Medicine and Health Sciences Commons^™

Mechanotransduction Signaling In Podocytes From Fluid Flow Shear Stress., Tarak Srivastava, Hongying Dai, Daniel P. Heruth, Uri S. Alon, Robert E. Garola, Jianping Zhou, R Scott Duncan, Ashraf El-Meanawy, Ellen T. Mccarthy, Ram Sharma, Mark L. Johnson, Virginia J. Savin, Mukut Sharma

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Recently, we and others have found that hyperfiltration-associated increase in biomechanical forces, namely, tensile stress and fluid flow shear stress (FFSS), can directly and distinctly alter podocyte structure and function. The ultrafiltrate flow over the major processes and cell body generates FFSS to podocytes. Our previous work suggests that the cyclooxygenase-2 (COX-2)-PGE2-PGE2 receptor 2 (EP2) axis plays an important role in mechanoperception of FFSS in podocytes. To address mechanotransduction of the perceived stimulus through EP2, cultured podocytes were exposed to FFSS (2 dyn/cm2) for 2 h. Total RNA from cells at the end of FFSS treatment, 2-h post-FFSS, and 24-h …

Effect Of Hemiepiphysiodesis On The Growth Plate: The Histopathological Changes And Mechanism Exploration Of Recurrence In Mini Pig Model., Jing Ding, Jin He, Zhi-Qiang Zhang, Zhen-Kai Wu, Fang-Chun Jin

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Purpose: Hemiepiphysiodesis has been widely used to correct angular deformity of long bone in immature patients. However, there is a limited knowledge about the biomechanical effect of this technique on the histopathological changes of the growth plate and the mechanism of recurrence of malformation after implant removal. We aimed to evaluate the biomechanical effect of hemiepiphysiodesis on the histopathological changes of the growth plate and the mechanism of recurrence of malformation after implant removal in Bama miniature pigs, and to explore the role of asymmetric stress during this procedure.

Methods: Eight 3-month-old male Bama miniature pigs sustained surgeries on the …

Hyperfiltration-Associated Biomechanical Forces In Glomerular Injury And Response: Potential Role For Eicosanoids., Mukut Sharma, Ram Sharma, Ellen T. Mccarthy, Virginia J. Savin, Tarak Srivastava

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Hyperfiltration is a well-known risk factor in progressive loss of renal function in chronic kidney disease (CKD) secondary to various diseases. A reduced number of functional nephrons due to congenital or acquired cause(s) results in hyperfiltration in the remnant kidney. Hyperfiltration-associated increase in biomechanical forces, namely pressure-induced tensile stress and fluid flow-induced shear stress (FFSS) determine cellular injury and response. We believe the current treatment of CKD yields limited success because it largely attenuates pressure-induced tensile stress changes but not the effect of FFSS on podocytes. Studies on glomerular podocytes, tubular epithelial cells and bone osteocytes provide evidence for a …

Role Of Biomechanical Forces In Hyperfiltration-Mediated Glomerular Injury In Congenital Anomalies Of The Kidney And Urinary Tract., Tarak Srivastava, Ganesh Thiagarajan, Uri S. Alon, Ram Sharma, Ashraf El-Meanawy, Ellen T. Mccarthy, Virginia J. Savin, Mukut Sharma

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Congenital anomalies of the kidney and urinary tract (CAKUT) including solitary kidney constitute the main cause of progressive chronic kidney disease (CKD) in children. Children born with CAKUT develop signs of CKD only during adolescence and do not respond to renin-angiotensin-aldosterone system blockers. Early cellular changes underlying CKD progression to end-stage renal disease by early adulthood are not well understood. The mechanism of maladaptive hyperfiltration that occurs from loss of functional nephrons, including solitary kidney, is not clear. We re-examine the phenomenon of hyperfiltration in the context of biomechanical forces with special reference to glomerular podocytes. Capillary stretch exerts tensile …

