DinB (DNA polymerase IV), ImuBC and RpoS contribute to the generation of ciprofloxacin-resistance mutations in Pseudomonas aeruginosa.

We investigated the role(s) of the damage-inducible SOS response dinB and imuBC gene products in the generation of ciprofloxacin-resistance mutations in the important human opportunistic bacterial pathogen, Pseudomonas aeruginosa. We found that the overall numbers of ciprofloxacin resistant (CipR) mutants able to be recovered under conditions of selection were significantly reduced when the bacterial cells concerned carried a defective dinB gene, but could be elevated to levels approaching wild-type when these cells were supplied with the dinB gene on a plasmid vector; in turn, firmly establishing a role for the dinB gene product, error-prone DNA polymerase IV, in the generation of CipR mutations in P. aeruginosa. Further, we report that products of the SOS-regulated imuABC gene cassette of this organism, ImuB and the error-prone ImuC DNA polymerase, are also involved in generating CipR mutations in this organism, since the yields of CipR mutations were substantially decreased in imuB- or imuC-defective cells compared to wild-type. Intriguingly, we found that the mutability of a dinB-defective strain could not be rescued by overexpression of the imuBC genes. And similarly, overexpression of the dinB gene either only modestly or else failed to restore CipR mutations in imuB- or imuC-defective cells, respectively. Combined, these results indicated that the products of the dinB and imuBC genes were acting in the same pathway leading to the generation of CipR mutations in P. aeruginosa. In addition, we provide evidence indicating that the general stress response sigma factor σs, RpoS, is required for mutagenesis in this organism and is in part at least modulating the dinB (DNA polymerase IV)-dependent mutational process. Altogether, these data provide further insight into the complexity and multifaceted control of the mutational mechanism(s) contributing to the generation of ciprofloxacin-resistance mutations in P. aeruginosa.

DNA methylation changes following DNA damage in prostate cancer cells.

Many cancer therapies operate by inducing double-strand breaks (DSBs) in cancer cells, however treatment-resistant cells rapidly initiate mechanisms to repair damage enabling survival. While the DNA repair mechanisms responsible for cancer cell survival following DNA damaging treatments are becoming better understood, less is known about the role of the epigenome in this process. Using prostate cancer cell lines with differing sensitivities to radiation treatment, we analysed the DNA methylation profiles prior to and following a single dose of radiotherapy (RT) using the Illumina Infinium HumanMethylation450 BeadChip platform. DSB formation and repair, in the absence and presence of the DNA hypomethylating agent, 5-azacytidine (5-AzaC), were also investigated using γH2A.X immunofluorescence staining. Here we demonstrate that DNA methylation is generally stable following a single dose of RT; however, a small number of CpG sites are stably altered up to 14 d following exposure. While the radioresistant and radiosensitive cells displayed distinct basal DNA methylation profiles, their susceptibility to DNA damage appeared similar demonstrating that basal DNA methylation has a limited influence on DSB induction at the regions examined. Recovery from DSB induction was also similar between these cells. Treatment with 5-AzaC did not sensitize resistant cells to DNA damage, but rather delayed recruitment of phosphorylated BRCA1 (S1423) and repair of DSBs. These results highlight that stable epigenetic changes are possible following a single dose of RT and may have significant clinical implications for cancer treatment involving recurrent or fractionated dosing regimens.

Pathway Analysis of Fucoidan Activity Using a Yeast Gene Deletion Library Screen.

Fucoidan, the sulfated fucose-rich polysaccharide derived from brown macroalgae, was reported to display some anti-cancer effects in in vitro and in vivo models that included apoptosis and cell cycle arrest. The proposed mechanisms of action involve enhanced immune surveillance and direct pro-apoptotic effects via the activation of cell signaling pathways that remain largely uncharacterized. This study aimed to identify cellular pathways influenced by fucoidan using an unbiased genetic approach to generate additional insights into the anti-cancer effects of fucoidan. Drug⁻gene interactions of Undaria pinnatifida fucoidan were assessed by a systematic screen of the entire set of 4,733 halpoid Saccharomyces cerevsiae gene deletion strains. Some of the findings were confirmed using cell cycle analysis and DNA damage detection in non-immortalized human dermal fibroblasts and colon cancer cells. The yeast deletion library screen and subsequent pathway and interactome analysis identified global effects of fucoidan on a wide range of eukaryotic cellular processes, including RNA metabolism, protein synthesis, sorting, targeting and transport, carbohydrate metabolism, mitochondrial maintenance, cell cycle regulation, and DNA damage repair-related pathways. Fucoidan also reduced clonogenic survival, induced DNA damage and G1-arrest in colon cancer cells, while these effects were not observed in non-immortalized human fibroblasts. Our results demonstrate global effects of fucoidan in diverse cellular processes in eukaryotic cells and further our understanding about the inhibitory effect of Undaria pinnatifida fucoidan on the growth of human cancer cells.

