Oncogenes expand during evolution to withstand somatic amplification.

Background: Cancer-related genes are under intense evolutionary pressure. We conjectured that gene size is an important determinant of amplification propensity for oncogenes and thus cancer susceptibility and therefore could be subject to natural selection. Patients and methods: Gene information, including size and genomic locations, of all protein-coding genes were downloaded from Ensembl (release 87). Quantification of gene amplification was based on Genomic Identification of Significant Targets in Cancer scores obtained from available The Cancer Genome Atlas studies. Results: Oncogenes are larger in size as compared with non-cancer genes (mean size: 92.1 kb versus 61.4 kb; P < 0.0001) in the human genome, which is contributed by both increased total exon size (mean size: 4.6 kb versus 3.4 kb; P < 0.0001) and higher intronic content (mean %: 84.8 versus 78.0; P < 0.01). Such non-random size distribution and intronic composition are conserved in mouse and Drosophila (all P < 0.0001). Stratification by gene age indicated that young oncogenes have been subject to a stronger evolutionary pressure for gene expansion than their non-cancer counterparts. Pan-cancer analysis demonstrated that larger oncogenes were amplified to a lesser extent. Tumor-suppressor genes also moved toward small oncogenes in the course of evolution. Conclusions: Oncogenes expand in size whereas tumor-suppressor genes move closer to small oncogenes in the course of evolution to withstand oncogenic somatic amplification. Our findings have shed new light on the previously unappreciated influence of gene size on oncogene amplification and elucidated how cancers have shaped our genome to its present configuration.

A systematic review and consensus definitions for standardised end-points in perioperative medicine: pulmonary complications.

BACKGROUND: There is a need for robust, clearly defined, patient-relevant outcome measures for use in randomised trials in perioperative medicine. Our objective was to establish standard outcome measures for postoperative pulmonary complications research. METHODS: A systematic literature search was conducted using MEDLINE, Web of Science, SciELO, and the Korean Journal Database. Definitions were extracted from included manuscripts. We then conducted a three-stage Delphi consensus process to select the optimal outcome measures in terms of methodological quality and overall suitability for perioperative trials. RESULTS: From 2358 records, the full texts of 81 manuscripts were retrieved, of which 45 met the inclusion criteria. We identified three main categories of outcome measure specific to perioperative pulmonary outcomes: (i) composite outcome measures of multiple pulmonary outcomes (27 definitions); (ii) pneumonia (12 definitions); and (iii) respiratory failure (six definitions). These were rated by the group according to suitability for routine use. The majority of definitions were given a low score, and many were imprecise, difficult to apply consistently, or both, in large patient populations. A small number of highly rated definitions were identified as appropriate for widespread use. The group then recommended four outcome measures for future use, including one new definition. CONCLUSIONS: A large number of postoperative pulmonary outcome measures have been used, but most are poorly defined. Our four recommended outcome measures include a new definition of postoperative pulmonary complications, incorporating an assessment of severity. These definitions will meet the needs of most clinical effectiveness trials of treatments to improve postoperative pulmonary outcomes.

Risk prediction models for delirium in the intensive care unit after cardiac surgery: a systematic review and independent external validation.

Numerous risk prediction models are available for predicting delirium after cardiac surgery, but few have been directly compared with one another or been validated in an independent data set. We conducted a systematic review to identify validated risk prediction models of delirium (using the Confusion Assessment Method-Intensive Care Unit tool) after cardiac surgery and assessed the transportability of the risk prediction models on a prospective cohort of 600 consecutive patients undergoing cardiac surgery at a university hospital in Hong Kong from July 2013 to July 2015. The discrimination (c-statistic), calibration (GiViTI calibration belt), and clinical usefulness (decision curve analysis) of the risk prediction models were examined in a stepwise manner. Three published high-quality intensive care unit delirium risk prediction models (n=5939) were identified: Katznelson, the original PRE-DELIRIC, and the international recalibrated PRE-DELIRIC model. Delirium occurred in 83 patients (13.8%, 95% CI: 11.2-16.9%). After updating the intercept and regression coefficients in the Katznelson model, there was fair discrimination (0.62, 95% CI: 0.58-0.66) and good calibration. As the original PRE-DELIRIC model was already validated externally and recalibrated in six countries, we performed a logistic calibration on the recalibrated model and found acceptable discrimination (0.75, 95% CI: 0.72-0.79) and good calibration. Decision curve analysis demonstrated that the recalibrated PRE-DELIRIC risk model was marginally more clinically useful than the Katznelson model. Current models predict delirium risk in the intensive care unit after cardiac surgery with only fair to moderate accuracy and are insufficient for routine clinical use.

