Subclinical thyroid dysfunction and chronic kidney disease: a nationwide population-based study

BACKGROUND

Chronic kidney disease (CKD) has a significant impact on global health. Studies have shown that subclinical thyroid dysfunction may be related to CKD, but the association between subclinical thyroid dysfunction and CKD in the general population is unclear. We aimed to evaluate the risk of CKD according to thyroid function status in a large cohort.

METHODS

We analyzed data from a nationwide, population-based, cross-sectional survey (KNHANES VI). A total of 3,257 participants aged ≥ 19 years who underwent thyroid and kidney function assessments were included in this study. CKD was defined as an estimated glomerular filtration rate < 60 mL/min/1.73 m2 and/or urine albumin-creatinine ratio ≥ 30 mg/g. The risk of CKD according to thyroid function status was assessed using logistic regression, adjusted for potential confounders.

RESULTS

Overall, 6.7% of the participants had CKD. There were no significant differences in thyroid-stimulating hormone and free thyroxine levels between the groups with and without CKD. The proportion of participants with CKD was significantly different among the thyroid function status groups (p = 0.012) and tended to increase significantly in the following order: subclinical hyperthyroidism (1.5%), euthyroidism (6.6%), and subclinical hypothyroidism (12.6%) (p for trend < 0.001). Subclinical hypothyroidism was a significant risk factor for CKD, even after adjusting for sex, age, household income, education, smoking, alcohol consumption, walking activity, abdominal obesity, hypertension, low high-density lipoprotein cholesterol, elevated triglycerides, hyperglycemia, free thyroxine, and thyroid-peroxidase anibody (odds ratio 2.161, 95% confidence interval 1.032-4.527, p = 0.041).

CONCLUSION

Subclinical hypothyroidism is an independent predictor of CKD in the general population.

Risk of carotid plaques according to triglyceride-glucose index stratified by thyroid function: A cross-sectional study

BACKGROUND

Recent studies have indicated that the triglyceride-glucose (TyG) index or subclinical thyroid dysfunction is associated with carotid plaques, a predictor of cardiovascular disease risk. However, evidence for this association is limited and inconsistent. This study aimed to evaluate the risk of carotid plaques according to TyG index and thyroid function status in the general population.

METHODS

A total of 2,931 individuals who underwent carotid ultrasound as part of a comprehensive health examination at the Health Promotion Center of Soonchunhyang University Hospital were retrospectively reviewed. Based on the TyG index and thyroid function status, the participants were divided into six groups: LoTyG-SHyper (low TyG index with subclinical hyperthyroidism), LoTyG-Eu (low TyG index with euthyroidism), LoTyG-SHypo (low TyG index with subclinical hypothyroidism), HiTyG-SHyper (high TyG index with subclinical hyperthyroidism), HiTyG-Eu (high TyG index with euthyroidism), and HiTyG-SHypo (high TyG index with subclinical hypothyroidism). A multivariate logistic regression analysis was conducted to determine the risk of carotid plaques.

RESULTS

The proportion of participants with significant carotid plaques was significantly different among the six groups (p<0.001, p for trend<0.001). The odds ratio (OR) and 95% confidence interval (CI) for significant carotid plaques were significantly higher in the HiTyG-SHypo group than in the LoTyG-Eu group, even after adjusting for confounding variables including sex, age, smoking, obesity, hypertension and diabetes mellitus (OR 1.506, 95% CI 1.045-2.170, p = 0.028). The OR of significant carotid plaques was higher in the HiTyG-Eu group than in the LoTyG-Eu group; however no associations were observed after additional adjustment for confounding variables.

CONCLUSION

The TyG index and thyroid function status are important predictors of the risk of carotid plaques in healthy individuals. Early evaluation of carotid plaques may be necessary for subjects with high insulin resistance and subclinical hypothyroidism.

Association between iodine intake and metabolic syndrome in euthyroid adult in an iodine-replete area: a nationwide population-based study

Metabolic syndrome (MetS) is considered very important because of the increased risk for cardiovascular diseases. Identifying modifiable factors may help prevent MetS. We aimed to investigate the relationship between iodine intake as a dietary factor and MetS in euthyroid adult in an iodine-replete area. A total of 4,277 adult aged ≥19 years from the Korea National Health and Nutrition Examination Survey VI (2013-2015) with urinary iodine concentration (UIC) results and normal thyroid function were included. Participants were grouped according to their iodine nutrition status based on the WHO recommendations and modifications: insufficient (<100 μg/L), adequate (100-299 μg/L), and excessive (≥300 μg/L) iodine intake. We estimated the odds ratios (ORs) for MetS according to the UIC groups using logistic regression models. Of the study participants, 27.2% men and 23.9% women had MetS. Men with excessive iodine intake had a significantly lower risk of elevated triglycerides [OR 0.733, 95% confidence interval (CI) 0.603-0.890, p = 0.010], as compared to those with adequate iodine intake. Women with insufficient iodine intake had a significantly greater risk of elevated blood glucose (OR 1.519, 95% CI 1.011-2.282, p = 0.044), as compared to those with adequate iodine intake. In women, insufficient iodine intake was a significant risk factor for MetS compared to adequate iodine intake, even after adjusting for confounding variables including age, smoking, alcohol consumption, walking activity, serum thyroid-stimulating hormone, free thyroxine, and anti-thyroid peroxidase antibody (OR 1.544, 95% CI 1.031-2.311, p = 0.035). There was no association between iodine intake and risk of MetS in men. In conclusion, insufficient iodine intake was associated with an increased risk of MetS only in euthyroid adult women. Our data support that sex differences may influence the relationship between iodine intake as a dietary pattern and MetS.

Association of thyroid autoimmunity with nonalcoholic fatty liver disease in euthyroid middle-aged subjects: A population-based study

BACKGROUND AND AIM

The association between thyroid autoimmunity and nonalcoholic fatty liver disease (NAFLD) remains unclear. In this study, we aimed to investigate the relationship between thyroid autoimmunity and NAFLD in a large cohort of euthyroid subjects.

METHODS

We analyzed clinical and biochemical data from a nationwide, population-based, cross-sectional survey (KNHANES VI). A total of 1589 middle-aged participants aged 45-65 years, with normal thyroid function, were included in this study. NAFLD was defined as a hepatic steatosis index of > 36. We estimated the odds ratios (ORs) for NAFLD according to anti-thyroid peroxidase antibody (TPOAb) positivity by using logistic regression models, and adjusted for potential confounders.

RESULTS

Overall, 24% (n = 378) of the subjects had NAFLD. Subjects with NAFLD showed a higher positivity for TPOAb (11% vs 7%, P = 0.014) compared with those without NAFLD. TPOAb positivity was a significant risk factor for NAFLD [OR 1.668, 95% confidence interval (CI) 1.019-2.730, P = 0.042] even after adjusting for confounding variables, including age, sex, household income, education, smoking, alcohol consumption, walking activity, abdominal obesity, elevated blood pressure, dyslipidemia and hyperglycemia. In addition, TPOAb positivity predicted the risk of advanced liver fibrosis (OR 3.112, 95% CI 1.256-7.713, P = 0.014) in subjects with NAFLD, independent of the confounding variables.

