Characterization of mouse switch variant antibodies by matrix-assisted laser desorption ionization mass spectrometry and electrospray ionization mass spectrometry

The amino acid sequences of mouse monoclonal antibodies have been characterized completely by mass spectrometry. Antibodies used in the present study were derived from mouse switch variant cell lines that produce four kinds of immunoglobulin Gs (IgGs). The amino acid sequences of these antibodies had not been estimated from the corresponding DNA sequence, so the sequences of IgGs derived from other strains were used as references in this study. Intra- and interchain disulfide bonds of the IgGs were reduced and carboxymethylated and the products were subjected to proteolytic digestion. The existence of N-linked oligosaccharides also was taken into account. The capabilities and limitations of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and capillary liquid chromatography-electrospray ionization mass spectrometry are discussed in the structural characterization of the antibodies. Based on our results, allotypes of the antibodies examined are discussed. This study shows that amino acid sequences of proteins, such as IgG, can be investigated without information about the corresponding DNA sequence if appropriate reference sequences derived from other strains can be used

An Elderly Woman With Gibbus Deformity and Physiologic Shock

Physiological shock requires prompt diagnosis and treatment in the emergency department. We present a case of physiological shock in a 91-year-old woman resulting from obstruction of the left atrium and inferior vena cava by a giant esophageal hiatal hernia, identified using computed tomography imaging. The patient’s age and history, including diet and eating behavior (namely needing to lie down immediately after a meal), and kyphotic posture were important factors to consider in establishing the differential diagnosis. While rare, a giant esophageal hiatal hernia should be considered in the differential diagnosis of obstructive shock

An Elderly Woman With Gibbus Deformity and Physiologic Shock

Physiological shock requires prompt diagnosis and treatment in the emergency department. We present a case of physiological shock in a 91-year-old woman resulting from obstruction of the left atrium and inferior vena cava by a giant esophageal hiatal hernia, identified using computed tomography imaging. The patient’s age and history, including diet and eating behavior (namely needing to lie down immediately after a meal), and kyphotic posture were important factors to consider in establishing the differential diagnosis. While rare, a giant esophageal hiatal hernia should be considered in the differential diagnosis of obstructive shock

How do case presentation teaching methods affect learning outcomes?-SNAPPS and the One-Minute preceptor

Background: Various techniques have been developed to enable preceptors to teach residents effectively in outpatient settings to promote active learning, including SNAPPS and the One-Minute Preceptor (OMP). This study aimed to ascertain the differences between SNAPPS and the OMP in case presentation content and learner evaluation when used to teach residents about case presentation. Methods: From 2011 to 2013, participants were 71 junior clinical residents employed in two hospitals for clinical training. They were randomly allocated to two groups, one using SNAPPS and the other the OMP. From recorded discussions, the "differential diagnoses", "questions and uncertainties", "treatment plans", and "learning issues" were counted. Also, a self-evaluation form was distributed at the end of the study to evaluate the residents' satisfaction with the case presentation. Results: Members of the SNAPPS group used significantly more meaning units related to questions and uncertainties compared with those of the OMP group (P < 0.001). Self-evaluation sheets revealed that members of the SNAPPS group had significantly higher positive responses than those of the OMP group in terms of the following evaluations: "It was easy to bring up questions and uncertainties" (P = 0.046), "It was easy to present the case efficiently" (P = 0.002), "It was easy to present the case in the sequence given" (P = 0.029), and "I was able to give an in-depth case presentation" (P = 0.005). Conclusions: SNAPPS may induce more meaning units related to questions and uncertainties and give more satisfaction to residents than the OMP

An electrospray-ionization mass spectrometry analysis of the pH-dependent dissociation and denaturation processes of a heterodimeric protein

AbstractElectrospray ionization mass spectrometry (ESI-MS) was applied to the analysis of the dissociation and denaturation processes of a heterodimeric yeast killer toxin SMKT. The two distinct subunits of SMKT noncovalently associate under acidic conditions, but become dissociated and denatured under neutral and basic conditions. In order to understand the unique pH-dependent denaturation mechanism of this protein, a pH titration was performed by utilizing ESI-MS. The molecular ions of the heterodimer which possesses the highly ordered structure, were mainly observed below pH 4.6. However, the two subunits immediately dissociated at this pH. The spectra measured with various settings of the mass spectrometer indirectly demonstrated that the pH-dependent dissociation occurs in the liquid phase. The current result as well as the three-dimensional structure of SMKT suggest that the deprotonation of a specific carboxyl group triggers a cooperative dissociation process of this protein. In conclusion, the pH titration of a protein by ESI-MS is particularly effective, when the unfolding process or the biological function of the protein is related to the interaction with other molecules