Biomedical subjects
Publications and source records attributed to T Ohtomo.
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Explore the source record for details and available documents.
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Sub-MIC range of 8 kinds of beta-lactam antibiotics and 3 kinds of aminoglycoside antibiotics against strain of Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa isolated from clinical source were determined by nephlometic method, and following results were obtained. When 10 strains of S. aureus tested to ampicillin (ABPC), hetacillin (IPABPC), mecillinam (MPC), cephalexin (CEX), cefotaxime (CTX), latamoxef (LMOX), cefatrizine (CFT), cephapirin (CEPR), gentamicin (GM), dibekacin (DKB) and amikacin (AMK), ratio of MIC to MAC were 36.8, 53.6, 156.8, 29.6, 61.6, 34.4, 50.0, 111.2, 9.2, 20.0 and 13.6, respectively. When 10 strains of K. pneumoniae tested to MPC, CEX, CTX, LMOX, CFT, CEPR, GM, DKB and AMK, ratio of MIC to MAC were 409.6, 10.4, 34.4, 123.2, 39.2, 167.2, 5.2, 5.6 and 13.2, respectively. When 10 strains of P. aeruginosa tested against CTX, LMOX, GM, DKB and AMK, ratio of MIC to MAC were 16.8, 38.4, 6.8, 3.2 and 10.4, respectively.
Remarkable alteration was shown in capsular type antigen production in encapsulated strains of Staphylococcus aureus stored by lyophilization for 10 years. This alteration was further elucidated by antibody production in rabbits immunized with the altered strain and by absorbing the antibodies with representative capsular type strains.
With the addition to a soft-agar medium of rabbit anti-flagella serum inhibiting mobility, strain SM-1 of Serratia marcescens produced single colonies. Strain SM-1 and its variants A and B exhibited three kinds of colonial form. The parent strain showing extra large round-type growth in the medium had the highest cell volume index and mouse virulence, and a large capsule was seen on electron microscopy. An intermediate cell volume index and a remarkably lower mouse virulence were observed with variant A, which exhibited diffuse-type growth in the medium, although no definite extracellular feature was shown. The variant B, showing compact-type growth in the medium, represented the lowest cell volume index, mouse avirulence and was not encapsulated. Mouse virulence of the parent strain was assumed to be related to encapsulation which protects against phagocytosis.
In a previous paper, we showed that bile acid derivatives inhibit capsule formation as well as taurine biosynthesis in a taurine+ (Tau+) encapsulated strain of Staphylococcus aureus. In the present study, binding of [14C]cholic acid [( 14C]CA) and [14C]taurocholic acid [( 14C]TA) to the staphylococcal polysaccharide antigen (SPA) of the capsular fraction was examined. The bile acids were found to bind with SPA via taurine of the Tau+ cells. [14C]CA bound with the SPA fraction of the Tau+ strain within 10-30 min, whereas 60-120 min was required in the binding of [14C]TA. Various bile acids competed with cholic acid binding to Tau+ cells which was shown by the inhibition of binding with cholic acid or taurocholic acid but not with glycholic acid. Binding of bile acid derivatives to a Tau- encapsulated mutant or to capsular material from this mutant was not observed.
We developed a new method for the quantitative evaluation of 201T1 exercise myocardial scintigraphy. Final diagnostic images obtained by this method were displayed on the two-dimensional views of the left ventricular wall. Five projection images obtained 10 min and 3 hrs after exercise were recorded respectively in the magnetic disk. Each image was divided into seven fan-shaped segments utilizing the apical image as the reference which was placed in the middle. The corrected uptake indices were examined in 20 normal controls and served as the normal data. Each segment was then judged to be intact or ischemic or infarcted by matching the segmental uptakes of the images given 10 min and 3 hrs after exercise. The results were displayed on the computer-assisted color monitor as the two-dimensional view of the left ventricular wall. In order to evaluate its diagnostic usefulness in coronary artery disease, comparative coronary angiography was performed in 25 patients. The present technique proved to have high sensitivity and specificity both in left anterior descending artery and right coronary artery diseases (88 and 78%, respectively in the former and 83 and 89%, respectively in the latter).
An alkali-stable polysaccharide (called compact-colony forming active substance; substance 1) obtained from the cell surface of a strain of Staphylococcus epidermidis caused gel formation of human fibrinogen, with no release of fibrinopeptides. Substance 1 possessed neither esterase nor caseinolytic activities; no inhibition of gel formation was shown by dinitrofluorophosphate. Heparin and galactose prevented gel formation of fibrinogen with substance 1. With the addition of early- and late-fibrinogen or fibrin degradation products into the fibrinogen sample, no prolongation of the gel formation time was observed. This substance is, therefore, assumed to nonenzymatically induce gel formation with fibrinogen, a process resembling paracoagulation.
