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T Sakai

Publications and source records attributed to T Sakai.

At least 451 records · Page 25Linked to original sources
PubMed1998

Characteristic magnetic resonance imaging findings in Machado-Joseph disease.

OBJECTIVE: To clarify the characteristic magnetic resonance imaging (MRI) findings in patients with Machado-Joseph disease (MJD) diagnosed by genetic analysis. PATIENTS AND METHODS: Using MRI, we examined 31 patients genetically diagnosed as having MJD, 20 patients with sporadic olivopontocerebellar atrophy, and 26 control subjects. RESULTS: The MRIs of patients with MJD disclosed remarkably reduced width of the superior cerebellar peduncles, atrophy in the frontal and temporal lobes, diminished transverse diameter of the globus pallidus, and decreased anteroposterior and transverse diameters of the pons, which correlated with the width of the middle cerebellar peduncle. The width of the superior cerebellar peduncles also correlated with the diameter of the dentate or red nucleus in patients with MJD, but not in controls or in patients with sporadic olivopontocerebellar atrophy. On T2- and/or proton-weighted axial MR imaging, a high signal intensity in the transverse pontine fibers was observed in 14 (45.2%) of 31 patients with MJD and in all patients with sporadic olivopontocerebellar atrophy, but not in any controls. CONCLUSION: Affected afferent and efferent cerebellar tracts and atrophy of the frontal and temporal lobes and globus pallidus are characteristics of MRI of patients with MJD.

Adult↗
PubMed1998

Computed-tomography-based computer preoperative planning for total hip arthroplasty.

For precise preoperative planning in total hip arthroplasty (THA), we developed a technique of computed tomography (CT)-based computer preoperative planning and compared this technique with the single X-ray and template method generally used. The subjects of this study were 42 hips in 38 patients who underwent THA using a cementless total hip system. Preoperatively, a standard anteroposterior X-ray of the hip was taken, and conventional preoperative planning was done with a template of the total hip system. Transverse images were obtained using a helical CT scanner, and a CT-based computer preoperative plan was performed on true coronal slice images of the proximal femur reconstructed from CT data. Postoperatively, 29 hips (69%) showed good proximal fit of the femoral component to the medial endosteal line. Of the 20 hips with good proximal fit on preoperative X-ray planning, 12 hips had good proximal fit on postoperative X rays. Sensitivity and specificity of the proximal fit on X-ray templating were 41 and 23%, respectively. In 27 of 28 hips with good proximal fit on reconstructed CT images preoperatively, the postoperative X ray revealed good proximal fit. Sensitivity and specificity of the proximal fit on computer planning were 93 and 86%, respectively. Twelve hips with good proximal fit on preoperative templating, the reconstructed images, and the postoperative X ray had 20 degrees or less of combined femoral neck anteversion and external rotational contracture of the hip on the X-ray table. Eight hips with good proximal fit on preoperative templating and proximal poor fit on the reconstructed images had 17-65 degrees of combined version and rotational contracture. In 16 hips with poor proximal fit on preoperative templating and good proximal fit on the reconstructed images, the combined version and rotational contracture ranged from 17 to 69 degrees. When combined femoral neck anteversion and external rotational contracture of the hip is less than 15 degrees, the simple X-ray and template method might be sufficient for THA planning. Otherwise, the CT-based method of preoperative planning is recommended.

Arthroplasty, Replacement, Hip↗
PubMed1998

The vascular pole of the renal glomerulus of rat.

