This case series describes the proportion of awake, nonintubated inpatients with COVID-19 and hypoxemic respiratory failure requiring oxygen supplementation whose Pa
o
2
increased ≥20% with prone ...positioning, and their respiratory status after resuming supine positioning.
Prone positioning reduces mortality in the management of intubated patients with moderate-to-severe acute respiratory distress syndrome. It allows improvement in oxygenation by improving ...ventilation/perfusion ratio mismatching.Because of its positive physiological effects, prone positioning has also been tested in non-intubated, spontaneously breathing patients, or "awake" prone positioning. This review provides an update on awake prone positioning for hypoxaemic respiratory failure, in both coronavirus disease 2019 (COVID-19) and non-COVID-19 patients. In non-COVID-19 acute respiratory failure, studies are limited to a few small nonrandomised studies and involved patients with different diseases. However, results have been appealing with regard to oxygenation improvement, especially when combined with noninvasive ventilation or high-flow nasal cannula.The recent COVID-19 pandemic has led to a major increase in hospitalisations for acute respiratory failure. Awake prone positioning has been used with the aim to prevent intensive care unit admission and mechanical ventilation. Prone positioning in conscious, non-intubated COVID-19 patients is used in emergency departments, medical wards and intensive care units.Several trials reported an improvement in oxygenation and respiratory rate during prone positioning, but impacts on clinical outcomes, particularly on intubation rates and survival, remain unclear. Tolerance of prolonged prone positioning is an issue. Larger controlled, randomised studies are underway to provide results concerning clinical benefit and define optimised prone positioning regimens.
Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium verticillioides (formerly F. moniliforme), a fungus that commonly contaminates maize. FB1 causes toxicological effects in laboratory and ...domestic animals including pigs. Because the gastrointestinal tract represents the first barrier met by exogenous food compounds, the purpose of this study was to investigate the effects of FB1 on IPEC-1, a porcine intestinal epithelial cell line. We first verified that low concentrations of FB1 did not exert any cytotoxic effect on IPEC-1. Indeed, significant LDH release was only observed for FB1 concentrations greater than 50 and 700 μM on proliferating and nonproliferating cells, respectively. We then demonstrated that FB1 inhibits proliferation of IPEC-1. Fluorescence-activated cell sorting (FACS) analysis of the cell cycle indicated that FB1 blocks the proliferation of intestinal cells in the G0/G1 phase. Similar results were obtained with LLC-PK1, a renal porcine epithelial cell line, which is considered to be a good model for studying FB1 in vitro effects. We have also assessed the effects of FB1 on the integrity of the barrier formed by the intestinal epithelium. We demonstrated that FB1 decreases the transepithelial electrical resistance (TEER) of IPEC-1 in a time- and dose-dependent manner. This effect was only noticed after a long exposure (8–12 days of treatment). FB1 induced the TEER decrease independently of the cell differentiation stage, and this effect was partially reversible. Taken together, our data indicate that FB1 alters the proliferation and the barrier function of intestinal cells. These results may have implications for humans and animals consuming FB1-contaminated food or feed.
Exposure to tobacco smoke has been not evaluated in children with bronchopulmonary dysplasia (BPD). We evaluate the association of in utero smoking (IUS) and environmental tobacco smoke (ETS) with ...the respiratory events of BPD and non-BPD children. Two hundred sixty-two children born before 35 weeks of gestational age (GA) and regularly followed up in our regional network for preterms were enrolled. They were paired according to their BPD status, their gestational age and birth weight (131 children with BPD and 131 without BPD, 28 mean weeks GA; mean weight 1000 g). Respiratory data were obtained prospectively during their first 2 years of life. A complementary questionnaire was completed by the parents about their child’s respiratory health at the age of 2, their home environment, and tobacco status. IUS concerned 12.6 %; ETS, 48.8 % (67 % in BPD children treated with oxygen at home). No further influence on respiratory outcome could be found by exposure to intrauterine smoke or extrauterine tobacco smoke in this patient sample.
Conclusion
: IUS and ETS exposures are as high in preterm children as in a general pediatric population. The highest exposure occurs among BPD infants treated with oxygen at home.
What is known:
•
Environmental tobacco smoke (ETS) and in utero smoking (IUS) are responsible for many morphological, functional, and clinical changes in children.
•
Children with bronchopulmonary dysplasia (BPD) have more respiratory events in their first years of life than preterm children without BPB, maybe triggered by ETS and IUS.
What is New:
•
The exposition to ETS and IUS is high in preterm children with and without BDP, as high as in a general.
•
Pedaitric population, particularly in children with BPD and treated with oxygen at home.
•
No further influence on respiratory outcome could be found by exposure to ETS or IUS in our studied population.
