Publications by authors named "Lisa Stehno-Bittel"

48 Publications

Hyaluronic Acid Hydrogel Microspheres for Slow Release Stem Cell Delivery.

ACS Biomater Sci Eng 2021 08 29;7(8):3754-3763. Epub 2021 Jul 29.

Likarda LLC, 10330 Hickman Mills Drive, Suite B, Kansas City, Missouri 64137, United States.

Cell therapies are hampered by a lack of available delivery systems, resulting in inconsistent outcomes in animal studies and human clinical trials. Hydrogel encapsulants offer a broad range of tunable characteristics in the design of cell delivery vehicles. The focus of the hydrogel field has been on durable encapsulants that provide long-term paracrine function of the cells. However, some cell therapies require cell-to-cell contact in order to elicit their effect. Controlled release microencapsulants would be beneficial in these situations, but appropriate polymers have not been adaptable to microsphere manufacturing because they harden too slowly. We developed and tested a novel microencapsulant formulation (acrylated hyaluronic acid: AHA) with degradation characteristics as a controlled release cell delivery vehicle. The properties of AHA microspheres were evaluated and compared to those of poly(ethylene glycol) diacrylate (PEGDA), a durable hydrogel. AHA microspheres possessed a higher swelling ratio, lower diffusion barrier, faster degradation rate, a lower storage modulus, and a larger average diameter than microspheres composed of PEGDA. Additionally, cell viability and release and short-term biocompatibility in immune competent Sprague-Dawley rats was assessed for each microsphere type. Compared to PEGDA, microspheres composed of AHA resulted in significantly less foreign body response as measured by a lack of cellularity or fibrotic ring in the surrounding tissue and no cellular infiltration into the microsphere. This study illustrates the potential of AHA microspheres as a degradable cell delivery system with superior encapsulated cell viability and biocompatibility with the surrounding tissue.
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http://dx.doi.org/10.1021/acsbiomaterials.1c00658DOI Listing
August 2021

Viability, yield and expansion capability of feline MSCs obtained from subcutaneous and reproductive organ adipose depots.

BMC Vet Res 2021 Jul 15;17(1):244. Epub 2021 Jul 15.

Likarda LLC, 10330 Hickman Mills Drive, Kansas City, MO, USA.

Background: The source of multipotent stromal cells (MSC) can have a significant influence on the health and expansion capacity of the cells. As the applications for allogeneic MSCs in the treatment of feline diseases increase, the location of the initial donor tissue must be analyzed. To date, comparisons have only been made between feline MSCs collected from bone marrow or abdominal fat. This is the first report to compare cells obtained from different adipose depots in the cat with a focus on clinically relevant donor tissues. The tissue was collected from 34 healthy cats undergoing spaying (fat around the ovaries and uterine horn) or subcutaneous fat collected during surgical procedures.

Results: The amount of starting material is essential to isolate sufficient MSCs. The total tissue yield from the subcutaneous fat was significantly greater than could be obtained from around the reproductive organs, leading to 3 times more MSCs per donor. However, the concentration of MSCs obtained from reproductive fat was higher than from subcutaneous fat. In addition, the viability of the MSCs from the reproductive fat was significantly higher than the subcutaneous fat. Since most spaying occurs in young cats (under 18 months) reproductive fat was collected from adult cats during spaying, illustrating that age did not alter the yield or viability of the MSCs. When sufficient tissue was collected, it was digested either mechanically or enzymatically. Mechanical digestion further decreased the viability and yield of MSCs from subcutaneous fat compared to enzymatic digestion. Biomarkers of stem cell characterization, expansion capacity and function were detected using qPCR. CD70, CD90 and CD105 were all expressed in high levels in the 3 groups. However, the reproductive fat had higher levels of CD73 with the mechanically digested subcutaneous fat having the least. Gata6 was detected in all samples while Sox2 and Sox17 were also detected with higher quantities found in the enzymatically digested subcutaneous fat. Negative control genes of Gata4 and Pdx1 showed no detection prior to 50 cycles. During the first three passages, age of the donor, location of the donor tissue, or digestion protocol had no effect on cell culture doubling times or cell viability.

Conclusions: While MSCs from reproductive fat had superior cells/tissue weight and initial viability, there were still dramatically fewer cells obtained compared to subcutaneous fat due to the limited amount of tissue surrounding the reproductive organs. Further, in P1-P3 cultures there were no differences noted in doubling time or cell viability between tissue obtained from reproductive or subcutaneous fat depots.
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http://dx.doi.org/10.1186/s12917-021-02948-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8281647PMC
July 2021

Improved harmonization of critical characterization assays across cell therapies.

Regen Med 2020 05 26;15(5):1661-1678. Epub 2020 Jun 26.

Likarda, LLC, 10330 Hickman Mills Drive, Kansas City, MO, USA.

The field of cell therapy has blossomed, providing exciting new options for treating a variety of diseases. While few cell therapy products have US FDA approval, there are thousands of cell treatments at various stages of development, pointing to a potential revolutionary shift in patient care. The expanding number and nature of cellular therapies necessitate greater standardization. Several international organizations are collaborating to pursue some level of global standardization, especially concerning cell banking. However, less harmonization surrounds assays used for critical quality characterization including: identity, purity, safety and potency. Frequently, there is divergence regarding the terms describing the characterization assays across regulatory authorities and guidances. This review summarizes the critical quality assays currently used for different categories of cell therapies. Areas of harmonization and an absence of standardization are highlighted. We propose potential solutions to facilitate harmonization of critical quality characterization assays and the language used to describe them.
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http://dx.doi.org/10.2217/rme-2020-0003DOI Listing
May 2020

A Versatile Microencapsulation Platform for Hyaluronic Acid and Polyethylene Glycol.

Tissue Eng Part A 2021 02 27;27(3-4):153-164. Epub 2020 Mar 27.