In the present study we provide a detailed structural analysis of the vascular pole of superficial and midcortical glomeruli of the rat kidney. A description of the juxtaglomerular portions of the afferent and efferent arterioles, the extraglomerular mesangium and the glomerular stalk is included. The specific structural elaboration of the epithelial transition from the podocytes to the parietal epithelium is emphasized, with particular attention to the arrangement of the cytoskeleton and its connections to extracellular matrix elements. The branching patterns of the afferent and efferent arterioles are quite different. Immediately at the glomerular entrance, the afferent arteriole divides into its primary branches. In contrast, the efferent arteriole has a specific outflow segment (consisting of an intraglomerular portion and a portion associated with the extraglomerular mesangium) established by the confluence of capillary tributaries deep inside the glomerular tuft. Just at the transition from inside to outside, this segment includes a prominent narrow portion with conspicuous endothelial cells bulging into the vessel lumen. The extraglomerular mesangium has been found to represent a solid block of cells and matrix filling the space between the macula densa and both arterioles and extending into the entrance funnel. Peripherally located extraglomerular mesangial cells attach to the outer aspect of the parietal basement membrane. As a whole, the extraglomerular mesangium occludes the glomerular tuft. The results appear relevant with respect to four major aspects: (1) a support function counteracting the expansile forces resulting from the high intraglomerular pressures, (2) a direct functional influence of the afferent on the efferent arteriole, resulting from their narrow assemblage at the glomerular entrance, (3) a specific shear stress receptor function of the intraglomerular segment of the efferent arteriole, and (4) fluid leakage from the glomerular tuft through the stalk and the extraglomerular mesangium into the cortical interstitium. 1. The glomerulus is a high-pressure compartment; expansile forces continuously tend to expand glomerular capillaries, the glomerular stalk, and the glomerular entrance. Counteracting centripetal forces at the vascular pole appear to be developed as circular forces by the cytoskeleton of podocytes and parietal cells surrounding the glomerular entrance and as interconnecting forces between both arterioles and between opposing walls of the glomerular entrance, as well as of the glomerular stalk. These interconnecting forces are developed by the extraglomerular mesangium which--as a whole--forms a spiderlike closure device holding the glomerular entrance together. In addition, the extraglomerular mesangium develops occluding forces, allowing a gradual pressure drop between the glomerular stalk and the macula densa. 2. At the glomerular entrance, the outflow segment of the efferent arteriole is narrowly associated with the bifurcation of the afferent arteriole. Both are enclosed together in a common compartment surrounded by the glomerular basement membrane; there is no pressure barrier individually encompassing each vessel. Therefore, it may readily be suggested that the hydrostatic pressure of the afferent arteriole acts on the efferent arteriole. As a consequence, the luminal width of the efferent arteriole at this site, i.e., its resistance, may be directly modified by the pressure in the afferent arteriole. 3. The efferent arteriole at the transition of the intraglomerular segment to the segment that passes through the extraglomerular mesangium has a conspicuously narrow portion with endothelial cells protruding into the vessel lumen. In addition, this segment is prominent by the expression of the neuronal type of nitric oxide synthase. We therefore propose that this segment acts as a specific shear stress receptor. The possible relevance of a shear stress receptor at this site would be

Animals↗
PubMed1998

Multifocal clear cell meningioma in the spine: a case report.

Clear cell meningioma is a rare morphologic form of meningioma. This case report describes a very rare case of multifocal clear cell meningioma in the thoracic and lumbar spine. A 9 year old patient presented with back pain and popliteal pain, which were aggravated by trunk motion and knocking. Magnetic resonance imaging (MRI) suggested a meningioma at the L2 level. An intradural extramedural tumor attached to the cauda equina was surgically removed and pathological diagnosis was clear cell meningioma. The patient began to complain of back pain at the Th12 level 4 months postoperatively. Retrospective analysis of MRI before the first operation revealed the small tumors at Th12 and L5 levels; comparison with a new MRI showed the rapid growth in 4 months. Adjunctive surgical resection was carried out and the back pain disappeared. These tumors had the same pathological findings. In conclusion, in young patients with suggested meningioma in the lumar spine, clear cell meningioma should also be considered, and the possibility of multifocal occurrence and postoperative recurrence must be taken into account.

Age of Onset↗
PubMed1998

Haemodynamic and electroencephalograph responses to intubation during induction with propofol or propofol/fentanyl.

