Fluorescein dye-dilution technique and retinal circulation

1978 ◽  
Vol 234 (3) ◽  
pp. H315-H322 ◽  
Author(s):  
C. E. Riva ◽  
G. T. Feke ◽  
I. Ben-Sira
Keyword(s):  
Fluorescence Intensity ◽  
Time Course ◽  
Theoretical Models ◽  
Normal Function ◽  
Fluorescent Light ◽  
Circular Aperture ◽  
Excitation Light ◽  
On Line ◽  
Log Normal ◽  
Mean Time

Using theoretical models for the flow of fluourescein dye in retinal arteries and veins, we have determined the effects of optical absorption in blood of the incident excitation light and the emitted fluorescent light on the time course of measured fluorescence intensity, I(t). Our results indicate that I(t) curves recorded from arteries adequately represent the mean time course of the fluorescein concentration (C(t)), when either a circular or rectangular light-collecting aperture is used. I(t) curves recorded from veins adequately represent C(t), but only when a circular aperture of approximately the same diameter as that of the vessel is used. A two-point fluorophotometer, which provides simultaneous, on-line measurements of arterial and venous I(t) curves is described. Typical recordings obtained with the instrument are shown and the method employed to analyze the curves quantitatively is described in detail. This method, which consists of fitting the first passage of the fluorescence intensity curve with a log-normal function, provides results that are more accurate than those obtained using the standard exponential extrapolation method.

Metabolic control of Argyropelecus hemigymnus photophores: effects of glucose and pyruvate

1991 ◽  
Vol 69 (9) ◽  
pp. 2410-2413 ◽  
Author(s):  
J. Mallefet ◽  
F. Baguet
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Metabolic Control ◽  
Time Course ◽  
Light Emission ◽  
Mesopelagic Fish ◽  
Fresh Weight ◽  
Hypometabolic State ◽  
The Mean ◽  
Mean Time

Modifications in oxygen consumption and luminescence of isolated luminescent organs of the mesopelagic fish Argyropelecus hemigymnus following glucose and pyruvate administration were studied before and during light emission triggered by adrenaline. Isolated photophores (mean fresh weight 13.5 ± 0.9 mg) at rest, i.e., in the absence of light emission, in saline (20 °C) exhibit a respiration rate of 1.045 ± 0.082 (SE) nmol O2/min (n = 35). A significant decrease (p = 0.05) in oxygen consumption was observed after the addition of 5.5 mM glucose. Instead of the oxygen decrease usually observed as a result of control stimulations using adrenaline, photophores pretreated with glucose increased their oxygen uptake in response to adrenaline, and maximal light emission was reduced by 85% (p = 0.01). The addition of 5.5 mM pyruvate induced a significant transient increase (p = 0.05) in oxygen uptake of isolated photophores, though this treatment did not statistically modify the mean time course of oxygen consumption and light emission in response to adrenaline. The hypothesis of a hypometabolic state of the isolated photophores of A. hemigymnus during light emission is discussed.

Abstract P502: Abnormal Myocyte Calcium Dynamics And The Resultant Contraction Band Formation Of The Rat Heart Under Irreversible Injury By Membrane Permeabilization

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Yuma Morishita ◽  
Shoko Tamura ◽  
Kentaro Mochizuki ◽  
Yoshinori Harada ◽  
Hideo Tanaka
Keyword(s):  
Fluorescence Intensity ◽  
High Frequency ◽  
Time Course ◽  
Morphological Changes ◽  
Confocal Imaging ◽  
Band Formation ◽  
Contraction Band Necrosis ◽  
Scanning Confocal Microscopy ◽  
The Individual ◽  
Contraction Band

