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Biomedical subjects

H Maeda

Publications and source records attributed to H Maeda.

At least 631 records · Page 35Linked to original sources
PubMed1994

[In vivo characteristics of IBZM in rat brains: an agent for quantitative SPECT imaging of D2 dopamine receptors--a basis for semiquantitative measurement of the receptor density using equilibrium analysis].

To establish a basis for semiquantitative SPECT measurements of the D2 dopamine receptor density using equilibrium analysis, we evaluated in vivo kinetic properties of 125I-IBZM in rat brains. We measured percent uptakes (% dose/g) of 125I-IBZM in the striatum, frontal cortex, and cerebellum. We made these regional measurements at 15, 30, 45, 60, 90, and 120 minutes after injection, respectively. The specific striatal uptake, which is the uptake difference between striatum and frontal cortex or cerebellum, showed a transient equilibrium phase at 60 min. Theoretically, with these 'reversible' D2 receptor binding ligands, the tracer-uptake ratio of the striatum-to-frontal cortex or cerebellum during the equilibrium phase provides an estimate of binding potential (Bound/Free = Bmax/Kd). Our experiment showed that these ratio increased with time after bolus injection of the tracer. Striatum to frontal cortex or cerebellum ratios which were calculated with pooled data (n = 12) at 60 minutes in equilibrium phase showed nearly constant values (C.V. = 12.3% and 13.5%, respectively). Although measuring the striatum to frontal cortex or cerebellum ratios near equilibrium phase by bolus injection of the tracer which are widely used in human SPECT study could not exactly signify the binding potential, those ratios at fixed time after injection would be reliable for semiquantitative index.

Animals↗
PubMed1994

[A resected case of pulmonary plasma cell granuloma infiltrating the pericardium].

The patient was a 66-year-old man. An abnormal mass on his chest X-ray was pointed out during a regular check-up in November 1991. He was admitted to our hospital with the chief complaint of productive cough in January 1992. With the diagnosis of lung cancer, right middle and lower lobectomy with lymph node resection and partial resection of the pericardium was carried out. The pathological examination revealed pulmonary plasma cell granuloma infiltrating the pericardium. Postoperative course was uneventful. No recurrence was seen 17 months after operation. As pulmonary plasma cell granuloma is histologically benign, this was a very rare case with extra-pulmonary extension. Up to present, only 8 cases including this case has been reported in the literature. We reviewed these 8 cases.

Aged↗
PubMed1994

Possible mechanism of vascular damage in pre-eclampsia.

To clarify the pathophysiological changes of pre-eclampsia, we investigated the injurious effect of sera from women with pre-eclampsia on cultured endothelial cells, vascular smooth muscle cells and fibroblasts. We obtained serum samples from 32 Japanese women, including 10 healthy nonpregnant women, 12 normal pregnant women and 10 women with pre-eclampsia. Cell injury was measured by the release of radiolabelled chromium from the cells into the culture medium. The mean values +/- SD of percentage chromium release from endothelial cells in normal nonpregnant, normal pregnant and pre-eclamptic subjects were 8.5 +/- 2.4, 8.8 +/- 2.1 and 19.7 +/- 3.6%, respectively. Sera from women with pre-eclampsia demonstrated significantly greater endothelial cell injury than did sera from normal pregnant and nonpregnant subjects. However, normal pregnant and pre-eclamptic subjects did not differ with respect to both vascular smooth muscle cell injury and fibroblast injury. These results indicate that a serum cytotoxic to endothelial cells is present in pre-eclampsia and that this activity has a cellular specificity for endothelial cells.

Adult↗
PubMed1994

[In vivo characteristics of IBZM in rat brains: an agent for quantitative SPECT imaging of dopamine D2 receptors. Preparation of 125I-IBZM and its biodistribution and kinetic properties].

