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Biomedical subjects

H Takamori

Publications and source records attributed to H Takamori.

At least 19 recordsLinked to original sources
PubMed2002

Quiet MRI with novel acoustic noise reduction.

Fast scan techniques, which are used to reduce scanning times, have raised scanning noise levels in magnetic resonance imaging (MRI) systems, resulting in greater patient discomfort and stress. It is well known that this noise is caused by vibration of the gradient coil due to the Lorentz forces generated by the current in the gradient coil, which is placed in a static magnetic field. We have confirmed that MRI noise can be substantially reduced by sealing the gradient coil in a vacuum chamber to block airborne vibration propagation, by supporting the gradient coil independently to block solid vibration propagation and by decreasing the eddy currents induced in RF coils, the RF shield and the static-field-magnet cryostat. Based on these findings, we have developed a silent MRI system in which scanning noise is markedly reduced under a wide range of scanning conditions.

Electromagnetic Fields↗
PubMed2001

Lymphatic spreading pattern of intrahepatic cholangiocarcinoma.

BACKGROUND: There have been very few reports on the pattern of lymphatic spread of intrahepatic cholangiocarcinoma. This pattern was elucidated to help define the rational extent of radical lymph node dissection. METHODS: Thirty-nine consecutive patients who underwent hepatectomy with radical lymph node dissection were reviewed retrospectively. RESULTS: Lymph node metastases were detected in 24 of the 39 patients (62%). The metastatic nodes were found in the hepatoduodenal ligament, along the common hepatic artery, around the abdominal aorta, on the posterior surface of the pancreas head, along the left gastric artery, along the superior mesenteric artery, around the celiac artery, along the lesser curvature of the stomach, and around the cardia. The nodal involvements along the left gastric artery, along the lesser curvature, or around the cardia were recognized only in the left peripheral and hilar types of cholangiocarcinoma, while all other sites included both the left or right peripheral type and the hilar type cholangiocarcinoma. CONCLUSIONS: Intrahepatic cholangiocarcinomas, irrespective of their intrahepatic location, mainly spread to the nodes in the hepatoduodenal ligament, then to the para-aortic nodes, retropancreatic nodes, or common hepatic artery nodes. In addition to these spreading routes, the left peripheral type or hilar type of cholangiocarcinoma tends to spread along the left gastric nodes through the lesser curvature.

Adult↗
PubMed2001

Human CC chemokine liver-expressed chemokine/CCL16 is a functional ligand for CCR1, CCR2 and CCR5, and constitutively expressed by hepatocytes.

Liver-expressed chemokine (LEC)/CCL16 is a human CC chemokine selectively expressed in the liver. Here, we investigated its receptor usage by calcium mobilization and chemotactic assays using mouse L1.2 pre-B cell lines stably expressing a panel of 12 human chemokine receptors. At relatively high concentrations, LEC induced calcium mobilization and chemotaxis via CCR1 and CCR2. LEC also induced calcium mobilization, but marginal chemotaxis via CCR5. Consistently, LEC was found to bind to CCR1, CCR2 and CCR5 with relatively low affinities. The binding of LEC to CCR8 was much less significant. In spite of its binding to CCR5, LEC was unable to inhibit infection of an R5-type HIV-1 to activated human peripheral blood mononuclear cells even at high concentrations. In human liver sections, hepatocytes were strongly stained by anti-LEC antibody. HepG2, a human hepatocarcinoma cell line, was found to constitutively express LEC. LEC was also present in the plasma samples from healthy adult donors at relatively high concentrations (0.3--4 nM). Taken together, LEC is a new low-affinity functional ligand for CCR1, CCR2 and CCR5, and is constitutively expressed by liver parenchymal cells. The presence of LEC in normal plasma at relatively high concentrations may modulate inflammatory responses.

Animals↗
PubMed2001

Genetic variation and correlations among responses to five insecticides within natural populations of Drosophila melanogaster (Diptera: Drosophilidae).

