Enamel Proteases in Secretory and Maturation Enamel of Rats Ingesting 0 and 100 ppm Fluoride in Drinking Water

1989 ◽  
Vol 3 (2) ◽  
pp. 199-202 ◽  
Author(s):  
P.K. Denbesten ◽  
L.M. Heffernan

Dental enamel formed during ingestion of high levels of fluoride in drinking water has an increased organic content in the maturation stage, which may be due to a delay in the breakdown of amelogenins during the early-maturation stage of enamel formation. This delay in the breakdown of amelogenins in fluorosed enamel suggests an effect of fluoride on enamel proteases which hydrolyze the early secreted enamel proteins. In this study, we compared the proteases present in fluorosed and control secretory-stage and maturation-stage enamel. Enamel was demineralized and separated in SDS gels containing 0.1% gelatin. After incubation in 100 mmol/L Tris-HCI, pH 8, with 10 mmol/L CaCl2, the gels were stained with Coomassie Blue, and proteases were seen as clear zones of degraded gelatin. Similar bands of proteolytic activity were seen in fluorosed and in control enamel. In the maturation stage, more proteases were present than in the secretory stage of enamel formation. Less digestion of gelatin substrate occurred in several proteases found in the fluorosed maturation-stage enamel as compared with the control maturation-stage enamel. This suggests that the amount of protease secreted or the activity of the proteases may be altered in fluorosed maturation-stage enamel.

2008 ◽  
Vol 389 (6) ◽  
Author(s):  
Yuhe Lu ◽  
Petros Papagerakis ◽  
Yasuo Yamakoshi ◽  
Jan C.-C. Hu ◽  
John D. Bartlett ◽  
...  

Abstract Two proteases are secreted into the enamel matrix of developing teeth. The early protease is enamelysin (MMP-20). The late protease is kallikrein 4 (KLK4). Mutations in MMP20 and KLK4 both cause autosomal recessive amelogenesis imperfecta, a condition featuring soft, porous enamel containing residual protein. MMP-20 is secreted along with enamel proteins by secretory-stage ameloblasts. Enamel protein-cleavage products accumulate in the space between the crystal ribbons, helping to support them. MMP-20 steadily cleaves accumulated enamel proteins, so their concentration decreases with depth. KLK4 is secreted by transition- and maturation-stage ameloblasts. KLK4 aggressively degrades the retained organic matrix following the termination of enamel protein secretion. The principle functions of MMP-20 and KLK4 in dental enamel formation are to facilitate the orderly replacement of organic matrix with mineral, generating an enamel layer that is harder, less porous, and unstained by retained enamel proteins.


1987 ◽  
Vol 1 (2) ◽  
pp. 176-180 ◽  
Author(s):  
P.K. Denbesten ◽  
M.A. Crenshaw

Exposure to chronic high levels of fluoride results in the formation of fluorosed enamel. Although enamel may be more susceptible to fluorotic effects at certain stages of development, fluoride at sufficiently high levels may affect enamel at all stages of formation. Careful study of the changes in enamel caused by chronic fluoride ingestion is needed to understand more fully the mechanisms involved in the formation of fluorotic enamel. This paper discusses the various studies we have completed to define the changes, in developing enamel of the rat incisor, caused by long-term ingestion of fluoride in drinking water. Fluoride has been found to inhibit secretion of enamel proteins. Changes in the maturation stage of enamel formation include the retention of amelogenin proteins during early maturation. The various mechanisms which have been investigated in the formation of fluorosed enamel include a direct effect of fluoride on the enamel organ, and specific interactions of fluoride with the extracellular enamel matrix. Although the same amount of protease appears to be secreted in fluorosed and control enamel, a delay in the digestion of amelogenin protein occurs. This suggests that fluoride may directly or indirectly inhibit the protease present in fluorosed enamel to slow the proteolysis of amelogenins.


