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Biomedical subjects

H Fujimura

Publications and source records attributed to H Fujimura.

At least 73 records · Page 4Linked to original sources
PubMed1996

Cation binding at the node of Ranvier in biopsied peripheral nerves of patients with Charcot-Marie-Tooth disease type 1A and hereditary neuropathy with liability to pressure palsies.

The node of Ranvier in myelinated fibers is known to have an affinity to bind cations. Demyelination and remyelination due to abnormal expression of a myelin protein may affect cation binding or vice versa under pathological conditions. To study the cation binding at the node of Ranvier in inherited demyelinating neuropathies associated with over- and under-expression of the peripheral myelin protein 22 (PMP-22), the reaction with ferric ion and ferrocyanide was used to visualize the cation binding sites in biopsied nerves of four patients with Charcot-Marie-Tooth disease type 1A (CMT1A) and two patients with hereditary neuropathy with liability to pressure palsies (HNPP), and the results were compared with those of four patients having acquired neuropathies with normal PMP-22 expression. In CMT1A, nodal widening or paranodal demyelination was associated with dense precipitates focally on both sides of the widened node. Although fainter precipitates were present at the node between remyelinated internodes, the percentage of nodes exhibiting the reaction product between normal and remyelinated internodes was not statistically different from that between normal internodes in CMT1A. In acquired neuropathies, on the other hand, the difference was significant between the two (P < 0.05), with reduction between normal and remyelinated internodes. At the nodes neighboring demylinated internodes, the percentage of nodes exhibiting the reaction product was reduced significantly in both CMT1A and acquired neuropathies, but to a lesser degree in CMT1A. Precipitates were clearly seen at the nodes neighboring a tomaculum in HNPP. The results suggest that preserved cation binding at the node may allow nerves to keep the electrical excitability in CMT1A and HNPP where myelin remodeling takes place at high frequency.

Adolescent↗
PubMed1996

Alzheimer-type pathology in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS).

A 53-year-old Japanese woman with a point mutation in mitochondrial DNA (tRNALeu(UUR), nt3243) consistent with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and Alzheimer-type brain pathology is reported. This woman had suffered myopathy and psychosis without any clinical evidence of, stroke-like episodes during the last 10 years of her life, and had died after an accident. At autopsy 30 h post mortem, a part of the brain was snap frozen for biochemical and histochemical studies, and the remaining part was processed for a routine examination and electron microscopy. In the brain there were no ischemic lesions. Instead, primitive/diffuse senile plaques were found throughout the brain, predominantly in the frontal and temporal lobes, while Alzheimer neurofibrillary tangles were found only in the parahippocampal gyrus. These plaques were positive for beta-protein and mostly negative for tau protein, ubiquitin, neurofilaments, alpha-choline acetyltransferase, and acetylcholinesterase. Mutations in codon 331 of the ND2 gene as well as codons 693, 713 and 717 of the beta-amyloid precursor protein gene, known to be responsible for some cases of familial Alzheimer disease, were not found. Furthermore, coincidental Down syndrome was ruled out by chromosome analysis. The results suggest a possible correlation between this mitochondrial DNA abnormality and Alzheimer-type pathology.

Alzheimer Disease↗
PubMed1996

Accumulation of peripheral myelin protein 22 in onion bulbs and Schwann cells of biopsied nerves from patients with Charcot-Marie-Tooth disease type 1A.

Peripheral myelin protein 22 (PMP-22) is a glycoprotein expressed in the myelin sheath of myelinated Schwann cells. Duplication of the PMP-22 gene and its gene dosage effect have been postulated to be involved in the pathogenesis in the majority of individuals with Charcot-Marie-Tooth disease type 1A (CMT1A). Northern blot analysis has demonstrated that the mean relative ratio of PMP-22 mRNA/beta-actin mRNA in biopsied nerves of patients with CMT1A is significantly higher than that in disease controls. To investigate whether the elevated expression of PMP-22 mRNA is reflected in the amount and the localization of PMP-22, we analyzed PMP-22, myelin basic protein (MBP), protein zero (P0), and S-100 immunoreactivities in biopsied nerves from six patients with CMT1A, five patients with other types of CMT, five patients with acquired demyelinating neuropathies, and two normal subjects. In all patients with CMT other than CMT1A and acquired demyelinating neuropathy, as well as in normal subjects, the myelin sheath was immunoreactive for PMP-22, MBP, and P0, while the Schwann cell cytoplasm was immunoreactive only for S-100. In five out of six patients with CMT1A, however, the PMP-22 immunoreactivity was present not only on the myelin sheath but also in the Schwann cell cytoplasm and onion bulbs (OBs). Although OBs are nonspecific and also seen in other inherited or acquired demyelinating neuropathies, the PMP-22-positive OBs were seen exclusively in CMT1A. The finding suggested that the expression of PMP-22 was abnormal for its localization and probably for the amount in patients with CMT1A carrying duplication of the PMP-22 gene.

