PubMed Health⌕ Search

Biomedical subjects

T Tsurumi

Publications and source records attributed to T Tsurumi.

At least 19 recordsLinked to original sources
PubMed1995

The US3 protein kinase of herpes simplex virus type 2 is associated with phosphorylation of the UL12 alkaline nuclease in vitro.

Herpes simplex virus type 2 (HSV-2) gene US3 encodes a serine-threonine protein kinase. We previously described the isolation of a US3-inactivated mutant which is able to replicate in Vero cells but not in murine macrophages. To learn more about the biological role of the US3 protein kinase, we have sought to identify the target proteins of the enzyme. Studies of in vitro phosphorylation with extracts of infected cells demonstrate that the US3 protein kinase is involved in phosphorylation of the UL12 alkaline nuclease in vitro, suggesting that the nuclease is a possible target of the protein kinase.

Animals↗
PubMed1992

Relationship between tumor DNA ploidy and regional lymph node changes in lung cancer.

Seventy-four patients with lung cancer, resected consecutively from April 1989 to August 1990, were divided into (1) 21 with diploid tumors having a single G0/G1 peak and a coefficient of variation (CV) of 4.9 or less, (2) 18 with peridiploid tumors having a single G0/G1 peak and a CV at 5.0 or more, and (3) 35 with aneuploid tumors having multiple G0/G1 peaks. Aneuploid tumors had higher frequencies of lymphatic invasion and metastasis to the mediastinal lymph nodes. To evaluate the relationship between ploidy tumor status and immunologic competence of the regional lymph nodes, histologic findings and the proportion of killer T-lymphocytes were examined in the dissected lymph nodes. Aneuploid tumors had significantly lower proportions of paracortical hyperplasia and killer T-lymphocytes than did diploid and peridiploid ones in the nonmetastatic lymph nodes of N0 and N1 disease. These findings suggest the possibility that a decline in the antitumor competence of these lymph nodes could cause metastasis to the nodes. The recurrence rates were 19% in diploid, 33% in peridiploid, and 54% in aneuploid tumors, and the 2-year survival rates were 87%, 78%, and 44%, respectively. Peridiploid tumors showed intermediate values between diploid and aneuploid in terms of immunologic competence, recurrence rate, and survival. They were assumed to have a different proportion of aneuploid cells than the other two.

Aged↗
PubMed1992

Selective inhibition of the 3'-to-5' exonuclease activity associated with Epstein-Barr virus DNA polymerase by ribonucleoside 5'-monophosphates.

Epstein-Barr virus (EBV) DNA polymerase possesses a proofreading 3'-to-5' exonuclease activity (Tsurumi, T. (1991) Virology 182, 376-381). The 3'-to-5' exonuclease activity can be selectively inhibited by ribonucleoside 5'-monophosphates, while no inhibition of the DNA polymerase activity can be observed even when the template/primer concentrations are rate-limiting. Deoxynucleoside monophosphates except 5'dGMP have almost no effect on the exonuclease activity. Of the four ribonucleoside monophosphates, 5'GMP is the most potent (62% inhibition at 5 mM). The kinetic study shows that 5'-GMP inhibits the exonuclease activity competitively with respect to DNA template/primer. During DNA polymerization process the EBV DNA polymerase catalyzes the DNA-dependent conversion of complementary deoxynucleoside triphosphate to monophosphate form. With poly(dT).oligo(rA) as a template primer, selective inhibition of the exonuclease activity by 5'-GMP results in a decrease in the amount of free dAMP generated which is complementary to the template DNA, suggesting the functional relationship between the editing exonuclease activity and the chain elongation activity of the EBV DNA polymerase molecule.

Escherichia coli↗
PubMed1992

[Operation of pleural dissemination of thymoma].

Nine patients underwent operation for pleural dissemination of thymoma and received radiotherapy postoperatively. In 5 patients dissemination was resected along with the invasive thymoma at the initial operation. In 6 patients resection of a part of the diaphragm was needed. In 4 patients recurrent dissemination of thymoma appeared in the phrenico-costal sinus, where not only the location of dissemination but also postoperative radiotherapy had not been performed properly at the time of the previous operation. Seven are alive 2 months to 7 years 10 months after the first operation for dissemination. Two died respectively 7 years and 3 years 5 months after the first operation for dissemination.

