Quantitative vitreous fluorophotometry applying a mathematical model of the

A slit-lamp fluorophotometric method is presented that permits calculation of a blood-retinal barrier permeability to fluorescein (P) and a diffusion coefficient for fluorescein in the vitreous body (D). The calculations are performed by relating the time course of the free-not protein bound-fluorescein concentration in the bloodstream with the fluorescein concentration profile in the vitreous body. The combination is performed automatically on a computer by applying a simplified mathematical model of the eye. P refers to the area of the barrier of the model eye. In a group of six normal persons, the mean P was (1.1 ± 0.4) X 10~7 cm/sec (mean ± SD), while in six diabetic patients with background retinopathy and macular edema the mean P was (7.1 ± 3.8) X 10~7 cm/sec. The mean I) was (7.4 ± 3.4) X 10~6 cm 2 /sec in the normal group and (9.6 ± 2.0) X 1O~6 cm 2 /sec in diabetic patients, corresponding as a first approximation to free diffusion in water. Model calculations show that knowing the fluorescein concentration in the bloodstream is considerably significant for the calculation of the permeability, contributing factors up to 50%. For the low-permeation situation, subtraction of the preinjection scan contributes a factor of 50% for both permeability and diffusion coefficient. The exact placement in the vitreous body of the concentration profile, by applying a formalism that transforms slit-lamp movement to intraocular distance, contributes a factor of 20% on the diffusion coefficient. The permeability obtained with the model can be calculated as the ratio between area of vitreous and plasma fluorescein concentration curves within 20%. Active transport of fluorescein across the blood-retinal barrier in the direction of vitreous to blood does not seem to be significant within the first 2 hr after fluorescein injection. Invest Ophthalmol Vis Sci 26: [698][699][700][701][702][703][704][705][706][707][708][709][710] 1985 During the last 8 years, vitreous fluorophotometry has been used to quantitate the permeability properties of the blood-retinal barrier to fluorescein. The method, originally introduced by Cunha-Vaz and co-workers, 12 has been based upon intravenous (IV) injection of a standard dose of fluorescein, which usually after 60 min was followed by a slit-lamp photometric determination of the fluorescein concentration in the vitreous body. The magnitude of the concentration in the posterior part of the vitreous body has been used as a measurement of the barrier permeability. However, as it has been pointed out, it is important to incorporate the fluorescein concentration in the plasma in the calculation of the perme- ability of the barrier 3 " 13 and to include more than the concentration of fluorescein in a single point of the vitreous body in the calculations. An analysis of the fluorescein concentration profile in the vitreous body can, furthermore, provide qualitative information of the diffusion properties in the vitreous body. 14 Quantitative evaluation of this factor has previously been reported for the anterior vitreous 3 and recently for the posterior part of the vitreous body, based upon first principles. 13 The present article presents a more complete method for the calculation of a blood-retinal barrier permeability to fluorescein and a diffusion coefficient for fluorescein in the posterior part of the vitreous body. The method is based upon simultaneous determinations of the fluorescein concentration in plasma and in vitreous body. These data are combined on a computer by applying a simplified mathematical model of the eye to give a fluorescein permeability of the barrier and a diffusion coefficient for fluorescein in the vitreous body. The method, which is based on a series of studies of 165 human examinations, is presented here in detail. The individual clinical studies will be presented elsewhere in separate articles. The mathematical model has been described previously, Materials and Methods Fluorophotometric Equipment Slit lamp: The slit lamp is a Rodenstock 2001 mounted with oculars (700-10 Gamma Scientific; San Diego, CA) which in their focal point contain a 450 jum fiber optic probe picking up light from the slitlamp focal plane as described by Cunha-Vaz 1 and by Krogsaa et al. 17 In the focal plane, the slit is 1 mm high and 0.1 mm wide. The angle between slit and symmetry axis of the biomicroscope is 11.4° and the angle between symmetry axis and ocular is 5.6°. The light source of the slit lamp is a 450 W zenon