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Biomedical subjects

J Hosaka

Publications and source records attributed to J Hosaka.

At least 19 recordsLinked to original sources
PubMed2006

Improved search for nu(mu) --> nu(e) oscillation in a long-baseline accelerator experiment.

We performed an improved search for nu(mu) --> nu(e) oscillation with the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment, using the full data sample of 9.2 x 10(19) protons on target. No evidence for a nu(e) appearance signal was found, and we set bounds on the nu(mu) --> nu(e) oscillation parameters. At Deltam(2)=2.8 x 10(-3) eV(2), the best-fit value of the K2Knu(mu) disappearance analysis, we set an upper limit of sin(2)2theta(mue) < 0.13 at a 90% confidence level.

Journal Article↗
PubMed2005

Search for coherent charged pion production in neutrino-carbon interactions.

We report the result from a search for charged-current coherent pion production induced by muon neutrinos with a mean energy of 1.3 GeV. The data are collected with a fully active scintillator detector in the K2K long-baseline neutrino oscillation experiment. No evidence for coherent pion production is observed, and an upper limit of is set on the cross section ratio of coherent pion production to the total charged-current interaction at 90% confidence level. This is the first experimental limit for coherent charged pion production in the energy region of a few GeV.

Journal Article↗
PubMed2005

Evidence for muon neutrino oscillation in an accelerator-based experiment.

We present results for nu(mu) oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced nu(mu) beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy-dependent disappearance of nu(mu), which we presume have oscillated to nu(tau). The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).

Journal Article↗
PubMed2004

Evidence for an oscillatory signature in atmospheric neutrino oscillations.

Muon neutrino disappearance probability as a function of neutrino flight length L over neutrino energy E was studied. A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed L/E distribution constrained nu(micro)<-->nu(tau) neutrino oscillation parameters; 1.9x10(-3) 0.90 at 90% confidence level.

Journal Article↗
PubMed2003

[Successful total arch replacement for a 92-year-old woman with acute Stanford A aortic dissection: report of a case].

We reported a successful case of emergent total arch replacement for a nonagenarian with acute Stanford A aortic dissection. A 92-year-old woman complained of general fatigue, with hypotension. Echocardiography showed moderate pericardial effusion and aortic regurgitation. Computed tomography (CT) scan showed widely extended aortic dissection from the ascending aorta to descending thoracic aorta, and cardiac tamponade. An emergent total arch replacement was performed under hypothermic selective cerebral perfusion with bladder temperature of 22.5 degrees C. Although she suffered from pneumothorax, renal insufficiency and gastrointestinal (GI) bleeding postoperatively, she tolerated the operation and complications, well. She is now leading a good life with the same level of activities of daily living (ADL) as preoperative one.

Activities of Daily Living↗
PubMed1999

Optimal blood flow for cooled brain at 20 degrees C.

BACKGROUND: Optimal conditions for deep hypothermic perfusion and protective brain blood flow remain unclear. METHODS: Dogs (n = 52) underwent 120 minutes of cardiopulmonary bypass at 20 degrees C with perfusion flow rates of 2.5, 5, 10, 20, 40, and 100 mL x kg(-1) x min(-1). We examined the effect of the various flow rates and different perfusion pressures on brain blood flow, metabolism, and intracellular pH. RESULTS: The brain was ischemic and acidotic when the perfusion flow rate was less than 5 mL kg(-1) x min(-1) and pressure was less than 10 mm Hg. When perfusion pressure was higher than 10 mm Hg, cerebral cortex blood flow was more than 9 mL x 100 g(-1) x min(-1) and intracellular pH, higher than 6.95. The cerebral metabolic rate for oxygen decreased at a flow rate of 2.5 mL x kg(-1) min(-1). The cerebral metabolic ratio of glucose to oxygen and the cerebral vascular resistance were lowest when perfusion pressure was 10 to 30 mm Hg. Full-flow (100 mL x kg(-1) x min(-1)) perfusion caused paradoxical brain acidosis; a flow of 40 mL x kg(-1) x min(-1) provided the best results. CONCLUSIONS: Both extremely low-flow perfusion and excessive perfusion cause brain acidosis. Low-flow perfusion at a pressure of 20 mm Hg provides cerebral vasorelaxation and aerobic metabolism during operations at 20 degrees C.

