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Biomedical subjects

H Noda

Publications and source records attributed to H Noda.

At least 235 records · Page 13Linked to original sources
PubMed1989

Adherence of oral streptococci to composite resin restorative materials.

The frequency of oral streptococcal bacterial isolates detected on composite resin squares attached to maxillary first molars in 12 volunteers was 62.1 per cent. These cocci consisted of Streptococcus mitior (52.8 per cent), S. sanguis (20.2 per cent), S. oralis (8.6 per cent), S. salivarius (1.0 per cent) and S. anginosus (0.3 per cent). An electron microscopic study of these organisms labelled with [3H]thymidine for in vitro adhesiveness to the resin revealed that S. mitior was the most adhesive, and that its pronounced adhesiveness is associated with its characteristic extracellular ultrastructure.

Bacterial Adhesion↗
PubMed1989

Norepinephrine responsiveness in patients with borderline hypertension under three different sodium balances.

The pressor effects of intravenous norepinephrine (NE) infusion (100 and 200 ng/kg/min for 15 min) were examined in 17 patients with borderline hypertension (BHT) and 15 age-matched normotensive subjects (NT) under three different sodium balances; the regular customary diet, treatment with diuretics, and the high-sodium diet. Treatment with diuretics decreased and high sodium diet increased the pressor response to NE in both groups but there were no significant differences in NE reactivity between the groups. The increments in mean blood pressure after NE infusion (200 ng/kg/min) during the three experimental periods correlated significantly with the preinfusion plasma NE concentration in both BHT and NT: r = -0.58 (p less than 0.01) and r = -0.54 (p less than 0.01), respectively. Neither the slopes nor the intercepts differed between the two groups. Thus, evidence presented indicates that BHT do not have increased pressor responsiveness to NE, and that NE pressor response depends upon basal sympathetic tone.

Adult↗
PubMed1989

Effects of the yeast extract components pyrroloquinoline quinone and aspartic acid on vitamin B12 production in Klebsiella pneumoniae IFO 13541.

The production of vitamin B12 from carbohydrates, peptone, casamino acid, etc., by intestinal bacteria was investigated. Klebsiella pneumoniae IFO 13541 was the most efficient strain for vitamin B12 production, which depended exclusively on the concentration of yeast extract added to the medium. A concentrated solution of yeast extract (1 ml) was chromatographed on a Sephadex G-25 column (1 x 180 cm) and eluted with H2O (eighty fractions of 3 ml each were collected). It was found that fractions in which bacterial growth was most prevalent also exhibited the highest amount of vitamin production. The effectiveness of yeast extract was shown by the participation of pyrroloquinoline quinone and aspartic acid in the growth stimulation and in the vitamin B12 production in this strain.

Acetobacter↗
PubMed1989

[Comparative study of the protective effects of a cold potassium cardioplegic solution verses the Collins solution in the preservation of canine hearts for 24 hours by simple immersion method].

This study was undertaken to compare the protective effects of a cold potassium cardioplegic solution (K+:23 mEq/l, Na+:25.2 mEq/l) versus the Collins solution (K+:115 mEq/l, Na+:10 mEq/l) on the preservation of isolated canine hearts for 24 hours by simple immersion. To assess the viability of the preserved hearts, recovery of left ventricular function, myocardial water content and myocardial ultrastructures were evaluated before and after preservation. Isovolumic left ventricular function was evaluated with an intra-ventricular balloon method using a preparation of an isolated, blood-perfused heart. The cardioplegic solution group (n = 9) showed significantly better recovery results of pressure developed in the left ventricular (84-76 vs. 35-37%) and dp/dt (90-52% vs. 44-39%) as compared to the Collins solution group (n = 13). Compliance of the left ventricle was well maintained in the cardioplegic solution group. The Collins solution group showed a significant increase of myocardial water content and a remarkable decrease in compliance of the left ventricle after preservation. The quantitative evaluation results of the mitochondrial injury (mitochondria score) found through electron microscopy revealed that the mitochondria of the cardioplegic solution group were less injured as compared to those of the Collins solution group. We concluded that our cold potassium cardioplegic solution offers superior protective effects on the preservation of the heart by simple immersion as compared to the Collins solution.

Animals↗
PubMed1989

[Development and evaluation of ventricular assist blood pump to salvage patients with profound heart failure].

