Glycolytic enzyme activities in malignant cells grown in vitro and in vivo

Cell proximity has a profound effect on the glycolytic enzyme levels observed in mammalian cells grown in vitro. Hexokinase activity generally increased with the increasing cell density of both untransformed and virus-transformed cultures. In contrast, phosphofructokinase and pyruvate kinase activities were generally elevated only in crowded cultures of transformed cells. A spontaneous experimental mouse tumor cell line (EMT6) exhibited cell crowding-dependent elevations in glycolytic enzyme levels when cultured in vitro. The glycolytic enzyme levels of experimental mouse tumors grown in vivo, on the other hand, were constant and normally less than those observed in cultured EMT6 cells.

Deoxyribonucleic acid synthesis, cell cycle progression, and division of Chlamydia-infected HeLa 229 cells

The fate of lymphogranuloma venereum strain Chlamydia-infected HeLa 229 cells was examined by determining the rate of deoxyribonucleic acid synthesis and the kinetics of entry into and progression through S phase and by time-lapse cinemicrography. At an input multiplicity of 5 or less, Chlamydia-infected cells showed no inhibition of host deoxyribonucleic acid synthesis or cell cycle progression. Cinemicrography showed division of inclusion-containing cells, with one or both daughters receiving chlamydial inclusions. Analysis of the family trees indicated that the generation times of infected HeLa 229 were not altered relative to those of the uninfected cells.

Some observations on the nature of reactive groups involved in reversal of mycobacillin inhibition by sterols and lipids

Antifungal action of di- and triacetyl derivatives of mycobacillin is not antagonised by cholesterol or lecithin which antagonise the action of its heptamethyl derivative. Considering the reactive groups of mycobacillin, the antagonism may involve the tyrosine hydroxyl groups of the antibiotic and the 3-hydroxyl group of cholesterol of the oleic acid component of lecithin having unsaturation at the 9:10 position with cis-configuration.

Evaluation of mycobacillin and versicolin as agricultural fungicides. III. Growth pattern and antibiotic production in soil by Aspergillus versicolor

Soil supports the growth of a jute pathogen Colletotrichum gloeosporioides but only to a limited extent that of its antagonist Aspergillus versicolor. The growth of the sensitive pathogen is considerably checked by the antagonist in mixed soil culture although versicolin production could not be demonstrated within the limits of assay. Both the sensitive and the antagonistic organisms grow well in soil-compost medium and versicolin production by the latter is also enhanced. The antagonistic effect of Aspergillus versicolor on Colletotrichum gloeosporioides is expectedly more marked in soil-compost medium than in soil medium.

Evaluation of mycobacillin and versicolin as agricultural fungicides. II. Stability in soil

The effect of paddy soils on mycobacillin and versicolin was investigated. Soil inactivated mycobacillin as determined by spectral analysis and microbiological assay. Soil can inactive mycobacillin only at or above the threshold concentration (125 approximately 130 mug per 10 mg of soil), the excess being unreacted. No new peak appears in the ultraviolet spectrum (240 approximately 300 nm) while mycobacillin is inactivated. Soil is without any effect on versicolin.

In vitro and in vivo evaluation of versicolin, an antifungal antibiotic

Versicolin is mainly active against Trichophyton rubrum. It is inactivated by serum. However, attainable blood level can be fifteen to twenty times higher than the fungicidal concentration for as long as 4 hours after a single intravenous administration of the maximum tolerable dose of 25 mg/kg body weight of mouse. It has no haemolytic activity like other polypeptide antibiotics. Skin does not show the presence of any measurable amount of the antibiotic. It is excreted through urine to the extent of 65% of the maximum tolerable dose of the antibiotic administered intravenously. Versicolin is effective against experimental infection by T. rubrum in guinea pigs at dose as low as 2.5 mg/kg body weight. The antibiotic shows no sign of subacute toxicity at these curative doses.

Evaluation of mycobacillin and versicolin as agricultural fungicides. I. Antifungal spectrum and phytotoxicity

Two antifungal antibiotics, mycobacillin and versicolin, were studied as agricultural fungicides in the control of fungal infection of rice and jute. Mycobacillin is especially active against Piricularia oryzae at a concentration of 10 mug/ml, and versicolin against Colletotrichum gloeosporioides at a concentration of 2.5 mug/ml. Mycobacillin has no adverse effect on germination of seeds and growth of seedlings of rice and jute plants as a concentration of 500ppm, even for prolonged exposure. (24 or 48 hours); in fact, it is stimulatory. On the other hand, versicolin has showed detectable phytotoxicity at 500ppm for prolonged exposure

Requirement for cellular protein synthesis in reversal of ethidium-bormide-induced inhibition of cell transformation by murine sarcoma virus

Cultures of mouse Balb 3T3 fibroblasts exposed to a noncytotoxic dose of ethidium bromide for 16-18 hr are unable to produce foci after infection with murine sarcoma virus. Such cultures regain susceptibility to infection when incubated for 6-8 hr in drug-free growth medium. Pretreated but not untreated cultures exhibit sensitivity toward brief (6 hr) exposure to cycloheximide, chloramphenicol, and actinomycin D before infection. Pretreatment with cordy-cepin inhibits the ability of cultures to produce foci after infection. The recovery of ethidium-bromide-treated cultures requires the synthesis of cellular proteins which may have some important role in the establishment of RNA tumor virus infection.

Growth-and density-dependent inhibition of deoxyglucose transport in Balb 3T3 cells and its absence in cells transformed by murine sarcoma virus

The earliest measurable parameter that shows density-dependent inhibition is the uptake of [(3)H]deoxyglucose by Balb 3T3 cells. The rate decreases even during the exponential phase of growth and reaches a minimum, about 8- to 10-times lower than maximum, as the culture approaches the saturation density. Cells transformed by murine sarcoma virus fail to show either growth-dependent or density-dependent inhibition of deoxyglucose uptake. Treatment with dibutyryl cyclic AMP in the presence of theophylline results in premature cessation of growth and in an arrest in the decline of deoxyglucose transport. Culture in serum-deficient medium also produces rapid inhibition of growth at low cell density, but these cultures exhibit a markedly decreased rate of deoxyglucose uptake.