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Biomedical subjects

T Hara

Publications and source records attributed to T Hara.

At least 451 records · Page 25Linked to original sources
PubMed1998

The application of molecular biological tools to epidemiology of African trypanosomosis.

Difficulties have often been encountered in the field surveys due to a lack of definitive morphological characters, particularly where mixed infections are expected. To address this problem, some molecular biological techniques such as DNA probe hybridization, restriction fragment length polymorphism (RFLP) analysis, the polymerase chain reaction (PCR), analyses of ribosomal DNA, and pulsed-field gel electrophoresis (PFGE), have been applied to the analysis of field samples collected during epidemiological surveys of African trypanosomosis. Concurrent natural infection of different individual tsetse flies and mammalian hosts with different species of the trypanosomes have been demonstrated, through the use of a combination of specific DNA probe hybridization and the PCR. Molecular karyotypes of Trypanosoma brucei species were analyzed by PFGE in 45 - 2,000 kb range. There are distinctive differences in intermediate and mini-chromosomes among the strains. We have compared the nucleotide sequences of ribosomal DNAs of the parasites by PCR techniques. From this data new phylogenetic tree can be inferred. It is apparent that these technologies can provide powerful tools for identification and diagnosis of trypanosomes in their hosts and vectors, and for their more accurate phylogenetic classification.

Animals↗
PubMed1998

[The cytotoxic effect of topical mitomycin C on the ciliary body in rabbits].

We evaluated the cytotoxic effects of mitomycin C (MMC) in rabbit eyes. A sponge soaked with MMC was placed on the bared sclera after conjunctival incision. We used four concentrations of MMC in distilled water: 0%, 0.04%, 0.1%, and 0.4%. MMC was applied to one eye only, with the fellow eye serving as control. The eyes were studied for intraocular pressure (IOP) and by fluorophotometry at 3, 7, 14, and 28 days of treatment. Eyes treated with 0.04% and 0.4% MMC were studied histologically at 3 and 28 days. All the MMC-treated eyes showed no significant changes regarding IOP (56 eyes) or fluorophotometric features (28 eyes) regarding aqueous humor dynamics and blood-aqueous barrier. Pathologic changes of the ciliary epithelium, including intracellular vacuoles and swelling of mitochondria, were more pronounced in eyes treated with 0.4% MMC than those treated with 0.04%. These changes were more manifest in areas inner to the site of application than in the opposite area. Topical application of 0.04% MMC thus showed no evident toxic effects on the function of the ciliary body and other pathological changes were minor.

Administration, Topical↗
PubMed1998

[Clear cell ependymoma--a case report].

A case of intraaxial clear cell ependymoma is reported. A 46-year-old man complained of right hemiparesis. CT scan showed a mass lesion on the median plane with a huge cyst in the left frontal lobe. MRI showed an iso-low intensity mass by T1-weighted image. The tumor was heterogeneously enhanced by Gd-DTPA and the wall was enhanced as well. Angiogram revealed a tumor stain from the right internal carotid artery. The main mass of the tumor was totally removed but the cystic wall was left removed. Histopathological examination revealed clear cell ependymoma. Immunohistochemical examination revealed that, although vimentin and NSE were positive, GFAP, synaptophysin and S-100 were negative. Ultrastructual examination revealed cilia, microvilli and desmosomal junctions. The patient fully recovered after operation and showed no sign of recurrence after an year of follow-up. Clear cell ependymoma is a rare variant of ependymoma. Ultrastructual examination was more useful than immunohistochemical examination for diagnosis.

Brain Neoplasms↗
PubMed1998

PET imaging of prostate cancer using carbon-11-choline.

