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Biomedical subjects

K Tsuda

Publications and source records attributed to K Tsuda.

At least 127 records · Page 7Linked to original sources
PubMed1996

MHC class II restriction for T cell proliferative response to mite antigen.

BACKGROUND: We investigated the immunoreguratory role of the major histocompatibility complex in peripheral blood lymphocytes' proliferative response to mite antigen. METHOD: Peripheral blood lymphocytes of Japanese asthmatic patients were incubated with antigen obtained from Dermatophagoides pteronyssinus with a molecular weight of about 15,000, with and without 0.05 microgram/mL of monoclonal antibody against HLA class I or class II for seven days at 37 degrees C humidified in 5% CO2 and 95% air. RESULTS: High and low responders to the mite body antigen were found among the patients while there were no high responders among the healthy individuals tested. In the mite-sensitive asthmatic patients, CD4+ T cells were the population that responded to the antigen. Depletion of CD8+ T cells from the peripheral blood lymphocytes of mite-insensitive individuals caused high responsiveness to the antigen, indicative that the mite-specific CD4+ T cells controlled the high responsiveness and the antigen-specific CD8+ T cells, the low responsiveness. Anti-HLA-DR monoclonal antibody inhibited responsiveness. In contrast, anti-HLA-DQ monoclonal antibody produced high responsiveness in low responders to mite antigen. CONCLUSION: High T cell proliferative responsiveness to mite antigen was restricted by HLA-DR antigen through CD4+ T cells in high responders, whereas HLA-DQ antigen is a restriction antigen of low responsiveness through CD8+ T cells in low responders and non-atopic individuals.

Animals↗
PubMed1996

Scarpa's adipofascial flap for repair of wide scalp defects.

Scarpa's fascia is a prominent superficial fascial system of the body. It consists of a single membrane between the superficial fatty layer and deep fatty layer, and lies widely in the lower abdominal wall. We describe a case with a wide scalp defect resulting from a resection of a dermatofibrosarcoma, and reconstruction of the defect with Scarpa's adipofascial flap (i.e., a combined paraumbilical perforator-based adipofascial flap-groin adipofascial flap). The primary advantage of Scarpa's adipofascial flap for scalp defects is that (1) the donor site is most acceptable for a free flap with a minimal donor scar and minimal dysfunction; (2) even in cases in which large flaps are used, donor defects can be closed directly without skin grafting; (3) in the obese patient, this flap is preferable because of cosmetic improvement of the abdominal wall; (4) the donor area has so many perforators that an extended adipofascial flap can be obtained with a combination of these perforators; and (5) the flap may be nourished with one of several arteries, such as the superficial or deep inferior epigastric artery, or the superficial or deep circumflex iliac artery. The disadvantages of this flap are that the territory with a single artery may be smaller than a skin flap with the same artery and oversurfacing of the graft results in a poor cosmetic appearance. Scarpa's adipofascial flap is indicated when the defects are in an exposed area, especially in children, young patients, and females, and when this procedure is combined with a skin-expanding method in the secondary repair.

Adipose Tissue↗
PubMed1996

3DFT-flash MR imaging of pancreatic cancer with gadopentetate dimeglumine.

PURPOSE: We evaluated the usefulness of dynamic 3-dimensional Fourier transformation (3DFT) fast low angle shot (FLASH) MR imaging using gadopentetate dimeglumine (Gd-DTPA) to assess the extent of pancreatic cancer. MATERIAL AND METHODS: Breath-hold 3DFT-FLASH MR images (20/4; 25 degrees flip angle; 7 partitions; 3-5-mm slice thickness) were obtained before the ++administration of 0.1 mmol/kg of Gd-DTPA, just after (early phase), and 1 and 2 min (late phases) after in 14 patients with pancreatic cancer. All patients underwent surgical removal or laparotomy. We compared the findings of T1-, T2-, and postcontrast T1-weighted spin-echo (conventional SE) and 3DFT-FLASH imaging with histologic or surgical findings. RESULTS: Dynamic MR images could delineate the pancreatic tumors more clearly than the conventional SE images, and were useful for diagnosing vessel invasion. The contrast-to-noise ratio between the pancreatic cancer and the surrounding pancreatic parenchyma was significantly higher with the dynamic 3DFT-FLASH image than with the conventional SE images (p<0.01). CONCLUSION: Dynamic 3DFT-FLASH MR imaging with Gd-DTPA is useful in delineating and evaluating the extent of pancreatic cancer.