Likarda LLC, Kansas City, Missouri, USA.

Cell microencapsulation is a rapidly expanding field with broad potential for stem cell therapies and tissue engineering research. Traditional alginate microspheres suffer from poor biocompatibility, and microencapsulation of more advanced hydrogels is challenging due to their slower gelation rates. We have developed a novel, noncytotoxic, nonemulsion-based method to produce hydrogel microspheres compatible with a wide variety of materials, called core-shell spherification (CSS). Fabrication of microspheres by CSS derived from two slow-hardening hydrogels, hyaluronic acid (HA) and polyethylene glycol diacrylate (PEGDA), was characterized. HA microspheres were manufactured with two different crosslinking methods: thiolation and methacrylation. Microspheres of methacrylated HA (MeHA) had the greatest swelling ratio, the largest average diameter, and the lowest diffusion barrier. In contrast, PEGDA microspheres had the smallest diameters, the lowest swelling ratio, and the highest diffusion barrier, while microspheres of thiolated HA had characteristics that were in between the other two groups. To test the ability of the hydrogels to protect cells, while promoting function, diabetic NOD mice received intraperitoneal injections of PEGDA or MeHA microencapsulated canine islets. PEGDA microspheres reversed diabetes for the length of the study (up to 16 weeks). In contrast, islets encapsulated in MeHA microspheres at the same dose restored normoglycemia, but only transiently (3-4 weeks). Nonencapsulated canine islet transplanted at the same dose did not restore normoglycemia for any length of time. In conclusion, CSS provides a nontoxic microencapsulation procedure compatible with various hydrogel types.
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http://dx.doi.org/10.1089/ten.TEA.2019.0286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891217PMC
February 2021

The Flaws and Future of Islet Volume Measurements.

Cell Transplant 2018 07 28;27(7):1017-1026. Epub 2018 Jun 28.

2 Likarda, LLC, Kansas City, MO, USA.

When working with isolated islet preparations, measuring the volume of tissue is not a trivial matter. Islets come in a large range of sizes and are often contaminated with exocrine tissue. Many factors complicate the procedure, and yet knowledge of the islet volume is essential for predicting the success of an islet transplant or comparing experimental groups in the laboratory. In 1990, Ricordi presented the islet equivalency (IEQ), defined as one IEQ equaling a single spherical islet of 150 μm in diameter. The method for estimating IEQ was developed by visualizing islets in a microscope, estimating their diameter in 50 μm categories and calculating a total volume for the preparation. Shortly after its introduction, the IEQ was adopted as the standard method for islet volume measurements. It has helped to advance research in the field by providing a useful tool improving the reproducibility of islet research and eventually the success of clinical islet transplants. However, the accuracy of the IEQ method has been questioned for years and many alternatives have been proposed, but none have been able to replace the widespread use of the IEQ. This article reviews the history of the IEQ, and discusses the benefits and failings of the measurement. A thorough evaluation of alternatives for estimating islet volume is provided along with the steps needed to uniformly move to an improved method of islet volume estimation. The lessons learned from islet researchers may serve as a guide for other fields of regenerative medicine as cell clusters become a more attractive therapeutic option.
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http://dx.doi.org/10.1177/0963689718779898DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6158542PMC
July 2018

Deletion of the insulin receptor in sensory neurons increases pancreatic insulin levels.

Exp Neurol 2018 07 9;305:97-107. Epub 2018 Apr 9.

Department of Anatomy and Cell Biology, University of Kansas Medical Center, United States. Electronic address:

Insulin is known to have neurotrophic properties and loss of insulin support to sensory neurons may contribute to peripheral diabetic neuropathy (PDN). Here, genetically-modified mice were generated in which peripheral sensory neurons lacked the insulin receptor (SNIRKO mice) to determine whether disrupted sensory neuron insulin signaling plays a crucial role in the development of PDN and whether SNIRKO mice develop symptoms of PDN due to reduced insulin neurotrophic support. Our results revealed that SNIRKO mice were euglycemic and never displayed significant changes in a wide range of sensorimotor behaviors, nerve conduction velocity or intraepidermal nerve fiber density. However, SNIRKO mice displayed elevated serum insulin levels, glucose intolerance, and increased insulin content in the islets of Langerhans of the pancreas. These results contribute to the growing idea that sensory innervation of pancreatic islets is key to regulating islet function and that a negative feedback loop of sensory neuron insulin signaling keeps this regulation in balance. Our results suggest that a loss of insulin receptors in sensory neurons does not lead to peripheral nerve dysfunction. The SNIRKO mice will be a powerful tool to investigate sensory neuron insulin signaling and may give a unique insight into the role that sensory neurons play in modifying islet physiology.
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http://dx.doi.org/10.1016/j.expneurol.2018.04.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5963702PMC
July 2018

Improved yield of canine islet isolation from deceased donors.

BMC Vet Res 2017 Aug 22;13(1):264. Epub 2017 Aug 22.

University of Kansas Medical Center, MS 2002, Kansas City, KS, 66160, USA.

Background: Canine diabetes is a strikingly prevalent and growing disease, and yet the standard treatment of a twice-daily insulin injection is both cumbersome to pet owners and only moderately effective. Islet transplantation has been performed with repeated success in canine research models, but has unfortunately not been made available to companion animals. Standard protocols for islet isolation, developed primarily for human islet transplantation, include beating-heart organ donation, vascular perfusion of preservation solutions, specialized equipment. Unfortunately, these processes are prohibitively complex and expensive for veterinary use. The aim of the study was to develop a simplified approach for isolating canine islets that is compatible with the financial and logistical restrictions inherent to veterinary medicine for the purpose of translating islet transplantation to a clinical treatment for canine diabetes.

