How Stickiness Can Speed Up Diffusion in Confined Systems

The paradigmatic model for heterogeneous media used in diffusion studies is built from reflecting obstacles and surfaces. It is well known that the crowding effect produced by these reflecting surfaces slows the dispersion of Brownian tracers. Here, using a general adsorption desorption model with surface diffusion, we show analytically that making surfaces or obstacles attractive can accelerate dispersion. In particular, we show that this enhancement of diffusion can exist even when the surface diffusion constant is smaller than that in the bulk. Even more remarkably, this enhancement effect occurs when the effective diffusion constant, when restricted to surfaces only, is lower than the effective diffusivity with purely reflecting boundaries. We give analytical formulas for this intriguing effect in periodic arrays of spheres as well as undulating microchannels. Our results are confirmed by numerical calculations and Monte Carlo simulations.

Effective diffusivity of Brownian particles in a two dimensional square lattice of hard disks

We revisit the classic problem of the effective diffusion constant of a Brownian particle in a square lattice of reflecting impenetrable hard disks. This diffusion constant is also related to the effective conductivity of non-conducting and infinitely conductive disks in the same geometry. We show how a recently derived Green's function for the periodic lattice can be exploited to derive a series expansion of the diffusion constant in terms of the disk's volume fraction φ. Second, we propose a variant of the Fick-Jacobs approximation to study the large volume fraction limit. This combination of analytical results is shown to describe the behavior of the diffusion constant for all volume fractions.

Assessment of The Bethesda System for Reporting Thyroid Cytopathology

OBJECTIVES

Long-term follow-up is important for determining performance characteristics of thyroid fine-needle aspiration (FNA).

METHODS

Histologic or 3 or more years of clinical follow-up was used to calculate performance characteristics of thyroid FNA before and after implementation of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). The impact of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) classification was also investigated.

RESULTS

Follow-up was obtained for 1,277/1,134 and 1,616/1,393 aspirates/patients (median clinical follow-up, 9.9 and 4.4 years, pre- and post-TBSRTC, respectively). Nondiagnostic, suspicious for follicular neoplasm, and suspicious for malignancy (SFM) diagnoses decreased and benign diagnoses increased post-TBSRTC, while atypical rate remained less than 1%. Negative predictive value for benign nodules and positive predictive value (PPV) for SFM increased significantly. Eleven nodules were reclassified as NIFTP, slightly decreasing PPV/risk of malignancy (ROM).

CONCLUSIONS

Appropriate ROM for thyroid FNA can be achieved through application of TBSRTC terminology with minimal use of atypical category.

Patients' knowledge about the outcomes of thyroid biopsy: a patient survey

PURPOSE

Fine-needle aspiration biopsy of the thyroid is an increasingly common outpatient procedure. Patients are counseled about the indications and risks of this procedure and informed consent is obtained. We aimed to assess the extent to which patients acquired necessary knowledge during this process.

METHODS

Survey study conducted in a thyroid nodule clinic at a referral center. Adult patients who had just undergone a thyroid biopsy were asked to complete a survey, including eight questions regarding the indications and potential outcomes of thyroid biopsy. The main outcome of the study was to assess the patients' knowledge based on the response to each individual survey question.

RESULTS

Two-hundred and ninety-seven patients were eligible, of which 196 (66%) completed the survey: most were women (76%), had adequate reading health literacy (95%) and a mean age of 58 years. Although 86% of patients correctly identified evaluation for thyroid cancer as the main indication for their biopsy, 56% were not aware of the likelihood of this diagnosis. Almost all (>90%) of respondents knew that results could be benign or malignant; fewer were aware of non-diagnostic (71%) or indeterminate (68%) outcomes, or of the need for additional diagnostic testing after the biopsy (33%).

CONCLUSIONS

After undergoing thyroid biopsy, a high proportion of well-educated patients remained unaware of their risk for thyroid cancer, potential outcomes, and downstream consequences of their biopsy. This quality gap raises the possibility that informed consent procedures that meet legal standards may leave patients undergoing thyroid biopsy paradoxically uninformed.

Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors

OBJECTIVE

To characterize large adrenal tumors (≥4 cm in diameter) and to identify features associated with malignancy.

PATIENTS AND METHODS

We investigated the clinical, biochemical, and imaging characteristics in a large retrospective single-center cohort of patients with adrenal tumors of 4 cm or more in diameter during the period of January 1, 2000, through December 31, 2014.

RESULTS

Of 4085 patients with adrenal tumors, 705 (17%) had adrenal masses measuring 4 cm or more in diameter; of these, 373 (53%) were women, with a median age of 59 years (range, 18-91 years) and median tumor size of 5.2 cm (range, 4.0-24.4 cm). Underlying diagnoses were adrenocortical adenomas (n=216 [31%]), pheochromocytomas (n=158 [22%]), other benign adrenal tumors (n=116 [16%]), adrenocortical carcinomas (n=88 [13%]), and other malignant tumors (n=127 [18%]). Compared with benign tumors, malignant tumors were less frequently diagnosed incidentally (45.5% vs 86.7%), were larger (7 cm [range, 4-24.4 cm] vs 5 cm [range, 4-20 cm]), and had higher unenhanced computed tomographic (CT) attenuation (34.5 Hounsfield units [HU] [range, 14.1-75.5 HU] vs 11.5 HU [range, -110 to 71.3 HU]; P<.001). On multivariate analysis, older age at diagnosis, male sex, nonincidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were all found to be statistically significant predictors of malignancy.

