Effects of pulmonary exposure to chemically-distinct welding fumes on neuroendocrine markers of toxicity.

Exposure to welding fumes may result in disorders of the pulmonary, cardiovascular, and reproductive systems. Welders are also at a greater risk of developing symptoms similar to those seen in individuals with idiopathic Parkinson's disease. In welders, there are studies that suggest that alterations in circulating prolactin concentrations may be indicative of injury to the dopamine (DA) neurons in the substantia nigra. The goal of these studies was to use an established model of welding particulate exposure to mimic the effects of welding fume inhalation on reproductive functions. Since previous investigators suggested that changes in circulating prolactin may be an early marker of DA neuron injury, movement disorders, and reproductive dysfunction, prolactin, hypothalamic tyrosine hydroxylase (TH) levels (a marker of DA synthesis), and other measures of hypothalamic-pituitary-gonadal (HPG) function were measured after repetitive instillation of welding fume particulates generated by flux core arc-hard surfacing (FCA-HS), manual metal arc-hard surfacing (MMA-HS) or gas metal arc-mild steel (GMA-MS) welding, or manganese chloride (MnCl2). Exposure to welding fume particulate resulted in the accumulation of various metals in the pituitary and testes of rats, along with changes in hypothalamic TH and serum prolactin levels. Exposure to particulates with high concentrations of soluble manganese (Mn) appeared to exert the greatest influence on TH activity levels and serum prolactin concentrations. Thus, circulating prolactin levels may serve as a biomarker for welding fume/Mn-induced neurotoxicity. Other reproductive measures were collected, and these data were consistent with epidemiological findings that prolactin and testosterone may serve as biomarkers of welding particulate induced DA neuron and reproductive dysfunction.

Effects of downhill treadmill running on uncoupling protein 3 mRNA expression.

Eccentric biased exercise has been reported to elicit more muscle injury than concentric or isometric exercise and potentially generate increased oxidative stress one to two days post exercise. Increased oxidative stress has been shown to up-regulate the expression of UCP3 mRNA. The aim of this study was to investigate the effects of downhill running on skeletal muscle UCP3 mRNA expression. Twenty-four male Sprague Dawley rats were randomly assigned to run continuously for 30 minutes (30-C, n = 6), or run six 5-minute bouts separated by rest periods of 2 minutes (2-R, n = 6), 4 minutes (4-R, n = 6), and 6 minutes (6-R, n = 6) on a 16 degree declined treadmill at a speed of 16 m. min (-1). Sham control animals (n = 8) were placed in a treadmill chamber during the 30-minute run session. Semi-quantitative RT-PCR was conducted to evaluate UCP3 mRNA levels in the plantaris, a muscle used eccentrically during downhill running and tibialis anterior, a muscle which undergoes very little eccentric muscle contraction during this exercise. The level of gene expression was normalized to 18 S ribosomal mRNA expression from the same PCR product. Results are reported as mean +/- standard error. UCP3 of the plantaris muscles from 2-R animals (2.36 +/- 0.13) was significantly greater than UCP3 of the plantaris from control animals (1.72 +/- 0.13), p < 0.05. UCP3 of the tibialis anterior from the continuous group (1.51 +/- 0.17) was significantly less than the UCP3 of the tibialis anterior of the control group (2.09 +/- 1.4), p < 0.05. These data suggest that downhill treadmill running is associated with an increase in UCP3 mRNA expression in the plantaris muscle. These results indicate that exercise which is biased toward eccentric exercise may up-regulate UCP3 mRNA during the period post exercise when muscle damage and repair is elevated.

Experimental analysis of human vocal behavior: applications of speech-recognition technology.

Recent developments in speech recognition make it feasible to apply the technology to study vocal behavior. The present study illustrates the use of this technology to establish functional stimulus classes. Eight students were taught to say nonsense words in the presence of arbitrarily assigned sets of symbols consistent with three three-member experimenter-defined stimulus classes. Computer-controlled speech-recognition software was used to record, analyze, and differentially reinforce vocal responses. When the stimulus classes were established, students were taught to say a new nonsense word in the presence of one member of each stimulus class. Transfer of function was tested subsequently to determine if the novel stimulus names transferred to the remaining stimulus class members. Most subjects required two iterations of the training and testing procedures before transfer occurred. The data illustrate the usefulness of recording vocal behavior during stimulus control procedures and demonstrate the use of speech-recognition technology. The paper also describes the current state of speech-recognition technology and suggests several other areas of research that might benefit from using vocal behavior as its primary datum.

