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Biomedical subjects

Y Kuroda

Publications and source records attributed to Y Kuroda.

At least 595 records · Page 33Linked to original sources
PubMed1993

Role of vagotony in sinus node dysfunction in children with symptomatic congenital long QT syndrome.

The present study examined chronotropic dysfunction and the role of vagotony in congenital long QT syndrome, sinus node function and the effects of parasympathetic blockade. Six patients with congenital long QT syndrome were studied. The four males and two females, aged 1-15 years, had episodes of syncope and malignant ventricular arrhythmias. Congenital long QT syndrome was defined as a corrected QT interval greater than 0.45 s, T wave alternans and the age at diagnosis. The sinus heart rate measured from a 24 h electrocardiograph was abnormally low (< 50 min) in three patients (1, 4 and 5 years old) and did not increase sufficiently with the administration of atropine in five of the six patients with congenital long QT syndrome. From intracardiac electrophysiological studies, the corrected sinus node recovery time was prolonged in three patients and the total sinoatrial conduction time was prolonged in two patients. In most patients who had an abnormally long sinoatrial conduction time and corrected sinus node recovery time, these values returned to normal following atropine administration. In one patient, the corrected sinus node recovery time was prolonged paradoxically by atropine. Sinus node dysfunction in congenital long QT syndrome was affected by vagotony associated with a right sympathetic nerve system abnormality.

Adolescent↗
PubMed1993

Contribution of pulmonary hemodynamics on manifestation of allergic asthma in patients with congenital heart disease.

The purpose of this study was to determine whether pulmonary hemodynamic abnormalities relate to manifestations of allergic asthma. In 448 patients with congenital heart disease the relationships between asthma and age or pulmonary arterial blood (PA) flow were studied. Asthma (allergic and non-allergic) was more common in 39 (19%) of 201 patients with high PA flow, compared with the incidence in those with normal PA flow (6/117, 5%; P < 0.001) and reduced PA flow (1/130, 1%; P < 0.05). In the high PA flow group, the frequency of asthma declined significantly (P < 0.01) with age, from 25-26% in the 6 month-5 year patient group to 5% in the 6-12 year old patients. The frequency of asthma, including allergic type, was significantly (P < 0.01) greater in patients with pulmonary hypertension (15/24, 63%) than in those without (10/77, 13%) at the age of 6 months to 1 year. Asthma in the high PA flow group was associated with other allergic diseases in 30 (77%) of 39 patients, including food allergy in nine (23%), atopic dermatitis in 14 (36%), allergic rhinitis in seven (18%) and abnormally high total IgE levels in 14 (36%). These findings suggest that high pulmonary flow or pulmonary hypertension enhances the manifestation of allergic disease, particularly asthma.

Asthma↗
PubMed1993

Branch duct origin of solid type pancreatic ductal carcinoma.

A case of branch duct origin of solid type pancreatic ductal carcinoma is presented. Stepwise tissue sections of an entire specimen, including the carcinoma area, and mapping, with special reference to the relationship between the main duct and the carcinoma area, were performed. Carcinoma cells of the branch duct showed intraductal spread with minimal stromal invasion. No carcinoma tissue was observed in the main duct. Therefore this case was considered to be of branch duct origin. The finding of histologically identified branch duct origin of solid type pancreatic ductal carcinoma indicates a distinct advantage to be gained by giving special attention to both the main and branch ducts when using image diagnosis for early detection of carcinomas, and may represent the first reported surgically resected case.

Humans↗
PubMed1993

Pattern-reversal visual evoked potentials in Down's syndrome.

We examined pattern-reversal visual evoked potentials (PRVEPs) in 36 adult patients with Down's syndrome, and analyzed the effects of the ophthalmological abnormalities on results of PRVEPs. The P100 latency was significantly delayed in 24 eyes of 16 patients. The P100 latency was significantly longer and its amplitude was significantly smaller (P < 0.001) in Down's syndrome patients than in age-matched normal controls. In 9 patients without any ophthalmological abnormalities, P100 latency showed no significant difference from that in normal controls, but three of them showed a significant delay of P100. Their P100 amplitudes were significantly smaller than those in normal controls. Therefore, we considered that the ophthalmological abnormalities are one of the main factors causing PRVEPs abnormalities in Down's syndrome patients, but some unknown factors should be also responsible.

Adult↗
PubMed1993

Brainstem involvement in high functioning autistic children.

