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The Journal of Biological Chemistry Jan 1999Enteropeptidase is a heterodimeric type II membrane protein of the brush border of duodenal enterocytes. In this location, enteropeptidase cleaves and activates...
Enteropeptidase is a heterodimeric type II membrane protein of the brush border of duodenal enterocytes. In this location, enteropeptidase cleaves and activates trypsinogen, thereby initiating the activation of other intestinal digestive enzymes. Recombinant bovine enteropeptidase was sorted directly to the apical surface of polarized Madin-Darby canine kidney cells. Replacement of the cytoplasmic and signal anchor domains with a cleavable signal peptide (mutant proenteropeptidase lacking the amino-terminal signal anchor domain (dSA-BEK)) caused apical secretion. The additional amino-terminal deletion of a mucin-like domain (HL-BEK) resulted in secretion both apically and basolaterally. Further deletion of the noncatalytic heavy chain (L-BEK) resulted in apical secretion. Thus enteropeptidase appears to have at least three distinct sorting signals as follows: the light chain (L-BEK) directs apical sorting, addition of most of the heavy chain (HL-BEK) inhibits apical sorting, and addition of the mucin-like domain (dSA-BEK) restores apical sorting. Inhibition of N-linked glycosylation with tunicamycin or disruption of microtubules with colchicine caused L-BEK to be secreted equally into apical and basolateral compartments, whereas brefeldin A caused basolateral secretion of L-BEK. Full-length BEK was not found in detergent-resistant raft domains of Madin-Darby canine kidney cells or baby hamster kidney cells. These results suggest apical sorting of enteropeptidase depends on N-linked glycosylation of the serine protease domain and an amino-terminal segment that includes an O-glycosylated mucin-like domain and three potential N-glycosylation sites. In contrast to many apically targeted proteins, enteropeptidase does not form detergent-resistant associations with sphingolipid-cholesterol rafts.
Topics: Animals; Brefeldin A; Catalytic Domain; Cattle; Cell Line; Cell Polarity; Cholesterol; Colchicine; Cricetinae; Detergents; Dogs; Enteropeptidase; Glycosylation; Kidney; Molecular Weight; Mucins; Protein Synthesis Inhibitors; Sequence Homology, Amino Acid; Sphingolipids; Structure-Activity Relationship; Tunicamycin
PubMed: 9880538
DOI: 10.1074/jbc.274.3.1596 -
Journal of Cell Science Jul 1996A number of epithelia form tubulocysts in vitro when overlaid with type I collagen gel. Because collagen receptors are generally believed to be expressed on the...
A number of epithelia form tubulocysts in vitro when overlaid with type I collagen gel. Because collagen receptors are generally believed to be expressed on the basolateral domain, the mechanism by which collagen elicits this morphogenetic response from the apical surface is unclear. To investigate the role of beta 1 integrins, the major receptor family for collagen, in this process, we overlaid polarized monolayers of MDCK II cells grown on permeable supports with type I collagen gel and correlated integrin polarity with the polarity of other apical and basolateral membrane markers during tubulocyst formation. Polarized monolayers of one clone of MDCK II cells, referred to as Heidelberg MDCK, initially respond to collagen overlay by stratifying; within 48 hours, lumena develop between the cell layers giving rise to tubulocysts. Tight junctions remain intact during tubulocyst formation because transepithelial electrical resistance does not significantly change. Major alterations are observed, however, in the expression and localization of apical and basolateral membrane markers. beta 1 integrins are necessary for tubulocyst morphogenesis because a function-blocking antibody administered to the apical pole of the cells completely inhibits the formation of these structures. To determine how apical-cell collagen interactions elicit tubulocyst formation, we examined whether beta 1 integrins are mobilized to apical plasma membranes in response to collagen overlay. We found that in the absence of collagen, polarized monolayers of Heidelberg MDCK cells endogenously express on apical plasma membranes a small pool of the beta 1 family, including alpha 2 beta 1 and alpha 3 beta 1. Collagen overlay does not mobilize additional beta 1 integrins to apical domains. If beta 1 integrins are not already apically expressed, as in the C6 MDCK cell line (Schoenenberger et al. (1994) J. Cell Biol. 107, 527-541), beta 1 integrins are not directed apically and tubulocysts do not develop in response to collagen. Thus, interaction of beta 1 integrin pre-existing on apical plasma membranes of polarized epithelia with type I collagen gel is the mechanism by which apical application of collagen elicits the formation of tubulocysts. Depolarized integrins on apical plasma membranes of polarized epithelia may be relevant to the pathogenesis of disease and injury.
