Epidemiology and clinical relevance of persistent bacteraemia in patients with Gram-negative bloodstream infection: a retrospective cohort study.

OBJECTIVES: The risk factors and outcomes associated with persistent bacteraemia in Gram-negative bloodstream infection (GN-BSI) are not well described. We conducted a follow-on analysis of a retrospective population-wide cohort to characterize persistent bacteraemia in patients with GN-BSI. METHODS: We included all hospitalized patients >18 years old with GN-BSI between April 2017 and December 2021 in Ontario who received follow-up blood culture (FUBC) 2-5 days after the index positive blood culture. Persistent bacteraemia was defined as having a positive FUBC with the same Gram-negative organism as the index blood culture. We identified variables independently associated with persistent bacteraemia in a multivariable logistic regression model. We evaluated whether persistent bacteraemia was associated with increased odds of 30- and 90-day all-cause mortality using multivariable logistic regression models adjusted for potential confounders. RESULTS: In this study, 8807 patients were included; 600 (6.8%) had persistent bacteraemia. Having a permanent catheter, antimicrobial resistance, nosocomial infection, ICU admission, respiratory or skin and soft tissue source of infection, and infection by a non-fermenter or non-Enterobacterales/anaerobic organism were associated with increased odds of having persistent bacteraemia. The 30-day mortality was 17.2% versus 9.6% in those with and without persistent bacteraemia (aOR 1.65, 95% CI 1.29-2.11), while 90-day mortality was 25.5% versus 16.9%, respectively (aOR 1.53, 95% CI 1.24-1.89). Prevalence and odds of developing persistent bacteraemia varied widely depending on causative organism. CONCLUSIONS: Persistent bacteraemia is uncommon in GN-BSI but is associated with poorer outcomes. A validated risk stratification tool may be useful to identify patients with persistent bacteraemia.

Association between infectious diseases consultation and mortality in hospitalized patients with Gram-negative bloodstream infection: a retrospective population-wide cohort study.

OBJECTIVES: Data supporting routine infectious diseases (ID) consultation in Gram-negative bloodstream infection (GN-BSI) are limited. We evaluated the association between ID consultation and mortality in patients with GN-BSI in a retrospective population-wide cohort study in Ontario using linked health administrative databases. METHODS: Hospitalized adult patients with GN-BSI between April 2017 and December 2021 were included. The primary outcome was time to all-cause mortality censored at 30 days, analyzed using a mixed effects Cox proportional hazards model with hospital as a random effect. ID consultation 1-10 days after the first positive blood culture was treated as a time-varying exposure. RESULTS: Of 30,159 patients with GN-BSI across 53 hospitals, 11,013 (36.5%) received ID consultation. Median prevalence of ID consultation for patients with GN-BSI across hospitals was 35.0% with wide variability (range 2.7-76.1%, interquartile range 19.6-41.1%). 1041 (9.5%) patients who received ID consultation died within 30 days, compared to 1797 (9.4%) patients without ID consultation. In the fully-adjusted multivariable model, ID consultation was associated with mortality benefit (adjusted HR 0.82, 95% CI 0.77-0.88, p < 0.0001; translating to absolute risk reduction of -3.8% or NNT of 27). Exploratory subgroup analyses of the primary outcome showed that ID consultation could have greater benefit in patients with high-risk features (nosocomial infection, polymicrobial or non-Enterobacterales infection, antimicrobial resistance, or non-urinary tract source). CONCLUSIONS: Early ID consultation was associated with reduced mortality in patients with GN-BSI. If resources permit, routine ID consultation for this patient population should be considered to improve patient outcomes.

Follow-up blood cultures do not reduce mortality in hospitalized patients with Gram-negative bloodstream infection: a retrospective population-wide cohort study.

