The role of RNF138 in DNA end resection is regulated by ubiquitylation and CDK phosphorylation.

Double-strand breaks (DSBs) are DNA lesions that pose a significant threat to genomic stability. The repair of DSBs by the homologous recombination (HR) pathway is preceded by DNA end resection, the 5' to 3' nucleolytic degradation of DNA away from the DSB. We and others previously identified a role for RNF138, a really interesting new gene finger E3 ubiquitin ligase, in stimulating DNA end resection and HR. Yet, little is known about how RNF138's function is regulated in the context of DSB repair. Here, we show that RNF138 is phosphorylated at residue T27 by cyclin-dependent kinase (CDK) activity during the S and G2 phases of the cell cycle. We also observe that RNF138 is ubiquitylated constitutively, with ubiquitylation occurring in part on residue K158 and rising during the S/G2 phases. Interestingly, RNF138 ubiquitylation decreases upon genotoxic stress. By mutating RNF138 at residues T27, K158, and the previously identified S124 ataxia telangiectasia mutated phosphorylation site (Han et al., 2016, ref. 22), we find that post-translational modifications at all three positions mediate DSB repair. Cells expressing the T27A, K158R, and S124A variants of RNF138 are impaired in DNA end resection, HR activity, and are more sensitive to ionizing radiation compared to those expressing wildtype RNF138. Our findings shed more light on how RNF138 activity is controlled by the cell during HR.

Unravelling the Role of PARP1 in Homeostasis and Tumorigenesis: Implications for Anti-Cancer Therapies and Overcoming Resistance.

Detailing the connection between homeostatic functions of enzymatic families and eventual progression into tumorigenesis is crucial to our understanding of anti-cancer therapies. One key enzyme group involved in this process is the Poly (ADP-ribose) polymerase (PARP) family, responsible for an expansive number of cellular functions, featuring members well established as regulators of DNA repair, genomic stability and beyond. Several PARP inhibitors (PARPi) have been approved for clinical use in a range of cancers, with many more still in trials. Unfortunately, the occurrence of resistance to PARPi therapy is growing in prevalence and requires the introduction of novel counter-resistance mechanisms to maintain efficacy. In this review, we summarize the updated understanding of the vast homeostatic functions the PARP family mediates and pin the importance of PARPi therapies as anti-cancer agents while discussing resistance mechanisms and current up-and-coming counter-strategies for countering such resistance.

Cellular mechanism of action of 2-nitroimidazoles as hypoxia-selective therapeutic agents.

Solid tumours are often poorly oxygenated, which confers resistance to standard treatment modalities. Targeting hypoxic tumours requires compounds, such as nitroimidazoles (NIs), equipped with the ability to reach and become activated within diffusion limited tumour niches. NIs become selectively entrapped in hypoxic cells through bioreductive activation, and have shown promise as hypoxia directed therapeutics. However, little is known about their mechanism of action, hindering the broader clinical usage of NIs. Iodoazomycin arabinofuranoside (IAZA) and fluoroazomycin arabinofuranoside (FAZA) are clinically validated 2-NI hypoxic radiotracers with excellent tumour uptake properties. Hypoxic cancer cells have also shown preferential susceptibility to IAZA and FAZA treatment, making them ideal candidates for an in-depth study in a therapeutic setting. Using a head and neck cancer model, we show that hypoxic cells display higher sensitivity to IAZA and FAZA, where the drugs alter cell morphology, compromise DNA replication, slow down cell cycle progression and induce replication stress, ultimately leading to cytostasis. Effects of IAZA and FAZA on target cellular macromolecules (DNA, proteins and glutathione) were characterized to uncover potential mechanism(s) of action. Covalent binding of these NIs was only observed to cellular proteins, but not to DNA, under hypoxia. While protein levels remained unaffected, catalytic activities of NI target proteins, such as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the detoxification enzyme glutathione S-transferase (GST) were significantly curtailed in response to drug treatment under hypoxia. Intraperitoneal administration of IAZA was well-tolerated in mice and produced early (but transient) growth inhibition of subcutaneous mouse tumours.

BMI-1 regulates DNA end resection and homologous recombination repair.

BMI-1 is an essential regulator of transcriptional silencing during development. Recently, the role of BMI-1 in the DNA damage response has gained much attention, but the exact mechanism of how BMI-1 participates in the process is unclear. Here, we establish a role for BMI-1 in the repair of DNA double-strand breaks by homologous recombination (HR), where it promotes DNA end resection. Mechanistically, BMI-1 mediates DNA end resection by facilitating the recruitment of CtIP, thus allowing RPA and RAD51 accumulation at DNA damage sites. Interestingly, treatment with transcription inhibitors rescues the DNA end resection defects of BMI-1-depleted cells, suggesting BMI-1-dependent transcriptional silencing mediates DNA end resection. Moreover, we find that H2A ubiquitylation at K119 (H2AK119ub) promotes end resection. Taken together, our results identify BMI-1-mediated transcriptional silencing and promotion of H2AK119ub deposition as essential regulators of DNA end resection and thus the progression of HR.

