Relative binding affinity of novel steroids to androgen receptors in hamster prostate

The in vivo and in vitro antiandrogenic activity of four aromatic esters 10a-10d, one aliphatic ester 10e based on the pregna-4,16-diene-6, 20-dione structure and two aromatic 17c, 17d and two aliphatic valeroyloxy esters 17a, 17b based on the more saturated 4-pregnene-6,20-dione skeleton was examined. The biological activity of steroids 9, 10a-10e and 17a-17d, was determined using prostate glands from gonadectomized adult male golden hamsters. In the in vitro studies, the relative binding affinity of these steroids to cytoplasmic androgen receptor (AR) of hamster prostate was determined from, the corresponding IC50 values obtained from the competitive binding plots. The standards dihydrotestosterone (DHT) and cyproterone (CA) acetate used have displaced [3H]DHT from the AR with an IC50 value of 3.2 and 4.4 nM respectively. All steroidal compounds synthesized in this study showed a binding affinity for the androgen receptor, present in the cytosol from prostate hamster; compounds 10a-10c showed the highest affinities for this receptor. The in vivo experiments showed that all steroidal derivatives were subcutaneously active, since they decreased the weight of the prostate gland in gonadectomized hamsters treated with DHT, and are antagonists for the androgen receptor since they block the DHT-induced prostate weight gain. The derivatives having the more conjugated 4,16-pregnadiene-6, 20-dione system (10a-10c) exhibited a higher antiandrogenic activity than the corresponding steroids (17a-17d) based on the more saturated 4-pregnene-6,20-dione system.

Interaction of bacterial endotoxine (lipopolysaccharide) with latex particles: application to latex agglutination immunoassays

The latex agglutination immunoassay technique uses polymer colloids as carriers for antibodies or antigens to enhance the immunological reaction. In this work, the interaction of a lipopolysaccharide (LPS) of Brucella Melitensis with two conventional latexes has been studied. Some experiments on the physical adsorption of the LPS onto these polystyrene beads have been performed and several complexes with different coverage degrees were obtained by modifying the incubation conditions. Regarding the application in the development of diagnostic test systems, it is advisable to study the latex-LPS complexes from an electrokinetic and colloidal stability point of view. The complexes were electrokinetically characterized by measuring the electrophoretic mobility under different redispersion conditions. The colloidal stability was determined by simple turbidity measurements. Experimental and theoretical data have been employed to study the molecular disposition of the LPS in the latex particle surface to compare with the outer membrane of bacterial cells. Latex complexes covered by different LPS amounts showed high colloidal stability and adequate immunoreactivity that remains for a long time period.

Prevalence Data of Rickettsia slovaca and Other SFG Rickettsiae Species in Dermacentor marginatus in the Southeastern Iberian Peninsula

In southern Spain, Dermacentor marginatus ticks can be infected with several genospecies of spotted fever Group (SFG) Rickettsia. We developed a nested polymerase chain reaction assay by using a species-specific probe targeting the ompA gene to detect and differentiate between the two groups of rickettsiae previously described in D. marginatus. SFG rickettsia has been detected in 85.15% of ticks studied (26.7% of positives have been to R. slovaca, the causative agent of TIBOLA-DEBONEL, and 73.3% to SFG rickettsia closely related to strains RpA4-JL-02-DnS14-DnS28).

Search for the invisible decay of neutrons with KamLAND

The Kamioka Liquid scintillator Anti-Neutrino Detector is used in a search for single neutron or two-neutron intranuclear disappearance that would produce holes in the -shell energy level of (12)C nuclei. Such holes could be created as a result of nucleon decay into invisible modes (inv), e.g., n--> 3v or nn--> 2v. The deexcitation of the corresponding daughter nucleus results in a sequence of space and time-correlated events observable in the liquid scintillator detector. We report on new limits for one- and two-neutron disappearance: tau(n--> inv) > 5.8 x 10(29) years and tau (nn--> inv) > 1.4 x 10(30) years at 90% C.L. These results represent an improvement of factors of approximately 3 and >10(4) and over previous experiments.

