Topology Optimization Enables High-Q Metasurface for Color Selectivity.

Nonlocal metasurfaces, exemplified by resonant waveguide gratings (RWGs), spatially and angularly configure optical wavefronts through narrow-band resonant modes, unlike the broad-band and broad-angle responses of local metasurfaces. However, forward design techniques for RWGs remain constrained at lower efficiency. Here, we present a topology-optimized metasurface resonant waveguide grating (MRWG) composed of titanium dioxide on a glass substrate capable of operating simultaneously at red, yellow, green, and blue wavelengths. Through adjoint-based topology optimization, while considering nonlocal effects, we significantly enhance its diffraction efficiency, achieving numerical efficiencies up to 78% and Q-factors as high as 1362. Experimentally, we demonstrated efficiencies of up to 59% with a Q-factor of 93. Additionally, we applied our topology-optimized metasurface to color selectivity, producing vivid colors at 4 narrow-band wavelengths. Our investigation represents a significant advancement in metasurface technology, with potential applications in see-through optical combiners and augmented reality platforms.

Patient Preference for Catheter-Based Hypertension Therapy and Subgroup Analysis: A Pilot Study Based on Taiwan Consensus on Renal Denervation.

Ojective: To understand hypertensive patients' preference for catheter-based therapy to manage hypertension. Methods: Survey data regarding catheter-based therapies performed at MacKay Memorial Hospital in Taipei, Taiwan, between 2019-2020 were analyzed. The questionnaire was circulated either in the clinics or during admission. A total of 46 patients completed the questionnaire. Results: A total of 46 patients (mean age 53.4 ± 13.5 years, 78.3% male) completed the questionnaire. In subgroup analysis according to Taiwan renal denervation (RDN) consensus, patients with drug intolerance (61.8% vs. 31.3%, p = 0.02) were more likely to choose RDN. Moreover, although lacking statistical significance, it is noteworthy that numerically more of the resistant hypertension group (55.6% vs. 28.0%, p = 0.09) and non-adherence group (38.5% vs. 30.0%, p = 0.20) were willing to undergo RDN. Conversely, numerically fewer patients with hypertension-mediated organ damage accepted RDN compared to those who did not have hypertension-mediated organ damage (26.1% vs. 43.5%, p = 0.21), although this disparity did not reach statistical significance. Conclusions: Approximately one-third of the patients expressed interest in considering RDN in this study. The most influential factor in patients' preference for RDN was drug intolerance due to medication-related side effects.

Comprehensive N- and O-Glycoproteomic Analysis of Multiple Chinese Hamster Ovary Host Cell Lines.

Glycoproteomic analysis of three Chinese hamster ovary (CHO) suspension host cell lines (CHO-K1, CHO-S, and CHO-Pro5) commonly utilized in biopharmaceutical settings for recombinant protein production is reported. Intracellular and secreted glycoproteins were examined. We utilized an immobilization and chemoenzymatic strategy in our analysis. Glycoproteins or glycopeptides were first immobilized through reductive amination, and the sialyl moieties were amidated for protection. The desired N- or O-glycans and glycopeptides were released from the immobilization resin by enzymatic or chemical digestion. Glycopeptides were studied by Orbitrap Liquid chromatography-mass spectrometry (LC/MS), and the released glycans were analyzed by Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF). Differences were detected in the relative abundances of N- and O-glycopeptide types, their resident and released glycans, and their glycoprotein complexity. Ontogeny analysis revealed key differences in features, such as general metabolic and biosynthetic pathways, including glycosylation systems, as well as distributions in cellular compartments. Host cell lines and subfraction differences were observed in both N- and O-glycan and glycoprotein pools. Differences were observed in sialyl and fucosyl glycan distributions. Key differences were also observed among glycoproteins that are problematic contaminants in recombinant antibody production. The differences revealed in this study should inform the choice of cell lines best suited for a particular bioproduction application.

