The deconvolution of differential scanning calorimetry unfolding transitions.

This paper is a review of a process for deconvolution of unfolding thermal transitions measured by differential scanning calorimetry. The mathematical background is presented along with illustrations of how the unfolding data is processed to resolve the number of sequential transitions needed to describe an unfolding mechanism and to determine thermodynamic properties of the intermediate states. Examples of data obtained for a simple two-state unfolding of a G-quadruplex DNA structure derived from the basic human telomere sequence, (TTAGGG)4TT are used to present some of the basic issues in treating the DSC data.

Pars plana vitrectomy with multiple transvenous chorioretinotomies for macular edema due to retinal vein occlusion.

Background And Objective: To review results of vitreous surgery for branch and central retinal vein occlusion (BRVO and CRVO).

Patients And Methods: All cases of vitrectomy with multiple transvenous chorioretinotomies for retinal vein occlusion at a vitreoretinal subspecialty practice were reviewed.

Results: Twenty eyes of 20 patients (four with BRVO and 16 with CRVO) were included.

Structure and stability of higher-order human telomeric quadruplexes.

G-quadruplex formation in the sequences 5'-(TTAGGG)(n) and 5'(TTAGGG)(n)TT (n = 4, 8, 12) was studied using circular dichroism, sedimentation velocity, differential scanning calorimetry, and molecular dynamics simulations. Sequences containing 8 and 12 repeats formed higher-order structures with two and three contiguous quadruplexes, respectively. Plausible structures for these sequences were determined by molecular dynamics simulations followed by experimental testing of predicted hydrodynamic properties by sedimentation velocity.

Long-term safety, high-resolution imaging, and tissue temperature modeling of subvisible diode micropulse photocoagulation for retinovascular macular edema.

Purpose: To determine the long-term safety of high-density subvisible diode micropulse photocoagulation (810 nm), compare the clinical findings with computational modeling of tissue hyperthermia and to report results for a subset of eyes treated for diabetic macular edema (ME) documented pre- and postoperatively by spectral-domain optical coherence tomography.

Method: All eyes treated for ME from diabetic retinopathy (diabetic ME) and branch retinal vein occlusion between April 2000 and January 2010 were reviewed for subvisible diode micropulse laser-induced retinal damage. Therapeutic outcomes were reviewed for a subgroup treated for diabetic ME with pre- and postoperative spectral-domain optical coherence tomography.

Thermodynamics of forming a parallel DNA crossover.

The process of genetic recombination involves the formation of branched four-stranded DNA structures known as Holliday junctions. The Holliday junction is known to have an antiparallel orientation of its helices, i.e.

Vitrectomy after anti-VEGF therapy for epiretinal membranes coincident with age-related subfoveal choroidal neovascularization.

Background And Objective: To report the visual acuity results in a small case series of eyes undergoing membrane peeling for epiretinal membrane presenting with age-related subfoveal choroidal neovascularization.

Patients And Methods: Retrospective chart review of all eyes undergoing vitrectomy with epiretinal membrane peeling after intravitreal anti-vascular endothelial growth factor injection treatment for age-related subfoveal choroidal neovascularization presenting between February 2005 and January 2007 to a private vitreoretinal subspecialty practice.

Results: Four eyes of four patients observed for 10-23 months (median = 20.

Differential scanning calorimetry.

Differential scanning calorimetry (DSC) has emerged as a powerful experimental technique for determining thermodynamic properties of biomacromolecules. The ability to monitor unfolding or phase transitions in proteins, polynucleotides, and lipid assemblies has not only provided data on thermodynamic stability for these important molecules, but also made it possible to examine the details of unfolding processes and to analyze the characteristics of intermediate states involved in the melting of biopolymers. The recent improvements in DSC instrumentation and software have generated new opportunities for the study of the effects of structure and changes in environment on the behavior of proteins, nucleic acids, and lipids.

Prolongation of choroidal hypofluorescence following combined verteporfin photodynamic therapy and intravitreal triamcinolone acetonide injection.

Purpose: To determine the incidence and effect of persistent/prolonged choroidal hypofluorescence (PCH) following combined verteporfin photodynamic therapy and intravitreal triamcinolone acetate injection (PDT + IVTA) for age-related subfoveal choroidal neovascularization (CNVM).

Method: A retrospective review of all patients undergoing PDT + IVTA for CNVM from December 2003 through November 2004 was performed. Included patients underwent intravenous fundus fluorescein angiography (FA) preoperatively and 1 week and 3 months following PDT.

Serial optical coherence tomography of subthreshold diode laser micropulse photocoagulation for diabetic macular edema.

Background And Objective: To use serial optical coherence tomography (OCT) to evaluate low-intensity, high-density subthreshold diode laser micropulse photocoagulation treatment of clinically significant diabetic macular edema.

Patients And Methods: Eighteen consecutive eyes of 14 patients with clinically significant diabetic macular edema and a minimum foveal thickness of 223 microm or greater were prospectively evaluated by OCT preoperatively and 1, 4, and 12 weeks following treatment.

Results: Overall, estimated macular edema 3 months postoperatively (minimum foveal thickness--223 microm) was reduced a mean of 24% (P = .

Enthalpies of DNA melting in the presence of osmolytes.

The melting of DNA in the presence of osmolytes has been studied with the intention of obtaining information about how base pair stability is affected by changes in solution conditions. In previous investigations, the melting enthalpies were assumed to be constant as osmolalities change, but no systematic evaluation of whether this condition is true has been offered. This paper presents calorimetric data on the melting of two synthetic DNA samples in the presence of a number of common osmolytes.

Effects of small neutral osmolytes on the supercoiling free energy and intrinsic twist of p30delta DNA.

Both theory and experiments are employed to investigate the effects of small neutral osmolytes on the average intrinsic twist (l0), the torsion and bending elastic constants, and the twist energy parameter (ET) that governs the supercoiling free energy. The experimental data for ethylene glycol and acetamide at 37 degrees C suggest, and are interpreted in terms of, a model wherein the DNA exhibits an equilibrium between two distinct conformational states that possess different numbers of bound water molecules and exhibit different intrinsic twists and torsion and bending elastic constants. Expressions are derived to relate the effective ET and l0 to the equilibrium constant, water activity (aw), and number (n) of bound water molecules released per cooperative domain undergoing the two-state transition.