Determinant role of membrane helices in K ATP channel gating

The ATP-sensitive K(+) (K(ATP)) channels couple chemical signals to cellular activity, in which the control of channel opening and closure (i.e., channel gating) is crucial. Transmembrane helices play an important role in channel gating. Here we report that the gating of Kir6.2, the core subunit of pancreatic and cardiac K(ATP) channels, can be switched by manipulating the interaction between two residues located in transmembrane domains (TM) 1 and 2 of the channel protein. The Kir6.2 channel is gated by ATP and proton, which inhibit and activate the channel, respectively. The channel gating involves two residues, namely, Thr71 and Cys166, located at the interface of the TM1 and TM2. Creation of electrostatic attraction between these sites reverses the channel gating, which makes the ATP an activator and proton an inhibitor of the channel. Electrostatic repulsion with two acidic residues retains or even enhances the wild-type channel gating. A similar switch of the pH-dependent channel gating was observed in the Kir2.1 channel, which is normally pH- insensitive. Thus, the manner in which the TM1 and TM2 helices interact appears to determine whether the channels are open or closed following ligand binding.

Experimental investigation of geologically produced antineutrinos with KamLAND

The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.

A positive association of peripheral arterial occlusive disease (PAD) andChlamydophila (Clamydia) pneumoniae

The relationship between Chlamydophila pneumoniae (Cp) infection and peripheral arterial occlusive disease (PAD) was studied by analyzing clinical samples from 95 patients with PAD and 100 controls. The following investigations were conducted: IgG and IgA against lipopolysaccharide (LPS) and against purified Cp-specific antigens from elementary bodies (EB) with ELISA; anti-EB IgG, with MIF; Cp DNA in arterial biopsy and peripheral blood mononuclear cells with heminested PCR; LPS with ELISA; and bacteria culture in HEp-2 cells from arterial biopsy. A significantly higher ratio of anti-EB IgG was detected in patients. There were no significant differences in anti-LPS IgG, anti-LPS IgA and anti-EB IgA between cases and controls. Cp DNA findings in the vascular wall biopsy showed significant differences between cases and controls. We obtained results that significantly involve Cp infection with PAD through the detection of anti-EB IgG from serum and bacterial DNA from arterial biopsy.

Antioxidant enzymes and tissue regeneration in Eurythoe complanata (Polychaeta: Amphinomidae) exposed to used vehicle crankcase oil

Polychaetes, Eurythoe complanata, from the Gulf of Cariaco,Venezuela, were exposed to 0.3, 1.6, and 3.3% water-soluble fraction (WSF) of used crankcase oil during 15 and 21 days. The antioxidant enzymes glutathione peroxidase (GPX), glutathione reductase (GR), catalase (CAT), and glutathione-S-transferase (GST) were assayed in the body wall tissue. Furthermore, after chemical exposure, the polychaetes were cut into equal halves; then wound healing and the number of regenerated body segments were recorded periodically. GST activity was affected by all the experimental treatments, with activity increasing with WSF concentrations. GPx activity was altered for the contamination period. GR and CAT activities rose in response to increasing WSF concentrations, and were higher for long-term than for short-term exposures. The wound healing of the transected body regions was retarded by WSF exposure. WSF affected the tissue regeneration, which was almost abolished at 3.3% WSF. The exposure period did not affect the tissue-repairing responses. Alteration of GST in contaminated organisms suggested equivalent changes in detoxication of bioaccumulated organic contaminants. The variation of GR and CAT suggests induction of oxidative stress that could reduce the ability of WSF-exposed worms to repair damaged tissue.

