s- and p-wave pairings in the dilute electron gas: Superconductivity mediated by the Coulomb hole in the vicinity of the Wigner-crystal phase.
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Journal Article↗
Biomedical subjects
Y Takada
Publications and source records attributed to Y Takada.
Compressibility and spin susceptibility of the alkali metals in the effective-potential expansion method: Competition between many-body and band effects in charge and spin responses.
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Journal Article↗
[A study of the utility of the MR image for the diagnosis of thymic tumors--imaging and pathologic correlation].
MR imaging was performed in 25 patients with thymic tumors (five with non-invasive thymomas, 15 with invasive thymomas, and five with thymic carcinomas), and the MR imaging appearance was compared with the pathological findings. Non-invasive thymomas showed generally oval or round masses with well-defined margins and homogeneous intensity on T1- and T2-weighted images. Invasive thymomas showed a multinodular appearance in 79% (11/15) of cases, and an internodular difference in signal intensity (IDSI) in 64% (7/11) on T2-weighted images. It was considered that the IDSI on T2-weighted images correlated pathologically with the hemorrhagic and/or necrotic areas and hyalinization. The IDSI seemed to be a characteristic finding of invasive thymomas. The histological findings and MR imaging appearance of thymomas were compared. The predominantly epithelial type showed a low incidence of nodular appearance but showed marked IDSI on T2-weighted images. Therefore, it is more likely that the predominantly epithelial type induced more varied intratumoral changes than other types. Extension of thymic carcinomas was similar to that of invasive thymomas on MR imaging, but thymic carcinomas showed no definite nodular appearance. In conclusion, MR images in thymic tumors were useful for not only determining the morphology of the tumor but also the tissue characteristics. Therefore, MR imaging can be a useful modality to correlate with the histological findings and biological behavior of thymic tumors.
Adult↗
Effect of prostaglandin E1 on preservation injury of canine liver grafts preserved in UW solution.
This study investigated whether prostaglandin E1 (PGE1) could reduce hepatic injury to the liver graft caused by harvesting and 24-h preservation in University of Wisconsin (UW) solution in a canine model. The PGE1-treated group was intravenously administered 0.5 microgram/kg per minute of PGE1 for 30 min before harvesting, as well as a concentration of 1 mg/l PGE1 in the washout and UW solutions. In both the PGE1-treated and the control group, all recipients survived for 1 week or more after transplantation. Arterial ketone body ratio (AKBR) remained over 1.0 in the early postoperative period. The PGE1 group showed significant reductions in guanase, GOT, and LDH during the early postoperative period compared to the untreated control group. Histological examination disclosed partial mitochondrial swelling, hepatocyte vacuolation, and necrosis in the control group, while such abnormalities were rarely seen in the PGE1 group. These results suggest that PGE1 can effectively reduce hepatic injury to liver grafts preserved in UW solution prior to transplantation.
Adenosine↗
Characteristics of proton beams after field shaping at PMRC.
The proton irradiation control system was developed for cancer radiotherapy at the Proton Medical Research Center, with the extension of a beam line connected to a synchrotron at the High Energy Physics Laboratory. The initial energy of the 500 MeV proton beam supplied by the accelerator is degraded down to 243 MeV after passing through a graphite rod. In the control system, a proton beam is scattered to form a large field, its Bragg peak width is spread out, and its energy is degraded to the optimum value with a range covering tumour depth. The characteristics of the devices required for these procedures have been investigated from the viewpoint of the relationship between dose rate and field flatness, taking the setting-up geometry of these devices into consideration.
Humans↗
Demonstration of primary tracheobronchial amyloidosis by 99mTc-HMDP bone SPECT.
A case of primary tracheobronchial amyloidosis is reported. A 61-year-old man presented with a 2-year history of intermittent hemoptysis. Chest X-ray and CT scanning showed tracheobronchial thickening. Bronchoscopic examination revealed diffuse tracheobronchial narrowing, and tracheobronchial biopsy detected amyloid deposits. Both 99mTc-HMDP planar and SPECT images were obtained in this patient. Coronal SPECT images revealed more precisely that the activity was not in the thoracic cage but in the bilateral hilar region. Localization of the amyloid deposits could be better determined on SPECT images than on planar images.