UNLABELLED: Prostate cancer is difficult to visualize using current techniques. Recently, 31P magnetic resonance spectroscopy has revealed that the tumor, in general, is characterized by an increased uptake of choline into the cell to meet increased synthesis of phosphatidylcholine, an important cell membrane phospholipid. We succeeded in using 11C-choline to visualize prostate cancer and its local metastasis in PET. METHODS: PET was performed on 10 prostate cancer patients from the level of pelvis to the lower abdomen. After transmission scanning, 370 MBq 11C-choline were injected intravenously. The emission scan was performed 5-15 min postinjection. Finally, PET images were displayed so that each pixel was painted by a specified color representing the degree of the standardized uptake value (SUV). The 11C-choline image was compared with the 18F-fluorodeoxyglucose (FDG) image obtained from the same patient. RESULTS: Imaging of prostate cancer and its local metastasis was difficult when 18F-FDG was used because, within the pelvis, the areas of high uptake were concealed by the overwhelmingly abundant radioactivity in urine (in ureters and bladder). By contrast, it was easy when 11C-choline was used because the urinary activity was negligible and tumor uptake was marked. The radioactivity concentration of 11C-choline in prostate cancer and metastatic sites was at an SUV of more than three in most cases. The SUV of 18F-FDG was considerably lower than that of 11C-choline. CONCLUSION: Prostate cancer and its local metastasis were visualized clearly in PET using 11C-choline.

Adenocarcinoma↗
PubMed1998

Mechanical properties of buccal compact bone of the mandibular ramus in human adults and children: relationship of the elastic modulus to the direction of the osteon and the porosity ratio.

With recent advances in computers, the finite element method has been used for stress analysis of bone. In particular, the dynamic behavior of the jaw bone has been a subject of interest and analyzed by this method. However as the elastic modulus needed for this method, a uniform value is used without considering differences according to site or direction. Therefore, we measured the elastic modulus at various sites and in various directions of the mandible in adults and children. In addition, the association between the elastic modulus and histological structures was evaluated. Ten specimens of dried mandible from human adults and children were used. The elastic modulus was measured in two regions prepared by equally dividing the ramus of the mandible into lower and upper regions. Samples of 6 mm x 960 microns x 425 microns were collected from the buccal compact bone. The elastic modulus was measured using a three-point bending test. After measurement, the direction of the osteon was examined using SEM. The porosity ratio was also measured after CMR were taken. In both adults and children, anisotropy in the elastic modulus of each direction in the upper region was similar to the anisotropy in unidirectional fiber reinforced composite materials, but not in the lower region. The elastic modulus decreased slightly with an increase in the angle of the direction of osteons to the longitudinal axis of specimens. The direction of osteon may significantly influence anisotropy in the elastic modulus. The elastic modulus in adults was higher than in children in all directions. The porosity ratio in adults was smaller than that in children in all directions. The difference in the porosity ratio between adults and children may significantly influence the value of the elastic modulus.

Adult↗
PubMed1998

[Ocular tissue concentrations and results of filtration surgery after topical use of mitomycin C in rabbits].

We measured mitomycin C (MMC) concentrations in rabbit ocular tissues, using high-performance liquid chromatography, after the subconjunctival application of surgical sponges which had absorbed various doses (0.1, 0.2 or 0.4 mg) of MMC and with varying duration of application (1, 3, or 5 minutes). MMC concentrations at the administered site showed a significant correlation with the dose and duration of application. In multiple regression analysis the MMC concentration (microgram/g) in the conjunctiva was -6.73 + 67.4 x dose (mg) + 1.66 x time (minutes) (R-square 0.65); in the sclera, -1.85 + 38.2 x dose + 0.927 x time (R-square 0.63); and in the corena, -0.727 + 8.44 x dose (R-square 0.46). We also compared the results of filtering surgery on rabbits using 0.2 mg MMC intraoperative exposure of 1, 3, 5 minutes or 5-minute application of distilled water (control). The duration of maintained intraocular pressure reduction and filtering bleb was significantly longer in MMC-treated group (1 minute; 15 +/- 7.1, 3 minutes; 27 +/- 14.3, 5 minutes; 29 +/- 18.6 days, mean +/- standard deviation) than in the control group (7 +/- 3.7 days). Among the MMC-treated groups, good results were maintained significantly longer in the 3- or 5-minute application groups than in the 1-minute group. There was no difference between the 3-minute group and the 5-minute group.

