The relationship between the severity of intellectual and developmental disabilities (IDDs) in adults with IDDs and eating and drinking problems and nutritional status

BACKGROUND

Adults with intellectual and developmental disabilities (IDDs) experience eating, drinking and swallowing problems, such as chewing problems, choking, gagging, coughing during eating, aspiration and rumination syndrome, which may lead to poor nutritional status. This study aimed to determine the relationship between IDD levels, eating, drinking and swallowing problems and nutritional status in adults with IDDs.

METHODS

The sample consisted of 71 participants (37 men and 34 women) with a mean age of 22.5 ± 7 years (range 18-60 years). Professionals classified intellectual disability as mild, moderate or severe. The Screening Tool of Feeding Problems scale was applied to the caregivers of adults with IDDs to identify eating, drinking and swallowing problems. Dietary intake was assessed using a 24-h dietary recall and a food and nutrition photograph catalogue. The researchers measured body weight, height and middle upper arm circumference. Body mass index was calculated. Four body mass index categories were determined: underweight (<18.5 kg/m2 ), normal weight (18.5-24.9 kg/m2 ), overweight (25.0-29.9 kg/m2 ) and obese (≥30 kg/m2 ). Chi-squared tests were used to detect the relationship between IDD levels and eating and drinking problems, and analysis of variance tests were conducted to detect the relationship between IDD levels with anthropometric measurements and dietary intake.

RESULTS

Participants had mild (42.3%; n = 30), moderate (29.6%; n = 21) or severe IDD (28.2%; n = 20). They were underweight (12.7%; n = 9), normal weight (59.2%; n = 42) or overweight and/or obese (28.2%; n = 20). Participants with severe IDD had significantly higher Screening Tool of Feeding Problems 'nutrition-related behaviour' and 'eating and drinking skill deficit problem' sub-scale scores than those with mild IDD. However, the groups had no significant difference in 'food refusal and selectivity' sub-scale scores. Participants with severe IDD also had anorexia prevalence similar to those with mild IDD. The groups did not significantly differ in anthropometric measurements, daily energy intake and macronutrient and micronutrient intake.

CONCLUSIONS

While adults with severe IDD had more eating and drinking skill deficits (e.g. chewing problems and independent eating difficulties) and nutrition-related behaviour problems than those with mild IDD, the eating, drinking and swallowing problems, which may critically affect their food intake, were similar to adults with mild IDD. The anthropometric measurements and energy and nutrient intakes of adults with severe IDD were not significantly different from those with mild IDD consistently. Findings indicate that nutritional deficiencies and nutritional behaviour problems may be avoidable in adults with IDDs.

Solid pseudopapillary neoplasms of the pancreas in childhood and adolescence-an analysis of the German Registry for Rare Pediatric Tumors (STEP)

Solid pseudopapillary neoplasms (SPNs) are the most common entity among pediatric pancreatic tumors. Still, these are rare tumors with an annual incidence of 0.1-0.2/1,000,000, and little is known about their optimal treatment. This analysis aimed to increase knowledge about the occurrence and treatment strategies of SPN in childhood. Data regarding diagnostics, treatment, and outcome of children aged 0-18 years with SPN recorded in the German Registry for Rare Pediatric Tumors (STEP) were analyzed. Thirty-eight patients were identified with a median age of 14.5 years at diagnosis (range: 8-18) and a female preponderance (81.6%). The most frequent location of the tumor was the pancreatic tail. In histopathological and immunohistochemical examination, pseudopapillary, solid, and cystic lesions as well as expression of beta-catenin, progesterone receptors, and cyclin D1 were the most common findings. All patients underwent surgical resection. Most patients underwent open resection, predominantly tail resection for tumors in the tail region and pylorus-preserving pancreaticoduodenectomy for tumors in the head region. The main postoperative sequela was exogenous pancreatic insufficiency (23.7%), especially with SPN in the pancreatic head. No recurrence occurred during follow-up, although two patients underwent resection with microscopic residue.

CONCLUSION

SPN of the pancreas in childhood are low-grade malignancies with usually favorable treatment outcomes. However, therapy can lead to relevant long-term sequelae. To prevent recurrence, complete surgical resection is recommended, sparing as much healthy pancreatic tissue as possible. Interdisciplinary collaboration between specialists is essential to optimize treatment. Molecular genetic analysis of these tumors could improve understanding of their genesis.

WHAT IS KNOWN

• Solid pseudopapillary neoplasms (SPNs) of the pancreas are very rare tumors in childhood. • Little is known about tumorigenesis, and there are no specific guidelines for treatment and follow-up in pediatric patients.

WHAT IS NEW

• Characteristics, treatment, and outcome were comprehensively assessed in a large cohort of pediatric patients with SPN. • We propose recommendations for diagnosis, treatment, and follow-up of children with SPN, based on our analysis and considering published experience.

Recent Advances in Sharing Standardized Composite Structure Design and Manufacturing Information

Composite structures have been developed and used in the aerospace, automobile, sports, and marine industries since the early 1940s. Compared to conventional metallic structures, newer high-performance composite structures provide benefits such as decreased weight and reduced energy consumption. An international standards subcommittee on industrial automation systems and integration has developed and implemented a standard, ISO 10303-209, for sharing the manufacturing information for these complex composite structures. This standard is considered essential for improving the design, analysis, and manufacturing productivity of composite structures, and for enabling the long-term data retention necessary to support the composite structures throughout the lifetime of the products that use them. This paper describes recent advances that led to the development of ISO 10303-209 data models for composite structural shape and composition. The paper also reports the status of ongoing implementation efforts, including efforts to use this standard to support long-term data retention. The varied usage scenarios have motivated several areas for future improvement such as full three-dimensional representation and the efficient, cost-effective visualization of composite structural parts. Issues and their proposed solutions, along with their anticipated impacts on the design, analysis, manufacturing, and long-term support of composite structures are also discussed.

Detection of Cellular Target Engagement for Small-Molecule Modulators of Striatal-Enriched Protein Tyrosine Phosphatase (STEP)

Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific enzyme that regulates the signaling molecules that control synaptic plasticity and neuronal function. Dysregulation of STEP is linked to the pathophysiology of Alzheimer's disease and other neuropsychiatric disorders. Experimental results from neurological deficit disease models suggest that the modulation of STEP could be beneficial in a number of these disorders. This prompted our work to identify small-molecule modulators of STEP to provide the foundation of a drug discovery program. As a component of our testing funnel to identify small-molecule STEP inhibitors, we have developed a cellular target engagement assay that can identify compounds that interact with STEP46. We provide a comprehensive protocol to enable the use of this miniaturized assay, and we demonstrate its utility to benchmark the binding of newly discovered compounds.

Fbxo45-mediated NP-STEP46 degradation via K6-linked ubiquitination sustains ERK activity in lung cancer

Lung cancer is one of the most threatening malignant tumors to human health. Epidermal growth factor receptor (EGFR)‐targeted therapy is a common and essential means for the clinical treatment of lung cancer. However, drug resistance has always affected the therapeutic effect and survival rate in non‐small cell lung cancer (NSCLC). Tumor heterogeneity is a significant reason, yielding various drug resistance mechanisms, such as EGFR‐dependent or ‐independent extracellular signal‐regulated kinase 1 and/or 2 (ERK1/2) activation in NSCLC. To examine whether this aberrant activation of ERK1/2 is related to the loss of function of its specific phosphatase, a series of in vitro and in vivo assays were performed. We found that F‐box/SPRY domain‐containing protein 1 (Fbxo45) induces ubiquitination of NP‐STEP₄₆, an active form of striatal‐enriched protein tyrosine phosphatase, with a K6‐linked poly‐ubiquitin chain. This ubiquitination led to proteasome degradation in the nucleus, which then sustains the aberrant level of phosphorylated‐ERK (pERK) and promotes tumor growth of NSCLC. Fbxo45 silencing can significantly inhibit cell proliferation and tumor growth. Moreover, NSCLC cells with silenced Fbxo45 showed great sensitivity to the EGFR tyrosine kinase inhibitor (TKI) afatinib. Here, we first report this critical pERK maintenance mechanism, which might be independent of the upstream kinase activity in NSCLC. We propose that inhibiting Fbxo45 may combat the issue of drug resistance in NSCLC patients, especially combining with EGFR‐TKI therapy.

Pharmacological inhibition of STriatal-Enriched protein tyrosine Phosphatase by TC-2153 reduces hippocampal excitability and seizure propensity

OBJECTIVE

STriatal-Enriched protein tyrosine Phosphatase (STEP) is a brain-specific tyrosine phosphatase. Membrane-bound STEP61 is the only isoform expressed in hippocampus and cortex. Genetic deletion of STEP enhances excitatory synaptic currents and long-term potentiation in the hippocampus. However, whether STEP61 affects seizure susceptibility is unclear. Here we investigated the effects of STEP inhibitor TC-2153 on seizure propensity in a murine model displaying kainic acid (KA)-induced status epilepticus and its effect on hippocampal excitability.