CONCLUSION

The prevalence of malignancy in patients with adrenal tumors of 4 cm or more in diameter was 31%. Older age, male sex, nonincidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were associated with an increased risk for malignancy. Clinical context should guide management in patients with adrenal tumors of 4 cm or more in diameter.

Prevalence and predictors of thyroid functional abnormalities in newly diagnosed AL amyloidosis

BACKGROUND

Data on the effect of systemic immunoglobulin light chain amyloidosis (AL amyloidosis) on thyroid function are limited.

OBJECTIVE

To assess the prevalence of hypothyroidism in AL amyloidosis patients and determine its predictors.

METHODS

1142 newly diagnosed AL amyloidosis patients were grouped based on the thyroid-stimulating hormone (TSH) measurement at diagnosis: hypothyroid group (TSH above upper normal reference; >5 mIU L^-1 ; n = 217, 19% of study participants) and euthyroid group (n = 925, 81%). Predictors for hypothyroidism were assessed in a binary multivariate model. Survival between groups was compared using the log-rank test and a multivariate analysis.

RESULTS

Patients with hypothyroidism were older, more likely to present with renal and hepatic involvement and had a higher light chain burden compared to patients in the euthyroid group. Higher proteinuria in patients with renal involvement and lower albumin in patients with hepatic involvement were associated with hypothyroidism. In a binary logistic regression model, age ≥65 years, female sex, renal involvement, hepatic involvement, kappa light chain restriction and amiodarone use were independently associated with hypothyroidism. Ninety-three per cent of patients in the hypothyroid group with free thyroxine measurement had normal values, consistent with subclinical hypothyroidism. Patients in the hypothyroid group had a shorter survival compared to patients in the euthyroid group (4-year survival 36% vs 43%; P = 0.008), a difference that was maintained in a multivariate analysis.

CONCLUSION

A significant proportion of patients with AL amyloidosis present with hypothyroidism, predominantly subclinical, which carries a survival disadvantage. Routine assessment of TSH in these patients is warranted.

Universal time-dependent dispersion properties for diffusion in a one-dimensional critically tilted potential

We consider the time-dependent dispersion properties of overdamped tracer particles diffusing in a one-dimensional periodic potential under the influence of an additional constant tilting force F. The system is studied in the region where the force is close to the critical value F_{c} at which the barriers separating neighboring potential wells disappear. We show that, when F crosses the critical value, the shape of the mean-square displacement (MSD) curves is strongly modified. We identify a diffusive regime at intermediate-time scales with an effective diffusion coefficient which is much larger than the late-time diffusion coefficient for F>F_{c}, whereas for F<F_{c} the late-time and intermediate-time diffusive regimes are indistinguishable. Explicit asymptotic regimes for the MSD curves are identified at all time scales.

Risk of Malignancy in Thyroid Nodules with Non-Diagnostic Fine-Needle Aspiration: A Retrospective Cohort Study

BACKGROUND

Fine-needle aspiration (FNA) of thyroid nodules is commonly performed, and despite the use of ultrasound (US) guidance, the rate of non-diagnostic FNAs is still significant. The risk of malignancy of thyroid nodules with a non-diagnostic FNA is not clearly defined. However, most studies exclude the majority of patients without a repeat biopsy or surgery, thus increasing the likelihood of selection bias. The aims of this study were to determine the malignancy risk in nodules with an initial non-diagnostic FNA, and to identify the factors associated with malignancy.

METHODS

This was a retrospective cohort study of patients with thyroid nodules who underwent US-guided FNA between 2004 and 2010 and had a non-diagnostic result. Patients were followed until confirmatory diagnosis of the nature of the nodule was made. The outcome of malignant or benign disease was based on one of the following: (i) final surgical pathology following thyroidectomy; (ii) repeat biopsy; (iii) clinically, based on repeat ultrasound performed at least three years following biopsy; or (iv) report of thyroid status for patients without follow-up visits contacted by mail.

RESULTS

There were 699 nodules from 665 patients included. The mean age was 59 ± 15 years, and 71.7% were women. There was complete follow-up of 495 nodules. After a median follow-up of 2.7 years, thyroid cancer was found in 15 nodules. The prevalence of malignancy was 3% (15/495). The presence of nodular calcifications was the strongest predictor of thyroid malignancy (odds ratio 5.03 [confidence interval 1.8-14.7]). Initial nodule size was inversely associated with malignancy (odds ratio 0.55 [confidence interval 0.28-0.93]). However, the 193 patients without follow-up had smaller nodules compared with those included in the analysis. None of the patients with repeatedly non-diagnostic results were diagnosed with thyroid cancer at follow-up.

CONCLUSION

The prevalence of thyroid cancer in nodules with non-diagnostic results is lower than the malignancy rate in thyroid nodules in general, but not negligible. They should be followed as per guidelines with heightened suspicion for nodules containing calcifications. Nodules with repeatedly non-diagnostic FNA results especially in the absence of calcifications have a low risk of malignancy and may be observed.

