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Molecular Genetics and Metabolism Jan 2021Neonatal onset Urea cycle disorders (UCDs) can be life threatening with severe hyperammonemia and poor neurological outcomes. Glycerol phenylbutyrate (GPB) is safe and...
BACKGROUND/AIMS
Neonatal onset Urea cycle disorders (UCDs) can be life threatening with severe hyperammonemia and poor neurological outcomes. Glycerol phenylbutyrate (GPB) is safe and effective in reducing ammonia levels in patients with UCD above 2 months of age. This study assesses safety, ammonia control and pharmacokinetics (PK) of GPB in UCD patients below 2 months of age.
METHODS
This was an open-label study in UCD patients aged 0 - 2 months, consisting of an initiation/transition period (1 - 4 days) to GPB, followed by a safety extension period (6 months to 2 years). Patients presenting with a hyperammonemic crisis (HAC) did not initiate GPB until blood ammonia levels decreased to below 100 µmol/L while receiving sodium phenylacetate/sodium benzoate and/or hemodialysis. Ammonia levels, PK analytes and safety were evaluated during transition and monthly during the safety extension for 6 months and every 3 months thereafter.
RESULTS
All 16 patients with UCD (median age 0.48 months, range 0.1 to 2.0 months) successfully transitioned to GPB within 3 days. Average plasma ammonia level excluding HAC was 94.3 µmol/L at baseline and 50.4 µmol/L at the end of the transition period (p = 0.21). No patient had a HAC during the transition period. During the safety extension, the majority of patients had controlled ammonia levels, with mean plasma ammonia levels lower during GPB treatment than baseline. Mean glutamine levels remained within normal limits throughout the study. PK analyses indicate that UCD patients <2 months are able to hydrolyze GPB with subsequent absorption of phenylbutyric acid (PBA), metabolism to phenylacetic acid (PAA) and conjugation with glutamine. Plasma concentrations of PBA, PAA, and phenylacetylglutamine (PAGN) were stable during the safety extension phase and mean plasma phenylacetic acid: phenylacetylglutamine ratio remained below 2.5 suggesting no accumulation of GPB. All patients reported at least 1 treatment emergent adverse event with gastroesophageal reflux disease, vomiting, hyperammonemia, diaper dermatitis (37.5% each), diarrhea, upper respiratory tract infection and rash (31.3% each) being the most frequently reported.
CONCLUSIONS
This study supports safety and efficacy of GPB in UCD patients aged 0 -2 months who cannot be managed by dietary protein restriction and/or amino acid supplementation alone. GPB undergoes intestinal hydrolysis with no accumulation in this population.
Topics: Age of Onset; Ammonia; Child, Preschool; Female; Glycerol; Humans; Hyperammonemia; Infant; Infant, Newborn; Male; Pediatrics; Phenylacetates; Phenylbutyrates; Renal Dialysis; Urea Cycle Disorders, Inborn
PubMed: 33388234
DOI: 10.1016/j.ymgme.2020.12.002 -
British Journal of Clinical Pharmacology 19801. The haemodynamic mechanism of action of guanfacine 4 mg intravenously was investigated in resting conditions and during exercise for up to 20 h after administration... (Clinical Trial)
Clinical Trial
1. The haemodynamic mechanism of action of guanfacine 4 mg intravenously was investigated in resting conditions and during exercise for up to 20 h after administration of the drug. Cardiac output and pulmonary arterial pressure were determined by the Swan-Ganz thermodilution method. Blood pressure was measured directly. 2. During and immediately after intravenous administration of guanfacine, blood pressure peripheral resistance and pulmonary arterial pressure increased (in keeping with an alpha-sympathomimetic effect of the compound), whereas heart rate and cardiac output decreased. 3. Subsequently blood pressure fell as a result of a decrease in cardiac output. From the third hour peripheral resistance decreased, whereas cardiac output increased again, sometimes exceeding the control value. 4. During exercise blood pressure was reduced from the third hour after administration, as in resting conditions, as a result of the reduction in peripheral resistance. 5. In resting conditions guanfacine reduced heart rate at the beginning and during the whole course after administration of the drug. 6. Side-effects noted included fatigue, drowsiness and bradycardia.
