bluuebunny/crossref_metadata_2025 huggingface dataset:
A Prospective 1‐Year Clinical and Radiographic Study of Implants Placed after Maxillary Sinus Floor Augmentation with Synthetic Biphasic Calcium Phosphate or Deproteinized Bovine Bone
Authors: Lindgren Christer , Mordenfeld Arne , Hallman Mats
Published: May 2010

Background: The technique of using bone grafts or different biomaterials for augmentation of the maxillary sinus prior to implant placement is well accepted by clinicians. However, clinical documentation of some bone substitutes is still lacking.

Purpose: This prospective study was designed to evaluate the success rate of implants placed after maxillary sinus augmentation with a novel synthetic biphasic calcium phosphate (BCP) or deproteinized bovine bone (DBB), the latter acting as control.

Material and Methods: Nine edentulous patients and two partially edentulous patients with a mean age of 67 years with a bilateral need for sinus augmentation, <5 mm residual bone in the floor of the sinus and a crestal width ≥4 mm, were included in the study. After bilateral elevation of the Schneiderian membrane, all patients were randomized for augmentation with synthetic BCP in one side and DBB in the contralateral side. After 8 months of graft healing, 62 implants with an SLActive surface were placed. Implant survival, graft resorption, plaque index, bleeding on probing, sulcus bleeding index, probing pocket depth, and implant success rate were evaluated after 1 year of functional loading.

Results: After a mean of 118 days, all patients received their fixed prosthetic constructions. One implant was lost in each biomaterial, giving an overall survival rate of 96.8%. Success rates for implants placed in BCP and DBB were 91.7 and 95.7%, respectively. No significant difference in marginal bone loss was found around implants placed in BCP, DBB, or residual bone, respectively. The mean graft resorption was 0.43 mm (BCP) and 0.29 mm (DBB).

Conclusion: In this limited study, implant success rate was not dependent on the biomaterial used for maxillary sinus augmentation. Similar results were found after 1 year of functional loading for implants placed after sinus augmentation using BCP or DBB.
Maxillary Sinus Augmentation Using Prehydrated Corticocancellous Porcine Bone: Hystomorphometric Evaluation after 6 Months
Authors: Barone Antonio , Ricci Massimiliano , Covani Ugo , Nannmark Ulf , Azarmehr Iman , Calvo‐Guirado Josè Luis
Published: May 2010

Background: Insufficient alveolar bone height often prevents the placement of standard dental implants in the posterior part of edentulous maxilla. In order to increase adequately the vertical dimension of the reabsorbed alveolar process, a sinus lift procedure is often necessary. The aim of this study was to evaluate histologic results of a prehydrated corticocancellous porcine bone used in maxillary sinus augmentation.

Methods: Patients (age 18–70 years) with a residual bone height requiring a maxillary sinus augmentation procedure to place dental implants were eligible for this study. All patients were treated with the same surgical technique consisting of sinus floor augmentation via a lateral approach. The space obtained by elevation of the mucosa wall was grafted with prehydrated and collagenated corticocancellous porcine bone. Biopsies were harvested 6 months after the augmentation procedures.

Results: Twenty‐four patients were enrolled. The mean percentage of new formed bone was 43.9 ± 18.6% (range 7.5–100%), whereas the mean percentage of residual graft material was 14.2 ± 13.6% (range 0–41.9%). The new bone/residual graft material ratio in the maxillary sinuses was 3.1. The mean soft tissues percentage was 41.8 ± 22.7% (range 0–92.5%).

Conclusion: The present study suggested that porcine bone showed excellent osteoconductive properties and could be used successfully for sinus augmentation. Moreover, the porcine bone showed a high percentage of reabsorption after 6 months; this might be because of the presence of collagen and the porosity of the graft material.
Histomorphometrical Analysis following Augmentation of Infected Extraction Sites Exhibiting Severe Bone Loss and Primarily Closed by Intrasocket Reactive Soft Tissue
Authors: Mardinger Ofer , Vered Marilena , Chaushu Gavriel , Nissan Joseph
Published: May 2010

Background: Intrasocket reactive soft tissue can be used for primary closure during augmentation of infected extraction sites exhibiting severe bone loss prior to implant placement. The present study evaluated the histological characteristics of the initially used intrasocket reactive soft tissue, the overlying soft tissue, and the histomorphometry of the newly formed bone during implant placement.

Materials and Methods: Thirty‐six consecutive patients (43 sites) were included in the study. Extraction sites demonstrating extensive bone loss on preoperative periapical and panoramic radiographs served as inclusion criteria. Forty‐three implants were inserted after a healing period of 6 months. Porous bovine xenograft bone mineral was used as a single bone substitute. The intrasocket reactive soft tissue was sutured over the grafting material to seal the coronal portion of the socket. Biopsies of the intrasocket reactive soft tissue at augmentation, healed mucosa, and bone cores at implant placement were retrieved and evaluated.

Results: The intrasocket reactive soft tissue demonstrated features compatible with granulation tissue and long junctional epithelium. The mucosal samples at implant placement demonstrated histopathological characteristics of keratinized mucosa with no residual elements of granulation tissue. Histomorphometrically, the mean composition of the bone cores was – vital bone 40 ± 19% (13.7–74.8%); bone substitute 25.7 ± 13% (0.6–51%); connective tissue 34.3 ± 15% (13.8–71.9%).

