Biomedical subjects

S Higashi

Publications and source records attributed to S Higashi.

At least 145 records · Page 8Linked to original sources

PubMed1992

Three-dimensional observations of accessory canals in mature and developing rat molar teeth.

The structure, distribution and formation of accessory canals in the developing and mature molar teeth of rat mandibular jaws were investigated with scanning electron microscopy and with three-dimensional image analysis using serial light-microscopic sections. In the initial stage of the accessory canal formation, most of the canals appeared in the gaps of the epithelial root sheaths formed by their approaching each other in the initial stage of the root formation. However, some of the canals appeared in the slits which may be formed by the destruction of the epithelial root sheath in the root apex regions. When the gaps and slits were invaded by blood vessels, the regions surrounding the vessels did not mineralize but became accessory canals. Usually, an accessory canal with one blood vessel connected the periodontal ligament to the dental pulp; however, in some cases, the canals were broken off midway following the destruction of the vessels.

Animals↗

PubMed1992

Cerebral arteriovenous malformations in a pregnancy with twins: case report.

The natural course of cerebral arteriovenous malformations during pregnancy is not well known. An inoperable cerebral arteriovenous malformation was diagnosed by angiography, computed tomography, and magnetic resonance imaging before pregnancy and followed by magnetic resonance imaging during pregnancy. No significant changes were detected in the size of the cerebral arteriovenous malformation during pregnancy, and healthy twins were born by cesarean section.

Cerebral Angiography↗

PubMed1992

Scanning electron microscopic observations of the periodontal ligament fibers and cells in rat molar teeth.

The periodontal ligament of rat molar teeth was observed with scanning electron microscopy (SEM) using two different methods: NaOH maceration and KOH-collagenase treatments. Rat jaws with molar teeth were fixed, demineralized with 10% EDTA, and cut into several pieces. After maceration with 5% NaOH for 5 days at room temperature, the cellular elements were completely removed and the periodontal ligament fibers appeared as bundles of collagen fibrils. The fibers branched and anastomosed but did not spread fibrils randomly. In some regions near the alveolar bone, collagen fibrils circularly binding the fibers were found. When treated with 30% KOH for 7 to 10 minutes at 60 degrees C and with 0.1% collagenase, the periodontal ligament fibers were removed and the cells appeared as spindle and stellate shapes, and combined with the irregular cell processes of each other. Thus, the interaction between the periodontal ligament fibers and cells were three-dimensionally visualized by using the two different methods.

Animals↗

PubMed1992

[A case of SSPE presenting visual disturbance and serial MRI study].

A case of subacute sclerosing panencephalitis (SSPE) was reported. The patient was a 16-year-old boy and he initially developed visual disturbance. His neurologic symptoms were myoclonus, dementia, and visual disturbance which was rare as an initial symptom in SSPE. Fundoscopy revealed bilateral pole chorioretinitis and macular degeneration. Serial MRI study demonstrated the lesions in the brain and right eye ball. The distribution varied as time went on. T2-weighted MR images showed the lesions more clearly than T1-weighted MR images. In this case dementia was marked but the lesions in the cerebrum on the MR images were considerably smaller than expected. Although MR image is useful to show the lesions, the discrepancy between clinical signs and MR images may be present in the early stage in SSPE.

Adolescent↗

PubMed1992

[A case of encephalitis with MRI abnormalities localized in the bilateral amygdala and hippocampus].

We report a patient with encephalitis who showed anterograde and retrograde amnesia with MRI abnormalities localized in the bilateral amygdala (AM) and hippocampus (HIPP). A 25-year-old man suddenly experienced a generalized tonic-clonic seizure (GTCS). He was admitted because of increasing lethargy with two further GTCSs during the following 6 days. The patient had high fever, and neurological examination revealed somnolence, disorientation, amnesia, and nuchal stiffness. MRI revealed bilateral symmetrical abnormalities localized in the AM and HIPP, which showed low intensity on T1-weighted images and high intensity on T2-weighted images. Cerebrospinal fluid examination showed a mildly elevated cell count. We suspected herpes simplex virus type I encephalitis and began treatment with acyclovir. After the patient regained a clear consciousness, his antero- and retrograde amnesia continued for several months. The MRI abnormality became less distinct with the improvement of amnesia. We consider that the MRI abnormality was indicative of inflammation and edema, and that the lesion in the AM and HIPP had induced the amnesia.

