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Biomedical subjects

Y Nitta

Publications and source records attributed to Y Nitta.

At least 37 records · Page 2Linked to original sources
PubMed2001

Targeted systemic chemotherapy using magnetic liposomes with incorporated adriamycin for osteosarcoma in hamsters.

To control the growth of primary tumors effectively with systemic chemotherapy, we recently developed intravenously administered small-sized magnetic liposomes as an anticancer drug carrier. We previously reported that intravenously administered magnetic liposomes with incorporated adriamycin (magnetic ADR liposomes) effectively delivered ADR to the target site where a permanent magnet was implanted. In the present study, the therapeutic efficacy of this novel treatment approach, which involves a combination of magnet implantation at the target site and intravenous administration of magnetic liposomes, was further evaluated by comparing tumor growth rates among different administration modalities and by histological examination of treated tumors. Small-sized magnetic ADR liposomes with a mean diameter of 146 nm were prepared by the reverse-phase evaporation method. Syrian male hamsters inoculated with osteosarcoma, Os515, in the right hind limb were studied 7 days after inoculation. One day prior to the animal study, either a permanent magnet (with magnetic force) or non-magnetic alloy (without magnetic force) was implanted in the center of the tumors. Treatment with magnetic ADR liposomes under magnetic force showed significantly greater antitumor activity than intravenous administration of ADR solution or that of magnetic ADR liposomes without magnetic force. ADR administered as magnetic liposomes eliminated weight loss of hamsters, one of the side effects produced by ADR. Interestingly, magnetic liposomes (without incorporated ADR) given under magnetic force also suppressed the tumor growth. The selective accumulation of magnetite particles in the tumor blood vessels was observed by histological examination. These results suggest that this systemic chemotherapy can effectively control the primary tumor without significant side effects, due to the targeting of magnetic ADR liposomes.

Animals↗
PubMed2001

Effect of thermosensitive liposomal doxorubicin with hyperthermia on primary tumor and lung metastases in hamster osteosarcoma.

We evaluated the effect of intravenous thermosensitive liposomal doxorubicin (TL-DOX) together with local hyperthermia on primary tumors in highly metastatic hamster osteosarcoma. This combination resulted in higher DOX concentrations in plasma, primary tumors and lungs than standard DOX under the same conditions. Tumor growth and lung metastasis were also inhibited more by TL-DOX and hyperthermia than by hyperthermia alone, DOX with or without hyperthermia, and TL-DOX without hyperthermia. In addition, gains in hamster body weight were not suppressed. These results suggest that the combination of TL-DOX and hyperthermia can control primary tumors and suppress lung metastasis in hamsters.

Animals↗
PubMed2000

Adeno-associated virus vector transduction of vascular smooth muscle cells in vivo.

Adeno-associated virus (AAV) vectors might offer solutions for restenosis and angiogenesis by transducing nondividing cells and providing long-term gene expression. We investigated the feasibility of vascular cell transduction by AAV vectors in an in vivo rabbit carotid artery model. Time course of gene expression, inflammatory reaction to the vector, and effects of varying viral titer, exposure time, and intraluminal pressures on gene expression were examined. Recombinant AAV vectors with an Rous sarcoma virus promoter and alkaline phosphatase reporter gene were injected intraluminally into transiently isolated carotid segments. Following transduction, gene expression increased significantly over 14 days and then remained stable to 28 days, the last time point examined. Medial vascular smooth muscle cells were the main cell type transduced even with an intact endothelial layer. Increasing the viral titer and intraluminal pressure both enhanced transduction efficiency to achieve a mean of 34 +/- 7% of the subintimal layer of smooth muscle cells expressing gene product. A mild inflammatory reaction, composed of T cells with only rare macrophages, with minimal intimal thickening was demonstrated in 40% of transduced vessels; inflammatory cells were not detected in sham-operated control arteries. These findings demonstrate that AAV is a promising vector for intravascular applications in coronary and peripheral vascular diseases.

