The cytoplasmic N-termini of connexins have been implicated in protein trafficking, oligomerization and channel gating. To elucidate the role of the N-terminus in connexin37 (CX37), we studied mutant constructs containing partial deletions of its 23 N-terminal amino acids and a construct with a complete N-terminus in which residues 2-8 were replaced with alanines. All mutants containing nine or more N-terminal amino acids form gap junction plaques in transiently transfected HeLa cells, whereas most of the longer deletions do not. Although wild-type CX37 allowed intercellular transfer of microinjected neurobiotin in HeLa cells and formed conducting hemichannels in Xenopus oocytes, none of the mutant constructs tested show evidence of channel function. However, in coexpression experiments, N-terminal mutants that formed gap junction plaques potently inhibit hemichannel conductance of wild-type CX37 suggesting their co-oligomerization. We conclude that as much as half the length of the connexin N-terminus can be deleted without affecting formation of gap junction plaques, but an intact N-terminus is required for hemichannel gating and intercellular communication.

Objective: We evaluated the ability of minimally invasive, image-guided vacuum-assisted biopsy (VAB) to reliably diagnose a pathologic complete response in the breast (pCR-B). Summary Background Data: Neoadjuvant systemic treatment (NST) elicits a pathologic complete response in up to 80% of women with breast cancer. In such cases, breast surgery, the gold standard for confirming pCR-B, may be considered overtreatment. Methods: This multicenter, prospective trial enrolled 452 women presenting with initial stage 1-3 breast cancer of all biological subtypes. Fifty-four women dropped out; 398 were included in the full analysis. All participants had an imaging-confirmed partial or complete response to NST and underwent studyspecific image-guided VAB before guideline-adherent breast surgery. The primary endpoint was the false-negative rate (FNR) of VAB-confirmed pCR-B.Results: Image-guided VAB alone did not detect surgically confirmed residual tumor in 37 of 208 women [FNR, 17.8%; 95% confidence interval (CI), 12.8-23.7%]. Of these 37 women, 12 (32.4%) had residual DCIS only, 20 (54.1%) had minimal residual tumor (<5 mm), and 19 of 25 (76.0%) exhibited invasive cancer cellularity of 10%. In 19 of the 37 cases (51.4%), the false-negative result was potentially avoidable. Exploratory analysis showed that performing VAB with the largest needle by volume (7-gauge) resulted in no false-negative results and that combining imaging and imageguided VAB into a single diagnostic test lowered the FNR to 6.2% (95% CI, 3.4%-10.5%). Conclusions: Image-guided VAB missed residual disease more often than expected. Refinements in procedure and patient selection seem possible and necessary before omitting breast surgery.

SummaryBackgroundArthroplasty patients with complications may be sensitized to implant components.ObjectivesTo quantify patch test reactions to implant materials in aseptic cemented arthroplasty patients with complications, and to evaluate the benefit of late patch test reading at D6.MethodsAnalyses of patch test reactions to baseline series and bone cement components and of the questionnaire‐aided histories of 250 consecutive patients with suspected implant allergy were performed. Patch tests were read at D2, D3, and D6.ResultsThere were 187 positive reactions to the 29 allergens of the baseline series, and 52 to the seven allergens of the bone cement series. Forty‐nine of 250 patients reacted to the bone cement series. In contrast to ‘early allergens’ such as fragrance mix, late reading at D6 increased the number of positive reactions by 11/32 for nickel, 1/5 for cobalt, and 2/4 for chromium. With bone cement components, most reactions were to gentamicin (25 of 250 patients), and 17 of 25 appeared only at D6.ConclusionLate reading is useful for patch tests with metals and bone cement components. With only D2/D3 readings, 32 reactions to nickel, cobalt, chromium and bone cement components would have been missed. This underlines the utility of late reading in general and in complicated cemented arthroplasty patients, given the unexpectedly high number of gentamicin reactions.

We performed a combined approach to identify suspected allergy to knee arthroplasty (TKR): patch test (PT), lymphocyte transformation test (LTT), histopathology (overall grading; T- and B-lymphocytes, macrophages, and neutrophils), and semiquantitative Real-time-PCR-based periprosthetic inflammatory mediator analysis (IFNγ, TNFα, IL1-β, IL-2, IL-6, IL-8, IL-10, IL17, and TGFβ). We analyzed 25 TKR patients with yet unexplained complications like pain, effusion, and reduced range of motion. They consisted of 20 patients with proven metal sensitization (11 with PT reactions; 9 with only LTT reactivity). Control specimens were from 5 complicated TKR patients without metal sensitization, 12 OA patients before arthroplasty, and 8 PT patients without arthroplasty. Lymphocytic infiltrates were seen and fibrotic (Type IV membrane) tissue response was most frequent in the metal sensitive patients, for example, in 81% of the PT positive patients. The latter also had marked periprosthetic IFNγ expression. 8/9 patients with revision surgery using Ti-coated/oxinium based implants reported symptom relief. Our findings demonstrate that combining allergy diagnostics with histopathology and periprosthetic cytokine assessment could allow us to design better diagnostic strategies.