Adult↗
PubMed1996

MR evaluation of mediopatellar plica.

PURPOSE: Evaluation of the usefulness of MR imaging for diagnosing mediopatellar plica (MP) of the knee joint. MATERIAL AND METHODS: We prospectively examined MR images of 40 knee joints in 30 patients with symptoms. The pulse sequences were SE T1-weighted images (600/26 ms), T2-weighted images (1800/70), and FLASH images (320/15/flip angle 90 degrees). When a low-intensity band was found above the medial condyle of the femur on T1-weighted and T2-weighted MR images, we defined it as MP. We compared these MR findings with arthroscopic findings, including the SAKAKIBARA classification of MP. RESULTS: In 29 of the 40 knee joints in which MP was arthroscopically found, 27 were correctly diagnosed as having MP on MR. In the remaining 11 without MP, 9 were correctly diagnosed by MR. CONCLUSION: MR images are useful not only for detecting MP but also for evaluating its extension. Our results suggest that MR imaging is useful as a screening method for detecting MP before arthroscopy.

Adolescent↗
PubMed1996

CT and MR imaging of abdominal liposarcoma.

OBJECTIVE: CT and MR images were reviewed to correlate the histologic subtypes of abdominal liposarcoma with the radiologic findings. SUBJECTS AND METHODS: Ten patients with liposarcoma who underwent CT or MR imaging before surgery were included in this study. CT and MR imaging findings for these patients were compared retrospectively with histologic findings. RESULTS: Major histologic subtypes found in our group of patients were five well-differentiated, three myxoid, one pleomorphic, and one round-cell liposarcomas. The well-differentiated subtype consisted of lipoma-like and/or sclerosing components. The predominant attenuation and signal intensity characteristics of the lipoma-like components on CT and MR images resembled those of fat, whereas the predominant attenuation and signal intensity characteristics of the sclerosing components resembled those of muscle. The myxoid subtype showed, on unenhanced images, predominant attenuation and signal intensity characteristics that resembled those of water; on contrast-enhanced images, this subtype showed gradual reticular enhancement. The appearance of the round-cell and pleomorphic subtypes was that of heterogeneous, nonfatty tumors. Their characteristics were indistinguishable from those of other malignant soft-tissue masses. CONCLUSION: Each histologic subtype of abdominal liposarcoma showed different CT attenuation or MR imaging signal intensity characteristics. A clear understanding of these findings should prove helpful in the diagnosis of liposarcoma.

Abdominal Neoplasms↗
PubMed1996

Identification of two missense mutations in the GIP receptor gene: a functional study and association analysis with NIDDM: no evidence of association with Japanese NIDDM subjects.

Gastric inhibitory polypeptide (GIP) potently stimulates insulin secretion from pancreatic islets in the presence of glucose as an incretin. Because the insulinotropic effect of GIP is reduced in NIDDM, it should be clarified whether defects in the GIP receptor gene contribute to the impaired insulin secretion in NIDDM. Using genomic DNA samples from Japanese NIDDM and non-NIDDM subjects, we have investigated the entire coding region of the GIP receptor gene by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP). We have identified two missense mutations, Gly198-->Cys (Gly198Cys) in exon 7 and Glu354-->Gln (Glu354Gln) in exon 12. Investigation of the function of GIP receptor with either of these mutations reveals a half-maximal stimulation value of GIP-induced cAMP response in Chinese hamster ovary cells expressing the GIP receptor with Gly198Cys of 6.3 +/- 1.2 x 10(-10) mol/l (n = 3), which was considerably higher than that of the normal GIP receptor, 9.4 +/- 3.8 x 10(-12) mol/l GIP (n = 3), whereas that of the GIP receptor with Glu354Gln was not significantly different from that of the normal GIP receptor. To assess the possible role of the GIP receptor gene in genetic susceptibility to NIDDM, we have examined the allelic frequencies of Gly198Cys and Glu354Gln in NIDDM and control subjects. Association studies show no relationship between NIDDM and either of the two mutations.