OBJECTIVES: The utility of follow-up blood cultures (FUBCs) in patients with Gram-negative bloodstream infection (GN-BSI) is controversial. Observational studies have suggested significant mortality benefit but may be limited by single-centre designs, immortal time bias, and residual confounding. We examined the impact of FUBCs on mortality in patients with GN-BSI in a retrospective population-wide cohort study in Ontario, Canada. METHODS: Adult patients with GN-BSI hospitalized between April 2017 and December 2021 were included. Primary outcome was all-cause mortality within 30 days. FUBC was treated as a time-varying exposure. Secondary outcomes were 90-day mortality, length of stay, and number of days alive and out of hospital at 30 and 90 days. RESULTS: Thirty-four thousand one hundred patients were included; 8807 (25.8%) patients received FUBC, of which 966 (11.0%) were positive. Median proportion of patients receiving FUBC was 18.8% (interquartile range, 10.0-29.7%; range, 0-66.1%) across 101 hospitals; this correlated with positivity and contamination rate. Eight hundred ninety (10.1%) patients in the FUBC group and 2263 (8.9%) patients in the no FUBC group died within 30 days. In the fully adjusted model, there was no association between FUBC and mortality (hazard ratio, 0.97; 95% CI, 0.90-1.04). Patients with FUBC had significantly longer length of stay (median, 11 vs. 7 days; adjusted risk ratio, 1.18; 95% CI, 1.16-1.21) and fewer number of days alive and out of hospital at 30 and 90 days. DISCUSSION: FUBC collection in patients with GN-BSI varies widely across hospitals and may be associated with prolonged hospitalization without clear survival benefit. Residual confounding may be present given the observational design. Clear benefit should be demonstrated in a randomized trial before widespread adoption of routine FUBC.

Validation of case-ascertainment algorithms using health administrative data to identify people who inject drugs in Ontario, Canada.

OBJECTIVES: Health administrative data can be used to improve the health of people who inject drugs by informing public health surveillance and program planning, monitoring, and evaluation. However, methodological gaps in the use of these data persist due to challenges in accurately identifying injection drug use (IDU) at the population level. In this study, we validated case-ascertainment algorithms for identifying people who inject drugs using health administrative data in Ontario, Canada. STUDY DESIGN AND SETTING: Data from cohorts of people with recent (past 12 months) IDU, including those participating in community-based research studies or seeking drug treatment, were linked to health administrative data in Ontario from 1992 to 2020. We assessed the validity of algorithms to identify IDU over varying look-back periods (ie, all years of data [1992 onwards] or within the past 1-5 years), including inpatient and outpatient physician billing claims for drug use, emergency department (ED) visits or hospitalizations for drug use or injection-related infections, and opioid agonist treatment (OAT). RESULTS: Algorithms were validated using data from 15,241 people with recent IDU (918 in community cohorts and 14,323 seeking drug treatment). An algorithm consisting of ≥1 physician visit, ED visit, or hospitalization for drug use, or OAT record could effectively identify IDU history (91.6% sensitivity and 94.2% specificity) and recent IDU (using 3-year look back: 80.4% sensitivity, 99% specificity) among community cohorts. Algorithms were generally more sensitive among people who inject drugs seeking drug treatment. CONCLUSION: Validated algorithms using health administrative data performed well in identifying people who inject drugs. Despite their high sensitivity and specificity, the positive predictive value of these algorithms will vary depending on the underlying prevalence of IDU in the population in which they are applied.

Predictors and disparities in neonatal and under 5 mortality in rural Pakistan: cross sectional analysis.

