Molecular imaging of cell death in vivo by a novel small molecule probe

Apoptosis has a role in many medical disorders, therefore assessment of apoptosis in vivo can be highly useful for diagnosis, follow-up and evaluation of treatment efficacy. ApoSense is a novel technology, comprising low molecular-weight probes, specifically designed for imaging of cell death in vivo. In the current study we present targeting and imaging of cell death both in vitro and in vivo, utilizing NST-732, a member of the ApoSense family, comprising a fluorophore and a fluorine atom, for both fluorescent and future positron emission tomography (PET) studies using an ¹⁸F label, respectively. In vitro, NST-732 manifested selective and rapid accumulation within various cell types undergoing apoptosis. Its uptake was blocked by caspase inhibition, and occurred from the early stages of the apoptotic process, in parallel to binding of Annexin-V, caspase activation and alterations in mitochondrial membrane potential. In vivo, NST-732 manifested selective uptake into cells undergoing cell-death in several clinically-relevant models in rodents: (i) Cell-death induced in lymphoma by irradiation; (ii) Renal ischemia/reperfusion; (iii) Cerebral stroke. Uptake of NST-732 was well-correlated with histopathological assessment of cell-death. NST-732 therefore represents a novel class of small-molecule detectors of apoptosis, with potential useful applications in imaging of the cell death process both in vitro and in vivo. Revital Aloya and Anat Shirvan are equal contribution to the paper     

Prophage induction by ultraviolet light in Acinetobacter calcoaceticus

UV-induction of prophage P78 of Acinetobacter calcoaceticus increased with the UV-dose given to the lysogenic strain from the spontaneous induction frequency of about 0.8% to a maximal frequency of 10%. This 10- to 20-fold increase of induction frequency, as measured by the number of infective centres, was accompanied by a 1000-fold increase in the yield of free phage. This effect was probably due to an increase in burst size under the conditions of lysogenic induction. Unusually, the lysogen was more resistant to UV-irradiation than the corresponding non-lysogenic strain.     

Diversity of β-Globin Mutations in Israeli Ethnic Groups Reflects Recent Historic Events

We characterized nearly 500 β-thalassemia genes from the Israeli population representing a variety of ethnic subgroups. We found 28 different mutations in the β-globin gene, including three mutations (β^S, β^C, and β^O-Arab) causing hemoglobinopathies. Marked genetic heterogeneity was observed in both the Arab (20 mutations) and Jewish (17 mutations) populations. On the other hand, two ethnic isolates—Druze and Samaritans—had a single mutation each. Fifteen of the β-thalassemia alleles are Mediterranean in type, 5 originated in Kurdistan, 2 are of Indian origin, and 2 sporadic alleles came from Europe. Only one mutant allele—nonsense codon 37—appears to be indigenous to Israel. While human habitation in Israel dates back to early prehistory, the present-day spectrum of β-globin mutations can be largely explained by migration events that occurred in the past millennium.     

Surface-motility induction,attraction and hitchhiking between bacterial species promote dispersal on solid surfaces

The ability to move on solid surfaces provides ecological advantages for bacteria, yet many bacterial species lack this trait. We found that Xanthomonas spp. overcome this limitation by making use of proficient motile bacteria in their vicinity. Using X. perforans and Paenibacillus vortex as models, we show that X. perforans induces surface motility, attracts proficient motile bacteria and ‘rides'' them for dispersal. In addition, X. perforans was able to restore surface motility of strains that lost this mode of motility under multiple growth cycles in the lab. The described interaction occurred both on agar plates and tomato leaves and was observed between several xanthomonads and motile bacterial species. Thus, suggesting that this motility induction and hitchhiking strategy might be widespread and ecologically important. This study provides an example as to how bacteria can rely on the abilities of their neighboring species for their own benefit, signifying the importance of a communal organization for fitness.     

Non-random chromosomal aberrations in a complex leukaemic clone of a Bloom's syndrome patient

Summary Bloom's syndrome is one of the congenital disorders known to have increased frequency of acute leukaemia. The complex cytogenetic findings in the leukaemic cells of a 39-year-old male with Bloom's syndrome are described. These included a translocation t(7;17), missing 7q and 17p, a reciprocal translocation t(4;22); del 3q, del 8q22, del 20q, missing 12 and missing Y. In the same patient a missing Y had been noted 10 years previously in 15% of his peripheral blood lymphocytes.     

Identification and isolation of rat bone marrow-derived mast cells using the mast cell-specific monoclonal antibody AA4.

Previous studies of mast cell maturation, structure, and function have been hampered by the lack of mast cell-specific markers. In this study, using a well-characterized mast cell-specific monoclonal antibody, MAb AA4, mast cells from rat bone marrow in various stages of maturation were isolated and characterized. The very immature mast cells, which have not been previously described, contained few granules and would not be recognized as mast cells by standard cytological methods. Pure populations of mast cells were isolated from the bone marrow using MAb AA4-conjugated magnetic beads. The same stages of maturation were observed in the isolated mast cells as were seen in the unfractionated bone marrow. All of these cells were immunopositive for the alpha-subunit of Fc epsilon RI, IgE, and c-kit, confirming their identity as mast cells. By direct counting of immunolabled cells and by flow cytometry, approximately 2.4% of the cells in the bone marrow are mast cells. Staining with toluidine blue and berberine sulfate, as well as RT-PCR of the cells, indicates that these cells are connective tissue-type mast cells. The use of immunological methods for identification of mast cell precursors should facilitate the study of these cells. (J Histochem Cytochem 49:219-228, 2001)     

Probing the active site of homoserine trans-succinylase

Homoserine trans-succinylase is the first enzyme in methionine biosynthesis of Escherichia coli and catalyzes the activation of homoserine via a succinylation reaction. The in vivo activity of this enzyme is subject to tight regulation by several mechanisms, including repression and activation of gene expression, feedback inhibition, temperature regulation and proteolysis. This complex regulation reflects the key role of this enzyme in bacterial metabolism. Here, we demonstrate--using proteomics and high-resolution mass spectrometry--that succinyl is covalently bound to one of the two adjacent lysine residues at positions 45 and 46. Replacing these lysine residues by alanine abolished the enzymatic activity. These findings position the lysine residues, one of which is conserved, at the active site.     

Urban Chagas disease in children and women in primary care centres in Buenos Aires,Argentina

The primary objective of this study was to estimate the prevalence of this disease inwomen of childbearing age and children treated at health centres in underservicedareas of the city of Buenos Aires. Demographic and Chagas disease status data werecollected. Samples for Chagas disease serology were obtained on filter paper and thereactive results were confirmed with conventional samples. A total of 1,786 subjectswere screened and 73 positive screening results were obtained: 17 were from childrenand 56 were from women. The Trypanosoma cruzi infection risk wasgreater in those individuals who had relatives with Chagas disease, who rememberseeing kissing bugs, who were of Bolivian nationality or were born in the Argentineprovince of Santiago del Estero. The overall prevalence of Chagas disease was 4.08%.Due to migration, Chagas disease is currently predominantly urban. The observedprevalence requires health programme activities that are aimed at urban children andtheir mothers. Most children were infected congenitally, which reinforces the needfor Chagas disease screening of all pregnant women and their babies in Argentina. Theactive search for new cases is important because the appropriate treatment inchildren has a high cure rate.