Inhibitors of NADPH oxidase as guides to its mechanism.
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Binding Sites↗
Biomedical subjects
L M Henderson
Publications and source records attributed to L M Henderson.
Recombination of pseudorabies virus vaccine strains in swine.
We report here genetic recombination between 2 USDA-licensed vaccine strains of pseudorabies virus co-inoculated into swine. The vaccine strains, one of which was a conventionally attenuated strain and the other, a genetically engineered deleted strain containing a negative immunologic marker, had complementary genomes. Co-inoculation resulted in the creation of novel strains of pseudorabies virus containing negative immunologic markers with restored virulence genes. Plaque-purified recombinant progeny viruses were found in 2 litters of pigs in which both strains were co-inoculated IM, a litter in which both strains were co-inoculated oronasally, and a litter in which the conventionally attenuated strain was inoculated oronasally and the genetically engineered strain was inoculated IM. Recombinant phenotypes and recombinant restriction fragment patterns were observed. The creation, spread, and potential misdiagnosis of these types of recombinant strains could disrupt control and eradication programs that are based on the serologic identification of swine infected with potentially virulent strains of pseudorabies virus.
Animals↗
Recombination in vivo of pseudorabies vaccine strains to produce new virus strains.
Herpesvirus suis (pseudorabies virus, PRV) has been the focus of intensive genetic engineering efforts and several effective genetically recombinant modified live virus PRV vaccines have resulted. The likelihood and consequences of complementation and/or genetic recombination in vivo between genetically engineered and conventionally derived vaccine strains of PRV are essentially unknown. In this study, two vaccine strains of PRV with complementary gene deletions were co-inoculated into sheep. It reports that avirulent vaccine strains of PRV (genetically engineered and conventionally attenuated) recombined in vivo, resulting in the production of a new and undesirable strain of PRV. The present study exemplifies the need for thorough assessment of genetically engineered micro-organisms in the animal environment.
Animals↗
Long-term double masked trial of early treatment with L-dopa plus bromocriptine versus L-dopa alone in Parkinson's disease. Interim results.
The quality and duration of control in two groups of parkinsonian patients under treatment with an L-dopa-based drug alone or L-dopa-based drug which has been partially substituted with bromocriptine are being compared over a 5-year period using a double-blind placebo-controlled study design. The aim is to establish whether early addition of bromocriptine will minimise late L-dopa complications. Results are presented after 1 year. Of 31 patients randomised, 13 were treated with combined L-dopa/bromocriptine and 14 with L-dopa/placebo. 4 patients were withdrawn for various reasons. In both groups any dose adjustments were aimed at maintaining the pre-entry clinical condition. In the group receiving bromocriptine combination therapy, progressive reduction of L-dopa was possible without deterioration of the patients' condition. In patients receiving L-dopa alone, the dose of L-dopa at 12 months was almost similar to that recorded on entry to the study. The total number of patients reporting adverse events in the L-dopa/bromocriptine combination and L-dopa alone groups were 8 and 7, respectively. At the present interim stage of the study it is not possible to compare the incidence of L-dopa long-term complications in either group.
Bromocriptine↗
Exposure of pigs to a pseudorabies virus formed by in vivo recombination of two vaccine strains in sheep.
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Animals↗
Superoxide generation by EBV-transformed B lymphocytes. Activation by IL-1 beta, TNF-alpha and receptor independent stimuli.
The generation of superoxide by Epstein-Barr virus (EBV)-transformed human B lymphocytes can be stimulated by a range of compounds; receptor-dependent stimuli include tumour necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and lipopolysaccharides (LPS), and independent stimuli include AlF3, A21387 and ionomycin. The stimuli suggest that the activation pathway for the lymphocyte oxidase is similar to that proposed for the neutrophil oxidase. Although the rate of superoxide production was lower than that by neutrophils, the respiratory burst was much prolonged. It is possible that this superoxide generation by lymphocytes may have a biological function.
B-Lymphocytes↗
In vivo and in vitro genetic recombination between conventional and gene-deleted vaccine strains of pseudorabies virus.
Pseudorabies virus (PRV), an alpha-herpesvirus, causes substantial economic losses in the swine industry and is currently the focus of eradication and control programs. Some of these programs rely on the ability of veterinarians to differentiate animals exposed to virulent strains of PRV from animals exposed to avirulent vaccine strains of PRV on the basis of a serologic response to nonessential glycoproteins that are deleted in some vaccine strains of PRV. Genetic recombination resulting in the creation of virulent strains of PRV with the same negative immunologic markers as vaccine strains could disrupt these programs. Two strains of PRV were coinoculated either into tissue culture or into sheep to facilitate recombination. Progeny viruses were selected to detect a specific recombinant phenotype. We were able to detect genetic recombination between vaccine strains of PRV following in vitro or in vivo coinoculation of 2 strains of PRV. The selected recombinants had marker-deleted phenotypes in strains with restored virulence genes. Increased virulence was observed in sheep after coinoculation of 2 avirulent vaccine strains of PRV.