Alleles↗
PubMed1996

[Obstruction of the true lumen by retrograde perfusion during repair of DeBakey type I aortic dissection: a case report].

Retrograde femoral perfusion is often used during the repair of DeBakey type I aortic dissections, however, it may cause serious ischemic damage of vital organs even though the arterial cannula is properly placed. A 58-year-old woman with chest pain was admitted to our hospital. She was operated on urgently because chest computed tomograms revealed that she suffered from a DeBakey type I aortic dissection. A ringed graft, 22 mm in diameter, was implanted into the ascending aorta using retrograde perfusion through the right femoral artery. Following the removal of the aortic cross-clamp and rewarming, the prosthetic graft remained flaccid and the heart failed to resume beating. We speculated that retrograde femoral perfusion caused the true lumen obstruction while distending the false lumen. This resulted in blocking reperfusion of the coronary arteries. After antegrade perfusion was initiated through an 8 mm Dacron graft which was anastmosed to the ringed graft, the heart soon resumed beating. During the repair of DeBakey type I aortic dissections, this serious complication should be anticipated. If it occurs, retrograde femoral perfusion must be exchanged for antegrade aortic perfusion before irreversible changes occur.

Aortic Dissection↗
PubMed1996

[Blood flow measurement of portal vein with fast cine phase contrast MR imaging under breath-holding].

Flow measurements of the right portal vein were performed in seven healthy volunteers with the segmented k-space fast gradient-echo phase-contrast (fcard-PC) sequence under breath-holding. The mean velocity and the flow rate of the right portal vein at maximal expiration, 14.3 +/- 4.4cm/sec and 457 +/- 218 ml/min, were significantly greater (p < 0.01) than those at maximal inspiration: 11.8 +/- 3.8cm/sec (mean +/- SD) and 364 +/- 191ml/min, respectively. Fcard-PC enabled flow measurements to be obtained under breath-holding. Using this technique, we demonstrated portal venous flow changes according to respiratory phase.

Adult↗
PubMed1995

Enzymatic and chemical cleavage of the core light-harvesting polypeptides of photosynthetic bacteria: determination of the minimal polypeptide size and structure required for subunit and light-harvesting complex formation.

To ascertain the minimal structural requirements for formation of the subunit and core light-harvesting complex (LH1), the alpha- and beta-polypeptides of the LH1 from three purple photosynthetic bacteria were enzymatically or chemically truncated or modified. These polypeptides were then used in reconstitution experiments with bacteriochlorophyll a (BChla), and the formation of subunit and LH1 complexes was evaluated using absorbance and circular dichroism spectroscopies. Truncation or modification outside of the conserved core sequence region of the polypeptides had no effect on subunit or LH1 formation. However, the extent of formation and stability of the subunit and LH1 decreased as the polypeptide was shortened inside the core region within the N-terminal domain. This behavior was suggested to be due to the loss of potential ion-pairing and/or hydrogen-bonding interactions between the polypeptides. While the spectroscopic properties of the subunit complexes generated using truncated polypeptides were analogous to those obtained using native polypeptides, in some cases the resulting LH1 complex absorption was blue-shifted relative to the control. Thus, truncation within the N-terminal domain may have long-range effects on the immediate BChla binding environment, since the putative BChla binding site resides near the C-terminal end of the polypeptides. It was also demonstrated that the His located within the membrane-spanning domain on the N-terminal end of the beta-polypeptide is not participating in ligation of the BChla in the reconstituted subunit and therefore probably not in LH1.

Amino Acid Sequence↗
PubMed1995

Effects of Troglitazone (CS-045) on insulin secretion in isolated rat pancreatic islets and HIT cells: an insulinotropic mechanism distinct from glibenclamide.

