Role of Preoperative Basal Calcitonin Levels in the Timing of Prophylactic Thyroidectomy in Patients With Germline RET Mutations

Background

The American Thyroid Association (ATA) published recommendations for the timing of prophylactic surgery for medullary thyroid carcinoma based on the specific mutation, patient age, family history, and serum calcitonin levels. The aim of this study was to assess the role of preoperative basal calcitonin (prebCt) levels in predicting the presence of medullary carcinoma of the thyroid in patients with RET mutations.

Methods

We conducted a retrospective study in two endocrine surgery departments. Between 1986 and 2012, a total of 32 patients with RET mutations underwent prophylactic thyroidectomy. The patients were stratified into four ATA risk levels: A, B, C, and D.

Results

All of the patients were biologically cured. Microcarcinoma was observed in the final pathology report for four of the 20 patients with normal prebCt (25 %) and for nine of the 12 patients with elevated prebCt (75 %). In the level A group, four patients with normal prebCt and one patient with elevated prebCt presented with microcarcinoma. In the level C group, one patient with normal prebCt and six of the seven patients with elevated prebCt (86 %) presented with microcarcinoma.

Conclusions

PrebCt can predict the presence of microcarcinoma according to surgical pathological analysis. Patients with microcarcinoma can be biochemically and clinically cured using prophylactic thyroidectomy.     

Primary migration of a mini-implant under a functional orthodontic loading

Objectives

The objective of this study was to examine whether cortical bone thickness and bone mineral density (BMD) can explain the primary migration of a mini-implant under a functional orthodontic tangential loading at the early stage following implantation.

Materials and methods

Mini-implants were installed in human mandibular sections. A constant tangential load (2 N) was applied to the mini-implant under hydration. Creep, which is a time-dependent viscoelastic displacement in the bone surrounding the mini-implant, was assessed as the change in displacement during 2 h of loading. The total migration was measured as a maximum displacement that combined an initial elastic displacement and creep. After removal of the mini-implant, all specimens were scanned together by cone beam computed tomography. Cortical bone thickness and BMD were measured for the bone voxels surrounding the implant site.

Results

BMD had significant correlations with the displacement parameters (p?<?0.019), but the cortical bone thickness did not (p?>?0.272). Permanent bone deformation adjacent to the implant was observed to be resulting from substantial creep development under the orthodontic functional loading level.

Conclusions

BMD controls the primary migration of the mini-implant system in mandibular bone. Viscoelastic creep can develop at a small constant functional loading level, leading to migration of the mini-implant.

Clinical relevance

The current results indicated that mini-implant migration can develop under the small level of functional orthodontic load used in clinic. If the active bone remodeling around the mini-implant accelerates the migration, the risk of causing damage in vital organs next to the mini-implant increases.     

Global structural changes of an ion channel during its gating are followed by ion mobility mass spectrometry

Mechanosensitive ion channels are sensors probing membrane tension in all species; despite their importance and vital role in many cell functions, their gating mechanism remains to be elucidated. Here, we determined the conditions for releasing intact mechanosensitive channel of large conductance (MscL) proteins from their detergents in the gas phase using native ion mobility–mass spectrometry (IM-MS). By using IM-MS, we could detect the native mass of MscL from Escherichia coli, determine various global structural changes during its gating by measuring the rotationally averaged collision cross-sections, and show that it can function in the absence of a lipid bilayer. We could detect global conformational changes during MscL gating as small as 3%. Our findings will allow studying native structure of many other membrane proteins.One of the best candidates to explore the gating of mechanosensitive channels is the mechanosensitive channel of large conductance (MscL) from Escherichia coli. The crystal structure of MscL in its closed/nearly closed state from Mycobacterium tuberculosis revealed this channel as a homopentamer (1). Each subunit has a cytoplasmic N- and C-terminal domain as well as two α-helical transmembrane (TM) domains, TM1 and TM2, which are connected by a periplasmic loop. The five TM1 helices form the pore and the more peripheral TM2 helices interact with the lipid bilayer.MscL detects changes in membrane tension invoked by a hypoosmotic shock and couples the tension sensing directly to large conformational changes (1, 2). On the basis of a large body of structural and theoretical data, numerous gating models of MscL have been proposed (3–9). These models agree upon (i) the hydrophobic pore constriction of the channel and (ii) the channel opens by an iris-like rotation—i.e., a tilting and outward movement of transmembrane helices that make the channel wider and shorter (5). This mechanism is supported by patch-clamp (10), disulfide cross-linking (11), FRET spectroscopy (12), and site-directed spin labeling EPR experiments (6, 7), as well as computational studies (13–15). So far, direct experimental results have only been observed for short-range local structural changes, and no measure of the overall global structural changes during channel gating have been reported. Because there is no crystal structure available for the open MscL channel, elucidating overall global structural changes from the onset of channel activation is of utmost importance for our understanding of the gating mechanism of mechanosensitive channels. Here, we provide direct experimental evidence for the key areal changes occurring during channel gating by combining our ability to activate MscL in a controlled manner to different subopen states (16) with a native ion mobility-mass spectrometry (IM-MS) approach.     

