Biomedical subjects

S Hirota

Publications and source records attributed to S Hirota.

321 records · Page 18Linked to original sources

PubMedDate not supplied

Biliary excretion of trichloroethylene and its metabolites in dogs.

To examine the biliary excretion of trichloroethylene (TRI) and its metabolites, we carried out various experiments with TRI and its metabolites, i.e., chloral hydrate (CH), free-trichloroethanol (F-TCE) and trichloroacetic acid (TCA), using anesthetized dogs. The amount of biliary excretion was significantly increased with the administration of CH and F-TCE, whereas it remained at control levels with the administration of TRI and TCA. The substances excreted into bile were conducted in the form of conjugated-TCE (Conj-TCE) in over 90% of the CH, F-TCE and TRI administration groups. About 95% of these Conj-TCE were conjugated with glucuronic acid. The cumulative excretion ratios of substances and metabolites to dose were 20% for CH and F-TCE, and about 1% for TCA and TRI 2 h after administration.

Animals↗

PubMedDate not supplied

The problem of de novo colorectal carcinoma.

From April 1985 to March 1995, colonoscopy was carried out at our institution in 24,059 patients, 31,800 times in symptomatic and/or asymptomatic average risk persons. 184 submucosal invasive carcinomas were detected. Unlike protruding-type lesion, the depressed-type invades the submucosal layer, even though the size is within 10 mm. The depressed type of invasive carcinoma accounted for 20 lesions, and represented 10.9% (20 of 184) of all the invasive carcinomas. The pit pattern of depressed-type lesions shows a small round pit (type IIIs pit pattern) and that of carcinoma lesions shows the irregular pit and non-structure (type V pit pattern).

Adenoma↗

PubMedDate not supplied

Expression of bone morphogenetic protein-4 mRNA during the process of bone formation in embryogenesis and fracture repair.

Bone morphogenetic protein-4 is a potent inducer of ectopic bone and cartilage formation in vivo. Expression of the bone morphogenetic protein-4 gene has been detected in bone cells during fracture repair but not in normal adult bone cells. To examine whether the gene is expressed by bone cells during embryonic development, in situ hybridization and reverse transcription polymerase chain reaction methods were used to detect murine bone morphogenetic protein-4 specific complementary DNA in murine developmental bone tissues. Bone morphogenetic protein-4 messenger RNA was detected in the cells of various developing bone tissues, but it was not detected in these tissues after birth. Combined with previous reports, our findings indicate that the bone morphogenetic protein-4 gene is expressed during embryogenesis and bone repair and suggest that its product may be a potent bone-forming factor in bone development and fracture repair.

Journal Article↗

PubMedDate not supplied

Transcatheter microembolization with ferropolysaccharide. A new approach to ferromagnetic embolization of tumors: preliminary report.

A new embolic material has been devised to improve the therapeutic effect of ferromagnetic embolization upon tumors. Iron sponge microspheres (diameter 10-30 mu) were suspended in viscous, aqueous polysaccharide solution, dextran 40, and sodium carboxymethyl cellulose (Ferro-polysaccharide, FPS). Transcatheter embolization with FPS was performed under external magnetic control (2,800 gauss) in dog kidneys and VX2 carcinomas of rabbits, causing widespread, intraparenchymal vascular occlusion of target vessels. Neither recanalization nor collateral circulation was found to the infarcted areas, and the embolized tumors had extensive necrosis with resultant tumor regression. No significant untoward reaction or other undesirable embolization was noted serologically or histologically, even after intravenous administration of FPS. Clinical application to two patients, one with a hepatoma and the other with a renal cell carcinoma, resulted in excellent tumor infarction with no significant side effects.

Adenocarcinoma↗

PubMedDate not supplied

Impairment of spatial learning and hippocampal synaptic potentiation in c-kit mutant rats.

