Targeting BRCA1‐BER deficient breast cancer by ATM or DNA‐PKcs blockade either alone or in combination with cisplatin for personalized therapy

BRCA1, a key factor in homologous recombination (HR) repair may also regulate base excision repair (BER). Targeting BRCA1‐BER deficient cells by blockade of ATM and DNA‐PKcs could be a promising strategy in breast cancer. We investigated BRCA1, XRCC1 and pol β protein expression in two cohorts (n = 1602 sporadic and n = 50 germ‐line BRCA1 mutated) and mRNA expression in two cohorts (n = 1952 and n = 249). Artificial neural network analysis for BRCA1‐DNA repair interacting genes was conducted in 249 tumours. Pre‐clinically, BRCA1 proficient and deficient cells were DNA repair expression profiled and evaluated for synthetic lethality using ATM and DNA‐PKcs inhibitors either alone or in combination with cisplatin. In human tumours, BRCA1 negativity was strongly associated with low XRCC1, and low pol β at mRNA and protein levels (p < 0.0001). In patients with BRCA1 negative tumours, low XRCC1 or low pol β expression was significantly associated with poor survival in univariate and multivariate analysis compared to high XRCC1 or high pol β expressing BRCA1 negative tumours (ps < 0.05). Pre‐clinically, BRCA1 negative cancer cells exhibit low mRNA and low protein expression of XRCC1 and pol β. BRCA1‐BER deficient cells were sensitive to ATM and DNA‐PKcs inhibitor treatment either alone or in combination with cisplatin and synthetic lethality was evidenced by DNA double strand breaks accumulation, cell cycle arrest and apoptosis. We conclude that XRCC1 and pol β expression status in BRCA1 negative tumours may have prognostic significance. BRCA1‐BER deficient cells could be targeted by ATM or DNA‐PKcs inhibitors for personalized therapy.     

Clinicopathological features of resected pediatric congenital lung and mediastinal lesions: A single institution experience

Objectives:To evaluate resected congenital lung and mediastinal lesions among children and their characteristics in a single tertiary hospital.Methods:A retrospective chart review analysis of all patients under 14 years of age who underwent congenital lung and mediastinal lesion resection in a single tertiary center from June 1997 to June 2018 was performed.Results:In total, 108 cases of resected lung and mediastinal lesions were performed from June 1997 to June 2018. Congenital lung and mediastinal lesions were found in 52 (48%) cases. Overall, 23 cases were males (44%) and 29 (56%) were females. The most common histopathology was congenital lobar emphysema.Conclusion:This study provides a 21-year review of the clinical and histopathological features of resected congenital lung and mediastinal lesions in a single center. Congenital lung and mediastinal lesions represented 48% of all resected lesions.     

Views,experiences and contributory factors related to medication errors associated with direct oral anticoagulants: a qualitative study with physicians and nurses

Background

Direct oral anticoagulants (DOACs) have become preferable for the management of thromboembolic events. Recent publications have however identified high volume of medication errors related to DOACs. There is limited literature on why and how such errors occur or happen in clinical practice.

Aim

This study aimed to explore views, experiences, contributory factors related to DOACs medication errors from the perspectives of healthcare professionals.

Method

Semi-structured interviews using online videoconferencing were conducted with physicians and nurses from tertiary care hospitals in three different regions in Saudi Arabia. Questions included views, experiences and perceived factors contributing to errors. Interviews were transcribed verbatim and were thematically analyzed using MAXQDA Analytics Pro 2020 (VERBI Software).

Results

The semi-structured interviews (n?=?34) included physicians (n?=?20) and nurses (n?=?14) until data saturation was achieved. The analysis identified five themes: Factors related to healthcare professionals (e.g. knowledge, confidence and access to guidelines); Factors related to patients (e.g. comorbidity, polypharmacy, medication review, and communication barriers); Factors related to organization (e.g. guidelines, safety culture and incidents reporting system); Factors related to the DOACs medications (e.g. lack of availability of antidotes and dosing issues); and Strategies for error prevention/mitigation (e.g. the need for professional training and routine medication review).

Conclusion

Healthcare professionals identified errors in relation to DOACs as multifactorial including their own and patient lack of knowledge, lack of clinical guidelines and organizational factors including safety culture. Medication review and reconciliation on discharge were key strategies suggested to reduce DOACs related errors. These strategies support the role of pharmacists as direct patients care providers to minimize DOACs errors.

     

Neuroprotective effect of carnosine and cyclosporine-A against inflammation,apoptosis, and oxidative brain damage after closed head injury in immature rats

Context: Traumatic brain injury in the pediatric population can have a great economic and emotional impact on both the child's family and society.

