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Biomedical subjects

N Takeuchi

Publications and source records attributed to N Takeuchi.

At least 145 records · Page 8Linked to original sources
PubMed1993

Peripherally administered serotonin induces hyperglucagonemia in mice.

Peripherally administered serotonin (5-HT) induced a marked increase in the plasma glucagon level in mice. The hyperglucagonemic effects of 5-HT were completely antagonized by methysergide, ketanserin and ritanserin which have a high affinity for 5-HT2 receptors. However, the 5-HT3 receptor antagonist ICS 205-930 and MDL 72222 were without effect. These findings suggest that the activation of the peripheral 5-HT2 receptor induces the increase in plasma glucagon level and that these receptors may play a role in the release of glucagon.

Animals↗
PubMed1993

Actions of benzalkonium chloride as a potent depressant at the neuromuscular junction.

Benzalkonium chloride (BA), a positively charged surface active agent, applied (> 10 nM) in the superfusing solution, produced a concentration-dependent reduction in the amplitude of both evoked endplate potentials (EPPs) and spontaneous miniature EPPs of the frog. Voltage-clamped endplate currents (EPCs) and spontaneous miniature endplate currents (MEPCs) were also diminished in amplitude, in the presence of BA (50-140 nM), whereas their time-course and reversal potential were not obviously affected. No significant change due to the addition of 50 nM BA was observed in apparent properties of the ACh channel estimated from ACh-induced current fluctuations. In the relationship between the amplitude of ACh potentials and the net charge for iontophoretic pulses at a single junction, the principal pattern of action of BA (30-60 nM) appeared to be a parallel shift to the right. At concentrations greater than about 1 microM, BA slightly increased the resting input conductance of the non-synaptic muscle fibre membrane. It was suggested that this increase was attributable to a slight increase in Cl ion conductance of the non-synaptic membrane. These results indicate that BA effectively blocked neuromuscular transmission, acting as an ACh receptor antagonist at smaller concentrations and as a more potent blocker that acts through multiple sites at greater concentrations.

Acetylcholine↗
PubMed1993

Inhibition of homologous complement activation by the heat-stable antigen.

The murine heat-stable antigen (HSAg) is of particular interest due to its unique tissue distribution. HSAg is expressed on most thymocytes, bone marrow cells, immature B cells, and erythrocytes, but not on peripheral T and mature B cells. Although HSAg has been thought to be a differentiation antigen, its actual biological significance remains unknown except for the HSAg on antigen presenting cells. Recently, a new rat anti-HSAg mAb, R13, has been developed. Here it has been found that the mouse complement activation on mouse erythrocytes, but not the human, guinea pig or rabbit complement activations, was enhanced in the presence of the Fab fragment of R13. Affinity-purified HSAg derived from mouse erythrocytes could be passively incorporated into rabbit erythrocytes because of its molecular characteristic of glycosylphosphatidyl inositol-anchored protein. Mouse complement activation, but not guinea pig complement activation, was partially suppressed on the HSAg-incorporated rabbit erythrocytes. These findings suggest that HSAg has a homologous complement regulating activity.

Animals↗
PubMed1993

Membrane-associated lymphotoxin expression and functional analysis of lymphokine-activated killer cells derived from tumor-infiltrating lymphocytes.

The expression of a membrane-associated lymphotoxin molecule (mLT) on lymphokine-activated killer (LAK) cells obtained from 18 patients with malignant tumors and its role in the tumor cell killing mechanisms were investigated. LAK cells from tumor-infiltrating lymphocytes (TIL-LAK cells) were mainly composed of CD3-positive cells, whereas LAK cells from peripheral blood lymphocytes (PBL-LAK cells) were mainly composed of CD16- and CD56-positive cells. However, mLT was found to be expressed on TIL-LAK cells as well as PBL-LAK cells. The degree of mLT expression correlated with the killing activity of LAK cells towards L929 cells (r = 0.806, P < 0.01, n = 15), but not with that towards Daudi or K562 cells. Although the degree of mLT expression correlated with the amount of secreted lymphotoxin (LT) in the supernatant of LAK cell culture, the secreted LT itself could not account for the tumor cell killing activity of LAK cells. Polyclonal rabbit anti-LT antibody partially inhibited the killing activities of LAK cells towards L929 cells and this inhibition was found in the combination of autologous tumor cells and PBL-LAK cells. These findings suggest the possibility that the mLT-related cytotoxicity is involved in the tumor cell killing mechanisms of TIL-LAK cells as well as PBL-LAK cells.

