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At least 649 records · Page 36Linked to original sources
PubMed1990

Intracellular Ca2+ measurement with Indo-1 in substrate-attached cells: advantages and special considerations.

The dual emission, Ca2+ sensitive fluorescent dye, Indo-1, offers several potential advantages over its dual excitation analogue, Fura-2. Most notable among these advantages are increased speed of measurement using dual wavelength photometry and the absence of a requirement for special quartz optics. Despite these potential advantages, only a tiny fraction of the microscopic studies of intracellular free calcium ([Ca2+]i) on substrate-attached cells has employed Indo-1. Among the reasons for the infrequent use of Indo-1 are the fact that it exhibits somewhat different spectral properties in the cytosol than it does in extracellular buffers, and the notion that it is much more sensitive to photobleaching than Fura-2. We report here that under our experimental conditions, Indo-1 photobleaching is small and does not noticeably affect the measurement of free Ca2+, even after 30 minutes of continuous illumination. We also report a new method for creating in situ standard curves that is easy, reproducible, and yields values for [Ca2+]i that are identical to those obtained with Fura-2. In addition, we have found that Indo-1 is less subject than Fura-2 to compartmentalization within subcellular organelles. These results provide baseline data to take advantage of the significant improvement afforded by Indo-1 in the measurement of rapid [Ca2+]i responses and the avoidance of compartmentalization artifacts during experiments of long duration.

Calcium↗
PubMed1982

A photometric study of the standard Philadelphia (Ph1) translocation of chronic myeloid leukemia (CML).

A newly developed form of high resolution microscope photometry has been employed in a study of the relationships between the chromosomes involved in the standard Philadelphia (Ph1) translocation of chronic myeloid leukemia (CML). The intention of the investigation was to provide quantitative data on the relative amount of material exchanged between the No. 9 and No. 22 chromosomes. A marked consistency in the amount of material lost from the Ph1 was observed, and the balanced nature of the standard Ph1 translocation was confirmed. The data are also in accordance with the concept of a reciprocal exchange between the No. 9 and No. 22 chromosomes.

Bone Marrow Cells↗
PubMed1990

Some photometric techniques for atmosphereless solar system bodies.

We discuss various photometric techniques and their absolute scales in relation to the information that can be derived from the relevant data. We also outline a new scattering model for atmosphereless bodies in the solar system and show how it fits Mariner 10 surface photometry of the planet Mercury. It is shown how important the correct scattering law is while deriving the topography by photoclinometry.

Astronomy↗
PubMed1995

Kinetic determination of nortriptyline in pharmaceutical samples by use of photometric and fluorimetric detection.

A fast kinetic method is proposed for the photometric and fluorimetric determination of nortriptyline hydrochloride. The method involves measuring the rate of formation of an adduct with 4-chloro-7-nitrobenzofurazan, which exhibits light absorption and fluorescent properties, and the use of a stopped-flow mixing technique, which facilitates application to automatic routine analyses. The reaction rate is measured within only 30 s. The detection limit is 0.12 micrograms ml-1 (photometry) and 0.18 micrograms ml-1 (fluorimetry) and the calibration graph is linear up to 60 micrograms ml-1 in both cases. The precision (as RSD) is less than 1.5%. The proposed method was satisfactorily used for direct analysis of pharmaceutical preparations and a mean recovery near 100% was obtained with both photometric and fluorimetric detection.

Hydrogen-Ion Concentration↗
PubMed1985

Pseudohyponatremia.

Pseudohyponatremia should be distinguished from true hyponatremia lest injudicious therapy be instituted. Pseudohyponatremia is caused by a displacement of serum water by elevated concentrations of serum lipids or proteins. Only two (flame photometry and indirect potentiometry) of the three current methods available for measuring serum sodium involve sample dilution and may consequently produce spuriously low sodium values. The third method (direct potentiometry) involves no sample dilution, and sodium measurements are unaffected by hyperlipidemia and hyperproteinemia. As all three methods for sodium measurements may coexist in a clinical laboratory, it is important for the physician to be aware not only of the serum value but also the method employed.

Blood Proteins↗
PubMed1995

Staurosporine affects calcium homeostasis in cultured bovine adrenal chromaffin cells.