Animals↗
PubMed1998

Amplification of c-myc, K-sam, and c-met in gastric cancers: detection by fluorescence in situ hybridization.

Gene amplifications of c-myc, K-sam, and c-met were examined in cancer nuclei isolated from 154 primary gastric adenocarcinomas by fluorescence in situ hybridization (FISH) using cosmid probes for 8q24 (c-myc locus) and 7q31 (c-met), as well as a DNA probe for K-sam synthesized by PCR. The results were compared with those of Southern blot analysis. Dual-color FISH using gene locus and chromosome-specific probes detected gene amplifications of c-myc in 24 tumors (15.5%), c-met in 6 tumors (3.9%), and K-sam in 3 tumors (2.9%). The six tumors with c-myc amplification had also been found to have amplified c-erbB-2 in our previous study, and coamplification of c-myc and c-met was found in two other tumors. This technique also differentiated the amplified genes on the homogeneous staining region (HSR) and on double minute chromosomes (DMs) in metaphase spreads and interphase nuclei of cell lines established from poorly differentiated adenocarcinomas, KATO III, SNU 16, and HSC 39. Examination of FISH images of these cell lines suggested that the high-level amplifications of c-myc found in primary tumors occurred mainly on DM in four tumors and on HSR in one, and those of K-sam occured on DM in two tumors and on HSR in one. No high-level amplification of c-met was found. These high-level amplifications were also detected in formalin-fixed, paraffin-embedded tissues from primary gastric tumors and metastatic lymph nodes, in some of which heterogeneity of gene amplification was demonstrated within the same tumor. We conclude that FISH is an important tool for examining the proto-oncogene aberrations in intact cells in solid tumors.

Blotting, Southern↗
PubMed1998

[A case report of cavernous hemangioma of the left atrial epicardium].

Cardiac hemangioma is a rare benign vascular tumor. A 44-year-old woman with hemangioma arising from the left atrium and transient atrial fibrillation is reported. Echocardiography, computed tomography and magnetic resonance imaging suggested a hypervascular tumor with clear borders in the pericardial cavity. Selective coronary angiography demonstrated feeding arteries arising from the right and left circumflex coronary arteries. Under cardiopulmonary bypass the tumor was successfully resected. Pathological examination showed a cavernous hemangioma. There is no evidence of recurrence and the patient is doing well three years after the operation.

Adult↗
PubMed1998

Polyol pathway hyperactivity is closely related to carnitine deficiency in the pathogenesis of diabetic neuropathy of streptozotocin-diabetic rats.

To investigate the relationship between polyol pathway hyperactivity and altered carnitine metabolism in the pathogenesis of diabetic neuropathy, the effects of an aldose reductase inhibitor, [5-(3-thienyl) tetrazol-1-yl]acetic acid (TAT), and a carnitine analog, acetyl-L-carnitine (ALC), on neural functions and biochemistry and hemodynamic factors were compared in streptozotocin-diabetic rats. Significantly delayed motor nerve conduction velocity, decreased R-R interval variation, reduced sciatic nerve blood flow and decreased erythrocyte 2, 3-diphosphoglycerate concentrations in diabetic rats were all ameliorated by treatment with TAT (administered with rat chow containing 0.05% TAT, approximately 50 mg/kg/day) or ALC (by gavage, 300 mg/kg/day) for 4 weeks. Platelet hyperaggregation activity in diabetic rats was diminished by TAT but not by ALC. TAT decreased sorbitol accumulation and prevented not only myo-inositol depletion but also free-carnitine deficiency in diabetic nerves. On the other hand, ALC also increased the myo-inositol as well as the free-carnitine content without affecting the sorbitol content. These observations suggest that there is a close relationship between increased polyol pathway activity and carnitine deficiency in the development of diabetic neuropathy and that an aldose reductase inhibitor, TAT, and a carnitine analog, ALC, have therapeutic potential for the treatment of diabetic neuropathy.

Acetylcarnitine↗
PubMed1998

[Cytarabine-induced pericarditis].

