bluuebunny/crossref_metadata_2025 huggingface dataset:
Donor‐derived myofibroblasts in the ocular surface after allogeneic haematopoietic stem cell transplantation
Authors: Hallberg David , Wernstedt Pernilla , Hanson Charles , Wettergren Yvonne , Stenberg Kristina , Brune Mats , Stenevi Ulf
Published: September 2006

Purpose:  To identify and characterize cells of donor origin in the ocular surface of female recipients who have undergone allogeneic haematopoietic stem cell transplantation (allo‐SCT) from a male donor.

Methods:  Cytological impressions from the eyes of nine allografted patients (17 eyes) were analysed. Donor cells were identified using sex‐chromosome‐specific fluorescence in situ hybridization (FISH). Cells were characterized by immunohistochemistry (IHC) using the CK3 and CK19 epithelial markers, the panleucocytic marker CD45 and the myofibroblast marker α‐SMA.

Results:  No epithelial cells of donor origin were observed in the corneal or conjunctival samples. Cells of donor origin were found in the corneal samples, although these were often too degraded to allow characterization by IHC. In the conjunctiva, a median of 86% of the total number of cells were of recipient origin, including a subgroup (2%) of giant cells exhibiting polyploidy (range 4–18 n), found in the limbal region. Donor cells were detected in the conjunctiva of all nine patients at a median ratio of 9%, of which two‐thirds were CD45+/α‐SMA+.

Conclusions:  We observed superficially located myofibroblasts of donor origin in all allografted patients, but not in samples from healthy controls. Whether myofibroblasts are implicated in ocular graft‐versus‐host disease requires further studies.
Vitrectomy for non‐ischaemic macular oedema in retinal vein occlusion
Authors: Hvarfner Charlotte , Larsson Jörgen
Published: September 2006

Purpose:  To evaluate the effect of vitrectomy in eyes with non‐ischaemic macular oedema secondary to hemi and central retinal vein occlusion.

Methods:  This retrospective study analysed the outcome of eight patients with non‐ischaemic macular oedema without posterior vitreous detachment. Six patients had a central retinal vein occlusion and two had a hemi retinal vein occlusion. A standard three‐port vitrectomy was performed in all patients. Retinal mapping by optical coherence tomography and visual acuity (VA) testing were performed before vitrectomy and at 1, 2 and 12 months postoperatively.

Results:  At the 1‐month follow‐up there was a statistically significant reduction in retinal thickness (Wilcoxon; p = 0.04) that persisted at 2 months (Wilcoxon; p = 0.04). However, at 12 months there was no difference compared with baseline. LogMAR VA was significantly improved at 1 month (Wilcoxon p = 0.04), but at 2 and 12 months there was no difference compared with baseline.

Conclusions:  Vitrectomy in hemi and central retinal vein occlusion has the potential to reduce macular oedema and improve VA in the early postoperative phase but does not seem to improve the longterm outcome of the disease.
The relationship between stress and acute anterior uveitis
Authors: Carrim Zia I. , Ahmed Taha Y. , Taguri Abdel H.
Published: September 2006

Purpose:  To examine the relationship between stress and anterior uveitis using the General Health Questionnaire (GHQ) and the Social Readjustment Rating Questionnaire (SRRQ).

Methods:  Patients attending eye casualty with acute anterior uveitis (AAU) and suitable controls were asked to complete the GHQ and the SRRQ. A follow‐up postal survey, using the same questionnaires, was repeated at least 3 months later amongst AAU patients only. Scores for the GHQ and SRRQ at initial presentation and at follow‐up were compared for different groups.

Results:  Over 12 months, 42 patients and 25 controls participated in the first stage of this study. Patients with AAU had higher GHQ scores than controls (mean 6.8 versus 3.2, p = 0.01). A total of 25 patients responded to the follow‐up postal survey. At follow‐up, 13 had experienced resolution and 12 had recurrence. In the group with resolution, there was a significant fall in GHQ scores (mean 6.1 versus 1.5, p = 0.0044). Patients with recurrence had higher GHQ scores than those with resolution (mean 6.8 versus 1.5, p = 0.02).

Conclusions:  Using the GHQ reveals a clear relationship between stress and the recurrence of AAU in susceptible individuals.
Comparison of the ocular hypotensive effects of bimatoprost and timolol‐dorzolamide combination in patients with elevated intraocular pressure: a 6‐month study
Authors: Ozturk Faruk , Ermis Sıtkı Samet , Inan Umit Ubeyt
Published: September 2006

Purpose:  To compare the ocular hypotensive efficacy and safety of topical bimatoprost and timolol‐dorzolamide combination in patients with primary open‐angle glaucoma (POAG) or ocular hypertension during 6 months of treatment.

Methods:  A sample of 65 patients with a diagnosis of POAG or ocular hypertension were randomized to receive either bimatoprost 0.03% once daily or timolol‐dorzolamide combination twice daily. Study visits occurred at baseline and after 2 weeks and 1, 3 and 6 months of therapy. Intraocular pressure (IOP) measurements were performed at 12.00 hours at all study visits and also at 08.00 hours and 16.00 hours at baseline and 6‐month visits. At each visit, local and systemic side‐effects that occurred during the treatment period were recorded. Student's t‐test was used to compare the differences between IOP values.