Multiple Targets For Novel Therapy Of Fsgs Associated With Circulating Permeability Factor., Virginia J. Savin, Mukut Sharma, Jianping Zhou, David Genochi, Ram Sharma, Tarak Srivastava, Amna Ilahe, Pooja Budhiraja, Aditi Gupta, Ellen T. Mccarthy

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A plasma component is responsible for altered glomerular permeability in patients with focal segmental glomerulosclerosis. Evidence includes recurrence after renal transplantation, remission after plasmapheresis, proteinuria in infants of affected mothers, transfer of proteinuria to experimental animals, and impaired glomerular permeability after exposure to patient plasma. Therapy may include decreasing synthesis of the injurious agent, removing or blocking its interaction with cells, or blocking signaling or enhancing cell defenses to restore the permeability barrier and prevent progression. Agents that may prevent the synthesis of the permeability factor include cytotoxic agents or aggressive chemotherapy. Extracorporeal therapies include plasmapheresis, immunoadsorption with protein A …

Nicotinamide Adenine Dinucleotide Phosphate Oxidase 2 Regulates Lps-Induced Inflammation And Alveolar Remodeling In The Developing Lung., Heather Menden, Sheng Xia, Sherry M. Mabry, Angels Navarro, Michael F. Nyp, Venkatesh Sampath

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In premature infants, sepsis is associated with alveolar simplification manifesting as bronchopulmonary dysplasia. The redox-dependent mechanisms underlying sepsis-induced inflammation and alveolar remodeling in the immature lung remain unclear. We developed a neonatal mouse model of sepsis-induced lung injury to investigate whether nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) regulates Toll-like receptor (TLR)-mediated inflammation and alveolar remodeling. Six-day-old NOX2

Cyclooxygenase-2, Prostaglandin E2, And Prostanoid Receptor Ep2 In Fluid Flow Shear Stress-Mediated Injury In The Solitary Kidney., Tarak Srivastava, Uri S. Alon, Patricia A. Cudmore, Belal Tarakji, Alexander Kats, Robert E. Garola, R Scott Duncan, Ellen T. Mccarthy, Ram Sharma, Mark L. Johnson, Lynda F. Bonewald, Ashraf El-Meanawy, Virginia J. Savin, Mukut Sharma

Manuscripts, Articles, Book Chapters and Other Papers

Hyperfiltration subjects podocytes to increased tensile stress and fluid flow shear stress (FFSS). We showed a 1.5- to 2.0-fold increase in FFSS in uninephrectomized animals and altered podocyte actin cytoskeleton and increased synthesis of prostaglandin E2 (PGE2) following in vitro application of FFSS. We hypothesized that increased FFSS mediates cellular changes through specific receptors of PGE2. Presently, we studied the effect of FFSS on cultured podocytes and decapsulated isolated glomeruli in vitro, and on solitary kidney in uninephrectomized sv129 mice. In cultured podocytes, FFSS resulted in increased gene and protein expression of cyclooxygenase (COX)-2 but not COX-1, prostanoid receptor EP2 …

Fluid Flow Shear Stress Over Podocytes Is Increased In The Solitary Kidney., Tarak Srivastava, Gianni E. Celsi, Mukut Sharma, Hongying Dai, Ellen T. Mccarthy, Melanie Ruiz, Patricia A. Cudmore, Uri S. Alon, Ram Sharma, Virginia A. Savin

Manuscripts, Articles, Book Chapters and Other Papers

BACKGROUND: Glomerular hyperfiltration is emerging as the key risk factor for progression of chronic kidney disease (CKD). Podocytes are exposed to fluid flow shear stress (FFSS) caused by the flow of ultrafiltrate within Bowman's space. The mechanism of hyperfiltration-induced podocyte injury is not clear. We postulated that glomerular hyperfiltration in solitary kidney increases FFSS over podocytes.

METHODS: Infant Sprague-Dawley rats at 5 days of age and C57BL/6J 14-week-old adult mice underwent unilateral nephrectomy. Micropuncture and morphological studies were then performed on 20- and 60-day-old rats. FFSS over podocytes in uninephrectomized rats and mice was calculated using the recently published equation …