Generation of human cerebral organoids with a structured outer subventricular zone

Outer radial glia (oRG) emerge as cortical progenitor cells that support the development of an enlarged outer subventricular zone (oSVZ) and the expansion of the neocortex. The in vitro generation of oRG is essential to investigate the underlying mechanisms of human neocortical development and expansion. By activating the STAT3 signaling pathway using leukemia inhibitory factor (LIF), which is not expressed in guided cortical organoids, we define a cortical organoid differentiation method from human pluripotent stem cells (hPSCs) that recapitulates the expansion of a progenitor pool into the oSVZ. The oSVZ comprises progenitor cells expressing specific oRG markers such as GFAP, LIFR, and HOPX, closely matching human fetal oRG. Finally, incorporating neural crest-derived LIF-producing cortical pericytes into cortical organoids recapitulates the effects of LIF treatment. These data indicate that increasing the cellular complexity of the organoid microenvironment promotes the emergence of oRG and supports a platform to study oRG in hPSC-derived brain organoids routinely.

An epigenetic barrier sets the timing of human neuronal maturation

The pace of human brain development is highly protracted compared with most other species1-7. The maturation of cortical neurons is particularly slow, taking months to years to develop adult functions3-5. Remarkably, such protracted timing is retained in cortical neurons derived from human pluripotent stem cells (hPSCs) during in vitro differentiation or upon transplantation into the mouse brain4,8,9. Those findings suggest the presence of a cell-intrinsic clock setting the pace of neuronal maturation, although the molecular nature of this clock remains unknown. Here we identify an epigenetic developmental programme that sets the timing of human neuronal maturation. First, we developed a hPSC-based approach to synchronize the birth of cortical neurons in vitro which enabled us to define an atlas of morphological, functional and molecular maturation. We observed a slow unfolding of maturation programmes, limited by the retention of specific epigenetic factors. Loss of function of several of those factors in cortical neurons enables precocious maturation. Transient inhibition of EZH2, EHMT1 and EHMT2 or DOT1L, at progenitor stage primes newly born neurons to rapidly acquire mature properties upon differentiation. Thus our findings reveal that the rate at which human neurons mature is set well before neurogenesis through the establishment of an epigenetic barrier in progenitor cells. Mechanistically, this barrier holds transcriptional maturation programmes in a poised state that is gradually released to ensure the prolonged timeline of human cortical neuron maturation.

Combined small-molecule treatment accelerates maturation of human pluripotent stem cell-derived neurons

The maturation of human pluripotent stem cell (hPSC)-derived neurons mimics the protracted timing of human brain development, extending over months to years for reaching adult-like function. Prolonged in vitro maturation presents a major challenge to stem cell-based applications in modeling and treating neurological disease. Therefore, we designed a high-content imaging assay based on morphological and functional readouts in hPSC-derived cortical neurons which identified multiple compounds that drive neuronal maturation including inhibitors of lysine-specific demethylase 1 and disruptor of telomerase-like 1 and activators of calcium-dependent transcription. A cocktail of four factors, GSK2879552, EPZ-5676, N-methyl-D-aspartate and Bay K 8644, collectively termed GENtoniK, triggered maturation across all parameters tested, including synaptic density, electrophysiology and transcriptomics. Maturation effects were further validated in cortical organoids, spinal motoneurons and non-neural lineages including melanocytes and pancreatic β-cells. The effects on maturation observed across a broad range of hPSC-derived cell types indicate that some of the mechanisms controlling the timing of human maturation might be shared across lineages.

Clinical outcomes of non-surgical root canal obturations using NeoMTA: A retrospective series of case reports

NeoMTA is a commercially available tricalcium silicate-based cement intended for contact with pulp and periradicular tissues. The purpose of this study was to retrospectively evaluate the outcomes of non-surgical root canal treatments with NeoMTA obturations. Patients were treated in a private endodontic practice between 2015 and 2018. All cases, including initial treatments and retreatments, were either fully obturated with NeoMTA, or using gutta-percha with NeoMTA as an endodontic sealer. Outcomes were assessed using follow-up examination data with digital periapical radiographs with a minimum of a 1-year recall. Teeth were classified based on the clinical examination as: healed/healing (success), or non-healed (failure). 265 teeth were included with an average follow-up time of 1.3 years. The overall success rate was 91.7%. Only the presence of a pre-operative periapical radiolucency was found to significantly affect success. Comparison of obturation techniques demonstrated no effect on outcomes. NeoMTA is suitable for endodontic obturation.

The prevalence, characteristics, and risk factors of external cervical resorption: a retrospective practice-based study

OBJECTIVES

External cervical root resorption (ECR) is a poorly understood and aggressive form of resorption. The purpose of this study was to examine the prevalence, characteristics, and risk factors associated with the occurrence of ECR in patients seeking endodontic care from private practice settings.

MATERIALS AND METHODS

Records of 343 patients with 390 teeth diagnosed with ECR were identified from 3 private endodontic practices from 2008 to 2022. The patients' demographic information, systemic conditions, and dental history were recorded. The characteristics of the cases including Heithersay classification, pulpal and periapical status, and their management were documented. The association between case severity and potential predisposing factors was examined using chi-square analysis.

RESULTS

The overall prevalence of ECR among patients seeking endodontic care was low (< 1%). However, there was a greater than twofold increase in the pooled prevalence from 2016 to 2021 (0.99%) compared to the data from 2010 to 2015 (0.46%). The most commonly affected teeth were anterior teeth (48.7%). Class II (30.0%) and class III (45.4%) defects were the most often identified. Patients with a history of trauma or orthodontic treatment were significantly more likely to be diagnosed with severe cervical resorption (class III or IV) (p < 0.05).

CONCLUSIONS

There has been an increase in the prevalence of ECR in patients seeking endodontic care. A history of orthodontic treatment and traumatic dental mechanical injuries may predict the severity of resorption.

CLINICAL RELEVANCE

The upward trend in the occurrence of ECR warrants close monitoring of the patients at high risk of developing the condition to facilitate early detection and management.

A retrospective study of initial root canal treatment failure in maxillary premolars via using cone-beam computed tomography

BACKGROUND

This case-series study examined canal morphology and common factors for endodontic failure in maxillary first and second premolars that were referred for retreatment owing to clinical symptoms or radiographic signs.