Clinical benefits of inhaled ciclesonide for hospitalized patients with COVID-19 infection: a retrospective study.

BACKGROUND: The successful management of patients infected with coronavirus disease 2019 (COVID-19) with inhaled ciclesonide has been reported, however few studies have investigated its application among hospitalized patients. METHODS: This retrospective cohort study enrolled all adult patients admitted to our hospital with confirmed COVID-19 infection from May to June 2021. Critical patients who received mechanical ventilation within 24 h after admission and those who started ciclesonide more than 14 days after symptom onset were excluded. The in-hospital mortality rate was compared between those who did and did not receive inhaled ciclesonide. RESULTS: A total of 269 patients were enrolled, of whom 184 received inhaled ciclesonide and 85 did not. The use of ciclesonide was associated with lower in-hospital mortality (7.6% vs. 23.5%, p = 0.0003) and a trend of shorter hospital stay (12.0 (10.0-18.0) days vs. 13.0 (10.0-25.3) days, p = 0.0577). In subgroup analysis, the use of inhaled ciclesonide significantly reduced mortality in the patients with severe COVID-19 infection (6.8% vs. 50.0%, p < 0.0001) and in those with a high risk of mortality (16.4% vs. 43.2%, p = 0.0037). The use of inhaled ciclesonide also reduced the likelihood of receiving mechanical ventilation in the patients with severe COVID-19 infection. After multivariate analysis, inhaled ciclesonide remained positively correlated with a lower risk of in-hospital mortality (odds ratio: 0.2724, 95% confidence interval: 0.087-0.8763, p = 0.0291). CONCLUSIONS: The use of inhaled ciclesonide in hospitalized patients with COVID-19 infection can reduce in-hospital mortality. Further randomized studies in patients with moderate to severe COVID-19 infection are urgently needed.

Function of an anti-lipopolysaccharide factor (ALF) isoform isolated from the hemocytes of the giant freshwater prawn Macrobrachium rosenbergii in protecting against bacterial infection.

In this study, a 780-bp full-length cDNA encoding Macrobrachium rosenbergii anti-lipopolysaccharide factor (MrALF) from hemocytes was cloned and identified. The ALF isoform exhibited immune activities, and its concentration in hemolymph was determined. An in vivo expression study showed that the ALF mRNA level of hemocytes could be induced by lipopolysaccharides (LPSs) in an exposure time-dependent manner. Purified recombinant MrALF (rMrALF) expressed in the yeast Pichia pastoris SMD1168 eukaryotic protein expression system demonstrated antibacterial activity against the Gram-negative prawn pathogen Aeromonas hydrophila (minimum inhibitory concentration (MIC)=0.806µM, minimum bactericidal concentration (MBC)=1.606µM) but not the Gram-positive pathogen Lactococcus garvieae exposed to 25.696µM of rALF. However, rMrALF can bind to Gram-negative and -positive bacteria. An in vivo expression study demonstrated that the ALF concentrations in prawn hemocytes and plasma were 0.176µM and 0.168µM, respectively; following LPS treatment for 6h, the corresponding concentrations were 0.133µM in hemocytes and 0.272µM in plasma. Furthermore, the percentage of hemocytes phagocytosing bacteria cells was higher in hemoyctes previously treated with MrALF than those treated with sterile medium. These results suggest that in the innate immune response of M. rosenbergii, the MrALF from hemocytes may play an opsonin during a bacterial invasion.

Pulmonary embolism in chronic obstructive pulmonary disease: a population-based cohort study.

