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Biomedical subjects

R Asato

Publications and source records attributed to R Asato.

At least 37 records · Page 2Linked to original sources
PubMed1993

Sustained uterine contractions: a cause of hypointense myometrial bulging.

Fifteen pregnant women were studied with magnetic resonance (MR) imaging. In 14 women, the myometrium exhibited distinct hypointense bulging on T2-weighted images that distorted the gestational sac and decidua but not the outer uterine coutour. In 12 women, an obvious discrepancy was observed between the inner myometrial configuration on T1-weighted images and that on intermediate and T2-weighted images. In three women who underwent serial T2-weighted studies separated by about 30 minutes during one MR examination, hypointense myometrial bulging was observed at a different site on each study. In two women who underwent follow-up MR study within a week after dilation and curettage, the previously distinct hypointense bulging completely disappeared. These findings confirm the transient and mobile nature of this myometrial bulging. This phenomenon can be attributed to sustained uterine contractions, which partially force the blood out of the uterus. The decrease in blood volume results in a decrease in water content, which accounts for the decrease in myometrial signal intensity on T2-weighted images.

Adult↗
PubMed1992

Nuclear magnetic resonance abnormalities of the cerebral white matter in children with acute lymphoblastic leukemia and malignant lymphoma during and after central nervous system prophylactic treatment with intrathecal methotrexate.

BACKGROUND: A prospective study was conducted to test the feasibility of nuclear magnetic resonance (NMR) imaging in the early diagnosis of treatment-induced leukoencephalopathy. METHODS: The study group included 16 patients with acute lymphoblastic leukemia and 4 patients with malignant lymphoma. All were given intravenous and intrathecal (IT) methotrexate (MTX) for central nervous system prophylaxis. Serial NMR studies were performed before and/or during induction-consolidation cycles. RESULTS: NMR imaging disclosed leukoencephalopathy in 8 of the 20 patients (40%) in the early stages of treatment. In six of the eight, the leukoencephalopathy was resolved after temporary or permanent interruption of IT MTX, and chemotherapy was completed successfully. The other two patients are being treated. Transient neurologic abnormalities developed in two of the eight patients. CONCLUSIONS: The possible causal relationship between leukoencephalopathy and the antimetabolic effects of MTX is discussed. This study clearly shows that NMR imaging is valuable in the early diagnosis and management of treatment-induced leukoencephalopathy.

Adolescent↗
PubMed1992

A case of treatment-related leukoencephalopathy: sequential MRI, CT and PET findings.

A case of treatment-related leukoencephalopathy is presented. A patient with medulloblastoma was postoperatively treated with craniospinal axis irradiation. One month after irradiation, weekly intrathecal administration of methotrexate was performed 4 times to treat cerebrospinal fluid dissemination of the tumor. Two months after the initiation of intrathecal chemotherapy, the patient became somnolent and developed decerebrate posturing. Magnetic resonance imaging showed diffuse leukoencephalopathy. Positron emission tomography revealed a diffuse decrease in glucose uptake in the deep white matter. Auditory evoked potential also showed diffuse abnormalities, not only in the cerebrum, but also in the brain stem. High dose intravenous leucovorin rescue was attempted without any neurologic improvement.

Blood Proteins↗
PubMed1992

Glial cyst of the pineal gland with characteristic computed tomography, magnetic resonance imaging, and pathological findings: report of two cases.

Two cases of glial cyst of the pineal gland are documented. Preoperative computed tomography and magnetic resonance imaging revealed cystic lesions of the pineal region with contrast enhancement of the walls, suggesting neoplastic lesions rather than true cysts. However, the histopathological examination of the resected specimens revealed the presence of glial tissue and normal structure of pineal gland and capsule, characteristics that were consistent with those of glial cysts of the pineal gland. Headache and visual disturbance were resolved after total removal of the cysts.

Adolescent↗
PubMed1992

Degeneration of the ipsilateral substantia nigra following cerebral infarction in the striatum.

BACKGROUND AND PURPOSE: In rats, degeneration of the ipsilateral substantia nigra occurs a few weeks after occlusion of the middle cerebral artery. The aim of this study was to clarify whether similar change is observed in stroke patients. METHODS: Eighteen patients with striatal infarction and six patients with cortical infarction in the territory of the middle cerebral artery were examined by means of sequential magnetic resonance imaging. RESULTS: In all patients with striatal infarction, T2-weighted images revealed a high-signal-intensity spot in the ipsilateral substantia nigra. Changes in the ipsilateral substantial nigra appeared at day 14 after stroke on average and then became less intense and smaller a few months after the stroke. By contrast, we observed no nigral changes in any patient with cortical infarction. CONCLUSIONS: The degenerative change in the ipsilateral substantia nigra initially found in the rat model similarly occurred in patients with striatal infarction. This remote change in the substantia nigra may represent magnetic resonance imaging detection of neuropathologic changes in this region through the striatonigral pathway.

