Search PubMed⌕ Search

Biomedical subjects

C D Fletcher

Publications and source records attributed to C D Fletcher.

At least 289 records · Page 16Linked to original sources
PubMed1988

Experimental microvascular autogenous vein grafts for arterial defects: II. A histopathologic study of the grafts.

Twelve autogenous vein grafts, of average diameter 1.5 mm, which had been used to bridge defects in the contralateral femoral artery of adult rabbits by a minimally traumatic technique, were examined over a 12-week postoperative period. Each graft remained widely patent but showed fibroelastic intimal thickening with time. Further evidence of arterialisation was the development of a prominent subintimal layer of smooth muscle. Also noted was the presence of medial fibrosis, with both calcification and ossification. This latter is suggestive of damage due to disruption of the vasa vasorum. It would appear that arterialisation of microvascular vein grafts occurs independently of surgical trauma and is therefore difficult to avoid. However, these pathologic changes were not as severe, nor was there as much luminal narrowing, as at the previously described anastomotic sites. The most important cause of these changes appears to be arterial pressure.

Animals↗
PubMed1988

Effects of conjugated equine oestrogens with and without the addition of cyclical norgestrel on serum and urine electrolytes, and the biochemical indices of bone metabolism and liver function.

Serum and urine electrolytes, and biochemical indices of bone metabolism and liver function were measured in 51 post-menopausal women treated with two hormone replacement therapy regimens for 24 wk. Twenty-six of the women were treated continuously with conjugated equine oestrogens (0.625 mg/day) and the remainder were treated as above with the addition of norgestrel (0.15 mg/day) during the last 12 days of each 28-day cycle. Both treatment regimens affected electrolytes in a similar manner. The most consistent effect was a reduction in serum sodium levels and a reduction in urinary sodium/creatinine ratios. The combined regimen appeared to have a greater effect on sodium reabsorption. Both regimens decreased all the biochemical indices of bone metabolism measured, viz serum calcium (corrected for albumin), phosphate and alkaline phosphatase and urinary calcium/creatinine and hydroxyproline/creatinine ratios. The preparations used decreased the parameters by similar amounts over the 24 wk indicating that both were equally effective in reducing bone turnover. The data suggested, however, that the combined regimen had a more profound effect on bone metabolism during the early phase of treatment. The two treatment regimens had broadly the same effects on the biochemical indices of liver function, reducing albumin levels and all the liver enzymes. Judging by these indices neither regimen had a deleterious effect on liver function. We conclude that the two hormone replacement regimens have similar effects on the biochemical indices measured, but there are subtle differences between the two treatments which merit further research.

Bone and Bones↗
PubMed1988

Fibrous hamartoma of infancy: a histochemical and immunohistochemical study.

Fibrous hamartoma of infancy is an uncommon lesion, the histogenesis and biological nature of which are uncertain. Ten cases have been studied by light microscopy, mucin histochemistry and immunohistochemistry. The typical histological features are presented. The presence of hyaluronic acid and of chondroitin-4- and -6-sulphate and keratan sulphate has been demonstrated in different components of the tumour. Vimentin positivity was noted in the undifferentiated and fibroblastic components. The implications of these findings are discussed. Whether the lesion merits the designation of hamartoma or is, in fact, a benign neoplasm remains obscure.

Child↗
PubMed1988

Intramuscular and intermuscular lipoma: neglected diagnoses.

Fifty-four cases of lipoma arising either within or between skeletal muscles are presented. Of these, 52 were identified in a systematic review of 2478 tumours of adipose tissue diagnosed and treated in one hospital over a 25 year period. Intramuscular lipomas account for 1.8% of fatty tumours, arise predominantly in middle to late adult life and, in our series, are commonest on the trunk. They may be divided into infiltrative and well-circumscribed types, respective local recurrence rates being 19 and 0%. Intermuscular lipomas are comparatively rare, 0.3% of fatty tumours, have a similar age distribution and arise most often in the anterior abdominal wall; none of the seven cases recurred. It is important that both pathologists and surgeons appreciate the significant tendency of infiltrative intramuscular lipomas to recur. Hence, preventative surgical measures may be undertaken and worries that the lesion may be sarcomatous can be avoided. Differential diagnosis, most importantly from well-differentiated liposarcoma, is discussed.

Female↗
PubMed1988

Pigmented neuroectodermal tumour of infancy: an immunohistochemical study.

The pigmented neuroectodermal tumour of infancy is a rare neoplasm of uncertain histogenesis which, in the majority of cases, arises in the maxilla and pursues a benign course. Currently, it would be classified in the group of peripheral primitive neuroectodermal tumours. Histologically it is composed of two principal cell types: neuroblast-like and melanocyte-like. Three typical cases are presented herein, which appear to be the first examined with a panel of antibodies. The neuroblast-like cells labelled positively for neurone-specific enolase but were negative for S-100, neurofilaments, glial fibrillary acidic protein, vimentin, cytokeratin, epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA). The melanocyte-like cells stained positively for neurone-specific enolase, vimentin and cytokeratin but were negative for S-100, neurofilaments, glial fibrillary acidic protein, EMA and CEA. The significance of these findings is discussed in the light of previous suggestions about the differentiation that these tumours show.