Results: Here, we describe simplified strategies for isolating quality islets from deceased canine donors without vascular preservation and with up to 90 min of cold ischemia time. An average of more than 1500 islet equivalents per kg of donor bodyweight was obtained with a purity of 70% (N = 6 animals). Islets were 95% viable and responsive to glucose stimulation for a week. We found that processing only the body and tail of the pancreas increased isolation efficiency without sacrificing islet total yield. Islet yield per gram of tissue increased from 773 to 1868 islet equivalents when the head of the pancreas was discarded (N = 3/group).

Conclusions: In summary, this study resulted in the development of an efficient and readily accessible method for obtaining viable and functional canine islets from deceased donors. These strategies provide an ethical means for obtaining donor islets.
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http://dx.doi.org/10.1186/s12917-017-1177-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5567429PMC
August 2017

Integration of mesenchymal stem cells into islet cell spheroids improves long-term viability, but not islet function.

Islets 2017 09 29;9(5):87-98. Epub 2017 Jun 29.

a Department of Physical Therapy and Rehabilitation Sciences , University of Kansas Medical Center , Kansas City , KS , USA.

Pancreatic islets, especially the large islets (> 150µm in diameter) have poor survival rates in culture. Co-culturing with mesenchymal stem cells (MSCs) has been shown to improve islet survival and function. However, most co-culture studies have been comprised of MSC surrounding islets in the media. The purpose of this study was to determine whether islet survival and function was improved when the 2 populations of cells were intermingled with each other in a defined geometry. Hybrid spheroids containing 25, 50 or 75 or 90% islets cells with appropriate numbers of MSCs were created along with spheroids comprised of only islet cells or only MSCs. Spheroids were tested for yield, viability, diameter, cellular composition, and glucose-stimulated insulin secretion. The 25% islet/75% MSC group created the fewest spheroids, with the poorest survival and insulin secretion and the largest diameter. The remaining groups were highly viable with average diameters under 80µm at formation. However, the hybrid spheroid groups preferred to cluster in islet-only spheroids. The 50, 75 and 90% islet cell groups had excellent long-term survival with 90-95% viability at 2 weeks in culture, compared with the islet only group that were below 80% viability. The glucose-stimulated insulin secretion was not statistically different for the 50, 75, or 90 groups when exposed to 2.4, 16.8, or 22.4 mM glucose. Only the spheroids with 25% islet cells had a statistically lower levels of insulin release, and the 100% had statistically higher levels at 22.4 mM glucose and in response to secretagogue. Thus, imbedded co-culture improved long-term viability, but failed to enhance glucose-stimulated insulin secretion in vitro.
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http://dx.doi.org/10.1080/19382014.2017.1341455DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5624285PMC
September 2017

Long-term cryopreservation of reaggregated pancreatic islets resulting in successful transplantation in rats.

Cryobiology 2017 06 5;76:41-50. Epub 2017 May 5.

University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, USA; Likarda, LLC, 2002 W 39th Avenue, Kansas City, KS 66103, USA. Electronic address:

Preservation of pancreatic islets for long-term storage of islets used for transplantation or research has long been a goal. Unfortunately, few studies on long-term islet cryopreservation (1 month and longer) have reported positive outcomes in terms of islet yield, survival and function. In general, single cells have been shown to tolerate the cryopreservation procedure better than tissues/multicellular structures like islets. Thus, we optimized a method to cryopreserve single islet cells and, after thawing, reaggregated them into islet spheroids. Cryopreserved (CP) single human islet cells formed spheroids efficiently within 3-5 days after thawing. Approximately 79% of islet cells were recovered following the single-cell cryopreservation protocol. Viability after long-term cryopreservation (4 weeks or more) was significantly higher in the CP islet cell spheroids (97.4 ± 0.4%) compared to CP native islets (14.6 ± 0.4%). Moreover, CP islet cell spheroids had excellent viability even after weeks in culture (88.5 ± 1.6%). Metabolic activity was 4-5 times higher in CP islet cell spheroids than CP native islets at 24 and 48 h after thawing. Diabetic rats transplanted with CP islet cell spheroids were normoglycemic for 10 months, identical to diabetic rats transplanted with fresh islets. However, the animals receiving fresh islets required a higher volume of transplanted tissue to achieve normoglycemia compared to those transplanted with CP islet cell spheroids. By cryopreserving single cells instead of intact islets, we achieved highly viable and functional islets after thawing that required lower tissue volumes to reverse diabetes in rats.
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http://dx.doi.org/10.1016/j.cryobiol.2017.04.010DOI Listing
June 2017

An Automated Multiplexed Hepatotoxicity and CYP Induction Assay Using HepaRG Cells in 2D and 3D.

SLAS Discov 2017 06 27;22(5):614-625. Epub 2017 Mar 27.

1 Likarda, LLC, Kansas City, KS, USA.

Drug-induced liver injury (DILI) and drug-drug interactions (DDIs) are concerns when developing safe and efficacious compounds. We have developed an automated multiplex assay to detect hepatotoxicity (i.e., ATP depletion) and metabolism (i.e., cytochrome P450 1A [CYP1A] and cytochrome P450 3A4 [CYP3A4] enzyme activity) in two-dimensional (2D) and three-dimensional (3D) cell cultures. HepaRG cells were cultured in our proprietary micromold plates and produced spheroids. HepaRG cells, in 2D or 3D, expressed liver-specific proteins throughout the culture period, although 3D cultures consistently exhibited higher albumin secretion and CYP1A/CYP3A4 enzyme activity than 2D cultures. Once the spheroid hepatic quality was assessed, 2D and 3D HepaRGs were challenged to a panel of DILI- and CYP-inducing compounds for 7 days. The 3D HepaRG model had a 70% sensitivity to liver toxins at 7 days, while the 2D model had a 60% sensitivity. In both the 2D and 3D HepaRG models, 83% of compounds were predicted to be CYP inducers after 7 days of compound exposure. Combined, our results demonstrate that an automated multiplexed liver spheroid system is a promising cell-based method to evaluate DILI and DDI for early-stage drug discovery.
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http://dx.doi.org/10.1177/2472555217701058DOI Listing
June 2017

Hyaluronic Acid/Collagen Hydrogel as an Alternative to Alginate for Long-Term Immunoprotected Islet Transplantation.

