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S J Harrison

Publications and source records attributed to S J Harrison.

17 recordsLinked to original sources
PubMed1997

Purification, characterisation and cDNA cloning of an antimicrobial peptide from Macadamia integrifolia.

An antimicrobial peptide with no significant amino acid sequence similarity to previously described peptides has been isolated from the nut kernels of Macadcamia integrifolia. The peptide, termed MiAMP1, is highly basic with an estimated pI of 10.1, a mass of 8.1 kDa and contains 76 amino acids including 6 cysteine residues. A cDNA clone containing the entire coding region corresponding to the peptide was obtained. The deduced amino acid sequence of the cDNA indicated a 26-amino-acid signal peptide at the N-terminus of the preprotein. Purified MiAMP1 inhibited the growth of a variety of fungal, oomycete and gram-positive bacterial phytopathogens in vitro. Some pathogens exhibited close to 100% inhibition in less than 1 microM peptide (5 microg/ml). Antimicrobial activity was diminished against most, but not all, microbes in the presence of calcium and potassium chloride salts (1 mM and 50 mM, respectively). MiAMP1 was active against bakers yeast, was inactive against Escherichia coli and was non-toxic to plant and mammalian cells. Analysis of genomic DNA indicated that MiAMP1 was encoded on a single copy gene containing no introns. The MiAMP1 gene may prove useful in genetic manipulations to increase disease resistance in transgenic plants.

Amino Acid Sequence↗
PubMed1997

A peroxidase gene promoter induced by phytopathogens and methyl jasmonate in transgenic plants.

The expression of two closely related peroxidase isogenes, Shpx6a and Shpx6b, of the legume Stylosanthes humilis was studied using isogene-specific reverse transcriptase PCR techniques. Results indicated that transcripts of both genes were rapidly induced following inoculation with the fungal pathogen Colletotrichum gloeosporioides, wounding and treatment with the defense regulator methyl jasmonate (MeJA). In contrast treatment of leaves of S. humilis with abscisic acid (ABA) and salicylic acid (SA) did not induce transcripts of either isogene. A genomic clone containing the Shpx6b gene was isolated and 594 bp of 5' sequence upstream of the translation start was fused in frame to the coding region of the uidA reporter gene and introduced into tobacco. Expression from the Shpx6b promoter in transgenic plants was determined by histochemical staining and quantitative assays of beta-glucuronidase (GUS). In transgenic tobacco, GUS expression was detected in cotyledons, vascular cells of young leaves, anthers, pollen, and the stigma and style. Wounding of the tobacco plants produced very localized GUS staining. Much more extensive staining for GUS was observed following inoculation of tobacco leaves with conidia of the fungal pathogen Cercospora nicotianae and the inoculation of wound sites with mycelium of the Oomycete pathogen Phytophthora parasitica var. nicotianae. Treatment of mature leaves with methyl jasmonate induced GUS activity while treatment with ABA, SA, and H2O2 had no effect. A similar strong induction of GUS activity was measured in young transgenic seedlings germinated on MeJA while some, but much weaker, induction of GUS activity was observed in seedlings treated with SA. The sequence of the promoter contained motifs homologous to putative cis elements in other plant genes responsive to MeJA. The Shpx6b gene is the first plant peroxidase gene shown to be induced by both microbial pathogens and MeJA and its promoter will be useful for investigations of signaling processes during fungal infection and for the expression of foreign gene products at infection sites.

Acetates↗
PubMed1996

Convective warming combined with vasodilator therapy accelerates core rewarming after coronary artery bypass surgery.

In a prospective, randomized, controlled study, we have investigated the effect of forced air warming on the rate of change of nasopharyngeal and rectal temperatures in 20 patients after coronary artery bypass grafting. All patients had nasopharyngeal temperatures less than 36 degrees C on arrival in the intensive care unit and received an infusion of glyceryl trinitrate 15 mg h-1, but none received inotropes. Ten patients were warmed under an aluminized plastic "space" blanket (control group) and 10 were warmed under a "Bair Hugger" blanket connected to its power unit on "high" setting (Bair Hugger group). The rates of increase in nasopharyngeal temperature were 0.4 and 0.95 degrees C h-1, respectively, in the control and Bair Hugger groups (P < 0.01) during the first 2 h after operation. Over the same period of time, rectal temperatures increased at a rate of 0.25 and 0.75 degrees C h-1 in the control and Bair Hugger groups, respectively (P < 0.01).

Aged↗
PubMed1996

Integument and sensillum auriforme of the opisthosoma of Rhipicephalus appendiculatus (Acari:Ixodidae).

