David Businsky, MD

Effects of Acid on Bone

National Institutes of Health

Metabolic acidosis induces calcium efflux from bone and, in the process, buffers the additional hydrogen ions. Initially metabolic acidosis stimulates physicochemical mineral dissolution and subsequently cell-mediated bone resorption. Acidosis increases activity of the bone resorbing cells, the osteoclasts, and decreases activity of the bone forming cells, the osteoblasts. Osteoblastic immediate, early response genes are inhibited as are genes controlling matrix formation. Expression of the osteoclastic differentiation factor RANKL is up-regulated in osteoblasts. Both the regulation of RANKL and acid-induced calcium efflux are mediated by prostaglandins.

Mechanism of Stone Formation in the Genetic Hypercalciuric Stone-Forming Rat

National Institutes of Health

In humans, idiopathic hypercalciuria is associated with stone formation.  In order to study the mechanisms that are responsible for excess urine cacium excretion, in ways that are difficult or impossible in humans, we have developed a rat model of hypercalciuria.  Spontaneously hypercalciuric rats have been successively inbred for over 50 generations to produce a strain in which urine calcium excretion is over 10 times greater thatn that of controls, and all rats form kidney stones.  Analysis of the model has revealed that the rats not only exhibit increased intestinal calcium reabsorption but an independent defect in intestinal calcium reabsorption but an independent defect in renal tubular calcium resorption and an increased tendency for bone resorption.  These findings closely parallel those in patients with idiopathic hypercalciuria.  In the intestine, bone and kidney there is an increased number of vitamin D receptors which are hyperresponsive to 1,25-dihydroxyvitamin D3. Whether the increasednumber of vitamin D receptors is directly responsible for the hypercalciuria and whether the same abnormality is present in humans with idiopathic hypercalciuria is under investigation.  Hypercalciuric rats appear to be an excellent model to provide insights into the mechanisms causing hypercalciuria, and to delineate treatments for stone disease.

Multi-Center, Open-Label Study of the Safety and Efficacy of Fabrazyme® in Patients with Fabry Disease that previously participated in the AGAL-008 Study.

Genzyme

Fabry Disease is a glycogen storage disease which is caused by a genetic lack of the enzyme alpha-galactosidase A. These patients cannot break down certain lipids, and the lipid products accumulate intracellularly and cause, among other conditions, renal failure. The primary objective is to evaluate the stabilization of renal function with Fabrazyme® by means of estimating the difference within the placebo patients' inverse serum creatinine slope while in study AGAL-008-00 versus the inverse serum creatinine slope while in the open label extension study (AGAL02503).

Fabry Registry

Genzyme

Primary Objectives: To enhance the understanding of the variability, progression, and natural history of Fabry disease, including heterozygous females with the disease; to assist the Fabry medical community with the development of recommendations for monitoring patients and reports on patient outcomes to help optimize patient care; to characterize and describe the Fabry population as a whole; and to evaluate the long-term safety and effectiveness of Fabrazyme® .

A Multi-Center, Randomized, Open-Label Study to Compare the Efficacy and Safety of an Oral Calcimimetic Agent (AMG 073) when Two Different Vitamin Regimens are Used in Subjects with Secondary Hyperparathyroidism of End Stage Renal Disease (ESRD)

Amgen

Hyperparathyroidism occurs in patients with end-stage renal disease and leads to renal osteodystrophy. Hypocalcemia is one factor in the pathophysiology of this disease. Cinacalcet is a medication that mimics the structure of calcium and binds to the cellular calcium receptors in the parathyroid gland, causing the gland to shut off secretion of parathyroid hormone. This is a clinical trial of cinacalcet to determine if it can be used to in combination with 1,25 dihydroxy-vitamin D achieve the nationally recommended goals in treatment of hyperparathyoidism due to end-stage renal disease.

