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Biomedical subjects

S Shimizu

Publications and source records attributed to S Shimizu.

At least 127 records · Page 7Linked to original sources
PubMed2001

Rupture of pial arteriovenous malformation associated with early thrombosis of the draining system following stereotactic radiosurgery--case report.

A 50-year-old man was treated with stereotactic gamma knife radiosurgery for an incidentally detected small callosal arteriovenous malformation (AVM) with stenosis of the main draining pathway. He suffered two episodes of intraventricular hemorrhage at 4 and 14 weeks after the radiosurgery. Radiological studies demonstrated that the anterior portion of the draining system including a varix, which had been irradiated, was thrombosed before the obliteration of arteriovenous shunts. Stereotactic radiosurgery is an accepted treatment for selected small and medium AVMs, but this procedure may increase the risk of bleeding. Early occlusion of a part of the draining pathway after stereotactic radiosurgery might have induced AVM rupture. An impaired venous outlet, either consisting of one draining vein or with stenosis, present before treatment may be develop thrombosis in response to high-dose irradiation.

Aneurysm, Ruptured↗
PubMed2001

Increased arterial wall stiffness limits flow volume in the lower extremities in type 2 diabetic patients.

OBJECTIVE: To document an association between arterial wall stiffness and reduced flow volume in the lower-extremity arteries of diabetic patients. RESEARCH DESIGN AND METHODS: We recruited 60 consecutive type 2 diabetic patients who had no history or symptoms of peripheral arterial disease (PAD) in the lower extremities and normal ankle/brachial systolic blood pressure index at the time of the study (non-PAD group) and 20 age-matched nondiabetic subjects (control group). We used an automatic device to measure pulse wave velocity (PWV) in the lower extremities as an index of arterial wall stiffness. At the popliteal artery, we evaluated flow volume and the resistive index as an index of arterial resistance to blood flow using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. RESULTS: Consistent with previous reports, we confirmed that the non-PAD group had an abnormally higher PWV compared with that of the control group (P < 0.001). To further demonstrate decreased flow volume and abnormal flow pattern at the popliteal artery in patients with a higher degree of arterial wall stiffness, we assigned the 60 non-PAD patients to tertiles based on their levels of PWV. In the highest group, magnetic resonance angiograms of the calf and foot arteries showed decreased intravascular signal intensity, indicating the decreased arterial inflow in those arteries. The highest group was also characterized by the lowest late diastolic and total flow volumes as well as the highest resistive index among the groups. From stepwise multiple regression analysis, PWV and autonomic function were identified as independent determinants for late diastolic flow volume (r(2) = 0.300; P < 0.001). CONCLUSIONS: Arterial wall stiffness was associated with reduced arterial flow volume in the lower extremities of diabetic patients.

Aged↗
PubMed2001

[An elderly case of lung cancer presenting with symptoms of orbital metastasis].

An 88-year-old woman was first referred to an eye clinic in mid-May 2000 because of limitation of ocular movement. A right orbital tumor was recognized on orbital CT scans and she was referred to our hospital. A chest X-ray film showed an abnormal mass in the right middle lung field, so she was admitted for further investigations. Adenocarcinoma was diagnosed by transbronchial lung biopsy. The right orbital tumor was thought to be a metastasis from the lung cancer. She received radiation therapy for the metastatic orbital tumor. However, two months after the onset of symptoms, she died due to progressive systemic metastasis. In summary, we report an elderly lung cancer patient whose initial symptoms were related to orbital metastasis.

Adenocarcinoma↗
PubMed2001

Relationship between morbidity and body mass index of mariners in the Japan Maritime Self-Defense Force Fleet Escort Force.

To establish a practical weight management program for mariners in the Japan Maritime Self-Defense Force (JMSDF) Fleet Escort Force, the relationship between morbidity and body mass index (BMI) was studied. To estimate morbidity, 10 medical problems were used as indices (hyperlipidemia, hyperuricemia, diabetes mellitus, lung disease, heart disease, upper gastrointestinal tract disease, hypertension, renal disease, liver disease, and anemia). A curvilinear relationship was found between morbidity and BMI, in which a BMI of 17.5 was associated with the lowest morbidity. This curvilinear pattern was more complex than a curve reported previously for Japanese civilians. Using the present curve and aiming for a BMI of 17.5 will help in the design and implementation of a practical management program for health promotion in the JMSDF.

