[Corneal epithelial biomechanics: Resistance to stress and role in healing and remodeling]

The corneal epithelium is one of the first tissue barriers of the eye against the environment. In recent years, many studies provided better knowledge of its healing, its behavior and its essential role in the optical system of the eye. At the crossroads of basic science and clinical medicine, the study of the mechanical stresses applied to the cornea makes it possible to learn the behavior of epithelial cells and better understand ocular surface disease. We describe herein the current knowledge about the adhesion systems of the corneal epithelium and their resistance to mechanical stress. We will also describe the involvement of these mechanisms in corneal healing and their role in epithelial dynamics. Adhesion molecules of the epithelial cells, especially hemidesmosomes, allow the tissue cohesion required to maintain the integrity of the corneal epithelium against the shearing forces of the eyelids as well as external forces. Their regeneration after a corneal injury is mandatory for the restoration of a healthy epithelium. Mechanotransduction plays a significant role in regulating epithelial cell behavior, and the study of the epithelium's response to mechanical forces helps to better understand the evolution of epithelial profiles after refractive surgery. A better understanding of corneal epithelial biomechanics could also help improve future therapies, particularly in the field of tissue engineering.

Surgical gestures as a method to quantify surgical performance and predict patient outcomes

How well a surgery is performed impacts a patient's outcomes; however, objective quantification of performance remains an unsolved challenge. Deconstructing a procedure into discrete instrument-tissue "gestures" is a emerging way to understand surgery. To establish this paradigm in a procedure where performance is the most important factor for patient outcomes, we identify 34,323 individual gestures performed in 80 nerve-sparing robot-assisted radical prostatectomies from two international medical centers. Gestures are classified into nine distinct dissection gestures (e.g., hot cut) and four supporting gestures (e.g., retraction). Our primary outcome is to identify factors impacting a patient's 1-year erectile function (EF) recovery after radical prostatectomy. We find that less use of hot cut and more use of peel/push are statistically associated with better chance of 1-year EF recovery. Our results also show interactions between surgeon experience and gesture types-similar gesture selection resulted in different EF recovery rates dependent on surgeon experience. To further validate this framework, two teams independently constructe distinct machine learning models using gesture sequences vs. traditional clinical features to predict 1-year EF. In both models, gesture sequences are able to better predict 1-year EF (Team 1: AUC 0.77, 95% CI 0.73-0.81; Team 2: AUC 0.68, 95% CI 0.66-0.70) than traditional clinical features (Team 1: AUC 0.69, 95% CI 0.65-0.73; Team 2: AUC 0.65, 95% CI 0.62-0.68). Our results suggest that gestures provide a granular method to objectively indicate surgical performance and outcomes. Application of this methodology to other surgeries may lead to discoveries on methods to improve surgery.

A multi-scale time-series dataset with benchmark for machine learning in decarbonized energy grids

The electric grid is a key enabling infrastructure for the ambitious transition towards carbon neutrality as we grapple with climate change. With deepening penetration of renewable resources, the reliable operation of the electric grid becomes increasingly challenging. In this paper, we present PSML, a first-of-its-kind open-access multi-scale time-series dataset, to aid in the development of data-driven machine learning (ML)-based approaches towards reliable operation of future electric grids. The dataset is synthesized from a joint transmission and distribution electric grid to capture the increasingly important interactions and uncertainties of the grid dynamics, containing power, voltage and current measurements over multiple spatio-temporal scales. Using PSML, we provide state-of-the-art ML benchmarks on three challenging use cases of critical importance to achieve: (i) early detection, accurate classification and localization of dynamic disturbances; (ii) robust hierarchical forecasting of load and renewable energy; and (iii) realistic synthetic generation of physical-law-constrained measurements. We envision that this dataset will provide use-inspired ML research in safety-critical systems, while simultaneously enabling ML researchers to contribute towards decarbonization of energy sectors.

Measurement(s)	temperature • wind speed • solar zeinth angle • dew point • irradiance • voltage • current
Technology Type(s)	weather station • power grid model-based simulation
Factor Type(s)	load power • renewable generation power • disturbance location, type, and duration

Interpretability and fairness evaluation of deep learning models on MIMIC-IV dataset

The recent release of large-scale healthcare datasets has greatly propelled the research of data-driven deep learning models for healthcare applications. However, due to the nature of such deep black-boxed models, concerns about interpretability, fairness, and biases in healthcare scenarios where human lives are at stake call for a careful and thorough examination of both datasets and models. In this work, we focus on MIMIC-IV (Medical Information Mart for Intensive Care, version IV), the largest publicly available healthcare dataset, and conduct comprehensive analyses of interpretability as well as dataset representation bias and prediction fairness of deep learning models for in-hospital mortality prediction. First, we analyze the interpretability of deep learning mortality prediction models and observe that (1) the best-performing interpretability method successfully identifies critical features for mortality prediction on various prediction models as well as recognizing new important features that domain knowledge does not consider; (2) prediction models rely on demographic features, raising concerns in fairness. Therefore, we then evaluate the fairness of models and do observe the unfairness: (1) there exists disparate treatment in prescribing mechanical ventilation among patient groups across ethnicity, gender and age; (2) models often rely on racial attributes unequally across subgroups to generate their predictions. We further draw concrete connections between interpretability methods and fairness metrics by showing how feature importance from interpretability methods can be beneficial in quantifying potential disparities in mortality predictors. Our analysis demonstrates that the prediction performance is not the only factor to consider when evaluating models for healthcare applications, since high prediction performance might be the result of unfair utilization of demographic features. Our findings suggest that future research in AI models for healthcare applications can benefit from utilizing the analysis workflow of interpretability and fairness as well as verifying if models achieve superior performance at the cost of introducing bias.

