Indications and outcomes of enucleation versus formal pancreatectomy for pancreatic neuroendocrine tumors

BackgroundPancreatoduodenectomy (PD) or distal pancreatectomy (DP) are common procedures for patients with a pancreatic neuroendocrine tumor (pNET). Nevertheless, certain patients may benefit from a pancreas-preserving resection such as enucleation (EN). The aim of this study was to define the indications and differences in long-term outcomes among patients undergoing EN and PD/DP.MethodsPatients undergoing resection of a pNET between 1992 and 2016 were identified. Indications and outcomes were evaluated, and propensity score matching (PSM) analysis was performed to compare long-term outcomes between patients who underwent EN versus PD/DP.ResultsAmong 1034 patients, 143 (13.8%) underwent EN, 304 (29.4%) PD, and 587 (56.8%) DP. Indications for EN were small size (1.5 cm, IQR:1.0–1.9), functional tumors (58.0%) that were mainly insulinomas (51.7%). After PSM (n = 109 per group), incidence of postoperative pancreatic fistula (POPF) grade B/C was higher after EN (24.5%) compared with PD/DP (14.0%) (p = 0.049). Median recurrence-free survival (RFS) was comparable among patients who underwent EN (47 months, 95% CI:23–71) versus PD/DP (37 months, 95% CI: 33–47, p = 0.480).ConclusionComparable long-term outcomes were noted among patients who underwent EN versus PD/DP for pNET. The incidence of clinically significant POPF was higher after EN.     

Acquired Glanzmann's thrombasthenia without thrombocytopenia: a severe acquired autoimmune bleeding disorder

Acquired Glanzmann's thrombasthenia (GT) is an uncommon accompaniment to immune thrombocytopenic purpura. Rarely, GT may present as an acquired autoimmune disorder of platelet function, with rapid onset of a moderate-to-severe bleeding tendency, a prolonged bleeding time, but with a normal platelet count and normal platelet glycoprotein (GP) expression. This is caused by an autoantibody with specificity for platelet GP IIb/IIIa or an epitope close to that of the GP, resulting in partial or complete refractoriness of the patient's platelets to ADP, collagen and arachidonic acid. We describe two patients with acquired GT and a normal platelet count, who presented with severe bleeding. The first patient responded gradually to immunosuppressive treatment but eventually developed non-Hodgkin's lymphoma. The second patient had no other underlying conditions and remitted spontaneously within 2 years.     

Developing functional musculoskeletal tissues through hypoxia and lysyl oxidase-induced collagen cross-linking

