bluuebunny/crossref_metadata_2025 huggingface dataset:
Infectivity of arbuscular mycorrhizal fungi after wetting and drying
Authors: BRAUNBERGER PETER G. , ABBOTT L. K. , ROBSON A. D.
Published: April 2006

summary

In a mediterranean environment, a hot and dry summer is followed by a cool and rainy winter, the growing season. Arbuscular mycorrhizal (AM) fungi survive in dry soil in the summer and are able to colonize newly emerged plants in winter. However, late summer and autumn rains are frequently followed by periods of drought, resulting in the wetting and drying of the soil before the onset of regular winter rains. The results of three experiments investigating the effect of wetting and drying of soil on the subsequent infectivity of different AM fungi and their individual propagules are presented.

In a first experiment, pot‐culture inoculum of Acaulospora laevis Gerd. & Trappe, Glomus invermaium Hall, or fine endophytes, each containing a mixture of propagule forms, was mixed into pots of steam‐sterilized soil with low phosphorus content. Pots were treated with a wetting and drying cycle where the soil was watered to field capacity for three consecutive days and then left to dry to a water content of less than 1.5% g g−1. Infectivity was assessed in a subsequent growth cycle planted with clover. In a second experiment, the infectivity of spores of A. laevis, Glomus monosporum Gerd. & Trappe or Scutellospora calospora (Nicol & Gerd.) Walkers & Sanders, and of dried mycorrhizal root fragments of G. invermaium or S. calospora was assessed after a wetting and drying cycle in which the soil was watered to field capacity for seven consecutive days before drying. In a third experiment, the infectivity of the extraradical hyphae of G. invermaium after wetting and drying was assessed.

AM fungi and their individual propagules responded differently to wetting and drying. The infectivity of pot‐culture inoculum of A. laevis, G. invermaium and fine endophytes was increased, decreased and unaffected, respectively, by wetting and drying. The infectivity of spores of A. laevis and G. monosporum was increased by wetting and drying but the infectivity of spores of 5. calospora was not affected. Infectivity of mycorrhizal root fragments of G. invermaium and S. calospora was decreased and increased, respectively, by wetting and drying. Finally, the infectivity of the extraradical hyphae of G. invermaium was eliminated by a wetting and drying cycle.

These results indicate that the development and function of mycorrhizas after late summer and early autumn rains may be limited by the occurrence and predominance of propagules of different AM fungi.
Evidence for an up‐regulation of the host and a down‐regulation of the fungal phosphofructokinase activity in ectomycorrhizas of Norway spruce and fly agaric
Authors: SCHAEFFER CHRISTOPH , JOHANN PATRIK , NEHLS UWE , HAMPP RÜDIGER
Published: April 2006

summary

For an understanding of metabolic interactions in ectomycorrhizal associations it is essential to distinguish enzyme activities of the symbionts. For the ATP‐dependent phosphofructokinase (PFK) from ectomycorrhizas of fly agaric (Amanita muscaria (L. ex Fr.) Hooker) on Norway spruce (Picea abies (L.) Karst.) we were able to achieve a symbiont‐specific differentiation by special assay conditions. Substrate concentrations, Mg2+: ATP ratio and pH values which were optimum for the fly agaric PFK completely suppressed the PFK activity of spruce roots. On the other hand, under the optimum assay conditions for the spruce root PFK, the fungal PFK activity was reduced by more than 90%. The most pronounced difference between the enzymes of both organisms was the response towards fructose‐2,6‐bisphosphate (F26BP); whereas F26BP had no influence on the spruce PFK activity, the fly agaric PFK activity was strongly enhanced by very low levels of F26BP.

The distinction of the partner‐specific PFK activities illustrated that mycorrhiza formation exerted partner‐specific effects. On the basis of host d. wt of the mycorrhizas, the host‐specific PFK activity was more than doubled compared with that of the non‐mycorrhizal short roots. By contrast, the fungal PFK activity, on a fungal d.wt basis, was reduced in the mycorrhizas to less than 1/4 of the activity of the free‐living mycelium.
Effects of jasmonic acid on mycorrhizal Allium sativum
Authors: REGVAR MARJANA , GOGALA NADA , ZALAR POLONA
Published: April 2006

summary

In experiments on spruce we have shown that jasmonic acid (JA), a cyclopentanone fatty acid, influences the ectomycorrhizal formation: we therefore also applied it to an endomycorrhizal symbiosis.

Garlic (Allium sativum (L.)) bulbs were potted into substrates inoculated or not with arbuscular mycorrhizal fungi (AMF), and one half of the plants was foliar‐treated with 5 μm JA. A synergistic effect of JA treatment and AMF inoculation on shoot length was found. Root growth of inoculated plants was accelerated especially when JA was applied. Either JA or AMF inoculation significantly enhanced bulb development. Mycorrhizal colonization was promoted and the development of arbuscules and vesicles was enhanced upon JA application.
CpNifS‐dependent iron‐sulfur cluster biogenesis in chloroplasts
Authors: Ye Hong , Pilon Marinus , Pilon‐Smits Elizabeth A. H.
Published: April 2006