Results:  Differences in IOP between the bimatoprost and timolol‐dorzolamide groups were statistically insignificant at all study visits (p > 0.05). In the bimatoprost‐treated group, the IOP reduction was 6.2 ± 1.8 mmHg, whereas it was 6.5 ± 2.3 mmHg in the timolol‐dorzolamide group after 6 months of treatment. The difference was not statistically significant (p = 0.48).

Conclusions:  The IOP‐lowering efficacies of bimatoprost and timolol‐dorzolamide combination were similar over a 6‐month follow‐up. Both bimatoprost and the timolol‐dorzolamide combination were well tolerated. Bimatoprost can be used as a longterm monotherapy agent in the treatment of POAG and ocular hypertension.
Simultaneous quantification of 17 immune mediators in aqueous humour from patients with corneal rejection
Authors: Funding Mikkel , Hansen Troels Krarup , Gjedsted Jakob , Ehlers Niels
Published: September 2006

Purpose:  To simultaneously quantitate and compare the concentrations of 17 immune mediators: (1) the cytokines interleukin‐1β, IL‐2, IL‐4, IL‐5, IL‐6, IL‐7, IL‐10, IL‐12p70, IL‐13, IL‐17, tumour necrosis factor‐α, interferon‐γ; (2) the growth factors granulocyte−monocyte colony‐stimulating factor (GM‐CSF) and granulocyte colony‐stimulating factor (G‐CSF), and (3) the chemokines CXCL‐8, monocyte chemoattractant protein‐1, and macrophage inflammatory protein‐1β in aqueous humour from patients with corneal rejection and patients with a non‐inflammatory condition in the anterior chamber.

Methods:  Aqueous humour was obtained by paracentesis of the anterior chamber in 14 patients with corneal rejection, three patients with cataract and six patients with Fuchs' endothelial dystrophy. Simultaneous quantitation of 17 mediators in 25 µl aqueous humour from each patient was performed by employing a highly sensitive Luminex® 100 multiplex array assay.

Results:  All 17 immune mediators were detected in aqueous humour from rejection patients. The ranges of the immune mediators were determined. The immune mediators were significantly increased in aqueous humour from rejection patients compared with that from other patients.

Conclusions:  The Luminex 100 multiplex array assay is very efficient in simultaneous quantitation of multiple immune mediators in small volumes of aqueous humour. A total of 17 immune mediators were increased in aqueous humour from rejection patients. This underlines the complex immunological interactions of the rejection process.
Significance of cell kinetic parameters in the prognosis of malignant melanoma: a review
Authors: Vereecken Pierre , Laporte Marianne , Heenen Michel
Published: September 2006

Abstract:  Malignant melanoma has been extensively studied concerning methods of predicting progression and clinical outcome. The maximum tumor thickness as measured by Breslow's method is the cornerstone prognostic criterion, but despite this, evolution of the disease in some patients remains unpredictable, confirming that new reliable prognostic factors are awaited. Cell kinetic evaluation has been shown to be a useful tool for assessing the prognosis of breast and gastrointestinal cancer patients. Indeed, in these fields, the mitotic index and MIB‐1 expression index, which are indirect estimates of the growth fraction of tumor cell population, are commonly shown to correlate with tumor grade and patient survival and presented as prognostic factors. In melanoma, results of cell kinetic investigations are conflicting: some studies have established a link between high proliferative activity and a bad prognosis, whereas other reports suggest the opposite. The aim of this review is to discuss these findings.
Are desmoglein autoantibodies essential for the immunopathogenesis of pemphigus vulgaris, or just ‘witnesses of disease'?
Authors: Paus Ralf , Amagai M. , Ahmed A. R. , Kitajima Y. , Bystryn J. C. , Milner Y. , Gniadecki R. , Hertl M. , Pincelli C. , Fridkis‐Hareli M. , Aoyama Y. , Frušić‐Zlotkin M. , Müller E. , David M. , Mimouni D. , Vind‐Kezunovic D. , Michel B. , Mahoney M. , Grando S.
Published: September 2006

Abstract:  Pemphigus vulgaris (PV) is fascinating to dermatologists, epithelial biologists and immunologists alike, as its pathogenesis has been clarified to a much greater extent than that of most other organ‐specific autoimmune diseases, and as it has provided abundant novel insights into desmoglein biology and pathology along the way. Historically, the most influential PV pathogenesis concept is that of Stanley and Amagai. This concept holds that autoantibodies against desmogleins are both essential and sufficient for epidermal blister formation (acantholysis) by impeding the normal functioning of these major adhesion proteins. However, as with most good theories, this landmark concept has left a number of intriguing and important questions open (or at least has not managed to answer these to everyone's satisfaction). Moreover, selected dissenting voices in the literature have increasingly called attention to what may or may not be construed as inconsistencies in this dominant PV pathogenesis paradigm of the recent past. The present debate feature therefore bravely rises to the challenge of re‐examining the entire currently available evidence, as rationally and as undogmatically as possible, by provocatively asking a carefully selected congregation of experts (who have never before jointly published on this controversial topic!) to discuss how essential anti‐desmoglein autoantibodies really are in the immunopathogenesis of PV. Not surprisingly, some of our expert ‘witnesses’ in this animated debate propose diametrically opposed answers to this question. While doing so, incisive additional questions are raised that relate to the central one posed, and our attention is called to facts that may deserve more careful consideration than they have received so far. Together with the intriguing (often still very speculative) complementary or alternative pathogenesis scenarios proposed in the following pages, this offers welcome ‘food for thought’ as well as very specific suggestions for important future research directions – within and beyond the camp of PV aficionados. The editors trust that this attempt at a rational public debate of the full evidence that is currently at hand will constructively contribute to further dissecting the exciting – and clinically very relevant! – immunopathogenesis of PV in all its complexity.
Site‐specific casein kinase 1ε‐dependent phosphorylation of Dishevelled modulates β‐catenin signaling
Authors: Klimowski Laura K. , Garcia Benjamin A. , Shabanowitz Jeffrey , Hunt Donald F. , Virshup David M.
Published: September 2006