METHODS

Records were retrospectively searched using Current Dental Terminology codes to identify maxillary first and second premolars with endodontic failure. Periapical and cone-beam computed tomographic images were examined to determine Vertucci classifications and suspected factors related to treatment failure.

RESULTS

A total of 235 teeth from 213 patients were included for evaluation. The following Vertucci classification of canal configurations were observed for maxillary first and second premolars: type I (1-1) (4.6% and 32.0%, respectively), type II (2-1) (15.9% and 27.9%, respectively), type III (2-2) (76.1% and 36.1%, respectively), type IV (1-2) (0% and 2%, respectively), and type V (3) (3.4% and 2%, respectively). More treatment failures were noticed in maxillary second premolars than first premolars and in females than in males. The 4 most common factors related to failure were inadequate filling, restorative failure, vertical root fracture, and missed canals. Missed canals were more frequently identified in maxillary second premolars (21.8%) than first premolars (11.4%) (P = .044).

CONCLUSIONS

Multiple factors are associated with primary root canal treatment failures in maxillary premolars. Variations in canal morphology appear to be underappreciated in maxillary second premolars.

PRACTICAL IMPLICATIONS

Maxillary second premolars have more complicated canal configurations than first premolars. Besides adequate filling, clinicians should give extra attention to anatomic variability in second premolars owing to higher failure incidence.

Dissection of gastric homeostasis in vivo facilitates permanent capture of isthmus-like stem cells in vitro

The glandular stomach is composed of two regenerative compartments termed corpus and antrum, and our understanding of the transcriptional networks that maintain these tissues is incomplete. Here we show that cell types with equivalent functional roles in the corpus and antrum share similar transcriptional states including the poorly characterized stem cells of the isthmus region. To further study the isthmus, we developed a monolayer two-dimensional (2D) culture system that is continually maintained by Wnt-responsive isthmus-like cells capable of differentiating into several gastric cell types. Importantly, 2D cultures can be converted into conventional three-dimensional organoids, modelling the plasticity of gastric epithelial cells in vivo. Finally, we utilized the 2D culture system to show that Sox2 is both necessary and sufficient to generate enterochromaffin cells. Together, our data provide important insights into gastric homeostasis, establish a tractable culture system to capture isthmus cells and uncover a role for Sox2 in enterochromaffin cells.

Scleroderma and multiple teeth with invasive cervical resorption: is there a connection?

Scleroderma is a chronic connective tissue disease generally classified as an autoimmune rheumatic disease. Symptoms may include thickening of the skin, calcifications, Raynaud syndrome, and esophageal problems. Invasive cervical resorption is an aggressive form of external resorption localized in the cervical part of the tooth. Its etiology remains uncertain. This case report describes invasive cervical resorption affecting 4 teeth in a 44-year-old woman with scleroderma and speculates on the possible relationships between these disease entities.

Developmental chromatin programs determine oncogenic competence in melanoma

[Figure: see text].

Activation of HERV-K(HML-2) disrupts cortical patterning and neuronal differentiation by increasing NTRK3

The biological function and disease association of human endogenous retroviruses (HERVs) are largely elusive. HERV-K(HML-2) has been associated with neurotoxicity, but there is no clear understanding of its role or mechanistic basis. We addressed the physiological functions of HERV-K(HML-2) in neuronal differentiation using CRISPR engineering to activate or repress its expression levels in a human-pluripotent-stem-cell-based system. We found that elevated HERV-K(HML-2) transcription is detrimental for the development and function of cortical neurons. These effects are cell-type-specific, as dopaminergic neurons are unaffected. Moreover, high HERV-K(HML-2) transcription alters cortical layer formation in forebrain organoids. HERV-K(HML-2) transcriptional activation leads to hyperactivation of NTRK3 expression and other neurodegeneration-related genes. Direct activation of NTRK3 phenotypically resembles HERV-K(HML-2) induction, and reducing NTRK3 levels in context of HERV-K(HML-2) induction restores cortical neuron differentiation. Hence, these findings unravel a cell-type-specific role for HERV-K(HML-2) in cortical neuron development.

Inducible histone K-to-M mutations are dynamic tools to probe the physiological role of site-specific histone methylation in vitro and in vivo

Development and differentiation are associated with profound changes to histone modifications, yet their in vivo function remains incompletely understood. Here, we generated mouse models expressing inducible histone H3 lysine-to-methionine (K-to-M) mutants, which globally inhibit methylation at specific sites. Mice expressing H3K36M developed severe anaemia with arrested erythropoiesis, a marked haematopoietic stem cell defect, and rapid lethality. By contrast, mice expressing H3K9M survived up to a year and showed expansion of multipotent progenitors, aberrant lymphopoiesis and thrombocytosis. Additionally, some H3K9M mice succumbed to aggressive T cell leukaemia/lymphoma, while H3K36M mice exhibited differentiation defects in testis and intestine. Mechanistically, induction of either mutant reduced corresponding histone trimethylation patterns genome-wide and altered chromatin accessibility as well as gene expression landscapes. Strikingly, discontinuation of transgene expression largely restored differentiation programmes. Our work shows that individual chromatin modifications are required at several specific stages of differentiation and introduces powerful tools to interrogate their roles in vivo.

Histology of NeoMTA Plus and Quick-Set2 in Contact with Pulp and Periradicular Tissues in a Canine Model

INTRODUCTION

NeoMTA Plus (Avalon Biomed Inc, Bradenton, FL) is a tricalcium silicate material similar to the first mineral trioxide aggregate product, ProRoot MTA (Dentsply Sirona, York, PA), but with improvements such as decreased setting time, increased ion release, increased water sorption, and nonstaining radiopacifiers. Quick-Set2 (Avalon Biomed Inc) is a newly formulated calcium aluminosilicate material that has a faster setting time and increased acid resistance and is nonstaining. The purpose of this study was to compare the healing of pulpal and periapical tissues in dogs after exposure to NeoMTA Plus and Quick-Set2 after pulpotomy and root-end surgery procedures.

METHODS

Seventy-two teeth (36 for each procedure) in 6 beagle dogs received pulpotomy or root-end surgery using either NeoMTA Plus or Quick-Set2. The dogs were sacrificed at 90 days, and the teeth and surrounding tissues were prepared for histologic evaluation. Sixty teeth were evaluated and scored histologically (29 with pulpotomies and 31 with root-end resections). Specimens were scored for inflammation, quality and thickness of dentin bridging, pulp tissue response, cementum and periodontal ligament formation, and apical bone healing.