Pandoraea fibrosis sp. nov., a novel Pandoraea species isolated from clinical respiratory samples.

Pandoraea species have been isolated from diverse environmental samples and are emerging important respiratory pathogens, particularly in people with cystic fibrosis (CF). In the present study, two bacterial isolates initially recovered from consecutive sputum samples collected from a CF patient and identified as Pandoraea pnomenusa underwent a polyphasic taxonomic analysis. The isolates were found to be Gram-negative, facultative anaerobic motile bacilli and subsequently designated as strains 6399T (=LMG29626T=DSM103228T) and 7641 (=LMG29627=DSM103229), respectively. Phylogenetic analysis based on 16S rRNA and gyrB gene sequences revealed that 6399T and 7641 formed a distinct phylogenetic lineage within the genus Pandoraea. Genome sequence comparison analysis indicated that strains 6399T and 7641 are clonal and share 100 % similarity, however, similarity to other type strains (ANIb 73.2-88.8 %, ANIm 83.5-89.9 % and OrthoANI 83.2-89.3 %) indicates that 6399T and 7641 do not belong to any of the reported type species. The major cellular fatty acids of 6399T were C16 : 0 (32.1 %) C17 : 0cyclo (18.7 %) and C18 : 1ω7c (14.5 %), while Q-8 was the only respiratory quinone detected. The major polar lipids identified were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The genomic DNA G+C content of 6399T was 62.9 (mol%). Strain 6399T can be differentiated from other members of Pandoraea by the absence of C19 : 0ω8c cyclo and by the presence of C17 : 0ω8c cyclo. Together our data show that the bacterial strains 6399T and 7641 represent a novel species of the genus Pandoraea, for which the name Pandoraea fibrosis sp. nov. is proposed (type strain 6399T).

Learning global health: a pilot study of an online collaborative intercultural peer group activity involving medical students in Australia and Indonesia.

BACKGROUND: There is limited research to inform effective pedagogies for teaching global health to undergraduate medical students. Theoretically, using a combination of teaching pedagogies typically used in 'international classrooms' may prove to be an effective way of learning global health. This pilot study aimed to explore the experiences of medical students in Australia and Indonesia who participated in a reciprocal intercultural participatory peer e-learning activity (RIPPLE) in global health. METHODS: Seventy-one third year medical students (49 from Australia and 22 from Indonesia) from the University of Tasmania (Australia) and the University of Nusa Cendana (Indonesia) participated in the RIPPLE activity. Participants were randomly distributed into 11 intercultural 'virtual' groups. The groups collaborated online over two weeks to study a global health topic of their choice, and each group produced a structured research abstract. Pre- and post-RIPPLE questionnaires were used to capture students' experiences of the activity. Descriptive quantitative data were analysed with Microsoft Excel and qualitative data were thematically analysed. RESULTS: Students' motivation to volunteer for this activity included: curiosity about the innovative approach to learning; wanting to expand knowledge of global health; hoping to build personal and professional relationships; and a desire to be part of an intercultural experience. Afer completing the RIPPLE program, participants reported on global health knowledge acquisition, the development of peer relationships, and insight into another culture. Barriers to achieving the learning outcomes associated with RIPPLE included problems with establishing consistent online communication, and effectively managing time to simultaneously complete RIPPLE and other curricula activities. CONCLUSIONS: Medical students from both countries found benefits in working together in small virtual groups to complement existing teaching in global health. However, our pilot study demonstrated that while intercultural collaborative peer learning activities like RIPPLE are feasible, they require robust logistical support and an awareness of the need to manage curriculum alignment in ways that facilitate more effective student engagement.

Pandoraea pnomenusa Isolated from an Australian Patient with Cystic Fibrosis.

