Protective role of unconjugated bilirubin on complement-mediated hepatocytolysis

Hyperbilirubinemia and complement-mediated immune attack on hepatocyte membrane are common features of certain hepatic diseases. To assess whether unconjugated bilirubin (UB) counteracts complement-mediated hepatocytolysis, we first generated a rabbit polyclonal antibody (Ab) against rat hepatocyte plasma membrane (RHPM). An assay performed with isolated rat hepatocytes in the presence of the polyclonal Ab and rat serum as complement donor demonstrated that UB inhibits cell lysis, as lactate dehydrogenase release into the medium was inhibited by the pigment in a dose-dependent manner. Immunofluorescence microscopy studies showed that UB significantly attenuates the binding of C3 to the hepatocyte-Ab complex. Further enzyme immunoassay studies showed that UB interferes the binding of C1q to purified anti-RHPM IgG, also in a dose-dependent manner. A dot-blot assay showed that [14C]-UB binds to C1q and human serum albumin (HSA) to a similar extent. A differential spectrum analysis of UB in the presence of C1q further confirmed that the pigment interacts with this protein. In conclusion, we demonstrated an inhibitory action of UB on complement-mediated Ab-induced hepatocytolysis, this action being evidenced at pathophysiological pigment concentrations (171 microM and higher). A direct binding of the pigment to C1q is likely involved.     

Enantioselective synthesis and vanilloid activity evaluation of 1-beta-(p-methoxycinnamoyl)polygodial, an antinociceptive compound from Drymis winteri barks

A simple strategy is outlined for preparation of the antinociceptive 1-beta-(p-methoxycinnamoyl)polygodial, isolated from Drymis winteri barks. The synthesized compound showed vanilloid activity.     

Design of Magnetic Polymeric Particles as a Stimulus-Responsive System for Gastric Antimicrobial Therapy

The treatment of peptic ulcers induced by H. pylori remains challenging due to the deep mucous layer location of bacteria preventing antimicrobial drug access. The present work aimed to design and evaluate in vitro dual responsive (both pH and magnetic field-sensitive) polymeric magnetic particles loaded with amoxicillin as a smart drug carrier for deep mucous layer penetration and in situ drug release. Magnetite particles were produced by the co-precipitation method and subsequently coated with the Eudragit^®S100 and amoxicillin by using the spray-drying technique. The physicochemical characterization of the obtained particles was carried out by optical and scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption/desorption isotherms, and vibrating sample magnetometry. Additionally, drug release tests and antibacterial activity tests were evaluated in vitro. Microparticles presented 17.2?±?0.4 μm in size and their final composition was 4.3?±?1.5% of amoxicillin, 87.0?±?2.3% of Eudragit, and 9.0?±?0.3% of magnetite. They were both pH and magnetic field responsive while presenting antimicrobial activity. On one side, magnetic field responsiveness of particles is expected to prompt them to reach bacterium niche in deep mucous layer by means of magnetic forces. On the other side, pH responsiveness is expected to enable drug release in the neutral pH of the deep mucous layer, preventing undesired delivery in the acidic gastric lumen. Smart microparticles were designed presenting both pH and magnetic field responsiveness as well as antimicrobial activity. These may be promising assets for peptic ulcer treatment.     

A first-principles study of Ni<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>Pd<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> (n = 1 − 5) clusters

A first-principle investigation of structures and properties of Ni _n Pd _n (n=1-5) clusters is presented. For this study, the linear combination of Gaussian-type orbitals auxiliary density functional theory (LCGTO-ADFT) method has been employed. In order to determine the lowest energy structures, several isomers in different spin multiplicities were studied, for each cluster size. Initial structures, for which successive geometry optimization was computed without any constrain, were taken along Born–Oppenheimer molecular dynamics (BOMD) trajectories. To discriminate between minima and transition state structures, harmonic frequency analyses were performed at the optimized structures. Ground state structures, bond lengths, harmonic frequencies, dissociation energy, ionization potential, electron affinity and spin density plots are presented. This work demonstrates, that the Pd atoms prefer to allocate on the surface of the cluster structures whose core is formed by the 3d TM atoms type. Moreover, it has been observed that the ground-state structure spin multiplicity increases as the system size grows. The results of this study contribute to gain insight into how structures and energy properties change with cluster size in bimetallic Pd-based alloys.     