Background: Adopted in 2015, the sustainable development goals (SDGs) have set specific targets (SDG 3.2) for countries to reduce their neonatal mortality rate (NMR) to below 12 deaths per 1000 live births and under 5 mortality rate (U5MR) to below 25 deaths per 1000 live births by 2030. For Pakistan to achieve these targets, there is a need to measure these rates and understand the predictors of child mortality at sub-national level. Launched in 2016, the Umeed-e-Nau (UeN) or New Hope project is based on scaling up proven and effective Maternal and Newborn Child Health (MNCH) interventions in 8 of the highest burden districts of the country, using existing public sector platforms in Pakistan at both the community and facility level. The primary aim of the project is to reduce perinatal mortality in these districts by 20% from baseline. Methods: We report overall neonatal and post neonatal mortality rates for the two years preceding the UeN baseline household survey. Rates were calculated using the synthetic cohort probability method and predictors of neonatal and post neonatal mortality examined using Cox regression. To investigate spatial variations in the mortality rates, we calculated Moran's I at the district level using predicted probabilities of mortality. Finally, we create district level maps of predicted under 5 child mortality using a stochastic partial differentiation approach. Findings: A total of 26,258 children contributed to the analysis of mortality with 838 deaths in the neonatal period and 2236 under-5 deaths during the observation period from March 1, 2015 to March 17, 2017. Overall, we estimated the NMR to be 29.2 per 1000 live births (95% CI: 26.9-31.4) and the U5MR to be 86.1 per 1000 live births (95% CI: 85.5-86.8). We found evidence of within-district geospatial clustering of under 5 mortality (P < 0.0001) and that social factors (poverty, illiteracy, multiparity), poor coverage of community health workers and distance from health facilities were strongly associated with child mortality. Interpretation: Important factors associated with neonatal and post-neonatal mortality in our study population included maternal education, parity, household size and gender. Additionally, antenatal care coverage (at least 4 visits) was specifically associated with neonatal mortality only, whereas, LHW coverage and distance to health facility were strongly associated with post-neonatal mortality. These findings emphasise the need for comprehensive, multisectoral strategies to be implemented for future maternal and child health programs and outreach services in rural areas. Funding: The study was funded by an unrestricted grant from the Bill & Melinda Gates Foundation to the Aga Khan University (Grant OPP 1148892).

Antibiotic Selection and Duration for Catheter-Associated Urinary Tract Infection in Non-Hospitalized Older Adults: A Population-Based Cohort Study.

Background: We sought to evaluate the impact of antibiotic selection and duration of therapy on treatment failure in older adults with catheter-associated urinary tract infection (CA-UTI). Methods: We conducted a population-based cohort study comparing antibiotic treatment options and duration of therapy for non-hospitalized adults aged 66 and older with presumed CA-UTI (defined as an antibiotic prescription and an organism identified in urine culture in a patient with urinary catheterization documented within the prior 90 d). The primary outcome was treatment failure, a composite of repeat urinary antibiotic prescribing, positive blood culture with the same organism, all-cause hospitalization or mortality, within 60 days. We determined the risk of treatment failure accounting for age, sex, comorbidities, and healthcare exposure using log-binomial regression. Results: Of 4,436 CA-UTI patients, 2,709 (61.1%) experienced treatment failure. Compared to a reference of TMP-SMX (61.9% failure), of those treated with fluoroquinolones, 56.3% experienced failure (RR 0.91, 95% CI: 0.85-0.98) and 60.9% of patients treated with nitrofurantoin experienced failure (RR 1.02, 95% CI: 0.94-1.10). Compared to 5-7 days of therapy (treatment failure: 59.4%), 1-4 days was associated with 69.5% failure (RR 1.15, 95% CI: 1.05-1.27), and 8-14 days was associated with a 62.0% failure (RR 1.05, 95% CI: 0.99-1.11). Conclusions: Although most treatment options for CA-UTI have a similar risk of treatment failure, fluoroquinolones, and treatment durations ≥ 5 days in duration appear to be associated with modestly improved clinical outcomes. From a duration of therapy perspective, this study provides reassurance that relatively short courses of 5-7 days may be reasonable for CA-UTI.

Assessing transcriptomic reidentification risks using discriminative sequence models.

