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Back K, Kim TH, Lee J, Kim JS, Choe JH, Oh YL, Cho A, Kim JH. Optimal value of lymph node ratio and metastatic lymph node size to predict risk of recurrence in pediatric thyroid cancer with lateral neck metastasis. J Pediatr Surg 2023; 58:568-573. [PMID: 35973863 DOI: 10.1016/j.jpedsurg.2022.07.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 06/03/2022] [Accepted: 07/05/2022] [Indexed: 10/17/2022]
Abstract
BACKGROUND No specific guideline exists for risk stratification based on lymph node (LN) status in pediatric thyroid cancer. The purpose of our study is to identify optimal values of lymph node ratio (LNR) and largest metastatic LN size for predicting recurrent/persistent disease, especially in children with lateral neck metastasis (N1b). METHODS We conducted a retrospective study from January 1997 to June 2018 at Samsung Medical Center. A total of 50 papillary thyroid carcinoma (PTC) patients who underwent total thyroidectomy + both central neck dissection (CND) + modified radical neck dissection (MRND) (unilateral or bilateral) was enrolled. RESULTS The median follow-up duration was 60.8 months (range, 6.2-247 months). The mean age was 14.6 years, and the mean tumor size was 2.9 cm. Mean size of the largest metastatic LN was 1.5 cm. Mean value of central LNR was 0.6, and mean value of lateral LNR was 0.3. Largest metastatic LN size [HR = 2.0 (95% CI 1.0-4.0), p = 0.040] and lateral LNR [HR = 43.6 (95% CI 2.2-871.0), p = 0.014] were significant prognostic factors for recurrence. The optimal combination of lateral LNR and largest metastatic LN size to predict recurrence were 0.3 and 2.5 cm, respectively, with the largest AUC (AUC at 60 months = 77.4) and significant p-value (p = 0.009 and p = 0.021) (Table 3). Kaplan-Meier curves showed significant differences in recurrence-free survival (RFS) rates among four groups (Fig. 2A,2B). CONCLUSIONS In pediatric PTC patients with N1b, lateral LNR and largest metastatic LN size are significant predictors for recurrence. Children with lateral LNR > 0.3 or any metastatic lymph node > 2.5 cm in the largest dimension have higher risk for recurrence. Children are classified as extensive N1b if lateral LNR > 0.3 or pathologic N1 with largest LN size > 2.5 cm, and vice versa.
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Affiliation(s)
- Kyorim Back
- Division of Endocrine Surgery, Department of Surgery, Chung-Ang University Hospital, Chung-Ang University School of Medicine, Seoul, Korea
| | - Tae Hyuk Kim
- Division of Endocrinology & Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jiyeon Lee
- Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Korea
| | - Jee Soo Kim
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jun-Ho Choe
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Young Lyun Oh
- Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Korea
| | - Anna Cho
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jung-Han Kim
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
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Back K, Song RY, Choe JH, Kim JS, Choi YS, Kim MK, Kim JH. The clinical impact of extrathyroidal extensions on prognoses in pediatric differentiated thyroid cancers. J Pediatr Surg 2022; 57:1532-1537. [PMID: 34758908 DOI: 10.1016/j.jpedsurg.2021.09.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/31/2021] [Accepted: 09/16/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND The prognostic impact of extrathyroidal extensions (ETE) on clinical outcomes has not been well studied in pediatric thyroid cancers. The aim of this study was to analyze the clinicopathological characteristics and clinical outcomes according to the extent of ETE in pediatric and adolescent thyroid cancers. METHODS This study retrospectively reviewed 89 papillary thyroid carcinoma (PTC) patients less than 19 years of age who underwent total thyroidectomy with central neck dissections (CND) between 1997 and 2018. We compared the clinicopathological features among three groups: no ETE, microscopic ETE, and gross ETE. RESULTS The median follow-up time was 111 months. The mean age was 15.3 years and the mean tumor size was 2.4 cm. Tumor sizes larger than 2 cm (OR = 9.2, p = 0.001), exhibited bilaterality (OR = 4.3, p = 0.006), were an aggressive variant (OR = 5.8, p = 0.006), and exhibited central lymph node metastasis (OR = 1.3, p = 0.018), lateral lymph node metastasis (OR = 9.2, p = 0.001), recurrence (OR = 3.9, p = 0.038), and distant metastasis (OR = 4.4, p = 0.016) were associated with gross ETE. There was no remarkable difference in clinicopathological characteristics between the no ETE group and microscopic ETE group, except for aggressive variants (OR = 5.5, p = 0.008). There was a significant difference in recurrence-free survival (RFS) rates according to the extent of ETE (p = 0.025). Furthermore, the distant metastasis-free survival curve presented a significant difference among the three groups (p = 0.018). Both microscopic ETE and gross ETE were significantly associated with worse prognoses in pediatric thyroid cancers. CONCLUSIONS We recommend that microscopic ETE should be included in the intermediate risk category and that gross ETE should be stratified in the high risk group in future revisions of ATA pediatric guidelines.