CONCLUSION

In euthyroid subjects, thyroid autoimmunity is associated with NAFLD and advanced liver fibrosis, independent of known metabolic risk factors. Large longitudinal studies in the future will help clarify the causality.

Association of free thyroxine with obstructive lung pattern in euthyroid middle-aged subjects: A population-based study

Background

The association between thyroid hormone levels and pulmonary function in euthyroid population is still unclear. We aimed to examine the relationship between thyroid function and lung function in a large cohort study of euthyroid subjects.

Methods

We analyzed biochemical and spirometry data from a nationwide, population-based, cross-sectional survey (KNHANES VI). A total of 1,261 middle-aged participants aged 45–65 years with spirometry tests and normal thyroid function were included in this study. The subjects were grouped according to free thyroxine (fT4) (ng/dL) quartiles (Q1, 0.89–1.09; Q2, 1.10–1.19; Q3, 1.20–1.30; Q4, 1.31–1.76). Obstructive lung pattern was defined as forced expiratory volume in one second (FEV₁)/forced vital capacity (FVC) <0.7. The probability of obstructive lung patterns according to fT4 quartiles was assessed using logistic regression models, adjusted for potential confounders.

Results

Overall, 10.9% of the subjects had an obstructive lung pattern. The mean fT4 levels were significantly higher in those with obstructive lung pattern than in those with normal lung function (1.26 vs. 1.20 ng/dL, p<0.001). The proportion of participants with obstructive lung pattern increased across the fT4 quartile categories (p<0.001). With the Q1 group as reference, the multivariate-adjusted odds ratios (95% confidence intervals) for obstructive lung pattern in the Q3 and Q4 groups were 2.875 (1.265–6.535) and 2.970 (1.287–6.854), respectively, even after adjusting for confounding variables.

Conclusion

High fT4 levels are an independent predictor of obstructive lung pattern in euthyroid middle-aged subjects. Further prospective studies are needed to confirm these findings.

Efficacy of Differential Diagnosis of Thyroid Nodules by Shear Wave Elastography-the Stiffness Map

BACKGROUND

Fine needle aspiration is the gold standard for differential diagnosis of thyroid nodules; however, the malignancy rate for indeterminate cytology is 20% to 50%.

OBJECTIVE

We evaluated the efficacy of shear wave elastography added to ultrasonography for differential diagnosis of thyroid nodules.

METHODS

We retrospectively reviewed the medical records of 258 consecutive patients. Thyroid nodules were divided into 4 categories according to maximum elasticity (EMax) and nodule depth/width (D/W) ratio: Category 1 (EMax ≥ 42.6 kPa; D/W < 0.9); Category 2 (EMax < 42.6 kPa; D/W < 0.9); Category 3 (EMax ≥ 42.6 kPa; D/W ≥ 0.9); and Category 4 (EMax < 42.6 kPa; D/W ≥ 0.9). The EMax cutoff value was set using receiver operating characteristic (ROC) curve analysis to predict nodular hyperplasia (NH) vs follicular neoplasm (FN). Cutoff value for nodule D/W ratio was set using ROC curve analysis for malignancy.

RESULTS

NH was the most prevalent pathology group in Category 1, FN in Category 2, and papillary thyroid carcinoma in Category 3. Category 3 demonstrated the highest rate of malignancy (81.8%) and had 55.4% sensitivity and 90% specificity for predicting malignancy. When assessing the benign pathology of NH in follicular patterned lesion, Category 1 demonstrated the highest NH prevalence of 88.9% (34/37) and had 73.9% sensitivity and 85.0% specificity.

CONCLUSION

The performance for malignancy was highest in Category 3 and predictive ability for benign pathology of NH in follicular lesion was highest in Category 1. The information of EMax and nodule D/W ratio was useful to predict the pathology of thyroid nodules.

Thyroid autoimmunity and metabolic syndrome: a nationwide population-based study

OBJECTIVE

Recent studies have reported that thyroid hormone levels are associated with metabolic syndrome (MetS) even in euthyroid subjects. However, the association between thyroid autoimmunity and MetS is uncertain. This study aimed to investigate the relationship between thyroid autoimmunity and MetS in a large cohort study of euthyroid subjects.

METHODS

A total of 4775 participants aged ≥19 years from the Korea National Health and Nutrition Examination Survey VI (2013-2015) with anti-thyroid peroxidase antibody (TPOAb) results and normal thyroid functions were included in this study. Subjects were grouped according to thyroid autoimmunity (positivity of TPOAb). We estimated the odds ratios (ORs) for MetS according to TPOAb positivity using logistic regression models, adjusted for potential confounders.

RESULTS

Of the study subjects, 25% (n = 1206) were diagnosed with MetS. Subjects with MetS showed higher median TPOAb levels (6.3 vs 6.8 IU/mL, P < 0.001) and higher positivity of TPOAb (5 vs 7%, P = 0.002) than those without MetS. There was a significant difference in prevalence of MetS depending on the TPOAb positivity (25% vs 33%, P = 0.002). Subjects with TPOAb positive had a significantly greater risk of abdominal obesity (OR 1.675, 95% CI: 1.302-2.154, P < 0.001), low high-density lipoprotein cholesterol (OR: 1.603, 95% CI: 1.244-2.066, P < 0.001) and elevated blood pressure (OR: 1.418, 95% CI: 1.099-1.829, P = 0.007) as compared to those with TPOAb negative. Positivity of TPOAb was a significant risk factor for MetS even after adjusting for confounding variables including age, sex, household income, education, smoking, alcohol consumption, walking activity, thyroid-stimulating hormone and free thyroxine (OR: 1.389, 95% CI: 1.048-1.841, P = 0.022).

CONCLUSION

In euthyroid subjects, thyroid autoimmunity is associated with MetS. Further large longitudinal studies are needed to clarify causality.

Efficacy of Differential Diagnosis of Thyroid Nodules by Shear Wave Elastography, the Stiffness Map

Background: Fine-needle aspiration (FNA) is the first step in the differential diagnosis of thyroid nodules. However, malignancy rate of the indeterminate FNA is reported as 20-50 %. We aimed to evaluate the efficacy of shear wave elastography (SWE), the map of stiffness in the differential diagnosis of the histopathology of thyroid nodules. Methods: We retrospectively reviewed the medical records of 258 consecutive patients who visited the thyroid clinic for thyroid nodules and who underwent SWE before ultrasound-guided FNA and/or core-needle biopsy. We analyzed the EI using the total nodular region of interest method by the Q-Box Trace program. Thyroid nodules were divided in to 4 categoies according to maximum elasticity (E_Max) and nodule depth/width (D/W) ratio; Category 1 (E_Max ≥42.6 kPa & D/W<0.9), Category 2 (E_Max <42.6 kPa & D/W<0.9), Category 3 (E_Max ≥42.6 kPa & D/W≥ 0.9) and Category 4 (E_Max<46.2 kPa & D/W≥ 0.9). The cutoff value of E_Max was set using ROC curve analysis to predict follicular neoplasm (FN) from nodular hyperplasia (NH). Cutoff value ​​for nodule D/W ratio was set using ROC curve analysis to differentiate malignant nodule. Results: FN showed the lowest E_Max among all pathologies and lower E_Max than NH (p<0.05). FN was distributed mostly in the category 2 (70%) and NH was distributed mainly in the category 1 (73.9%). CLT belonged mostly to the category 1 (57.1%). PTC belonged in majority to the category 3 (58.9%) and the rest.to the category 1 (25%). So NH was the most frequent pathology group in category 1.FN was the most frequent pathology group in the category 2 and PTC was the most frequent pathology group in the category 3. Conclusion: SWE showed characteristic patterns of various pathology groups reflecting the degree of fibrosis and the information of E_Max and nodule depth/width (D/W) ratio determining the category was useful to predict the pathology of thyroid nodules along with the advantage of noninvasiveness.

