Regulatory aspects of N-linked glycoproteins

Activation of beta-adrenoreceptors in rat parotid acinar cells leads to copious exocrine protein secretion. Additionally, beta-adrenergic stimulation dramatically increases specific secretory protein synthesis and enhances N-linked glycosylation of secretory glycoproteins. Recently, efforts have been directed toward understanding the mechanisms underlying these biosynthetic events. We have been particularly interested in the receptor-mediated regulation of glycosylation. In this report, we evaluate available mechanistic information from the rat parotid gland and present initial data examining the ability of various regulatory agents to modulate N-linked glycosylation in enzymatically-dispersed cell aggregates from surgical specimens of human parotid glands. We conclude that glycosylation of human parotid N-linked glycoproteins may be regulated by extracellular signaling similar to that operative in the rat parotid gland.     

Kinetics and mechanism of hydroxyapatite crystal dissolution in weak acid buffers using the rotating disk method.

The model given in this report and the rotating disk method provide a useful combination in the study of dental enamel and hydroxyapatite dissolution kinetics. The present approach is a significant improvement over earlier studies, and both the ionic activity product that governs the dissolution reaction and the apparent surface dissolution reaction rate constant may be simultaneously obtained. Thus, these investigations have established the baseline for the dissolution rate studies under sink conditions. Concurrent studies, under conditions where the acidic buffer mediums are partially saturated with respect to hydroxyapatite have shown another dissolution site for hydroxyapatite that operates at a higher ionic activity product but has a much smaller apparent surface reaction rate constant. This has raised the question of whether the presence of this second site may interfere with the proper theoretical analysis of the experimental results obtained under sink conditions. A preliminary analysis of the two-site model has shown that the dissolution kinetics of hydroxyapatite under sink conditions is almost completely governed by the sink condition site (KHAP = 10(-124.5), k' = 174) established in this report. The difference between the predicted dissolution rate for the one-site model and the two-site model are generally of the order of 4 to 5% where the experiments are conducted under sink conditions and over the range of variables covered in the present study.     

An in vitro study of coronal microleakage around bonded amalgam coronal-radicular cores in endodontically treated molar teeth.

OBJECTIVE: The aim of this study was to compare the coronal microleakage of conventional and bonded amalgam coronal-radicular (Nayyar) restorations on endodontically treated molar teeth, because coronal seal is a major factor in the long-term success of endodontic treatment. METHOD AND MATERIALS: Forty extracted human molar teeth were root-filled and prepared for coronal-radicular amalgam restorations. Four groups of 10 teeth were restored with Tytin amalgam and Vitrebond, Superbond D Liner II, Panavia 21, or no adhesive agent. The teeth were placed in India ink for 1 week, and then demineralized and rendered transparent. The ink penetration was assessed with a coded scoring system. RESULTS: The bonded amalgam groups produced significantly less leakage than did the nonbonded group. No statistically significant differences in leakage were detected among the bonded amalgam groups. CONCLUSION: To prevent the reinfection of the endodontically treated molar, it may be preferable to restore the tooth immediately after obturation by employing a bonded amalgam coronal-radicular technique.     

Improving the oral health status of all Americans: roles and responsibilities of academic dental institutions: the report of the ADEA President's Commission

Academic dental institutions are the fundamental underpinning of the nation's oral health. Education, research, and patient care are the cornerstones of academic dentistry that form the foundation upon which the dental profession rises to provide care to the public. The oral health status of Americans has improved dramatically over the past twenty-five to thirty years. In his 2000 report on oral health, the Surgeon General acknowledges the success of the dental profession in improving the oral health status of Americans over the past twenty-five years, but he also juxtaposes this success to profound and consequential disparities in the oral health of Americans. In 2002, the American Dental Education Association brought together an ADEA President's Commission of national experts to explore the roles and responsibilities of academic dental institutions in improving the oral health status of all Americans. They have issued this report and made a variety of policy recommendations, including a Statement of Position, to the 2003 ADEA House of Delegates. The commission's work will help guide ADEA in such areas as: identifying barriers to oral health care, providing guiding principles for academic dental institutions, anticipating workforce needs, and improving access through a diverse workforce and the types of oral health providers, including full utilization of allied dental professionals and collaborations with colleagues from medicine.     

A comparison of two microcomputer-based programs for bibliographic retrieval and formatting

We evaluated two representative microcomputer-based programs for organizing a biomedical literature filing system. With a bibliography of 100 anesthetic references, a series of benchmark tests was developed to measure the speed and accuracy of typical searching, sorting, and formatting tasks. Each program performed the searching tasks accurately and at about the same speed. One program performed sorting without errors, provided the field order of the template used to enter references was unchanged. Both programs used punctuation files, that is, templates for controlling author presentation; punctuation to suit style requirements of individual journals; and order of particular fields, such as publisher and year of publication. Each program was able to format journal, book, and chapter references correctly, but the resulting output required some refining in a word processor. Both require a major time commitment to learn and to create custom punctuation files for journals not included in the predesigned punctuation files. Once mastered, both programs are quite competent at organizing reprints and formatting journal references.     

