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At least 55 records · Page 3Linked to original sources
PubMed1987

[Dosimetry of solar ultraviolet radiation. Daily and monthly changes in Paris].

The intensity of ultraviolet A and B radiations was measured in Paris (48 degrees North) by means of silicon photoelectric cells (Osram Centra dosimeter) from December, 1984 till February, 1986. The results, which must be regarded as approximate, are expressed as physical units (mW/cm2) and biological units (minimal erythema dose/hour). For sunny days two curves are presented separately for UVB and UVA: daily variations in radiation (hourly measurements) and daily variations at 11 hours (solar time) during one year. Maximum irradiation was observed at noon in early July: UVB 0.15 mW/cm2, UVA 5.4 mW/cm2. Between December and July the amount of UVB radiation was multiplied by 14 and that of UVA radiation by 9. For subjects with clear photo-type and when the sun was at its zenith, an MED per hour was obtained from May 1 onwards. Within a day, 30 p. 100 (summer) and 50 p. 100 (winter) of erythema-producing UV intensity were delivered between 11 and 13 hours (solar time). This kind of study has numerous clinical applications: advice regarding exposure to sun rays, dosing of heliotherapy, epidemiological data concerning photodermatitis (circumstances of exposure, UV threshold dose) and photocarcinogenesis (determination of annual MED doses in relation to areas of uncovered skin and occupational exposure to sun rays). Other studies on the French territory will provide a map of UV irradiation.

Paris↗
PubMed1979

Speed of response characteristics of goalkeepers: a descriptive and developmental report.

Photoelectric cells and accelerometers enabled the measurement of reaction, movement and total response times of the limbs of representative goalkeepers (N = 12) from five levels of organized hockey, under simple and choice test conditions. Speed of response characteristics fundamental to success at these levels of competition and the developmental improvement, which must occur annually to permit progress through the goalkeeping hierarchy, were suggested. The point at which the beginner's "reaction-type" pattern of goaltending must be augmented with "anticipation-type" behavior was explored. The concept that the ability to react and move is specific to the direction of the response was upheld at all levels of investigation. Standard deviation of the RT/MT/TRT's of each group reflected the degree of variability of performance that is tolerable at each level. This variability generally decreased with each ascending level within both testing conditions, with the exception of the CRT measures. Data collected over a two year period, for four subjects, revealed that the most evident longitudinal changes occurred in MT and that the youngest player experienced the greatest degree of overall improvement.

Adolescent↗
PubMedDate not supplied

Simultaneous assessment of the opiate-induced modifications in the vertical and horizontal components of locomotor activity in mice.

The effects of some opiates on the horizontal and vertical components of locomotor activity in mice were measured in actometers fitted with photoelectric cells counting horizontal displacements and the striding over a low partition wall. Morphine and fentanyl, used at low doses which did not modify the horizontal locomotor activity, decreased the striding over of the partition wall. Such a dissociation was not observed with either kappa or sigma agonists which affected in the same way the two components of the locomotor activity: both components were inhibited by kappa agonists and slightly stimulated by the sigma agonist SKF 10047. Although the opiate-induced inhibition of the striding over was induced by low doses of morphine, relatively high doses of naloxone were necessary for its antagonism. This apparently difficult antagonism could result in fact from the sedation which appeared when morphine was associated with naloxone.

Animals↗
PubMed1983

Inhibition of the spontaneous climbing behavior elicited in mice by opiates.

The spontaneous climbing behavior (SCB) developed by naive mice when they are introduced into small individual cylindrical cages with walls of vertical bars is inhibited in a dose-dependent manner by all the tested opiates. Only nalorphine administered over a large scale of doses never completely inhibits the SCB; its maximal effect is only about 50% of total inhibition. The efficacy of opiates on this special component of the locomotor activity has been compared with that on the horizontal displacements measured with an actometer equipped with photoelectric cells. Whereas the drugs known as specific kappa agonists depress both the horizontal locomotor activity and the SCB, most of the other tested opiates inhibit the SCB at doses which do not modify the horizontal locomotion. The low efficacy of loperamide, an opiate agent crossing the blood-brain barrier with difficulty, as well as the strong efficacy of a morphine low dose injected i.c.v. suggest that the opiate-induced SCB inhibition is centrally mediated. Finally, the involvement of mu and kappa receptors is discussed from the observed interactions with various opiate agonists, partial agonist (nalorphine) and antagonists (naloxone and diprenorphine).