PURPOSE: To observe the changes in EEG bispectral index (BIS), 95% spectral edge frequency (95% SEF) and median frequency (MF) with haemodynamic changes to intubation during induction with propofol or propofol and 2 micrograms.kg-1 fentanyl i.v. METHODS: Twenty four ASA I-II patients were randomized to receive either propofol infusion preceded by normal saline (group P, n = 12) or propofol preceded by 2 micrograms.kg-1 fentanyl (group PF, n = 12). Intubation was performed five minutes after maintenance of BIS within 45 +/- 5. EEG and haemodynamic variables were recorded at before induction, and before and after intubation. RESULTS: Haemodynamic responses to intubation were greater in group P than in group PF (P < 0.05). Postintubation SBP, DBP and HR increased, compared with preinduction values, more in group P than in group PF. Postintubation BIS values increased from 45.5 +/- 3.5 and 44.2 +/- 4.1 to 51.1 +/- 4.1 and 50.9 +/- 5.3 in groups P and PF, respectively, compared with preintubation values. The BIS values were not different between treatment groups before and after intubation, and 95% SEF and MF values did not increase after intubation. CONCLUSION: Fentanyl, 2 micrograms.kg-1 i.v., blunted the haemodynamic responses to intubation, but failed to attenuate the arousal of cerebral cortical activity. The different haemodynamic responses postintubation but similar BIS and 95% SEF changes in the two groups suggest that BIS or 95% SEF cannot predict the haemodynamic responses to intubation during anaesthesia induction with propofol and fentanyl.

Adolescent↗
PubMed1998

A regional gradient of cardiac intrinsic rhythmicity depicted in embryonic cultured multiple hearts.

We used optical methods to examine the spatial gradient of intrinsic rhythmicity in early-stage multiple-heart chick embryos. The latter were induced experimentally in whole-embryo culture. The embryos were cut microsurgically through the tissue of the anterior intestinal portal at the 5- to early 7-somite developmental stage. Spontaneous electrical activity in 4 to 6 segmented hearts, during the 7- to 10-somite stages of development, were monitored simultaneously by means of multiple-site optical recordings of membrane potential activity, using a voltage-sensitive merocyanine-rhodanine dye (NK2761). Each segment of the heart exhibited its own inherent rhythmicity. In quadruple hearts, the order of the rhythmicity was often left-caudal segment>right-caudal segment>left-cephalic segment>right-cephalic segment; the heart rate in the left-caudal segment was often faster than that in the other segments. An atypical pattern of "bursting" rhythm was observed in the cephalic segments suggesting that, in these segments, the development of rhythmicity is relatively poor. These findings strongly emphasize the concept that, in the early phases of cardiogenesis, the formation of a regional gradient of pacemaker activity (i.e. a spatial gradient of intrinsic rhythmicity) results in the functional self-organization of the pacemaking area.

Action Potentials↗
PubMed1998

Angiotensin II maintains the structure and function of glomerular mesangium via type 1a receptor. What we have learned from null mutant mice minus the angiotensin II type 1a receptor gene.

The angiotensin II type 1a (AT1a) receptor is the major receptor effecting the multiple actions of angiotensin II on the cardiovascular system. It is expressed abundantly in the glomerular mesangial cells of the kidney. We investigated glomerular changes in null mutant mice minus the AT1a receptor gene to gain an understanding of the in vivo action of angiotensin II via AT1a on the mesangium. Morphological observations and morphometric analysis revealed that the glomerular volume was greatly increased owing to the expansion of the mesangial area, which contained fluid-filled spaces with a small amount of fibrillar components. The mesangial cells lost contact with each other and with the perimesangial area of the glomerular basement membrane (GBM), so that the glomerular capillary neck was greatly widened. These findings suggest a defect of the anchoring function of mesangial cells resulting from some abnormality in mesangial matrix formation. We conclude that angiotensin II has an important role in the structural and functional maintenance of the mesangium via the AT1a receptor, especially by reinforcing the connection between mesangial cells and GBM via the mesangial matrix.

Angiotensin II↗
PubMed1998

Clinical use of a front lifting hood rectoscope tube for transanal endoscopic microsurgery.