The opisthosomal integument and sensilla auriformia of Rhipicephalus appendiculatus Neumann larvae, nymphs, females and males, both unfed, fed, and during molt, were examined by light and electron microscopy in relation to semiochemical production. The integument consists of epidermis, endocuticle, exocuticle, epicuticle, a superficial wax layer and a variable additional deposit. The integument of immature instars and females grows greatly during feeding. The integument is traversed by pore canals from the epidermis to the outer wax canals. The epidermis can secrete material to the exterior by way of the pore canals and wax canals. The sensillum auriforme is a common disk-shaped organ, with a complex internal chamber open to the exterior by way of a pore. It has no apparent secretory capacity and is of presumed sensory function. It is located in the integument of scutum and alloscutum of all instars.

Animals↗
PubMed1996

Integumental glands of the tick Rhipicephalus appendiculatus (Acari:Ixodidae) as potential producers of semiochemicals.

The opisthosomal integument and associated secretory organs of Rhipicephalus appendiculatus Neumann larvae, nymphs, females and males, both unfed and fed were examined by light and electron microscopy. Type 1 dermal glands were found on the alloscutum and scutum of all ticks. They were undeveloped in unfed ticks and reached full development in engorging ticks. They produced secretory granules from 2 glandular cells but without accumulation of a reservoir of secreted material. Type 2 dermal glands were found in all ticks, with pores on the alloscutum, edge of scutum, and on anal plates. These glands produced secretion during feeding and accumulated large reservoirs of secreted material that were present in engorging, recently detached and questing ticks. Spiracular glands were found in all ticks below the spiracle plate. They produced small amounts of secretion and had pores to the exterior by way of spiracle goblets. No obvious cycle of secretory activity was recorded. Foveal glands were present and produced secretions in nymphs, females, and males. They were largest in females with an accumulation of secretory vesicles in feeding ticks. The potential function of these glands is discussed in the context of the chemical ecology of this tick.

Animals↗
PubMed1995

Spontaneous oxygen radical production at sites of antigen challenge in allergic subjects.

Allergic reactions in the lung are characterized by the production of mediators, an influx of inflammatory cells, increased vascular permeability, and changes in airway mechanics. The mechanisms responsible for these airway changes have not been fully defined but may involve the production of reactive oxygen species (ROS) produced by the inflammatory cells. To examine whether ROS are produced by inflammatory cells at sites of antigen exposure, bronchoalveolar lavage (BAL) was performed in airway segments 19 h after challenge with saline or antigen in 14 allergic subjects. Antigen challenge increased cell recovery, predominantly as a result of an influx of eosinophils. Using electron paramagnetic resonance (EPR) spectroscopy with the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), BAL cells from saline-challenged sites produced minimal ROS. Cells from antigen-challenged sites spontaneously produced a prominent DMPO-OH signal that was inhibited by superoxide dismutase (SOD), indicating the production of superoxide anions (O2-.). Reduction of ferricytochrome c and production of luminol-dependent chemiluminescence via SOD-inhibitable reactions confirmed the spontaneous production of O2-. Following density gradient separation of the antigen-challenged BAL cells, the granulocytic cells, which were predominantly eosinophils, not the mononuclear cells, were the major source of the ROS. At the sites of antigen challenge, the degree of airway permeability as assessed by albumin concentration in BAL fluid was correlated with O2- production by BAL cells measured by EPR spectroscopy. These results demonstrate that cells at sites of antigen challenge generate ROS that may contribute to the airway injury associated with allergic inflammation.

Adult↗
PubMed1994

Evidence for a mounting sex pheromone in the brown ear tick Rhipicephalus appendiculatus, Neuman 1901 (Acari: Ixodidae).

The presence of a mounting sex pheromone was demonstrated on the surface of fed female Rhipicephalus appeniculatus. This pheromone, which is present on the female cuticle, allows the male to recognise the female. The pheromone was removed by cleaning the female in hexane, resulting in the loss of male mating behaviour in in vitro experiments. Male mating behaviour was resumed when extract made from fed female cuticle was replaced on cleaned females. When the extract was transferred to inanimate objects typical male mating behaviour was released. Preliminary chemical analyses indicated that the active component of the extract was contained in the sterol ester fraction of the extract.

Animals↗
PubMed1994

A comparative study of EPR spin trapping and cytochrome c reduction techniques for the measurement of superoxide anions.