Gene expression data provide molecular insights into the functional impact of genetic variation, for example, through expression quantitative trait loci (eQTLs). With an improving understanding of the association between genotypes and gene expression comes a greater concern that gene expression profiles could be matched to genotype profiles of the same individuals in another data set, known as a linking attack. Prior works show such a risk could analyze only a fraction of eQTLs that is independent owing to restrictive model assumptions, leaving the full extent of this risk incompletely understood. To address this challenge, we introduce the discriminative sequence model (DSM), a novel probabilistic framework for predicting a sequence of genotypes based on gene expression data. By modeling the joint distribution over all known eQTLs in a genomic region, DSM improves the power of linking attacks with necessary calibration for linkage disequilibrium and redundant predictive signals. We show greater linking accuracy of DSM compared with existing approaches across a range of attack scenarios and data sets including up to 22,288 individuals, suggesting that DSM helps uncover a substantial additional risk overlooked by previous studies. Our work provides a unified framework for assessing the privacy risks of sharing diverse omics data sets beyond transcriptomics.

Evaluating the impact of a virtual outpatient care programme in preventing hospitalizations, emergency department visits and mortality for patients with COVID-19: a matched cohort study.

OBJECTIVES: To evaluate the impact of virtual care in preventing unnecessary healthcare visits for patients with SARS-CoV-2. METHODS: We conducted a retrospective matched cohort study, evaluating the COVID-19 Expansion to Outpatients (COVIDEO) programme involving virtual assessments for all positive patients in the Sunnybrook assessment centre from January 2020 to June 2021, followed by risk-stratified routine follow-up, couriering of oxygen saturation devices, and 24 hour/day direct-to-physician pager for urgent questions. We linked COVIDEO data to province-wide datasets, matching each eligible COVIDEO patient to ≤10 other Ontario SARS-CoV-2 patients on age, sex, neighbourhood, and date. The primary outcome was emergency department (ED) visit, hospitalization or death within 30 days. Multivariable regression accounted for comorbidities, vaccination, and pre-pandemic healthcare utilization. RESULTS: Among 6508 eligible COVIDEO patients, 4763 (73.1%) were matched to ≥1 non-COVIDEO patient. COVIDEO care was protective against the primary composite outcome (adjusted odds ratio [aOR] 0.91, 95% CI, 0.82-1.02), with a reduction in ED visits (7.8% vs. 9.6%; aOR 0.79, 95% CI, 0.70-0.89), but increase in hospitalizations (3.8% vs. 2.7%, aOR 1.37, 95% CI, 1.14-1.63) reflecting more direct-to-ward admissions (1.3% vs. 0.2%, p < 0.0001). Results were similar when matched comparators were limited to patients who had not received virtual care elsewhere with a decrease in ED visits (7.8 vs. 8.6%, aOR 0.86, 95% CI, 0.75-0.99) and an increase in hospitalizations (3.7 vs. 2.4%, aOR 1.45, 95% CI, 1.17-1.80). DISCUSSION: An intensive remote care programme can prevent unnecessary ED visits and facilitate direct-to-ward hospitalizations and thereby mitigate the impact of COVID-19 on the healthcare system.

Antimicrobial resistance and mortality following E. coli bacteremia.