BACKGROUND: Transanal endoscopic microsurgery (TEM), a procedure developed by Buess et al. requires a specially designed surgical rectoscope system, and adequate training for its operation is mandatory. In order to simplify the performance of TEM, and to allow the use of additional surgical instruments and devices, we have developed a new rectoscope tube. METHODS: The forward half of the tube can be opened longitudinally by hand. Our working insert platform is hollowed and includes a channel for an endoscope. The resection procedure can be performed under normal atmospheric pressure. This newly developed rectoscope system has already been employed clinically. TEM was performed using our original forward lifting hood rectoscope tube in 20 patients, including 12 cases of sessile adenoma and eight cases of early carcinoma. RESULTS: The forward hood of the tube was opened to the maximum angle of 25 degrees in eight patients and 15-20 degrees in the other 12 patients. The visible field of the rectal interior was extended in direct proportion to the angle. Through our working insert platform, instruments and devices could be used for either laparoscopic or open surgery. CONCLUSIONS: These modifications have made TEM easier and will therefore make the procedure available to more surgeons.

Aged↗
PubMed1998

Thoracoscopic transdiaphragmatic microwave coagulation therapy for a liver tumor.

BACKGROUND: Microwave coagulation therapy (MCT) for hepatocellular carcinoma, which induces tumor coagulonecrosis, is now recognized as an efficient treatment. However, when a tumor is located just below the top of the diaphragmatic dome, laparotomical MCT requires a large incision, and percutaneous MCT is sometimes impossible. PATIENTS AND METHODS: The patients were four men and two women. There were four cases of hepatocellular carcinoma and two cases of liver metastasis from colorectal cancer. All tumors were located below the top of the diaphragmatic dome. Thoracoscopic transdiaphragmatic MCT (TTMCT) was performed under general anesthesia using an endotracheal double-lumen tube. Identification of the tumor site in the liver was performed using an ultrasonic probe under thoracoscopic observation. After the diaphragm above the tumor was opened, a needle electrode to transmit microwaves was inserted directly into the tumor. Microwave irradiation was repeated to coagulate the entire lesion. After completion of TTMCT, the diaphragm was closed thoracoscopically. RESULTS: TTMCT was successfully administered to cancerous lesions in all six patients. The postoperative course was uneventful, and the average postoperative hospitalization period was 10.5 days. None of the patients has shown any recurrence during a follow-up period of 4-23 months. CONCLUSIONS: TTMCT was performed without any difficulty using the thoracoscopic surgical technique, and its therapeutic outcome was satisfactory. This is effective for tumors located just below the top of the diaphragmatic dome.

Aged↗
PubMed1998

Spontaneous intracranial hypotension associated with subdural hematoma: diagnostic usefulness of percutaneous subdural tapping and magnetic resonance imaging.

A 55-year-old woman presented with headache which was characterized by aggravation in the upright position and relief in recumbency. Although intracranial hypotension syndrome was considered to be the most-likely possible entity, computed tomography (CT) scans demonstrated subdural fluid collections associated with findings reminiscent of transtentorial herniation. Because of these CT features, cerebrospinal fluid pressure measurement by a lumbar puncture was not performed. In stead, as an alternative method, she underwent percutaneous subdural tapping, which failed to obtain spontaneous drainage of liquid haematoma, indicating intracranial hypotension. In addition, gadolinium-enhanced magnetic resonance imaging study performed later supported the diagnosis of spontaneous intracranial hypotension. Thus, the usefulness and safety of percutaneous subdural tapping for the diagnosis of spontaneous intracranial hypotension is stressed.

Female↗
PubMed1998

Interleukin 15 activity in the rectal mucosa of inflammatory bowel disease.

