The effects of naloxone, morphine and methionine enkephalinamide on Ia afferent terminations in the cat spinal cord

Naloxone, morphine, Met5-enkephalinamide (MENKA) and procaine were administered microelectrophoretically near extracellularly stimulated extensor muscle group Ia afferent fibres and terminations in the lumbar spinal cord of cats anaesthetized with pentobarbitone sodium. Observations were made of effects on the electrical threshold, on the depolarizing action of GABA or piperidine-4-sulphonate (P4S), and on bicuculline-sensitive primary afferent depolarization (PAD) generated by tetanic stimulation of flexor muscle low threshold afferents. All 4 agents reversibly elevated the threshold of Ia fibres in the dorsal column and Ia terminations in the ventral horn. The depolarizations of terminations by GABA or P4S were also reduced, an effect, which for all except MENKA, probably accounted for a concomitant reduction in PAD. In the absence of a consistent effect on either threshold or depolarization by GABAmimetics, MENKA reversibly diminished PAD, an action blocked by naloxone. Intravenously administered naloxone, in doses known to enhance spinal monosynaptic excitation in the cat, had no effect on GABAergic PAD and little or no effect on Ia termination threshold. The results are discussed in relation to a naloxone-sensitive effect of MENKA which reduces transmitter release from GABAergic axo-axonic synapses on Ia terminals, but which does not account for the enhancement of spinal reflexes by naloxone.

The effect of GABA on the terminations of vestibulospinal neurons in the cat spinal cord

Although GABA and piperidine-4-sulphonate depolarize Ia afferent terminations in the lumbar spinal cord by activation of bicuculline-sensitive GABA receptors, no evidence was obtained for a bicuculline-sensitive alteration by either GABAmimetic of the excitability of vestibulospinal terminations. This suggests that the terminal arborizations of vestibulospinal fibers, unlike their cell bodies, are devoid of GABA receptors having properties similar to those on either central neuron cell bodies, primary afferent cell bodies or their central terminations.

Actions of midazolam in the spinal cord of the cat

Midazolam, which induces anaesthesia in humans at intravenous doses of 0.3 mg/kg, did not anaesthetize cats at doses of 20 mg/kg. Nevertheless, intravenous doses as small as 0.3 mg/kg enhanced spinal primary afferent depolarization and presynaptic inhibition of spinal monosynaptic reflexes, and both intravenous and microelectrophoretic administration of midazolam enhanced the inhibitory effect of GABA on spinal neurones and the depolarization of Ia afferent terminations by GABA and piperidine-4-sulphonate. Some degree of specificity was demonstrated for the inhibitory effect of GABA in relation to those of glycine and noradrenaline, and the enhancement by midazolam of inhibition by GABA was blocked by R015-1788, which alone was inactive. Although these results are consistent with proposals that depressant benzodiazepines enhance the effectiveness of GABA as a central transmitter, such an effect alone may not fully account for the anaesthesia produced by midazolam in humans.

Post-excitatory depression of neuronal firing by acidic amino acids and acetylcholine in the cat spinal cord

In the spinal cord of cats anaesthetized with pentobarbitone, the excitation of interneurones and Renshaw cells by acidic amino acids or acetylcholine (Renshaw cells) is followed by a period of depressed excitability. This depression appears to be the consequence of prolonged repetitive firing rather than of the enzymic or chemical conversion of the excitants to neuronal depressants.

Clinico-pathological study of so-called immune zones in leprosy

The clinical, bacteriological and histopathological features were studied in 20 cases of Leprosy (10 LL + 10 BL) from the so-called immune zones i.e. axilla, groin, and a narrow transverse band of skin over the lumbosacral region of the body. Apparently uninvolved skin over the chest was studied as control site. In the so-called immune sites, the clinical lesions of leprosy were noted in 40% of the cases (7 LL + 1 BL), AFB (both solid and granular forms) were detected in the smears of 45% cases (8 LL + 1 BL) and the histopathological evidence of the disease was observed in almost all the sites studied (100%). The results obtained in the present study revealed that practically no area on the surface of skin is immune to leprosy.

Pathological analysis of intracranial tumors

An analysis of 145 intracranial tumors observed in the Department of Pathology, Maulana Azad Medical College, and associated Irwin and G.B. Pant Hospitals was carried out. The relative frequency of the different tumors, their site, and the age and sex of the patients is reported, and compared with previous reports in the literature.

On the condition and activities of Jeddah Endoscopy Center

Present condition and activities of Jeddah Endoscopy Center managed in cooperation with Saudian and Japanese doctors are reported. Total number of patients examined are 1,183 cases; 73% of which were subjected to endoscopy and 27% were to fluoroscopy. With respect to the stomach diseases, gastric cancer and ulcer were found in 16% and 14.7%, respectively. On the other hand, high incidences of severe atrophic gastritis and haemorrhagic or erosive gastritis accounted totally 64.7% of all stomach diseases were noted. Out of 264 cases of duodenal diseases, duodenal ulcer was diagnosed in number of 202 cases (76%). The ratio between gastric and duodenal ulcer was, therefore, approximately 1:6. It was further noted that most of patients with esophagus cancer were found in males having the local habit of taking green tobacco. From the results obtained, discussions were made on the statistical differences of gastrointestinal diseases between Saudi Arabia and Japan.

Leydig-cell tumour of the testis

Leydig cell tumor of the testis is an uncommon occurrence. A case is reported here which had two interesting features. One was extensive calcification and the other an abundant lipid deposition within the tumour cells. The pathogenesis of calcification is discussed.

Imipramine affects autonomic control of sinoatrial rate in isolated right atrial preparations

The effects of imipramine on sinoatrial rate and chronotropic responses to transmural stimulation (TS) were studied in the isolated guinea-pig right atrial preparation. The negative chronotropic response (cholinergically mediated rate decrease) to TS was progressively inhibited by imipramine (5 x 10(-6) M). This inhibition can be attributed directly to an "atropine-like" effect of this drug. The positive chronotropic response (adrenergically mediated rate increase) to TS was markedly potentiated by imipramine at similar therapeutic doses; higher doses (5 x 10(-5) M) substantially depressed this rate response. This depression of the adrenergic response to TS does not appear to be the result of a blockade of beta adrenergic receptors since imipramine still potentiated the rate increase in response to exogenous norepinephrine at doses where no TS response remained. Basal spontaneous rate was also depressed by imipramine at high doses (5 x 10(-5) M), both in the absence and presence of autonomic blockers.

Leprosy of the larynx

Five instances of lepromatous leprosy involving lesions of the larynx were encountered among a series of 280 laryngeal lesions. These are briefly described as involving the epiglottis in all cases, vocal cords in two, and extension into the pyriform fossa in one instance.