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Biomedical subjects

T Ichikawa

Publications and source records attributed to T Ichikawa.

At least 757 records · Page 42Linked to original sources
PubMedDate not supplied

Diffusion-weighted MR imaging with single-shot echo-planar imaging in the upper abdomen: preliminary clinical experience in 61 patients.

BACKGROUND: To determine the potential ability of diffusion-weighted magnetic resonance (MR) imaging with single-shot echo-planar imaging (DW imaging) in the upper abdomen by apparent diffusion coefficient (ADC) and signal:intensity ratio (SIR) measurements. METHODS: DW imaging was performed in 61 clinical patients. ADCs in the liver, pancreas, spleen, kidney, and different pathological conditions were calculated. Spleen-to-liver SIR and segmental intensity difference of the liver (SID) were also calculated. RESULTS: The mean ADCs (mm(2)/s) were 2.28 x 10(-3) +/- 0.07 in the liver, 1.44 x 10(-3) +/- 0.05 in the spleen, 1.94 x 10(-3) +/- 0.19 in the pancreas, and 5.76 x 10(-3) +/- 0.06 in the kidney. The mean ADC of cirrhotic liver was 1.96 x 10(-3) +/- 0.62, which was lower than that of normal liver. Other pathologic conditions also showed ADCs different from those of normal tissues. All DW images showed significantly higher spleen-to-liver SIRs and SIDs than did T2-weighted images (p < 0.05). CONCLUSION: The mean ADCs obtained with DW imaging were different in each upper abdominal organ and with each pathologic condition. DW images showed better soft tissue contrast than did T2-weighted images with regard to SIR and CNR in depicting and characterizing upper abdominal disorders.

Adult↗
PubMedDate not supplied

Detection of hepatocellular carcinoma and its metastases with various pulse sequences using superparamagnetic iron oxide (SHU-555-A).

BACKGROUND: To identify the most useful combinations of various pre- and postcontrast magnetic resonance (MR) image sequences in detecting hepatocellular carcinoma (HCC) and its intrahepatic metastases before and after injection of SHU-555-A. METHODS: Thirty-eight lesions in 16 patients were evaluated before and after administration of SHU-555-A by using fast spin echo (FSE), gradient echo (GRE), and echo planar (EP) imaging sequences using a 1.5-Tesla superconducting MR system. The signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) of the lesions, signal-to-noise ratios, and other parameters were calculated. RESULTS: Tumors were better detected after injection of SHU-555-A on all pulse sequences except on out-of-phase T1-weighted (T1W)-GRE sequences. Tumor detectability was higher for precontrast EP imaging and T2*-weighted (T2*W)-GRE sequences, whereas detectability at postcontrast was higher for T2*W-GRE, proton-density-weighted-FSE, and in-phase T1W-GRE sequences. The SIR and CNR at precontrast were highest for EP imaging, and those at postcontrast were highest for T2*W-GRE. CONCLUSION: SHU-555-A will increase the detectability of HCC and its liver metastases. T1W- and T2*W-GRE sequences would be the sequences of choice.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Isolation and amino acid sequence of urotensin I, a vasoactive and ACTH-releasing neuropeptide, from the carp (Cyprinus carpio) urophysis.

Urotensin I (UI), a 41-residue mammalian hypotensive and fish or mammalian corticotropin-releasing peptide, isolated from 0.1 N HCI extracts of urophyses of the carp (Cyprinus carpio) was purified and the amino acid sequence was determined to be: H-Asn-Asp-Asp-Pro-Pro-Ile-Ser-Ile-Asp-Leu-Thr-Phe-His-Leu-Leu- Arg-Asn-Met-Ile-Glu-Met-Ala-Arg-Asn-Glu-Asn-Gln-Arg-Glu-Gln-Ala-Gly-Leu-Asn-Arg-Lys-Tyr-Leu-Asp-Glu-Val-NH2. When the extraction procedure included heating at 100 degrees C for 15 min, UI was cleaved at a highly acid labile Asp-Pro bond to give the fully active UI (4-41). Urotensin I shows close structural and biological homology with the recently isolated ovine hypothalamic corticotropin-releasing factor (CRF) and the frog skin peptide sauvagine and thus may be considered an evolutionary prototype of unique mammalian-hypotensive and vertebrate corticotropin-releasing factors.