Topics: Animals; Cell Line; Cell Movement; Cell Polarity; Collagen; Culture Media; Dogs; Epithelial Cells; Epithelium; Integrin beta1
PubMed: 8832410
DOI: 10.1242/jcs.109.7.1875 -
Journal of Conservative Dentistry : JCD 2016This study evaluated whether using supplementary files for removing root canal filling residues after ProTaper Universal Retreatment files (RFs) increased the debris...
AIM
This study evaluated whether using supplementary files for removing root canal filling residues after ProTaper Universal Retreatment files (RFs) increased the debris extrusion apically.
MATERIALS AND METHODS
Eighty mandibular premolars with single root and canal were instrumented with ProTaper Universal rotary system (SX-F3) and obturated. The samples were divided randomly into four groups (n = 20). Group 1 served as a control; only ProTaper Universal RFs D1-D3 were used, and the extruded debris was weighed. Groups 2, 3, and 4 were the experimental groups, receiving a twofold retreatment protocol: Removal of the bulk, followed by the use of supplementary files. The bulk was removed by RFs, followed by the use of ProTaper NEXT (PTN), WaveOne (WO), and Self-Adjusting File (SAF) for removal of the remaining root filling residues. Debris extruded apically were weighed and compared to the control group. Statistical analysis was performed using one-way analysis of variance (ANOVA) and post hoc Tukey's test.
RESULTS
All the three experimental groups presented significant difference (P < .01). The post hoc Tukey's test confirmed that Group 4 (SAF) exhibited significantly less (P < .01) debris extrusion between the three groups tested.
CONCLUSION
SAF results in less extrusion of debris when used as supplementary file to remove root-filling residues, compared to WO and PTN.
PubMed: 27099416
DOI: 10.4103/0972-0707.178686 -
Journal of Endodontics Sep 2020This study evaluated the microbiological conditions of the apical root canal system of teeth with posttreatment apical periodontitis and correlated them with...
INTRODUCTION
This study evaluated the microbiological conditions of the apical root canal system of teeth with posttreatment apical periodontitis and correlated them with observations from cone-beam computed tomographic (CBCT) imaging, micro-computed tomographic (micro-CT) imaging, and histopathology.
METHODS
Root apices were obtained from 36 root canal-treated teeth subjected to periradicular surgery. CBCT examination was available before surgery. The apical root specimens were scanned in a micro-CT device and then cryopulverized. The powder was subjected to DNA extraction for real-time polymerase chain reaction quantification of total bacteria, Streptococcus species, members of the phylum Actinobacteria, and Enterococcus faecalis. Microbiological findings were evaluated for associations with CBCT, micro-CT, and histopathologic data. An association between lesion size and the proportion of unfilled apical canal system volume was also assessed.
RESULTS
All cryopulverized specimens were positive for total bacteria. Actinobacteria and streptococci occurred in 35 and 33 specimens, respectively, and were usually dominant in the community. Actinobacteria counts were 2.23 times higher in granulomas than in cysts. Streptococci were significantly more present in small lesion cases. E. faecalis was detected in only 7 samples, always as a dominant community member. The association of total bacteria, streptococci, and Actinobacteria counts with the unfilled canal volume was significant in the univariate analyses but not confirmed in the adjusted analyses. Large lesions were significantly associated with a higher volume of unfilled apical canals.
CONCLUSIONS
Bacterial infection occurred in all root apices, with high prevalence and dominance of Actinobacteria and streptococci. The volume of the unfilled apical canal system was significantly associated with the lesion size and possibly with bacterial counts. Findings illustrate the need to thoroughly disinfect and fill the apical root canal of infected teeth during endodontic therapy.