Avoidance of 20% carbon dioxide-enriched air with humans.

Four college students were exposed to a Sidman avoidance procedure to determine if an avoidance contingency involving 20% carbon dioxide-enriched air (CO2) would produce and maintain responding. In Phase 1, two conditions (contingent and noncontingent) were conducted each day. These conditions were distinguished by the presence or absence of a blue or green box on a computer screen. In the contingent condition, CO2 presentation were delivered every 3 s unless a subject pulled a plunger. Each plunger pull postponed CO2 presentations for 10 s. In the noncontingent condition, CO2 presentations occurred on the average of every 5 min independent of responding. Following stable responding in Phase 1, condition-correlated stimuli were reversed. In both conditions, plunger response rate was high during the contingent condition and low or zero during the noncontingent condition. Furthermore, subjects avoided most CO2 presentations. However, CO2 presentations did not increase verbal reports of fear. Overall, the results from the present study suggest that CO2 can be used effectively in basic studies of aversive control and in laboratory analogues of response patterns commonly referred to as anxiety.

The use of caffeine versus prophylactic naps in sustained performance.

Previous studies have shown that performance during sleep loss is improved by prophylactic naps as a function of varying nap length. Based on single-dose caffeine studies, a similar dose-response effect has been hypothesized on performance, alertness and mood during sleep loss. The present study compared the effects of repeated versus single-dose administration of caffeine and varying amounts of sleep taken prior to sleep loss on performance, mood and physiological measures during 2 nights and days of sleep loss. A total of 140 normal, young adult males participated at one of two study sites. Ninety-eight subjects at one site were randomly assigned to one of four nap conditions (0, 2, 4 or 8 hours) and 42 subjects at the second site were assigned to one of four caffeine conditions. After a normal baseline night of sleep and morning baseline tests of performance, mood and nap latency, subjects in the nap groups returned to bed at noon, 1600 hours, 1800 hours or not at all. Bedtimes were varied so that all naps ended at 2000 hours. Subjects in the caffeine groups received either a single 400-mg dose of caffeine at 0130 hours each night or repeated doses of 150 or 300 mg every 6 hours starting at 0130 hours on the 1st night of sleep loss. A placebo control group (no nap and placebo administered every 6 hours on the repeated caffeine schedule) was run at both sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Cluster headache following head injury: a case report and review of the literature.

A relation between head trauma and cluster headache is frequently described in the literature. The percentage of cluster patients with a history of head injury is approximately 16.5 when several large studies are reviewed. The present paper reports another case where there is close proximity between head injury and the onset of cluster headache. A review of the literature attempts to document the supposition that there is indeed a causal or precipitous role for head injury in cluster cephalgia pathogenesis.

Self-administration of parenteral ketorolac tromethamine for head pain.

Sixty-one separate self-injections of ketorolac tromethamine (Toradol) by 16 patients diagnosed with episodic migraine with or without aura were evaluated over a 90-day period for safety, efficacy of pain reduction, and the ability of this therapy program to prevent the necessitation of emergency room acute care. Prior to initiation of treatment, patients were formally instructed on intramuscular injection techniques by a member of our nursing staff. Patients were instructed to call upon the onset of a severe headache interfering with daily functioning and, then, were permitted to proceed with the injection. Headache intensity ratings were collected prior to injection and intermittently for the following twenty-four hours. The results demonstrate safety and efficacy of this form of therapy. A significant percent of ketorolac usages (64%) resulted in a good response and significant reduction in head pain. Twenty-three percent of ketorolac usages resulted in a mild response and only 13% of usages provided no relief. Furthermore, 13% of all usages failed to prevent the necessitation for emergency room treatment. The results are discussed in terms of the impact of self-injection on pain relief and substantial cost-reduction by decreasing emergency room utilization.

Phenelzine therapy for headache patients with concomitant depression and anxiety.

Eleven patients with refractory chronic daily headache, associated depression, and generalized anxiety were treated with phenelzine. Ten patients (91%) had a greater than or equal to 50% improvement in headache frequency, seven (64%) had a similar degree of improvement in mood and headache intensity or activity level. Orthostatic hypotension was the most common side effect and necessitated discontinuation of therapy in two patients. One patient suffered a hypertensive crisis which was easily managed and caused no permanent sequelae. Based on these preliminary results, we conclude that phenelzine is effective in the treatment of chronic daily headache with associated depression and anxiety, but further investigations are needed to determine if there is selective efficacy of phenelzine for this subgroup of patients.