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J R Field

Publications and source records attributed to J R Field.

8 recordsLinked to original sources
PubMed1989

Equine laminitis--another hypothesis for pathogenesis.

Laminitis is an important condition in horses and ponies, not just because of the seriousness of the clinical signs and systemic changes involved, but because of the potentially poor prognosis and likelihood of recurrence. Laminitis is particularly prevalent in ponies and involves a multiplicity of aetiological factors. Fat ponies and those having previously suffered laminitis were found to be far more intolerant to oral glucose loading (1 g/kg bwt) than normal ponies or Standardbred horses. These ponies also exhibited a far greater response in plasma insulin levels after glucose loading. Insulin response tests (0.4 iu/kg bwt insulin intravenously) showed only a minimal and very protracted response in both the fat and laminitic ponies establishing the existence of an apparently innate insulin insensitivity in these animals. These findings are important in regulation of carbohydrate and lipid metabolism and play a role in the pathogenesis of laminitis. The reduction of insulin effectiveness leads to elevation in thromboxane A2 activity, predisposing the animal to peripheral vasoconstriction, compromisation of blood flow to the foot and the development of laminitis.

Animals↗
PubMed1986

Glucose tolerance and insulin sensitivity in ponies and Standardbred horses.

The existence of an innate insulin insensitivity in ponies was investigated and compared with the situation in larger breeds of horse. Ponies that were fat or had previously suffered laminitis were found to be far more intolerant to oral glucose loading (1 g/kg bodyweight [bwt]) than normal ponies or Standardbreds. These ponies also exhibited a far greater response in plasma insulin levels after glucose loading. Insulin response tests (0.4 iu/kg bwt insulin intravenously) showed only a minimal and very protracted response in both the fat and laminitic groups. The relevance of these findings in regulation of carbohydrate and lipid metabolism, and their role in the pathogenesis of hyperlipaemia, are discussed.

Animals↗
PubMed1985

Current concepts of hyperlipaemia in horses and ponies.

Hyperlipaemia is an important condition in ponies, not just because of the seriousness of the clinical signs and biochemical changes involved, but because of the distress it causes owners and breeders that have had animals suffer from it. Hyperlipaemia occurs most commonly in fat ponies in late pregnancy and is rarely seen in larger horses. The syndrome has similarities with conditions in other species but the definitive aetiologies are not yet known. The condition in ponies is undoubtedly related to stress. The biochemical mechanisms involved in equine hyperlipaemia are considered and an hypothesis of possible pathogenesis is put forward. This hypothesis is tested by presenting the results of a preliminary study to evaluate glucose and lipid metabolism in horses and ponies. It appears that the pony is markedly insensitive to insulin compared to larger horses which means that triglycerides are more readily mobilised and the animal is therefore susceptible to hyperlipaemia in a situation of negative energy balance. The effect of stress is to increase cortisol levels which only exacerbates the insulin insensitivity and so creates a vicious circle. The importance of an innate insulin insensitivity may also be important in the pathogenesis of such conditions as laminitis.

Animals↗
PubMed1970

Host resistance and survival in carcinoma of breast: a study of 104 cases of medullary carcinoma in a series of 1,411 cases of breast cancer followed for 20 years.

This paper deals with a special type of mammary carcinoma, generally of high-grade malignancy, which carries a remarkably good prognosis-the so-called "medullary carcinoma of the breast with lymphoid infiltrate." Probably the increased lymphoid tissue seen in these tumours is concerned with cell-mediated and humoral immunological reactions and reflects a strong host-defence mechanism which is responsible for the remarkably high survival rates following radical treatment. Since the evidence for host resistance to malignant disease is based largely on animal data, the opportunity to study a group of patients followed for 20 years, in whom this type of defence reaction appears to exist, is of considerable clinical interest.Among 1,411 cases of breast cancer there were 104 with medullary carcinoma (7.4%), for which the corrected 5- to 20-year survival rates have been calculated. After 20 years 74% of cases with operable medullary tumours were alive, compared with 14% of cases with similar stage non-medullary cancer. In the presence of histologically proved axillary metastases the 20-year survival rate was 61% for medullary cases, compared with only 13% for other types of breast cancer.In 30 cases of medullary cancer in which the axilla was free, the corrected 20-year survival rate was 95% following a combination of radical operation and radiotherapy. No evidence could be found that axillary dissection or postoperative irradiation is harmful to women with operable highly malignant breast cancer in whom a well-marked host resistance is thought to be present. A combination of radical mastectomy and postoperative irradiation appears to be the most effective treatment for such cases. The present grounds for rejecting a radical approach to treatment of breast cancer, based on current immunological considerations, are regarded as being quite inadequate.

Breast Neoplasms↗