Potential for cadaveric organ retrieval in New South Wales.

OBJECTIVES--To measure the potential for cadaver organ retrieval in New South Wales and to determine the reasons for potential donors failing to become actual donors. DESIGN--Prospective audit of all patients dying in five hospitals in New South Wales between 1 December 1989 and 30 November 1990; quality assurance of the data by independent medical specialist and if disagreement by study committee. PATIENTS--2879 patients (100% of all deaths) yielding 364 patients with coma and 181 potential donors. OUTCOME MEASURES--Realistic medically suitable potential donor rate, missed potential donor rate, rate of potential donors with permission refused, donor rate, reasons for realistic medically suitable potential donors failing to become actual donors. RESULTS--2879 deaths yielded 73 medically suitable potential donors, resulting in 19 actual donors, 30 missed potential donors, 19 potential donors with permission refused, and five in whom adequate resuscitation failed. The most common reason for a potential donor failing to become an actual donor was a decision by the senior medical practitioner to withdraw or not to institute ventilatory or haemodynamic support (26/73). The second major obstacle was refusal of permission by the next of kin (17/73). Assuming that the potential donor rate was that implied by the observed donor rate (13/million population/year) the projected missed potential donor rate was 9/million population/year (95% confidence interval 4 to 15) and the projected rate of potential donors with permission refused was 13/million population/year (95% confidence interval 5 to 22). Assuming that the rate of potential donors in the study hospitals was the same as in the other New South Wales hospitals, the projected donor rate for New South Wales was 18/million population/year (10 to 26); the projected missed potential donor rate was 15/million population/year (7 to 23); and the projected rate of potential donors with permission refused was 18/million population/year (10 to 27). CONCLUSIONS--The donor rate could be increased 70%-80% by overcoming the reluctance of medical practitioners to resuscitate missed potential donors and increased further by gaining permission for organ retrieval from the next of kin.     

The structure and phylogenetic significance of the flagellar transition region in the chlorophyll c-containing algae.

An electron-dense helix is the most conspicuous structure in the flagellar transition region of members of the algal class Chrysophyceae. This “transitional helix” (TH) lies immediately distal to a partition across the flagellar axoneme which occurs exactly at the level at which the flagellum enters the cell body. The helix surrounds the central axonemal pair and lies at a distance of 10 nm from the 9 peripheral doublets. From the new data presented and a survey of published observations on the structure of the transition region of all the chlorophyll c-containing classes of algae, it is shown that a TH characteristic of the Chrysophyceae, Xanthophyceae and Eustigmatophyceae. The number of TH gyres varies from 3 to 6 in the Xanthophyceae and from 1 to 8 in the Chrysophyceae. In any one species, however, the TH is the same size in both the long flagellum which bears tubular mastigonemes and in the short smooth flagellum, though in some chrysophytes where the short flagellum is vestigial the number is fewer than in the normal flagellum. A TH appears to be absent from the Rhaphidophyceae and zoids of the Bacillariophyceae and Phaeophyceae though the structure of the transition region in these groups otherwise resembles that of the Chrysophyceae, Xanthophyceae and Eustigmatophyceae.The value of transition region variation in determining evolutionary relationships among the chlorophyll c-containing algal classes is assessed against a background of current ideas on their taxonomy and phylogeny. The relevant structural and biochemical features are tabled, and a phylogenetic scheme is presented which appears most logically to interpret these data. It is suggested that the line leading to the Eustigmatophyceae probably diverged from that leading to the strictly heterokont classes Xanthophyceae, Chrysophyceae, Phaeophyceae and Bacillariophyceae before evolution of a girdle lamella in the chloroplast and a photoreceptor apparatus involving a swelling at the proximal end of the short flagellum and an intraplastidial eyespot. The possession of a TH by both the Chrysophyceae and Xanthophyceae adds further support to the concept of their close relationship based on a range of other features. The exceptional absence of a TH from the chrysophycean genera Pedinella and Pseudopedinella reinforces the idea that these taxa are remote from the main chrysophycean line. Absence of a TH from the Phaeophyceae and Bacillariophyceae which otherwise share many important features with the Chrysophyceae and Xanthophyceae is probably a result of loss owing to the functional and morphological specialization of the zoids of these two groups. Transition region structure does not clarify the possible relationships of the Rhaphidophyceae, Prymnesiophyceae, Cryptophyceae or Dinophyceae.The proposed phylogeny supports the idea of a mutually related “heterokont” protist assemblage comprising the Chrysophyceae, Xanthophyceae, Phaeophyceae, Bacillariophyceae and possibly Rhaphidophyceae and the Oomycetes (water moulds) though in the latter the TH is replaced by a dense cylinder with a corrugated wall which may or may not be homologous with it. Structures resembling a TH have been described in a wide variety of other flagellated cells including the prasinophyte Pyraminonas orientalis, one species of the colourless flagellate genus Bicosoeca and the proteromonads Karotomorpha and Proteromonas. Only in the latter genera does homology with a TH seem likely on present evidence, suggesting that flagellates of this type may have evolved from chrysomonad-like ancestors.