Sequencing of LRP2 Reveals Multiple Rare Variants Associated with Urinary Trefoil Factor-3

Novel biomarkers are being investigated to identify patients with kidney disease. We measured a panel of 13 urinary biomarkers in participants from the Offspring Cohort of the Framingham Heart Study. Using an Affymetrix chip with imputation to 2.5 M single-nucleotide polymorphisms (SNPs), we conducted a GWAS of these biomarkers (n=2640) followed by exonic sequencing and genotyping. Functional studies in zebrafish were used to investigate histologic correlation with renal function. Across all 13 biomarkers, there were 97 significant SNPs at three loci. Lead SNPs at each locus were rs6555820 (P=6.7×10⁻⁴⁹; minor allele frequency [MAF]=0.49) in HAVCR1 (associated with kidney injury molecule-1), rs7565788 (P=2.15×10⁻¹⁶; MAF=0.22) in LRP2 (associated with trefoil factor 3 [TFF3]), and rs11048230 (P=4.77×10⁻⁸; MAF=0.10) in an intergenic region near RASSF8 (associated with vascular endothelial growth factor). Validation in the CKDGen Consortium (n=67,093) showed that only rs7565788 at LRP2, which encodes megalin, was associated with eGFR (P=0.003). Sequencing of exons 16–72 of LRP2 in 200 unrelated individuals at extremes of urinary TFF3 levels identified 197 variants (152 rare; MAF<0.05), 31 of which (27 rare) were nonsynonymous. In aggregate testing, rare variants were associated with urinary TFF3 levels (P=0.003), and the lead GWAS signal was not explained by these variants. Knockdown of LRP2 in zebrafish did not alter the renal phenotype in static or kidney injury models. In conclusion, this study revealed common variants associated with urinary levels of TFF3, kidney injury molecule-1, and vascular endothelial growth factor and identified a cluster of rare variants independently associated with TFF3.Serum creatinine, as used in most GFR estimating equations, is the primary biomarker of CKD.¹ Creatinine has significant limitations as a biomarker. It is insensitive to early declines in kidney function, and there are important extrarenal factors that influence its concentration, thus increasing the potential for misclassification when it is used to diagnose renal disease.² As a result, novel biomarkers are being investigated that could allow earlier and more accurate diagnosis of CKD.³ It is likely, however, that these biomarkers also have non-GFR determinants, including genetic factors. For example, levels of cystatin C, a novel GFR biomarker, are known to be influenced by both nongenetic factors, such as adiposity and the metabolic syndrome,⁴ and the presence of specific genetic variants in the cystatin C-gene cluster.⁵Genome-wide association studies (GWAS) allow for the evaluation of genetic associations of biomarkers in an unbiased manner. These studies could illuminate previously unrecognized pathways for CKD pathogenesis, thus identifying new potential molecular targets for therapeutic intervention. Multiple variants have been identified in association with kidney function through GWAS,⁶ whereas a variant in CUBN encoding cubilin, a proximal tubular transport protein, has been associated with albuminuria.⁷ Recently, a GWAS identified a locus at PTGDS in association with another kidney biomarker, β-trace protein.⁸To gain additional insight into biologic pathways of renal function and kidney injury, we measured a panel of 13 urinary biomarkers in participants from the Framingham Heart Study (FHS) and performed a GWAS of their levels. Here, we report the primary results from these studies as well as follow-up work to identify whether rare variants in LRP2 are associated with levels of trefoil factor 3 (TFF3).     

Variation within the serotonin (5-HT) 5-HT2C receptor system aligns with vulnerability to cocaine cue reactivity

Cocaine dependence remains a challenging public health problem with relapse cited as a major determinant in its chronicity and severity. Environmental contexts and stimuli become reliably associated with its use leading to durable conditioned responses (‘cue reactivity'') that can predict relapse as well as treatment success. Individual variation in the magnitude and influence of cue reactivity over behavior in humans and animals suggest that cue-reactive individuals may be at greater risk for the progression to addiction and/or relapse. In the present translational study, we investigated the contribution of variation in the serotonin (5-HT) 5-HT_2C receptor (5-HT_2CR) system in individual differences in cocaine cue reactivity in humans and rodents. We found that cocaine-dependent subjects carrying a single nucleotide polymorphism (SNP) in the HTR2C gene that encodes for the conversion of cysteine to serine at codon 23 (Ser23 variant) exhibited significantly higher attentional bias to cocaine cues in the cocaine-word Stroop task than those carrying the Cys23 variant. In a model of individual differences in cocaine cue reactivity in rats, we identified that high cocaine cue reactivity measured as appetitive approach behavior (lever presses reinforced by the discrete cue complex) correlated with lower 5-HT_2CR protein expression in the medial prefrontal cortex and blunted sensitivity to the suppressive effects of the selective 5-HT_2CR agonist WAY163909. Our translational findings suggest that the functional status of the 5-HT_2CR system is a mechanistic factor in the generation of vulnerability to cocaine-associated cues, an observation that opens new avenues for future development of biomarker and therapeutic approaches to suppress relapse in cocaine dependence.     

Use of intercostal bupivacaine with epinephrine after surgery to decrease use of narcotics and duration of intubation.

BACKGROUND: Postoperative pain plays a significant part in the recovery of patients after open heart surgery. OBJECTIVE: To determine if the use of intercostal bupivacaine with epinephrine is associated with decreases in use of narcotics and intubation times after open heart surgery. METHODS: A randomly selected experimental group of 25 patients received injections of bupivacaine with epinephrine in the intercostal tissues before chest closure in open heart surgery. A control group of 22 patients received no bupivacaine, only standard care. Postoperative use of narcotics and intubation times were determined for both groups. RESULTS: Compared with the control group, the group given bupivacaine with epinephrine used significantly less narcotics (P=.008) and had significantly shorter intubation times (P=.003). CONCLUSION: Injection of intercostal bupivacaine with epinephrine before chest closure in open heart surgery decreases use of narcotics and length of intubation postoperatively, thus speeding up recovery times.