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S Nishimura

Publications and source records attributed to S Nishimura.

At least 613 records · Page 34Linked to original sources
PubMed1989

[Development of a new quantitative analysis for thallium myocardial SPECT images--quantitative STEREO-VIEW method and evaluation of its clinical usefulness].

We have developed a three-dimensional quantitative display method, Quantitative STEREO-VIEW method (STEREO-VIEW method), for analysis of thallium (Tl) myocardial SPECT images and have evaluated its clinical usefulness. SPECT data were obtained immediately and 4 hours after the exercise, and contour lines for outer edges of left ventricular (LV) myocardium were detected from 10 slices of short axial images in delayed scan. LV wall was divided into 510 segments by dividing each slice into 51 sectors and LV myocardium was three-dimensionally reconstructed. Mean Tl counts, %T1 uptake and washout rate (WR) of each segment were calculated and these values were represented such as infarcted area display, redistribution display and WR display on STEREO-VIEW. Furthermore, extent index (EI), severity index (SI) and intensity index (II) were defined to express the degree of perfusion abnormality using WR value of each segment. In the 25 patients with coronary revascularization, improving rate of these indices correlated well with that of double product significantly. STEREO-VIEW method resembled in the original shape of left ventricle of each patient, so STEREO-VIEW method has made it easier to discriminate the accurate extent of ischemic lesion. In addition, EI, SI and II using WR were good indices for coronary perfusion and these were thought to be useful on clinical study.

Aged↗
PubMed1988

Codon and amino-acid specificities of a transfer RNA are both converted by a single post-transcriptional modification.

An Escherichia coli isoleucine transfer RNA specific for the codon AUA (tRNA(2Ile) or tRNA(minorIle] has a novel modified nucleoside, lysidine in the first position of the anticodon (position 34), which is essential for the specific recognition of the codon AUA. We isolated the gene for tRNA(2Ile) (ileX) and found that the anticodon is CAT, which is characteristic of the methionine tRNA gene. Replacement of L(34) of tRNA(2Ile) molecule enzymatically with unmodified C(34) resulted in a marked reduction of the isoleucine-accepting activity and, surprisingly, in the appearance of methionine-accepting activity. Thus, both the codon and amino-acid specificity of this tRNA are converted by a single post-transcriptional modification of the first position of the anticodon during tRNA maturation.

Anticodon↗
PubMed1988

A novel lysine-substituted nucleoside in the first position of the anticodon of minor isoleucine tRNA from Escherichia coli.

A minor species of isoleucine tRNA (tRNA(minor Ile)) specific to the codon AUA has been isolated from Escherichia coli B and a modified nucleoside N+ has been found in the first position of the anticodon (Harada, F., and Nishimura, S. (1974) Biochemistry 13, 300-307). In the present study, tRNA(minor Ile)) was purified from E. coli A19, and nucleoside N+ was prepared, by high-performance liquid chromatography, in an amount (0.6) A260 units) sufficient for the determination of chemical structures. By 400 MHz 1H NMR analysis, nucleoside N+ was found to have a pyrimidine moiety and a lysine moiety, the epsilon amino group of which was involved in the linkage between these two moieties. From the NMR analysis together with mass spectrometry, the structure of nucleoside N+ was determined as 4-amino-2-(N6-lysino)-1-(beta-D-ribofuranosyl)pyrimidinium ("lysidine"), which was confirmed by chemical synthesis. Lysidine is a novel type of modified cytidine with a lysine moiety and has one positive charge. Probably because of such a unique structure, lysidine in the first position of anticodon recognizes adenosine but not guanosine in the third position of codon.

Anticodon↗
PubMed1988

Simple enzyme immunoassay methods for recombinant human tumor necrosis factor alpha and its antibodies using a bacterial cell wall carrier.

We have developed simple methods for measuring recombinant human tumor necrosis factor alpha (rHu-TNF alpha) and antibodies to rHu-TNF alpha in the sera of animals intravenously injected with rHu-TNF alpha. rHu-TNF alpha was measured by a competitive binding enzyme immunoassay (C-EIA) using standard rHu-TNF alpha, beta-galactosidase labeled rHu-TNF alpha as enzyme-labeled antigen (E-Ag) and anti-rabbit IgG goat immunoglobulins coupled to bacterial cell walls (insolubilized second antibody). In contrast, anti-rHu-TNF alpha antibodies were measured by a sandwich EIA (S-EIA) using purified anti-rHu-TNF alpha rabbit IgG as standard, beta-galactosidase labeled rHu-TNF alpha as E-Ag, and rHu-TNF alpha coupled to bacterial cell walls as insolubilized antigen. C-EIA permits the determination of serum rHu-TNF alpha within the range of 2-150 U/ml (about 0.7-52 ng/ml) with a CV of below 7.6% and 99% recovery. S-EIA permits the determination of anti-rHu-TNF alpha antibodies within the range of 70-1000 ng/ml with a CV of less than 4% and 94.8-106.9% recovery.

Animals↗
PubMed1988

Crystallization and preliminary crystallographic data of a truncated derivative from the human c-Ha-ras protein.

