Showing papers by "Hiroshi Maeda published in 2002"

Role of Nitric Oxide in Host Defense in Murine Salmonellosis as a Function of Its Antibacterial and Antiapoptotic Activities

Abstract: Host defense functions of nitric oxide (NO) are known for many bacterial infections In this study, we investigated the antimicrobial effect of NO in murine salmonellosis by using inducible NO synthase (iNOS)-deficient mice infected with an avirulent or virulent Salmonella enterica serovar Typhimurium strain All iNOS-deficient mice died of severe septicemia within 6 days after intraperitoneal injection with an avirulent strain (LT2) to which wild-type mice were highly resistant; 50% lethal doses (LD(50)s) of the LT2 strain for iNOS-deficient and wild-type mice were 30 CFU and 7 x 10(4) CFU, respectively Lack of NO production in iNOS-deficient mice was verified directly by electron spin resonance spectroscopy Bacterial yields in liver and blood were much higher in iNOS-deficient mice than in wild-type mice throughout the course of infection Very small amounts of a virulent strain of serovar Typhimurium (a clinical isolate, strain Gifu 12142; LD(50), 50 CFU) given orally caused severe septicemia in iNOS-deficient animals; wild-type mice tolerated higher doses (LD(50), 6 x 10(2) CFU) Histopathology of livers from infected iNOS-deficient mice revealed extensive damage, such as diffuse hepatocellular apoptosis and increased neutrophil infiltration, but livers from infected wild-type mice showed a limited number of microabscesses, consisting of polymorphonuclear cells and macrophages and low levels of apoptotic change The LT2 strain was much more susceptible to the bactericidal effect of peroxynitrite than the Gifu strain, suggesting that peroxynitrite resistance may contribute to Salmonella pathogenicity These results indicate that NO has significant host defense functions in Salmonella infections not only because of its direct antimicrobial effect but also via cytoprotective actions for infected host cells, possibly through its antiapoptotic effect

Tumor-targeted Delivery of Polyethylene Glycol-conjugated d-Amino Acid Oxidase for Antitumor Therapy via Enzymatic Generation of Hydrogen Peroxide

Abstract: Hydrogen peroxide (H(2)O(2)) is a strong oxidant that induces apoptosis of tumor cells in vitro. Here, we investigated the antitumor activity of an H(2)O(2)-generating enzyme, D-amino acid oxidase (DAO), and its conjugate with polyethylene glycol (PEG; PEG-DAO). Compared with DAO, PEG-DAO showed improved pharmacokinetic parameters in mice after i.v. injection. PEG-DAO administered i.v. accumulated selectively in tumor tissue with insignificant accumulation in normal organs and tissues. To generate cytotoxic H(2)O(2) at the tumor site, PEG-DAO was first administrated i.v. to tumor-bearing mice. After an adequate lag time, the substrate of DAO, D-proline, was injected i.p. This treatment resulted in significant suppression of tumor growth compared with tumor growth in control animals (not given treatment; P < 0.001). Similar treatment with native DAO showed no effect under the same conditions. Oxidative metabolites were significantly increased in solid tumors by administration of PEG-DAO followed by D-proline (P < 0.002, compared with the group receiving no treatment), as evidenced by thiobarbituric acid-reactive substance assay. This treatment did not affect results from the metabolites in the liver and kidney. These findings suggest that tumor-targeted delivery of DAO is accomplished by using pegylated enzyme and thereby taking advantage of the enhanced permeability and retention effect in solid tumor. PEG-DAO thus delivered together with D-proline produces remarkable antitumor activity via extensive generation of H(2)O(2).

Identification of bradykinin receptors in clinical cancer specimens and murine tumor tissues