Ca 2+ overload is a cardinal feature of cardiomyocyte injury, and its progression to irreversible state leads to cell death. However, unknowns are the precise spatiotemporal changes in the myocyte Ca 2+ dynamics and the relevant cell morphology of irreversibly injured hearts. On the hypothesis that myocytes exhibit high-frequency Ca 2+ waves and contraction band necrosis in saponin-permeabilized injured heart, we observed changes in the Ca 2+ dynamics and the relevant morphological changes in the subepicardial myocardium of the Fluo4-loaded rat hearts (n = 14) by rapid-scanning confocal microscopy (100 frames/s) under Langendorff perfusion with 0.3 mM Ca 2+ -Tyrode solution including 0.4 % saponin at 30°C. Also performed was confocal imaging of tetramethylrhodamine methyl ester (TMRM) fluorescence of the myocardium. Under quasi-quiescence of the heart after dissection of the SA node, individual myocytes barely exhibited spontaneous Ca 2+ waves, whereas after commencement of saponin perfusion high-frequency (118 ± 9.7 /min/cell, mean ± SEM) Ca 2+ waves (hereafter, “agonal waves”) emerged within 1 min, showing asynchronous, oscillatory contractions in the individual myocytes with a V prop of 124 ± 2.5 μm/s (n = 60). Subsequently, the waves gradually decreased in frequency with concomitant slowing of its decay time course, and eventually, disappeared in 6 min; myocytes exhibited high, static Fluo4-fluorescence intensity. Along with the progression of Ca 2+ overload by saponin, the TMRM fluorescence intensity was discretely lost in individual myocytes. The myocytes showing the agonal waves exhibited contraction bands, i.e., band-like aggregations of the actin fibers. Under mechanical arrest of the heart by 2,3-butanedione monoxime (20 mM), saponin still induced the agonal waves with a frequency of 253 ± 10.6 /cell/min and V prop of 118 ± 2.1 μm/s (n = 60); however, contraction bands were barely seen.In conclusion, irreversible myocyte injury by saponin provoked agonal Ca 2+ waves and oscillatory contractions indicating progressive Ca 2+ overload and the following mitochondrial damage, which may provide deeper insights into understanding the mechanism of contraction band necrosis.

Tyrosine phosphorylation following alterations in arteriolar intraluminal pressure and wall tension

2001 ◽  
Vol 281 (3) ◽  
pp. H1047-H1056 ◽  
Author(s):  
Timothy V. Murphy ◽  
Brian E. Spurrell ◽  
Michael A. Hill
Keyword(s):  
Tyrosine Phosphorylation ◽  
Fluorescence Intensity ◽  
Laser Scanning ◽  
Time Course ◽  
Transmural Pressure ◽  
Laser Scanning Microscopy ◽  
Intraluminal Pressure ◽  
Confocal Laser ◽  
Wall Tension ◽  
Myogenic Activity

Arterioles respond to increased transmural pressure with myogenic constriction. The present study investigated the role of tyrosine phosphorylation in myogenic activity. Cannulated segments of a rat cremaster arteriole were fixed under pressure, followed by incubation with fluorescein isothiocyanate (FITC)-conjugated anti-phosphotyrosine. Smooth muscle cell fluorescence intensity was measured with the use of confocal laser-scanning microscopy. Anti-phosphotyrosine fluorescence intensity in muscle cells of arterioles maintained at 100 mmHg was reduced by the tyrosine kinase inhibitor tyrphostin A47 (30 μM) and increased by the tyrosine phosphatase inhibitor pervanadate (100 μM). In time-course experiments, anti-phosphotyrosine fluorescence increased slowly (over 5 min) after an acute increase in intraluminal pressure, and was dissociated from myogenic contraction (within 1 min). In contrast, angiotensin II (0.1 μM) caused rapid constriction and increased tyrosine phosphorylation. Anti-phosphotyrosine fluorescence was also pressure dependent (10–100 mmHg). Abolition of myogenic activity, either through removal of extracellular Ca2+, or exposure to verapamil (5 μM) or forskolin (0.1 μM) caused a further increase in anti-phosphotyrosine fluorescence. We conclude that transmural pressure and/or wall tension in arterioles causes increased tyrosine phosphorylation; however, this is not involved in the acute phase of myogenic constriction but may be involved in later responses, such as sustained myogenic tone or mechanisms possibly related to growth.

Automated Fluorometric Analysis of Calcium Pantothenate in Multivitamin Preparations

1978 ◽  
Vol 61 (3) ◽  
pp. 720-726
Author(s):  
Ram B Roy ◽  
Anthony Buccafuri
Keyword(s):  
Acid Solution ◽  
Boric Acid ◽  
Fluorescence Intensity ◽  
Analytical Data ◽  
Boric Acid Solution ◽  
Calcium Pantothenate ◽  
Magnesium Trisilicate ◽  
On Line ◽  
The Mean ◽  
Fluorometric Analysis

Abstract An automated fluorometric procedure is described for assaying calcium pantothenate in multivitamin preparations. Sample extracts containing calcium pantothenate are treated on-line with a slurry of magnesium trisilicate which removes any interfering riboflavin that may be present. The nitrate is resampled, mixed online with a slurry of Dowex 50W-X4 (H+) which removes any interfering β-alanine that may be present, and dialyzed. Dialysates are hydrolyzed in an alkaline medium and reacted with a mixture of o-phthalaldehyde and 2-mercaptoethanoI in boric acid solution. The fluorescence intensity due to the formation of a fluorogenic compound is measured at 455 nm after excitation at 350 nm. The procedure developed is capable of analyzing 20 samples/hr. Analytical data indicate that calcium pantothenate is assayed reliably both from real and synthetic multivitamin preparations. The mean recovery of calcium pantothenate added to sample solutions of tablet composites was 95.4%.

