Telomeres and cancer: from crisis to stability to crisis to stability

Telomere attrition unleashes genomic instability, promoting cancer development. Once established, however, the malignant clone often re-establishes genomic stability through overexpression of telomerase. In two papers, one in this issue of Cell and one in the subsequent issue, DePinho and colleagues explore the consequences of telomerase re-expression and its validity as a therapeutic target in mouse models of cancer.     

Tribute to Tinbergen: Questions and How to Answer Them

Despite the major advances that have occurred in the study of animal behaviour in the 50 years since the publication of Tinbergen's (ZeitschriftfürTierpsychologie, 20, 1963, 410) ‘Aims and Methods’ paper, the framework he outlined still remains the best way we have of guiding and organizing behavioural research. His distinction between four different types of question – adaptation, phylogeny, immediate causal mechanism and development – and his insistence on being clear on what would count as answers to each of them are still as good an introduction to the subject today as they ever were.     

Postconditioning and Anticonditioning: Possibilities to Interfere to Evoked Apoptosis

The aim of this study was to validate the ability of postconditioning, used 2 days after kainate intoxication, to protect selectively vulnerable hippocampal CA1 neurons against delayed neuronal death. Kainic acid (8 mg/kg, i.p.) was used to induce neurodegeneration of pyramidal CA1 neurons in rat hippocampus. Fluoro Jade B, the specific marker of neurodegeneration, and NeuN, a specific neuronal marker were used for visualization of changes 7 days after intoxication without and with delayed postconditioning (norepinephrine, 3.1 μmol/kg i.p., 2 days after kainate administration) and anticonditioning (Extract of Ginkgo biloba, 40 mg/kg p.o used simultaneously with kainate). Morris water maze was used on 6th and 7th day after kainate to test learning and memory capabilities of animals. Our results confirm that postconditioning if used at right time and with optimal intensity is able to prevent delayed neuronal death initiated not only by ischemia but kainate intoxication, too. The protective effect of repeated stress–postconditioning was suppressed if extract of Ginkgo biloba (EGb 761, 40 mg/kg p.o.) has been administered together with kainic acid. It seems that combination of lethal stress and antioxidant treatment blocks the activation of endogenous protecting mechanism known as ischemic tolerance, aggravates neurodegeneration and, after repeated stress is able to cause cumulative damage. This observation could be very valuable in situation when the aim of treatment is elimination of unwanted cell population from the organism.     

Cell growth: how to grow and where to grow

Root hairs provide a model system for studying tip growth in plants. The recent cloning of genes required for tip growth has shed new light on the link between ionic regulation, cell wall assembly and the cytoskeleton in cell growth.     

Antibodies to phospholipids and liposomes: binding of antibodies to cells

Binding of two monoclonal anti-liposome antibodies to the surface of cultured murine peritoneal macrophages was investigated by indirect immunofluorescence and enzyme-linked immunosorbent assay. Neither antibody bound to cultures of freshly explanted, nonadherent macrophages, but immunoreactivity was observed following cell adherence to tissue culture plastic. Fluorescent microscopic evaluation revealed heterogeneity in staining patterns of the antibodies on adherent cells. Binding both to viable and fixed adherent macrophages was observed even after a 10,000-fold dilution of antibody. Treatment of adherent macrophage cultures with trypsin increased antibody binding. Further treatment of trypsinized-macrophages with alkaline phosphatase or neuraminidase did not affect antibody binding, but phospholipase D and, to a greater extent, phospholipase C resulted in a marked decrease in cellular binding. The data indicate that antibodies produced against liposomes appear to bind to surface phospholipids of macrophages, but binding can be influenced by the physiological state of the macrophage and overlying cell surface proteins.     

Burning-Feet Syndrome: Case Due to Malabsorption and Responding to Riboflavine

A woman with the burning-feet syndrome was found on investigation to have malabsorption. The syndrome responded rapidly to intramuscular injections of 6 mg. of riboflavine daily. It is suggested that deficiency of this substance, due to malabsorption and aggravated by a defective diet and repeated pregnancies, was responsible for the syndrome in this case.