Alkaline Phosphatase↗
PubMed2000

Testing of SHIRPA, a mouse phenotypic assessment protocol, on Dmd(mdx) and Dmd(mdx3cv) dystrophin-deficient mice.

The SHIRPA protocol was proposed as a rapid, comprehensive screening method for qualitatively abnormal phenotypes in the mouse (Rogers et al., Mamm Genome 8, 711, 1997). This screening technique is currently being used to identify mutants induced by N-ethylnitrosourea (ENU) mutagenesis (Brown and Nolan, Hum Mol Genet 7, 1627, 1998). SHIRPA can be used to identify mutants with neuromuscular abnormalities, but the sensitivity of the protocol is unknown. We tested two dystrophin-deficient mutants Dmd(mdx) and Dmd(mdx3cv), both of which are indistinguishable from wild-type by a simple visual assessment, at different ages, using the primary screen of the SHIRPA protocol. The most dramatic observation was that both Dmd(mdx) and Dmd(mdx3cv) mice showed extreme fatigue after testing, while mice from the same C57BL strains appeared unaffected. Each strain of dystrophin-deficient mice showed a different profile in locomotor activity and deficiencies in the wire maneuver, righting reflex, and negative geotaxis tests. Furthermore, the wire maneuver test indicated an earlier onset of muscular impairment in Dmd(mdx) than Dmd(mdx3cv) mice. These data suggest that the SHIRPA primary screen is effective not only in identifying subtle neuromuscular mutants, but also in distinguishing qualitative differences between mutants with neuromuscular abnormalities.

Animals↗
PubMed2000

Gene gun-mediated delivery of an interleukin-12 expression plasmid protects against infections with the intracellular protozoan parasites Leishmania major and Trypanosoma cruzi in mice.

An interleukin-12 (IL-12) expression plasmid was transferred, using a gene gun, to mice infected with Leishmania major or Trypanosoma cruzi. Transfer of the IL-12 gene to susceptible BALB/c mice resulted in regression of lesion size and reduced the number of parasites in draining lymph nodes (LN) at the site of L. major infection. Coincident with these protective effects, the T-helper type (Th) response shifted towards Th1, as evaluated by cytokine production in vitro and L. major-specific antibody responses. Protective effects of the IL-12 gene were also observed in T. cruzi infection. Treatment of BALB/c mice infected with T. cruzi enhanced the production of interferon-gamma (IFN-gamma) by spleen cells, while suppressed production of interleukin-10 (IL-10) compared with control mice. Administration of anti-CD4 or anti-CD8 monoclonal antibody (mAb) abolished the protective immunity against T. cruzi infection, and treatment with the IL-12 gene could not restore the resistance in these mice. Mice depleted of natural killer (NK) cells with anti-asialo GM1 also became susceptible to infection, while the resistance was restored when these mice were treated with the IL-12 gene. Thus, target cells for the treatment appear to be CD4+ and CD8+ T cells, which are ordinarily activated by NK cells. These results suggest that the transfer of cytokine genes using a gene gun is an effective method for investigating the roles of cytokines and gene therapy in infectious diseases.

Animals↗
PubMed2000

Extensive cell death in thymocytes in colon 26-induced cachectic mice.

Extensive atrophy has been reported to occur in the thymus in a cancer-burden state but the mechanisms of this atrophy have not been fully elucidated. We investigated changes in the thymus in tumour-bearing mice inoculated with two subclones of the murine colon 26 adenocarcinoma cell line: clone 5 (non-cachectic) and clone 20 (cachectic). In clone 20 mice, body weights and thymocyte numbers decreased significantly compared with controls. Flow cytometric analysis of the thymocytes demonstrated that the frequency of single positive cells (CD4+ CD8- and CD4- CD8+) was significantly increased and that of double positive cells (CD4+ CD8+) was significantly decreased in clone 20 mice and, to a lesser extent, in clone 5 mice compared with controls. Serum levels of interleukin 6 and granulocyte-macrophage colony-stimulating factor (GM-CSF) were significantly elevated. These results suggested that thymocyte apoptosis was accelerated in the cancer-cachectic state, and increased GM-CSF might be partly responsible for thymic atrophy.