BACKGROUND: To evaluate the incidence of pulmonary embolism (PE) in patients with chronic obstructive pulmonary disease (COPD) in Taiwan. METHODS: This was a retrospective population-based cohort study using data retrieved from Taiwan's National Health Insurance Research Database (2000 to 2008), which contains 99% of Taiwanese healthcare data. The evaluations included 355,878 COPD patients and 355,878 non-COPD patients for comparison. RESULTS: The incidence of PE in the COPD cohort was 12.31 per 10,000 person-years (1.37/10,000 persons/y), which was approximately 4-times higher than in the comparison cohort (0.35/10,000 persons/y). In the COPD cohort, risk of PE was higher in the young age group (20-59 y, HR 4.64, 95% CI 3.06-7.03) than in other age groups. Risk of PE was higher in patients with COPD combined with hypertension, coronary artery disease, and cancer, or those with previous operation (HR 4.16, 4.75, 4.56, and 4.50 respectively) than in those with COPD and no comorbidity. CONCLUSIONS: The overall incidence of PE is lower in Taiwan than in western countries. However, the prevalence of PE in COPD patients is higher than in non-COPD patients and increases with age. It is crucial to incorporate PE into the differential diagnosis of COPD exacerbation for clinical physicians.

Left Atrial Hemodynamics and Clinical Utility in Heart Failure.

Comprehensive knowledge of the left atrium (LA) and its pathophysiology has emerged as an important clinical and research focus in the heart failure (HF) arena. Although studies on HF focusing on investigating left ventricular remodeling are numerous, those on atrial structural and functional changes have received comparatively less attention. Studies on LA remodeling have recently received increasing attention, and LA pressure (LAP) has become a novel target for advanced monitoring and is a potential therapeutic approach for treating HF. Various devices specifically designed for the direct measurement of LAP have been developed to optimize HF treatment by reducing LAP. This review focuses on LA hemodynamic monitoring and effective LAP decompression.

Recruitment-Potential-Oriented Mechanical Ventilation Protocol and Narrative Review for Patients with Acute Respiratory Distress Syndrome.

Even though much progress has been made to improve clinical outcomes, acute respiratory distress syndrome (ARDS) remains a significant cause of acute respiratory failure. Protective mechanical ventilation is the backbone of supportive care for these patients; however, there are still many unresolved issues in its setting. The primary goal of mechanical ventilation is to improve oxygenation and ventilation. The use of positive pressure, especially positive end-expiratory pressure (PEEP), is mandatory in this approach. However, PEEP is a double-edged sword. How to safely set positive end-inspiratory pressure has long been elusive to clinicians. We hereby propose a pressure-volume curve measurement-based method to assess whether injured lungs are recruitable in order to set an appropriate PEEP. For the most severe form of ARDS, extracorporeal membrane oxygenation (ECMO) is considered as the salvage therapy. However, the high level of medical resources required and associated complications make its use in patients with severe ARDS controversial. Our proposed protocol also attempts to propose how to improve patient outcomes by balancing the possible overuse of resources with minimizing patient harm due to dangerous ventilator settings. A recruitment-potential-oriented evaluation-based protocol can effectively stabilize hypoxemic conditions quickly and screen out truly serious patients.

The clinical application of traditional Chinese medicine NRICM101 in hospitalized patients with COVID-19.

BACKGROUND: The aim of this study was to assess the efficacy and safety of NRICM101 in hospitalized patients with COVID-19. RESEARCH DESIGN AND METHODS: We conducted a retrospective study from 20 April 2021 to 8 July 2021, and evaluated the safety and outcomes (mortality, hospital stay, mechanical ventilation, oxygen support, diarrhea, serum potassium) in COVID-19 patients. Propensity score matching at a 1:2 ratio was performed to reduce confounding factors. RESULTS: A total of 201 patients were analyzed. The experimental group (n = 67) received NRICM101 and standard care, while the control group (n = 134) received standard care alone. No significant differences were observed in mortality (10.4% vs. 14.2%), intubation (13.8% vs. 11%), time to intubation (10 vs. 11 days), mechanical ventilation days (0 vs. 9 days), or oxygen support duration (6 vs. 5 days). However, the experimental group had a shorter length of hospitalization (odds ratio = 0.12, p = 0.043) and fewer mechanical ventilation days (odds ratio = 0.068, p = 0.008) in initially severe cases, along with an increased diarrhea risk (p = 0.035). CONCLUSION: NRICM101 did not reduce in-hospital mortality. However, it shortened the length of hospitalization and reduced mechanical ventilation days in initially severe cases. Further investigation is needed.

