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Johnson EA. Sacred ground at the bedside: the hospice caregiver as partner of God's compassion. CONNECTICUT MEDICINE 1997; 61:787-8. [PMID: 9465463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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252
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Larson AE, Johnson EA, Barmore CR, Hughes MD. Evaluation of the Botulism Hazard from Vegetables in Modified Atmosphere Packaging. J Food Prot 1997; 60:1208-1214. [PMID: 31207733 DOI: 10.4315/0362-028x-60.10.1208] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The ability of Clostridium botulinum types A, B, and E spores to grow and produce botulinal toxin was investigated in five vegetables (lettuce, cabbage, broccoli, carrots, and green beans) packaged under vacuum or in air. The vegetables were packaged in two types of polyethylene-based bags differing in oxygen and carbon dioxide transmission rates. Vegetables were inoculated with a heat-shocked spore mixture of seven proteolytic and three nonproteolytic strains of C. botulinum types A, B, and E, Inoculated samples and uninoculated controls were incubated at 4, 12, or 21°C. Vegetables were tested for botulinal toxin prior to spoilage, at the onset of spoilage, and after gross spoilage had occurred as evaluated by odor, sliminess and loss of turgidity, gas production, and liquid accumulation in the packages. In nearly all vegetables during incubation the pH decreased, the number of microorganisms increased, the O2 level decreased, and the CO2 level increased. Botulinal toxin was detected in all grossly spoiled broccoli samples incubated at 21°C, in half of the inoculated grossly spoiled broccoli samples incubated at 12°C, and in one-third of the inoculated grossly spoiled lettuce samples incubated at 21°C. The pH of the toxic samples of lettuce and broccoli were 4.48 to 4.88 and 5.72 to 6.62, respectively, and the percent O2 ranged from nondetectable in lettuce to 0.40 to 1.76% in broccoli. The toxic vegetables were considered inedible. No botulinal toxin was detected in any cabbage, carrot, or green bean samples, or in any uninoculated control samples. The data suggest that the probability of botulinal toxin being produced prior to spoilage is less than 1 in 105 in the foods examined.
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Johnson EA, Lin WJ, Zhou YT, Bradshaw M. Characterization of neurotoxin mutants in Clostridium botulinum type A. Clin Infect Dis 1997; 25 Suppl 2:S168-70. [PMID: 9310666 DOI: 10.1086/516239] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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254
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Benjamin BA, Johnson EA. A quantitative description of the Na-K-2Cl cotransporter and its conformity to experimental data. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:F473-82. [PMID: 9321922 DOI: 10.1152/ajprenal.1997.273.3.f473] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In epithelia, the Na-K-2Cl cotransporter cooperates with other transport mechanisms to produce transepithelial NaCl transport. The reaction cycle for the Na-K-2Cl cotransporter has been established experimentally, but whether it accounts, quantitatively, for experimental findings has yet to be established. The differential equations that describe the reaction cycle were formulated, and the steady-state solutions were obtained by digital computation. Conformity between this description and the experimental data obtained from the literature was explored by automatic searches for the sets of rate constants that yielded statistical best-fits to the experimental data. Fits were obtained from renal epithelial cell lines, HeLa cells, and duck erythrocytes. Results show that the reaction cycle for the Na-K-2Cl cotransporter conforms well, quantitatively, with the experimental data.
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255
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Gu WL, An GH, Johnson EA. Ethanol increases carotenoid production in Phaffia rhodozyma. J Ind Microbiol Biotechnol 1997; 19:114-7. [PMID: 9366093 DOI: 10.1038/sj.jim.2900425] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Addition of ethanol (0.2%) to cultures of the yeast Phaffia rhodozyma increased the specific rate of carotenoid production [(carotenoid)(cell mass)-1(time)-1]. The incremental increase in carotenoid synthesis with ethanol was highest in carotenoid-hyperproducing strains. Ethanol increased carotenoid production when it was added at various points during the lag and active growth phases. Ethanol increased alcohol dehydrogenase and hydroxy-methylglutaryl-CoA (HMG-CoA) reductase activities. Our results indicate that increased carotenoid production by ethanol is associated with induction of HMG-CoA reductase and possibly activation of oxidative metabolism.
