General boundary conditions for the envelope function in multiband k.p model

We have derived general boundary conditions (BC) for the multiband envelope functions (which do not contain spurious solutions) in semiconductor heterostructures with abrupt heterointerfaces. These BC require the conservation of the probability flux density normal to the interface and guarantee that the multiband Hamiltonian be self--adjoint. The BC are energy independent and are characteristic properties of the interface. Calculations have been performed of the effect of the general BC on the electron energy levels in a potential well with infinite potential barriers using a coupled two band model. The connection with other approaches to determining BC for the envelope function and to the spurious solution problem in the multiband k.p model are discussed.Comment: 15 pages, 2 figures; to be published in Phys. Rev. B 65, March 15 issue 200

Transmission of Human Immunodeficiency Virus Type 1 from a Seronegative Organ and Tissue Donor

Abstract BACKGROUND Since 1985, donors of organs or tissues for transplantation in the United States have been screened for human immunodeficiency virus type 1 (HIV-1), and more than 60,000 organs and 1 million tissues have been transplanted. We describe a case of transmission of HIV-1 by transplantation of organs and tissues procured between the time the donor became infected and the appearance of antibodies. The donor was a 22-year-old man who died 32 hours after a gunshot wound; he had no known risk factors for HIV-1 infection and was seronegative. METHODS We reviewed the processing and distribution of all the transplanted organs and tissues, reviewed the medical histories of the donor and HIV-1—infected recipients, tested stored donor lymphocytes for HIV-1 by viral culture and the polymerase chain reaction, and tested stored serum samples from four organ recipients for HIV-1 antigen and antibody. RESULTS HIV-1 was detected in cultured lymphocytes from the donor. Of 58 tissues and organs obtained from the donor, 52 could be accounted for by the hospitals that received them. Of the 48 identified recipients, 41 were tested for HIV-1 antibody. All four recipients of organs and all three recipients of unprocessed fresh-frozen bone were infected with HIV-1. However, 34 recipients of other tissues — 2 receiving corneas, 3 receiving lyophilized soft tissue, 25 receiving ethanol-treated bone, 3 receiving dura mater treated with gamma radiation, and 1 receiving marrow-evacuated, fresh-frozen bone — tested negative for HIV-1 antibody. Despite immunosuppressive chemotherapy, HIV-1 antibody appeared between 26 and 54 days after transplantation in the three organ recipients who survived more than 4 weeks. CONCLUSIONS Although rare, transmission of HIV-1 by seronegative organ and tissue donors can occur. Improvements in the methods used to screen donors for HIV-1, advances in techniques of virus inactivation, prompt reporting of HIV infection in recipients, and accurate accounting of distributed allografts would help to reduce further this already exceedingly low risk. (N Engl J Med 1992;326:726–32.

Molecular Features of Cancers Exhibiting Exceptional Responses to Treatment

A small fraction of cancer patients with advanced disease survive significantly longer than patients with clinically comparable tumors. Molecular mechanisms for exceptional responses to therapy have been identified by genomic analysis of tumor biopsies from individual patients. Here, we analyzed tumor biopsies from an unbiased cohort of 111 exceptional responder patients using multiple platforms to profile genetic and epigenetic aberrations as well as the tumor microenvironment. Integrative analysis uncovered plausible mechanisms for the therapeutic response in nearly a quarter of the patients. The mechanisms were assigned to four broad categories—DNA damage response, intracellular signaling, immune engagement, and genetic alterations characteristic of favorable prognosis—with many tumors falling into multiple categories. These analyses revealed synthetic lethal relationships that may be exploited therapeutically and rare genetic lesions that favor therapeutic success, while also providing a wealth of testable hypotheses regarding oncogenic mechanisms that may influence the response to cancer therapy. Profiling multi-platform genomics of 110 cancer patients with an exceptional therapeutic response, Wheeler et al. identify putative molecular mechanisms explaining this survival phenotype in ∼23% of cases. Therapeutic success is related to rare molecular features of responding tumors, exploiting synthetic lethality and oncogene addiction