Pandoraea species are considered as emerging pathogens in people with cystic fibrosis (CF). The contribution of these organisms to disease progression in CF patients is not fully understood owing in large measure to the scant reports in clinical and research literature describing their colonization of CF patients and their associated virulence determinants. In an effort to increase awareness and evidence for Pandoraea spp. infection in people with CF, and to stimulate research aimed at unraveling the pathogenic properties of Pandoraea, we report a case of a 26-year-old Australian (Tasmanian) man with CF who was chronically infected with Pandoraea pnomenusa for at least one year prior to his death from respiratory failure. In addition, we describe for the first time evidence suggesting that this bacterium is a facultative anaerobe and report on the availability of a whole genome sequence for this organism. To the best of our knowledge, this report represents only the second clinical case study of P. pnomenusa infection in the world, and the first in an Australian CF patient.

Functionalized polyanilines disrupt Pseudomonas aeruginosa and Staphylococcus aureus biofilms.

The purpose of the present study was to investigate the antimicrobial effects of functionalized polyanilines (fPANIs) against stationary phase cells and biofilms of Pseudomonas aeruginosa and Staphylococcus aureus using homopolymer of sulfanilic acid (poly-SO3H) as a model. The chemically synthesized poly-SO3H was characterized using Fourier Transform Infra-Red (FTIR) and Ultraviolet-Visible (UV-Vis) spectroscopies. The molecular weight (Mw) and elemental analysis of homopolymer poly-SO3H were also examined. We found that poly-SO3H was bactericidal against stationary phase cells of P. aeruginosa and S. aureus at a concentration of 20 mgml(-1). Surprisingly, we discovered that the same concentration (20 mgml(-1)) of poly-SO3H significantly disrupted and killed bacterial cells present in pre-established forty-eight hour static biofilms of these organisms, as shown by crystal violet and bacterial live/dead fluorescence staining assays. In support of these data, poly-SO3H extensively diminished the expression of bacterial genes related to biofilm formation in stationary phase cells of P. aeruginosa, and seemed to greatly reduce the amount of the quorum sensing molecule N-(3-oxododecanoyl)-l-homoserine lactone (3OC12-HSL) able to be recovered from biofilms of this organism. Furthermore, we found that poly-SO3H was able to effectively penetrate and kill cells in biofilms formed by the P. aeruginosa (AESIII) isolate derived from the sputum of a cystic fibrosis patient. Taken together, the results of the present study emphasise the broad antimicrobial activities of fPANI, and suggest that they could be developed further and used in some novel ways to construct medical devices and/or industrial equipment that are refractory to colonization by biofilm-forming bacteria.

Genome Sequences of Two Pandoraea pnomenusa Isolates Recovered 11 Months Apart from a Cystic Fibrosis Patient.

Pandoraea is an emerging respiratory pathogen capable of causing chronic lung infections in people with cystic fibrosis (CF), but the clinical significance of this infection is ambiguous. We have sequenced and annotated the genomes of two multidrug-resistant Pandoraea pnomenusa isolates recovered 11 months apart from the same CF patient.

Air Transmission Comparison of the Affinity Fusion Oxygenator with an Integrated Arterial Filter to the Affinity NT Oxygenator with a Separate Arterial Filter.

Arterial filters used in the extracorporeal circuit (ECC) have been shown to minimize cerebral injury by capturing particulate matter and microbubbles. We clinically use the Affinity NT oxygenator with an Affinity arterial filter attached ("Affinity system"). The new Affinity Fusion oxygenator ("Fusion") incorporates integrated arterial filtering. Our aim was to determine if the Fusion oxygenator was as safe as the Affinity system in terms of relative microbubble transmission of introduced air. A recirculating in vitro circuit primed with blood was used to compare the Fusion with the Affinity system. Microbubbles were detected using a GAMPT BC100 Doppler in the oxygenator-arterial filter outflow line. Measurements were taken 1 minute before and 3 minutes after bolusing 30 mL air proximal to the venous reservoir while altering pump flow rates (3 L/min; 5 L/min). Both the Fusion and Affinity system transmitted microbubbles during air injection. Microbubble volume transmitted at 5 L/min pump flow was significantly greater than at 3 L/min in both systems. The Fusion tended to transmit fewer bubbles, less bubble volume, and smaller sized bubbles than the Affinity system. Under the parameters of this in vitro study, the Affinity Fusion oxygenator with an integrated arterial filter is as safe as the Affinity NT oxygenator with a separate arterial filter in terms of microbubble transmission. However, more research is needed to confirm this study's findings and generalizability to the clinical environment. As both oxygenator-arterial filter systems transmitted microbubbles during air introduction, it is important to develop strategies to minimize microbubble entry into the ECC.

Microbubble transmission during cardiotomy infusion of a hardshell venous reservoir with integrated cardiotomy versus a softshell venous reservoir with separated cardiotomy: an in vitro comparison.