RESULTS

Both materials displayed favorable healing at 90 days. The only significant difference was the quality of dentin bridge formation in pulpotomies using NeoMTA Plus compared with Quick-Set2.

CONCLUSIONS

Quick-Set2 and NeoMTA Plus had similar effects on inflammation, pulp response, periodontal ligament and cementum formation, and apical tissue healing in dogs. NeoMTA Plus had superior dentin bridge quality compared with Quick-Set2.

Prospective Isolation of Poised iPSC Intermediates Reveals Principles of Cellular Reprogramming

Cellular reprogramming converts differentiated cells into induced pluripotent stem cells (iPSCs). However, this process is typically very inefficient, complicating mechanistic studies. We identified and molecularly characterized rare, early intermediates poised to reprogram with up to 95% efficiency, without perturbing additional genes or pathways, during iPSC generation from mouse embryonic fibroblasts. Analysis of these cells uncovered transcription factors (e.g., Tfap2c and Bex2) that are important for reprogramming but dispensable for pluripotency maintenance. Additionally, we observed striking patterns of chromatin hyperaccessibility at pluripotency loci, which preceded gene expression in poised intermediates. Finally, inspection of these hyperaccessible regions revealed an early wave of DNA demethylation that is uncoupled from de novo methylation of somatic regions late in reprogramming. Our study underscores the importance of investigating rare intermediates poised to produce iPSCs, provides insights into reprogramming mechanisms, and offers a valuable resource for the dissection of transcriptional and epigenetic dynamics intrinsic to cell fate change.

Bioactive endodontic materials for everyday use: a review

Bioceramic materials are at the forefront of modern dentistry. Bioactive bioceramic endodontic materials promote pulpal and periapical tissue healing and are easy to use. Dentists can choose among many endodontic materials, depending on their needs. This article highlights the major differences among commercially available bioactive tricalcium silicate bioceramics, commonly known as mineral trioxide aggregate materials, to enable dentists to make appropriate decisions in the selection of these materials.

Prolonged Mek1/2 suppression impairs the developmental potential of embryonic stem cells

Concomitant activation of the Wnt pathway and suppression of Mapk signalling by two small molecule inhibitors (2i) in the presence of leukaemia inhibitory factor (LIF) (hereafter termed 2i/L) induces a naive state in mouse embryonic stem (ES) cells that resembles the inner cell mass (ICM) of the pre-implantation embryo. Since the ICM exists only transiently in vivo, it remains unclear how sustained propagation of naive ES cells in vitro affects their stability and functionality. Here we show that prolonged culture of male mouse ES cells in 2i/L results in irreversible epigenetic and genomic changes that impair their developmental potential. Furthermore, we find that female ES cells cultured in conventional serum plus LIF medium phenocopy male ES cells cultured in 2i/L. Mechanistically, we demonstrate that the inhibition of Mek1/2 is predominantly responsible for these effects, in part through the downregulation of DNA methyltransferases and their cofactors. Finally, we show that replacement of the Mek1/2 inhibitor with a Src inhibitor preserves the epigenetic and genomic integrity as well as the developmental potential of ES cells. Taken together, our data suggest that, although short-term suppression of Mek1/2 in ES cells helps to maintain an ICM-like epigenetic state, prolonged suppression results in irreversible changes that compromise their developmental potential.

What is the fate of the cholecystostomy tube following percutaneous cholecystostomy?

INTRODUCTION

Cholecystectomy is the preferred treatment for acute cholecystitis with percutaneous cholecystostomy (PC) considered an alternative therapy in severely debilitated patients. The aim of this study was to evaluate the efficacy and outcomes of PC at a tertiary referral center.

METHODS

We retrospectively reviewed all patients that had undergone PC from 2000 to 2014. Data collected included baseline demographics, comorbidities, details of PC placement and management, and post-procedure outcomes. The Charlson comorbidity index (CCI) was calculated for all patients at the time of PC.

RESULTS

Four hundred and twenty-four patients underwent PC placement from 2000 to 2014, and a total of 380 patients had long-term data available for review. Within this cohort, 223 (58.7 %) of the patients were male. The mean age at the time of PC placement was 65.3 ± 14.2 years of age, and the mean CCI was 3.2 ± 2.1 for all patients. One hundred and twenty-five (32.9 %) patients went on to have a cholecystectomy following PC placement. Comparison of patients who underwent PC followed by surgical intervention revealed that they were significantly younger (p = 0.0054) and had a lower CCI (p < 0.0001) compared to those who underwent PC alone.

CONCLUSIONS

PC placement appears to be a viable, long-term alternative to cholecystectomy for the management of biliary disease in high-risk patients. Old and frail patients benefit the most, and in this cohort PC may be the definitive treatment.

Two randomized, double-blind, placebo-controlled, dose-escalation phase 1 studies evaluating BTH1677, a 1, 3-1,6 beta glucan pathogen associated molecular pattern, in healthy volunteer subjects

BACKGROUND

BTH1677 is a beta glucan pathogen associated molecular pattern (PAMP) currently being investigated as a novel cancer therapy. Here, the initial safety and pharmacokinetic (PK) results of BTH1677 in healthy subjects are reported.

SUBJECTS AND METHODS

In the Phase 1a single-dosing study, subjects were randomized (3:1 per cohort) to a single intravenous (i.v.) infusion of BTH1677 at 0.5, 1, 2, 4, or 6 mg/kg or placebo, respectively. In the Phase 1b multi-dosing study, subjects were randomized (3:1 per cohort) to 7 daily i.v. infusions of BTH1677 at 1, 2, or 4 mg/kg or placebo, respectively. Safety and PK non-compartmental analyses were performed.

RESULTS

Thirty-six subjects (N = 24 Phase 1a; N = 12 Phase 1b) were randomized to treatment. No deaths or serious adverse events occurred in either study. Mild or moderate adverse events (AEs) occurred in 67% of BTH1677-treated subjects in both studies. Treatment-related AEs (occurring in ≥10% of subjects) included dyspnea, flushing, headache, nausea, paraesthesia, and rash in Phase 1a and conjunctivitis and headache in Phase 1b. BTH1677 serum concentration was linear with dose. Clearance, serum elimination half-life (t1/2) and volume of distribution (Vss) were BTH1677 dose-independent. In Phase 1b, area under the curve, t1/2, and Vss values were larger at steady state on days 6-30 versus day 0.