Abstract: Bradykinin (BK) has multiple pathophysiologic functions such as induction of vascular permeability and mitogenesis, and it triggers the release of other mediators such as nitric oxide in inflammatory and cancer tissues. To explore the pathophysiologic roles of BK in tumor, we examined the distribution of BK B2 receptors in human adenocarcinoma (lung, stomach), lymphoma (lymph node), hepatoma, squamous cell carcinoma (lung) and carcinoid (duodenum), and in mouse colon adenocarcinoma 38 (C-38) and sarcoma 180 (S-180) tumor tissues. Immunohistochemical staining of tumor tissues with an anti-BK B2 receptor antibody, or autoradiography with the B2 receptor antagonist [125I]HOE 140 (D-Arg-[Hyp Thi D-Tic Oic8]-BK) and the B2 receptor agonist [3H]BK indicated the presence of B2 receptors in all human tumor cells and murine S-180 and C-38 cells. Specific binding of [3H]HOE 140 was observed in S-180 cells with a Kd of 2.1 nM. Binding of [125I]HOE 140 to S-180 cells was competed by an excess amount (20–100 times) of nonradiolabeled HOE 140 or BK, but not by BK B1 receptor agonist des-Arg9-BK. These results provide direct evidence that the BK B2 receptor is expressed in human cancer and experimental murine tumors, which suggests a potential role for BK in inducing pathologic signal transduction in cancer growth and progression, nitric oxide production and vascular permeability enhancement in tumors. BK antagonists may thus have applications in the modulation of cancer growth and in paraneoplastic syndromes. © 2001 Wiley-Liss, Inc.

Enhanced Permeability and Retention (EPR) Efect: Basis for Drug Targeting to Tumor

Abstract: Tumor vascular permeability is becoming increasingly important in tumor biology because of its critical role in tumor growth and perhaps in metastasis, as well as in the selective delivery of anticancer agents, particularly macromolecular compounds, to tumors (see Refs. 1–5 for reviews). This issue of vascular permeability is significant primarily in tumorous tissues (and in inflammatory tissues). Macromolecular (or polymeric) drugs are of interest because they are in the class of substances manifesting enhanced extravasation in tumor tissue. The tumor-selective phenomenon has been characterized and termed the enhanced permeability and retention (EPR) effect of macromolecules and lipidic particles (2–4). One can best take advantage of this unique EPR effect for tumor-targeted delivery of drugs. Thus, polymeric drugs and microparticles, including micellar compounds or liposomes, can be delivered with greater selectivity to tumors because of the EPR effect.

Growth and Superconductivity of (BiPb)2Sr2Ca2Cu3O10+δ Single-Crystal Whiskers

Abstract: (BiPb)2Sr2Ca2Cu3O10+δ ((BiPb)2223) single-crystal whiskers with a length of about 2 mm were grown by annealing a sintered Te-doped (BiPb)2Sr2Ca2Cu3Ox precursor pellet. The pellet was formed by mixing single-phase (BiPb)2223 with TeO2; the content ratio of TeO2 to Bi2223 was 0.5. For the growth, it is very important to use (BiPb)2223 single-phase powder as a precursor. The whiskers contain no Te and their composition is Ca-rich (BiPb)2(Sr0.3Ca0.7)4Cu3Ox. The whiskers have excellent crystallinity and a critical temperature of about 106 K. The critical current, which exhibits a multibranched structure in the current–voltage characteristics due to the intrinsic Josephson junctions along the c-axis, is quite uniform, showing that the whiskers are homogeneous and of good quality.

Carrier density control of Bi-2212 whiskers

Abstract: The superconducting transition temperature ( T c ), the junction resistance ( R N ) and the critical current density along the c -axis ( J c ) of Bi-2212 whiskers with different oxygen content have been measured. T c showed a systematical change for the c -axis length. Since the change of c -axis length corresponds to the change of oxygen content, it can be considered that this behavior explains the clear change in carrier density on the whisker from overdoped to underdoped region. J c of intrinsic Josephson junctions fabricated on the whisker exponentially decreases with decreasing the carrier density on whiskers. It indicates that the transport along the c -axis is due to a tunneling process through an insulating barrier.

Use of corfolsin dalopate following cardiac surgery in a neonate.

