The incidence of early colorectal epithelial neoplasm (ECEN) is increasing, and its pathologic diagnosis is important for patient care. We investigated the incidence of ECEN and the current status of its pathologic diagnosis.
We collected datasheets from 25 institutes in Korea for the incidence of colorectal adenoma with high grade dysplasia (HGD) and low grade dysplasia in years 2005, 2007, and 2009; and early colorectal carcinoma in the year 2009. We also surveyed the diagnostic terminology of ECEN currently used by the participating pathologists.
The average percentage of diagnoses of adenoma HGD was 7.0%, 5.0%, and 3.4% in years 2005, 2007, and 2009, respectively. The range of incidence rates of adenoma HGD across the participating institutes has gradually narrowed over the years 2005 to 2009. The incidence rate of early colorectal carcinoma in the year 2009 was 21.2%. The participants did not share a single criterion or terminology for the diagnosis of adenoma HGD. The majority accepted the diagnostic terms that distinguished noninvasive, mucosal confined, and submucosal invasive carcinoma.
Further research requirements suggested are a diagnostic consensus for the histopathologic diagnosis of ECEN; and standardization of diagnostic terminology critical for determining the disease code.
Colorectal neoplasms; Pathology, surgical; Multicenter study; Incidence; Diagnosis
Ultrasonographic (US) criteria on malignant thyroid bed mass have been suggested, including taller than wide shape, loss of echogenic hilum, abnormal vascularity, and microcalcification. The relationship between fine-needle aspiration (FNA) cytology findings and US findings on thyroid bed mass is unknown. We have retrospectively assessed the malignant thyroid bed mass after total thyroidectomy due to papillary thyroid carcinoma (PTC).
We retrospectively evaluated 2,048 patients who underwent total thyroidectomy due to PTC. FNA was performed in 97 patients on the thyroid bed under US surveillance. The 97 suspicious thyroid bed masses were divided into two groups: metastatic thyroid bed group (n = 34) and nonmetastatic group (n = 63). The groups were evaluated according to various clinical, serologic, and US findings.
Within a median 47.0 months of follow-up, the proportion of malignant thyroid bed mass was high in large tumor size (1.37 cm vs. 1.03 cm), isthmic position (10.3% vs. 3.9%), and previous N1a (55.9% vs. 34.9%). US findings revealed that the presence of microcalcification or macrocalcification (47.1% vs. 19.0%) and thyroid bed mass height (5.4 mm vs. 3.9 mm) were the only discriminable criteria for central compartment recurrence. But, degree of echogenicity, loss of hilum, and irregularity of margin failed to discriminate malignant thyroid bed mass.
US findings on malignant thyroid bed mass were different from previously reported general criteria on lateral metastatic nodes. Additional FNA cytology should be performed on patients, even low-risk patients, who present the above findings.
Ultrasonography; Fine-needle biopsy; Thyroidectomy; Papillary thyroid cancer
The aim of this study was to evaluate the effect of polishing and glazing on the color and spectral distribution of monolithic zirconia.
MATERIALS AND METHODS
Forty-five monolithic zirconia specimens (16.3 mm × 16.4 mm × 2.0 mm) were fabricated and divided into 5 groups according to the number of A2-coloring liquid applications (Group I to V). Each group was divided into 3 subgroups according to the method of surface treatments (n=3): N: no treatment; P: polishing; G: glazing. Color and spectral distribution of five different areas of each specimen were measured according to CIELAB color space in the reflectance mode relative to the standard illuminant D65 on a reflection spectrophotometer. Data were analyzed using one-way ANOVA followed by Tukey's HSD test, Pearson correlation and regression analysis (α=.05).
There was a significant difference in CIE L* between Subgroup N and P, and in CIE b* between Subgroup P and G in each group. Spectral reflectance generally decreased in Subgroup P and G in comparison with Subgroup N. Color differences between Subgroup P and G were within the perceptibility threshold (ΔE*ab< 3.7) in most groups. Highly significant correlation was found between CIE b*and each subgroups as the number of coloring liquid applications increased (R2>0.88, P<.001).
A perceptible color difference can be detected after polishing of monolithic zirconia. Polishing decreases the lightness, and glazing also decreases the lightness, but increases the yellowness of monolithic zirconia.