Iron‐sulfur (Fe‐S) clusters are important prosthetic groups in all organisms. The biosynthesis of Fe‐S clusters has been studied extensively in bacteria and yeast. By contrast, much remains to be discovered about Fe‐S cluster biogenesis in higher plants. Plant plastids are known to make their own Fe‐S clusters. Plastid Fe‐S proteins are involved in essential metabolic pathways, such as photosynthesis, nitrogen and sulfur assimilation, protein import, and chlorophyll transformation. This review aims to summarize the roles of Fe‐S proteins in essential metabolic pathways and to give an overview of the latest findings on plastidic Fe‐S assembly. The plastidic Fe‐S biosynthetic machinery contains many homologues of bacterial mobilization of sulfur (SUF) proteins, but there are additional components and properties that may be plant‐specific. These additional features could make the plastidic machinery more suitable for assembling Fe‐S clusters in the presence of oxygen, and may enable it to be regulated in response to oxidative stress, iron status and light.
Chronic pain‐induced emotional dysfunction is associated with astrogliosis due to cortical δ‐opioid receptor dysfunction
Authors: Narita Minoru , Kuzumaki Naoko , Narita Michiko , Kaneko Chihiro , Hareyama Nana , Miyatake Mayumi , Shindo Keiko , Miyoshi Kan , Nakajima Mayumi , Nagumo Yasuyuki , Sato Fumiaki , Wachi Hiroshi , Seyama Yoshiyuki , Suzuki Tsutomu
Published: April 2006

It has been widely recognized that chronic pain could cause physiological changes at supraspinal levels. The δ‐opioidergic system is involved in antinociception, emotionality, immune response and neuron‐glia communication. In this study, we show that mice with chronic pain exhibit anxiety‐like behavior and an increase of astrocytes in the cingulate cortex due to the dysfunction of cortical δ‐opioid receptor systems. Using neural stem cells cultured from the mouse embryonic forebrain, astrocyte differentiation was clearly observed following long‐term exposure to the selective δ‐opioid receptor antagonist, naltrindole. We also found that micro‐injection of either activated astrocyte or astrocyte‐conditioned medium into the cingulate cortex of mice aggravated the expression of anxiety‐like behavior. Our results indicate that the chronic pain process promotes astrogliosis in the cingulate cortex through the dysfunction of cortical δ‐opioid receptors. This phenomenon may lead to emotional disorders including aggravated anxiety under chronic pain‐like state.
Molecular morphology and toxicity of cytoplasmic prion protein aggregates in neuronal and non‐neuronal cells
Authors: Grenier Catherine , Bissonnette Cyntia , Volkov Leonid , Roucou Xavier
Published: April 2006

Recent studies have revealed that accumulation of prion protein (PrP) in the cytoplasm results in the production of aggregates that are insoluble in non‐ionic detergents and partially resistant to proteinase K. Transgenic mice expressing PrP in the cytoplasm develop severe ataxia with cerebellar degeneration and gliosis, suggesting that cytoplasmic PrP may play a role in the pathogenesis of prion diseases. The mechanism of cytoplasmic PrP neurotoxicity is not known. In this report, we determined the molecular morphology of cytoplasmic PrP aggregates by immunofluorescence and electron microscopy, in neuronal and non‐neuronal cells. Transient expression of cytoplasmic PrP produced juxtanuclear aggregates reminiscent of aggresomes in human embryonic kidney 293 cells, human neuroblastoma BE(2)‐M17 cells and mouse neuroblastoma N2a cells. Time course studies revealed that discrete aggregates form first throughout the cytoplasm, and then coalesce to form an aggresome. Aggresomes containing cytoplasmic PrP were 1–5‐µm inclusion bodies and were filled with electron‐dense particles. Cytoplasmic PrP aggregates induced mitochondrial clustering, reorganization of intermediate filaments, prevented the secretion of wild‐type PrP molecules and diverted these molecules to the cytoplasm. Cytoplasmic PrP decreased the viability of neuronal and non‐neuronal cells. We conclude that any event leading to accumulation of PrP in the cytoplasm is likely to result in cell death.
Two members of the TRPP family of ion channels, Pkd1l3 and Pkd2l1, are co‐expressed in a subset of taste receptor cells
Authors: LopezJimenez Nelson D. , Cavenagh Margaret M. , Sainz Eduardo , Cruz‐Ithier Mayra A. , Battey James F. , Sullivan Susan L.
Published: April 2006

Taste receptors cells are responsible for detecting a wide variety of chemical stimuli. Several molecules including both G protein coupled receptors and ion channels have been shown to be involved in the detection and transduction of tastants. We report on the expression of two members of the transient receptor potential (TRP) family of ion channels, PKD1L3 and PKD2L1, in taste receptor cells. Both of these channels belong to the larger polycystic kidney disease (PKD or TRPP) subfamily of TRP channels, members of which have been demonstrated to be non‐selective cation channels and permeable to both Na+ and Ca2+. Pkd1l3 and Pkd2l1 are co‐expressed in a select subset of taste receptor cells and therefore may, like other PKD channels, function as a heteromer. We found the taste receptor cells expressing Pkd1l3 and Pkd2l1 to be distinct from those that express components of sweet, bitter and umami signal transduction pathways. These results provide the first evidence for a role of TRPP channels in taste receptor cell function.
Proteolytic cleavage of the neural cell adhesion molecule by ADAM17/TACE is involved in neurite outgrowth
Authors: Kalus Ina , Bormann Ulrich , Mzoughi Mounir , Schachner Melitta , Kleene Ralf
Published: April 2006

