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Biomedical subjects

P Belton

Publications and source records attributed to P Belton.

At least 19 recordsLinked to original sources
PubMed1996

Immunotherapy trial for horses in British Columbia with Culicoides (Diptera:Ceratopogonidae) hypersensitivity.

Immunotherapy was used to treat horses in British Columbia for Culicoides hypersensitivity. This is a severe, chronic, recurrent allergic disease of horses that results in severe irritation, large lesions, hair loss and secondary infection in the ventral midline, mane, and proximal region of the tail. A crude Culicoides extract was injected subcutaneously, in increasing doses, into 10 horses that were affected severely by the disease. Weekly doses reduced the clinical signs in 9 of the 10 horses in the 1st yr. Eight horses were treated with a maintenance dose during a 2nd yr. After the 2nd yr, 3 horses were completely free of clinical signs, 3 showed much less severe clinical signs than in untreated years, and 2 showed moderate reduction in clinical signs. Dosage, frequency of injections, and possible future applications of this technique are discussed.

Animals↗
PubMed1994

Attraction of male mosquitoes to sound.

Early observations and experiments on the attraction of male mosquitoes are reviewed briefly. Our present inadequate knowledge of the physiology of sound receptors is summarized and some of the hypotheses to explain direction finding in flying male mosquitoes are discussed. Some of the field tests carried out to attract mosquitoes to traps with sound, alone or combined with other attractants, are described and the potential for using sounds in mass trapping or sterilizing and releasing mosquitoes is assessed.

Animals↗
PubMed1993

Hypersensitivity of horses in British Columbia to extracts of native and exotic species of Culicoides (Diptera: Ceratopogonidae).

Six horses from British Columbia severely affected by Culicoides hypersensitivity, a seasonal dermatitis caused by the bites of Culicoides spp., were inoculated intradermally with extracts of six species or forms of Culicoides from British Columbia, United States, and Israel. Two native and four exotic species were thought to cause the disease in their own geographical area. The horses developed large welts within 20 min after injection of any of the six extracts, indicating an immediate (type I) reaction. The skin reactions caused by each extract peaked at or after 24 h, indicating an additional delayed (type IV) reaction. These reactions confirm that the reactions to the extracts were allergic in nature. The horses were physically irritated by each extract and developed transverse ridges in the injection area similar to those seen in natural cases of the disease, again indicating an allergic reaction. Previous studies showed that control horses injected with Culicoides extract showed only a small, short-term reaction, with no delayed component, no irritation, and no transverse ridge development, further indicating that the observed reactions were allergic in nature. The affected horses reacted to all extracts of Culicoides, despite the fact that they had not been previously exposed to most of the species, indicating that the allergen(s) was present in all the extracts tested.

Animals↗
PubMed1992

Fourier transform infrared microspectroscopy is a new way to look at plant cell walls.

Highly reproducible Fourier transform infrared (FTIR) spectra from both single onion (Allium cepa) cell walls and their constituent polymers were obtained under a variety of sampling conditions. The specificity of the chemical extraction sequence used in the preparation of the material was confirmed: pectins only are extracted by cyclohexanediaminetetraacetic acid and sodium carbonate, whereas xyloglucans are extracted by increasing concentrations of potassium hydroxide. There was very little contamination of the first potassium hydroxide extract with residual pectin. The low abundance of both phenolics and protein was also confirmed. The first sodium carbonate extraction almost completely removes esters remaining in the cell wall. We have demonstrated that FTIR spectroscopy can detect large conformational changes in pectic polymers on removal from the cell wall and on drying. FTIR spectroscopy provides a powerful and rapid assay for wall components and putative cross-links by identifying polymers and functional groups nondestructively in muro. The availability of micro-sampling and data acquisition techniques that permit subtraction of the blanket absorption of water make FTIR spectroscopy particularly suitable for studies of cell wall architecture. The use of polarizers with the microscope accessory permits determination of the orientation of particular functional groups with respect to the direction of cell elongation in carrot suspension cells.

Journal Article↗
PubMed1992

Strategic planning as used by chief executive officers.

