Low Concentrations Of Streptomycin Research Articles

ПОЛУЧЕНИЕ АКТИВНОГО УГЛЯ ИЗ РАСТИТЕЛЬНЫХ ОСТАТКОВ И ОЦЕНКА ЕГО АДСОРБЦИОННЫХ СВОЙСТВ

On the basis of plant waste formed after extraction of the root and rhizome of Siberian ginseng, by gas activation was obtained samples of the activated carbon, for which defined pore volume and content of acidic and alkali groups. Shows the possibility of using the adsorption method for the extraction of antibiotics from aqueous solutions and wastewater for example, streptomycin. In comparative evaluation of equilibrium, adsorption of streptomycin from model wastewater shown that the obtained activated carbon at low concentration values practically does not differ much from industrial activated carbon with developed dimensional structure (such SKT-type) and can be recommended for practical applications in wastewater treatment. It was found that at concentrations of streptomycin in water less than 100 mg ∙ dm -3 use the additionally oxidized activated carbon is not expedient as adsorbent. To calculate the equilibrium adsorption of streptomycin on obtained activated carbon is proposed to use the equation Dubinin – Radushkevich with the experimentally determined constants; linear form of the equations of Langmuir and Brunauer, Emmett, Teller (BET) during adsorption at low concentrations of streptomycin on the obtained sample are not complied, which limits their use in the calculated practice.It was determined that the higher values of the adsorption activity of the investigated sample activated carbon is achieved during process of adsorption treatment in a neutral to slightly alkaline solutions.

Two Functional Guanidine Groups Are Responsible For the Biological Activity of Streptomycin and Functionally Equivalent Molecules

sc ) via hydrogen bond transfer between each of the guanidine groups and amino acids on one or several peptides and so increases the apparent molecular weight of the protein. With increased quantities and incubation with the PrP sc for one hour at 37°C; these molecules form multimolecular protein aggregates and allowed its recovery via a low centrifugation step. Also other consequences of these interactions are either a drop or even a complete reduction of the prion PrP sc infectivity. These molecules though their interaction with microbes provoked an anti-bacterial activity. The guanidine-containing compounds constitute a very important class of therapeutic agents suitable for the treatment of a wide spectrum of diseases as well as disinfecting agents. Several molecules possesses two guanidine groups as streptomycin, dihydrostreptomycin, triethylenetetramine, bis-3-aminoproylamine, guanidine hydrochloride, and spermine tetra-hydrochloride. The presence of these 2 functional guanidine groups within a non-polymeric hydrophilic molecular system was suspected to be the chemical structure of streptomycin implicated in the interaction with proteins [1]. This interaction takes place through hydrogen bond transfer among the 2 guanidine groups on streptomycin and the amino-acids of one or several prion peptides. The addition of low concentration of streptomycin to a constant amount of non-soluble fraction of the infectious prion protein (PrP sc ) followed by electrophoresis on polyacrylamide gel and immuno detection revealed an increase in the apparent molecular mass of each of the three bands and this increase of the protein molecular mass was proportional to the added streptomycin quantity. When higher streptomycin concentration were added and incubated with PrP sc for one hour at 37°C aggregation and flocculation of the prion protein occurred due to cross-linking by such a proportionally small streptomycin molecule and the PrP sc

An improved procedure for protoplast microelectrofusion and culture of Nicotiana tabacum intraspecific somatic hybrids : plant regeneration and initial proofs on organelle segregation

Somatic hybrids were produced between haploid Nicotiana tabacum L. cv. Petite Havana (wild type) and haploid streptomycin resistant (SR1) mutant by an improved version of microelectrofusion of preselected pairs of protoplasts and the culture of fusion products in a nurse culture. Resistance of diploid plants regenerated from 20 somatic hybrid clones was tested at low concentration of streptomycin in the light as well as at high concentrations of streptomycin in the dark. In two independent hybrid lines, plants resistant in the light but sensitive in the dark were found. The existence of this plant type indicates a segregation of chloroplasts and mitocondria in somatic hybrid clones. It is suggested that microelectrofusion of preselected pairs of protoplasts combined with a reliable nurse culture might be a good technique for controlled somatic hybridization, cell reconstitution and partial gene transfer to different plant species. It might also be used to follow and analyse organelle segregation in somatic hybrid clones. The possibility that mitochondria might be resistant to streptomycin in the SR1 mutant is also discussed.

