Abed Khalaileh

Systemic Regulation of the Age-Related Decline of Pancreatic β-Cell Replication

The frequency of pancreatic β-cell replication declines dramatically with age, potentially contributing to the increased risk of type 2 diabetes in old age. Previous studies have shown the involvement of cell-autonomous factors in this phenomenon, particularly the decline of polycomb genes and accumulation of p16/INK4A. Here, we demonstrate that a systemic factor found in the circulation of young mice is able to increase the proliferation rate of old pancreatic β-cells. Old mice parabiosed to young mice have increased β-cell replication compared with unjoined old mice or old mice parabiosed to old mice. In addition, we demonstrate that old β-cells transplanted into young recipients have increased replication rate compared with cells transplanted into old recipients; conversely, young β-cells transplanted into old mice decrease their replication rate compared with young cells transplanted into young recipients. The expression of p16/INK4A mRNA did not change in heterochronic parabiosis, suggesting the involvement of other pathways. We conclude that systemic factors contribute to the replicative decline of old pancreatic β-cells.

Role of the ductal transcription factors HNF6 and Sox9 in pancreatic acinar-to-ductal metaplasia

Objective Growing evidence suggests that a phenotypic switch converting pancreatic acinar cells to duct-like cells can lead to pancreatic intraepithelial neoplasia and eventually to invasive pancreatic ductal adenocarcinoma. Histologically, the onset of this switch is characterised by the co-expression of acinar and ductal markers in acini, a lesion called acinar-to-ductal metaplasia (ADM). The transcriptional regulators required to initiate ADM are unknown, but need to be identified to characterise the regulatory networks that drive ADM. In this study, the role of the ductal transcription factors hepatocyte nuclear factor 6 (HNF6, also known as Onecut1) and SRY-related HMG box factor 9 (Sox9) in ADM was investigated. Design Expression of HNF6 and Sox9 was measured by immunostaining in normal and diseased human pancreas. The function of the factors was tested in cultured cells and in mouse models of ADM by a combination of gain and loss of function experiments. Results Expression of HNF6 and Sox9 was ectopically induced in acinar cells in human ADM as well as in mouse models of ADM. HNF6 and, to a lesser extent, Sox9 were required for repression of acinar genes, for modulation of ADM-associated changes in cell polarity and for activation of ductal genes in metaplastic acinar cells. Conclusions HNF6 and Sox9 are new biomarkers of ADM and constitute candidate targets for preventive treatment in cases when ADM may lead to cancer. This work also shows that ectopic activation of transcription factors may underlie metaplastic processes occurring in other organs.

Single-incision laparoscopic cholecystectomy: lessons learned for success.

Since its introduction approximately 20 years ago, laparoscopic cholecystectomy has rapidly become the treatment of choice for symptomatic cholelithiasis [1–3]. Conventional laparoscopic cholecystectomy generally is performed through four small incisions in the abdominal wall [4]. In recent years, a less invasive method has been sought in an effort to reduce postoperative pain and morbidities such as wound infection and trocar-site hernias while further enhancing the cosmetic results. Initial attempts to perform the procedure through three and then two ports or with reduced-diameter trocars (needlescopic surgery) [5–9] have since been superseded by even less invasive and more innovative techniques, namely, single-incision laparoscopic surgery (SILS) and natural orifice transluminal endoscopic surgery (NOTES) [10–13]. Single-incision laparoscopic surgery is an attractive technique for cholecystectomy due to its superior cosmetic results and potential to reduce the rate of wound complications such as infection, hematoma, and hernia. This technique, however, is not straightforward. The technical complexity of SILS naturally results in a steep learning curve and increased operating room time and requires specialized equipment. The primary technical obstacles of SILS currently include Collision of instruments both within and outside the abdomen as a result of their common entry point (“sword fighting”) Inadequate triangulation Compromised field of view due to obstruction by instruments entering the common port Inadequate exposure and retraction. Several techniques have since evolved to overcome these potential pitfalls [14–16]. By incorporating a number of these techniques, we have created a simplified technique that has proved successful with both animal and human subjects. We describe both our experience and what we have learned, which have allowed simplification of a technical complex procedure.

