Ir–Mn bilayers
Authors: Gornakov V. S. , Tikhomirov O. A. , Lee C. G. , Jung J. G. , Egelhoff W. F.
Published: May 2009

Domain structure and magnetization reversal process of exchange-coupled ferromagnet/antiferromagnet bilayers Co(x)/Ir–Mn(10 nm) were studied as a function of both thickness of the Co layer and annealing temperature. The exchange bias field of the thinnest film and the coercive field of the thicker films show monotonic increase at annealing temperature above 250 °C. In every case the bilayers are remagnetized by domain nucleation and domain wall motion. Domain size decreases rapidly for high annealing temperatures, while x-ray diffraction study indicated that the crystallographic texture did not change significantly. The observed features are discussed taking into account the magnetic structure at the interface and its evolution during annealing.
Ultradirective antenna via transformation optics
Authors: Tichit P.-H. , Burokur S. N. , de Lustrac A.
Published: May 2009

Spatial coordinate transformation is used as a reliable tool to control electromagnetic fields. In this paper, we derive the permeability and permittivity tensors of a metamaterial able to transform an isotropically radiating source into a compact ultradirective antenna in the microwave domain. We show that the directivity of this antenna is competitive with regard to conventional directive antennas (horn and reflector antennas), besides its dimensions are smaller. Numerical simulations using finite element method are performed to illustrate these properties. A reduction in the electromagnetic material parameters is also proposed for an easy fabrication of this antenna from existing materials. Following that, the design of the proposed antenna using a layered metamaterial is presented. The different layers are all composed of homogeneous and uniaxial anisotropic metamaterials, which can be obtained from simple metal-dielectric structures. When the radiating source is embedded in the layered metamaterial, a highly directive beam is radiated from the antenna.
Temperature profiles derived from transverse optical shadowgraphy in ultraintense laser plasma interactions at 6×1020 W cm−2
Authors: Lancaster K. L. , Pasley J. , Green J. S. , Batani D. , Baton S. , Evans R. G. , Gizzi L. , Heathcote R. , Hernandez Gomez C. , Koenig M. , Koester P. , Morace A. , Musgrave I. , Norreys P. A. , Perez F. , Waugh J. N. , Woolsey N. C.
Published: May 2009

A variety of targets with different dimensions and materials was irradiated using the VULCAN PW laser [C. N. Danson et al., Nucl. Fusion 44, S239 (2004)]. Using transverse optical shadowgraphy in conjunction with a one-dimensional radiation hydrodynamics code it was possible to determine a longitudinal temperature gradient. It was demonstrated for thick targets with a low Z substrate and a thin higher Z tracer layer at the rear that the boundary between the two materials was Rayleigh–Taylor unstable. By including a simple bubble growth model into the calculations it was possible to correct for the associated behavior with regard to temperature. The resulting temperature gradient was in good agreement with the previously published data using two different methods of determining the temperature.
Coupled analysis of high and low frequency resonant ultrasound spectroscopy: Application to the detection of defects in ceramic balls
Authors: Deneuville François , Duquennoy Marc , Ouaftouh Mohammadi , Jenot Frédéric , Ourak Mohamed , Desvaux Sébastien
Published: May 2009

A coupled analysis of high and low frequency resonant ultrasound spectroscopy of spheroidal modes is presented in this paper. Experimentally, by using an ultrasonic probe for the excitation (piezoelectric transducer) and a heterodyne optic probe for the receiver (interferometer), it was possible to take spectroscopic measurements of spheroidal vibrations over a large frequency range of 100 kHz–45 MHz in a continuous regime. This wide analysis range enabled variations in velocity due to the presence of defects to be differentiated from the inherent characteristics of the balls and consequently, it offers the possibility of detecting cracks independently of production variations. This kind of defect is difficult to detect because the C-shaped surface crack is very small and narrow (500×5 μm2), and its depth does not exceed 50 μm. The proposed methodology can excite spheroidal vibrations in the ceramic balls and detect such vibrations over a large frequency range. On the one hand, low frequency resonances are used in order to estimate the elastic coefficients of the balls according to various inspection depths. This method has the advantage of providing highly accurate evaluations of the elastic coefficients over a wide frequency range. On the other hand, high frequency vibrations are considered because they are similar to the surface waves propagating in the surface zone of the ceramic balls and consequently can be used to detect C-crack defects.
High responsivity A-plane GaN-based metal-semiconductor-metal photodetectors for polarization-sensitive applications
Authors: Navarro A. , Rivera C. , Pereiro J. , Muñoz E. , Imer B. , DenBaars S. P. , Speck J. S.
Published: May 2009

The fabrication and characterization of metal-semiconductor-metal polarization-sensitive photodetectors based on A-plane GaN grown on R-plane sapphire substrates is reported. These photodetectors take advantage of the in-plane crystal anisotropy, which results in linear dichroism near the band gap energy. The high resistivity of the A-plane GaN material leads to extremely low dark currents. For an optimized finger spacing of 1 μm, dark current density and responsivity at 30 V are 0.3 nA/mm2 and 2 A/W, respectively. A maximum polarization sensitivity ratio of 1.8 was determined. In a differential configuration, the full width at half maximum of the polarization-sensitive region is 8.5 nm.
DNA relaxation dynamics as a probe for the intracellular environment
Authors: Fisher J. K. , Ballenger M. , O'Brien E. T. , Haase J. , Superfine R. , Bloom K.
Published: May 2009

Investigations into the biophysical properties of single molecules traditionally involve well defined in vitro systems where parameters such as solvent viscosity and applied forces are known a priori. These systems provide means to develop models describing the polymers response to a variety of conditions, including the entropically driven relaxation of a stretched biopolymer upon release of the tension inducing force. While these techniques have proven instrumental for recent advancements in the fields of polymer physics and biophysics, how applicable they are to life inside the cell remains poorly understood. Here we report an investigation of in vivo stretched polymer relaxation dynamics using chromatin relaxation following the breakage of a dicentric chromosome subjected to microtubule-based spindle forces. Additionally, we have developed an in vitro system used to verify the conformations observed during the in vivo relaxation, including the predicted but previously unidentified taut conformation. These observations motivate our use of existing polymer models to determine both the in vivo viscosity as seen by the relaxing chromatin and the tension force applied by the microtubule-based spindle in vivo. As a result, the technique described herein may be used as a biophysical strategy to probe the intranuclear environment.