The use of cationic lipids, stearylamine, or 1,2-di-(9Z-octadecen

The use of cationic lipids, stearylamine, or 1,2-di-(9Z-octadecenoyl)-3-trimethylammonium-propane (DOTAP) in liposomes promoted iloprost encapsulation to

at least 50%. The addition of cholesterol modestly reduced iloprost encapsulation. The liposomal nanoparticle formulations were tested for toxicity and pharmacologic efficacy in vivo and ex vivo, respectively. Src inhibitor The liposomes did not affect the viability of human pulmonary artery smooth muscle cells. Compared with an equivalent concentration of free iloprost, four out of the six polymer-coated liposomal formulations exhibited significantly enhanced vasodilation of mouse pulmonary arteries. Iloprost that was encapsulated in liposomes containing the polymer polyethylene glycol exhibited concentration-dependent relaxation of arteries. Strikingly, selleck chemicals half the concentration of iloprost in liposomes elicited similar pharmacologic efficacy as nonencapsulated iloprost. Cationic liposomes can encapsulate iloprost with high efficacy and can serve as potential iloprost carriers to improve its therapeutic efficacy.”
“Unsupervised image segmentation is a fundamental but challenging problem in computer vision. In this paper, we propose a novel

unsupervised segmentation algorithm, which could find diverse applications in pattern recognition, particularly in computer vision. The algorithm, named Two-stage Fuzzy c-means Hybrid Approach (TFHA), adaptively clusters image pixels according to their multichannel Gabor responses taken at multiple scales and orientations. In the first stage, the fuzzy c-means (FCM) algorithm is applied for intelligent estimation of centroid number and initialization of cluster centroids,

which endows the novel segmentation algorithm with adaptivity. To improve the efficiency of the algorithm, we utilize the Gray Level Co-occurrence Matrix (GLCM) feature extracted at the hyperpixel level instead of the pixel level to estimate centroid number and hyperpixel-cluster memberships, which are used as initialization AZD6244 cell line parameters of the following main clustering stage to reduce the computational cost while keeping the segmentation performance in terms of accuracy close to original one. Then, in the second stage, the FCM algorithm is utilized again at the pixel level to improve the compactness of the clusters forming final homogeneous regions. To examine the performance of the proposed algorithm, extensive experiments were conducted and experimental results show that the proposed algorithm has a very effective segmentation results and computational behavior, decreases the execution time and increases the quality of segmentation results, compared with the state-of-the-art segmentation methods recently proposed in the literature.

Finally, we show that HAT1 requires N-terminal tail of H4 for its

Finally, we show that HAT1 requires N-terminal tail of H4 for its stable association with this histone.”

The contributions of over-the-counter (OTC) calcium-based antacid medications and calcium-containing vitamin/mineral supplements to total calcium intake during pregnancy, MK-1775 manufacturer have rarely been assessed. This study estimates the contributions of calcium-based antacids and vitamin/mineral supplements to maternal calcium intake.\n\nMethods: Over an 8-month period, a cohort of 724 prenatal class attendees (out of a possible 1100 participants) at >28 weeks gestation in Calgary. Alberta, completed an anonymous questionnaire on vitamin/mineral supplement intake and the use of calcium-based antacids. A subset of 264 women completed a self-reported calcium-modified food frequency questionnaire.\n\nResults: The use of prenatal vitamins/minerals increased during pregnancy as did use of the single nutrients calcium and iron. Calcium-based antacids

were used by 52% (n = 365) of pregnant women. Median intake of calcium from maternal diet alone was 1619 mg/d (mean intake, 1693 +/- 94), which rose to 2084 mg/d (mean intake. 2228 116) when diet, vitamin/mineral supplements, and antacids were considered. From diet alone, 18% had less than adequate PD-1/PD-L1 Inhibitor 3 chemical structure intake (AI = 1000 mg/d) of calcium and 12% exceeded the tolerable upper intake level (UL = 2500 mg/d). Adding antacids reduced to 5% those below the AI and increased those surpassing the UL to 33%. No adverse events were

