EXO1 protects BRCA1-deficient cells against toxic DNA lesions.

Inactivating mutations in the BRCA1 and BRCA2 genes impair DNA double-strand break (DSB) repair by homologous recombination (HR), leading to chromosomal instability and cancer. Importantly, BRCA1/2 deficiency also causes therapeutically targetable vulnerabilities. Here, we identify the dependency on the end resection factor EXO1 as a key vulnerability of BRCA1-deficient cells. EXO1 deficiency generates poly(ADP-ribose)-decorated DNA lesions during S phase that associate with unresolved DSBs and genomic instability in BRCA1-deficient but not in wild-type or BRCA2-deficient cells. Our data indicate that BRCA1/EXO1 double-deficient cells accumulate DSBs due to impaired repair by single-strand annealing (SSA) on top of their HR defect. In contrast, BRCA2-deficient cells retain SSA activity in the absence of EXO1 and hence tolerate EXO1 loss. Consistent with a dependency on EXO1-mediated SSA, we find that BRCA1-mutated tumors show elevated EXO1 expression and increased SSA-associated genomic scars compared with BRCA1-proficient tumors. Overall, our findings uncover EXO1 as a promising therapeutic target for BRCA1-deficient tumors.

(Single-stranded DNA) gaps in understanding BRCAness.

The tumour-suppressive roles of BRCA1 and 2 have been attributed to three seemingly distinct functions - homologous recombination, replication fork protection, and single-stranded (ss)DNA gap suppression - and their relative importance is under debate. In this review, we examine the origin and resolution of ssDNA gaps and discuss the recent advances in understanding the role of BRCA1/2 in gap suppression. There are ample data showing that gap accumulation in BRCA1/2-deficient cells is linked to genomic instability and chemosensitivity. However, it remains unclear whether there is a causative role and the function of BRCA1/2 in gap suppression cannot unambiguously be dissected from their other functions. We therefore conclude that the three functions of BRCA1 and 2 are closely intertwined and not mutually exclusive.

Long-Term Impact of Iatrogenic Bile Duct Injury.

BACKGROUND: Bile duct injury (BDI) is a devastating complication following cholecystectomy. After initial management of BDI, patients stay at risk for late complications including anastomotic strictures, recurrent cholangitis, and secondary biliary cirrhosis. METHODS: We provide a comprehensive overview of current literature on the long-term outcome of BDI. Considering the availability of only limited data regarding treatment of anastomotic strictures in literature, we also retrospectively analyzed patients with anastomotic strictures following a hepaticojejunostomy (HJ) from a prospectively maintained database of 836 BDI patients. RESULTS: Although clinical outcomes of endoscopic, radiologic, and surgical treatment of BDI are good with success rates of around 90%, quality of life (QoL) may be impaired even after "clinically successful" treatment. Following surgical treatment, the incidence of anastomotic strictures varies from 5 to 69%, with most studies reporting incidences around 10-20%. The median time to stricture formation varies between 11 and 30 months. Long-term BDI-related mortality varies between 1.8 and 4.6%. Of 91 patients treated in our center for anastomotic strictures after HJ, 81 (89%) were treated by percutaneous balloon dilatation, with a long-term success rate of 77%. Twenty-four patients primarily or secondarily underwent surgical revision, with recurrent strictures occurring in 21%. CONCLUSIONS: The long-term impact of BDI is considerable, both in terms of clinical outcomes and QoL. Treatment should be performed in tertiary expert centers to optimize outcomes. Patients require a long-term follow-up to detect anastomotic strictures. Strictures should initially be managed by percutaneous dilatation, with surgical revision as a next step in treatment.

Percutaneous-endoscopic rendezvous procedure for the management of bile duct injuries after cholecystectomy: short- and long-term outcomes.

