Interdisciplinary management of a maxillary central incisor with a palato-radicular groove: A case report with 27 years follow-up.

OBJECTIVE: The palato-radicular groove (PRG) is caused by a developmental anomaly, genetically determined, whereby an in-folding of the enamel organ and Hertwig's epithelial root sheath occurs. The depth and length of the groove determine the prognosis for the tooth. The interdisciplinary team formulated a treatment plan to save this tooth for this 8-year-old patient. The goal was to prolong the life of the tooth until his growth was completed and a more permanent tooth replacement could be considered if the tooth failed. CLINICAL CONSIDERATIONS: This patient had #8 with a very deep palatal groove extending from the CEJ to the apex of the tooth, causing a 12 mm periodontal pocket with suppuration. Endodontic treatment, periodontal regeneration, and orthodontics were done to prolong the life of the tooth and preserve the bone for future tooth replacement if the tooth failed and needed to be extracted. The tooth survived for 11 years before the pocketing recurred due to the deep groove. The tooth was extracted and replaced with an implant. CONCLUSION: Teeth with a PRG present multiple challenges depending on the depth and length of the groove. An accurate diagnosis of the endodontic and periodontal status of the tooth is critical. Teeth with very long and deep grooves make the case more difficult to treat endodontically and periodontally. The tooth had a very poor prognosis; however, it was saved for an extended period of time with a well thought out interdisciplinary treatment plan. The advantages of maintaining this tooth, in lieu of extraction at age 8, will be elucidated. CLINICAL SIGNIFICANCE: Retaining guarded teeth in the maxillary esthetic zone for an 8-year-old patient, has many advantages. It can simplify and enhance future treatment results. The patient retained this central incisor through the formative years. It simplified the orthodontic treatment and implant treatment. The importance of keeping "roots in the bone" to preserve the alveolar bone has many advantages for future treatment options.

Modification of ventriculo-arterial coupling by spironolactone in nonischemic dilated cardiomyopathy.

AIMS: We sought to clarify the role of ventriculo-arterial (V-A) coupling in the treatment of nonischemic dilated cardiomyopathy (NIDCM) by adding a mineralocorticoid receptor antagonist (MRA) to conventional anti-failure therapy. METHODS AND RESULTS: We employed cardiac magnetic resonance imaging to quantify left ventricular (LV) contractility and V-A coupling in normal subjects at rest (n = 11) and in patients with NIDCM (n = 12) before and after long term anti-failure therapy, in which MRA was added to conventional anti-failure therapy. After ≥6 months' treatment in NIDCM patients, LV volumes and mass decreased, and the LV ejection fraction increased from a median of 24% (17, 27) (interquartile range IQR) to 47 (42, 52) (P < 0.002), with a marked reduction in arterial elastance (Ea) from 2.89 mmHg/mL (2.34, 4.0) to 1.50 (1.29, 1.95) (P < 0.002), similar to Ea of normal subjects, 1.53 (1.34, 1.67) (P > 0.05). The V-A coupling ratio, Ea/end-systolic elastance (single-beat method), decreased by -1.08 (-1.96, -0.55), (P = 0.003), as did Ea/end-systolic pressure/end-systolic pressure ratio, -0.54 (0.35, 0.87), (P = 0.002). The preload recruitable stroke work (PRSW) increased as did PRSW indexed for Ea (both P = 0.002), which reflected 'total circulatory performance'. CONCLUSIONS: In NIDCM, adding MRA to conventional anti-failure therapy markedly improved LV ejection fraction and reduced peripheral vascular resistance, due to both improved LV contractility and especially to enhanced V-A coupling, as Ea decreased to normal. Total circulatory performance was a sensitive indicator of both LV pump performance and the arterial loading conditions.

The thermodynamics of the self-assembly of covalently linked oligomeric naphthalenediimides into helical organic nanotubes.

The mechanism and thermodynamic functions of the self-assembly of a family of covalently linked oligomeric naphthalenediimides (NDIs) were investigated through variable-temperature NMR and CD studies. The NDIs were shown to self-assemble into helical supramolecular nanotubes via an isodesmic polymerisation mechanism, and regardless of the oligomer length a surprising entropy-enthalpy compensation was observed.