Careful regulation of the Wnt–Β‐catenin signaling pathway is critical to many aspects of development and cancer. Casein kinase Iε is a Wnt‐activated positive regulator of this pathway. Members of the Dishevelled family have been identified as key substrates of casein kinase I (CKI). However, the specific sites phosphorylatedin vivoby CKI and their relative importance in the physiologic regulation of these proteins in the canonical Wnt–β‐catenin signaling pathway remain unclear. To address this question, recombinant mouse Dishevelled (mDvl‐1) was phosphorylated by CKIin vitroand phosphorylation sites were identified by MS. CKI phosphorylation of mDvl‐1 at two highly conserved residues, serines 139 and 142, was observed by MS and confirmed by phosphopeptide mapping ofin vivophosphorylated protein. Phosphorylation of these sites is dependent on casein kinase I epsilon activityin vivo. Phenotypic analysis of mutant mDvl‐1 indicates that phosphorylation of these sites stimulates the Dvl‐activated β‐catenin‐dependent Wnt signaling pathway in both cell culture and inXenopusdevelopment. Casein kinase I epsilon is a Wnt‐regulated kinase, and regulated phosphorylation of Dvl allows fine tuning of the Wnt–β‐catenin signaling pathway.
The physiologic role of alternative oxidase in Ustilago maydis
Authors: Juárez Oscar , Guerra Guadalupe , Velázquez Isabel , Flores‐Herrera Oscar , Rivera‐Pérez R. E. , Pardo Juan P.
Published: September 2006

Alternative oxidase (AOX) is a ubiquitous respiratory enzyme found in plants, fungi, protists and some bacterial species. One of the major questions about this enzyme is related to its metabolic role(s) in cellular physiology, due to its capacity to bypass the proton‐pumping cytochrome pathway, and as a consequence it has great energy‐wasting potential. In this study, the physiological role and regulatory mechanisms of AOX in the fungal phytopathogen Ustilago maydis were studied. We found evidence for at least two metabolic functions for AOX in this organism, as a major part of the oxidative stress‐handling machinery, a well‐described issue, and as part of the mechanisms that increase the metabolic plasticity of the cell, a role that might be valuable for organisms exposed to variations in temperature, nutrient source and availability, and biotic or abiotic factors that limit the activity of the cytochrome pathway. Experiments under different culture conditions of ecological significance for this organism revealed that AOX activity is modified by the growth stage of the culture, amino acid availability and growth temperature. In addition, nucleotide content, stimulation of AOX by AMP and respiratory rates obtained after inhibition of the cytochrome pathway showed that fungal/protist AOX is activated under low‐energy conditions, in contrast to plant AOX, which is activated under high‐energy conditions. An estimation of the contribution of AOX to cell respiration was performed by comparing the steady‐state concentration of adenine nucleotides, the mitochondrial membrane potential, and the respiratory rate.
DNA modification with cisplatin affects sequence‐specific DNA binding of p53 and p73 proteins in a target site‐dependent manner
Authors: Pivoňková Hana , Pečinka Petr , Češková Pavla , Fojta Miroslav
Published: September 2006

Proteins p53 and p73 act as transcription factors in cell cycle control, regulation of cell development and/or in apoptotic pathways. Both proteins bind to response elements (p53 DNA‐binding sites), typically consisting of two copies of a motif RRRCWWGYYY. It has been demonstrated previously that DNA modification with the antitumor drug cisplatin inhibits p53 binding to a synthetic p53 DNA‐binding site. Here we demonstrate that the effects of global DNA modification with cisplatin on binding of the p53 or p73 proteins to various p53 DNA‐binding sites differed significantly, depending on the nucleotide sequence of the given target site. The relative sensitivities of protein–DNA binding to cisplatin DNA treatment correlated with the occurrence of sequence motifs forming stable bifunctional adducts with the drug (namely, GG and AG doublets) within the target sites. Binding of both proteins to mutated p53 DNA‐binding sites from which these motifs had been eliminated was only negligibly affected by cisplatin treatment, suggesting that formation of the cisplatin adducts within the target sites was primarily responsible for inhibition of the p53 or p73 sequence‐specific DNA binding. Distinct effects of cisplatin DNA modification on the recognition of different response elements by the p53 family proteins may have impacts on regulation pathways in cisplatin‐treated cells.
A functional polymorphism of apolipoprotein C1 detected by mass spectrometry
Authors: Wroblewski Matthew S. , Wilson‐Grady Joshua T. , Martinez Michael B. , Kasthuri Raj S. , McMillan Kenneth R. , Flood‐Urdangarin Cristina , Nelsestuen Gary L.
Published: September 2006