Tissue Eng Part A 2017 10 2;23(19-20):1088-1099. Epub 2017 Mar 2.

1 School of Engineering, University of Kansas , Lawrence, Kansas.

Alginate has long been the material of choice for immunoprotection of islets due to its low cost and ability to easily form microspheres. Unfortunately, this seaweed-derived material is notoriously prone to fibrotic overgrowth in vivo, resulting in premature graft failure. The purpose of this study was to test an alternative, hyaluronic acid (HA-COL), for in vitro function, viability, and allogeneic islet transplant outcomes in diabetic rats. In vitro studies indicated that the HA-COL gel had diffusion characteristics that would allow small molecules such as glucose and insulin to enter and exit the gel, whereas larger molecules (70 and 500 kDa dextrans) were impeded from diffusing past the gel edge in 24 h. Islets encapsulated in HA-COL hydrogel showed significantly improved in vitro viability over unencapsulated islets and retained their morphology and glucose sensitivity for 28 days. When unencapsulated allogeneic islet transplants were administered to the omentum of outbred rats, they initially were normoglycemic, but by 11 days returned to hyperglycemia. Immunohistological examination of the grafts and surrounding tissue indicated strong graft rejection. By comparison, when using the same outbred strain of rats, allogeneic transplantation of islets within the HA-COL gel reversed long-term diabetes and prevented graft rejection in all animals. Animals were sacrificed at 40, 52, 64, and 80 weeks for evaluation, and all were non-diabetic at sacrifice. Explanted grafts revealed viable islets in the transplant site as well as intact hydrogel, with little or no evidence of fibrotic overgrowth or cellular rejection. The results of these studies demonstrate great potential for HA-COL hydrogel as an alternative to sodium alginate for long-term immunoprotected islet transplantation.
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http://dx.doi.org/10.1089/ten.TEA.2016.0477DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6112162PMC
October 2017

A simple, reliable method for high-throughput screening for diabetes drugs using 3D β-cell spheroids.

J Pharmacol Toxicol Methods 2016 Nov - Dec;82:83-89. Epub 2016 Aug 20.

University of Kansas Medical Center, Department of Physical Therapy and Rehabilitation Science, 3901 Rainbow Blvd., Kansas City, KS 66160, United States; Likarda, LLC, 2002 W 39th Ave, Kansas City, KS 66103, United States. Electronic address:

Early screens for new diabetes drugs rely on monolayers of β-cells, which are known to be poor predictors of the in vivo response. Previously, we developed a method to create uniform islet spheroids from freshly-dispersed human donor tissue for drug screening. While the human engineered islets worked well to reduce donor-to-donor variability, it is difficult and expensive to obtain sufficient high-quality human islets for drug testing. Thus, this study utilized a genetically-modified β-cell culture line (INS-1832/13) in 2D and as 3D spheroids and compared the results to human islet tissue formed into spheroids using a high-throughput 384-well format. In response to increasing concentrations of glucose, all 3 groups increased insulin release, but the cultured β-cells (2D and 3D) were more sensitive to glucose (EC50 5.85mM for 2D β-cells, 16.24mM for 3D β-cell spheroids) than the human islet spheroids (EC50 53.69mM). The order of responses to glybenclamide was human spheroids >3D β-cell culture >2D β-cell culture. In response to caffeine, the β-cells in 2D or 3D were more responsive compared to the human islet spheroids (EC50 0.39 and 0.31mM for 2D and 3D β-cells respectively). When exposed to inhibitors of insulin secretion (nifedipine and diazoxide), the responses were more similar between groups. Z' calculations, indicative of assay quality, determined that the 3D β-cell spheroids reached the criteria of an excellent to ideal drug screen assay more consistently than the other test models. In conclusion, 3D β-cell spheroids from a cultured cell line can be used in HTS assays that, according to reference drugs tested here, are sensitive and predictive of the in vivo response.
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http://dx.doi.org/10.1016/j.vascn.2016.08.005DOI Listing
May 2017

Differences in insulin biosynthesis pathway between small and large islets do not correspond to insulin secretion.

Islets 2015 ;7(5):e1129097

b Department of Physical Therapy and Rehabilitation Science ; University of Kansas Medical Center ; Kansas City , KS USA.

In a variety of mammalian species, small islets secrete more insulin per volume than large islets. This difference may be due to diffusional limitations of large islets, or inherent differences in the insulin production pathways. The purpose of this study was to identify possible differences in the early phase of glucose-stimulated insulin biosynthesis between large and small islets. Isolated small and large rat islets were challenged with 30 minutes of high glucose. The expression of insulin gene transcription factors (MafA, NeuroD/ Beta2, and PDX-1), preproinsulin mRNA, proinsulin and insulin were compared between large and small islets. Under basal (low glucose) conditions, MafA and NeuroD had higher mRNA levels and greater protein amounts in large islets compared to small when normalized to GAPDH levels. 30 minutes of high glucose stimulation failed to alter the mRNA or subsequent protein levels of either gene. However, 30 minutes of high glucose suppressed activated PDX-1 protein levels in both small and large islets. High glucose stimulation did not statistically alter the preproinsulin mRNA (insulin 1 and insulin 2) levels. At the translational level, high glucose increased the proinsulin levels, and large islets showed a higher proinsulin content per cell than small islets. Insulin content per cell was not significantly different between small and large islets under basal or high glucose levels. The results fail to explain the higher level of insulin secretion noted in small versus large islets and may suggest that possible differences lie downstream in the secretory pathway rather than insulin biosynthesis.
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http://dx.doi.org/10.1080/19382014.2015.1129097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4878277PMC
November 2016

Arum Palaestinum with isovanillin, linolenic acid and β-sitosterol inhibits prostate cancer spheroids and reduces the growth rate of prostate tumors in mice.

