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221 Expression, Distribution, and Cellular Localization of the Novel Plasminogen Receptor, PLG-RKT, in Murine Kidney
NKF 2011 Spring Clinical Meetings Abstracts
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EXPRESSION, DISTRIBUTION, AND CELLULAR LOCALIZATION OF THE NOVEL PLASMINOGEN RECEPTOR, PLG-RKT, IN MURINE KIDNEY Samir Nangia1, Hongdong Bai1, William B. Kiosses2, Volker Vallon1, Lindsey A. Miles2, and Robert J. Parmer1. 1University of California, San Diego, and VA San Diego Healthcare System; 2The Scripps Research Institute, La Jolla, CA, USA Recent work suggests a key role for the plasminogen activation system in the proteolytic processing and activation of the epithelial sodium channel (ENaC), providing an important mechanism for the sodium retention associated with nephrotic syndrome, in which increased plasminogen concentrations are present in urine. We recently identified a novel transmembrane plasminogen receptor, PLG-RKT, which markedly enhances cell surface activation of plasminogen to the active protease plasmin. We also recently demonstrated that PLG-RKT is expressed as a membrane component in renal epithelial cell lines. Here, we investigated the expression, distribution, and cellular localization of PLG-RKT in murine kidney. C57Bl6 mice were perfused in situ with 4% paraformaldehyde. Kidneys were dissected, removed, and fixed in 4% paraformaldehyde, placed through a sucrose gradient and then frozen in OCT medium. Sections (10 µM thick) were immunostained with antisera specific for PLG-RKT, as well as the urokinase receptor (uPAR, another key component of the plasminogen activation pathway), and γENaC, followed by fluorescent labeled secondary antibody, and examined using high resolution laser scanning confocal microscopy. PLG-RKT was prominently expressed in proximal and distal nephron segments, particularly in the distal tubule and collecting duct. PLG-RKT was observed primarily on the apical surface, with some labeling also in a punctate distribution in the cytoplasm, in a pattern that was similar to that observed for γENaC. uPAR (a GPI-linked membrane protein) was primarily observed in the distal nephron, and was almost exclusively on the apical surface. PLGRKT, uPAR, and ENaC, all co-localized at the apical surface in the distal nephron. These results demonstrate that PLG-RKT, uPAR, and ENaC are co-localized on the apical surface in the distal nephron in vivo, and are present in an orientation to promote plasminogen activation and ENaC processing.
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SEVERE HYPOCALCEMIA IN A HEMODIALYSIS PATIENT WITH TERTIARY HYPERPARATHYROIDISM Samir Nangia, Scott Mullaney University of California, San Diego, California, USA Spontaneous parathyroid autoinfarction has been described in primary hyperparathyroidism and in extremely rare cases of secondary hyperparathyroidism in dialysis patients. The mechanism of action has yet to be determined; however previous case reports demonstrate marked falls in serum calcium and PTH values. We present a unique case of life threatening hypocalcemia from spontaneous parathyroid autoinfarction in a patient with tertiary hyperparathyroidism. A 46 year old male with history of ESRD on hemodialysis and tertiary hyperparathyroidism was admitted for new onset seizure along with perioral numbness and tingling. He also presented with recent onset of left sided neck pain with tender 2x2 cm mass on exam. Prior to admission patient had elevated PTH and serum calcium despite lack of vitamin D administration supporting the diagnosis of tertiary hyperparathyroidism. On admission patient was noted to have serum calcium of 5.1 mEq/dL and ionized calcium of 0.48 mmol/L. His labs also demonstrated an abrupt drop in PTH from 1770 pg/ml to108 pg/ml within one month. Patient’s symptoms resolved after being treated with intravenous calcium gluconate, calcitriol, and increased calcium in dialysis bath. His hypocalcemia was felt to be secondary to infarction of his dominant parathyroid gland as evidenced by the new tender left sided neck mass. The remaining 3 parathyroid glands recovered post hospitalization and became hyperfunctional creating a secondary hyperparathyroidism with an elevated PTH, elevated phosphorus, and decreased alkaline phosphatase confirming resolution of hungry bone syndrome. To our knowledge this is the first documented case of autoinfarction in a dialysis patient with tertiary hyperparathyroidism leading to acute severe hypocalcemia. Date Pre-hospitalizaon Hospitalizaon Post-hospitalizaon
