Three-dimensional decision support system for treatment of canine impaction.

Introduction: This study aimed to develop a 3-dimensional (3D) characterization of the severity of maxillary impacted canines and to test the clinical performance of this characterization as a treatment decision support tool.

Methods: Cone-beam computed tomography images obtained from 83 patients with 120 impacted maxillary canines were included. Quantitative information on the canine 3D position and qualitative assessment of root damage of adjacent teeth were evaluated.

Presurgical orthodontic decompensation with clear aligners.

Introduction: Orthodontists, surgeons, and patients have taken an interest in using clear aligners in combination with orthognathic surgery. This study aimed to evaluate the accuracy of tooth movements with clear aligners during presurgical orthodontics using novel 3-dimensional superimposition techniques.

Methods: The study sample consisted of 20 patients who have completed presurgical orthodontics using Invisalign clear aligners.

Dental long axes using digital dental models compared to cone-beam computed tomography.

Objective: Standard methods of evaluating tooth long axes are not comparable (digital dental models [DDMs], panoramic and cephalometric radiographs) or expose patients to more radiation (cone-beam computed tomography [CBCT]). This study aimed to compare angular changes in tooth long axes using DDMs vs using CBCTs.

Settings And Sample Population: Secondary data analysis of DDMs and CBCTs, taken before and after orthodontic treatment with piezocision of 24 patients.

Correlation of tryptophan fluorescence spectral shifts and lifetimes arising directly from heterogeneous environment.

Tryptophan (Trp) fluorescence is potentially a powerful probe for studying the conformational ensembles of proteins in solution, as it is highly sensitive to the local electrostatic environment of the indole side chain. However, interpretation of the wavelength-dependent complex fluorescence decays of proteins has been stymied by controversy about two plausible origins of the typical multiple fluorescence lifetimes: multiple ground-state populations or excited-state relaxation. The latter naturally predicts the commonly observed wavelength-lifetime correlation between decay components, which associates short lifetimes with blue-shifted emission spectra and long lifetimes with red-shifted spectra.

Allosteric suppression of HIV-1 reverse transcriptase structural dynamics upon inhibitor binding.

Efavirenz is a second-generation nonnucleoside reverse transcriptase inhibitor (NNRTI) and a common component of clinically approved anti-AIDS regimens. NNRTIs are noncompetitive inhibitors that bind in a hydrophobic pocket in the p66 subunit of reverse transcriptase (RT) ∼10 Å from the polymerase active site. Hydrogen exchange mass spectrometry (HXMS) shows that efavirenz binding reduces molecular flexibility in multiple regions of RT heterodimer in addition to the NNRTI binding site.

Efavirenz binding site in HIV-1 reverse transcriptase monomers.

Efavirenz (EFV) is a potent nonnucleoside reverse transcriptase inhibitor (NNRTI) used in the treatment of AIDS. NNRTIs bind in a hydrophobic pocket located in the p66 subunit of reverse transcriptase (RT), which is not present in crystal structures of RT without an inhibitor. Recent studies showed that monomeric forms of the p66 and p51 subunits bind efavirenz with micromolar affinity.

Efavirenz binding to HIV-1 reverse transcriptase monomers and dimers.

Efavirenz (EFV) is a nonnucleoside reverse transcriptase inhibitor (NNRTI) of HIV-1 reverse transcriptase (RT) used for the treatment of AIDS. RT is a heterodimer composed of p66 and p51 subunits; p51 is produced from p66 by C-terminal truncation by HIV protease. The monomers can form p66/p66 and p51/p51 homodimers as well as the p66/p51 heterodimer.

Kinetics of association and dissociation of HIV-1 reverse transcriptase subunits.

The biologically active form of HIV-1 reverse transcriptase (RT) is the p66/p51 heterodimer. The process of maturation of the heterodimer from precursor proteins is poorly understood. Previous studies indicated that association of p66 and p51 is very slow.

Solution structural dynamics of HIV-1 reverse transcriptase heterodimer.

Crystal structures and simulations suggest that conformational changes are critical for the function of HIV-1 reverse transcriptase. The enzyme is an asymmetric heterodimer of two subunits, p66 and p51. The two subunits have the same N-terminal sequence, with the p51 subunit lacking the C-terminal RNase H domain.

Dependence of tryptophan emission wavelength on conformation in cyclic hexapeptides.

The wavelength of maximum emission of tryptophan depends on the local electrostatic environment of the indole chromophore. The time-resolved emission spectra of seven rigid cyclic hexapeptides containing a single tryptophan residue were measured. The emission maxima of the three decay-associated spectra for the seven peptides ranged from 341 to 359 nm, suggesting that different tryptophan rotamers have different emission maxima even in the case of solvent-exposed tryptophans.

Effects of efavirenz binding on the subunit equilibria of HIV-1 reverse transcriptase.

Recent studies showed that nonnucleoside reverse transcriptase inhibitors (NNRTIs) have variable effects on dimerization of p66 and p51 subunits of HIV-1 reverse transcriptase (RT). Efavirenz, one of three NNRTIs currently used in highly active anti-retroviral therapy, enhances subunit dimerization. Sedimentation equilibrium experiments on each subunit and equimolar mixtures of both subunits were used to measure dissociation constants for the three coupled dimerization reactions of RT in the absence and presence of saturating concentrations of the drug.

