Improving non-invasive hemoglobin measurement accuracy using nonparametric models.

Uncontrolled hemorrhage is a leading cause of preventable death among patients with trauma. Early recognition of hemorrhage can aid in the decision to administer blood transfusion and improve patient outcomes. To provide real-time measurement and continuous monitoring of hemoglobin concentration, the non-invasive and continuous hemoglobin (SpHb) measurement device has drawn extensive attention in clinical practice. However, the accuracy of such a device varies in different scenarios, so the use is not yet widely accepted. This article focuses on using statistical nonparametric models to improve the accuracy of SpHb measurement device by considering measurement bias among instantaneous measurements and individual evolution trends. In the proposed method, the robust locally estimated scatterplot smoothing (LOESS) method and the Kernel regression model are considered to address those issues. Overall performance of the proposed method was evaluated by cross-validation, which showed a substantial improvement in accuracy with an 11.3% reduction of standard deviation, 23.7% reduction of mean absolute error, and 28% reduction of mean absolute percentage error compared to the original measurements. The effects of patient demographics and initial medical condition were analyzed and deemed to not have a significant effect on accuracy. Because of its high accuracy, the proposed method is highly promising to be considered to support transfusion decision-making and continuous monitoring of hemoglobin concentration. The method also has promise for similar advancement of other diagnostic devices in healthcare.

Non-invasive Hemoglobin Measurement Predictive Analytics with Missing Data and Accuracy Improvement Using Gaussian Process and Functional Regression Model.

Recent use of noninvasive and continuous hemoglobin (SpHb) concentration monitor has emerged as an alternative to invasive laboratory-based hematological analysis. Unlike delayed laboratory based measures of hemoglobin (HgB), SpHb monitors can provide real-time information about the HgB levels. Real-time SpHb measurements will offer healthcare providers with warnings and early detections of abnormal health status, e.g., hemorrhagic shock, anemia, and thus support therapeutic decision-making, as well as help save lives. However, the finger-worn CO-Oximeter sensors used in SpHb monitors often get detached or have to be removed, which causes missing data in the continuous SpHb measurements. Missing data among SpHb measurements reduce the trust in the accuracy of the device, influence the effectiveness of hemorrhage interventions and future HgB predictions. A model with imputation and prediction method is investigated to deal with missing values and improve prediction accuracy. The Gaussian process and functional regression methods are proposed to impute missing SpHb data and make predictions on laboratory-based HgB measurements. Within the proposed method, multiple choices of sub-models are considered. The proposed method shows a significant improvement in accuracy based on a real-data study. Proposed method shows superior performance with the real data, within the proposed framework, different choices of sub-models are discussed and the usage recommendation is provided accordingly. The modeling framework can be extended to other application scenarios with missing values.

Mild Alkaline Pretreatment of Rice Straw as a Feedstock in Microbial Fuel Cells for Generation of Bioelectricity.

The dependency on non-renewable fossil fuels as an energy source has drastically increased global temperatures. Their continuous use poses a great threat to the existing energy reserves. Therefore, the energy sector has taken a turn toward developing eco-friendly, sustainable energy generation by using sustainable lignocellulosic wastes, such as rice straw (RS). For lignocellulosic waste to be utilized as an efficient energy source, it needs to be broken down into less complex forms by pretreatment processes, such as alkaline pretreatment using NaOH. Varied NaOH concentrations (0.5%,1.0%,1.5%,2%) for alkaline pretreatment of RS were used for the holocellulose generation. Amongst the four NaOH concentrations tested, RS-1.5% exhibited higher holocellulose generation of 80.1%, whereas 0.5%, 1 5 and 2% pointed 71.9%, 73.8%, and 78.5% holocellulose generation, respectively. Further, microbial fuel cells (MFCs) were tested for voltage generation by utilizing holocellulose generated from untreated (RS-0%) and mildly alkaline pretreated RS (RS-1.5%) as a feedstock. The MFC voltage and maximum power generation using RS-0% were 194 mV and 167 mW/m2, respectively. With RS-1.5%, the voltage and maximum power generation were 556 mV and 583 mW/m2, respectively. The power density of RS-1.5% was three-fold higher than that of RS-0%. The increase in MFC power generation suggests that alkaline pretreatment plays a crucial role in enhancing the overall performance.

