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Biomedical subjects

K Nakai

Publications and source records attributed to K Nakai.

At least 271 records · Page 15Linked to original sources
PubMed1991

Spatial distribution of late potentials assessed by signal-averaged body surface mapping.

In order to evaluate the spatial location of late potentials (LPs), we designed a new system for the body surface mapping of signal-averaged, filtered ECG using 45 thoracic unipolar leads (5 X 9 array). Signals from patients with old myocardial infarction (MI, N = 8), arrhythmogenic right ventricular dysplasia (N = 1) and dilated cardiomyopathy (N = 2) were amplified and passed through a digital bandpass filter (60-300Hz). Departure maps, LP isopotential maps, and LP30 area maps were generated and superimposed. The LP30 duration was determined as the section between the filtered QRS endpoints and points 30 msec before. Isopotential maps of the LPs showed distinct positive and negative regions. In 8 cases with MI, the extreme was related to the zones indicated by departure maps, and LP30 area maps also corresponded to the departure areas. Most importantly, the spatial distribution for the LP30 area map was different for each type of disease. In conclusion, body surface LP isopotential maps and LP30 area maps may provide useful information concerning the spatial distribution of LPs.

Arrhythmias, Cardiac↗
PubMed1991

Embolization of arteriovenous malformations with peripheral aneurysms using ethylene vinyl alcohol copolymer. Report of three cases.

The authors report three cases of arteriovenous malformations (AVM's) with aneurysms arising from the feeding artery; all were successfully treated with a new nonadhesive liquid embolic material, ethylene vinyl alcohol copolymer (EVAL). In two patients the AVM's were totally removed without difficulty, and in one the AVM was managed conservatively after embolization. No new neurological deficits appeared during or after embolization. After road-mapping techniques, EVAL was injected slowly until the feeding artery and aneurysm were completely obliterated. This embolic agent is easy to handle and is considered safe compared with other adhesive liquid embolic agents, such as isobutyl-2-cyanoacrylate or n-butyl cyanoacrylate. It is concluded that EVAL is an excellent agent for embolizing an AVM with a peripheral aneurysm on the feeding artery.

Adult↗
PubMed1991

[Selective vulnerability of peptide-containing neurons in cerebral ischemia; immunohistochemical study].

Histochemical changes in peptidergic and catecholaminergic neurons during ischemia were investigated in the cerebral neocortex of the gerbil. Catecholaminergic fibers were observed by catecholamine histofluorescence with glyoxylic acid solution, and peptidergic neuron systems such as vasoactive intestinal polypeptide (VIP), somatostatin (SOM), and neuropeptide Y (NPY) were observed by immunohistochemistry. Two hours after unilateral occlusion of the internal carotid artery, catecholaminergic fibers disappeared in the neocortex on the occlusion side, while peptidergic nerve fibers except for NPY fibers were intact after 2 hours of ischemia. NPY fibers had decreased in number on the occlusion side 2 hours after ischemia. VIP-, SOM-, and NPY-immunoreactive neurons showed a decrease of 60% six hours after ischemia, and these neurons completely disappeared in the cerebral neocortex 24 hours after ischemia. These results suggest that catecholaminergic neuron system is more vulnerable than the peptidergic one in ischemic event.

Animals↗
PubMed1991

[Problems of Mason-Likar lead system in treadmill exercise electrocardiography].

