bluuebunny/crossref_metadata_2025 huggingface dataset:
Dilated Intercellular Spaces
Authors: Ravelli Alberto M. , Villanacci Vincenzo , Ruzzenenti Nella , Grigolato Piergiovanni , Tobanelli Pamela , Klersy Catherine , Rindi Guido
Published: May 2006

Objectives:

Dilated intercellular spaces (DIS) in the esophageal epithelium have been identified by electron microscopy as marker of acid reflux damage in experimental animals and adults with gastroesophageal reflux disease (GERD). We aimed to identify and quantify DIS by light microscopy in pediatric GERD and esophagitis.

Methods:

We prospectively took esophageal biopsies in 70 consecutive pediatric patients, 48 of whom had GERD symptoms. On hematoxylin and eosin‐stained sections esophagitis was scored histologically, and DIS were graded as 0 (absent), + (small and focal), ++ (moderate) or +++ (large and diffuse). A computerized image analysis identified total, cellular and nuclear areas and DIS were quantified as percentage of total minus cellular area.

Results:

Forty of 48 GERD patients had histological esophagitis (33 G1, 4 G2, 3 G3, 1 of which with Barrett esophagus), and all 40 had DIS (33 +, 4 ++, 3 +++) with 100% interobserver agreement; 15 of 29 (55%) had abnormal pH study (reflux index, 5.7%‐36%). In 30 patients the esophagus was histologically normal. DIS values were 2.21% ± 2.60% (range, 0.11%‐12%) in patients with esophagitis and 0.44% ± 0.13% (0.2%‐0.7%) in patients with normal histology (P < 0.00001), with 0.71% bearing 70% sensitivity and 100% specificity for GERD versus controls. Five other children with esophagitis unrelated to GERD (eosinophilic, Candida, food allergy) also had DIS + to +++, and median DIS area was 5% (1.3%‐12%).

Conclusions:

DIS can be detected and evaluated by light microscopy, and the image analysis used provides an objective quantification of DIS and supports the light microscopy evaluation. DIS are a morphological feature of GERD and esophagitis in infancy and childhood.
Superior Mesenteric Artery Syndrome in Children
Authors: Biank Vincent , Werlin Steven
Published: May 2006

Objectives:

Superior mesenteric artery syndrome (SMAS), Wilkie syndrome or cast syndrome is a rare condition that usually presents with symptoms of mid to upper gastrointestinal obstruction due to the compression of the duodenum between the abdominal aorta, posteriorly, and the superior mesenteric artery, anteriorly. The aim of this study was to analyze the clinical characteristics, means of diagnosis and management of SMAS in a pediatric population.

Methods:

Retrospective chart review of all patients at the Children's Hospital of Wisconsin with SMAS from 1985 to 2005.

Results:

Twenty‐two cases of SMAS where diagnosed at Children's Hospital of Wisconsin between 1985 and 2005 [14, (64%) female]. Symptoms developed 1 to 393 days (median 5 days) before diagnosis. Presenting symptoms included abdominal pain (59%), vomiting (50%), nausea (40%), early satiety (32%) and anorexia (18%). Diagnosis was made by upper‐gastrointestinal radiography in 18 (82%), by computed tomography in 2 (9%) and at laparotomy in 2 (9%). One patient was treated surgically after medical management failed. Mean length of treatment was 65 days (range 13‐169), with a mean length of hospitalization of 21 days (range 0‐68 days).

Conclusion:

SMAS usually presents more acutely than chronically with symptoms of small bowel obstruction. Weight loss is not necessary for SMAS development. Prior neurological injury may be a risk factor for development of SMAS. Upper gastrointestinal radiography remains the primary means of diagnosis. SMAS is typically successfully managed medically. Surgical intervention should be reserved for patients' refractory to medical therapy. The expected outcome of SMAS is excellent.
Endoscopic Management of Sphincter of Oddi Dysfunction in Children
Authors: Varadarajulu Shyam , Wilcox C. Mel
Published: May 2006

Background:

Data on sphincter of Oddi dysfunction (SOD) in children are scant. Most children diagnosed with SOD are treated by biliary sphincterotomy with suboptimal results. The efficacy and safety of pancreatic and dual sphincterotomy in children with SOD has not been previously reported.

Objective:

To evaluate the efficacy and safety of pancreatic and dual sphincterotomy in children with SOD.

Materials and Methods:

Prospective evaluation of all children who underwent endoscopic retrograde cholangiopancreatogram (ERCP) with sphincter of Oddi manometry for evaluation of suspected SOD over a 3‐year period. Children diagnosed with SOD underwent pancreatic or dual sphincterotomy with prophylactic pancreatic stenting.

Results:

SOD was diagnosed by sphincter of Oddi manometry in 6 of 11 children who underwent ERCP for suspected SOD. Of the 6 children (mean age, 11 years; range, 5‐16; 4 girls) with SOD, 3 presented with recurrent pancreatitis and 3 with postcholecystectomy pain. Pancreatic sphincter hypertension was noted in all 6 patients; concomitant biliary sphincter hypertension was noted in 3 patients with postcholecystectomy pain. Patients with recurrent pancreatitis underwent pancreatic sphincterotomy and those with postcholecystectomy pain underwent dual sphincterotomy. Prophylactic pancreatic stents were placed in all patients. One girl experienced mild post‐ERCP pancreatitis. At a mean follow‐up of 583 days (range, 325‐1445), 4 patients were asymptomatic, 1 experienced partial symptom relief and 1 had recurrent symptoms.

