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Biomedical subjects

K Shimada

Publications and source records attributed to K Shimada.

At least 1,621 records · Page 90Linked to original sources
PubMed1975

Induction of phage production in the lysogenic Escherichia coli by hydroxyurea.

1) Hydroxyurea, a reversible DNA synthesis inhibitor, was used to study the mechanism of prophage lambda induction in Escherichia coli K12. Induction of prophage was judged on two criteria: increase of phage-producing cells and loss of colony-forming ability of the cells. 2) Hydroxyurea induced an increase of phage-producing cells only in lysogenic strains known to be inducible with ultraviolet irradiation for prophage development and not in strains such as E. coli K12 (lambdaind-) or E. coli K12 recA (lambda+). 3) When protein synthesis was inhibited, hydroxyurea did not increase phage-producing cells of lysogenic strains; it showed a bacteriocidal effect on lysogenic recA+ strains, but not on nonlysogenic strains. 4) The sensitivity of E. coli K12 recA to hydroxyurea was independent of whether or not the cells were lysogenic. 5) From the results it is suggested that certain steps leading to loss of colony-forming ability (i.e. prophage induction) do not require de novo protein synthesis but require the presence of the host recA+ gene.

Bacterial Proteins↗
PubMed1975

Determination of serum C9 level by immunodiffusion. Elevation in patients with infectious or allergic skin diseases.

The measurement of the ninth component of complement (C9) in human serum can be easily carried out by the Mancini method using antiserum raised against purified C9. The average C9 level in 29 healthy adults was 44.5 plus or minus 10.6 mug/ml. The serum C9 level was often elevated in patients with infectious or allergic skin diseases. The C9 level remained normal in most patients with collagen diseases. The availability of the monospecific antiserum has permitted identifying C9 in human serum as alpha2-globulin.

Adult↗
PubMed1975

Local antibody formation within the eye: a study of immunoglobulin class and antibody specificity.

Primary immunogenic uveitis was induced in the rabbit eye with a single injection of antigen into the vitreous, and secondary booster uveitis responses were induced two months later by intravenous administration of the same antigen. The distribution of immunoglobulin classes and the specificity of the antibodies produced were assessed early and late in the primary response and early and late in the secondary response, and were compared with the analogous responses in the spleen and regional lymph nodes. At each of these stages of intraocular antibody response, IgG formation was higher and IgM formation lower than that seen in organized lymphoid tissues, while the proportion of IgA-forming cells was similar to the low levels usually found in the spleen. A significant proportion of IgA-forming cells was found in the perilimbal conjunctiva, and even greater levels in the lacrimal glands. At each stage of the response, the proportion of immunoglobulin-forming cells making antibody specific for the inciting ovalbumin antigen was surprisingly low, reaching only seven per cent during the late primary reaction and 18 per cent during the late secondary reaction.

Animals↗
PubMed1975

Long-term intermittent adjuvant chemotherapy for primary, resected lung cancer.

Adjuvant chemotherapy for lung cancer has previously been unsuccessful in improving the results of pulmonary resections. During a 12 year period, we tested long-term intermittent chemotherapy (LTIC) with mitomycin C and chromomycin A3 adjuvant to resections. LTIC was begun before the operations and the first course was completed postoperatively. Additional courses of 4 weeks each were scheduled at 3 month intervals during the first postoperative year and at 6 month intervals during the next 2 years. LTIC was defined as three or more full courses, and short-term chemotherapy (STC) was defined as a single course of adjuvant treatment. Resections for cancer in 425 patients over a 22 year period included 117 operations during a 10 year control period in which LTIC was not used and 308 during the LTIC test period. Results from adjuvant LTIC in 85 patients were compared with lesser adjuvant chemotherapy in 155 synchronously treated patients who included 77 STC recipients. Further comparison was made between LTIC and asynchronously treated, comparable control subjects. Although there were side effects and occasional deaths from chemotherapy, they did not alter the operative mortality rate. The over-all 5 year survival rate of the adjuvant LTIC patients was 50.9 per cent, as compared to 22.6 per cent in the asynchronous control subjects (p less than 0.01). For patients who were given LTIC adjuvant to palliative resections the 5 year survival rate was 35.6 per cent, as compared to 4.3 per cent for STC patients or 5.2 per cent for asychronous control subjects (p less than 0.01). Strikingly promising results were obtained from adjuvant LTIC in 10 of 33 patients with undifferentiated cancers. We conclude that LTIC prolonged life among lung cancer patients who were not cured by resection alone. Dual-agent LTIC is safe, apparently beneficial, and worthy of further clinical trials in a research setting.

Adenocarcinoma↗
PubMed1975

Cinemicrographic analysis of the movement of flagellated bacteria. I. The ratio of the propulsive velocity to the frequency of bodily rotation.

On the basis of the hydrodynamic model that the propulsion of flagellated bacteria in a fluid is a consequence of the propagation of helical waves along the length of flagella or flagellar bundles, it is predicted that propulsion must be accompanied by a rotation of bacterial body about the direction of translation (Chwang and Wu, 1971), and that propulsive velocity u is directly proportional to the frequency of bodily rotation fB, the proportional constant being a complicated function of various parameters describing the sizes and shapes of body and flagella. In this study we have measured not only u but also fB by cinemicrography or sometimes by dual cinemicrography, using a mono- trichously flagellated Pseudomonas strain and a multitrichously flagellated Salmonella strain, and calculated the ratio u/fB. Though the values of u/fB thus determined for a number of bacteria of each strain scattered in a wide range, average values of u/fB were likely to be independent of u, in support of the theoretical prediction. Moreover, in Pseudomonas as well as in Salmonella, it was found that the experimental values of u/fB were in semiquantitative agreement with theoretical values expected from the hydrodynamic model for appropriate values of the geometrical parameters. Taking into account these results, it was concluded that the validity of this model has been supported experimentally.

Cell Movement↗
PubMed1975

Chimeric analysis of hemopoietic cells after cross-sex parabiosis.

Anemia or polycythemia was induced in male rats. These males were conjugated with healthy, untreated female litter mates by FANG'S method of aortic parabiosis that resulted in complete cross circulation of blood between the two animals. The sex chromosomes of cells in erythropoiesis in various hemopoietic organs were examined in the treated male animals. The anemic parabionts indicated sharp increases in chimerical rates with erythroid marrows being evident. Polycythemic parabionts indicated marked decreases in chimerical rates with evidence of myeloid marrows. These findings suggested that the so-called stem cells in peripheral blood of the female parabiont migrated to the bone marrow of the male partner and that these migrating cells differentiated to erythroblast. The possible relationships between erythropoiesis and other cell proliferations in the hemopoietic organs are discussed.

Anemia↗