A truncated derivative of the human c-Ha-ras protein has been crystallized from polyethylene glycol 6000 solution by a vapour diffusion technique. The rectangular prism diffracts X-rays to at least 2.5 A resolution (1 A = 0.1 nm). The unit cell is monoclinic, space group P21, with unit cell parameters of a = 50.2 A, b = 110.9 A, c = 36.4 A, beta = 97.2 degrees. The unit cell contains four molecules.

Crystallization↗
PubMed1988

Crystallization of human c-H-ras oncogene products.

There is compelling evidence that cancer develops as a consequence of genetic changes (probably multiple) in some members of a selected set of cellular genes. DNA isolated from a variety of tumors, but not normal tissues, possesses the ability to malignantly transform non-tumorigenic cells. Many oncogenes responsible for such transformation have been isolated from transformed cell lines and animal and human tumors induced spontaneously, by virus, by chemical, or by radiation. The most commonly found transforming genes isolated from human tumor cells by DNA transfection assay are the ras gene family (c-H-ras, c-K-ras and N-ras). We report crystallization of several human c-H-ras oncogene proteins.

Crystallization↗
PubMed1988

Three-dimensional structure of an oncogene protein: catalytic domain of human c-H-ras p21.

The crystal structure at 2.7 A resolution of the normal human c-H-ras oncogene protein lacking a flexible carboxyl-terminal 18 residue reveals that the protein consists of a six-stranded beta sheet, four alpha helices, and nine connecting loops. Four loops are involved in interactions with bound guanosine diphosphate: one with the phosphates, another with the ribose, and two with the guanine base. Most of the transforming proteins (in vivo and in vitro) have single amino acid substitutions at one of a few key positions in three of these four loops plus one additional loop. The biological functions of the remaining five loops and other exposed regions are at present unknown. However, one loop corresponds to the binding site for a neutralizing monoclonal antibody and another to a putative "effector region"; mutations in the latter region do not alter guanine nucleotide binding or guanosine triphosphatase activity but they do reduce the transforming activity of activated proteins. The data provide a structural basis for understanding the known biochemical properties of normal as well as activated ras oncogene proteins and indicate additional regions in the molecule that may possibly participate in other cellular functions.

Amino Acid Sequence↗
PubMed1988

Microsurgical removal of intramedullary spinal cord tumours: report of 22 cases.

The management of patients with intramedullary spinal cord tumours is controversial. The authors have treated these tumours in accordance with the principles of radical resection, using microsurgical techniques. There have been 22 cases of intramedullary spinal cord tumours (4 astrocytomas, 3 glioblastoma multiformes, 5 ependymomas, 7 haemangioblastomas, 1 dermoid, 1 lipoma and 1 schwannoma) thus treated at our department during the past 13 years. Sixteen were adults and six were children. The early and late results of their surgical treatment have been analyzed, with follow-up periods ranging from 10 months to 12 years. Of the 22 patients, total removal was performed in 16, subtotal removal in 5 and biopsy in 1. Guidetti's criteria were adopted in assessing the results of surgery. Long-term results were as follows: 8 very good, 5 good, 3 fair, 3 poor and 3 deceased. The 3 latter cases were glioblastoma multiformes. Gross total removal of intramedullary tumours is technically feasible and compatible with neurological recovery. Since the majority of intramedullary tumours are benign and their course may span not only years but decades, long-term follow-up is essential.

Adolescent↗
PubMed1988

MR appearance of Rathke's cleft cysts.

Two of three patients who proved to have symptomatic Rathke's cleft cysts presented with visual field deficit and all with diabetes insipidus. CT showed intra- and suprasellar cystic low density lesions with ring enhancement. MR showed intra- and suprasellar masses. On the T1-weighted images two of the three had hyperintense portions similar to fat and the other a hyperintense portion similar to white matter within the cysts. These portions were isointense to brain on the T2-weighted images in all cases. This characteristic intensity on MR images provides differentiation from cystic pituitary adenomas and cystic craniopharyngiomas, and leads to correct diagnosis of Rathke's cleft cyst.

Adult↗
PubMed1988

Coronary artery spasm during coronary artery bypass surgery: its diagnosis, treatment and prevention.

Between 1982 and 1983, we experienced four cases of hemodynamic collapse accompanied by an ST-segment depression in the ECG lead II, shortly after the cessation of cardiopulmonary bypass. The bypass graft flows monitored in these patients during the hemodynamic collapse episodes were remarkably low. In three cases, nitroglycerin (0.5-1 mg) was injected directly into the vein graft, which increased the graft flow suddenly, returned the ST-segment to the baseline, and improved the circulatory condition. Since 1984, however, diltiazem has been used in the cardioplegic solution and postoperative drip infusion. Due to the introduction of this drug, coronary artery spasm has not been seen in any of our patients since. These findings show that the monitoring of ST-segment changes and bypass graft flows are useful in the early diagnosis of coronary artery spasm after myocardial revascularization. Direct infusion of nitroglycerin into the vein graft is effective for the treatment of spasm, while diltiazem is useful in the prevention of coronary artery spasm incidental to myocardial revascularization.