1989 ◽  
Vol 37 (11) ◽  
pp. 1619-1633 ◽  
Author(s):  
A Nanci ◽  
J P Ahluwalia ◽  
S Zalzal ◽  
C E Smith

Biochemical and histochemical studies have shown the presence of various carbohydrates in enamel. Using lectin-gold cytochemistry, we have examined the distribution of glycoconjugates containing N-acetyl-D-galactosamine (GalNAc) and/or N-acetyl-glucosamine (GlcNAc)/N-acetyl-neuraminic acid (NeuNAc) residues in rat incisor ameloblasts and in forming and maturing enamel embedded in Lowicryl K4M, LR Gold, and LR White resins. The enamel proteins that contain these carbohydrate moieties were further characterized by lectin blotting. All three resins allowed, albeit to a variable degree, detection of the binding sites for Helix pomatia agglutinin (HPA) and wheat germ agglutinin (WGA) GalNAc, and GlcNAc/NeuNAc, respectively. In general, Lowicryl K4M permitted more intense reactions with both lectins. Lectin binding was observed over the rough endoplasmic reticulum (weak labeling with WGA), the Golgi apparatus, lysosomes, secretory granules, and the enamel matrix. These compartments were shown by double labeling with WGA and anti-amelogenin antibody, and by previous immunocytochemical studies, to contain enamel proteins. Furthermore, WGA binding was more concentrated at the growth sites of enamel. Lectin blotting showed that several proteins in the amelogenin group were glycosylated and contained the sugars GalNAc and GlcNAc/NeuNAc. Fewer proteins were stained by HPA than by WGA, and the staining pattern suggested that the extracellular proteins recognized by these two lectins are processed differently. The HPA-reactive proteins were lost by or during the early maturation stage, whereas many of the WGA-reactive proteins persisted into the mid maturation stage. The heterogeneous staining of certain protein bands observed with WGA suggests that they contain more than one component. Two distinct glycoproteins containing GlcNAc/NeuNAc also appeared during the maturation stage. These results are consistent with the notion that ameloblasts produce an extracellular matrix composed mainly of glycosylated amelogenins which are differently processed throughout amelogenesis.


2005 ◽  
Vol 84 (12) ◽  
pp. 1117-1126 ◽  
Author(s):  
G. Stephanopoulos ◽  
M.-E. Garefalaki ◽  
K. Lyroudia

Dental enamel formation is a remarkable example of a biomineralization process. The exact mechanisms involved in this process remain partly obscure. Some of the genes encoding specific enamel proteins have been indicated as candidate genes for amelogenesis imperfecta. Mutational analyses within studied families have supported this hypothesis. Mutations in the amelogenin gene ( AMELX) cause X-linked amelogenesis imperfecta, while mutations in the enamelin gene ( ENAM) cause autosomal-inherited forms of amelogenesis imperfecta. Recent reports involve kallikrein-4 ( KLK4), MMP-20, and DLX3 genes in the etiologies of some cases. This paper focuses mainly on the candidate genes involved in amelogenesis imperfecta and the proteins derived from them, and reviews current knowledge on their structure, localization within the tissue, and correlation with the various types of this disorder.


1999 ◽  
Vol 10 (4) ◽  
pp. 425-441 ◽  
Author(s):  
J.D. Bartlett ◽  
J.P. Simmer

For almost three decades, proteinases have been known to reside within developing dental enamel. However, identification and characterization of these proteinases have been slow and difficult, because they are present in very small quantities and they are difficult to purify directly from the mineralizing enamel. Enamel matrix proteins such as amelogenin, ameloblastin, and enamelin are cleaved by proteinases soon after they are secreted, and their cleavage products accumulate in the deeper, more mature enamel layers, while the full-length proteins are observed only at the surface. These results suggest that proteinases are necessary for "activating" enamel proteins so the parent proteins and their cleavage products may perform different functions. A novel matrix metalloproteinase named enamelysin (MMP-20) was recently cloned from tooth tissues and was later shown to localize primarily within the most recently formed enamel. Furthermore, recombinant porcine enamelysin was demonstrated to cleave recombinant porcine amelogenin at virtually all of the sites that have previously been described in vivo. Therefore, enamelysin is at least one enzyme that may be important during early enamel development. As enamel development progresses to the later stages, a profound decrease in the enamel protein content is observed. Proteinases have traditionally been assumed to degrade the organic matrix prior to its removal from the enamel. Recently, a novel serine proteinase named enamel matrix serine proteinase-1 (EMSP1) was cloned from enamel organ epithelia. EMSP1 localizes primarily to the early maturation stage enamel and may, therefore, be involved in the degradation of proteins prior to their removal from the maturing enamel. Other, as yet unidentified, proteinases and proteinase inhibitors are almost certainly present within the forming enamel and await discovery.