reported at calcium intakes above the UL.\n\nConclusions: Vitamin/mineral supplements and calcium-based antacids increased total maternal calcium intake, resulting in fewer women with intakes < AI but also increasing the number find more of those with intakes > UL. It is suggested that health care providers discuss all sources of nutrient intake with pregnant clients, as cumulative intakes may unintentionally exceed recommended levels.”
“Objectives: Rose hip (Rosa canina) has been used as an herbal remedy against a wide range of ailments including inflammatory disorders. The anti-inflammatory and antioxidant properties of rose hips have been evaluated in vitro and active constituents have been isolated. Rose hip contains antioxidant nutrients and an anti-inflammatory galactolipid. Rheumatoid arthritis (RA) is an inflammatory disease where activated cells release reactive oxygen substances. Thus it could be relevant to investigate if rose hip had an anti-inflammatory and/or antioxidant effect in this situation.\n\nMethods: In this open case-control study 20 female patients with RA and 10 female controls were given 10.5 g rose hip powder daily (Litozin (R)) for 28 days.

(C) 2012 Published by Elsevier Ltd “
“It was long thought th

(C) 2012 Published by Elsevier Ltd.”
“It was long thought that the colour of bird feathers does not change after plumage moult. However, there is increasing evidence that the colour of feathers may change due to abrasion, photochemical change and staining, either accidental or deliberate. The coloration of plumage due to deliberate staining, i.e. with cosmetic purposes, may help individuals to communicate their quality to conspecifics.

The presence of carotenoids in preen oils has been previously only suggested, and here we confirm for the first time its presence in such oils. Moreover, the carotenoids in the uropygial secretions were the same specific pigments found in feathers. We show not only that the colour of feathers of greater flamingos Phoenicopterus buy 4-Hydroxytamoxifen roseus became more colourful due to the application of carotenoids Nutlin-3 Apoptosis inhibitor from uropygial secretions over the plumage but also that the feathers became more colourful with the quantity of pigments applied over them,

thus providing evidence of cosmetic coloration. Flamingos used uropygial secretions as cosmetic much more frequently during periods when they were displaying in groups than during the rest of the year, suggesting that the primary function of cosmetic coloration is mate choice. Individuals with more colourful plumage initiated nesting earlier. There was a correlation between plumage coloration before and after removal of uropygial secretions from feathers’ surfaces, suggesting that the use of these pigmented secretions may function as a signal amplifier by increasing the perceptibility of plumage colour, and hence of individual quality. As the cosmetic coloration strengthens signal intensity by reinforcing base-plumage colour, its use may help to the understanding of selection for signal efficacy by making interindividual differences more apparent.”
“Objectives: Examine the longitudinal course of posttraumatic stress disorder (PTSD) in older adults and its influence on mental

health quality of life (MHQoL). Design: Evaluation performed at baseline, and 3 and 6 months postrandomization as part of a longitudinal trial. Participants and settings: A total of 1,185 participants, with a mean (+/-SD) age of 73.53 (+/-5.98) years, at seven primary care sites (including five Veterans Affairs clinics), were divided into four groups, namely, no trauma (n = 661), trauma only (n = 319), partial PTSD (n = 114), and PTSD (n = 81), based on reports of trauma and associated PTSD symptoms. Measurements: The prevalence of comorbid depression, anxiety, and alcohol use disorders, assessed using the Diagnostic and Statistical Manual, Fourth Edition, criteria and changes in MHQoL, as assessed by the Short Form-36 mental component score. Results: At baseline, the PTSD group had higher frequencies of comorbid depression and anxiety disorders and worse MHQoL than the other groups.

“An important kinetic parameter for drug efficacy is the r

“An important kinetic parameter for drug efficacy is the residence time of a compound at a drug target, which is related to the dissociation rate constant k(off). For the essential antimyco-bacterial target InhA, this parameter is most likely governed by the ordering of the flexible substrate binding loop (SBL). Whereas

the diphenyl ether inhibitors 6PP and triclosan (TCL) do not show loop ordering and thus, no slow-binding inhibition and high k(off) values, the slightly modified PT70 leads to an ordered loop and a residence time of 24 minutes. To assess the structural differences of the complexes from a dynamic point of view, molecular check details dynamics (MD) simulations with a total sampling time of 3.0 mu s were performed for three ligand-bound and two ligand-free (perturbed) InhA systems. The individual simulations show comparable Selleckchem LCL161 conformational features with

respect to both the binding pocket and the SBL, allowing to define five recurring conformational families. Based on their different occurrence frequencies in the simulated systems, the conformational preferences could be linked to structural differences of the respective ligands to reveal important determinants of residence time. The most abundant conformation besides the stable EI* state is characterized by a shift of IIe202 and Val203 toward the hydrophobic pocket of InhA. The analyses revealed potential CT99021 PI3K/Akt/mTOR inhibitor directions for avoiding this conformational change and, thus, hindering rapid dissociation: (1) an anchor group in 2′-position of the B-ring for scaffold stabilization, (2) proper occupation of the hydrophobic pocket, and (3) the introduction of a barricade sub-stituent in 5′-position of the diphenyl ether B-ring.”

