Biomedical subjects

M Takemitsu

Publications and source records attributed to M Takemitsu.

At least 19 recordsLinked to original sources

PubMed2001

Effect of vitamin K(2) on lumbar vertebral bone: histomorphometric analyses in experimental osteoporotic rats.

The in-vivo effect of vitamin K(2) on bone metabolism was investigated by histochemical and morphometric methods, using an animal model of osteoporosis. Eighteen female Wistar rats were divided into three groups. Rats in group A had sham ovariectomies, group B were ovariectomized, and group C were ovariectomized and received vitamin K(2), at 10 mg/kg per day, injected subcutaneously. The lumbar vertebral bones were evaluated 8 weeks after the operation by a modified tetrachrome method after decalcification. Mineralized bone areas, osteoid, and defectively mineralized bone areas in group B were markedly decreased compared with findings in group A, but these features in group C were not severely decreased. There was no significant difference in total bone areas and total bone volumes among the three groups. Accordingly, it appeared that vitamin K(2) had an effect in reducing mineralized bone loss after the ovariectomy. In conclusion, vitamin K(2) is thought to be beneficial for the properties of bone microarchitecture in the condition of osteoporosis.

Animals↗

PubMed1999

Peripheral mononeuropathy induced by loose ligation of the sciatic nerve in the rat: behavioral, electrophysiological and histopathologic studies.

The relationship between clinical parameters and pathological changes was investigated in an animal model of mononeuropathy, by behavioral, electrophysiological and histopathological methods. Mononeuropathy was induced in rats by loosely tying ligatures around the sciatic nerve. Eighty-four rats were used, and these were divided into fourteen groups to determine chronological changes in the withdrawal reflex latency, nerve conduction velocity and ultrastructure of the nerve from 1 to 84 days after nerve ligation surgery. Pathological changes around the ligated nerves were divisible in three phases: the first week was an inflammatory phase, when axonal degeneration, phagocyte infiltration and interstitial edematous changes were observed. The second and third weeks were a nerve-sprouting phase, when numerous axonal sprouts and remyelination were seen. The fourth to twelfth weeks were a recovery phase in which maturing myelination and interstitial fibrosis were characteristic. In the inflammatory phase, withdrawal reflex latencies were shortened, and sensory nerve conduction velocities (SCV) and motor nerve conduction velocities (MCV) gradually decreased. In the nerve-sprouting phase, the latency values remained low, and SCV and MCV were minimal. The parameters examined gradually returned to control levels during the recovery phase. In conclusion, these findings increase the knowledge of disease progression in mononeuropathy with hyperalgesia in human and animal models.

Animals↗

PubMed1998

Pathology study of rabbit calf muscles after repeated compression.

: To elucidate the pathogenesis of chronic compartment syndrome, we examined pathological changes in the soleus (red) and extensor digitorum longus (EDL; white) muscles in Japanese white rabbits after repeated compression with a pneumatic tourniquet. Repeated tourniquet compression via cuff inflation was carried out on the rabbits, calves daily, for 2 h, then stopped for 30 min, and then applied for another 2 h. The contralateral hindlimb, which was not compressed, served as a control. Animals were allocated to 15 groups, with pressures of 40, 80, and 120 mmHg for periods of 1 day, 3 days, 1 week, 2 weeks, and 4 weeks. Skeletal muscle specimens in each group were studied by histopathological and histochemical (ATPase) methods. After compression for 1 day, regardless of pressure, and compression for 3 days in the 40-mmHg pressure group, edematous changes in regions with mild inflammation and increases in fiber diameter were observed in the muscles. After compression for 3 days in the 80- and 120-mmHg pressure groups, and after 1, 2, or 4 weeks in the 40-mmHg pressure group, a few necrotic fibers and scattered fibers with some mononuclear cell infiltrates indicative of early-stage necrosis were detected. In the groups with 80 or 120 mmHg pressure for 1, 2, or 4 weeks, muscle fibers exhibited marked degenerative changes, which were more pronounced in the 120-mmHg group than in the 80-mmHg group. The pathological changes were more pronounced in the soleus than in the EDL muscles, indicating that these two muscles differed in sensitivity to repeated compression. Additionally, average muscle wet weight and average fiber diameter for both types of muscle were increased in the 1-day and 3-day compression groups and decreased in the 1-week, 2-week, and 4-week compression groups. These findings clearly differ from those of previously reported single-compression experiments. Our findings indicate that repeated compression may cause serious muscle degeneration, particularly in red muscles.

