Search PubMed⌕ Search

Biomedical subjects

T Tsuzuki

Publications and source records attributed to T Tsuzuki.

At least 181 records · Page 10Linked to original sources
PubMed1985

Molecular structures of mitochondrial-DNA-like sequences in human nuclear DNA.

Two lambda phage clones carrying mitochondrial-DNA-like (mtDNA-like) sequences isolated from a human gene library were named Lm E-1 and Lm C-2, and their DNA structures were characterized. Lm E-1 contains about 0.4 kb DNA homologous to the 5' portion of the mitochondrial 16S ribosomal RNA (rRNA) gene and Lm C-2, a 1.6 kb DNA homologous to the 3' portion of the 12S rRNA gene and to almost all of the 16S rRNA gene. Comparisons of their nucleotide sequences with those of the corresponding regions of the human mtDNA revealed no detectable DNA rearrangement and their homologies to the human mtDNA are 84% and 80%, respectively. There are neither terminal repeats in the nuclear mtDNA-like sequences nor duplications of the nuclear DNAs flanking the mtDNA-like sequences. Evolutionary relationship between these two human nuclear mtDNA-like sequences and the human and bovine mtDNAs is discussed.

Animals↗
PubMed1985

Insertion of a long KpnI family member within a mitochondrial-DNA-like sequence present in the human nuclear genome.

Structural analysis of a phage lambda Charon 4A clone carrying one of the human nuclear mitochondrial(mut)-DNA-like sequences revealed that a KpnI-family member (KpnI 5.5-kb DNA) is inserted within this sequence. The inserted KpnI 5.5-kb DNA contains several possible polyadenylation signal sequences followed by an A-rich sequence at its 3' end and is flanked by perfect 13-bp direct repeats of the duplicated mtDNA-like sequences. These structures strongly suggest that the KpnI 5.5-kb DNA is a mobile element. Comparison of the 5' terminal sequences of the KpnI 5.5-kb DNA and four other long KpnI-family DNAs so far examined, using the predicted general promoter sequence for eukaryotic tRNAs, indicates that they contain the consensus sequences for the split internal RNA polymerase III control region.

Base Sequence↗
PubMed1985

Heat resistance, spore germination, and enterotoxigenicity of Clostridium perfringens.

Heat resistance at 95 C, heat activation at 75 C, and germination response were determined for spores of 10 serotype strains of Clostridium perfringens type A, including five heat-resistant and five heat-sensitive strains. The D95-values ranged from 17.6 to 63.0 and from 1.3 to 2.8 for the heat-resistant and the heat-sensitive strains, respectively. The heat-activation values, the ratios between the heated and unheated viable counts of spore suspensions, ranged from 0.0035 to 0.65 and from 6.5 to 60.0 for the heat-sensitive and the heat-resistant strains, respectively. Spores of these strains were divided into two distinct germination types on the basis of their germination response; spores of the heat-resistant strains germinated in KC1 medium after heat activation (K-type), and spores of the heat-sensitive strains germinated in a mixture of L-alanine, inosine, and CaCl2 in the presence of CO2 without heat activation (A-type). The strains were tested for enterotoxigenicity by a reversed passive latex-agglutination (RPLA) test. All the heat-resistant strains were RPLA-positive, whereas the heat-sensitive strains were all RPLA-negative. A total of 37 strains of the organism isolated from food-poisoning outbreaks were tested for spore germination and enterotoxin formation. All of the 20 heat-resistant strains showed K-type spore germination and, except for three strains, were RPLA-positive, whereas all of the 17 heat-sensitive strains showed A-type spore germination and, except for only one strain, were RPLA-negative.

Alanine↗
PubMed1984

Energy-dependent activation of spore-lytic enzyme precursor by germinated spores of Clostridium perfringens.

A precursor of the spore-lytic enzyme of Clostridium perfringens was extracted with alkali from dormant spores of the organism. The enzyme precursor was activated by incubating it with germinated spores which had been treated with alkali. The activation was greatly enhanced by the addition of 3-phosphoglycerate, suggesting that the conversion of precursor to active enzyme depends on endogenous energy-producing metabolism during germination.