Early Magnesium Treatment After Aneurysmal Subarachnoid Hemorrhage: Individual Patient Data Meta-Analysis.

BACKGROUND AND PURPOSE: Delayed cerebral ischemia (DCI) is an important cause of poor outcome after aneurysmal subarachnoid hemorrhage (SAH). Trials of magnesium treatment starting <4 days after symptom onset found no effect on poor outcome or DCI in SAH. Earlier installment of treatment might be more effective, but individual trials had not enough power for such a subanalysis. We performed an individual patient data meta-analysis to study whether magnesium is effective when given within different time frames within 24 hours after the SAH. METHODS: Patients were divided into categories according to the delay between symptom onset and start of the study medication: <6, 6 to 12, 12 to 24, and >24 hours. We calculated adjusted risk ratios with corresponding 95% confidence intervals for magnesium versus placebo treatment for poor outcome and DCI. RESULTS: We included 5 trials totaling 1981 patients; 83 patients started treatment<6 hours. For poor outcome, the adjusted risk ratios of magnesium treatment for start <6 hours were 1.44 (95% confidence interval, 0.83-2.51); for 6 to 12 hours 1.03 (0.65-1.63), for 12 to 24 hours 0.84 (0.65-1.09), and for >24 hours 1.06 (0.87-1.31), and for DCI, <6 hours 1.76 (0.68-4.58), for 6 to 12 hours 2.09 (0.99-4.39), for 12 to 24 hours 0.80 (0.56-1.16), and for >24 hours 1.08 (0.88-1.32). CONCLUSIONS: This meta-analysis suggests no beneficial effect of magnesium treatment on poor outcome or DCI when started early after SAH onset. Although the number of patients was small and a beneficial effect cannot be definitively excluded, we found no justification for a new trial with early magnesium treatment after SAH.

The analgesic efficacy of continuous wound instillation with ropivacaine after open hepatic surgery.

The analgesic efficacy of continuous local anaesthetic wound instillation after open hepatic surgery was evaluated. Forty-eight patients scheduled for elective liver surgery were assigned to receive either ropivacaine 0.25% or saline infusion at 4 ml.h(-1) for 68 h via two multi-orifice indwelling catheters placed within the musculo-fascial layer before skin closure; plasma ropivacaine concentrations were measured during the infusion. Supplemental analgesia was provided by intravenous patient-controlled analgesia morphine. Patients in the ropivacaine group had decreased mean (SD) total morphine consumption (58 (30) mg vs 86 (44) mg, p = 0.01) and less pain at rest as well as after spirometry at 4, 12, 24, 48 and 72 h postoperatively (p < 0.01). Forced vital capacity was reduced postoperatively in both groups, but the reduction was greater in the saline group at 12 and 24 h (p = 0.03). The mean plasma concentration of ropivacaine increased to 2.05 (0.78) µg.ml(-1) at the point when the infusion was terminated.

Impact of an auditory stimulus on baseline cortisol concentrations in clinically normal dogs.

Baseline cortisol concentrations are routinely used to screen dogs for hypoadrenocorticism (HOC); this diagnosis must then be confirmed with an ACTH stimulation test. A baseline cortisol concentration less than 55 nmol/L (2 µg/dL) is highly sensitive for HOC but lacks specificity, with a false positive rate >20%. Many dogs with nonadrenal disease are therefore subjected to unnecessary additional testing. It was hypothesized that exposure to an unpleasant auditory stimulus before sample collection would improve the specificity of baseline cortisol measurements in dogs with nonadrenal disease by triggering cortisol production. Twenty-eight healthy client-owned dogs were included in the study, with a median age of 4 yr (range 2-9 yr) and a median weight of 20 kg (range 10-27 kg). Dogs were ineligible for inclusion if they had received short- or long-acting glucocorticoids within the previous 30 and 90 d, respectively. Dogs were randomly assigned to group 1 (control; no noise; n = 7), group 2 (brief noise: n = 10), or group 3 (long noise: n = 11). Each dog and owner were directed to a secluded area for approximately 15 min. Group 1 sat in relative quiet, exposed only to the background sounds of a veterinary hospital. Group 2 were exposed to the sound of a wet-dry vacuum in an adjacent hallway during the first 3 min of this period. Group 3 were exposed to random bursts of wet-dry vacuum noise during this period. At the end of the test interval, each dog was escorted to an adjacent examination room for blood collection. Samples were processed within 15 min; serum was frozen at -80°C before measurement of cortisol concentrations. Median serum cortisol concentrations and the proportion of dogs with results <55 nmol/L were similar for the 3 groups. The study hypothesis that exposure to the noise of a wet-dry vacuum cleaner would consistently drive baseline serum cortisol concentrations above 55 nmol/L in dogs with apparently normal adrenal function was therefore rejected.

