bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictive value of a dexamethasone provocative test prior to intravitreal triamcinolone acetonide injection
Authors: ZEYEN T , BREUSEGEM C , VANDEWALLE E , VAN CALSTER J , FIEUWS S , STALMANS I
Published: September 2008

Purpose To investigate the diagnostic value of a topical dexamethasone (DXM) provocative test for steroid‐induced ocular hypertension after intravitreal triamcinolone acetonide (IVTA) injection.

Methods Patients scheduled for IVTA received DXM 4x over 4 weeks. IVTA was injected in those with no or moderate DXM steroid response (6 mmHg≤IOP rise≤15 mm Hg). High DXM steroid responders (IOP rise>15 mmHg) received no IVTA and were subsequently excluded. IOP was measured at baseline, 4 weeks after DXM drops, and at day 1, weeks 1, 2, and 4, and months 3 and 6 following IVTA.

Results Thirty‐six patients (36 eyes) were included. After the DXM test, 4 patients (11%) and 2 patients (5%) were moderate and high steroid responders, respectively. After IVTA, 12 patients (33%) and 4 patients (11%) were moderate and high steroid responders, respectively. The DXM test had a sensitivity of 25% (95%CI[0.07,0.52]), a specificity of 100% (95%CI[0.83,1.00]), a positive predictive value of 100% (95%CI[0.40,1.00]), and a negative predictive value of 62% (95%CI[0.44,0.79]) for a moderate to high steroid response after IVTA. The IOP rise after IVTA was significantly higher in previous topical DXM responders vs. DXM nonresponders, 17.0±7.8 mmHg vs. 5.0±4.4 mmHg, respectively (P=.005, Mann Whitney U).

Conclusion We found a low sensitivity, a high specificity, a high positive predictive value and a moderate negative predictive value for the topical DXM provocative test with regard to a steroid response after IVTA. These findings indicate that a topical DXM test is clinically useful in predicting steroid response after IVTA. However, a negative DXM provocative test does not rule out steroid response after IVTA.
Eye‐derived systemic immune regulation : ACAID
Authors: TAKEUCHI M
Published: September 2008

A form of systemic tolerance is created when antigenic material is placed in the anterior chamber of the eye, an immune privileged site. Termed anterior chamber associated immune deviation (ACAID), this form of tolerance insures that the systemic immune response to eye‐derived antigens is devoid of T cells that mediate delayed hypersensitivity and antibodies that fix complement. ACAID arises when antigen is captured by intraocular antigen presenting cells, then carried to the spleen where a microenvironment is created that activates antigen‐specific T cells to differentiate into regulatory cells that interfere with the induction of delayed hypersensitivity as well as its expression. Several cytokines and neuropeptides, constitutively present in the aqueous humor of the eye, imposes distinctive properties on antigen presenting cells, which play primary roles to the induction of ACAID. In this SIS, I would like to provide up‐to‐date information of what kinds of diseases ACAID can be effective for and whether human monocytes can acquire the specific functions as ACAID‐inducing antigen presenting cells, in addition to molecules, cells, and concepts newly recognized as contributing to tolerance induction induced in ACAID. Evidence is given to support the idea that application of such information may lead to potential for therapeutic applications of ACAID mechanisms in prevention of progression of immune‐inflammatory diseases in humans.
Role of ocular pigment epithelial cells in regional ocular immunity
Authors: SUGITA S , MOCHIZUKI M
Published: September 2008

Purpose To whether soluble factors by retinal pigment epithelial cells (RPE) promote the generation of T regulatory cells in vitro.

Methods Primary cultured RPE cells were established from normal C57BL/6 mice. T cells were co‐cultured with RPE, x‐irradiated, and used as regulators (RPE Treg cells). Target bystander T cells were established from normal splenic T cells with anti‐CD3 antibodies. T‐cell activation was assessed for proliferation by [3H]–thymidine incorporation. Expression of cytotoxic T lymphocyte antigen‐2α (CTLA‐2α) and cathepsin L on RPE and T cells was evaluated with oligonucleotide microarray, RT‐PCR, immune staining, western blots and flow cytometry. Recombinant mouse CTLA‐2α and anti‐mouse CTLA‐2α abs were used for the assay. For induction of experimental autoimmune uveitis (EAU), mice were immunized with interphotoreceptor retinoid‐binding protein peptide emulsified in complete Freund’s adjuvant.

Results RPE converted CD4+ T cells into Treg cells by producing and secreting CTLA‐2α, a cathepsin L inhibitor. CTLA‐2α secreted by RPE cells selectively inhibited cathepsin L in the T cells and the cathepsin L‐lacking T cells exhibited Treg phenotype, i.e. expression of Foxp3 and production of transforming growth factor beta (TGFβ). CTLA‐2α enhanced their production of active forms of TGFβ. In addition, CD4+ T cells from EAU‐induced cathepsin L knockout (KO) donors contained high population of Foxp3+ T cells and EAU in cathepsin L KO mice was significantly less than those in wild type mice. Furthermore, treatment with recombinant CTLA‐2α significantly suppressed EAU.

Conclusion These results indicate that immunosuppressive factors derived from RPE participate in the establishment of immune regulation in the posterior segment of the eye.
Molecular diagnosis of X‐linked retina diseases
Authors: HARDCASTLE AJ
Published: September 2008

Purpose X‐linked retinal dystrophies present as clinically severe in affected males, whereas heterozygous carrier females show a wide spectrum of clinical signs from normal to marked abnormalities. A range of phenotypes will be discussed, and phenotype/genotype correlation explored.

