bluuebunny/crossref_metadata_2025 huggingface dataset:
A Discontinuous Galerkin Global Shallow Water Model
Authors: Nair Ramachandran D. , Thomas Stephen J. , Loft Richard D.
Published: April 2005

A discontinuous Galerkin shallow water model on the cubed sphere is developed, thereby extending the transport scheme developed by Nair et al. The continuous flux form nonlinear shallow water equations in curvilinear coordinates are employed. The spatial discretization employs a modal basis set consisting of Legendre polynomials. Fluxes along the element boundaries (internal interfaces) are approximated by a Lax–Friedrichs scheme. A third-order total variation diminishing Runge–Kutta scheme is applied for time integration, without any filter or limiter. Numerical results are reported for the standard shallow water test suite. The numerical solutions are very accurate, there are no spurious oscillations in test case 5, and the model conserves mass to machine precision. Although the scheme does not formally conserve global invariants such as total energy and potential enstrophy, conservation of these quantities is better preserved than in existing finite-volume models.
Chronic Refractory ITP in Children: Beyond Splenectomy
Authors: Sevier Nicole , Houston Mary
Published: April 2005

Idiopathic (or immune) thrombocytopenic purpura (ITP) is a relatively common hematologic condition, but one that the hematology community has failed to reach a consensus on with regard to treatment. In patients with chronic refractory ITP, there is even less agreement about treatment approaches, as this population represents a small, but challenging, fraction of the total cases of ITP. The aim of this article is to review the treatment options available for children with chronic refractory ITP, including a review of the benefits versus risks, rate of remission, and areas of ongoing and future research.
A Review and Synthesis of Research Evidence for Self-Efficacy-Enhancing Interventions for Reducing Chronic Disability: Implications for Health Education Practice (Part II)
Authors: Marks Ray , Allegrante John P.
Published: April 2005

Chronic diseases such as arthritis, diabetes, and heart disease that cause pain, functional impairment, social and emotional dysfunction, and premature loss of wage earnings constitute a challenging problem for American society. In the absence of any effective cure for these frequently progressive conditions, the secondary prevention of complications, which requires a high degree of communication and cooperation between patient and clinician, and improving quality of life and functional capacity through better disease self-management becomes critical and are key objectives of Healthy People 2010. Part I of this two-part article described the common clinical features of chronic disease, the diverse disease management strategies used for alleviating pain and preventing disability, and the role of self-efficacy as a framework for intervention. This companion article identifies and synthesizes the key research evidence for educational interventions designed to enhance individual self-efficacy perceptions and presents implications for improving practices in patient education for chronic diseases.
Association of current smoking with airway inflammation in chronic obstructive pulmonary disease and asymptomatic smokers
Authors: Willemse Brigitte WM , ten Hacken Nick HT , Rutgers Bea , Postma Dirkje S , Timens Wim
Published: April 2005

Background

Inflammation in the airways and lung parenchyma underlies fixed airway obstruction in chronic obstructive pulmonary disease. The exact role of smoking as promoting factor of inflammation in chronic obstructive pulmonary disease is not clear, partly because studies often do not distinguish between current and ex-smokers.

Methods

We investigated airway inflammation in sputum and bronchial biopsies of 34 smokers with chronic obstructive pulmonary disease (9 Global initiative for Chronic Obstructive Lung Disease stage 0, 9 stage I, 10 stage II and 6 stage III) and 26 asymptomatic smokers, and its relationship with past and present smoking habits and airway obstruction.

Results

Neutrophil percentage, interleukin-8 and eosinophilic-cationic-protein levels in sputum were higher in chronic obstructive pulmonary disease (stage I-III) than asymptomatic smokers. Inflammatory cell numbers in bronchial biopsies were similar in both groups. Current smoking correlated positively with macrophages: in bronchial biopsies in both groups, and in sputum in chronic obstructive pulmonary disease. Pack-years smoking correlated positively with biopsy macrophages only in chronic obstructive pulmonary disease.

Conclusion

Inflammatory effects of current smoking may mask the underlying ongoing inflammatory process pertinent to chronic obstructive pulmonary disease. This may have implications for future studies, which should avoid including mixed populations of smokers and ex-smokers.
Detailed protein sequence alignment based on Spectral Similarity Score (SSS)
Authors: Gupta Kshitiz , Thomas Dina , Vidya SV , Venkatesh KV , Ramakumar S
Published: April 2005

Background

The chemical property and biological function of a protein is a direct consequence of its primary structure. Several algorithms have been developed which determine alignment and similarity of primary protein sequences. However, character based similarity cannot provide insight into the structural aspects of a protein. We present a method based on spectral similarity to compare subsequences of amino acids that behave similarly but are not aligned well by considering amino acids as mere characters. This approach finds a similarity score between sequences based on any given attribute, like hydrophobicity of amino acids, on the basis of spectral information after partial conversion to the frequency domain.

