Microphotometric Method Research Articles

Stereoselectivity of extraneuronal uptake of catecholamines in guinea-pig trachealis smooth muscle cells.

The extraneuronal uptake of the (-)- and (+)-isomers of three catecholamines, isoprenaline, adrenaline and noradrenaline, were compared in guinea-pig trachealis smooth muscle cells, by a fluorescence microphotometric method. Preliminary experiments showed that the initial rates of uptake of the (-)-isomers were greater than those of the (+)-isomers in tissues incubated in 25 microM adrenaline or noradrenaline or 50 microM isoprenaline. More detailed experiments showed that the Km values of the (+)-isomers of the amines for extraneuronal uptake were not significantly different from each other, but the Km value of (-)-isoprenaline less than (-)-adrenaline less than (-)-noradrenaline. Thus, the order of the ratios of the Km values for the (+):(-)-isomers was isoprenaline greater than adrenaline greater than noradrenaline. The results showed that there is stereoselectivity of the extraneuronal uptake of catecholamines, but it is greatest for isoprenaline (4.9 fold), less for adrenaline (2.5 fold) and almost negligible (1.6 fold) for noradrenaline.

Microphotometric determination of hematocrit in small vessels.

Evaluation and calibration of a microphotometric method for hematocrit determination in microvessels of transilluminated tissues is described. This method is based on the relation of the optical density (OD) of a microvessel to its hematocrit (Hct). The following requirements of the microphotometric system appear essential: narrow-band monochromatic light source with efficient false light suppression, high numerical aperture of the objective and low numerical aperture of the condensor. We used a video system to measure the intensities of incident (Io) and transmitted (I) light. For converting of Io and I into OD values, correcting procedures were evaluated to eliminate the influence of glare, shading, and fading. The calibration procedure was performed with glass tubes of inner diameter (ID) between 13 and 68 microns perfused with red cell suspensions. A function was fitted to the data, correlating OD to ID and Hct. The standard deviation of the original data from this function is +/- 0.02 units of fractional hematocrit. The presented method allows the continuous determination of the hematocrit in a microvessel as well as the off-line evaluation of the hematocrit distribution within a microvessel network.

Auxin increases the water permeability of Rhoeo and Allium epidermal cells

The ability of IAA to increase the permeability of plant cells to water was investigated in epidermal tissue of Rhoeo and Allium. At 10 −7 M, indole-3-acetic acid (IAA) enhanced the rate of deplasmolysis, measured visually, of Rhoeo epidermal cells and the stimulation was detectable as early as 1 min after IAA application. Indole-3-carboxylic acid (ICA), an inactive auxin analog, failed to promote deplasmolysis under similar conditions: 10 −4 M IAA was less stimulatory than 10 −7 M. A microphotometric method was used to monitor osmotically-induced swelling and shrinking of Allium epidermal cell protoplasts. IAA (10 −7 M) increased both the swelling and shrinking rates of Allium protoplasts within seconds of hormone addition. CaCl 2 (10 mM) antagonized auxin-stimulated swelling but had no effect on auxin-induced shrinking. The results suggest a rapid, direct enhancement of the water permeability of the plasma membrane in Rhoeo and Allium epidermal cells.

The nature of clinoptilolite from georgian beds

1. Study has been made of clinoptilolites from the Dzegvi and Khekardzula beds in Georgia, using x-ray and electron microscope microphotometric methods coupled with porisometric measurements. 2. The Khekardzula mineral consists of fine-grained crystalline clinoptilolite (≪ 1 μm) interspersed with coarse (∿5 μm) crystals of gypsum and heulandite. There is also the possibility that these samples contain a certain amount of an amorphous phase of unknown composition.

Quantitative immunoautoradiography at the cellular level. I. Design of a microphotometric method to quantitate membrane antigens on single cells using 125I-labeled antibodies

Iodine-125 has become a commonly-used radioisotope, especially for immunoautoradiographic investigations. Microphotometry of grain density, a well-established method in autoradiography with tritium and carbon-14, was applied to nucleated cells with 125I-labeled membranes. Geometric and absorption factors of radiation were investigated in order to find suitable conditions for quantitative evaluation. A preparatory device is given and a set-up of appropriate measuring conditions is presented. With these prerequisites the reflected-light bright-field photometry of immunoautoradiographs permits to determine automatically the content of surface antigens of single cells. Measurement examples were demonstrated.

