Lifetime analysis for wireless sensor networks

The communications industry anticipates that Wireless Sensor Networks (WSNs) are the emerging technology to greatly affect society. A WSN is composed of numerous sensor nodes which have the ability to sense, compute and communicate in order to gather information about their surroundings. The efficiency of a given WSN is determined by its lifetime. Network lifetime is the duration of time for which it can maintain sensing coverage and network connectivity, which respectively involves the ability to detect an event in a region and to report the sensed data to its destination. In much related work, the network is considered unserviceable the moment when the entire area cannot be fully covered or when the network is not completely connected. However, in many application scenarios, as long as the percentage of disconnected sensor nodes and uncovered areas are above a threshold value, the utility of the network will not be harmed. This latter view will be applied in this thesis. We first derive the probability distribution of the lifetime of a single sensor node by modeling a sensor node as an M/M/ 1 queue which alternates between idle and busy periods. Then, the network connectivity probability is determined by discovering the percentage of sensor nodes that can communicate with the destination given that the monitored region is partially covered. The sensor nodes are randomly deployed in a grid-based network according to the Poisson distribution. Given the average of the number of sensor nodes in a cell, the connectivity probability of two adjacent cells is determined. From this result, we can then derive the probability that a sensor node can communicate with a sink. Finally, the results found for the probability distribution of the lifetime of a single sensor node and the network connectivity probability are integrated to determine the network lifetime

The involvement of phospholipase A₂ (PLA₂ ) in acylation stimulating protein (ASP) signaling /

Preliminary data suggests that the lipogenic factor Acylation Stimulating Protein (ASP), stimulates the activity of calcium-dependent phospholipase A2 (cPLA2) by increasing intracellular calcium levels [Ca2+]i and by activating extracellular-signal-regulated kinase 1/2 (ERK 1/2). The arachidonic acid (AA) generated by cPLA2 action appears to function as a second messenger in ASP signaling.ASP also blocks TG breakdown. The calcium-independent PLA2 (iPLA2) zeta has recently been identified as a novel TG-lipase in 3T3-L1 cells. Bromoenol lactone (BEL), a non-reversible iPLA2 inhibitor, has been shown to specifically inhibit the TG-lipase activity of this enzyme. Preliminary data demonstrates that BEL stimulates basal TG synthesis, likely by inhibiting TG breakdown. The effects of BEL in combination with ASP are non-additive, suggesting they act through the same pathway. Furthermore, ASP appears to inhibit 3H-AA release into the media in a concentration-dependent manner. We propose that ASP inhibits an iPLA2 isoform with TG-lipase activity, an effect that can be mimicked by BEL

Hyperhomocysteinemia Due to Methionine Synthase Deficiency, cblG: Structure of the MTR Gene, Genotype Diversity, and Recognition of a Common Mutation, P1173L

Mutations in the MTR gene, which encodes methionine synthase on human chromosome 1p43, result in the methylcobalamin deficiency G (cblG) disorder, which is characterized by homocystinuria, hyperhomocysteinemia, and hypomethioninemia. To investigate the molecular basis of the disorder, we have characterized the structure of the MTR gene, thereby identifying exon-intron boundaries. This enabled amplification of each of the 33 exons of the gene, from genomic DNA from a panel of 21 patients with cblG. Thirteen novel mutations were identified. These included five deletions (c.12-13delGC, c.381delA, c.2101delT, c.2669-2670delTG, and c.2796-2800delAAGTC) and two nonsense mutations (R585X and E1204X) that would result in synthesis of truncated proteins that lack portions critical for enzyme function. One mutation was identified that resulted in conversion of A to C of the invariant A of the 3′ splice site of intron 9. Five missense mutations (A410P, S437Y, S450H, H595P, and I804T) were identified. The latter mutations, as well as the splice-site mutation, were not detected in a panel of 50 anonymous DNA samples, suggesting that these sequence changes are not polymorphisms present in the general population. In addition, a previously described missense mutation, P1173L, was detected in 16 patients in an expanded panel of 24 patients with cblG. Analysis of haplotypes constructed using sequence polymorphisms identified within the MTR gene demonstrated that this mutation, a C→T transition in a CpG island, has occurred on at least two separate genetic backgrounds