arc lamp connected with the slit lamp by a fiber optic cable. This cable is interrupted by a light chopper (Rofin 7500; Rofin, England), which chops the light with a frequency of 432 Hz. The intensity of the blue light in the slit is 5 mW/cm 2 , as determined by a fluxmeter (Hewlett Packard type 8330 A). The filters used are a blue (SWP 495) and yellow (LWP 515) interference filter (Optical Laboratory; Lyngby, Denmark), with transmission characteristics as shown in Amplification and registration equipment: The light from the optic probe in the ocular is passed to a photomultiplier (initially a Gamma Scientific Model D-46 but now a PR-1400 RF, Products for Research Inc.; Danvers, MA) operated at room conditions. The photomultiplier is directly connected with an amplifier triggered from the chopper (Lock-in, Model 128 A, Princeton Applied Research; Princeton, NJ). This system increases the sensitivity of the equipment by a factor of seven. The lock-in amplifier is connected to the Y-axis of a X-Y recorder (Philips PM 8041; Eindhoben, Netherlands). The sagittal movement of the slit lamp is transduced to the X-axis of the recorder by a precision potentiometer. A mechanical device connected to the potentiometer secures that the movement of the slit lamp occurs in the sagittal plane. A foot switch allows an indication to be made on the X-axis in all desired positions of the slit-lamp focal plane and thereby also the ocular fiber optic probe in relation to the ocular structures, which are in focus when the focal plane is moved from retina to cornea. The X-Y recorder is coupled in parallel to a microcomputer Sensitivity and spatial resolution of the equipment: The sensitivity of the equipment defined as the concentration required to yield a signal twice as high as the background noise was 2.5 X 10~9 g/ml. A crosssection of the volume of measurement-the optical diamond 1819 -is constituted by a parellelogram measuring (0.48 X 2.16) mm with a diagonal of 2.64 mm. The spatial resolution was tested in a double compartment cuvette Although the optical diamond, as calculated from an analysis of the optics of the slit-lamp equipment, has the same geometry in these in vitro experiments The Fluorophotometric Examination Fluorescein administration and analysis in blood: Flourescein (14 mg/kg body weight) was injected in an antecubital vein over a 60-sec period. From a cannula in an antecubital vein in the other arm, blood samples were obtained before, and 5, 15, 30, 60, and 120 min after injection. After centrifugation plasma was analyzed for total as well as free (not protein-bound) fluorescein concentration, the latter by ultrafiltration, as described in detail elsewhere. 6 ' 7 Briefly, the analysis is performed in the following way: Blood is collected in heparinized test tubes. After centrifugation plasma is ultrafiltrated using the Amicon MPS-1 system (Amicon Corporation; Danvers, MA). Initially, Millipore Ultra Free disposable filters were used, giving the same results as the Amicon filters. The total fluorescein concentration is determined after sufficient dilution of plasma. As a control of the method and an estimation of the free fluorescein concentration in the bolus during its first passage through the ocular circulation, fluorescein is added to plasma samples obtained before injection of fluorescein; these samples were analyzed in the same way as the other plasma samples. The concentration of total fluorescein in these test samples is 5 X 10~6 g/ml, 5 X 10~5 g/ml, and 3 X 10" 4 g/ml, the latter corresponding to the assumed concentration in the bolus. The free fraction constitutes approximately 15% for all the concentration ranges. The bolus concentration: The concentration of fluorescein in the ocular arterial, capillary, and venous system during the fluorescein injection is unknown (the bolus concentration), but it can be estimated according to the following reasoning. The fluorescein solution (1 X 10" 1 g/ml) is injected over a 1-min period. It is assumed that the cardiac output is 5 1/min; hematocrit, 43%; and recirculation and extraction in pulmonary circulation is neglected. A person of 70 kg will receive 9.8 ml fluorescein over the 1-min period, and the total plasma fluorescein concentration in the bolus will accordingly be 10"' X 9.8 5000 X 0.57 = 3.4 X 10~4g/ml. Assuming an unbound fluorescein concentration of 15% at this concentration, 7 the concentration in the bolus during the 1 min of injection will be 5 X 10" 5 g/ml. Fluorophotometry: The present article is based on experience obtained over a 3-year period