Measuring Sensitivity and Precision of Real-Time Location Systems (RTLS): Definition, Protocol and Demonstration for Clinical Relevance.

The ability of a Real Time Location System (RTLS) to provide correct information in a clinical environment is an important consideration in evaluating the effectiveness of the technology. While past efforts describe how well the technology performed in a lab environment, the performance of such technology has not been specifically defined or evaluated in a practice setting involving workflow and movement. Clinical environments pose complexity owing to various layouts and various movements. Further, RTL systems are not equipped to provide true negative information (where an entity is not located). Hence, this study defined sensitivity and precision in this context, and developed a simulation protocol to serve as a systematic testing framework using actors in a clinical environment. The protocol was used to measure the sensitivity and precision of an RTL system in the emergency department space of a quaternary care medical center. The overall sensitivity and precision were determined to be 84 and 93% respectively. These varied for patient rooms, staff area, hallway and other rooms.

Correction to: Biomethanol Production from Methane by Immobilized Co-cultures of Methanotrophs.

[This corrects the article DOI: 10.1007/s12088-020-00883-6.].

Biomethanol Production from Methane by Immobilized Co-cultures of Methanotrophs.

Methanol production by co-culture of methanotrophs Methylocystis bryophila and Methyloferula stellata was examined from methane, a greenhouse gas. Co-culture exhibited higher methanol yield of 4.72 mM at optimum ratio of M. bryophila and M. stellata (3:2) compared to individual cultures. The immobilized co-culture within polyvinyl alcohol (PVA) showed relative efficiency of 90.1% for methanol production at polymer concentration of 10% (v/v). The immobilized co-culture cells within PVA resulted in higher bioprocess stability over free cells at different pH, and temperatures. Free and encapsulated co-cultures showed maximum methanol production of 4.81 and 5.37 mM under optimum conditions, respectively. After five cycles of reusage under batch conditions, free and encapsulated co-cultures retained methanol production efficiency of 23.8 and 61.9%, respectively. The present investigation successfully revealed the useful influence of co-culture on the methanol production over pure culture. Further, encapsulation within the polymeric matrix proved to be a better approach for the enhanced stability of the bioprocess.

Single-stranded DNA Binding by the Helix-Hairpin-Helix Domain of XPF Protein Contributes to the Substrate Specificity of the ERCC1-XPF Protein Complex.

The nucleotide excision repair protein complex ERCC1-XPF is required for incision of DNA upstream of DNA damage. Functional studies have provided insights into the binding of ERCC1-XPF to various DNA substrates. However, because no structure for the ERCC1-XPF-DNA complex has been determined, the mechanism of substrate recognition remains elusive. Here we biochemically characterize the substrate preferences of the helix-hairpin-helix (HhH) domains of XPF and ERCC-XPF and show that the binding to single-stranded DNA (ssDNA)/dsDNA junctions is dependent on joint binding to the DNA binding domain of ERCC1 and XPF. We reveal that the homodimeric XPF is able to bind various ssDNA sequences but with a clear preference for guanine-containing substrates. NMR titration experiments and in vitro DNA binding assays also show that, within the heterodimeric ERCC1-XPF complex, XPF specifically recognizes ssDNA. On the other hand, the HhH domain of ERCC1 preferentially binds dsDNA through the hairpin region. The two separate non-overlapping DNA binding domains in the ERCC1-XPF heterodimer jointly bind to an ssDNA/dsDNA substrate and, thereby, at least partially dictate the incision position during damage removal. Based on structural models, NMR titrations, DNA-binding studies, site-directed mutagenesis, charge distribution, and sequence conservation, we propose that the HhH domain of ERCC1 binds to dsDNA upstream of the damage, and XPF binds to the non-damaged strand within a repair bubble.

In-vitro and in-silico analysis and antitumor studies of novel Cu(II) and V(V) complexes of N-p-Tolylbenzohydroxamic acid.

