Characterization of the thymus in Lrp4 myasthenia gravis: Four cases

Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction. Most patients have pathogenic autoantibodies against the acetylcholine receptor (AChR). In the last years a novel subpopulation of MG patients has been described that harbors antibodies against low-density lipoprotein receptor-related protein 4 (Lrp4), another postsynaptic neuromuscular antigen. In early-onset AChR MG (EOMG), the thymus plays an important role in immunopathogenesis, and early thymectomy is beneficial. It is still unknown if the thymus plays any role in Lrp4-MG. In this pilot study, we compared thymus samples from four patients with Lrp4-MG (one pre-treated with immunosuppressive drugs), four non-MG controls and five EOMG patients (not pretreated with immunosuppressive drugs). Immunohistochemistry of the Lrp4-MG thymi revealed normal architecture, with normal numbers and distribution of B-cells, lymphoid follicles and Hassall's corpuscles. Primary CD23⁺ lymphoid follicles were similarly infrequent in Lrp4-MG and control thymic sections. In none of the control or Lrp4-MG thymi did we find secondary follicles with CD10⁺ germinal centers. These were evident in 2 of the 5 EOMG thymi, where primary lymphoid follicles were also more frequent on average, thus showing considerable heterogeneity between patients. Even if characteristic pathological thymic changes were not observed in the Lrp4 subgroup, we cannot exclude a role for the thymus in Lrp4-MG pathogenesis, since one Lrp4-MG patient went into clinical remission after thymectomy alone (at one year follow-up) and one more improved after thymectomy in combination with immunosuppressive therapy.     

Overview of Protein‐Based Biopolymers for Biomedical Application

Biopolymers are playing a vital role in biomedical applications. Among them, protein‐based biopolymers are utilized for the fabrication of tissue‐engineering constructs, therapeutic molecule delivery carriers, emulsifiers, and food packaging materials. Wide ranges of proteins are extracted from animal or plant sources and are being utilized for the fabrication of scaffolds for regenerative tissue‐engineering application. Here, an overview about the protein structure, extraction procedure, solubility, and various formulation‐based proteins found in the literature are discussed. Biopolymers display several advantages such as biocompatibility and degradability by enzymes. Methods to overcome the disadvantages of these proteins such as immunogenicity, antigenicity, and solubility are reported. Various crosslinking reagents specific to protein chemistry are discussed as well.     

Who will benefit from antiresorptive treatment (bisphosphonates)?

Bisphosphonates are very effective treatments of postmenopausal osteoporosis. They suppress bone turnover, increase bone mineral density (BMD), and maintain or improve structural and material properties of bone, thereby decreasing the risk of fractures. All patients selected for treatment according to current international guidelines can benefit from bisphosphonate therapy independently of their prevalent rate of bone turnover. Long-term extensions (up to 10 years) of pivotal clinical trials with daily bisphosphonate administration showed sustained efficacy with no evidence of adverse effects on bone metabolism and skeletal fragility. Recent studies focus on the resolution of the effects of bisphosphonates on bone metabolism and fracture risk following cessation of long-term treatment. Such studies may help to formulate treatment recommendations according to the risk of the individual patient.     

Measurement of glycated hemoglobin (HbA1c) with an automated POCT instrument in comparison with HPLC and automated immunochemistry method: evaluation of the influence of hemoglobin variants.

Our study evaluates a fast and easy way to perform point-of-care testing (POCT) measurements of glycated hemoglobin HbA1c in comparison with an immunoassay on an automated biochemistry analyzer and cation exchange chromatography, the two methods routinely used in clinical laboratories for the measurement of HbA1c. A significant finding of our study is that although the POCT instrument insert claims that the method is not affected by the presence of HbS in the heterozygous state or in combination with beta-thalassemia, discrepant results were found in some cases with such hemoglobinopathies. In these cases, the two POCT and laboratory immunoassay methods showed clinically significant positive interferences with samples containing the HbS trait. We conclude that samples with the HbS trait should be interpreted with caution when tested using the POCT instrument.     