To determine involvements of the brainstem and/or cerebellum in autism, we compared midsagittal magnetic resonance images of the brains of high functioning autistic children with those of normal controls. We found that the midbrain and medulla oblongata were significantly smaller in these autistic children than in the control children. The pons area did not differ between the two groups, nor was there any difference in the cerebellar vermis area. The ratio of the brain stem and cerebellum to the posterior fossa area did not differ significantly between the high functioning autistic and the control children. A positive correlation between age and area of the cerebellar vermis was observed in autistic children but not in control children. Thus, it was suggested that significant anatomical changes in the midbrain and medulla oblongata existed in the autistic children and that growth of the cerebellar vermis in autistic children was different from normal children.

Adolescent↗
PubMed1993

Effects of movement-related cortical activities on pain-related somatosensory evoked potentials following CO2 laser stimulation in normal subjects.

We investigated the change in pain perception produced by the application of movement and vibration to areas adjacent to, and remote from, the painful stimulus. Pain-related somatosensory evoked potentials (pain SEPs) and the pain threshold were evaluated following CO2 laser stimulation in 17 normal subjects. The concurrent application of vibratory stimuli and the voluntary movement of the fingers of the hand to which the pain stimulus was applied significantly reduced and prolonged the pain SEPs and increased the pain threshold, consistent with the gate control theory. Pain SEPs were also significantly attenuated by voluntary (P < 0.001) and passive (P < 0.02) movement of the remote areas such as the foot, but the pain threshold was unaffected. This finding was not produced by vibration or movement imagery of the limbs without active movement. Therefore, interactions between pain perception and movement-related cortical activities must take place in some areas of the brain without relieving pain.

Adult↗
PubMed1993

Periodic synchronized bursting and intracellular calcium transients elicited by low magnesium in cultured cortical neurons.

1. In Mg(2+)-free external solution, rat cortical neurons in cultured networks entered a stable firing mode, consisting of regular bursts of action potentials superimposed on long-lasting depolarizations. The average separation between bursts varied from culture to culture, but was usually between 5 and 20 s. The distribution of burst intervals followed a Gaussian or normal distribution, with a standard deviation of typically 10% of the average burst period. 2. A gradually depolarizing pacemaker potential was never observed between bursts, but the threshold for action potentials during the quiescent phase was > or = 10 mV above the resting potential. No progressive change in conductance or excitability was observed during the quiescent period. Intracellular stimulation of action potentials did not reproduce the long-lasting depolarization. 3. Switching from current clamp to voltage clamp at the resting potential revealed large postsynaptic currents, mainly excitatory but with a small inhibitory component, at the same phase and frequency as the spike bursts, showing that periodic synaptic input is responsible for the burst-depolarizations. The current could be eliminated by local application of 2-amino-5-phosphonovaleric acid (APV) or 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) to the postsynaptic cell. In the presence of tetrodotoxin, irregular miniature excitatory postsynaptic currents were observed. 4. A fluorescent calcium indicator (fluo-3, 100 microM) was included in the whole-cell pipette solution, to allow simultaneous electrical and calcium measurements in the same cell. In current clamp, transient intracellular calcium increases were found, which were synchronized to the spike bursts. The Ca2+ rise lasted as long as the action potential burst, and was followed by an exponential decay considerably slower than that of the membrane potential. Calcium transients disappeared during voltage clamp at the resting potential, suggesting that calcium influx through voltage-dependent calcium channels greatly exceeds that through synaptic channels. 5. Multisite Ca2+ recording, after loading with fluo-3 acetoxymethyl (AM) ester, revealed that the onsets of burst-related calcium transients were synchronized in all active cells of each view-field, to within approximately 20 ms. Occasionally, secondary rhythms were observed in which only a subset of cells participated. The times to peak and the decay times of calcium transients varied among synchronized cells. 6. The pharmacology of the burst-related calcium transients was investigated by bath application of a variety of compounds.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1993

Brainstem and cerebellar vermis involvement in autistic children.

Recent reports have suggested functional abnormalities of the brain stem in autistic children, and structural abnormalities have also been reported. We obtained magnetic resonance imaging (MRI) scans for 21 autistic children and compared them with 21 control MRI scans. The areas of the brain stem and cerebellar vermis were measured using midsagittal images. The brain stem and cerebellar vermis lobules VIII to X were found to be significantly smaller in autistic children. A positive correlation between the size of the brain stem and cerebellar vermis was observed in the autistic children. This correlation was not observed in the control children. This suggests that the size of the brain stem and cerebellar vermis are anatomically altered in autistic children and that growth of the brain stem and cerebellar vermis in autistic children is different from normal children.

