High dimensional predictions of suicide risk in 4.2 million US Veterans using ensemble transfer learning

We present an ensemble transfer learning method to predict suicide from Veterans Affairs (VA) electronic medical records (EMR). A diverse set of base models was trained to predict a binary outcome constructed from reported suicide, suicide attempt, and overdose diagnoses with varying choices of study design and prediction methodology. Each model used twenty cross-sectional and 190 longitudinal variables observed in eight time intervals covering 7.5 years prior to the time of prediction. Ensembles of seven base models were created and fine-tuned with ten variables expected to change with study design and outcome definition in order to predict suicide and combined outcome in a prospective cohort. The ensemble models achieved c-statistics of 0.73 on 2-year suicide risk and 0.83 on the combined outcome when predicting on a prospective cohort of [Formula: see text] 4.2 M veterans. The ensembles rely on nonlinear base models trained using a matched retrospective nested case-control (Rcc) study cohort and show good calibration across a diversity of subgroups, including risk strata, age, sex, race, and level of healthcare utilization. In addition, a linear Rcc base model provided a rich set of biological predictors, including indicators of suicide, substance use disorder, mental health diagnoses and treatments, hypoxia and vascular damage, and demographics.

Prioritizing vaccination based on analysis of community networks

Many countries that had early access to COVID-19 vaccines implemented vaccination strategies that prioritized health care workers and the elderly. As barriers to access eased, vaccine prioritization strategies have been relaxed. However, these strategies are still an important tool for decision makers to manage new variants, plan for future booster shots, or stage mass vaccinations. This paper explores the impact of vaccine prioritization strategies using networks that represent communities with different demographics and connectivity. The impact of vaccination is compared to non-medical intervention to reduce transmission. Several sources of uncertainty are considered, including vaccine willingness and mask effectiveness. This paper finds that while prioritization strategies can have a large impact on reducing deaths and peak hospitalization, selecting the best strategy depends on community characteristics and the desired objective. Additionally, in some cases random vaccination performs as well as more targeted prioritization strategies. Understanding these trade-offs is important when planning vaccine distribution.

MIC Discrepancies between Parenteral and Oral Anti-Staphylococcal Beta-Lactams among MSSA

INTRODUCTION

Recent evidence has shown that oral antibiotic therapy is not inferior to IV antibiotic therapy in the treatment of complicated Staphylococcus aureus infections. Therefore, oral antibiotic therapy is now frequently prescribed in clinical practice due to cost benefit, ease of administration, decreased complication rate, and lack of need for IV access. In vitro susceptibility testing for β-lactam oral antibiotics is not routinely performed as the guidelines provided by the Clinical and Laboratory Standards Institute (CLSI) recommend using oxacillin and cefoxitin as surrogate markers. Hence, oral antibiotic susceptibilities for cephalexin and dicloxacillin are not reported and implied based on oxacillin and cefoxitin. The objective of the current study was to determine whether susceptibilities among S. aureus isolates are predictable when comparing commonly used IV and oral beta-lactams.

METHODS

Cefazolin, cephalexin, dicloxacillin, and oxacillin broth microdilution minimum inhibitory concentrations (MICs) were determined for 100 clinical isolates of methicillin-sensitive S. aureus by broth microdilution following CLSI guidelines.

RESULTS

Among these isolates, median MICs for cephalexin were eight-fold higher than cefazolin MICs and median MICs for dicloxacillin were four-fold less than oxacillin MICs. Ten percent of more strains studied had a major or very major error in its susceptibility reporting when cephalexin was compared to its surrogate marker oxacillin.

DISCUSSIONS/CONCLUSIONS

The variations in MICs observed compounded with the dosing and pharmacokinetic differences of oral versus IV β-lactam suggests that establishing breakpoints for oral β-lactam antibiotics is necessary to ensure adequate therapy is selected for the treatment of complex S. aureus infections.

Examining the combination of cefixime and amoxicillin/clavulanate against extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates

INTRODUCTION

Community-acquired urinary tract infections (UTIs) caused by extended spectrum beta-lactamase (ESBL)-producing Escherichia coli have limited oral therapeutic options and pose significant clinical challenges. The goal of this study was to evaluate the in vitro synergy between CFM and AMC against ESBL E. coli with aims to identify an oral treatment option for UTIs.

