Involvement of IL-10 and Bcl-2 in resistance against an asbestos-induced apoptosis of T cells

To analyze the possibility that immunological alteration in asbestos-related diseases (ARDs) such as asbestosis (ASB) and malignant mesothelioma (MM) may affect the progression of cancers, a human adult T cell leukemia virus-immortalized T cell line (MT-2Org) was continuously exposed to 10 μg/ml of chrysotile-B (CB), an asbestos. After at least 8 months of exposure, the rate of apoptosis in the cells became very low and the resultant subline was designated MT-2Rst. The MT-2Rst cells were characterized by (i) enhanced expression of bcl-2, with regain of apoptosis-sensitivity by reduction of bcl-2 by siRNA, (ii) excess IL-10 secretion and expression, and (iii) activation of STAT3 that was inhibited by PP2, a specific inhibitor of Src family kinases. These results suggested that the contact between cells and asbestos may affect the human immune system and trigger a cascade of biological events such as activation of Src family kinases, enhancement of IL-10 expression, STAT3 activation and Bcl-2 overexpression. This speculation was partially confirmed by the detection of elevated bcl-2 expression levels in CD4 + peripheral blood T cells from patients with MM compared with those from patients with ASB or healthy donors. Further studies will be required to verify the role of T cells with enhanced bcl-2 expression in tumor progression induced by asbestos exposure.     

Protective role of metallothionein against copper depletion

Copper (Cu) is one of the essential metals and its homeostasis is strictly regulated. Metallothionein (MT) is induced by excess Cu to mask the Cu toxicity. Although the role of MT in Cu toxicity has been explained in terms of Cu sequestration, its role under Cu-deficient conditions is not known. This study was carried out to determine the role of MT in Cu depletion by a Cu(I)-specific chelator, bathocuproine sulfonate (BCS), in cultured cells established from MT-knockout mouse and its wild type. Viability was decreased more severely in MT-null cells than in wild-type cells by BCS treatment. The expression levels of both MT isoforms were increased by BCS treatment in wild-type cells. Thus, MT was shown to be induced under Cu-deficient conditions to maintain the activities of intracellular cuproenzymes such as cytochrome c oxidase and Cu,zinc-superoxide dismutase.     

Multipotent cells from the human third molar: feasibility of cell-based therapy for liver disease

Abstract Adult stem cells have been reported to exist in various tissues. The isolation of high-quality human stem cells that can be used for regeneration of fatal deseases from accessible resources is an important advance in stem cell research. In the present study, we identified a novel stem cell, which we named tooth germ progenitor cells (TGPCs), from discarded third molar, commonly called as wisdom teeth. We demonstrated the characterization and distinctiveness of the TGPCs, and found that TGPCs showed high proliferation activity and capability to differentiate in vitro into cells of three germ layers including osteoblasts, neural cells, and hepatocytes. TGPCs were examined by the transplantation into a carbon tetrachloride (CCl₄)-treated liver injured rat to determine whether this novel cell source might be useful for cell-based therapy to treat liver diseases. The successful engraftment of the TGPCs was demonstrated by PKH26 fluorescence in the recipient's rat as to liver at 4 weeks after transplantation. The TGPCs prevented the progression of liver fibrosis in the liver of CCl₄-treated rats and contributed to the restoration of liver function, as assessed by the measurement of hepatic serum markers aspartate aminotransferase and alanine aminotransferase. Furthermore, the liver functions, observed by the levels of serum bilirubin and albumin, appeared to be improved following transplantation of TGPCs. These findings suggest that multipotent TGPCs are one of the candidates for cell-based therapy to treat liver diseases and offer unprecedented opportunities for developing therapies in treating tissue repair and regeneration.     

Embryonic lethality resulting from disruption of both N-myc alleles in mouse zygotes

The N-myc gene is considered to play a major regulatory role in embryogenesis of the mouse because of its high expression in the organogenesis period and its encoding of nuclear proteins with DNA binding motifs. To elucidate the putative regulatory function of N-myc in embryogenesis, we undertook to inactivate this gene in ES cells. The N-myc alleles were disrupted in ES cells, line E14, by means of homologous recombination of targeting vectors that carry neomycin or hygromycin resistant genes. Homologous recombinants were obtained at the frequency of one in 6 x 10(5) electroporated cells. The inactivated N-myc alleles were transmitted through mouse germ lines. Crosses of heterozygous mice resulted in production of wild-type, heterozygous, and N-myc-null pups and fetuses at a ratio of 1:2:0, indicating embryonic lethality of the homozygotes. ES cells totally deficient in N-myc expression were also obtained by consecutive gene disruption with the use of the targeting vectors, demonstrating the non-essentiality of N-myc expression in the stem-cell state. N-myc-null ES cells offer a valuable tool in chimera analysis to elucidate the requirement for N-myc function in embryogenesis.     