BMC Complement Altern Med 2015 Aug 5;15:264. Epub 2015 Aug 5.

Genzada Pharmaceuticals, LLC, 205 S. Broadway, Sterling, KS, 67579, USA.

Background: Arum palaestinum is a plant commonly found in the Middle East that is ingested as an herbal remedy to fight cancer. However, no studies have examined the direct effect of the plant/plant extract on tumor growth in an animal model.

Methods: Verified prostate cancer cells were plated as 3D spheroids to determine the effect of extract from boiled Arum Palaestinum Boiss roots. In addition, male NU/NU mice (8 weeks old) with xenograft tumors derived from the prostate cancer cell line were treated daily with 1000 mg/kg body weight gavage of the suspension GZ17. The tumor growth was measured repeatedly with calipers and the excised tumors were weighed at the termination of the 3 week study. Control mice (10 mice in each group) received vehicle in the same manner and volume.

Results: The number of live prostate cancer cells declined in a dose/dependent manner with a 24 h exposure to the extract at doses of 0.015 to 6.25 mg/mL. A fortified version of the extract (referred to as GZ17) that contained higher levels of isovanillin, linolenic acid and β-sitosterol had a stronger effect on the cell death rate, shifting the percentage of dead cells from 30 % to 55 % at the highest dose while the vehicle control had no effect on cell numbers. When GZ17 was applied to non-cancer tissue, in this case, human islets, there was no cell death at doses that were toxic to treated cancer cells. Preliminary toxicity studies were conducted on rats using an up-down design, with no signs of toxic effect at the highest dose. NU/NU mice with xenograft prostate tumors treated with GZ17 had a dramatic inhibition of tumor progression, while tumors in the control group grew steadily through the 3 weeks. The rate of tumor volume increase was 73 mm(3)/day for the vehicle group and 24 mm(3)/day for the GZ17 treated mice. While there was a trend towards lower excised tumor weight at study termination in the GZ17 treatment group, there was no statistical difference.

Conclusions: Fortified Arum palaestinum Boiss caused a reduction in live cells within prostate cancer spheroids and blocked tumor growth in xenografted prostate tumors in mice without signs of toxicity.
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http://dx.doi.org/10.1186/s12906-015-0774-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4525741PMC
August 2015

A Simple Method to Replace Islet Equivalents for Volume Quantification of Human Islets.

Cell Transplant 2015 15;24(7):1183-94. Epub 2014 May 15.

Likarda, LLC, Kansas City, KS, USA.

Human islets come in a variety of sizes and shapes, and the total volume of islets used for research or clinical transplants must be estimated in a manner that is simple and valid. Islet equivalent (IEQ) measurements are the standard estimate of islet volume. We published a new method (the Kansas method) for estimating rat islet volume using cell numbers that was reliable and valid. Here we modified the method for human islets. We measured the dimensions of isolated human islets showing that they are not spherical and became less so in larger islets, with an average smallest/largest diameter ratio of 0.73 in large islets and 0.85 in small islets. Human islets were individually loaded into 96-well plates, dissociated into single cells, and the total cell number per islet determined with computer-assisted cytometry. Based on the counted cell number per islet, a regression model was created to convert islet diameter to cell number with a high R(2) value (0.99). Separate regression equations for male and female donors or young and old donors were not significantly different than the pooled data and did not improve the regression values. There was an inverse correlation between the cell number per IEQ and islet size. The Kansas method was validated with ATP/cell and cell viability data. Compared to the actual cell count, conventional IEQ measurements overestimated tissue volume of large islets by nearly double. Examples of differences in results obtained from the same data sets normalized to IEQ or the Kansas method included viability and insulin secretion concentrations. The implications of the error associated with the current IEQ method of volume estimation are discussed.
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http://dx.doi.org/10.3727/096368914X681928DOI Listing
April 2016

Long-term liraglutide treatment is associated with increased insulin content and secretion in β-cells, and a loss of α-cells in ZDF rats.

Pharmacol Res 2013 Oct 26;76:58-66. Epub 2013 Jul 26.

Division of Endocrinology, University of Kansas Medical Center, Kansas City, KS, USA.

The ultimate treatment goal of diabetes is to preserve and restore islet cell function. Treatment of certain diabetic animal models with incretins has been reported to preserve and possibly enhance islet function and promote islet cell growth. The studies reported here detail islet cell anatomy in animals chronically treated with the incretin analog, liraglutide. Our aim was to quantitatively and qualitatively analyze islet cells from diabetic animals treated with vehicle (control) or liraglutide to determine whether normal islet cell anatomy is maintained or enhanced with pharmaceutical treatment. We harvested pancreata from liraglutide and vehicle-treated Zucker Diabetic Fatty (ZDF) rats to examine islet structure and function and obtain isolated islets. Twelve-week-old male rats were assigned to 3 groups: (1) liraglutide-treated diabetic, (2) vehicle-treated diabetic, and (3) lean non-diabetic. Liraglutide was given SC twice daily for 9 weeks. As expected, liraglutide treatment reduced body weight by 15% compared to the vehicle-treated animals, eventually to levels that were not different from lean controls. At the termination of the study, blood glucose was significantly less in the liraglutide-treated rats compared to vehicle treated controls (485.8±22.5 and 547.2±33.1mg/dl, respectively). Insulin content/islet (measured by immunohistochemistry) was 34.2±0.7 pixel units in vehicle-treated rats, and 54.9±0.6 in the liraglutide-treated animals. Glucose-stimulated insulin secretion from isolated islets (measured as the stimulation index) was maintained in the liraglutide-treated rats, but not in the vehicle-treated. However, liraglutide did not preserve normal islet architecture. There was a decrease in the glucagon-positive area/islet and in the α-cell numbers/area with liraglutide treatment (6.5 cells/field), compared to vehicle (17.9 cells/field). There was an increase in β-cell numbers, the β- to α-cell ratio that was statistically higher in the liraglutide-treated rats (24.3±4.4) compared to vehicle (9.1±2.8). Disrupted mitochondria were more commonly observed in the α-cells (51.9±10.3% of cells) than in the β-cells (27.2±4.4%) in the liraglutide-treated group. While liraglutide enhanced or maintained growth and function of certain islet cells, the overall ratio of α- to β-cells was decreased and there was an absolute reduction in islet α-cell content. There was selective disruption of intracellular α-cell organelles, representing an uncoupling of the bihormonal islet signaling that is required for normal metabolic regulation. The relevance of the findings to long-term liraglutide treatment in people with diabetes is unknown and should be investigated in appropriately designed clinical studies.
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http://dx.doi.org/10.1016/j.phrs.2013.07.005DOI Listing
October 2013