Conclusions:

As in adults, pancreatic and dual sphincterotomy, in expert hands, is effective and safe in a subgroup of children with SOD. Prospective, randomized trials with larger number of patients are required to validate the efficacy of endotherapy in children with SOD.
Anti‐rotavirus Antibodies in Human Milk
Authors: Asensi María Teresa , Martínez‐Costa Cecilia , Buesa Javier
Published: May 2006

Objective:

To analyze anti‐rotavirus antibodies in human milk in order to determine their isotypes and neutralizing activity on rotavirus strains representing different viral serotypes.

Methods:

One hundred seventy‐three milk samples (65 colostrum, 55 transitional milk and 53 mature milk) obtained from 65 mothers were analyzed along with 49 serum samples collected just before delivery. Total immunoglobulin A (IgA) and rotavirus‐specific IgA and immunoglobulins G (IgG) antibodies were determined in milk and serum by enzyme‐linked immunosorbent assay. Neutralizing activity was evaluated by an immunoperoxidase focus reduction assay. Milk IgA was purified by binding to the lectin jacalin, elution and ultrafiltration.

Results:

Total IgA antibodies were detected in all serum and milk samples analyzed. IgA levels decreased sharply during the replacement of colostrum by transitional milk, and more gradually from transitional to mature milk. These differences in IgA concentration during the 3 periods were statistically significant. Anti‐rotavirus antibodies detected in human milk were exclusively of the IgA type, whereas both IgA and IgG anti‐rotavirus antibodies were present in serum samples. Both milk and serum samples showed in vitro neutralization of the infectivity of rotavirus strains SA11, Wa and VA70, this activity being stronger toward the human rotavirus strain Wa. No correlation was however found between the inhibitory effect on rotavirus and the concentrations of IgA in human milk and serum samples.

Conclusion:

Anti‐rotavirus antibodies are only partly responsible for the neutralizing activity detected in milk and serum. This result suggests that other components possessing suppressive activity against rotavirus must also be present.
Usefulness of Nonbreath‐hold 1‐Shot Magnetic Resonance Cholangiopancreatography for the Evaluation of Choledochal Cyst in Children
Authors: Suzuki Mitsuyoshi , Shimizu Toshiaki , Kudo Takahiro , Suzuki Ryuyo , Ohtsuka Yoshikazu , Yamashiro Yuichiro , Shimotakahara Akihiko , Yamataka Atsuyuki
Published: May 2006

Objective:

The aim of this study was to clarify the usefulness of magnetic resonance cholangiopancreatography (MRCP) for the evaluation of choledochal cyst in children.

Subjects and methods:

MRCP was performed preoperatively in 33 patients. The MRCP findings were compared with those of endoscopic retrograde cholangiopancreatography or intraoperative cholangiopancreatography.

Results:

In all 33 patients, MRCP could detect choledochal cyst. The detection rate of a cyst in the main pancreatic duct was 62.2%, of abnormal union of the pancreaticobiliary junction (AUPBJ) was 53.3%, of dilatation or abnormalities of the main pancreatic duct was 75.0% and of a protein plug or stone was 76.9%. In patients under 2 years of age (group A), these findings were significantly lower than those of patients above 2 years of age (group B) [main pancreatic duct: 16.6% (1/6) vs 73.1% (19/26), P < 0.01; AUPBJ: 0.0% (0/6) vs 66.7% (16/24), P < 0.05; and protein plug or stone: 0.0% (0/2) vs 90.9% (10/11), P < 0.05]. The detection rate of AUPBJ in the patients with fusiform dilatation was superior to that of those with cystic dilatation [70% (14/20) vs 20% (2/10), P < 0.05]. In the patients with fusiform dilatation, the detection rate in group A was significantly lower than that in group B [0.0% (0/3) vs 82.4% (14/17), P < 0.01]; however, there was no significant difference between the 2 groups in the detection of cystic dilatation.

Conclusion:

In patients older than 2 years, MRCP should be the first‐choice method for confirming the diagnosis and for ensuring accurate visualization of the pancreaticobiliary system.
Probiotic Intervention in Neonates‐Will Permanent Colonization Ensue?
Authors: Gueimonde Miguel , Kalliomäki Marko , Isolauri Erika , Salminen Seppo
Published: May 2006

The presence of Lactobacillus rhamnosus GG at 6 and 12 months in the feces of 128 infants receiving the strain or placebo for 6 months after birth was monitored. No permanent establishment of the strain was found, but transient colonization was observed at 6 months of age. The presence of the strain at the end of the administration period was correlated with a reduced prevalence of atopic eczema later in life.
6‐Thioguanine‐related Chronic Hepatotoxicity and Variceal Haemorrhage in Children Treated for Acute Lymphoblastic Leukaemia‐A Dual‐centre Experience
Authors: Ravikumara Madhur , Hill Frank G.H. , Wilson David C. , Gillett Peter M. , Thomas Angela , Brown R. , Darbyshire Philip J. , McKiernan Patrick J.
Published: May 2006

Background:

6‐Thioguanine treatment in childhood acute lymphoblastic leukaemia (ALL) has been shown to cause hepatic veno‐occlusive disease, but this usually resolved with drug withdrawal. Recent reports suggested that treatment of ALL with 6‐thioguanine can lead to chronic hepatotoxicity and portal hypertension. We describe our experience from 2 UK centres of chronic hepatotoxicity in children receiving maintenance 6‐thioguanine for ALL in the national leukaemia protocol ALL 97/99.

Methods:

Retrospective review of children who were referred with liver disease secondary to 6‐thioguanine treatment of ALL was performed. A paediatric pathologist blinded to the clinical features reviewed liver histology slides.

