Ethical considerations in the collection of genetic data from critically ill patients: what do published studies reveal about potential directions for empirical ethics research?

Critical illness trials involving genetic data collection are increasingly commonplace and pose challenges not encountered in less acute settings, related in part to the precipitous, severe and incapacitating nature of the diseases involved. We performed a systematic literature review to understand the nature of such studies conducted to date, and to consider, from an ethical perspective, potential barriers to future investigations. We identified 79 trials enrolling 24 499 subjects. Median (interquartile range) number of participants per study was 263 (116.75-430.75). Of these individuals, 16 269 (66.4%) were Caucasian, 1327 (5.4%) were African American, 1707 (7.0%) were Asian Pacific Islanders and 139 (0.6%) were Latino. For 5020 participants (20.5%), ethnicity was not reported. Forty-eight studies (60.8%) recruited subjects from single centers and all studies examined a relatively small number of genetic markers. Technological advances have rendered it feasible to conduct clinical studies using high-density genome-wide scanning. It will be necessary for future critical illness trials using these approaches to be of greater scope and complexity than those so far reported. Empirical research into issues related to greater ethnic inclusivity, accuracy of substituted judgment and specimen stewardship may be essential for enabling the conduct of such trials.

Single and binary ion sorption equilibria of monovalent and divalent ions in commercial ion exchange membranes.

The co-ion and counter-ion sorption of monovalent (Na+, K+, Cl- and NO3-) and divalent ions (Ca2+ and SO42-) in commercial Neosepta ion exchange membranes were systemically studied in both single and binary salt systems. The new generation of Neosepta cation exchange membrane (CSE) showed a significant difference in water uptake and co-ion sorption compared to the earlier generation (CMX). Use of the Manning model confirmed that there were significant differences between these membranes, with the estimated value of the Manning parameter changing from 1.0 ± 0.1 for CMX to 2.8 ± 0.5 for CSE. There were fewer differences between the two Neosepta anion exchange membranes, AMX and ASE. In single salt solutions, potassium sorbed most strongly into the cation exchange membranes, but in binary salt mixtures, calcium dominated due to Donnan exclusion at low concentrations. While these trends were expected, the sorption behaviour in the anion exchange membranes was more complex. The water uptake of both AMX and ASE was shown to be the greatest in Na2SO4 solutions. This strong water uptake was reflected in strong sorption of sulphate ions in a single salt solution. Conversely, in a binary salt mixture with NaCl, sulphate sorption fell significantly at higher concentrations. This was possibly caused by ion pairing within the solution, as well as the strongly hydrophobic nature of styrene in the charged polymer. Water uptake was lowest in NaNO3 solutions, even though sorption of the nitrate ion was comparable to that of chloride in these single salt solutions. In the binary mixture, nitrate was absorbed more strongly than chloride. These results could be due to the low surface charge density of this ion allowing it to bond more strongly with the hydrophobic polymeric backbone at the exclusion of water and other ions.

Tyrphostin AG 556 improves survival and reduces multiorgan failure in canine Escherichia coli peritonitis.

Tyrosine kinase-dependent cell signaling is postulated to be a pivotal control point in inflammatory responses initiated by bacterial products and TNF. Using a canine model of gram-negative septic shock, we investigated the effect of tyrosine kinase inhibitors (tyrphostins) on survival. Animals were infected intraperitoneally with Escherichia coli 0111: B4, and then, in a randomized, blinded fashion, were treated immediately with one of two tyrphostins, AG 556 (n = 40) or AG 126 (n = 10), or with control (n = 50), and followed for 28 d or until death. All animals received supplemental oxygen, fluids, and antibiotics. Tyrphostin AG 556 improved survival times when compared to controls (P = 0.05). During the first 48 h after infection, AG 556 also improved mean arterial pressure, left ventricular ejection fraction, cardiac output, oxygen delivery, and alveolar-arterial oxygen gradient compared to controls (all P < or = 0.05). These improvements in organ injury were significantly predictive of survival. Treatment with AG 556 had no effect on clearance of endotoxin or bacteria from the blood (both P = NS); however, AG 556 did significantly lower serum TNF levels (P = 0.03). These data are consistent with the conclusion that AG 556 prevented cytokine-induced multiorgan failure and death during septic shock by inhibiting cell-signaling pathways without impairing host defenses as determined by clearance of bacteria and endotoxin.

