Effect of aluminum chloride on mitogenesis, mitosis, and cell cycle in human short-term whole blood cultures: lower concentrations enhance mitosis

Cytotoxicity and genotoxicity effects of water boiled in aluminum vessels on Allium cepa root tip cells

Cookwares made from aluminum (Al) are supposed to be a potential source of Al contamination of food. In this study, the cytotoxicity and genotoxicity effects of water boiled in aluminum cookwares on the dividing cells of onion root tip were examined using Allium cepa assay. Three used aluminum cookwares from different sources were selected. Distilled water was gently boiled in each pot and then used for growing onions. The cells of root tip were analyzed for mitotic and phase indexes as well as aberrations appeared in the interphase and mitotic phase. One way analysis of variance and post-hoc Tukey HSD test were applied for comparison between experimental groups. The results showed that the mitotic index in one of the treated groups increased significantly compared to the control. Also the frequency of prophase in two of treated groups increased significantly compared to that of the control. There was a borderline significant increase in the frequency average of total aberrations from three treated groups compared to that of the control (p value = 0.063). Also, a significant increase was observed in the frequency average of disturbed mitosis from three treated groups compared to that of the control (p value = 0.04). The findings of this preliminary study supported a possible health hazard of aluminum cookwares. Further investigation with larger sample and food with various compositions is needed to reach a full conclusion about the health effect of aluminum cookwares.

Impaired Perforin-Dependent NK Cell Cytotoxicity and Proliferative Activity of Peripheral Blood T Cells is Associated with Metastatic Melanoma

Aims and Background

Patients with metastatic melanoma often have defects in the percentage and function of peripheral blood NK cells, which are involved in the non-specific innate antitumor immune response, and T cells, which participate in the specific acquired antitumor immune response. The aim of this study was to investigate in more detail not only the percentage but also the activation status and function of NK and T cells in patients with metastatic melanoma prior to therapy.

Methods

The percentage of peripheral blood CD56+ NK cells, CD3+ T cells and their CD4+ and CD8+ subsets, as well as the expression of the activation antigens CD69, CD38 and HLA-DR were analyzed by flow cytometry. The functional capacity of NK cells was evaluated by the 51-chromium release cytotoxicity assay, while the proliferative activity of T cells was estimated by the lymphocyte transformation test to mitogen phytohemagglutinin.

Results

The results obtained in this study have revealed a new aspect of NK and T cell dysfunction that is not, as commonly reported, associated with a decrease in their percentage. Moreover, a significant number of the investigated patients had a higher percentage of NK cells that did not lead to improved NK ceil cytotoxicity as a result of the detected defect in the NK cell perforin-mediated cytotoxic mechanism of tumor cell lysis. The impaired proliferative response of T cells was associated with a decreased expression of the activation antigen HLA-DR.

Conclusion

The novel finding in this study of melanoma patients with metastatic disease is the impaired perforin-depen-dent NK cell cytotoxic mechanism, which was recently shown to be primarily responsible for preventing metastasis. Another interesting finding was the generally hyporeactive status of T cells, possibly resulting from persistent antigenic stimulation. The observed dysfunction of NK and T cells in patients with metastatic melanoma prior to therapy point to the need to supplement chemotherapy with appropriate immunotherapeutic agents in order to overcome the immunosuppression associated with advanced malignancy.

Optimal dose of zinc supplementation for preventing aluminum-induced neurotoxicity in rats

Zinc supplementation can help maintain learning and memory function in rodents. In this study, we hypothesized that zinc supplementation could antagonize the neurotoxicity induced by aluminum in rats. Animals were fed a diet containing different doses of zinc (50, 100, 200 mg/kg) for 9 weeks, and orally administered aluminum chloride (300 mg/kg daily) from the third week for 7 consecutive weeks. Open-field behavioral test results showed that the number of rearings in the group given the 100 mg/kg zinc supplement was significantly increased compared with the group given the 50 mg/kg zinc supplement. Malondialdehyde content in the cerebrum was significantly decreased, while dopamine and 5-hydroxytryptamine levels were increased in the groups given the diet supplemented with 100 and 200 mg/kg zinc, compared with the group given the diet supplemented with 50 mg/kg zinc. The acetylcholinesterase activity in the cerebrum was significantly decreased in the group given the 100 mg/kg zinc supplement. Hematoxylin-eosin staining revealed evident pathological damage in the hippocampus of rats in the group given the diet supplemented with 50 mg/kg zinc, but the damage was attenuated in the groups given the diet supplemented with 100 and 200 mg/kg zinc. Our findings suggest that zinc is a potential neuroprotective agent against aluminum-induced neurotoxicity in rats, and the optimal dosages are 100 and 200 mg/kg.

