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Biomedical subjects

H Sakata

Publications and source records attributed to H Sakata.

At least 37 records · Page 2Linked to original sources
PubMed2001

Thallium-201 single photon emission computed tomography (SPECT) in patients with duchenne's progressive muscular dystrophy: a histopathologic correlation study.

The pathomorphologic mechanism responsible for abnormal perfusion imaging during thallium-201 myocardial single photon emission computed tomography (201Tl-SPECT) in patients with Duchenne's progressive muscular dystrophy (DMD) was investigated. Hearts from 7 patients with DMD were evaluated histopathologically at autopsy and the results correlated with findings on initial and delayed resting 201Tl-SPECT images. The location of segments with perfusion defects correlated with the histopathologically abnormal segments in the hearts. Both the extent and degree of myocardial fibrosis were severe, especially in the posterolateral segment of the left ventricle. Severe transmural fibrosis and severe fatty infiltration were common in segments with perfusion defects. In areas of redistribution, the degree of fibrosis appeared to be greater than in areas of normal perfusion; and intermuscular edema was prominent. Thus, the degree and extent of perfusion defects detected by 201Tl-SPECT were compatible with the histopathology. The presence of the redistribution phenomenon may indicate ongoing fibrosis. Initial and delayed resting 201Tl-SPECT images can predict the site and progress of myocardial degeneration in patients with DMD.

Adolescent↗
PubMed2001

[Congenital rubella syndrome developing after a 1987-1988 epidemic in Japan].

Since vaccination legislation was revised in 1994, rubella vaccination has been changed from application to all junior high school girls with no history of clinical rubella to application to individual infants and junior high school students. This may decrease the vaccination acceptance rate and increase the chance of pregnant women's infection with rubella causing congenital rubella syndrome (CRS). We studied 5 children with CRS developed after a 1987-1988 epidemic in Japan to determine how their mothers were infected, and reviewed auditory findings. They were CRS-confirmed or CRS-compatible cases who met CRS diagnostic criteria formulated by the U.S. Center for Disease Control (CDC) in 1983. Two mothers had not been vaccinated because this was not legislated when they were in junior high school. Three were eligible for vaccination at 14, but 2 were not vaccinated. The children were born in 1991-1997. Complications were low birth weight in 3, delay in neck stabilization in 2, and cataract in 1. No case was serious. Ages at first ENT examination ranged from 3 months to 1 year and 8 months. ABR showed hearing loss of > or = 90 dBnHL. They started using hearing aids at 6 months to 1 year and 10 months. Tsumori mental development tests showed delays in developmental age in 2 who started auditory training after ages of 1 year and 6 months. Findings indicated that infants, students, and potentially pregnant women should be vaccinated. Complete serologic testing are important in pregnant women and fetal rubella infection should be diagnosed early by PCR.

Adult↗
PubMed2001

[Roles of posterior parietal cortex in stereopsis: characteristics of responses of axis-orientation-selective neurons in monkey caudal intraparietal area].

Patients with parietal lesions may fail to adjust the orientation of their hand to that of a target object, or may make errors in judging the orientation of a bar. This suggests that the parietal cortex has a function in the discrimination of the orientation of objects. In this study we investigated the responses of axis-orientation-selective neurons in caudal intraparietal (CIP) area to stereoscopic stimuli. Among the characteristics we investigated responses to the length and thickness of objects, sensitivity to binocular disparity, and position invariance in depth. Computer generated stereoscopic stimuli were presented to the monkey on a 70 inch screen. Most of the neurons responded better to long or narrow stimuli. All neurons which were orientation selective only in the frontal plane were not disparity sensitive. Most of the neurons which were orientation selective in the sagittal or horizontal plane were sensitive for binocular disparity. The majority of these neurons had wide receptive fields and their responses were position-invariant. These results suggest that the axis-orientation-selective neurons in CIP area encode the orientation of the longitudinal axis of objects in 3-dimensional space.

Animals↗
PubMed2001

Special features of old age vertigo.