Adipose Tissue↗
PubMed2001

[The association between emergency clinic visits for asthmatic attacks and fluctuating environmental factors].

The number of nocturnal visits of asthmatic attack patients to the emergency room of Yokohama Medical Association's Clinic from January 1990 to December 1991 was compared to daily levels of air pollution (NO, NO2, SO2 and SPM) and weather (temperature and relative humidity) variables measured in Yokohama City. Trend-cycle components (Trend) that control for the weekly effects, other irregular variance for asthmatic attack incidence and environmental parameter measurements were estimated from the original data series using the method of Akaike and Ishiguro (1980). The rate of increase for each environmental parameter was then calculated from its trend-cycle components. We classified the data into four stages on the basis of rising and falling temperature and humidity. For each stage of temperature and humidity, fluctuation we estimated correlations between the number of asthmatic attack visits and original data series measurements, estimated trend-cycle components, and calculated rates of increase for each of the air pollutants. The daily number of asthmatic attack visits was negatively correlated to the daily mean values of all air pollutants, but positively correlated to the daily mean temperature and relative humidity. The trend-cycle components of the air pollutants were also negatively correlated to the frequencies of asthmatic attacks (p < 0.01 for all pollutants except NO2). In contrast, the number of asthmatic attack visits were in general positively correlated with increasing levels of pollutants. Furthermore, when both temperature and relative humidity decreased, significant correlations (r > 0.31, p < 0.001) between the number of asthmatic attacks and increased rates of all air pollutants were observed (r: NO2 > NO > SO2 > SPM).

Air Pollutants↗
PubMed2001

[The relationships between the prevalence of asthmatic symptoms and environmental factors].

The relationships between the prevalence of asthmatic symptoms and environmental factors were evaluated using a modified version of the Japanese ATS-DLD children's questionnaire. The questionnaire was distributed to 13,306 students in 3 areas of Yokohama City; in 1986 (4705), 1988 (4440), and 1991 (4161). The results indicate: 1. The prevalence of asthmatic symptoms among boys increased slightly from 1986 (9.2%) to 1991 (9.6%), but no increase was observed that among girls (5.7%). The overall prevalence among boys was 1.7 times higher than that among girls. 2. On the whole, the air pollution level was Tsurumi-ku > Naka-ku > Midori-ku. But the prevalence of asthmatic symptoms among boys was Naka-ku > Tsurumi-ku > Midori-ku in 1986, 1988 and 1991. The prevalence among girls was the same result in 1986, but in 1988 and 1991, it was Tsurumi-ku > Naka-ku > Midori-ku. 3. In the longitudinal study of the same group, the prevalence of asthmatic symptoms among boys decreased between 5th and 6th grade. In contrast, remission of asthma increased between 5th and 6th grade. And the prevalence of asthmatic symptoms among girls decreased between 3rd and 6th grade. In contrast, remission of asthma increased between 3rd and 6th grade. 4. Children who had a personal or family history of allergic diseases, allergic disposition, respiratory diseases before 2 years old, wheezing or difficulty in breathing, or allergies against foods or medicines, showed a statistically significant Odds ratio (p < 0.01) for asthmatic symptoms.

Air Pollution↗
PubMed2001

[A pediatric case of intractable complex partial seizures associated with mesial temporal lobe astrocytoma: usefulness of interictal epileptiform discharges in the present case].

The patient was a 10-year-old male with normal developmental milestones. He had medically intractable complex partial seizures since the age of 7 years. At the age of 10 years, he had focal motor seizures of the right face, and a head CT scan showed a calcified lesion in the left mesial temporal region. The tumor exhibited low intensity on T 1-weighted and high intensity on T 2-weighted MR images, and was not enhanced by gadolinium-diethylenetriamine pentaacetic acid. Interictal SPECT showed hypoperfusion in the left temporal region. One-day video/EEG monitoring revealed very frequent epileptiform discharges which occurred only during sleep period exclusively in the left anterior-to-middle temporal region. The patient underwent lesionectomy with the guidance of electrocorticography. The histological study of the resected tissue showed astrocytoma. After surgery he has had no seizures for 10 months. It was concluded that very frequent interictal epileptiform discharges strictly localized to the temporal lobe at which MRI-identified tumor was present could be predictive of epileptogenic zone in the present patient in whom clinical symptoms and the results of other studies were also concordant.