Copper(L2Cu) and vanadium(L2VOCl) complexes of N-p-tolylbenzohydroxamic acid (LH) ligand have been investigated for DNA binding efficacy by multiple analytical, spectral, and computational techniques. The results revealed that complexes as groove binders as evidenced by UV absorption. Fluorescence studies including displacement assay using classical intercalator ethidium bromide as fluorescent probe also confirmed as groove binders. The viscometric analysis too supports the inferences as strong groove binders for both the complexes. Molecular docking too exposed DNA as a target to the complexes which precisely binds L2Cu, in the minor groove region while L2VOCl in major groove region. Molecular dynamic simulation performed on L2Cu complex revealing the interaction of complex with DNA within 20 ns time. The complex stacked into the nitrogen bases of oligonucleotides and the bonding features were intrinsically preserved for longer simulation times. In-vitro cytotoxicity study was undertaken employing MTT assay against the breast cancer cell line (MCF-7). Potential cytotoxic activities were observed for L2Cu and L2VOCl complexes with IC50 values of showing 71 % and 74 % of inhibition respectively.

Quantifying the Impact of Resuscitation-Team Activation in Hospital Emergency Departments.

Hospital emergency department (ED) operations are affected when critically ill or injured patients arrive. Such events often lead to the initiation of specific protocols, referred to as Resuscitation-team Activation (RA), in the ED of Mayo Clinic, Rochester, MN where this study was conducted. RA events lead to the diversion of resources from other patients in the ED to provide care to critically ill patients; therefore, it has an impact on the entire ED system. This paper presents a data-driven and flexible statistical learning model to quantify the impact of RA on the ED. The model learns the pattern of operations in the ED from historical patient arrival and departure timestamps and quantifies the impact of RA by measuring the deviation of the departure of patients during RA from normal processes. The proposed method significantly outperforms baseline methods based on measuring the average time patients spend in the ED.

Tyr320 is a molecular determinant of the catalytic activity of ß-glucosidase from Neosartorya fischeri.

ß-Glucosidases (BGL) are key members of the cellulase enzyme complex that determine efficiency of lignocellulosic biomass degradation, which have shown great functional importance to many biotechnological systems. A previous reported BGL from Neosartorya fischeri (NfBGL) showed much higher activity than other BGLs. Screening the important residues based on sequence alignment, analyzing a homology model, and subsequent alteration of individually screened residues by site-directed mutagenesis were carried out to investigate the molecular determinants of the enzyme's high catalytic efficiency. Tyr320, located in the wild-type NfBGL substrate-binding pocket was identified as crucial to the catalytic function of NfBGL. The replacement of Tyr320 with aromatic amino acids did not significantly alter the catalytic efficiency towards p-nitrophenyl ß-d-glucopyranoside (pNPG). However, mutants with charged and hydrophilic amino acids showed almost no activity towards pNPG. Computational studies suggested that an aromatic acid is required at position 320 in NfBGL to stabilize the enzyme-substrate complex formation. This knowledge on the mechanism of action of the molecular determinants can also help rational protein engineering of BGLs.

Analysis of the XPA and ssDNA-binding surfaces on the central domain of human ERCC1 reveals evidence for subfunctionalization.

Human ERCC1/XPF is a structure-specific endonuclease involved in multiple DNA repair pathways. We present the solution structure of the non-catalytic ERCC1 central domain. Although this domain shows structural homology with the catalytically active XPF nuclease domain, functional investigation reveals a completely distinct function for the ERCC1 central domain by performing interactions with both XPA and single-stranded DNA. These interactions are non-competitive and can occur simultaneously through distinct interaction surfaces. Interestingly, the XPA binding by ERCC1 and the catalytic function of XPF are dependent on a structurally homologous region of the two proteins. Although these regions are strictly conserved in each protein family, amino acid composition and surface characteristics are distinct. We discuss the possibility that after XPF gene duplication, the redundant ERCC1 central domain acquired novel functions, thereby increasing the fidelity of eukaryotic DNA repair.

Improving Accuracy of Noninvasive Hemoglobin Monitors: A Functional Regression Model for Streaming SpHb Data.