dehalogenases (2-HADs) catalyse the hydrolytic dehalogenation of 2-haloalkanoic acids, cleaving the carbon-halide bond at the C-alpha-atom position and releasing a halogen atom. These enzymes are of interest for their potential use in bioremediation and in the synthesis of industrial chemicals. Here, the crystal structure of 2-HAD from Pseudomonas syringae pv. tomato DC3000 (ps-2-HAD) at 1.98 angstrom resolution solved using the single-wavelength anomalous dispersion method is reported. The ps-2-HAD molecule consists of two structurally distinct domains: the core domain and the subdomain. Enzymatic activity analysis of ps-2-HAD revealed its capacity to catalyse the dehalogenation of both L- and D-substrates; however, the structure of ps-2-HAD is completely different from that of DehI, which is the only DL-2-HAD enzyme that has been structurally characterized, but shows similar overall folding to L-HADs. Single mutations of four amino-acid residues at the putative active site showed that they are related to its enzymatic activity, yet three of them are nonconserved among HADs.

Subsequently, pDC and CD4(+) T cells, producing osteolytic cytoki

Subsequently, pDC and CD4(+) T cells, producing osteolytic cytokines, increased with tumor burden, causing severe bone damage. Microcomputed tomography and histology analyses of bone showed destruction of femur and tibia. The therapeutic significance of this finding was confirmed by depletion of pDC, which resulted in decreased tumor burden and bone loss by activating tumor-specific cytolytic CD8(+) T cells and decreasing

suppressor cell populations. Thus, pDC depletion may offer a novel adjuvant strategy to therapeutically influence breast cancer bone metastasis. The Journal of Immunology, 2012, 189: 4258-4265.”
“Advantages of telemetric devices for long-term intracranial pressure (ICP) measurement have been mentioned several times in the literature. However, descriptions of associated complications are lacking. Therefore, the presented observational study Selleckchem CA4P focused on clinical and radiological findings after insertion of an intraparenchymal telemetric ICP monitor.\n\nBetween April 2010 and February 2013, 185 telemetric ICP catheters were implanted for diagnostic purposes. All patients were clinically followed. Radiological, microbiological and clinical data Androgen Receptor inhibitor were analysed.\n\nOne brain abscess (0.5 %) and two cutaneous infections (1.1 %) occurred in 185 patients.

Staphylococcus spp. could be detected in all cases. Six patients (3.2 %) suffered from single new-onset seizures and one patient (0.5 %) from a temporary hemiparesis. Intracerebral haemorrhages occurred in 15.6 %, most of the time as small punctate bleedings. Perifocal oedematous reactions surrounding inserted telemetric catheters could be observed in 46.9 %. Multiple imaging studies revealed a tendency of complete oedema resolution over time.\n\nInfectious as well as haemorrhagic complication rates are well comparable with the common literature. The long-term implantation

of an ICP probe Smoothened Agonist does not seem to increase the risk of wound infections or brain abscess formation. Surprisingly, very high numbers of oedematous reactions after insertion of the intraparenchymal ICP monitor were seen. Reasons therefore could only be speculated upon.”
“Despite the availability of professional guidelines for the pregnancy management of women affected by female genital mutilation (FGM), this study demonstrated major deficits in identification, management and safeguarding.”
“An asthmatic girl was first hospitalized at age 2(9/12) years because of dyspnoea, lung consolidations and/or atelectasis, and rattling. Between ages 2(9/12) and 6(2/12) years, she required three hospitalizations in ICU out of nine hospitalizations for the same symptoms. Differential diagnosis of this difficult to treat asthma disclosed severe tracheomalacia and persistent asthma.

