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Biomedical subjects

N Isoda

Publications and source records attributed to N Isoda.

At least 19 recordsLinked to original sources
PubMed2006

Pathogenicity of a highly pathogenic avian influenza virus, A/chicken/Yamaguchi/7/04 (H5N1) in different species of birds and mammals.

Outbreaks of highly pathogenic avian influenza (HPAI) have been occurring in domestic poultry in Asia since 1996. In the beginning of 2004, HPAI outbreaks were caused by H5N1 virus in two farms and a group of pet chickens in different areas of Japan. In the present study, the pathogenicity of A/chicken/Yamaguchi/7/04 (H5N1), which had been isolated from a dead chicken during the first outbreak in Japan, was assessed in chickens, quails, budgerigars, ducklings, mice, and miniature pigs by experimental infection. The virus was highly pathogenic to all the birds tested. Mice were susceptible to infection with a low mortality rate and miniature pigs were resistant to infection with the virus.

Animals↗
PubMed2005

Pathogenicity of H5 influenza viruses for ducks.

Four H5N1 highly pathogenic avian influenza (HPAI) viruses and an avirulent reassortant H5N1 virus were tested for their pathogenicity in domestic ducks. A/chicken/Yamaguchi/7/04 (H5N1) (Ck/Yamaguchi/04) isolated from a dead bird during the HPAI outbreak in Japan and A/duck/Yokohama/aq-10/03 (H5N1) (Dk/Yokohama/03) isolated from duck meat at a quarantine inspection for importation from China replicated in multiple organs including the brain of ducks. The ducks infected with Ck/Yamaguchi/04 did not show any clinical signs, while those infected with Dk/Yokohama/03 showed neurological signs. The ducks infected either with A/Hong Kong/483/97 (H5N1) or A/tern/South Africa/61 (H5N3), or with an avirulent H5N1 reassortant, did not show any clinical signs. Virus-specific antibodies were detected in the sera of the ducks infected with each of the five strains tested, indicating that all of the viral strains infected and replicated in the birds. Dk/Yokohama/03 grew in multiple organs more rapidly than did Ck/Yamaguchi/04. Considerable titers of virus were detected in the brain of the ducks infected with Dk/Yokohama/03 and these birds showed neurological signs. The present results demonstrate that the pathogenicity of influenza viruses for ducks does not correlate with that for chickens and that replication of the virus in the brain is critical for ducks to show neurological signs.

Animals↗
PubMed2005

Pericryptal fibroblast sheath in intestinal metaplasia and gastric carcinoma.

BACKGROUND AND AIMS: In the progression of chronic gastritis, gastric mucosal cells deviate from the normal pathway of gastric differentiation to an intestinal phenotype which is closely related to gastric carcinoma. However, to date, it has not been elucidated whether the intestinal metaplasia is merely a change in the epithelium or whether the underlying mesenchyme also changes from gastric type to intestinal type. We have investigated the relationship between intestinal metaplasia and the pericryptal fibroblast sheath (PCFS) in the mesenchyme. In addition, we also examined PCFS in gastric carcinoma. METHODS: We determined the existence of PCFS in the intestinal metaplastic mucosa and carcinoma of both human and Cdx2 transgenic mouse stomach. PCFS was determined using the antibody against alpha-smooth muscle actin and electron microscopic observations. RESULTS: PCFS formed an almost complete layer around the small and large intestinal crypts while it did not exist around the normal gastric glands in both mice and humans. PCFS was seen around the glands of intestinal metaplastic mucosa in both Cdx2 transgenic mouse and human stomachs. However, PCFS was virtually absent in the intestinal-type gastric adenocarcinoma area. CONCLUSION: We successfully demonstrated that the epithelium as well as the mesenchyme changed from the gastric type to the intestinal type in intestinal metaplasia and that PCFS disappeared in intestinal-type gastric carcinoma.

Actins↗
PubMed2003

Easy and accurate targeting of deep-seated hepatic tumors under laparoscopy with a forward-viewing convex-array transducer.