Animals↗
Navajo Indian dental neglect intervention program.
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Adolescent↗
Superoxide generation is inhibited by phospholipase A2 inhibitors. Role for phospholipase A2 in the activation of the NADPH oxidase.
The stimulation of O2.- generation by phorbol 12-myristate 13-acetate (PMA) in human neutrophil-derived cytoplasts was inhibited by a variety of phospholipase A2 inhibitors in a concentration-dependent manner. Inhibition was found to be independent of the order of addition of the inhibitor and PMA. The most potent inhibitor, RO 31-4639, inhibited O2.- generation with an IC50 value (concentration causing 50% inhibition) of 1.5 microM. The addition of either arachidonic acid or SDS, in the presence of the inhibitors, was able to restore O2.- generation. The results suggest that arachidonic acid, released by phospholipase A2, is necessary for both the activation and the maintenance of O2.- generation by the NADPH oxidase.
Acetophenones↗
Superoxide generation by the electrogenic NADPH oxidase of human neutrophils is limited by the movement of a compensating charge.
The ability of the NADPH oxidase of human neutrophil-derived cytoplasts to generate O2.-anions on the addition of phorbol 12-myristate 13-acetate is severely reduced in the presence of valinomycin and Zn2+ ions. The addition of NH4Cl or carbonyl cyanide m-chlorophenylhydrazone (K+ medium only) to these cytoplasts results in a restoration of O2.- generation. At an elevated pHo CCCP restores a greater rate of O2.- generation. Increasing the concentration of Zn2+ ions reduces the extent of the generation of O2.- on the addition of PMA. The restoration of O2.- generation by NH4Cl or CCCP requires the presence of valinomycin. The restoration of O2.- generation appears to be dependent on the movement of NH4+ ions or the anionic form of the uncoupler across the plasma membrane. The activity of the electrogenic NADPH oxidase of cytoplasts is limited by the movement of an ion to act as a compensator. The NADPH oxidase therefore exhibits respiratory control.
Ammonium Chloride↗
Internal pH changes associated with the activity of NADPH oxidase of human neutrophils. Further evidence for the presence of an H+ conducting channel.
The internal pH (pHi) of cytoplasts, derived from human neutrophils, falls 0.05 pH units upon activation of the superoxide-generating NADPH oxidase. The decrease in pHi is absent in diphenyleneiodonium-treated cytoplasts and therefore it is likely to arise directly from the activity of the oxidase. The addition of amiloride, to diminish the Na+/H+ exchanger, enhanced the extent of the internal acidification but not the initial rate. However the electroneutral Na+/H+ exchanger cannot be a contributor to H+ efflux to compensate for charge translocated by the oxidase. In the presence of Cd ions or valinomycin, phorbol-induced acidification of the cytosol was greatly increased, suggesting an inability to translocate the cytosolic H+ generated by an electrogenic oxidase. In the presence of both Cd and valinomycin the cytoplasts retained 0.8 H+ per O2-. generated. The rate of acidification of the external medium by stimulated cytoplasts is greatly reduced in the presence of Zn and valinomycin. Our results support the view that the plasma membrane of neutrophils contains Zn2+- or Cd2+-sensitive proton-conducting channels which maintain a stable membrane potential and pHi during the activity of the electrogenic NADPH oxidase.
Cadmium↗
The superoxide-generating NADPH oxidase of human neutrophils is electrogenic and associated with an H+ channel.
The membrane potential of cytoplasts, derived from human neutrophils, was depolarized by the activation of the superoxide-generating NADPH-dependent oxidase. The extent of the depolarization was inhibited by diphenylene iodonium and was therefore due directly to the activity of the oxidase, which must be electrogenic. The extent of the depolarization was influenced by alteration of the delta pH across the cytoplast membrane, indicating that the outward translocation of H+ eventually compensates for superoxide generation. The depolarization of the potential is enhanced by Cd2+, a blocker of H+ currents, suggesting that the compensatory movement is via an H+ channel.
Biological Transport↗
Uptake of L-carnitine, D-carnitine and acetyl-L-carnitine by isolated guinea-pig enterocytes.
