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Biomedical subjects

D Leach

Publications and source records attributed to D Leach.

At least 19 recordsLinked to original sources
PubMed2004

Screening of some Australian Flacourtiaceae species for in vitro antioxidant, cytotoxic and antimicrobial activity.

A total of 27 methanol extracts obtained from different plant parts of 10 species of rain forest trees belonging to four genera of the Flacourtiaceae and originating from Australia were investigated. In vitro cytotoxicity was measured by an ATP Lite-M assay method against the mouse P388 lymphocytic leukemia cell line. The total antioxidant activity has been assessed based on scavenging activity of stable ABTS free radicals. The minimum inhibition concentration (MIC) was determined by the dilution method performed in 96 well plates against four different microbes. The leaf extract of Casearia sp. (RB 3051), mature stem extract of Casearia grayi and stem extract of Scolopia braunii were found to have most antioxidant activity (IC50 = 2.9 microg/ml), cytotoxic activity (LC50 = 0.89 microg/ml) and antimicrobial activity against all four different microbes, respectively. The results obtained suggested that among the four genera studied Casearia is the most promising in respect of finding significant antioxidant, cytotoxic and also antimicrobial activity.

Animals↗
PubMed2001

Quality management and the Emergency Services Enhancement Program.

Since the introduction of the Emergency Services Enhancement Program (ESEP) in Victoria in 1995, improvements have been demonstrated in the indicators relating to Emergency waiting times, ambulance bypass rates and inpatient bed access block. This study focuses on staff perceptions of changes in these indicators, factors perceived to influence performance improvements and the extent to which ESEP is perceived to have contributed to overall patient care. A questionnaire was directed at four focus groups within each of the hospitals participating in ESEP. These were Chief Executive Officers, Emergency Department Directors and Nurse Unit Managers, bed coordinators and personnel from the Emergency Department floor. A total of 101 staff responded. Emergency Department staff were generally accurate in their perceptions of performance changes. The most important factors effecting the changes were perceived to be changes in staff profile, management of patient flow through the department, changes in administrative policies and changes in work practices. Staff perceived that patient care has improved by 10% since 1995 and that ESEP has contributed 8% of this improvement. Staff have perceived improvements in ESEP performance indicators consistent with actual changes. The possible mechanisms by which these changes have occurred are presented and discussed. Factor analysis indicated that changes perceived to be most likely to result in improvements were: changes in staff profile (seniority), managing the flow of patients through emergency departments, changing administrative policies, changes in work practices and changes in staff numbers. Improvements in patient care were considered partly due to ESEP. In addition, ESEP has raised awareness of quality management issues.

Attitude of Health Personnel↗
PubMed1999

Randomized double-blind study of the clinical duration and efficacy of Nesacaine-MPF 2% and 3% in peribulbar anesthesia.

PURPOSE: To compare 2 commercially available concentrations of Nesacaine-MPF (2-chloroprocaine) to determine the time to onset of adequate motor blockade, the quality of surgical anesthesia, and the duration of motor blockade in the extraocular muscles after peribulbar anesthesia for cataract surgery. SETTING: Tampa Eye and Specialty Surgery Center, Tampa, Florida, USA. METHODS: This double-blind, randomized, single-center study comprised 40 patients scheduled to receive peribulbar anesthesia before cataract surgery. Patients were given 5 mL of Nesacaine-MPF 2% or 3% before surgery. Beginning at the end of the injection, assessments of ocular and eyelid movement were made every 2 minutes until adequate motor blockade was achieved or 25 minutes elapsed. Ocular assessments were made immediately after completion of surgery, 60 minutes after the end of the initial injection, and at 15 minute intervals thereafter until full recovery. Assessments of the quality of anesthesia achieved by the patient during surgery were made by the surgeon. RESULTS: The 3% solution provided significantly faster onset of surgical anesthesia than the 2% solution (mean 3.9 minutes +/- 2.2 [SD] versus 6.0 +/- 3.6 minutes) (P = .02) but also required more time for recovery from anesthesia (98.9 +/- 18.7 minutes versus 84.8 +/- 20.6 minutes) (P = .02). All patients had adequate surgical anesthesia. Duration of ocular motor function was brief enough so that all patients could be sent home without an eye patch. Both concentrations were safe for use in this procedure. CONCLUSION: Both Nesacaine-MPF 2% and 3% produced safe and effective peribulbar anesthesia in all patients; however, the 3% solution provided better duration of clinical anesthesia.