Three-dimensional analysis of the left anterior descending coronary artery: comparison with conventional coronary angiograms

OBJECTIVE: This study aimed at comparing three-dimensional (3-D) reconstruction with two-dimensional coronary angiograms with respect to anatomical parameters that might affect plaque formation and rupture. METHODS: Sixty patients with stable left anterior descending (LAD) lesions and 60 patients with an anteroseptal myocardial infarction and recanalized LAD were studied. RESULTS: Conventional angiography significantly underestimated the distance of the stenosis from the ostium of the LAD, 29.4+/-14.5 versus 35.3+/-18.5 mm, P<0.001. Vessel curvature at the site of the lesion was overestimated by conventional angiography compared with 3-D reconstruction, 147.6+/-30.6 degrees versus 162.3+/-11.2 degrees , P<0.001, as was axial bending of the LAD owing to ventricular contraction (17.8+/-7.78 degrees vs. 8.9+/-8.9 degrees , P<0.001). No agreement was observed between two-dimensional and 3-D analysis for either curvature on lesion or axial bending assessment, with intraclass correlation coefficient values 0.155 (-0.009, 0.315) and -0.022 (-0.183, 0.174), respectively. No significant agreement was found between the two methods in the detection of on-stenosis bifurcations (1.7%, kappa=0.086, P=0.349). CONCLUSION: Conventional coronary angiography cannot provide accurate estimates of anatomical parameters, such as distance of a coronary stenosis from the ostium of the vessel, coronary artery curvature at the site of stenosis, axial deformity and bending because of ventricular contraction, and classification of bifurcations. Reconstruction of the coronary tree in 3-D space is necessary for such estimations.     

Chronic acidosis with metabolic bone disease: Effect of alkali on bone morphology and vitamin D metabolism

Chronic metabolic acidosis and osteomalacia developed in two patients following urinary diversion. Good clinical, biochemical, and histologic responses were seen following treatment with alkali alone (vitamin D was not given), despite the presence of markedly impaired glomerular filtration in one of the patients. Plasma 25-hydroxy vitamin D and 1α,25-dihydroxyvitamin D concentrations were normal before and during treatment in one of the patients and in the other were low before and normal during treatment. The results show that successful treatment of the osteomalacia of chronic acidosis is not necessarily accompanied by changes in the plasma levels of vitamin D metabolites and that even when marked glomerular dysfunction coexists with acidosis and osteomalacia, treatment with alkali may be more appropriate than the administration of vitamin D analogues.     

An improved curvilinear gradient method for parameter optimization in complex biological models

Mathematical modeling is an often used approach in biological science which, given some understanding of a system, is employed as a means of predicting future behavior and quantitative hypothesis testing. However, as our understanding of processes becomes more in depth, the models we use to describe them become correspondingly more complex. There is a paucity of effective methods available for sampling the vast objective surfaces associated with complex multiparameter models while at the same time maintaining the accuracy needed for local evaluation of minima—all in a practical time period. We have developed a series of modifications to the curvilinear gradient method for parameter optimization. We demonstrate the power and efficiency of our routine through fitting of a 22 parameter Markov state model to an electrophysiological recording of a cardiac ion channel. Our method efficiently and accurately locates parameter minima which would not be easily identified using the currently available means. While the computational overhead involved in implementing the curvilinear gradient method may have contributed to resistance to adopting this technique, the performance improvements allowed by our modifications make this an extremely valuable tool in development of models of complex biological systems.     

Preferential production of IgG1, IL-4 and IL-10 in MuSK-immunized mice

Myasthenia gravis (MG) is an autoimmune disease characterized by muscle weakness associated with acetylcholine receptor (AChR), muscle-specific receptor kinase (MuSK) or low-density lipoprotein receptor-related protein 4 (LRP4)-antibodies. MuSK-antibodies are predominantly of the non-complement fixing IgG4 isotype. The MuSK associated experimental autoimmune myasthenia gravis (EAMG) model was established in mice to investigate immunoglobulin (Ig) and cytokine responses related with MuSK immunity. C57BL/6 (B6) mice immunized with 30 μg of recombinant human MuSK in incomplete or complete Freund's adjuvant (CFA) showed significant EAMG susceptibility (> 80% incidence). Although mice immunized with 10 μg of MuSK had lower EAMG incidence (14.3%), serum MuSK-antibody levels were comparable to mice immunized with 30 μg MuSK. While MuSK immunization stimulated production of all antibody isotypes, non-complement fixing IgG1 was the dominant anti-MuSK Ig isotype in both sera and neuromuscular junctions. Moreover, MuSK immunized IgG1 knockout mice showed very low serum MuSK-antibody levels. Sera and MuSK-stimulated lymph node cell supernatants of MuSK immunized mice showed significantly higher levels of IL-4 and IL-10 (but not IFN-γ and IL-12), than those of CFA immunized mice. Our results suggest that through activation of Th2-type cells, anti-MuSK immunity promotes production of IL-4, which in turn activates anti-MuSK IgG1, the mouse analog of human IgG4. These findings might provide clues for the pathogenesis of other IgG4-related diseases as well as development of disease specific treatment methods (e.g. specific IgG4 inhibitors) for MuSK-related MG.