Animals↗
PubMed1999

In vivo evaluation of the adjustable temporary venous spring filter and the RF02 temporary filter: comparative study.

RATIONALE AND OBJECTIVES: The authors performed this study to compare the in vivo efficacies of the temporary venous spring filter and the RF02 filter in an animal model. MATERIALS AND METHODS: Either the spring filter or the RF02 filter was placed in the inferior vena cava of 10 pigs each, and two clots (5 x 20 mm) were funneled into the filters at 1-hour intervals. The second clots were funneled without removing the first clots captured by the filters. Clot-trapping ability, caval occlusion associated with the clot-trapping procedure, arterial blood gas concentrations, and changes in arterial and iliac venous pressures were evaluated. RESULTS: Placement of the RF02 filter caused elevation of iliac venous pressure with a maximum of 2.2 mm Hg (median) (n = 13, P = .003). Placement of the spring filter parallel to venous flow enabled capture of 90% (nine of 10) and 100% (six of six) of the first and second clots, respectively. The RF02 filter captured clots consistently. The difference between filters was not statistically significant. Both filters equally contributed to elevation of iliac venous pressure (median, 9.3 and 7.2 mm Hg [n = 9] with the spring filter and RF02 filter, respectively). Caval occlusion occurred in 17% (one of six) and 67% (six of nine) of animals after two clots were trapped in the spring filter and RF02 filter, respectively (P = .06). Other parameters were not influenced by the clot-trapping procedure. CONCLUSION: Although a larger version should be developed and better stability of the filter is needed, the spring filter proved to be an efficient filtering device and had a lower rate of caval occlusion compared with the RF02 filter.

Animals↗
PubMed1999

Placement of a spring filter during interventional treatment of deep venous thrombosis to reduce the risk of pulmonary embolism.

PURPOSE: To assess the efficacy of the Spring filter during interventional treatment of deep venous thrombosis in vivo. MATERIAL AND METHODS: A model of inferior vena cava thrombosis was used. Part I: The thrombus was treated by the pulse-spray technique (PT) (urokinase 250,000 IU; n=7) or a rotatory basket catheter, Thrombolizer (MT) (activated with compressed air at 7 atm; n=5). Part II: Following placement of a Spring filter, the animal underwent PT (n=5) or MT (n=5). Based on the results of part I, the treatment protocol was modified (PT, urokinase 500,000 IU; MT, compressed air at 8 atm). Embolus volumes trapped by the filter and found in the lungs were calculated and the filtering efficacy quantified. RESULTS: Part I: Pulmonary emboli (1 to 4 mm in diameter) were observed in 3 animals in the PT group and 1 animal in the MT group, respectively. Median reduction in thrombus volume was 21% and 4% by PT and MT, respectively. Part II: In the PT group, 58% and 100% of the total embolus load was trapped in 2 animals, while the filter failed to trap emboli (1 to 1.5 mm in diameter) in 1 animal. In the remaining 2 animals, no embolus was found trapped by the filter or in the lungs. In the MT group, 55 97% (median 83%) of the embolus load was trapped. Emboli found in the lungs did not exceed 4 mm in diameter. CONCLUSION: Preceding interventional treatment of venous thrombosis with placement of the Spring filter reduced the embolic burden on the lungs.

Angiography↗
PubMed1999

[Results of muscle flap repair for deep mediastinitis and graft patency after coronary artery bypass grafting].

Between 1978 and 1997, 9 patients developed poststernotomy mediastinitis after coronary artery bypass grafting. Four of these patients (group A) were treated with open drainage and mediastinal irrigation or omental transfer. The other 5 patients (group B) were treated with primary wound closure by the technique of muscle flap mobilization. The purpose of this study was to compare the surgical results and graft patency of both groups. The hospital mortality of group A was 100 per cent. All patients in group B survived for 35 months of the mean postoperative periods without complaints. Postoperative coronary angiography revealed the complete graft patency in group B. We conclude that muscle flap mobilization may be a superior measure for the patient survival and graft patency as the treatment of mediastinitis after coronary artery bypass grafting.