Amyloidosis↗
Correlation between serotonergic measures in cerebrospinal fluid and blood of subhuman primate.
The relationship between the concentration of serotonin (5-hydroxytryptamine; 5-HT), its precursor; tryptophan (Trp) and the main metabolite 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF) and blood of monkey have been studied. 5-HT, Trp and 5-HIAA underwent circadian changes in both CSF and blood. Significant correlations were found between 5-HT, 5-HIAA and Trp in CSF and blood. The significance of these findings and their relationship to the use of peripheral serotonergic system as a functional model of the central nervous system are discussed.
Animals↗
Clinical results of fractionated proton therapy.
PURPOSE: Preliminary results of a multi-site Phase I-II clinical trial investigating the efficacy of high-energy proton beams in a wide variety of human malignancies are reported. METHODS AND MATERIALS: Since 1983 proton radiotherapy using 250 MeV proton beams produced by a booster synchrotron of the National Laboratory for High Energy Physics has been carried out at Proton Medical Research Center, University of Tsukuba. As of September 1990, a total of 147 patients received a partial or full treatment with proton beams with curative intent; 92 patients (63%) were treated with proton beams alone and 55 patients (37%) with combined photon and proton beams. There were 91 males and the mean age was 61.8 years old. The follow-up observation period ranged from 10 to 97 months. With regard to a total tumor dose, nearly 80% of patients received 70 Gy or more and 53% received 80 Gy or more. While dose-fractionations used depended upon tumor sites, the large majority of patients received substantially high radiation doses in terms of larger total doses (> 70 Gy) and larger fraction sizes (> 2.5 Gy) than those traditionally used. This fractionation regimen has been used because of limited availability of the accelerator or a shortage of machine time (27-30 weeks/year, 3-3.5 hr/day), and also by the expectation that the superior dose distribution possible with protons will permit administration of high radiation doses without increasing morbidities. In connection with this, we have determined the target volume by setting margins around the tumor boundary as practically small as possible, ranging from 5 to 10 mm. RESULTS AND CONCLUSIONS: The current trial has been based on a site and dose searching program, hence a wide variety of tumor sites including the aerodigestive organs has been treated. So far, our judgment is that proton therapy has proven of potential advantage in treatment of the lung, esophageal, liver, uterine cervix, prostate, and head and neck malignancies; and of possible value in treatment of high-grade gliomas, and gastric, urinary bladder, and pediatric tumors.
Adolescent↗
Short-term changes in lipid and protein metabolism in liver transplants from living-related donors.
The effects of liver transplantation involving living-related donors were investigated in 20 pediatric cases in terms of protein and lipid metabolism using the extent of cholesterol esterification and the levels of total cholesterol, lecithine-cholesterol acyltransferase, apolipoprotein A-I, cholinesterase, and rapid turnover proteins as parameters. Cholesterol esterification increased from preoperative values of 39% +/- 4% to 67% +/- 1% (mean +/- SEM, n = 17) at 3 weeks after liver transplantation in successful cases but decreased from the preoperative value of 45% +/- 10% to 26% +/- 6% (n = 3) at 3 weeks in unsuccessful cases. Cholinesterase, transferrin, and prealbumin levels remained low after 3 weeks even in successful cases. Patients who had partial liver transplantations from living-related donors showed rapid recovery of cholesterol esterification. However, patients with graft livers required an extensive period before normalization of protein metabolism occurred, indicating the necessity for long-term follow-up of recipient development.
Adolescent↗
Interaction of integrins alpha 3 beta 1 and alpha 2 beta 1: potential role in keratinocyte intercellular adhesion.