Personalized Management for Heart Failure with Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous clinical syndrome with multiple underlying mechanisms and comorbidities that leads to a variety of clinical phenotypes. The identification and characterization of these phenotypes are essential for better understanding the precise pathophysiology of HFpEF, identifying appropriate treatment strategies, and improving patient outcomes. Despite accumulating data showing the potentiality of artificial intelligence (AI)-based phenotyping using clinical, biomarker, and imaging information from multiple dimensions in HFpEF management, contemporary guidelines and consensus do not incorporate these in daily practice. In the future, further studies are required to authenticate and substantiate these findings in order to establish a more standardized approach for clinical implementation.

Optimal Timing of Targeted Temperature Management for Post-Cardiac Arrest Syndrome: Is Sooner Better?

Targeted temperature management (TTM) is often considered to improve post-cardiac arrest patients' outcomes. However, the optimal timing to initiate cooling remained uncertain. This retrospective analysis enrolled all non-traumatic post-cardiac arrest adult patients with either out-of-hospital cardiac arrest (OHCA) or in-hospital cardiac arrest (IHCA) who received TTM from July 2015 to July 2021 at our hospital. The values of time delay before TTM and time to target temperature were divided into three periods according to optimal cut-off values identified using receiver operating characteristic curve analysis. A total of 177 patients were enrolled. A shorter time delay before TTM (pre-induction time) was associated with a lower survival chance at 28 days (32.00% vs. 54.00%, p = 0.0279). Patients with a longer cooling induction time (>440 minis) had better neurological outcomes (1.58% vs. 1.05%; p = 0.001) and survival at 28 days (58.06% vs. 29.25%; p = 0.006). After COX regression analysis, the influence of pre-induction time on survival became insignificant, but patients who cooled slowest still had a better chance of survival at 28 days. In conclusion, a shorter delay before TTM was not associated with better clinical outcomes. However, patients who took longer to reach the target temperature had better hospital survival and neurological outcomes than those who were cooled more rapidly. A further prospective study was warranted to evaluate the appropriate time window of TTM.

Outcome prediction in hospitalized COVID-19 patients: Comparison of the performance of five severity scores.

Background: The aim of our study was to externally validate the predictive capability of five developed coronavirus disease 2019 (COVID-19)-specific prognostic tools, including the COVID-19 Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Shang COVID severity score, COVID-intubation risk score-neutrophil/lymphocyte ratio (IRS-NLR), inflammation-based score, and ventilation in COVID estimator (VICE) score. Methods: The medical records of all patients hospitalized for a laboratory-confirmed COVID-19 diagnosis between May 2021 and June 2021 were retrospectively analyzed. Data were extracted within the first 24 h of admission, and five different scores were calculated. The primary and secondary outcomes were 30-day mortality and mechanical ventilation, respectively. Results: A total of 285 patients were enrolled in our cohort. Sixty-five patients (22.8%) were intubated with ventilator support, and the 30-day mortality rate was 8.8%. The Shang COVID severity score had the highest numerical area under the receiver operator characteristic (AUC-ROC) (AUC 0.836) curve to predict 30-day mortality, followed by the SEIMC score (AUC 0.807) and VICE score (AUC 0.804). For intubation, both the VICE and COVID-IRS-NLR scores had the highest AUC (AUC 0.82) compared to the inflammation-based score (AUC 0.69). The 30-day mortality increased steadily according to higher Shang COVID severity scores and SEIMC scores. The intubation rate exceeded 50% in the patients stratified by higher VICE scores and COVID-IRS-NLR score quintiles. Conclusion: The discriminative performances of the SEIMC score and Shang COVID severity score are good for predicting the 30-day mortality of hospitalized COVID-19 patients. The COVID-IRS-NLR and VICE showed good performance for predicting invasive mechanical ventilation (IMV).

