Dentin Bonding: SEM Comparison of the Resin-Dentin Interface in Primary and Permanent Teeth

Previous studies have suggested minor differences between primary and permanent teeth in terms of dentin composition and morphology. Other reports indicated lower bond strengths of resin composites to dentin of primary teeth compared with dentin of permanent teeth; however, no information is available regarding differences in the micromorphology of the resin-dentin interface that may explain these lower bond strengths. Therefore, the purpose of the present study was to compare primary and permanent teeth in terms of the thickness of the hybrid layer developed with two bonding systems. Our hypothesis was that bonding differences previously reported between primary and permanent dentin would be reflected in hybrid layer differences observable in SEM analyses. Twenty human extracted and non-carious teeth were divided into 4 groups: 5 primary and 5 permanent teeth restored with All-Bond 2/Bisfil P system; and 5 primary and 5 permanent teeth restored with Scotchbond Multi-Purpose/ZlOO. The sample area available on each tooth was divided for the two dentin conditioning times (7 and 15 sec). Measurements of hybrid layer thickness were performed by means of SEM at xl3,000. The results of this study indicated that the hybrid layer produced is significantly thicker in primary than in permanent teeth (p = 0.0001), suggesting that primary tooth dentin is more reactive to acid conditioning. No difference was observed in the hybrid layers produced by the two adhesive systems (p = 0.7920). The increased thickness of the hybrid layer in primary teeth (25 to 30%) and the subsequent lack of complete penetration of adhesive resin into previously demineralized dentin may contribute to the lower bond strengths to primary dentin reported in the literature. If a narrower hybrid layer more uniformly infused with resin is the goal of dentin bonding, it is concluded that a differentiated protocol for bonding to primary dentin (with shorter time for dentin conditioning) can be used as a means to reproduce the hybrid layer thickness seen in permanent teeth.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67017/2/10.1177_00220345960750061101.pd

Cytotoxic Interactive Effects of Dentin Bonding Components on Mouse Fibroblasts

Previous studies have shown a wide range of pulpal reactions to dentin bonding systems and a poor correlation between in vitro and in vivo toxicity of dentin bonding agents. Because dentin bonding agents are composed of multiple components which may diffuse through dentin, we hypothesized that these components may cause cytotoxicity through interactive (synergistic) effects. We investigated the cytotoxicities of four dentin bonding components-HEMA, Bis-GMA, TEGDMA, and UDMA-and interactive effects for three binary combinations of the dentin bonding components-HEMA and Bis-GMA, Bis-GMA and TEGDMA, and TEGDMA and UDMA. Cytotoxicities to Balb/c 3T3 mouse fibroblasts were measured by the MTT assay. Concentrations which caused 50% toxicity compared with controls (TC50 values) were compared, and the interactive effects were determined by evaluation of the differences between observed and expected MTT activities of the cells. The ranks of toxicity of the dentin bonding components in terms of TC50 values were as follows: Bis-GMA > UDMA > TEGDMA >>> HEMA (least toxic) after 24- and 72-hour exposures. As binary combinations, the three combinations of dentin bonding components interacted in three ways—synergism, additivism, and antagonism-which were influenced by the concentrations of both components. The longer period of exposure resulted in a significant increase in the cytotoxicity of the dentin bonding components and combinations. The findings indicate that both exposure time and the interactions between the dentin bonding components may be important parameters in determining the cytotoxicity of dentin bonding agents in vivo.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66489/2/10.1177_00220345950740091601.pd

Small lytic peptides escape the inhibitory effect of heparan sulfate on the surface of cancer cells