Topics: Dental Pulp Cavity; Enterococcus faecalis; Humans; Periapical Periodontitis; Root Canal Therapy; Tooth Apex
PubMed: 32525058
DOI: 10.1016/j.joen.2020.05.020 -
Apical expression of functional asialoglycoprotein receptor in the human intestinal cell line HT-29.Gastroenterology Nov 1997The asialoglycoprotein receptor localizes to the basolateral membrane of hepatocytes and to the apical membrane of enterocytes. The aim of this study was to examine...
BACKGROUND & AIMS
The asialoglycoprotein receptor localizes to the basolateral membrane of hepatocytes and to the apical membrane of enterocytes. The aim of this study was to examine HT-29 cells as a polarized cell model for studying apically localized endogenous asialoglycoprotein receptor.
METHODS
Subunits H1 and H2 (human) were detected by Western blot and immunoprecipitated using subunit-specific antisera against hepatic receptor peptides. Receptor function was assessed by uptake of iodinated asialo-orosomucoid, immunoglobulin (Ig) A1, and haptocorrin. Immunocytochemistry was analyzed by standard light and confocal microscopy.
RESULTS
Receptor content of the minor subunit, H2, was predominant. HT-29 cells mediated specific uptake and degradation of 125I-asialo-orosomucoid. A high-affinity (0.6 x 10(-9) mmol/L) and a low-affinity binding site were present. The specific ligand binding capacity of the apical surface was approximately twice that of the basolateral surface. Immunocytochemistry revealed a predominant apical membrane location of the minor receptor subunit, with some intracellular receptor. The apical H2 subunit was preferentially labeled with amino acid precursors compared with basolaterally located subunit. Human IgA1 bound specifically to HT-29 cells with a molar ratio of 0.26 compared with asialo-orosomucoid; porcine haptocorrin bound with a molar ratio of 1.35.
CONCLUSIONS
HT-29 cells produce a functional apically located asialoglycoprotein receptor and provide a model for receptor trafficking in the enterocyte.
Topics: Asialoglycoprotein Receptor; Asialoglycoproteins; HT29 Cells; Humans; Immunohistochemistry; Iodine Radioisotopes; Orosomucoid; Precipitin Tests; Receptors, Cell Surface; Vitamin B 12
PubMed: 9352852
DOI: 10.1053/gast.1997.v113.pm9352852 -
Journal of Endodontics Jan 1994This study evaluated the apical leakage associated with various depths of retrograde fillings placed in root apices which had been resected at one of three different... (Comparative Study)
Comparative Study
This study evaluated the apical leakage associated with various depths of retrograde fillings placed in root apices which had been resected at one of three different angles. Leakage was assessed with a hydraulic conductance apparatus. Teeth were divided into groups corresponding to the angle of apical resection (0, 30, and 45 degrees to the long axis of the root) and apical leakage was determined following incremental increases in the depth of the retrograde filling (Ketac Silver). Increasing the depth of the retrograde filling significantly decreased apical leakage; there was also a significant increase in leakage as the amount of bevel increased. Both the permeability of resected apical dentin and microleakage around the retrograde filling material had a significant influence on apical leakage.
Topics: Apicoectomy; Cermet Cements; Dental Leakage; Dentin Permeability; Humans; Retrograde Obturation
PubMed: 8182382
DOI: 10.1016/s0099-2399(06)80022-1 -
International Endodontic Journal Jun 2007To examine the clinical and radiographic appearance of teeth that suffered premature interruption of root development and were treated by an mineral trioxide aggregate...
AIM
To examine the clinical and radiographic appearance of teeth that suffered premature interruption of root development and were treated by an mineral trioxide aggregate (MTA) apical plug technique.
SUMMARY
Eleven teeth with immature root apices in 11 patients were treated nonsurgically by the manual application of MTA in the apical portion of the root canal under microscopic vision. Follow-up evaluations were performed at 1-2 years after treatment.
KEY LEARNING POINTS
Mineral trioxide aggregate appears to be a valid material to obtain periradicular healing in teeth with open apices and necrotic pulps. Ten out of 11 cases were associated with periradicular health at follow-up evaluation.
