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Results for “Phenylenediamines”

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At least 19 recordsLinked to original sources
PubMed1976

Phenylenediamine restoration of photosynthetic electron flux in DBMIB-inhibited chloroplasts.

Phenylenediamines have been studied and compared as to their effectiveness in stimulating photosynthetic electron flux in DBMIB-inhibited chloroplasts. It has been found that N-substituted as well as C-substituted p-phenylenediamines accelerate the rate of ferricyanide reduction, a photosystem II photoreaction, under conditions where the radical cations of N-substituted p-phenylenediamines are stable. The P/e2 ratios for these partial reactions are between 0.4 and 0.5; this is taken as evidence that N-substituted p-phenylenediamines are reduced by the chloroplasts close to the outer surface. Both N- and C-substituted p-phenylenediamines are capable of bypassing the site of DBMIB inhibition and restoring electron flow from water to methylviologen. N-substituted p-phenylenediamines appear to be more effective even at high concentrations of DBMIB. The P/e2 ratios for these reactions are on the order of 0.75-1.0; this is taken as evidence that the bypass reaction for N-substituted p-phenylenediamines occurs on the inside of the thylakoid membrane.

Chloroplasts↗
PubMed1978

Allergic contact dermatitis due to N,N-dimethyl-para-phenylenediamine in bacteriology technicians.

Three cases of allergic contact dermatitis due to N,N-dimethyl-para-phenylenediamine in a bacteriology laboratory are presented. This chemical, a dye closely related to the common contact allergen para-phenylenediamine, is used in laboratories to screen bacterial culture plates for Neisseria gonorrhoeae. The three patients had strongly positive patch test reactions to N,N-dimethyl-para-phenylenediamine, but had negative reactions to para-phenylenediamine. A brief discussion of allergic contact cross-sensitization among compounds with the para-aminophenyl grouping is presented.

Adult↗
PubMed1977

The use of ruthenium and p-phenylenediamine to stain cartilage simultaneously for light and electron microscopy.

p-Phenylenediamine was incorporated during the dehydration of cartilage blocks fixed with ruthenium red, glutaraldehyde and osmium. The addition of p-phenylenediamine permitted the visualization by light microscopy of cellular detail not obtained with ruthenium red alone. Ruthenium red is a widely used method for retaining and localizing proteoglycan for electron microscopy but its inability to produce sufficient density within the cells for light microscopy prevented simultaneous visualization by these two modes. The addition of p-phenylenediamine staining overcame this shorcoming without interfering with the ultrastructural detail and both stains can also be used before the making of radioautographs.

Animals↗
PubMed1979

Studies on the succinate dehydrogenating system. I. Kinetics of the succinate dehydrogenase interaction with a semiquindiimine radical of N,N,N',N'-tetramethyl-p-phenylenediamine.

1. The activities of the soluble reconstitutively active succinate dehydrogenase (EC 1.3.99.1) measured with three artificial electron acceptors, e.g. ferricyanide, phenazine methosulfate and free radical of N,N,N',N'-tetramethyl-p-phenylenediamine (WB), have been compared. The values estimated by extrapolation to infinite acceptor concentration using double reciprocal plots 1/v versus 1/[acceptor] are nearly the same for ferricyanide and phenazine methosulfate and about twice as high for the WB. 2. The double reciprocal plots 1/v versus 1/[succinate] in the presence of malonate at various concentrations of WB give a series of straight lines intercepting in the third quadrant. The data support the mechanism of the overall reaction, in which the reduced enzyme is oxidized by WB before dissociation of the enzyme-product complex. 3. The dependence of the rate of the overall reaction on WB concentration shows that only one kinetically significant redox site of the soluble succinate dehydrogenase is involved in the reduction of WB. 4. Studies of the change of V and Km values during aerobic inactivation of the soluble enzyme suggest that only 'the low Km ferricyanide reactive site' (Vinogradov, A.D., Gavrikova, E.V. and Goloveshkina, V.G. (1975) Biochem. Biophys, Res. Commun. 65, 1264--1269) is involved in reoxidation of the reduced enzyme by WB. 5. The pH dependence of V for the succinate-WB reductase reaction shows that the group of the enzyme with the pKa value of 6.7 at 22 degrees C is responsible for the reduction of dehydrogenase in the enzyme-substrate complex. 6. When WB interacts with the succinate-ubiquinone region of the respiratory chain, the double reciprocal plot 1/v versus 1/[WB] gives a straight line. The thenoyltrifluoroacetone inhibition of succinate-ubiquinone reductase or extraction of ubiquinone alter the 1/v versus 1/[WB] plots for the curves with a positive initial slope intercepting the ordinate at the same V as in the native particles. The data support the mechanism of succinate-ubiquinone reduction, in which no positive modulation of succinate dehydrogenase by ubiquinone exist in the membrane.

Aerobiosis↗
PubMed1979

Studies on the mutagenicity of p-phenylenediamine in Salmonella typhimurium. Presence of PCB's in rat-liver microsomal fraction induced by Aroclor.