METHODS

Adult male and female C57BL/6J mice received intraperitoneal injection of either vehicle (2.8% dimethylsulfoxide [DMSO] in saline) or TC-2153 (10 mg/kg) and then either saline or KA (30 mg/kg) 3 h later before being monitored for behavioral seizures. A subset of female mice was ovariectomized (OVX). Acute hippocampal slices from Thy1-GCaMP6s mice were treated with either DMSO or TC-2153 (10 μM) for 1 h, and then incubated in artificial cerebrospinal fluid (ACSF) and potassium chloride (15 mM) for 2 min prior to live calcium imaging. Pyramidal neurons in dissociated rat hippocampal culture (DIV 8-10) were pre-treated with DMSO or TC-2153 (10 µM) for 1 h before whole-cell patch-clamp recording.

RESULTS

TC-2153 treatment significantly reduced KA-induced seizure severity, with greater trend seen in female mice. OVX abolished this TC-2153-induced decrease in seizure severity in female mice. TC-2153 application significantly decreased overall excitability of acute hippocampal slices from both sexes. Surprisingly, TC-2153 treatment hyperpolarized resting membrane potential and decreased firing rate, sag voltage, and hyperpolarization-induced current (Ih ) of cultured hippocampal pyramidal neurons.

SIGNIFICANCE

This study is the first to demonstrate that pharmacological inhibition of STEP with TC-2153 decreases seizure severity and hippocampal activity in both sexes, and dampens hippocampal neuronal excitability and Ih . We propose that the antiseizure effects of TC-2153 are mediated by its unexpected action on suppressing neuronal intrinsic excitability.

Transcutaneous auricular vagus nerve stimulation (taVNS) given for poor feeding in at-risk infants also improves their motor abilities

PURPOSE

Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation technique that may improve oromotor skills when paired with feeding in at-risk infants, but effects on other motor function and how motor function relates to white matter (WM) microstructure are unknown.

METHODS

In this prospective study, infants failing oral feeds and slated for gastrostomy tube (G-tube) placement received taVNS paired with bottle feeding daily for 2-3 weeks. The effects of taVNS-paired feeding on general and specific head movements were investigated using the Specific Test of Early infant motor Performance (STEP) and diffusion MRI obtained before and after taVNS treatment. Scores between and within groups (taVNS responders, attained full oral feeds; non-responders, received G-tubes) were compared.

RESULTS

Performance on head movement items improved significantly in responders but not in non-responders (p < 0.05). Total STEP scores were significantly higher in responders after taVNS treatment than non-responders (p = 0.04). One STEP item, rolling by arm, was associated with significantly greater change in WM tract microstructure (p < 0.05) in the responders.

CONCLUSION

These results suggest that pairing feeding with taVNS may affect specific head and neck movements to a greater extent in infants who are able to attain full oral feeds.

Reelin Regulates Neuronal Excitability through Striatal-Enriched Protein Tyrosine Phosphatase (STEP61) and Calcium Permeable AMPARs in an NMDAR-Dependent Manner

Alzheimer's disease (AD) is a progressive neurodegenerative disease marked by the accumulation of amyloid-β (Aβ) plaques and neurofibrillary tangles. Aβ oligomers cause synaptic dysfunction early in AD by enhancing long-term depression (LTD; a paradigm for forgetfulness) via metabotropic glutamate receptor (mGluR)-dependent regulation of striatal-enriched tyrosine phosphatase (STEP61). Reelin is a neuromodulator that signals through ApoE (apolipoprotein E) receptors to protect the synapse against Aβ toxicity (Durakoglugil et al., 2009) Reelin signaling is impaired by ApoE4, the most important genetic risk factor for AD, and Aβ-oligomers activate metabotropic glutamate receptors (Renner et al., 2010). We therefore asked whether Reelin might also affect mGluR-LTD. To this end, we induced chemical mGluR-LTD using DHPG (Dihydroxyphenylglycine), a selective mGluR5 agonist. We found that exogenous Reelin reduces the DHPG-induced increase in STEP61, prevents the dephosphorylation of GluA2, and concomitantly blocks mGluR-mediated LTD. By contrast, Reelin deficiency increased expression of Ca2+-permeable GluA2-lacking AMPA receptors along with higher STEP61 levels, resulting in occlusion of DHPG-induced LTD in hippocampal CA1 neurons. We propose a model in which Reelin modulates local protein synthesis as well as AMPA receptor subunit composition through modulation of mGluR-mediated signaling with implications for memory consolidation or neurodegeneration.SIGNIFICANCE STATEMENT Reelin is an important neuromodulator, which in the adult brain controls synaptic plasticity and protects against neurodegeneration. Amyloid-β has been shown to use mGluRs to induce synaptic depression through endocytosis of NMDA and AMPA receptors, a mechanism referred to as LTD, a paradigm of forgetfulness. Our results show that Reelin regulates the phosphatase STEP, which plays an important role in neurodegeneration, as well as the expression of calcium-permeable AMPA receptors, which play a role in memory formation. These data suggest that Reelin uses mGluR LTD pathways to regulate memory formation as well as neurodegeneration.

[Decrease in the Activity of Striatal-Enriched Protein-Tyrosine-Phosphatase (STEP) in the Brain of Danio rerio Treated with p-Chlorophenylalanine and Pargyline]

Fundamental neurophysiological processes are often studied using Danio rerio fish as a model. A selective inhibitor of striatal-enriched protein tyrosine phosphatase (STEP) reduces serotonin metabolism in the D. rerio brain. Both STEP and serotonin are involved in the development of neurodegenerative behavioral disorders. Reduction or elevation of the serotonin level in the brain of mice caused by the administration of p-chlorophenylalanine or pargyline, respectively, results in a decrease in the level of ptpn5 mRNA in the striatum, ptpn5 being the gene encoding STEP. However, it has not been established whether this occurs in other organisms. We studied the effect of inhibitors of synthesis (p-chlorophenylalanine) and degradation (pargyline) of serotonin on the expression of the ptpn5 gene and the activity of STEP in the brain of D. rerio. The fish were placed in water containing p-chlorophenylalanine (2 mg/L) or pargyline (0.5 mg/L) for 72 hours, and control subjects were kept in aquarium water. The p-chlorophenylalanine treatment decreased the serotonin level in the brain fourfold, whereas pargyline increased the level of this transmitter sixfold. Both p-chlorophenylalanine and pargyline decrease STEP activity in the D. rerio brain, without affecting the level of the ptpn5 mRNA gene. Thus, interaction between STEP and the serotonin system is observed in both mammals and fish, which indicates the similarity of the regulation processes in vertebrates.

Tyrosine phosphatase STEP is a key regulator of glutamate-induced prostaglandin E2 release from neurons

The neuron-specific tyrosine phosphatase striatal-enriched phosphatase (STEP) is emerging as a key regulator of excitotoxicity, which is involved in the pathogenesis of both acute and chronic neurological diseases. However, the intracellular mechanisms that are regulated by STEP to confer neuroprotection against excitotoxic insults are not well understood. The present study investigates the role of STEP in regulating neuronal release of the proinflammatory prostanoid prostaglandin E₂ (PGE₂), which is associated with a wide range of pathological conditions. The findings show that glutamate-mediated activation of the N-methyl-D-aspartic acid receptor in STEP-deficient neurons leads to rapid and sustained increase in the phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), a signaling molecule involved in the production of inflammatory mediators. Such sustained p38 MAPK activation increases the activity of cytosolic phospholipase A₂, which catalyzes the release of arachidonic acid, the initial substrate for PGE₂ biosynthesis. Sustained p38 MAPK activation also induces nuclear factor-κB–mediated increase in expression of cyclooxygenase-2 that is involved in the conversion of arachidonic acid to prostanoids, resulting in enhanced biosynthesis and release of PGE₂ from neurons. Restoration of STEP function with a STEP mimetic (TAT-STEP-myc peptide) significantly decreases the activation of p38 MAPK–mediated cytosolic phospholipase A₂/cyclooxygenase-2/PGE₂ signaling cascade. This study identifies an important mechanism involved in the neuronal release of the proinflammatory mediator PGE₂ after excitotoxic insult and highlights for the first time the immunomodulatory ability of a neuronal tyrosine phosphatase.

The Implication of STEP in Synaptic Plasticity and Cognitive Impairments in Alzheimer's Disease and Other Neurological Disorders

STriatal-Enriched protein tyrosine Phosphatase (STEP) is a tyrosine phosphatase that has been implicated in Alzheimer’s disease (AD), the most common form of dementia, and many other neurological diseases. The protein level and activity of STEP have been found to be elevated in most of these disorders, and specifically in AD as a result of dysregulation of different pathways including PP2B/DARPP32/PP1, PKA as well as impairments of both proteasomal and lysosomal systems. The upregulation in STEP leads to increased binding to, and dephosphorylation of, its substrates which are mainly found to be synaptic plasticity and thus learning and memory related proteins. These proteins include kinases like Fyn, Pyk2, ERK1/2 and both NMDA and AMPA receptor subunits GluN2B and GluA2. The dephosphorylation of these molecules results in inactivation of these kinases and internalization of NMDA and AMPA receptor complexes leading to synapse loss and cognitive impairments. In this study, we aim to review STEP regulation and its implications in AD as well as other neurological disorders and then summarize data on targeting STEP as therapeutic strategy in these diseases.

