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C J Randall

Publications and source records attributed to C J Randall.

10 recordsLinked to original sources
PubMed1992

Independent pathways regulate the cytosolic [Ca2+] initial transient and subsequent oscillations in individual cultured arterial smooth muscle cells responding to extracellular ATP.

Stimulation with extracellular ATP causes a rapid initial transient rise followed by asynchronous periodic oscillations in cytosolic calcium ion activity ([Ca2+]i) in individual aortic smooth muscle cells in either HEPES-buffered or HCO3(-)-buffered saline. The dose at which one-half of the cells display an initial rise in cytosolic calcium is 0.11 microM ATP in the presence of external Ca2+ and 0.88 microM ATP in the absence of external Ca2+; the corresponding value for oscillations in the presence of external Ca2+ is 2.6 microM ATP. While the initial transient displays rapid desensitization, the oscillations persist for greater than 30 min in the continuous presence of ATP. The presence of the agonist ATP is also absolutely required for the maintenance of the oscillations, presumably to provide continuous activation of P2 purinoceptors. The average frequency of oscillation is approximately 0.9 min-1. The frequency depends only slightly on the concentration of ATP, and oscillations do not collapse into a prolonged elevated [Ca2+]i at high concentrations of ATP. Both Ca2+ influx and release from internal stores participate in the initial transient. Oscillations are not produced in the absence of external Ca2+ but are initiated upon the addition of external Ca2+ in the continued presence of ATP. Oscillations in progress are abolished by the removal of extracellular Ca2+ with one additional peak occurring after the Ca2+ removal. These data suggest that extracellular Ca2+ influx is required for the maintenance of the posttransient oscillations, presumably to provide the Ca2+ necessary for refilling intracellular Ca2+ pools that are the source of the oscillating [Ca2+]i. The Ca2+ influx is not regulated by voltage-gated Ca2+ channels. The data in this report are consistent with the view that the initial transient has contributions from two receptor-mediated pathways, and the oscillations are controlled either by a mechanism separate from the ones that control the initial transient or by steps whose control diverges before the point of desensitization.

Actins↗
PubMed1989

Observations on swollen head syndrome in broiler and broiler breeder chickens.

Chickens on 14 broiler breeder farms were examined at various times throughout their laying cycle. Antibodies to the turkey rhinotracheitis virus were common although they were not always accompanied by clinical signs of the swollen head syndrome. Ninety-nine broiler flocks were tested of which only 20 were serologically positive to the virus. Some of these infections were subclinical. On nine farms where swollen head syndrome occurred several successive flocks were sampled; the syndrome occurred intermittently.

Animals↗
PubMed1989

Dysphagia after fast neutron therapy to the head and neck.

Nine patients presenting with dysphagia following successful treatment for head and neck cancer with neutron radiotherapy are reviewed. Combined clinical and videofluoroscopic investigation is used to analyse their deficits and provide indications for management. All patients show impairment of both the oral and pharyngeal phases of the swallow, with the exception of one subject who shows signs of focal neurological damage. It is suggested that fibrosis is the underlying cause of dysphagia in the remainder.

Adult↗
PubMed1988

Avulsion of the patellar ligament in osteopenic laying fowl.

Metabolic bone disease in laying fowl has been associated with mortality and decreases in egg production. Recently there appears to have been an increasing incidence of the disease and the affected flocks have shown a variable response to dietary treatments. In 14 birds from eight recent submissions, avulsion of the patellar ligament together with part of its bony insertion was observed. Because the skeletons of the affected birds were judged from radiographs to be osteopenic, the lesions were probably pathological fractures. Histopathological studies of four birds revealed osteoporosis affecting cancellous bone trabeculae; in one bird, however, the medullary bone trabeculae were largely composed of unmineralized or poorly mineralised matrix, a finding which can be interpreted as osteomalacia.

Animals↗