Adolescent↗
PubMed1996

Pentoxifylline delays the onset of experimental allergic encephalomyelitis in mice by modulating cytokine production in peripheral blood mononuclear cells.

The effect of pentoxifylline (PTX) on experimental allergic encephalomyelitis (EAE) in mice, a known animal model of multiple sclerosis (MS), was investigated. PTX was orally administrated at 10, 40 and 100 mg/kg/day, respectively. Although oral PTX at these doses had no significant effect on the incidence and severity of EAE, oral PTX (40 mg/kg/day) alone produced a significant delay in the onset of EAE. Semiquantitative reverse transcriptase-polymerase chain reaction analysis revealed that PTX at this dose reduced the mRNA levels for tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta and IL-6 in peripheral blood mononuclear cells (PBMC) of mice with EAE. A histopathological study showed that PTX treatment delayed infiltration of inflammatory cells in the central nervous system (CNS) of mice with EAE. These results indicated that the tolerable dose of PTX had a suppressive effect on the induction phase of EAE by modulating cytokine production in PBMC but had no effect on the severity of EAE. The findings in the present study with animals suggested that a tolerable dose of PTX might prolong the intervals between relapses in MS, but might not improve the clinical sign and symptoms of MS.

Animals↗
PubMed1996

Unique recognition of activin and inhibin by polyclonal antibodies to inhibin subunits.

Inhibin-A is a glycoprotein composed of an alpha subunit containing a glycosylation site and a beta A subunit, whereas activin-A is a homodimer of two inhibin beta A subunits. We examined the recognition of activin-A and inhibin-A by several antisera to the alpha or beta A subunit, and factors affecting the recognition. A total of six polyclonal antibodies to inhibin subunits, i.e., two antisera to a peptide fragment of the alpha subunit [alpha (1-19) and alpha (1-26)], and four antisera to the beta A subunit [beta A (1-10), beta A (70-79), beta A (87-99), and beta A (94-105)], was generated. On Western blot analysis, the anti-beta A (87-99) and beta A (94-105) sera recognized recombinant human activin-A but not inhibin-A under non-reducing conditions. When inhibin-A was deglycosylated with N-glycosidase-F, inhibin-A could be recognized by the anti-beta A (87-99) and beta A (94-105) sera. In addition, when activin-A bound to a nitrocellulose membrane was pre-incubated with recombinant human follistatin, the recognition of activin-A by the anti- beta A (87-99) and beta A (94-105) sera was decreased. These results suggested that the lower affinity of follistatin to inhibin-A than to activin-A might be likely explained as reflecting a site associated with the glycosylation of inhibin-A. However, the exposure of amino acids 87-105 of the inhibin beta A subunit on the molecular surface through deglycosylation did not increase the affinity of inhibin-A for follistatin but rather resulted in poor binding with follistatin. The present data suggest that (1) amino acids 87-105 of the inhibin/activin beta A subunit are located on the molecular surface, although this region of inhibin-A is concealed by the carbohydrate chain of the alpha subunit, (2) the region responsible for follistatin binding within the activin beta A subunit is spanned by amino acids 87-105, and (3) the mode of binding of inhibin-A to follistatin is quite different from that of activin-A to follistatin, and the former may be influenced by glycosylation.

Activins↗
PubMed1996

Follistatin and activin in bone: expression and localization during endochondral bone development.

The involvement of activin and follistatin, an activin-binding protein, in endochondral bone development was examined by sc implantation of demineralized bone matrix in rats. Immunoreactive follistatin was localized in proliferating chondrocytes and round osteoblasts, whereas it was not detected in hypertrophic chondrocytes and osteoblasts surrounding bone marrow. Western blot analysis also revealed that immunoreactive follistatin was higher during the initial stages of chondrogenesis (day 5) and osteogenesis (days 11 and 14) and lower during the conversion from cartilage to bone (day 9). These results suggest that follistatin is produced by proliferating cells, and the expression decreases with differentiation of the cells. Implants injected with follistatin on days 9 and 10 contained lower calcium levels on day 14 than those injected with rat albumin. Furthermore, the follistatin-injected implants were still mainly composed of cartilage, suggesting that the disappearance of follistatin is necessary for the conversion of cartilage to bone. In contrast, immunoreactive activin beta A (55-60 kDa) was continuously detected in implants on days 7-14. The content of C propeptide of type II procollagen was increased and cartilageous area was enlarged on day 7 by activin A injections on days 5 and 6, suggesting a chondrogenic effect of activin in the initial stage of cartilage formation. These results indicate that proliferating chondrocytes and round osteoblasts produce follistatin, and that the activity of activin is regulated by changes in the expression of follistatin at the stages of chondrogenesis and transition from cartilage to bone.