Repeat serial transverse enteroplasty leads to reduction in parenteral nutrition in children with short bowel syndrome

BACKGROUND/PURPOSE

Following a serial transverse enteroplasty (STEP) procedure some children develop redilation of the small intestine leading to impaired enteral tolerance and inability to wean parenteral nutrition (PN). The benefit of a second STEP procedure (2STEP) has been controversial.

METHODS

We performed a retrospective review of our experience (2008-2018) performing 2STEP, with comparative analysis of nutritional outcomes pre- and postsurgery.

RESULTS

During this period 2STEP was performed in 23 patients (13 F:10 M) at a median (25%-75%) age of 2.2 (1.2-3.6) years. Median intestinal length was 68 (40-105) cm before and 85 (40-128) cm after 2STEP. Leading up to 2STEP, PN provided almost 75% of estimated calorie needs. By 24 weeks following 2STEP drops in mean PN percent approached statistical significance (p = 0.07) and at most recent follow up the mean PN percentage was statistically better than at the time of operation or 4 weeks prior to 2STEP, and was nearly significant compared with 12 weeks (p = 0.07) and 24 weeks (p = 0.06) prior. Thirteen children were completely off parenteral support.

CONCLUSION

When small intestine redilation occurs following a STEP procedure and where PN cannot otherwise be weaned we believe these data support performing a 2STEP. We cannot predict preoperatively which children will ultimately benefit.

LEVEL OF EVIDENCE

3 (retrospective comparative study).

Regulation of post-ischemic inflammatory response: A novel function of the neuronal tyrosine phosphatase STEP

The neuron-specific tyrosine phosphatase STEP is emerging as a key neuroprotectant against acute ischemic stroke. However, it remains unclear how STEP impacts the outcome of stroke. We find that the exacerbation of ischemic brain injury in STEP deficient mice involves an early onset and sustained activation of neuronal p38 mitogen activated protein kinase, a substrate of STEP. This leads to rapid increase in the expression of neuronal cyclooxygenase-2 and synthesis of prostaglandin E₂, causing change in microglial morphology to an amoeboid activated state, activation of matrix metalloproteinase-9, cleavage of tight junction proteins and extravasation of IgG into the ischemic brain. Restoration of STEP signaling with intravenous administration of a STEP-derived peptide mimetic reduces the post-ischemic inflammatory response and attenuates brain injury. The findings identify a unique role of STEP in regulating post-ischemic neuroinflammation and further emphasizes the therapeutic potential of the STEP-mimetic in neurological disorders where inflammation contributes to brain damage.

STEP inhibition prevents Aβ-mediated damage in dendritic complexity and spine density in Alzheimer's disease

Loss of dendritic spines and decline of cognitive function are hallmarks of patients with Alzheimer's disease (AD). Previous studies have shown that AD pathophysiology involves increased expression of a central nervous system-enriched protein tyrosine phosphatase called STEP (STriatal-Enriched protein tyrosine Phosphatase). STEP opposes the development of synaptic strengthening by dephosphorylating substrates, including GluN2B, Pyk2, and ERK1/2. Genetic reduction of STEP as well as pharmacological inhibition of STEP improve cognitive function and hippocampal memory in the 3×Tg-AD mouse model. Here, we show that the improved cognitive function is accompanied by an increase in synaptic connectivity in cell cultures as well as in the triple transgenic AD mouse model, further highlighting the potential of STEP inhibitors as a therapeutic agent.

STEP improves long-term survival for pediatric short bowel syndrome patients: A Markov decision analysis

INTRODUCTION

Increasingly, for pediatric patients with short bowel syndrome (SBS), intestinal lengthening procedures such as serial transverse enteroplasty (STEP) are being offered with the hope of improving patients' chances for achieving enteral autonomy. However, it remains unclear to what extent STEP reduces the long-term need for intestinal transplant or improves survival.

METHODS

Based on existing literature, a decision analytic Markov state transition model was created to simulate the life of 1,000 pediatric SBS patients. Two simulations were modeled: 1) No STEP: patients were listed for transplant once medical management failed and 2) STEP: patients underwent STEP therapy and subsequent transplant listing if enteral autonomy was not achieved. Sensitivity analysis of small bowel length and anatomy was completed. Base case patients were defined as neonates with a small bowel length of 30cm.

RESULTS

For base case patients with an ostomy and a NEC SBS etiology, STEP was associated with increased rates of enteral autonomy after 10 years for patients with an ICV (53.9% [STEP] vs. 51.1% [No STEP]) and without an ICV (43.4% [STEP] vs. 36.3% [No STEP]). Transplantation rates were also reduced following STEP therapy for both ICV (17.5% [STEP] vs. 18.2% [No STEP]) and non-ICV patients (20.2% [STEP] vs. 22.1% [No STEP]). 10-year survival was the highest in the (+) STEP and (+) ICV group (85.4%) and lowest in the (-) STEP and (-) ICV group (83.3%).

CONCLUSIONS

For SBS patients, according to our model, STEP increases rates of enteral autonomy, reduces need for intestinal transplantation, and improves long-term survival.

TYPE OF STUDY

Economic/Decision Analysis or Modeling Studies LEVEL OF EVIDENCE: Level III.

[Pargyline and р-Chlorophenylalanine Decrease Expression of Ptpn5 Encoding Striatal-Enriched Protein Tyrosine Phosphatase (STEP) in the Mouse Striatum]

Striatal-enriched protein tyrosine phosphatase (STEP), which was initially identified in the striatum, is encoded by the Ptpn5 gene and is expressed in neurons of various structures of the brain. STEP is involved in regulating neuroplasticity, and its expression abnormalities are associated with human neurodegenerative disorders. The STEP inhibitor 8-trifluoromethyl-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride (TC-2153) has been shown to affect the serotoninergic system of the brain. However, the influence of the serotoninergic system on the STEP regulation has not been studied yet. The aim of the study was to investigate how pharmacologically induced changes in the brain serotonin (5-HT) level affect Ptpn5 expression and STEP activity in adult male C57BL/6J mice. To modulate the 5-HT level in the brain, the 5-HT synthesis inhibitor p-chlorophenylalanine or 5-HT degradation inhibitor pargyline was administered intraperitoneally for three successive days. Changes in 5-HT concentration in the brain were assayed using high-performance liquid chromatography. The STEP activity was determined spectrophotometrically in the supernatant by the rate of p-nitrophenyl phosphate dephosphorylation in the absence and presence of the selective STEP inhibitor TC-2153. The Ptpn5 mRNA level was determined using quantitative RT-PCR. The Ptpn5 expression level in the striatum was three times higher than in the cortex and hippocampus. Both increases and decreases in brain 5-HT were for the first time associated with a decrease in Ptpn5 mRNA in the striatum. STEP activity in the striatum and cortex was significantly higher than in the hippocampus. However, p-chlorophenylalanine and pargyline did not affect the STEP activity in the brain structures tested. Thus, a new method was proposed to study the STEP activity in the brain and p-chlorophenylalanine and pargyline were shown to decrease Ptpn5 expression in the striatum in mice.

Inhibition of striatal-enriched protein tyrosine phosphatase (STEP) activity reverses behavioral deficits in a rodent model of autism

Autism spectrum disorders (ASDs) are highly prevalent childhood illnesses characterized by impairments in communication, social behavior, and repetitive behaviors. Studies have found aberrant synaptic plasticity and neuronal connectivity during the early stages of brain development and have suggested that these contribute to an increased risk for ASD. STEP is a protein tyrosine phosphatase that regulates synaptic plasticity and is implicated in several cognitive disorders. Here we test the hypothesis that STEP may contribute to some of the aberrant behaviors present in the VPA-induced mouse model of ASD. In utero VPA exposure of pregnant dams results in autistic-like behavior in the pups, which is associated with a significant increase in the STEP expression in the prefrontal cortex. The elevated STEP protein levels are correlated with increased dephosphorylation of STEP substrates GluN2B, Pyk2 and ERK, suggesting upregulated STEP activity. Moreover, pharmacological inhibition of STEP rescues the sociability, repetitive and abnormal anxiety phenotypes commonly associated with ASD. These data suggest that STEP may play a role in the VPA model of ASD and STEP inhibition may have a potential therapeutic benefit in this model.

Regulation of glutamate receptors by striatal-enriched tyrosine phosphatase 61 (STEP61 )

Phosphorylation regulates glutamate receptor trafficking. The cytosolic C-terminal domains of both NMDA receptors (NMDARs) and AMPA receptors (AMPARs) have distinct motifs, which are substrates for serine/threonine and tyrosine phosphorylation. Decades of research have shown how phosphorylation of glutamate receptors mediates protein binding and receptor trafficking, ultimately controlling synaptic transmission and plasticity. STEP is a protein tyrosine phosphatase (also known as PTPN5), with several isoforms resulting from alternative splicing. Targets of STEP include a variety of important synaptic substrates, among which are the tyrosine kinase Fyn and glutamate receptors. In particular, STEP₆₁ , the longest isoform, dephosphorylates the NMDAR subunit GluN2B and strongly regulates the expression of NMDARs at synapses. This interplay between STEP, Fyn and GluN2B-containing NMDARs has been characterized by multiple groups. More recently, STEP₆₁ was shown to bind to AMPARs in a subunit-specific manner and differentially regulate synaptic NMDARs and AMPARs. Because of its many effects on synaptic proteins, STEP has been implicated in regulating excitatory synapses during plasticity and playing a role in synaptic dysfunction in a variety of neurological disorders. In this review, we will highlight the ways in which STEP₆₁ differentially regulates NMDARs and AMPARs, as well as its role in plasticity and disease.

