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Biomedical subjects

Y Sakamoto

Publications and source records attributed to Y Sakamoto.

At least 973 records · Page 54Linked to original sources
PubMedDate not supplied

Susceptibility of severe combined immunodeficient (SCID) mice to Mycobacterium leprae: multiplication of the bacillus and dissemination of the infection at early stage.

Inoculation of M. leprae were made into the both hind feet at a dose of 4.8 x 10(6) bacilli per foot in order to determine the susceptibility to M. leprae of SCID mice which is severely deficient in both T- and B cell immunity. SCID mice was found to have an extremely high susceptibility to M. leprae, and the progress of infection observed in the SCID mice were shown a rapid systemic spread of infection at the all over the tissues as well as the growth of the leprosy bacilli at the site of inoculation. Therefore, SCID mice can be used as a suitable multibacillary model for the study of leprosy.

Animals↗
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Rupture of hepatocellular carcinoma after transcatheter arterial embolization: an unusual case.

Rupture of hepatocellular carcinoma (HCC) as a complication of transcatheter arterial embolization (TAE) is very rare. An unusual rupture of HCC after TAE was treated with successful surgical resection. A 65 year-old woman with liver cirrhosis developed multiple HCC in both lobes of the liver. TAE was attempted for the HCCs, but the original left hepatic artery, obliterated due to the previous repeated TAEs, was replaced by the left gastric artery. Right hepatic arteries were embolized while preserving the replaced left hepatic artery. Nine days after TAE, the patient presented a rupture of HCC in the left lateral segment of the liver, in which no deposit of Lipiodol was recognized. Since additional TAE to achieve hemostasis failed, left lateral segmentectomy was carried out with concern for the poor hepatic functional reserve. The patient was discharged 3 weeks after surgery without any complication. This is the first case of ruptured HCC in the non-embolized part of the liver after TAE, which was resected successfully.

Aged↗
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Pringle's maneuver lasting 322 min.

Up to now, the reported limit of 'continuous' Pringle's maneuver during hepatectomy has not exceeded 127 min. Here we used 'intermittent' clamping to increase the cumulative time of safe ischemia. A 49 year-old man who had undergone jejunal resection because of leiomyosarcoma was referred with 18 hepatic metastases. Using 'intermittent' Pringle's maneuver, enucleation of the entire tumor was performed. The cumulative ischemic time of the liver was 322 min, but post-operative serum level total bilirubin remained normal. The patient was discharged on day 24 without any complications, remaining well for up to 5 months after surgery. The present case shows that the safe upper limit of cumulative hepatic ischemia can be extended to 322 min.

Constriction↗
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Surgical management for adrenal gland metastasis of hepatocellular carcinoma.

BACKGROUND/AIMS: Although the adrenal gland is one of the common sites for metastasis from hepatocellular carcinoma, the significance of adrenalectomy for treatment of metastatic hepatocellular carcinoma still remains unclear. METHODOLOGY: Analysis of 4 patients with adrenal metastasis from among 390 patients with hepatocellular carcinoma admitted to our department between October 1994 and December 1997, and a review of 79 cases reported between 1984 and 1997, were performed. RESULTS: Four patients with adrenal metastasis, right in 2 and left in 2, underwent surgical treatment. Three of the patients developed tumor thrombi in the renal vein or inferior vena cava. Diagnosis of adrenal metastasis was made by ultrasonography or computed tomography scan, following an increase in serum tumor markers. Adrenalectomy with removal of the venous tumor thrombi was performed successfully. Three patients died of recurrence within 1 year, and one patient died due to other causes showing no recurrence at autopsy. The literature review revealed the left-sided metastases were significantly larger than the right-sided ones (p < 0.01). There was no significant difference in the survival periods between left and right metastasis, or between patients who underwent adrenalectomy and those treated by other means (p > 0.05). CONCLUSIONS: The rationality of surgical treatment for adrenal metastasis from hepatocellular carcinoma still remains controversial. However, we believe that adrenalectomy would be a safe procedure and increases the chance of survival for patients.

Adrenal Gland Neoplasms↗
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Appraisal of two-staged pancreatoduodenectomy: its technical aspects and outcome.

BACKGROUND/AIMS: Leakage from the pancreaticoenteric anastomosis after pancreatoduodenectomy is closely associated with intraabdominal hemorrhage, thus contributing to mortality. Recently, two-staged pancreatoduodenectomy including exteriorization of the pancreatic juice and second-look pancreaticojejunostomy was performed in high-risk patients. METHODOLOGY: The authors reviewed 24 patients who underwent two-staged pancreatoduodenectomy from November 1994 to April 1999. RESULTS: Oral intake could be instituted on the 6th (mean) postoperative day. In 23 of the 24 patients, the pancreatic juice leakage stopped within a mean of 10 days without any complications. In the remaining 1, the leakage lasted over 4 weeks and intraabdominal bleeding from the gastroduodenal artery occurred. The median interval between pancreatoduodenectomy and the second operation was 124 days (range: 93-323 days). In 15 patients, a stent tube was placed at the site of pancreaticojejunostomy: 1 patient developed acute pancreatitis due to dislocation of the stent tube, in 3, pancreatic juice leakage necessitated exteriorization of the juice, and the remaining 11 recovered uneventfully. In the other 9 patients, the pancreatic juice was exteriorized: 1 patient had leakage and the other 8 recovered uneventfully. Overall, there was no mortality. CONCLUSIONS: Our two-staged pancreatoduodenectomy is considered to make pancreatoduodenectomy performable safely without any mortality. This procedure is recommended for selected patients, including those who require concomitant major hepatectomy or resection of other organs or who have liver cirrhosis, and may be indicated for patients who have a soft and fragile pancreas or pancreatic trauma.