Abstract: A FEMALE neonate, weighing 2,690 g, developed severe cyanosis immediately after birth, and was diagnosed as having complex heart anomaly (truncus arteriosus, interruption of aortic arch, aortopulmonary septal defect, patent ducts arteriosus, and persistent foramen ovale). Despite support with dopamine, dobutamine, and epinephrine, congestive heart failure developed. Therefore, total correction surgery was scheduled to take place on the patient's twenty-first day of life. Anaesthesia was induced and maintained with fentanyl (25 μg/kg) and midazolam (0.3 mg/kg). Surgery was performed under the moderately hypothermic (25°C) cardiopulmonary bypass (CPB) with a total flow of 2.8 l.min -1 .m 2 , CPB was started 55 min after the anesthetic induction. The interval from the start of CPB to the initial attempt to wean the patient from CPB with sufficient body temperature recovery (36.2°C) was 5 h and 20 min. The attempt was made to discontinue CPB with the aid of dopamine (4 - 8 μg.kg -1 .min -1 ) and dobutamine (5-8 μg.kg -1 .min -1 ). However, decreasing the bypass flow to less than 1.5 l.min -1 .m -2 resulted in sustained hypotension. Adding epinephrine (0.5 μg/kg/min) and isoproterenol (0.1 μg.kg -1 .min -1 ) did not improve the patient's hemodynamics; her systemic mean arterial pressure while still on partial bypass was ≤ 30 mmHg, while her central venous pressure (CVP) was approximately 17 mmHg. The addition of an infusion of milrinone (0.5 (μg.kg -1 .min -1 ) for approximately 40 min also had no significant effect. Echocardiography (using an epicardial probe) showed an adequate surgical repair. At this point, with the patient back on full bypass support all inotropic agents were discontinued. We next administered a combination of colforsin dalopate HCI (0.25 μg.kg -1 .min -1 ') and dopamine (5 μg.kg -1 .min -1 ). The patient's CPB flow rate decreased to 1.0 l.min -1 .m -2 and CVP was controlled at 8-11 mmHg. Over the next 30 min, the patient's mean arterial pressure increased from 35 to 65 mmHg, and her heart rate increased from 140 to 170 beats/min. After approximately 20 min of stable conditions, CPB was successfully discontinued. Her postweaning hemodynamic parameters showed heart rate, mean systemic arterial pressure, and CVP levels in the ranges of 170-180 beats/min, 55-65 mmHg, and 11-13 mmHg, respectively, Arterial blood gas analysis did not show metabolic acidosis, hypercarbia, or hypoxemia, The surgery terminated 2 h after the CPB weaning, Hemodynamic parameters recorded after each attempt to discontinue bypass are summarized in table 1. After being transferred to the intensive care unit, the patient's heart rate continued to increase, reaching 190 beats/min. Her colforsin infusion was discontinued while dopamine was maintained. Two hours later, her mean arterial pressure decreased to 35 mmHg from 60 mmHg, her heart rate decreased to 140 beats/min from 170 beats/min, and CVP increased from 11 mmHg to 17 mmHg. An infusion of epinephrine was added, but without success. Therefore, approximately 1 h later, colforsin dalopate HCl infusion (0.25 μg.kg -1 .min 1 ) was restarted. Mean arterial pressure and heart rate quickly increased to 65 mmHg and 178 beats/min, respectively. Colforsin was discontinued without difficulty 5 h later.

Antitumor agents and process for producing the same

Abstract: Antitumor agents containing, as the active ingredient, a metal porphyrin derivative having a hemoxygenase activity and bonded to an amphipathic or water-soluble polymer (in particular, Zn-protoporphyrin (Zn-PP) bonded to polyethylene glycol). Because of being bonded to an amphipathic or water-soluble polymer such as polyethylene glycol, the active ingredient can be administered by intravenous injection and can exert a remarkable antitumor effect owing to tumor-selective delivery.

Antiradicals and fat compositions, foods, drinks, drugs or feeds containing the antiradicals

Abstract: It is intended to obtain highly active and fat-soluble antiradicals originating in a natural substance whereby the stability of foods (fat compositions) can be elevated and disorders caused by oxidation in vivo can be prevented simultaneously. Namely (1) an antiradical containing 4-vinyl-2,6-dimethoxyphenol as the active ingredient; (2) an antiradical comprising an extract of crude rapeseed oil containing 4-vinyl-2,6-dimethoxyphenol; (3) a crude rapeseed oil extract containing 4-vinyl-2,6-dimethoxyphenol in a concentrated state characterized by being prepared by treating crude rapeseed oil with an alcohol or an aqueous alcohol or distilling it; and (4) an antiradical containing these three types of crude rapeseed oil extracts.

The molecular surface of proteolytic enzymes has an important role in stability of the enzymatic activity in extraordinary environments.