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Affiliation(s)
- Kyorim Back
- Department of Surgery, Division of Endocrine Surgery, Chung-Ang University Hospital, Chung-Ang University School of Medicine, 102 Heukseok-ro, Dongjak-gu, Seoul 06973, South Korea.
| | - Ra-Yeong Song
- Department of Surgery, Division of Endocrine Surgery, Chung-Ang University Hospital, Chung-Ang University School of Medicine, 102 Heukseok-ro, Dongjak-gu, Seoul 06973, South Korea
| | - Jun-Ho Choe
- Department of Surgery, Division of Endocrine Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, South Korea
| | - Jee Soo Kim
- Department of Surgery, Division of Endocrine Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, South Korea
| | - Yoo Shin Choi
- Department of Surgery, Division of Hepatobiliary Surgery, Chung-Ang University Hospital, Chung-Ang University School of Medicine, Seoul, South Korea
| | - Min Kyoon Kim
- Department of Surgery, Division of Breast Surgery, Chung-Ang University Hospital, Chung-Ang University School of Medicine, Seoul, South Korea
| | - Jung-Han Kim
- Department of Surgery, Division of Endocrine Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, South Korea.
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Back K, Lee J, Cho A, Choe JH, Kim JH, Oh YL, Kim JS. Is total thyroidectomy with bilateral central neck dissection the only surgery for papillary thyroid carcinoma patients with clinically involved central nodes? BMC Surg 2022; 22:251. [PMID: 35768863 PMCID: PMC9245244 DOI: 10.1186/s12893-022-01699-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 06/20/2022] [Indexed: 11/17/2022] Open
Abstract
Background In clinical practice, we often observed that patients who underwent total thyroidectomy due to clinically involved nodal disease (cN1a) actually had less extensive CLNM on final pathology. This study investigates whether total thyroidectomy and therapeutic bilateral CND are necessary for all PTC patients with cN1a.
Methods This study retrospectively reviewed 899 PTC patients who underwent total thyroidectomy with bilateral CND from January 2012 to June 2017. The patients were divided into two groups according to pre-operative central lymph node (CLN) status: cN0, no suspicious CLNM; cN1a, suspicious CLNM. We compared the clinicopathological features of these two groups. Results There was no significant difference in recurrence between cN0 and cN1a groups after a mean follow-up time of 59.1 months. Unilateral cN1a was related to the largest central LN size ≥ 2 mm (OR = 3.67, p < 0.001) and number of CLNM > 5(OR = 2.24, p = 0.006). On the other hand, unilateral cN1a was not associated with an increased risk of contralateral lobe involvement (OR = 1.35, p = 0.364) and contralateral CLNM (OR = 1.31, p = 0.359). Among 106 unilateral cN1a patients, 33 (31.1%) were found to be pN0 or had ≤ 5 metastatic CLNs with the largest node smaller than 2 mm. Conclusions Most cN1a patients were in an intermediate risk group for recurrence and required total thyroidectomy. However, lobectomy with CND should have performed in approximately 30% of the cN1a patients. Pre-operative clinical examination, meticulous radiologic evaluation, and intra-operative frozen sections to check the nodal status are prerequisites for this approach.
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Affiliation(s)
- Kyorim Back
- Division of Endocrine Surgery, Department of Surgery, Chung-Ang University Hospital, Chung-Ang University School of Medicine, Seoul, South Korea
| | - Jiyeon Lee
- Department of Pathology and Translational Genomics, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, South Korea
| | - Anna Cho
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, School of Medicine, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul, 06351, South Korea
| | - Jun-Ho Choe
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, School of Medicine, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul, 06351, South Korea
| | - Jung-Han Kim
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, School of Medicine, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul, 06351, South Korea
| | - Young Lyun Oh
- Department of Pathology and Translational Genomics, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, South Korea
| | - Jee Soo Kim
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, School of Medicine, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul, 06351, South Korea.
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Back K, Lee J, Choe JH, Kim JH, Oh YL, Kim JS. Total thyroidectomy can be overtreatment in cN1a papillary thyroid carcinoma patients whose tumor is smaller than 1 cm. Am J Surg 2021; 223:635-640. [PMID: 34446213 DOI: 10.1016/j.amjsurg.2021.08.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/19/2021] [Accepted: 08/10/2021] [Indexed: 12/26/2022]
Abstract
BACKGROUND The 2015 American Thyroid Association (ATA) guidelines recommend pursuing total thyroidectomy with therapeutic central lymph-node dissection (CND) in patients with clinically apparent nodal disease (cN1a), regardless of tumor size. The aim of this study was to investigate whether total thyroidectomy is necessary for thyroid papillary microcarcinoma (PTMC) patients with preoperative unilateral cN1a. METHODS This study included 295 papillary thyroid microcarcinoma patients who underwent total thyroidectomy with bilateral CND from January 2012 to June 2015. RESULTS The median follow-up time was 42.5 months. Locoregional recurrence (LRR) was observed in only two (0.9%) patients. Among 70 cN1a patients, only 19 (27.1%) were at intermediate risk for disease recurrence and required total thyroidectomy per the ATA guidelines. Lobectomy can be considered as a treatment option for the remaining patients (72.9%). CONCLUSIONS Our study showed that more than two-thirds of PTMC patients with clinical nodal disease who underwent total thyroidectomy and CND were actually lobectomy candidates. Total thyroidectomy as the first surgical option for cN1a, especially in PTMC patients, should be reconsidered.
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Affiliation(s)
- Kyorim Back
- Division of Endocrine Surgery, Department of Surgery, Chung-Ang University Hospital, Chung-Ang University School of Medicine, Seoul, South Korea
| | - Jiyeon Lee
- Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, South Korea
| | - Jun-Ho Choe
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, South Korea
| | - Jung-Han Kim
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, South Korea
| | - Young Lyun Oh
- Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, South Korea
| | - Jee Soo Kim
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, South Korea.