One of the most important characteristics of a ventricular assist device (VAD) is good antithrombogenicity such that the circulating blood does not clot on the surface even when the bypass flow through the device is reduced at the time of weaning-off. A pneumatic and diaphragm-type VAD with excellent antithrombogenicity was developed for clinical use. The pump is made of Japanese-made segmented polyether polyurethane and the maximum output is 7.0 L/min. If the bypass flow was maintained above 2.0 L/min during early postoperative period, thrombus formation was rarely observed even when the flow rate decreased afterwards in chronic animal experiments using 30 goats. Experimental analyses suggested that a biolization mechanism of the material surface covered by absorbed plasma protein might play a major role in the establishment of antithrombogenicity of the pump. No mechanical failure, thrombosis, calcification, and complication in experimental animals occurred when the VAD manufactured under our good quality control system was driven adequately. These results proved that the VAD could be used reliably for at least 3 months. In conclusion, the VAD is safely applicable to clinical cases and contributes to treatments of profound heart failure patients.

Acute Disease↗
PubMed1989

[Early operation for postinfarction ventricular septal perforation; report of three cases].

Three patients underwent surgery for postmyocardial infarction ventricular septal perforation (VSP) within 3 to 21 days after onset of infarction. The hemodynamic stabilization was not obtained despite aggressive medical treatment including Intra-aortic Balloon Pumping (IABP) in one patient. The others had sudden hemodynamic deterioration during IABP support. In two of the three cases, the VSP were closed via transinfarct ventriculotomy with double Dacron patch, and ventricular wall reconstruction was performed to sandwich the double septal patch between ventricular free walls with Dacron felt strips. Two of the three patients survived. Our experience suggests that early surgical intervention is essential unless medical therapy results in clinical improvement and the double patch method may provide a successful operative repair and comeout.

Adult↗
PubMed1989

[Experimental studies of prolonged circulatory maintenance with a left ventricular assistance in cardiac arrested goats].

Recently, various types of left ventricular assist systems (LVAS) have become available to treat the patients in profound heart failures beyond the limit of the effects of IABP. However, the occurrence of an intractable severe bi-ventricular failure, ventricular fibrillation (VF) or cardiac arrest during the time with left ventricular assistance became a more serious problem. Since during the usage of these assist devices, pulmonary venous return will decrease, consequently, LVAS will not be able to maintain sufficient systemic circulation over a extended duration. This study was intended to develop a method of prolonged circulatory maintenance only with a LVAS in cardiac arrested goats until the time when heart transplantation will be performed. In this study, our LVAS was implanted between the left atrium and the aorta in twelve goats in which the hearts were fibrillated. We have followed the principle of circulatory maintenance only with our LVAS in cardiac arrest based on the pressure gradient between the right and left atria and at the same time the pump suction effect through the lungs. The results showed that when pulmonary vascular resistances (PVRs) were kept within normal ranges (less than 15,000 dynes.sec.cm-5), systemic circulations were well maintained only with LVAS as long as RAPs were kept in 14-18 mmHg. Under these conditions, the systemic circulatory flows have fluctuated between 80-140 ml/kg/min depending on the animals demands. The mean arterial pressures were kept above 80 mmHg and the goats have shown quite normal behaviors. However, in goats which showed the presence of pleural effusions and ascites were found to be more difficult to maintain prolonged normal circulation. In our study, the maintenance of total serum protein level above 6.0 g/dl was found to be essential to prevent the development of both pleural effusions and ascites . The authors have achieved the longest survival goat for a duration of 38 days after implantation with our LVAS. We have concluded that when PVRs may be kept in normal ranges, our LVAS can maintain normal systemic circulation even in arrested hearts for a prolonged duration during which time heart transplantation or total artificial heart replacement can be performed.

Animals↗
PubMed1989

Prerequisites to salvage profound biventricular failure patients with ventricular assist devices.