LINGUAL THYROID: 35-YEAR EXPERIENCE AT A TERTIARY CARE REFERRAL CENTER

OBJECTIVE

Lingual thyroid (LT) results from a developmental abnormality due to failure of the thyroid gland to descend to its pretracheal position. Given the low incidence of this disease, standardized management recommendations are lacking. We aimed to describe our institution's experience in LT management and to suggest a practice algorithm.

METHODS

We conducted a retrospective review of LT diagnosed at Mayo Clinic, Rochester, Minnesota, between 1976 and 2010. Demographics, clinical presentation, laboratory data, treatment received, and outcomes were collected.

RESULTS

We identified 29 patients with LT. Eighty-three percent were female; age at diagnosis ranged from 2 weeks to 68 years. Almost one-third of patients were symptomatic, with the most common symptoms being cough and hoarseness. The diagnosis of LT was incidental in 9 patients (31%). Seventy-two percent of patients developed hypothyroidism. Levothyroxine was the treatment of choice, followed by thyroidectomy. Two asymptomatic euthyroid patients were followed without any intervention.

CONCLUSION

Management of patients with LT should be individualized and guided by the patient's symptoms and thyroid hormone status.

Kubo formulas for dispersion in heterogeneous periodic nonequilibrium systems

We consider the dispersion properties of tracer particles moving in nonequilibrium heterogeneous periodic media. The tracer motion is described by a Fokker-Planck equation with arbitrary spatially periodic (but constant in time) local diffusion tensors and drifts, eventually with the presence of obstacles. We derive a Kubo-like formula for the time-dependent effective diffusion tensor valid in any dimension. From this general formula, we derive expressions for the late time effective diffusion tensor and drift in these systems. In addition, we find an explicit formula for the late finite-time corrections to these transport coefficients. In one dimension, we give a closed analytical formula for the transport coefficients. The formulas derived here are very general and provide a straightforward method to compute the dispersion properties in arbitrary nonequilibrium periodic advection-diffusion systems.

Development and Pilot Testing of an Encounter Tool for Shared Decision Making About the Treatment of Graves' Disease

BACKGROUND

The best treatment option for patients with Graves' disease (GD) depends on each person's situation and how the differences between the treatment options matter to them in bringing resolution to their illness. The objective of this study was to develop and test an encounter decision tool (GD Choice) for patients and clinicians to engage in shared decision making about the treatment of GD.

METHODS

GD Choice was developed using an iterative process based on the principles of interaction design and participatory action research. To evaluate the impact of the tool, a controlled before-after study was conducted, assessing the use of GD Choice versus usual care (UC).

RESULTS

Sixty-eight patients were enrolled, 37 to UC and 31 to GD Choice. At baseline, the groups were similar. Treatment discussion length was similar in both arms. After their visit, patients in both groups had similar knowledge about the options, except for GD Choice patients knowing significantly more about the complications of treatment (correctly answered by 83% vs. 55%; p = 0.04). Compared with UC, patients in the GD Choice arm had greater involvement in decision making observed on video recordings of clinical encounters (mean OPTION scale score, 35% vs. 30%; p = 0.02), but reported similar levels of decisional comfort and participation in shared decision making.

CONCLUSIONS

GD Choice increases engagement in the decision-making process and knowledge regarding intervention complications without increasing the length of consultation. These promising results support the conduct of a randomized trial of GD Choice versus UC in a large multicenter trial.

Survey of current approaches to non-diagnostic fine-needle aspiration from solid thyroid nodules

The exact frequency of non-diagnostic ultrasound-guided fine-needle aspiration (USFNA) is unknown. Clinical guidelines suggest repeating USFNA of these nodules. However, there is no specific recommendation or evidence on how and when this re-aspiration should be done. We aim to describe the approaches considered by endocrinologists to yield the highest likelihood of a satisfactory sample in solid thyroid nodules. A cross-sectional survey of The Endocrine Society (TES) and the American Thyroid Association members was conducted between October and December 2012. A total of 694 surveys were returned, 648 (93.4 %) from TES. The responders were equally divided between private and academic settings and had a high degree of expertise. Thirty-nine percent of respondents estimated the frequency of non-diagnostic USFNA to be above 10 %. For its management, 311 (46 %) recommended repeating USFNA in 1-3 months. For a second non-diagnostic USFNA, 216 (31 %) recommend surgery. The most common approaches to increase the diagnostic yield were (1) use of suction with USFNA, 18 % and (2) changing the targeted area of biopsy within the nodule, 18 %. Few considered the patients' preferences as an important driver for the management of non-diagnostic USFNA. Finally, a molecular test for bypassing non-diagnostic USFNA was regarded as the most needed strategy for future research. Variability exists in the management of non-diagnostic USFNA and strategies to increase the diagnostic yield. Testing the suggested strategies in clinical trials and understanding patient's preferences should be supported by guideline panels and funding agencies.

