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M Sumida

Publications and source records attributed to M Sumida.

At least 37 records · Page 2Linked to original sources
PubMed2000

The steady-state kinetics of the enzyme reaction tested by site-directed mutagenesis of hydrophobic residues (Val, Leu, and Cys) in the C-terminal alpha-helix of human adenylate kinase.

To elucidate whether the C-terminal region in human adenylate kinase participates in the interaction with the substrate (MgATP(2-) and/or AMP(2-)), hydrophobic residues (Val182, Val186, Cys187, Leu190, and Leu193) were substituted by site-directed mutagenesis and the steady-state kinetics of fifteen mutants were analyzed. A change in the hydrophobic residues in the C-terminal domain affects the affinity for substrates (K(m)), that is, not only for MgATP(2-) but also for AMP(2-), and the catalytic efficiency (k(cat)). The results obtained have led to the following conclusions: (i) Val182 may interact with both MgATP(2-) and AMP(2-) substrates, but to a greater extent with MgATP(2-), and play a role in catalysis. (ii) Val186 appears to play a functional role in catalysis by interacting with both MgATP(2-) and AMP(2-) to nearly the same extent. (iii) Cys187 appears to play a functional role in catalysis. (iv) Leu190 appears to interact with both MgATP(2-) and AMP(2-) substrates but to a greater extent with AMP(2-). (v) Leu193 appears to interact with both MgATP(2-) and AMP(2-) but to a greater extent with AMP(2-). The activity of all mutants decreased due to the change in substrate-affinity. The closer the residue is located to the C-terminal end, the more its mutation affects not only MgATP(2-) but also AMP(2-) substrate binding. The hydrophobic alterations disrupt hydrophobic interactions with substrates and that might destabilize the conformation of the active site. The more C-terminal part of the alpha-helix appears to interact with AMP, as if it has swung out and rotated to cover the adenine moieties. The C-terminal alpha-helix of human adenylate kinase appears to be essential for the interaction with adenine substrates by swinging out during catalysis.

Adenosine Monophosphate↗
PubMed2000

Sequence variation and structural conservation in the D-loop region and flanking genes of mitochondrial DNA from Japanese pond frogs.

The nucleotide sequences of the D-loop region and its flanking genes of the mitochondrial DNA (mtDNA) from Japanese pond frogs were determined by the methods of PCR, cloning, and sequencing. The frogs belonged to two species, one subspecies, and one local race. The gene arrangements adjacent to the D-loop region were analyzed. The frogs shared a unique mitochondrial gene order that was found in Rana catesbeiana; i.e., cyt b--D-loop region--tRNA(Leu(CUN))--tRNA(Thr)--tRNA(Pro)--tRNA(Phe)--12S rRNA. The arrangements of the three tRNA genes of these frogs were different from those of X. laevis, a species which has the same overall structure as in mammals. Highly repetitive sequences with repeat units (16-bp or 17-bp sequence specific for each taxon) were found in the D-loop region. The length of repetitive sequences varied from 0.6 kbp to 1.2 kbp, and caused the extensive size variation in mtDNA. Several short sequence elements such as putative TAS, OH, CSB-1, and CSB-2 were found in the D-loop region of these frogs. The sequences of these short regulatory elements were conserved in R. catesbeiana, X. laevis, and also in human. The comparison of sequence divergences of the D-loop region and its adjacent genes among various taxa revealed that the rates of nucleotide substitutions depend on genes. The nucleotide sequences of the 3'-side segment of the D-loop region were the most variable among taxa, whereas those of the tRNA and 12S rRNA genes were the most conservative.

Animals↗
PubMed2000

[A case of idiopathic cranial hypertrophic pachymeningitis presenting Tolosa-Hunt syndrome].

A 48-year-old female was seen because of left orbital pain. The neurological findings were normal at her first visit. She presented temporary double vision during conservative period. Plain CT revealed no mass around the sellar region. Enhanced CT revealed enhanced mass in the left cavernous sinus. MRI revealed low intensity lesion on both T1 and T2 weighted images. Enhanced MRI showed strongly enhanced mass extended from the left cavernous sinus to the dura of sellar floor, the contralateral cavernous sinus, and cerebellar tentorium. Angiography showed stenosis of the left internal cerebral artery. Biopsy from the dura of the tentorium was performed via anterior temporal approach. Abundant collagen fibers with hyalinization were seen in the thickened dura. A final diagnosis of idiopathic cranial hypertrophic pachymeningitis presenting Tolosa-Hunt syndrome was made. Symptoms were free just after the surgery, however, the regrowth of the tentorial lesion was found on MRI after one year. The size of the lesion decreased after administration of steroid.