Rapid cleavage of unactivated, unstrained amide bonds at neutral pH.

Building upon the discovery of Suggs and Pires that N-(2-hydroxyethyl)glycine amides undergo rapid amide cleavage under mild conditions [ Suggs, J. W. ; Pires, R. M. Tetrahedron Lett. 1997, 38, 2227-2230 ], we synthesized the derivatives (4aalpha,8beta,8aalpha)-1-ethylamido-8-hydroxydecahydroquinoline ( 4) and (4aalpha,8alpha,8abeta)-1-ethylamido-8-hydroxydecahydroquinoline ( 5). These two species are conformationally constrained, but steric compression is not introduced between the hydroxyl group and the amide functionality it attacks. At 20 degrees C and slightly basic pH, derivatives 4 and 5 undergo amide cleavage with half-lives of 21 min and 14 h, respectively, which correspond to rate increases of 251- and 6.3-fold relative to the acyclic analogue N-(2-hydroxyethyl)glycine amide ( 3).

Recent developments in the molecular imprinting of proteins.

Molecular imprinting is an inexpensive method for the rapid fabrication of organic polymeric and inorganic network-structured materials that selectively bind a template molecule--in other words, materials that function as artificial antibodies. Imprints against small-molecule templates have been generated for decades, but attempts to prepare imprints against proteins have, until recently, been far less successful. The field has progressed rapidly, however, and a number of molecular imprints selective for protein ligands have now been reported. Given the enormous potential of replacing the antibodies used in a host of immunoassays with robust and inexpensive receptors, efforts in this area continue to intensify. This review begins with a brief analysis of two naturally occurring protein-ligand complexes, each of which illustrates the specific interactions essential for precise molecular recognition. Key developments--all appearing in 2006 and 2007--in the molecular imprinting of proteins, including many impressive advances, are then discussed.

Amide bond cleavage: acceleration due to a 1,3-diaxial interaction with a carboxylic acid.

To independently assess the contribution of ground-state pseudoallylic strain to the enormous rates of amide bond cleavage in tertiary amide derivatives of Kemp's triacid, we have studied four amide derivatives of (1alpha-3alpha-5beta)-5-tert-butyl-1,3-cyclohexanedicarboxylic acid. Our results demonstrate that absent pseudoallylic strain, a 1,3-diaxial interaction of an amide with a carboxylic acid leads to only a 2400-fold increase in the rate of amide bond cleavage as compared with the rate of hydrolysis of an unactivated peptide bond.

Glucose-specific poly(allylamine) hydrogels--a reassessment.

Polymer hydrogels synthesized by crosslinking poly(allylamine hydrochloride) with (+/-)-epichlorohydrin in the presence of d-glucose-6-phosphate monobarium salt do not show imprinting on the molecular level. A series of hydrogels was prepared using the following five templates: d-glucose-6-phosphate monobarium salt, d-glucose, l-glucose, barium hydrogen phosphate (BaHPO(4)), and d-gluconamide; a hydrogel was also prepared in the absence of a template. For all six hydrogels, batch binding studies were conducted with d-glucose, l-glucose, d-fructose, and d-gluconamide. The extent of analyte sugar binding was determined using (1)H NMR. Each hydrogel shows approximately the same relative binding affinity for the different sugar derivatives, and none displays selectivity for either glucose enantiomer. The results of the binding studies correlate with the octanol-water partition coefficients of the sugars, indicative that differential solubilities in the bulk polymer account for the binding affinities observed. Thus, in contrast to templated hydrogels prepared using methacrylate- or acrylamide-based reagents, true imprinting does not occur in this novel, crosslinked-poly(allylamine hydrochloride) system.

Genetic and fluorescence studies of affinity maturation in related antibodies.

