Vegetal diamine oxidase alleviates histamine-induced contraction of colonic muscles

Excess of histamine in gut lumen generates a pronounced gastrointestinal discomfort, which may include diarrhea and peristalsis dysfunctions. Deleterious effects of histamine can be alleviated with antihistamine drugs targeting histamine receptors. However, many antihistamine agents come with various undesirable side effects. Vegetal diamine oxidase (vDAO) might be a relevant alternative owing to its histaminase activity. Mammalian intestinal mucosa contains an endogenous DAO, yet possessing lower activity compared to that of vDAO preparation. Moreover, in several pathological conditions such as inflammatory bowel disease and irritable bowel syndrome, this endogenous DAO enzyme can be lost or inactivated. Here, we tested the therapeutic potential of vDAO by focusing on the well-known effect of histamine on gut motility. Using ex vivo and in vitro assays, we found that vDAO is more potent than commercial anti-histamine drugs at inhibiting histamine-induced contraction of murine distal colon muscles. We also identified pyridoxal 5′-phosphate (the biologically active form of vitamin B6) as an effective enhancer of vDAO antispasmodic activity. Furthermore, we discovered that rectally administered vDAO can be retained on gut mucosa and remain active. These observations make administration of vDAO in the gut lumen a valid alternative treatment for histamine-induced intestinal dysfunctions

MedNet status report

MedNet is a network of very broadband seismic stations installed in countries bordering the Mediterranean area. The project started in 1987, with a final goal of 12-15 stations and a spacing of about 1000 km between stations. It was motivated both by research interest and by seismic hazard monitoring. The network presently comprises 23 operating stations, all of them equipped with state of the art seismographic stations. Presently, fully automatic network functions include: - daily monitoring of state of health; - data recover after link failures; - triggered retrieval of event waveforms; - update of web pages (http://mednet.ingv.it) for events and station information.PublishedS. Fernando (SPAIN)1.1. TTC - Monitoraggio sismico del territorio nazionaleope

Structural variations of vaginal and endometrial microbiota. Hints on female infertility

Microbiota are microorganismal communities colonizing human tissues exposed to the external environment, including the urogenital tract. The bacterial composition of the vaginal microbiota has been established and is partially related to obstetric outcome, while the uterine microbiota, considered to be a sterile environment for years, is now the focus of more extensive studies and debates. The characterization of the microbiota contained in the reproductive tract (RT) of asymptomatic and infertile women, could define a specific RT microbiota associated with implantation failure. In this pilot study, 34 women undergoing personalized hormonal stimulation were recruited and the biological samples of each patient, vaginal fluid, and endometrial biopsy, were collected immediately prior to oocyte-pick up, and sequenced. Women were subsequently divided into groups according to fertilization outcome. Analysis of the 16s rRNA V4-V5 region revealed a significant difference between vaginal and endometrial microbiota. The vaginal microbiota of pregnant women corroborated previous data, exhibiting a lactobacilli-dominant habitat compared to non-pregnant cases, while the endometrial bacterial colonization was characterized by a polymicrobial ecosystem in which lactobacilli were exclusively detected in the group that displayed unsuccessful in vitro fertilization. Overall, these preliminary results revisit our knowledge of the genitourinary microbiota, and highlight a putative relationship between vaginal/endometrial microbiota and reproductive success

Plasma membrane as a site of redox activation of daunomycin in intact human erythrocytes: quantitative evaluation of the hydrogen peroxide produced by the membrane with respect to the cytosol.

