Antagonistic Phenomena Research Articles

Domain-wall superconductivity in superconductor-ferromagnet hybrids.

Superconductivity and magnetism are two antagonistic cooperative phenomena, and the intriguing problem of their coexistence has been studied for several decades. Recently, artificial hybrid superconductor-ferromagnet systems have been commonly used as model systems to reveal the interplay between competing superconducting and magnetic order parameters, and to verify the existence of new physical phenomena, including the predicted domain-wall superconductivity (DWS). Here we report the experimental observation of DWS in superconductor-ferromagnet hybrids using a niobium film on a BaFe(12)O(19) single crystal. We found that the critical temperature T(c) of the superconductivity nucleation in niobium increases with increasing field until it reaches the saturation field of BaFe(12)O(19). In accordance with the field-shift of the maximum value of T(c), pronounced hysteresis effects have been found in resistive transitions. We argue that the compensation of the applied field by the stray fields of the magnetic domains as well as the change in the domain structure is responsible for the appearance of the DWS and the coexistence of superconductivity and magnetism in the superconductor-ferromagnet hybrids.

Method of detecting β-lactam antibiotic induced vancomycin resistant MRSA (BIVR)

Despite the fact that the combination of vancomycin and a β-lactam antibiotic are known to act synergistically on vancomycin-susceptible Staphylococcus aureus (VSSA), some MRSA have emerged showing antagonism to the combination of vancomycin and a β-lactam antibiotic. These MRSA are called β-lactam antibiotic-induced vancomycin resistant MRSA (BIVR). A method based on this antagonistic phenomenon has been devised to detect BIVR strains. The method inhibits the VSSA strain but allows the BIVR strain to grow. Forty-six commercially available β-lactam antibiotics induced the vancomycin-resistance. Using this detection method, 717 MRSA clinical isolates obtained from eight institutes throughout Japan were thus screened and 6.3% of these were detected as BIVR when judged at 48 h.

Modelización de la deformación en caliente de un cobre puro comercial

The objective of the study is to model the flow curve at high temperature of a commercialpurity copper which contains 297 ppm of phosphorus. For this purpose a theoretical model is applied to derive a constitutive equation that reliably predicts the behaviour at higher strain rates than experimentally tested. The test temperature range was from 873 K to 1223 K in increments of 50 K, using six true strain rates at every temperature, which span from 0.3 s -1 to 0.001 s -1 The hot flow tests were performed on a copper with a relatively large grain size (637 µm) but of similar scale to pertinent industrial processes. This metal presents two antagonistic phenomena during the hot working: strain hardening and softening by dynamic restoration, which in turns can be divided into dynamic recovery and dynamic recrystallization. A quantification of the mentioned mechanisms is done through the use of physically based constitutive equations.

Chemical Diversity Approach for Evaluating Mechanistic Relatedness Among Toxicological Phenomena

The CASE/MULTICASE structure-activity relationship (SAR) system was used to assess a new procedure to investigate the mechanistic relatedness of various toxicological endpoints. The method consisted of predicting the activity of 10,000 randomly selected chemicals using validated and characterized SAR models from a variety of biological and toxicological endpoints. The prevalence of chemicals predicted to possess the ability to induce two or more toxicological effects simultaneously should provide a measure of the mechanistic relatedness of these phenomena. Eight toxicological endpoints were predicted and the results were compared to predictions based on an eye irritation SAR model. Allergic contact dermatitis demonstrated a 29.6% greater than expected overlap between expected and observed results (p < 0.001). Similar results were seen for respiratory hypersensitivity (33.1%), sensory irritation (28.9%), cell toxicity (25.9%), and Ah receptor binding (19.8%). A lesser degree of overlap was seen between eye irritation and Salmonella mutagenicity (11.5%) and the inhibition of gap junction intercellular communication (6.7%). Moreover, a negative overlap, suggesting possibly an antagonistic phenomena, was observed between eye irritation and α2μ-induced nephropathy. These results indicate that this method can provide a useful tool to investigate mechanistic relatedness between diverse toxicological endpoints.