The aim of this study was to determine whether overexpression of

The aim of this study was to determine whether overexpression of the RIP3 gene could sensitize human breast cancer cells to parthenolide in vitro. Methods: The expression of RIP3 mRNA in human breast cancer cell lines (MCF-7, MDA-MB-231, MDA-MB-435 and T47D) was detected using

RT-PCR. Both MDA-MB-231 and MCF-7 cells were transfected with RIP3 expression or blank vectors via lentivirus. Cell viability was measured with MTT assay; intracellular ROS level and cell apoptosis were analyzed using flow cytometry. Results: RIP3 mRNA expression was not detected in the four human breast cancer cell lines tested. However, the transfection induced higher levels of RIP3 protein in MCF-7 and MDA-MB-231 cells. Furthermore, overexpression of RIP3 decreased the IC50 values of parthenolide from 17.6 to 12.6 GSK2399872A cost mu mol/L in MCF-7 cells; and from 16.6 to 9.9 mu mol/L in MDA-MB-231 cells. Moreover, overexpression of RIP3 significantly increased parthenolide-induced apoptosis and ROS accumulation in MCF-7 and MDA-MB-231 cells. Pretreatment with N-acetyl-cysteine abrogated the increased sensitivity of RIP3-transfected MCF-7 and MDA-MB-231 cells to parthenolide. Conclusion: Overexpression of RIP3 sensitizes MCF-7 and MDA-MB-231 breast

cancer cells to parthenolide in vitro via intracellular ROS accumulation.”
“N-2-saturated 2-propanol solutions containing styrene and maleimide

were gelled by the addition of hydroxypropylcellulose and irradiated by proton, He and C-ion beams. The trend in the dose rate and LET effects on selleck screening library the yield and molecular weight distribution of the polymer produced in the gel was almost the same in the solution. On the contrary, the dose rate effect in the gel was higher than that in the solution. This effect was accelerated for irradiations Pexidartinib in vitro by proton as well as heavier ion with a higher LET value. (C) 2014 Elsevier B.V. All rights reserved.”
“The association of white-coat hypertension (WCH) with target organ damage is still debated; in particular, the relationship of this blood pressure phenotype with subclinical vascular damage remains controversial. Thus, we carried out a systematic review and meta-analysis to provide updated information on carotid structural changes in WCH. Studies were identified using the following search terms: ‘white coat hypertension’, ‘isolated clinic hypertension’, ‘carotid artery’, ‘carotid atherosclerosis’, ‘carotid intima-media thickness’, ‘carotid damage’, ‘carotid thickening’. Full articles published in the English language in the last two decades reporting studies on adults were considered. A total of 3478 untreated patients, 940 normotensive (48% men), 666 WCH (48% men), and 1872 hypertensive individuals (57% men) included in 10 studies, were analyzed.

Many participants were prompted to seek medical advice by a famil

Many participants were prompted to seek medical advice by a family member or acquaintance. Having a transient ischaemic attack negatively changed their perception of their health and their quality check details of life, but some also

viewed it as a positive event that had warned of their stroke risk and enabled them to take up health maintenance measures. Conclusions. Having a transient ischaemic attack permanently changes peoples quality of life and their perception of their health, despite the transience of the symptoms. The ability of people to make positive health changes after a transient ischaemic attack to some extent ameliorates the negative effects of being aware of their heightened stroke risk. Their appreciation of their quality of life may also be enhanced. The transience of the symptoms and lack of knowledge of transient ischaemic attacks lead to delays in seeking medical advice.”
“Objectives: Symptoms of stress velopharyngeal incompetence (SVPI) have been reported by many wind instrument players. The current study was designed to determine (1) if symptoms of SVPI were accompanied by aeromechanical signs of SVPI and (2) if signs of SVPI differed across musical tasks.\n\nDesign:

Participants were studied during a single recording session.\n\nSetting: 17-AAG nmr The study was conducted in a university laboratory.\n\nParticipants: Participants were 10 collegiate trombone players. They were separated into two groups: six who reported symptoms of SVPI Prexasertib clinical trial and four who reported no symptoms.\n\nMain Outcome Measure: Nasal pressure recorded during trombone playing was used to determine velopharyngeal status (open or closed).\n\nResults: None of the participants exhibited an open velopharynx during trombone playing; however, all participants had positive nasal pressure (indicating an open velopharynx) immediately prior to sound onset on at least some of their breath groups. Two participants had positive nasal pressure

prior to the vast majority of their productions and were given biofeedback and instruction to change this behavior.\n\nConclusions: Symptoms of SVPI do not necessarily indicate the presence of a velopharyngeal-nasal leak during wind instrument playing but may reflect awareness of air leaks immediately prior to sound production. Pre-sound velopharyngeal-nasal air leaks may be amenable to behavioral modification by biofeedback and instruction. Nasal pressure measurement (using a nasal cannula) provides a simple, yet powerful, way to identify SVPI.”
“Steroid hormones regulate multiple but distinct aspects of social behaviors. Testosterone (T) has multiple effects on learned courtship song in that it regulates both the motivation to sing in a particular social context as well as the quality of song produced. The neural substrate(s) where T acts to regulate the motivation to sing as opposed to other aspects of song has not been definitively characterized.

0004 and 0 0032, respectively) A trend of decrease in lung adeno

0004 and 0.0032, respectively). A trend of decrease in lung adenocarcinoma risk was found in subjects with HRT harboring an increasing number of protective EGFR SNP genotypes in both blocks (P 0.0032 and 0.0046, respectively). In conclusion, HRT use may modify the association of EGFR SNPs with lung adenocarcinoma risk. The EGFR SNPs have a cumulative effect on decreasing lung adenocarcinoma risk in never-smoking women with HRT use.”
“Irgarol 1051 is an algistatic compound used in copper-based antifoulant paints. It is a widespread and persistent pollutant of

the estuarine environment. Ilyanassa obsoleta, the Eastern Androgen Receptor Antagonist screening library mud snail, is a common intertidal gastropod that inhabits mud flats and salt marshes along the east coast of North America. It is an important inhabitant of the estuarine environment; contributing to nutrient regeneration and regulating microbial processes in the sediments. The toxicity

of irgarol to estuarine gastropods has not been previously examined, although they have the potential to be exposed to antifoulants through both aqueous and sediment routes. The objectives of this study were to evaluate irgarol’s effects on I. obsoleta survival, reproductive status (imposex occurrence and testosterone levels), chemoreceptive function, learn more and cellular respiration (cytochrome-c oxidase activity). Irgarol was moderately toxic to I. obsoleta; Ilomastat research buy adult aqueous 96-h LC(50) = 3.73 mg/L, larval aqueous 96-h LC(50) = 3.16 mg/L, and adult sediment 10-day LC(50) = 12.21 mg/kg. Larval snails were not significantly more sensitive to irgarol than adult snails. A chronic 45-day aqueous irgarol exposure (0.005-2.5 mg/L) did not induce imposex or affect free-testosterone levels. The 45-day chronic LC(50) of 1.88 mg/L was significantly lower than the 96-h acute value. A 96-h acute aqueous irgarol exposure (0.375-1.5 mg/L) caused a decrease in normal response to chemosensory cues such as the presence of food or predators. There was a significant increase in cytochrome-c

oxidase activity at 2.5 mg/L, which might indicate irgarol’s disruption of the mitochondrial membrane and subsequently ATP synthesis. Although the toxicity values determined for I. obsoleta exceeded irgarol concentrations measured in surface waters, results from this toxicity assessment will provide valuable information to environmental resource managers faced with decisions regarding the use and regulation of antifoulant paints in the coastal zone.”
“Notch signaling plays crucial roles in fate determination and the differentiation of neural stem cells in embryonic and adult brains. It is now clear that the notch pathway is under more complex and dynamic regulation than previously thought.

Genes involved in jasmonic acid and reactive oxygen species produ

Genes involved in jasmonic acid and reactive oxygen species production; Ca2+ and receptor-like kinase signaling; lignin biosynthesis; and other stress-related genes were repressed in YS, whereas a large number of such stress-related genes were induced in 8424 at 120 HAT. These results suggested that repressed defense and stress response BVD-523 can save energy for better root growth in YS, which can facilitate K+ uptake and increase

