RAD51 foci as a functional biomarker of homologous recombination repair and PARP inhibitor resistance in germline BRCA-mutated breast cancer.

Background: BRCA1 and BRCA2 (BRCA1/2)-deficient tumors display impaired homologous recombination repair (HRR) and enhanced sensitivity to DNA damaging agents or to poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi). Their efficacy in germline BRCA1/2 (gBRCA1/2)-mutated metastatic breast cancers has been recently confirmed in clinical trials. Numerous mechanisms of PARPi resistance have been described, whose clinical relevance in gBRCA-mutated breast cancer is unknown. This highlights the need to identify functional biomarkers to better predict PARPi sensitivity. Patients and methods: We investigated the in vivo mechanisms of PARPi resistance in gBRCA1 patient-derived tumor xenografts (PDXs) exhibiting differential response to PARPi. Analysis included exome sequencing and immunostaining of DNA damage response proteins to functionally evaluate HRR. Findings were validated in a retrospective sample set from gBRCA1/2-cancer patients treated with PARPi. Results: RAD51 nuclear foci, a surrogate marker of HRR functionality, were the only common feature in PDX and patient samples with primary or acquired PARPi resistance. Consistently, low RAD51 was associated with objective response to PARPi. Evaluation of the RAD51 biomarker in untreated tumors was feasible due to endogenous DNA damage. In PARPi-resistant gBRCA1 PDXs, genetic analysis found no in-frame secondary mutations, but BRCA1 hypomorphic proteins in 60% of the models, TP53BP1-loss in 20% and RAD51-amplification in one sample, none mutually exclusive. Conversely, one of three PARPi-resistant gBRCA2 tumors displayed BRCA2 restoration by exome sequencing. In PDXs, PARPi resistance could be reverted upon combination of a PARPi with an ataxia-telangiectasia mutated (ATM) inhibitor. Conclusion: Detection of RAD51 foci in gBRCA tumors correlates with PARPi resistance regardless of the underlying mechanism restoring HRR function. This is a promising biomarker to be used in the clinic to better select patients for PARPi therapy. Our study also supports the clinical development of PARPi combinations such as those with ATM inhibitors.

Radiographers' perceptions of first year diagnostic radiography students' performance following implementation of a simulation-based education model.

INTRODUCTION: Simulation-based education (SBE) partially replaced the clinical placement learning for a cohort of first year students on a BSc (Hons) Diagnostic Radiography programme. This was in response to the pressures on hospital-based training caused by increasing student numbers and following increased capability and positive outcomes for student learning in delivering SBE as a result of the COVID-19 pandemic. METHODS: A survey was distributed to diagnostic radiographers, across five NHS Trusts, involved in the clinical education of first year diagnostic radiography students at one UK university. The survey sought radiographers' perception of student performance in undertaking radiographic examinations, safety procedures, knowledge of anatomy, professionalism, and the impact of embedding simulation-based education through multichoice and free text questions. Descriptive and thematic analysis of the survey data was undertaken. RESULTS: Twelve survey responses from radiographers across four Trusts were collated. Responses indicated the majority of radiographers perceived students to require the expected level of assistance in undertaking appendicular examinations, applying infection control and radiation safety measures, and had the expected level of radiographic anatomy knowledge. Students also interacted appropriately with service users, demonstrated increased confidence in coming into the clinical environment and were receptive to feedback. Some variation was noted, particularly in professionalism and engagement, though not always attributed to SBE. CONCLUSION: Replacement of clinical placement with SBE was perceived to have provided appropriate learning opportunities and some additional benefits, however it was felt by some radiographers that SBE could not replace the experience of the real imaging environment. IMPLICATIONS FOR PRACTICE: Embedding simulated-based education requires a holistic approach and close collaboration with placement partners to ensure complimentary learning experiences in the clinical placement setting, and support achievement of the learning outcomes.

Characteristics of AZD9708, a novel, selective ß2-adrenoceptor agonist with rapid onset and long duration of action.