Adult↗
PubMed1991

Primer terminus recognition and highly processive replication by Epstein-Barr virus DNA polymerase.

The Epstein-Barr virus (EBV) DNA polymerase is essential for viral DNA replication in the lytic phase of the EBV life cycle. It efficiently extends RNA primers on the template DNA, suggesting the possible involvement of the EBV DNA polymerase in synthesizing Okazaki fragments from RNA primers on the lagging strand template. Competition experiments revealed that the EBV DNA polymerase had significantly higher affinity for primer termini hybridized to the template DNA than for the single-stranded DNA template or the single-stranded primer itself. ATP was not required either for primer terminus recognition or for sustainment of polymerization. The stimulation of the enzyme by (NH4)2SO4 was dependent on the template/primers utilized. These observations suggest that the primary and secondary structure of the template/primers are important factors for primer terminus recognition by the EBV DNA polymerase. The enzyme elongated synthetic RNA primer annealed to circular single-stranded M13 DNA coated with Escherichia coli single-stranded DNA-binding protein without dissociation. The processivity of the EBV DNA polymerase was strikingly high (greater than 7200 nucleotides) and the rate of polymerization was 12 nucleotides/s per polymerase molecule. The high processing capacity is a desirable feature in the synthesis of multiple copies of the EBV genome in rolling-circle DNA replication.

Adenosine Triphosphate↗
PubMed1991

Prognostic implications of DNA histogram, DNA content, and histologic changes of regional lymph nodes in patients with lung cancer.

Forty-six cases of resected lung cancer, including 20 cases at Stages I and II and 26 cases at Stage III (N2), were subdivided into two groups: a good prognosis group with a longer survival period and a poor prognosis group in which the patients died earlier of the cancer. From paraffin-embedded lymph node tissues of these patients, the authors examined DNA histogram pattern and DNA content, using flow cytometry, and histologic hyperplasia of germinal center and paracortical area; they also evaluated their correlation with the prognosis. In the good prognosis group at Stages I and II, paracortical hyperplasia (PH) of the lymph nodes was observed significantly more frequently. In the good prognosis group at Stage III, the incidence of PH, G2M phase in the DNA histograms, and DNA content were all significantly higher. DNA content was positively correlated with the grade of PH.

Adenocarcinoma↗
PubMed1991

Characterization of 3'-to 5'-exonuclease activity associated with Epstein-Barr virus DNA polymerase.

Epstein-Barr virus (EBV) DNA polymerase mediates viral DNA replication during the lytic phase of the EB virus life cycle. In order to characterize its enzymatic activities EBV DNA polymerase was purified more than 1200-fold from chemically induced B95-8 cells. One polypeptide with molecular weight of 110,000 corresponded to the predicted EBV DNA polymerase, whereas the other polypeptides did not. A 3'-to-5' exonuclease activity was copurified with the EBV DNA polymerase through the course of the purification. Unlike HSV DNA DNA polymerase, 5'-to-3' exonuclease activity was not associated with the EBV DNA polymerase on the final step chromatography of single-stranded DNA agarose column. The associated 3'-to-5' exonuclease activity was stimulated by ammonium sulfate like the polymerase activity. It exhibited DNA-dependent nucleotide turnover activity and preferentially excised a terminal mismatched nucleotide on hybridized polynucleotides compared to the correctly paired substrate, indicating that the 3'-to-5' exonuclease may play a role in proofreading in the polymerization process.

Ammonium Sulfate↗
PubMed1990

Release of RNA polymerase from vero cell mitochondria after herpes simplex virus type 1 infection.

Infection of Vero cells with herpes simplex virus type 1 results in the appearance in soluble extracts of a DNA primase activity. The partially purified enzyme, Mr, approximately 100,000, is identical in resistance to alpha-amanitin, pH profile, Mg2+ dependence, salt sensitivity, and KmATP to the catalytic core of Vero cell mitochondrial RNA polymerase. Moreover, the products synthesized are those expected of an RNA polymerase rather than a DNA primase. Inasmuch as the enzyme is not present in soluble extracts of uninfected Vero cells, we presume that the specific appearance of RNA polymerase in extracts of herpesvirus-infected cells results from infection-induced disruption of the mitochondrial membrane, followed by release of the enzyme into the cytosol.