The c-kit receptor tyrosine kinase encoded by the white-spotting (W) gene is highly expressed in rat hippocampal CA1-CA4 regions. We found an impaired spatial learning and memory in homozygous c-kit (Ws/Ws) mutant rats that have a 12-base deletion in the tyrosine kinase domain of the c-kit gene and a very low kinase activity. Electrophysiological studies in hippocampal slices revealed that the long-term potentiation (LTP) induced by the tetanic stimulation (100 Hz, 1 sec) in the mossy fiber (MF)-CA3 pathway, but not in the Schaffer collaterals/commissural-CA1 pathway, was significantly reduced in c-kit mutants compared with wild-type (+/+) rats. The paired-pulse facilitation (PPF) was measured before the tetanus and after the establishment of the LTP in each slice. The initial PPF in the MF-CA3 pathway positively correlated with the amplitude of the LTP in the wild-type rats but not in the c-kit mutant rats. Furthermore, they failed to show the normal characteristics observed in the MF-CA3 pathway of +/+ rats; that is, the negative correlation between the initial PPF and the changes in PPF measured after the LTP. These findings suggest an involvement of SCF/c-kit signaling in hippocampal synaptic potentiation and spatial learning and memory.

Animals↗

PubMedDate not supplied

Characterization and tissue distribution of liposomes containing lactose mono-fatty acid derivatives.

In this study we characterized liposomes containing the synthetic glycolipids, lactose mono-fatty acid esters (LFEs), whose structures were the most simple ones compared to the other synthetic glycolipids. Gel filtration chromatography was used to confirm that 78 per cent of lactose monostearic acid ester (LSE) or 85 per cent of lactose monoarachidic acid ester (LAE) existed in the liposomal fraction. The size distribution of liposomes containing LFEs was similar to that of the control liposomes which did not contain LFEs. Liposomes containing LFEs were aggregated by Ricinus communis agglutinin from caster bean (RCA120) while the control liposomes were not, with the agglutinability of the liposomes containing LAE being greater than that of those containing LSE. These findings therefore suggested that the LFEs were incorporated into the liposomal membrane with the galactose residues exposed to the outer aqueous phase. Next, the tissue distribution of liposomes containing LAE at 30 min after intravenous administration was compared to that of the control liposomes in rats. Hepatic uptake was 2-fold higher than that of the control liposomes. These results thus demonstrate that liposomes containing LFEs represent potential drug carriers to the liver.

Animals↗

PubMedDate not supplied

Selective uptake of liposomes containing lactose mono-fatty acid derivatives by hepatic parenchymal cells.

In this study we investigated the hepatic uptake of liposomes containing a novel synthetic glycolipid, lactose mono-arachidic acid amide (LAA). Liposomes containing LAA were aggregated by Ricinus communis agglutinin from caster bean, while the control liposomes were not, and the results suggested that the galactose residues of LAA were exposed to the outer surface of the liposomes. Next, the blood clearance and hepatic uptake of liposomes containing LAA after intravenous administration were compared with those of the control liposomes in rat. Hepatic uptake of liposomes containing LAA was greater than that of the control liposomes, rising significantly with dose. As a result of separation of the parenchymal and non-parenchymal cells, it was shown that the increase in hepatic uptake was mostly accounted for by a greater uptake by parenchymal cells. The inhibitory activity of asialofetuin on the hepatic uptake of liposomes containing LAA suggested that a galactose-specific recognition is involved in this uptake. These results demonstrate that the lactose mono-fatty acid amides (LFAs) are promising novel compounds for the introduction of carbohydrate residues onto the liposomal surface and that liposomes containing LFAs are potential carriers for the selective delivery of drugs to specific cells.

Amides↗

PubMedDate not supplied

Distribution of liposomes containing mannobiose esters of fatty acid in rats.

The biodistribution of liposomes modified by mannobiose residues was studied in rat. The purpose of the modification was to target the liposomes to macrophages. Mannobiose mono arachidic acid esters (MAEs) were synthesized and used to modify the surface of liposomes. It was shown by gel permeation chromatography that the MAE was preferentially incorporated into the membrane of the liposomes. After intravenous administration, mannobiose-modified liposomes were eliminated from the systemic circulation more rapidly than control liposomes without the modification. Whilst the modification did not affect the distribution of liposomes to kidney, lung, or thymus, it increased the distribution to liver and spleen. The uptake in the hepatic parenchymal cell fraction was not influenced by MAE incorporation. Taking into account the fact that endothelial cells do not take up particles whose size is > 100 nm, the increase in the distribution to liver were ascribed to an increase in uptake by Kupffer cells. These results suggest that mannobiose mono fatty acid esters are useful in the targeting of liposomes to Kupffer cells and other macrophages.