We report two cases of cytarabine (Ara-C) induced pericarditis. The first patient was a 61-year-old man with de novo acute myelogenous leukemia (AML) with trilineage myelodysplasia (M2). Fever and pericardial effusion developed after treatment with low-dose Ara-C and etoposide (VP16) during the patient's second leukemic relapse. The second patient was a 65-year-old man with myelodysplastic syndrome (MDS) transformed into AML (M2). He achieved a complete remission after treatment with low-dose Ara-C and VP16. However, during consolidation chemotherapy consisting of oral cytarabine ocfosfate and VP16, fever and pericardial effusion developed. In both cases, pericardiocentesis revealed exudative effusion with many neutrophils. Neither bacterial nor fungal infection was demonstrated. Chest symptoms and fever were resolved by methylprednisolone pulse therapy and pericardial drainage. Both patients were given a diagnosis of pericarditis caused by allergic reaction to Ara-C. We also report on 6 other patients with Ara-C syndrome who have been encountered by our hospital.

Aged↗
PubMed1998

Fracture risk during pedicle screw insertion in osteoporotic spine.

Although using a larger screw can enhance the stability of screw-bone interface in pedicular screw instrumentation, it may cause pedicle fracture during screw insertion in osteoporotic spine. We investigated structural changes of the pedicle with the advance of osteoporosis and its implication for the risk of pedicle fracture. Bone mineral density of trabecular, subcortical, and cortical bone of pedicle in an osteoporotic group, assessed by peripheral quantitative computed tomography, was significantly lower than that of those in the normal group. Cortical thickness also declined. There were no pedicle fractures in normal vertebrae, but seven (41.2%) fractures were observed among 17 pedicles in osteoporotic vertebrae in which bone mineral density measured with dual-energy x-ray absorptiometry was <0.7 g/cm2 and screw diameter >70% of the outer diameter of the pedicle. Our results suggest that screw diameter should not exceed 70% of the outer diameter of the pedicle in the case of osteoporosis in which vertebral bone mineral density is <0.7 g/cm2.

Aged↗
PubMed1997

In vivo gene delivery to the liver using reconstituted chylomicron remnants as a novel nonviral vector.

Lipoproteins are emulsion particles that consist of lipids and apolipoproteins. Their natural function is to transport lipids and/or cholesterol to different tissues. We have taken advantage of the hydrophobic interior of these natural emulsions to solubilize DNA. Negatively charged DNA was first complexed with cationic lipids containing a quaternary amine head group. The resulting hydrophobic complex was extracted by chloroform and then incorporated into reconstituted chylomicron remnant particles ( approximately 100 nm in diameter) with an efficiency approximately 65%. When injected into the portal vein of mice, there were approximately 5 ng of a transgene product (luciferase) produced per mg of liver protein per 100 microg injected DNA. This level of transgene expression was approximately 100-fold higher than that of mice injected with naked DNA. However, such a high expression was not found after tail vein injection. Histochemical examination revealed that a large number of parenchymal cells and other types of cells in the liver expressed the transgene. Gene expression in the liver increased with increasing injected dose, and was nearly saturated with 50 microg DNA. At this dose, the expression was kept at high level in the liver for 2 days and then gradually reduced and almost disappeared by 7 days. However, by additional injection at day 7, gene expression in the liver was completely restored. By injection of plasmid DNA encoding human alpha1-antitrypsin, significant concentrations of hAAT were detected in the serum of injected animals. This is the first nonviral vector that resembles a natural lipoprotein carrier.

Animals↗
PubMed1997

Characterization, sequencing, and expression of the genes encoding a reactivating factor for glycerol-inactivated adenosylcobalamin-dependent diol dehydratase.