Ultrasound-guided fine-needle aspiration biopsy of thyroid nodules in patients taking novel oral anticoagulants

BACKGROUND

Ultrasound-guided fine-needle aspiration biopsy (USGFNAB) is the most accurate form of evaluation for thyroid nodules. Many patients with thyroid nodules who present for USGFNAB are on anticoagulant agents, including the novel oral anticoagulants (NOACs), for stroke prevention in atrial fibrillation or venous thrombosis prophylaxis.

SUMMARY

There has been at least one retrospective study describing neck USGFNAB bleeding risks in patients on antithrombotic and/or anticoagulant agents. This study concluded that there was no major bleeding risk or increase in hematoma formation in patients on antithrombotic or anticoagulant agents while undergoing USGFNAB, and there was no need to discontinue these agents prior to the procedure. With the emergence of NOACs, further recommendations should be made for patients on these agents who will be undergoing USGFNAB for thyroid nodules. Currently, there are no published studies regarding patients on NOACs who undergo USGFNAB.

CONCLUSIONS

It has previously been established that patients on historical anticoagulant agents do not need to discontinue therapy prior to minor procedures such as needle aspirations or dental procedures. Therefore, in patients currently taking dabigatran, rivaroxaban, or apixaban, it is concluded that it is reasonable and safe to continue the novel oral anticoagulant agents prior to USGFNAB of thyroid nodules without major risk of bleeding. This conclusion is based not only on the fact that minor procedures are considered safe in patients on NOACs, but also because patients on historical anticoagulant agents do not need to discontinue therapy prior to minor procedures.

Symptomatic amyloid goiters: report of five cases

BACKGROUND

Massive amyloid deposition in the thyroid to the point of goiter formation is rare. Here we describe the clinical presentation and outcomes of five patients with amyloid goiter (radiographically confirmed goiter in the context of tissue-proven thyroid amyloidosis) encountered in the past 23 years at our institution.

METHODS

Mayo Clinic archives were searched between 1987 and 2010 for a diagnosis of "thyroid amyloidosis," "amyloid deposits," "amyloid deposition," or "liquid chromatography consistent with amyloid." Inclusion criteria were symptomatic thyromegaly; tissue confirmation of thyroid enlarged by amyloid deposits; and radiologic confirmation of thyroid enlargement.

RESULTS

Five patients were identified who met all inclusion criteria. Amyloid goiter etiology included both primary and secondary amyloidosis, and the goiters ranged in weight from 50 to 130 g each. Diagnosis was made by fine-needle aspiration biopsy with Congo red staining and, if needed, spectrophotometry. All five patients had histories of persistent hoarseness for several years before presentation with compressive symptoms referable to their enlarging thyroids, and all had some degree of thyroid dysfunction (both hypothyroidism and hyperthyroidism) by the end of our follow-up period, which ranged from 5 months to 13 years. Two patients underwent surgical interventions, two were managed conservatively, and in one, the goiter shrank after systemic therapy for amyloidosis.

CONCLUSIONS

Our clinical observations suggest slower goiter progression and a higher prevalence of thyroid dysfunction than previously thought.

Risks and benefits of parathyroid fine-needle aspiration with parathyroid hormone washout

OBJECTIVE

To describe the experience with parathyroid fine-needle aspiration (FNA) and parathyroid hormone (PTH) washout at Mayo Clinic Rochester, Rochester, Minnesota.

METHODS

We retrospectively reviewed all parathyroid FNA procedures performed at Mayo Clinic Rochester between January 2000 and December 2007. Clinical, biochemical, and imaging information, parathyroid FNA procedure, and cytology, surgical, and pathology reports were reviewed, and descriptive statistics, sensitivity, specificity, and positive predictive values are presented.

RESULTS

During the study period, 75 parathyroid FNAs were performed on 74 patients. Cytology results were available for 74 of 75 procedures, with only 31% interpreted as parathyroid cells. PTH washout was performed in 67 patients (91%). Parathyroid FNA with PTH washout had a sensitivity of 84%, specificity of 100%, positive predictive value of 100%, and accuracy of 84%. At the time of surgical treatment, 2 patients were noted to have an inflammatory response from the parathyroid FNA biopsy, 1 had a parathyroid abscess, and 2 had a hematoma. In 3 of these 5 patients, the necessary conversion of a minimally invasive surgical procedure to the standard surgical approach prolonged the surgical time.

CONCLUSION

Parathyroid FNA with PTH washout had a superior performance in comparison with parathyroid scanning or ultrasonography alone. The main limitations of parathyroid FNA with PTH washout are (1) the need for initial identification of a potential parathyroid adenoma by ultrasonography and (2) the number of false-negative results. Parathyroid FNA resulted in complications affecting the surgical procedure in 3 patients.