These studies show that the potent, non-specific, protein kinase inhibitor, staurosporine, disrupts Ca2+ homeostasis in cultured bovine adrenal chromaffin cells. Staurosporine treatment reduces basal and A23187-stimulated catecholamine release from chromaffin cells, but does not inhibit activated Ca2+ influx. Furthermore, pretreatment with staurosporine also reduces Ca(2+)-stimulated catecholamine release from digitonin-permeabilized cells (t1/2, 40.6 min; IC50, 66.0 nm). However, staurosporine does not inhibit the rise in intracellular Ca2+ ([Ca2+]i) in response to nicotine stimulation as measured by fura-2 photometry. These studies demonstrate that staurosporine interferes with the secretory process at some step at or after the rise in [Ca2+]i in adrenal chromaffin cells. Examination of the effects of staurosporine on 45Ca2+ movement shows that staurosporine produces a slowly developing basal 45Ca2+ accumulation; after 30 min no significant change is observed, but by 120 min, 45Ca2+ accumulation is increased by 29.5%. Thapsigargin and 2,5-di-(tert-butyl)-1,4-benzohydroquinone (tBHQ), inhibitors of Ca(2+) ATPases, were used to determine whether staurosporine induced 45Ca2+ accumulation results from sequestration of 45Ca2+ within intracellular stores. While thapsigargin has no significant effect, concomitant treatment with tBHQ prevents the increase in 45Ca2+ uptake associated with staurosporine treatment. Therefore, the tBHQ-sensitive Ca2+ store, but not the thapsigargin/inositol 1,4,5-triphosphate-sensitive Ca2+ store, appears to be staurosporine-sensitive. Overall, these studies indicate that staurosporine reduces catecholamine release by interfering with Ca2+ homeostasis. Furthermore, this work suggests that a staurosporine-sensitive phosphoprotein(s) is involved with the regulation of Ca2+ homeostasis in bovine adrenal chromaffin cells.

Alkaloids↗
PubMed2005

Novel type of general protein assay using a chromogenic and fluorogenic amine-reactive probe.

We report on a new and simple one-reagent method for general protein assay. It makes use of one of two new reactive labeling reagents presented here (and referred to as pyrylium [Py] labels). These can be applied for both photometric and fluorometric protein assays at near neutral pHs at room temperature. The Py labels undergo a large spectral change on conjugation to the amino group of proteins and typically change their color from blue to red. Therefore, and unlike in other assays, there is no need to separate the unconjugated (blue) label from the red conjugate, which can be determined by direct photometry with a limit of detection of 1.2 microg/ml for human serum albumin. The assay can be extended to fluorometry because the fluorescence of the free Py label is weak (with a quantum yield of <1%) but increases strongly (to >40%) on conjugation. The strong fluorescence of the red conjugates can be determined directly and without interference by the blue (and weakly fluorescent) free label. The fluorometric assay resulted in a limit of detection of 60 ng/ml for bovine serum albumin (BSA). Validation of the fluorescence assay of blood plasma samples spiked with BSA gave recoveries in the range from 91 to 103%.

Amines↗
PubMed2005

Analysis of polyphenols in wines: correlation between total polyphenolic content and antioxidant potential from photometric measurements. Prediction of cultivars and vintage from capillary zone electrophoresis fingerprints using artificial neural network.

The polyphenols (some of them are also called phytoalexins, flavonols, flavanons, flavanonols, flavons, flavanols, and anthocyanines) are usually marked as potent antioxidants or radical scavengers which assist the body cells against oxidation. Polyphenols in wine are also considered to explain so called French paradox (long life aging and low number of coronary diseases despite of high alcohol and fat consumption). The total polyphenolic content (TPC) and total antioxidant potential (TAP) were determined by photometry and found strongly correlated. This finding suggests that the determination of TAP can be replaced by a more simple procedure of TPC determination. Capillary zone electrophoresis (CZE) with preconcentration by solid phase extraction (SPE) was applied for some polyphenols determination and for obtaining electropherograms of the SPE extracts (fingerprints). From mathematical evaluation of the fingerprints, prediction of cultivars and vintage using artificial neural networks (ANN) was done with more than 90% correct prediction. The study was performed on a set of 47 samples of young wines (vintage 1999-2002) from south Moravia (Czech Republic) and New South Wales (Australia).

Antioxidants↗
PubMed2005

A primer on radiometry.

Correctly measuring radiometric quantities and reporting radiometric data is essential in developing a more complete understanding of the requirements and polymerization kinetics of dental resin composites. Presented herein is an introduction to the fundamental concepts, quantities and units of radiometry. A brief discussion of photometry and how it differs from radiometry is also included. While the basic principles of radiometry are relatively straightforward, a great deal of attention must be paid to the details when performing radiometric measurements and reporting radiometric data. Meaningful radiometric measurements require very close attention to nomenclature and mathematical definitions. Radiometric, not photometric quantities should always be used, unless the goal is to report how the human eye perceives light.

Composite Resins↗
PubMed2005

Central retinal thickness is positively correlated with macular pigment optical density.

