Synchrotron radiation Mössbauer spectra of a rotating absorber with implications for testing velocity and acceleration time dilation.

Many Mössbauer spectroscopy (MS) experiments have used a rotating absorber in order to measure the second-order transverse Doppler (TD) shift, and to test the validity of the Einstein time dilation theory. From these experiments, one may also test the clock hypothesis (CH) and the time dilation caused by acceleration. In such experiments the absorption curves must be obtained, since it cannot be assumed that there is no broadening of the curve during the rotation. For technical reasons, it is very complicated to keep the balance of a fast rotating disk if there are moving parts on it. Thus, the Mössbauer source on a transducer should be outside the disk. Friedman and Nowik have already predicted that the X-ray beam finite size dramatically affects the MS absorption line and causes its broadening. We provide here explicit formulas to evaluate this broadening for a synchrotron Mössbauer source (SMS) beam. The broadening is linearly proportional to the rotation frequency and to the SMS beam width at the rotation axis. In addition, it is shown that the TD shift and the MS line broadening are affected by an additional factor assigned as the alignment shift which is proportional to the frequency of rotation and to the distance between the X-ray beam center and the rotation axis. This new shift helps to align the disk's axis of rotation to the X-ray beam's center. To minimize the broadening, one must focus the X-ray on the axis of the rotating disk and/or to add a slit positioned at the center, to block the rays distant from the rotation axis of the disk. Our experiment, using the (57)Fe SMS, currently available at the Nuclear Resonance beamline (ID18) at the ESRF, with a rotating stainless steel foil, confirmed our predictions. With a slit installed at the rotation axis (reducing the effective beam width from 15.6 µm to 5.4 µm), one can measure a statistically meaningful absorption spectrum up to 300 Hz, while, without a slit, such spectra could be obtained up to 100 Hz only. Thus, both the broadening and the alignment shift are very significant and must be taken into consideration in any rotating absorber experiment. Here a method is offered to measure accurately the TD shift and to test the CH.

L-dex ratio in detecting breast cancer-related lymphedema: reliability, sensitivity, and specificity.

Advances in bioelectrical impedance analysis (BIA) permit the assessment of lymphedema by directly measuring lymph fluid changes. The objective of the study was to examine the reliability, sensitivity, and specificity of cross-sectional assessment of BIA in detecting lymphedema in a large metropolitan clinical setting. BIA was used to measure lymph fluid changes. Limb volume by sequential circumferential tape measurement was used to validate the presence of lymphedema. Data were collected from 250 women, including healthy female adults, breast cancer survivors with lymphedema, and those at risk for lymphedema. Reliability, sensitivity, specificity and area under the ROC curve were estimated. BIA ratio, as indicated by L-Dex ratio, was highly reliable among healthy women (ICC=0.99; 95% CI = 0.99 - 0.99), survivors at-risk for lymphedema (ICC=0.99; 95% CI = 0.99 - 0.99), and all women (ICC=0.85; 95% CI = 0.81 - 0.87); reliability was acceptable for survivors with lymphedema (ICC=0.69; 95% CI = 0.54 to 0.80). The L-Dex ratio with a diagnostic cutoff of >+7.1 discriminated between at-risk breast cancer survivors and those with lymphedema with 80% sensitivity and 90% specificity (AUC=0.86). BIA ratio was significantly correlated with limb volume by sequential circumferential tape measurement. Cross-sectional assessment of BIA may have a role in clinical practice by adding confidence in detecting lymphedema. It is important to note that using a cutoff of L-Dex ratio >+7.1 still misses 20% of true lymphedema cases, it is important for clinicians to integrate other assessment methods (such as self-report, clinical observation, or perometry) to ensure the accurate detection of lymphedema.

The effects of symptomatic seroma on lymphedema symptoms following breast cancer treatment.