A survey of plasma proteins in approximately 1300 individuals by MALDI‐TOF MS resulted in identification of a structural polymorphism of apolipoprotein C1 (ApoC1) that was found only in persons of American Indian or Mexican ancestry. MS/MS analysis revealed that the alteration consisted of a T45S variation. The methyl group of T45 forms part of the lipid‐interacting surface of ApoC1. In agreement with an impact on lipid contact, the S45 variant was more susceptible to N‐terminal truncation by dipeptidylpeptidase IV in vitro than was the T45 variant. The S45 protein also displayed greater N‐terminal truncation (loss of Thr‐Pro) in vivo than the T45 variant. The S45 variant also showed preferential distribution to the very‐low‐density lipoprotein fraction than the T45 protein. These properties indicate a functional effect of the S45 variant and support a role for residue 45 in lipid contact and lipid specificity. Further studies are needed to determine the effects of the variant and its altered N‐terminal truncation on the metabolic functions of ApoC1.
Identification of variations in the human phosphoinositide 3‐kinase p110δ gene in children with primary B‐cell immunodeficiency of unknown aetiology
Authors: Jou S.‐T. , Chien Y.‐H. , Yang Y.‐H. , Wang T.‐C. , Shyur S.‐D. , Chou C.‐C. , Chang M.‐L. , Lin D.‐T. , Lin K.‐H. , Chiang B.‐L.
Published: September 2006

Our recent study demonstrated that defects in p110δ result in B‐cell immunodeficiency that is very similar to that observed in BTK‐deficient mice. We revealed that the p110δ fit the B‐cell signal transduction complex and played a non‐redundant role in the development and function of B cells. In humans, most children with primary B‐cell immunodeficiency have mutations in the BTK, whereas a few have defects in the components of the B‐cell signal transduction complex. But little is known about the genetic variation of p110δ in children with defects in B‐cell immunodeficiency of unknown aetiology. Sixteen patients from 15 unrelated families and 112 normal controls underwent sequence analysis to identify genetic variations of the p110δ. Allele frequency in each group was also analysed and compared. We identified five single base‐pair polymorphic nucleotide exchanges in both patient and control groups with similar allele frequencies, which did not contribute to the immunodeficiency. Three of them are novel (m.953A>G, m.1200C>T and m.1561A>G), and the m.953A>G and m.1561A>G nucleotide exchanges are non‐synonymous (N253S and T456A, respectively). The novel m.1561A>G was in complete linkage disequilibrium with the known m.873A>G in our study of Taiwanese group. In addition, one novel single base‐pair missense mutation, m.3256G>A (E1021K), was identified in one boy with typical clinical features of primary B‐cell immunodeficiency and could not be found in either his family or the normal control population. By atomic structural analysis of the amino acid as well as the alignment comparison between species, it resulted in the replacement of the negative‐charged amino acid E with the positive‐charged amino acid K at codon 1021, located in the highly conservative and important catalytic functional domain. Our findings could shed light on further understanding the polymorphisms of p110δ in B‐cell immunodeficiency and different populations. Moreover, the 3256G>A missense mutation raised the attention and warranted further extensive analysis to elucidate the role of p110δ in human immunodeficiency.
Map of the Galaxy in the 6.7-keV emission line
Authors: Revnivtsev M. , Molkov S. , Sazonov S.
Published: September 2006

We study the two-dimensional surface brightness distribution of the Galactic X-ray background emission outside the central degree around Sgr A* in the 6.7-keV line as measured by the Proportional Counter Array spectrometer of the Rossi X-ray Timing Explorer observatory. The use of the emission line instead of continuum (3–20 keV) radiation and application of time-variability filtering to the long data set allows us to strongly suppress the contamination of the Galactic ridge X-ray emission (GRXE) map by bright point-sources. The surface brightness in the 6.7-keV line demonstrates very good correspondence with the near-infrared surface brightness over the whole Galaxy, supporting the notion that the GRXE consists mostly of integrated emission from weak Galactic X-ray sources. We find compatible linear correlations between near-infrared and 6.7-keV surface brightness for the bulge and disc of the Galaxy. This indicates that the populations of weak X-ray sources making up the GRXE in the disc and in the bulge are not significantly different.
Quality and Microbial Population of Cornish Game Hen Carcasses as Affected by Electron Beam Irradiation
Authors: Gomes C. , Da Silva P.F. , Castell‐Perez M.E. , Moreira R.G.
Published: September 2006