Results:

Ten of 75 children (13%) treated with 6‐thioguanine in both centres were referred at a median of 6 months (range, 2‐29) after discontinuation of chemotherapy. In 8 cases, referral was due to persistent thrombocytopenia and splenomegaly. Two children presented with acute variceal bleeding. All had thrombocytopenia at referral, and ultrasonography showed coarse hepatic echo texture and splenomegaly in all. Endoscopy showed oesophageal varices in 7 and gastric varices in 1. Nine underwent liver biopsy that showed features compatible with nodular regenerative hyperplasia in 5 cases. After a median follow‐up of 36 months, a further child has had a variceal haemorrhage and all but 2 children remain thrombocytopenic.

Conclusions:

6‐Thioguanine‐induced chronic hepatotoxicity is a significant complication in children treated with this agent for ALL. Children may present several months to years after discontinuation of 6‐thioguanine. All children given maintenance treatment of ALL with this agent should be screened, and affected children require long‐term surveillance.
Changes of Gut Microbiota and Immune Markers During the Complementary Feeding Period in Healthy Breast‐fed Infants
Authors: Amarri S. , Benatti F. , Callegari M.L. , Shahkhalili Y. , Chauffard F. , Rochat F. , Acheson K.J. , Hager C. , Benyacoub J. , Galli E. , Rebecchi A. , Morelli L.
Published: May 2006

Introduction

Little is known about changes in intestinal microbiota during the important period of complementary feeding (weaning). This descriptive study investigated changes of selected gut microbiota and markers of gut permeability and the immune system in breast fed infants during the complementary feeding period.

Methods

22 healthy, exclusively breast fed infants (from birth to 4 months) with no antibiotic intake during the month prior to the study, were followed from 4 to 9 months of age. Faecal and saliva samples were collected at the start of the study (V0) and at monthly intervals (V1—V5) for measurement of selective gut microbiota (bifidobacteria, lactobacilli, vancomycin‐insensitive lactobacilli, enterobacteria, enterococci, Clostridium perfringens) using semi‐selective media. Immune markers (α‐1‐antitrypsin, eosinophil cationic protein (ECP), secretory IgA and TNF‐α were measured in saliva and secretory IgA and TNF‐α in faecal samples.

Results

High stool bifidobacteria counts at the start of the study (7.99 1 1.95 log10 CFU/g faeces) remained stable throughout the 5 months of complementary feeding while counts of enterobacteria and enterococci increased with age (P < 0.05 and P = 0.02 respectively). Vancomycin‐insensitive lactobacilli increased significantly during weaning from V0 to V3 (P < 0.01), and then decreased slightly (V4). Faecal Clostridium perfringens remained below the detection limit during the study and parameters measured in saliva did not change. Faecal ECP decreased significantly from 1.011.4 (V0) to 0.510.9 mg/mg protein (V5) P = 0.03.

Conclusion

Age and/or diet modifications during complementary feeding had no impact on faecal bifidobacteria counts but increased those of enterobacteria and enterococci. Transient increases in faecal lactobacilli and vancomycininsensitive lactobacilli counts were observed. The reduction in faecal ECP may indicate a decrease in gut permeability (reinforcement of gut mucosa integrity) during the weaning period with age.
Probiotics in Gastrointestinal Diseases in Children
Authors: Szajewska Hania , Setty Mala , Mrukowicz Jacek , Guandalini Stefano
Published: May 2006

The use of probiotics, once discussed primarily in the context of alternative medicine, is now entering mainstream medicine. However, only a few of the potential health benefits attributed to probiotics have been confirmed in well‐designed, well‐conducted, randomized, controlled trials. This is especially true in the pediatric population. We review here the available evidence on efficacy of probiotics in children in the prevention and treatment of gastrointestinal diseases. Although we restrict our analysis to the pediatric age, whenever potentially relevant information is available only from adult studies, they are examined as well. Probiotics have been most extensively studied in the treatment of diarrheal diseases, where their efficacy can be considered well established. Studies documenting effects in other childhood gastrointestinal illnesses are few, although some preliminary results are promising. Furthermore, only a limited number of probiotic strains have been tested, and, as the effects of different probiotic microorganisms are not equivalent, results cannot be generalized. Thus, at present, we have some positive certainties, lots of exciting promises and many unanswered questions.
Feeding Preterm Infants After Hospital Discharge
Authors:   ESPGHAN Committee on Nutrition:, Aggett Peter J. , Agostoni Carlo , Axelsson Irene , De Curtis Mario , Goulet Olivier , Hernell Olle , Koletzko Berthold , Lafeber Harry N. , Michaelsen Kim F. , Puntis John W.L. , Rigo Jacques , Shamir Raanan , Szajewska Hania , Turck Dominique , Weaver Lawrence T.
Published: May 2006