Hepatic dysfunction in hospitalized patients with acute thyrotoxicosis: a decade of experience

Thyroid disease is a common condition, and thyroid hormone excess or deficiency is known to have wide-ranging effects on a variety of organ systems. Our objective is to describe the magnitude, biochemical features, and clinical characteristics of hepatic abnormalities in patients with acute thyrotoxicosis. We performed a retrospective review of all patients admitted to our institution between January 1, 1998 and December 31, 2008 with a discharge diagnosis of acute thyrotoxicosis excluding iatrogenic causes. The records of these patients were reviewed and data extracted regarding demographic, biochemical, and clinical data particularly relevant to liver function. Fourteen patients were identified of which eleven had liver studies performed. The majority (90.9%) had Graves disease. Nine of eleven patients (81.8%) had some degree of hepatic abnormality. Seven patients (63.6%) had an elevation in one or both transaminases, and two (18.2%) had isolated synthetic dysfunction as manifested as an elevated INR and/or decreased albumin without transaminitis. The mean magnitude of deviation from the normal range was greater in the transaminases as compared to bilirubin, INR, or albumin. Definitive treatment was radioiodine ablation in six cases (54.5%) and surgical thyroidectomy in two cases (18.2%). Noniatrogenic acute thyrotoxicosis requiring hospitalization is a rare condition which is most frequently caused by Graves disease. The majority of patients have disordered liver tests of a highly variable nature, making the recognition of this association important in the care of patients presenting with acute thyrotoxicosis.

Drag forces on inclusions in classical fields with dissipative dynamics

We study the drag force on uniformly moving inclusions which interact linearly with dynamical free field theories commonly used to study soft condensed matter systems. Drag forces are shown to be nonlinear functions of the inclusion velocity and depend strongly on the field dynamics. The general results obtained can be used to explain drag forces in Ising systems and also predict the existence of drag forces on proteins in membranes due to couplings to various physical parameters of the membrane such as composition, phase and height fluctuations.

Development and application of magnetic resonance elastography of the normal and pathological thyroid gland in vivo

PURPOSE

To noninvasively assess the shear stiffness of the thyroid gland in vivo in order to determine whether magnetic resonance elastography (MRE) might hold clinical utility in the diagnosis of thyroid disease.

MATERIALS AND METHODS

Quantitative parametric images of thyroid stiffness in normal volunteers and patients were produced and quantitative stiffness values measured. Average gland stiffness was determined by region of interest analysis of the parametric images. This technique was used to assess stiffness of the thyroid in normal individuals (n = 12), patients with Hashimoto's thyroiditis (HT; n = 5), and patients with a solitary benign (n = 8) or malignant (n = 2) thyroid nodule.

RESULTS

Mean shear modulus of normal thyroid glands was 1.9 +/- 0.6 kPa at 100 Hz and 1.3 +/- 0.5 kPa at 80 Hz, while that of HT glands was 2.8 +/- 0.6 kPa and 1.8 +/- 0.6 kPa at 80 Hz, respectively (P = 0.004 at 100 Hz). Elastographic parameters could not differentiate benign from malignant thyroid nodules in these small sample sizes.

CONCLUSION

We developed a method for the application of MRE to the study of thyroid gland pathology. The results show that the HT gland can be differentiated from normal thyroid. The clinical utility of this imaging modality in the diagnosis and management of thyroid disease awaits further study.

Epidemiology of thyroid nodules

Thyroid nodules are common and are commonly benign. The reported prevalence of nodular thyroid disease depends on the population studied and the methods used to detect nodules. Nodule incidence increases with age, and is increased in women, in people with iodine deficiency, and after radiation exposure. Numerous studies suggest a prevalence of 2-6% with palpation, 19-35% with ultrasound, and 8-65% in autopsy data. With widespread use of sensitive imaging in clinical practice, incidental thyroid nodules are being discovered with increasing frequency. Ultrasonography is the most accurate and cost-effective method for evaluating and observing thyroid nodules. Current ultrasonography machines are relatively inexpensive, sensitive, and easy to operate. Most endocrinologists are now using ultrasound examination in the initial evaluation of a patient with known or suspected thyroid nodule. The management of thyroid incidentalomas is a matter of controversy.

Path integrals for stiff polymers applied to membrane physics

Path integrals similar to those describing stiff polymers arise in the Helfrich model for membranes. We show how these types of path integrals can be evaluated and apply our results to study the thermodynamics of a minority stripe phase in a bulk membrane. The fluctuation induced contribution to the line tension between the stripe and the bulk phase is computed. Also the effective interaction between the interfaces of the two phases can be computed. Explicit forms are given for this Casmir-like interaction in the tensionless case where the two phases have differing bending rigidities.

Hyperthyroidism and atrial myxoma--an intriguing cardio-endocrine association

A 65-year-old woman presented with dyspnea and bilateral leg edema for 1 week, worsening fatigue for 1 month, and a 7-lb weight loss over the last summer. She was clinically and biochemically hyperthyroid. Echocardiography revealed a left atrial myxoma measuring 6.2 x 3.3 cm protruding into the mitral orifice and left ventricle during diastole. She was treated for Graves' disease with Iodine-131. Six weeks later, her left atrial myxoma measuring 10.1 x 6.2 x 2.4 cm was resected. She became euthyroid before surgery and then biochemically hypothyroid 6 weeks after radioiodine treatment, for which she subsequently required thyroxine replacement. Atrial myxomas are the most common primary cardiac neoplasms. At least 5% to 10% can be attributed to Carney's complex. More than two-thirds of patients with Carney's complex develop one or more cardiac myxomas. Although atrial myxomas in Carney's complex are histologically indistinguishable from the sporadic form, their clinical presentation and course is distinct. This is the first case of newly diagnosed Graves' disease that has been reported in association with an atrial myxoma. The features discussed in this article help differentiate between syndromic and sporadic atrial myxomas.