A Mason-Likar (M-L) leads system has been widely used in the exercise electrocardiography (ECG) using treadmill for the detection of myocardial ischemia. In routine treadmill exercise ECG using M-L lead, we often observe different patterns of ST-T forms those of II, III and aVF on bipolar leads. In this study, on 213 patients, conventional 12 lead ECG and the M-L lead placement ECG were recorded both at supine and standing positions. A careful analysis was made on all the records of patterns, durations, and amplitudes of QRS and T waves. We also evaluated the ST trendgram of patients with no ischemic changes proven exercise TI-201 myocardial single photon emission tomography (SPECT). Quantitative examination showed no significant differences between those in precordial leads of the standard and the M-L lead system in any subjects. The augmented amplitude of QRS and T waves, the disappearance of abnormal Q-waves in II, III, aVF lead, the negative inversion in QRS phase in lead aVL an left axis deviation were often recognized with M-L lead placement. In treadmill exercise ECG, ST depression more than 1 mm in II, III, aVF lead was noted 14 out of 17 patients with no ischemic changes. The all ST-T changes showed "not-decrescendo" type in ST trendgram. We concluded that rigorous evaluation for electrical axis, the configuration of ST-T waves and the existence of myocardial ischemia in leads II, III, aVF was necessary on treadmill exercise ECG using M-L lead replacement.

Coronary Disease↗
PubMed1991

[A case of recurrent medulloblastoma treated by combination therapy with cisplatinum and tetrahydropyranyladriamycin (PP therapy)].

PP therapy, combination therapy with Cis-platinum (CDDP) and tetrahydropyranyladriamycin (THP-ADR), were performed on a case of recurrent medulloblastoma. CDDP and THP-ADR involve agents difficult to pass the blood brain barrier (BBB), but can pass BBB on the metastatic lesion. PP therapy is considered to be one of the most effective agents for the treatment of recurrent malignant brain tumor.

Adult↗
PubMed1990

Effect of atrial natriuretic peptide on ischaemic brain oedema.

We investigated the effect of intraventricularly administered atrial natriuretic peptide (ANP) on the brain water, sodium and potassium contents in ischaemic brain oedema. Global ischaemia (15 min) followed by recirculation (30 min) produced by a three vessel occlusion in the rat served as a model for induction of ischaemic cerebral oedema. Water content was measured by a drying-weighing method. Sodium and potassium contents were measured by means of flame photometry. The effect of ANP was evaluated by comparing these parameters of the ANP-treated group (5 micrograms/kg and 10 micrograms/kg atriopeptin) with those of the control group (administration of 0.9% NaCL). ANP did not significantly change the content of water, sodium and potassium in the preischaemic or ischaemic brain. Intraventricularly administered ANP (5 micrograms/kg and 10 micrograms/kg) caused significant decrease in the brain water (p less than 0.02) and sodium (p less than 0.01) contents after 15 min of ischaemia and 30 min of recirculation, while the brain potassium content remained unaltered. Serum osmolality, and sodium and potassium concentrations were not influenced by administration of ANP. Accordingly, ANP acts directly on the central nervous system to inhibit brain water and sodium accumulation in ischaemic brain oedema.

Animals↗
PubMed1990

Influence of age on left ventricular performance during exercise in normal Japanese subject: assessment by radionuclide ventriculography.

To assess the effects of age on left ventricular performance, multistage supine ergometer exercise radionuclide ventriculography (RNV) was performed in 92 normal subjects. The subjects ranged in age from 24 to 86 years and were free of cardiopulmonary disease and diabetes. Age-related changes in exercise duration, left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), cardiac output (CO) left ventricular ejection fraction (LVEF), left ventricular dv/dt, systolic and diastolic time indexes of dv/dt, and peak systolic pressure/left ventricular end-systolic volume (PSP/LVESV) were analyzed at rest and during the peak exercise stage. Age-related decrease in LVEDV and peak diastolic dv/dt were significant at rest. The time indexes of ECG R to peak systolic dv/dt and time of end-systole to peak diastolic dv/dt also were prolonged with age. Both maximum heart rate and exercise duration were shown to decline with age. No age-related difference was observed in LVESV, LVEF or PSP/LVESV either at rest or during exercise. However, the change of LVEF and LVESV during exercise was less in subjects aged 60 or more. These results indicate decreased left ventricular function during exercise in elderly subjects.

Adult↗
PubMed1990

Secondary structure of sphingomyelinase from Bacillus cereus.