Animals↗
PubMed1990

[Surgical treatment of bullous emphysema using Gore-Tex sheet].

Surgical treatment for bullous emphysema using Gore-Tex sheet and mechanical stapler is reported. The techniques were followed in a Juetnner's report: Small cut is made at the center of a 10 cm square of a Gore-Tex sheet, through which the area of bullous lung planned for resection is tented out with a lung forceps. A stapling instrument charged with a 4.8 mm clips is placed over the sheet around the suture line, and closed over both sheet and lung parenchyma. The excess sheet is removed after resection of the bullous lung. Five cases of bullous emphysema with a history of pneumothorax were successfully treated by the above method. Air leakage disappeared on the first postoperative day at latest. We assume Gore-Tex sheet, although a non-absorbable material, is in use as well as polydioxanone ribbon for prevention of air leakage in surgical cases of bullous emphysema.

Adult↗
PubMed1989

Herpes simplex virus 1 helicase-primase: a complex of three herpes-encoded gene products.

In an earlier report, we described a DNA helicase that is specifically induced upon infection of Vero cells with herpes simplex virus 1. We have purified this enzyme to near homogeneity and found it to consist of three polypeptides with molecular weights of 120,000, 97,000, and 70,000. Immunochemical analysis has shown these polypeptides to be the products of three of the genes UL52, UL5, and UL8 that are required for replication of a plasmid containing a herpes simplex 1 origin (oriS). In addition to helicase activity, the enzyme contains a tightly associated DNA primase. Thus, the three-subunit enzyme is a helicase-primase complex that may prime lagging-strand synthesis as it unwinds DNA at the viral replication fork.

Adenosine Triphosphatases↗
PubMed1989

A novel method for removal of human immunodeficiency virus: filtration with porous polymeric membranes.

We propose a new method to rid solutions of a virus by using a novel regenerated multilayered structured cellulose membrane (BMM). When the filtrate of human immunodeficiency virus (HIV) preparation was obtained through BMM it showed no infectivity. Electron microscopic observation revealed that HIV was completely caught by the multilayers of the BMM. Conveniently, BMM was seldomly found to adsorb protein molecules and also to have a high filtration rate. These characteristics may have a use in the removal of other variously sized pathogenic agents from plasma.

Cells, Cultured↗
PubMed1989

[A case of pulmonary infarction secondary to subacute bacterial endocarditis with subpulmonary VSD].

A case of pulmonary infarction secondary to subacute bacterial endocarditis of pulmonary valve which is associated with subpulmonary VSD is presented. The jet stream of blood through the subpulmonary VSD made damage to the pulmonary valve, which may be one of the reasons why subacute bacterial endocarditis was associated with the subpulmonary VSD. Echocardiography of the right-sided valves will be very useful in order to detect the pulmonary valve endocarditis in congenital heart disease presenting with fever.

Adult↗
PubMed1988

Interactions between UFT and anticoagulants in lung cancer patients.

In order to study the interactions between UFT and anticoagulants, the plasma and tissue concentrations of 5-FU, uracil and FT-207 were examined in patients with lung cancer. Higher plasma concentrations of 5-FU and uracil were observed in the patients who were given warfarin and ticlopidine beforehand, whereas the concentrations of FT-207 were almost the same in the patients who were given anticoagulants as in those who were not. This may be interpreted as an inhibition of dihydrouracil dehydrogenase, the common metabolizing enzyme of 5-FU and uracil, by anticoagulants. With regard to the tissue concentrations, higher levels of 5-FU and uracil in the tumor and lymph nodes were obtained after anticoagulants were given beforehand. Concentrations of FT-207 in these tissues, however, were almost the same in the patients who were given anticoagulants as in those who were not. We thus concluded that an increase of 5-FU in tumor cells and lymph nodes can be achieved after elevating the plasma concentrations of ordinary oral doses of UFT by using anticoagulation therapy beforehand.

Aged↗
PubMed1987

Mechanism of inhibition of herpes simplex virus replication by delta 7-prostaglandin A1 and delta 12-prostaglandin J2.

