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Biomedical subjects

M Harada

Publications and source records attributed to M Harada.

At least 163 records · Page 9Linked to original sources
PubMed2001

New graphics models for PC based ocular surgery simulator.

High-end graphics workstations (GWS) have been used for surgical simulators utilizing Computer Graphics (CG) and Virtual Reality (VR) technologies. This is because the simulators need lots of computing power, mainly for collision detection among objects modeled as a set of polygons. In this paper, we propose to use mathematical functions to model objects for collision detection. However, for graphic display we continue to use polygonal representation. Using the new model, we have developed a PC based ocular surgery simulator, which creates realistic surgery image in real-time. The computation time was found to be much lower than that in the conventional method.

Computer Graphics↗
PubMed2001

Compound heterozygosity for alpha-1-antitrypsin (S(iiyama) and QO(clayton)) in an Oriental patient.

Alpha-1-antitrypsin (alpha1AT) deficiency is extremely rare among Orientals. We treated a 37-year-old man with severe pulmonary emphysema associated with a low serum concentration of alpha1AT. Mutation analysis of the alpha1AT gene was performed using a reverse transcription-polymerase chain reaction followed by sequencing. The patient proved to be a compound heterozygote carrying a S(iiyama) deficient allele and a QO(clayton) null allele. This is the first Japanese case of alpha1AT deficiency to arise from such compound heterozygosity in a family with no apparent consanguineous marriage, suggesting that the gene frequency for deficient alleles might be somewhat higher than previously estimated.

Adult↗
PubMed2001

[Immunological properties of S-1090, cefmatilen hydrochloride hydrate].

S-1090, a cefmatilen hydrochloride hydrate, is being developed as a cephalosporin antibiotic for oral use. Immunogenicity, hypersensitivity-eliciting antigenicity and immunological cross-reactivity with other antibiotics were evaluated by active systemic anaphylaxis (ASA) test, passive cutaneous anaphylaxis (PCA) test and enzyme-linked immunosorbent assay (ELISA) using guinea pigs and mice/rats. In addition, in vitro direct Coombs' test was also performed to examine the possibility of hemolytic anemia in clinical use. Immunogenicity of S-1090 was not observed in guinea pigs after repeated immunization with S-1090 by ASA or PCA tests. Even in ELISA, only weak antibody production against S-1090 was found in some guinea pigs from the intraperitoneal groups showing the antibody titers only 10(1) to 10(2). When the sera collected from C3H/He mice and C57BL/6J mice immunized with S-1090 were tested for immunogenicity, rat PCA was elicited in a C3H/He mouse serum by S-1090 and antibodies against S-1090 were detected in a C57BL/6J mouse serum by ELISA. When adjuvant was used in mice and guinea pigs, the production of antibody against S-1090 was less frequent in comparison with other antibiotics such as cefmetazole (CMZ) and cefotiam (CTM). When hypersensitivity-eliciting antigenicity of S-1090 was examined using S-1090 as an eliciting antigen in ASA and PCA tests, positive ASA and PCA were observed in guinea pigs and positive PCA in a C3H/He mouse. Hypersensitivity-eliciting antigenicity was also observed in other reference antibiotics, i.e. cephalothin (CET), CMZ and CTM. Immunological cross-reactivity among S-1090, penicillin G (PCG), CET, CMZ and CTM was tested by ASA and PCA tests. S-1090 was found to immunologically cross-react only with CET in guinea pigs. In the present study, immunological cross-reactivities were also noted between PCG and CET, PCG and CMZ, PCG and CTM, and between CET and CMZ. In in vitro direct Coombs' test using human red blood cells, S-1090.Na, PCG and CET gave positive reactions at the final concentrations of 40 mg/mL, 20 to 40 mg/mL and 2.5 to 10 mg/mL, respectively.

Animals↗
PubMed2001

[Proton magnetic resonance spectroscopy of the autistic brain].

