PCT Measurements Research Articles

Deep learning-based pseudo-CT synthesis from zero echo time MR sequences of the pelvis

ObjectivesTo generate pseudo-CT (pCT) images of the pelvis from zero echo time (ZTE) MR sequences and compare them to conventional CT.MethodsNinety-one patients were prospectively scanned with CT and MRI including ZTE sequences of the pelvis. Eleven ZTE image volumes were excluded due to implants and severe B1 field inhomogeneity. Out of the 80 data sets, 60 were used to train and update a deep learning (DL) model for pCT image synthesis from ZTE sequences while the remaining 20 cases were selected as an evaluation cohort. CT and pCT images were assessed qualitatively and quantitatively by two readers.ResultsMean pCT ratings of qualitative parameters were good to perfect (2–3 on a 4-point scale). Overall intermodality agreement between CT and pCT was good (ICC = 0.88 (95% CI: 0.85–0.90); p < 0.001) with excellent interreader agreements for pCT (ICC = 0.91 (95% CI: 0.88–0.93); p < 0.001). Most geometrical measurements did not show any significant difference between CT and pCT measurements (p > 0.05) with the exception of transverse pelvic diameter measurements and lateral center-edge angle measurements (p = 0.001 and p = 0.002, respectively). Image quality and tissue differentiation in CT and pCT were similar without significant differences between CT and pCT CNRs (all p > 0.05).ConclusionsUsing a DL-based algorithm, it is possible to synthesize pCT images of the pelvis from ZTE sequences. The pCT images showed high bone depiction quality and accurate geometrical measurements compared to conventional CT.Critical relevance statementpCT images generated from MR sequences allow for high accuracy in evaluating bone without the need for radiation exposure. Radiological applications are broad and include assessment of inflammatory and degenerative bone disease or preoperative planning studies.Key PointspCT, based on DL-reconstructed ZTE MR images, may be comparable with true CT images.Overall, the intermodality agreement between CT and pCT was good with excellent interreader agreements for pCT.Geometrical measurements and tissue differentiation were similar in CT and pCT images.Graphical

Proton CT on biological phantoms for x-ray CT calibration in proton treatment planning

Objective. To present and characterize a novel method for x-ray computed tomography (xCT) calibration in proton treatment planning, based on proton CT (pCT) measurements on biological phantoms. Approach. A pCT apparatus was used to perform direct measurements of 3D stopping power relative to water (SPR) maps on stabilized, biological phantoms. Two single-energy xCT calibration curves—i.e. tissue substitutes and stoichiometric—were compared to pCT data. Moreover, a new calibration method based on these data was proposed, and verified against intra- and inter-species variability, dependence on stabilization, beam-hardening conditions, and analysis procedures. Main results. Biological phantoms were verified to be stable in time, with a dependence on temperature conditions, especially in the fat region: (−2.5 土 0.5) HU °C−1. The pCT measurements were compared with standard xCT calibrations, revealing an average SPR discrepancy within ±1.60% for both fat and muscle regions. In the bone region the xCT calibrations overestimated the pCT-measured SPR of the phantom, with a maximum discrepancy of about +3%. As a result, a new cross-calibration curve was directly extracted from the pCT data. Overall, the SPR uncertainty margin associated with this curve was below 3%; fluctuations in the uncertainty values were observed across the HU range. Cross-calibration curves obtained with phantoms made of different animal species and anatomical parts were reproducible with SPR discrepancies within 3%. Moreover, the stabilization procedure did not affect the resulting curve within a 2.2% SPR deviation. Finally, the cross-calibration curve was affected by the beam-hardening conditions on xCTs, especially in the bone region, while dependencies below 2% resulted from the image registration procedure. Significance. Our results showed that pCT measurements on biological phantoms may provide an accurate method for the verification of current xCT calibrations and may represent a tool for the implementation of a new calibration method for proton treatment planning.