Shear wave elasticity by tracing total nodule showed high reproducibility and concordance with fibrosis in thyroid cancer

Background

Although shear wave elastography (SWE) is reported to be useful in detecting malignant thyroid nodules, it shows a wide range of cut-off values of elasticity index (EI) in detecting malignant nodules. The cause of discrepancy remains unclear. Fibrosis of the tumors is known to increase the EI in SWE, and matching of SWE and surgical histopathology has not been fully illustrated in thyroid cancer. We aimed to evaluate the reproducibility of the new total nodular region of interest (ROI) method excluding the subjective features of focal circular ROI placement and to determine the lesion that causes the elevation of EI on SWE and on histopathology.

Methods

A total of 29 thyroid cancers from 28 patients were included. We evaluated the reproducibility of EI in the new total nodular ROI using Q-Box Trace program and compared the EI in focal nodular ROI using a 3-mm circular area. We analyzed the correlation between fibrosis and EI.

Result

The coefficient of variation (CV) of the intrarater assay was significantly lower in total nodular ROI than in focal nodular ROI within the image in rater 1 (1.7% vs. 13.4%, p < 0.001) and in rater 2 (1.4% vs. 16.9%, p < 0.001) and in different images in rater 1 (7.6% vs. 12.3%, p = 0.040) and in rater 2 (7.5% vs. 19.8%, p = 0.004). Moreover, CV of the interrater assay showed similar results (14.9% vs. 19%, p = 0.030). Interrater intraclass correlation coefficient showed better agreement in total nodular ROI than in focal nodular ROI (0.863 vs. 0.783). The degree of fibrosis on histopathology showed significant correlations with EI (E_Mean, p < 0.001; E_Max, p = 0.027), and the location of fibrosis was concordant with the high EI area on SWE.

Conclusion

Our study revealed that the new total nodular ROI method showed higher reproducibility and better agreement in intra- and interrater assay than the focal nodular ROI method, suggesting a valuable and standardized method in clinical practice. Moreover, our results showed that fibrosis in the histopathology increased EI on SWE and might lead to the discrepancy of the cut-off values in detecting thyroid cancer.

Utility of shear wave elastography to detect papillary thyroid carcinoma in thyroid nodules: efficacy of the standard deviation elasticity

BACKGROUND/AIMS

The aim of this study was to address the role of the elasticity index as a possible predictive marker for detecting papillary thyroid carcinoma (PTC) and quantitatively assess shear wave elastography (SWE) as a tool for differentiating PTC from benign thyroid nodules.

METHODS

One hundred and nineteen patients with thyroid nodules undergoing SWE before ultrasound-guided fine needle aspiration and core needle biopsy were analyzed. The mean (EMean), minimum (EMin), maximum (EMax), and standard deviation (ESD) of SWE elasticity indices were measured.

RESULTS

Among 105 nodules, 14 were PTC and 91 were benign. The EMean, EMin, and EMax values were significantly higher in PTCs than benign nodules (EMean 37.4 in PTC vs. 23.7 in benign nodules, p = 0.005; EMin 27.9 vs. 17.8, p = 0.034; EMax 46.7 vs. 31.5, p < 0.001). The EMean, EMin, and EMax were significantly associated with PTC with diagnostic odds ratios varying from 6.74 to 9.91, high specificities (86.4%, 86.4%, and 88.1%, respectively), and positive likelihood ratios (4.21, 3.69, and 4.82, respectively). The ESD values were significantly higher in PTC than in benign nodules (6.3 vs. 2.6, p < 0.001). ESD had the highest specificity (96.6%) when applied with a cut-off value of 6.5 kPa. It had a positive likelihood ratio of 14.75 and a diagnostic odds ratio of 28.50.

CONCLUSION

The shear elasticity index of ESD, with higher likelihood ratios for PTC, will probably identify nodules that have a high potential for malignancy. It may help to identify and select malignant nodules, while reducing unnecessary fine needle aspiration and core needle biopsies of benign nodules.

Association between Serum Cystatin C and Vascular Complications in Type 2 Diabetes Mellitus without Nephropathy

BACKGROUND

Recent studies have correlated serum cystatin C (CysC) with vascular complications, but few studies have investigated this correlation in diabetes patients without nephropathy. This study aimed to evaluate if higher serum CysC levels increase the risk for vascular complications in type 2 diabetes mellitus patients with normal renal function or mild renal impairment.

METHODS

A total of 806 consecutive patients with type 2 diabetes mellitus who were admitted to the diabetes center of Soonchunhyang University Hospital for blood glucose control were retrospectively reviewed. Patients with nephropathy were excluded. Subjects were categorized into quartiles of serum CysC levels (Q1, ≤0.65 mg/L; Q2, 0.66 to 0.79 mg/L; Q3, 0.80 to 0.94 mg/L; and Q4, ≥0.95 mg/L).

RESULTS

The proportion of patients with diabetic retinopathy (DR) (P for trend <0.001), coronary heart disease (CHD) (P for trend <0.001), and stroke (P for trend <0.001) increased across the serum CysC quartiles. After adjustment for confounding factors, the highest serum CysC level remained a significant risk factor for DR (odds ratio [OR], 1.929; 95% confidence interval [CI], 1.007 to 4.144; P=0.040). Compared with Q1, a significant positive association was observed between serum CysC and CHD in Q2 (OR, 7.321; 95% CI, 1.114 to 48.114; P=0.012), Q3 (OR, 6.027; 95% CI, 0.952 to 38.161; P=0.020), and Q4 (OR, 8.122; 95% CI, 1.258 to 52.453; P=0.007). No associations were observed between CysC and stroke after additional adjustment for confounding variables.

CONCLUSION

Serum CysC levels are independently associated with DR and CHD, suggesting that CysC may be useful for identifying type 2 diabetes mellitus patients without nephropathy who are at high risk for vascular complications.

Association between Sarcopenia, Sarcopenic Obesity, and Chronic Disease in Korean Elderly

Background

It is a very important social issue for Korea to have a healthy old age as an aged society. Aging causes a lot of physical changes, especially sarcopenia. Sarcopenia is defined as a persistent decrease in skeletal muscle and muscle strength. Sarcopenic obesity is a phenomenon in which fat is replaced instead of muscle. The purpose of this study was to examine the prevalence of sarcopenia and sarcopenic obesity in Korean elderly and to analyze the relationship with chronic disease.

Methods

Data from the 2008 to 2011 the Korea National Health and Nutrition Survey were used. A total of 3,492 patients were classified into 3 groups (non-sarcopenia, sarcopenia, sarcopenic obesity), and general, anthropometry, health behavior, nutrient intake and chronic disease status were compared by the statistical analysis.