Survival Analysis Using Surgeon Skill Metrics and Patient Factors to Predict Urinary Continence Recovery After Robot-assisted Radical Prostatectomy

BACKGROUND

It has been shown that metrics recorded for instrument kinematics during robotic surgery can predict urinary continence outcomes.

OBJECTIVE

To evaluate the contributions of patient and treatment factors, surgeon efficiency metrics, and surgeon technical skill scores, especially for vesicourethral anastomosis (VUA), to models predicting urinary continence recovery following robot-assisted radical prostatectomy (RARP).

DESIGN, SETTING, AND PARTICIPANTS

Automated performance metrics (APMs; instrument kinematics and system events) and patient data were collected for RARPs performed from July 2016 to December 2017. Robotic Anastomosis Competency Evaluation (RACE) scores during VUA were manually evaluated. Training datasets included: (1) patient factors; (2) summarized APMs (reported over RARP steps); (3) detailed APMs (reported over suturing phases of VUA); and (4) technical skills (RACE). Feature selection was used to compress the dimensionality of the inputs.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The study outcome was urinary continence recovery, defined as use of 0 or 1 safety pads per day. Two predictive models (Cox proportional hazards [CoxPH] and deep learning survival analysis [DeepSurv]) were used.

RESULTS AND LIMITATIONS

Of 115 patients undergoing RARP, 89 (77.4%) recovered their urinary continence and the median recovery time was 166 d (interquartile range [IQR] 82-337). VUAs were performed by 23 surgeons. The median RACE score was 28/30 (IQR 27-29). Among the individual datasets, technical skills (RACE) produced the best models (C index: CoxPH 0.695, DeepSurv: 0.708). Among summary APMs, posterior/anterior VUA yielded superior model performance over other RARP steps (C index 0.543-0.592). Among detailed APMs, metrics for needle driving yielded top-performing models (C index 0.614-0.655) over other suturing phases. DeepSurv models consistently outperformed CoxPH; both approaches performed best when provided with all the datasets. Limitations include feature selection, which may have excluded relevant information but prevented overfitting.

CONCLUSIONS

Technical skills and "needle driving" APMs during VUA were most contributory. The best-performing model used synergistic data from all datasets.

PATIENT SUMMARY

One of the steps in robot-assisted surgical removal of the prostate involves joining the bladder to the urethra. Detailed information on surgeon performance for this step improved the accuracy of predicting recovery of urinary continence among men undergoing this operation for prostate cancer.

DL4Burn: Burn Surgical Candidacy Prediction using Multimodal Deep Learning

Burn wounds are most commonly evaluated through visual inspection to determine surgical candidacy, taking into account burn depth and individualized patient factors. This process, though cost effective, is subjective and varies by provider experience. Deep learning models can assist in burn wound surgical candidacy with predictions based on the wound and patient characteristics. To this end, we present a multimodal deep learning approach and a complementary mobile application - DL4Burn - for predicting burn surgical candidacy, to emulate the multi-factored approach used by clinicians. Specifically, we propose a ResNet50-based multimodal model and validate it using retrospectively obtained patient burn images, demographic, and injury data.

Breast Cancer Survivors’ Preferences and Barriers Related to ICT-Based Diet and Physical Activity Interventions

Objectives

To establish the preferences and perceived barriers related to physical activity and diet programming of breast cancer survivors (BCS) to inform the development of Information and Communication Technology (ICT)-based lifestyle interventions.

Methods

This was a cross-sectional study of 197 BSC aged 18 years or older and diagnosed with ductal carcinoma in situ (DCIS) or Stage I-IV breast cancer. The BCS were recruited during routine oncology appointments at a Midwestern cancer center. A survey was conducted to query survivors’ level of interest in, preferences for, and perceived barriers to participating in an exercise and dietary intervention program, with a specific emphasis on ICT-based programming.

Results

Overall, 85% of BCS reported they would consider participating in exercise and diet intervention research. Approximately 45% of participants reported that they had received diet and/or exercise information as part of their cancer care. However, only 15% of the participants received such information from healthcare professionals with the appropriate expertise (e.g., Dietitian, Exercise Specialist). Over two-thirds of the participants reported frequent use of mobile devices and the internet, and 80% indicated comfort using these devices (e.g., tablet, smart phone). The top three preferred formats for an ICT-based diet and exercise intervention program were “website”, “mobile apps” and “e-mails”. Older participants (>60 years) were more likely to report a preference for e-mails while younger participants (<60 years) were more likely to report a preference for websites or mobile apps. The most common perceived barriers to participation in a lifestyle intervention included fatigue, family responsibility and work.

Conclusions

Most BCS in this study were interested in exercise and diet interventions and would be comfortable with an ICT-based format with a preference for delivery via websites, mobile apps or e-mails. Future ICT-based lifestyle interventions should be designed with consideration of BCS’ age, barriers, facilitators and other characteristics.

