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Biomedical subjects

M Fujioka

Publications and source records attributed to M Fujioka.

At least 145 records · Page 8Linked to original sources
PubMed1994

Bilateral organized chronic subdural haematomas: high field magnetic resonance images and histological considerations.

The authors describe a 66-year-old man with progressive gait disturbance caused by bilateral organized chronic subdural haematomas. The characteristics of these lesions on magnetic resonance (MR) images have not yet been clarified. The organized haematoma in our patient exhibited slight hypo-intensity on T 1-weighted MR images and marked hypo-intensity on T 2-weighted MR images obtained at 1.5T. Preoperative MR imaging may give us useful information about surgical strategy in the case of chronic subdural haematoma with an unusual appearance on computed tomographic (CT) scans.

Aged↗
PubMed1994

Guanidinoacetate methyltransferase in the mouse: extensive expression in Sertoli cells of testis and in microvilli of caput epididymis.

Guanidinoacetate methyltransferase (GAMT) catalyzes the last step of the biosynthetic pathway to creatine (Cr), the transfer of a methyl group from S-adenosylmethionine to guanidinoactate. Despite the importance of this methylation reaction in cellular energy metabolism and in methyl group metabolism, a systematic study of the expression and cellular localization of this enzyme is lacking. As a means for determining why the testis and seminal vesicles contain high levels of Cr, we analyzed GAMT protein and mRNA levels in mouse tissues by Western and Northern blot analyses. The results show that GAMT was regulated at tissue-specific levels; the enzyme was most highly expressed in testis, caput epididymis, ovary, and liver. Differences were also noted between sexes; the levels of GAMT mRNA and protein were higher in female liver than in male liver. Furthermore, as the male mouse developed from neonatal stages through sexual maturity, the GAMT protein level increased in testis but decreased in liver. Immunohistochemical labeling showed that GAMT was localized primarily in Sertoli cells of the testis and in microvilli of the epithelial cells lining the caput epididymis. GAMT expression in Sertoli cells was confirmed by biochemical and molecular analyses of purified testicular cells, testes from prepubertal mice of different ages, and germ cell-deficient mutant mouse testes. These results indicate that Cr is synthesized extensively in the epithelia of seminiferous tubules and caput epididymis, suggesting that GAMT or metabolic pathways related to Cr biosynthesis may be important for germ cell development or function.

Animals↗
PubMed1994

Specific changes in human brain following reperfusion after cardiac arrest.

BACKGROUND AND PURPOSE: Very few reports are available on serial changes in human brain after cardiac arrest. The primary objective of this study is to investigate sequential neuroradiological changes in patients remaining in a persistent vegetative state following resuscitation after cardiac arrest. METHODS: We repeatedly studied eight vegetative patients resuscitated from unexpected out-of-hospital cardiac arrest using computed tomographic (CT) scanning and high-field magnetic resonance (MR) imaging at 1.5 T. RESULTS: In seven of the eight patients, CT scans obtained between days 2 and 6 features symmetrical low-density lesions in the bilateral caudate, lenticular, and/or thalamic nuclei. These ischemic lesions were persistently of low density on serial CT scans. In these seven patients, MR images demonstrated what were thought to be hemoglobin degradation products derived from minor hemorrhages localized in the bilateral basal ganglia, thalami, and/or substantia nigra. Diffuse brain edema in the acute stage and diffuse brain atrophy in the chronic stage were consistent neuroradiological findings. No abnormal enhanced lesions were demonstrated by CT scans. CONCLUSIONS: The most characteristic findings on high-field MR images were symmetrical lesions in the bilateral basal ganglia, thalami, and/or substantia nigra with specific changes suggestive of minor hemorrhages that were not evident on CT scans. We speculate that these minor hemorrhages result from diapedesis of red blood cells in these regions during the reperfusion period through the endothelium disrupted by ischemia-reperfusion insult.

Adult↗
PubMed1994

[Permanent pacemaker lead insertion for totally occluded subclavian vein].