It has been speculated that symptomatic seroma, or seroma requiring needle aspiration, is one of the risk factors for lymphedema symptoms following breast cancer treatment. These symptoms exert tremendous impact on patients' quality of life and include arm swelling, chest/breast swelling, heaviness, tightness, firmness, pain, numbness, stiffness, or impaired limb mobility. Our aim was to explore if symptomatic seroma affects lymphedema symptoms following breast cancer treatment. Data were collected from 130 patients using a Demographic and Medical Information interview tool, Lymphedema and Breast Cancer Questionnaire, and review of medical record. Arm swelling was verified by Sequential Circumferential Arm Measurements and Bioelectrical Impedance Spectroscopy. Data analysis included descriptive statistics, Chi-squared tests, regression, exploratory factor analysis and exploratory structural equation modeling. Thirty-five patients (27%) developed symptomatic seroma. Locations of seroma included axilla, breast, and upper chest. Significantly, more women with seroma experienced more lymphedema symptoms. A well-fit exploratory structural equation model [X2(79) = 92.15, p = 0.148; CFI = 0.97; TLI = 0.96] revealed a significant unique effect of seroma on lymphedema symptoms of arm swelling, chest/breast swelling, tenderness, and blistering (beta = 0.48, p < 0.01). Patients who developed symptomatic seroma had 7.78 and 10.64 times the odds of developing arm swelling and chest/breast swelling versus those who did not, respectively (p < 0.001). Symptomatic seroma is associated with increased risk of developing lymphedema symptoms following breast cancer treatment. Patients who develop symptomatic seroma should be considered at higher risk for lymphedema symptoms and receive lymphedema risk reduction interventions.

[Cardiotoxicity of cancer therapy]. / Kardiotoxicita onkologické lécby.

Due to advances in oncological care, the number of patients exposed to and surviving after anticancer chemotherapy is steadily increasing. Anticancer agents, however, are often associated with side-effects including cardiotoxicity which has been identified as one of the most serious and potentially life threatening complications. Cardiotoxicity manifestations range from asymptomatic alterations of heart and vasculature function to arterial hypertension, myocardial ischemia, arrhythmias (including QT-prolongation) and overt heart failure. Post-chemotherapy cardiovascular impairment has been associated with increased morbidity and may also contribute to increased mortality in these patients, both early and late after chemotherapy. This review article describes pathophysiology, clinical manifestation, diagnostic algorithms, monitoring and therapy of cardiotoxicity caused by anticancer agents. We also outline and discuss a variety of problems associated with patient management from the viewpoint of clinical cardiology according to latest published findings.

[Invasive candidiasis in selected heamatology departments in the Czech Republic and Slovakia - microbiological results of the CAN CELL project]. / Invazivní kvasinkové infekce na vybraných hematoonkologických oddeleních Czech Republic and Slovakia - microbiological results of the CAN CELL project]

BACKGROUND: The aim of our study was to analyze the spectrum and characteristic of invasive candidiasis in selected haematological departments in the Czech and Slovak Republics, and to compare minimum inhibitory concentrations (MIC) of some antifungal agents for isolates obtained. MATERIAL AND METHODS: Between 1 March 2009 and 31 October 2010, Candida strains from clinically important material obtained from patients with haematological malignancies were collected. Each isolate was biochemically identified and tested for in vitro susceptibility to three known echinocandins and amphotericin B and selected azoles using the E-test. Relevant clinical data were collected. RESULTS: The study included 63 isolates from 61 patients. The most frequently isolated species were C. albicans and C. glabrata (28 % and 19 %, respectively). However, after exclusion of isolates from bronchoalveolar lavage fluid, the percentage changed in favour of C. albicans and C. parapsilosis (25 % and 17 respectively). The MIC data showed a high susceptibility of yeasts to echinocandins and amphotericin B. Ten (16 %) strains were cross-resistant to azoles (mostly C. glabrata). CONCLUSION: Invasive candidiasis is not frequent infection complication in patients with haematological malignancies in the Czech Republic and Slovakia. Moreover, the spectrum of pathogens was similar to that described in recent international studies. However, identification of susceptible and resistant strains according to MIC could be beneficial for choice of antifungal treatment.

[Treatment of invasive candidiasis--recommendations of professional]. / Lécba invazivní kandidózy--doporucení odborných spolecností.

National working group representing clinicians (hematologists, oncologists, infection diseases and ICU specialists), microbiologists, and different special medical societies and working groups prepared evidence-based guidelines for the treatment established fungal infection--invasive candidiasis in the adult hematology and ICU patients. These guidelines updated those published in the Czech Republic in 2003-2004. Evidence criteria of the Infectious Diseases Society of America (IDSA) were used for assessing the quality of clinical trials, and EORTC/MSG Consensus Group for definitions of invasive fungal disease.

