Biomedical subjects
Publications and source records attributed to M Hirano.
A yeast two-hybrid screen of a chicken gizzard cDNA library detected the interaction of the catalytic subunit of protein phosphatase type 1 with a novel subunit. Subsequent characterization established similarity (58%) to the rat liver glycogen-binding subunit. Northern analyses showed expression in a wide range of tissues.
We characterized the GTP cyclohydrolase I (GTP-CH-I) gene in a patient with hereditary progressive dystonia with marked diurnal fluctuation/dopa-responsive dystonia (HPD/DRD). The sequence analysis revealed a C to A transversion, which predicts a novel missense mutation (Thr186Lys). Unexpectedly, this base change, occurring in the middle of exon 5, resulted in a production of the novel transcript lacking exon 5 and a part of exon 6. Three different transcripts of the GTP-CH-I gene, previously reported in the human liver, were also present in the peripheral lymphocytes from the patient and controls. Quantitative comparison of the truncated-subunit mRNA and the wild-type one implied that differential splicing regulates the GTP-CH-I enzyme activity, leading to the clinical variations in HPD/DRD. The patient showed a unique clinical symptom, suggesting that the nigrostriatal dopaminergic system is more affected than previously thought in HPD/DRD.
We report here purification and characterization of chromosome condensation protein complexes (termed condensins) containing XCAP-C and XCAP-E, two Xenopus members of the SMC family. Sucrose density gradient centrifugation reveals two major forms of condensins. The 8S form is a heterodimer of XCAP-C and XCAP-E, whereas the 13S form contains three additional subunits. One of them is identified as a homolog of the Drosophila Barren protein whose mutation shows a defect in chromosome segregation. Chromosomal targeting of condensins is mitosis-specific and is independent of topoisomerase IIalpha. 13S condensin is required for condensation, as demonstrated by immunodepletion and rescue experiments. Our results suggest that the condensin complexes represent the most abundant structural components of mitotic chromosomes and play a central role in driving chromosome condensation.
We identified large-scale heteroplasmic mitochondrial DNA (mtDNA) rearrangements in a 50-year-old woman with an adult-onset progressive myopathy. The predominant mtDNA abnormality was a 21.2-kb duplicated molecule. In addition, a small population of the corresponding partially deleted 4.6-kb molecule was detected. Skeletal muscle histology revealed fibers that were negative for cytochrome c oxidase (COX) activity and had reduced mtDNA-encoded COX subunits. By single-fiber polymerase chain reaction analysis, COX-negative fibers contained a low number of wild-type or duplicated mtDNA molecules (ie, nondeleted). In situ hybridization demonstrated that the abnormal fibers contained increased amounts of mtDNA compared with normal fibers and that most of the genomes were deleted. We concluded that deleted mtDNA molecules were primarily responsible for the phenotype in this patient.
alpha-Tricalcium phosphate (alpha-TCP)/dicalcium phosphate dibasic (DCPD)/tetracalcium phosphate monoxide (TeCP) cement was implanted in paste form into soft tissue (rate subcutaneous sockets) and bone tissue (defects in rabbit mandibles) to evaluate the setting behaviour of the cement and tissue responses to the cement. A histological study of the soft tissue implants revealed thin fibrous capsule formation, the appearance of multinucleated giant cells on and close to the cement surface, and small clusters of the cement near the main part of the set cement which were formed by the migration of the paste while setting. X-ray diffraction (XRD) analysis of the implanted cement showed peaks for hydroxyapatite (HA) which increased as the implant period increased. Histology and microradiography of the bone tissue implants showed well-set cement without migration, active bone formation around the cement and direct bone union to it. However, the cement disappeared from the implant site in 4 of 16 specimens where intense bleeding seemed to wash away the implants while setting. From the results of the present study, we concluded that the cement is well tolerated, especially by bone tissue. This may be related to the fact that the cement sets producing HA. The cement is a promising material as a bone substitute; however, there is a problem of migration while setting in soft tissue and of exclusion from the bone defects by intense bleeding.
