Predictive Value of LACE Scores for Pediatric Readmissions

INTRODUCTION

Hospital readmissions are recognized as a prevalent, yet potentially preventable, personal and economic burden. Length of stay, Acuity of admission, Comorbidities, and number of Emergency Department visits in the preceding 6 months can be quantified into one score, the LACE score. LACE scores have previously been identified to correlate with hospital readmissions within 30 days of discharge, but research specific to the pediatric population is scant. The objective of the present study was to investigate if LACE scores, in addition to other factors, can be utilized to create a predictive pediatric hospital readmission model that may ultimately be used to decrease readmission rates.

METHODS

This study included 25,616 hospitalizations of patients under the age of 18 years. Data were extracted from a hospital network electronic medical record. Demographics included LACE scores, age, gender, race/ethnicity, median household income, and medical centers. The primary exposure variable was LACE score. The main outcome measures were readmissions within 7, 14, and 30 days. The area under the curve (AUC) was used to assess the predictive capability of the regression model on patient 30-day admission.

RESULTS

LACE scores, age, gender, race/ethnicity, median household income, and medical centers were examined in a multivariable model to assess patient risk of a 30-day readmission. Only age and LACE score were observed to be statistically significant. The AUC for the combined model was 0.69.

DISCUSSION

As only age and LACE score were observed to be statistically significant and the AUC for the combined model was 0.69, this model is considered to have poor predictive capability.

CONCLUSIONS

In this study, LACE scores, as well the other factors, had a poor predictive capability for pediatric readmissions.

Influence of the Sequence Motive Repeating Number on Protein Folding in Spider Silk Protein Films

Like multiblock copolymers, spider silk proteins are built of repetitive sequence motives. One prominent repetitive motif is based on the consensus sequence of spidroin 4 of the spider Araneus diadematus ADF4. The number x of the repeating sequence motives (C) determines the molecular weight of the recombinant ADF4-based, engineered spider silk protein denoted as eADF4(Cx). eADF4(Cx) can be used as a model for intrinsically disordered proteins (IDP) and to elucidate their folding. Herein, the influence of the variation of the sequence motive repeating number x (x = 1, 2, 4, 8, 16) on the protein folding within eADF4(Cx) films was investigated. eADF4(Cx) films were cast from 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) solutions onto planar silicon model substrates, revealing mainly helical or random coil structure. Upon treatment with methanol vapor (ptm), the formation of crystalline β-sheets was triggered. Dichroic Fourier-transform infrared (FTIR) spectroscopy, circular dichroism, spectroscopic ellipsometry, atomic force microscopy, grazing-incidence small-angle X-ray scattering (GISAXS), grazing-incidence wide-angle X-ray scattering (GIWAXS), and electrokinetic and contact angle measurements were used to get information concerning the secondary structure and folding kinetics, orientation of β-sheets, the ratio of parallel/antiparallel β-sheets, domain sizes and distributions, surface topography, surface potential, hydrophobicity and the film integrity under water. Significant differences in the final β-sheet content, the share of antiparallel β-sheet structures, film integrity, surface potential, and isoelectric points between eADF4(Cx) with x = 1, 2 and eADF4(Cx) with x = 4, 8, 16 gave new insights in the molecular weight-dependent structure formation and film properties of IDP systems. GISAXS and kinetic measurements confirmed a relation between β-sheet crystal growth rate and final β-sheet crystal size. Further, competing effects of reduced diffusibility hindering accelerated crystal growth and enhanced backfolding promoting accelerated crystal growth with increasing molecular weight were discussed.

Factors Influencing Properties of Spider Silk Coatings and Their Interactions within a Biological Environment

Biomaterials are an indispensable part of biomedical research. However, although many materials display suitable application-specific properties, they provide only poor biocompatibility when implanted into a human/animal body leading to inflammation and rejection reactions. Coatings made of spider silk proteins are promising alternatives for various applications since they are biocompatible, non-toxic and anti-inflammatory. Nevertheless, the biological response toward a spider silk coating cannot be generalized. The properties of spider silk coatings are influenced by many factors, including silk source, solvent, the substrate to be coated, pre- and post-treatments and the processing technique. All these factors consequently affect the biological response of the environment and the putative application of the appropriate silk coating. Here, we summarize recently identified factors to be considered before spider silk processing as well as physicochemical characterization methods. Furthermore, we highlight important results of biological evaluations to emphasize the importance of adjustability and adaption to a specific application. Finally, we provide an experimental matrix of parameters to be considered for a specific application and a guided biological response as exemplarily tested with two different fibroblast cell lines.