Topics: Adolescent; Adult; Aluminum Compounds; Calcium Compounds; Child; Dental Pulp Cavity; Dental Pulp Necrosis; Dental Restoration, Permanent; Drug Combinations; Female; Follow-Up Studies; Gutta-Percha; Humans; Male; Microscopy; Odontogenesis; Oxides; Root Canal Filling Materials; Root Canal Therapy; Silicates; Tooth Apex; Tooth, Nonvital; Wound Healing
PubMed: 17403040
DOI: 10.1111/j.1365-2591.2007.01240.x -
BioRxiv : the Preprint Server For... Dec 2023Apical expansion of calvarial osteoblast progenitors from the cranial mesenchyme (CM) above the eye is integral for calvarial growth and enclosure of the brain. The...
Apical expansion of calvarial osteoblast progenitors from the cranial mesenchyme (CM) above the eye is integral for calvarial growth and enclosure of the brain. The cellular behaviors and signals underlying the morphogenetic process of calvarial expansion are unknown. During apical expansion, we found that mouse calvarial primordia have consistent cellular proliferation, density, and survival with complex tissue scale deformations, raising the possibility that morphogenetic movements underlie expansion. Time lapse light sheet imaging of mouse embryos revealed that calvarial progenitors intercalate in 3D to converge supraorbital arch mesenchyme mediolaterally and extend it apically. In contrast, progenitors located further apically exhibited protrusive and crawling activity. CM cells express non-canonical Wnt/Planar Cell Polarity (PCP) core components and calvarial osteoblasts are bidirectionally polarized. We found non-canonical ligand, mutants have less dynamic cell rearrangements, protrusive activity, and a flattened head shape. Loss of cranial mesenchyme-restricted CM a gene required for secretion of all Wnt ligands, led to diminished apical expansion of OSX calvarial osteoblasts in the frontal bone primordia in a non-cell autonomous manner without perturbing proliferation or survival. Calvarial osteoblast polarization, progressive cell elongation and enrichment for actin cytoskeleton protein along the baso-apical axis were dependent on CM-Wnts. Thus, CM-Wnts regulate cellular behaviors during calvarial morphogenesis and provide tissue level cues for efficient apical expansion of calvarial osteoblasts. These findings also offer potential insights into the etiologies of calvarial dysplasias.
PubMed: 38106005
DOI: 10.1101/2023.12.05.570300 -
Brazilian Dental Journal 2016The aim of this study was to quantitatively evaluate the amount of apically extruded debris by single-file reciprocating instruments with different working lengths and...
The aim of this study was to quantitatively evaluate the amount of apically extruded debris by single-file reciprocating instruments with different working lengths and apical preparation sizes. Eighty human single-rooted mandibular incisors were used and conventional access cavities were prepared. Then, the specimens were divided into four groups (n=20), according to root canal instrumentation: Reciproc size 25, .08 taper and Reciproc size 40, .06 taper instruments were used at the foramen; Reciproc size 25, .08 taper and Reciproc size 40, .06 taper instruments were used 1 mm short of the foramen. Distilled water was used as an irrigant and the apically extruded debris were collected in pre-weighted glass vials and dried afterwards. The mean weight of debris was weighed with a microbalance and statistically analyzed using one-way analysis of variance and the post hoc Tukey multiple comparison test (p<0.05). The results showed that all experimental groups were associated with debris extrusion. No significant difference was found in the amount of apically extruded debris among all experimental groups (p>0.05). The present study demonstrated that the working length and the apical preparation size did not have a significant effect on debris extrusion when performing single-file reciprocating instrumentation.
Topics: Humans; Root Canal Preparation; Tooth Apex
PubMed: 27007341
DOI: 10.1590/0103-6440201600337 -
Journal of International Oral Health :... May 2015Obtaining a complete seal of the root canal system is a major problem in performing root canal treatment in nonvital teeth with incomplete root development and wide open...
Obtaining a complete seal of the root canal system is a major problem in performing root canal treatment in nonvital teeth with incomplete root development and wide open apices. The aim was to study apexification using mineral trioxide aggregate (MTA), clinically and radiographically over a period of 15 months. MTA was used in four cases of teeth with incomplete root development in order to achieve an apical seal and the remaining canal was obturated with gutta-percha. Clinical and radiographic assessments of teeth were done. The clinical and radiographic results indicated that apexification procedure was predictable by using MTA. The total number of patients' visits and the total time duration required to obtain an apical barrier using MTA was markedly less than that of conventional techniques using calcium hydroxide.
PubMed: 26028910
DOI: No ID Found