2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 153-154
Author(s):  
Yuzhi Li ◽  
Yunhui Zhu ◽  
Michael Reese ◽  
Eric Buchanan ◽  
Lee Johnston

Abstract This study was conducted to evaluate effects of chilled drinking water and cooled floor pads on behavior of lactating sows under heat stress. Sows were housed in individual farrowing stalls in two rooms with temperatures being controlled at 29.4°C (0700h to 1900h) and 23.9°C (1900h to 0700h). Sows in one room (treatment), but not in the other room (control) were provided with chilled drinking water (13 to 15°C) and cooled floor pads (15 to 18°C). Behavior of sows (n=15 sows/treatment; parity=1 to 6) was video recorded during farrowing, and d 1, 3, 7, 14, and 21 after farrowing. Videos were viewed to register birth time of each piglet. Number of drinking bouts and duration of each bout were registered for 2 h (1530h to 1730h) each day after farrowing. Postures (lying laterally, lying ventrally, sitting, and standing) were recorded by scanning video-recordings at 5-min intervals for 24 h each day after farrowing, and time budget for each posture was calculated. Data were analyzed using the Glimmix Procedure of SAS. No effect of treatment was detected for litter size born, farrowing duration, or birth interval (P >0.33; Table 1). Neither frequency nor duration of drinking bouts was affected by treatment (P >0.27). No significant difference was observed in time budget for each posture (P >0.46) between treatment and control groups. As lactation progressed, sows increased drinking frequency (from 1.2 drinks/2h on d 1 to 4.9 drinks/2h on d 21; P< 0.001) and time spent lying ventrally (8% to 14%; P< 0.0001), standing (4% to 10%; P< 0.001), and sitting (2% to 4%; P< 0.0001), and decreased time spent lying laterally (86% to 67%; P< 0.0001) in both control and treatment rooms. These results indicate that chilled drinking water and cooled floor pads did not affect behavior of sows during farrowing and lactation in the current study.


2021 ◽  
pp. 116964
Author(s):  
Yunkun Qian ◽  
Yanan Chen ◽  
Yue Hu ◽  
David Hanigan ◽  
Paul Westerhoff ◽  
...  

Coatings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 549 ◽  
Author(s):  
Bruna Sinjari ◽  
Gianmaria D’Addazio ◽  
Martina Bozzi ◽  
Manlio Santilli ◽  
Tonino Traini ◽  
...  

The aim of this in vitro study was to evaluate the enamel surface topography after treatment with three air polishing powders: Glycine (A), erythritol (B), and sodium bicarbonate (C) (Air Flow Soft, Plus and Classic powders, EMS Electro Medical Systems S.A., Nyon, Switzerland). Fifteen extracted incisors were randomly divided into three groups of five teeth each, A, B and C, respectively. The teeth were blocked in plaster bases, washed, dried and half-covered with polytetrafluoroethylene strips before treatment. In this way, each half-treated dental element became test and control of itself. Comparative statistical analysis of Rq (geometric average of the deviations occurring in roughness profile) was performed. The scanning electron microscope (SEM) analysis showed different degrees of surface roughness between the groups, decreasing after treatment. In addition, a statistically significant reduction p < 0.05 was present in group C (Rq mean non-treated 108.17 µm, 95% CI: 97.29–124.01 and Rq mean treated 86.78 µm, 95% CI: 80.63–93.70). A decrease in surface roughness post-treatment was not observed in group A and B. Therefore, it may be concluded that the air flow powders tested herein can be used on dental enamel to reduce the surface roughness due to function and the action of dental therapies.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Momoko Ueda ◽  
Lynne S. Bell

AbstractStable isotope analysis of human tissues has become a valuable tool for mapping human geolocation. This study adds to the existing knowledge of the relationship between oxygen stable isotopes in human enamel and drinking water by presenting enamel oxygen values in clinic-extracted human dental enamel with known provenance. The results from this study indicate that the theoretical isotopic relationship between enamel and drinking water oxygen is weak at the city and country-level. Differences of up to 15‰ were observed between predicted drinking water oxygen values using existing models and observed values, highlighting the complexity of using water/enamel conversion equations. The lower isotopic boundary of enamel oxygen values is now understood for Metro Vancouver at δ18Oc(VPDB) = – 11.0‰ and presents the possibility of using stable isotope analysis as an exclusionary tool where individuals falling below threshold value can be identified as non-local. Overall, this study’s results support the development of geographical reference maps for human enamel oxygen.


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