Using 200 fresh isolates of Staphylococcus epidermidis, the relationship between type of growth in soft-agar medium and respiration, dehydrogenase activity and biotype was investigated. When strains of S. epidermidis were cultured in Brain Heart Infusion medium containing 0.15% (w/v) agar, the following different growth types were observed: compact colonial morphology with growth throughout the medium (type A), or with growth only at the surface (type B); and diffuse colonial morphology with growth throughout the medium (type C), growth only at the surface (type D), or growth from the surface to the middle of the tube (type E). Five representative strains of each growth type were studied and different results for cytochrome pattern, oxygen consumption and relative activities of lactic dehydrogenase and succinic dehydrogenase were obtained with different growth types. However, there was no correlation between growth type and biotype.
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Various bile acids were added to cultures of encapsulated strains of Staphylococcus aureus growing in serum-soft agar medium of brain heart infusion broth. We examined effects of these compounds on cellular characteristics such as growth type, cell volume index, clumping factor reaction, slime yield, taurine content, and L-(--)-cysteic acid decarboxylase activity. Upon addition to the medium of either taurochenodeoxycholic acid, taurocholic acid (25 to 50 microgram/ml), or cholic acid (10 to 25 microgram/ml), the colonial morphology of taurine-positive cells (strain S-7) was altered from the diffuse to the compact type in serum-soft agar. Also, the titer of the clumping factor reaction increased, while the cell volume index and slime yield were markedly decreased. Tauro-bile acids, including taurocholic acid, taurochenodeoxycholic acid, taurodehydrocholic acid, and taurodeoxycholic acid (50 microgram/ml) inhibited the synthesis of taurine and resulted in decreased L-(--)-cysteic acid decarboxylase activity. Among all of the derivatives cholic acid itself was found to inhibit slime production and L-(--)-cysteic acid decarboxylase activity to the greatest extent. Glyco-bile acid derivatives and taurolicholic acid (50 to 100 microgram/ml) had no effect on L-(--)-cysteic acid decarboxylase activity. Compounds such as glycodeoxycholic acid (50 to 100 microgram/ml) had no effect upon any of the cellular characteristics tested. No effect was observed upon addition of any of these compounds to cultures of the taurine-negative strain (T-26-B). We did find a correlation between the inhibition of taurine biosynthesis and decreased slime production. Electron micrographs indicated that this encapsulated strain was converted to an unencapsulated state in the presence of bile acids.
The compact-colony-forming active substance (CCFAS) extracted from a Staphylococcus aureus strain was capable of killing mice only when Staph. aureus, Staph. epidermidis or Escherichia coli was injected i.v. before the injection of CCFAS. In the mice killed 30 min after treatment with heat-killed Staph. aureus and CCFAS, remarkable congestion of the lung and thrombus-like lesions in the kidney were observed. In the mice killed 6 h after injection with CCFAS and living Staph. aureus congestion and inflammatory-cell filtration were found in the liver, especially within the Glisson's capsule. However, when mice were killed 30 days after treatment with CCFAS and Staph. aureus, fibrin and hyalin thrombi were observed most frequently in the renal glomeruli but also in the liver and lung.
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Plasma was used from rat, mouse, guinea pig, rabbit, dog, cat, sheep, goat, monkey, horse, pig, cow, fox, mink, porpoise, deer, manatee, seal, elephant, raccoon, pigeon, macaw, and humans; clotting time and gel formation activities by the compact-colony forming active substance (CCFAS) extracted from a strain of Staphylococcus aureus and relative staphylococcal clumping factor reaction were determined. Experimental results showed that every plasma was clotted and gel formation of plasma was observed by the CCFAS, however, although it was shown by the other plasmas, no clumping-factor reaction was observed with plasma from guinea pig, goat, and elephant.
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Fresh isolates of 204 strains of Streptococcus haemolyticus, 75 strains of viridans group Streptococcus, and 45 strains of Streptococcus pneumoniae were studied for their clumping reactions with human plasma. The plasma and serum factors that clumped the streptococcal strains were compared with those that clumped a Staphylococcus aureus strain. One hundred eleven strains of S. haemolyticus, 10 strains of viridans group Streptococcus, and none of the strains of S. pneumoniae tested were clumped by human plasma. However, clumping activity was remarkably unstable after subculturing on plates containing Todd-Hewitt blood agar. The strain with the highest level of activity was clumped by fibrinogen and normal human serum. Results of tests of the clumping reactions of staphylococci and streptococci with human serum indicated that the serum factors responsible for those reactions may be identical.