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256
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Leyer GJ, Johnson EA. Acid adaptation sensitizes Salmonella typhimurium to hypochlorous acid. Appl Environ Microbiol 1997; 63:461-7. [PMID: 9023924 PMCID: PMC168336 DOI: 10.1128/aem.63.2.461-467.1997] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Acid adaptation of Salmonella typhimurium at a pH of 5.0 to 5.8 for one to two cell doublings resulted in marked sensitization of the pathogen to halogen-based sanitizers including chlorine (hypochlorous acid) and iodine. Acid-adapted S. typhimurium was more resistant to an anionic acid sanitizer than was its nonadapted counterpart. A nonselective plating medium of tryptose phosphate agar plus 1% pyruvate was used throughout the study to help recover chemically stressed cells. Mechanisms of HOCl-mediated inactivation of acid-adapted and nonadapted salmonellae were investigated. Hypochlorous acid oxidized a higher percentage of cell surface sulfhydryl groups in acid-adapted cells than in nonadapted cells, and sulfhydryl oxidation was correlated with cell inactivation. HOCl caused severe metabolic disruptions in acid-adapted and nonadapted S. typhimurium, such as respiratory loss and inability to restore the adenylate energy charge from a nutrient-starved state. Sensitization of S. typhimurium to hypochlorous acid by acid adaptation also involved increased permeability of the cell surface because nonadapted cells treated with EDTA became sensitized. The results of this study establish that acid-adapted S. typhimurium cells are highly sensitized to HOCl oxidation and that inactivation by HOCl involves changes in membrane permeability, inability to maintain or restore energy charge, and probably oxidation of essential cellular components. This study provides a basis for improved practical technologies to inactivate Salmonella and implies that acid pretreatment of food plant environments may increase the efficacy of halogen sanitizers.
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Abstract
Monoglycerides (MCs) including MC10, MC12, and coconut MCs were tested for inhibitory activity against Listeria monocytogenes strain Scott A in culture media and in several foods. MCs were inhibitory to L. monocytogenes in certain foods including beef frank slurries (pH 5.0 and 5.5) and seafood salad (pH 4.9) at 4°C, but were less active at 12 than at 4°C. MCs were less inhibitory to L. monocytogenes in other foods tested including turkey frank slurries (pH 5.5), imitation crabmeat, cooked shrimp, summer sausage, yogurt, cottage cheese, and Camembert cheese. Combinations of MCs, particularly MC10 and MC12, showed increased activity in certain foods. The combination of MC10 (250 to 500 μg/ml) and MC12 (250 to 500 μg/ml) or a mixture of coconut-derived MCs (500 to 1,000 μg/ml) were inhibitory against L. monocytogenes in beef and turkey frank slurries. Certain Chemical factors affected the degree of inhibition by the lipid compounds including pH, acidulants such as lactic acid, certain antioxidants, and lipid carriers. The results suggest that MCs could be used as preservatives in certain classes of minimally processed refrigerated foods when intrinsic antimicrobial activity is inadequate.
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258
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Schantz EJ, Johnson EA. Botulinum toxin: the story of its development for the treatment of human disease. PERSPECTIVES IN BIOLOGY AND MEDICINE 1997; 40:317-327. [PMID: 9167258 DOI: 10.1353/pbm.1997.0032] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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259
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Taylor MS, Challed-Spong A, Johnson EA. Co-amplification of the amelogenin and HLA DQ alpha genes: optimization and validation. J Forensic Sci 1997; 42:130-6. [PMID: 8988587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
An optimized PCR-based system allowing the co-amplification of the HLA DQ alpha and the amelogenin genes has been developed and validated, enabling simultaneous identity testing and sex determination. Sensitivities below 100 pg of human DNA were obtained, using a convenient, high resolution agarose gel system and ethidium bromide staining. Comparison of several co-amplification methods revealed that the best sensitivities and most consistent results were obtained using a hotstart technique employing an inactivating antibody to Taq polymerase. HLA DQ alpha typing results were reliably obtained using the co-amplification process. The sensitivity and ease of this system rendered it directly applicable to forensic analyses. The optimized techniques described here have been validated and successfully applied to forensic cases including People vs. Trujillo, in which the California Superior Court accepted these techniques as scientifically reliable and admissible. Work currently in progress has demonstrated that the described protocol may also be used to co-amplify the amelogenin gene with the AmpliType PM (polymarker) system, allowing identity testing at six loci in addition to sex determination.