Elimination of T cell reactivity to pancreatic β cells and partial preservation of β cell activity by peptide blockade of LFA-1:ICAM-1 interaction in the NOD mouse model.

Clin Immunol 2013 Aug 9;148(2):149-61. Epub 2013 May 9.

Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA.

In insulin dependent diabetes mellitus (T1D), self-reactive T cells infiltrate pancreatic islets and induce beta cell destruction and dysregulation of blood glucose. A goal is to control only the self-reactive T cells, leaving the remainder of the T cell population free to protect the host. One approach is blockade of the second signal for T cell activation while allowing the first (antigen-specific) signal to occur. This work proposes that small peptides that block interaction of second signals delivered through the counter receptors LFA-1:ICAM-1 will induce attacking T cells (receiving the antigen signal) to become anergic or undergo apoptosis. In NOD mice, the peptides eliminated T cell reactivity against pancreatic antigens and reduced cellular infiltration into islets, which retained stronger density of insulin staining at five weeks after cessation of therapy. In in vitro studies the peptides induced nonresponsiveness during activation of T cells from mice and from human peripheral blood.
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http://dx.doi.org/10.1016/j.clim.2013.04.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3770271PMC
August 2013

Variations in rodent models of type 1 diabetes: islet morphology.

J Diabetes Res 2013 13;2013:965832. Epub 2013 May 13.

Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS 66160, USA.

Type 1 diabetes (T1D) is characterized by hyperglycemia due to lost or damaged islet insulin-producing β -cells. Rodent models of T1D result in hyperglycemia, but with different forms of islet deterioration. This study focused on 1 toxin-induced and 2 autoimmune rodent models of T1D: BioBreeding Diabetes Resistant rats, nonobese diabetic mice, and Dark Agouti rats treated with streptozotocin. Immunochemistry was used to evaluate the insulin levels in the β -cells, cell composition, and insulitis. T1D caused complete or significant loss of β -cells in all animal models, while increasing numbers of α -cells. Lymphocytic infiltration was noted in and around islets early in the progression of autoimmune diabetes. The loss of lymphocytic infiltration coincided with the absence of β -cells. In all models, the remaining α - and δ -cells regrouped by relocating to the islet center. The resulting islets were smaller in size and irregularly shaped. Insulin injections subsequent to induction of toxin-induced diabetes significantly preserved β -cells and islet morphology. Diabetes in animal models is anatomically heterogeneous and involves important changes in numbers and location of the remaining α - and δ -cells. Comparisons with human pancreatic sections from healthy and diabetic donors showed similar morphological changes to the diabetic BBDR rat model.
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http://dx.doi.org/10.1155/2013/965832DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3671304PMC
January 2014

Small human islets comprised of more β-cells with higher insulin content than large islets.

Islets 2013 Mar-Apr;5(2):87-94. Epub 2013 Mar 1.

School of Medicine, University of Kansas Medicine Center, Kansas City, KS, USA.

For the past 30 years, data have suggested that unique islet populations exist, based on morphology and glucose sensitivity. Yet little has been done to determine the mechanism of these functional differences. The purpose of this study was to determine whether human islets were comprised functionally unique populations, and to elucidate a possible mechanism. Islets or pancreatic sections from 29 human donors were analyzed. Islets were isolated and measured for insulin secretion, cell composition and organization, insulin and glucagon granule density and insulin content. Insulin secretion was significantly greater in small compared with large islets. In sectioned human pancreata, β-cells comprised a higher proportion of the total endocrine cells in small islets (63%) than large islets (39%). A higher percentage of β-cells in small islets contacted blood vessels (44%) compared with large islets (31%). Total insulin content of isolated human islets was significantly greater in the small (1323 ± 512 μIU/IE) compared with large islets (126 ± 48 μIU/IE). There was less immunostaining for insulin in the large islets from human pancreatic sections, especially in the core of the islet, compared with small islets. The results suggest that differences in insulin secretion between large and small islets may be due to a higher percentage of β-cells in small islets with more β-cells in contact with blood vessels and a higher concentration of insulin/β-cell in small islets.
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http://dx.doi.org/10.4161/isl.24780DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4204020PMC
January 2014

A novel three-dimensional stromal-based model for in vitro chemotherapy sensitivity testing of leukemia cells.

Leuk Lymphoma 2014 Feb 15;55(2):378-91. Epub 2013 May 15.

Hematology/Oncology, Blood and Marrow Transplant Program.

