The finding that C9-deficient sera (C9D) can kill serum sensitive strains of Gram-negative bacteria by us and other investigators, questions the role of C9 in the membrane attack complex as necessary for cell death. In these studies we have demonstrated that C5b-8 complexes generated on E. coli J5 during incubation in C9-depleted and C9-neutralized sera are effective in killing Gram-negative bacteria. In the same study, we extended our investigations to show that the deposition of C5b-7 complexes (from C8-deficient [C8D], C8 depleted and C8-neutralized sera) is also effective in killing Gram-negative bacteria. In all cases, these studies demonstrated that when E. coli J5 was incubated with C8D, C9D and pooled normal human serum [PNHS], deposited C5b-9 complexes from PNHS produced more killing than C5b-7 or C5b-8 complexes alone. These experiments clearly demonstrated that C5b-7 and C5b-8 complexes are bactericidal and that multimeric C9 within C5b-9 is not an absolute requirement for inner membrane damage and cell death of Gram-negative bacteria.

SUMMARY. When grown in specified conditions and tested by a rocked-tile method, 40 of 41 isolates of two species of Aeromonas formed simultaneously at least two haemagglutinins among which were: (i) a mannose-sensitive haemagglutinin with strongest activity for guinea-pig or fowl red cells, formed by all of 31 isolates of A . hydrophila and 9 of 10 isolates of A. punctata ss. caviae; (ii) a haemagglutinin, sensitive to L-fucose or D-mannose, that reacted with human red cells and which was formed by all 41 isolates; and (iii) a mannose-resistant 'tanned red cell' haemagglutinin formed by 29 isolates of A. hydrophila and one isolate of A. punctata ss. caviae. Results emphasise that for the fullest possible identification of haemagglutinins produced by Aeromonas spp., strains should be cultured in a variety of conditions and tested with a wide range of red-cell species.

Background: Leadership of clinical trials confers national recognition and promotes academic advancement. We hypothesized that women would be underrepresented among principal investigators (PIs) of hip and knee arthroplasty clinical trials in the United States. Methods: A query of hip and knee arthroplasty clinical trials from 2015 to 2021 was performed on ClinicalTrials.gov. Clinical trials were included if they involved a U.S.-based orthopaedic-surgeon PI. We analyzed the sex representation of arthroplasty PIs among junior-level (assistant professor) and senior-level (associate or full professor) faculty. Participation-to-prevalence ratios (PPRs) were calculated by comparing the sex representation among arthroplasty PIs with that among academic arthroplasty faculty at institutions conducting hip and knee arthroplasty clinical trials. A PPR of <0.8 indicated underrepresentation and a PPR of >1.2 indicated overrepresentation. Results: A total of 157 clinical trials involving 192 arthroplasty PIs were included. Of these PIs, only 2 (1.0%) were women. PIs were mostly funded by academic institutions (66%) and industry (33%). U.S. federal sources funded a minority (1%) of PIs. Of the 243 male arthroplasty faculty who were eligible, 190 men (78.2%) served as PIs. In contrast, of the 17 female arthroplasty faculty who were eligible, only 2 women (11.8%) served as PIs (p < 0.001). Across the entire cohort of arthroplasty PIs, women were underrepresented (PPR = 0.16), whereas men were equitably represented (PPR = 1.06). Women were underrepresented at the assistant professor (PPR = 0.0), associate professor (PPR = 0.52), and full professor (PPR = 0.58) levels. Conclusions: Women were underrepresented among PIs of hip and knee arthroplasty clinical trials, which may lead to disparities in academic promotion and advancement. More research is needed to understand the potential barriers to female leadership of clinical trials. Greater awareness and engagement are needed to create sex equity in clinical trial leadership for hip and knee arthroplasty research. Clinical Relevance: The underrepresentation of women among arthroplasty PIs may lead to fewer options in surgical providers for patients and may limit access to musculoskeletal care for certain patient populations. A diverse arthroplasty workforce can promote attention to issues that disproportionately affect historically underrepresented and vulnerable patient populations.

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