Adhesion Optimization between Incompatible Polymers through Interfacial Engineering.

Additive manufacturing technologies such as fused filament fabrication (FFF) open many possibilities in terms of product functionality, including the possibility to integrate a sensor in FFF parts to perform structural health monitoring. In this context, embedding fiber Bragg grating (FBG) sensors into 3D-printed polymeric structures for strain or temperature measurements has attracted increasing attention in recent years. Indeed, offering structural health monitoring functionality can optimize the maintenance cost and increase security compared with conventional materials. However, the transmission of strain and temperature between the polymeric matrix and the FBG polymer jacket requires optimal bonding between them. In this work, the two polymers of interest are polyimide (PI) and poly(lactic acid) (PLA) for the FBG jacket and printed polymer, respectively. The current study investigates the influence of different surface treatment methods on the adhesion between a PI film and a plate of PLA, with PLA and PI being incompatible polymers. The adhesion promotion applied to the PI surface relies on cleaning, plasma activation, roughness modification, or the use of adhesive nanocoating. Bilayer samples of PI-PLA are processed by welding PLA against the treated PI by heating, whereas the adhesion between PI and PLA is measured by peel testing. It is observed that the highest adhesion between PI and PLA is achieved by a combination of mechanical abrasion increasing roughness and the use of polydopamine as an adhesive. This finding is discussed based on a synergetic effect between mechanical interlocking and chemical interaction between the two counterfaces.

Fused Filament Fabrication of Polymers and Continuous Fiber-Reinforced Polymer Composites: Advances in Structure Optimization and Health Monitoring.

3D printed neat thermoplastic polymers (TPs) and continuous fiber-reinforced thermoplastic composites (CFRTPCs) by fused filament fabrication (FFF) are becoming attractive materials for numerous applications. However, the structure of these materials exhibits interfaces at different scales, engendering non-optimal mechanical properties. The first part of the review presents a description of these interfaces and highlights the different strategies to improve interfacial bonding. The actual knowledge on the structural aspects of the thermoplastic matrix is also summarized in this contribution with a focus on crystallization and orientation. The research to be tackled to further improve the structural properties of the 3D printed materials is identified. The second part of the review provides an overview of structural health monitoring technologies relying on the use of fiber Bragg grating sensors, strain gauge sensors and self-sensing. After a brief discussion on these three technologies, the needed research to further stimulate the development of FFF is identified. Finally, in the third part of this contribution the technology landscape of FFF processes for CFRTPCs is provided, including the future trends.

SUMOylation mediates CtIP's functions in DNA end resection and replication fork protection.

Double-strand breaks and stalled replication forks are a significant threat to genomic stability that can lead to chromosomal rearrangements or cell death. The protein CtIP promotes DNA end resection, an early step in homologous recombination repair, and has been found to protect perturbed forks from excessive nucleolytic degradation. However, it remains unknown how CtIP's function in fork protection is regulated. Here, we show that CtIP recruitment to sites of DNA damage and replication stress is impaired upon global inhibition of SUMOylation. We demonstrate that CtIP is a target for modification by SUMO-2 and that this occurs constitutively during S phase. The modification is dependent on the activities of cyclin-dependent kinases and the PI-3-kinase-related kinase ATR on CtIP's carboxyl-terminal region, an interaction with the replication factor PCNA, and the E3 SUMO ligase PIAS4. We also identify residue K578 as a key residue that contributes to CtIP SUMOylation. Functionally, a CtIP mutant where K578 is substituted with a non-SUMOylatable arginine residue is defective in promoting DNA end resection, homologous recombination, and in protecting stalled replication forks from excessive nucleolytic degradation. Our results shed further light on the tightly coordinated regulation of CtIP by SUMOylation in the maintenance of genome stability.

Ischemic post-conditioning is neuroprotective even at delayed tPA administration after embolic stroke in female rats.