OBJECTIVE: The purpose of this paper is to develop a method for improving the accuracy of SpHb monitors, which are noninvasive hemoglobin monitoring tools, leading to better critical care protocols in trauma care. METHODS: The proposed method is based on fitting smooth spline functions to SpHb measurements collected over a time window and then using a functional regression model to predict the true HgB value for the end of the time window. RESULTS: The accuracy of the proposed method is compared to traditional methods. The mean absolute error between the raw SpHb measurements and the gold standard hemoglobin measurements was 1.26 g/Dl. The proposed method reduced the mean absolute error to 1.08 g/Dl. [1] Conclusion: Fitting a smooth function to SpHb measurements improves the accuracy of Hgb predictions. SIGNIFICANCE: Accurate prediction of current and future HgB levels can lead to sophisticated decision models that determine the optimal timing and amount of blood product transfusions.

Bioelectrochemical Detoxification of Phenolic Compounds during Enzymatic Pre-Treatment of Rice Straw.

The use of lignocellulosic biomass such as rice straw can help subsidize the cost of producing value-added chemicals. However, inhibitory compounds, such as phenolics, produced during the pre-treatment of biomass, hamper the saccharification process. Laccase and electrochemical stimuli are both well known to reduce phenolic compounds. Therefore, in this study, we implemented a bioelectrochemical detoxification system (BEDS), a consolidated electrochemical and enzymatic process involving laccase, to enhance the detoxification of phenolics, and thus achieve a higher saccharification efficiency. Saccharification of pretreated rice straw using BEDS at 1.5 V showed 90% phenolic reduction (Phr), thereby resulting in a maximum saccharification yield of 85%. In addition, the specific power consumption when using BEDS (2.2 W/Kg Phr) was noted to be 24% lower than by the electrochemical process alone (2.89 W/kg Phr). To the best of our knowledge, this is the first study to implement BEDS for reduction of phenolic compounds in pretreated biomass.

The HhH domain of the human DNA repair protein XPF forms stable homodimers.

The human XPF-ERCC1 protein complex plays an essential role in nucleotide excision repair by catalysing positioned nicking of a DNA strand at the 5' side of the damage. We have recently solved the structure of the heterodimeric complex of the C-terminal domains of XPF and ERCC1 (Tripsianes et al., Structure 2005;13:1849-1858). We found that this complex comprises a pseudo twofold symmetry axis and that the helix-hairpin-helix motif of ERCC1 is required for DNA binding, whereas the corresponding domain of XPF is functioning as a scaffold for complex formation with ERCC1. Despite the functional importance of heterodimerization, the C-terminal domain of XPF can also form homodimers in vitro. We here compare the stabilities of homodimeric and heterodimeric complexes of the C-terminal domains of XPF and ERCC1. The higher stability of the XPF HhH complexes under various experimental conditions, determined using CD and NMR spectroscopy and mass spectrometry, is well explained by the structural differences that exist between the HhH domains of the two complexes. The XPF HhH homodimer has a larger interaction interface, aromatic stacking interactions, and additional hydrogen bond contacts as compared to the XPF/ERCC1 HhH complex, which accounts for its higher stability.

Studying the in Silico Effect of Ellagic Acid on HIF-2α to Improve Efficacy of Anticancer Therapy.

The hypoxic tumor microenvironment is one of the major causes of the enhanced chemoresistant and radioresistant behavior of cancer cells. Therefore, the hypoxia-induced factor (HIF) pathway can be endorsed, for not only the malignant phenotype of the cells, but also its metastatic potential. Many drugs targeting the HIF pathways have failed in the clinical setting to demonstrate therapeutic efficacy. Such failures occur due to lack of specificity or redundancy in the complexity of tumor signaling/metabolism that can overcome the inhibitory effects. Another important factor is the letdown of the compound that can be accredited to lack of patient selection in the trials. Although many clinical trials have evaluated the efficacy of anticancer therapeutics and examined their effects on HIF levels, patients were not selected based on their HIF expression levels. If patients do not have elevated levels of HIF, then the therapeutics that target the HIF pathway may be less effective. In the present work, we have targeted HIF-2α of the HIF pathway. Ellagic acid (EA), a well-known anticancer compound and radiosensitizer, is used to inhibit the activity of HIF-2α. Our results show a very unique binding of EA with HIF-2α. Such new agents should be used in combination therapy and will hopefully overcome the resistance that may develop during initial treatment if the patient is identified to have enhanced expression of HIF-2α. Molecular dynamics studies followed solvation free energy calculations (molecular mechanics Poisson-Boltzmann surface area) for understanding the binding stability and per residue contribution. Our in silico data look promising and EA should be studied more in in vitro and in vivo for further analysis of its efficacy.

