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Biomedical subjects

N Yamada

Publications and source records attributed to N Yamada.

At least 721 records · Page 40Linked to original sources
PubMed1989

[Cine MR imaging in valvular heart disease].

Cine MR Imaging was carried out using FLASH (fast low angle shot) which employees TE of 16 msec and TR of 30-40 msec. Regurgitant jet was visible as discrete area of low signal intensity extending from the incompetent valve into the respective cardiac chamber. In 20 patients with mitral regurgitation, the correlation of the length and area of mitral jet by cine MR and color doppler mapping was 0.74 and 0.71, respectively. Cine MR imaging is a promising modality for detection and quantification of valvular heart disease.

Aged↗
PubMed1989

[The effects of hyperthermia on cerebral blood flow, metabolism and electroencephalogram].

In practice of systemic or local hyperthermia, it becomes very important to determine the tolerance of the brain to heat, along with the evaluation of the influence of heat on brain function. In this little known area, the study was made by examining the changes of blood pressure, cerebral blood flow (CBF), partial pressure of oxygen and pH in the cerebral cortex, electroencephalogram (EEG) and somatosensory evoked potential (SEP), under hyperthermia by experiment. Unanesthetized and immobilized adult rabbits were used in the experiments under controlled respiration. The head alone or the whole body was heated by bathing in hot air. In the head heating, the brain temperature could be heated up to 45 degrees C without extreme fall of the blood pressure, and meantime the aortic blood maintained under 43.5 degrees C at that condition. In the head heating case, the CBF increased to two times at 43 degrees C, two and a half times at 44 degrees C, three and a half times at 45 degrees C of the cortical temperature. As the cortical temperature raised up, the partial pressure of oxygen and pH of the cerebral cortex increased. The peak frequency of power spectrum of EEG increased as the temperature was raised. High amplitude rhythmic slow wave burst appeared at over 44 degrees C for 30 minutes, which soon changed to a flat pattern. In the whole body bathing, on the contrary, the animals died of abrupt fall of the arterial blood pressure when the temperature of the aortic blood was raised over 43.5 degrees C, and it was impossible to get the brain heated over 43 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Biliary excretion and clinical efficacy of T-3262 (tosufloxacin tosilate) administered in the treatment of cholecystitis].

T-3262 (tosufloxacin tosilate), a new oral pyridone carboxylic acid agent, was investigated for its biliary excretion and clinical efficacy and safety to evaluate its usefulness in the treatment of cholecystitis. T-3262 was administered to a total of 4 healthy volunteers for 2 days at a dose of 150 mg every 8 hours, and A-, B- or C-bile were collected using the MELTZER-LYON method at 10-11 hours after the final administration. Bile concentrations of T-3262 in 3 cases were 0.33-2.05 micrograms/ml (A-bile), 6.13-9.50 micrograms/ml (B-bile) and 1.11-2.70 micrograms/ml (C-bile). Thus, T-3262 levels in B-bile were 15-34 times higher than serum levels (0.28-0.41 micrograms/ml). Only a trace of serum concentration of T-3262 was detected in another case with the concentration in B-bile was 0.132 micrograms/ml. A total of 10 patients with cholecystitis were treated with T-3262 at a dose level of 150 mg per dose 3 times daily for 1 to 20 days. The clinical efficacy was excellent in 1 case, good in 5 cases and fair in 2 cases and unevaluable in 2 cases, thus the clinical efficacy rate was 75%. Bacteriologically, Klebsiella pneumoniae, Enterococcus faecalis and Haemophilus parahaemolyticus were isolated from biles of 3 patients before treatment. Upon the treatment, E. faecalis was eradicated and K. pneumoniae was unchanged. The fate of H. parahaemolyticus was not known because of examination was not done after treatment. Side effects were observed in 2 cases with diarrhea in 1 case and epigastric pain in another case. But those symptoms disappeared after cessation of administration of T-3262. Abnormal laboratory test values were not observed.

