PubMed Health⌕ Search

Biomedical subjects

N Sakata

Publications and source records attributed to N Sakata.

At least 145 records · Page 8Linked to original sources
PubMed1990

[Prognosis of childhood mediastinal lymphoma].

Between 1973 and 1989, 16 children with non-Hodgkins lymphoma (NHL) with a mediastinal mass (MM) were treated at our institution with multi-agent chemotherapy and radiotherapy. They also received central nervous system (CNS) prophylaxis including intrathecal methotrexate administration (14 cases) and cranial irradiation (7 cases). Twelve were boys and 4 girls. Median age was 11 +/- 3. One patient died of air way obstruction one day after admission. Fourteen of 15 patients entered into complete remission (CR) and one patient partial remission. Five remains in CR 7 to 175 months after diagnosis (median 76 months). Nine patients relapsed in the bone marrow (3 cases), CNS (3), testicles (1), neck lymph node (1) and bones plus kidneys (1). Of these, 7 patients died within 13 months after initial relapse. The disease free survival (DFS) and overall survival of all patients were 27% and 33%, respectively. Analysis of the prognostic factors among patients with MM+ -NHL revealed that the serum LDH level below 1,000IU/l was a good prognostic sign. Other factors such as age, stage, initial WBC count, size of MM and response of the MM to the initial treatment did not correlate with DFS. Because of its rarity and the poor treatment result, we need more aggressive treatment program by a multiinstitutional study for MM+ -NHL.

Adolescent↗
PubMed1989

Intravenous flunitrazepam for status epilepticus.

Flunitrazepam (FZP) was administered intravenously, with success, to two patients with status epilepticus. Case 1 was a patient with a tonic-clonic status epilepticus. Intravenous phenytoin had no effect. Case 2 had minor status epilepticus. With the intravenous administration of FZP, diluted 1:10 with distilled water at a dose of 0.03 mg/kg at a slow rate, both patients were relieved of the status epilepticus. Unlike diazepam, FZP neither looks cloudy when diluted with distilled water nor causes angialgia. No disturbances in circulation or respiration occurred. Considering that FZP has a strong anticonvulsant action on status epilepticus, it can be expected to be a useful therapeutic agent for status epilepticus in infants and children.

Child↗
PubMed1989

Effects of calcium antagonists and free radical scavengers on myocardial ischemia and reperfusion injury: evaluation by 31P-NMR spectroscopy.

The Langendorff perfused rat heart was used to investigate whether myocardial damage during ischemia and reperfusion could be protected by free radical scavengers, calcium antagonist and adenosine. Myocardial high energy phosphates were measured by phosphorus-31 NMR spectroscopy during normal perfusion, 20 min of ischemia and 20 min of reperfusion. In hearts, which were treated both with free radical scavengers (FRS) (Superoxide dismutase): 24 IU/ml and catalase 22 IU/ml) and verapamil (10(-7) M), beta-ATP was significantly higher than that of FRS at the end of ischemia. However, beta-ATP recovered only to 83% of baseline value at the end of reperfusion. In view of myocardial metabolism, verapamil treated hearts were good for recovery of creatine phosphate (PCr) but not ATP at the end of reperfusion. Hearts which were treated with only adenosine did not differ from control hearts. However, when hearts were treated with both verapamil and adenosine (10(-4) M), recovery of both ATP and PCr content was significantly greater than that of control hearts. These results suggested that pretreatment with both verapamil and adenosine before and after global ischemia could protect ischemic myocardium, but, further studies are necessary to clarify the precise mechanism of protection.

Adenosine↗
PubMed1989

Nucleotide sequence of the macromomycin apoprotein gene and its expression in Streptomyces macromomyceticus.

A 1.6 kb Sph I-Sac I DNA fragment from Streptomyces macromomyceticus, expected to include the macromomycin (MCM) apoprotein gene, was sequenced. The fragment (1,556 bp) was found to include a putative promoter, an ORF directing pre-apoprotein which should be split into the leader peptide (Met1 to Gly32) and the MCM apoprotein (Ala33 to Ala144), and a putative terminator. The amino acid sequence deduced from the base sequence of the DNA is consistent with the amino acid sequence previously determined by the Edman degradation and other procedures applied to the protein, except base sequence AAC coding for Asn was found rather than Asp111 previously reported. The GC content of the 3rd letters throughout the ORF was 92% in contrast to the sum of the first and the second letters, 62%. There was a low GC content stretch of 20 bp (30% GC) at about 120 bp upstream of the ORF. The Pst I-Sph I 620 bp fragment including the low GC content stretch showed promoter activity when subcloned in a promoter probe vector. About 700 nucleotides long mRNA, which is long enough to span the ORF and the bordering regions, was identified using the Northern blot analysis. A primer extension experiment showed that the transcriptional starting point was A at 89 bp upstream of the ORF. Dot blot analysis of expression of MCM apoprotein gene indicated that the gene was expressed nearly constitutively, while production of holo MCM (the complex consisting of MCM apoprotein and a specific chromophore) depended greatly on culture conditions.