Evaluation Studies as Topic↗
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MR imaging of late radiation brain injury.

One hundred and four patients treated with radiotherapy for intracranial tumors and their related conditions were reviewed to evaluate the usefulness of magnetic resonance (MR) imaging in demonstrating increased signal intensity areas on T2-weighted images that were considered to be late adverse effects of irradiation of the brain. High signal intensity areas of the white matter were divided into five patterns according to their size and extension. Severity was found to increase with age and irradiation doses of more than 50 Gy. In patients with irradiation doses of more than 60 Gy, the severity of increased with shorter interval after radiotherapy than in those given low irradiation doses. Clinical findings such as mental deterioration, motor abnormality, and visual defect were observed in 12 patients. These findings were closely correlated with the severity of the MR pattern. In most patients, high signal intensity areas were stable or progressive during the course of follow-up. However, these areas were regressive in three patients. Imaging with Gd-DTPA was performed in 36 patients, six of whom showed enhancement. Pathological findings on enhancement included astrocyte proliferation and coalescing vacuoles in neural tissue. MR imaging is an excellent method with which to monitor the adverse effects of radiotherapy of the brain.

Adult↗
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MR Gd-DTPA enhancement of radiation brain injury.

MR examinations of 104 patients who had undergone radiotherapy to the brain were reviewed. Thirty-six patients received Gd-DTPA enhanced study during the course of MR evaluation and six of the patients showed enhancing radiation necrosis. Histopathological confirmations were obtained in three patients. Gd-DTPA enhancing radiation lesions were multiple and patchy in three patients, multiple and patchy with cyst formation in two and ring shaped in one. In terms of their distribution, enhancing lesions in four patients were seen only in the white matter within the irradiated field and these patients had undergone radiotherapy within five years. The interval after radiotherapy was more than eight years in two patients and their enhanced lesions were observed in both the white and gray matter. Histopathological findings of Gd-DTPA enhancing radiation necrosis were gliosis and coalescing vacuoles of the neural tissue. None of these enhanced radiation lesions showed significant mass effects. Patterns of the enhancement were not specific. It was considered to be difficult to differentiate tumor recurrence from radiation necrosis with conventional Gd-DTPA enhanced MR examinations. In one patient, delayed MR images after Gd-DTPA administration showed increases in the size and number of radiation enhanced lesions. Dynamic and delayed MR study might add more information to conventional imaging after Gd-DTPA. Further studies are necessary to differentiate radiation lesions from tumor recurrences.

Adult↗
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Quantitative measurement of high flow velocities by a spin echo MR technique.

A new method of flow measurement using a spin echo (SE) technique has been developed on the basis of the flow effect that at high velocities signal intensity decreases linearly with increasing flow velocity. Flow velocity is calculated from the signal intensity ratio of the flowing material in two images with the same imaging parameters but different echo times. The linear relationship between the signal intensity and flow velocity was examined with a steady flow phantom. When assessed with steady flows in the phantom, flow velocities calculated by this method were in good agreement with velocities measured by a flow meter. This method was used with ECG gating to measure the blood flow of the right common carotid artery of a healthy volunteer. The measured peak flow velocity and the pattern of flow velocities during systole correlated well with the results obtained by Doppler ultrasound.

Blood Flow Velocity↗
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Lack of effect of gold salts on acetylcholine or histamine contraction of canine tracheal and bronchial smooth muscle.

In vitro gold salt incubation with proximal and distal canine airway smooth muscle was compared to untreated canine airway muscle with respect to histamine and acetylcholine-induced contraction. Gold chloride and gold sodium thiomalate had no effect on either proximal or distal canine airway smooth muscle agonist-induced contraction. Gold chloride in concentrations greater than 10(-5) M had a direct contractile effect. These results differ from previous studies which showed an inhibition of the histamine response of guinea-pig tracheal smooth muscle following in vitro preincubation with gold salts. This difference suggests that the mechanism(s) of the beneficial effects of long-term gold salt therapy on human asthma cannot be reliably studied with short-term in vitro animal preparations without first assessing species differences with respect to the effects of therapeutic agents. Human airway smooth muscle preparations would be the best means of addressing this question.

Acetylcholine↗
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Atlantoaxial subluxation. Radiography and magnetic resonance imaging correlated to myelopathy.

