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Biomedical subjects

N Tanaka

Publications and source records attributed to N Tanaka.

At least 451 records · Page 25Linked to original sources
PubMed1999

Insulin stimulates the growth and tube formation of human microvascular endothelial cells through autocrine vascular endothelial growth factor.

Insulin treatment is known epidemiologically as an independent risk factor for the progression of diabetic retinopathy. However, how insulin exacerbates the retinopathy is not yet fully understood. In this study, we investigate the effects of insulin on the growth and tube formation of microvascular endothelial cells (EC). When human skin microvascular EC were grown under various concentrations of insulin, DNA synthesis as well as tube formation of EC was found to be significantly stimulated. We obtained evidence that it is mainly vascular endothelial growth factor (VEGF) that mediates the angiogenic activity of insulin as follows. (1) Insulin upregulates the level of mRNA coding for secretory forms of VEGF, while the expression of the two VEGF receptor genes, kinase insert domain-containing receptor (kdr) and fms-like tyrosine kinase1 (flt1), was essentially unchanged by exposure to insulin. (2) A monoclonal antibody against human VEGF can completely neutralize both the proliferation and the tube formation of EC induced by insulin. The angiogenic effects of insulin were additive with those of hypoxia, a principal factor that causes angiogenesis. Further, insulin significantly stimulated plasminogen activator inhibitor-1 activity in EC. The results thus suggest that insulin not only elicits angiogenesis through the induction of autocrine VEGF but also is a predisposing factor for thrombogenesis, which may give rise to focal ischemia that could superdrive angiogenesis, thereby leading to the exacerbation of diabetic retinopathy.

Autocrine Communication↗
PubMed1999

The usefulness of conducting investigations on intra-abdominal bacterial contamination in digestive tract operations.

A bacteriological study of 108 cases of gastrointestinal surgery was conducted by analyzing intra-abdominal bacterial contamination (IABC) and postoperative surgical site infections (SSI). We utilized an anaerobic porter to detect intra-abdominal bacterial infection and transport bacteria to the laboratory. The positive IABC rate was 42.9% for gastric cancer surgery, 22.6% for biliary tract surgery, and 85.7% for colorectal cancer surgery. Most cases of SSI were IABC-positive, and isolated bacterial species from the SSI were similar to those from the IABC. In colorectal cancer surgery, a preoperative chemical intestinal preparation and the prophylactic use of antibiotics had a major influence on the sensitivity of bacteria isolated from the SSI. These data suggest that prophylactic antibiotics should be chosen from among those to which bacteria from the IABC are highly sensitive, and that therapeutic antibiotics should be chosen from among those to which bacteria isolated from the SSI are highly sensitive. Finally, the exploration of IABC enables us to predict the incidence of SSI.

Adult↗
PubMed1999

Dermoid cyst of the spleen: report of a case.

A rare splenic dermoid cyst in an 11-year-old girl is reported herein. The patient was referred to us with the chief complaint of acute-onset abdominal pain. The lesion was demonstrated by ultrasonography, computed tomography, and magnetic resonance imaging to be a cystic lesion containing serous fluid. A splenectomy was performed. Both histopathological and immunohistochemical findings demonstrated the cyst to be a dermoid cyst of the spleen. To avoid the risk of infection following splenectomy, polyvalent pneumococcus vaccine was administered. The patient recovered uneventfully. We performed immunohistochemical studies with cytokeratin and electron microscopy to determine the origin of the cyst.

Abdominal Pain↗
PubMed1999

Increase in histidine decarboxylase activity in tissues of mice bearing Colon-26 tumor cells.