BACKGROUND: It is technically difficult to puncture deep-seated hepatic tumors by conventional laparoscopic ultrasonography with a linear-array probe. We have developed a laparoscopic ultrasonography system with a convex-array probe. METHODS: The laparoscopic system used had a fixed forward-viewing convex-array transducer, and a guide groove for puncture was added to the back of the unit. These characteristics enabled us to continuously monitor the position of the needle tip on the ultrasonographic image immediately after puncturing on the liver surface. We attempted tumor puncture in 11 patients with hepatocellular carcinoma under a new probe guidance. RESULTS: The mean puncturing distance up to the tumors was 38.7 mm. All punctures were successful on the first pass and the tumors were treated with radiofrequency ablation. CONCLUSION: Using this new equipment, puncturing hepatic tumors for treatment is relatively easy, irrespective of the position of the tumor.

Adult↗
PubMed2001

Intraductal ultrasonography for hepatocellular carcinoma with tumor thrombi in the bile duct: comparison with polypoid cholangiocarcinoma.

BACKGROUND AND AIM: Tumor thrombi in the bile duct caused by hepatocellular carcinoma (HCC), and cholangiocarcinoma show polypoid lesions on cholangiographic findings. This study prospectively compared the images of intraductal ultrasonography between HCC and polypoid cholangiocarcinoma. METHODS: In five patients with tumor thrombi in the bile duct caused by HCC, a 2.0 mm diameter ultrasonic probe with a frequency of 20 MHz was inserted into the bile duct via the transpapillary route (n = 4) or the transhepatic route (n = 1). The images were compared to that of 65 patients with cholangiocarcinoma. RESULTS: In all patients with HCC, intraductal ultrasonography showed a 'polypoid tumor with a narrow base'. In 16 of 65 patients with cholangiocarcinoma, it showed a 'polypoid tumor with a narrow base'. When intraductal ultrasonography showed a 'polypoid tumor with a narrow base', the findings of a positive 'nodule within a nodule' (40 vs 0%; P < 0.05), and the absence of a 'papillary-surface pattern' (80 vs 13%; P < 0.05) were more highly associated with tumor thrombi caused by HCC than to polypoid-type cholangiocarcinoma. CONCLUSIONS: Intraductal ultrasonography was useful to distinguish between tumor thrombi caused by HCC and polypoid-type cholangiocarcinoma.

Aged↗
PubMed2001

Laparoscopic adhesiolysis for recurrent small bowel obstruction: long-term follow-up.

BACKGROUND: Recurrent small bowel obstruction caused by postoperative adhesions has traditionally been treated by conventional laparotomy, but laparoscopic management of acute small bowel obstruction has been reported. The aim of this study was to assess the long-term efficacy and clinical outcome of laparoscopic adhesiolysis for recurrent small bowel obstruction. METHODS: After conservative treatment, elective laparoscopic treatment was attempted in 17 patients hospitalized for recurrent small bowel obstruction after abdominal or pelvic surgery. RESULTS: Postoperative adhesions were identified laparoscopically in all patients. Laparoscopic treatment was possible in 14 patients (82.4%). Conversion to laparotomy was required for 3 patients (17.6%) because of intestinal perforation (n = 1) or a convoluted mass of adherent bowel (n = 2). Long-term follow-up was possible in 16 patients. Two recurrences of small bowel obstructions were noted over a mean follow-up period of 61.7 months. CONCLUSIONS: Laparoscopic adhesiolysis is a safe and effective treatment for recurrent small bowel obstruction. Conversion to laparotomy should be considered in patients with dense adhesions.

Feasibility Studies↗
PubMed2000

Microwave coagulation therapy: ex vivo comparison of MR imaging and histopathology.