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260
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Larson AE, Yu RR, Lee OA, Price S, Haas GJ, Johnson EA. Antimicrobial activity of hop extracts against Listeria monocytogenes in media and in food. Int J Food Microbiol 1996; 33:195-207. [PMID: 8930705 DOI: 10.1016/0168-1605(96)01155-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Growth of Listeria monocytogenes was inhibited in culture media and in certain foods by four hop extracts (I-IV) containing varying concentrations of alpha-and beta-acids. Extracts (II and III) containing the highest concentrations of beta-acids were inhibitory at 0.01 mg/l in trypticase soy broth. In food, these hop extracts showed varying magnitudes of inhibition. In coleslaw, hop extract III at 1 mg/g enhanced the rate of inactivation of L. monocytogenes Scott A. Hop extract II was inhibitory at 0.1 and 1 mg/ml in skim and 2% milk, and was inhibitory at 1 mg/ml in whole milk. Hop extract II was listericidal in cottage cheese at 0.1 to 3 g/kg. No inhibition of L. monocytogenes by hop extract III was observed in Camembert cheese. Overall, the antimicrobial activity of hop extracts in food appeared to increase with acidity and lower fat content. Our results indicate that hop extracts could be used to control L. monocytogenes in minimally processed food with low fat content.
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261
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Wu J, Johnson EA, Kootsey JM. A quasi-one-dimensional theory for anisotropic propagation of excitation in cardiac muscle. Biophys J 1996; 71:2427-39. [PMID: 8913583 PMCID: PMC1233732 DOI: 10.1016/s0006-3495(96)79436-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
It has been shown that propagation of excitation in cardiac muscle is anisotropic. Compared to propagation at right angles to the long axes of the fibers, propagation along the long axis is faster, the extracellular action potential (AP) is larger in amplitude, and the intracellular AP has a lower maximum rate of depolarization, a larger time constant of the foot, and a lower peak amplitude. These observations are contrary to the predictions of classical one-dimensional (1-D) cable theory and, thus far, no satisfactory theory for them has been reported. As an alternative description of propagation in cardiac muscle, this study provides a quasi-1-D theory that includes a simplified description of the effects of action currents in extracellular space as well as resistive coupling between surface and deeper fibers in cardiac muscle. In terms of classical 1-D theory, this quasi-1-D theory reveals that the anisotropies in the wave form of the AP arise from modifications in the effective membrane ionic current and capacitance. The theory also shows that it is propagation in the longitudinal, not in the transverse direction that deviates from classical 1-D cable theory.
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Abstract
A patient presented with near complete airway obstruction due to a massive tumor. Nonsurgical methods failed to secure the airway, and surgical approaches were considered unlikely to succeed in a timely fashion. Cardiopulmonary bypass via femoral-femoral cannulation with the use of local anesthesia and a portable unit, followed by IV anesthesia, allowed the surgeons to perform a controlled tracheotomy.
