Körber (Germany)

Neben Staat und Zivilgesellschaft spielen Unternehmen bei der Bewaltigung gesellschaftlicher Herausforderungen eine wichtige Rolle. Im Rahmen von Corporate-Citizenship-Programmen bundeln sie ihre gesellschaftsbezogenen Aktivitaten zum Wohl des Gemeinwesens. Corporate Volunteering, also der gemeinwohlorientierte Einsatz von Mitarbeitern, gewinnt dabei zunehmend an Bedeutung. Die Programme sind hinsichtlich des zeitlichen Umfangs, der eingebrachten Unternehmensressourcen und der Art des Engagements auserst vielfaltig. Insbesondere kompetenzbasiertes Engagement bietet hier ein echtes Win-win-win-Potenzial fur das Gemeinwesen, die Beschaftigten und das Unternehmen. Am Beispiel der gemeinnutzigen Mittlerorganisation startsocial, die soziale Initiativen und Mitarbeiter von Unternehmen zusammenbringt, werden Chancen und Herausforderungen dieser Engagementform aufgezeigt und Empfehlungen fur die Praxis formuliert.

We report the first solvate structure of the silicide anion Si44–, which provides circumstantial evidence of the stability of the highly charged anion in liquid ammonia solutions. The solvate Rb1.2K2.8Si4·7NH3 crystallized from a mixture of the ternary compound K6Rb6Si17 with the transition metal complex [(C6H5)3P]2Ni(CO)2 [bis(triphenylphosphine)dicarbonylnickel] in the presence of the chelating agents 18‐crown‐6 (1,4,7,10,13,16‐hexaoxacyclooctadecane) and [2.2.2]cryptand (4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane) in liquid ammonia. Single X‐ray diffraction analysis confirms the presence of the Si44– anion in the crystal structure of Rb1.2K2.8Si4·7NH3, which represents the first solvate compound of the naked tetrasilicide tetraanion. All five crystallographically independent cation positions show mixed occupancy by Rb+ and K+.

The mechanism of the progressive loss of CD4+ T lymphocytes, which underlies the development of AIDS in human immunodeficiency virus (HIV-1)-infected individuals, is unknown. Animal models, such as the infection of Old World monkeys by simian-human immunodeficiency virus (SHIV) chimerae, can assist studies of HIV-1 pathogenesis. Serial in vivo passage of the nonpathogenic SHIV-89.6 generated a virus, SHIV-89.6P, that causes rapid depletion of CD4+ T lymphocytes and AIDS-like illness in monkeys. SHIV-KB9, a molecularly cloned virus derived from SHIV-89.6P, also caused CD4+ T-cell decline and AIDS in inoculated monkeys. It has been demonstrated that changes in the envelope glycoproteins of SHIV-89.6 and SHIV-KB9 determine the degree of CD4+ T-cell loss that accompanies a given level of virus replication in the host animals (G. B. Karlsson et. al., J. Exp. Med. 188:1159-1171, 1998). The envelope glycoproteins of the pathogenic SHIV mediated membrane fusion more efficiently than those of the parental, nonpathogenic virus. Here we show that the minimal envelope glycoprotein region that specifies this increase in membrane-fusing capacity is sufficient to convert SHIV-89.6 into a virus that causes profound CD4+ T-lymphocyte depletion in monkeys. We also studied two single amino acid changes that decrease the membrane-fusing ability of the SHIV-KB9 envelope glycoproteins by different mechanisms. Each of these changes attenuated the CD4+ T-cell destruction that accompanied a given level of virus replication in SHIV-infected monkeys. Thus, the ability of the HIV-1 envelope glycoproteins to fuse membranes, which has been implicated in the induction of viral cytopathic effects in vitro, contributes to the capacity of the pathogenic SHIV to deplete CD4+ T lymphocytes in vivo.