Background: Global estimates suggest millions of deaths annually are associated with antimicrobial resistance (AMR) but these are generated from scarce data on the relative risk of death attributable to drug-resistant versus drug-sensitive infections. Methods: We examined all episodes of E. coli bloodstream infection in Ontario, Canada between 2017 and 2020, and measured 90 day mortality among those with resistant versus sensitive isolates for each of 8 commonly used antibiotic classes and a category of difficult to treat resistance (DTTR). We used multivariable logistic regression to calculate an adjusted odds of mortality associated with AMR, after accounting for patient demographics, comorbidities, and prior healthcare exposure. Findings: Among 14,548 eligible episodes of E. coli bloodstream infection, resistance was most common to aminopenicillins (46.8%), followed by first generation cephalosporins (38.8%), fluoroquinolones (26.5%), sulfonamides (24.1%), third generation cephalosporins (13.8%), aminoglycosides (11.7%), beta-lactam-beta-lactamase-inhibitors (9.1%) and carbapenems (0.2%). Only 18 (0.1%) episodes exhibited DTTR. For each antibiotic class, the unadjusted odds of mortality (OR) were higher among resistant isolates, but after accounting for patient characteristics the adjusted odds (aOR) of mortality were attenuated: aminopenicillins (OR 1.22, 95% CI 1.12-1.33; aOR 1.09, 95% CI 0.99-1.20), first generation cephalosporins (OR 1.24, 95% CI 1.14-1.35; aOR 1.07, 95% CI 0.97-1.18), third generation cephalosporins (OR 1.64, 95% CI 1.47-1.82; aOR 1.29, 95% CI 1.15-1.46), beta-lactam-beta-lactamase-inhibitors (OR 1.69, 95% CI 1.52-1.89, aOR 1.28, 95% CI 1.13-1.45), carbapenems (OR 3.11, 95% CI 1.52-6.34; aOR 2.06, 95% CI 0.91-4.66), sulfonamides (OR 1.19, 95% CI 1.07-1.31, aOR 1.06, 95% CI 0.95-1.18), fluoroquinolones (OR 1.49, 95% CI 1.36-1.64, aOR 1.16, 95% CI 1.05-1.29), aminoglycosides (OR 1.43, 95% CI 1.27-1.62; aOR 1.27, 95% CI 1.11-1.46), and DTTR (OR 3.71, 95% CI 1.46-9.41; aOR 2.58, 95% CI 0.87-7.66). Interpretation: AMR is associated with substantial increased mortality among patients with E. coli bloodstream infection, particularly for resistance to classes commonly used as empiric treatment. Surveillance for AMR-associated mortality should incorporate adjustment for patient characteristics and prior healthcare utilization. Funding: This work was supported by a project grant from CIHR (grant number 159503). This study was also supported by ICES, which is funded by an annual grant from Ontario Ministry of Health and Long-Term Care (MOHLTC).

Highly versus less bioavailable oral antibiotics in the treatment of gram-negative bloodstream infections: a propensity-matched cohort analysis.

OBJECTIVES: In this study, we evaluated the clinical outcomes associated with the use of highly bioavailable oral antibiotics (fluoroquinolones and trimethoprim-sulfamethoxazole) compared with the less-bioavailable oral antibiotics (ß-lactams) in gram-negative bloodstream infections (BSIs). METHODS: Among hospitalized older adult patients in Ontario, Canada, discharged home on oral treatment for gram-negative BSI between 1 January 2017 and 31 December 2019, we used a matched cohort design to compare outcomes among those receiving highly versus less-bioavailable agents; hard-matching 1:1 on sex, BSI pathogen (Escherichia coli vs. non-E. coli), and infection source (urinary vs. non-urinary/unknown source) along with a propensity score, incorporating specific pathogen, patient, and infection characteristics. The primary outcome was the composite of 90-day all-cause mortality, recurrent BSI with the same pathogen (genus and species), and re-admission to any Ontario hospital. RESULTS: A total of 2012 patients were included in the study (1006 in each bioavailability category). Those who received highly (compared with less) bioavailable antibiotics at discharge had lower rates of the composite outcome (171/1006 [17.0%] vs. 216/1006 [21.5%]), adjusted odds ratio being 0.74 (95% CI, 0.60-0.92). Recurrent BSI at 90 days was the main driver for the composite outcome occurring in 64 (5.4%) and 107 (9.4%) patients of the highly and less-bioavailable groups, respectively (p < 0.001) (adjusted odds ratio, 0.56; 95% CI, 0.40-0.78). DISCUSSION: Use of highly (compared with less) bioavailable antibiotics at discharge was associated with significantly better clinical outcomes among patients with gram-negative BSIs.

PNC-27, a Chimeric p53-Penetratin Peptide Binds to HDM-2 in a p53 Peptide-like Structure, Induces Selective Membrane-Pore Formation and Leads to Cancer Cell Lysis.