Methods Patient DNA was analysed for mutations in X‐linked genes by a combination of PCR and sequencing. Clinical tests included fundus examination and ERG recordings.

Results Molecular screening has resulted in identification of the causative mutation in many cases. Interpretation of the pathogenicity of a sequence alteration can be problematic in the absence of a functional test for sequence changes. Examples of mutations identified will be presented with associated clinical outcomes, with particular emphasis on RPGR as a cause of retinitis pigmentosa, cone‐rod dystrophy, or syndromic RP.

Conclusion A molecular diagnosis is often necessary to determine carrier status of at risk females in X‐linked pedigrees. Phenotypes vary between and within families with mutations in the genes RPGR and RP2. However, phenotype and genotype can be correlated for X‐linked congenital stationary night blindness caused by mutations in the NXY and CACNA1F genes.
Optimisation of diagnostic strategy in severe ocular sicca syndrome
Authors: DE MONCHY I , MARIETTE X , GENDRON G , OFFRET H , LABETOULLE M
Published: September 2008

Purpose To define the interest of phenol red thread in diagnosis of ocular sicca syndrome, and to estimate the agreement with the Schirmer I test.

Methods The PRT test was performed before (PRT1) and after (PRT2) the Schirmer I test, in both eyes of 72 patients complaining of ocular dryness secondary to Sjögren’s syndrome, 71 patients with Sicca Asthenia Polyalgia Syndrome and 40 healthy volunteers. Only the lowest result for each test was used in statistical analysis and cut‐off values were determined using the Receiver Operating Curve procedure. Groups were matched by age and sex.

Results The ROC procedure showed weak sensitivity/specificity couples whatever PRT1 cut‐off value. A cut‐off value of 15mm for PRT2 provided the best ratio between sensitivity and specificity (68% and 90% respectively) and 10mm for Schirmer I test permitted a sensitivity of 77.80% and specificity of 82.50%. Maximal agreement between PRT2 and Schirmer I test was found for a PRT2 value of 15mm with however a mean agreement (Kappa index~ 0.5); however none of PRT2 test alone or Schirmer I test alone was better than the other for diagnosis of ocular sicca syndrome. In contrast, the combination of Schirmer I test (≤10mm), PRT2 test (≤15mm) and negative“deltaPRT” (PRT2 < PRT1) permitted to increase sensitivity and specificity to 92% and 95%, respectively.

Conclusion Schirmer I test must certainly be used firstable in diagnostic step. However PRT2 and negative « deltaPRT » permit classification of patients « forgotten » by Schirmer I test. Finally, association Schirmer I test, PRT2 and negative « deltaPRT » offers characteristics of diagnostic test (high specificity (90%) and sensitivity (85%)) with a high positive predictive value (73, 3%) for SGS.
Tufting enteropathy: ocular surface and conjunctival markers
Authors: BREMOND‐GIGNAC D , COPIN H , BRIGNOLE‐BAUDOUIN F , MILAZZO S , BAUDOUIN C
Published: September 2008

Purpose to describe clinical impairment and ocular surface anomalies in a case of tufting enteropathy (intestinal epithelial dysplasia) and to characterized conjunctival markers

Methods We studied a case of a 5 year‐old girl presenting a tufting enteropathy which is a rare congenital disease with persistent diarrhea. Systemic anomalies were associated. She presented a tearing since 8 months‐old. At 5 years old she developed a marked keratitis with itching and blepharospasm non‐responding to treatment. At fundus a unilateral coloboma was noted. Conjunctival impression cytology specimen were processed and markers were analyzed using flow cytometry and were expressed by determining the percentage of cells expressing the markers. CC chemokine receptor 4 (CCR4), CC chemokine receptor 5 (CCR5) expression and HLA‐DR were studied. Conjunctival biopsies were studied in optical microscopy.

Results Markers obtained with conjunctival impression cytology specimens were described showing CCR4 CCR4 was overexpressed related to the Th2 inflammatory pathways. More than 60% are associated with a non specific keratitis. Allergic and dry eye syndrome could be both implicated in the mechanism of the keratitis. Conjunctival biopsy showed acute inflammation of the conjunctiva with epithelial cells exfoliation. This typical aspect of the conjunctiva could be related with the observed disorganization of surface enterocytes with focal crowding forming tuft.

Conclusion A better understanding of ocular surface disorders in tufting enteropathy might help to elucidate the molecular mechanisms of corneal and intestinal epithelial diseases.
In vitro contact angle and coefficient of friction profiles for daily disposable contact lenses
Authors: GILES TG
Published: September 2008

Purpose To profile coefficient of friction (COF) and contact angle (CA) performance of popular daily disposable contact lenses many of which contain comfort additives. COF indicates the level of friction that may be experienced between a contact lens and ocular surfaces (corneal epithelium and palpebral conjunctiva). Small CA values indicate a more wettable lens surface.

Methods CA's and static and dynamic COF's were measured on commercially available nelfilcon A with PVA (NA); nelfilcon A with HPMC, PEG and PVA (NB); etafilcon A with added povidone (E); hilafilcon B (H); and omafilcon A (O) contact lenses. Lenses were removed from the original packages and measured for out of package (TO) or rinsed in PBS for 1 hour (T1) or 4 hours (T4) and measured. Unpaired t‐tests with alpha <0.05 were used to compare between and within lenses and report statistically significant differences.