The changes in histidine decarboxylase (HDC) activity, histamine and tele-methylhistamine contents were examined in tissues of mice after the inoculation of Colon-26 tumor cells subcutaneously into the lower back. The HDC activity in the spleen of mice increased significantly 14 days after the inoculation of Colon-26 and the increase in HDC activity continued for up to 28 days. However, the histamine content in the spleen of tumor-bearing mice was not changed significantly during the observation period. In the following experiments, two subclones of the Colon-26 cell line, cachexia-inducing clone-20 and non cachexia-inducing clone-5, were used and the induction of HDC activity in mice was examined in four tissues, spleen, lung, liver and kidney. Both clone-20 and clone-5 induced the increase in HDC activity to the same extent in the spleen and lung, but not in the liver and kidney. As observed using the Colon-26 original cell line, the histamine contents in the four tissues of tumor-bearing mice were not different from those in the control mice. In contrast, the levels of tele-methylhistamine, one of the major catabolites of histamine, in the tumor-bearing mice increased significantly compared with the control mice in all four tissues examined. There was a correlation between the increase in tele-methylhistamine level and the increase in HDC activity in the tissues. A histological study indicated that the tissue mast cells were not increased in spleen and lung of tumor-bearing mice. These findings indicated that the increase in HDC activity in the spleen and lung occurred in parallel with the growth of inoculated tumor cells in mice and suggested that the cells other than mast cells may be involved in the increase in HDC activity. The tumor-bearing state produced histamine with a high turnover rate in the mouse tissues, especially in the spleen and lung.

Adenocarcinoma↗
PubMed1999

Locking of metacarpophalangeal joints in a patient with acromegaly.

A 39-year-old man with acromegaly exhibited locking of metacarpophalangeal (MCP) joints of both index fingers. Large osteophytes were found at the metacarpal heads by radiography and computerized tomography (CT). Magnetic resonance (MR) images revealed hypertrophy of volar plates. We suggest that these characteristic acromegalic features caused locking of MCP joints. Surgery was required on one of the joints to release the locking.

Acromegaly↗
PubMed1999

Gallbladder torsion: case report and review of 245 cases reported in the Japanese literature.

We report here a case of torsion of the gallbladder in a 73-year-old woman. The patient was admitted to our hospital with right hypochondralgia. Ultrasonography and computed tomography demonstrated a distended gallbladder, with a multilayered wall, which contained no stones. Since the symptoms did not respond to antibiotics, laparotomy was performed. The gallbladder was found to be twisted around its pedicle and to be gangrenous. Cholecystectomy was performed, and the patient had an uneventful postoperative course. We also reviewed 245 cases reported in the Japanese literature. The clinical features of gallbladder torsion, which include low frequency of fever and jaundice, poor response to antibiotic therapy, and acute onset of abdominal pain, may be helpful in the differential diagnosis from acute cholecystitis. Moreover, a highly suggestive sign of gallbladder torsion observed by ultrasonography or computed tomography is a markedly enlarged "floating" gallbladder with a continuous hypoechoic line indicating edematous change in the wall.

Abdomen, Acute↗
PubMed1999

Rapidly enlarging esophageal duplication cyst.

We report a rare esophageal duplication cyst, in a 12-year-old girl. The cyst had enlarged rapidly within 2 years. In December 1997, on admission, computed tomography and magnetic resonance imaging demonstrated a cystic mass in the pleural cavity. We resected the cyst and the adjacent lung. Histopathological examination revealed an esophageal duplication cyst. Her presenting symptoms of fever and cough may have been related to infection of the cyst.

Child↗
PubMed1999

Immunoblastic lymphadenopathy-like T-cell lymphoma complicated by multiple gastrointestinal involvement.

