Biomedical subjects

T Uozumi

Publications and source records attributed to T Uozumi.

At least 19 recordsLinked to original sources

PubMed1995

Role of cysteine 337 and cysteine 340 in flavoprotein that functions as NADH oxidase from Amphibacillus xylanus studied by site-directed mutagenesis.

A flavoprotein from Amphibacillus xylanus catalyzes the reduction of oxygen to hydrogen peroxide. Each polypeptide chain in the tetrameric enzyme contains 5 cysteine residues. The complete reduction of enzyme by dithionite requires 6 electrons. Such behavior indicates the presence of redox centers in addition to the FAD, and these could be disulfides. In order to assess the catalytic role of disulfide in the enzyme, 2 of the cysteines (Cys-337 and Cys-340), which show a high degree of homology with alkyl hydroperoxide reductase F52a protein and thioredoxin reductase, have been changed to serines by site-directed mutagenesis of the cloned flavoprotein gene (individually and in a double mutant). Titration of the three mutant enzymes, lacking Cys-337, Cys-340, or both cysteines, requires only 2 electron eq to reach the reduced flavin state. These results indicate the absence of a redox-active disulfide and demonstrate the involvement of Cys-337 and Cys-340 in the redox-active disulfide. The catalytic activity of the three enzymes was examined by steady-state analysis. The Km for NADH and oxygen and the kcat value of these mutant enzymes were essentially the same as those of wild type. The NADH oxidase activities were also accelerated markedly in the presence of free FAD, which is the case for wild-type enzyme. The NADH:5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) oxidoreductase activities of all mutant enzymes were less than 3% of the activity of wild-type enzyme. The weak DTNB reductase activities in the mutant enzymes lacking Cys-337 or Cys-340 may occur through direct reduction of the mixed disulfide Cys-337-thiol or Cys-340-thiol and nitrothiobenzoate by FADH2. However, the weak DTNB reductase activity in the mutant enzyme lacking both cysteines indicates that FADH2 can reduce either DTNB or another disulfide directly, albeit inefficiently. These results suggest intramolecular dithiol-disulfide interchange reactions in the flavoprotein.

Amino Acid Sequence↗

PubMed1995

Temperature acclimation induces light meromyosin isoforms with different primary structures in carp fast skeletal muscle.

Carp acclimated to 10 degrees C gave 69k, 66k, and 62kDa light meromyosin (LMM) fragments in SDS-PAGE, while fish acclimated to 30 degrees C gave 74k, 69k, 66k, and 62kDa fragments. The microsequence analysis revealed that the 69k and 66kDa components from the 10 degrees C-acclimated carp contained an N-terminal amino acid sequence different from that of 62kDa. The four fragments from the 30 degrees C-acclimated carp showed the same sequence as that of the 69k and 66kDa components from the 10 degrees C-acclimated carp, except that the 2nd amino acid, Ala, of the 10 degrees C-acclimated LMM was replaced by Thr. DNA fragments encoding an N-terminal region of LMM were amplified by PCR or reverse transcriptase-PCR, demonstrating that the two acclimated groups further contained several amino acids substituted.

Acclimatization↗

PubMed1995

Growth inhibition of intracerebral rat glioma by transfection-induced human interferon-beta.

In our previous study on liposome-mediated transfection of the human interferon-beta (HuIFN-beta) gene into subcutaneously implanted human gliomas in nude mice, we found that HuIFN-beta was produced and secreted by the tumor cells and that the growth of solid tumors was completely inhibited. The present study investigated the growth-inhibitory effect of liposomes containing the HuIFN-beta gene inserted into a vector (pSV2IFN-beta) on T9 rat glioma implanted into the brains of rats. Tumor cells and liposomes containing pSV2IFN-beta or other additives were simultaneously injected into the brains of rats. HuIFN-beta was detected in solid gliomas growing in the brains of rats injected with liposomes and magnetic resonance imaging (MRI) showed that tumor growth was inhibited. In addition, the latent period until the appearance of neurological symptoms was significantly prolonged in rats treated with liposomes containing pSV2IFN-beta. However, the survival time of the treated rats was not significantly increased.