An important mechanism for postoperative cognitive impairment after cardiac surgery using cardiopulmonary bypass (CPB) is microemboli. One component of the CPB circuit-the cardiotomy-is a major source of gaseous microemboli because it aspirates significant volumes of air with blood from the operative field and intracardiac chambers. Cardiotomies are either integrated within an open hardshell venous reservoir (IC-HSVR) or are a separate canister attached to a softshell collapsible venous reservoir bag (SC-SSVR). The purpose of this study was to compare the Medtronic IC-HSVR (Affinity NT CVR) with Medtronic's SC-SSVR (CB 1351, CBMVR 1600) in terms of relative microbubble transmission during cardiotomy infusion. A recirculating in vitro circuit primed with blood was used to compare the two cardiotomy-reservoir systems with the venous reservoir in the SC-SSVR further assessed in a fully closed or partially open state (SC-SSVR-closed; SC-SSVR-open). Microbubbles were detected using a GAMPT BC100 Doppler system in the outflow line of the venous reservoir. Measurements were taken before (baseline) and after aerated prime was pumped into the cardiotomy while altering pump flow rates (3 L/min; 5 L/min) and reservoir prime volumes (400 mL; 900 mL). Infusing cardiotomy blood into the venous reservoir was associated with an increase in microbubbles and bubble volume transmitted by both cardiotomy-reservoir systems with the magnitude rising with reduced prime volumes. The effect was markedly greater with the IC-HSVR. The IC-HSVR also transmitted larger bubbles, particularly with reduced prime volumes. There was no significant difference in microbubble transmission seen between the SC-SSVR-closed and SC-SSVR-open. The SC-SSVR transmits fewer microbubbles than the IC-HSVR during cardiotomy infusion and should be considered as the preferential system. Because both cardiotomy-reservoir systems transmitted microbubbles during cardiotomy infusion, particularly at the lower venous reservoir volume, it is important to use strategies to minimize cardiotomy microbubble infusion.

Pathogenesis of ataxia-telangiectasia: the next generation of ATM functions.

In 1988, the gene responsible for the autosomal recessive disease ataxia- telangiectasia (A-T) was localized to 11q22.3-23.1. It was eventually cloned in 1995. Many independent laboratories have since demonstrated that in replicating cells, ataxia telangiectasia mutated (ATM) is predominantly a nuclear protein that is involved in the early recognition and response to double-stranded DNA breaks. ATM is a high-molecular-weight PI3K-family kinase. ATM also plays many important cytoplasmic roles where it phosphorylates hundreds of protein substrates that activate and coordinate cell-signaling pathways involved in cell-cycle checkpoints, nuclear localization, gene transcription and expression, the response to oxidative stress, apoptosis, nonsense-mediated decay, and others. Appreciating these roles helps to provide new insights into the diverse clinical phenotypes exhibited by A-T patients-children and adults alike-which include neurodegeneration, high cancer risk, adverse reactions to radiation and chemotherapy, pulmonary failure, immunodeficiency, glucose transporter aberrations, insulin-resistant diabetogenic responses, and distinct chromosomal and chromatin changes. An exciting recent development is the ATM-dependent pathology encountered in mitochondria, leading to inefficient respiration and energy metabolism and the excessive generation of free radicals that themselves create life-threatening DNA lesions that must be repaired within minutes to minimize individual cell losses.

Microbubble generation and transmission of medtronic's affinity hardshell venous reservoir and collapsible venous reservoir bag: an in-vitro comparison.

Microemboli are implicated in neurological injury; therefore, the extracorporeal circuit (ECC) should not generate microbubbles or transmit introduced air. The venous reservoir is the first component in the ECC designed to remove introduced air. The purpose of this study was to investigate the relative safety of two kinds of adult venous reservoirs--the closed soft-shell venous reservoir (SSVR [Medtronic CBMVR 1600]) and the open hard-shell venous reservoir (HSVR [Affinity NT CVR])--in terms of microbubble generation and introduced air transmission. A recirculating in-vitro circuit was used to compare the two reservoirs with the SSVR further assessed in a fully closed or partially open state. Microbubbles were counted using a Hatteland CMD-10 Doppler in the outflow of the reservoirs before (microbubble generation) and after infusing 20 mL/min of air into the venous line (microbubble transmission) while altering pump flow rates (3 L/min; 5 L/min) and reservoir prime (200 mL; 700 mL). Negligible bubble generation was noted in the SSVRs at both flow rates and either reservoir volume. However, microbubble generation was significant in the HSVR at the higher flow rate of 5 L/min and lower reservoir volume of 200 mL. When infusing air, a flow of 3 L/min was associated with insignificant to small increases in microbubble transmission for all reservoirs. Conversely, infusing air while flowing at 5 L/min was associated with significantly more microbubble transmission for all reservoirs at both low and high reservoir volumes.The SSVR is as safe as the HSVR in microbubble handling as the generation and transmission of microbubbles by the SSVR is not more than the HSVR over a range of prime volumes and flow rates. As both reservoirs transmitted microbubbles at higher pump flow rates regardless of reservoir volumes, it is important to eliminate venous air entrainment during cardiopulmonary bypass.