Programmed cell death-involved aluminum toxicity in yeast alleviated by antiapoptotic members with decreased calcium signals

The molecular mechanisms of aluminum (Al) toxicity and tolerance in plants have been the focus of ongoing research in the area of stress phytophysiology. Recent studies have described Al-induced apoptosis-like cell death in plant and animal cells. In this study, we show that yeast (Saccharomyces cerevisiae) exposed to low effective concentrations of Al for short times undergoes enhanced cell division in a manner that is dose and cell density dependent. At higher concentrations of Al or longer exposure times, Al induces cell death and growth inhibition. Several apoptotic features appear during Al treatment, including cell shrinkage, vacuolation, chromatin marginalization, nuclear fragmentation, DNA degradation, and DNA strand breaks, as well as concomitant cell aggregation. Yeast strains expressing Ced-9, Bcl-2, and PpBI-1 (a plant Bax inhibitor-1 isolated from Phyllostachys praecox), respectively, display more resistance to Al toxicity compared with control cells. Data from flow cytometric studies show these three antiapoptotic members do not affect reactive oxygen species levels, but decrease calcium ion (Ca(2+)) signals in response to Al stress, although both intracellular reactive oxygen species and Ca(2+) levels were increased. The data presented suggest that manipulation of the negative regulation process of programmed cell death may provide a novel mechanism for conferring Al tolerance.

The effect of colcemid and aluminum on the ultrastructure of human metaphase chromosomes

Recently, we have reported new basic information on the ultrastructure of human metaphase chromosomes using both scanning and transmission electron microscopy. This includes the observation of a bipartite chromatid structure (BCS) for some metaphase chromatids, a "zipper-like" configuration (ZC) between chromatids that likely resulted from chromatin coiling, and a "brush-like" border (BB) that was observed primarily on chromosomes that were not exposed to colcemid. Now we have examined the effects of colcemid and several metals on the occurrence of the BCS, the ZC, and the BB. Although we do not as yet know the function of the zipper-like and bipartite chromatid configurations, we have found that colcemid clearly caused a significant increase in the occurrence of chromosomes with a BCS or ZC. We also have confirmed our original observation of increased occurrence of the BB on chromosomes not exposed to colcemid and finally, have shown that aluminum and other metals had some effect on the frequencies of the BCS, the ZC, and the BB with and without exposure to colcemid.

Cellular actions of Al at low (1.25 microM) concentrations in primary oligodendrocyte culture

At a physiologically relevant concentration (1.25 microM), aluminum had an activating effect on oligodendrocyte cell cultures, similar to that previously reported for other cell types. G protein-linked signal transduction was stimulated as indicated by enhanced production of IP3, and protein synthesis was increased. At this concentration Al did not promote cell damage but did enhance oxidative effects initiated by reactive oxygen species. Both AlCl(3) and Al transferrin (AlTf) had similar actions at equimolar concentrations. In vivo, physiological Al ion may act by common cellular pathways in diverse cell types. These effects may be relevant to Al toxicological, pharmacological (immunoadjuvant), and physiological effects.

Human chromatid ultrastructure: new observations with scanning and transmission electron microscopy

Two new observations have been made on human chromatid/chromosome ultrastructure using both scanning and transmission electron microscopy (SEM, TEM). A bipartite, apparently half-chromatid-like structure was observed in whole human chromosomes studied with SEM and in longitudinally sectioned chromosomes analyzed with TEM. In addition, we also observed a zipper-like configuration as the parallel sister chromatids separated likely due to the supercoiled structure of the chromosome and chromatid. It is possible that either or both of these new observations resulted from our (improved) method of preparing the chromosomes for SEM and TEM.

Does aluminium stimulate the immune system in male rats after oral exposure?