The transmembrane and multidomain neural cell adhesion molecule (NCAM) plays important functional roles in the developing and adult nervous system. NCAM is proteolytically processed and appears in soluble forms in the cerebrospinal fluid and in serum under normal and pathological conditions. In this report, we present evidence that the metalloprotease a disintegrin and a metalloprotease (ADAM)17/tumour necrosis factor α converting enzyme (TACE) cleaves the polysialylated as well as the non‐polysialylated transmembrane isoforms of NCAM, whereas the glycophosphatidylinositol‐linked isoform of NCAM is not proteolytically cleaved. A truncated, enzymatically inactive mutant of TACE did not result in release of the NCAM110 cleavage product. Proteolytic cleavage was enhanced by a calmodulin‐specific inhibitor and the actin‐destabilizing agents cytochalasin D and latrunculin B. In contrast, the microtubule‐stabilizing agent colchicine or microtubule‐destabilizing agent paclitaxel did not affect the release of the 110‐kDa fragment of NCAM. Neurite outgrowth from cerebellar microexplants was inhibited in the presence of the metalloprotease inhibitor GM 6001 on substrate‐coated NCAM, but not on poly‐l‐lysine. Upon transfection of hippocampal neurones with an enzymatically inactive mutant of TACE, NCAM‐stimulated neurite outgrowth was inhibited without affecting neurite outgrowth on poly‐l‐lysine, showing that proteolytic processing of NCAM by the metalloprotease TACE is involved in NCAM‐mediated neurite outgrowth.
Role of δ‐opioid receptor function in neurogenesis and neuroprotection
Authors: Narita Minoru , Kuzumaki Naoko , Miyatake Mayumi , Sato Fumiaki , Wachi Hiroshi , Seyama Yoshiyuki , Suzuki Tsutomu
Published: April 2006

The present study was undertaken to evaluate the implication of δ‐opioid receptor function in neurogenesis and neuroprotection. We found that the stimulation of δ‐opioid receptors by the selective δ‐opioid receptor agonist SNC80 [(+)‐4‐[(αR)‐α‐((2S,5R)‐4‐allyl‐2,5‐dimethyl‐1‐piperazinyl)‐3‐methoxybenzyl]‐N,N‐diethylbenzamide] (10 nm) promoted neural differentiation from multipotent neural stem cells obtained from embryonic C3H mouse forebrains. In contrast, either a selective µ‐opioid receptor agonist, [d‐Ala2, N‐Me‐Phe4, Gly5‐ol]‐enkephalin (DAMGO), or a specific κ‐opioid receptor agonist, (–)‐trans‐(1S,2S)‐U‐50488 hydrochloride (U50,488H), had no such effect. In addition to neural differentiation, the increase in cleaved caspase 3‐like immunoreactivity induced by H2O2 (3 µm) was suppressed by treatment with SNC80 in cortical neuron/glia co‐cultures. These effects of SNC80 were abolished by a Trk‐dependent tyrosine kinase inhibitor: (8R*,9S*,11S*)‐(–)‐9‐hydroxy‐9‐methoxycarbonyl‐8‐methyl‐2,3,9,10‐tetrahydro‐8,11‐epoxy‐1H,8H,11H‐2,7b,11a‐triazadibenzo(a,g)cycloocta(cde)trinden‐1‐one (K‐252a). The SNC80‐induced neural differentiation was also inhibited by treatment with the protein kinase C (PKC) inhibitor, phosphatidylinositol 3‐kinase (PI3K) inhibitor, mitogen‐activated protein kinase kinase (MEK) inhibitor or Ca2+/calmodulin‐dependent protein kinase II (CaMKII) inhibitor. These findings raise the possibility that δ‐opioid receptors play a crucial role in neurogenesis and neuroprotection, mainly through the activation of Trk‐dependent tyrosine kinase, which could be linked to PI3K, PKC, CaMKII and MEK.
Anandamide administration alone and after inhibition of fatty acid amide hydrolase (FAAH) increases dopamine levels in the nucleus accumbens shell in rats
Authors: Solinas Marcello , Justinova Zuzana , Goldberg Steven R. , Tanda Gianluigi
Published: April 2006

Although endogenous cannabinoid systems have been implicated in the modulation of the rewarding effects of abused drugs and food, little is known about the direct effects of endogenous ligands for cannabinoid receptors on brain reward processes. Here we show for the first time that the intravenous administration of anandamide, an endogenous ligand for cannabinoid receptors, and its longer‐lasting synthetic analog methanandamide, increase the extracellular dopamine levels in the nucleus accumbens shell of awake, freely moving rats, an effect characteristic of most drugs abused by humans. Anandamide produced two distinctly different effects on dopamine levels: (1) a rapid, transient increase that was blocked by the cannabinoid CB1receptor antagonist rimonabant, but not by the vanilloid VR1receptor antagonist capsazepine, and was magnified and prolonged by the fatty acid amide hydrolase (FAAH) enzyme inhibitor, URB597; (2) a smaller delayed and long‐lasting increase, not sensitive to CB1, VR1or FAAH blockade. Both effects were blocked by infusing either tetrodotoxin (TTX, 1 µm) or calcium‐free Ringer's solution through the microdialysis probe, demonstrating that they were dependent on the physiologic activation of dopaminergic neurotransmission. Thus, these results indicate that anandamide, through the activation of the mesolimbic dopaminergic system, participates in the signaling of brain reward processes.
WAY‐100635 antagonist‐induced plasticity of 5‐HT1A receptors: regulatory differences between a stable cell line and an in vivo native system
Authors: Khawaja Xavier Z. , Smith Deborah L. , Nawoschik Stanley P. , Zhang Jean , Dunlop John , Dilks Daniel W. , Olsen Michael , Schechter Lee E.
Published: April 2006

