PubMed Health⌕ Search

Biomedical subjects

Christopher Batich

Publications and source records attributed to Christopher Batich.

6 recordsLinked to original sources
PubMed2006

Self-assembled copper-capillary alginate gel scaffolds with oligochitosan support embryonic stem cell growth.

Biomaterial scaffolds are fundamental components of strategies aimed at engineering a wide range of tissues. Scaffolds possessing uniform, oriented microtubular architectures could be ideal for multiple tissues, but are challenging to produce. Therefore, we developed hydrogel scaffolds possessing regular, tubular microstructures from self-assembled copper-capillary alginate gel (CCAG). To abrogate the rapid dissolution of CCAG in cell culture media, we treated it with oligochitosan and created a stable oligochitosan-CCAG (OCCAG) polyelectrolyte complex. Fourier transform infrared spectroscopy confirmed polyelectrolyte complexation between alginate and oligochitosan. OCCAG retained capillary morphology, shrank anisotropically in bulk, lost Cu(2+) ions, and maintained (71.9 +/- 5.65)% of its mass in cell culture media. Next, we seeded mouse embryonic stem (ES) cells within OCCAG scaffolds, and examined cell morphology and quantified cell growth and viability over four days. ES cells were guided to form cylindrical structures of staggered cells within scaffold capillaries. Analysis of the total cells recovered from the scaffolds revealed exponential cell growth (normalized to day 0) that was statistically similar to gelatinized-plate controls. OCCAG-cultured ES cell viability was also not significantly different from controls at day 4. CCAG-derived scaffolds can therefore serve as a unique platform for stem cell-based tissue engineering.

Alginates↗
PubMed2006

Structural modifications in chronic microwire electrodes for cortical neuroprosthetics: a case study.

Long-term viability of chronic invasive neural probes is a necessary condition for extracting robust control signals directly from neural tissue. Although immune/tissue response is a leading factor in the degradation of single neuron recording, we investigate a second component of signal degradation connected to the structural changes associated with microwire electrodes chronically exposed to extracelluar environments in vivo. Scanning electron microscopy is used to assess the surface modifications to the electrodes after an implantation duration of four weeks in rats. The electrode developed a smooth fracture surface, a reduction of the metal diameter, and pitting in the insulation of the electrode structure. Over the duration of implantation, recording properties of the electrode were marked by a reduction in the peak-to-peak amplitude in neuronal firing.

Action Potentials↗
PubMed2006

Preoperative endovascular brain mapping for intraoperative volumetric image guidance: preliminary concept and feasibility in animal models.

OBJECT: The authors describe a novel concept for brain mapping in which an endovascular approach is used, and they demonstrate its feasibility in animal models. The purpose of endovascular brain mapping is to delineate clearly the nonfunctional brain parenchyma when a craniotomy is performed for resection. The nonfunctional brain will be stained with sharp visual margins, differentiating it from the functional, nonstained brain. The authors list four essential criteria for developing an ideal endovascular mapping agent, and they describe seven potential approaches for accomplishing a successful endovascular brain map. METHODS: Four Sprague-Dawley rats and one New Zealand white rabbit were used to determine initial feasibility of the procedure. The animals were anesthetized, and the internal carotid artery was catheterized. Four potential brain mapping agents were infused into the right hemisphere of the five animals. Afterward, the brains were removed and each was analyzed both grossly and histologically. Fluorescein and FD&C Green No. 3 provided good visual clarity and margins, but required blood-brain barrier (BBB) manipulation. Tantalum particles enabled avoidance of BBB manipulation, but provided inadequate visual clarity, probably because of their size. A Sudan black "cocktail" provided excellent clarity and margins despite remaining in the brain capillaries. CONCLUSIONS: This is a novel application of the endovascular approach, and has broad potential for clinical neurosurgical brain mapping. The animal models in this study establish the feasibility of the procedure. However, further study is required to demonstrate safety, minimize toxicity, investigate stain durability, and improve the characteristics of potential mapping agents. The authors are planning to conduct future studies for identification of mapping agents that do not require BBB manipulation or vascular occlusion.

Angiography, Digital Subtraction↗
PubMed2005

Effects of EGF and bFGF on irradiated parotid glands.

Radiotherapy is common treatment for head-and-neck cancer, during which the salivary glands are often included within the radiation field. The most common side effect of this treatment is the development of oral dryness (xerostomia). This study considers the administration of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF or FGF2) at physiological concentrations before and after irradiation in order to repair radiation-induced damage in salivary gland cells. As a preliminary examination of the efficacy of this approach we have characterized the effects of EGF and bFGF on the apoptotic response of 15-Gy irradiated rat salivary glands in vitro. Also, we have developed a controlled-release delivery system to effectively administer the growth factor to the gland since local delivery is essential to avoid unwanted protection of cancer cells. In vitro administration of bFGF prior to and immediately after irradiation partially protected (44%) the rat parotid gland. EGF did not show any significant radioprotective effect on parotid glands after a single 15-Gy irradiation dose. Encapsulation, storage and release of bFGF from biodegradable 50/50 PLGA microspheres did not affect the functionality of the growth factor in vitro.

Animals↗
PubMed2002

Improved method of recombinant AAV2 delivery for systemic targeted gene therapy.

A major hurdle in most current gene therapy modalities is the ability to transduce target tissues at very high efficiencies that ultimately lead to therapeutic levels of transgene expression. We have developed a novel method of recombinant adeno-associated virus 2 (rAAV) delivery that results in increased vector transduction efficiencies using microspheres reversibly conjugated to rAAV vectors. We hypothesize that conjugation to microspheres should result in a higher effective concentration of vector as well as longer relative exposure time of vector to target cells as it moves through the tissue vasculature. In vitro experiments demonstrate that the same level of transduction seen with free vector can be achieved using 1% of vector when conjugated to microspheres. In addition, using magnetic microspheres, the region of infection can be targeted. In vivo, we demonstrate that microsphere-mediated delivery of rAAV vector results in higher transduction efficiencies than delivery with free vector alone when administered either intramuscularly or intravenously. Furthermore, we demonstrate targeting of transgene expression to specific tissues by retention of microsphere-bound vector in the capillary bed. These studies demonstrate a novel method to deliver rAAV vectors more effectively that could prove to be a successful alternative mode of virus-mediated human gene therapy.

Animals↗