Development of Ti-Zr-Mn based AB2 type metal hydrides alloys for an 865 bar two-stage hydrogen compressor

This study reports the development of a new Ti-Zr-Mn-based AB2 type hydrogen storage alloys for a two-stage metal hydride hydrogen compressor (MHHC). The hydrogen storage alloys are designed to compress hydrogen from 35 to 865 bar within a temperature difference of 115 °C. High-pressure PCT measurements up to 700 bar were carried out to test the performance of the alloys. The alloys' hysteresis and the plateau slope were reduced by optimizing the composition. The introduction of fugacity correction into the Van't hoff equation reduces the deviation between calculation and actual pressure to 24 bar at a pressure above 350 bar. A precise relation between the Ti/Zr ratio and the desorption pressure is described and helps make a correct design of the alloy composition. The designed alloy shows looses less than 1% of the capacity over 3000 full cycles. The desorption plateau pressure of the alloy is constant within 92% during the whole cycling process. A 2 stages compressor working with two types of alloys offers compression with a temperature range between -20 and 95 °C for the refueling hydrogen vehicles up to 865 bar.

Segmentation Errors and Off-Center Artifacts in SS-OCT: Insight from a Population-Based Imaging Study

Purpose To evaluate the frequency and associated factors of artifacts in swept-source optical coherence tomography (SS-OCT) imaging. Methods This was a population-based cross-sectional study. Individuals aged 35 years or older, residing in the Yuexiu district of Guangzhou, China, were recruited by random cluster sampling. Nearly half of the participants were randomly selected for SS-OCT imaging centered on the optic nerve head. Six types of artifacts in the peripapillary choroidal layer and retinal nerve fiber layer (RNFL) were graded and identified. Univariate and multivariate logistic regression analyses were used to investigate the association between the presence of artifacts and clinical characteristics. Results Out of the 616 eligible individuals who underwent SS-OCT imaging, 18.3% and 13.6% of subjects exhibited at least one artifact in peripapillary RNFL (pRNFL) and peripapillary choroidal thickness (pCT) measurements, respectively, with posterior segmentation error and off-center artifact ranked as the most common artifacts. The presence of artifacts was significantly associated with age (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.01–1.06; p = .003), refractive error (OR, 0.80; 95% CI, 0.71–0.89; p < .001), and signal strength (OR, 0.95; 95% CI, 0.90–0.997; p = .039) in pRNFL thickness measurement. Similarly, the presence of artifacts in pCT measurement was significantly associated with age (OR, 1.05; 95% CI, 1.03–1.08; p < .001), and refractive error (OR, 0.76; 95% CI, 0.68–0.86; p < .001). Conclusion Nearly one-fifth of the eyes were noted with at least one artifact in the population-scale SS-OCT study. Age was a risk factor for the presence of artifacts and should be considered in clinical settings.

Experimental comparison of relative stopping power evaluation between proton CT and x-ray CT for pre-clinical proton irradiation studies of small animals

Objective. Proton therapy experiments in small animals are useful not only for pre-clinical and translational studies, but also for the development of advanced technologies for high-precision proton therapy. While treatment planning for proton therapy is currently based on the stopping power of protons relative to water (i.e. the relative stopping power (RSP)), estimated by converting the CT number into RSP (Hounsfield unit (HU)-RSP conversion) in reconstructed x-ray computed tomography (XCT) images, the HU-RSP conversion causes uncertainties in RSP, which affect the accuracy of dose simulation in patients. Proton computed tomography (pCT) has attracted a great deal of attention due to its potential to reduce RSP uncertainties in clinical treatment planning. However, as the proton energies for irradiating small animals are much lower than those used clinically, the energy dependence of RSP may negatively affect pCT-based RSP evaluation. Here, we explored whether the low-energy pCT approach provided more accurate RSPs when planning proton therapy treatment for small animals. Approach. We evaluated the RSPs of 10 water- and tissue-equivalent materials with known constituent elements based on pCT measurements conducted at 73.6 MeV, then compared them with XCT-based and calculated RSPs to investigate energy dependence and achieve more accurate RSPs for treatment planning in small animals. Main results. Despite the low proton energy, the pCT approach for RSP evaluation yields a smaller root mean square deviation (1.9%) of RSP from the theoretical prediction, compared to conventional HU-RSP conversion with XCT (6.1%). Significance. Low-energy pCT is expected to improve the accuracy of proton therapy treatment planning in pre-clinical studies of small animals if the RSP variation that can be attributed to energy dependence is identical to the variation in the clinical proton energy region.