Adult↗
PubMed1993

Interpretation of subtle interstitial lung abnormalities: conventional versus storage phosphor radiography.

To evaluate the reliability of storage phosphor radiography (SR) in diagnosis of subtle interstitial lung abnormalities, the differences among radiologists in interpreting conventional screen-film radiographs and full-size and minified SR images obtained in 80 patients were studied. Forty patients had subtle interstitial lung abnormalities and 40 had no lung abnormalities. Seven chest radiologists and seven residents evaluated the images by using a five-point presence of abnormality scale. Results were evaluated with receiver operating characteristic technique. For all observers, no significant differences were observed among the three image types. For the chest radiologists, significant differences were observed between conventional radiographs and the two SR formats (P < .01). Furthermore, perceptual accuracy was best with conventional radiographs evaluated by chest radiologists. Overall performance with SR and conventional radiography was identical for diagnosis of abnormalities, but detection performance was significantly dependent on observer experience (P < .01 for chest radiologists and P > .01 for residents). For chest radiologists, critically important information may be lost with commercially available SR.

Adolescent↗
PubMed1993

Focal organizing pneumonia: CT appearance.

PURPOSE: To clarify the computed tomographic (CT) features of focal organizing pneumonia. MATERIALS AND METHODS: The authors retrospectively studied CT scans of 18 patients with histologically proved focal organizing pneumonia. Chest radiographs in all 18 patients suggested bronchogenic carcinoma. RESULTS: Seventeen of the 18 lesions (94%) had an irregular margin, 10 (56%) had satellite lesions, nine (50%) had a pleural tag, and nine (50%) had an air bronchogram. The pneumonia could be classified into three types: Type A (n = 5) was a small round mass (pleural tag, n = 4). Type B (n = 7) was an oval mass with broad contact with the pleura (satellite lesions and convergence of peripheral vessels, n = 6). Type C (n = 6) was an oval mass along the bronchovascular bundle (satellite lesions, n = 3; pleural tag, n = 4). CONCLUSION: The CT features of focal organizing pneumonia show wide variation, and some type B and C lesions are suggestive of benign lesions. However, other lesions may be difficult to differentiate from bronchogenic carcinoma even with CT.

Adult↗
PubMed1993

Ultrastructural arrangement of collagen fibrils in the rat facial nerve.

We studied the collagen fibril arrangement in the connective tissue sheaths (epineurium, perineurium, and endoneurium) of the intratemporal and extra-temporal portion of the rat facial nerve by transmission electron microscopy after fixing the nerves with tannic acid, and by scanning electron microscopy after digesting cellular elements by sodium hydroxide treatment. These studies revealed that the epineurium consists of thick bundles of collagen fibrils and a coarse meshwork of collagen fibrils, the perineurium consists of a lacework sheet of bundles of collagen fibrils, and the endoneurium consists of a meshwork of fine collagen fibrils in the inner layer and of longitudinally oriented bundles of collagen fibrils in the outer layer. There was little difference in the three-dimensional organization of collagen fibrils between the extra-temporal segment and vertical and horizontal segments of the facial nerve. However, the facial nerve lost the epineurium and perineurium in the central portion of the horizontal segment near the geniculate ganglion and in the labyrinthine portion, i.e. the proximal portion of the intratemporal segment. In these segments, the endoneurium consisted of a meshwork of fine collagen fibrils.

