Biomedical subjects
Publications and source records attributed to M Inagaki.
A 100kD microtubule-bundling protein dynamin was phosphorylated in vitro by cdc2 kinase to approximately 1 mol of phosphate/mol of dynamin at a serine residue. These phosphorylations of dynamin greatly reduced its binding ability to microtubules.
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Cervical magnetic stimulation was used to establish the normal values of the peripheral motor nerve conduction of the upper extremity muscle in normal children and adolescents. Seven patients with peripheral neuropathy were also examined to evaluate a lesion in the proximal site of the peripheral motor nerve. In normal subjects, onset latencies and negative wave durations tended to increase with age. The developmental profile of the latency, corrected for arm length, revealed a significant decline until the age of about 5 years. In 4 cases with polyradiculoneuropathy, motor evoked potentials following cervical magnetic stimulation showed increased latencies, prolonged durations and polyphasic shapes. The time differences between latencies by magnetic stimulation and peripheral motor conduction times by F technique were significantly prolonged. Motor evoked potentials obtained in 3 cases of axonal degeneration, on the other hand, showed slightly increased latencies and normal durations. The time differences between latencies and peripheral motor conduction times were within the normal range. Thus, we consider that cervical magnetic stimulation is a useful method for study of peripheral motor conduction in children and adolescents, and in particular to evaluate the proximal lesion of the nerve in patients with polyradiculoneuropathy.
In children with moyamoya disease, the time courses of hemoglobin concentrations before and after hyperventilation were examined using near-infrared spectrophotometry (NIRS) to determine brain tissue oxygenation. Five patients were studied: 1 was studied both before and after surgery and 4 were studied only after surgery. Nine hemispheres of these 5 patients were examined. The oxygenated hemoglobin concentration increased immediately after beginning hyperventilation. This parameter later decreased sharply to below the prehyperventilation level and remained at the reduced level for a prolonged period. These changes in oxygenated hemoglobin concentration were similar to those previously reported in arterial blood oxygen and CO2 tension. The magnitude of variance in oxygenated hemoglobin concentration (C-HV) was significantly greater in moyamoya disease patients than in healthy controls (P < .003, Wilcoxon test). The changes of NIRS after operation were markedly more sensitive than those of electroencephalography or single-photon emission computed tomography. NIRS could be applied to cerebral oxygenation as well as cerebral hemodynamics, which may be used to better define the time sequence and pathologic processes of various childhood encephalopathies.
Reversible protein phosphorylation plays an essential role in controlling cellular functions. Accumulating evidence indicates that the subcellular distribution of protein kinase and phosphatase activities is organized dynamically. The spatiotemporal dynamics of kinase and phosphatase activities appears to account for the elaborate coordination of the cellular functions achieved by protein phosphorylation and dephosphorylation.
Phosphorylation of neurofilament-L protein (NF-L) by the catalytic subunit of cAMP-dependent protein kinase (A-kinase) inhibits the reassembly of NF-L and disassembles filamentous NF-L. The effects of phosphorylation by A-kinase on native neurofilaments (NF) composed of three distinct subunits: NF-L, NF-M, and NF-H, however, have not yet been described. In this paper, we examined the effects of phosphorylation of NF proteins by A-kinase on both native and reassembled filaments containing all three NF subunits. In the native NF, A-kinase phosphorylated each NF subunit with stoichiometries of 4 mol/mol for NF-L, 6 mol/mol for NF-M, and 4 mol/mol for NF-H. The extent of NF-L phosphorylation in the native NF was nearly the same as that of purified NF-L. However, phosphorylation did not cause the native NFs to disassemble into oligomers, as was the case for purified NF-L. Instead, partial fragmentation was detected in sedimentation experiments and by electron microscopic observations. This is probably not due to the presence of the three NF subunits in NF or to differences in phosphorylation sites because reassembled NF containing all three NF subunits were disassembled into oligomeric forms by phosphorylation with A-kinase and the phosphorylation by A-kinase occurred at the head domain of NF-L whether NF were native or reassembled. Disassembling intermediates of reassembled NF containing all three NF subunits were somewhat different from disassembling intermediates of NF-L. Thinning and loosening of filaments was frequently observed preceding complete disassembly. From the fact that the thinning was also observed in the native filaments phosphorylated by A-kinase, it is reasonable to propose the native NF is fragmented through a process of thinning that is stimulated by phosphorylation in the head domain of the NF subunits.
