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Biomedical subjects

T Higashiguchi

Publications and source records attributed to T Higashiguchi.

At least 19 recordsLinked to original sources
PubMed2002

Experimental observation of radiation from cherenkov wakes in a magnetized plasma.

A proof-of-principle experiment demonstrates the generation of radiation from the Cherenkov wake excited by an ultrashort- and ultrahigh-power pulse laser in a perpendicularly magnetized plasma. The frequency of the radiation is in the millimeter range (up to 200 GHz). The intensity of the radiation is proportional to the magnetic field intensity as expected by theory. Polarization of the emitted radiation is also detected. The difference in the frequency of the emitted radiation between these experiments and previous theory can be explained by the electrons' oscillation in the electric field of a narrow column of ions in the focal region.

Journal Article↗
PubMed2000

Experimental observation of further frequency upshift from dc to ac radiation converter with perpendicular dc magnetic field

A frequency upshift of a short microwave pulse is generated by the interaction between a relativistic underdense ionization front and a periodic electrostatic field with a perpendicular dc magnetic field. When the dc magnetic field is applied, further frequency upshift of 3 GHz is observed with respect to an unmagnetized case which has typically a GHz range. The radiation frequency depends on both the plasma density and the strength of the dc magnetic field, i.e., the plasma frequency and the cyclotron frequency. The frequency of the emitted radiation is in reasonable agreement with the theoretical values.

Journal Article↗
PubMed2000

Surgical treatment for hilar cholangiocarcinoma.

From September 1976 to February 1998, we experienced 75 resected patients with hilar cholangiocarcinoma. Curative resection was performed in 45 patients (60.0%), with a cumulative 5-year survival rate of 39.8%. In this retrospective study, we compared therapeutic outcomes in these 75 patients according to the period during which they were treated; (1) 12 patients in the early period (September 1976 to August 1981) chiefly treated by bile duct resection, (2) 50 patients in the middle period, September 1981 to August 1994, chiefly treated by aggressive surgical procedures with extensive hepatectomy plus caudate lobe resection, and (3) 13 patients in the late period, September 1994 to February 1998, during which percutaneous transhepatic portal embolization was introduced to increase the safety and curability of extended hepatectomy, and limited hepatectomy was selected according to tumor spread. In the late period, total resection of the caudate lobe was done in all patients, with the aim being thorough resection of cancer cells in the caudate lobe. The curative resection rates were 16.7% in the early period, 64.0% in the middle period, and 84.6% in the late period, showing an improvement year-by-year (P<0.05; early period vs middle period and late period). All patients in the early period died within 2 years of resection, whereas the 5-year survival rate in the middle period was 24.4%, significantly improved (P<0.05) compared with the early period. The 1- and 3-year survival rates of 84.6% and 58.0%, respectively, in the late period, show an even greater improvement in outcome.

Adult↗
PubMed1999

Effects of glutamine administration on liver regeneration following hepatectomy.

The intestine is now known to be an important site of protein production in the body, and glutamine (GLN) stimulates both secreted and non-secreted protein synthesis in the small bowel. The purpose of the present study was to evaluate the effect of GLN-supplemented parenteral nutrition on liver regeneration after hepatectomy. Animals were divided into two groups: a sham-operated control group (Group A) and a 70%-hepatectomy group (Group B). Postoperatively, one-third of the animals in each group were maintained on intravenous 10% glucose solution, on 10% glucose with 2% standard amino acid solution, or 10% glucose supplemented with 2% glutamine for 24 h. GLN administration after hepatectomy significantly promoted liver regeneration. In addition, assessment of amino acid metabolism showed that GLN administration activated GLN metabolism in the intestine and promoted alanine uptake by the remnant liver. This metabolic response also enhanced both secreted and non-secreted protein synthesis in intestinal epithelial cells, especially in cells isolated from the crypts. The proteins produced are important as a portal production factor for liver regeneration and intestinal cell proliferation. Bacterial and endotoxin translocation, on the other hand, was significantly reduced. Thus, the results of this study suggest that intravenous administration of GLN after hepatectomy significantly promoted liver regeneration.

Amino Acids↗
PubMed1999

Breast cancer with choriocarcinomatous features: A case report with cytopathologic details.