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Kim MJ, Back K, Choe JH, Kim JH, Kim JS. Feasibility of lateral sentinel lymph node biopsy in medullary thyroid cancer: A surrogate tool for determining prophylactic lateral neck dissection-A pilot study. Head Neck 2021; 43:3276-3286. [PMID: 34288208 DOI: 10.1002/hed.26808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/28/2021] [Accepted: 07/08/2021] [Indexed: 11/11/2022] Open
Abstract
BACKGROUNDS This study aimed to evaluate usefulness of lateral sentinel lymph node biopsy (SLNB) in determining lateral neck dissection (LND) of patients with medullary thyroid cancer (MTC). METHODS Sixteen patients with MTC were enrolled in the study from January 2013 to June 2019. Intratumoral injection of technetium (Tc)-99m phytate followed by lymphoscintigraphy was performed preoperatively. Lateral sentinel lymph nodes were detected by a collimated gamma probe and underwent frozen analysis. Ipsilateral LND was performed in all patients to assess lateral LN status. RESULTS The identification rate of sentinel lymph nodes (SLNs) detected by radioisotope was 87.5% (14 of 16 patients). The sensitivity, specificity, positive predictive value, and negative predictive value of frozen analyses were 66.7%, 100%, 100%, and 91.6%, respectively. Based on final histopathology, however, the diagnostic values of lateral SLNB were all 100%. CONCLUSIONS This study showed that lateral SLNB can be a promising surgical tool for decisions on LND in patients with MTC.
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Affiliation(s)
- Min Jhi Kim
- Department of Surgery, CHA Ilsan Medical Center, Cha University School of Medicine, Goyang-si, South Korea
| | - Kyorim Back
- Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Jun-Ho Choe
- Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Jung-Han Kim
- Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Jee Soo Kim
- Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
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Back K, Choe JH, Kim JS, Kim JH. Occult contralateral central neck metastasis in papillary thyroid carcinoma with preoperatively documented ipsilateral lateral neck metastasis. Eur J Surg Oncol 2021; 47:1339-1345. [PMID: 33744024 DOI: 10.1016/j.ejso.2021.01.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/12/2020] [Accepted: 01/06/2021] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND This study was conducted to evaluate risk factors and long-term prognosis of contralateral central neck metastasis (CCNM) in papillary thyroid cancer (PTC) patients with ipsilateral lateral neck metastasis. We present clinical evidence to aid in surgical decision-making regarding the extent of central neck dissection (CND), focusing on separation between ipsilateral and contralateral sides. METHODS A total of 379 PTC patients who underwent total thyroidectomy and concomitant bilateral central neck dissection with ipsilateral lateral neck dissection (LND) at a single institution was retrospectively included between January 1997 and December 2015. RESULTS The median follow-up time was 83.2 months, the mean age was 44.3 years, and the mean tumor size was 1.5 cm. Among the study sample, 266 patients were female (70.2%) and 113 (29.8%) were male. Of 379 patients, CCNM was present in 34.6%. In multivariate analysis, male sex (adjusted OR = 2.46, p = 0.002), bilaterality (adjusted OR = 2.58, p = 0.004), number of metastatic ipsilateral central lymph nodes (adjusted OR = 1.15, p = 0.002), number of metastatic lateral lymph nodes (adjusted OR = 1.48, p < 0.001), and three-level metastasis (adjusted OR = 2.46, p = 0.012) were identified as risk factors of CCNM. Overall recurrence occurred in 6.0% and 11.5% of patients in the CCNM (-) group and CCNM (+) group, respectively. In addition, contralateral recurrence was observed in 1.2% patients and 0.8% patients in the CCNM (-) group and CCNM (+) group, respectively. However, CCNM did not significantly increase risk of recurrence (adjusted HR = 1.01, p = 0.981). CONCLUSIONS Although the probability of pathological CCNM is not negligible, CCNM was not associated with higher risk of recurrence. This study suggest that central neck dissection may be limited to the ipsilateral side, and the result regarding prognosis of CCNM may help to avoid bilateral CND so that it could have potential to minimize unnecessary surgery-related complications such as recurrent laryngeal nerve(RLN) injury or hypoparathyroidism.