Adenocarcinoma↗
PubMed2000

Inhibitory effect of liposomal MDP-Lys on lung metastasis of transplantable osteosarcoma in hamster.

MDP-Lys (N2-[(N-acetylmuramyl)-L-alanyl-D-isoglutaminyl]-N6-stearoyl-L-lysine), a macrophage activator, is a lipophilic derivative of muramyl dipeptide (MDP). Multilamellar liposome incorporated MDP-Lys was prepared using phosphatidylcholine and phosphatidylserine by conventional film method, and its inhibitory effect on lung metastasis was compared with MDP-Lys as a solution in hamster's osteosarcoma. The lung metastatic rates after transplantation of the tumor to a lower extremity, in which the extremity was amputated 3 weeks later, were 50% and 100% 3 and 7 weeks, respectively, after transplantation. The rates after amputation were reduced by the treatment with MDP-Lys proportionally to the logarithmic MDP-Lys dose, and the rates 7 weeks after transplantation were 55% and 60%, respectively, in the MDP-Lys solution (50 microg/day) and liposomal MDP-Lys (20 microg twice/week) groups. Fifty percent of hamsters treated with liposomal MDP-Lys survived for more than 6 months. Considering that hamsters had a lung metastasis rate of 50% before MDP-Lys treatment, liposomal MDP-Lys given at a dose of 20 microg twice/week was effective for inhibiting lung metastasis at a far lower dose of MDP-Lys than that given as a solution (40 microg vs. 350 microg per week). No significant side effect of liposomal MDP-Lys, as evaluated by the comparison of body weight changes among differently treated hamsters, was detected. This greater inhibitory effect of liposomal MDP-Lys can be considered to be due to the longer retention of the liposomal form in the lung.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed2000

Targeted delivery of anticancer drugs with intravenously administered magnetic liposomes in osteosarcoma-bearing hamsters.

Although active targeting of anticancer drugs using magnetically responsive carriers is a very attractive treatment approach for solid tumors, successful results are limited. In particular, the therapeutic utility of intravenously administered magnetically responsive carriers has to date not been clearly established. The present study investigates magnetic liposomes designed to act as anticancer drug carriers, which can be effectively delivered to solid tumors via intravenous administration. Magnetic liposomes with incorporated adriamycin (magnetic ADR liposomes) were prepared by the reverse-phase evaporation method, and an in vivo study was carried out to assess the magnetic targeting of these liposomes to hamster osteosarcoma. The average diameter of liposomes thus prepared was 146 nm. Syrian male hamsters inoculated with osteosarcoma, Os515, in the right hind limb were studied 7 days after inoculation. After the hamsters had received an intravenous administration of either magnetic ADR liposomes or ADR solution (corresponding to 5 mg ADR/kg), the ADR concentrations in plasma, tumor, liver, lung, heart, and kidney were determined at designated time intervals. Administration of magnetic ADR liposomes under magnetic force using a permanent magnet (0.4 tesla) implanted in solid tumor produced an approximately 4-fold higher maximum ADR concentration in the tumor than did administration of ADR solution. The former administration modality induced an increase in ADR concentration in the liver and lung and a decrease in the heart compared with concentrations produced by the latter. The present results indicated that intravenously administered magnetic ADR liposomes can be used to effectively deliver ADR to osteosarcoma implanted with a magnet, as well as to the lung, a common site of metastases for osteosarcoma. Our results also suggest that this new treatment approach, which involves a combination of magnet implantation at the target site and intravenous administration of magnetic liposomes, can improve the clinical chemotherapy of solid tumors.

Animals↗
PubMed1999

DNA immunization with Plasmodium falciparum serine repeat antigen: regulation of humoral immune response by coinoculation of cytokine expression plasmid.