Amgen TARGET Study: Treatment Strategies to Achieve Recommended K/DOQI Goals in ESRD patients on cinacalcet

Amgen

Hyperparathyroidism occurs in patients with end-stage renal disease and leads to renal osteodystrophy. Hypocalcemia is one factor in the pathophysiology of this disease. Cinacalcet is a medication that mimics the structure of calcium and binds to the cellular calcium receptors in the parathyroid gland, causing the gland to shut off secretion of parathyroid hormone. This is a clinical trial of cinacalcet to determine if it can be used to achieve the nationally recommended goals of hyperparathyoidism therapy in patients on hemodialysis

 

Shire Protocol SPD 405-401 entitled; A Phase-IV, Open-Label, Multi-Center Trial Evaluating the Efficacy of Fosrenol® Compared to Existing Therapy in Adults with End Stage Renal Disease Treated for Hyperphosphatemia.

Shire Pharmaceutical

To assess efficacy, patient satisfaction and physician satisfaction fo Fosrenol® in adult End Stage Renal Disease (ESRD) patients requiring treatment for hyperphosphatemia in a true practice setting.

Anirban Bose, MD

The role of Perforin in Memory T Cell Generation

Perforin is a molecule similar to complement that is involved in the lysis of cells. Usually thought of as an effector molecule of CD8+ T cells, allowing them to lyse cells infected with virus or reject transplants, we have used perforing knockout mice to demonstrate that perforin is required for the generation of T cell memory. This work extends that observation and examines the role of perforin in T cell immunity.

Kevin K. Frick, PhD

Acidosis regulates prostaglandin G/H synthase-2 gene expression in bone

Renal Research Institute

We have determined that upregulation of COX-2 is essential for acid-induced bone calcium efflux. My research tests the hypothesis that COX-2 modulates the expression of pro-resorptive cytokines produced by osteoblasts. Specific goals include:
a) Determining the effects of COX-2 inhibition on the expression of pro-resorptive cytokines such as IL-1?, IL-1?, IL-6, TNF-? and RANKL and their cognate receptors, using quantitative real time polymerase chain reaction (QRT-PCR), in calvariae incubated in neutral or acidic medium.
b) Determining the effects of haploinsufficiency of COX-2 on acid modulation of cytokines and their receptors.
c) Testing the hypothesis that IL-4 inhibits acid-induced bone calcium (Ca) release by blocking acid modulation of cytokines and their receptors.

Effects of Acid on Bone

National Institutes of Health

The aim of this project is to delineate the role of the recently described G-protein coupled proton-sensing receptors (PSR), which we hypothesize constitute the initial signaling component, in the response of bone to acidosis. My specific research goals include characterizing changes in the level of intracellular Ca (Cai) and/or cAMP that occur in primary osteoblasts in response to medium simulating metabolic acidosis and to test the hypothesis that the concentration of bicarbonate ([HCO3-]) modulates the response of PSR to H+.
I am also studying alterations in gene expression induced by acidosis, in particular modulation of COX2 expression. I am identifying specific sequence elements within the COX2 promoter that are required for acid-induction of COX2 and characterizing the proteins interacting at these sites, using techniques including transient transfection, electrophoretic mobility shift, yeast one-hybrid analysis, and chromatin immunoprecipitation.

Nancy S. Krieger, PhD

Acidosis regulates prostaglandin G/H synthase-2 gene expression in bone

Renal Research Institute

This research examines the effect of acidosis on the expression of prostaglandin G/H synthase (cyclooxygenase 2), the the rate limiting enzyme responsible for synthesis of prostaglandins, in osteoblasts. In vitro studies in bone have shown that prostaglandins mediate acid-induced calcium release from bone. Understanding the mechanism of acid stimulation of prostaglandin synthesis in bone cells could provide insights into therapeutic approaches to treat or prevent the renal osteodystrophy associated with metabolic acidosis.

Effects of Acid on Bone

National Institutes of Health

My research concerns regulation of skeletal calcium homeostasis at the cellular and molecular level. Current studies address the signal transduction pathways involved in cell-mediated effects of acidosis on bone compared with calcemic hormones such as parathyroid hormone. Model systems used are neonatal mouse calvariae in organ culture as well as primary bone cells and osteoblastic osteosarcoma cell lines.

Marc Lande, MD

Cognitive function in children with hypertension

NIH/NHLBI. 1K23HL080068-01

Role: Principal Investigator

The goals of this project are to determine if children with primary hypertension experience neurocognitive deficits and if these deficits reverse with antihypertensive therapy.

Carotid ultrasound and hypertension

National Kidney Foundation (Rochester affiliate).

Role: Principal Investigator.