Procalcitonin-Guided Antibiotic Prescription in Patients With COVID-19: A Multicenter Observational Cohort Study

Despite the low rate of bacterial coinfection, antibiotics are very commonly prescribed in hospitalized patients with COVID-19. Does the use of a procalcitonin (PCT)-guided antibiotic protocol safely reduce the use of antibiotics in patients with a COVID-19 infection? In this multicenter cohort, three groups of patients with COVID-19 were compared in terms of antibiotic consumption, namely one group treated based on a PCT-algorithm in one hospital (n= 216) and two control groups, consisting of patients from the same hospital (n= 57) and of patients from three similar hospitals (n= 486) without PCT measurements during the same period. The primary end point was antibiotic prescription in the first week of admission. Antibiotic prescription during the first 7days was 26.8%in the PCT group, 43.9%in the non-PCT group in the same hospital, and 44.7%in the non-PCT group in other hospitals. Patients in the PCT group had lower odds of receiving antibiotics in the first 7days of admission (OR, 0.33; 95%CI, 0.16-0.66 compared with the same hospital; OR, 0.42; 95%CI, 0.28-0.62 compared with the other hospitals). The proportion of patients receiving antibiotic prescription during the total admission was 35.2%, 43.9%, and 54.5%, respectively. The PCT group had lower odds of receiving antibiotics during the total admission only when compared with the other hospitals (OR, 0.23; 95%CI, 0.08-0.63). There were no significant differences in other secondary end points, except for readmission in the PCT group vsthe other hospitals group. PCT-guided antibiotic prescription reduces antibiotic prescription rates in hospitalized patients with COVID-19, without major safety concerns.

Isotope effect on hydrogen storage properties of Ti and Nb co-substituted ZrCo alloy

In our previous study, we showed that the anti-disproportionation properties of Zr0.8Ti0.2-xNbxCo alloys were remarkably improved by the co-substitution of Zr with Ti and Nb. However, the practical application of these alloys in handling of hydrogen isotopes necessitates the first hand knowledge of hydrogen isotope effect. Herein, we discuss the hydrogen isotope effect on storage properties of Zr0.8Ti0.2-xNbxCo alloys. According to PCT measurements on desorption of deuterium from the Zr0.8Ti0.2-xNbxCo deuterides and comparison with corresponding hydrides, the deuterides require relatively lower temperature to achieve the desired equilibrium pressure. DSC measurements reveal a significant decrease in the activation energy for hydrogen/deuterium desorption reactions when Zr is substituted with Ti and Nb. Furthermore, it is observed that the activation energy of deuterium desorption is lower than the desorption of hydrogen from analogous hydride. Isotope effect on isothermal disproportion studies on Zr0.8Ti0.2-xNbxCo-deuterides divulge that Zr0.8Ti0.2-xNbxCo-deuterides have superior anti-disproportionation properties over corresponding hydrides, and further improvement is anticipated for the Zr0.8Ti0.2-xNbxCo-tritides. This study revealed the significant impact of Ti and Nb co-substitution on hydrogen isotope storage properties of Zr0.8Ti0.2-xNbxCo alloys, making them potential candidates for handling hydrogen isotopes.