123I-(S)-(-)-3-iodo-2-hydroxy-6-methoxy-N-[(1-ethyl-2-pyrrolidinyl) methyl]-benzamide (IBZM) is a CNS dopamine D2 receptor imaging agent for SPECT and has already been used clinically in the United States, Canada and Europe. However, methods of quantitative SPECT measurement of the D2 receptor density have not been well established. We performed in vivo biodistribution studies of 125I-IBZM in rat brains as the first step toward establishment of a basis for quantitative SPECT imaging of D2 receptors in humans. 125I-IBZM was prepared by the chloramine-T method. Radiochemical yields were 80 to 90% and radiochemical purity was 94.7% on day 81 after labeling. At 10, 30, 60 and 120 min after injection of the radiopharmaceutical, the percent uptakes (% dose/g) in the rat striatum were 2.9, 1.9, 1.7 and 1.0, respectively. These kinetic data were considered suitable for SPECT imagings. Pretreatment with haloperidol (1 mg/kg) blocked specific striatal uptake and there was a significant reduction in the uptake to 40.9% of the unblocked uptake at 60 min after injection (p = 0.006). The regional IBZM uptake ratio of striatum-to-cerebellum increased steadily from 1.7 at 10 min to 5.7 at 120 min. This suggests that SPECT imaging must be done during fixed time after tracer injection for the semiquantitative ratio to be meaningful.

Animals↗
PubMed1994

[Surgical treatment of supravalvular aortic stenosis].

In the last 14 years, 7 consecutive patients with supravalvular aortic stenosis (SVAS) underwent surgical treatment for SVAS and/or for associated lesions. There were 5 male and 2 female patients ranging in age from 3 months to 12 years. Six of them had associated other cardiac anomalies; two had severe multiple peripheral pulmonary stenoses (PPS) and one each had ventricular septal defect (VSD), valvular pulmonary stenosis, coarctation of aorta with patent ductus arteriosus (PDA), total anomalous pulmonary venous return (TAPVR) with pulmonary branch stenosis, PPS and left lower pulmonary venous obstruction. The type of SVAS were localized in all and 5 of them underwent successful surgical repair of SVAS (3 with extended aortoplasty and 2 with patch aortoplasty). In 2 patients with VSD or valvular pulmonary stenosis, associated cardiac anomalies and SVAS were repaired simultaneously. Four patients had undergone previous operations, which included repair of severe multiple PPS by extended peripheral pulmonary arterioplasty (case 4, 6), repair of coarctation of aorta and division of PDA (case 5), repair of TAPVR (Ia + IIa) and pulmonary branch stenosis (case 7). There was no operative death and one patient died late postoperatively (case 7) due to right heart failure in a follow up period of 3 to 14 years. In conclusion, it is important to select the appropriate surgical treatment according to the location and the severity of associated other cardiac anomalies as well as the severity of SVAS, and extended peripheral pulmonary arterioplasty is considered to be a recommended method for the relief of severe multiple PPS associated with SVAS.

Aorta↗
PubMed1994

Pulmonary miliary tuberculosis and T-cell abnormalities in a severe combined immunodeficient patient reconstituted with haploidentical bone marrow transplantation.

We report the development of miliary tuberculosis in a 7-year-old boy with severe combined immunodeficiency (SCID), whose immune system had been only partially reconstituted by haploidentical bone marrow transplantation. Although alpha beta and gamma delta T cells were of donor origin, alpha beta T cells in this patient showed defective interleukin-2 (IL-2) production, impaired IL-2 responsiveness and decreased cytolytic activity. However, gamma delta T cells could exhibit enough cytolytic activity after incubation with IL-2. Despite the presence of disseminated infection, C-reactive protein (CRP) remained negative. IL-2 therapy aggravated the disseminated tuberculosis though gamma delta T cells were supposed to be activated, and concurrently CRP became positive. These findings suggest that gamma delta T cells have no more than limited immunological roles in mycobacterium tuberculosis infection.

