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Biomedical subjects

S A May

Publications and source records attributed to S A May.

At least 73 records · Page 4Linked to original sources
PubMed1987

Cellular aspects of inflammation. The Ciba-Geigy Prize for Research in Animal Health.

The migration of leucocytes to sites of acute and chronic inflammation is an event of central importance to the maintenance of inflammatory processes; extravascular leucocytes are responsible for generating chemical mediators of inflammation and the phagocytosis of particulate matter. They may also be involved in the conversion of acute to chronic inflammatory lesions. Leucocytes are attracted to sites of tissue injury by a range of chemoattractants. This paper describes the development of a method for separating on Percoll gradients purified populations of equine polymorphonuclear and mononuclear leucocytes and use of the isolated cells in vitro studies. Two independent assay methods, the agarose microdroplet and the Boyden chamber microfilter techniques, were used. The assays were utilised in three ways: (a) to investigate the sensitivity of polymorphonuclear and mononuclear leucocytes to two standard chemoattractants, zymosan activated plasma and n-formyl-methionyl-leucyl phenylalanine; (b) to study the chemoattractant properties of leukotriene B4 and prostaglandin E2 for equine leucocytes; and (c) to investigate the inhibitory actions of several nonsteroidal anti-inflammatory drugs (NSAIDs) on equine leucocyte movement.

Acute Disease↗
PubMed1987

Modulation of lymphocyte activating factor activity (interleukin 1 like activity) and acute phase proteins in pertussis-induced air pouch inflammation by muramyl dipeptide.

We have studied the effect of the macrophage activator, muramyl dipeptide (MDP) on immune inflammation induced in the rat six day subcutaneous air pouch. Treated animals received either 100 micrograms or 200 micrograms MDP at the time of challenge and twenty four hours before exudate harvest. Using the thymocyte co-mitogenic assay for lymphocyte activating factor (LAF), 100 micrograms MDP enhanced LAF activity whereas 200 micrograms caused inhibition. Increased dilution of 200 micrograms exudate in this assay removed this inhibition. Similarly, at the lower dose, MDP caused enhanced production of the acute phase protein alpha 1 glycoprotein, whereas the higher dose had no effect. The present study suggests that macrophage activity can be manipulated in vivo to produce LAF and naturally occurring inhibitors of LAF. These studies indicate that the stimulation of LAF inhibitors by MDP may be a potential therapeutic action.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

Identification of hindleg lameness.

The use of markers placed over the tuber coxae on each side of a horse to aid identification of the relative movement of these structures at the trot, for teaching and research purposes, is described. In each case of hindleg lameness studied, the tuber coxae on the lame side showed a consistent increase in vertical displacement relative to that of the contralateral limb, and a characteristic pattern of movement throughout the stride irrespective of the site or cause of pain.

Animals↗
PubMed1987

Contrast radiography in the investigation of sinus tracts and abscess cavities in the horse.

Contrast radiography is a valuable technique in the investigation of infected foci in the horse. Its simplest form, a metal probe, will demonstrate the direction and, in the case of a short tract, the extent of the lesion. However, liquid contrast agents often give more information by following the course of long, tortuous sinus tracts, accurately delineating the boundaries of lesions and identifying the presence of foreign bodies.

Abscess↗
PubMed1986

Surgical arthrodesis for the treatment of osteoarthrosis of the proximal intertarsal, distal intertarsal and tarsometatarsal joints in 30 horses: a comparison of four different techniques.

Over a period of seven years, 30 horses were treated by surgical arthrodesis for lameness resulting from osteoarthrosis of the proximal intertarsal, distal intertarsal and tarsometatarsal joints (bone and occult spavin). Twenty-five horses were affected in one hock only and five were affected bilaterally. Four different techniques for achieving arthrodesis were used. Fourteen out of 18 horses (78 per cent) with involvement of the distal intertarsal and tarsometatarsal joints only and six out of 11 horses (55 per cent) in which the proximal intertarsal joint was also involved became sound following surgery. The status of one other horse, with involvement of the proximal intertarsal joint, is not known.