274. Epidemiology and Antimicrobial Treatment Impact of Procalcitonin in Patients with COVID-19

Abstract Background Procalcitonin (PCT) is often measured in patients with signs of bacterial infection. PCT is often elevated in bacterial pneumonia and septic shock and usually low in viral infections. Recent studies have found a correlation between PCT and disease severity in COVID-19, and most patients receive antibiotics despite bacterial co-infection being rare. We sought to characterize PCT trends in COVID-19, assess its relation to bacterial pneumonia, and assess its relation to clinical decision making around antimicrobial use. Methods We included patients ≥18 hospitalized at Michigan Medicine (3/1/20–10/31/21), positive for COVID-19, with ≥ 1 PCT measurement. Structured query was used to retrospectively extract data. Patients started on an antibiotic underwent retrospective chart review by 2 reviewers for presence of bacterial pneumonia (bPNA), and were classified as having proven, probable, possible, or no bPNA (Figure 1). Multivariable models controlling for time from start of the pandemic, demographics, and comorbidities were used to determine associations of PCT and bPNA with antimicrobial use. Figure 1:Flow diagram of patients included in analyses Results 793 patients met inclusion criteria, with 224 (28.2%) initiated on antibiotics. Of these 224, 33 (14.7%) had proven/probable bPNA, 125 (55.8%) had possible bPNA, and 66 (29.5%) had no bPNA. On average, patients had 2.6 ±3.7 (mean ±SD) PCT measurements, with 4.1 ±5.2 if on antibiotics vs. 2.0 ±2.6 if not. Initial PCT was higher in those on antibiotics and highest in those with proven/probable bPNA (Table 1). After adjustment for confounders, initial PCT was associated with antibiotic initiation (OR 1.68, 95% CI 1.47-1.91, p &amp;lt; 0.0001) (Table 2). Initial PCT (RR 1.11, 95% CI 1.03-1.20, p=0.008), change in PCT over time (RR 1.03, 95% CI 1.01-1.05, p=0.007), and bPNA category (RR 1.51, 95% CI 1.23-1.84, p &amp;lt; 0.0001) were associated with antibiotic duration (Table 3). Table 1:Number of PCT measures by antibiotic and bPNA statusTable 2:Multivariable logistic regression model results for covariate associations with antibiotic initiation (n=793)Table 3:Multivariable negative binomial model results for covariate associations with antibiotic duration (n=224) Conclusion PCT was elevated in patients with COVID-19, but more pronounced with bPNA. Antibiotics were started in &amp;gt; 25% of patients, regardless of bPNA. PCT trends associate with the decision to initiate antibiotics and treatment duration, independent of bPNA and comorbidities. Future prospective studies should determine if PCT can be used to safely make decisions around antibiotic treatment for bacterial infection during COVID-19. Disclosures Krishna Rao, MD, MS, Merck &amp; Co., Inc.: Grant/Research Support|Seres Therapeutics: Advisor/Consultant|Summit Therapeutics: Advisor/Consultant.

Role of immature platelet fraction (IPF) in sepsis patients: A systematic review.

Sepsis is extremely common amongst critically ill patients and requires early diagnosis. Hence, identifying a biomarker that could acknowledge sepsis at its prior stage is of vital significance. Immature platelets are a percentage of circulating platelets that contain RNA and is a newer parameter that is measured using automated hematology analyzers in diagnosing sepsis. This review article discusses 10 articles that reveal the role of immature platelet fraction in predicting the onset of sepsis and its relationship with mortality in sepsis. Literature search was done using PubMed, Scopus and Google Scholar and words like platelet indices and immature platelet fraction were typed in the search bar. The aim of this review article is to present a precise form of data that talk about immature platelet fraction (IPF) and its association with the severity and mortality of sepsis. Five out of 10 articles suggest that immature platelet fraction can predict the onset of sepsis and eight out of 10 articles suggest that increased IPF values are associated with high mortality.