Zirconia-based ceramic; Color; Dental polishing; Surface properties
The pathogenesis of bone loss in patients with inflammatory bowel disease (IBD) is complex, multifactorial, and only partly understood. We aimed to examine the extent and risk factors of bone mass reduction and to analyze the impact of early onset of a disease before attaining peak bone mass in IBD patients.
We compared the risk factors for osteoporosis and BMD at the lumbar spine and the hip bone in IBD patients.
A total of 44 patients with IBD were enrolled. Twenty-one and 23 patients were diagnosed as IBD before and after the age of 30 and designated as group A and group B, respectively. Group A had significant bone mass reduction at the lumbar spine than group B (BMD, 1.01±0.10 vs. 1.14±0.17, p<0.01; T-score, -1.22±0.84 vs. -0.08±1.39, p<0.01; Z-score, -1.11±0.81 vs. -0.03±1.32, p<0.01, respectively). Multivariate analysis showed that patients diagnosed as IBD before the age of 30 had possible risk factor of bone mass reduction (hazard ratio, 3.96; p=0.06).
Bone mass reduction was more severe in patients who were diagnosed with IBD before the age of 30 than in those diagnosed after the age of 30.
Inflammatory bowel diseases; Bone density; Steroids; Age
We investigated the prognosis according to age in papillary thyroid carcinoma (PTC) patients.
We retrospectively evaluated 2,890 patients who underwent thyroidectomy due to PTC between May 2004 and Aug 2008. We divided patients into 3 groups: young (≤35 years old), middle (between 35 and 54 years old), and old (≥55 years old).
Median age was 47.0 years old (range, 15 to 82 years). Within a follow-up period median of 50 months, there were 148 (5.1%) locoregional recurrences, 6 (0.2%) PTC-related deaths, and 18 (0.6%) PTC-unrelated deaths. Outcomes were more favorable in the young group, with no PTC-related death despite the frequent locoregional recurrence. In the old group compared to the middle, there was a higher proportion of male, and more aggressive types as T3 or N1b, higher mean tumor number, more multiplicity, and bilaterality. The old group of ≥55 years did not show a significant difference in PTC-related deaths than other age groups in Cox analysis (OR, 0.9; P = 0.677), but a significant cutoff age in PTC-related deaths at 62.5 years was determined in ROC analysis (area under curve = 0.912).
We showed that the ≤35 years group shows favorable prognosis despite the frequent locoregional recurrence and ≥62.5 years group shows a poor prognosis regardless of other factors such as male sex or tumor aggressiveness. Further multiinstitutional studies are needed to elucidate the prognosis according to patient's age.
Age; Prognosis; Papillary thyroid carcinoma
Hypereosinophilic syndrome (HES) has three defining features: marked hypereosinophilia for at least 6 months, no confirmed etiology for the eosinophilia, and eosinophilia-related symptoms or organ dysfunction. However, a shorter period of hypereosinophilia with symptoms requiring eosinophil-lowering therapy is also acceptable. We report a case of HES presenting as eosinophilic colitis. Although hypereosinophilia was present for 3 months, this patient needed to be treated with eosionphil-lowering therapy for severe hematochezia. After systemic corticosteroid therapy, symptoms caused by organ involvement were dramatically improved.
Hypereosinophilic syndrome; Colon; Steroids
There are no guidelines for the optimal timing of the decision of when to perform completion thyroidectomy, and controversy exists regarding how the timing of completion thyroidectomy impacts survival patterns. We investigated the legitimacy of an observational strategy in central node metastasis after thyroid lobectomy for papillary thyroid cancer (PTC).
We retrospectively evaluated 522 consecutive patients who underwent thyroid lobectomy. Of the 69 patients with central metastasis, 61 patients (88.4%) were included in an observational study under cautious evaluation with informed consent by the patients, and compared with an observation arm of 180 postlobectomy N0 (node negative proven) patients.