4-Quinolones↗
PubMed1988

Enhanced synthesis and secretion of apolipoprotein E from sciatic nerves of streptozotocin-induced diabetic rats after injury.

To elucidate the pathogenesis of diabetic neuropathy, synthesis and secretion of apolipoprotein E (apo E) from sciatic nerves after injury was studied in normal and streptozotocin-induced diabetic rats. Seven, 14, 28, 45 and 59 days after making crush injury on sciatic nerves with concomitant administration of streptozotocin (50 mg/kg body weight), the nerves were taken out and incubated with [35S]methionine. The [35S]labeled apo E was precipitated with specific antiserum. The amounts of apo E secreted into medium by nerves of diabetic rats were 7 times greater than those of non-diabetic rats 7 days after injury. This enhanced secretion of apo E was relatively selective for this protein, since the ratio of the immunoprecipitable apo E to the TCA preciptitable protein in the medium increased in diabetic rats. Intriguing possibility deduced from these results is that the secretion of apo E is involved in the development of diabetic neuropathy.

Animals↗
PubMed1988

Femtosecond charge separation in organized assemblies: free-radical reactions with pyridine nucleotides in micelles.

Femtosecond laser UV pulse-induced charge separation and electron transfer across a polar interface have been investigated in anionic aqueous micells (sodium lauryl sulfate) containing an aromatic hydrocarbon (phenothiazine). The early events of the photoejection of the electron from the micellized chromophore and subsequent reaction of electron with the aqueous perimicellar phase have been studied by ultrafast infrared and visible absorption spectroscopy. The charge separation (chromophore +...e-) inside the micelle occurs in less than 10(-13) s (100 fs). The subsequent thermalization and localization of the photoelectron in the aqueous phase are reached in 250 fs. This results in the appearance of an infrared band assigned to a nonrelaxed solvated electron (presolvated state). This transient species relaxes toward the fully solvated state of the electron in 270 fs. In anionic aqueous micelles containing pyridine dinucleotides at high concentration (0.025-0.103 M), a single electron transfer can be initiated by femtosecond photoionization of phenothiazine. The one-electron reduction of the oxidized pyridine dinucleotide leads to the formation of a free pyridinyl radical. The bimolecular rate constant of this electron transfer depends on both the pH of the micellar system and the concentration of oxidized acceptor. The free-radical reaction is analyzed in terms of the time dependence of a diffusion-controlled process. In the first 2 ps following the femtosecond photoionization of PTH inside the micelle, an early formation of a free pyridinyl radical is observed. This suggests that an ultrafast free-radical reaction with an oxidized form of pyridine nucleotide can be triggered by a single electron transfer in less than 5 X 10(11) s-1.

Adenosine Monophosphate↗
PubMed1988

Magnetic resonance imaging of cerebral infarction: time course of Gd-DTPA enhancement and CT comparison.

Thirty-five patients (7 females and 28 males) with cerebral infarction and suspicion of cerebral infarction of 4 h to 27 months duration were studied 45 times with magnetic resonance (MR) imaging using Gd-DTPA. Spin echo (SE) images were obtained before and after the administration of Gd-DTPA (0.1 or 0.15 mmol/kg) and compared with the enhanced CT. MR imaging using Gd-DTPA was more sensitive than enhanced CT and very useful for detecting a new focus of cerebral infarction, especially in the cases with multiple infarcted areas and for showing the extent of cortical and subcortical infarction. In most cases the MR enhancement was obvious in the subacute stage, especially after cerebral embolism, and the signal intensity of the lesion tended to show a gradual increase. The diagnosis of embolism was accepted on the basis of acute onset without prior TIA, coupled with angiography showing the embolus itself and/or a capillary blush and a wide area of infarction.

Adult↗
PubMed1988

Computerized morphometry of liver cells in diffuse hepatic diseases.