Results At TO, the CA's averaged NA (9.6), NB (11.4), E (39.6), H (11.2), and O (44.6). After rinsing the NA and NB lenses maintained the lowest CA's. The highest CA was with E at T4 (78.2). At TO, the lowest static and kinetuc COF's were measured on NA (0.006 and 0.027 respectively) while the highest static and kinetic COF's were measured on O (0.831 and 1.114). After rinsing, static COF's were statistically unchanged for NB and O (which contains no comfort additives) and all others increased at T1 and T4 from their T0 values.

Conclusion The contact angle and friction performance of daily disposable contact lenses was found to vary widely. Nelfilcon A with PVA were the most wettable as indicated by having the lowest CA. Nelfilcon A with PVA, PEG and HPMC showed low static and kinetic COF's that remained stable with rinsing.

Commercial interest
Intracameral cefuroxime: evaluation of stability in normal saline and balanced salt solutions
Authors: RIGAL SASTOURNE JC , MULLOT H , MULLOT JU , SGARIOTO A , HUART B , GENTES P
Published: September 2008

Purpose Intracameral cefuroxime use is an increasing practice to prevent post‐operative bacterial endophthalmitis following cataract surgery. First objective is to test stability of cefuroxime solution up to seven days at +4 °C in normal saline solution (NSS). Second objective is to evaluate if cefuroxime may be stable when prepared and stored in a less described solvent: balanced salt solution (BSS).

Methods 0.4 mL syringes containing cefuroxime solution at 10 mg per mL are prepared in a laminar air flow by pharmacists. One set of 18 syringes is prepared with NSS, another set is prepared with BSS and stored in the same conditions (+ 4°C). Three syringes of each solvent are randomly selected every day after preparation (day 1) and tested for their cefuroxime content on day 1, 2, 3, 4, 5, 7. Cefuroxime content is measured by high performance liquid chromatography coupled with UV detection without any modification prior to injection.

Results In NSS a concentration of 9.1 mg/mL [8.8 – 9.4] is measured on day 7, that is statistically different from the concentration of 9.9 mg/mL [9.4 – 10.4] measured on day 1. In BSS a concentration of 10.4 mg/mL [10.2 – 10.7] is measured on day 7, that is statistically not different from the concentration of 10.6 mg/mL [10.4 – 10.8] measured on day 1.

Conclusion The decrease of cefuroxime concentration observed in NSS is not a subject of major concern due to its limited intensity (< 10%). Moreover, syringes are currently used before day 7 in practice. The good physico‐chemical stability observed in BSS is promising but should be confirmed by microbiological tests.
Flicker induced vasodilatation is reduced in chronic smokers
Authors: LASTA M , PEMP B , WEIGERT G , SACU S , SCHMETTERER L , GARHOFER G
Published: September 2008

Purpose Habitual smoking is a risk factor for a couple of vascular diseases, including ocular pathologies such as diabetic retinopathy or age‐related macular degeneration. In the current study, we set out to investigate whether the regulation of retinal vascular tone is impaired in habitual smokers. For this purpose, vascular reactivity was tested using flicker light induced vasodilatation in smokers and in a non smoking control group.

Methods In this prospective, balanced, parallel group study, 24 chronic smokers (smoking at least 1 pack year) and 24 age and sex matched never‐smoking volunteers were included. Flicker induced vasodilatation was determined using the Dynamic Retinal Vessel Analyser. Flicker light induced vasodilatation was expressed by percent change of baseline. Intraocular pressure was determined using applanation tonometry.

Results Intraocular pressure and mean arterial pressure were comparable in both groups. Stimulation with flicker light increased retinal venous diameter by +7.6+‐ 3.3 in non‐smoking subjects. The flicker induced vasodilatation, however, was significantly diminished in chronic smokers (+4.9+‐ 2.4; p<0.05). Flicker stimulation did not affect mean arterial pressure or intraocular pressure.

Conclusion Our data clearly indicate that flicker response is reduced in chronic smokers compared to age matched healthy volunteers. This supports the hypothesis that chronic smoking leads to endothelial dysfunction in the eye.
Electroretinography and macular edema in diabetic retinopathy
Authors: SHAMSHINOVA AM , ARAKELYAN MA , MANSURINA NB , KARLOVA IZ
Published: September 2008

Purpose To examine the electrophysiological symptoms in patients with preproliferative and proliferative diabetic retinopathy (PPDR, PDR) with macular edema (ME).

Methods 24 patients with type II diabetes were investigated. OCT presented a focal, diffuse and clinically significant ME. ISCEV standard ERG methods, as well as chromatic macular and multifocal ERG (mf ERG), long‐duration flash ERG, pattern ERG (PERG) and retinocortical time (RTT) were performed.

Results ERG changes were similar in PPDR and PDR with ME. Full‐field and flicker ERG were normal or subnormal depending on the localization of the pathological process in retina. The amplitude and interpeak latency of OPs were significantly changed. A different amplitude reduction of macular chromatic ERG to red, green and blue stimuli and prolonged b‐wave latency to green and blue stimuli were revealed. The retinal density of bioelectrical activity and amplitudes of N1, P1 components were decreased. A long‐duration flash ERG showed normal or subnormal ON‐response and diminished OFF‐response. The pathological macular and mf ERG were attended by pathological full‐field and flicker ERG in certain cases. N95 component oPERG was changed in amplitude and implicit time. The RTT was prolonged in most of the patients.