Uptake and metabolism of L-carnitine, D-carnitine and acetyl-L-carnitine were studied utilizing isolated guinea-pig enterocytes. Uptake of the D- and L-isomers of carnitine was temperature dependent. Uptake of L-[14C]carnitine by jejunal cells was sodium dependent since replacement by lithium, potassium or choline greatly reduced uptake. L- and D-carnitine developed intracellular to extracellular concentration gradients for total carnitine (free plus acetylated) of 2.7 and 1.4, respectively. However, acetylation of L-carnitine accounted almost entirely for the difference between uptake of L- and D-carnitine. About 60% of the intracellular label was acetyl-L-carnitine after 30 min, and the remainder was free L-carnitine. No other products were observed. D-Carnitine was not metabolized. Acetyl-L-carnitine was deacetylated during or immediately after uptake into intestinal cells and a portion of this newly formed intracellular free carnitine was apparently reacetylated. L-Carnitine and D-carnitine transport (after adjustment for metabolism and diffusion) were evaluated over a concentration range of 2-1000 microM. Km values of 6-7 microM and 5 microM, were estimated for L- and D-carnitine, respectively. Ileal-cell uptake was about half that found for jejunal cells, but the labeled intracellular acetylcarnitine-to-carnitine ratios were similar for both cell populations. Carnitine transport by guinea-pig enterocytes demonstrate characteristics of a carrier-mediated process since it was inhibited by D-carnitine and trimethylaminobutyrate, as well as being temperature and concentration dependent. The process appears to be facilitated diffusion rather than active transport since L-carnitine did not develop a significant concentration gradient, and was unaffected by ouabain or actinomycin A.
Acetylation↗
Lack of discernible effect of diagnostic ultrasound on the chromosomes of cord blood lymphocytes exposed in utero.
The levels of either sister chromatid exchanges or chromosome breakage (as assayed by the frequency of micronuclei) in cord blood lymphocytes from a total of 62 babies were analysed. The exposure of these babies to ultrasound during gestation was determined retrospectively from medical records and the data reclassified accordingly. No correlation was seen between the levels of chromosome breakage, as measured by these two end-points, and exposure to ultrasound.
Animals↗
Cells from an immunodeficient patient (46BR) with a defect in DNA ligation are hypomutable but hypersensitive to the induction of sister chromatid exchanges.
A fibroblast cell strain, 46BR, derived from an immunodeficient patient is hypersensitive to the lethal effects of a wide range of DNA-damaging agents. It is also defective in strand-break rejoining after treatment with dimethyl sulfate and UV light. The present study shows that the cells have a defect in joining Okazaki-type fragments during DNA replication, supporting the interpretation that the basic defect is in ligation of DNA strands. The baseline level of sister chromatid exchange is slightly higher than in normal cells but it does not approach that of Bloom's syndrome or dyskeratosis congenita cells. Sensitivity to the induction of sister chromatid exchange and the hypersensitivity to the lethal effects of a set of DNA-damaging agents are correlated, implying that the basic defect influences both end points in a similar manner. No 6-thioguanine-resistant mutants could be induced by either gamma- or UV-irradiation in these cells, suggesting that error-prone repair pathways for damage induced by these agents may contain a common ligation step in human cells.
Cells, Cultured↗
Spelling instruction in special education classrooms: a survey of practices.
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Education, Special↗
Absorption of D- and L-carnitine by the intestine and kidney tubule in the rat.
The process by which L- and D-carnitine are absorbed was investigated using the live rat and the isolated vascularly perfused intestine. A lumenal dose of 2-6 nmol in the perfused intestine resulted in less than 5% transport of either isomer to the perfusate in 30 min. The L-isomer was taken up by the intestinal tissue about twice as rapidly as the D-isomer by both the perfused intestine (52.8% and 21.6%, respectively) and the live animal (80% and 50%, respectively) in 30 min. After 1 h 90% of the L-carnitine had accumulated in the intestinal tissue and was released to the circulation over the next several hours. Accumulation of D-carnitine reached a maximum of 80% in 2 h and release to the circulations was similar to that of L-carnitine. Uptake of both L-[14C]carnitine and acetyl-L-[14C]carnitine was more rapid in the upper jejunal segment than in other portions of the small intestine. Acetylation occurred in all segments, resulting in nearly 50% conversion to this derivative in 5 min. Increasing the dose of L-carnitine reduced the percent acetylation. The uptake of both isomers was a saturable process and high concentrations of D-carnitine, acetyl-L-carnitine and trimethylaminobutyrate inhibited L-carnitine uptake. In the live animal after 5 h, the distribution of isotope from L-[14C]carnitine and D-[3H]carnitine differed primarily in the muscle where 29.5% of the L-carnitine and 5.3% of the D-carnitine was found and in the urine where 2.9% of the L-carnitine and 7.1% of the D-carnitine was found. The renal threshold for L-carnitine was 80 microM and for D-carnitine 30 microM, in the isolated perfused kidney. Approx. 40% of the L-carnitine but none of the D-carnitine excreted in the urine was acetylated. L-Carnitine and D-carnitine competed for tubular reabsorption.
Acetylation↗