We present evidence that the 5‐hydroxytryptamine1A (5‐HT1A) receptor antagonist, N‐{2‐[4‐(2‐methoxyphenyl)‐1‐piperazinyl]‐ethyl}‐N‐(2‐pyridinyl)cyclohexanecarboxamide (WAY‐100635), can induce receptor internalization in a human (h)5‐HT1A receptor Chinese hamster ovary (CHO‐K1) cell system. Exposure of h5‐HT1A CHO cells to WAY‐100635 decreased the cell‐surface h5‐HT1A receptor density in a way that was both time (24–72 h) and concentration (1–100 nm) dependent.[3H]WAY‐100635 and [3H]8‐hydroxy‐dipropylaminotetralin ([3H]8‐OH‐DPAT) saturation analyses demonstrated a significant reduction (50–60%) in total h5‐HT1A receptor number in the WAY‐100635‐treated (100 nm; 72 h) compared with control cells. In WAY‐100635‐treated cells, the 8‐OH‐DPAT‐mediated inhibition of forskolin (FSK)‐stimulated cAMP accumulation was right‐shifted and the maximal inhibitory response of 8‐OH‐DPAT was impaired compared with control cells. Similar results were obtained for 8‐OH‐DPAT‐mediated Ca2+ mobilization after WAY‐100635 treatment. h5‐HT1A receptors labeled with [3H]WAY‐100635, as well as [3H]4‐(2′‐Methoxy)‐phenyl‐1‐[2′‐(N‐2′′‐pyridinyl)‐p‐fluorobenzamido]ethyl‐piperazine (MPPF), exhibited a time‐dependent rate of cellular internalization that was blocked by endocytotic suppressors and was pertussis‐toxin insensitive. In contrast, quantitative autoradiographic studies demonstrated that chronic treatment of rats with WAY‐100635 for two weeks produced a region‐specific increase in the 5‐HT1A receptor density. In conclusion, prolonged exposure of an h5‐HT1A cell‐based system to the 5‐HT1A antagonist, WAY‐100635, induced a paradoxical internalization of cell surface receptor resulting in depressed functional activity. This suggests that an antagonist can influence 5‐HT1A receptor recycling in vitro differently to in vivo regulatory conditions.
Learning to use simple massage with disabled children: parents’ experiences of a training and support programme
Authors: Savin‐Baden Maggi , Powell Lesley , Barlow Julie
Published: April 2006

This article presents a pedagogical evaluation of parents’ understanding of their own learning in relation to the Training and Support Programme they received to enable them to undertake simple massage with their disabled children. Data were gathered from exit interviews with 17 parents who had been involved over the course of 2 months. Analysis was undertaken using interpretative interactionism in order to understand the relationship between parents’ learning approaches and the training approach implemented. The findings indicated that the Training Programme largely adopted a behavioural approach that reflected the teaching practices of the trainers. However, cognitive developmental learning was also part of the overarching approach and, in the long term, this was the approach which fitted with most parents’ needs. What was particularly apparent was the importance of the relationship between the learning approaches adopted and parents’ desire to learn in a particular way. Furthermore, parents argued that the Training and Support Programme had high positive impact on their children and their family lives in general. This report is one of the first examples of an evaluation that sought to analyse and to understand the pedagogical tensions of parents’ experiences of learning on a Training and Support Programme in the UK.
The Politics of Economic Nationalism in Postrevolutionary Mexico
Authors: Gauss Susan M.
Published: April 2006

Economic nationalism in Mexico has typically been linked to mid‐twentieth‐century experiments with state‐led industrial protectionism. This article argues that the origins of this association lay in postrevolutionary conflicts between economic liberals and protectionists over state consolidation and industrial centralization. Within these struggles, promoters of state economic intervention as well as defenders of free trade and private enterprise justifiably proclaimed the nationalist merits of their divergent industrial projects. This article, by focusing on the political facets of industrialist conflicts amid rising post‐World War II concerns over United States influence, sheds light both on how the post‐World War II period became a turning point in the maturation of industrial protectionism, as well as on the contingent nature of its mid‐twentieth‐century association with economic nationalism.
On the Significance of War, or Why Conquest is Not Necessarily Conquest: The Case of the Nineteenth‐Century United States–Mexican Border
Authors: Cayton Andrew
Published: April 2006

One strand of recent work on the nineteenth‐century borderlands between the United States and Mexico attempts to overturn Anglo‐American conventional wisdom by turning heroes into villains. Another, more significant strand reflects a general tendency among academic historians to focus on the importance of long‐term demographic, social, and economic developments at the expense of military and political events. Episodes in on‐going struggles, wars are neither as decisive nor as significant as previous generations of historians had assumed. In stressing the power and endurance of local communities, borderlands’ historians fundamentally challenge the power and permanency of nation‐states.
Endoscopic management of intrabiliary‐ruptured hepatic hydatid cyst
Authors: Singh Virendra , Reddy Deevaguntla Chandrasekhar , Verma Ganga Ram , Singh Gurpreet
Published: April 2006

Abstract: Background/aim: Intrabiliary rupture of hepatic hydatid cyst causes serious morbidity and mortality. These patients are usually managed surgically. We evaluated the feasibility and outcome of an alternative method of treatment of these patients.

Methods: Seven patients with ruptured hepatic hydatid into the biliary tract underwent endoscopic treatment consisting of endoscopic sphincterotomy, cyst material extraction and hypertonic saline lavage via nasocystic catheter.

Results: Median age of patients was 40 years (range 17–50 years) with a male:female ratio of 2:5. Abdominal pain, jaundice and fever were seen in all patients. Six out of seven patients were positive for hydatid serology. All patients were successfully treated by endoscopic sphincterotomy, clearance of cyst material and hypertonic saline lavage. On a follow‐up of 6 months to 4 years (median, 3.5 years), ultrasonography, computed tomography of the abdomen and magnetic resonance imaging of the abdomen showed a complete cure. There were no complications related to procedure.