To investigate the genetic basis of cross-resistance to insecticides, natural populations of Drosophila melanogaster (Meigen) were first collected from four different locations in Japan. After 10-80 isofemale lines of each population had been established in a laboratory, the susceptibility of each line to each of the insecticides permethrin, malathion, fenitrothion, prothiophos, and DDT was examined. Broad ranges of continuous variation in susceptibility to all the chemicals were observed within each natural population as a whole. In addition, highly significant correlations among responses to organophosphates were observed. However, based on the coefficients of determination, about less than half of variation in responses to one insecticide could be explained by variation in responses to another insecticide, suggesting that not only a common resistance factor but also other factors could be involved in a natural population. Genetic analyses by using resistant and susceptible inbred lines from the same natural population demonstrated that resistance to organophosphates in some resistant lines could be due to a single or tightly linked factors, and that resistance in the other line may be due to more than one major factor. These observations could suggest that several resistance factors may be involved within each natural population, and that some of major factors could contribute to correlations among responses to organophosphates. These major factors could then contribute to the broad ranges of continuous variation observed at the level of the populations.

Animals↗
PubMed2000

Autocrine growth effect of IL-8 and GROalpha on a human pancreatic cancer cell line, Capan-1.

A human pancreatic cancer cell line, Capan-1, secretes the chemokines interleukin-8 (IL-8) and growth-related oncogene alpha (GROalpha). Capan-1 cells also express the chemokine receptor 2 (CXCR2), which is a Gialpha-protein coupled receptor. Growth of Capan-1 cells was inhibited when anti-IL-8 or anti-GROalpha monoclonal antibody was added into the culture medium. Pertussis toxin, which blocks Gialpha also demonstrated a growth-inhibitory effect on Capan-1 cells. These results indicated that IL-8 and GROalpha act on Capan-1 cells as growth factors in an autocrine manner through CXCR2.

Antibodies, Monoclonal↗
PubMed1999

Point mutation causing constitutive signaling of CXCR2 leads to transforming activity similar to Kaposi's sarcoma herpesvirus-G protein-coupled receptor.

The chemokine receptor CXCR2 is the closest homologue to Kaposi's sarcoma herpesvirus-G protein-coupled receptor (KSHV-GPCR), which is known to be constitutively activated and able to cause oncogenic transformation. Among G protein-coupled receptors, a DRY sequence in the second intracellular loop is highly conserved. However, the KSHV-GPCR shows a VRY sequence instead. In this study, we exchanged Asp138 of the DRY sequence in the CXCR2 with a Val (D138V), the corresponding amino acid in KSHV-GPCR, or with a Gln (D138Q), and investigated the functional consequences of these mutations. In focus formation and soft agar growth assays in NIH 3T3 cells, the D138V mutant exhibited transforming potential similar to the KSHV-GPCR. Surprisingly, the CXCR2 wild type itself showed transforming activity, although not as potently, due to continuous autocrine stimulation, whereas the D138Q mutant formed no foci. In agreement with these results were high levels of inositol phosphate accumulation in the D138V mutant and the KSHV-GPCR, indicating constitutive activity. These data emphasize the importance of the DRY sequence for G protein-coupled signaling of the CXCR2. Either constitutive activation or persistent autocrine stimulation of the CXCR2 causes transformation similar to KSHV-GPCR-transfected cells, probably activating the same signal transduction cascade that can abrogate normal growth control mechanisms.

3T3 Cells↗
PubMed1998

Importance of the carboxy-terminus of the CXCR2 for signal transduction.

The CXCR2 is phosphorylated at the C-terminal intracytoplasmic portion within 15 sec following the addition of IL-8 or MGSA. Cells transfected with a truncated form of the receptor missing the last 12 amino acids (T3) showed normal binding affinity, but were no longer phosphorylated; individual alanine replacement indicated that Ser346 and 348 were the primary sites of phosphorylation. In studies of the importance of phosphorylation in CXCR2 desensitization, cells expressing wild type CXCR2 lost GTP gamma S binding above basal rate after the first exposure to IL-8, while cells with the T3 mutant retained 60% of their capacity to induce GTP gamma S exchange upon a second exposure to IL-8. In contrast, receptor internalization was not affected by the loss of phosphorylation of the T3 mutant. Further receptor truncation led to decreasing binding affinities for IL-8 and MGSA and a decreased rate of GTP gamma S exchange following addition of excess ligand which suggests involvement of this region in G-protein coupling.

Amino Acid Sequence↗
PubMed1998

Modulation of bone mass, strength, and turnover by a new benzamide compound, DU-6712, in adjuvant-induced arthritic rats.

