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Biomedical subjects

T Naito

Publications and source records attributed to T Naito.

At least 325 records · Page 18Linked to original sources
PubMed1977

Cephalosporins. I. Cephaloglycin analogs with six-membered heterocycles in the C-3 side chain.

Cephaloglycin analogs with six-membered heterocycles in the C-3 side chain have been prepared by nucleophilic substitution of 7-aminocephalosporanic acid with appropriate azine thiols followed by 7-N-acylation with phenylglycine by the mixed anhydride method. Seventeen thiols of non-substituted or substituted pyridines, pyridazines, pyrimidines, pyrazines and triazines were used as the S-nucleophiles. In general, pyridazine thiols gave cephalosporins processing good antimicrobial activity against both gram-positive and gram-negative bacteria. Among them 6-hydroxypyridazine-3-thiol gave the most active compound of this series, BB-S 118 (1f), which was significantly more active than cephalexin and cephaloglycin in vitro against gram-positive and gram negative bacteria.

Animals↗
PubMed1977

Cephalosporins. II. 7-(O-Aminomethyl-phnylacetamido) cephalosporanic acids with six membered heterocycles in the C-3 side chain.

7-(o-Aminomethylphenylacetamido)cephalosporanic acids with six-membered heterocycles in the C-3 side chain were prepared by nucleophillic substitution of 7-ACA at the C-3 acetoxy group followed by N-acylation of the 7-amino group. The 7-side chain acid, o-aminomethylphenylacetic acid (5), was prepared by two new convenient routes, which involved Schmidt reaction of indanone (2) followed by cleavage of the lactam ring or reduction of o-cyanophenylacetic acid (10) starting from o-nitrotoluene. The antibacterial activity of the cephalosporins in this series depends on the heterocycle in the C-3 side chain. In general pyridazines gave cephalosporin derivatives possessing better activity than those with a pyridine or pyrimidine ring. The most active member of the new cephalosporins was 7-(o-aminomethylphenylacetamido)-3-(6-hydroxypyridazin-3-ylthilmethyl)-3-cephem-4-carboxylic acid (BB-S 150) (1g) which has in vitro antibacterial activity superior to cephalothin and cefazolin against both gram-negative and gram-positive organisms. The in vitro activity of BB-S 150 determined in mice was superior to cephalothin and comparable to cefazolin.

Animals↗
PubMed1977

Cephalosporins. III. 7-(O-Aminomethylphenylacetamido)cephalosporanic acids with bicyclic heteroaromatics in the C-3 side chain.

Bicyclic heteroaromatic thiols with a bridge-head nitrogen atom were used for nucleophilic substitution of 7-ACA at the C-3 acetoxy function followed by N-acylation of the 7-amino group with o-aminomethylphenylacetic acid to afford a series of new cephalosporins (24) with potent antibacterial activity against gram-positive and gram-negative organisms. The most active member of this series was 7-(o-aminomethylphenylacetamido)-3-(tetrazolo-[4,5-b]pyridazin-6-ylthiomethyl)-3-cephem-4-carboxylic acid (BB-S 226) (24e) with antibacterial activity superior activity superior to cephalothin and cefazolin.

Bacteria↗
PubMed1977

The relationship of cellular immunity to prognosis in acute leukemia.

Forty-five patients with acute leukemia were compared on cellular immunity measures versus prognosis. The patients were treated according a multicombination therapy protocol. The purified protein derivative (PPD) test and dinitrochlorobenzene (DNCB) test on admission indicated low positive percentages. In acute non-lymphocytic leukemia (ANLL) patients, the 50% survival durations were 11 months in the PPD positive group and 6 months in the PPD negative group. In acute lymphocytic leukemia (ALL) patients, the 50% survival durations were 21 months in the PPD positive group and 13 months in the PPD negative group. Peripheral lymphocyte blastogenesis by phytohemagglutinin (PHA) stimulation was examined at various clinical stages. The stimulation indices were generally low, and no correlation was found between the PHA test and clinical stages. These cellular immunity measures appeared to reflect one aspect of the clinical condition in acute leukemia patients, and further studies are needed for predicting prognosis.

Acute Disease↗
PubMed1977

[Agenesis of internal carotid artery associated with aneurysm of anterior communicating artery (author's transl)].

A case of agenesis of the left internal carotid artery with an aneurysm of the anterior communicating artery was reported in detail. The patient was a 48-year-old man who had an episode of subarachnoid hemorrhage about 10 years ago. This time left heminumbness and motor weakness of the left lower extremity occured and he was brought our hospital. Right common carotid angiography, left retrograde brachial serial angiography and aortography demonstrated an agenesis of the left internal carotid artery, an aneurysm of the anterior communicating artery, tortuous megadolic hobasilar artery and anomalies on the circle of Willis such as absence of supra optic portion of the right anterior cerebral artery, and large left posterior communicating artery. We confirmed latter findings by operation. After successful neck clipping of the aneurysm, his clinical findings were remarkably improved.

Carotid Artery, Internal↗
PubMed1976

Chemical modification of sorbistin. I. N-acyl analogs of sorbistin.

Sorbistin A1 (1b) and sorbistin B (1a), bioactive components of a new type of aminoglycoside antibiotic produced by a strain of Pseudomonas species, have been converted into a key intermediate 3 by blocking of the 1- and 4-amino groups of sorbistins with dimedone and subsequent deacylation of the 4'-N-acyl group. Some 4'-N-acyl analogs of sorbistin (1e approximately 1t) have been synthesized by 4'-N-acylation of 3 with an appropriate reactive derivative of carboxylic acids (mixed anhydride, acid chloride or activated ester) followed by deblocking of the protected group with bromine or sodium nitrite. Chemical interconversion of three natural sorbistins A1 (1b), A2 (1c) and B (1a) has been performed by this procedure. The 1-N-acyl (4a approximately 4c) and the 1,4'-N,N-diacyl analogs (6a approximately 6c) have been prepared by direct N-acylation of sorbistin D (1d) (the 4'-desacyl derivative) and sorbistin A1, respectively. On the other hand, the 4-N-acyl (5a and 5b) and the 4,4'-N,N-diacyl derivatives (7a and 7b) have been prepared by acylation and subsequent hydrogenolysis of 1-N-Cbz-sorbistin D (4b) and 1-N-Cbz-sorbistin A1 (6b), respectively. Determination of in vitro antimicrobial activity showed that the 4'-N-propionyl (1b) and the 4'-N-cyclopropylcarbonyl (1s) derivatives are the most active members of the 4'-N-acyl derivatives. Elongation and shortening of the side chain and introduction of functional groups decreased the activity. N-Acylation of the amino group at C-1 or at C-4 gave virtually inactive products.

Acylation↗
PubMed1976

Chemical modification of streptovaricin C I. 19-O-substituted damavaricin C.

Damavaricin C, a degradative derivative of streptovaricin C, has reduced antibiotic activity relative to streptovaricin C. It has, however, a new phenolic hydroxyl group at the C-19 position of the naphthoquinone ring on which various groups can be substituted through an ether linkage. A series of 19-O-substituted derivatives of damavaricin C has been synthesized. The preparation of these derivatives, their in vitro antibacterial activities, in vitro inhibition of E. coli RNA polymerase, and lethal activity on the membrane mutants of E. coli are reported. It is believed that the original biological activity of damavaricin C is retained and that introduction of the functional groups at the C-19 position has increased the membrane diffusibility of the molecule.

Bacteria↗