Fanconi anemia (FA) cells exhibit hypersensitivity to DNA interstrand cross-links (ICLs) and high levels of chromosome instability. FA gene products have been shown to functionally or physically ...interact with BRCA1, RAD51 and the MRE11/RAD50/NBS1 complex, suggesting that the FA complex may be involved in the repair of DNA double-strand breaks (DSBs). Here, we have investigated specifically the function of the FA group A protein (FANCA) in the repair of DSBs in mammalian cells. We show that the targeted deletion of Fanca exons 37–39 generates a null for Fanca in mice and abolishes ubiquitination of Fancd2, the downstream effector of the FA complex. Cells lacking Fanca exhibit increased chromosomal aberrations and attenuated accumulation of Brca1 and Rad51 foci in response to DNA damage. The absence of Fanca greatly reduces gene-targeting efficiency in mouse embryonic stem (ES) cells and compromises the survival of fibroblast cells in response to ICL agent treatment. Fanca-null cells exhibit compromised homology-directed repair (HDR) of DSBs, particularly affecting the single-strand annealing pathway. These data identify the Fanca protein as an integral component in the early step of HDR of DSBs and thereby minimizing the genomic instability.
This paper presents an application for chaotic motion identification in a measured signal obtained in an experiment. The method of state space reconstruction with delay co-ordinates with the dynamic ...evolution described by a map is used. Poincaré diagrams, correlation dimensions and Lyapunov exponents are obtained as tools for deciding about the existence of chaotic behaviour. The method is applied to measurements of the lateral displacement of a vertical rotor experiencing rubbing and in some signals chaos is observed. The work concludes that the possibility of chaotic motion is well determined with the observation of Poincaré diagrams and computation of Lyapunov exponents. Correlation dimensions computations, strongly influenced by noise, are not convenient tools for investigation of chaotic behaviour in signals generated by mechanical systems.
The research groups at Drexel University and Thomas Jefferson University had proposed the use of non-Rayleigh statistics for tissue characterization. Previous work based on the hypothesis that the ...envelope of the backscattered echosignal from abnormal regions of the tissue is more likely to be K-distributed than Rayleigh distributed, used the parameter of the K-distribution, M, to distinguish between regions containing benign or malignant masses and normal ones. In this work the B-scan breast images of 19 patients were studied using this approach. Previous studies have also been extended to exploit the existence of non-uniform phase characteristics of the echosignal from scatterers with some regular spacings, such as those in a periodic or quasi-periodic alignment. Computer simulations were carried out to show that the phase statistics deviate significantly from uniform in the range of {0, 2π} if the imaging region contained a number of periodically aligned (regular lattice) scatterers along with a collection of randomly distributed scatterers resulting in a quasi-periodic arrangement. This methodology was then applied to B-scan images of the breasts to distinguish between benign and malignant masses. If benign lesions show some sort of quasi-periodic or regular structures in the tissue, they will present non-uniform phase characteristics while more randomly structured malignant masses will have uniform phase characteristics. It is seen that the K-distribution may be used to identify the abnormal regions in the breast images and information on the phase may be used to further separate the abnormal regions into benign and malignant ones.
Background:
The employment of the iron chelator deferasirox (DFX) in transfusion‐dependent patients affected by chronic anaemias occurring in several hematological diseases occasionally results in ...recovery of hematopoiesis with hematopoietic stem cells (HSCs) regaining the ability to differentiate into mature blood cells. Despite a growing body of clinical evidence, the mechanism explaining this interesting peculiarity still remains elusive.
Aims:
Aim of this study was to identify a general molecular mechanism underlying DFX beneficial effect on hematopoiesis both in healthy and in pathological conditions.
Methods:
Human healthy HSCs and two leukemia cell lines, Kasumi‐1 and K562, were treated with DFX 100 μM. N‐Acetyl Cysteine (NAC) was added as antioxidant; fludarabine was administered to inhibit STAT1 activation and interferon signaling. In vitro colony‐forming assays were assessed both in healthy and in leukemia cells to functionally test DFX ability to induce differentiation; the growth of CFU‐GM, BFU‐E and CFU‐GEMM colonies was scored and enumerated. Intracellular and mitochondrial reactive oxygen species (ROS) were assessed by cytofluorimetric analysis after DFX treatment for 24 h. The following differentiation markers were monitored after 24 h and 48 h of DFX treatment by cytofluorimetric analysis: CD14‐APC and CD36‐FITC for Kasumi‐1 cells; CD71‐FITC and CD36‐FITC for K562. Gene expression profile was performed on healthy HSCs using Illumina platform and data were analyzed by Ingenuity Pathway Analysis (IPA); differently expressed genes were validated both in healthy and leukemia cells by Realtime PCR. The expression and phosphorylation state of STAT1 were assessed by western blotting.
