Combination of gastrin-releasing peptide antagonist with cytotoxic agents produces synergistic inhibition of growth of human experimental colon cancers

We investigated the efficacy of a powerful antagonist of bombesin/gastrin-releasing peptide (BN/GRP) RC-3940-II administered as a single agent or in combination with cytotoxic agents on the growth of HT-29, HCT-116 and HCT-15 human colon cancer in vitro and in vivo. GRP-receptor mRNA and protein were found in all three cell lines tested. Exposure of HT-29 cells to 10 μM RC-3940-II led to an increase in the number of cells blocked in S phase and G₂/M and cells with lower G₀/G₁ DNA content. Similar changes on the cell cycle traverse of HT-29 cells could also be seen at lower concentrations of RC-3940-II (1 μM) after pretreatment with 100 nM GRP (14–27), indicating a dose-dependent mechanism of action based on the blockage of BN/GRP induced proliferation of tumor cells at lower concentrations. Daily in vivo treatment with BN/GRP antagonist RC-3940-II decreased the volume of HT-29, HCT-116 and HCT-15 tumors xenografted into athymic nude mice by 25 to 67% (p < 0.005). Combined treatment with RC-3940-II and chemotherapeutic agents 5-FU and irinotecan resulted in a synergistic tumor growth suppression of HT-29, HCT-116 and HCT-15 xenografts by 43% to 78%. In HT-29 and HCT-116 xenografts the inhibition for the combinations of RC-3940-II and irinotecan vs. single substances (p < 0.05) was significantly greater. These findings support the use of RC-3940-II as an anticancer agent and may help to design clinical trials using RC-3940-II in combinations with cytotoxic agents.     

Wnt/beta-catenin signaling controls development of the blood-brain barrier

The blood–brain barrier (BBB) is confined to the endothelium of brain capillaries and is indispensable for fluid homeostasis and neuronal function. In this study, we show that endothelial Wnt/β-catenin (β-cat) signaling regulates induction and maintenance of BBB characteristics during embryonic and postnatal development. Endothelial specific stabilization of β-cat in vivo enhances barrier maturation, whereas inactivation of β-cat causes significant down-regulation of claudin3 (Cldn3), up-regulation of plamalemma vesicle-associated protein, and BBB breakdown. Stabilization of β-cat in primary brain endothelial cells (ECs) in vitro by N-terminal truncation or Wnt3a treatment increases Cldn3 expression, BBB-type tight junction formation, and a BBB characteristic gene signature. Loss of β-cat or inhibition of its signaling abrogates this effect. Furthermore, stabilization of β-cat also increased Cldn3 and barrier properties in nonbrain-derived ECs. These findings may open new therapeutic avenues to modulate endothelial barrier function and to limit the devastating effects of BBB breakdown.     

Exposure and mortality in a cohort of German nuclear power workers

A historical cohort study of German nuclear power workers was set up to investigate the overall and cancer mortality risk related to a long-term low-level exposure to ionising radiation. The cohort was part of an international collaborative study whose pooled analyses were carried out at the International Agency for Research on Cancer (IARC), Lyon, and published recently. Due to delays in data collection, data from the German cohort were not included in these analyses. This cohort includes 4,844 employees who worked in any of 10 nuclear power plants, between 1 January 1991 and 31 December 1997. Sixty-eight deaths among men were observed in 31,000 person years, and none among women. Standardized mortality ratios (SMRs) were computed for all causes of death, all cancers, cardiovascular diseases, external causes, and all other causes. Overall, a strong healthy worker effect was observed (all-cause SMR = 0.54, 95% CI 0.42–0.67), and no increase in total cancer mortality was seen (SMR = 0.66, 95% CI 0.43–0.95). These results are in line with and complement IARC results. Figures are yet too small for stable risk estimates and further work is therefore under way to include more power plants, and to extend the follow-up until the year 2005.     

Ceramic-based multisite microelectrode arrays for simultaneous measures of choline and acetylcholine in CNS

A ceramic-based microelectrode array (MEA) with enzyme coatings for the accurate measurement of acetylcholine (ACh) in brain tissues is presented. Novel design features allow for self-referencing recordings for improved limits of detection and highly selective measurements of ACh and choline (Ch), simultaneously. Design and fabrication features also result in minimal tissue damage during implantation and improved enzyme coatings due to isolated recording sites. In these studies we have used a recombinant human acetylcholinesterase enzyme coating, which has better reproducibility than other commercially available enzymes. The precisely patterned recording site dimensions, low limit of detection (0.2 micro M) and fast response time ( approximately 1s) allow for second-by-second measurements of ACh and Ch in brain tissues. An electropolymerized meta-phenylenediamine (mPD) layer was used to exclude interfering substances from being recorded at the platinum recording sites. Our studies support that the mPD layer was stable for over 24h under in vitro and in vivo recording conditions. In addition, our work supports that the current configuration of the MEAs produces a robust design, which is suited for measures of ACh and Ch in rat brain.     