Prehardened calcium phosphate cement consisting of alpha-tricalcium phosphate (alpha-TCP), dicalcium phosphate dibasic (DCPD) and tetracalcium phosphate monoxide (TeCP) was implanted in rabbit mandibles and back muscles, and studied histologically and microradiographically. In the mandibles, new bone formation occurred around the implants and increased in quantity the longer the implant period lasted. Histology, microradiography and scanning electron microscopy (SEM) demonstrated direct contact of bone and cement. Bone response to this cement was essentially the same as to hydroxyapatite (HA) ceramics, known as a biocompatible bone substitute. Material resorption was recognized, which increased with the implant period and was greater in the surface bound by soft tissue than the surface bound by bone tissue. In the back muscles, however, no calcified tissue formation occurred. Resorption proved to be faster than in the case of the mandible implants. It was concluded that the cement, in prehardened form, has good biocompatibility and is a promising material as a bone substitute.
We investigated the effect of chlorpromazine (CPZ) in a murine model of T-cell-dependent liver injury caused by concanavalin A (ConA). CPZ (3 and 10 mg/kg) treatment 1 h before ConA injection prevented liver injury. CPZ (3, 10 mg/kg) administered 1 h after a ConA injection was also hepatoprotective, whereas cyclosporin (CsA, 100 mg/kg) was active only when given before ConA. Under either condition, CsA but not CPZ prevented concurrent increases in splenic ornithine decarboxylase (ODC) activity, a putative index of T-cell proliferation/differentiation. CPZ down-regulated tumor necrosis factor-alpha (TNF-alpha) and up-regulated IL-10 in mice that then received ConA, whereas delayed administration of CPZ had no effect. These results suggest that CPZ prevented liver injury without affecting the proliferation/differentiation of T-cells. The dissociation of hepatoprotection by CPZ from cytokine modulation indicates that this drug intervenes in the adherence of T-cells or the death of hepatocytes in the ConA-model.
We investigated the effects of [pGlu4,Cyt6]AVP(4-9) fragments and its analogues on cycloheximide (CHX)-induced learning impairment in rats using the step-through-type passive avoidance test in rats. CHX (2.8 mg/kg, s.c.) significantly shortened the step-through latency in the retention trial. pGlu-Asn-Cys(Cys)-Pro-Arg-Gly-NH2 ([pGlu4, Cyt6]AVP(4-9); 10 ng/kg, s.c.), a major metabolite of arginine vasopressin, improved the CHX-induced learning impairment. Asn-Cys-Pro-Arg-OH ([Cys6]AVP(5-8); 1 ng/kg) corrected avoidance learning in the CHX-treated group, whereas neither Cys(Cys)-Pro-Arg-OH nor pGlu-Asn-Cys(Cys)-Pro-OH had any effect (1, 10 and 100 ng/kg, s.c.). pGlu-Asn-Ser-Pro-Arg-Gly-NH2 (No. 302), a newly synthesized [pGlu4,Cyt6]AVP(4-9) analogue, significantly prolonged the latency shortened by CHX at doses of 0.1, 1 and 10 ng/kg (s.c.). Asn-Ser-Pro-Arg-OH also improved the learning disruption induced by CHX, although the effective dose was 100 times higher than that of No. 302. The half-life of No. 302 in rat blood was about 5.5, 22 and 25 times longer than that of [pGlu4,Cyt6]AVP(4-9), [Cys6]AVP(5-8) and Asn-Ser-Pro-Arg-OH, respectively. These results suggest that [Cys6]AVP(5-8) is the minimal effective amino acid sequence in [pGlu4,Cyt6]AVP(4-9), and show that No. 302 is a potent, pharmacologically active peptide with high stability in the blood.
Progressive external ophthalmoplegia comprises many different disorders. Those of childhood onset can be separated from juvenile or adult onset. Among those of later onset the most common causes are oculopharyngeal muscular dystrophy, oculopharyngodistal muscular dystrophy and the several mitochondrial disorders, especially those with large deletions of mitochondrial DNA (mtDNA) (sporadic), those with maternal inheritance (point mutations), or the autosomal dominant forms with multiple deletions of mtDNA. Ophthalmoplegia of presumably neurogenic origin is seen in some of the familial spinocerebellar ataxias. Advances in molecular genetics should provide information about affected gene products and, therefore, pathogenesis.