Aged↗
PubMed1998

In vitro function of an adjustable temporary venous spring filter: comparison with the temporary RF02 filter and the permanent Greenfield vena cava filter.

RATIONALE AND OBJECTIVES: The authors compared in vitro function of a temporary venous spring filter with that of a temporary RF02 filter and a permanent Greenfield filter. MATERIALS AND METHODS: All three types of filters were placed in thin polyethylene tubes (diameters, 10.0-18.0 mm). Physiologic saline was substituted for flowing blood, and blood clots of three sizes (6 x 10 mm, 6 x 20 mm, 9 x 20 mm) were funneled to the filters. Clot-trapping ability of each filter and elevation of intraluminal pressure after clot trapping were assessed for each tube size. RESULTS: No statistically significant elevation in intraluminal pressure was detected immediately after placement of any filter. The clot-trapping ability of the spring filter and of Greenfield filter were slightly lower than that of the RF02 filter, but the differences were not statistically significant. After filters had trapped large clots, a high pressure gradient was detected in the 10.0-mm tube for all filters. The spring filter was associated with a higher pressure than the other filters in the 12.0-mm tube (P < .05). CONCLUSION: In vitro function of the spring filter was satisfactory in comparison with that of the RF02 filter and the Greenfield filter. For efficient filtering in the inferior vena cava, development of a larger version of the filter may be necessary.

Equipment Design↗
PubMed1997

Arteriovenous malformation of the gallbladder.

Review of the literature shows no reports of vascular malformation of the gallbladder. Herein we report an unusual case of arteriovenous malformation of the gallbladder in a patient with hepatocellular carcinoma. The gallbladder lesion was found incidentally during abdominal angiography for the carcinoma. The angiographic features were specific, comprising dilated and tortuous feeding cystic arteries, a racemose vascular network, and early-filling cystic veins.

Adult↗
PubMed1997

Adjustable temporary venous spring filter: in vitro assessment.

RATIONALE AND OBJECTIVES: The authors performed an in vitro study to evaluate a temporary venous spring filter that can extend vessels of a wide range of diameters to a slit-shaped canal. MATERIALS AND METHODS: Filters were placed in thin polyethylene tubes or in porcine inferior vena cava specimens (diameter, 10.0-16.0 mm). Physiologic saline was substituted for blood flow, and blood clots of three sizes (6 x 10, 6 x 20, and 9 x 20 mm) were funneled to the filter. Clot-trapping ability was assessed by the degree of luminal extension. RESULTS: When the luminal extension was increased from 2.6r to 2.8r (where r is the original radius of the vein models), clot-trapping ability increased significantly (61.1%-87.5% in polyethylene tubes and 15.8%-77.5% in venous specimens, P < .001). When the luminal extension was increased to 3.0r, more than 90% of the clots were trapped in all tubes. After trapping the small, medium, and large clots, mean intraluminal pressure elevation was 1.0, 1.0, and 17.0 cm of saline, respectively. CONCLUSION: Despite its simple design, the spring filter proved to be an efficient filtering device.

Animals↗
PubMed1997

[Diagnostic imaging of "body packers"].

Drug smuggling by intra-abdominal concealment, so called "body packing," has recently increased, even in Japan. Because of fatal drug intoxication and other adverse side effects, it is important to make a radiological diagnosis of body packers as soon as possible. A retrospective analysis of the images of plain abdominal radiography, computed tomography (CT) and ultrasound (US) was performed in twenty-three body packers to evaluate the imaging characteristics of three drugs (cannabis, cocaine and heroin). Cannabis (16 patients) and cocaine (5 patients) packages were demonstrated as well-demarcated rectangular-shaped high-density shadows surrounded by gas halo ("double condom sign") in abdominal plain radiographs and CT. Heroin packages (2 patients) were demonstrated as obscure shadows and were difficult to identify on plain radiographs, because they resembled stool masses. US was performed in one cannabis patient because of the refusal of radiological examination, and packages were demonstrated as round echogenic structures with dorsal echo extinctions. In conclusion, abdominal plain radiography, CT and US represent valuable diagnostic modalities in the assessment of body packers.

