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Biomedical subjects

N Hata

Publications and source records attributed to N Hata.

At least 73 records · Page 4Linked to original sources
PubMed1994

An image-guided stereotactic system for neurosurgical operations.

A new simulation system utilizing digital images (CT/MRI/SPECT) and an ultrasound/laser navigation system has been developed for image-guided surgery. Preoperative CT/MRI imaging does not always indicate the actual location of the lesion during intracranial operation, because the lesion may be displaced or distorted by operative procedures or CSF flowout. The authors developed an image integration system including an intraoperative ultrasonogram, which provides accurate information not only on the location of the deep-seated lesions but also surrounding anatomical structures during operation. The rationale of the system is to coordinate the three-dimensional axes of each image with the aid of a stereotactic subframe. Our simulation system has two ways. One simulation system works on a SUN workstation. At the preoperative simulation study: the entry point on the brain surface and the access route to the lesion are decided on from the three-dimensional CT/MRI images on the computer display. Then the configuration of the lesion from the operative view is displayed as an expected ultrasound image by reconstructing the CT and/or SPECT image. Another simulation system (HyperCAS) works on the HyperCard of a MacIntosh. The target point, the entry point and the trajectory are decided on and the three-dimensional location of these points is measured from serial CT images on the LCD display. At the time of operation, stereotactic craniotomy is performed using the laser navigator. The extent of the lesion at every depth in the surgical process is predicted from these images, and the access route to the lesion is easily corrected with the intraoperative ultrasound navigator.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Simulation↗
PubMed1994

Clinical significance of coronary artery calcification.

Coronary artery calcification (CAC) was easily demonstrated by plain CT-scan. The aim of this study was to clarify the clinical significance of CAC in cardiovascular diseases. The subjects were 90 patients with ischemic heart disease (30 myocardial infarction, 50 exertional angina pectoris and 10 variant form of angina pectoris; 46 males and 44 females, 68 +/- 10 y/o) and 50 patients without ischemic heart diseases (30 hypertension, 10 arrhythmia, 3 valvular disease, 2 cardiomyopathy, 2 congenital heart disease and 3 others; 25 males and 25 females 65 +/- 9 y/o). CAC and calcification of thoracic aorta were evaluated by plain CT-scan (1 second scan time and 5 mm slice). The relationship between CAC and other clinical features (age, sex, hypertension, diabetes mellitus, hyperlipidemia, smoking, resting ECG, exercise stress ECG, aortic calcification and optic fundi) were studied. CAC were seen more frequently in patients with ischemic heart disease (63%), old age (67%), aortic calcification (70%) and positive exercise testing (64%). On the other hand, CAC were rare in variant angina (30%). In younger patients (under 70 y/o), CAC were seen more frequently in diabetic patients. But, in older patients, CAC were frequently in those with hyperlipidemia. These results suggested that CAC was associated with not only systemic arteriosclerosis, but also ischemic heart disease, except vasospastic angina. The prognostic value of CAC would be studied later.

Age Factors↗
PubMed1993

Neuroendocrine and neurochemical responses to novelty stress in young and old male F344 rats: effects of d-fenfluramine treatment.

