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Results for “PHOTOELECTRIC CELL”

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At least 73 records · Page 4Linked to original sources
PubMed1994

[Auto-analysis of corneal endothelium with photoelectrical scans and computer].

A quantitative analysis of corneal endothelial cells was made with photoelectrical scans and computer in 67 eyes. No difference was found as regards to the mean cell area and density between the endothelial analysis system and routine square counting. On the other hand, we analyzed corneal endothelial cells between 30 eyes wearing hard contact lens and 30 eyes of age- and sex-matched nonwearing control. The parameters, including cell density individual cell area, area, mean cell area, standard deviation, coefficient of variation of cell size (CV), maximum cell, minimum cell, the ratio of the maximum to minimum cell, and percentage of the hexagoal cells, were automatically displayed. The cell density and mean cell area also showed no significant difference (P > 0.05) between the wearers and nonwearing control, but the CV and the frequency of the hexagonal cells showed significant difference (P < 0.01). The ratio of maximum to minimum cell, the polymegethism and pleomorphism were obviously increased in the wearers. It is highly suggested that computer analysis system is of great value in evaluating corneal endothelial cells.

Adolescent↗
PubMed1975

[Circadian rhythm of total histone concentration in noradrenalinergic and serotoninergic neurons and their glial satellite cells].

By means of photoelectric aperture cytospectrophotometry of fast green FCF strain sections the total histone content was determined in the nuclei and whole bodies of the neurons of the reticular formation, as well as in the nuclei of their glial satellite cells during various periods of the 24-hour cycle. In the noradrenalinergic neurons of the reticular formation of the lateral nucleus ther was revealed a circadian rhythm of the changes in the total histone content with the two maxima and the two minima per 24 hours in the neuronal bodies, but with only one period of fluctuations per 24 hours in their nuclei. On the contrary, in the 5-hydroxytryptaminergic (serotoninergic) neurons of the paragiant-cell nucleus of the reticular formation the total histone content changes once in 24 hours in the cell bodies, but twice within the same period in the neuronal nuclei. The amplitude of fluctuations was markedly lower than in the corresponding neurons in the cells of the perineuronal neuroganglia,

Animals↗
PubMed1988

Stimulation of ciliary activity by indomethacin in rabbit tracheal epithelial organ culture.

Inflammatory mediators influence mucociliary transport function in the lung, which may be dependent on the beating of the underlying cilia. To determine whether a nonsteroidal anti-inflammatory drug affects this function, and, if so, what is the mechanism action, we examined the effect of indomethacin on ciliary beat frequency (CBF) of cultured rabbit tracheal epithelial cells by a photoelectric technique. Addition of indomethacin dose-dependently enhanced CBF without any ciliary discoordination, the maximal increase and Km being 26.5 +/- 4.8% (mean +/- SE, p less than 0.001) and 6.8 X 10(-7) M, respectively. Pretreatment of tissues with nordihydroguaretic acid (10(-5) M), an inhibitor of the lipoxygenase pathway, did not change the baseline CBF, but inhibited the response of CBF to 3 X 10(-6) M indomethacin (p less than 0.01). These results suggest that indomethacin may accelerate mucociliary clearance through the augmentation of ciliary motility and that this ciliostimulation may be mediated by leukotrienes produced by activation of the lipoxygenase pathway of arachidonic acid metabolism.

Animals↗
PubMed1968

New turbidimetric device for measuring cell concentrations in thick microbial suspensions.

A photoelectric turbidimeter is described for use in measuring cell concentrations in thick suspensions. Its sample cuvette provides a path length continuously adjustable between 0.01 and 20.00 mm. By reducing the path length, it is possible to measure the optical density in thick cell suspensions without dilution. Moreover, the method described is rapid and simple, and only small amounts (less than 1 ml) of cell suspensions are required. The method is applicable to cell concentrations ranging up to 10(9)/ml for yeast.

Bacteria↗
PubMed1982

Length-tension relation of single smooth muscle cells isolated from the pedal retractor muscle of Mytilus edulis.

Single smooth muscle cells were isolated with an enzymatic dispersion procedure from the pedal retractor muscle (PRM) of Mytilus edulis. The isometric tension of the isolated cell was measured by photoelectrically recording the small, elastic displacement of one of the pair of micropipettes used to hold the ends of the cell by suction. Stimulation with a 0.1 ms rectangular current pulse elicited in the cell a twitch-like contraction which was comparable to that of the whole PRM in both time course an tension per unit cross-sectional area. The length-tension relation for maximal twitches showed that the isolated cell, like the whole PRM, can generate tension over a very wide range of lengths, that is from 0.2 to more that 2.0 Ls (where Ls is the shortest length which the resting cell assumes without any slack). No persistent tension was observed in the cell stretched up to 2.0 Ls, indicating that the passive tension observed in the whole PRM is caused by extracellular material.