In summary, the interviews obtained from this study suggest that CEO's in a variety of industries are attempting to "fit" their strategic planning process to their perceived environmental conditions. Indeed, management thinkers believe the biggest challenge in strategic planning will be turning CEO's into true strategic thinkers. The most successful companies, ultimately, will make strategic planning a high priority and involve all levels of management in the process. Planning becomes the unifying force that directs company actions. Hospital CEO's are obviously becoming more aware of this point as they strive to include all relevant parties (boards, physicians, etc.) in the process. Further, they seem to view planning in the classical sense, that is, as a dynamic, ever-evolving cyclical process more so than their general industry and academic contemporaries. Those hospitals that do develop strategic planning and strategic management have a definite advantage over competitors. Priorities are set and objectives are validated. This, in turn, improves productivity and creates the necessary framework for controlled growth. In addition, planning promotes teamwork and heightens motivation, bringing managers and employees together not only to meet but to exceed company goals.

Arizona↗
PubMed1991

Culicoides obsoletus (Diptera: Ceratopogonidae) as a causal agent of Culicoides hypersensitivity (sweet itch) in British Columbia.

Six horses severely affected by a seasonal dermatitis similar in both histopathology and epidemiology to Culicoides hypersensitivity (CH) and six unaffected or normal horses were inoculated intradermally with an extract of Culicoides obsoletus (Meigen), the most common Culicoides in southwestern British Columbia. Affected horses developed large welts within 20 min after injection, representing an immediate (type I) reaction; welts were largest 24 h or more after challenge, indicating in addition a delayed (type IV) reaction. This reaction was discernible for greater than 3 wk in some of the affected horses. Normal horses developed small welts which peaked 2-4 h after challenge. Affected horses were irritated by the injections and developed characteristically ridged skin at the injection sites, similar to that seen in natural lesions, whereas the normal horses showed neither discomfort nor clinical signs. C. obsoletus is one of the most numerous Culicoides species biting horses, feeds on parts of the body where lesions are found, and is, we believe, responsible for dermatitis in the Pacific Northwest. The skin test was repeated 2 yr later in three of the affected horses. In two, the reactions were similar to those in the first test, but in the third horse, the reaction was greatly reduced after the second test. This paralleled a decrease in the severity of its natural clinical signs. Thus, a skin test may be useful in the diagnosis of Culicoides hypersensitivity.

Animals↗
PubMed1991

What supervisors want to know about decentralization.

Many organizations in various industries have tended to move away from strict centralization, yet some centralization is still vital to top management. With 19 of the 22 executives interviewed favoring or implementing some form of decentralization, it is probable that traditionally centralized organizations will follow the trend and begin to decentralize their organizational structures. The incentives and advantages of decentralization are too attractive to ignore. Decentralization provides responsibility, clear objectives, accountability for results, and more efficient and effective decision making. However, one must remember that decentralization can be overextended and that centralization is still viable in certain functions. Finding the correct balance between control and autonomy is a key to decentralization. Too much control and too much autonomy are the primary reasons for decentralization failures. In today's changing, competitive environment, structures must be continuously redefined, with the goal of finding an optimal balance between centralization and decentralization. Organizations are cautioned not to seek out and install a single philosopher-king to impose unified direction, but to unify leadership goals, participation, style, and control to develop improved methods of making all responsible leaders of one mind about the organization's needs and goals.

Administrative Personnel↗
PubMed1990

Aedes togoi comes aboard.

Aedes togoi were noted as a biting nuisance on board a sailing boat anchored offshore between Vancouver Island and the Canadian mainland at the extreme north of Georgia Strait. This is the most northerly of 14 localities now known for this species in the Pacific northwest. Its distribution is mapped and briefly discussed.

Aedes↗
PubMed1984

Deterioration of axonal membranes induced by phenolic pro-oxidants. Roles of superoxide radicals and hydrogen peroxide.