Astrocytoma↗
PubMed2001

[Changes in the prevalence of asthma-like symptoms and risk factors in school children in Yokohama from 1986 to 1991].

We conducted a questionnaire survey of first graders from six elementary schools in three areas of Yokohama annually from 1986 to 1991 (about 700 children each year) to investigate the changes in prevalence of asthma-like symptoms and association with potential risk factors. The prevalence rate of asthma-like symptoms increased from 7.6% to 11.0% in boys and from 6.5% to 8.8% in girls from 1986 to 1991. The ratio of affected boys was consistently higher than that in girls, but there were no significant regional differences. We found statistically significant odds ratios for the effect of a previous history of allergies, respiratory disease before age two, wheezing or difficulty in breath before age two and cough without respiratory tract infections on the prevalence of asthma-like symptoms.

Asthma↗
PubMed2000

Efficiency of absorption and metabolic conversion of quercetin and its glucosides in human intestinal cell line Caco-2.

The efficiency of intestinal absorption and metabolic conversion of quercetin aglycone and its glucosides, quercetin-4'-O-beta-D-glucoside (Q4'G), quercetin-3-O-beta-D-glucoside (Q3G), and quercetin-3,4'-di-O-beta-D-glucoside (Q3,4'G), was estimated by using Caco-2 cell monolayers as an intestinal epithelial cell model. Aglycone was significantly lost from the apical side, resulting in the appearance of free and conjugated forms of quercetin and those of isorhamnetin in the cellular extracts. In the basolateral solution, the conjugated form of quercetin was predominant and increased with the elapse of incubation. As compared with quercetin aglycone, none of the quercetin glucosides were absorbed efficiently from apical side. However, Q4'G yielded conjugated quercetin and isorhamnetin in basolateral solution at higher amounts than Q3G or Q3,4'G. Lipophilicity of Q4'G was found to be higher than that of Q3G or Q3,4'G. This suggests that lipophilicity contributes to the relatively efficient absorption of Q4'G. It is likely that the occurrence of hydrolysis enhances the efficiency of intestinal absorption and metabolic conversion of dietary quercetin glucosides.

Caco-2 Cells↗
PubMed2000

Reversible and potent uncoupling of hog gastric (H(+)+K(+))-ATPase by prodigiosins.

Prodigiosin, prodigiosin 25-C, and metacycloprodigiosin all strongly inhibited the acidification activity of (H(+)+K(+))-ATPase on membrane vesicles from hog gastric mucosa (IC(50) = 32 to 103 pmol/mg protein). But, the prodigiosins, unlike omeprazole, showed little inhibitory effect on K(+)-dependent ATPase (K(+)-ATPase) activity, although at higher concentrations they inhibited K(+)-ATPase activity with an IC(50) of 1.5 to 3.0 microM. Furthermore, the inhibitory effect of the prodigiosins was rapid and completely reversible unlike that of omeprazole, and the mode of inhibition was non-competitive with respect to ATP. Hog gastric (H(+)+K(+))-ATPase itself showed an absolute requirement of halide (effectively, chloride) for acidification activity. Prodigiosins also showed a chloride requirement for inhibition of vesicular acidification, and quickly reversed the acidification of vesicular pH to neutrality even in the presence of N, N'-dicyclohexylcarbodiimide (DCCD), showing their ionophoric nature of acidification inhibitory activity. In fact, tributyltin chloride (TBT, an OH(-)/Cl(-) exchange ionophore) also inhibited vesicular acidification, but it inhibited K(+)-ATPase activity too. Finally, the prodigiosins inhibited the acid secretion from parietal cells isolated from rabbit gastric mucosa. These results suggest that prodigiosins are potent reversible uncouplers of (H(+)+K(+))-ATPase that inhibit gastric acid secretion.

Adenosine Triphosphate↗
PubMed2000

Use of an implanted marker and real-time tracking of the marker for the positioning of prostate and bladder cancers.