Error propagation in viable cells

Error propagation is the process, predicted by theoretical models, whereby errors in translating the genetic code will beget fresh errors in successive generations. It has been postulated that error propagation may underly the mortality of cells which display clonal senescence. We have demonstrated the occurrence of error propagation in viable cells of E. coli during growth in a low concentration of streptomycin, a drug which promotes ribosomal ambiguity. We monitored error propagation by measuring mistranslation of a specific UAA codon, and measured viability by direct enumeration of both live and dead cells through a sensitive microscopic technique. We find that the error frequency may be artificially increased by at least an order of magnitude without generating any detectable increase in the proportion of dead cells or of cells whose descendents are doomed to clonal senescence. The error frequency increases gradually over the course of a few generations, in qualitative agreement with the notion of error propagation, and eventually stabilizes at a constant value much higher than normal. The kinetics of this increase agree quantitatively with the Hoffman-Kirkwood and Holliday formulation of error propagation, for parameter values which dictate convergence to a stable error frequency. This convergent behaviour, under conditions of enhanced mistranslation, demonstrates that the normal parameters are well removed from the region of instability in error propagation; even an order of magnitude increase in mistranslation does not tip the translation system into the unstable mode which has been postulated to underly cell senescence. Thus, the error catastrophe theory of cell senescence cannot apply to the translation system of bacteria. We have reviewed experimental data on the fidelity of translation in somatic cells of higher organisms which militate against the notion that the translation system in these cell types could be much closer to the region of instability than in bacteria. These considerations controvert the error catastrophe theory of cell senescence.

Mistranslation in E. coli

Flagellin, the protomeric subunit of bacterial flagella, contains no cysteine. We have detected the incorporation of trace quantities of 35S-cysteine into flagellin, highly purified and then resolved by SDS polyacrylamide gel electrophoresis, to measure mistranslation in vivo. Under normal conditions, this value is about 6 × 10 −4 pmoles cysteine per pmole flagellin. This value is greatly increased during growth in low concentrations of streptomycin and neomycin, antibiotics which are known to stimulate misreading in vitro. Of the specific types of misreading which streptomycin stimulates in vitro, only misreading of the CGU and CGC arginine codons could give rise to illegitimate incorporation of cysteine. In agreement, partial arginine starvation increases the incorporation of 35S-cysteine into flagellin in a relA mutant, with or without streptomycin, but has no such effect in its isogenic relA + partner. Assuming from these results that 35S-cysteine incorporation into flagellin reflects misreading of CGU/C coda, we deduce a misreading probability per codon in the range of 10 −4.

Streptomycin lethality and cyclic AMP

The action of low and moderate concentrations of streptomycin has been studied with Escherichia coli B growing in synthetic media with glucose or glycerol as the carbon source. The inception of lethality depended on the carbon source and the presence of cyclic AMP or ATP in the growth medium. At low concentration of streptomycin (2.5 μg/ml), cells in salts-glycerol media lost their viability following two and a half hour lag period. Glucose repressed the bactericidal effect of streptomycin allowing the cells to grow normally although at a slightly reduced rate. The addition of cyclic AMP to the growth medium reversed glucose repression and rendered the cells sensitive to the action of the drug. At higher concentrations of streptomycin (up to 20 μg/ml) glucose and ATP prolonged and glycerol and cyclic AMP shortened the lag before the cells began to lose their viability. At streptomycin concentration of 5 μg/ml, ATP protected the cells against the bactericidal effect of the drug allowing them to grow normally. This effect of ATP could be abolished by the addition of cyclic AMP. At streptomycin concentrations above 20 μg/ml, the effect of glucose, cyclic AMP and ATP was no longer measurable.