To evaluate brain dysfunction in autism, proton magnetic resonance spectroscopy (1H-MRS) was performed for 29 autistic patients (5-15 y.o.) and 19 normal children (6-14 y.o.). We obtained magnetic resonance (MR) spectra of the left and right amygdaloid-hippocampal regions and the left cerebellar hemisphere with a STEAM sequence (TR = 5000 ms, TE = 18 ms). In addition to the evaluation of signal intensity ratios, the absolute concentration of three major metabolites (N-acetylaspartate [NAA], creatine/phosphocreatine [Cr] and choline-containing substances [Cho]) was quantified by an internal reference method using unsuppressed tissue water. Although no abnormal MR images were found in the three regions examined, the signal intensity and the concentration of NAA in the left amygdaloid-hippocampal region and the left cerebellar hemisphere were reduced significantly in autistic patients compared to normal children. We speculated that this decrease in NAA reflected neuronal loss, immaturity or hypofunction in these regions. The results of our study were in agreement with those of previous studies on autism, one by neuropathological methods and the other using a single photon emission computed tomography with 99mTc HMPAO. Disorders of the amygdaloid-hippocampal region and cerebellum are considered to play an important role in the characteristic cognitive and emotional dysfunction in autism. 1H-MRS is a valuable tool to clarify the pathophysiology of autism.

Adolescent↗
PubMed2001

[An adult patient with varicella preceded by acute thrombocytopenia].

A 40-year-old man was admitted to our hospital because of a tendency to bleed. A diagnosis of idiopathic thrombocytopenic purpura was made, and oral prednisolone (1 mg/kg/day) was administered immediately. Three days after admission, hemorrhagic skin rashes highly suggestive of varicella appeared. The oral prednisolone was discontinued, and intravenous gamma-globulin (400 mg/kg/day for 3 days) and aciclovir (750 mg/day for 7 days) were started. The platelet count increased to 254,000/microliter over the next five days, and the skin rashes associated with varicella subsided within a week. We suggest that, in a minority of patients with varicella zoster infection, thrombocytopenia can precede the typical skin rashes, so a search for possible underlying viral infection should be made, and if necessary, immediate treatment started.

Acute Disease↗
PubMed2000

The heart is a source of circulating cardiotrophin-1 in humans.

Cardiotrophin-1 (CT-1) is a new member of the interleukin (IL)-6 family of cytokines and one of the endogenous ligands for gp130 signaling pathways in the heart, which has potent hypertrophic and survival effects on cardiac myocytes. However, the clinical significance of CT-1 is poorly understood, mainly because there is no widely applicable specific and sensitive assay system for measuring plasma levels of circulating CT-1. We therefore developed a competitive radioimmunoassay (RIA) for human CT-1 with rabbit antiserum recognizing the N-terminus region of human CT-1 and using recombinant human CT-1 as a calibrator. The assay displays no cross-reactivities with any of the IL-6 family of cytokines including IL-11, leukemia inhibitory factor, ciliary neurotrophic factor, and oncostatin M. The lower detection limit in buffer was found to be 43 fmol/ml, and the working range was 120-8300 fmol/ml (CV < 15%). This RIA directly recognizes CT-1-like immunoreactivity in human plasma with a mean value of 571 +/- 75 fmol/ml (mean +/- SD) in healthy volunteers. The RIA coupled with gel filtration chromatographic analyses showed that the major molecular form of circulating CT-1 corresponds to recombinant full-length human CT-1. Moreover, there is a significant increase in the plasma CT-1 concentration from the aorta and coronary sinus, which clearly indicates that the heart secretes CT-1 via the coronary sinus into the peripheral circulation. This RIA should serve as a powerful tool for investigating the clinical significance of CT-1.

Adult↗
PubMed2000

Macrophage-mediated activation of camptothecin analogue T-2513-carboxymethyl dextran conjugate (T-0128): possible cellular mechanism for antitumor activity.

Camptothecin (CPT) analogue T-2513-carboxymethyl (CM) dextran conjugate (T-0128) suppressed human tumor xenografts that were refractory to CPTs. This improvement was explained by its altered pharmacokinetics, but the cellular mechanism of action is still not clear. For this reason, in the present study we examined the determinants of T-0128 action at the cellular level. In vitro tests showed that T-0128 was inactive, indicating that the requirement for its activity lies in the release of linked T-2513, accompanied by the cellular uptake of the conjugate. The accumulation varied between cell lines: tumor cells, including Walker-256 carcinoma and B16 melanoma, showed only a marginal uptake and an undetectable drug release in the medium. In contrast, macrophage-like cells, such as J774.1, internalized T-0128 very efficiently, and liberated T-2513. With regard to the mode of accumulation, fluid-phase pinocytosis seems to be a key factor based on the followings: a similar cell-specificity existed in the uptake of FITC dextran, a marker of fluid-phase pinocytosis. Also, the macrophage uptake of T-0128 increased almost linearly with its medium concentration and was insensitive to dextran sulfate, a ligand for macrophage scavenger receptor. Comparative efficacy studies of T-0128 in the presence and absence of macrophages demonstrated that macrophages increased the efficacy of T-0128. The enhancement could be explained in terms of increases in the amount of released T-2513. Overall, these results lead us to the conclusion that T-0128 acts like a Trojan horse with the help of macrophages: T-0128 is taken up by macrophages in tumor tissues, and the liberated T-2513 kills tumor cells.