Of the 522 patients, six (1.1%) thyroid, five (0.9%) central, and two (0.4%) lateral recurrences were observed. Lateral recurrences occurred in the immediate completion N0 and Nx groups but not in the N1a observation arms. There were two (3.3%) central recurrences without thyroid or lateral recurrence on the observation arm of N1a observation patients. But two (1.1%) thyroid and three (1.7%) central recurrences were on the observation arm of N0 patients. In Kaplan-Meier survival curves for central or lateral recurrences between observation arms for the N1a and N0 groups, no significant difference was found between the N1a and N0 observation arms (P = 0.365).
The timing of when to perform completion thyroidectomy in central metastases-proven patients after lobectomy for PTC should be based on the patient's risk category.
Observation; Lymphatic metastasis; Thyroid neoplasms; Thyroidectomy
Enteropathy-type T-cell lymphoma (ETL) or enteropathy-associated T-cell lymphoma is a very rare malignant intestinal tumor. ETL is usually diagnosed by surgery. Endoscopic findings of ETL are not well known, and there are few reports of findings from endoscopy that has been performed only using white light. Additionally, there are no definite treatment guidelines for ETL. Therefore, we report a case of ETL diagnosed by enteroscopy with imaging-enhanced endoscopy and also review recently developed treatment options.
Enteropathy-type T-cell lymphoma; Imaging enhanced endoscopy; Narrow band image
Parathyroid neoplasms; Parathyroid cancer, adult; Hypercalcemia
Hyperplastic polyposis syndrome (HPS) is a rare condition characterized by the presence of numerous hyperplastic polyps (HPs) in the colon and rectum. Patients with HPS have an increased risk of colorectal cancer. This link is associated with gene mutations, especially B type Raf kinase (BRAF). However, a case of HPS associated with gene mutations has seldom been reported in Korea. Here, we describe a case of HPS in which a BRAF mutation was present in a 34-year-old woman. She had more than 110 HPs in the stomach and colorectum, which we removed. All of the polyps were diagnosed histologically as HPs, and no adenomatous or malignant changes were noted. We performed a BRAF and K-ras mutation analysis as well as a microsatellite analysis on the resected colon polyps. BRAF mutations were found in the resected colon polyps, but there was no evidence of K-RAS mutation or microsatellite instability.
Hyperplastic polyposis syndrome; BRAF
We investigated the incidence and risk factors of hypothyroidism after thyroid lobectomy, and evaluated the possibility to predict hypothyroidism preoperatively with serologic markers, such as thyrotropin (TSH), thyroglobulin (TG), anti-thyroglobulin (ATA), and anti-microsomal antibody (AMA).
We enrolled 123 consecutive patients who underwent thyroid lobectomy due to benign conditions between May 2004 and April 2008. Only preoperative euthyroid patients were included. Patients were divided into two groups by postoperative thyroid function outcomes, into hypothyroid (n = 97) and euthyroid groups (n = 26), and analyzed specially for the preoperative levels of TSH, TG, ATA, and AMA.
Twenty-six (21.1%) patients developed hypothyroidism following thyroid lobectomy within 35.7 months of follow-up. The proportion of post-lobectomy hypothyroidism was high in patients with high-normal preoperative TSH level, and the cut-off value was 2.0 mIU/L, with 67% sensitivity and 75% specificity. The quantitative titer of preoperative TG, ATA, and AMA was not significant, but the outcome of categorical analysis of two or more positivities on these three markers was significantly higher in hypothyroid patients than in euthyroid patients (28.6% vs. 3.9%, P = 0.024). The combined positivity of preoperative TSH and two or more positivities of TG, ATA, and AMA possess 100% positive predictive value and 81% negative predictive value.
The incidence of hypothyroidism following thyroid lobectomy was 21.1%. High-normal preoperative TSH and two or more positivities for TG, ATA, and AMA are good pre-operative predictive markers. Such high-risk patients need close TSH monitoring before the onset of clinical hypothyroidism.
