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S J Livingston

Publications and source records attributed to S J Livingston.

5 recordsLinked to original sources
PubMed2005

Amendment effects on soil test phosphorus.

Applications of animal manures have increased soil test P values in many parts of the USA and thus increased the risk that soil P will be transferred to surface water and decrease water quality. To continue farming these areas, landowners need tools to reduce the risk of P losses. A field experiment was conducted near Kurten, TX, on a Zulch fine sandy loam (thermic Udertic Paleustalfs) with Bray-1 P values exceeding 3000 mg P kg(-1) soil (dry wt.) in the A(p) horizon to evaluate the effectiveness of soil amendments for reducing soil test P values. Soils were amended annually from 1999 to 2001 with 1.5 and 5.0 Mg gypsum ha(-1), 1.4 Mg alum ha(-1), or 24.4 Mg ha(-1) of waste paper product high in Al alone or in combination with 1.5 Mg gypsum ha(-1) and/or 1.4 Mg alum ha(-1). These treatments supplied a maximum of 225 and 1163 kg ha(-1) yr(-1) of Al and Ca, respectively. Soil Bray-1 P and dissolved reactive P levels were monitored from 1999 to 2004. None of the soil amendment treatments affected Bray-1 P values. Only annual additions of 5.0 Mg gypsum ha(-1) from 1999 to 2001 significantly reduced soil dissolved reactive P. Dissolved reactive P levels reached minimal levels after two applications of 5.0 Mg gypsum ha(-1) but increased in 2003 and 2004. These results indicate that soil dissolved reactive P levels can be reduced if sufficient amounts of gypsum were added to supply Ca in amounts similar to the soil test P values.

Agriculture↗
PubMed1992

Novel inhibitors of enkephalin-degrading enzymes. IV: Structure-activity relationships within the penicillins as enkephalinase inhibitors.

A range of penicillins have been examined as competitive reversible inhibitors of enkephalinase (neutral endopeptidase; EC 3.4.24.11). Carfecillin (Ki = 0.18 microM) was the most potent inhibitor in the series, whereas cloxacillin (27.5 microM), ampicillin (41.0 microM), nafcillin (58.7 microM) and carbenicillin (158 microM) had moderate potency and benzyl penicillin (885 microM), mezlocillin (473 microM) and azlocillin (556 microM) were weak inhibitors. Structure-activity relationships within the series have been rationalised from a consideration of molecular graphics analysis of the match between receptor binding groups with thiorphan as well as log P values.

Computer Graphics↗
PubMed1988

Amelioration of naloxone-precipitated opioid withdrawal symptoms by peripheral administration of the enkephalinase inhibitor acetorphan.

The effects of 60 min pretreatment with the enkephalinase inhibitor acetorphan were assessed on naloxone-precipitated (2.5 mg/kg IP) abstinence in chronically morphinized rats. In addition, the antinociceptive activity of the compound was investigated in mice. Intraperitoneal injection (50 mg/kg) in rats attenuated some aspects of the opioid withdrawal syndrome such as burrowing, wet dog shakes, squeal on touch hostility, tachypnoea, ptosis and rough hair, whereas jumping and escape behaviour were significantly increased in acetorphan-treated animals. No effect was observed on withdrawal hypothermia or acute weight loss. Similarly, chronic dosing with acetorphan after withdrawal produced no significant effect on body weight. Acetorphan (50 mg/kg IP) failed to produce any antinociceptive activity in the mouse tail immersion test, but potentiated the antinociceptive effect of D-Ala2-D-Leu5-enkephalin. These results are discussed in terms of acetorphan crossing the blood-brain barrier before being hydrolysed to thiorphan, thus yielding opioid withdrawal relieving effects.

Amino Acids, Sulfur↗
PubMed1978

New medium for selection and presumptive identification of the Bacteroides fragilis group.

A medium, Bacteroides fragilis bile-esculin (BBE) agar, was designed for the selection and, presumptive identification of the B. fragilis group. BBE agar contains bile, esculin, ferric ammonium citrate, hemin, and gentamicin in a Trypticase soy agar base. Growth in the presence of 20% bile and esculin hydrolysis, detected by blackening of the medium, provide presumptive evidence for the identification of the B. fragilis group. In addition to stimulating the growth of many strains of the B. fragilis group, hemin provides the option of testing isolates for catalase production. Gentamicin and bile prevent the growth of most organisms other than the esculin-positive bacteroides that can tolerate bile. Of 160 clinical isolates of the B. fragilis group tested on BBE agar, 159 grew well on the medium and 157 blackened it. Other anaerobes, Enterobacteriaceae, and enterococci either failed to grow on BBE agar or did not produce the characteristic morphology and blackening associated with isolates of the B. fragilis group. In a clinical laboratory trial, 687 specimens from patients were inoculated onto BBE agar plates. The B. fragilis group was recovered from 81 (11.8%) of these specimens in 24 to 48 h. Use of BBE agar in the clinical laboratory enables earlier recovery and identification of this important pathogen.

Anaerobiosis↗