In daily clinical practice, it is seen that elderly patients complain most frequently of dizziness, tinnitus, and hearing loss. Listening to those complaints, do we not tend just to attribute them to age? Against this background, we review vertigo in elderly patients briefly and consider the key points of its treatment. In comparison to younger people, what is first noticeable about elderly people is that they have a lot of fat in the body and a markedly low level of intracellular water. In other words, elderly people are always at risk of dehydration and liable to enter a shock state. The dorsal root in the elderly is also degenerated, and this explains such diverse complaints as dizziness, tinnitus, ringing in the head, headache, neck and shoulder stiffness, and lumbago. However, these complaints cannot be dismissed simply as "an unidentified syndrome." Behind these complaints is invariably one or another organic disorder. This is the conclusion we have reached from our day-to-day clinical practice.

Aged↗
PubMed2001

Treatment of cochlear tinnitus with transtympanic infusion of 4% lidocaine into the tympanic cavity.

Tinnitus is an otological symptom that is encountered often, yet its treatment is difficult. If tinnitus is of cochlear origin, a reasonable assumption is that a total depression of the cochlear function will abolish cochlear tinnitus. To achieve this depression, transtympanic infusion of a local anesthetic (4% lidocaine) to anesthetize the inner ear was conducted in a patient suffering from tinnitus. Transtympanic infusion of 4% lidocaine was performed as a treatment for cochlear tinnitus, and its efficacy was investigated. The overall efficacy rate for the 292 patients with 369 affected ears was 81%. In the investigation of the treatment results in cases of different underlying ear diseases, the efficacy rate was high for tinnitus accompanying sudden deafness and labyrinthine vertigo. However, vestibular symptoms, such as vertigo and nausea, developed after lidocaine infusion. No permanent side effects were noted. Lidocaine infusion is thought to be a useful treatment option for tinnitus and should be considered before surgical treatment. Inner ear anesthesia into the tympanic cavity has been carried out in patients who had cochlear tinnitus and in whom conservative methods of therapy, such as oral medication, had proved unsuccessful. This treatment method is useful as a local therapy for cochlear tinnitus.

Anesthetics, Local↗
PubMed2000

Effects of Different Types of Disparity Cues on the Response of Axis-orientation Selective Cells in the Monkey Parietal Cortex.

Purpose: To specify the cues for the discrimination of orientation in depth in axis orientation selective (AOS) neurons.Method: We analyzed the responses of AOS neurons in the monkey caudal intraparietal sulcus (cIPS) region using binocular disparity stimuli generated by stereoscopic 3 D computer graphics.Result: Most AOS neurons (20/27) were sensitive to binocular disparity and showed tuning to the orientation of a slit in the sagittal plane with orientation disparity cues. For 12 neurons we also used an array of discs or dots instead of slits to eliminate orientation disparity. Half of the neurons (6/12) responded better to the slits than to the discs or dots, suggesting that they were sensitive to orientation disparity. Five neurons (5/12) responded equally well to the discs or dots suggesting that they were more sensitive to the gradient of horizontal disparity than to the orientation disparity.Conclusion: Both orientation disparity and disparity gradient were likely to be integrated in the cIPS area to represent axis orientation of an object in space.

Journal Article↗
PubMed2000

Imaging of a vortex lattice transition in YNi2B2C by scanning tunneling spectroscopy

The vortex lattices in YNi2B2C under the magnetic fields H up to 3 T applied along both the a and the c axes have been studied by scanning tunneling spectroscopy at 4.2 K. The vortex lattice transition has been found to occur in different manners for H parallela and H parallelc; in H parallela a slightly distorted hexagonal vortex lattice has been found to transform to a nearly square one above 1.0 T with increasing H, while in H parallelc the transition occurs at a much lower field around 0.1 T. The unconventional steep increase of the quasiparticle density of states outside the vortex core has also been found well below H(c2).

Journal Article↗
PubMed2000

Neu differentiation factor/heregulin induction by hepatocyte and keratinocyte growth factors.