Abdomen↗
PubMed1997

[Assessment of cerebral circulation using echo planar imaging--basic analysis in quantitating the mean transit time, cerebral blood flow, and cerebral blood volume].

The mean transit time (MTT), cerebral blood flow (CBF) and cerebral blood volume (CBV) using echo planar imaging (EPI) in 22 aged volunteers were measured based on moment analysis and gamma variate method. The first peak of signal intensity curve (p delta R2.) and the area under the curve after the first peak (AUC) were calculated according to the height over area method, as a convenient quantification. Then, MTT, CBF, and CBV were compared with AUC/p delta R2, p delta R2, and AUC, respectively. There was a good correlation between each other parameter (r = 0.67 - 0.92, every p < 0.001). The slow upward slope and the low peak height, however, caused a larger error between each other parameter.

Blood Flow Velocity↗
PubMed1996

The X-ray contrast medium iodixanol detects increased colonic permeability equally well as 51Cr-labeled ethylenediaminetetraacetic acid in experimental colitis of rats.

BACKGROUND: Non-ionic, water-soluble radiographic contrast media have been suggested as intestinal permeability probes. We studied the permeability of the isosmolar contrast medium iodixanol and 51Cr-labeled ethylenediaminetetraacetic acid (EDTA) from the non-perforated colon after induction of colonic inflammation. METHODS: Colonic inflammation and ulcerations were induced by luminal colonic instillation of trinitrobenzenesulfonic acid, dissolved in 40% ethanol. Controls received saline. Fourteen days later iodixanol, 320 mg I/ml, and 51Cr-EDTA were given as an enema. Urine was collected for the subsequent 6 h and subjected to high-performance liquid chromatography and gamma activity counting. RESULTS: Urinary recovery of iodixanol and 51Cr-EDTA increased gradually with severity of the colonic inflammation. The correlation between iodixanol and 51Cr-EDTA recovery was strong (corr.coeff = 0.97). CONCLUSIONS: Iodixanol shows as good properties as 51Cr-EDTA when used as intestinal permeability probe in the inflamed and ulcerated rat colon. Use of the radiopaque properties of iodixanol enable intestinal probe exposure registration by film or fluoroscopy.

Animals↗
PubMed1996

[3D contrast MR angiography of lower extremity : additional imaging with subtraction].

Immediately after pelvic contrast MRA, subtraction MRA with additional administration of contrast agent was performed for evaluation of the femoropopliteal artery. Mask images were taken with three- dimensional spoiled GRASS (24/6.9/40 degrees), followed by contrast images with 7.5 - 10 ml of Gd-DTPA. The subtracted images provided excellent depiction of the arteries without the disruption of overlapping from the venous system or surrounding tissues. Seven lesions of arterial occlusion or stenosis were pointed out by subtraction MRA in the nine lesions confirmed with IADSA. Subtraction MRA is feasible for long segment imaging of the lower extremities with Gd-DTPA.

Adult↗
PubMed1995

[MR angiography of the venous system of lower extremities with gadolinium-enhanced fast spoiled GRASS].

MR angiography (MRA) of the venous system of the lower extremities was carried out in 10 patients with varicose veins using the Gd-DTPA-enhanced Fast Spoiled GRASS (FSPGR) method. The quality of imaging of the popliteal vein (n = 20), calf deep vein (n = 20), varicose vein (n = 12), and femoral vein (n = 6) were assessed in terms of four categories: excellent, good, marginally adequate and nondiagnostic. Nineteen popliteal veins, seventeen calf deep veins, and nine varicose veins were judged as excellent or good. All femoral veins were evaluated as excellent. Enhanced FSPGR was useful for the preoperative evaluation of patients with varicose veins.

Femoral Vein↗