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Affiliation(s)
- Kyorim Back
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
| | - Jun-Ho Choe
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Jee Soo Kim
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Jung-Han Kim
- Division of Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
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Back K, Kim JS, Kim JH, Choe JH. Superior Located Papillary Thyroid Microcarcinoma is a Risk Factor for Lateral Lymph Node Metastasis. Ann Surg Oncol 2019; 26:3992-4001. [DOI: 10.1245/s10434-019-07587-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Indexed: 12/11/2022]
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Kim SK, Kwon AY, Back K, Park I, Hur N, Lee JH, Choe JH, Kim JH, Oh YL, Kim JS. Predictive Factors of Lymph Node Metastasis in Follicular Variant of Papillary Thyroid Carcinoma. Ann Surg Oncol 2017; 24:2617-2623. [PMID: 28685355 DOI: 10.1245/s10434-017-5912-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Indexed: 11/18/2022]
Abstract
BACKGROUND Compared with conventional papillary thyroid carcinoma (PTC), follicular variant of PTC (FV-PTC) shows less aggressive behavior and better prognosis. Nonetheless, regional lymph node (LN) metastasis was found in 22.8% of FV-PTC patients. Because LN metastasis is a proven predictor of recurrence in PTC, it is important to assess LN metastasis in FV-PTC patients. METHODS We retrospectively reviewed 134 FV-PTC patients who underwent thyroidectomy with neck dissection. RESULTS Central LN metastasis (CLNM) and lateral LN metastasis (LLNM) were found in 50 (37.3%) and 16 (11.9%) patients, respectively. In the multivariate analysis for CLNM, male sex (adjusted OR 4.735, p = 0.001), nonencapsulated form (adjusted OR 2.863, p = 0.022), and tumor size >1.0 cm (adjusted OR 3.157, p = 0.008) were independent predictors of high prevalence of CLNM in FV-PTC patients. In the multivariate analysis for LLNM, microscopic extrathyroidal extension (ETE) (adjusted OR 3.939, p = 0.041) and CLNM (adjusted OR 13.340, p = 0.001) were independent predictors of high prevalence of LLNM in FV-PTC patients. CONCLUSIONS Meticulous perioperative evaluation and prophylactic central neck dissection may be beneficial for FV-PTC patients with male sex, nonencapsulated form, and tumor size >1.0 cm. Moreover, cautious perioperative evaluation of lateral neck LN may be mandatory for FV-PTC patients with microscopic ETE and CLNM.
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Affiliation(s)
- Seo Ki Kim
- Division of Breast and Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Ah-Young Kwon
- Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Kyorim Back
- Division of Breast and Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Inhye Park
- Division of Breast and Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Nayoon Hur
- Division of Breast and Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Jun Ho Lee
- Division of Breast and Endocrine Surgery, Department of Surgery, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, South Korea
| | - Jun-Ho Choe
- Division of Breast and Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
| | - Jung-Han Kim
- Division of Breast and Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Young Lyun Oh
- Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Jee Soo Kim
- Division of Breast and Endocrine Surgery, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
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Lainé AL, Price D, Davis J, Roberts D, Hudson R, Back K, Bungay P, Flanagan N. Enhanced oral delivery of celecoxib via the development of a supersaturable amorphous formulation utilising mesoporous silica and co-loaded HPMCAS. Int J Pharm 2016; 512:118-125. [DOI: 10.1016/j.ijpharm.2016.08.034] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/10/2016] [Accepted: 08/15/2016] [Indexed: 11/15/2022]
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Kang S, Kang K, Lee K, Back K. Characterization of tryptamine 5-hydroxylase and serotonin synthesis in rice plants. Plant Cell Rep 2007; 26:2009-15. [PMID: 17639402 DOI: 10.1007/s00299-007-0405-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Revised: 06/20/2007] [Accepted: 06/25/2007] [Indexed: 05/16/2023]
Abstract
Serotonin is a well-known pineal hormone that in mammals plays a key role in mood. In plants, serotonin is implicated in several physiological roles such as flowering, morphogenesis, and adaptation to environmental changes. However, its biosynthetic enzyme in plants has not been characterized. Therefore, we measured the serotonin content and enzyme activity responsible for serotonin biosynthesis in rice seedlings. Tryptamine 5-hydroxylase (T5H), which converts tryptamine into serotonin, was found as a soluble enzyme that had maximal activity in the roots. The maximal activity of T5H was closely associated with the enriched synthesis of serotonin in roots. Tetrahydropterine-dependent T5H activity was inhibited by tyramine, tryptophan, 5-OH-tryptophan, and octopamine, but remained unaltered by dopamine in vitro. The tissues of rice seedlings grown in the presence of tryptamine exhibited a dose-dependent increase in serotonin in parallel with enhanced T5H enzyme activity. However, no significant increase in serotonin was observed in rice tissues grown in the presence of tryptophan, suggesting that tryptamine is a bottleneck intermediate substrate for serotonin synthesis.
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Affiliation(s)
- S Kang
- Department of Molecular Biotechnology, College of Agriculture and Life Sciences, Agricultural Plant Stress Research Center, Biotechnology Research Institute, Chonnam National University, Gwangju 500-757, South Korea
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Nah J, Song SJ, Back K. Partial characterization of farnesyl and geranylgeranyl diphosphatases induced in rice seedlings by UV-C irradiation. Plant Cell Physiol 2001; 42:864-867. [PMID: 11522913 DOI: 10.1093/pcp/pce102] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This study reports the identification and characterization of allyl diphosphatases (EC 3.1.7.1) in plants by using rice seedlings. Two distinct Mg(2+)-independent allyl diphosphatases, which convert farnesyl diphosphate (FDP) and geranylgeranyl diphosphate (GGDP) into farnesol and geranylgeraniol, respectively, were induced in rice seedlings irradiated with UV-C. Farnesyl diphosphatase (FDPase) and geranylgeranyl diphosphatase (GGDPase) are located in the microsomal fraction. The relative specific activity of FDPase was much higher than the specific activity of GGDPase. FDPase activity was inhibited by GGDP (50% inhibition at 5 microM) and geranyl diphosphate (50% inhibition at 100 microM). In contrast, GGDPase activity was inhibited 50% by 50 microM isopentenyl diphosphate or 100 microM FDP. The optimal pH for FDPase was 6.3 and for GGDPase was 7.9.