Sequence characterization of Tomato leaf curl Sinaloa virus and Tomato severe leaf curl virus: Phylogeny of New World begomoviruses and detection of recombination

Diseases caused by begomoviruses (family Geminiviridae, genus Begomovirus) constitute a serious constraint to tomato production in Nicaragua. In this study, the complete nucleotide (nt) sequences of the DNA-A and DNA-B components were determined for the first time for Tomato leaf curl Sinaloa virus (ToLCSinV). In addition, the complete nt sequence was determined for the DNA-A component of two isolates of Tomato severe leaf curl virus (ToSLCV). The genome organization of ToLCSinV and ToSLCV was identical to the bipartite genomes of other begomoviruses described from the Americas. A phylogenetic analysis of DNA-A including 45 begomovirus species showed that the indigenous begomoviruses of the New World can be divided into three major clades and an intermediate group: AbMV clade, SLCV clade, "Brazil clade", and BGYMV group. Phylogenetic analyses of the DNA-A and DNA-B components and their open reading frames indicated that ToLCSinV and ToSLCV belong to different clades: ToLCSinV to the AbMV clade, and ToSLCV to the SLCV clade. The two Nicaraguan isolates of ToSLCV showed a close relationship with ToSLCV from Guatemala (ToSLCV-[GT96-1]) and Tomato chino La Paz virus (ToChLPV), but differed significantly in the AV1 and AC1 regions, respectively. Computer-based predictions indicated that recombination with another begomovirus had taken place within AV1 of ToSLCV dividing this species into two strains. A high probability was also found that ToChLPV is involved in the evolution of ToSLCV.

Assessment of liver function during extracorporeal membrane oxygenation in the non-heart beating donor swine

INTRODUCTION

Although the use of non-heart beating donors (NHBD) could bridge the widening gap between organ demand and supply, its application to liver transplantation is limited due to warm ischemia (WI), biliary tree injury, and inadequate organ assessment. Warm blood reperfusion using extracorporeal membrane oxygenation (ECMO) can be a suitable option to reduce WI in organs from NHBD, allowing one to determine hepatic flow characteristics and bile production and facilitating assessment of organ viability.

METHODS

This work evaluates the use of warm blood veno-arterial ECMO reperfusion in NHBD swine. Systemic and hepatic hemodynamics, bile, urine, and mixed venous blood were measured. After baseline data collection, 10 kU heparin was given intravenously followed by 1 g KCl to elicit cardiac arrest (CA). ECMO was started after 30 or 60 minutes of CA and kept running for 120 minutes.

RESULTS

One-way repeated measures analysis of variance (ANOVA) with Tukey test analysis was used within a group. Two-way ANOVA was used between groups. ECMO can restore venous SO2 and pH in both groups; the values were close to baseline in the 30-minute CA group. Also, in this group, bile production was > 65% from baseline early during reperfusion and its value was lower in the longer CA group < 55% (P < .001). Aspartate aminotransferase (AST) was doubled at the end of ECMO support in the 60-minute CA group (P < .05).

CONCLUSION

In this preheparinized NHBD swine model, ECMO support restores liver perfusion, oxygenation, and bile production after 60 minutes of CA. Quantification and analysis of bile production could be a determinant of liver function during ECMO resuscitation, and it may be a predictor of graft viability before transplantation.

Measurement of neutrino oscillation with KamLAND: evidence of spectral distortion

We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.

The influence of cellular seeding density in the microencapsulation of hybridoma cells

The aim of this study was to assess the influence of different seeding densities on the function of hybridoma cells (clone 1B5, IgG 2alpha) producing an anti-angiogenic monoclonal antibody (mAb), microencapsulated using a high-voltage electrostatic field. Viable cells were microencapsulated in alginate/poly-L-lysine/alginate (APA) capsules and maintained in tissue culture. Cellular growth rates, production and release of mAb from the capsules were assessed. This study shows that hybridoma cells survive, proliferate and remain functionally competent for over one month in vitro after microencapsulation in APA capsules generated in an electrostatic field. However, the cell seeding density had to be at least 10(7) cells/ml for the microencapsulated cells to be viable and to produce and release mAb through the capsule membrane. The maximum monoclonal antibody concentration in this culture was 29.1 microg/ml by day 17, with a tendency to increase, but capsule breakage impeded the follow-up of this determination.

Is sensitization with nicotinamide and carbogen dependent on nicotinamide concentration at the time of irradiation?

PURPOSE

To determine whether tumour radiosensitization and the therapeutic benefit of administering carbogen with nicotinamide depend upon irradiating at the time of peak drug concentration.