BACKGROUND & AIMS: Interleukin (IL)-15 has been found to share many immunoregulatory activities in lymphocytes with IL-2. The aim of this study was to investigate IL-15 activity in organ cultures, localization of IL-15 messenger RNA (mRNA), and proliferation of lamina propria mononuclear cells (LPMCs) in response to recombinant IL-15 using the mucosal tissues obtained from patients with inflammatory bowel disease (IBD). METHODS: The contents of IL-15, tumor necrosis factor alpha, and IL-2 in the culture supernatant of the rectal mucosal tissues were determined by an enzyme-linked immunosorbent assay. Expression of IL-15 mRNA was analyzed by in situ hybridization, and proliferative response of LPMCs to recombinant IL-15 was determined by [3H]thymidine incorporation into DNA. RESULTS: Significantly greater IL-15 activity was detected in active IBD, and this elevation was also observed in inactive ulcerative colitis. In contrast, greater tumor necrosis factor alpha activity was observed only in active IBD, and IL-2 was not detected in organ cultures. In situ hybridization showed IL-15 mRNA in macrophages and epithelial cells in active IBD specimens, and recombinant IL-15 induced a dose-dependent proliferative response in LPMCs. CONCLUSIONS: Mucosal IL-15 may be involved in the pathogenesis of IBD as one of the important mediators in activation of mucosal immune cells.

Adolescent↗
PubMed1998

Neuropathological study of gazelle herpesvirus 1 (equine herpesvirus 9) infection in Thomson's gazelles (Gazella thomsoni).

Gazelle herpesvirus (GHV-1), correctly designated as equine herpesvirus 9, is a new type of equine herpesvirus immunologically related to equine herpesvirus 1 (EHV-1). As a sequel to a virological study, the neuropathology of encephalitis caused by GHV-1 in Thomson's gazelles (Gazella thomsoni) was examined. Seven gazelles died with or without neurological symptoms between early September and mid-October in 1993. No gross abnormalities were observed at necropsy, but all animals had non-suppurative encephalitis, characterized by necrosis and degeneration of neurons, glial reactions and perivascular cuffing in the cerebrum. Five cases showed intranuclear inclusion bodies, with the appearance of herpesvirus in the degenerating neurons. Immunohistochemically, all seven animals showed a positive reaction to EHV-1 antigen in neurons in the necrotic areas of the cortex. The clinical course and morphological features of GHV-1 encephalitis were distinct from those of EHV-1-induced encephalitis in the horse, which is characterized by vasculitis, thrombosis, ischaemia, and lack of intranuclear inclusions in neurons.

Animals↗
PubMed1998

The "first generation" of endovascular stent-grafts for patients with aneurysms of the descending thoracic aorta.

OBJECTIVE: Our goal was to determine whether endovascular stent-grafting is feasible and effective for patients with aneurysms of the descending thoracic aorta. METHODS: Starting in July 1992, we conducted a prospective, uncontrolled clinical trial in 103 patients (mean age 69 years [range 34-89 years]) who underwent endovascular treatment of aneurysms of the descending thoracic aorta using a custom-fabricated, self-expanding stent-graft device. Follow-up was 100% complete and averaged 22 months. Sixty-two patients (60%) were judged not to be reasonable candidates for a conventional "open" surgical procedure. RESULTS: Complete thrombosis of the aneurysm was ultimately achieved in 86 (83%) patients. The early mortality rate was 9% +/- 3% (+/- 70% CL). Multivariable analysis revealed that myocardial infarction or stroke was linked with a higher likelihood of early death (P = .001). Early serious complications included paraplegia in 3% +/- 2% and stroke in 7% +/- 3%. Actuarial survival estimates at 1 year and 2 years were 81% +/- 4% and 73% +/- 5% (+/- 1 SE), respectively; being judged not to be a surgical candidate portended a higher probability of death (P = .003). According to the intent-to-treat principle, "treatment failure" (including all late sudden unexplained deaths) occurred in 38 patients; 53% +/- 10% of patients were free from treatment failure at 3.7 years. Stent-graft related complications occurred commonly and were linked with several anatomic, technical, and patient-related risk factors. CONCLUSIONS: This 5-year clinical trial involving use of a "first generation" device indicates that endovascular stent-grafting of descending thoracic aortic aneurysms is feasible with acceptable medium-term results. More refined, commercially developed devices available today offer less traumatic and more precise stent-graft deployment; these major technical advantages, coupled with important lessons we have learned over time and better patient selection, should be associated with more salutary clinical results in the future.

Adult↗
PubMed1998

Noninvasive hemodynamic measurements of superior mesenteric artery in the prediction of portal pressure response to propranolol.