in which 165 examinations were performed. Two typical examinations, one with low leakage (normal person) and one with high leakage (diabetic patient), are shown in the article. The examination is performed after the eye is anaesthetized with oxybuprocaine (0.4%) and the pupil dilated with metaoxidrin (10%) and 0.5% tropicamide. A Goldmann contact lens (Haag-Streit AG; Liebefeld, Switzerland) with specifications given elsewhere 17 is used. An axial fluores- 701 cence scan is made before injection of fluorescein and 30, 60, and 120 min after injection. The scan is obtained in the following way: First the macula is focused. The slit lamp and its focal plane is then moved manually toward the examiner through the vitreous body, the lens, and the anterior chamber with a speed of less than 2 mm/sec, which secures that the amplification system, which operates with a time constant of 0.3 sec, is able to follow the slitlamp movement. A time constant of 0.1 sec gave the same results. However, the noise was then too high for the low-permeation situation, and 0.3 sec was chosen for all measurements. A feedback system signals if the speed is higher than 2 mm/sec. Informed consent was obtained from the persons examined after the nature of the procedures had been explained fully. Calculation of a Blood-Retinal Barrier Permeability and a Diffusion Coefficient in the Vitreous Body The calculation of permeability (P) and diffusion coefficient (D) is performed by linking the concentration course of free fluorescein in the plasma with the concentration profile in the vitreous body. This linkage is performed by the application of a simplified model of the eye. The model that will be described in more detail below is coupled on a large computer (see Larsen et al 10 ). However, before transmission of data to the large computer, three procedures are performed on the small computer (SPC/1), where data are collected on line: (1) the X-axis is transformed to real intraocular distances; (2) the fluorescence signal obtained before injection is subtracted from the signal obtained after injection; and (3) the amount of data is reduced. Transformation of the X-axis to intraocular distance: The movement of the slit lamp is, as mentioned, transduced to the X-axis by a potentiometer. By knowing the amplification of recorder and potentiometer, a movement on the X-axis can be transformed to movement of the slit lamp. The slit lamp movement, however, cannot be transformed directly to intraocular distances. Due to the refraction of light in the compound optical system, the movement of the slit-lamp focal plane is different from the movement of the slit lamp itself. 151718 -20 With the knowledge of the ratio between the two movements, the X-axis movement of the pen on the recorder can be transformed to intraocular distances according to the equation: where X e is intraocular distance; X r , distance on recorder; F, the ratio (movement of focal plane in the eye/movement of slit lamp); and M, the amplification of recorder and potentiometer, which in the present set up is 1:12.1. As shown by Krogsaa et al. Correction for preinjection value: The autofluorescence signal, which is obtained before injection of fluorescein, is converted to intraocular fluorescence signal by the same procedure as described above. The ordinate value of corresponding intraocular positions of the preinjection curve is subtracted automatically from the actual concentration profile obtained. MOVEMENT OF SLIT LAMP (0.5 mm step) 17 F is calculated for every 0.5-mm movement of the slit lamp. It appears that F is different for the three segments of the eye (anterior chamber, lens, and vitreous body) and varies within the individual compartments. marker point 2 to the center of the eye are transmitted to the computer and used for further analysis. Together with the transmission of the concentration profile, the time course of the free fluorescein concentration in the plasma is also transmitted to the central computer. The Simplified Model of the Eye and its Mathematical Formalism The simplified model: In order to calculate a permeability of the blood-retinal barrier and a diffusion coefficient in the vitreous body a simplified model of the eye was developed, as schematically shown in The mathematical formalism: The formulation of the mathematical formalism and the solution of the equations which describe the combination of the model parameters are given in detail elsewhere. where c m (rj, t) is the measured value at r = r is and c is the corresponding value given by equation (2). Equatio