Objectives: Delayed tissue plasminogen activator (tPA) thrombolysis is accompanied by different complications in stroke patients. Studies reported sex differences in stroke therapy. Ischemic postconditioning (PC) unveils neuroprotection in stroke models. In this study, we investigate the combined effect of delayed tPA therapy and PC procedure during an embolic stroke experimental model in female rats. Materials and Methods: Female Wistar rats were randomly divided into control (saline), tPA, PC, and tPA+PC groups after stroke induction via clot injection to the middle cerebral artery. tPA treatment was initiated 6 hr after stroke, and PC procedure was performed 6.5 hr post-ischemia induction (occlusion: 10 sec; reopening: 30 sec; 5 cycles). The cerebral blood flow (CBF) was recorded up to 60 min from IV tPA injection time. The parameters of brain edema, infarct volume, disruption of the blood-brain barrier (BBB), behavioral tests, and matrix metalloproteinases-9 (MMP-9) were evaluated. Results: This study revealed that PC conduction prevents excessive CBF increase by tPA and played a protective role in infarct volume reduction (P<0.05). The combination of PC and tPA reduced the infarct volume, brain edema, and protected BBB. tPA+PC could alleviate neurobehavioral disorders compared with control or tPA. Moreover, PC had the capability of MMP-9 reduction when combined with delayed tPA (P<0.05). Conclusion: Conduction of PC not only alleviated some stroke complications but also enhanced the therapeutic time window of tPA in female rats under embolic stroke.

Zataria multiflora extract reverses lipopolysaccharide-induced anxiety and depression behaviors in rats.

OBJECTIVE: Stressors have an important role in sickness behaviors. We checked the effect of Zataria multiflora (ZM) extract against lipopolysaccharide (LPS)-induced anxiety and depression behaviors in rats. MATERIALS AND METHODS: Rats were distributed in the following groups (n=10): Control, LPS (1 mg/kg), LPS-ZM50, LPS-ZM100 and LPS-ZM200. LPS was syringed intraperitoneally (ip) 2 hr before performing behavioral tests. LPS-ZM groups were treated with 50, 100 and 200 mg/kg (ip) of ZM extract 30 min before LPS administration. Open field (OF), elevated plus maze (EPM) and forced swimming (FS) tests were done. White blood cell (WBC) was counted in all groups. RESULTS: In OF, pretreatment with ZM extract augmented the number of lines crossed and traveled distance in central and peripheral areas. The rats treated with ZM extract spent more time in the central zone and less time in the peripheral area compared to the LPS group. In EPM, the number of entries into the open and closed arms and stop time in the open arms in LPS-ZM groups were higher than the LPS group. The stop time in the closed arms of ZM-LPS groups was less than the LPS group. In FS test, swimming and climbing time in groups treated with ZM extract was more than the LPS group while their immobility time was less. WBC count in the LPS-ZM100 and LPS-ZM200 was lower than that of the LPS group. CONCLUSION: Based on the results, pretreatment with ZM extract restituted anxiety and depression caused by LPS in rats. This effect of ZM was associated with amelioration of LPS-promoted inflammation.

Caregiver Burden and Spiritual Well-being in Caregivers of Hemodialysis Patients.

The number of hemodialysis patients is increasing worldwide, and the caregivers of these patients experience a great burden. This study was conducted to examine the relationship between caregiver burden and spiritual well-being in caregivers of hemodialysis patients in Kerman, Iran. This correlational study was conducted on 382 caregivers of hemodialysis patients. Data were collected using the Caregiver Burden Inventory (24 items) and Ellison and Paloutzian 20-Item Spiritual Well-being Questionnaire. Data were analyzed by descriptive and inferential statistics (t test, ANOVA, Spearman correlation, and linear regression analysis) in SPSS 20 software. The findings showed that 45 (11.8%) caregivers had mild, 214 (56%) moderate, and 123 (32.2%) high caregiver burden. Furthermore, 1 (0.3%) caregiver had mild, 349 (92.4%) moderate, and 32 (8.4%) high spiritual well-being. Also, Spearman correlation test showed a significant reveres relationship between caregiver burden and spiritual well-being scores (p < 0.001, r = - 0.41). Moreover, the results of the regression analysis showed that the patient's income, frequency of patient dialysis per week, and patient's need to receive care and spiritual well-being were predictors of caregiver burden, which explained 41% of the burden in caregivers. The results of this study revealed that spiritual well-being was negatively related to caregiver burden and was one of its predictors. Therefore, spirituality can be used as a low-cost and effective intervention to reduce the caregiver's burden.

Association of VDR gene polymorphisms with risk of relapsing-remitting multiple sclerosis in an Iranian Kurdish population.

