From noncoding variant to phenotype via SORT1 at the 1p13 cholesterol locus.

Recent genome-wide association studies (GWASs) have identified a locus on chromosome 1p13 strongly associated with both plasma low-density lipoprotein cholesterol (LDL-C) and myocardial infarction (MI) in humans. Here we show through a series of studies in human cohorts and human-derived hepatocytes that a common noncoding polymorphism at the 1p13 locus, rs12740374, creates a C/EBP (CCAAT/enhancer binding protein) transcription factor binding site and alters the hepatic expression of the SORT1 gene. With small interfering RNA (siRNA) knockdown and viral overexpression in mouse liver, we demonstrate that Sort1 alters plasma LDL-C and very low-density lipoprotein (VLDL) particle levels by modulating hepatic VLDL secretion. Thus, we provide functional evidence for a novel regulatory pathway for lipoprotein metabolism and suggest that modulation of this pathway may alter risk for MI in humans. We also demonstrate that common noncoding DNA variants identified by GWASs can directly contribute to clinical phenotypes.

Cardiovascular complications of anorexia nervosa: A systematic review.

OBJECTIVE: Anorexia nervosa portends the highest mortality among psychiatric diseases, despite primarily being a disease of adolescents and younger adults. Although some of this mortality risk is attributable to suicide, many deaths are likely cardiovascular in etiology. Recent studies suggest that adverse myocardial structural changes occur in this condition, which could underlie the increased mortality. Given limited prevalence of severe anorexia there is a paucity of clinical and autopsy data to discern an exact cause of death. METHODS: Given this background we conducted a systematic review of the medical literature to provide a contemporary summary of the pathobiologic sequelae of severe anorexia nervosa on the cardiovascular system. We sought to elucidate the impact of anorexia nervosa in four cardiovascular domains: structural, repolarization/conduction, hemodynamic, and peripheral vascular. RESULTS: A number of cardiac abnormalities associated with anorexia nervosa have been described in the literature, including pericardial and valvular pathology, changes in left ventricular mass and function, conduction abnormalities, bradycardia, hypotension, and dysregulation in peripheral vascular contractility. Despite the prevalent theory that malignant arrhythmias are implicated as a cause of sudden death in this disorder, data to support this causal relationship are lacking. DISCUSSION: It is reasonable to obtain routine electrocardiography and measurements of orthostatic vital signs in patients presenting with anorexia nervosa. Echocardiography is generally not indicated unless prompted by clinical signs of disease. Admission to an inpatient unit with telemetry monitoring is recommended for patients with severe sinus bradycardia or junction rhythm, marked prolongation of the corrected QT interval, or syncope.

Cefepime-Induced Neurotoxicity Presenting with Nonconvulsive Status Epilepticus Admitted as a Stroke Alert.

BACKGROUND Cefepime-induced neurotoxicity has been described in intensive care units (ICUs) and neuro ICU settings, occurring in patients started on cefepime for management of severe infections and sepsis. Most cases occur within 1 to 10 days after starting the drug. We publish a case that occurred on the general medical ward of a patient who had been on cefepime therapy for 4 weeks prior to admission. The aim of this study was to improve the knowledge of this serious condition to general internists as our patient was being managed on the general medical ward. CASE REPORT A 72-year-old female on prolonged intravenous antibiotics for sacral and pelvic osteomyelitis presented with acute encephalopathy and aphasia in the setting of an acute kidney injury. Due to the acute focal neurologic deficit, she was initially admitted as a stroke alert. After a negative magnetic resonance imaging (MRI) of the brain, an electroencephalogram (EEG) was pursued and showed nonconvulsive status epilepticus (NCSE). NCSE was likely a result of cefepime therapy in the setting of an acute kidney injury. CONCLUSIONS Cefepime-induced neurotoxicity should be suspected in any patient on cefepime therapy who develops acute changes in mental status, myoclonus, or evidence of seizures. Risk factors for the disease include older age, renal dysfunction, critical illness, and inappropriate dosing based upon renal function. A high index of suspicion is required and delays in diagnosis are common as there are frequently multiple possible causes for altered mental status in systemically ill patients requiring treatment with broad-spectrum antibiotics.

Treatments of medical complications of anorexia nervosa and bulimia nervosa.

Inherent to anorexia nervosa and bulimia nervosa are a plethora of medical complications which correlate with the severity of weight loss or the frequency and mode of purging. Yet, the encouraging fact is that most of these medical complications are treatable and reversible with definitive care and cessation of the eating-disordered behaviours. Herein, these treatments are described for both the medical complications of anorexia nervosa and those which are a result of bulimia nervosa.

Hepatic sortilin regulates both apolipoprotein B secretion and LDL catabolism.

Genome-wide association studies (GWAS) have identified a genetic variant at a locus on chromosome 1p13 that is associated with reduced risk of myocardial infarction, reduced plasma levels of LDL cholesterol (LDL-C), and markedly increased expression of the gene sortilin-1 (SORT1) in liver. Sortilin is a lysosomal sorting protein that binds ligands both in the Golgi apparatus and at the plasma membrane and traffics them to the lysosome. We previously reported that increased hepatic sortilin expression in mice reduced plasma LDL-C levels. Here we show that increased hepatic sortilin not only reduced hepatic apolipoprotein B (APOB) secretion, but also increased LDL catabolism, and that both effects were dependent on intact lysosomal targeting. Loss-of-function studies demonstrated that sortilin serves as a bona fide receptor for LDL in vivo in mice. Our data are consistent with a model in which increased hepatic sortilin binds intracellular APOB-containing particles in the Golgi apparatus as well as extracellular LDL at the plasma membrane and traffics them to the lysosome for degradation. We thus provide functional evidence that genetically increased hepatic sortilin expression both reduces hepatic APOB secretion and increases LDL catabolism, providing dual mechanisms for the very strong association between increased hepatic sortilin expression and reduced plasma LDL-C levels in humans.

Antibodies immobilized as arrays to profile protein post-translational modifications in mammalian cells.

Previously, we demonstrated that antibodies printed on a solid support were able to detect protein-protein interaction in mammalian cells. Here we further developed the antibody array system for detecting proteins with various post-translational modifications in mammalian cells. In this novel approach, immunoprecipitated proteins were labeled with fluorescent dye followed by incubation over antibody arrays. Targeted proteins, captured by the antibodies immobilized on PVDF membrane or glass slide, were detected by means of near infrared fluorescent scanner or fluorescent microscopy. To demonstrate the application of the antibody arrays in protein post-translational modifications, we profiled protein tyrosine phosphorylation, ubiquitination, and acetylation in mammalian cells under different conditions. Our results indicate that antibody array technology can provide a powerful means of profiling a large number of proteins with different post-translational modifications in cells.