Conclusions: Intrasocket reactive soft tissue used for primary closure following ridge augmentation is composed of granulation tissue and long junctional epithelium. At implant placement, clinical and histological results demonstrate its replacement by keratinized gingiva. The histomorphometrical results reveal considerable bone formation. Fresh extraction sites of hopeless teeth demonstrating chronic infection and severe bone loss may be grafted simultaneously with their removal.
Factors Associated with Failure of Surface‐Modified Implants up to Four Years of Function
Authors: Cosyn Jan , Vandenbulcke Edward , Browaeys Hilde , Van Maele Georges , De Bruyn Hugo
Published: May 2010

Objectives: The relative impact of innovative treatment concepts on the failure of surface‐modified implants is not well understood. This retrospective study aimed to explore this using data obtained in a university postgraduate training center.

Material and Methods: Patients treated with implants for a variety of indications over a 3‐year period were included. All implants had been at least 1 year in function. Clinical records were evaluated for implant failure and in reference to implant length/diameter/location, time from tooth loss to implant placement, bone condition (native/grafted), surgical protocol (two‐/one‐stage), loading protocol (delayed/early/immediate), type of prosthesis (removable/fixed), surgeon's experience level (resident/trainee) and specialty (periodontist/oral surgeon). The impact of each covariate on failure was tested using the Fisher's exact test. Kaplan‐Meier survival functions were constructed and Mantel‐Cox log–rank tests were used to compare survival functions. To correct for possible interaction, Cox proportional Hazards regression was adopted.

Results: Forty‐one of 1,180 (3.5%) implants were lost in 34/461 (7.4%) patients (245 ♀, 216 ♂; mean age 51, range 18–90). Factors showing significant impact on failure on the basis of univariate analyses were implant location (p = .015), surgical protocol (p = .002), loading protocol (p = .002), surgeon's experience level (p = .035) and specialty (p = .001). When controlling for other covariates, only the loading protocol had a significant influence (p = .049) with early loading more prone to failure (p = .014) when compared with delayed loading. Immediate loading and delayed loading showed comparable implant survival (p = .311).

Conclusions: Implant therapy may be highly successful in a training center where inexperienced clinicians are strictly monitored and personally guided. Implant specific variables do not affect implant survival but early loading is a risk indicator for implant failure, whereas immediate loading is not.
Single Implant Treatment in Healing versus Healed Sites of the Anterior Maxilla: A Clinical and Radiographic Evaluation
Authors: Eghbali Aryan , De Bruyn Hugo , De Rouck Tim , Cleymaet Roberto , Wyn Iris , Cosyn Jan
Published: May 2010

Purpose: The aim was to document the Nobelreplace tapered TiUnite® (Nobel Biocare, Göteborg, Sweden) implant system used by experienced clinicians in daily practice for replacing single maxillary anterior teeth and to compare the clinical and radiographic outcome between implants installed in healing sites (early implant placement) and fully healed sites (conventional implant placement) after on average two and a half years of function.

Material and Methods: A cross‐sectional study in patients who had been treated by two periodontists and two prosthodontists in 2006 and 2007 was conducted. Surgical treatment involved standard flap elevation without releasing incisions and restorative procedures included cemented crowns in all patients. Only straightforward single implant treatments in healing sites (6–8 weeks following tooth extraction) and fully‐healed sites (≥6 months following tooth extraction) were considered with both neighboring teeth present and without the need for hard and/or soft tissue grafting. Clinical and radiographic analyses of all implants were performed by a blinded clinician who had not been involved in the treatment.

Results: Forty‐nine of the 53 eligible single implants (22 early and 27 conventionally placed implants) in 44/48 patients were available for scrutiny. There was no significant difference in implant survival between early (95%) and conventionally (93%) installed implants (p = 1.000). Mean bone level to the implant‐abutment interface was 1.25 and 1.02 mm for early and conventional implant placement, respectively (p = .220). In spite of fairly low plaque levels (26%), overall peri‐implant bleeding was quite prevalent (36%). Mean peri‐implant probing depth was 3.3 mm. Five restorations had experienced technical complications.

Conclusions: Single Nobelreplace tapered TiUnite® implants installed in healing as well as in healed sites of the anterior maxilla are predictable. Both strategies seem equally successful in terms of implant survival, bone remodeling, clinical response, and risk for complications.
The Statistical Analysis of Judicial Decisions and Legal Rules with Classification Trees
Authors: Kastellec Jonathan P.
Published: May 2010

A key question in the quantitative study of legal rules and judicial decision making is the structure of the relationship between case facts and case outcomes. Legal doctrine and legal rules are general attempts to define this relationship. This article summarizes and utilizes a statistical method relatively unexplored in political science and legal scholarship—classification trees—that offers a flexible way to study legal doctrine. I argue that this method, while not replacing traditional statistical tools for studying judicial decisions, can better capture many aspects of the relationship between case facts and case outcomes. To illustrate the method's advantages, I conduct classification tree analyses of search and seizure cases decided by the U.S. Supreme Court and confession cases decided by the courts of appeals. These analyses illustrate the ability of classification trees to increase our understanding of legal rules and legal doctrine.
An autoinhibitory effect of the homothorax domain of Meis2
Authors: Hyman‐Walsh Cathy , Bjerke Glen A. , Wotton David
Published: May 2010

