This symposium marks the 15th anniversary of the discovery of microbodies in methylotrophic yeasts. In the intervening years much has been learned about the structure, function and biogenesis of these organelles and these advances are described. As our endeavours continued, unexpected results have confused commonly held views. This was for instance the case when microbody-minus mutants of yeasts became available which showed that some microbody matrix enzymes may be functional when present in the cytosol while others are not. At the molecular level, our understanding of structure/function relationships is also expanding. Examples are structural elements which relate to protein topogenesis and function of enzymes in different cell compartments. Other, perhaps more unusual, adaptations have also been encountered; some involve protein-protein interactions or even modified cofactors which possibly have helped methylotrophic yeasts to establish and/or maintain themselves in natural ecosystems.A long-term clinical trial of 1-15 months has been carried out with the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1) in 13 transfusion-dependent iron-loaded patients. Urinary iron excretion was greatest in patients with thalassaemia major and was related to the number of previous transfusions but not to the serum ferritin level. Substantial increases of urinary iron were observed in all the patients when the frequency of the daily dose was doubled and in response to 2 x 3 g L1 daily 11 of 12 patients tested excreted greater than 25 mg iron daily, the mean daily intake of iron from transfusion. Serum ferritin levels have fluctuated but overall have remained unchanged. Pharmacological studies in five patients have indicated rapid absorption probably from the stomach and variable plasma half life of 77 +/- 35 min (X +/- SD). Glucuronation was identified as a major route of L1 metabolism. Short-term intensive chelation studies using repeated administration of L1 resulted in further increases of urinary iron excretion by comparison to a single dose. In one case 325 mg of iron were excreted in the urine following the administration of 16 g (5 x 2 g + 2 x 3 g) within 24 h. Iron excretion studies were carried out in six transfusional iron-loaded patients who were maintained on a low iron diet before and during chelation. No significant increases of faecal iron excretion were observed with L1 using daily doses of up to 3 x 3 g and 4 x 2 g. The high level of compliance during treatment with L1 and the levels of urine iron excretion that can be achieved increase the prospects for oral chelation in transfusional iron-loaded patients.One year following root canal treatment and internal etching and bleaching of anterior teeth in dogs, the animals were sacrificed and the teeth prepared for stereomicroscopic or light microscopic examination. Evidence of cervical root resorption and ankylosis was noted on several teeth. The bleaching factors associated with the teeth exhibiting resorption were heat with 30% hydrogen peroxide. Resorption was not related to walking bleach or to internal etching alone.The application of microsurgical tissue transplantation in craniomaxillofacial deformities is presented by regional anatomic examples and discussion.Because cases of unrecognized carbon monoxide (CO) poisoning have been described among patients admitted to the hospital with other diagnoses, screening hospital admissions with carboxyhemoglobin testing has the potential for preventing morbidity among patients as well as among their cohabitants. Carboxyhemoglobin levels were obtained on 753 patients admitted to the hospital from the emergency department over a 3-month period during the winter. Patients in whom CO poisoning was diagnosed in the emergency department prior to admission were excluded. The mean carboxyhemoglobin level was 2.52% +/- 1.85%; there was no significant difference in mean carboxyhemoglobin among patients with medical, surgical, neurological, and psychiatric admission diagnoses (F = 1.17; df = 3,746; P =.32). Two patients (0.3%; 95% confidence limits, 0.04% to 1.1%) from the entire admission cohort, and one of 20 patients (5%; 95% confidence limits, 0.3% to 26.9%) admitted with seizures, had carboxyhemoglobin levels greater than 10%. The carboxyhemoglobin levels of the two patients were only marginally elevated, with levels of 10.9% and 11.3%. The cost of the carboxyhemoglobin screening program was $2.26 per patient result, or approximately $2,100 over a 3-month winter heating season. A program for screening emergency department admissions with carboxyhemoglobin testing, although feasible in terms of cost, detected few cases of unrecognized CO poisoning.The importance of an internal shock absor