Effects of laser irradiation on immature olfactory neuroepithelial explants from the rat.

The photobiological effect of low-output laser irradiation on the maturation and regeneration of immature olfactory bipolar receptor cells of the rat was studied. The maturation and regeneration of the receptor cells of rat fetuses were quantified in neuroepithelial explants with morphometric analysis. The number of explants with outgrowth and the number and length of neuritic outgrowths were determined on a regular basis for 12 days. Explants in the experimental group were irradiated with a helium-neon laser using different incident energy densities (IED). Explants in the fluorescent light control group were exposed to fluorescent light for the same periods of time as those in the experimental group were exposed to laser irradiation. Explants in another control group were not exposed to laser or fluorescent light irradiation. The IED of 0.5 J/cm2 laser irradiation has been found to increase significantly the number of explants with outgrowth and the number and length of the outgrowths. Other laser IEDs or fluorescent light irradiation did not influence maturation or regeneration.

Smell and taste disorders, a study of 750 patients from the University of Pennsylvania Smell and Taste Center.

Smell and taste disorders are common in the general population, yet little is known about their nature or cause. This article describes a study of 750 patients with complaints of abnormal smell or taste perception from the University of Pennsylvania Smell and Taste Center, Philadelphia. Major findings suggest that: chemosensory dysfunction influences quality of life; complaints of taste loss usually reflect loss of smell function; upper respiratory infection, head trauma, and chronic nasal and paranasal sinus disease are the most common causes of the diminution of the sense of smell, with head trauma having the greatest loss; depression frequently accompanies chemosensory distortion; low body weight accompanies burning mouth syndrome; estrogens protect against loss of the sense of smell in postmenopausal women; zinc therapy may provide no benefit to patients with chemosensory dysfunction; and thyroid hormone function is associated with oral sensory distortion. The findings are discussed in relation to management of patients with chemosensory disturbances.

Photochemical effects of laser irradiation on neuritic outgrowth of olfactory neuroepithelial explants.

The photochemical effect of low-intensity laser irradiation (LILI) on the maturation and regeneration of olfactory-immature estrus day 15 (E15) and olfactory-mature estrus day 22 (E22) rat fetuses was studied. Neuritic outgrowths of olfactory bipolar receptor cells were quantified in olfactory neuroepithelial explants. Explants in the experimental groups were irradiated with a helium-neon laser using different incident energy densities (IEDs). Explants in another group were exposed to fluorescent light. Control explants did not receive laser or fluorescent light irradiation. Neuritic outgrowths were analyzed on a regular basis for 12 days. Analysis of variance was used to evaluate the data. The parameters of neuritic outgrowth in E15 fetuses showed a significant increase of 30% to 50% vs. the control with a single laser irradiation of 0.5 J/cm2 IED. The rate of neuritic outgrowth observed in the E22 fetuses was less than in the E15 fetuses. The parameters of neuritic outgrowth in E22 fetuses showed a significant and substantially greater percentage increase than in the E15 fetuses with daily laser irradiations of 0.05 and 0.5 J/cm2 IED when compared to the control. The magnitude of these increases appears to be of biological significance as well as statistical significance.

Influence of body tilt within the sagittal plane on odor identification performance.

Odor identification performance, nasal airflow resistance, blood pressure, and heart rate were assessed in 8 men and 8 women in the following body tilt positions within the sagittal plane: 0 degree (upright), 90 degrees (supine), 135 degrees, and 180 degrees (upside down). The order of testing across the tilt conditions was systematically counterbalanced using a Latin square procedure. Average odor identification performance decreased monotonically as a function of increased body tilt. Significant decreases in heart rate and blood pressure were observed as the body was tilted from the upright condition, although blood pressure was equivalent in the upright and upside down conditions. Nasal resistance was highly variable and was not systematically altered as a function of body tilt. These data support the hypothesis that olfactory function, like visual, auditory, and vestibular function, is significantly influenced by body position within a gravitational field.

Development of the audiometer and audiometry.

The authors consider the reasons why the induction coil audiometer was not widely adopted in clinical practise. The conclusion is that they offered little relevance to the management of hearing-impaired patients at that time, bearing in mind the state of therapeutics, surgery and contemporary aids to hearing.

Cochlear blood flow during stepwise bleeding and CO2 inhalation in the anaesthetized dog and cat.

Normal blood flow values, autoregulatory tendency and CO2 sensitivity of the cochlear blood vessels were studied in acute experiments in anesthetized, artificially ventilated dogs and cats. Cochlear blood flow was measured with the hydrogen-gas clearance technique using 100 mu platinum electrodes implanted into the perilymphatic space. Normal mean cochlear blood flow at normal systemic blood pressure and arterial pH values was found to be 30 +/- 7 ml . 100 g-1 . min-1 in the dog, and 16 +/- 5 ml . 100 g-1 . min-1 in the cat. There was no evidence of the existence of an autoregulatory mechanism of cochlear blood flow during stepwise bleeding in the dog. Blood flow seemed to follow passively the changes of arterial pressure. Cochlear blood flow increased by 79% on 5% CO2 inhalation in the cat, as a result of decreased vascular resistance. The relationship between arterial pCO2 values and cochlear blood flow proved to be exponential.

The biomedical effects of laser application.

This paper briefly reviews the authors' experimental and clinical use of lasers over a 20-year period, during which laser effects on 15 biological systems were studied. Low-energy laser radiation was found to have a stimulating effect on cells, and high-energy radiation had an inhibiting effect. The application of lasers to stimulate wound healing in cases of nonhealing ulcers is recommended.