Conclusion The ERG signs point to extent inclusion in pathological process of different retinal structures and layers. PERG and RTT changes indicate initial functional damage of the optic nerve. It is necessary to compare OCT and ERG data for understanding of mechanisms of visual disturbance in DR. The number of cases in which clinical and functional signs did not correspond to each other must be a subject to deep analysis before choosing a medical or laser treatment.
The role of mycophenolate mofetil in uveitis therapy
Authors: NERI P
Published: September 2008

Purpose To summarize current evidences for mycophenolate mofetil (MMF) therapies in the treatment of uveitis. The review emphasizes the safety and efficacy of MMF in the treatment of inflammatory ocular diseases.

Methods The review describes published research since early nineties, and reports the experience of a tertiary‐referral center.

Results Studies in other disciplines have proven the efficacy of MMF with a long‐lasting remission in patients affected by Crohn’s disease, severe atopic dermatitis, Wegener’s granulomatosis, rheumatoid arthritis, pemphigus vugaris, and psoriasis. Recent publications have confirmed the satisfactory control of uveitis with MMF in a large cohort of patients. Severe ocular inflammations can also have late sequela, generated by the chronic damage to the retina: cystoid macular oedema (CMO) and choroidal neovascularization (CNV) can be late occurrences. MMF has been recently used for the control of such sequela, showing a promising role in the control of both CNV and CMO.

Conclusion Non‐infectious uveitis is one of the leading causes of visual impairment in ophthalmology. Steroids can control such disease and its sequela, but a long‐term therapy with steroids could lead to complications such as high blood sugar level, osteoporosis, blood cell abnormalities, cataract and glaucoma. MMF is a reversible, non competitive, selective inhibitor of the de‐novo pathway of purine synthesis; mycophenolic acid has a strong effect to Type II isoform of inosine monophosphate dehydrogenase enzyme, providing a stronger cytostatic effect on lymphocytes than on other cells types, with minor action to Type I expressed in most other cells. The specific action of MMF on selected targets makes it a promising drug for the control of non‐infectious intraocular inflammations.
Infrared reflectance in choroidal melanoma and its correlation with fundus autofluorescence
Authors: AMSELEM L , PULIDO JS , GUNDUZ K
Published: September 2008

Purpose We have previously shown that fundus autofluorescence (FAF) improves visualization of lipofuscin (orange pigment) and subretinal fluid in pigmented choroidal melanomas in comparison with conventional fundus photography. The purpose of this study is to describe infrared reflectance (IRR) imaging findings in choroidal melanomas and compare them with those obtained by FAF imaging.

Methods Retrospective chart review of 7 consecutive patients with choroidal melanoma who underwent FAF and IRR photography. The correlation between IRR and FAF patterns and foci of orange pigment, hyperpigmentation, lipid exudates, fibrous metaplasia and subretinal fluid, was evaluated.

Results Orange pigment is hyperreflective in IRR imaging. IRR imaging highlights the presence of condensed clumps of orange pigment, presenting a good correlation with FAF imaging, but hardly detects diffuse fine lipofuscin. Hyperpigmentation is isoreflective with the normal fundus, showing low correlation with FAF, where they appear mainly hypofluorescent. Lipid exudates are hyperreflective in IRR imaging and difficult to distinguish from the orange pigment, creating a “confusion factor”. Fibrous metaplasia is mainly hyperreflective while it is hypofluorescent in FAF imaging. Subretinal fluid is hardly visible in IRR imaging, while FAF imaging highlights its presence. The top of dome‐shaped surfaces in the fundus is usually hyperreflective, creating a “noise factor” that doesn´t exist in FAF imaging.

Conclusion IRR imaging improves visualization of lipofuscin in choroidal melanomas in comparison with conventional fundus photography, but is inferior to FAF imaging.
Retinal oximetry: clinical studies
Authors: HARDARSON SH , TRAUSTASON S , GOTTFREDSDOTTIR MS , KARLSSON RA , HALLDORSSON GH , EYSTEINSSON T , BEACH JM , BENEDIKTSSON JA , STEFANSSON E
Published: September 2008

Purpose Disturbances in blood flow and oxygenation are believed to be involved in diseases such as diabetic retinopathy, retinal vascular occlusion and possibly glaucoma. The purpose of the studies presented here is to measure haemoglobin oxygen saturation (SatO2) in retinal vessels in patients with these diseases.

Methods Our retinal oximeter is based on a fundus camera, which is coupled with beam splitters and narrow band‐pass light filters. The oximeter yields fundus images with 4 wavelengths of light simultaneously. Two wavelengths, 605nm and 586nm, are used for estimation of SatO2. Measurements were made on (A) 7 patients with CRVO, (B) 19 patients before and after glaucoma surgery and (C) 21 patient with diabetic retinopathy, who were compared with 20 healthy volunteers.

Results (A) Venous SatO2 was 53±9% in CRVO eyes and 65±4% in fellow eyes (mean±SD, p=0.015, n=7). (B) Glaucoma surgery has a minimal effect on SatO2 in both arterioles (2% rise, p=0.046, n=19) and venules (no change). IOP was lowered by 13mmHg. (C) SatO2 in retinal venules was 60±8% in healthy volunteers (n=20), 67±7% in patients with non‐proliferative DR (n=12, p<0.05 compared to healthy) and 68±6% (n=9, p<0.05) in patients with proliferative DR after PRP treatment.