ABSTRACT:  We evaluated the chemical and microbiological quality of Cornish game hen carcasses irradiated up to 7 kGy with a 10 MeV linear accelerator (dual beam configuration). Eighty frozen and vacuum packaged (approximately 0.45 kg) Cornish game hens (Gallus domesticus) were irradiated and stored in low‐density polyethylene bags at 4 ± 1 °C for 21 d; nonirradiated chickens served as controls. Fat oxidation (in terms of malonaldehyde content) increased with storage time and dose for all chicken parts analyzed (breast, thigh, and skin). As expected, the skin had the highest level of fat oxidation while the breast samples had the lowest. Oxidation level in all samples exposed to 2 kGy reached a maximum on day 14. Sensory evaluation showed that irradiation caused significant textural toughening, and increased the redness of raw chicken meat. In terms of overall quality and aroma, lipid oxidation was not a major problem since it was not detected by the panelists. Irradiation significantly reduced the total viable microbial counts (TVC) in the breast and thigh samples. Exposure to 3‐kGy dose decreased the TVC by 0.3‐log cycles on the surface of the skin. In less than 14 d, the nonirradiated chicken carcasses had counts greater than 6 log CFU/50 cm2, while the 2 and 3 kGy irradiated samples reached these numbers only after 21 d of storage. Samples irradiated at 7 kGy had consistently the lowest counts (2.5 log CFU/50 cm2) throughout storage time.This study shows that irradiation up to 7 kGy and refrigerated storage (4 °C) inhibits microbial growth and extends shelf life of Cornish game hens without affecting consumers' acceptability.
Modeling the Growth Rate of Listeria Monocytogenes Using Absorbance Measurements and Calibration Curves
Authors: Valero A. , Pérez‐Rodríguez F. , Carrasco E. , García‐Gimeno R.M. , Zurera G.
Published: September 2006

ABSTRACT:  The influence of environmental conditions (temperature and pH) on the relationship between growth data expressed by absorbance (ABS) and data transformed to cell count (CC) measurements was studied, using calibration curves for predicting Listeria monocytogenes growth rate. With this aim, 19 calibration curves at different stress conditions were performed. A shift in the calibration curves was observed for the most stringent conditions, which affected cell viability. Subsequently, a Baranyi model was fitted to ABS and CC data to obtain growth rate (GRABS and GRCC) and a linear regression was performed. Absorbance was found to be a reliable technique for measuring microbial growth, as a strong relationship between GRABS and GRCC (R2= 0.9717) was observed. Furthermore, 2 different response surface models were developed to link GRABS and GRCC data with temperature, citric acid, and ascorbic acid. The goodness of fit of both ABS and CC models to the data was observed (RMSE = 0.0223 and 0.0221; SEP [%]= 29 and 25, respectively). Mathematical validation was carried out by calculating bias and accuracy factors, providing reasonably acceptable values for both absorbance and cell count models (Bf= 1.11 and 1.09, Af= 1.44 and 1.41, respectively). Predictions for GRCC were compared to data taken from Growth Predictor software at different temperatures and pH. Response surface model predictions showed that a suitable combination of preservative factors can inhibit L. monocytogenes growth. These results highlight accurate predictions of growth parameters of L. monocytogenes.
Lubrication of Oral Surfaces by Food Emulsions: the Importance of Surface Characteristics
Authors: De Hoog Els H. A. , Prinz Jon F. , Huntjens Linda , Dresselhuis Diane M. , Van Aken George A.
Published: September 2006

ABSTRACT:  The friction between surfaces in relative motion lubricated by food emulsions has been measured. Different types of surfaces were tested, including metal, glass, rubber, and mucosal surfaces (pig tongue and pig esophagus). We demonstrate that the load‐dependent behavior of the coefficient of kinetic friction was different for various types of surfaces used; it decreased with increasing load for the mucosal surfaces, but was constant for glass‐metal surfaces. We show that this difference is an effect of the roughness and the deformability of the surfaces. For mucosal surfaces, the friction force did not depend on the oil fraction in the measured range of 10% to 40% (w/w). Furthermore, 3 commercial dairy products were tested between these surfaces. The lubrication properties of the low‐fat (1.5% fat content) and high‐fat (3.5% fat content) milk were comparable to those of the model emulsions. However, the friction force of the commercial cream (35% fat content) was found to be much lower.
Relative myotoxic and haemodynamic effects of the β‐agonists fenoterol and clenbuterol measured in conscious unrestrained rats
Authors: Burniston Jatin G. , Tan Lip‐Bun , Goldspink David F.
Published: September 2006

The β2‐adrenoceptor (β2‐AR) agonists clenbuterol and fenoterol have similar beneficial effects in animal models of heart failure. However, large doses of clenbuterol can induce cardiomyocyte death, and it is not known which of these agents has the most favourable therapeutic profile. We have investigated the cardiotoxicity of clenbuterol and fenoterol alongside that of isoprenaline, and compared their haemodynamic effects. Wistar rats (n= 6 per group) were subcutaneously injected with each β‐agonist (0.003–3 mmol kg−1) or saline, and cardiomyocyte apoptosis was detected by caspase 3 immunohistochemistry. In a separate experiment, rats (n= 4) were given equivalent doses to those used in the myotoxicity studies, in a randomized cross‐over design, and their blood pressure recorded via radiotelemetry. Injection of 0.3 mmol kg−1 fenoterol or isoprenaline, but not clenbuterol, induced significant cardiomyocyte apoptosis (0.4 ± 0.05%; P < 0.05). At 3 mmol kg−1, all agonists induced apoptosis (fenoterol, 1.1 ± 0.1%; isoprenaline, 0.9 ± 0.8%; and clenbuterol, 0.4 ± 0.07%; P < 0.05). β1‐Adrenoceptor antagonism (10 mg kg−1 bisoprolol) prevented 92% (P < 0.05) of apoptosis induced by all three agonists, but clenbuterol‐induced apoptosis could also be prevented by 96% (P < 0.05) by β2‐AR antagonism (10 mg kg−1 ICI 118 551). Clenbuterol decreased diastolic (1.3‐ to 1.6‐fold; P < 0.05) and systolic blood pressure (1.3‐fold; P < 0.05), and doses > 0.3 mmol kg−1 increased heart rate (1.4‐fold; P < 0.05). Fenoterol increased heart rate (1.2‐ to 1.4‐fold; P < 0.05), and doses > 0.3 mmol kg−1 decreased diastolic blood pressure (1.3‐fold; P < 0.05). In conclusion, the cardiotoxicity of fenoterol was similar to isoprenaline and greater than clenbuterol, and fenoterol had less desirable haemodynamic effects.
Inactivation of nitric oxide by rat cerebellar slices
Authors: Hall C. N. , Garthwaite J.
Published: September 2006

