The retinal effects of copper vapor laser exposure.

The copper vapor laser is a pulsed gas laser which emits energy in two wavelengths simultaneously: 510.6 nm (green) and 578.2 nm (yellow). Each pulse has a duration of 15 nsec, maximal energy of 3 mJ and a peak power of more than 100 kW. It is a variably high repetition rate laser, in the range between 1 kHz and more than 20 kHz. We studied its interaction with the rabbit retina, while using two different repetition rates, 4 kHz and 18 kHz. The histological analysis of the lesion produced by 4 kHz repetition rate showed undesired retinal effects, similar to those caused by other pulsed lasers. On the other hand, the histological examination of the lesion produced by the 18 kHz repetition rate showed a desired coagulation effect, limited to the outer retinal layers, and comparable to a lesion produced by a continuous wave (CW) laser.

Metabolic changes induced in rat hippocampal slices by norepinephrine.

The oxidative metabolic activity of restricted regions of hippocampal slices was assessed by a continuous measurement of the fluorescence of intramitochondrial nicotinamide-adenine dinucleotide (NADH). A large increase in NADH fluorescence was triggered by substituting the oxygen supply to the slice by nitrogen gas. A large and transient increase in NADH fluorescence was also produced by superfusion of the the slice with a high (50 mM) potassium-containing medium. Addition of norepinephrine (NE) to the superfusion medium caused a propranolol-inhibited increase in NADH fluorescence. Furthermore, ouabain, which inhibits the Na-K pump, blocked the effects of NE. An analog of cyclic adenosine monophosphate (cAMP), 8-bromo cAMP, mimicked the effect of NE. Finally, effects of NE could still be produced in a kainic acid-treated hippocampus, where most neurons were previously destroyed by the drug. It is suggested that NE activates a Na-K-ATPase, that this effect might be mediated by cAMP, and that these interrelations may underly the physiological action of NE in the brain.

Effects of hyperbaric oxygenation on spermatozoan motility driven by mitochondrial respiration.

The effects of hyperbaric oxygen (HPO) on ram sperm motility driven by mitochondrial respiration are described. Sperm motility was assessed by a multichannel optical objective technique (Reflectospermiography). Motility was simultaneously measured from four semen sample at various pH levels in room air atmosphere and compared with four other samples exposed to various high oxygen (100%) levels 1, 3, 5, and 7 atmospheres absolute (ATA). Two main effects were observed under HPO oxygen: 1) shortening of motility durations, and 2) abolishment of motility regulation by pH. These effects were found to be attributed to the hyperoxic conditions. Above 3 ATA the effects of HPO with regard to the above-described parameters were considered toxic. Below this pressure level the effect of HPO was found to be moderate. The exposure of sperm cells to HPO (7 ATA) did not cause morphological alterations. Also, exposure of seminal plasma to HPO (7 ATA) for 150 min did not cause any toxic effects when added to washed spermatozoa. The ram semen preparation seems to provide a useful model for studying the mechanisms underlying HPO effects.

A fluorometric-reflectometric technique for simultaneous measurement of pH and motility in ram semen.

An optical technique for simultaneous assessment of pH and motility in ram semen was described. Motility was evaluated by the measurement of changes in intensity of reflected light from semen samples illuminated with 366 nm light. pH was measured by using a pH-sensitive fluorescent indicator (umbelliferone). From the changes in fluorescence intensity (450 nm) as a function of the pH of the semen, a calibration curve was constructed. The relationship between pH changes and motility in various metabolic conditions were described. Different kinetics for pH changes occurred when sperm motility was driven by both mitochondrial respiration and fructolysis or by either one of them. An analysis of the fluorescence signal from extracellular or cellular fractions of semen suggested that the pH measurement reflected extracellular pH.

Sperm cell motility as a new experimental model for toxicological studies.

The effects of environmental and toxicological factors were tested in a new and "simple" biological system; the collective motility exhibited by ram spermatozoa. Motility of highly concentrated semen (greater than 1 X 10(9) cells/ml) was evaluated objectively with a multichannel reflectospermiograph (RSG) connected to a minicomputer for an on-line analysis. The effect was tested on one of the energy-producing systems in the sperm cells, while the other was inhibited by 2-deoxy-D-glucose or antimycin-A so that the energy source for motility was known. The effects of the addition of ethanol to the semen in various concentrations, as well as various levels of oxygen in the environment were tested. When motility of the sperm cells was driven by mitochondrial respiration, the intensity and duration of motility was inhibited significantly above a threshold level. At the same level of ethanol, the motility was not significantly affected when the energy source was the fructolysis pathway. The effects of oxygen level were tested below and above the normal oxygen level (21% O2). When fructolysis was inhibited, the motility was fully dependent on oxygen supply, namely, that lower levels of oxygen inhibited motility. It was also found that under higher levels of O2 (hyperbaric hyperoxia conditions) the motility was inhibited due to the known oxygen toxicity effects.

A multi-channel system for the measurement of spermatozoan collective motility.

A new multi-channel optical system for objective evaluation of sperm motility is described. The principle of the technique is based on the measurement of changes in the intensity of light scattered from semen samples thermoregulated at 38 degrees C. These changes were recorded continuously as analog waves (Reflectospermiogram--RSG). Changes in the intensity of sperm motility as a function of time from ejaculation were simultaneously measured in 8 equal semen samples from single ejaculate. By analyzing the variations in results, the sensitivity of the technique was defined. In order to demonstrate the use of the technique, the effect of various concentrations of ethanol on sperm motility has been described. The exposure of sperm cells to 366 nm light used in the system did not alter their ultrastructure, as was observed by electron microscopy. This objective, relatively easy to perform and highly informative technique can be of great value in research studies.

The effect of pH on ram sperm collective motility driven by mitochondrial respiration.

Ram sperm cells treated with 0.02 M 2-deoxy-D-glucose exhibit collective motility which is driven only by mitochondrial respiration. This motility was measured, by means of multichannel optical objective technique, under various [H+] concentrations (pH range 5.6-7.2) buffered by 0.125 M phosphate buffers. Semen was divided into 8 aliquots and motility was monitored simultaneously for intensity and duration within 10 min of ejaculation until its complete cessation. The optimal pH range found for the two above-mentioned parameters was in the range of 6.0-6.5. A certain characteristic of the pattern of sperm motility intensity (an oscillations phenomenon) was similarly related to pH. It is suggested that the mechanisms underlying the relationship between pH and motility are rather metabolic. Concerning the results, some practical implications are introduced.

A new optical technique for evaluating collective motility of ram and bull ejaculated spermatozoa.

A new, non-destructive, objective technique for measuring collective motility of highly-concentrated ram and bull semen is described. The principle is based on changes in the reflected light scattered by motile spermatozoa. These changes can be recorded as a continuous analog wave pattern (Reflectospermiogram-RSG) and are correlated to the intensity of the turbulent motility as evaluated subjectively with an ordinary light microscope. Ram spermatozoa have, after ejaculation, a typical motility pattern, i.e., high, stable activity for about 20 min, then a period during which the motility decreases at a constant rate, and finally, a period with a low but rather constant activity. The usefulness of the technique has been demonstrated in various types of experiments.