MATERIALS AND METHODS

Local tumour control of CaNT tumours in CBA mice and acute skin reactions in albino WHT mice were assessed after treatment with 10 X-ray fractions in air, carbogen alone or combined with 0.1, 0.2 or 0.5 mg g(-1) nicotinamide, injected 15, 30 or 60 min before irradiation. Plasma and tumour drug pharmacokinetics were performed.

RESULTS

Nicotinamide was rapidly taken up into tumours; a six- and threefold higher concentration was obtained with 0.5 mg g(-1) compared with 0.1 and 0.2 mg g(-1), respectively. Tumour, but not skin, radiosensitization increased as the dose of nicotinamide increased (p = 0.03), but at each dose level there was no significant difference in radiosensitivity when irradiations were done at or after the time of peak concentration. An almost eightfold increase in plasma levels increased tumour enhancement ratios from 1.74 to 1.92 (p < 0.0001). In tumours all schedules gave significant enhancement relative to carbogen alone (p < or = 0.04).

CONCLUSIONS

Tumour and skin radiosensitivity was independent of time of nicotinamide administration. Higher drug concentrations were not mirrored by proportionally higher enhancement ratios. Lower plasma levels than previously suggested significantly enhanced tumour radiosensitivity relative to carbogen alone. The clinical implications of these findings are discussed.

A threonine residue (Thr71) at the intracellular end of the M1 helix plays a critical role in the gating of Kir6.2 channels by intracellular ATP and protons

ATP-sensitive K+ (K(ATP)) channels are known to be gated by several intracellular molecules, but the gating mechanisms remain unclear. To understand the relationship of channel gating to ligand binding, we studied Kir6.2 channel gating by ATP and protons, which inhibit and activate the channel, respectively. We have previously shown that a threonine residue (Thr71) is critical for the pH sensitivity of Kir6.2 channel. If this site is involved in channel gating rather than ligand binding, it should affect channel gating by both ATP and proton. To test this hypothesis we performed a mutation analysis. Site-specific mutations of Thr71 to a bulky residue reduced the ATP sensitivity by >100-fold and eliminated the pH sensitivity. Single-channel activity of these mutants was stabilized at the open state with no detectable rundown. Mutations to a small amino acid had little effect on the ATP and pH sensitivities. Mutations to intermediate amino acids reduced but did not abolish the ATP and pH sensitivities. Hydrophobicity is not critical, as both polar and nonpolar amino acids are found in each group. Mutation to a positively charged lysine markedly exacerbated the pH- but not ATP-sensitivity, whereas mutation to glutamate moderately reduced ATP and pH sensitivities. These results indicate that the residue mass is critical for Kir6.2 channel gating, a mass that should be below 120 daltons with no charge. The existence of such a site as Thr71 involved in channel gating by both ATP and proton suggests that channel gating in the K(ATP) channel likely is separate from ligand binding.

Extracts from plants used in Mexican traditional medicine activate Ca(2+)-dependent chloride channels in Xenopus laevis oocytes

The two-electrode voltage-clamp technique was employed to investigate the effects of chloroform-methanol (1:1) extracts derived from five medicinal plants on Xenopus laevis oocytes. When evaluated at concentrations of 1 to 500 microg/ml, the extracts prepared from the aerial parts of Baccharis heterophylla H.B.K (Asteraceae), Chenopodium murale L. (Chenopodiaceae), Desmodium grahami Gray (Leguminosae) and Solanum rostratum Dun (Solanaceae) produced concentration-dependent oscillatory inward currents in the oocytes, while the extract of Gentiana spathacea did not induce any response. The reversal potential of the currents elicited by the active extracts was -17 +/- 2 mV and was similar to the chloride equilibrium potential in oocytes. These ionic responses were independent of extracellular calcium. However, they were eliminated by overnight incubation with BAPTA-AM (10 microM), suggesting that the currents were dependent on intracellular Ca2+ increase. Thus the plant extracts activate the typical oscillatory Ca(2+)-dependent Cl- currents generated in the Xenopus oocyte membrane more probably via a mechanism that involves release of Ca2+ from intracellular reservoirs. These observations suggest that Xenopus oocyte electrophysiological recording constitutes a suitable assay for the study of the mechanisms of action of herbal medicines.