Diol dehydratase undergoes suicide inactivation by glycerol during catalysis involving irreversible cleavage of the Co-C bond of adenosylcobalamin. In permeabilized Klebsiella oxytoca and Klebsiella pneumoniae cells, the glycerol-inactivated holoenzyme or the enzyme-cyanocobalamin complex is rapidly activated by the exchange of the inactivated coenzyme or cyanocobalamin for free adenosylcobalamin in the presence of ATP and Mg2+ (Honda, S., Toraya, T., and Fukui, S. (1980) J. Bacteriol. 143, 1458-1465; Ushio, K., Honda, S., Toraya, T., and Fukui, S. (1982) J. Nutr. Sci. Vitaminol. 28, 225-236). Permeabilized Escherichia coli cells co-expressing the diol dehydratase genes with two open reading frames in the 3'-flanking region were capable of reactivating glycerol-inactivated diol dehydratase as well as activating the enzyme-cyanocobalamin complex in situ in the presence of free adenosylcobalamin, ATP, and Mg2+. These open reading frames, designated as ddrA and ddrB genes, were identified as the genes of a putative reactivating factor for inactivated diol dehydratase. The genes encoded polypeptides consisting of 610 and 125 amino acid residues with predicted molecular weights of 64,266 and 13,620, respectively. Co-expression of the open reading frame in the 5'-flanking region was stimulatory but not obligatory for conferring the reactivating activity upon E. coli. Thus, the product of this gene was considered not an essential component of the reactivating factor.

Amino Acid Sequence↗
PubMed1997

A mammalian homolog of the yeast LCB1 encodes a component of serine palmitoyltransferase, the enzyme catalyzing the first step in sphingolipid synthesis.

Serine palmitoyltransferase (SPT; EC 2.3.1.50) catalyzes the initial step dedicated to sphingolipid biosynthesis and is thought to be a key enzyme for regulating cellular sphingolipid content. For SPT activity, the yeast Saccharomyces cerevisiae requires two genes, LCB1 and LCB2. We isolated mammalian LCB1 cDNA homologs from mouse and Chinese hamster ovary (CHO) cells and an LCB2 cDNA homolog from CHO cells. The mammalian LCB1 proteins are predicted to have about 35% amino acid identity to the yeast Lcb1 protein, whereas the CHO LCB2 protein is predicted to have about 40% amino acid identity to the yeast Lcb2 protein. Northern blot analysis of mRNA isolated from various mouse tissues revealed that the tissue distribution of both LCB1 and LCB2 messengers followed a similar pattern. Transfection of an SPT-defective CHO mutant strain with a CHO LCB1-expressing plasmid restored both SPT activity and de novo sphingolipid synthesis to the wild type levels, whereas transfection of the mutant strain with a CHO LCB2-expressing plasmid did not exhibit any recovery effects, indicating that the SPT defect in the mutant cells is specifically complemented by the CHO LCB1 homolog. Furthermore, when the SPT-defective mutant cells were transfected with a plasmid encoding a His6-tagged CHO LCB1 protein, SPT activity bound to a Ni2+-immobilized resin. These results indicate that the CHO LCB1 homolog encodes a component of SPT.

Acyltransferases↗
PubMed1997

Structural characteristics of the pedicle and its role in screw stability.

STUDY DESIGN: Cross-sectional regional bone mineral density of the pedicle was measured by peripheral quantitative computed tomography. Biomechanical tests were performed to clarify the role of the pedicle in screw stability. OBJECTIVES: To identify the structural characteristics of the pedicle that supports pedicle screw stability and the differences in these characteristics between normal and osteoporotic vertebrae. SUMMARY OF BACKGROUND DATA: The pedicle screw is an essential component of many systems used to align the spine. The contribution of the pedicle to screw stability, however, has not been fully investigated. METHODS: Trabecular, subcortical, and cortical bone mineral density and the area of the pedicle were measured by peripheral quantitative computed tomography. Bone mineral density also was recalculated in four circumferential layers. These parameters were compared between normal and osteoporotic individuals. The relative contribution of the pedicle to screw stability was evaluated by caudocephalad and pull-out loading in a vertebra with or without its body. RESULTS: Inner trabecular, middle subcortical, and outer cortical bone mineral density and cortical bone area in the pedicle were significantly lower in osteoporotic vertebrae than those in normal vertebrae. In the pedicle, bone mineral density increased close to the outer layer. Bone mineral density not as thick even in the outer layer in osteoporotic subjects. Approximately 80% of the caudocephalad stiffness and 60% of the pullout strength of the pedicle screw depended on the pedicle rather than on the vertebral body. CONCLUSION: Screw stability depends on the structural characteristics of the pedicle. The pedicle was denser in the subcortical bone, in which the threads of the screw engage, than in trabecular bone. In osteoporosis, bone mineral density was not as dense even in the outer layer, and the cortex was thinner than normal. A larger screw would not enhance screw stability and may break the thin cortex in osteoporotic vertebrae.