Animals↗

PubMed1995

Demonstration of the venous systems with gadolinium-enhanced three-dimensional phase-contrast MR venography.

The purpose of this study was to evaluate the usefulness and advantages of gadolinium-enhanced three-dimensional phase-contrast MR venography for demonstrating the venous systems. The three-dimensional phase-contrast MR venography was performed with a velocity encoding gradient settings from 5 to 20 cm/s on 22 normal subjects. In 8 of normal subjects, gadolinium-enhanced phase-contrast MR venography was performed. 22 subjects (100%) had detectable flow in the sphenoparietal sinus, transverse sinus, basal vein, and internal cerebral vein. With a VENC setting at 10 cm/s, venous system was visualized selectively and clearly. Detection ratio in inferior petrosal sinus, superior petrosal sinus, and superior ophthalmic vein increased from 0% to 25%, from 28.6% to 62.5%, and from 28.6% to 37.5%, respectively, after administration of gadopentate dimeglumine. In conclusion, gadolinium-enhanced three-dimensional phase-contrast MR venography was useful for demonstrating the venous systems.

Adolescent↗

PubMed1995

MRI of intracranial germ cell tumours.

We reviewed MRI findings in proven intracranial germ cell tumours in 22 cases, 12 of whom received Gd-DTPA. On T1-weighted images, the signal intensity of the tumour parenchyma was moderately low in 19 cases and isointense in 3; on T2-weighted images, it was high in all cases. Regions of different intensity thought to be cysts were found in 17 (77%): 7 of 12 patients with germinoma (58%) and in all other cases. Of the 13 patients with pineal lesions T1-weighted sagittal images showed the aqueduct to be obstructed in 5, stenotic in 7 and normal in 1. Strong contrast enhancement was observed in all 12 cases. Of the 14 patients with suprasellar lesions, 5 were found to have an intrasellar extension, and in 3 of these, the normal pituitary gland, which could be distinguished from the tumour, was displaced anteriorly. Ten patients (45%) had multiple lesions.

Adolescent↗

PubMed1995

Surface anatomy scanning (SAS) in intracranial tumours: comparison with surgical findings.

We evaluated the usefulness of surface anatomy scanning (SAS) in intracranial tumours, comparing it with surgical findings. We examined 31 patients with brain tumours preoperatively. The tumours included 16 meningiomas, 8 gliomas, 4 metastases and 3 others. SAS clearly demonstrated the tumours, allowing them to be distinguished from the structures of the brain surface, including oedema, except in cases of metastasis. SAS clearly demonstrated large cortical veins. SAS is useful for three-dimensional delineation of the brain surface before surgery.

Brain↗

PubMed1995

Spontaneous disappearance of an aneurysmal malformation of the vein of Galen.

We describe spontaneous disappearance of an aneurysmal malformation of the vein of Galen (AMG), an anomaly that occurs most often in children, with a high mortality due to the accompanying severe cardiac failure. Spontaneous thrombosis of an AMG is rare. In this case, the AMG has been closed for about 5 years, without radiological evidence of thrombosis, and no active treatment. Proposed mechanisms of spontaneous thrombosis include slow flow shunts and severe obstruction of the venous outflow. However, in this case, the disappearance of the AMG without evidence of thrombosis indicates a different mechanisms, namely, obstruction of the feeding artery.

Cerebral Angiography↗

PubMed1995

Sympathetic skin responses evoked by magnetic stimulation of the neck.