Review in vitro-induced flowering in bamboos

The majority of bamboos (Graminae) are arborescent and perennial. The erect stems (culms) of woody bamboos are useful for a wide variety of purposes. Most bamboos flower only once at the end of very long vegetative growth phases and die afterwards. Flowering in bamboos is thought to be under genetic control, occurring somewhat like an alarm clock, going off at a preset time. The nature of this genetic clock and any interaction between the ‘internal clock’ and the environment are not yet known. Because of this ‘peculiar’ flowering behavior, bamboo seeds are available only at very long intervals. Obtaining concurrent flowering in two or more species (or varieties) in space and time is difficult, making perennial seed propagation and genetic improvement by breeding nearly impossible. Besides, this peculiar flowering behavior of bamboos is also believed to have brought the giant pandas to the verge of extinction. One of the spectacular developments in the area of bamboo genetic improvement has been the precocious in vitro induction of flowering. By this method it has been possible to rapidly accelerate the reproductive development (within 3–6 mo. versus 30–60 yr in nature). This has opened the possibility of perennial seed propagation and hybridization. In vitro induction of flowering can be obtained by diverse methods which show some similarities and differences. Induction of flowering is possible in cultures derived from both juvenile and mature explants. The proportion of seedlings induced to flower is possibly influenced by genotypic variation, though the role of methods used cannot be ruled out. A cytokinin or a shift in the auxin-cytokinin equilibrium is believed to bring about in vitro induction of flowering. The pH of the media also has an influence. Induction of flowering and rhizogenesis is considered to be an antagonistic phenomenon in vitro. A comparison between in vitro and in vivo flowering in Bambusa arundinacea has shown that though smaller, in vitro-induced florets are comparable to normal florets. There is reduced pollen fertility and some impairment in pollen wall development. Biochemical studies on the in vitro-induced flowering in bamboos have shown (1) selective expression of esterase and peroxidase isozymes during transition of nonembryogenic calluses to embryogenic calluses, somatic embryo development, germination and subsequent flowering of somatic embryo derived shoots, and (2) minimal peroxidase activity before rhizogenesis and induction of flowering in vitro. There are reports of published and comparable methods having failed to induce flowering in vitro.

Insecticidal and Genotoxic Activities of Oregano Essential Oils

The essential oils (EOs) obtained from the oregano plants Origanum vulgare subsp. hirtum, Coridothymus capitatus, and Satureja thymbra were examined by a combination of GC and GC−MS and found to be rich in carvacrol, thymol, γ-terpinene, and p-cymene. These EOs and their main constituents, carvacrol and thymol, were tested for insecticidal and genotoxic activities on Drosophila. The EO of S. thymbra was found to be the most effective as an insecticide, while carvacrol was found to be more toxic than thymol. The toxicities of carvacrol and thymol do not correspond to their participation in the EOs, and mixtures of these two phenols in levels resembling their content in the three oils showed that the toxicity of carvacrol was reduced in the presence of thymol, thus suggesting antagonistic phenomena. The somatic mutation and recombination test on Drosophila revealed that, among the five compounds studied, only thymol exhibits genotoxic activity. Keywords: Oregano; Origanum vulgare; Coridothymus capitatus; Satureja thymbra; essential oils; carvacrol; thymol; insecticides; genotoxicity; Drosophila melanogaster

Antagonistic effect of nucleic acid precursors on the anticoccidial activity of 6-azauracil.

The antagonistic phenomena to anticoccidial activities of 6-azauracil (AzU) induced by certain nucleic acid precursors were examined in battery experiments. Each nucleic acid precursor, orotate, orotidine, uracil, uridine, adenine and adenosine was mixed in feed in combination with effective levels of AzU. The test feed was provided through the test term to White Leghorn cockerels which were infected with Eimeria tenella, E. necatrix or E. acervulina. In vitro tests were also conducted for antagonistic phenomena similarly to in vivo test using E. tenella cultured in chick kidney (CK) cells. Orotate and uridine reduced dose-dependently the anticoccidial activity of AzU in E. tenella infection in chickens. Uracil and orotidine revealed similar effect. Adenine and adenosine did not show any antagonistic effect to AzU. In E. necatrix infection, orotate and uridine had a similar tendency to that of E. tenella, whereas uracil and orotidine was less pronounced. The activity of AzU against E. acervulina was also blocked by the treatment with uridine and orotate. AzU inhibited the schizont's development of E. tenella in the CK cells, and this effect was reduced by uridine, but not by orotate and orotidine. The antagonistic effect of the pyrimidine nucleic acid precursors on AzU activity suggested that the anticoccidial effect of AzU to E. tenella, E. necatrix and E. acervulina is derived from inhibition of the metabolism of pyrimidine nucleotide synthesis in these parasites.