Hypothyroidism; Thyrotropin; Thyroglobulin; Thyroid microsomal antibodies
Although branchial cleft cysts are common, papillary carcinomas arising from them are rare. Here we report a 41-year-old woman with papillary carcinoma originating from a right lateral branchial cleft cyst without any evidence of a papillary carcinoma in the thyroid gland. The patient underwent right lateral neck dissection followed by total thyroidectomy. We then confirmed papillary carcinoma arising from the branchial cleft cyst through microscopic and immunohistochemical staining with thyroglobulin (TG), thyroid-associated transcription factor-1 (TTF-1) and p63. It is the 10th case worldwide describing papillary carcinoma in a branchial cleft cyst with a review of the literature on the features of the disease and discussion of the role of immunohistochemical staining with TG, TTF -1 and p63. In conclusion, it should be emphasized that the surgeon must be cautioned of the possibility of primary papillary carcinoma in the branchial cleft cyst.
Branchioma; Thyroid neoplasms; Papillary carcinoma
A primary cancer causing thyroid metastasis is extremely rare. In western countries, the most common primary tumors causing thyroid metastases include kidney, lung, breast, and gastrointestinal cancers. In contrast, breast is the most common primary site, followed by kidney, colon, and lung cancers in Korea. To the best of our knowledge, surgically confirmed thyroid metastasis from cholangiocarcinoma has not been reported. Herein, we report the first case of thyroid metastasis secondary to cholangiocarcinoma on which surgery was performed.
Presentation of case
A 55-year-old man was diagnosed with hepatic malignancy in December 2008. He subsequently received 2 cycles of transarterial chemoembolization and 4 cycles of radio-frequency ablation between 2008 and 2010. At follow-up in January 2011, brain metastasis was identified in the right parietal area secondary to cholangiocarcinoma. In April 2011, the patient was found to have palpable masses on the left thyroid and lateral neck. The patient subsequently underwent total thyroidectomy followed by left radical neck dissection. Intraoperatively, an ill-defined mass measuring 6.0 cm was found infiltrating the subcutaneous tissue into the prevertebral fascia. Microscopic and immunohistochemical findings confirmed that the thyroid masses and lymph nodes were metastatic cholangiocarcinoma.
Positive immunohistochemical staining for cytokeratin 7, cytokeratin 19, and AFP and negative results for TG, TTF-1, and cytokeratin 20 can be definitely helpful in arriving at a correct diagnosis.
To the best of our knowledge, this is the first case report on surgically resected thyroid and lateral neck metastases secondary to cholangiocarcinoma.
Neoplasm metastasis; Thyroid metastasis; Cholangiocarcinoma
Hapten induced contact hypersensitivity (CHS) in the skin is a delayed type cellular immune response which can be mediated by CD8+ T cells that produce IFN-γ or IL-17. However, mechanisms for these cytokines in the elicitation of CHS remain to be fully elucidated. Here we show that adoptive transfer of CHS with hapten primed wild type CD8+ T cells is reduced in IFN-γR−/− or IL-17R−/− mice compared to wild type controls. The infiltration of granulocytes and macrophages in the hapten challenged skin of IL-17R−/− recipients is significantly reduced whereas it is less affected in IFN-γR−/− recipients although CD8+ T cell infiltration is inhibited in both recipients. In contrast, the activity of reactive oxidative species is significantly inhibited in IFN-γR−/− but is less affected in IL-17R−/− recipients. Further analysis reveals that the expression of chemokines and cytokines is differentially regulated in the hapten challenged skin of IFN-γR−/− or IL-17R−/− recipients compared to wild type controls. Interestingly, injection of recombinant IL-17 in the skin induces inflammation with a high level of leukocyte infiltration whereas injection of IFN-γ induces inflammation with a high level of reactive oxidative species. Moreover, neutralization of IL-17 in IFN-γR−/− or IFN-γ in IL-17R−/− mice further suppresses the adoptive transfer of CHS by hapten primed wild type CD8+ T cells. The study demonstrates that IFN-γ and IL-17 mediate the elicitation of CHS by different mechanisms and that both cytokines are required for optimal responses. This outcome improves understanding of pathogenesis and provides new insights into therapeutic strategies for CHS.
