Stabilization of the amplification convertase of complement by monoclonal antibodies directed against human factor B

Three IgM mouse monoclonal antibodies (MoAb), 5B5-A, 2D2-B, and 5B12-A, were prepared by fusion of spleen cells from mice immunized with human B with the SP 2/0 myeloma cell line. They were assessed for their effect on cell-bound and fluid-phase amplification convertases of complement (C) with purified proteins in vitro. 5B5-A and 2D2-B were similar in their effects on cell-bound preformed C3bBb in that they bound to cell-bound C3bBb, stabilized the C3bBb convertase, and rendered the C3bBb convertase relatively resistant to the plasma protein H. These two MoAb were also able to enhance C3 consumption in vitro in reaction mixtures containing C3b, C3, B, and D. At the same time, they presumably stabilized the C3 convertase and caused relative sparing of B hemolytic activity in the reaction mixtures. In contrast, 5B12-A, which also bound to Bb and C3bBb, did not induce any stabilization, but rather caused accelerated decay of cell-bound C3bBb. These results indicate that MoAb against B can have C3NeF-like activity. On the other hand, not all MoAb against B have stabilizing activity on the C3bBb convertase.     

C3 nephritic factor (C3NeF): stabilization of fluid phase and cell-bound alternative pathway convertase.

C3 nephritic factor (C3NeF) defined by the capacity of nephritic serum and its fractions to initiate loss of the B antigen of C3 in normal serum was purified from the serum of three different donors and shown to function by stabilization of membrane-bound and fluid phase alternative pathway C3 convertase. C3NeF converts cell-bound C3B sites in a dose-related manner to CEB(NeF) sites, which exhibit an approximate 10-fold increase in half-life. The linear relationship between the C3NeF input and the residual hemolytic sites on EAC43B present after incubation for 20 min at 30 degrees C, during which labile C3B sites have decayed, indicates that the number of residual C3B sites is directly related to the dose of C3NeF. The capacity of C3NeF to stabilize the C3B convertase in a temperature- and dose-dependent manner, which is independent of binding or consumption of C3NeF, in a fluid phase reaction mixture of 125I-B, 131I-C3 and D permits isolation of a 10S complex containing radiolabeled C3 and B and exhibiting C3, convertase activity on an exogenous C3 source. Thus, the stabilizing effect of C3NeF is not limited to membrane-bound C3B but is also sufficient to permit recovery of a fluid phase C3 convertase formed during the interaction of C3, B, and D.     

Exercise training in childhood-onset systemic lupus erythematosus: a controlled randomized trial

Introduction

Exercise training has emerged as a promising therapeutic strategy to counteract physical dysfunction in adult systemic lupus erythematosus. However, no longitudinal studies have evaluated the effects of an exercise training program in childhood-onset systemic lupus erythematosus (C-SLE) patients. The objective was to evaluate the safety and the efficacy of a supervised aerobic training program in improving the cardiorespiratory capacity in C-SLE patients.

Methods

Nineteen physically inactive C-SLE patients were randomly assigned into two groups: trained (TR, n = 10, supervised moderate-intensity aerobic exercise program) and non-trained (NT, n = 9). Gender-, body mass index (BMI)- and age-matched healthy children were recruited as controls (C, n = 10) for baseline (PRE) measurements only. C-SLE patients were assessed at PRE and after 12 weeks of training (POST). Main measurements included exercise tolerance and cardiorespiratory measurements in response to a maximal exercise (that is, peak VO₂, chronotropic reserve (CR), and the heart rate recovery (ΔHRR) (that is, the difference between HR at peak exercise and at both the first (ΔHRR1) and second (ΔHRR2) minutes of recovery after exercise).

Results

The C-SLE NT patients did not present changes in any of the cardiorespiratory parameters at POST (P > 0.05). In contrast, the exercise training program was effective in promoting significant increases in time-to-exhaustion (P = 0.01; ES = 1.07), peak speed (P = 0.01; ES = 1.08), peak VO₂ (P = 0.04; ES = 0.86), CR (P = 0.06; ES = 0.83), and in ΔHRR1 and ΔHRR2 (P = 0.003; ES = 1.29 and P = 0.0008; ES = 1.36, respectively) in the C-SLE TR when compared with the NT group. Moreover, cardiorespiratory parameters were comparable between C-SLE TR patients and C subjects after the exercise training intervention, as evidenced by the ANOVA analysis (P > 0.05, TR vs. C). SLEDAI-2K scores remained stable throughout the study.

Conclusion

A 3-month aerobic exercise training was safe and capable of ameliorating the cardiorespiratory capacity and the autonomic function in C-SLE patients.