Myeloid ecotropic insertion site (Meis)2 is a homeodomain protein containing a conserved homothorax (Hth) domain that is present in all Meis and Prep family proteins and in the Drosophila Hth protein. The Hth domain mediates interaction with Pbx homeodomain proteins, allowing for efficient DNA binding. Here we show that, like Meis1, Meis2 has a strong C‐terminal transcriptional activation domain, which is required for full activation of transcription by homeodomain protein complexes composed of Meis2 and Pbx1. We also show that the activity of the activation domain is inhibited by the Hth domain, and that this autoinhibition can be partially relieved by the interaction of Pbx1 with the Hth domain of Meis2. Targeting of the Hth domain to DNA suggests that it is not a portable trans‐acting repression domain. However, the Hth domain can inhibit a linked activation domain, and this inhibition is not limited to the Meis2 activation domain. Database searching reveals that the Meis3.2 splice variant, which is found in several vertebrate species, disrupts the Hth domain by removing 17 codons from the 5′‐end of exon 6. We show that the equivalent deletion in Meis2 derepresses the C‐terminal activation domain and weakens interaction with Pbx1. This work suggests that the transcriptional activity of all members of the Meis/Prep Hth protein family is subject to autoinhibition by their Hth domains, and that the Meis3.2 splice variant encodes a protein that bypasses this autoinhibitory effect.

Structured digital abstract

 MINT‐7718353, MINT‐7718083, MINT‐7718172, MINT‐7718256, MINT‐7718300, MINT‐7718330: Meis2d (uniprotkb:O14770‐4) physically interacts (MI:0915) with PBX1 (uniprotkb:P40424) by anti tag coimmunoprecipitation (MI:0007)

 MINT‐7718110: Meis2e (uniprotkb:O14770‐5) physically interacts (MI:0915) with PBX1 (uniprotkb:P40424) by anti tag coimmunoprecipitation (MI:0007)
Evaluation of autologous bone marrow‐derived nucleated cells for healing of full‐thickness skin wounds in rabbits
Authors: Borena BM , Pawde AM , Amarpal  , Aithal HP , Kinjavdekar P , Singh Rajendra , Kumar Dinesh
Published: May 2010

The aim of the study was to evaluate the potential of autologous bone marrow‐derived nucleated cells to enhance the rate of healing of full‐thickness excisional skin wounds in rabbits. The study was conducted on 20 New Zealand white rabbits of either sex. Two, 2 × 2 cm full‐thickness skin (thoracolumabar region) excisional wounds were created; one on each side of the dorsal midline in each animal. The wounds were randomly assigned to either injection of autologous bone marrow‐derived nucleated cells into the wound margins (BI), or topical application of sterile saline solution (normal saline, NS), which served as control. The wound healing was assessed by evaluation of granulation tissue formation, wound contraction, epithelisation and histopathological and histochemical changes up to 28 days after creation of the wound. Granulation tissue appeared significantly faster in BI‐treated wounds (3.22 ± 0.22 days) than in NS‐treated wounds (4.56 ± 0.47 days). Better epithelisation was seen histologically in BI wounds than in NS‐treated wounds. Wound contraction was significantly more in BI wounds when compared with NS wounds on 21 post‐surgery. Histopathological examination of the healing tissue showed early disappearance of inflammatory reaction, significantly more neovascularisation, and more fibroplasias and early lay down and histological maturation of collagen in BI wounds than in control wounds. It was concluded that injection of autologous bone marrow‐derived nucleated cells in the wound margins induced faster and better quality healing of excisional skin wounds in rabbits when compared with normal saline. The injection of autologous bone marrow‐derived nucleated cells can be used to promote healing of large full‐thickness skin wounds in rabbits.
Corpus Cavernosal Smooth Muscle Relaxation Effect of a Novel AMPK Activator, Beta-Lapachone
Authors: Bae Jae Hyun , Kim Jin Wook , Kweon Gi Ryang , Park Myoung Gyu , Jeong Kyeong-Hoon , Kim Je Jong , Moon Du Geon
Published: May 2010

Introduction

Adenosine monophosphate-activated protein kinase (AMPK) activation is suggested to relax smooth muscle by endothelial nitric oxide synthase (eNOS) phosphorylation.

Aim

To assess the mechanism and effect of a novel AMPK activator, beta-lapachone, upon cavernosal smooth muscle relaxation and the therapeutic potential for erectile dysfunction.

Methods

Human umbilical vein endothelial cells (HUVECs) were treated with beta-lapachone. The lysates were blotted with specific antibodies for phosphorylated AMPK (p-AMPK) or phosphorylated eNOS (p-eNOS). The membranes were re-blotted for total AMPK total eNOS, or beta-actin. The eNOS activity was measured by the conversion of L-14C-arginine to L-14C-citrulline in HUVECs lysates. In a separated experiment, cavernosal strips from New Zealand white rabbits were harvested for organ bath study and the relaxation effect of beta-lapachone on phenylephrine-induced contracted strips was evaluated and compared with sodium nitroprusside, zaprinast, metformin, and aminoimidazole carboxamide ribonucleotide (AICAR). Methylene blue and L-NAME were used to assess the inhibition of cyclic guanosine monophosphate/nitric oxide pathway. Zinc-protoporphyrin-IX (ZnPP) was also used to investigate the contribution of mevalonate pathway.