Adenosine Triphosphatases↗

PubMed1998

Presence of emerinopathy in cases of rigid spine syndrome.

Rigid spine syndrome (RSS) shows clinical similarities to Emery-Dreifuss muscular dystrophy (EDMD). Differential diagnosis between EDMD and RSS is essential because EDMD is often associated with life-threatening cardiomyopathy that can be cured by an implantation of a cardiac pacemaker. To determine if any of the patients with RSS had mutations of the emerin gene (responsible gene for X-linked EDMD or emerinopathy), we screened the patients for mutations. We found seven patients with a clinical picture consistent with RSS in the 6500 diagnostic muscle biopsies in our National Center over the last 19 years. We identified a novel mutation in the gene (1-bp frame-shift deletion in the exon 1) in one of the seven patients with RSS. This mutation created a premature termination at codon 12 and was expected to produce a severely truncated emerin. Emerin was not detected in the skeletal muscle. The unaffected mother of the patient was a heterozygous carrier for the mutation. The remaining six patients with RSS had no mutation in the gene and showed normal expression of emerin in the skeletal muscle. Our results emphasize the presence of clinical overlap between possible RSS and EDMD, and reinforce the necessity of molecular genetic diagnosis of emerin to exclude emerinopathy in a patient population that has a clinical diagnosis of RSS.

Adolescent↗

PubMed1995

Dystrophin-positive muscle fibers following C2 myoblast transplantation into mdx nude mice.

To determine when and how the dystrophin-positive muscle fibers are formed after myoblast transplantation into dystrophin-negative muscles, the tibialis anterior (TA) muscle from mdx nude mouse was chronologically examined after C2 myoblast transplantation by immunohistochemical and glucose 6-phosphate isomerase (GPI) isoenzyme analyses. The host TA muscle transplanted with C2 myoblasts became necrotic with accumulation of basic fibroblast growth factor in the necrotic areas. This may stimulate concomitant proliferation of the host satellite cells and C2 myoblasts. Small dystrophin-positive muscle fibers appeared in the necrotic areas 3 days after transplantation. This TA muscle contained two different kinds of homodimer GPI isoenzymes but did not contain the heterodimer, suggesting rare fusion of host and donor cells. The dystrophin-positive muscle fibers in the necrotic areas rapidly increased in number and in size by 7 days, but they were smaller than the original host muscle fibers. They had central nuclei, indicating that they were regenerating fibers. The presence of heterodimer GPI isoenzyme in these muscles indicated that the regenerating fibers were mosaic host/donor muscle fibers. The dystrophin-positive muscle fibers are probably formed first by fusion of donor cells with each other and then later by the fusion of host satellite and donor cells.

Animals↗

PubMed1994

Selective defect in dystrophin-associated glycoproteins 50DAG (A2) and 35DAG (A4) in the dystrophic hamster: an animal model for severe childhood autosomal recessive muscular dystrophy (SCARMD).

To determine if dystrophin and dystrophin-associated glycoproteins (DAGs) are involved in muscle fiber necrosis in the dystrophic hamster, we examined NSJ-my/my (homozygous dystrophic) hamsters introduced from the BIO14.6 strain, by immunohistochemical and immunoblotting methods. Antibodies against dystrophin, utrophin and DAGs including 50DAG (A2), 43DAG (A3a) and 35DAG (A4) were employed for the examination. Dystrophin was stained strongly and utrophin stained very faintly along the sarcolemma of the dystrophic hamster, similar to the control. On the other hand, in the dystrophic hamster 50DAG (A2) and 35DAG (A4) were selectively defective, and 43DAG (A3a) was also decreased, although to a lesser degree. Since these results were almost identical to those seen in severe childhood autosomal recessive muscular dystrophy (SCARMD), the dystrophic hamster appears to be an animal model of SCARMD in which defects in DAGs may result in muscle fiber necrosis despite normal dystrophin expression.

