The Drosophila F-box protein Fbxl7 binds to the protocadherin fat and regulates Dachs localization and Hippo signaling.

The Drosophila protocadherin Fat (Ft) regulates growth, planar cell polarity (PCP) and proximodistal patterning. A key downstream component of Ft signaling is the atypical myosin Dachs (D). Multiple regions of the intracellular domain of Ft have been implicated in regulating growth and PCP but how Ft regulates D is not known. Mutations in Fbxl7, which encodes an F-box protein, result in tissue overgrowth and abnormalities in proximodistal patterning that phenocopy deleting a specific portion of the intracellular domain (ICD) of Ft that regulates both growth and PCP. Fbxl7 binds to this same portion of the Ft ICD, co-localizes with Ft to the proximal edge of cells and regulates the levels and asymmetry of D at the apical membrane. Fbxl7 can also regulate the trafficking of proteins between the apical membrane and intracellular vesicles. Thus Fbxl7 functions in a subset of pathways downstream of Ft and links Ft to D localization

Glucuronides in the gut: Sugar-driven symbioses between microbe and host

The intestinal milieu is astonishingly complex and home to a constantly changing mixture of small and large molecules, along with an abundance of bacteria, viral particles, and eukaryotic cells. Such complexity makes it difficult to develop testable molecular hypotheses regarding host-microbe interactions. Fortunately, mammals and their associated gastrointestinal (GI) microbes contain complementary systems that are ideally suited for mechanistic studies. Mammalian systems inactivate endobiotic and xenobiotic compounds by linking them to a glucuronic acid sugar for GI excretion. In the GI tract, the microbiota express β-glucuronidase enzymes that remove the glucuronic acid as a carbon source, effectively reversing the actions of mammalian inactivation. Thus, by probing the actions of microbial β-glucuronidases, and by understanding which substrate glucuronides they process, molecular insights into mammalian-microbial symbioses may be revealed amid the complexity of the intestinal tract. Here, we focus on glucuronides in the gut and the microbial proteins that process them

THE STRUCTURE, FUNCTION, AND INHIBITION OF GUT BACTERIAL β-GLUCURONIDASES

The human gut microbiome is one of the most biochemically rich ecosystems in nature, housing approximately 1000 bacterial species, tens of trillions of cells, and millions of genes. Gut microbes are intimately associated with health outcomes that range from diabetes to depression, yet we have only begun to understand the chemical and biological mechanisms the gut microbiome utilizes to impact host health. One space of this biochemical dark matter is gut bacterial β-glucuronidases (GUSs), glycoside hydrolases that metabolize a myriad of glucuronides in the human gut associated with the dose-limiting toxicities of essential therapeutics. Here we show our efforts to characterize and inhibit gut bacterial GUSs. Structure- and function-guided analysis of GUS genes from the Human Microbiome Project Stool Sample Database revealed three GUSs in a single gut microbe, enabled the discovery of a family of GH2 β-galacturonidases (GalAses) and hybrid GH2 GUS/GalAses, and unearthed a family of novel FMN-binding GUSs in the human gut. Structurally, gut bacterial GUSs demonstrate remarkable diversity for a single enzyme family, in which tertiary structure is conserved, but quaternary structure is highly diverse and a key predictor of substrate specificity. Lastly, we determined the mechanism and performed a structure-activity-relationship of piperazine-containing GUS inhibitors. Inhibition by piperazine-containing inhibitors proceeds via a unique substrate-dependent mechanism that appears to trap GUS during catalysis. We further show that piperazine-containing approved drugs act via the same mechanism, suggesting that approved drugs have off targets in the gut microbiome. Taken together, the work outlined in this dissertation advances our understanding of the structure, function, and inhibition of gut bacterial GUSs and raises many questions about the core function of bacterial GUS in host physiology.Doctor of Philosoph

Infantile spasms (West syndrome): update and resources for pediatricians and providers to share with parents

Background Infantile spasms (IS; West syndrome) is a severe form of encephalopathy that typically affects infants younger than 2 years old. Pediatricians, pediatric neurologists, and other pediatric health care providers are all potentially key early contacts for families who have an infant with IS. The objective of this article is to assist pediatric health care providers in the detection of the disease and in the counseling and guidance of families who have an infant with IS. Methods Treatment guidelines, consensus reports, and original research studies are reviewed to provide an update regarding the diagnosis and treatment of infants with IS. Web sites were searched for educational and supportive resource content relevant to providers and families of patients with IS. Results Early detection of IS and pediatrician referral to a pediatric neurologist for further evaluation and initiation of treatment may improve prognosis. Family education and the establishment of a multidisciplinary continuum of care are important components of care for the majority of patients with IS. The focus of the continuum of care varies across diagnosis, initiation of treatment, and short- and long-term needs. Several on-line educational and supportive resources for families and caregivers of patients with IS were identified. Conclusions Given the possibility of poor developmental outcomes in IS, including the emergence of other seizure disorders and cognitive and developmental problems, early recognition, referral, and treatment of IS are important for optimal patient outcomes. Dissemination of and access to educational and supportive resources for families and caregivers across the lifespan of the child with IS is an urgent need. Pediatric health care providers are well positioned to address these needs