Animals↗
PubMed1993

[The effects of the treatment for acute rejection with OKT3 monoclonal antibody treatment on the long-term results of cadaveric kidney transplantation].

Although the efficacy of OKT3 monoclonal antibody (OKT3) upon the steroid resistant rejection is well known, its beneficial effect on long-term result of kidney transplantation has not yet been well examined in Japan. A retrospective group study was performed to analyze the effect of OKT3 on the cadaver kidney allograft. Between September 1987 and October 1990, a total of 77 patients from four different hospitals were classified into 2 groups. Thirty-four patients from 2 hospitals were entered OKT3 therapy group and 43 patients from the other hospitals were entered steroid therapy group. Initial immunosuppression comprised low-dose cyclosporine (6 mg/kg), steroid and antilymphocyte globulin in both groups. In OKT3 therapy group, acute rejection episodes those were considered steroid resistant were observed in 7 patients. They were treated with OKT3 monoclonal antibody. Of the seven patients, six recovered normal renal function. The mild rejection in OKT3 therapy group was treated with high-dose steroid. Minimal follow-up was 2 years. The 2-year graft survival was 82.4% in OKT3 therapy group and 74.4% in steroid therapy group. Although the improvement on the 2 year graft survival with OKT3 treatment was 8%, the difference between two groups was not statistically significant.

Adolescent↗
PubMed1993

Sequential promotion of normal and leukemic hemopoiesis by recombinant human granulocyte colony-stimulating factor during the course of myelodysplastic syndrome.

A 48-year-old man developed refractory anemia with excess of blasts in transformation. Complete response was achieved by low-dose ara-C therapy, but he relapsed 15 months later, with pancytopenia and 13.0% myeloblasts in normocellular marrow. He was treated unsuccessfully with prednisolone, metenolone, and 1-alpha-hydroxyvitamin D3 for 8 weeks. He then developed life-threatening pneumonia and was treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF Filgrastim; 125 micrograms/day s.c.). The pneumonia resolved and, interestingly, he achieved a partial response, with normal blood cell counts and only a few dysmyelopoietic cells in the marrow. However, thrombocytopenia progressed when rhG-CSF administration was tapered. When the dose was increased again, leukemic blasts were found to proliferate. When rhG-CSF was discontinued, blasts rapidly decreased in the peripheral blood. Chromosomal analysis revealed a complex abnormality during the first relapse, a normal 46,XY karyotype during the partial response, and recurrence of the same complex abnormality during leukemic transformation. The stimulation index of marrow mononuclear cells cultured with rhG-CSF increased with disease progression. These findings suggest that rhG-CSF initially stimulated the selective proliferation of normal hemopoietic cells, but the evolution or selection of a leukemic clone responsive to rhG-CSF appears to have occurred subsequently.

Follow-Up Studies↗
PubMed1993

Mechanism of gravity-dependent atelectasis. Analysis by nonradioactive xenon-enhanced dynamic computed tomography.

RATIONALE AND OBJECTIVES: The physiologic mechanism of gravity-dependent atelectasis (GDA), a common finding identified during anesthesia, is not well understood. The purpose of this study was to determine whether an inherent reduction in alveolar volume or a reduction in alveolar ventilation is the more important causative factor for the development of GDA in an experimental animal model. METHODS: After uniform reduction of lung volume in ten rabbits by artificially induced pneumoperitoneum, dynamic inhalation computed tomography (CT) was performed using 50% nonradioactive xenon in oxygen. Time-CT attenuation value curves were fitted to an exponential function, CT value = a - b x e(-kt), and K value, which is proportional to the alveolar ventilation/alveolar volume ratio, was calculated by regression analysis. RESULTS: Gravity-dependent atelectasis occurred only in 5 of 10 rabbits. In this group, K values in the dorsal regions increased before the appearance of GDA. No significant change in K values in the ventral regions was observed. CONCLUSION: One mechanism of GDA may be a preferential reduction in alveolar volume without small airway collapse rather than alveolar volume loss secondary to decreased ventilation.

