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Biomedical subjects

P D Coleridge-Smith

Publications and source records attributed to P D Coleridge-Smith.

12 recordsLinked to original sources
PubMed1998

Increased plasma vascular endothelial growth factor among patients with chronic venous disease.

Skin damage in the presence of chronic venous disease is partially mediated through leukocytes. The endothelium is activated and exhibits proliferation in the skin. Up-regulation of vascular endothelial growth factor (VEGF) expression in the skin of patients with chronic venous disease has been demonstrated with immunohistologic techniques. Abnormal VEGF expression can have local deleterious effects. The aim of this study was to determine whether patients with chronic venous disease have elevated plasma levels of VEGF. We conducted a prospective study with 30 patients with varicose veins of clinical, etiologic, anatomic, and pathologic class C3 (normal skin, n = 15) and C4 (trophic skin changes, n = 15) and 25 control subjects with no clinical evidence of venous or arterial disease of the lower limb. Blood samples were collected from a foot vein of each subject before and after a period of experimental venous hypertension produced by means of standing. Assay of VEGF protein was performed with a sandwich enzyme-linked immunosorbent assay. Plasma VEGF level was elevated in both groups of patients with venous disease compared with the control group. The median VEGF levels among patients were 81 pg/mL (interquartile range [IQR] 56 to 122) supine and 98 pg/mL (IQR 63 to 153) after standing for 30 minutes. Median VEGF levels among control subjects were 52 pg/mL (IQR 35 to 71) lying supine and 60 pg/mL (IQR 39 to 105) after standing for 30 minutes. Experimental venous hypertension caused a small rise in VEGF levels among the patients but not the control subjects. Further studies are required to determine whether increased VEGF expression contributes to tissue injury in chronic venous disease.

Adult↗
PubMed1994

The microcirculation in venous disease.

The author discusses three factors involved in venous ulceration: skin hypoxia, white-cell trapping, abnormalities in regulation of the microcirculation, eg, neuropathy. Leukocytes remain the most likely initiating factor.

Humans↗
PubMed1993

Does venous function deteriorate in patients waiting for varicose vein surgery?

We have looked at the deterioration in the condition of the lower limbs in a group of 36 patients who were waiting for a median time of 20 months for varicose vein surgery, using clinical examination, colour Duplex scanning and photoplethysmograph (95% refilling times). We found a significant deterioration in this group of patients, with four limbs initially unaffected developing reflux on Duplex scanning, of which three had clinical varicose veins (all four were offered surgery), and of the initial 56 involved limbs, 10 further sources of reflux were found (18%), necessitating alteration of the initial planned surgical procedure. No patient developed deep venous insufficiency or ulceration while on the waiting list, although there was one new case of lipodermatosclerosis. However, had surgery been undertaken after the first assessment, 14 patients (25%) would potentially have required further surgery, although accepting this as justification for allowing patients to wait takes no account of patients suffering or quality of life while waiting for operation.

Adult↗
PubMed1990

Venous stasis and vein lumen changes during surgery.

The mechanisms underlying the development of postoperative deep vein thrombosis remain to be fully elucidated. Previous studies have suggested that peroperative venous distension may be a factor associated with venous thromboembolism. In this study we have obtained high resolution ultrasound images of gastrocnemius and posterior tibial veins in 62 patients undergoing a range of general surgical procedures. From these we determined the changes in vein diameter occurring during the operative procedures, in response to induction of anaesthesia, and after completion of surgery. Veins showed no evidence of dilatation in response to the induction of anaesthesia, but by the end of the operative procedure showed distension of 22-28 per cent. Distension was most prominent in the gastrocnemius veins, and lesser distension was observed in the posterior tibial veins. In a series of patients who received an infusion of 1 litre of saline in addition to basal requirements, distension was 57 per cent compared with 22 per cent in the corresponding control group. Intraoperative venous distension is associated with factors that lead to deep vein thrombosis and may be involved in the mechanisms which result in the commencement of deep vein thrombosis.

