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Optical microscopy can resolve detail at the larger end of the colloidal length scale, and to image suspensions at an individual particle level of resolution would allow the investigation of local behaviour in a way denied to the established scattering techniques. However, to achieve high-contrast single-particle resolution in dense suspensions that are thick enough to show behaviour the same as would be expected in the bulk is not a trivial exercise. We build on established advanced techniques of the conventional (i.e. non-confocal) light microscopy of phase objects to develop a suitable experimental protocol. Furthermore, we demonstrate the effectiveness of this protocol by means of an 'atlas' of the hard-sphere crystalline solid (where random stacking results in many complex facets), which should serve as a compendium for future study.

The aim of this study was to determine the incidence of complications of catheterization for total parenteral nutrition (TPN) in patients of the Parenteral Nutrition Unit of Groote Schuur Hospital. During the 2-year study period, 218 central venous catheters were inserted in 170 patients. The preferred technique of percutaneous infraclavicular subclavian venepuncture with subsequent subcutaneous tunnelling using a silicone elastomere catheter is described. The incidence of major complications of catheter insertion was 4,5% (pneumothorax 4, subclavian artery puncture 6). There was a 2,7% incidence of catheter malpositioning (requiring repositioning) at initial insertion. The mean duration of catheterization was 12,9 days. During this period there was a 6,9% incidence of mechanical complications (occluded lines 13, extravascular infusion 2). Catheter-related sepsis was suspected in 37 cases (16,9%) and all these catheters were removed, but in only 7 cases (3,2%) was the sepsis proved to be catheter-related. There was no correlation between the duration of catheterization and the development of catheter-related sepsis. Furthermore, there was no increase in the incidence of catheter sepsis in patients with sepsis before catheterization.

The technique of primary closure of the perineal wound combined with continuous irrigation and suction of the operative site has been used in 21 patients who underwent abdominoperineal excision for cancer of the rectum or anal canal. Primary healing occurred in 19 patients within 18 days, and all patients healed within 2 months. These results are in marked contrast to those in 38 patients treated with constant suction alone, of whom only 17 healed primarily.

A rare but potentially lethal complication of coumarin and its congeners is skin necrosis. A case of skin necrosis due to warfarin is reported and the literature is reviewed. It is suggested that if necrosis develops, the coumarin therapy should be terminated, and the patient should immediately be heparinized. Heparin, which never causes necrosis, can be used freely if further anticoagulation therapy is required, and may well prevent necrosis due to the thrombotic process.

Abdominoperineal excision of the rectum remains the accepted treatment for the majority of lower rectal adenocarcinomas. Despite advances in surgery and anaesthesia, survival has not improved over the last 40 years. Over a 12-year period the overall 5-year survival rate for patients undergoing abdominoperineal excision for adenocarcinoma of the rectum at Groote Schuur Hospital, Cape Town, was 39%. The incidence of complications associated with the operation remains high (36%). The major causes of morbidity still originate in the urinary tract and the perineal wound. Further techniques which may improve the overall survival are briefly reviewed.

A 15-year study of large-bowel carcinoma at Groote Schuur Hospital revealed 47 patients who presented at the age of 29 years or younger. Only 1% of the White patients with large-bowel carcinoma were in this age group (similar to other Western series), whereas a much higher incidence was seen in Coloured patients (9%). We found a large number of young Coloured patients with high-grade tumours and lymph node invasion. In spite of surgery, chemotherapy and radiotherapy the prognosis for this group in particular remains extremely poor.

Five thousand and twelve asymptomatic patients over the age of 40 years who were on a normal diet were asked by their general practitioners to perform a Hemoccult (Röhn Pharma (Noristan] faecal occult blood test over 3 days. Of the 3 422 patients (68%) who completed the test, 99 (3%) had a positive result. The patients with a positive result then again performed the Hemoccult test, this time over 6 days on a restricted diet. Thirty-two of these patients had a positive result on the second test. Only the 32 patients who had a positive result for the second test were fully investigated (including double-contrast barium enema and colonoscopy); 27 patients (84%) were found to have neoplastic disease. Twelve had invasive carcinoma (9 Dukes' A, 2 Dukes' B and 1 Dukes' C), 6 of these also having 10 adenomas, while the other 15 had 27 adenomas which were identified and removed at colonoscopy. Barium enema missed 3 carcinomas (all Dukes' A) and identified only 16 (43%) of the 37 adenomas. Those patients found to have a negative result for the second Hemoccult test are being followed up.