We report a rare case of immunoblastic lymphadenopathy (IBL)-like T-cell lymphoma complicated by multiple gastrointestinal involvement, which appeared to be ameliorated by chemotherapy but resulted in perforative peritonitis. A 66-year-old Japanese woman who had generalized lymphadenopathy and eruptions was admitted to our hospital because of bloody stool. Colonoscopic examination revealed hemorrhagic ulcers in the terminal ileum and a saucer-like ulcer in the cecum. Gastrointestinal endoscopy revealed several ulcerative or elevated lesions in stomach and duodenum. Biopsy specimens of these lesions and of a lymph node showed characteristic histological features of IBL-like T-cell lymphoma. The initial treatment with prednisolone (PSL) and cyclophosphamide (CPA) was effective. Six months after the treatment, however, she developed bloody stool again caused by multiple ulcerative lesions in the large intestine. The recurrence of the disease was determined histologically, and four courses of CPA, PSL, vinblastine sulfate and doxorubicin hydrochloride (CHOP) therapy were administered. One month after completing the CHOP therapy, she developed intestinal obstruction and then acute peritonitis resulting from perforation at an ulcer scar in the jejunum. Surgical treatment was successful, and histological examination demonstrated no lymphoma cells in the resected specimen. A gastrointestinal perforation should be recognized as a potential complication of IBL-like T-cell lymphoma, even during remission.

Aged↗
PubMed1999

Autologous blood transfusion with recombinant erythropoietin treatment in anaemic patients with rheumatoid arthritis.

The aim of this study was to determine the conditions under which a sufficient preoperative amount of autologous blood could be obtained with administration of rHuEPO (recombinant human erythropoietin) in anaemic patients with rheumatoid arthritis (RA). Thirty-one patients (29 female, two male) with RA who were unable to donate any autologous blood owing to a haemoglobin level of less than 11 g/dl were recruited for this study. Their mean age at the time of operation was 59.3 years. The study protocol for preoperative autologous blood donations started 2.7 weeks before surgery. All patients received 6000 IU rHuEPO intravenously three times a week, supplemented with 40 mg intravenous saccharated ferric oxide at each rHuEPO administration. The protocol also included the provision that 200 g of blood at the first and third donations and 400 g of blood at the second donation were collected. The patients who were able or unable to donate 800 g of blood by this protocol were regarded as having a good or poor response, respectively, to rHuEPO. Patients with a poor response to rHuEPO showed greater clinical symptoms (morning stiffness, the number of swollen joints, Ritchie index) and higher laboratory inflammation parameters (ESR, CRP, platelets, IL-6, TNFalpha, IL-1beta) than patients with a good response to rHuEPO. The poor-response group showed a significant decrease in the progression of inflammation compared with the good-response group. Before treatment with rHuEPO, anaemia in the poor-response group was the same as that in the good-response group, except for impairment of UIBC (unsaturated iron-binding capacity). The poor-response group had a higher blood loss than the good-response group. In conclusion, anaemic RA patients should be considered as candidates for aggressive blood conservation interventions that depend on erythropoietin-modulated erythropoiesis. However, it is important to determine this approach under good control of inflammation.

Aged↗
PubMed1999

Nitric oxide increases hepatic arterial blood flow in rats with carbon tetrachloride-induced acute hepatic injury.

BACKGROUND & AIMS: Little is known about the changes in hepatic blood flow associated with acute hepatic injury. The aim of this study was to investigate the effect of nitric oxide (NO) on hepatic blood flow and the severity of hepatic injury in rats with carbon tetrachloride (CCl4)-induced acute hepatic injury. METHODS: Rats were pretreated with CCl4 to induce acute hepatic injury. Hepatic blood flow was measured using a radioactive microsphere method. The role of NO in the regulation of hepatic blood flow and the severity of hepatic injury was investigated by administering NG-nitro-L-arginine (L-NNA) and aminoguanidine (AG). Plasma nitrite/nitrate levels, hepatic NO synthase (NOS) activity, and expression of hepatic NOS messenger RNA (mRNA) were measured, and histological examinations were performed. RESULTS: Hepatic arterial and portal venous blood flow was increased significantly by CCl4, without any change in mean arterial pressure or cardiac output. L-NNA and AG dose-dependently decreased hepatic arterial blood flow, with the highest dose resulting in complete blockade of hepatic arterial dilation, but failed to change portal venous blood flow. Histologically, administration of AG aggravated the hepatic injury in CCl4-treated rats. Plasma nitrite/nitrate levels and hepatic NOS activity were increased significantly by CCl4 treatment. Inducible NOS mRNA was detected in CCl4-treated rats but not in the controls. CONCLUSIONS: The results of this study suggest that the increased hepatic arterial blood flow in CCl4-induced acute hepatic injury is mediated by excessive NO production and up-regulated by inducible NOS, which plays a role in reducing hepatic injury.

