Induction of Gene Amplification by Arsenic Lee, Te-Chang; Tanaka, Noriho; Lamb, Patricia W. ...
Science (American Association for the Advancement of Science),
07/1988, Letnik:
241, Številka:
4861
Journal Article
Recenzirano
Arsenic is a well-established carcinogen in humans, but there is little evidence for its carcinogenicity in animals and it is inactive as an initiator or tumor promoter in two-stage models of ...carcinogenicity in mice. Two arsenic salts (sodium arsenite and sodium arsenate) induced a high frequency of methotrexate-resistant 3T6 cells, which were shown to have amplified copies of the dihydrofolate reductase gene. The ability of arsenic to induce gene amplification may relate to its carcinogenic effects in humans since amplification of oncogenes is observed in many human tumors. The inability of arsenic to induce gene mutations may relate to the negative results of arsenic in longterm animal studies and suggests that these experiments may not detect some environmental agents that act late in the carcinogenic process in humans.
DBP formation during chloramination Diehl, Alicia C.; Speitel, Gerald E.; Symons, James M. ...
Journal - American Water Works Association,
June 2000, Letnik:
92, Številka:
6
Journal Article
Recenzirano
Batch experiments were conducted on three diverse water sources to study the formation of dissolved organic halogen (DOX), trihalomethanes (THMs), haloacetic acids (HAAs), and cyanogen halides (CNX) ...during chloramination. The authors used preformed chloramines to examine the effect of pH, mass ratio of chlorine to ammonia-nitrogen (Cl₂ to N), and bromide concentration on disinfection by-product (DBP) formation. Formation of specific DBPs as well as the group parameter DOX was greatest at low pH and high Cl₂-to-N ratios and followed the general trend of decreasing with increasing pH and decreasing Cl₂-to-N ratio. Bromide addition increased the concentration of bromine-substituted DBPs and DOX. These experiments demonstrated that because of dihaloacetic acid formation, HAA formation is more problematic during chloramination than THM formation. Because the specific DBPs measured in this research (THMs, six HAAs, and CNX) accounted for no more than 35 percent of the DOX concentration, utilities may want to consider both specific DBPs and DOX in selecting appropriate chloramination conditions.
C. J. Womack, S. E. Davis, J. L. Blumer, E. Barrett, A. L. Weltman and G. A. Gaesser
Exercise Physiology Laboratory, University of Virginia, Charlottesville 22903, USA.
Seven untrained male subjects ...age 25.6 +/- 1.5 (SE) yr, peak O2 uptake
(VO2) 3.20 +/- 0.19 l/min trained on a cycle ergometer 4 days/wk for 6 wk,
with the absolute training workload held constant for the duration of
training. Before and at the end of each week of training, the subjects
performed 20 min of constant-power exercise at a power designed to elicit a
pronounced slow component of VO2 (end-exercise VO2-VO2 at minute 3 of
exercise) in the pretraining session. An additional 20-min exercise bout
was performed after training at this same absolute power output during
which epinephrine (Epi) was infused at a rate of 100 ng.kg-1.min-1 between
minutes 10 and 20. After 2 wk of training, significant decreases in VO2
slow component, end-exercise VO2, blood lactate (La- and glucose
concentrations, plasma Epi (Epi) and norepinephrine concentrations,
ventilation (VE), and heart rate (HR) were observed (P < 0.05). Although
the rapid attenuation of the VO2 slow component coincided temporally with
reductions in plasma Epi, blood La-, and VE, the infusion of Epi after
training significantly increased plasma Epi (delta 2.22 ng/ml), blood
La- (delta 2.4 mmol/l) and VE (delta 10.0 l/min) without any change in
exercise VO2. We therefore conclude that diminution of the VO2 slow
component with training is attributable to factors other than the reduction
in plasma Epi, blood La- and VE.
Plasmodium malariae in Haitian refugees, Jamaica Lindo, John F; Bryce, Jeanette Horner; Ducasse, Marion Bullock ...
Emerging infectious diseases,
06/2007, Letnik:
13, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Since 1963, reported malaria transmission in Haiti has been restricted to Plasmodium falciparum. However, screening of Haitian refugees in Jamaica in 2004, by microscopic examination, identified P. ...falciparum, P. vivax, and P. malariae. PCR confirmed the P. malariae and P. falciparum but not P. vivax infections. DNA sequencing and rRNA gene sequences showed transmission of P. malariae. This report confirms that P. malariae is still being transmitted in Haiti.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Decreased expression of the human KAI1 metastasis-suppressor gene is involved in the progression of human prostatic cancer and possibly lung and breast cancer. To evaluate the frequency of mutation ...and allelic loss during the progression of human cancer, as well as to determine the regulatory mechanism for the expression of the KAI1 gene in normal and cancerous tissues, we characterized the 5'-promoter region, exon/intron organization, and transcription initiation site of the human KAI1 gene. About 80 kb of DNA was identified as the human KAI1 gene, which contains 8 kb of 5'-region, 10 exons, 9 introns, and 8 kb of DNA following exon 10. The coding region starts in exon 3 and ends in exon 10. The size of intron 1 is 29 kb, which almost equals the sizes of all other introns combined. A CpG island is present in the 5'-promoter region and extends to exon 1 and intron 1. The promoter region has no TATA or CCAAT box but has many putative binding motifs for various transcription factors, including nine Sp1 sites and five AP2 sites. These results suggest a diverse regulatory mechanism for the expression of the KAI1 gene in human tissues. The transcription initiation site of the KAI1 gene is located 181 bp upstream of the first nucleotide of the translation initiation codon. Comparisons of gene structures between KAI1 and seven other members of the transmembrane 4 superfamily revealed that the splicing sites relative to the different structural domains of the predicted proteins are well conserved, suggesting that these genes are evolutionarily related and that they arose through gene duplication and divergent evolution.