Animals↗
PubMed1986

Iopamidol myelography in the horse.

The use of the non-ionic, water-soluble contrast agent iopamidol for myelography in seven horses is described. Contrast columns of diagnostic quality were produced in all seven cases and the procedure did not invoke any adverse reactions in the five cases which were recovered from general anaesthesia. It is concluded that iopamidol is a safe and effective contrast agent for myelography in the horse.

Animals↗
PubMed1985

Case of quadrilateral flexural contracture in a 10-year-old pony.

The management of a case of quadrilateral flexural contracture in a 10-year-old pony is described. The animal was restored to normal appearance and function through a combination of surgical desmotomy and management techniques; the importance of analgesia and exercise as adjuncts to surgery is emphasised. The aetiology and pathogenesis of the condition in the immature animal and the adult is compared and a possible association is made between this condition and palmar fibromatosis (Dupuytren's contracture) occurring in man.

Anesthesia, General↗
PubMed1985

Converging adrenergic and cholinergic mechanisms in the inhibition of Cl secretion in fish opercular epithelium.

The rate of Cl secretion (Isc) by the opercular epithelium of Fundulus heteroclitus is stimulated by elevations in cyclic AMP (cAMP) levels elicited via beta 1-adrenergic receptor activation, and inhibited by both alpha 2-adrenergic and muscarinic cholinergic receptor activation via mechanisms presently unknown. A comparison of these two inhibitory responses was made using clonidine, an alpha 2-adrenergic agonist, and acetylcholine (ACh), a cholinergic agonist. The dose required for maximum inhibition was 100 times greater for ACh, but in all other respects the responses elicited by both agonists were statistically indistinguishable. Adrenergic antagonists did not diminish the ACh inhibition, and cholinergic antagonists did not diminish the clonidine inhibition, indicating that the two receptor types were distinct from each other. In control tissues and tissues pretreated with agents that increase cAMP levels (isoproterenol, IBMX, forskolin), both ACh and clonidine had no effects on cyclic AMP levels, indicating an inhibitory mechanism independent of adenylate cyclase. Neither Ca-free media nor a variety of calcium antagonists diminished the ACh or clonidine inhibitions. These results suggest that the alpha 2-adrenergic and muscarinic cholinergic pathways converge into a common pathway to inhibit Cl secretion by a mechanism not involving adenylate cyclase or the mobilization of either extracellular or intracellular calcium stores.

Acetylcholine↗
PubMed1984

cAMP-mediated regulation of chloride secretion by the opercular epithelium.

Catecholamine regulation of the Cl- secretion rate (short-circuit current, Isc) and adenosine 3',5'-cyclic monophosphate (cAMP) levels of the opercular epithelium was investigated by using 3-isobutyl-1-methylxanthine (IBMX), forskolin, and adrenergic agonists. In this tissue alpha-adrenergic agonists inhibit, and beta-adrenergic agonists stimulate, the Isc (J. Physiol. London 294: 483-495, 1979). IBMX and forskolin stimulated the Isc 125 and 85%, respectively, and simultaneously produced 2.5- and 70.0-fold elevations in the cAMP levels, respectively. These findings confirm previous observations demonstrating that stimulation of the Isc in this tissue is mediated by elevations in cAMP (J. Comp. Physiol. B 145: 29-35, 1981). Isoproterenol, a beta-agonist, had no effect on the Isc of either IBMX- or forskolin-stimulated tissues but increased the cAMP level an additional 5.8-fold in IBMX-stimulated tissues. Clonidine, an alpha-agonist, inhibited the Isc in IBMX-stimulated tissues only and had no effect on cAMP levels in either IBMX- or forskolin-stimulated tissues. These findings demonstrate that catecholamine-induced inhibition of the Isc can occur while the cAMP level remains elevated, indicating that this effect is not mediated by lowering cAMP levels. This observation is strong evidence for a cAMP-independent mechanism for catecholamine-induced inhibition of Cl- secretion in the opercular and similar epithelia.

1-Methyl-3-isobutylxanthine↗