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Biomedical subjects

M Kondo

Publications and source records attributed to M Kondo.

At least 1,459 records · Page 81Linked to original sources
PubMed1977

Studies on the bacterial spore coat. 6. Effects of alkali extraction on the spore of Bacillus thiaminolyticus.

Thin sections of the spore of Bacillus thiaminolyticus Matsukawa and Misawa show a characteristic surface structure with five ridges, and a series of three distinct layers. The outer layer of the spore coat was peeled off by SDS sonic treatment, and then the middle layer was solubilized by alkali extraction of the SDS sonic-treated spore. The spores subjected to these treatments were still refractile, heat resistant, and contained dipicolinic acid, but lost their resistance to mechanical shock.

Bacillus↗
PubMed1976

Selective resistance to desiccation of nuclear ribonucleic acid synthesis in isolated nuclei of Artemia salina embryos during pre-emergence development.

The developing gastrula embryos of Artemia salina are resistant to a complete redesiccation during a period of pre-emergence development. Isolated nuclei from these dehydrated embryos could retain a transcriptional activity in vitro comparable with that of non-desiccated controls. On the other hand, redesiccation of both prenauplii and nauplii completely destroys their viability as well as the nuclear transcriptional activity. However, those gastrula embryos that did not develop in a first incubation period could remain viable and develop with a considerable time-lag after a subsequent second incubation.

Animals↗
PubMed1976

The structure of Artemia salina haemoglobins. A comparative characterisation of four naupliar and adult heamoglobins.

Haemoglobins of Artemia salina were investigated during development and the results obtained are summarised as follows. a)A new haemoglobin (haemoglobin N) was induced de novo in the hatching nauplius, but not in the prenauplius nor in the embryo. b)Haemoglobin N seemed not to be synthesised in the adult. c)The adult contained three distinct haemoglobins (haemoglobins I, II and III) in a quantitative ratio of 1:6:3, respectively, and these haemoglobins were not detected in nauplius. d)Isoelectric points determined were 5.7,5.6,5.7, and 5.9 for haemoglobin N, I, II and III, respectively. e)All four haemoglobins contained one large polypeptide (Mr= 1.1-1.3 X 10(5)) and possibly two minir polypeptides (Mr = 8-9.5 X 10(4) and Mr = 5.4 X qo(4), respectively).

Animals↗
PubMed1976

Preferential inhibition by poly(adenylic acid) of minus-strand synthesis by bacteriophage Qbeta ribonucleic acid replicase.

Among the homopolymers examined, poly(A) was found to inhibit preferentially the synthesis of the minus strand by bacteriophage Qbeta RNA replicase in the presence of host factor. A specific interaction of poly(A) with the host factor is suggested to be a principal cause for the observed preferential inhibition by poly(A) of the host-factor-requiring Qbeta RNA replicase reaction.

Adenosine Monophosphate↗
PubMed1976

Synthesis and some properties and antitumor effects of the actinomycin lactam analog, (di(1-L-alpha, beta-diaminopropionic))actinomycin D1.

A lactam analog of actinomycin D (AMD) has been synthesized as a potential antitumor chemotherapeutic agent. Both L-threonine residues were replaced by L-alpha,beta-diaminopropionic acid. Starting with Nalpha-benzyloxycarbonyl-Nbeta-tert-butyloxycarbonyl-L-alpha,beta-diaminopropionic acid methyl ester hydrochloride the linear intermediate Nalpha-benzyloxycarbonyl-Nbeta-(tert-butyloxycarbonylsarcosyl-L-N-methylvalyl)-L-alpha,beta-diaminopropionyl-D-valyl-L-proline p-nitrophenyl ester was prepared by conventional methods of peptide synthesis in solution. Selective cleavage of the Nbeta-tert-butyloxycarbonyl group and lactam formation afforded the desired cyclic pentapeptide derivative. The chromophore precursor, Nalpha-(2-nitro-3-benzyloxy-4-methylbenzoyl) substituent, was introduced via its symmetric anhydride. Catalytic reduction followed by ferricyanide-mediated phenoxazinone formation provided the lactam analog, [di(1'-L-alpha,beta-diaminopionic acid)]actinomycin D ([Dpr1]2-AMD). Its binding to natural and synthetic DNA and that of an analogous L-threo-alpha,beta-diaminobutyric acid containing lactam ([Dbu1]2-AMD) compared with the binding of AMD (in which the peptides are in lactone form) was studied by circular dichroic (CD) spectroscopy. The visible and uv CD spectra of free AMD differed from those of the free lactam analogs, indicating that the asymmetric environment of the pentapeptide rings in the region of the chromophore differs in free actinomycin lactone and lactams. In the presence of calf thymus DNA, PM2 DNA, and the synthetic d(A-T)-like copolymers containing 2,6-diaminopurine (DAP), poly[d(DAP-T)], and poly[d(DAP-A-T)], the rotational strengths of the optically active transitions in the visible region of the actinomycins increased, and the CD spectra in the presence of the various DNA duplexes were qualitatively similar. The CD spectra of bound actinomycin lactams resembled the spectrum of bound AMD. This suggests that the lactone and lactam actinomycins acquire a similar environment when bound to DNA. [Dpr1]2-AMD was less cytotoxic than AMD in antibacterial assays but exhibited somewhat higher toxicity in mice than AMD. At optimal dose levels the lactam analog had little or no antitumor activity in three murine tumor systems.

Animals↗
PubMed1976

Tissue plasminogen activator in the pathogenesis of protein-losing gastroenteropathy.

Tissue fibrinolytic activity, mainly due to activator of tissue plasminogen was increased in the biopsied gastric mucosa of patients with protein-losing gastropathy. Antiplasmin therapy with trans-AMCHA (trans-4-aminomethyl cyclohexane carboxylic acid) was dramatically effective, except in the case of a patient with intestinal lymphangiectasia. These findings suggest that increased fibrinolysis in the gastrointestinal mucosa may play an important role in enhancing mucosal permeability to plasma proteins.

Adult↗
PubMed1976

Experimental protein-losing gastroenteropathy: role of tissue plasminogen activator.

The tissue fibrinolytic activity of intestinal mucosa was studied in rats with protein-losing gastroenteropathies experimentally produced by X-irradiation, 5-fluorouracil treatment, or ligation of the thoracic duct. The first two models showed an increase of fibrinolytic activity and of 131I-polyvinylpyrrolidone excretion and the third showed normal fibrinolysis. In addition, it was demonstrated that 131I-polyvinylpyrrolidone excretion in the first two groups was markedly reduced by injections of trans-4-aminomethyl cyclohexane carboxylic acid, a potent antiplasmin agent. This finding affords strong support to the authors' previous clinical observation that tissue fibrinolysis in the digestive mucosa plays an important role in the pathogenesis of protein-losing gastroenteropathy associated with diseases of the mucosa.

Animals↗