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263
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Hutson RA, Zhou Y, Collins MD, Johnson EA, Hatheway CL, Sugiyama H. Genetic characterization of Clostridium botulinum type A containing silent type B neurotoxin gene sequences. J Biol Chem 1996; 271:10786-92. [PMID: 8631890 DOI: 10.1074/jbc.271.18.10786] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
A recent study detected genes encoding type B botulinum neurotoxin in some type A strains of Clostridium botulinum that exhibit no type B toxin activity. In this study, we investigated the presence, structure, linkage, and organization of genes encoding botulinum neurotoxin (BoNT) and other components of the progenitor complex. Sequence analysis showed that the silent BoNT/B gene is highly related to that from authentic proteolytic type B C. botulinum. However, a stop signal and deletions were found within the sequence. A non-toxin nonhemagglutinin gene (NTNH) was mapped immediately upstream of both the BoNT/A and silent BoNT/B genes. Significantly the NTNH gene adjacent to the defective BoNT/B gene was "chimeric, " the 5'- and 3'-regions of the gene had high homology with corresponding regions of the type B NTNH gene, while the 471-amino acid sequence in the central region was identical to NTNH of type A. Hemagglutinin genes HA-33 and HA-II were not found adjacent to the NTNH/A gene, but instead there was an unidentified open reading frame previously reported in strains of C. botulinum types E and F. By contrast HA-II, HA-33, and NTNH genes were located immediately upstream of the silent BoNT/B gene. Pulsed-field gel electrophoretic analysis of chromosomal DNA digests indicated the distance between type A and B gene clusters to be less than 40 kilobases.
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264
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Johnson EA, Fox JL, Azzaro AJ. The anxiolytic serotonin 5-HT1A receptor agonists buspirone, ipsapirone and gepirone are inhibitors of tyrosine hydroxylation in rat striatum. Behav Brain Res 1995; 73:331-5. [PMID: 8788529 DOI: 10.1016/0166-4328(96)00123-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The anxiolytics buspirone (BUS), ipsapirone (IPSAP) and gepirone (GEP) were investigated as 5-HT1A receptor-mediated inhibitors of tyrosine hydroxylation (TH) in a synaptosome-rich preparation of rat striatum. BUS, IPSAP and GEP were moderately potent inhibitors of TH with EC50 values of 48.4 microM, 50 microM and 836 microM, respectively. By comparison, 8-OH-DPAT, a 5-HT1A receptor selective agonist, has been previously shown to be more potent with an EC50 value of 7.0 microM. Each of these agents demonstrated full agonist activity at the striatal 5-HT1A receptors regulating TH. The inhibitory effects of each agent were attenuated by prior exposure to the 5-HT1A antagonist NAN-190, (10 microM) (P < 0.05), but not by the dopamine D2 antagonist (-)-sulpiride (10 microM). The potencies of 8-OH-DPAT, BUS, IPSAP and GEP were correlated with their reported affinities for the 5-HT1A receptor (P < 0.01) but not the dopamine D2 receptor. These results support the hypothesis that BUS, IPSAP and GEP inhibit TH through activation of a striatal 5-HT1A heteroreceptor on dopamine nerve terminals.
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265
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Lin WJ, Johnson EA. Genome analysis of Clostridium botulinum type A by pulsed-field gel electrophoresis. Appl Environ Microbiol 1995; 61:4441-7. [PMID: 8534108 PMCID: PMC167752 DOI: 10.1128/aem.61.12.4441-4447.1995] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Genomic DNA from type A Clostridium botulinum was digested with restriction endonucleases that cut at rare sites, and the large fragments were separated by pulsed-field gel electrophoresis. Of 15 restriction enzymes tested, MluI, RsrII, SmaI, NruI, KspI, NaeI, and XhoI generated satisfactory digestion patterns of genomic DNA of various C. botulinum strains, enabling the use of the method for genomic fingerprinting. The genomes of four group I (type A) C. botulinum strains examined had similar restriction patterns. However, each strain had unique digestion patterns, reflecting genotypic differences. The genome size of C. botulinum strain 62A was estimated to be 4,039 +/- 40 kbp from the summation of restriction fragments from MluI, RsrII, and SmaI digestions. Genes encoding proteins involved in the toxinogenicity of C. botulinum, including neurotoxin, hemagglutinin A, and genes for a temperate phage, as well as various transposon Tn916 insertion sites in C. botulinum 62A, were mapped by pulsed-field gel electrophoresis. The genes encoding neurotoxin and hemagglutinin A-1, were located on the same fragment in several cases, indicating their probable physical linkage. The macrorestriction analysis established here should be useful for genetic and epidemiological studies of C. botulinum.