METHODS

Minimum inhibitory concentrations (MICs) of CFM in the presence of AMC were determined for 46 clinical isolates by placing a CFM Etest on a plate with AMC impregnated in the agar. Isolates with CFM MIC ≤1 µg/ml in the presence of AMC were considered susceptible to the CFM and AMC combination. Five isolates were then selected for further testing using time-kill analysis in the presence of CFM, AMC, and CFM with AMC. Time-kill curves were plotted to determine synergy over 24 hours.

RESULTS

AMC improved the activity of CFM against ESBL E. coli isolates by 128-fold in the Etest analysis with 85% of tested isolates being susceptible to the combination. Four-fold or greater reduction in CFM MIC was exhibited in 44 of 46 (96%) isolates when in the presence of AMC. Synergy and bactericidal activity between CFM and AMC were exhibited in each of the five isolates tested by time-kill analysis.

DISCUSSION/CONCLUSION

This study found that AMC improves the activity of CFM against ESBL E. coli and that this antibiotic combination has potential as an oral therapeutic option to treat ESBL E. coli UTIs.

Role of contact system activation in hemodialyzer-induced thrombogenicity

BACKGROUND

The contact system is generally believed to be the main trigger of the coagulation cascade during extracorporeal circulation. However, the extent of contact activation, its role for intradialytic thrombin generation as well as the influence of different dialyzer membranes have not been well established.

METHODS

In a novel full-scale ex vivo recirculation dialysis model, we investigated the thrombogenicity of three widely used hemodialyzers (Cuprophan Renak RA15-U, Polysulfone F6HPS and AN69XT Nephral 200). The activation of the contact system was evaluated using a newly developed ELISA for factor XIIa-C1-inhibitor complexes. Additionally, we determined free FXIIa (ELISA), thrombin-antithrombin (TAT) complexes, platelet factor 4 (PF4), complement activation (C5a), granulocyte elastase and blood cell counts. The findings in blood from normal volunteers were compared with factor XII-deficient blood.

RESULTS

With normal blood AN69 exhibited the highest thrombogenicity in comparison to Cuprophan and Polysulfone, as assessed by TAT generation and platelet consumption. AN69 caused a rapid increase of the FXIIa-C1-inhibitor complexes and of free FXIIa. Despite significant TAT generation with Cuprophan and Polysulfone free FXIIa remained unchanged and the FXIIa-C1-inhibitor complexes stayed below the detection limit. With factor XII-deficient blood Polysulfone exhibited the same TAT generation, whereas the thrombogenicity of AN69 was greatly reduced.

CONCLUSIONS

Our data challenge the common assumption that activation of the contact system with generation of FXIIa is the main trigger for coagulation and thrombus formation in hemodialysis. Only the negatively charged AN69 membrane with enhanced thrombogenicity strongly induced contact activation.

Glutardialdehyde induced fluorescence technique (GIFT): a new method for the imaging of platelet adhesion on biomaterials

One of the major limitations of biomaterials used in medicine is the adhesion and subsequent activation of platelets upon contact with blood. The development of new or modified materials necessitates adequate methods for the detection and quantification of platelet/material interactions. These interactions are commonly investigated by means of scanning electron microscopy (SEM), radioisotope and immunological techniques, or by quantification of released platelet contents. Given the lack of a simple, rapid, and inexpensive assay, we developed a novel method for the accurate assessment of platelet adhesion after contact with foreign surfaces, which enables quantitative measurements as well as imaging of the platelet shape change, and which omits conventional or immunological staining and time-consuming preparative steps. The glutardialdehyde induced fluorescence technique (GIFT) uses the epifluorescence of glutardialdehyde-fixed platelets detected by fluorescence microscopy and is suitable for opaque and transparent materials. Combined with computer-aided image analysis, numbers of adherent platelets, platelet-covered surface, and average platelet spread area can be determined as markers of surface thrombogenicity. To validate the technique, four materials of different thrombogenicity [polypropylene (PP), poly(D,L-lactide) (PDLLA), 2-hydroxyethyl-methacrylate-grafted PDLLA (PDLLA-HEMA), and heparin-coupled PDLLA-HEMA] were investigated by GIFT and SEM. We found concordant results with SEM and GIFT with the following ranking of thrombogenicity: PP > PDLLA > PDLLA-HEMA > or = PDLLA-HEMA-heparin. GIFT significantly discriminated between the investigated materials. The surface modifications led to improved thromboresistance with reduced platelet adhesion and shape change. The main advantages of GIFT as compared with SEM are: no vacuum-drying or dehydration, less time-consuming procedure, fixation and fluorescence "staining" in one step, and suitability for computer-aided image analysis allowing quantitative assessment of platelet adhesion as well as imaging of the platelet shape change with high-contrast images. In conclusion, GIFT is a valid, rapid, and simple method for the quantitative determination of platelet/material interactions intended for the evaluation of thrombogenicity of biomaterials surfaces.