Sex difference in thermal preference of adult mice does not depend on presence of the gonads

Background

The thermoneutral zone (TNZ) is a species-specific range of ambient temperature (T _a), at which mammals can maintain a constant body temperature with the lowest metabolic rate. The TNZ for an adult mouse is between 26 and 34 °C. Interestingly, female mice prefer a higher T _a than male mice although the underlying mechanism for this sex difference is unknown. Here, we tested whether gonadal hormones are dominant factors controlling temperature preference in male and female mice.

Methods

We performed a temperature preference test in which 10-week-old gonadectomized and sham-operated male and female C57BL/6J mice were allowed to choose to reside at the thermoneutral cage of 29 °C or an experimental cage of 26, 29, or 32 °C.

Results

All mice preferred a T _a higher than 26 °C, especially in the inactive phase. Choosing between 29 and 32 °C, female mice resided more at 32 °C while male mice had no preference between the temperatures. Hence, the preferred T _a for female mice was significantly higher (0.9?±?0.2 °C) than that for male mice. However, gonadectomy did not influence the T _a preference.

Conclusions

Female mice prefer a warmer environment than male mice, a difference not affected by gonadectomy. This suggests that thermal-sensing mechanisms may be influenced by sex-specific pathways other than gonadal factors or that the thermoregulatory set point has already been determined prior to puberty.

     

Species distribution models predict temporal but not spatial variation in forest growth

Bioclimate envelope models have been widely used to illustrate the discrepancy between current species distributions and their potential habitat under climate change. However, the realism and correct interpretation of such projections has been the subject of considerable discussion. Here, we investigate whether climate suitability predictions correlate to tree growth, measured in permanent inventory plots and inferred from tree‐ring records. We use the ensemble classifier RandomForest and species occurrence data from ~200,000 inventory plots to build species distribution models for four important European forestry species: Norway spruce, Scots pine, European beech, and pedunculate oak. We then correlate climate‐based habitat suitability with volume measurements from ~50‐year‐old stands, available from ~11,000 inventory plots. Secondly, habitat projections based on annual historical climate are compared with ring width from ~300 tree‐ring chronologies. Our working hypothesis is that habitat suitability projections from species distribution models should to some degree be associated with temporal or spatial variation in these growth records. We find that the habitat projections are uncorrelated with spatial growth records (inventory plot data), but they do predict interannual variation in tree‐ring width, with an average correlation of .22. Correlation coefficients for individual chronologies range from values as high as .82 or as low as ?.31. We conclude that tree responses to projected climate change are highly site‐specific and that local suitability of a species for reforestation is difficult to predict. That said, projected increase or decrease in climatic suitability may be interpreted as an average expectation of increased or reduced growth over larger geographic scales.     

Spectrophotometer-aided evaluation of cyanogenic potential in white clover (Trifolium repens L.)

In comparison with ordinary methods of colorimetric evaluation of cyanogenic potential based on visual evaluation of the alkaline picrate reaction, a spectrophotometer-aided method could be more accurate (since it determines the exact amount of hydrogen cyanide released by the plant material), and less time-consuming as it can be performed on bulk material rather than on a number of individual plants. Ten white clover populations were evaluated by a spectrophotometer-aided method and by two visual evaluation criteria. All methods indicated the presence of large variation between populations. Visual methods gave almost identical results and allowed only for the distinction between cyanogenic and substantially acyanogenic populations. The results were only moderately consistent with those obtained by the spectrophotometer-aided method, which could detect the presence of variation also between cyanogenic populations. The effects of various incubation times (from 4 to 48 h) and of the addition of β-glucosidase on hydrogen cyanide release were also investigated. Comparable results for ranking of populations could be obtained over a range of incubation times, but at least 24 h were needed for a reliable estimation of the hydrogen cyanide produced by plants. The addition of enzyme did not increase the released cyanide. The effect of season and/or conditions of evaluation was marked on mean cyanogenic potential but limited on ranking of populations. Copyright © 2000 John Wiley & Sons, Ltd.     