The goal(s) of this project are: To evaluate carotid intima-media thickness as a marker of hypertensive end-organ damage in children.

Na+/H+ Exchange in the Nematode Intestine

National Institutes of Health

Deficiencies in Na+/H+ or Cl-/HCO3- exchange compromise fluid and electrolyte transport in the mammalian intestine, but the ultimate role of acid-base transport in nutrient uptake processes and lipid metabolism is relatively poorly understood. In addition, little is known regarding how intestinal pHi influences cell signaling events that respond to nutrient availability. We hypothesis that pHi acts as a synergistic messenger, and provides a metabolic context through which the actions of diverse cellular and trans-cellular signaling pathways are interpreted. We use a physiologically simple model system, C. elegans, where the role of individual Na+/H+ exchangers in mediating intestinal function can be assessed on a genome-wide level in an intact animal. With the powerful genetic and reverse genetic tools available in C. elegans, and novel reagents for monitoring cellular pH in live nematodes, we have developed a system to study intestinal physiology and intestinal cell biology in a whole animal model.

Sai Subhodhini Reddy, MD

A Randomized Double-Blind trial of Peritoneal Dialysis Exit Site Infection Prevention Comparing Mupirocin 2% Cream to 0.1% Gentamicin Sulfate Cream.

A Multicenter study with the University of Pittsburgh and Pertoneal Dialysis Unit

Amgen Protocol 20010184 entitled: Trial to Reduce Cardiovascular Events in Patients with Chronic Kidney Disease and Diabetes Mellitus.

Amgen

This is a double-blind, placebo study using Aranesp to treat anemia in CKD, diabetic adult patients; measures cardiovascular events during treatment phase. The purpose of this research study is to evaluate what effect correction of anemia associated with chronic kidney disease using darbepoetin alfa, will have on death and cardiovascular events. These events include; cardiovascular death, heart attack, stroke, congestive heart failure , and episodes where the heart does not get enough oxygen.

A Randomized, Open-label, Study to Assess the Safty of Epoetin Alfa Manufactured by Deep Tank Technology and Epotin alfa manufactured by Roller Bottle Technology in subjects with Chronic Kidney Disease not on Dialysis.

Amgen, Inc.

This study looks at non-dialysis, CKD patients already using Epogen or Procrit for anemia, evaluating a new manufacturing method.

George J. Schwartz, MD

Renal Tubular Acid-Base Regulation

National Institutes of Health

The kidney maintains acid base homeostasis and failure to excrete acid results in renal tubular acidosis, a major cause of failure to thrive and kidney stones in children. We have developed an in vitro model of acidosis that recapitulates the in vivo situation in the collecting duct of the kidney. Recent studies show that during acidosis a novel protein, hensin, is secreted into the extracellular matrix of the acid-secreting intercalated cells of the kidney and this process is critical to renal acidification. Hensin must bind to a receptor on the surface of uncommitted intercalated cells and somehow instruct the cells to adapt by expressing proton pumps on their apical membranes and anion exchangers on their basolateral membranes, so as to increase urinary acid excretion. The plan is to now examine the localization, regulation and role of the hensin receptor, as well as intracellular transducers and other proteins, under normal, acidotic, and alkalotic conditions. We are also using pH sensitive fluorescent dyes to examine in individually identified cells whether and how intercalated cells change their functional polarity from a quiescent or bicarbonate secreting cell to a robust acid excreting cell during exposure to in vitro acidosis. Since the drug, Cyclosporin A, commonly used as an immunosuppressive agent, can also cause renal tubular acidosis, our laboratory is investigating the mechanism by which this occurs. Preliminary studies suggest that cyclosporin somehow prevents the polymerization of hensin around intercalated cells resulting in decreased acid secretion and acidosis. This is currently being investigated in our laboratory.

Ongoing Research Support

Renal Adaptation to Metabolic Acidosis

American Heart Association
Northeast Affiliate Grant-in-Aid
0455829T Schwartz (PI) 07/01/04-06/30/07

The major goals of this project are to examine the matrix protein hensin which is polymerized around adapting b-intercalated cells and controls their adaptive response to acidosis. The roles of integrins, galectin-3, and cyclophilins will be investigated in this adaptation to acidosis. Another aim investigates the role of nitric oxide production in the regulation of HCO3- transport in the CCD.
Role: PI

NOTE: THIS GRANT WILL BE RELINQUISHED IF THE NIH APPLICATION IS FUNDED. IT IS ALTERNATIVE.