Aged↗
PubMed1994

Cloning and sequencing of four structural genes for the Na(+)-translocating NADH-ubiquinone oxidoreductase of Vibrio alginolyticus.

Oligonucleotide probes based on the N-terminal amino acid sequences of the NqrA and NqrC subunits were used to clone genes for the Na(+)-dependent NADH-ubiquinone oxidoreductase complex from Vibrio alginolyticus. Four consecutive ORFs were identified encoding subunit proteins of 48.6, 46.8, 27.7 and 22.6 kDa, respectively (NqrA-D). A further ORF, showing 71% homology to the BolA protein of Escherichia coli, was located upstream. From sequence comparisons, we conclude that the Na(+)-dependent NADH-ubiquinone oxidoreductase complex of V. alginolyticus is clearly distinct from the corresponding H(+)-dependent enzymes of both prokaryotes and eukaryotes.

Amino Acid Sequence↗
PubMed1993

Recommended terminology for researchers in locomotion and biomechanics of quadrupedal animals.

This paper summarizes recommendations for terminology to be used in the description of quadrupedal locomotion and selected aspects of biomechanics. Directional terms and planes of the body (anatomical position, spatial reference systems), joint angulation, conformation, general locomotion terminology, phases of the stride and limb cycle (e.g. step, cadence) and terminology for the description of jumping are described.

Animals↗
PubMed1993

Evolutionary change in neural development within the arthropods: axonogenesis in the embryos of two crustaceans.

It has been previously suggested that there is a conservative program for neural development amongst the arthropods, on the basis that a stereotyped set of cells involved in establishing the axon tracts in the CNS of insect embryos is also present in crayfish embryos. We have examined the spatiotemporal pattern of axon growth from a set of early differentiating central neurons in the embryo of two crustaceans, the woodlouse Porcellio scaber and the freshwater crayfish Cherax destructor, and drawn comparisons with insect neurons whose somata lie in corresponding positions within the CNS. While many of the woodlouse and crayfish neurons show a similar pattern of axon growth to their insect counterparts, the axon trajectories taken by others differ from those seen in insects. We conclude that this aspect of early neural development has not been rigidly conserved during the evolution of the crustaceans and insects. However, the extent of similarity between the insects and the crustaceans is consistent with the idea that these groups of arthropods share a common evolutionary 'Bauplan' for the construction of their nervous systems. While the pattern of early axon growth in the woodlouse and crayfish embryos is sufficiently similar that many neurons could be confidently recognised as homologues, several differences were noted in both the relative order of axon outgrowth and axon morphologies of individual neurons.

Animals↗
PubMed1991

Applications of chemical-shift-selective NMR microscopy to the non-invasive histochemistry of plant materials.

Chemical-shift-selective imaging at microscopic resolution has been applied to the study of various plant materials including orange peel, grape berries and both dried and undried fruits of fennel. It is shown that selective imaging of aromatics and carbohydrates as well as water and oil can be performed with in-plane resolution down to 13 microns and slice thicknesses of 1 mm or less, at a field strength of 4.7 Tesla. The noninvasive nature of the method gives it advantages over established methods of plant histochemistry which involve sectioning and staining to reveal different chemical constituents.

Fruit↗
PubMed1990

Action of a transposable element in coding sequence fusions.