Topics: Antihypertensive Agents; Blood Pressure; Cardiac Output; Clinical Trials as Topic; Guanfacine; Guanidines; Hemodynamics; Humans; Hypertension; Phenylacetates; Physical Exertion; Stroke Volume; Time Factors; Vascular Resistance
PubMed: 6994766
DOI: 10.1111/j.1365-2125.1980.tb04919.x -
Journal of Bacteriology Aug 2020is an etiological agent for antibiotic-associated diarrheal disease. produces a phenolic compound, -cresol, which selectively targets gammaproteobacteria in the gut,...
is an etiological agent for antibiotic-associated diarrheal disease. produces a phenolic compound, -cresol, which selectively targets gammaproteobacteria in the gut, facilitating dysbiosis. decarboxylates -hydroxyphenylacetate (-HPA) to produce -cresol by the action of the HpdBCA decarboxylase encoded by the operon. Here, we investigate regulation of the operon and directly compare three independent reporter systems; SNAP-tag, glucuronidase , and alkaline phosphatase reporters to detect basal and inducible expression. We show that expression of is upregulated in response to elevated -HPA. analysis identified three putative promoters upstream of operon-P, P, and Pσ; only the P promoter was responsible for both basal and -HPA-inducible expression of We demonstrated that turnover of tyrosine, a precursor for -HPA, is insufficient to induce expression of the operon above basal levels because it is inefficiently converted to -HPA in minimal media. We show that induction of the operon in response to -HPA occurs in a dose-dependent manner. We also identified an inverted palindromic repeat (AAAAAG-N-CTTTTT) upstream of the start codon (ATG) that is essential for inducing transcription of the operon in response to -HPA, which drives the production of -cresol. This provides insights into the regulatory control of -cresol production, which affords a competitive advantage for over other intestinal bacteria, promoting dysbiosis. infection results from antibiotic-associated dysbiosis. -Cresol, a phenolic compound produced by , selectively targets gammaproteobacteria in the gut, facilitating dysbiosis. Here, we demonstrate that expression of the operon, encoding the HpdBCA decarboxylase which converts -HPA to -cresol, is upregulated in response to elevated exogenous -HPA, with induction occurring between >0.1 and ≤0.25 mg/ml. We determined a single promoter and an inverted palindromic repeat responsible for basal and -HPA-inducible expression. We identified turnover of tyrosine, a -HPA precursor, does not induce expression above basal level, indicating that exogenous -HPA was required for -cresol production. Identifying regulatory controls of -cresol production will provide novel therapeutic targets to prevent -cresol production, reducing 's competitive advantage.
Topics: Bacterial Proteins; Carboxy-Lyases; Clostridioides difficile; Cresols; Gene Expression Regulation, Bacterial; Operon; Phenylacetates; Promoter Regions, Genetic
PubMed: 32631945
DOI: 10.1128/JB.00282-20 -
Clinical and Translational Science Jun 2022Hepatic encephalopathy (HE) is a serious neurocognitive complication of liver dysfunction, often associated with elevated plasma ammonia. Ornithine phenylacetate (OP), a... (Randomized Controlled Trial)
Randomized Controlled Trial
Pharmacokinetics/pharmacodynamics of L-ornithine phenylacetate in overt hepatic encephalopathy and the effect of plasma ammonia concentration reduction on clinical outcomes.
Hepatic encephalopathy (HE) is a serious neurocognitive complication of liver dysfunction, often associated with elevated plasma ammonia. Ornithine phenylacetate (OP), a potent ammonia scavenger, is being evaluated for the treatment of acute/overt HE. The pharmacokinetics and pharmacodynamics of OP in patients with HE were characterized in this phase IIb study (NCT01966419). Adult patients hospitalized with an overt HE episode, cirrhosis, and plasma ammonia above the upper limit of normal (ULN) who failed to improve after 48 hours' standard care were randomly assigned to continuous intravenous OP (10, 15, or 20 g/day, based on Child-Turcotte-Pugh score) or matching placebo for 5 days. Plasma levels of ornithine and phenylacetic acid (PAA) and plasma/urinary levels of phenylacetylglutamine (PAGN) (primary metabolite of PAA) were regularly assessed; plasma ammonia level was the primary pharmacodynamic variable. PAA demonstrated dose-dependent pharmacokinetics; ornithine and PAGN levels increased with dose. PAGN urinary excretion represented ~50%-60% of administered PAA across all doses. Mean reduction in plasma ammonia with OP at 3 hours postinfusion was significantly greater versus placebo (p = 0.014); and time to achieve plasma ammonia less than or equal to the ULN was significantly reduced (p = 0.028). Achievement of clinical response based on HE stage was associated with a greater reduction in mean plasma ammonia level (p = 0.009). OP effects on plasma ammonia were consistent with its proposed mechanism of action as a primary ammonia scavenger, with a significant association between reduced plasma ammonia and improvement in HE stage. OP should be further evaluated as a promising treatment for hyperammonemia in patients with overt HE.