Activins↗
PubMed1996

Lysosomal glycolipid storage in the renal tubular epithelium in mastomys (Praomys coucha).

The renal proximal tubular epithelium of MCC strain of mastomys (Praomys coucha) exhibited a number of cytoplasmic vacuoles after conventional paraffin-embedding procedures. These vacuoles were strongly PAS-positive in cryostat sections. Ultra-structurally, they were double membrane-bound structures filled with myelin figures and acid phosphatase-positive electron-dense matrix. Immunofluorescent microscopy revealed that these structures contained GM2 ganglioside. Other tissues or organs were histologically normal. Mating experiments indicated that the ganglioside storage in MCC mastomys is inherited as an autosomal recessive trait.

Animals↗
PubMed1996

Genetic characterization of protein C deficiency in Japanese subjects using a rapid and nonradioactive method for single-stand conformational polymorphism analysis and a model building.

We studied the molecular basis of protein C deficiency in 28 Japanese families including 4 asymptomatic families. Two showed a decreased level of function with a normal antigen concentration consistent with type II protein C deficiency and the remaining 26 showed type I deficiency with decreases in both function and antigen level. All the exons and intron/exon junctions of the protein C gene were studied using a strategy combining polymerase chain reaction (PCR) amplification and rapid nonradioactive single-strand conformational polymorphism (SSCP) analysis. The PCR-amplified fragments with aberrant migration on SSCP analysis were sequenced. We identified 11 missense mutations, 1 nonsense mutation, 2 neutral polymorphisms, 1 frameshift deletion, 1 inframe deletion, and 1 splice site mutation. We also identified two different rare mutations in the 5'-untranslated region in the protein C gene that may be responsible for the phenotype. Of these molecular defects, ten were novel. From the results of genetic analysis of 47 Japanese families with protein C deficiency reported in this and previous studies, Phe139Val and Met364Ile substitutions and a G8857 deletion were only found in Japanese subjects and seem to be a founder effect. In contrast, Arg169Trp and Val297Met substitutions, both occurring at CG dinucleotides, were commonly observed in not only Japanese but also Western populations, indicating that these are hot spots for mutation in the protein C gene. These molecular defects were found in 22 families in total, accounting for 47% of Japanese families with protein C deficiency. The structural models of the second EGF and protease domains of activated wild-type and mutant human protein C suggest a possible substrate binding exosite on two loops; one from amino acid position 349 to 357 and the other from position 385 to 388, both of which are close to each other in the three-dimensional model.

Amino Acid Sequence↗
PubMed1995

A new variant case of muscle phosphofructokinase deficiency, coexisting with gastric ulcer, gouty arthritis, and increased hemolysis.

Muscle phosphofructokinase (PFK) deficiency includes both clinically and genetically heterogeneous conditions. A 22-year-old man with muscle PFK deficiency due to previously unrecognized mutation was admitted because of gastric ulcer. He had noticed mild fatigability on vigorous exercise, but had never experienced painful cramps and myoglobinuria. His history included five time relapses of gastric ulcer and gouty arthritis at ages 19 and 21 years. His laboratory data showing impaired muscle glycolysis, increased hemolysis, and myogenic hyperuricemia had aspects in common with those reported for the classic form of this disease, except that lactate concentrations in his blood increased considerably after exercise. The mutant PFK enzyme of this patient, who was demonstrated to have a missense mutation, could exert some catalytic activity that permitted glycolytic flux in vivo, thus leading to the absence of typical myopathic symptoms. The association of relapsing gastric ulcer with muscle PFK deficiency was detected for the first time. There is a possibility that oxygen radical-induced tissue damage resulting from increased hypoxanthine on exertion plays a role in the pathogenesis of ulceration, since the patient is more tolerant to exercise than reported cases with the classic form of muscle PFK deficiency.

Adult↗
PubMed1995

Mitochondrial abnormalities of muscle tissue in mice with juvenile visceral steatosis associated with systemic carnitine deficiency.