The mutagenicity of fresh solutions of p-phenylenediamine (PPD) and Aroclor 1254 was investigated. The histidine-requiring strains of Salmonella typhimurium were used in the absence and presence of uninduced and/or Aroclor-induced rat-liver homogenate. The presence of polychlorinated biphenyls (PCBs) was also examined by chromatographic methods in Aroclor-induced rat-liver homogenate. In the absence of metabolic activation, as well as in the presence of uninduced rat-liver homogenate, PPD was not mutagenic in the strains used. In the presence of Aroclor-induced S9 a twofold increase (or less) was observed in the number of revertant colonies over those of the controls in TA1538 and TA98. There was no increase in the number of revertant colonies over those of the controls when PPD was dissolved in NH4OH solution and the solution mixed with H2O2 before the addition of S9 mix. Aroclor 1254 was not mutagenic in TA1538 or TA98. However, the presence of PCBs in Aroclor-induced rat-liver homogenate (induced S9) was identified by gas-liquid chromatography (GLC), high-performance liquid chromatography (HPLC) and gas--liquid chromatography/mass spectrometry (GC/MS).

Animals↗
PubMedDate not supplied

Effect of DPPD (diphenyl-para-phenylenediamine) on stroke and cerebral edema in gerbils.

Diphenyl-para-phenylenediamine (DPPD) is an antioxidant that has been shown to decrease liver damage due to the peroxidative process of carbon tetrachloride in rats and to ameliorate cold-induced cerebral edema in cats. Because lipid peroxidation disrupts the integrity of the plasma membrane, a process believed to occur in cerebral infraction, which is a major cause of cerebral edema. DPPD was tested for its protective effect against cerebral infarction. When given intraperitoneally in gerbils with unilateral ligation of the common carotid artery, DPPD had no effect on resultant incidence, morbidity, or mortality of cerebral infarction. Despite these findings, the authors believe, on the basis of what is known about free radical pathology, that DPPD and other antioxidants deserve further laboratory trials as possible drugs in the treatment of brain trauma and cerebral edema.

Animals↗
PubMed1975

[Changes in the muscle fiber induced by p-phenylenediamine in the rat].

P-phenylenediamine (PPD) induces skeletal muscle lesions in rats which have been chosen as a model for investigation of the inflammatory and degenerative pattern of the muscle fibers. With the use of histochemical and ultrastructural criteria, the morphology of the lesions have been analysed in the diaphragm. Fifteen minutes after the induction by PPD, a subsarclemmal oedema can be shown by electron microscopy. Enzymatic changes appear during the first hour. The pathologic features are more prominent after twenty-four hours. The lesions are characterized by a segmental necrosis adjacent to unaltered fibers and by particular types of fibers such as target, snake coils, core fiber. A comparison between the lesions induced by PPD and those occurring during other types of myopathies has been made.

Adenosine Triphosphatases↗
PubMed1975

Tetramethyl-p-phenylenediamine oxidase reaction in Azotobacter vinelandii.

It was possible to quantitate the tetramethyl-p-phenylenediamine (TMPD) oxidase reaction in Azotobacter vinelandii strain O using turbidimetrically standarized resting cell suspensions. The Q(O2) value obtained for whole cell oxidation of ascorbate-TMPD appeared to reflect the full measure of the high respiratory oxidative capability usually exhibited by this genera of organisms. The Q(O2) value for the TMPD oxidase reaction ranged from 1,700 to 2,000 and this value was equivalent to that obtained for the oxidation of the growth substrate, e.g., acetate. The kinetic analyses for TMPD oxidation by whole cells was similar to that obtained for the "particulate" A. vinelandii electron transport particle, that fraction which TMPD oxidase activity is exclusively associated with. Under the conditions used, there appeared to be no permeability problems; TMPD (reduced by ascorbate) readily penetrated the cell and oxidized at a rate comparable to that of the growth substrate. This, however, was not true for the oxidation of another electron donor, 2,6-dichloroindophenol, whose whole cell Q(O2) values, under comparable conditions, were twofold lower. The TMPD oxidase activity in A. vinelandii whole cells was found to be affected by the physiological growth conditions, and resting cells obtained from cells grown on sucrose, either under nitrogen-fixing conditions or on nitrate as the combined nitrogen source, exhibited low TMPD oxidase rates. Such low TMPD oxidase rates were also noted for chemically induced pleomorphic A. vinelandii cells, which suggests that modified growth conditions can (i) alter the nature of the intracellular terminal oxidase formed (or induced), or (ii) alter surface permeability, depending upon the growth conditions used. Preliminary studies on the quantitative TMPD oxidation reaction in mutant whole cells of both Azotobacter and a well-known Mucor bacilliformis strain AY1, deficient in cytochrome oxidase activity, showed this assay can be very useful for detecting respiratory deficiencies in the metabolism of whole cells.

2,6-Dichloroindophenol↗
PubMed1978

Cyanide-insensitive oxidation of ascorbate + NNN'N'-tetramethyl-p-phenylenediamine mixture by mung-bean (Phaseolus aureus) mitochondria. An energy-linked function.

Freshly prepared washed or purified mung-bean (Phaseolus aureus) mitochondria utilize oxygen with ascorbate/tetramethyl-p-phenylenediamine mixture as electron donor in the presence of KCN. ATP control of the oxygen uptake can be observed with very fresh mitochondria. The electron flow, which is inhibited by antimycin A, salicylhydroxamic acid or octylguanidine, takes place by reversed electron transport through phosphorylation site II and thence to oxygen through the cyanide-insensitive pathway. Oligomycin and low concentrations of uncoupler partially inhibit the oxygen uptake in a manner similar to that observed for other energy-linked functions of plant mitochondria. An antimycin A-insensitive oxygen uptake occurs if high concentrations of uncoupler are used, indicating that the pathway of electron flow has been altered. The process of cyanide-insensitive ascorbate oxidation is self-starting, and, since it occurs in the presence of oligomycin, it is concluded that the reaction can be energized by a single energy-conservation site associated with the cyanide-insensitive oxidase pathway.

Ascorbic Acid↗