Of the total of 306 amino acids in the sequence of sphingomyelinase (SMPLC) from Bacillus cereus, almost half (150) are expected to be involved in the formation of loop or turn structure, while 65 and 73 residues may participate in the formation of alpha-helix and beta-structure, respectively. The helix content of SMPLC was calculated to be 0-5%, based on the CD spectra. The addition of divalent metal ions such as Mg2+ or both Ca2+ and Mg2+ had no effect on the CD spectra of SMPLC, although the addition of these metal ions caused the breakdown of membranous SM and specific adsorption of SMPLC onto erythrocyte membranes. A hydropathy study showed that SMPLC has hydrophobic regions at the N-terminal domain which must be responsible for the binding of the enzyme to the membranes. The partial homologies between the amino acid sequences of SMPLC and Clostridium perfringens alpha-toxin (phospholipase C) are discussed.

Amino Acid Sequence↗
PubMed1990

Effect of atrial natriuretic peptide on ischemic brain edema: changes in brain water and electrolytes.

The effects of intraventricularly administered atrial natriuretic peptide (ANP) on the brain water, sodium, and potassium contents in ischemic brain edema were investigated. By use of a three-vessel occlusion model, ischemic brain edema was produced in the rat brain by 15 minutes of global ischemia followed by recirculation. Water content was measured by means of a drying/weighing method; sodium and potassium contents were measured by means of flame photometry. The effects of intraventricular administration of ANP were evaluated by a comparison between the groups given 2 and 5 micrograms of atriopeptin II (treated) and those given 0.9% NaCl (sham-treated). The treated groups showed significant decreases in brain water (P less than 0.02) and sodium (P less than 0.01) contents at 15 and 30 minutes after recirculation, whereas the brain potassium contents remained unaltered. Before ischemia and immediately after 15 minutes of ischemia, intraventricularly administered ANP did not significantly change the brain water, sodium, or potassium contents. There was no significant difference in the effect on the amount of brain water and sodium between the two doses (2 and 5 micrograms). These effects of ANP were thought not to be mediated by primary changes in serum osmolality and sodium and potassium concentrations, because intraventricular administration of ANP did not change them significantly. The present results reveal that, in ischemic brain edema, ANP may act directly on the central nervous system to inhibit brain water and sodium accumulation.

Animals↗
PubMed1990

Effects of an alpha 1-adrenergic blocker (prazosin HCl) on micturition disturbances associated with benign prostatic hypertrophy.

The effects of prazosin HCl treatment on several variables were determined in 16 patients suffering from micturition disturbances associated with benign prostatic hypertrophy. After administration of the drug in doses of 1-2 mg/day, subjective symptoms improved in 11 patients (68.8%). Urine retention rate, maximum urine flow rate, and average urine flow rate exhibited statistically significant improvement, but voided urine volume did not. Urethral pressures declined significantly in the bladder neck and prostatic urethra but not in the pressure at the external sphincter. The results suggest prazosin HCl may be effective in small doses in symptomatic treatment of benign prostatic hypertrophy.

Aged↗
PubMed1990

Detection of the spatial distribution of late potentials by body surface mapping using forty-five unipolar, leads.

For evaluating the spatial location of late potentials (LPs), the authors designed a new system for the body surface mapping of signal-averaged, filtered ECGs using forty-five thoracic unipolar leads (5 x 9 array). The signals from patients with old myocardial infarction (MI, N = 7) and arrhythmogenic right ventricular dysplasia (ARVD, N = 1) were amplified and passed through a bandpass (100-300 Hz) filter. The departure maps, LP isopotential maps, and LP30 area maps were generated and superimposed. The LP30 duration was determined as the section between the filtered QRS endpoints and points thirty milliseconds (ms) before. Isopotential maps of the LPs showed distinct positive and negative regions. In 7 cases with MI, the extreme was related to the zones indicated by the departure maps, and the LP30 area maps also corresponded to the departure areas. In 1 case of ARVD, endocardial fragmented activity directly recorded at the right ventricle closely corresponded with the region on the LP30 area map. In conclusion, body surface LP isopotential maps and LP30 area maps may provide useful information concerning the spatial distribution of endocardial fragmentation.