The hepatitis C virus minigenome: a new cellular model for studying viral replication.

The cellular models used usually to study hepatitis C virus replication involve coupling between translation and replication. Because this linkage makes detailed analyses difficult a new cellular model was developed where replication is rendered independent of translation. The RNA replication was studied using RNA minigenomes where the reporter gene was flanked by the two untranslated regions of HCV. It was shown that these RNA minigenomes could be stably replicated into Huh7 cells expressing the HCV replication complex. This was obtained either by constitutively expressing the non-structural proteins into Huh7 hepatoma cells or by using Huh7 cells harboring replicons.

Identification of malignant cell clones in radio-induced murine thymic lymphomas by viral and cellular probes.

The role of B ecotropic recombinant retroviruses in the emergence and the progression of radio-induced thymic lymphomas was evaluated by analyzing the cell populations present in nine primary and in in vivo propagated tumors. For this, tumor DNAs were analyzed by the Southern method using probes specific for newly acquired proviral sequences, T-cell receptor beta-chain, and immunoglobulin heavy chain genes. Our results show that primary radio-induced tumors are composed of several tumoral cell clones but do not support that malignant cell transformation and proliferation are conferred, solely, by the newly acquired ecotropic recombinant retroviral sequences.

Characterization of monoclonal antibodies directed against the gp46 of human T-cell leukemia virus type I.

Essential HTLV-I biological functions depend on the structural motives of the surface glycoprotein (gp46). Monoclonal antibodies (mAbs) have been generated in order to identify functional regions of gp46. We obtained three monoclonal antibodies (3F3F10, 4F5F6 and 7G5D8) by immunizing Balb/c mice with beta-propiolactone inactivated HTLV-I producing cells and partially purified gp46. The mAbs are of the IgG 1 subclass. They have been characterized by western blot analysis, reactivity with HTLV-I and HTLV-II producing cells and ELISA binding assays using synthetic peptides. The immunoblot analysis performed with sheets prepared with the virus released by HUT 102 and 2060 cells (an HTLV-I virus producing cell line established in our laboratory) indicate that the three mAbs recognize a 46 kDa product as did the anti -gp46 mAb 0.5 alpha (18). Reactivity of the three mAbs with various cell lines was examined by indirect immunofluorescence assay. The mAb 7G5D8 stained strongly the membrane of all HTLV-I producing cells (MT2, C91/PL, HUT102 and cells of seven lines established in our laboratory and by A. Gessain); uninfected lymphoid cells (HSB-2, MOLT 4, CEM and PHA activated lymphocytes from normal donors) were negative. Interestingly cells of a HTLV-II producing line (344 MO) were positive. The mAbs 3F3F10 and 4F5F6 reacted with the same cells as did 7G5D8 but the fluorescence intensity was much lower than that observed with this later. A long synthetic peptide corresponding to the immunodominant region of the gp46 defined by the amino acids 175-199 and 10-mer peptides overlapping this region were used in an approach to identify the recognized epitope(s). The long 175-199 peptide was recognized by the three mAbs. 3F3F10 and 4F5F6 recognized none of the 10-mer peptides whereas 7G5D8 bound to 186-195 and 182-191 peptides. In addition 7G5D8 did not inhibit either syncytia formation or virus infection. In view of the data concerning the previously described mAbs 0.5 alpha, LAT 27 (5) and KE36-11 (6), our results suggest that the epitope recognized by 7G5D8 is different from those recognized by the former ones. As the 183-191 sequence corresponds to a region in which HTLV-I and HTLV-II harbour six common amino acids and two similar ones, this is consistent with the observation that 7G5D8 stained the HTLV-II producing cells 344 MO as well as all HTLV-I producing ones. Altogether our data support the hypothesis whereby this epitope recognized by 7G5D8 is contained within a sequence defined by amino acids 183-191.

Effect of ischemic preconditioning on brain tissue gases and pH during temporary cerebral artery occlusion.