Autistic Disorder↗
PubMed1993

Central nervous system complications after cardiac surgery: a comparison between coronary artery bypass grafting and valve surgery.

Central nervous system (CNS) complications (disturbance of consciousness, focal motor deficits, and seizures) after coronary artery bypass grafting (CABG) and cardiac valve surgery were studied retrospectively. The incidence of CNS complications was significantly more frequent in CABG (11%, 71/638) than in valve surgery (7%, 24/345). Major contributory factors of CNS complications were preexisting cerebrovascular disease and cardiopulmonary bypass time. In comparison to previous reports, older age, hypertension, diabetes mellitus, and cerebrovascular disease were more common in the patients undergoing CABG. The preexisting cerebrovascular disease and prolonged cardiopulmonary bypass time probably increase the risk of cerebral embolism and/or cerebral hypoperfusion. We conclude that patients undergoing CABG surgery are at greater risk for neurological damage in comparison to those undergoing valve surgery.

Aged↗
PubMed1993

Neuroprotective doses of N-methyl-D-aspartate receptor antagonists profoundly reduce the minimum alveolar anesthetic concentration (MAC) for isoflurane in rats.

N-methyl-D-aspartate (NMDA) receptor antagonists, which block one of the glutamate receptors, have provided evidence of cerebral protection in animal models of focal cerebral ischemia. We examined the effect of neuroprotective doses of one noncompetitive (dizocilpine) and two competitive (D-CPP-ene, CGS 19755) NMDA antagonists on the minimum alveolar anesthetic concentration (MAC) of isoflurane in rats. A single bolus injection of any of the three NMDA antagonists produced a significant (P < 0.01) and sustained (> 3 h) decrease in the MAC of isoflurane. Dizocilpine decreased MAC by 33%-38% at a dose of 0.15 mg/kg and 48%-54% at a dose of 0.5 mg/kg. D-CPP-ene decreased MAC by 32%-37% at a dose of 1.5 mg/kg and 39%-45% at a dose of 4.5 mg/kg. CGS 19755 decreased MAC by 19%-24% at a dose of 3 mg/kg and 49%-58% at a dose of 10 mg/kg. Dizocilpine, but not the competitive antagonists, produced a small transient decrease in mean arterial blood pressure. The sustained anesthetic potency of neuroprotective doses of NMDA antagonists supports the idea that glutaminergic receptor activity is involved in determining the anesthetic state.

Anesthesia, Inhalation↗
PubMed1993

"Loose folding" and "delayed oxidation" procedures successfully applied for refolding of fully reduced hen egg white lysozyme.

Several factors and/or procedures were examined quantitatively to improve the refolding yields of hen egg white lysozyme from its fully denatured and reduced state. Firstly, we found that refolding treatments were better conducted at lower lysozyme concentrations. The refolding yield decreased from 70% to less than 5% by increasing the lysozyme concentration from 1 to 36 microM in the refolding solution, probably due to aggregation. Secondly, in order to reduce the aggregation and improve the efficiency of refolding, we applied the "loose folding" procedure which required the incubation in the presence of about 2 M urea. The refolding of the lysozyme, studied at 17.4 microM, increased the yield to 80% yield in the presence of 2 M urea compared with a 30% yield in the absence of urea. Furthermore, we obtained a dramatic refolding yield of more than 95% in an experiment conducted at a concentration of 1.1 microM lysozyme, in the presence of 2 M urea. Finally, we examined the "delayed oxidation" procedure which meant that conformational folding preceded formation of disulfide bonds. The application of this procedure resulted in increases of 5-10% in the refolding yield. These procedures are expected to be useful in improving the refolding yield of precipitated proteins, for example, formed during recombinant DNA protein syntheses.

Animals↗
PubMed1993

Usefulness of the signal-averaged electrocardiogram for evaluating the block site of right bundle branch block following surgical correction of a congenital heart disease.