We experienced 4 patients with total occlusion of the subclavian vein in whom permanent pacemakers were implanted. Occlusion of the subclavian vein was not clinically apparent in these 4 patients. The pacing lead was inserted through the contralateral subclavian vein in a 65-year-old male. In a 80-year-old male, the pacing lead was inserted trough the internal jugular vein because of occlusion of both subclavian veins. The pacing lead was passed through the occluded portion of the innominate vein in a 84-year-old male. Phlebography-guided venipuncture was not difficult in a 79-year-old female whose mid-portion of the subclavian vein was occluded. All patients have done well since permanent pacemaker implantation. Preoperative phlebography should be performed as it may provide useful information concerning pathological alterations in the venous system that might hinder smooth implantation of the pacemaker. A review of the literature revealed no reports concerning methods in which pacing leads are passed through totally occluded portions of the subclavian vein. We here report 4 patients with total occlusion of the subclavian vein in whom permanent pacemakers were implanted via different venous routes.

Adult↗
PubMed1994

[A case of Hangman's fracture associated with vertebral arteriovenous fistula treated with trapping].

A case of a traumatic vertebral arteriovenous fistula associated with a hangman's fracture is reported. A 45-year-old male fell down about 2 meters and struck his parietooccipital region against the ground. Profuse nasal bleeding developed. He was transferred to a local hospital, where his respiration was ataxic and blood pressure was low. After intubation, he was transferred to our emergency department. Cervical x-p revealed fracture of C1, C2 and subluxation of C2 body. Because of uncontrollable nasal bleeding, the bilateral maxillary arteries were embolized with spongel. At this time, right vertebral angiograms demonstrated a vertebral arteriovenous fistula with an pseudoaneurysm located at C2 level. On the 13th hospital day, direct balloon occlusion of the fistula was attempted; this could not be achieved because the subclavian and vertebral arteries were tortuous and the balloon catheter could not be introduced to the level of the fistula in the vertebral artery. The patient was only observed until follow-up angiogram on the 24th hospital day revealed enlargement of the pseudoaneurysm. We performed trapping of both the proximal and distal ends of the involved vertebral artery; from C5 to C1. Postoperative course was uneventful, hangman's fracture was fixed with a Halo vest. Four months after operation, fistula and pseudoaneurysm were not opacified on angiogram. We believe that transvascular techniques are the treatment of choice for vertebral arteriovenous fistulas. However, as the next best thing, we can use trapping for the patient whose vessels are too tortuous to introduce the balloon catheter to the involved vessel.

Arteriovenous Fistula↗
PubMed1993

Mutation of histidine 373 to leucine in cytochrome P450c17 causes 17 alpha-hydroxylase deficiency.

We identified a new homozygous missense mutation His373-->Leu in the CYP17 gene of two sisters with 17 alpha-hydroxylase deficiency with an elevated plasma aldosterone concentration by sequencing their genomic DNAs amplified by polymerase chain reaction. Using polymerase chain reaction-based site-directed mutagenesis, we prepared a DNA that encoded the Leu373 mutant protein. COS-1 cells transfected with the mutant DNA, despite having an RNA hybridizable to the P450c17 cDNA, did not show 17 alpha-hydroxylase and 17,20-lyase activities. Also, the cells were devoid of 11 beta-hydroxylase and aldosterone synthase activities. To examine the mechanism by which the single amino acid change His373-->Leu eliminates activity, we expressed N-terminally modified P450c17 proteins with and without the Leu373 mutation in Escherichia coli and performed spectral studies. Membrane preparations from E. coli cells expressing the wild-type form of the modified enzyme showed an absorption peak at 449 nm upon addition of carbon monoxide in the reduced state and produced characteristic substrate-induced difference spectra, whereas those from the cells expressing the mutant form did not show these spectral changes. The 17 alpha-hydroxylase and 17,20-lyase activities were observed only in E. coli cells expressing the wild-type enzyme. These results show that the His373-->Leu mutant does not incorporate the heme prosthetic group properly and suggest a critical role of His373 in heme binding.