Molecular simulation and experimental study of substituted polyacetylenes: fractional free volume, cavity size distributions and diffusion coefficients.

Glassy, disubstituted acetylene-based polymers exhibit extremely high gas permeabilities and high vapor/gas selectivities, which is quite unusual for conventional glassy polymers such as polysulfone. Diffusion coefficients of poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] (PTMSDPA) and poly[diphenylacetylene] (PDPA) were obtained using both molecular simulation and experimental techniques. PTMSDPA, a disubstituted glassy acetylene-based polymer, exhibits higher diffusivity than its desilylated analogue, PDPA. Simulation results are in good agreement with experimental data. Cavity size (free volume) distributions of both polymers are also obtained using an energetic-based algorithm (in't Veld et al., J. Phys. Chem. B 2000, 104, 12028) developed recently. Larger cavities in PTMSDPA contribute to its higher diffusivity, and higher permeability.

Anti-inflammatory therapies in sepsis and septic shock.

Despite advances in supportive care, the morbidity and mortality rate resulting from sepsis and septic shock remain high (30 - 50%). A central hypothesis driving sepsis research in recent years is that this syndrome is the result of excessive inflammation. Therapies designed to inhibit the inflammatory response were first shown to be markedly beneficial in animal models of sepsis and then tested in numerous clinical trials involving thousands of patients. Three broad anti-inflammatory strategies have been investigated. First, glucocorticoids in high doses administered at the onset of sepsis were studied. This approach proved unsuccessful. More recently, however, glucocorticoids in lower doses have been found to have a beneficial effect in patients with septic shock. Whether the mechanism of this treatment benefit is through inhibition of inflammation, or by counteracting a relative steroid refractoriness occurring during sepsis, remains unknown. The next focus of research were agents active against the endotoxin molecule. However, as with the experience with glucocorticoids, this approach lacked a consistent pattern of efficacy. It is unclear if this lack of efficacy is the result of endotoxin being a poor therapeutic target, or from testing agents which lacked the appropriate biological activity. Most recently, clinical trials in sepsis have focused on inhibiting specific host pro-inflammatory mediators (e.g., TNF, interleukins). While individual trials of inhibitors of these pro-inflammatory mediators failed to show a convincing benefit, pooling the results of these trials suggest that this approach has a marginal effect, supporting a role for excessive inflammation in sepsis. An unanswered question is reconcilling the very favourable effects obtained with anti-inflammatory treatments in animal models with the marginal results in humans. Further clinical and laboratory research is needed and may provide insight into more effective ways to use the anti-inflammatory agents already tested, or to investigate other potentially more effective anti-inflammatory agents in this syndrome.

A meta-analysis of prospective trials comparing percutaneous and surgical tracheostomy in critically ill patients.

STUDY OBJECTIVES: Tracheostomy is one of the most commonly performed procedures in the patient receiving long-term mechanical ventilation. While percutaneous dilational tracheostomy (PDT) is becoming increasingly utilized as an alternative to conventional surgical tracheostomy, most literature evaluating these two techniques is neither prospective nor controlled. We performed a meta-analysis of available prospective controlled studies comparing PDT and surgical tracheostomy in critically ill patients to more fully understand the relative benefits and risks of these two procedures in this population. DESIGN: Meta-analysis using Mantel-Haenszel fixed effect model. INTERVENTIONS: We performed searches of MEDLINE, Current Contents, Best Evidence, Cochrane, and HealthSTAR databases from 1985 to present to identify prospective controlled studies comparing PDT and surgical tracheostomy in critically ill patients. After establishing clinical and statistical homogeneity (Q: statistic), studies were analyzed by a Mantel-Haenszel fixed effect model. For each clinical end point examined, PDT and surgical tracheostomy were compared by calculating either absolute differences or odds ratios (ORs) with 95% confidence intervals (CIs) for continuous or discrete variables, respectively. MEASUREMENTS AND RESULTS: We pooled data from five studies (236 patients) satisfying our search criteria to analyze eight clinical end points. Operative time was shorter for PDT than surgical tracheostomy: absolute difference with 95% CI, 9. 84 min (7.83 to 10.85 min). There was no difference comparing PDT and surgical tracheostomy with respect to overall operative complication rates: OR with 95% CI, 0.732 (0.05 to 9.37). However, relative to surgical tracheostomy, PDT was associated with less perioperative bleeding (OR with 95% CI, 0.14 [0.02 to 0.39]), a lower overall postoperative complication rate (OR with 95% CI, 0.14 [0.07 to 0.29]), as well as a lower postoperative incidence of bleeding (OR with 95% CI, 0.39 [0.17 to 0.88]), and stomal infection (OR with 95% CI, 0.02 [0.01 to 0.07]). No difference was identified in days intubated prior to tracheostomy (absolute difference with 95% CI, 0.16 days [- 0.9 to 1.22 days]), overall procedure-related complications (OR with 95% CI, 0.73 [0.06 to 9.37]), or death (OR with 95% CI, 0.63 [0.18 to 2.20]) comparing these two techniques. CONCLUSIONS: Despite its popularity, there are currently only a limited number of small studies prospectively evaluating PDT and surgical tracheostomy. Our meta-analysis of these studies suggests potential advantages of PDT relative to surgical tracheostomy, including ease of performance, and lower incidence of peristomal bleeding and postoperative infection. If confirmed by additional, adequately powered prospective trials, these findings support PDT as the procedure of choice for the establishment of elective tracheostomy in the appropriately selected critically ill patient.

