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Biomedical subjects

Duane F Bruley

Publications and source records attributed to Duane F Bruley.

14 recordsLinked to original sources
PubMed2005

Process scale-up studies for protein C separation using IMAC.

Protein C (PC) is the pivotal anticoagulant and antithrombotic in the human coagulation cascade. PC deficiency can disturb the blood hemostasis and cause thrombosis, inhibiting oxygen transport to tissue, and resulting in major medical problems such as deep vein thrombosis (DVT). The current treatment can cause bleeding and other major medical problems. PC circulates in the blood as a zymogen and is only activated when and where it is needed. PC is a safe anticoagulant without harmful side effects. A combination of ion-exchange chromatography and IMAC IDA-Cu was studied for the relatively large scaled PC separation from Cohn fraction IV-1. Almost half of the active PC was recovered by using this process. In future work, we will verify the linearity of the IMAC column scale-up. This process can be used to produce PC from Cohn fraction IV-1 at large quantities and low cost to treat PC-deficient patients.

Anticoagulants↗
PubMed2005

Protein C production: metal ion/protein interfacial interaction in immobilized metal affinity chromatography.

Protein C (PC) is an essential blood factor in the human blood coagulation cascade. PC can help achieve blood hemostasis in many deadly disease conditions such as sepsis, cancer, HIV, etc.; reduced oxygen transport due to blood agglutination within the body can cause tissue death and organ failure as a result of low oxygen transport. Our goal is to produce large quantities of low cost zymogen PC for the treatment and prevention of blood clotting resulting from many disease states, as well as provide an effective therapy for PC deficiency. Current studies show that Immobilized Metal Affinity Chromatography (IMAC) has high specificity and can be used for difficult separations among homologous proteins at relatively low cost compared to current methods, such as Immunoaffinity Chromatography. Thus, we are investigating the optimization of IMAC for the separation and purification of PC from Cohn fraction IV-I. Molecular interactions within the chromatography column involve many parameters that include: the use and type of chromatographic gel and buffer solution, the pH, temperature, metal ion, chelator, and the sequence and structure of the protein itself. These parameters all influence the protein's interaction with the column. Experimental equilibrium isotherms show that PC has primary and secondary binding characteristics, demonstrating that the interaction is not just a simple process of one protein binding to one metal ion. Understanding the thermodynamics of interfacial interaction between proteins and surface-bound Cu2+ is essential to optimizing IMAC for PC purification, as well as for separation of other proteins in general. Hence we are undertaking theoretical and experimental studies of IDA-Cu/PC adsorption. The differences in structures of PC and other critical homologous blood factors are examined using the protein visualization program Cn3D. A better understanding of the interfacial phenomena will help determine the most effective conditions to achieve our goal.

Adsorption↗
PubMed2005

Modeling behavior of protein C during and after subcutaneous administration.

Protein C is an important blood factor protein that regulates the blood coagulation process. Deficiency of protein C can lead to excessive coagulation that results in lack of tissue oxygenation, causing conditions such as deep vein thrombosis, pulmonary embolism, and stroke. Human protein C has been approved as a treatment for congenital protein C deficiency; however, the therapy requires frequent injections, due to the short residence time of the protein. Subcutaneous administration has been examined as an alternative to increase residence time and decrease injection frequency, thereby creating a more patient-friendly dosing regimen. In order to design an efficient injection or infusion protocol for subcutaneously administered proteins, it is important to accurately model the behavior (absorption, distribution, elimination) of these proteins in the body. However, several factors involved in a subcutaneous injection of the protein make modeling this behavior a challenging task. For example, absorption of the drug from the subcutaneous site into the blood stream can be variable depending on the site of injection, physical activity of the patient, etc. Furthermore, degradation of the protein can occur at the site of injection and further modify its absorption. The objective of this work was to demonstrate the utility of frequency response modeling as an alternative method to analyze the behavior of subcutaneously administered protein C. The results of our study indicate that if the dose range yielding the constant clearance of protein C is identified for the patient, models of that type, as presented in our study, can be used to adjust optimal dosing of protein C necessary to reach prescribed levels of the protein in this patient at desired time points, both specified by treatment requirements.

Half-Life↗
PubMed2003

Protein C separation from human blood plasma derivatives using low cost chromatography.

Protein C (PC) deficiency can cause thrombosis, inhibiting oxygen transport to tissue thus resulting in many complications, including death. Present treatment can cause catastrophic bleeding and other major medical problems. PC treatment has no bleeding or skin necrosis problems because it circulates in the blood as a zymogen and is only activated when and where it is needed. The vitamin K dependent (VKD) proteins are homologous proteins, making the separation of PC from plasma extremely difficult. Immobilized metal affinity chromatography (IMAC) is investigated to separate the VKD proteins to replace immunoaffinity chromatography, because of the high cost of monoclonal antibodies. An IDA-Cu column was found effective for the separation of PC from prothrombin, the most harmful contaminant. For Cohn fraction IV-1 separation, a DEAE column was found an efficient initial step, with about 25-fold PC purity increase. Following this step, an IDA-Cu column could remove many contaminants including prothrombin. The combination of DEAE and IDA-Cu resulted in PC purity increase of about 100-fold.

Chromatography, Affinity↗
PubMed2003

Polyphosphates and other phosphorus-containing polymers for drug delivery applications.

Poly(phosphate ester)s, polyphosphonates, and polyphosphazenes are three classes of phosphorus-containing polymers that have received wide attention over the past decade for their utility in biomedicine and tissue engineering. These three families of polymers can lead to a number of subclasses of polymers with varied properties. Significant research in this area has led to niche polymers with morphologies ranging from viscous gels to amorphous microparticles for utility in drug delivery. Furthermore, the pentavalency of phosphorus offers the potential for covalent linking of the drug. The classes of polymers discussed in this review are being explored in human clinical trials for vaccine delivery as well as delivery of oncolytic and CNS therapeutics. More applications in the areas of DNA delivery and tissue engineering are also being explored.

Delayed-Action Preparations↗
PubMed2002

Chelator, metal ion and buffer studies for protein C separation.

Protein C (PC) is the pivotal anticoagulant and antithrombotic in the human coagulation cascade. PC deficiency can result in major medical problems such as deep vein thrombosis (DVT), leading to tissue oxygen deprivation. PC treatment has no bleeding or skin necrosis problems because it circulates in the blood as a zymogen and is only activated when and where it is needed. One source of PC is transgenic animal milk. The major components in the milk, such as alpha-casein, beta-casein, kappa-casein, alpha-lactalbumin and beta-lactoglobulin, are proteins that must be separated from PC. Immobilized metal affinity chromatography (IMAC) is an inexpensive separation technology with relatively high specificity, and it has great potential for difficult protein separations. After systematic studies of different chelator, metal ion and buffers, the combination of iminodiacetic acid (IDA) and Fe was found to be effective to separate PC from major milk components. alpha-Lactalbumin and beta-lactoglobulin fell through the column in the starting buffer. PC was eluted. alpha-Casein, beta-casein, kappa-casein remained bound in the column after PC elution. This technology might be applied for PC separation from transgenic animal milk. It is very important for PC production in large quantities and at low cost to treat PC-deficient patients.

Animals↗