Los dobletes etimológicos en español (1611-1739)

OBJECTIVES: Bacterial translocation seems to precede the occurrence of overt bacterial infection in patients with cirrhosis. The presence of bacterial DNA in blood and ascites correlates with bacterial translocation and is frequent in patients with advanced cirrhosis without overt infection. Our aim was to search for bacterial DNA in patients with cirrhosis both with and without ascites, and to study its correlation with abnormal intestinal motility or permeability and the presence of bacterial overgrowth. METHODS: Blood and ascites samples were obtained on day 1, and blood samples were taken twice a day for the following 3 days. Bacterial DNA was assayed by polymerase chain reaction using universal primers for rRNA 16\u2009s. Oro-caecal transit time and bacterial overgrowth were assessed with Lactulose H(2) breath testing. Intestinal permeability was assessed by determining urinary lactulose and mannitol excretion with high performance liquid chromatography. RESULTS: We studied seven patients (six were male, age range was 42-78 years). Aetiology was alcohol in four, HCV in two, HBV in one; ascites was present in four and Child-Pugh grade was A in four and B in three. All patients had increased intestinal permeability, six had decreased transit time and one had bacterial overgrowth. In only one patient (with ascites), polymerase chain reaction was positive for bacterial DNA both in ascites and serum for all 4 days on which samples were taken. CONCLUSION: Increased intestinal permeability and abnormal motility were frequent without evidence of bacterial translocation in cirrhosis even without ascites. They are likely to be facilitators for bacterial translocation and thus precede it

Fate of Pathogenic Bacteria in Microcosms Mimicking Human Body Sites.

During the infectious process, pathogens may reach anatomical sites where they are exposed to substances interfering with their growth. These substances can include molecules produced by the host, and his resident microbial population, as well as exogenous antibacterial drugs. Suboptimal concentrations of inhibitory molecules and stress conditions found in vivo (high or low temperatures, lack of oxygen, extreme pH) might induce in bacteria the activation of survival mechanisms blocking their division capability but allowing them to stay alive. These "dormant" bacteria can be reactivated in particular circumstances and would be able to express their virulence traits. In this study, it was evaluated the effect of some environmental conditions, such as optimal and suboptimal temperatures, direct light and antibiotic sub-inhibitory concentrations doses of antibiotic, on the human pathogens Escherichia coli and Enterococcus faecalis when incubated in fluids accumulated in the body of patients with different pathologies. It is shown that inoculation in a number of accumulated body fluids and the presence of gentamicin, reliable conditions encountered during pathological states, induce stress-responding strategies enabling bacteria to persist in microcosms mimicking the human body. Significant differences were detected in Gram-negative and Gram-positive species with E. faecalis surviving, as starved or viable but non-culturable forms, in any microcosm and condition tested and E. coli activating a viable but non-culturable state only in some clinical samples. The persistence of bacteria under these conditions, being non-culturable, might explain some recurrent infections without isolation of the causative agent after application of the standard microbiological methods

Adhesion to medical materials and biofilm formation capability of some species of enterococci in different physiological states.

Enterococci may survive in adverse environments including the human body where bacteriocins, antibiotics, iron-limitation and immune response represent stressing conditions for bacteria that cause division block. In those conditions, bacteria present in the human body would hardly be in an exponentially growing phase but would mostly be in physiological states such as starvation or the viable but nonculturable (VBNC) state. The possibility that the starved and VBNC bacteria can maintain their ability to adhere to living and inanimate substrates is the first mandatory step for them potentially to cause an infection process. In this study it is shown that starved and stationary enterococcal cells are able to form biofilms on plastic material albeit with reduced efficiency as compared to growing cells. Moreover, although VBNC enterococcal forms are not capable of forming biofilms, Enterococcus faecalis and other enterococcal species of medical interest maintain their ability to synthesize the polymeric matrix for a limited period of time under adverse environmental conditions. The data presented, together with those regarding the maintenance of the division recovery potential already proved in nonculturable bacteria, further support the possibility for the VBNC and other nondividing bacterial forms to have a role as infectious agents and to constitute a risk to human health

STRUCTURE AND CONFORMATION OF STEREOISOMERIC C-ISOPROPOXYCARBONYLMETHYLCALIX[4]RESORCINARENES

Treatment of (E)-2,4-dimethoxycinnamic acid isopropyl esters with boron trifluoride-diethyl ether in chloroform at room temperature affords various stereoisomeric C-alkylcalix[4]resorcinarenes, which differ in their conformations; the crystal structures of two stereoisomers have been determined and compared with geometries resulting from theoretical calculations

Bis(diamido)-bridged basket resorcin[4]arenes as enantioselective receptors for amino acids and amines

On the research avenue opened by the rigidified double-spanned resorcin[4]arene 1, we have synthesized both enantiomers of the two chiral basket resorcin[4]arenes 3 and 4, each containing two 1,2-diaminocyclohexane and 1,2-diphenylethylenediamine bridges, respectively. In the new compounds, the aromatic rims assume the expected flattened cone arrangement, whereas two different conformations, tentatively designated as "open wings" and "folded wings", were attributed to the bridge substituents according to molecular modeling studies. In MSn (ESI) experiments, the proton-bonded diastereomeric [4.H.A](+) complexes with amino acidic guests (A) exhibited a pronounced selectivity towards the enantiomers of tyrosine methyl ester (tyr(OMe)) and amphetamine (amph), whereas the chirality of tryptophan (trp) was ineffective. Moreover, a kinetic study on the base-induced displacement of the guest revealed that the L-tyr(OMe) (and L-amph) enantiomer is faster displaced from the heterochiral [4.H.L-tyr(OMe)](+) (or [ent-4.H.L-amph](+)) complex than from the homochiral [ent-4.H.L-tyr(OMe)](+) (or [4.H.L-amph](+)) one