Theoretical Study on Synergistic and Antagonistic Phenomena in a Packed Bed Biological Flow Reactor

Theoretical Study on Synergistic and Antagonistic Phenomena in a Packed Bed Biological Flow Reactor

Ferritin: design and formation of an iron-storage molecule

Although essential for most forms of life, too much iron is harmful. To cope with these antagonistic phenomena an iron-storage molecule, ferritin, has evolved. The structure of horse spleen apoferritin, which has recently been refined, consists of 24 symmetrically related subunits forming a near-spherical hollow shell. In ferritin the central cavity is occupied by an iron core of 'ferrihydrite', a geologically ephemeral mineral found in hot or cold springs and in mine workings, or produced in the laboratory by heating solutions of ferric salts. Ferritin itself forms most readily from apoferritin, in the presence of dioxygen, from FeII, not FeIII. Access to its interior is through small intersubunit channels, and the protein influences both the rate of FeII-oxidation and the form of oxide produced.

The effect of the chemical and physical properties of carbon black on the thermal and photooxidation of polyethylene

AbstractThe antioxidant and UV stabilizing effect of different carbon blacks on parafin oil model compound with and without additional stabilizers was investigated. The thermal and photooxistabilities of the samples were characterized by the induction period of the oxygen consumption which was measured volumetrically in a closed system filled with oxygen. A relationship was established between the induction periods of the thermal oxistability curves and the distributions of oxygen content within the active groups of the blacks.Determining the stabilities of the polymer‐black‐antioxidant systems, synergistic and antagonistic phenomena were observed. These effects were explained by taking nto account the quality and amount of the active sites of the blacks.The photooxidation experiments corroborated the double role of the black as UV stabilizer. Primarily it acts as a UV screen, its effectiveness being proportional to its specific surface. In addition to this, the synergism and antagonism observed in the ternary systems suggested that the carbon was also involved in the photooxidation as a chain terminating and peroxide decomposing agent.

Behavior of Macromolecules on the Phase Boundary. II. Conformational Statistics of the Linear Chain in a Pore

The pseudodiffusion equation with a term added by the author to describe the effect of the field of force has been employed in the calculations of the partition function and equilibrium concentration of a dilute solution of linear polymer in pores, the walls of which are formed by a swollen gel and are therefore partly permeable to chainlike macromolecules. The effect of surface forces near the walls of the pores has also been considered. In this way, Casassa's equilibrium theory of gel permeation chromatography (GPC) formulated for pores with inert impermeable walls has been generalized. To simplify the calculations, a quasistationary approximation has been proposed and employed. The equilibrium concentration difference between a pore and the bulk phase of solution is a result of two antagonistic phenomena; i.e., of the decrease in the number of conformations in the walls of the pore, and of attractive adsorption forces. Its sign depends on the values of the following expressions: (d / b)2(φA / kT), φA / φG, and (ν − 1)d / (L − d), where d is the thickness and φA is the potential of the layer of adsorption forces, b is the length of the chain segment, φG is the potential characterizing the interaction of the linear polymer with the gel, L is the radius of the pore, and ν is the geometric characteristic of the pore (ν = 1 for a plane-parallel pore, ν = 2 for a cylinder, ν = 3 for a sphere).

Antagonistic phenomena between crystalline tetrodotoxin and guanidines on sympathetic nervous systems.

The antagonistic phenomena between crystalline tetrodotoxin and guanidine in the sympathetic nerve-smooth muscle preparations were investigated and the following results were obtained. In the hypogastric nerve-vas deferens preparation of the guinea-pig, the contractions of the vas deferens induced by the electrical stimulation of the pre- and post-ganglionic fiber of the hypogastric nerve were suppressed after the administrations of crystalline tetrodotoxin 5×10-8M and procaine 10-4M, and the suppression by tetrodotoxin was antagonized by guanidine 10-3M or methylguanidine 10-3M, and that by procaine was only temporally antagonized. These antagonistic phenomena were observed also on the guinea-pig trachea preparation and the nictitating membrane of cat. In the hypogastric nerve-vas deferens preparation of the guinea-pig, moreover, the contraction which could not be observed in the absence of Na+ in the external solution was recovered by applying guanidine into the solution. From these results, it is concluded that tetrodotoxin and guanidine or methylguanidine would be antagonistic at the presynaptic site of sympathetic nerve ending.

抗生物質耐性乳酸菌に関する研究 (2)

1) The oral administration to a mouse of antibiotics as SM and others gives changes to the fecal bacterial flora, and Yeast-like bacteria having resistive power to these drugs extraordinarily increase, and the susceptibility to the oral infection of salmonella enteritidis enhanced.2) This phenomenon above is remarkably suppressed with the administration of drug resistant Str. fecalis.3) On the suppressive power of Str. fecalis over Yeast-like bacteria according to the result of the examination in vitro of the antagonistic phenomenon of the two, it is considered that the mechanism of the suppresion of Str. fecalis over Yeast-like bacteria is not so much due to acid generated by the former as to the difference of the quantity of their consumptive power of glucose in media.

