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This study provides preliminary insights into how the culture method of molluscs and the larval developmental mode of pest polydorids may determine which species become pests. A total of 10 species were identified on oysters and abalone in offshore and oysters in onshore culture on the west coast of South Africa. One-factor PERMANOVA showed that abalone and oysters cultured offshore housed similar communities of worms, but that they differed significantly from the communities housed by oysters cultured onshore. Oysters from onshore were infested mainly by Polydora hoplura, but also by Polydoracf. websteriand Boccardia pseudonatrix. All these species produce adelphophagic larvae or a mixture of these and planktotrophic larvae. Adelphophagic larvae usually only emerge soon before they settle, which would probably enhance their ability to recruit locally and establish local populations. By contrast, worms from molluscs grown offshore were infested by high abundances of P. hopluraand lower abundances of up to five more species per individual host. All hatched broods observed with these female P. hopluracontained planktotrophic larvae which have a long planktonic phase before settling. This would presumably enhance their ability to reach hosts in the offshore.

Aortic graft infection is a rare, but grave, complication in vascular surgery. Graft removal together with extra-anatomical bypass or in situ graft replacement is usually advocated, but these procedures are associated with significant morbidity and mortality.

Aims:The purpose of this study was to develop and validate an easily used disease-specific quality of life (QOL) measure for patients with chronic lower limb ischemia and to design an evaluative instrument, responsive to withinsubject change, that adds to clinical measures of outcome when comparing treatment options in the management of lower limb ischemia. Methods:The first phase consisted of item generation, item reduction, formulating, and pretesting in patients with ischemia. The proportion of patients who selected an item as troublesome and the mean importance they attached to it were combined to give a clinical impact factor. Items with the highest clinical impact factor were used to formulate a new 25-item questionnaire that was then pretested in 20 patients with lower limb ischemia. In the second phase, reliability, validity, and responsiveness of the new questionnaire were assessed in 39 patients with lower limb ischemia who were tested at 0 and 4 weeks. The King's College Hospital's Vascular Quality of Life Questionnaire and the Short-Form 36 were administered at each visit, and treadmill walking distance and ankle/brachial pressure indices were recorded. The new questionnaire's reliability, internal consistency, responsiveness,and validitywere determined. Results:Areas of QOL impairment were consistent through the ranges of disease severity and age, with no apparent differences between the men and women. Therefore, a single questionnaire is applicable to all patients with chronic lower limb ischemia. In stable patients test-retest scores demonstrated a reliability of rmore than 0.90. Each item had internal consistency (item-domain Cronbach α =.7-.9). The questionnaire was responsive to change, with correlation between change in the questionnaire's total score and both global and clinical indicators of change (P<.001). The questionnaire showed faceand constructvalidity. Conclusions:This disease-specific questionnaire is reliable, responsive, valid, and ready for use as an outcome measure in clinical trials. It is sensitive to the concerns of patients with lower limb ischemia, offering a simple method to measure the effect of interventions on their QOL. (J Vasc Surg 2001;33:679-87.)