Superoxide anions (O2.-) generated by the reaction of xanthine with xanthine oxidase were measured by the reduction of cytochrome c and by electron paramagnetic resonance (EPR) spectroscopy using the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). Studies were performed to determine the relative sensitivities of these two techniques for the measurement of O2.-. Mixtures of xanthine, xanthine oxidase, and DMPO generated two adducts, a transient DMPO-OOH and a smaller but longer-lived DMPO-OH. Both adducts were inhibited by superoxide dismutase (SOD), demonstrating they originated from O2.-, and were also significantly decreased when the experiments were performed using unchelated buffers, suggesting that metal ion impurities in unchelated buffers alter the formation or degradation of DMPO-adducts. O2.-, generated by concentrations of xanthine as low as 0.05 microM, were detectable using EPR spin trapping. In contrast, mixtures of xanthine, xanthine oxidase, and cytochrome c measured spectrophotometrically at 550 nm demonstrated that concentrations of xanthine above 1 microM were required to produce measurable levels of reduced cytochrome c. These studies demonstrate that spin trapping using DMPO was at least 20-fold more sensitive than the reduction of cytochrome c for the measurement of superoxide anions. However, at levels of superoxide generation where cytochrome c provides a linear measurement of production, EPR spin trapping may underestimate radical production, probably due to degradation of DMPO radical adducts.

Cyclic N-Oxides↗
PubMed1993

Hyperoxic sheep pulmonary microvascular endothelial cells generate free radicals via mitochondrial electron transport.

Free radical generation by hyperoxic endothelial cells was studied using electron paramagnetic resonance (EPR) spectroscopy and the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). Studies were performed to determine the radical species produced, whether mitochondrial electron transport was involved, and the effect of the radical generation on cell mortality. Sheep pulmonary microvascular endothelial cell suspensions exposed to 100% O2 for 30 min exhibited prominent DMPO-OH and, occasionally, additional smaller DMPO-R signals thought to arise from the trapping of superoxide anion (O2-.), hydroxyl (.OH), and alkyl (.R) radicals. Superoxide dismutase (SOD) quenched both signals suggesting that the observed radicals were derived from O2-.. Studies with deferoxamine suggested that the generation of .R occurred secondary to the formation of .OH from O2-. via an iron-mediated Fenton reaction. Blocking mitochondrial electron transport with rotenone (20 microM) markedly decreased radical generation. Cell mortality increased slightly in oxygen-exposed cells. This increase was not significantly altered by SOD or deferoxamine, nor was it different from the mortality observed in air-exposed cells. These results suggest that endothelial cells exposed to hyperoxia for 30 min produce free radicals via mitochondrial electron transport, but under the conditions of these experiments, this radical generation did not appear cause cell death.

Animals↗
PubMed1983

Cel vinyls: materials and methods.

Many commercial uses of media are applicable to medical/scientific media production and illustration, not the least of which are techniques pioneered in the commercial cartooning field. Whether or not the illustrative effort culminates in a "cartoon," the production techniques of the cartooning industry cannot be overlooked by the illustrator faced with providing projection graphics, whether animated or still, for slides, motion pictures, television or even print media. When Walt Disney introduced Mickey Mouse as "Steamboat Willie" in 1928, his technology opened the door for exploration of cartooning media by all artists. Only in comparatively recent years have these tools been used by the scientific illustrator. In this article cel vinyl acrylics or cartoon colors will be discussed: the rationale for the use of this medium, materials and methods, and considerations related to the photography of this art form.

Cartoons as Topic↗
PubMed1980

Limulus amoebocyte lysate assay for detection and quantitation of endotoxin in a small-volume parenteral product.

A Limulus amoebocyte lysate gel-clotting method for the determination of endotoxin in a small-volume parenteral product has been described. Sample dilution with 0.1 M potassium phosphate monobasic buffer (pH 8.0) effectively eliminated assay interference, whereas dilution with water did not. The threshold pyrogenic dose for Escherichia coli EC-2 and O127:B8 endotoxins was determined to be 1.0 ng of endotoxin per kg of body weight. Not more than 1.0 ng of endotoxin (the threshold pyrogenic dose) per the highest recommended human dose or the USP pyrogen test dose per kg of body weight, whichever dose is more stringent, is a logical limit for the quantity of bacterial endotoxin in small-volume parenteral products. Excellent correlation was attained when this criterion was used to compare the Limulus amoebocyte lysate assay with the USP pyrogen test.

Animals↗
PubMed1979

Application of LAL for detection of endotoxin in antibiotic preparations.

The Limulus amebocyte lysate (LAL) test has been investigated as an alternative method to the USP pyrogen test for the detection of endotoxin contamination in these antibiotic preparations: clindamycin phosphate, lincomycin hydrochloride, neomycin sulfate, and spectinomycin hydrochloride. The antibiotic preparations were tested at the maximum concentrations that would not inhibit gelation of LAL. The USP pyrogen test was also performed for comparison. The LAL and the USP pyrogen tests correlated extremely well when an acceptance criterion based on the minimum pyrogenic dose (MPD) of endotoxin per human dose of drug was used for the LAL test. Use of this MPD provides a practical and feasible acceptance creiterion for the LAL test and assures that the LAL sensitivity approximates or surpasses that of the USP pyrogen test.

