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Biomedical subjects

K Nishimura

Publications and source records attributed to K Nishimura.

At least 163 records · Page 9Linked to original sources
PubMed1989

Neurofibromatosis types 1 and 2: cranial MR findings.

Neurofibromatosis 1 (NF-1) (von Rekhlinghausen disease) and neurofibromatosis 2 (NF-2) (bilateral acoustic neurofibromatosis) have been recently recognized to be distinct disorders through genetic linkages. The authors compared the cranial magnetic resonance (MR) images of 53 patients with NF-1 and 11 with NF-2. In the NF-1 group, MR imaging revealed 19 patients with optic gliomas and eight with parenchymal gliomas. In 32 patients, foci of prolonged T2, similar to those reported previously as hamartomas, were identified in the cerebellar peduncles, globus pallidus, midbrain, and other locations. The frequency of these foci was related to both age and the presence of optic gliomas. In the NF-2 group, MR imaging revealed eight patients with cranial nerve schwannomas and six with meningiomas (in addition to acoustic schwannomas in all 11). These findings demonstrate that NF-1 and NF-2 are different diseases requiring different imaging protocols. NF-1 seems to be associated with tumors of astrocytes and neurons and NF-2 with tumors of meninges and Schwann cells.

Adolescent↗
PubMed1989

Normal deposition of brain iron in childhood and adolescence: MR imaging at 1.5 T.

Magnetic resonance (MR) images of the brain in 285 patients between the ages of 2 and 25 years were retrospectively studied to determine the appearance of brain iron accumulation. The globus pallidus, red nucleus, substantia nigra, and dentate nucleus were evaluated with long TR/TE (repetition time/echo time) spin-echo sequences and staged. All four regions in most patients were initially hyperintense compared with white matter (stage I) before becoming isointense (stage II) and subsequently hypointense (stage III). The globus pallidus was the first to reach stage III, the red nucleus and substantia nigra were next, and the dentate nucleus was last. In general, decreased signal intensity (stage III) was not seen in these regions in patients less than 10 years old; in most patients it was seen by age 25 years. The dentate nucleus decreased in signal intensity more slowly and inconsistently; only one-third of patients had reached stage III by age 25 years. The temporal sequence of normal iron deposition as detected with MR imaging is helpful not only in the diagnosis of known iron-deposition diseases but also in the detection of iron-related pathologic changes.

Adolescent↗
PubMed1989

Gamna-Gandy bodies of the spleen: evaluation with MR imaging.

The authors retrospectively evaluated magnetic resonance (MR) images obtained in 64 patients with portal hypertension. Multiple low-intensity nodules were noted within the spleen in eight patients. In all eight cases, these nodules were most apparent on images obtained with the GRASS (gradient-recalled acquisition in the steady state) technique, which is known to be more sensitive to heterogeneity of the magnetic susceptibility, usually caused by hemosiderin deposition. In one of these cases, ultrasonography demonstrated diffuse hyperechoic spots that had been reported to represent Gamna-Gandy bodies of the spleen (ie, organized hemorrhage caused by portal hypertension). Although there was no pathologic proof in their series, the authors believe these low-intensity nodules seen on MR images may represent the hemosiderin deposits of Gamna-Gandy bodies.

Adult↗
PubMed1989

Augmented expression of atrial natriuretic polypeptide gene in ventricle of human failing heart.

To elucidate the expression of the atrial natriuretic polypeptide (ANP) gene in the ventricle of the human failing heart, we have measured ANP and ANP messenger RNA (ANPmRNA) levels in left ventricular aneurysm obtained at operation, biopsy specimens of left ventricles from dilated cardiomyopathy (DCM) and autopsy samples of old myocardial infarction (OMI) and DCM hearts, and compared the levels with those in the normal ventricle. The ANP level (mean +/- SE) was 17.5 +/- 6.9 ng/g in the normal ventricle, and increased to 660.3 +/- 122.2 ng/g in the left ventricular aneurysm tissues and to 3,138.6 +/- 1,642.1 ng/g in the biopsy specimens of the DCM ventricle. These levels were approximately 40 and 200 times higher than in the normal ventricle. The increase of ANP levels was observed in both infarcted and noninfarcted regions of the OMI heart, and in the entire ventricle of the DCM heart. A significant positive correlation was found between the ANP level in aneurysm tissues and pulmonary capillary wedge pressure (r = 0.85). The ANPmRNA level in the left ventricular aneurysm showed about a 10-fold increase compared with that in the normal heart and reached 23% of that in the atrium of the same heart. A similar increase in the ANPmRNA level was observed in the entire ventricle of DCM. These data clearly indicate that the expression of the ANP gene in the ventricle is augmented in the failing heart in accordance with the severity of heart failure. In the atrium of the failing heart, ANP and ANPmRNA levels were only two times higher than those in the normal atrium. Thus, the augmentation in the expression of the ANP gene was more prominent in the ventricle than in the atrium. Taking tissue weight into account, the total content of ANPmRNA in the ventricle of the failing heart is much the same as that in the normal atrium. The ratio of the ANP level to the ANPmRNA level in the ventricle is much smaller than that in the atrium. These results suggest more rapid secretion of ANP after synthesis in the ventricle. These findings demonstrate that the expression of the ANP gene is augmented in the human ventricle of the failing heart and suggest that the ventricle becomes a substantial source of circulating ANP in congestive heart failure.