Greyhounds metabolize cytochrome P450 (CYP) 2B11 substrates more slowly than other dog breeds. However, CYP2B11 gene variants associated with decreased CYP2B11 expression do not fully explain reduced ...CYP2B11 activity in this breed. P450 oxidoreductase (POR) is an essential redox partner for all CYPs. POR protein variants can enhance or repress CYP enzyme function in a CYP isoform and substrate dependent manner. The study objectives were to identify POR protein variants in greyhounds and determine their effect on coexpressed CYP2B11 and CYP2D15 enzyme function. Gene sequencing identified two missense variants (Glu315Gln and Asp570Glu) forming four alleles, POR-H1 (reference), POR-H2 (570Glu), POR-H3 (315Gln, 570Glu) and POR-H4 (315Gln). Out of 68 dog breeds surveyed, POR-H2 was widely distributed across multiple breeds, while POR-H3 was largely restricted to greyhounds and Scottish deerhounds (35% allele frequencies), and POR-H4 was rare. Three-dimensional protein structure modelling indicated significant effects of Glu315Gln (but not Asp570Glu) on protein flexibility through loss of a salt bridge between Glu315 and Arg519. Recombinant POR-H1 (reference) and each POR variant (H2-H4) were expressed alone or with CYP2B11 or CYP2D15 in insect cells. No substantial effects on POR protein expression or enzyme activity (cytochrome c reduction) were observed for any POR variant (versus POR-H1) when expressed alone or with CYP2B11 or CYP2D15. Furthermore, there were no effects on CYP2B11 or CYP2D15 protein expression, or on CYP2D15 enzyme kinetics by any POR variant (versus POR-H1). However, Vmax values for 7-benzyloxyresorufin, propofol and bupropion oxidation by CYP2B11 were significantly reduced by coexpression with POR-H3 (by 34-37%) and POR-H4 (by 65-72%) compared with POR-H1. Km values were unaffected. Our results indicate that the Glu315Gln mutation (common to POR-H3 and POR-H4) reduces CYP2B11 enzyme function without affecting at least one other major canine hepatic P450 (CYP2D15). Additional in vivo studies are warranted to confirm these findings.
Develop a cytochrome P450 (CYP) phenotyping cocktail for dogs using specific substrates for hepatic P450 enzymes CYP2B11, CYP2D15, and CYP3A12 and determine whether alternative sampling methods ...(saliva and urine) or single time point samples could be used instead of multiple blood sampling.
12 healthy client-owned dogs (8 females and 4 males) from February 2019 to May 2019.
In a randomized crossover study, dogs received oral administration of the probe drug bupropion (75 mg), dextromethorphan (30 mg), or omeprazole (40 mg) alone or as a 3-drug combination (Program in Individualized Medicine PrIMe cocktail) to evaluate simultaneous phenotyping of CYP2B11, CYP2D15, and CYP3A12. Pharmacokinetic profiles for the probe drugs and metabolites were determined using plasma, saliva, and urine. Dogs received probe drugs alone or combined. Pharmacokinetic profiles up to 6 hours postdose for the probe drugs and metabolites were determined using plasma, saliva, and urine.
The PrIMe cocktail was well tolerated. There was no statistically significant interaction between the probe drugs when administered together. Single time point plasma metabolic ratios at 4 hours postdose for all probe drugs strongly correlated with the corresponding area under the plasma concentration-versus-time curve (AUC) ratios. Saliva AUC metabolic ratios for CYP3A12 and CYP2D15 and 6-hour urine for CYP2B11 and CYP2D15 were correlated with plasma AUC ratios.
The PrIMe cocktail can be used for simultaneous CYP phenotyping using plasma 4-hour single time point sample metabolic ratios. Saliva and urine sampling are suitable for specific CYPs.
The PrIMe cocktail has potential as a useful tool in dogs to detect clinically important CYP-mediated drug-drug interactions, identify novel pharmacogenes, determine the drug-metabolizing phenotype of individual dogs, aid in individualized dose selection, and evaluate the effects of various physiological states on drug metabolism.
Greyhounds recover more slowly from certain injectable anesthetics than other dog breeds. Previous studies implicate cytochrome P450 (CYP) 2B11 as an important clearance mechanism for these drugs and ...suggest Greyhounds are deficient in CYP2B11. However, no CYP2B11 gene mutations have been identified that explain this deficiency in Greyhounds. The objectives of this study were to provide additional evidence for CYP2B11 deficiency in Greyhounds, determine the mechanisms underlying this deficiency, and identify CYP2B11 mutations that contribute to this phenotype in Greyhounds. Greyhound livers metabolized CYP2B11 substrates slower, possessed lower CYP2B11 protein abundance, but had similar or higher mRNA expression than other breeds. Gene resequencing identified three CYP2B11 haplotypes, H1 (reference), H2, and H3 that were differentiated by mutations in the gene 3'-untranslated region (3'-UTR). Compared with 63 other dog breeds, Greyhounds had the highest CYP2B11-H3 allele frequency, while CYP2B11-H2 was widely distributed across most breeds. Using 3'-UTR luciferase reporter constructs, CYP2B11-H3 showed markedly lower gene expression (over 70%) compared to CYP2B11-H1 while CYP2B11-H2 expression was intermediate. Truncated mRNA transcripts were observed in CYP2B11-H2 and CYP2B11-H3 but not CYP2B11-H1 transfected cells. Our results implicate CYP2B11 3'-UTR mutations as a cause of decreased CYP2B11 enzyme expression in Greyhounds through reduced translational efficiency.