Developing antisense oligonucleotides for a TECPR2 mutation-induced, ultra-rare neurological disorder using patient-derived cellular models

Mutations in the TECPR2 gene are the cause of an ultra-rare neurological disorder characterized by intellectual disability, impaired speech, motor delay, and hypotonia evolving to spasticity, central sleep apnea, and premature death (SPG49 or HSAN9;OMIM: 615031). Little is known about the biological function of TECPR2, and there are currently no available disease-modifying therapies for this disease. Here we describe implementation of an antisense oligonucleotide (ASO) exon-skipping strategy targeting TECPR2 c.1319delT (p.Leu440Argfs*19), a pathogenic variant that results in a premature stop codon within TECPR2 exon 8. We used patient-derived fibroblasts and induced pluripotent stem cell (iPSC)-derived neurons homozygous for the p.Leu440Argfs*19 mutation to model the disease in vitro. Both patient-derived fibroblasts and neurons showed lack of TECPR2 protein expression. We designed and screened ASOs targeting sequences across the TECPR2 exon 8 region to identify molecules that induce exon 8 skipping and thereby remove the premature stop signal. TECPR2 exon 8 skipping restored in-frame expression of a TECPR2 protein variant (TECPR2 Delta Ex8) containing 1,300 of 1,411 amino acids. Optimization of ASO sequences generated a lead candidate (ASO-005-02) with similar to 27 nM potency in patientderived fibroblasts. To examine potential functional rescue induced by ASO-005-02, we used iPSC-derived neurons to analyze the neuronal localization of TECPR2 Delta Ex8 and showed that this form of TECPR2 retains the distinct, punctate neuronal expression pattern of full-length TECPR2. Finally, ASO-005-02 had an acceptable tolerability profile in vivo following a single 20-mg intrathecal dose in cynomolgus monkeys, showing some transient non-adverse behavioral effects with no correlating histopathology. Broad distribution of ASO-005-02 and induction of TECPR2 exon 8 skipping was detected in multiple central nervous system (CNS) tissues, supporting the potential utility of this therapeutic strategy for a subset of patients suffering from this rare disease

Metabolic Activity Determines Efficacy of Macroautophagic Clearance of Pathological Oligomeric α-Synuclein

Macroautophagy is an essential degradative pathway that can be induced to clear aggregated proteins, such as those found in Parkinson’s disease and dementia with Lewy bodies, a form of Parkinsonism. This study found that both LC3-II and beclin were significantly increased in brains from humans with Dementia with Lewy bodies and transgenic mice overexpressing mutant α-synuclein, as compared with respective controls, suggesting that macroautophagy is induced to remove α-syn, particularly oligomeric or mutant forms. Aged mutant animals had higher autophagy biomarker levels relative to younger animals, suggesting that with aging, autophagy is less efficient and requires more stimulation to achieve the same outcome. Disruption of autophagy by RNA interference significantly increased α-syn oligomer accumulation in vitro, confirming the significance of autophagy in α-syn clearance. Finally, rotenone-induced α-syn aggregates were cleared following rapamycin stimulation of autophagy. Chronic rotenone exposure and commensurate reduction of metabolic activity limited the efficacy of rapamycin to promote autophagy, suggesting that cellular metabolism is critical for determining autophagic activity. Cumulatively, these findings support the concept that neuronal autophagy is essential for protein homeostasis and, in our system, reduction of autophagy increased the accumulation of potentially pathogenic α-synuclein oligomers. Aging and metabolic state were identified as important determinants of autophagic activity. This study provides therapeutic and pathological implications for both synucleinopathy and Parkinson’s disease, identifying conditions in which autophagy may be insufficient to degrade α-syn aggregates