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Affiliation(s)
- J Nah
- Department of Genetic Engineering, Agricultural Plant Stress Research Center, Chonnam National University, Kwangju, 500-757 South Korea
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Back K, Jang SM, Lee BC, Schmidt A, Strack D, Kim KM. Cloning and characterization of a hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)transferase induced in response to UV-C and wounding from Capsicum annuum. Plant Cell Physiol 2001; 42:475-81. [PMID: 11382813 DOI: 10.1093/pcp/pce060] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Hydroxycinnamoyl-CoA : tyramine N-(hydroxycinnamoyl) transferase (THT) is a pivotal enzyme in the synthesis of N-(hydroxycinnamoyl)-amines, which are associated with cell wall fortification in plants. The cDNA encoding THT was cloned from the leaves of UV-C treated Capsicum annuum (hot pepper) using a differential screening strategy. The predicted protein encoded by the THT cDNA is 250 amino acids in length and has a relative molecular mass of 28,221. The protein sequence derived from the cDNA shares 76% and 67% identity with the potato and tobacco THT protein sequences, respectively. The recombinant pepper THT enzyme was purified using a bacterial overexpression system. The purified enzyme has a broad substrate specificity including acyl donors such as cinnamoyl-, sinapoyl-, feruloyl-, caffeoyl-, and 4-coumaroyl-CoA and acceptors such as tyramine and octopamine. In UV-C treated plants, the THT mRNA was strongly induced in leaves, and the elevated level of expression was stable for up to 36 h. THT mRNA also increased in leaves that were detached from the plant but not treated with UV-C. THT expression was measured in different plant tissues, and was constitutive at a similar level in leaf, root, stem, flower and fruit. Induction of THT mRNA was correlated with an increase in THT protein.
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Affiliation(s)
- K Back
- Department of Genetic Engineering, Biotechnology Research Institute, Chonnam National University, Kwangju, 500-757 South Korea.
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Lee MJ, Han O, Back K, Choi YJ, Baik MG. Induction of Lysozyme Gene Expression During Involution of Mouse Mammary Gland. Asian Australas J Anim Sci 2001. [DOI: 10.5713/ajas.2001.462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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14
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Shin HJ, Lee DE, Shin DH, Kim KU, Kim HY, Ohashi Y, Han O, Baik MG, Back K. Molecular cloning and cultivar specific expression of MAP kinases from Capsicum annuum. Mol Cells 2001; 11:48-54. [PMID: 11266120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
Two MAP kinases, MK1 and MK2, were cloned from Capsicum annuum (pepper) cv. Subicho using a parsley MAP kinase gene as a heterologous probe. MK1 and MK2 encode stress-inducible protein kinases that can contribute to the response to wounding, UV-C, and cold. MK1 has a 92% amino acid identity with WIPK of tobacco. It was transcriptionally induced in response to wounding. In contrast, no detectable MK1 transcript was found in unwounded leaves of pepper. MK2 has a high level of amino acid homology to MAP kinases, such as NTF4 and SIPK and was constitutively expressed in all tissues. Both MK transcripts were downregulated by UV-C treatment. Each MK protein activation was independently wound-inducible in a cultivar dependent manner. MK1 is phosphorylated in cv. Pungchon but not cv. Subicho; whereas, the MK2 protein activation by wounding is restricted to cv. Subicho. In addition, de novo synthesis of the MK1 protein and tyrosine phosphorylation was rapidly and transiently induced in cv. Pungchon by wounding. In contrast, it is highly unlikely that the MK1 protein is produced in cv. Subicho, even though there is an abundant expression of MK1 mRNA after wounding in this cultivar. In Escherichia coli, which overexpresses MK1, autophosphorylation is observed at conserved threonine and tyrosine phosphorylation sites.
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Affiliation(s)
- H J Shin
- Department of Genetic Engineering, Biotechnology Research Institute, Chonnam National University, Kwangju, Korea
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15
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Lee HJ, Lee SB, Chung JS, Han SU, Han O, Guh JO, Jeon JS, An G, Back K. Transgenic rice plants expressing a Bacillus subtilis protoporphyrinogen oxidase gene are resistant to diphenyl ether herbicide oxyfluorfen. Plant Cell Physiol 2000; 41:743-749. [PMID: 10945344 DOI: 10.1093/pcp/41.6.743] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Protoporphyrinogen oxidase (Protox), the penultimate step enzyme of the branch point for the biosynthetic pathway of Chl and hemes, is the target site of action of diphenyl ether (DPE) herbicides. However, Bacillus subtilis Protox is known to be resistant to the herbicides. In order to develop the herbicide-resistant plants, the transgenic rice plants were generated via expression of B. subtilis Protox gene under ubiquitin promoter targeted to the cytoplasm or to the plastid using Agrobacterium-mediated gene transformation. The integration and expression of the transgene were investigated at T0 generation by DNA and RNA blots. Most transgenic rice plants revealed one copy transgene insertion into the rice genome, but some with 3 copies. The expression levels of B. subtilis Protox mRNA appeared to correlate with the copy number. Furthermore, the plastidal transgenic lines exhibited much higher expression of the Protox mRNA than the cytoplasmic transgenic lines. The transgenic plants expressing the B. subtilis Protox gene at T0 generation were found to be resistant to oxyfluorfen when judged by cellular damage with respect to cellular leakage, Chl loss, and lipid peroxidation. The transgenic rice plants targeted to the plastid exhibited higher resistance to the herbicide than the transgenic plants targeted to the cytoplasm. In addition, possible resistance mechanisms in the transgenic plants to DPE herbicides are discussed.