Amino Acid Sequence↗
PubMed1989

Heterogeneity of anti-B monoclonal antibodies in reactivity to erythrocytes and saliva samples from various B secretor individuals.

In order to study the heterogeneity of anti-B monoclonal antibodies under the same conditions, twelve different types were produced from a mouse immunized with human blood group B erythrocytes, all of which were IgM antibodies that exhibited strong and specific agglutination activity for normal blood group B erythrocytes. However, analysis of the agglutination titer for blood group B2, B3, and rabbit erythrocytes revealed some qualitative differences among these antibodies. These differences were further clarified by comparing the inhibition pattern of the monoclonal antibody with saliva from B individuals, with that of ordinary human antiserum to show remarkable differences among individuals.

ABO Blood-Group System↗
PubMed1988

"Osmiophilic elastolysis" of peripheral organ arteries in patients with Marfan's syndrome.

Electron microscopic examinations were performed on systemic muscle-type arteries from two teen-age girls with Marfan's syndrome. In the peripheral organ arteries, the internal elastic lamella revealed a feature tentatively termed "osmiophilic elastolysis". The lytic changes appeared segmentally in the form of electron-dense fragments, and were partly absorbed. Regenerated elastin had a normal structure and surrounded the elastolytic lesions. The same changes were observed in the newly formed small areas of elastin in the thickened intima. The remaining elastic lamella in the affected region contained numerous fine electron-dense granules. Intercellular substances, including collagen fibrils and proteoglycan, other than elastic fibers, were increased secondarily in the elastolytic lesions without any evidence of ultrastructural abnormality. Medical smooth muscle cells making contact with the elastolytic lesions were necrosed and absorbed, and smooth muscle cells in a state of synthesis were increased in the adjacent areas. Abnormal elastogenesis, which showed no remarkable changes macroscopically or light microscopically, was systemic but segmental in the peripheral organ arteries, and regeneration of the structurally normal elastin was concurrent with elastolysis. These events were diagnostic for Marfan's syndrome, and cannot be explained by the conventional theory of elastogenetic enzymic deficiency.

Adolescent↗
PubMed1988

Vortex generation in pulsatile flow through arterial bifurcation models including the human carotid artery.

Visualization experiments were performed to elucidate the complicated flow pattern in pulsatile flow through arterial bifurcations. Human common carotid arteries, which were made transparent, and glass-models simulating Y- and T-shaped bifurcations were used. Pulsatile flow with wave forms similar to those of arterial flow was generated with a piston pump, elastic tube, airchamber, and valves controlling the outflow resistance. Helically recirculating flow with a pattern similar to that of the horseshoe vortex produced around wall-based protuberances in circular tubes was observed in pulsatile flow through all the bifurcations used in the present study. This flow type, which we shall refer to as the horseshoe vortex, has also been demonstrated to occur at the human common carotid bifurcation in steady flow with Reynolds numbers above 100. Time-varying flows also produced the horseshoe vortex mostly during the decelerating phase. Fluid particles of dye solution approaching the bifurcation apex diverged, divided into two directions perpendicularly, and then showed helical motion representing the horseshoe vortex formation. While this helical flow was produced, the stagnation points appeared on the wall upstream of the apex. Their position was dependent upon the flow distribution ratio between the branches in the individual arteries. The region affected by the horseshoe vortex was smaller during pulsatile flow than during steady flow. Lowering the Reynolds number together with the Womersley number weakened the intensity of helical flow. A separation bubble, resulting from the divergence or wall roughness, was observed at the outer or inner wall of the branch vessels and made the flow more complicated.

Adult↗
PubMed1988

Localization of atherosclerotic lesions in the curving sites of human internal carotid arteries.

We studied the distribution of the early atherosclerotic lesions in the curving sites of the human internal carotid arteries composed of the carotid siphon portion (part I) and carotid canal portion (part II). These early atherosclerotic lesions included a localized cloudy thickening with pallor, slight elevation, a non-fibrotic lesion and gray-white or yellowish-white, firm, elevated fibrous plaques. These lesions had the same pattern-distribution in each curving artery. Both were located in the distal regions from the middle of the inner curvature of parts I and II, where eddying fluid motions and directional change in the wall shear stress were considered to occur. In part I, there was a localized cloudy thickening in the younger subjects (average age: 22.8 years) rather than fibrous plaques (average age: 63.3 years). A positive correlation between the extent of the surface areas involved with fibrous plaques and the age of subjects was found in parts I and II. The extent of the surface areas involved with fibrous plaques was significantly greater in part I (26.9%) than in part II (7.85%). The radius of curvature was shorter in the former than in the latter. These results suggest that hemodynamic factors associated with flow in the curving sites of arteries may be important for the localization and progression of atherosclerotic lesions.

Adolescent↗
PubMed1988

Cloning of macromomycin apoprotein gene from Streptomyces macromomyceticus by use of 50-mer deoxynucleotide probes.