In order to elucidate the direct effects of (+/-)-5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-yl-methoxy) benzyl]-2,4-thiazolidinedione (Troglitazone), a newly-developed oral hypoglycaemic agent, on pancreatic beta-cell function, in vitro investigation of isolated rat pancreatic islets and a hamster beta-cell line (HIT cell) were performed. Troglitazone stimulates both glucose, and glibenclamide-induced insulin release at a concentration of 10(-6) mol/l in these cells but, conversely, inhibits insulin secretion at 10(-4) mol/l. Glucose uptake in HIT cells is similarly enhanced by 10(-6) mol/l Troglitazone, but is reduced in the presence of 10(-4) mol/l Troglitazone. However, a quantitative immunoblot analysis with a specific antibody for GLUT 2 glucose transporter revealed no significant change in GLUT 2 protein in HIT cells with 10(-6) mol/l Troglitazone. Specific binding of [3H]-glibenclamide to beta-cell membranes is replaced by Troglitazone in a non-competitive manner, but 10(-6) mol/l Troglitazone failed to eliminate ATP-sensitive K++ channel activity. These results suggest that Troglitazone has a putative non-competitive binding site at, or in the vicinity of, the sulphonylurea receptor in rat pancreatic islets and HIT cells and that the dual effect of Troglitazone on insulin secretory capacity is mediated through the modulation of glucose transport activity, possibly due to the modification of intrinsic activity in glucose transporter in pancreatic beta cells by this novel agent.

ATP-Binding Cassette Transporters↗
PubMed1995

Sodium ions attenuate the inhibitory effects of neuropeptide Y on norepinephrine release in rat hypothalamus.

Neuropeptide Y (NPY) has a wide and specific distribution both in the central and peripheral nervous systems. In the present study, we have investigated the effects of NPY on norepinephrine release in rat hypothalamus, and further examined the interaction of NPY with alpha 2-adrenergic receptors, as well as the influence of sodium ions on the modulation of norepinephrine release. In an in vitro study, NPY significantly inhibited the stimulation-evoked norepinephrine release from hypothalamic slices in a dose-dependent manner. The alpha 2-adrenergic receptor agonist, UK 14,304, also reduced the stimulation-evoked norepinephrine release. A low concentration of NPY, which had no effects on its own, significantly potentiated the inhibitory effect of UK 14,304 on the stimulation-evoked [3H]norepinephrine release. The blockade of alpha 2-adrenergic receptors by RX 781094 diminished the inhibitory effects of NPY on norepinephrine release. Pretreatment of slices with pertussis toxin (a potent inhibitor of the Gi-proteins) significantly attenuated the suppressive effects of NPY and UK 14,304 on norepinephrine release. When the sodium concentration of the perfusion medium was increased, the inhibitory effects of NPY and UK 14,304 on norepinephrine release were significantly reduced. These results show that NPY might inhibit norepinephrine release that is partially mediated by alpha 2-adrenergic receptors and the pertussis toxin-sensitive Gi-proteins in rat hypothalamus. Moreover, less suppressive effects of NPY and UK 14,304 on norepinephrine release in the presence of excess sodium ions suggest that sodium ions might actively participate in regulating the NPY and alpha 2-adrenergic receptor mediated functions in the central nervous system.

Adrenergic alpha-Agonists↗
PubMed1995

The radial artery perforator-based adipofascial flap for dorsal hand coverage.

The radial artery perforator-based adipofascial flap seems to be suitable for resurfacing defects on the dorsal hand. This flap is classified as one of the distally based intertendinous septocutaneous flaps, which are supplied by the dorsal superficial branch of the radial artery. The advantages of this flap are (1) surgery is minimal, of short duration, and associated with minimal donor scarring; (2) the perforator of the flap encompasses a wide and long territory of adipofascial tissue; (3) there is no postoperative functional limitation; (4) freedom of arm movement allows better control of postoperative edema, early physiotherapy, and mobilization; (5) soft-tissue coverage actively contributes to the vascularity of the hand; and (6) the donor forearm cutaneous veins and cutaneous nerves can be preserved.

Adult↗
PubMed1995

Effects of captopril on [3H]-norepinephrine release in rat central nervous system.

