Robert Kozol

Two knockdown models of the autism genes SYNGAP1 and SHANK3 in zebrafish produce similar behavioral phenotypes associated with embryonic disruptions of brain morphogenesis

Despite significant progress in the genetics of autism spectrum disorder (ASD), how genetic mutations translate to the behavioral changes characteristic of ASD remains largely unknown. ASD affects 1-2% of children and adults, and is characterized by deficits in verbal and non-verbal communication, and social interactions, as well as the presence of repetitive behaviors and/or stereotyped interests. ASD is clinically and etiologically heterogeneous, with a strong genetic component. Here, we present functional data from syngap1 and shank3 zebrafish loss-of-function models of ASD. SYNGAP1, a synaptic Ras GTPase activating protein, and SHANK3, a synaptic scaffolding protein, were chosen because of mounting evidence that haploinsufficiency in these genes is highly penetrant for ASD and intellectual disability (ID). Orthologs of both SYNGAP1 and SHANK3 are duplicated in the zebrafish genome and we find that all four transcripts (syngap1a, syngap1b, shank3a and shank3b) are expressed at the earliest stages of nervous system development with pronounced expression in the larval brain. Consistent with early expression of these genes, knockdown of syngap1b or shank3a cause common embryonic phenotypes including delayed mid- and hindbrain development, disruptions in motor behaviors that manifest as unproductive swim attempts, and spontaneous, seizure-like behaviors. Our findings indicate that both syngap1b and shank3a play novel roles in morphogenesis resulting in common brain and behavioral phenotypes.

Distinct phenotypes in zebrafish models of human startle disease.

Startle disease is an inherited neurological disorder that causes affected individuals to suffer noise- or touch-induced non-epileptic seizures, excessive muscle stiffness and neonatal apnea episodes. Mutations known to cause startle disease have been identified in glycine receptor subunit (GLRA1 and GLRB) and glycine transporter (SLC6A5) genes, which serve essential functions at glycinergic synapses. Despite the significant successes in identifying startle disease mutations, many idiopathic cases remain unresolved. Exome sequencing in these individuals will identify new candidate genes. To validate these candidate disease genes, zebrafish is an ideal choice due to rapid knockdown strategies, accessible embryonic stages, and stereotyped behaviors. The only existing zebrafish model of startle disease, bandoneon (beo), harbors point mutations in glrbb (one of two zebrafish orthologs of human GLRB) that cause compromised glycinergic transmission and touch-induced bilateral muscle contractions. In order to further develop zebrafish as a model for startle disease, we sought to identify common phenotypic outcomes of knocking down zebrafish orthologs of two known startle disease genes, GLRA1 and GLRB, using splice site-targeted morpholinos. Although both morphants were expected to result in phenotypes similar to the zebrafish beo mutant, our direct comparison demonstrated that while both glra1 and glrbb morphants exhibited embryonic spasticity, only glrbb morphants exhibited bilateral contractions characteristic of beo mutants. Likewise, zebrafish over-expressing a dominant startle disease mutation (GlyR α1R271Q) exhibited spasticity but not bilateral contractions. Since GlyR βb can interact with GlyR α subunits 2–4 in addition to GlyR α1, loss of the GlyR βb subunit may produce more severe phenotypes by affecting multiple GlyR subtypes. Indeed, immunohistochemistry of glra1 morphants suggests that in zebrafish, alternate GlyR α subunits can compensate for the loss of the GlyR α1 subunit. To address the potential for interplay among GlyR subunits during development, we quantified the expression time-course for genes known to be critical to glycinergic synapse function. We found that GlyR α2, α3 and α4a are expressed in the correct temporal pattern and could compensate for the loss of the GlyR α1 subunit. Based on our findings, future studies that aim to model candidate startle disease genes in zebrafish should include measures of spasticity and synaptic development.