Nitric oxide (NO) functions as an intercellular messenger throughout the brain. For this role to be performed efficiently, there must be a mechanism for neutralizing NO, but whether an active biological process exists, or whether NO is lost mainly through diffusion is unclear. To investigate this issue, rat cerebellar slices were exposed to constant levels of NO and the cGMP generated within the slice used as an indicator of NO concentrations therein. NO was about 1000‐fold less potent in slices (EC50, 1 μm) than in separated cells from the same tissue (EC50, 1.6 nm), consistent with access of NO to the slice interior being greatly hindered by inactivation. Supporting this interpretation, immunohistochemical analysis indicated a marked concentration gradient of cGMP across the thickness of slices exposed to subsaturating NO concentrations, signifying a marked NO gradient. Several known NO‐degrading processes, including reaction with lipid peroxyl radicals, erythrocytes and superoxide ions, were eliminated as contributing factors, indicating a novel mechanism. A diffusion–inactivation model was used to estimate the kinetics of NO consumption by the slices. The best fits to experimental data indicated a Michaelis‐Menten‐type reaction having a Vmax of 1–2 μm s−1 and a Km of around 10 nm. The rates predict that inactivation would impose a very short half‐life (<10 ms) on NO in physiological concentrations (up to 10 nm) and that it would play an important role in shaping the NO concentration profiles when it is synthesized by multiple nearby sites.
Inlet Fogging of Gas Turbine Engines: Climatic Analysis of Gas Turbine Evaporative Cooling Potential of International Locations
Authors: Chaker Mustapha , Meher-Homji Cyrus B.
Published: September 2006

Inlet fogging of gas turbine engines has attained considerable popularity due to the ease of installation and the relatively low first cost compared to other inlet cooling methods. With increasing demand for power and with shortages envisioned especially during the peak load times during the summers, there is a need to boost gas turbine power. There is a sizable evaporative cooling potential throughout the world when the climatic data is evaluated based on an analysis of coincident wet bulb and dry bulb information. These data are not readily available to plant users. In this paper, a detailed climatic analysis is made of 106 major locations over the world to provide the hours of cooling that can be obtained by direct evaporative cooling. This data will allow gas turbine operators to easily make an assessment of the economics of evaporative fogging. The paper also covers an introduction to direct evaporative cooling and the methodology and data analysis used to derive the cooling potential. Simulation runs have been made for gas turbine simple cycles showing effects of fogging for a GE Frame 7EA and a GE Frame 9FA Gas turbine for 60 and 50 Hz applications.
An Adaptation Approach for Gas Turbine Design-Point Performance Simulation
Authors: Li Y. G. , Pilidis P. , Newby M. A.
Published: September 2006

Accurate simulation and understanding of gas turbine performance is very useful for gas turbine users. Such a simulation and performance analysis must start from a design point. When some of the engine component parameters for an existing engine are not available, they must be estimated in order that the performance analysis can be carried out. However, the initially simulated design-point performance of the engine using estimated engine component parameters may give a result that is different from the actual measured performance. This difference may be reduced with better estimation of these unknown component parameters. However, this can become a difficult task for performance engineers, let alone those without enough engine performance knowledge and experience, when the number of design-point component parameters and the number of measurable/target performance parameters become large. In this paper, a gas turbine design-point performance adaptation approach has been developed to best estimate the unknown design-point component parameters and match the available design-point engine measurable/target performance. In the approach, the initially unknown component parameters may be compressor pressure ratios and efficiencies, turbine entry temperature, turbine efficiencies, air mass flow rate, cooling flows, bypass ratio, etc. The engine target (measurable) performance parameters may be thrust and specific fuel consumption for aero engines, shaft power and thermal efficiency for industrial engines, gas path pressures and temperatures, etc. To select, initially, the design point component parameters, a bar chart has been used to analyze the sensitivity of the engine target performance parameters to the design-point component parameters. The developed adaptation approach has been applied to a design-point performance matching problem of an industrial gas turbine engine GE LM2500+ operating in Manx Electricity Authority (MEA), UK. The application shows that the adaptation approach is very effective and fast to produce a set of design-point component parameters of a model engine that matches the actual engine performance very well. Theoretically, the developed techniques can be applied to other gas turbine engines.
Profiling of Redox Atmosphere in Flames by Chemical Seeding/Planar Laser-Induced Fluorescence (CS/PLIF)
Authors: Kitagawa K. , Itoh S. , Arai N. , Gupta Ashwani K.
Published: September 2006