Several naturally occurring cationic antimicrobial peptides (CAPs), including bovine lactoferricin (LfcinB), display promising anticancer activities. These peptides are unaffected by multidrug resistance mechanisms and have been shown to induce a protective immune response against solid tumors, thus making them interesting candidates for developing novel lead structures for anticancer treatment. Recently, we showed that the anticancer activity by LfcinB was inhibited by the presence of heparan sulfate (HS) on the surface of tumor cells. Based on extensive structure-activity relationship studies performed on LfcinB, shorter and more potent peptides have been constructed. In the present study, we have investigated the anticancer activity of three chemically modified 9-mer peptides and the influence of HS and chondroitin sulfate (CS) on their cytotoxic activity. Various cell lines and red blood cells were used to investigate the anticancer activity and selectivity of the peptides. The cytotoxic effect of the peptides against the different cell lines was measured by use of a colorimetric MTT viability assay. The influence of HS and CS on their cytotoxic activity was evaluated by using HS/CS expressing and HS/CS deficient cell lines. The ability of soluble HS and CS to inhibit the cytotoxic activity of the peptides and the peptides’ affinity for HS and CS were also investigated. The 9-mer peptides displayed selective anticancer activity. Cells expressing HS/CS were equally or more susceptible to the peptides than cells not expressing HS/CS. The peptides displayed a higher affinity for HS compared to CS, and exogenously added HS inhibited the cytotoxic effect of the peptides. In contrast to the previously reported inhibitory effect of HS on LfcinB, the present study shows that the cytotoxic activity of small lytic peptides was increased or not affected by cell surface HS

Different Pattern of Immunoglobulin Gene Usage by HIV-1 Compared to Non-HIV-1 Antibodies Derived from the Same Infected Subject

A biased usage of immunoglobulin (Ig) genes is observed in human anti-HIV-1 monoclonal antibodies (mAbs) resulting probably from compensation to reduced usage of the VH3 family genes, while the other alternative suggests that this bias usage is due to antigen requirements. If the antigen structure is responsible for the preferential usage of particular Ig genes, it may have certain implications for HIV vaccine development by the targeting of particular Ig gene-encoded B cell receptors to induce neutralizing anti-HIV-1 antibodies. To address this issue, we have produced HIV-1 specific and non-HIV-1 mAbs from an infected individual and analyzed the Ig gene usage. Green-fluorescence labeled virus-like particles (VLP) expressing HIV-1 envelope (Env) proteins of JRFL and BaL and control VLPs (without Env) were used to select single B cells for the production of 68 recombinant mAbs. Ten of these mAbs were HIV-1 Env specific with neutralizing activity against V3 and the CD4 binding site, as well as non-neutralizing mAbs to gp41. The remaining 58 mAbs were non-HIV-1 Env mAbs with undefined specificities. Analysis revealed that biased usage of Ig genes was restricted only to anti-HIV-1 but not to non-HIV-1 mAbs. The VH1 family genes were dominantly used, followed by VH3, VH4, and VH5 among anti-HIV-1 mAbs, while non-HIV-1 specific mAbs preferentially used VH3 family genes, followed by VH4, VH1 and VH5 families in a pattern identical to Abs derived from healthy individuals. This observation suggests that the biased usage of Ig genes by anti-HIV-1 mAbs is driven by structural requirements of the virus antigens rather than by compensation to any depletion of VH3 B cells due to autoreactive mechanisms, according to the gp120 superantigen hypothesis

Back to the sea twice: identifying candidate plant genes for molecular evolution to marine life

Background: Seagrasses are a polyphyletic group of monocotyledonous angiosperms that have adapted to a completely submerged lifestyle in marine waters. Here, we exploit two collections of expressed sequence tags (ESTs) of two wide-spread and ecologically important seagrass species, the Mediterranean seagrass Posidonia oceanica (L.) Delile and the eelgrass Zostera marina L., which have independently evolved from aquatic ancestors. This replicated, yet independent evolutionary history facilitates the identification of traits that may have evolved in parallel and are possible instrumental candidates for adaptation to a marine habitat. Results: In our study, we provide the first quantitative perspective on molecular adaptations in two seagrass species. By constructing orthologous gene clusters shared between two seagrasses (Z. marina and P. oceanica) and eight distantly related terrestrial angiosperm species, 51 genes could be identified with detection of positive selection along the seagrass branches of the phylogenetic tree. Characterization of these positively selected genes using KEGG pathways and the Gene Ontology uncovered that these genes are mostly involved in translation, metabolism, and photosynthesis. Conclusions: These results provide first insights into which seagrass genes have diverged from their terrestrial counterparts via an initial aquatic stage characteristic of the order and to the derived fully-marine stage characteristic of seagrasses. We discuss how adaptive changes in these processes may have contributed to the evolution towards an aquatic and marine existence

