Role of nonconserved charged residues of the AE2 transmembrane domain in regulation of anion exchange by pH

The ubiquitous AE2/SLC4A2 anion exchanger is acutely and independently regulated by intracellular (pH_i) and extracellular pH (pH_o), whereas the closely related AE1/SLC4A1 of the red cell and renal intercalated cell is relatively pH-insensitive. We have investigated the contribution of nonconserved charged residues within the C-terminal transmembrane domain (TMD) of AE2 to regulation by pH through mutation to the corresponding AE1 residues. AE2-mediated Cl⁻/Cl⁻ exchange was measured as 4,4′-di-isothiocyanatostilbene-2,2′-disulfonic acid-sensitive ³⁶Cl⁻ efflux from Xenopus oocytes by varying pH_i at constant pH_o, and by varying pH_o at near-constant pH_i. All mutations of nonconserved charged residues of the AE2 TMD yielded functional protein, but mutations of some conserved charged residues (R789E, R1056A, R1134C) reduced or abolished function. Individual mutation of AE2 TMD residues R921, F922, P1077, and R1107 exhibited reduced pH_i sensitivity compared to wt AE2, whereas TMD mutants K1153R, R1155K, R1202L displayed enhanced sensitivity to acidic pH_i. In addition, pH_o sensitivity was significantly acid- shifted when nonconserved AE2 TMD residues E981, K982, and D1075 were individually converted to the corresponding AE1 residues. These results demonstrate that multiple conserved charged residues are important for basal transport function of AE2 and that certain nonconserved charged residues of the AE2 TMD are essential for wild-type regulation of anion exchange by pH_i and pH_o. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. A. K. Stewart and C. E. Kurschat have contributed equally to this work.     

Mandibular involvement of solitary plasmocytoma: a case report

Plasma cell neoplasms (multiple myeloma, solitary plasmocytoma of bone and extra medullar plasmocytoma) are characterized by a monoclonal neoplastic proliferation of plasma cells. Solitary plasmocytoma of bone (SPB) is a localized form of them. SPB is most frequently seen in vertebrae and secondarily in long bones. Its presence in jaws is extremely rare and when it is seen, angulus and ramus mandible are most common sites of occurrence. Prognosis of SPB is worse than extra medullar plasmacytoma (EMP) and approximately 50% of SPB will transform to multiple myelom. A 76-year old woman consulted to our clinic with a chief complaint of slowly developed swelling in her mandible. She had an operation from caput femur because of plasmocytoma two months before. Panoramic radiography revealed a radiolucent lesion in the mandibular anterior region, 60x35 mm in dimension. Aspiration biopsy was performed and histopathological examination was reported as plasmocytoma. She was referred to the oncology department for treatment but died before the treatment finished.     

The prosthodontic restoration of a self-inflicted gunshot maxillofacial defect: a short-term follow-up case report

A self-inflicted gunshot maxillofacial defect was restored with dental implants and various attachments. Following mandibular surgical reconstruction, a fixed full-arch implant-supported prosthesis was fabricated. The maxillary defect was restored with an obturator retained with bar-clip and ball attachments. Crowns with an unfavorable crown-to-root ratio were used to rectify a compromised unilateral interocclusal space. Functional rehabilitation was achieved without any pathologic sequelae and maintained over a 1-year observation period. Provision of a fixed implant-retained mandibular prosthesis opposing a specific design for a maxillary obturator provided short-term and optimistic prognosis in the management of a serious traumatic injury.     

Incomplete mobilization of the maxilla resulting in failed maxillary distraction: a case report

Maxillary distraction osteogenesis has become an accepted alternative method in the treatment of patients with severe maxillary hypoplasia in craniofacial syndromes and cleft-related deformities. Insufficient distraction, undesirable soft tissue changes, and occurrence of defective distraction vectors are among the potential complications of intraoral maxillary distraction osteogenesis. A 2-stage procedure combining maxillary advancement by distraction technique with genioplasty and mandibular setback surgery was planned to correct jaw deformities in a 22-year-old patient with severe maxillary retrusion, mandibular prognathism, and excessive lower facial height. In the first stage, osteotomies were performed and maxilla was lightly mobilized after down-fracture. Distractors were placed to the maxilla intraorally. During activation period, the maxilla rotated in a clockwise direction, producing a discrepancy between the planned and the actual vectors. Complete distraction was unsatisfactory and the complication was due to surgical technique. This case report presents the failure of maxillary distraction due to incomplete mobilization of the maxilla. Treatment of the case was achieved by the conventional osteotomy techniques at final operation. The maxilla was successfully advanced to the desired position producing good occlusion and an improved facial profile.     

Comparison of magnesium versus titanium screw fixation for biplane chevron medial malleolar osteotomy in the treatment of osteochondral lesions of the talus

European Journal of Orthopaedic Surgery & Traumatology - This retrospective study aimed to compare the clinical and radiological outcomes of patients who underwent biplane chevron medial...