Predicting the successful application of high-flow nasal oxygen cannula in patients with COVID-19 respiratory failure: a retrospective analysis.

BACKGROUND: The right time of high-flow nasal cannulas (HFNCs) application in COVID-19 patients with acute respiratory failure remains uncertain. RESEARCH DESIGN AND METHODS: In this retrospective study, COVID-19-infected adult patients with hypoxemic respiratory failure were enrolled. Their baseline epidemiological data and respiratory failure related parameters, including the Ventilation in COVID-19 Estimation (VICE), and the ratio of oxygen saturation (ROX index), were recorded. The primary outcome measured was the 28-day mortality. RESULTS: A total of 69 patients were enrolled. Fifty-four (78%) patients who intubated and received invasive mechanical ventilatory (MV) support on day 1 were enrolled in the MV group. The remaining fifteen (22%) patients received HFNC initially (HFNC group), in which, ten (66%) patients were not intubated during hospitalization were belong to HFNC-success group and five (33%) of these patients were intubated later due to disease progression were attributed to HFNC-failure group. Compared with those in the MV group, those in the HFNC group had a lower mortality rate (6.7% vs. 40.7%, p = 0.0138). There were no differences in baseline characteristics among the two groups; however, the HFNC group had a lower VICE score (0.105 [0.049-0.269] vs. 0.260 [0.126-0.693], p = 0.0092) and higher ROX index (5.3 [5.1-10.7] vs. 4.3 [3.9-4.9], p = 0.0007) than the MV group. The ROX index was higher in the HFNC success group immediately before (p = 0.0136) and up to 12 hours of HFNC therapy than in the HFNC failure group. CONCLUSIONS: Early intubation may be considered in patients with a higher VICE score or a lower ROX index. The ROX score during HFNCs use can provide an early warning sign of treatment failure. Further investigations are warranted to confirm these results.

High flow nasal cannulas (HFNCs) were widely used in patients with COVID-19 infection related hypoxemic respiratory failure. However, there were concerns about its failure and related delayed intubation may be associated with a higher mortality rate. This retrospective study revealed patients with higher baseline disease severity and higher VICE scores may be treated with primary invasive mechanical ventilation. On the contrary, if their baseline VICE score is low and ROX index is high, HFNCs treatment might be safely applied initially. The trends of serial ROX index values during HFNC use could be a reliable periscope to predict the HFNC therapy outcome, therefore avoided delayed intubation.

Metasurface-driven polarization-division multiplexing of PCSEL for optical communications.

Free-space optical communications hold promising advantages, including a large bandwidth, access to license-free spectrum, high data rates, quick and simple deployment, low power consumption, and relaxed quality requirements. Nevertheless, key technical challenges remain, such as a higher transmission efficiency, a lower transmission loss, and a smaller form factor of optical systems. Here, we demonstrate the viability of circular-polarization-multiplexed multi-channel optical communication using metasurfaces alongside a photonic-crystal surface-emitting laser (PCSEL) light source at wavelength of 940 nm. Through the light manipulation with metasurface, we split the linearly polarized incidence into left and right circular polarizations with desired diffraction angles. Such orthogonal polarization states provide a paradigm of polarization division multiplexing technique for light communication. The PCSEL light source maintains a low divergence angle of about 0.373 degrees after passing through an ultra-thin metasurface without further bulky collimator or light guide, making end-to-end (E2E) and device-to-device (D2D) communications available in a compact form. Both light source and modulated polarized light exhibit a - 3 dB bandwidth over 500 MHz, with successful 1 Gbit/s transmission demonstrated in eye diagrams. Our results affirm that metasurface effectively boosts transmission capacity without compromising the light source's inherent properties. Future metasurface designs could expand channel capacity, and its integration with PCSEL monolithically holds promise for reducing interface losses, thereby enhancing efficiency.