Conclusion Human retinal vessel oximetry can detect changes in various ocular diseases and this may help us understand the pathophysiology. The decreased venous SatO2 in CRVO is probably caused by decreased blood flow. A small change in SatO2 after glaucoma surgery may indicate a large change in oxygen delivery since blood flow may be increased with IOP lowering. Higher venous SatO2 in DR patients may for example be explained with arteriovenous shunting of blood.

Commercial interest
The pulsatile ocular blood flow (POBF) in patients with sleep apnea syndrome (SAS)
Authors: NOWAK MS , KLYSIK AB , WASZCZYKOWSKA A , GOS R , SMIGIELSKI J
Published: September 2008

Purpose To determine the correlations of pulsatile ocular blood flow (POBF) and intra ocular pressure (IOP) with sleep apnea syndrome (SAS).

Methods The study design was cross‐sectional. A total number of 26 patients, recruited into the study between January 2006 and February 2008, who underwent polysomnography were selected for the study. All of them were of European Caucasian Origin. The study participants were contacted by telephone and scheduled for eye examination. Sleep apnea syndrome was diagnosed if the apnea‐hypopnoea index (AHI) was > 5, based on whole night polysomnographic recordings. Patients with sleep apnea syndrome using CPAP were excluded from the study. Each patient underwent a slit lamp and indirect ophthalmoscope evaluation of anterior and posterior segment as well as pulsatile ocular blood flow (POBF) examination. POBF was recorded in sitting position after instillation of one drop of Alcaine. In this study, only average POBF and IOP were included for the analyses.

Results Of them, 17 (65.4%) patients had sleep apnea syndrome (SAS) and 9 (34.6%) patients were healthy and served as the control group. The study revealed that the differences between rates of average POBF and IOP measurements in the SAS group and in the control group were not statistically significant either in the right or in the left eyes (p> 0.05)

Conclusion Although, experimental studies showed that POBF was lowered in hypoxia, in our patients there was no correlation between pulsatile ocular blood flow and sleep apnea syndrome. Further investigations, concerning vascular impairment, are needed to give evidence of the mechanism of the optic nerve damage in the SAS.
Purkinje based IOL centration
Authors: TASSIGNON MJ
Published: September 2008

Purpose Surgeon‐controlled centration of IOLs might be an issue when introducing IOL optics yielding additional properties aiming at correcting spherical aberrations, astigmatism and accommodation or pseudoaccommodation.

Methods First and third Purkinje reflexes can be used during cataract surgery for the purpose of IOL alignment provided the IOL allows that freedom of action. The bag‐in‐the‐lens (BIL) concept has been designed to add this dimension of freedom to the surgeon.

Results When using the Purkinje alignment method, a physiological nasally positioning of the IOL can be observed. Aberrometry shows an increased spherical aberration but no increase of other HO aberrations.

Conclusion Surgeon‐controlled centration of IOL is possible with the BIL implantation technique. This opens new perspectives for further development and alignment of the optic.

Commercial interest
Effects of antioxidants on ocular blood flow in the LPS‐induced inflammation model in humans
Authors: FUCHSJÄGER‐MAYRL G , POLSKA E , MINNICHMAYER A , WEIGERT G , RESCH H , PEMP B , LASTA M , SCHMETTERER L
Published: September 2008

Purpose We set out to investigate whether the AREDS medication is capable of normalizing retinal blood flow reactivity to systemic hyperoxia in a human lipopolysaccharide (LPS) model.

Methods The present study was a randomized double masked placebo‐controlled parallel group study in 21 healthy volunteers. The infusion of LPS was used as a standardized experimental model of systemic inflammation associated with enhanced oxidative stress and widespread endothelial dysfunction in humans. Ocular hemodynamic measurements were performed before endotoxemia and 4 hours after the subjects had received an LPS bolus. At each of these time points the retinal vascular reactivity to hyperoxia was studied. After the first trial day the subjects had to take either the AREDS medication (n=14) or a placebo (n=7) for 14 days. Thereafter a second trial day was performed on which the time schedule exactly followed the first day as described above.

Results As expected LPS induced retinal vasodilatation (p < 0.01) together with an increase in retinal leukocyte density, which occurred because to systemic leukocytosis. The oxygen induced decrease in retinal blood flow was reduced after infusion of LPS (p < 0.01). This effect was partially restored after intake of the AREDS medication, but not after intake of placebo (p = 0.04) between groups.

Conclusion Our findings support previous data showing that LPS induces impaired endothelial function. This effect was significantly reduced by the AREDS medication. Our model may be used to study the effects of various antioxidants and the components of the AREDS medication on oxidative stress‐induced vascular dysregulation in the human retina.
The accessibility and interconnectivity of the tubular system network in toad skeletal muscle
Authors: Edwards Joshua N. , Launikonis Bradley S.
Published: September 2008

