Variability in Blood Pressure Assessment in Patients Supported with the HeartMate 3TM

Targeted blood pressure (BP) control is a goal of left ventricular assist device medical management, but the interpretation of values obtained from noninvasive instruments is challenging. In the MOMENTUM 3 Continued Access Protocol, paired BP values in HeartMate 3 (HM3) patients were compared from arterial (A)-line and Doppler opening pressure (DOP) (319 readings in 261 patients) and A-line and automated cuff (281 readings in 247 patients). Pearson (R) correlations between A-line mean arterial (MAP) and systolic blood pressures (SBP) were compared with DOP and cuff measures according to the presence (\u3e1 pulse in 5 seconds) or absence of a palpable radial pulse. There were only moderate correlations between A-line and noninvasive measurements of SBP (DOP R = 0.58; cuff R = 0.47) and MAP (DOP R = 0.48; cuff R = 0.37). DOP accuracy for MAP estimation, defined as the % of readings within ± 10 mmHg of A-line MAP, decreased from 80% to 33% for DOP ≤ 90 vs. \u3e90 mmHg, and precision also diminished (mean absolute difference [MAD] increased from 6.3 ± 5.6 to 16.1 ± 11.4 mmHg). Across pulse pressures, cuff MAPs were within ±10 mmHg of A-line 62.9%-68.8% of measures and MADs were negligible. The presence of a palpable pulse reduced the accuracy and precision of the DOP-MAP estimation but did not impact cuff-MAP accuracy or precision. In summary, DOP may overestimate MAP in some patients on HM3 support. Simultaneous use of DOP and automated cuff and radial pulse may be needed to guide antihypertensive medication titration in outpatients on HM3 support

Switchable Gene Expression in Escherichia coli Using a Miniaturized Photobioreactor

We present a light-switchable gene expression system for both inducible and switchable control of gene expression at a single cell level in Escherichia coli using a previously constructed light-sensing system. The lambda cl repressor gene with an LVA degradation tag was expressed under the control of the ompC promoter on the chromosome. The green fluorescent protein (GFP) gene fused to a lambda repressor-repressible promoter was used as a reporter. This light-switchable system allows rapid and reversible induction or repression of expression of the target gene at any desired time. This system also ensures homogenous expression across the entire cell population. We also report the design of a miniaturized photobioreactor to be used in combination with the light-switchable gene expression system. The miniaturized photobioreactor helps to reduce unintended induction of the light receptor due to environmental disturbances and allows precise control over the duration of induction. This system would be a good tool for switchable, homogenous, strong, and highly regulatable expression of target genes over a wide range of induction times. Hence, it could be applied to study gene function, optimize metabolic pathways, and control biological systems both spatially and temporally.open0

Right ventricular dyssynchrony in patients with pulmonary hypertension is associated with disease severity and functional class

BACKGROUND: Abnormalities in right ventricular function are known to occur in patients with pulmonary arterial hypertension. OBJECTIVE: Test the hypothesis that chronic elevation in pulmonary artery systolic pressure delays mechanical activation of the right ventricle, termed dyssynchrony, and is associated with both symptoms and right ventricular dysfunction. METHODS: Fifty-two patients (mean age 46 ± 15 years, 24 patients with chronic pulmonary hypertension) were prospectively evaluated using several echocardiographic parameters to assess right ventricular size and function. In addition, tissue Doppler imaging was also obtained to assess longitudinal strain of the right ventricular wall, interventricular septum, and lateral wall of the left ventricle and examined with regards to right ventricular size and function as well as clinical variables. RESULTS: In this study, patients with chronic pulmonary hypertension had statistically different right ventricular fractional area change (35 ± 13 percent), right ventricular end-systolic area (21 ± 10 cm(2)), right ventricular Myocardial Performance Index (0.72 ± 0.34), and Eccentricity Index (1.34 ± 0.37) than individuals without pulmonary hypertension (51 ± 5 percent, 9 ± 2 cm(2), 0.27 ± 0.09, and 0.97 ± 0.06, p < 0.005, respectively). Furthermore, peak longitudinal right ventricular wall strain in chronic pulmonary hypertension was also different -20.8 ± 9.0 percent versus -28.0 ± 4.1 percent, p < 0.01). Right ventricular dyssynchrony correlated very well with right ventricular end-systolic area (r = 0.79, p < 0.001) and Eccentricity Index (r = 0.83, p < 0.001). Furthermore, right ventricular dyssynchrony correlates with pulmonary hypertension severity index (p < 0.0001), World Health Organization class (p < 0.0001), and number of hospitalizations (p < 0.0001). CONCLUSION: Lower peak longitudinal right ventricular wall strain and significantly delayed time-to-peak strain values, consistent with right ventricular dyssynchrony, were found in a small heterogeneous group of patients with chronic pulmonary hypertension when compared to individuals without pulmonary hypertension. Furthermore, right ventricular dyssynchrony was associated with disease severity and compromised functional class