β-Sheet Structure Formation within Binary Blends of Two Spider Silk Related Peptides

Intrinsically disordered proteins (IDPs) play an important role in molecular biology and medicine because their induced folding can lead to so-called conformational diseases, where β-amyloids play an important role. Still, the molecular folding process into the different substructures, such as parallel/antiparallel or extended β-sheet/crossed β-sheet is not fully understood. The recombinant spider silk protein eADF4(Cx) consisting of repeating modules C, which are composed of a crystalline (pep-c) and an amorphous peptide sequence (pep-a), can be used as a model system for IDP since it can assemble into similar structures. In this work, blend films of the pep-c and pep-a sequences were investigated to modulate the β-sheet formation by varying the molar fraction of pep-c and pep-a. Dichroic Fourier-transform infrared spectroscopy (FTIR), circular dichroism, spectroscopic ellipsometry, atomic force microscopy, and IR nanospectroscopy were used to examine the secondary structure, the formation of parallel and antiparallel β-sheets, their orientation, and the microscopic roughness and phase formation within peptide blend films upon methanol post-treatment. New insights into the formation of filament-like structures in these silk blend films were obtained. Filament-like structures could be locally assigned to β-sheet-rich structures. Further, the antiparallel or parallel character and the orientation of the formed β-sheets could be clearly determined. Finally, the ideal ratio of pep-a and pep-c sequences found in the fibroin 4 of the major ampullate silk of spiders could also be rationalized by comparing the blend and spider silk protein systems.

Structure-Property Relationship Based on the Amino Acid Composition of Recombinant Spider Silk Proteins for Potential Biomedical Applications

Improving biomaterials by engineering application-specific and adjustable properties is of increasing interest. Most of the commonly available materials fulfill the mechanical and physical requirements of relevant biomedical applications, but they lack biological functionality, including biocompatibility and prevention of microbial infestation. Thus, research has focused on customizable, application-specific, and modifiable surface coatings to cope with the limitations of existing biomaterials. In the case of adjustable degradation and configurable interaction with body fluids and cells, these coatings enlarge the applicability of the underlying biomaterials. Silks are interesting coating materials, e.g., for implants, since they exhibit excellent biocompatibility and mechanical properties. Herein, we present putative implant coatings made of five engineered recombinant spider silk proteins derived from the European garden spider Araneus diadematus fibroins (ADF), differing in amino acid sequence and charge. We analyzed the influence of the underlying amino acid composition on wetting behavior, blood compatibility, biodegradability, serum protein adsorption, and cell adhesion. The outcome of the comparison indicates that spider silk coatings can be engineered for explicit biomedical applications.

Crosslinked polypeptide films via RAFT mediated continuous assembly of polymers

Polypeptide coatings are a cornerstone in the field of surface modification due to their widespread biological potential. As their properties are dictated by their structural features, subsequent control thereof using unique fabrication strategies is important. Herein, we report a facile method of precisely creating densely crosslinked polypeptide films with unusually high random coil conformations through continuous assembly polymerization via reversible addition-fragmentation chain transfer (CAP-RAFT). CAP-RAFT was fundamentally investigated using methacrylated poly- L -lysine (PLLMA) and methacrylated poly- L -glutamic acid (PLGMA). Careful technique refinement resulted in films up to 36.1 ± 1.1 nm thick which could be increased to 94.9 ± 8.2 nm after using this strategy multiple times. PLLMA and PLGMA films were found to have 30-50% random coil conformations. Degradation by enzymes present during wound healing reveals potential for applications in drug delivery and tissue engineering.

Designing of spider silk proteins for human induced pluripotent stem cell-based cardiac tissue engineering

Materials made of recombinant spider silk proteins are promising candidates for cardiac tissue engineering, and their suitability has so far been investigated utilizing primary rat cardiomyocytes. Herein, we expanded the tool box of available spider silk variants and demonstrated for the first time that human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes attach, contract, and respond to pharmacological treatment using phenylephrine and verapamil on explicit spider silk films. The hiPSC-cardiomyocytes contracted for at least 14 days on films made of positively charged engineered Araneus diadematus fibroin 4 (eADF4(κ16)) and three different arginyl-glycyl-aspartic acid (RGD)-tagged spider silk variants (positively or negatively charged and uncharged). Notably, hiPSC-cardiomyocytes exhibited different morphologies depending on the spider silk variant used, with less spreading and being smaller on films made of eADF4(κ16) than on RGD-tagged spider silk films. These results indicate that spider silk engineering is a powerful tool to provide new materials suitable for hiPSC-based cardiac tissue engineering.