Animals↗
PubMed1993

[Evaluation and problems of ultracentrifugal technique for separation and analysis of serum lipoproteins: comparison with other analytical methods].

An ultracentrifugal technique for separating and analyzing serum lipoproteins was evaluated in comparison with analyses by electrophoresis using agarose-gel and polyacrylamide-gel. In general, the percent of pre beta- and beta-lipoproteins in electrophoresis was estimated higher than the percent of VLDL and LDL in ultracentrifugal method, while the percentage of alpha-lipoprotein in the former was estimated lower than that of HDL in the latter. In cases with abnormal lipoproteinemias, various discrepancies arose between the methods. For examples, pre beta- and beta-lipoproteins were estimated too high by the analyses with electrophoresis. The cholesterol content in HDL decreases in hypertriglyceridemia accompanied by an increase in triglyceride content. Therefore, when HDL cholesterol is determined by a polyanion method to assess the net HDL concentration in such cases, it is estimated to be low. Such errors are not only found in the determination of HDL cholesterol, but also in apoproteins in liver cirrhosis, because the composition of HDL apoprotein is markedly altered. Since the heterogeneity of lipoproteins separated by ultracentrifugation is characteristic in hereditary disorders of lipoproteins such as LCAT deficiency, the centrifugal technique is essential for lipoprotein analysis in such disorders. The disadvantages in ultracentrifugation are cross-contaminations among fractions, and removals of lipids and apoproteins from lipoprotein particles. Apo A-I and E proteins, and phospholipids were removed from the particles more rapidly than other components. From the results of repeated ultracentrifugation of HDL, 3% of apo A-I was estimated to be lost from the HDL during the centrifuge procedure.

Electrophoresis↗
PubMed1993

[An arch and ascending replacement for aortic arch dissection by "separate hypothermia" retrograde cerebral perfusion].

We have developed a new technique of cerebral perfusion during operations on the aortic arch. The concept of this technique is as follows. A retrograde cerebral perfusion provides a relative long time to perform the distal aortic repair, and simplifies the operation. To avoid the disadvantages by deep hypothermia, we perfused from SVC cannula with blood cooled at 10-15 degrees C, from femoral artery with blood cooled at 20-26 degrees C. A successful case using this method is as follows. A 68-year-old man was referred to our hospital for aortic arch dissection. He underwent an operation 4 weeks after onset. Graft replacement of ascending aorta and aortic arch was performed under this method. We perfused blood from SVC cannula at an internal jugular vein pressure of 30 cmH2O, and SVC perfusion flow was 600 cc/min. By this separate hypothermia perfusion, the nasopharyngeal temperature is maintained about 15 degrees C, the rectal temperature is maintained 22-24 degrees C. The duration of cerebral perfusion from SVC cannula was 125 min, but prolonged emergence from anesthesia and neurological deficit were not seen.

Aged↗
PubMed1993

Lipid transfer particle in the hemolymph of the American cockroach: evidence for its capacity to transfer hydrocarbons between lipophorin particles.

A lipid transfer particle (LTP) was isolated and purified from the hemolymph of the adult male American cockroach, Periplaneta americana, essentially according to the method previously developed for the purification of LTP from locust hemolymph. Fast protein liquid chromatography (FPLC) on a Mono Q column was used as the additional step to obtain pure LTP. The electron micrograph of purified cockroach LTP exhibited an unusual and asymmetric shape essentially similar to that reported for Manduca sexta LTP (Ryan et al. 1990. J. Lipid Res. 31:871-879). The cockroach LTP was also found to be basically similar to that of M. sexta and locust in terms of subunit structure and lipid composition, although there were significant differences particularly in the contents of hydrocarbons and diacylglycerol. A simple method for assaying LTP activity was developed, based on the finding that cockroach LTP can catalyze the transfer of labeled hydrocarbons (or diacylglycerol) from labeled high density lipophorin (HDLp) bound with a transfer membrane (Immoblion) to unlabeled HDLp dissolved in saline. This finding reveals that cockroach LTP has the capacity to transfer and/or exchange lipids between lipophorin particles with the same density. It was also demonstrated that cockroach LTP has the capacity to catalyze the transfer and/or exchange of hydrocarbons, in addition to diacylglycerol, between cockroach HDLp and locust low density lipophorin (LDLp).