Computerized morphometrical measurements were made of liver cells and their nuclei taken from livers of healthy persons and from patients with acute hepatitis (AH), chronic hepatitis (CH), and liver cirrhosis (LC). Liver biopsies were performed on 127 people (24 convalescing from acute hepatitis, 20 with chronic inactive hepatitis (CIH), 24 with chronic active hepatitis (CAH), 38 with liver cirrhosis (LC) and 21 who were healthy controls (HC]. The specimens were stained with hematoxylin-eosin, then light microscopic pictures were obtained. The original cells were magnified 1000 times. The sizes of the cells and of their nuclei were calculated using a computer. Correlative variation was noted in cell and nuclear sizes resulting in an consistently constant nucleus-cytoplasm ratio. Average sizes of both cells and nuclei were maximal in livers with LC, followed in decreasing order by those in livers with CAH, CIH, HC and convalescent AH. The smallest cells and nuclei were found in convalescent AH cases. It might be possible to some degree to obtain gross impressions of the histopathological type of the liver lesion by measuring the sizes of cells and nuclei of the liver.

Biopsy↗
PubMed1988

A study of DNA polymorphism in the apolipoprotein B gene in a Japanese population.

A Japanese group comprising 53 hyperlipidemic and 54 normolipidemic subjects was genotyped for DNA restriction fragment length polymorphisms (RFLPs) at the apo B gene locus. The polymorphisms with XbaI and PvuII were present at allelic frequencies of 0.04 (X1 allele) and 0.96 (X2 allele), 0.94 (P1 allele) and 0.06 (P2 allele), respectively. Unlike the previous reported association of the X1 allele with hypercholesterolemia found in Caucasians there was no difference in the frequency of the X1 allele between normolipidemic and hypercholesterolemic Japanese. Among the Japanese, two RFLPs appear to be in linkage equilibrium and can be used in conjunction as a haplotype. There is no strong population association in our patient group between any allele of the RFLPs studied and hyperlipidemia.

Adult↗
PubMed1988

Free-access to a running wheel shortens the period of free-running rhythm in blinded rats.

The period of free-running rhythm was measured with two different devices, Automex and running wheel, in blinded female rats. The period was significantly shorter when measured with a running wheel than with an Automex. After transfer between the two devices, all 13 rats examined showed the same direction of change in the free-running period and that transfer from the Automex to running wheel shortened the period, while transfer from the running wheel to Automex elongated it, with the exception of two rats who did not show any significant change in the period even when they were transferred twice. These results indicate that free access to a running wheel shortens the free-running period in female blinded rats.

Animals↗
PubMed1988

Chronic administration of tricyclic antidepressants suppresses hypothalamo-pituitary-adrenocortical activity in male rats.

The effect of chronic administration of the clinically effective antidepressants, imipramine, clomipramine and desipramine, on corticosterone (CS) release in male rats was investigated. Chronic administration of imipramine, clomipramine and desipramine at a dose of 20 mg/kg b.w./day, but not at a dose of 2 mg/kg b.w./day, suppressed blood CS concentration at 2000h and abolished its circadian rhythm. The normal circadian rhythm of CS release resumed seven days after the termination of imipramine injection. The acute administration of imipramine (20 mg/kg b.w./day) at 0800h but not at 2000h elevated CS concentrations. Chronic administration of imipramine (20 mg/kg b.w./day) tended to increase the inhibitory effect of dexamethasone on CS release. Adrenocortical sensitivity to exogenous adrenocorticotropic hormone tended to be decreased by chronic administration of imipramine (20 mg/kg b.w./day). These results indicate that antidepressants have effects on the hypothalamo-pituitary-adrenocortical axis which may confound psychoneuroendocrinological tests, such as the dexamethasone suppression test, for the diagnosis of affective disorders.

Adrenal Cortex↗
PubMed1988

Total parathyroidectomy with forearm autograft for secondary hyperparathyroidism in chronic renal failure.

