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Full-Text Articles in Medical Specialties
Cell Encapsulation As A Potential Nondietary Therapy For Maternal Phenylketonuria, Donna Santillan, Mark Santillan, Stephen Hunter
Cell Encapsulation As A Potential Nondietary Therapy For Maternal Phenylketonuria, Donna Santillan, Mark Santillan, Stephen Hunter
Stephen K. Hunter
OBJECTIVE: The objective of this work was to determine whether cells overexpressing phenylalanine (Phe) hydroxylase (PAH) can significantly reduce Phe in vitro for potential use as a therapy for preventing maternal phenylketonuria. STUDY DESIGN: Human 293T and WRL68 cell lines were transiently and stably transfected to overexpress PAH. Cells were encapsulated within microspheres of sodium alginate. Timed measurements of Phe in media were performed using tandem mass spectrometry. RESULTS: Both nonencapsulated and encapsulated transiently transfected cells overexpressing PAH significantly reduced the Phe concentration in media by approximately 50% in comparison to mock-transfected cells. Cell line clones stably expressing PAH significantly …
Biodegradable Microspheres Containing Group B Streptococcus Vaccine: Immune Response In Mice, Stephen Hunter, M. Andracki, A. Krieg
Biodegradable Microspheres Containing Group B Streptococcus Vaccine: Immune Response In Mice, Stephen Hunter, M. Andracki, A. Krieg
Stephen K. Hunter
OBJECTIVE: This study seeks to show the feasibility of producing a group B Streptococcus (GBS) vaccine, which is capable of producing both a local IgA immune response at the mucosal surface where GBS is colonized and a humoral IgG response, which is capable of transplacental passive immunization. STUDY DESIGN: Inactivated GBS antigen was microencapsulated in poly (D, L-lactic-co-glycolic acid) (PLG) with a water-in-oil-in-water double emulsion technique. Immunostimulatory synthetic oligodeoxynucleotides containing cytidine-phosphate-guanosine (CpG) motifs were coencapsulated as a potent adjuvant. The ICR strain of mouse was used in these studies. Female mice with normal immune systems were immunized with the PLG …
In Vivo Biocompatibility Evaluation Of Cibacron Blue-Agarose, J. Kao, R. Rose, M. Yousef, Stephen Hunter, V. Rodgers
In Vivo Biocompatibility Evaluation Of Cibacron Blue-Agarose, J. Kao, R. Rose, M. Yousef, Stephen Hunter, V. Rodgers
Stephen K. Hunter
This study investigated the biocompatibility of Cibacron blue-agarose as a biomaterial for microencapsulation. Cibacron blue-agarose is known to have an affinity for albumin under certain pH conditions and in the proper steric environment. Thus it was postulated that the material's high affinity for host albumin might reduce a secondary immune response and reduce the fibrotic overgrowth that often accompanies transplanted foreign materials. In vivo tests were performed using the Lewis rat model. Both Cibacron blue-agarose and plain agarose disks were prepared, with some disks from each group being pre-exposed to sera from Lewis rats. The disks were transplanted into the …
Promotion Of Neovascularization Around Hollow Fiber Bioartificial Organs Using Biologically Active Substances, Stephen Hunter, J. Kao, Y. Wang, J. Benda, V. Rodgers
Promotion Of Neovascularization Around Hollow Fiber Bioartificial Organs Using Biologically Active Substances, Stephen Hunter, J. Kao, Y. Wang, J. Benda, V. Rodgers
Stephen K. Hunter
A limiting factor of the long-term function of bioartificial organs is oxygen delivery to the encapsulated tissue. This study determined whether incorporation of endothelial cell growth factor (ECGF) into the alginate core of a hollow fiber bioartificial organ will induce neovascularization around the hollow fiber. Polyethersulfone (PES) and polyvinylidine difluoride (PVDF) hollow fibers were examined. Endothelial cell growth factor was incorporated into sodium alginate, extruded into the lumen of hollow fibers, and cured in calcium chloride. Samples without ECGF were fabricated and used as controls. Hollow fibers were implanted into 16 rats. For each rat, two implants were placed subcutaneously …
Encapsulated Beta-Islet Cells As A Bioartificial Pancreas To Treat Insulin-Dependent Diabetes During Pregnancy, Stephen Hunter, Y. Wang, C. Weiner, Jennifer Niebyl
Encapsulated Beta-Islet Cells As A Bioartificial Pancreas To Treat Insulin-Dependent Diabetes During Pregnancy, Stephen Hunter, Y. Wang, C. Weiner, Jennifer Niebyl
Stephen K. Hunter
OBJECTIVE: Our purpose was to determine the effectiveness of the bioartificial pancreas technique in correcting (1) maternal carbohydrate metabolism and (2) fetal malformation rates in a pregnant diabetic animal model. STUDY DESIGN: Insulin secretion from encapsulated rat islets cultured in the presence of homologous rat prolactin was determined and compared with that of controls. Streptozotocin-induced diabetic Balb/c mice were then transplanted with rat islet cells encapsulated within alginate microbeads and were then bred. Blood glucose determinations were made after transplantation and throughout gestation. Pups were delivered by cesarean section on day 19 of gestation. Outcome parameters from the transplanted study …
