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Biomedical subjects

N Yamazaki

Publications and source records attributed to N Yamazaki.

At least 271 records · Page 15Linked to original sources
PubMed1983

Production, purification, and properties of a bacteriocin from Staphylococcus aureus isolated from saliva.

Staphylococci from samples of human saliva were isolated on staphylococcal-selective agar plates. These strains were tested for the inhibition of the growth of Staphylococcus aureus FDA209P. The frequency of inhibitory strains among all of the staphylococcal isolates was 5.2%. Strain IYS2, which formed the biggest inhibitory zone against the growth of the indicator strain, was used as the producer of bacteriocin. IYS2 was identified to be S. aureus, based on its biological properties. The bacteriocin was purified by sequential procedures, including ammonium sulfate precipitation, fractionation with ethanol, ion-exchange chromatography, and gel filtration. Its molecular weight was determined to be 5,000. The isoelectric point was 10.0. In amino acid composition, lysine, histidine, aspartic acid, valine, and phenylalanine were predominant. The bacteriocin was heat stable but inactivated by proteases or peptidase. The bacteriocin had a bactericidal effect on susceptible cells. An analysis of the inhibitory spectrum among typical oral indigenous bacteria showed that Streptococcus salivarius, Propionibacterium acnes, Corynebacterium parvulum, and Actinomyces israelii were susceptible to the bacteriocin. Streptococcus mutans, Streptococcus sanguis, Streptococcus mitis, Actinomyces viscosus, Actinomyces naeslundii, Fusobacterium nucleatum, Bacterionema matruchotii, and Bacteroides melaninogenicus were resistant. The majority of S. aureus tested were susceptible, and all Staphylococcus epidermidis strains tested were resistant.

Amino Acids↗
PubMed1983

Ring chromosome 10 and its clinical features.

A 2-year-old boy with mental and growth retardation is presented; he has a 46,XY,r(10)(p15q26) chromosome complement. Five previously reported cases of ring chromosome 10 were reviewed and compared with the present case in an attempt to delineate a clinical syndrome. Since the first description, identified by Giemsa banding by Lansky et al, four other r(10) patients have been described. Their common features were mental and growth retardation, low birth weight, microcephaly, stubby nose, hypertelorism, strabismus, wide set nipples, single transverse palmar creases, undescended testes, and hypoplastic scrotum. In some of the cases congenital heart disease was present.

Child, Preschool↗
PubMed1983

Plasma norepinephrine concentration and plasma dopamine-beta-hydroxylase activity in patients with congestive heart failure.

The relationship between plasma norepinephrine (NE), epinephrine (E) and dopamine-beta-hydroxylase activity (DBH) was studied in 90 cardiac patients (New York Heart Association [NYHA] classes I-IV), 85 healthy control subjects and 18 competitive skiers. The cardiac patients in NYHA classes III and IV had significantly higher NE (p less than 0.001) and lower DBH (p less than 0.001) levels than the controls, whereas the skiers had significantly lower NE (p less than 0.001) and higher DBH (p less than 0.05) levels than the controls. Seven cardiac patients in whom successful cardiac surgery was performed had decreased NE (p less than 0.001) and increased DBH (p less than 0.02), as well as significantly improved NYHA cardiac status (p less than 0.001). These findings demonstrate an inverse relationship between NE and DBH in a population of athletes, normal subjects and cardiac patients; the same inverse relationship holds for these patients when sequential studies are done after a change in cardiac status.

Adolescent↗
PubMed1983

Effects of L-carnitine on ventricular arrhythmias after coronary reperfusion.