PURPOSE: A real-time tracking radiotherapy was investigated to assess its usefulness in precise localization and verification of prostate and bladder cancers. METHODS AND MATERIALS: The real-time tracking radiation therapy (RTRT) system consists of implantation of a 2.0-mm gold marker into a clinical target volume (CTV), three-dimensional radiation treatment planning (3DRTP) system, and the use of two sets of diagnostic x-ray television systems in the linear accelerator room, image processing units, and an image display unit. The position of the patient can be corrected by adjusting the actual marker position to the planned marker position, which has been transferred from the 3DRTP and superimposed on the fluoroscopic image on the display unit of the RTRT system. The position of the markers can be visualized during irradiation and after treatment delivery to verify the accuracy of the localization. Ten patients with prostate cancer and 5 patients with bladder cancer were examined using this system for the treatment setup on 91 occasions. RESULTS: After manual setup using skin markers, the median of absolute value of discrepancies between the actual position of the marker and the planned position of the marker for prostate cancer was 3.4 (0.1-8.9) mm, 4.1 (0.2-18.1) mm, and 2.3 (0.0-10.6) mm for the lateral, anteroposterior, and craniocaudal directions, respectively. The 3D median distance between the actual and planned positions of the marker was 6.9 (1.1-18.2) mm for prostate cancer and 6.9 (1.7-18.6) mm for bladder cancer. After relocation using RTRT, the 3D distance between the actual and planned position of the marker was 0.9 +/- 0.9 mm. Median 3D distances between actual positions after treatment delivery and planned positions were 1.6 (0.0-6.3) mm and 2.0 (0.5-8.0) mm during daily radiotherapy for the marker in patients with prostate cancer and bladder cancer, respectively. CONCLUSION: We believe the new positioning system can reduce uncertainty due to setup error and internal organ motion, although further improvement is needed for the system to account for the rotational and elastic changes of the affected tissues.

Humans↗
PubMed2000

Physical aspects of a real-time tumor-tracking system for gated radiotherapy.

PURPOSE: To reduce uncertainty due to setup error and organ motion during radiotherapy of tumors in or near the lung, by means of real-time tumor tracking and gating of a linear accelerator. METHODS AND MATERIALS: The real-time tumor-tracking system consists of four sets of diagnostic X-ray television systems (two of which offer an unobstructed view of the patient at any time), an image processor unit, a gating control unit, and an image display unit. The system recognizes the position of a 2.0-mm gold marker in the human body 30 times per second using two X-ray television systems. The marker is inserted in or near the tumor using image guided implantation. The linear accelerator is gated to irradiate the tumor only when the marker is within a given tolerance from its planned coordinates relative to the isocenter. The accuracy of the system and the additional dose due to the diagnostic X-ray were examined in a phantom, and the geometric performance of the system was evaluated in 4 patients. RESULTS: The phantom experiment demonstrated that the geometric accuracy of the tumor-tracking system is better than 1.5 mm for moving targets up to a speed of 40 mm/s. The dose due to the diagnostic X-ray monitoring ranged from 0.01% to 1% of the target dose for a 2.0-Gy irradiation of a chest phantom. In 4 patients with lung cancer, the range of the coordinates of the tumor marker during irradiation was 2.5-5.3 mm, which would have been 9.6-38.4 mm without tracking. CONCLUSION: We successfully implemented and applied a tumor-tracking and gating system. The system significantly improves the accuracy of irradiation of targets in motion at the expense of an acceptable amount of diagnostic X-ray exposure.

Algorithms↗
PubMed2000

A novel gene, MEL1, mapped to 1p36.3 is highly homologous to the MDS1/EVI1 gene and is transcriptionally activated in t(1;3)(p36;q21)-positive leukemia cells.

The reciprocal translocation t(1;3)(p36;q21) occurs in a subset of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), which is frequently characterized by trilineage dysplasia, in particular dysmegakaryocytopoiesis, and poor prognosis. Previously, the breakpoint cluster region (BCR) at 3q21 was identified within a 60-kilobase (kb) region centromeric to the BCR of 3q21q26 syndrome and that at 1p36.3 within a 90-kb region. In this study, genes were searched near the breakpoints at 1p36.3, and a novel gene was isolated that encoded a zinc finger protein with a PR domain, which is highly homologous to the MDS1/EVI1 gene. The novel gene, designated as MEL1 (MDS1/EVI1-like gene 1), with 1257 amino acid residues is 64% similar in nucleotide and 63% similar in amino acid sequences to MDS1/EVI1 with the same domain structure. The MEL1 gene is expressed in leukemia cells with t(1;3) but not in other cell lines or bone marrow, spleen, and fetal liver, suggesting that MEL1 is specifically in the t(1;3)(p36;q21)-positive MDS/AML. On the basis of the positional relationship between the EVI1 and MEL1 genes in each translocation, it was suggested that both genes are transcriptionally activated by the translocation of the 3q21 region with the Ribophorin I gene. Because of the transcriptional activation of the EVI1 family genes in both t(1;3)(p36;q21)-positive MDS/AML and 3q21q26 syndrome, it is suggested that they share a common molecular mechanism for the leukemogenic transformation of the cells.