Results

Distance matrices of various branches of the human kinome, that is the full complement of human kinases, were developed that matched the phylogenetic tree of the human kinome establishing the efficacy of the global alignment of the algorithm. PKCd and PKCe kinases share close biological properties and structural similarities but do not give high scores with character based alignments. Detailed comparison established close similarities between subsequences that do not have any significant character identity. We compared their known 3D structures to establish that the algorithm is able to pick subsequences that are not considered similar by character based matching algorithms but share structural similarities. Similarly many subsequences with low character identity were picked between xyna-theau and xyna-clotm F/10 xylanases. Comparison of 3D structures of the subsequences confirmed the claim of similarity in structure.

Conclusion

An algorithm is developed which is inspired by successful application of spectral similarity applied to music sequences. The method captures subsequences that do not align by traditional character based alignment tools but give rise to similar secondary and tertiary structures. The Spectral Similarity Score (SSS) is an extension to the conventional similarity methods and results indicate that it holds a strong potential for analysis of various biological sequences and structural variations in proteins.
Identification of a novel Rev-interacting cellular protein
Authors: Kramer-Hämmerle Susanne , Ceccherini-Silberstein Francesca , Bickel Christian , Wolff Horst , Vincendeau Michelle , Werner Thomas , Erfle Volker , Brack-Werner Ruth
Published: April 2005

Background

Human cell types respond differently to infection by human immunodeficiency virus (HIV). Defining specific interactions between host cells and viral proteins is essential in understanding how viruses exploit cellular functions and the innate strategies underlying cellular control of HIV replication. The HIV Rev protein is a post-transcriptional inducer of HIV gene expression and an important target for interaction with cellular proteins. Identification of Rev-modulating cellular factors may eventually contribute to the design of novel antiviral therapies.

Results

Yeast-two hybrid screening of a T-cell cDNA library with Rev as bait led to isolation of a novel human cDNA product (16.4.1). 16.4.1-containing fusion proteins showed predominant cytoplasmic localization, which was dependent on CRM1-mediated export from the nucleus. Nuclear export activity of 16.4.1 was mapped to a 60 amino acid region and a novel transport signal identified. Interaction of 16.4.1 with Rev in human cells was shown in a mammalian two-hybrid assay and by colocalization of Rev and 16.4.1 in nucleoli, indicating that Rev can recruit 16.4.1 to the nucleus/nucleoli. Rev-dependent reporter expression was inhibited by overexpressing 16.4.1 and stimulated by siRNAs targeted to 16.4.1 sequences, demonstrating that 16.4.1 expression influences the transactivation function of Rev.

Conclusion

These results suggest that 16.4.1 may act as a modulator of Rev activity. The experimental strategies outlined in this study are applicable to the identification and biological characterization of further novel Rev-interacting cellular factors.
Characterisation of the genomic architecture of human chromosome 17q and evaluation of different methods for haplotype block definition
Authors: Zeggini Eleftheria , Barton Anne , Eyre Stephen , Ward Daniel , Ollier William , Worthington Jane , John Sally
Published: April 2005

Background

The selection of markers in association studies can be informed through the use of haplotype blocks. Recent reports have determined the genomic architecture of chromosomal segments through different haplotype block definitions based on linkage disequilibrium (LD) measures or haplotype diversity criteria. The relative applicability of distinct block definitions to association studies, however, remains unclear. We compared different block definitions in 6.1 Mb of chromosome 17q in 189 unrelated healthy individuals. Using 137 single nucleotide polymorphisms (SNPs), at a median spacing of 15.5 kb, we constructed haplotype block maps using published methods and additional methods we have developed. Haplotype tagging SNPs (htSNPs) were identified for each map.

Results

Blocks were found to be shorter and coverage of the region limited with methods based on LD measures, compared to the method based on haplotype diversity. Although the distribution of blocks was highly variable, the number of SNPs that needed to be typed in order to capture the maximum number of haplotypes was consistent.

Conclusion

For the marker spacing used in this study, choice of block definition is not important when used as an initial screen of the region to identify htSNPs. However, choice of block definition has consequences for the downstream interpretation of association study results.
Investigating hookworm genomes by comparative analysis of two Ancylostoma species
Authors: Mitreva Makedonka , McCarter James P , Arasu Prema , Hawdon John , Martin John , Dante Mike , Wylie Todd , Xu Jian , Stajich Jason E , Kapulkin Wadim , Clifton Sandra W , Waterston Robert H , Wilson Richard K
Published: April 2005

Background

Hookworms, infecting over one billion people, are the mostly closely related major human parasites to the model nematode Caenorhabditis elegans. Applying genomics techniques to these species, we analyzed 3,840 and 3,149 genes from Ancylostoma caninum and A. ceylanicum.

Results

Transcripts originated from libraries representing infective L3 larva, stimulated L3, arrested L3, and adults. Most genes are represented in single stages including abundant transcripts like hsp-20 in infective L3 and vit-3 in adults. Over 80% of the genes have homologs in C. elegans, and nearly 30% of these were with observable RNA interference phenotypes. Homologies were identified to nematode-specific and clade V specific gene families. To study the evolution of hookworm genes, 574 A. caninum / A. ceylanicum orthologs were identified, all of which were found to be under purifying selection with distribution ratios of nonsynonymous to synonymous amino acid substitutions similar to that reported for C. elegans / C. briggsae orthologs. The phylogenetic distance between A. caninum and A. ceylanicum is almost identical to that for C. elegans / C. briggsae.

