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1.
Updates in adrenal steroidogenesis inhibitors for Cushing's syndrome - A practical guide.
Varlamov, EV, Han, AJ, Fleseriu, M
Best practice & research. Clinical endocrinology & metabolism. 2021;(1):101490
Abstract
Medical therapy is essential in the management of patients with Cushing's syndrome (CS) when curative surgery has failed, surgery is not feasible, when awaiting radiation effect, and in recurrent cases of CS. Steroidogenesis inhibitors have a rapid onset of action and are effective in reducing hypercortisolism, however, adverse effects, including adrenal insufficiency require very close patient monitoring. Osilodrostat is the only steroidogenesis inhibitor to have been assessed in prospective randomized controlled trials and approved for Cushing's disease (CD) by the US Food and Drug Administration and for CS by the European Medical Agency (EMA). Osilodrostat has been shown to be highly effective at maintaining normal urinary free cortisol in patients with CD. Drugs such as metyrapone, ketoconazole (both EMA approved), and etomidate lack prospective evaluation(s). There is, however, considerable clinical experience and retrospective data that show a very wide efficacy range in treating patients with CS. In the absence of head-to-head comparative clinical trials, therapy choice is determined by the specific clinical setting, risk of adverse events, cost, availability, and other factors. In this review practical points to help clinicians who are managing patients with CS being treated with steroidogenesis inhibitors are presented.
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2.
Coelenterazine-Dependent Luciferases as a Powerful Analytical Tool for Research and Biomedical Applications.
Krasitskaya, VV, Bashmakova, EE, Frank, LA
International journal of molecular sciences. 2020;(20)
Abstract
: The functioning of bioluminescent systems in most of the known marine organisms is based on the oxidation reaction of the same substrate-coelenterazine (CTZ), catalyzed by luciferase. Despite the diversity in structures and the functioning mechanisms, these enzymes can be united into a common group called CTZ-dependent luciferases. Among these, there are two sharply different types of the system organization-Ca2+-regulated photoproteins and luciferases themselves that function in accordance with the classical enzyme-substrate kinetics. Along with deep and comprehensive fundamental research on these systems, approaches and methods of their practical use as highly sensitive reporters in analytics have been developed. The research aiming at the creation of artificial luciferases and synthetic CTZ analogues with new unique properties has led to the development of new experimental analytical methods based on them. The commercial availability of many ready-to-use assay systems based on CTZ-dependent luciferases is also important when choosing them by first-time-users. The development of analytical methods based on these bioluminescent systems is currently booming. The bioluminescent systems under consideration were successfully applied in various biological research areas, which confirms them to be a powerful analytical tool. In this review, we consider the main directions, results, and achievements in research involving these luciferases.
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3.
Methanobactin from methanotrophs: genetics, structure, function and potential applications.
Semrau, JD, DiSpirito, AA, Obulisamy, PK, Kang-Yun, CS
FEMS microbiology letters. 2020;(5)
Abstract
Aerobic methane-oxidizing bacteria of the Alphaproteobacteria have been found to express a novel ribosomally synthesized post-translationally modified polypeptide (RiPP) termed methanobactin (MB). The primary function of MB in these microbes appears to be for copper uptake, but MB has been shown to have multiple capabilities, including oxidase, superoxide dismutase and hydrogen peroxide reductase activities, the ability to detoxify mercury species, as well as acting as an antimicrobial agent. Herein, we describe the diversity of known MBs as well as the genetics underlying MB biosynthesis. We further propose based on bioinformatics analyses that some methanotrophs may produce novel forms of MB that have yet to be characterized. We also discuss recent findings documenting that MBs play an important role in controlling copper availability to the broader microbial community, and as a result can strongly affect the activity of microbes that require copper for important enzymatic transformations, e.g. conversion of nitrous oxide to dinitrogen. Finally, we describe procedures for the detection/purification of MB, as well as potential medical and industrial applications of this intriguing RiPP.
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4.
Angiotensin Receptor Blockers Versus Angiotensin Converting Enzyme Inhibitors for the Treatment of Arterial Hypertension and the Role of Olmesartan.