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Affiliation(s)
- H J Lee
- Biotechnology Research Institute, Chonnam National University, Kwangju, Korea
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16
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Abstract
Sesquiterpene cyclase, the first committed step enzyme from the general isoprenoid building block farnesyl pyrophosphate (FPP) for the synthesis of phytoalexin capsidiol, was isolated from the UV-C treated leaves of Capsicum annuum. This sesquiterpene cyclase, termed as CASC2 showing 77% amino acid identity with the previously cloned sesquiterpene cyclase CASC1, was composed of 560 amino acids with a calculated molecular mass of 64,907. The mRNA expression pattern of CASC2 was very similar to that of CASC1 during the time course of UV-C irradiated leaves of pepper on RNA blot analysis by using each specific probe. The heterologous expression in Escherichia coli using the CASC2 full length failed; however the chimeric construct of CASC2 in which the amino terminal 164 amino acid substituted by the equivalent portion of either CASC1 or tobacco sesquiterpene cyclase was capable of expressing the functional sesquiterpene cyclase activities. The radio-labeled enzymatic products catalyzed by the partially purified chimeric CASC2 were comigrated with authentic radio-labeled sesquiterpene on thin layer chromatography.
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Affiliation(s)
- K Back
- Department of Genetic Engineering, Biotechnology Research Institute, Chonnam National University, Kwangju, Korea.
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17
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Back K. Managed care and the implementation of the State Children's Health Insurance Program. Manag Care Interface 2000; 13:73-6. [PMID: 10747695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
More than two years after its enactment, the Health Care Financing Administration, Baltimore, issued proposed regulations implementing the State Children's Health Insurance Program (SCHIP), enacted under the Balanced Budget Act of 1997. This program was enacted to provide health insurance coverage to the estimated 10 million uninsured children living in the United States. This article provides an overview of SCHIP and how it has been implemented in the various states.
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18
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Back K, He S, Kim KU, Shin DH. Cloning and bacterial expression of sesquiterpene cyclase, a key branch point enzyme for the synthesis of sesquiterpenoid phytoalexin capsidiol in UV-challenged leaves of Capsicum annuum. Plant Cell Physiol 1998; 39:899-904. [PMID: 9816674 DOI: 10.1093/oxfordjournals.pcp.a029452] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Sesquiterpene cyclase, a branch point enzyme in the general isoprenoid pathway for the synthesis of phytoalexin capsidiol, was induced in detached leaves of Capsicum annuum (pepper) by UV treatment. The inducibility of cyclase enzyme activities paralleled the absolute amount of cyclase protein(s) of pepper immunodetected by monoclonal antibodies raised against tobacco sesquiterpene cyclase. A cDNA library was constructed with poly(A)+ RNA isolated from 24 h UV-challenged leaves of pepper. A cDNA clone for sesquiterpene cyclase in pepper was isolated by using a tobacco 5-epi aristolochene synthase gene as a heterologous probe. The predicted protein encoded by this cDNA was comprised of 559 amino acids and had a relative molecular mass of 65,095. The primary structural information from the cDNA clone revealed that it shared 77%, 72% and 49% identity with 5-epi aristolochene, vetispiradiene, and cadinene synthase, respectively. The enzymatic product catalyzed by the cDNA clone in bacteria was identified as 5-epi aristolochene, as judged by argentation TLC. RNA blot hybridization demonstrated the induction of an mRNA consistent with the induction of cyclase enzyme activity in UV-treated pepper.
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Affiliation(s)
- K Back
- Department of Genetic Engineering, Chonnam National University, Kwangju, South Korea
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19
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Devarenne TP, Shin DH, Back K, Yin S, Chappell J. Molecular characterization of tobacco squalene synthase and regulation in response to fungal elicitor. Arch Biochem Biophys 1998; 349:205-15. [PMID: 9448707 DOI: 10.1006/abbi.1997.0463] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The enzyme squalene synthase (SS) represents the first commitment of carbon from the general isoprenoid pathway toward sterol biosynthesis and is a potential point for regulation of sterol biosynthesis. The isolation and characterization of tobacco (Nicotiana tabacum) squalene synthase (TSS) cDNA and genomic DNA clones, as well as determination of the steady state level of TSS mRNA in response to elicitor treatment, were investigated. cDNA clones for TSS were isolated from poly (A)+ RNA using a reverse transcription/polymerase chain reaction (RT/PCR) method. A 1233-bp cDNA clone was generated that contained an open reading frame of 411 amino acids giving a predicted molecular mass of 46.9 kDa. Comparison of the TSS deduced amino acid sequence with currently described SS from different species showed the highest identify with Nicotiana benthamiana (97%), followed by Glycyrrhiza glabra (81%), Arabidopsis thaliana (74%), rat (40%), and yeast (37%). Expression of a soluble form of the TSS enzyme with enzymatic activity in Escherichia coli was achieved by truncating 24 hydrophobic amino acids at the carboxy terminus. Characterization of genomic TSS (gTSS) revealed a gene of 7.086 kb with a complex organization of small exons and large introns not typical of plant genes. Southern blot hybridization indicated only two copies of the SS gene in the tobacco genome. Treatment of tobacco cell suspension cultures with a fungal elicitor dramatically reduced TSS enzymatic activity, lowering it to zero within 24 h. Analysis of TSS mRNA levels, by RNA blot hybridization and primer extension assays, in elicitor-treated cells indicated that the transcript level remained largely unchanged over this 24-h period. These results suggest that the suppression of TSS enzyme activity in elicitor-treated cells may result from a posttranscriptional modification of TSS.