Amino Acid Sequence↗
PubMedDate not supplied

Ca2+/calmodulin-dependent protein kinase II in the rat cerebellum: an immunohistochemical study with monoclonal antibodies specific to either alpha or beta subunit.

Monoclonal antibodies specific to either alpha or beta subunit of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) of the rat brain were produced and the distribution of each subunit in the rat cerebellum was examined immunohistochemically. Each antibody detected solely the corresponding subunit in immunoblot analysis of crude homogenates of the rat forebrain and cerebellum, and purified CaM kinase II from the rat forebrain. Immunoreactivity for alpha subunit was present selectively in Purkinje cells: perikarya, dendrites with their spines, axons and their terminal-like structures in the cerebellar cortex, cerebellar nuclei and lateral vestibular nucleus. Many of these alpha subunit-immunoreactive axons from the cerebellum were traced only through the inferior cerebellar peduncle. beta Subunit was detected in perikarya and dendrites of a limited number of Purkinje cells, many granule cells and neurons in the cerebellar nuclei. Thus, different distributions of alpha and beta subunits of CaM kinase II in the cerebellum were demonstrated.

Animals↗
PubMedDate not supplied

Extraadrenal pheochromocytoma: dynamic demonstration at 0.5 tesla.

We report a case of extraadrenal pheochromocytoma of Zuckerkandl imaged by dynamic magnetic resonance imaging (dynamic MRI) with a 0.5 tesla (T) machine. The dynamic MRI proved useful in disclosing the tumor clearly because of strong enhancement in its early phase. This case has the advantages of dynamic computed tomography (dynamic CT) as well as of T2-weighted spin-echo (SE) MR images.

Adult↗
PubMedDate not supplied

Retroperitoneal ganglioneuroma extending across the midline: MR features.

A rare adult case of retroperitoneal ganglioneuroma in which magnetic resonance imaging (MRI) clearly demonstrated unusual extension of the tumor across the midline is reported. Dynamic MR imaging was very useful to distinguish benign ganglioneuroma from other retroperitoneal tumors, especially neuroblastoma and pheochromocytoma.

Adult↗
PubMedDate not supplied

Diffuse arteriovenous malformation involving jejunum and total colon with mesenteric varices. Case report.

Diffuse intestinal arteriovenous malformation (AVM) is very rare. We describe a case of diffuse AVM involving the jejunum and the total colon in an adult. In addition, mesenteric varices without portal hypertension is demonstrated on angiography of the superior mesenteric artery. The high flow through the AVMs may be a major component in the etiology of the mesenteric varices in our case.

Aged↗
PubMedDate not supplied

Rupture of a hepatic metastasis from renal cell carcinoma.

We describe a rare case of spontaneous rupture of a hepatic metastasis from renal cell carcinoma that was treated successfully by hepatic arterial embolization. A 65-year-old woman, who had been undergoing immunotherapy for inoperably disseminated renal carcinoma and lung metastases, presented with severe abdominal pain in a state of hypovolemic shock. Computed tomography revealed a highly attenuated mass lesion in the right lobe of the liver and massive intraperitoneal hemorrhage. Subsequent hepatic angiography showed extravasation from the feeding right hepatic artery. Transcatheter embolization of the right hepatic artery was subsequently performed, and the patient made an uneventful recovery. Although hepatic rupture due to metastatic cancer is extremely rare, transcatheter arterial embolization (TAE) is an appropriate and useful treatment for massive hemorrhage caused by spontaneous rupture of liver metastasis.

Aged↗
PubMedDate not supplied

Transcatheter arterial embolization for postpartum massive hemorrhage: a case report.

A 29-year-old woman suffered uncontrollable massive hemorrhage from a deep vaginal laceration following spontaneous vaginal delivery. Pelvic angiography revealed extravasation from a branch of the right pudendal artery. Transcatheter arterial embolization was successfully performed and quickly achieved hemostasis. When postpartum hemorrhage cannot be controlled with conservative treatment, transcatheter arterial embolization should be considered in order to avoid major surgery in an unstable patient and to maintain reproductive potential.