A72
PHYSICIAN DRIVEN VISUAL TRACKING SYSTEM IMPROVES PHOSPHORUS CONTROL IN DIALYSIS PATIENTS Parineesha Nath, Swa Arora, Janice Nigos, Tina Ko, Kalathil Sureshkumar, Richard Marcus, Barbara Clark, Allegheny General Hospital, Pisburgh, PA, USA. Hyperphosphatemia is associated with increased morbidity and mortality in ESRD paents but it remains challenging to achieve levels within the acceptable range. Repeated educaon and movaonal tools may help. We studied the impact of a physician-driven visual tracking system (VTS) on phosphorus control in 62 paents on chronic hemodialysis with hyperphosphatemia (phosphorus>5). For a period of three months, we implemented a VTS that represented phosphorus levels on an analog scale with visual cartoon symbols depicng “good and bad” levels, followed by a detailed review of potenal complicaons, paent’s diet and use of phosphorus binders by a physician on a one to one basis. Calcium, phosphorus, albumin and parathyroid hormone (PTH) levels were collected before and aer the intervenon. Paired t-test was used for stascal analysis. Mean P levels fell from 6.55+ 0.16 to 5.93+ 0.18 (pre vs post VTS, p-value of 0.0002), and mean PTH levels fell from 382.7+ 34.5 and 319.7+ 26.2, respecvely (p-value = 0.02). There was no significant difference between albumin or calcium levels before and aer the intervenon. 74% of paents were on calcium based phosphate binders, 40% were on non-calcium based binders, 91% were on Vitamin D analogues and 21% were on calcimimecs. We conclude that the use of an aenon grabbing, easy to understand visual tracking system, when implemented on a one to one basis by the physicians, helps in improving phosphorus control in ESRD.
PTH (pg/ml) 1770 108 927
Serum Calcium (mEq/dL) 11.5 5.1 9.2
Serum Phosphorus (mEq/dL) 7.3 3.7 5.3
Ionized Calcium (mmol/L) 1.29 0.48 1.12
ALP (U/L) 471 1024 105
INCIDENCE OF MALIGANCY AFTER KIDNEY TRANSPLANTATION WITH ALEMTUZUMAB AND OTHER INDUCTION AGENTS Manish Nepal, Ammar Al-laham, Craig Wood and Rajesh Govindasamy. Geisinger Medical Center, Danville, PA Alemtuzumab is a commonly used induction agent for kidney transplantation. It’s getting more popular due to allowance of recipients to be on a steroid-free regimen and low-dose maintenance immunosuppression therapy. The objective of this study is to identify and compare the incidence and outcome of malignancy using alemtuzumab induction and other induction protocols. Using Organ procurement and Transplantation Network (OPTN database) we evaluated total of 110,903 kidney transplant recipients whom were transplanted from 2003 Jan 1 to Dec 31 2009 nationwide. 10,437 patients received Alemtuzumab induction and 110,903 received other form of induction agent. We used Chi-square test to study difference in proportion, two-sample t-test for difference in mean between two groups, Kaplan Meier analysis for survival and malignancy estimates and cox model hazard ratio for malignancy and graft failure rates in adjusted and non-adjusted models. The mean follow up period was of 3.5 +/-2.5 years. Mean age (SD) was 48.7+/-14.7[<1, 87] in Alemtuzumab group vs 47.6+/-15.9[<1, 96] in non-alemtuzumab group. 4% had reported malignancy in both groups in the past. 60% were male, and were ethnically diverse (55% White, 24% Black, 15% Hispanic, and 5% Asian). Kaplan-Meier estimates for 1-year, 3-year and 5-year malignancy rates were 1.3%, 3.9%, and 6.9%, overall death rates were 2.8%, 7.6%, and 13.5%, and graft failure rates were 6.6%, 15.5%, and 25.4%, respectively. Skin cancer (squamous and basal) were the highest reported malignancy (1570) followed by PTLD (506), lung (271) prostate (230) and renal cancer (220). There was no difference in distribution of tumor type between alemtuzumab group (N=326 with a post transplant tumor) and those with other induction agent (N=4025 with a post transplant tumor) (chi-square p-value = 0.48). When using Cox regression to adjust for age, gender, ethnicity, and prior malignancy, alemtuzumab use was associated with lower malignancies (HR=0.84, 95% CI= [0.75, 0.94], p=0.003) and higher graft failure rate (HR=1.09, 95% CI= [1.04, 1.15], p=0.0004). Alemtuzumab use was not associated with high death rate (HR=1.06, 95% CI=[0.99, 1.14], p=0.11). In conclusion, Alemtuzumab induction protocol clearly has an advantage of lower incidence of post transplant malignancies. (Above information is based on OPTN data as on Sep 10, 2010. website: http://optn.transplant.hrsa.gov )