Conclusion

The genes discovered should substantially accelerate research toward better understanding of the parasites' basic biology as well as new therapies including vaccines and novel anthelmintics.
Relative transcript quantification by Quantitative PCR: Roughly right or precisely wrong?
Authors: Skern Rasmus , Frost Petter , Nilsen Frank
Published: April 2005

Background

When estimating relative transcript abundances by quantitative real-time PCR (Q-PCR) we found that the results can vary dramatically depending on the method chosen for data analysis.

Results

Analyses of Q-PCR results from a salmon louse starvation experiment show that, even with apparently good raw data, different analytical approaches [1, 2] may lead to opposing biological conclusions.

Conclusion

The results emphasise the importance of being cautious when analysing Q-PCR data and indicate that uncritical routine application of an analytical method will eventually result in incorrect conclusions. We do not know the extent of, or have a universal solution to this problem. However, we strongly recommend caution when analysing Q-PCR results e.g. by using two or more analytical approaches to validate conclusions. In our view a common effort should be made to standardise methods for analysis and validation of Q-PCR results.
The strengths and limitations of meta-analyses based on aggregate data
Authors: Lyman Gary H , Kuderer Nicole M
Published: April 2005

Background

Properly performed systematic reviews and meta-analyses are thought by many to represent among the highest level of evidence addressing important clinical issues. Few would disagree that meta-analyses based on individual patient data (IPD) offer several advantages and represent the standard to which all other systematic reviews should be compared.

Methods

All cancer-related meta-analyses cited in Medline were classified as based on aggregate or individual patient data. A review was then undertaken of all reports comparing the comparative strengths and limitations of meta-analyses using either aggregate or individual patient data.

Results

The majority of published meta-analyses are based on summary or aggregate patient data (APD). Reasons suggested for this include the considerable resources, years of study and often, broad international cooperation required for IPD meta-analyses. Many of the most important features of systematic reviews including formal meta-analyses are addressed by both IPD and APD meta-analyses. The need for defining an explicit and relevant clinical question, exhaustively searching for the totality of evidence, meticulous and unbiased data transfer or extraction, assessment of between study heterogeneity and the use of appropriate statistical methods for estimating summary effect measures are essentially the same for the two approaches.

Conclusion

IPD offers advantages and, when feasible, should be considered the best opportunity to summarize the results of multiple studies. However, the resources, time and cooperation required for such studies will continue to limit their use in many important areas of clinical medicine which can be meaningfully and cost-effectively approached by properly performed APD meta-analyses. APD meta-analyses continue to be the mainstay of systematic reviews utilized by the US Preventive Services Task Force, the Cochrane Collaboration and many professional societies to support clinical practice guidelines.
The prognostic value of the hypoxia markers CA IX and GLUT 1 and the cytokines VEGF and IL 6 in head and neck squamous cell carcinoma treated by radiotherapy ± chemotherapy
Authors: De Schutter Harlinde , Landuyt Willy , Verbeken Erik , Goethals Laurence , Hermans Robert , Nuyts Sandra
Published: April 2005

Background

Several parameters of the tumor microenvironment, such as hypoxia, inflammation and angiogenesis, play a critical role in tumor aggressiveness and treatment response. A major question remains if these markers can be used to stratify patients to certain treatment protocols.

The purpose of this study was to investigate the inter-relationship and the prognostic significance of several biological and clinicopathological parameters in patients with head and neck squamous cell carcinoma (HNSCC) treated by radiotherapy ± chemotherapy.

Methods

We used two subgroups of a retrospective series for which CT-determined tumoral perfusion correlated with local control. In the first subgroup (n = 67), immunohistochemistry for carbonic anhydrase IX (CA IX) and glucose transporter-1 (GLUT-1) was performed on the pretreatment tumor biopsy. In the second subgroup (n = 34), enzyme linked immunosorbent assay (ELISA) was used to determine pretreatment levels of the cytokines vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in serum. Correlation was investigated between tumoral perfusion and each of these biological markers, as well as between the markers mutually. The prognostic value of these microenvironmental parameters was also evaluated.

Results

For CA IX and GLUT-1, the combined assessment of patients with both markers expressed above the median showed an independent correlation with local control (p = 0.02) and disease-free survival (p = 0.04) with a trend for regional control (p = 0.06).

In the second subgroup, IL-6 pretreatment serum level above the median was the only independent predictor of local control (p = 0.009), disease-free survival (p = 0.02) and overall survival (p = 0.005).

Conclusion

To our knowledge, we are the first to report a link in HNSCC between IL-6 pretreatment serum levels and radioresistance in vivo. This link is supported by the strong prognostic association of pretreatment IL-6 with local control, known to be the most important parameter to judge radiotherapy responses.

