Inulin significantly improves serum magnesium levels in proton pump inhibitor-induced hypomagnesaemia.

BACKGROUND: Proton pump inhibitors (PPI) are among the most widely prescribed drugs to treat gastric acid-related disorders. PPI-induced hypomagnesaemia, a defect in intestinal absorption of Mg(2+) , can be a severe side effect of chronic PPI use. AIM: To restore serum Mg(2+) concentrations in PPI-induced hypomagnesaemia patients by dietary supplementation with inulin fibres. METHODS: Eleven patients with PPI-induced hypomagnesaemia and 10 controls were treated with inulin (20 g/day). Each trial consisted of two cycles of 14-day inulin treatment followed by a washout period of 14 days. Patients continued to use their PPI. Serum Mg(2+) levels served as the primary endpoint. RESULTS: Inulin significantly enhanced serum Mg(2+) levels from 0.60 to 0.68 mmol/L in PPI-induced hypomagnesaemia patients, and from 0.84 to 0.93 mmol/L in controls. As a consequence 24 h urinary Mg(2+) excretion was significantly increased in patients with PPI-induced hypomagnesaemia (0.3-2.2 mmol/day). Symptoms related to hypomagnesaemia, including muscle cramps and paraesthesia, were reduced during intervention with inulin. CONCLUSION: Inulin increases serum Mg(2+) concentrations under PPI maintenance in patients with PPI-induced hypomagnesaemia.

Immunocytochemical localisation of actin and profilin in the generative cell of angiosperm pollen: TEM studies on high-pressure frozen and freeze-substituted Ledebouria socialis Roth (Hyacinthaceae).

Actin was demonstrated for the first time at the EM level in the generative cell of mature angiosperm pollen by using immuno-gold labelling of high-pressure frozen and freeze-substituted Ledebouria socialis Roth anthers. In addition, profilin, an actin-monomer binding protein, is shown to coexist in the generative cell. We attribute the detection of actin and profilin to the applied cryomethods which yield a much better preservation of ultrastructure and antigenicity of delicate cytoskeletal constituents than conventional fixation techniques. Actin labelling was observed within the cytoplasm of the generative cell and became especially clear in close vicinity to microtubular bundles. Filamentous structures congruent with the actin labelling patterns do occur, but are not a frequent feature. Profilin was localised throughout the cytoplasm.

High-pressure freeze fixation reveals novel features during ontogenesis of the vegetative cell in Ledebouria pollen: an ultrastructural and cytochemical study.

The ultrastructure of the vegetative cell in the pollen of Ledebouria socialis Roth (Hyacinthaceae) was investigated from microspore mitosis to anthesis. As a result of the good preservation quality achieved with high-pressure freeze fixation and freeze substitution, novel structural features were observed. Extensive endomembrane compartments emerging at the onset of lipid and starch mobilization, were identified as protein bodies by using video-enhanced contrast light microscopy. Thus, proteins, apart from starch and lipids, represent a third class of important intermediary storage substances in developing pollen. The close spatial relationship between protein bodies, endoplasmic reticulum (ER), and storage lipids suggest that protein bodies and ER contribute to lipid digestion. Immediately prior to anthesis the protein bodies become transformed into unspecialized vacuoles as a result of the gradual dissolution of their contents; the formation of the protein bodies remains still to be elucidated. The ER proliferates extensively during pollen ontogenesis, thereby changing its ultrastructure and spatial organization. Microfilaments were detected during all developmental stages, in particular microtubule-associated single microfilaments. The microfilaments are likely to be composed of actin as shown by immunogold labeling.

A simple and inexpensive device for freeze substitution at 183 K/-90 C.

The freeze substitution device described here consists of commonly available materials, is easy to construct and to handle and provides maximal working safety. An adequate mass of copper and/or brass, serving as holder for 16 cryovials, is chilled to liquid nitrogen temperature. The vial holder is placed in a precooled thermos flask filled with ethanol and stored in an ultrafreezer at 193 K/-90 C. This ensures that the vial holder maintains temperatures of about 183 K/-90 C for more than 12 hr to minimize the risk of ice recrystallization.

Interplay between extracellular -SH groups and Ca2+ in their mitogenic action on murine lymphocytes: the role of SiO2.

Murine spleen lymphocytes, cultured under serum-free conditions and stimulated with concanavalin A (Con A), showed an increased demand for supplemental concentrations of Ca2+ when 2-mercaptoethanol (2-ME) or L-cysteine were also present in the culture medium. The requirement for additional Ca2+ ions was particularly evident at high cell concentrations. The addition of SiO2 (Aerosil 200), in concentrations depending on the original level of Ca2+ in the culture medium, could substitute for the increased demand on calcium ions. This dependency of SiO2 effects on calcium levels in the medium was also evident when supraoptimal, i.e. inhibitory concentrations of silica were tested. Results of experiments with 45Ca suggest that silica particles may act as intercellular carriers of calcium. In contrast to spleen lymphocytes, Con A-stimulated thymus cells exhibited neither a need for an increase in the concentration of Ca2+ nor a dependency on the presence of 2-ME in the medium.