To assess the reductions in bone mass, strength, and turnover in adjuvant-induced arthritic rats and to examine the effect of a new benzamide compound, DU-6712, on these parameters, a 28-day dosing experiment was performed using 8-week-old female Lewis rats. Arthritis was induced by injecting the adjuvant into the hind paw. The age-dependent increases in the body weight, lumbar bone mineral content and density (BMC and BMD) and compressive strength were disturbed in the arthritic rats. At 14 days, the histomorphometric parameters of bone formation (BFR/BS and BFR/BV) and the serum osteocalcin levels were significantly reduced compared with the baseline controls. However, the BMC values corrected for body weight did not differ significantly between the arthritic and normal rats, and the bone minerals were not reduced compared with the baseline controls. At 28 days, the parameters of bone minerals and strength of the lumbar body in the arthritic rats, both with and without correction for body weight, were significantly reduced compared with the baseline controls. The trabecular mineralizing surface remained significantly reduced and the osteoclast numbers were increased. DU-6712 at the doses of 5, 15, and 45 mg/kg, orally administered daily from the start of the experiment, significantly prevented the development of the chronic paw edema at 28 days. The reductions in the parameters of bone minerals, strength, and trabecular bone formation, and the increase in osteoclast number were alleviated by this agent. Age-dependent increases in the lumbar height, disturbed by the adjuvant injection, were also maintained. These data indicated that a 28-day period is necessary to obtain sufficient reductions in the bone mass and strength of the lumbar body concerning the model of secondary osteoporosis in adjuvant arthritic rats. DU-6712 was able to prevent these reductions by modulating the bone turnover in this arthritis model.

Animals↗
PubMed1998

Bronchoalveolar lavage with KL4-surfactant in models of meconium aspiration syndrome.

As a model of the meconium aspiration syndrome (MAS) of human infants, adult rabbits and newborn rhesus monkeys received intratracheal instillation of human meconium to induce pulmonary injury. Injured rabbits were ventilated with 100% O2 and divided into four treatment groups, receiving: 1) bronchoalveolar lavages (BAL) with dilute KL4-Surfactant; 2) lavages with equal volumes of sterile saline; 3) a single intratracheal bolus of KL4-Surfactant, 100 mg/kg; and 4) no treatment. The untreated rabbits developed atelectasis, a fall in pressure-volume levels and in partial pressure of O2 in arterial blood (PaO2) from approximately 500 to < 100 mm Hg, and severe pulmonary inflammation between 3 and 5 h after instillation of meconium. Rabbits treated by BAL with dilute KL4-Surfactant showed rapid and sustained recovery of PaO2 to approximately 300 mm Hg within minutes, a return toward normal pressure-volume levels, and diminished inflammation. Rabbits receiving BAL with saline failed to show recovery, and rabbits treated with a bolus of surfactant intratracheally exhibited a transient response by 1-2 h after treatment, but then returned to the initial atelectatic state. Newborn rhesus monkeys, after receiving human meconium intratracheally before the first breath, developed severe loss of pulmonary function. Treatment of these monkeys 1-5 h after birth with BAL with dilute KL4-Surfactant produced clearing of chest radiographs and a rapid improvement in pulmonary function with ratios of partial pressure of O2 in arterial blood to the fraction of O2 in the inspired air rising into the normal range where they remained through the 20-h period of study. The studies indicate that pulmonary function in two models of severe meconium injury respond rapidly to BAL with dilute KL4-Surfactant.

Animals↗
PubMed1994

The combination of lovastatin and enalapril in a model of progressive renal disease.

Puromycin-induced nephrotic syndrome is an animal model of progressive renal disease. Both angiotensin converting enzyme inhibitors and lipid-lowering agents have been used to preserve renal structure and function in this model, although neither completely prevents progression. We tested the hypothesis that the combination of the two agents would be more protective than either alone. Rats were divided into five groups; all were uninephrectomized. Four groups were given puromycin at a dose of 10 mg/100 g body weight (BW) with additional doses of 4 mg/100 g BW given intraperitoneally at 4, 5, and 6 weeks thereafter. One group was given enalapril (EN) 50 mg/l dissolved in the drinking water; the second received lovastatin (L) 15 mg/kg given daily by gavage; the third received both agents; the fourth was left untreated, and the final group received no puromycin and served as the control group. Eight weeks after the initial dose of puromycin, glomerular filtration rate (GFR), as inulin clearance, and protein excretion were determined and blood was collected for cholesterol and triglycerides. Blood pressure was not different between any of the groups. At the end of the study period, serum cholesterol [mean +/- SD, 252 +/- 185 mg/dl (L), 135 +/- 101 mg/dl (L + EN)] and triglycerides (239 +/- 200, 148 +/- 158 mg/dl) were significantly lower (P < 0.001) in the lovastatin-treated groups than in the untreated puromycin group (535 +/- 255 mg/dl and 579 +/- 561 mg/dl, cholesterol and triglyceride, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Treatment strategies for hepatic metastases from pancreatic cancer in patients previously treated with radical resection combined with intraoperative radiation therapy.