Omboni, S, Volpe, M
Advances in therapy. 2019;(2):278-297
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Abstract
Blood pressure lowering by all classes of antihypertensive drugs is accompanied by significant reductions of stroke and major cardiovascular (CV) events. Drugs acting on the renin-angiotensin-aldosterone system, such as angiotensin converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), showed similar benefit on major CV events to other antihypertensive medications. In real-world practice, ARBs reduced by 10% the incidence of CV mortality, non-fatal myocardial infarction, non-fatal stroke and provided superior protection against CV events than ACEIs in high-risk patients. Despite similar antihypertensive properties and a favourable safety profile for both ACEIs and ARBs, evidence indicates that patients treated with ARBs have lower rates of withdrawal for adverse events and greater persistence to therapy than those treated with ACEIs. Among ARBs, olmesartan is one of the latest generation compounds introduced in clinical practice for treating hypertension: head-to-head comparative trials suggest that the efficacy of olmesartan is superior to that of commonly prescribed ACEIs (ramipril and perindopril). The drug, administered as a monotherapy or in combination with a dihydropyridine calcium channel blocker or a thiazide diuretic, has proved to be effective in maintaining blood pressure stability over 24 h, with a favourable safety profile and low discontinuation rates. These properties are pivotal for considering olmesartan as a useful antihypertensive agent especially for high-risk patients (e.g. elderly, diabetics, patients with metabolic syndrome).Funding: Article preparation and open access fee were funded by Menarini International Operations Luxembourg S.A. (M.I.O.L.).
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Effect of antihypertensive treatment on 24-h blood pressure variability: pooled individual data analysis of ambulatory blood pressure monitoring studies based on olmesartan mono or combination treatment.
Omboni, S, Kario, K, Bakris, G, Parati, G
Journal of hypertension. 2018;(4):720-733
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Abstract
OBJECTIVE To evaluate the impact of olmesartan alone or combined with one to three antihypertensive drugs on 24-h blood pressure variability (BPV) and on distribution of BP reduction in a pooled individual data analysis of 10 double-blind, randomized, ambulatory BP monitoring (ABPM) studies. METHODS ABPMs were performed before and after 6-12 weeks of treatment with placebo (n = 119), active control monotherapy [n = 1195, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), dihydropyridine calcium channel blockers (DCCBs)] olmesartan monotherapy (n = 1410), active control dual combination [n = 79, DCCB + thiazide diuretic (TD)], olmesartan dual combination (n = 637, DCCB or TD), and triple combination therapy (n = 102, DCCB+TD). 24-h BPV was calculated as unweighted or weighted SD of the mean BP, and average real variability. BP control was assessed by smoothness index and treatment-on-variability index. RESULTS The greatest effect on 24-h systolic BPV/diastolic BPV was observed under olmesartan triple [-2.6/-1.9; -1.9/-1.3; -1.4/-1.3 mmHg] and active control dual combination [-1.8/-1.4; -1.9/-1.5; -1.2/-1.1 mmHg]. Smoothness indexes and treatment-on-variability indexes were significantly (P = 0.0001) higher under olmesartan dual (1.53/1.22, 1.67/1.29, 2.05/1.59), olmesartan triple (2.47/1.85, 2.80/2.06, 3.64/2.67), or active control dual combination (1.70/1.26, 1.85/1.33, 2.29/1.65) than under monotherapies (control: 0.86/0.73, 0.80/0.65, 1.01/0.82; olmesartan: 1.02/0.86, 0.95/0.78, 1.23/1.00). They were also greater in patients receiving high-dose olmesartan monotherapy or high-dose olmesartan dual combination than in the corresponding low-dose group. CONCLUSION Olmesartan plus a DCCB and/or a TD produces a larger, more sustained, and smoother BP reduction than placebo and monotherapies, a desirable feature for a more effective prevention of the cardiovascular consequences of uncontrolled hypertension.
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Pharmacological interventions for the prevention of insufficiency fractures and avascular necrosis associated with pelvic radiotherapy in adults.