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Affiliation(s)
- T P Devarenne
- Agronomy Department, University of Kentucky, Lexington 40546-0091, USA
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20
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Yin S, Mei L, Newman J, Back K, Chappell J. Regulation of sesquiterpene cyclase gene expression. Characterization of an elicitor- and pathogen-inducible promoter. Plant Physiol 1997; 115:437-51. [PMID: 9342864 PMCID: PMC158501 DOI: 10.1104/pp.115.2.437] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The promoter for a tobacco (Nicotiana tabacum) sesquiterpene cyclase gene, a key regulatory step in sesquiterpene phytoalexin biosynthesis, has been analyzed. The EAS4 promoter was fused to the beta-glucuronidase (GUS) reporter gene, and the temporal and spatial expression patterns of GUS activity were examined in stably transformed plants and in transient expression assays using electroporated protoplasts of tobacco. No GUS activity was observed in any tissues under normal growth conditions. A low level of GUS activity was detected in wounded leaf, root, and stem tissues, whereas a much higher level was observed when these tissues were challenged with elicitors or microbial pathogens. The GUS expression pattern directed by the EAS4 promoter was identical to the induction patterns observed for the endogenous sesquiterpene cyclase genes. Neither exogenous salicylic acid nor methyl jasmonate induced GUS expression; and H2O2 induced GUS expression to only a limited extent. Although the EAS4 promoter contains cis-sequences resembling previously identified transcriptional control motifs, other cis-sequences important for quantitative and qualitative gene expression were identified by deletion and gain-of-function analyses. The EAS4 promoter differs from previously described pathogen-/elicitor-inducible promoters because it only supports inducible gene expression and directs unique spatial expression patterns.
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Affiliation(s)
- S Yin
- Plant Physiology/Biochemistry/Molecular Biology Program, University of Kentucky, Lexington 40546-0091, USA
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21
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Abstract
Terpene cyclases catalyze the synthesis of cyclic terpenes with 10-, 15-, and 20-carbon acyclic isoprenoid diphosphates as substrates. Plants have been a source of these natural products by providing a homologous set of terpene synthases. The crystal structures of 5-epi-aristolochene synthase, a sesquiterpene cyclase from tobacco, alone and complexed separately with two farnesyl diphosphate analogs were analyzed. These structures reveal an unexpected enzymatic mechanism for the synthesis of the bicyclic product, 5-epi-aristolochene, and provide a basis for understanding the stereochemical selectivity displayed by other cyclases in the biosynthesis of pharmacologically important cyclic terpenes. As such, these structures provide templates for the engineering of novel terpene cyclases.
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Affiliation(s)
- C M Starks
- Structural Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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22
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Abstract
An Escherichia coli expression system was used to generate hexahistidyl-tagged plant sesquiterpene cyclases, which were readily purified by a single affinity chromatographic step. Genes for Hyoscyamus muticus vetispiradiene synthase (HVS), a chimeric 5-epi-aristolochene synthase (CH3), and a chimeric sesquiterpene cyclase possessing multifunctional epi-aristolochene and vetispiradiene activity (CH4) were expressed in bacterial cells, which resulted in the sesquiterpene cyclases accumulating to 50% of the total protein and 35% of the soluble protein. From initial velocity experiments, the Michaelis constant for HVS was 3.5 microM, while CH3 and CH4 exhibited smaller values of 0.7 and 0.4 microM, respectively. Steady-state catalytic constants were from 0.02 to 0.04 s-1. A combination of pre-steady-state rapid quench experiments, isotope trapping experiments, and experiments to measure the burst rate constant as a function of substrate concentration revealed that turnover in all three cyclases is limited by a step after the initial chemical step involving rupture of the carbon-oxygen bond in farnesyl diphosphate (FPP). Rate constants for the limiting step were 10-70-fold smaller than for the initial chemical step. Dissociation constants for the enzyme-substrate complex (20-70 microM) were determined from the pre-steady-state experiments and were significantly larger than the observed Michaelis constants. A mechanism that involves an initial, rapid equilibration of enzyme with substrate to form an enzyme-substrate complex, followed by a slower conversion of FPP to an enzyme-bound hydrocarbon and a subsequent rate-limiting step, is proposed for the three enzymes. Interestingly, the multifunctional chimeric enzyme CH4 exhibited both a tighter binding of FPP and a faster conversion of FPP to products than either of its wild-type parents.
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Affiliation(s)
- J R Mathis
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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Back K. Antitrust's expanding universe. Health Syst Rev 1996; 29:11-2, 14. [PMID: 10167137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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24
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Starks C, Back K, Chappell J, Noel J. Structural study of sesquiterpene cyclases. Acta Crystallogr A 1996. [DOI: 10.1107/s0108767396094366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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25
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Abstract
Cyclic terpenes and terpenoids are found throughout nature. They comprise an especially important class of compounds from plants that mediate plant- environment interactions, and they serve as pharmaceutical agents with antimicrobial and anti-tumor activities. Molecular comparisons of several terpene cyclases, the key enzymes responsible for the multistep cyclization of C10, C15, and C20 allylic diphosphate substrates, have revealed a striking level of sequence similarity and conservation of exon position and size within the genes. Functional domains responsible for a terminal enzymatic step were identified by swapping regions approximating exons between a Nicotiana tabacum 5-epi-aristolochene synthase (TEAS) gene and a Hyoscyamus muticus vetispiradiene synthase (HVS) gene and by characterization of the resulting chimeric enzymes expressed in bacteria. While exon 4 of the TEAS gene conferred specificity for the predominant reaction products of the tobacco enzyme, exon 6 of the HVS gene conferred specificity for the predominant reaction products of the Hyoscyamus enzyme. Combining these two functional domains of the TEAS and HVS genes resulted in a novel enzyme capable of synthesizing reaction products reflective of both parent enzymes. The relative ratio of the TEAS and HVS reaction products was also influenced by the source of exon 5 present in the new chimeric enzymes. The association of catalytic activities with conserved but separate exonic domains suggests a general means for generating additional novel terpene cyclases.