Immunosignature system for diagnosis of cancer

Although the search for disease biomarkers continues, the clinical return has thus far been disappointing. The complexity of the body’s response to disease makes it difficult to represent this response with only a few biomarkers, particularly when many are present at low levels. An alternative to the typical reductionist biomarker paradigm is an assay we call an “immunosignature.” This approach leverages the response of antibodies to disease-related changes, as well as the inherent signal amplification associated with antigen-stimulated B-cell proliferation. To perform an immunosignature assay, the antibodies in diluted blood are incubated with a microarray of thousands of random sequence peptides. The pattern of binding to these peptides is the immunosignature. Because the peptide sequences are completely random, the assay is effectively disease-agnostic, potentially providing a comprehensive diagnostic on multiple diseases simultaneously. To explore the ability of an immunosignature to detect and identify multiple diseases simultaneously, 20 samples from each of five cancer cohorts collected from multiple sites and 20 noncancer samples (120 total) were used as a training set to develop a reference immunosignature. A blinded evaluation of 120 blinded samples covering the same diseases gave 95% classification accuracy. To investigate the breadth of the approach and test sensitivity to biological diversity further, immunosignatures of >1,500 historical samples comprising 14 different diseases were examined by training with 75% of the samples and testing the remaining 25%. The average accuracy was >98%. These results demonstrate the potential power of the immunosignature approach in the accurate, simultaneous classification of disease.Cancer is the most likely disease for which an early diagnostic would be immediately beneficial. Unfortunately, finding specific biomarkers, especially for cancer, has been complicated by the fact that biological molecules (RNA, DNA, proteins, or peptides) that are uniquely released by a small tumor into the bloodstream are extremely dilute. Classical biomarker assays are based on one-to-one molecular recognition events to detect one or a few specific analytes that are often measured by antibody–protein interactions. There are three fundamental limitations with this approach, all of which are confounded by the dilution problem alluded to above. The first is that the cross-reactivity of such interactions poses a formidable problem in distinguishing diseases. Biology’s promiscuous use of a limited number of homologous sequences, folds, and domains makes specificity difficult. The second is that diseases such as cancer are themselves heterogeneous, and individual response to disease, at a molecular level, can vary considerably. It is unlikely that this level of complexity can be quantitatively assessed by one or a few specific proteins or metabolites in a way that supports robust diagnosis. Third, many of the biomarkers that have been proposed are of low stability or require substantial preassay purification or preparation; these aspects introduce substantial variation into the measured values (1, 2). As a result, although considerable effort has been put into the development of biomarkers, only a small fraction of candidates make it to clinical practice, and the utility of those that are used is sometimes only modest (3–5). Here, we explore the ability of the immunosignature technology to address the ideal of a simple, comprehensive diagnostic for multiple cancers.An “immunosignature” is the pattern obtained when circulating antibodies in blood are allowed to bind to a large microarray of randomized-sequence peptides affixed to a solid surface (6). Cancers generate neoantigens by virtue of their mutagenic nature, and they tend to release native proteins and biomolecules not normally encountered by the immune system (7–9). These behaviors can elicit an immune response (6, 10, 11). By virtue of the tremendous amplification afforded by B-cell replication (12), the signal elicited by the disease-specific antigens is massively amplified. In fact, a key aspect of the immunosignature assay is that the blood is greatly diluted before application to the array, such that only the antibodies that have been sufficiently amplified give distinct signals (13).Another somewhat counterintuitive aspect of the method is that the peptide sequences used on the microarray are purposefully not chosen to represent the natural antigens of the antibodies produced in response to disease. In fact, in the arrays of 10,000 peptides used in this study, the peptide sequences were generated with a random number generator. This enables the same microarray to be used for diagnosis of any disease. Despite using random-sequence peptides, monoclonal antibodies generated from a wide variety of antigens show specific patterns of binding on these arrays, to both cognate and noncognate sequences (14, 15). Many of the peptides bound by a monoclonal antibody against a known linear epitope have no obvious sequence similarity to that epitope. Most of the peptides thus identified have demonstrated low affinity in solution for the antibody but are retained on the arrays due to avidity created by close spacing of individual peptides (15).An immunosignature of an individual consists of an overlay of the patterns from the binding signals of many of the most prominent circulating antibodies. Some of the binding signals are present in most individuals (whether sick or healthy), and some are unique to an individual, but if the individual has a disease such as a cancer, a subset of the binding signals will be due to disease-associated antigens that are common to most individuals with the disease (16). An important aspect of this approach is that it senses essentially all antibodies raised to the disease and detects each of the antibodies as separable binding patterns composed of unique molecular recognition elements. This differs from, for example, an ELISA, which might sum the contributions of many different antibodies using a single protein, cell, or virus capsid. Again, from a statistical perspective, the high dimensionality of this readout affords much more specificity than could be obtained from a set of cognate sequences or from an array of the native antigens themselves.Not only does the use of highly dilute blood and random peptide sequences in the immunosignature assay paradoxically give rise to improved sensitivity and specificity but these aspects of the assay also result in several other unique benefits of the immunosignature approach. Because of the dilution (1:500 in these studies), blood proteins other than antibodies do not significantly bind to the arrays, meaning that there is no sample preparation involved other than dilution (17). The dilution ensures the assay is sample-sparing. Finally, the assay is disease-agnostic. The arrays can be used for the simultaneous detection and identification of multiple diseases.It is simultaneous detection and identification of multiple diseases with a single assay that underlies the true potential of this approach as a disruptive force in healthcare. This, combined with the fact that serum antibodies are robust to handling (17, 18) such that a drop of blood can be sent dried on filter paper through the mail (17), should enable frequent, inexpensive monitoring for many different diseases. The goal of the current work is to test the multidisease aspect of immunosignatures rigorously. Although the approach has previously been used to discriminate various subtypes of brain cancer (19), it has not yet demonstrated multiplexed cancer diagnosis. Here, we perform a blinded train/test validation study wherein a group of 120 individuals with five different cancers from various geographic regions was used as a training set to define a multicancer signature. The signature predicted the disease status of a test cohort of equal size and composition. To explore the ability of the approach to discriminate between an even larger set of diseases, 1,516 different individuals spanning 14 different disease cohorts plus a diverse cohort of healthy controls were assayed and the ability to distinguish between these diseases was evaluated.     