Funding Sources

USDA-NIFA Hatch Project 1,011,487

[Intracorneal ring segments in keratoconus management]

Intracorneal ring segments (ICRS), used in the management of keratoconus since the 2000s, have enjoyed significant technological development. Various types of ICRS exist, whose arc length, thickness, and diameter can be chosen according to the desired effect on the spherical equivalent, keratometry and asphericity. Individualized implantation strategies, based on each patient's topographic and tomographic pattern, are constantly evolving. The surgical procedure is standardized, and complications remain very rare. Combined procedures (corneal collagen cross-linking and refractive photokeratectomy±topo-guided, phakic and pseudophakic intraocular lenses) are increasingly used and require a good knowledge of the effect of ICRS alone on the keratoconic cornea. The objective of this review is to summarize clinical practices used in the visual rehabilitation of keratoconic patients using the ICRS+- combined procedures.

An algorithm in ophthalmic emergencies to evaluate the necessity of physical consultation during COVID-19 lockdown in Paris: Experience of the first 100 patients

Purpose

This study aimed to evaluate the ability of a freely accessible internet algorithm to correctly identify the need for emergency ophthalmologic consultation for correct diagnosis and management.

Method

This retrospective observational cohort study was based on the first 100 patients who requested recommendations on the necessity of breaking the lockdown for emergency ophthalmology consultation during the period from March to May 2020.

Results

Ninety-one patients completed questionnaires. Forty-nine were directed to emergency consultation and 42 to differed scheduled visits or telemedicine visits. One patient sent for emergency consultation had an overestimated severity and could have been seen later, while two patients initially recommended for a scheduled visit were considered appropriate for emergency consultation. However, these patients’ management did not suffer as a consequence of the delay. The sensitivity of the algorithm, defined as the number of emergency consultations suggested by the algorithm divided by the total number of emergency consultations deemed appropriate by the practitioner's final evaluation, was 96.0%. The specificity of the algorithm, defined as the number of patients recommended for delayed consultation by the algorithm divided by the number of patients deemed clinically appropriate for this approach, was 97.5%. The positive predictive value, defined as the number of appropriate emergency consultations divided by the total number of emergency consultations suggested by the algorithm, was 97.9%. Finally, the negative predictive value, defined as the number of appropriately deferred patients divided by the number of deferred patients recommended by the algorithm, was 95.2%.

Conclusion

This study demonstrates the reliability of an algorithm based on patients’ past medical history and symptoms to classify patients and direct them to either emergency consultation or to a more appropriate deferred, scheduled appointment. This algorithm might allow reduction of walk-in visits by half and thus help control patient flow into ophthalmologic emergency departments.

Excimer laser programming of refractive astigmatism vs. anterior corneal astigmatism in the case of ocular residual astigmatism (ORA)

PURPOSE

To determine whether manifest refractive astigmatism (RA) or anterior corneal astigmatism (CA) is the best value for excimer laser programming in cases of ocular residual astigmatism (ORA).

PATIENTS AND METHODS

Patients who had undergone LASIK surgery with a disagreement between manifest refractive and corneal cylinder (ocular residual astigmatism ORA)>0.75 D were included retrospectively in this study. We calculated target induced astigmatism vector (TIA), surgically induced astigmatism vector (SIA), difference vector between the astigmatism correction programmed in the excimer laser and refractive astigmatism (DVRA), difference vector between the astigmatism correction programmed in the excimer laser and corneal astigmatism (DVCA) and difference vector between TIA and SIA (DV), by the Alpins method. Vectorial differences between DV and DVRA, and between DV and DVCA, were then calculated to determine whether RA or CA was closest to the ideal cylinder for laser programming.

RESULTS

Of a total of 104 eyes undergoing LASIK, 22 eyes of 12 patients (21.1%) had an ORA>0.75 D and were included. Mean ORA was 0.9±0.2 D and mean postoperative subjective cylinder was 0.45 D. The DV-DVRA difference vector was 0.57±0.2 D, and the DV-DVCA difference vector was 0.86±0.4 D (P=0.02). RA was closer than CA to the ideal astigmatism correction.

CONCLUSION

In cases of discrepancy between manifest astigmatism and corneal astigmatism, correction of manifest refractive astigmatism seems to give a better refractive result.

Involvement of CREB-regulated transcription coactivators (CRTC) in transcriptional activation of steroidogenic acute regulatory protein (Star) by ACTH

Studies in vivo have suggested the involvement of CREB-regulated transcription coactivator (CRTC)2 on ACTH-induced transcription of the key steroidogenic protein, Steroidogenic Acute Regulatory (StAR). The present study uses two ACTH-responsive adrenocortical cell lines, to examine the role of CRTC on Star transcription. Here we show that ACTH-induced Star primary transcript, or heteronuclear RNA (hnRNA), parallels rapid increases in nuclear levels of the 3 isoforms of CRTC; CRTC1, CRTC2 and CRTC3. Furthermore, ACTH promotes recruitment of CRTC2 and CRTC3 by the Star promoter and siRNA knockdown of either CRTC3 or CRTC2 attenuates the increases in ACTH-induced Star hnRNA. Using pharmacological inhibitors of PKA, MAP kinase and calcineurin, we show that the effects of ACTH on Star transcription and CRTC nuclear translocation depend predominantly on the PKA pathway. The data provides evidence that CRTC2 and CRTC3, contribute to activation of Star transcription by ACTH, and that PKA/CRTC-dependent pathways are part of the multifactorial mechanisms regulating Star transcription.