A multi-objective optimization approach in defining the decarbonization strategy of a refinery

Nowadays, nearly one quarter of global carbon dioxide emissions are attributable to energy use in industry, making this an important target for emission reductions. The scope of this study is hence that to define a cost-optimized decarbonization strategy for an energy and carbon intensive industry using an Italian refinery as a case study. The methodology involves the coupling of EnergyPLAN with a Multi-Objective Evolutionary Algorithm (MOEA), considering the minimization of annual cost and CO2 emissions as two potentially conflicting objectives and the energy technologies’ capacities as decision variables. For the target year 2025, EnergyPLAN+MOEA has allowed to model a range of 0-100 % decarbonization solutions characterized by optimal penetration mix of 22 technologies in the electrical, thermal, hydrogen feedstock and transport demand. A set of nine scenarios, with different land use availabilities and implementable technologies, each consisting of 100 optimal systems out of 10000 simulated ones, has been evaluated. The results show, on the one hand the possibility of achieving medium-high decarbonization solutions at costs close to current ones, on the other, how the decarbonization pathways strongly depend on the available land for solar thermal, photovoltaic and wind, as well as the presence of a biomass supply chain in the region

Quantum memory for entangled two-mode squeezed states

A quantum memory for light is a key element for the realization of future quantum information networks. Requirements for a good quantum memory are (i) versatility (allowing a wide range of inputs) and (ii) true quantum coherence (preserving quantum information). Here we demonstrate such a quantum memory for states possessing Einstein-Podolsky-Rosen (EPR) entanglement. These multi-photon states are two-mode squeezed by 6.0 dB with a variable orientation of squeezing and displaced by a few vacuum units. This range encompasses typical input alphabets for a continuous variable quantum information protocol. The memory consists of two cells, one for each mode, filled with cesium atoms at room temperature with a memory time of about 1msec. The preservation of quantum coherence is rigorously proven by showing that the experimental memory fidelity 0.52(2) significantly exceeds the benchmark of 0.45 for the best possible classical memory for a range of displacements.Comment: main text 5 pages, supplementary information 3 page

T-Cell Memory Responses Elicited by Yellow Fever Vaccine are Targeted to Overlapping Epitopes Containing Multiple HLA-I and -II Binding Motifs

The yellow fever vaccines (YF-17D-204 and 17DD) are considered to be among the safest vaccines and the presence of neutralizing antibodies is correlated with protection, although other immune effector mechanisms are known to be involved. T-cell responses are known to play an important role modulating antibody production and the killing of infected cells. However, little is known about the repertoire of T-cell responses elicited by the YF-17DD vaccine in humans. In this report, a library of 653 partially overlapping 15-mer peptides covering the envelope (Env) and nonstructural (NS) proteins 1 to 5 of the vaccine was utilized to perform a comprehensive analysis of the virus-specific CD4+ and CD8+ T-cell responses. The T-cell responses were screened ex-vivo by IFN-γ ELISPOT assays using blood samples from 220 YF-17DD vaccinees collected two months to four years after immunization. Each peptide was tested in 75 to 208 separate individuals of the cohort. The screening identified sixteen immunodominant antigens that elicited activation of circulating memory T-cells in 10% to 33% of the individuals. Biochemical in-vitro binding assays and immunogenetic and immunogenicity studies indicated that each of the sixteen immunogenic 15-mer peptides contained two or more partially overlapping epitopes that could bind with high affinity to molecules of different HLAs. The prevalence of the immunogenicity of a peptide in the cohort was correlated with the diversity of HLA-II alleles that they could bind. These findings suggest that overlapping of HLA binding motifs within a peptide enhances its T-cell immunogenicity and the prevalence of the response in the population. In summary, the results suggests that in addition to factors of the innate immunity, "promiscuous" T-cell antigens might contribute to the high efficacy of the yellow fever vaccines. © 2013 de Melo et al

Border Terriers under primary veterinary care in England: demography and disorders

The Border Terrier is a working terrier type that is generally considered to be a relatively healthy and hardy breed. This study aimed to characterise the demography and common disorders of Border Terriers receiving veterinary care in England using de-identified electronic patient record data within the VetCompass™ Programme

Clinical trial of laronidase in Hurler syndrome after hematopoietic cell transplantation.