Conclusions: This study demonstrates endoscopic treatment as one of the therapeutic options of ruptured hepatic hydatid cyst into the biliary tract.
Successful treatment of autoimmune hepatitis and idiopathic thrombocytopenic purpura with the monoclonal antibody, rituximab: case report and review of literature
Authors: Santos Edgardo S. , Arosemena Leopoldo R. , Raez Luis E. , O'Brien Christopher , Regev Arie
Published: April 2006

Abstract: Rituximab, a chimeric monoclonal anti‐CD20 antibody, has shown activity in several autoimmune disorders. We describe a case of a 52 years old female who was diagnosed with idiopathic thrombocytopenic purpura and concomitant autoimmune hepatitis (AIH), both non‐responsive to steroids. She was subsequently treated with rituximab, which resulted in a rapid increase in her platelet count and an unexpected normalization of her hepatic biochemical tests. Both her platelet count and her hepatic biochemical tests remained normal for over 5 months. In this case, rituximab showed an impressive clinical response for the treatment of AIH, and it may be considered as an alternative treatment in patients who do not respond to corticosteroid therapy. Prospective randomized studies in AIH are needed to validate this observation.
Clinical evaluation of magnetic resonance imaging flowmetry of portal and hepatic veins in patients following hepatectomy
Authors: Nanashima A. , Shibasaki S. , Sakamoto I. , Sueyoshi E. , Sumida Y. , Abo T. , Nagasaki T. , Sawai T. , Yasutake T. , Nagayasu T.
Published: April 2006

Abstract: Background: Hepatic blood flow was associated with degree of hepatic damage. Measurements of blood flow using ultrasonography (US) may vary due to any observer's and patient's conditions. The utility of magnetic resonance imaging (MRI) flowmetry in portal and hepatic veins was assessed.

Patients and methods: Using the phase‐contrast method, the mean flow velocity of portal (PVF) and hepatic vein (HVF) were determined by MRI and US in 75 consecutive patients with liver diseases, including 58 patients undergoing hepatectomy. The correlations between these parameters and clinicopathological findings were examined.

Results: PVF and HVF measured by MRI flowmetry were 12.8±4.5 and 14.7±5.3 cm/s, respectively. There was no significant correlation of both flows between MRI and US. PVF correlated significantly with portal pressure (r=−0.722; P<0.05). There was a negative correlation between HVF and histological activity index score (r=−0.366; P<0.05). PVF and HVF were lower in patients with cirrhosis and higher staging score (2–4) and PVF was lower in patients with higher grading score (2–3; P<0.05). PVF and HVF were not significantly associated with postoperative complications.

Conclusions: Our results suggest that MRI flowmetry is a potentially useful tool for measurement of hepatic blood flow and recommend its use for estimation of liver cirrhosis‐associated impairment.
Marginal Adaptation of Cerec 3 CAD/CAM Composite Crowns Using Two Different Finish Line Preparation Designs
Authors: Akbar Jaber Hussain , Petrie Cynthia S. , Walker Mary P. , Williams Karen , Eick J. David
Published: April 2006

Purpose: The purpose of this study was to compare marginal discrepancies of Cerec 3 CAD/CAM composite crowns, fabricated on human prepared teeth with two different finish line designs, chamfer and shoulder.

Materials and Methods: Sixteen human molar teeth were used to prepare full crowns. Eight teeth were prepared with a 1‐mm‐wide chamfer finish line and the other eight with a 1.2‐ to 1.5‐mm circumferential shoulder. Cerec 3 crowns were fabricated from optical impressions using Paradigm MZ100 composite polymer. Marginal adaptation was evaluated in two ways: (1) using modified United States Public Health Service (USPHS) criteria to evaluate eight preselected sites on each crown margin, and (2) using scanning electron microscopy (SEM) to measure marginal gaps on all four axial walls with 15 measurements on each wall (60 measurements per crown). An evaluation of the number of acceptable crowns, determined by having all measured sites per tooth with margin gap size less than 100 μm, as a function of finish line design was also conducted.

Results: In both chamfer and shoulder groups, there were only two crowns (out of eight) with clinically acceptable ratings for all eight measurement sites according to USPHS criteria. Fisher's chi‐square analysis showed that there was no statistically significant difference in marginal adaptability as a function of finish line design ( p > 0.05). With SEM imaging, overall mean marginal gaps for the chamfer group were 65.9 ± 38.7 μm (range 35.0 to 130.0 μm), and for the shoulder group were 46.0 ± 9.2 μm (range 26.3 to 55.6 μm); this difference was not found to be statistically significant ( p > 0.05). While crown assessment based on mean marginal discrepancy measurements indicated that both the chamfer and shoulder groups were considered clinically acceptable (<100 μm); crown acceptability based on all measurement sites being less than 100 μm indicated that in the chamfer and shoulder groups there were four and three acceptable crowns out of eight, respectively. The Fisher's chi‐square test indicated no statistically significant difference between the groups ( p > 0.05). An agreement rate of 81.2% was calculated between the two evaluation methods, modified USPHS criteria and SEM measurements.