Membrane Bridging and Hemifusion by Denaturated Munc18

Neuronal Munc18-1 and members of the Sec1/Munc18 (SM) protein family play a critical function(s) in intracellular membrane fusion together with SNARE proteins, but the mechanism of action of SM proteins remains highly enigmatic. During experiments designed to address this question employing a 7-nitrobenz-2-oxa-1,3-diazole (NBD) fluorescence de-quenching assay that is widely used to study lipid mixing between reconstituted proteoliposomes, we observed that Munc18-1 from squid (sMunc18-1) was able to increase the apparent NBD fluorescence emission intensity even in the absence of SNARE proteins. Fluorescence emission scans and dynamic light scattering experiments show that this phenomenon arises at least in part from increased light scattering due to sMunc18-1-induced liposome clustering. Nuclear magnetic resonance and circular dichroism data suggest that, although native sMunc18-1 does not bind significantly to lipids, sMunc18-1 denaturation at 37°C leads to insertion into membranes. The liposome clustering activity of sMunc18-1 can thus be attributed to its ability to bridge two membranes upon (perhaps partial) denaturation; correspondingly, this activity is hindered by addition of glycerol. Cryo-electron microscopy shows that liposome clusters induced by sMunc18-1 include extended interfaces where the bilayers of two liposomes come into very close proximity, and clear hemifusion diaphragms. Although the physiological relevance of our results is uncertain, they emphasize the necessity of complementing fluorescence de-quenching assays with alternative experiments in studies of membrane fusion, as well as the importance of considering the potential effects of protein denaturation. In addition, our data suggest a novel mechanism of membrane hemifusion induced by amphipathic macromolecules that does not involve formation of a stalk intermediate

The anticancer activity of lytic peptides is inhibited by heparan sulfate on the surface of the tumor cells

<p>Abstract</p> <p>Background</p> <p>Cationic antimicrobial peptides (CAPs) with antitumor activity constitute a promising group of novel anticancer agents. These peptides induce lysis of cancer cells through interactions with the plasma membrane. It is not known which cancer cell membrane components influence their susceptibility to CAPs. We have previously shown that CAPs interact with the two glycosaminoglycans (GAGs), heparan sulfate (HS) and chondroitin sulfate (CS), which are present on the surface of most cells. The purpose of this study was to investigate the role of the two GAGs in the cytotoxic activity of CAPs.</p> <p>Methods</p> <p>Various cell lines, expressing different levels of cell surface GAGs, were exposed to bovine lactoferricin (LfcinB) and the designer peptide, KW5. The cytotoxic effect of the peptides was investigated by use of the colorimetric MTT viability assay. The cytotoxic effect on wild type CHO cells, expressing normal amounts of GAGs on the cell surface, and the mutant pgsA-745, that has no expression of GAGs on the cell surface, was also investigated.</p> <p>Results</p> <p>We show that cells not expressing HS were more susceptible to CAPs than cells expressing HS at the cell surface. Further, exogenously added heparin inhibited the cytotoxic effect of the peptides. Chondroitin sulfate had no effect on the cytotoxic activity of KW5 and only minor effects on LfcinB cytotoxicity.</p> <p>Conclusion</p> <p>Our results show for the first time that negatively charged molecules at the surface of cancer cells inhibit the cytotoxic activity of CAPs. Our results indicate that HS at the surface of cancer cells sequesters CAPs away from the phospholipid bilayer and thereby impede their ability to induce cytolysis.</p

Global variation in diabetes diagnosis and prevalence based on fasting glucose and hemoglobin A1c

Fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) are both used to diagnose diabetes, but these measurements can identify different people as having diabetes. We used data from 117 population-based studies and quantified, in different world regions, the prevalence of diagnosed diabetes, and whether those who were previously undiagnosed and detected as having diabetes in survey screening, had elevated FPG, HbA1c or both. We developed prediction equations for estimating the probability that a person without previously diagnosed diabetes, and at a specific level of FPG, had elevated HbA1c, and vice versa. The age-standardized proportion of diabetes that was previously undiagnosed and detected in survey screening ranged from 30% in the high-income western region to 66% in south Asia. Among those with screen-detected diabetes with either test, the age-standardized proportion who had elevated levels of both FPG and HbA1c was 29–39% across regions; the remainder had discordant elevation of FPG or HbA1c. In most low- and middle-income regions, isolated elevated HbA1c was more common than isolated elevated FPG. In these regions, the use of FPG alone may delay diabetes diagnosis and underestimate diabetes prevalence. Our prediction equations help allocate finite resources for measuring HbA1c to reduce the global shortfall in diabetes diagnosis and surveillance

Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants

Background: Hypertension can be detected at the primary health-care level and low-cost treatments can effectively control hypertension. We aimed to measure the prevalence of hypertension and progress in its detection, treatment, and control from 1990 to 2019 for 200 countries and territories.Methods: We used data from 1990 to 2019 on people aged 30-79 years from population-representative studies with measurement of blood pressure and data on blood pressure treatment. We defined hypertension as having systolic blood pressure 140 mm Hg or greater, diastolic blood pressure 90 mm Hg or greater, or taking medication for hypertension. We applied a Bayesian hierarchical model to estimate the prevalence of hypertension and the proportion of people with hypertension who had a previous diagnosis (detection), who were taking medication for hypertension (treatment), and whose hypertension was controlled to below 140/90 mm Hg (control). The model allowed for trends over time to be non-linear and to vary by age.Findings: The number of people aged 30-79 years with hypertension doubled from 1990 to 2019, from 331 (95% credible interval 306-359) million women and 317 (292-344) million men in 1990 to 626 (584-668) million women and 652 (604-698) million men in 2019, despite stable global age-standardised prevalence. In 2019, age-standardised hypertension prevalence was lowest in Canada and Peru for both men and women; in Taiwan, South Korea, Japan, and some countries in western Europe including Switzerland, Spain, and the UK for women; and in several low-income and middle-income countries such as Eritrea, Bangladesh, Ethiopia, and Solomon Islands for men. Hypertension prevalence surpassed 50% for women in two countries and men in nine countries, in central and eastern Europe, central Asia, Oceania, and Latin America. Globally, 59% (55-62) of women and 49% (46-52) of men with hypertension reported a previous diagnosis of hypertension in 2019, and 47% (43-51) of women and 38% (35-41) of men were treated. Control rates among people with hypertension in 2019 were 23% (20-27) for women and 18% (16-21) for men. In 2019, treatment and control rates were highest in South Korea, Canada, and Iceland (treatment >70%; control >50%), followed by the USA, Costa Rica, Germany, Portugal, and Taiwan. Treatment rates were less than 25% for women and less than 20% for men in Nepal, Indonesia, and some countries in sub-Saharan Africa and Oceania. Control rates were below 10% for women and men in these countries and for men in some countries in north Africa, central and south Asia, and eastern Europe. Treatment and control rates have improved in most countries since 1990, but we found little change in most countries in sub-Saharan Africa and Oceania. Improvements were largest in high-income countries, central Europe, and some upper-middle-income and recently high-income countries including Costa Rica, Taiwan, Kazakhstan, South Africa, Brazil, Chile, Turkey, and Iran.Interpretation: Improvements in the detection, treatment, and control of hypertension have varied substantially across countries, with some middle-income countries now outperforming most high-income nations. The dual approach of reducing hypertension prevalence through primary prevention and enhancing its treatment and control is achievable not only in high-income countries but also in low-income and middle-income settings.Copyright (C) 2021 World Health Organization; licensee Elsevier.</p