[Treatment for invasiveness aspergillosis--recommendations of professionals]. / Lécba invazivní aspergilózy--doporucení odborných spolecností.

An increasing incidence of invasive aspergillosis is observed in most immunocompromised patients, and especially patients with acute leukemia and after hematopoietic stem cell transplantation. In order to decrease the mortality due to this infection, the clinicians need to optimise their treatment choice. The objective of these guidelines is to summarize the current evidence for treatment of invasive aspergillosis. The recommendations have been developed by an expert panel following an evidence-based search of literature with regard to current recommendation of European Conference in Infections in Leukemia and Infectious Diseases Society of America.

Psychiatric and familial predictors of transition times between smoking stages: results from an offspring-of-twins study.

The modifying effects of psychiatric and familial risk factors on age at smoking initiation, rate of progression from first cigarette to regular smoking, and transition time from regular smoking to nicotine dependence (ND) were examined in 1269 offspring of male twins from the Vietnam Era Twin Registry. Mean age of the sample was 20.1 years. Cox proportional hazard regression analyses adjusting for paternal alcohol dependence and ND status and maternal ND were conducted. Both early age at first cigarette and rapid transition from initiation to regular smoking were associated with externalizing disorders, alcohol consumption, and cannabis use. Rapid escalation from regular smoking to ND was also predicted by externalizing disorders, but in contrast to earlier transitions, revealed a strong association with internalizing disorders and no significant relationship with use of other substances. Findings characterize a rarely examined aspect of the course of ND development and highlight critical distinctions in risk profiles across stages of tobacco involvement.

[Kidney involvement in light-chain deposition disease]. / Postizení ledvin na podklade nemoci z ukládání lehkých retezcu.

An overview concerning different types of kidney involvement associated with monoclonal gammapathy (MG) is given, focused on light-chain deposition disease (LCDD). Pathophysiologic basis of LCDD remains in the light-chain tissue deposition (resp. in tissue deposition of immunoglobulin's stable domain). This mechanism is typical for monoclonal immunoglobulin's overproduction as found in MG. Clinical picture of LCDD reflects multiorgan character of disorder, while renal lesions rank among the most frequent, serious and best documented ones. Clinical data referring to a group of six patients, treated in our nephrologic department are presented. Diagnosis of LCDD was established on basis of the renal biopsy finding. Renal functions were decreased at the time of diagnosis in all patients, whereas haemodialysis treatment was started in one patient. On conclusion therapeutic possibilities of LCDD are discussed, in which number symptomatic therapy of renal failure is combined with corticosteroids therapy and cytostatic therapy; prognosis of most patients remains serious.

[Sideropenic anemia as a manifestation of selective iron malabsorption]. / Sideropenická anémie jako projev selektivní malabsorbce zeleza.

The objective of the paper is to draw attention to the not very frequent and thus omitted form of sideropenic anaemia in selective iron malabsorption as the only manifestation of malabsorption syndrome in coeliac sprue. This type should be suspected when examination of blood losses is futile and oral iron administration which is usually administered empirically produces no effect. The authors present the example of two patients with severe sideropenic anaemia where the diagnosis of malabsorption was confirmed only several years after the diagnosis of sideropenic anaemia was established. Evidence of a correct conclusion was permanent normalization of haemoglobin values when the patients adhered to a gluten-free diet.

Expansions and contractions in 36-bp minisatellites by gene conversion in yeast.

The instability of simple tandem repeats, such as human minisatellite loci, has been suggested to arise by gene conversions. In Saccharomyces cerevisiae, a double-strand break (DSB) was created by the HO endonuclease so that DNA polymerases associated with gap repair must traverse an artificial minisatellite of perfect 36-bp repeats or a yeast Y' minisatellite containing diverged 36-bp repeats. Gene conversions are frequently accompanied by changes in repeat number when the template contains perfect repeats. When the ends of the DSB have nonhomologous tails of 47 and 70 nucleotides that must be removed before repair DNA synthesis can begin, 16% of gene conversions had rearrangements, most of which were contractions, almost always in the recipient locus. When efficient removal of nonhomologous tails was prevented in rad1 and msh2 strains, repair was reduced 10-fold, but among survivors there was a 10-fold reduction in contractions. Half the remaining events were expansions. A similar decrease in the contraction rate was observed when the template was modified so that DSB ends were homologous to the template; and here, too, half of the remaining rearrangements were expansions. In this case, efficient repair does not require RAD1 and MSH2, consistent with our previous observations. In addition, without nonhomologous DSB ends, msh2 and rad1 mutations did not affect the frequency or the distribution of rearrangements. We conclude that the presence of nonhomologous ends alters the mechanism of DSB repair, likely through early recruitment of repair proteins including Msh2p and Rad1p, resulting in more frequent contractions of repeated sequences.