The relative importance in human red blood cells of the plasma membrane as a site of redox activation of anthracyclines as compared to hemoglobin was evaluated by assaying the H2O2 produced upon exposure to daunomycin. The method of H2O2-dependent irreversible inhibition of catalase (EC 1.11.1.6) activity by 3-amino-1,2,4-triazole was applied to intact erythrocytes, as well as to isolated membranes with added purified catalase. The results obtained indicate a secondary role in daunomycin activation for the plasma membrane from a quantitative point of view, although membrane pathways can be more harmful than cytosolic pathways, especially towards extracellular targets, when the high efficiency of the cytosolic antioxidative defences and the external location of the membrane activation site are considered

Plasma membrane as a site of redox activation of daunomycinin in intact human erythrocytes. Quantitative evaluation of the hydrogen peroxide produced by the membrane with respect to the cytosol

The relative importance in human red blood cells of the plasma membrane as a site of redox activation of anthracyclines as compared to hemoglobin was evaluated by assaying the H2O2 produced upon exposure to daunomycin. The method of H2O2-dependent irreversible inhibition of catalase (EC 1.11.1.6) activity by 3-amino-1,2,4-triazole was applied to intact erythrocytes, as well as to isolated membranes with added purified catalase. The results obtained indicate a secondary role in daunomycin activation for the plasma membrane from a quantitative point of view, although membrane pathways can be more harmful than cytosolic pathways, especially towards extracellular targets, when the high efficiency of the cytosolic antioxidative defences and the external location of the membrane activation site are considered

Catalytic mechanism of copper amine oxidase.

Società Italiana di Biochimica e Biologia Molecolare, Biogenic Amines, Albere' di Tenna (Trento

Is the catalytic mechanism of bacteria, plant, and mammal copper-TPQ amine oxidases identical?

University of Southampton, U

Is the catalytic mechanism of bacteria, plant, and mammal copper-TPQ amine oxidases identical?

This short review is mostly concerned with the work carried out in Rome on the copper amine oxidase from bovine serum (BSAO). The first target was the copper oxidation state and its relationship with the organic cofactor. It was found that copper is not reduced on reaction with amines under anaerobic conditions or along the catalytic cycle and that it is not within bonding distance of the quinone cofactor. The copper stability in the oxidised state was supported by BSAO ability to oxidise benzylhydrazine, a slow substrate, in the presence of N,N-diethyldithiocarbamate (DDC) and by the substantial catalytic activity of Co(2+)-substituted BSAO. Parallel work established that only one subunit of the dimeric enzyme readily binds reagents of the carbonyl group. Flexible hydrazides with a long aromatic tail were found to be highly specific inhibitors, suggesting the presence of an extended hydrophobic region at the catalytic site. A study by stopped-flow transient spectroscopy and steady state kinetics led to the formulation of a simplified, yet complete and consistent, catalytic mechanism for BSAO that was compared with that available for lentil seedling amine oxidase (LSAO). As in other copper amine oxidases, BSAO is inactivated by H(2)O(2) produced in the catalytic reaction, while the cofactor is stabilised in its reduced state. A conserved tyrosine hydrogen-bonded to the cofactor might be oxidised

Substrate specificity of copper-containing plant amine oxidases

The steady-state kinetic parameters of the amine oxidases purified from Lathyrus cicera (LCAO) and Pisum sativum (PSAO) seedling were measured on a series of common substrates, previously tested on bovine serum amine oxidase (BSAO). LCAO, as PSAO, was substantially more reactive than BSAO with aliphatic diamines and histamine. The k(cat) and k(cat)/K-m for putrescine were four and six order of magnitude higher, respectively. Differences were smaller with some aromatic monoamines. The plot of k(cat) versus hydrogen ions concentration produced bell-shaped curves, the maximum of which was substrate dependent, shifting from neutral pH with putrescine to alkaline pH with phenylethylamine and benzylamine. The latter substrates made the site more hydrophobic and increased the pK(a) of both enzyme-substrate and enzyme-product adducts. The plot of k(cat)/K-m versus hydrogen ion concentration produced approximately parallel bell-shaped curves. Similar pK(a) couples were obtained from the latter curves, in agreement with the assignment as free enzyme and free substrate pK(a). The limited pH dependence of kinetic parameters suggests a predominance of hydrophobic interactions. (c) 2007 Elsevier Inc. All rights reserved