The disparate response of leukemia cells to chemotherapy in vivo, compared to in vitro, is partly related to the interaction of leukemic cells and the three-dimensional bone marrow stromal microenvironment. We investigated the effects of chemotherapy agents on leukemic cell lines co-cultured with human bone marrow mesenchymal stem cells (hu-BM-MSCs) in a three-dimensional model (3D). Comparison was made to leukemic cells treated in suspension, or grown on a hu-BM-MSC monolayer (2D conditions). We demonstrated that leukemic cells cultured in 3D were more resistant to drug-induced apoptosis compared to cells cultured in 2D or in suspension. We also demonstrated significant differences in leukemic cell response to chemotherapy using different leukemic cell lines cultured in 3D. We suggest that the differential responses to chemotherapy in 3D may be related to the expression of N-cadherin in the co-culture system. This unique model provides an opportunity to study leukemic cell responses to chemotherapy in 3D.
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http://dx.doi.org/10.3109/10428194.2013.793323DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4090917PMC
February 2014

Expression and regulation of nampt in human islets.

PLoS One 2013 11;8(3):e58767. Epub 2013 Mar 11.

Section of Endocrine/Diabetes, Children's Mercy Hospital and University of Missouri-Kansas City School of Medicine, Kansas City, Missouri, United States of America.

Nicotinamide phosphoribosyltransferase (Nampt) is a rate-limiting enzyme in the mammalian NAD+ biosynthesis of a salvage pathway and exists in 2 known forms, intracellular Nampt (iNampt) and a secreted form, extracellular Nampt (eNampt). eNampt can generate an intermediate product, nicotinamide mononucleotide (NMN), which has been reported to support insulin secretion in pancreatic islets. Nampt has been reported to be expressed in the pancreas but islet specific expression has not been adequately defined. The aim of this study was to characterize Nampt expression, secretion and regulation by glucose in human islets. Gene and protein expression of Nampt was assessed in human pancreatic tissue and isolated islets by qRT-PCR and immunofluorescence/confocal imaging respectively. Variable amounts of Nampt mRNA were detected in pancreatic tissue and isolated islets. Immunofluorescence staining for Nampt was found in the exocrine and endocrine tissue of fetal pancreas. However, in adulthood, Nampt expression was localized predominantly in beta cells. Isolated human islets secreted increasing amounts of eNampt in response to high glucose (20 mM) in a static glucose-stimulated insulin secretion assay (GSIS). In addition to an increase in eNampt secretion, exposure to 20 mM glucose also increased Nampt mRNA levels but not protein content. The secretion of eNampt was attenuated by the addition of membrane depolarization inhibitors, diazoxide and nifedipine. Islet-secreted eNampt showed enzymatic activity in a reaction with increasing production of NAD+/NADH over time. In summary, we show that Nampt is expressed in both exocrine and endocrine tissue early in life but in adulthood expression is localized to endocrine tissue. Enzymatically active eNampt is secreted by human islets, is regulated by glucose and requires membrane depolarization.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0058767PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3594147PMC
December 2013

Organ-based response to exercise in type 1 diabetes.

ISRN Endocrinol 2012 2;2012:318194. Epub 2012 Dec 2.

Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS 66160, USA.

While significant research has clearly identified sedentary behavior as a risk factor for type 2 diabetes and its subsequent complications, the concept that inactivity could be linked to the complications associated with type 1 diabetes (T1D) remains underappreciated. This paper summarizes the known effects of exercise on T1D at the tissue level and focuses on the pancreas, bone, the cardiovascular system, the kidneys, skeletal muscle, and nerves. When possible, the molecular mechanisms underlying the benefits of exercise for T1D are elucidated. The general benefits of increased activity on health and the barriers to increased exercise specific to people with T1D are discussed.
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http://dx.doi.org/10.5402/2012/318194DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3518066PMC
December 2012

KU-32, a novel drug for diabetic neuropathy, is safe for human islets and improves in vitro insulin secretion and viability.

Exp Diabetes Res 2012 1;2012:671673. Epub 2012 Nov 1.

Department of Pharmacology and Toxicology, University of Kansas, 5064 Malott Hall, Lawrence, KS 66045, USA.

KU-32 is a novel, novobiocin-based Hsp90 inhibitor that protects against neuronal glucotoxicity and reverses multiple clinical indices of diabetic peripheral neuropathy in a rodent model. However, any drug with potential for treating diabetic complications must also have no adverse effects on the function of pancreatic islets. Thus, the goal of the current study was to assess the effect of KU-32 on the in vitro viability and function of human islets. Treating human islets with KU-32 for 24 hours showed no toxicity as assessed using the alamarBlue assay. Confocal microscopy confirmed that with a minimum of 2-day exposure, KU-32 improved cellular viability by blocking apoptosis. Functionally, isolated human islets released more glucose-stimulated insulin when preincubated in KU-32. However, diabetic BKS-db/db mice, a model for type 2 diabetes, administered KU-32 for 10 weeks did not show any significant changes in blood glucose and insulin levels, despite having greater insulin staining/beta cell in the pancreas compared to untreated BKS db/db mice. In summary, KU-32 did not harm isolated human islets and may even be protective. However, the effect does not appear significant enough to alter the in vivo metabolic parameters of diabetic mice.
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http://dx.doi.org/10.1155/2012/671673DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3503326PMC
May 2013

Engineering islets for improved performance by optimized reaggregation in a micromold.

Tissue Eng Part A 2013 Mar 5;19(5-6):604-12. Epub 2012 Nov 5.

Bioengineering Program, University of Kansas, Lawrence, Kansas, USA.