D-lactate concentrations in blood, urine and sweat before and after exercise.

The purpose of this study was to investigate changes in the concentrations of D-lactate, L-lactate, pyruvate and methylglyoxal (MG) in body fluids after exercise. Eight untrained male students and five male students who were boat club members engaged in the exercise. Each subject performed runs of short and long duration. Compared to pre-exercise values plasma concentrations of D-lactate, L-lactate and pyruvate increased after running; in trained men by 3.6, 5.0, 3.4 times after short runs and by 1.5, 4.6, 2.0 times after long runs, and in untrained men by 3.0, 12.0, 1.6 times after short runs and 2.5, 5.6, 1.6 times after long runs, respectively. In all cases, the increase of L-lactate was always higher than that of D-lactate after running. The MG contents in red blood cells decreased markedly after running, especially in the untrained students. After short runs the MG concentration had decreased to 13% in the untrained men and 30% in the trained men, and after long runs the concentration had decreased to 41% in the untrained and 60% in the trained men. The MG in plasma and red blood cells appeared to have been utilized during relatively anaerobic exercise, especially by the untrained subjects. The D-lactate and related substances were also determined in urine, but the concentration of these substances showed no relationship to exercise. The D-lactate concentration in sweat samples tripled after short periods of running but the relative concentration to sodium ion concentration was not altered.(ABSTRACT TRUNCATED AT 250 WORDS)     

The bacterial cell division protein FtsZ forms rings in swarmer cells of Proteus mirabilis

Bacterial FtsZ assembles and constricts after chromosomal segregation in the course of cell division. Here we examined the localization of FtsZ in multinucleated swarmer cells of Proteus mirabilis by immunostaining. FtsZ was found to localize to the point of karyomitosis in swarmer cells of P. mirabilis, which is equivalent to filamentous mutants of Escherichia coli defective in the ftsI or ftsQ genes that are involved in later steps of cell division. Thus our findings suggest that the appearance of swarmer cells results from cellular functions immediately after FtsZ assembly.     

Activation of caspase 3 in HepG2 cells by elaidic acid (t18:1)

In order to examine the effects of trans-unsaturated fatty acids (TFAs) on HepG2 cells, cells were grown in serum-free media supplemented with elaidic acid (t18:1); t18:1 is the trans-isomer of oleic acid and is the major component of TFAs in foods. Both t18:1 and palmitic acids (16:0) at concentrations higher than 100 microM inhibited growth and decreased the rate of protein synthesis. The presence of phosphatidylserine in the outer leaflet of the lipid bilayer, indicative of apoptosis, occurred 1 h after the addition of both t18:1 and 16:0 to the media. Caspase 3 was found to be activated by these fatty acids: caspase 8 was activated by 16:0 and only moderately by t18:1. Activation of caspase 3 by these fatty acids was fully inhibited by a caspase 8 inhibitor. However, growth inhibition by t18:1 was partially prevented by the caspase 8 inhibitor. These results suggest that cell death caused by t18:1 may proceed by both caspase-dependent and -independent pathways.     

Easy assessment of ES cell clone potency for chimeric development and germ-line competency by an optimized aggregation method.

Production of germ-line competent chimeric mice from embryonic stem (ES) cells is an inevitable step in establishing gene-manipulated mouse lineages. A common method used for creating chimeric mice is the injection of ES cells into the blastocoelic cavity (blastocyst injection). The aggregation method is an alternative way to introduce ES cells to the host embryo which is less difficult than blastocyst injection. Here we re-examined the condition of embryo-ES cell coculture on the aggregation method and found improvement of germ-line competent chimeric production by a simple modification of the coculture medium. Moreover, R1 ES cell and its 10 gene-manipulated subclones were tested by this method. Although all ES cell clones showed good morphology and a normal karyotype, the efficiency of chimeric development and germ-line transmission varied among clones and were classified into three grades according to germ-line competency. In the first group (class A), both the incidence of chimera with high ES cell contribution and the rate of germ-line transmission were fairly high. Germ-line competent chimeras were obtained but with rather low efficiency in the second group (class B), while another group (class C) showed an absence of high ES cell-contributed chimeras and no germ-line transmission. These results suggest the usefulness of this modified aggregation method to predict the potency of ES cell clones for germ-line competency.