Survival of small premature infants has markedly improved during the last few decades. These infants are discharged from hospital care with body weight below the usual birth weight of healthy term infants. Early nutrition support of preterm infants influences long‐term health outcomes. Therefore, the ESPGHAN Committee on Nutrition has reviewed available evidence on feeding preterm infants after hospital discharge. Close monitoring of growth during hospital stay and after discharge is recommended to enable the provision of adequate nutrition support. Measurements of length and head circumference, in addition to weight, must be used to identify those preterm infants with poor growth that may need additional nutrition support. Infants with an appropriate weight for postconceptional age at discharge should be breast‐fed when possible. When formula‐fed, such infants should be fed regular infant formula with provision of long‐chain polyunsaturated fatty acids. Infants discharged with a subnormal weight for postconceptional age are at increased risk of long‐term growth failure, and the human milk they consume should be supplemented, for example, with a human milk fortifier to provide an adequate nutrient supply. If formula‐fed, such infants should receive special postdischarge formula with high contents of protein, minerals and trace elements as well as an long‐chain polyunsaturated fatty acid supply, at least until a postconceptional age of 40 weeks, but possibly until about 52 weeks postconceptional age. Continued growth monitoring is required to adapt feeding choices to the needs of individual infants and to avoid underfeeding or overfeeding.
Cytokine Tumor Necrosis Factor‐alpha A Promoter Gene Polymorphism at Position −308 G→A and Pediatric Inflammatory Bowel Disease
Authors: Sýkora Josef , Šubrt Ivan , Dìdek Petr , Siala Konrad , Schwarz Jan , Machalová Veronika , Varvařovská Jana , Pazdiora Petr , Pozler Oldrich , Stožický František
Published: May 2006

Objectives:

Our pilot study aimed to determine the effect of tumor necrosis factor‐alpha (TNF‐α) 308 G→A promoter single‐nucleotide polymorphism in pediatric inflammatory bowel disease (IBD), its influence on inflammatory activity and the clinical manifestations.

Methods:

We obtained genomic DNA from 164 subjects, 82 with long‐standing IBD aged 8 to 18 years: 46 with Crohn disease (CD) and 36 with ulcerative colitis (UC). Eighty‐two healthy children served as the control population. Genotyping was determined by using a restriction enzyme‐based assay. TNF‐α 308 G→A polymorphism was assessed in terms of inflammatory (C‐reactive protein [CRP]) and disease activity. The latter was assessed by the Pediatric Crohn's Disease Activity Index (PCDAI) and the Truelove index for CD and UC, respectively.

Results:

Significant differences in TNF‐α 308 A polymorphism were found between the IBD group and controls (P < 0.05) and the UC group and controls (P < 0.001). No differences were noted between TNF‐α 308 A polymorphism and clinical characteristics in UC. The frequency of the −308 A allele of TNF was not different in CD compared with that in the control group. The frequency of TNF‐α 308 A genotype was significantly higher in CD patients with predominantly stenosing/penetrating disease compared with patients without complications (P < 0.001) and healthy controls (P < 0.01). In CD patients, those carrying TNF −308 A had a significant increase in CRP (P < 0.05) and the PCDAI (P < 0.05). In CD, CRP levels strongly correlated with the PCDAI (r = 0.6150, P < 0.001). In UC, significant differences among the mean levels of CRP (P < 0.05) and disease activity (P < 0.001) related to TNF‐α 308 A polymorphism were found. Allele distribution (odds ratio, 12.9; CI, 1.18‐140.81, P < 0.001) and CRP serum levels (odds ratio, 1.020; CI, 1.00‐1.04, P < 0.001) were independently associated with CD complications.

Conclusions:

Although not necessarily dictating IBD initiation, the TNF‐α 308 A polymorphism may play a role in modifying the CD phenotype. The polymorphism may influence disease activity as well as more intense inflammatory activity in both forms of IBD and may modify the progression of chronic digestive tract inflammation.
Lung adenocarcinomas induced in mice by mutant EGF receptors foundin human lung cancers respondto a tyrosine kinase inhibitor orto down-regulation of the receptors
Authors: Politi Katerina , Zakowski Maureen F. , Fan Pang-Dian , Schonfeld Emily A. , Pao William , Varmus Harold E.
Published: May 2006

Somatic mutations in exons encoding the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene are found in human lung adenocarcinomas and are associated with sensitivity to the tyrosine kinase inhibitors gefitinib and erlotinib. Nearly 90% of theEGFRmutations are either short, in-frame deletions in exon 19 or point mutations that result in substitution of arginine for leucine at amino acid 858 (L858R). To study further the role of these mutations in the initiation and maintenance of lung cancer, we have developed transgenic mice that express an exon 19 deletion mutant (EGFRΔL747–S752) or the L858R mutant (EGFRL858R) in type II pneumocytes under the control of doxycycline. Expression of eitherEGFRmutant leads to the development of lung adenocarcinomas. Two weeks after induction with doxycycline, mice that express theEGFRL858Rallele show diffuse lung cancer highly reminiscent of human bronchioloalveolar carcinoma and later develop interspersed multifocal adenocarcinomas. In contrast, mice expressingEGFRΔL747–S752develop multifocal tumors embedded in normal lung parenchyma with a longer latency. With mice carrying eitherEGFRallele, withdrawal of doxycycline (to reduce expression of the transgene) or treatment with erlotinib (to inhibit kinase activity) causes rapid tumor regression, as assessed by magnetic resonance imaging and histopathology, demonstrating that mutantEGFRis required for tumor maintenance. These models may be useful for developing improved therapies for patients with lung cancers bearingEGFRmutations.
Depletion of serotonin selectively impairs short-term memory without affecting long-term memory in odor learning in the terrestrial slug Limax valentianus
Authors: Shirahata Takaaki , Tsunoda Makoto , Santa Tomofumi , Kirino Yutaka , Watanabe Satoshi
Published: May 2006

