Rigidity in rats due to radio frequency decerebration and effects of chlorpromazine and mephenesin

Bilateral radio frequency (RF) lesions of the midbrain were produced in an attempt to establish a non-bleeding method of producing decerebrate rigidity in rats. Marked extensor rigidity occurred with a high reproducibility in hindlimbs without the appearance of voluntary movement. Stretch reflex tension induced by repetitive dorsiflexion of the hindfeet was employed as a measure of the intensity of rigidity. Chlorpromazine-HCl (0.1-1 mg/kg, i.v.) and mephenesin (10-50 mg/kg, i.v.) which depress intercollicular decerebrate rigidity, reduced the RF decerebrate rigidity. These results suggest that RF decerebrate rigidity can be used instead of intercollicular transection rigidity in the pharmacological and physiological studies.     

Hyperpolarizing action of enkephalin on neurons in the dorsal motor nucleus of the vagus, in vitro

Intracellular recordings were made from neurons of the dorsomotor vagal nucleus (DMV) in slices of rat medulla oblongata. [D-Ala2, D-Leu5]-enkephalin (DADLE), applied by perfusion (0.01-3 microM) or droplets, dose-dependently hyperpolarized 85% of the DMV neurons tested. The hyperpolarization, associated with a decrease in membrane resistance, persisted after elimination of synaptic activity by perfusion with Ca2(+)-free/high-Mg2+ solution or with 1 microM TTX solution. The opioid antagonist, naloxone, reversibly inhibited DADLE-induced hyperpolarization. The hyperpolarization depended on extracellular K+ concentration and reversed at about -90 mV. DADLE also decreased Ca2(+)-dependent spike duration and after-hyperpolarization (AHP). DAGO (a selective mu-receptor agonist), but not DPLPE (a selective delta-receptor agonist), mimicked DADLE's effects on membrane potential, Ca2(+)-dependent spike duration, and AHP. It is concluded that DADLE, through postsynaptic mu-type opioid receptors, hyperpolarized DMV neurons by increasing K+ conductance, which may have an inhibitory effect on DMV output. DADLE-induced decrease of spike duration and AHP was also mediated by mu-receptors and could have additional effects on functions of the DMV neuron by virtue of reduction in Ca2+ entry.     

Psychiatric patients showing irregular beta activities in EEGs and treatment with antiepileptic drugs: a report of 15 cases

Fifteen psychiatric cases are reported who were clinically diagnosed as schizophrenic, affective disorders, or neurotic, but resisted standard medication regimens, all showing irregular beta activities on EEGs. The cases tended to display symptoms in common, such as dysphoria, emotional instability or frequent physical complaints. These characteristic symptoms share something mutually with the symptoms shown in some epileptic patients or psychiatric patients with epileptic EEG abnormalities without clinical seizures. Antiepileptic drugs seemed more specifically effective to the above symptoms. More than half of these cases showed improvement on EEG findings such as a decrease in irregular beta activities and an increase in rhythmicity or regularity of alpha activities along with clinical improvement with the administration of adjunctive antiepileptic drugs. These results suggest that the adjunctive administration of antiepileptic drugs to patients with irregular beta activities on EEGs is clinically useful and an EEG examination has much value in psychiatric practice to find the criteria of drug therapy.     

Analysis of pleural plaque found at lung cancer screening examination

In the screening test of lung cancer, we found that there was a high prevalence of cases with pleural plaque recognized by chest X-ray film in inhabitants living in A town in Kumamoto Prefecture. We detected abnormal pleural plaque in 148 (41.5%) of 357 cases received lung cancer screening. These pleural plaques resulted in pleural thickening and calcification. Two or three mines of serpentine and an asbestos factory existed in this region from 1883 until 1970. Although twelve cases had a history of factory work, none had fibrous changes in the lung fields on chest X-ray films. It was considered that the pleural plaque probably resulted from exposure to low doses of asbestos in the atmosphere or contact with asbestos workers in their homes. The incidence of lung cancer in this region was not higher than that in other regions in Kumamoto Prefecture. There were no cases of malignant mesothelioma in our hospital during the past eleven years.     