To understand some of the mechanisms underlying the neuroendocrine and neurochemical changes associated with aging, we administered the serotonin [5-hydroxytryptamine (5-HT)] releaser and reuptake inhibitor d-fenfluramine (d-FEN; 0.0, 0.2, or 0.6 mg/kg/day, p.o) for 30-38 days to young (4 months) and old (22 months) F344 male rats. Rats were stressed by placement into a novel open field (OF) for 20 min before sacrifice. Control animals were sacrificed immediately upon removal from their home cage (HC). Old rats exhibited less (p < 0.05) exploratory behavior than young rats, which was not altered by treatment with d-FEN. Old HC rats also had higher (p < 0.05) basal plasma levels of adrenocorticotropic hormone (ACTH) and prolactin (PRL) than young HC rats. Old OF rats showed higher (p < 0.05) levels of ACTH and corticosterone (CORT) than young OF animals. A stress-induced increase in PRL secretion was not observed in old rats. Subchronic low-dose d-FEN normalized the enhanced ACTH and CORT responses of old animals to novelty. In addition to these endocrine changes, stress-induced increases in medial frontal cortex (MFC) dopamine (DA) and norepinephrine (NE) turnover also were observed. The increase in NE turnover was greater (p < 0.01) in old than in young rats. d-FEN treatment blocked the stress-induced increase in MFC NE but not MFC DA turnover in both young and old rats. These data support a role for 5-HT and/or NE in some age-related neuroendocrine perturbations and suggest that increased 5-HT neurotransmission can normalize the hyperactivation of the hypothalamo-pituitary-adrenal axis of old male rats.

Adrenocorticotropic Hormone↗
PubMed1993

Therapeutic effect of granulocyte colony-stimulating factor and cephem antibiotics against experimental infections in neutropenic mice induced by cyclophosphamide.

Effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) against severe infections in cyclophosphamide (CY)-induced neutropenic mice were investigated by its single use or by its combination with cephem antibiotics. Treatment with rhG-CSF increased the number of peripheral blood leucocytes and strikingly shortened the duration of the neutropenic state. Most of the regained population in the peripheral blood leucocytes were neutrophils. Functions of neutrophils, such as phagocytic activity, superoxide release, and expression of Mac-1 molecules, were remarkably enhanced by administration of rhG-CSF. When rhG-CSF was administered to CY-induced neutropenic mice before infection, protective effects against various kinds of bacteria were remarkable. On the other hand, such remarkable effects were not observed when rhG-CSF was administered after infections. However, even in the case of post-infectious treatment, a combination therapy of rhG-CSF with cephem antibiotics, particularly with Cefodizime (CDZM), showed a significant improvement in the survival rate and a decrease in the number of viable bacteria in the liver. These results suggest that a combination therapy of rhG-CSF with cephem antibiotics, especially with CDZM, is an efficient regime against severe infections in patients with neutropenia induced by a heavy anti-tumour chemotherapy.

Animals↗
PubMed1993

Therapeutic effect of granulocyte colony-stimulating factor (G-CSF) on the protection against Listeria infection in SCID mice.

Anti-listerial activity in SCID mice as well as in control C.B-17 mice was augmented by granulocyte colony-stimulating factor (G-CSF). After 1 x 10(3) colony-forming units of Listeria monocytogenes (strain EGD) were intravenously inoculated, mice were intraperitoneally injected with G-CSF at a daily dose of 500 micrograms/kg for 5 days. The numbers of viable bacteria in the liver were significantly lower in G-CSF-treated SCID and C.B-17 mice than in non-treated mice. The surface marker analyses on gamma delta T-cell receptor (TcR), Mac-1 and F4/80, and dichlorofluorescein oxidative activity, showed a possible contribution of activated neutrophils, but not gamma/delta T cells nor activated macrophages, to the augmentation of anti-listerial activity in SCID mice. This study is one of the first reports on the anti-microbial effect of G-CSF in therapeutic use.

Animals↗
PubMed1992

Antianginal effects of amlodipine at a single dose on exertional angina patients using treadmill exercise testing--a randomized crossover study in comparison with placebo.