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Affiliation(s)
- K Back
- Plant Physiology/Biochemistry/Molecular Biology Program, University of Kentucky, Lexington 40546-0091, USA
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26
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Back K, Chappell J. Cloning and bacterial expression of a sesquiterpene cyclase from Hyoscyamus muticus and its molecular comparison to related terpene cyclases. J Biol Chem 1995; 270:7375-81. [PMID: 7706281 DOI: 10.1074/jbc.270.13.7375] [Citation(s) in RCA: 136] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Genomic and cDNA clones for vetispiradiene synthase, a sesquiterpene cyclase found in Hyoscyamus muticus, were isolated using a combination of reverse transcription-polymerase chain reactions and conventional cloning procedures. RNA blot hybridization demonstrated an induction of mRNA consistent with the induction of cyclase enzyme activity in elicitor-treated cells, DNA blot hybridization indicated a gene family of 6 to 8 members, and bacterial expression of 3 cDNA clones indicated that each coded for a vetispiradiene synthase enzyme activity catalyzing the synthesis of a single reaction product. Intron-exon organization of the vetispiradiene synthase gene was identical with that previously described for 5-epi-aristolochene synthase (tobacco sesquiterpene cyclase) and casbene synthase (castor bean diterpene cyclase), and the vetispiradiene synthase amino acid sequence was 77% identical with and 81% similar to the tobacco sesquiterpene cyclase. Regions of the vetispiradiene synthase sequence centered around amino acids 60, 100, and 370 were conspicuously different relative to the tobacco sesquiterpene cyclase. The sequence similarity between the tobacco and H. muticus enzymes is suggested to be reflective of the conservation of several partial reactions common to both enzymes, and the differences may be reflective of a partial reaction unique to each enzyme.
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Affiliation(s)
- K Back
- Agronomy Department, University of Kentucky, Lexington 40546-0091, USA
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27
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Abstract
5-Epi-aristolochene synthase is a sesquiterpene cyclase activity found in pathogen-challenged tobacco cells, but not in nonchallenged tissues, and appears to be encoded by a complex gene family. As a prerequisite to assessing the functional significance of these multiple genes, bacterial expression systems were examined for their capacity to express a tobacco sesquiterpene cyclase cDNA. Insertion of full-length 5-epi-aristolochene synthase cDNA into two commonly used expression vectors, pET-11d and pGBT-T19, resulted in high level expression of the cyclase activity. The highest level of expression occurred 3 h after induction with low concentrations (0.1-0.5 mM) of IPTG, incubation at 27 degrees C instead of 37 degrees C, and in the bacterial host strain BL21(DE3). Under these conditions, the cyclase protein constituted 5 to 8% of the soluble and 35% of the total Escherichia coli proteins. Enzyme reaction products of the native tobacco and recombinant enzyme were identical, based on argentation-thin layer chromatography. Deletion mutants of the cyclase gene corresponding to the amino and carboxy termini of the enzyme were prepared. The cyclase proteins resulting from bacterial expression of these mutant constructs were found largely in the insoluble protein fraction and no soluble enzyme activity was detected.
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Affiliation(s)
- K Back
- Agronomy Department, University of Kentucky, Lexington 40546-0091
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28
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Abstract
The mental status of 27 children in divorced immigrant families and 17 children in divorced refugee families was examined, and compared to that of 113 children in divorced Swedish families. Differences in divorce-pattern between these families and Swedish divorced families were analysed. Viewed together, the immigrant and refugee children displayed a significantly higher symptom load compared to Swedish children from both divorced and intact homes. When examined separately, the refugee children but not the immigrant children were more troubled than Swedish children from divorced families. The shorter time the children had spent in Sweden, the higher was their symptom load. In comparison to Swedish divorced couples, the immigrant and refugee couples had been married for a shorter time, had been unhappy for a longer time prior to divorce, and joint custody was less common. Most of the marriages had been unhappy before the arrival in Sweden, but a dissolution had not been seen as feasible earlier. As among the Swedish couples, it was the woman who had initiated the divorce in most cases, and it was also the mother who became the residential parent in most cases.
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Affiliation(s)
- C G Svedin
- Department of Child and Adolescent Psychiatry, Faculty of Health Sciences, Linköping University, Sweden
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Abstract
A child without any prodromal events presented with incapacitating, symmetrical limb pain intensified by any movement. He lacked objective motor weakness or reflex changes. A provisional diagnosis of Guillain-Barré syndrome was not entertained despite sequential examinations that further documented dysesthesia, postural guarding, and hypertension. The clinician must consider Guillain-Barré syndrome as a cause for self-imposed immobilization associated with autonomic dysfunction.
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Affiliation(s)
- J I Singer
- Department of Emergency Medicine, Wright State University School of Medicine, Dayton, OH
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