PURPOSE: The purpose of this study was to evaluate the association of VDR Apa-I, Bsm-I, Fok-I, Taq-I single nucleotide polymorphisms (SNPs) with multiple sclerosis (MS) risk in an Iranian Kurdish population. MATERIALS AND METHODS: A population including of 118 patients and 124 healthy matched controls were recruited to the study. Genotyping of the SNPs was accomplished using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: The frequency of allele T of Fok-I (P = 0.003) and allele C of Taq-I (P = 0.0003) was significantly different between case and control subjects and showed significant association with risk of MS (OR = 1.84, 95% CI = 1.23-2.76; OR = 1.98, 95% CI = 1.36-2.87, respectively). CT genotype (OR = 1.7, 95% CI = 1.05-2.99) of Fok-I and CC genotype (OR = 2.18, 95% CI = 1.05-4.52) of Taq-I showed a predisposing effect. Combined TT+TC vs. CC for Fok-I (OR = 2.15, 95% = CI 1.29-3.60) and combined CC+TC vs. TT for Taq-I (OR = 2.58, 95% CI 1.51-4.40) were susceptibility genotypes for MS. Apa-I and Bsm-I were not significantly associated with risk of MS (OR < 1, P > 0.05) and any genotypes in any genetic models were not significantly different between cases and controls (P > 0.05). CONCLUSION: As a result, Fok-I and Taq-I showed significant association with risk of MS, while Apa-I and Bsm-I were not observed to be related to the risk of the disease in this population.

POSTOPERATIVE PAIN: MANAGEMENT AND DOCUMENTATION BY IRANIAN NURSES.

BACKGROUND: Pain is one of the most common symptoms experienced by patients after surgeries. Inadequate postoperative pain management is an international problem and the need to improve its management is well documented. The aim of the study was to assess nursing reports related to the patients' pain intensity and quality, concomitant symptoms, use of scales in pain assessment, and compliance with the national guideline after surgery. METHODS: This study was a retrospective cohort; samples were nurse records of patients who had elective surgery. RESULT: Only 6% of the patients' pain records included pain intensity which was not measured with standard scales. More than half of all injections were opioid analgesic which is in contrast to the guidelines of the Iranian Ministry of Health. Pain assessment was higher in women and by nurses with more than 15 years of working experience. CONCLUSION: to conclude, the patients' pain was not assessed properly in terms of intensity, quality, and associated symptoms. Therefore, training and motivating nurses is very important in this context and should be incorporated in nurses' academic and continuous educational courses.

THE ASSESSMENT OF CAREGIVER BURDEN IN CAREGIVERS OF HEMODIALYSIS PATIENTS.

BACKGROUND: Chronic renal failure is among the chronic disease which due to persistence of the disease and long treatment process has various effects on the physiological, psychological, functional ability, lifestyle changes, and independence status of the patient and his family. This may result in the burden feeling in caregivers. According to the importance of the subject, this study is to assess the level of caregiver burden in caregivers of hemodialysis patients. METHODS: This is a cross-sectional analytical descriptive study that was conducted in 2014 on the caregivers of hemodialysis patients. Research instruments were consisted of two parts: demographic data check list and caregiver burden questionnaire. Data were analyzed by SPSS statistical software and Pearson correlation coefficient tests. A p value of less than 0.05 was considered statistically significant. RESULTS: In this study, 72.5% of caregivers reported moderate to severe levels of caregiver burden. A significant relationship was observed between gender of the patient with caregiver burden score of (p=0.031) and type of the income with caregiver burden score of (p=0.000). Caregivers of male patients and patients with inadequate income had a higher caregiver burden score. CONCLUSIONS: Our results showed that more than half of the caregivers of hemodialysis patients had moderate to severe levels of caregiver burden, therefore it is worthy that health officials and nurses pay special attention to this issue by communicating with these patients and their caregivers.

Helicobacter pylori in vegetables and salads: genotyping and antimicrobial resistance properties.

From a clinical and epidemiological perspective, it is important to know which genotypes and antibiotic resistance patterns are present in H. pylori strains isolated from salads and vegetables. Therefore, the present investigation was carried out to find this purpose. Three hundred eighty washed and unwashed vegetable samples and fifty commercial and traditional salad samples were collected from Isfahan, Iran. Samples were cultured and those found positive for H. pylori were analyzed using PCR. Antimicrobial susceptibility testing was performed using disk diffusion method. Seven out of 50 (14%) salad and 52 out of 380 (13.68%) vegetable samples harbored H. pylori. In addition, leek, lettuce, and cabbage were the most commonly contaminated samples (30%). The most prevalent virulence genes were oipA (86.44%) and cagA (57.625). VacA s1a (37.28%) and iceA1 (47.45%) were the most prevalent genotypes. Forty different genotypic combinations were recognized. S1a/cagA+/iceA1/oipA+ (33.89%), s1a/cagA+/iceA2/oipA (30.50%), and m1a/cagA+/iceA1/oipA+ (28.81%) were the most prevalent combined genotypes. Bacterial strains had the highest levels of resistance against metronidazole (77.96%), amoxicillin (67.79%), and ampicillin (61.01%). High similarity in the genotyping pattern of H. pylori among vegetable and salad samples and human specimens suggests that vegetable and salads may be the sources of the bacteria.