In vitro studies on methyl mercury distribution in human blood

Studies comparing the methyl mercury (mHg) content of maternal and newborn blood have shown increased levels in the newborn. This has been attributed to facilitated transplacental diffusion because of high fetal hematocrit (Hct). This study shows the converse, that the diffusion of mHg diminishes progressively with increasing Hct. The diffusion of m203Hg across a Millipore membrane (0.45 microns) separating compartments A and B of a diffusion cell was studied. When both compartments contained saline or plasma alone, equilibration from A to B occurred in 5 h. Introduction of human red blood cells (RBC) in saline (Hct 20%) into B resulted in a twofold increase in diffusion of mHg when compared to saline alone. Increasing Hct in saline in compartment B resulted in a progressive decrease in diffusion (r = -0.95, P less than 0.001). The presence of RBC in plasma (Hct 20%) in B resulted in a 70% decrease in diffusion; with increasing Hct, diffusion was further reduced (r = -0.95, P less than 0.001). Direct addition of mHg to RBC in saline resulted in 98% RBC uptake. Increasing concentrations of plasma (at a constant Hct) resulted in a progressive decrease in RBC uptake. In undiluted plasma at Hct 14%, RBC uptake of mHg was 35%. Plasma electrophoresis showed that much of the mHg was associated with a high-molecular-weight lipoprotein fraction. Plasma components appear to be important in the distribution of mHg in blood, and may be a factor in the relatively higher blood levels in the fetus.     

Evaluation of GABA Production and Probiotic Activities of Enterococcus faecium BS5

Probiotics and Antimicrobial Proteins - Gamma-aminobutyric acid (GABA) is a principal inhibitory neurotransmitter in the central nervous system and is produced by irreversible decarboxylation of...     

The nesprins are giant actin-binding proteins,orthologous to Drosophila melanogaster muscle protein MSP-300

Nesprin-1 and nesprin-2 (also known as Syne-1 and Syne-2,) are large ( approximately 3300-residue) vertebrate proteins associated with emerin and lamin A at the nuclear envelope of muscle cells and other cell types. We show that the previously described nesprins are short isoforms of giant proteins comprising an actin-binding amino-terminus connected to a carboxy-terminal klarsicht-related transmembrane domain by a massive ( approximately 6000-8000 amino acid) spectrin-like rod domain, making full-length nesprin-1, at one megadalton, the largest non-titin protein hitherto described in humans. We find that MSP-300, a 7000-residue Drosophila melanogaster protein whose disruption results in defects of muscle development, corresponds to the N-terminal two-thirds of the Drosophila nesprin ortholog. A nesprin-like protein is also encoded by the nematode genome. Moreover, we demonstrate that the larger isoforms of nesprin-1, like MSP-300, are localized to the sarcomeric Z-line of both skeletal and cardiac muscle. The recognition that a characteristic muscle-specific mutant phenotype in the fly results from a disruption of its nesprin ortholog reinforces the candidacy of the human proteins for involvement in genetic diseases of skeletal and cardiac muscle.     

Role of cyclin G-associated kinase in uncoating clathrin-coated vesicles from non-neuronal cells

Auxilin is a brain-specific DnaJ homolog that is required for Hsc70 to dissociate clathrin from bovine brain clathrin-coated vesicles. However, Hsc70 is also involved in uncoating clathrin-coated vesicles formed at the plasma membrane of non-neuronal cells suggesting that an auxilin homolog may be required for uncoating in these cells. One candidate is cyclin G-associated kinase (GAK), a 150-kDa protein expressed ubiquitously in various tissues. GAK has a C-terminal domain with high sequence similarity to auxilin; like auxilin this C-terminal domain consists of three subdomains, an N-terminal tensin-like domain, a clathrin-binding domain, and a C-terminal J-domain. Western blot analysis shows that GAK is present in rat liver, bovine testes, and bovine brain clathrin-coated vesicles. More importantly, liver clathrin-coated vesicles, which contain GAK but not auxilin, are uncoated by Hsc70, suggesting that GAK acts as an auxilin homolog in non-neuronal cells. In support of this view, the clathrin-binding domain of GAK alone induces clathrin polymerization into baskets and the combined clathrin-binding domain and J-domain of GAK supports uncoating of AP180-clathrin baskets by Hsc70 at pH 7 and induces Hsc70 binding to clathrin baskets at pH 6. Immunolocalization studies suggest that GAK is a cytosolic protein that is concentrated in the perinuclear region; it appears to be highly associated with the trans-Golgi where the budding of clathrin-coated vesicles occurs. We propose that GAK is a required cofactor for the uncoating of clathrin-coated vesicles by Hsc70 in non-neuronal cells.     

Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds

Monolayer formation of SaOS‐2 (human osteoblast‐like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non‐toxicity and the flat spreading with monolayer formation of the SaOs‐2 on VACNT scaffolds surface indicate that they can be used for biomedical applications.     

Effect of the petite mutation on maltose and alpha-methylgucoside fermentation inSaccharomyces cerevisiae.

Summary Several hundred petite mutants were isolated from yeast strains of different genotype to examine the effect of the petite mutation on maltose and alpha-methylglucoside fermentation. In most cases petite mutants isolated retain the ability to ferment maltose and alpha-methylglucoside, although at a slower rate. In one strain (1403-7A), however, the ability to ferment alpha-methylglucoside is completely lost in all petite mutants isolated from this strain. It is suggested that mitochondrial factors may be involved in the utilization of alpha-methylglucoside in strain 1403-7A.     

Immunophenotyping of human HT29 colon cancer cell primary tumours and their metastases in severe combined immunodeficient mice

The immunophenotype of HT29 human colon cancer cells implanted into severe combined immunodeficient mice was assessed in primary tumours and their metastases in the lungs using an indirect immunohistochemical method. After primary tumours were surgically removed, the metastases were given time to develop, thus paralleling the clinical situation. While vimentin was negative in both primary and secondary tumours, E-cadherin was present as membrane-bound labelling in the primary tumours only. Whereas the markers p53, MIB1, PCNA and CEA were consistently positive in both primary and metastatic tumours, CD44 variant 6 and CA125 were negative in metastases but positive in the primary tumours. There was a significant increase in the percentage of cells labelled for p53 in the primary tumours compared with the metastases. For the proliferation markers, there was no significant difference in labelling between primary tumours and metastases for MIB1. Of the cytokeratins examined, CK 20 gave the strongest and most consistent reaction in both primary and secondary tumours. The results indicate that, for certain immunohistochemical markers, results are the same in both primary tumours and metastases. Hence, in these cases, antigens that are expressed on the primary tumour as well as on the metastases can serve as target molecules for immunologically based forms of treatment of metastases. This revised version was published online in November 2006 with corrections to the Cover Date.