Animals↗
PubMed1984

[Influence of bandages on the strength of impact of punches in boxing].

In boxing, a punch can be directed to the head or the torso of the opponent; however, because of the gravity of the ensuing injuries, the limit of tolerance of the head and face to repeated impacts (Gurjian, 1955, 1962; Patrick, 1955; Hodgson and Nakamura, 1968) is particularly important to keep in mind. The objective of this research was to compare the impact forces which could be attained barehand versus those obtained with different types of bandages made up of gauze and diachylon. For the purpose of this study, 22 boxers were selected. The impact force was measured with a Kistler force plate, covered with a synthetic mattress. A system of photoelectric cells was used to measure the velocity of the punch. Each boxer had to impact the target with 10 punches while his hand was covered with one of four types of bandages as well as barehand. This study has shown that the bandaged hand increases significantly the impact force of the punch. The force increases in relation to the thickness of the bandage. The use of additional pieces of diachylon has a greater influence than gauzes. Therefore, it can be concluded that the bandaging increases the rigidity of the hand and facilitates the transfer of the force in comparison to a similar punch without a bandage or with a thinner one.

Adolescent↗
PubMed1982

Tennis: the influence of grip tightness on reaction impulse and rebound velocity.

The effect of grip firmness between a tennis racket and a mobile hitting arm on post-impact ball velocity and reaction impulse have been investigated. A pneumatically driven racket-arm was triggered by a stimulus from a photoelectric cell positioned at the exit nozzle of a ball machine so that impact occurred with the racket perpendicular to the path of the ball. Tennis balls were fired to strike each horizontally positioned racket at four locations: the geometric center of the strings, 5 cm from the center towards the distal end, 5 cm closer to the shaft from the center, and 5 cm above the center. The average horizontal velocity of the ball, both before and after impact, was determined by using stroboscope photography. Reaction impulse (the integral of the force recorded following impact over a period of 50 ms), collected using Kistler force transducers, was photographed from a storage oscilloscope and measured over the 50 ms with a digitizer. A non-significant increase in rebound coefficient and reaction impulse in the direction of the hit were recorded for central impacts with an increase in grip tension. The largest rebound coefficients, and therefore the rebounds with the highest velocity, occurred at the center of the strings with a tight grip. Decreases in rebound coefficients and increases in reaction impulses were recorded for off-center impacts when compared to the central impacts. Significant increases in rebound coefficients were recorded for an increase in grip pressure for off-center impacts.

Biophysical Phenomena↗
PubMedDate not supplied

[The fluorosis problem in Senegal: data evaluation and presentation of a new method for defluoridating the water supply].

Fluoride intoxication is a serious public health problem in Senegal. The concentration of fluoride ions in underground water in Senegal is higher than the acceptable standard (0.7 mg/l at 25 degrees C) varying between 5 and 15 mg/l according to the season. The hydrological pattern of fluoride ions in Senegalese water is presented. The high levels of fluoride ions are due to the presence of phosphate ores. The health problems associated with the ingestion of toxic doses (about 4 mg/l) are discussed. Epidemiological investigation shows that the intoxication in Senegal is serious. In addition to fluoride in drinking water, high levels are also found in food, particularly tea and vegetables. Nanofiltration is a low cost membrane-based process which can be used to eliminate fluoride from drinking waters. Also known as low pressure reverse osmosis, this process is selective for small molecules and ions. It can thus sterilize and partially demineralize water. Furthermore, it can require only small amounts of energy, such that it can be run from photoelectric cells.

Filtration↗
PubMedDate not supplied

[Principles and technicals studies of investigating photosensitivity of the skin (author's transl)].

The authors report the principles of investigating photosensitivity of the skin: objects of testing and some basic practical consideration (doses, laws of irradiance, choice of wavelength in a test). Artificial sources for irradiation are studied. Xenon arc lamp is the most suitable. Two main kinds of device are suitable for routine radiant energy measurement; the thermopile with linear spectral response and the photoelectric cells without linear relationship between wavelength and sensitivity. To delimit the emission of xenon arc, the authors use absorption filters (cut-off type). Irradiation monochromator is indispensable to much dermatological photobiology, especially action spectrum study. Methods of measurement, time course of the response dose response relationship, threshold response and action spectrum of normal and abnormal effects of light on the skin are described. Routine phototesting procedure enclose: minimal erythemal dose, phototest, photopatchtest. Technical study and interpretation are exposed. For the dermatologist, phototesting procedure is necessary for the diagnosis. Mechanism of photosensitivity (phototoxic or photoallergic reaction) and wavelength dependence have to be known for an appropriate treatment.

