Human embryonic stem cell (hES) colonies display a higher degree of spontaneous differentiation when passaged at lower densities

Summary Human embryonic stem (hES) cells require cooperative interactions with each other for their survival. Previously, the size of hES cell clumps has been reported to be an important factor in determining their viability during routine serial passage. However, the effects of seeding density of the hES cell clumps per se have not yet been investigated. Therefore, this study attempted to compare the level of spontaneous differentiation of hES colonies passaged at two different split ratios (1∶3 and 1∶8) of a single confluent well of a six-well dish. After 7 d of in vitro culture following serial passage, hES colonies were assigned into three grades according to their degree of spontaneous differentiation: (1) Grade A, which was completely or mostly undifferentiated; (2) grade B, which was partially differentiated; and (3) grade C, which was mostly differentiated. Assessment of the degree of spontaneous differentiation was based on morphological observations under bright-field and phase-contrast microscopy, as well as on immunocytochemical staining for the pluripotency markers SSEA-3 and TRA-1-81. We observed that, at a split ratio of 1∶3, the percentages of grade A, B, and C colonies were 89.5, 8.8, and 1.7%, respectively. This was significantly different from the corresponding values of 52.7, 31.3, and 16.0%, respectively, obtained at a split ratio of 1∶8. Hence, our results indicated that a lower passage density led to a higher degree of spontaneous differentiation of hES colonies.     

Short-term experiments on ion transport by seedlings and excised roots : technique and validity

The absorption of K⁺ by excised roots of barley (Hordeum vulgare L. cv California Mariout) has been systematically compared with that of entire, undisturbed seedlings. Some experiments have also been done with wheat (Triticum aestivum L.) and an amphiploid obtained from a cross between it and salt-tolerant tall wheatgrass (Lophopyrum elongatum Host Löve [syn. Agropyron elongatum Host]). For all three genotypes, the rate of K⁺ absorption measured in a 20-min period was identical for entire 8-d-old seedlings and their excised roots within the experimental error. Manipulation gentler than root excision, viz. careful transfer of seedlings from one experimental solution to another, was also without effect on the rate of K⁺ absorption. Absorption of K⁺ measured by assay of its ⁸⁶Rb label in the tissue was identical with that measured by K⁺ depletion of the experimental solutions assayed chemically. For the plant materials and conditions of these experiments, the excised root technique for studying ion transport into roots is validated. The advantages of the technique, and findings differing from the present ones, are discussed.     

Mathematical modeling in metal metabolism: Overview and perspectives

A review of mathematical modeling in metal metabolism is presented. Both endogenous and exogenous metals are considered. Four classes of methods are considered: Petri nets, multi-agent systems, determinist models based on differential equations and stochastic models. For each, a basic theoretical background is given, then examples of applications are given, detailed and commented. Advantages and disadvantages of each class of model are presented. A special attention is given to determinist differential equation models, since almost all models belong to this class.     

Investigation of the extent of contamination of heavy metals in agricultural soil using statistical analyses and contamination indices

To examine the level of contamination of Eshghabad region, Neyshabur, the concentration of heavy metals in soil was measured. For this purpose, 37 samples were taken from surface soil and the total concentration of heavy elements was measured by inductively coupled plasma (ICP). The mean concentration of Pb, Ni, Cu, Zn, and Fe was obtained to be 195, 87.3, 22.8, 274.8, and 2.5%, respectively. Using five valid indicators, the intensity of metal contamination in soil was calculated and compared. Furthermore, using statistical analyses, the relationships between the elements, their origins, and the spatial distribution of metals across various stations were investigated. The results indicated that the mean value of all of the studied metals (except for iron and copper) is greater than the mean concentration of metals in the Earth's crust. The indicators showed very high contamination for lead, while low to medium contamination for other elements of interest in the farming soils of the region. Statistical analyses indicated that there is a relatively similar contamination intensity across all of the studied stations. Considering the quality standards, the soils of this region are threatened by contamination of lead.     

Bioactive phenolic compounds from a medicinal lichen, Usnea longissima

Natural products, longissiminone A (1) and longissiminone B (2), were isolated along with a known compound, glutinol (3), from a medicinal lichen, Usnea longissima. The structures of compounds 1 and 2 were determined with the help of spectroscopic studies. Compound 1 was found to possess potent anti-inflammatory activity in a cell-based contemporary assay. Cytotoxicity activity measured by cell viability assay showed 100% viability in the presence of 200 microg/mL conc. of these compounds.     

Variation in Blood and Colorectal Epithelia’s Key Trace Elements Along with Expression of Mismatch Repair Proteins from Localized and Metastatic Colorectal Cancer Patients

Colorectal cancer (CRC) is an increasingly common medical issue affecting millions worldwide, and contribution of the body’s trace elements to CRC is arguable. The concentrations and buffered status of selenium, iron, copper, zinc, and phosphorus in blood and large intestinal tissues of CRC patients are, respectively, variable and vital for cell physiology. The aim of this study was to assess selenium, iron, copper, zinc, and phosphorus variations in blood and colorectal epithelia along with examining the expression of mismatch repair proteins in CRC patients with/without metastasis for potential diagnosis/therapy. Concentrations of selenium, iron, copper, zinc, and phosphorus in blood of healthy versus CRC patients and colorectal epithelia (adenocarcinomatous versus non-adenocarcinomatous/control) were measured in 40 CRC patients (55.87 ± 11.9 years old) with/without metastasis before surgery using ICP-OES. Mismatch repair (MMR) protein expression was analyzed through histopathological/immunohistochemistry assays, which was sparse in 5 CRC patient’s colorectal tissues (12%). Compared with healthy individuals, blood and colorectal tissue’s levels of phosphorus, copper, and iron were significantly higher in the CRC patients, and more pronounced in metastatic CRC patients; conversely, blood and colorectal tissue’s selenium levels were significantly lower in metastatic patients. Unlike blood zinc, cancerous colorectal tissue’s zinc concentration was significantly lower in CRC patients compared to healthy control cohorts. There was no significant difference on the measured elements in samples from CRC patients with MMR⁻ compared to CRC patients with MMR⁺. Receiver operating characteristic analysis revealed a correlation of blood iron, zinc, copper, and phosphorus to CRC, and inappropriately low levels of blood and colorectal selenium correlated with exacerbated metastasis. Altered levels of selenium, iron, copper, zinc, and phosphorus in vivo may impact the pathogenesis and detection of CRC, and their diagnostic/therapeutic potential in CRC would be revealing.