We immunized mice with plasmid expressing the 47-kDa amino-terminal domain of the Plasmodium falciparum serine repeat antigen (SERA) using gene gun and investigated humoral immune response to SERA antigen. Significant SERA-specific IgG was observed in BALB/c mice after immunization three times with SERA expression plasmid. Furthermore, these levels were increased by the coinoculation of cytokine (IFN-gamma, IL-4, GM-CSF, or IL-12) expression plasmid. In respect to the SERA-specific Ig subclasses, coinoculation of IFN-gamma, GM-CSF, or IL-12 expression plasmid increased the levels of SERA-specific IgG2a, and these were much higher than that in mice immunized with SERA expression plasmid alone. In contrast to the SERA-specific IgG2a, coinoculation of any cytokine expression plasmid did not change the levels of SERA-specific IgG1. These results indicate that cytokine expression plasmid enhances and regulates humoral immune response elicited by SERA DNA immunization.

Animals↗
PubMed1999

Crystal structure of beta-amylase from Bacillus cereus var. mycoides at 2.2 A resolution.

The crystal structure of beta-amylase from Bacillus cereus var. mycoides was determined by the multiple isomorphous replacement method. The structure was refined to a final R-factor of 0.186 for 102,807 independent reflections with F/sigma(F) > or = 2.0 at 2.2 A resolution with root-mean-square deviations from ideality in bond lengths, and bond angles of 0.014 A and 3.00 degrees, respectively. The asymmetric unit comprises four molecules exhibiting a dimer-of-dimers structure. The enzyme, however, acts as a monomer in solution. The beta-amylase molecule folds into three domains; the first one is the N-terminal catalytic domain with a (beta/alpha)8 barrel, the second one is the excursion part from the first one, and the third one is the C-terminal domain with two almost anti-parallel beta-sheets. The active site cleft, including two putative catalytic residues (Glu172 and Glu367), is located on the carboxyl side of the central beta-sheet in the (beta/alpha)8 barrel, as in most amylases. The active site structure of the enzyme resembles that of soybean beta-amylase with slight differences. One calcium ion is bound per molecule far from the active site. The C-terminal domain has a fold similar to the raw starch binding domains of cyclodextrin glycosyltransferase and glucoamylase.

Amino Acid Sequence↗
PubMed1999

A crack model of the Hiroshima atomic bomb: explanation of the contradiction of "Dosimetry system 1986".

There has been a large discrepancy between the Dosimetry system 1986 (DS86) and measured data, some of which data in Hiroshima at about 1.5 km ground distance from the hypocenter are about 10 times larger than the calculation. Therefore its causes have long been discussed, since it will change the estimated radiation risks obtained based on the Hiroshima and Nagasaki data. In this study the contradiction was explained by a bare-fission-neutron leakage model through a crack formed at the time of neutron emission. According to the present calculation, the crack has a 3 cm parallel spacing, which is symmetric with respect to the polar axis from the hypocenter to the epicenter of the atomic bomb. We made also an asymmetric opening closing 3/4 of this symmetric geometry, because there are some data which shows asymmetry. In addition, the height of the neutron emission point was elevated 90 m. By using the asymmetric calculation, especially for long distant data located more than 1 km, it was verified that all of the activity data induced by thermal and fast neutrons, were simultaneously explained within the data scattering. The neutron kerma at a typical 1.5 km ground distance increases 3 and 8 times more than DS86 based on the symmetric and asymmetric model, respectively.

Humans↗
PubMed1999

Circulating levels of soluble CD30 and other markers in colorectal cancer patients.

In a search for new biologic serum tumor markers with prognostic value we evaluated the soluble form of the CD30 (sCD30), a marker of cells producing T helper 2 (Th2)-type cytokines, interleukin-1 receptor antagonist (IL-1ra), soluble interleukin-2 receptor (sIL-2R), soluble tumor necrosis factor -type I, -type II (sTNF-R55, -75) and immunosuppressive acidic protein (IAP) in patients, with advanced colorectal cancer. The data showed that abnormal levels of sCD30 were detected in eight (80.0%) out of ten patients. In contrast, sCD30 levels were not detected in healthy volunteers. The relationship between sCD30, sIL-2R and IAP were positively correlated. In contrast, sCD30 and IL-1ra were negatively correlated. These results suggested that IL-1ra may play a role, at least in part, to inhibit CD30 release, and sCD30 appears to be a new biologic serum tumor marker of possible use in the clinical setting of cancer patients.