The colocalization of integrins alpha 2 beta 1 and alpha 3 beta 1 at intercellular contact sites of keratinocytes in culture and in epidermis suggests that these integrins may mediate intercellular adhesion (ICA). P1B5, an anti-alpha 3 beta 1 mAb previously reported to inhibit keratinocyte adhesion to epiligrin, was also found to induce ICA. Evidence that P1B5-induced ICA was mediated by alpha 2 beta 1 and alpha 3 beta 1 was obtained using both ICA assays and assays with purified, mAb-immobilized integrins. Selective binding of alpha 2 beta 1-coated beads to epidermal cells or plate-bound alpha 3 beta 1 was observed. This binding was inhibited by mAbs to integrin alpha 3, alpha 2, or beta 1 subunits and could be stimulated by P1B5. We also demonstrate a selective and inhibitable interaction between affinity-purified integrins alpha 2 beta 1 and alpha 3 beta 1. Finally, we show that expression of alpha 2 beta 1 by CHO fibroblasts results in the acquisition of collagen and alpha 3 beta 1 binding. Binding to both of these ligands is inhibited by P1H5, an anti-alpha 2 beta 1 specific mAb. Results of these in vitro experiments suggest that integrins alpha 2 beta 1 and alpha 3 beta 1 can interact and may do so to mediate ICA in vivo. Thus, alpha 3 beta 1 mediates keratinocyte adhesion to epiligrin and plays a second role in ICA via alpha 2 beta 1.
Animals↗
Distinct functions of integrin alpha and beta subunit cytoplasmic domains in cell spreading and formation of focal adhesions.
Integrin-mediated cell adhesion often results in cell spreading and the formation of focal adhesions. We exploited the capacity of recombinant human alpha IIb beta 3 integrin to endow heterologous cells with the ability to adhere and spread on fibrinogen to study the role of integrin cytoplasmic domains in initiation of cell spreading and focal adhesions. The same constructs were also used to analyze the role of the cytoplasmic domains in maintenance of the fidelity of the integrin repertoire at focal adhesions. Truncation mutants of the cytoplasmic domain of alpha IIb did not interfere with the ability of alpha IIb beta 3 to initiate cell spreading and form focal adhesions. Nevertheless, deletion of the alpha IIb cytoplasmic domain allowed indiscriminate recruitment of alpha IIb beta 3 to focal adhesions formed by other integrins. Truncation of the beta 3 subunit cytoplasmic domain abolished cell spreading mediated by alpha IIb beta 3 and also abrogated recruitment of alpha IIb beta 3 to focal adhesions. This truncation also dramatically impaired the ability of alpha IIb beta 3 to mediate the contraction of fibrin gels. In contrast, the beta 3 subunit cytoplasmic truncation did not reduce the fibrinogen binding affinity of alpha IIb beta 3. Thus, the integrin beta 3 subunit cytoplasmic domain is necessary and sufficient for initiation of cell spreading and focal adhesion formation. Further, the beta 3 cytoplasmic domain is required for the transmission of intracellular contractile forces to fibrin gels. The alpha subunit cytoplasmic domain maintains the fidelity of recruitment of the integrins to focal adhesions and thus regulates their repertoire of integrins.
Amino Acid Sequence↗
Arterial ketone body ratio as a predictor of donor liver viability in human liver transplantation.
The viability of the donor liver was assessed with regard to early postoperative survival in human liver transplantations from 40 brain-dead donors at Hannover Medical College and 13 living donors at Kyoto University by measuring the arterial ketone body ratio (AKBR). Of 40 grafts harvested from brain-dead patients in Hannover, 35 survived the first week after operation, but 5 developed initial nonfunction of the transplanted graft within the first week. The mean AKBR values were 1.11 +/- 0.11 for grafts that survived and 0.44 +/- 0.10 for grafts that failed (P < 0.01). The AKBR values of the 5 initially nonfunctioning cases were all below 0.7. Of 13 grafts harvested from the living donors in Kyoto, all survived the first week. The AKBR values of the donors were all above 1.0, with a mean value of 1.87 +/- 0.23. Among all 53 cases, the survival rate of the grafts with AKBR above 0.7 was significantly higher than that of the grafts with AKBR below 0.7 (100% vs. 62%, P < 0.01). No other donor parameters, including age, dose of dopamine administered, and clinical laboratory findings, were significantly related to differences in graft survival rates. AKBR is a useful index for the evaluation of donor liver viability. Grafts used from donors with AKBR of less than 0.7 have a significantly increased risk of early nonfunction. Grafts from donors with AKBR of greater than 1.0 have, in our experience, always been viable after transplantation.