Measurement of Strain Distribution in Plane Metal Plate by Optical Spatial Filtering

A new quantitative measurement of strain distributions is performed by optical spatial filtering in an optical differentiation system. In this method, the strain distribution can be converted to the light intensity distributions in the image plane, and three strain components can be obtained by a microphotometric method from only a single specimen without time-consuming numerical calculations, such as in Moiré or photoelastic photoelastic methods. An experimental example is performed in order to show the practical usefulness of the present method, and some considerations on deterioration in the fidelity of the system performance are also given.

Myonemal contraction of Spirostomum. I. Kinetics of contraction and relaxation.

AbstractA microphotometric method is introduced that allows measurement of the contraction‐relaxation kinetics of Spirostomum in response to electrical stimulation. The time course of contraction includes a rapidly contracting phase of some 4–5 mS during which cells shorten at a rate in excess of 100 cell lengths sec−1. While a stimulus strength‐duration curve determines the threshold of the response, the response to above threshold stimuli of different strengths and to trains of stimuli suggest that contraction of Spirostomum may not be an all‐or‐none event. The kinetics of relaxation following high stimulating voltages and repetitive after contractions also induced by high voltages are explained by excitation‐contraction coupling through a stimulus‐dependent intermediate effector, possibly the release of calcium ions. Changes in resting membrane potential detected by intracellular recording do not influence the initiation of contraction, while microinjection of calcium buffers above 10−5 M Ca2+ invariably induces contraction.

QUANTITATIVE RELATIONSHIPS OF CELLULAR PROTEIN, RNA, AND NUCLEARHISTONE IN HEXAPLOID TRITICALE AS INFLUENCED BY SOURCE OF WHEAT CYTOPLASM

Reciprocal F1 hybrids of hexaploid triticale (× Triticosecale Wittmack) differing only in their source of wheat (Triticum sp.) cytoplasm were studied to determine its influence on the synthesis of cellular protein and related compounds. Microphotometric methods revealed higher levels of total cellular protein and RNA in triticales with hexaploid-wheat cytoplasm (T. aestivum L. em Thell) than those with tetraploid wheat cytoplasm (T. durum Desf.). Conversely a higher level of nuclear histone was found in tritical hybrids possessing tetraploid wheat cytoplasm. The utilization of hexaploid-wheat cytoplasm in the improvement of the agronomic performance of hexaploid triticale is suggested.

Microscopic observation of the chorioallantoic capillary bed of chicken embryos

Using a method of rapid freezing and freeze-drying, the chorioallantoic vascular plexus which plays an important role in embryonic gas exchange was investigated microscopically in connection with a microphotometric method for measuring reaction rates of O 2 or CO with the red cells in the chorioallantoic capillaries. The capillary bed forms a thin layer on the outer surface of the chorioallantoic membrane and has a fine reticulate formation, unlike that of the mammalian alveolar capillary. Length of the capillary between bifurcations is approximately the size of the blood cell. Therefore, the cells flowing zigzag through the capillaries are deformed within its walls. The number of blood cells in the capillary bed increases with the progress of incubation. These observations may relate to the daily increase in diffusing capacity in embryonic gas exchange and somewhat effect the reaction rate.

Immunofluorescence microphotometry for the detection of platelet antibodies. I. Standardization of the method.

The standardization is described of an immunofluorescent microphotometric method that offers a solution for the problems generally encountered in immunofluorescence procedures on platelets. Fluorescein isothiocyanate (FITC) conjugated .anti‐immunoglobulin serum and anti‐IgG serum were used. Sera, containing isoor hetero‐antibodies against platelets that had given positive reactions with one or more of the conventional serological techniques, were used as positive controls. The method described proved to have a good reproducibility. Significant differences in fluorescence were obtained using the above‐mentioned positive sera and normal control sera. It was found that platelets stored in sodium‐azide could be used as antigen. A number of variables that may influence the difference in fluorescence obtained with positive and normal sera were studied.

An electron diffraction study of the molecular structure of BIS(trifluoromethyl) monoselenide

The molecular structure of (F 3C) 2Se has been determined in the vapour phase by the sector microphotometer method of electron diffraction. Two structures, differing essentially in the angles of rotation of the CF 3- groups about the C-Se bonds, are in good agreement with the data. The mean C-Se and C-F bond lengths are 1.978 and 1.333 Å, respectively.

An electron diffraction determination of the molecular structure of BIS(trifluoromethyl) diselenide

The molecular structure of F 3CSeSeCF 3 has been determined in the vapour phase by the sector microphotometer method of electron diffraction. The data are consistent with a C 2 model having the dimensions: C-F 1.326±0.005, C-Se 2.018±0.020, Se-Se 2.292±0.010 Å, angle F-C-Se 109.1±0.8°, angle C-Se-Se 98.0±0.5°, C-Se-Se-C dihedral angle 84.5±3.0°, and an angle of twist of 11.8±1.0° of both F 3C- groups from the conformation in which they are staggered with respect to the Se-Se bond.