Main Outcome Measures

The expression of p-AMPK, p-eNOS, AMPK and eNOS induced by beta-lapachone in HUVECs study and the percent relaxation of cavernosal tissue in organ bath study.

Results

Beta-lapachone clearly induced AMPK phosphorylation and, as a consequence, eNOS phosphorylation in HUVECs. Beta-lapachone-induced upregulation of eNOS activity was also observed in HUVECs and steadily increased up to 1 hour. In organ bath study, beta-lapachone significantly relaxed the phenylephrine pretreated strips in a dose-dependent manner. This relaxation effect was not totally blocked by methylene blue or L-NAME. After removing endothelium, the relaxation was totally blocked by ZnPP.

Conclusions

A novel AMPK activator, beta-lapachone has a strong relaxation effect on precontracted cavernosal smooth muscle strips in the rabbit. And phosphorylation of AMPK and eNOS strongly related to the action of beta-lapachone. Mevalonate pathway also might be considered as a suggestive mechanism.
Survivorship care after breast cancer: Follow‐up practices of Australian health professionals and attitudes to a survivorship care plan
Authors: BRENNAN Meagan E , BUTOW Phyllis , SPILLANE Andrew J , BOYLE Frances M
Published: May 2010

Objective:  The increasing number of breast cancer survivors and the complexity of follow‐up care make the provision of high‐quality survivorship care a challenge. This study explored the follow‐up practices of health professionals and their attitudes to alternative models such as shared care and the use of a survivorship care plan.

Methods:  Specialist oncologists (surgeons, medical and radiation oncologists) breast physicians and breast‐care nurses completed an online survey.

Results:  A total of 217 practitioners completed the survey, which was estimated to include 42.8% of oncologists treating breast cancer in Australia. One‐third of responding specialists reported spending more than 25% of their clinical time providing follow‐up care. They reported many positive aspects to follow‐up consultations and viewed follow‐up care as an important part of their clinical role but expressed concern about the sustainability of follow‐up care in their practices. The follow‐up intervals and recommendations were in line with national guidelines. The specialists were supportive of sharing follow‐up care with primary‐care physicians, breast physicians and breast‐care nurses. Most professionals felt that a survivorship care plan would improve care and said they would use a proforma.

Conclusion:  The oncologists felt that follow‐up care was an important part of their role and they were supportive of the concepts of shared care programs and a survivorship care plan. Input from consumers is required to evaluate the acceptability of these alternative models and to assess ways of implementing these changes to work towards a more comprehensive and sustainable method of delivering survivorship care.
Habitat Use by Sympatric Jaguars and Pumas Across a Gradient of Human Disturbance in Belize
Authors: Foster Rebecca J. , Harmsen Bart J. , Doncaster C. Patrick
Published: May 2010

Jaguars (Panthera onca) and pumas (Puma concolor) are sympatric across the entire jaguar range, where they coexist in increasingly fragmented landscapes under threat of persecution mainly in response to livestock predation. Pumas are known to inhabit a greater variety of natural habitats than jaguars, but little is known about the influence of anthropogenic factors on the coexistence of these two similar‐sized cats. This study compares habitat use of jaguars and pumas in Belize, Central America, using 1380 jaguar and puma photo captures from 3 yr of camera trapping, comprising 64–74 individual jaguars and an unknown number of pumas. Jaguars and pumas did not differ in their use of a large block of relatively homogenous secondary rain forest. However, pumas were scarce outside this forest block, whereas jaguars were detected throughout the human‐influenced landscape. Reasons for this discrepancy may include differential tolerance to human disturbance, and resource limitation for pumas outside the forest block. Intra‐specific variation in jaguar activity in the form of sex‐dependent habitat use was detected across the landscape. Male jaguars were detected at more locations than female jaguars and more frequently at each location, with a declining difference from a 50‐fold greater detection in the protected forest, through forest buffer, savannah, pastures, to negligible difference in the disturbed forest.
PREFERENCE FOR ONE OF TWO IDENTICAL STIMULI: EXPECTATIONS, EXPLICIT INSTRUCTIONS AND PERSONAL TRAITS
Authors: CHAPMAN KATHRYN W. , LOVELACE EUGENE , CARDELLO ARMAND , LAWLESS HARRY T.
Published: May 2010

Most consumers, given two identical food samples, express a preference for one, rather than choosing a no‐preference option. The stability and potential causes of this seemingly irrational preference were examined across three trials under different conditions, specifically, when the first test pair was identical or different, and when participants were explicitly told that the pairs would often be identical. Choice of no preference typically increased from the first to second trial, especially for groups who saw a pair of different samples on the first trial. The explicit instruction that samples might be the same failed to reduce expressing a preference on the initial trial although it had some effect on later trials. Analysis, by individuals, of sequences of preference or no‐preference responses across trials support independence of sequential responses and argue against stable personal traits as a predictor of preference choice.