Dose-Response Relationship, Radiation↗
PubMed1982

A rapid photoelectric method for reading cell migration from agarose microdroplets.

A rapid photoelectric method for reading cell migration from agarose microdroplets is described. Practically instantaneous, the method eliminates drawing and planimetry and makes feasible the use of a wide range of antigen concentrations. The results obtained are similar to those obtained by planimetry, but the photoelectric method is more sensitive. Enhancement of migration as well as inhibition were significantly demonstrated by this method. Migration inhibition of immune mouse spleen cells was found to be bizonal, with 2 peaks, one at very low antigen concentrations (10(-3) microgram/ml ovalbumin) and one at 10 microgram/ml.

Animals↗
PubMed2004

Synchrotron radiation-based experimental determination of the optimal energy for cell radiotoxicity enhancement following photoelectric effect on stable iodinated compounds.

This study was designed to experimentally evaluate the optimal X-ray energy for increasing the radiation energy absorbed in tumours loaded with iodinated compounds, using the photoelectric effect. SQ20B human cells were irradiated with synchrotron monochromatic beam tuned at 32.8, 33.5, 50 and 70 keV. Two cell treatments were compared to the control: cells suspended in 10 mg ml(-1) of iodine radiological contrast agent or cells pre-exposed with 10 microM of iodo-desoxyuridine (IUdR) for 48 h. Our radiobiological end point was clonogenic cell survival. Cells irradiated with both iodine compounds exhibited a radiation sensitisation enhancement. Moreover, it was energy dependent, with a maximum at 50 keV. At this energy, the sensitisation calculated at 10% survival was equal to 2.03 for cells suspended in iodinated contrast agent and 2.60 for IUdR. Cells pretreated with IUdR had higher sensitisation factors over the energy range than for those suspended in iodine contrast agent. Also, their survival curves presented no shoulder, suggesting complex lethal damages from Auger electrons. Our results confirm the existence of the 50 keV energy optimum for a binary therapeutic irradiation based on the presence of stable iodine in tumours and an external irradiation. Monochromatic synchrotron radiotherapy concept is hence proposed for increasing the differential effect between healthy and cancerous tissue irradiation.

Carcinoma, Squamous Cell↗
PubMed1967

Photoelectric potential from photoreceptor cells in ventral eye of Limulus.

Intense colored light from a gas laser evokes a photoelectric potential in the photoreceptor cells of the ventral eye of Limulus. This potential has two components, both of which have the action spectrum of a rhodopsin with an absorbancy maximum at 530 nm. The evidence is consistent with the hypothesis that the photoelectric potential arises directly from the orderly array of rhodopsin molecules which are an integral part of the photoreceptor cell membrane.

Animals↗
PubMed2000

A novel express bioassay for detecting toxic substances in water by recording rhodopsin-mediated photoelectric responses in Chlamydomonas cell suspensions.

The influence of Cu2+, Zn2+, Cd2+, Pb2+ and formaldehyde on rhodopsin-mediated photoelectric responses in the green flagellate Chlamydomonas reinhardtii was investigated using three modifications of a recently developed population method for electrical recording (in nonoriented, phototactically preoriented (PO) and gravitactically preoriented cell suspensions). The addition of the heavy metal ions at concentrations several times lower than those known to affect swimming velocity and other physiological parameters in photosynthetic flagellates led to a rapid (one to several minutes) inhibition of the responses. Formaldehyde induced a significant temporary increase in the gravi-orientation of the cells simultaneously with an inhibition of their photoelectric cascade, photo-orientation and motility. The signals recorded in PO suspensions were more sensitive to all tested toxic substances than those recorded from nonoriented cells and indicated a switch from negative to positive phototaxis in the presence of the toxic substances. Of the two major components of the photoelectric cascade, the regenerative response was more sensitive to the tested heavy metal ions, but not to formaldehyde, than the photoreceptor current. The results obtained show that measurement of the photoinduced electrical responses in Chlamydomonas cell suspensions is a powerful novel bioassay for testing environmental pollutants in water samples.