Acyclovir↗

PubMed1992

[67Ga scintigram and MRI in malignant bone tumors and malignant soft tissue tumors].

We have analyzed the characteristics of 67Ga scintigram and MRI in 11 malignant bone tumors and 11 malignant soft tissue tumors. Osteosarcoma showed a high accumulation in 67Ga scintigram and low signal intensity in T1 weighted image. T2 weighted image were not characteristic. Chondrosarcoma showed medium 67Ga accumulation and low signal in T1 weighted image and high signal in T2 weighted image. Ewing sarcoma showed low accumulation in 67Ga scan and medium intensity in MRI. Malignant soft tissue tumors showed rather low 67Ga accumulation compared with malignant bone tumors. Malignant fibrous histiocytoma showed medium accumulation of 67Ga, low signal in T1 weighted image and high signal in T2 weighted image. Liposarcoma showed low 67Ga accumulation and medium signal in T1 weighted image and high signal in T2 weighted image. To summarize these characteristics, three dimensional display is demonstrated.

Bone Neoplasms↗

PubMed1991

Synapses formed by ectopic corticofugal axons: an electron microscopic study of crossed corticorubral projections in kittens.

The corticorubral projections in newborn kittens are bilateral, while the projections are unilateral in adults. We addressed the question whether or not the crossed corticorubral projection in kitten forms synaptic contacts in the red nucleus. The neurons in the sensorimotor cortex of the kitten were labeled by Phaseolus vulgaris-leucoagglutinin or biocytin. Electron microscopic observations revealed that corticofugal axons form synapses both in the contralateral and the ipsilateral red nucleus; most of them were on small postsynaptic profiles, possibly dendritic spines or distal dendrites.

Animals↗

PubMed1991

The cis/trans isomerization of the double bond of a fatty acid as a strategy for adaptation to changes in ambient temperature in the psychrophilic bacterium, Vibrio sp. strain ABE-1.

The major phospholipid, phosphatidylethanolamine (PE), of Vibrio sp. strain ABE-1 contains a unique trans-unsaturated fatty acid, 9-trans-hexadecenoic acid (16:1(9t], at the sn-2 position of the glycerol moiety. The major molecular species of PE that contain 16:1(9t) at the sn-2 position have either 9-cis-hexadecenoic acid (16:1(9c] or hexadecanoic acid (16:0) at the sn-1 position. The transition temperatures of the liquid-crystal to the gel phase of 16:1(9c)/16:1(9t)-PE and 16:0/16:1(9t)-PE were -3 degrees C and 38 degrees C, respectively, temperatures that were 31 degrees C and 18 degrees C higher than the corresponding temperatures for 16:1(9c)/16:1(9c)-PE and 16:0/16:1(9c)-PE. The proportion of 16:1(9c)/16:1(9t)-PE and 16:0/16:1(9t)-PE increased significantly in cells grown at 20 degrees C over that in cells grown at 5 degrees C. When cells grown at 5 degrees C were incubated at 20 degrees C in the presence of cerulenin, an inhibitor of the synthesis de novo of fatty acids, the level of 16:1(9t) increased almost in parallel with a concomitant decrease in the level of 16:1(9c) at the sn-2 position. These results suggest that 16:1(9c) is converted to 16:1(9t) by the cis/trans isomerization of the double bond in the fatty acid. This conversion is discussed as a possible strategy for adaptation by bacteria to changes in temperature.

Adaptation, Physiological↗

PubMed1991

Lesion-induced establishment of the crossed corticorubral projections in kittens is associated with axonal proliferation and topographic refinement.