The response of human acute myelogenous leukemia (AML) cells to four different hematopoietic growth factors (granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 beta (IL-1beta), interleukin-3 (IL-3), and stem cell factor (SCF)) and the relationship of the proliferative response of the AML cells to treatment outcome were studied. Proliferative responses were analyzed in 79 patients with de novo AML and 19 patients with AML arising from myelodysplastic syndrome (MDS). In de novo AML, a positive proliferative response (stimulation index >2) was seen in 65 to 75% of cases. AML cells arising from MDS had a much higher incidence of proliferative response to each growth factor (79 to 90%) and a much higher level of 3H-TdR incorporation. The relationship to treatment outcome was evaluated in 79 patients with de novo AML. The patients whose leukemic cells had a positive proliferative response to any growth factor, especially IL-3 and SCF, had a poorer outcome, ie a lower complete remission (CR) rate, shorter CR duration, and shorter survival. The outcome was particularly poor in patients whose leukemic cells had proliferative responses to all four or any of the growth factors, compared to patients whose leukemic cells had no response. This increased response may be a marker of poor prognosis in patients with AML.
The term junctional scotoma of Traquair is used to describe a unilateral temporal visual field defect due to pathology of the ipsilateral optic nerve where it joins the chiasm. We report a 26-year-old woman who presented with blurred vision of her left eye. Examination revealed visual acuity of 20/20 OU, AO-HRR color plates 6/6 OD and 4.5/6 OS, and a 0.3 log unit relative afferent pupillary defect on the left side. Computer and Goldmann perimetry revealed a normal visual field OD and a paracentral temporal scotoma OS. Magnetic resonance imaging scan disclosed a sellar mass, expanding mainly into the left suprasellar area. Laboratory findings and pathological studies were consistent with a prolactin-secreting pituitary adenoma. While involvement of the temporal visual field in only one eye (junctional scotoma of Traquair) is found in about 10% of patients with pituitary adenoma, involvement of only the paracentral temporal visual field in one eye is rare (1-2%). Recognition of this rare syndrome is important because careful visual field analysis discloses a vertical step and helps to avoid misdiagnosing optic neuritis.
An investigation was carried out to determine the morphologic characteristics of elastic fibers in the superficial layer of the lamina propria of aged vocal folds (EFAVFs). Excised human adult vocal folds served as the material for this study. Scanning and transmission electron microscopic observations were made. The results can be summarized as follows. First, the EFAVFs were composed of amorphous substances and microfibrils. The amorphous substances increased in amount and the microfibrils became less numerous. Second, the EFAVFs ran in various directions, were branched, and formed a complicated network. The surface of the fibers was rough, and the fibers appeared to vary in size. Some EFAVFs united to form a sheet with a rough surface. Third, the EFAVFs could not be easily digested by elastase compared with those of younger adults. We conclude that the morphologic and metabolic changes of elastic fibers in the most important vibrating portion (superficial layer of the lamina propria) of the aged vocal folds contribute partially to aging of the voice.
An investigation was carried out to determine the fine three-dimensional structure of pericytes in excised human vocal fold mucosa, by means of scanning and transmission electron microscopic observation. The results are summarized as follows. 1) There were many pericytes around the true capillaries, arterial capillaries, and venous capillaries in the vocal fold mucosa. 2) Newborns had pericytes around the capillaries in the vocal fold mucosa. 3) The pericytes had bulged fusiform or polygonal cell bodies and branching processes. The branching processes consisted of long and relatively thick longitudinal ones and short circumferential ones. 4) The cell body and processes of the pericytes encircled the capillaries, and the tips of the processes formed intercellular tight junctions with endothelial cells and made a firm connection with them. 5) The pericytes had many cytoplasmic filaments. 6) The pericytes in the vocal fold mucosa appeared to support and protect capillary walls in the vibrating tissue.
Nearly 51,000 Cubans were afflicted during an outbreak of an optic neuropathy (ON) and peripheral neuropathy (PN) between 1991 and 1993. We re-examined 14 of 20 affected individuals 16 months after an initial evaluation. The optic features were painless symmetric vision loss with poor visual acuity, color vision loss, central or cecocentral scotoma, optic disc pallor, and nerve fiber layer drop-out. The neurologic symptoms included stocking-glove sensory changes, hearing loss, leg cramps, sensory ataxia, hyperactive or absent reflexes, and complaints of memory loss. Two of 11 ON probands tested harbored Leber's hereditary optic neuropathy (LHON)-associated mitochondrial DNA mutations. All patients had received multivitamin therapy. We performed comparisons using the paired two-tailed t test. On re-examination, 12 of 14 patients demonstrated improvement. One patient remained unchanged. One woman with the nt-3460 mtDNA mutation showed a decline in vision. In patients not harboring mtDNA mutations, overall visual acuity, color vision, and peripheral neuropathy manifestations improved significantly (p < 0.001 for each manifestation). Most of the patients with Cuban ON and PN improved on multivitamin therapy. The significance of the mtDNA mutations is unclear. In the 2 LHON patients, manifestation of the disease may have been precipitated by nutritional deficiency. Patients with poor recovery or further deterioration should be evaluated for other factors, including poor vitamin therapy compliance and alternative diagnoses.