The inability to recapitulate native tissue biomechanics, especially tensile properties, hinders progress in regenerative medicine. To address this problem, strategies have focused on enhancing collagen production. However, manipulating collagen cross-links, ubiquitous throughout all tissues and conferring mechanical integrity, has been underinvestigated. A series of studies examined the effects of lysyl oxidase (LOX), the enzyme responsible for the formation of collagen cross-links. Hypoxia-induced endogenous LOX was applied in multiple musculoskeletal tissues (i.e., cartilage, meniscus, tendons, ligaments). Results of these studies showed that both native and engineered tissues are enhanced by invoking a mechanism of hypoxia-induced pyridinoline (PYR) cross-links via intermediaries like LOX. Hypoxia was shown to enhance PYR cross-linking 1.4- to 6.4-fold and, concomitantly, to increase the tensile properties of collagen-rich tissues 1.3- to 2.2-fold. Direct administration of exogenous LOX was applied in native cartilage and neocartilage generated using a scaffold-free, self-assembling process of primary chondrocytes. Exogenous LOX was found to enhance native tissue tensile properties 1.9-fold. LOX concentration- and time-dependent increases in PYR content (∼16-fold compared with controls) and tensile properties (approximately fivefold compared with controls) of neocartilage were also detected, resulting in properties on par with native tissue. Finally, in vivo subcutaneous implantation of LOX-treated neocartilage in nude mice promoted further maturation of the neotissue, enhancing tensile and PYR content approximately threefold and 14-fold, respectively, compared with in vitro controls. Collectively, these results provide the first report, to our knowledge, of endogenous (hypoxia-induced) and exogenous LOX applications for promoting collagen cross-linking and improving the tensile properties of a spectrum of native and engineered tissues both in vitro and in vivo.Regenerative medicine and tissue engineering are providing new avenues to treat a multitude of conditions and diseases through restoring, maintaining, or enhancing the function of a wide range of tissues (e.g., muscle, bone, skin) and organs (e.g., heart, lungs, kidneys). Despite recent advancements, the clinical utility of many engineered tissues remains dependent upon the development of methods that promote mechanically robust tissues capable of withstanding the in vivo environment. This problem presents a critical hurdle for efforts geared toward developing de novo musculoskeletal tissues, such as cartilage, meniscus, tendons, and ligaments, for reparative and regenerative strategies. Tissue engineering has the potential to provide alternative treatment options for musculoskeletal injury and disease by generating neotissue that mimics the complex structure of native tissue (1, 2). The objective is to improve the properties of the engineered tissues to achieve native tissue biomechanical properties, maturation, and long-term functionality. For example, in articular cartilage tissue engineering, a variety of methods, including combinations of hydrostatic pressure and growth factor treatment (3), fluid flow (4), and matrix-modulating enzymes (5), have resulted in improved neotissues with tensile moduli ranging from 1.3 to 2.3 MPa; however, native tissue values range from 5 to 25 MPa (6). Similarly, in neofibrocartilage, tensile properties have been reported to be 2.5–3.5 MPa (7, 8), with native fibrocartilage values ranging from 7 to 295 MPa (9, 10). These low properties likely result from the immaturity of the ECM of the neotissues, which is mainly due to lack of collagen cross-links (11). Therefore, it is important that additional treatment modalities be evaluated toward enhancing neotissue tensile properties.Collagen, the most prevalent fibrous protein in the body, supports the mechanical integrity of tissues and organs. In musculoskeletal tissues, collagen comprises the major fraction of the ECM and accounts for ∼65–80% of these tissues’ dry weights (12). After collagen biosynthesis and triple-helix formation, the copper-dependent enzyme lysyl oxidase (LOX) catalyzes extracellular modification of lysine and hydroxylysine amino acids of the collagen fibers into their aldehyde forms (Fig. 1A). Sequentially, this modification induces the formation of covalent pyridinoline (PYR) cross-links between individual collagen fibers (13) (Fig. 1B) and stabilizes the formation of heterotypic fibrils (Fig. 1C) and, subsequently, the tissue ECM. These intermolecular collagen cross-links, present in all native musculoskeletal tissues, signify the maturity of the tissue’s ECM (14). In particular, cartilaginous tissues, ligaments, and tendons feature two forms of collagen cross-links, the difunctional (initial/immature) cross-link dehydrodihydroxylysinonorleucine and the trifunctional (mature) cross-link hydroxylysyl-PYR (15) (Fig. 1B). Several studies have highlighted the pivotal role of these cross-links in native tissues’ biomechanical or functional properties (11, 16, 17). For example, in cartilage, the cross-linked collagen fibrils noncovalently stabilize the highly hydrated, negatively charged proteoglycans (18). These findings suggest the need for recapitulating cross-linking in engineered collagen-rich tissues.Open in a separate windowFig. 