With eight cases of stable exertional angina as subjects, the antianginal action and sustained effects of single 10 mg oral doses of new calcium antagonists amlodipine were assessed by treadmill exercise tests in randomized crossover trials with respect to a placebo. Exercise tests were conducted before as well as 4, 8, and 24 hours after administration, and plasma amlodipine concentration was investigated at the same times. The maximal exercise time was 299 +/- 43 seconds before as compared with 346 +/- 49 seconds 4 hours after administration and 368 +/- 50 seconds 8 hours after administration, a significant prolongation in each case (p < 0.01). Moreover, the exercise time elapsed until 1 mm of ST-segment depression, as well as the ST-segment depression measured at the same time, were both significantly improved as compared with the placebo results. The plasma amlodipine concentration reached a peak 8 hours after administration and displayed an effective level even 24 hours after administration. The value of delta PRP measured at the same time during the exercise test was also significantly reduced as compared with the placebo results, even 24 hours after administration of amlodipine. These findings supported the conclusion that single 10-mg doses of amlodipine provide stable antianginal action over a 24-hour period.

Administration, Oral↗
PubMed1992

[Silent myocardial ischemia in myocardial infarction patients: its prognostic significance].

To evaluate the prognostic and clinical significance of silent myocardial ischemia (SMI), we examined cardiac events in 160 patients with old myocardial infarction who underwent ambulatory Holter monitoring, treadmill exercise testing and coronary angiography. Using the Cox's proportional hazard regression model and the survival curves with the Kaplan-Meier method, we identified the predictors of cardiac events. The incidence of cardiac events for all the patients during the 44-month follow-up period was 18%. The significant predictors of unfavorable outcomes were severe coronary lesions and SMI. The incidence of SMI was 38%. The cardiac event rate in patients with SMI was higher than in those without SMI (32 vs 9%, p < 0.05). The most frequent cardiac event in patients with SMI was reinfarction, and the significant predictors of cardiac events for these SMI patients were lower ejection fraction and maximum ST depression on Holter monitoring. In conclusion, SMI proved to be a significant predictor of unfavorable outcome in patients with old myocardial infarction. It was, therefore, suggested that revascularization (PTCA/CABG) should be used as early as possible in patients with SMI whether anginal symptoms are present or not.

Aged↗
PubMed1991

A new strategy for the reduction of acute myocardial infarction in variant angina.

To study the effects of stepwise early treatment in variant angina pectoris, frequencies of cardiac events and complications were examined after three different types of treatment. The subjects of the study consisted of 159 consecutive patients with variant angina pectoris, who were in need of hospitalization. The three treatment modalities were the introduction of calcium antagonists, nicorandil and nitroglycerin infusion, and percutaneous transluminal coronary angioplasty (PTCA), respectively. The cardiac event rate for this series of patients was 16% (25 of 159). The cumulative cardiac event rate was 22% at 1 year and 23% at 3 years in the first treatment period; 11% at the same intervals in the second treatment period; and 6% at the same intervals in the third treatment period. Our results suggest that it is important in the treatment of variant angina pectoris not only to prevent anginal attacks by the use of fast-acting coronary vasodilators, but also to initiate early revascularization.

Adult↗
PubMed1991

Possible involvement of lignin structure in anti-influenza virus activity.

Commercial lignins suppressed the growth of influenza A virus infecting MDCK cells, and the RNA-dependent RNA synthesis, as efficiently as the high-molecular weight fractions extracted from pine cone of Pinus parviflora Sieb. et Zucc. The anti-influenza A virus activity of both pine cone extract and commercial alkali-lignin was considerably reduced by treatment with sodium chlorite, but was not affected by sulfuric acid or trifluoroacetic acid. The degraded components of lignin, various synthesized polyphenols unrelated to lignin, and natural and chemically modified glucans, were not appreciably inhibitory. The data suggest that the polymerized phenolic structure of lignified materials is responsible for the anti-influenza A virus activity.

Animals↗
PubMed1991

Behavioral, endocrine, and neurochemical effects of sulfomucopolysaccharide treatment in the aged Fischer 344 male rat.