CONCLUSIONS

BTH1677 was well tolerated after single doses up to 6 mg/kg and after 7 daily doses up to 4 mg/kg.

Comparison of Preloaded Bougie versus Standard Bougie Technique for Endotracheal Intubation in a Cadaveric Model

INTRODUCTION

We compared intubating with a preloaded bougie (PB) against standard bougie technique in terms of success rates, time to successful intubation and provider preference on a cadaveric airway model.

METHODS

In this prospective, crossover study, healthcare providers intubated a cadaver using the PB technique and the standard bougie technique. Participants were randomly assigned to start with either technique. Following standardized training and practice, procedural success and time for each technique was recorded for each participant. Subsequently, participants were asked to rate their perceived ease of intubation on a visual analogue scale of 1 to 10 (1=difficult and 10=easy) and to select which technique they preferred.

RESULTS

47 participants with variable experience intubating were enrolled at an emergency medicine intern airway course. The success rate of all groups for both techniques was equal (95.7%). The range of times to completion for the standard bougie technique was 16.0-70.2 seconds, with a mean time of 29.7 seconds. The range of times to completion for the PB technique was 15.7-110.9 seconds, with a mean time of 29.4 seconds. There was a non-significant difference of 0.3 seconds (95% confidence interval -2.8 to 3.4 seconds) between the two techniques. Participants rated the relative ease of intubation as 7.3/10 for the standard technique and 7.6/10 for the preloaded technique (p=0.53, 95% confidence interval of the difference -0.97 to 0.50). Thirty of 47 participants subjectively preferred the PB technique (p=0.039).

CONCLUSION

There was no significant difference in success or time to intubation between standard bougie and PB techniques. The majority of participants in this study preferred the PB technique. Until a clear and clinically significant difference is found between these techniques, emergency airway operators should feel confident in using the technique with which they are most comfortable.

The histone deacetylase SIRT6 controls embryonic stem cell fate via TET-mediated production of 5-hydroxymethylcytosine

How embryonic stem cells (ESCs) commit to specific cell lineages and yield all cell types of a fully formed organism remains a major question. ESC differentiation is accompanied by large-scale histone and DNA modifications, but the relations between these epigenetic categories are not understood. Here we demonstrate the interplay between the histone deacetylase sirtuin 6 (SIRT6) and the ten-eleven translocation enzymes (TETs). SIRT6 targets acetylated histone H3 at Lys 9 and 56 (H3K9ac and H3K56ac), while TETs convert 5-methylcytosine into 5-hydroxymethylcytosine (5hmC). ESCs derived from Sirt6 knockout (S6KO) mice are skewed towards neuroectoderm development. This phenotype involves derepression of OCT4, SOX2 and NANOG, which causes an upregulation of TET-dependent production of 5hmC. Genome-wide analysis revealed neural genes marked with 5hmC in S6KO ESCs, thereby implicating TET enzymes in the neuroectoderm-skewed differentiation phenotype. We demonstrate that SIRT6 functions as a chromatin regulator safeguarding the balance between pluripotency and differentiation through Tet-mediated production of 5hmC.

Change in Trauma Narratives and Perceived Recall Ability over a Course of Cognitive Processing Therapy for PTSD

This study sought to evaluate changes in written trauma narratives completed during a course of Cognitive Processing Therapy (CPT). Participants were 22 female survivors of interpersonal assault who represented a subset of participants from two larger CPT treatment trials. Participants completed two written trauma narratives over the course of treatment. We predicted that narratives would increase in length and peritraumatic detail, and that participants would perceive an increase in their recall ability for important aspects of the trauma. Although narrative length and amount of peritraumatic detail did not change significantly from first to final narrative, participants evidenced changes in the content of the peritraumatic details. Patients commonly omitted assaultive acts from one of their narratives. There was a greater degree of fluctuation within the reporting of sexual assaults, as compared to physical assaults, with 55% of participants reporting a forced sexual act in one narrative, but not the other. Participants did not report significant changes in perceived recall ability for the traumatic event after completing the narratives, but did report improvements in perceived recall from pre to posttreatment. Overall, findings indicate that clients included different details (but not more details) in their final narrative, and that perceived increases in recall ability may not be a typical experience for clients as they complete written narratives in the context of trauma treatment.

Small molecules facilitate rapid and synchronous iPSC generation

The reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) upon overexpression of OCT4, KLF4, SOX2, and c-MYC (OKSM) provides a powerful system to interrogate basic mechanisms of cell fate change. However, iPSC formation with standard methods is protracted and inefficient, resulting in heterogeneous cell populations. Here we show that exposure of OKSM-expressing cells to both ascorbic acid and a GSK3-beta inhibitor (termed “AGi”) facilitates more synchronous and rapid iPSC formation from a variety of mouse cell types. AGi treatment restored the ability of refractory cell populations to yield iPSC colonies, and it attenuated the activation of developmental regulators commonly observed during the reprogramming process. Moreover, AGi supplementation gave rise to chimera-competent iPSCs after as little as 48 hours of OKSM expression. Our results offer a simple modification to the reprogramming protocol, facilitating iPSC induction at unparalleled efficiencies and enabling dissection of the underlying mechanisms in more homogeneous cell populations.

Genome-wide chromatin interactions of the Nanog locus in pluripotency, differentiation, and reprogramming

The chromatin state of pluripotency genes has been studied extensively in embryonic stem cells (ESCs) and differentiated cells, but their potential interactions with other parts of the genome remain largely unexplored. Here, we identified a genome-wide, pluripotency-specific interaction network around the Nanog promoter by adapting circular chromosome conformation capture sequencing. This network was rearranged during differentiation and restored in induced pluripotent stem cells. A large fraction of Nanog-interacting loci were bound by Mediator or cohesin in pluripotent cells. Depletion of these proteins from ESCs resulted in a disruption of contacts and the acquisition of a differentiation-specific interaction pattern prior to obvious transcriptional and phenotypic changes. Similarly, the establishment of Nanog interactions during reprogramming often preceded transcriptional upregulation of associated genes, suggesting a causative link. Our results document a complex, pluripotency-specific chromatin "interactome" for Nanog and suggest a functional role for long-range genomic interactions in the maintenance and induction of pluripotency.

