The evolution of bonded restorations has undergone great progress over several decades. Nonetheless, life spans of bonded restorations are limited mainly because of the eventual incidence of recurrent caries. Over time, water and waterborne agents (acids, enzymes) degrade the components of the dentin/restoration interface, allowing bacterial colonization and dentin reinfection at the margins of the restoration. We developed a 2-tier protective technology consisting of priming/coating dentin with amphipathic and antimicrobial peptides (AAMPs) to obtain hydrophobic/water-repellent and antibiofilm dentin-resisting recurrent caries around bonded restorations. We tested a series of AAMPs to assess their structure-function relationships as well as the effects of different dentin-conditioning methods on the structural features of AAMP-coated dentin. We found relation between the secondary structure of AAMPs (high portion of β-sheet), the antimicrobial potency of AAMPs, and the AAMPs’ ability to form hydrophobic coatings on dentin. We also determined that AAMPs had preferential adsorption on the mineral phase of dentin, which suggested that peptides arrange their cationic and hydrophilic motifs in direct contact with the negatively charged minerals in the hydrophilic dentin. These results led us to explore different dentin-conditioning methods that would increase the mineral/collagen ratio and their effect on AAMP immobilization. We innovatively imaged the spatial distribution of the AAMPs in relation to the dentinal tubules and collagen network using a minimally invasive multimodal imaging technique: multiphoton–second harmonic generation. Using multiphoton–second harmonic generation imaging, we determined that partial deproteinization of dentin increased the amount of immobilized AAMPs as compared with the total etched dentin at the dentin surface and extended deeply around dentinal tubules. Last, we analyzed the release rate of AAMPs from dentin coatings in artificial saliva to predict their stability in the clinical setting. In conclusion, priming dentin with AAMPs is a versatile new approach with potential to fortify the otherwise vulnerable adhesive-based interfaces.

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A methionine-rich 10 kDa zein storage protein from maize was isolated and the sequence of the N-terminal 30 amino acids was determined. Based on the amino acid sequence, two mixed oligonucleotides were synthesized and used to probe a maize endosperm cDNA library. A full-length cDNA clone encoding the 10 kDa zein was isolated by this procedure. The nucleotide sequence of the cDNA clone predicts a polypeptide of 129 amino acids, preceded by a signal peptide of 21 amino acids. The predicted polypeptide is unique in its extremely high content of methionine (22.5%). The maize inbred line BSSS-53, which has increased seed methionine due to overproduction of this protein, was compared to W23, a standard inbred line. Northern blot analysis showed that the relative RNA levels for the 10 kDa zein were enhanced in developing seeds of BSSS-53, providing a molecular basis for the overproduction of the protein. Southern blot analysis indicated that there are one or two 10 kDa zein genes in the maize genome.

Message levels for a methionine-rich 10 kDa zein were determined in three inbred lines of maize and their reciprocal crosses at various stages during endosperm development. Inbred line BSSS-53, which overexpresses the 10 kDa protein in mature kernels, was shown to have higher mRNA levels in developing endosperm, as compared to inbred lines W23 and W64A. Differences in mRNA levels could not be explained by differences in transcription rate of the 10 kDa zein gene, indicating differential post-transcriptional regulation of this storage protein in the different inbred lines analyzed. Among progeny segregating for the BSSS-53 allele of the 10 kDa zein structural gene Zps10/(22), mRNA levels are independent of Zps10/(22) segregation, indicating that post-transcriptional regulation of mRNA levels takes place via a trans-acting mechanism. In the same progeny, mRNA levels are also independent of allelic segregation of the regulatory locus Zpr10/(22). Thus, the trans-acting factor encoded by Zpr10/(22) determines accumulation of 10 kDa zein at a translational or post-translational step. Multiple trans-acting factors are therefore involved in post-transcriptional regulation of the methionine-rich 10 kDa zein.

Experiments were conducted to determine the chromosomal location of the gene conditioning overproduction of a methionine-rich, 10-K zein in maize kernels of line BSSS53. In addition, the chromosomal location of the structural gene encoding the overproduced protein was determined. Whereas the structural gene, designated Zps10/(22), was found to be located on the long arm of chromosome 9 near the centromere, the locus regulating overproduction of the zein protein was mapped to the short arm of chromosome 4. This regulatory gene has been designated Zpr10/(22). Regulation of 10-K zein production by Zpr10/(22) is, therefore, via a trans-acting mechanism.

Apolipoprotein C1 (ApoC1) is a component of multiple lipoproteins where it performs a variety of roles in lipid metabolism and transport. ApoC1 exists as both full-length and truncated isoforms. Truncation of ApoC1 has been postulated to result from the action of dipeptidyl peptidase-4 (DPP-4), the target of a new class of diabetes drugs that includes sitagliptin phosphate. In this study, we sought to determine if oral administration of sitagliptin altered the proportion of ApoC1 isoforms circulating in humans. Results indicated a dramatic change in ApoC1 truncation, consistent with a high level of DPP-4 inhibition by sitagliptin.Funding: University of Minnesota, Minneapolis, MN, USA.Electronic supplementary materialThe online version of this article (doi:10.1007/s13300-015-0123-1) contains supplementary material, which is available to authorized users.

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