ABSTRACT
Background/aim: In recent years, single-domain antibodies, also known as nanobodies, have emerged as an alternative to full immunoglobulin Gs (IgGs), due to their various advantages, including increased solubility, faster clearance, and cheaper production. Nanobodies are generally derived from the variable domain of the camelid heavy-chain-only immunoglobulin Gs (hcIgGs). Due to the high sequence homology between variable heavy chains of camelids (VHHs) and humans (VHs), hcIgGs are ideal candidates for nanobody development. However, further examination is needed to understand the structural differences between VHs and VHHs. This analysis is essential for nanobody engineering to mitigate potential immunogenicity, while preserving stability, functionality, and antigen specificity. Materials and methods: We obtained the VH and VHH sequences of various camelid and non-camelid mammalian antibodies from public databases and used multiple sequence alignment based on the Chothia numbering scheme. Aligned sequences were subjected to diverse analyses encompassing paratope length, binding prediction, motif, disulfide bridge, salt bridge profiling, and physicochemical characteristic distribution. Logistic Regression coupled with the Boruta - Random Forest algorithm facilitated the comprehensive examination of physicochemical properties. Results: Our findings revealed longer, less variable paratope sequences in VHHs, along with specific antigen binding residues with increased binding potential compared to VHs. Although the VHs showed more heterogeneous noncanonical disulfide bond patterns, the VHHs had a higher number of noncanonical disulfide bridges. Intriguingly, a typical salt bridge between the 94th and 101st positions in the VHs had a very low encounter rate in the VHHs. Surprisingly, we also identified notable differences in the physicochemical patterns of mostly conserved frameworks (FWs), especially the FW2 and FW3 regions, between VHs and VHHs. Conclusion: Our findings point to possible key sites in VHHs as candidate residues for nanobody engineering efforts.
ABSTRACT
OBJECTIVE: One-quarter of deaths in children with chronic renal failure is due to cardiovascular complications. Conventional echocardiographic methods are insufficient for evaluating systolic functions in children with chronic renal failure. The aim of the present study was to investigate cardiac functions in children with chronic renal failure by evaluating left atrial volume and functions. METHODS: The present cross-sectional observational study included 44 children undergoing dialysis, 16 children with chronic renal failure but not yet on dialysis, and 20 healthy control subjects. Transthoracic echocardiography was performed for all children. Variables regarding to left ventricle and atrium (left atrial systolic force, left atrial systolic force index, left atrial volume, left ventricular mass index, and relative wall thickness) were measured using two-dimensional and M-mode echocardiography. RESULTS: Left atrial systolic force index was negatively correlated with systolic blood pressure and left ventricular mass (p=0.01, r=0.266 and p=0.02, r=0.347, respectively). However, it was positively correlated with both early and late diastolic mitral inflow velocity (r=0.518, p=0.001 and r=0.828, p=0.001, respectively). There were no significant difference among the groups in terms of left atrial systolic force index and left atrial volume. However, left atrial systolic force index was higher in children with chronic renal failure but not yet on dialysis. CONCLUSION: Left atrial systolic force was negatively correlated with systolic blood pressure and left ventricular mass. These findings suggested that evaluating left atrial systolic force and left atrial volume were useful to determine diastolic dysfunction and the necessity of dialysis in patient with chronic renal failure.
