Theoretische und praktische Untersuchung zur Zeit- und Frequenzanalyse zeitkontinuierlicher und zeitdiskreter Systeme

Im Rahmen dieser Bachelorarbeit wird der Zusammenhang zwischen dem Zeitbereich und dem Frequenzbereich zeitkontinuierlicher und zeitdiskreter Systeme beschrieben. Anhand der untersuchten theoretischen Grundlagen der zeitdiskreten Systeme wird mithilfe der Layout-Software „Kicad“ eine Leiterplatte implementiert, die als zeitdiskretes Tiefpassfilter oder zeitdiskretes Bandpassfilter Anwendung findet

Pharmacological Modulation of Rate-Dependent Depression of the Spinal H-Reflex Predicts Therapeutic Efficacy against Painful Diabetic Neuropathy.

Impaired rate-dependent depression (RDD) of the spinal H-reflex occurs in diabetic rodents and a sub-set of patients with painful diabetic neuropathy. RDD is unaffected in animal models of painful neuropathy associated with peripheral pain mechanisms and diabetic patients with painless neuropathy, suggesting RDD could serve as a biomarker for individuals in whom spinal disinhibition contributes to painful neuropathy and help identify therapies that target impaired spinal inhibitory function. The spinal pharmacology of RDD was investigated in normal rats and rats after 4 and 8 weeks of streptozotocin-induced diabetes. In normal rats, dependence of RDD on spinal GABAergic inhibitory function encompassed both GABAA and GABAB receptor sub-types. The time-dependent emergence of impaired RDD in diabetic rats was preceded by depletion of potassium-chloride co-transporter 2 (KCC2) protein in the dorsal, but not ventral, spinal cord and by dysfunction of GABAA receptor-mediated inhibition. GABAB receptor-mediated spinal inhibition remained functional and initially compensated for loss of GABAA receptor-mediated inhibition. Administration of the GABAB receptor agonist baclofen restored RDD and alleviated indices of neuropathic pain in diabetic rats, as did spinal delivery of the carbonic anhydrase inhibitor acetazolamide. Pharmacological manipulation of RDD can be used to identify potential therapies that act against neuropathic pain arising from spinal disinhibition

Pharmacological Modulation of Rate-Dependent Depression of the Spinal H-Reflex Predicts Therapeutic Efficacy against Painful Diabetic Neuropathy

Impaired rate-dependent depression (RDD) of the spinal H-reflex occurs in diabetic rodents and a sub-set of patients with painful diabetic neuropathy. RDD is unaffected in animal models of painful neuropathy associated with peripheral pain mechanisms and diabetic patients with painless neuropathy, suggesting RDD could serve as a biomarker for individuals in whom spinal disinhibition contributes to painful neuropathy and help identify therapies that target impaired spinal inhibitory function. The spinal pharmacology of RDD was investigated in normal rats and rats after 4 and 8 weeks of streptozotocin-induced diabetes. In normal rats, dependence of RDD on spinal GABAergic inhibitory function encompassed both GABAA and GABAB receptor sub-types. The time-dependent emergence of impaired RDD in diabetic rats was preceded by depletion of potassium-chloride co-transporter 2 (KCC2) protein in the dorsal, but not ventral, spinal cord and by dysfunction of GABAA receptor-mediated inhibition. GABAB receptor-mediated spinal inhibition remained functional and initially compensated for loss of GABAA receptor-mediated inhibition. Administration of the GABAB receptor agonist baclofen restored RDD and alleviated indices of neuropathic pain in diabetic rats, as did spinal delivery of the carbonic anhydrase inhibitor acetazolamide. Pharmacological manipulation of RDD can be used to identify potential therapies that act against neuropathic pain arising from spinal disinhibition

A Maternal-Zygotic Effect Gene, Zfp57, Maintains Both Maternal and Paternal Imprints

SummaryThe mechanisms responsible for maintaining genomic methylation imprints in mouse embryos are not understood. We generated a knockout mouse in the Zfp57 locus encoding a KRAB zinc finger protein. Loss of just the zygotic function of Zfp57 causes partial neonatal lethality, whereas eliminating both the maternal and zygotic functions of Zfp57 results in a highly penetrant embryonic lethality. In oocytes, absence of Zfp57 results in failure to establish maternal methylation imprints at the Snrpn imprinted region. Intriguingly, methylation imprints are reacquired specifically at the maternally derived Snrpn imprinted region when the zygotic Zfp57 is present in embryos. This suggests that there may be DNA methylation-independent memory for genomic imprints. Zfp57 is also required for the postfertilization maintenance of maternal and paternal methylation imprints at multiple imprinted domains. The effects on genomic imprinting are consistent with the maternal-zygotic lethality of Zfp57 mutants

