To evaluate the safety of an intensive cataract surgery training programme.
An intensive cataract surgery training programme was implemented in August 2010 for year 3 ophthalmology trainees in the ...East Midlands Deanery North Rotation (United Kingdom). Trainees participated in extra-ocular surgery and 50 h of virtual reality cataract surgery simulator training over a 2-year period. Their third year comprised 6 months of intensive phacoemulsification training in a tertiary centre followed by a 6-month period of consolidation in a district general hospital. The complication rates and case numbers were evaluated after the first 2 years of implementation.
At 2 years, three trainees had completed a full year of intensive training. In the first 6 months of training, Trainee 1 completed 156 cases, Trainee 2 completed 194 cases, and Trainee 3 completed 151 full cases as primary surgeons with an average rate of posterior capsule rupture (PCR) of 1%. At 12 months, Trainee 1 completed 291, Trainee 2 completed 318, and Trainee 3 completed 294 cases, with an average PCR rate of 0.66%. The trainees required 84 lists on average to complete 150 full cataract procedures.
The combination of simulation and the new intensive training programme is safer than the traditional programme for cataract surgery training.
The present study was conducted to develop targeted region amplification polymorphism (TRAP) and start codon targeted polymorphism (SCoT) DNA markers for the identification of somaclonal variation in ...cryopreserved Dendrobium Bobby Messina. With reference to previous orchid cryopreservation via PVS2 (plant vitrification solution) vitrification methods, regenerated explants were assessed in order to determine the genetic similarity in comparison to the mother plant. 3 different samples were selected involving stock culture PLBs (protocorm-like bodies), non-cryopreserved PLBs and thawed cryopreserved PLBs. During the study, eight pairs of (8) TRAP primers (TRAP CMS TRAP 8-4A, FLS TRAP 2-2A, TRAP 14-5A, TRAP 20-6B, TRAP 16-3B, ChIC TRAP 5-5B, TRAP3-1D and TRAP 9-5A) produced unambiguous and reproducible bands ranging from 100 to 2000bp. In cryopreserved PLBs, all TRAP primers displayed polymorphic bands. In the non-cryopreserved PLBs, primer TRAP 20-6B produced monomorphism and the remaining 7 showed both complete and partial polymorphism, respectively. SCoT markers indicated that four primers were able to generate reproducible and clear bands at the sizes of 500 to 3000bp. SCoT primers (S26, S32, S33 and S36) showed polymorphism for both cryopreserved and non-cryopreserved PLBs of Dendrobium Bobby Messina. The TRAP and SCoT DNA markers designed were found to be an efficient tool to evaluate potential rate of somaclonal variations of regenerated PLBs following cryopreservation.
•Both TRAP and SCoT markers displayed somaclonal variation in regenerated cryopreserved PLBs of Dendrobium Bobby Messina.•These techniques offers an effective approach in detecting somaclonal variation following cryopreservation.•To our knowledge, this study is the first to be conducted for Dendrobium Bobby Messina utilizing TRAP and SCOT markers for the analysis of genetic variation in cryopreservation research in orchids.
The structure and dynamics of the lipid and water components of dioleoylphosphatidylcholine bilayers at various levels of hydration were studied using molecular dynamics (MD) simulations. ...Equilibration of these systems proceeded by use of a hybrid MD and configurational-bias Monte Carlo technique using one atmosphere of pressure normal to the membrane and a set point for the lateral area derived from experimental Bragg spacings, combined with experimentally derived specific volumes for each of the system components. Membrane surface tensions were observed to be of the order of tens of dyn/cm. The transbilayer molecular fragment peak positions at low hydration were found to agree with experimental neutron and x-ray scattering profiles and previously published simulations. For hydration levels of 5.4, 11.4, and 16 waters/lipid, molecular fragment distributions and order parameters for the headgroup, lipid chains, and water were quantified. Spin-lattice relaxation rates and lateral self-diffusion coefficients of water agreed well with results from experimental nuclear magnetic resonance studies. Relaxation rates of the choline segments and chemical shift anisotropies for the phosphate and carbonyls were computed. Headgroup orientation, as measured by the P-N vector, showed enhanced aligment with the membrane surface at low hydration. The sign of the membrane dipole potential reversed at low hydration, with the membrane interior negative relative to the interlamellar region. Calculation of the number of water molecules in the headgroup hydration shell, as a function of hydration level, supports the hypothesis that the break point in the curve of Bragg spacing versus hydration level near 12 waters/lipid, observed experimentally by Hristova and White (1998.
Biophys. J. 74:2419–2433), marks the completion of the first hydration shell.
Previous mutagenesis studies with bacteriorhodopsin have shown that reprotonation of the Schiff's base is the rate-limiting step in the photocycle of the D96N mutant, whereas retinal re-isomerization ...and return of the protein to the initial state constitute the rate-limiting events in the photocycle of the L93A mutant. Thus, in the D96N mutant, decay of the M intermediate is slowed down by more than 100-fold at pH 7. In the L93A mutant, decay of the O intermediate is slowed down by 250-fold. We report here that in the L93A, D96N double mutant, decay of the M intermediate, as well as the formation and decay of the O intermediate, are slowed down dramatically. The photocycle is completed by the decay of a long-lived O intermediate, as in the L93A mutant. The decay of the M and O intermediates in the double mutant parallels the behavior seen in the single mutants over a wide temperature and pH range, arguing that the observed independence is an intrinsic property of the mutant. The slow decay of the M and O intermediates can be selectively and independently reversed under conditions identical to those used for the corresponding intermediates in the D96N and L93A single mutants. Because the effects of the two individual mutations are preserved in the double mutant and can be independently reversed, we conclude that residues Asp 96 and Leu 93 act independently and at different stages of the bacteriorhodopsin photocycle. These results also show that formation of the O intermediate only requires protonation of the Schiff's base and is independent of the protonation of Asp 96 from the aqueous medium.
Protocorm-like bodies (PLBs) of Brassidium Shooting Star, a new commercial ornamental orchid hybrid, were cryopreserved by an encapsulation-dehydration technique. The effects of PLB size, various ...sucrose concentrations in preculture media and sodium alginate concentration for encapsulation were the main parameters assessed. Four-week old PLBs (1 to 2 and 3 to 4 mm) were precultured in half strength semi-solid Murashige and Skoog (MS) media supplemented with six different sucrose concentrations (0, 0.2, 0.4, 0.6, 0.8 and 1.0 M) for 24 h, followed by encapsulation in 2.5, 3.0 or 3.5% sodium alginate, with 0.1 M calcium chloride been used as the hardening agent. The beads formed were then osmoprotected in half-strength liquid MS media supplemented with 0.75 M sucrose and dehydrated for three hours in 50 g heat-sterilized silica gel before cryostorage in sterile cryovials. The beads were thawed in a 40 plus or minus 2 degree C water bath and then directly placed in recovery media for two weeks under tissue culture conditions. After two weeks of recovery, the survival rates of the encapsulated PLBs were evaluated by the 2, 3, 5-triphenyltetrazolium chloride (TTC) assay. The best conditions for the encapsulaten-dehydration of Brassidium Shooting Star were discovered to be the preculture of 3 to 4mm PLB in half strength semi-solid MS media supplemented with 0.8 M sucrose, followed by encapsulation in 3.5% sodium alginate. Further biochemical analysis (chlorophyll, total soluble protein and peroxidases activities) were conducted to investigate the physiological responses of the PLBs after cryopreservation.
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