[SMILE (Small Incision Lenticule Extraction) among the corneal refractive surgeries in 2018 (French translation of the article)]

Refractive surgery is a field in constant evolution. In recent years, a new procedure has appeared under the name SMILE (Small Incision Lenticule Extraction). This technique, carried out solely with a femtosecond laser, should make it possible to better preserve corneal innervation and biomechanics. After a detailed review of the technique itself, we then focus on the scientific evidence for the safety and efficacy of SMILE and its current indications. Advantages of SMILE will be discussed in comparison to disadvantages of the conventional techniques, particularly concerning dry eye and the risk of corneal ectasia with LASIK. Lastly, the current limitations of SMILE (indications, retreatment) are discussed, and future applications are considered regarding improvements in the technique.

SMILE (Small Incision Lenticule Extraction) among the corneal refractive surgeries in 2018

Refractive surgery is a field in constant evolution. In recent years, a new procedure has appeared under the name SMILE (SMall Incision Lenticule Extraction). This technique, carried out solely with a femtosecond laser, should make it possible to better preserve corneal innervation and biomechanics. After a detailed review of the technique itself, we then focus on the scientific evidence for the safety and efficacy of SMILE and its current indications. Advantages of SMILE will be discussed in comparison to the conventional techniques, particularly concerning dry eye and the risk of corneal ectasia related to LASIK. Lastly, the current limitations of SMILE (indications, retreatment) are discussed, and future applications are considered regarding new improvements in the technique.

Abstract P3-14-08: Immediate breast reconstruction is highly accepted by breast cancer patients undergoing mastectomy when routinely offered- Recent experience of an Australian tertiary oncoplastic breast unit

Introduction:

Despite recommendations by breast cancer guidelines, that immediate breast reconstruction (IBR) should be offered to all breast cancer patients considered for mastectomy national IBR rates have been reported as low as 12% in Australia. We report our oncoplastic breast cancer unit experience on acceptance of IBR, where it is routinely offered for all the medical fit breast cancer patients.

Methods:

We retrospectively reviewed, prospectively collected data on IBR by 3 oncoplastic breast cancer surgeons from 1st of September 2014 to 31st of March 2016.Patients were considered to be unfit for IBR if they were American Society of Anasthesiologist (ASA) Score 4 or 5, have unstable psychiatric illness, inflammatory breast cancer or high metastatic cancer burden. All the patients who were fit for IBR were offered both prosthetic and autologous IBR options.

Results:

137 patients underwent mastectomy operation, of whom 27 were considered unfit for IBR. Of the remaining 110 patients, 84 (76%) accepted IBR. Of the patients who had IBR 64 (76%) had single stage prosthetic, 15 (18%) two stage prosthetic and 5 (6%) autologous reconstructions. Those who accepted IBR were younger compared to those who didn't have IBR (median age: 47 yrs vs. 67 yrs, p<0.001), and were more likely to be in current relationship (78.57% vs. 61.54%, p=0.06). All the three surgeons had high IBR acceptance rates (70.45%, 71.43%, 84.44%) and patient insurance status did not influence IBR acceptance rate (public 57% vs. private 65%, p=0.47). The majority of patients (25 of 26) who did not accept IBR stated that breast reconstruction was not important for their body image.

Conclusion:

Our recent data shows, in Australia, when routinely offered to breast cancer patients who are fit for reconstructive surgery by oncoplastic breast cancer surgeons, IBR is highly accepted. Younger patients and those who are in current relationship, were more likely to accept IBR, whereas, individual perception of insignificance of breast reconstruction for the body image was the main determinant of not accepting IBR.

Citation Format: Cheung DSM, Trinh L, Edirimanne S, Eslick G. Immediate breast reconstruction is highly accepted by breast cancer patients undergoing mastectomy when routinely offered- Recent experience of an Australian tertiary oncoplastic breast unit [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-14-08.

Pancreas volume and fat fraction in children with Type 1 diabetes

AIMS

People with Type 1 diabetes have smaller pancreases than healthy individuals. Several diseases causing pancreatic atrophy are associated with pancreatic steatosis, but pancreatic fat in Type 1 diabetes has not been measured. This cross-sectional study aimed to compare pancreas size and fat fraction in children with Type 1 diabetes and controls.

METHODS

The volume and fat fraction of the pancreases of 22 children with Type 1 diabetes and 29 controls were determined using magnetic resonance imaging.

RESULTS

Pancreas volume was 27% smaller in children with diabetes (median 34.9 cm(3) ) than in controls (47.8 cm(3) ; P < 0.001). Pancreas volume correlated positively with age in controls (P = 0.033), but not in children with diabetes (P = 0.649). Pancreas volume did not correlate with diabetes duration, but it did correlate positively with units of insulin/kg body weight/day (P = 0.048). A linear model of pancreas volume as influenced by age, body surface area and insulin units/kg body weight/day found that insulin dosage correlated with pancreas volume after controlling for both age and body surface area (P = 0.009). Pancreatic fat fraction was not significantly different between the two groups (1.34% vs. 1.57%; P = 0.891).