Conclusions: Based on mean marginal discrepancy measurements, the typical marginal assessment technique, Cerec 3 Paradigm MZ100 crown restorations appear to have acceptable marginal adaptability (mean discrepancies <100 μm). Thus, the evidence from this investigation would suggest that the finish line preparation design had no effect on marginal adaptation for Cerec 3 composite crowns.
Screw‐Retained Prosthesis for Straumann Implant Sites with Limited Interocclusal Clearance
Authors: Armellini Debora , Bilko S. , Carmichael Robert P. , Von Fraunhofer J. Anthony
Published: April 2006

This article reports a technique that addresses the problem of the restricted interocclusal distance when screw‐retained prostheses are selected.
A Model for the Nanodomains in Polymer‐Derived SiCO
Authors: Saha Atanu , Raj Rishi , Williamson Don L.
Published: April 2006

The polymer‐based synthesis of ceramics such as SiCO (and SiCN) leads to the incorporation of significant amounts of carbon into their molecular structure. A key feature of the nanostructure of these polymer‐derived ceramics is the revelation of persistent, 1–5 nm size domains by small‐angle X‐ray scattering. Here we present a model for these nanodomains, which is consistent with the nuclear magnetic resonance (NMR) data and with the phenomenological properties of SiCO (high resistance to creep and viscoelastic behavior). The model consists of clusters of silica tetrahedra encased within an interdomain wall constituted from mixed bonds of SiCO, and from a network of sp2 carbon. The model predicts the domain size as a function of the carbon content. These predictions are in reasonable agreement with the measurements of the nanodomains in SiCO synthesized with varying carbon contents (the domain size decreases with higher carbon). Simple maps are developed for easy reading of the domain size and the width of the interdomain boundary in the composition diagrams.
Electrospinning: A Simple and Versatile Technique for Producing Ceramic Nanofibers and Nanotubes
Authors: Li Dan , McCann Jesse T. , Xia Younan , Marquez Manuel
Published: April 2006

Electrospinning is a remarkably simple method for generating nanofibers of polymers. When combined with conventional sol–gel processing, it provides a versatile technique for producing ceramic nanofibers with either a solid, porous, or hollow structure. This article presents a brief overview of recent progress in preparation of ceramic nanofibers by electrospinning, with a focus on an introduction to experimental procedures and analysis of several technical issues that are vital for a successful electrospinning experiment. We also highlight the unique capabilities of this technique in processing ceramic materials into nanostructures, and illustrate some potential applications of these nanostructures.
Red Color GeSe2‐Based Chalcohalide Glasses for Infrared Optics
Authors: Yang Zhiyong , Luo Lan , Chen Wei
Published: April 2006

GeSe2–Ga2Se3–CsI chalcohalide glasses are synthesized, and their optical properties and thermo‐mechanical properties are studied. A typical characteristic of the glasses is their excellent transparency in the red‐light region in addition to the 8–14 μm atmospheric window, which is of vital importance to the quality control of infrared systems. The short‐wavelength absorption edge λs of the glass system has a distinct blue shift with increasing CsI content, and the physicochemical interpretations are suggested and formulated. These glasses present a glass transition temperature (Tg) around 300°C and good thermal stability. Consequently, they can be promising candidate materials for infrared optics, although their hardness is relatively weak.
Fabrication and Photoluminescence Characteristics of Eu3+‐Doped Lu2O3 Transparent Ceramics
Authors: Chen Qiwei , Shi Ying , An Liqiong , Chen Jiyang , Shi Jianlin
Published: April 2006

A novel co‐precipitation process was adopted for the preparation of highly sinterable europium‐doped lutetia powders using ammonium hydroxide (NH3·H2O) and ammonium hydrogen carbonate (NH4HCO3) as the mixed precipitant. The resultant powders calcined at 1000°C for 2 h showed good dispersity and excellent sinterability. Highly transparent polycrystalline lutetia ceramics with a relative density of ∼99.9% were fabricated by pressureless sintering in flowing H2 atmosphere at 1850°C for 6 h without any additives. The average grain sizes of the transparent material were estimated to be 50–60 μm. Optical in‐line transmittance in the visible wavelength region for Lu2O3 ceramics (1 mm in thickness) reached 80%. The luminescence and decay behavior of the obtained transparent plate and the corresponding nanophosphors were also investigated.
Strengthening of Porous Mullite and Zirconia CMC Matrices by Evaporation/Condensation
Authors: Haslam Jeffery J. , Lange Frederick F.
Published: April 2006

A processing method using evaporation/condensation sintering in an HCl atmosphere was developed for strengthening porous materials without shrinkage. Strengthening without shrinkage is useful in preventing voids and cracks that might be formed during constrained densification, e.g., a porous matrix in a continuous fiber reinforced ceramic composite. Mixtures of mullite and zirconia (monoclinic, tetragonal (3 mol% Y2O3), and cubic (8 mol% Y2O3)) were studied and exposed to HCl vapor at temperatures up to 1300°C. It was observed that the evaporation–condensation mass transport process produced a porous material with minimal shrinkage. As the crystal structure of the starting tetragonal and cubic zirconia powders did not change after extensive coarsening, it appeared that zirconium and yttrium were transported in the same proportion via evaporation/condensation. The process produced significant coarsening of the zirconia grains, which made the material resistant to densification when heated to 1200°C in air. Because the sintering produced coarsening without shrinkage, the pores also coarsened and a porous microstructure was retained. Mixtures of mullite and zirconia were used because mullite does not densify under the processing conditions used here, namely, heat treatments up to 1300°C. The mullite particles acted as a non‐densifying second phase to further inhibit shrinkage when the mullite/zirconia composite was heated up to 1200°C in air. The coarsened cubic zirconia plus mullite mixture had the least densification after heat treatments in air of 100 h at 1200°C.
Tunable Linear Thermal Expansion Coefficient of Amorphous Zirconium Tungstate
Authors: Catafesta Jadna , Zorzi Janete E. , Perottoni Cláudio A. , Gallas Márcia R. , Da Jornada João Alziro H.
Published: April 2006

