Conditional ligands for Asian HLA variants facilitate the definition of CD8+ T‐cell responses in acute and chronic viral diseases

Conditional ligands have enabled the high‐throughput production of human leukocyte antigen (HLA) libraries that present defined peptides. Immunomonitoring platforms typically concentrate on restriction elements associated with European ancestry, and such tools are scarce for Asian HLA variants. We report 30 novel irradiation‐sensitive ligands, specifically targeting South East Asian populations, which provide 93, 63, and 79% coverage for HLA‐A, ‐B, and ‐C, respectively. Unique ligands for all 16 HLA types were constructed to provide the desired soluble HLA product in sufficient yield. Peptide exchange was accomplished for all variants as demonstrated by an ELISA‐based MHC stability assay. HLA tetramers with redirected specificity could detect antigen‐specific CD8⁺ T‐cell responses against human cytomegalovirus, hepatitis B (HBV), dengue virus (DENV), and Epstein‐Barr virus (EBV) infections. The potential of this population‐centric HLA library was demonstrated with the characterization of seven novel T‐cell epitopes from severe acute respiratory syndrome coronavirus, HBV, and DENV. Posthoc analysis revealed that the majority of responses would be more readily identified by our unbiased discovery approach than through the application of state‐of‐the‐art epitope prediction. This flow cytometry‐based technology therefore holds considerable promise for monitoring clinically relevant antigen‐specific T‐cell responses in populations of distinct ethnicity.     

Endoscopic Resection Followed by Proton Therapy With Pencil Beam Scanning for Skull Base Tumors

For patients who require postoperative radiotherapy after endoscopic resection of skull base tumors, proton therapy with pencil beam scanning (PBS) may allow sparing of normal tissue compared to intensity‐modulated photon radiation (IMRT). We compared PBS and IMRT radiation plans in the preoperative and postoperative settings for two patients with advanced skull base tumors following endoscopic resection. The benefits of PBS over IMRT appear greater in the postoperative setting following endoscopic resection with improved sparing of critical organs at risk. The multidisciplinary approach of endoscopic resection followed by PBS represents a treatment paradigm with potential for improvements in toxicity reduction. Laryngoscope, 129:1313–1317, 2019     

Immunoelectrophoretic studies on human small intestinal brush border proteins: cellular alterations in the levels of brush border enzymes after jejunoileal bypass operation.

The amounts of lactase (EC 3.2.1.23), sucrase (EC 3.2.1.48), maltase (EC 3.2.1.20), microvillus aminopeptidase (microsomal EC3.4.11.2), and dipeptidyl peptidase IV (EC 3.4.14.X) in biopsies from proximal jejunum and distal ileum were studied by quantitative crossed immunoelectrophoresis and enzymatic assays in obese patients one and six months after jejunoileal bypass operation and compared with peroperative levels. They were related to DNA and protein content. The protein/DNA ratio fell 28-43% postoperatively. Except for ileal lactase and sucrase all enzymes showed decreased levels when expressed per mg protein and an even more pronounced decrease when related to DNA. Lactase and sucrase levels in ileum were increased or unchanged. A constant correlation between the amount of immunoreactive enzyme protein and enzymatic activity was shown for all enzymes except maltase. The results suggest that the bypass operation is followed by an increased amount of enterocytes devoid of or low in enzymatic activity and protein content. The amounts of lactase and sucrase in ileum are increased in relation to the other enzymes. No immunoreactive enzymes with zero or depressed activity were detected.     

Structural basis for epibatidine selectivity at desensitized nicotinic receptors

The agonist binding sites of the fetal muscle nicotinic acetylcholine receptor are formed at the interfaces of alpha-subunits and neighboring gamma- and delta-subunits. When the receptor is in the nonconducting desensitized state, the alpha-gamma site binds the agonist epibatidine 200-fold more tightly than does the alpha-delta site. To determine the structural basis for this selectivity, we constructed gamma/delta-subunit chimeras, coexpressed them with complementary wild-type subunits in HEK 293 cells, and determined epibatidine affinity of the resulting complexes. The results reveal three determinants of epibatidine selectivity: gamma104-117/delta106-delta119, gamma164-171/delta166-177, and gammaPro190/deltaAla196. Point mutations reveal that three sequence differences within the gamma104-117/delta106-delta119 region are determinants of epibatidine selectivity: gammaLys104/deltaTyr106, gammaSer111/deltaTyr113, and gammaTyr117/deltaTyr119. In the delta-subunit, simultaneous mutation of these residues to their gamma equivalent produces high affinity, gamma-like epibatidine binding. However, converting gamma to delta affinity requires replacement of the gamma104-117 segment with delta sequence, suggesting interplay of residues in this region. The structural basis for epibatidine selectivity is explained by computational docking of epibatidine to a homology model of the alpha-gamma binding site.     

Method of preparing a low-diaphragm flap

Diaphragm flaps on the low diaphragm vessels cut by the method described were used in 39 patients for plasty of the stump of the main and lobe bronchus, tracheo-bronchial and inter-bronchial anastomosis, pericardium. In 38 (97.4%) out of 39 patients the diaphragm plasty proved to be effective, the mechanical and biological characteristics of the flap allowed the desired effect of plasty to be obtained. The method of cutting the low diaphragm flap used is simple, safe and allows the preparation of a good plasty material for different purposes in the thoracic surgery.     

On the role of Cro in lambda prophage induction

The lysogenic state of bacteriophage lambda is exceptionally stable yet the prophage is readily induced in response to DNA damage. This delicate epigenetic switch is believed to be regulated by two proteins; the lysogenic maintenance promoting protein CI and the early lytic protein Cro. First, we confirm, in the native configuration, the previous observation that the DNA loop mediated by oligomerization of CI bound to two distinct operator regions (O(L) and O(R)), increases repression of the early lytic promoters and is important for stable maintenance of lysogeny. Second, we show that the presence of the cro gene might be unimportant for the lysogenic to lytic switch during induction of the lambda prophage. We revisit the idea that Cro's primary role in induction is instead to mediate weak repression of the early lytic promoters.     

Immunogenicity of constitutively active V599EBRaf

Activating BRAF somatic missense mutations within the kinase domain are present in 60-66% of melanomas. The vast majority of these represent a single substitution of glutamate for valine (V599E). Here, we demonstrate spontaneous HLA-B*2705-restricted cytotoxic T-cell responses against an epitope derived from (V599E)BRaf. These T-cell responses were mutation specific as the corresponding epitope derived from wild-type BRaf was not recognized. The loss of the (V599E)BRAF genotype during progression from primary to metastatic melanoma in patients with (V599E)BRaf specific T-cell responses suggests an active immune selection of nonmutated melanoma clones by the tumor-bearing host.