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Biomedical subjects

L Kato

Publications and source records attributed to L Kato.

At least 55 records · Page 3Linked to original sources
PubMed1966

Limited multiplication of Mycobacterium lepraemurium in parabiotic culture, as influenced by osmolarity of an alkaline-galactomannan medium.

Kato, Laszlo (Institut de Microbiologie et d'Hygiène de l'Université de Montréal, Montreal, Quebec, Canada), and Bela Gozsy. Limited multiplication of Mycobacterium lepraemurium in parabiotic culture, as influenced by osmolarity of an alkaline-galactomannan medium. J. Bacteriol. 91:1859-1862. 1966.-Limited multiplication of Mycobacterium lepraemurium has been achieved in an alkaline (pH 8.4) galactomannan-containing medium, when cultivated alone or in parabiosis with a feeder strain, Torula minuta. Hyperosmolarity (NaCl, 2.0%) enhanced multiplication in both cases. With 2.0% NaCl in the medium, selective lysis of the feeder cells occurred, without damage to M. lepraemurium. Multiplication depends more on the physical properties (viscosity, hyperosmolarity, and alkaline pH) of the medium than on its chemical composition. The described conditions are proposed as a model for cultivation trials with other "apparently noncultivable" microorganisms.

Galactose↗
PubMedDate not supplied

Separation of Mycobacterium lepraemurium from the subcutaneous tissues of the rat.

In an effort to obtain cell suspensions free from blood cells which interfere in spectrophotometric studies, a method was devised by which relatively large quantities of whole cell suspensions of M. lepraemurium are obtained for experimental purposes. We have routinely employed this procedure which is quite reliable, technically simple, moderate in equipment requirements, and in a matter of five minutes it can be ascertained whether or not the preparations are free from contaminants which render the purified bacillary suspensions unsuitable for studies involving spectrophotometric technics. However, in this procedure, certain points are essential in order to obtain large quantities of purified bacillary suspensions. It is important to homogenize the lepromata for only a few seconds at brief intervals. Excessive homogenization may cause considerable damage to the bacilli and it may be difficult to separate the bacilli from the host tissues. It is also important to use transparent bottles and tubes during centrifugation as the material can be seen and thus each fraction can be separated easily. Very few bacilli are lost in the discarded material and we have repeatedly obtained 2.5 to 3 gm wet weight of M. lepraemurium from one leproma weighing 25 gm to 30 gm.

Animals↗
PubMedDate not supplied

Cholesterol dynamics in macrophages implication for the bacteriology and pathology of leprosy.

M. leprae in the host multiplies abundantly in macrophages rich in cholesterol. Host-grown leprosy bacilli have an extremely high cholesterol content and in this respect they occupy a unique place among procariotic cells. M. leprae takes up cholesterol from the environment and it is not clear whether it can synthesize cholesterol and if so from which precursors. Mycobacteria can be grown from leprous tissues in primary cultures only in the presence of cholesterol. These strains quickly adapt to in vitro substrates and are able to synthesize cholesterol from still-unknown chemical entities, which are also sources of carbon and energy. These still unknown substrates will probably have to be discovered before cultivation of these elusive microorganisms is achieved and we approach a better understanding of the chemical mediators in the cellular defence and/or pathology of leprosy.

Adaptation, Physiological↗
PubMedDate not supplied

Mycobacterium leprae: atypical and unclassified.

Once M. leprae is grown on artificial media in the test tube, it might prove to have a great variety of characteristics quite different to those expected from our knowledge of M. leprae isolated from the susceptible host. The cultures might be slow or fast growing, pigmented or colorless, pathogenic for the armadillo, or not; they might produce limited disease in the foot pad of mice, or the contrary. The in vitro M. leprae culture might or might not provoke a lepromine reaction; the culture might grow at a lower or higher temperature. It is well documented that mycobacteria show great differences in elasticity and adaptability to cultivation conditions. It is absolutely certain that once grown in a test tube, M. leprae will behave as an atypical species. However, each individual culture of M. leprae obtained in vitro will have the same drug sensitivity pattern as in the lepromatous leprosy patient from whom it was cultivated.

Adaptation, Physiological↗
PubMedDate not supplied

Cytochrome-linked respiration in host grown M. leprae isolated from an Armadillo (Dasypus novemcinctus, L.).

The bacilli were isolated from an armadillo (Dasypus novemcinctus, L.) and cytochrome systems as well as oxidation of succinate and NADH by M. leprae were studied. Cell-free extracts of M. leprae contained cytochromes of the a + a3, b, c and o type. Whole cell suspensions catalyzed the oxidation of succinate. The process was unaffected by rotenone but was markedly inhibited by thenoyltrifluoroacetone, antimycin A and cyanide. Cell-free preparations of M. leprae also oxidized NADH with oxygen as the terminal electron acceptor. Although NADH oxidation was completely inhibited by rotenone, the process was inhibited to only 50% by 5 millimols cyanide. The results indicated that complete respiratory system is present in M. leprae isolated from leprous tissues of an armadillo. The effect of inhibitors on succinate and NADH oxidations showed that the respiration in host-grown M. leprae is mediated through the cytochrome system with oxygen as the final electron acceptor.

Animals↗
PubMedDate not supplied

The leprosy bacillus: a microbe-dependent microbe.

Since the discovery of the leprosy bacillus, cultivable mycobacteria were regularly found in lepratic tissues of humans and armadillos. Unpublished data indicate that Professor Hugo Preisz isolated and collected several cultures of unidentified cultivable strains of mycobacteria from leprosy sufferers. Recent findings suggest that Mycobacterium leprae is a microbe-dependent, mycobactin-deficient microorganism. The author proposes the concept that secondary mycobacteria found in leprosy cases are ethilogical cofactors in the pathogenesis of leprosy. Since secondary mycobacteria are rich in mycobactin, it is suggested that they provide the essential mycobactin for growth multiplication and virulence for the mycobactin deficient leprosy bacilli. The implications of this concept are discussed.

Bacteriological Techniques↗