The terrestrial slug Limax is able to acquire short-term and long-term memories during aversive odor-taste associative learning. We investigated the effect of the selective serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) on memory. Behavioral studies indicated that 5,7-DHT impaired short-term memory but not long-term memory. HPLC (high-performance liquid chromatography) analysis revealed that 5,7-DHT significantly reduced serotonin content in the central nervous system. The present study suggests that acquisition, retention, and/or retrieval of short-term memory involves serotonin, and neither acquisition nor retrieval of long-term memory requires serotonin at a level as high as that required for short-term memory.
Repeated acquisitions and extinctions in classical conditioning of the rabbit nictitating membrane response
Authors: Kehoe E. James
Published: May 2006

The rabbit nictitating membrane (NM) response underwent successive stages of acquisition and extinction training in both delay (Experiment 1) and trace (Experiment 2) classical conditioning. In both cases, successive acquisitions became progressively faster, although the largest, most reliable acceleration occurred between the first and second acquisition. Successive extinctions were similar in rate. The results challenge contextual control theories of extinction but are consistent with attentional and layered-network models. The results are discussed with respect to their implications for the interaction between cerebellar and forebrain pathways for eyeblink conditioning.
Post-training intrahippocampal injection of synthetic poly-α-2,8-sialic acid-neural cell adhesion molecule mimetic peptide improves spatial long-term performance in mice
Authors: Florian Cédrick , Foltz Jane , Norreel Jean-Chrétien , Rougon Geneviève , Roullet Pascal
Published: May 2006

Several data have shown that the neural cell adhesion molecule (NCAM) is necessary for long-term memory formation and might play a role in the structural reorganization of synapses. The NCAM, encoded by a single gene, is represented by several isoforms that differ with regard to their content of α-2,8-linked sialic acid residues (PSA) on their extracellular domain. The carbohydrate PSA is known to promote plasticity, and PSA-NCAM isoforms remain expressed in the CA3 region of the adult hippocampus. In the present study, we investigated the effect on spatial memory consolidation of a PSA gain of function by injecting a PSA mimetic peptide (termed pr2) into the dorsal hippocampus. Mice were subjected to massed training in the spatial version of the water maze. Five hours after the last training session, experimental mice received an injection of pr2, whereas control mice received PBS or reverse peptide injections in the hippocampal CA3 region. Memory retention was tested at different time intervals: 24 h, 1 wk, and 4 wk. The results showed that the post-training infusion of pr2 peptide significantly increases spatial performance whenever it was assessed after the training phase. By contrast, administration of the control reverse peptide did not affect retention performance. These findings provide evidence that (1) PSA-NCAM is involved in memory consolidation processes in the CA3 hippocampal region, and (2) PSA mimetic peptides can facilitate the formation of long-term spatial memory when injected during the memory consolidation phase.
Effects of intra-amygdala infusion of CB1 receptor agonists on the reconsolidation of fear-potentiated startle
Authors: Lin Hui-Ching , Mao Sheng-Chun , Gean Po-Wu
Published: May 2006

The cannabinoid CB1 receptor has been shown to be critically involved in the extinction of fear memory. Systemic injection of a CB1 receptor antagonist prior to extinction training blocked extinction. Conversely, administration of the cannabinoid uptake inhibitor AM404 facilitated extinction in a dose-dependent manner. Here we show that bilateral infusion of CB1 receptor agonists into the amygdala after memory reactivation blocked reconsolidation of fear memory measured with fear-potentiated startle. The effect was dose-dependent and could be blocked by AM251, a specific CB1 receptor antagonist. In contrast, the effect of CB1 agonists on reconsolidation was no longer seen if memory reactivation was omitted. Concomitant with block of reconsolidation, CB1 agonist-treated animals did not exhibit shock-induced reinstatement or spontaneous recovery of fear. The absence of recovery was not attributable to permanent damage to the amygdala in WIN-treated rats, nor did the effect result from alteration of baseline startle or shock reactivity. These results suggest that CB1 agonists could impair fear memory via blocking reconsolidation.
Dishabituation in Aplysia can involve either reversal of habituation or superimposed sensitization
Authors: Hawkins Robert D. , Cohen Tracey E. , Kandel Eric R.
Published: May 2006

Dishabituation has been thought to be due either to reversal of the process of habituation or to a second process equivalent to sensitization superimposed on habituation. One way to address this question is by testing whether dishabituation and sensitization can be dissociated. Previous studies using this approach in Aplysia have come to different conclusions about the nature of dishabituation, perhaps because those studies differed in many respects, including (1) whether they also observed transient behavioral inhibition, and (2) whether they used test stimuli that activated the LE siphon sensory neurons or as yet unidentified sensory neurons. To attempt to resolve the apparent contradictions between the previous studies, we have explored the importance of these two factors by performing a parametric study of dishabituation and sensitization of gill withdrawal in a simplified preparation that does not exhibit transient behavioral inhibition, using two different test stimuli that are known to activate the LE (Touch) or unidentified (Not Touch) sensory neurons. We find that dishabituation and sensitization in this preparation have similar time courses and generally similar functions of shock intensity. However, under one condition, with the Not Touch stimulus 2.5 min after the shock, dishabituation has a reverse effect of shock intensity. Additional analyses suggest that dishabituation with the Not Touch stimulus 2.5 min after the shock is due to reversal of habituation, whereas 12.5 min after the shock, dishabituation is due to superimposed sensitization. These results thus suggest that dishabituation may involve either process in the same preparation, and begin to define the conditions that favor one or the other.
NT-3 facilitates hippocampal plasticity and learning and memory by regulating neurogenesis
Authors: Shimazu Kazuhiro , Zhao Mingrui , Sakata Kazuko , Akbarian Schahram , Bates Brian , Jaenisch Rudolf , Lu Bai
Published: May 2006