The tubular (t) system is essential for normal function of skeletal muscle fibre, acting as a conduit for molecules and ions within the cell. However, t system accessibility and interconnectivity have been mainly assessed in fixed cells where the t system no longer fully represents that of the living cell. Here, fluorescent dyes of different diameter were allowed to equilibrate within the t system of intact fibres from toad, mechanically skinned to trap the dyes, and then imaged using confocal microscopy to investigate t system accessibility and interconnectivity. Dual imaging of rhod‐2 and a 500 kDa fluorescein dextran identified regions throughout the t system that differed in the accessibility to molecules of different molecular weight. Restrictions within the t system lumen occurred at the junctions of the longitudinal and transverse tubules and also where a transverse tubule split into two tubules to maintain their alignment with Z‐lines of adjacent mis‐registered sarcomeres. Thus, three types of tubule, transverse, longitudinal and Z, can be identified by their lumenal diameter in this network. The latter we define for the first time as a tubule with a narrow lumen that is responsible for the change in register. Stretch‐induced t system vacuolation showed exclusive access of rhod‐2 to these structures indicating their origin was the longitudinal tubules. Exposing the sealed t system to highly hypertonic solution reversed vacuolation of longitudinal tubules and also revealed that these tubules are not collapsible. Fluorescence recovery after photobleaching (FRAP) measurements of t system‐trapped fluo‐5 N showed interconnectivity through the t system along the axis of the fibre. However, diffusion occurred at a rate slower than expected given the known number of longitudinal tubules linking adjacent transverse tubules. This could be explained by the observed narrow opening to the longitudinal tubules from transverse tubules, reducing the effective cross‐sectional area in which molecules could move within the t system.
Tonic activation of group I mGluRs modulates inhibitory synaptic strength by regulating KCC2 activity
Authors: Banke Tue G. , Gegelashvili Georgi
Published: September 2008

The furosemide‐sensitive potassium–chloride cotransporter (KCC2) plays an important role in establishing the intracellular chloride concentration in many neurons within the central nervous system. Consequently, modulation of KCC2 function will regulate the reversal potential for synaptic GABAergic inputs, thus setting the strength of inhibitory transmission. We show that tonic activation of group I metabotropic glutamate receptors (mGluR1s) regulates inhibitory synaptic strength via modulation of KCC2 function in pyramidal neurons of the hippocampal CA3 area. Specifically, group I mGluRs signal via activation of a protein kinase C‐dependent pathway to alter KCC2 activity, thereby altering the intracellular chloride concentration, and thus inhibitory synaptic input. This interaction between the glutamatergic and chloride transport systems highlights a novel homeostatic mechanism whereby ambient glutamate levels directly regulate the inhibitory synaptic tone by setting the activity level of KCC2. Thus, mGluRs are poised to play a pivotal role in providing a direct interplay between the excitatory and inhibitory systems in the hippocampus.
Myocardial blood flow and adenosine A2Areceptor density in endurance athletes and untrained men
Authors: Heinonen Ilkka , Nesterov Sergey V. , Liukko Kaisa , Kemppainen Jukka , Någren Kjell , Luotolahti Matti , Virsu Pauliina , Oikonen Vesa , Nuutila Pirjo , Kujala Urho M. , Kainulainen Heikki , Boushel Robert , Knuuti Juhani , Kalliokoski Kari K.
Published: September 2008

Previous human studies have shown divergent results concerning the effects of exercise training on myocardial blood flow (MBF) at rest or during adenosine‐induced hyperaemia in humans. We studied whether these responses are related to alterations in adenosine A2Areceptor (A2AR) density in the left‐ventricular (LV) myocardium, size and work output of the athlete's heart, or to fitness level. MBF at baseline and during intravenous adenosine infusion, and A2AR density at baseline were measured using positron emission tomography, and by a novel A2AR tracer in 10 healthy male endurance athletes (ET) and 10 healthy untrained (UT) men. Structural LV parameters were measured with echocardiography. LV mass index was 71% higher in ET than UT (193 ± 18 g m−2versus114 ± 13 g m−2, respectively). MBF per gram of tissue was significantly lower in the ET than UT at baseline, but this was only partly explained by reduced LV work load since MBF corrected for LV work was higher in ET than UT, as well as total MBF. The MBF during adenosine‐induced hyperaemia was reduced in ET compared to UT, and the fitter the athlete was, the lower was adenosine‐induced MBF. A2AR density was not different between the groups and was not coupled to resting or adenosine‐mediated MBF. The novel findings of the present study show that the adaptations in the heart of highly trained endurance athletes lead to relative myocardial ‘overperfusion’ at rest. On the other hand hyperaemic perfusion is reduced, but is not explained by A2AR density.
Acting locally but sensing globally: impact of GABAergic synaptic plasticity on phasic and tonic inhibition in the thalamus
Authors: Bright Damian P. , Brickley Stephen G.
Published: September 2008

We have discovered that adult thalamocortical relay neurones exhibit a sustained enhancement of synaptic inhibition triggered by transient action potential firing of a single thalamic relay neurone. The sustained activity‐dependent increase in IPSC frequency (+48.3 ± 11.4%, n= 32) was blocked by chelating calcium inside an individual cell, by scavenging nitric oxide or by blocking NMDA receptor activation in the thalamus. Surprisingly, the tonic inhibition that is known to result from extrasynaptic GABAA receptor activation in these cells was unaffected by this local form of plasticity. However, tonic inhibition was increased (+131.9 ± 56.5%, n= 13) following widespread changes in GABA release across the thalamus. These data suggest that thalamocortical sleep‐state oscillations requiring membrane hyperpolarization will be influenced by global sensing of GABA release acting through extrasynaptic GABAA receptors. In contrast, local changes in GABA release of the type observed following this novel form of activity‐dependent plasticity will influence local integration of sensory information without changing levels of tonic inhibition.
The differential expression of low‐threshold K+currents generates distinct firing patterns in different subtypes of adult mouse trigeminal ganglion neurones
Authors: Catacuzzeno Luigi , Fioretti Bernard , Pietrobon Daniela , Franciolini Fabio
Published: September 2008