The antibradykinin action of fibrinolysin and other studies on capillary permeability employing different mediators and synthetic bradykinin

THIS presentat ion enlarges certain comments one of us (A. L. C.) made on several findings repor ted b y Schachter 1 at this Symposium. We found also that plasmin has little or no significant effect in inducing capil lary permeabil i ty. However , we noted that the precursor of plasmin or fibrinolysin, viz. plasminogen, present in the circulating blood, increased markedly capi l lary permeabi l i ty in guinea-pigs and rats, the two species which we employed in our studies. The electron microscopic observations of Schachter 1 appear to some extent to be similar to certain hitherto unpublished studies made recent ly bv Palade and Majno. 2,3,4 A brief account of their work will be given together with that of our findings which led Copley to modify his concept of the endoendothelial fibrin film (EEFF) to include the basement membrane (BM). An a t tempt will be made to explain the ant ibradykinin effect of f ibrinolysin on capil lary permeabi l i ty on the basis of tbis modified concept recent ly proposed 5,G towards a bet ter unders tanding of capil lary permeabi l i ty and fragility, two apparent ly antagonistic phenomena. In an effort to elucidate the role of bradykinin on capil lary permeability, we have extended a number of our previous studies recent ly reported on the integr i ty of the vascular wall and the antagonistic action of fibrinolysis to histamine and serotonin. 5,6 These observations of synthet ic bradykinin are presented together wi th findings of its possible interaction wi th other mediators on capil lary permeabil i ty .

Inhibitory action of fibrinolysin and other proteolytic enzymes on capillary permeability induced by histamine, serotonin and bradykinin

Streptokinase activated human fibrinolysin (plasmin), chloroform activated bovine fibrinolysin, streptokinase, crystalline preparations of trypsin, chymotrypsin and papain inhibited CP, regardless by which of the mediators it was induced in guinea-pigs and rats. The mediators employed were histamine, serotonin and synthetic bradykinin. These findings were secured by the use of the rat's cremaster preparation of Majno and Palade, a qualitative test for CP, and with the blueing reaction, a semi-quantitative test for CP in the ventral regions of the skin, employing Evans blue in the anesthetized guinea-pig and rat. Concomitantly with the marked decrease in CP, petechial hemorrhages were produced demonstrating an increase of CF. These results provide evidence that CP and CF are antagonistic phenomena. This antagonism, as well as the inhibitory action if fibrinolysin and other proteolytic enzymes, can be explaind by Copley's modified concept of the endoendothelial fibrin film. This postulates a special fibrin, also contained in the BM, to be a cement of the capillary wall and fibrinolysis to control the integrity of the vessel wall.

Studies on drug receptors of smooth muscle. V. Reversible antagonists on vascular smooth muscles

Drug receptor in smooth muscles was examined with vascular strips from a guinea pig, chiefly using reversible antagonists, and following facts were revealed.1) Sensitivity of vascular smooth muscles is similar against adrenaline, phenylephrine, histamine, and barium chloride, and a definite dose-response curve was obtained for each agent.2) In general, following antagonistic phenomena were observed with reversible antagonists in vascular smooth muscles.(a) Sympatholytics showed reversible, competitive antagonism against adrenaline but showed reversible, non-competitive antagonism against barium chloride and histamine.(b) Analgesics showed reversible, non-competitive antagonism against adrenaline while anticonvulsants of strong bases, such as Benactyzine, showed a reversible, non-competitive antagonism against barium chloride and those of weak bases, such as papaverine, a reversible competitive antagonism.(c) Vasodilators like sodium nitrite and aminophylline showed reversible, non-competitive antagonism against adrenaline.(d) Parasympatholytics showed reversible, non-competitive antagonism against adrenaline, barium chloride, and histamine.3) The mode of action of various anti-convulsants against vascular smooth muscles, i.e. effectivity ratio of the inhibitory action of various anti-convulsants, and antibarium action suggested that pharmacological properties of vascular smooth muscles is midway between that of tracheal smooth muscles and intestinal smooth muscles.

Antibiotics in the control of plant diseases.