Phenotypic suppression in Escherichia coli by chloramphenicol and other reversible inhibitors of the ribosome.

Antibiotics that interfere reversibly with various aspects of ribosomal function (chloramphenicol, tetracycline, erythromycin, and spectinomycin) are shown to antagonize, at barely inhibitory concentrations, the inhibitory effect of low concentrations of streptomycin (SM) on the growth of Escherichia coli. Paradoxically, these compounds can also replace SM in supporting the growth of conditionally SM-dependent mutants. Chloramphenicol produced about as much phenotypic suppression as SM in SM-sensitive strains, but less than that attainable with high concentrations of SM in resistant strains. The antagonism to SM inhibition and the phenotypic suppression appear to be specific for those growth inhibitors that act on the ribosome. Since inhibitors of the 50S subunit of the ribosome (chloramphenicol, erythromycin) are as active as inhibitors of the 30S subunit, it is suggested that phenotypic suppression by borderline concentrations of ribosome inhibitors does not necessarily depend on an alteration of the recognition region of the ribosome. Alternatively, partial inhibition of the ribosomes might change the environment in a way that would influence the frequency of misreading. Phenotypic suppression by a low concentration of SM as well as by chloramphenicol was found to depend on the presence of a trace of the required growth factor.

The effect of streptomycin on the synthesis of proline in Escherichia coli

Streptomycin inhibits the synthesis of proline in sensitive cells of Escherichia coli W. Inhibition occurs in the conversion of glutamic acid to glutamic γ-semialdehyde. A low concentration of streptomycin causes inhibition in cells subject to end-product control of the proline pathway, and a higher concentration of antibiotic is required to cause inhibition in cells not subject to this control. Streptomycin-dependent strains of bacteria require streptomycin for the production of proline. Two mechanisms are proposed to explain these observations. 1. 1. Inhibition of protein synthesis by streptomycin causes internal end-product inhibition of the proline pathway in wild-type cells. 2. 2. Binding of streptomycin to the cell membrance causes additional inhibition of synthesis in control deficient strains.

Development of resistance to streptomycin by Bact, lactis aerogenes (Aerobacter aerogenes). II. A comparison of mutants of different origins.

Streptomycin-resistant strains ofBact.lactis aerogeneshave been obtained by (a) direct selection in a minimal salt-glucose medium containing 1 unit/ml. streptomycin (strainRs1). (b) indirect selection in the absence of streptomycin with the replica plating technique (strainRrp). (c) irradiation with ultra-violet light (strainRuv). The rate at which colonies develop when these three strains respectively are inoculated on to minimal agar plates containing 1000 u/ml. streptomycin has been subjected to statistical comparison. The results suggest that a basic similarity exists between the strains. Experiments designed to investigate the possible specific induction of resistance by low concentrations of streptomycin in phosphate buffer suspensions of the organism yielded negative results.

Effect of streptomycin on phosphate and nucleic acid metabolism of Escherichia coli

1. 1. Normal Escherichia coli cells can grow in a phosphate-deficient medium, but cells grown for the first time in a streptomycin-containing medium cannot grow in the phosphate-deficient medium. 2. 2. The phosphate incorporation by phosphate-starved streptomycin-sensitive cells is strongly inhibited by a low concentration of streptomycin. 3. 3. In contrast to the phosphate-starved cells, phosphate incorporation by normal streptomycin-sensitive or streptomycin-resistant cells is not inhibited by streptomycin. 4. 4. In contrast to the cells grown in streptomycin-free medium, the cells grown in the streptomycin-containing medium cannot utilize their ribonucleic acid for growth during phosphate starvation.

Mechanism of vegetative hybridization in Streptomyces.