In adult mouse trigeminal ganglion (TG) neurones we identified three neuronal subpopulations, defined in terms of their firing response to protracted depolarizations, namely MF neurones, characterized by a multiple tonic firing; DMF neurones, characterized by a delay before the beginning of repetitive firing; and SS neurones, characterized by a strongly adapting response. The three subpopulations also differed in several other properties important for defining their functional rolein vivo, namely soma size, action potential (AP) shape and capsaicin sensitivity. MF neurones had small soma, markedly long AP and mostly responded to capsaicin, properties typical of a subgroup of C‐type nociceptors. SS neurones had large soma, short AP duration and were mostly capsaicin insensitive, suggesting that most of them have functions other than nociception. DMF neurones were all capsaicin insensitive, had a small soma size and intermediate AP duration, making them functionally distinct from both MF and SS neurones. We investigated the ionic basis underlying the delay to the generation of the first AP of DMF neurones, and the strong adaptation of SS neurones. We found that the expression of a fast‐inactivating, 4‐AP‐ and CP‐339,818‐sensitive K+current (IA) in DMF neurones plays a critical role in the generation of the delay, whereas a DTX‐sensitive K+current (IDTX) selectively expressed in SS neurones appeared to be determinant for their strong firing adaptation. A minimal theoretical model of TG neuronal excitability confirmed thatIAandIDTXhave properties congruent with their suggested role.
Development of a Transparent Heater to Measure Surface Temperature Fluctuations Under Spray Cooling Conditions
Authors: Griffin A. R. , Vijayakumar A. , Chen R.-H. , Sundaram K. B. , Chow L. C.
Published: September 2008

A heater designed to monitor surface temperature fluctuations during pool boiling and spray cooling experiments while the bubbles are simultaneously being observed has been fabricated and tested. The heat source was a transparent indium tin oxide (ITO) layer commercially deposited on a fused quartz substrate. Four copper-nickel thin film thermocouples (TFTCs) on the heater surface measured the surface temperature, while a thin layer of sapphire or synthetic fused silica provided electrical insulation between the TFTCs and the ITO. The TFTCs were microfabricated using the lift-off process to deposit the nickel and copper metal films. The TFTC elements were 50μm wide and overlapped to form a 25×25μm2 junction. A DAQ program recorded the TFTC voltages at a sampling rate of 50kHz and sent a trigger to a high-speed camera to synchronize bubble images with the surface temperature data. As the bubbles and their contact rings grew over the TFTC junction, correlations between bubble behavior and surface temperature changes were demonstrated.
Ground Heat Transfer From a Varying Line Source With Seasonal Temperature Fluctuations
Authors: Duan X. , Naterer G. F.
Published: September 2008

In this paper, transient heat conduction between a line heat source and a semi-infinite medium (representing a foundation of a power transmission tower and the surrounding ground) is analyzed numerically and experimentally. The tower foundation is represented by a metal rod buried in a semi-infinite medium. Using an experimental test cell with a data acquisition system, heat transfer and temperature measurements within the domain are collected. The experimental studies are first applied to unidirectional heat conduction, wherein the analytical solutions are compared against measured temperature responses. Then two transient heat transfer cases are studied: one case with a steady heat input provided by an electrical heater and another with sinusoidal temperature variations achieved by temperature-controlled fluid in a heat exchanger. The analysis shows that a metal tower footing has significant thermal effects on the temperature response of the local half-space around the footing in the foundation. This thermal effect varies with time, as well as spatially at different positions around the tower footing. In particular, measured results from the case of sinusoidal temperature variations show that the tower footing introduces additional temperature increases in the “summer” periods and temperature decreases in the “winter” periods.
Benchmark Studies for the Generalized Streamwise Periodic Heat Transfer Problem
Authors: Beale Steven B.
Published: September 2008

This is a comparison of calculations performed with a scheme for handling streamwise-periodic boundary conditions with known solutions to the common problem of fully developed heat transfer in a plane duct. Constant value, constant flux, mixed boundary conditions, and linear wall flux (conjugate heat transfer) are all considered. Agreement is, in every case, near exact showing that the methodology may be applied with confidence to complex engineering problems with a variety of thermal wall boundary conditions.
Stability and Convection in Impulsively Heated Porous Layers
Authors: Kohl M. J. , Kristoffersen M. , Kulacki F. A.
Published: September 2008

Experiments are reported on initial instability, turbulence, and overall heat transfer in a porous medium heated from below. The porous medium comprises either water or a water-glycerin solution and randomly stacked glass spheres in an insulated cylinder of height:diameter ratio of 1.9. Heating is with a constant flux lower surface and a constant temperature upper surface, and the stability criterion is determined for a step heat input. The critical Rayleigh number for the onset of convection is obtained in terms of a length scale normalized to the thermal penetration depth as Rac=83/(1.08η−0.08η2) for 0.02<η<0.18. Steady convection in terms of the Nusselt and Rayleigh numbers is Nu=0.047Ra0.91Pr0.11(μ/μ0)0.72 for 100<Ra<5000. Time-averaged temperatures suggest the existence of a unicellular axisymmetric flow dominated by upflow over the central region of the heated surface. When turbulence is present, the magnitude and frequency of temperature fluctuations increase weakly with increasing Rayleigh number. Analysis of temperature fluctuations in the fluid provides an estimate of the speed of the upward moving thermals, which decreases with distance from the heated surface.
The Thickness of the Liquid Microlayer Between a Sliding Bubble and a Heated Wall: Comparison of Models to Experimental Data
Authors: Hollingsworth D. Keith , Li Xin , Witte Larry C.
Published: September 2008