Dogs are commonly used in human and veterinary pharmaceutical development. Physiologically based pharmacokinetic modeling using recombinant cytochrome P450 (CYP) enzymes requires accurate estimates ...of CYP abundance, particularly in liver. However, such estimates are currently available for only seven CYPs, which were determined in a limited number of livers from one dog breed (beagle). In this study, we used a label-free shotgun proteomics method to quantitate 11 CYPs (including four CYPs not previously measured), cytochrome P450 oxidoreductase, and cytochrome b5 in liver microsomes from 59 dogs representing four different breeds and mixed-breed dogs. Validation included showing correlation with CYP marker activities, immunoquantified protein, as well as CYP1A2 and CYP2C41 null allele genotypes. Abundance values largely agreed with those previously published. Average CYP abundance was highest (>120 pmol/mg protein) for CYP2D15 and CYP3A12; intermediate (40-89 pmol/mg) for CYP1A2, CYP2B11, CYP2E1, and CYP2C21; and lowest (<12 pmol/mg) for CYP2A13, CYP2A25, CYP2C41, CYP3A26, and CYP1A1. The CYP2C41 gene was detected in 12 of 58 (21%) livers. CYP2C41 protein abundance averaged 8.2 pmol/mg in those livers, and was highest (19 pmol/mg) in the only liver with two CYP2C41 gene copies. CYP1A2 protein was not detected in the only liver homozygous for the CYP1A2 stop codon mutation. Large breed-associated differences were observed for CYP2B11 (
< 0.0001; ANOVA) but not for other CYPs. Research hounds and Beagles had the highest CYP2B11 abundance; mixed-breed dogs and Chihuahua were intermediate; whereas greyhounds had the lowest abundance. These results provide the most comprehensive estimates to date of CYP abundance and variability in canine liver. SIGNIFICANCE STATEMENT: This work provides the most comprehensive quantitative analysis to date of the drug-metabolizing cytochrome P450 proteome in dogs that will serve as a valuable reference for physiologically based scaling and modeling used in drug development and research. This study also revealed high interindividual variation and dog breed-associated differences in drug-metabolizing cytochrome P450 expression that may be important for predicting drug disposition variability among a genetically diverse canine population.
Abstract
Karrikins (KARs) are chemicals in smoke that can enhance germination of many plants. Lettuce (Lactuca sativa) cv. Grand Rapids germinates in response to nanomolar karrikinolide (KAR1). ...Lettuce is much less responsive to KAR2 or a mixture of synthetic strigolactone analogs, rac-GR24. We investigated the molecular basis of selective and sensitive KAR1 perception in lettuce. The lettuce genome contains two copies of KARRIKIN INSENSITIVE2 (KAI2), which in Arabidopsis (Arabidopsis thaliana) encodes a receptor that is required for KAR responses. LsKAI2b is more highly expressed than LsKAI2a in dry achenes and during early stages of imbibition. Through cross-species complementation assays in Arabidopsis, we found that an LsKAI2b transgene confers robust responses to KAR1, but LsKAI2a does not. Therefore, LsKAI2b likely mediates KAR1 responses in lettuce. We compared homology models of KAI2 proteins from lettuce and a fire-follower, whispering bells (Emmenanthe penduliflora). This identified pocket residues 96, 124, 139, and 161 as candidates that influence the ligand specificity of KAI2. Further support for the importance of these residues was found through a broader comparison of pocket residues among 281 KAI2 proteins from 184 asterid species. Almost all KAI2 proteins had either Tyr or Phe identity at position 124. Genes encoding Y124-type KAI2 are more broadly distributed in asterids than in F124-type KAI2. Substitutions at residues 96, 124, 139, and 161 in Arabidopsis KAI2 produced a broad array of responses to KAR1, KAR2, and rac-GR24. This suggests that the diverse ligand preferences observed among KAI2 proteins in plants could have evolved through relatively few mutations.
Plants selectively detect germination stimulants in smoke and other butenolide chemicals as a result of evolutionary changes to the ligand-binding pocket of an enzyme-receptor protein.
PDF