Animals↗

PubMed1994

Human mitochondria and mitochondrial genome function as a single dynamic cellular unit.

rho 0 HeLa cells entirely lacking mitochondrial DNA (mtDNA) and mitochondrial transfection techniques were used to examine intermitochondrial interactions between mitochondria with and without mtDNA, and also between those with wild-type (wt) and mutant-type mtDNA in living human cells. First, unambiguous evidence was obtained that the DNA-binding dyes ethidium bromide (EtBr) and 4',6-diamidino-2-phenylindole (DAPI) exclusively stained mitochondria containing mtDNA in living human cells. Then, using EtBr or DAPI fluorescence as a probe, mtDNA was shown to spread rapidly to all rho 0 HeLa mitochondria when EtBr- or DAPI-stained HeLa mitochondria were introduced into rho 0 HeLa cells. Moreover, coexisting wt-mtDNA and mutant mtDNA with a large deletion (delta-mtDNA) were shown to mix homogeneously throughout mitochondria, not to remain segregated by use of electron microscopic analysis of cytochrome c oxidase activities of individual mitochondria as a probe to identify mitochondria with predominantly wt- or delta-mtDNA in single cells. This rapid diffusion of mtDNA and the resultant homogeneous distribution of the heteroplasmic wt- and delta-mtDNA molecules throughout mitochondria in a cell suggest that the mitochondria in living human cells have lost their individuality. Thus, the actual number of mitochondria per cell is not of crucial importance, and mitochondria in a cell should be considered as a virtually single dynamic unit.

DNA, Mitochondrial↗

PubMed1994

[Significance of rimmed vacuoles in neuromuscular disorders--a comparative immunohistochemical study of inclusion body myositis and distal myopathy with rimmed vacuole formation].

Of 3,403 muscle biopsies from patients with a variety of neuromuscular disorders, 87 (2.6%) had at least three muscle fibers with rimmed vacuoles in a single low power field (magnificantion x 20). The rimmed vacuole formation may be a crucial pathologic findings to understand the pathogenesis of inclusion body myositis (IBM), distal myopathy with rimmed vacuole formation (DMRV), Marinesco-Sjögren syndrome and oculopharyngodistal myopathy, because the muscle fibers in these biopsies showed no striking necrotic and denervating changes. Since Congo red positive material and ubiquitin- and beta-amyloid protein-positive deposits were found in muscle fibers with rimmed vacuoles in DMRV and various neuromuscular disorders besides IBM, these findings may have no disease-specific significance and may be not helpful in differentiating DMRV from IBM.

Diagnosis, Differential↗

PubMed1994

[Dystrophin-related protein in diaphragm, limb and myoblast transferred muscles of mdx mouse].

Expression of the dystrophin-related protein (DRP or Utrophin) was examined with Western blot and immunohistochemical methods in diaphragm, limb and also in myoblast transferred muscles of the mdx mouse. Although we have hypothesized that progressive fibrosis in the diaphragm of the mdx mouse has been due to a smaller amount of DRP expression compared with limb muscles, we could not find any difference in the amount of DRP or in the DRP localization pattern between the two muscle sites. In limb muscles treated with myoblast transfer, dystrophin-positive muscle fibers had no DRP on their surface membrane, although dystrophin-negative muscle fibers were DRP-positive. These findings suggest that excessive expression of DRP is suppressed in the normalized muscle fiber with dystrophin. It also appears that the histological differences seen in the different muscles of the mdx mouse are not due to the amount of DRP present.

Animals↗

PubMed1993

Immunoblot analysis of dystrophin-related protein (DRP).

