Gabrielle A. Stryker

Evidence for Four Distinct Major Protein Components in the Paraflagellar Rod of Trypanosoma cruzi

The major structural proteins present in the paraflagellar rod of Trypanosoma cruzi migrate on SDS-polyacrylamide gels as two distinct electrophoretic bands. The gene encoding a protein present in the faster migrating band, designated PAR 2, has been identified previously. Here we report the isolation and partial characterization of three genes, designated par 1, par 3, and par 4, that encode proteins present in the two paraflagellar rod protein bands. Peptide-specific polyclonal antibodies and monoclonal antibodies against the four proteins encoded by these genes shows that PAR 1 and PAR 3 are present only in the slower migrating paraflagellar rod band, and that PAR 2 and PAR 4 are present only in the faster migrating band. Analysis of the nucleotide sequence of these genes and the amino acid sequence of the conceptual proteins encoded by them indicates that par 2 shares high sequence similarity with par 3 and both are members of a common gene family, of which par 1 may be a distant member. Analysis of gene copy number and steady-state RNA levels suggest that the close stoichiometric ratio of the four PAR proteins is likely maintained by homeostatic regulation of RNA levels rather than gene dosage.

Using a system-on-a-chip implantable device to filter circulating infected cells in blood or lymph

This paper describes a system on a chip (SoC) that makes use of nanoscale cellular adhesion mechanisms in an integrated electronic microsystem to filter infected cells from blood or lymph. An example of a human immunodeficiency virus-specific SoC is explored in depth. Such systems work in vivo, and blood and lymph are filtered on a continuous basis. With the intelligence on the chip, captured cells can be identified and lyzed, expelled, or otherwise acted upon. These types of systems transfer the burden of research from traditional chemotherapy to bioengineering and system design.

A model for Chagas disease with controlled spraying

Chagas disease is a vector-borne parasitic disease that infects mammals, including humans, through much of Latin America. This work presents a mathematical model for the dynamics of domestic transmission in the form of four coupled nonlinear differential equations. The four equations model the number of domiciliary vectors, the number of infected domiciliary vectors, the number of infected humans, and the number of infected domestic animals. The main interest of this work lies in its study of the effects of insecticide spraying and of the recovery of vector populations with cessation of spraying. A novel aspect in the model is that yearly spraying, which is currently used to prevent transmission, is taken into account. The models predictions for a representative village are discussed. In particular, the model predicts that if pesticide use is discontinued, the vector population and the disease can return to their pre-spraying levels in approximately 5–8 years.

Previous exposure to a low infectious dose of Leishmania major exacerbates infection with Leishmania infantum in the susceptible BALB/c mouse

The geographic distribution of Leishmania major overlaps with several other species of Leishmania. This study seeks to examine what effect previous exposure to L. major has on the outcome of infection with Leishmania infantum, the agent of virulent visceral leishmaniasis. The L. major immune response is well characterized by a strong Th1 response leading to resolution and protection against subsequent re-infection. A contrasting Th2 immune response leads to disseminated disease, while the role Th17 cytokines may play in Leishmania infection is still being explored. The cytokine profile, antibody titer, and parasite burden were evaluated in the susceptible BALB/c mouse after L. infantum infection in either naïve mice or those previously infected with a low/self-healing dose of L. major. Only IL-4 expression in mice previously exposed to L. major was found to be significantly increased over controls, a cytokine with an ambiguous role in L. infantum infection. However, disease exacerbation, with a notably higher parasite burden, was observed in the L. major exposed mice compared to the L. infantum only. Cross-reactive antibodies were seen in both groups of infected mice regardless of their immune history. Studies have shown a role for opsonizing antibodies leading to increased disease in visceral leishmaniasis. We speculate that cross-reactive antibodies may be playing a role in augmenting visceral disease in mice with immunological memory to L. major.

Detection of Vesicular Stomatitis Virus using a Capacitive Immunosensor

This paper describes the detection of vesicular stomatitis virus using a novel capacitive immunosensor technology, whereby the respective antibodies for the antigens were used as a means for chemical detection on separate sensors. Devices were fabricated using standard etching and metal plating techniques, followed by immobilization of antibodies. Detection of antigen was performed by measuring voltage change due to changes in capacitance as antigen bound to the antibody surface. Capacitance changes were detected upon binding of specific antigen to the surface. This rugged, prototype device detected VSV down to the 2 pg/ml range

An examination of the effect of an AC pulsed electric field on cell mortality in SWLA-2 hybridomas

This work describes the initial experimental setup and results involving the percentage cell lysis in SWLA-2 murine hybridomas produced by AC electric field pulses of varying amplitudes and pulse widths. Cells were cultured and separate samples examined at 24 hours. The frequency, pulse width and peak-to-peak voltage were varied. AC electric fields producing at least 1 V across the cell membrane appear to be more effective in producing cell lysis than similar fields producing lower membrane voltages. Additionally, higher frequencies, in the 10 kHz range, appear to be more effective than lower frequencies at membrane voltages above 1 V in producing cell lysis.

Modeling HIV-1 dynamics and the effects of decreasing activated infected T-cell count by filtration

Over the past 10 years mathematical models have been developed using differential equations for the progression of HIV-1 to AIDS in an infected patient. Additional terms and formulations are presented over time, as the disease is better understood. Experimentation has been used to obtain many of the modeling parameters. These previous works focus primarily on modeling the progression of the disease, some with intervention such as HAART drugs. Attempts have been made to filter HIV-1 and HIV-1-infected T-cells from the blood. A model is developed that characterizes the rate of filtrations impact on disease progression. Such studies could be also used to investigate the impact of an implantable HIV-1 filter. Proliferation rates of actively and latently infected T-cells are significant and have been incorporated into the models developed in this paper.

Electroporation-Induced Cell Lysis in SWLA-2 Hybridomas

This paper describes experimental results involving the percentage cell lysis in SWLA-2 murine hybridomas produced by square wave electric field pulses of 100, 200, and 300 V across a 1 mm gap width in a standard cuvette. Pulse lengths were of 0.2 and 0.6 ms duration; 1, 2, or 3 pulses were applied with 100 ms time interval between pulses. Cells were cultured and separate samples examined at 48 hours to determine cell mortality. Nearly 90% cell mortality was produced by applying 3 pulses at of 0.6 ms duration at 300 V

Cell Lysis in SWLA-2 Hybridomas due to 1 kHz AC Electric Fields

This paper describes results involving the percentage cell lysis of SWLA-2 murine hybridomas produced by AC electric field pulses at 1 kHz with pulse widths ranging from 1 ms to 1 second. Cells that had been exposed to the electric fields were cultured and replicate samples were examined at 48 hours to determine the number of viable cells

An examination of the effect of decaying exponential pulse electric fields on cell mortality in murine spleenocytes, hybridomas, and human natural killer cells

This work describes the percentage cell lysis produced by exponentially decaying electric field pulses of varying amplitudes and time constants. Three different cell types were examined: murine spleenocytes, hybridomas, and human natural killer. Cells were cultured and separate samples examined at 24 hours and 48 hours. Two sets of experiments were performed for each cell type. At 0.3 kV, the spleenocytes exhibited a mortality of roughly 50% twenty-four hours after exposure to the pulse; while at forty-eight hours the spleenocyte cell count had reduced to roughly 25% viable cells. All other cell types showed mortality consistently in excess of 80% at field pulse strengths of about 0.3 V/m.