Macular pigment (MP) has been suggested to have a protective role in age-related macular degeneration by reducing the amount of oxidative stress on the retina. MP levels peak at the foveal center, where it is found predominantly in the receptor axon and inner plexiform layers of the retina. The purpose of this study was to investigate the relationship between central retinal thickness and macular pigment optical density in a group of healthy subjects. We report that macular pigment optical density (MPOD) has a significant and positive relationship with central retinal thickness as measured by optical coherence tomography. The strength of the observed relationship (r approximately 0.30) was independent of the technique used to measure MPOD, whether heterochromatic flicker photometry (HFP) or 2-wavelength autofluorescence (AF). Of note, there was no statistically demonstrable relationship between MPOD at an eccentricity of 1- or 2-degrees and central retinal thickness. This finding has important implications for future studies investigating MPOD, and its response to dietary modification/supplementation.

Adult↗
PubMed2006

Risk factors for age-related maculopathy are associated with a relative lack of macular pigment.

Macular pigment (MP) is composed of the two dietary carotenoids lutein (L) and zeaxanthin (Z), and is believed to protect against age-related maculopathy (ARM). This study was undertaken to investigate MP optical density with respect to risk factors for ARM, in 828 healthy subjects from an Irish population. MP optical density was measured psychophysically using heterochromatic flicker photometry, serum L and Z were quantified by HPLC, and dietary intake of L and Z was assessed using a validated food-frequency questionnaire. Clinical and personal details were also recorded, with particular attention directed towards risk factors for ARM. We report a statistically significant age-related decline in MP optical density (r2=0.082, p<0.01). Current and past smokers had lower average MP optical density than never smokers and this difference was statistically significant (p<0.01). Subjects with a confirmed family history of ARM had significantly lower levels of MP optical density than subjects with no known family history of disease (p<0.01). For each of these established risk factors, their statistically significant negative association with MP persisted after controlling for the other two, and also after controlling for other potentially confounding variables such as sex, cholesterol, dietary and serum L (p<0.01). In the absence of retinal pathology, and in advance of disease onset, the relative lack of MP seen in association with increasing age, tobacco use and family history of ARM supports the hypothesis that the enhanced risk that these variables represent for ARM may be attributable, at least in part, to a parallel deficiency of macular carotenoids.

Adult↗
PubMed2006

Partial neutralization of rain by seaspray: the case of Recôncavo, Bahia-Brazil.

In the Recôncavo of Bahia (located between 12 degrees 33' and 13 degrees 10'S and 38 degrees 00'and 39 degrees 00'W), there are significant discharges of SO(2) and NO(x) due to local, industrial and urban activities. The incoming air masses from the Atlantic Ocean are enriched with seaspray, which neutralizes part of the rain acidity. The extent of seaspray neutralization of rain acidity was quantified in four sites of the region, each with different loads of seaspray. Rain samples were obtained daily at the same time, integrating the precipitation of the previous 24h, using wet-only collectors and analyzed for pH by potentiometry and for sodium by flame photometry. The amount of rain acidity in Recôncavo neutralized by seaspray ranged from <1% up to 88% and depended on the site. On average, neutralization ranged from 5% to 18%.

Acid Rain↗
PubMed2005

Limits of thermoluminescence dosimetry using quartz extracted from recent building materials in urban settlements.

The luminescence of quartz extracted from recently fired building material is known to detect doses of few mGy and can be successfully employed in the case of large scale radiation exposures due to nuclear accidents or terrorist acts. One brick and two tiles (50-80 years range) collected from an urban settlement were used to test the realistic minimum detectable dose limits of retrospective luminescence dosimetry. Independent methods like alpha counting, beta dosimetry, gamma spectrometry and flame photometry were used for the annual dose assessment. Two approaches were employed for the evaluation of the total accrued dose: regenerative dose and additive dose. The former allows the assessment of doses due to anthropogenic sources of radiation as low as approximately 12 mGy by using 10-year-old samples, but it can be applied only in samples showing no sensitisation. The latter can be applied to any sample, however, the related uncertainty is higher and minimum detectable anthropogenic dose in young samples amounts to 20 mGy.

Cities↗
PubMed2004

Enhancement of bone formation in rat calvarial bone defects using low-level laser therapy.