We conducted chronic experiments to determine how to treat profound biventricular failure systematically with ventricular assist devices (VADs) and to analyze the factors that affect prognoses for this condition. Anoxic arrest was induced in ten goats by aortic cross-clamping under normothermic conditions (38.5 degrees C) for 30 (n = 3), 45 (n = 1), and 60 (n = 6) minutes. A left ventricular assist device (LVAD) was implanted in eight animals, and a biventricular assist device (BVAD) was used in two. Three goats--two of which had undergone anoxic arrest for 30 minutes and one for 60 minutes--whose right atrial pressure (RAP) was approximately 18 mm Hg during the acute stage, recovered in two to three weeks, and the pumps were successfully removed. Pathological findings in these animals showed scattered areas of surviving myocardium, with connective tissue replacing the degenerated myocardium. The remaining five LVAD goats required higher RAPs to maintain circulation and died from various causes. Maintaining circulation without volume loading, even in the presence of arrhythmias, was easier with the BVAD. One BVAD animal that underwent 45 minutes of anoxic arrest recovered from right ventricular failure, and the right pump was removed. The second goat (anoxic arrest, 60 min) on the BVAD failed to recover. Autopsy of the myocardium revealed a thin ventricular wall. Our studies show that the use of VADs allows time for a failing heart to recover, but the potential for healing is affected by the severity of myocardial damage prior to VAD application.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Treatment of acute myocardial infarction with cardiogenic shock using left ventricular assist device.

We have treated ten cardiogenic shock patients after acute myocardial infarction (AMI) with a left ventricular assist device (LVAD). These patients were later divided into three groups: the first group with ventricular septal perforation, the second with aorto-coronary bypass grafting (ACBG) before LVAD implantation and the third group without ACBG. LVAD maintained the systemic circulation in each group, and cardiac function recovered enough to remove LVAD in 70% of the total patients. Two of three patients in the first group were discharged from hospital. Two weaned cases in the second group died of multiple organ failure and one was discharged, and hemorrhagic necrosis was seen in the bypassed area of the myocardium. One patient of the third group could not be weaned from LVAD because of respiratory failure though his heart function began to recover. Another case in the third group underwent bypass grafting after removal of LVAD. However ACBG surgery should be done very carefully because a patient in shock is occasionally intolerant to major surgery. In all groups, the major cause of death was multiple organ failure which was probably caused by the prolonged low output condition prior to LVAD application. In the light of this experience, it appears that LVAD should be applied before irreversible damage occurs to major organs, including the heart itself. To ensure the timely application of LVAD, some way must be found to introduce systematic application of LVAD into the normal course of AMI treatment.

Aged↗
PubMed1989

Determination of infarct size of acute myocardial infarction in dogs by magnetic resonance imaging and gadolinium-DTPA: comparison with indium-111 antimyosin imaging.

Acute myocardial infarctions were produced in nine dogs by ligation of the left anterior descending coronary artery. Twenty-four hours after ligation, 0.5 mM/kg of gadolinium (Gd)-DTPA was injected intravenously, followed by cardiectomy 30 min later. Indium-111 antimyosin was administered intravenously 6 hr before cardiectomy to compare the infarct size with Gd-DTPA contrast enhancement. Areas of Gd-DTPA contrast enhancement were closely correlated with those of indium-111 antimyosin uptake (r = .86), although the former showed slightly greater than the latter. Partial and complete enhancements were observed in three and six dogs, respectively. In the T1 and T2 maps, T1 relaxation times of the infarcted area showed greater T1 shortening compared with normal myocardium, whereas T2 relaxation times were not different between infarcted and normal myocardium. Thus, Gd-DTPA showed significant contrast enhancement of the infarcted area because of greater T1 shortening and the extent of Gd-DTPA contrast enhancement expressed the infarct size precisely.

Animals↗
PubMed1988

Hydrazine radical formation catalyzed by rat microsomal NADPH-cytochrome P-450 reductase.

Using NADPH-cytochrome P-450 reductase purified from rat liver microsomes, the oxidation of hydrazine to its radical was proved to proceed smoothly. The catalytic effect of NADPH cytochrome P-450 on the radical formation in the hepatic microsomes obtained from phenobarbital-pretreated rats was also supported by the fact that Hz radical formation was stimulated by flavin adenin dinucleotide or methyl viologen and markedly inhibited by superoxide dismutase, however, carbon monoxide showed no effect. Expectedly, anti-NADPH-cytochrome P-450 IgG decreased the radical formation. The present study provides the first evidence for the NADPH-cytochrome P-450 reductase catalyzed oxidation of hydrazine to its radical in the presence of O2 and NADPH.