Interleukin-1 receptor antagonist as therapy for inflammatory disorders.

IL-1 is a pivotal mediator of the immune response and has been implicated in inflammatory and infectious diseases. As a consequence, the administration of IL-1 receptor antagonist (IL-1ra), a recombinantly synthesised endogenous inhibitor of IL-1, has appeal as a therapeutic strategy in these conditions. To date, the largest clinical experiences with IL-1ra have been in the setting of sepsis and rheumatoid arthritis (RA). Like other anti-inflammatory agents that target a specific mediator, IL-1ra was found to lack efficacy when given in conjunction with standard therapy in patients with sepsis and septic shock. In contrast, recent studies enrolling patients with RA suggest that IL-1ra significantly ameliorates disease activity and retards joint destruction. Whether the respective lack of efficacy and success of IL-1ra in these two diseases is a result of differences in the pathologic processes involved, or reflects the nature in which the clinical studies were conducted, is unclear. Further, the effectiveness of IL-1ra compared to other anticytokine and conventional treatments in RA remains to be clarified. Nonetheless, the recent finding that IL-1ra has the ability to favourably influence a chronic inflammatory disease supports the hypothesis that inhibition of a single mediator of the immune response may have clinical impact.

Cytochrome P450 polymorphisms are associated with reduced warfarin dose.

BACKGROUND: Warfarin use is complicated by an erratic dose response. Interpatient variability associated with warfarin therapy may be partly attributable to polymorphisms of the cytochrome P450 (CYP) complex. The purpose of this study was to ascertain the frequency and influence of CYP polymorphisms on warfarin dosing in our patient population. METHODS: Patients receiving warfarin therapy were recruited from the inpatient divisions of our hospital. Genotyping for known polymorphic alleles of the CYP subfamilies CYP2C9 (CYP2C9*1, CYP2C9*2, and CYP2C9*3) and CYP2A6 (CYP2A6*1, CYP2A6*2) with the use of standard methods of polymerase chain reaction amplification was performed. An unpaired t test was used to statistically compare genotypes. RESULTS: Genotype frequency in 38 patients is as follows: CYP2C9*1/CYP2C9*1, 71%; CYP2C9*1/CYP2C9*2, 21%; CYP2C9*2/CYP2C9*2, 3%; CYP2C9*1/CYP2C9*3, 5%; CYP2A6*1/CYP2A6*1, 95%; CYP2A6*1/CYP2A6*2, 5%. Compared to a wild-type genotype, the presence of the CYP2C9*2, CYP2C9*3, or CYP2A6*2 allele was associated with a significant reduction in weekly warfarin dose (mean weekly warfarin dose [+/- SE] for wild-type genotype was 0.397 +/- 0.024 mg/kg/wk vs 0.307 +/- 0.03 mg/kg/wk for carriers of CYP2C9*2, CYP2C9*3, or CYP2A6*2 polymorphism; P =.03). CONCLUSIONS: Polymorphisms that impair warfarin metabolism are common, occurring in 34% of patients, and are associated with increased warfarin sensitivity. The use of genotypic information to prescribe more accurate doses of warfarin may increase the safety and efficacy of this medication.