We compared the findings of magnetic resonance (MR) images and pathological examination to determine whether or not MR images reflect pathological changes following microwave coagulation therapy (MCT) on liver tissue. We used microwave (generating frequency 2450 Mhz, wave length 12 cm, output 50 W, 60 second duration) to irradiate six canine livers under general anesthesia. After the animals were sacrificed, the livers were resected. The irradiated regions were cut with margins and divided into two pieces, one for MR study, and the other for pathological examination. The findings were compared. From the center to the marginal layer, the irradiated region presented 4/3 laminal patterns on T1/T2-weighted images: low/high, high/low, very high/high, and iso-low/high intensity. On gradient-echo imaging, the irradiated regions presented no decreasing signals using several echo time lengths. With hematoxylin and eosin stain, MR laminar patterns reflected the histopathological changes, as follows: a tissue loss area surrounding the inserted needle, low/high; decreased sinusoidal width with/without necrotic tissue, high/low; sinusoidal width dilation at the periphery, very high/high; and fatty degenerated tissue surrounding the irradiated area at the boundary of the normal hepatocytes, iso-low/high. The MR signal intensity, which reflected the histopathological changes, presented tissue characterization after MCT, and the macromolecular hydration effect influenced the high intensity on T1-weighted images.

Animals↗
PubMed2000

Intraductal ultrasonographic assessment of coagulation depth during endoscopic microwave coagulation therapy in a canine model.

In order to examine the feasibility of endoscopic microwave coagulation therapy (MCT) for the treatment of common bile duct cancer in humans, we investigated the safety and effectiveness of endoscopic MCT with the assistance of intraductal ultrasonography (IDUS). We performed MCT in the canine small intestine as a model because of its similarity in size to the obstructed human common bile duct. Multiple coagulation lesions were made in anesthetized dogs, with the endoscope inserted through a jejunostomy. Under condition "A", the tip of the MCT probe was kept in a fixed position in contact with the mucosa of the intestine, and coagulation was performed with an output of 30 or 50 W for 30 or 10 s, respectively. Under condition "B", the tip of the MCT probe was moved along the intestinal mucosa, and coagulation was performed with an output of 50, 40, or 30 W, all for 10 s. After coagulation, a thin-caliber ultrasonic probe was inserted endoscopically for observation of the effects of coagulation. Each coagulation under condition "A" resulted in degeneration of all layers of the intestine. Coagulation under condition "B" resulted in more localized degeneration, extending from the mucosal layer to the proper muscle layer. By comparison with histologic observations, the accuracy of IDUS in assessing depth of degeneration was 87.5%. Endoscopic microwave coagulation was considered safe and effective, and IDUS was able to accurately assess the effects of microwave coagulation.

Animals↗
PubMed1999

Laparoscopic cholecystectomy in gallstone patients with acute cholecystitis.

It remains controversial whether patients with gallstones with acute cholecystitis should be operated on early, or whether surgery should be delayed until the acute phase subsides. To help resolve this question, we retrospectively studied 109 patients with acute cholecystitis, 56 of whom underwent laparoscopic cholecystectomy after acute cholecystitis had subsided (delayed group) and 53 of whom underwent early laparoscopic cholecystectomy--within 7 days after admission (early group). On admission, the inflammatory findings in the two groups were very similar; however, at operation, the inflammatory findings were alleviated in the delayed group, while they remained unchanged in the early group. The mean operative time for the two groups was very similar. As for intraoperative complications, there was no conversion to laparotomy in either group, and there were no major complications in either group. The total hospital stay was 37.7 +/- 14.4 days for the delayed group and 12.7 +/- 2.0 days for the early group, showing a highly significant difference (P < 0.001). Early laparoscopic cholecystectomy seems to be better than delayed treatment for patients with gallstones with acute cholecystitis.

Acute Disease↗
PubMed1999

The role of laparoscopic US and laparoscopic US-guided aspiration biopsy in the diagnosis of multicentric hepatocellular carcinoma.