Animals↗
PubMedDate not supplied

[Effect of quinones and nitrofurans on Trypanosoma mega and Crithidia fasciculata].

Demonstration of trypanocidal effects in vitro is a first step for the development of new antichagasic drugs. In order to obtain an experimental model allowing the pre-screening of potential trypanocides for Trypanosoma cruzi in a short time and under safe conditions, the trypanosomatids T. mega and C. fasciculata were assayed for their response to a) compounds known for their action on T. cruzi, and b) compounds not tested before on the latter. The drugs were assayed on the organisms growth in a liquid culture medium, cell multiplication being measured by the medium turbidity increase, using a photoelectric colorimeter previously calibrated with cell suspensions of known concentration. A series of quinones (Lapachones and related compounds), naftoquinone-imines, benzoquinones (perezone and dihydroperezone), a quinol (miconidine) and several nitrofurans, including nifurtimox and (5-nitro-2-furfurylidene)-amino (NF-group) derivatives, inhibited the flagellates growth, specially T. mega, with half-maximal inhibitory concentrations lesser than 5.0 microM, for the most active compounds. T. mega response to nifurtimox, NF-derivatives and beta-lapachone was in close agreement with that of T. cruzi. Cultures of T. mega in the presence of NF-pyrazole, NF-indazoles and NF-imidazole but not nifurtimox, showed irreversible damage since, after re-incubation in fresh medium without inhibitor, these cells grew significantly less than their corresponding controls. Similar effects were observed in C. fasciculata, with beta-lapachone and one naftoquinone-imine. Our results qualify T. mega as an adequate experimental model for the assay of antichagasic agents, as C. fasciculata and T. brucei brucei do for the african trypanosomes.

Animals↗
PubMed2000

Photoelectric measurements of s-BLM/nucleoli: a new technique for studying apoptosis.

A new method based on photoelectric measurement for analyzing apoptosis of cell-free MCF-7 nucleoli is reported. Supported bilayer lipid membrane (s-BLM) was used to enclose nucleoli in biological environment. The s-BLM was self-assembled on the wall of a super-thin cell. During the apoptosis induced by Taxol, the photoelectric current of the self-assembled s-BLM/nucleoli was found decreasing with time, suggesting the degradation of nucleus DNA. Electron transfer along the DNA double helix and along nuclear skeleton is assumed in the interpretation. This novel photoelectric analytical method may provide a rapid and sensitive technique to evaluate apoptosis.

Apoptosis↗
PubMed1995

Electromotile responses and frequency tuning of isolated outer hair cells of the guinea pig cochlea.

Isolated outer hair cells (OHC) of the guinea pig cochlea were exposed to external alternating electric fields parallel to the longitudinal axis of the cells. This resulted in oscillations of the cells' length that were measured photoelectrically using a ratiometric light amplifier. At 5 Hz and elongations up to 300 nm, amplitude of the cell length during oscillation was a linear function of the amplitude of the sinusoidal electric field. When increasing the stimulus frequency up to 32 kHz, OHC length changes followed the stimulus cycle-by-cycle. Oscillations at frequencies above 32 kHz escaped the experimental approach by their small amplitudes and could not be excluded. The frequency dependence of the motile response measured at 5-12,000 Hz had low-pass filter characteristics in cells of the second, third and fourth turns of the cochlea. However, frequency tuning of the motile response was absent in each OHC and systematic differences between different turns were not observed.

Animals↗
PubMedDate not supplied

[Role of a goal in determining neuronal activity of the motor and visual areas of the rabbit cortex].

In experiments on alert rabbits neuronal activity of the motor and visual cortical areas was studied in behavioural acts (BA) of grasping of a piece of plastics (P) and carrot (C) from consequently presented cups of the feeder; the animal had an opportunity to seize a C piece only after grasping and taking away from the previous cup the P piece. "Visual environment" in which BA were realized were identical; P and C pieces were identical in form and visual characteristics. Records were made of unit activity (201 cells), animal's movements (photoelectric method), EMG of the m. masseter; in parallel videorecords of behaviour were carried out. BA of P and C pieces grasping were identical in electromyo- and actographic characteristics; motor composition of these BA did not differ. 61 neurones were activated in both BA, 5--only in BA of P piece grasping, 22--only in BA of C piece grasping, i. e. 30% of neurones were activated only in one of the compared BA. Characteristics of activations, appearing in both acts could be significantly different: different frequency, connection with different stages of the compared BA. The obtained data are determined by changes of the motor and receptive fields of neurones in one BA in comparison to another, and are considered as an evidence supporting the suggestion that appearance of cortical neurones' activations in behaviour depends on BA goal and is not strictly determined by the parameters of movements and environment.

Animals↗