1.This illustration represents a hierarchical depiction of a heterotypic collagen fibril that is commonly found in most musculoskeletal tissues, such as cartilage, tendons, and ligaments. The figure emphasizes the internal axial relationships required for the formation of mature cross-links. (A) Detailed view of the axial stagger of individual collagen molecules required for PYR cross-linking. (B) Illustration of relationships among neighboring axial fibers of trifunctional (mature) hydroxylysyl-PYR collagen cross-links. (C) Illustration of a 3D concept of a heterotypic fibril, commonly found in musculoskeletal tissues, consisting of collagen types II (yellow), IX (red), and XI (blue). Figure adapted from ref. 68.Only a few studies to date have evaluated the extent of collagen cross-links (19, 20) and, more importantly, their influence on the tensile and compressive properties of engineered musculoskeletal tissues. In contrast, many studies have investigated how other ECM components, such as glycosaminoglycan (GAG), collagen, and mineralization, contribute to biomechanical properties (19, 21–23). Such work has yielded variable results. Specifically, although it has been suggested that the compressive properties of native articular cartilage are best correlated with the proteoglycan component of the ECM (24), more recent studies have shown a better correlation of the compressive modulus with a combination of both GAG and collagen content (25–27). For engineered tissues, tensile stiffness has been strongly associated with total collagen content (22) as well as PYR content (28). Nevertheless, a significant correlation with compressive properties has also been reported with respect to the PYR content of engineered tissues (28). These findings might suggest that the various tissue biomechanical properties are dependent on more than just the quantity of specific biochemical components (29). Therefore, the unique structural organization, cross-linking, and architecture of the collagen network also likely play equally important roles, along with collagen and GAG quantities, in determining the biomechanical functionality of the tissue.To the best of our knowledge, there are no validated and optimized methods for promoting collagen cross-linking and concomitant improvement in biomechanical properties in a spectrum of native and engineered tissues. Low oxygen tension, however, has been shown to have various molecular effects in different tissues (30, 31) through a hypoxia-dependent mechanism. This molecular mechanism is based on the critical involvement of hypoxia-inducible factor-1 (HIF-1) (32), which is present in many cells (33–35), including articular chondrocytes (36). In diarthrodial joints as well as developmental growth plates, chondrocytes experience hypoxic conditions (37). Low oxygen tension has been shown to affect the metabolism of articular chondrocytes, targeting the production of tissue-specific cartilage ECM proteins (38–42). Deletion of HIF-1α results in chondrocyte death, along with diminished expression of the cyclin-dependent kinase inhibitor p57, highlighting the importance of HIF-1 regulation for cell survival and growth arrest in this hypoxic environment (43). The critical role of HIF-1 in the chondrogenic differentiation of rat mesenchymal stem cells as well as human ES cells has been also identified (42, 44–46). Hypoxia-induced HIF-1 stabilization has been shown to control LOX regulation (47, 48), suggesting that hypoxia could affect ECM stabilization and tissue maturation through LOX-induced PYR cross-link formation. The manifold role of HIF-1 raises the intriguing idea that the ECM of native and engineered tissues and, concomitantly, their functional properties could be manipulated through hypoxia-mediated stimulation of HIF-1–regulated pathways, LOX gene expression, and sequential collagen cross-link formation.Although studies have elucidated the pathway underlying the effects of hypoxia on cartilage growth, function, and synthesis, the ability of endogenous (hypoxia-induced) and exogenous LOX application to enhance collagen cross-linking and concomitant mechanical properties in both native and engineered tissues remains unexplored and is the central hypothesis of the present study. In the series of studies presented here, a variety of musculoskeletal tissues widely used in clinical practice as grafts to replace degenerative tissues as well as neocartilage constructs were investigated to assess hypoxia- and LOX-mediated collagen cross-linking manipulation. The overall goal was to preserve and promote the functional properties of the native explants and neotissues, respectively. Strategically targeting collagen cross-links may be useful for engineering tissues de novo, for elucidating disease processes, and for the development of potential novel therapeutic modalities.     