Amino Acid Sequence↗
PubMed2000

Human gelsolin prevents apoptosis by inhibiting apoptotic mitochondrial changes via closing VDAC.

Gelsolin is a Ca2+-dependent actin-regulatory protein that modulates actin assembly and disassembly, and is believed to regulate cell motility through modulation of the actin network. Gelsolin was also recently suggested to be involved in the regulation of apoptosis: human gelsolin (hGsn) has anti-apoptotic activity, whereas mouse gelsolin (mGsn) exerts either proapoptotic or anti-apoptotic activity depending on different cell types. Here, we studied the basis of anti-apoptotic activity of hGsn. We showed that both endogenous and overexpressed hGsn has anti-apoptotic activity, that depends on its C-terminal half. We also found that hGsn and its C-terminal half but not mGsn could prevent apoptotic mitochondrial changes such as Apsi loss and cytochrome c release in isolated mitochondria to a similar extent as Bcl-xL, indicating that hGsn targets the mitochondria to prevent apoptosis via its C-terminal half. In the same way as anti-apoptotic Bcl-xL, which we recently found to prevent apoptotic mitochondrial changes by binding and closing the voltage-dependent anion channel (VDAC), hGsn and its C-terminal half inhibited the activity of VDAC on liposomes through direct binding in a Ca2+-dependent manner. These results suggest that hGsn inhibits apoptosis by blocking mitochondrial VDAC activity.

3T3 Cells↗
PubMed2000

Reduction in tick numbers (Haemaphysalis longicornis), mortality and incidence of Theileria sergenti infection in field-grazed calves treated with flumethrin pour-on.

The effectiveness of the pour-on formulation of flumethrin was tested on grazing cattle. Flumethrin was applied once a month from April to October from 1990 to 1995 to cattle grazing in the Aso area of Kumamoto Prefecture in Japan. Both the number of ticks in the field and the number of ticks feeding on cattle decreased remarkably in relation to the number of years flumethrin was applied. Ticks in the field were not detected in 1994 and 1995, and ticks feeding on cattle decreased to 4% in 1995. Mortality due to Theileria sergenti infection also decreased significantly after more than 3 years of flumethrin pour-on application, although overall mortality did not change. At the end of the trial the incidence of T. sergenti had decreased to one-fifth of the pretrial value, although total incidence of disease had not changed. These results indicated that multiple-year seasonal application of flumethrin pour-on to grazing cattle effectively decreased the number of ticks and decreased both mortality and incidence of T. sergenti.

Administration, Topical↗
PubMed2000

Bax and Bcl-xL independently regulate apoptotic changes of yeast mitochondria that require VDAC but not adenine nucleotide translocator.

Mitochondria play an essential role in apoptosis by releasing apoptogenic molecules such as cytochrome c and AIF, and some caspases, which are all regulated by Bcl-2 family proteins. Pro-apoptotic Bax and Bak have been shown to induce cytochrome c release and loss of membrane potential (Deltapsi) leading to AIF release in the isolated mitochondria. We have previously shown that Bax and Bak open the voltage-dependent anion channel (VDAC) allowing cytochrome c to pass through the channel, and Bcl-xL closes the channel. However, it has been reported that it is adenine nucleotide translocator (ANT) with which Bax/Bcl-xL interacts that modulate the channel activity. Here, we investigated the role of ANT and VDAC in the changes of isolated mitochondria triggered by Bax and by chemicals that induce permeability transition (PT). In rat and yeast mitochondria, Bax did not affect the ADP/ATP exchange activity of ANT. VDAC-deficient but not ANT-deficient yeast mitochondria showed resistance to cytochrome c release, Deltapsi loss, and swelling caused by Bax and PT inducers. Bcl-xL showed similar inhibition of all these changes in ANT-deficient and wild type yeast mitochondria. Furthermore, Bax induces cytochrome c release in wild type yeast cells but not VDAC1-deficient yeast cells. These data indicate that VDAC, but not ANT, is essential for apoptotic mitochondrial changes. The data also indicate that Bcl-xL and Bax possess an ability to regulate mitochondrial membrane permeability independently of other Bcl-2 family members.

Adenosine Triphosphate↗