•

hiPSC-cardiomyocytes attach and contract on positively charged and/or RGD-tagged spider silk variants.

•

hiPSC-cardiomyocytes exhibit spider silk variant-dependent morphology upon adhesion.

•

Explicit spider silk variants promote long-term contractility of hiPSC-cardiomyocytes.

•

hiPSC-cardiomyocytes grown on spider silk materials respond to pharmacological treatment.

Dichroic Fourier Transform Infrared Spectroscopy Characterization of the β-Sheet Orientation in Spider Silk Films on Silicon Substrates

Orientation analysis of the β-sheet structure within films of the established recombinant spider silk protein eADF4(C16) was performed using a concept based on dichroic transmission- and attenuated total reflection-Fourier transform infrared spectroscopy, lineshape analysis, assignment of amide I components to specific vibration modes, and transition dipole moment directions of β-sheet structures. Based on the experimental dichroic ratio R, the order parameter S of β-sheet structures was calculated with respect to uniaxial orientation. Films of eADF4(C16) were deposited on untexturized (Si) and unidirectionally scratched silicon substrates (Si-sc) and post-treated with MeOH vapor. Freshly cast thin and thick eADF4(C16) films out of hexafluoroisopropanol featured β-sheet contents of ≈6%, which increased to >30% after MeOH post-treatment in dependence of time. Pseudo-first order folding kinetics were obtained, suggesting a transition from an unfolded to a folded state. In MeOH post-treated thin films with diameters in the nanometer range, a significant orientation of β-sheets was obtained regardless of the texturization of the silicon substrate (Si, Si-sc). This was rationalized by dichroic ratios of the amide I component at 1696 cm^-1 assigned to the (0, π) mode of antiparallel β-sheet structures, whose transition dipole moment M is located in parallel to both β-sheet plane and chain direction. The calculated high molecular order parameter S ≈ 0.40 suggested vertically (out-of-plane) oriented antiparallel β-sheet stacks with tilt angles of γ ≈ 39° to the surface normal. Microscale (thick) films, in contrast, revealed low order parameters S ≈ 0. Scanning force microscopy on thin eADF4 films at silicon substrates showed dewetted polymer film structures rather at the micro-scale. These findings give new insights in the role of the β-sheet crystallite orientation for the mechanical properties of spider silk materials.

Surface Modification of Spider Silk Particles to Direct Biomolecular Corona Formation

In recent years, spider silk-based materials have attracted attention because of their biocompatibility, processability, and biodegradability. For their potential use in biomaterial applications, i.e., as drug delivery systems and implant coatings for tissue regeneration, it is vital to understand the interactions between the silk biomaterial surface and the biological environment. Like most polymeric carrier systems, spider silk material surfaces can adsorb proteins when in contact with blood, resulting in the formation of a biomolecular corona. Here, we assessed the effect of surface net charge of materials made of recombinant spider silk on the biomolecular corona composition. In-depth proteomic analysis of the biomolecular corona revealed that positively charged spider silk materials surfaces interacted predominantly with fibrinogen-based proteins. This fibrinogen enrichment correlated with blood clotting observed for both positively charged spider silk films and particles. In contrast, negative surface charges prevented blood clotting. Genetic engineering allows the fine-tuning of surface properties of the spider silk particles providing a whole set of recombinant spider silk proteins with different charges or peptide tags to be used for, for example, drug delivery or cell docking, and several of these were analyzed concerning the composition of their biomolecular corona. Taken together this study demonstrates how the surface net charge of recombinant spider silk surfaces affects the composition of the biomolecular corona, which in turn affects macroscopic effects such as fibrin formation and blood clotting.

Fabrication and optical enhancing properties of discrete supercrystals

Discrete gold nanoparticle crystals with tunable size and morphology are fabricated via a fast and inexpensive template-assisted method. The highly precise hierarchical organization of the plasmonic building blocks yields superstructures with outstanding behaviour for surface-enhanced Raman scattering analysis.