Breast cancer: education, counseling, and adjustment--a pilot study.

The feasibility of a randomized clinical trial to implement and compare the effectiveness of three components of an intervention for women with breast cancer and their partners was tested. The intervention components, standardized education by videotape (SE), telephone counseling (TC), and education with telephone counseling (SE+TC), were designed with a complementary approach to disease management of breast cancer at each of four phases of the breast cancer experience: diagnostic, postsurgery, adjuvant therapy, and ongoing recovery. A standardized Telephone Counseling Training Manual was developed. A nonprobability sample of 12 patient-partner pairs was accrued. Four pairs were randomly assigned to each of the three intervention components. A set of questionnaires was completed by each patient and partner at baseline and following each intervention for assessment of emotional, physical, and social adjustment, and perceived support. Attrition was minimal and return rate for the completed questionnaires at all five data-collection points was high. Validation of the SE and the TC, one of the objectives, was by data from the preliminary descriptive study (Hoskins, 1990-1994), pretests and posttests for standardized education, audiotapes for each phase-specific telephone counseling session, and evaluation forms for each intervention session. The positive findings included significant changes from pre- to postmeasurement in patients' and partners' scores for the standardized education in each of the four phases. Even with the limited statistical power, the effects were marked, lending support for a full-scale randomized clinical trial, to understand better the relative treatment efficacy and differential benefit of one or some interventions over others.

The Saccharomyces cerevisiae Msh2 mismatch repair protein localizes to recombination intermediates in vivo.

Mismatch repair proteins act during double-strand break repair (DSBR) to correct mismatches in heteroduplex DNA, to suppress recombination between divergent sequences, and to promote removal of nonhomologous DNA at DSB ends. We investigated yeast Msh2p association with recombination intermediates in vivo using chromatin immunoprecipitation. During DSBR involving nonhomologous ends, Msh2p localized strongly to recipient and donor sequences. Localization required Msh3p and was greatly reduced in rad50delta strains. Minimal localization of Msh2p was observed during fully homologous repair, but this was increased in rad52delta strains. These findings argue that Msh2p-Msh3p associates with intermediates early in DSBR to participate in the rejection of homeologous pairing and to stabilize nonhomologous tails for cleavage by Rad1p-Rad10p endonuclease.

DNA length dependence of the single-strand annealing pathway and the role of Saccharomyces cerevisiae RAD59 in double-strand break repair.

A DNA double-strand break (DSB) created by the HO endonuclease in Saccharomyces cerevisiae will stimulate recombination between flanking repeats by the single-strand annealing (SSA) pathway, producing a deletion. Previously the efficiency of SSA, using homologous sequences of different lengths, was measured in competition with that of a larger repeat further from the DSB, which ensured that nearly all cells would survive the DSB if the smaller region was not used (N. Sugawara and J. E. Haber, Mol. Cell. Biol. 12:563-575, 1992). Without competition, the efficiency with which homologous segments of 63 to 205 bp engaged in SSA was significantly increased. A sequence as small as 29 bp was used 0.2% of the time, and homology dependence was approximately linear up to 415 bp, at which size almost all cells survived. A mutant with a deletion of RAD59, a homologue of RAD52, was defective for SSA, especially when the homologous-sequence length was short; however, even with 1.17-kb substrates, SSA was reduced fourfold. DSB-induced gene conversion also showed a partial dependence on Rad59p, again being greatest when the homologous-sequence length was short. We found that Rad59p plays a role in removing nonhomologous sequences from the ends of single-stranded DNA when it invades a homologous DNA template, in a manner similar to that previously seen with srs2 mutants. Deltarad59 affected DSB-induced gene conversion differently from msh3 and msh2, which are also defective in removing nonhomologous ends in both DSB-induced gene conversion and SSA. A msh3 rad59 double mutant was more severely defective in SSA than either single mutant.