Providing more through less: current methods of retraction in SIMIS and NOTES cholecystectomy

BackgroundAs the field of minimally invasive surgery continues to develop, surgeons are confronted with the challenge of performing conventional laparoscopic surgeries through fewer incisions while maintaining the same degree of safety and surgical efficiency. Most of these methods involve elimination of the ports previously designated for retraction. As a result, minimally invasive surgeons have been forced to develop minimally invasive and ingenious methods for providing adequate retraction for these procedures. Herein we present our experience using endoloops and internal retractors to provide retraction during Single Incision Minimally Invasive Surgery (SIMIS) and Natural Orifice Transluminal Endoscopic Surgery (NOTES) cholecystectomy. We also present a review of the alternative retraction methods currently being employed for these surgeries.MethodsSIMIS was performed on 20 patients and NOTES was performed on 5 patients at our institution. Endoloops or internal retractors were used to provide retraction for all SIMIS procedures. Internal retractors provided retraction for all NOTES procedures.ResultsSuccessful cholecystectomy was accomplished in all cases. One SIMIS surgery required conversion to standard laparoscopy due to complex anatomy. There were no intraoperative complications. Although adequate retraction was accomplished in all cases, the internal retractors were found to provide superior and more versatile retraction compared to that of endoloops.ConclusionAdequate retraction greatly simplifies SIMIS and NOTES surgery. Endograb internal retractors were easy to use and were found to provide optimal retraction and exposure during these procedures without complications.

Phosphorylation of ribosomal protein S6 attenuates DNA damage and tumor suppression during development of pancreatic cancer

The signaling pathways that mediate the development of pancreatic ductal adenocarcinoma (PDAC) downstream of mutant Kras remain incompletely understood. Here, we focus on ribosomal protein S6 (rpS6), an mTOR effector not implicated previously in cancer. Phosphorylation of rpS6 was increased in pancreatic acinar cells upon implantation of the chemical carcinogen 7,12-dimethylbenz(a)anthracene (DMBA) or transgenic expression of mutant Kras. To examine the functional significance of rpS6 phosphorylation, we used knockin mice lacking all five phosphorylatable sites in rpS6 (termed rpS6(P-/-) mice). Strikingly, the development of pancreatic cancer precursor lesions induced by either DMBA or mutant Kras was greatly reduced in rpS6(P-/-) mice. The rpS6 mutants expressing oncogenic Kras showed increased p53 along with increased staining of γ-H2AX and 53bp1 (Trp53bp1) in areas of acinar ductal metaplasia, suggesting that rpS6 phosphorylation attenuates Kras-induced DNA damage and p53-mediated tumor suppression. These results reveal that rpS6 phosphorylation is important for the initiation of pancreatic cancer.

Distinct Murine Mucosal Langerhans Cell Subsets Develop from Pre-dendritic Cells and Monocytes.

Langerhans cells (LCs) populate the mucosal epithelium, a major entry portal for pathogens, yet their ontogeny remains unclear. We found that, in contrast to skin LCs originating from self-renewing radioresistant embryonic precursors, oral mucosal LCs derive from circulating radiosensitive precursors. Mucosal LCs can be segregated into CD103(+)CD11b(lo) (CD103(+)) and CD11b(+)CD103(-) (CD11b(+)) subsets. We further demonstrated that similar to non-lymphoid dendritic cells (DCs), CD103(+) LCs originate from pre-DCs, whereas CD11b(+) LCs differentiate from both pre-DCs and monocytic precursors. Despite this ontogenetic discrepancy between skin and mucosal LCs, the transcriptomic signature and immunological function of oral LCs highly resemble those of skin LCs but not DCs. These findings, along with the epithelial position, morphology, and expression of the LC-associated phenotype strongly suggest that oral mucosal LCs are genuine LCs. Collectively, in a tissue-dependent manner, murine LCs differentiate from at least three distinct precursors (embryonic, pre-DC, and monocytic) in steady state.

Nutritional deficiencies after sleeve gastrectomy: can they be predicted preoperatively?

