Abrogation of the radiation-induced G2 checkpoint by the staurosporine derivative UCN-01 is associated with radiosensitisation in a subset of colorectal tumour cell lines

Ionising radiation is commonly used in the treatment of colorectal cancer. Tumour cells with mutant p53 undergo cell cycle arrest at G2/M after ionising radiation and evidence suggests that abrogation of this G2 arrest can lead to a premature, aberrant mitosis, thus enhancing ionising radiation-induced cell killing. The G2 checkpoint inhibitor UCN-01 was thus investigated to determine whether it would abrogate the G2 checkpoint induced by 5 Gy ionising radiation in a range of colorectal tumour cell lines. Data presented show that, at doses that are alone non-toxic to the cells, UCN-01 inhibits the ionising radiation-induced G2 checkpoint in five colorectal tumour cell lines with mutant p53. The ability of UCN-01 to sensitise cells to ionising radiation-induced growth inhibition and apoptosis was also investigated and UCN-01 was found to radiosensitise two out of five cell lines. These results were confirmed by long-term colony forming efficiency studies. These results demonstrate that abrogation of the ionising radiation-induced G2 checkpoint is not necessarily associated with sensitisation to ionising radiation, however, some colorectal tumour cell lines can be radiosensitised by UCN-01. Although the mechanism of radiosensitisation is not clear, this may still be an important treatment strategy

Subcellular localization and tissue specific expression of amidase 1 from Arabidopsis thaliana

Amidase 1 (AMI1) from Arabidopsis thaliana converts indole-3-acetamide (IAM), into indole-3-acetic acid (IAA). AMI1 is part of a small isogene family comprising seven members in A. thaliana encoding proteins which share a conserved glycine- and serine-rich amidase-signature. One member of this family has been characterized as an N-acylethanolamine-cleaving fatty acid amidohydrolase (FAAH) and two other members are part of the preprotein translocon of the outer envelope of chloroplasts (Toc complex) or mitochondria (Tom complex) and presumably lack enzymatic activity. Among the hitherto characterized proteins of this family, AMI1 is the only member with indole-3-acetamide hydrolase activity, and IAM is the preferred substrate while N-acylethanolamines and oleamide are not hydrolyzed significantly, thus suggesting a role of AMI1 in auxin biosynthesis. Whereas the enzymatic function of AMI1 has been determined in vitro, the subcellular localization of the enzyme remained unclear. By using different GFP-fusion constructs and an A. thaliana transient expression system, we show a cytoplasmic localization of AMI1. In addition, RT-PCR and anti-amidase antisera were used to examine tissue specific expression of AMI1 at the transcriptional and translational level, respectively. AMI1-expression is strongest in places of highest IAA content in the plant. Thus, it is concluded that AMI1 may be involved in de novo IAA synthesis in A. thaliana

Pharmacologic Inhibition of the TGF-β Type I Receptor Kinase Has Anabolic and Anti-Catabolic Effects on Bone

During development, growth factors and hormones cooperate to establish the unique sizes, shapes and material properties of individual bones. Among these, TGF-β has been shown to developmentally regulate bone mass and bone matrix properties. However, the mechanisms that control postnatal skeletal integrity in a dynamic biological and mechanical environment are distinct from those that regulate bone development. In addition, despite advances in understanding the roles of TGF-β signaling in osteoblasts and osteoclasts, the net effects of altered postnatal TGF-β signaling on bone remain unclear. To examine the role of TGF-β in the maintenance of the postnatal skeleton, we evaluated the effects of pharmacological inhibition of the TGF-β type I receptor (TβRI) kinase on bone mass, architecture and material properties. Inhibition of TβRI function increased bone mass and multiple aspects of bone quality, including trabecular bone architecture and macro-mechanical behavior of vertebral bone. TβRI inhibitors achieved these effects by increasing osteoblast differentiation and bone formation, while reducing osteoclast differentiation and bone resorption. Furthermore, they induced the expression of Runx2 and EphB4, which promote osteoblast differentiation, and ephrinB2, which antagonizes osteoclast differentiation. Through these anabolic and anti-catabolic effects, TβRI inhibitors coordinate changes in multiple bone parameters, including bone mass, architecture, matrix mineral concentration and material properties, that collectively increase bone fracture resistance. Therefore, TβRI inhibitors may be effective in treating conditions of skeletal fragility

Effects of Red-Cell Storage Duration on Patients Undergoing Cardiac Surgery

Some observational studies have reported that transfusion of red-cell units that have been stored for more than 2 to 3 weeks is associated with serious, even fatal, adverse events. Patients undergoingcardiac surgery may be especially vulnerable to the adverse effects of transfusion

The molecular logic of endocannabinoid signalling

The endocannabinoids are a family of lipid messengers that engage the cell surface receptors that are targeted by Δ9-tetrahydrocannabinol, the active principle in marijuana (Cannabis). They are made on demand through cleavage of membrane precursors and are involved in various short-range signalling processes. In the brain, they combine with CB1 cannabinoid receptors on axon terminals to regulate ion channel activity and neurotransmitter release. Their ability to modulate synaptic efficacy has a wide range of functional consequences and provides unique therapeutic possibilities. © 2003, Nature Publishing Group. All rights reserved

Odor-quality perception and its representation in the olfactory bulb

Understanding how patterns of neuronal activity contribute to odor perception will shed light on how external information is translated by the nervous system. Previously, large-scale lesioning of the nasal epithelium or the main olfactory bulb (OB) has been reported to produce only mild deficits in odor detection and discrimination. This has led to the idea that much of the glomerular activity within the OB is redundant and that odor processing can be achieved with a limited amount of sensory input. Here we have combined behavioural experiments and in vivo imaging to directly examine the relationship between OB activity and odor perception in mice with disrupted olfactory representations. Water-deprived mice (C57BL/6J, P30-70) were trained to discriminate a monomolecular rewarded odor (S+) from an unrewarded odor (S-) using a go/no-go behavioural paradigm. Subsequently, under pentobarbitone anesthesia (1.1mg/g b.w.), S+ and S- odor - evoked activity on the dorsal surface of the OB was recorded using standard intrinsic-signal imaging. Mice then received a nasal flush of either ZnSO4 (8.4%) to partially ablate sensory input, or NaCl (9%, sham treatment). Three to five days later, mice were assessed on discrimination of an unfamiliar odor pair and then on recognition of the pre-treatment S+ and S- odors. Mice were then re-anesthetised and a second imaging session was carried out to assess the representation of S+ and S- odors. We find that ZnSO4 - treated mice required significantly more trials to discriminate rewarded unfamiliar odors accurately (≥ 80% correct) than sham treated mice (336 ± 39.9, n = 5 mice vs 166.6 ± 44.4 trials, n = 6 mice; p 0.05) and showed no difference in their mean discrimination times (p > 0.05). For unrewarded familiar odorants, ZnSO4-treated mice showed significantly poorer recognition than sham mice (71 ± 7.4 vs 90 ± 2.8%, p < 0.05) and an initially significant discrimination deficit of rewarded familiar odorants (71.1 ± 7.3 vs 89.8 ± 2.2% p < 0.05; first 20 trials). Comparison of pre- and post-treatment imaging data revealed that the integrity of glomerular-activity patterns observed in the second session correlated with the ability to recognize S+ and S- odors (r = 0.74, p < 0.05, n = 13 mice). In contrast to previous lesion studies, our data show that perceived odor quality and the ability to distinguish odorants depends critically upon the number and integrity of functional input channels to the OB