Acute Disease↗
PubMed1999

Clinical efficacy of portal vein stent placement in patients with hepatocellular carcinoma invading the main portal vein.

BACKGROUND/AIMS: Hepatocellular carcinoma frequently invades the portal veins, and when it invades the main portal vein, the patient's prognosis is extremely poor. This study was undertaken to evaluate the clinical efficacy of stent placement into the portal vein in these patients. METHODS: Twenty-one patients with hepatocellular carcinoma invading the main portal vein were studied. Stents were placed in the portal veins to compress tumor thrombi after percutaneous transhepatic portography. RESULTS: Stents were successfully placed in the portal veins in all patients. Portal venous pressure significantly decreased from 25.3 +/- 7.4 mmHg to 22.4 +/- 6.6 mmHg (p < 0.0001) immediately after stent placement, leading to improvement in gastroesophageal varices, melena and ascites. Although a pseudoaneurysm of the hepatic artery related to portal vein puncture developed in one patient, there were no major complications in the other 20 patients. Blood flow through the stent was maintained during the survival period in 15 patients. The mean stent patency period was 12.4 months. Fifteen patients underwent transcatheter arterial chemoembolization without major complications after stent placement. The survival rate was 64.2% at 6 months and 29.2% at 1 and 2 years, respectively. The mean survival period was 13.7 months. CONCLUSION: Stent placement into the portal vein is a relatively safe and feasible procedure. It improves portal hypertension, expands treatment options, and helps to prolong the survival period in patients with hepatocellular carcinoma invading the main portal vein.

Aged↗
PubMed1999

Expression of platelet-derived growth factor B-chain and beta-receptor in hypoxic/ischemic encephalopathy of neonatal rats.

Expression of platelet-derived growth factor B-chain and of its specific receptor (beta-receptor) was investigated in immature brains with hypoxic/ischemic injury. After the left common carotid arteries of seven-day-old rats were ligated and pups were placed in a hypoxic chamber, the protein and messenger RNA of both B-chain and beta-receptor were assessed using immunocytochemistry and northern analysis, respectively. Transcripts for B-chain were localized by in situ hybridization. Faint but definite expression of B-chain and beta-receptor was seen in the brains of untreated neonatal controls. Three to 48 h after hypoxia B-chain protein was generally increased above control levels, but focally decreased expression was seen in infarcted areas. Enhanced induction of messenger RNA of B-chain was seen in the both sides of cerebral cortices and hippocampi at 3 h. Strongly increased positivity for B-chain protein and mRNA occurred in the neurons surrounding the infarct. In situ hybridization still showed this up-regulation seven days after hypoxia. Beta-receptor protein expression was enhanced in some neurons immediately surrounding the infarct at 3 h of hypoxia, and marked up-regulation was seen at 16 h. Beta-receptor messenger RNA remained at control levels. Immunocytochemistry showed strong immunoreactivity for the beta-receptor on the neurons surrounding the infarct at 72 h. These results indicate that a neonatal hypoxic/ischemic insult induces neuronal up-regulation of the platelet-derived growth factor B-chain as well as beta-receptor immediately after hypoxia. While this up-regulation is relatively transient in most neurons, sublethal damage to neurons immediately surrounding an infarct induces sustained up-regulation. Through autocrine and paracrine mechanisms, platelet-derived growth factor B-chain molecules may act as a neuroprotective factor in immature brain experiencing with hypoxic/ischemic injury.