Results:
DFX, at clinically relevant concentrations, increased the clonogenic capacity of healthy human CD34+ HSC to form erythroid colonies in a ROS dependent fashion and the whole gene expression analysis of DFX‐treated HSCs unveiled up‐regulation of genes linked to interferon (IFN) signaling. The study, extended on human‐derived leukemia cell lines, revealed a DFX‐mediated overproduction of mitochondria‐generated reactive oxygen species (ROS), accompanied by a ROS‐dependent up‐regulated expression of specific markers of hematopoietic commitment. Similarly to HSCs, DFX treatment of Kasumi‐1 and K562 resulted in a significant up‐regulation of IFN‐related genes expression as well as in a marked hyper‐phosphorylation of the signal transducer and activator of transcription 1 (STAT1), known to be involved, in turn, in the IFN signaling. Most notably, treatment of Kasumi‐1 and K562 cell lines with the antioxidant NAC completely prevented the DFX‐mediated phosphorylation of STAT1 as well as the expression of the IFN‐stimulated genes. Conversely, the inhibition of STAT‐1 alone, by Fludarabine, was not sufficient to affect differentiation processes in both cell lines.
Summary/Conclusion:
The novel findings here reported suggest a hitherto strong impact of ROS signaling and strengthen its role as master regulator of multiple orchestrated events triggered by DFX, like IFN pathway up‐regulation and differentiation induction. Interestingly, DFX property seems to be independent on the physiological or pathological state of the cells. The identification of key factors earlier modulated by DFX and able to activate downstream events involved in the regulation of cell survival, proliferation and differentiation, provides new insights that can be developed to anticipate its administration or to extend the use of the drug also to other categories of patients.
Different Helicobacter pylori lipopolysaccharides (LPSs) and LPS-derivatives were studied for their ability to induce the production of procoagulant activity (PCA) and plasminogen activator inhibitor ...type 2 (PAI-2) by human blood mononuclear leukocytes. Smooth (S)- and rough (R)-form LPSs caused a similar increase in cell-associated PCA (tissue factor) and PAI-2 antigen release. Both effects were potentiated by fetal bovine serum via a CD14-mediated mechanism. The potency of H. pylori LPSs was ∼1000-fold lower than that of Salmonella typhimurium LPSs. When H. pylori LPS derivatives (dephosphorylated R-LPS, S-lipid A, and R-lipid A) were used, PCA and PAI-2 production were markedly reduced. R-lipid A was ∼4-fold less efficient than S-lipid A. These findings suggest that the induction of monocyte tissue factor and PAI-2 by H. pylori LPS is influenced by the lipid A structure and modulated by the core oligosaccharide and that phosphate groups present in both regions may play an important role.
Introduction: The current nutritional transition process contributes further to accelerate the onset of metabolic disorders, as do a number of environmental factors that lead to the diagnosis of ...chronic diseases, as a diet of low nutritional value, is possibly related to the incidence of metabolic syndrome. In addition to these factors, metabolic syndrome may also be related to genetic factors, the ADIPOQ + 45T> G polymorphism has been associated with serum adiponectin levels, insulin sensitivity, and obesity, which affects adiponectin levels act as protective factor for cardiovascular disease. In this way, the present study aimed to analyze the possible association between the ADIPOQ + 45T> G gene polymorphism, usual diet and metabolic syndrome in the elderly. Methods: We evaluated inflammatory and biochemical markers compared with older age groups (age 60 years) with and without metabolic syndrome. In addition to the anthropometric measurements of weight, height and waist circumference, the ADIPOQ + 45T> G gene polymorphism was determined by PCR- RFLP, and food consumption was investigated using a food frequency questionnaire. Results: The study included 111 elderly individuals. Our main results show that there was a significant relationship between the habitual consumption of milk for the group that had metabolic syndrome (p < 0.05). HDL-c levels, glucose, triglycerides, diastolic blood pressure and weight, height and waist circumference had to be altered in patients with metabolic syndrome. There was an association between habitual dietary intake of white meat with haplotypes TG and GG. Conclusion: We conclude that the relationship between the habitual consumption of certain food groups and ADIPOQ indicates the need for further studies to develop a better understanding of this relationship; however, there was no association between the ADIPOQ + 45T> G gene polymorphism and metabolic syndrome in the group of elderly studied.