scholarly journals J-PLUS: Morphological star/galaxy classification by PDF analysis

2019 ◽  
Vol 622 ◽  
pp. A177 ◽  
Author(s):  
C. López-Sanjuan ◽  
H. Vázquez Ramió ◽  
J. Varela ◽  
D. Spinoso ◽  
R. E. Angulo ◽  
...  
Keyword(s):  
Population Distribution ◽  
Function Analysis ◽  
Normal Function ◽  
Compact Objects ◽  
Compact Stars ◽  
Bayesian Probability ◽  
Noise Sources ◽  
Future Version ◽  
Log Normal ◽  
Galaxy Classification

Aims. Our goal is to morphologically classify the sources identified in the images of the J-PLUS early data release (EDR) as compact (stars) or extended (galaxies) using a dedicated Bayesian classifier. Methods. J-PLUS sources exhibit two distinct populations in the r-band magnitude versus concentration plane, corresponding to compact and extended sources. We modelled the two-population distribution with a skewed Gaussian for compact objects and a log-normal function for the extended objects. The derived model and the number density prior based on J-PLUS EDR data were used to estimate the Bayesian probability that a source is a star or a galaxy. This procedure was applied pointing-by-pointing to account for varying observing conditions and sky positions. Finally, we combined the morphological information from the g, r, and i broad bands in order to improve the classification of low signal-to-noise sources. Results. The derived probabilities are used to compute the pointing-by-pointing number counts of stars and galaxies. The former increases as we approach the Milky Way disk, and the latter are similar across the probed area. The comparison with SDSS in the common regions is satisfactory up to r ~ 21, with consistent numbers of stars and galaxies, and consistent distributions in concentration and (g−i) colour spaces. Conclusions. We implement a morphological star/galaxy classifier based on probability distribution function analysis, providing meaningful probabilities for J-PLUS sources to one magnitude deeper (r ~ 21) than a classical Boolean classification. These probabilities are suited for the statistical study of 150 thousand stars and 101 thousand galaxies with 15 < r ≤ 21 present in the 31.7 deg2 of the J-PLUS EDR. In a future version of the classifier, we will include J-PLUS colour information from 12 photometric bands.

Application of the Silicon Photomultiplier for Fluorescence Photobleaching Measurement

2017 ◽  
Vol 1 (1) ◽  
pp. 11-16
Author(s):  
Łukasz Mik ◽  
Wojciech Kucewicz
Keyword(s):  
Bias Voltage ◽  
Fluorescence Intensity ◽  
Path Length ◽  
Measurement Method ◽  
Optical Path Length ◽  
Optical Path ◽  
Single Photons ◽  
Silicon Photomultiplier ◽  
Excitation Light ◽  
Fluorescence Light

In the paper a measurement method of fluorescence intensity reduction (called photobleaching) caused by excitation light was presented. Intensity of fluorescence light was measured by silicon photomultiplier (SiPM) – sensor which allows single photons detection. It has more compact dimensions and lower bias voltage in comparison to photomultiplier tube, presently used in many laboratory devices. Standard photometric cuvettes with a capacity of 1.6 ml and optical path length of 10 mm were used for the measurements. Sodium fluoresceinate dissolved in 10 mM TRIS buffer at pH 8.5 was used as the fluorescent dye. The solution was tested at a concentration of 100 μg per ml with constant excitation light from LED source over the time of measurement.

Hydraulic conductivity of deeply weathered materials in the Darling Range, Western Australia

Soil Research ◽  
1980 ◽  
Vol 18 (2) ◽  
pp. 129 ◽  
Author(s):  
AJ Peck ◽  
PA Yendle ◽  
FE Batini
Keyword(s):  
Hydraulic Conductivity ◽  
Western Australia ◽  
Gaussian Function ◽  
Normal Function ◽  
Test Method ◽  
Poor Correlation ◽  
Frequency Distributions ◽  
Grid Points ◽  
Log Normal ◽  
Made In

The hydraulic conductivity (K) of unconsolidated, deeply weathered material was measured by the slug test method In 214 boreholes distributed over five distinct areas in the Darling Range of Western Australia. Most of the measurements were made in the zone 0-3 m above hard rock. Theory of the method was extended to include a layer of material with lower K about the slotted pipe. The frequency distribution of K in each area was well fitted by the log-normal function. Parameters of the linear regression of logK against the inverse Gaussian function of cumulative frequency differed significantly (P<0.001) between areas. In one area of 134 ha, measurements were made in 54 boreholes located on a grid. There was a very poor correlation between values of K at the smallest separation of grid points (100 m), which suggests that there is an essentially random spatial variation of K measured by this method in this study area. Assuming log-normal frequency distributions and random spatial distributions, bulk conductivities were estimated for each area. On the basis of these investigations, it is concluded that the bulk hydraulic conductivity of the weathered material in the Darling Range is slow to moderately slow, and relatively uniform on the broad scale.