Furthermore, the combined assessment of CA IX and GLUT-1 correlated independently with prognosis. This is a valuable indication that a combined approach is important in the investigation of prognostic markers.
Posttraumatic stress disorder: An exploratory study examining rates of trauma and PTSD and its effect on client outcomes in community mental health
Authors: Howgego Irene M , Owen Cathy , Meldrum Lenore , Yellowlees Peter , Dark Frances , Parslow Ruth
Published: April 2005

Background

Rates of trauma and Posttraumatic Stress Disorder (PTSD) were examined in order to compare the profile in clients of an Australian Public Mental Health Service with that reported in the international literature for clients with major mental illness and to explore the effect of this on client health outcomes. Potential factors contributing to increased levels of trauma/PTSD in this group of clients and the issue of causality between PTSD and subsequent mental illness was also explored.

Methods

A convenience sample of 29 clients was screened for trauma and PTSD using the Posttraumatic Stress Diagnostic Scale™ (PDS) and selected outcome measures. Paired and independent samples t-test and ANOVA were applied to the data.

Results

High levels of undocumented trauma and PTSD were found. Twenty clients, (74%) reported exposure to multiple traumatic events; 33.3% (9) met DSM IV diagnostic criteria for PTSD. Significant difference was found for PTSD symptomatology, severity and impairment and for client and clinician-rated scores of Quality of Life (QOL) outcomes in the PTSD group. No effect for PTSD symptomatology on the Working Alliance (WA) was found. Factors that may influence higher rates of PTSD in this group were identified and included issues associated with the population studied, the predominance of assaultive violence found, and vulnerability and risks factors associated with re-traumatisation within the social and treating environments.

Conclusion

A similar trauma and PTSD profile to that reported in the international literature, including greater levels of trauma and PTSD and a poorer QOL, was found in this small sample of clients. It is postulated that the increased levels of trauma/PTSD as reported for persons with major mental illness, including those found in the current study, are primarily related to the characteristics of the population that access public mainstream psychiatric services and that these factors have specific implications for service delivery, and raise issues of efficiency and effectiveness of resource use in achieving successful outcomes in public mental health services for clients with co-morbid PTSD. Further research with a more rigorous design is needed to test these preliminary findings within Australian Community Mental Health Services.
Introducing the National Library for Health Skin Conditions Specialist Library
Authors: Grindlay Douglas , Boulos Maged N Kamel , Williams Hywel C
Published: April 2005

Background

This paper introduces the new National Library for Health Skin Conditions Specialist Library http://www.library.nhs.uk/skin.

Description

The aims, scope and audience of the new NLH Skin Conditions Specialist Library, and the composition and functions of its core Project Team, Editorial Team and Stakeholders Group are described. The Library's collection building strategy, resource and information types, editorial policies, quality checklist, taxonomy for content indexing, organisation and navigation, and user interface are all presented in detail. The paper also explores the expected impact and utility of the new Library, as well as some possible future directions for further development.

Conclusion

The Skin Conditions Specialist Library is not just another new Web site that dermatologists might want to add to their Internet favourites then forget about it. It is intended to be a practical, "one-stop shop" dermatology information service for everyday practical use, offering high quality, up-to-date resources, and adopting robust evidence-based and knowledge management approaches.
Human T-cell leukemia virus type I (HTLV-I) infection and the onset of adult T-cell leukemia (ATL)
Authors: Matsuoka Masao
Published: April 2005

The clinical entity of adult T-cell leukemia (ATL) was established around 1977, and human T-cell leukemia virus type 1 (HTLV-I) was subsequently identified in 1980. In the 25 years since the discovery of HTLV-I, HTLV-I infection and its associated diseases have been extensively studied, and many of their aspects have been clarified. However, the detailed mechanism of leukemogenesis remains unsolved yet, and the prognosis of ATL patients still poor because of its resistance to chemotherapy and immunodeficiency. In this review, I highlight the recent progress and remaining enigmas in HTLV-I infection and its associated diseases, especially ATL.
Pharmacokinetics of 5-Azacitidine Administered With Phenylbutyrate in Patients With Refractory Solid Tumors or Hematologic Malignancies
Authors: Rudek Michelle A. , Zhao Ming , He Ping , Hartke Carol , Gilbert Jill , Gore Steven D. , Carducci Michael A. , Baker Sharyn D.
Published: April 2005

Purpose

To characterize the pharmacokinetic behavior of 5-azacitidine (5-AC), a cytidine nucleoside analog, when given with phenylbutyrate, a histone deaceytlase inhibitor.

Patients and Methods

Pharmacokinetic data were obtained from two trials involving patients with solid tumor and hematologic malignancies. 5-AC at doses ranging from 10 to 75 mg/m2/d was administered once daily as a subcutaneous injection for 5 to 21 days in combination with phenylbutyrate administered as a continuous intravenous infusion for varying dose and duration every 28 or 35 days. Serial plasma samples were collected up to 24 hours after 5-AC administration. 5-AC was quantitated using a validated liquid chromatograph/tandem mass spectrometry method.