Results

The rate of moderate exercise was significantly lower in the sarcopenia and sarcopenic-obesity group than in the non-sarcopenia group (P=0.007). The sarcopenic obesity group had significantly higher energy (P=0.005), protein (P=0.046) and fat (P=0.001) intake than the sarcopenic group. The sarcopenic-obesity group had the highest ratio of diabetes (P=0.023) and dyslipidemia (P=0.004) in the 3 groups. Compared with the non-sarcopenia group, in the sarcopenia and sarcopenic obesity groups, the odds ratios (ORs) of diabetes was increased by 1.24 and 2.16 while the ORs of dyslipidemia was increased by 1.12 and 1.50, respectively.

Conclusions

Regular exercise and adequate nutrient intake (energy, protein and fat) are essential for the prevention of sarcopenia in Korean elderly, and management of chronic disease in sarcopenic obesity elderly is important.

Efficacy of Shear-Wave Elastography for Detecting Postoperative Cervical Lymph Node Metastasis in Papillary Thyroid Carcinoma

AIMS

To evaluate shear-wave elastography (SWE) as a tool to detect postoperative cervical lymph node (LN) metastasis in patients with papillary thyroid carcinoma (PTC).

METHODS

Forty-three LNs of 43 patients with PTC undergoing ultrasound (US) and SWE before ultrasound-guided fine-needle aspiration (FNA) for the evaluation of postoperative cervical LN recurrences were analyzed. The mean (E_Mean), minimum (E_Min), maximum (E_Max), and standard deviation (E_SD) of SWE elasticity indices were measured.

RESULTS

Among 43 indeterminate or suspicious LNs, 12 were malignant and 31 were benign. The E_Mean, E_Min, E_Max, and E_SD values were significantly higher in malignant LNs than in benign LNs (E_Mean: 37.1 kPa in malignant versus 11.8 kPa in benign LNs, P < 0.001; E_Min: 11.3 kPa versus 5.1 kPa, P = 0.046; E_Max: 50.5 kPa versus 23.7 kPa, P < 0.001; and E_SD: 7.8 kPa versus 4.1 kPa, P = 0.006). E_Max had the highest accuracy (93.0%) when applied with a cut-off value of 37.5 kPa. It had a positive likelihood ratio of 25.83 and a diagnostic odds ratio of 150.0.

CONCLUSIONS

The shear elasticity index of E_Max, with higher likelihood ratios for malignant LNs, may help identify postoperative cervical LN metastasis in PTC patients with indeterminate or suspicious LNs.

Case report of a bilateral adrenal myelolipoma associated with Cushing disease

RATIONALE

Adrenal myelolipomas are rare benign tumors, composed of a variable mixture of mature adipose tissue and hematopoietic tissue. These tumors are frequently detected incidentally and are usually asymptomatic, and hormonally inactive.

PATIENT CONCERNS

During a routine health checkup, a 52-year-old man was found to have a tumor on the bilateral adrenal glands. Abdominal computed tomography revealed a well-defined, heterogeneously enhanced bilateral adrenal mass, suggesting a myelolipoma.

DIAGNOSES

The hormonal evaluation revealed adrenocorticotropic hormone (ACTH) dependent Cushing syndrome.

INTERVENTIONS

The patient underwent left adrenalectomy, and transsphenoidal resection of a pituitary mass. The final diagnosis was adrenal myelolipoma associated with Cushing disease.

OUTCOMES

Growth of right adrenal myelolipoma was detected during the 7-year follow-up. There were enhancing pituitary lesions in repeat magnetic resonance imaging of the sellar region, which implies persistent or recurrent pituitary adenoma. This case reinforces relationship between Cushing disease and adrenal myelolipoma.

LESSONS

To the best of our knowledge, this is the first reported pathologically confirmed bilateral adrenal myelolipoma associated with Cushing disease. This report supports the idea that ACTH is associated with the development of adrenal myelolipoma.

Preoperative serum thyroglobulin and changes in serum thyroglobulin during TSH suppression independently predict follicular thyroid carcinoma in thyroid nodules with a cytological diagnosis of follicular lesion

BACKGROUND

Fine-needle aspiration biopsy (FNAB) cannot distinguish a follicular thyroid carcinoma (FTC) from a follicular adenoma in follicular lesions. We designed this study to determine whether the preoperative thyroglobulin (Tg) and change in serum Tg during thyroid-stimulating hormone (TSH) suppression can predict FTC in thyroid nodules with a cytological diagnosis of follicular lesion.

METHODS

Among 854 patients who underwent thyroid surgery, the 198 patients who presented with thyroid nodules with a cytological diagnosis of follicular lesion were analyzed. Predictive factors for malignancy were evaluated using multivariate logistic regression models. Subgroup analyses of patients with TSH suppression therapy by levothyroxine were also conducted.

RESULTS

Thirty-two patients (16%) had FTC, and 166 patients had confirmed benign nodules. The median preoperative serum Tg levels were significantly higher in patients with FTC compared to those with benign pathology (449 vs. 34 ng/mL, p < 0.001). The serum Tg (odds ratios (OR) 10.311, p < 0.001) and tumor volume (OR 4.500, p = 0.035) were found to be independent predictors for FTC in all patients with a cytological diagnosis of follicular lesion. Forty-eight patients received TSH suppression therapy. When we performed subgroup analyses on the patients with TSH suppression therapy, decrease less than 15% in serum Tg during TSH suppression was found to be an independent predictor of FTC (OR 13.918, p = 0.018).

CONCLUSION

Preoperative serum Tg and changes in serum Tg during TSH suppression independently predict FTC in thyroid nodules with a cytological diagnosis of follicular lesion.

Association of triiodothyronine levels with future development of metabolic syndrome in euthyroid middle-aged subjects: a 6-year retrospective longitudinal study

BACKGROUND

Several cross-sectional studies have reported that thyroid hormone levels are associated with cardiovascular risk markers and metabolic syndrome (MetS) even in euthyroid subjects. However, the prognostic role of serum thyroid hormone levels in the risk of incident MetS has not been elucidated.

AIM

We aimed to investigate the associations of baseline serum thyroid hormone levels with the development of MetS in healthy subjects.

METHODS

This 6-year, cross-sectional, longitudinal and follow-up study was conducted in 12 037 euthyroid middle-aged subjects without MetS subjected to comprehensive health examinations. Subjects were grouped according to total triiodothyronine (T3) quartiles. The hazard ratio (HR) for the development of MetS according to T3 quartiles was estimated using Cox proportional hazards model.

RESULTS

During the 6-year period, 3544 incident cases of MetS (29%) were identified. The proportion of subjects with incident MetS increased across the T3 quartiles (P for trend <0.001). The HR and 95% confidence interval (CI) for the development of MetS were significantly higher in the highest T3 quartile compared with the lowest T3 quartile even after adjusting for confounding variables including gender, age and smoking (HR: 1.238, 95% CI: 1.128-1.358, P < 0.001).

CONCLUSION

In euthyroid middle-aged subjects, serum T3 levels are associated with increased risk for future development of MetS.