It is important to distinguish proximal right bundle branch block (RBBB) from distal RBBB because patients with both proximal RBBB and left bundle branch block may progress to a late atrioventricular conduction disturbance. Signal-averaged electrocardiograms (SAECGs) were investigated in 35 patients with RBBB following surgical correction of tetralogy of Fallot or ventricular septal defect in order to determine the block site of RBBB noninvasively using a SAECG. The site of RBBB was first identified by a body surface map; 12 patients had proximal RBBB (group 1), and 23 had distal RBBB (group 2). The control groups consisted of 8 patients with RBBB without congenital heart disease (group 3) and 20 normal subjects (group 4). The mean of the filtered QRS duration in the group 1 patients was significantly longer than in the other 3 groups (p < 0.01). The number of fragmented signals in group 1 was significantly greater than that in the other 3 groups (p < 0.01). A filtered QRS pattern was divided into 4 different types (whole, early, late, and normal) according to the successive fragmented signals; the "whole" type was the most common in group 1 (83%). SAECG is successful in identifying those patients with proximal RBBB according to the following indices: a filtered QRS duration equal to or longer than 160 msec, a fragmented signal number greater than 10 and a "whole" type filtered QRS pattern. In conclusion, SAECG is a useful tool for distinguishing proximal RBBB from distal RBBB.

Bundle-Branch Block↗
PubMed1993

Balloon pulmonary valvuloplasty for infants with severe tetralogy of Fallot.

Balloon pulmonary valvuloplasty was performed in 3 infants with severe tetralogy of Fallot at days 24, 54 and 86 because of progressive hypoxemia. In two patients, the balloon catheter (4 cm long, 5-8 mm diameter) could not pass through the pulmonary valve. This necessitated a smaller balloon and required a two-step procedure. Initially, a coronary artery balloon (2 cm long, 3.5 mm diameter) was used. Following balloon valvuloplasty, arterial oxygen saturation increased from 63 to 83% in case 1, from 69 to 85% in case 2 and 63 to 86% in case 3. Immediate postvalvuloplasty right ventricular cineangiography revealed that the maximal opening diameter of the pulmonary valve leaflets increased from 1-2 mm to 3-4 mm in cases 1 and 3, and from 2-3 mm to 4-5 mm in case 2. No significant complications occurred. Echocardiographic follow-up data showed that the diameter of the right ventricular outflow tract and pulmonary arteries increased with age. The present results show that the pulmonary valvuloplasty is an effective procedure for relief of pulmonary valve stenosis in tetralogy of Fallot and to improve oxygenation and growth of the pulmonary arteries and right ventricular outflow tract without the need of an immediate aortopulmonary shunt.

Cardiac Catheterization↗
PubMed1993

Occurrence of paroxysmal synchronous EEG discharges in subcortical arteriosclerotic encephalopathy (Binswanger's disease).

A 72-year-old patient with von Recklinghausen's disease showed akinetic mutism within 6 months of the onset of dementia. The findings of diffuse cerebral atrophy on CT and periodic synchronous discharges (PSDs) in EEG suggested Creutzfeldt-Jakob disease. However, autopsy findings of diffuse softening of the subcortical white matter and marked arteriosclerotic changes of the subcortical arterioles with sparing of the cortex in the cerebrum confirmed a diagnosis of Binswanger's disease. Binswanger's disease should be included in the differential diagnosis of dementia showing PSDs in EEG.

Aged↗
PubMed1993

Immunochemical detection of advanced glycation end products in lens crystallins from streptozocin-induced diabetic rat.

To reassess the significance of AGEs in cataract formation in diabetic animals, we measured amounts of AGEs in lens crystallins from STZ-induced diabetic animals with a newly developed ELISA. Lenses were removed at 5 and 20 wk after STZ injection. In 20-wk diabetic rats, all lenses were cataractous but not in control rats. In 20-wk diabetic compared with control rats, significant increases were observed in AGEs (172.3 +/- 18.3 vs. 14.3 +/- 1.7 AU, P < 0.01) and fluorescence (2.04 +/- 0.22 vs. 1.27 +/- 0.10 AU, P < 0.05). The amounts of AGEs in lens crystallins, measured by the ELISA, were > 12-fold higher in diabetic rats. In agreement with earlier studies, we found that fluorescence in lens crystallins increased by 61% in diabetic rats. In 5-wk diabetic rats, all lenses were noncataractous. In 5-wk diabetic compared with control rats, significant increases were observed in AGEs (84.1 +/- 7.7 vs. 9.4 +/- 1.5 AU, P < 0.01) and fluorescence (1.45 +/- 0.06 vs. 1.05 +/- 0.06 AU, P < 0.01). Analysis of the AGE content by ELISA showed that accumulation of AGEs in diabetic lens crystallins does markedly occur with time, and a large amount of AGEs exists in the diabetic (cataractous) lens crystallins. The disproportionate elevation of AGEs, measured by the ELISA, compared with fluorescence suggests that the actual levels of AGEs in cataractous lens crystallins from diabetic animals are higher than previously anticipated, and nonfluorescent AGEs may exist in diabetic lens crystallins.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