Darren Jay Hillegonds

In vivo degradation of 14C-labeled small intestinal submucosa (SIS) when used for urinary bladder repair.

The rate of in vivo degradation was determined for a naturally occurring biomaterial derived from the extracellular matrix of the small intestinal submucosa (SIS). The SIS was labeled by giving weekly intravenous injections of 10 microCi of 14C-proline to piglets from 3 weeks of age until the time of sacrifice at 26 weeks. The resultant SIS prepared from these pigs contained approximately 10(3) fold more 14C than unlabeled tissues. The labeled SIS was used to repair experimental defects in the urinary bladder of 10 dogs. The animals were sacrificed at post-operative times ranging from 3 days to 1 year and the remodeled urinary bladder tissue was harvested for evaluation of 14C by a combination of liquid scintillation counting and accelerator mass spectrometry. The remodeled tissue contained less than 10% of the 14C (disintegrations per minute/gram tissue wet weight) at 3 months post-surgery compared to the SIS biomaterial that was originally implanted. The SIS scaffold was replaced by host tissue that resembled normal bladder both in structure and function. After implantation, 14C was detected in highest concentrations in the blood and the urine. The SIS bioscaffold provides a temporary scaffold for tissue remodeling with rapid host tissue remodeling, degradation, and elimination via the urine when used as a urinary bladder repair device.

Re-generation of tissue about an animal-based scaffold: AMS studies of the fate of the scaffold

Abstract Small intestinal submucosa (SIS) is an unusual tissue, which shows great promise for the repair of damaged tissues in humans. When the SIS is used as a surgical implant, the porcine-derived material is not rejected by the host immune system, and in fact stimulates the constructive re-modeling of damaged tissue. In dogs, these SIS scaffolds have been used to grow new arteries, tendons, and urinary bladders. Moreover, the SIS scaffold tissue seems to disappear from the implant region after a few months. The fate of this SIS tissue is of considerable importance if it is to be used in human tissue repair. SIS is obtained from pigs. We have labeled the SIS in several pigs by intraveneous administration of 14 C enriched proline from the age of three weeks until they reach market weight. The prepared SIS was then implanted in dogs as scaffolds for urinary bladder patches. During the remaining life of each dog, blood, urine and feces samples were collected on a regular schedule. AMS analyses of these specimens were performed to measure the elimination rate of the SIS. At different intervals, the dogs were sacrificed. Tissue samples were analyzed by AMS to determine the whole-body distribution of the labeled SIS.

The PRIME Lab biomedical program

Abstract The biomedical accelerator mass spectrometry (AMS) initiative at PRIME Lab including the status of equipment and sample preparation is described. Several biomedical projects are underway involving one or more of the nuclides: 14C, 26Al and 41Ca. Routine production of CaF2 and graphite is taking place. Finally, the future direction and plans for improvement of the biomedical program at PRIME Lab are discussed.

Testing the atomic structure of beryllium with AMS

Abstract If the Pauli exclusion principle were violated, the electronic structure of Be could be 1s 4 (denoted by Be ′ ) rather than 1s 2 2s 2 . This paper describes the results of an experimental search for Be ′ , carried out at PRIME Lab, the Purdue Rare Isotope Measurement Laboratory. In the process of setting stringent constraints on Be ′ using samples of metallic Be, Be ore, natural gas, and air, we made several modifications to the PRIME Lab facility. These included a new Be-free source and the construction of a gas introduction system which coupled to the existing ion source. The modifications permitted us to reach limits which are a factor of nearly 300 better than those obtained in previous experiments.

Prime lab sample handling and data analysis for accelerator-based biomedical radiocarbon analysis

Processing and measurement of 200 biomedical samples has provided an opportunity to better understand the characteristics of accelerator mass spectrometry (AMS) analysis of such samples. We have utilized established procedures (Vogel 1992) and developed new methods for handling various biological samples. We have included secondary standards of known isotope ratio for all assays. A method of determining maximum precision for each unknown sample value is also reported. The presented data are an update of the ongoing radiocarbon AMS biomedical program at Purdue University.

Testing the Pauli Exclusion Principle with accelerator mass spectrometry

We report the results of a new experimental search for the Pauli-forbidden 1s4 state of Be, denoted by Be′. Using the Accelerator Mass Spectrometer facility at Purdue, we set limits on the abundance of Be′ in metallic Be, Be ore, natural gas, and air (10−14). Our results improve on those obtained in a previous search for Be′ by a factor of approximately 300.