Hepatocyte growth-factor (HGF) is a potent, widely produced, pleiotropic mediator of mesenchymal-epithelial interaction. In a study of changes in gene expression initiated by HGF in Balb/MK keratinocytes, we observed the induction of Neu-differentiation factor (NDF) mRNA (also known as heregulin, or HRG). Further characterization of the regulation of NDF expression in Balb/MK keratinocytes revealed potent induction by keratinocyte growth factor (KGF) and epidermal growth factor (EGF), but not by HGF/NK2, an alternative HGF isoform with motogenic but not mitogenic or morphogenic activities. Sustained treatment (8 h) of Balb/MK cells with KGF stimulated secretion of mature NDF protein into the culture medium, and Balb/ MK cells treated with purified recombinant NDF protein showed increased DNA synthesis. We also found evidence of NDF induction in two models of tissue repair in mice: in full-thickness skin wounds, following locally increased KGF production, and in kidney after partial hepatectomy, following elevation of circulating HGF levels. These results reveal that mesenchymally-derived HGF and KGF can activate autocrine NDF signaling in their epithelial targets, and suggest that this mechanism contributes to the coordination of stages of wound repair, and possibly development, where these growth factors act in concert to direct epithelial proliferation, morphogenesis and differentiation.

Amino Acid Sequence↗
PubMed2000

Endoscopic injection sclerotherapy for esophageal varices prolonged survival of patients with hepatocellular carcinoma complicating liver cirrhosis.

BACKGROUND: A prospective controlled study was performed between 1982 and 1991 to evaluate the efficacy of endoscopic injection sclerotherapy (EIS) in patients with esophageal varices complicated by hepatocellular carcinoma and liver cirrhosis. METHODS: The study included 83 patients with esophageal varices, hepatocellular carcinoma, and liver cirrhosis. Forty-three patients (group 1) underwent prophylactic EIS or emergent EIS for bleeding varices. EIS was performed weekly 4 to 6 times until the varices disappeared. The remaining 40 patients (group 2) underwent conservative therapy and did not undergo EIS. Survival rates were compared between the 2 groups. RESULTS: During the 5-year observational period, all patients who did not undergo EIS died. Sixteen in group 2 (40.0%) died of gastrointestinal bleeding including ruptured esophageal varices. In contrast, patients treated with EIS survived significantly longer (p<0.001). Nine patients (20.9%) treated with EIS experienced gastrointestinal bleeding as a result of which 5 (11.6%) died. EIS prolonged survival in patients classified as Child's A or B but did not affect survival in patients with Child's C hepatic function. EIS was effective in prolonging survival in patients with hepatocellular carcinomas smaller than 5 cm. However, EIS had no effect in patients with hepatocellular carcinomas that were larger than 5 cm. EIS prolonged survival only for patients with nodular hepatocellular carcinoma and had no effect in patients with massive and diffuse hepatocellular carcinoma. Further, EIS prolonged survival only for patients who did not have portal vein thrombosis. CONCLUSION: Based on this prospective study, we concluded that EIS was effective in prolonging the survival period of a select subset of patients with hepatocellular carcinoma.

Aged↗
PubMed2000

A Rho-specific exchange factor Ect2 is induced from S to M phases in regenerating mouse liver.

The ect2 oncogene was originally identified as a transforming complementary DNA (cDNA) from mouse epithelial cells in an expression cloning approach and encodes a product related to Rho-specific exchange factors and yeast cell cycle regulators. To explore the potential role of ect2 in the cell cycle, we examined the expression of the ect2 proto-oncogene in a liver regeneration model in mice after partial (two thirds) hepatectomy. We found that the expression of the ect2 transcript and protein were markedly elevated with the onset of DNA synthesis and remained elevated during G2 and M phases. The timing of ect2 expression matched that of proliferating cell nuclear antigen (PCNA) and partially overlapped cell division cycle 2 (Cdc2) expression. In situ hybridization analysis showed that ect2 was expressed at a high level in cells undergoing mitosis in regenerating liver. Moreover, expression of a dominant negative or an oncogenic mutant of ect2 in cultured mouse hepatocytes resulted in a large increase in the number of binucleated cells. These findings showed that Ect2 is expressed in a cell cycle-dependent manner during liver regeneration, and suggest that it has an important role in the regulation of cytokinesis.

Animals↗
PubMed2000

[A study of bacterial meningitis in Hokkaido between 1994 and 1998].