Trial registration

NCT01515163.     

Automated Entire Thrombus Density Measurements for Robust and Comprehensive Thrombus Characterization in Patients with Acute Ischemic Stroke

Background and Purpose

In acute ischemic stroke (AIS) management, CT-based thrombus density has been associated with treatment success. However, currently used thrombus measurements are prone to inter-observer variability and oversimplify the heterogeneous thrombus composition. Our aim was first to introduce an automated method to assess the entire thrombus density and then to compare the measured entire thrombus density with respect to current standard manual measurements.

Materials and Method

In 135 AIS patients, the density distribution of the entire thrombus was determined. Density distributions were described using medians, interquartile ranges (IQR), kurtosis, and skewedness. Differences between the median of entire thrombus measurements and commonly applied manual measurements using 3 regions of interest were determined using linear regression.

Results

Density distributions varied considerably with medians ranging from 20.0 to 62.8 HU and IQRs ranging from 9.3 to 55.8 HU. The average median of the thrombus density distributions (43.5 ± 10.2 HU) was lower than the manual assessment (49.6 ± 8.0 HU) (p<0.05). The difference between manual measurements and median density of entire thrombus decreased with increasing density (r = 0.64; p<0.05), revealing relatively higher manual measurements for low density thrombi such that manual density measurement tend overestimates the real thrombus density.

Conclusions

Automatic measurements of the full thrombus expose a wide variety of thrombi density distribution, which is not grasped with currently used manual measurement. Furthermore, discrimination of low and high density thrombi is improved with the automated method.     

Towards a framework for the evolutionary genomics of Kinetoplastids: what kind of data and how much?

The current status of kinetoplastids phylogeny and evolution is discussed in view of the recent progresses on genomics. Some ideas on a potential framework for the evolutionary genomics of kinetoplastids are presented.     

The role of intravascular ultrasound imaging in vascular brachytherapy

Intracoronary brachytherapy has recently emerged as a new therapy to prevent restenosis. Initial experimental work was achieved in animal models and the results were assessed by histomorphometry. Initial clinical trials used angiography to guide dosimetry and to assess efficacy. Intravascular ultrasound (IVUS) permits tomographic examination of the vessel wall, elucidating the true morphology of the lumen and transmural components, which cannot be investigated on the lumenogram obtained by angiography. This paper reviews the use of IVUS in the clinical studies of brachytherapy conducted to date. IVUS allows clinicians to make a thorough assessment of the remodeling of the vessel and appears to have a major role to play in facilitating understanding of the underlying mechanisms of action in this emerging field. The authors propose that state-of-the-art IVUS techniques should be employed to further knowledge of the mechanisms of action of brachytherapy in atherosclerotic human coronary arteries.     

Complement dependent amplification of the innate response to a cognate microbial ligand by the long pentraxin PTX3

The long pentraxin PTX3 is a fluid-phase pattern recognition receptor, which plays a nonredundant role in resistance against selected pathogens. PTX3 has properties similar to Abs; its production is induced by pathogen recognition, it recognizes microbial moieties, activates complement, and facilitates cellular recognition by phagocytes. The mechanisms responsible for the effector function of PTX3 in vivo have not been elucidated. OmpA, a major outer membrane protein of Gram-negative Enterobacteriaceae, is a microbial moiety recognized by PTX3. In the air pouch model, KpOmpA induces an inflammatory response, which is amplified by coadministration of PTX3 in terms of leukocyte recruitment and proinflammatory cytokine production. PTX3 did not affect the inflammatory response to LPS, a microbial moiety not recognized by PTX3. As PTX3 binds to C1q and modulates the activation of the complement cascade, we assessed the involvement of complement in the amplification of the response elicited by KpOmpA and PTX3. Experiments performed using cobra venom factor, C1-esterase inhibitor, and soluble complement receptor 1 indicate that PTX3 amplifies the inflammatory response to KpOmpA through complement activation. The results reported here demonstrate that PTX3 activates a complement-dependent humoral amplification loop of the innate response to a microbial ligand.     

Improving model construction of profile HMMs for remote homology detection through structural alignment

Background  

Remote homology detection is a challenging problem in Bioinformatics. Arguably, profile Hidden Markov Models (pHMMs) are one of the most successful approaches in addressing this important problem. pHMM packages present a relatively small computational cost, and perform particularly well at recognizing remote homologies. This raises the question of whether structural alignments could impact the performance of pHMMs trained from proteins in the Twilight Zone, as structural alignments are often more accurate than sequence alignments at identifying motifs and functional residues. Next, we assess the impact of using structural alignments in pHMM performance.