A mouse with juvenile visceral steatosis (the JVS mouse) has been recognized as a novel animal model for systemic carnitine deficiency. We examined cardiac, skeletal and smooth muscle cells in JVS and control mice by light and electron microscopy. Cardiac and skeletal muscle cells of these mice at 4 weeks of age exhibited a ragged-red appearance after trichrome staining. Electron microscopy, demonstrated increased numbers of mitochondria and lipid droplets in the cells. Compression or distortion of the myofibril bundles, primarily due to the increased number of mitochondria, suggests the possible existence of a functional disturbance of the cardiac and skeletal muscle. In the urinary bladder, only one or two large lipid droplets and slightly increased number of mitochondria were recognized in the perinuclear region of the smooth muscle cells. At 8 weeks of age, the mouse enzyme histochemistry specific for mitochondria, such as cytochrome c oxidase and succinic dehydrogenase, and oil red O staining, confirmed further increases in the number of mitochondria and lipid droplets in the heart. However, the accumulation of these organelles in the skeletal and smooth muscle cells was no greater than that noted in JVS mice at 4 weeks of age. In the cardiac muscle cells, autolysosomes or autophagic vacuoles containing electron-dense membranous, lamellar or whorled structures closely associated with mitochondria and pseudoinclusion bodies in the nucleus were recognized, and bundles of myofibrils were buried under numerous mitochondria, suggesting the existence of disturbed contractile function in the heart of JVS mice. These results indicate that this murine strain associated with systemic carnitine deficiency exhibits a generalized mitochondrial abnormality in the muscle system especially in the heart.

Animals↗
PubMed1995

Familial amyloid polyneuropathy associated with transthyretin Gly42 mutation: a quantitative light and electron microscopic study of the peripheral nervous system.

We performed extensive quantitative analyses of the peripheral nervous system (PNS) of two siblings with familial amyloid polyneuropathy (FAP) caused by a transthyretin (TTR) Gly42 mutation. Pronounced amyloid deposition was found in the sympathetic ganglia (SyG), dorsal root ganglia (DRG) and throughout the length of the peripheral nerve fibers with some accumulation in the more proximal portion. There was severe neuronal loss in the SyG and DRG together with nerve fiber depletion in the nerve trunk, while only a small amount of amyloid deposition with mild fiber loss was seen in the spinal roots. Sprouts of regenerating axons were very scanty even in the spinal nerves or roots. A teased fiber study mainly showed demyelinating fibers, but axonal degeneration was also present throughout peripheral nerves. An electron microscopic study showed fine amyloid fibrils in direct contact with the axoplasmic membrane of demyelinated axons and destruction of axons in some areas. Amyloid deposition within the PINS in this type of FAP resembled that in type I FAP (TTR Met30). However, direct axonal damage by amyloid fibrils appeared to be more prominent in our cases than in type I FAP. Lectin histochemistry using Ulex europaeus agglutinin I demonstrated preferential depletion of small neurons in the DRG and their primary afferent fibers in the spinal dorsal horn. Primary axonal degeneration and ganglionopathy due to amyloid deposition appear to be the pathogenetic mechanisms for peripheral neuropathy in this type of FAP.

Adult↗
PubMed1995

Focal cytochrome c oxidase deficiency in the brain and dorsal root ganglia in a case with mitochondrial encephalomyopathy (tRNA(Ile) 4269 mutation): histochemical, immunohistochemical, and ultrastructural study.

This is the first report with histochemical and immunohistochemical techniques of an autopsy case with mitochondrial encephalomyopathy caused by the mitochondrial tRNA(Ile) (nt4269) A to G mutation showing focal cytochrome c oxidase (COX) deficiency of neuronal cells. The 18-year-old male patient had cardiomyopathy, hearing disability, mental retardation, and seizures. Muscle biopsy exhibited many ragged-red fibers and focal COX deficiency. A postmortem histochemical study on frozen sections of the cerebral cortex, cerebellum, brain stem, and dorsal root ganglia revealed a loss of COX activity in some neuronal cells. On immunohistochemical staining, COX was also defective in a mosaic pattern. Focal COX deficiency may cause variable neurological manifestations in mitochondrial encephalomyopathies.

Adolescent↗
PubMed1995

Clinical and magnetic resonance image correlation in idiopathic cerebellar ataxia.

