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Biomedical subjects

H Uchida

Publications and source records attributed to H Uchida.

At least 505 records · Page 28Linked to original sources
PubMed1987

[4,4'-(Z)-dehydrophenylalanine]gramicidin S with stabilized bioactive conformation and strong antimicrobial activity.

Dehydrophenylalanine (delta Phe) was incorporated into an antibiotic peptide gramicidin S (GS) in place of D-Phe4,4' to prepare an unsaturated analog. Conformational analysis with 1H-NMR indicated that the unsaturated analog has much the same backbone conformation as that of natural gramicidin S as shown by NOE experiments. Studies on temperature dependences and on the chemical shift differences showed that the hydrogen bonds between Val-NH and Leu-CO in the unsaturated analog are strengthened by the incorporation of delta Phe4,4'. This resulted in the reinforcement of the beta-sheet structure which is the most important structural element for GS bioactivity. [delta Phe4,4']gramicidin S exhibited indeed very strong antimicrobial activities against Gram-positive bacteria as well as the natural peptide.

Circular Dichroism↗
PubMed1987

Oncostatic and immunomodulatory effects of a glycoprotein fraction from water extract of abalone, Haliotis discus hannai.

The liquid from heat-treatment of an abalone, Haliotis discus hannai, which is normally discarded as waste, was found to contain a new glycoprotein antineoplastic agent. A fraction of the liquid obtained from chromatography that was 22% carbohydrate and 44% protein was injected locally or systemically into ICR mice or BALB/c mice inoculated s.c. with allogeneic sarcoma 180 or syngeneic Meth-A fibrosarcoma, and growth of the tumors was strongly inhibited. There was an optimum dose range for the inhibition of the growth of sarcoma 180, and optimum timing. The fraction did not have antitumor activity in T cell-deficient nude mice (CD-1 nu/nu or BALB/c nu/nu mice), and administration of carrageenan in vivo decreased its activity in ICR mice. This fraction activated the cytostatic activity of peritoneal and alveolar macrophages in vivo. These results suggest that the antitumor activity is not due to a direct toxic effect but to stimulation of a host-mediated response.

Adjuvants, Immunologic↗
PubMed1987

The Escherichia coli dnaJ mutation affects biosynthesis of specific proteins, including those of the lac operon.

Temperature-sensitive dnaJ mutants of Escherichia coli showed a thermosensitive defect in the synthesis of beta-galactosidase. Synthesis of the lac mRNA was greatly reduced at the restrictive temperature. The mutants were also conditionally defective in the synthesis of a subset of membrane proteins such as succinate dehydrogenase, whereas the synthesis of anthranilate synthetase, encoded by trpED, as well as that of most cellular proteins, was unaffected at the restrictive temperature. The defect was specific for the dnaJ mutants among several dna mutants which are known to be involved in the initiation of DNA synthesis: dnaK, dnaA, and dnaB mutants synthesized each of these proteins normally even at the restrictive temperature. At the restrictive temperature, growth of the dnaJ mutants was arrested at a specific stage of the cell cycle.

Anthranilate Synthase↗
PubMed1987

Myocardial ultrastructure in Kearns-Sayre syndrome.

Myocardial ultrastructural changes are described in a twenty-five-year-old female with typical Kearns-Sayre syndrome. The electrocardiogram revealed complete atrioventricular block with an occasional torsades de pointes type of ventricular tachycardia. His bundle recording demonstrated HV block with normal AH interval. An endomyocardial biopsy showed "ragged-red fibers" by the modified Gomori trichrome stain, and on electron microscopy there were increased numbers of morphologically abnormal mitochondria: ie, gian mitochondria, a whorled pattern of the cristae, and electron-dense substances, and paracrystalline inclusions in the mitochondria. The patient has been well since pacemaker implantation, but she may develop a clinically overt cardiomyopathy due to progression of myocardial involvement.

Adult↗