Effects of L-carnitine on ventricular arrhythmias and myocardial metabolism in a reperfused ischemic myocardium were studied in 35 anesthetized mongrel dogs. The left anterior descending coronary artery was ligated for 40 min and then reperfused for 15 min. L-carnitine (100 mg/kg) was administered intravenously 5 min before the coronary ligation and infused continuously at a rate of 20 mg/kg/min from 5 min before the reperfusion to the end of the experiment. Electrocardiograms were recorded continuously throughout the experiment. Transmural myocardial samples were obtained from both the ischemic and the nonischemic areas after 15 min of reperfusion and used for the determination of ATP, free carnitine, long chain acyl carnitine and long chain acyl CoA. L-carnitine significantly reduced the incidence rate of ventricular fibrillation after reperfusion (from 29% in the controls to 5%, p less than 0.05). ATP in the ischemic myocardium in the L-carnitine group was significantly higher than that in the control group (p less than 0.05). Free carnitine in the control group significantly decreased in the ischemic area as compared with the nonischemic area (p less than 0.01). In L-carnitine group, on the other hand, no difference was observed between them. Long chain acyl CoA in the control group significantly increased in the ischemic area as compared with the non-ischemic area (p less than 0.01). In L-carnitine group, on the other hand, no difference was observed between them. Thus, the accumulation of long chain acyl CoA in the ischemic myocardium was reduced by the L-carnitine treatment. These data suggest that L-carnitine has protective effects on ventricular arrhythmias and on metabolic changes after coronary artery reperfusion following coronary artery occlusion.

Animals↗
PubMed1983

Wolff-Parkinson-White syndrome with gradual transition from type A to type B.

This report documents a case which showed type A, type B and intermediate patterns of pre-excitation on different days. A vagotonic maneuver and digitalis induced a type A pattern, while exercise, atropine and isoproterenol caused a type B pattern of activity. A gradual transition from type A to B was demonstrated with vectorcardiograms. Despite the variations in the QRS morphology, the direction of the initial vector was not altered and was directed straight anteriorly. In this case, an accessory pathway may be located in the posterior paraseptal region or the lateral free wall of the left ventricle, and a variable size of pre-excited area may have caused type A and type B patterns of pre-excitation.

Delta Rhythm↗
PubMed1983

[Case of simultaneous multiple primary lung cancer].

The incidence of multiple primary bronchogenic carcinomas has increased in Japan as the incidence of bronchogenic malignancy has increased. The patient was a 71-year-old man with simultaneous multiple bronchogenic carcinomas. He had large cell carcinoma in the left upper lobe and adenocarcinoma in the left lower lobe. We reviewed 66 reported Japanese cases with multiple lung cancers with special reference to sex distribution, age, simultaneous or metachronous, location, histological types, treatment and prognosis.

Adenocarcinoma↗
PubMed1983

[Interaction with cholinergic drugs in reversal of cycloheximide-induced amnesia by thyrotropin-releasing hormone and its analog DN-1417 in mice].

The reversal effect of drugs on experimental amnesia was studied using one-trial passive avoidance task in mice. Cycloheximide (120 mg/kg) given sc 30 min before the acquisition of avoidance response caused amnesia by showing short latency to enter from the safety compartment into the shocked compartment in the retention test conducted 24 hours later. In these cycloheximide-treated animals, physostigmine (0.1 mg/kg), thyrotropin-releasing hormone (TRH: 10-20 mg/kg) and DN-1417 (5-20 mg/kg) given sc 15-60 min before the retention test markedly prolonged response latency, indicating reversal of amnesia. The effects of all these drugs were almost completely antagonized by anticholinergic drug, scopolamine (0.4-10 mg/kg). Although physostigmine when administered in conjunction with TRH potentiated the reversal effect, there was no potentiation with DN-1417. Since these drugs did not affect test performance in the cycloheximide-treated mice which had experienced no foot-shock, it is unlikely that the amnesia-reversing effect of the drugs was a result of non-specific suppression on motor activity. These results suggest that cholinergic activation reverses cycloheximide-induced amnesia, and TRH and DN-1417, while they showed a difference in the action of potentiation with physostigmine, may also activate a retrieval process of memory by mediation of cholinergic mechanism.

Amnesia↗
PubMed1983

[Effects of propranolol and atenolol on the rat kidney].