BACKGROUND: Bile duct injury (BDI) remains a daunting complication of laparoscopic cholecystectomy. In patients with complex BDI, a percutaneous-endoscopic rendezvous procedure may be required to establish bile duct continuity. The aim of this study was to assess short- and long-term outcomes of the rendezvous procedure. METHODS: All consecutive patients with BDI referred to our tertiary referral center between 1995 and 2016 were analyzed. A rendezvous procedure was performed when endoscopic or radiologic intervention failed, and when deemed feasible by a dedicated multidisciplinary team including hepatopancreaticobiliary surgeons, gastrointestinal endoscopists, and interventional radiologists. Classification of BDI, technical success of the rendezvous procedure, procedure-related adverse events, and outcomes were assessed. RESULTS: Among a total of 812 patients, rendezvous was performed in 47 (6 %), 31 (66 %) of whom were diagnosed with complete transection of the bile duct (Amsterdam type D/Strasberg type E injury). The primary success rate of rendezvous was 94 % (44 /47 patients). Overall morbidity was 18 % (10 /55 procedures). No life-threatening adverse events or 90-day mortality occurred. After a median follow-up of 40 months (interquartile range 23 - 54 months), rendezvous was the final successful treatment in 26 /47 patients (55 %). In 14 /47 patients (30 %), rendezvous acted as a bridge to surgery, with hepaticojejunostomy being chosen either primarily or secondarily to treat refractory or relapsing stenosis. CONCLUSIONS: In experienced hands, rendezvous was a safe procedure, with a long-term success rate of 55 %. When endoscopic or transhepatic interventions fail to restore bile duct continuity in patients with BDI, rendezvous should be considered, either as definitive treatment or as a bridge to elective surgery.

In situ visualization of glucocerebrosidase in human skin tissue: zymography versus activity-based probe labeling.

Epidermal ß-glucocerebrosidase (GBA1), an acid ß-glucosidase normally located in lysosomes, converts (glucosyl)ceramides into ceramides, which is crucial to generate an optimal barrier function of the outermost skin layer, the stratum corneum (SC). Here we report on two developed in situ methods to localize active GBA in human epidermis: i) an optimized zymography method that is less labor intensive and visualizes enzymatic activity with higher resolution than currently reported methods using either substrate 4-methylumbelliferyl-ß-D-glucopyranoside or resorufin-ß-D-glucopyranoside; and ii) a novel technique to visualize active GBA1 molecules by their specific labeling with a fluorescent activity-based probe (ABP), MDW941. The latter method pro-ved to be more robust and sensitive, provided higher resolution microscopic images, and was less prone to sample preparation effects. Moreover, in contrast to the zymography substrates that react with various ß-glucosidases, MDW941 specifically labeled GBA1. We demonstrate that active GBA1 in the epidermis is primarily located in the extracellular lipid matrix at the interface of the viable epidermis and the lower layers of the SC. With ABP-labeling, we observed reduced GBA1 activity in 3D-cultured skin models when supplemented with the reversible inhibitor, isofagomine, irrespective of GBA expression. This inhibition affected the SC ceramide composition: MS analysis revealed an inhibitor-dependent increase in the glucosylceramide:ceramide ratio.

Sphingolipid paracrine signaling impairs keratinocyte adhesion to promote melanoma invasion.

Melanoma is the deadliest form of skin cancer due to its propensity to metastasize. It arises from melanocytes, which are attached to keratinocytes within the basal epidermis. Here, we hypothesize that, in addition to melanocyte-intrinsic modifications, dysregulation of keratinocyte functions could initiate early-stage melanoma cell invasion. We identified the lysolipid sphingosine 1-phosphate (S1P) as a tumor paracrine signal from melanoma cells that modifies the keratinocyte transcriptome and reduces their adhesive properties, leading to tumor invasion. Mechanistically, tumor cell-derived S1P reduced E-cadherin expression in keratinocytes via S1P receptor dependent Snail and Slug activation. All of these effects were blocked by S1P2/3 antagonists. Importantly, we showed that epidermal E-cadherin expression was inversely correlated with the expression of the S1P-producing enzyme in neighboring tumors and the Breslow thickness in patients with early-stage melanoma. These findings support the notion that E-cadherin loss in the epidermis initiates the metastatic cascade in melanoma.

The experiences of family caregivers who participated in a family involvement program after cancer surgery: A qualitative study.