Zirconium tungstate (α‐ZrW2O8) exhibits isotropic negative thermal expansion over a wide range of temperatures. Under high pressure it transforms to a metastable amorphous phase with positive thermal expansion coefficient. α‐ZrW2O8 can be fully recovered by annealing the amorphous phase at temperatures slightly above 600°C, at room pressure. In this work, we describe the dependency of the linear thermal expansion coefficient of amorphous ZrW2O8 with the annealing temperature, showing that it can be continuously tuned, in two stages, from about 7.5° to −9°C−1. These two stages are related to the relaxation of the amorphous phase and the onset of recrystallization, respectively.
Electron Emission from Barium Strontium Titanate Ceramics
Authors: Chen Shutao , Dong Xianlin , Zheng Shuxin , Zhu Ziqiu , Tang Chuanxiang
Published: April 2006

This paper focuses on understanding the influence of materials' properties on the ferroelectric electron emission. Ferroelectric (x=1.0 and 0.8) and paraelectric (x=0.67 and 0.5) compositions of barium strontium titanate (BaxSr(1−x)TiO3) system were chosen for study based on their different ferroelectric and dielectric properties. Similar emission current waveforms were obtained from four compositions with negative triggering voltage applied to the rear electrode of the samples. It was difficult to explain the experimental results using the spontaneous polarization‐switching model. The mechanism of electron emission from BaxSr(1−x)TiO3 ceramics was ascertained to surface plasma emission.
Effect of Addition of Silicon on the Microstructures and Bending Strength of Continuous Porous SiC–Si3N4 Composites
Authors: Paul Rajat Kanti , Gain Asit Kumar , Lee Byong‐Taek , Jang Hee‐Dong
Published: April 2006

The microstructures and mechanical properties of continuous porous SiC–Si3N4 composites fabricated by multi‐pass extrusion were investigated, depending on the amount of Si powder added. Si powder with different weight percentages (0%, 5%, 10%, 15%, 20%) was added to SiC powder to make raw mixture powders, with 6 wt% Y2O3–2 wt% Al2O3 as sintering additives, carbon (10–15 μm) as a pore‐forming agent, ethylene vinyl acetate as a binder, and stearic acid (CH3(CH2)16COOH) as a lubricant. In the continuous porous SiC–Si3N4 composites, Si3N4 whiskers like the hairs of nostrils were frequently observed on the wall of the pores. In this study, the morphology of Si3N4 whiskers was investigated with the nitridation condition and silicon addition content. In composites containing an addition of 10 wt% Si, a large number of Si3N4 whiskers were found at the continuous pore regions. In the sample to which 15 wt% Si powder was added, a maximum value of about 101 MPa bending strength and 57.5% relative density were obtained.
Investigation on Strain Recovery During Microfabrication by Colloidal Isopressing
Authors: Zhang Zhuo , Lange Frederick F.
Published: April 2006

During microfabrication of ceramics by the Colloidal Isopressing method, cracks were a major problem when features with high aspect ratios were molded into the surface. As differential strain recovery (different elastic expansion of the polymer mold material relative to the consolidated powder compact) is one cause of stress that introduces cracking during pressure release, the strain recovery of the consolidated alumina body was investigated. Spheres of different materials with different elastic moduli were embedded within a pre‐consolidated slurry and isopressed at 250 MPa. The strain recovery of the powder compact was also measured via a uni‐axial compression test. Results showed that cracks did not form when the elastic moduli of the inclusions were greater than 3 GPa. Inclusions were made by consolidating wax (low‐modulus) and aluminum (high modulus) powders so that the elastic modulus of the composite was large enough to avoid crack during pressure release. The wax was removed via a low‐temperature heat treatment. This heat treatment also strengthened the powder compact so that the residual aluminum powder could be dissolved in a weak acid. Internal cavities could be formed in dense ceramics by this method.
Anisotropic Sintering Shrinkage in Alumina Ceramics Containing Oriented Platelets
Authors: Ozer I. O. , Suvaci E. , Karademir B. , Missiaen J. M. , Carry C. P. , Bouvard D.
Published: April 2006

The effect of oriented α‐Al2O3 platelets on densification and shrinkage behavior of tape‐cast α‐Al2O3 during solid‐state sintering was studied using dilatometric sintering shrinkage experiments and microstructural characterization. Platelet‐free alumina samples exhibit isotropic shrinkage with an ∼17% linear final shrinkage. The addition of platelets retards densification, and results in anisotropic shrinkage. Initially during sintering, shrinkage is isotropic for platelet‐containing systems; however, it becomes highly anisotropic by inhibition of shrinkage in the platelet orientation direction. In the 10 vol% platelet‐containing system, shrinkage was ∼12% in the casting and the transverse directions and ∼20% in the direction perpendicular to the casting plane.
An Arrhenius‐Type Viscosity Function to Model Sintering Using the Skorohod–Olevsky Viscous Sintering Model Within a Finite‐Element Code
Authors: Reiterer M. W. , Ewsuk K. G. , Argüello J. G.
Published: April 2006

The ease and ability to predict sintering shrinkage and densification with the Skorohod–Olevsky viscous sintering (SOVS) model within a finite‐element (FE) code have been improved with the use of an Arrhenius‐type viscosity function. The need for a better viscosity function was identified by evaluating SOVS model predictions made using a previously published polynomial viscosity function. Predictions made using the original, polynomial viscosity function do not accurately reflect experimentally observed sintering behavior. To more easily and better predict sintering behavior using FE simulations, a thermally activated viscosity function based on creep theory was used with the SOVS model. In comparison with the polynomial viscosity function, SOVS model predictions made using the Arrhenius‐type viscosity function are more representative of experimentally observed viscosity and sintering behavior. Additionally, the effects of changes in heating rate on densification can easily be predicted with the Arrhenius‐type viscosity function. Another attribute of the Arrhenius‐type viscosity function is that it provides the potential to link different sintering models. For example, the apparent activation energy, Q, for densification used in the construction of the master sintering curve for a low‐temperature cofire ceramic dielectric has been used as the apparent activation energy for material flow in the Arrhenius‐type viscosity function to predict heating rate‐dependent sintering behavior using the SOVS model.
In Situ Neutron and X‐Ray Powder Diffraction Study of Cation Ordering and Domain Growth in the Dielectric Ceramic Ba3ZnTa2O9–Sr2GaTaO6
Authors: Ibberson R. M. , Moussa S. M. , Rosseinsky M. J. , Fitch A. N. , Iddles D. , Price T.
Published: April 2006