Auto-assessment tools for mechanical computer aided design education

Traditionally Computer Aided Design (CAD) courses have been carried out in computer classrooms requiring great amount of teaching personnel. Assessment of students' modeling exercises has been both time consuming and error prone. Utilization of the teaching resources could clearly benefit from online auto-assessment. The auto-assessment tools are widely in use in programming and language courses, but suitable tools for assessing 3D models used in CAD are lacking. This paper presents two new online auto-assessment tools to support the development of both command (“what steps are needed to create this shape?”) and strategic (“how should I model this shape?”) knowledge while learning CAD. The first tool is based on neutral file format (in this case STEP) and can recognize surface differences between student's model and reference model. This tool can assess student's skill to create certain predefined shape (i.e. command knowledge). The second auto-assessment tool utilizes commercial CAD software's API (Application Programming Interface) to test how student's model behaves when modeling parameters are changed. This tool assess student's capabilities to build and design a CAD model's design intent (i.e. strategic knowledge). Developed tools were tested on three mechanical engineering courses. This paper presents both the tools and the feedback received from the students and teachers. Overall, the auto-assessment tools functioned well and feedback from both students and teachers were positive. The most appreciated tool functionality was time and place independent submission and assessment of exercise works. These new tools able focusing teachers' workload from checking the basic exercises to guiding the learning process.

A peptide mimetic of tyrosine phosphatase STEP as a potential therapeutic agent for treatment of cerebral ischemic stroke

Extensive research over the last two decades has advanced our understanding of the pathophysiology of ischemic stroke. However, current pharmacologic therapies are still limited to rapid reperfusion using thrombolytic agents, and neuroprotective approaches that can reduce the consequences of ischemic and reperfusion injury, are still not available. To bridge this gap, we have evaluated the long-term efficacy and therapeutic time window of a novel peptide-based neuroprotectant TAT-STEP, derived from the brain-enriched and neuron-specific tyrosine phosphatase STEP. Using a rat model of transient middle cerebral artery occlusion (90 min), we show that a single intravenous administration of the peptide at the onset of reperfusion (early) or 6 h after the onset of the insult (delayed) reduces mortality rate. In the surviving rats, MRI scans of the brain at days 1, 14 and 28 after the insult show significant reduction in infarct size and improvement of structural integrity within the infarcted area following peptide treatment, regardless of the time of administration. Behavioral assessments show significant improvement in normal gait, motor coordination, sensory motor function and spatial memory following early or delayed peptide treatment. The study establishes for the first time the therapeutic potential of a tyrosine phosphatase in ischemic brain injury.

The STEP61 interactome reveals subunit-specific AMPA receptor binding and synaptic regulation

Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific protein phosphatase that regulates a variety of synaptic proteins, including NMDA receptors (NAMDRs). To better understand STEP's effect on other receptors, we used mass spectrometry to identify the STEP₆₁ interactome. We identified a number of known interactors, but also ones including the GluA2 subunit of AMPA receptors (AMPARs). We show that STEP₆₁ binds to the C termini of GluA2 and GluA3 as well as endogenous AMPARs in hippocampus. The synaptic expression of GluA2 and GluA3 is increased in STEP-KO mouse brain, and STEP knockdown in hippocampal slices increases AMPAR-mediated synaptic currents. Interestingly, STEP₆₁ overexpression reduces the synaptic expression and synaptic currents of both AMPARs and NMDARs. Furthermore, STEP₆₁ regulation of synaptic AMPARs is mediated by lysosomal degradation. Thus, we report a comprehensive list of STEP₆₁ binding partners, including AMPARs, and reveal a central role for STEP₆₁ in differentially organizing synaptic AMPARs and NMDARs.

Simultaneous Serial Transverse Enteroplasty (STEP) in Size Mismatch Small Bowel Transplantations

BACKGROUND

Small bowel transplantation (SBTX) in children receiving larger grafts from adults can be challenging because of size mismatch. The aim of the present study was to assess whether a simultaneous serial transverse enteroplasty (STEP) can address the problem of size mismatch.

METHODS

Three different size ratio groups between donors and recipients were compared in a porcine model with a 14-day follow-up. The groups were size matched, size mismatched (1:3.8 weight ratio), and size mismatched + STEP (each n = 8).

RESULTS

It was technically feasible to simultaneously perform a STEP and SBTX of a mismatched intestinal segment. The postoperative clinical course was uneventful. No signs of bleeding, leakage, stenosis, or ileus were observed and the intestinal segment was well perfused at relaparotomy. Body weight decreased in all groups, but the percentage decrease was lowest in the mismatched + STEP group. Vital enterocyte masses were similar in all the groups (citrulline levels) and the nutritional status was best in the STEP group (transferrin levels, p = 0.04).

CONCLUSIONS

We have demonstrated that a simultaneous STEP and SBTX procedure is technically feasible and clinically useful in overcoming the challenges associated with size mismatched SBTX. Our short-term findings justify further investigation in a larger series to elucidate the long-term outcomes of this procedure.

Surveillance Training for Ebola Preparedness in Côte d'Ivoire, Guinea-Bissau, Senegal, and Mali

The 2014–2015 epidemic of Ebola virus disease in West Africa primarily affected Guinea, Liberia, and Sierra Leone. Several countries, including Mali, Nigeria, and Senegal, experienced Ebola importations. Realizing the importance of a trained field epidemiology workforce in neighboring countries to respond to Ebola importations, the Centers for Disease Control and Prevention Field Epidemiology Training Program unit implemented the Surveillance Training for Ebola Preparedness (STEP) initiative. STEP was a mentored, competency-based initiative to rapidly build up surveillance capacity along the borders of the at-risk neighboring countries Côte d’Ivoire, Mali, Senegal, and Guinea-Bissau. The target audience was district surveillance officers. STEP was delivered to 185 participants from 72 health units (districts or regions). Timeliness of reporting and the quality of surveillance analyses improved 3 months after training. STEP demonstrated that mentored, competency-based training, where learners attain competencies while delivering essential public health services, can be successfully implemented in an emergency response setting.

Intra-prelimbic cortical inhibition of striatal-enriched tyrosine phosphatase suppresses cocaine seeking in rats

Cocaine self-administration in rats results in dysfunctional neuroadaptations in the prelimbic (PrL) cortex during early abstinence. Central to these adaptations is decreased phospho-extracellular signal-regulated kinase (p-ERK), which plays a key role in cocaine seeking. Normalizing ERK phosphorylation in the PrL cortex immediately after cocaine self-administration decreases subsequent cocaine seeking. The disturbance in ERK phosphorylation is accompanied by decreased phosphorylation of striatal-enriched protein tyrosine phosphatase (STEP), indicating increased STEP activity. STEP is a well-recognized ERK phosphatase but whether STEP activation during early abstinence mediates the decrease in p-ERK and is involved in relapse is unknown. Here, we show that a single intra-PrL cortical microinfusion of the selective STEP inhibitor, TC-2153, immediately after self-administration suppressed post-abstinence context-induced relapse under extinction conditions and cue-induced reinstatement, but not cocaine prime-induced drug seeking or sucrose seeking. Moreover, an intra-PrL cortical TC-2153 microinfusion immediately after self-administration prevented the cocaine-induced decrease in p-ERK within the PrL cortex during early abstinence. Interestingly, a systemic TC-2153 injection at the same timepoint failed to suppress post-abstinence context-induced relapse or cue-induced reinstatement, but did suppress cocaine prime-induced reinstatement. These data indicate that the STEP-induced ERK dephosphorylation in the PrL cortex during early abstinence is a critical neuroadaptation that promotes relapse to cocaine seeking and that systemic versus intra-PrL cortical inhibition of STEP during early abstinence differentially suppresses cocaine seeking.

Age-related changes in STriatal-Enriched protein tyrosine Phosphatase levels: Regulation by BDNF

Recent results indicate that STriatal-Enriched protein tyrosine Phosphatase (STEP) levels are regulated by brain-derived neurotrophic factor (BDNF), whose expression changes during postnatal development and aging. Here, we studied STEP ontogeny in mouse brain and changes in STEP with age with emphasis on the possible regulation by BDNF. We found that STEP expression increased during the first weeks of life, reaching adult levels by 2-3weeks of age in the striatum and cortex, and by postnatal day (P) 7 in the hippocampus. STEP protein levels were unaffected in BDNF^+/- mice, but were significantly reduced in the striatum and cortex, but not in the hippocampus, of BDNF^-/- mice at P7 and P14. In adult wild-type mice there were no changes in cortical and hippocampal STEP₆₁ levels with age. Conversely, striatal STEP levels were reduced from 12months of age, correlating with higher ubiquitination and increased BDNF content and signaling. Lower STEP levels in older mice were paralleled by increased phosphorylation of its substrates. Since altered STEP levels are involved in cellular malfunctioning events, its reduction in the striatum with increasing age should encourage future studies of how this imbalance might participate in the aging process.