Results

5-AC was rapidly absorbed with the mean Tmax occurring at 0.47 hour. Average maximum concentration (Cmax) and area under the curve (AUC0-∞) values increased in a dose-proportionate manner with increasing dose from 10 to 75 mg/m2/d; the mean ± SD Cmax and AUC0-∞ at 10 mg/m2/d were 776 ± 459 nM and 1,355 ± 1,125 h*nM, respectively, and at 75 mg/m2/d were 4,871 ± 1,398 nM and 6,582 ± 2,560 h*nM, respectively. Despite a short terminal half-life of 1.5 ± 2.3 hours, inhibition of DNA methyl transferase activity in tumors of patients receiving 5-AC has been documented.

Conclusion

5-AC is rapidly absorbed and eliminated when administered subcutaneously. Sufficient 5-AC exposure is achieved to produce pharmacodynamic effects in tumors.
The Microsurgical Nuances of Resecting Tuberculum Sellae Meningiomas
Authors: Benjamin Vallo , Russell Stephen M.
Published: April 2005

In a recent article, our experience and knowledge of the clinical picture, microsurgical anatomy, and long-term surgical outcome of resecting tuberculum sellae meningiomas was described in detail. We now present our surgical technique in a pictorial and video format for the benefit of neurosurgeons in training, as well as for general critique. Attention is given to the details of surgery: patient positioning, surgical approaches, technique of tumor removal, and postoperative care.
Anatomic Landmarks for Nerves of the Neck: A Vade Mecum for Neurosurgeons
Authors: Tubbs R. Shane , Salter E. George , Oakes W. Jerry
Published: April 2005

ANATOMIC LANDMARKS ARE often quite useful in localizing structures within the human body, especially in the surgical realm. We have reviewed the medical literature and multiple texts of surgery and anatomy and culled together many anatomic landmarks regarding important nerves of the neck. This region is complicated by formidable anatomy, and a single collection of the relationships of the nerves in this region is lacking in the literature. It is our hope that this collection will serve to assist the surgeon who operates in this region of the body.
Quantitative Anatomic Study of Three Surgical Approaches to the Anterior Communicating Artery Complex
Authors: Figueiredo Eberval Gadelha , Deshmukh Pushpa , Zabramski Joseph M. , Preul Mark C. , Crawford Neil R. , Siwanuwatn Rungsak , Spetzler Robert F.
Published: April 2005

OBJECTIVE:

To compare the angles of approach and area of exposure to the anterior communicating artery (AComA) complex associated with pterional (PT), orbitopterional (OPT), and orbitozygomatic (OZ) craniotomies before and after gyrus rectus resection.

METHODS:

PT, OPT, and OZ craniotomies were performed on both sides of four heads, and the angles of approach and area of exposure to the AComA complex were measured before and after resection of the gyrus rectus.

RESULTS:

The vertical angle of approach increased significantly among the PT and OPT (P = 0.001), PT and OZ (P = 0.001), and OPT and OZ approaches (P = 0.005). The horizontal angle of approach was significantly larger between the PT to OPT (P = 0.001) and PT to OZ (P = 0.001) approaches but not between the OPT and OZ approaches (P = 0.757). After gyrus rectus resection, the vertical and horizontal angles of approach increased significantly for the PT approach but not for the OPT and OZ approaches. The area of exposure to the AComA complex increased progressively from the PT to OPT to OZ approach but did not reach statistical significance (P = 0.124). Resection of the gyrus rectus resulted in significant relative gains in the area of exposure for the PT (P = 0.01) and OPT (P = 0.04) approaches but not for the OZ approach (P = 0.88).

CONCLUSION:

The vertical and horizontal angles of approach to the AComA complex are significantly larger for the OPT and OZ approaches compared with the PT approach. Use of the OZ approach may decrease the need for frontal lobe retraction and resection of the gyrus rectus.
Lateral Transsulcal Approach to Asymptomatic Trigonal Meningiomas with Correlative Microsurgical Anatomy: Technical Case Report
Authors: Nagata Shinji , Sasaki Tomio
Published: April 2005

OBJECTIVE:

We introduce the lateral transsulcal approach to asymptomatic trigonal meningiomas.

METHODS:

The approach was studied in two cadaver brains and three asymptomatic patients with trigonal meningiomas. The posterior part of the sylvian fissure, or superior temporal sulcus, is opened to the bottom. Through a small horizontal cortical incision, the trigone of the lateral ventricle is exposed in the shortest distance. The trigonal meningiomas are detached from the choroid plexus and removed.

RESULTS:

In patients with meningiomas on the nondominant side, the transsylvian approach was adopted. In patients with meningiomas on the dominant side, the transsylvian approach was adopted for patients with a wide sylvian cistern, and the approach through the superior temporal sulcus was adopted for patients with a narrow sylvian cistern. The transverse gyrus of Heschl was a good anatomic landmark in the operative field of the transsylvian approach. Patients with meningiomas on the dominant side exhibited transient amnestic aphasia and dyscalculia, but the symptoms disappeared in a few days or weeks. These patients were discharged without any neurological deficits. Although there are potential risks of damaging association fibers, optic radiation, the transverse gyrus of Heschl, and the parietal lobe, a thorough understanding of the topographical anatomy and careful dissection techniques can avoid morbidity. Wide opening of the sylvian fissure and debulking of the tumor are other important factors to reduce the retraction of the parietal and temporal lobes.