We evaluated 82 children with bacterial meningitis in 78 institutions in Hokkaido, Japan between 1994 and 1998. The mean number of cases per year was 16.4 (range, 9 to 30). A male predominance occurred with 52 males and 30 females (1.7:1). Median age was 11 months with a range from 1 day to 11 years. Seventy-eight (95%) of the total were less than 5 years old with 55 (67%) less than 2 years old and 45 (55%) less than 1-year old. Four deaths occurred, giving an overall case fatality rate of 4.9%. Sequelae were seen at discharge in 29%, predominantly sensorineural hearing loss, epilepsy and development delay of varying severity. The main causative organisms were Haemophilus influenzae in 49 patients, Streptococcus pneumoniae in 14, Streptococcus agalactiae in 10 and Escherichia coli in 5. The frequency of poor prognosis was 50% for patients with meningitis due to S. pneumoniae or S. agalactiae compared with 27% for patients with meningitis due to H. influenzae.

Child, Preschool↗
PubMed2000

Selectivity for the shape, size, and orientation of objects for grasping in neurons of monkey parietal area AIP.

In this study, we mainly investigated the visual selectivity of hand-manipulation-related neurons in the anterior intraparietal area (area AIP) while the animal was grasping or fixating on three-dimensional (3D) objects of different geometric shapes, sizes, and orientations. We studied the activity of 132 task-related neurons during the hand-manipulation tasks in the light and in the dark, as well as during object fixation. Seventy-seven percent (101/132) of the hand-manipulation-related neurons were visually responsive, showing either lesser activity during manipulation in the dark than during that in the light (visual-motor neurons) or no activation in the dark (visual-dominant neurons). Of these visually responsive neurons, more than half (n = 66) responded during the object-fixation task (object-type). Among these, 55 were tested for their shape selectivity during the object-fixation task, and many (n = 25) were highly selective, preferring one particular shape of the six different shapes presented (ring, cube, cylinder, cone, sphere, and square plate). For 28 moderately selective object-type neurons, we performed multidimensional scaling (MDS) to examine how the neurons encode the similarity of objects. The results suggest that some moderately selective neurons responded preferentially to common geometric features shared by similar objects (flat, round, elongated, etc.). Moderately selective nonobject-type visually responsive neurons, which did not respond during object fixation, were found by MDS to be more closely related to the handgrip than to the object shape. We found a similar selectivity for handgrip in motor-dominant neurons that did not show any visual response. With regard to the size of the objects, 16 of 26 object-type neurons tested were selective for both size and shape, whereas 9 object-type neurons were selective for shape but not for size. Seven of 12 nonobject-type and all (8/8) of the motor-dominant neurons examined were selective for size, and almost all of them were also selective for objects. Many hand-manipulation-related neurons that preferred the plate and/or ring were selective for the orientation of the objects (17/20). These results suggest that the visual responses of object-type neurons represent the shape, size, and/or orientation of 3D objects, whereas those of the nonobject-type neurons probably represent the shape of the handgrip, grip size, or hand-orientation. The activity of motor-dominant neurons was also, in part, likely to represent these parameters of hand movement. This suggests that the dorsal visual pathway is concerned with the aspect of form, orientation, and/or size perception that is relevant for the visual control of movements.

Animals↗
PubMed2000

Parietal neurons represent surface orientation from the gradient of binocular disparity.

In order to elucidate the neural mechanisms involved in the perception of the three-dimensional (3D) orientation of a surface, we trained monkeys to discriminate the 3D orientation of a surface from binocular disparity cues using a Go/No-go type delayed-matching-to-sample (DMTS) task and examined the properties of the surface-orientation-selective (SOS) neurons. We recorded 57 SOS neurons from the caudal part of the lateral bank of the intraparietal sulcus (area CIP) of three hemispheres of two Japanese monkeys (Macaca fuscata). We tested 29 of 57 SOS neurons using the square plate of a solid figure stereogram (SFS) and random-dot stereogram (RDS) without perspective cues; almost all of the tested neurons (28/29) showed surface orientation selectivity for the SFS and/or the RDS without perspective cues. Eight of these 28 neurons (28.6%) showed selectivity for both the RDS and SFS, 7 (25.0%) were dominantly selective for the RDS, and 13 (46.4%) were dominantly selective for the SFS. These results suggest that neurons that show surface orientation tuning for the RDS without perspective cues compute surface orientation from the gradient of the binocular disparity given by the random-dot across the surface. On the other hand, neurons that show surface orientation tuning for the SFS without perspective cues may represent surface orientation primarily from the gradient of the binocular disparity along the contours. In conclusion, the SOS neurons in the area CIP are likely to operate higher order processing of disparity signals for surface perception by integrating the input signals from many disparity-sensitive neurons with different disparity tuning.