Animals↗
PubMed2000

Determinants for the drug release from T-0128, camptothecin analogue-carboxymethyl dextran conjugate.

To improve pharmacological profiles of camptothecins (CPTs), a new macromolecular prodrug, denoted T-0128, was synthesized. This prodrug comprises a novel CPT analog (T-2513: 7-ethyl-10-aminopropyloxy-CPT) bound to carboxymethyl (CM) dextran through a Gly-Gly-Gly linker, with a molecular weight of 130 kDa. The present study was designed to elucidate the mechanisms that promote the release of linked T-2513. First, we compared the abilities of a rat liver homogenate, a cocktail of its lysosomal enzymes, and different types of pure enzymes, to liberate T-2513 from the conjugate. The releasing rate in the homogenate was very slow, but was accelerated with the lysosomes. Lysosomal cysteine proteinases, such as cathepsin B, were responsible, coupled with the results of in vitro and in vivo inhibition studies using proteinase inhibitors. The pH optimum for the cathepsin B-mediated drug release was approximately 4. This corresponds to the pH in lysosomes, suggesting lysosomotropic release. Second, to assess the effect of the length and composition of the peptidyl linker, we synthesized the conjugates with a different linker and compared the drug-releasing rates. We found that the insertion of Phe into Gly-Gly-Gly allowed various kinds of enzymes to produce a rapid cleavage, and the Gly-chain lengthening enhanced the lysosome-mediated drug release. The released T-2513 levels in the liver and tumor of the tumor-bearing rats dosed with each conjugate increased with the length of Gly linker, suggesting a good in vitro to in vivo relationship. Comparative efficacy studies of the conjugates with a different linker demonstrated that T-0128 showed the maximum efficacy against MX-1 human mammary xenograft tumors. Thus the Gly-Gly-Gly linker exploits lysosomal cathepsin B to liberate T-2513 slowly and steadily, resulting in improved therapeutic efficacy.

Animals↗
PubMed2000

The effects of sarpogrelate on cardiomyocyte hypertrophy.

Sarpogrelate was developed as an antiplatelet agent antagonizing 5-hydroxytryptamine (5-HT) receptors. It had been reported that 5-HT receptors were expressed in cardiovascular system, and that sarpogrelate had antihypertrophic effects in vascular smooth muscle cells. Cardiac hypertrophy is a major problem in cardiac diseases, so the present study was designed to elucidate the effects of sarpogrelate on cardiac hypertrophy. Cultured rat cardiomyocytes (MCs) and cardiac nonmyocytes (NMCs) were prepared by Percoll gradient and adhesion method and MCs were incubated with (MCs/NMCs) or without NMCs. As an index of protein synthesis of MCs, [3H]-leucine uptake into MCs and MCs/NMCs was measured. Sarpogrelate decreased [3H]-leucine uptake into MCs (maximum 62.6+/-20.6% of control at 10(-4)M, p<0.05 vs. control). Sarpogrelate also significantly attenuated angiotensin-II- and endothelin-1-induced [3H]-leucine uptake. These results indicated that sarpogrelate might have antihypertrophic effects and could be a useful aid for cardiovascular disease.

Angiotensin II↗
PubMed2000

Replication protein A1 reduces transcription of the endothelial nitric oxide synthase gene containing a -786T-->C mutation associated with coronary spastic angina.

We recently reported that a mutation (-786T-->C) in the promoter region of the endothelial nitric oxide synthase (eNOS) gene reduced transcription of the gene and was strongly associated with coronary spastic angina and myocardial infarction. To elucidate the molecular mechanism for the reduced eNOS gene transcription, we have now purified a protein that specifically binds to the mutant allele in nuclear extracts from HeLa cells. The purified protein was identical to replication protein A1 (RPA1), known as a single-stranded DNA binding protein essential for DNA repair, replication and recombination. In human umbilical vein endothelial cells, inhibition of RPA1 expression using antisense oligonucleotide restored transcription driven by the mutated promoter sequence, whereas, conversely, overexpression of RPA1 further reduced it. RPA1 was similarly detected in placenta and eNOS mRNA levels in placentas carrying the -786T-->C mutation were significantly lower than in placentas without it. The functional importance of the diminished eNOS expression was revealed by the finding that serum nitrite/nitrate levels among individuals carrying the -786T-->C mutation were significantly lower than among those without the mutation. RPA1 thus apparently functions as a repressor protein in the -786T-->C mutation-related reduction of eNOS gene transcription associated with the development of coronary artery disease.