PURPOSE: As recovery time after oncological surgery can be long, family caregivers often play an important role in the delivery of care after patients' discharge. To prepare carers for this role, we developed a family involvement program (FIP) to enhance their active involvement in post-surgical oncology care during hospitalization. The purpose of this qualitative study was to explore family caregivers experience of participating in a FIP. METHODS: We conducted semi-structured interviews with 12 family caregivers who participated in the family involvement program. The program is comprised of two main components (1) training and coaching of physicians and nurses; (2) active involvement of family caregivers in fundamental care activities. This active involvement included six activities. Data were analyzed using interpretative phenomenological analysis. RESULTS: Family caregivers positively valued the program. Active participation in post-surgical care was experienced as an acceptable burden. The program gave participants the ability to simply be present ('being there') which was considered as essential and improved their understanding of care, although family caregivers sometimes experienced emotional moments. Active involvement strengthened existent relationship between the family caregiver and the patient. Participants thought clinical supervision. by nurses is important. CONCLUSIONS: Physical proximity appeared as an essential part of the family involvement program. It helped carers to feel they made a meaningful contribution to their loved ones' wellbeing. Asking families to participate in fundamental care activities in post-surgical oncology care was acceptable, and not over-demanding for caregivers.

Glucosylated cholesterol in skin: Synthetic role of extracellular glucocerebrosidase.

The existence of glucosylated cholesterol (GlcChol) in tissue has recently been recognized. GlcChol is generated from glucosylceramide (GlcCer) and cholesterol through transglucosylation by two retaining ß-glucosidases, GBA and GBA2. Given the abundance of GBA, GlcCer and cholesterol in the skin's stratum corneum (SC), we studied the occurrence of GlcChol. A significant amount of GlcChol was detected in SC (6 pmol/mg weight). The ratio GlcChol/GlcCer is higher in SC than epidermis, 0.083 and 0.011, respectively. Examination of GlcChol in patients with Netherton syndrome revealed comparable levels (11 pmol/mg). Concluding, GlcChol was identified as a novel component in SC and is likely locally metabolized by GBA. The physiological function of GlcChol in the SC warrants future investigation.

Active involvement of family members in postoperative care after esophageal or pancreatic resection: A feasibility study.

BACKGROUND: Active involvement of relatives has the potential to improve postoperative patient outcomes by prevention of complications sensitive to basic care and unplanned readmissions. The aim of this study was to assess the feasibility of a program in which relatives participated in postoperative care. METHODS: A pragmatic feasibility trial conducted at the surgical ward of a University hospital in the Netherlands. Patients undergoing esophageal or pancreatic resection with a relative who was willing and able to participate formed the intervention group (n = 20). A control group (n = 20) received usual postoperative care. The program consisted of the following: (1) information; (2) shared goal setting; (3) task-oriented training; (4) participation in basic care, focusing on mobilization, breathing exercises, cognitive activities and oral hygiene; (5) presence of relatives during ward rounds; and (6) rooming-in. Feasibility criteria were adherence to basic care, caregiver burden, and satisfaction of patients, family, and healthcare professionals. RESULTS: All participants completed the program. Patients in the intervention group mobilized more (estimated difference for walking 170 meters per day, P = .037, and for sitting 109 minutes per day, P < .001), and showed more adherence to breathing exercises (estimated difference per day 1.4, P = .003), oral hygiene (estimated difference 1.52, P = .001), and cognitive activities (estimated difference 2.6, P < .001). Relatives'Care-Related Quality of Life instrument score did not deteriorate over time (P = .64); 96% of relatives would recommend the program and 92% felt better prepared for discharge. Patients in the intervention group were more satisfied with hospital admission. Healthcare professionals valued the program positively. CONCLUSION: This program is feasible and is positively appreciated by patients, family, and healthcare professionals. Patients following the program showed more adherence to basic care activities.

Developing an evidence-based and theory informed intervention to involve families in patients care after surgery: A quality improvement project.

