Specific Ion Effects on the Interaction of Hydrophobic and Hydrophilic Self-Assembled Monolayers.

Interactions between mineral surfaces and organic molecules are fundamental to life processes. The presence of cations in natural environments can change the behavior of organic compounds and thus alter the mineral-organic interfaces. We investigated the influence of Na+, Mg2+, Ca2+, Sr2+, and Ba2+ on the interaction between two models, self-assembled monolayers, that were tailored to have hydrophobic -CH3 or hydrophilic -COO(H) terminations. Atomic force microscopy in chemical force mapping mode, where the tips were functionalized with the same terminations, was used to measure adhesion forces between the tip and substrate surfaces, to gather fundamental information about the role of these cations in the behavior of organic compounds and the surfaces where they adsorb. Adhesion force between hydrophobic surfaces in 0.5 M NaCl solutions that contained 0.012 M divalent cations did not change, regardless of the ionic potential, that is, the charge per unit radius, of the cation. For systems where one or the other surface was functionalized with carboxylate, -COO(H), mostly in its deprotonated form, -COO-, a reproducible change in the adhesion force was observed for each of the ions. The trend of increasing adhesion force followed the pattern: Na+ ≈ Mg2+ < Sr2+ < Ca2+ < Ba2+, suggesting that ionic potential, thus hydrated radius, controls the interaction. The presence of a -CH3 surface in the asymmetric system leads to lower adhesion forces than in the hydrophilic system, whereas the ionic trend remains the same. Although specific ion effects are felt in both systems, the lower adhesion force in the asymmetric system, compared with the hydrophilic system, implies that the -CH3 surface plays an important role.

The degradation of arabinoxylan-rich cell walls in digesta obtained from piglets fed wheat-based diets varies depending on digesta collection site, type of cereal, and source of exogenous xylanase.

The objective of the present study was to compare the ability of experimental and commercial xylanases to degrade, in vitro, the arabinoxylan (AX) fraction in digesta from 28-d-old piglets fed a wheat (Triticum aestivum)-based diet (49% wheat). Pigs were euthanized at 1, 2, 3, or 4 h after feeding; stomach and ileum contents were isolated and frozen and later used for the in vitro studies. Xylan solubilization provided information regarding the ability of the enzymes to degrade AX during the harsh in vivo conditions prevailing in the gastrointestinal tract. The hydrolytic capacity of a commercial xylanase was compared with that of an experimental xylanase using stomach digesta (pH 1.8) obtained at 4 h after feeding. Relative to the control, both enzymes increased (P < 0.001) xylan solubilization 3-fold. In the ileal digesta (1 h), xylan solubilization was increased by 36% (P < 0.001). Inclusion of arabinofuranosidases (Ara f) with xylanases increased xylan solubilization in stomach samples (P = 0. 007 and P = 0. 030) but not in ileal samples (P = 0.873 and P = 0.997). Our results illustrate clearly the importance of using different conditions and substrates when enzyme performance is studied in vitro as a prescreening tool for setting up in vivo trials.

Two proximal activating protein-1-binding sites are sufficient to stimulate transcription of the ovine follicle-stimulating hormone-beta gene.

FSH is an important regulator of mammalian gametogenesis and the female reproductive cycle. Although little is known about the transcriptional regulation of the beta-subunit (the rate-limiting subunit of FSH synthesis), sequence analysis of the ovine FSHbeta promoter has revealed a number of potential activating protein-1 (AP-1; Jun/Fos)-binding sites. To determine whether the gene encoding the beta-subunit of ovine FSH (oFSHbeta) is responsive to AP-1 transcriptional complexes, chimeric constructs containing deleted portions of the oFSHbeta promoter fused to a luciferase reporter were transiently transfected along with c-Jun and c-Fos expression constructs into JAR cells. Analysis of these deletion constructs revealed that the proximal promoter of oFSHbeta is highly stimulated by c-Jun and c-Fos proteins (typically 20-fold with a reporter construct containing oFSHbeta sequences from -215 to +759 bp). This stimulation was lost when a similar construct containing sequences from -84 to +759 bp was tested. Transcriptional start site analysis using reverse transcription-PCR verified that the transcriptional initiation of the -215-bp deletion construct, with or without cotransfected c-Jun/c-Fos, was the same as that observed in vivo. Computer analysis of oFSHbeta sequences from -215 to +1 bp identified four putative AP-1-like elements, located at -155, -120, -83, and -10 bp. Gel retardation experiments using oligonucleotides corresponding to the four putative AP-1-like sites revealed that only -120 and -83 sites in oFSHbeta bound AP-1 proteins in vitro. Site-directed mutagenesis of the -120 and -83 sites showed that each element was required for stimulation by c-Jun and c-Fos proteins as well as 12-O-tetradecanoyl phorbol-13-acetate in transient transfection assays. Finally, immunocytochemical dual labeling was used to show that more than 75% of all FSHbeta-containing cells in ovine pituitary sections from cycling ewes contained nuclear c-Jun, JunB, JunD, and Fos proteins. These data, taken together, show that oFSHbeta transcription can be stimulated by c-Jun and c-Fos proteins via two functionally linked AP-1-like sites in the oFSHbeta proximal promoter and that these sites are likely to be important regulators of FSH production in vivo.

[Fulminant myonecrosis and sepsis caused by Aeromonas hydrophila]. / Fulminant myonekrose og sepsis forårsaget af Aeromonas hydrophila.

A case of fatal bilateral lower extremity myonecrosis in a nonimmunocompromized man with septicaemia caused by Aeromonas hydrophila is described. Immediate surgical revision combined with treatment with new cephalosporins should be considered in the treatment of severe soft tissue infections, especially when the patient is known to have a trauma with waterborne contamination or is immunocompromised.

The 5'-flanking region of the ovine follicle-stimulating hormone-beta gene contains six progesterone response elements: three proximal elements are sufficient to increase transcription in the presence of progesterone.

Progesterone (P4) can alter the synthesis and secretion of FSH from pituitary gonadotropes of sheep. In this study, the 5'-flanking region (4.7 kilobases) of the ovine FSH beta gene was tested for binding by human progesterone receptors (hPR), using an immunoprecipitation technique. Three fragments were bound by hPR. Competition experiments using homologous and heterologous DNA fragments revealed this binding to be specific and of high affinity (Kd = 1.2-47 nM). The fragment sequences were screened for potential P4 response elements (PREs). Six PRE-like elements were found among the three immunoprecipitated fragments. Band shift experiments discerned that each of these PRE-like sequences could be bound by hPR. In functional studies, each of the PRE-like elements could enhance the expression of a reporter gene driven by a heterologous promoter in a hormone-dependent manner. The 5'-flanking region of the ovine FSH beta gene was tested for P4 responsiveness using a luciferase reporter. In the presence of P4, there was a 2- to 3-fold increase in luciferase activity when the entire 4.7 kilobases of the 5'-flanking sequence were present, whereas no increase was seen in a construct that contained only 84 basepairs 5' to the transcription start site. This effect on transcription was dose dependent for P4. Deletion studies revealed that the three PRE-like elements closest to the transcription start site (-250 to -137) were sufficient to create the hormone-dependent enhancement. These results indicate that the 5'-flanking sequence of the ovine FSH beta gene contains sequences capable of being bound by hPR and may be responsible for the effects of P4 on FSH beta synthesis and secretion. This study is the first to show binding and function of PR for a gonadotropin gene.