Affinity maturation, the process by which an organism's response to infection becomes more specific and more effective over time, occurs after somatic hypermutation of antibody genes in B-cells. This increase in affinity might be a result of the evolution of either specific interactions between antigen and antibody over time (enthalpic factors) or antibody binding site rigidification (entropic factors) or both. Here, monoclonal antibodies, derived from antibodies elicited at different points in the murine immune response after inoculation with the same diketone hapten, have been characterized both genetically and functionally. Though this hapten has previously been shown to produce the catalytic aldolase antibody 38C2, antibodies described here are not catalytic and unlike 38C2, form no covalent enzyme-substrate complex. Thus, they provide a system in which to assess contributions to the evolution of binding affinity. The genes for these non-catalytic antibodies have been sequenced and analyzed both with regard to their relationships to germ line genes, to each other, and to two commercially available catalytic aldolase antibodies. Consequences of particular mutations for antigen binding behavior are discussed. The protein products of these genes have been expressed, purified, and binding properties measured by two complementary techniques: the hapten-induced quenching of the native antibody fluorescence and the changes in the anisotropy of Prodan (6-propionyl-2-(dimethylamino)naphthalene), a fluorescent hapten analogue. Differences in binding affinity are related back to differences in the lengths and amino acid sequences of the complementary determining region 3 (CDR3) binding loop. Taken together with our earlier results on binding site heterogeneity from tryptophan lifetime analysis [Mohan, G.S., Chiu, P.T., Southern, C.A., O'Hara, P.B., 2004. Steady-state and multifrequency phase fluorometry studies of binding site flexibility in related antibodies. J. Phys. Chem. A 108, 7871-7877], affinity appears to be modulated by a combination of entropic and enthalpic factors, and not dominated by one or the other. Because these antibodies are not related to the same germ line gene, however, these results do not provide evidence for the dominance of enthalpy or entropy in evolving binding affinity in this system.

Rapid cleavage of cyclic tertiary amides of Kemp's triacid: effects of ring structure.

The piperidyl and prolyl amides of Kemp's triacid (7 and 8, respectively) have been prepared and their rates of intramolecular acylolysis measured as a function of pD. The piperidyl derivative 7 reacts approximately four-times faster (e.g., t(1/2)=3 min at 20 degrees C and pD7.7) than the previously reported pyrrolidyl and methylphenethyl amide derivatives, while the prolyl derivative 8 reacts two-times more slowly (e.g., e.g., t(1/2)=30 min at 20 degrees C and pD7.8). Molecular-mechanics calculations indicate that the nonbonded interactions in the piperidyl derivative 7 are distinct from those in the prolyl, pyrrolidyl, and methylphenethyl amide derivatives, a result that supports the suggestion that ground-state pseudoallylic strain contributes to the enormous reactivity of Kemp's triacid tertiary amides. In sum, the results reported indicate that the Kemp's triacid scaffolding provides a general means of activating tertiary amide derivatives.

Stretch-induced ventricular arrhythmias during acute ischemia and reperfusion.

Mechanical stretch has been demonstrated to have electrophysiological effects on cardiac muscle, including alteration of the probability of excitation, alteration of the action potential waveform, and stretch-induced arrhythmia (SIA). We demonstrate that regional ventricular ischemia due to coronary artery occlusion increases arrhythmogenic effects of transient diastolic stretch, whereas globally ischemic hearts showed no such increase. We tested our hypothesis that, during phase Ia ischemia, regionally ischemic hearts may be more susceptible to triggered arrhythmogenesis due to transient diastolic stretch. During the first 20 min of regional ischemia, the probability of eliciting a ventricular SIA (P(SIA)) by transient diastolic stretch increased significantly. However, after 30 min, P(SIA) decreased to a value comparable with baseline measurements, as expected during phase Ib, where most ventricular arrhythmias are of reentrant mechanisms. We also suggest that mechanoelectrical coupling may contribute to the nonreentrant mechanisms underlying reperfusion-induced arrhythmia. When coronary artery occlusion was relieved after 30 min of ischemia, we observed an increase in P(SIA) and the maintenance of this elevated level throughout 20 min of reperfusion. We conclude that mechanoelectrical coupling may underlie triggered arrhythmogenesis during phase 1a ischemia and reperfusion.