OBJECTIVE: To evaluate the effect of low-level laser therapy (LLLT), using a GaAlAs diode laser device, on bone healing and growth in rat calvarial bone defects. STUDY DESIGN: An animal trial of 4 weeks' duration was conducted using a randomized blind, placebo-controlled design. Standardized round osseous defects of 2.7 mm diameter were made in each parietal bone of 20 rats (n=40 defects). The animals were randomly divided into an experimental and a control group of 10 animals each. In the experimental group, a GaAlAs diode laser was applied immediately after surgery and then daily for 6 consecutive days. The control group received the same handling and treatment, but with the laser turned off. Five rats from each group were killed on day 14 and the remainder on day 28 postoperatively. From each animal, tissue samples from one defect were prepared for histochemistry and samples from the contralateral defect for histology. Levels of calcium, phosphorus, and protein were determined by using atomic absorption spectrometry, colorimetry, and photometry, respectively. Student t-test and Mann-Whitney were used for statistical analyses. RESULTS: At both time points the tissue samples from the experimental animals contained significantly more calcium, phosphorus, and protein than the controls. Similarly, histological analyses disclosed more pronounced angiogenesis and connective tissue formation, and more advanced bone formation in the experimental group than in the controls. CONCLUSION: LLLT may enhance bone formation in rat calvarial bone defects.

Aluminum↗
PubMed2004

Identification of a protanomalous chimpanzee by molecular genetic and electroretinogram analyses.

We determined the structures of long (L)-wavelength-sensitive and middle (M)-wavelength-sensitive opsin gene array of 58 male chimpanzees and we investigated relative sensitivity to red and green lights by electroretinogram flicker photometry. One subject had protanomalous color vision, while others had normal color vision. Unlike in humans, a polymorphic difference in the copy number of the genes and a polymorphic base substitution at amino acid position 180 were not frequently observed in chimpanzees.

Animals↗
PubMed1976

The significance of random sample size in flow-through photometric prescreening in cervical cytology.

The determination of nuclear DNA content by flow-through photometry is employed as a prescreening procedure in cervical cytology. The goal of a prescreening procedure is to obtain the smallest possible number of false negative findings with an economically acceptable number of false positive findings, which must be retested. False negative findings result from the often low relative frequency of atypical cells in a mixed population of normal and atypical cells. Only between 10,000 and 50,000 cells are contained in a random sample from the total suspended smear material. It was the purpose of this study to investigate whether a flow-through photometric study of the entire suspension and thus the larger absolute frequency of atypical cells mught lead to a decrease in false negative results. Flow-through photometric evaluation of the entire smear material is not superior to measurement of a random sample of 10,000-50,000 cells. 1. The relative frequency of atypical cells is unchanged, and thus also the proportion of false negative findings. 2. The number of false positive findings increases by 10% due to the inclusion of aggregates at the bottom of the preparation. 3. The measuring time is increased 10-fold, thus making the prescreening procedure uneconomical.

Cell Count↗
PubMed1986

Dihematoporphyrin ether clearance in primate bladders.

The techniques of in vivo tissue fluorescence photometry and chemical extractions of DHE, which have been recently developed in our laboratory, were employed to study DHE uptake and clearance in the primate bladders. Data show these techniques are readily applicable in studying porphyrin uptake and clearance in primate bladders. Quantitatively a correlation between fluorescence values and tissue extracted DHE values is found. Serum clearance and bladder clearance of DHE appeared phasic, but bladder clearance was slower than serum. The significance of these two methods lies in their applications in determination of drug dosimetry and optimum time for photoactivation in clinical photodynamic therapy.

Animals↗
PubMed1999

L, M and L-M hybrid cone photopigments in man: deriving lambda max from flicker photometric spectral sensitivities.

Using heterochromatic flicker photometry, we have measured the corneal spectral sensitivities of the X-chromosome-linked photopigments in 40 dichromats, 37 of whom have a single opsin gene in their tandem array. The photopigments encoded by their genes include: the alanine variant of the normal middle-wavelength sensitive photopigment, M(A180); the alanine and serine variants of the normal long-wavelength sensitive photopigment, L(A180) and L(S180); four different L-M hybrid or anomalous photopigments, L2M3(A180), L3M4(S180), L4M5(A180) and L4M5(S180); and two variants of the L-cone photopigment, encoded by genes with embedded M-cone exon two sequences, L(M2; A180) and L(M2; S180). The peak absorbances (lambda max) of the underlying photopigment spectra associated with each genotype were estimated by correcting the corneal spectral sensitivities back to the retinal level, after removing the effects of the macular and lens pigments and fitting a template of fixed shape to the dilute photopigment spectrum. Details of the genotype-phenotype correlations are summarized elsewhere (Sharpe, L. T., Stockman, A., Jägle, H., Knau, H., Klausen, G., Reitner, A. et al. (1998). J. Neuroscience, 18, 10053-10069). Here, we present the individual corneal spectral sensitivities for the first time as well as details and a comparison of three analyses used to estimate the lambda max values, including one in which the lens and macular pigment densities of each observer were individually measured.

Adult↗