The aberrant crossed corticorubral projection of the cat, which is very weak compared to the uncrossed one at about 1 month postnatal, becomes pronounced following unilateral lesions of the sensorimotor cortex. In order to determine whether or not terminal proliferation of pre-existing axons underlie this enlargement, the morphological changes of the crossed axons were examined, using the anterograde tracer Phaseolus vulgar- is leukoagglutinin (PHA-L). The crossed corticorubral axons in normal kittens were mostly simple in morphology with infrequent branching and did not often exhibit growth-cone-like axonal endings at 1 month postnatal. Two to 5 days after unilateral lesions of the sensorimotor cortex placed at this age, the axons were as simple as those in normal animals but ended in growth cones more frequently. Seven to 10 days post-lesion, the axons often bore side-branches which ended in growth cones. Two to 3 weeks post-lesion axons with sprays of finger-like fine sprouts occurred throughout the projection zone. There was no clear topography for the crossed projection in normal animals, but at 1-2 weeks post-lesion the axons started to show a certain amount of localization in the regions of the red nucleus which corresponded to the densely innervated region on the ipsilateral side. The topography of the crossed projections roughly mirrors that of the ipsilateral projection at about 1 month post-lesion. Thus, the lesions of the sensorimotor cortex induce substantial growth and proliferation of the crossed corticorubral axons. The post-lesion changes in axonal morphology and topographic refinement are reminiscent of developmental events. It is likely that the lesions permit the crossed axons, which normally fail to develop, to develop like the uncrossed ones.

Aging↗

PubMed1991

SPECT evaluation of brain perfusion reserve by the acetazolamide test using Tc-99m HMPAO.

This report describes a new approach to the evaluation of brain perfusion reserve using Tc-99m HMPAO SPECT. Consecutive brain Tc-99m HMPAO SPECT studies before and after acetazolamide (Diamox) administration were performed within 30 minutes on 19 patients with significant vascular occlusive lesions. Thirteen patients showed decreased perfusion reserve and four patients maintained perfusion reserve in the affected vascular territories after Diamox administration, providing additional information to baseline Tc-99m HMPAO SPECT in 17 (89%) patients. Although flow augmentation post-Diamox was underestimated, possibly due to the nonproportionality of Tc-99m HMPAO activity to true blood flow, significant changes in the brain perfusion pattern were both visually and quantitatively determined using an image subtraction technique. This consecutive Tc-99m HMPAO SPECT technique seems to be of practical use for the evaluation of brain perfusion reserve and for the improvement of the sensitivity of detecting pathologic areas.

Acetazolamide↗

PubMed1991

Effect of alcohol ingestion on carcinogenesis by synthetic estrogen and progestin in the rat liver.

We examined the effect of alcohol ingestion on hepatocarcinogenesis induced by oral administration of synthetic female hormones, 0.075 mg of ethynylestradiol (EE) and 6.0 mg of norethindrone acetate (NA), every day for 12 months in female Wistar rats. Administration of 10% ethanol in drinking water for 5 days a week every week resulted in the development of hepatocellular carcinoma (HCC) in 38.4% of the hormone-treated rats at 12 months, which is approximately 5 times the incidence of HCC observed following EE and NA treatment alone. The number of hyperplastic nodules was significantly higher than the number observed in the case of EE and NA treatment alone after 4 months of the experimental period. The additional alcohol treatment also increased the value of unoccupied nuclear estrogen receptors (ERn) at months 6 and 8 of the experimental period, and increased the value of total ERn in the rat liver after 6 months of the experimental period. This indicates that additional alcohol treatment may increase occupied ERn (estrogen-ER complex) in the rat liver. A 32P-postlabeling analysis of liver DNA revealed that the maximum number of extra spots consisting of modified nucleotides induced by EE and NA appeared earlier when the additional alcohol treatment was imposed. Consequently, alcohol affects the hepatocarcinogenesis by EE and NA, promoting not only the change in kinetics of ER, but also DNA adduct formation induced by EE and NA in the rat liver.

Alanine Transaminase↗

PubMed1991

Morphological study on the 'seams' in the multiroot formation of rat molar teeth.