Topics: Adult; Ammonia; Hepatic Encephalopathy; Humans; Ornithine; Phenylacetates
PubMed: 35238476
DOI: 10.1111/cts.13257 -
Applied and Environmental Microbiology Aug 2001The antifungal substances SH-1 and SH-2 were isolated from Streptomyces humidus strain S5-55 cultures by various purification procedures and identified as phenylacetic...
The antifungal substances SH-1 and SH-2 were isolated from Streptomyces humidus strain S5-55 cultures by various purification procedures and identified as phenylacetic acid and sodium phenylacetate, respectively, based on the nuclear magnetic resonance, electron ionization mass spectral, and inductively coupled plasma mass spectral data. SH-1 and SH-2 completely inhibited the growth of Pythium ultimum, Phytophthora capsici, Rhizoctonia solani, Saccharomyces cerevisiae, and Pseudomonas syringae pv. syringae at concentrations from 10 to 50 microg/ml. The two compounds were as effective as the commercial fungicide metalaxyl in inhibiting spore germination and hyphal growth of P. capsici. However, the in vivo control efficacies of the two antifungal compounds against P. capsici infection on pepper plants were similar to those of H(3)PO(3) and fosetyl-AI but less than that of metalaxyl.
Topics: Antifungal Agents; Capsicum; Culture Media, Conditioned; Fungi; Microbial Sensitivity Tests; Oomycetes; Phenylacetates; Plant Diseases; Plants, Medicinal; Streptomyces
PubMed: 11472958
DOI: 10.1128/AEM.67.8.3739-3745.2001 -
International Journal of Molecular... Jun 2020Tendinopathy is a rare but serious complication of quinolone therapy. Risk factors associated with quinolone-induced tendon disorders include chronic kidney disease... (Comparative Study)
Comparative Study
Tendinopathy is a rare but serious complication of quinolone therapy. Risk factors associated with quinolone-induced tendon disorders include chronic kidney disease accompanied by the accumulation of uremic toxins. Hence, the present study explored the effects of the representative uremic toxins phenylacetic acid (PAA) and quinolinic acid (QA), both alone and in combination with ciprofloxacin (CPX), on human tenocytes in vitro. Tenocytes incubated with uremic toxins +/- CPX were investigated for metabolic activity, vitality, expression of the dominant extracellular tendon matrix (ECM) protein type I collagen, cell-matrix receptor β1-integrin, proinflammatory interleukin (IL)-1β, and the ECM-degrading enzyme matrix metalloproteinase (MMP)-1. CPX, when administered at high concentrations (100 mM), suppressed tenocyte metabolism after 8 h exposure and at therapeutic concentrations after 72 h exposure. PAA reduced tenocyte metabolism only after 72 h exposure to very high doses and when combined with CPX. QA, when administered alone, led to scarcely any cytotoxic effect. Combinations of CPX with PAA or QA did not cause greater cytotoxicity than incubation with CPX alone. Gene expression of the pro-inflammatory cytokine IL-1β was reduced by CPX but up-regulated by PAA and QA. Protein levels of type I collagen decreased in response to high CPX doses, whereas PAA and QA did not affect its synthesis significantly. MMP-1 mRNA levels were increased by CPX. This effect became more pronounced in the form of a synergism following exposure to a combination of CPX and PAA. CPX was more tenotoxic than the uremic toxins PAA and QA, which showed only distinct suppressive effects.