The susceptibility of axons to oxidative free radicals generated by pro-oxidant neurotoxins and related compounds was tested by applying the reagents to the disheathed ventral nerve trunk of the crayfish. Electrophysiological characteristics of the axons, including spike amplitude and rise time, were recorded, using intracellular glass microelectrodes. L-Dopa, or L-dopa in the presence of copper-(bis)-histidine (Cu-his), did not change significantly the electrophysiological characteristics of the axon. A 20 mM concentration of 6-hydroxydopamine (6-OHDA), 20 mM 6-OHDA in an anaerobic environment, and 20 mM 6-OHDA with inactivated catalase-SOD accelerated the rate of decline of the spike amplitude with time to 5-8 times the control rate. Simultaneously, parallel increases in rise time and spike duration were observed, consistent with partial depolarization of the resting membrane presumably resulting from increased permeability. Catalase, superoxide dismutase (SOD), or a mixture of catalase and SOD all afforded partial protection, catalase having the least protective effect, and catalase + SOD the greatest. In contrast, 20 mM H2O2, 2 mM H2O2, or Cu-his alone did not significantly accelerate deterioration of the axon. Most of the damage results from the interaction of H2O2 with O-2, rather than from the direct action of either species. p-Hydroxyphenylpyruvate (pHPP) in the presence of Cu-his induced a similar accelerated deterioration of the axon to 4.2 times the control rate. Catalase plus SOD partially protected against this effect, but either enzyme alone was not significantly protective.

Animals↗
PubMed1983

Divergent structure activity relationships in series of enkephalin agonists and cognate antagonists.

Diallylation of the amino group of [Leu]enkephalin methyl ester yields a moderately potent, delta-selective opiate receptor antagonist. The diallyl congeners of a larger range of potent mu-and delta-selective enkephalin agonists have been prepared and were found to be weak, non-selective antagonists as assessed by their ability to antagonise the effects of normorphine and [Leu]enkephalin on the field-stimulated mouse vas deferens. Conversely, whereas [Gly3 psi (CH2S)Phe4,Leu5]enkephalin and [Gly3 psi(CH2S)-D-Phe4,Leu5]enkephalin are virtually inactive as opiate agonists the corresponding diallyl analogues are moderately potent, highly selective delta-antagonists. Analogues of diallyl[Leu]enkephalin in which the Gly2 and Gly3 residues have been replaced by D- and L- Ala have also been prepared and tested as delta-receptor antagonists. In addition, the empiric energy program ECEPP has been used to derive eighteen low energy conformations of diallyl[Leu]enkephalin and to estimate the effect of the D- and L-Ala substitutions on the conformer energies. Two conformers were identified for which there was a partial correlation between the variations in conformational energy and delta-antagonist potency.

Animals↗
PubMed1978

45Ca displacement related to pharmacologically induced prolonged action potentials in Nitella flexilis.

Nitella cells were loaded with 45Ca2+ to an activity of 2 X 10(5) cpm. Insertion of two glass-capillary electrodes into each of six cells released varying amounts of Ca2+ in the order of 1 mumol per cell, but hyperpolarizing and depolarizing pulses up to 500 ms in duration caused no measurable loss (less than 57 pmol) of Ca2+ even when the latter elicited action potentials. Addition of 10 mumol of Ba2+ or tetraethylammonium (TEA) caused losses up to 1200 pmol of Ca2+ from the cells and prolonged the action potentials by a factor of three or more. Subsequent addition of Ba2+ or TEA to treated cells caused no further losses of Ca. Because prolonged action potentials can apparently only be elicited after the chelation or displacement of Ca2+, we propose that, as in many animal cells, the K+ channels responsible for the normal brief repolarizing phase of the action potential are controlled by Ca2+ in these electrically excitable plant cells.

Action Potentials↗
PubMed1977

The effects of calcium deficiency on the electrical activity of Nitella flexilis.

Calcium chelators such as ethylenediaminetetraacetic acid and sodium citrate produce repetitive activity and prolong the spike of internodal cells of Nitella flexilis. Removal of Ca2+, Mg2+, Na+, and K+ from the outside of the cell by washing the preparation with Tris propionate or Tris chloride hyperpolarizes the cells but does not initiate repetitive activity or increase the duration of the spike appreciably. It was concluded that cell-bound Ca2+ controls the threshold for stimulation and the duration of the spike, and that the removal of Ca2+ from the cell membrane, either by chelation or displacement, changes the normal behaviour of the cell by altering its permeability to some other ion or ions.

Action Potentials↗