Influence of 2,5-Hexanedione, Acrylamide, Tri-O-Tolyl Phosphate, Leptophos and Methylmercury on Endogenous Levels of Tryptophan, Serotonin and 5-Hydroxyindoleacetic Acid and Serotonin Turnover Rates in Rat Brain

Several industrial and environmental chemicals cause distal and/or central neuropathy among other diverse toxic effects. Spague-Dawley derived rats were fed doses of 2,5-hexanedione, acrylamide, tri-o-tolyl phosphate, leptophos and methylmercury via gavage. The dose levels and administration periods were established in previous experiments designed to assess clinical neuropathy using rats trained to walk on a rotorod apparatus fitted with an electrode floor. After intravenous injections of 3H-Tryptophan, whole rat brain homogenates were analyzed using liquid scintillation and spectrofluorometric techniques for levels of tryptophan, serotonin and 5-hydroxyindoleacetic acid. Serotonin turnover rates were calculated using the specific activities of tryptophan and serotonin at two different time periods. The levels of serotonin as well as the serotonin turnover rates were unaffected by dosages of 5 to 50 mg acrylamide/kg given daily doses, while whole brain concentrations of 5-hydroxyindoleacetic acid increased significantly in a dose-dependent manner. the rise in 5-hydroxyindoleacetic acid levels coupled with no effects on the other levels in acrylamide and 2,5-hexanedione-fed animals suggests a possible inhibition of the energy-dependent 5-hydroxyindoleacetic acid efflux system in the brain. Animals given five doses of Leptophos (4.5 to 45 mg/kg) or six doses from 30 to 300 mg/kg tri-o-tolyl phosphate, administered every third day, showed slightly eleveated, non-significant, serotonin turnover rates while levels of serotonin and tryptophan remained unchanged with a slight decrease in 5-hydroxyindoleacetic acid levels at the highest dosages. Levels of endogenous indole compounds in methylmercury treated rats showed no significant differences from control values; however, the turnover rates and levels of serotonin were slightly lower in the two lower treatment levels, while the highest dose level had no apparent effect on turnover rates or concentrations. Further studies involving longer treatment periods, alternate species or examination of discrete brain areas, may further clarify the effects of these chemicals on brain biochemistry

The Physiology of Growth

The evolution of scientific terminology constitutes an exceedingly interesting subject for study, and may be looked upon as one of the most prevalent growing pains of almost any branch of science. The rapidly developing field of plant physiology is by no means an exception to this; in fact, it furnishes some of the most flagrant examples. A special term is given to a specific quantity, structure, or process, which it is made to fit apparently with great precision. And then as our knowledge extends, we find the name and the scientific entity no longer correspond. The term becomes a misfit, and is used in numerous senses by different authors. Quibbles arise; serious controversies develop largely because one scientist does not have the same concept when he writes one term that the other has when he reads it

The Formation of Root Hairs in Water

In undertaking as a problem for research, the effects of different substances in solution upon the rate of cell enlargement, it was planned to study the development of root hairs in aqueous media, Brink has used pollen tubes in a similar way; and there are numerous studies of the rate of enlargement of multicellular tissues of the higher plants when the latter were supplied with various nutrient or toxic substances. Robbins has used detached roots for his investigations along this line. The root hairs present some advantages in that they are single cells so largely enveloped by external media that it is likely that they are much affected by it, and to a much less extent affected by the substances which come from the remainder of the plant. Furthermore the root hairs of most plants are ordinarily of uniform diameter, so that the increase in length is an index of the increase in cell volume. Finally the measurement of the length of root hairs can be readily and accurately made with the eyepiece micrometer, especially in view of the definite base line which the surface of the root affords

The Diclinous Flowers of Iva ganthiifolia, Nutt

Relatively few of the Compositae have been studied throughout their whole life history. Most investigations have dealt with the varied expressions of a single structure, such as vascular anatomy, style, etc., in various genera of this family. However valuable such research it cannot replace the more intensive study of a single species. Only by this latter method can the different morphological structures be satisfactorily interpreted and relationships established

Optical Communication Systems

A receiver, transmitter, and photon counting detector for use in an optical communication link are disclosed. Also disclosed are methods of communicating using the transmitter, the receiver, and the photon detector

Saddle-point optimality criteria of continuous time programming without differentiability

AbstractSaddle-point optimality criteria of Kuhn-Tucker and Fritz Johns are established in the case of continuous time programming problems. The functions involved are not assumed to be differentiable. In the process, an important theorem of the alternative is also proven

Towed Subsurface Optical Communications Buoy

The innovation allows critical, high-bandwidth submarine communications at speed and depth. This reported innovation is a subsurface optical communications buoy, with active neutral buoyancy and streamlined flow surface veins for depth control. This novel subsurface positioning for the towed communications buoy enables substantial reduction in water-absorption and increased optical transmission by eliminating the intervening water absorption and dispersion, as well as by reducing or eliminating the beam spread and the pulse spreading that is associated with submarine-launched optical beams