Protective Immunization In Mice Against Group B Streptococci Using Encapsulated C5a Peptidase, Donna Santillan, M. Andracki, Stephen Hunter
Protective Immunization In Mice Against Group B Streptococci Using Encapsulated C5a Peptidase, Donna Santillan, M. Andracki, Stephen Hunter
Stephen K. Hunter
OBJECTIVE: The purpose of the study was to test whether C5a peptidase encapsulated within a biodegradable polymer can act as a vaccine and elicit an immune response to prevent group B streptococci (GBS) infection in mice and provide protection to pups. STUDY DESIGN: C5a peptidase was encapsulated in semipermeable microspheres of poly(lactide-co-glycolide). Female ICR mice were immunized with encapsulated C5a peptidase, free C5a peptidase, or empty microparticles. Booster doses were given at days 21 and 42. Antibody responses were measured by enzyme-linked immunosorbent assay. Challenge with GBS type III was performed 4 days after the final booster in the vaginal …
Theoretical Prediction Of Induction Period From Transient Pore Evolvement In Polyester-Based Microparticles, A. Zhao, Stephen Hunter, V. Rodgers
Theoretical Prediction Of Induction Period From Transient Pore Evolvement In Polyester-Based Microparticles, A. Zhao, Stephen Hunter, V. Rodgers
Stephen K. Hunter
A model was developed and compared to experimental results for prediction of the induction period during drug delivery from various compositions of biodegradable copolymer PLGA microparticles. The uniqueness of this model is that it considers transient pore evolvement and uses the kinetic parameters of polymer degradation, which are independent of experimental measurements of microparticle erosion, in its analysis. Delivery data from PLGA microparticles (50:50, 75:25, and 85:15) releasing ovalbumin (OVA, 46 kDa) and bovine serum albumin (BSA, 66 kDa) were determined and used as the model systems. Experimental measurements were carried out from 85 to 150 days depending on the …
Bioartificial Pancreas Use In Diabetic Pregnancy, Stephen Hunter, Y. Wang, V. Rodgers
Bioartificial Pancreas Use In Diabetic Pregnancy, Stephen Hunter, Y. Wang, V. Rodgers
Stephen K. Hunter
The purpose of this study was to evaluate the feasibility and effectiveness of Bioartificial Pancreas (BAP) technology use during diabetic pregnancy. In particular, the study asked 1) can microencapsulated islet cells effectively correct carbohydrate metabolism during diabetic pregnancy and 2) will such therapy, if initiated before conception, eliminate diabetes-induced congenital malformations in the fetus? Streptozotocin-induced diabetic female mice (ICR) received transplants of rat islets encapsulated within alginate microbeads. Animals were placed with male mice and bred. Random, nonfasting blood glucose (BG) determinations were made posttransplantation and throughout pregnancy. Pups were delivered by cesarean section on day 19 of gestation. Outcome …
Present And Future Perspectives On The Use Of Free Or Encapsulated Pancreatic Islet Cell Transplantation As A Treatment Of Pregnancy Complicated By Type 1 Diabetes, Stephen Hunter
Stephen K. Hunter
Pregnancies complicated by insulin-dependent diabetes mellitus (IDDM) pose significant health risks to both the mother and her developing fetus. Congenital malformations in the offspring of diabetic mothers have an incidence which is 2-5 times that seen in the background. Euglycemia in the first trimester of pregnancy can reduce this incidence, but achieving euglycemia with conventional exogenous insulin therapy is both costly and difficult. Even with intense insulin dosage adjustments, the blood glucose profile of the diabetic pregnant patient does not mimic that seen in nondiabetic patients. Both the difficulties and inadequacies of conventional therapy for IDDM-complicated pregnancy provide a stimulus …
Mathematical Modeling Of Myoglobin Facilitated Transport Of Oxygen In Devices Containing Myoglobin-Expressing Cells, H. Tilakaratne, Stephen Hunter, V. Rodgers
Mathematical Modeling Of Myoglobin Facilitated Transport Of Oxygen In Devices Containing Myoglobin-Expressing Cells, H. Tilakaratne, Stephen Hunter, V. Rodgers
Stephen K. Hunter
Low pO(2) is perhaps the most significant factor in artificial pancreas failure. In these environments, not only is the beta cell production of insulin reduced, but the cell death rate is also significantly higher. Mathematical models are developed to test the feasibility of facilitated oxygen transport in enhancing O(2) flux to genetically engineered cells in a bioartificial device such as a pancreas. For this device, it is proposed that beta cells be genetically engineered to express myoglobin throughout the cell. In addition, the significance of including myoglobin throughout the alginate matrix present to provide immuno-protection for the transplanted cells is …