BACKGROUND/AIMS: The portal pressure response to propranolol administration is heterogeneous in patients with cirrhosis. The aim of this study was to examine the diagnostic accuracy of noninvasive hemodynamic parameters of superior mesenteric artery (SMA) and femoral artery (FA) in the prediction of portal pressure response to propranolol. METHODS: Twenty-six patients with cirrhosis were studied. Portal pressure was assessed by measurements of hepatic venous pressure gradient. Mean arterial pressure and heart rate were also recorded. Cardiac index, and flow velocity of SMA and FA, and pulsatility index of SMA and FA were then measured by means of Doppler ultrasonography. After intravenous propranolol administration (0.10 mg/kg), the above measurements were repeated. RESULTS: Propranolol significantly reduced cardiac index, heart rate, SMA flow velocity, and FA flow velocity and increased SMA pulsatility index and FA pulsatility index. Although propranolol significantly decreased hepatic venous pressure gradient, a reduction of > or =20% was seen in only 10 patients (good responders); the remaining 16 patients exhibited <20% reduction (poor responders). No significant differences in clinical and baseline hemodynamic data were found in the two groups. There were no also significant differences in changes in heart rate and cardiac index. However, reductions in SMA and FA flow velocity were significantly greater in good responders than in poor responders. Although there was no the increase in FA pulsatility index, the increase in SMA pulsatility index was significantly greater in good responders than in poor responders. When appropriate cut-off points were determined for these variables, overall predictive values of SMA flow velocity (-20%) and SMA pulsatility index (+15%) were 91% and 83%, whereas the overall predictive value of FA flow velocity (-25%) was only 69%. CONCLUSIONS: These results suggest that SMA flow velocity and SMA pulsatility index, but not FA flow velocity and FA pulsatility index, are useful noninvasive parameters in the prediction of portal pressure response to propranolol administration.

Adult↗
PubMed1998

Upright posture decreases esophageal varices flow velocity in patients with cirrhosis.

BACKGROUND/AIMS: Patients with cirrhosis tend to have esophageal variceal bleeding episodes at night, rather than during the day time. Since human beings carry on ordinary activities in the upright posture in the day time and are recumbent at night, we hypothesized that posture may be a factor related to a circadian variation of variceal bleeding. The aim of this study was to examine the effect of upright posture on esophageal varices hemodynamics in patients with cirrhosis. METHODS: Nine patients with cirrhosis and esophageal varices were included in a crossover study performed on 2 separate days. On the non-endoscopic day, cardiac output, portal vein flow velocity, and superior mesenteric artery flow velocity were measured with percutaneous Doppler ultrasonography. Plasma renin activity and plasma norepinephrine concentrations were also determined. On the endoscopic day, in addition to the above measurements, esophageal varices flow velocity was measured using transesophageal Doppler ultrasonography. These measurements were performed in the supine position and 20 min after the assumption of the upright position. RESULTS: On the non-endoscopic day, the upright posture significantly decreased cardiac output, portal vein flow velocity, and superior mesenteric artery flow velocity. Plasma renin activity and plasma norepinephrine concentration were significantly increased after assumption of the upright position. On the endoscopic day, similar hemodynamic and hormonal changes were observed. In addition, the upright posture significantly decreased esophageal varices flow velocity. Furthermore, the magnitude of the reduction in esophageal varices flow velocity (-42%) was significantly greater than that in portal vein flow velocity (-22%, p<0.01) and that in superior mesenteric artery flow velocity (-25%, p<0.01). Although the change in esophageal varices flow velocity was not significantly correlated with that in plasma renin activity (r=-0.28) and that in plasma norepinephrine concentration (r=-0.10), it was significantly correlated with the change in superior mesenteric artery flow velocity (r=0.73, p<0.05). CONCLUSIONS: The upright posture decreases esophageal varices flow velocity mainly because of the reduction in splanchnic blood flow. This effect may contribute to a low prevalence of esophageal variceal bleeding in the day time in patients with cirrhosis.

Aged↗