BACKGROUND: Detection of small hepatocellular carcinomas has become possible with improvements in various diagnostic imaging techniques. However, intraoperative US can detect lesions not visualized by any preoperative imaging study in which case it is difficult to determine whether the lesion is a hepatocellular carcinoma. METHODS: Nodular lesions detected by laparoscopic US in 186 patients with hepatocellular carcinoma were examined and we evaluated the diagnostic ability of laparoscopic US to detect multicentric hepatocellular carcinoma. RESULTS: One hundred thirty-four new nodular lesions were detected by laparoscopic US in 64 (34.4%) of 186 patients. Aspiration biopsy under laparoscopic US guidance was performed on the 134 nodules, and 28 nodules in 23 (12.4%) of the 186 patients were histologically diagnosed as hepatocellular carcinoma. Of these 23 patients, 18 had been diagnosed with solitary hepatocellular carcinoma before laparoscopic US. One hundred six of the newly detected lesions were initially diagnosed as noncarcinomatous nodules, but the diagnosis of 10 of these lesions was changed to hepatocellular carcinoma during follow-up that was as long as 96 months. CONCLUSIONS: Laparoscopic US is useful in the initial diagnosis of hepatocellular carcinoma and impacts treatment selection by more accurately defining the presence of multicentric hepatocellular carcinomas.

Biopsy, Needle↗
PubMed1999

Prognosis of small hepatocellular carcinoma after laparoscopic ethanol injection.

BACKGROUND: Most patients with hepatocellular carcinoma have underlying cirrhosis, and this impairment of liver function makes hepatectomy difficult, prompting the use of other modalities such as transcatheter arterial embolization and percutaneous ethanol injection. METHODS: Laparoscopic ethanol injection was performed in 48 previously untreated patients with hepatocellular carcinoma smaller than 2 cm in diameter. Long-term survival was evaluated. RESULTS: In 12 patients, hepatocellular carcinoma was not detected by trans-cutaneous ultrasonography but could be demonstrated by laparoscopic ultrasonography. Laparoscopic ethanol injection did not cause serious complications in any patient. The mean hospital stay after ethanol injection was 8.6 days (4 to 15 days). The cumulative survival rate was 86.7% at 3 years and 60.0% at 5 years. According to the Child-Pugh classification, the cumulative survival rate at 5 years was 87.9% for class A, 65.7% for class B, and 28.6% for class C. CONCLUSIONS: The long-term prognosis for patients with small hepatocellular carcinoma treated solely by laparoscopic ethanol injection is satisfactory but still dependent on underlying liver function.

Adult↗
PubMed1999

A novel method of endoscopic mucosal resection using sodium hyaluronate.

BACKGROUND: Saline-assisted endoscopic mucosal resection is an established therapeutic method. However, it is sometimes difficult to maintain a desired level of tissue elevation after injection of saline. Therefore we decided to use a mucinous substance such as sodium hyaluronate instead of saline. METHODS: Two resected porcine stomachs and five dogs were used for the study. The elevations, made by submucosal injections of sodium hyaluronate, were compared with those produced with normal saline. Sodium hyaluronate-assisted mucosal resections were compared with the saline-assisted resections. RESULTS: Mucosal elevations created by submucosal injections of sodium hyaluronate remained for a longer time with a clearer margin compared to those made by saline injection. Endoscopic mucosal resections were performed safely with the assistance of sodium hyaluronate. CONCLUSIONS: Use of sodium hyaluronate instead of saline for endoscopic mucosal resection could make the procedure easier and more reliable.

Animals↗
PubMed1996

Confirmation of a "safety zone" by intraoperative cholangiography during laparoscopic cholecystectomy.

BACKGROUND: Creating a "safety zone" during laparoscopic cholecystectomy is defined as dissection of the cystic duct as close as possible to the gallbladder. METHODS: In 29 out of 802 cases in which laparoscopic cholecystectomy was difficult to perform due to uncertainty about the orientation of Calot's triangle, intraoperative cholangiography was performed, using a titanium clip as a marker that designated the safety zone. The distance between the clip and the common hepatic duct or the common bile duct could be determined by evaluation of two intraoperative cholangiograms taken in different orientation. RESULTS: If the clip was located in the safety zone, and was distant from the common hepatic duct or common bile duct, the safety of preparation around the clip was ensured. No complication was encountered in these cases with this method. Eventually, no biliary tract injury was experienced, and the overall conversion rate to open cholecystectomy was only 0.4% (3 of 802 consecutive cases). CONCLUSIONS: This method of confirming the safety zone by intraoperative cholangiography is a useful procedure for avoiding inadvertent injury to the biliary tract.

Bile Duct Diseases↗