Absorptiometry, Photon↗
PubMed1997

Regulation of tissue inhibitor of metalloproteinase-1 in fibroblasts and acute phase proteins in hepatocytes in vitro by mouse oncostatin M, cardiotrophin-1, and IL-6.

Mouse oncostatin M (mOSM) has been recently cloned; however, its full spectrum of biologic functions has not been defined. To assess its potential role in inflammation, we have tested the activity of mOSM in vitro in regulation of fibroblasts and hepatic cells. At concentrations of 10 and 20 ng/ml, mOSM stimulates tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA in NIH-3T3 mouse embryonic fibroblasts, rat lung fibroblasts, and rat synovial fibroblasts, whereas mouse cardiotrophin-1 (mCT-1) or human OSM (hOSM) did not. Similarly, only mOSM was able to induce transcription of chloramphenicol acetyl-transferase (CAT) in NIH-3T3 cells transfected with a minimal TIMP-1 promoter/CAT construct. Mouse OSM had strong action inducing primary rat hepatocyte cultures to produce acute phase proteins; however, mOSM was very weak in its ability to stimulate acute phase protein synthesis in rat H35 cells or human HepG2 cells, which was consistent with weak STAT activation in H35 cells and HepG2 cells. Binding studies showed that NIH-3T3 cells possessed high affinity binding sites for mOSM, but rat H35 cells did not. On the other hand, mCT-1 and mouse IL-6 induced strong STAT activation as well as marked increases in acute phase protein production by H35 cells. These results indicate that mOSM does not share a functional receptor with mCT-1 or hOSM in mouse and rat cells and that hOSM does not activate the putatively specific OSM receptor on mouse or rat cells. These results also suggest that mOSM is an important cytokine in inflammation, through modulation of fibroblast function as well as hepatocyte responses.

3T3 Cells↗
PubMed1997

Oncostatin M and leukemia inhibitory factor do not use the same functional receptor in mice.

Oncostatin M (OSM) and leukemia inhibitory factor (LIF) are members of the interleukin-6 (IL-6) subfamily of cytokines that use a common signal transducer gp130. Human OSM (hOSM) and LIF share a functional high-affinity receptor that is composed of gp130 and LIF receptor beta subunit (LIFRbeta). A second high-affinity receptor for hOSM was recently found to be formed by gp130 and the hOSM receptor beta subunit. However, the nature of murine OSM (mOSM) and its receptors has remained unknown. Using the recently cloned mOSM cDNA, we produced recombinant mOSM and studied its biological activity and receptor structure. Murine hematopoietic cell lines M1 and DA1.a, an embryonic stem cell line CCE, and Ba/F3 transfectants expressing gp130 and LIFRbeta responded to murine LIF (mLIF) and hOSM equally well, while these cells responded to mOSM only at a 30-fold to 100-fold higher concentration than those of mLIF and hOSM. In contrast, NIH3T3 cells responded to mOSM, but not to mLIF and hOSM. Scatchard plot analyses showed that mOSM bound to gp130 with low-affinity (kd = 2.8 to 4.2 nmol/L) and that the binding affinity did not increase in the presence of LIFRbeta. However, mOSM bound to NIH3T3 cells with high-affinity (kd = 660 pmol/L), whereas mLIF did not bind to NIH3T3 cells at all. These results indicate that unlike hOSM, mOSM and mLIF do not share the same functional receptor, and mOSM delivers signals only through its specific receptor complex. Further studies in mice will define the physiological roles of OSM.

Animals↗