PNC-27, a 32-residue peptide that contains an HDM-2 binding domain and a cell-penetrating peptide (CPP) leader sequence kills cancer, but not normal, cells by binding to HDM-2 associated with the plasma membrane and induces the formation of pores causing tumor cell lysis and necrosis. Conformational energy calculations on the structure of PNC-27 bound to HDM-2 suggest that 1:1 complexes form between PNC-27 and HDM-2 with the leader sequence pointing away from the complex. Immuno-scanning electron microscopy was carried out with cancer cells treated with PNC-27 and decorated with an anti-PNC-27 antibody coupled to 6 nm gold particles and an anti-HDM-2 antibody linked to 15 nm gold particles. We found multiple 6 nm- and 15 nm-labeled gold particles in approximately 1:1 ratios in layered ring-shaped structures in the pores near the cell surface suggesting that these complexes are important to the pore structure. No pores formed in the control, PNC-27-treated untransformed fibroblasts. Based on the theoretical and immuno-EM studies, we propose that the pores are lined by PNC-27 bound to HDM-2 at the membrane surface with the PNC-27 leader sequence lining the pores or by PNC-27 bound to HDM-2.

Pool size measurements improve precision of flux estimates but increase sensitivity to unmodeled reactions outside the core network in isotopically nonstationary metabolic flux analysis (INST-MFA).

Metabolic flux analysis (MFA) involves model-based estimation of metabolic reaction rates (i.e., fluxes) and, in some cases, metabolite content (i.e., pool sizes) from experimental measurements. Applying MFA to biological data helps determine the fate of substrates and the activity of specific pathways within metabolic networks. However, reliably estimating fluxes by using simplified "core" models to predict the dynamics of larger metabolic networks remains a challenge. One point of uncertainty relates to the advantages and potential pitfalls of including pool size measurements as experimental inputs for isotopically nonstationary MFA (INST-MFA). Here, we directly assessed the role of pool sizes using various core models and simulated datasets. To investigate the effects of pool size measurements on INST-MFA, we assessed the accuracy and precision of flux estimates obtained using different subsets of data (e.g., with or without pool size measurements) and simple network models that either matched or differed from the true network. The inclusion of pool size measurements provided incremental improvements to the precision of the flux estimates. However, adding pool size measurements increased the sensitivity of the flux solution to unmodeled reactions outside the core network. These results were confirmed using a large Escherichia coli model that is representative of realistic metabolic networks examined in MFA studies. Our findings indicate that accurate flux estimates can be obtained in the absence of pool size measurements, even when using core models that lack full network coverage. Addition of pool size measurements to INST-MFA datasets may reveal the activity of non-core reactions that influence the labeling dynamics and therefore necessitate network expansion in order to reconcile all available data to the model. Our findings also emphasize the key role that goodness-of-fit testing plays in assessing the quality of model fits obtained with INST-MFA.

This is a handcraft: valuation, morality, and the social meanings of payments for psychoanalysis.

This article examines valuation and payment practices of psychoanalysts in Buenos Aires, Argentina. Psychoanalysts do not use explicit sliding scales but rather reach an agreement about fees in conversation with the patient. This negotiation is conducted with some principles of gift-giving, where parties try to give more, rather than through competitive bargaining (an inverted bazaar). Drawing on the sociology of money, morals and markets, and valuation studies literatures, I distinguish four factors to explain this: 1) Some formally produced prices as well as market mechanisms shape benchmarks for fees, but the peculiar service psychologists offer (which makes quality judgments hard), the way patients and therapists are matched, and the lack of public information about prices allow for high flexibility in price-setting; these are structural factors that remain unsaid in the conversation on fees. 2) A professional narrative that highlights a responsibility towards patients that should not be contaminated by economic interest. 3) Psychoanalysts' elaborations on the meanings of the payment, which should reflect the uniqueness of each patient and the bond analyst-patient and symbolize the patient's commitment to treatment, involving a cost and a loss beyond the economic. 4) The prevalence of cash, face-to-face payment without intermediaries, which helps desacralize the analyst and disentangle the session from the rest of the economic life of the analyst, but impedes evading moralization of the transaction. Payments in psychoanalysis are delicate arrangements, and analysts often stress about valuation and payments. They have to be careful to ensure this flexibility results in morally acceptable transactions.