We identified the phosphorylation sites of glial fibrillary acidic protein (GFAP) for cdc2 kinase and Ca(2+)-calmodulin (CaM)-dependent protein kinase II. GFAP was phosphorylated to approximately 0.2 mol of phosphate/mol of GFAP by cdc2 kinase, and this phosphorylation did not induce disassembly of the filament structure. On the other hand, GFAP was phosphorylated to approximately 1.9 mol of phosphate/mol of GFAP by Ca(2+)-CaM-dependent protein kinase II, and this phosphorylation did induce disassembly of the filament. Sequential analysis of the purified phosphopeptides revealed that only Ser8 on GFAP was phosphorylated by cdc2 kinase, whereas Ser13, Ser17, Ser34, and Ser389 on GFAP were phosphorylated by Ca(2+)-CaM-dependent protein kinase II.
We present here an early-onset case of multiple sclerosis (MS) with thalamic lesions. The patient first experienced an episode of ataxic gait at 2 years 3 months of age, with spontaneous remission within 1 month. At 5 years 4 months, she was admitted because of cerebellar ataxia, oculomotor restriction and feeding difficulty. Magnetic resonance imaging (MRI) showed multiple well-defined lesions in the white matter of the cerebellum, mid-brain, periventricle and right frontal lobe. Cerebrospinal fluid (CSF) showed a mild elevation of both immunoglobulin G (IgG) and myelin basic protein (MBP). Serum anti-myelin antibody was also positive, although leukocytosis and elevation of C-reactive protein were not found. Methylprednisolone pulse therapy relieved symptoms within 2 weeks and the abnormal MRI and CSF findings gradually improved. At 6 years 6 months of age, she incurred a third episode of cerebellar ataxia and disturbance of consciousness. Magnetic resonance imaging revealed recurrence and extension of the previous lesions as well as new lesions in the thalamus and internal capsule. CSF IgG and MBP level showed a higher elevation than in the second episode. The combination of the cerebellar, brain-stem, cerebral and thalamic lesions with remission and exacerbation, supported by MRI and CSF findings, allowed the diagnosis of clinically definite MS to be made. This is one of the youngest cases of MS yet described, with the first attack occurring at 27 months of age. In addition, this case is unique for the involvement of the gray matter in the thalamus.
Glial fibrillary acidic protein (GFAP) is an intermediate filament (IF) protein of astroglia, and belongs to the type III subclass of IF proteins. IF proteins are composed of an amino-terminal HEAD domain, a central ROD domain and a carboxyterminal TAIL domain. GFAP, with a molecular mass of approximately 50 KDa, has the smallest HEAD domain among type III IF proteins. Despite its insolubility, GFAP is in dynamic equilibrium between assembled filaments and unassembled subunits, as demonstrated using fluorescently labeled GFAP molecules. Like other IF proteins, assembly of GFAP is regulated by phosphorylation-dephosphorylation of the HEAD domain by altering its charge. This regulation of GFAP assembly contributes to extensive remodeling of glial frameworks in mitosis. Another type III IF protein, vimentin, colocalizes with GFAP in immature, reactive or radial glia, thereby indicating that vimentin has an important role in the build up of the glial architecture.
Expression of vimentin in gastric cancer was immunohistologically examined in 85 surgically resected specimens and evaluated in terms of various clinicopathological features. Vimentin expression was more pronounced in gastric cancers of more advanced type and in those exhibiting a higher degree of infiltrative growth, lymph node involvement and vascular invasion. These results indicate that vimentin expression by gastric cancer might be related to the invasion and metastatic process of cancer cells and could be useful as a prognostic indicator for patients with gastric cancer.
Human hepatoma cell lines (Hep 3B-TS, PLC/PRF/5, and Hep G2), sensitive to growth inhibition by transforming growth factor beta 1 (TGF-beta 1), express TGF-beta receptors type I, type II, and type III. We report that TGF-beta 1 protein selectively increased steady-state levels of the mRNA for the serine/threonine kinase receptor 1 (SKR1), a member of the TGF-beta superfamily receptor genes in these cells, whereas TGF-beta 1 had little effect on expression of the TGF-beta receptor type II gene. This increase of SKR1 mRNA in Hep 3B-TS cells could be detected by Northern blot analysis within 3 h of addition of TGF-beta 1 to the cells, and enhanced message levels peaked at 12 h as long as TGF-beta 1 was present in the culture medium. Hep 3B-TR cells which were resistant to TGF-beta 1 due to lack of both TGF-beta receptors type I and type II, expressed SKR1 mRNA, but it was not induced by TGF-beta 1 protein. The increased expression of SKR1 mRNA in the cells was actinomycin D-sensitive and was not dependent on new protein synthesis. The results indicate that TGF-beta 1 selectively induces SKR1 message at a transcriptional level by a positive regulator.