Aged↗
PubMed1992

Age-related prevalence of Strongyloides stercoralis infection in Okinawa, Japan.

Age-prevalence of Strongyloides stercoralis infection was studied in six areas of Okinawa, Japan. In all localities, most of the infected inhabitants were aged over 40 years of age and females were less infected than males. The peak prevalence was found in inhabitants in their fifties in high endemic groups and shifted to higher age in lower endemic groups. This age-prevalence pattern resembles more that of schistosome infections than that of other gastrointestinal helminthic infections.

Adolescent↗
PubMed1992

Is the prevalence of HTLV-1 infection higher in Strongyloides carriers than in non-carriers?

To assess the concomitance of strongyloidiasis and HTLV-1 infection, an epidemiological survey was conducted in Okinawa, Japan, using the agar-plate culture, a highly sensitive method for detection of Strongyloides stercoralis. No significant difference in the positive rate of anti-HTLV-1 antibody was found between Strongyloides carriers and non-carriers. This result suggests that these two infections occur independently.

Adolescent↗
PubMed1992

Epidemiological aspects of Strongyloides stercoralis infection in Okinawa, Japan.

The epidemiology of Strongyloides stercoralis infection was compared among three localities with various prevalences of human T lymphotropic virus type 1 (HTLV-1) infection in Okinawa Prefecture, Japan, using agar-plate culture of faeces. The prevalence of S. stercoralis infection is much higher in Gusukube, where HTLV-1 infection is rare, than in Yomitan, where this viral infection is common. In all localities the parasite prevalence is significantly higher in males than in females, whereas the prevalence of HTLV-1 infection is much higher in females. These epidemiological facts suggest that infection by S. stercoralis occurs independently of that by HTLV-1.

Adolescent↗
PubMed1991

Magnetic resonance imaging of neurohypophyseal germinomas.

The authors reviewed magnetic resonance (MR) images in seven cases of germinoma in the hypothalamoneurohypophyseal axis (HNA). The intrasellar portions were clearly identified in six germinomas. Two small germinomas of these six were located only in the neurohypophysis. The major parts of the four large germinomas were located below the optic chiasm, and the large intrasellar portions were demonstrated. The remaining one small germinoma was localized from the pituitary stalk to the third ventricular floor. These findings strongly suggest that the primary site of germinomas in the HNA is the neurohypophysis. In the four large germinomas, the tumor shape was similar to that of pituitary adenoma. The authors believe that age (limited to first three decades), symptoms (diabetes insipidus), MR findings (absence of normal hyperintense signal of the posterior pituitary on T1-weighted (T1WI) images, and homogeneous hypointensity to the pons on T1WI images/isointensity on T2-weighted images are important in differential diagnosis.

Adolescent↗
PubMed1991

[Clinical study on ivermectin against Strongyloides stercoralis].

We previously reported the efficacy of ivermectin (IVM) for the treatment of 23 strongyloidiasis patients. We now reported the efficacy and safety of IVM therapy on 54 patients. Fifty-four patients, 28 males and 26 females, received a single oral dose of IVM one hour before breakfast and this treatment was repeated 2 weeks later. The following results were obtained: 1) The cure rate at 2 weeks after the initial treatment was 92.5% (49 of 53 patients) and 2 weeks after the second course was 96.0% (48 of 50 patients). 2) Four patients (7.4%) complained of diarrhea (n = 2 patients), constipation (n = 1), borborygmus (n = 1), dizziness (n = 1), diplopia (n = 1) and peri-anal itching (n = 1) after the first treatment. Three patients (5.6%) complained of borborygmus (n = 1), itching (n = 1) and exanthema (n = 1) after the second treatment. But all symptoms were mild and required no treatment and subsided in a few days. 3) Positive rate of HTLV-1 antibody was 25.9% in the patients. As described above, although side effects occurred in some cases, they were mild and transient. From these results, we concluded that IVM is an effective drug for strongyloidiasis.

Adult↗
PubMed1991

[Treatment of strongyloidiasis with mebendazole--long-term eradication and new trials].

We previously reported the short period cure rate of mebendazole (MBZ) treatment to strongyloidiasis. We are now reporting the long period cure rate of the treatment. The results were as follows: 1) The cure rate was 73.9% (17/23) in single use of MBZ (100 mg twice daily for 28 days). 2) The cure rate was 100.0% (22/22) in combination therapy (thiabendazole 500 mg three times a day for 5 days and after that, MBZ 100 mg twice daily for 9 days). Before we obtained the cure rate of 6 months after the treatment described above, we concluded that MBZ could be used for the treatment of strongyloides infection because of the lack of severe side effects and suitable intervals between courses would prevent liver injury. Thus, in this study, 47 patients were treated with 100 mg of MBZ twice a day for 5 days and this treatment was repeated 1, 3 and 4 weeks later on the same schedules (group 1). But because of liver injury, 13 patients were interrupted and moved to the 4th course (group 2). The following results were obtained: 1) Out of a total of 60 patients, the cure rate was 88.1% (52/59) after 2 courses, 92.3% (12/13) after 3 courses and 100.0% (46/46) after the 4 courses were finished. 2) Diarrhea (10.6%), arthralgia and lumbago (8.5%) were observed in group 1. No side effects were observed in group 2. 3) The incidence of liver injury occurred 48.9% (23/47) in group 1 and 30.8% (4/13) in group 2. 4) Positive rate of HTLV-I antibody was 40.0% (24/60).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Magnetic resonance imaging in relation to EEG epileptic foci in tuberous sclerosis.