In order to examine whether different connexin gene species exert different degrees of tumor-suppressing activity, we characterized growth characteristics of a gap junction-deficient human cancer ...cell line, HeLa cells, before and after transfection with cDNA for three different connexins, connexin (cx) 26, cx 40, and cx 43. All transfected cell lines (3 clones transfected with the cx 26 gene, 2 clones with cx 40, and 1 with cx 43) showed establishment of gap junctional intercellular communication (GJIC). Two of the cx 26-transfected clones showed significantly slower growth compared with the parental HeLa cells. When transfectants were grown in soft agar, the three cx 26-transfected clones grew much less than the other transfectants and parent HeLa cells. When injected into nude mice, the two cx 26 clones which exhibited the highest amount of cx 26 transcript induced almost no tumors, whereas other transfectants, including the cx 26 clone which exhibited the lowest amount of cx 26 transcript, were tumorigenic. Among transfectants of various connexin genes, there was no good inverse correlation between their GJIC and tumorigenicity. GJIC levels were significantly higher in tumors induced in nude mice by clone cx 26 A and E transfectants. These results suggest that all of the connexin genes examined could induce recovery of GJIC of HeLa cells, but only the cx 26 gene exerts strong negative growth control on HeLa cells; thus, this connexin gene may have different functions from other connexin genes.
To determine the safety and efficacy of ferumoxtran 10-enhanced magnetic resonance (MR) imaging for diagnosis of metastases to lymph nodes and the clinical usefulness of ferumoxtran 10 in nodal ...staging.
One hundred fifty-two patients were injected with ferumoxtran 10. Readers independently evaluated precontrast MR images by using node size criteria and subjective assessment of other imaging features. Ferumoxtran 10-enhanced MR images were evaluated alone and paired with precontrast images for comparison. The diagnostic performances of precontrast MR size criteria and postcontrast MR imaging were evaluated with receiver operating characteristic (ROC) analysis. Lymph node signal intensity was correlated with histopathologic findings. MR imaging and histopathologic nodal stages were compared.
Node-level sensitivity, specificity, and accuracy of precontrast MR imaging were 54%, 82%, and 68%, respectively, with node size criterion alone; 91%, 51%, and 71%, respectively, with subjective reader assessment; 85%, 85%, and 85%, respectively, with postcontrast MR imaging alone; and 83%, 77%, and 80%, respectively, with paired pre- and postcontrast MR imaging. Compared with size criteria, subjective reader assessment had higher sensitivity but substantially lower specificity. Areas under the ROC curve for pre- and postcontrast MR imaging were 0.76 and 0.83, respectively. Nonmetastatic nodes had significantly lower signal intensity than metastatic nodes on postcontrast T2-weighted MR images (P <.001). Postcontrast nodal staging was significantly more accurate than precontrast nodal staging (P <.01). Headache, back pain, vasodilatation, and urticaria each occurred in 6% of patients.
Ferumoxtran 10-enhanced MR imaging was safe and effective and facilitated improved diagnostic performance. Use of iron oxide-enhanced MR imaging increased the positive predictive value by 20% and the accuracy by 14% compared with reader assessment. Differentiating patients with no nodal metastatic involvement was more reliable with ferumoxtran 10-enhanced MR imaging than with precontrast MR imaging.
This study was designed to determine if complementary ultrasound (US) imaging and Doppler could decrease the number of biopsies for benign masses. A total of 761 breast masses were sequentially ...scored on a level of suspicion (LOS) of 1–5, where 1 represented low, and 5 was a high suspicion of malignancy, for mammography, US, and color flow with pulse Doppler (DUS). After biopsy, the results were analyzed using 2 × 2 contingency tables and ROC analysis, for mammography alone and in combination with US and DUS. The addition of US increased the specificity from 51.4% to 66.4% at a prevalence of 31.3% malignancy. ROC analysis showed that the addition of US significantly improved the performance over mammography alone in women < 55 years old (
p = 0.049); > 55 years old (
p = 0.029); masses < 1 cm (
p = 0.016) and masses > 1 cm (
p = 0.016). These results show that the addition of US to mammography alone could substantially reduce the number of breast biopsies for benign disease. (E-mail: Kenneth.Taylor@yale.edu)
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