Am J Kidney Dis. 2011;57(4):A1-A108
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EXPRESSION, DISTRIBUTION, AND CELLULAR LOCALIZATION OF THE NOVEL PLASMINOGEN RECEPTOR, PLG-RKT, IN MURINE KIDNEY Samir Nangia1, Hongdong Bai1, William B. Kiosses2, Volker Vallon1, Lindsey A. Miles2, and Robert J. Parmer1. 1University of California, San Diego, and VA San Diego Healthcare System; 2The Scripps Research Institute, La Jolla, CA, USA Recent work suggests a key role for the plasminogen activation system in the proteolytic processing and activation of the epithelial sodium channel (ENaC), providing an important mechanism for the sodium retention associated with nephrotic syndrome, in which increased plasminogen concentrations are present in urine. We recently identified a novel transmembrane plasminogen receptor, PLG-RKT, which markedly enhances cell surface activation of plasminogen to the active protease plasmin. We also recently demonstrated that PLG-RKT is expressed as a membrane component in renal epithelial cell lines. Here, we investigated the expression, distribution, and cellular localization of PLG-RKT in murine kidney. C57Bl6 mice were perfused in situ with 4% paraformaldehyde. Kidneys were dissected, removed, and fixed in 4% paraformaldehyde, placed through a sucrose gradient and then frozen in OCT medium. Sections (10 µM thick) were immunostained with antisera specific for PLG-RKT, as well as the urokinase receptor (uPAR, another key component of the plasminogen activation pathway), and γENaC, followed by fluorescent labeled secondary antibody, and examined using high resolution laser scanning confocal microscopy. PLG-RKT was prominently expressed in proximal and distal nephron segments, particularly in the distal tubule and collecting duct. PLG-RKT was observed primarily on the apical surface, with some labeling also in a punctate distribution in the cytoplasm, in a pattern that was similar to that observed for γENaC. uPAR (a GPI-linked membrane protein) was primarily observed in the distal nephron, and was almost exclusively on the apical surface. PLGRKT, uPAR, and ENaC, all co-localized at the apical surface in the distal nephron. These results demonstrate that PLG-RKT, uPAR, and ENaC are co-localized on the apical surface in the distal nephron in vivo, and are present in an orientation to promote plasminogen activation and ENaC processing.
222
224
SEVERE HYPOCALCEMIA IN A HEMODIALYSIS PATIENT WITH TERTIARY HYPERPARATHYROIDISM Samir Nangia, Scott Mullaney University of California, San Diego, California, USA Spontaneous parathyroid autoinfarction has been described in primary hyperparathyroidism and in extremely rare cases of secondary hyperparathyroidism in dialysis patients. The mechanism of action has yet to be determined; however previous case reports demonstrate marked falls in serum calcium and PTH values. We present a unique case of life threatening hypocalcemia from spontaneous parathyroid autoinfarction in a patient with tertiary hyperparathyroidism. A 46 year old male with history of ESRD on hemodialysis and tertiary hyperparathyroidism was admitted for new onset seizure along with perioral numbness and tingling. He also presented with recent onset of left sided neck pain with tender 2x2 cm mass on exam. Prior to admission patient had elevated PTH and serum calcium despite lack of vitamin D administration supporting the diagnosis of tertiary hyperparathyroidism. On admission patient was noted to have serum calcium of 5.1 mEq/dL and ionized calcium of 0.48 mmol/L. His labs also demonstrated an abrupt drop in PTH from 1770 pg/ml to108 pg/ml within one month. Patient’s symptoms resolved after being treated with intravenous calcium gluconate, calcitriol, and increased calcium in dialysis bath. His hypocalcemia was felt to be secondary to infarction of his dominant parathyroid gland as evidenced by the new tender left sided neck mass. The remaining 3 parathyroid glands recovered post hospitalization and became hyperfunctional creating a secondary hyperparathyroidism with an elevated PTH, elevated phosphorus, and decreased alkaline phosphatase confirming resolution of hungry bone syndrome. To our knowledge this is the first documented case of autoinfarction in a dialysis patient with tertiary hyperparathyroidism leading to acute severe hypocalcemia. Date Pre-hospitalizaon Hospitalizaon Post-hospitalizaon
A72