Topics: Adult; Cell Survival; Cells, Cultured; Ciprofloxacin; Collagen Type I; Female; Gene Expression Regulation; Humans; Interleukin-1beta; Male; Matrix Metalloproteinase 1; Phenylacetates; Quinolinic Acid; Tenocytes
PubMed: 32545914
DOI: 10.3390/ijms21124241 -
Chemical & Pharmaceutical Bulletin Aug 2021Amide bond formation is one of the most fundamental reactions in organic chemistry, and amide bonds constitute the key functional groups in natural products, peptides,...
Amide bond formation is one of the most fundamental reactions in organic chemistry, and amide bonds constitute the key functional groups in natural products, peptides, and pharmaceuticals. Here we demonstrate the chemoenzymatic syntheses of 4-coumaroyl- and hexanoyl-amino acids, using 4-coumarate: CoA ligase from the model plant Arabidopsis thaliana (At4CL2). At4CL2 accepts 4-coumaric acid and hexanoic acid as the carboxylate substrates to generate acyl adenylates, which are captured by the amino group of amino acids to afford a series of N-acyl amides. This study shows the potential of 4CL for application as a biocatalyst to generate a series of biologically active amide compounds.
Topics: Amides; Amino Acids; Arabidopsis; Benzoic Acid; Biocatalysis; Caproates; Coenzyme A; Coumaric Acids; Ligases; Molecular Structure; Phenylacetates
PubMed: 34053981
DOI: 10.1248/cpb.c21-00404 -
Molecular Genetics and Metabolism Nov 2012We have analyzed pharmacokinetic data for glycerol phenylbutyrate (also GT4P or HPN-100) and sodium phenylbutyrate with respect to possible dosing biomarkers in patients... (Randomized Controlled Trial)
Randomized Controlled Trial
UNLABELLED
We have analyzed pharmacokinetic data for glycerol phenylbutyrate (also GT4P or HPN-100) and sodium phenylbutyrate with respect to possible dosing biomarkers in patients with urea cycle disorders (UCD).
STUDY DESIGN
These analyses are based on over 3000 urine and plasma data points from 54 adult and 11 pediatric UCD patients (ages 6-17) who participated in three clinical studies comparing ammonia control and pharmacokinetics during steady state treatment with glycerol phenylbutyrate or sodium phenylbutyrate. All patients received phenylbutyric acid equivalent doses of glycerol phenylbutyrate or sodium phenylbutyrate in a cross over fashion and underwent 24-hour blood samples and urine sampling for phenylbutyric acid, phenylacetic acid and phenylacetylglutamine.
RESULTS
Patients received phenylbutyric acid equivalent doses of glycerol phenylbutyrate ranging from 1.5 to 31.8 g/day and of sodium phenylbutyrate ranging from 1.3 to 31.7 g/day. Plasma metabolite levels varied widely, with average fluctuation indices ranging from 1979% to 5690% for phenylbutyric acid, 843% to 3931% for phenylacetic acid, and 881% to 1434% for phenylacetylglutamine. Mean percent recovery of phenylbutyric acid as urinary phenylacetylglutamine was 66.4 and 69.0 for pediatric patients and 68.7 and 71.4 for adult patients on glycerol phenylbutyrate and sodium phenylbutyrate, respectively. The correlation with dose was strongest for urinary phenylacetylglutamine excretion, either as morning spot urine (r = 0.730, p < 0.001) or as total 24-hour excretion (r = 0.791 p<0.001), followed by plasma phenylacetylglutamine AUC(24-hour), plasma phenylacetic acid AUC(24-hour) and phenylbutyric acid AUC(24-hour). Plasma phenylacetic acid levels in adult and pediatric patients did not show a consistent relationship with either urinary phenylacetylglutamine or ammonia control.
CONCLUSION
The findings are collectively consistent with substantial yet variable pre-systemic (1st pass) conversion of phenylbutyric acid to phenylacetic acid and/or phenylacetylglutamine. The variability of blood metabolite levels during the day, their weaker correlation with dose, the need for multiple blood samples to capture trough and peak, and the inconsistency between phenylacetic acid and urinary phenylacetylglutamine as a marker of waste nitrogen scavenging limit the utility of plasma levels for therapeutic monitoring. By contrast, 24-hour urinary phenylacetylglutamine and morning spot urine phenylacetylglutamine correlate strongly with dose and appear to be clinically useful non-invasive biomarkers for compliance and therapeutic monitoring.