Coenzyme Q10 (CoQ10) transfers electrons from complexes I and II of the mitochondrial respiratory chain to complex III. There is one published report of human CoQ10 deficiency describing two sisters with encephalopathy, proximal weakness, myoglobinuria, and lactic acidosis. We report a patient who had delayed motor milestones, proximal weakness, premature exertional fatigue, and episodes of exercise-induced pigmenturia. She also developed partial-complex seizures. Serum creatine kinase was approximately four times the upper limit of normal and venous lactate was mildly elevated. Skeletal muscle biopsy revealed many ragged-red fibers, cytochrome c oxidase-deficient fibers, and excess lipid. In isolated muscle mitochondria, impaired oxygen consumption was corrected by the addition of decylubiquinone. During standardized exercise, ventilatory and circulatory responses were compatible with a defect of oxidation-phosphorylation, which was confirmed by near-infrared spectroscopy analysis. Biochemical analysis of muscle extracts revealed decreased activities of complexes I+II and I+III, while CoQ10 concentration was less than 25% of normal. With a brief course of CoQ10 (150 mg daily), the patient reported subjective improvement. The triad of CNS involvement, recurrent myoglobinuria, and ragged-red fibers should alert clinicians to the possibility of CoQ10 deficiency.
This report concerns the characterization of the alpha-tocopherol transfer protein (alpha-TTP) gene in a Japanese family affected by ataxia with isolated vitamin E deficiency (AVED). The sequence analysis revealed a G-to-A transition at the 3' end of exon 3 in both alleles, which predicts outsplicing of this exon from premessenger RNA and the concomitant frame shift in the ataxic patient. We used reverse transcriptase-polymerase chain reaction to analyze alpha-TTP gene transcripts. All transcripts in peripheral blood lymphocytes of the AVED patient, who was treated with large doses of vitamin E, lacked exon 3. The deduced truncated protein shares only 43% of the normal alpha-TTP. Normal control tissues and cells contained normal transcripts and, unexpectedly, also the same mutant transcripts as those of the patient, although with different transcription levels. Treatment of normal fibroblasts with clinically relevant concentrations of vitamin E increased production of transcripts in a dose-dependent manner. We propose that exon skipping of all transcripts through the complete inactivation of the splice site accounts for the clinical onset of AVED and for the clinical resistance to vitamin E in our patient.
Langerhans cells are important in the human immune system as a part of the dendritic cell system. This study was carried out to demonstrate the presence of Langerhans cells and their distribution in normal human larynx and hypopharynx, by light (S-100 polyclonal antibody) and transmission electron microscopy. The results are summarized as follows: 1) Langerhans cells with cytoplasmic granules (Langerhans granules or Birbeck's granules) were situated in the suprabasal region of the squamous epithelium in the larynx and the hypopharynx. 2) They distributed in the membranous portion of the vocal folds, epiglottis, aryepiglottic folds, arytenoid regions and interarytenoid notch of the larynx. The cells surrounded the vestibule and glottis of the larynx. 3) They distributed in the postcricoid area, piriform sinus and posterior pharyngeal wall of the hypopharynx. The cells were situated above the entrance of esophagus. 4) The cells were suggested to be a factor of immune response at the entrance of trachea and esophagus.
This study was carried out to determine the ultrastructure of the mucous membrane of vocal folds of human newborns. Excised larynges of newborns were observed with a transmission electron microscope. The results obtained are summarized as follows: 1) The epithelium of the edge of the vocal folds consisted of stratified squamous epithelium. It was thin but numerous desmosomes showed firm attachment between cells. 2) The basement membrane zone had the same structure as that of adults. 3) The lamina propria of the vocal fold mucosa was loose in structure and there was no vocal ligament. 4) Fibroblasts were sparse and in the resting phase. 5) Collagenous and elastic fibers were sparse in the lamina propria. Structures of the the collagenous fibers wee mature but those of elastic fibers, were immature morphologically. 6) Ground substance was abundant in the lamina propria. 7) The newborn vocal fold mucosa lacked not only a vocal ligament but also adequate viscoelasticity for vibration.