Striatal-enriched Tyrosine Protein Phosphatase (STEP) in the Mechanisms of Depressive Disorders

Striatal-enriched tyrosine protein phosphatase (STEP) is expressed mainly in the brain. Its dysregulation is associated with Alzheimer's and Huntington's diseases, schizophrenia, fragile X syndrome, drug abuse and stroke/ischemia. However, an association between STEP and depressive disorders is still obscure. The review discusses the theoretical foundations and experimental facts concerning possible relationship between STEP dysregulation and depression risk. STEP dephosphorylates and inactivates several key neuronal signaling proteins such as extracellular signal-regulating kinase 1 and 2 (ERK1/2), stress activated protein kinases p38, the Src family tyrosine kinases Fyn, Pyk2, NMDA and AMPA glutamate receptors. The inactivation of these proteins decreases the expression of brain derived neurotrophic factor (BDNF) necessary for neurogenesis and neuronal survival. The deficit of BDNF results in progressive degeneration of neurons in the hippocampus and cortex and increases depression risk. At the same time, a STEP inhibitor, 8-(trifluoromethyl)-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride (TC-2153), increases BDNF expression in the hippocampus and attenuated the depressivelike behavior in mice. Thus, STEP is involved in the mechanism of depressive disorders and it is a promising molecular target for atypical antidepressant drugs of new generation.

STEP inhibition reverses behavioral, electrophysiologic, and synaptic abnormalities in Fmr1 KO mice

Fragile X syndrome (FXS) is the leading cause of inherited intellectual disability, with additional symptoms including attention deficit and hyperactivity, anxiety, impulsivity, and repetitive movements or actions. The majority of FXS cases are attributed to a CGG expansion that leads to transcriptional silencing and diminished expression of fragile X mental retardation protein (FMRP). FMRP, an RNA binding protein, regulates the synthesis of dendritically-translated mRNAs by stalling ribosomal translation. Loss of FMRP leads to increased translation of some of these mRNAs, including the CNS-specific tyrosine phosphatase STEP (STriatal-Enriched protein tyrosine Phosphatase). Genetic reduction of STEP in Fmr1 KO mice have diminished audiogenic seizures and a reversal of social and non-social anxiety-related abnormalities. This study investigates whether a newly discovered STEP inhibitor (TC-2153) could attenuate the behavioral and synaptic abnormalities in Fmr1 KO mice. TC-2153 reversed audiogenic seizure incidences, reduced hyperactivity, normalized anxiety states, and increased sociability in Fmr1 KO mice. Moreover, TC-2153 reduced dendritic spine density and improved synaptic aberrations in Fmr1 KO neuronal cultures as well as in vivo. TC-2153 also reversed the mGluR-mediated exaggerated LTD in brain slices derived from Fmr1 KO mice. These studies suggest that STEP inhibition may have therapeutic benefit in FXS.

Alcohol-dependent molecular adaptations of the NMDA receptor system

Phenotypes such as motivation to consume alcohol, goal-directed alcohol seeking and habit formation take part in mechanisms underlying heavy alcohol use. Learning and memory processes greatly contribute to the establishment and maintenance of these behavioral phenotypes. The N-methyl-d-aspartate receptor (NMDAR) is a driving force of synaptic plasticity, a key cellular hallmark of learning and memory. Here, we describe data in rodents and humans linking signaling molecules that center around the NMDARs, and behaviors associated with the development and/or maintenance of alcohol use disorder (AUD). Specifically, we show that enzymes that participate in the regulation of NMDAR function including Fyn kinase as well as signaling cascades downstream of NMDAR including calcium/calmodulin-dependent protein kinase II (CamKII), the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) and the mammalian target of rapamycin complex 1 (mTORC1) play a major role in mechanisms underlying alcohol drinking behaviors. Finally, we emphasize the brain region specificity of alcohol's actions on the above-mentioned signaling pathways and attempt to bridge the gap between the molecular signaling that drive learning and memory processes and alcohol-dependent behavioral phenotypes. Finally, we present data to suggest that genes related to NMDAR signaling may be AUD risk factors.

STEP File Analyzer Software

The STEP File Analyzer is a software tool that generates a spreadsheet or a set of CSV (comma-separated value) files from a STEP (ISO 10303 –STandard for Exchange of Product model data) Part 21 file. STEP files are used to represent product and manufacturing information (PMI) and for data exchange and interoperability between Computer-Aided Design (CAD), Manufacturing (CAM), Analysis (CAE), and Inspection (CMM) software related to the smart manufacturing digital thread. STEP is also used for the long-term archiving and retrieval of product data. A spreadsheet simplifies inspecting information from the STEP file at an entity and attribute level. Typical STEP file viewers show a 3D visualization of the part or model represented by the STEP file. The viewers usually have a high-level hierarchical display of the information in the STEP file where the user can drill down to individual attributes of parts. However, there is no way to view all of the actual STEP entities and their attributes at once. The STEP File Analyzer provides this capability by creating a spreadsheet from the STEP file. The STEP File Analyzer also generates reports for PMI Representation, PMI Presentation, and Validation Properties based on Recommended Practices defined by the CAx Implementor Forum (CAx-IF) [5]. The objective of the CAx-IF is to advance CAx (mainly Computer-Aided Design and Engineering) software system STEP translator development and to ensure that user requirements for interoperability are satisfied.

Solar-driven thermo- and electrochemical degradation of nitrobenzene in wastewater: Adaptation and adoption of solar STEP concept

The STEP concept has successfully been demonstrated for driving chemical reaction by utilization of solar heat and electricity to minimize the fossil energy, meanwhile, maximize the rate of thermo- and electrochemical reactions in thermodynamics and kinetics. This pioneering investigation experimentally exhibit that the STEP concept is adapted and adopted efficiently for degradation of nitrobenzene. By employing the theoretical calculation and thermo-dependent cyclic voltammetry, the degradation potential of nitrobenzene was found to be decreased obviously, at the same time, with greatly lifting the current, while the temperature was increased. Compared with the conventional electrochemical methods, high efficiency and fast degradation rate were markedly displayed due to the co-action of thermo- and electrochemical effects and the switch of the indirect electrochemical oxidation to the direct one for oxidation of nitrobenzene. A clear conclusion on the mechanism of nitrobenzene degradation by the STEP can be schematically proposed and discussed by the combination of thermo- and electrochemistry based the analysis of the HPLC, UV-vis and degradation data. This theory and experiment provide a pilot for the treatment of nitrobenzene wastewater with high efficiency, clean operation and low carbon footprint, without any other input of energy and chemicals from solar energy.

Brain Network Activation Analysis Utilizing Spatiotemporal Features for Event Related Potentials Classification

The purpose of this study was to introduce an improved tool for automated classification of event-related potentials (ERPs) using spatiotemporally parcellated events incorporated into a functional brain network activation (BNA) analysis. The auditory oddball ERP paradigm was selected to demonstrate and evaluate the improved tool. Methods: The ERPs of each subject were decomposed into major dynamic spatiotemporal events. Then, a set of spatiotemporal events representing the group was generated by aligning and clustering the spatiotemporal events of all individual subjects. The temporal relationship between the common group events generated a network, which is the spatiotemporal reference BNA model. Scores were derived by comparing each subject's spatiotemporal events to the reference BNA model and were then entered into a support vector machine classifier to classify subjects into relevant subgroups. The reliability of the BNA scores (test-retest repeatability using intraclass correlation) and their utility as a classification tool were examined in the context of Target-Novel classification. Results: BNA intraclass correlation values of repeatability ranged between 0.51 and 0.82 for the known ERP components N100, P200, and P300. Classification accuracy was high when the trained data were validated on the same subjects for different visits (AUCs 0.93 and 0.95). The classification accuracy remained high for a test group recorded at a different clinical center with a different recording system (AUCs 0.81, 0.85 for 2 visits). Conclusion: The improved spatiotemporal BNA analysis demonstrates high classification accuracy. The BNA analysis method holds promise as a tool for diagnosis, follow-up and drug development associated with different neurological conditions.

Improved enteral tolerance following step procedure: systematic literature review and meta-analysis

Surgical management of children with short bowel syndrome (SBS) changed with the introduction of the serial transverse enteroplasty procedure (STEP). We conducted a systematic review and meta-analysis using MEDLINE and SCOPUS to determine if children with SBS had improved enteral tolerance following STEP. Studies were included if information about a child's pre- and post-STEP enteral tolerance was provided. A random effects meta-analysis provided a summary estimate of the proportion of children with enteral tolerance increase following STEP. From 766 abstracts, seven case series involving 86 children were included. Mean percent tolerance of enteral nutrition improved from 35.1 to 69.5. Sixteen children had no enteral improvement following STEP. A summary estimate showed that 87 % (95 % CI 77-95 %) of children who underwent STEP had an increase in enteral tolerance. Compilation of the literature supports the belief that SBS subjects' enteral tolerance improves following STEP. Enteral nutritional tolerance is a measure of efficacy of STEP and should be presented as a primary or secondary outcome. By standardizing data collection on children undergoing STEP procedure, better determination of nutritional benefit from STEP can be ascertained.

