Lukas Nel - Academia.edu (original) (raw)
Papers by Lukas Nel
Proceedings of The National Academy of Sciences
Animals. Care and use of the animals and the experimental protocol were reviewed and approved by ... more Animals. Care and use of the animals and the experimental protocol were reviewed and approved by the animal welfare commissioner and the regional board for scientific animal experiments in Tübingen.
Ca 2ϩ channel inactivation was investigated in neurohypophysial nerve terminals by using patch-cl... more Ca 2ϩ channel inactivation was investigated in neurohypophysial nerve terminals by using patch-clamp techniques. The contribution of intracellular Ca 2ϩ to inactivation was evaluated by replacing Ca 2ϩ with Ba 2ϩ or by including BAPTA in the internal recording solution. Ca 2ϩ channel inactivation during depolarizing pulses was primarily voltage-dependent. A contribution of intracellular Ca 2ϩ was revealed by comparing steadystate inactivation of Ca 2ϩ channels with Ca 2ϩ current and with intracellular [Ca 2ϩ ]. However, this contribution was small compared to that of voltage. In contrast to voltage-gated Ca 2ϩ channels in other preparations, in the neurohypophysis Ba 2ϩ substitution or intracellular BAPTA increased the speed of inactivation while reducing the steady-state level of inactivation. Ca 2ϩ channel recovery from inactivation was studied by using a paired-pulse protocol. The rate of Ca 2ϩ channel recovery from inactivation at negative potentials was increased dramatically by Ba 2ϩ substitution or intracellular BAPTA, indicating
With the recent development in nanoscience and nanotechnology, there is a pressing demand for ass... more With the recent development in nanoscience and nanotechnology, there is a pressing demand for assessment of the potential hazards of carbon nanomaterials to humans and other biological systems. This chapter summarizes our recent in vitro cytotoxicity and genotoxicity studies on carbon nanomaterials with an emphasis on carbon nanotubes and nanodiamonds. The studies summarized in this chapter demonstrate that carbon nanomaterials exhibit material-specific and cell-specific cytotoxicity with the general trend for biocompatibility: nanodiamonds > carbon black powders > multiwalled carbon nanotubes > single-walled carbon nanotubes, with macrophages being much more sensitive to the cytotoxicity of these carbon nanomaterials than neuroblastoma cells. However, the cytotoxicity to carbon nanomaterials could be tuned by functionalizing the nanomaterials with different surface groups. Multiwalled carbon nanotubes and nanodiamonds, albeit to a less extend, can accumulate in mouse embryonic stem (ES) cells to cause DNA damage through reactive oxygen species (ROS) generation and to increase the mutation frequency in mouse ES cells. These results point out the great need for careful scrutiny of the toxicity of nanomaterials at the molecular level, or genotoxicity, even for those materials like multiwalled carbon nanotubes and nanodiamonds that have been demonstrated to cause limited or no toxicity at the cellular level.
International Journal of Human Genetics, 2007
Exposure to ambient air pollution (particles, fibres) is associated with pulmonary diseases and c... more Exposure to ambient air pollution (particles, fibres) is associated with pulmonary diseases and cancer. The mechanisms of induced health effects are believed to involve inflammation and oxidative stress. Oxidative stress mediated by airborne particles and/or fibres may arise from direct generation of reactive oxygen species (ROS) from the surface of particles/fibres, soluble compounds such as transition metals or organic compounds, and activation of inflammatory cells capable of generating ROS and reactive nitrogen species (RNS). Generation of ROS/RNS can directly cause covalent modifications to DNA or they can initiate the formation of genotoxic lipid hydroperoxides. The resulting oxidative DNA damage can lead to changed gene expression such as upregulation of tumor promoters and downregulation of tumor suppressor genes and thus may be implicated in cancer development. The present review describes the important role of free radicals in particle-/fibreinduced cellular damage, the interaction of ROS with target molecules, especially with DNA, and the modulation of specific genes and transcription factor caused by oxidative stress.