We studied sympathetic skin responses (SSRs) following magnetic stimulation of the neck in 40 normal subjects and 54 patients with neurological diseases and active sweat gland densities (ASGDs) at the foot induced by pilocarpine in 39 patients. SSRs at the hand following magnetic stimulation showed the lowest coefficients of variability of the latencies and amplitudes in eight consecutive responses compared with SSRs following other types of stimuli (electrical and auditory stimulation, and deep inspiration) in 12 normal subjects. Fourteen of 38 patients with neuropathies (37%) showed the presence of SSRs after magnetic stimulation, but not after median nerve stimulation, although SSRs to magnetic stimulation corresponded with those to nerve stimulation in all patients with multiple sclerosis or multiple system atrophy. These results suggest that the absence of SSRs after nerve stimulation in patients with neuropathies may be due to abnormalities of the peripheral sensory afferent fibers. ASGDs significantly correlated with SSRs at the foot following magnetic stimulation, but not with those following nerve stimulation in patients with neuropathies. Magnetic stimulation of the neck is the highly reproducible method of evoking SSRs because this technique is able to produce strong sensory afferent inputs proximally. Furthermore, SSRs following magnetic stimulation, little influenced by sensory afferent fiber involvement, are very useful for evaluating the postganglionic sympathetic function in patients with neuropathies.

Action Potentials↗

PubMed1995

Clinicopathologic growth factors of acoustic neuromas.

BACKGROUND Understanding the tumor growth rate is very important when considering strategies for the treatment of an acoustic neuroma, although the natural course of acoustic neuromas has not been reviewed in detail. METHODS The clinicopathologic features and the postoperative growth of tumors were evaluated in 32 patients with acoustic neuromas. This study was undertaken to assess the variability of the growth potential of cells within an acoustic tumor and to determine the relationships between the growth rate and the clinicopathologic characteristics of the patients with acoustic neuromas, including age at surgery, gender, tumor location and preoperative size, the duration of the symptoms, the presence of cystic regions, the presence of Antoni type A and B cells, the tumor cell density, tumor vascularity, mitotic rate, the presence of hyaline degeneration and hemosiderin deposition, nucleolar organizer regions (NORs), and the level of proliferating cell nuclear antigen (PCNA). RESULTS The growth patterns of the tumors were divided into three groups according to their growth rate: a regression group, a "no-growth" group (growth rates from 0-0.11 cm/year) and a progression group (growth rates from 0.19-1.72 cm/year). An additional operation was required in all patients whose growth rate was more than 0.38 cm/year. A statistical study on the factors associated with an increased growth rate showed that the three histopathologic factors most significantly associated with a postoperative growth rate were hyaline degeneration (p < 0.05), cell density (p < 0.005), and PCNA labeling index (p < 0.005). CONCLUSIONS These results strongly suggest that acoustic tumors can be subdivided into several groups, based upon different biologic activities and tumor growth rates.

Adult↗

PubMed1995

Steal phenomenon in a traumatic carotid-cavernous fistula.

A patient with head injury presented with computed tomography findings of a diffuse severe infarction of the left cerebral hemisphere in which the cerebral hemodynamics can be evaluated by transcranial Doppler sonography. Serial angiograms revealed a carotid-cavernous fistula, with a complete steal phenomenon. The unusual complication of a traumatic carotidcavernous fistula is discussed.

Arteriovenous Fistula↗

PubMed1995

Effect of antiepileptic drugs on absence-like seizures in the tremor rat.

We examined the effects of conventional antiepileptic drugs (AEDs) on absence-like seizures in homozygous tremor rats (tm/tm) to determine if they corresponded pharmacologically to human absence seizures and absence-like seizures in spontaneously epileptic rats (SER: zi/zi, tm/tm) with both tonic convulsive and absence-like seizures. Cortical and hippocampal EEG activity was recorded with chronically implanted electrodes. The effects of AEDS on seizures of the tremor rat showed profiles similar to those observed in human absence seizures and also in absence-like seizures of SER. The absence-like seizures, associated with paroxysmal bursts of 5-7-Hz spike-wave complexes, were inhibited by trimethadione (TMO 200 mg/kg intraperitoneally, i.p.), ethosuximide (ESM 100 and 200 mg/kg, i.p.), valproate (VPA 100 mg/kg, i.p.), and phenobarbital (PB 10 and 20 mg/kg, i.p.). Phenytoin (PHT 20 mg/kg, i.p.) was ineffective. These results are consistent with the conclusion that the tremor rat is a useful model for evaluating new AEDS for human absence seizures.