Membrane perturbation by an external electric field: a mechanism to permit molecular uptake

Electropermeabilisation is a well established physical method, based on the application of electric pulses, which induces the transient permeabilisation of the cell membrane. External molecules, otherwise nonpermeant, can enter the cell. Electropermeabilisation is now in use for the delivery of a large variety of molecules, as drugs and nucleic acids. Therefore, the method has great potential in the fields of cancer treatment and gene therapy. However many open questions about the underlying physical mechanisms involved remain to be answered or fully elucidated. In particular, the induced changes by the effects of the applied field on the membrane structure are still far from being fully understood. The present review focuses on questions related to the current theories, i.e. the basic physical processes responsible for the electropermeabilisation of lipid membranes. It also addresses recent findings using molecular dynamics simulations as well as experimental studies of the effect of the field on membrane components.

Fluctuation-induced interactions between domains in membranes

We study a model lipid bilayer composed of a mixture of two incompatible lipid types which have a natural tendency to segregate in the absence of membrane fluctuations. The membrane is mechanically characterized by a local bending rigidity kappa(phi) which varies with the average local lipid composition phi. We show, in the case where kappa varies weakly with phi, that the effective interaction between lipids of the same type either can be everywhere attractive or can have a repulsive component at intermediate distances greater than the typical lipid size. When this interaction has a repulsive component, it can prevent macrophase separation and lead to separation in mesophases with a finite domain size. This effect could be relevant to certain experimental and numerical observations of mesoscopic domains in such systems.

Renormalization of membrane rigidity by long-range interactions

We consider the renormalization of the bending and Gaussian rigidity of model membranes induced by long-range interactions between the components making up the membrane. In particular we analyze the effect of a finite membrane thickness on the renormalization of the bending and Gaussian rigidity by long-range interactions. Particular attention is paid to the case where the interactions are of a van der Waals type.

Thermal Casimir effect in lipid bilayer tubules

We calculate the thermal Casimir effect for a dielectric tube of radius R and thickness delta formed from a membrane in water. The method uses a field-theoretic approach in the grand canonical ensemble. The leading contribution to the Casimir free energy behaves as -k(B)TLkappa(c)/R giving rise to an attractive force which tends to contract the tube. We find that kappa(c) approximately 0.3 for the case of typical lipid membrane t tubules. We conclude that except in the case of a very soft membrane this force is insufficient to stabilize such tubes against the bending stress which tends to increase the radius.

Resummed two-loop calculation of the disjoining pressure of a symmetric electrolyte soap film

In this paper we consider the calculation of the disjoining pressure of a symmetric electrolytic soap film correct to two loops in perturbation theory. We show that the disjoining pressure is finite when the loop expansion is resummed using a cumulant expansion and requires no short distance cutoff in order to give a finite result. The loop expansion is resummed in terms of an expansion in g= lB / lD where lD is the Debye length and lB is the Bjerrum length. We show that there there is a nonanalytic contribution of order g ln(g). We also show that the two-loop correction is greater than the one-loop term at large film thicknesses suggesting a nonperturbative correction to the one-loop result in this limit.

Field theoretic calculation of the surface tension for a model electrolyte system

We carry out the calculation of the surface tension for a model electrolyte to first order in a cumulant expansion about a free-field theory equivalent to the Debye-Hückel approximation. In contrast with previous calculations, the surface tension is calculated directly without recourse to integrating thermodynamic relations. The system considered is a monovalent electrolyte with a region at the interface, of width h, from which the ionic species are excluded. In the case where the external dielectric constant epsilon(0) is smaller than the electrolyte solution's dielectric constant epsilon we show that the calculation at this order can be fully regularized. In the case where h is taken to be zero the Onsager-Samaras limiting law for the excess surface tension of dilute electrolyte solutions is recovered, with corrections coming from a nonzero value of epsilon(0) /epsilon.

Self-diffusion in a system of interacting Langevin particles

The behavior of the self-diffusion constant of Langevin particles interacting via a pairwise interaction is considered. The diffusion constant is calculated approximately within a perturbation theory in the potential strength about the bare diffusion constant. It is shown how this expansion leads to a systematic double expansion in the inverse temperature beta and the particle density rho. The one-loop diagrams in this expansion can be summed exactly and we show that this result is exact in the limit of small beta and rhobeta constants. The one-loop result can also be resummed using a semiphenomenological renormalization group method which has proved useful in the study of diffusion in random media. In certain cases the renormalization group calculation predicts the existence of a diverging relaxation time signaled by the vanishing of the diffusion constant, possible forms of divergence coming from this approximation are discussed. Finally, at a more quantitative level, the results are compared with numerical simulations, in two dimensions, of particles interacting via a soft potential recently used to model the interaction between coiled polymers.

Telecare for patients with type 1 diabetes and inadequate glycemic control: a randomized controlled trial and meta-analysis

OBJECTIVE

To determine the efficacy of telecare (modem transmission of glucometer data and clinician feedback) to support intensive insulin therapy in patients with type 1 diabetes and inadequate glycemic control.