PSD-95 stabilizes NMDA receptors by inducing the degradation of STEP61

Phosphorylation regulates surface and synaptic expression of NMDA receptors (NMDARs). Both the tyrosine kinase Fyn and the tyrosine phosphatase striatal-enriched protein tyrosine phosphatase (STEP) are known to target the NMDA receptor subunit GluN2B on tyrosine 1472, which is a critical residue that mediates NMDAR endocytosis. STEP reduces the surface expression of NMDARs by promoting dephosphorylation of GluN2B Y1472, whereas the synaptic scaffolding protein postsynaptic density protein 95 (PSD-95) stabilizes the surface expression of NMDARs. However, nothing is known about a potential functional interaction between STEP and PSD-95. We now report that STEP61 binds to PSD-95 but not to other PSD-95 family members. We find that PSD-95 expression destabilizes STEP61 via ubiquitination and degradation by the proteasome. Using subcellular fractionation, we detect low amounts of STEP61 in the PSD fraction. However, STEP61 expression in the PSD is increased upon knockdown of PSD-95 or in vivo as detected in PSD-95-KO mice, demonstrating that PSD-95 excludes STEP61 from the PSD. Importantly, only extrasynaptic NMDAR expression and currents were increased upon STEP knockdown, as is consistent with low STEP61 localization in the PSD. Our findings support a dual role for PSD-95 in stabilizing synaptic NMDARs by binding directly to GluN2B but also by promoting synaptic exclusion and degradation of the negative regulator STEP61.

A new trial design to accelerate tuberculosis drug development: the Phase IIC Selection Trial with Extended Post-treatment follow-up (STEP)

BACKGROUND

The standard 6-month four-drug regimen for the treatment of drug-sensitive tuberculosis has remained unchanged for decades and is inadequate to control the epidemic. Shorter, simpler regimens are urgently needed to defeat what is now the world's greatest infectious disease killer.

METHODS

We describe the Phase IIC Selection Trial with Extended Post-treatment follow-up (STEP) as a novel hybrid phase II/III trial design to accelerate regimen development. In the Phase IIC STEP trial, the experimental regimen is given for the duration for which it will be studied in phase III (presently 3 or 4 months) and patients are followed for clinical outcomes of treatment failure and relapse for a total of 12 months from randomisation. Operating characteristics of the trial design are explored assuming a classical frequentist framework as well as a Bayesian framework with flat and sceptical priors. A simulation study is conducted using data from the RIFAQUIN phase III trial to illustrate how such a design could be used in practice.

RESULTS

With 80 patients per arm, and two (2.5 %) unfavourable outcomes in the STEP trial, there is a probability of 0.99 that the proportion of unfavourable outcomes in a potential phase III trial would be less than 12 % and a probability of 0.91 that the proportion of unfavourable outcomes would be less than 8 %. With six (7.5 %) unfavourable outcomes, there is a probability of 0.82 that the proportion of unfavourable outcomes in a potential phase III trial would be less than 12 % and a probability of 0.41 that it would be less than 8 %. Simulations using data from the RIFAQUIN trial show that a STEP trial with 80 patients per arm would have correctly shown that the Inferior Regimen should not proceed to phase III and would have had a high chance (0.88) of either showing that the Successful Regimen could proceed to phase III or that it might require further optimisation.

CONCLUSIONS

Collection of definitive clinical outcome data in a relatively small number of participants over only 12 months provides valuable information about the likelihood of success in a future phase III trial. We strongly believe that the STEP trial design described herein is an important tool that would allow for more informed decision-making and accelerate regimen development.

Aging is associated with dimerization and inactivation of the brain-enriched tyrosine phosphatase STEP

The STriatal-Enriched tyrosine Phosphatase (STEP) is involved in the etiology of several age-associated neurologic disorders linked to oxidative stress and is also known to play a role in neuroprotection by modulating glutamatergic transmission. However, the possible effect of aging on STEP level and activity in the brain is still unclear. In this study, using young (1 month), adult (4 months), and aged (18 months) rats, we show that aging is associated with increase in dimerization and loss of activity of STEP. Increased dimerization of STEP is primarily observed in the cortex and hippocampus and is associated with depletion of both reduced and total glutathione levels, suggesting an increase in oxidative stress. Consistent with this interpretation, studies in cell culture models of glutathione depletion and oxidative stress also demonstrate formation of dimers and higher order oligomers of STEP that involve intermolecular disulfide bond formation between multiple cysteine residues. Conversely, administration of N-acetyl cysteine, a major antioxidant that enhances glutathione biosynthesis, attenuates STEP dimerization both in the cortex and hippocampus. The findings indicate that loss of this intrinsic protective response pathway with age-dependent increase in oxidative stress may be a contributing factor for the susceptibility of the brain to age-associated neurologic disorders.

Zn2+-dependent Activation of the Trk Signaling Pathway Induces Phosphorylation of the Brain-enriched Tyrosine Phosphatase STEP: MOLECULAR BASIS FOR ZN2+-INDUCED ERK MAPK ACTIVATION

Excessive release of Zn(2+) in the brain is implicated in the progression of acute brain injuries. Although several signaling cascades have been reported to be involved in Zn(2+)-induced neurotoxicity, a potential contribution of tyrosine phosphatases in this process has not been well explored. Here we show that exposure to high concentrations of Zn(2+) led to a progressive increase in phosphorylation of the striatal-enriched phosphatase (STEP), a component of the excitotoxic-signaling pathway that plays a role in neuroprotection. Zn(2+)-mediated phosphorylation of STEP61 at multiple sites (hyperphosphorylation) was induced by the up-regulation of brain-derived neurotropic factor (BDNF), tropomyosin receptor kinase (Trk) signaling, and activation of cAMP-dependent PKA (protein kinase A). Mutational studies further show that differential phosphorylation of STEP61 at the PKA sites, Ser-160 and Ser-221 regulates the affinity of STEP61 toward its substrates. Consistent with these findings we also show that BDNF/Trk/PKA mediated signaling is required for Zn(2+)-induced phosphorylation of extracellular regulated kinase 2 (ERK2), a substrate of STEP that is involved in Zn(2+)-dependent neurotoxicity. The strong correlation between the temporal profile of STEP61 hyperphosphorylation and ERK2 phosphorylation indicates that loss of function of STEP61 through phosphorylation is necessary for maintaining sustained ERK2 phosphorylation. This interpretation is further supported by the findings that deletion of the STEP gene led to a rapid and sustained increase in ERK2 phosphorylation within minutes of exposure to Zn(2+). The study provides further insight into the mechanisms of regulation of STEP61 and also offers a molecular basis for the Zn(2+)-induced sustained activation of ERK2.

Down-regulation of BDNF in cell and animal models increases striatal-enriched protein tyrosine phosphatase 61 (STEP61 ) levels

Brain-derived neurotrophic factor (BDNF) regulates synaptic strengthening and memory consolidation, and altered BDNF expression is implicated in a number of neuropsychiatric and neurodegenerative disorders. BDNF potentiates N-methyl-D-aspartate receptor function through activation of Fyn and ERK1/2. STriatal-Enriched protein tyrosine Phosphatase (STEP) is also implicated in many of the same disorders as BDNF but, in contrast to BDNF, STEP opposes the development of synaptic strengthening. STEP-mediated dephosphorylation of the NMDA receptor subunit GluN2B promotes internalization of GluN2B-containing NMDA receptors, while dephosphorylation of the kinases Fyn, Pyk2, and ERK1/2 leads to their inactivation. Thus, STEP and BDNF have opposing functions. In this study, we demonstrate that manipulation of BDNF expression has a reciprocal effect on STEP61 levels. Reduced BDNF signaling leads to elevation of STEP61 both in BDNF(+/-) mice and after acute BDNF knockdown in cortical cultures. Moreover, a newly identified STEP inhibitor reverses the biochemical and motor abnormalities in BDNF(+/-) mice. In contrast, increased BDNF signaling upon treatment with a tropomyosin receptor kinase B agonist results in degradation of STEP61 and a subsequent increase in the tyrosine phosphorylation of STEP substrates in cultured neurons and in mouse frontal cortex. These findings indicate that BDNF-tropomyosin receptor kinase B signaling leads to degradation of STEP61 , while decreased BDNF expression results in increased STEP61 activity. A better understanding of the opposing interaction between STEP and BDNF in normal cognitive functions and in neuropsychiatric disorders will hopefully lead to better therapeutic strategies. Altered expression of BDNF and STEP61 has been implicated in several neurological disorders. BDNF and STEP61 are known to regulate synaptic strengthening, but in opposite directions. Here, we report that reduced BDNF signaling leads to elevation of STEP61 both in BDNF(+/-) mice and after acute BDNF knockdown in cortical cultures. In contrast, activation of TrkB receptor results in the degradation of STEP61 and reverses hyperlocomotor activity in BDNF(+/-) mice. Moreover, inhibition of STEP61 by TC-2153 is sufficient to enhance the Tyr phosphorylation of STEP substrates and also reverses hyperlocomotion in BDNF(+/-) mice. These findings give us a better understanding of the regulation of STEP61 by BDNF in normal cognitive functions and in neuropsychiatric disorders.

