Fine-tuning transmission electron microscopy methods to evaluate the cellular architecture of Ulvacean seaweeds (Chlorophyta).

Chemical fixation is a critical step in the analysis of the ultrastructure of seaweeds because the wrong approach can compromise the ability to distinguish fine-scale cellular composition. Fixation agents, fixation time and type of tissue are important factors to consider for transmission electron microscopy (TEM), and not every protocol is suitable for all cell types. We evaluated a range of fixation agents, post-fixation time and dehydration solutions to determine a TEM protocol for seaweeds in the Family Ulvaceae. We assessed Ulva lactuca using 5 protocols. The level of preservation obtained differed markedly between fixation methods The best result was obtained by fixing the sample with 2.5% glutaraldehyde, 0.05M sodium cacodylate buffer and 2% paraformaldehyde overnight, and 8h post-fixation in 1% in osmium tetroxide 1%. This approach and fixation time ensured that the membranes, especially the thylakoid membranes of chloroplasts, remained intact. Ethanol is recommended for dehydration as the use of acetone for dehydration resulted in the collapse of cellular membranes. This new protocol will ensure the ultrastructure of Ulvacean seaweeds can be clearly ascertained in the future.

Modelling the "ideal" self care--limited care dialysis center.

Limited care dialysis is an interesting option, which has gained attention in several settings because of the aging of the uremic cohort. The aim of this study was to assess its potential in the Piedmont region in northern Italy, evaluating patients' and care-givers' preferences and testing them in a mathematical model of organisation. The study was conducted in the satellite unit of a university hospital (200-210 dialysis patients), following 35 patients (15 at home, 20 in the center, 10 on daily dialysis). Opinions were collected with a questionnaire and features identified were empirically tested through a simulation model. Most patients (34/35) preferred a small unit, with a stable caring team. Further options were flexibility of dialysis schedule, multiple treatment options, integrated center/home care. These needs could be met by a flexible organization including conventional dialysis (3/week) and daily dialysis (6/week). We employed a simulation model (ARENA software) to calculate the nurses required for each shift and the opening hours and best schedule for the unit. Addition of daily dialysis (2-3 hours) to two conventional 4-5 hour sessions to increased the number of patients followed or "spared" beds, ensuring flexibility. According to patients' best choice (7 dialysis stations), and to the recorded calls, the needs are for two nurses per shift, two shifts per day and six nurses for up to 30 patients in limited care. In conclusion, small centers with flexible schedules can tailor dialysis to patients' needs. A managerial approach is valuable for testing cost/benefit ratios in specific contexts.