The use of antibiotics is a comparatively new method of plant disease control, but antibiosis, or antagonistic phenomena among microorganisms, and its relation to plant diseases have been recognized for more than 75 years. Gliotoxin, the first antibiotic to be used for plant disease control, was isolated and purified by a plant pathologist even before the discovery of penicillin. In 1932 Weindling (1) noted the antagonism of Gliocladium fimbria tum to a number of fungi. In 1934 he studied (2) a lethal principle produced by this organism and found that it was responsible for the para­ sitic action of G. fimbriatum on Rhizoctonia solani and other soil fungi. Two years later Weindling & Emerson (3) isolated in crystalline form the sub­ stance known as gliotoxin, thus becoming the first to isolate an antibiotic in a pure state. The next report of the control of a plant disease by an anti­ biotic was by Brown & Boyle (4, 5) in 1944. They observed that a crude culture filtrate of Penicillium notalum was effective against crown gall, caused by Agrobacterium tumefaciens. No in vivo evidence of the antibiotic effect of the filtrate on the pathogen was reported, and later studies showed that the effect was largely on the gall tissue. In 1945 Brian & Hemming (6) showed that gliotoxin reduced infection of covered smut of barley, bunt of wheat, and helminthosporium leaf spot of oats. In 1946 Brown & Heep (7) reported the eradication of Xanthomonas pruni from cankers on plum twigs. It was not until 1952, however, that an antibiotic was used under field condi­ tions for the control of plant disease. Zaumeyer et al. (8) showed that beans were protected from infection by the halo blight organism (Pseudomonas phaseolicola) with a streptomycin spray, and Ark (9) reported good control of pear blight (Erwinia amylovora) with a streptomycin dust. Previously, most of the investigations consisted of screening plant patho­ gens in vitro to determine their sensitivity to antibiotics. Although screening tests in vitro demonstrated the effectiveness of a number of antibiotics against many pathogens, tests in vivo frequently failed to corroborate them. This review deals primarily with the control of diseases of plants, under greenhouse and field conditions, by means of the antibiotics which are com­ monly available. Certain compounds which have been studied only a little and are unavailable to growers are not discussed. It is likely that among the large number of papers published in this field, some important ones were over1 The survey of the literature pertaining to this review was concluded in De­ cember, 1957.

Antibiosis in relation to plant diseases.

Pioneers of microbiology and plant pathology (1, 2) were well aware of antagonistic phenomena among microorganisms and their relation to plant disease. But as Fawcett (3) pointed out, effects of known mixtures of cul­ tures were rarely studied i� detail, because pathologists were too deeply impressed by the need of pure culture work which is basic for exploring host­ pathogen relationships. Recently, however, studies of in relation to plant pathology have received a powerful stimulus; antibiotic substances have become a major factor in the treatment of many human diseases. A vast fermentation industry has sprung up to manufacture the wonder drugs of lowly microbial origin. For the searcher after remedies of diseases of humans, animals, or plants, the metabolic products of thousands of fungi, actino­ .mycetes, and bacterial species are providing a new field for exploration. Waksman (4) defined antibiotics as substances produced by microorgan­ isms and' capable of inhibiting or destroying other microorganisms; but related substances of higher-plant origin will be mentioned here also. The terms antibiosis and antagonism have been employed interchangeably in plant pathological literature, and they will be used so here. Antibiosis, then, will refer to all inhibitory or destructive effects of microorganisms on one another, whether defined antibiotic substances are involved or not; it is a collective term that covers widely differing kinds of relations. This review will discuss and antibiotics in relation to plant pathogens and disease contro!' Various aspects of this field have been treated by other reviews (4 to 8). Whatever the true nature of viruses, their behavior as etiological agents of plant diseases is so similar to that of known micro­ organisms that they may properly be considered in a section of this article.

STUDIES IN THE PHYSIOLOGY OF THE NERVOUS SYSTEM. XXI.: RHYTHMIC MOVEMENTS AS SUCCESSIVE (OR TERMINAL) REFLEX PHENOMENA OF COMPOUND STIMULATION [PROGRESSION CONDITIONED BY ANTAGONISTIC REFLEX STIMULI

STUDIES IN THE PHYSIOLOGY OF THE NERVOUS SYSTEM. XXI.: RHYTHMIC MOVEMENTS AS SUCCESSIVE (OR TERMINAL) REFLEX PHENOMENA OF COMPOUND STIMULATION [PROGRESSION CONDITIONED BY ANTAGONISTIC REFLEX STIMULI

The Scientific Study of Starvation 1

TO the non-scientific mind the detailed study of inanition or starvation in men and animals may appear both useless and unnecessary. It is in reality one of the most important pieces of work the investigator of nutrition and allied problems can undertake. In the normal condition the processes of construction (anabolism) and decay (katabolism) are taking place simultaneously, and one can in that condition only obtain the net result of, or balance between, these two antagonistic phenomena. In order to understand the way in which the body builds itself up, it is obviously necessary that we should first know the amount and kind of the breakdown which accojn-panies vital activity, and so logically the study of katabolism must come first. This is only possible when anabolism is minimal; hence arises the importance of the knowledge of what occurs when the intake is limited to oxygen and water.