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266
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Roseman RR, Johnson EA, Rodesch CK, Bjerke M, Nagoshi RN, Geyer PK. A P element containing suppressor of hairy-wing binding regions has novel properties for mutagenesis in Drosophila melanogaster. Genetics 1995; 141:1061-74. [PMID: 8582613 PMCID: PMC1206830 DOI: 10.1093/genetics/141.3.1061] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
P elements are widely used as insertional mutagens to tag genes, facilitating molecular cloning and analyses. We modified a P element so that it carried two copies of the suppressor of Hairy-wing [su(Hw)] binding regions isolated from the gypsy transposable element. This transposon was mobilized, and the genetic consequences of its insertion were analyzed. Gene expression can be altered by the su(Hw) protein as a result of blocking the interaction between enhancer/silencer elements and their promoter. These effects can occur over long distances and are general. Therefore, a composite transposon (SUPor-P for suppressor-P element) combines the mutagenic efficacy of the gypsy element with the controllable transposition of P elements. We show that, compared to standard P elements, this composite transposon causes an expanded repertoire of mutations and produces alleles that are suppressed by su(Hw) mutations. The large number of heterochromatic insertions obtained is unusual compared to other insertional mutagenesis procedures, indicating that the SUPor-P transposon may be useful for studying the structural and functional properties of heterochromatin.
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267
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Leyer GJ, Wang LL, Johnson EA. Acid adaptation of Escherichia coli O157:H7 increases survival in acidic foods. Appl Environ Microbiol 1995; 61:3752-5. [PMID: 7487011 PMCID: PMC167674 DOI: 10.1128/aem.61.10.3752-3755.1995] [Citation(s) in RCA: 286] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Escherichia coli O157:H7 was adapted to acid by culturing for one to two doublings at pH 5.0. Acid-adapted cells had an increased resistance to lactic acid, survived better than nonadapted cells during a sausage fermentation, and showed enhanced survival in shredded dry salami (pH 5.0) and apple cider (pH 3.4). Acid adaptation is important for the survival of E. coli O157:H7 in acidic foods and should be considered a prerequisite for inocula used in food challenge studies.
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268
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Schroeder WA, Johnson EA. Singlet oxygen and peroxyl radicals regulate carotenoid biosynthesis in Phaffia rhodozyma. J Biol Chem 1995; 270:18374-9. [PMID: 7629161 DOI: 10.1074/jbc.270.31.18374] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Carotenoids have recently received considerable interest because of their potential in delaying or preventing degenerative diseases such as arteriosclerosis, cancer, and aging. In this study we show that the active oxygen species singlet oxygen (1O2) and peroxyl radicals differently affect carotenoid composition and biosynthesis in the yeast Phaffia rhodozyma. Photochemical generation of 1O2 with rose bengal or alpha-terthienyl induced carotenoid accumulation. In contrast, peroxyl radicals derived from t-butylhydroperoxide (tBOOH) or H2O2 decreased the content of astaxanthin and increased beta-carotene by approximately 4-fold, suggesting end product feedback regulation by astaxanthin or inhibition of biosynthetic enzymes. 14C labeling of carotenoids during oxidative stress supported the possibility of end product regulation. Carotenoids were bleached by 8 mM tBOOH within 6 h when carotenogenesis was inhibited by thymol. When treated with peroxides, a previously unreported pigment in P. rhodozyma was formed. The carotenoid had a mass of 580 Da and a molecular formula of C40H52O3. Chemical derivatizations combined with mass and absorbance spectroscopy tentatively identified the carotenoid as dehydroflexixanthin (3,1'-dihydroxy-2,3,3',4'-tetradehydro-1',2'-dihydro-beta,psi-caro tene-4-one). This study provides the first report of induction of astaxanthin biosynthesis by 1O2, probable feedback control by astaxanthin, and the oxidative degradation of astaxanthin to novel pigments in P. rhodozyma.