[Mutation in factor II and factor V gene in patients with peripheral arterial occlusive disease]

Mutations in factor-V- and factor-II-genes are correlated with an increased risk for venous thrombosis according to the literature. The significance of the mutations in factor- II- and factor-V-genes for the development of the peripheral arterial occlusive disease is not known. Therefore, we investigated the presence of these mutations in 152 patients with documented peripheral arterial occlusive disease and 318 controls without peripheral arterial occlusive disease with polymerase chain reaction (PCR). There was no association between factor-II-mutation and peripheral arterial occlusive disease. The factor-V-mutation, however, was increased in patients with peripheral arterial occlusive disease double fold (12 positive cases in 318 controls, 12 positive cases in 152 patients with peripheral arterial occlusive disease). The significance level was reached (p = 0.05) in statistical analysis but the result did not fall below the significance level as necessary to reach statistical significance (odds ratio 2.19). Nevertheless, from these data we have to discuss a biological relevance of factor-V-mutation in the pathogenesis of peripheral arterial occlusive disease.

Chronisch-arterielle Verschlusskrankheit der Beine im Stadium IIb-IV

Die Faktor-V- und Faktor-II-Mutationen sind nach der Literatur mit einem erhöhten Risiko für venöse Thrombosen verbunden. Die Bedeutung der Mutationen im Faktor-IIund -V-Gen für die Entstehung und das Fortschreiten der arteriellen Verschlusskrankheit ist bislang nicht geklärt. Wir untersuchten das Vorhandensein dieser Mutationen bei 152 Patienten mit dokumentierter pAVK und 318 Kontrollen (ohne pAVK) mittels Polymerase-Kettenreaktion (PCR) und RFLP-Analyse. Die Ergebnisse erbrachten keinen Hinweis auf eine Assoziation zwischen einer Faktor-II-Mutation und der Entstehung einer pAVK. Dagegen waren Faktor- V-Mutationen bei pAVK-Patienten doppelt so häufig zu beobachten wie bei Gesunden (in der Kontrollgruppe ergaben sich 12 positive Fälle bei 318 Probanden, in der Patientengruppe ergaben sich 12 positive Fälle bei 152 Patienten). In der statistischen Analyse wurde das Signifikanzniveau (p = 0,05) zwar erreicht, aber nicht unterschritten. Das Chancenverhältnis (Odds-Ratio) betrug 2,19 (Konfidenzintervall 0,96-4,99). Schlussfolgerung: Die biologische Relevanz der Faktor-V-Mutation in der Pathogenese der pAVK kann aufgrund unserer Daten diskutiert werden.

[Chromogenic substrate as antidote against the thrombin inhibitor Melagatran?]

It could be shown in vitro that a chromogenic substrate (Chromozym TH, Roche Mannheim) acts at least partially as antidote against the new thrombin inhibitor Melagatran (AstraZeneca, Mölndal, Sweden). It is discussed that this antidote effect of a chromogenic substrate might be due to a substrate competition of fibrinogen, thrombin inhibitor, and chromogenic substrate for thrombin. Further animal experiments will clarify whether this in vitro observation is of practical relevance in vivo, too.

Chromogenes Substrat als Antidot gegen den Thrombininhibitor Melagatran?

Mit In-vitro-Untersuchungen wird gezeigt, dass ein chromogenes Substrat (Chromozym TH von Roche, Mannheim) die gerinnungshemmende Wirkung des neuen Thrombininhibitors Melagatran (AstraZeneca, Mölndal, Schweden) zumindest partiell antagonisieren kann. Der hier beschriebene Antidoteffekt eines chromogenen Substrats gegenüber einem Thrombininhibitor könnte seine Erklärung darin finden, dass eine Substratkompetition zwischen Thrombins im Testsystem und Fibrinogen, Thrombininhibitor und chromogenem Substrat vorliegt. Tierversuche unter Einbeziehung weiterer Thrombininhibitoren könnten klären, ob die beschriebene Antidotwirkung die beobachteten Blutungskomplikationen tatsächlich reduzieren kann oder ob ein In-vitro-Phänomen vorliegt, das in vivo wenig Relevanz besitzt.

Effect of gamma-interferon on binding of gliadin and other food peptides to the human intestinal cell line HT-29

gamma-Interferon is one of the main cytokines released during activation of intestinal lymphocytes in coeliac patients. The question has never been addressed whether gamma-interferon influences binding of gliadin and other food peptides to human enterocytes. Therefore, the human intestinal epithelial cell line HT-29 was cultured with gliadin, casein, beta-lactoglobulin and ovalbumin, with or without gamma-interferon, and peptide binding to cells was determined by flow cytometry and fluorescence microscopy. gamma-Interferon stimulated gliadin binding by a factor of 4. Binding was saturable with half maximal binding at 0.15 mg/ml. For maximal binding, an incubation of at least 24 h was necessary. gamma-Interferon increased binding of beta-lactoglobulin and casein, too, but inhibited that of ovalbumin. Binding of gliadin was inhibited by the other peptides. Under the conditions of ongoing mucosal inflammatory reactions and release of gamma-interferon, enhanced binding may trigger intestinal lymphocytes, increase secretion of cytokines and thus induce a vicious circle.