Knowledge on the local value of reducing and oxidizing (redox) atmospheres in flames is among the most important issues to be desired by combustion engineers. In this study, the spatial distribution of a redox atmosphere in flames has been measured experimentally by the chemical seeding/laser-induced fluorescence (CS/LIF) technique. A solution of iron was sprayed into a premixed propane-air flame supported on a slot burner. The LIF intensity of FeO band was compared to that of a Fe line to estimate the experimentally determined degree of atomization in the reaction FeO→Fe+O. The flame temperature profile was determined as a rotational temperature and was obtained by comparing the LIF (laser-induced fluorescence) intensities of OH rotational lines. The degree of atomization was theoretically calculated on the basis that simple thermal dissociation takes place in the reaction. The redox atmosphere, or a redox index, is defined as the ratio of the experimentally determined to theoretically calculated degrees of atomization. Two-dimensional distributions or profiles of the excitation temperature, experimentally determined degree of atomization, and redox index have been measured using a charge coupled device (CCD) camera fitted with an optical bandpass filter and the associated signal processing using a computer. This method has been successfully applied to quantitatively illustrate the local atmosphere and profile of the redox atmosphere in flames.
A Profit-Based Approach for Gas Turbine Power Plant Outage Planning
Authors: Zhao Yongjun , Volovoi Vitali , Waters Mark , Mavris Dimitri
Published: September 2006

Traditionally, for complicated systems, such as a gas turbine power plant, maintenance cost and online availability are two of the most important concerns to the equipment owner. However, in the deregulated electric power market, cost and reliability are not the only concerns. The ultimate goal is to maximize plant profitability, and this requires the evaluation of many different factors, including system performance, the aging and reliability of equipment, maintenance practices, and market dynamics accounting for the price and availability of fuel as well as the generation of revenues in competing markets. Thus, gas turbine power plant planning optimization is a complex problem, and comprehensive operational modeling and optimization methods are required. In this paper, a profit-based power plant outage planning approach is presented that reflects the new challenges posed by deregulation. Specifically, particular attention is paid to modeling power plant aging, performance degradation, reliability deterioration, and, importantly, the energy market dynamics. A multiple time-scale method is developed for coupled short-term, long-term generation scheduling and outage planning for this profit-based outage planning approach. The procedure is implemented for a base load combined cycle power plant with a single gas turbine, with the results demonstrating the feasibility of the proposed approach.
Rotordynamic Coefficients Measurements Versus Predictions for a High-Speed Flexure-Pivot Tilting-Pad Bearing (Load-Between-Pad Configuration)
Authors: Al-Ghasem Adnan M. , Childs Dara W.
Published: September 2006

Experimental dynamic force coefficients are presented for a four pad flexure-pivot tilting-pad bearing in load-between-pad configuration for a range of rotor speeds and bearing unit loadings. Measured dynamic coefficients have been compared to theoretical predictions using an isothermal analysis for a bulk-flow Navier-Stokes (NS) model. Predictions from two models—the Reynolds equation and a bulk-flow NS equation models are compared to experimental, complex dynamic stiffness coefficients (direct and cross-coupled) and show the following results: (i) The real part of the direct dynamic-stiffness coefficients is strongly frequency dependent because of pad inertia, support flexibility, and the effect of fluid inertia. This frequency dependency can be accurately modeled for by adding a direct added-mass term to the conventional stiffness/damping matrix model. (ii) Both models underpredict the identified added-mass coefficient (∼32kg), but the bulk-flow NS equation predictions are modestly closer. (iii) The imaginary part of the direct dynamic-stiffness coefficient (leading to direct damping) is a largely linear function of excitation frequency, leading to a constant (frequency-independent) direct damping model. (iv) The real part of the cross-coupled dynamic-stiffness coefficients shows larger destabilizing forces than predicted by either model. The frequency dependency that is accounted for by the added mass coefficient is predicted by the models and arises (in the models) primarily because of the reduction in degrees of freedom from the initial 12 degrees (four pads times three degrees of freedom) to the two-rotor degrees of freedom. For the bearing and condition tested, pad and fluid inertia are secondary considerations out to running speed. The direct stiffness and damping coefficients increase with load, while increasing and decreasing with rotor speed, respectively. As expected, a small whirl frequency ratio (WFR) was found of about 0.15, and it decreases with increasing load and increases with increasing speed. The two model predictions for WFR are comparable and both underpredict the measured WFR values. Rotors supported by either conventional tilting-pad bearings or flexure-pivot tilting-pad (FPTP) bearings are customarily modeled by frequency-dependent stiffness and damping matrices, necessitating an iterative calculation for rotordynamic stability. For the bearing tested and the load conditions examined, the present results show that adding a constant mass matrix to the FPTP bearing model produces an accurate frequency-independent model that eliminates the need for iterative rotordynamic stability calculations. Different results may be obtained for conventional tilting-pad bearings (or this bearing at higher load conditions).
Flow Stability of Heat Recovery Steam Generators
Authors: Walter Heimo , Linzer Wladimir
Published: September 2006

This paper presents the results of theoretical flow stability analyses of two different types of natural circulation heat recovery steam generators (HRSG)—a two-drum steam generator—and a HRSG with a horizontal tube bank. The investigation shows the influence of the boiler geometry on the flow stability of the steam generators. For the two-drum boiler, the steady-state instability, namely, a reversed flow, is analyzed. Initial results of the investigation for the HRSG with a horizontal tube bank are also presented. In this case, the dynamic flow instability of density wave oscillations is analyzed.
Influence of Valve Lift and Throttle Angle on Intake Flow in a High-Performance Four-Stroke Motorcycle Engine
Authors: Algieri Angelo , Bova Sergio , De Bartolo Carmine
Published: September 2006