Adolescent↗
PubMed1993

Structure of the gene encoding rat neutrophil chemo-attractant Gro.

A cloned rat gro gene encoding the neutrophil chemo-attractant Gro was isolated from a lambda Charon4A rat genomic library, and the nucleotide (nt) sequence of a 2500-bp fragment encompassing the coding region and 3'- and 5'-flanking regions was determined. The gene consisted of four exons separated by three introns. The transcription start point was determined by primer-extension analysis and found to be a G located 72 nt upstream from the start codon. The 5'-flanking region of the gene contained a 'TATA'-like structure and an NF-kappa B-binding sequence.

Amino Acid Sequence↗
PubMed1993

Mammalian glycine N-methyltransferases. Comparative kinetic and structural properties of the enzymes from human, rat, rabbit and pig livers.

1. Human liver contains a rather high level of glycine N-methyltransferase. 2. The enzymes from human, rat, rabbit and pig livers are all tetramers and exhibit positive cooperativity toward S-adenosylmethionine and Michaelis-Menten kinetics toward glycine. The [S]0.5 values for S-adenosylmethionine and glycine of the rat enzyme are considerably lower than those of three other enzymes. 3. The subunit of rat glycine N-methyltransferase is shorter by two residues compared with the subunits of human, rabbit and pig glycine N-methyltransferases. Except for this difference, however, all enzymes show a high degree of sequence homology.

Adult↗
PubMed1993

Recombinant expression of rat and human Gro proteins in Escherichia coli.

A full-length rat gro cDNA containing the signal sequence was inserted to a plasmid/phage vector pTD-lacs which had the Escherichia coli alkaline phosphatase leader sequence down-stream of the lac promoter. After removal of the gro signal sequence by site-directed mutagenesis, the vector was introduced to E. coli JM109. The cells grown in the presence of isopropyl beta-D-thiogalactopyranoside were found to contain the recombinant mature rat Gro protein in the periplasmic space. The protein was released from the cells by osmotic shock, and could be purified to homogeneity from the periplasmic fluid by a single-step procedure using reverse phase high performance liquid chromatography. By similar procedures, recombinant human Gro alpha could be obtained. In each case, about 10 mg of purified cytokine were obtained from 1 litre of bacterial culture.

Animals↗
PubMed1993

Meningioangiomatosis not associated with von Recklinghausen's disease--case report.

A 7-year-old girl with meningioangiomatosis not associated with von Recklinghausen's disease is described. The radiological findings were similar to meningioma, but intraoperatively, a thin septum was found between the mass and the dura mater. Microscopically, there was significant proliferation of fibroblastic spindle-shaped cells and collagenous fibers in the subarachnoid space. Proliferated cells had penetrated into the cortical tissue along the irregularly branched blood vessels. Immunohistochemically, these penetrating perivascular cells were negative for glial fibrillary acidic protein and S-100 protein, and positive for vimentin staining. These findings suggest that the histogenesis of the spindle-shaped cells is most probably meningothelial.

Child↗
PubMed1993

[A case report of CMV hepatitis and nephropathy after living related renal transplantation].

Cytomegalovirus (CMV) infection is serious complication after clinical renal transplantation. A case of CMV hepatitis and nephropathy after living related renal transplantation was reported. A 32-year-old women with chronic renal failure due to systemic lupus erythematosis received a renal transplant from her mother. On day 35 after operation, she developed high fever with hepatic and renal damage and was diagnosed as CMV infection from clinical course and virological examination. Although the use of anti-CMV high titer gamma globulin with reduction of immunosuppressant therapy could not cure the infection, the administration of Ganciclovir improved hepatic and renal damage without deterioration of renal graft function.

Adult↗
PubMed1993

[Traumatic primary brain stem injury and ambient cistern hematoma evaluated with magnetic resonance imaging].