Reconstruction of pelvic exenterative wounds with transpelvic rectus abdominis flaps: a case series

Exenterative pelvic surgery is commonly performed for advanced carcinoma of the cervix and selected cases of locally advanced colorectal cancers. Low-lying lesions that are locally invasive in contiguous organs require resection of the perineal body en bloc with the resected specimen. The resulting defect, both in the pelvis and the perineum, creates a difficult management problem. Dead space in the pelvis, especially with adjunctive irradiation, leads to delayed wound healing and prolapse of small bowel into the pelvis. Small bowel obstruction and/or fistula formation are the greatest sources of morbidity in the operative group. Fifteen patients underwent exenterative pelvic procedures (total exenteration, 1 patient; posterior exenteration, 8 patients; abdominoperineal resection, 6 patients). All patients were reconstructed by transpelvic placement of the rectus abdominis muscle (muscle only, 4 patients; muscle with skin grafting, 8 patients; musculocutaneous, 3 patients). Eighty-seven percent received radiation therapy. One patient had Crohn's disease and all others had carcinoma. Healing was complete in 12 of 15 patients at discharge. There were no complications related to pelvic dead space (i.e., bowel obstruction, perineal fistula), with a mean follow-up time of 24.3 months. Small bowel was effectively excluded from the pelvis to the level of the acetabular roof by computerized axial tomography scan. The transpelvic rectus abdominis muscle flap is effective in preventing major morbidity after exenterative pelvic surgery.

"Medicine on wheels": an opportunity for outreach and housestaff education

Ambulatory-care teaching programs have been traditionally based in hospital settings. As many patients, in particular the homeless and underinsured, have never reached these settings, we describe a nontraditional outreach health-care program for medical residents. This multidisciplinary program places medical residents on a mobile van to deliver care to a population in New Haven where 18.2% of its families are below the poverty level and have limited or no access to health care at the teaching hospital. On-site urgent care is given along with HIV, pregnancy testing, and blood pressure screening. Health-care follow-up, dental care, alcohol detoxification, and drug counseling are scheduled. A total of 764 adult patients were seen between November 1991 and June 1993 by PGY2 residents on ambulatory rotations. One hundred forty-one patients consented to respond to a questionnaire. Thirty-seven (26%) were homeless with a mean length of homelessness of 15 months. Forty-one percent had been victimized within one year and 33% currently used illicit drugs. The benefits of this unique ambulatory teaching program for medical residents are described.

Cyclosporin enhancement of cisplatin chemotherapy in patients with refractory gynecologic cancer. A Gynecologic Oncology Group Study

BACKGROUND

Cyclosporin has been demonstrated to reverse resistance to several antineoplastic agents including cisplatin in vitro. The purpose of this Phase I trial was to study the potential clinical application of cyclosporin modulation of cisplatin and to establish a tolerable dose of cyclosporin when combined with a standard dose of cisplatin of 75 mg/m2.

METHODS

A course of therapy consisted of two cyclosporin infusions over 2 hours each, 24 hours apart, with cisplatin given 6 hours after the first dose. Treatment was repeated every 21 days. Cyclosporin was studied in a Phase I fashion at five different levels, from 1-5 mg/kg per dose. Twenty patients with refractory gynecologic cancer received 81 courses of therapy. All patients had received extensive prior chemotherapy containing cisplatin.

RESULTS

Grade 4 nephrotoxicity was seen in 4 of 20 patients: 1 treated at 1 mg/kg, 1 at 2 mg/kg, and 2 at 5 mg/kg of cyclosporin. The patient treated at the 1 mg/kg level was a partial clinical responder and tolerated six courses. The patient at the 2 mg/kg level had received 14 prior courses of cisplatin and tolerated only two additional courses before a Grade 4 renal toxicity developed. Grade 4 nephrotoxicity developed in the two patients receiving 5 mg after two courses of chemotherapy. Two of the 20 patients achieved a complete response (CR) and 3 patients achieved a partial response (PR), for a total response rate of 25% (5 of 20). The two women who achieved CR started treatment with symptomatic ascites; one of whom also had multiple pulmonary lesions that were no longer evident after three courses of therapy.

CONCLUSIONS

Cyclosporin at a dose of 4 mg/kg per day given for 2 consecutive days in association with 75 mg/m2 of cisplatin can be given with reasonable assurance of safety.