Sliding vapor bubbles are known to create high heat transfer coefficients along the surfaces against which they slide. The details of this process remain unclear and depend, in part, on the evolution of the liquid microlayer that forms between the bubble and the surface, as the bubble grows by evaporation. A mechanistic model of the microlayer thickness verified by direct observation of the microlayer thickness is needed. This paper describes a comparison of measurements from a recent set of experiments to the results of microlayer models from literature and to the predictions of a new model presented here for the first time. The measurements were produced by a laser-based method developed to measure the thickness of the liquid microlayer between a cap-shaped sliding bubble and an inclined heated wall. Microlayer thicknesses of 22–55 μm were obtained for saturated FC-87 and a uniform-temperature surface inclined at 2–15 deg from the horizontal. The basis of each model, input requirements, limitations, and performance relative to this data set is discussed. A correlation is developed based on the structure of the lubrication theory. It collects the measured microlayer thickness presented as a microlayer Reynolds number to within ±10%. This correlation depends only on bubble volume, inclination, and a bubble shape factor, all of which can be determined experimentally to within reasonable accuracy.
Adiabatic Horizontal and Vertical Pressure Drop of Carbon Dioxide Inside Smooth and Microfin Tubes at Low Temperatures
Authors: Kim Yoon Jo , Jang Jeremy , Hrnjak Predrag S. , Kim Min Soo
Published: September 2008

This paper presents the pressure drop data and the analysis of adiabatic CO2 flow in horizontal and vertical smooth and microfin tubes at saturation temperatures around −20°C. The test tubes had 3.48mm inner diameter smooth tube and a 3.51mm melt-down diameter microfin tube. The test was performed over a mass flux range of 200–800kg∕m2s and at saturation temperatures of −25°C and −15°C. The effects of various parameters—mass flux, saturated temperature, and tube diameter—on pressure drop were qualitatively analyzed. The analyses showed that the frictional pressure drop characteristics of vertical two-phase flow were much different from that of the horizontal two-phase flow. The microfin tube can be considered as “very rough tube” having the roughness of “fin height.” The data were compared with several correlations. The existing frictional pressure drop correlation is sufficient to predict the horizontal pressure drop in smooth tube. For the vertical pressure drop, the simple combination of the frictional pressure drop and void fraction model was in comparatively good agreement. However, the qualitative results showed that there were some limits to cover the different mechanisms related to the interfacial shear stress. The average enhancement factors and penalty factors evidenced that it was not always true that the internally finned geometry guaranteed the superior in-tube condensation performance of microfin tube in refrigeration system and air-conditioning systems.
Prediction of Thermal Emission and Exchange Among Neighboring Wavelength-Sized Spheres
Authors: Mackowski Daniel W. , Mishchenko Michael I.
Published: September 2008

An analysis of radiative emission and radiative exchange among an ensemble of closely spaced, wavelength-sized spheres, in which each sphere in the ensemble is at a distinct and uniform temperature, is presented. We show that the rate of spectral emission from a specific sphere in the ensemble and the rate at which emission is exchanged between a pair of spheres can be deduced from the application of reciprocity and energy conservation principles to the solution of Maxwell’s time harmonic wave equations for a sphere ensemble that is exposed to a plane wave incident field of wavelength λ. We show that in the limit of d∕λ→0, the emissive exchange between a pair of spheres becomes inversely proportional to the gap thickness d. We also show that when the spheres are in the mutual far-field zones of each other, the emissive exchange between the spheres can be well approximated by geometric configuration factors, with an effective area correction to account for finite wavelength effects.
Anticontrol of Chaos Reduces Spectral Emissions
Authors: Morel Cristina , Vlad Radu , Morel Jean-Yves
Published: September 2008

Switch-mode power supplies usually emit electromagnetic interferences at the switching frequency and its harmonics. Inducing chaos in these systems has recently been suggested as a means of reducing these spectral emissions, yet at the expense of aggravating the overall magnitude of the ripple in the output voltage. We propose here a new nonlinear feedback, which induces chaos and which is able at the same time to achieve a low spectral emission and to maintain a small ripple in the output. The design of this new and simple controller is based on the propriety that chaotified nonlinear systems present many independent chaotic attractors of small dimensions.
Optimization of a Platform With Respect to Force Contact Conditions
Authors: Bestle Dieter
Published: September 2008

Chimneys in operating power plants cannot be demolished in the classical way by dynamite. A new technology has been invented where they are cut off starting from the top and where the pieces of the reinforced concrete chimney are dropped through the inner pipe of the chimney. In order to avoid the falling down of pieces on the outer side, a ring platform is attached to the chimney by pure force contact, which allows semi-automatic climbing up and down. The paper addresses two crucial design decisions concerning the ring platform: the design of the contact geometry and the shape of the ring structure. Both design problems are formulated as multicriterion optimization problems where the first one can be solved partially in an analytical way whereas the second one has to be solved numerically. It will be shown how the problems can be formulated in various ways depending on the technical requirements.