Analytical evaluation of the novel VITROS BRAHMS procalcitonin immunoassay

To determine the analytical performance of Novel VITROS BRAHMS Procalcitonin Immunoassay on VITROS 3600 and correlation with BRAHMS PCT sensitive KRYPTOR reference method. Analytical performances including imprecision studies, linearity, limit of detection (LoD) and determination of hemolysis index were performed for VITROS BRAHMS PCT assay. Imprecision was assessed on plasma pool and internal control with 2 levels. The method comparison was performed using 162 plasma obtained from clinical departments. The total imprecision was acceptable and all CV were <5%. The LoD was in accordance with manufacturer’s claims. The equation of linearity in the lower range was found to be y = 1.0014x – 0.0091, with r2 = 1. No interference to hemoglobin up to 11 g/L was observed. Correlation studies showed a good correlation between PCT measurements using VITROS BRAHMS PCT assay against KRYPTOR system including for values lower than 2 µg/L. The novel VITROS BRAHMS PCT assay from OrthoClinical Diagnostics shows analytical performances acceptable for clinical use. In addition, the concordance with KRYPTOR method was fine at all clinical cut-offs.

Experimental investigations of AB5-type alloys for hydrogen separation from biological gas streams

AB5-type intermetallic compounds are suitable materials for hydrogen separation due to their ability selectively absorb hydrogen from different gas streams, including biologically produced ones. Recent studies show that metal hydride-based purification systems can effectively extract hydrogen from biogas with high CO2 concentration. Alloys LaNi5-xMx (M = Fe, Al, Mn, Sn) are prepared and activated during several cycles of H2 sorption/desorption and their PCT properties are measured in Sievert's type apparatus. Two compositions LaNi4.4Fe0.3Al0.3 and LaNi4.6Mn0.2Al0.2 are chosen for further investigations because they meet the requirements for biohydrogen separation system. After PCT measurements of 50-g samples, metal hydride powders are investigated by means of Quantochrome Nova 1200 and scanning electron microscopy to determine porosity, average particle size, specific surface area and permeability of metal hydride bed. Powder bed permeabilities are defined as 9.08 × 10−13 m2 for LaNi4.4Fe0.3Al0.3 and 6.86 × 10−13 m2 for LaNi4.6Mn0.2Al0.2 by Kozeny-Carman equation. AB5 type LaNi4.4Fe0.3Al0.3 and LaNi4.6Mn0.2Al0.2 alloys show good characteristics: low equilibrium pressures 0.025–0.03 MPa and acceptable reversible hydrogen capacity 1.1 %wt. for stationary hydrogen separation system.

Correlation and Assessment of Cost-Effectivity of Simultaneous PCT and CRP Measurements for Patients with Community-Acquired Pneumonia and COPD Inflamation

Amaç: Bakteriyel enfeksiyonlar önemli morbidite ve mortalite nedenidir. Serum prokalsitonin ve C-reaktif protein sistemik inflamasyon ve bakteriyel enfeksiyonların tanı, tedavi ve takibinde önemli belirteçlerdir. Bu çalışmada nihai tanıları pnömoni ve/veya KOAH alevlenmesi olan hastalarda son zamanlarda enfeksiyon takibinde sıklıkla kullanılmaya başlanan prokalsitonin ile klasik belirteç olarak kullanılan C-reaktif protein düzeyleri arasındaki korelasyon araştırıldı. Ayrıca alt solunum yolu enfeksiyonu tanısı ya da yönetimi için C-reaktif proteinin mi, prokalsitoninin mi maliyet etkililik açısından yararlı olduğunu saptamayı amaçladık.Gereç ve Yöntemler: Toplam 1948 hastadan elde edilmiş 4712 örnekten eş zamanlı çalışılan prokalsitonin ve C-reaktif protein sonuçları değerlendirildi. Örneklerden 499’u (%10.6) KOAH alevlenmesi (Grup I), 1480’i (%31.4) pnömoni (Grup II) ve 2733 (%58)’i KOAH alevlenmesi ve pnömoni (Grup III) tanısı almış hastaların örneklerinden oluşuyordu.Bulgular: C-reaktif protein ve prokalsitonin düzeyleri arasında pozitif güçlü korelasyon saptandı (rho=0.512, p&amp;lt;0.001). Yine prokalsitonin ve C-reaktif protein arasındaki grup içi değerlendirmede Grup I, Grup II ve Grup III’de pozitif güçlü korelasyon tespit edildi (sırasıyla rho=0.539, p&amp;lt;0.001; rho=0.509, p&amp;lt;0.001; rho=0.511, p&amp;lt;0.001).Sonuç: Prokalsitoninin C-reaktif protein ile korelasyon gösterdiği, enfeksiyonun ileri dönem takibinde yüksek maliyetli prokalsitonin yerine C-reaktif protein ölçümünün kullanılmasının uygun olacağı kanaatine varılmıştır.