Aged↗
PubMed1989

Angiotensin-converting enzyme inhibitors: synthesis and structure-activity relationships of potent N-benzyloxycarbonyl tripeptide inhibitors.

A new series of gamma-D-Glu-containing N-benzyloxycarbonyl (Z) tripeptide inhibitors of angiotensin-converting enzyme (ACE) was synthesized. The effect of varying the antepenultimate amino acid residue in this series on the biological activity was studied. Introduction of Lys and Orn residues at the P1 position provided the most potent inhibitors, 25a and 25b (IC50: 3.5 and 4.9 x 10(-9) M, respectively), which exhibited an oral antihypertensive activity. This result suggests that basic amino acid residues at the P1 position play an important role in binding with the S1 subsite of ACE in this series. Oral antihypertensive activity of selected compounds was evaluated.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1989

Effects of coronary artery bypass surgery on regions showing persistent defects in thallium myocardial images.

The indications for revascularization surgery and its effects on myocardial regions showing persistent defects in thallium myocardial images are controversial. The effects of aortocoronary bypass surgery on myocardial perfusion and wall motion in the regions with persistent defects were evaluated in 47 patients with thallium-201 single photon emission computed tomography and left ventriculography. In areas showing persistent thallium defects preoperatively the rate of improvement of perfusion was only 24% by postoperative thallium imaging, and 57% by wall motion analysis. These results were significantly inferior to those of regions with transient defects, which were 84% and 82%, respectively. A persistent defect may not be a definitive marker of a non-viable scar, but the results of surgery on such regions were unsatisfactory. It is concluded, therefore, that revascuralization surgery in regions with persistent defects is not always recommended and that the indications for surgery should be individually determined with operative risk balanced against benefits.

Adult↗
PubMed1989

Sparganosis of the brain. Case report.

A rare case of cerebral sparganosis occurring in a 7-year-old boy is reported. Since his clinical symptoms fluctuated and diagnostic evaluation demonstrated multiple lesions, he was examined for a parasitic infection. Emphasis is placed on the difficulties involved in diagnosing cerebral sparganosis.

Brain Diseases↗
PubMed1989

Modifications of circadian cortisol rhythm by cyclic and continuous total enteral nutrition.

To clarify the relationship between the pattern of diet intake and the circadian adrenocortical rhythm, we measured plasma cortisol levels at 4-h intervals over a 24-h period in 18 patients who were in the vegetative state and had been receiving total enteral nutrition (TEN) for 4 weeks. One group of 6 patients was given a liquid diet intraduodenally and continuously throughout a day (continuous TEN), whereas the two other groups received their daily enteral feeding during a restricted time of day, either in the daytime from 0800 h to 2000 h (diurnal TEN, 6 patients) or in the nighttime from 2000 h to 0800 h (nocturnal TEN, 6 patients). In patients with diurnal TEN, there was a clear cortisol rhythm with a peak of 0800 h, whose pattern was quite similar to the well-established cortisol rhythm in normal subjects. Patients with nocturnal TEN also showed a cortisol rhythm, but the peak appeared at 1600 h. There was no appreciable difference in the amplitude of the rhythm between the two groups. Patients with continuous TEN did not show any consistent circadian cortisol rhythms. Plasma levels of glucose, insulin, and free fatty acids also showed circadian fluctuations corresponding to the pattern of diet infusion in the groups with diurnal and nocturnal TEN, and remained almost constant throughout a day in the group with continuous TEN. We conclude from these results that the timing of diet intake may have a synchronizing effect on the circadian cortisol rhythm in man, as it does in laboratory animals.