A molecular roadmap of reprogramming somatic cells into iPS cells

Factor-induced reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) is inefficient, complicating mechanistic studies. Here, we examined defined intermediate cell populations poised to becoming iPSCs by genome-wide analyses. We show that induced pluripotency elicits two transcriptional waves, which are driven by c-Myc/Klf4 (first wave) and Oct4/Sox2/Klf4 (second wave). Cells that become refractory to reprogramming activate the first but fail to initiate the second transcriptional wave and can be rescued by elevated expression of all four factors. The establishment of bivalent domains occurs gradually after the first wave, whereas changes in DNA methylation take place after the second wave when cells acquire stable pluripotency. This integrative analysis allowed us to identify genes that act as roadblocks during reprogramming and surface markers that further enrich for cells prone to forming iPSCs. Collectively, our data offer new mechanistic insights into the nature and sequence of molecular events inherent to cellular reprogramming.

Cdc42 GTPase and Rac1 GTPase act downstream of p120 catenin and require GTP exchange during gastrulation of zebrafish mesoderm

BACKGROUND

We investigated the roles of p120 catenin, Cdc42, Rac1, and RhoA GTPases in regulating migration of presomitic mesoderm cells in zebrafish embryos. p120 catenin has dual roles: It binds the intracellular and juxtamembrane region of cadherins to stabilize cadherin-mediated adhesion with the aid of RhoA GTPase, and it activates Cdc42 GTPase and Rac1 GTPase in the cytosol to initiate cell motility.

RESULTS

During gastrulation of zebrafish embryos, knockdown of the synthesis of zygotic p120 catenin δ1 mRNAs with a splice-site morpholino caused lateral widening and anterior-posterior shortening of the presomitic mesoderm and somites and a shortened anterior-posterior axis. These phenotypes indicate a cell-migration effect. Co-injection of low amounts of wild-type Cdc42 or wild-type Rac1 or dominant-negative RhoA mRNAs, but not constitutively-active Cdc42 mRNA, rescued these p120 catenin δ1-depleted embryos.

CONCLUSIONS

These downstream small GTPases require appropriate spatiotemporal stimulation or cycling of GTP to guide mesodermal cell migration. A delicate balance of Rho GTPases and p120 catenin underlies normal development.

Improved quality of life following total pancreatectomy and auto-islet transplantation for chronic pancreatitis

BACKGROUND

Total pancreatectomy (TP) with auto-islet transplant (AIT) is an extreme treatment for chronic pancreatitis, and we reviewed our experience to assess the impact on quality of life (QOL).

METHODS

A prospective cohort study from 2007 through 2010 with pre- and postoperative assessments of the Depression Anxiety Stress Scale, Pain Disability Index, and visual analogue pain scale was performed.

RESULTS

Twenty patients underwent TP-AIT with a median follow-up of 12 months (6.75-24 months). All patients reported moderate (45 %) to severe (55 %) pain prior to surgery. TP-AIT resulted in significant decreases in abdominal pain (p < 0.001), 80 % reporting no or mild pain. Despite pain improvement, only 30 % discontinued narcotics. Improvements in all PDI QOL domains improved from 79 to 90 % (p = 0.002), with greatest improvements seen in those without prior pancreatic surgery, younger patients, and in those with higher levels of preoperative pain. Patients were less affected by depression and anxiety prior to surgery, but 60 and 70 % did show improvement in depression and anxiety, respectively (p = 0.033). Sixteen patients (80 %) required exogenous insulin at last follow-up (mean total dose of insulin 11.6 U/day).

CONCLUSIONS

TP-AIT significantly improves pain and QOL measures in appropriately selected patients with CP.

Laparoscopic robotic-assisted pancreaticoduodenectomy: a case-matched comparison with open resection

BACKGROUND

Minimally invasive procedures have expanded recently to include pancreaticoduodenectomy (PD), but the efficacy of a laparoscopic robotic-assisted approach has not been demonstrated. A case-matched comparison was undertaken to study outcomes between laparoscopic robotic approach (LRPD) and the conventional open counterpart (OPD).

METHODS

From March 2009 through December 2010, 30 LRPD were performed by two pancreaticobiliary surgeons at the Cleveland Clinic. Thirty OPD patients operated by four pancreaticobiliary surgeons during this same period were matched by demographics, and postoperative outcomes were compared from review of a prospectively collected database.

RESULTS

Mean age was 62 years for LRPD versus 61 years for OPD (p = 0.43). Mean body mass index was 24.8 versus 25.6 kg/m(2) (p = 0.49). Surgical indications included adenocarcinoma in 14 patients from each group (46%), intraductal papillary mucinous neoplasm in 4 (14%), and other in 12 (40%). There was one preoperative death in the LRPD group and none following OPD. Morbidity occurred in nine patients (30%) following LRPD versus 13 (44%) in the OPD group (p = 0.14). Intraoperative factors assessed included blood loss (485.8 vs 775 ml, p = 0.13) and operative time (476.2 vs 366.4 min, p = 0.0005). Conversion from LRPD to open occurred in three patients (12%) due to bleeding. Reoperation was performed in two patients (6%) following LRPD versus seven (24%) following OPD (p = 0.17). Length of hospital stay was 9.79 days for LRPD versus 13.26 days in the OPD group (p = 0.043).

CONCLUSIONS

This is the first comparison of a novel laparoscopic robotic-assisted PD with the open PD in a case-matched fashion. Our data demonstrate a significant increase in operative time but decreased length of stay for LRPD. The favorable morbidity following LRPD makes it a reasonable surgical approach for selected patients requiring PD.