Animals↗
PubMed1991

Platelet activating factor induced respiratory mucosal damage.

Human sinus mucosal specimens from eight normal individuals were exposed to platelet activating factor (PAF) at concentrations ranging from 10(-6) M to 10(-11) M in a humidified CO2 chamber at 37 degrees C. The mucosal surface of the specimens was recorded on video tapes and magnified 2,500 times on a 19-inch television (TV) monitor. Ciliary activity of each ciliated cell was photoelectrically measured on the TV monitor in real time. PAF induced mucosal damage which resulted in a coarse profile including ciliostasis and exfoliation of epithelial cells. The length of the incubation period in which the initial coarse profile occurred on the mucosal surface inversely correlated with the concentration of exposed PAF ranging from 10(-6) M to 10(-10) M with r = -0.712 (p less than 2 x 10(-4)). Both the control medium and 10(-8) M lysoPAF showed no effect on ciliary activity or mucosal surface alteration even after 24 hr of exposure. Significant ciliary inhibition was noted after 6 hr of exposure to PAF at concentrations of 10(-8) M and 10(-10) M (p less than 0.05). After 10 hr of exposure, significant ciliary inhibition (p less than 0.01) was noted at all concentrations. Inhibition occurred in a time- and dose-dependent manner. The length of the incubation period in which initial ciliostatis occurred and the level of PAF concentration showed an inverse correlation with r = -0.918 (p less than 10(-6)). These results indicate that PAF is cytotoxic to human respiratory mucosa.

Cilia↗
PubMed1995

Role of NO generation in beta-adrenoceptor-mediated stimulation of rabbit airway ciliary motility.

To determine possible contribution of nitric oxide (NO) to the stimulatory action of beta-adrenoceptor agonist on ciliary motility, we measured ciliary beat frequency (CBF) of rabbit cultured tracheal epithelial cells by photoelectric method and NO release by specific amperometric sensors for this molecule in vitro. Salbutamol increased CBF, an effect that was potentiated by superoxide dismutase. Pretreatment of cells with NG-nitro-L-arginine methyl ester (L-NAME) attenuated the salbutamol-induced increase in CBF, causing a rightward displacement of the concentration-response curve by 2-2.5 log units, whereas NG-nitro-D-arginine methyl ester had no effect. The inhibitory effect of L-NAME was reversed by L-arginine but not by D-arginine. Immersion of the NO-selective electrode in the medium containing epithelial cells detected baseline current of 4.6-14.5 pA, which was abolished by L-NAME. Salbutamol dose-dependently increased the concentration of NO in the medium, the maximal increase being 56.2 +/- 5.3 nM (mean +/- SE; P < 0.001). These results suggest that NO is spontaneously released by airway epithelium and that the enhanced release of this molecule may play a role in the beta-adrenoceptor-mediated stimulation of ciliary motility.

Albuterol↗
PubMed1983

Delayed hypersensitivity and migration inhibition in two lines of mice genetically selected for high or low responsiveness to phytohemagglutinin.

Delayed-type hypersensitivity (DTH) and cell migration inhibition (MI) were studied in two lines of mice genetically selected for the high (Hi/PHA) or low (Lo/PHA) in vitro response of their lymphoid cells to phytochemagglutinin (PHA). A rapid photoelectric procedure for reading cell migrations enabled the study of MI over a wide range (10 log) of antigen concentrations in vitro. Hi/PHA mice required immunization with a 10 times higher dose of ovalbumin (OVA) in Freund's complete adjuvant (FCA) than Lo/PHA mice for a comparable response in DTH (footpad swelling) and MI of their induced peritoneal exudate cells (PEC). Lo/PHA spleen showed marked bizonal MI on Day 5 after immunization with low doses (0.1 and 0.5 micrograms) of OVA in FCA, one peak being obtained in presence of in vitro concentrations of 10(-3) or 10(-2) micrograms/ml OVA and another peak at 1 or 10 micrograms/ml, whereas Hi/PHA spleen showed stimulation of migration. In contrast, MI in Lo/PHA spleen failed to persist beyond Day 19, whereas it appeared progressively in Hi/PHA spleen, being maximal by Day 27. Low-zone inhibition in Hi/PHA spleen and PEC was lacking or poor even after immunization with higher doses of OVA in FCA. The implications of these findings are discussed.

Animals↗