Bone Marrow Transplantation↗
PubMed1994

[SMANCS/lipiodol].

SMANCS is the first commercially available polymer conjugated drug invented by the author, in which the protein antitumor agent neocarzinostatin is conjugated with two short chains of poly(styrene-comaleic acid) half-butylate. It exhibits the highest tumor/blood ratio (> 1,000) when injected arterially as an oily formulation in Lipiodol (SMANCS/Lipiodol). In addition, SMANCS/Lipiodol can give very high tumor contrasting image under X-ray (e.g., CT-scan), and thus the optimal dosing regimen can be determined and offers a diagnostic advantage. Phase I/II study of SMANCS was initiated in 1989 and it was approved by the Japanese Government in the fall of 1993 for the treatment of hepatoma. Exploitation of its application for other tumors such as renal cell cancer and pleural/ascitic carcinomatosis is anticipated. The response rate of Grad IV Lipiodol retention is 48.5% at 4 months; and those of 6 and 12 months are 50% and 90%, respectively. The major side effect is fever, which is only transitory, and no bone-marrow suppression, renal or hepatic toxicity were observed.

Animals↗
PubMed1993

Protein-tyrosine kinase p72syk is activated by thromboxane A2 mimetic U44069 in platelets.

We show that p72syk is rapidly activated following the stimulation of thromboxane A2 mimetics, U44069 and STA2 in porcine platelets. The activity of p72syk reached a maximum at 10 s and decreased to a basal level within 60 s after 1 microM U44069 stimulation. This activation was enhanced in a dose-dependent manner and completely canceled by the pretreatment of platelet suspension with ONO3708, a specific antagonist of thromboxane A2. Pretreatment of platelets with aspirin as well as apyrase did not affect the activation of p72syk. When both extra- and intra-cellular Ca2+ were depleted, the activation of p72syk was still persistent; in contrast, the deactivation process was completely abrogated even at 120 s after U44069 stimulation. These results suggest that p72syk is a responsible enzyme to the protein-tyrosine phosphorylation events, and that p72syk functions mainly before Ca2+ recruitment in thromboxane A2-stimulated platelets.

Animals↗
PubMed1993

Vascular permeability enhancing activity of Porphyromonas gingivalis protease in guinea pigs.

Porphyromonas gingivalis protease, which had been isolated from a culture supernatant, caused vascular permeability enhancement in a dose-dependent manner when injected into guinea pig skin. The permeability-enhancing reaction caused by the protease was not affected by treatment with antihistamine, but was greatly augmented by simultaneous injection of a kinin potentiator, carboxypeptidase N inhibitor. However, the reaction was inhibited by soybean trypsin inhibitor or alpha 2-antiplasmin, although both of these inhibitors could not inhibit P. gingivalis protease at all by themselves. A bradykinin-degrading enzyme, carboxypeptidase B, weakened this vascular reaction. Results described indicate that the permeability-enhancing reaction induced by the protease is caused by activation, of the kallikrein-kinin cascade in the tissue.

Animals↗
PubMed1993

Activation of protein-tyrosine kinase p72syk with concanavalin A in polymorphonuclear neutrophils.