Female↗
PubMed2000

Substituted 3-phenylsulfonylquinazoline-2,4-dione derivatives as novel nonpeptide inhibitors of human heart chymase.

A series of 3-phenylsulfonylquinazoline-2,4-dione derivatives have been synthesized and evaluated for their ability to inhibit human heart chymase. The structure-activity relationship studies on these compounds gave the following results. The phenyl moiety of quinazoline participates in a hydrophobic interaction where an optimum size is required. In this moiety, 7-chloroquinazoline is the best moiety for inhibiting chymase, chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted with hydrophobic electron-withdrawing groups at the 4-position potentiated the activity. Anthranil moiety also enhanced the activity. Pyridylmethyl and N-pyridylacetamide at the 1-position gave an IC50 in the order of 10(-8)M. Molecular modeling studies on the interaction of 7-chloro-3-(4-chlorophenylsulfonyl) quinazoline-2,4(1H, 3H)-dione (4) with the active site of human heart chymase suggested that the phenyl moiety of quinazoline interacts with the hydrophobic P1 pocket, the 3-phenylsulfonyl moiety resides in the S1'-S2' subsites, the moiety at the 1-position locates in the S2-S3 subsites and the 4-carbonyl and 3-sulfonyl group interact with the oxyanion hole and the His57 side-chain of chymase, respectively.

Chymases↗
PubMed1999

Purification, characterization, and application of an acid urease from Arthrobacter mobilis.

It has been shown that urea in fermented beverages and foods can serve as a precursor of ethylcarbamate, a potential carcinogen, and acid urease is an effective agent for removing urea in such products. We describe herein the purification and characterization of a novel acid urease from Arthrobacter mobilis SAM 0752 and show its unique application for the removal of urea from fermented beverages using the Japanese rice wine, sake, as an example. The purified acid urease showed an optimum pH for activity at pH 4.2. The enzyme exhibited an apparent K(m) for urea of 3.0 mM and a Vmax of 2370 mumol of urea per mg and min at 37 degrees C and pH 4.2. Gel permeation chromatographic and sodium dodecyl sulfate gel electrophoretic analyses showed that the enzyme has an apparent native molecular weight (M(r)) of 290,000 and consisted of three types of subunit proteins (M(r), 67,000, 16,600, 14,100) denoted by alpha, beta, and gamma. The most probable stoichiometry of the subunits was estimated to be alpha: beta: gamma = 1:1:1, suggesting the enzyme subunit structure of (alpha beta gamma)3. The enzyme also existed as an aggregated form with an M(r) of 580,000. The purified enzyme contained 2 g-atom of nickel per alpha beta gamma unit of the enzyme. Enzyme activity was inhibited by acetohydroxamic acid, HgCl2, and CuCl2. The isoelectric point of the native enzyme was estimated by gel electrofocusing to be 6.8. Urea (50 ppm), which was exogenously added to sake (pH 4.4, 17 +/- 1% (v/v) ethanol), was completely decomposed by incubation with the enzyme (0.09 U ml-1) at 15 degrees C for 13 days. The enzyme was unstable at temperatures higher than 65 degrees C and pHs lower than 4, and was completely inactivated under the conditions of a pasteurization step involved in the traditional sake-making processes. These results indicate that the enzyme is applicable to the elimination of urea in fermented beverages with minimal modification to the conventional process.

Alcoholic Beverages↗
PubMed1999

Sex-determining mechanism in Buergeria buergeri (Anura, Rhacophoridae). III. Does the ZZW triploid frog become female or male?

Both triploids and gynogenetic diploids (GDs) were produced to clarify the relationship between the sex-chromosome constitution and the expression of sex in the common bell-ring frog, Buergeria buergeri. The sex differentiation of triploids in B. buergeri is quite remarkable. Triploid frogs consisted of three sex genotypes, ZZZ, ZWW and ZZW. All ZZZ triploids were males, and all ZWW triploids were females. It is very interesting that half of the ZZW triploids became female, and the other half became male. The GD frogs consisted of two sex genotypes, ZW and ZZ, which did not differ from the controls in sex differentiation. Since the ratios of ZZ and ZW eggs were significantly different among female parents, it is assumed that most (approximately 80-90%) of the eggs made pre-reductional division in some females and post-reductional division in others during meiosis. It seems that ZW eggs were produced by the occurrence of recombination between the centromere and the sex-determining genes in B. buergeri. It was also found that the number of Z chromosomes in each cell of these triploids and GDs agreed with that of the nucleoli in each cell.