Sixty-one patients who fulfilled the clinical criteria for idiopathic cerebellar ataxia and who had symptoms at least for 3 years were examined clinically and by magnetic resonance imaging (MRI). Based on the clinical signs, they were divided into patients with pure cerebellar signs (Group 1), patients with additional mild rigidity and/or hyperreflexia (Group 2) and patients with additional severe rigidity and hypokinesia (Group 3). Patients in Group 1 had milder disability and better prognosis than patients in Group 2 or Group 3 (ataxic score: 14.9 vs. 28.6 and 36.0; annual progression ratio: 0.26 vs. 0.65 and 0.70, respectively). We measured the area of the cerebellar vermis, ventral pons and dorsal brainstem on midsagittal T1-weighted MR images for all patients and age- and sex-matched controls. The cerebellar vermis as well as the ventral pons of patients were significantly smaller than corresponding structures in controls (p < 0.001). The ventral pons of patients in Group 2 and Group 3 was significantly smaller than that of patients in Group 1 (p < 0.0001, respectively), and the dorsal brainstem of patients in Group 2 and Group 3 was also significantly smaller than that of patients in Group 1 (p < 0.001, respectively). The ventral pons of patients in Group 3 was significantly smaller than that of patients in Group 2 (p < 0.05) as well. There was a significant correlation between the area of the ventral pons and the annual progression ratio (p < 0.001). With MRI, slight but definite hyperintensities were demonstrated in the pontine base and the medulla of 22 patients on proton density images. In the longitudinal study, patients in Group 2 and Group 3 had atrophy of the ventral pons already at an early stage. The ventral pons of patients in Group 3 was smaller at the initial MR examination than that of patients in Group 2. These observations suggest that patients with smaller ventral pons may have rapid progression and poor prognosis. Thus, even a relatively simple quantitation of the area of the ventral pons may be useful to predict the prognosis of patients, in addition to neurologic assessment at intervals.

Adult↗
PubMed1995

Expression of the inducible isoform of nitric oxide synthase in the central nervous system of mice correlates with the severity of actively induced experimental allergic encephalomyelitis.

A cytokine-mediated excessive increase in nitric oxide (NO) by macrophages or glial cells via an inducible isoform of NO synthase (iNOS) has been proposed to play an important role in demyelinating diseases. To further investigate the role of iNOS in demyelination, experimental allergic encephalomyelitis (EAE), a known animal model of multiple sclerosis (MS) in mice, was chosen in this study. A semiquantitative reverse transcriptase-polymerase chain reaction (RT/PCR) analysis revealed an increase in the mRNA levels of iNOS and cytokines known to induce iNOS or inflammatory cytokines (interleukin (IL)-1 alpha, IL-1 beta, IL-2, IL-6, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha and TNF-beta) in the spinal cord corresponding to the severity of the disease without significant change in the mRNA levels of immunoregulatory cytokines (IL-4, IL-10 and transforming growth factor (TGF)-beta) during the course of EAE. An immunohistochemical examination of the spinal cord using an iNOS-specific antibody showed iNOS-positive cells to be mainly inflammatory cells with a higher frequency of iNOS-positive cells at the peak of EAE than in the early phase. These iNOS-positive cells at the peak appeared to be composed of infiltrating macrophages and most of them were located in the necrotic area. These results suggested that cytokine-induced excessive NO via iNOS by macrophages caused tissue damage in the central nervous system in EAE.

Animals↗
PubMed1995

Effects of acetaminophen on the ultrastructure of isolated rat hepatocytes.

The effects of acetaminophen (AA) on the ultrastructure of isolated hepatocytes (IHC) of rat following incubation of IHC suspensions with AA were examined by electron microscopy. The effect of N-acetyl-p-benzoquinone imine (NAPQI), a putative toxic metabolite of AA, were also observed. IHC were prepared from livers obtained from phenobarbital-treated rats by collagenase perfusion method. With 5 and 20 mM AA, surface blebs mainly containing smooth endoplasmic reticulum (ER) occurred in IHC. Dilatation of Golgi apparatus, partial degranulation of rough ER and enlargement of mitochondria were also observed. The altered mitochondria showed a low electron-dense matrix with loss of mitochondrial granules. With 500 microM NAPQI, surface blebs containing various organelles occurred in IHC. Disorderly distributions of cytoplasmic organelles, mild dilatation of rough and smooth ER and cytoplasmic myeloid bodies were observed. The characteristic myeloid bodies were seemingly derived from degranulated rough ER.

Acetaminophen↗
PubMed1995

Eyelid "apraxia" in patients with motor neuron disease.

Three patients with motor neuron disease had eyelid "apraxia" with impaired voluntary but preserved involuntary eyelid movements. Attempts were made to localise the lesions responsible with neuroimaging and neuropathological examination.

Aged↗