Adult↗
PubMedDate not supplied

Identification and role of adenylyl cyclase in auxin signalling in higher plants.

Cyclic AMP is an important signalling molecule in prokaryotes and eukaryotes, but its significance in higher plants has been generally doubted because they have low adenylyl cyclase activity and barely detectable amounts of cAMP. Here we used activation T-DNA tagging to create tobacco cell lines that can proliferate in the absence of the phytohormone auxin in the culture media. The sequence tagged in one line, axi 141, was used to isolate a complementary DNA encoding adenylyl cyclase, the first from a higher plant. Sequence analysis reveals that the tobacco adenylyl cyclase is probably soluble, contains characteristic leucine-rich repeats, and bears similarity with adenylyl cyclase from the yeast Schizosaccharomyces pombe. Expression of the cDNA in Escherichia coli results in an increase in endogenous cAMP levels, and in yeast its expression functionally complements the cry1 mutation. Tobacco protoplasts treated with cAMP, or the adenylyl cyclase activator forskolin, no longer require auxin to divide. This finding, together with the observation that the adenylyl cyclase inhibitor dideoxyadenosine inhibits cell proliferation in the presence of auxin, suggests that cAMP is involved in auxin-triggered cell division in higher plants.

Adenylyl Cyclases↗
PubMedDate not supplied

MRI of soft-tissue lesions: opposed-phase T2*-weighted gradient-echo images.

We evaluated the ability of opposed-phase T2*-weighted gradient-echo (T2*GE) MRI to demarcate soft tissue lesions. The series contained 37 cases, including 18 benign tumors, 8 malignant tumors, and 11 miscellaneous nonneoplastic soft-tissue lesions. Images were obtained on a 0.5 T magnet with T2*GE imaging (TR/TE 300/22 ms, 20 degrees). Results were compared with those of T1-weighted SE images (500/20-40) and T2-weighted SE (T2SE) images (2,000/80). The T2*GE images were similar to T2SE images with respect to the signal behavior and internal architecture of the masses in many cases. In some instances, they were better than T2SE images in delineating the lesions and adjacent fat tissue, in delineating the lesions and adjacent small vessels, and in depicting special features such as hemosiderin deposits. They were inferior to T2SE images in delineating the lesions and adjacent muscles. Because of reduced lesion-muscle delineation, T2*GE images can not be substituted for T2SE images in the evaluation of soft-tissue lesions, but are useful as an adjunct in some cases.

Abscess↗
PubMedDate not supplied

Breath-held MR cholangiopancreatography with half-averaged single shot hybrid rapid acquisition with relaxation enhancement sequence: comparison of fast GRE and SE sequences.

PURPOSE: Our goal was to determine whether half-averaged single shot hybrid rapid acquisition with relaxation enhancement (single shot hybrid RARE) sequence can improve image quality, duct conspicuity, signal intensity ratio (SIR), and contrast-to-noise ratio (CNR) of MR cholangiopancreatography (MRCP) by comparing it with two other MRCP sequences: fast SE (FSE) and contrast-enhanced Fourier-acquired steady-state technique (CE-FAST). METHOD: MRCP with three sequences was obtained in 46 people (10 volunteers, 36 patients with pancreatobiliary disease). Overall image quality and duct conspicuity were graded. SIR and CNR were also measured. RESULTS: Overall image quality was graded excellent or good in all 46 patients (100%) with single shot hybrid RARE, in 38 of 46 (83%) with FSE, and in 5 of 46 (11%) with CE-FAST. Duct conspicuity was the best in single shot hybrid RARE statistically. SIR was the highest in FSE, while CNR was highest statistically in single shot hybrid RARE of three sequences. CONCLUSION: Single shot hybrid RARE can provide consistently higher quality MRCP than FSE and CE-FAST because sequential images by single shot hybrid RARE minimize respiratory, bowel, and cardiac motion artifacts.

Adolescent↗
PubMedDate not supplied

A case of abnormal pancreaticobiliary junction evidenced by 3D drip infusion cholangiography CT.