Broad spectrum antimicrobial activity of functionalized polyanilines.

The antimicrobial properties of conductive functionalized polyanilines (fPANI) were investigated by exploring their interaction with bacterial cells. In sharp contrast to polyaniline (PANI), lower concentrations of fPANI were needed to strongly inhibit the growth of wild-type Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, as well as several antibiotic-resistant clinical pathogens. To gain an insight into how fPANI have an impact on cellular physiology we used a whole genome expression study in the model E. coli MG1655 strain exposed to a representative fPANI. The expression levels of 218 (∼5.1%) genes changed significantly. Moreover, we found that certain oxidative damage-responsive genes were strongly induced, while genes potentially involved in energy metabolism and transport and in forming bacterial cell walls and stress-resistant cellular communities (biofilms) were repressed. Taken together, our results appear to indicate that the antimicrobial effects of fPANI, in part at least, might stem from their ability to target the operations of multiple and diverse cellular processes, and suggest that fPANI could be useful ingredients for biomaterials used in the development of food packaging and medical devices.

Getting it right: optimizing transfusion management during the procedure.

There is little doubt that blood transfusions have saved many lives in cases of acute hypovolemia and anemia, but both the literature and practitioners still do not agree as to what the appropriate indicators for transfusion are in a cardiac surgical patient. Furthermore, there are those who claim that the benefit of blood transfusions has never been conclusively demonstrated, and evidence of transfusion related harm continues to accumulate. Cardiac surgical patients may be transfused not only because of bleeding but also due to hemodilution from preoperative and intraoperative intravenous fluids and pump primes in conjunction with a possible preoperative anemia. Getting transfusion right to improve our practice has to be approached multifactorially. The use of prophylactic dosing of blood products has been suggested to be ineffective in reducing blood loss. There are many factors that impact transfusion rates including determining the optimal hematocrit where it is highly unlikely that one figure will be applicable to all patients. The formulation of transfusion guidelines and algorithms that have been agreed upon by all practitioners involved in the care of cardiac surgical patients may have a positive effect-if everyone agrees to transfuse patients via the formulated guidelines or algorithms. Importantly, no one individual should be able make the decision on whether a patient requires a blood transfusion-it must at all times be a team decision, whether in the operating room or intensive care unit.

Transcriptional networks in S. cerevisiae linked to an accumulation of base excision repair intermediates.

Upon exposure to DNA damaging agents, Saccharomyces cerevisiae respond by activating a massive transcriptional program that reflects the fact that "DNA damaging" agents also damage other cellular macromolecules. To identify the transcriptional response that is specific to DNA damage, we have modulated the first two enzymes in the base excision repair (BER) pathway generating yeast strains with varied levels of the repair intermediates, abasic sites or strand breaks. We show that the number of abasic sites is significantly increased when the 3-methyladenine DNA glycosylase (Mag): AP endonuclease (Apn1) ratio is increased and that spontaneous frame shift mutation is considerably elevated when either Mag, or Mag plus Apn1, expression is elevated. Expression profiling identified 633 ORFs with differential expression associated with BER modulation. Analysis of transcriptional networks associated with the accumulation of DNA repair intermediates identifies an enrichment for numerous biological processes. Moreover, most of the BER-activated transcriptional response was independent of the classical yeast environmental stress response (ESR). This study highlights that DNA damage in the form of abasic sites or strand breaks resulting from BER modulation is a trigger for substantial genome-wide change and that this response is largely ESR-independent. Taken together, these results suggest that a branch point exists in the current model for DNA damage-signaled transcription in S. cerevisiae.

Intrinsic mitochondrial dysfunction in ATM-deficient lymphoblastoid cells.