Polyclonal antibodies against the carboxy-terminal portion of dystrophin-related protein (DRP), the putative autosomal gene product which shares sequence homology with dystrophin, show the clear expression of DRP in mouse fetal muscle and in cultured human muscle cells, but not in mature mouse or human muscle. DRP has the same molecular mass as X-linked dystrophin and is recovered from the membrane fraction, but is associated with membranes more loosely than dystrophin.

Amino Acid Sequence↗

PubMed1993

Dystrophin-related protein in skeletal muscles in neuromuscular disorders: immunohistochemical study.

Thirty-four biopsied muscles of Duchenne, Becker and congenital muscular dystrophy, congenital myotonic dystrophy and amyotrophic lateral sclerosis were examined by an immunocytochemical method with an anti-dystrophin-related protein (DRP) antibody. Strongly positive immunoreaction to DRP at the neuromuscular junctions in all biopsied specimens and faint reaction on the surface membrane of atrophic fibers in amyotrophic lateral sclerosis suggest that DRP is an anchor protein of the acetylcholine receptor. Additionally, the surface membrane of muscle fibers of Duchenne muscular dystrophy was positively stained. DRP is, therefore, thought to be expressed to compensate for dystrophin deficiency in these muscle fibers.

Amino Acid Sequence↗

PubMed1993

Monomelic muscle atrophy.

Two patients with slowly progressive muscle atrophy limited to only one leg are reported. They had pes equinovarus deformity and muscle weakness in the affected leg but no symptom in the other limbs. Muscle biopsies from the affected leg showed dystrophic changes consisting of variation in muscle fiber size, endomysial fibrosis, and necrotic and regenerating fibers. Dystrophin was normally expressed at the surface membrane of the muscle fibers. These two patients possibly had a variant of distal muscular dystrophy, though a neural influence could not be completely excluded.

Biopsy↗

PubMed1992

An experimental model of mitochondrial myopathy: germanium-induced myopathy and coenzyme Q10 administration.

In skeletal muscles from rats treated with germanium for 23 weeks, there were numerous ragged-red fibers and cytochrome-c oxidase (COX)-deficient fibers. Biochemically, germanium reduced the enzyme activities in the mitochondrial respiratory chain. Rotenone-sensitive NADH-cytochrome-c reductase as well as COX activities were markedly reduced, while succinate-cytochrome-c reductase was less severely, but significantly, affected. The histopathological findings in these muscles were similar to those seen in patients with mitochondrial encephalomyopathy, suggesting that germanium-induced myopathy may be a useful experimental model. Coenzyme Q10 administration appeared to be ineffective in preventing this experimental myopathy.

Animals↗

PubMed1992

Recovery of the missing tumorigenicity in mitochondrial DNA-less HeLa cells by introduction of mitochondrial DNA from normal human cells.

The role of mitochondrial DNA (mtDNA) in the expression of the transformed phenotype was examined using mtDNA-less HeLa cells. Complete depletion of mtDNA and its products in the mtDNA-less HeLa cell line, EB8, was confirmed by Southern blot analysis and by [35S]methionine labeling of mitochondrially synthesized polypeptides. The tumorigenicity of the EB8 cells was assayed by inoculation of 1 x 10(7) cells subcutaneously into the backs of nude mice. The results showed that the tumorigenicity of HeLa cells was lost in good correspondence with the loss of mtDNA. However, the growth of EB8 cells in culture was very poor compared with that of HeLa cells, indicating that the apparent loss of tumorigenicity in EB8 cells could possibly be due to poor growth of the cells. Introduction of mtDNA from normal human fibroblasts into EB8 cells restored both the missing tumorigenicity and growth of the EB8 cells. These observations could be interpreted to show that mtDNA is required for expression of tumorigenicity, but that mutational changes of the mtDNA are not required for modulation of the phenotype in our experiments.

Animals↗

PubMed1991

Introduction of disease-related mitochondrial DNA deletions into HeLa cells lacking mitochondrial DNA results in mitochondrial dysfunction.

