Full scale study of Class A biosolids produced by thermal hydrolysis pretreatment and anaerobic digestion.

Biosolids are the solid by-product of wastewater treatment and contain high-organic matter and nutrient content, which can be utilized in food production and gardening. In 2014, this study's target nutrient recovery facility (NRF) in the Mid-Atlantic region of the U.S. adopted thermal hydrolysis pretreatment (THP) and anaerobic digestion (AD) to upgrade biosolids from Class B (lime-stabilized) to Class A. The pathogen, nutrients, and metals contents were compared with that of Class B biosolids from the same facility throughout a one-year period. Following optimization and equilibrium, stable biosolids were produced that satisfied all Environmental Protection Agency (EPA) Class A biosolids standards. Class A biosolids produced had fecal coliform density consistently below the 1000 MPN/g d.w. limit set by the EPA, at 35.85 ±â€¯81.10 MPN/g d.w. (n = 301). Metal concentrations were greater in Class A than Class B biosolids as a result of biosolids mass reduction, but these levels were substantially lower than regulatory limits. Metal concentrations were (in mg/kg d.w.): As = 6.43 ±â€¯0.400 (n = 141), Cd = 3.39 ±â€¯0.117 (n = 147), Cr = 88.4 ±â€¯2.00 (n = 148), Cu = 401 ±â€¯9.81 (n = 148), Pb = 68.1 ±â€¯2.19 (n = 148), Hg = 1.21 ±â€¯0.116 (n = 148), Mo = 14.9 ±â€¯0.321 (n = 148), Ni = 23.8 ±â€¯0.911 (n = 146), Se = 10.0 ±â€¯0.573 (n = 140), Zn = 778 ±â€¯14.9 (n = 148), K = 850 ±â€¯21.7 (n = 134). In addition, Class A biosolids were rich in total nitrogen (N) and higher in total phosphorus (TP), but low in potassium (K) content. Concentration of K was 850 ±â€¯21.7 mg/kg d.w. (n = 134), TKN was 52,000 ±â€¯13,300 mg/kg d.w. (n = 43), TP was 34,500 ±â€¯6130 mg/kg d.w. (n = 42), and ammonia-N was 7860 ±â€¯1350 mg/kg d.w. (n = 43).

The plasma pharmacokinetics of R-(+)-lipoic acid administered as sodium R-(+)-lipoate to healthy human subjects.

BACKGROUND: The racemic mixture, RS-(+/-)-alpha-lipoic acid (rac-LA) has been utilized clinically and in a variety of disease models. Rac-LA and the natural form, R-lipoic acid (RLA), are widely available as nutritional supplements, marketed as antioxidants. Rac-LA sodium salt (NaLA) or rac-LA potassium salt (KLA) has been used to improve the aqueous solubility of LA. STUDY RATIONALE: Several in vitro and animal models of aging and age-related diseases have demonstrated efficacy for the oral solutions of LA salts in normalizing age-related changes to those of young animals. Other models and studies have demonstrated the superiority of RLA, the naturally occurring isomer over rac-LA. Despite this, RLA pharmacokinetics (PK) is not fully characterized in humans, and it is unknown whether the concentrations utilized in animal models can be achieved in vivo. Due to its tendency to polymerize, RLA is relatively unstable and suffers poor aqueous solubility, leading to poor absorption and low bioavailability. A preliminary study demonstrated the stability and bioavailability were improved by converting RLA to its sodium salt (NaRLA) and pre-dissolving it in water. The current study extends earlier findings from this laboratory and presents PK data for the 600-mg oral dosing of 12 healthy adult subjects given NaRLA. In addition, the effect of three consecutive doses was tested on a single subject relative to a one-time dosing in the same subject to determine whether plasma maximum concentration (Cmax) and the area under the plasma concentration versus time curve (AUC) values were comparable to those in animal studies and those achievable via intravenous infusions in humans. METHODS: Plasma RLA was separated from protein by a modification of a published method. Standard curves were generated from spiking known concentrations of RLA dissolved in ethanol and diluted in a phosphate-buffered saline (PBS) into each individual's baseline plasma to account for inter-individual differences in protein binding and to prevent denaturing of plasma proteins. Plasma RLA content was determined by the percent recovery using high-performance liquid chromatography (electrochemical/coulometric detection) (HPLC/ECD). RESULTS: As anticipated from the preliminary study, NaRLA is less prone to polymerization, completely soluble in water, and displays significantly higher Cmax and AUC values and decreased time to maximum concentration (Tmax) and T1/2 values than RLA or rac-LA. In order to significantly extend Cmax and AUC, it is possible to administer three 600-mg RLA doses (as NaRLA) at 15-minute intervals to achieve plasma concentrations similar to those from a slow (20-minute) infusion of LA. This is the first study to report negligible unbound RLA even at the highest achievable plasma concentrations.

The crystal structure of the rhomboid peptidase from Haemophilus influenzae provides insight into intramembrane proteolysis.

Rhomboid peptidases are members of a family of regulated intramembrane peptidases that cleave the transmembrane segments of integral membrane proteins. Rhomboid peptidases have been shown to play a major role in developmental processes in Drosophila and in mitochondrial maintenance in yeast. Most recently, the function of rhomboid peptidases has been directly linked to apoptosis. We have solved the structure of the rhomboid peptidase from Haemophilus influenzae (hiGlpG) to 2.2-A resolution. The phasing for the crystals of hiGlpG was provided mainly by molecular replacement, by using the coordinates of the Escherichia coli rhomboid (ecGlpG). The structural results on these rhomboid peptidases have allowed us to speculate on the catalytic mechanism of substrate cleavage in a membranous environment. We have identified the relative disposition of the nucleophilic serine to the general base/acid function of the conserved histidine. Modeling a tetrapeptide substrate in the context of the rhomboid structure reveals an oxyanion hole comprising the side chain of a second conserved histidine and the main-chain NH of the nucleophilic serine residue. In both hiGlpG and ecGlpG structures, a water molecule occupies this oxyanion hole.