Topics: Adolescent; Adult; Ammonia; Biomarkers, Pharmacological; Child; Cross-Over Studies; Drug Administration Schedule; Female; Glutamine; Glycerol; Humans; Male; Phenylacetates; Phenylbutyrates; Urea Cycle Disorders, Inborn
PubMed: 22958974
DOI: 10.1016/j.ymgme.2012.08.006 -
American Journal of Human Genetics Nov 1983The heterozygous human serum paraoxonase phenotype can be clearly distinguished from both homozygous phenotypes on the basis of its distinctive ratio of paraoxonase to...
The heterozygous human serum paraoxonase phenotype can be clearly distinguished from both homozygous phenotypes on the basis of its distinctive ratio of paraoxonase to arylesterase activities. A trimodal distribution of the ratio values was found with 348 individual serum samples, measuring the ratio of paraoxonase activity (with 1 M NaCl in the assay) to arylesterase activity, using phenylacetate. The three modes corresponded to the three paraoxonase phenotypes, A, AB, and B (individual genotypes), and the expected Mendelian segregation of the trait was observed within families. The paraoxonase/arylesterase activity ratio showed codominant inheritance. We have defined the genetic locus determining the aromatic esterase (arylesterase) responsible for the polymorphic paraoxonase activity as esterase-A (ESA) and have designated the two common alleles at this locus by the symbols ESA*A and ESA*B. The frequency of the ESA*A allele was estimated to be .685, and that of the ESA*B allele, 0.315, in a sample population of unrelated Caucasians from the United States. We postulate that a single serum enzyme, with both paraoxonase and arylesterase activity, exists in two different isozymic forms with qualitatively different properties, and that paraoxon is a "discriminating" substrate (having a polymorphic distribution of activity) and phenylacetate is a "nondiscriminating" substrate for the two isozymes. Biochemical evidence for this interpretation includes the cosegregation of the degree of stimulation of paraoxonase activity by salt and paraoxonase/arylesterase activity ratio characteristics; the very high correlation between both the basal (non-salt stimulated) and salt-stimulated paraoxonase activities with arylesterase activity; and the finding that phenylacetate is an inhibitor for paraoxonase activities in both A and B types of enzyme.
Topics: Adolescent; Adult; Aryldialkylphosphatase; Female; Gene Frequency; Genes; Heterozygote; Homozygote; Humans; Isoenzymes; Male; Middle Aged; Paraoxon; Pedigree; Phenotype; Phenylacetates; Phosphoric Monoester Hydrolases; Polymorphism, Genetic; Substrate Specificity
PubMed: 6316781
DOI: No ID Found -
Nature Chemical Biology Jun 2018The soil microbiome can produce, resist, or degrade antibiotics and even catabolize them. While resistance genes are widely distributed in the soil, there is a dearth of...
The soil microbiome can produce, resist, or degrade antibiotics and even catabolize them. While resistance genes are widely distributed in the soil, there is a dearth of knowledge concerning antibiotic catabolism. Here we describe a pathway for penicillin catabolism in four isolates. Genomic and transcriptomic sequencing revealed β-lactamase, amidase, and phenylacetic acid catabolon upregulation. Knocking out part of the phenylacetic acid catabolon or an apparent penicillin utilization operon (put) resulted in loss of penicillin catabolism in one isolate. A hydrolase from the put operon was found to degrade in vitro benzylpenicilloic acid, the β-lactamase penicillin product. To test the generality of this strategy, an Escherichia coli strain was engineered to co-express a β-lactamase and a penicillin amidase or the put operon, enabling it to grow using penicillin or benzylpenicilloic acid, respectively. Elucidation of additional pathways may allow bioremediation of antibiotic-contaminated soils and discovery of antibiotic-remodeling enzymes with industrial utility.
Topics: Amidohydrolases; Burkholderia; Cloning, Molecular; Gene Expression Regulation, Bacterial; Genome; Hydrolases; Microbial Sensitivity Tests; Microbiota; Open Reading Frames; Operon; Penicillins; Phenylacetates; Phylogeny; Pseudomonas; Soil; Soil Microbiology; Transcriptome; Up-Regulation; beta-Lactamases; beta-Lactams
PubMed: 29713061
DOI: 10.1038/s41589-018-0052-1