Experimental comparison of proton CT and dual energy x-ray CT for relative stopping power estimation in proton therapy

Proton computed tomography (pCT) has been proposed as an alternative to x-ray computed tomography (CT) for acquiring relative to water stopping power (RSP) maps used for proton treatment planning dose calculations. In parallel, it has been shown that dual energy x-ray CT (DECT) improves RSP accuracy when compared to conventional single energy x-ray CT. This study aimed at directly comparing the RSP accuracy of both modalities using phantoms scanned at an advanced prototype pCT scanner and a state-of-the-art DECT scanner.Two phantoms containing 13 tissue-mimicking inserts of known RSP were scanned at the pCT phase II prototype and a latest generation dual-source DECT scanner (Siemens SOMATOM Definition FORCE). RSP accuracy was compared by mean absolute percent error (MAPE) over all inserts. A highly realistic Monte Carlo (MC) simulation was used to gain insight on pCT image artifacts which degraded MAPE.MAPE was 0.55% for pCT and 0.67% for DECT. The realistic MC simulation agreed well with pCT measurements (). Both simulation and experimental results showed ring artifacts in pCT images which degraded the MAPE compared to an ideal pCT simulation (). Using the realistic simulation, we could identify sources of artifacts, which are attributed to the interfaces in the five-stage plastic scintillator energy detector and calibration curve interpolation regions. Secondary artifacts stemming from the proton tracker geometry were also identified.The pCT prototype scanner outperformed a state-of-the-art DECT scanner in terms of RSP accuracy (MAPE) for plastic tissue mimicking inserts. Since artifacts tended to concentrate in the inserts, their mitigation may lead to further improvements in the reported pCT accuracy.

Validation of the Procalcitonin Assay on the Abbott Architect i1000.

Procalcitonin (PCT) is an emerging biomarker for detecting sepsis. Recently, the US Food and Drug Administration cleared the expanded use of this biomarker for guiding clinicians regarding antibiotic treatment. To our knowledge, there are no published method validations for the Abbott Architect PCT assay. This article will discuss the process of method validation of the B·R·A·H·M·S PCT assay on the Abbott Architect platform. We studied the precision, accuracy, and linearity of the Architect method following the guidance of the Clinical and Laboratory Standards Institute EP5-A2 document. Furthermore, we also tested the impact of major sources of interference from hemolysate, lipoproteins, and bilirubin. To validate the Architect method, we compared patients' serum PCT measurements with our previously established Mini VIDAS (bioMerieux) PCT assay. Statistical analysis showed that the 2 assays have good correlation (r > 0.99), slope of 1.023, and intercept of -0.760. The calculated bias is -7.435%. The Architect method showed good precision with %CV < 3.5% for both interassay and intraassay compared with %CV < 6.5% for Mini VIDAS, which was previously determined at our institution. No bias >10% was observed with the Architect method when pooled serum samples were spiked with interferants. The turnaround time for both platforms was the same (20 min); however, in contrast with Mini VIDAS, the Architect system has automated pipetting of samples and can perform multiple assays simultaneously. These results showed that the Architect B·R·A·H·M·S PCT assay has analytical characteristics conducive for diagnostic use in clinical laboratories. Our method validation report will be beneficial for other institutions to adapt this assay on existing Abbott Architect i1000 immunoassay analyzers.