Animals↗
PubMed1988

Continuous measurement of oxygen delivery and oxygen consumption in awake live animals.

For continuous measurement of both SO2 and [Hb] of whole blood, a hybrid type optical sensor was developed, tested in vitro and applied to the continuous measurement of arterial and mixed venous SO2 and [Hb] of awake live animals whose circulation was entirely supported by a pair of artificial hearts. The purpose of using artificial hearts was to control the cardiac function precisely and to obtain independent responses of the peripheral circulatory system. Both sensors in the arterial and venous circuits functioned satisfactorily for a duration of 40 days; no blood clots were observed around the sensor and the mixed venous SO2 varied sensitively in response to changes in the respiratory status, pump output, [Hb], and oxygen consumption, thus showing that it could be used as an indicator to evaluate the adequacy of oxygen delivery to peripheral tissues.

Animals↗
PubMed1988

Effect of drive mode of left ventricular assist device on the left ventricular mechanics.

Pneumatically driven left ventricular assist devices (LVADs) were acutely implanted between the left atria and the descending aortas of dogs, and were driven in five pumping modes: electrocardiogram synchronous modes with the duty factors of 1:1, 2:1, and 4:1, and asynchronous modes with the pulse rates of 60 and 80 beats/min (bpm). The ventricular diameter and myocardial segment length were measured by an ultrasonic displacement meter and implantable miniature sensors. Bulk mechanical work of the left ventricle and regional mechanical work of the myocardium were calculated from these dimensions and the left ventricular pressure. LVAD reduced the bulk mechanical work of the left ventricle by 30-50% and the regional work by 30-60%. The mean aortic pressure and the total flow (= aortic flow + pump bypass flow) were highest in the 1:1 synchronous pumping mode, which indicates that this mode is most effective to maintain the systemic circulation and coronary blood flow. Asynchronous pumping and synchronous pumping with 2:1 duty factor were most useful to reduce the mechanical work of the left ventricle.

Animals↗
PubMed1988

Saccadic eye movements evoked by microstimulation of the fastigial nucleus of macaque monkeys.

1. Systematic exploration throughout the deep cerebellar nuclei and white matter disclosed that the region from which saccadic eye movements (saccades) were evoked with weak currents (less than 10 microA) was confined to the fastigial nucleus and the adjacent white matter. 2. When an electrode for stimulation was advanced in the cerebellum, saccades were evoked in the direction of the stimulated side (ipsilateral saccades) as it entered the low-threshold region. In some tracks, particularly when the electrode was advanced in the medial portion of the fastigial nucleus, the direction of the evoked saccades changed from the ipsilateral to the contralateral. 3. The mappings with microstimulation disclosed that the ipsilateral saccades were elicited from a relatively wide region that included almost the full extent of the fastigial nucleus. The low-threshold region continued in the white matter caudally into vermal lobule VII and rostrally into the dorsal aspect of the brachium conjunctivum. On the other hand, the contralateral saccades were evoked from a relatively circumscribed region in the ventromedial portion of the fastigial nucleus. 4. The reversal in the direction of the horizontal component occurred always in a narrow zone in the core of the fastigial nucleus. The caudal part of this zone coincided with an ellipsoidal region where anterogradely labeled axons of the Purkinje cells terminated when HRP was injected into vermal lobule VII. 5. When bicuculline (0.2-1 microgram) was injected in the ellipsoidal region, the ipsilateral saccades evoked from the dorsocaudal aspect of the region were suppressed for several hours. On the other hand, the contralateral saccades evoked from the ventromedial portion of the fastigial nucleus were either unchanged or enhanced. 6. Because the ipsilateral saccades were suppressed by bicuculline, they were most probably evoked by stimulation of the presynaptic component of gamma-amino-butyric acid-(GABA) mediated synapses, namely the axons of Purkinje cells. 7. Because stimulation of the presynaptic component of the inhibitory synapses evoked ipsilateral saccades, activation of the postsynaptic component would evoke contralateral saccades. In fact, the distribution of the fastigial sites yielding contralateral saccades coincided with the course of axons of fastigial neurons arising in the ellipsoidal region. It is most likely, therefore, that the contralateral saccades were evoked by stimulation of fastigial neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