BackgroundMucopolysaccharidosis I (MPS IH) is a lysosomal storage disease treated with hematopoietic cell transplantation (HCT) because it stabilizes cognitive deterioration, but is insufficient to alleviate all somatic manifestations. Intravenous laronidase improves somatic burden in attenuated MPS I. It is unknown whether laronidase can improve somatic disease following HCT in MPS IH. The objective of this study was to evaluate the effects of laronidase on somatic outcomes of patients with MPS IH previously treated with HCT.MethodsThis 2-year open-label pilot study of laronidase included ten patients (age 5-13 years) who were at least 2 years post-HCT and donor engrafted. Outcomes were assessed semi-annually and compared to historic controls.ResultsThe two youngest participants had a statistically significant improvement in growth compared to controls. Development of persistent high-titer anti-drug antibodies (ADA) was associated with poorer 6-min walk test (6MWT) performance; when patients with high ADA titers were excluded, there was a significant improvement in the 6MWT in the remaining seven patients.ConclusionsLaronidase seemed to improve growth in participants <8 years old, and 6MWT performance in participants without ADA. Given the small number of patients treated in this pilot study, additional study is needed before definitive conclusions can be made

Biphenotypic sinonasal sarcoma: European multicentre case-series and systematic literature review

Objective. Biphenotypic sinonasal sarcoma (BSNS) is a rare low-grade cancer that was included from the 4th edition of WHO classification of head and neck tumours. The purpose of this study is to analyse clinical behaviour, pattern of recurrences and survival outcomes of this neoplasm. Methods. Retrospective review of patients affected by BSNS who were treated via an en-doscopic-assisted approach in 6 European tertiary-care referral hospitals. Cases of BSNS described in literature since 2012 to date were fully reviewed, according to PRISMA guide-lines. Results. A total of 15 patients were included. Seven patients were treated via an endoscopic endonasal approach, 4 with endoscopic transnasal craniectomy, and 4 via a cranio-endoscopic approach. Adjuvant treatment was delivered in 2 cases. After a mean follow-up of 27.3 months, systemic metastasis was observed in 1 case; the 5-year overall survival and disease-free survival rates were 100% and 80 ± 17.9%, respectively. Conclusions. BSNS is a locally aggressive tumour with a low recurrence rate and encour-aging survival outcomes if properly treated with surgical resection and free margins fol-lowed by adjuvant radiotherapy for selected cases. Endoscopic-assisted surgery is safe and effective as an upfront treatment within a multidisciplinary care protocol

A Systematic Review of Music Therapy Practice and Outcomes with Acute Adult Psychiatric In-Patients

PMCID: PMC3732280This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Assessment of correlation between knee notch width index and the three-dimensional notch volume

This study was done to determine whether there is a correlation between the notch volume and the notch width index (NWI) as measured on the three most frequently used radiographic views: the Holmblad 45°, Holmblad 70°, and Rosenberg view. The notch volume of 20 cadaveric knees was measured using Computed Tomography (CT). The Holmblad 45°, Holmblad 70°, and Rosenberg notch view radiographs were digitally re-created from the CT scans for each specimen, and the NWI was measured by two observers. The Pearson correlation coefficient between the NWI and notch volume was calculated, as well as between the three views. An independent t test was performed to determine the difference in NWI and notch volume between male and female specimens. The reliability for each view was also determined. There was no correlation between the NWI as measured on the Holmblad 45°, Holmblad 70°, or Rosenberg view and the notch volume. All three radiographic views proved reliable, but showed only a moderate correlation with each other. Men had larger notch volumes than women, but there was no difference in NWI. A knee with a small intercondylar notch is often considered an increased risk for ACL rupture. The NWI is a frequently used two-dimensional method to determine notch size. However, in the present study, this index was not positively correlated with the overall volume of the notch. Based on the results of the current study, the authors would advice to use caution when using notch view radiographs in a clinical setting to predict risk of ACL rupture