RESEARCH DESIGN AND METHODS

Thirty-one patients with type 1 diabetes on intensive insulin therapy and with HbA1c >7.8% were randomized to telecare (glucometer transmission with feedback) or control (glucometer transmission without feedback) for 6 months. The primary end point was 6-month HbA1c. To place our findings in context, we pooled HbA1c change from baseline reported in randomized trials of telecare identified in a systematic review of the literature.

RESULTS

Compared with the control group, telecare patients had a significantly lower 6-month HbA1c (8.2 vs. 7.8%, P = 0.03, after accounting for HbA1c at baseline) and a nonsignificant fourfold greater chance of achieving 6-month HbA1c < or =7% (29 vs. 7%; risk difference 21.9%, 95% CI -4.7 to 50.5). Nurses spent 50 more min/patient giving feedback on the phone with telecare patients than with control patients. Meta-analysis of seven randomized trials of adult patients with type 1 diabetes found a 0.4% difference (95% CI 0-0.8) in HbA1c mean change from baseline between the telecare and control groups.

CONCLUSIONS

Telecare is associated with small effects on glycemic control in patients with type 1 diabetes on intensive insulin therapy but with inadequate glycemic control.

Field theoretic derivation of the contact value theorem in planar geometries and its modification by the Casimir effect

The contact value theorem for Coulomb gases in planar or filmlike geometries is derived using a Hamiltonian field theoretic representation of the system. The case where the film is enclosed by a material of different dielectric constant to that of the film is shown to contain an additional Casimir-like term which is generated by fluctuations of the electric potential about its mean-field value.

Weak nonlinear surface-charging effects in electrolytic films

A simple model of soap films with nonionic surfactants stabilized by added electrolyte is studied. The model exhibits charge regularization due to the incorporation of a physical mechanism responsible for the formation of a surface charge. We use a Gaussian field theory in the film but the full nonlinear surface terms which are then treated at a one-loop level by calculating the mean-field Poisson-Boltzmann solution and then the fluctuations about this solution. We carefully analyze the renormalization of the theory and apply it to a triple-layer model for a thin film with Stern layer of thickness h. For this model we give expressions for the surface charge sigma(L) and the disjoining pressure P(d)(L) and show their dependence on the parameters. The influence of image charges naturally arises in the formalism, and we show that predictions depend strongly on h because of their effects. In particular, we show that the surface charge vanishes as the film thickness L-->0. The fluctuation terms in this class of theories contribute a Casimir-like attraction across the film. Although this attraction is well known to be negligible compared with the mean-field component for model electrolytic films with no surface-charge regulation, in the model studied here these fluctuations also affect the surface-charge regulation leading to a fluctuation component in the disjoining pressure which has the same behavior as the mean-field component even for large film thickness.

Role of the interaction matrix in mean-field spin glass models

Mean-field models of two-spin Ising spin glasses with interaction matrices taken from ensembles that are invariant under O(N) transformations are studied. A general study shows that the nature of the spin glass transition can be deduced from the eigenvalue spectrum of the interaction matrix. A simple replica approach is derived to carry out the average over the O(N) disorder. The analytic results are confirmed by the extensive Monte Carlo simulations for large system sizes and by the exact enumeration for small system sizes.

Electrostatic fluctuations in soap films

A field theory to describe electrostatic interactions in soap films, described by electric multilayers with a generalized thermodynamic surface-charging mechanism, is studied. In the limit where the electrostatic interactions are weak, this theory is exactly soluble. The theory incorporates in a consistent way, the surface-charging mechanism and the fluctuations in the electrostatic field that correspond to the zero-frequency component of the van der Waals force. It is shown that these terms lead to a Casimir-like attraction that can be sufficiently large to explain the transition between the common black film to a Newton black film.

Steady state behavior of mechanically perturbed spin glasses and ferromagnets

A zero temperature dynamics of Ising spin glasses and ferromagnets on random graphs of finite connectivity is considered. Like granular media, these systems have an extensive entropy of metastable states. We consider the problem of what energy a randomly prepared spin system falls to before becoming stuck in a metastable state. We then introduce a tapping mechanism, analogous to that found in real experiments on granular media. This tapping, corresponding to flipping each spin with probability p simultaneously, leads to a stationary regime with a steady state energy E(p). We explicitly solve this problem for the one-dimensional ferromagnet and the +/-J spin glass, and carry out extensive numerical simulations for spin systems of higher connectivity. In addition our simulations on the ferromagnetic systems reveal a first order transition, whereas the usual thermodynamic transition on these graphs is second order.

Cloning of the mouse sodium iodide symporter

The iodide-concentrating ability of the thyroid gland is essential to the production of thyroid hormone. We report the nucleotide and amino acid sequence of the mouse sodium iodide symporter (mNIS), which mediates this activity within the thyroid gland. An open reading frame of 1,857 nucleotides codes for a protein of 618 amino acids with 95% identity to rat NIS and 84% identity to human NIS. Transient expression of the mNIS cDNA in Chinese hamster ovary (CHO) cells, a nonthyroid cell line, resulted in sodium-dependent, perchlorate-sensitive iodide uptake. Western blot analysis of membrane preparations of CHO cells transiently transfected with mNIS cDNA showed a band of 90 kd when probed with an antibody directed against rat NIS. mNIS will serve as an important reagent in determining the role of NIS in experimental thyroid diseases and for monitoring the immune response to in animal models of NIS-mediated gene therapy.