Rodent; Skin; T cells; Inflammation; Cytokine
Allergen induced contact hypersensitivity (CHS) is a T cell mediated delayed type immune response which has been considered to be primarily mediated by CD8+ Tc1 cells. IFN-γ, the prototype Tc1 (Th1) cytokine, has been implicated as the primary inflammatory cytokine for CHS. In this report, we demonstrate that neutralization of IL-17 rather than IFN-γ suppresses the elicitation of CHS. The suppression does not result from inhibition of the proliferation of allergen-activated T cells. Allergen sensitization induces the development of distinct CD8+ T cell subpopulations that produce IFN-γ or IL-17. While CD8+ IL-17 producing cells are stimulated by IL-23, they are inhibited by IL-12, a prototypical stimulator of IFN-γ producing Tc1 cells. This indicates that CD8+ IL-17 producing cells are distinct from Tc1 cells and are important in effector functions at the elicitation of CHS. The studies provide insights into a novel mechanism for CHS.
Rodent; Skin; T cells; Inflammation; Cytokine
Cholangioscopy not only enables the direct visualization of the biliary tree, but also allows for forceps biopsy to diagnosis early cholangiocarcinoma. Recently, some reports have suggested the clinical usefulness of direct peroral cholangioscopy (POC) using an ultra-slim endoscope with a standard endoscopic unit by a single operator. Enhanced endoscopy, such as narrow band imaging (NBI), can be helpful for detecting early neoplasia in the gastrointestinal tract and is easily applicable during direct POC. A 63-year-old woman with acute cholangitis had persistent bile duct dilation on the left hepatic duct after common bile duct stone removal and clinical improvement. We performed direct POC with NBI using an ultra-slim upper endoscope to examine the strictured segment. NBI examination showed an irregular surface and polypoid structure with tumor vessels. Target biopsy under direct endoscopic visualization was performed, and adenocarcinoma was documented. The patient underwent an extended left hepatectomy, and the resected specimen showed early bile duct cancer confined to the ductal mucosa.
Early bile duct cancer; Direct peroral cholangioscopy; Narrow band imaging
Narrow band imaging (NBI) is a new technique that uses optical filters for imaging of mucosal morphology. The aim of this study was to correlate findings of NBI with magnifying colonoscopy and histology for prediction of neoplastic colorectal lesion.
Between September 2005 and December 2007, 107 colon polyps from 68 patients were detected by conventional colonoscopy and subsequently evaluated by NBI with magnifying colonoscopy and analyzed for a pit pattern and a capillary pattern. More analysis was done regarding thickness and irregularity of capillary features.
Pit pattern with NBI magnification to discriminate between neoplastic and non-neoplastic lesions had a sensitivity of 88.9% and a specificity of 87.5%; capillary pattern yielded test performance characteristics of 91.9% and 87.5%. In respect of capillary thickness, invisible capillaries were found significantly more often in hyperplastic lesions. All thick capillaries were found in neoplastic polyps, and found significantly more often in carcinomas with submucosal massive invasion (sm-m) (p<0.01). In respect of capillary irregularity, invisible capillaries were found significantly more often in hyperplasic lesions, and severely irregular capillaries were found significantly more often in sm-m lesions (p<0.01).
Observation of capillary thickness and irregularity by NBI magnification is useful for correlating histological grade with carcinoma, especially with depth of submucosal invasion.
Narrow band imaging; Magnifying colonoscopy; Histology; Colorectal tumor
von Meyenburg complexes; Cholangiocarcinoma; Liver
A 54 year old man was referred to our hospital with gastric cancer. The patient had a history of splenectomy and a left nephrectomy as a result of a traffic accident 15 years earlier. The endoscopic findings were advanced gastric cancer at the lower body of the stomach. Abdominal ultrasonography (USG) and magnetic resonance imaging demonstrated a metastatic nodule in the S2 segment of the liver. Eventually, the clinical stage was determined to be cT2cN1cM1 and a radical distal gastrectomy, lateral segmentectomy of the liver were performed. The histopathology findings confirmed the diagnosis of intrahepatic splenosis, omental splenosis. Hepatic splenosis is not rare in patients with a history of splenic trauma or splenectomy. Nevertheless, this is the first report describing a patient with gastric cancer and intrahepatic splenosis that was misinterpreted as a liver metastatic nodule. Intra-operative USG guided fine needle aspiration should be considered to avoid unnecessary liver resections in patients with a suspicious hepatic metastasis.