Prognostic Value of Labyrinthine 3D-FLAIR Abnormalities in Idiopathic Sudden Sensorineural Hearing Loss

BACKGROUND AND PURPOSE

According to recent research, modern MR imaging can detect the presense of abnormalities on labyrinthine. Our aim was to report the patterns and prognostic role of abnormal findings on labyrinthine imaging in patients with sudden sensorineural hearing loss.

MATERIALS AND METHODS

This study comprised 113 patients who were diagnosed with unilateral sudden sensorineural hearing loss and underwent 3T MR imaging, including pre-/postcontrast 3D fluid-attenuated inversion recovery and T1-weighted imaging. We analyzed abnormalities on MR imaging and correlated them with audiometric results.

RESULTS

Thirty-one (27%) patients showed abnormal findings on labyrinthine MR imaging in the affected ear. The initial/final hearing levels of the MRI+ group (91 ± 25/73 ± 27 dB hearing loss) were significantly worse than those of the MRI- group (69 ± 30/48 ± 24 dB hearing loss). The incidence of abnormalities on labyrinthine MR imaging was significantly lower (3 of 40, 8%) in 40 patients with initial mild-to-moderate hearing loss than in those with profound hearing loss (16 of 34, 47%). Considering hearing improvement by the Siegel criteria, the rate of complete or partial recovery was significantly higher in the MRI- group (34%) than in the MRI+ group (10%). In patients with initial severe or profound hearing loss, the MRI- group showed greater hearing improvement (38 ± 21 dB) than the MRI+ group (23 ± 22 dB).

CONCLUSIONS

Abnormalities on labyrinthine MR imaging were found in 27% of patients with sudden sensorineural hearing loss. The initial hearing loss was worse in the MRI+ group than in the MRI- group. In patients with initial severe and profound hearing loss, the presence of abnormalities on labyrinthine MR imaging indicated a poor prognosis.

Triiodothyronine Levels Are Independently Associated with Metabolic Syndrome in Euthyroid Middle-Aged Subjects

BACKGROUND

Recent studies have shown an association between thyroid hormone levels and metabolic syndrome (MetS) among euthyroid individuals; however, there have been some inconsistencies between studies. Here, we evaluated the relationship between thyroid hormone levels and MetS in euthyroid middle-aged subjects in a large cohort.

METHODS

A retrospective analysis of 13,496 euthyroid middle-aged subjects who participated in comprehensive health examinations was performed. Subjects were grouped according to thyroid stimulating hormone, total triiodothyronine (T3), total thyroxine (T4), and T3-to-T4 ratio quartile categories. We estimated the odds ratios (ORs) for MetS according to thyroid hormone quartiles using logistic regression models, adjusted for potential confounders.

RESULTS

Of the study patients, 12% (n=1,664) had MetS. A higher T3 level and T3-to-T4 ratio were associated with unfavourable metabolic profiles, such as higher body mass index, systolic and diastolic blood pressure, triglycerides, fasting glucose and glycated hemoglobin, and lower high density lipoprotein cholesterol levels. The proportion of participants with MetS increased across the T3 quartile categories (P for trend <0.001) and the T3-to-T4 ratio quartile categories (P for trend <0.001). The multi-variate-adjusted OR (95% confidence interval) for MetS in the highest T3 quartile group was 1.249 (1.020 to 1.529) compared to the lowest T3 quartile group, and that in the highest T3-to-T4 ratio quartile group was 1.458 (1.141 to 1.863) compared to the lowest T3-to-T4 ratio quartile group, even after adjustment for potential confounders.

CONCLUSION

Serum T3 levels and T3-to-T4 ratio are independently associated with MetS in euthyroid middle-aged subjects. Longitudinal studies are needed to define this association and its potential health implications.

Quantitative analysis of gains and catch-up saccades of video-head-impulse testing by age in normal subjects

OBJECTIVES

To evaluate video-head-impulse test (vHIT) results in normal subjects, to determine the normative values of vHIT for the vestibulo-ocular reflex (VOR) and to characterise the catch-up saccades (CSs).

DESIGN

Prospective cohort study.

SETTING

Tertiary care academic referral centre.

PARTICIPANTS

Fifty healthy subjects with no history of vestibular impairment, ten each in their 20's, 30's, 40's, 50's and 60's, underwent vHITs in the lateral semicircular canal plane.

MAIN OUTCOME MEASURES

vHIT gains and the incidence and amplitudes of covert and overt CSs.

RESULTS

The mean vHIT gain was 1.02 ± 0.07, and the mean gain asymmetry was 2.39 ± 1.96%, with no significant differences among age groups. CSs were observed during 22.6% of the trials and in 49% of the ears. The incidence of CSs was not associated with age. The mean velocity of CSs was 55.5 ± 16.9°/s, and its mean interaural difference was 11.8 ± 10.7°/s.

CONCLUSIONS

vHIT gains were consistently equal to 1.0 in all age groups (20's to 60's), suggesting that abnormal criteria for vHIT gain (e.g. 0.8) and gain asymmetry (e.g. 8%) can be used, regardless of age. CSs were observed in about half of normal ears, suggesting that VOR is a hypometric system. The amplitudes and interaural difference of CSs were also similar in all age groups, suggesting that abnormal criteria for CS amplitude (e.g. 100°/s) and interaural difference (e.g. 40°/s) can be used, regardless of age.

Vertical components of head-shaking nystagmus in vestibular neuritis, Meniere's disease and migrainous vertigo

OBJECTIVES

To describe vertical and horizontal components of head-shaking nystagmus (HSN) in various vestibular disorders.

DESIGN

Retrospective case review.

SETTING

Tertiary care academic referral centre.

PARTICIPANTS

Head-shaking nystagmus was assessed in 66 vestibular neuritis (VN) patients at acute (<7 days) and follow-up (2 months), and 65 Meniere's disease (MD) and 76 migrainous vertigo (MV) in interictal period.

MAIN OUTCOME MEASURES

Head-shaking nystagmus was categorised as pure horizontal, pure vertical or mixed. Horizontal HSN was classified as monophasic or biphasic and paretic or recovery. Vertical HSN was classified as upbeat or downbeat.

RESULTS

Abnormal HSN (pathologic monophasic, biphasic or delayed-peak HSN) showed different positive rates depending on the vestibular disorders and compensation (94% in acute VN; 89% in FU VN; 78% in MD; 50% in MV). Paretic HSN with the nystagmus towards the lesioned side was the most common type in VN and MD; however, recovery HSN with the nystagmus towards the intact side could be rarely observed especially in patients with MD or compensated VN. Vertical nystagmus could be combined with horizontal HSN, and upbeat HSN was observed in most (83%) of the patients with acute VN, but downbeat HSN was common in follow-up VN (83%), MD (97%) and MV (85%). Weak perverted HSN, which is assumed to be a central nystagmus, was rarely observed in MD and MV (6-9%), but not in VN.

CONCLUSIONS

Head-shaking nystagmus (HSN) in horizontal plane is a valuable tool in the assessment of vestibular imbalance. Common observation of upbeat HSN in acute VN and downbeat HSN in follow-up VN, MD and MV suggests that vertical components are possibly related to the involvement of vestibular apparatus and compensation. Weak perverted HSN and delayed-peak HSN were rarely observed in MD and MV, and never observed in VN, suggesting that it is possibly related to either asymmetrically impaired vertical canals or misorientation of the velocity-storage system.