We report a case of abnormal pancreaticobiliary junction (APBJ), in which three-dimensional (3D) drip infusion cholangiography (DIC) computed tomography (CT) was useful to make the diagnosis. The 3D DIC CT clearly demonstrated reflux of the contrast material into the main pancreatic duct as well as a long common channel, dilated biliary tree, and duodenal lumen. Thereby, we could diagnose APBJ. We believe that 3D DIC CT is a valuable method in the evaluation of patients with suspected APBJ.

Aged↗
PubMedDate not supplied

Differentiation of ejaculates showing reactive oxygen species production by spermatozoa or leukocytes.

Differences between subgroups and correlations between reactive oxygen species (ROS), sperm motility, concentration of leukocytes and viability in semen samples from 143 men were investigated. Patients with azoospermia or leukocytospermia were excluded from the study. Spermatozoa were separated by means of glass wool filtration. Reactive oxygen species were determined by means of luminol chemiluminescence before and after sperm separation; thereafter, normozoospermic and oligozoospermic patients were divided into three subgroups using the mean of all patients investigated (17462 count 10(-7) viable spermatozoa) as cut-off value as follows: G1--high reactive oxygen species production in native semen and after glass wool filtration; G2--high production of reactive oxygen species only in native semen; G3--low levels of reactive oxygen species before and after glass wool filtration. In general, reactive oxygen species were significantly higher in oligozoospermic samples than in normozoospermic samples. In men with normal sperm count, ROS production correlated significantly with the number of leukocytes in the ejaculate before glass wool filtration, but not thereafter. Glass wool filtration is useful to distinguish between sperm samples in which reactive oxygen species are generated by leukocytes and those in which reactive oxygen species are excessively generated by the spermatozoa themselves.

Humans↗
PubMedDate not supplied

Low-dose doxapram therapy in premature infants and its CSF and serum concentrations.

The efficacy of low-dose doxapram therapy (0.2 mg/kg/h) in combination with methylxanthines was evaluated in 20 premature infants with idiopathic apnea unresponsive to methylxanthines alone, and in 13 premature infants with secondary apnea. The serum concentrations of doxapram and, in some infants, the simultaneous cerebrospinal fluid and serum concentrations were measured, and the correlation between cerebrospinal fluid and serum concentrations in the postnatal period was determined. The following results were obtained: 1) In idiopathic apnea of prematurity, low-dose doxapram therapy was as effective as a dose of 1.0-2.5 mg/kg/h and the side effects were few, mild, and reversible. 2) In premature infants over seven days of age, serum concentrations of doxapram were almost stable but were significantly lower than in infants within the first six days of life. 3) The ratio of the cerebrospinal fluid to serum doxapram concentration was 0.48 +/- 0.13 (mean +/- SD). There was a good correlation between cerebrospinal fluid and serum concentrations (r = 0.933, p less than 0.001). The initial doxapram dose can be set as low as 0.2 mg/kg/h in very young premature infants with idiopathic apnea of prematurity unresponsive to methylxanthines.

Aminophylline↗
PubMedDate not supplied

Hepatic adenomas: imaging and pathologic findings.

Hepatocellular adenoma is a rare benign lesion that is most often seen in young women with a history of oral contraceptive use. It is typically solitary, although multiple lesions have been reported, particularly in patients with glycogen storage disease and liver adenomatosis. Because of the risk of hemorrhage and malignant transformation, hepatocellular adenomas must be identified and treated promptly. At pathologic analysis, hepatocellular adenoma is usually a well-circumscribed, nonlobulated lesion, and at gross examination, resected adenomas frequently demonstrate areas of hemorrhage and infarction. Most adenomas are not specifically diagnosed at ultrasonography (US) and are usually further evaluated with computed tomography (CT) or other imaging modalities. Color Doppler US may help differentiate hepatocellular adenoma from focal nodular hyperplasia. Multiphasic helical CT allows more accurate detection and characterization of focal hepatic lesions. Hepatocellular adenomas are typically bright on T1-weighted magnetic resonance images and predominantly hyperintense relative to liver on T2-weighted images. The prognosis of hepatic adenoma is not well established. Criteria that guide treatment include the number and size of the lesions, the presence of symptoms, and the surgical risk incurred by the patient. Understanding the imaging appearance of hepatocellular adenoma can help avoid misdiagnosis and facilitate prompt, effective treatment.

Adenoma, Liver Cell↗