Interleukin-18 serum levels in sepsis: Correlation with disease severity and inflammatory markers

PurposeSepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection and a syndrome shaped by pathogen and host factors with characteristic that evolve over time. The study was conducted to evaluate the prognostic and discriminative value of IL-18 assessment in comparison to PCT, CRP, WBC in early stage of sepsis and septic shock. MethodsAn observational and prospective study was conducted in the group of 40 ICU patients with diagnosis of sepsis or septic shock, serum PCT, IL-18, CRP and WBC measurements were performed on admission, and on the 2nd, 3rd and 5th therapy day. The level of IL-18 was determined with commercially available test according to manufacturer’s protocol. ResultsThere were no statistically significant differences in IL-18 levels in survivors vs non-survivors and in sepsis vs septic shock subgroups the IL-18 levels were statistically significant in the course of the study except for the 5th day. ConclusionThe PCT, CRP and WBC levels revealed no significant differences between any analyzed subgroups in all time points during study. According to our results the IL-18 is a biomarker better differentiating sepsis and septic shock status than PCT, CRP and WBC but with no prognostic impact.

Plasma procalcitonin concentrations predict organ dysfunction and outcome in dogs with sepsis

BackgroundProcalcitonin (PCT) is a valuable prognostic biomarker in human sepsis that is predictive of organ dysfunction, septic shock and mortality. Data on PCT in dogs is limited. This study aimed to investigate the prognostic value of baseline and serial PCT measurements in dogs with sepsis and to determine the association between PCT and sepsis severity and the presence of organ dysfunction. PCT concentrations were measured in citrated plasma samples collected from 53 dogs with sepsis at the time of admission (T0, n = 53) and at 24 h (T1, n = 35) and 48 h (T2, n = 30) post-admission using a commercial ELISA. Dogs were classified by sepsis severity (sepsis without organ dysfunction; severe sepsis; septic shock) and outcome (survivors; non-survivors). Organ dysfunctions were recorded at T0 and during hospitalization, and the APPLEfast score calculated at T0. Healthy dogs (n = 12) were used as controls.ResultsThere were 18 septic dogs without organ dysfunction, 24 dogs with severe sepsis and 11 with septic shock. Baseline PCT concentrations were significantly greater in dogs with sepsis compared to healthy controls (P < 0.0001), and in dogs with septic shock compared to dogs without cardiovascular compromise (P = 0.01). Baseline PCT was significantly correlated with organ dysfunction (P = 0.003). Declining PCT concentrations were documented in survivors at T1 and T2 compared to PCT at T0 (P = 0.0006), and PCT clearance at 24 h was significantly higher in survivors (n = 38) compared to non-survivors (n = 15) (P = 0.037). Canine APPLEfast score was not predictive of sepsis severity, the development of MODS or outcome.ConclusionIn dogs with sepsis, PCT concentrations at hospital admissions are predictive of organ dysfunction and septic shock. Serial procalcitonin monitoring may offer valuable prognostic information in canine sepsis, wherein early decreases in PCT concentrations are associated with survival.

Dual-tuning the thermodynamics and kinetics: Magnesium-naphthalocyanine nanocomposite for low temperature hydrogen cycling

2,11,20,29-Tetra-tert-butyl-2,3-naphthalocyanine (TTBNc) was used as an alternative host to support magnesium (Mg) nanoparticles. After deposition and decomposition of dibutylmagnesium on TTBNc, Mg nanoparticles of around 4 nm supported on TTBNc were observed by TEM. These TTBNc stabilized Mg nanoparticles were found to absorb hydrogen at 100 °C and release hydrogen from 75 °C. The Mg-TTBNc material showed good hydrogen cycling properties and structural stability. Kinetic measurements showed fast hydrogen absorption within 2 min at 150 °C. The hydrogen desorption kinetics were slower at the same temperature but faster at 250 °C with 80% of the hydrogen desorbed within 1 h. Enthalpy and entropy for hydrogen uptake and release in Mg-TTBNc determined from PCT measurements were found to be of 52.7 ± 4.9 kJ mol−1 H2 and 107.8 ± 9.4 J K−1 mol−1 H2, respectively. These values are much lower than those of bulk Mg.