One of the characteristic features of cells from patients with ataxia telangiectasia (A-T) is that they are in a state of continuous oxidative stress and exhibit constitutive activation of pathways that normally respond to oxidative damage. In this report, we investigated whether the oxidative stress phenotype of A-T cells might be a reflection of an intrinsic mitochondrial dysfunction. Mitotracker Red staining showed that the structural organization of mitochondria in A-T cells was abnormal compared to wild-type. Moreover, A-T cells harbored a much larger population of mitochondria with decreased membrane potential (DeltaPsi) than control cells. In addition, the basal expression levels of several nuclear DNA-encoded oxidative damage responsive genes whose proteins are targeted to the mitochondria--polymerase gamma, mitochondrial topoisomerase I, peroxiredoxin 3 and manganese superoxide dismutase--are elevated in A-T cells. Consistent with these results, we found that overall mitochondrial respiratory activity was diminished in A-T compared to wild-type cells. Treating A-T cells with the antioxidant, alpha lipoic acid (ALA), restored mitochondrial respiration rates to levels approaching those of wild-type. When wild-type cells were transfected with ATM-targeted siRNA, we observed a small but significant reduction in the respiration rates of mitochondria. Moreover, mitochondria in A-T cells induced to stably express full-length ATM, exhibited respiration rates approaching those of wild-type cells. Taken together, our results provide evidence for an intrinsic mitochondrial dysfunction in A-T cells, and implicate a requirement for ATM in the regulation of mitochondrial function.

Transfusion and bleeding in coronary artery bypass grafting: an on-pump versus off-pump comparison.

Blood transfusion rates in coronary artery bypass grafting (CABG) surgery using cardiopulmonary bypass (CPB) are typically higher compared with off-pump CABG (OPCAB). However, few studies have specifically examined intraoperative hemodilution as a contributing factor. The aim of this retrospective review was to compare the effect of using CPB or OPCAB on red blood cell (RBC) transfusion and postoperative bleeding. The lowest intraoperative hematocrit (Hct) was used as marker of intraoperative hemodilution. We reviewed the perioperative data of all isolated CABG patients at a metropolitan hospital from January 2003 to June 2005. Stepwise regression analyses were performed to determine whether CPB was an independent predictor of RBC transfusion, reoperation for bleeding, or postoperative chest drainage. Of a total of 1043 patients, there were 433 CPB and 610 off-pump cases. CPB use was not significantly related to increased RBC transfusions (odds ratio [OR], 0.98; 95% confidence interval [CI], 0.63-1.52; p = .921) and was associated with a lower incidence of reoperations for bleeding (OR, 0.4; 95% CI, 0.2-0.8; p = .009). There was less chest drainage over the first 12 hours in patients undergoing CPB (p < .0001); however, total postoperative chest drainage was not significantly related to operative procedure (p = .122). The lowest documented intraoperative Hct was a significant factor in RBC transfusions (OR, 0.89; p < .0001), an increased reoperation rate for bleeding (OR, 0.9; p = .001) and more postoperative chest drainage (log10-transformed: at 12 hours, b = -0.009, p < .0001; total, b = -0.006, p < .0001). CPB is not an independent risk factor in the incidence of RBC transfusions and is not associated with increased postoperative bleeding for isolated CABG. However, intraoperative hemodilution is an independent risk factor, with a lower intraoperative Hct associated with more RBC transfusions, increased reoperations for bleeding, and increased postoperative chest drainage. Addressing intraoperative hemodilution is important in minimizing CPB-associated morbidities.

The adaptive imbalance in base excision-repair enzymes generates microsatellite instability in chronic inflammation.

Chronic infection and associated inflammation are key contributors to human carcinogenesis. Ulcerative colitis (UC) is an oxyradical overload disease and is characterized by free radical stress and colon cancer proneness. Here we examined tissues from noncancerous colons of ulcerative colitis patients to determine (a) the activity of two base excision-repair enzymes, AAG, the major 3-methyladenine DNA glycosylase, and APE1, the major apurinic site endonuclease; and (b) the prevalence of microsatellite instability (MSI). AAG and APE1 were significantly increased in UC colon epithelium undergoing elevated inflammation and MSI was positively correlated with their imbalanced enzymatic activities. These latter results were supported by mechanistic studies using yeast and human cell models in which overexpression of AAG and/or APE1 was associated with frameshift mutations and MSI. Our results are consistent with the hypothesis that the adaptive and imbalanced increase in AAG and APE1 is a novel mechanism contributing to MSI in patients with UC and may extend to chronic inflammatory or other diseases with MSI of unknown etiology.