Controlled trials of rG-CSF and CD11b-directed MAb during hyperoxia and E. coli pneumonia in rats.

We studied the effects of inhibiting and augmenting neutrophil function by using an immunocompetent rat model of infectious and hyperoxic lung injury. After intrabronchial Escherichia coli challenge at all fractional inspired O2 (FIO2) values studied (FIO2 = 0.21, 0.60, and 0.95) and after lethal O2 exposure alone (FIO2 = 0.90), lung injury, as measured by histological and physiological changes, was reduced by a CD11b/CD18-directed monoclonal antibody (MAb 1B6, P < 0.05 vs. controls) but was increased by recombinant granulocyte colony-stimulating factor (rG-CSF; P < 0.05 vs. control; MAb 1B6 vs. rG-CSF, P < 0.004). Pulmonary neutrophil counts were reduced by MAb 1B6 (P < 0.04) and increased by rG-CSF (P < 0.0004) compared with control animals. However, despite antibiotics, MAb 1B6 and rG-CSF both significantly increased the relative risk of death, independent of O2 concentration, during E. coli pneumonia (1.74 [symbol: see text] 1.20 and 2.39 [symbol: see text] 1.19, respectively, each P < 0.01). During lethal hyperoxia, MAb 1B6 increased the relative risk of death (1.76 [symbol: see text] 1.28, P < 0.16), whereas rG-CSF had no effect on survival (0.97 [symbol: see text] 1.28, P = 0.89). Thus inhibition of neutrophil function attenuated and enhancement worsened lung injury in response to infectious and hyperoxic challenges, supporting a pathophysiological role of the neutrophil in these processes. However, it is problematic that MAb 1B6 therapy, despite preventing lung damage, ultimately worsened host defenses and survival. Furthermore, rG-CSF also adversely affected survival during infectious lung injury, demonstrating the inherent risks of inhibiting or augmenting neutrophil function in an immunocompetent host during infection.

rG-CSF reduces endotoxemia and improves survival during E. coli pneumonia.

We investigated the effects of recombinant granulocyte colony-stimulating factor (rG-CSF) during canine bacterial pneumonia. Beagles with chronic tracheostomies received daily subcutaneous rG-CSF (5 micrograms/kg body wt) or placebo for 14 days, beginning 9 days before intrabronchial inoculation with E. coli. Animals received antibiotics and fluid support; a subset received humidified oxygen (fractional inspired O2 0.40). Compared with controls, rG-CSF increased circulating neutrophil counts (57.4 vs. 11.0 x 10(3)/mm3, day 1 after infection; P = 0.0001), decreased plasma endotoxin (7.5 vs. 1.1 EU/ml at 8 h; P < 0.01) and serum tumor necrosis factor-alpha (3,402 vs. 729 pg/ml at 2 h; P = 0.01) levels, and prolonged survival (relative risk of death = 0.45, 95% confidence interval 0.21-0.97; P = 0.038). Also, rG-CSF attenuated sepsis-associated myocardial dysfunction (P < 0.001). rG-CSF had no effect on pulmonary function or on blood and lung bacteria counts (all P = not significant). Other animals challenged with endotoxin (4 mg/kg i.v.) after similar treatment with rG-CSF had lower serum endotoxin levels (7.62 vs. 5.81 log EU/ml at 6 h; P < 0.01) and less cardiovascular dysfunction (P < 0.05 to < 0.002) but similar tumor necrosis factor-alpha levels (P = not significant) compared with controls. Thus prophylactic rG-CSF sufficient to increase circulating neutrophils during bacterial pneumonia may improve cardiovascular function and survival by mechanisms that in part enhance the clearance of bacterial toxins but do not improve lung function.

Continuous arteriovenous hemofiltration does not improve survival in a canine model of septic shock.