A new device called the Lars Rotational Laxiometer (Lars Inc, Dijon, France) is introduced to aid in the diagnosis of posterolateral rotatory instability of the knee. This device assigns a ...quantitative value for tibial external rotation. Three examiners each evaluated a separate group of 30 different subjects (total 180 knees) to obtain side-to-side differences. The subjects had no history of injury, pain, or instability. An external rotation measurement was performed at 30 degrees and 90 degrees of knee flexion. At 90 degrees, the mean side-to- side difference was 4.4 degrees (range, 3.7 degrees to 5.1 degrees); at 30 degrees it was 5.5 degrees (range, 4.7 degrees to 6.3 degrees). There was no significant difference with gender or age. The purpose of this study is to establish baseline side-to-side values for the posterolateral complex in normal knees. Objective values are obtainable with the Laxiometer.
Arthroscopy 1998 Jul-Aug;14(5):489-94
Estrogenicity is an important mechanism in hormonal carcinogenesis but not sufficient to explain the carcinogenic activity of all estrogens. Additional mechanisms, related to genetic alterations, in ...conjunction with estrogenicity mediated through the estrogen receptor, have been suggested. An environmental estrogen bisphenol‐A (BP‐A) and its analogs are widespread in our living environment. Because of the potential for human exposure, the possible relationship between carcinogenicity and estrogenicity of these bisphenols was studied using mammalian cells. We quantitatively compared the cell‐transforming activity of BP‐A and 4 of its analogs (BP‐2, BP‐3, BP‐4 and BP‐5) in Syrian hamster embryo (SHE) cells lacking estrogen‐receptor expression. The transforming activity determined by the morphological transformation frequencies in SHE cells treated with the bisphenols ranked: BP‐4 > BP‐5 > BP‐3 > BP‐A > BP‐2. We also compared the estrogenicity of the 5 bisphenols in MCF7 human breast cancer cells as determined by cell proliferation or progesterone receptor (PgR) expression assayed by RT‐PCR. When MCF7 cells were treated with the bisphenols, the proliferative potency ranked: BP‐A > BP‐5 > BP‐4 > BP‐3 = BP‐2. The level of mRNA for PgR in cells treated with the bisphenols was BP‐A > BP‐5 > BP‐4 > BP‐3 > BP‐2. These indicate that the transforming activity does not correlate with the estrogenicity of the bisphenols, except for BP‐2 that has the weakest activity at the both endpoints. In addition, our results suggest that bisphenols with few, if any, transforming and estrogenic activities could be altered by a modification of the chemical structure. Published 2001 Wiley‐Liss, Inc.
A preneoplastic variant of Syrian hamster embryo cells, sup(+), exhibits decreased endoplasmic reticulum calcium levels and
subsequently undergoes apoptosis in low serum conditions (Preston, G. A., ...Barrett, J. C., Biermann, J. A., and Murphy, E.
(1997) Cancer Res . 57, 537â542). This decrease in endoplasmic reticulum calcium appears to be due, at least in part, to reduced capacitative
calcium entry at the plasma membrane. Thus we investigated whether inhibition of capacitative calcium entry per se could reduce endoplasmic reticulum calcium and induce apoptosis of cells. We find that treatment with either SKF96365 (30â100
μ m ) or cell-impermeant 1,2-bis( o -amino-5-bromophenoxy)ethane- N,N,Nâ²,Nâ² -tetraacetic acid (5â10 m m ) is able to induce apoptosis of cells in conditions where apoptosis does not normally occur. Because previous work has implicated
vesicular trafficking as a mechanism of regulating capacitative calcium entry, we investigated whether disruption of vesicular
trafficking could lead to decreased capacitative calcium entry and subsequent apoptosis of cells. Coincident with low serum-induced
apoptosis, we observed an accumulation of vesicles within the cell, suggesting deregulated vesicle trafficking. Treatment
of cells with bafilomycin (30â100 n m ), an inhibitor of the endosomal proton ATPase, produced an accumulation of vesicles, decreased capacitative entry, and induced
apoptosis. These data suggest that deregulation of vesicular transport results in reduced capacitative calcium entry which
in turn results in apoptosis.
PDF
