Richard Jed Wyatt

An index of the functional condition of rat sciatic nerve based on measurements made from walking tracks

Abstract There is no widely accepted quantitative method for evaluating the functional effects of peripheral nerve damage in animals. In the present study, a method for evaluating sciatic nerve damage was developed from measurements of the prints of the hind feet of walking rats preserved on X-ray film. Four variables were measured from these tracks, and comparisons between the damaged (experimental) and intact (normal) side were converted to percent deficits and averaged to obtain a “sciatic functional index” (SFI). The SFI was then measured under normal conditions, after nerve transection, nerve crush, and sham procedures. Reliability and repeatability of the SFI were found to be excellent. The effects of sciatic nerve transection and nerve crush evaluated by this method agreed very well with other methods of evaluating nerve damage. We conclude that the SFI provides a simple, accurate, reliable, and repeatable method for evaluating the functional condition of sciatic nerve in rats.

Schizophrenia, just the facts. What do we know, how well do we know it?

The basic facts of schizophrenia are subjectively reviewed in terms of their reproducibility and significance for understanding the disorder. Some of the facts that are either less well known or of greater importance for future investigation are discussed in more detail. The purpose of establishing what we know about schizophrenia is to develop firm ground for generating hypotheses. One attempt to synthesize these facts is outlined.

Platelet and plasma amine oxidase activity in 680 normals: Sex and age differences and stability over time

Abstract Platelet and plasma amine oxidase activities in 680 normals exhibited unimodal frequency distributions. Females had 20% higher mean platelet amine oxidase activities, but there were no male-female differences in the plasma enzyme. Age was not significantly correlated with either platelet or plasma amine oxidase activities. The activities of the two enzymes were not significantly intercorrelated. Platelet amine oxidase activity measured with benzylamine as the substrate in a rapid assay based upon platelet counts was highly correlated (r = 0.88) with activity measured in platelet pellets with tryptamine as the substrate. Benzaldehyde and indoleacetaldehyde were identified as the principal products in these assays. Platelet and plasma amine oxidase activities determined three times in the same individuals yielded similar results after approximately 2-week (r = 0.94, 0.97) and 2-month (r = 0.86, 0.84) intervals.

Reduced Monoamine Oxidase Activity in Platelets: A Possible Genetic Marker for Vulnerability to Schizophrenia

Monoamine oxidase activity in blood platelets was measured, with [14C]tryptamine as substrate, in 13 monozygotic twin pairs discordant for schizophrenia and in 23 normal volunteers. The monoamine oxidase activity of both schizophrenic and nonschizophrenic co-twins was significantly lower than it was for the normals, and it was highly correlated between twins. In addition, there was a significant inverse correlation between a measure of the degree of the schizophrenic disorder and the monoamine oxidase activity. These data suggest, but do not prove, that reduced platelet monoamine oxidase activity may provide a genetic marker for vulnerability to schizophrenia.

The flower pot technique of Rapid Eye Movement (REM) sleep deprivation

Abstract This technique of REM sleep deprivation may make data interpretation difficult because it can lack selectivity, and because controls may suppress some REM sleep. To correct these difficulties, EEG recordings were made of rats placed in 4 situations for 96 hours: (1) baseline, (2) on 6.5 cm, or (3) 12.5 cm inverted flowerpots surrounded by water, (4) swimming in 10 cm water for 1 hr per 24 hr. Rats on the 6.5 cm pots had 57% as much REM sleep as baseline with no change in non-REM sleep. Rats on 12.5 cm pots initially had 55% as much REM sleep baseline, but by the fourth day increased to baseline levels. The swimming rats had no reduction in REM or non-REM sleep at any time, and thus seem to be a better control. The smaller the platform relative to the size of the rat, the greater the reduction in REM sleep - but at one point, non-REM sleep is decreased. The combination used here depresses REM sleep by about one half but does not reduce non-REM sleep.

Age-related changes in sleep in depressed and normal subjects

All-night electroencephalographic (EEG) sleep data were examined a function of age in normal control subjects and hospitalized, unmedicated depressed patients with primary affective illness. By analysis of variance, Total Sleep time, Delta Sleep, Sleep Efficiency, Rapid Eye Movement (REM) Sleep, and REM Latency decreased as a function of age, whereas Early Morning Awake time and Intermittent Awake time increased. Compared with normal controls, after the effects of age were covaried out, depressed patients had a greater Sleep Latency, Early Morning Awake time, Intermittent Awake time, Duration and REM Density of the first REM period, and average REM Density for the night, as well as less Sleep Efficiency, less Delta Sleep, and shorter REM Latency, Early Morning Awake time increased with age in depressives but not in normals.

Effects of inhaled beclomethasone dipropionate and alternate-day prednisone on pituitary-adrenal function in children with chronic asthma.

Two corticosteroid regimens, alternate-day prednisone and inhaled beclomethasone dipropionate, have been more acceptable than daily oral corticosteroids for treatment of chronic asthma. To compare the effect of these regimens on hypothalamic-pituitary-adrenal function, 20 children with asthma were evaluated while receiving 20 to 40 mg of prednisone on alternate mornings or 400 to 800 microgram per day of inhaled beclomethasone dipropionate in divided daily doses; seven children requiring only non-corticosteroid medication served as controls. Early-morning serum cortisol concentration, urinary free-cortisol excretion and the 11-desoxycortisol response to metyrapone were decreased to a similar degree among children receiving both corticosteroid regimens in comparison with the control patients and were lowest when alternate-day prednisone and inhaled beclomethasone dipropionate were given together. Thus, inhaled beclomethasone dipropionate appears similar to alternate-day prednisone in its effect on hypothalamic-pituitary-adrenal function when used alone; the effect is additive when the two are used together.

The Na,K-ATPase hypothesis for bipolar illness

A cellular model for bipolar illness is presented. It is propounded that alterations in the activity of the membrane sodium- and potassium-activated adenosine triphosphatase pump (Na,K-ATPase) may be responsible for alterations in neuronal excitability and activity. Specifically, a reduction in Na,K-ATPase activity can lead to both mania and depression by increasing membrane excitability and decreasing neurotransmitter release, respectively. Supporting evidence is reviewed, and clinical and research implications are discussed.

Monoamine oxidase in schizophrenia and other behavioral disorders

Publisher Summary This chapter discusses themonoamine oxidase (MAO) in schizophrenia and other behavioral disorders. Oxidative deamination by MAO represents a major degradative metabolic pathway for such biogenic amines as serotonin, norepinephrine, and dopamine. The concentration of these putative neurotransmitter amines within neurons and othercells is partially regulated by this enzyme. In addition, MAO functions in the intra and extra neuronal deactivation of other amines that accumulate in cells. The enzyme is widely distributed in the body, being present in most human tissues. It occurs in several molecular forms which possessdifferent substrate and inhibitor-related characteristics.

The relationship between changes in REM sleep and clinical improvement in depressed patients treated with amitriptyline

EEG sleep recordings were obtained on consecutive nights from six hospitalized depressed patients before, during, and after treatment with amitriptyline for a total of 370 nights of data, about 85% of all nights of the study. Amitriptyline significantly reduced time spent in rapid eye movement (REM) sleep and prolonged the REM latency throughout the treatment period. Three patients who improved during treatment showed a REM rebound when amitriptyline was discontinued, whereas three patients who did not improve showed no REM rebound.