A generic approach to engineer antibody pH-switches using combinatorial histidine scanning libraries and yeast display

There is growing interest in the fast and robust engineering of protein pH-sensitivity that aims to reduce binding at acidic pH, compared to neutral pH. Here, we describe a novel strategy for the incorporation of pH-sensitive antigen binding functions into antibody variable domains using combinatorial histidine scanning libraries and yeast surface display. The strategy allows simultaneous screening for both, high affinity binding at pH 7.4 and pH-sensitivity, and excludes conventional negative selection steps. As proof of concept, we applied this strategy to incorporate pH-dependent antigen binding into the complementary-determining regions of adalimumab. After 3 consecutive rounds of separate heavy and light chain library screening, pH-sensitive variants could be isolated. Heavy and light chain mutations were combined, resulting in 3 full-length antibody variants that revealed sharp, reversible pH-dependent binding profiles. Dissociation rate constants at pH 6.0 increased 230- to 780-fold, while high affinity binding at pH 7.4 in the sub-nanomolar range was retained. Furthermore, binding to huFcRn and thermal stability were not affected by histidine substitutions. Overall, this study emphasizes a generalizable strategy for engineering pH-switch functions potentially applicable to a variety of antibodies and further proteins-based therapeutics.

Self-Assembled Hybrid Aptamer-Fc Conjugates for Targeted Delivery: A Modular Chemoenzymatic Approach

Over the past decade, DNA and RNA aptamers have attracted keen research interest due to their ability to specifically bind targets of therapeutic relevance. However, their application is often hampered by a short serum half-life and missing effector functions. Conjugation of aptamers to antibody Fc fragments could improve pharmacokinetics, enable immune effector mechanisms, and provide an option for the introduction of desired payloads (e.g., toxins or fluorescent dyes). We developed a modular scaffold-supported system based on human IgG1 Fc fragments, which allows for its dual functionalization with moieties of interest. In our approach, two bioorthogonal, enzyme-mediated reactions were used in combination with oxime ligation and self-assembly based on PNA-DNA base pairing. Thus, an engineered synthetic peptide nucleic acid (PNA) oligomer was coupled to the C-termini of the Fc dimer upon sequence-specific sortase A-mediated transpeptidation. Hybridization of the resulting Fc-PNA conjugate with a tailored DNA aptamer that binds cancer-related hepatocyte growth factor receptor (c-MET) led to a hybrid construct which showed strong and specific binding to c-MET and was readily internalized by c-MET-overexpressing cells. To install an additional orthogonally addressable site, aldehyde tag technology was applied followed by oxime ligation with an aminooxy-bearing fluorescent dye as model cargo. Delivery of fluorescent probe specifically to c-MET-overexpressing cells was confirmed by flow cytometry. Our approach can provide access to engineered aptamer-Fc conjugates with desired target specificity and cytotoxic payloads.

A vacuum-formed splint for luxated tooth with a repositioning on the model

The results of fixation of a luxated tooth using a vacuum-formed splint, formed on a plaster model after repositioning of the luxated tooth on the model are presented. This may be useful where the adjacent tooth gap is wide or only minimal anchorage and support are available from the adjacent teeth.

Tourette's syndrome with rapid deterioration by self-mutilation of the upper lip

A case of Tourette's syndrome is presented in a thirteen-year-old boy with obsessive-compulsive symptoms including self-mutilation of the upper lip. His upper lip injury was caused by complication of picking with fingernail, and self-biting with the lower anterior teeth. It became rapidly worse and the median part of the upper lip collapsed. But the placement of an acrylic splint was able to prevent further damage of the upper lip.

Oropharyngeal airway appliance for infant with upper airway obstruction: report of a case

A palatal appliance with oropharyngeal tube that reduces the upper airway obstructions of an eleven-month-old male infant with severe cerebral palsy is presented. The palatal appliance was composed of the base plate, the outer guide tube that held the oropharyngeal tube inside it, and the extra outer guide tube for the suction catheter. After the setting of the appliance, respiratory distress was improved without side effects.

Primary intraosseous carcinoma associated with impacted third molar of the mandible: review of the literature and report of a new case

This study investigated the clincopathologic features of primary intraosseous carcinoma (PIOC) related to the third molar of the mandible. Six cases (5 from the literature and 1 new case; mean patient age 73 years) of PIOC associated with completely impacted lower third molar were analyzed. For comparison, 8 cases of PIOC presenting after extraction of the lower third molar were also evaluated, with a significantly lower mean patient age of 56 years. Most lesions were deceptively similar to those related to the lateral type of dentigerous cyst, and half of the impacted cases revealed an asymptomatic fracture of the mandible. In all patients except for the present case, metastasis had not been recorded. Surprisingly, no patients are known to have died of PIOC. In our experience the prognosis of PIOC associated with a completely impacted third molar is much better than commonly believed, although the number of cases involved is too small to make a general conclusion. However, delay in establishing the correct diagnosis followed by extraction without awareness of the carcinoma is know to adversely affect the prognosis.

Soft tissue myxoma of the gingiva: report of a case and review of the literature of soft tissue myxoma in the oral region

Soft tissue myxoma of the oral cavity is extremely rare. We present a case of soft tissue myxoma arising from a mandibular anterior gingiva in a 51-year-old male patient. Histological examination showed islands of odontogenic epithelium scattered in the mucinous stroma. This lesion was supposed to have a odontogenic origin. The clinical differences between soft tissue myxoma with bone destruction and those without bone destruction are also discussed by a review of the literature.

A case of an electrical burn in the oral cavity of an adult

Electrical burns in the oral cavity account for 2.2% of all electrical burns and only 0.12% of all burns; thus, the incidence of electrical burns in the oral cavity is relatively low. As this type of injury occurs in the oral cavity when an individual sucks or chews on a live electrical wire, extension cord, plug, or outlet, most cases occur in toddlers or preschool children, and adult cases are extremely rare. Here we describe a case of an electrical burn in a 56-year-old man who accidentally bit the electric wire of a cleaner while carrying out repairs. Conservative treatment, without surgery, was performed. Two years after the injury, a slight scar and a small tongue deformity remain, but no functional disturbance has been observed.

So-called simple bone cyst of the jaw: a family of pseudocysts of diverse nature and etiology

The nature and etiology of so-called simple bone cyst (SBC) are still a subject of debate. Our comprehensive review of the literature suggests that SBC, which appears histologically to be a single entity, has different natures and etiologies, resulting in divergent clinical features. In addition, an interesting case of mandibular SBC in an 11-year-old girl is presented with details of radiographic changes over a 7-year period. Fully documented patient records revealed that this lesion originated in the apical area of the first molar and took about 4 years to develop into a clinically evident bony expansion.