Management of cervical thoracic duct cyst with cyst-venous anastomosis

INTRODUCTION

Cervical thoracic duct cyst (CTDC) is a rare cause of lateral neck mass. Surgical excision with ligation of the cervical thoracic duct is the current standard for definitive management with symptomatic patients. We report the first case of an alternative method of management performing a cyst venous anastomosis for decompression.

PRESENTATION OF CASE

A 77 year old female presented with a six month history of left arm pain, swelling and a left-sided cystic neck mass. She was treated with cyst-venous anastomosis between the cyst wall and the left internal jugular vein. At two year follow-up, she has had resolution of pain and no recurrence of the mass.

DISCUSSION

Many potential etiologies have been proposed for CTDC, though surgical management of this rare problem has consistently required cyst excision and thoracic duct ligation. Few innovative modes of therapy have been developed to address this problem in a less invasive manor. Maintaining a more natural thoracic duct anatomy decreases the likely of complications associated with duct ligation.

CONCLUSION

Cyst-venous anastomosis for the management of CTDC provides an effective, novel form of treatment which maintains the integrity of the thoracic duct and avoids potential complications associated with duct ligation.     

Pharmacotherapy Choice Is Associated with 2-Year Mortality for Patients with Heart Failure and Reduced Ejection Fraction

Introduction

Factors associated with mortality for patients with heart failure and reduced ejection fraction (HFrEF) are known; however, the association between initial pharmacotherapy (IPT) and mortality is unclear in real-world settings.

Methods

Using a retrospective design and claims database, 14,359 Medicare patients with HFrEF from August 2010 to July 2015 were identified. Index date was first HF claim. IPT was mono- or combo-angiotensin-converting enzyme inhibitor (ACEI), angiotensin II receptor blocker (ARB), beta-blocker (BB), hydralazine–nitrate (HN), and aldosterone antagonist (AA) within 1 year post-index. A multivariable time-dependent Cox model estimated associations between IPT and 2-year all-cause mortality.

Results

Patients’ median age was 76 (70–82) years; 45.1% were female. Within 1 month post-index, 61.4% had IPT, 6.1% started after the first month, and 32.4% had no IPT in the first year. Of IPTs, 47.5% were mono-vasodilators (ACEI, ARB or HN), 23.3% mono-vasodilator + BB, 16.9% mono-BB, and 3.5% triple therapy [(ACEI or ARB) + BB + (HN or AA)]. Two-year mortality rate was 27.9%. Compared to mono-vasodilator therapy, patients initiating triple therapy had 29.3% lower risk of 2-year mortality; those on mono-BB or no IPT had higher mortality risk.

Conclusion

IPT was associated with decreased 2-year mortality risk. Timely consideration of triple IPT therapies may be warranted once HFrEF diagnosis is confirmed.

Funding

Novartis Pharmaceuticals Corp. located in East Hanover, NJ, USA.

     

Ethical considerations of refusing nutrition after stroke

The aim of this article is to analyse and discuss the ethically problematic conflict raised by patients with stroke who refuse nutritional treatment. In analysing this conflict, the focus is on four different aspects: (1) Is nutritional treatment biologically necessary? (2) If necessary, is the reason for refusal a functional disability, lack of appetite or motivation, misunderstanding of the situation or a genuine conflict of values? (3) If the latter, what values are involved in the conflict? (4) How should we deal with the different kinds of refusal of nutritional treatment? We argue that patients' autonomy should be respected as far as possible, while also considering that those who have suffered a stroke might re-evaluate their life as a result of a beneficial prognosis. However, if patients persist with their refusal, health care professionals should force nutritional treatment only when it is clear that the patients will re-evaluate their future life.