CONCLUSIONS

Our findings do not indicate that pancreatic atrophy in Type 1 diabetes is associated with an increased pancreatic fat fraction, unlike some other diseases featuring reduced pancreatic volume. We speculate that our results may support the hypotheses that much of pancreatic atrophy in Type 1 diabetes occurs before the clinical onset of the disease and that exogenous insulin administration decelerates pancreatic atrophy after diabetes onset.

An SPR based sensor for allergens detection

A simple, sensitive and label-free optical sensor method was developed for allergens analysis using α-casein as the biomarker for cow's milk detection, to be used directly in final rinse samples of cleaning in place systems (CIP) of food manufacturers. A Surface Plasmon Resonance (SPR) sensor chip consisting of four sensing arrays enabling the measurement of samples and control binding events simultaneously on the sensor surface was employed in this work. SPR offers several advantages in terms of label free detection, real time measurements and superior sensitivity when compared to ELISA based techniques. The gold sensor chip was used to immobilise α-casein-polyclonal antibody using EDC/NHS coupling procedure. The performance of the assay and the sensor was first optimised and characterised in pure buffer conditions giving a detection limit of 58ngmL^-1 as a direct binding assay. The assay sensitivity can be further improved by using sandwich assay format and amplified with nanoparticles. However, at this stage this is not required as the detection limit achieved exceeded the required allergens detection levels of 2µgmL^-1 for α-S1-casein. The sensor demonstrated good selectivity towards the α-casein as the target analyte and adequate recoveries from CIP final rinse wash samples. The sensor would be useful tool for monitoring allergen levels after cleaning procedures, providing additional data that may better inform upon wider food allergen risk management decision(s) that are made by food manufacturer. In particular, this sensor could potentially help validate or optimise cleaning practices for a given food manufacturing process.

Rapid Glucocorticoid Feedback Inhibition of ACTH Secretion Involves Ligand-Dependent Membrane Association of Glucocorticoid Receptors

The hypothesis that rapid glucocorticoid inhibition of pituitary ACTH secretion mediates a feedforward/feedback mechanism responsible for the hourly glucocorticoid pulsatility was tested in cultured pituitary cells. Perifusion with 30 pM CRH caused sustained the elevation of ACTH secretion. Superimposed corticosterone pulses inhibited CRH-stimulated ACTH release, depending on prior glucocorticoid clearance. When CRH perifusion started after 2 hours of glucocorticoid-free medium, corticosterone levels in the stress range (1 μM) caused a delayed (25 min) and prolonged inhibition of CRH-stimulated ACTH secretion, up to 60 minutes after corticosterone withdrawal. In contrast, after 6 hours of glucocorticoid-free medium, basal corticosterone levels inhibited CRH-stimulated ACTH within 5 minutes, after rapid recovery 5 minutes after corticosterone withdrawal. The latter effect was insensitive to actinomycin D but was prevented by the glucocorticoid receptor antagonist, RU486, suggesting nongenomic effects of the classical glucocorticoid receptor. In hypothalamic-derived 4B cells, 10 nM corticosterone increased immunoreactive glucocorticoid receptor content in membrane fractions, with association and clearance rates paralleling the effects on ACTH secretion from corticotrophs. Corticosterone did not affect CRH-stimulated calcium influx, but in AtT-20 cells, it had biphasic effects on CRH-stimulated Src phosphorylation, with early inhibition and late stimulation, suggesting a role for Src phosphorylation on the rapid glucocorticoid feedback. The data suggest that the nongenomic/membrane effects of classical GR mediate rapid and reversible glucocorticoid feedback inhibition at the pituitary corticotrophs downstream of calcium influx. The sensitivity and kinetics of these effects is consistent with the hypothesis that pituitary glucocorticoid feedback is part of the mechanism for adrenocortical ultradian pulse generation.

Bacillus anthracis cell wall peptidoglycan but not lethal or edema toxins produces changes consistent with disseminated intravascular coagulation in a rat model

BACKGROUND

Disseminated intravascular coagulation (DIC) appears to be important in the pathogenesis of Bacillus anthracis infection, but its causes are unclear. Although lethal toxin (LT) and edema toxin (ET) could contribute, B. anthracis cell wall peptidoglycan (PGN), not the toxins, stimulates inflammatory responses associated with DIC.

METHODS AND RESULTS

To better understand the pathogenesis of DIC during anthrax, we compared the effects of 24-hour infusions of PGN, LT, ET, or diluent (control) on coagulation measures 6, 24, or 48 hours after infusion initiation in 135 rats. No control recipient died. Lethality rates (approximately 30%) did not differ among PGN, LT, and ET recipients (P = .78). Thirty-three of 35 deaths (94%) occurred between 6 and 24 hours after the start of challenge. Among challenge components, PGN most consistently altered coagulation measures. Compared with control at 6 hours, PGN decreased platelet and fibrinogen levels and increased prothrombin and activated partial thromboplastin times and tissue factor, tissue factor pathway inhibitor, protein C, plasminogen activator inhibitor (PAI), and thrombin-antithrombin complex levels, whereas LT and ET only decreased the fibrinogen level or increased the PAI level (P ≤ .05). Nearly all effects associated with PGN infusion significantly differed from changes associated with toxin infusion (P ≤ .05 for all comparisons except for PAI level).