Stomach neoplasms; Splenosis; Neoplasm metastasis; Liver
Concern regarding the health-related quality of life (HRQOL) of long-term survivors of thyroid cancer has risen due to the rapid increase in the incidence of thyroid cancer, which generally has an excellent prognosis. The aim of this study was to evaluate the status of HRQOL in disease-free survivors of differentiated thyroid carcinoma (DTC) and to evaluate the important determinants of HRQOL.
This was a cross-sectional study in which we interviewed consecutive disease-free survivors of DTC. Three different validated questionnaires ("EORTC QLQ-C30" for various functional domains, the "brief fatigue inventory (BFI)" and the "hospital anxiety and depression scale" (HADS)) were used. Data from a large, population based survey of 1,000 people were used as a control.
The response rate for the questionnaires was 78.9% (316/401). Disease-free survivors of DTC showed a decreased HRQOL in all five functional domains (physical, role, cognitive, emotional, and social) on the EORTC QLQ-C30 compared with controls (P < 0.01). BFI and HADS-anxiety scores also showed greater distress in disease-free survivors of DTC than in controls (P < 0.05). A multiple regression analysis for the determinants of HRQOL showed that the HADS-anxiety, HADS-depression, and BFI scores were the most significant components of decreased HRQOL.
Although disease-free survivors of DTC are expected to have disease-specific survival comparable to the general population, they experience a significantly decreased HRQOL. Anxiety, depression, and fatigue were the major determinants of the decreased HRQOL. Supportive psychological care should be integrated into the management of long-term survivors of DTC.
Resistance to thyroid hormone (RTH) is an autosomal dominant hereditary disorder that is difficult to diagnose because of its rarity and variable clinical features. The magnitude of RTH is caused by mutations in the thyroid hormone receptor beta (TRβ) gene. We recently treated a 38-yr-old woman with RTH who had incidental papillary thyroid carcinoma. She presented with goiter and displayed elevated thyroid hormone levels with an unsuppressed TSH. She was determined to harbor a missense mutation of M310T in exon 9 of the TRβ gene, and diagnosed with generalized RTH. This mutation has not yet been reported in Korea. RTH is very rare and easily overlooked, but should be considered in patients who present with goiter and elevated thyroid hormone levels with an unsuppressed TSH. The association between thyroid cancer and RTH needs further study.
Thyroid Hormone Resistance Syndrom; Thyroid Hormone Receptor; Thyroid Hormone Receptors beta; Mutation; Thyroid Neoplasms
The existence of an association between lung function and metabolic syndrome (MetS) has been debated in cases involving non-obese subjects. To address this debate, we performed a cross-sectional study to investigate the association between lung function and MetS in both obese and non-obese populations.
The present study consisted of a total of 1,951 Korean male subjects. In this study group, we investigated relationships between lung function and MetS risk factors such as fasting serum glucose, systolic blood pressure (SBP), insulin resistance index, waist circumference (WC), and hemoglobin A1C level.
Forced vital capacity (FVC) values were significantly lower in the MetS group compared with those of the non-MetS group. In both non-obese (body mass index [BMI] < 25 kg/m2) and obese subjects (BMI ≥ 25 kg/m2), fasting serum glucose, hemoglobin A1C level, insulin resistance index, SBP, WC, and the prevalences of diabetes and MetS were significantly higher in subjects in the lowest FVC quartile compared with those in the highest FVC quartile. Odds ratios for the presence of MetS risk factors, after adjusting for age and height, ranged from 1.21 to 1.39 (P < 0.01) for a one standard deviation decrease in FVC.
The results of our study suggest that decreased vital capacity in Korean adult male subjects is associated with MetS, irrespective of obesity.
FEV1; FVC; Insulin resistance; Metabolic syndrome
We describe a 39-year-old man with spontaneous rupture of a gastric stromal tumor causing hemoperitoneum. Ultrasonography showed a large mass broadly abutting the stomach and liver. Computed tomography demonstrated a heterogeneous enhanced mass arising from the stomach and focal perforation of the tumor with hemoperitoneum; endoscopic ultrasonography showed an exophytic heterogeneous mass originating from the gastric muscle layer. Angiography revealed that the right gastric artery was the main artery supplying the tumor. A gastric stromal tumor with bloody fluid in the peritoneal cavity was seen at the laparotomy. The tumor was excised completely, and subsequent histological and immunohistochemical studies indicated that it was a gastric stromal tumor. We report a relatively rare case of gastric stromal tumor causing hemoperitoneum due to spontaneous rupture of the tumor.