Animals↗
PubMed1999

Prevention by methylprednisolone of increased circulating tumor necrosis factor-alpha levels and lung injury associated with systemic inflammatory response syndrome due to intraperitoneal hyperthermia.

UNLABELLED: We previously demonstrated that intraperitoneal hyperthermic perfusion (IPHP), which is performed clinically as a treatment for patients with advanced gastrointestinal cancer, can lead to increased serum tumor necrosis factor-alpha (TNF-alpha), systemic inflammatory response syndrome (SIRS), and acute lung injury. Glucocorticoids inhibit the production and actions of TNF-alpha. We investigated whether pretreatment with methylprednisolone (MPS) may modulate serum TNF-alpha and lung injury in patients subjected to IPHP. Serum TNF-alpha was not detected in the patients pretreated with MPS, whereas serum TNF-alpha increased in the control patients (45.7 +/- 8.3 pg/mL, mean +/- SEM) after IPHP. Postoperative lung injury scores were significantly lower in patients pretreated with MPS than in the control patients (P < 0.001). IMPLICATIONS: Pretreatment with methylprednisolone attenuates the increase in circulating tumor necrosis factor-alpha and prevents lung injury in this systemic inflammatory syndrome due to intraperitoneal hyperthermic perfusion.

Adult↗
PubMed1999

High incidence of meningioma among Hiroshima atomic bomb survivors.

Since the atomic bomb explosions in Hiroshima and Nagasaki, high incidences of leukemia, thyroid cancer and other tumors have been reported as atomic bomb-induced tumors. We investigated the incidence of meningioma among Hiroshima atomic bomb survivors. Sixty-eight patients surgically treated for meningioma who had been within 2.0 km of the hypocenter of the explosion were identified. Six hundred and seven non-exposed patients with meningioma were also studied. Treatment dates were from 1975 to 1992. The incidences of meningioma among 68 subjects within 2.0 km and 607 non-exposed patients were 8.7 and 3.0 cases per 10(5) persons per year, respectively. The incidences of meningioma among the survivors of Hiroshima in 5-year intervals since 1975 were 5.3, 7.4, 10.1, and 14.9, respectively. The incidences of meningioma classified by distances from the hypocenter of 1.5-2.0 km, 1.0-1.5 km and less than 1.0 km were 6.3, 7.6 and 20.0, respectively. The incidences of meningioma classified by doses to the brain of 0-0.099 Sv, 0.1-0.99 Sv and more than 1.0 Sv were 7.7, 9.2 and 18.2, respectively. The incidence of meningioma among Hiroshima atomic bomb survivors has increased since 1975. There was a significant correlation between the incidence and the dose of radiation to the brain. The present findings strongly suggest that meningioma is one of the tumors induced by atomic bombing in Hiroshima.

Brain↗
PubMed1999

Symptomatic Rathke's cleft cyst coexisting with central diabetes insipidus and hypophysitis: case report.

We describe a 48-year-old female with acute onset of central diabetes insipidus followed by mild anterior pituitary dysfunction. Magnetic resonance imaging (MRI) revealed enlargement of the hypophysis-infundibulum accompanied by a cystic component. She underwent a transsphenoidal exploration of the sella turcica. Histological examination showed foreign body type xanthogranulomatous inflammation in the neurohypophysis which might have been caused by rupture of a Rathke's cleft cyst. The MRI abnormalities and anterior pituitary dysfunction improved after a short course of corticosteroid administration, but the diabetes insipidus persisted. The histological findings in this case indicated the site of RCC rupture and the direction of the progression of RCC induced neurohypophysitis and adenohypophysitis.

Cysts↗
PubMed1999

Dural sinus thrombosis in a patient with protein S deficiency--case report.

A 23-year-old female presented with dural sinus thrombosis caused by protein S deficiency. She suffered superior sagittal sinus thrombosis 6 days after delivering her first child. Past history showed deep vein thrombosis at the age of 20. While conservative management was initiated because of the potential risk of increasing intracranial hemorrhage, several hours later she deteriorated rapidly because of severe brain swelling with massive hemorrhage. The patient died despite surgical decompression. Autopsy disclosed organized thrombus in the superior sagittal and transverse sinuses. Although the total concentration of protein S was normal, the free protein S concentration and protein S activity were decreased. Protein S deficiency is a rare cause of dural sinus thrombosis, but is associated with a high mortality rate, so accurate diagnosis and urgent intervention are required.