Immune Response of A Novel ATR-AP205-001 Conjugate Anti-hypertensive Vaccine

Abstract We developed a virus-like particle (VLP)-based therapeutic vaccine against angiotensin II receptor type 1, ATR-AP205-001, which could significantly reduce the blood pressure and protect target organs of hypertensive animals. In this study, we focused on the immunological effect and safety of the VLP-based vaccine. By comparing to the depolymerized dimeric vaccine ATR-Dimer-001, we found that ATR-AP205-001 reached subcapsular sinus of lymph node shortly after administration, followed by accumulation on follicle dendritic cells via follicle B cell transportation, while ATR-Dimer-001 vaccine showed no association with FDCs. ATR-AP205-001 vaccine strongly activated dendritic cells, which promoted T cells differentiation to follicular helper T cells. ATR-AP205-001 vaccine induced powerful germinal center reaction, which was translated to a boost of specific antibody production and long-lasting B cell memory, far superior to ATR-Dimer-001 vaccine. Moreover, neither cytotoxic T cells, nor Th1/Th17 cell-mediated inflammation was observed in ATR-AP205-001 vaccine, similar to ATR-Dimer-001 vaccine. We concluded that ATR-AP205-001 vaccine quickly induced potent humoral immunity through collaboration of B cells, follicular dendritic cells and follicular helper T cells, providing an effective and safe intervention for hypertension in the future clinical application

Mapping protein direct interactome of oxidoreductases with small molecular chemical cross-linkers in live cells

Identifying direct substrates of enzymes has been a long-term challenge. Here, we present a strategy using live cell chemical cross-linking and mass spectrometry to identify the putative substrates of enzymes for further biochemical validation. Compared with other methods, our strategy is based on the identification of cross-linked peptides supported by high-quality MS/MS spectra, which eliminates false-positive discoveries of indirect binders. Additionally, cross-linking sites allow the analysis of interaction interfaces, providing further information for substrate validation. We demonstrated this strategy by identifying direct substrates of thioredoxin in both E. coli and HEK293T cells using two bis-vinyl sulfone chemical cross-linkers BVSB and PDES. We confirmed that BVSB and PDES have high specificity in cross-linking the active site of thioredoxin with its substrates both in vitro and in live cells. Applying live cell cross-linking, we identified 212 putative substrates of thioredoxin in E. coli and 299 putative S-nitrosylation (SNO) substrates of thioredoxin in HEK293T cells. In addition to thioredoxin, we have shown that this strategy can be applied to other proteins in the thioredoxin superfamily. Based on these results, we believe future development of cross-linking techniques will further advance cross-linking mass spectrometry in identifying substrates of other classes of enzymes

Insulin-like growth factor-1 activates AMPK to augment mitochondrial function and correct neuronal metabolism in sensory neurons in type 1 diabetes

Objective: Diabetic sensorimotor polyneuropathy (DSPN) affects approximately half of diabetic patients leading to significant morbidity. There is impaired neurotrophic growth factor signaling, AMP-activated protein kinase (AMPK) activity and mitochondrial function in dorsal root ganglia (DRG) of animal models of type 1 and type 2 diabetes. We hypothesized that sub-optimal insulin-like growth factor 1 (IGF-1) signaling in diabetes drives loss of AMPK activity and mitochondrial function, both contributing to development of DSPN. Methods: Age-matched control Sprague-Dawley rats and streptozotocin (STZ)-induced type 1 diabetic rats with/without IGF-1 therapy were used for in vivo studies. For in vitro studies, DRG neurons from control and STZ-diabetic rats were cultured and treated with/without IGF-1 in the presence or absence of inhibitors or siRNAs. Results: Dysregulation of mRNAs for IGF-1, AMPKα2, ATP5a1 (subunit of ATPase), and PGC-1β occurred in DRG of diabetic vs. control rats. IGF-1 up-regulated mRNA levels of these genes in cultured DRGs from control or diabetic rats. IGF-1 treatment of DRG cultures significantly (P < 0.05) increased phosphorylation of Akt, P70S6K, AMPK and acetyl-CoA carboxylase (ACC). Mitochondrial gene expression and oxygen consumption rate (spare respiratory capacity), ATP production, mtDNA/nDNA ratio and neurite outgrowth were augmented (P < 0.05). AMPK inhibitor, Compound C, or AMPKα1-specific siRNA suppressed IGF-1 elevation of mitochondrial function, mtDNA and neurite outgrowth. Diabetic rats treated with IGF-1 exhibited reversal of thermal hypoalgesia and, in a separate study, reversed the deficit in corneal nerve profiles. In diabetic rats, IGF-1 elevated the levels of AMPK and P70S6K phosphorylation, raised Complex IV-MTCO1 and Complex V-ATP5a protein expression, and restored the enzyme activities of Complex IV and I in the DRG. IGF-1 prevented TCA metabolite build-up in nerve. Conclusions: In DRG neuron cultures IGF-1 signals via AMPK to elevate mitochondrial function and drive axonal outgrowth. We propose that this signaling axis mediates IGF-1-dependent protection from distal dying-back of fibers in diabetic neuropathy. Keywords: IGF-1, AMPK, Axon regeneration, Diabetic neuropathy, Oxygen consumption rat