Previous studies have demonstrated that a brief period of ischemia protect against subsequent severe ischemic insults to the brain, i.e. preconditioning. We evaluated the effects of ischemic preconditioning, produced by 2 min proximal temporary artery occlusion, on brain tissue gases and acidity during clipping of cerebral aneurysm. Twelve patients with aneurysmal subarachnoid hemorrhage were recruited. All patients received standard anesthetics. After craniotomy, a calibrated multiparameter catheter was inserted to measure oxygen (PtO2) tension, carbon dioxide (PtCO2) tension and pH (pHt) in tissue at risk of ischemia during temporary artery occlusion. In patients assigned to the preconditioning group, proximal artery was occluded initially for 2 min and was allowed to reperfuse for 30 min. All patients underwent cerebral artery occlusion for clipping of aneurysm. The rate of change in PtO2, PtCO2 and pHt after artery occlusion were compared between groups using unpaired t test. Baseline brain tissue gases and pHt were similar between groups. Following artery occlusion, the decline in PtO2 and pHt were significantly slower in the preconditioning group compared with the routine care group. These results suggested that ischemic preconditioning attenuates tissue hypoxia during subsequent artery occlusion. Brief occlusion of the proximal artery may be a simple maneuver for brain protection during complex cerebrovascular surgery.

Magnesium sulfate for brain protection during temporary cerebral artery occlusion.

We evaluated the effects of magnesium sulfate on brain tissue oxygen (PtO2) tension, carbon dioxide (PtCO2) tension and pH (pHt) in patients undergoing temporary artery occlusion for clipping of cerebral aneurysm. We studied 18 patients with aneurysmal subarachnoid hemorrhage. All patients received standard anesthetics using target controlled infusion of propofol (3 microg/ml) and remifentanil (10 ng/ml). After craniotomy, a calibrated multiparameter sensor (Neurotrend, Diametrics Medical, Minneapolis, MN) was inserted to measure PtO2, PtCO2 and pHt in tissue at risk of ischemia during temporary artery occlusion. Patients were then randomly allocated to receive either intravenous saline or magnesium 20 mmol over 10 min followed by an infusion 4 mmol/h. Plasma magnesium concentration, brain tissue gases and pHt were determined at baseline, 30 min after study drug infusion and 4 min after temporary clipping. Data were analyzed by factorial ANOVA with repeated measures. Intergroup difference was compared with unpaired t test. P value < 0.05 was considered significant. Patient characteristics, baseline brain tissue gases and pHt did not differ between groups. Magnesium infusion increased PtO2 by 34%. Following temporary artery occlusion, PtO2 and pHt decreased and PtCO2 increased in both groups. However, tissue hypoxia was less severe and the rate of PtO2 decline was slower in the magnesium group. Our data suggested that magnesium enhances tissue oxygenation and attenuates hypoxia during temporary artery occlusion.

Monitoring of autoregulation using intracerebral microdialysis in patients with severe head injury.

We evaluated the performance of continuous intracerebral microdialysis to indicate the autoregulatory reserve in 36 severely head-injured patients. All patients received standard treatment with intracranial pressure (ICP) monitoring. A microdialysis probe was placed in the frontal cortex anterior to the ICP catheter. Perfusate was collected frequently and extracellular concentration of glutamate was measured online using enzymatic method. Autoregulatory index was calculated by comparing glutamate concentration with CPP using Pearson's correlation. A correlation coefficient (r) < 0.5 is considered as loss of autoregulation, whereas r values approach 0 indicate preserved autoregulation. The change of autoregulatory status over time was correlated with outcome at 6 months. Three patterns of autoregulatory profiles were identified. Patients with intact autoregulation had satisfactory outcome. Transient impairment of autoregulation may result in favorable outcome if patients responded to treatment. However, persistent loss of autoregulation was associated with poor outcome (P < 0.001). The correlation between extracellular glutamate concentration (by microdialysis) and CPP is a useful index of autoregulation in head-injured patients. It predicts clinical outcome and may be used to guide therapy.

Re-defining the ischemic threshold for jugular venous oxygen saturation--a microdialysis study in patients with severe head injury.