Recombination: a frank view of exchanges and vice versa.

The study of double-strand chromosome break repair by homologous and nonhomologous recombination is a growth industry. In the past year, there have been important advances both in understanding the connection between recombination and DNA replication and in linking recombination with origins of human cancer. At the same time, a combination of biochemical, genetic, molecular biological, and cytological approaches have provided a clearer vision of the specific functions of a variety of recombination proteins.

Inducers of cytochrome P450 2E1 enhance methotrexate-induced hepatocytoxicity.

OBJECTIVES: To study the effect of cytochrome P450 2E1-inducers on methotrexate (MTX)-induced cytotoxicity in human hepatocytes, and investigate the role of silymarin in preventing this toxicity. DESIGN AND METHODS: Cells were exposed to MTX in the presence of either ethanol (EtOH) or acetaminophen (APAP), or either combined with silymarin (S). Apoptosis and necrosis were measured by analyzing 6000 cells/sample using transmission electron microscopy, while cytokine release and apoptosis were quantitated by ELISA. Cytokine expression was measured by RT-PCR. Gluthatione (GSH) content was determined in cytosolic (c) and mitochondrial (m) fractions. RESULTS: MTX+EtOH and MTX+APAP increased MTX cytotoxicity 2.9-fold and 1.9-fold, respectively. S abolished this toxicity. MTX + EtOH increased the release of IL 6, IL 8 and TNF alpha by 1.0, 1.2, and 1.1 times, respectively. Cytokine expression was upregulated versus control for IL 6 (22%), IL 8 (38%), and TNF alpha (29%). Addition of 0.5 mmol/L S downregulated TNF alpha expression and reduced cytokine release. TNF alpha increased cytotoxicity by 22%, while anti-TNFalpha antibody eradicated it. MTX+EtOH depleted 45% mGSH (0 < 0.001) while S replenished it to 87% (p < 0.001), when both were compared to control levels. CONCLUSIONS: Cytochrome P450 2E1-inducers contribute to increase oxidative stress in MTX-exposed cells by increasing TNF alpha and depleting both cGSH and mGSH. This enhances MTX-cytotoxicity and promotes apoptosis.

Separation-of-function mutations in Saccharomyces cerevisiae MSH2 that confer mismatch repair defects but do not affect nonhomologous-tail removal during recombination.

Yeast Msh2p forms complexes with Msh3p and Msh6p to repair DNA mispairs that arise during DNA replication. In addition to their role in mismatch repair (MMR), the MSH2 and MSH3 gene products are required to remove 3' nonhomologous DNA tails during genetic recombination. The mismatch repair genes MSH6, MLH1, and PMS1, whose products interact with Msh2p, are not required in this process. We have identified mutations in MSH2 that do not disrupt genetic recombination but confer a strong defect in mismatch repair. Twenty-four msh2 mutations that conferred a dominant negative phenotype for mismatch repair were isolated. A subset of these mutations mapped to residues in Msh2p that were analogous to mutations identified in human nonpolyposis colorectal cancer msh2 kindreds. Approximately half of the these MMR-defective mutations retained wild-type or nearly wild-type activity for the removal of nonhomologous DNA tails during genetic recombination. The identification of mutations in MSH2 that disrupt mismatch repair without affecting recombination provides a first step in dissecting the Msh-effector protein complexes that are thought to play different roles during DNA repair and genetic recombination.

Multiple pathways of recombination induced by double-strand breaks in Saccharomyces cerevisiae.

The budding yeast Saccharomyces cerevisiae has been the principal organism used in experiments to examine genetic recombination in eukaryotes. Studies over the past decade have shown that meiotic recombination and probably most mitotic recombination arise from the repair of double-strand breaks (DSBs). There are multiple pathways by which such DSBs can be repaired, including several homologous recombination pathways and still other nonhomologous mechanisms. Our understanding has also been greatly enriched by the characterization of many proteins involved in recombination and by insights that link aspects of DNA repair to chromosome replication. New molecular models of DSB-induced gene conversion are presented. This review encompasses these different aspects of DSB-induced recombination in Saccharomyces and attempts to relate genetic, molecular biological, and biochemical studies of the processes of DNA repair and recombination.