The principal neutralizing determinant (PND) of human immunodeficiency virus HIV-1 is part of a disulfide bridged loop in the third variable region of the external envelope protein, gp120. Analysis of the amino acid sequences of this domain from 245 different HIV-1 isolates revealed that the PND is less variable than thought originally. Conservation to better than 80 percent of the amino acids in 9 out of 14 positions in the central portion of the PND and the occurrence of particular oligopeptide sequences in a majority of the isolates suggest that there are constraints on PND variability. One constraining influence may be the structural motif (beta strand--type II beta turn--beta strand--alpha helix) predicted for the consensus PND sequence by a neural network approach. Isolates with a PND similar to the commonly investigated human T cell lymphoma virus IIIB (HTLV-IIIB) and LAV-1 (BRU) strains were rare, and only 14 percent of sera from 86 randomly selected HIV-1 seropositive donors contained antibodies that recognized the PND of these virus isolates. In contrast, over 65 percent of these sera reacted with peptides containing more common PND sequences. These results suggest that HIV vaccine immunogens chosen because of their similarity to the consensus PND sequence and structure are likely to induce antibodies that neutralize a majority of HIV-1 isolates.

The COVID-19 pandemic caused by SARS-CoV-2 is unprecedented in modern history. Its effects on social behavior and health care delivery have been dramatic. The resultant burden of disease and critical illness has outpaced the diagnostic, therapeutic, and health care professional resources of many clinics and hospitals. It continues to do so globally. The allocation of hospital beds and ventilators, personal protective equipment, investigational therapeutics, and other scarce resources has required difficult decisions. Clinical and surgical practices which are standard in normal times may not be standard or safe during the COVID-19 crisis. How can we best adapt as physicians and surgeons? What foundational ethical principles and systems of principle application can help guide our decision-making? Fortunately, a large body of work in medical ethics addresses these questions. Unfortunately, many surgeons and other health care professionals are probably not as familiar with these concepts. This brief communication is intended to provide a concise explanation of ethical considerations which readers may find helpful when addressing allocation of scarce resources and alterations in surgical care brought on by the current pandemic.

Strattice™ is safe and effective in repairing inguinal hernia, with comparable intra-operative and early postoperative morbidity to synthetic mesh. Long-term follow-up is necessary in order to know whether the clinical outcomes of Strattice are equivalent to standard synthetic mesh in patients undergoing Lichtenstein's hernioplasty.

Ethical considerations relevant to the implementation of new surgical technologies and techniques are explored and discussed in practical terms in this statement, including (1) How is the safety of a new technology or technique ensured?; (2) What are the timing and process by which a new technology or technique is implemented at a hospital?; (3) How are patients informed before undergoing a new technology or technique?; (4) How are surgeons trained and credentialed in a new technology or technique?; (5) How are the outcomes of a new technology or technique tracked and evaluated?; and (6) How are the responsibilities to individual patients and society at large balanced? The following discussion is presented with the intent to encourage thought and dialogue about ethical considerations relevant to the implementation of new technologies and new techniques in surgery.