Alleles↗
PubMed2000

Copper does not alter the intracellular distribution of ATP7B, a copper-transporting ATPase.

Wilson's disease is a genetic disorder characterized by the accumulation of copper in the body due to a defect of biliary copper excretion. However, the mechanism of biliary copper excretion has not been fully clarified. We examined the effect of copper on the intracellular localization of the Wilson disease gene product (ATP7B) and green fluorescent protein (GFP)-tagged ATP7B in a human hepatoma cell line (Huh7). The intracellular organelles were visualized by fluorescence microscopy. GFP-ATP7B colocalized with late endosome markers, but not with endoplasmic reticulum, Golgi, or lysosome markers in both the steady and copper-loaded states. ATP7B mainly localized at the perinuclear regions in both states. These results suggest that the main localization of ATP7B is in the late endosomes in both the steady and copper-loaded states. ATP7B seems to translocate copper from the cytosol to the late endosomal lumen, thus participating in biliary copper excretion via lysosomes.

Adenosine Triphosphatases↗
PubMed2000

Cineradiographic motion analysis of normal lumbar spine during forward and backward flexion.

STUDY DESIGN: Motion characteristics of the lumbar spine in the sagittal plane were investigated in vivo using cineradiography. OBJECTIVES: To evaluate the differences in motion characteristics of the normal lumbar spine between forward and backward flexion. SUMMARY OF BACKGROUND DATA: Despite previous lumbar kinematic studies, differences in motion characteristics of the lumbar spine between forward and backward flexion remain unclear. METHODS: Cineradiographic motion analysis was performed in 10 asymptomatic healthy male volunteers for two different lumbar motions. The motions consisted of active forward flexion (from maximum extension to maximum flexion) and active backward flexion (from maximum flexion to maximum extension). Displacements of the anterior and posterior vertebral corners from L3/L4 to L5/S1 were measured continuously in reference to the local coordinate system. Parameters investigated were onset of segmental motion, velocity of segmental motion, and continuous motion profiles of the vertebral corners during the two different motions. RESULTS: During forward flexion, initial lumbar motion started stepwise from the upper level (L3/L4) to the lower levels with phase lags. Angular velocity at the onset of motion increased as the level descended. On the contrary, during backward flexion, initial motion started from the lower level (L5/S1) to the upper levels. There was no relation between velocity and spinal levels during backward flexion. Motion profiles of both anterior and posterior vertebral corners at L3/L4 and L4/L5 segments during forward flexion were similar to those during backward flexion. However, the motion profiles at L5/S1 segment during forward flexion were different from those during backward flexion. CONCLUSIONS: During forward flexion of the lumbar spine, initial motion started from upper segments to the lower segments with phase lags. During backward flexion, initial motion started from the lower segments to the upper segments. Motion profiles of the vertebral corners during forward flexion were similar to those during backward flexion at L3/L4 and L4/L5. The motion profiles at L5/S1 were different between both flexions.

Adult↗
PubMed2000

Dominant negative isoform of the Ikaros gene in patients with adult B-cell acute lymphoblastic leukemia.

Gene targeting studies in mice have shown that the transcription factor Ikaros plays an essential role in lymphoid development and as a tumor suppressor in T cells, whereas the related gene Aiolos functions as a tumor suppressor in B cells. We analyzed the expression levels of the Ikaros gene family, Ikaros and Aiolos, in human bone marrow samples from patients with adult acute lymphoblastic leukemia [ALL (n = 46; B-cell ALL = 41; T-cell ALL = 5)]. Overexpression of the dominant negative isoform of Ikaros gene Ik-6 was observed in 14 of 41 B-cell ALL patients by reverse transcription-PCR, and the results were confirmed by sequencing analysis and immunoblotting. None of the other dominant negative isoforms of the Ikaros gene were detected by reverse transcription-PCR analysis. Southern blotting analysis with PstI digestion revealed that those patients with the dominant negative isoform Ik-6 might have small mutations in the Ikaros locus. We did not detect any overexpression of dominant negative isoforms of Aiolos in adult ALL patients. These results suggest that Ikaros plays a key role in human B-cell malignancies through the dominant negative isoform Ik-6.

Adolescent↗
PubMed2000

Complete regression of xenografted human carcinomas by camptothecin analogue-carboxymethyl dextran conjugate (T-0128).