Animals↗
PubMed2000

[Effects of different types of disparity cues on the response of axis-orientation selective cells in the monkey parietal cortex].

PURPOSE: To specify the cues for the discrimination of orientation in depth in axis orientation selective (AOS) neurons. METHODS: We analyzed the responses of AOS neurons in the monkey caudal intraparietal sulcus (cIPS) region using binocular disparity stimuli generated by stereoscopic 3 D computer graphics. RESULTS: Most AOS neurons (20/27) were sensitive to binocular disparity and showed tuning to the orientation of a slit in the sagittal plane with orientation disparity cues. For 12 neurons we also used an array of discs or dots instead of slits to eliminate orientation disparity. Half of the neurons (6/12) responded better to the slits than to the discs or dots, suggesting that they were sensitive to orientation disparity. Five neurons (5/12) responded equally well to the discs or dots suggesting that they were more sensitive to the gradient of horizontal disparity than to the orientation disparity. CONCLUSION: Both orientation disparity and disparity gradient were likely to be integrated in the cIPS area to represent axis orientation of an object in space.

Animals↗
PubMed2000

Cephalometric comparisons of craniofacial and upper airway structures in young children with obstructive sleep apnea syndrome.

We studied 15 children of preschool age who had obstructive sleep apnea syndrome to evaluate their dentofacial morphology in relation to the pharyngeal airway space. We found that (1) sleep apnea was often associated with mandibular retrognathia, (2) the lower incisors tended to exhibit a retrocline, (3) there were no significant differences in angular and linear measurements in the cranial base between patients with sleep apnea and a control group of 30 nonapneic children, and (4) the apneic children had a narrower epipharyngeal airway space than did the controls. These findings suggest that obstructive sleep apnea is probably caused by both adenoidal hypertrophy and abnormal development of the facial skeleton. We highly recommend cephalometric analysis as a valuable tool for conducting the presurgical evaluation of sleep apnea in children of preschool age.

Adenoids↗
PubMed2000

Reoperation for graft failure of femoropopliteal bypass with externally supported knitted Dacron prosthesis.

BACKGROUND: Aggressive reoperation for failing or failed femoropopliteal (FP) bypass has been affirmative despite graft material. There has been no report regarding results of reoperation for FP bypass with externally supported knitted Dacron prosthesis (EXS). The aim of this study is to justify aggressive reoperation of FP bypass with EXS and to examine risk factors affecting the result of reoperation. METHODS: A retrospective review was performed on 204 patients undergoing 212 FP bypasses (with EXS between January 1982 and December 1997 and 34 FP EXSes of 32 patients underwent reoperation for graft failure until March 1998. The cumulative graft patency (GP) and limb salvage (LS) rate after first reoperation for 34 FP bypass EXS were calculated and the importance of each perioperative factor on GP or LS was estimated by uni- and multivariate analysis. RESULTS: Reoperated 34 FP EXSes included 12 failing and 22 failed grafts and 14 limbs with failed grafts underwent reoperation for limb salvage. The GP of 34 grafts and LS of 14 limbs rate were 58 and 67% at 2 years, respectively. Univariate analysis identified graft thrombosis (2 years GP; failing graft: failed graft=78: 48%) and continuance of smoking (2 years LS; smoker: non-smoker=43: 100%) as a significant risk factor of GP and IS, respectively, neither of which was significant by multivariate analysis. CONCLUSIONS: Early diagnosis and treatment, before graft thrombosis, can lead to superior durability of GP and discontinuance of smoking is important for LS.

Aged↗
PubMed2000

Critical limb ischemia in a patient with von Recklinghausen's neurofibromatosis. Report of a case.

A 42-year-old woman complicated with neurofibromatosis underwent both balloon percutaneous transluminal angioplasty (PTA) of the iliac artery and femoropopliteal (FP) bypass grafting for critical lower limb ischemia. Seven months after the initial intervention, a recurrence of stenosis in the iliac artery and at the anastomoses of the FP bypass necessitated both PTA and a repeat thrombectomy and finally resulted in the amputation of her left thigh. This is a rarely documented case of chronic arterial occlusion associated with neurofibromatosis, in which the prognosis of arterial reconstruction for such patients is suggested to be poor.

Adult↗