The SR Ca2+ ATPase of the Antarctic scallop Adamussium colbecki: cold adaptation and heavy metal effects

Cell calcium is accumulated in intracellular stores by sarco-endoplasmic reticulum Ca²⁺ ATPases functionally interacting with the membrane lipid environment. Cold adaptations of membrane lipids in Antarctic Sea organisms suggest possible adaptive effects also on sarco-endoplasmic reticulum Ca²⁺ ATPases. We investigated the SR Ca²⁺ ATPase of an Antarctic scallop, Adamussium colbecki, by characterising the enzyme activity and studying temperature effects. Ca²⁺ ATPase, assayed by following ATP hydrolysis, was thapsigargin- and vanadate-sensitive, showed maximum activity under 2 μM Ca²⁺, 200 mM KCl and pH 7.2, and had a K _M for ATP of 22 ± 7 μM. Temperature effects showed an Arrhenius inversion between −1.8 and 0°C, indicating cold adaptation, an Arrhenius break at 10°C, and a collapse above 20°C. A. colbecki accumulates high amounts of cadmium in the digestive gland; heavy metal effects on sarco-endoplasmic reticulum Ca²⁺ ATPases were therefore tested, finding an IC₅₀ = 0.9 μM for Hg²⁺ and 3 μM for Cd²⁺. Finally, SDS-PAGE analysis showed a main band at about 100 kDa, which was identified as sarco-endoplasmic reticulum Ca²⁺ ATPase after trypsin digestion, and accounted for 60% total protein. Accepted: 10 December 1998     

Purification and Characterization of Novel Antifungal Compounds from the Sourdough Lactobacillus plantarum Strain 21B

Sourdough lactic acid bacteria were selected for antifungal activity by a conidial germination assay. The 10-fold-concentrated culture filtrate of Lactobacillus plantarum 21B grown in wheat flour hydrolysate almost completely inhibited Eurotium repens IBT18000, Eurotium rubrum FTDC3228, Penicillium corylophilum IBT6978, Penicillium roqueforti IBT18687, Penicillium expansum IDM/FS2, Endomyces fibuliger IBT605 and IDM3812, Aspergillus niger FTDC3227 and IDM1, Aspergillus flavus FTDC3226, Monilia sitophila IDM/FS5, and Fusarium graminearum IDM623. The nonconcentrated culture filtrate of L. plantarum 21B grown in whole wheat flour hydrolysate had similar inhibitory activity. The activity was fungicidal. Calcium propionate at 3 mg ml⁻¹ was not effective under the same assay conditions, while sodium benzoate caused inhibition similar to L. plantarum 21B. After extraction with ethyl acetate, preparative silica gel thin-layer chromatography, and chromatographic and spectroscopic analyses, novel antifungal compounds such as phenyllactic and 4-hydroxy-phenyllactic acids were identified in the culture filtrate of L. plantarum 21B. Phenyllactic acid was contained at the highest concentration in the bacterial culture filtrate and had the highest activity. It inhibited all the fungi tested at a concentration of 50 mg ml⁻¹ except for P. roqueforti IBT18687 and P. corylophilum IBT6978 (inhibitory concentration, 166 mg ml⁻¹). L. plantarum 20B, which showed high antimold activity, was also selected. Preliminary studies showed that phenyllactic and 4-hydroxy-phenyllactic acids were also contained in the bacterial culture filtrate of strain 20B. Growth of A. niger FTDC3227 occurred after 2 days in breads started with Saccharomyces cerevisiae 141 alone or with S. cerevisiae and Lactobacillus brevis 1D, an unselected but acidifying lactic acid bacterium, while the onset of fungal growth was delayed for 7 days in bread started with S. cerevisiae and selected L. plantarum 21B.     

Biological Control Potential of Wolbachia -infected Versus Uninfected Wasps: Laboratory and Greenhouse Evaluation of Trichogramma cordubensis and T. deion Strains

The effects of thelytoky-inducing Wolbachia ( &#102 -proteobacteria) on Trichogramma cordubensis and T. deion (Hymenoptera, Trichogrammatidae) were studied in laboratory and greenhouse conditions. One infected (thelytokous, all female) line of each wasp species was compared with its conspecific uninfected (arrhenotokous, sexual) counterpart for several fecundity and dispersal traits. Arrhenotokous lines had a higher fecundity than their thelytokous counterparts, which suggests that Wolbachia negatively affect the fecundity of Trichogramma females. The arrhenotokous females dispersed more in the laboratory than their thelytokous counterparts. In the greenhouse, the opposite effect or no difference between lines was found, indicating that the laboratory set-up used to measure dispersal is not useful to predict relative dispersal of the females in the greenhouse. Calculations show that by releasing 100 adult wasps of both lines, thus including arrhenotokous males in the sexual line, more eggs are parasitized by the thelytokous wasps. Therefore, in spite of their lower individual female fecundity, thelytokous lines have a better potential for biological control than their arrhenotokous counterparts.