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1.  Systems Biology Investigation of cAMP Modulation to Increase SMN Levels for the Treatment of Spinal Muscular Atrophy 
PLoS ONE  2014;9(12):e115473.
Spinal muscular atrophy (SMA), a leading genetic cause of infant death worldwide, is an autosomal recessive disorder caused by the loss of SMN1 (survival motor neuron 1), which encodes the protein SMN. The loss of SMN1 causes a deficiency in SMN protein levels leading to motor neuron cell death in the anterior horn of the spinal cord. SMN2, however, can also produce some functional SMN to partially compensate for loss of SMN1 in SMA suggesting increasing transcription of SMN2 as a potential therapy to treat patients with SMA. A cAMP response element was identified on the SMN2 promoter, implicating cAMP activation as a step in the transcription of SMN2. Therefore, we investigated the effects of modulating the cAMP signaling cascade on SMN production in vitro and in silico. SMA patient fibroblasts were treated with the cAMP signaling modulators rolipram, salbutamol, dbcAMP, epinephrine and forskolin. All of the modulators tested were able to increase gem formation, a marker for SMN protein in the nucleus, in a dose-dependent manner. We then derived two possible mathematical models simulating the regulation of SMN2 expression by cAMP signaling. Both models fit well with our experimental data. In silico treatment of SMA fibroblasts simultaneously with two different cAMP modulators resulted in an additive increase in gem formation. This study shows how a systems biology approach can be used to develop potential therapeutic targets for treating SMA.
PMCID: PMC4267815  PMID: 25514431
2.  Development of Physiologically Based Pharmacokinetic Model (PBPK) of BMP2 in Mice 
Bone Morphogenetic protein 2 holds great promise for potential applications in the clinic. It is a potent growth factor for the use in the cervical spine surgery (FDA approved 2002) and has been marketed as “Infuse” for treating open tibial shaft fractures (FDA approved 2004). However, its use is limited by several significant side effects that maybe due to its potency and effect on different stem cell populations in the spine. BMP2 is expressed throughout the human body in several tissues and at a very high concentration in the blood. BMP receptors, especially BMP receptor type Ia, is ubiquitously expressed in most tissues. Currently, it is difficult to determine how BMP2 is physiologically distributed in mice or humans and no quantitative models are available.
A Physiologically-Based Pharmaco-Kinetic (PBPK) model has been developed to determine steady-state distribution of BMP2 in mice. The multi-compartmental PBPK model represents relevant organ/tissues with physiological accuracy. The organs/tissue compartments chosen were brain, lung, heart, liver, pancreas, kidney, uterus, bone and fat. A blood compartment maintained connectivity among the various organs. Four processes characterized the change in the concentration of the protein in every compartment: blood flow in, blood flow out, protein turnover and receptor binding in the organ. The unique aspects of the model are the determination of elimination using receptor kinetics and generation using protein turnover. The model also predicts steady state concentrations of BMP2 in tissues in mice and may be used for possible scale-up of dosage regimens in humans.
PMCID: PMC4254668  PMID: 25485286
BMP2; PBPK; BMP2 receptor; BMP2 distribution; Systems biology; BMP2 steady state concentrations
3.  Maximum Recommended Dosage of Lithium for Pregnant Women Based on a PBPK Model for Lithium Absorption 
Advances in Bioinformatics  2012;2012:352729.
Treatment of bipolar disorder with lithium therapy during pregnancy is a medical challenge. Bipolar disorder is more prevalent in women and its onset is often concurrent with peak reproductive age. Treatment typically involves administration of the element lithium, which has been classified as a class D drug (legal to use during pregnancy, but may cause birth defects) and is one of only thirty known teratogenic drugs. There is no clear recommendation in the literature on the maximum acceptable dosage regimen for pregnant, bipolar women. We recommend a maximum dosage regimen based on a physiologically based pharmacokinetic (PBPK) model. The model simulates the concentration of lithium in the organs and tissues of a pregnant woman and her fetus. First, we modeled time-dependent lithium concentration profiles resulting from lithium therapy known to have caused birth defects. Next, we identified maximum and average fetal lithium concentrations during treatment. Then, we developed a lithium therapy regimen to maximize the concentration of lithium in the mother's brain, while maintaining the fetal concentration low enough to reduce the risk of birth defects. This maximum dosage regimen suggested by the model was 400 mg lithium three times per day.
PMCID: PMC3369391  PMID: 22693500
4.  A Transformative Model for Undergraduate Quantitative Biology Education 
CBE Life Sciences Education  2010;9(3):181-188.
The BIO2010 report recommended that students in the life sciences receive a more rigorous education in mathematics and physical sciences. The University of Delaware approached this problem by (1) developing a bio-calculus section of a standard calculus course, (2) embedding quantitative activities into existing biology courses, and (3) creating a new interdisciplinary major, quantitative biology, designed for students interested in solving complex biological problems using advanced mathematical approaches. To develop the bio-calculus sections, the Department of Mathematical Sciences revised its three-semester calculus sequence to include differential equations in the first semester and, rather than using examples traditionally drawn from application domains that are most relevant to engineers, drew models and examples heavily from the life sciences. The curriculum of the B.S. degree in Quantitative Biology was designed to provide students with a solid foundation in biology, chemistry, and mathematics, with an emphasis on preparation for research careers in life sciences. Students in the program take core courses from biology, chemistry, and physics, though mathematics, as the cornerstone of all quantitative sciences, is given particular prominence. Seminars and a capstone course stress how the interplay of mathematics and biology can be used to explain complex biological systems. To initiate these academic changes required the identification of barriers and the implementation of solutions.
PMCID: PMC2931664  PMID: 20810949
5.  A suspected case of carbimazole-associated torsades de pointes 
Indian Journal of Pharmacology  2010;42(1):53-54.
Torsades de pointes (TdP) or polymorphic ventricular tachycardia owing to drug-induced QT prolongation is a common cause of withdrawal of marketed drugs and has caused increasing concern in the recent past. Carbimazole, the common antithyroid drug, is not a very well-known offender to cause QT prolongation and TdP. Only a few cases of carbimazole-induced TdP have been reported so far. We report a 53-year-old woman who was on tab. carbimazole (10 mg) twice daily for one month and who presented with respiratory distress, palpitation and syncope attack. Her surface electrocardiogram (ECG) was showing the evidence of TdP and subsequently hypokalemia was also detected. She received conservative management including potassium supplementation. However, QT prolongation persisted even after normalization of serum potassium level. Carbimazole was withdrawn and the patient was discharged as she remained stable and symptom free. This study highlights a possible association between carbimazole and TdP.
PMCID: PMC2885642  PMID: 20606839
Carbimazole; QT prolongation; torsades de pointes

Results 1-5 (5)