The present experiments were designed to study the renal effects of propranolol and atenolol in rats. Wistar rats were anesthetized with urethane and continuously hydrated with saline solution. In one group of the rats, the drugs were injected into the jugular vein. In the other group of the rats, the drugs were injected into the abdominal aorta through a canula which was inserted from the left carotid artery into the aorta up to the middle between forking points of left and right renal arteries. Intravenous infusion of propranolol and atenolol increased urine volume (UV), urinary sodium excretion, urinary potassium excretion and urinary chloride excretion. Propranolol and atenolol, which were intraaortally injected, produced an increase in UV and sodium concentration in the urine, inducing a more marked increase in total sodium amount excreted from both kidneys by propranolol than by atenolol. However, the natriuretic response was far more marked in the left kidney than in the right kidney in the case of atenolol administration as compared to that in the case of propranolol. It was speculated, therefore, that the natriuresis induced by these drugs was the first pass effect on the rat kidneys. It was also noted that the first pass effect of atenolol on kidneys was more marked than that of propranolol.

Animals↗
PubMed1982

Effects of L-carnitine on arrhythmias during hemodialysis.

The therapeutic effect of L-carnitine on arrhythmias during hemodialysis was evaluated in 17 patients with chronic renal disease undergoing intermittent hemodialysis. In 11 of 17 patients (65%), ventricular or supraventricular premature beats appeared at 20 to 30 min after the start of hemodialysis and continued throughout the dialysis. Plasma carnitine was at a lower level in the predialysis period (24.8 +/- 7.9 n mole/ml) as compared with the normal human levels (46.1 +/- 8.6 n mole/ml), and decreased markedly by the end of dialysis (8.2 +/- 5.9 n mole/ml). Plasma free fatty acids rapidly increased immediately after the start of dialysis, reached the maximum levels after 20 min (from 0.23 +/- 0.09 to 1.31 +/- 0.64 mEq/L) and maintained higher levels even at the end of dialysis (0.76 +/- 0.29 mEq/L). Administration of L-carnitine (2 Gm orally), 2 hours before the start of dialysis maintained plasma carnitine within normal levels throughout the dialysis and suppressed the increase in plasma free fatty acids. Both the incidence and the severity of premature beats during hemodialysis were significantly reduced by oral administration of L-carnitine (2 Gm daily) for 4 to 8 weeks. These results suggest that L-carnitine is useful for the treatment of hemodialysis arrhythmias, presumably by restoring impaired oxidation of free fatty acids.

Adult↗
PubMed1982

Effects of L-carnitine on action potential or canine papillary muscle impaired by long chain acyl carnitine.

It has been reported that long chain acyl carnitine accumulates in ischemic myocardium, and L-carnitine prevents ventricular arrhythmias as well as the accumulation of long chain acyl carnitine in ischemic and free fatty acid supplemented hearts. The purpose of this study was to observe the electrophysiological effects of long chain acyl carnitine, and to evaluate the protective effect of L-carnitine on the transmembrane action potential impaired by long chain acyl carnitine. Using standard microelectrode techniques, transmembrane action potentials were recorded from isolated canine papillary muscle. Palmitoyl carnitine (0.3 mM and 0.6 mM) decreased the resting membrane potential, action potential amplitude and maximum upstroke velocity of phase 0, and shortened action potential duration and effective refractory period in a concentration-dependent manner. Application of L-carnitine (25 mM) prevented the effect of palmitoyl carnitine (0.3 mM) on the transmembrane action potential. These results suggest that long chain acyl carnitine plays an important role in arrhythmogenesis, and that the effect is prevented by L-carnitine.

Action Potentials↗
PubMed1982

Enhanced protein synthesis of heart in adrenal-regeneration hypertension and its reduction following antihypertensive treatment.

After unilateral nephrectomy and bilateral adrenal enucleation at 5 weeks of age, salt-loaded rats developed hypertension (ARH) at 6 weeks. Fibrous vascular protein and in vivo incorporation of 3H-lysine into this protein fraction were measured at 15 weeks of age in these animals. This study demonstrates: (1) that incorporation rates of 3H-lysine into cardiac collagen and elastin in ARH rats were greater than in control rats (p less than 0.001, respectively), and (2) that administration of phenoxy-benzamine hydrochloride decreased the incorporation of tritiated lysine into cardiac collagen in ARH rats, concomitant with a reduction in blood pressure. Based on these findings, increased synthesis of cardiac collagen and elastin appears to play an important role in the development of hypertension in ARH.

Adrenal Glands↗