© 2 0 0 1 C a n c e r R e s e a r c h C a m p a i g n Summary An expert working group of the Euro... more © 2 0 0 1 C a n c e r R e s e a r c h C a m p a i g n Summary An expert working group of the European Association for Palliative Care has revised and updated its guidelines on the use of morphine in the management of cancer pain. The revised recommendations presented here give guidance on the use of morphine and the alternative strong opioid analgesics which have been introduced in many parts of the world in recent years. Practical strategies for dealing with difficult situations are described presenting a consensus view where supporting evidence is lacking. The strength of the evidence on which each recommendation is based is indicated.
Ibis, 2008
The bulk ore carrier Apollo Seasank near Dassen Island, South Africa, on 20 June 1994 during a pe... more The bulk ore carrier Apollo Seasank near Dassen Island, South Africa, on 20 June 1994 during a period of winter storms. Approximately 10 000 African (Jackass) Penguins Spheniscus demersuswere oiled, collected and transported to the SANCCOB rescue centre; 5213 were released after cleaning, 4076 with flipper bands. We believe that most of the penguins oiled during this incident reached an island or the mainland alive, and that there was no mass mortality in the wild at the time of the oil spill. Birds from all parts of the breeding range were oiled, but most were from Robben and Dassen Islands. The overwhelming majority of released birds made the transition from the rescue centre to the wild successfully; 2652 had been resighted at breeding colonies within two years of their release; the cumulative number of birds was increasing steadily and an asymptote had not been reached by August 1996. There was a wide dispersal of released penguins, with recoveries and resightings over 1800 km of coastline between Algoa Bay and Walvis Bay.
Nell'ambito del progetto internazionale di ricerca GIANO (acronimo di Grafica Innovativa per il p... more Nell'ambito del progetto internazionale di ricerca GIANO (acronimo di Grafica Innovativa per il patrimonio Artistico Nazionale e per l'Occupazione giovanile), promosso e coordinato dall'ENEA di Bologna, è stato realizzato un sistema informatico prototipale per la gestione e la fruizione di decorazioni musive. Il progetto si è posto, come obiettivo principale, quello di sfruttare le potenzialità insite nelle più progredite tecniche matematiche ed informatiche, nelle attuali metodologie di elaborazione di immagini e simulazione di realtà virtuale, per lo studio e la divulgazione di tali beni.
Steroids, in addition to regulating gene expression, directly affect a variety of ion channels. W... more Steroids, in addition to regulating gene expression, directly affect a variety of ion channels. We examined the action of steroids on human embryonic kidney 293 cells stably transfected to express rat ␣42 neuronal nicotinic receptors. Each steroid that was tested inhibited acetylcholine responses from these receptors, with slow kinetics requiring seconds for block to develop and recover. The action of one steroid [3␣,5␣,17-3-hydroxyandrostane-17-carbonitrile (ACN)] was studied in detail. Block showed enantioselectivity, with an IC 50 value of 1.5 M for ACN and 4.5 M for the enantiomer. Inhibition curves had Hill slopes larger than 1, indicating more than one binding site per receptor. Block did not require intracellular compounds containing high-energy phosphate bonds and was not affected by analogs of GTP, suggesting that the mechanism does not
Network processors are ideally suited as implementation platforms for active and programmable net... more Network processors are ideally suited as implementation platforms for active and programmable networks. Thus, an active network node OS needs to support network processors as well as traditional processor architectures. Resource control in a node OS is required for the accounting and charging of resource consumption to a customer. Resources consumed by services composed of kernel and user space components need to be controlled. In this paper, we describe the architecture and design of PromethOS, a flexible node OS based on the Linux kernel. PromethOS provides mechanisms for the installation, configuration, operation and removal of untrusted code modules at run-time in kernel and in user space and on specialized engines of network processors. Resource control facilities provide for node stability and allow for several customized services running in parallel in a safe and reliable way. We introduce the concept of a module chain to realize a dynamically configurable communication infrastructure, allowing for communication between code modules and different protection domains. Since PromethOS is based on Linux, it may easily be deployed on traditional processors and network processor architectures.
Don't believe in war lad, you can never win a fight. War constricts the heart lad, a pair of boot... more Don't believe in war lad, you can never win a fight. War constricts the heart lad, a pair of boots too tight. Your mighty horses swift and true will be no use at all, exposed on a giant's palm, beneath musket shot you'll fall.