Clinically available camptothecins (CPTs), such as irinotecan (CPT-11) and topotecan, represent one of the most promising classes of antitumor agents, despite their toxicity. To improve their pharmacological profiles, a new macromolecular prodrug, denoted T-0128, was synthesized. This prodrug is a novel CPT analogue (T-2513)-carboxymethyl (CM) dextran conjugate via a triglycine spacer, with a molecular weight of Mr 130,000. This study was designed to test the concept that the rational design of a CPT-polymer conjugate would increase the efficacy of the parent drug. The in vivo antitumor study against Walker-256 carcinoma demonstrated that T-0128 was 10 times as active as T-2513, supporting this concept. Additionally, comparative efficacy studies of T-0128, T-2513, CPT-11, and topotecan were performed using a panel of human tumor xenografts in nude mice, showing the advantage of T-0128 over these CPTs. The maximal tolerated doses (MTDs) of T-0128, T-2513, and CPT-11 were comparable. Even a single i.v. injection of T-0128 at 6 mg/kg (based on the amount of T-2513 bound to CM dextran) induced complete regression of MX-1 mammary carcinoma. T-0128 at 10 mg/kg weekly for 3 weeks (one-tenth of its MTD) cured LX-1 lung carcinoma. Also, T-0128 below its MTD consistently cured or regressed St-4 gastric and HT-29 colorectal tumor xenografts that are highly refractory to CPTs. These demonstrate the broad range of therapeutic doses achieved with T-0128. Pharmacokinetic studies were performed to correlate the efficacy results obtained for T-0128 with plasma and tissue drug concentrations using Walker-256 tumor-bearing rats. Results showed that after i.v. administration of T-0128, the conjugate continued to circulate at a high concentration for an extended period, resulting in tumor accumulation. In the tumor, the sustained release of T-2513 occurred. In contrast, T-2513 disappeared rapidly from the body. The significant increases in the amount and exposure time of released T-2513 in the tumor explain well the enhanced efficacy of T-0128. In conclusion, this study indicated that T-0128 improved the potency of T-2513, demonstrating the proof of the above concept.

Animals↗
PubMed2000

Fluorescence in situ hybridization evaluation of c-myc and androgen receptor gene amplification and chromosomal anomalies in prostate cancer in Japanese patients.

BACKGROUND: Oncogene amplification and chromosomal anomalies are found in many solid tumors and are often associated with aggressiveness of cancer. We evaluated the frequency and the association of c-myc and androgen receptor (AR) gene amplification and gain of chromosome 8 or X in prostate cancer in Japanese patients. METHODS: We examined a total of 42 prostate cancer specimens, using fluorescence in situ hybridization (FISH). Dual-labeling hybridization with a directly labeled centromere probe for chromosome 8 or X together with a probe for the c-myc or AR locus was performed. RESULTS: Gain of chromosome 8 was identified in 54.8% of specimens and was associated with Gleason sum and nuclear anaplasia in untreated prostate cancers. c-myc gene amplification was found in 14.3% of specimens. Gain of chromosome X was identified in 42.9% of specimens. AR gene amplification was detected in 0 of 37 untreated prostate cancers, but in 1 of 5 hormone-refractory prostate cancers. CONCLUSIONS: Our results suggest that c-myc and AR gene amplification and gain of chromosome 8 or X may be associated with the development and progression of prostate cancers. These results obtained in Japanese cases are consistent with the results observed in prostate cancer in Western countries.

Chromosome Aberrations↗
PubMed2000

Involvement of decidual Valpha14 NKT cells in abortion.

The immunological mechanisms that regulate abortion are largely unknown. Here, we found that a distinct subset of lymphocytes, Valpha14 NKT cells expressing an invariant antigen receptor encoded by Valpha14/Jalpha281 and Vbeta7 segments, accumulated in the decidua during pregnancy and provoked abortion upon stimulation with alpha-galactosylceramide (alpha-GalCer), a specific ligand for Valpha14 NKT cells. The alpha-GalCer-mediated abortion was not observed in Valpha14 NKT-, IFN-gamma-, tumor necrosis factor alpha-, or perforin-knock-out mice and appeared to be due to the degeneration of embryonic trophoblasts mediated by the activated Valpha14 NKT cells whose perforin-dependent killing and production of IFN-gamma and tumor necrosis factor alpha were essential. The possible role of the decidual Valpha14 NKT cells in the pathogenesis of abortion is discussed.

Abortion, Induced↗