In situ methods are ideally suited to study the development of property‐critical structural features during material processing. As an example of their potential in the area of complex oxide electroceramics, here, we apply X‐ray synchrotron and neutron powder diffraction to investigate the ordering processes responsible for optimizing the microwave dielectric properties of the commercial electroceramic barium zinc tantalate (BZT) doped with strontium gallate. The collection of synchrotron diffraction data with high resolution and high intensity during processing has allowed the development of cation site order and growth of ordered domains to be followed during the multi‐stage thermal treatment processing used by industry. Complementary neutron diffraction data reveal changes in the cation–oxygen bonding associated with development of the cation‐ordered trigonal perovskite structure. The effects of material loss with processing at temperatures of up to 1525°C are discussed following experiments using open and closed systems. The complex nature of the ordering is confirmed by the coexistence of two BZT phases and the formation of a further zinc‐deficient phase. The implications of these observations and relation to the industrial processing procedures are discussed.
Mucinous syringometaplasia with prominent epithelial hyperplasia and deep dermal involvement
Authors: Madison Jennifer F. , Cooper Philip H. , Burgdorf Walter H. C.
Published: April 2006

This report describes two patients with mucinous syringometaplasia whose findings expand the microscopic and clinical spectrum of the entity. The first patient had an eroded nodule that exhibited multiple epidermal invaginations that penetrated deeply into the dermis. In addition to mucinous metaplasia, there was also exuberant papillary epithelial hyperplasia. Expanded eccrine ducts with similar changes appeared as lobules isolated in the dermis but were shown to connect with the invaginations. In the second patient, a clinical “cyst” drained serous fluid. Multiple papillary‐cystic epithelial lobules similar to those seen in the first case were located in the dermis. A few approached the epidermis, but epidermal connections were not identified. The epithelium in these lesions was identical to that previously described in mucinous syringometaplasia. The tumors differed from prior cases by virtue of the number of eccrine apparatus involved, the extent and depth of involvement, and the presence of prominent papillary epithelial hyperplasia.
Ultrastructural study of exclamation‐mark hair shafts in alopecia areata
Authors: Tobin Desmond J. , Fenton David A. , Kendall Marion D.
Published: April 2006

The prime diagnostic feature of acute alopecia areata is the presence of exclamation mark hairs. These characteristic hairs fracture at their distal end and taper proximally towards the scalp, giving them the appearance of an exclamation mark. Hair morphology was studied in 8 patients with untreated acute alopecia areata and 3 normal adults without hair loss. Light microscopy, transmission and scanning electron microscopy revealed distinct structural differences in the distal end of hairs compared with the remainder of their length and with normal hair shafts. Transverse sections of hairs just below the frayed brush‐like tip often displayed asymmetrical cortex disintegration. One side was compact and homogeneous while the other was deeply fissured and/or broken up into discrete heterogeneous‐staining fragments of cortical, stratum corneum and cuticular components in addition to apparently degenerate cortex. Many exclamation mark hair tips lacked cuticle and had irregular profiles. Melanin was found in cortical and medullary fragments at the tip, although it was absent in the more degenerate forms of cortex. More proximal sections of these pathognomic telogen hairs revealed nearly normal hair shaft ultrastructure.
Neuropeptides in cutaneous neurofibromas of Von Recklinghausen's disease
Authors: Vaalasti A. , Suomalainen H. , Kuokkanen K. , Rechardt L.
Published: April 2006

The occurrence of neuropeptides was studied in neurofibromas of von Recklinghausen's disease by indirect immunofluorescence. All non‐plexiform cutaneous neurofibromas contained abundant vasoactive intestinal polypeptide, peptide histidine–isoleucine and calcitonin gene‐related peptide immunoreactive nerves. The nerves were small and unmyelinated. Neuropeptides might be responsible for itch that occurs especially in small cutaneous neurofibromas. Neuropeptides are also suggested to act as modulators and/or trophic factors for neurofibroma growth.
Primary cutaneous adenoid cystic carcinoma: ultrastructural study and immunolocalization of Types I, III, IV, V collagens and laminin
Authors: Fukai K. , Ishii M. , Kobayashi H. , Chanoki M. , Furukawa M. , Nakagawa K. , Hamada T. , Abe Y. , Ooshima A.
Published: April 2006

A primary adenoid cystic carcinoma of the skin is reported. Light microscopy revealed pseudocysts. PAS‐positive basement membrane and true glandular lumen, which in aggregates are specific for adenoid cystic carcinoma. Perineural invasion was also observed. Ultrastructural examinations revealed three types of cystic spaces; pseudocysts, true glandular lumens and intercellular spaces. Enzyme histochemical examinations showed positive reactions for eccrine enzymes, including phosphorylase and succinic dehydrogenase and negative for apocrine enzymes. Immunolocalization of collagens and laminin revealed that basement membranes of the pseudocysts involve Type V collagen as well as Type IV collagen and laminin.