Relationship between Decrease in Serum Sodium Level and Bone Mineral Density in Osteoporotic Fracture Patients

Background

Recently, it has been suggested that decrease in serum sodium level is associated with osteoporosis. However, no study in Korea has reported the association of decrease in serum sodium level with osteoporosis. In this study, we investigated the relationship between the decrease in serum sodium level and severity of osteoporotic fracture in patients.

Methods

We enrolled 290 subjects who were admitted and operated at Soonchunhyang University Hospital due to major fractures. For the control group, we enrolled 1,027 subjects who visited a health promotion center. We carried a 1:1 matching with age and sex from the case group.

Results

In a total of 164 age- and sex-matched subjects, serum sodium level was significantly lower in the fracture group than in the non-fracture group (P=0.001). Serum sodium level was significantly lower in the severe osteoporosis group than that in the non-severe osteoporosis group (P=0.002). Old age and decrease in serum sodium level were independent risk factors of osteoporosis (odds ratio [OR]=1.088, P=0.008, confidence interval [CI]=[1.022-1.157]; OR= 0.840, P=0.037, CI=0.713-0.989).

Conclusions

Serum sodium level was significantly lower in the fracture group than that in the non-fracture group and in the severe osteoporosis group than that in the non-severe osteoporosis group. Based on our results, the decrease in serum sodium level could be an independent risk factor for osteoporosis.

Number of tumor foci as predictor of lateral lymph node metastasis in papillary thyroid carcinoma

BACKGROUND

The purpose of this study was to determine the clinicopathologic characteristics of patients with papillary thyroid carcinoma (PTC) by the number of tumor foci.

METHODS

A retrospective analysis of 2095 patients with PTC was performed. The study population was divided into 4 groups based on the number of tumor foci: N1 (1 tumor focus), N2 (2 foci), N3 (3 foci), and N4 (4 or more foci).

RESULTS

An increasing number of tumor foci was significantly associated with older age at diagnosis (p = .006), cervical lymph node metastasis (p < .001), and advanced TNM stage of disease (p = .001) at initial surgery. The multivariate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for the N2, N3, and N4 groups compared to the N1 group for lateral lymph node metastasis were OR 1.53 (95% CI, 1.05-2.22), OR 2.57 (95% CI, 1.50-4.42), and OR 2.88 (95% CI, 1.42-5.84), respectively.

CONCLUSION

An increase in the number of tumor foci was strongly associated with older age at diagnosis, cervical lymph node metastasis, and advanced TNM stage of PTC. The number of tumor foci independently predicted lateral lymph node metastasis.

Endoscopic comparison of alendronate alone and the enteric-coated alendronate with calcitriol combination in postmenopausal Korean females

BACKGROUND/AIMS

This study was performed to compare the mucosal findings after esophagogastroduodenoscopy in two groups before and after the use of alendronate only and following administration of the enteric-coated alendronate (5 mg) and calcitriol (0.5 µg) combined drug (Maxmarvil, Yuyu Co.).

METHODS

The study population consisted of 33 postmenopausal healthy female volunteers, aged 50 to 70 years (mean age, 58 ± 5) without gastrointestinal symptoms and with normal baseline endoscopic findings. Esophagogastroduodenoscopy was performed at baseline and was repeated 2 weeks later after daily intake of Maxmarvil (n = 17 subjects) or alendronate only (n = 16 subjects). Mucosal injury scores were reported by an endoscopist after 2 weeks of treatment with each medication schedule.

RESULTS

Esophageal mucosal injuries developed in two of 16 subjects in the alendronate only group and 0 of 17 in the Maxmarvil group. Gastric mucosal injuries developed in eight subjects in the alendronate group and four subjects in the Maxmarvil group; this difference was statistically significant.

CONCLUSIONS

The mucosal damage scores for the alendronate group (total score 24) were significantly higher than those for the Maxmarvil group (total score 9) in the esophagus and stomach. Therefore, this study suggested that enteric-coated Maxmarvil is less harmful to gastrointestinal mucosa than alendronate, and may improve the tolerability of osteoporosis medication in clinical practice.

DNA methylation of RUNX3 in papillary thyroid cancer

BACKGROUND/AIMS

The relationship between Runt-related transcription factor 3 (RUNX3) gene inactivation and various solid tumors has been reported; however, little information is available about RUNX3 in thyroid cancers.

METHODS

We evaluated the DNA methylation of RUNX3 in 13 papillary thyroid cancer tissues and four thyroid cancer cell lines. Additionally, using reverse transcriptase-polymerase chain reaction, we analyzed RUNX3 gene expression in several thyroid cancer cell lines after treating with the demethylating agent 5-aza-2'-deoxycytidine (DAC).

RESULTS

RUNX3 was hypermethylated in many thyroid cancer cell lines and in 10 of the 12 papillary thyroid cancer tissues. Treatment with DAC increased the expression of RUNX3 in some thyroid cancer cell lines.

CONCLUSIONS

We suggest that RUNX3 is associated with thyroid carcinogenesis, and RUNX3 methylation is a potentially useful diagnostic marker for papillary thyroid cancer.

Coenzyme Q10 in combination with steroid therapy for treatment of sudden sensorineural hearing loss: a controlled prospective study

OBJECTIVE

To evaluate the therapeutic efficacy of coenzyme Q10 added to systemic steroid in patients with idiopathic sudden sensorineural hearing loss.

DESIGN

A controlled prospective study.

SETTING

Asan medical center, University of Ulsan College of Medicine.

PARTICIPANTS

Between August 2007 and October 2008, the first 60 patients diagnosed with sudden sensorineural hearing loss were managed with systemic steroid treatment for 2 weeks including 5-day hospitalisation. And the second 60 patients were managed with coenzyme Q10 for 2 weeks added to previous management.

MAIN OUTCOME MEASURES

We evaluated auditory function by pure tone audiometry and speech discrimination score. Auditory evaluations were performed before and 3 months after treatment using Siegel's criteria. The degree of improvement in four-tone average hearing and speech discrimination score was calculated from the results before and after treatment.

RESULTS

The total hearing improvement rate after the treatment was 75.0% (90/120 patients) in this study. Although 47 patients (78.3%) of coenzyme Q10 group showed better hearing improvement than 43 patients (71.7%) of control group, there was no significant difference. However, the coenzyme Q10 group showed significantly higher improvement in speech discrimination score.

CONCLUSION

From this study, we suggest that coenzyme Q10 may have beneficial effects in the treatment of sudden sensorineural hearing loss.

Endoscopic transnasal reduction of an anterior table frontal sinus fracture: technical note

Repair of an isolated anterior table frontal sinus fracture traditionally requires a coronal incision, which results in a large scar, alopecia and paresthesias, because of these problems, endoscopic approaches have been attempted. These approaches still involve small incisions at the forehead or behind the hairline so might be better described as endoscopy-assisted surgery. This report describes the reduction of an isolated anterior table frontal sinus fracture in a 14-year-old boy using an endoscopic procedure that involves a transnasal approach with no external incisions. Endoscopic instruments were used under 25 and 70 degrees endoscope guidance. A custom-made latex glove balloon was inserted into the frontal sinus, and then expanded and maintained for 20 days to support the reduced bony fragments. Postoperatively, the reduction was successful. The cosmetic deformity was repaired and there was no postoperative morbidity. This case indicates that endoscopic reduction may be a valuable treatment option for certain types of frontal sinus fractures.