Ascorbic acid prevents loss of Dlk1-Dio3 imprinting and facilitates generation of all-iPS cell mice from terminally differentiated B cells

The generation of induced pluripotent stem cells (iPSCs) often results in aberrant epigenetic silencing of the imprinted Dlk1-Dio3 gene cluster, which compromises the cells’ ability to generate entirely iPSC-derived adult mice (“all-iPSC mice”). Here, we show that reprogramming in the presence of ascorbic acid attenuates hypermethylation of Dlk1-Dio3 by enabling a chromatin configuration that interferes with binding of the de novo DNA methyltransferase Dnmt3a. This allowed us to generate all-iPSC mice from mature B cells, which have thus far failed to support the development of exclusively iPSC-derived postnatal animals. Our data demonstrate that transcription factor-mediated reprogramming can endow a defined, terminally differentiated cell type with a developmental potential equivalent to that of embryonic stem cells. More generally, these findings indicate that culture conditions during cellular reprogramming can strongly influence the epigenetic and biological properties of resultant iPSCs.

Somatostatin therapy for glomus tumors: a report of two cases

Glomus tumors of the head and neck are benign vascular lesions that often provide dilemmas in management. The presence of somatostatin receptors on the tumor cell surface has facilitated an additional imaging technique in the form of radiolabeled octreotide scanning. The use of the somatostatin analogue, octreotide, also provides a therapeutic option for inoperable or recurrent tumors. We present two patients, one with a surgically inaccessible tumor that recurred after primary radiotherapy and one who underwent incomplete resection because of the tumor's proximity to the internal carotid artery. Neither tumor has shown further growth 5 and 3 years after treatment with octreotide, respectively.

The Relationships Between Perceived Levels of Control, Psychological Distress, and Legal System Variables in a Sample of Sexual Assault Survivors

Information regarding psychological distress, perceived levels of temporal control, and legal system success and satisfaction ratings were collected from 41 survivors of sexual assault. Results suggest that self-blame and offender blame may differentially impact posttraumatic stress disorder (PTSD) and depressive symptom severity. In addition, participants who perceived a greater risk of future assault reported higher levels of depressive and PTSD symptoms. Furthermore, perceptions of present control over the recovery process were related to lower levels of psychological distress. For those who reported the assault to police, lower levels of legal system success and satisfaction were linked to higher levels of perceived control over present recovery.

Modeling Rett syndrome with stem cells

The discovery that somatic cells can be reprogrammed into induced pluripotent stem cells (iPSCs) raised the exciting possibility of modeling diseases with patient-specific cells. Marchetto et al. (2010) now use iPSC technology to generate, characterize, and treat an in vitro model for the autism spectrum disorder Rett syndrome.

MicroRNA miR-210 modulates cellular response to hypoxia through the MYC antagonist MNT

The hypoxia-inducible factor (HIF) pathway is essential for cell survival under low oxygen and plays an important role in tumor cell homeostasis. We investigated the function of miR-210, the most prominent microRNA upregulated by hypoxia and a direct transcriptional target of HIFs. miR-210 expression was elevated in multiple cancer types and correlated with metastasis of breast and melanoma tumors. miR-210 overexpression in cancer cell lines bypassed hypoxia-induced cell cycle arrest and partially reversed the hypoxic gene expression signature. We identified MNT, a known MYC antagonist, as a miR-210 target. MNT mRNA contains multiple miR-210 binding sites in the 3' UTR and its knockdown phenocopied miR-210 overexpression. Furthermore, loss of MYC abolished miR-210-mediated override of hypoxia-induced cell cycle arrest. Comparison of miR-210 and MYC overexpression with MNT knockdown signatures also indicated that miR-210 triggered a "MYC-like" transcriptional response. Thus, miR-210 influences the hypoxia response in tumor cells through targeting a key transcriptional repressor of the MYC-MAX network.

Immortalization eliminates a roadblock during cellular reprogramming into iPS cells

The overexpression of defined transcription factors in somatic cells results in their reprogramming into induced pluripotent stem (iPS) cells. The extremely low efficiency and slow kinetics of in vitro reprogramming suggest that further rare events are required to generate iPS cells. The nature and identity of these events, however, remain elusive. We noticed that the reprogramming potential of primary murine fibroblasts into iPS cells decreases after serial passaging and the concomitant onset of senescence. Consistent with the notion that loss of replicative potential provides a barrier for reprogramming, here we show that cells with low endogenous p19(Arf) (encoded by the Ink4a/Arf locus, also known as Cdkn2a locus) protein levels and immortal fibroblasts deficient in components of the Arf-Trp53 pathway yield iPS cell colonies with up to threefold faster kinetics and at a significantly higher efficiency than wild-type cells, endowing almost every somatic cell with the potential to form iPS cells. Notably, the acute genetic ablation of Trp53 (also known as p53) in cellular subpopulations that normally fail to reprogram rescues their ability to produce iPS cells. Our results show that the acquisition of immortality is a crucial and rate-limiting step towards the establishment of a pluripotent state in somatic cells and underscore the similarities between induced pluripotency and tumorigenesis.

Comparison of laparoscopic versus open liver tumor resection: a case-controlled study

BACKGROUND

Although there are data in the literature about the safety and efficacy of laparoscopic liver resections, there are not many studies comparing laparoscopic versus open approaches in a case-matched design. The purpose of this study is to compare the perioperative outcome of laparoscopic versus open liver resections from a single institution.

METHODS

Thirty-one patients underwent laparoscopic liver resection between April 1997 and August 2007, with a prospective laparoscopic program started in April 2006 (n=25). This group of patients was compared with 43 consecutive patients undergoing open resection who were matched by size of the lesion (5 cm or less for malignant and 8 cm or less for benign), anatomical location (segments 2, 3, 4b, 5, 6), and type of resection (wedge resection, segmentectomy, partial liver resection). Data were obtained from medical records as well as from a prospective database. Statistical analysis was performed using t-test and chi-square. All data are expressed as mean +/- standard error on the mean (SEM).

RESULTS

Mean age in the laparoscopic group was 57.6+/-2.7 years versus 61.9+/-2.3 years in the open group (p=0.2). There were more women in the laparoscopic group [74% females (n=23) and 26% males (n=8)] versus in the open group [40% females (n=17) and 60% males (n=26)] (p=0.003). There were more patients with malignant lesions in the open group (73%) versus in the laparoscopic group (45%) (p=0.01). Eight patients underwent partial and 23 patients segmental/wedge liver resection in the laparoscopic group versus 15 patients who underwent partial and 28 patients segmental/wedge liver resection in the open group (p=0.7). Mean tumor size was 3.9+/-0.4 cm in the laparoscopic group versus 4.2+/-0.3 cm in the open group (p=0.5). Ten (32%) out of 31 cases in the laparoscopic group were hand-assisted. Inflow occlusion was used in 1 case (3%) in the laparoscopic group versus 16 (37.2%) in the open group. Mean operating time was 201+/-15 min for the laparoscopic group and 172+/-12 min for the open group (p=0.1). Mean estimated blood loss during the procedure was 122.5+/-45.4 cc for the laparoscopic group and 299.6+/-33.6 cc for the open group (p=0.002). Surgical margin was similar for malignant cases in both groups. Mean hospital stay was 3.2+/-1.0 days for the laparoscopic group and 6.8+/-0.7 days for the open group (p=0.004). The incidence of postoperative complications was 13% (n=4) in the laparoscopic and 16% (n=7) in the open group (p=0.7).