Aged↗
PubMed1989

Relationship between ventricular expression of atrial natriuretic polypeptide gene and hemodynamic parameter in old myocardial infarction.

Using Northern blot analysis and radioimmunoassay, we measured atrial natriuretic polypeptide (ANP) messenger RNA and ANP levels in the ventricle in patients with old myocardial infarction and investigated the relationship between ventricular ANP synthesis and hemodynamic parameters. Levels of ANP messenger RNA and ANP were markedly increased in the left ventricular aneurysm, and a positive correlation was observed between the ANP level in the left ventricular aneurysm and pulmonary capillary wedge pressure (r = 0.85, p less than 0.05). These findings indicate that ANP synthesis in the ventricle is increased in accordance with the severity of congestive heart failure.

Aged↗
PubMed1989

Antihypertensive mechanism of an angiotensin converting enzyme inhibitor, SA446, in dogs.

Antihypertensive mechanisms of SA446, an angiotensin converting enzyme (ACE) inhibitor, were examined in dogs. In isolated dog pulmonary artery, SA446 inhibited the contractile response to angiotensin (Ang) I, but did not affect the response to Ang II. In conscious dogs, SA446 (1 mg/kg po) remarkably inhibited the pressor response to Ang I between 1 and 6 hr after the administration. In normotensive dogs, SA446 (30 mg/kg po) significantly lowered the arterial pressure 3 hr after administration, which recovered at 24 hr, while plasma ACE activity was apparently inhibited even at 24 hr. The antihypertensive effect of SA446 (5 mg/kg po) was more potent in 2-kidney, 1-clip renal hypertensive dogs than in normotensive dogs. SA446 (10(-9) - 10(-7) M) inhibited the ACE activities in arteries isolated from dogs in concentration-dependent fashion. These results suggest that the antihypertensive effect of SA446 is related, at least partially, to inhibition of ACE in the vascular wall.

3-Mercaptopropionic Acid↗
PubMed1989

[Anatomical studies on a supernumerary tooth considered to be a successional tooth of the lower first molar].

The purpose of this study is to investigate features of the successional tooth of the lower first molar. Materials investigated in this study deal with a supernumerary tooth formed at the distolingual deep part to the lower right first molar of a male patient aged twenty-four. It was observed with binocular microscopy and under X-ray. The occlusal surface of it was observed with scanning electron microscopy. Horizontal ground sections of it were prepared and observed with polarizing microscopy, fluorescent microscopy, and scanning electron microscopy. It is thought that this supernumerary tooth is a true successional tooth of the lower first molar because it was formed at the distolingual deep part to the lower first molar and the fissure of it is Y-shaped and it has five cusps. It is considered that two impressions at buccal and distal surfaces of it isn't original hereditary features but was accidentally formed by pressures of mesial and distal roots of the lower first molar. The rough form of it has most resemblance to the lower second premolar and distal and lingual parts of it are smaller than that of the lower first molar. But fundamental features of the lower first molar are preserved in it. It is thought that the center of the molarization field of human lower successional teeth lies at the successional tooth of the lower first molar because the form of the occlusal surface of it is more complex and functional than those of the lower first and second premolars.

Adult↗
PubMed1989

[Influence of tooth extraction on postural stability].

A study was conducted to analyze how tooth extraction procedure would affect patient's physical equilibrium sensation, using the positional centric equilibrium measuring device. Forty-five health subjects, between the ages of 20 to 30, with no systemic nor equilibrium abnormalities were selected for this study. The results obtained were as follows. 1. No noticeable changes in the centric movement were observed during the postural change from a sitting to a standing position. 2. Centric movement was transiently increased immediately after the movement from a horizontal to standing position. The average arterial pressure was decreased immediately after the alteration in body posture, suggesting that changes in body posture may influence the controlling mechanism of BP. 3. Increases in the area and velocity of the centric movement were found immediately after and up to 10 minutes after, respectively, topical administration of the anesthetic. During this time span, no correlation found between centric movement changes and circulatory changes suggested that topical anesthesia might influence the recovery reflex via central nervous system. 4. The effect of the extraction procedure on the centric movement area and the anteroposterior centric movement speed lasted for 10 minutes after extraction. On the other hand, the increase in the velocity of bilateral centric movement as well as whole body centric movement was found up to a point immediately after extraction. No correlation was found between circulatory changes and centric movement changes. It therefore was assumed that the topical anesthesia affected the recovery reflex via central nervous system.