Are Polyommatus hispana and Polyommatus slovacus bivoltine Polyommatus coridon (Lepidoptera: Lycaenidae)? The discriminatory value of genetics in taxonomy

Taxonomic confusion exists in several sibling species groups. The Polyommatus coridon species complex (Chalk Hill Blues) serves as a model group of sibling species in which genetic analyses provide suitable means for taxonomic clarification. We studied the allozyme patterns of the two described bivoltine species of this complex, Polyommatus hispana and Polyommatus slovacus, and compared them to the two genetic lineages of the univoltine P. coridon. P. hispana is well distinguished from P. coridon (genetic distance: 0.081), and most probably is a sibling species that has evolved during glacial isolation on the Iberian Peninsula. P. slovacus is genetically indistinguishable from the eastern, Pontic–Mediterranean lineage of P. coridon; therefore we suggest that it represents a local bivoltine population only. Since the spring generation of P. slovacus was much less common than the summer generation and showed less genetic diversity, it is probable that uni-/bivoltinism is a dimorphism affecting only part of the whole population. We suggest that the higher genetic diversity of the second generation may be a consequence of gene flow from adjacent single-brooded populations.     

Substantial Rise in the Prevalence of Lyme Borreliosis Spirochetes in a Region of Western Germany over a 10-Year Period

More than a decade after a study on the transmission cycle of Borrelia burgdorferi sensu lato in the Siebengebirge, a nature reserve near Bonn, Germany, questing nymphal and adult Ixodes ricinus ticks were collected again in three selected areas of the same low mountain range and examined for infection with B. burgdorferi sensu lato. Between May and October 2001, a total of 1,754 ticks were collected by blanket dragging; 374 ticks were analyzed for B. burgdorferi sensu lato by both an immunofluorescence assay (IFA) and at least two different PCR tests, whereas 171 ticks were analyzed by PCR only. By combining all assays, an average of 14% of the ticks tested positive for B. burgdorferi sensu lato, 5.5, 15.8, and 21.8% in the three collection areas. Of the nymphs and adults examined, 12.9 and 21.1%, respectively, were found to be spirochete infected. A lower total infection prevalence was obtained by IFA (14.4%) than by a nested PCR approach (16.5%), but both were higher than that obtained by a simple PCR approach (11.9%). Compared with data collected over a decade ago, the mean infection prevalence of B. burgdorferi sensu lato in the ticks was significantly higher for all three biotopes, whereas a similar pattern of habitat-specific infection prevalence was observed. Genotyping of B. burgdorferi sensu lato revealed high relative prevalences of B. valaisiana (identified in 43.1% of infected ticks) and B. garinii (32.3%), whereas B. afzelii (12.3%) and B. burgdorferi sensu stricto (1.5%) were relatively rare. We conclude that B. burgdorferi sensu lato infection has increased in this region over the last 15 years due to presently unknown changes in ecological conditions, perhaps related to climate change or wildlife management.     

Mate sampling by female barking treefrogs (Hyla gratiosa)

Despite intense interest in mate choice, relatively little isknown about how individuals sample prospective mates. Indeed,a key issue is whether females sample males or simply matewith the first male encountered. We investigated mate samplingby female barking treefrogs (Hyla gratiosa). Females choosingmates in natural choruses did not move between males but insteadmated with the first male they approached closely. Most femalesmated with the male closest to them at the start of their mate-choiceprocess, and females were more likely to mate with the closest male when the distance to other males was large. These observationsare consistent with the hypothesis that females do not samplepotential mates but instead mate with the first male they distinguishfrom the rest of the chorus. To test this initial detectionhypothesis, we conducted a playback experiment in which weoffered females a choice between two calls, one of which was detectable above the background chorus sound at the female'srelease point, and one of which became detectable only as femalesmoved toward the initially detectable call. Females did notprefer the initially detectable call, thus ruling out the initialdetection hypothesis and implicating sampling of potentialmates by females. Based on the behavior of females in natural choruses, we hypothesize that females approach the chorus, moveto locations where they are able to detect the calls of severalmales simultaneously, and choose a mate from among these malesat some distance from the males. Such simultaneous samplingmay be common in lekking and chorusing species, which havebeen the subjects of many studies of sexual selection.