Mechanism of glucocerebrosidase activation and dysfunction in Gaucher disease unraveled by molecular dynamics and deep learning.

The lysosomal enzyme glucocerebrosidase-1 (GCase) catalyzes the cleavage of a major glycolipid glucosylceramide into glucose and ceramide. The absence of fully functional GCase leads to the accumulation of its lipid substrates in lysosomes, causing Gaucher disease, an autosomal recessive disorder that displays profound genotype-phenotype nonconcordance. More than 250 disease-causing mutations in GBA1, the gene encoding GCase, have been discovered, although only one of these, N370S, causes 70% of disease. Here, we have used a knowledge-based docking protocol that considers experimental data of protein-protein binding to generate a complex between GCase and its known facilitator protein saposin C (SAPC). Multiscale molecular-dynamics simulations were used to study lipid self-assembly, membrane insertion, and the dynamics of the interactions between different components of the complex. Deep learning was applied to propose a model that explains the mechanism of GCase activation, which requires SAPC. Notably, we find that conformational changes in the loops at the entrance of the substrate-binding site are stabilized by direct interactions with SAPC and that the loss of such interactions induced by N370S and another common mutation, L444P, result in destabilization of the complex and reduced GCase activation. Our findings provide an atomistic-level explanation for GCase activation and the precise mechanism through which N370S and L444P cause Gaucher disease.

Reversal of warfarin-coagulopathy: How to improve plasma transfusion practice in a community hospital setting?

BACKGROUND: Plasma is often given inappropriately to reverse warfarin-induced coagulopathy, wasting health-care resources and exposing the patients to transfusion-associated risks. AIMS: The clinical practice at our institution was evaluated in order to reduce the number of unnecessary plasma transfusions. MATERIALS AND METHODS: Retrospective audit of plasma transfusions was done (July 2014 to June 2015). DESIGN: To improve the clinical practice, a two-prong strategy was implemented: (1) in-service was given to clinicians on the warfarin-reversal guidelines and (2) for a 30-day period, plasma orders were placed on the approval list of the Transfusion Medicine Service. RESULTS: Of the 729 units of plasma, 189 (26% of total) were given for the reversal of warfarin-induced coagulopathy. The medical charts of these patients were reviewed: 46 units of plasma (~25%) were given inappropriately (e.g., patients with minimally elevated international normalized ratio, no evidence of bleeding, and no surgery within 24 h). To check the effectiveness of our intervention, two audits of plasma transfusions were done. During the first audit (January 1-February 29, 2016), 24 patients received plasma to reverse warfarin-coagulopathy. Medical chart review revealed that the vast majority of plasma orders (96.66%) followed the guidelines. A second audit was carried out a year later (January 1-March 31, 2017): during this 3-month period, 47 patients were transfused with plasma for warfarin reversal with a 94% adherence to the guidelines. CONCLUSION: We conclude that plasma transfusion practices may be improved by a combination of education and active enforcement of warfarin reversal guidelines.

CUSHING DISEASE MASQUERADING AS GLAUCOMA.

OBJECTIVE: Glaucoma is a well-recognized side effect of corticosteroids. However, steroid-induced glaucoma typically refers to that caused by exogenous corticosteroid administration. Glaucoma secondary to endogenous overproduction of corticosteroids has only been reported in a few case reports. We aim to bring attention to glaucoma as a rare but important manifestation of endogenous hypercortisolism. METHODS: Patient history, physical exam, laboratory results, and imaging studies were reviewed. RESULTS: We report a case of glaucoma as the initial presentation of Cushing disease (CD). The patient was diagnosed with glaucoma 16 months prior to his endocrinology evaluation. At our initial encounter, the patient had a cushingoid appearance. Levels of 24-hour urinary cortisol and late-night salivary cortisol were elevated. Serum cortisol was not suppressed by 1 mg of dexamethasone overnight, but it was suppressed by 8 mg of dexamethasone. Adrenocorticotropic hormone was also elevated. All other pituitary hormone axes were unremarkable (thyroid-stimulating hormone, free thyroxine, follicle-stimulating hormone, luteinizing hormone, growth hormone, prolactin, and insulin-like growth factor). Pituitary magnetic resonance imaging suggested a small adenoma (2 to 3 mm); therefore, the patient underwent inferior petrosal sinus sampling. The results were consistent with CD. Transsphenoidal resection was performed and final pathology confirmed an adrenocorticotropic hormone-positive adenoma. Hypercortisolism and intraocular pressures improved after the surgery. CONCLUSION: Glaucoma can lead to irreversible blindness if left untreated or uncontrolled. However, endogenous hypercortisolism-induced glaucoma can be reversed with treatment of the underlying CD. Thus, heightened awareness of extraocular manifestations of secondary causes of glaucoma such as endogenous hypercortisolism is necessary in order to promote prompt evaluation and treatment.