A case of breast cancer with choriocarcinomatous features (BCCF) is reported. The patient was a 38-year-old Japanese female with a long history of schizophrenia. Her nursing staff noticed a palpable mass in her right breast, which showed rapid growth. Following cytopathologic confirmation of a malignant breast tumor, she underwent mastectomy with ipsilateral axillary lymph node dissection. Histologic examination revealed BCCF, which was positive for placental alkaline phosphatase and human chorionic gonadotropin (HCG) by immunohistochemistry. The serum HCG level was high. She died 7 months postoperatively, with multiple metastases of BCCF to the chest wall, lung and liver.

Adult↗
PubMed1999

Prospective study of a protocol for selection of treatment of acute pancreatitis based on scoring of severity.

BACKGROUND/AIM: Since July 1994, we have been conducting a prospective study of a protocol for selection of treatment of acute pancreatitis based on scoring of severity. METHODS: From July 1994 to June 1998, 56 patients with acute pancreatitis were enrolled in this study. The protocol employed was based on the results of our retrospective study. On admission, the prognosis score (scoring of severity of acute pancreatitis based on the criteria of the Ministry of Health and Welfare of Japan) and APACHE II score were calculated, and early treatment was selected according to the protocol. RESULTS: All of the 26 patients with gallstone pancreatitis and 28 of 30 patients with non-gallstone pancreatitis were successfully treated and had good outcome. There were 2 deaths in non-gallstone pancreatitis. In selection of early treatment according to the scoring of severity, we suggested that when the prognosis score is 2 or more and the APACHE II score of 8 or more, gallstone pancreatitis should be treated by biliary drainage, and non-gallstone pancreatitis by peritoneal lavage. When infected pancreatic necrosis is exhibited, surgery is indicated. CONCLUSION: Our new management protocol for acute pancreatitis based on the prognosis score and APACHE II score appear to be useful for accurately scoring severity and selecting the treatment methods.

Acute Disease↗
PubMed1999

Effect of IS-741 (a new synthetic antiinflammatory agent) on acute necrotizing pancreatitis in dogs. Significance of its inhibitory effect on cytosolic phospholipase A2.

IS-741, a new synthetic anti-inflammatory agent, is known to have some inhibitory effect on cytosolic phospholipase A2 (cPLA2), an enzyme which hydrolyzes cellular phospholipids, liberating fatty acids and lysophospholipids and providing the precursor substrates for the biosynthesis of eicosanoids and platelet-activating factor. cPLA2 is therefore an attractive target for the development of novel therapies. During infusion of lactated Ringer's solution at a rate of 10 ml/kg/h, acute pancreatitis was induced in dogs by injecting autologous gallbladder bile into the main pancreatic duct. The dogs were then divided into two groups: group A (nontreatment), no treatment during the experiment, and group B (IS-741), intravenously injected with IS-741 at 6 and 30 h after induction of acute pancreatitis. As a result, the survival rate was significantly higher in group B than in group A. Mean arterial pressure and PaO2 were well maintained in group B as compared with group A. The NAG index, which is known to be markedly increased in renal tubular damage, was significantly lower in group B than in group A. Histological examination of the pancreas, lung, and kidney in group B showed milder changes than in group A. cPLA2 activity in the pancreas, lung and renal cortex was much lower in group B than in group A, but sPLA2 activity in these tissues did not differ significantly between the two groups. In conclusion, IS-741 exerts a potentially therapeutic effect on experimental acute pancreatitis by mitigating the degree of damage in the pancreas, lung, and kidney. The inhibitory effect of IS-741 on cPLA2 may contribute to one of the antiinflammatory mechanisms of actions of this agent.

Animals↗
PubMed1998

Matrix-producing carcinoma of the breast: case report with radiographical and cytopathological features.

A case of matrix-producing carcinoma (MPC), which is a unique variant of breast cancer, is described with cytopathological and radiographical findings. A 75-year-old female presented with a palpable mass in her right breast. After confirmation of the cytopathological diagnosis, the patient received a right mastectomy with ipsilateral axillary lymph node dissection. The histopathological examination revealed MPC. The Union Internationalis Contra Cancrum postoperative clinical stage was IIB. The patient is well and without disease 18 months after the surgery.