A mixed probe consisting of two synthetic deoxynucleotides (52 and 54 mers referred to as 50-mer) with arbitrarily chosen C or G for the third letters was prepared based on the amino acid sequences No. 31-48 and No. 72-90 of macromomycin (MCM) apoprotein and successfully used to clone the MCM apoprotein gene. Digestion with Sph I of total DNA of MCM-producing Streptomyces macromomyceticus M480-M1 yielded a 2.6-kb fragment that hybridized strongly to the probes. The hybridized probe was stable to washing with 3 x SSC at 75 degrees C. Radioactivity derived from the hybridized probe was comparable to that expected theoretically from hybridization between the probe and the true target sequence. The 2.6-kb fragment was cloned into Escherichia coli RR1 with pBR322 and subsequently subcloned into Streptomyces lividans TK21 with pIJ702. Nucleotide sequence analysis of the cloned fragment verified the existence of the sequence corresponding to the amino acid sequence of MCM apoprotein and about 90% homologies with the probes. Thus, the use of relatively long deoxynucleotide probes with arbitrarily chosen C or G for the third letters will be advantageous in cloning Streptomyces protein genes where more than 90% of the third letters have been known to be C or G. In addition, theoretical diagnosis of hybridization should be a great help to distinguish true positives from false ones.

Amino Acid Sequence↗
PubMed1988

Terpentecin, an inhibitor of DNA synthesis.

Terpentecin at a concentration of 0.78 microgram/ml decreased the number of viable cells of Escherichia coli NIHJ to less than one thousandth the starting number in an hour when added to an exponentially growing culture in a nutrient broth. During this time, the turbidity of the cell suspension kept increasing as fast as the control. Microscopic inspection of the cells exposed to terpentecin under these conditions revealed that the cells were elongated. Terpentecin at a concentration of 6.25 micrograms/ml inhibited incorporation of [14C]thymidine into the acid-insoluble material of cells of E. coli NIHJ by 70% in 30 minutes in contrast to little or no inhibition of the incorporation of [14C]uridine or [14C]leucine. Under similar conditions, terpentecin did not inhibit either membrane transport (uptake) of [14C]thymidine into the cells or the metabolic conversion of the precursor into various cellular acid-soluble components. Terpentecin at a higher concentration (70 micrograms/ml) inhibited by 40% in 30 minutes the incorporation of [methyl-3H]thymidine triphosphate into the DNA fraction of toluene-treated cells of E. coli JE6296 (pol A-). Terpentecin showed stronger antibacterial activities against Bacillus subtilis M45T (rec-) and E. coli BE1121 (rec A-) than against their corresponding wild type strains. However, terpentecin showed no mutagenicity by the Ames test with Salmonella typhimurium strains TA100, TA98, TA92, TA1538, TA1537 and TA1535, and with E. coli WP2 (uvr A). Terpentecin at a lower concentration (0.07 micrograms/ml) inhibited growth in vitro of mouse leukemia L1210 cells by 50%. With the mammalian cells again the incorporation of [14C]thymidine into the acid-insoluble cell material was inhibited more strongly than incorporation of [14C]uridine and [14C]leucine. There was no sign of mutagenicity by the micronucleus test using mice.

Animals↗
PubMed1986

Effects of antifibrotic substances on pancreatic fibrosis following acute necrotizing pancreatitis.

This study was designed to search for a way to inhibit pancreatic fibrosis following acute pancreatitis. Experimental necrotizing pancreatitis was induced by a freezing procedure in the pancreas of male Wistar rats. After the freezing procedure, the rats were divided into 3 groups: nothing addition was done to the control group, while the other 2 groups received daily intraperitoneal administration of antifibrotic substances (colchicine or L-azetidine-2-carboxylic acid (AZC)) for 6 weeks. Pancreatic enzymes in the serum were not markedly influenced by administration of antifibrotic substances, and there were no differences in the ratios of dry to wet weights of the pancreas between groups with and without these drugs. After freezing, the hydroxyproline levels in the pancreas of the control group increased from 1 to 4 weeks and then decreased during the 5th and 6th weeks. All groups receiving colchicine or AZC exhibited a significant decrease in the hydroxyproline levels at 2 to 4 weeks compared with the control group (P less than 0.01). Histological examination also showed the inhibition of pancreatic fibrosis, agreeing with changes in the hydroxyproline levels in groups receiving colchicine or AZC. These results suggest that administration of antifibrotic substances, colchicine and AZC, have the possibility of inhibiting pancreatic fibrosis following acute pancreatitis.

Animals↗
PubMed1986

Biosynthesis of valanimycin.

In the biosynthesis of valanimycin, valine is mostly incorporated into the isobutyl moiety of the antibiotic. The alpha-substituted acrylic moiety of valanimycin is derived from alanine. However, a part of alanine is metabolized into valine, thus incorporated also into the isobutyl moiety. Anaerobic conditions and some reducing agents strongly inhibit the biosynthesis.

Alanine↗