Adult↗
PubMed1999

The relationship between magnetic resonance imaging findings and clinical manifestations of hypothalamic hamartoma.

OBJECT: Hypothalamic hamartoma is generally diagnosed based on its magnetic resonance (MR) imaging characteristics and the patient's clinical symptoms, but the relationship between the neuroradiological findings and clinical presentation has never been fully investigated. In this retrospective study the authors sought to determine this relationship. METHODS: The authors classified 11 cases of hypothalamic hamartoma into two categories based on the MR findings. Seven cases were the "parahypothalamic type," in which the hamartoma is only attached to the floor of the third ventricle or suspended from the floor by a peduncle. Four cases were the "intrahypothalamic type," in which the hamartoma involved or was enveloped by the hypothalamus and the tumor distorted the third ventricle. Six patients with the parahypothalamic type exhibited precocious puberty, which was controlled by a luteinizing hormone-releasing hormone analog, and one patient was asymptomatic. No seizures or mental retardation were observed in this group. All patients with the intrahypothalamic type had medically intractable seizures, and precocious puberty was seen in one. Severe mental retardation and behavioral disorders including aggressiveness were seen in two patients. The seizures were controlled in only one patient, in whom stereotactically targeted irradiation of the lesion was performed. This topology/symptom relationship was reconfirmed in a review of 61 reported cases of hamartoma, in which the MR findings were clearly described. The parahypothalamic type is generally associated with precocious puberty but is unaccompanied by seizures or developmental delay, whereas the intrahypothalamic type is generally associated with seizures. Two thirds of patients with the latter experience developmental delays, and half also exhibit precocious puberty. CONCLUSIONS: Classification of hypothalamic hamartomas into these two categories based on MR findings resulted in a clear correlation between symptoms and the subsequent clinical course.

Adolescent↗
PubMed1999

[Cerebral metastasis from a renal cell carcinoma more than 10 years after nephrectomy: report of two cases].

The authors report two cases with renal cell carcinoma (RCC) metastatic to the brain more than 10 years after nephrectomy. Case 1: An eighty-six-year-old female, on whom nephrectomy had been performed 12 years before, complained of alexia. Computed tomography (CT) revealed ring enhancement in the left temporoparietal region. Total removal of the brain tumor and irradiation of 18 Gy during surgery was performed. Histological examination showed metastatic brain tumor from RCC. The postoperative course was excellent. In the postoperative examination lung metastasis was found. Case 2: A sixty-seven-year-old male, on whom nephrectomy had been performed 15 years before, presented with right hemiparesis, aphasia and convulsion. CT showed two enhanced lesions, one of which accompanied with a hematoma in the left frontal lobe. Chest X-ray showed a coin lesion in the right lower lobe. Total removal of brain tumors was performed and 18 Gy irradiation was administered during surgery. Histological study revealed RCC. However, 3 months after surgery, a new lesion was recognized in the opposite hemisphere. The long interval of latency may be attributed to the slow-growing characteristic of renal cell carcinoma and the fact that renal cell carcinoma is under the influence of host immunity. Surgical treatment is recommended for patients who develop a solitary metastatic lesion or in whom other lesions are controlled and remain in a stable condition.

Aged↗
PubMed1999

[A case of recurrent-rupture dermoid cyst].

A 58-year-old man was seen because of general convulsions. The neurological findings were normal at his first visit, but CT revealed a low density mass in the right hypothalamus with calcification. T1-weighted image revealed multiple high intensity lesions in the subarachnoid space. Only anti-epileptic drugs were prescribed. He was readmitted one year later because of a traffic accident due to convulsions. CT and MRI revealed other new lesions in the bilateral anterior horn. After four uneventful years, follow-up CT revealed a dilation of the third ventricle. MRI using the fat suppression method showed enhancement around the main tumor and the wall of the lateral ventricles and stenosis of the aqueduct. Right frontotemporal craniotomy was performed. Thickening of the arachnoids and floating lipid droplets were seen in the sub-arachnoid space. A yellowish tumor was found in the suprasellar region, adhering to the internal carotid artery. The tumor contained soft yellowish tissue and hair. Only partial removal was carried out because of severe adhesion to perforators. The lamina terminalis was opened after tumor removal. The postoperative course was uneventful except for transient diabetes insipidus.

Brain Neoplasms↗
PubMed1999

[A case of hemorrhagic non traumatic arteriovenous fistula of the scalp].