Aged↗
PubMed1996

Overexpression of different members of the type 1 growth factor receptor family and their association with cell proliferation in periampullary carcinoma.

The expression of epidermal growth factor receptor (EGFR), c-erbB-2, and c-erbB-3 was examined immunohistochemically in 57 cases of periampullary carcinoma. The percentage of Ki-67-positive cells was also examined in the same tissue, to determine the relationship between the expression of the members of the type I growth factor receptor family and cell proliferation. In carcinoma of the head of pancreas, the percentage of cases with overexpression of c-erbB-3 was significantly higher than with overexpression of c-erbB-2 and EGFR. In contrast, in lower bile duct carcinoma and carcinoma of the ampulla of Vater, the percentages of cases with overexpression of c-erbB-2 was greater than with overexpression of other growth factor receptors. A higher percentage of cases with overexpression of c-erbB-3 in pancreatic head carcinoma and overexpression of c-erbB-2 in carcinoma of the ampulla of Vater was found in Ki-67 antigen-positive cases. Moreover, the overexpression of c-erb-3 in pancreatic head carcinoma, c-erb-2 in ampulla of Vater carcinoma, and Ki-67 in both carcinomas was found to be associated with poor patient outcome. These results demonstrate that different members of the type I growth factor receptor family are overexpressed in different carcinomas of the periampullary region.

Adenocarcinoma↗
PubMed1996

Therapeutic effects of continuous intraarterial antibiotic infusion in preventing pancreatic infection in experimental acute necrotizing pancreatitis.

To determine the efficacy of antibiotics in the prevention of pancreatic infection and the process of aggravation after induction of acute pancreatitis, antibiotic was administrated intravenously or intraarterially, starting 6 h after acute pancreatitis was induced in dogs by injecting autologous gallbladder bile into the main pancreatic duct. Flomoxef, recognized as an antibiotic able to penetrate well into pancreas tissue, was selected for the present study. Animals were divided into three groups: no antibiotic given (Group A), antibiotic given intravenously as a bolus injection of 25 mg/kg every 6 h (Group B), and antibiotic infused continuously into the celiac trunk (4 mg/kg/h) (Group C). Compared with Group A, continuous intraarterial infusion of antibiotic (Group C) significantly improved the survival rate and decreased the serum levels of phospholipase A2(PLA2) activity and endotoxin. Furthermore, it completely prevented the occurrence of pancreatic infection, not only ameliorating the severity of pancreatic necrosis but also reducing the activity levels of amidase, trypsin-like enzyme, and PLA2 in pancreas tissue. Group B showed little beneficial effect. Antibiotic concentration in peripheral blood and pancreas tissue was significantly higher in Group C than in Group B. These results suggest that continuous arterial infusion of antibiotics into the feeding artery of the pancreas is an effective modality for preventing pancreatic infection and aggravation of severe acute pancreatitis.

Amidohydrolases↗
PubMed1995

The preoperative nutritional assessment of surgical patients with hepatic dysfunction.

The precise influence of malnutrition on postoperative complications in patients with hepatic dysfunction is not well known. In phase I of the present study, we evaluated the nutritional status of 102 patients with hepatic dysfunction who were admitted for elective hepatobiliary or pancreatic surgery, and a model for the prediction of postoperative complications was developed using a computer-based stepwise regression procedure. The equation for this Prognostic Nutritional Index for Surgery (PNIS) was calculated by [-0.147 x (% weight change) + 0.046 x (% ideal body weight) + 0.010 x (actual triceps skinfold thickness as a % of standard value) + 0.051 x (hepaplastintest)]. In phase II this model was prospectively tested in 182 patients, including 145 with hepatic dysfunction. A total of 18 patients were classified as having a poor prognosis (PNIS < 5) and all of these patients in fact developed postoperative complications: 128 patients were classified as having an intermediate prognosis (5 < or = PNIS < 10), 23 (18.0%) of whom developed postoperative complications, and none of the 36 patients who were classified as having a good prognosis (PNIS > or = 10) developed any postoperative complications. These results demonstrate the importance of performing a thorough preoperative nutritional assessment of patients with hepatic dysfunction as malnourished patients with PNIS < 10 may need preoperative nutritional management, even when their surgical procedures are not major.