Adult↗
PubMed1998

Systemic delivery of interleukin 10 by intramuscular injection of expression plasmid DNA prevents autoimmune diabetes in nonobese diabetic mice.

We previously demonstrated that intramuscular plasmid injection serves as a useful method of long-term systemic delivery of cytokines. In the present study, we assess intramuscular DNA injection as a means of systemically delivering interleukin 10 (IL-10), a cytokine with immunosuppressive properties, and preventing the progression of autoimmune diabetes in the nonobese diabetic (NOD) mouse, an excellent model for human insulin-dependent diabetes mellitus (IDDM). We injected IL-10 expression plasmid (pCAGGS-IL10) or a control pCAGGS plasmid into the muscles of NOD mice twice at 3 and 5 weeks of age. IL-10 was detectable by ELISA in the sera of mice injected with pCAGGS-IL10 for more than 2 weeks after the injection. Although the severity of insulitis at 13 weeks of age was not improved by the intramuscular injection of pCAGGS-IL10, the incidence of diabetes was markedly reduced in NOD mice injected with pCAGGS-IL10 as compared with those injected with pCAGGS or as compared with nontreated NOD mice. These results show that the progression of autoimmune diseases in mice can effectively be suppressed by intramuscular DNA injection, and suggest that this method is potentially applicable to the treatment of human autoimmune diseases.

Animals↗
PubMed1998

Displacement of platelets from blood to spleen following intravenous injection of liposomes encapsulating dichloromethylene bisphosphonate.

Liposomes encapsulating dichloromethylene bisphosphonate (Cl2MBP-liposomes) have been shown to cause selective depletion of phagocytic macrophages. We have shown that intravenous injection of Cl2MBP-liposomes into mice induces an almost complete depletion of F4/80-positive cells (mature macrophages) in the liver and in the splenic red pulp, but not in the lung. Platelets in the mouse contain a large amount of 5-hydroxytryptamine (5HT; serotonin) and so, by measuring 5HT, it is possible to assess the translocation of platelets to tissues. The injection of Cl2MBP-liposomes was found to induce a prolonged and marked increase in 5HT that occurred selectively in the spleen. On the other hand, 5HT in the blood decreased by as much as 50%. These changes in 5HT corresponded well with each other in terms of both time course and dose-response relationship. To judge from measurements made at the peak of the response, the 5HT increase in the spleen corresponded to about 80% of the 5HT lost from the blood. Electron microscopic analysis revealed a great accumulation of platelets in the splenic cords. We have shown that aggregation and degranulation of platelets in the lung is involved in rapid anaphylactoid shock induced within 10 min of intravenous injection into mice of a lipopolysaccharide [Shibazaki, M., Nakamura, M., Endo, Y., 1996. Biphasic, organ-specific, and strain-specific accumulation of platelets induced in mice by a lipopolysaccharide from Escherichia coli and its possible involvement in shock. Infect. Immun. 64, 5290-5294; Endo, Y., Shibazaki, M., Nakamura, M., Takada, H., 1997. Contrasting effects of lipopolysaccharides (endotoxins) from oral black-pigmented bacteria and Enterobacteriaceae on platelets, a major source of serotonin, and on histamine-forming enzyme in mice. J. Infect. Dis. 175, 1404-1412]. In the present study, it was found that such shock was almost completely prevented in those mice in which platelets were displaced from the blood by Cl2MBP-liposomes. These results suggest that in the spleen the depletion of phagocytic macrophages may impair the function or structure of this organ. This may lead to the entry of platelets into the spleen in such large numbers as to reduce their level in the blood and result in their prolonged accumulation in the spleen. The Cl2MBP-liposome may be an excellent tool for the in vivo investigation of the role of platelets, as well as that of macrophages.

Analgesics, Non-Narcotic↗