1. Daily treatment of male 19- to 22-month-old Fischer 344 male rats with Ateroid (20 mg/kg/day, p.o.), beginning one month before and continuing throughout testing, resulted in a significant partial reversal of age-related deficits in: a) Conditioned one-way (spatial, unsignaled) avoidance acquisition and retention b) Conditioned two-way (nonspatial, signaled) avoidance acquisition. 2. Ateroid reversed the age-related reductions in nucleus accumbens DOPAC and HVA levels, but not the age-related decrease in neostriatal HVA content or concomitant increase in 5-HIAA levels. Reduced dopamine turnover in the nucleus accumbens may underlie, at least in part, age-related deficits in conditioned avoidance learning and retention. Thus, the behavioral effects of Ateroid observed in the present study may be due to its normalizing influence on dopamine neurotransmission in the nucleus accumbens. 3. Stress-induced corticosterone secretion was greater in the old than in the young vehicle-treated rats. Ateroid treatment normalized this exacerbated corticosterone response to stress. 4. Daily Ateroid treatment did not affect any of the parameters measured in the young (5-8 months) F344 male rats. 5. Ateroid treatment did not affect the age-related reductions in exploratory behavior. The aged and young animals did not differ in their swimming ability. Thus, the effect of Ateroid on learning and memory processes does not appear to be due to an effect on locomotor or performance skills. 6. The age-related deficits in conditioned avoidance learning were not associated with abnormal basal (morning trough) plasma corticosterone levels, and Ateroid did not affect basal plasma corticosterone concentrations.

Aging↗
PubMed1991

[Stress myocardial scintigraphy in coronary artery disease: its clinical significance].

To evaluate the clinical significance of asymptomatic ischemic heart disease, exercise electrocardiography and stress myocardial scintigraphy were performed. These were correlated with symptoms during exercise tests and histories of myocardial infarction (MI). The study subjects consisted of 70 patients with coronary artery disease, including 34 with MI, and 36 without MI but with angina pectoris. Stress tests were performed using bicycle ergometer under electrocardiographic monitoring throughout the test. Transient myocardial ischemia was confirmed by perfusion defects on thallium myocardial imaging demonstrated immediately after exercise, but not 3 hours after the stress test. Asymptomatic ST depression was observed in 18 of 34 patients with MI (53%) and in 21 of the 36 patients with angina (58%); however, transient myocardial perfusion defects were confirmed in 61% of the patients with MI (11 of 18 patients), but in only 33% of those with angina (7 of 21 patients). The difference was statistically significant (p less than 0.05). It was suggested that there are some differences in the clinical significance of asymptomatic ST depression between the patients with MI and those without MI but with angina pectoris.

Aged↗
PubMed1990

Evidence for involvement of N-methyl-D-aspartate receptor in tonic inhibitory control of dopaminergic transmission in rat medial frontal cortex.

Bilateral infusion of DL-2-amino-5-phosphonovalerate (DL-APV) (which is a competitive antagonist for N-methyl-D-aspartate (NMDA) receptor) into the medial frontal cortex of conscious rats increased the amount of 3,4-dihydroxyphenylacetic acid (DOPAC) and the DOPAC/dopamine (DA) ratio in the cortical area. Moreover, intra-prefrontal injection of DL-APV, D-APV, DL-2-amino-7-phosphonoheptanoate and 3-[(+/-])-2-carboxypiperazin-4-yl]-propyl-1-phosphonate (which are selective NMDA receptor antagonists), but not the L-isomer of APV and gamma-glutamyl-aminomethyl sulphonate (a relative antagonist for non-NMDA receptors), facilitated prefrontal DA utilization in a NMDA-reversible manner. These findings suggest that NMDA-type excitatory amino acid receptors may be involved in a tonic inhibitory regulation of dopaminergic transmission in the medial frontal cortex in vivo.

2-Amino-5-phosphonovalerate↗
PubMed1990

Forensic application of angiography on injured brain.

Craniocerebral angiography, injecting radiopaque contrast medium through the common carotid arteries under the normal blood pressure, was a very useful way to search the cerebral injuries, especially the location of arterial rupture. We think our post-mortem examination using angiography will open up a new way to investigate cerebral injuries.

Adolescent↗