Legionella pneumophila in Cooling Towers: Fluctuations in Counts, Determination of Genetic Variability by Pulsed-Field Gel Electrophoresis (PFGE), and Persistence of PFGE Patterns

The concentrations of Legionella pneumophila in cooling towers may vary considerably over short periods of time, producing significant fluctuations throughout the year. Despite genetic variability, in small geographical areas the same indistinguishable pulsed-field gel electrophoresis patterns may be shared among different cooling towers and persist over time.     

Associated Liver Partition and Portal Vein Ligation (ALPPS) vs Selective Portal Vein Ligation (PVL) for Staged Hepatectomy in a Rat Model. Similar Regenerative Response?

Associated liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a two-stage hepatectomy technique which can be associated with a hypertrophic stimulus on the future liver remnant (FLR) stronger than other techniques–such as portal vein ligation (PVL). However, the reason of such hypertrophy is still unclear, but it is suggested that liver transection combined with portal vein ligation (ALPPS) during the first stage of this technique may play a key role. The aim of this study is to compare the hypertrophic stimulus on the FLR and the clinical changes associated with both ALPPS and PVL in a rat surgical model. For this purpose, three groups of SD rats were used, namely ALPPS (n = 30), PVL (n = 30) and sham-treated (n = 30). The second stage of ALPPS (hepatectomy of the atrophic lobes), was performed at day 8. Blood and FLR samples were collected at 1, 24, 48 hours, 8 days and 12 weeks after the surgeries. ALPPS provoked a greater degree of hypertrophy of the FLR than the PVL at 48 hours and 8 days (p<0.05). The molecular pattern was also different, with the highest expression of IL-1β at 24h, IL-6 at 8 days, and HGF and TNF-α at 48 hours and 8 days (p<0.05). ALPPS also brought about a mild proliferative stimulus at 12 weeks, with a higher expression of HGF and TGF-β (p<0.05) than PVL. Clinically, ALPPS caused a significant liver damage during the first 48 hours, with a recovery of liver function at day 8. In conclusion, ALPPS seems to induce higher functional hypertrophy on the FLR than PVL at day 8. Such regenerative response seems to be leaded by a complex interaction between pro-mitogenic (IL-6, HGF, TNF-α) and antiproliferative (IL1-β and TGF-β) cytokines.     

Annual cycle of stored spermatozoa within the ovaries of Helicolenus dactylopterus dactylopterus (Teleostei, Scorpaenidae)

The aim of this work was to analyse the ultrastructure of storage crypts and stored spermatozoa, and to describe changes during the annual reproductive cycle of the bluemouth Helicolenus dactylopterus dactylopterus , which has internal fertilization and a zygoparous mode of reproduction. Spermatozoa had elongated heads and long midpieces, two characteristics which are thought to be fairly advanced and correlated with internal fertilization, as is the case of the bluemouth. A remarkable spermatozoon feature was the retention of a significant quantity of cytoplasm around the head, a condition that appeared to be related to nourishment during the long storage period, up to 10 months in the intraovarian crystal structures of the female. Male sex cells' protection against the female immune system was ensured by junctional complexes between the crypt cells composed of tight junctions and desmosomes.     

Bacterial Metabolism of 2,6-Xylenol

Strain DM1, a Mycobacterium sp. that utilizes 2,6-xylenol, 2,3,6-trimethylphenol, and o-cresol as sources of carbon and energy, was isolated. Intact cells of Mycobacterium strain DM1 grown with 2,6-xylenol cooxidized 2,4,6-trimethylphenol to 2,4,6-trimethylresorcinol. 4-Chloro-3,5-dimethylphenol prevents 2,6-xylenol from being totally degraded; it was quantitatively converted to 2,6-dimethylhydroquinone by resting cells. 2,6-Dimethylhydroquinone, citraconate, and an unidentified metabolite were detected as products of 2,6-xylenol oxidation in cells that were partially inactivated by EDTA. Under oxygen limitation, 2,6-dimethylhy-droquinone, citraconate, and an unidentified metabolite were released during 2,6-xylenol turnover by resting cells. Cell extracts of 2,6-xylenol-grown cells contained a 2,6-dimethylhydroquinone-converting enzyme. When supplemented with NADH, cell extracts catalyzed the reduction of 2,6-dimethyl-3-hydroxyquinone to 2,6-dimethyl-3-hydroxyhydroquinone. Since a citraconase was also demonstrated in cell extracts, a new metabolic pathway with 2,6-dimethyl-3-hydroxyhydroquinone as the ring fission substrate is proposed.     

Effect of Yeast Hulls on Stuck and Sluggish Wine Fermentations: Importance of the Lipid Component

The effect of yeast hulls (yeast ghosts) on sluggish or stuck white wine fermentations was studied. The enhancing effect on yeast growth and fermentation rate displayed by the hulls was shown to be similar to the effect provided by lipid extract from the same hulls. Unsaturated fatty acids and sterols were incorporated into the yeast from lipid extracts during fermentation carried out under oxygen-limited conditions. Adsorption of toxic medium-chain fatty acid (decanoic acid) onto the yeast hulls took place through a dialysis membrane. However, when the hulls were placed inside a dialysis bag, the increase in yeast growth and fermentation rate seen when freely suspended hulls were used did not occur. Accordingly, the effect of yeast hulls in preventing stuck fermentations cannot be attributed only to the adsorption and consequent removal of medium-chain fatty acids from the juice.     

Selective uptake of cholesteryl ester from high density lipoproteins by plasma membranes of adipose tissue

The interaction between high density lipoproteins (HDL) and adipose tissue is an important pathway for cholesterol and cholesteryl ester flux. In intact fat cells, a disproportionately greater net uptake of cholesteryl ester occurs subsequent to lipoprotein binding than would have been predicted from a consideration of holoparticle uptake alone. To characterize the early events in this process, cholesteryl hexadecyl ether, a nonmetabolizable, accumulative marker of cholesteryl ester, was incorporated into canine HDL2, and its uptake by omental adipocyte plasma membranes was measured in relation to the binding of HDL2, which in this animal species is enriched in apolipoprotein A-I and free of apolipoprotein E. The dose-response profile for HDL2 binding was consistent with a single lipoprotein binding site at all concentrations of HDL2, whereas uptake of cholesteryl ester from HDL2 was biphasic, suggesting a high affinity site at low HDL2 concentrations and a low affinity site at high lipoprotein concentrations. Pronase treatment stimulated binding twofold and this was accompanied by a parallel twofold stimulation of cholesteryl ester uptake. EDTA, on the other hand, reduced binding and uptake of cholesteryl ester by 20%, indicating partial dependence upon divalent cations. The proportion of HDL2 cholesteryl ester accumulated by plasma membranes relative to HDL2 protein bound was not altered by either pronase or EDTA, despite the fact that these agents had opposite effects upon binding. In dissociation studies, a portion of membrane-associated HDL2 did not equilibrate with exogenous HDL2 and a greater proportion of the cholesteryl ester failed to dissociate. A stepwise mechanism for cholesteryl ester uptake, involving (i) saturable, high affinity HDL2 binding to cell surface sites, (ii) vectoral, HDL2 concentration-dependent delivery of cholesteryl ester to the membrane, and (iii) cholesteryl ester sequestration into a nonexchangeable membrane compartment, appears to be independent of metabolic energy or cell processing.