The study of the growth of tylosin producer using differential centrifugation of mycelium in a sucrose density gradient

The mycelium of Streptomyces fradiae was fractionated by differential centrifugation in a sucrose density gradient (SDG) using various samples of the inoculation material and aliquots of the cultural broth taken in the course of tylosin production. The mode of mycelium distribution in SDG made it possible to select the most active inoculation material. The mycelium was redistributed from sucrose layers with a high density to those with a lower density in the course of fermentation. The fractions differed in the antibiotic activity but none of them had an activity higher than in the control centrifuged in 30% sucrose and washed off just like the fractions. Therefore, mycelium fractionation in SDG would not elevate its antibiotic activity. The paper presents the cytological characteristics of different fractions changing in the course of fermentation.     

Sensitivity of Escherichia coli cell membranes to various classes of detergents

The mechanisms of interaction between non-ionic or cationic surfactants with Escherichia coli K-12 cell membranes were studied using an approach based on the registration of changes in the membrane permeability to ethidium bromide, a fluorescent dye for nucleic acids. Triton X-100, a non-ionic detergent, was shown to exert no effect on the permeability of intact cell membranes. Triton X-100 interacted with the bacteria only after treatment with EDTA, a complexing agent for bivalent cations. Cetyltrimethyl ammonium bromide increased the permeability to ethidium bromide and the action of this cationic detergent did not require the pretreatment with the complexing agent. SDS, an anionic detergent, damaged E. coli K-12 and this could be registered by the lowering of intensity of light scattering by the bacterial suspension. The surface charge of E. coli K-12 cells was shown to influence the interaction of ionic detergents with bacterial cell membranes. Its variation by changing the pH of the incubation medium did not make E. coli K-12 sensitive to Triton X-100.     

Methodologic aspects of digital subtraction angiography

The paper is concerned with retrospective analysis of investigations of 1000 patients for standardization of the methodology of computerized subtraction angiography (CSA). Intravenous injection of a contrast medium for visualization of various parts of the arterial system was performed in 374 patients, a selective contrast study of the arteries and veins--in 626. Optimum regimens of injections of a contrast medium, the rate of injection with respect to the site of drug administration, the internal section and length of a catheter were determined. Correlation between a single dose of injection of a contrast medium and the patient's body mass during i. v. CSA was determined. Shortcomings of the method and possibilities for their elimination were mentioned. Some methodological procedures for CSA optimization (a possibility of correlation of the detected changes with anatomical structures and the determination of their actual sizes irrespective of the size of an image obtained) were proposed.     

The effect of picolinic acid and iron ions on the proliferation of SPEV cells

The effect of picolinic acid (PA) on SPEV cell proliferation is found to be different from that on normal and virus transformed NRC cells, and on spontaneously transformed CHO cells. It is shown that SPEV cells are arrested by PA at the end of G1-phase and at the beginning of S-phase and probably in G2-phase of the cell cycle. Ferrous ions remove the G1/S block induced by PA to permit the cell transfer through S-phase. On the one hand, PA chelates ferrous ions from the cells, and on the other one it inhibits the replicative DNA synthesis. It can be suggested that PA may arrest the SPEV cell growth affecting the iron-depend stable radical formation which is introduced into the active centre of ribonucleotiDE reduCTase. This results in the lower enzyme activity.     

The invariance of subjective time scales

Organization of subjective time scales was studied by various methods of duration scaling (reproduction, fractionation, multiplication, evaluation, measuring and cross-model selection). Computation of linear correlation coefficients between physical time and its subjective expression for various methods of scaling in different coordinate systems allows to make a conclusion about a degree form of psychophysical dependence. The value of function degree index varies in the range of 0.80-0.88 for verbal evaluation and 0.93-1.07 for other methods. The concept is suggested about the "active" and "passive" time.     