Animals↗
PubMed1979

Limulus amebocyte lysate - a means to monitor inactivation of lipopolysaccharide.

A properly selected Limulus Amebocyte Lysate (LAL) has been demonstrated to have a good correlation with the in vivo United States Pharmacopeial pyrogen test when testing lipopolysaccharide (LPS) inactivated with ethylene oxide, 60 Co irradiation, and dry-heat treatments. Thus, LAL may be used to determine degradation or depyrogenation kinetics of LPS. A criteria for acceptance of an LAL lot for correlation with the USP pyrogen test is described.

Animals↗
PubMed1978

Dry-heat destruction of lipopolysaccharide: dry-heat destruction kinetics.

Dry-heat destruction kinetics of lipopolysaccharides from Escherichia coli, Serratia marcescens, and Salmonella typhosa at 170 to 250 degrees C are described. The destruction rate seems to follow the second order and can be linearized by the equation, log y = a + b . -10cx. Because c is the slope, 1/c = D3. Both a and b are constant at a given temperature and are linear functions of temperature. The D(3)170, D(3)190, D(3)210, D(3)230, and D(3)250 values for E. coli lipopolysaccharide are 251, 99.4, 33.3, 12.3, and 4.99 min, respectively, with a z value of 46.4 min. The D values for lipopolysaccharides from S. marcescens and S. typhosa are not significantly different from those from E. coli lipopolysaccharide.

Escherichia coli↗
PubMed1975

The relation between lipid mobility and the specific hormone binding of thyroid membranes.

1. The specific binding of thyroid-stimulating hormone to isolated human thyroid membranes was examined under a variety of conditions. 2. In phosphate-saline buffer (in the presence of 0.14 M-NaCl) on increasing the temperature the binding of the hormone is increased, the plots of bound/free hormone against temperature showing a distinct break around 30 degrees C. 3. Detailed analysis showed that the increased binding is associated with an increase in the number of binding sites. 4. The motional characteristics of three membrane-bound fluorescent probes, 2-(9-anthroyl)palmitic acid, 12-(9-anthryl)stearic acid and N-1-naphthyl-N-phenylamine, were also examined as a function of temperature by measuring both fluorescence polarizations and lifetimes. 5. The results indicated that the 'fluidity' of membrane lipids also increased with temperature. The temperature-dependence of this property also shows a change at about 30 degrees C. 6. Bivalent cations decreased both membrane fluidity and hormone binding. 7. Similar correlations were found between the binding of adrenocorticotrophic hormone and the fluidity of the plasma membranes obtained from adrenal-cortical cells, with the discontinuity occurring in this case at 23 degrees C. 8. The possibility of lipid mobility being important in controlling hormone-receptor function is discussed.

Anthracenes↗
PubMedDate not supplied

Differential expression of peroxidase isogenes during the early stages of infection of the tropical forage legume Stylosanthes humilis by Colletotrichum gloeosporioides.

Infection of Stylosanthes humilis by the fungal phytopathogen Colletotrichum gloeosporioides is associated with an increase in peroxidase enzyme activity within 24 h postinoculation. Peroxidase gene expression was investigated as a first step towards understanding the regulation and functional importance of this host response to fungal attack. Four distinct cDNAs Shpx 2, 5, 6, and 12, isolated from a cDNA library of S. humilis contained deduced amino acid (aa) sequence motifs characteristic of peroxidases. Three of these (Shpx 2, 5, and 6) were full-length and their deduced proteins each fell into a different homology group based on comparisons with other plant peroxidases. Each cDNA appeared to hybridize to only one or two genes in S. humilis. mRNAs corresponding to Shpx2, Shpx6, and Shpx12 were expressed relatively abundantly in young leaves, with lesser expression of Shpx2 and Shpx6 and no expression of Shpx12 detected in roots. No expression of these genes was detected in stems or old leaves. The mRNA of Shpx5 was relatively abundant in stems and to a lesser extent in young leaves. However, infection of young leaves with C. gloeosporioides greatly increased expression of the mRNAs of Shpx2 and Shpx6 but not Shpx5 nor Shpx12 compared to mock-inoculated controls. The mRNA of Shpx6 was strongly induced by the pathogen 4 h postinoculation, a time which precedes fungal penetration, while Shpx2 was induced to higher levels than controls at 24 h after inoculation. The mRNAs of both Shpx2 and Shpx6 but not Shpx5 and Shpx12 were also induced by wounding.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