Neurological change is more likely to occur when jugular venous oxygen saturation (SjvO2) is less than 50%. However, the value indicating cellular damage has not been clearly defined. We determined the critical SjvO2 value below which intracerebral extracellular metabolic abnormalities occurred in 25 patients with severe head injury. All patients received standard treatment with normoventilation and maintenance of intracranial pressure < 20 mmHg. SjvO2 was measured from the dominant jugular bulb using a calibrated fibreoptic catheter. Intracerebral metabolic monitoring was performed by collecting perfusate from a microdialysis probe placed in the frontal lobe anterior to the intracranial catheter. Excitotoxin (glutamate) and other extracellular metabolites (lactate, glucose and glycerol) were measured frequently using enzymatic and colorimetric methods. We observed biphasic relationships between SjvO2 and all intracerebral metabolites. Analysis of variance showed that there were rapid increases in glutamate, glycerol and lactate when SjvO2 dropped below 40, 43 and 45% respectively. Extracellular glucose decreased when SjvO2 dropped below 42%. Our findings suggested that the ischemic threshold for SjvO2 in patients with severe head injury is 45%, below which secondary brain damage occurred.

Intravenous magnesium sulfate to improve outcome after aneurysmal subarachnoid hemorrhage: interim report from a pilot study.

OBJECTIVES: Magnesium sulfate (MgSO4) may be useful in preventing neurological injury after subarachnoid haemorrhage (SAH). In this randomized, double-blind study we evaluated the safety and efficacy of MgSO4 infusion to improve clinical outcome after aneurysmal SAH. METHODS: With ethics committee approval and informed consents, 45 patients with SAH were randomly allocated to receive either MgSO4 80 mmol/day or saline infusion for 14 days. All patients also received intravenous nimodipine. Episodes of vasospasm were treated with hypertensive, hypervolemic therapy. Neurological status was assessed 3 months after haemorrhage using Barthel index and Glasgow outcome scale (GOS). Incidences of cardiac and pulmonary complications were also recorded. Data were compared between groups using Mann-Whitney or Fisher exact tests as appropriate. P < 0.05 was considered significant. RESULTS: Patient characteristics, severity of SAH and surgical treatment did not differ between groups. Although the number of episodes was not reduced, MgSO4 shortened the duration of vasospasm. Patients receiving MgSO4 tended to have fewer neurological deficits, better functional recovery and an improved score in GOS. However, none of these outcome variables reached statistical significance. The incidence of cardiac and pulmonary complications in the MgSO4 group (43%) was also similar to that in the saline group (59%), P = 0.14. CONCLUSIONS: MgSO4 infusion after aneurysmal SAH is well tolerated and may be useful in producing better outcome. A larger study is required to confirm the neuroprotective effect of MgSO4.

A prospective evaluation of health-related quality of life in Hong Kong Chinese patients with chronic non-cancer pain.

OBJECTIVE: To evaluate the health-related quality of life in Hong Kong Chinese patients with chronic non-cancer pain. DESIGN: Prospective cross-sectional survey. SETTING: Regional public hospitals, Hong Kong. PATIENTS: Patients attending out-patient pain management clinics between 1 July 2002 and 28 February 2003 were approached to complete a set of standardised questionnaires. MAIN OUTCOME MEASURES: Demographic profiles, treatment modality, litigation, compensation, social welfare status, Hospital Anxiety Depression Scale, and Medical Outcomes Survey short-form health survey (SF36). RESULTS: Data from 166 patients were analysed. The median numeric pain rating score was 6 (interquartile range, 2-10). Work-related injury occurred in 34.3% of patients, while another 34% were involved in pain-related litigation and 32% were receiving disability or unemployment benefit. Sixty-four percent of patients were managed by three or more disciplines, while 54.8% were also receiving complimentary alternative medical treatment, mainly traditional Chinese medicine (49.7%). The Hospital Anxiety Depression Score indicated clinical anxiety or depression in 71.1% of patients. All SF36 subscale scores were lower than the local population norm. Unemployed patients had higher depression scores (P = 0.005), while students or retirees had lower physical functioning scores (P = 0.004). Patients who were single had higher role emotion scores than those who were married or separated/widowed (P = 0.011). Logistic regression analysis showed that younger age (odds ratio = 0.95), being married (6.62), work-related injury (15.63) or higher general scores (1.03) were more likely to be associated with litigation. Social welfare benefit was associated with unemployment (3.39) and a lower level of physical functioning (0.98). CONCLUSION: There was a high prevalence of clinical anxiety, depression, and severe impairment in the health-related quality of life in Hong Kong Chinese patients with chronic non-cancer pain. Specific factors affected the health-related quality of life, likelihood of litigation, and social benefit.