We studied the abundance, subcellular distribution of a non-receptor protein-tyrosine kinase p72syk (Taniguchi, T., Kobayashi, T., Kondo, J., Takahashi, K., Nakamura, H., Suzuki, J., Nagai, K., Yamada, T., Nakamura, S., and Yamamura, H. (1991) J. Biol. Chem. 266, 15790-15796) in porcine polymorphonuclear neutrophils and the activation upon the stimulation with concanavalin A. The abundance was about 0.1% of total proteins and mainly distributed in the particulate fraction. Upon concanavalin A stimulation, the activity of p72syk increased within 30 s, attained to the maximum level at 1 min, and then returned to the basal level within 6 min. This activation was observed in a dose-dependent manner and abrogated by simultaneous addition of methyl alpha-mannopyranoside. When both extra- and intracellular Ca2+ were depleted, the activation of p72syk was still persistent; in contrast, the deactivation process was completely abrogated even at 6 min after stimulation. The replenishment of Ca2+ in the presence of A23187 resulted in a similar deactivation pattern as seen in the Ca(2+)-rich condition. In addition, genistein and herbimycin A, potent protein-tyrosine-kinase inhibitors, were capable of reducing concanavalin A-evoked p72syk activation and Ca2+ mobilization as well as the aggregation and lysozyme release. Furthermore, A23187-induced Ca2+ accumulation in inhibitor-treated cells resulted in the restoration of those cellular responses. These lines of evidence suggest that p72syk is activated with concanavalin A in a Ca(2+)-independent manner, participating in a mechanism of Ca2+ recruitment, and negatively regulated by a feedback mechanism through Ca2+ in neutrophils.

Animals↗
PubMed1993

Effect of microbial and mite proteases on low and high molecular weight kininogens. Generation of kinin and inactivation of thiol protease inhibitory activity.

Kinin release from guinea pig plasma high molecular weight kininogen (HMWK) induced by various microbial and mite proteases has been demonstrated previously (Molla, A., Yamamoto, T., Akaike, T., Miyoshi, S., and Maeda, H. (1989) J. Biol. Chem. 264, 10589-10594; Maruo, K., Akaike, T., Matsumura, Y., Kohmoto, S., Inada, Y., Ono, T., Arao, T., and Maeda, H. (1991) Biochim. Biophys. Acta 1074, 62-68). In this paper, we describe the effects of various microbial and mite proteases on low molecular weight kininogen (LMWK) and HMWK from human plasma. A protease from the house dust mite Dermatophagoides farinae (Df-protease) directly liberated kinin from both LMWK and HMWK to a significant degree. The Km, kcat, and kcat/Km values for kinin generation from LMWK were 3.24 microM, 0.61 s-1, and 1.9 x 10(5) M-1 x s-1, respectively, and those for kinin generation from HMWK were 0.56 microM, 0.12 s-1, and 2.1 x 10(5) M-1 x s-1, respectively; kcat/Km values for Df-protease were comparable with that for glandular kallikrein. In contrast, microbial proteases showed only weak kinin-releasing activity from both human plasma kininogens. Four of ten different microbial proteases liberated kinin from LMWK, and only serratial 56-kDa protease released kinin from HMWK. Furthermore, Df-protease markedly inactivated the thiol protease inhibitory activity of LMWK and HMWK, whereas all microbial proteases (as well as the endogenous protease trypsin) did not affect this inhibitory activity of both kininogens from human plasma.

Animals↗
PubMed1993

The lectin concanavalin A stimulates a protein-tyrosine kinase p72syk in peripheral blood lymphocytes.

We report that the activation of porcine peripheral blood lymphocytes (PBL) by lectin concanavalin A (Con A) led to the increase in tyrosine phosphorylation on 84-, 72-, 55-, 40-, and 33-kDa proteins. A non-receptor protein-tyrosine kinase (PTK), p72syk (Taniguchi et al. (1991) J. Biol. Chem. 266, 15790-15796), was detected in PBL around 0.1% of total protein and distributed in both particulate and cytosolic fractions. Furthermore, Con A induced a rapid activation of p72syk within 1 min in a manner similar to the time course of Con A-induced protein-tyrosine phosphorylation. These results suggest that p72syk plays a certain role in the activation of PBL and that p72syk may be one of the major non-receptor PTKs in T cells as well as in B cells.

Animals↗
PubMed1993

Pyroelectric current of oriented purple membrane films.