'Seams' of the root furcation with multiroots in rat molar teeth, termed by Lester and Boyde, were investigated using transmitted light and scanning electron microscopy in the formation process. The seam was formed in the junctional line of Hertwig's epithelial root sheaths. The seam formation will be classified into three types in the initial stage based on the position of the epithelial root sheaths approaching each other: (1) the close junction or the very narrow slit or gap formed between them, (2) the clear gap containing mesenchymal cells and (3) the gap containing one blood vessel. When the roots were formed, the seam was formed as follows: (1) the slight ridge composed of the cellular cementum, (2) the proliferation or the depression in the dentine formation and (3) the accessory or lateral canal of the root. These structures were variously combined with each other into one seam, although the slight ridge was very common.

Animals↗

PubMed1991

Structural and distribution patterns of surface 'prismless' enamel in human permanent teeth.

Using human permanent teeth, structural and distribution patterns of the surface 'prismless' enamel with the occasional presence of indistinct and/or stunted prism structures were investigated by scanning electron microscopy. The 'prismless' enamel was classified into three shapes: step-like, occurring in mid-coronal enamel; band-like, frequently seen in occlusal and fissure enamel, and island-like, found in occlusal and cuspal-coronal enamel. These three 'prismless' shapes were formed by two structural patterns. One was determined by prisms which gradually changed into 'prismless' structures via indistinct and stunted prisms (prism-dependent; P type), and another, probably a variance of the P type, was characterized by prisms which abruptly changed into 'prismless' structures on the incremental lines of Retzius or the fine laminated striations (Retzius-dependent; R type). The P type pattern clearly forming the band and island-like shapes was found in occlusal and cuspal-coronal enamel, whereas the R type pattern forming some of the band-like shapes as well as the step-like shapes might be observed in almost all surface enamel.

Adolescent↗

PubMed1991

[Effects of intraarterial infusion chemotherapy on liver function in patients with hepatocellular carcinoma].

Periodic infusion chemotherapy from the reservoir implanted by direct arterial puncture (Seldinger method) was performed in 21 cases of hepatocellular carcinoma. The effectiveness of treatment in terms of efficacy and liver function in about 12 patients who survived more than 6 months was investigated. Owing to the progressive liver atrophy and liver dysfunction with ascites, some cases had to delay infusion treatment. Thus, it is necessary to check liver function regularly.

Adult↗

PubMed1991

[Evaluation of brain perfusion SPECT imaging using 99mTc-ECD].

Fundamental and clinical evaluation was performed on 99mTc-ECD, a new agent for brain perfusion SPECT. Radiochemical purity reaches a plateau of approximately 98% at 30 min after reconstitution and remains stable up to 24 hours later. A biodistribution study showed approximately 5% injected dose in the brain, very slow brain washout of 5.6% per hour on the average, and rapid washout from the other organ mainly through the urinary system. Brain ECD distribution was determined within 2 min postinjection and remained stable for up to 1 hour. Three hours later, slight but significant changes in brain distribution were observed, that were relative reduction of cerebral cortical activity and gray to white matter activity ratio, and relative elevation of white matter and thalamic activities. Comparative studies of ECD images with IMP and HMPAO images revealed that radioactivity contrast between affected and unaffected areas was less prominent in ECD than in IMP in cerebral and cerebellar cortical lesions, more prominent in ECD than in IMP in striatal and thalamic lesions, and somewhat more prominent in ECD than in HMPAO in both lesions. Imaging around 1 hour postinjection seems to be more appropriate than immediate postinjection imaging because of the clearance of the extracranial radioactivity and somewhat better radioactivity contrast between affected and unaffected areas.

Adult↗

PubMed1991

[Clinico-pathological comparative study between brainstem encephalitis of Iizuka type and neuro-Behçet's disease].