Does One Size Fit All? External Validation of the rCAST Score to Predict the Hospital Outcomes of Post-Cardiac Arrest Patients Receiving Targeted Temperature Management.

The revised post-Cardiac Arrest Syndrome for Therapeutic hypothermia (rCAST) score was proposed to predict neurologic outcomes and mortality among out-of-hospital cardiac arrest (OHCA) patients. However, it has rarely been validated outside Japan. Therefore, this study aimed to investigate this issue. All adult patients admitted to our medical intensive care unit for targeted temperature management (TTM) between July 2015 and July 2021 were enrolled. Their medical records were retrieved, and rCAST scores were calculated. A total of 108 post-cardiac arrest syndrome (PCAS) patients who received TTM were analyzed. According to the rCAST score, 49.1%, 50.0%, and 0.9% of the patients were classified as low, moderate, and high severity, respectively. The areas under the curves for the rCAST score were 0.806 (95% confidence interval [CI]: 0.719-0.876) and 0.794 (95% CI: 0.706-0.866) to predict poor neurologic outcomes and mortality at day 28, respectively. In contrast to the original report, only low-severity patients had favorable neurologic outcomes. The rCAST score showed moderate accuracy in our OHCA patients with PCAS who received TTM to predict poor neurologic outcomes and mortality at day 28.

Altered inflammatory responses in preterm children with cerebral palsy.

OBJECTIVE: Perinatal inflammatory responses contribute to periventricular leukomalacia (PVL) and cerebral palsy (CP) in preterm infants. Here, we examined whether preterm children with CP had altered inflammatory responses when school-aged. METHODS: Thirty-two preterm children with PVL-induced CP (mean [+/-standard deviation] age, 7.2 +/- 3.6 years) and 32 control preterm children with normal neurodevelopment (6.2 +/- 2.2 years) and matched for gestational age were recruited. We measured tumor necrosis factor (TNF)-alpha levels in the plasma and the supernatants of peripheral blood mononuclear cells (PBMCs) before and after lipopolysaccharide (LPS) stimulation, and proinflammatory gene expression in the PBMCs. RESULTS: TNF-alpha expression was significantly higher in the plasma (p < 0.001) and supernatants of LPS-stimulated PBMCs (p = 0.003) in the CP group than in the control group. After LPS stimulation, the intracellular TNF-alpha level in the PBMCs was significantly lower in the control group (p = 0.016) and significantly higher in the CP group (p = 0.01). The CP group also had, in their nonstimulated PBMCs, significantly higher mRNA levels of inflammatory molecules: toll-like receptor 4 (TLR-4) (p = 0.0023), TNF-alpha (p = 0.0016), transforming growth factor-beta-activated kinase 1 (p = 0.038), IkappaB kinase-gamma (p = 0.029), and c-Jun N-terminal kinase (p = 0.045). The TLR-4 mRNA levels in the PBMCs were highly correlated with TNF-alpha levels in LPS-stimulated PBMCs (Spearman rank correlation = 0.38, p = 0.03). INTERPRETATION: The finding that preterm children with PVL-induced CP have altered inflammatory responses indicates the possibility of programming effect of PVL or inflammation-related events during early life.

Characterization of timing jitter in a 5 GHz quantum dot passively mode-locked laser.

The timing jitter performance of a 5 GHz quantum dot passively mode-locked laser is investigated at different harmonics in the RF spectrum. The necessity of measuring the phase noise at relatively large harmonic numbers is motivated experimentally in the context of determining the corner frequency, its correlation to the RF linewidth, and the related white noise plateau level. The single-sideband phase noise with an integrated timing jitter of 211 fs (4-80 MHz) is reported. An all-microwave technique has been used to determine a pulse-to-pulse rms timing jitter of 96 fs/cycle. This low timing jitter value makes the chip-scale quantum dot mode-locked laser an attractive source for low noise applications such as optical clocking and sampling.