Abstract: It is scientifically and industrially important to clarify the stabilizing mechanism of proteases in extraordinary environments We used subtilisins ALP I and Sendai as models to study the mechanism Subtilisin ALP I is extremely sensitive to highly alkaline conditions, even though the enzyme is produced by alkalophilic Bacillus, whereas subtilisin Sendai from alkalophilic Bacillus is stable under conditions of high alkalinity We constructed mutant subtilisin ALP I enzymes by mutating the amino acid residues specific for subtilisin ALP I to the residues at the corresponding positions of amino acid sequence alignment of alkaline subtilisin Sendai We observed that the two mutations in the C-terminal region were most effective for improving stability against surfactants and heat as well as high alkalinity We predicted that the mutated residues are located on the surface of the enzyme structures and, on thebasis of three-dimensional modelling, that they are involved in stabilizing the conformation of the C-terminal region As proteolytic enzymes frequently become inactive due to autocatalysis, stability of these enzymes in an extraordinary environment would depend on the conformational stability of the molecular surface concealing scissile peptide bonds It appeared that the stabilization of the molecular surface structure was effective to improve the stability of the proteolytic enzymes

[Application of HPLC method for the measurement of hyaluronan in pleural fluid--a new alternative of cellulose acetate membrane electrophoresis].

Abstract: We examined whether high-performance liquid chromatography(HPLC) method was more suitable for the measurement of hyaluronan(HA) in pleural fluid than the standardized electrophoretical method Forty-four samples of pleural fluid were measured both by the HPLC method and by the electrophoretical method The HA values measured by the HPLC method did not show significant correlation(r = 033) to those measured by the electrophoretical method We investigated the reason of this insufficiency of the correlation The electrophoretical method was not specific for the measurement of HA and other glycosaminoglycan, such as chondroitin could be measured by this method Therefore, the HA value measured by this method was higher than that measured by the HPLC method The other problem was some loss of HA during the pre-treatment of samples with percloric acid in the electrophoretical method, which was needless in the HPLC method We concluded that the HPLC method was more appropriate than the electrophoretical method for the measurement of hyaluronan in pleural fluid

Study on glutathionesulfonic acid sodium salt as biodistribution promoter for thiopental sodium.

Abstract: The effects of glutathione (GSH) and glutathionesulfonic acid sodium salt [N-(N-gamma-L-glutamyl-L-beta-sulfoalanyl)glycine sodium salt, GSO3Na], which is a minor metabolite of GSH, on the pharmacokinetics of thiopental sodium were investigated in rats. The concomitant use of GSO3Na with thiopental sodium significantly increased the tissue-to-plasma concentration ratio (Kp) of thiopental sodium 60 min after its administration in the heart, lung, brain, liver, kidney, and spleen, while GSH did not affect them. On the other hand, the Kp value of thiopental sodium 5 min after its administration with concomitant GSO3Na decreased significantly only in the spleen. Neither GSO3Na nor GSH changes the pharmacokinetic parameters of thiopental sodium. Significant change of the binding ratio of thiopental sodium to bovine serum albumin (BSA) was not observed by the addition of less than 5-fold GSO3Na. About 50% of thiopental sodium was bound to the brain, lung or liver, however, no significant change of this binding ratio was observed by the concomitant use of GSO3Na. The partition coefficient of thiopental sodium apparently increased by the concomitant use of GSO3Na but not by GSH. This phenomenon seemed to be concerned with a mechanism to increase the Kp values of thiopental sodium in the tissues. The increment in the drug distribution to tissues with concomitant GSO3Na observed in this study is useful information for the application of drug combinations as a biodistribution promoter.

Hyaluronan during liver regeneration after partial hepatectomy: transient accumulation in the tissue and elevation of the serum concentration.

Abstract: Hyaluronan (HA) is a widely distributed nonsulfated glycosaminogtycan with many physiological and biological functions including promotion of cell proliferation and migration. Accumulation of HA in extracellular matrix is an early event in tissue repair, and also the appearance and removal of HA at specific loci are precisely controlled during embryogencsis. Liver regeneration following partial hepatectomy (PH) is well established in vivo system to study cell proliferation and tissue reorganization. Therefore we studied tissue distribution of HA, its serum level, and the expression patterns of the genes of HA synthases (HAS1, HAS2, HAS3) in regenerating rat liver after PH. In the regenerating liver, HA were transiently accumulated along sinusoid from 24 hour to 48 hour after PH. Normally, low concentrations of HA circulate in the blood, but, during the liver regeneration serum concentration of HA was transiently elevated with the same temporal pattern as the tissue accumulation of HA. Semi-quantitative RT-PCR analyses showed expression level of HAS1 in regenerating liver was elevated immediately after PH and was kept at high level for 1 week. Transient accumulation and synthesis of HA may play important roles in liver regeneration by remodeling the microenvironment.