The measurement of phosphatidate phosphohydrolase in human amniotic fluid

Phosphatidate phosphohydrolase (EC 3.1.3.4) activity can be found in late gestational human amniotic fluid and is thought to originate in type II alveolar cells of the fetal lungs where it plays an important role in lung surfactant synthesis. In the present study, phosphatidate phosphohydrolase activity was detected and characterized in a 105 000 x g pellet of amniotic fluid using either [32P] phosphatidate or a water-soluble analog, 1-O-hexadecyl-rac-[2-3H]glycerol 3-phosphate as substrate. With either substrate, enzyme activity was optimal at pH 6.0. The soluble analog was hydrolyzed with a Km value of 163 [mu]M and a V of 30 nmol/min per mg of protein, and offered several advantages over phosphatidate as a substrate for assaying phosphatidate phosphohydrolase in amniotic fluid. Using the synthetic analog, phosphatidate phosphohydrolase activity was measured in the 700 x g supernatant fraction of 30 human amniocentesis samples and compared with another index of fetal lung maturity, the phosphatidylcholine/sphingomyelin ratio. The results suggest that the new phosphohydrolase assay may be clinically useful in the assessment of fetal lung development.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22628/1/0000178.pd

Echocardiographic prediction of outcome after cardiac resynchronization therapy: conventional methods and recent developments

Echocardiography plays an important role in patient assessment before cardiac resynchronization therapy (CRT) and can monitor many of its mechanical effects in heart failure patients. Encouraged by the highly variable individual response observed in the major CRT trials, echocardiography-based measurements of mechanical dyssynchrony have been extensively investigated with the aim of improving response prediction and CRT delivery. Despite recent setbacks, these techniques have continued to develop in order to overcome some of their initial flaws and limitations. This review discusses the concepts and rationale of the available echocardiographic techniques, highlighting newer quantification methods and discussing some of the unsolved issues that need to be addressed

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Use of U-73122 as an Inhibitor of Phospholipase C-Dependent Processes

1-[6-[[17[beta]-3-Methoxyestra-1,3,5(10)-trien-17-yl]amino]-hexyl]1H-pyrrole-2,5-dione (U-73122) is an aminosteroid that was identified initially as a potent inhibitor of platelet activation by receptor-specific agonists. U-73122 inhibits receptor-coupled generation of inositol 1,4,5-trisphosphate (but not cyclic AMP) and intracellular mobilization of Ca 2+ in a variety of cell types. U-73122 inhibits phosphoinositide-specific phospholipase C (PI-PLC) activity in cell-free systems, but exhibits little or no direct inhibition of phospholipases A2 and D. Structure-activity analysis revealed that the maleimide group of U-73122 is essential, but not sufficient, for inhibitory activity. The succinimide analog of U-73122 (U-73343) has negligible inhibitory activity and is a useful control compound. On the basis of information derived from the use of U-73122 in a variety of cell types, procedures for storing, dissolving, and presenting U-73122 to cells are recommended. While knowledge of the mechanism of action of U-73122 would extend the utility of this compound, U-73122 has already been employed successfully to examine PI-PLC involvement in a variety of cellular processes. The application of U-73122 in an investigation of muscarinic receptor sequestration in SK-N-SH neuroblastoma cells is illustrated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30534/1/0000166.pd