Traumatic hemorrhage in the ambient cistern is thought to be an indirect indication of brain stem injury. In many cases such brain stem lesions cannot be clearly demonstrated by conventional CT scans. Magnetic resonance imaging (MRI) provides a more sophisticated display of the brain stem with improved contrast resolution of structures not appreciated on CT. We present four patients with traumatic ambient cistern hematoma on CT. They showed consciousness disturbance at the initial neurological examination and a Glasgow Coma Scale (GCS) of 7-10. All patients had hemothorax or clavicular fracture ipsilateral to the ambient cistern hematoma that suggested a severe mechanical force from the same direction. Axial, coronal and sagittal MRI scans were obtained with a super-conductive 1.5 T unit (Picker) within 6 days after trauma. Two standard pulse sequences were used; (1) Spin-echo (TR/TE = 500/20) or Inversion Recovery (TR/TI/TE = 3300/600/30) to obtain T1-weighted information and (2) Spin-echo (TR/TE = 2000/100) to obtain T2-weighted information. In case 1 (3-year-old girl) the hematoma which was thought to be located in the ambient cistern on CT was found to be present in the subpial region in the tegmentum on MRI. On T2 weighted image, a high signal intensity area was seen in the perifocal area. This area was demonstrated as a low density area on CT. This patient has remained in a persistent vegetative state 6 months after trauma. In case 3 (31-year-old man) CT demonstrated no abnormal findings in the brain stem. MRI demonstrated a high intensity area in the right cerebral peduncle and left tegmentum.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Identification of a tyrosine residue in rat guanidinoacetate methyltransferase that is photolabeled with S-adenosyl-L-methionine.

Exposure of rat guanidinoacetate methyltransferase to ultraviolet light in the presence of S-adenosyl-L-[methyl-3H]methionine ([methyl-3H]AdoMet) results in covalent linking of radioactivity to the enzyme protein. The incorporation of radioactivity shows no lag and is linear with respect to time up to 1 h. The photolabeling is saturable with [methyl-3H]AdoMet, and the binding constant of the enzyme for AdoMet determined in this experiment is similar to that obtained by equilibrium dialysis. Low concentrations of competitive inhibitors S-adenosyl-L-homocysteine and sinefungin effectively prevent the photoinduced labeling by AdoMet. Although guanidinoacetate methyltransferase is irreversibly inactivated upon ultraviolet irradiation in the absence of AdoMet, the enzyme inactivated by 1-h exposure to ultraviolet irradiation has been shown to bind AdoMet with an affinity identical to that of the native enzyme. These results indicate that photolabeling occurs at the active site. Following proteolysis of the [methyl-3H]-AdoMet-labeled enzyme with chymotrypsin, a radioactive peptide is isolated having a sequence Asp-Thr-X-Pro-Leu-Ser-Glu-Glu-Thr-Trp. The peptide corresponds to residues 134-143, with X being modified Tyr-136. The same peptide is photolabeled when [carboxy-14C]AdoMet is used. High-performance liquid chromatography of this peptide after acid hydrolysis and phenyl isothiocyanate derivatization suggests that the entire molecule of AdoMet is attached to Tyr-136.

Amino Acid Sequence↗
PubMed1992

Rat guanidinoacetate methyltransferase: mutation of amino acids within a common sequence motif of mammalian methyltransferase does not affect catalytic activity but alters proteolytic susceptibility.

1. Manual alignment of amino acid sequences of mammalian S-adenosylmethionine-dependent methyltransferases of known sequence revealed the presence of 2 homologous regions. 2. The sequence of the region at the C-terminal side is unique to mammalian methyltransferases, and in guanidinoacetate methyltransferase this sequence occurs at residues 159-165. 3. Mutagenesis of 5 conserved residues in this sequence did not affect the catalytic activity but altered tryptic susceptibility at Arg20.

Amino Acid Sequence↗