Since 1984, we have performed extended radical resection combined with extended intraoperative radiation therapy (IORT) for pancreatic cancer. This approach has provided a dramatic improvement in long-term survival and control of local recurrence. Hepatic metastases, however, remain an unsolved problem. Among patients with this combined therapy, we found hepatic metastases in 8 of 22 patients postoperatively. Four of these 8 were considered candidates for further therapy and underwent treatment for their hepatic metastases, the other 4 had too extensive disease. Two patients with multiple hepatic metastases underwent percutaneous ethanol injection therapy and chemotherapy, but they died within a year. Two patients with a solitary hepatic metastases underwent hepatic resection. One patient died two years and six months after the first operation because of multiple metastases in the liver and both lungs, while the other patient is still alive over six years after the first operation with an excellent performance status. When a patient has no local recurrence and a solitary metastasis in the liver, surgical resection of the liver metastasis should be performed.

Adenocarcinoma↗
PubMed1993

A method for safe pancreaticojejunostomy.

We devised a new technique to increase the safety of pancreaticojejunostomy in patients with an extended operation for pancreatic cancer. This new pancreaticojejunostomy was created by end-to-side anastomosis with four layers about 7 cm distal to the jejunal stump. The cut surface of the pancreas was placed on the seromuscular coat of the ventral aspect of the jejunum to cover the posterior surface of the anastomosis, and the anastomosis between the pancreas and the jejunum was created using fibrin glue. The pancreatic duct was intubated with a silicone tube, and its stenting tube was brought out through a opening in the jejunum. The anterior surface of the pancreaticojejunostomy was covered by the proximal jejunum as a serosal patch. We used this technique in seven patients. No patient developed an anastomotic leak or any other complication. The anastomosis is covered by the jejunum and is not open to the peritoneum. This new technique of pancreaticojejunostomy may reduce the risk of pancreatic leak, especially when an extended operation is performed.

Humans↗
PubMed1993

Cell-mediated transfer of collagen-induced arthritis in mice and its application to the analysis of the inhibitory effects of interferon-gamma and cyclophosphamide.

We developed a convenient and reliable procedure for the cell-mediated passive transfer of type II collagen (CII)-induced arthritis (CA). Spleen cells from DBA/1 mice with CA were intravenously transferred into syngeneic recipient mice. Arthritis developed only in those recipients which had received whole-body x-irradiation (8 Gy) just before cell transfer and intraperitoneally given soluble CII without adjuvant immediately after transfer. Non-immunized splenocytes could not induce arthritis even in irradiated recipients given soluble CII. Development of arthritis depended on the number of cells transferred; 5 x 10(7) cells induced severe and long-lasting arthritis in every recipient approximately 10 days after transfer. Severity of this arthritis was clinically and histologically similar to classical CA in donors. Arthritogenic splenocytes were generated in donors no later than 20 days after priming with CII in Freund's complete adjuvant, when arthritis had yet to occur, and were detected for more than 5 weeks. One splenocyte population responsible for transferring arthritis was CD4+ T cells. We then applied this system to show that prophylactic treatment of CII-immunized mice with cyclophosphamide (CY, 7 mg/kg), but not interferon-gamma (IFN-gamma, 10(5) U/mouse), suppressed the arthritogenic ability of their spleen cells, although both treatments inhibited the development of CA. Treatment of recipients with IFN-gamma, however, inhibited the development of arthritis upon transfer with CII-immunized splenocytes. These results indicate that CY and IFN-gamma act at the induction and effector phases of arthritogenic lymphocytes, respectively. Thus, this system facilitates investigation of pathological mechanisms of CA, and of mechanisms of anti-arthritics.

Animals↗
PubMed1993

Differentiation of hematuria using a uniquely shaped red cell.