Kidney Disease in Children Data Management and Analysis Cooperative Agreement

National Institutes of Health

The major goal of this project is to serve as the Data Management and Analysis Center for the two NIH-supported Clinical Centers conducting the Prospective Study of Chronic Kidney Disease in Children. G.J.S. is the PI of the Central Lab subcontract at the University of Rochester and is in charge of conceiving protocols and calculations for measuring GFR in children, designing the sample kits to be sent to study patients across the USA, assuring quality control of the results, and supervising communication with the Clinical Centers and exchange of data with the Data Coordinating Center.
Role: PI of University of Rochester subcontract

Completed Research Support

Resistance of Renal H + Secretion to Carbonic Anhydrase Inhibition during Metabolic Acidosis

Maren Foundation 3/1/01-2/28/03

The major goal of this study is to answer whether the kidney resistance is due to altered sensitivity of proton pumps to carbonic anhydrase inhibition or to altered sensitivity of these proton pumps to the acid gradients developing in the adapting kidney.
Role: PI

Adaptation of B-Intercalated Cells to Metabolic Acidosis

American Heart Association Grant-in-Aid 01/10/01-12/31/03

The major goals of this project are to investigate the mechanisms by which B-Intercalated cells down-regulate bicarbonate secretion with response to metabolic acidosis.

Bicarbonate Transport by the Maturing Renal Tubule

National Institutes of Health

R01 DK 50603 7/1/00-6/30/04

Martin S. Zand, MD, PhD (Zand Laboratory Web Page)

Rochester Center for Biodefense Immune Modeling

National Institutes of Health (NIH/NIAID N01-AI-50020)

Immune responses to influenza and orthopox viruses depend on the kinetics of B and T cell responses after activation. This 5 year project is designed to create and test computational models of immune responses to natural and modified influenza and orthopox viruses. My laboratory has two sub-projects in this center grant: (1) to experimentally derive parameters used to model B cell activation, maturation, and antibody secretion to vaccines and viral infection and (2) to develop a multicompartment stochastic discrete event model of human immune responses.

Immune Function and Biodefense in Children,
Elderly, and Immunocompromised Populations

National Institutes of Health (NIH/NIAID N01-AI-50029)

Children, the elderly and immunocompromised patients may have altered immune responses to viral and bacterial pathogens. As such, these individuals may be the first to be infected by bioterror agents, and the most susceptable to serious consequences of infection. In this project, my laboratory is working to create discrete event stochastic models of B and T cell immune responses of patients who have been treated with anti-TNF therapies.

Discrete event computer simulation of B cell mediated kidney transplant rejection

Alternatives Research and Development Foundation

Humoral rejection of kidney transplants is mediated by host B cells that produce antibodies directed against HLA antigens expressed on the transplanted kidney. In this project, we are using an in vitro system for plasma cell differentiation to generate data concerning the kinetics of B cell activation and differentiation, and how various immunosuppressive medications influence this process. We are then using this data to populate a multi-compartment, stochastic, discrete event computer model. The goal of this work is to use such models to better predict the effects of such medications without the use of animal animal experimentation.

Is Rapamune (sirolimus) Permissive for Compensatory Renal Allograft Hypertrophy? A Prospective, Randomized, Controlled Study of Compensatory Renal Hypertrophy in Renal Allograft Recipients and their Living Donors

Wyeth-Ayerst

We know that after uninephrectomy the remaining kidney increases in size and hyperfiltrates to the point where the glomerular filtration rate returns to approximately 60-70% of the pre-nephrectomy level, but with only the one kidney. This does not, however, occur in the transplant recipient. We hypothesize that this absence of physiologic compensation is due to the use of calcinerin inhibitor immunosuppression, such as cyclosporine or tacrolimus. Sirolimus, a TOR inhibitor immunosuppression agent, may permit compensatory renal hypertophy. This study is a randomized, prospective trial of sirolimus versus tacrolimus at 3 months post-transplant. Both donor and recipient creatinine clearance will be measured and we will assess how close the recipient renal function comes to the donors on either therapy.