A population of Streptomyces griseus, strain W107, exposed for several growth cycles to a sterile culture filtrate of S. griseus, strain M142, acquired several genetic characteristics similar to those of strain M142. The changes observed were: (1) streptomycin sensitivity to resistance; (2) bacteriophage V1 sensitivity to resistance; (3) absence to presence of soluble pigment; (4) presence to absence of pigment in the vegetative mycelium. The filtrate contained streptomycin and a temperate bacteriophage. The low concentration of streptomycin did not grossly inhibit the growth of strain W107 but streptomycin-resistant mutants were selected. Resistance to the temperate phage frequently conferred resistance to bacteriophage V1. The observed morphological changes were coupled with bacteriophage- and streptomycin-susceptibility. Vegetative hybridization was the result of selection of mutants rather than gene transfer.

Topical use of streptomycin in wounds

1. 1. For topical application to wounds, a solution of streptomycin of the proper concentration should be used, not the powder. Freshly wounded tissues are not damaged further and wounds heal without interference when the concentration of streptomycin is at 200 units or micrograms per cc. Granulations are not damaged by 1,000 units per cc. At these concentrations, streptomycin is the best non-toxic antibiotic that has been found to date for gram-negative bacilli. 2. 2. Penicillin, up to 1,000 units, or sulfamylon 5 per cent should always be combined with streptomycin when it is used topically because streptomycin does not have a complete bacterial spectrum at its proper concentration and some susceptible bacteria rapidly acquire resistance to streptomycin alone. 3. 3. Conversely, streptomycin should always be used topically with penicillin because streptomycin kills gram-negative bacilli that penicillin is unable to destroy and these elaborate penicillinase that in turn destroys penicillin. 4. 4. Gram-negative bacilli are almost always present at some time in the evolution of the bacterial flora of wounds even though only a single strain of bacteria may be isolated at one time. Gram-negative bacilli usually dominate the flora of chronically infected wounds, accounting in part for the failure of topical application of penicillin alone in this type of wound. 5. 5. Gram-negative bacilli definitely interfere with the healing of wounds despite arguments that have been advanced that they are mere contaminants of pus. 6. 6. Because of its stability, sulfamylon 5 per cent makes a better combination with streptomycin than with penicillin. Sulfamylon has a wider bacterial spectrum than penicillin though it is not always as powerful and it acts rapidly in the presence of pus. It can be used with any form of parenteral therapy. This mixture encounters few resistant strains of bacteria. 7. 7. Topically, the solution of streptomycin and penicillin or sulfamylon will prevent infection in wounds better than it will hasten the resolution of established infection, except in certain instances in which no slough is present. 8. 8. In the presence of crushed tissue, prevention of infection can be obtained experimentally until three hours after wounding by washing the wound and injecting about 20 cc. of the solution in the surrounding tissues. With débridement of crushed tissue, prevention of infection has been effected as late as forty-eight hours after wounding when the solution is employed in the same manner. 9. 9. All devitalized tissue cannot be débrided from traumatic wounds nor can the process always be done in time; therefore, topical application of the solution of streptomycin and penicillin or sulfamylon is recommended in the treatment of traumatic wounds as a safety factor to prevent infection. 10. 10. The solution of streptomycin and penicillin or sulfamylon will decontaminate the clean-contaminated operative wound. The solution is applied topically before the wound is closed as one would an antiseptic to the skin. 11. 11. To hasten resolution of the established localized infection in the wound, adjunct chemotherapy in addition to antibacterial chemotherapy is required. This adjunct chemotherapy must liquefy slough and cause the antibacterial substances to penetrate and kill bacteria in slough and leukocytes. 12. 12. A mixture of acid, glycerine and thymol has been used for this adjunct chemotherapy. It is successful when sloughing fascia is present but it is not successful in the presence of osteomyelitis. 13. 13. Streptomycin alone can rid wounds of persistent gram-negative bacilli infection when no slough is present in the wound. For example, granulations that will not take skin grafts because they harbor a flora of the gram-negative bacilli can be freed of these bacteria by the local application of streptomycin and then skin grafts will take. 14. 14. No otic complications have been observed with the low concentration of streptomycin used topically. However, topical therapy has not been used as frequently nor over such long periods of time as parenteral therapy.