Twenty-nine patients with atlantoaxial subluxation (18 with rheumatoid arthritis, 2 due to trauma, 4 with os odontoideum, and one each with polyarteritis nodosa, rheumatic fever. Klippel-Feil syndrome, achondroplasia, and cause unknown) were evaluated using a 0.22 tesla resistive MRI unit. Cord compression was classified into four grades according to the degree on magnetic resonance imaging. There were 7 patients with no thecal sac compression (grade 0). 10 with a minimal degree of subarachnoid space compression without cord compression (grade 1), 7 with mild cord compression (grade 2), and 5 with severe cord compression or cord atrophy (grade 3). Although the severity of myelopathy showed poor correlation with the atlantodental interval on conventional radiography, high correlation was observed between MR grading and the degree of myelopathy. The high signal intensity foci were observed in 7 of 12 patients with cord compression (grades 2 and 3) on T2 weighted images. Other frequently observed findings in rheumatoid arthritis included soft tissue masses of low to intermediate signal intensity in the paraodontoid space, erosions of the odontoid processes, and atlantoaxial impaction on T1 and T2 weighted images.

Adolescent↗
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Rectangular field of view for dynamic MR imaging of sellar and parasellar regions.

The effectiveness and quality of a rectangular field of view (R-FOV) were compared with those of a square FOV (S-FOV) in dynamic MR study of sellar regions. Cranial nerves in the cavernous sinus were identified more clearly with R-FOV. The image quality grading of R-FOV was significantly superior to that of S-FOV.

Cavernous Sinus↗
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MR findings in two presumed cases of mild central pontine myelinolysis.

The authors describe two patients with presumed central pontine myelinolysis whose clinical symptoms were mild despite extensive intrapontine lesions evident on MR imaging. Enhancement of the lesions with Gd-DTPA was not observed in either case. It is suggested that the severity of findings on MR imaging does not necessarily reflect the severity of clinical symptoms of the disease.

Adult↗
PubMedDate not supplied

MR imaging of lingual carcinoma: comparison with surgical staging.

The purpose of this study was to determine the usefulness of magnetic resonance (MR) imaging for the preoperative staging of 18 patients with lingual carcinomas. Tumor stage as determined by MR imaging was compared with pathological stage. Conspicuity of tumors was compared among dynamic MR, T2-weighted, and postcontrast T1-weighted images. The tumor stage was evaluated correctly with MR imaging in 15/18 patients (83.3%). One patient was overstaged and two understaged due to incorrect diagnosis of size. In all T4 cases, tumor extension was diagnosed correctly. Dynamic MR and T2-weighted images were superior to postcontrast T1-weighted images in delineating and showing the extension of carcinomas. However, dynamic MR imaging showed no significant superiority to T2-weighted imaging. We conclude that MR imaging is of great value in the staging of lingual carcinoma. Dynamic study should be performed only when the lesion is undetectable or equivocal on T2-weighted imaging.

Adult↗
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Reconstruction of the inferior vena cava using a hepatic venous patch obtained from resected liver.

A 59-year-old woman with a 3 cm liver metastasis from rectal cancer underwent an extended right hepatic lobectomy with partial resection of the wall of the inferior vena cava. The metastasis was located behind the roots of the right and middle hepatic veins and involved the inferior vena cava. For reconstruction of the inferior vena cava, the intrahepatic middle hepatic vein, 2.5 cm in length, which was distant from the metastatic lesion, was removed from the resected liver. Then divided longitudinally to prepare a venous patch of 2.5 by 2.0 cm in size and applied to the defect. This technique facilitates reconstruction of the inferior vena cava without sacrificing other veins.

Female↗
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Spontaneous degeneration of testicular germ cells in congenitally athymic nude mice of four strains: a light microscopical observation.

Many hormonal studies have demonstrated that the presence of thymic factors affects testicular function. However, morphological studies on the testis in the absence of thymic factors are very limited. In the present study, seminiferous tubules of nude mice of four strains were light microscopically observed in order to investigate the effect of congenital athymia on germinal cell components. Testes obtained from congenitally athymic nude mice of CD1, BALB/c-nu/nu, LASAT, and KSN strains were fixed in Bouin's solution, dehydrated, and embedded in plastic. The samples were cut and their sections were stained with hematoxylin and eosin. The results showed that degeneration of testicular germ cells was focally observed in all four strains of athymic mice. The degenerating morphology was characterized by karyopyknosis and karyolysis of immature germ cells, multinuclear giant cell formation, and severe depletion of epithelial components with remaining Sertoli cells and/or some spermatogonia. KSN nude mice showed the most severe degenerative changes among the four strains of nude mice examined. Their significant degenerative changes first appeared at 2 weeks of age. In contrast, CD1 nude mice showed very slight degenerative features even at 20 weeks of age. BALB/c-nu/nu and LASAT nude mice had more degenerated epithelia than did CD1 nude mice; however, their significant degenerative changes were apparent at 20 but not at 10 weeks of age. Therefore, the severity and the onset of spontaneous degeneration and depletion of testicular germ cells in congenitally athymic mice were different among the four strains examined.

Animals↗