In the adult brain, the expression of NT-3 is largely confined to the hippocampal dentate gyrus (DG), an area exhibiting significant neurogenesis. Using a conditional mutant line in which the NT-3 gene is deleted in the brain, we investigated the role of NT-3 in adult neurogenesis, hippocampal plasticity, and memory. Bromodeoxyuridine (BrdU)-labeling experiments demonstrated that differentiation, rather than proliferation, of the neuronal precursor cells (NPCs) was significantly impaired in DG lacking NT-3. Triple labeling for BrdU, the neuronal marker NeuN, and the glial marker GFAP indicated that NT-3 affects the number of newly differentiated neurons, but not glia, in DG. Field recordings revealed a selective impairment in long-term potentiation (LTP) in the lateral, but not medial perforant path-granule neuron synapses. In parallel, the NT-3 mutant mice exhibited deficits in spatial memory tasks. In addition to identifying a novel role for NT-3 in adult NPC differentiation in vivo, our study provides a potential link between neurogenesis, dentate LTP, and spatial memory.
Composition and Morphology of Hydrated Tricalcium Silicate
Authors: GOTO SEISHI , DAIMON MASAKI , HOSAKA GIRO , KONDO RENICHI
Published: May 2006

Hardened C3S paste cured for 1 year at 20°C was examined to confirm the composition and the morphology of hydrated tricalcium silicate. A new technique was used in which the samples for scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were etched in 1% HNO3‐alcohol or in glycerol‐alcohol (4:6 by volume). After the surface was etched in 1% HNO3‐alcohol, SEM clearly showed the difference in texture in the outer and inner C‐S‐H products. The existence of a zonal texture within the inner C‐S‐H products was shown, in addition to the unreacted core; particles 0.1 to 0.2 μm in diameter were observed. After free CH extraction with glycerol‐alcohol, two new types of C‐S‐H grains could be identified. One type has a smooth surface, which seems to be produced from C3S grains trapped within the growing CH crystals in the early stage of hydration, the C/S mol ratio for these being >3. The other type is covered with many acicular outer C‐S‐H gel hydration products and has a C/S mol ratio >3.
A Theoretical Approach to Particle Trajectory in Mixed‐Flow Spray Dryers
Authors: GAVIOLI G. , PALMONARI C.
Published: May 2006

The trajectory of atomized droplets in a mixed‐flow spray dryer depends on the size and configuration of the drying chamber, the mode of introduction of the drying air, the location and number of nozzles, and the resultant spray pattern. Differential equations are used to represent the droplet trajectory and air pattern in a proposed method for predicting the distance traveled by individual ceramic particles in the dryer.
Determination of Biaxial Compressive Strength of a Sintered Alumina Ceramic
Authors: ADAMS MARC , SINES GEORGE
Published: May 2006

The compressive strength of commercial high‐density alumina was measured in several compressive biaxial stress states. The compressive strength was only slightly affected by the magnitude of the intermediate principal stress. The average value of the compressive strengths measured in all stress states, excluding the equibiaxial and the near‐uniaxial compressive stress states, was 528 ksi. The average of the coefficients of variation was 3%. The tensile strength measured for the material indicates that the ratio of compressive strength to tensile strength is ∼ 18.
Statistical Determination of Surface Flaw Density in Brittle Materials
Authors: MATTHEWS J. R. , McCLINTOCK F. A. , SHACK W. J.
Published: May 2006

The density of surface flaws in brittle materials can be determined from the loads in many different kinds of tests. A general method is derived and applied to indentation experiments on crown, plate, window, lead, and commercial heat‐resistant and heat‐absorbing glasses. Knowledge of flaw density is important for estimating size effect, and differences in flaw density indicate the possibility of significant improvements in strength by eliminating a few major sources of flaws.
Polyaxial Stress‐Strain Relations in ATJS Graphite
Authors: BATDORF S. B.
Published: May 2006

Theoretical considerations are applied to Jortner's experimental data in order to develop a simple analytical stress‐strain relation for ATJS graphite under arbitrary loading conditions. Since the relation proposed correlates well with the entire range of proportional loading encompassed by his data, it is reasonable to expect that the theoretical predictions of strains for stresses that are inaccessible in the laboratory will also be accurate. It is anticipated that, with minor changes hi the values of the theoretical parameters, the stress‐strain law will also apply to other transversely isotropic graphites.
Role of Copper Ions in Low‐Melting Solder Glasses
Authors: TAKAMORI TAKESHI , REISMAN ARNOLD , BERKENBLIT MELVIN
Published: May 2006

Controlled melting conditions for Cu‐containing solder glasses yielded a variety of Cu+/Cu2+ ratios from a single glass starting composition. Measurements of softening point, thermal expansion, chemical durability, plus chemical analysis revealed that the well‐known viscosity effect of adding copper oxide to solder glasses is caused primarily by the Cu+ ion; Cu2+ plays a minor role, if any.
Synthesis of Continuous Sic Fibers with High Tensile Strength
Authors: YAJIMA SEISHI , OKAMURA KIYOHITO , HAYASHI JOSABURO , OMORI MAMORU
Published: May 2006

Continuous Sic fibers with a tensile strength of 350 kg/mm2 and a Young's modulus of 30 tons/mm2 were synthesized from an organometallic polymer. Continuous fibers were first obtained by heat‐treating a polycarbosilane polymer which had been synthesized from dimethyldichlorosilane. The fiber, which contains ultrafine‐grain crystallites of β‐Sic, has no fiber texture measurable by X‐ray diffraction and high‐voltage electron microscopy.
Calculation of the Activation Energy of Solid‐State Reactions Using the Moessbauer Effect
Authors: EISSA N. A. , BAHGAT A. A. , MOHAMED A. H. , SALEH S. A.
Published: May 2006