Mutation of Glu78 of the AVP-NPII gene impairs neurophysin as a carrier protein for arginine vasopressin in a family with neurohypophyseal diabetes insipidus

Familial neurohypophyseal diabetes insipidus (FNDI; OMIM 192340) is a rare inherited disorder with an autosomal dominant inheritance pattern. It is characterized by persistent polydipsia and polyuria induced by deficient or absent secretion of arginine vasopressin (AVP). We report a Korean kindred in whom FNDI is associated with a novel deletion mutation in exon 2 of the AVP-NPII gene encoding the neurophysin II moiety. An 18-yr-old man with polyuria and polydipsia was shown to have central diabetes insipidus by using the water deprivation test. Four family members were suspected to have symptomatic vasopressin-deficient diabetes insipidus. Direct sequencing of the AVP-NPII gene showed a heterozygous GAG deletion mutation in exon 2, which results in in-frame deletion of glutamic acid (c.232_234delGAG; p.Glu78del). The mutation was predicted to yield an abnormal AVP precursor lacking Glu78 (E78) in its neurophysin II moiety. Because Glu78 is essential for neurophysin II molecules to form a salt bridge with AVP, the function of neurophysin as a carrier protein for AVP would be impaired. The proband's mother and sister have the same mutation. Presence of this mutation suggests that the portion of the neurophysin peptide encoded by this sequence is important for the appropriate expression of vasopressin.

Increased expression of focal adhesion kinase in thyroid cancer: immunohistochemical study

Focal adhesion kinase (FAK) is a tyrosine kinase that is found in cellular structures called focal adhesions. FAK appears to be a key element in signal transduction pathways involved in cell adhesion and locomotion. FAK is overexpressed in various tumors, including tumors derived from regions of the head and neck, colon, breast, prostate, and liver. In this study, we investigated immunohistochemically whether FAK expression was increased in thyroid cancers. FAK staining was not seen in any of the 20 normal thyroid tissues or the 6 nodular hyperplasia specimens. In contrast, FAK staining was observed in all of 17 papillary carcinomas, 9 follicular carcinomas, 8 medullary carcinomas, and 2 anaplastic carcinomas. Nine of 17 follicular adenomas showed FAK immunoreactivity. FAK was not expressed in normal tissue and nodular hyperplasia, but was expressed in some of the follicular adenoma, and all of the follicular, papillary, medullary and anaplastic thyroid carcinoma. This result indicates that the up-regulation of FAK may play a role in the development of thyroid carcinogenesis.

Immunohistochemical expression of COX-2 in thyroid nodules

BACKGROUND

Recent evidence indicates that elevated COX-2 expression is associated with the carcinogenesis of numerous neoplasms. In this study, we investigated COX-2 expression in various thyroid specimens in order to elucidate its physiological role in pathologic conditions, and to evaluate the efficiency of COX-2 protein expression as a molecular marker of malignancy in the thyroid gland.

METHODS

COX-2 expression was studied immunohistochemically in 19 papillary carcinomas, 8 follicular carcinomas, 14 follicular adenomas, 2 Hürthle cell carcinomas, 4 Hürthle cell adenomas, 8 nodular hyperplasias, 3 Graves' diseases, 3 Hashimoto's thyroiditis, 2 medullary carcinomas, 1 anaplastic carcinoma, and 20 normal thyroid tissues.

RESULTS

COX-2 staining was not seen in any of the normal thyroid, Graves' disease, or nodular hyperplasia specimens. In contrast, COX-2 staining was observed in all of papillary carcinomas, Hashimoto's thyroiditis, Hürthle cell carcinomas, and Hürthle cell adenomas tissues. Moreover, 7 of 8 follicular carcinomas and 11 of 14 follicular adenomas showed COX-2 staining.

CONCLUSION

These results indicate that COX-2 is not useful as a marker of malignancy. Since COX-2 expression was evident in follicular adenomas and in papillary and follicular carcinomas. Thus, the enzyme may be involved in the early process of thyroid tumorigenesis.

Implication of the small GTPase Rac1 in the apoptosis induced by UV in Rat-2 fibroblasts

Exposure of mammalian cells to ultraviolet (UV) light elicits a cellular response and also lead to apoptotic cell death. However, the role of Rac, a member of Rho family GTPases, in the UV-induced apoptosis has never been examined. In UV-irradiated Rat-2 fibroblasts, nuclear fragmentation began to be observed within 2 h and the total viability of Rat-2 cells were only about 15% at 6 h following by UV irradiation, whereas the total viability in Rat2-Rac(N17) cells stably expressing RacN17, a dominant negative Rac1 mutant, was almost close to 67%. Pretreatment with SB203580, a specific inhibitor of p38 kinase, likewise attenuated UV-induced cell death, but PD98059, a MEK inhibitor, did not. Thus, Rac1 and p38 kinase appear to be components in the apoptotic signaling pathway induced by UV irradiation in Rat-2 fibroblasts. In addition, our results show that p38 kinase stimulation by UV is dramatically inhibited by RacN17, suggesting that p38 kinase is situated downstream of Rac1 in the UV signaling to apoptosis.

Role of the cytosolic phospholipase A2-linked cascade in signaling by an oncogenic, constitutively active Ha-Ras isoform

Activation of Ras signaling by growth factors has been associated with gene regulation and cell proliferation. Here we characterize the contributory role of cytosolic phospholipase A(2) in the oncogenic Ha-Ras(V12) signaling pathway leading to activation of c-fos serum response element (SRE) and transformation in Rat-2 fibroblasts. Using a c-fos SRE-luciferase reporter gene, we showed that the transactivation of SRE by Ha-Ras(V12) is mainly via a Rac-linked cascade, although the Raf-mitogen-activated protein kinase cascade is required for full activation. In addition, Ha-Ras(V12)-induced DNA synthesis was significantly attenuated by microinjection of recombinant Rac(N17), a dominant negative mutant of Rac1. To identify the mediators downstream of Rac in the Ha-Ras(V12) signaling, we investigated the involvement of cytosolic phospholipase A(2). Oncogenic Ha-Ras(V12)-induced SRE activation was significantly inhibited by either pretreatment with mepacrine, a phospholipase A(2) inhibitor, or cotransfection with the antisense oligonucleotide of cytosolic phospholipase A(2). We also found cytosolic phospholipase A(2) to be situated downstream of Ha-Ras(V12) in a signal pathway leading to transformation. Together, these results are indicative of mediatory roles of Rac and cytosolic phospholipase A(2) in the signaling pathway by which Ha-Ras(V12) transactivates c-fos SRE and transformation. Our findings point to cytosolic phospholipase A(2) as a novel potential target for suppressing oncogenic Ha-Ras(V12) signaling in the cell.

