Evidence for involvement of the frontal cortex in pain-related cerebral events in cats: increase in local cerebral blood flow by noxious stimuli

Noxious stimuli were shown to induce a remarkable increase in local cerebral blood flow restricted to the forepart of the cerebral hemispheres bilaterally anterior to the posterior sigmoid gyrus in cats. This increase in local cerebral blood flow was averted by lesions in the bilateral ventromedial thalamus and attenuated by pretreatment with an intraventricular injection of 6-hydroxydopamine.

Long lasting suppression of firing of cortical neurons and decrease in cortical blood flow following train pulse stimulation of the locus coeruleus in the cat

Single neuron activity and local cerebral blood flow were recorded simultaneously in the same spot of the gyrus proreus in cats. Train pulse stimulation (10-20 Hz, 30 sec) of the ipsilateral locus coeruleus induced long lasting suppression of firing in up to 78% of neurons and decrease in local flow, which lasted 1.9-5.6 min and 3.8-6.5 min, respectively. Single pulse stimulation evoked inhibition of firing in 55% of the neurons investigated.

Electrophysiological evidence favoring intracaudate axon collaterals of GABAergic caudate output neurons in the cat

Stimulation of the entopeduncular nucleus in the cat was shown to evoke inhibitory responses with a short onset-latency in the caudate nucleus isolated from its afferents. These inhibitory responses are shown to be GABAergic, and some of them are suggested to be monosynaptic in nature.

Tapered fiber-optic sheet formation and its image-guiding properties

Polymer fiber-optic sheets with tapered guides have been made by selective photopolymerization for use as image transformers. A new fabrication technique has been proposed, and good image-guiding properties have been achieved. It has been confirmed theoretically and experimentally that scatterers in cladding layers permit high resolution and surface cladding layers with large refractive-index differences by polymer coating give high lighting efficiency. These tapered fiber-optic sheets used as an image reducer have resolutions of up to 6 lines/mm and lighting efficiency of ~4%.

Primary cerebral malignant lymphoma with macroglobulinemia and carcinoma of the colon

A case of primary cerebral malignant lymphoma, immunoblastic type was reported. The immunoelectrophoresis of the patient serum showed an abnormal bow of IgM lambda type. Autopsy revealed that the cerebral lymphoma showed no extracranial spread except for adenocarcinoma of the colon with hepatic metastasis. Ultrastracturally, some of the lymphoma cells showed plasmacytoid differentiation. Immunoperoxidase study showed intracytoplasmic polyclonal immunoglobulins in non-neoplastic plasma cells around the colonic carcinoma, in the bone marrows, and spleen. However, neither IgM nor lambda light chain was found in the cerebral lymphoma cells. The source of the macroglobulinemia in this case was discussed.

Mediators of slow synaptic potentials in the myenteric plexus of the guinea-pig ileum

1. Intracellular recordings were made from neurones in the myenteric plexus of the ileum isolated from adult guinea-pigs.2. Three synaptic potentials were evoked in different myenteric neurones by focal stimulation of the ganglion surface at a distance of up to 100 mum from the cell body from which the recording was made. These were the fast cholinergic excitatory post-synaptic potential (e.p.s.p.), the slow e.p.s.p. and the slow inhibitory post-synaptic potential (i.p.s.p.).3. 5-hydroxytryptamine and substance P were applied to the neurones by superfusion (10 nm-1 mum) or by electrophoresis within 5 mum of the neurone cell body. 5-HT depolarized, hyperpolarized or had no effect on approximately equal numbers of neurones, whereas substance P depolarized 90% of neurones.4. Many neurones with a depolarizing slow e.p.s.p. were hyperpolarized by superfusion or electrophoretic application of 5-HT.5. Superfusion with 5-HT reversibly depressed the fast e.p.s.p., slow e.p.s.p. and slow i.p.s.p. Superfusion with substance P depressed the slow e.p.s.p.6. Methysergide (10-30 mum) reduced the amplitude of the fast e.p.s.p., the slow e.p.s.p. and the slow i.p.s.p.7. Chymotrypsin (200 mug/ml.) reversibly reduced the amplitude of the slow e.p.s.p., but had no effect on membrane potential, the action potential or the fast e.p.s.p. Chymotrypsin reduced or abolished the depolarization caused by electrophoretic application of substance P, but had no effect on the depolarization or hyperpolarization caused by 5HT.8. The results provide evidence that 5-HT is not the transmitter which mediates the slow e.p.s.p. in myenteric neurones. The slow e.p.s.p. may be caused by substance P or another similar peptide.