Animals↗

PubMedDate not supplied

Application of self-expanding metallic stents to malignant stricture following mechanically stapled esophagojejunostomy: report of two cases.

Several types of self-expanding metallic stents (SEMS) were placed in two patients suffering from severe malignant stricture at the site of a mechanically stapled esophagojejunostomy used for the treatment of recurrent gastric cancer. Following modified Gianturco stent placement with limited success in one of the patients, an additional Ultraflex stent (Boston Scientific Co., Boston, USA) failed to expand satisfactorily at the outlet of the second stent. In the other patient, since the proximal end of an additional covered Ultraflex stent (Boston Scientific Co.) inserted through the first one failed to expand satisfactorily at the level of severe stenosis because of the extreme rigidity caused by the mechanical staples, a spiral Z-stent was inserted to dilate it. The cases reported here raise some problems associated with the treatment of severely malignant stricture accompanied by extreme rigidity following mechanically stapled esophagojejunostomy with SEMS.

Anastomosis, Surgical↗

PubMedDate not supplied

Cystic hamartoma of the renal pelvis: imaging features.

We report a case of a 50-year-old woman with histologically proven cystic hamartoma of the renal pelvis, focusing on the imaging findings and pathologic features. A large multicystic tumor with solid components in the left kidney was enhanced on both contrast-enhanced CT and gadolinium-enhanced MR images. Angiographic images showed irregular tumor vessels with moderate tumor stain.

Diagnosis, Differential↗

PubMedDate not supplied

Topical contrast-enhanced magnetic resonance dacryocystography.

PURPOSE: To evaluate the usefulness of magnetic resonance dacryocystography (MRD) with topical administration of normal saline solution and diluted Gd-DTPA solution for the assessment of lacrimal outflow disorders. MATERIALS AND METHODS: Two T2-weighted sequences and two T1-weighted sequences were evaluated in this study. The 1:100 diluted Gd solution was prepared by diluting Gd-DTPA (Magnevist) with normal saline solution. A phantom study using tube phantoms of various diameters filled with normal saline solution and 1:100 diluted Gd solution was performed. A preliminary study was performed in ten normal volunteers. Eighteen patients with lacrimal outflow disorders underwent clinical MRD, and 14 also underwent conventional dacryocystography (CDG). MRD images were evaluated and compared with clinical symptoms and CDG images. RESULTS: In all sequences, MRD could visualize the full length of 0.7 to 1.7 mm diameter tube phantoms and could show all of the normal lacrimal sacs and nasolacrimal ducts. In the clinical study, MRD findings were compatible with the symptoms in 14 patients but were not compatible with CDG findings in half of the cases. CONCLUSION: Topical contrast-enhanced MRD provided a simple, non-invasive means of obtaining detailed morphological and functional information on the lacrimal drainage apparatus.

Aged↗

PubMedDate not supplied

Chronological observation in early radiation myelopathy of the cervical spinal cord: gadolinium-enhanced MRI findings in two cases.

Gd-enhanced MR images of two patients with clinically and histopathologically diagnosed chronic progressive radiation myelitis (CPRM) were observed chronologically. One of them had had nasopharyngeal cancer and received radiotherapy at a dose of 100 Gy to the C1-2 level of the spinal cord. She developed CPRM 25 months after the termination of radiotherapy. The other had had malignant lymphoma originating from the tonsil and received chemoradiotherapy. The dose delivered to her cervical spinal cord was 40 Gy, and she developed CPRM 30 months later. Gd-enhanced MRI in the early phase revealed a small crescent-shaped nidus with or without a very small central nonenhanced area in both cases. Enhancement was not great. At that time, patients noticed only the inability to perceive pain and temperature or paresthsia in the opposite side. In a few months, MRI revealed a much more strongly enhanced and larger nidus with enlargement of a central nonenhanced area accompanied by long segmental cord enlargement. The patients' neurological symptoms had also progressed, with hemiparesis developing, for example.