The Surgical Approach to Short Bowel Syndrome - Autologous Reconstruction versus Transplantation

BACKGROUND

Short bowel syndrome (SBS) is a state of malabsorption resulting from massive small bowel resection leading to parenteral nutrition (PN) dependency. Considerable advances have been achieved in the medical and surgical management of SBS over the last few decades.

METHODS

This review discusses in detail the surgical approach to SBS.

RESULTS

Widespread use of PN enables long-term survival in patients with intestinal failure but at the cost of PN-associated life-threatening complications including catheter-associated blood stream infection, venous thrombosis, and liver disease. The goal of management of intestinal failure due to SBS is to enable enteral autonomy and wean PN by means of a multi-disciplinary approach. Availability of modified enteral feeding formulas have simplified nutrition supplementation in SBS patients. Similarly, advances in the medical field have made medications like growth hormone and glucagon-like peptide (GLP2) available to improve water and nutrient absorption as well as to enable achieving enteral autonomy. Autologous gastrointestinal reconstruction (AGIR) includes various techniques which manipulate the bowel surgically to facilitate the bowel adaptation process and restoration of enteral nutrition. Ultimately, intestinal transplantation can serve as the last option for the cure of intestinal failure when selectively applied.

CONCLUSION

SBS continues to be a challenging medical problem. Best patient outcomes can be achieved through an individualized plan, using various AGIR techniques to complement each other, and intestinal transplantation as a last resort for cure. Maximum benefit and improved outcomes can be achieved by caring for SBS patients at highly specialized intestinal rehabilitation centers.

A single fraction from Uncaria sinensis exerts neuroprotective effects against glutamate-induced neurotoxicity in primary cultured cortical neurons

We identified a neuroprotective single fraction among 62 ones of hexane extract from Uncaria sinensis (JGH43IA) and investigated its effects and mechanisms in primary cortical neurons. Pretreatment with JGH43IA showed a significantly increase cell viability in a dose-dependent manner with a decrease in the lactate dehydrogenase release. When we performed morphological assay and flow cytometry to determination of the type of cell death, pretreatment with JGH43IA showed a significant reduction of glutamate-induced apoptotic cell death. Then we explored the downstream signaling pathways of N-methyl-D-aspartate receptor (NMDAR) with calpain activation to elucidate possible pathways of neuroprotection by JGH43IA. Pretreatment with JGH43IA exhibited a significant attenuation of NMDAR GluN2B subunit activation and a decrease in active form of calpain 1 leading to subsequent cleavage of striatal-enriched protein tyrosine phosphatase (STEP). In addition, pretreatment with JGH43IA showed a marked increase of cAMP responsive element binding protein. These results suggest that JGH43IA may have neuroprotective effects through down-regulation of NMDAR GluN2B subunit and calpain 1 activation, and subsequent alleviation of STEP cleavage. This single fraction from U. sinensis might be a useful therapeutic agent for brain disorder associated with glutamate injury.

Protein expression of targets of the FMRP regulon is altered in brains of subjects with schizophrenia and mood disorders

Fragile X mental retardation protein (FMRP) is an RNA binding protein with 842 target mRNAs in mammalian brain. Silencing of the fragile X mental retardation 1 (FMR1) gene leads to loss of expression of FMRP and upregulated metabotropic glutamate receptor 5 (mGluR5) signaling resulting in the multiple physical and cognitive deficits associated with fragile X syndrome (FXS). Reduced FMRP expression has been identified in subjects with autism, schizophrenia, bipolar disorder, and major depression who do not carry the mutation for FMR1. Our laboratory has recently demonstrated altered expression of four downstream targets of FMRP-mGluR5 signaling in brains of subjects with autism: homer 1, amyloid beta A4 precursor protein (APP), ras-related C3 botulinum toxin substrate 1 (RAC1), and striatal-enriched protein tyrosine phosphatase (STEP). In the current study we investigated the expression of the same four proteins in lateral cerebella of subjects with schizophrenia, bipolar disorder, and major depression and in frontal cortex of subjects with schizophrenia and bipolar disorder. In frontal cortex we observed: 1) reduced expression of 120 kDa form of APP in subjects with schizophrenia and bipolar disorder; 2) reduced expression of 61 kDa and 33k Da forms of STEP in subjects with schizophrenia; 3) reduced expression of 88 kDa form of APP in subjects with bipolar disorder; and 3) trends for reduced expression of 88 kDa form of APP and homer 1 in subjects with schizophrenia and bipolar disorder, respectively. In lateral cerebella there was no group difference, however we observed increased expression of RAC1 in subjects with bipolar disorder, and trends for increased RAC1 in subjects with schizophrenia and major depression. Our results provide further evidence that proteins involved in the FMRP-mGluR5 signaling pathway are altered in schizophrenia and mood disorders.

Striatal-enriched protein tyrosine phosphatase regulates the PTPα/Fyn signaling pathway

The tyrosine kinase Fyn has two regulatory tyrosine residues that when phosphorylated either activate (Tyr(420)) or inhibit (Tyr(531)) Fyn activity. Within the central nervous system, two protein tyrosine phosphatases (PTPs) target these regulatory tyrosines in Fyn. PTPα dephosphorylates Tyr(531) and activates Fyn, while STEP (STriatal-Enriched protein tyrosine Phosphatase) dephosphorylates Tyr(420) and inactivates Fyn. Thus, PTPα and STEP have opposing functions in the regulation of Fyn; however, whether there is cross talk between these two PTPs remains unclear. Here, we used molecular techniques in primary neuronal cultures and in vivo to demonstrate that STEP negatively regulates PTPα by directly dephosphorylating PTPα at its regulatory Tyr(789). Dephosphorylation of Tyr(789) prevents the translocation of PTPα to synaptic membranes, blocking its ability to interact with and activate Fyn. Genetic or pharmacologic reduction in STEP61 activity increased the phosphorylation of PTPα at Tyr(789), as well as increased translocation of PTPα to synaptic membranes. Activation of PTPα and Fyn and trafficking of GluN2B to synaptic membranes are necessary for ethanol (EtOH) intake behaviors in rodents. We tested the functional significance of STEP61 in this signaling pathway by EtOH administration to primary cultures as well as in vivo, and demonstrated that the inactivation of STEP61 by EtOH leads to the activation of PTPα, its translocation to synaptic membranes, and the activation of Fyn. These findings indicate a novel mechanism by which STEP61 regulates PTPα and suggest that STEP and PTPα coordinate the regulation of Fyn. STEP61 , PTPα, Fyn, and NMDA receptor (NMDAR) have been implicated in ethanol intake behaviors in the dorsomedial striatum (DMS) in rodents. Here, we report that PTPα is a novel substrate for STEP61. Upon ethanol exposure, STEP61 is phosphorylated and inactivated by protein kinase A (PKA) signaling in the DMS. As a result of STEP61 inhibition, there is an increase in the phosphorylation of PTPα, which translocates to lipid rafts and activates Fyn and subsequent NMDAR signaling. The results demonstrate a synergistic regulation of Fyn-NMDAR signaling by STEP61 and PTPα, which may contribute to the regulation of ethanol-related behaviors. NMDA, N-methyl-D-aspartate; PTPα, receptor-type protein tyrosine phosphatase alpha; STEP, STriatal-Enriched protein tyrosine Phosphatase.

Synthesis of benzopentathiepin analogs and their evaluation as inhibitors of the phosphatase STEP

Striatal-enriched protein tyrosine phosphatase (STEP) is a brain specific protein tyrosine phosphatase that has been implicated in many neurodegenerative diseases, such as Alzheimer's disease. We recently reported the benzopentathiepin TC-2153 as a potent inhibitor of STEP in vitro, cells and animals. Herein, we report the synthesis and evaluation of TC-2153 analogs in order to define what structural features are important for inhibition and to identify positions tolerant of substitution for further study. The trifluoromethyl substitution is beneficial for inhibitor potency, and the amine is tolerant of acylation, and thus provides a convenient handle for introducing additional functionality such as reporter groups.

STEP61 is a substrate of the E3 ligase parkin and is upregulated in Parkinson's disease

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc). The loss of SNc dopaminergic neurons affects the plasticity of striatal neurons and leads to significant motor and cognitive disabilities during the progression of the disease. PARK2 encodes for the E3 ubiquitin ligase parkin and is implicated in genetic and sporadic PD. Mutations in PARK2 are a major contributing factor in the early onset of autosomal-recessive juvenile parkinsonism (AR-JP), although the mechanisms by which a disruption in parkin function contributes to the pathophysiology of PD remain unclear. Here we demonstrate that parkin is an E3 ligase for STEP61 (striatal-enriched protein tyrosine phosphatase), a protein tyrosine phosphatase implicated in several neuropsychiatric disorders. In cellular models, parkin ubiquitinates STEP61 and thereby regulates its level through the proteasome system, whereas clinically relevant parkin mutants fail to do so. STEP61 protein levels are elevated on acute down-regulation of parkin or in PARK2 KO rat striatum. Relevant to PD, STEP61 accumulates in the striatum of human sporadic PD and in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mice. The increase in STEP61 is associated with a decrease in the phosphorylation of its substrate ERK1/2 and the downstream target of ERK1/2, pCREB [phospho-CREB (cAMP response element-binding protein)]. These results indicate that STEP61 is a novel substrate of parkin, although further studies are necessary to determine whether elevated STEP61 levels directly contribute to the pathophysiology of PD.