Harmonic mode-locking using the double interval technique in quantum dot lasers.

Passive harmonic mode-locking in a quantum dot laser is realized using the double interval technique, which uses two separate absorbers to stimulate a specific higher-order repetition rate compared to the fundamental. Operating alone these absorbers would otherwise reinforce lower harmonic frequencies, but by operating together they produce the harmonic corresponding to their least common multiple. Mode-locking at a nominal 60 GHz repetition rate, which is the 10(th) harmonic of the fundamental frequency of the device, is achieved unambiguously despite the constraint of a uniformly-segmented, multi-section device layout. The diversity of repetition rates available with this method is also discussed.

Low-dose lipopolysaccharide selectively sensitizes hypoxic ischemia-induced white matter injury in the immature brain.

Little is known about roles of inflammation and hypoxic ischemia (HI) in the generation of neuroinflammation and damage of blood-brain barrier (BBB) in the white matter (WM) that displays regional vulnerability in preterm infants. We investigated whether low-dose lipopolysaccharide (LPS) sensitizes HI-induced WM injury in postpartum (P) day 2 rat pups by selectively increasing neuroinflammation and BBB damage in the WM. Pups received LPS (0.05 mg/kg) (LPS + HI) or normal saline (NS + HI) followed by 90-min HI. LPS and NS group were the pups that had LPS or NS only. Myelin basic protein immunohistochemistry on P11 showed WM injury in LPS + HI group, but not in NS + HI, LPS, and NS groups. In contrast, no gray matter injury was found in the four groups. LPS + HI group also showed decreased number of oligodendrocytes in the WM 72-h postinsult. In the same brain region, increases of activated microglia, TNF-alpha expression, BBB leakage, and cleaved caspase-3 positive cells were much more prominent in LPS + HI group than in the other three groups 24-h postinsult. The oligodendrocytes were the major cells with cleaved caspase-3 expression. We concluded that low-dose LPS sensitized HI-induced WM injury in the immature brain by selectively up-regulating neuroinflammation and BBB damage in the WM.

Investigating antimicrobial activity in Rheinheimera sp. due to hydrogen peroxide generated by l-lysine oxidase activity.

A greenish yellow pigmented bacterial strain, designated GR5, was recently isolated from a freshwater culture pond for a soft-shell turtle. Phylogenetic analyses based on 16S rRNA gene sequences indicate that strain GR5 belongs to the genus Rheinheimera and its only closest neighbor is the type strain of Rheinheimera texasensis (98.2%). Based on the antibiogram assay, strain GR5 possesses a broad spectrum of antimicrobial activity including Gram-positive and Gram-negative bacteria, yeast, algae, and strain GR5 itself. Strain GR5 can synthesize a macromolecule with antimicrobial activity due to the generation of hydrogen peroxide and this antimicrobial effect can be inhibited by catalase. This antimicrobial activity is active only in complex culture media or chemically defined culture media containing l-lysine. This antimicrobial macromolecule in strain GR5 is shown to be a monomeric protein with a molecular mass of 71kDa and isoelectric point of approximately 3.68. Liquid chromatography-tandem mass spectrometry analyses reveal close similarity of a 19-amino acid fragment derived from this protein to the antibacterial protein, AlpP from the marine bacterium Pseudoalteromonas tunicata D2, and to the antibacterial protein, marinocine, from the marine bacterium Marinomonas mediterranea. This study explores the nature of antimicrobial macromolecule such as l-lysine oxidase. This is the first report on a freshwater bacterium producing antimicrobial activity by generating hydrogen peroxide through its enzymatic activity of l-lysine oxidase.