Cell Differentiation↗
PubMed1988

Giant cell fibroblastoma of soft tissue: a clinicopathological and immunohistochemical study.

Giant cell fibroblastoma is an uncommon, benign tumour of soft tissue which was first described in 1982. Thirty-five cases have been previously published. Six new cases are reported herein, which have also been examined immunohistochemically for the expression of vimentin, desmin, myoglobin, S-100 protein, neurofilaments, Factor VIII related antigen and binding of the lectin Ulex europaeus. The previous literature has been reviewed. Giant cell fibroblastoma most often presents in early childhood as a slowly growing, infiltrative subcutaneous mass at a wide variety of sites. It shows a predilection for males and may recur locally in up to 50% of cases. The very distinctive histological features, characterized by so-called solid and angiectoid areas, are presented. The tumour cells were vimentin positive but negative for all other markers used. In particular, there was no evidence of endothelial differentiation. The histogenesis of this unusual tumour is discussed in the light of previous ultrastructural findings.

Adolescent↗
PubMed1988

Pigmented dermatofibrosarcoma protuberans (Bednar tumour): melanocytic colonization or neuroectodermal differentiation? A clinicopathological and immunohistochemical study.

Approximately 5% of cases of dermatofibrosarcoma protuberans contain dendritic melanocytes; such lesions are often known as Bednar tumours. These neoplasms have received little attention in the literature but seem to show no great clinicopathological differences from conventional dermatofibrosarcoma protuberans except for the presence of melanocytes. The existence of such tumours, combined with ultrastructural evidence, has led some leading authors to regard them all as being of neuroectodermal origin. Seven examples of the pigmented variant are presented herein, of which six have been studied immunohistochemically and one has been examined ultrastructurally. Except for the presence of melanocytes in each tumour, no evidence of neuroectodermal (in particular perineural fibroblastic) differentiation has been demonstrated. The histogenesis of dermatofibrosarcoma protuberans and its pigmented variant is discussed. The possibility that the pigmentation may simply reflect secondary melanocyte colonization from the epidermis should be considered.

Adolescent↗
PubMed1988

The effects of conjugated equine estrogens plus cyclical dydrogesterone on serum lipoproteins and apoproteins in postmenopausal women.

Serum lipoprotein and apoprotein concentrations were monitored for 24 weeks in 26 postmenopausal women treated with conjugated equine estrogens (0.625 mg/day) with the addition of dydrogesterone (10 mg/day) for the last 12 days of each 28 day cycle. The women had had no previous hormone replacement therapy. The estrogen plus dydrogesterone regimen caused significant (P less than 0.05) increases in triacylglycerol and HDL cholesterol concentrations. Both HDL2 and HDL3 cholesterol were increased. There were no other significant changes in lipoprotein concentrations. Both apoprotein AI and apoprotein AII concentrations increased significantly (P less than 0.05) over the study period. The ratios of apoprotein AI to apoprotein AII, apoprotein AI to HDL cholesterol and apoprotein AII to HDL cholesterol did not change. At the doses employed in this study, the use of dydrogesterone as a progestogen alters the effects of conjugated equine estrogens on lipoproteins and reinforces the view that the effects of a combined HRT regimen cannot be predicted from a consideration of the effects of the individual components.

Apoproteins↗
PubMed1988

Cartilaginous tumours of soft tissue.

Tumours of soft tissue may manifest cartilaginous differentiation as a primary phenomenon (as in chondromas or extraskeletal myxoid and mesenchymal chondrosarcomas) or as a secondary metaplastic feature (most notably in extraskeletal osteosarcomas or malignant nerve sheath tumours). The literature regarding primary cartilaginous tumours is reviewed and their differential diagnosis discussed. Soft tissue chondromas are noteworthy for their tendency to show significant nuclear pleomorphism. Extraskeletal chondrosarcoma is much rarer than its osseous counterpart, accounting for only 1-2% of soft tissue sarcomas. Virtually all such sarcomas can be classified into the myxoid or mesenchymal subtypes, of which myxoid carries a better prognosis. Soft tissue neoplasms which may show focal cartilaginous metaplasia are covered more briefly.

Cartilage↗
PubMed1987

Experimental microvascular autogenous vein grafts for arterial defects: a study of anastomotic sites.