Coronary Artery Bypass↗
PubMed1988

Selective inhibition of formation of suppressor glutamine tRNA in Moloney murine leukemia virus-infected NIH-3T3 cells by Avarol.

Avarol is a sesquiterpenoid hydroquinone, which displays no inhibitory potencies on mammalian DNA polymerases alpha, beta, and gamma, on mammalian RNA polymerases I, II, and III, or on reverse transcriptases from Moloney murine leukemia virus (Mo-MuLV) and from HIV. For a further elucidation of the antiviral effect of Avarol, we used NIH-3T3 cells infected with Mo-MuLV as a model system. The results show that in uninfected NIH-3T3 cells Avarol (i) causes a 50% reduction of the growth rate only at the high concentration of 29.6 microM and (ii) is accumulated in the cytoplasm close to the nucleus. At the much lower concentrations of 1-3 microM, Avarol causes an almost complete inhibition of viral progeny release. Moreover, it is shown that at 3 microM Avarol, the increase of the Mo-MuLV-induced UAG suppressor glutamine tRNA (tRNA(UmUGGln) was reduced to the normal level. Dot blot hybridization studies revealed that Avarol displays no inhibitory activity on cellular and viral mRNA synthesis. Taking the processing pathway of viral polyprotein Pr180gag,pol to p80 (reverse transcriptase) as an example, our Western blotting experiments showed that the final maturation process, conversion of p110 to p80, is inhibited in Avarol-treated cells. From these data we conclude that Avarol prevents the suppression of the UAG termination codon at the gag-pol junction of the retroviral genome. The functional consequence of this event is very likely an inhibition of the readthrough of the retroviral protease gene which overlaps the pol and gag genes, resulting in the reduction of the protease synthesis which is necessary for the viral proliferation.

Animals↗
PubMed1988

A gigantic neurilemoma originating in the pterygopalatine fossa. Case report.

A 7-year-old girl complained of gradually progressing right nasal obstruction, right exophthalmos, and deterioration of right visual acuity. Computed tomography scanning showed a large mass originating in the pterygopalatine fossa and extending to both the pterygomaxillary fossa and the orbital apex on the right side. The tumor was totally removed via the orbitozygomatic infratemporal approach. The literature is reviewed and the operative approach is discussed.

Cerebral Angiography↗
PubMed1988

A combined retroauricular and preauricular transpetrosal-transtentorial approach to clivus meningiomas.

A combined retroauricular and preauricular transpetrosal-transtentorial approach is described for the resection of meningiomas arising from the clivus. Via radical mastoidectomy the sigmoid sinus is exposed down to the jugular bulb, and via the transmastoideal-subtemporal approach the retroauricular petrosal bone, 1 cm in depth from the petrosal ridge, and the roof of the internal auditory meatus are removed, the middle ear and fallopian canal being left intact. Additionally, via a transzygomatic-subtemporal approach the preauricular petrosal bone is removed anteriorly up to the petrosal tip and laterally as far as the petrosal portion of the internal carotid artery, while the cochlea is preserved. By this means, the triangular portion of the posterior petrosal dura mater, delimited by the superior petrosal sinus, inferior petrosal sinus, and sigmoid sinus, is well exposed extradurally. By opening the subtemporal and posterior petrosal dura mater, in combination with a tentoriotomy, adequate exposure of the basilar artery, vertebral arteries, ventral and lateral portions of the brainstem, and cranial nerves is achieved with minimal retraction of the temporal lobe and cerebellum.

Cranial Fossa, Posterior↗
PubMed1988

Size of breast cancer on ultrasonography, cut-surface of resected specimen, and palpation.

In the period from January 1985 to May 1987, 68 patients with palpable breast cancers were studied to compare the size on ultrasonography with the size of the cut-surface of the resected specimen. Both the width (mediolateral size) and height (size in depth) were delineated as smaller on ultrasonography than on the cut-surface of resected specimens. The difference in size between ultrasonography and resected specimen was greater for the width than for the height. These results can explain why breast cancer has a greater ratio of height to width on ultrasonography. The ratio of the width on palpation to that on ultrasonography was also evaluated. These ratios proved to be useful in differentiating breast cancer from benign lesions.

Breast Neoplasms↗
PubMed1988

Neurophysiological and neuropathological studies in two children with unusual form of multiple system degeneration: evidence for cerebellar and brainstem involvement.

Comparative neurophysiological and neuropathological studies were performed in two children who were found as a very rare multiple system degeneration (MSD) in brainstem and cerebellum. One young child suffered from both multiple system and retinal degeneration and another child had widespread multiple system degeneration associated with lipoprotein disorder and liver cirrhosis. The results of the neurophysiological studies indicated dysfunction of the brainstem and the peripheral nerves and were well correlated with the clinical course. CT studies showed progressive cerebellar atrophy. Since serial neurophysiological and CT studies were compatible with the neuropathological findings, the combination of these examinations seems to be quite valuable for understanding the pathogenesis and monitoring the progression of MSD in childhood.

Brain Diseases↗