Bioweathering of nontronite colloids in hybrid silica gel: implications for iron mobilization.

AIMS: This study aimed to study biotic iron dissolution using a new hybrid material constituted of well-dispersed mineral colloids in a silica gel matrix. This permitted to prevent adsorption of colloidal mineral particles on bacteria. Hybrid silica gel (HSG) permitted to study bioweathering mechanisms by diffusing molecules. METHODS AND RESULTS: Hybrid silica gel was synthesized through a classical sol-gel procedure in which mineral colloidal particles (NAu-2) were embedded in a porous silica matrix. Rahnella aquatilis RA1, isolated from a wheat rhizosphere was chosen for its ability to dissolve minerals by producing various organic acids and siderophores. Pyruvic, acetic and lactic acids were the major organic acids produced by R. aquatilis RA1 followed by oxalic and citric acids at the end of incubation. Comparison of abiotic and biotic experiments revealed a high efficiency of R. aquatilis RA1 for iron dissolution suggesting an optimized action of different ligands that solubilized or mobilized iron. CONCLUSIONS: Hybrid silica gel allowed focusing on the colloidal mineral weathering by metabolites diffusion without mineral adsorption on bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Hybrid silica gels are new and efficient tools to study colloidal mineral bioweathering. Adjusting HSG porosity and hydrophobicity should permit to precise the influence of limiting diffusion of siderophores or aliphatic organic acids on mineral weathering.

Frequencies of killer immunoglobulin-like receptor genotypes influence susceptibility to spontaneous abortion.

Natural killer (NK) cells are the most abundant lymphocyte population in the decidua. These cells express killer immunoglobulin-like receptors (KIRs), which upon recognition of HLA class I molecules on trophoblasts may either stimulate NK cells (activating KIRs) or inhibit them (inhibitory KIRs) to produce soluble factors necessary for the maintenance of pregnancy. KIR genes exhibit extensive haplotype polymorphism; individuals differ in both the number and kind (activating vs. inhibitory) of KIR genes. This polymorphism affects NK cell reactivity and susceptibility to diseases, including gynecological disorders. Therefore we KIR-genotyped 149 spontaneously aborting women and 117 control multiparae (at least 2 healthy-born children). Several genotypes (i.e. combinations of various KIR genes) were differently distributed among the patients and control subjects. Differences were observed in the numbers and the ratios of activating to inhibitory KIRs between patients and healthy women: (i) genotypes containing 6 activating KIR genes were less frequent and those containing 6 inhibitory KIR genes were more frequent in patients than in control subjects, and (ii) an excess of inhibitory KIRs (activating-to-inhibitory KIR gene ratios of 0.33 to 0.83) was associated with miscarriage, whereas ratios close to equilibrium (0.86-1.25) seemed to be protective. In addition, the results suggest for the first time that sporadic and recurrent spontaneous abortions as well as miscarriage in the presence or absence of autoantibodies may have different KIR genotypic backgrounds.

G, A and M immunoglobulin levels in parturient's blood serum, umbilical blood of their neonates and the amniotic fluid in physiological deliveries.

The present investigation is aimed at determination of G, A and M immunoglobulins concentration levels in the blood serum of parturients, umbilical blood of their neonates and in the amniotic fluid in 50 women with physiological pregnancy and delivery whose neonates were fully mature. In order to evaluate IgG, IgA and IgM concentration in the biological fluids, the method of inhibition of passive hemagglutination was applied. IgG and IgA were detected in all the three environments, while the presence of IgM was confirmed in all cases in the blood serum but only in 78% of the tested samples of the aminotic fluid. Mean values of IgG and IgM concentration both in the parturients' serum as well as in the umbilical blood of their neonates as compared with the values found in the amniotic fluid, revealed statistically significant differences. The statistically significant correlation noted between the values of IgG concentration in the parturients' serum and the umbilical blood of their neonates was not confirmed in the case of IgA and IgM.

G, A and M immunoglobulin levels in the parturients' blood serum, umbilical blood of their neonates, and the amniotic fluid in deliveries of prolonged pregnancies.

The present experiments were carried out with the aim to determine G, A and M immunoglobulin concentration levels in the blood serum of parturients, umbilical blood of their neonates, and in the amniotic fluid in 17 women with prolonged pregnancies. The diagnosis of prolonged pregnancy was confirmed by the typical after term traits in infants. IgG and IgA were detected in all three environments and the presence of IgM was confirmed in all cases in the blood serum and in 76% of the tested samples of amniotic fluid. IgG concentration in the blood serum of mothers with prolonged pregnancy was lower than in physiological pregnancies. Despite this IgG level in the serum of umbilical blood of the neonates was normal in all cases. The values of IgA and IgM were noted to be normal both in the parturients' blood serum as well as in the umbilical blood. Examination of the amniotic fluid did not reveal significant differences in immunoglobulin levels related to the duration of full term pregnancy compared to prolonged pregnancy.

Vascular endothelial growth factor (VEGF) concentration in sera and tumor effusions from patients with ovarian carcinoma.

VEGF is an important angiogenic cytokine with a critical role in tumor angiogenesis. VEGF concentrations were measured using an ELISA assay, detecting VEGF165 isoform, in tumor cyst and/or ascitic fluids and in sera of 86 patients with malignant neoplasms and in 53 patients with benign ovarian neoplasms. VEGF levels were significantly elevated in the sera and cyst fluids of carcinoma patients compared with patients who had benign neoplasms. In carcinoma patients, statistically higher VEGF levels were detected in tumor effusions than in corresponding sera. The differences between VEGF values in sera and tumor effusions in relation to histological subtypes of ovarian carcinoma and FIGO stages were statistically insignificant. High VEGF levels in ascitic fluids appeared to be significantly associated with shorter disease-free survival and overall survival In multivariate analysis, besides FIGO stage and age of patients, only serum VEGF concentration was an independent prognostic factor for overall survival. The elevated VEGF levels in sera and tumor effusions of patients with FIGO stages I/II indicated that angiogenesis promoted by VEGF is a continuous process, independent of clinical advancement of the disease.

IL-6 production in ovarian carcinoma is associated with histiotype and biological characteristics of the tumour and influences local immunity.

The presence of interleukin (IL)-6 in peritoneal carcinomatous fluid (PCF) and its effect on immune cells composition in PCF in patients with advanced ovarian carcinoma was studied. In 21 out of 30 ovarian carcinoma patients, PCF IL-6 levels were found to exceed those seen in PCFs of patients with gastrointestinal cancer. IL-6 activity was higher in serous/mucinous than in endometrioid and undifferentiated ovarian carcinoma PCF (P = 0.05). Ovarian carcinoma PCF IL-6 activities were correlated with serum C-reactive protein levels (r = 0.65, P = 0.0000, n = 25). Ovarian carcinoma PCF leucocyte profile differed from that in blood with respect to: (i) lower percentage of NK and CD8+ and (ii) higher percentage of B and CD45RO+, CD14+ and HLA-DR+ cells. The proportions of CD45RO+ in blood were correlated with IL-6 levels in PCF. Corresponding to PCF ovarian carcinoma tumours were stained for the presence of Ki-67 antigen and p53. The highest proportions of Ki-67+ cells and cells showing accumulation of p53 were seen in undifferentiated tumours. A low grade of p53 staining was seen in tumours associated with high IL-6 levels in PCF. It was evident that IL-6 production (i) depended on the histiotype of the tumour, (ii) influenced the local immune system in favour of accumulation of B, and T memory cells, and (iii) was higher in patients lacking p53 accumulation.