Practical guidance for the management of adults with immune thrombocytopenia during the COVID-19 pandemic

This document aims to provide practical guidance for the assessment and management of patients with thrombocytopenia, with a particular focus on immune thrombocytopenia (ITP), during the COVID-19 pandemic. The intention is to support clinicians and, although recommendations have been provided, it is not a formal guideline. Nor is there sufficient evidence base to conclude that alternative approaches to treatment are incorrect. Instead, it is a consensus written by clinicians with an interest in ITP or coagulation disorders and reviewed by members of the UK ITP forum.     

Cholestatic syndrome with bile duct damage and loss in renal transplant recipients with HCV infection

BACKGROUND/AIMS: Bile duct cells are known to be susceptible to hepatitis B and C virus, while it has been recently suggested that hepatitis B virus (HBV) and hepatitis C virus (HCV) infection may have a direct role in the pathogenesis of vanishing bile duct syndrome (VBDS) after liver transplantation. We report the development of a cholestatic syndrome associated with bile duct damage and loss in four HCV-infected renal transplant recipients. METHODS: All four patients were followed up biochemically, serologically and with consecutive liver biopsies. Serum HCV RNA was quantitatively assessed and genotyping was performed. RESULTS: Three patients were anti-HCV negative and one was anti-HCV/HBsAg positive at the time of transplantation and received the combination of methylprednisolone, azathioprine and cyclosporine A. Two patients became anti-HCV positive 1 year and one patient 3 years post-transplantation. Elevation of the cholestatic enzymes appeared simultaneously with seroconversion, or 2-4 years later, and was related to lesions of the small-sized interlobular bile ducts. Early bile duct lesions were characterized by degenerative changes of the epithelium. Late and more severe bile duct damage was associated with bile duct loss. The progression of the cholestatic syndrome coincided with high HCV RNA serum levels, while HCV genotype was 1a and 1b. Two patients (one with HBV co-infection) developed progressive VBDS and died of liver failure 2 and 3 years after biochemical onset. One patient, despite developing VBDS within a 10-month period, showed marked improvement of liver function after cessation of immunosuppression because of graft loss. The fourth patient, who had mild biochemical and histological bile duct changes, almost normalized liver function tests after withdrawal of azathioprine. CONCLUSION: A progressive cholestatic syndrome due to bile duct damage and loss may develop in renal transplant patients with HCV infection. The occurrence of the lesions after the appearance of anti-HCV antibodies and the high HCV RNA levels are indicative of viral involvement in the pathogenesis. Withdrawal of immunosuppressive therapy may have a beneficial effect on the outcome of the disease.     

Soluble Flt-1 as a diagnostic marker of pre-eclampsia

BACKGROUND: Serum levels of soluble fms-like tyrosine kinase (sFlt-1) increase in pre-eclampsia (PE). Aims: To determine whether concentrations of serum sFlt-1 can differentiate PE or superimposed PE (SPE) from gestational hypertension (GH) or chronic hypertension (CH). METHODS: Blood was collected from pregnant women being investigated for hypertension (blood pressure of > 140 and/or 90 mmHg). Normotensive (NP) and pre-eclamptic (PE-C) control ranges were measured. RESULTS: Patients with evolving hypertension in pregnancy eventually fell into four groups: GH (n = 14), PE (n = 7), CH (n = 9) and SPE (n = 9). Patients who later developed pre-eclampsia had a higher sFlt-1 (PE: 2.61 ng/mL and SPE: 2.77 ng/mL, respectively) than GH (P < 0.001) or CH (1.05 ng/mL, P = 0.11). Women with established PE at recruitment (PE-C; (n = 18) (3.13 ng/mL; interquartile range (IQR): 2.14-4.17 ng/mL) had a median sFlt-1 higher than NP (n = 18) (0.47 ng/mL; IQR: 0.11-0.89) (P < 0.0008). Patients with GH compared to NP had a slight increase (1.33 ng/mL, P < 0.003). Using a sFlt-1 cut-off of > or = 1.9 ng/mL yielded a sensitivity of 94% (95% confidence interval (CI) 73-100%) and specificity of 78% (95% CI 64-82%). CONCLUSIONS: sFlt-1 was elevated in women with PE compared to NP. The sFlt-1 also differentiated women destined to develop PE among those who presented with a diagnostic rise in maternal blood pressure. The sFlt-1 test is a useful diagnostic test for PE.     

A systematic approach for identifying and presenting mechanistic evidence in human health assessments

Clear documentation of literature search and presentation methodologies can improve transparency in chemical hazard assessments. We sought to improve clarity for the scientific support for cancer mechanisms of action using a systematic approach to literature retrieval, selection, and presentation of studies. The general question was “What are the mechanisms by which a chemical may cause carcinogenicity in the target tissue?”. Di(2-ethylhexyl)phthalate was used as a case study chemical with a complex database of >3000 publications. Relevant mechanistic events were identified from published reviews. The PubMed search strategy included relevant synonyms and wildcards for DEHP and its metabolites, mechanistic events, and species of interest. Tiered exclusion/inclusion criteria for study pertinence were defined, and applied to the retrieved literature. Manual curation was conducted for mechanistic events with large literature databases. Literature trees documented identification and selection of the literature evidence. The selected studies were summarized in evidence tables accompanied by succinct narratives. Primary publications were deposited into the Health and Environmental Research Online (http://hero.epa.gov/) database and identified by pertinence criteria and key terms to permit organized retrieval. This approach contributes to human health assessment by effectively managing a large volume of literature, improving transparency, and facilitating subsequent synthesis of information across studies.