In 20 patients with tuberous sclerosis (TS), who were sequentially treated for epilepsy at our clinic, the high signal lesions in the cerebral cortex and subcortex detected on T2 weighted magnetic resonance imaging (MRI) were compared with the interictal EEG findings. In four cases who showed a unilateral distribution of the MRI lesions, there was a good correlation between the laterality of the affected lobes and the localization of the EEG epileptic foci. Thirteen cases with more than four affected lobes in both hemispheres also showed bilateral epileptic foci on EEG. The MRI lesions in the occipital lobes showed the best correlation with the EEG epileptic foci, while the worst correlation was seen in the frontal lobes. In addition, the cases with four or more affected lobes without laterality on MRI are more likely to show bilateral synchronization on EEG. The prognosis of epilepsy in these cases was found to be rather poor.

Adolescent↗
PubMed1990

[Treatment of strongyloidiasis with mebendazole and its combination with thiabendazole].

Although Strongyloides stercoralis (S. stercoralis) infection rate in Okinawa Prefecture was less than 2% by the traditional method, it has been proven to be 6.2% by the new technique--agar plate method. Thiabendazole has strong activity to eradicate the organism, but it is well known that the rate of severe side effects is extremely high. Therefore, we attempted to evaluate the new treatment for the infection by mebendazole and its combination with thiabendazole. The reason for use of the drug is based on the reports of successful treatment of S. stercoralis infection in humans with the mild and infrequent side effects produced by the drug. Thirty three patients were orally given mebendazole 100 mg twice daily for 28 days. Twenty six patients were given thiabendazole 500 mg thrice daily for 5 days and after that, mebendazole 100 mg twice daily for 9 days. This combination therapy was repeated twice. The following results were obtained: 1) Out of a total of 59 patients, the cure rate was 83.3% (20/24) in single use of mebendazole and 100.0% (22/22) in the combination therapy. 2) Constipation (9.1%) and headache (9.1%) were of relatively high incidence in the mebendazole group, but they were mild. Nausea (19.2%) and headache (15.4%) were observed in the combination therapy group and the drug was discontinued in 2 patients. 3) The incidence of the elevation of S-GOT, S-GPT was noted in 71.4% (20/28) for the mebendazole group and 52.2% (12/23) for combination therapy group. All 13 patients of the mebendazole group were negative in lymphocyte stimulation test for mebendazole.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Gallbladder carcinoma: evaluation with MR imaging.

Magnetic resonance (MR) images of 19 patients with histologically proved gallbladder carcinoma were retrospectively reviewed to determine the appearance of the primary tumor, and to assess the ability of MR imaging to demonstrate the various modes of tumor spread beyond the gallbladder. The primary tumor, as well as tumor spread beyond the gallbladder, was hyperintense on T2-weighted images and hypointense on T1-weighted images when compared with the liver parenchyma. Liver invasion and metastasis could be depicted by MR imaging with both sequences, unless the tumors were small or the extent of invasion was minimal. Duodenal invasion was difficult to evaluate because of motion artifacts, paucity of fat, and partial volume effects. T1-weighted images readily demonstrated extension of the tumor to the hepatoduodenal ligament and para-aortic region with good contrast between tumor and surrounding tissue. The extent of tumor extension to the blood vessels was also easily evaluated because of flow void in the vasculature. MR imaging can help determine the extent of gallbladder carcinoma and can contribute to the staging of this disease.

Adenocarcinoma↗
PubMed1990

[Intraluminal thrombosis and growth-mechanism of giant intracranial aneurysms].

12 giant intracranial aneurysms were studied by MRI. Intraluminal thrombosis was observed in 9 aneurysms. Thrombosis was found more frequently in larger aneurysms. Thrombi were formed posteriorly or inferiorly in the lumen of 4 among 5 IC-cavernous aneurysms. Location of the neck of the aneurysms and stagnation of blood flow influenced by gravity may be causative factors determining the location of thrombi. In 6 aneurysms intraluminal thrombi were inhomogeneous on MRI, suggesting that the thrombi had been formed at different times. New thrombi were formed between the aneurysmal wall and the old thrombus in 3 cases. Dissection of the aneurysmal wall by residual blood flow in the lumen or hemorrhage in the aneurysmal wall may be one of the growth mechanisms of giant intracranial aneurysms.

Adolescent↗