Application of a new dynamic flow model for investigating the biocompatibility of modified surfaces

An in vitro model was developed to compare the biocompatibility of four different coating methods (three heparin and one nonheparin) under hemodynamic conditions. Fresh human donor blood (heparin 5 IU/ml) was recirculated in a standardized experimental circuit. All circuit components were either coated or remained uncoated for control purposes. The aim of the study was to investigate a wide spectrum of effects on blood; coagulation parameters (e.g., fibrinogen, ATIII, thrombin-antithrombin-complex), complement parameters (C1rsC1 Inh, C3b(Bb)P, SC5b-9, C5a), differential blood analyses, platelet activation (flow cytometric investigations), PF 4, and PMN-elastase release were examined by showing possible trends. All heparin coated systems reduced platelet stimulation in comparison to untreated biomaterials. Leukocyte activation was reduced to different degrees depending upon the coating method used. Complement activation was markedly reduced by all coated systems. The results obtained indicate that the pump driven, dynamic blood flow model is suitable to characterize the biocompatibility of surface modified biomaterials. Advantages lie in the integration of the different polymers as parts of the circuit, the low priming volume, and the generation of blood flow conditions similar to those that occur in clinical applications.

Improvement of haemocompatibility of metallic stents by polymer coating

An alternative to open heart surgery in treating arterial diseases causing restricted blood flow is the implantation of intracoronary metallic stents. In spite of the advances in implantation and in spite of the excellent mechanical properties of metallic stents, there are still limitations because of the thrombogenicity of the metal. We have, hence, directed our attention to the coating of metallic stents with an ultrathin polymer layer by chemical vapor deposition (CVD) polymerization of 2-chloroparacyclophan. In a second step of surface modification the poly(2-chloroparaxylylene) layer is modified by treatment with a sulfur dioxide plasma in order to obtain a more hydrophilic surface with new functional groups. The results demonstrate the stable polymer coating of the stents and the improvement of haemocompatibility after treatment with sulfur dioxide plasma. Platelet adhesion is decreased from 85% for the metal surface to 20% for the CVD-coated and sulfur-dioxide-plasma treated surface.

A molecular aspect of hematopoiesis and endoderm development common to vertebrates and Drosophila

In vertebrates, transcriptional regulators of the GATA family appear to have a conserved function in differentiation and organ development. GATA-1, −2 and −3 are required for different aspects of hematopoiesis, while GATA-4, −5 and −6 are expressed in various organs of endodermal origin, such as intestine and liver, and are implicated in endodermal differentiation. Here we report that the Drosophila gene serpent (srp) encodes the previously described GATA factor ABF. The multiple functions of srp in Drosophila suggest that it is an ortholog of the entire vertebrate Gata family. srp is required for the differentiation and morphogenesis of the endodermal gut. Here we show that it is also essential for Drosophila hematopoiesis and for the formation of the fat body, the insect organ analogous to the liver. These findings imply that some aspects of the molecular mechanisms underlying blood cell development as well as endodermal differentiation are early acquisitions of metazoan evolution and may be common to most higher animals.

Development and characterization of a wettable surface modified aromatic polyethersulphone using glow discharge induced HEMA-graft polymerisation

The aromatic polyethersulphone (PES) is a well known polymer for the preparation of membranes with excellent thermal stability and chemical resistance. The disadvantage of PES-membranes is their hydrophobic character, which in contact with protein containing solutions leads to high protein adsorption and as a consequence to deterioration of membrane properties. In this report the surface modification of PES by means of glow discharge induced grafting of 2-hydroxyethyl methacrylate (HEMA) is described. Graft polymerisation creates a largely wettable layer of poly(2-hydroxyethyl methacrylate) (PHEMA) on the surface of PES. This has been shown by contact angle measurements using the Wilhelmy plate method. Chemical characterization is carried out by means of X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy/attentuated total reflection (FTIR-ATR). The influence of storage conditions on the surface properties of modified PES samples has been investigated after storage in vacuum, water, and air.