BACKGROUND: We examined whether or not continuous arteriovenous hemofiltration (CAVH), in the absence of renal failure, would improve either hemodynamic abnormalities or survival in a canine model of septic shock. STUDY DESIGN: Escherichia coli 0111, as an intraperitoneal clot, was surgically implanted into 21 one- to two-year-old purpose-bred beagles. The dogs were randomized to no CAVH (control group, n = 7), sham CAVH (extracorporeal circulation without hemofiltration, n = 7), or true CAVH (hemofiltration with removal of 600 mL/hour of ultrafiltrate, n = 7). Hemofiltration began one hour after clot implantation and continued for six hours. All dogs received antibiotics and had serial hemodynamic and laboratory evaluations. RESULTS: During the first seven hours of the study, all dogs displayed a progressive, significant decrease in mean arterial pressure, cardiac index, left ventricular ejection fraction, and serum pH (all p < 0.05). Two of seven dogs in the control group, one of seven dogs in the sham CAVH group, and one of seven dogs in the true CAVH group survived seven days after clot implantation. True CAVH, which included fluid replacement with lactated Ringer's solution, significantly increased serum lactate and decreased serum bicarbonate levels after six hours (both p < 0.05). However, pH did not differ between the three treatment groups (p > 0.20). Continuous arteriovenous hemofiltration therapy had no significant effect on cardiovascular abnormalities or survival. CONCLUSIONS: The results of this study suggest that CAVH would be unlikely to provide benefit to patients with gram-negative septic shock, in the absence of renal failure.

Extreme warfarin sensitivity in siblings associated with multiple cytochrome P450 polymorphisms.

Warfarin use is complicated by an erratic dose response. Warfarin is metabolized by two distinct subfamilies of the cytochrome P450 (CYP) complex. We describe two siblings with extreme sensitivity to warfarin who share an unusual CYP genotype. These individuals illustrate both the importance of genetics in influencing the metabolism of warfarin as well as the potential utility of genetic testing as a guide to prescribing this medication.

Ultrapermeable, reverse-selective nanocomposite membranes.

Polymer nanocomposites continue to receive tremendous attention for application in areas such as microelectronics, organic batteries, optics, and catalysis. We have discovered that physical dispersion of nonporous, nanoscale, fumed silica particles in glassy amorphous poly(4-methyl-2-pentyne) simultaneously and surprisingly enhances both membrane permeability and selectivity for large organic molecules over small permanent gases. These highly unusual property enhancements, in contrast to results obtained in conventional filled polymer systems, reflect fumed silica-induced disruption of polymer chain packing and an accompanying subtle increase in the size of free volume elements through which molecular transport occurs, as discerned by positron annihilation lifetime spectroscopy. Such nanoscale hybridization represents an innovative means to tune the separation properties of glassy polymeric media through systematic manipulation of molecular packing.

Apoptotic cell death in patients with sepsis, shock, and multiple organ dysfunction.

OBJECTIVES: The purpose of this study was to determine whether apoptosis is a major mechanism of cell death in patients with sepsis. The activities of caspase-3 and the antiapoptotic protein, BCL-2, were investigated also. DESIGN: A prospective study of 20 patients who died of sepsis and multiple organ dysfunction was performed. The control group of 16 patients consisted of critically ill, nonseptic patients who were evaluated either prospectively (7) or retrospectively (9). In addition, normal colon sections from seven patients who had bowel resections were included. Apoptosis was evaluated in hematoxylin and eosin-stained specimens by deoxyuridine triphosphate nick end-labeling (TUNEL) and by DNA gel electrophoresis. SETTING: Two academic medical centers. PATIENTS: Critically ill patients. MEASUREMENTS AND MAIN RESULTS: In septic patients, apoptosis was detected in diverse organs by all three methods with a predominance in lymphocytes and intestinal epithelial cells. Hematoxylin and eosin-stained specimens from septic patients demonstrated at least focal apoptosis in 56.3% of spleens, 47.1% of colons, and 27.7% of ileums. Indirect evidence of lymphocyte apoptosis in septic patients included extensive depletion of lymphocytes in white pulp and a marked lymphocytopenia in 15 of 19 patients. Hematoxylin and eosin from nonseptic patients' tissues revealed a low level of apoptosis in one patient only. The TUNEL method increased in positivity with a delay in tissue fixation and was highly positive in many tissues from both septic and nonseptic patients. Immunohistochemical staining for active caspase-3 showed a marked increase in septic vs. nonseptic patients (p < .01), with >25% to 50% of cells being positive focally in the splenic white pulp of six septic but in no nonseptic patients. CONCLUSIONS: We conclude that caspase-3-mediated apoptosis causes extensive lymphocyte apoptosis in sepsis and may contribute to the impaired immune response that characterizes the disorder.