Animals↗

PubMed1995

Transcranial magnetic coil stimulation of motor cortex in patients with central pain.

We report two patients with deafferentation pain secondary to central nervous system lesions who were evaluated by noninvasive magnetic coil stimulation of the motor cortex followed by electrical motor cortex stimulation with epidural electrode array implantation. Magnetic coil stimulation was very useful to estimate the effect of electrical stimulation. Our first patient was a 52-year-old man who experienced a left putamenal hemorrhage at the age of 48. Two years later, he had paresthesias and intractable pain in the extremities and face on the right side. Pain was resistant to barbiturates but responded to magnetic coil stimulation of the motor cortex. Electrical motor cortex stimulation provided excellent relief from the pain. The second patient was a 43-year-old man who was suffering from congenital cerebral palsy for which left thalamotomy was performed two times, at the ages of 9 and 13. He began to experience intractable pain on the right side 20 years later. Although barbiturate administration was effective for pain relief, neither magnetic coil stimulation nor electrical stimulation of the motor cortex gave relief from pain.

Adult↗

PubMed1995

In vivo effect of cabergoline, a dopamine agonist, on estrogen-induced rat pituitary tumors.

Cabergoline (CG) is a dopamine agonist that inhibits the secretion of prolactin (PRL) and growth hormone. In the present study, we evaluated the in vivo effect of CG on PRL secretion and the pituitary tumor induced by estrogen. Estrogen was administered by subcutaneous injection to 4-week-old Fischer 344 rats weekly for 10 weeks to induce tumors. On the last day of estrogen administration, doses of either CG or bromocriptine (BC), 0.6 mg/kg, were administered as a single oral route or chronically, given every third day. Sera and pituitary tumors were sampled on each treatment schedule. Serum levels of PRL were measured and the pituitary glands were weighed. Immunohistological evaluation was performed by optical and electron microscopy. A single dose of CG significantly inhibited the serum levels of PRL for 6 days. Following a single dose of BC, the PRL level was significantly inhibited only at 6 hours' postadministration. The continued oral administration of CG significantly reduced both the serum PRL level and the weight of the pituitary during 15 to 60 days of treatment as compared with BC. Morphologic studies revealed that CG reduced the size of the cells and of the granules, and increased the number of granules per unit area of the cytoplasm. These findings suggest that CG inhibits the maturation of PRL secretory granules and the secretion of PRL more than its synthesis. Thus, CG induced a prolonged lowering of PRL and had a good antitumor effect on rat pituitary tumors induced by estrogen.

Animals↗

PubMed1995

Characteristics of prolactin secretion in normal and estrogen-treated pituitaries of rats at the single cell level: analysis by reverse hemolytic plaque assay.

We studied PRL release from individual pituitary cells in normal and estrogen (E2)-treated female Fischer 344 rats by means of a reverse hemolytic plaque assay. In this assay, the area of the hemolytic plaque around a pituitary cell is proportional to the amount of hormone secreted from the cell. Multimodal distribution of the plaque area was observed in normal pituitary cells, and was unchanged in the course of aging. In E2-treated pituitary cells, bimodal distribution was found. The heterogeneity of the distribution pattern (functional heterogeneity) and PRL secretion from a single pituitary cell decreased in association with the length of E2 treatment. The mean plaque area for the E2-treated pituitary cells was smaller than that for the normal pituitary cells. These results suggest that in E2-treated pituitary cells, the functional heterogeneity and PRL release from a single cell decrease as tumorigenesis progresses.

Animals↗

PubMed1995

Effect of cabergoline, a dopamine agonist, on estrogen-induced rat pituitary tumors: in vitro culture studies.