PRACTICAL APPLICATIONS

More research needs to be done to understand the origins and operation of biases in preference tests. When tested under conditions in which the samples differ only slightly, participants tend to avoid the no‐preference option. This is potentially important when interpreting the results of preference tests and assigning practical significance to their outcomes. Also, single trial testing may produce somewhat different results from multi‐trial testing, the latter allowing for examination of effects of variation in recent experience.
Toward the Discovery of New Agents Able to Inhibit the Expression of Microsomal Prostaglandin E Synthase‐1 Enzyme as Promising Tools in Drug Development
Authors: De Simone Rosa , Andrés Rosa M. , Aquino Maurizio , Bruno Ines , Guerrero María D. , Terencio María C. , Paya Miguel , Riccio Raffaele
Published: May 2010

In our recent studies, we focused our attention on the synthesis of several γ‐hydroxybutenolides designed on the basis of petrosaspongiolide M 1 (PM) structure that has been recognized to potently inhibit the inflammatory process through the selective PLA2 enzyme inhibition. By means of a combination of computational methods and efficient synthetic strategies, we generated small collections of PM modified analogs to identify new potent PLA2 inhibitors, suitable for clinical development. In the course of the biological screening of our compounds, we discovered a potent and selective inhibitor of mPGES‐1 expression, the benzothiophene γ‐hydroxybutenolide 2, which so far represents the only product, together with resveratrol, able to reduce PGE2 production through the selective downregulation of mPGES‐1 enzyme. In consideration that microsomal prostaglandin E synthase 1 (mPGES‐1) is one of the most strategic target involved both in inflammation and in carcinogenesis processes, we decided to explore the biological effects of some structural changes of the γ‐hydroxybutenolide 2, hoping to improve its biological profile. This optimization process led to the identification of three strictly correlated compounds 14g, 16g, and 18 with higher inhibitory potency on PGE2 production on mouse macrophage cell line RAW264.7 through the selective modulation of mPGES‐1 enzyme expression.
Chemotherapeutic Effect of Calcidiol Derivative B3CD in a Neuroblastoma Xenograft Model
Authors: Lange Thilo S. , Zou Yongping , Singh Rakesh K. , Kim Kyu K. , Kristjansdottir Katrin , Sholler Giselle L. S. , Brard Laurent
Published: May 2010

Bromoacetoxy‐calcidiol (B3CD), a pro‐apoptotic and cytotoxic agent in neuroblastoma (NB) cell lines, displayed therapeutic potential in vivo as an anticancer drug in a NB xenograft mouse model. Tumors of all animals treated intraperitoneally with B3CD went into regression within 10–30 days of treatment, while tumors in control animals grew aggressively. The response mechanisms of NB cells to B3CD in vitro were studied and included differential targeting of cell cycle key regulators p21 and cyclin D1 on the transcriptional and expression level leading to arrest in G0/G1 phase. In contrast to the effect in ovarian cancer cells, B3CD‐induced cell death in SMS‐KCNR NB cells was only marginally mediated by the p38 MAPK signaling pathway. Signaling induced by exogenous recombinant EGF leads to a partial restoration of the negative effects of B3CD on SMS‐KCNR cell proliferation and survival. Upon combinational treatment of SMS‐KCNR cells with B3CD and recombinant EGF, the EGF receptor (EGF‐R) was highly activated. We suggest future studies to include analysis of the effects of B3CD in combination therapy with pharmacological inhibitors of cell cycle regulators or with EGF‐R‐targeting inhibitors, ‐toxins or ‐antibodies in vitro and their translation into in vivo models of tumor development.
Relationships between landforms, soils and vegetation in the River Plate coastal plain, Argentina
Authors: Giménez Jorge E. , Hurtado Martín A. , Kalesnik Fabio , Martínez Omar R.
Published: May 2010

The River Plate coastal plain is a 160‐km‐long, 3–10‐km‐wide strip, located to <5 m a.s.l. on the right bank of the estuary. It is formed by sediments and landforms generated by the littoral transport and marine ingressions and regressions during the Holocene. The coastal plain faces heavy pressures from Buenos Aires Metropolitan Area, with about 13 million inhabitants, industrial, mining and rural activities. Here, we analyse the relations existing between landforms, soils and vegetation. Despite the anthropogenic influence, the natural landscape is more or less preserved in some areas, such as patches of the southernmost gallery forest in the world in natural levees, the xerophytic forests located in well‐drained soils of beach ridges and other units such as Inland and Coastal Mudflats with wetland soils and vegetation, Tidal Flats with contrasting soils and plant communities among others.
British Society of Haematology, Slide Session presented at the Annual Scientific Meeting, Brighton 2009
Authors: McLORNAN D. P. , BURTHEM J. , DUNCOMBE A. , HATTON C. , HUTCHINSON C. V. , MARSDEN K. , MACARTNEY C. M. , SMITH‐STRANEY T. , UPRICHARD J. , WALLIS J. , WEBB S. , WILKINS B. S. , McMULLIN M. F.
Published: May 2010

Seven cases were discussed by an expert panel at the 2009 Annual Scientific Meeting of the British Society of Haematology. These cases are presented in a similar format to that adopted for the meeting. There was an initial discussion of the presenting morphology, generation of differential diagnoses and then, following display of further presenting and diagnostic information, each case was concluded with provision of a final diagnosis.
Electrical and chemical synapses between relay neurons in developing thalamus
Authors: Lee Seung‐Chan , Cruikshank Scott J. , Connors Barry W.
Published: May 2010

