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Biomedical subjects

N Mikuni

Publications and source records attributed to N Mikuni.

46 records · Page 3Linked to original sources
PubMed1996

Subdural recording of ictal DC shifts in neocortical seizures in humans.

PURPOSE: Invasive ictal EEG recording is often necessary to delineate epileptogenic areas in patients with intractable partial epilepsy, but even intracranial ictal recordings often reveal ill-defined onset zones in neocortical epilepsy. We studied the physiologic significance of ictal direct current (DC) potentials recorded intracranially in human epilepsy. METHODS: We made intracranial ictal EEG recordings in three patients with intractable partial seizures arising from frontal, lateral temporal, and parietal neocortical areas by using closely spaced subdural electrodes (platinum in two patients and stainless steel in one patient) with both standard (1.5 Hz) and open (0.016 Hz) low-frequency filter (LFF) settings. RESULTS: The initial ictal pattern was localized to two to nine subdural electrodes and characterized by very low voltage and high-frequency rhythmic activity ("electrodecremental pattern"). A slow-rising negative potential (DC potential) was seen in a slightly more restricted area (two to six electrodes) and occurred 1-10 s before the initial ictal EEG discharges in two patients. CONCLUSIONS: These results agree with those of previous studies of ictal DC shifts in animals and suggest that ictal DC shifts may be helpful in delineating the epileptogenic area more precisely in human epilepsy.

Adolescent↗
PubMed1995

Limited value of interictal brain perfusion SPECT for detection of epileptic foci: high resolution SPECT studies in comparison with FDG-PET.

Accurate localization of epileptic foci is important for pre-surgical evaluation of patients with medically intractable epilepsy, and F-18 FDG PET has been proved to be a valuable method for this purpose. To examine the clinical value with interictal brain perfusion SPECT, we performed brain perfusion SPECT of Tc-99m HMPAO by means of a high resolution SPECT camera, and compared the results with F-18 FDG PET images and MRI in 10 patients with medically intractable epilepsy. In 9 of 10 patients (90%), FDG PET images showed focal hypo-metabolism in the area corresponding with the results of electroencephalography (EEG). SPECT images, however, demonstrated hypo-perfused lesions which corresponded with hypo-metabolic lesions on FDG PET images in only 6 cases (60%). Although MRI showed abnormal findings in 8 cases, the lesions were not directly related to epileptic foci in 2 cases. In conclusion, FDG PET is a valuable tool for accurate localization of epileptic foci. Brain perfusion SPECT, however, may not always be paralleled to metabolism visualized on FDG PET images.

Adolescent↗
PubMed1994

[Spinal cord stab injury by acupuncture needle: a case report].

It is very rare for neurosurgeons to encounter cases of spinal cord injury caused by a broken acupuncture needle. A 45-year-old man was referred to our clinic because of urinary retention about two weeks after acupuncture therapy (a needle was broken during treatment). The patient showed no motor weakness, or sensory disturbance. The needle was seen transversely stabbing the spinal cord at C1/2 on CT imaging and X-ray film. In all of the reported seven cases of longitudinal stab injuries (posterior puncture), sensorimotor disturbances were present. In transverse stab injuries (lateral puncture), however, two cases did not show motor weakness but sensory disturbance. The centrifugal pathway for micturition in the spinal cord lies in the middle one third of the lateral columns and in the width of the central canal. The patient complained of urinary retention because the bilateral descending fibers might have been stabbed by the needle. Surgical treatment relieved the patient from his complaint.

Acupuncture Therapy↗
PubMed1992

Neurotoxicity of panipenem/betamipron, a new carbapenem, in rabbits: correlation to concentration in central nervous system.

The neurotoxic potential of panipenem/betamipron (PAPM/BP), a new carbapenem antibiotic, was compared with that of imipenem/cilastatin (IPM/CS). The drug concentration in cerebrospinal fluid (CSF) at the onset of epileptogenic electroencephalographic (EEG)-activity and the drug distribution into the central nervous system (CNS) were evaluated. Epileptogenic reactions correlated well with drug levels in CSF, but not with drug levels in circulating plasma. The concentration of PAPM in CSF at the onset of epileptogenic EEG-activity was almost twice that of IPM, suggesting that neurotoxic activity of PAPM is about half that of IPM. In addition, in terms of incidence percent for the epileptogenic EEG-activity, PAPM/BP was found to be less toxic than IPM/CS within the dose of 1.0-1.2 g/kg. Concentrations of PAPM in CSF and brain extracellular fluid after PAPM/BP i.v. infusion were comparable with those of IPM after IPM/CS infusion, indicating the similar characteristics of distribution into the CNS for the two antibiotics. From these results of pharmacologic effects and drug distributions, it is suggested that the neurotoxicity of PAPM/BP is less than half that of IPM/CS.

