Genetic determinants of micronucleus formation in vivo.

Genomic instability arising from defective responses to DNA damage1 or mitotic chromosomal imbalances2 can lead to the sequestration of DNA in aberrant extranuclear structures called micronuclei (MN). Although MN are a hallmark of ageing and diseases associated with genomic instability, the catalogue of genetic players that regulate the generation of MN remains to be determined. Here we analyse 997 mouse mutant lines, revealing 145 genes whose loss significantly increases (n = 71) or decreases (n = 74) MN formation, including many genes whose orthologues are linked to human disease. We found that mice null for Dscc1, which showed the most significant increase in MN, also displayed a range of phenotypes characteristic of patients with cohesinopathy disorders. After validating the DSCC1-associated MN instability phenotype in human cells, we used genome-wide CRISPR-Cas9 screening to define synthetic lethal and synthetic rescue interactors. We found that the loss of SIRT1 can rescue phenotypes associated with DSCC1 loss in a manner paralleling restoration of protein acetylation of SMC3. Our study reveals factors involved in maintaining genomic stability and shows how this information can be used to identify mechanisms that are relevant to human disease biology1.

Jdp2 downregulates Trp53 transcription to promote leukaemogenesis in the context of Trp53 heterozygosity.

We performed a genetic screen in mice to identify candidate genes that are associated with leukaemogenesis in the context of Trp53 heterozygosity. To do this we generated Trp53 heterozygous mice carrying the T2/Onc transposon and SB11 transposase alleles to allow transposon-mediated insertional mutagenesis to occur. From the resulting leukaemias/lymphomas that developed in these mice, we identified nine loci that are potentially associated with tumour formation in the context of Trp53 heterozygosity, including AB041803 and the Jun dimerization protein 2 (Jdp2). We show that Jdp2 transcriptionally regulates the Trp53 promoter, via an atypical AP-1 site, and that Jdp2 expression negatively regulates Trp53 expression levels. This study is the first to identify a genetic mechanism for tumour formation in the context of Trp53 heterozygosity.

The activating mutation R201C in GNAS promotes intestinal tumourigenesis in Apc(Min/+) mice through activation of Wnt and ERK1/2 MAPK pathways.

Somatically acquired, activating mutations of GNAS, the gene encoding the stimulatory G-protein Gsalpha subunit, have been identified in kidney, thyroid, pituitary, leydig cell, adrenocortical and, more recently, in colorectal tumours, suggesting that mutations such as R201C may be oncogenic in these tissues. To study the role of GNAS in intestinal tumourigenesis, we placed GNAS R201C under the control of the A33-antigen promoter (Gpa33), which is almost exclusively expressed in the intestines. The GNAS R201C mutation has been shown to result in the constitutive activation of Gsalpha and adenylate cyclase and to lead to the autonomous synthesis of cyclic adenosine monophosphate (cAMP). Gpa33(tm1(GnasR201C)Wtsi/+) mice showed significantly elevated cAMP levels and a compensatory upregulation of cAMP-specific phosphodiesterases in the intestinal epithelium. GNAS R201C alone was not sufficient to induce tumourigenesis by 12 months, but there was a significant increase in adenoma formation when Gpa33(tm1(GnasR201C)Wtsi/+) mice were bred onto an Apc(Min/+) background. GNAS R201C expression was associated with elevated expression of Wnt and extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase (ERK1/2 MAPK) pathway target genes, increased phosphorylation of ERK1/2 MAPK and increased immunostaining for the proliferation marker Ki67. Furthermore, the effects of GNAS R201C on the Wnt pathway were additive to the inactivation of Apc. Our data strongly suggest that activating mutations of GNAS cooperate with inactivation of APC and are likely to contribute to colorectal tumourigenesis.

Effect of an anaesthesia department led critical care outreach and acute pain service on postoperative serious adverse events.

UNLABELLED: We examined whether a combined critical care outreach and acute pain service comprising both medical and nursing staff from the Department of Anaesthesia would decrease the incidence of postoperative serious adverse events in a hospital with an established Medical Emergency Team. We called this combined service IMPACT: Inpatient Management of acute Pain and Advice on Clinical Treatment. We conducted a prospective, before-and-after trial with a baseline phase (319 patients) of standard acute pain management followed by the IMPACT phase (271 patients), during which the IMPACT team systematically reviewed high-risk postoperative patients for the first three days after their return to the general wards. The incidence of serious adverse events decreased from 23 events per 100 patients to 16 events per 100 patients. The 30-day mortality decreased from 9% to 3%, p = 0.004. An acute pain service providing critical care outreach may improve postoperative outcome but the workload is considerable.