Extreme-value statistics of hierarchically correlated variables deviation from Gumbel statistics and anomalous persistence

We study analytically the distribution of the minimum of a set of hierarchically correlated random variables E1, E2,ellipsis, E(N) where E(i) represents the energy of the ith path of a directed polymer on a Cayley tree. If the variables were uncorrelated, the minimum energy would have an asymptotic Gumbel distribution. We show that due to the hierarchical correlations, the forward tail of the distribution of the minimum energy becomes highly nonuniversal, depends explicitly on the distribution of the bond energies epsilon, and is generically different from the superexponential forward tail of the Gumbel distribution. The consequence of these results to the persistence of hierarchically correlated random variables is discussed and the persistence is also shown to be generically anomalous.

Tapping spin glasses and ferromagnets on random graphs

We consider a tapping dynamics, analogous to that in experiments on granular media, on spin glasses and ferromagnets on random thin graphs. Between taps, zero temperature single spin flip dynamics takes the system to a metastable state. Tapping corresponds to flipping simultaneously any spin with probability p. This dynamics leads to a stationary regime with a steady state energy E(p). We analytically solve this dynamics for the one-dimensional ferromagnet and +/-J spin glass. Numerical simulations for spin glasses and ferromagnets of higher connectivity are carried out; in particular, we find a novel first order transition for the ferromagnetic systems.

Effect of helicity on the effective diffusivity for incompressible random flows

The advection of a passive scalar by a quenched (frozen) incompressible velocity field is studied by extensive high precision numerical simulation and various approximation schemes. We show that second-order self-consistent perturbation theory, in the absence of helicity, perfectly predicts the effective diffusivity of a tracer particle in such a field. In the presence of helicity in the flow, simulations reveal an unexpectedly strong enhancement of the effective diffusivity which is highly nonperturbative and most visible when the bare molecular diffusivity of the particle is small. We develop and analyze a series of approximation schemes which indicate that this enhancement of the diffusivity is due to a second order effect, whereby the helical component of the field, which does not directly renormalize the effective diffusivity, enhances the strength of the nonhelical part of the flow, which in turn renormalizes the molecular diffusivity. We show that this renormalization is most important at a low bare molecular diffusivity, in agreement with numerical simulations.

Coarsening in the presence of kinetic disorders: analogy to granular compaction

We study the zero temperature dynamics in an Ising chain in the presence of a dynamically induced field that favors locally the " -" phase compared to the " +" phase. At late times, while the " +" domains coarsen as t(1/2), the " -" domains coarsen as t(1/2)log(t). Hence, at late times, the magnetization decays slowly as m(t) = -1+const/log(t). We establish this behavior both analytically within an independent interval approximation and numerically. Our model can be viewed as a simple model for granular compaction, where the system decays into a fully compact state (with all spins " -") in a slow logarithmic manner as seen in recent experiments on granular systems.

Prognostic indicators in differentiated thyroid carcinoma

BACKGROUND

Thyroid cancer ranges from well-differentiated lesions with an excellent prognosis to anaplastic carcinoma, which is almost uniformly fatal. Thus, methods to assess the behavior of thyroid malignancies are necessary to arrive at appropriate treatment decisions.

METHODS

We discuss the factors that affect the prognosis of patients with well-differentiated thyroid malignancies, including papillary, follicular, Hürthle cell, and medullary thyroid carcinomas. We also review the presentation, therapy, and outcome of patients seen at our center over a span of 50 years. These data have identified those prognostic factors that are predictive of survival and recurrence in differentiated thyroid cancer.

RESULTS

Several classifications with different variables have been developed to define risk-group categories. Three widely used systems, in addition to the TNM staging system, include AGES, AMES, and MACIS.

CONCLUSIONS

A better understanding of independently important prognostic variables will result in improved patient care and treatment.

Surface Charging Mechanism and Disjoining Pressure of Electrolytic Soap Films

We present a theory developed to describe the diffuse double layer of electrolytic soap films. The hydrophobic nature of the soap molecules is modeled, in an effective field theory for the system, by the introduction of a free energetic potential favoring the presence of the soap molecules at the film surface. This potential can take various forms, depending on how accurately we wish to model the geometry of the system. The resulting theory is analyzed and leads to the estimation of the electrostatic interactions at the mean field level. A whole range of physical observables is predicted including the electrostatic component of the disjoining pressure isotherm and the Gibbs adsorption isotherm of the system. We compare the theory with accurate disjoining pressure measurements (using X-ray specular reflectivity) carried out on systems composed of sodium dodecyl sulphate (SDS) with two different monovalent electrolytes on a wide range of salinity. The theory appears to account particularly well for the experimental data. A comparison with the DLVO theory is given. Finally, we discuss the limitations of the theory and its modification due to the inclusion of dispersion forces. Copyright 1997 Academic Press. Copyright 1997Academic Press