Humans↗
PubMed1995

Protein synthesis in isolated enterocytes from septic or endotoxaemic rats: regulation by glutamine.

1. We studied the effect of sepsis and the regulation by glutamine of protein synthesis in enterocytes isolated from the small intestine of rats. 2. Sepsis was induced by caecal ligation and puncture; control rats were sham operated. Enterocytes were isolated from the jejunum and incubated in a medium containing [3H]phenylalanine. 3. Sixteen hours after caecal ligation and puncture, protein synthesis, measured as incorporation of radioactivity into protein, was increased by 65%, 89% and 137% respectively in enterocytes from the tips and mid-portions of the villi and from the crypts. 4. Addition of glutamine to incubated enterocytes stimulated protein synthesis in a dose-dependent manner, and this effect was most pronounced in crypt cells from septic rats. The effect of glutamine on protein synthesis was duplicated by equimolar concentrations of acetoacetate or 3-hydroxybutyrate, both of which may serve as fuel for enterocytes, and was blocked by the glutaminase inhibitor 6-diazo-5-oxo-L-norleucine. 5. The results suggest that sepsis stimulates protein synthesis in enterocytes and that glutamine regulates protein synthesis in the same cells, probably by energy provision.

Animals↗
PubMed1994

Sepsis increases production of total secreted proteins, vasoactive intestinal peptide, and peptide YY in isolated rat enterocytes.

The effect of sepsis on the synthesis of endogenous and secretory proteins, including vasoactive intestinal peptide (VIP) and peptide YY (PYY), was determined in enterocytes from jejunum of rats. Sepsis was induced by cecal ligation and puncture (CLP). Control rats were sham-operated. Total endogenous and secreted protein synthesis was assessed in incubated jejunal enterocytes by measuring incorporation of 3H-phenylalanine into protein. Release of VIP and PYY into the medium of incubated enterocytes and cellular levels of the gut peptides were measured by radioimmunoassay. Sixteen hours after CLP, synthesis rates of both endogenous and secreted proteins were increased, and this effect of sepsis was most pronounced in cells from the lower parts of the villi and crypts. Enterocytes from septic rats released more VIP and PYY into the incubation medium, and approximately half of the peptides they released were newly synthesized VIP and PYY. Intracellular levels of VIP and PYY were increased as early as 4 hours after induction of sepsis. Our results suggest that sepsis stimulates the synthesis of endogenous and secretory proteins, including certain gut peptides, in small intestine mucosa. This is consistent with previous observations of increased circulating levels of VIP, PYY and other gastrointestinal hormones during sepsis. The biological significance of increased synthesis of gut peptides and other intestinal proteins during sepsis remains to be determined.

Analysis of Variance↗
PubMed1994

Effect of sepsis on mucosal protein synthesis in different parts of the gastrointestinal tract in rats.

1. In a previous study we found that the protein synthesis rate was increased by 50-60% in the mucosa of the jejunum and ileum during sepsis in rats. It is not known if sepsis affects protein turnover in other parts of the gastrointestinal tract as well. 2. In the present study, the influence of sepsis on mucosal protein synthesis in different parts of the gastrointestinal tract, from the stomach to the rectum, was determined in rats. 3. Sepsis was induced by caecal ligation and puncture; control rats underwent sham-operation. Protein synthesis rate was measured in vivo after administration of a flooding dose of [14C]leucine. 4. Basal mucosal protein synthesis rates were lower in the colon than in the rest of the gastrointestinal tract. Sixteen hours after caecal ligation and puncture, the protein synthesis rates were increased by 40-85% in the mucosa of the small and large intestine and the rectum, whereas in the gastric mucosa, the protein synthesis rate was reduced by approximately 40%. 5. The results suggest that mucosal protein synthesis rates differ in the various regions of the gastrointestinal tract, and that the metabolic response to sepsis is different in the stomach than in the rest of the gastrointestinal tract. The finding of a reduced protein synthesis rate in the gastric mucosa may partly explain the tendency to gastric stress ulcers and bleeding seen clinically in sepsis.

Animals↗