Animals↗
PubMed1999

The size index as a motor unit identifier in electromyography examined by numerical calculation.

A computer simulation was performed to investigate the size index as a motor unit identifier in electromyography. The size index calculated from the amplitude and area of the simulated motor unit action potential (MUP) was plotted against the distance between the needle electrode and current source to show how the index changes as a function of the distance. The index of the MUP also was plotted against the number of muscle fibers belonging to a single motor unit, the size of the motor unit territory, and the diameter of the muscle fibers in order to establish the major determinants of the index. The index was relatively constant for the distance less than 2 mm between the needle electrode and closest edge of the current source. It changed logarithmically with the number of muscle fibers and with the diameter of the fibers.

Computer Simulation↗
PubMed1999

Long-term follow-up arterial chemoembolization combined with transportal ethanol injection used to treat hepatocellular carcinoma.

PURPOSE: This study was undertaken to evaluate the long-term efficacy of transcatheter hepatic arterial chemoembolization (TACE) combined with transportal ethanol injection (TPEI) in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty-six patients with unresectable HCC underwent TPEI 2-6 weeks after TACE. The size of the main tumor ranged from 2.0 to 9.0 cm (mean, 4.5 cm). Ethanol (10-65 mL) was injected via a percutaneous transhepatic approach into the portal vein, perfusing the segment to be treated. TACE was repeated after TPEI in 18 patients. RESULTS: The combined therapy was technically successfully in all 26 cases; however, irreversible hepatic failure developed in two (8%) patients. Recurrent disease occurred either from the treated lesion (four patients) or apart from the treated liver segment (five patients) in nine of 21 patients (43%) followed up for a mean of 34 months. The survival rates were 87%, 72%, 72%, 63%, 51, and 51% at 1, 2, 3, 4, 5, and 6 years, respectively. Resected and autopsied specimens showed complete necrosis in seven of nine main lesions and severe parenchymal damage in the treated liver segment. CONCLUSION: In selected patients, combined treatment with TACE and TPEI is safe and effective, decreasing recurrence rate in the treated segment, and resulting in a 51% 6-year survival.

Aged↗
PubMed1999

Clinical features and management of oral and maxillofacial tumors in children.

OBJECTIVE: To clarify the characteristics of oral and maxillofacial tumors in children, we carried out a clinical study of such tumors and reviewed the relevant procedures for treatment. Study design. Medical records of 105 patients less than 15 years of age who were treated for oral and maxillofacial tumors during the 20 years between 1976 and 1997 were retrieved and analyzed. RESULTS: Of the 105 cases, 102 (97.1%) involved tumors that were benign; only 3 patients (2.9%) had tumors that were malignant. With regard to benign soft tissue tumor, the most common type was hemangioma (25/69; 36.2%), the second most common type was papilloma (19/69; 27.5%), and the most common site was the tongue. With regard to bone tumor, the most common type was odontoma (14/33; 42.4%), the second most common type was ameloblastoma (11/33; 33.3%), and the most common site was the mandible. Most of the odontogenic tumors (25/28; 89.3%) developed in patients more than 6 years of age; these tumors may develop after dental crown formation. In each case of benign soft tissue tumor, resection was performed; 4 of these tumors (2 hemangiomas, 1 lymphangioma, and 1 papilloma) recurred, but after re-resection recurrence has not been found for more than 4 years. In the cases of benign jawbone tumor, resection and enucleation were the procedures principally performed; 3 ameloblastomas recurred after enucleation, but after relatively wide resection for these recurrent tumors there has been no recurrence for more than 17 years. With regard to the ameloblastomas, enucleation with preservation of the periosteum was effective and bone regeneration occurred rapidly. CONCLUSIONS: Most oral and maxillofacial tumors in children are benign. In any case of such benign tumor, including ameloblastoma, minimal surgical treatment should be the procedure of first choice.

Adolescent↗