Ultrasonic effects on electroorganic processes. Part 17. Product selectivity control in cathodic reduction of acrylonitrile

Product selectivity for adiponitrile, which was formed as the corresponding hydrodimeric product along with propionitrile as the hydromonomeric product in the cathodic reduction of acrylonitrile, was significantly increased under ultrasonic irradiation with an intensity above the ultrasonic cavitation threshold. This ultrasonic effect is rationalized as due to mass transport promotion of acrylonitrile molecules to the cathode surface from the bulk electrolytic solution by high speed jet streams caused by the cavitation. A mechanism for the ultrasonic effect is discussed in detail on the basis of the reaction pathway of the hydrodimerization of acrylonitrile.

Neuronal injury in experimental status epilepticus in the rat: role of acidosis.

Systemic and cerebral acidosis accompanies generalized tonic-clonic seizures and status epilepticus. Acidosis during status may be modified by neuromuscular paralysis, intubation and ventilation, or administration of a base, but the effect of acidosis on neuronal injury from status is uncertain. We studied the effect of acidosis, induced by hypercarbic ventilation, on heat-shock protein (HSP72) induction in rat brain as a measure of neuronal injury in experimental status epilepticus. Acidosis was found to attenuate neuronal injury, independent of its anticonvulsant effect.

Neuronal injury in experimental status epilepticus in the rat: role of hypoxia.

While it seems axiomatic that hypoxia is a risk factor for neuronal death during prolonged seizures, the classic neuropathologic literature does not confirm such an association. We investigated this issue by inducing status epilepticus in normoxic (PaO2 approximately 100 mmHg) and hypoxia (PaO2 approximately 50 mmHg) rats, using heat-shock protein (HSP) expression as an index of early cell injury and acid fuchsin staining to detect cell death. Neither stress protein induction nor neuronal death was increased in the selectively vulnerable CA3c region of hippocampus, or in cerebral cortex, of hypoxic compared to normoxic animals. These data support the concept that moderate hypoxia is not a risk factor for brain injury from status epilepticus.

Functional magnetic resonance imaging of the human motor cortex.

Functional magnetic resonance (MR) imaging of the brain was performed during motor task activation in five normal subjects and a patient with meningioma using conventional fast low-angle shot sequences and a 2.0 T system. A high intensity area in the motor cortex was observed in all normal subjects. Single-slice studies showed the right-sided finger task produced an increase of 1.9-23.5% (6.67 +/- 4.36%) in the signal intensity of the left motor cortex, while the left-sided finger task increased the signal by 1.5-18.2% (6.09 +/- 3.34%) in the right motor cortex. There was no significant difference between the sides. Multiple-slice studies also showed the activated motor cortex as a high intensity area. The maximum signal intensity increase in the activated motor area was 11.0% for the left motor cortex and 8.8% for the right motor cortex. There was no significant difference between the sides. Preoperative mapping of the patient with meningioma showed that the motor cortex was displaced posteriorly by the tumor. Functional MR imaging is possible with a standard MR imaging system and conventional gradient echo sequences. Useful clinical information can be obtained by preoperative mapping of the motor cortex.

Epileptic tolerance: prior seizures protect against seizure-induced neuronal injury.

Heat shock proteins (HSPs) are induced by a variety of insults to the nervous system, including seizures, and may be neuroprotective. If this is so, prior induction of HSPs should decrease neuronal damage upon re-exposure to an injurious stimulus. To test this hypothesis in relation to seizures, bicuculline was given to rats in two sessions, separated by 1, 3, 5 or 7 days; seizure activity was recorded, and HSP-like immunoreactivity and neuronal injury (acid-fuchsin staining) were quantified in the CA3c sector of the hippocampus. Prior seizures conferred a time-dependent protective effect against hippocampal injury induced by subsequent seizures, which may represent 'epileptic tolerance', analogous to the previously described phenomenon of 'ischemic tolerance'.

Early detection of cerebral infarction by 31P spectroscopic imaging.