CONCLUSION

This study shows that, with a longer operative time, the laparoscopic approach, despite the learning curve, offers advantages regarding operative blood loss, postoperative analgesic requirement, time to regular diet, hospital stay, and overall cost compared with the open approach for minor liver resections.

Day of surgery admission--is this safe practise?

Day of surgery admission (DOSA) describes the process whereby patients are admitted to hospital and have surgery, on the same day. This is the current admission policy in our institution, for most elective Otolaryngology Head and Neck Surgery patients. We audited 75 consecutive patients admitted on the same day as surgery within our department between May 2006 and January 2007. Significant comorbidity was seen in 28 patients (37.3%). Preoperative investigations prior to surgery were conducted in 64 patients (85.3%). About 21 patients (28%) were delayed going to theatre and the average length of delay was 51 mins. Our cancellation rate was 5.3%. Hospital management have embraced the concept of DOSA in our institution without evaluating the risk to patients. If the DOSA policy is to continue it is imperative that an adequate preoperative assessment clinic is established to prevent negative outcomes for our patients.

Distribution of interstitial cells of Cajal and nitrergic neurons in normal and diabetic human appendix

The objective of this study was to determine the distribution of enteric nerves and interstitial cells of Cajal (ICC) in the normal human appendix and in type 1 diabetes. Appendixes were collected from patients with type 1 diabetes and from non-diabetic controls. Volumes of nerves and ICC were determined using 3-D reconstruction and neuronal nitric oxide synthase (nNOS) expressing neurons were counted. Enteric ganglia were found in the myenteric plexus region and within the longitudinal muscle. ICC were found throughout the muscle layers. In diabetes, c-Kit positive ICC volumes were significantly reduced as were nNOS expressing neurons. In conclusion, we describe the distribution of ICC and enteric nerves in health and in diabetes. The data also suggest that the human appendix, a readily available source of human tissue, may be useful model for the study of motility disorders.

Induction of nasal hyper-responsiveness by allergen challenge in allergic rhinitis: the role of afferent and efferent nerves

BACKGROUND

Hyper-responsiveness of nasal secretory function and volume changes are features of allergic rhinitis (AR) that are mediated in part by neural mechanisms. The finding of nasal hyper-responsiveness in subjects with AR who are currently symptomatic, but not in those who are currently out of season and asymptomatic, suggests that induction of neural reflexes in allergic subjects occurs as a result of allergic inflammation.

OBJECTIVES

To investigate whether allergen exposure in subjects with asymptomatic seasonal allergic rhinitis (SAR) may lead to induction of neural reflexes, and to investigate the components of the reflexes involved in this induction.

METHODS

Asymptomatic subjects with (out-of-season) SAR underwent a nasal bradykinin challenge, before and 24 h after preceding ipsilateral (n = 11) and contralateral (n = 11) antigen challenge. Challenges were performed and nasal secretions collected using filter paper disks, and changes in nasal minimal cross-sectional area (A(min)) were measured using acoustic rhinometry.

RESULTS

Preceding ipsilateral antigen challenge led to the induction of a contralateral secretory reflex (P = 0.01), which was absent in control experiments (P = 0.34). Ipsilateral secretion weights were also enhanced. Preceding contralateral antigen challenge also induced a contralateral secretory reflex (P = 0.03). Enhancement of the reduction in contralateral A(min) was also seen (P = 0.02). Ipsilateral responses were unchanged.

CONCLUSIONS

Allergen exposure in asymptomatic allergic subjects leads to induction of neural reflexes, resulting in nasal hyper-responsiveness, which persists beyond the resolution of the acute allergic response. Our data suggest that the mechanisms of allergen-induced hyper-responsiveness involve both afferent and efferent components.

Conservative management of vestibular schwannomas - second review of a prospective longitudinal study

Vestibular schwannomas have been traditionally managed with microsurgical removal and in recent years, stereotactic radiotherapy. However, there is a group of patients in whom a conservative management approach might represent a desirable alternative. The aim of this study was to determine the natural history and outcome following the conservative management of 72 patients with unilateral vestibular schwannomas. This is a prospective cohort review of a previously published group of patients [Clin. Otolaryngol. (2000) 25, 28-39] with unilateral vestibular schwannoma that were initially analysed at our institution in 1998 [Walsh R.M., Bath A.P., Bance M.L. et al., Clin. Otolaryngol. (2000) 25, 28]. The mean duration of follow-up was 80 months (range 52-242 months). All the patients in the study underwent serial magnetic resonance imaging (MRI) for assessment of tumour growth. Patients were deemed to have failed conservative management if there was evidence of rapid radiological tumour growth and/or increasing signs and symptoms, which necessitated active intervention. The mean tumour growth rate for the entire group at the second review was 1 mm/year (range -0.84-9.65 mm/year). The mean growth rate for cerebellopontine angle tumours (1.3 mm/year) was significantly greater than that of internal auditory canal (IAC) tumours (0 mm/year) (P = 0.005). The majority of tumours (87.14%) grew <2 mm/year. There was significant tumour growth seen in 38.9%, no or insignificant growth in 41.7%, and negative growth in 19.4%. Twenty-three patients (32%) failed conservative management at the second review. There was no difference in the outcome of these failed patients in comparison with patients who underwent primary treatment without a period of conservative management. The mean growth rate of tumours in patients that failed conservative management (3.1 mm/year) was significantly greater than that in patients who did not fail (0.2 mm/year) (P < 0.001). No factors predictive of tumour growth or failure of conservative management were identified. Hearing deterioration with pure tone averages (0.5, 1, 2, 3 kHz) and speech discrimination scores occurred irrespective of tumour growth. This prospective study further emphasizes the role of conservative management in selected cases of vestibular schwannomas. Tumours in this study confined to the IAC typically demonstrated minimal or no growth on serial MRI scanning. Regular follow-up with interval scanning is mandatory in all patients.