Proceedings of The National Academy of Sciences
Animals. Care and use of the animals and the experimental protocol were reviewed and approved by ... more Animals. Care and use of the animals and the experimental protocol were reviewed and approved by the animal welfare commissioner and the regional board for scientific animal experiments in Tübingen.
Ca 2ϩ channel inactivation was investigated in neurohypophysial nerve terminals by using patch-cl... more Ca 2ϩ channel inactivation was investigated in neurohypophysial nerve terminals by using patch-clamp techniques. The contribution of intracellular Ca 2ϩ to inactivation was evaluated by replacing Ca 2ϩ with Ba 2ϩ or by including BAPTA in the internal recording solution. Ca 2ϩ channel inactivation during depolarizing pulses was primarily voltage-dependent. A contribution of intracellular Ca 2ϩ was revealed by comparing steadystate inactivation of Ca 2ϩ channels with Ca 2ϩ current and with intracellular [Ca 2ϩ ]. However, this contribution was small compared to that of voltage. In contrast to voltage-gated Ca 2ϩ channels in other preparations, in the neurohypophysis Ba 2ϩ substitution or intracellular BAPTA increased the speed of inactivation while reducing the steady-state level of inactivation. Ca 2ϩ channel recovery from inactivation was studied by using a paired-pulse protocol. The rate of Ca 2ϩ channel recovery from inactivation at negative potentials was increased dramatically by Ba 2ϩ substitution or intracellular BAPTA, indicating
With the recent development in nanoscience and nanotechnology, there is a pressing demand for ass... more With the recent development in nanoscience and nanotechnology, there is a pressing demand for assessment of the potential hazards of carbon nanomaterials to humans and other biological systems. This chapter summarizes our recent in vitro cytotoxicity and genotoxicity studies on carbon nanomaterials with an emphasis on carbon nanotubes and nanodiamonds. The studies summarized in this chapter demonstrate that carbon nanomaterials exhibit material-specific and cell-specific cytotoxicity with the general trend for biocompatibility: nanodiamonds > carbon black powders > multiwalled carbon nanotubes > single-walled carbon nanotubes, with macrophages being much more sensitive to the cytotoxicity of these carbon nanomaterials than neuroblastoma cells. However, the cytotoxicity to carbon nanomaterials could be tuned by functionalizing the nanomaterials with different surface groups. Multiwalled carbon nanotubes and nanodiamonds, albeit to a less extend, can accumulate in mouse embryonic stem (ES) cells to cause DNA damage through reactive oxygen species (ROS) generation and to increase the mutation frequency in mouse ES cells. These results point out the great need for careful scrutiny of the toxicity of nanomaterials at the molecular level, or genotoxicity, even for those materials like multiwalled carbon nanotubes and nanodiamonds that have been demonstrated to cause limited or no toxicity at the cellular level.
International Journal of Human Genetics, 2007
Exposure to ambient air pollution (particles, fibres) is associated with pulmonary diseases and c... more Exposure to ambient air pollution (particles, fibres) is associated with pulmonary diseases and cancer. The mechanisms of induced health effects are believed to involve inflammation and oxidative stress. Oxidative stress mediated by airborne particles and/or fibres may arise from direct generation of reactive oxygen species (ROS) from the surface of particles/fibres, soluble compounds such as transition metals or organic compounds, and activation of inflammatory cells capable of generating ROS and reactive nitrogen species (RNS). Generation of ROS/RNS can directly cause covalent modifications to DNA or they can initiate the formation of genotoxic lipid hydroperoxides. The resulting oxidative DNA damage can lead to changed gene expression such as upregulation of tumor promoters and downregulation of tumor suppressor genes and thus may be implicated in cancer development. The present review describes the important role of free radicals in particle-/fibreinduced cellular damage, the interaction of ROS with target molecules, especially with DNA, and the modulation of specific genes and transcription factor caused by oxidative stress.
