Regulation of a common amidotransferase subunit.

In Bacillus subtilis the trpX locus specifies a glutamine-binding protein designated subunit X, which forms a complex with subunit E to constitute the anthranilate synthase enzyme aggregate (EX) and subunit A to constitute the p-aminobenzoate synthase enzyme aggregate (AX). Subunit X confers upon these enzyme complexes the ability to utilize glutamine as a substrate. The trpX locus has been examined to determine its map position and control. (i) The trpX locus was found to be cotransformed with the lysS and pabA loci. The results of three-factor transformation analyses suggest the following order of these markers: lysS-sul-trpX-pabA. (ii) Mutation to constitutivity of the tryptophan operon resulted in a 50- to 60-fold increase in the level of subunit X when the mutant contained functional trE and abA gene products; however, in the absence of subunit E there was only a 4- to 5-fold increase in the glutamine-binding protein. (iii) Formation of subunit X was derepressed under conditions that allow for the derepression of the trpE and/or pabA loci. (iv) Subunit X synthesis was derepressed to a greater extent in mutants that contain a functional trpE gene product than in mutants that contain a nonsense mutation in the trpE locus. These results are consistent with the hypothesis that the trpE and pabA gene products affect the expression and control of the trpX locus.     

Properties of purified rat hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase and regulation of enzyme activity

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase from rat liver microsomes has been purified to apparent homogeneity with recoveries of approximately 50%. The enzyme obtained from rats fed a diet supplemented with cholestyramine had specific activities of approximately 21,500 nmol of NADPH oxidized/min/mg of protein. After amino acid analysis a specific activity of 31,000 nmol of NADPH oxidized/min/mg of amino acyl mass was obtained. The s20,w for HMG-CoA reductase was 6.14 S and the Stokes radius was .39 nm. The molecular weight of the enzyme was 104,000 and the enzyme subunit after sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 52,000. Antibodies prepared against the homogeneous enzyme specifically precipitated HMG-CoA reductase from crude and pure fractions of the enzyme. Incubation of rat hepatocytes for 3 h in the presence of lecithin dispersions, compactin, or rat serum resulted in significant increases in the specific activity of the microsomal bound reductase. Immunotitrations indicated that in all cases these increases were associated with an activated form of the reductase. However activation of the enzyme accounted for only a small percentage of the total increase in enzyme activity; the vast majority of the increase was apparently due to an increase in the number of enzyme molecules. In contrast, when hepatocytes were incubated with mevalonolactone the lower enzyme activity which resulted was primarily due to inactivation of the enzyme with little change in the number of enzyme molecules. Immunotitrations of microsomes obtained from rats killed at the nadir or peak of the diurnal rhythm of 3-hydroxy-3-methylglutaryl-CoA reductase indicated that the rhythm results both from enzyme activation and an increased number of reductase molecules.     

A rapid and sensitive method for the detection of histone peptides

Fluorescamine has been used to obtain a peptide map of a mixture of histones (H₃, H₂A, H₂B, and H₄) prepared from oocytes of Xenopus laevis. Fluorescamine was found to be more sensitive than o-phthalaldehyde or ninhydrin-Cd for the detection of peptide fragments obtained from tryptic digestion of oocyte histones of X. laevis and the peptic digestion of the β chain of insulin. Using the β chain of insulin for a comparison, the 8 major peptide fragments could be separated by electrophoresis within 30 min and were detectable at the picomols level. Some 70 peptide spots of X. laevis oocyte histones were resolved, thus permitting the analysis of this complex mixture of polypeptides without the need for prior separation.     

Physiologically based cord clamping for infants ≥32+0 weeks gestation: A randomised clinical trial and reference percentiles for heart rate and oxygen saturation for infants ≥35+0 weeks gestation

BackgroundGlobally, the majority of newborns requiring resuscitation at birth are full term or late-preterm infants. These infants typically have their umbilical cord clamped early (ECC) before moving to a resuscitation platform, losing the potential support of the placental circulation. Physiologically based cord clamping (PBCC) is clamping the umbilical cord after establishing lung aeration and holds promise as a readily available means of improving early newborn outcomes. In mechanically ventilated lambs, PBCC improved cardiovascular stability and reduced hypoxia. We hypothesised that PBCC compared to ECC would result in higher heart rate (HR) in infants needing resuscitation, without compromising safety.Methods and findingsBetween 4 July 2018 and 18 May 2021, infants born at ≥32⁺⁰ weeks’ gestation with a paediatrician called to attend were enrolled in a parallel-arm randomised trial at 2 Australian perinatal centres. Following initial stimulation, infants requiring further resuscitation were randomised within 60 seconds of birth using a smartphone-accessible web link. The intervention (PBCC) was to establish lung aeration, either via positive pressure ventilation (PPV) or effective spontaneous breathing, prior to cord clamping. The comparator was early cord clamping (ECC) prior to resuscitation. The primary outcome was mean HR between 60 to 120 seconds after birth, measured using 3-lead electrocardiogram, extracted from video recordings blinded to group allocation. Nonrandomised infants had deferred cord clamping (DCC) ≥120 seconds in the observational study arm.Among 508 at-risk infants enrolled, 123 were randomised (n = 63 to PBCC, n = 60 to ECC). Median (interquartile range, IQR) for gestational age was 39.9 (38.3 to 40.7) weeks in PBCC infants and 39.6 (38.4 to 40.4) weeks in ECC infants. Approximately 49% and 50% of the PBCC and ECC infants were female, respectively. Five infants (PBCC = 2, ECC = 3, 4% total) had missing primary outcome data. Cord clamping occurred at a median (IQR) of 136 (126 to 150) seconds in the PBCC arm and 37 (27 to 51) seconds in the ECC arm. Mean HR between 60 to 120 seconds after birth was 154 bpm (beats per minute) for PBCC versus 158 bpm for ECC (adjusted mean difference −6 bpm, 95% confidence interval (CI) −17 to 5 bpm, P = 0.39). Among 31 secondary outcomes, postpartum haemorrhage ≥500 ml occurred in 34% and 32% of mothers in the PBCC and ECC arms, respectively. Two hundred ninety-five nonrandomised infants (55% female) with median (IQR) gestational age of 39.6 (38.6 to 40.6) weeks received DCC. Data from these infants was used to create percentile charts of expected HR and oxygen saturation in vigorous infants receiving DCC. The trial was limited by the small number of infants requiring prolonged or advanced resuscitation. PBCC may provide other important benefits we did not measure, including improved maternal–infant bonding and higher iron stores.ConclusionsIn this study, we observed that PBCC resulted in similar mean HR compared to infants receiving ECC. The findings suggest that for infants ≥32⁺⁰ weeks’ gestation who receive brief, effective resuscitation at closely monitored births, PBCC does not provide additional benefit over ECC (performed after initial drying and stimulation) in terms of key physiological markers of transition. PBCC was feasible using a simple, low-cost strategy at both cesarean and vaginal births. The percentile charts of HR and oxygen saturation may guide clinicians monitoring the transition of at-risk infants who receive DCC.Trial registrationAustralian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12618000621213.