Although some intracellularly distributed glycosphingolipids are reported to be associated with vimentin intermediate filaments or colchicine sensitive cytoskeleton, no direct evidence for such an association has yet been shown. In this report we demonstrated that the intracellularly distributed ganglioside GM2 directly binds to isolated vimentin intermediate filaments in normal and Tay-Sachs disease human fibroblasts. Indirect immunofluorescence microscopy using a GM2-specific monoclonal antibody demonstrated filamentously distributed GM2 in the cytoplasm. A double staining of Tay-Sachs fibroblasts with anti-GM2 and anti-vimentin monoclonal antibodies strongly suggested that the GM2 positive filaments are vimentin intermediate filaments. We then isolated vimentin, in the presence of a detergent and urea, from the normal human skin fibroblasts and murine mastocytoma cells. In a solid phase enzyme-linked immunosorbent assay, the isolated vimentin dose-dependently reacted with both anti-vimentin and anti-GM2 monoclonal antibodies but not with anti-GM3 or anti-GM1 monoclonal antibody. The molar ratio of GM2 to vimentin was approximately 20:1. The lipid fraction extracted from the purified vimentin preparation was immunostained with anti-GM2 on a thin-layer chromatography plate. Furthermore, only one band was detected at the molecular weight of 57 kDa, after electroblotting and simultaneous immunostaining with anti-GM2 and anti-vimentin monoclonal antibodies. These results clearly indicated that ganglioside GM2 directly binds to vimentin.
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Mismatch negativity (MMN) of the event related potential (ERP) is generated when patients can discriminate two different kinds of stimuli even if he or she is not conscious of their differences. The authors examined auditory ERPs of passive paradigm in 16 patients with severe multiple handicaps. All patients showed no or scarce clinical response to human voices or environmental sounds. This study investigated whether they showed MMN, since it is hard to evaluate their auditory perception clinically. Auditory stimuli were the tone bursts of 700 and 1,000 Hz in frequency offered at a 4:1 occurrence. Nine of 16 patients showed a definite N2 wave followed by an N 1 wave. The latency of the N 2 wave ranged from 150 to 596 milliseconds after the onset of the target stimuli. This N 2 was considered compatible with mismatch negativity (MMN) in healthy patients. These results suggest that the patients could discriminate subtle difference in two kinds of tones, although their responses to auditory stimuli were very poor.
A 62-year-old man who had undergone left lingual segmentectomy for pulmonary tuberculosis developed left chronic localized pleural empyema with multiple bronchial fistulae in the region of surgical gauze left in the thoracic cavity. We surgically removed the gauze and fenestrated the empyema. After disinfection of the region of suppuration, small fistulae which were less than 2 mm in diameter were closed by fibrin-glue-packing and consolidation of the orifices using 40% silver nitrate solution. Two and one-half months later a second operation was performed. Residual large fistulae were closed by fibrin-glue-packing and suturing of their orifices, and the empyema space was then obliterated by muscle flap plombage. The patient's postoperative course was good and the empyema was completely cured with this treatment.
OBJECTIVES: The purpose of this study was to review our experience with Epstein-Barr virus (EBV) hepatitis after liver transplantation. METHODS: During a 68-month period, we performed 668 liver transplants and 585 patients. We identified 11 patients (2 percent), including 5 adults and 6 children with EBV hepatitis after liver transplantation. The diagnosis of EBV hepatitis was established by evaluating allograft biopsies. The histology was confirmed by the use of polymerase chain reaction technology. RESULTS: The average time of diagnosis after liver transplantation was 45 days. Eight of eleven cases occurred within the first six months after transplantation. After the diagnosis of EBV hepatitis, treatment consisted of a decrease in immunosuppression plus antiviral therapy and intravenous immunoglobulin. The one-year actuarial survival for patients with EBV hepatitis, was 73 percent (8 of 11). Two patients died of progressive multi-organ EBV involvement. To determine the risk of developing EBV hepatitis, we reviewed our experience with the administration of antilymphocyte preparations in 585 patients. The patients found to have a significantly greater risk of developing EBV hepatitis included those receiving more than one course of antilymphocyte therapy or greater than a total dose of 70 milligrams of OKT3 in a single course. CONCLUSIONS: EBV hepatitis after liver transplantation is an infrequent event, which may be treated successfully. The occurrence of EBV hepatitis appears closely linked to the use of antilymphocyte preparations.
Liver metastasis located at the confluence of the major hepatic veins developed after an operation for sigmoid colon carcinoma in a 63-year-old patient. Curative resection of the tumor was performed by in situ hypothermic perfusion of the liver and extracorporeal circulation. Intra-abdominal bleeding occurred on the first postoperative day, and ligation of the right inferior phrenic artery was performed via an emergency laparotomy. Only mild elevation of ALT and recovery of the arterial ketone body ratio to the "safety zone" was noted on the second postoperative day. Hepatic function gradually deteriorated after the 4th postoperative day with no distinct cause. Diffuse fatty liver was suspected as a cause of liver failure. The patient died on the 31st postoperative day. The problems encountered in this case are discussed in this paper.
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