Objective: The present study aimed to compare the effects of carnosine (CAR) and/or cyclosporine A (CyA) on oxidative brain damage after closed head injury (CHI) in immature rats.

Materials and methods: Thirty-day-old rat pups were divided into five groups: non-traumatic control group, trauma group underwent CHI, trauma group injected with CAR (200?mg/kg, i.p.) following CHI for 7?d, trauma group injected with CyA (20?mg/kg, i.p.) given 15?min and 24?h after CHI, and trauma group treated with CAR and CyA. At the end of the treatment, rats were sacrificed; blood and brains were collected for assessing different biochemical parameters.

Results: Trauma significantly increased brain level of malondialdehyde, nitric oxide, glucose, calcium, inflammatory mediators. Brain DNA damage was confirmed by comet assay and the significant increase in brain caspase-3 activity. Moreover, the serum level of Fas ligand in traumatized animals was significantly elevated. Concomitant decrease in brain-reduced glutathione (GSH) and calcium-adenosine triphosphatase activity was observed in the traumatized-untreated group. Treatment of traumatized animals with CAR and/or CyA ameliorated all the biochemical changes induced by CHI with marked protective effect in the combination group.

Discussion and conclusion: CAR and CyA exerted a synergistic neuroprotective effect against CHI through blocking the induction of lipid peroxidation, reducing inflammatory, and oxidative stress biomarkers, preserving brain GSH content, and reducing the alterations in brain apoptotic biomarkers in traumatized animals.     

Protective effects of combined therapy of gliclazide with curcumin in experimental diabetic neuropathy in rats

Diabetic neuropathy is the most common chronic complication of diabetes. The aim of the present study was to evaluate the protective effects of curcumin against neuropathy in gliclazide-treated diabetic rats. Diabetes was induced by an intraperitoneal injection of streptozotocin (45 mg/kg). Diabetic animals were given gliclazide (10 mg/kg, orally) alone or combined with curcumin (100 mg/kg, orally) or gabapentin (30 mg/kg, intraperitoneally as a positive control). Behavioral responses to thermal (hot plate and tail flick) and mechanical (tail pinch) pain, and some biochemical tests (serum glucose, C-peptide, peroxynitrite, lipid peroxides, and tumor necrosis factor-α) were assessed after 5 consecutive weeks of daily treatment. Combined treatment of curcumin with gliclazide significantly increased hot-plate and tail-flick latencies in comparison with that of the diabetic control group. The threshold of mechanical hyperalgesia was also significantly elevated. Serum glucose and C-peptide levels were significantly increased in the combined treatment compared with the diabetic control group, whereas serum levels of peroxynitrite, lipid peroxide, and tumor necrosis factor-α production were significantly decreased. The data suggest that the combination of curcumin with gliclazide may protect against the development of diabetic neuropathy, with favorable effects with respect to the gliclazide/gabapentin combination.     

Examining anxiety and stress regarding virtual learning in colleges of health sciences: A cross-sectional study in the era of the COVID-19 pandemic in Saudi Arabia

BackgroundStress and anxiety are relatively common, particularly in females and college students. Stress can impact students’ overall performance and their physical and mental health. The COVID-19 pandemic has affected all aspects of life and is associated with high levels of psychological distress. It has considerably affected the education sector, not only locally but worldwide, forcing a shift in the education system from on-site to virtual learning. This cross-sectional study was undertaken to evaluate the prevalence of anxiety and stress regarding virtual learning among health sciences college students in the Kingdom of Saudi Arabia (KSA) after introducing blended virtual classes and exams and in-person laboratory training. The study was carried six months after the COVID-19 outbreak.MethodologyParticipants were recruited by convenient sampling and snowballing strategies. Our study was conducted between November 18 and December 6, 2020. Questionnaires were employed; they included the General Anxiety Disorder-7 (GAD-7) scale and focused on the participants’ attitudes toward virtual learning. The present research was validated by a pilot study, followed by implementing some amendments.ResultsA total of 418 health sciences college students, aged 18–27 (M = 20.88, SD = 1.97), participated in the study. Our analysis indicated that more than half the sample (51.44%) reported a risk of moderate to severe GAD. Anxiety was recognized more frequently in women (72.09%) than in men (27.91%). Interestingly, our Χ² analysis revealed an association between marital status and anxiety, with a higher risk of GAD found in single people (compared with married). In addition, we found that the risk of anxiety increased in junior students (1st-3rd year) compared to senior students (4th-6th year).ConclusionOur study highlights the need to establish gender-based tailored mental health support systems that provide preventive measures. The study findings also recommend that institutions develop programs and platforms that safely support students to interact and seek guidance, particularly those at higher risk of stress, such as females and first-year students. Overall, our study underlines the need to pursue an understanding of the complicated nature of anxiety disorders..     