One hundred twenty-eight patients with chronic renal failure and secondary hyperparathyroidism underwent total parathyroidectomy with forearm autograft. Postoperative clinical improvement was remarkable. In all cases, the grafted tissue functioned well, and reimplantation of the cryopreserved parathyroid tissues was unnecessary. Intact 1-84 parathyroid hormone was more sensitive than C-terminal parathyroid hormone in parathyroid hormone level (PTH) gradient assays of grafted and nongrafted forearm. The study of hypocalcemia was also helpful in obtaining more distinct PTH gradients. Five of 119 patients had supernumerary parathyroid glands (4.2%), which preoperative noninvasive image diagnosis of parathyroid glands was helpful in detecting.

Adult↗
PubMed1988

Metabolism of apolipoprotein B-100 in large very low density lipoproteins of blood plasma. Kinetic studies in normal and Watanabe heritable hyperlipidemic rabbits.

The metabolism of radioiodinated apo B-100 in large VLDL from normal and Watanabe heritable hyperlipidemic (WHHL) rabbits, with diameters exceeding 450 A, was studied in corresponding recipient rabbits. In both cases approximately 87% of the particles contained apolipoprotein (apo) E (B,E particles). In normal rabbits, apo B in these B,E particles was removed from blood plasma much more rapidly than apo B in B,E particles in smaller VLDL and few of the large B,E particles were converted to lipoproteins of higher density. In WHHL rabbits, approximately 60% of the apo B in B,E particles in large VLDL was removed at a comparably rapid rate, but an appreciable fraction of the remainder, which was removed slowly, was converted to particles of higher density, as are the B,E particles in smaller VLDL. From kinetic analysis of these and other data, an hypothesis was formulated from which it is estimated that apo B in large VLDL accounts for 18 and 41% of apo B transport in normal and WHHL rabbits, respectively, despite the fact that these lipoproteins contain less than 5% of the apo B in total VLDL. Failure to account for the contribution of large VLDL to VLDL turnover may lead to serious underestimation of total apo B transport in the blood.

Animals↗
PubMed1988

The QRS complex of the standard 12-lead electrocardiogram in septal myocardial infarction.

Interventricular septal involvement in myocardial infarction is suggested by the findings of a QS deflection in lead V1 and/or absence of the Q wave in leads I and V6, using the standard 12-lead electrocardiogram (ECG). However, these findings were not sufficiently established for the criteria of septal infarction, because several factors including anatomic position of the heart, changes of intraventricular conduction, and condition of the lung would affect the QRS complex in the leads. In this study, we analyzed the ECGs of anterior myocardial infarction with (group A) and without (group B) involvement of the first septal coronary artery. The R wave in V1 was absent in 64.7% of group A and 60.0% of group B. The Q wave was absent in 35.3% in lead I and 64.7% in lead V6 of group A, while in group B the Q wave in leads I and V6 were not observed in 60.0% and 40.0%, respectively. The prevalence rates of the R wave and the Q wave in these leads were not significantly different between the two groups. Left ventriculography revealed that the prevalence rate of the R wave in V1, and the Q wave in I and V6 was not significantly different, regardless of the presence or absence of impaired septal motion. Experimental study in anesthetized dogs confirmed the difficulty in clarifying acute septal ischemia by changes in the QRS complex. These results indicate that septal myocardial infarction is hardly detectable with changes in the QRS complex of the standard 12-lead electrocardiogram.

Coronary Vessels↗
PubMed1988

Effect of heart rate and myocardial contractile force on coronary resistance.

The effect of the heart rate and myocardial contractile force on the extravascular resistance to blood flow of the left anterior descending coronary artery (LAD) was evaluated in 15 mongrel dogs anesthetized with sodium pentobarbital. The LAD was maximally dilated by intracoronary infusion of adenosine, which precluded the influence of vasomotor tone. Increases in the heart rate and myocardial contractile force decreased coronary blood flow in the absence of a change in coronary perfusion pressure. The changes in mean coronary resistance showed a significant linear relationship to changes in developed tension. The changes in coronary resistance caused by varying the heart rate and contractile force were so small that a normal coronary vascular tree could easily compensate for the increase in resistance. However, it is supposed that with critical stenosis of the vascular tree even a small increase in resistance might cause deleterious effects on coronary blood flow.

Adenosine↗