Clostridium perfringens↗
PubMed1984

Interruption of a human nuclear sequence homologous to mitochondrial DNA by a member of the KpnI 1.8 kb family.

We reported that several DNA sequences homologous to mitochondrial DNA (mtDNA) are present in the human nuclear genome (Tsuzuki et al. (1983) Gene 25, 223-229). Detailed Southern blot analyses revealed that one of such sequences is interrupted by a repetitive sequence about 1.8 kb long, and that the insert is one member of the dispersed repeated DNA sequences of the KpnI 1.8 kb family. Nucleotide sequence analysis showed that the KpnI 1.8 kb DNA is flanked with imperfect 15-base pair (bp) direct repeats of mtDNA. This KpnI 1.8 kb DNA has an A-rich sequence at its 3'-end, and has a considerable homology with one of the published cDNA sequences homologous to one of the human KpnI families and also to one of the African green monkey KpnI families, KpnI-LS1. These structural features suggest that the KpnI 1.8 kb DNA is a movable element and is inserted within the mtDNA-like sequence by an RNA-mediated process.

Animals↗
PubMed1984

Hepatic resection in 125 patients.

Hepatic resection was performed in 125 patients. Ninety-three of the 125 patients had malignant neoplasms; primary liver carcinoma in 61, metastatic liver carcinoma in 15, carcinoma of the bifurcation of the hepatic ducts in 16, and carcinoma of the gallbladder in one. Performance of hepatic resection was complicated by the presence of liver cirrhosis and jaundice in 42 and 19 patients, respectively. Nine of the 125 patients died within 30 days of the operations, with an operative mortality of 7.2%. Eight of the nine deaths were due to liver failure in the cirrhotic patients who underwent resection of more than two segments of the liver. None of the jaundiced patients died postoperatively. The three-year actuarial survival rates of the patients with hepatocellular carcinoma, metastatic liver carcinoma, and carcinoma of the bifurcation of the hepatic ducts were 31%, 56%, and 21% respectively.

Adolescent↗
PubMed1984

The role of surface charge in ionic germination of Clostridium perfringens spores.

The surface charge against pH behaviour of spores of Clostridium perfringens type A was determined using a colloid titration method in the pH range 4-9. The native spores as well as various ionic forms of the spores loaded with divalent cations were found to be negatively charged. A positive colloid, MGCh, inhibited the ionic germination of the spores and this inhibition was highly dependent on pH. However, another positive colloid, GCh, did not inhibit the germination. Chemical modification of carboxyl groups on the spore surface by use of a water-soluble carbodiimide with two nucleophiles, glycine ethyl ester and taurine, caused spores not only to have little or no colloidal charge but also to lose the ability to germinate. The modification of carboxyl groups in the spore coat protein also resulted in elimination of, or marked reduction in its negative charge. These results suggest that carboxyl groups in the spore coat protein are the major negatively charged species on the spore surface. The role of surface charge in the ionic germination of the spores is discussed.

Amino Acids↗
PubMed1983

The majority of cDNA clones with strong positive signals for the interferon-induction-specific sequences resemble mitochondrial ribosomal RNA genes.

A complementary DNA library prepared from the 12S polyadenylated RNAs extracted from interferon-induced KG-1 cells, a human myeloblast cell line, was screened for the presence of induction-specific sequences. Clones that exhibited strong positive signals were separated by hybridization criteria into nine classes. Clones from classes I through IV consisted of about 78% of the total and unexpectedly were found to resemble human mitochondrial ribosomal RNA genes.

Base Sequence↗
PubMed1983

Carcinoma of the bifurcation of the hepatic ducts.

