The NMR solution structure of human epidermal growth factor (hEGF) at physiological pH and its interactions with suramin

Human epidermal growth factor (hEGF) induces the proliferation, differentiation and survival of various cell types including tumor-derived cells. Generally, hEGF performs its biological function by binding to a specific receptor (hEGFR) on the cell surface, thereby inducing signal transduction. Suramin, a polysulfonated naphthylurea that acts as a growth factor blocker, exhibits antiproliferative activity against non-small cell lung cancer (NSCLC) cells that overexpress EGFR on the cell surface. We determined the solution structure of hEGF under physiological conditions and investigated the interaction of suramin with hEGF using isothermal titration calorimetry and NMR spectroscopy techniques. The solution structure of hEGF presented in this paper is different from the bound form of hEGF present in the crystal structure of the 2:2 EGF-EGFR complex because its C-tail contains a hydrophobic core. This conformational difference supports the hypothesis that hEGF undergoes a conformational change when it binds to hEGFR and subsequently induces signal transduction. Based on the docking structure of the hEGF-suramin complex, we demonstrated how suramin blocks hEGF by binding to its receptor binding site (the C-terminal region around Arg45) and inhibits the crucial conformational change.

Diffusion tensor group tractography of the corpus callosum in clinically isolated syndrome

BACKGROUND AND PURPOSE

Many studies have observed atrophy and abnormal diffusion within the CC in MS. However, few studies have addressed whether such abnormalities appear at the earliest stage of MS, especially in CIS. In this study, we aimed to investigate the CC integrity and patterns of CC abnormalities in CIS with diffusion tensor group tractography.

MATERIALS AND METHODS

First, probability maps of the entire CC and its subregions (genu, body, and splenium) were created from 19 healthy subjects. Then these probability maps were used to evaluate diffusion within the entire CC and its segments in 19 patients with CIS. Five indices, including the midsagittal CC area, FA, MD, λ(1), and λ(23), were used to characterize CC integrity.

RESULTS

Significant differences were found between patients with CIS and healthy controls in the entire CC and its segments. For the entire CC, patients with CIS had a significantly lower midsagittal CC area and FA, higher MD and λ(23), with a trend toward higher λ(1). These 4 diffusion measures were correlated with T2 lesion volume. Moreover, abnormal white matter integrity was present in subregions of the CC; there was a robust significant increase in λ(23) in the body and splenium and no difference in λ(1) in the genu.

CONCLUSIONS

Our results suggest that atrophy and abnormal diffusion inside the CC appear at the stage of CIS and the severity of damage in the genu is milder than that in the body and splenium.

Constructing defined chromosome segmental duplications in maize

We describe the production of chromosome segmental duplications and deletions of defined length in maize. The method utilizes a collection of previously isolated transposon-induced reciprocal translocations with sequence-defined breakpoints. These balanced translocations involve a first common breakpoint at the site of transposon Ac/fAc insertions on chromosome 1S, and a second variable endpoint elsewhere in the genome. Stocks containing translocations with different endpoints on the same chromosome arms were crossed together to generate heterozygous combinations. Subsequent meiotic segregation generates gametes that contain the original balanced translocations, or pairs of translocation chromosomes that are genetically unbalanced; i.e., they contain a duplication or deletion of the affected segment. Self-pollination produces progeny plants that are genetically balanced, or that contain 0 to 4 copies of the affected segment. The chromosome constitution of progeny plants can be determined using PCR primers flanking the translocation breakpoints. In addition, plants segregating genetically unbalanced gametes exhibit significant pollen grain abnormalities and thus can be easily detected in the field. In this way, we constructed 4 different segmental tetrasomic stocks involving genomic regions of approximately 7.8, 18.7, 21, and 42.6 Mb on chromosomes 5S, 5L, 5L, and 4L, respectively. FISH analysis using specific probes located within the affected segments confirms their aneuploid composition. These and similar lines containing precisely defined segmental duplications and deletions may be useful to study the genetic impact of gene dosage.

Predicting the radiation exposure of terrestrial wildlife in the Chernobyl exclusion zone: an international comparison of approaches

There is now general acknowledgement that there is a requirement to demonstrate that species other than humans are protected from anthropogenic releases of radioactivity. A number of approaches have been developed for estimating the exposure of wildlife and some of these are being used to conduct regulatory assessments. There is a requirement to compare the outputs of such approaches against available data sets to ensure that they are robust and fit for purpose. In this paper we describe the application of seven approaches for predicting the whole-body ((90)Sr, (137)Cs, (241)Am and Pu isotope) activity concentrations and absorbed dose rates for a range of terrestrial species within the Chernobyl exclusion zone. Predictions are compared against available measurement data, including estimates of external dose rate recorded by thermoluminescent dosimeters attached to rodent species. Potential reasons for differences between predictions between the various approaches and the available data are explored.