Clinical Outcomes in Patients with Non-Diagnostic Thyroid Fine Needle Aspiration Cytology: Usefulness of the Thyroid Core Needle Biopsy

Background

Patients with non-diagnostic thyroid fine needle aspiration cytology (FNAC) results undergo repeat FNAC or core needle biopsy (CNB) for definite diagnosis or surgical resection, or are followed up by clinical and ultrasound surveillance. We aimed at evaluating the risk of malignancy in patients with non-diagnostic FNACs and their clinical outcomes according to the follow-up modality.

Methods

We retrospectively reviewed 1,496 (8.8 %) cases with a non-diagnostic result on a first aspiration among 17,045 thyroid FNACs performed between October 2008 and August 2012. Of the non-diagnostic FNACs, 389 patients underwent a second FNAC; 125, CNB; and 89, thyroidectomy by clinical indication. The remaining patients were clinically followed up.

Results

The rate of a second non-diagnostic result was significantly higher on repeat FNAC than on CNB (33.2 vs. 2.4 %; p < 0.001). There was no significant difference in the malignancy risk among patients initially non-diagnostic, twice non-diagnostic, and thrice or more non-diagnostic, nor did this differ from the rate following CNB. No further malignancy was found in cases with ≥2 non-diagnostic CNBs. The malignancy risk was 51 % in those who underwent thyroidectomy. The sensitivity for detecting malignancy was 65 and 70 % for repeat FNACs and first CNBs, respectively, with no false positives seen in either test.

Conclusions

Approximately one-third of repeat FNACs after an initial non-diagnostic aspirate are non-diagnostic on repeat examination, and the malignancy risk may not reduce following repetitively non-diagnostic FNACs. However, a single CNB may be enough to exclude malignancy risk for patients with a non-diagnostic aspirate.     

Na+/H+ Exchanger Regulatory Factor 3 Is Critical for Multidrug Resistance Protein 4–Mediated Drug Efflux in the Kidney

Na⁺/H⁺ exchanger regulatory factor 3 (NHERF3) is a PSD-95/discs large/ZO-1 (PDZ)-based adaptor protein that regulates several membrane-transporting proteins in epithelia. However, the in vivo physiologic role of NHERF3 in transepithelial transport remains poorly understood. Multidrug resistance protein 4 (MRP4) is an ATP binding cassette transporter that mediates the efflux of organic molecules, such as nucleoside analogs, in the gastrointestinal and renal epithelia. Here, we report that Nherf3 knockout (Nherf3^−/−) mice exhibit profound reductions in Mrp4 expression and Mrp4-mediated drug transport in the kidney. A search for the binding partners of the COOH-terminal PDZ binding motif of MRP4 among several epithelial PDZ proteins indicated that MRP4 associated most strongly with NHERF3. When expressed in HEK293 cells, NHERF3 increased membrane expression of MRP4 by reducing internalization of cell surface MRP4 and consequently, augmented MRP4-mediated efflux of adefovir, a nucleoside-based antiviral agent and well known substrate of MRP4. Examination of wild-type and Nherf3^−/− mice revealed that Nherf3 is most abundantly expressed in the kidney and has a prominent role in modulating Mrp4 levels. Deletion of Nherf3 in mice caused a profound reduction in Mrp4 expression at the apical membrane of renal proximal tubules and evoked a significant increase in the plasma and kidney concentrations of adefovir, with a corresponding decrease in the systemic clearance of this drug. These results suggest that NHERF3 is a key regulator of organic transport in the kidney, particularly MRP4-mediated clearance of drug molecules.Assembly of protein complexes by adaptor proteins with PSD-95/discs large/ZO-1 (PDZ) domains plays an important role in the regulation of many membrane proteins, especially in epithelial and neuronal tissues.^1,2 For example, PDZ-based adapter proteins in epithelia, such as Shank2, synaptic scaffolding molecule (S-SCAM), and Na⁺/H⁺ exchanger regulatory factors (NHERFs), are known to be involved in the regulation of cell surface expression and the activity of many membrane transporters and receptors in the respiratory, digestive, urinary, and reproductive organs.^3–6 The four members of the NHERF proteins (NHERF1 to 4) contain either two or four PDZ domains and were the first family of PDZ-containing proteins shown to be involved in epithelial transport. NHERF3, also known as PDZK1 or CAP70, has four PDZ domains and is normally localized to the apical microdomains of gastrointestinal and kidney epithelia. Each PDZ domain of NHERF3 has been proposed to bind independently to the PDZ binding motif of various membrane proteins, such as the cystic fibrosis transmembrane conductance regulator (CFTR), the Na⁺/H⁺ exchanger 3, the urate transporter, and the organic anion transporter 4.^7–10 However, Nherf3 knockout (Nherf3^−/−) mice do not have a discernible phenotype except mild hypercholesterolemia,¹¹ and, consequently, the in vivo role of NHERF3 in transepithelial transport remains poorly understood.Transporters belonging to either the ATP binding cassette (ABC) or the solute-linked carrier superfamilies of membrane proteins play diverse roles in the pharmacokinetic and pharmacodynamic pathways of drugs and their metabolites.¹² Multidrug resistance protein 4 (MRP4/ABCC4) is a member of the C subfamily of ABC transporters and mediates the efflux of a group of organic molecules using energy generated from the binding and hydrolysis of ATP.¹³ Cumulative evidence suggests that MRP4 pumps out purine compounds and plays an important role in the renal elimination of purine-based antiviral and antineoplastic agents.^14,15 However, the regulatory mechanisms for MRP4 expression and function have not been extensively studied.The COOH terminus of MRP4 contains a class 1 PDZ interaction motif (-S/T-X-Ф, where Ф is a hydrophobic amino acid),¹⁶ indicating that MRP4 may interact with PDZ-based adaptors in epithelia. In preliminary studies using a yeast two-hybrid assay, MRP4 was found to strongly interact with NHERF3 among several PDZ adaptor proteins expressed in epithelial tissues. The aim of the present study was to identify the physiologic and pharmacologic roles of the interaction of NHERF3 with MRP4 using a variety of in vitro and in vivo experimental approaches. The results obtained provide strong evidence that NHERF3 is a key regulator of organic transport in the kidney, particularly the MRP4-mediated clearance of purine-based drug molecules.     