An electron diffraction determination of the molecular structure of trifluoromethyl selenium cyanide

The molecular structure of F 3CSeCN has been determined, in the vapour phase by the sector microphotometer method of electron diffraction. Two molecular conformations are consistent with the experimental data; for the physically more reasonable structure, the principal parameters are: C-F 1.332 ± 0.007, Se-C(F 3) 1.984± 0.020, Se-C(N) 1.854 ± 0.016, N-C 1.152±0.020 Å and angle C-Se-C, 92.2 ± 2.0°.

An electron diffraction determination of the molecular structures of trichloro- and trifluoro-silyl-dimethylamine

The molecular structures of Cl 3SiNMe 2 and F 3SiNMe 2 have been determined in the vapour phase by the sector microphotometer method of electron diffraction. Both molecules are found to possess planar heavy-atom skeletons, after a small correction for shrinkage. The principal bond lengths are: Si-Cl = 2.023 ± 0.005, Si-F = 1.567 ± 0.006, Si-N = 1.657 ± 0.012 and 1.654 ± 0.015 Å, respectively, C-N = 1.446 ± 0.012 and 1.433 ± 0.015 Å respectively.

An electron diffraction determination of the molecular structure of trifluorosilyl isocyanate

The molecular structure of F 3SiNCO has been determined in the vapour phase by the sector microphotometer method of electron diffraction. The data are consistent with an Si-N-C angle of 160.7±1.2°, and Si-F and Si-N bond lengths of 1.553±0.004 and 1.648±0.010 Å respectively; the N-C and C-O bond lengths are strongly correlated with each other. The problems of interpretation of the electron diffraction structure are discussed in the light of a possible low Si-N-C deformation frequency.

An electron diffraction determination of the molecular structures of perchlorodisiloxane and methoxytrifluorosilane

The molecular structures of (Cl 3Si) 2O and F 3SiOCH 3 have been determined in the vapour phase by the sector microphotometer method of electron diffraction. For (Cl 3Si) 2O a C 2 model with an “ angle of twist ” of 29° is preferred.

An electron diffraction determination of the molecular structure of methyl silyl ether

The molecular structure of methyl silyl ether CH 3OSiH 3, has been deter- mined in the gas phase by the sector microphotometer method of electron, diffrac- tion. The Si-O bond length is 1.640±0.003 Å, the C-O bond length is 1.418±0.009 Å, and the Si-O-C angle is 120.6±0.9°.

Determination of the molecular structure of N-Difluoroboryl-disilazane by electron diffraction

The structure of (SiH 3) 2NBF 2 in the vapour phase has been determined by the sector microphotometer method of electron diffraction. The Si 2NB and NBF 2 units are planar, but there is some evidence that the second plane is slightly twisted with respect to the first. The principal bond lengths and angles are: Si-N = 1.737± 0.004 Å, N-B = 1.496±0.017 Å, B-F = 1.330±0.006 Å, Si-N-Si = 123.9±0.3° and F-B-F = 123.2±1.8°.

Étude optique de la zinkénite (Pb Sb2S4). Détermination de l'indice de réfraction, du cœfficient d'absorption et de l'indice d'absorption sur sections orientées

Reflectivity data for zinkenite in air and oil on (0001) and (10-10) sections were obtained using microphotometric methods under normal incidence. Measurements were made in monochromatic light of wavelengths from 440 to 660 nm. The refractive indices, the coefficients of absorption and absorption indices in the two principal directions of vibration of the crystal were calculated. Dispersion curves of all optical constants are given. The samples were identified by X-ray diffraction and its chemical composition established by X-ray fluorescence analysis.

Molecular structures of digermyl ether and digermyl sulphide in the gas phase, studied by electron diffraction

The structures of digermyl ether and digermyl sulphide have been determined in the gas phase by the sector microphotometer method of electron diffraction. The principal parameters for digermyl ether are: r(Ge–O)= 1·766 ± 0·004 A, r(Ge–H)= 1·531 ± 0·011 A, ∠(Ge–O–Ge)= 126·5 ± 0·4°: for digermyl sulphide, r(Ge–S)= 2·209 ± 0·004 A, r(Ge–H)= 1·512 ± 0·016 A, ∠(Ge–S–Ge)= 98·9 ± 0·3°.