A high-performance four-stroke motorcycle engine was analyzed at a steady flow rig. The aim of the work was to characterize the fluid dynamic behavior of the engine head during the intake phase. To this purpose a twofold approach was adopted: the dimensionless flow coefficient was used to evaluate the global breathability of the intake system, while the laser doppler anemometry (LDA) technique was employed to define the flow structure within the combustion chamber. The analysis gave evidence of two contrarotating vortices with axes parallel to the cylinder axis and showed variations in the flow structure when moving away from the engine head. Furthermore, the study highlighted the great influence of the throttle angle on the head fluid dynamic efficiency and how this influence changes with the valve lift. Experimental data were correlated by a single curve adopting a new dimensionless plot. Moreover, LDA measurements were used to evaluate the angular momentum of the flux and an equivalent swirl coefficient, and to correlate them to a previous global swirl characterization carried out on the same engine head using an impulse swirl meter.
Soot Formation Study in a Rapid Compression Machine
Authors: Kitsopanidis I. , Cheng W. K.
Published: September 2006

A rapid compression machine was used to study the soot formation process under diesel enginelike conditions. The apparatus creates accurately controlled conditions at the end of compression (uniform mixture, temperature, and well-defined mixture composition) and, by decoupling chemistry with mixing, provides an unambiguous data interpretation for kinetics study. The soot evolution was studied by the line-of-sight absorption method (at 632.8nm), which measured the soot volume concentration evolution in the initial stage of soot growth before the optical path became opaque. For a rich butane mixture at fuel equivalence ratio of 3, the ignition delay showed a negative temperature dependence at intermediate temperatures. The soot volume fraction showed an initial exponential growth, with a growth rate depending on the compressed charge fuel concentration. A substantial amount of soot was formed after the soot cloud became opaque. By weighing the total soot particles after the experiment, only ∼10-15% of the soot mass was formed when the beam transmission was reduced to 5%. The final soot mass was ∼15-18% of the total carbon mass for compressed charge density of 250mol∕m3 and temperature from 740to930K.
Fluid Flow and Heat Transfer in Power-Law Fluids Across Circular Cylinders: Analytical Study
Authors: Khan W. A. , Culham J. R. , Yovanovich M. M.
Published: September 2006

An integral approach of the boundary layer analysis is employed for the modeling of fluid flow around and heat transfer from infinite circular cylinders in power-law fluids. The Von Karman-Pohlhausen method is used to solve the momentum integral equation whereas the energy integral equation is solved for both isothermal and isoflux boundary conditions. A fourth-order velocity profile in the hydrodynamic boundary layer and a third-order temperature profile in the thermal boundary layer are used to solve both integral equations. Closed form expressions are obtained for the drag and heat transfer coefficients that can be used for a wide range of the power-law index, and generalized Reynolds and Prandtl numbers. It is found that pseudoplastic fluids offer less skin friction and higher heat transfer coefficients than dilatant fluids. As a result, the drag coefficients decrease and the heat transfer increases with the decrease in power-law index. Comparison of the analytical models with available experimental/numerical data proves the applicability of the integral approach for power-law fluids.
Heat Transfer Enhancement by EHD-Induced Oscillatory Flows
Authors: Lai F. C. , Mathew J.
Published: September 2006

Prior numerical solutions of electrohydrodynamic (EHD) gas flows in a horizontal channel with a positive-corona discharged wire have revealed the existence of steady-periodic flows. It is speculated that heat transfer by forced convection may be greatly enhanced by taking advantage of this oscillatory flow phenomenon induced by electric field. To verify this speculation, computations have been performed for flows with Reynolds numbers varying from 0 to 4800 and the dimensionless EHD number (which signifies the effect of electric field) ranging from 0.05 to ∞. The results show that heat transfer enhancement increases with the applied voltage. For a given electric field, oscillation in the flow and temperature fields occurs at small Reynolds numbers. Due to the presence of oscillatory secondary flows, there is a significant enhancement in heat transfer.
The Electro-Adsorption Chiller: Performance Rating of a Novel Miniaturized Cooling Cycle for Electronics Cooling
Authors: Ng K. C. , Sai M. A. , Chakraborty A. , Saha B. B. , Koyama S.
Published: September 2006

The paper describes the successful amalgamation of the thermoelectric and the adsorption cycles into a combined electro-adsorption chiller (EAC). The symbiotic union produces an efficiency or COP (coefficient of performance) more than threefold when compared with their individual cycles. The experiments conducted on the bench-scale prototype show that it can meet high cooling loads, typically 120W with an evaporator foot print of 25cm2, that is 5W∕cm2 at the heated surface temperature of 22°C, which is well below that of the room temperature. The COPs of the EAC chiller vary from 0.7 to 0.8, which is comparable to the theoretical maximum of about 1.1 at the same operating conditions. With a copper-foam cladded evaporator, the high cooling rates have been achieved with a low temperature difference. In addition to meeting high cooling rates, the EAC is unique as (i) it has almost no moving parts and hence has silent operation, (ii) it is environmentally friendly as it uses a nonharmful adsorbent (silica gel), and (iii) water is used as the refrigerant.