Activation energies for the formation of Zn, Cd, and Ni ferrites were calculated from a series of Moessbauer spectra obtained during the formation process. These spectra were analyzed by 3 methods. The results showed that the Moessbauer effect can be used to follow the reaction kinetics.
Sintering of Covalent Solids
Authors: GRESKOVICH C. , ROSOLOWSKI J. H.
Published: May 2006

The sintering behavior of primarily covalently bonded β‐SiC, Si, and Si3N4 was studied using surface area and densification measurements as well as observations of microstructures developed during firing. The existence of highly dense, microscopic regions and large (≥100°) dihedral angles in fired compacts of β‐SiC and Si which experience little macroscopic densification suggests that macroscopic densification is not intrinsically limited by the effects of surface energy. The mechanism proposed to explain the microstructure that develops in unsinterable covalent solids which do not undergo a phase change is based on the existence of a high ratio of surface and/or vapor‐phase matter transport‐to‐volume and/or grain‐boundary transport. The addition of boron to both β‐SiC‐ and Si‐containing carbon retards surface and/or vapor‐phase transport and grain growth at lower temperatures, which results in enhanced densification at high temperatures. Macroscopic densification of β‐SiC and α‐Si3N4 can also be retarded by the formation of a continuous network of high‐aspect‐ratio grains of the polymorphic form that rigidities the sintering body. Finally, the sintering of pure Si depends sensitively on particle size in the submicron range. Nearly theoretical density is achieved in Si powder of ∼0.06‐μm size. This result suggests that other pure covalently bonded solids can also be sintered to high density without applied pressure.
Early Hydration of Tricalcium Silicate
Authors: TADROS M. E. , SKALNY JAN , KALYONCU R. S.
Published: May 2006

The hydration of tricalcium silicate (C3S) in the preacceleration stages was studied. The C3S particles carry a positive charge during the early stages of hydration. Following a rapid hydrolysis of C3S, calcium ions adsorbed on the Si‐rich surface of C3S particles, greatly reducing their further dissolution, thus initiating the induction period. The [Ca2+] and [OH‐] continue to increase at lower rates and, because Ca(OH)2 crystal growth is inhibited by silicate ions, become supersaturated with respect to Ca(OH)2. When the supersaturation reaches a value of ∼1.5 to 2.0 times the saturation concentration, nuclei are formed, and rapid growth of Ca(OH)2 and C‐S‐H is initiated. These products act as sinks for the ions in solution, thus enhancing the further dissolution of C3S.
Magnetic Properties of Anisotropic Lead Ferrite
Authors: ABRAMS J. C. , McLAREN M. G.
Published: May 2006

Oriented sintered compacts of PbO 5Fe2O3+ 0.3% B2O3 (as lead borate frit) were prepared. Green and sintered bulk density, sintered volume shrinkage, weight loss, residual induction, saturation magnetization, coercive force, intrinsic coercive force, and maximum energy product were determined. Experiments were statistically designed and each of the primary responses was subjected to analysis of variance to test for statistical significance. The highest magnetic energy product achieved from these experiments was 3.1 × 105 G‐Oe, a value which was within the specified ± 20% of the nominal value most often quoted for commercial barium ferrites. It was also determined that lead ferrite at theoretical density would have a maximum energy product of 4.1 to 4.5 × 106 G‐Oe.
Optical and X‐Ray Single Crystal Studies of the Monoclinic ⇌ Tetragonal Transition in ZrO2
Authors: BULJAN S. T. , McKINSTRY H. A. , STUBICAN V. S.
Published: May 2006

The monoclinic ⇌ tetragonal phase transition in ZrO2 single crystals was studied at temperature by transmission optical microscopy and X‐ray diffraction techniques. A series of timelapse photographs illustrated the relations between the events that occur during the transition. The events themselves were recognized by direct observation using a high‐temperature microscope stage and by scrutiny of several high‐temperature Laue photographs. During heating the monoclinic phase transforms to the tetragonal by the motion of an interface parallel to the (100)m plane; simultaneous twinning also occurs behind the advancing interface. The tetragonal phase is usually twinned on the (12)bct or (12)bct plane, and the extent of twinning is influenced by the heating rate. Cooling transforms the untwinned tetragonal form into a twinned monoclinic form with the orientation of the monoclinic twins parallel to the trace of the (001)m plane when observations are made in the (100)m plane. Transformation of a twinned tetragonal crystal results in twins on the {110}m and {001}m planes. Orientation relations in the ZrO2 transformation are: (100)m‖(110)bct, [010]m‖[001]bct, and by the virtue of twinning, (100)m‖(110)bct, [001]m‖[001]bct. During cooling the same topotaxial relations are maintained.
11B and 27Al Nuclear Quadrupole Interactions in SiO2‐B2O3‐Al2O3‐R2O Glass Systems
Authors: KOBAYASHI KEIJI , OKUMA HIDEO
Published: May 2006

Quadrupole interactions of 11B and 27Al in SiO2‐B2O3‐Al2O3‐R2O glass systems were investigated to determine the structure of these glasses, which should be amenable to chemical strengthening. The ratio of BO4 units to BO3 units approached unity as the R2O/Al2O3 ratio for compounds having fixed B2O3 contents approached unity. Nuclear quadrupole coupling constants (e2Qq/h=2.73 to 2.93 MHz) were measured for the NMR spectra of 11B triangles. The line shapes of 27Al spectra varied with chemical composition, but a few glasses exhibited 27Al line shapes similar to those of the AlO4 triclusters in SiO2‐Al2O3‐Na2O glasses. Compositional trends in the formation of BO4 and AlO4 were deduced from the NMR spectra.
Mullite Development from Fibrous Kaolin Mineral
Authors: CAMPOS TERESA W. , SANTOS HELENA DE SOUZA , SANTOS PERSIO DE SOUZA
Published: May 2006