The influence of oral aluminium exposure on the immune system was studied in rats. Male rats were exposed to soluble and labile Al in acidic drinking water (0-500 mg Al/l) for 7-9 weeks. The concentration of Al in femur bone was higher in rats exposed to 50 and 500 mg Al/l (mean concentration 277 and 599 ng Al/g) than in control rats (150 ng Al/g). The Al concentration in blood plasma could only be quantified in the 500 mg/l group (mean 2.7 ng/ml), whereas the concentrations in the control and 50 mg/l groups were low (< 2 ng Al/ml). Exposure of 4-13-weeks-old rats to the highest Al concentration caused an increased number of splenocytes, whereas exposure of 9-16-weeks-old rats to 500 mg Al/l caused an increased number of thymocytes. Moreover, the proliferative response of splenocytes to the mitogen Con A (2 micrograms/ml) was increased by exposure of the 9-16-weeks-old rats to 500 mg Al/l as compared with the controls. The results indicate that oral Al exposure caused a slight stimulation of some immune functions in the rat at Al plasma concentrations normally found in the human population (< 10 ng Al/ml).

Mechanisms of uptake of gallium by human neuroblastoma cells and effects of gallium and aluminum on cell growth, lysosomal protease, and choline acetyl transferase activity

We have studied the uptake and removal of gallium, used as an analogue of aluminum, and the effects of aluminum itself on cultured human neuroblastoma cells treated with soluble metal complexes. The prohibitively high cost of measurement of the only available radioisotope of aluminum (26Al) precluded its usage, and so we considered that gallium, which is chemically extremely similar, would be the most suitable model. Gallium has been used thus in a number of previous biological studies and has been found to behave like aluminum in many respects. We have previously shown that Al-EDTA treatment results in uptake of aluminum and expression of hyperphosphorylated tau, a key component of Alzheimer's disease paired helical filaments. Here we demonstrate that gallium uptake can occur by two separate methods, both leading to physiologically relevant intracellular metal concentrations. Uptake from medium containing bovine transferrin occurred mainly by pinocytosis, but in the presence of human transferrin (hTf), uptake by transferrin-mediated endocytosis occurred also, despite a very low level of hTf saturation, indicating that Tf-mediated uptake is a very effective method of Ga internalization. The intracellular gallium is relatively stable, though partially removable by (1 mM) EDTA, desferrioxamine, or 1,2-dimethyl-3-hydroxypyrid-4-one. Aluminum and gallium treatment were found to increase the overall activity of lysosomal proteases, enzymes implicated in amyloid precursor protein cleavage. No effects were detected on choline acetyl transferase activity, cell growth, or tritiated thymidine incorporation or on the structure of the cells, as judged by light or electron microscopy.

Identification of a candidate human spectrin Src homology 3 domain-binding protein suggests a general mechanism of association of tyrosine kinases with the spectrin-based membrane skeleton

Spectrin is a widely expressed protein with specific isoforms found in erythroid and nonerythroid cells. Spectrin contains an Src homology 3 (SH3) domain of unknown function. A cDNA encoding a candidate spectrin SH3 domain-binding protein was identified by interaction screening of a human brain expression library using the human erythroid spectrin (alphaI) SH3 domain as a bait. Five isoforms of the alphaI SH3 domain-binding protein mRNA were identified in human brain. Mapping of SH3 binding regions revealed the presence of two alphaI SH3 domain binding regions and one Abl-SH3 domain binding region. The gene encoding the candidate spectrin SH3 domain-binding protein has been located to human chromosome 10p11.2 --> p12. The gene belongs to a recently identified family of tyrosine kinase-binding proteins, and one of its isoforms is identical to e3B1, an eps8-binding protein (Biesova, Z., Piccoli, C., and Wong, W. T. (1997)Oncogene 14, 233-241). Overexpression of the green fluorescent protein fusion of the SH3 domain-binding protein in NIH3T3 cells resulted in cytoplasmic punctate fluorescence characteristic of the reticulovesicular system. This fluorescence pattern was similar to that obtained with the anti-human erythroid spectrin alphaI SigmaI/betaI SigmaI antibody in untransfected NIH3T3 cells; in addition, the anti-alphaI SigmaI/betaI SigmaI antibody also stained Golgi apparatus. Immunofluorescence obtained using antibodies against alphaI SigmaI/++betaI SigmaI spectrin and Abl tyrosine kinase but not against alphaII/betaII spectrin colocalized with the overexpressed green fluorescent protein-SH3-binding protein. Based on the conservation of the spectrin SH3 binding site within members of this protein family and published interactions, a general mechanism of interactions of tyrosine kinases with the spectrin-based membrane skeleton is proposed.