By applying an electric field(2 to 5.5 Volt/mm) to a suspension of purple membrane from Halobacterium halobium, oriented purple-, purple blue-, and blue-colored membrane films have been formed on conductive glasses. Pyroelectric currents have been found for these three types of oriented films at temperatures between 25 and 160 degrees C. The oriented purple-colored membrane (PM) film has positive current peaks at around 60, 80, and 115 degrees C and reverses its sign at around 130 degrees C, followed by a negative peak at 145 degrees C. (Instead of the positive peak at 80 degrees C, a negative peak has been found around 90 degrees C for purple blue- and blue-colored membrane films.) The current peak at 80 degrees C for the PM film could be due to a conformational change in the protein, which includes at least a change in the environment of the chromophore. The sign-reversal current at 130 degrees C for the PM film seems to be related to denaturation of the protein. These peak temperatures in the pyroelectric current of the PM films, i.e., 60, 80, and 115 degrees C, have been found to agree well with some characteristic temperatures observed by Shnyorov et al. (D-H exchange), Jackson et al. (DSC and absorption spectra of visible light), and Hiraki et al. (X-ray, absorption spectra).

Bacteriorhodopsins↗
PubMed1993

Drug effects on distribution of [3H]3,4-methylenedioxymethamphetamine in mice.

The present study was undertaken to examine the drug interactions between 3,4-methylenedioxymethamphetamine (MDMA) and paroxetine or several compounds including the 3,4-methylenedioxybenzyl (piperonyl) group in mice. The time course of radioactivity in the mouse brain after i.v. administration of the tracer amount (approximately 70 ng/kg) of [3H]MDMA was altered significantly by coinjection of carrier MDMA (15 mg/kg) or by pretreatment with paroxetine (10 mg/kg, i.p., 5 min). Furthermore, the radioactivity in the brain 60 min after injection of [3H]MDMA was increased significantly by pretreatment with paroxetine, but not by pretreatment with 6-nitroquipazine, fluoxetine, clomipramine, GBR 12909 or desipramine, indicating that paroxetine-induced alteration of the brain radioactivity was not due to the inhibitory effect of 5-hydroxytryptamine (5-HT) uptake of paroxetine. The radioactivity in the brain 60 min after injection of [3H]MDMA was increased significantly by pretreatment with 3,4-methylenedioxyamphetamine (MDA), MDMA, 1-piperonylpiperazine and N, alpha-dimethylpiperonylamine, but not by pretreatment with piperonylacetone, piperonyl butoxide and piperonyl isobutyrate. HPLC analyses indicated that the alteration of brain radioactivity 60 min after injection of [3H]MDMA was, in part, due to inhibition in the metabolism of [3H]MDMA to radioactive metabolite(s). The present results suggest that a specific mechanism for the 3,4-methylenedioxyphenyl group which rapidly alters the disposition and metabolism of [3H]MDMA may exist in brain and peripheral organs of mice.

3,4-Methylenedioxyamphetamine↗
PubMed1993

[Clinical evaluation of two- and three-dimensional imaging of helical scanning CT in the upper abdomen].

To evaluate the usefulness of helical scanning CT of the upper abdomen, 30 patients with hepatic, adrenal, pancreatic and renal disease were examined using a Toshiba CT system, the Xforce. Helical scanning CT data were acquired using up to 20 continuous 1.5-second rotations, with a 1.5-3 ml bolus injection of contrast medium, and during a single breath-hold. Helical scanning provided both better data continuity and resolution than conventional scanning. The axial images with a slice thickness of 5 mm were not inferior in quality to equivalent images acquired by conventional CT, and multiplanar reconstruction images were superior. Targeted structures could be easily obtained because helical scanning CT permits image reconstruction in any direction. Using a CEMAX-VIPstation, we generated three-dimensional display images of high-density structures from the postcontrast data acquired with helical scanning. On these images, it was easy to observe the high-density tumors three-dimensionally and to determine the position of the tumors relative to the high-density surrounding organs. In conclusion, helical scanning CT was considered to be useful in clinical diagnosis involving the upper abdomen.

Adult↗