Animals↗
PubMed1992

[Adverse reactions to low osmolar iodine contrast media (second report)].

From January to December 1990, we performed a prospective survey of adverse reactions to contrast media at two different institutes of Juntendo University. We collected a total of 4555 case sheets during the period. The radiological procedures we investigated were computed tomography, intravenous urography, arteriography, venography and myelography. Low osmolar iodine contrast medium was used almost exclusively (except for five cases). The overall incidence of adverse reactions was 7.0%, and there were no severe or fatal reactions. The incidence of adverse reactions was higher in females (8.5%) than in males (6.1%). The incidence of adverse reactions increased according to the dose of contrast medium, especially when more than 101 ml was injected. Intra-arterial injection caused adverse reactions most often, followed by regular intravenous injections, followed by bolus intravenous injections. Adverse reactions occurred most often during injection. The next occurred in 5 minutes after injection, and then, 5-10 minutes after the injection of contrast medium. The incidence of adverse reactions was higher in patients with a history of allergy or previous reactions. Allergic adverse reactions were observed at a higher frequency. Pretesting was performed in 56.7% of the cases.

Adolescent↗
PubMed1992

Purification of the murine heat-stable antigen from erythrocytes.

The rat anti-mouse erythrocyte (MRBC) monoclonal antibody (mAb), R13, has been developed. The MRBC membrane protein recognized by R13 (R13-Ag) can be purified by loading the butanol-extracted MRBC membrane solution on a R13-conjugated Cellulofine column in the presence of 0.1% CHAPS followed by elution with 1% CHAPS. The amino acid sequence of the affinity-purified R13-Ag corresponded to that predicted from the cDNA for the murine heat-stable antigen. It was revealed that the actual heat-stable antigen was composed of 27 amino acids.

Amino Acid Sequence↗
PubMed1992

Intestinal type alkaline phosphatase hyperphosphatasemia associated with liver cirrhosis.

Hyperphosphatasemia due to increased intestinal type serum alkaline phosphatase was noted in a 48-year-old male who had asymptomatic liver cirrhosis. The alkaline phosphatase activity in the serum was 828 U/l (our reference range in adults: 57-194 U/l), 94% of which was of the intestinal type as measured by an immunoprecipitation method. The intestinal component of alkaline phosphatase was separated into two major and some minor components using electrophoresis and isoelectrofocusing. One of the major components had similar mobility to that of a standard intestinal enzyme purified from adult intestine. The components were heat-labile and neuraminidase-resistant. Serial lectin affinity chromatography, however, indicated that sugar chain compositions of the alkaline phosphatase were different from those of the standard tissue intestinal enzyme. These results and further enzymological studies suggest that the patient's serum alkaline phosphatase basically consisted of several intestine-like isoforms.

Alkaline Phosphatase↗
PubMed1992

[Endobronchial intraluminal brachytherapy for patients with tracheobronchial carcinoma with high dose-rate 192-Iridium remote afterloading method].

Endobronchial intraluminal brachytherapy was conducted for 5 patients with tracheobronchial carcinoma using 192Iridium high dose-rate afterloading machine (microSelectron HDR) and guide tubes of 1.9 mm in outer diameter. Four patients with bronchial non-small cell carcinoma and one with tracheal adenocarcinoma were applied, and a dose of 6 Gy/Fr. at points 1 cm from the source once a week, and a cumulative dose of 18 Gy/3 Fr. was delivered. Guide tubes could be placed up to 3 tubes via the vocal airway, and new computer planning system could afford to calculate dose from independent lining of the source into optimization. This could be done with safety, and no remarkable acute side effects were observed attributable to this method.

Brachytherapy↗