Topoisomerases alter DNA topology and are vital for the maintenance of genomic integrity. Topoisomerases I and II are also
targets for widely used antitumor agents. We demonstrated previously that in ...the human leukemia cell line, HL-60, resistance
to topoisomerase (topo) II-targeting drugs such as etoposide is associated with site-specific hypophosphorylation of topo
IIα. This effect can be mimicked in sensitive cells treated with the intracellular Ca 2+ chelator, 1,2-bis(2-aminophenoxy)ethane- N,N,N â², N â²-tetraacetic acid (BAPTA-AM). Here we identify Ser-1106 as a major phosphorylation site in the catalytic domain of topo IIα.
This site lies within the consensus sequence for the acidotrophic kinases, casein kinase I and casein kinase II. Mutation
of serine 1106 to alanine (S1106A) abrogates phosphorylation of phosphopeptides that were found to be hypophosphorylated in
resistant HL-60 cells or sensitive cells treated with BAPTA-AM. Purified topo IIα containing a S1106A substitution is 4-fold
less active than wild type topo IIα in decatenating kinetoplast DNA and also exhibits a 2â4-fold decrease in the level of
etoposide-stabilized DNA cleavable complex formation. Saccharomyces cerevisiae (JN394t2-4) cells expressing S1106A mutant topo IIα protein are more resistant to the cytotoxic effects of etoposide or amsacrine.
These results demonstrate that Ca 2+ -regulated phosphorylation of Ser-1106 in the catalytic domain of topo IIα modulates the enzymatic activity of this protein
and sensitivity to topo II-targeting drugs.
The fresh water unicellular green alga Chlamydomonas reinhardtii was used to explore whether it could function as a model system to identify proteins that are differentially expressed in response to ...arsenate exposure. Cells were treated with different concentrations of arsenate ranging from 100 - 400 μM. When exposed to 200 μM arsenate, the amount of live cells started to lessen on the second day and continued to diminish, indicating a toxic effect of arsenate. Proteomic analysis was used to investigate if these cells showed a specific response to arsenic-induced stress. Fifteen proteins were found that were over-expressed in the 200 μM arsenate-treated samples and two proteins were found to be very strongly over-expressed in samples treated with 400 μM. These were selected for identification using liquid chromatography coupled with tandem mass spectrometry. Oxidative stress and protein damage were the major effects as shown by the up-regulation of Mn-superoxide dismutase, an oxygen-evolving enhancer protein, a chaperonin-like protein and a heat shock protein.
The dynamic nature of the mass spectrometry (MS) experiment creates many opportunities for innovation and advance. The new ion generation methods that merited the Nobel Prize were especially ...revolutionary examples, but mass analyzer design, ion chemistry, ion detection, and data analysis have all seen significant performance advances. In the area of proteomics, the key moment for any of these innovations and advances comes when they are transferred from MS laboratory to the biomedical research laboratory. Indeed, the past 5 or so years have seen key aspects of electrospray and matrix-assisted laser desorption/ionization mature to the point that MS is now ubiqitous part of life science research and experiments that were once cutting edge have become routine. Similarly, the new methods described in this chapter are also beginning to pass this transfer test to produce unique results in a variety of biological systems.
South Carolina Women Spruill, Marjorie Julian; Littlefield, Valinda W; Johnson, Joan Marie ...
06/2012
eBook
Covering an era from the early twentieth century to the present, this volume features twenty-seven South Carolina women of varied backgrounds whose stories reflect the ever-widening array of ...activities and occupations in which women were engaged in a transformative era that included depression, world wars, and dramatic changes in the role of women. Some striking revelations emerge from these biographical portraits-in particular, the breadth of interracial cooperation between women in the decades preceding the civil rights movement and ways that women carved out diverse career opportunities, sometimes by breaking down formidable occupational barriers. Some women in the volume proceeded cautiously, working within the norms of their day to promote reform even as traditional ideas about race and gender held powerful sway. Others spoke out more directly and forcefully and demanded change. Most of the women featured in these essays were leaders within their respective communities and the state. Many of them, such as Wil Lou Gray, Hilla Sheriff, and Ruby Forsythe, dedicated themselves to improving the quality of education and health care for South Carolinians. Septima Clark, Alice Spearman Wright, Modjeska Simkins, and many others sought to improve conditions and obtain social justice for African Americans. Others, including Victoria Eslinger and Tootsie Holland, were devoted to the cause of women's rights. Louise Smith, Mary Elizabeth Massey, and Mary Blackwell Butler entered traditionally male-dominated fields, while Polly Woodham and Mary Jane Manigault created their own small businesses. A few, including Mary Gordon Ellis, Dolly Hamby, and Harriet Keyserling exercised political influence. Familiar figures like Jean Toal, current chief justice of the South Carolina Supreme Court, are included, but readers also learn about lesser-known women such as Julia and Alice Delk, sisters employed in the Charleston Naval Yard during World War II.
β‐Blockers with pharmacologic effects that differ from conventional agents might add to antihypertensive treatment options. This study evaluated a new once‐daily formulation of the β‐/α1‐blocker, ...carvedilol controlled‐release (CR), in hypertensive patients off treatment or while still taking up to 2 (non‐β‐blocker) agents. After a 4‐week run‐in phase, patients were randomized either to placebo (n=76) or carvedilol CR 20 mg (n=82), 40 mg (n=76), or 80 mg (n=86) once daily. After 6 weeks of treatment, ambulatory blood pressure monitoring was repeated to measure the primary end point of changes in mean 24‐hour diastolic blood pressure. During treatment, 24‐hour diastolic blood pressure fell in the placebo and carvedilol CR 20‐mg, 40‐mg, and 80‐mg groups by (mean + SE) 0.4±0.9, 4.4±0.9, 7.9±0.9, and 9.6±0.9 mm Hg, respectively (P≤.001, trend test for all carvedilol CR doses with placebo). Corresponding 24‐hour systolic blood pressure changes were 0.6±1.4, 6.8±1.3, 10.1±1.4, and 12.5±1.3 mm Hg, respectively (P≤.001, trend test). Diastolic blood pressure trough‐to‐peak ratios (placebo‐corrected) based on ambulatory blood pressure monitoring (trough = mean of 20‐ to 24‐hour post‐dose readings; peak = mean of 3‐ to 7‐hour post‐dose readings) for 20‐mg, 40‐mg, and 80‐mg doses were 0.73, 0.64, and 0.65, respectively. Adverse events, including clinical chemistry values, were similar in the drug‐treated and placebo groups. Carvedilol CR has a clinically meaningful defined dose‐dependent antihypertensive effect that persists throughout a 24‐hour period.
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