Gap junction‐mediated electrical synapses interconnect diverse types of neurons in the mammalian brain, and they may play important roles in the synchronization and development of neural circuits. Thalamic relay neurons are the major source of input to neocortex. Electrical synapses have not been directly observed between relay neurons in either developing or adult animals. We tested for electrical synapses by recording from pairs of relay neurons in acute slices of developing ventrobasal nucleus (VBN) of the thalamus from rats and mice. Electrical synapses were common between VBN relay neurons during the first postnatal week, and then declined sharply during the second week. Electrical coupling was reduced among cells of connexin36 (Cx36) knockout mice; however, some neuron pairs remained coupled. This implies that electrical synapses between the majority of coupled VBN neurons require Cx36 but that other gap junction proteins also contribute. The anatomical distribution of a β‐galactosidase reporter indicated that Cx36 was expressed in some VBN neurons during the first postnatal week and sharply declined over the second week, consistent with our physiological results. VBN relay neurons also communicated via chemical synapses. Rare pairs of relay neurons excited one another monosynaptically. Much more commonly, spikes in one relay neuron evoked disynaptic inhibition (via the thalamic reticular nucleus) in the same or a neighbouring relay neuron. Disynaptic inhibition between VBN cells emerged as electrical coupling was decreasing, during the second postnatal week. Our results demonstrate that thalamic relay neurons communicate primarily via electrical synapses during early postnatal development, and then lose their electrical coupling as a chemical synapse‐mediated inhibitory circuit matures.
Film-Cooling Effectiveness on a Rotating Turbine Platform Using Pressure Sensitive Paint Technique
Authors: Suryanarayanan A. , Ozturk B. , Schobeiri M. T. , Han J. C.
Published: May 2010

Film-cooling effectiveness is measured on a rotating turbine blade platform for coolant injection through discrete holes using pressure sensitive paint technique. Most of the existing literatures provide information only for stationary endwalls. The effects of rotation on the platform film-cooling effectiveness are not well documented. Hence, the existing three-stage turbine research facility at the Turbomachinery and Flow Performance Laboratory, Texas A&M University was redesigned and installed to enable coolant gas injection on the first stage rotor platform. Two distinct coolant supply loops were incorporated into the rotor to facilitate separate feeds for upstream cooling using stator-rotor gap purge flow and downstream discrete-hole film cooling. As a continuation of the previously published work involving stator-rotor gap purge cooling, this study investigates film-cooling effectiveness on the first stage rotor platform due to coolant gas injection through nine discrete holes located downstream within the passage region. Film-cooling effectiveness is measured for turbine rotor frequencies of 2400 rpm, 2550 rpm, and 3000 rpm corresponding to rotation numbers of Ro=0.18, 0.19, and 0.23, respectively. For each of the turbine rotational frequencies, film-cooling effectiveness is determined for average film-hole blowing ratios of Mholes=0.5, 0.75, 1.0, 1.25, 1.5, and 2.0. To provide a complete picture of hub cooling under rotating conditions, simultaneous injection of coolant gas through upstream stator-rotor purge gap and downstream discrete film-hole is also studied. The combined tests are conducted for gap purge flow corresponding to coolant to mainstream mass flow ratio of MFR=1% with three downstream film-hole blowing ratios of Mholes=0.75, 1.0, and 1.25 for each of the three turbine speeds. The results for combined upstream stator-rotor gap purge flow and downstream discrete holes provide information about the optimum purge flow coolant mass, average coolant hole blowing ratios for each rotational speed, and coolant injection location along the passage to obtain efficient platform film cooling.
Prediction of Evaporative Effects Within the Blading of an Industrial Axial Compressor
Authors: Matz Charles , Cataldi Giovanni , Kappis Wolfgang , Mundinger Gerd , Bischoff Stefan , Helland Eivind , Ripken Matthias
Published: May 2010

The results of a compressor flow-analysis code calibration study for estimating the effects of water evaporation within the blade rows of industrial axial compressors are presented. In this study, a mean-line code was chosen for the calibration tool due to its accepted use during preliminary design studies, at which time during the compressor design process one would logically consider power augmentation through wet compression. The calibrated code features a nonequilibrium thermodynamic single-droplet evaporation model augmented with an empirical splashing model, which, as input, uses measurements of droplet spectra data taken on water injection nozzles in an intake rig configured with realistic length scales. In addition, a wetted-airfoil-surface flow-angle deviation model is applied to predict changes in compressor stage characteristics, which, in turn, affect the inlet mass flow of the compressor. The test vehicle for calibration was a 50 Hz Alstom industrial gas turbine. Once calibrated, the code was successfully utilized to predict wet-compression effects for three additional like-family Alstom gas turbines operating at constant speed while under full load. The effects modeled by the code include bleed supply pressure suck-down and bleed temperature cool-down effects, as well as compressor inlet mass flow and power consumption effects.
Velocity Distributions for Low Pressure Turbines
Authors: Coull J. D. , Thomas R. L. , Hodson H. P.
Published: May 2010