CONCLUSION:

The lateral transsulcal approach is applicable for small asymptomatic trigonal meningiomas with an acceptable risk of morbidity, even in the dominant hemisphere.
Intraoperative Motor Mapping of the Cerebral Peduncle during Resection of a Midbrain Cavernous Malformation: Technical Case Report
Authors: Quiñones-Hinojosa Alfredo , Lyon Russ , Du Rose , Lawton Michael T.
Published: April 2005

OBJECTIVE AND IMPORTANCE:

Brainstem cavernous malformations that seem to come to a pial or ependymal surface on preoperative magnetic resonance imaging studies may, in fact, be covered by an intact layer of neural tissue. For cavernous malformations in the cerebral peduncle, intraoperative stimulation mapping with a miniaturized probe can determine whether this overlying tissue harbors fibers in the corticospinal tract. In addition, intermittent monitoring with transcranial motor evoked potentials (TcMEPs) helps to protect this vital pathway during resection of the lesion.

CLINICAL PRESENTATION:

A 20-year-old woman collapsed after a cavernous malformation in the left cerebral peduncle hemorrhaged into the pons, midbrain, and thalamus. She presented with right hemiparesis and left oculomotor palsy.

INTERVENTION:

The cavernous malformation was completely resected through a left orbitozygomatic craniotomy and transsylvian approach. Stimulation mapping of the cerebral peduncle with a Kartush probe (Medtronic Xomed, Inc., Jacksonville, FL) identified the corticospinal tract lateral to the lesion, and a layer of tissue over the lesion harbored no motor fibers. TcMEP monitoring helped to guide the resection, with increased voltage thresholds and altered waveform morphologies indicating transient impaired motor conduction. All TcMEP changes returned to baseline by the end of the procedure, and the patient's hemiparesis improved after surgery.

CONCLUSION:

Stimulation mapping of the corticospinal tract and intermittent TcMEPs is a safe and simple surgical adjunct. Expanded monitoring of the motor pathway during the resection of cerebral peduncle cavernous malformations may improve the safety of these operations.
Surgical Clipping of Complex Basilar Apex Aneurysms: A Strategy for Successful Outcome Using the Pretemporal Transzygomatic Transcavernous Approach
Authors: Krisht Ali F. , Kadri Paulo A.S.
Published: April 2005

OBJECTIVE:

Complex basilar apex aneurysms (large size, wide and complex neck, tortuous parent vessels) continue to pose a challenge in treatment. Endovascular treatment has a high risk of recanalization, and surgical treatment is limited by the space and time necessary to achieve safe clipping. To overcome these obstacles, a modification of previously reported approaches was developed. The pretemporal transzygomatic transcavernous approach and a clipping strategy were used in the treatment of 21 high-complexity basilar apex aneurysms.

METHODS:

By use of the pretemporal route, the zygomatic notch was widened, the anterior clinoid was removed, the cavernous sinus was partially exposed, and the oculomotor nerve was mobilized. The depth of the field was widened by further cavernous exposure and the removal of the posterior clinoid. Temporary clips were applied to the basilar trunk perforator-free zone to preserve visualization of the aneurysm neck and perforators and to maintain collateral flow to the brainstem.

RESULTS:

Twenty-one high-complexity basilar apex aneurysms, 11 of which caused subarachnoid hemorrhage, were treated. Twenty (95%) were successfully clipped (Glasgow Outcome Scale scores, 4 or 5 in 90.5% at discharge; Rankin Disability Score, 1 in 90.5% at 1-yr follow-up). Complications were transient oculomotor palsy in all patients, small thalamic infarct in one patient, and cerebrospinal fluid leak in another. There was no surgical mortality. Delayed follow-up angiography in 19 of the 21 patients showed no residual aneurysm.

CONCLUSION:

We report the largest series of a unique, challenging group of complex basilar apex aneurysms treated with the pretemporal transzygomatic transcavernous approach, which provided improved safety of clipping by 1) increased visualization of the basilar apex and perforator arteries, 2) improved maneuverability of clip application, 3) a safer perforator-free location, and 4) preservation of brainstem collateral flow.
The Triangle of the Vertebral Artery
Authors: Tubbs R. Shane , Salter E. George , Wellons John C. , Blount Jeffrey P. , Oakes W. Jerry
Published: April 2005

OBJECTIVE:

Neurosurgical procedures such as proximal brachial plexus repair, scalenotomy, and direct isolation of the proximal vertebral artery require a good working knowledge of the triangle of the vertebral artery. This deep triangle of the neck is bound by the subclavian artery and the anterior scalene and longus cervicis muscles. In addition to the vertebral artery, many important structures are found in this area, such as the ganglionated sympathetic chain and certain cervical spinal nerves.

METHODS:

Twenty formalin-fixed cadavers were used for this study. Dissection of this triangle was performed, and measurements were made not only of parts of its borders, but also distances from these borders to neurologically important structures within its confines, such as the C8 spinal nerve.

