The Quantitative Glucose and Mineral Nutrient Requirements of Mouse LS (Suspension) Cells in Chemically Defined Medium

Low gut microbiota diversity and dietary magnesium intake are associated with the development of PPI-induced hypomagnesemia

Proton pump inhibitors (PPIs) are used by millions of patients for the treatment of stomach acid-reflux diseases. Although PPIs are generally considered safe, about 13% of the users develop hypomagnesemia. Despite rising attention for this issue, the underlying mechanism is still unknown. Here, we examine whether the gut microbiome is involved in the development of PPI-induced hypomagnesemia in wild-type C57BL/6J mice. After 4 wk of treatment under normal or low dietary Mg²⁺ availability, omeprazole significantly reduced serum Mg²⁺ levels only in mice on a low-Mg²⁺ diet without affecting the mRNA expression of colonic or renal Mg²⁺ transporters. Overall, 16S rRNA gene sequencing revealed a lower gut microbial diversity in omeprazole-treated mice. Omeprazole induced a shift in microbial composition, which was associated with a 3- and 2-fold increase in the abundance of Lactobacillus and Bifidobacterium, respectively. To examine the metabolic consequences of these microbial alterations, the colonic composition of organic acids was evaluated. Low dietary Mg²⁺ intake, independent of omeprazole treatment, resulted in a 10-fold increase in formate levels. Together, these results imply that both omeprazole treatment and low dietary Mg²⁺ intake disturb the gut internal milieu and may pose a risk for the malabsorption of Mg²⁺ in the colon.-Gommers, L. M. M., Ederveen, T. H. A., van der Wijst, J., Overmars-Bos, C., Kortman, G. A. M., Boekhorst, J., Bindels, R. J. M., de Baaij, J. H. F., Hoenderop, J. G. J. Low gut microbiota diversity and dietary magnesium intake are associated with the development of PPI-induced hypomagnesemia.

Renal phospholipidosis and impaired magnesium handling in high-fat-diet-fed mice

Hypomagnesemia (blood Mg²⁺ concentration <0.7 mM) is a common electrolyte disorder in patients with type 2 diabetes (T2D), but the etiology remains largely unknown. In patients with T2D, reduced blood Mg²⁺ levels are associated with an increased decline in renal function, independent of glycemic control and hypertension. To study the underlying mechanism of this phenomenon, we investigated the renal effects of hypomagnesemia in high-fat-diet (HFD)-fed mice. In mice fed a low dietary Mg²⁺, the HFD resulted in severe hypomagnesemia within 4 wk. Renal or intestinal Mg²⁺ wasting was not observed after 16 wk on the diets. Despite the absence of urinary or fecal Mg²⁺ loss, the HFD induced a reduction in the mRNA expression transient receptor potential melastatin type 6 in both the kidney and colon. mRNA expression of distal convoluted tubule (DCT)-specific genes was down-regulated by the LowMg-HFD, indicating atrophy of the DCT. The low dietary Mg²⁺ resulted in severe HFD-induced proximal tubule phospholipidosis, which was absent in mice on a NormalMg-HFD. This was accompanied by albuminuria, moderate renal damage, and alterations in renal energy metabolism, including enhanced gluconeogenesis and cholesterol synthesis. In conclusion, this study shows that hypomagnesemia is a consequence of diet-induced obesity and insulin resistance. Moreover, hypomagnesemia induces major structural changes in the diabetic kidney, including proximal tubular phospholipidosis, providing a novel mechanism for the increased renal decline in patients with hypomagnesemic T2D.-Kurstjens, S., Smeets, B., Overmars-Bos, C., Dijkman, H. B., den Braanker, D. J. W., de Bel, T., Bindels, R. J. M., Tack, C. J. J., Hoenderop, J. G. J., de Baaij, J. H. F. Renal phospholipidosis and impaired magnesium handling in high-fat-diet-fed mice.

Nuclear staining and culture requirements for in vitro maturation of domestic bitch oocytes

Oocyte nuclear staining and culture requirements for in vitro maturation (IVM) in the bitch have yet to be fully investigated. In the first part of this study we investigated 7 methods for labeling nuclear material (573 oocytes). The most favorable method involved fixation plus aceto-orcein staining and light microscopy. The influence of serum supplementation of the culture medium for IVM was then investigated (1292 oocytes). Culture was performed in media supplemented with no serum or with 5, 10 and 20% fetal calf serum (FCS) and 0.3 or 4% bovine serum albumin (BSA). Identifiable nuclear material was either a germinal vesicle (GV) or GV breakdown (GVBD). After 48 h in medium plus 0, 5, 10 or 20% FCS and 0.3 or 4% BSA, the percentage of oocytes matured to GVBD was 13, 9, 15, 23, 36 and 40%, and the percentage matured to metaphase I/anaphase I/metaphase II was 4, 12, 24, 14, 36 and 13%, respectively. After 96 h, maturation to GVBD was 31, 14, 21, 11, 50 and 38%, and to metaphase I/anaphase I/metaphase II it was 6, 5, 3, 19, 15 and 9%, respectively. Within the limits of this study, BSA or high concentrations of FCS appear to be optimal for bitch oocyte maturation in vitro.

The roles of magnesium in biotechnology

This review highlights the important roles played by magnesium in the growth and metabolic functions of microbial and animal cells, and therefore assigns a key role for magnesium ions in biotechnology. The fundamental biochemical and physiological actions of magnesium as a regulatory cation are outlined. Such actions are deemed to be relevant in an applied sense, because Mg2+ availability in cell culture and fermentation media can dramatically influence growth and metabolism of cells. Manipulation of extracellular and intracellular magnesium ions can thus be envisaged as a relatively simplistic, but nevertheless versatile, means of physiological cell engineering. In addition, biological antagonism between calcium and magnesium at the molecular level may have profound consequences for the optimization of biotechnological processes that exploit cells. In fermentation, for example, it is argued that the efficiency of microbial conversion of substrate to product may be improved by altering Mg:Ca concentration ratios in industrial feedstocks in a way that makes more magnesium available to the cells. With particular respect to yeast-based biotechnologies, magnesium availability is seen as being crucially important in governing central pathways of carbohydrate catabolism, especially ethanolic fermentation. It is proposed that such influences of magnesium ions are expressed at the combined levels of key enzyme activation and cell membrane stabilization. The former ensures optimum flow of substrate to ethanol and the latter acts to protect yeasts from physical and chemical stress.

Biological, physical, and electrical parameters for in vitro studies with ELF magnetic and electric fields: a primer

This paper presents material which is intended to assist researchers in identifying and controlling a range of biological, electrical, and other physical parameters that can affect the outcome of in vitro studies with extremely low frequency (ELF) magnetic and electric fields. Brief descriptions of power line magnetic and electric fields are provided and methods for the generation of 60 Hz as well as other ELF fields in the laboratory are surveyed. Methods for calculating and measuring exposure parameters in culture medium are also described. Relating in vitro and internal in vivo exposure conditions across different animal species is discussed to aid researchers in selecting levels of field exposure. The text is purposely elementary, and sometimes brief, with references provided to aid the interested reader in obtaining a fuller understanding of the many topics. Because the range of experimental parameters that can influence the outcome of in vitro studies with ELF fields is so broad, a multidisciplinary approach is normally required to carry out the research.