CONCLUSION

DIC during B. anthracis infection may be related more to components such as PGN than to LT or ET.

Evidence for helical structure in a tetramer of α2-8 sialic acid: unveiling a structural antigen

Characteristic H-bonding patterns define secondary structure in proteins and nucleic acids. We show that similar patterns apply for α2-8 sialic acid (SiA) in H(2)O and that H-bonds define its structure. A (15)N,(13)C α2-8 SiA tetramer, (SiA)(4), was used as a model system for the polymer. At 263 K, we detected intra-residue through-H-bond J couplings between (15)N and C8 for residues R-I-R-III of the tetramer, indicating H-bonds between the (15)N's and the O8's of these residues. Additional J couplings between the (15)N's and C2's of the adjacent residues confirm the putative H-bonds. NH groups showing this long-range correlation also experience slower (1)H/(2)H exchange. Additionally, detection of couplings between H7 and C2 for R-II and R-III implies that the conformations of the linkers between these residues are different than in the monomers. These structural elements are consistent with two left-handed helical models: 2 residues/turn (2(4) helix) and 4 residues/turn (1(4) helix). To discriminate between models, we resorted to (1)H,(1)H NOEs. The 2(4) helical model is in better agreement with the experimental data. We provide direct evidence of H-bonding for (SiA)(4) and show how H-bonds can be a determining factor for shaping its 3D structure.

Production, purification, and characterization of human alpha1 proteinase inhibitor from Aspergillus niger

Human alpha one proteinase inhibitor (alpha1-PI) was cloned and expressed in Aspergillus niger, filamentious fungus that can grow in defined media and can perform glycosylation. Submerged culture conditions were established using starch as carbon source, 30% dissolved oxygen concentration, pH 7.0 and 28 degrees C. Eight milligrams per liter of active alpha1-PI were secreted to the growth media in about 40 h. Controlling the protein proteolysis was found to be an important factor in the production. The effects of various carbon sources, pH and temperature on the production and stability of the protein were tested and the product was purified and characterized. Two molecular weights variants of the recombinant alpha1-PI were produced by the fungus; the difference is attributed to the glycosylated part of the molecule. The two glycoproteins were treated with PNGAse F and the released glycans were analyzed by HPAEC, MALDI/TOF-MS, NSI-MS(n), and GC-MS. The MALDI and NSI- full MS spectra of permethylated N-glycans revealed that the N-glycans of both variants contain a series of high-mannose type glycans with 5-20 hexose units. Monosaccharide analysis showed that these were composed of N-acetylglucos-amine, mannose, and galactose. Linkage analysis revealed that the galactosyl component was in the furanoic conformation, which was attaching in a terminal non-reducing position. The Galactofuranose-containing high-mannnose type N-glycans are typical structures, which recently have been found as part of several glycoproteins produced by Aspergillus niger.

Breast cancer patients stratification by microarray-based gene expression profiling from FFPET samples

e22041

Background: Microarrays have been used to monitor global genes expression and have aided the identification of novel biomarkers for patients stratification and drug response prediction . To date there has been limited application of microarray- based gene expression analysis to formalin fixed paraffin embedded tissues (FFPET). FFPE tissues are the most commonly available clinical samples with documented clinical information for retrospective clinical analysis. However, FFPET RNA has proven to be an obstacle for microarray analysis because of low yield and compromised RNA integrity. Methods: Using a novel RNA amplification method, Single Primer Isothermal Amplification (SPIA, NuGEN Inc, San Carlos, CA), we amplified FFPET RNA, hybridized amplified, and labeled cDNA onto Affymetrix HG U133plus2 GeneChips. Results: We found that SPIA amplification successfully overcomes the problems of poor quality of FFPET RNA, and produced informative biological data. Comparing the gene expression data from 5 different types of FFPET archival cancer samples (breast, lung, ovarian, colon, and melanoma), we demonstrated that gene expression signatures clearly distinguish the tissue of origin. Further, from an analysis of 91 FFPET samples comprised of ER+, HER2+, triple negative breast cancer patients, and normal breast tissue, we have identified a 103 gene signature that distinguishes the intrinsic sub-types of breast cancer. Finally, the accuracy of gene expression measured by microarray was verified by real time PCR quantitation of the ERBB2 gene, resulting in a significant correlation (R = 0.88). Conclusions: We have demonstrated the feasibility of global gene expression profiling using RNA extracted from FFPET and have shown that a gene expression signature can stratify patient samples into different subtypes of disease. This study paves the way to identify novel molecular biomarkers for disease stratification and therapy response from archival FFPET samples, leading to the goals of personalized medicine.

No significant financial relationships to disclose.

Expression of human alpha1-proteinase inhibitor in Aspergillus niger

Background

Human α₁-proteinase inhibitor (α₁-PI), also known as antitrypsin, is the most abundant serine protease inhibitor (serpin) in plasma. Its deficiency is associated with development of progressive, ultimately fatal emphysema. Currently in the United States, α₁-PI is available for replacement therapy as an FDA licensed plasma-derived (pd) product. However, the plasma source itself is limited; moreover, even with efficient viral inactivation steps used in manufacture of plasma products, the risk of contamination from emerging viruses may still exist. Therefore, recombinant α₁-PI (r-α₁-PI) could provide an attractive alternative. Although r-α₁-PI has been produced in several hosts, protein stability in vitro and rapid clearance from the circulation have been major issues, primarily due to absent or altered glycosylation.