Megestrol Acetate-Induced Symptomatic Hypogonadism in a Male Patient.

The hypothalamic-pituitary-adrenal (HPA) axis and the hypothalamic-pituitary-gonadal (HPG) axis are very sensitive and can be affected by external factors like stress, starvation, and medication. Medication-induced suppression of these axes can cause adrenal insufficiency (AI) and hypogonadism. Exogenous glucocorticoid use is the most common cause of iatrogenic AI. Our aim is to bring attention to another broadly prescribed medication, megestrol acetate (MA), as the cause of suppression of both these axes. We report a case of symptomatic hypogonadism and asymptomatic AI in a male patient secondary to MA. The patient presented with decrease in testicular size and erectile dysfunction. His total testosterone and morning cortisol levels were low, but FH, LH, and TSH were normal. His pituitary MRI was unremarkable. Upon discontinuation of MA, the patient's testosterone and cortisol levels normalized and his symptoms resolved. Hypogonadism and AI are known adverse effects of MA, but symptomatic hypogonadism as the primary manifestation has only been reported once in previous literature. Prolonged hypogonadism can lead to sarcopenia, depression, and osteoporosis, while asymptomatic AI carries the risk of becoming overt AI. Thus, heightened awareness of the impact of MA on both these axes is necessary.

Emerging concepts in the epidemiology, pathophysiology, and clinical care of osteoporosis across the menopausal transition.

Bone loss in women accelerates during perimenopause, and continues into old age. To-date, there has been little progress made in stratifying for fracture risk in premenopausal and early postmenopausal women. Epidemiologic data suggests that changes in serum FSH could predict decrements in bone mass during peri- and postmenopause. In bone, FSH stimulates osteoclast formation by releasing osteoclastogenic cytokines. Here, we address the evidence for bone loss across the menopausal transition, discuss strategies for detection and treatment of early postmenopausal osteoporosis, and describe the role FSH plays in physiology and likely in pathophysiology of early postmenopausal bone loss.

Intravenous Drug Abuse by Patients Inside the Hospital: A Cause for Sustained Bacteremia.

Patients with history of intravenous drug abuse are noted to be at risk of several infections including HIV, endocarditis, and other opportunistic infections. We report the case of a patient with sustained Bacillus cereus bacteremia despite use of multiple antibiotic regimens during his inpatient stay. Our case highlights the importance of high suspicion for active drug use inside the hospital in such patients. This is important in order to minimize unnecessary diagnostic workup and provide adequate treatment and safe hospital stay for these patients.

Left Ventricular Aneurysm Presenting as a Late Complication of Childhood Chemotherapy.

Cardiotoxicity is a well known adverse effect of chemotherapy. Multiple cardiac injuries have been reported including cardiomyopathy, pericarditis, myocarditis, angina, arrhythmias, and myocardial infarction. A left ventricular aneurysm due to chemotherapy is a rare and a dangerous complication which is particularly challenging in diagnosis requiring a high index of suspicion and periodic imaging. We present a case of a young Caucasian male with a past medical history of Acute Lymphocytic Leukemia status after chemotherapy during his childhood diagnosed with left ventricular aneurysm several years later.

Persistent Hypoglycemia in Patient with Hodgkin's Disease.

Hypoglycemia is a rare complication of Hodgkin's disease. Several explanations have been postulated but the exact pathophysiology is not well understood. We are presenting a case of newly diagnosed Stage IV Hodgkin's disease that developed persistent and recurrent hypoglycemia despite giving glucagon, repeated 50% dextrose, and D5 and D10 continuous infusion. Hypoglycemia workup showed the C-peptide level to be low. Patient was suspected of having hypoglycemia related to lymphoma and was given a trial of prednisone which resolved the hypoglycemic episodes and made the patient euglycemic for the rest of his hospital stay. The presence of a substance that mimicked the effects of insulin was highly suspected. Several case reports strengthen the hypothesis of an insulin-like growth factor or antibodies secreted by the cancer cells causing hypoglycemia in Hodgkin's disease but none of them have been confirmed. Further investigation is warranted to more clearly define the pathophysiology of persistent hypoglycemia in patients with Hodgkin's disease.