Platelet transfusion for patients with cancer: clinical practice guidelines of the American Society of Clinical Oncology.

OBJECTIVE: To determine the most effective, evidence-based approach to the use of platelet transfusions in patients with cancer. OUTCOMES: Outcomes of interest included prevention of morbidity and mortality from hemorrhage, effects on survival, quality of life, toxicity reduction, and cost-effectiveness. EVIDENCE: A complete MedLine search was performed of the past 20 years of the medical literature. Keywords included platelet transfusion, alloimmunization, hemorrhage, threshold and thrombocytopenia. The search was broadened by articles from the bibliographies of selected articles. VALUES: Levels of evidence and guideline grades were rated by a standard process. More weight was given to studies that tested a hypothesis directly related to one of the primary outcomes in a randomized design. BENEFITS/HARMS/COST: The possible consequences of different approaches to the use of platelet transfusion were considered in evaluating a preference for one or another technique producing similar outcomes. Cost alone was not a determining factor. RECOMMENDATIONS: Appendix A summarizes the recommendations concerning the choice of particular platelet preparations, the use of prophylactic platelet transfusions, indications for transfusion in selected clinical situations, and the diagnosis, prevention, and management of refractoriness to platelet transfusion. VALIDATION: Five outside reviewers, the ASCO Health Services Research Committee, and the ASCO Board reviewed this document. SPONSOR: American Society of Clinical Oncology

Immunologic defects in young male patients with hepatitis-associated aplastic anemia.

Extensive immunologic studies were done in 97 patients with severe aplastic anemia between 1973 and 1979. Sixteen young male patients with hepatitis-associated aplastic anemia appeared to constitute a unique subset. Compared with most patients with aplastic anemia from other causes, these 16 patients had significant reductions in the mean values of circulating T lymphocytes, serum IgG and IgM, mitogen reactivity, and decreased cutaneous hypersensitivity. The ratio of peripheral blood helper to suppressor T lymphocytes identified by monoclonal antibodies was within normal limits in 3 patients studied with hepatitis-associated aplastic anemia. Interestingly, the ratio was low (less than 1) in 3 of 7 patients studied with aplastic anemia from other causes, although the mean for these 7 patients was normal. These data suggest that patients in this subset with hepatitis-associated severe aplastic anemia have a severe immunodeficiency. Whether this immunodeficiency is the cause or result of the hepatitis or aplastic anemia, or both, is unknown.

Lymphocyte dysfunction in chronic graft-versus-host disease.

Three recipients of HLA-identical bone marrow transplants developed chronic graft-versus-host disease (cGVHD) and hypergammaglobulinemia. All three had evidence of abnormal B-lymphocyte function, including a polyclonal increase in immunoglobulins (Ig), antinuclear antibodies, rheumatoid factor, lymphocytotoxins, and increased immune complexes. T-lymphocyte function was also abnormal, including decreased mitogen reactivity and delayed cutaneous hypersensitivity. The cellular basis of these immune abnormalities was studied in an in vitro system in which we analyzed spontaneous pokeweed mitogen (PWM) driven Ig synthesis. Multiple defects in both T- and B-lymphocyte function were detected. In contrast to normal B cells, circulating B cells from all three patients with cGVHD spontaneously synthesized in vitro greater than 200 ng of IgG and in two of the three greater than 175 ng of IgM. This increase in spontaneous Ig synthesis was not due to a deficiency of regulatory cells, since T cells from the three patients suppressed spontaneous Ig synthesis in a normal fashion. In contrast to this increased spontaneous Ig synthesis, the response of the patients' B cells to PWM-driven Ig synthesis was normal. Using the PWM system we demonstrated several defects in these patients' T cells, including increased suppressor activity and decreased helper cell activity. These data indicate that some patients with cGVHD have multiple defects in both T- and B-cell function that may contribute to their profound immune deficiency.

Fatal veno-occlusive disease of the liver following high-dose 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and autologous bone marrow transplantation.

Veno-occlusive disease of the liver has recently been reported to occur in patients receiving multiagent chemotherapy together with total-body irradiation and bone marrow transplantation for malignancies. Reported is a case of a 22-year-old woman with disseminated diffuse histiocytic lymphoma in whom fatal hepatic veno-occlusive disease developed two and one-half weeks following high-dose 1,3-bis(2-chloroethyl)-1-nitrosourea) (BCNU) therapy and autologous bone marrow transplantation. This appears to be the first report of this entity in association with high-dose BCNU employed as a single chemotherapeutic agent.