A Glycomic Approach Towards Identification of Signature Molecules in CD34+ Haematopoietic Stem Cells from Umbilical Cord Blood.

Umbilical cord blood (UCB) is a powerful storehouse for normal CD34+ haematopoietic stem cells (HSCs), often used for allogeneic bone marrow (BM) transplantation in malignant and non-malignant diseases. The glycomic especially the sialoglycomic aspect of these HSCs has been unravelled in this study. Cell surface expression of the glycans with the related enzymatic activities has been compared with the BM of childhood acute lymphoblastic leukaemia, a common BM-associated malignancy. An enhanced cell surface expression of α2,3-linked sialic acid, P- and E-selectins, and intercellular adhesion molecule along with reduced expression of L-selectin distinguishes CD34+ HSCs of UCB from leukaemic samples. More importantly, high expression of O-acetylated sialoglycoproteins, a hallmark of lymphoblasts, is drastically reduced in the CD34+ HSCs of UCB and is substantiated by the low activity of sialylate-O-acetyltransferase and high sialidase activity. In contrast, a significant variation is evident in the expression of sialic acid, α2,6-linked sialic acids, and the sialyltransferase activity. Taken together, these studies indicate a few signature molecules, forming a unique glycomic template, which may be a potential indicator, reassuring the normal profile of these stem cells, to be used for future transplantation.

Effect of oxidative stress on the growth of magnetic particles in Magnetospirillum magneticum

Individual magnetosome-containing magnetic mineral particles (MMP) from magnetotactic bacteria grow rapidly such that only a small fraction (5%) of all magnetosomes contain dwarf (< or =20 nm) MMP. Studies of the developmental stages in the growth of MMP are difficult due to the absence of techniques to separate dwarf from mature particles and because the former are sensitive to extraction procedures. Here, O2 stress was used to inhibit MMP expression in Magnetospirillum magneticum strain AMB-1. In addition, defined growth conditions not requiring chemical monitoring or manipulation of the gas composition during growth resulted in the production of cells containing high numbers of dwarf MMP. Cells exposed to different incubation treatments and cells with dwarf MMP were compared to cells with normal MMP with respect to growth, respiration, iron content, and relative magnetite load (RML). The cells were examined by electron microscopy, low temperature magnetometry, X-ray diffraction (XRD), and Mössbauer spectroscopy. In the 0-110 microM O2(aq) range, growth was positively correlated with [O2] and negatively correlated with RML. Most MMP formed during exponential growth of the cells. At 50-100 microM O2(aq) with stirring (150 rpm) and 30% O2 loss during incubation, MMP expression was strongly inhibited whereas MMP nucleation was not. Cells highly enriched (~95%) in dwarf MMP were obtained at the end of the exponential phase in stirred (150 rpm) cultures containing 45 microM O2(aq). Only one dwarf MMP formed in each MMP vesicle and the chain arrangement was largely preserved. O2-stress-induced dwarf MMP consisted of non-euhedral spheroids (~25 nm) that were similar in shape and size to immature MMP from normal cells. They consisted solely of magnetite, with a single domain signature, no superparamagnetic behavior, and magnetic signatures, Fe(II)/Fe(III) ratios, and XRD patterns very similar to those of mature MMP. These results show that O2 stress in liquid cultures amended with an inorganic redox buffer (S2O3 2-/S0) can be used to produce abundant dwarf MMP that are good proxies for studying MMP development (AU)

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Effects of magnetic interactions in antiferromagnetic ferrihydrite particles.

The effects of magnetic interactions in the magnetic properties of six-line ferrihydrite particles were investigated by studying the behavior of aggregated versus coated particles. Four different coating agents (sugar, alginate, lactate and ascorbate) were employed in order to obtain dispersed particles and prevent particle agglomeration; one sub-sample was allowed to dry with no coating agent. The five sets of ferrihydrite particles were from the same batch and the size was estimated as 3.6 ± 0.4 nm in length. Low temperature magnetization, ac susceptibility and Mössbauer spectroscopy data showed contrasting blocking temperatures for uncoated and coated samples with a decrease of T(P) from about 50 K to 12 K, respectively. The contributions from magnetic interactions were recognized in magnetic measurements and the effective anisotropy constant for non-interacting ferrihydrite was estimated as (100 ± 10) × 10(3) J m(-3). Overall, employing sugar and alginate as coating agents was more successful in preventing particle aggregation and magnetic interactions. In contrast, ascorbate and lactate were unsuitable due to the chemical reaction between the coating agent and ferrihydrite surface.

Red cell morphology in leukemia, hypoplastic anemia and myelodysplastic syndrome.

Leukemic patients of different classifications are associated with anemia. Such clinical conditions are often referred to as refractory anemia, paraoxymal nocturnal hemoglobinuria, hemolytic uremia and autoimmune hemolytic anemia, all of which could be categorized as the cancer cachexia. In the present work, we have studied the overall morphology of intact red cells in different leukemic patients along with patients of hypoplastic anemia (HPA) by scanning electron microscopy. We have also studied the ultrastructure of the red cell surface membranes by transmission electron microscopy. For all experiments, erythrocytes from normal individuals served as controls. We have shown direct evidence of the altered red cell (RBC) membrane morphology irrespective of the hemoglobin status of the patients which includes (1) presence of large central holes in RBCs of acute myeloid leukemia (AML), (2) presence of thorn- and horn-like structure in RBCs of acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia (CML) and (3) flaccid appearance of RBCs in chronic lymphocytic leukemia (CLL) patients. A mixture of the above mentioned structures were found in the red cells of patients suffering from myelodysplastic syndrome (MDS) and in case of patients of HPA the RBCs lost the normal biconcave structures. TEM studies revealed presence of pores with diameters ranging from 100 to 200nm on the RBC membrane surface of myeloid leukemia with AML being the most prominent among others. Such pathophysiological alterations of the RBC morphology in leukemic patients could be identified as characteristic signature of the onset of anemia associated with the disease.

A reexamination of human-induced environmental change within the Lake Pátzcuaro Basin, Michoacán, Mexico.

This paper presents 2,000 years of settlement and land use within the Lake Pátzcuaro Basin, Mexico. Three findings challenge the conclusions of previous research. We show (i) that initial land degradation was caused by settlement, not by agriculture; (ii) that population density inversely correlates with erosion; and (iii) that land degradation was associated with European Conquest but not from the introduction of the Euro-agro suite. Instead, demographic collapse caused by European-introduced disease prevented human-generated landscapes from being maintained, resulting in widespread degradation. These findings support the use of indigenous landscape technology for modern conservation if past failings can be resolved.