PHYSICIAN DRIVEN VISUAL TRACKING SYSTEM IMPROVES PHOSPHORUS CONTROL IN DIALYSIS PATIENTS Parineesha Nath, Swa Arora, Janice Nigos, Tina Ko, Kalathil Sureshkumar, Richard Marcus, Barbara Clark, Allegheny General Hospital, Pisburgh, PA, USA. Hyperphosphatemia is associated with increased morbidity and mortality in ESRD paents but it remains challenging to achieve levels within the acceptable range. Repeated educaon and movaonal tools may help. We studied the impact of a physician-driven visual tracking system (VTS) on phosphorus control in 62 paents on chronic hemodialysis with hyperphosphatemia (phosphorus>5). For a period of three months, we implemented a VTS that represented phosphorus levels on an analog scale with visual cartoon symbols depicng “good and bad” levels, followed by a detailed review of potenal complicaons, paent’s diet and use of phosphorus binders by a physician on a one to one basis. Calcium, phosphorus, albumin and parathyroid hormone (PTH) levels were collected before and aer the intervenon. Paired t-test was used for stascal analysis. Mean P levels fell from 6.55+ 0.16 to 5.93+ 0.18 (pre vs post VTS, p-value of 0.0002), and mean PTH levels fell from 382.7+ 34.5 and 319.7+ 26.2, respecvely (p-value = 0.02). There was no significant difference between albumin or calcium levels before and aer the intervenon. 74% of paents were on calcium based phosphate binders, 40% were on non-calcium based binders, 91% were on Vitamin D analogues and 21% were on calcimimecs. We conclude that the use of an aenon grabbing, easy to understand visual tracking system, when implemented on a one to one basis by the physicians, helps in improving phosphorus control in ESRD.
PTH (pg/ml) 1770 108 927
Serum Calcium (mEq/dL) 11.5 5.1 9.2
Serum Phosphorus (mEq/dL) 7.3 3.7 5.3
Ionized Calcium (mmol/L) 1.29 0.48 1.12
ALP (U/L) 471 1024 105
INCIDENCE OF MALIGANCY AFTER KIDNEY TRANSPLANTATION WITH ALEMTUZUMAB AND OTHER INDUCTION AGENTS Manish Nepal, Ammar Al-laham, Craig Wood and Rajesh Govindasamy. Geisinger Medical Center, Danville, PA Alemtuzumab is a commonly used induction agent for kidney transplantation. It’s getting more popular due to allowance of recipients to be on a steroid-free regimen and low-dose maintenance immunosuppression therapy. The objective of this study is to identify and compare the incidence and outcome of malignancy using alemtuzumab induction and other induction protocols. Using Organ procurement and Transplantation Network (OPTN database) we evaluated total of 110,903 kidney transplant recipients whom were transplanted from 2003 Jan 1 to Dec 31 2009 nationwide. 10,437 patients received Alemtuzumab induction and 110,903 received other form of induction agent. We used Chi-square test to study difference in proportion, two-sample t-test for difference in mean between two groups, Kaplan Meier analysis for survival and malignancy estimates and cox model hazard ratio for malignancy and graft failure rates in adjusted and non-adjusted models. The mean follow up period was of 3.5 +/-2.5 years. Mean age (SD) was 48.7+/-14.7[<1, 87] in Alemtuzumab group vs 47.6+/-15.9[<1, 96] in non-alemtuzumab group. 4% had reported malignancy in both groups in the past. 60% were male, and were ethnically diverse (55% White, 24% Black, 15% Hispanic, and 5% Asian). Kaplan-Meier estimates for 1-year, 3-year and 5-year malignancy rates were 1.3%, 3.9%, and 6.9%, overall death rates were 2.8%, 7.6%, and 13.5%, and graft failure rates were 6.6%, 15.5%, and 25.4%, respectively. Skin cancer (squamous and basal) were the highest reported malignancy (1570) followed by PTLD (506), lung (271) prostate (230) and renal cancer (220). There was no difference in distribution of tumor type between alemtuzumab group (N=326 with a post transplant tumor) and those with other induction agent (N=4025 with a post transplant tumor) (chi-square p-value = 0.48). When using Cox regression to adjust for age, gender, ethnicity, and prior malignancy, alemtuzumab use was associated with lower malignancies (HR=0.84, 95% CI= [0.75, 0.94], p=0.003) and higher graft failure rate (HR=1.09, 95% CI= [1.04, 1.15], p=0.0004). Alemtuzumab use was not associated with high death rate (HR=1.06, 95% CI=[0.99, 1.14], p=0.11). In conclusion, Alemtuzumab induction protocol clearly has an advantage of lower incidence of post transplant malignancies. (Above information is based on OPTN data as on Sep 10, 2010. website: http://optn.transplant.hrsa.gov )
Am J Kidney Dis. 2011;57(4):A1-A108