Adolescent↗
PubMed1989

Mechanism of action of 15-deoxyspergualin. I. Suppressive effect on the induction of alloreactive secondary cytotoxic T lymphocytes in vivo and in vitro.

The effects of 15-deoxyspergualin (DSG) and its derivative deoxymethylspergualin (MeDSG), which is more stable than DSG in solution, on the induction of alloreactive secondary cytotoxic T lymphocytes (CTL) in mice in vivo and in vitro were determined. Secondary CTL were generated in vivo or in vitro by injecting mice with mitomycin C (MMC)-treated allogenic tumour cells twice with a 1-week interval or by culturing spleen cells of alloantigen-primed mice with MMC-treated allogenic mouse spleen cells, respectively. DSG preferentially suppressed the generation of secondary CTL at the differentiation but not at the effector phase. DSG also suppressed the responsiveness of spleen cells to secondary antigen in a non-specific manner. MeDSG suppressed the in vitro induction of secondary CTL in a dose-dependent manner; however, it did not suppress the activity of CTL already induced. The inhibitory effect of MeDSG on CTL induction was totally abolished by exogenous recombinant murine interferon-gamma (IFN-gamma) and partly by interleukin-2 (IL-2), suggesting that suppressive mechanisms of MeDSG (DSG) may be mainly mediated by the inability of lymphocytes to produce IFN-gamma or by impairment of an unknown cascade(s) reconstituted by IFN-gamma.

Animals↗
PubMed1989

[Pulsatile assistance for profoundly hypothermic circulatory arrest, low-flow perfusion, and moderate-flow perfusion: comparative study of brain tissue pH, PO2, and PCO2].

The pH, oxygen tension, and carbon dioxide tension of canine brain tissue were experimentally examined during profoundly hypothermic cardiopulmonary bypass with and without pulsatile assistance. After core cooling, a 60-minute of circulatory arrest was performed in group 1 (n = 16), a 120-minute of low-flow perfusion (25 ml/kg/min) in group 2 (n = 16), and 120 minute of moderate-flow perfusion (50 ml/kg/min) in group 3 (n = 16). The core rewarming was done to the temperature above 32 degrees C. Each group was divided into two subgroups with and without pulsatile assistance (subgroup-p; n = 8, subgroup-c; n = 8). In group 1, progressive brain tissue acidosis and hypercapnea were recovered by use of pulsatile assistance. In group 2, brain tissue acidosis and hypercapnea were recovered completely with pulsatile assistance, but incompletely without it. In group 3, mild acidosis and hypercapnea were eliminated with pulsatile assistance. Brain tissue hypoxia was severe in group 1, slight in group 2, but not found in group 3. We conclude that a pulsatile assistance provides brain protection at any flow-ratio, and that the less flow-ratio and the longer perfusion period will make the pulsatile assistance the more necessary.

Animals↗
PubMed1989

[A case of complete rupture of the righ TMJ disc].

A case of complete rupture of the right TMJ disc was described. A 43 year old woman visited our hospital with the chief complaint of a mild pain in the right TMJ. Initially, a conservative treatment using the occlusal splint (condylar repositioning appliance) was carried out. This was because she had reciprocal clicking of the right TMJ which had occurred not long before and it seemed that the symptoms were due to the trouble with the disc. In spite of this treatment, for 6 months no improvement was obtained and the reciprocal clicking changed into crepitation. Moreover the double contrast arthrotomographic image indicated a perforation or a wide rupture of the disc, and deformities of the articular bone. Then a right TMJ osteoarthrosis with wide (complete) disc rupture was diagnosed, and a discectomy was performed. The symptoms were greatly reduced by this treatment. It was conceivable that the steroid which she had used for a long time to treat bronchial asthma caused a remarkable inhibition of the tissue repairing, and an internal derangement of the TMJ rapidly progressed to osteoarthrosis.

Adrenal Cortex Hormones↗
PubMed1989

[Aortic aneurysm associated with coarctation of the aorta].

An 8-year-old female of coarctation of the aorta associated with thoracic aortic aneurysm is reported. Under cardiopulmonary bypass, a 7 cm section of the aorta containing the aneurysm and coarctation was resected and replaced by a 16 mm woven Dacron tube. The postoperative recovery was complicated by chylothorax treated by thoracic aspiration. She is doing well 3 months after the operation. Histologic sections of the resected portions of the thoracic aorta revealed intimal hyperplasia, medial fibrosis and decrease of elastic fibers, especially in the aneurysm.

Aorta, Thoracic↗