RESULTS:

In all specimens, the middle scalene muscle was noted to form part of the posterior wall of the triangle. The mean height of the triangle was found to be 3.2 cm, and the mean width of its base was 1.3 cm. We observed that the C8 spinal nerve had a mean distance of 1.2 cm inferior to the apex of the triangle and that the C7 spinal nerve was found inside the triangle in 5% of sides. If the phrenic nerve entered the triangle, it was never found more than 6 mm medial to the anterior scalene muscle. The vertebral artery always traveled intimately along the lateral border of the longus cervicis muscle, and its lateral edge ranged 5 to 8 mm medial to the medial edge of the anterior scalene muscle.

CONCLUSION:

The C7 spinal nerve was observed in the triangle of the vertebral artery. In addition, the posterior border of the triangle of the vertebral artery was clearly defined in this study, and the middle scalene muscle could be used as a landmark. These data, coupled with our quantitation of parts and structures within the triangle, may assist neurosurgeons who operate on this area of the neck.
Endonasal Transsphenoidal Transclival Removal of Prepontine Epidermoid Tumors: Technical Note
Authors: Esposito Felice , Becker Donald P. , Villablanca Juan Pablo , Kelly Daniel F.
Published: April 2005

OBJECTIVE:

Prepontine retroclival tumors have typically been removed through a variety of anterolateral, lateral, and posterolateral cranial base approaches. Here, we describe an endonasal transclival cranial base approach for removal of prepontine epidermoid tumors.

METHODS:

Two men, 40 and 52 years old, each presented with a history of headaches and cranial nerve deficits. In each patient, magnetic resonance imaging showed a large T1 hypointense/T2 hyperintense mass occupying the posterior suprasellar, premesencephalic, and prepontine cisterns, with significant mass effect on the brainstem. Both patients underwent an endonasal transsphenoidal transclival cranial base tumor removal with the operating microscope and endoscopic assistance. The dural and bony defects were repaired with abdominal fat grafts, collagen sponge, titanium mesh, and cerebrospinal fluid diversion. One patient developed a postoperative cerebrospinal fluid leak and meningitis requiring two reoperations to repair, ultimately with fat and fascia lata grafts.

RESULTS:

At 1 year after surgery, both patients have improved compared with their preoperative neurological state, and volume analysis of preoperative and 1-year postoperative magnetic resonance imaging scans confirm a marked reduction in mass effect on the brainstem, with a 78% tumor removal in one patient and 76% removal in the other. Both patients have normal endocrine function.

CONCLUSION:

The endonasal approach offers a minimally invasive, anatomically direct route for removing prepontine epidermoid tumors that obviates brain retraction. The use of angled endoscopes is essential for gaining lateral, cephalad, and caudal visualization to augment the limited microscope view. Inadequate repair of clival dural defects remains the greatest potential pitfall in attempting transsphenoidal transclival tumor removal.
Frontobasal Interhemispheric Trans-Lamina Terminalis Approach for Suprasellar Lesions
Authors: Dehdashti Amir R. , de Tribolet Nicolas
Published: April 2005

THE FRONTOBASAL INTERHEMISPHERIC APPROACH for suprasellar tumors currently incorporates technological advancements and refinements in patient selection, operative technique, and postoperative care. This technique is a valid choice for the removal of suprasellar lesions with extension into the third ventricle without major sequelae related to the surgical approach. The method described here reflects the combination of the frontal interhemispheric and trans-lamina terminalis approaches.
The constructal law of organization in nature: tree-shaped flows and body size
Authors: Bejan Adrian
Published: April 2005

The constructal law is the statement that for a flow system to persist in time it must evolve in such a way that it provides easier access to its currents. This is the law of configuration generation, or the law of design. The theoretical developments reviewed in this article show that this law accounts for (i) architectures that maximize flow access (e.g. trees), (ii)features that impede flow (e.g. impermeable walls, insulation) and (iii)static organs that support flow structures. The proportionality between body heat loss and body size raised to the power 3/4 is deduced from the discovery that the counterflow of two trees is the optimal configuration for achieving(i) and (ii) simultaneously: maximum fluid-flow access and minimum heat leak. Other allometric examples deduced from the constructal law are the flying speeds of insects, birds and aeroplanes, the porosity and hair strand diameter of the fur coats of animals, and the existence of optimal organ sizes. Body size and configuration are intrinsic parts of the deduced configuration. They are results, not assumptions. The constructal law extends physics(thermodynamics) to cover the configuration, performance, global size and global internal flow volume of flow systems. The time evolution of such configurations can be described as survival by increasing performance,compactness and territory.
Circulatory variables and the flight performance of birds
Authors: Bishop Charles M.
Published: April 2005

When considering the `burst' flight performance of birds, such as during take-off, one of the most important structural variables is the ratio of the mass of the flight muscle myofibrils with respect to body mass. However, when considering `prolonged' flight performance the variable of interest should be the body mass ratio of the mass of the flight muscle myofibrils that can be perfused sustainably with metabolites via the blood supply. The latter variable should be related to blood flow (ml min-1), which in turn has been shown to be a function of heart muscle mass, the value of which is more easily obtainable for different species than that for the mass of perfused muscle.