Lysosomal cathepsin D mediates endogenous mucin glycodomain catabolism in mammals

Mucins are functionally implicated in a range of human pathologies, including cystic fibrosis, influenza, bacterial endocarditis, gut dysbiosis, and cancer. These observations have motivated the study of mucin biosynthesis as well as the development of strategies for inhibition of mucin glycosylation. Mammalian pathways for mucin catabolism, however, have remained underexplored. The canonical view, derived from analysis of N-glycoproteins in human lysosomal storage disorders, is that glycan degradation and proteolysis occur sequentially. Here, we challenge this view by providing genetic and biochemical evidence supporting mammalian proteolysis of heavily O-glycosylated mucin domains without prior deglycosylation. Using activity screening coupled with mass spectrometry, we ascribed mucin-degrading activity in murine liver to the lysosomal protease cathepsin D. Glycoproteomics of substrates digested with purified human liver lysosomal cathepsin D provided direct evidence for proteolysis within densely O-glycosylated domains. Finally, knockout of cathepsin D in a murine model of the human lysosomal storage disorder neuronal ceroid lipofuscinosis 10 resulted in accumulation of mucins in liver-resident macrophages. Our findings imply that mucin-degrading activity is a component of endogenous pathways for glycoprotein catabolism in mammalian tissues.

Mammalian cells append glycans to the majority of their secreted and cell surface proteins (1). These extracellular glycoproteins are broadly categorized as Asn-linked N-glycoproteins and Ser/Thr-linked O-glycoproteins, both of which are typically elaborated into branching structures with many monosaccharide units strung together. Therefore, catabolism of a given extracellular protein typically involves hydrolase-mediated breakdown of both its peptide backbone and one or more complex glycans.Much of our current understanding of glycoprotein catabolism arises from the study of human mutations that cause N-glycoprotein degradation pathways to go awry. Analysis of accumulation products in lysosomal storage disorders such as mannosidosis, aspartylglucosaminuria, sialidosis, Schindler (types I and II), galactosialidosis, and fucosidosis have provided a framework to understand N-glycoprotein catabolism (2). In brief, N-glycoproteins are extensively proteolyzed such that there are free alpha carboxyl and amino groups on the asparagine residue bearing the glycan. After fucose is removed by lysosomal α-L-fucosidase, N-glycanase aspartylglucosaminidase hydrolyzes the glycan-peptide bond. The free glycan can then be broken down from both reducing and nonreducing ends by a variety of hydrolases (2).Lysosomal degradation of O-glycoproteins is understudied relative to that of N-glycoproteins, in part due to unique difficulties associated with structural analysis of O-glycopeptides (3), and is typically assumed to occur analogously to N-glycoprotein catabolism (2, 4). Mucins are a class of extracellular O-glycoproteins that have challenged this assumption. Mucins are characterized by repeating domains bearing a high frequency of N-acetylgalactosamine (GalNAc)-linked serine and threonine residues, such that the biomolecule as a whole can exceed 50% glycosylation by mass (5). The densely spaced glycans in mucin glycodomains endow them with unique properties, including a rigid, extended secondary structure and resistance to proteolysis (6). As such, mucin catabolism has been suggested to proceed in the reverse order of N-glycan catabolism, involving removal of glycans followed by proteolysis of the peptide backbone (2), or through shedding from cell surfaces into luminal spaces (7). Meanwhile, major histocompatibility complex (MHC) I and MHC II peptides bearing mucin-type O-glycans have been repeatedly observed (8–11), indicating that mucin domains can, under some circumstances, be proteolyzed with their glycans intact.We and others have characterized proteases from the bacterial kingdom that cleave within densely O-glycosylated mucin domains without prior deglycosylation, termed mucinases (3, 12–14). The existence of bacterial mucinases indicates that access to the peptide backbone through densely spaced O-glycans is not impossible for a proteolytic enzyme. Given the biological ubiquity and clinical significance of mucins (15–20), we set out to systemically evaluate if mammals encode enzyme(s) with proteolytic activity toward glycosylated mucin domains. At the outset, we considered sequence and structure-based approaches to identify candidates from mammalian genome sequences. However, as bacterial mucinases share poor sequence homology (12, 21), we turned to a biochemical strategy.