Shiraz Badurdeen and colleagues evaluate whether physiologically-based cord clamping provides physiological benefits over early cord clamping for infants requiring resuscitation at birth.     

Enzyme-based formulations for decontamination: current state and perspectives

Development of noncorrosive, cost-effective, environmentally benign, and broad-spectrum antimicrobial formulations is necessary for clinical, industrial, and domestic purposes. Many current decontaminating formulations are effective, but they require the use of strong oxidizing agents or organic solvents that have deleterious effects on human health and the surrounding environment. The emergence of antibiotic-resistant pathogens has motivated researchers to develop enzyme-based self-decontaminating formulations as alternatives to such chemical decontamination approaches. Hydrolytic and oxidative enzymes can be used to deactivate pathogens, including bacteria, spores, viruses, and fungi. Laccases, haloperoxidases, and perhydrolases catalyze the generation of biocidal oxidants, such as iodine, bromine, hypohalous acid (e.g., HOCl or HOBr), and peracetic acid. These oxidants have broad-spectrum antimicrobial activity. Due to the multi-pathway action of these oxidants, it has proven extremely difficult for microbes to gain resistance. Thus far, few examples have been reported on enzyme-based antimicrobial formulations. For these reasons, various enzyme-containing antimicrobial formulations are highlighted in this review.     

Molecular Modeling of Calixarenes with Group I Metal Ions

Molecular mechanics calculations have been used to model the geometries of the complexes of Group I metal ions with calix[n]arenes (n = 4,5). A simple procedure in which the calixarene atoms are assigned partial charges on the basis of AM1 calculations and the metal ions are allowed to bind electrostatically to the calixarenes produces surprising good results when the resulting structures are compared to known crystallographic data on the complexes. Encapsulated solvent molecules and/or counterions can be included in the calculations and, indeed, are necessary to reproduce the X-ray data. Electronic Supplementary Material available.     

Tardive dyskinesia risk with first‐ and second‐generation antipsychotics in comparative randomized controlled trials: a meta‐analysis

Tardive dyskinesia (TD) risk with D2/serotonin receptor antagonists or D2 receptor partial agonists (second‐generation antipsychotics, SGAs) is considered significantly lower than with D2 antagonists (first‐generation antipsychotics, FGAs). As some reports questioned this notion, we meta‐analyzed randomized controlled studies (RCTs) to estimate the risk ratio (RR) and annualized rate ratio (RaR) of TD comparing SGAs vs. FGAs and SGAs vs. SGAs. Additionally, we calculated raw and annualized pooled TD rates for each antipsychotic. Data from 57 head‐to‐head RCTs, including 32 FGA and 86 SGA arms, were meta‐analyzed, yielding 32 FGA‐SGA pairs and 35 SGA‐SGA pairs. The annualized TD incidence across FGA arms was 6.5% (95% CI: 5.3‐7.8%) vs. 2.6% (95% CI: 2.0‐3.1%) across SGA arms. TD risk and annualized rates were lower with SGAs vs. FGAs (RR=0.47, 95% CI: 0.39‐0.57, p<0.0001, k=28; RaR=0.35, 95% CI: 0.28‐0.45, p<0.0001, number‐needed‐to‐treat, NNT=20). Meta‐regression showed no FGA dose effect on FGA‐SGA comparisons (Z=?1.03, p=0.30). FGA‐SGA TD RaRs differed by SGA comparator (Q=21.8, df=7, p=0.003), with a significant advantage of olanzapine and aripiprazole over other non‐clozapine SGAs in exploratory pairwise comparisons. SGA‐SGA comparisons confirmed the olanzapine advantage vs. non‐clozapine SGAs (RaR=0.66, 95% CI: 0.49‐0.88, p=0.006, k=17, NNT=100). This meta‐analysis confirms a clinically meaningfully lower TD risk with SGAs vs. FGAs, which is not driven by high dose FGA comparators, and documents significant differences with respect to this risk between individual SGAs.