Autogenous femoral vein grafts with an average external diameter of 1.5 mm and an average length of 2.87 cm have been used to bridge defects in the contralateral femoral artery of 15 adult New Zealand white rabbits. An experimental microvascular technique to minimise trauma to the graft was performed, by which clamps were never applied to the graft itself. Patency was assessed over a 12-week period, and the overall graft success rate, excluding one technical failure, was 86%. Each of the three failures resulted from thrombosis. Histologic examination of the patent anastomoses showed marked medial damage at 1 week, complicated by fibrosis and calcification by 4 weeks; thereafter the intima developed prominent fibroelastic thickening. This led to a degree of luminal narrowing by 12 weeks. However, the underlying medial damage, attributable to operative trauma, did not seem to diminish luminal patency.

Animals↗
PubMed1987

A comparison of the effects of lipoproteins of two progestogens used during cyclical hormone replacement therapy.

Lipoprotein levels were measured in 11 women who had been treated with 0.625 mg/day conjugated equine oestrogens with the addition of 0.15 mg/day DL-norgestrel for the last 12 days of each 28 day cycle for 48 wk. Treatment was then changed to an identical oestrogen regimen with dydrogesterone, 10 mg/day, as progestogen and monitoring continued for a further 24 wk. The oestrogen plus norgestrel regimen caused a significant reduction in low density lipoprotein (LDL) cholesterol levels. During the 24 wk after the change of therapy, levels of high density lipoprotein (HDL) increased significantly due to an increase in the HDL2 fraction and there was an upward trend in LDL cholesterol which did not attain statistical significance. We conclude that, when used in combination with conjugated equine oestrogens, changing from norgestrel, 0.15 mg/day, to dydrogesterone, 10 mg/day, does not lead to any significant improvement in lipoprotein profile.

Cholesterol, LDL↗
PubMed1987

Spindle cell lipoma: a clinicopathological study with some original observations.

Forty-one cases of spindle cell lipoma, an entity first described in 1975, are presented. Of these, 38 were identified in a systematic review of 2478 tumours of adipose tissue diagnosed and treated in one hospital over a 25 year period. This lesion, therefore, accounts for about 1.5% of adipocytic neoplasms and is outnumbered by conventional benign lipomas by approximately 60 to 1. The remaining three were referred cases. Seventy-five per cent of the lesions arose, as expected, on the back of the neck, upper back or shoulder, almost exclusively in males between 40 and 70 years of age. Ten lesions were identified at unusual sites: six in the limbs, three on the face and one on the trunk. One lesion arose within skeletal muscle, a previously unreported phenomenon, and this case showed both cartilaginous and osseous metaplasia. Only one of the 41 tumours has recurred locally. The range of histological features in spindle cell lipoma is described and the differential diagnosis is discussed.

Adipose Tissue↗
PubMed1987

Cellular schwannoma: a distinct pseudosarcomatous entity.

Eighteen cases of cellular schwannoma, a recently delineated benign entity, are described. These tumours present most often in middle-aged adults of either sex and show a predilection for the paravertebral region of the mediastinum and retroperitoneum. More than half the tumours macroscopically arose from a nerve but none was associated with von Recklinghausen's disease. The light microscopic features are remarkably consistent but are not immediately recognizable as neural in type. Means of distinction from a malignant nerve sheath tumour and from a variety of other soft tissue tumours are discussed. Immunohistochemical positivity for S-100 protein has been demonstrated in 17 of the 18 cases. Prolonged follow-up has revealed local recurrence in only one case; none has metastasized.

Adolescent↗
PubMed1987

Infantile myofibromatosis: a light microscopic, histochemical and immunohistochemical study suggesting true smooth muscle differentiation.

Eight cases of infantile myofibromatosis, a rare, sometimes multicentric neoplasm which shows an inherited tendency, have been studied by light microscopy, conventional histochemistry and immunohistochemistry. This tumour is commonest in early infancy and may arise at a wide variety of sites, most often in subcutaneous tissue. Evidence is presented that this entity shows true smooth muscle differentiation, rather than it being of a myofibroblastic nature and hence its current name may be incorrect. In this context, the presence of desmin positivity in six out of eight cases is of particular importance. The differential diagnosis is discussed.

Adolescent↗
PubMed1987

Soft tissue sarcomas apparently arising in chronic tropical ulcers.

Of 720 soft tissue sarcomas received from Malawi over a 15 year period, eight had apparently arisen in chronic tropical ulcers which are endemic in that part of Africa. These eight tumours were classified as leiomyosarcoma (three), extraskeletal osteosarcoma (two), malignant fibrous histiocytoma (one), myxoid liposarcoma (one) and unclassifiable (one). All had a history suggestive of malignant change in a long-standing ulcer, in each case clinically thought to be a squamous carcinoma. However, in none was there evidence of an epithelial origin and all were negative for epithelial membrane antigen and cytokeratin. This association has not previously been reported. The validity of this proposed association is discussed.

Adult↗