Effects of Mo alloying on the structure and hydrogen-permeation properties of Nb metal

Effects of alloying Nb with Mo on the structure and hydrogen permeation properties of Nb metal have been investigated by XRD analysis, PCT measurements, and three-point bending tests. The results indicate that all the as-prepared Nb100-xMox (x = 2, 7, 14) alloy samples are Nb-based solid solutions with a BCC structure, which are hydrogenated into their corresponding hydrides with the NbH0.95 phase after interaction with hydrogen. The lattice deformations of the BCC structure and NbH0.95 phase are due to the difference in size between Nb and Mo atoms. The Nb86Mo14 sample has a higher hydrogen-diffusion coefficient value (1.84 × 10−9 cm/s), higher hydride-formation enthalpies (- 35.8 kJ/(mol·H2)) with the maximum force and displacement before/after the hydrotreatment, indicating that alloying with Mo can greatly improve the hydrogen-diffusion behavior and anti-bending properties of Nb metal.

Hydrogen Sorption Characteristics of ZrCrAl Ternary Alloy as a Function of Milling Time

Intermetallic compounds which absorb large quantities of hydrogen have received considerable attention recently. The AB2 laves phase intermetallic compound is known to be a potential material for hydrogen storage, owing to its large storage capacity, ease of activation and rapid reaction rate with hydrogen. In this work Al has been chosen as a substitute material for Cr and ZrCrAl ternary alloy is prepared using arc furnace. The mechanical alloying process has been introduced to produce nanocrystalline material. This paper presents comprehensive study on structural aspects of ball milled ZrCrAl alloy. On comparison of the XRD data, the broadening was found in the peak width with the increase of milling time which is clear indication of refinement of crystallite size. This refinement could also be confirmed from the SEM analysis also. PCT measurements were performed for a temperature range 303 K–373 K.

Serial Procalcitonin Levels Correlate with Microbial Etiology in Hospitalized Patients with Pneumonia

BackgroundProcalcitonin (PCT) is a biomarker that is finding increasing diagnostic and prognostic utility in lower respiratory infections. It remains unclear, however, whether it can be helpful in predicting the bacterial etiology of pneumonia, with a view to informing antibiotic choice and duration. This study examines the relationship between serial PCT measurements and microbial etiology in patients hospitalized for pneumonia to determine whether changes in PCT levels provide discriminatory information on microbial etiology.MethodsWe performed a subgroup analysis of data from a prospective cohort study of 505 patients admitted to a tertiary care center with findings concerning for pneumonia. Microbial etiology of pneumonia was determined from high quality respiratory samples, blood cultures or other relevant diagnostic tests according to standard protocols. Procalcitonin levels were measured serially during the first four days of hospitalization. We compared procalcitonin levels between different bacterial etiologies over the first four days of admission, using the Mann–Whitney-U test to assess for statistical significance.ResultsOut of 505 patients, the diagnosis of pneumonia was adjudicated in 317, and bacterial etiology determined in 62 cases. The predominant pathogens were Staphylococcus aureus (N = 18), Streptococcus pneumoniae (N = 6), Pseudomonas aeruginosa (N = 11) and Haemophilus influenza (N = 5). Admission levels of PCT were lowest in Pseudomonas infections and highest in pneumococcal infections, though not reaching statistical significance. On hospital days two and three, pneumococcal procalcitonin levels were significantly higher than all other etiologies, but on day four, there was no statistically significant difference in PCT values for different microbial etiologies.ConclusionSerial procalcitonin levels during the early course of bacterial pneumonia reveal a difference between pneumococcal and other bacterial etiologies, and may have an adjunct role in guiding antibiotic choice and duration.Disclosures All authors: No reported disclosures.