Predicting population health with machine learning: a scoping review.

OBJECTIVE: To determine how machine learning has been applied to prediction applications in population health contexts. Specifically, to describe which outcomes have been studied, the data sources most widely used and whether reporting of machine learning predictive models aligns with established reporting guidelines. DESIGN: A scoping review. DATA SOURCES: MEDLINE, EMBASE, CINAHL, ProQuest, Scopus, Web of Science, Cochrane Library, INSPEC and ACM Digital Library were searched on 18 July 2018. ELIGIBILITY CRITERIA: We included English articles published between 1980 and 2018 that used machine learning to predict population-health-related outcomes. We excluded studies that only used logistic regression or were restricted to a clinical context. DATA EXTRACTION AND SYNTHESIS: We summarised findings extracted from published reports, which included general study characteristics, aspects of model development, reporting of results and model discussion items. RESULTS: Of 22 618 articles found by our search, 231 were included in the review. The USA (n=71, 30.74%) and China (n=40, 17.32%) produced the most studies. Cardiovascular disease (n=22, 9.52%) was the most studied outcome. The median number of observations was 5414 (IQR=16 543.5) and the median number of features was 17 (IQR=31). Health records (n=126, 54.5%) and investigator-generated data (n=86, 37.2%) were the most common data sources. Many studies did not incorporate recommended guidelines on machine learning and predictive modelling. Predictive discrimination was commonly assessed using area under the receiver operator curve (n=98, 42.42%) and calibration was rarely assessed (n=22, 9.52%). CONCLUSIONS: Machine learning applications in population health have concentrated on regions and diseases well represented in traditional data sources, infrequently using big data. Important aspects of model development were under-reported. Greater use of big data and reporting guidelines for predictive modelling could improve machine learning applications in population health. REGISTRATION NUMBER: Registered on the Open Science Framework on 17 July 2018 (available at https://osf.io/rnqe6/).

Low Energy Conformations for S100 Binding Peptide from the Negative Regulatory Domain of p53.

We have computed the low energy conformations of the negative regulatory domain of p53, residues 374-388 using Empirical Conformational Energies of Peptides Program including solvation and computed the statistical weights of distinct conformational states. We find that there are two high probability conformations, one an α-helix from Lys 374-Lys 381, followed by another helical structure involving Lys 382-Glu 388 (statistical weight of 0.48) and an all-α-helix for the entire sequence (statistical weight of 0.23). Both structure are superimposable on the NMR structure of this sequence bound to the S100 protein. The global minimum structure (statistical weight of 0.014) is a beta structure from Gly 374-Arg 379 followed by an α-helix from His 380-Glu 388. Based on these results, we propose a possible strategy for enhancement of p53 anti-tumor activity in cancer cells. Since the structure of this sequence bound to the sirtuin protein, Sir2, is a ß-sheet, we further propose that the global minimum may be an intermediate on the α-ß structure transition.

RAS-RAF-MEK-dependent oxidative cell death involving voltage-dependent anion channels.

Therapeutics that discriminate between the genetic makeup of normal cells and tumour cells are valuable for treating and understanding cancer. Small molecules with oncogene-selective lethality may reveal novel functions of oncoproteins and enable the creation of more selective drugs. Here we describe the mechanism of action of the selective anti-tumour agent erastin, involving the RAS-RAF-MEK signalling pathway functioning in cell proliferation, differentiation and survival. Erastin exhibits greater lethality in human tumour cells harbouring mutations in the oncogenes HRAS, KRAS or BRAF. Using affinity purification and mass spectrometry, we discovered that erastin acts through mitochondrial voltage-dependent anion channels (VDACs)--a novel target for anti-cancer drugs. We show that erastin treatment of cells harbouring oncogenic RAS causes the appearance of oxidative species and subsequent death through an oxidative, non-apoptotic mechanism. RNA-interference-mediated knockdown of VDAC2 or VDAC3 caused resistance to erastin, implicating these two VDAC isoforms in the mechanism of action of erastin. Moreover, using purified mitochondria expressing a single VDAC isoform, we found that erastin alters the permeability of the outer mitochondrial membrane. Finally, using a radiolabelled analogue and a filter-binding assay, we show that erastin binds directly to VDAC2. These results demonstrate that ligands to VDAC proteins can induce non-apoptotic cell death selectively in some tumour cells harbouring activating mutations in the RAS-RAF-MEK pathway.