K efficiency and tolerance to K+ deficiency. This study presents the first global root transcriptome in watermelon and provides new insights into the molecular mechanisms underlying tolerance to K+ deficiency of K-efficient watermelon genotypes.”
“Recently there has been growing interest in mindfulness-based cognitive-behavioral therapies in the field of disordered eating treatment as an alternative or as an adjunct to extant treatment. The aims of this review are to comprehensively

identify, summarize and critically evaluate the available outcome evidence of mindfulness-based cognitive-behavioral therapies as treatments for a range of disordered eating concerns. This review suggests that mindfulness-based interventions, especially MK-8931 ic50 modified dialectical behavior therapy, seem to be promising treatments for bulimia nervosa, binge eating disorder, and eating disorders with borderline personality disorders and substance use disorders. However, evidence is extremely limited on mindfulness-based interventions as treatments for anorexia nervosa. Limitations and future directions are also discussed in this review.”
“Humid tropical forests have the fastest rates of organic matter decomposition globally, which often coincide with fluctuating oxygen (O-2) availability in surface soils. Microbial iron (Fe) reduction generates reduced iron [Fe(II)] under anaerobic conditions, which oxidizes to Fe(III) under subsequent aerobic conditions. We demonstrate that Fe (II) oxidation stimulates organic matter decomposition via two mechanisms: (i) organic matter oxidation, likely driven by reactive oxygen species; and (ii) increased dissolved organic carbon (DOC)

availability, likely driven by acidification. Phenol oxidative activity increased linearly with Fe(II) concentrations find more (P < 0.0001, pseudo R-2 = 0.79) in soils sampled within and among five tropical forest sites. A similar pattern occurred in the absence of soil, suggesting an abiotic driver of this reaction. No phenol oxidative activity occurred in soils under anaerobic conditions, implying the importance of oxidants such as O-2 or hydrogen peroxide (H2O2) in addition to Fe(II). Reactions between Fe(II) and H2O2 generate hydroxyl radical, a strong nonselective oxidant of organic compounds. We found increasing consumption of H2O2 as soil Fe(II) concentrations increased, suggesting that reactive oxygen species produced by Fe(II) oxidation explained variation in phenol oxidative activity among samples.

001) benefited from imaginal desensitization During

001) benefited from imaginal desensitization. During GSK1210151A cost the 3-month follow-up, there was a significant additional benefit for N-acetylcysteine versus placebo

on measures of problem-gambling severity (t = 2.069; P = .043). Conclusions: N-acetylcysteine treatment during therapy facilitates long-term application of behavioral therapy techniques once patients are in the community after therapy has been completed. (C) Copyright 2013 Physicians Postgraduate Press, Inc.”
“Mealybug, Phenacoccus solenopsis Tinsley has recently emerged as a serious insect pest of cotton in India. This study demonstrates the use of Maxent algorithm for modeling the potential geographic distribution of P. solenopsis in India with presence-only data. Predictions were made based on the analysis of the relationship between 111 occurrence records for P. solenopsis and the corresponding current and future climate data defined on the study area. The climate data from worldclim database for current (1950-2000) and future (SRES A2 emission scenario for 2050) conditions were used. DIVA-GIS, an open source software for conducting spatial analysis was used for mapping the predictions from Maxent. The algorithm provided reasonable estimates of the species range indicating better discrimination of suitable and BVD-523 datasheet unsuitable areas for its occurrence in India under both present and future climatic conditions. The fit for the model as measured by AUC was high,

with value of 0.930 for the training

PP2 cost data and 0.895 for the test data, indicating the high level of discriminatory power for the Maxent. A Jackknife test for variable importance indicated that mean temperature of coldest quarter with highest gain value was the most important environmental variable determining the potential geographic distribution of P. solenopsis. The approaches used for delineating the ecological niche and prediction of potential geographic distribution are described briefly. Possible applications and limitations of the present modeling approach in future research and as a decision making tool in integrated pest management are discussed.”
“The integrity of the genome is threatened by DNA damaging events such as radiation, viral infection and chemicals. Ionizing irradiation is known to cause genotoxic damage through the generation of reactive oxygen species (ROS) and nitrogen species (RNS) and we have found that a signaling pathway for the nuclear translocation of Translin is initiated in association and efficiently blocked by a specific inhibitor of nitric oxide synthase (NOS). This suggests the involvement of inducible nitric oxide synthase (iNOS)-derived nitric oxide (NO) in the nuclear translocation of Translin. To address the functional significance of Translin in the hematopoietic generation system after ionizing irradiation, we generated Translin-deficient (Translin(-/-)) mice and examined hematopoietic colony formation after sublethal ionizing irradiation.