ABSTRACT
Electrical stimulation of the neuromuscular system holds promise for both scientific and therapeutic biomedical applications. Supplying and maintaining the power necessary to drive stimulation chronically is a fundamental challenge in these applications, especially when high voltages or currents are required. Wireless systems, in which energy is supplied through near field power transfer, could eliminate complications caused by battery packs or external connections, but currently do not provide the harvested power and voltages required for applications such as muscle stimulation. Here, we introduce a passive resonator optimized power transfer design that overcomes these limitations, enabling voltage compliances of ± 20 V and power over 300 mW at device volumes of 0.2 cm2, thereby improving power transfer 500% over previous systems. We show that this improved performance enables multichannel, biphasic, current-controlled operation at clinically relevant voltage and current ranges with digital control and telemetry in freely behaving animals. Preliminary chronic results indicate that implanted devices remain operational over 6 weeks in both intact and spinal cord injured rats and are capable of producing fine control of spinal and muscle stimulation.
Subject(s)
Electric Power Supplies , Prostheses and Implants , Rats , Animals , Spinal Cord , Electric Stimulation/methods , Telemetry/methods , Wireless Technology , Electrodes, ImplantedABSTRACT
RNA interference (RNAi) has previously been shown to be effective in western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) larvae via oral delivery of synthetic double-stranded RNA (dsRNA) in an artificial diet bioassay, as well as by ingestion of transgenic corn plant tissues engineered to express dsRNA. Although the RNAi machinery components appear to be conserved in Coleopteran insects, the key steps in this process have not been reported for WCR. Here we characterized the sequence of events that result in mortality after ingestion of a dsRNA designed against WCR larvae. We selected the Snf7 ortholog (DvSnf7) as the target mRNA, which encodes an essential protein involved in intracellular trafficking. Our results showed that dsRNAs greater than or equal to approximately 60 base-pairs (bp) are required for biological activity in artificial diet bioassays. Additionally, 240 bp dsRNAs containing a single 21 bp match to the target sequence were also efficacious, whereas 21 bp short interfering (si) RNAs matching the target sequence were not. This result was further investigated in WCR midgut tissues: uptake of 240 bp dsRNA was evident in WCR midgut cells while a 21 bp siRNA was not, supporting the size-activity relationship established in diet bioassays. DvSnf7 suppression was observed in a time-dependent manner with suppression at the mRNA level preceding suppression at the protein level when a 240 bp dsRNA was fed to WCR larvae. DvSnf7 suppression was shown to spread to tissues beyond the midgut within 24 h after dsRNA ingestion. These events (dsRNA uptake, target mRNA and protein suppression, systemic spreading, growth inhibition and eventual mortality) comprise the overall mechanism of action by which DvSnf7 dsRNA affects WCR via oral delivery and provides insights as to how targeted dsRNAs in general are active against insects.
Subject(s)
Coleoptera/drug effects , Insect Control/methods , RNA Interference , RNA, Double-Stranded/toxicity , Analysis of Variance , Animals , Base Sequence , Biological Assay , Blotting, Western , Coleoptera/genetics , Endosomal Sorting Complexes Required for Transport/genetics , Endosomal Sorting Complexes Required for Transport/metabolism , Enzyme-Linked Immunosorbent Assay , Gastrointestinal Tract/metabolism , Larva/drug effects , Lethal Dose 50 , Molecular Sequence Data , RNA, Double-Stranded/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
BACKGROUND: Adult stem cells are known to have a reduced restorative capacity as we age and are more vulnerable to oxidative stress resulting in a reduced ability of the body to heal itself. We have previously reported that a proprietary nutraceutical formulation, NT-020, promotes proliferation of human hematopoietic stem cells in vitro and protects stem cells from oxidative stress when given chronically to mice in vivo. Because previous reports suggest that the blue green algae, Aphanizomenon flos-aquae (AFA) can modulate immune function in animals, we sought to investigate the effects of AFA on human stem cells in cultures. MATERIAL/METHODS: Two AFA products were used for extraction: AFA whole (AFA-W) and AFA cellular concentrate (AFA-C). Water and ethanol extractions were performed to isolate active compounds for cell culture experiments. For cell proliferation analysis, human bone marrow cells or human CD34+ cells were cultured in 96 well plates and treated for 72 hours with various extracts. An MTT assay was used to estimate cell proliferation. RESULTS: We report here that the addition of an ethanol extract of AFA-cellular concentrate further enhances the stem cell proliferative action of NT-020 when incubated with human adult bone marrow cells or human CD34+ hematopoietic progenitors in culture. Algae extracts alone had only moderate activity in these stem cell proliferation assays. CONCLUSIONS: This preliminary study suggests that NT-020 plus the ethanol extract of AFA cellular concentrate may act to promote proliferation of human stem cell populations.