Cabergoline (CG) is a dopamine agonist that inhibits secretion of prolactin (PRL) and growth hormone. The purpose of this study was to investigate the PRL-lowering effect and antitumor effect of CG on estradiol-induced rat pituitary tumors in vitro and to elucidate these mechanisms. We compared the effects of CG with those of bromocriptine (BC) in terms of the inhibition of hormone secretion as well as antitumor effects on rat pituitary tumors. Primary cultures of dissociated pituitary tumor cells were used in these studies. A significant inhibition of prolactin (PRL) secretion was observed for both drugs within 12 h after treatment, and the inhibitory effects of CG and BC were antagonized by sulpiride or haloperidol. Inhibitory effect on PRL secretion after 12-h BC or CG pretreatment was more pronounced with CG than BC treatment at all time points. PRL secretion in group pretreated with CG was significantly suppressed at 72 h when compared to that of vehicle. Inhibition of de novo PRL synthesis was better demonstrated in the CG group. These findings suggest that CG has a higher affinity for the D2 receptor of pituitary cells as compared to BC and may preferentially inhibit PRL secretion rather than PRL production. An antitumor effect of CG has been confirmed at a lower dosage than that of BC.

Animals↗

PubMed1995

Anterior pituitary function in patients with nonfunctioning pituitary adenoma: results of longitudinal follow-up.

Studies of anterior pituitary function in patients treated for nonfunctioning pituitary adenomas have been limited by their short duration. The purpose of the present study was to examine pituitary function longitudinally among three types of patients: those with complete tumor removal (group A); those with subtotal or partial adenomectomy (group B); and those in group B who underwent additional radiation therapy (group C). The subjects were 33 patients whose anterior pituitary function was evaluated by provocative tests such as insulin induced hypoglycemia, thyrotropin releasing hormone administration test and luteinizing hormone releasing hormone administration test. They underwent preoperative evaluation and postoperative reevaluations at 2 weeks, 3 months, 6 months and annually thereafter, for over 10 years. Anterior pituitary function was restored within a year after surgery, if at all. No additional function was restored after one year from treatment. In group A, no one developed impairment of anterior pituitary function after one year from surgery. In group B, however, new impairment was noted at intervals, due to tumor regrowth. In Group C, deficiencies developed after one year, irrespective of tumor regrowth. In conclusion, lifelong endocrinological follow-up is recommended for patients receiving postoperative irradiation, and for patients with potential for tumor regrowth. On the other hand, patients with total adenomectomy may be exempted from periodic endocrinological follow-up if they do not need postoperative hormonal replacement therapy.

Adenoma↗

PubMed1995

Secretion of growth hormone (GH)-releasing hormone by GH-producing pituitary adenoma assessed by cell immunoblot analysis.

To detect growth hormone-releasing hormone (GHRH) secreted by monodispersed human GH-producing pituitary adenoma cells, the cell immunoblot assay was performed. GHRH-secreting cells were observed in 3 cases of GH-producing pituitary adenomas. The incidence of GHRH-secreting cells in the total cell populations was 0.24-3.42%. By contrast, no GHRH-secreting cells were observed in 2 cases of clinically nonfunctioning pituitary adenomas. The findings obtained by immunohistochemical studies for adenohypophysial hormones and for nuclear antigens of proliferative activity revealed that the incidence of GHRH-secreting cells is more related to the frequency of GH cells than to the proliferative activity in GH-producing pituitary adenomas.

Adenoma↗

PubMed1995

[A case report of cranial bone defect with a porencephalic cyst in an adult].

A case of cranial bone defect with porencephalic cyst in an adult was reported. A 47 year-old male was admitted with epilepsy. He had a round lytic bone defect lesion in the left frontal skull. The porencephalic cyst was under the bone defect. The mechanism of bone defect is thought to be as follows. He had received some head trauma in childhood and the frontal skull bone had fractured. The contusioned brain changed to a porencephalic cyst. The linear bone fracture may have enlarged according to the mechanism of a growing skull fracture. Persistent pulsative pressure from the porencephalic cyst toward the fractured bone edge might be able to make the bone defect oval.

Brain Diseases↗