Diagnostic Reliability and Significance of Irregular Beta Patterns

Abstract: We designated EEGs with marked and irregular beta waves in basic patterns as "irregular beta patterns" on the basis that these patterns are related with particular symptoms such as dysphoria, irritability and autonomic symptoms and they implicate choice of therapeutic agents. Because of good response to antiepileptic agents in patients with "irregular beta patterns" along with EEG characteristics, we hypothesized that the prevalence of "irregular beta patterns" is higher in epileptics than in other psychiatric patients. In the present study, we tested this hypothesis, investigating actual frequencies of these patterns among different diagnostic categories for all patients whose EEG were recorded in all the first-visit patients to the Outpatient Clinic, Deparmtent of Neuropsychiatry of the Tokyo University Hospital during one year period of 1986. Before starting this investigation, we checked the interrater reliability for these patterns. Therefore, two studies are reported here. In Study 1, five raters judged 98 EEG recordings blindly (43 epileptics and 55 healthy subjects). As a result, the generalized Kappa of 0.473 was obtained, indicating our agreement level was moderate or fair. This result lends support to our contention that irregular beta patterns are reliably judged. In Study 2, we judged the EEG recordings (137 schizophrenics, 62 affective disorders, 43 epileptics and 55 healthy controls) and calculated the prevalence rate of "irregular beta patterns" among the diagnostic categories. The results show that the prevalence rates of "irregular beta patterns" among psychiatric disorders and normal controls were 13% (18/137) in schizophrenics, 11% (7/62) in affective disorders, 14% (6/43) in epileptics and 4% (2/55) in healthy controls. These rates did not differ significantly among the three disorders. Thus, our hypothesis was not supported. The clinical significance of these patterns is discussed.     

MR imaging of the thymoma--differentiation of invasive thymoma from noninvasive thymoma

Magnetic resonance imaging (MRI) findings were reviewed in nine patients with histologically confirmed thymoma. The morphologic findings obtained by MRI were useful in distinguishing invasive from noninvasive thymoma. Invasive thymomas (2 cases) showed irregular contours and broad obliteration of the fatty plane between the mass and great vessels on T1-weighted coronary images. Perivascular infiltration shadow was considered to be characteristic of invasive thymoma. Noninvasive thymomas (7 cases) were round or oval in shape and showed slight obliteration of the fatty plane. In conclusion, MRI was helpful in differentiating invasive from noninvasive thymoma and defining the extent of thymoma.     

Power spectral analysis of tremor induced by TRH and oxotremorine in mice

Tremor induced by TRH and oxotremorine was recorded by a capacitance transducer, and its intensity and frequency were evaluated using power arrays. In mice treated with TRH (20 mg/kg, i.p.), the latency of tremor was 17.1 +/- 1.7 min (mean +/- S.E.) and the duration was 20.4 +/- 2.2 min, while the frequency was 13.7 +/- 0.3 Hz. In animals with oxotremorine (0.5 mg/kg, i.p.), the latency was 4.3 +/- 0.4 min and the duration was 18 +/- 2.2 min, while the frequency was 12.7 +/- 0.3 Hz. The latter frequency, however, was significantly shifted to a lower frequency as a function of time. In TRH-induced tremor, vertical movements appeared in the same degree as horizontal movements. In oxotremorine-induced tremor, the vertical movements were few, whereas the horizontal movements were observed in a degree similar to those of TRH. The TRH tremor was suppressed by haloperidol and propranolol, but not by atropine. On the contrary, the oxotremorine tremor was inhibited by atropine, but not by haloperidol or propranolol. These results suggest that mechanisms of tremor induced by TRH differ qualitatively from those by oxotremorine; dopaminergic and beta-adrenergic receptor mediated functions may be linked to the developments of tremor caused by TRH, while cholinergic systems have a little effect in mice. The apparatus used in this study and power spectral analysis with power arrays may provide a useful method for simultaneous evaluation of the latency, duration, intensity and frequency of tremors.