Attenuation of DNA replication by HIV-1 reverse transcriptase near the central termination sequence.

Previous pre-steady-state kinetic studies of equine infectious anemia virus-1 (EIAV) reverse transcriptase (RT) showed two effects of DNA substrates containing the central termination sequence (CTS) on the polymerization reaction: reduction of burst amplitude in single nucleotide addition experiments and accumulation of termination products during processive DNA synthesis [Berdis, A. J., Stetor, S.

Conformational effects on tryptophan fluorescence in cyclic hexapeptides.

The peptide bond quenches tryptophan fluorescence by excited-state electron transfer, which probably accounts for most of the variation in fluorescence intensity of peptides and proteins. A series of seven peptides was designed with a single tryptophan, identical amino acid composition, and peptide bond as the only known quenching group. The solution structure and side-chain chi(1) rotamer populations of the peptides were determined by one-dimensional and two-dimensional (1)H-NMR.

Barriers to nutrition education for older adults, and nutrition and aging training opportunities for educators, healthcare providers,volunteers and caregivers.

Literature citations of barriers to nutrition education found in those who teach and care for older adults, as well as within older adults themselves, are discussed. No attempt was made to compare educational barriers for learners of varying ages. These obstacles need to be addressed in order for nutrition to be taught or learned effectively so that nutrition practices and health improve.

Improving effectiveness of nutrition education resources for older adults.

This article discusses published reports and studies from the past decade that focused primarily on using written or other tangible nutrition educational resources with older adults, such as brief "handouts," newsletters, brochures, booklets, curricular lessons, board games, audiotapes and videotapes. Studies of health professionals' needs and desires for such materials are also reviewed. Thirteen articles, of which four were theory-based, were found.

Concepts, theories and design components for nutrition education programs aimed at older adults.

This article examines characteristics of older adult learners and discusses adult education theory and empowerment concepts, along with nutrition education and behavioral change strategies for older adult nutrition education programs. Design components for older adult nutrition education programs are presented. Educational and behavioral change strategies should be selected based on characteristics of the intended audience, including their nutrition needs, wants and desires, and should be based on appropriate theory.

Tailoring nutrition education intervention programs to meet needs and interests of older adults.

Methods for determining appropriate content of older adult nutrition education intervention programs and strategies for effectively delivering nutrition messages to older learners are presented. Educators can determine the nutrition education needs and interests of their older learners by using results of food intake surveys and assessment screening tools, written surveys, interviews and group discussions. Findings of recent reports using these methods are summarized.

Two-step FRET as a structural tool.

The power of FRET to study molecular complexes is expanded by the use of two or more donor/acceptor pairs. A general theoretical framework for distance measurements in three-chromophore systems is presented. Three energy transfer schemes applicable to many diverse situations are considered: (I) two-step FRET relay with FRET between the first and second chromophores and between the second and third, (II) FRET from a single donor to two different acceptors, and (III) two-step FRET relay with FRET also between the first and third chromophores.

Endogenous tryptophan residues of cAPK regulatory subunit type IIbeta reveal local variations in environments and dynamics.

The amino terminal dimerization/docking domain and the two-tandem, carboxy-terminal cAMP-binding domains (A and B) of cAMP-dependent protein kinase regulatory (R) subunits are connected by a variable linker region. In addition to providing a docking site for the catalytic subunit, the linker region is a major source of sequence diversity between the R-subunit isoforms. The RIIbeta isoform uniquely contains two endogenous tryptophan residues, one at position 58 in the linker region and the other at position 243 in cAMP-binding domain A, which can act as intrinsic reporter groups of their dynamics and microenvironment.

RNA polymerase alters the mobility of an A-residue crucial to polymerase-induced melting of promoter DNA.

Strand separation in promoter DNA induced by Escherichia coli RNA polymerase is likely initiated at a conserved A residue at position -11 of the nontemplate strand. Here we describe the use of fluorescence techniques to study the interaction of RNA polymerase with the -11 base. Forked DNA templates were employed, containing the fluorescent base, 2-aminopurine (2AP), substituted at the -11 position in a single-stranded tail comprising the nucleotides on the nontemplate strand at which base pairing is disrupted in an RNA polymerase-promoter complex.

Fluorescence of cis-1-amino-2-(3-indolyl)cyclohexane-1-carboxylic acid: a single tryptophan chi(1) rotamer model.

A constrained derivative, cis-1-amino-2-(3-indolyl)cyclohexane-1-carboxylic acid, cis-W3, was designed to test the rotamer model of tryptophan photophysics. The conformational constraint enforces a single chi(1) conformation, analogous to the chi(1) = 60 degrees rotamer of tryptophan. The side-chain torsion angles in the X-ray structure of cis-W3 were chi(1) = 58.

Intramolecular quenching of tryptophan fluorescence by the peptide bond in cyclic hexapeptides.

Intramolecular quenching of tryptophan fluorescence by protein functional groups was studied in a series of rigid cyclic hexapeptides containing a single tryptophan. The solution structure of the canonical peptide c[D-PpYTFWF] (pY, phosphotyrosine) was determined in aqueous solution by 1D- and 2D-(1)H NMR techniques. The peptide backbone has a single predominant conformation.