Cetuximab shows activity in colorectal cancer patients with tumors that do not express the epidermal growth factor receptor by immunohistochemistry.

PURPOSE: To establish evidence of activity, or lack thereof, of cetuximab-based therapy in patients with refractory colorectal cancer with tumors that do not demonstrate epidermal growth factor receptor (EGFR) expression by immunohistochemistry (IHC). PATIENTS AND METHODS: Pharmacy computer records were reviewed to identify all patients who received cetuximab at Memorial Sloan-Kettering Cancer Center in a nonstudy setting during the first 3 months of cetuximab's commercial availability. Medical records of these patients were then reviewed to identify colorectal cancer patients who had experienced failure with a prior irinotecan-based regimen and who had a pathology report indicating an EGFR-negative tumor by IHC. Pathology slides from these patients were reviewed by a reference pathologist to confirm EGFR negativity, and computed tomography scans during cetuximab-based therapy were reviewed by a reference radiologist. Response rates were reported using WHO criteria. RESULTS: Sixteen chemotherapy-refractory, EGFR-negative colorectal cancer patients who received cetuximab in a nonstudy setting were identified. Fourteen of these patients received cetuximab plus irinotecan, and two received cetuximab monotherapy. In the 16 patients, four major objective responses were seen (response rate, 25%; 95% CI, 4% to 46%). CONCLUSION: Colorectal cancer patients with EGFR-negative tumors have the potential to respond to cetuximab-based therapies. EGFR analysis by current IHC techniques does not seem to have predictive value, and selection or exclusion of patients for cetuximab therapy on the basis of currently available EGFR IHC does not seem warranted.

Olho seco: conceitos, história natural e classificações / Dry eye: conceps, natural history and classifications

A síndrome do olho seco constitui freqüentemente, grande fonte de frustração, tanto para os pacientes, como para os oftalmologistas que, não raramente, são vencidos pela persistência dos sintomas, apesar dos esforços para sua abordagem diagnóstica e terapêutica. O tema adquire sua real importância quando nos defrontamos com o fato do olho seco ser uma das queixas mais comuns na prática oftalmológica. Os autores apresentam uma revisão de aspectos essenciais para a compreensão da moderna abordagem desta síndrome.

Perfil cardiopulmonar do paciente submetido à cirurgia de catarata / Cardiopulmonar outline undergone cataract surgery

Foi estudado um grupo de 285 pacientes portadores de catarata submetidos a um protocolo de avaliaçäo pré-anestésica, com o objetivo de determinar a distribuiçäo em relaçäo ao sexo e faixa etária das doenças sistêmicas mais prevalentes na amostra. A média da idade foi de 69,9 +/- 11,57 anos, e o predomínio foi do sexo feminino, com 172 casos. A distribuiçäo das afecçöes por faixa etária ocorreu de forma similar para ambos os sexos. Entre as patologias, predominaram as doenças cardiovasculares, a hipertensäo arterial sistêmica (HAS) foi a afecçäo mais prevalente, ocorrendo em 162 pacientes. Os valores pressóricos foram distribuídos por faixa etária segundo a classificaçäo do V JOINT, com o predomínio de portadores de HAS classe I, com 109 casos. Outras doenças cardiovasculares detectadas foram angina, com 55 pacientes, arritmias (36) e bloqueio de ramo (29). Entre as pneumopatias, a doença pulmonar obstrutiva crônica predominou, com 39 casos, seguida por asma (7) e tuberculose (6)