Intravitreal bevacizumab in diabetic retinopathy. Recommendations from the Pan-American Collaborative Retina Study Group (PACORES): The 2016 knobloch lecture

The advent of intravitreal anti-vascular endothelial growth factor (anti-VEGF) medications has revolutionized the treatment of diabetic eye diseases. Herein, we report the outcomes of clinical studies carried out by the Pan-American Collaborative Retina Study Group (PACORES), with a specific focus on the efficacy of intravitreal bevacizumab in the management of diabetic macular edema and proliferative diabetic retinopathy. We will also discuss the use of intravitreal bevaci-zumab as a preoperative, adjuvant therapy before vitrectomy for prolif-erative diabetic retinopathy. Copyright © 2017 by Asia Pacific Academy of Ophthalmology

Investigating Cytochrome P450 specificity during glycopeptide antibiotic biosynthesis through a homologue hybridization approach

Cytochrome P450 enzymes perform an impressive range of oxidation reactions against diverse substrate scaffolds whilst generally maintaining a conserved tertiary structure and active site chemistry. Within secondary metabolism, P450 enzymes play widespread and important roles in performing crucial modifications of precursor molecules, with one example of the importance of such reactions being found in the biosynthesis of the glycopeptide antibiotics (GPAs). In GPA biosynthesis P450s, known as Oxy enzymes, are key players in the cyclization of the linear GPA peptide precursor, which is a process that is both essential for their antibiotic activity and is the source of the synthetic challenge of these important antibiotics. In this work, we developed chimeric P450 enzymes from GPA biosynthesis based on two homologues from different GPA biosynthesis pathways – vancomycin and teicoplanin – as an approach to explore the divergent catalytic behavior of the two parental homologues. We could generate, crystalize and explore the activity of new hybrid P450 enzymes from GPA biosynthesis and show that the unusual in vitro behavior of the vancomycin OxyB homologue does not stem from the major regions of the P450 active site, and that additional regions in and around the P450 active site must contribute to the unusual properties of this P450 enzyme. Our results further show that it is possible to successfully transplant entire regions of secondary structure between such P450s and retain P450 expression and activity, which opens the door to use such targeted approaches to generate and explore novel biosynthetic P450 enzymes

Cytochrome P450 OxyBtei catalyzes the first phenolic coupling step in teicoplanin biosynthesis

Bacterial cytochrome P450s form a remarkable clade of the P450 superfamily of oxidative hemoproteins, and are often involved in the biosynthesis of complex natural products. Those in a subgroup known as "Oxy enzymes" play a crucial role in the biosynthesis of glycopeptide antibiotics, including vancomycin and teicoplanin. The Oxy enzymes catalyze crosslinking of aromatic residues in the non-ribosomal antibiotic precursor peptide while it remains bound to the non-ribosomal peptide synthetase (NRPS); this crosslinking secures the three-dimensional structure of the glycopeptide, crucial for antibiotic activity. We have characterized OxyBtei , the first of the Oxy enzymes in teicoplanin biosynthesis. Our results reveal that OxyBtei possesses a structure similar to those of other Oxy proteins and is active in crosslinking NRPS-bound peptide substrates. However, OxyBtei displays a significantly altered activity spectrum against peptide substrates compared to its well-studied vancomycin homologue

