Olanzapine for the Prevention of Postdischarge Nausea and Vomiting after Ambulatory Surgery: A Randomized Controlled Trial.

BACKGROUND: Postdischarge nausea and vomiting after ambulatory surgery is a common problem that is not adequately addressed in current practice. This prospective, randomized, double-blind, parallel-group, placebo-controlled study was designed to test the hypothesis that oral olanzapine is superior to placebo at preventing postdischarge nausea and vomiting. METHODS: In a single-center, double-blind, randomized, placebo-controlled trial, the authors compared a single preoperative dose of olanzapine 10 mg to placebo, in adult female patients 50 years old or less, undergoing ambulatory gynecologic or plastic surgery with general anesthesia. All patients received standard antiemetic prophylaxis with dexamethasone and ondansetron. The primary composite outcome was nausea and/or vomiting in the 24 h after discharge. Secondary outcomes included severe nausea, vomiting, and side effects. RESULTS: A total of 140 patients were randomized and evaluable. The primary outcome occurred in 26 of 69 patients (38%) in the placebo group and in 10 of 71 patients (14%) in the olanzapine group (relative risk, 0.37; 95% CI, 0.20 to 0.72; P = 0.003). Severe nausea occurred in 14 patients (20%) in the placebo group and 4 patients (6%) in the olanzapine group (relative risk, 0.28; 95% CI, 0.10 to 0.80). Vomiting occurred in eight patients (12%) in the placebo group and two patients (3%) in the olanzapine group (relative risk, 0.24; 95% CI, 0.05 to 1.10). The median score for sedation (scale 0 to 10, with 10 being highest) in the 24 h after discharge was 4 (interquartile range, 2 to 7) in the placebo group and 6 (interquartile range, 3 to 8) in the olanzapine group (P = 0.023). CONCLUSIONS: When combined with ondansetron and dexamethasone, the addition of olanzapine relative to placebo decreased the risk of nausea and/or vomiting in the 24 hafter discharge from ambulatory surgery by about 60% with a slight increase in reported sedation.

HIV type 1 infection of plasmacytoid and myeloid dendritic cells is restricted by high levels of SAMHD1 and cannot be counteracted by Vpx.

Dendritic cells are professional antigen-presenting cells of the immune system and are major producers of type-I interferon. Their role in HIV-1 infection is not well understood. They express CD4 and CCR5 yet appear to be resistant to infection. In culture, infection of the cells with HIV-1 is inhibited by the host cell restriction factor SAMHD1. Lentiviruses such as HIV-2/SIVmac counteract the restriction by encoding Vpx, a virion-packaged accessory protein that induces the proteasomal degradation of SAMHD1. In this study we investigated SAMHD1-mediated restriction in the two major dendritic cell subsets: plasmacytoid dendritic cells (pDC) and myeloid dendritic cells (mDC). The cells were highly resistant to HIV-1 and expressed high levels of SAMHD1. SAMHD1 amino acid residue T592, a target of CDK1 phosphorylation, was unphosphorylated, corresponding to the antiviral form of the enzyme. The resistance to infection was not counteracted by Vpx and SAMHD1 was not degraded in these cells. Treatment of pDCs with a cocktail of antibodies that blocked type-I interferon signaling partially restored the ability of Vpx to induce SAMHD1 degradation and caused the cells to become partially permissive to infection. pDCs and mDCs responded to HIV-1 virions by inducing an innate immune response but did not appear to sense newly produced Gag protein. The findings suggest that in vivo, dendritic cells serve as sentinels to alert the immune system to the virus but do not themselves become infected by virtue of high levels of SAMHD1.

Inhibition of CUL4A Neddylation causes a reversible block to SAMHD1-mediated restriction of HIV-1.

The deoxynucleoside triphosphohydrolase SAMHD1 restricts retroviral replication in myeloid cells. Human immunodeficiency virus type 2 (HIV-2) and a simian immunodeficiency virus from rhesus macaques (SIVmac) encode Vpx, a virion-packaged accessory protein that counteracts SAMHD1 by inducing its degradation. SAMHD1 is thought to work by depleting the pool of intracellular deoxynucleoside triphosphates but has also been reported to have exonuclease activity that could allow it to degrade the viral genomic RNA or viral reverse-transcribed DNA. To induce the degradation of SAMHD1, Vpx co-opts the cullin4a-based E3 ubiquitin ligase, CRL4. E3 ubiquitin ligases are regulated by the covalent attachment of the ubiquitin-like protein Nedd8 to the cullin subunit. Neddylation can be prevented by MLN4924, a drug that inhibits the nedd8-activating enzyme. We report that MLN4924 inhibits the neddylation of CRL4, blocking Vpx-induced degradation of SAMHD1 and maintaining the restriction. Removal of the drug several hours postinfection released the block. Similarly, Vpx-containing virus-like particles and deoxynucleosides added to the cells more than 24 h postinfection released the SAMHD1-mediated block. Taken together, these findings support deoxynucleoside triphosphate pool depletion as the primary mechanism of SAMHD1 restriction and argue against a nucleolytic mechanism, which would not be reversible.

The Vpx lentiviral accessory protein targets SAMHD1 for degradation in the nucleus.

Sterile alpha motif domain- and HD domain-containing protein 1 (SAMHD1) is a deoxynucleoside triphosphohydrolase that restricts the replication of lentiviruses in myeloid cells by hydrolyzing the cellular deoxynucleotide triphosphates to a level below that which is required for reverse transcription. Human immunodeficiency virus type 2 (HIV-2) and some simian immunodeficiency viruses (SIVs) encode the accessory protein viral protein X (Vpx) that counteracts SAMHD1. Vpx recruits SAMHD1 to a cullin4A-RING E3 ubiquitin ligase (CRL4), which targets the enzyme for proteasomal degradation. Vpx and SAMHD1 both localize to the nucleus of the cell. We identified the nuclear localization sequence (NLS) of SAMHD1 as a conserved KRPR sequence at amino acid residues 11 to 14. SAMHD1 lacking a functional NLS localized to the cytoplasm but retained its triphosphohydrolase and antiviral activities. However, cytoplasmic SAMHD1 was resistant to Vpx-induced degradation, and its antiviral activity was not counteracted by Vpx. Cytoplasmic SAMHD1 interacted with Vpx and retained it in the cytoplasm. The inhibition of nuclear export with leptomycin B did not impair the ability of Vpx to degrade SAMHD1. These findings suggest that SAMHD1 is targeted by Vpx for ubiquitination and degradation in the nucleus.