Adult↗
Experience with FK506 in living-related liver transplantation.
The new immunosuppressive agent FK506 was used with steroids to treat 22 pediatric patients who received living-related partial liver transplantation. Seventeen recipients survived and 5 died between one and 16 months after transplantation. Three of the 5 patients who died had required intensive care preoperatively. Autopsy findings showed no evidence of rejection. There was no episode of rejection that required retransplantation in any of the patients. Liver allograft dysfunction, which was suspected to be a rejection response, was encountered in 2 recipients with ABO-nonidentical but compatible grafts. However, their clinical and biochemical findings were ameliorated upon steroid pulse therapy or upon augmented FK506 administration without additional potent immunosuppressive agents. Steroid treatment has been discontinued in all surviving patients at 1-9 months after transplantation. Infectious complications encountered in 9 patients included 2 bacterial, 5 viral, and 2 fungal infections. One recipient died of fungal pneumonia. Abnormal increase of serum creatinine level was confined to the complicated patients. Hypertension was a temporary adverse reaction in the early postoperative period, and only one patient needed an antihypertensive drug at 2 months after transplantation. Acute pancreatitis with hyperamylasemia was observed in one patient who was treated successfully with reduction of FK506 administration. Tremor was observed in 8 patients, itching in 4, insomnia in 2, and vomiting in one. Hirsutism, gingival hypertrophy, and lymphoma were not observed. FK506 was highly effective in living-related partial liver transplantation not only in terms of immunosuppressive potential but also because it produced fewer adverse effects.
Adolescent↗
Arterial ketone body ratio and glucose administration as an energy substrate in relation to changes in ketone body concentration after living-related liver transplantation in children.
Changes in the arterial ketone body ratio (AKBR [acetoacetate/3-hydroxybutyrate]), which reflect the redox state of the liver mitochondria (NAD+/NADH), as well as those in total ketone body concentration (TKB) and blood glucose level were studied in 30 living-related liver transplantations (LRLT) performed in pediatric patients at Kyoto University Hospital from June 1990 to January 1992. AKBR increased to over 1.0 within 6 hr after reperfusion of the graft in 11 cases (37%), within 12 hr in 7 (23%), on POD 1 in 8 (27%), and on POD 2 in the remaining 4 cases (13%). TKB significantly increased while AKBR remained below 0.7 (266 +/- 40 mumol/L), but it significantly decreased in accordance with the recovery of AKBR above 1.0 (61 +/- 6 mumol/L). This indicates the change in the predominant energy substrate for hepatic mitochondria from fatty acid to glucose during the AKBR recovery process. In 6 cases, the AKBR transiently decreased to below 1.0 after initial recovery concomitant with the fall in blood glucose level and the increase in TKB. However, the AKBR was rapidly restored to over 1.0 again immediately after the glucose administration was increased. This suggests that glucose administration to maintain blood glucose level between 150 and 250 mg/dl is essential for the AKBR recovery above 1.0 that accompanies the normalization of graft metabolic functions, and that, along with the postoperative minimal increase in serum enzymes and favorable outcome of the transplant with no incidence of a primary nonfunctioning graft, the prompt and successful recovery of AKBR reflects the expected high viability of the graft in our LRLT cases.
Adolescent↗
Genes encoding two isocitrate dehydrogenase isozymes of a psychrophilic bacterium, Vibrio sp. strain ABE-1.