BACKGROUND Nutritional deficiencies are common among morbidly obese patients. Data are scarce for patients who have undergone laparoscopic sleeve gastrectomy (LSG). OBJECTIVES The aim of the study is to clarify the prevalence of deficiencies and to identify risk factors for postoperative deficiencies. SETTINGS Hebrew University, Israel. METHODS Preoperative and 1-year postoperative data were collected. We included anthropometric parameters, obesity-related co-morbidities, and laboratory findings. RESULTS There were 192 candidates. Seventy-seven of them completed follow-ups at 12 months. Before surgery, 15% had anemia. Deficiencies of iron, folate, and B12 were 47%, 32%, and 13%, respectively. Women were more deficient in iron (56% women, 26% men, P<.001). Before surgery, low levels of vitamin D and elevated parathyroid hormone (PTH) were 99% and 41%, respectively. One year postsurgery, the deficiencies of hemoglobin and vitamin B12 worsened (20% and 17%, P<.001, P = .048, respectively). One year postsurgery, deficiencies of iron, folate, vitamin D, and PTH improved (28%, 21%, 94%, and 10%, respectively). Deficiencies of hemoglobin, folate, and B12 before surgery were predictors for deficiencies 1 year after surgery (P = .006 OR = .090; P = .012 OR = .069; P = .062 OR = .165, respectively). CONCLUSIONS LSG had a modest effect on nutritional deficiencies in our patients at 1-year postsurgery. Focusing on the preoperative nutritional status and tailoring a specific supplemental program for each individual should prevent postoperative deficiencies.

Short-term overexpression of VEGF-A in mouse beta cells indirectly stimulates their proliferation and protects against diabetes

Aims/hypothesisVascular endothelial growth factor (VEGF) has been recognised by loss-of-function experiments as a pleiotropic factor with importance in embryonic pancreas development and postnatal beta cell function. Chronic, non-conditional overexpression of VEGF-A has a deleterious effect on beta cell development and function. We report, for the first time, a conditional gain-of-function study to evaluate the effect of transient VEGF-A overexpression by adult pancreatic beta cells on islet vasculature and beta cell proliferation and survival, under both normal physiological and injury conditions.MethodsIn a transgenic mouse strain, overexpressing VEGF-A in a doxycycline-inducible and beta cell-specific manner, we evaluated the ability of VEGF-A to affect islet vessel density, beta cell proliferation and protection of the adult beta cell mass from toxin-induced injury.ResultsShort-term VEGF-A overexpression resulted in islet hypervascularisation, increased beta cell proliferation and protection from toxin-mediated beta cell death, and thereby prevented the development of hyperglycaemia. Extended overexpression of VEGF-A led to impaired glucose tolerance, elevated fasting glycaemia and a decreased beta cell mass.Conclusions/interpretationOverexpression of VEGF-A in beta cells time-dependently affects glycometabolic control and beta cell protection and proliferation. These data nourish further studies to examine the role of controlled VEGF delivery in (pre)clinical applications aimed at protecting and/or restoring the injured beta cell mass.

Malignant Appendiceal GIST: Case Report and Review of the Literature

IntroductionGastro-intestinal stromal tumors (GISTs) of the appendix are a rare entity. To date, only a handful has been described in the literature, all of which have been of the benign type.Case ReportWe present the first reported case of a malignant appendiceal GIST. The tumor was discovered when the patient presented with a peri-appendiceal abscess which appeared suspicious on CT. The abscess was drained and managed medically. The patient responded to antibiotic treatment but subsequent CT and biopsy confirmed the diagnosis of appendiceal GIST, and the patient was started on treatment with imatinab mesylate.DiscussionOne week after initiation of therapy, the patient returned with frank peritonitis necessitating surgery. Abdominal exploration revealed an appendiceal GIST locally invading and perforating adjacent bowel. We describe the complex presentation and course of the case as well as a literature review of the appendiceal GISTs and the current approach to treatment.

Sleeve gastrectomy and mesenteric venous thrombosis: report of 3 patients and review of the literature

haim Mesenteric venous thrombosis (MVT) is a rare but potentially lethal pathology. Although first described by Balfour and Stewart in 1869 [1], it was first presented as a distinct cause of mesenteric ischemia by Warren and Eberhand only in 1935 [2]. MVT accounts for 5%–15% of all mesenteric ischemic events [2,3]. In the past, MVT has been described after procedures involving manipulation of the portal venous system, such as splenectomy or liver transplantation [4,5]. However, since the beginning of the minimal invasive era, MVT has occurred in several cases after various laparoscopic procedures [6]. During the last decade, a few cases of MVT have been published to occur after laparoscopic bariatric operations, including laparoscopic sleeve gastrectomy (LSG) [7]. Nevertheless, MVT has been shown to be a major morbidity during the perioperative period of LSG with an incidence of 1% [8]. The aim of this article is to present 3 cases of MVT that have occurred after 900 LSG procedures in our center, discuss the pathophysiology and management of this complication and suggest preventive strategy.