A parametric set of velocity distributions has been investigated using a flat-plate experiment. Three different diffusion factors and peak velocity locations were tested. These were designed to mimic the suction surfaces of low pressure (LP) turbine blades. Unsteady wakes, inherent in real turbomachinery flows, were generated using a moving bar mechanism. A turbulence grid generated a freestream turbulence level that is believed to be typical of LP turbines. Measurements were taken across a Reynolds number range 50,000–220,000 at three reduced frequencies (0.314, 0.628, and 0.942). Boundary layer traverses were performed at the nominal trailing edge using a laser Doppler anemometry system and hot films were used to examine the boundary layer behavior along the surface. For every velocity distribution tested, the boundary layer separated in the diffusing flow downstream of the peak velocity. The loss production is dominated by the mixing in the reattachment process, mixing in the turbulent boundary layer downstream of reattachment, and the effects of the unsteady interaction between the wakes and the boundary layer. A sensitive balance governs the optimal location of peak velocity on the surface. Moving the velocity peak forward on the blade was found to be increasingly beneficial when bubble-generated losses are high, i.e. at low Reynolds number, at low reduced frequency, and at high diffusion factors.
Improved Understanding of Blow-Down in Filament Seals
Authors: Franceschini Gervas , Jones Terry V. , Gillespie David R. H.
Published: May 2010

Brush seals are used to provide flow resistance between rotating and stationary components in gas turbines. Compliant filament seals, such as brush seals, exhibit a phenomenon called blow-down, where the filaments deflect toward the rotor surface when a differential pressure is applied across the seal. This phenomenon is desirable as it enables seal contact to be maintained during rotor contractions and eccentric excursions. This paper describes an aerodynamic mechanism, which can cause the blow-down of bristles. Importantly it shows that distortion of the bristle pack is not necessary to achieve blow-down. Experimental and computational investigations of a large scale model representative of a section of a brush seal are also reported. The measured and predicted detailed pressure distributions thus obtained are used to validate the model of blow-down presented.
Multi-Objective Aerodynamic Optimization of Axial Turbine Blades Using a Novel Multilevel Genetic Algorithm
Authors: Öksüz Özhan , Akmandor İbrahim Sinan
Published: May 2010

In this paper, a new multiploid genetic optimization method handling surrogate models of the CFD solutions is presented and applied for a multi-objective turbine blade aerodynamic optimization problem. A fast, efficient, robust, and automated design method is developed to aerodynamically optimize 3D gas turbine blades. The design objectives are selected as maximizing the adiabatic efficiency and torque so as to reduce the weight, size, and cost of the gas turbine engine. A 3D steady Reynolds averaged Navier–Stokes solver is coupled with an automated unstructured grid generation tool. The solver is verified using two well-known test cases. The blade geometry is modeled by 36 design variables plus the number of blade variables in a row. Fine and coarse grid solutions are respected as high- and low-fidelity models, respectively. One of the test cases is selected as the baseline and is modified by the design process. It was found that the multiploid multi-objective genetic algorithm successfully accelerates the optimization and prevents the convergence with local optimums.
Robust and General Method for Determining Surface Fluid Flow Boundary
Conditions in Articular Cartilage Contact Mechanics Modeling
Authors: Pawaskar Sainath Shrikant , Fisher John , Jin Zhongmin
Published: May 2010

Contact detection in cartilage contact mechanics is an important feature of any analytical or computational modeling investigation when the biphasic nature of cartilage and the corresponding tribology are taken into account. The fluid flow boundary conditions will change based on whether the surface is in contact or not, which will affect the interstitial fluid pressurization. This in turn will increase or decrease the load sustained by the fluid phase, with a direct effect on friction, wear, and lubrication. In laboratory experiments or clinical hemiarthroplasty, when a rigid indenter or metallic prosthesis is used to apply load to the cartilage, there will not be any fluid flow normal to the surface in the contact region due to the impermeable nature of the indenter/prosthesis. In the natural joint, on the other hand, where two cartilage surfaces interact, flow will depend on the pressure difference across the interface. Furthermore, in both these cases, the fluid would flow freely in non-contacting regions. However, it should be pointed out that the contact area is generally unknown in advance in both cases and can only be determined as part of the solution. In the present finite element study, a general and robust algorithm was proposed to decide nodes in contact on the cartilage surface and, accordingly, impose the fluid flow boundary conditions. The algorithm was first tested for a rigid indenter against cartilage model. The algorithm worked well for two-dimensional four-noded and eight-noded axisymmetric element models as well as three-dimensional models. It was then extended to include two cartilages in contact. The results were in excellent agreement with the previous studies reported in the literature.
Visualizing Flow Partitioning in a Model of the Upper Human Lung Airways
Authors: Bauer K. , Chaves H. , Brücker Ch.
Published: May 2010

The convective transport of fluid within the human upper airways is investigated in a transparent model of the tracheobronchial tree. Oscillatory flow through the branching network with six generations was studied at varying Reynolds numbers between 400 and 2600 and Womersley numbers from 5.5 to 12.3 in the trachea representing clinical conditions during high frequency oscillatory ventilation. The flow partitioning within the model was visualized using advection of neutrally buoyant tracer particles, which were illuminated by short light pulses and recorded by a high speed camera. Integration of the particle locations for a large number of cycles provides the probability distribution of particles passing certain branches within the bifurcating network, and thus, the dispersion of particles in the airways. The results show the different characteristics of flow partitioning at varying Womersley and Reynolds numbers.
Deformable Mock Stenotic Artery With a Lipid Pool
Authors: Pazos V. , Mongrain R. , Tardif J. C.
Published: May 2010