The limited empirical evidence available suggests that for birds and mammals the rate of maximum oxygen consumption scales with heart mass(Mh) as Mh0.88and that for birdsMh scales with body mass (Mb) as Mb0.92, leading to the conclusion that the rate of maximum oxygen consumption in birds scales with an exponent of around Mb0.82. A similar exponent would be expected for the rate of maximum oxygen consumption with respect to the flight muscle mass of birds. This suggests that the sustainable power output from the flight muscles may ultimately be limiting the flight performance of very large flying animals, but as a result of circulatory constraints rather than biomechanical considerations of the flight musclesper se.

Under the particular circumstances of sustainable flight performance,calculations of rates of metabolic energy consumed by the flight muscles can be compared directly with the estimates of biomechanical power output required, as calculated using various aerodynamic models. The difference between these calculated values for rates of energy input and output from the muscles is equivalent to the `apparent' mechanochemical conversion efficiency. The results of one such analysis, of the maximum sustainable flight performance of migratory birds, leads to the conclusion that the efficiency of the flight muscles appears to scale as Mb0.14. However, much of this apparent scaling may be an artefact of the application and assumptions of the models. The resolution of this issue is only likely to come from studying bird species at either extreme of the size range.
The origin of allometric scaling laws in biology from genomes to ecosystems: towards a quantitative unifying theory of biological structure and organization
Authors: West Geoffrey B. , Brown James H.
Published: April 2005

Life is the most complex physical phenomenon in the Universe, manifesting an extraordinary diversity of form and function over an enormous scale from the largest animals and plants to the smallest microbes and subcellular units. Despite this many of its most fundamental and complex phenomena scale with size in a surprisingly simple fashion. For example, metabolic rate scales as the 3/4-power of mass over 27 orders of magnitude, from molecular and intracellular levels up to the largest organisms. Similarly, time-scales (such as lifespans and growth rates) and sizes (such as bacterial genome lengths,tree heights and mitochondrial densities) scale with exponents that are typically simple powers of 1/4. The universality and simplicity of these relationships suggest that fundamental universal principles underly much of the coarse-grained generic structure and organisation of living systems. We have proposed a set of principles based on the observation that almost all life is sustained by hierarchical branching networks, which we assume have invariant terminal units, are space-filling and are optimised by the process of natural selection. We show how these general constraints explain quarter power scaling and lead to a quantitative, predictive theory that captures many of the essential features of diverse biological systems. Examples considered include animal circulatory systems, plant vascular systems, growth,mitochondrial densities, and the concept of a universal molecular clock. Temperature considerations, dimensionality and the role of invariants are discussed. Criticisms and controversies associated with this approach are also addressed.
Study of the influence of nozzle seat type on injection rate and spray behaviour
Authors: Bermúdez V , Payri R , Salvador F J , Plazas A H
Published: April 2005

A deep analysis of the injection rate characteristics and spray behaviour of the most used nozzle types in diesel engines [microSAC and valve covered orifice (VCO)] has been carried out. In order to compare the injection characteristics and the spray behaviour of both nozzle types, several experimental installations were used, such as the steady flow test rig, injection rate test rig, spray momentum test rig, and nitrogen test rig, to obtain a full hydrodynamic and spray characterization. The study of the flow in both nozzles was analysed under steady flow conditions in the steady flow test rig and in real unsteady flow conditions in the injection rate test rig and the spray momentum test rig. The macroscopic properties of the spray (tip penetration and spray cone angle) were characterized using a high-pressure test rig. From the point of view of the internal flow behaviour, the results showed interesting differences in the permeability of both nozzle geometries, with a higher discharge coefficient in the microSAC nozzle. However, from the point of view of air entrainment, the results showed a better quality of fuel-air mixing in the VCO nozzle. Besides the evidence from the experimental results, a theoretical analysis was carried out in order to identify the most important parameters that determine the spray behaviour and thus justify the different macroscopic behaviour of both nozzles.
A Review of Interest and Prices: Foundations of a Theory of Monetary Policy by Michael Woodford
Authors: Green Edward J
Published: April 2005

This is a review article of Interests and Prices: Foundations of a Theory of Monetary Policy (Princeton University Press 2003) by Michael Woodford.
Adsorption Characteristics of o-Phthalic Acid and its Separation by Resins from Maleic Acid and Fumaric Acid in Wastewater
Authors: Zhenghao Fei , Mujun Wang , Jinlong Chen , Yue Sun , Aimin Li , Quanxing Zhang
Published: April 2005

A comparison was made of the adsorption properties towards o-phthalic acid of ND100 resin modified by oxygen groups and ND900 resin modified by amine groups. The work presented focused on various properties including adsorption under static equilibrium conditions, the adsorption thermodynamics and kinetics. In addition, a method was devised for the separation of o-phthalic acid from maleic acid and fumaric acid in wastewater. Two isotherm models (Langmuir and Freundlich) were used to fit the static adsorption results. Both equations fitted the experimental data perfectly. The kinetic results led to the conclusion that the adsorption of o-phthalic acid onto ND900 involved a type of chemical transition.