van den Blink, QU, Garcez, K, Henson, CC, Davidson, SE, Higham, CE
The Cochrane database of systematic reviews. 2018;(4):CD010604
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Abstract
BACKGROUND Pelvic radiotherapy is a treatment delivered to an estimated 150,000 to 300,000 people annually across high-income countries. Fractures due to normal stresses on weakened bone due to radiotherapy are termed insufficiency fractures. Pelvic radiotherapy-related interruption of the blood supply to the hip is termed avascular necrosis and is another recognised complication. The reported incidences of insufficiency fractures are 2.7% to 89% and risk of developing avascular necrosis is 0.5%. These complications lead to significant morbidity in terms of pain, immobility and consequently risk of infections, pressure sores and mortality. OBJECTIVES To assess the effects of pharmacological interventions for preventing insufficiency fractures and avascular necrosis in adults over 18 years of age undergoing pelvic radiotherapy. SEARCH METHODS We performed electronic literature searches in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and DARE to 19 April 2017. We also searched trial registries. Further relevant studies were identified through handsearching of citation lists of included studies. SELECTION CRITERIA Randomised controlled trials (RCTs) or non RCTs with concurrent comparison groups including quasi-RCTs, cluster RCTs, prospective cohort studies and case series of 30 or more participants were screened. We included studies assessing the effect of pharmacological interventions in adults over 18 years of age undergoing radical pelvic radiotherapy as part of anticancer treatment for a primary pelvic malignancy. We excluded studies involving radiotherapy for bone metastases. We assessed use of pharmacological interventions at any stage before or during pelvic radiotherapy. Interventions included calcium or vitamin D (or both) supplementation, bisphosphonates, selective oestrogen receptor modulators, hormone replacement therapy (oestrogen or testosterone), denosumab and calcitonin. DATA COLLECTION AND ANALYSIS Two review authors independently assessed trial quality and extracted data. We contacted study authors to obtain missing data. Data were to be pooled using the random-effects model if study comparisons were similar, otherwise results were to be reported narratively. MAIN RESULTS We included two RCTs (1167 participants). The first RCT compared zoledronic acid with placebo in 96 men undergoing pelvic radiotherapy for non-metastatic prostate cancer.The second RCT had four treatment arms, two of which evaluated zoledronic acid plus adjuvant androgen suppression compared with androgen suppression only in 1071 men undergoing pelvic radiotherapy for non-metastatic prostate cancer.Both studies were at a moderate to high risk of bias and all evidence was judged to be of very low certainty.The studies provided no evidence on the primary outcomes of the review and provided limited data in relation to secondary outcomes, such that meta-analyses were not possible. Both studies focused on interventions to improve bone health in relation to androgen deprivation rather than radiation-related insufficiency fractures and avascular necrosis. Few fractures were described in each study and those described were not specific to insufficiency fractures secondary to radiotherapy. Both studies reported that zoledronic acid in addition to androgen deprivation and pelvic radiotherapy led to improvements in BMD; however, the changes in BMD were measured and reported differently. There was no available evidence regarding adverse effects. AUTHORS' CONCLUSIONS The evidence relating to interventions to prevent insufficiency fractures and avascular necrosis associated with pelvic radiotherapy in adults is of very low certainty. This review highlights the need for prospective clinical trials using interventions prior to and during radiotherapy to prevent radiation-related bone morbidity, insufficiency fractures and avascular necrosis. Future trials could involve prospective assessment of bone health including BMD and bone turnover markers prior to pelvic radiotherapy. The interventions for investigation could begin as radiotherapy commences and remain ongoing for 12 to 24 months. Bone turnover markers and BMD could be used as surrogate markers for bone health in addition to radiographic imaging to report on presence of insufficiency fractures and development of avascular necrosis. Clinical assessments and patient reported outcomes would help to identify any associated adverse effects of treatment and quality of life outcomes.
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Chronic Myeloid Leukemia Associated Hypercalcemia: A Case Report and Literature Review.
Toro-Tobón, D, Agosto, S, Ahmadi, S, Koops, M, Bruder, JM
The American journal of case reports. 2017;:203-207
Abstract
BACKGROUND Hypercalcemia associated with chronic myeloid leukemia (CML) is an ominous sign. Although rare, several cases have been reported and multiple pathophysiologic mechanisms have been independently proposed. We present a patient case and a literature review of the clinical presentation and mechanisms of CML-associated hypercalcemia. CASE REPORT A 58-year-old male with a past medical history of CML diagnosed six years earlier, presented to the emergency department with one week of acute confusion, disorientation, polyuria, and polydipsia. On physical examination, we observed tachycardia, altered mental status, and dehydration. Blood analysis revealed leukocytosis, thrombocytosis, and marked hypercalcemia (18.6 mg/dL). His chest CT scan showed diffuse lytic lesions and bone destruction concerning for diffuse bone marrow involvement. The patient was diagnosed with hypercalcemia in the context of a CML blast phase. Treatment with hydration, calcitonin, and zoledronic acid lead to control of his symptoms and normalization of his serum calcium levels. After discharged, the patient was maintained on palliative treatment and zoledronic acid management without new episodes of hypercalcemia. However, eight months later, the patient died. CONCLUSIONS Evidence from the literature demonstrates a highly variable clinical presentation of CML-associated hypercalcemia, commonly occurring during an accelerated or a blast phase, and associated with poor survival. Multiple mechanisms could be involved and are not exclusive of each other. Better understanding of the pathophysiologic mechanisms involved in CML-associated hypercalcemia could lead to improvement in clinical and laboratory evaluation of these patients and be the foundation for the development of better management strategies and possibly target-directed therapy to positively improve prognosis.