An in vitro study of Hoechst 33342 redistribution and its effects on cell viability

2005 ◽  
Vol 24 (11) ◽  
pp. 573-580 ◽  
Author(s):  
N Mohorko ◽  
N Kregar-Velikonja ◽  
G Repovs ◽  
M Gorensek ◽  
M Bresjanac
Keyword(s):  
Cell Death ◽  
Cell Transplantation ◽  
Fluorescence Intensity ◽  
Time Course ◽  
In Vitro Study ◽  
Host Cells ◽  
Hoechst 33342 ◽  
Overnight Incubation ◽  
Donor Cells

Although Hoechst 33342 (H342) is frequently used to label donor cells in cell transplantation research, it has been noted that it might secondarily label the host cells. Furthermore, its potential toxicity leading to cell death has been described. We studied the time course of H342 redistribution from the primary labeled rat bone marrow stromal cells (rBMSC) into the non-labeled rBMSC population over 7 days in culture; we evaluated the nuclear H342 fluorescence intensity as a possible criterion for distinguishing the primary from the secondary labeled cells, and determined the viability of rBMSC after an overnight incubation in 1 mg/mL of H342. H342 labeled / 50% of the initially non-labeled cells within the first 6 hours and almost 90% within a week.Nuclear fluorescence intensity was a reliable criterion for distinguishing primary and secondary labeled cells within the first 24 hours, but less so at later time points. The percentage of either apoptotic or necrotic cells did not rise acutely after the overnight incubation in 1 mg/mL of H342. Although a 12-hour incubation of rBMSC in 1 mg/mL of H342 did not cause acute cell death, H342 rapidly and extensively redistributed into non-labeled cells, which makes H342 a relatively unsuitable marker for cell transplantation research.

Calcium homeostasis in photoreceptor cells of Drosophila mutants inaC and trp studied with the pupil mechanism

1996 ◽  
Vol 13 (2) ◽  
pp. 257-263 ◽  
Author(s):  
Cornelia A. Hofstee ◽  
Doekele G. Stavenga
Keyword(s):  
Calcium Concentration ◽  
Light Adaptation ◽  
Photoreceptor Cells ◽  
Pupillary Response ◽  
Normal Function ◽  
Step Response ◽  
Pigment Granules ◽  
Reflectance Change ◽  
Log Normal

AbstractThe light-driven pupil mechanism, consisting of an assembly of mobile pigment granules inside the photoreceptor cells, has been investigated by in vivo reflection microspectrophotometry in wild type (WT) Drosophila and in the photoreceptor mutants inaC and trp. The pupillary response of a dark-adapted WT eye to a step in light is a monophasic reflectance increase reaching a plateau after ca. 15-s light adaptation. This reflectance change is due to photoreceptor pigment granules that accumulate near the tips of the rhabdomeres under light adaptation and that are withdrawn towards the periphery in the dark (Franceschini & Kirschfeld, 1976). The step response of the pupil mechanism of inaC is triphasic. Strikingly, the reflectance level at light onset is distinctly higher than that in WT, due to a partly aggregated state of the photoreceptor pigment granules near the rhabdomere tips that persists in the dark-adapted state, in line with direct calcium measurements of Peretz et al. (1994b). The step response of the pupil mechanism of inaC is slightly elevated compared to that of WT. The step response in trp is a transient, biphasic reflectance change, approximating a log normal function. This function is also a good approximation of the pulse response in WT and inaC. The intensity range of pupillary sensitivity is about 4 log unit. The range of inaC compared to that of WT is slightly (≈0.5 log unit) shifted towards lower intensities, but that in trp is strongly shifted to higher intensities (≈2.5 log unit). The results can be interpreted with the present knowledge of the primary steps in fly phototransduction and the hypothesis that the local intracellular calcium concentration determines the position of the pigment granules, and hence are in line with the notion that the pupil can be used as a qualitative Ca2+ probe.

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