Antigenic similarity between cytoplasmic tetrodotoxin-sensitive protein and neuronal membrane proteins

Membrane proteins with a molecular weight of 290, 180, and 55 kDa were isolated using immunosorbent attached to sepharose and rabbit antibodies to cytoplasmic tetrodotoxin-sensitive protein from beef brain gray matter. A technique used for research into voltage-dependent sodium channels was applied to reconstruction of these proteins and investigation of toxin-dependent sodium flows through the lipoprotein membrane. Findings are interpreted as evidence of the similarity between cytoplasmic tetrodotoxin-sensitive protein and that of sodium channels at the cell membrane.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev; A. V. Palladin Institute of Biochemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 4, pp. 485–489, July–August, 1989.     

The diagnosis of short penis as a cause of impotentia coeundi in bulls

Short penis condition was diagnosed as the cause of impotentia coeundi in 10 bulls, aged 2.5 to 5 yr. The diagnosis was based on observation of service attempts, measurement of the extended penis, and elimination of other causes of impotence. Measurements of the penis were made under general inhalation anesthesia or pudendal nerve block. These measurements were then compared with those of 10 control bulls, matched for age and breed and having no history of impotence; the latter measurements were likewise obtained under general anesthesia, pudendal nerve block or sedation. with propionyl promazine. Similar measurements were obtained from 10 yearling bulls under propionyl promazine sedation. Measurements obtained under general anesthesia or pudendal nerve block in the same bull were usually similar and repeatable, while phenothiazine tranquillization produced incomplete and variable relaxation of the retractor penis muscles. The dimension best correlated with impotence due to short penis was the distance from the tip of the extended penis to the preputial orifice in its resting position. In 10 bulls in which short penis was diagnosed, this distance was 10 to 22 cm, while in 10 control bulls with no history of impotence it was 25 to 42 cm. The distances from the tip of the extended penis to the preputial reflection (fornix) and to the neck of the scrotum were also shorter in affected than in control bulls. Although observation of service ability remains the cornerstone of diagnosis of short penis, a presumptive diagnosis can be made if penile protrusion of less than 25 cm can be obtained in an adult bull under general anesthesia or pudendal nerve block. Phenothiazine tranquillization is suitable for screening examinations but not for definitive diagnosis.     

Use of benzodiazepines to manipulate the circadian clock regulating behavioral and endocrine rhythms

Extensive studies have now been carried out demonstrating that the systemic administration of the short-acting benzodiazepine, triazolam, can have pronounced effects on both behavioral and endocrine circadian rhythms. For example, three daily injections of triazolam can phase-advance the circadian rhythm of pituitary luteinizing hormone release and locomotor activity by about 2-3 h in female hamsters maintained in constant light. Triazolam has also been found to facilitate the rate of reentrainment of the activity rhythm following an 8-hour advance or delay in the light-dark cycle. Limited studies with other short-acting benzodiazepines indicate that the effects of triazolam on the circadian system of hamsters can be generalized to this class of drugs. Recent studies in humans indicate that treatment with triazolam can alter the time it takes for human endocrine rhythms to become reentrained following an 8-hour delay in the sleep-wake and light-dark cycle. Such findings raise the possibility that short-acting benzodiazepines may prove useful in reducing the symptoms associated with 'jet-lag' and rotating shift-work schedules as well as in the treatment of various physical and mental illnesses that have been associated with a disorder of biological timekeeping.     

Simultaneous analysis of skin response to the different L.E.T. regions of a 55 MeV helium ion beam

Summary Rat tail epidermis was used to analyze the in vivo response of a biological system to heavy particle irradiation. The conical configuration of the rat tail gives rise to a variable energy degradation of the beam thus yielding information on the damage elicited by 2 different L.E.T. regions of the helium beam at different sites on the same sample. Cytochrome oxidase activity and epidermal thickness were used to analyze the metabolic and structural radioinduced response. Quantitative evaluation of radiation damage revealed marked variations within a few micrometers of tissue.