Isolated islets can provide a source of tissue for research, transplantation, and drug discovery to develop therapies for diabetes. Empirical modeling of islet diffusion barriers demonstrated that only the outermost layers of cells were exposed to glucose and sufficient oxygen levels, resulting in core cell death. Islets under a diameter of 100 μm exhibited a lower diffusion barrier, superior survival rates, and improved functional properties. Utilizing these observations, we engineered optimal islets by dispersing them into single cells and reaggregating them over several days in a micromold. These custom-designed micromolds contained conical-shaped recesses that enhanced reaggregation of cells into a defined geometry. The engineered islets, or Kanslets, were all under 100 μm in diameter, and had the same general cellular composition as native islets. Kanslets continued to produce new insulin molecules and had microvilli on the islet surface, much like native islets. The engineered islets had a statistically higher viability (percent of live cells), and increased glucose diffusion compared to native islets. In addition, they remained responsive to varying glucose levels by secreting insulin. When transplanted into diabetic rats, engineered islets performed reduced random blood glucose to normal levels within 48 h. Optimally, engineering islets may be a suitable alternative to utilizing native, isolated islet tissue for a variety of applications. Reaggregating tissue in an optimized manner using our engineered micromold approach has immense impact for three-dimensional tissue production and its subsequent use in research, drug discovery, and the clinic.
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http://dx.doi.org/10.1089/ten.TEA.2012.0553DOI Listing
March 2013

Generating CK19-positive cells with hair-like structures from Wharton's jelly mesenchymal stromal cells.

Stem Cells Dev 2013 Jan 19;22(1):18-26. Epub 2012 Oct 19.

Blood and Marrow Transplant Program, University of Kansas Medical Center , Kansas City, Kansas, USA.

Wharton's jelly mesenchymal stromal cells (WJMSCs) are considered mesenchymal, multipotent, and capable of differentiating into cells of mesodermal origin. Ectodermal differentiation from mesenchymal cells has been recently reported. Herein, we show for the first time that we can generate cytokeratin 19-positive cells and hair-like structures from WJMSCs in vitro using 2 separate methodologies that utilize osteogenic media to induce WJMSCs to undergo osteogenic differentiation. In one method, WJMSCs were seeded on a matrix isolated from Wharton's jelly following decellularization. In the other method, WJMSCs were cultured to form spheroids. Our findings demonstrate that WJMSCs may have the capacity for ectodermal differentiation.
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http://dx.doi.org/10.1089/scd.2012.0184DOI Listing
January 2013

Time-dependent alterations in rat macrovessels with type 1 diabetes.

Exp Diabetes Res 2012 23;2012:278620. Epub 2012 Jan 23.

Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS 66160, USA.

Vascular complications are associated with the progressive severity of diabetes, resulting in significant morbidity and mortality. This study quantifies functional vascular parameters and macrovascular structure in a rat model of type 1 diabetes. While there was no difference in the systemic arterial elastance (Ea) with 50 days of diabetes, changes were noted in the aorta and femoral artery including increased tunica media extracellular matrix content, decreased width of both the media and individual smooth muscle cell layers, and increased incidence of damaged mitochondria. Extracellular matrix proteins and elastin levels were significantly greater in the aorta of diabetic animals. These differences correlated with diminished matrix metalloprotease activity in the aorta of the diabetic animals. In conclusion, diabetes significantly altered the structure and ultrastructure of the aorta and femoral artery before systemic changes in arterial elastance could be detected.
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http://dx.doi.org/10.1155/2012/278620DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3270547PMC
June 2012

A replacement for islet equivalents with improved reliability and validity.

Acta Diabetol 2013 Oct;50(5):687-96

Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, MS 2002, 3901 Rainbow Blvd., Kansas City, KS, 66160, USA.

Islet equivalent (IE), the standard estimate of isolated islet volume, is an essential measure to determine the amount of transplanted islet tissue in the clinic and is used in research laboratories to normalize results, yet it is based on the false assumption that all islets are spherical. Here, we developed and tested a new easy-to-use method to quantify islet volume with greater accuracy. Isolated rat islets were dissociated into single cells, and the total cell number per islet was determined by using computer-assisted cytometry. Based on the cell number per islet, we created a regression model to convert islet diameter to cell number with a high R2 value (0.8) and good validity and reliability with the same model applicable to young and old rats and males or females. Conventional IE measurements overestimated the tissue volume of islets. To compare results obtained using IE or our new method, we compared Glut2 protein levels determined by Western Blot and proinsulin content via ELISA between small (diameter≤100 μm) and large (diameter≥200 μm) islets. When normalized by IE, large islets showed significantly lower Glut2 level and proinsulin content. However, when normalized by cell number, large and small islets had no difference in Glut2 levels, but large islets contained more proinsulin. In conclusion, normalizing islet volume by IE overestimated the tissue volume, which may lead to erroneous results. Normalizing by cell number is a more accurate method to quantify tissue amounts used in islet transplantation and research.
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http://dx.doi.org/10.1007/s00592-012-0375-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3898333PMC
October 2013

Exercise increases insulin content and basal secretion in pancreatic islets in type 1 diabetic mice.

Exp Diabetes Res 2011 11;2011:481427. Epub 2011 Sep 11.

Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS 66160, USA.

Exercise appears to improve glycemic control for people with type 1 diabetes (T1D). However, the mechanism responsible for this improvement is unknown. We hypothesized that exercise has a direct effect on the insulin-producing islets. Eight-week-old mice were divided into four groups: sedentary diabetic, exercised diabetic, sedentary control, and exercised control. The exercised groups participated in voluntary wheel running for 6 weeks. When compared to the control groups, the islet density, islet diameter, and β-cell proportion per islet were significantly lower in both sedentary and exercised diabetic groups and these alterations were not improved with exercise. The total insulin content and insulin secretion were significantly lower in sedentary diabetics compared to controls. Exercise significantly improved insulin content and insulin secretion in islets in basal conditions. Thus, some improvements in exercise-induced glycemic control in T1D mice may be due to enhancement of insulin content and secretion in islets.
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http://dx.doi.org/10.1155/2011/481427DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170797PMC
January 2012
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