Alanine↗
PubMed1980

EEG change in the conscious rat during immobility induced by psychological stress.

EEG changes in the conscious rat under conditions of stress were quantitatively analyzed. After conditioning the rat to expect an electroshock when placed in the test box, the rat assumed a catatonia-like immobility when placed in the box even though the electroshock was not applied. While in this state relative brain-wave activity over the range 7.5--13.0 Hz significantly increased in the cortex and the hippocampus, but not in the amygdaloid and the caudate nuclei. The immobility accompanied by changes in the EEG disappeared when the animal was returned to the home cage and immediately reappeared after the rat was retransferred to the test box. Diazepam (10 mg/kg, PO), CS-386 (5 mg/kg, PO), nicotinamide (1 mg/kg, IP), and chlorpromazine (10 mg/kg, PO) significantly suppressed the augmented activity under the same stress condition. The difference between drug-induced catatonia or catalepsy and the catatonia-like immobility under the stress condition was discussed.

Animals↗
PubMed1978

[Effects of a vitamin B complex on functional recovery after nerve injury (author's transl)].

Functional recovery after nerve crushing was investigated in the following manner: Under pentobarbital anesthesia the sciatic nerve of the rat was crushed at the level of the hip (proximal crush) or the thigh (distal crush). The recovery processes after the nerve crushing were followed by measuring distances between the first and fifth digits(DBD.1 approximately 5) and between the second and fourth digits (DBD.2 approximately 4) of the hind paw, and by observing changes in "behavior" scored on a scale of 10 according to the degree of behavioral disorder of the hind paw and leg. Results obtained by these methods showed good reproducibility. The DBD values and the scores for behavior recovered significantly faster after weak nerve crushing than after strong crushing, and after distal rather than after proximal crushing. When a segment of the sciatic nerve was resected, there was no recovery. These results suggest that DBD.1 approximately 5, DBD.2 approximately 4, and the behavior observed in these experiments serve as good indices for evaluating the degree of functional recovery after nerve injury in unanesthetized and unrestrained animals. Effects of a preparation of vitamins B1, B6, and B12 (B complex) on these three parameters and on weights of 9 muscles of the hind leg were also studied. These studies showed that the B complex facilitated functional recovery from nerve injury faster than its components, and that on muscle atrophy the B complex had its most effects on the soleus. It was also shown that B1 and B12 by themselves had significant facilitating effects on the functional recovery.

Animals↗
PubMed1978

[Effects of a new psychotropic agent, CS-430, on the central nervous system of experimental animals (author's transl)].

In rats and rabbits with chronically implanted electrodes CS-430(10-bromo-2, 3, 7, 11b-tetrahydro--11b-(2-fluorophenyl)-oxazolo(3, 2d) [1, 4]benzodiazepine-6(5H)-one) (3 mg/kg, .o.) decreased the slightly awake period and increased the slow-wave sleep period. The onset time of sleep was significantly shortened. In the rat pre-treated with p-chlorophenylalaine (500 mg/kg, p.o.), the awake period was remarkable increased and the slow wave sleep period was considerably decreased at 48 hours after the pre-treatment. In these rats CS-430 given in the same dose decreased significantly the awake peiod and the onset time of sleep and increased the slow wave sleep period. CS-430 raised the threshold of the arousal response with stimulation of the posterior hypothalamus, but not of the mesencephalic reticular formation. These effects of CS-430 were almost as potent as those of nitrazepam (NZP). CS-430 reduced duration of after-discharges following stimulation of the hippocampus, depressed the decerebrate rigidity and inhibited activity of lumbar gamma-motoneurons in anesthetized cats. CS-430 (10 mg/kg, p.o.) inhibited the evoked responses recorded from the proreus gyrus following stimulation of either the baso-magnocellularis of the amygdaloid nuclear or the ventral hippocampus, although such did not inhibit the responses between the olfactory bulb and the pyriform cortex, the thalamus and the sensory-motor cortex. Thus CS-430 has a sleep-inducing effect in animals of almost the same potency as is seen with NZP, and site(s) of the action in the limbic system appear to be specific.

Amygdala↗