Recent advances in magnetic resonance spectroscopy permit noninvasive study of brain metabolism in vivo, 31P spectroscopic imaging being the method for evaluation of localized phosphorous metabolism. Experimentally, an ischemic-hypoxic brain insult is characterized by depletion of high energy metabolites. These changes are seen immediately after an ischemic insult. We had the opportunity of carrying out 31P spectroscopic imaging of hyperacute cerebral infarction, while MRI and CT were negative. Cerebral infarction of the middle cerebral artery territory was suggested by 31P spectroscopic imaging, which was closely consistent with a later-developing region of low density on CT. In cerebral infarction, early detection of the lesion is a useful pointer to the patient's prognosis, making 31P spectroscopic imaging a potential tool.

Magnetic resonance study of brain oedema induced by cold injury--changes in relaxation times before and after the administration of glycerol.

Experiments were carried out to determine the ability of magnetic resonance systems to assess change in relaxation times following the induction of experimental brain oedema and subsequent administration of hypertonic glycerol. Nine small mongrel dogs were used for these experiments. Twenty-four hours after producing a cold lesion, magnetic resonance (MR) studies were performed and physiological data were measured. Thirty min after beginning the administration of glycerol, serum osmotic pressure was raised 88 mOsm/l. After administering glycerol a small reduction in long spin echo images was observed in the periventricular high intensity area. The T1 and T2 values appeared to be decreased from 30 min after glycerol administration. This decrease continued until the period of observation ended. Statistically significant changes in the T2 values, especially in the white matter of the opposite side, were seen. The changes in T1 were generally not statistically significant. We conclude that the changes in water content of the oedematous brain following the administration of glycerol can be detected by magnetic resonance systems, that these changes become appreciable 30 min after administration of glycerol and continue at least two more hours, and that the changes in T2 were larger than those in T1.

Magnetic resonance studies in human brain oedema following administration of hyperosmotic agents. Special references to relaxation times and proton MRS.

Changes of proton relaxation times (T1 and T2) and proton Magnetic Resonance Spectroscopy (MRS) were studied in patients with brain oedema following administration of hyperosmotic agents. Relaxation times of oedema tended to decrease following infusion of hyperosmotic agents. In most patients examined, changes of relaxation times tended to achieve their lowest value at 30-60 minutes after infusion. However, the changes of relaxation times were not uniform. In some patients, relaxation times continued to decrease for more than 2 hours, while in other patients relaxation times which had earlier decreased subsequently had increased at 2 hours. The peak of water components, obtained by SIDAC (Spectroscopic Imaging by Dephasing Amplitude Changing) method was observed to change as did relaxation times. Changes of relaxation times and the peak of water components, obtained by SIDAC (Spectroscopic Imaging by Dephasing Amplitude Changing) method was observed to change as did relaxation times. Changes of relaxation times and the peak of water component may vary depending upon factors including the kinds of lesions causing oedema, phase of oedema (acute or chronic), etc. Proton relaxation times and the peak of water component obtained by proton MRS were useful in evaluating the changes of oedematous area.

[A case of intracranial chordoma with a special reference to the findings in computed tomography (author's transl)].

A case of chordoma was reported with a special reference to the computed tomography. A 22-year-old female, who had been in good health, was admitted to Kagoshima University Hospital on December 8, 1978 with a chief complaint of diplopia. Physical examination was nothing particular and neurologic examination revealed the left abducent nerve palsy. The labolatory findings including blood count, serum electrolytes, hormonal study, carcinoembrynonic antigen (CEA) and alpha-fetoprotein were within normal limits. Plain skull filsm showed a retro-sellar calcification in combination with a bony erosion of the dorsum sellae and the clivus. The left vertebral arteriography and the left carotid arteriography showed a space taking lesion extended from the retro-clival to the left parasellar region. The axial CT scanning showed a round and irregular high density area consistent with calcification, at the retro-clival area, middle cranial fossa, and parasellar region in the left side, and no enhancement effect was acquired. The coronal CT appearance showed a round but discontinuous high density area like a coral reef, based on the clivus. These CT findings indicated the extension of the space taking legion, clearly. Intra-capsular removal of the tumor was performed and histologic examination confirmed the chordoma. It will be emphasized that CT scan, particularly coronal section was one of the most useful diagnostic procedure of amss of the skull base.