Assessment of brainstem damage by the auditory brainstem response in acute severe head injury

In 64 cases suffering from severe head injury (Glasgow coma scale: less than seven- the auditory brainstem responses (FARs) recorded at the vertex, which are thought to be volumet conducted far-field potentials reflecting the sequential electrical activities of the auditory afferen) system in the brainstem, were recorded in the neurosurgical intensive care room immediately after admission. The alterations in the responses were compared with the types of primary injury, neurological signs., CT findings and outcome following treatment. Based on the results obtained, it is concluded that the FAR is a useful indicator for predicting the effects of treatment on brainstem damage in patients with severe head injury, and that it provides more reliable information about the function of the brainstem than the neurological signs or CT findings. Moreover, it also offers a diagnostic method for primary brainstem injury. Three cases or primary brainstem injury without lesions in the supratentorial region were diagnosed by means of combined CT and FAR recording.

Polymer optical circuits for multimode optical fiber systems

Polymer optical waveguides for multimode optical fiber systems have been formed by the selective photopolymerization method, and their waveguiding properties have been investigated. It is shown that the polymer optical waveguides match multimode optical fiber systems, with respect to guide dimensions and index differences, and have a transmission loss sufficiently low for circuit designs in the infrared region (0.19 dB/cm at 0.83 microm). In addition, effective applications of polymer optical circuits to compact optical dividers and lower loss couplers are demonstrated.

Evidence that substance P is a neurotransmitter in the myenteric plexus

Substance P (SP) is an undecapeptide originally isolated from the gut and since shown to occur within neurones in several parts of the peripheral and central nervous systems. Immunohistochemical studies indicate an exceedingly dense network of SP-containing nerves within the myenteric plexus of the guinea pig ileum. These nerves are intrinsic to the gut wall and can release SP to contract the longitudinal muscle layer. We have previously shown that SP directly depolarizes myenteric neurones and that this depolarization has a time course and ionic mechanism similar to the slow excitatory postsynaptic potential (e.p.s.p.) which can be produced by electrical stimulation of presynaptic nerves within the myenteric ganglia. We wondered whether SP might mediate this slow synaptic potential. We report here that the SP depolarization and the slow e.p.s.p. are reversibly depressed by chymotrypsin, an enzyme which degrades SP, although the responses to acetylcholine, serotonin and an unknown hyperpolarizing transmitter are unaffected. The results provide direct evidence that a peptide can mediate chemical transmission between neurones in the mammalian nervous system.

alpha-Guanidinoglutaric acid in cobalt-induced epileptogenic cerebral cortex of cats

Guanidino compounds in the cobalt-induced epileptogenic cerebral cortex of cats were fluorometrically analysed by a JASCO G-520 guanidino compounds analyser, and an unknown high peak was observed in the chromatogram that was identical to the peak of authentic alpha-guanidinoglutaric acid. In another experiment, the substance was extracted from the cobalt focus tissue, converted into dimethylpyrimidyl derivative-butylester, and analysed by a GC/MS technique. The mass spectrum of the substance was identical to the dimethylpyrimidyl derivative of alpha-guanidinoglutaric acid butylester (M+ = 365).

Multiple actions of 5-hydroxytryptamine on myenteric neurones of the guinea-pig ileum

1. Intracellular recordings were made from neurones lying within ganglia isolated from the myenteric plexus of the guinea-pig ileum. 2. 5-hydroxytryptamine (5-HT) (200 nM-10 microM) was applied to 160 neurones by adding it to the perfusing solution. Depolarizations were observed in 27% of neurones, and were more likely to be observed in S-cells. Hyperpolarizations were observed in 30% of neurones, and were more likely to be seen in AH cells. 52% of neurones were unaffected. 2. 5-HT was applied to 104 neurones by micro-electrophoresis from an electrode with its tip placed close to the soma membrane. Depolarizations were observed in 35% of cells, and hyperpolarizations 13%; 10% of neurones showed biphasic responses in membrane potential and the remaining cells were unaffected. 4. The depolarizing responses to 5-HT were associated with an increase in neuronal input resistance and were probably due to inactivation of the membrane potassium conductance. The responses declined in amplitude during prolonged or repeated applications of 5-HT. 5. The hyperpolarizing responses to 5-HT were associated with a fall in neuronal input resistance and were probably due to activation of the membrane potassium conductance. These responses persisted throughout the duration of application of 5-HT and did not show marked tachyphylaxis. The hyperpolarizing responses were reversibly abolished by calcium-free solutions. 6. The depolarizing responses to 5-HT may underlie the release of acetylcholine caused by 5-HT in the guinea-pig ileum. The hyperpolarizing responses may contribute to the inhibition of the peristaltic reflex which has been observed when 5-HT is applied to the serosal aspect of the intestine.