Synthesis, characterization and nucleic acid binding studies of mononuclear copper(II) complexes derived from azo containing O, O donor ligands.

Azo linked salicyldehyde and a new 2-hydroxy acetophenone based ligands (HL1 and HL2) with their copper(II) complexes [Cu(L1)2] (1) and [Cu(L2)2] (2) were synthesized and characterized by spectroscopic methods such as 1H, 13C NMR, UV-Vis spectroscopy and elemental analyses. Calculation based on Density Functional Theory (DFT), have been performed to obtain optimized structures. Binding studies of these copper (II) complexes with calf thymus DNA (ct-DNA) and torula yeast RNA (t-RNA) were analyzed by absorption spectra, emission spectra and Viscosity studies and Molecular Docking techniques. The absorption spectral study indicated that the copper(II) complexes of 1 and 2 had intrinsic binding constants with DNA or RNA in the range of 7.6 ± 0.2 × 103 M-1 or 6.5 ± 0.3 × 103M-1 and 5.7 ± 0.4 × 104 M-1 or 1.8 ± 0.5 × 103 M-1 respectively. The synthesized compounds and nucleic acids were simulated by molecular docking to explore more details mode of interaction of the complexes and their orientations in the active site of the receptor.

A Mouse Model of Creatine Transporter Deficiency Reveals Impaired Motor Function and Muscle Energy Metabolism.

Creatine serves as fast energy buffer in organs of high-energy demand such as brain and skeletal muscle. L-Arginine:glycine amidinotransferase (AGAT) and guanidinoacetate N-methyltransferase are responsible for endogenous creatine synthesis. Subsequent uptake into target organs like skeletal muscle, heart and brain is mediated by the creatine transporter (CT1, SLC6A8). Creatine deficiency syndromes are caused by defects of endogenous creatine synthesis or transport and are mainly characterized by intellectual disability, behavioral abnormalities, poorly developed muscle mass, and in some cases also muscle weakness. CT1-deficiency is estimated to be among the most common causes of X-linked intellectual disability and therefore the brain phenotype was the main focus of recent research. Unfortunately, very limited data concerning muscle creatine levels and functions are available from patients with CT1 deficiency. Furthermore, different CT1-deficient mouse models yielded conflicting results and detailed analyses of their muscular phenotype are lacking. Here, we report the generation of a novel CT1-deficient mouse model and characterized the effects of creatine depletion in skeletal muscle. HPLC-analysis showed strongly reduced total creatine levels in skeletal muscle and heart. MR-spectroscopy revealed an almost complete absence of phosphocreatine in skeletal muscle. Increased AGAT expression in skeletal muscle was not sufficient to compensate for insufficient creatine transport. CT1-deficient mice displayed profound impairment of skeletal muscle function and morphology (i.e., reduced strength, reduced endurance, and muscle atrophy). Furthermore, severely altered energy homeostasis was evident on magnetic resonance spectroscopy. Strongly reduced phosphocreatine resulted in decreased ATP/Pi levels despite an increased inorganic phosphate to ATP flux. Concerning glucose metabolism, we show increased glucose transporter type 4 expression in muscle and improved glucose clearance in CT1-deficient mice. These metabolic changes were associated with activation of AMP-activated protein kinase - a central regulator of energy homeostasis. In summary, creatine transporter deficiency resulted in a severe muscle weakness and atrophy despite different compensatory mechanisms.

Physiological and Pathological Brain Activation in the Anesthetized Rat Produces Hemodynamic-Dependent Cortical Temperature Increases That Can Confound the BOLD fMRI Signal.