Laparoscopic splenectomy for lymphoproliferative disease

BACKGROUND

Elective laparoscopic splenectomy (LS) achieves excellent results for benign hematologic diseases. The role of LS for hematologic malignancies is harder to define owing to associated splenomegaly and patient disease that may alter outcome.

METHODS

Retrospective review of single institution experience 1996 through 2002. To limit variability of disease processes, only patients with immune thrombocytopenic purpura (ITP) and lymphoproliferative disease (LPD) were studied.

RESULTS

A total of 211 LS have been performed, including 73 for LPD and 86 for ITP. Patients with LPD were significantly older, 61 vs 46 years p<0.001; male, 45 (62%) vs 33 (38%), p<0.001; and larger splenic weight, 680 vs 162 g, p<0.001. Fifty-nine patients (81%) with LPD were operated with standard LS with a conversion rate of 15%. Hand-assisted LS was performed in 14 patients (19%), and three were converted to open. Compared to ITP, patients with LPD had longer operative time, 148 vs 126 min, p<0001, and higher blood loss, 200 vs 100 cc, p = 0.004. There was one mortality (0.6%), and morbidity occurred in six patients (8%) with LPD and seven (8%) with ITP. The median length of stay was 3 days for LPD and 2 days for ITP, p = 0.03. Forty-six patients were principally operated for a diagnosis, and 27 (60%) were found to have lymphoma.

CONCLUSIONS

LS can be performed safely in patients with LPD, and when used judiciously with hand-assisted techniques can be performed with low conversion and morbidity rates. Splenectomy plays an important role in establishing the diagnosis of lymphoma in LPD.

Imaging for the diagnosis and staging of periampullary carcinomas

Multiple imaging modalities are available for investigating patients with a suspected periampullary neoplasm. The relative utility of each imaging modality is discussed regarding its role in diagnosis and staging. A general imaging approach to patients with a distal biliary obstruction also is presented.

Determination of intact splenic weight based on morcellated weight

BACKGROUND

Comparisons of splenic size based on splenic weight are difficult after laparoscopic splenectomy, which results in a morcellated specimen. We report the results of a direct comparison between morcellated and intact splenic weights.

METHODS

Porcine spleens were harvested via a midline laparotomy, and an intact splenic weight was obtained, which served as the control. The spleen then was placed into an impermeable retrieval bag and returned to the peritoneal cavity. A separate 10-mm incision was made and the spleen mechanically morcellated with a uterine forceps. This design most faithfully recreates the morcellation process during laparoscopic splenectomy in humans. The aggregate weight of the fragments was compared with intact splenic weight.

RESULTS

Intact and morcellated weights were obtained from 58 porcine spleens. The mean intact splenic weight was 145 g, and the mean morcellated weight was 78 g. For a given morcellated weight achieved at laparoscopic splenectomy, an estimated intact weight can be determined by the following formula: intact weight (g) = morcellated weight (g) x 1.34 + 45.

CONCLUSIONS

On the basis of our calculations, a normal spleen weighing 150 g would have a mean morcellated weight of 78 g, and splenomegaly (intact spleen weighing 250 g or more) would be defined by a morcellated weight exceeding 153 g.

Recurrence after laparoscopic ventral hernia repair

BACKGROUND

Although the early results of laparoscopic ventral hernia repair have shown a low recurrence rate, there is a paucity of long-term data. This study reviews a single institution's experience with laparoscopic ventral hernia repair (LVHR).

METHODS

We carried out a retrospective analysis of all LVHR performed at the Cleveland Clinic Foundation from January 1996 to March 2001. Recurrence rates were determined by physical exam or telephone follow-up. Factors predictive of recurrence were determined using Cox regression.

RESULTS

Of 100 ventral hernias completed laparoscopically, 96 were available for long-term follow-up (average, 30 months; range 4-65). There were no deaths and major morbidity occurred in seven patients. Recurrences were identified in 17 patients. Nine recurrences occurred in the 1st postoperative year; however, hernia recurrence continued throughout the period of follow-up. Multivariate analysis showed that a prior failed hernia repair was associated with a more likely chance of another recurrence (65% vs 35%, odds ratio (OR) 3.6; p = 0.05) and that an increased estimated blood loss (106 cc vs 51 cc, OR 1.03; p = 0.005) predicted recurrence. Other variables, including body mass index (BMI) (32 vs 31 kg/m2, p = 0.38), defect size (115 cm2 vs 91 cm2; p = 0.23), size of mesh (468 cm2 vs 334 cm2, p = 0.19), type of mesh (p = 0.62), and mesh fixation (p = 0.99), did not predict recurrence. An additional 14 cases required conversion to an open operation, and seven of these cases (50%) had recurrence on long-term follow-up.

CONCLUSION

Although LVHR remains the preferred method of hernia repair at our institution, this study documents a higher recurrence rate than many other short-term series. There results underscore the importance of long-term follow-up in assessing hernia surgery outcome.

Application of the U and gamma' models in binary sweet taste mixtures

The U and Gamma' models of sensory interactions, successfully applied in olfaction for several years, are tested here using data from published studies on sweetness. The models are subsequently tested on new data obtained in studies of binary mixtures of four sodium sulfamates. The U model allows for the estimation of a global interaction, whereas the Gamma' model allows for the distinction between that which is due to an intrinsic interaction in the mixture itself and that which may be due to the power function exponents in the mixture. The models give satisfactory predictions for observed phenomena of sweet taste suppression, synergism or pure additivity. Additionally, they appear to be more suitable than other models recently applied in taste, particularly the equiratio model. Application of the models to the sulfamate mixtures, reveals additivity for sodium cyclohexylsulfamate (cyclamate)/potassium cyclohexylsulfamate and sodium cyclohexylsulfamate/sodium exo-2-norbornylsulfamate, respectively; whereas for sodium cyclohexylsulfamate/sodium 3-bromophenylsulfamate, the models revealed a slight hypo addition which is simply due to the dissimilarity values of the power function exponents of the components.