Arrhythmias, Cardiac↗
PubMed1990

Autologous transplantation of the superior cervical ganglion into the brain of parkinsonian monkeys.

The effect of autologous transplantation of the superior cervical ganglion (SCG) into the brain of parkinsonian monkeys was studied through quantitative measurement of animal behavior. The motor activity of the monkey was measured with a telemetry system during the experiment. After experimental parkinsonism was induced by repeated intravenous injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), three monkeys were treated with autologous transplantation of the SCG into both caudate nuclei. One monkey served as a control without SCG transplantation after MPTP treatment. Three SCG-transplanted monkeys showed biphasic (acute and chronic) behavioral amelioration of parkinsonism after transplantation. In the acute stage, the animals showed transient hyperkinesia with aggressive behavior and loss of circadian rhythm. In the chronic stage following acute hyperkinesia, the animals regained normal behavior and circadian rhythm without aggressiveness. In contrast with the transplanted monkeys, the control monkey failed to show recovery of the bradykinesia and muscle rigidity.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1990

[Nonproducing myeloma without evident bone lesion].

A 76-year-old female was admitted to our hospital because of anemia. Complete blood count was as follows: RBC 2.37 X 10(6)/microliters, Hb 7.7 g/dl, WBC 2,600/microliters, Plt 105 X 10(3)/microliters. A bone marrow aspirate revealed 40.8% plasmacytoid cells showing the characteristics of plasma cells by electron microscopy. Total serum protein was 5.4 g/dl. Monoclonal protein was not observed by electrophoresis. On immunoelectrophoresis, M-bow was not observed in the serum or in 50-fold concentrated urine. The plasma cells were negative for cytoplasmic IgG, M, A, E, D, kappa or lambda by immunoperoxidase studies. Although radiologic studies of the bones did not reveal destructive or punched out lesions, we diagnosed this case as a nonproducing myeloma and the patient responded to MP therapy. This case was considered interesting as regards the pathological entity of myeloma.

Aged↗
PubMed1990

[Relationship between the occurrence of late potential and the location and size of myocardial infarction evaluated by thallium-201 SPECT].

High-frequency, low amplitude signals, late potentials (LPs), in the terminal portion of the body surface QRS of the signal-averaged ECG were frequently observed in ventricular tachycardia (VT) following myocardial infarction (MI). In this study, we evaluated the correlation between the occurrence of LPs and the size and location of MI estimated by Thallium-201 myocardial SPECT in 30 MI patients. The positive LPs were identified by the value of %RMS 40, the percent ratio of the root mean square voltage in the last 40 msec of the QRS complex to that of the total filtered QRS from the signal averaged ECG using bipolar X, Y, Z leads. The spatial distributions of LPs were evaluated by the LP30 area maps obtained by the body surface mapping using forty-five unipolar electrodes. Sixty projections were obtained over 180 degree by rotating gamma camera after 5 minutes intravenous injection of 74 MBq of Thallium-201. After low-pass filtering, images were reconstructed into short-axis, horizontal long-axis and vertical long-axis tomograms. The maximum count circumferential profiles for each short-axis cuts were generated from the apical to basal cut and they were expressed into two-dimensional polar functional maps (apex to the center), Bull's-eye map, to represent myocardial Tl distribution. Normal limits of myocardial Tl distribution were established as the mean minus 2 standard deviation from those of normal subjects. The MI size was estimated as defect volume ratio (DVR), the percent ratio of abnormal region to that of total volume of left ventricle. Significant differences in DVR were observed among MI with LPs and without LPs.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography↗