Here we describe the pre-clinical pharmacological profile of AZD9708, a novel long-acting ß(2)-adrenoceptor agonist that has potential as a once-daily therapy for asthma and chronic obstructive pulmonary disease (COPD). AZD9708 is a potent and selective agonist at the human ß(2)-adrenoceptor, with selectivity over human ß(1)- and ß(3)-adrenoceptors of >500 and >24 fold, respectively. AZD9708 relaxes carbachol-induced contraction of human bronchial rings with a time to 90% of maximal relaxation of 13-20 min, similar to that seen with formoterol and quicker than salmeterol. In anesthetized guinea pigs, AZD9708 provides significant protection against histamine-induced airway constriction at 24 h after intratracheal and nebulized doses. This is longer than with intratracheal salmeterol, which is bronchoprotective for approximately 8 h, and formoterol, which is bronchoprotective for 8 and 12 h following nebulized and intratracheal dosing, respectively. AZD9708 also shows the potential for a greater therapeutic margin than widely used ß(2)-adrenoceptor agonists such as formoterol. At a defined efficacy dose that provides 80% bronchoprotection (ED(80)), formoterol leads to a decrease in blood potassium levels in guinea pigs, whilst AZD9708 is not associated with significant reductions in potassium levels at doses up to 7 times the ED(80). [(14)C]AZD9708 is associated with extensive protein binding in both human (mean 1.0% free) and rat (mean 2.6% free) plasma. This pharmacological profile indicates the potential of AZD9708 to become an important addition to the range of bronchodilators available for the treatment of patients with obstructive airways disease.

Host inflammatory response profiling in preeclampsia using an in vitro whole blood stimulation model.

The pathophysiology of preeclampsia (PET) implicates an inflammatory dysfunction. This study profiled this host response by challenging whole blood with lipopolysaccharide. Multiplex immunoassays determined interleukin (IL)-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12(p70), IL-13, IL-17, granulocyte/granulocyte macrophage-colony stimulating factors (G-CSF/GM-SCF), interferon(IFN)-gamma, monocyte chemotactic protein (MCP)-1, macrophage inflammatory protein-1beta and tumor necrosis factor (TNF)-alpha levels. Secretory capacity was expressed in pg/million white cells or monocytes (+/-SEM). PET featured significantly higher IL-1beta, IL-2, IL-10, IL-13, G-CSF, IFN-gamma, MCP-1 and TNF-alpha monocyte secretory capacities (p < 0.05). The PET group exhibited an inflammatory hyper-responsiveness (p < 0.01) which was poorly described by the traditional Th1:Th2 dichotomy.

Chronic airway infection leads to angiogenesis in the pulmonary circulation.

In both pulmonary and systemic hypertension, the walls of the arteriolar vessels are thickened and the lumen size is reduced, leading to increased total vascular resistance. It has been reported previously that chronic airway infection and inflammation lead to increased wall thickness in the pulmonary vasculature, without the development of pulmonary hypertension. The aim of the present study was to examine quantitatively the remodeling of intra-acinar blood vessels in chronically infected rat lungs. Adult rats were anesthetized and inoculated intratracheally with Pseudomonas aeruginosa (n = 10) incorporated into agar beads to induce chronic airway infection. Control groups included rats inoculated with sterile agar beads (n = 8) and rats that were not inoculated (n = 6). Chronic infection caused vascular wall thickening without reduction in mean lumen radius. Furthermore, chronic infection led to increased total length of intra-acinar vessels and increased numbers of branch points, demonstrating that angiogenesis had occurred. Preservation of lumen size and formation of new parallel pathways in the vasculature of chronically infected lungs account for the maintenance of normal PVR despite vessel wall remodeling.

Oesophageal ulceration due to slow-release potassium in the presence of left atrial enlargement.

Ulceration of the oesophagus was suspected clinically and confirmed radiologically in a patient with an enlarged left atrium while on treatment with slow release potassium chloride. Its discontinuation resulted in resolution of symptoms. This potentially serious complication of treatment should be considered in patients with enlargement of the left atrium who develop dysphagia. It is avoided by using soluble forms of potassium chloride replacement.