The Difference in Comorbidities and Behavioral Aspects between Internet Abuse and Internet Dependence in Korean Male Adolescents

Objective

This study examined the differences in psychiatric comorbidities and behavioral aspects in accordance with the severity of Internet addiction in male adolescents.

Methods

One hundred and twenty-five adolescents from four middle and high schools in Seoul were enrolled in this study. The subjects were divided into non-addict, abuse, and dependence groups according to a diagnostic interview by psychiatrists. The psychiatric comorbidities and behavioral aspects of subjects were evaluated through psychiatric clinical interviews based on the Diagnostic and Statistical Manual of Mental Disorders (4th edition), the Children''s Depression Inventory, the State-Trait Anxiety Inventory, the Internet Addiction Test, and a self-reported questionnaire about behavioral aspects.

Results

The psychiatric comorbidity distributions were significantly different in the abuse and dependence groups, particularly in terms of attention-deficit hyperactivity disorder and mood disorder items. The Children''s Depression Inventory, the State-Trait Anxiety Inventory, and the Internet Addiction Test scores were also significantly different among the three groups. There were significant differences in 10 of the 20 items of the Internet Addiction Test between the non-addict, abuse, and dependence groups. There were significant differences in seven items between the non-addict and abuse groups, but no differences between subjects in the abuse and dependence groups. Significant differences were observed in three items between the abuse and dependence groups, but there were no significant differences between the non-addict and abuse groups. In terms of behavioral aspects, scores for abusive, sexual, and decreased social interest behaviors were highest in the dependence group, and lowest in the non-addict group. However, the behavioral aspects of decreased interpersonal relationships did not show this difference between groups.

Conclusion

This study suggests that there are differences in psychiatric comorbidities and behavioral aspects between adolescent males with characteristics of Internet abuse and Internet dependence.     

Delay in the Recovery of Normal Sleep-Wake Cycle after Disruption of the Light-Dark Cycle in Mice: A Bipolar Disorder-Prone Animal Model?

Objective

Disruption of the circadian rhythm is known as a provoking factor for manic episodes. Individual differences exist in the recovery rate from disruption in the general population. To develop a screening method to detect individuals vulnerable to bipolar disorder, the authors observed the relationship between the recovery of the normal sleep-wake cycle after switching the light-dark (LD) cycle and quinpirole-induced hyperactivity in mice.

Methods

Sixteen male mice (age of 5 weeks, weight 28-29 gm) were subjected to a circadian rhythm disruption protocol. Sleep-wake behaviors were checked every 5 min for a total duration of 15 days, i.e., 2 days of baseline observations, 3 days of LD cycle changes, and 10 days of recovery. During the dark cycle on the 16th experimental day, their general locomotor activities were measured in an open field for 120 minutes after an injection of quinpirole (0.5 mg/kg, s.c.).

Results

The individual differences in the recovery rate of the baseline sleep-wake cycle were noted after 3 days of switching the LD cycle. Fifty percent (n=8) of the mice returned to the baseline cycle within 6 days after normalizing the LD cycle (early recovery group). The locomotor activities of mice that failed to recover within 6 days (delayed recovery group) were significantly higher (mean rank=12.25) than those of the early recovery group (mean rank=4.75, u=62.0, p=0.001, Mann-Whitney U test).

Conclusion

Given that the quinpirole-induced hyperactivity is an animal model of bipolar disorder, our results suggest individuals who have difficulties in recovery from circadian rhythm disruption may be vulnerable to bipolar disorder.