The comparison, evaluation, and optimization of new techniques, models, or algorithms often require the use of realistic deformable test phantoms. The purpose of this paper is to present a multilayer deformable test specimen mimicking an atherosclerotic coronary artery, suitable for mechanical testing and intravascular imaging. Mock arteries were constructed in three phases using two molds: building a first layer of polyvinyl alcohol (PVA) cryogel, adding a lipid pool and building a second layer of PVA cryogel. To illustrate the deformation of the mock arteries, one has been placed in a custom-made bath, axially stretched then inflated while acquiring intravascular ultrasound (IVUS) images. The resulting specimen presents a progressing lumen narrowing of 25% in cross-sectional area at the peak and a lipid pool. The average inner gel layer is about 0.4 mm thick and the outer about 0.6 mm. The dimensions are of the same order as clinical observations, the first gel layer mimicking the intima-media and the second layer the adventitia. In the sequence of IVUS images, the different components of the mock artery are visible and differentiable. The variation in diameter of the segmented contours is presented for a specific specimen subjected to intraluminal pressure. This double-layer stenotic mock artery is approximately the size of a human coronary artery, has a lipid inclusion, can withstand relative large deformation, suitable for (intravascular) ultrasound imaging, and has customizable geometry and wall material parameters.
Optimization of Inflow Waveform Phase-Difference for Minimized Total Cavopulmonary Power Loss
Authors: Dur Onur , DeGroff Curt G. , Keller Bradley B. , Pekkan Kerem
Published: May 2010

The Fontan operation is a palliative surgical procedure performed on children, born with congenital heart defects that have yielded only a single functioning ventricle. The total cavo-pulmonary connection (TCPC) is a common variant of the Fontan procedure, where the superior vena cava (SVC) and inferior vena cava (IVC) are routed directly into the pulmonary arteries (PA). Due to the limited pumping energy available, optimized hemodynamics, in turn, minimized power loss, inside the TCPC pathway is required for the best optimal surgical outcomes. To complement ongoing efforts to optimize the anatomical geometric design of the surgical Fontan templates, here, we focused on the characterization of power loss changes due to the temporal variations in between SVC and IVC flow waveforms. An experimentally validated pulsatile computational fluid dynamics solver is used to quantify the effect of phase-shift between SVC and IVC inflow waveforms and amplitudes on internal energy dissipation. The unsteady hemodynamics of two standard idealized TCPC geometries are presented, incorporating patient-specific real-time PC-MRI flow waveforms of “functional” Fontan patients. The effects of respiration and pulsatility on the internal energy dissipation of the TCPC pathway are analyzed. Optimization of phase-shift between caval flows is shown to lead to lower energy dissipation up to 30% in these idealized models. For physiological patient-specific caval waveforms, the power loss is reduced significantly (up to 11%) by the optimization of all three major harmonics at the same mean pathway flow (3 L/min). Thus, the hemodynamic efficiency of single ventricle circuits is influenced strongly by the caval flow waveform quality, which is regulated through respiratory dependent physiological pathways. The proposed patient-specific waveform optimization protocol may potentially inspire new therapeutic applications to aid postoperative hemodynamics and improve the well being of the Fontan patients.
Mixed Experimental and Numerical Approach for Characterizing the Biomechanical Response of the Human Leg Under Elastic Compression
Authors: Avril Stéphane , Bouten Laura , Dubuis Laura , Drapier Sylvain , Pouget Jean-François
Published: May 2010

Elastic compression is the process of applying an elastic garment around the leg, supposedly for enhancing the venous flow. However, the response of internal tissues to the external pressure is still partially unknown. In order to improve the scientific knowledge about this topic, a slice of a human leg wearing an elastic garment is modeled by the finite-element method. The elastic properties of the tissues inside the leg are identified thanks to a dedicated approach based on image processing. After calibrating the model with magnetic resonance imaging scans of a volunteer, the pressure transmitted through the internal tissues of the leg is computed. Discrepancies of more than 35% are found from one location to another, showing that the same compression garment cannot be applied for treating deficiencies of the deep venous system or deficiencies of the large superficial veins. Moreover, it is shown that the internal morphology of the human leg plays an important role. Accordingly, the approach presented in this paper may provide useful information for adapting compression garments to the specificity of each patient.
A Novel Stent for Percutaneous Heart Valve Implantation: First In Vitro Results
Authors: Marchand C. , Heim F. , Durand B.
Published: May 2010

Percutaneous aortic valve implantation has become an alternative technique to surgical valve replacement in patients with high risk for surgery. This technique is at its beginning and stents used for valve prostheses remain standard vascular stents. These stents are, however, not designed to undergo heart valve stress. They do not match the aortic environment geometry, and induce exaggerated tissue traumatism. Reduced implant lifetime may therefore be expected. The purpose of the present work is to evaluate in vitro the technical feasibility of noninvasive aortic valve replacement with a novel more specific stent. This stent is especially adapted to its implantation environment with a design that matches the shape of the aortic root while respecting the valve functions. We present a design, a manufacturing process and in vitro performances for the stent under static pressure loading and pulsatile flow. The stent shows good dynamic behavior in keeping position imposed at implantation time and in matching the aortic root dimensions changes. Prosthesis static and dynamic regurgitation are evaluated and show values close to those obtained with other commercially available prostheses.