The original Casadaban technique for isolating fused cistrons encoding hybrid beta-galactosidase proteins used a Mucts62 prophage to align the upstream coding sequence and lacZ prior to selection. Kinetic analysis of araB-lacZ fusion colony emergence indicated that the required DNA rearrangements were regulated and responsive to conditions on selection plates. This has been cited as an example of "directed mutation." Here we show genetically that the MuA and integration host factor (IHF) transposition functions are involved in the formation of hybrid araB-lacZ cistrons and propose a molecular model for how fusions can form from the initial strand-transfer complex. These results confirm earlier indications of direct Mu involvement in the fusion process. The proposed model explains how rearranged Mu sequences come to be found as interdomain linkers in certain hybrid cistrons and indicates that the fusion process involves a spatially and temporally coordinated sequence of biochemical reactions.

Base Sequence↗
PubMed1987

Genome interactions which influence DNA palindrome mediated instability and inviability in Escherichia coli.

The interaction of three factors determine the detrimental effect of a palindromic DNA sequence in Escherichia coli cells. The first is the nature of the palindrome (its length, extent of central asymmetry and perhaps its base sequence), the second is the genotype of the host cell and the third is the replicon within which it is located. In this paper we extend the genetic and physical characterization of lambda bacteriophages carrying a palindrome of approximately 560 base pairs. We also show that a palindrome of approximately 110 base pairs which can be cloned in a plasmid cannot be cloned in a phage M13 derivative. These observations are relevant to the choice of vectors used in the cloning of eukaryotic DNA containing palindromic sequences.

Bacteriophage lambda↗
PubMed1986

In vivo loss of supercoiled DNA carrying a palindromic sequence.

Interest in the fate of long palindromic DNA sequences in E. coli has been kindled by the observation that their inviability is overcome in recBC sbcB strains and that these hosts permit the construction of DNA libraries containing long palindromic sequences present in the human genome. In this paper we show that a reduction in the level of intracellular supercoiled DNA occurs as the result of the presence of a 530 bp palindrome in bacteriophage lambda. This reduction occurs in Rec+ and recA strains but not in strains lacking exonucleases V and I (recBC sbcB). However, the DNA must be active (not repressed) for this reduction to be observed, since it is not seen in a Rec+ host lysogenic for phage lambda. These results argue against two hypotheses: firstly, that the palindrome causes inviability solely by interfering with packaging, and secondly, that it does so solely by interfering with recombination. Conversely, these results suggest that a feature of active monomeric DNA (probably its replication) is involved in inviability.

Bacteriophage lambda↗
PubMed1986

Relationships between stride length, stride frequency, velocity, and morphometrics of foals.

Velocity-dependent changes in stride length and frequency were studied in 19 male foals, 6 to 8 months of age, and were related to body morphometrics. Eighteen distance and 8 angle measurements were digitized from 16-mm films of standing foals. The total mass and the percentage of total mass acting through the forelimbs were also recorded. Stride length and frequency data were extracted from 16-mm films of 239 strides of the walk, trot, and canter-gallop. Polynomial-regression analysis was used to determine the equation that best described the relationship between data of stride length or frequency vs velocity and stride length vs stride frequency for each foal, for the total population, and for the walk, trot, and canter-gallop data from the total population. Stepwise-regression analysis was done of stride length, or slope of the stride length-velocity line (frequency-1) vs distance, angle, and mass measurements. The stride length for each foal was calculated for a stride frequency of 2 strides/s. The maximum recorded velocity was 11.45 m/s. There was overlap in the velocity ranges at which gaits were used: the walk or trot were used at velocities between 1.7 to 2.0 m/s and a trot or canter were used over a wider velocity range of 3.2 to 5.8 m/s. Stride length did not exceed 4.72 m. The mean stride length at a frequency of 2 strides/s was 2.57 m and was significantly (P less than 0.05) correlated to total mass (r = 0.6335) and length of the metacarpus (r = -0.5115), but not to wither height.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