1. The present study was performed to investigate the effects of captopril (an angiotensin converting enzyme inhibitor, ACE-I) on noradrenergic transmission in the rat central nervous system. 2. Slices of rat hypothalamus and medulla oblongata were prepared and prelabelled with [3H]-norepinephrine. Slices were continuously superfused with Krebs-Ringer solution, and electrical stimulation (1 Hz) was performed. 3. Captopril significantly inhibited the stimulation-evoked [3H]-norepinephrine release from rat hypothalamic slices in a dose-dependent manner (S2/S1 ratio: control 0.904 +/- 0.025, n = 6, captopril 1 x 10(-5) mol/L 0.617 +/- 0.043, n = 6, P < 0.05, captopril 5 x 10(-5) mol/L 0.547 +/- 0.037, n = 6, P < 0.05). However, the basal release of [3H]-norepinephrine was not affected by captopril. 4. Captopril also reduced the stimulation-evoked [3H]-norepinephrine release in the medulla oblongata (S2/S1 ratio: control 0.878 +/- 0.018, n = 6, captopril 3.3 x 10(-5) mol/L 0.624 +/- 0.046, n = 6, P < 0.05). 5. These results show that captopril might inhibit the stimulation-evoked norepinephrine release in rat hypothalamus and medulla oblongata. Although the precise mechanisms underlying the neurosuppressive effect of captopril are still uncertain, the finding suggests that the inhibition of noradrenergic transmission might be related to the central action of the ACE-I.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

Spin-labelling study of biomembranes in spontaneously hypertensive rats: calcium- and calmodulin-dependent regulation.

1. The present study was performed to investigate alterations in membrane characteristics of spontaneously hypertensive rats (SHR) by using an electron paramagnetic resonance (EPR) and spin-labelling methods. 2. Washed erythrocytes from SHR were examined and compared with erythrocytes from age-matched normotensive Wistar-Kyoto (WKY) rats. 3. The values of outer hyperfine splitting (2T' 11) and that of the order parameter (S) obtained from EPR spectra for a spin label agent (5-nitroxide stearate) were significantly higher in the erythrocytes of SHR than in those of WKY rats. 4. When calcium (Ca2+) was loaded to erythrocytes with a Ca2+ ionophore (A 23187), the order parameter (S) of the EPR spectra showed a greater increase in SHR than in WKY rats. Furthermore, the Ca2+ -induced change in the order parameter (S) of SHR was significantly antagonized by pretreatment of the Ca2+ antagonists (verapamil, diltiazem) and a calmodulin antagonist (W-7). 5. The results show that the erythrocyte membranes of SHR tolerated different spin motions from those of normotensive WKY rats in the EPR study, which might be associated with the idea that the membrane fluidity might be lower in SHR. Furthermore, the data suggest that Ca2+ -calmodulin antagonists may ameliorate the Ca2+ -induced changes in membrane functions in hypertension.

Animals↗
PubMed1995

Synergistic effects of Bay K 8644 and bradykinin on norepinephrine release in the hypothalamus of spontaneously hypertensive rats.

1. In the present study, we examined the effects of Bay K 8644, a dihydropyridine (DHP)-sensitive Ca2+ channel agonist, and bradykinin on norepinephrine release in the hypothalamus of spontaneously hypertensive rats (SHR). 2. In the preliminary studies using Sprague-Dawley rats, Bay K 8644 by itself had no significant effects on the stimulation-evoked [3H]-norepinephrine release from hypothalamic slices. Bradykinin increased the stimulation-evoked [3H]-norepinephrine release in a dose-related fashion. The facilitatory effects of bradykinin on norepinephrine release were potentiated by Bay K 8644. 3. In SHR, Bay K 8644 significantly increased the stimulation-evoked norepinephrine release from hypothalamic slices. However, exposure of slices to Bay K 8644 caused no significant effects on norepinephrine release in Wistar-Kyoto (WKY) rats. The effects of Bay K 8644 in combination with bradykinin on the stimulation-evoked norepinephrine release were also greater in SHR than in WKY rats. 4. These results demonstrate that Bay K 8644 significantly potentiated the facilitatory effects of bradykinin on norepinephrine release in rat hypothalamus. The finding indicates a possible interaction of bradykinin with DHP-sensitive Ca2+ channels in the central nervous system. Furthermore, the pronounced effects of Bay K 8644 and bradykinin in SHR suggest that bradykinin-related Ca2+ channels might have a role in the regulation of norepinephrine release in the hypothalamus of SHR.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