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269
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Gaertner DJ, Jacoby RO, Johnson EA, Paturzo FX, Smith AL. Persistent rat virus infection in juvenile athymic rats and its modulation by immune serum. LABORATORY ANIMAL SCIENCE 1995; 45:249-253. [PMID: 7650893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In contrast to euthymic juvenile rats, which develop acute, self-limiting infection with rat virus (RV), RV infection of juvenile athymic rats was persistent for up to 12 weeks as demonstrated by recovery of infective virus, transmission to cagemates, and detection of viral DNA in the lungs. Administration of RV antiserum at the time of virus inoculation prevented persistent infection in five of six rats. Among rats given RV antiserum 1 week after virus, the interval at which euthymic rats begin to seroconvert, RV was not detected 1 week later but was recovered from four of six rats 3 weeks later. Results of these studies confirm that T-cell deficiency facilitates persistent RV infection and indicate that antibody provides significant protection from persistent infection only if it is present at the time of virus inoculation. The results support the concept that factors which prevent persistent infection in euthymic rats act early after virus inoculation and may include cellular immunity.
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270
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Jacoby RO, Johnson EA, Ball-Goodrich L, Smith AL, McKisic MD. Characterization of mouse parvovirus infection by in situ hybridization. J Virol 1995; 69:3915-9. [PMID: 7745746 PMCID: PMC189117 DOI: 10.1128/jvi.69.6.3915-3919.1995] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Infection of young adult BALB/cByJ mice with mouse parvovirus-1, a newly recognized, lymphocytotropic, nonpathogenic parvovirus, was examined by in situ hybridization. Virus appeared to enter through the small intestine and was disseminated to the liver and lymphoid tissues. Strand-specific probes detected virion DNA in a consistently larger number of cells than replicative forms of viral DNA and/or viral mRNA. The number of signal-positive cells in the intestinal mucosa, lymph nodes, spleen, and thymus increased through day 10 after oral inoculation but decreased after seroconversion. Positive cells were still detected, however, in peripheral lymphoid tissues of mice examined at 9 weeks postinoculation. The results underscore the need to assess potential effects of persistent mouse parvovirus-1 infection on immune function in mice.
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271
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Zhou Y, Sugiyama H, Nakano H, Johnson EA. The genes for the Clostridium botulinum type G toxin complex are on a plasmid. Infect Immun 1995; 63:2087-91. [PMID: 7729925 PMCID: PMC173270 DOI: 10.1128/iai.63.5.2087-2091.1995] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Clostridium botulinum type G produces a toxin complex that is composed of neurotoxin, hemagglutinin, and nontoxic nonhemagglutinin. The three genes encoding these proteins were closely linked on a plasmid of about 114 kb (76 MDa) but not on chromosomal DNA. In contrast to the genes of other C. botulinum serotypes, the genes encoding type G toxin are on a plasmid.
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272
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Cratty MS, Ward HE, Johnson EA, Azzaro AJ, Birkle DL. Prenatal stress increases corticotropin-releasing factor (CRF) content and release in rat amygdala minces. Brain Res 1995; 675:297-302. [PMID: 7796142 DOI: 10.1016/0006-8993(95)00087-7] [Citation(s) in RCA: 151] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Corticotropin-releasing factor (CRF) is a neuropeptide found throughout the central nervous system that has a proposed role in modulating emotional and behavioral states, including stress and anxiety. The amygdala, which is important in the control of emotional and autonomic responses to stress, contains CRF nerve terminals, CRF cell bodies, and CRF receptors. In rats, exposure to prenatal stress results in offspring that display a hyperemotional state and increased anxiety. In this study the effects of prenatal stress on CRF release was measured in amygdala minces (1 mm3) obtained from adult (8-16 weeks of age) male offspring of dams subjected to daily saline injection (0.1 ml, s.c.) from gestational day 14 to 21. CRF release from amygdala was time- and calcium-dependent, and stimulated by KCl-induced depolarization. Depolarization-induced CRF release was significantly increased by 42% from the amygdala of prenatally stressed offspring versus controls. Prenatally stressed offspring also showed a 49% increase in CRF levels in the amygdala. The increased amounts of CRF released in response to depolarization were likely the consequence of increased tissue content of CRF, as fractional release under basal or KCl-stimulated conditions was not different in the prenatal stress group versus control. This suggests that a long-lasting up-regulation of the CRFergic neurotransmission may occur in the amygdala, which may be important in the generation of hyperemotional offspring after exposure to prenatal stress.
