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Biomedical subjects

I Whimster

Publications and source records attributed to I Whimster.

6 recordsLinked to original sources

Surgical management of 'lymphangioma circumscriptum'.

The results of surgery in 29 patients with 'lymphangioma circumscriptum' have been reviewed 2-8 years after operation. They show that in regard to management there are two varieties: small lesions, less than 7 cm diameter, in favourable sites of the body, which are potentially curable; and large lesions, greater than 7 cm diameter on the skin with an even larger area of subcutaneous cysts, in which complete excision of all the skin and subcutaneous vesicles would require skin grafting. Nine patients had small lesions excised. Seven have had no recurrence. Twenty patients had large lesions treated by a radical excision of all or as much of the cyst bearing subcutaneous tissues and skin as possible, but leaving enough skin to permit a primary suture, even though it meant leaving skin vesicles. The lesion was controlled and the cosmetic appearance improved in 16 patients. Subsequent regression of many of the vesicles not excised supports the aetiological hypothesis of the skin lesions proposed by Whimster.

Adolescent

Pericapillary fibrin in the ulcer-bearing skin of the leg: the cause of lipodermatosclerosis and venous ulceration.

Forty-one biopsy specimens, taken from the ulcer-bearing skin of 41 legs of 21 patients attending the varicose vein clinic, were selectively stained for fibrin with phosphotungstic acid haemotoxylin before being blindly assessed,. Layers of fibrin were found surrounding the dermal capillaries in all 26 legs with lipodermatosclerosis. None of the specimens from the 15 legs with clinically normal skin contained fibrin. There was also an increased number of dermal capillaries cut in cross section per high powered field in 24 of the 26 legs with lipodermatosclerosis compared with two of the 15 legs with normal skin (p less than 0.001). The mean reduction in foot vein pressure during exercise was significantly less in the 26 limbs with pericapillary fibrin than in the other 15 limbs (p less than 10(-6). Lipodermatosclerosis is synonymous with pericapillary fibrin deposition and is associated with, and probably secondary to, both a persistently raised venous pressure and an increase in the size of the dermal capillary bed. This extravascular deposition of fibrin probably stimulates tissue fibrosis and blocks the diffusion of oxygen to the overlying epidermis, producing cellular death and venous ulceration.

Capillaries

The effect of sustained venous hypertension on the skin capillaries of the canine hind limb.

An increased number of skin capillaries has been found in human skin subjected to sustained venous hypertension. To investigate this observation, venous hypertension was produced in the hind limb of Greyhounds by fashioning an arteriovenous (AV) fistula between the femoral vessels. This caused an increase in the number of capillaries in the skin of the lower leg. The capillary permeability of normal legs and legs subjected to chronic venous hypertension was then studied by observing the movement of radioactive molecules from the plasma to the fluid within Guyton capsules. Fibrinogen, a large molecule, leaked out of the capillaries significantly faster in the limbs with a high venous pressure and an enlarged capillary bed. It is suggested that the increase in the size and permeability of the dermal skin capillaries secondary to prolonged venous hypertension is the cause of lipodermatosclerosis and venous ulceration.

Animals

The relationship between the number of capillaries in the skin of the venous ulcer-bearing area of the lower leg and the fall in foot vein pressure during exercise.

The changes in foot vein pressure during exercise have been measured in 30 normal legs and 109 legs with varicose veins or postphlebitic changes and correlated with the number of capillaries visible in a histological section of skin from the ulcer-bearing area. There was a significant correlation between the inability of the calf pump to reduce foot vein pressure during exercise and the number of capillaries in the skin. It is suggested that the increased number of capillaries secondary to venous hypertension during exercise may be the prime cause of the nutritional abnormalities that eventually cause a venous ulcer.

Adolescent