We studied the effect of prostaglandins (PGs) A1, delta 7-A1, A2, D2, E1, E2, F2 alpha, J2 and delta 12-J2 on the replication of herpes simplex virus type 2 (HSV-2). Of nine PGs we tested, delta 7-PGA1 was found to have the most potent inhibitory effect; 50% inhibitory dose (ID50) was 0.35 microgram/ml in the plaque reduction assays and HSV-2 induced protein synthesis was strongly suppressed at 0.5 microgram/ml whereas at this dose, the protein synthesis of uninfected cells was not inhibited. Dot blot hybridization analysis revealed that delta 7-PGA1 and delta 12-PGJ2 inhibited the primary transcription of HSV-2. Thus we suggest that those PGs are primarily active at the level of mRNA synthesis.

Cell Transformation, Viral↗
PubMed1987

Nucleotide sequence of the DNA polymerase gene of herpes simplex virus type 2 and comparison with the type 1 counterpart.

The complete nucleotide sequence of the DNA polymerase gene of herpes simplex virus (HSV) type 2 strain 186 has been determined. The gene included a 3720-bp major open reading frame capable of encoding 1240 amino acids. The predicted primary translation product had an Mr of 137,354, which was slightly larger than its HSV-1 counterpart. A comparison of the predicted functional amino acid sequences of the HSV-1 and HSV-2 DNA polymerases revealed 95.5% overall amino acid homology, the value of which was the highest among those of the other known polypeptides encoded by HSV-1 and HSV-2. The functional amino acid changes were spread in the N-terminal one-third of the protein, whereas the C-terminal two-third was almost identical between the two types except a particular hydrophilic region. A highly conserved sequence of 6 aa, YGDTDS, which has been observed in DNA polymerases of HSV-1, Epstein-Barr virus, adenovirus, and vaccinia virus, was also present at positions 889 to 894 in the C-terminal region of HSV-2 DNA polymerase.

Amino Acid Sequence↗
PubMed1987

Effects of the epipodophyllotoxin VP-16-213 on herpes simplex virus type 2 replication.

It has been recently shown that VP-16-213, a semi-synthetic derivative of podophyllotoxin, inhibits the function of mammalian DNA topoisomerase II. In the present study, we examined the effects of VP-16-213 on the replication of herpes simplex virus type 2 (HSV-2). The compound did not inhibit the synthesis of early viral polypeptides at concentrations at which viral DNA synthesis was strongly suppressed, but induced double-strand breaks in newly synthesized HSV DNA. Electron microscopic examination of treated cells revealed the presence of a number of capsids with empty or partial cores. The level of topoisomerase II activity remained unaltered after infection, and all attempts to isolate VP-16-213-resistant mutants of HSV-2 have failed in spite of extensive efforts. It is suggested therefore that the mode of action of VP-16-213 may be inhibition of viral DNA synthesis by impairing the function of host cell topoisomerase II.

Animals↗
PubMed1987

A single-base change within the DNA polymerase locus of herpes simplex virus type 2 can confer resistance to aphidicolin.

An aphidicolin-resistant (Aphr) mutant of herpes simplex virus (HSV) type 2 strain 186 previously has been shown to induce an altered viral DNA polymerase that is more resistant to aphidicolin and more sensitive to phosphonoacetic acid (PAA) than is wild-type DNA polymerase. In this study the mutation responsible for the aphidicolin-resistant phenotype was physically mapped by marker transfer experiments. The physical map limits for the Aphr mutation were contained in a 1.1-kilobase pair region within the HSV DNA polymerase locus. The 1.1-kilobase-pair fragment of the Aphr mutant also conferred hypersensitivity to PAA, and DNA sequence analysis revealed an AT to GC transition within this fragment of the Aphr mutant. Analysis of the three potential open reading frames within the 1,147-base-pair fragment and comparison with the amino acid sequence of DNA polymerase of HSV type 1 indicated that the Aphr mutant polymerase had an amino acid substitution from a tyrosine to a histidine in the well-conserved region of the DNA polymerase. These results indicate that this single amino acid change can confer altered sensitivity to aphidicolin and PAA and suggest that this region may form a domain that contains the binding sites for substrates, PPi, and aphidicolin.

Animals↗