Mutant mitochondrial DNA with large-scale deletions (delta-mtDNA) has been frequently observed in patients with chronic progressive external ophthalmoplegia (CPEO), a subgroup of the mitochondrial encephalomyopathies. To exclude involvement of the nuclear genome in expression of the mitochondrial dysfunction characteristic of CPEO, we introduced the mtDNA of a CPEO patient into clonal mtDNA-less HeLa cells and isolated cybrid clones. Quantitation of delta-mtDNA in the cybrids revealed that delta-mtDNA was selectively propagated with higher levels of delta-mtDNA correlating with slower cellular growth rate. In these cybrid clones, translational complementation of the missing tRNAs occurred only when delta-mtDNA was less than 60% of the total mtDNA, whereas accumulation of delta-mtDNA to greater than 60% resulted in progressive inhibition of overall mitochondrial translation as well as reduction of cytochrome c oxidase activity throughout the organelle population. Because these cybrids shared the same nuclear background as HeLa cells, these results suggest that large-scale deletion mutations of mtDNA alone are sufficient for the mitochondrial dysfunction characteristic of CPEO.

Adolescent↗

PubMed1991

Dystrophin-related protein in the fetal and denervated skeletal muscles of normal and mdx mice.

The amino acid sequence of the polyclonal antibodies we developed against the carboxyl terminus of the dystrophin-related protein, the putative gene product of B3 cDNA, had no homologous sequence to the dystrophin molecule except for two amino acids located at its ends for immunization. By immunohistochemical examination in C57B1/10ScSn and C57B1/10ScSn-mdx mice we found that the DRP was expressed on the surface membrane of fetal muscle fibers, was assembled at the neuromuscular junctions of the mature muscle fibers, and reappeared on the surface membrane of muscle fibers after denervation. Its localization was similar to that of the acetylcholine receptor, suggesting that DRP is one of the cytoskeletons which organize and stabilize the cytoplasmic domain of the acetylcholine receptor.

Aging↗

PubMed1990

[Muscle regeneration in mdx mouse, and a trial of normal myoblast transfer into regenerating dystrophic muscle].

The most ideal therapeutic trial on Duchenne muscular dystrophy (DMD) is a transfer of normal myoblasts into dystrophic muscle which has been attempted on animal models in several institutes. In the process of muscle regeneration, the transferred normal myoblasts are expected to incorporate into the regenerating fibers in host dystrophic mouse. To know the capacity of muscle regeneration in dystrophic muscle, we compared the regenerating process of the normal muscle with that of the dystrophic muscle after myonecrosis induced by 0.25% bupivacaine hydrochloride (BPVC) chronologically. In the present study, C57BL/10ScSn-mdx (mdx) mouse was used as an animal model of DMD and C57BL/10ScSn (B10) mouse as a control. There was no definite difference in the behavior of muscle fiber regeneration between normal and dystrophic muscles. The dystrophic muscle regenerated rapidly at the similar tempo to the normal as to their size and fiber type differentiation. The variation in fiber size diameter of dystrophic muscle, however, was more obvious than that of normal. To promote successful myoblast transfer from B10 mouse into dystrophic mdx mouse at higher ratio, cultured normal myoblasts were transferred into the regenerating dystrophic muscle on the first and the second day after myonecrosis induced by BPVC. Two weeks after the myoblast injection, the muscles were examined with immunohistochemical stain using anti dystrophin antibody. Although dystrophin-positive fibers appeared in dystrophic muscle, the positive fibers were unexpectedly small in number (3.86 +/- 1.50%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1983

Conformational change of mastoparan from wasp venom on binding with phospholipid membrane.

The conformational change upon binding with phospholipid membrane has been studied of mastoparan from wasp venom, a tetradecapeptide causing the degranulation of mast cells. The 270-MHz 1H-NMR spectra and CD spectra indicate that the mastoparan molecule takes the alpha-helical conformation in methanol solution, but a much less ordered form in aqueous solution. On binding with phospholipid membrane, the alpha-helical conformation is formed even in aqueous medium. Such a conformational change is primarily due to the interaction between the aliphatic side chains of mastoparan and the hydrophobic interior of phospholipid membrane, in contrast to the case of melittin from bee venom.

Bee Venoms↗