Thirty-one patients with carcinoma of the bifurcation of the hepatic ducts were treated during a period of ten years. Sixteen of the 31 patients underwent resection. Left, right, and extended right lobectomy with the resection of the bilateral hepatic ducts, common hepatic and bile ducts were performed on 11, 1, and 3 patients, respectively. In a cirrhotic patient, resection of the left medial segment and bile ducts was carried out. The biliary tract was reconstructed using hepaticojejunostomy or hepatojejunostomy. Four of the 16 patients are still alive for six months, 1 1/2 years, one year and 11 months, and two years and ten months, respectively. The remaining 12 patients died of recurrence at periods ranging from six months to three years and eight months. The treatment is now focused on increasing long-term survival.

Adenocarcinoma↗
PubMed1983

Presence of mitochondrial-DNA-like sequences in the human nuclear DNA.

Two lambda phage clones carrying contiguous human nuclear DNA sequences with extensive homology to non-contiguous human mitochondrial 16S ribosomal RNA sequences were isolated from a human gene library. The one clone carried mitochondrial-DNA(mtDNA)-like sequences flanked with two kinds of repetitive nuclear DNA sequences and the other carried mtDNA-like sequences, between unique nuclear DNA sequences and repetitive DNA sequences of Alu-family. These results demonstrate that mtDNA-like sequences are present in human nuclear DNA.

Base Sequence↗
PubMed1983

Mechanism of chemical manipulation of the heat resistance of Clostridium perfringens spores.

The mechanism of chemical manipulation of the heat resistance of Clostridium perfringens type A spores was studied. Spores were converted to various ionic forms to base-exchange technique and these spores were heated at 95 degrees C. Of the four ionic forms, i.e. Ca2+, Na+, H+ and native, only hydrogen spores appeared to have been rapidly inactivated at this temperature, when survivors were enumerated on the ordinary plating medium. However, the recovery of the survivors was improved when the plating medium was supplemented with lysozyme, and more dramatically when the heated spores were pretreated with alkali followed by plating in the medium containing lysozyme. In contrast to crucial damage to germination, in particular to spore lytic enzyme, no appreciable amount of DPA was released from the heat-damaged H-spores. These results suggest that a germination system is involved in the thermal inactivation of the ionic forms of spores, and that exchangeable cation load plays a role in protection from thermal damage of the germination system within the spore. An enhancement of thermal stability of spore lytic enzyme in the presence of a high concentration of NaCl was consistent with the hypothesis.

Calcium↗
PubMed1983

[The rationale of treatment after hepatectomy for primary cancer of the liver].

During a period of ten years ranging from January 1973 to February 1983, a total of 51 patients with primary cancer of the liver underwent hepatic resection at the Keio University Hospital. Thirty five of 51 patients were cirrhotic and two were jaundiced. Six cirrhotic patients died of liver failure within one month following hepatic resection. In order to minimize the postoperative death, it is mandatory to maintain the integrity of circulatory dynamics and microcirculation. Monitoring of circulatory dynamics with the use of Swan-Ganz catheter is very useful for managing the patients with massive transfusion, copious production of ascites and adult respiratory distress syndrome and is indispensable for hepatic resection using vascular exclusion technique. Disseminated intravascular coagulation occurs frequently after hepatic resection. It will cause hepatic failure due to microthrombi, unless prompt treatment is instituted. Score count was designed to facilitate diagnosis using platelet count, fibrinogen level, quantity of fibrin degradation product and protamine sulfate test as parameters. It is difficult to determine the optimal dose of heparin because of decreased antithrombin III and metabolism in the liver due to loss of hepatic parenchyma. Gabexate mesilate (FOY) is very effective and safe agent, since it works without antithrombin III.

Carcinoma, Hepatocellular↗
PubMed1982

Regional distribution of lead, zinc, iron and copper in suckling and adult rat brains.

The flameless atomic absorption method was applied to reveal regional differences in heavy metals between suckling and adult rat brains. The lead concentrations in the suckling brains were considerably different from those in the adult rats. The levels of lead concentration in the cerebrum and cerebellum of the normal suckling rats were 3-4 times higher than those of adult rats. Iron concentrations in the cerebrum of the suckling brains were approximately half those in the adult brains. Zinc and copper concentrations in medulla from the suckling rats were higher than those in the same region from the adult rats.

Aging↗