Although variously shaped urinary red cells have been reported in glomerulonephritic hematuria, no specific shapes with concrete definition have been proposed. This made morphological differentiation of hematuria vague and caused different results among different observers. To solve these problems and improve the diagnostic rate, we employed a uniquely shaped red cell, which only appeared in glomerulonephritic hematuria, as a probe for diagnosis. We studied 182 hematuria cases from 90 glomerulonephritic patients and 95 hematuria cases from 68 urological disease patients. Fresh urine was collected and observed by differential interference microscopy. The red cell, referred to as G1, has a distinctive doughnut-like shape with blebs and was highly specific for glomerulonephritic hematuria. Occurrence of G1 cells increased at lower pH an higher osmolality of urine. A presence of 5% or more G1 cells could be an indicator of glomerulonephritic hematuria. Specificity and sensitivity of this criterion were 100 and 73%. However, when only acidic concentrated urine (pH < or = 6.4, osmolality > or = 400 mosm/kg H2O) was used, the specificity and sensitivity increased to 100 and 99.2%, respectively. Glomerulonephritic and urological hematuria were correctly diagnosed by counting the urinary red cells with doughnut-like shape in acidic and concentrated urine. This method seems to be superior to others in diagnostic rate, simplicity and clarity.

Adolescent↗
PubMed1993

Effects of DS-4574, a new orally active antiallergic agent, in experimental allergic and inflammatory models.

The anti-allergic and anti-inflammatory activities of DS-4574, which possesses leukotriene antagonism and inhibits the release of immunologically stimulated mediators such as histamine and leukotrienes, were evaluated in several animal models. DS-4574 had dose-dependent inhibitory effects on IgE-mediated passive cutaneous anaphylaxis and the passive Arthus reaction in rats and the phase I response of Forssman antibody-induced bronchoconstriction. In contrast, this compound had no effect on the phase II response of Forssman antibody-induced bronchoconstriction in guinea pigs, the reverse cutaneous anaphylaxis in rats, complement-dependent hemolysis of sheep erythrocytes and the delayed-type hypersensitivity induced by methylated bovine serum albumin in mice. The results obtained in a double sensitization with two IgE antibodies suggested that DS-4574, as well as disodium cromoglycate, did not impair antigen-antibody combination but prevents the release of chemical mediators such as histamine. DS-4574 also had a weak inhibitory activity on carrageenin paw edema in rats, arachidonic acid ear edema in mice and adjuvant arthritis in rats. In addition, this compound inhibited increased vascular permeability in rat skin induced by leukotriene D4 and platelet activating factor-induced pleurisy in rats in a dose-dependent manner. These results indicate that DS-4574 inhibited type III allergic reactions and some inflammatory reactions. Therefore, DS-4574 could be useful in the treatment of allergic diseases such as asthma.

Animals↗
PubMed1992

Synthesis and antiallergy activity of [1,3,4]thiadiazolo[3,2-a]-1,2,3-triazolo[4,5-d]pyrimidin-9 (3H)-one derivatives. I.

A series of 6-substituted [1,3,4]thiadiazolo[3,2-a]-1,2,3-triazolo[4,5-d]pyrimidin-9(3H)-one derivatives 4a--z were synthesized from 5-substituted 1,3,4-thiadiazol-2-amines 5 by the following consecutive reactions: pyrimidine ring closure with bis(2,4,6-trichlorophenyl) malonate, nitration, chlorination, amination, hydrogenation and diazotization. The structure of 4 was confirmed by an alternate synthesis of 4, involving reaction of 5-substituted 2-azido-1,3,4-thiadiazole 13 with ethyl cyanoacetate, followed by the Dimroth rearrangement and ring closure. The antiallergic activities (anti-passive peritoneal anaphylaxis, anti-passive cutaneous anaphylaxis and anti-slow reacting substance of anaphylaxis activities) of the products were evaluated.

Anaphylaxis↗
PubMed1991

The effect of treatment with recombinant gamma-interferon on adjuvant-induced arthritis in rats.

We have investigated the effects of recombinant rat gamma-interferon (rIFN gamma) on adjuvant-induced arthritis (AA). Lewis rats, inoculated in the left hind-paw with adjuvant (day 0), were given 10(5) U/rat of rIFN gamma daily (days 0 to 20), subcutaneously and intramuscularly on alternate days. rIFN gamma suppressed the secondary phase of swelling of both hind-paw on and after day 18 without influencing the earlier phases, both primary and secondary, of swelling. rIFN gamma also reduced the hind-paw bone lesions, the degree of splenomegaly, and the increase in erythrocyte sedimentation rate and plasma fibrinogen. These results indicate a new aspect of the regulatory role of IFN gamma in chronic inflammation.

Animals↗