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273
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Pearce LB, Borodic GE, Johnson EA, First ER, MacCallum R. The median paralysis unit: a more pharmacologically relevant unit of biologic activity for botulinum toxin. Toxicon 1995; 33:217-27. [PMID: 7597725 DOI: 10.1016/0041-0101(94)00137-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Although the LD50 has been used to quantify the biologically active toxin in clinical preparations of botulinum A toxin (Botox and Dysport), a discrepancy exists between the clinical potency of equivalent international units of different formulations of botulinum A toxin for multiple clinical indications. Our laboratory previously reported that a regional chemodenervation assay in the mouse could be utilized to detect the difference in the potencies of the clinical preparations of toxin [Pearce et al. (1994) Toxic. appl. Pharmac. 128, 69-77]. The purpose of this study was to quantify the regional paralysis produced by botulinum toxin and define a new pharmacologic/biologic unit of activity that more accurately reflects the mechanism of action of botulinum toxin in the clinical setting. Quantal analysis of regional paralysis revealed that the ED50, defined as the median paralysis unit (MPU) for Botox and Dysport, was 0.41 +/- 0.01 and 1.00 +/- 0.02 LD50 units, respectively. Differences in the potencies found in retrospective clinical studies comparing Botox and Dysport were accurately reflected, for the first time, by the dose of toxin expressed in terms of the MPU (median paralysis unit). The data suggested that the MPU may be a more appropriate measure of the biologic activity in therapeutic formulations of botulinum toxin.
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274
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Johnson EA, Schroeder WA. Microbial carotenoids. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 1995; 53:119-78. [PMID: 8578971 DOI: 10.1007/bfb0102327] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Carotenoids occur universally in photosynthetic organisms but sporadically in nonphotosynthetic bacteria and eukaryotes. The primordial carotenogenic organisms were cyanobacteria and eubacteria that carried out anoxygenic photosynthesis. The phylogeny of carotenogenic organisms is evaluated to describe groups of organisms which could serve as sources of carotenoids. Terrestrial plants, green algae, and red algae acquired stable endosymbionts (probably cyanobacteria) and have a predictable complement of carotenoids compared to prokaryotes, other algae, and higher fungi which have a more diverse array of pigments. Although carotenoids are not synthesized by animals, they are becoming known for their important role in protecting against damage by singlet oxygen and preventing chronic diseases in humans. The growth of aquaculture during the past decade as well as the biological roles of carotenoids in human disease will increase the demand for carotenoids. Microbial synthesis offers a promising method for production of carotenoids.
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Kihm DJ, Leyer GJ, An GH, Johnson EA. Sensitization of heat-treated Listeria monocytogenes to added lysozyme in milk. Appl Environ Microbiol 1994; 60:3854-61. [PMID: 7986052 PMCID: PMC201895 DOI: 10.1128/aem.60.10.3854-3861.1994] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Listeria monocytogenes was highly resistant to hen egg white lysozyme in whole milk but was sensitive in media and in phosphate buffer. Methods to sensitize the pathogen to lysozyme in milk were investigated. Treatment of whole milk by cation exchange to remove minerals, particularly Ca2+ and Mg2+, slightly promoted inactivation of L. monocytogenes by lysozyme at 4 degrees C over a period of 6 days. Heat treatment (62.5 degrees C for 15 s) strongly sensitized L. monocytogenes to lysozyme in demineralized milk and in MES [2-(N-morpholino)ethanesulfonic acid] buffer. Addition of Ca2+ or Mg2+ to the demineralized milk restored resistance to lysozyme. Cells were more rapidly heat inactivated at 55 degrees C in demineralized milk containing lysozyme, and addition of Ca2+ to the demineralized milk restored the resistance to heat. The results indicate that minerals or mineral-associated components protect L. monocytogenes from inactivation by lysozyme and heat in milk, probably by increasing cell surface stability. The heat treatment of foods containing added lysozyme can probably play a significant role in producing microbiologically safe foods.
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