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AbstractArterial blood gas (ABG) machines are vital tools in the assessment of critically ill patients. Current ABG point-of-care (POC) analysers provide information on concentrations of haemoglobin, glucose and electrolytes in addition to acid-base balance. Awaiting results from venous analysers may present a significant delay in diagnosis and management, thus reliance on arterial blood gas determination of these parameters is increasing. However, published data on the concordance between the two modalities are limited. This study aims to assess the concordance of ABG machines in analysing haemoglobin, glucose and electrolyte concentrations compared to standard venous analysers as the gold standard. Results from 100 patients undergoing ABG analysis and simultaneous venous sampling without therapeutic intervention between sampling were compared. Differences in haemoglobin, glucose, sodium and potassium concentrations were determined and analysed using statistical software (Statview). There was a significant difference (P<0.02, paired signed test) in the mean haemoglobin concentration between the two modalities of 0.91 g/dL (range: 0–4.3 g/dL). Mean discrepancy in glucose concentrations was 1.16 mmol/L (range: 0-10.5 mmol/L; P<0.012, paired-signed test). Sodium and potassium showed no significant difference within the physiological range. At higher concentrations of potassium (>5 mmol/L), ABG readings varied significantly (P<0.0013, paired sign test) from standard venous estimates (mean difference: 0.44 mmol/L). Arterial blood gas analysers are invaluable for rapid assessment of critically ill patients; however, estimations of haemoglobin, glucose and potassium concentrations (>5 mmol/L) obtained from such machines should be interpreted with caution and confirmed using standard venous samples.

We have identified a Drosophila homolog of the DNA replication initiation inhibitor Geminin (Dm geminin) and show that it has all of the properties of Xenopus and human Geminin. During Drosophila development, Dm Geminin is present in cycling cells; protein accumulates during S phase and is degraded at the metaphase to anaphase transition. Overexpression of Dm geminin in embryos inhibits DNA replication, but cells enter mitosis arresting in metaphase, as in dup (cdt1) mutants, and undergo apoptosis. Overexpression of Dm Geminin also induces ectopic neural differentiation. Dm geminin mutant embryos exhibit anaphase defects at cycle 16 and increased numbers of S phase cells later in embryogenesis. In a partially female-sterile Dm geminin mutant, excessive DNA amplification in the ovarian follicle cells is observed. Our data suggest roles for Dm Geminin in limiting DNA replication, in anaphase and in neural differentiation.

Caspases are main effectors of apoptosis in metazoans. Genome analysis indicates that there are seven caspases in Drosophila, six of which have been previously characterized. Here we describe the cloning and characterization of the last Drosophila caspase, DAMM. Similar to mammalian effector caspases, DAMM lacks a long prodomain. We show that the DAMM precursor, along with the caspases DRONC and DECAY, is partially processed in cells undergoing apoptosis. Recombinant DAMM produced in Escherichia coli shows significant catalytic activity on a pentapeptide caspase substrate. Low levels of damm mRNA are ubiquitously expressed in Drosophila embryos during early stages of development. Relatively high levels of damm mRNA are detected in larval salivary glands and midgut, and in adult egg chambers. Ectopic expression of DAMM in cultured cells induces apoptosis, and similarly, transgenic overexpression of DAMM, but not of a catalytically inactive DAMM mutant, in Drosophila results in a rough eye phenotype. We demonstrate that expression of the catalytically inactive DAMM mutant protein significantly suppresses the rough eye phenotype due to the overexpression of HID, suggesting that DAMM may be required in a hid-mediated cell death pathway.

Caspases are key effectors of programmed cell death in metazoans. In Drosophila, four caspases have been described so far. Here we describe the identification and characterization of the fifth Drosophila caspase, DECAY. DECAY shares a high degree of homology with the members of the mammalian caspase-3 subfamily, particularly caspase-3 and caspase-7. DECAY lacks a long prodomain and thus appears to be a class II effector caspase. Ectopic expression of DECAY in cultured cells induces apoptosis. Recombinant DECAY exhibited substrate specificity similar to the mammalian caspase-3 subfamily. Low levels of decay mRNA are ubiquitously expressed in Drosophila embryos during early stages of development but its expression becomes somewhat spatially restricted in some tissues. During oogenesis decay mRNA was detected in egg chambers of all stages consistent with a role for DECAY in apoptosis of nurse cells. Relatively high levels of decay mRNA are expressed in larval salivary glands and midgut, two tissues which undergo histolysis during larval/pupal metamorphosis, suggesting that DECAY may play a role in developmentally programmed cell death in Drosophila.

Expression of the human homeobox gene HB24 in the cytotrophoblast stem cell population in rst-trimester human placenta was investigated. HB24expression was downregulated after cytotrophoblast had differentiated into syncytiotrophoblast. Expression of HB24 was also detected in rst-trimester invasive extravillous cytotrophoblast cells. In term placenta, HB24 expression was detected in residual cytotrophoblast cells and in syncytiotrophoblast. Northern analysis revealed two HB24 transcripts in rst-trimester placenta of approximately 2·5 kb and 5·3 kb. Ribonuclease protection assays were used to conrm expression of HB24 in rst-trimester and term placenta and also to provide evidence that HB24 is downregulated in choriocarcinoma cell lines. In addition to being required for differentiation of the haematopoietic cell lineage, HB24 may be required for differentiation of the extra-embryonic trophoblast cell lineage. Extra keywords: choriocarcinoma, chorionic villous, cytotrophoblast, homeodomain, syncytio- trophoblast.