Arteriovenous malformation of the scalp in an uncommon disease and treatment for this lesion is difficult and controversial. A twenty-three-year-old male, who reported no history of head trauma, presented with spontaneous hemorrhage from the left temporal scalp. Neurologically he was normal except the tinnitus. Left external carotid angiography demonstrated arteriovenous malformation fed by the superior temporal and posterior auricular arteries. A dilated tortuous occipital artery was also recognized. The lesions were able to be surgically resected, alleviating intraoperative massive hemorrhage by proximal temporary occlusion of the external carotid artery at the left neck. Small feeding arteries from the meningeal artery which were not recognized on preoperative angiography were found at surgery. The arteriovenous fistula was successfully resected without any cosmetic problem.

Adult↗
PubMed1998

Alkaline lipase from brain: is it the same enzyme as pancreatic lipase from pancreas?

A new alkaline lipase was detected in rat brain and its properties were compared with those of the well-characterized pancreatic lipase and pancreatic lipase-related protein 2. The activity of the alkaline lipase was determined using trioleoylglycerol emulsion at pH 8.0. Subcellular fractions were prepared from brain homogenates by differential centrifugation. Lipase activities of the cytosolic fraction (the supernatant obtained by differential centrifugation of 100,000g) were stimulated by addition of colipase and bile salts and inhibited by addition of an antibody against rat pancreatic lipase. The partially purified enzyme had an isoelectric point of pH 6.8, which was identical to that found for rat pancreatic lipase. The enzyme had interfacial activation and dependence on colipase in the presence of bile salts. The enzyme had no measurable phospholipase A activity. The band produced by the enzyme on SDS-polyacrylamide gel electrophoresis was identical to that of the rat pancreatic lipase when detected by immunoblotting analysis using an antibody against pancreatic lipase. These results show that pancreatic lipase such as alkaline lipase is in rat brain.

Animals↗
PubMed1998

Demonstration of the optic pathway in sellar/juxtasellar tumours with visual disturbance on MR imaging.

OBJECTIVE: To prospectively compare the demonstration of the intracranial optic pathway in patients with sellar/juxtasellar tumours and with clinical evidence of visual disturbance using either spoiled gradient recalled acquisition in steady state (SPGR) or conventional spin echo (CSE) T1-weighted imaging. MATERIALS AND METHODS: We studied 108 patients with sellar/juxtasellar tumours presenting visual disturbance. Visualization of the optic pathway (nerves, chiasm, tracts) was compared between CSE T1-weighted coronal image and SPGR coronal image. In 18 patients, SPGR imaging was performed before and after administration of Gd-DTPA and visualization of the optic pathway was compared. RESULTS: On CSE T1-weighted coronal images of 108 patients with visual disturbance, the rates for visualization of the optic nerves, chiasms and tracts were 50%, 77.8% and 89.8% respectively. In contrast, on SPGR coronal image the rates were 80.6%, 96.3% and 92.6% respectively. The rates of visualization of the optic pathway were greater in non-enhanced that in those with enhancement. The rates of visualization in patients with recurrent tumours were less than those in patients with primary tumours. The rate of visualization of optic nerves in patients with meningioma was less than in patients with pituitary adenoma, craniopharyngioma or Rathke cleft cyst. CONCLUSION: The rate of visualization of optic pathway structures on SPGR imaging (without enhancement) is greater than that on CSE T1-weighted imaging. It is important to understand the accurate position of the optic pathways with using new MR modality especially in surgical planning for lesions around the sella turcica.

Adolescent↗
PubMed1998

Site-directed mutagenesis and steady-state kinetic analysis of mutant enzymes of human adenylate kinase.

Site-directed mutagenesis of human adenylate kinase (AK) was carried out on residues His36, Lys55, and the C-terminal segment (Val182, V186, and Leu193). Five mutants [(H36T, K55G, V182G, V186S, and L193Stop (deletion of residues 193-194)] were generated and analyzed by steady-state kinetics. H36T, K55G, and L193Stop mutants showed an increase of K(m) values (19.8-, 19.7-, and 11.3-fold) for AMP2- compared to that for the wild-type enzyme, and these residues appeared to interact with AMP2-. V182G showed an increased K(m) value (7.4-fold) for MgATP2-. Therefore, V182 may be essential for interaction with MgATP2-. V186S increased the K(m) value (7.0- and 7.5-fold) for MgATP2- and AMP2-. V186 may thus interact with both substrates. The C-terminal domain of AK appears to be essential for MgATP2- and AMP2- binding.

Adenylate Kinase↗