Results

We have explored the possibility of expressing the gene for human α₁-PI in the filamentous fungus Aspergillus niger (A. niger), a system reported to be capable of providing more "mammalian-like" glycosylation patterns to secretable proteins than commonly used yeast hosts. Our expression strategy was based on fusion of α₁-PI with a strongly expressed, secreted leader protein (glucoamylase G2), separated by dibasic processing site (N-V-I-S-K-R) that provides in vivo cleavage. SDS-PAGE, Western blot, ELISA, and α₁-PI activity assays enabled us to select the transformant(s) secreting a biologically active glycosylated r-α₁-PI with yields of up to 12 mg/L. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis further confirmed that molecular mass of the r-α₁-PI was similar to that of the pd-α₁-PI. In vitro stability of the r-α₁-PI from A. niger was tested in comparison with pd-α₁-PI reference and non-glycosylated human r-α₁-PI from E. coli.

Conclusion

We examined the suitability of the filamentous fungus A. niger for the expression of the human gene for α₁-PI, a medium size glycoprotein of high therapeutic value. The heterologous expression of the human gene for α₁-PI in A. niger was successfully achieved to produce the secreted mature human r-α₁-PI in A. niger as a biologically active glycosylated protein with improved stability and with yields of up to 12 mg/L in shake-flask growth.

Pli maculaire compliquant la chirurgie du décollement de rétine

INTRODUCTION

The occurrence of a retinal fold after vitrectomy for retinal reattachment is not often described. In this case report, its treatment, prevention, and mechanism are discussed.

CASE REPORT

A 45-year-old pseudophakic woman experienced a superotemporal retinal detachment with macula-on and numerous retinal tears. The treatment consisted of a vitrectomy, perfluorocarbon injection, cryotherapy, and a complete fluid/gas exchange. Postoperative examination disclosed a retinal fold centered by the fovea. The treatment of this macular fold included the creation of a new detachment of the posterior pole by means of an injection of balanced saline solution into the subretinal space through a 39-gauge cannula, the injection of perfluorocarbon liquid to move the fold superiorly, endolaser at the inferior limit of the fold, and silicone oil injection. At the postoperative examination, the macula was flattened and the fold was near the superior temporal arcade.

DISCUSSION

The formation of a macular fold after vitrectomy was probably caused by the complete fluid/gas exchange, which displaced the subretinal fluid from the periphery to the posterior pole, detaching the macula. Tangential traction exerted by the presence of intravitreal gas and subretinal fluid might have stretched the retina and resulted in the formation of the fold. This mechanism is similar to the technique used in macular translocation surgery. To avoid this complication in macula-on retinal detachment, we suggest not using perfluorocarbon liquid systematically and replacing the complete fluid/gas exchange with a limited bubble of expansive gas combined with postoperative positioning.

Screen-less expanded bed column: new approach for the recovery and purification of a malaria transmission blocking vaccine candidate from Pichia pastoris

An experimental malaria transmission blocking vaccine antigen, Pfs25H, expressed and secreted from Pichia pastoris was recovered and purified using a screenless expanded bed column equipped with a rotating fluid distribution system. This column was able to accommodate feed stock, containing 30% biomass, at a flow rate of 300-400 cm/h without affecting column stability. This capability is three times higher than the capability of the expanded bed column currently in use, which is equipped with a perforated plate fluid distribution system; this design could accommodate biomass concentrations of only up to 10%. The screen-less design did not affect the binding capacity, purification level or process yield and, therefore, shorten the process. Purified Pfs25H of 6.4 g were recovered from 37 l of Pichia pastoris culture in one step.

Endostatin capture from Pichia pastoris culture in a fluidized bed. From on-chip process optimization to application

One of the characteristics of the methylothrophic yeast Pichia pastoris is its ability to grow to a very high cell density. Biomass concentrations of 300-400 g wet mass/l are common. It is therefore obvious that the recovery processes of extracellular proteins from this microorganism should take into account the effect of high biomass content. Separation by filtration and/or centrifugation is possible but these steps are cumbersome and can affect the protein recovery. The use of fluidized beds is attractive proteins capture option since it eliminates the biomass while capturing the desired protein. Zirconia-based resins possess unique properties which make them appropriate for processing high biomass concentrations in an expanded bed mode. The beads are particularly heavy (density is 3.2 g/ml) and small (75 microm) and therefore can accommodate high fluidization velocity and high mass transport. Specific operating conditions for effective capture of expressed protein have to be determined. This determination is generally time consuming and requires relatively large amount of feedstock for the lab trials. To avoid multiple chromatographic trials in columns, optimal conditions of adsorption and elution were determined by ProteinChip technology coupled with mass spectrometry. This technology involves flat chip surfaces functionalized as chromatographic beads where it is possible to adsorb and desorb proteins. Four different functional groups (strong anion-exchange, weak cation-exchange, hydrophobic and metal chelate) were tested and the retained proteins were analyzed directly by mass spectrometry. The weak cation-exchange group was chosen for further work. The Zirconia-based weak cation-exchange sorbent (CM HyperZ) was evaluated for binding capacity in a packed column and then for capturing endostatin from crude feed stock. Based on the previously determined conditions; 45 l of culture containing approximately 15 kg of biomass (wet mass) and 3 g endostatin were applied on an expanded bed at a flow-rate of 535 cm/h, yielding 80% of the endostatin and removing approximately 80% of foreign proteins.