We experienced one necropsy case of brainstem encephalitis of Iizuka type (BSE) and one necropsy case of the brain-stem syndrome (BSS) of typical neuro-Behçet's disease, and compared them clinically and neuropathologically. Clinically both of these cases showed chronic progressive mental disturbance, pseudobulbar paresis, spastic tetraparesis, cerebrospinal fluid pleocytosis, increased protein, and brainstem atrophy observed by X-CT. Neuropathologically, irregular, boundary-indistinct demyelinating lesions and obsolete softening lesions were sporadically found, associated with perivascular lymphocytic infiltration and gliosis centering on the brainstem. In this way, both cases were similar in many points except for the presence or absence of cutaneo-muco-ocular signs specific for Behçet's disease. Also BSE and BSS reports in the literature showed that both diseases were similar not only in clinical findings consisting of mental disturbance and brainstem signs but also in neuropathological findings with similar topographical distribution of the same histopathological changes, including the variations and diversity of these characteristics. Especially of much interest is their similarity in characteristic mental disturbance. In discriminating BSE from multiple sclerosis and other diseases with exclusive involvement of the brainstem, it is important to understand their clinical characteristics. The characteristic mental disturbance includes damage to memory and sentiment, a change in personality, and lowering in spontaneity, but calculation ability and orientation are comparatively preserved. Of course the similarity in clinical and neuropathological findings does not necessarily mean the identical etiopathogenesis. However, it is possible to consider that neuro-Behçet's disease (syndrome) may form a wide spectrum with BSE and typical neuro-Behçet's disease at the both ends, regarding the time and spatial diversity of the appearance of cutaneo-muco-ocular signs.

Atrophy↗

PubMed1991

[Occlusion of the right pulmonary artery due to acute dissecting aortic aneurysm].

A 58-year-old female was admitted with an abrupt onset of chest and back pain. The CT scan of the chest showed aortic dissection of the ascending aorta and proximal aortic arch, but the false lumen of the aortic dissection had already been occluded by a blood clot. After admission, she complained of chest pain with hemoptysis and presented facial edema and the distention of the neck veins. The pulmonary angiogram showed complete occlusion of the right pulmonary artery at the proximal segment. These findings were interpreted as pulmonary embolism. She was treated with intravenous heparin and urokinase, but these treatments did not demonstrate any improvement. She underwent a surgical exploration on the fourth hospital day. During surgery, the right pulmonary artery was discovered to be compressed and occluded by the large dissecting aneurysm of the ascending aorta. In addition, hematoma was seen between the right pulmonary artery. The ascending aorta and pulmonary trunk, which was injured in the operative procedure, were replaced with an artificial graft successfully. Postoperative pulmonary angiogram showed no stenosis of right pulmonary artery. The occlusion of the pulmonary artery by an acute dissecting aneurysm is an extremely rare complication and it is often wrongly diagnosed as pulmonary embolism. In such cases, the correct diagnosis and prompt surgical treatment is essential and antithrombolytic and anticoagulant therapy should be avoided.

Acute Disease↗

PubMed1990

Postnatal development of crossed and uncrossed corticorubral projections in kitten: a PHA-L study.

Morphological changes in individual corticorubral fibers and the pattern of crossed and uncrossed corticorubral projections were studied during the postnatal development of cats in order to understand cellular mechanisms for restriction of corticorubral projections with development. The anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L) was injected into restricted areas of the pericruciate cortex in kittens and PHA-L-labeled axons in the red nucleus were examined at postnatal days (PND) 7-73. In accordance with our previous study (Murakami and Higashi, Brain Res. 1988; 447:98-108), a crossed corticorubral projection was observed in addition to the uncrossed one in every experimental animal. During the early period of development (PND 7-8), swellings of irregular shape were observed along the entire course of the axons and they were often interconnected with extremely fine axonal segments. These axons bifurcated only infrequently and often ended as growth cones. These features were common to both uncrossed and crossed corticorubral axons. At later stages of development (PND 28 or later), the total number of swellings decreased and axonal swellings with smooth contours became dominant. A quantitative examination of axonal branches indicated that axons on the ipsilateral side branch occurred more frequently at later stages of development. However, there was no substantial change in branching frequency for the crossed corticorubral fibers during development. In parallel with morphological changes in individual axons, the crossed projection that was initially relatively abundant was reduced during development. Since a PHA-L injection can be confined to a small region of cortex, topographic projections can easily be detected. At PND 7-8 there was no well-defined topographic order in the ipsilateral corticorubral projection. Adult-like topography was first discernible at PND 13. These observations suggest that the unilateral uncrossed corticorubral projection in the adult cat is achieved at least in part by the formation of axonal arbors in the uncrossed projection. This was accompanied by the failure of crossed fibers to form complex arbors. It is possible that a similar mechanism also operates in the formation of topographic maps.

Aging↗