The action of somatostatin on neurones of the myenteric plexus of the guinea-pig ileum

1. Intracellular recordings were made from neurones in ganglia of the myenteric plexus of the guinea-pig ileum. 2. Somatostatin (10-300 nM) was applied to the neurones by adding it to the perfusing solution or by ejecting it (charges up to 500 nC) from an ionophoresis electrode onto the soma membrane. 3. By both methods of application, somatostatin either hyperpolarized or depolarized a proportion of neurones. Depolarizing responses were more often observed with ionophoretic application, and hyperpolarizing responses were more often observed with application by perfusion. Both responses were preserved in solutions containing zero Ca and elevated (6 mM) Mg. Some cells were both hyperpolarized and depolarized, depending on the method of administration. 4. The depolarizing responses to somatostatin were associated with an increase in cell input resistance; they became larger with membrane depolarization and smaller with membrane hyperpolarization, and reversed in polarity at a potential close to the potassium equilibrium potential. The hyperpolarizing responses to somatostatin were accompanied by a fall in cell input resistance.

Changes in local cerebral blood flow and neuronal activity during sensory stimulation in normal and sympathectomized cats

Activities of neurons of the thalamic relay nucleus and cortical somatosensory area which are capable of producing excitatory potentials in response to stimulation of the sciatic nerve were recorded, and local cerebral blood flow was measured simultaneously using a double microelectrode under local anesthesia in both non-pretreated cats and cats undergoing chemical denervation of the vasoadrenergic nerves by intraventricular injection of 6-hydroxydopamine (6-OHDA), in order to unmask the neural control on the cerebral vessels during increase of local metabolic rate. The results obtained may be summarized as follows. (1) A positive correlation was found between an increase in firing rate of a single neuron in the thalamic relay nucleus and somatosensory area and an increase in local cerebral blood flow following stimulation of the sciatic nerve. A distinct spatial and quantitative correlation was thus observed between neural activity and cerebral blood flow. (2) In 6-OHDA-pretreated cats, an increase in neuronal firing rate was observed following stimulation of the sciatic nerve, as it was in non-pretreated cats, but the concurrent response of local cerebral blood flow was seriously impaired. All these findings indicate that the increase in local cerebral blood flow occurring in association with increased neural activity does not result solely from increased local metabolism and a consequent increase in CO2 production, but requires for its occurrence that certain basic conditions be satisfied and maintained by the vasoadrenergic innervation.

Slow synaptic potentials in neurones of the myenteric plexus

1. Intracellular recordings were made in vitro from neurones in the myenteric plexus of the guinea-pig ileum. Potential changes were recorded in response to focal stimulation of the surface of the myenteric ganglion at a distance of 30-100 microM from the impaled cell. 2. Stimuli comprising single pulses evoked cholinergic excitatory post-synaptic potentials ('fast' e.p.s.p.s) in S cells. In a small proportion (20%) of both S and AH cells such stimuli also evoked depolarizing potentials with a time course about 1000 times slower than that of the fast e.p.s.p. 3. Stimuli comprising repeated pulses (up to 20 Hz for 2 sec) evoked the slow depolarizing potentials in a higher proporton of neurones (42%). These stimuli caused a hyperpolarizing potential change in 9% of cells, and in a very few cells biphasic changes i membrane potential were observed. 4. Both the slow depolarizing and the slow hyperpolarizing responses persisted in atropine (up to 5 microM) and hexamethonium (up to 200 microM), but were reversibly abolished by changing to calcium-free solutions. 5. Evidence is presented which suggests that the slow depolarizing response is caused by inactivation of the membrane potassium conductance, and the slow hyperpolarizing response is due to activaton of the potassium conductance.

[Diagnostic value of the far field acoustic response (FAR) as an objective evaluating method for brainstem injury (author's transl)]

Far Field Acoustic Response (FAR) was repeatedly studied from acute stage to chronic stage of severe head injury in 64 patients for evaluation of the degree of brainstem injury. (1) In acute stage within 7 days after trauma, FAR abnormalities are found in 56% of the subjects with severe head injury. These abnormalities are as follows: (i) Prolongation of latency, disappearance of the 5th wave. (ii) Disappearance of the 1st-5th waves or 2nd-5th waves. The incidence of FAR abnormalities is not correlated to disease categories and age of the subjects. (2) FAR findings reveal more precisely the level of brainstem dysfunction than by clinical assessments of brainstem reflexes and posture, and by computerized tomography. (3) Evaluating results of the FAR recorded within 7 days after trauma are correlated to the outcome 3 or more months after injury in the subjects. Almost of them with alteration of only the 5th wave in FAR improve clinically and electrophysiologicaly at 2-3 weeks after trauma. However any patients with disappearance of the 1st-5th waves in FAR are fatal or fell into the state of vegetation. According to these results, it was concluded that FAR has a important diagnostic value as an objective evaluating method for brainstem dysfunction in patients with severe closed head injury.