The development of mullite from kaolin minerals was studied using transmission electron microscopy and X‐ray powder diffraction methods on the unusual long‐fibered kaolin from Piedade, Sao Paulo, Brazil. The mullite crystals observed at ≥ 1200°C initially exhibited an elliptical shape and were randomly oriented inside the tubes; at 1250°C their shape changed to laths oriented either parallel to the tube length or at 120° to the adjacent lath. At 1300°C, the shape changed to a bipointed lath and the crystals developed a hexagonal configuration with preferred orientation at 120°, similar to mullite developed from kaolinite plates. Thus, the temperature at which mullite begins to develop from this tubular kaolin is ∼200°C above that normally observed in well‐crystallized kaolinites and is 100°C above b axis disordered kaolinite. Cristobalite was not observed in the electron microscope in the range 1000° to 1300°C.
Ionic Conductivity of Li4SiO4, Li4GeO4, and Their Solid Solutions
Authors: HODGE IAN M. , INGRAM MALCOLM D. , WEST ANTHONY R.
Published: May 2006

Conductivity was measured for Li4SiO4 and its solid solutions with Li4GeO4 over a wide frequency range to separate clearly the effects of electrode polarization, conductance relaxations, etc., and to obtain true “dc” conductivities. The conductivities of all the electrolytes are markedly temperature‐dependent, ranging from 10−8 to 10−10Ω−1 cm−1 at 100°C to 10−2 to 1010Ω−1 cm−1 at 700°C. For solid solutions with the Li4GeO4 structure, conductivities fit the Arrhenius equation over a wide temperature range, but at higher temperatures a change in activation energy occurs, corresponding to a first‐order phase transition. In contrast, solid solutions with the Li4SiO4 structure show changes in activation energy which do not correspond to phase transitions, but which appear to indicate changes in the conduction mechanism.
Is Country Diversification better than Industry Diversification?
Authors: Hargis Kent , Mei Jianping
Published: May 2006

In this paper, we develop a framework in which one can examine the source of industry and country diversification by examining their underlying return components. We find that the global cash flow factor explains on average 39% of the variation of country cash flows and global discount rates explain 55% of the variation of country discount rates. These are much less than the explanatory power of the two factors over industry cash flow and discount rate variations, which are 72% and 78% respectively. This suggests that global factors are much less important for return components at country level than at the industry level. As a result, both better diversification of expected returns and cash flows across countries determine the larger benefits of country diversification versus industry diversification. Moreover, emerging markets tend to have much smaller co‐movements of both dividends and expected returns with those of the world, suggesting a lower degree of integration with the world goods and financial markets. Our results cast doubt on the prevailing wisdom that country diversification should be replaced by industry diversification.
The Importance of Industry and Country Effects in the EMU Equity Markets
Authors: Ferreira Miguel Almeida , Ferreira Miguel Ângelo
Published: May 2006

Most empirical studies find that country effects are larger than industry effects in stock returns, although industry effects have gained in importance recently. Our results support the dominance of country effects relative to industry and common effects in the EMU equity markets in the 1975–2001 period. However, there is an increasing importance of industry effect relative to country effect in the 1990s. In fact, industry effects is similar in magnitude to country effect in the post‐euro period. The evolution of the ratio of country to industry effect is explained by the decrease in the cross‐sectional variance of interest rate movements across EMU countries. Thus, there is evidence that nominal convergence has reduced the differences between national equity markets.
Herding in the German Mutual Fund Industry
Authors: Walter Andreas , Moritz Weber Friedrich
Published: May 2006

This paper analyses the trading activity of German mutual funds in the 1998–2002 period to investigate whether German mutual fund managers are engaged in herding behaviour. Another objective of the study is to determine the impact of this herd‐like trading on stock prices. Our results provide evidence of herding and positive feedback trading by German mutual fund managers. We show that a significant portion of herding detected in the German market is associated with spurious herding as a consequence of changes in benchmark index composition. Investigating the impact of mutual fund herding on stock prices, we find that herding seems to neither destabilise nor stabilise stock prices.
Why and How UK Firms Hedge
Authors: Judge Amrit
Published: May 2006

This paper attempts to differentiate among the theories of hedging by using disclosures in the annual reports of 400 UK companies and data collected via a survey. I find, unlike many previous US studies, strong evidence linking the decision to hedge and the expected costs of financial distress. The tests show that this is mainly because my definition of hedging includes all hedgers and not just derivative users. However, when the tests employ the same hedging definition as previous US studies, financial distress cost factors still appear to be more important for this sample than samples of US firms. Therefore, a secondary explanation for the strong financial distress results might be due to differences in the bankruptcy codes in the two countries, which result in higher expected costs of financial distress for UK firms. The paper also examines the determinants of the choice of hedging method distinguishing between non‐derivative and derivatives hedging. My evidence shows that larger firms, firms with more cash, firms with a greater probability of financial distress, firms with exports or imports and firms with more short‐term debt are more likely to hedge with derivatives. Thus, differences in opportunities, in incentives for reducing risk and in the types of financial price exposure play an important role in how firms hedge their risks.