Short bowel syndrome in children: surgical and medical perspectives

The main cause of intestinal failure in children is due to short bowel syndrome (SBS) resulting from congenital or acquired intestinal lesions. From the first lengthening procedure introduced by Bianchi, the last three decades have seen lengthening procedures established as fundamental components of multidisciplinary intestinal rehabilitation programs. Debate on indications and timing of the procedures is still open leaving SBS surgical treatment a great challenge. However, enteral autonomy is possible only with an individualized approach remembering that each SBS patient is unique. Current literature on autologous gastrointestinal reconstruction technique was reviewed aiming to assess a comprehensive pathway in SBS non-transplant management.

Disruption of striatal-enriched protein tyrosine phosphatase (STEP) function in neuropsychiatric disorders

Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific tyrosine phosphatase that plays a major role in the development of synaptic plasticity. Recent findings have implicated STEP in several psychiatric and neurological disorders, including Alzheimer's disease, schizophrenia, fragile X syndrome, Huntington's disease, stroke/ischemia, and stress-related psychiatric disorders. In these disorders, STEP protein expression levels and activity are dysregulated, contributing to the cognitive deficits that are present. In this review, we focus on the most recent findings on STEP, discuss how STEP expression and activity are maintained during normal cognitive function, and how disruptions in STEP activity contribute to a number of illnesses.

Behavioral characterization of striatal-enriched protein tyrosine phosphatase (STEP) knockout mice

Striatal-enriched protein tyrosine phosphatase (STEP) has been described as a regulator of multiple kinases and glutamate receptor subunits critical for synaptic plasticity. Published behavioral and biochemical characterization from the founder line of STEP knockout (KO) mice revealed superior cognitive performance, with enhanced phosphorylation of substrates such as ERK, Fyn and GluN2B; suggesting that inhibitors of STEP may have potential as therapeutic agents for the treatment of neuropsychiatric disorders. The objectives of this work aimed to replicate and extend the previously reported behavioral consequences of STEP knockout. Consistent with previous reported data, STEP KO mice demonstrated exploratory activity levels and similar motor coordination relative to WT littermate controls as well as intact memory in a Y-maze spatial novelty test. Interestingly, KO mice demonstrated deficits in pre-pulse inhibition as well as reduced seizure threshold relative to WT controls. Immunohistochemical staining of brains revealed the expected gene-dependent reduction in STEP protein confirming knockout in the mice. The present data confirm expression and localization of STEP and the absence in KO mice, and describe functional downstream implications of reducing STEP levels in vivo.

A proficiency-based skills training curriculum for the SAGES surgical training for endoscopic proficiency (STEP) program

INTRODUCTION

The surgical training for endoscopic proficiency program is a collaborative project between Society of American Gastrointestinal and Endoscopic Surgeons and Olympus America Inc. dedicated to providing flexible endoscopy training to surgery residency programs. Currently it lacks models for proficiency-based training. This study developed 2 novel flexible endoscopy simulators, purchased a third, and established face and content validity as well as proficiency metrics for all 3.

METHODS

Three simulators were tested-a foam and cardboard upper gastrointestinal tract model, a commercially available colonoscopy model (CM-15, Olympus, Japan), and an endoscopic targeting model created from the Operation Game (Hasbro). Time and errors for the performance of 12 expert surgical endoscopists on each model were used to calculate proficiency scores. Face validity and content validity were established through posttest questionnaires using a 5-point Likert scale.

RESULTS

Experts had a mean of 8 years of endoscopic practice (range: 1-24y). Among them, 83% teach residents or fellows using simulation. Most perform more than 50 upper endoscopies (51 to >500) and 100 colonoscopies (101 to >500) per year. The average time for completing the upper gastrointestinal tract model with correct identification of all targets was 133 ± 56 seconds. Complete navigation of the colonoscopy model averaged 325 ± 156 seconds. Proper orientation and targeting using the Operation Game model averaged 273 ± 109 seconds with 3 errors.

CONCLUSIONS

This study proves face and content validity for 3 physical flexible endoscopy simulators that can be used to train upper and lower endoscopy as well as instrument targeting. It also establishes expert proficiency metrics that can be used by trainees for structured rehearsal. These relatively inexpensive models will be incorporated into the surgical training for endoscopic proficiency curriculum.

Serial transverse enteroplasty allows children with short bowel to wean from parenteral nutrition

OBJECTIVE

To analyze the effects of serial transverse enteroplasty (STEP) on parenteral and enteral calories in children with short bowel syndrome, and examine short- and long-term complications.

STUDY DESIGN

A retrospective analysis of prospectively-collected data from a large single center cohort of patients undergoing STEP procedure was analyzed. Baseline demographic and clinical information, operative data, and short- and long-term complications were recorded. Detailed growth and nutritional data were obtained for 6 months prior and 12 months following STEP procedure.

RESULTS

Sixty-eight procedures were performed in 51 patients over a 68-month period. Median bowel length at first STEP was 51 cm with a median length gain of 54%. Repeat STEP patients had longer initial length (77 cm) and reduced length gain (20%). Operative times and blood loss were low, with few complications. Parenteral calorie requirement was stable or rising for 6 months prior to STEP, but decreased to median <20 kCal/kg/d at 1 year postop. Longer length gains were associated with higher risk of stricture formation. Seven children were transplanted, and 60% of nontransplanted children were enterally independent, with the remainder making ongoing progress; 48/51 children are alive at a median of 39 months follow-up.

CONCLUSIONS

STEP is shown to be safe, well tolerated, and to have definitive benefit in reducing parenteral calorie requirements over the first year following the procedure. It has an important role in achieving enteral independence in children with short bowel syndrome.

Striatal-enriched protein tyrosine phosphatase-STEPs toward understanding chronic stress-induced activation of corticotrophin releasing factor neurons in the rat bed nucleus of the stria terminalis

BACKGROUND

Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific protein tyrosine phosphatase that opposes the development of synaptic strengthening and the consolidation of fear memories. In contrast, stress facilitates fear memory formation, potentially by activating corticotrophin releasing factor (CRF) neurons in the anterolateral cell group of the bed nucleus of the stria terminalis (BNSTALG).

METHODS

Here, using dual-immunofluorescence, single-cell reverse transcriptase polymerase chain reaction, quantitative reverse transcriptase polymerase chain reaction, Western blot, and whole-cell patch-clamp electrophysiology, we examined the expression and role of STEP in regulating synaptic plasticity in rat BNSTALG neurons and its modulation by stress.

RESULTS

Striatal-enriched protein tyrosine phosphatase was selectively expressed in CRF neurons in the oval nucleus of the BNSTALG. Following repeated restraint stress (RRS), animals displayed a significant increase in anxiety-like behavior, which was associated with a downregulation of STEP messenger RNA and protein expression in the BNSTALG, as well as selectively enhancing the magnitude of long-term potentiation (LTP) induced in Type III, putative CRF neurons. To determine if the changes in STEP expression following RRS were mechanistically related to LTP facilitation, we examined the effects of intracellular application of STEP on the induction of LTP. STEP completely blocked the RRS-induced facilitation of LTP in BNSTALG neurons.

CONCLUSIONS

Hence, STEP acts to buffer CRF neurons against excessive activation, while downregulation of STEP after chronic stress may result in pathologic activation of CRF neurons in the BNSTALG and contribute to prolonged states of anxiety. Thus, targeted manipulations of STEP activity might represent a novel treatment strategy for stress-induced anxiety disorders.

Successful rehabilitation in pediatric ultrashort small bowel syndrome

OBJECTIVE

To examine treatment outcomes in pediatric patients with ultrashort small bowel (USSB) syndrome in an intestinal rehabilitation program (IRP).

STUDY DESIGN

We reviewed IRP records for 2001-2011 and identified 28 children with USSB (≤ 20 cm of small bowel). We performed univariate analysis using the Fisher exact test and Wilcoxon rank-sum test to compare characteristics of children who achieved parenteral nutrition (PN) independence with intact native bowel and those who did not. Growth, nutritional status, and hepatic laboratory test results were compared from the time of enrollment to the most recent values using the Wilcoxon signed-rank test.

RESULTS

Of the 28 patients identified, 27 (96%) survived. Almost one-half (48%) of these survivors achieved PN independence with their native bowel. The successfully rehabilitated patients were more likely to have an intact colon and ileocecal valve (P = .01). Significant improvements in PN kcal/kg, total bilirubin, and height and weight z-scores were seen in all patients, but serum hepatic transaminase levels did not improve in the nonrehabilitated patients.

CONCLUSION

Enrollment in an IRP provides an excellent probability of survival for children with USSB. The presence of an intact ileocecal valve and colon are positively associated with rehabilitation in this population, but are not requisite. Approximately one-half of patients with USSB can achieve rehabilitation, with a median time to PN independence of less than 2 years. The USSB population can attain reduced PN dependence, improvement of PN-associated liver disease, and enhanced growth with the aid of an IRP.