How should children with West syndrome be efficiently and accurately investigated? Results from the National Infantile Spasms Consortium

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111205/1/epi12951.pd

A Comparison of Rectal Diazepam Gel and Placebo for Acute Repetitive Seizures

ABSTRACT Background Acute repetitive seizures are readily recognizable episodes involving increased seizure frequency. Urgent treatment is often required. Rectal diazepam gel is a promising therapy. Methods We conducted a randomized, doubleblind, parallel-group, placebo-controlled study of home-based treatment for acute repetitive seizures. Patients were randomly assigned to receive either rectal diazepam gel, at doses ranging from 0.2 to 0.5 mg per kilogram of body weight on the basis of age, or placebo. Children received one dose at the onset of acute repetitive seizures and a second dose four hours later. Adults received three doses — one dose at onset, and two more doses 4 and 12 hours after onset. Treatment was administered by a care giver, such as a parent, who had received special training. The number of seizures after the first dose was counted for 12 hours in children and for 24 hours in adults. Results Of 125 study patients (64 assigned to diazepam and 61 to placebo) with a history of acute repetitive seizures, 91 (47 children and 44 adults) were treated for an exacerbation of seizures during the study period. Diazepam treatment was superior to placebo with regard to the outcome variables related to efficacy: reduced seizure frequency (P\u3c0.001) and improved global assessment of treatment outcome by the care giver (frequency and severity of seizures and drug toxicity) (P\u3c0.001). Post hoc analysis showed diazepam to be superior to placebo in reducing seizure frequency in both children (P\u3c0.001) and adults (P=0.02), but only in children was it superior with regard to improvement in global outcome (P\u3c0.001). The time to the first recurrence of seizures after initial treatment was longer for the patients receiving diazepam (P\u3c0.001). Thirty-five patients reported at least one adverse effect of treatment; somnolence was the most frequent. Respiratory depression was not reported. Conclusions Rectal diazepam gel, administered at home by trained care givers, is an effective and welltolerated treatment for acute repetitive seizures. (N Engl J Med 1998;338:1869-75.

Autoregulation of Sinorhizobium meliloti exoR gene expression

The successful nitrogen-fixing symbiosis between the Gram-negative soil bacterium Sinorhizobium meliloti and its leguminous plant host alfalfa (Medicago sativa) requires the bacterial exopolysaccharide succinoglycan. Succinoglycan and flagellum production, along with the ability to metabolize more than 20 different carbon sources and control the expression of a large number of S. meliloti genes, is regulated by the ExoR–ExoS/ChvI signalling pathway. The ExoR protein interacts with and suppresses the sensing activities of ExoS, the membrane-bound sensor of the ExoS/ChvI two-component regulatory system. Here we show that exoR expression is clearly upregulated in the absence of any functional ExoR protein. This upregulation was suppressed by the presence of the wild-type ExoR protein but not by a mutated ExoR protein lacking signal peptide. The levels of exoR expression could be directly modified in real time by changing the levels of total ExoR protein. The expression of exoR was also upregulated by the constitutively active sensor mutation exoS96, and blocked by two single mutations, exoS* and exoSsupA, in the ExoS sensing domain. Presence of the wild-type ExoS protein further elevated the levels of exoR expression in the absence of functional ExoR protein, and reversed the effects of exoS96, exoS* and exoSsupA mutations. Altogether, these data suggest that ExoR protein autoregulates exoR expression through the ExoS/ChvI system, allowing S. meliloti cells to maintain the levels of exoR expression based on the amount of total ExoR protein

Clinical efficacy and safety of lamotrigine monotherapy in newly diagnosed pediatric patients with epilepsy

Purpose : To verify the efficacy and safety of lamotrigine (LTG) monotherapy in newly diagnosed children with epilepsy. Methods : We prospectively enrolled 148 children who had undergone LTG monotherapy at our institution between September 2002 and June 2009. Twenty-nine patients were excluded: 19 due to incomplete data and 10 were lost to follow up. The data of the remaining 119 patients was analyzed. Results : We enrolled 119 pediatric epilepsy patients (aged 2.8-19.3 years&#59; 66 males and 53 females) in this study. Out of 119 patients, 29 (25.2%) had generalized epilepsy and 90 (74.8%) had partial epilepsy. The responses of seizure reduction were as follows: Seizure freedom (no seizure attack for at least 6 months) in 87/111 (78.4%, n=111) patients&#59; partial response (reduced seizure frequency compared to baseline) in 13 (11.7%) patients&#59; and persistent seizure in 11 (9.9%) patients. The seizure freedom rate was in 81.6% in patients with partial seizure (75.9% for complex partial seizure and 90.9% for benign rolandic epilepsy) and 44.8% in patients with generalized epilepsy (30.0% for absence seizure, 35.7% for juvenile myoclonic epilepsy patients, and 100.0% for idiopathic generalized epilepsy patients). Adverse reactions were reported in 17 (14.3%) patients, and 8 patients (6.7%) discontinued LTG because of rash and tic. No patient experienced severe adverse reaction such as Stevens-Johnson syndrome. Conclusion : LTG showed excellent therapeutic response and had few significant adverse effects. Our findings report may contribute in promoting the use of LTG monotherapy in epileptic children