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8.
Methanobactins: from genome to function.
Dassama, LM, Kenney, GE, Rosenzweig, AC
Metallomics : integrated biometal science. 2017;(1):7-20
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Abstract
Methanobactins (Mbns) are ribosomally produced, post-translationally modified peptide (RiPP) natural products that bind copper with high affinity using nitrogen-containing heterocycles and thioamide groups. In some methanotrophic bacteria, Mbns are secreted under conditions of copper starvation and then re-internalized as a copper source for the enzyme particulate methane monooxygenase (pMMO). Genome mining studies have led to the identification and classification of operons encoding the Mbn precursor peptide (MbnA) as well as a number of putative transport, regulatory, and biosynthetic proteins. These Mbn operons are present in non-methanotrophic bacteria as well, suggesting a broader role in and perhaps beyond copper acquisition. Genetic and biochemical studies indicate that specific operon-encoded proteins are involved in Mbn transport and provide insight into copper-responsive gene regulation in methanotrophs. Mbn biosynthesis is not yet understood, but combined analysis of Mbn structures, MbnA sequences, and operon content represents a powerful approach to elucidating the roles of specific biosynthetic enzymes. Future work will likely lead to the discovery of unique pathways for natural product biosynthesis and new mechanisms of microbial metal homeostasis.
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Adding Water to the Mill: Olmesartan-Induced Collagenous Sprue-A Case Report and Brief Literature Review.
Desruisseaux, C, Bensoussan, M, Désilets, E, Tran, HK, Arcand, R, Poirier, G, Wisniewski, A, Manière, T
Canadian journal of gastroenterology & hepatology. 2016;:4837270
Abstract
Collagenous sprue (CS) is a distinct clinicopathological disorder histologically defined by a thickened subepithelial band (Freeman, 2011). It is a rare condition which has been recently observed in a significant proportion of sprue-like enteropathy associated with olmesartan, a novel entity described by Rubio-Tapia et al. in 2012. CS is historically associated with a poor prognosis (Marthey et al., 2014). However, histological and clinical improvements have been described in most studies with concomitant usage of corticosteroids and/or gluten-free diet (Marthey et al., 2014). We report a unique case of olmesartan-induced collagenous sprue in a 79-year-old man that showed complete histological and clinical remission with the sole withdrawal of the incriminating drug. The literature on this topic is briefly reviewed.
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Emerging treatments in neurogastroenterology: eluxadoline - a new therapeutic option for diarrhea-predominant IBS.
Lacy, BE
Neurogastroenterology and motility. 2016;(1):26-35
Abstract
BACKGROUND Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder worldwide. The global prevalence of IBS is estimated to be as high as 15%. For many patients, IBS is a chronic disorder which can significantly reduce quality of life. Just as important as the effects on any one individual, IBS also places a significant impact on the population as a whole with its negative effects on the health care system. Irritable bowel syndrome is categorized into one of three main categories: IBS with diarrhea, IBS with constipation, and IBS with mixed bowel habits. Patients with diarrhea-predominant IBS (IBS-D) comprise a substantial proportion of the overall IBS population. A number of therapeutic options exist to treat the symptoms of abdominal pain, bloating, diarrhea, and fecal urgency, including non-pharmacologic therapies such as dietary changes and probiotics, or pharmacologic therapies such as loperamide and alosetron. However, many patients have persistent symptoms despite these therapies. This unmet need led to the development of eluxadoline, a mu-opioid receptor agonist/delta-opioid receptor antagonist/kappa-receptor agonist. Approved by the FDA in May 2015, this medication shows promise in the treatment of diarrhea-predominant IBS for both men and women. PURPOSE This monograph will briefly review the impact of IBS, discuss current treatments for IBS-D, and then focus on the pharmacology, clinical efficacy and safety of eluxadoline. Potential mechanisms related to rare events of acute pancreatitis or elevated liver tests will be discussed.