OBJECTIVES: In the post-surgical setting, active involvement of family caregivers has the potential to improve patient outcomes by prevention of surgical complications that are sensitive to fundamental care. This paper describes the development of a theoretically grounded program to enhance the active involvement of family caregivers in fundamental care for post-surgical patients. METHODS: We used a quality improvement project following a multi-phase design. In Phase 1, an iterative method was used to combine evidence from a narrative review and professionals' preferences. In Phase 2, the logic model underlying the program was developed guided by four steps: (1) confirm situation, intervention aim, and target population; (2) documented expected outcomes, and outputs of the intervention; (3) identify and describe assumptions, external factors and inputs; and (4) confirm intervention components. RESULTS: Phase 1 identified a minimum set of family involvement activities that were both supported by staff and the narrative review. In Phase 2, the logic model was developed and includes (1) the inputs (e.g. educational- and environmental support), (2) the ultimate outcomes (e.g. reduction of postoperative complications), (3) the intermediate outcomes (e.g. behavioural changes), and (4) immediate outcomes (e.g. improved knowledge, skills and attitude). CONCLUSIONS: We demonstrated how we aimed to change our practice to an environment in which family caregivers were stimulated to be actively involved in postoperative care on surgical wards, and how we took different factors into account. The description of this program may provide a solid basis for professionals to implement the family involvement program in their own setting.

Morbidity and mortality after major liver resection in patients with perihilar cholangiocarcinoma: A systematic review and meta-analysis.

BACKGROUND: Morbidity and mortality after hepatectomy for perihilar cholangiocarcinoma are known to be high. However, reported postoperative outcomes vary, with notable differences between Western and Asian series. We aimed to determine morbidity and mortality rates after major hepatectomy in patients with perihilar cholangiocarcinoma and assess differences in outcome regarding geographic location and hospital volume. METHODS: A systematic review was performed by searching the MEDLINE and EMBASE databases through November 20, 2017. Risk of bias was assessed and meta-analysis and metaregression were performed using a random effects model. RESULTS: A total of 51 studies were included, representing 4,634 patients. Pooled 30-day and 90-day mortality were 5% (95% CI 3%-6%) and 9% (95% CI 6%-12%), respectively. Pooled overall morbidity and severe morbidity were 57% (95% CI 50%-64%) and 40% (95% CI 34%-47%), respectively. Western studies compared with Asian studies had a significantly higher 30-day mortality, 90-day mortality, and overall morbidity: 8% versus 2% (P < .001), 12% versus 3% (P < .001), and 63% versus 54% (P = .048), respectively. This effect on mortality remained significant after correcting for hospital volume. Univariate metaregression analysis showed no influence of hospital volume on mortality or morbidity, but when corrected for geographic location, higher hospital volume was associated with higher severe morbidity (P = .039). CONCLUSION: Morbidity and mortality rates after major hepatectomy for perihilar cholangiocarcinoma are high. The Western series showed a higher mortality compared with the Asian series, even when corrected for hospital volume. Standardized reporting of outcomes is necessary. Underlying causes for differences in outcomes between Asian and Western centers, such as differences in treatment strategies, should be further analyzed.

Intrabiliary Migrated Clips and Coils as a Nidus for Biliary Stone Formation: A Rare Complication following Laparoscopic Cholecystectomy.

Clips inserted during laparoscopic cholecystectomy (LC) may migrate into the biliary system and function as a nidus for the formation of gallstones. Here, we present a series of 4 patients who presented with this rare complication 5-17 years after LC. All 4 patients presented with symptomatic choledocholithiasis with biochemical and radiological signs of biliary obstruction. Three patients also had fever and infectious parameters, compatible with concurrent cholangitis. All patients successfully underwent endoscopic retrograde cholangiopancreatography (ERCP) with papillotomy and stone extraction. Patients with cholangitis also had antibiotic treatment. In 3 patients, obstruction of the common bile duct was caused by a single, relatively large stone that had formed around a clip (supposedly the cystic duct clip). In 1 patient, multiple stones had formed around an intrabiliary migrated cluster of coils that had been used for arterial embolization of a pseudo-aneurysm of the right hepatic artery. In conclusion, surgical clips and coils can migrate into the biliary tract and serve as a nidus for the formation of bile duct stones. Although rare, this complication should caution surgeons not to place clips "at random" during cholecystectomy. Patients with this rare complication are best managed by ERCP in combination with sphincterotomy and stone extraction.