Chronic hypercapnia inhibits hypoxic pulmonary vascular remodeling.

Chronic hypercapnia is commonly found in patients with severe hypoxic lung disease and is associated with a greater elevation of pulmonary arterial pressure than that due to hypoxia alone. We hypothesized that hypercapnia worsens hypoxic pulmonary hypertension by augmenting pulmonary vascular remodeling and hypoxic pulmonary vasoconstriction (HPV). Rats were exposed to chronic hypoxia [inspiratory O(2) fraction (FI(O(2))) = 0.10], chronic hypercapnia (inspiratory CO(2) fraction = 0.10), hypoxia-hypercapnia (FI(O(2)) = 0.10, inspiratory CO(2) fraction = 0.10), or room air. After 1 and 3 wk of exposure, muscularization of resistance blood vessels and hypoxia-induced hematocrit elevation were significantly inhibited in hypoxia-hypercapnia compared with hypoxia alone (P < 0.001, ANOVA). Right ventricular hypertrophy was reduced in hypoxia-hypercapnia compared with hypoxia at 3 wk (P < 0.001, ANOVA). In isolated, ventilated, blood-perfused lungs, basal pulmonary arterial pressure after 1 wk of exposure to hypoxia (20.1 +/- 1.8 mmHg) was significantly (P < 0.01, ANOVA) elevated compared with control conditions (12.1 +/- 0.1 mmHg) but was not altered in hypoxia-hypercapnia (13.5 +/- 0.9 mmHg) or hypercapnia (11.8 +/- 1.3 mmHg). HPV (FI(O(2)) = 0.03) was attenuated in hypoxia, hypoxia-hypercapnia, and hypercapnia compared with control (P < 0.05, ANOVA). Addition of N(omega)-nitro-L-arginine methyl ester (10(-4) M), which augmented HPV in control, hypoxia, and hypercapnia, significantly reduced HPV in hypoxia-hypercapnia. Chronic hypoxia caused impaired endothelium-dependent relaxation in isolated pulmonary arteries, but coexistent hypercapnia partially protected against this effect. These findings suggest that coexistent hypercapnia inhibits hypoxia-induced pulmonary vascular remodeling and right ventricular hypertrophy, reduces HPV, and protects against hypoxia-induced impairment of endothelial function.

Enhanced expression of inducible nitric oxide synthase without vasodilator effect in chronically infected lungs.

We hypothesized that abnormal ventilation-perfusion matching in chronically infected lungs was in part due to excess nitric oxide (NO) production after upregulation of inducible NO synthase (iNOS) expression. Rats were anesthetized and inoculated intratracheally with Pseudomonas aeruginosa incorporated into agar beads (chronically infected) or with sterile agar beads (placebo inoculated) and killed 10-15 days later. Immunohistochemistry demonstrated increased expression of iNOS and reduced expression of endothelial NOS (eNOS) in chronically infected compared with placebo-inoculated or noninoculated lungs. In isolated lungs from chronically infected rats, NOS inhibition with N(omega)-nitro-L-arginine methyl ester increased the mean perfusion pressure (14.4 +/- 2.7 mmHg) significantly more than in the placebo-inoculated (4.8 +/- 1.0 mmHg) or noninoculated (5.3 +/- 0.8 mmHg) lungs (P < 0.01). Although the chronically infected lungs were more sensitive to NOS inhibition, further evidence suggested that the increased iNOS expression was not associated with enhanced iNOS activity. Selective inhibitors of iNOS did not produce an increase in vascular resistance similar to that produced by nonselective inhibitors. Accumulation of nitrate/nitrite in the perfusate of isolated lungs was unchanged by chronic infection. Thus although iNOS expression was increased in chronic pulmonary infection, iNOS activity in the intact lung was not. Nonetheless, endogenous NO production was essential to maintain normal vascular resistance in these lungs.