Adult↗

PubMedDate not supplied

Radiotherapy of T1 and T2 glottic cancer: analysis of anterior commissure involvement.

From January 1984 to December 1993, 184 patients with previously untreated T1 and T2 (UICC 1987) laryngeal glottic cancer underwent radiotherapy at Hyogo Medical Center for Adults. The prognostic variables analyzed included sex, age, smoking index, T stage, tumor size, tumor type, gross anterior commissure involvement (gross ACI), histological differentiation, administered dose, TDF, overall treatment time, chemotherapy, initial response, and the dose required to achieve CR. Both univariate and multivariate analyses were performed. The T stage, tumor size, and gross ACI were significant variables in univariate analysis, while the tumor type and gross ACI were significant on multivariate analysis. The 5-year recurrence-free survival of patients with gross ACI was significantly worse than that of those without ACI (57.6% vs. 89.9%). Among gross ACI patients, the recurrence-free survival of those treated with 70-72 Gy was superior to that of those receiving 60-62 Gy, suggesting that at least 70 Gy was necessary to control such diseases.

Adult↗

PubMedDate not supplied

Pulmonary arteriovenous fistula: long-term results of percutaneous transcatheter embolization with spring coils.

PURPOSE: The aim of this study was to assess the effectiveness of percutaneous treatment of PAVFs through the results of long-term follow-up. PATIENTS AND METHODS: Transcatheter embolization of PAVFs using spring coils was performed in seven patients (six women and one man) with nine PAVFs, between 1989 and 1995, who were followed up at least one year. The size of the nine PAVFs ranged from 4 mm to 70 mm in diameter (mean 26 mm). Two fistulas were huge, 70 x 45 mm and 60 x 65 mm in diameter. Embolization was performed twice in three patients and once in four patients. In the two patients with huge PAVFs, after anchoring metallic "spiders" into the feeding artery, the largest coils were positioned and entangled with the "spider" followed by the placement of smaller coils to fill in the center of the feeding artery. RESULTS: No severe complications were seen in the short-term follow-up. Arterial oxygen pressure improved in all patients with low oxygen pressure. Five patients with seven fistulas, six of which disappeared on chest X-ray film, are still alive after follow-up ranging from one year and 10 months to seven years and nine months. The two patients with huge fistulas died more than one year after treatment, one of hemoptysis of the contralateral lung and the other of pulmonary fibrosis. CONCLUSION: Complete embolization of a medium-sized feeding artery can cure this anomaly.

Arteriovenous Fistula↗

PubMedDate not supplied

Inferior vena cava filter placement for prevention of pulmonary tumor emboli of renal cancer with renal vein or vena caval tumor thrombus: prophylactic usage prior to transcatheter arterial embolization.

PURPOSE: To prevent pulmonary embolization of necrotic intravenous tumor thrombus after transcatheter embolization of renal cell carcinoma, we placed suprarenal inferior vena cava (IVC) filters. MATERIALS AND METHODS: Suprarenal IVC filters were placed prior to transcatheter arterial embolization (TAE) in four patients, two women and two men, with renal cancer accompanied by renal vein in one and vena caval tumor thrombus in three patients. We used one bird's nest filter for the patient with renal vein tumor thrombus and a titanium Greenfield filter for each of the three patients with vena caval tumor thrombus. TAE was performed with pure ethanol under balloon occlusion of the renal artery. RESULTS: IVC filters were successfully placed at the suprarenal position. The patients tolerated the procedure well and had extensive tumor infarction, including the tumor thrombus, on follow-up computed tomography (CT). No pulmonary infarction or adverse effects were seen during the follow-up period. One patient died from diabetic renal failure, two patients have been alive for 8.5 and 7.5 months respectively, the other one is lost to follow-up. CONCLUSIONS: Suprarenal IVC filter placement prior to TAE for advanced renal cell carcinoma invading the renal vein or the IVC is an effective procedure to prevent pulmonary thromboemboli and may contribute to longer survival.

Aged↗