Function Over Form: Modeling Groups of Inherited Neurological Conditions in Zebrafish

Zebrafish are a unique cell to behavior model for studying the basic biology of human inherited neurological conditions. Conserved vertebrate genetics and optical transparency provide in vivo access to the developing nervous system as well as high-throughput approaches for drug screens. Here we review zebrafish modeling for two broad groups of inherited conditions that each share genetic and molecular pathways and overlap phenotypically: neurodevelopmental disorders such as Autism Spectrum Disorders (ASD), Intellectual Disability (ID) and Schizophrenia (SCZ), and neurodegenerative diseases, such as Cerebellar Ataxia (CATX), Hereditary Spastic Paraplegia (HSP) and Charcot-Marie Tooth Disease (CMT). We also conduct a small meta-analysis of zebrafish orthologs of high confidence neurodevelopmental disorder and neurodegenerative disease genes by looking at duplication rates and relative protein sizes. In the past zebrafish genetic models of these neurodevelopmental disorders and neurodegenerative diseases have provided insight into cellular, circuit and behavioral level mechanisms contributing to these conditions. Moving forward, advances in genetic manipulation, live imaging of neuronal activity and automated high-throughput molecular screening promise to help delineate the mechanistic relationships between different types of neurological conditions and accelerate discovery of therapeutic strategies.

Grynfeltt Hernia: A Deceptive Lumbar Mass with a Lipoma-Like Presentation

The Grynfeltt-Lesshaft hernia is a rare posterior abdominal wall defect that allows for the herniation of retro- and intraperitoneal structures through the upper lumbar triangle. While this hernia may initially present as a small asymptomatic bulge, the defect typically enlarges over time and can become symptomatic with potentially serious complications. In order to avoid that outcome, it is advisable to electively repair Grynfeltt hernias in patients without significant contraindications to surgery. Due to the limited number of lumbar hernioplasties performed, there has not been a large study that definitively identifies the best repair technique. It is generally accepted that abdominal hernias such as these should be repaired by tension-free methods. Both laparoscopic and open techniques are described in modern literature with unique advantages and complications for each. We present the case of an unexpected Grynfeltt hernia diagnosed following an attempted lipoma resection. We chose to perform an open repair involving a combination of fascial approximation and dual-layer polypropylene mesh placement. The patients recovery was uneventful and there has been no evidence of recurrence at over six months. Our goal herein is to increase awareness of upper lumbar hernias and to discuss approaches to their surgical management.

Foreign Bodies and Bezoars of the Stomach and Small Intestine

Abstract Foreign bodies, including bezoars of the stomach and small bowel, are a fairly common problem encountered by gastroenterologists and surgeons. Most resolve without intervention; however, it is important for surgeons to understand which circumstances require intervention. Foreign body ingestions and their management vary based on the specific object ingested as well as the patient population involved (adult or pediatric). The majority of ingested foreign objects will pass through the gastrointestinal tract without intervention. Ten to 20% of cases will require endoscopic removal, and about 1% will require surgical intervention. Similarly, the management of gastric bezoars, which are collections of undigested materials, varies based on the composition of the bezoar. Most cases require endoscopic fragmentation, and very few require surgical intervention.

Thirty-day readmissions following parathyroidectomy: Evidence from the National Readmissions Database, 2013–2014

PURPOSE Parathyroidectomy is one of the most common procedures performed in the United States, and are increasingly being performed safely in the outpatient setting. However, complications from surgery can be life-threatening, and thus an understanding of who may be at risk is essential. We analyzed and compared the risk factors for patients readmitted within 30 days following inpatient parathyroidectomy for primary or secondary hyperparathyroidism. MATERIALS AND METHODS We reviewed the National Readmissions Database from 2013 to 2014 for patients who received inpatient parathyroidectomy for primary or secondary hyperparathyroidism. The primary outcome was non-elective readmission within 30 days. Multivariate logistic regression was used to analyze risk factor odds ratios for readmission. RESULTS 7171 patients underwent inpatient parathyroidectomies in 2013 and 2014. 59.89% of parathyroidectomies were performed for primary hyperparathyroidism, with a 5.6% readmission rate. Most common causes of readmission were septicemia (13.69%), hypocalcemia (12.86%), heart failure (10.79%) and renal failure (9.54%). Having Medicare (OR: 1.71, CI:1.14-2.59, p = .01), Medicaid (OR: 3.24, CI: 2.03-5.17, p < .001), and self-paying (OR: 2.43, CI: 1.11-5.32, p = .02), were associated with increased odds of readmission for those with primary hyperparathyroidism. 21.99% of parathyroidectomies were performed for secondary hyperparathyroidism, with a 19.4% readmission rate. Most common causes of readmission were hypocalcemia (22.88%), hungry bone syndrome (14.38%), electrolyte disorders (13.73%), and renal failure (11.11%). CONCLUSION Patients with secondary hyperparathyroidism are older, poorer and have more comorbidities than patients with primary hyperparathyroidism, and are more likely to be readmitted within 30 days of parathyroidectomy.