© 2 0 0 1 C a n c e r R e s e a r c h C a m p a i g n Summary An expert working group of the Euro... more © 2 0 0 1 C a n c e r R e s e a r c h C a m p a i g n Summary An expert working group of the European Association for Palliative Care has revised and updated its guidelines on the use of morphine in the management of cancer pain. The revised recommendations presented here give guidance on the use of morphine and the alternative strong opioid analgesics which have been introduced in many parts of the world in recent years. Practical strategies for dealing with difficult situations are described presenting a consensus view where supporting evidence is lacking. The strength of the evidence on which each recommendation is based is indicated.
Ibis, 2008
The bulk ore carrier Apollo Seasank near Dassen Island, South Africa, on 20 June 1994 during a pe... more The bulk ore carrier Apollo Seasank near Dassen Island, South Africa, on 20 June 1994 during a period of winter storms. Approximately 10 000 African (Jackass) Penguins Spheniscus demersuswere oiled, collected and transported to the SANCCOB rescue centre; 5213 were released after cleaning, 4076 with flipper bands. We believe that most of the penguins oiled during this incident reached an island or the mainland alive, and that there was no mass mortality in the wild at the time of the oil spill. Birds from all parts of the breeding range were oiled, but most were from Robben and Dassen Islands. The overwhelming majority of released birds made the transition from the rescue centre to the wild successfully; 2652 had been resighted at breeding colonies within two years of their release; the cumulative number of birds was increasing steadily and an asymptote had not been reached by August 1996. There was a wide dispersal of released penguins, with recoveries and resightings over 1800 km of coastline between Algoa Bay and Walvis Bay.
Nell'ambito del progetto internazionale di ricerca GIANO (acronimo di Grafica Innovativa per il p... more Nell'ambito del progetto internazionale di ricerca GIANO (acronimo di Grafica Innovativa per il patrimonio Artistico Nazionale e per l'Occupazione giovanile), promosso e coordinato dall'ENEA di Bologna, è stato realizzato un sistema informatico prototipale per la gestione e la fruizione di decorazioni musive. Il progetto si è posto, come obiettivo principale, quello di sfruttare le potenzialità insite nelle più progredite tecniche matematiche ed informatiche, nelle attuali metodologie di elaborazione di immagini e simulazione di realtà virtuale, per lo studio e la divulgazione di tali beni.
Steroids, in addition to regulating gene expression, directly affect a variety of ion channels. W... more Steroids, in addition to regulating gene expression, directly affect a variety of ion channels. We examined the action of steroids on human embryonic kidney 293 cells stably transfected to express rat ␣42 neuronal nicotinic receptors. Each steroid that was tested inhibited acetylcholine responses from these receptors, with slow kinetics requiring seconds for block to develop and recover. The action of one steroid [3␣,5␣,17-3-hydroxyandrostane-17-carbonitrile (ACN)] was studied in detail. Block showed enantioselectivity, with an IC 50 value of 1.5 M for ACN and 4.5 M for the enantiomer. Inhibition curves had Hill slopes larger than 1, indicating more than one binding site per receptor. Block did not require intracellular compounds containing high-energy phosphate bonds and was not affected by analogs of GTP, suggesting that the mechanism does not
Network processors are ideally suited as implementation platforms for active and programmable net... more Network processors are ideally suited as implementation platforms for active and programmable networks. Thus, an active network node OS needs to support network processors as well as traditional processor architectures. Resource control in a node OS is required for the accounting and charging of resource consumption to a customer. Resources consumed by services composed of kernel and user space components need to be controlled. In this paper, we describe the architecture and design of PromethOS, a flexible node OS based on the Linux kernel. PromethOS provides mechanisms for the installation, configuration, operation and removal of untrusted code modules at run-time in kernel and in user space and on specialized engines of network processors. Resource control facilities provide for node stability and allow for several customized services running in parallel in a safe and reliable way. We introduce the concept of a module chain to realize a dynamically configurable communication infrastructure, allowing for communication between code modules and different protection domains. Since PromethOS is based on Linux, it may easily be deployed on traditional processors and network processor architectures.
Don't believe in war lad, you can never win a fight. War constricts the heart lad, a pair of boot... more Don't believe in war lad, you can never win a fight. War constricts the heart lad, a pair of boots too tight. Your mighty horses swift and true will be no use at all, exposed on a giant's palm, beneath musket shot you'll fall.