An investigation of the assay of dopamine using trinitrobenzensulphonic acid.

The reaction between 2,4,6-trinitrobenzene-1-sulphonic acid with 3,4-dihydroxy-phenylethylamine (dopamine) to form trinitrophenyl dopamine (TNP-dopamine) is found to be complex in that the TNP-dopamine is unstable. The course of the reaction shows TNP-dopamine rising to a steady state concentration equal to about half the initial dopamine concentration within 20 min and then decomposing with a half-time of about 1 hr. Continuous extraction into benzene to separate the TNP-dopamine from TNP-DOPA, which interferes with the spectrophotometric assay, also prevents the decomposition of TNP-dopamine so that quantitative recoveries are obtained. The method has been used to follow the course of a DOPA decarboxylase-catalysed reaction satisfactorily.     

Antibacterial activity associated with Lactobacillus gasseri ATCC 9857from the human female genitourinary tract

The 10-fold concentrated spent MRS culture cell-free supernatant concentrate [(cCFS)] of the human female genitourinary tract isolate Lactobacillus gasseri ATCC 9857 was shown to exhibit antibacterial activity towards gram-positive sporogenous and asporogenous fermentative eubacteria in liquid and on solid media under conditions that eliminated the activity of lactic acid (-glycerophosphate) and hydrogen peroxide (catalase). The antibacterial activity of the cCFS was characterized by automated turbidometry (Bioscreen) and non-linear regression analysis (Gompertz model) using MRS broth cultures of the indicator strain L. acidophilus ATCC 11975. It exhibited a bactericidal mode of action, sensitivity to trypsin and proteinase K, partial sensitivity to pepsin and pronase E, partial heat stability at 121 °C for 15 min, and retained significantly more activity following exposure to pH 3.0 and 5.0 compared with pH 7.2 and 9.0. The inhibitory spectrum included a wide range of Lactobacillus species, Bifidobacterium bifidum, B. infantis and B. catenulatum, Lactococcus cremoris, Leuconostoc cremoris, Pediococcus pentosaceus, Bacillus cereus, Clostridium tyrobutyricum, C. pasteurianum, C. sporogenes, Staphylococcus carnosus, and Enterococcus faecalis. Although partial inhibition of Escherichia coli ATCC 25922 by cCFS was observed in liquid medium, inhibition of freshly isolated human uropathogenic E. coli strains could not be demonstrated on TSB agar plates by agar well diffusion. Following partial resolution by gel permeation FPLC on Superose-12, the fractionated cCFS was shown to comprise at least two inhibitory peptides (3.05 and 5.27 kDa) as well as aggregated inhibitory peptide material (21.65, 41.50, 81.20, and 120.90 kDa). The 3.05 kDa peptide, designated Gassericin D, inhibited L. acidophilus strains ATCC 11975 and ACA-DC 241. The 5.27 kDa peptide, designated Gassericin C, inhibited L. gasseri strain UCSC LF221Snb and En. faecalis DPC 3319. The aggregated 21.65 kDa peptide material strongly inhibited L. acidophilus ATCC 11975 and weakly inhibited Listeria inocua DPC 3306. The aggregated 41.50 kDa peptide material strongly inhibited Ba. cereus DPC 3316 and weakly inhibited L. acidophilus ACA-DC 241. The ability of L. gasseri ATCC 9857 to produce bacteriocin-like activity may be of importance in the biopreservation of nutraceuticals and in the management of female genitourinary and gastrointestinal tract infections involving En. faecalis.     

Reactions of DOPA (3,4-dihydroxyphenylalanine) decarboxylase with DOPA.

The study of DOPA (3,4-dihydroxyphenylalanine) decarboxylase by steady-state methods is difficult because multiple reactions occur. The reaction with DOPA was studied at enzyme concentrations between 20 and 50 micrometer by direct observation of the bound coenzyme by using stopped-flow and conventional spectrophotometry. Four processes were observed on different time scales and three of these were attributed to stages in the decarboxylation. The fourth was attributed to an accompanying transamination that renders the enzyme inactive. It was clear that much, if not all, of the 330 nm-absorbing coenzyme present in the free enzyme plays an active part in the decarboxylation, since it is converted into 420 nm-absorbing material in the first observable step. An intermediate absorbing maximally at 390 nm is formed in a slower step. Rate and equilibrium constants have been determined and the ratio of decarboxylation to transamination was estimated to be 1200:1.     

Meta‐analysis of global livestock urine‐derived nitrous oxide emissions from agricultural soils

Nitrous oxide (N₂O) is an air pollutant of major environmental concern, with agriculture representing 60% of anthropogenic global N₂O emissions. Much of the N₂O emissions from livestock production systems result from transformation of N deposited to soil within animal excreta. There exists a substantial body of literature on urine patch N₂O dynamics, we aimed to identify key controlling factors influencing N₂O emissions and to aid understanding of knowledge gaps to improve GHG reporting and prioritize future research. We conducted an extensive literature review and random effect meta‐analysis (using REML) of results to identify key relationships between multiple potential independent factors and global N₂O emissions factors (EFs) from urine patches. Mean air temperature, soil pH and ruminant animal species (sheep or cow) were significant factors influencing the EFs reviewed. However, several factors that are known to influence N₂O emissions, such as animal diet and urine composition, could not be considered due to the lack of reported data. The review highlighted a widespread tendency for inadequate metadata and uncertainty reporting in the published studies, as well as the limited geographical extent of investigations, which are more often conducted in temperate regions thus far. Therefore, here we give recommendations for factors that are likely to affect the EFs and should be included in all future studies, these include the following: soil pH and texture; experimental set‐up; direct measurement of soil moisture and temperature during the study period; amount and composition of urine applied; animal type and diet; N₂O emissions with a measure of uncertainty; data from a control with zero‐N application and meteorological data.     

The T309G MDM2 Gene Polymorphism Is a Novel Risk Factor for Proliferative Vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is still the major cause of failure in retinal detachment (RD) surgery. It is believed that down-regulation in the p53 pathway could be an important key in PVR pathogenesis. The purpose was to evaluate the impact of T309G MDM2 polymorphism (rs2279744) in PVR. Distribution of T309G MDM2 genotypes among European subjects undergoing RD surgery was evaluated. Proportions of genotypes between subsamples from different countries were analyzed. Also, a genetic interaction between rs2279744 in MDM2 and rs1042522 in p53 gene was analyzed. Significant differences were observed comparing MDM2 genotype frequencies at position 309 of intron 1 between cases (GG: 21.6%, TG: 54.5%, TT: 23.8%) and controls (GG: 7.3%, TG: 43.9%, TT: 48.7%). The proportions of genotypes between sub-samples from different countries showed a significant difference. Distribution of GG genotype revealed differences in Spain (35.1–53.0)/(22.6–32.9), Portugal (39.0–74.4)/(21.4–38.9), Netherlands (40.6–66.3)/(25.3–38.8) and UK (37.5–62.4)/(23.3–34.2). The OR of G carriers in the global sample was 5.9 (95% CI: 3.2 to 11.2). The OR of G carriers from Spain and Portugal was 5.4 (95% CI: 2.2–12.7), whereas in the UK and the Netherlands was 7.3 (95% CI: 2.8–19.1). Results indicate that the G allele of rs2279744 is associated with a higher risk of developing PVR in patients undergoing a RD surgery. Further studies are necessary to understand the role of this SNP in the development of PVR.