Recovery of mouse endostatin produced by Pichia pastoris using expanded bed adsorption

Endostatin, a 20 KDa fragment of collagen XVIII, was shown to have an inhibitory effect on angiogenesis and can potentially be used as a tumor growth suppressor. To obtain the amount needed for testing, the protein was successfully cloned and expressed in Pichia pastoris. At the end of the fermentation process, the concentration of the endostatin in the culture was 50 mg per liter, accompanied by 400 gr per liter (wet weight) of biomass. Before the protein can be captured and purified on a packed bed of heparin-Sepharose, the biomass must be removed. Because of the high biomass concentration, conventional biomass removal techniques like centrifugation or filtration are inefficient and cumbersome. Therefore, the expanded-bed adsorption technique was chosen as an alternative approach. An efficient procedure for the initial recovery and purification of the endostatin was developed. The process utilized a cation- exchanger resin instead of a heparin-based affinity resin, because its dynamic capacity was higher, even though it was affected by the high linear flow on the expanded bed. After adjusting the conductivity, pH and biomass concentration, the complete broth was pumped directly on the expanded-bed matrix (Streamline SP XL). Though the yields of protein are similar, the expanded-bed approach is superior to the packed-bed method for several reasons. The expanded-bed process was shorter (only 8 hours compared to 16 hours for the packed bed), it is cheaper, and the product has higher specific activity (29% compared with 18%). Endostatin produced by the expanded-bed adsorption method showed the expected bioactivity and is currently being tested for its potential as a tumor suppressor.

Development of an Immunofluorometric, High-Capacity, Cell-Based Assay for the Measurement of Human Type I and Type II Interferons

We have developed a cell-based 96-well microtiter plate, high throughput assay for measuring both type I and type II interferon (IFN) activity on human cells. This assay makes use of a previously described IFN-specific reporter stably expressed in human HT 1080 cells. The induction of the reporter by IFN is determined by measuring the IFN-dependent expression of CD2 on the cell surface. The cytokine-induced expression of CD2 occurs within 48 h and is measured using a time-resolved fluorometric immunoassay. The limit of detection for type I IFN is.0.4 IU/ml. Interassay and intraassay coefficients of variation were 1.1% and 1.3% for the medium control (31 IU IFNb1b/ml), respectively. The limit of detection for type II IFN is.8 IU/ml, and the assay coefficients of variation are similar to those determined for type I IFNs. The level of sensitivity for this assay is comparable to other assays commonly used to measure IFN activity on cells. The current assay has an advantage over antiviral and antiproliferative assays, in that there is no requirement for the use of pathogenic virus or for determining viable cell numbers. The current assay is ideally suited for increasing sample screening and high-capacity automation, making it an excellent tool for drug discovery.

Design, synthesis, and in vitro biological activity of indole-based factor Xa inhibitors

A series of indole and carbazole based inhibitors of factor Xa (FXa) has been investigated. The most potent compound inhibits FXa with a Ki of 0.2 nM and has 900- and 750-fold selectivity over thrombin and trypsin, respectively.

Design, synthesis, and in vitro biological activity of benzimidazole based factor Xa inhibitors

Inhibitors based on the benzimidazole scaffold showed subnanomolar potency against Factor Xa with 500-1000-fold selectivity against thrombin and 50-100-fold selectivity against trypsin. The 2-substituent on the benzimidazole ring had a strong impact on the FXa inhibitory activity. Crystallography studies suggest that the 2-substituent may have a conformational effect favoring the extended binding conformation.

Design, synthesis, and activity of 2,6-diphenoxypyridine-derived factor Xa inhibitors

A novel series of 2,6-diphenoxypyridines has been designed to inhibit factor Xa, a serine protease strategically located in the coagulation cascade. The evolution from the photochemically unstable bisamidine (Z,Z)-BABCH to potent bisamidine compounds with a pyridine heterocycle as the core scaffold has been achieved. The most potent compound in the series, 6h, has a Ki for human factor Xa of 12 nM. The selectivity of 6h against bovine trypsin and human thrombin was greater than 90- and 1000-fold, respectively. Two proposed modes of binding of 6h to factor Xa are made based on the crystal structures of 6h by itself and of 6h bound to bovine trypsin.

Design, synthesis, and biological activity of novel purine and bicyclic pyrimidine factor Xa inhibitors

The synthesis of amidinoaryloxy 9-benzyl-8-methyl-9H-purine, 7,8-dihydropteridine-6(5H)-one and 5,7-dihydropyrimido[4,5-b][1,4]oxazine-6-one inhibitors of Factor Xa is described. These compounds show nanomolar potency against FXa and maintain high selectivity over thrombin and trypsin.

Solid-phase synthesis of N-substituted amidinophenoxy pyridines as factor XA inhibitors

An arylamidine linker has been employed for the solid-phase synthesis of N-substituted amidinoaryloxypyridine analogs 2 via nucleophilic substitution on a fluoropyridyl template. Two novel N-substituted amidinoaryloxypyridine derivatives 2a and 2b were discovered via this approach.