Anesthetized rodent models are ubiquitous in pre-clinical neuroimaging studies. However, because the associated cerebral morphology and experimental methodology results in a profound negative brain-core temperature differential, cerebral temperature changes during functional activation are likely to be principally driven by local inflow of fresh, core-temperature, blood. This presents a confound to the interpretation of blood-oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) data acquired from such models, since this signal is also critically temperature-dependent. Nevertheless, previous investigation on the subject is surprisingly sparse. Here, we address this issue through use of a novel multi-modal methodology in the urethane anesthetized rat. We reveal that sensory stimulation, hypercapnia and recurrent acute seizures induce significant increases in cortical temperature that are preferentially correlated to changes in total hemoglobin concentration (Hbt), relative to cerebral blood flow and oxidative metabolism. Furthermore, using a phantom-based evaluation of the effect of such temperature changes on the BOLD fMRI signal, we demonstrate a robust inverse relationship between both variables. These findings suggest that temperature increases, due to functional hyperemia, should be accounted for to ensure accurate interpretation of BOLD fMRI signals in pre-clinical neuroimaging studies.

Decreased mitochondrial respiration in aneurysmal aortas of Fibulin-4 mutant mice is linked to PGC1A regulation.

Aim: Thoracic aortic aneurysms are a life-threatening condition often diagnosed too late. To discover novel robust biomarkers, we aimed to better understand the molecular mechanisms underlying aneurysm formation. Methods and results: In Fibulin-4R/R mice, the extracellular matrix protein Fibulin-4 is 4-fold reduced, resulting in progressive ascending aneurysm formation and early death around 3 months of age. We performed proteomics and genomics studies on Fibulin-4R/R mouse aortas. Intriguingly, we observed alterations in mitochondrial protein composition in Fibulin-4R/R aortas. Consistently, functional studies in Fibulin-4R/R vascular smooth muscle cells (VSMCs) revealed lower oxygen consumption rates, but increased acidification rates. Yet, mitochondria in Fibulin-4R/R VSMCs showed no aberrant cytoplasmic localization. We found similar reduced mitochondrial respiration in Tgfbr-1M318R/+ VSMCs, a mouse model for Loeys-Dietz syndrome (LDS). Interestingly, also human fibroblasts from Marfan (FBN1) and LDS (TGFBR2 and SMAD3) patients showed lower oxygen consumption. While individual mitochondrial Complexes I-V activities were unaltered in Fibulin-4R/R heart and muscle, these tissues showed similar decreased oxygen consumption. Furthermore, aortas of aneurysmal Fibulin-4R/R mice displayed increased reactive oxygen species (ROS) levels. Consistent with these findings, gene expression analyses revealed dysregulation of metabolic pathways. Accordingly, blood ketone levels of Fibulin-4R/R mice were reduced and liver fatty acids were decreased, while liver glycogen was increased, indicating dysregulated metabolism at the organismal level. As predicted by gene expression analysis, the activity of PGC1α, a key regulator between mitochondrial function and organismal metabolism, was downregulated in Fibulin-4R/R VSMCs. Increased TGFß reduced PGC1α levels, indicating involvement of TGFß signalling in PGC1α regulation. Activation of PGC1α restored the decreased oxygen consumption in Fibulin-4R/R VSMCs and improved their reduced growth potential, emphasizing the importance of this key regulator. Conclusion: Our data indicate altered mitochondrial function and metabolic dysregulation, leading to increased ROS levels and altered energy production, as a novel mechanism, which may contribute to thoracic aortic aneurysm formation.

The structure of the human ERCC1/XPF interaction domains reveals a complementary role for the two proteins in nucleotide excision repair.

The human ERCC1/XPF complex is a structure-specific endonuclease with defined polarity that participates in multiple DNA repair pathways. We report the heterodimeric structure of the C-terminal domains of both proteins responsible for ERCC1/XPF complex formation. Both domains exhibit the double helix-hairpin-helix motif (HhH)2, and they are related by a pseudo-2-fold symmetry axis. In the XPF domain, the hairpin of the second motif is replaced by a short turn. The ERCC1 domain folds properly only in the presence of the XPF domain, which implies a role for XPF as a scaffold for the folding of ERCC1. The intersubunit interactions are largely hydrophobic in nature. NMR titration data show that only the ERCC1 domain of the ERCC1/XPF complex is involved in DNA binding. On the basis of these findings, we propose a model for the targeting of XPF nuclease via ERCC1-mediated interactions in the context of nucleotide excision repair.