Adult↗
PubMed1987

Photodynamic therapy with phthalocyanine sensitisation: quantitative studies in a transplantable rat fibrosarcoma.

Photodynamic therapy (PDT) is a promising approach to the local destruction of malignant tumours, but little work has been done to determine which factors control the extent of tissue necrosis produced. Using a new photosensitiser, a sulphonated aluminium phthalocyanine (AlSPc) and light from an argon ion pumped dye laser at 675 nm, we quantified the effects of interstitial PDT in a transplantable fibrosarcoma in rats. At 100mW laser power, thermal effects were comparable to those of PDT, so subsequent studies were carried out at 50 mW, where thermal effects were minimal. The depth of PDT necrosis increased with the logarithm of the applied energy. Tissue concentration of AlSPc was measured by alkali extraction and at all times after sensitisation, correlated well with the necrosis produced with a given light dose. Peak tumour concentration of AlSPc occurred 24-48 h after sensitisation compared with a peak at 3 h in muscle. The peak ratio tumour:muscle was 2:1 at 24 h. Apart from a different time interval to reach the peak sensitiser concentration, the extent of tumour damage varied with the light and sensitiser parameters in a similar way to that found in normal liver, although the optical penetration depth was greater in the tumour (2.5 mm vs. 1.8 mm). At doses of AlSPc below 1 mg kg-1 the diameter of necrosis increased with the logarithm of the dose of sensitiser, and doubling the dose from 0.25 to 0.5 mg kg-1 increased the depth of necrosis by 50%. However, at higher doses, the changes were smaller and increasing the dose from 2.5 to 5 mg kg-1 only increased the necrosis by 10% for the same light dose. In all dose ranges, a given percentage increase in the tissue concentration of AlSPc gave a much smaller percentage increase in the extent of necrosis for the same light dose, suggesting that selectivity of necrosis between tumour and normal tissue is likely to be much less than the selectivity of retention of the photosensitiser. From these results, the extent of PDT necrosis in this fibrosarcoma is as predictable as it is in normal liver if the light dose, tissue concentration of AlSPc and optical penetration depth of the tissue are known. Further studies are now required on different tumour models to establish how tumours respond compared with adjacent normal tissue when the tumour is growing in its organ of origin rather than the non-physiological situation using a transplantable tumour as in this study.

Aluminum↗
PubMed1987

Regimen for improved effectiveness of intermittent pneumatic compression in deep venous thrombosis prophylaxis.

The incidence of deep venous thrombosis (DVT) was assessed in a series of 78 patients undergoing major surgical operations to compare the prophylactic effectiveness of intermittent sequential pneumatic compression alone with the simultaneous use of graduated compression stockings and intermittent sequential pneumatic compression. The diagnosis of DVT was determined with the I-125 fibrinogen-uptake test, Doppler ultrasound, maximum venous outflow by strain-gauge plethysmography, and contrast venography. The incidence of DVT in nonstockinged legs was 9% while that in the stockinged legs was 1%. The simultaneous use of graduated elastic compression stockings and intermittent pneumatic compression is more effective than pneumatic compression alone in the prevention of postoperative DVT.

Adult↗
PubMed1984

Abdominal incisions--vertical or transverse?

Two-hundred and nine patients were entered into a prospective, randomized trial in order to determine whether a vertical or transverse abdominal incision is the more satisfactory in producing sound wounds. Ninety-six patients were randomized between paramedian and transverse incisions, and followed up for at least 1 year. No significant difference in the incidence of wound failure could be shown between 46 paramedian and 50 transverse incisions. Those patients who were considered to require a vertical incision were randomized between median and paramedian incisions. No significant difference in wound failure rates between 39 median and 40 paramedian incisions could be demonstrated. No advantage or disadvantage of a transverse over a vertical abdominal incision or of a paramedian over a median incision could be shown in this study.

Abdomen↗