Gastric stromal tumor; Hemoperitoneum; Spontaneous rupture
To determine the feasibility of using T2 mapping as a quantitative method to longitudinally follow the disease activity in children with Duchenne muscular dystrophy (DMD) who are treated with steroids.
Materials and Methods
Eleven boys with DMD (age range: 5-14 years) underwent evaluation with the clinical functional score (CFS), and conventional pelvic MRI and T2 mapping before and during steroid therapy. The gluteus muscle inflammation and fatty infiltration were evaluated on conventional MRI. The histograms and mean T2 relaxation times were obtained from the T2 maps. The CFS, the conventional MRI findings and the T2 values were compared before and during steroid therapy.
None of the patients showed interval change of their CFSs. On conventional MRI, none of the images showed muscle inflammation. During steroid treatment, two boys showed increased fatty infiltration on conventional MRI, and both had an increase of the mean T2 relaxation time (p < 0.05). The remaining nine boys had no increase in fatty infiltration. Of these, three showed an increased mean T2 relaxation time (p < 0.05), two showed no change and four showed a decreased mean T2 relaxation time (p < 0.05).
T2 mapping is a feasible technique to evaluate the longitudinal muscle changes in those children who receive steroid therapy for DMD. The differences of the mean T2 relaxation time may reflect alterations in disease activity, and even when the conventional MRI and CFS remain stable.
Magnetic resonance (MR); Duchenne muscular dystrophy (DMD); Muscle; T2 relaxation time map
The effect of monovalent ions on both the reactivity and global folding of the 8–17 DNAzyme is investigated and the results are compared with the hammerhead ribozyme, which has similar size and secondary structure. In contrast to the hammerhead ribozyme, the 8–17 DNAzyme activity is not detectable in the presence of 4 M K+, Rb+, and Cs+ and the complex, [Co(NH3)6]3+. Only Li+, NH4+ and to a lesser extent Na+ showed detectable activity. The observed rate constants (kobs ~10−3 min−1 for Li+ and NH4+) are ~1000-fold lower than that in the presence of 10 mM Mg2+, and ~200,000-fold slower than the estimated rate in the presence of 100 µM Pb2+. Since the hammerhead ribozyme displays monovalent ion-dependent activity that is often within ~10-fold of divalent metal ion-dependent activity, these results suggest that the 8–17 DNAzyme, obtained by in vitro selections has evolved to have a more stringent divalent metal ion requirement for high activity as compared to the naturally occurring ribozymes, making the 8–17 DNAzyme an excellent choice as a Pb2+ sensor with high selectivity. In contrast to the activity data, folding was observed in the presence of all the monovalent ions investigated, although those monovalent ions that do not support DNAzyme activity have weaker binding affinity (Kd ~0.35 M for Rb+ and Cs+), while those that confer DNAzyme activity possess stronger affinity (Kd ~0.22 M for Li+, Na+ and NH4 +). In addition, a correlation between metal ion charge density, binding affinity and enzyme activity was found among mono- and divalent metal ions except Pb2+; higher charge density resulted in stronger affinity and higher activity, suggesting that the observed folding and activity is at least partially due to electrostatic interactions between ions and the DNAzyme. Finally, circular dichroism (CD) study has revealed Z-DNA formation with the monovalent metal ions, Zn2+ and Mg2+; the Kd values obtained using CD were in the same range as those obtained from folding studies using FRET. However, Z-DNA formation was not observed with Pb2+. These results indicate that Pb2+-dependent function follows a different mechanism from the monovalent metal ions and other divalent metal ions; in the presence of latter metal ions, metal-ion dependent folding and structural changes, including formation of Z-DNA, play an important role in the catalytic function of the 8–17 DNAzyme.
8–17 DNAzyme; Monovalent ions; Activity; Fluorescence Resonance Energy Transfer (FRET); Circular Dichroism (CD)