The genes coding for two structurally different isocitrate dehydrogenase isozymes (IDH-I and IDH-II) of a psychrophilic bacterium, Vibrio sp. strain ABE-1, were cloned and sequenced. Open reading frames of the genes (icdI and icdII) are 1,248 and 2,229 bp in length, respectively. The amino acid sequences predicted from the open reading frames of icdI and icdII corresponded to the N-terminal amino acid sequences of the purified IDH-I and IDH-II, respectively. No homology was found between the deduced amino acid sequences of the isozymes; however, the IDH-I, a dimeric enzyme, had a high amino acid sequence identity (74.3%) to the Escherichia coli IDH. The deduced amino acid sequence of the IDH-II, a monomeric enzyme, was not related to any known sequence. However, the IDH-II had an amino acid sequence homologous to that of a cyanogen bromide-cleaved peptide containing a putative active-site methionyl residue of the monomeric IDH of Azotobacter vinelandii. The two genes (icdlI and icdII) were found to be tandemly located in the same orientation. Northern (RNA) blot analyses showed that the two genes are transcribed independently. Primer extension experiments located single transcriptional start sites 39 and 96 bp upstream of the start codons of icdI and icdII, respectively. The amount of icdI transcript but not icdII increased when Vibrio sp. strain ABE-1 cells were cultured in acetate minimal medium.
Amino Acid Sequence↗
Transposon mutagenesis by Tn4560 and applications with avermectin-producing Streptomyces avermitilis.
The Tn3-like Streptomyces transposon Tn4560 was used to mutagenize Streptomyces avermitilis, the producer of anthelmintic avermectins and the cell growth inhibitor oligomycin. Tn4560 transposed in this strain from a temperature-sensitive plasmid to the chromosome and from the chromosome to a plasmid with an apparent frequency of about 10(-4) to 10(-3) at both 30 and 39 degrees C. Auxotrophic and antibiotic nonproducing mutations were, however, obtained only with cultures that were kept at 37 or 39 degrees C. About 0.1% of the transposon inserts obtained at 39 degrees C caused auxotrophy or abolished antibiotic production. The sites of insertion into the S. avermitilis chromosome were mapped. Chromosomal DNA fragments containing Tn4560 insertions in antibiotic production genes were cloned onto a Streptomyces plasmid with temperature-sensitive replication and used to transport transposon mutations to other strains, using homologous recombination. This technique was used to construct an avermectin production strain that no longer makes the toxic oligomycin.
Anthelmintics↗
The physiology of the fibrinolytic system.
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Aging↗
Impaired fibrinolysis in hypertension and obesity due to high plasminogen activator inhibitor-1 level in plasma.
In order to elucidate the influence of the risk factors of coronary heart disease on the fibrinolytic activity, relationships between blood pressure, body mass index (BMI), plasma lipoprotein (a) (Lp(a)) level and the plasma levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) were analyzed in the subjects with mild hypertension. Systolic blood pressure showed a positive correlation with total PAI-1 and free PAI-1. Diastolic blood pressure showed no correlation with these proteins involved in the fibrinolytic system. BMI had a positive correlation with total PAI-1, free PAI-1 and euglobulin clot lysis time (ECLT). Plasma Lp(a) level showed correlation with neither blood pressure nor fibrinolytic parameters, but it showed weak negative correlation with body mass index (BMI). These results suggest that high blood pressure and obesity tend to increase free PAI-1 which reduces fibrinolytic activity. Lp(a), however, seems not to influence directly the fibrinolytic system but may work to decrease fibrinolytic activity only in conjunction with other risk factors. The effects of daily drinking of alcohol and smoking on the fibrinolytic system were also investigated in the present study and we obtained the results that habitual drinking increased plasma levels of both tPA and PAI-1 whereas smoking did not affect fibrinolytic activity. These results suggest that risk factors for coronary heart disease such as hypertension and obesity are closely related to the impaired fibrinolysis.
Adult↗