3'-Nadp and 3'-Naadp - two metabolites formed by the bacterial type III effector AvrRxo1

An arsenal of effector proteins is injected by bacterial pathogens into the host cell or its vicinity to increase virulence. The commonly used top-down approaches inferring the toxic mechanism of individual effector proteins from the host's phenotype are often impeded by multiple targets of different effectors as well as by their pleiotropic effects. Here we describe our bottom-up approach, showing that the bacterial type III effector AvrRxo1 of plant pathogens is an authentic phosphotransferase that produces two novel metabolites by phosphorylating nicotinamide/nicotinic acid adenine dinucleotide at the adenosine 3′-hydroxyl group. Both products of AvrRxo1, 3′-NADP and 3′-nicotinic acid adenine dinucleotide phosphate (3′-NAADP), are substantially different from the ubiquitous co-enzyme 2′-NADP and the calcium mobilizer 2′-NAADP. Interestingly, 3′-NADP and 3′-NAADP have previously been used as inhibitors or signaling molecules but were regarded as “artificial” compounds so far. Our findings now necessitate a shift in thinking about the biological importance of 3′-phosphorylated NAD derivatives

The ng_ζ1 toxin of the gonococcal epsilon/zeta toxin/antitoxin system drains precursors for cell wall synthesis

Bacterial toxin–antitoxin complexes are emerging as key players modulating bacterial physiology as activation of toxins induces stasis or programmed cell death by interference with vital cellular processes. Zeta toxins, which are prevalent in many bacterial genomes, were shown to interfere with cell wall formation by perturbing peptidoglycan synthesis in Gram-positive bacteria. Here, we characterize the epsilon/zeta toxin–antitoxin (TA) homologue from the Gram-negative pathogen Neisseria gonorrhoeae termed ng_ɛ1 / ng_ζ1. Contrary to previously studied streptococcal epsilon/zeta TA systems, ng_ɛ1 has an epsilon-unrelated fold and ng_ζ1 displays broader substrate specificity and phosphorylates multiple UDP-activated sugars that are precursors of peptidoglycan and lipopolysaccharide synthesis. Moreover, the phosphorylation site is different from the streptococcal zeta toxins, resulting in a different interference with cell wall synthesis. This difference most likely reflects adaptation to the individual cell wall composition of Gram-negative and Gram-positive organisms but also the distinct involvement of cell wall components in virulence

Rapid access to glycopeptide antibiotic precursor peptides coupled with cytochrome P450-mediated catalysis: towards a biomimetic synthesis of glycopeptide antibiotics

Understanding the mechanisms underpinning glycopeptide antibiotic biosynthesis is key to the future ability to reinvent these compounds. For effective in vitro characterization of the crucial later steps of the biosynthesis, facile access to a wide range of substrate peptides as their Coenzyme A (CoA) conjugates is essential. Here we report the development of a rapid route to glycopeptide precursor CoA conjugates that affords both high yields and excellent purities. This synthesis route is applicable to the synthesis of peptide CoA-conjugates containing racemization-prone arylglycine residues: such residues are hallmarks of non-ribosomal peptide synthesis and have previously been inaccessible to peptide synthesis using Fmoc-type chemistry. We have applied this route to generate glycopeptide precursor peptides in their carrier protein-bound form as substrates to explore the specificity of the first oxygenase enzyme from vancomycin biosynthesis (OxyBvan). Our results indicate that OxyBvan is a highly promiscuous catalyst for phenolic coupling of diverse glycopeptide precursors that accepts multiple carrier protein substrates, even on carrier protein domains from alternate glycopeptide biosynthetic machineries. These results represent the first important steps in the development of an in vitro biomimetic synthesis of modified glycopeptide aglycone