Codon 54 polymorphism of the fatty acid binding protein 2 gene is associated with increased fat oxidation and hyperinsulinemia, but not with intestinal fatty acid absorption in Korean men

The alanine to threonine substitution at codon 54 (Ala54Thr) of the fatty acid binding protein 2 (FABP2) gene has been reported to be associated with increased fat oxidation and insulin resistance in several populations. It has been hypothesized that Ala54Thr substitution results in enhanced intestinal uptake of fatty acids and thereby an impairment of insulin action, but this hypothesis has not been proven in vivo. We studied the association between the Ala54Thr polymorphism of the FABP2 gene and intestinal (3)H-oleic acid absorption, as well as basal insulin level, basal metabolic rate, and fat oxidation rate in 96 healthy young Korean men. Among our subjects, the allele frequency of the Ala54Thr substitution was 0.34. Subjects with Thr54-encoding allele were found to have a higher mean fasting plasma insulin concentration and a higher basal fat oxidation rate compared with the subjects who were homozygous for the Ala54-encoding allele. However, there was no significant difference in basal metabolic rate or (3)H-oleic acid absorption according to the FABP2 gene polymorphism. These results suggest that the Ala54Thr substitution in the FABP2 gene is associated with increased fat oxidation and hyperinsulinemia in normal Korean men, but these effects are not mediated by an increase in the intestinal fatty acid absorption.

Tumor necrosis factor-alpha generates reactive oxygen species via a cytosolic phospholipase A2-linked cascade

Reactive oxygen species (ROS) are important regulatory molecules implicated in the signaling cascade triggered by tumor necrosis factor (TNF)-alpha, although the events through which TNF-alpha induces ROS generation are not yet well characterized. We therefore investigated selected candidates likely to mediate TNF-alpha-induced ROS generation. Consistent with the role of Rac in that process, stable expression of Rac(Asn-17), a dominant negative Rac1 mutant, completely blocked TNF-alpha-induced ROS generation. To understand better the mediators downstream of Rac, we investigated the involvement of cytosolic phospholipase A(2) (cPLA(2)) activation and metabolism of the resultant arachidonic acid (AA) by 5-lipoxygenase (5-LO). TNF-alpha-induced ROS generation was blocked by inhibition of cPLA(2) or 5-LO, but not cyclooxygenase, suggesting that TNF-alpha-induced ROS generation is dependent on synthesis of AA and its subsequent metabolism to leukotrienes. Consistent with that hypothesis, TNF-alpha Rac-dependently stimulated endogenous production of leukotriene B(4) (LTB(4)), while exogenous application of LTB(4) increased levels of ROS. In contrast, application of leukotrienes C(4), D(4), and E(4) or prostaglandin E(2) had little effect. Our findings suggest that LTB(4) production by 5-LO is situated downstream of the Rac-cPLA(2) cascade, and we conclude that Rac, cPLA(2), and LTB(4) play pivotal roles in the ROS-generating cascade triggered by TNF-alpha.

Role of cytosolic phospholipase A(2) as a downstream mediator of Rac in the signaling pathway to JNK stimulation

Rac is an important regulatory molecule implicated in c-jun N-terminal kinase (JNK) activation in response to stress and cytokines. However, the signaling events that mediate the activation of JNK by Rac are not yet well characterized. To broaden our understanding of downstream mediators that link Rac signals to the JNK pathway, we investigated whether cytosolic phospholipase A(2) (cPLA(2)) is involved in Rac activation of JNK. In this report we demonstrate that either co-transfection with antisense cPLA(2) oligonucleotide or pretreatment with arachidonyltrifluoromethyl ketone (AACOCF3), a potent and specific inhibitor of cPLA(2), inhibits Rac-mediated JNK activation, implying a potential role of cPLA(2) in Rac-signaling to JNK activation. In accordance with this observation, we demonstrate that the addition of exogenous arachidonic acid (AA), a principal product of Rac-activated cPLA(2), or leukotrienes, products of 5-lipoxygenase (5-LO) of AA, caused a specific stimulation of JNK. Together, our findings suggest that cPLA(2) mediates, at least partly, the signaling cascade by which Rac stimulates JNK.

Spatiotemporal Dynamics of Attention-Induced Distortions and Illusions

Selective attention induces perceptual distortions, ranging from repulsion of objects located near the attended area (Suzuki and Cavanagh, 1994 Investigative Ophthalmology and Visual Science35 2081) to magnification of inattended objects (Tsal and Shalev, 1996 Journal of Experimental Psychology: Human Perception and Performance22 233 – 243). Two hypothetical mechanisms have been postulated: a shift of receptive field positions away from the locus of attention (receptive-field shift hypothesis) or the enlargement of perceived space around the attended location (spatial-enlargement hypothesis). The aim of the present study was to distinguish between these two hypotheses, by investigating the spatial and temporal properties of attention-induced distortions.

Perceptual judgments on Vernier alignment, line tilt, line length, and size of outlined figures were used to measure attention-induced changes in perception. Attention was induced exogenously (by blinking a specific set of dots around the test stimuli) or endogenously (by instructing the subject to selectively attend the dots). After inducing attention, the test stimuli were briefly flashed. A staircase method was used to measure the attentional effect. The experiment was performed with 3 Korean and 3 German subjects.

A vertical line was perceived as repelled from the locus of attention, and a line segment appeared longer when attention was given to its vicinity. In addition, several well-known illusions (eg the Ponzo and the Gibson illusions) were produced by having the subjects merely attend a set of inducing dots. The effects decreased as the distance between the locus of attention or the time between the onset of attention and the stimulus presentation increased. The results imply that the space-enlargement hypothesis provides a better explanation for the attention-induced changes in perception than the receptive-field-shift hypothesis.

The Arabidopsis thaliana plasma membrane H(+)-ATPase multigene family. Genomic sequence and expression of a third isoform

The plasma membrane of higher plants contains a H(+)-ATPase as its major ion pump. This enzyme belongs to the P-type family of cation-translocating enzymes and generates the proton-motive force that drives solute uptake across the plasma membrane. In Arabidopsis thaliana the plasma membrane H(+)-ATPase is encoded by a multigene family (Harper, J. F., Surowy, T. K., and Sussman, M. R. (1989) Proc. Natl. Acad. Sci. U. S. A. 86, 1234-1238). The complete genomic sequence of a third Arabidopsis H(+)-ATPase isoform (referred to as AHA2) is presented here, and the predicted protein sequence is compared with previously published AHA1, AHA3, and tobacco Nicotiana plumbaginifolia NP1 isoforms. The AHA2 gene is most similar to AHA1, with predicted proteins containing 95% amino acid identity. The mRNA start site and 5'-untranslated sequence for AHA2 were determined from cDNA amplified by the polymerase chain reaction. The 5' region contains a 23-base pair (bp) polypyrimidine sequence and a short upstream reading frame. In comparison with the 16 introns reported in AHA3, AHA2 is missing one intron in the 5'-untranslated region and a second intron in the C-terminal coding region. An unusually large intron for Arabidopsis (greater than 1000 bp) is present at the beginning of the coding sequence of both AHA2 and AHA3. In the 3'-untranslated sequence of AHA1 and AHA2 but not AHA3, there is a 65-bp region of 85% identity and a second shorter region of 16-bp identity harboring an unusual putative poly(A) addition signal (dTTTGAAGAAACAAGGC). Northern blot analysis indicates that AHA2 mRNA relative to total cellular RNA is expressed at significantly higher levels in root tissue as compared with shoot tissue.