Michael G. Lorenz

Friedrich Miescher Laboratory

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Wilfried Wackernagel

Carl von Ossietzky Universität Oldenburg

Kenneth C. Holmes

Canadian Sleep Society

Luis Mengibar-Pozo

Universidad Carlos III de Madrid

Luis Entrena

Universidad Carlos III de Madrid

Raúl Sánchez-Reillo

Universidad Carlos III de Madrid

David Popp

Institute of Molecular and Cell Biology

Luis Mengibar

Universidad Carlos III de Madrid

Gerd Romanowski

Carl von Ossietzky Universität Oldenburg

Claudia Disqué

University Medical Center Utrecht

Wolfgang E. Krumbein

Carl von Ossietzky Universität Oldenburg

Cooperative Institutions

Max Planck Society

Carl von Ossietzky Universität Oldenburg

Universidad Carlos III de Madrid

Friedrich Miescher Laboratory

University of Oxford

National Institutes of Health

RWTH Aachen University

Centre for Human Genetics

Max Planck Institute for Medical Research

National Cancer Institute

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Low-power design in aerospace circuits: A case study

IEEE Aerospace and Electronic Systems Magazine (2013)

Luis Mengibar-Pozo Michael G. Lorenz Celia López Luis Entrena

The results of applying low-power design techniques to a circuit used in a space application have been presented. The design used for the experiments was implemented in an antifuse FPGA (ACTEL RT14100A). Power consumption was first estimated by simulation of the design to identify the elements that had a higher impact on the total power consumption. According to the power estimations, the more suitable power reduction techniques were identified and applied to reduce power consumption of the initial design. With this approach, the worst-case power consumption was reduced to 30% of the original power estimations by using gated clocks and redesigning small critical components with an asynchronous style. Further reduction, typically up to 16% of the original value, was possible by applying architectural modifications. These results show that important power savings are possible for FPGA designs by following the appropriate methodology. Precise estimation of the contribution of the various functional units to the total power is essential to target only those modifications that are significant from the power point of view and to avoid large redesign efforts.

Power analysis

Design space exploration

Dynamic demand

Low-power electronics

10.1109/maes.2013.6693668

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Citations (2)

Adsorption of plasmid DNA to mineral surfaces and protection against DNase I

Applied and Environmental Microbiology (1991)

Gerd Romanowski Michael G. Lorenz Wilfried Wackernagel

The adsorption of [3H]thymidine-labeled plasmid DNA (pHC314; 2.4 kb) of different conformations to chemically pure sand was studied in a flowthrough microenvironment. The extent of adsorption was affected by the concentration and valency of cations, indicating a charge-dependent process. Bivalent cations (Mg2+, Ca2+) were 100-fold more effective than monovalent cations (Na+, K+, NH4+). Quantitative adsorption of up to 1 microgram of negatively supercoiled or linearized plasmid DNA to 0.7 g of sand was observed in the presence of 5 mM MgCl2 at pH 7. Under these conditions, more than 85% of DNA adsorbed within 60 s. Maximum adsorption was 4 micrograms of DNA to 0.7 g of sand. Supercoil molecules adsorbed slightly less than linearized or open circular plasmids. An increase of the pH from 5 to 9 decreased adsorption at 0.5 mM MgCl2 about eightfold. It is concluded that adsorption of plasmid DNA to sand depends on the neutralization of negative charges on the DNA molecules and the mineral surfaces by cations. The results are discussed on the grounds of the polyelectrolyte adsorption model. Sand-adsorbed DNA was 100 times more resistant against DNase I than was DNA free in solution. The data support the idea that plasmid DNA can enter the extracellular bacterial gene pool which is located at mineral surfaces in natural bacterial habitats.

Plasmid preparation

10.1128/aem.57.4.1057-1061.1991

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Citations (332)

Bacterial gene transfer by natural genetic transformation in the environment.

Microbiological Reviews (1994)

Michael G. Lorenz Wilfried Wackernagel

Natural genetic transformation is the active uptake of free DNA by bacterial cells and the heritable incorporation of its genetic information. Since the famous discovery of transformation in Streptococcus pneumoniae by Griffith in 1928 and the demonstration of DNA as the transforming principle by Avery and coworkers in 1944, cellular processes involved in transformation have been studied extensively by in vitro experimentation with a few transformable species. Only more recently has it been considered that transformation may be a powerful mechanism of horizontal gene transfer in natural bacterial populations. In this review the current understanding of the biology of transformation is summarized to provide the platform on which aspects of bacterial transformation in water, soil, and sediments and the habitat of pathogens are discussed. Direct and indirect evidence for gene transfer routes by transformation within species and between different species will be presented, along with data suggesting that plasmids as well as chromosomal DNA are subject to genetic exchange via transformation. Experiments exploring the prerequisites for transformation in the environment, including the production and persistence of free DNA and factors important for the uptake of DNA by cells, will be compiled, as well as possible natural barriers to transformation. The efficiency of gene transfer by transformation in bacterial habitats is possibly genetically adjusted to submaximal levels. The fact that natural transformation has been detected among bacteria from all trophic and taxonomic groups including archaebacteria suggests that transformability evolved early in phylogeny. Probable functions of DNA uptake other than gene acquisition will be discussed. The body of information presently available suggests that transformation has a great impact on bacterial population dynamics as well as on bacterial evolution and speciation.

Gene transfer

Horizontal Gene Transfer

10.1128/mmbr.58.3.563-602.1994

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Citations (543)

Release of transforming plasmid and chromosomal DNA from two cultured soil bacteria

Archives of Microbiology (1991)

Michael G. Lorenz Detlef Gerjets Wilfried Wackernagel

Plasmid preparation

Exogenous DNA

Acinetobacter calcoaceticus

10.1007/bf00263005

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Citations (123)

Small steps toward membrane distillation commercialization

SPIE Newsroom (2007)

Michael G. Lorenz

Membrane distillation (MD)1 is a relatively new process that is under investigation worldwide as a low cost, energy saving alternative to conventional separation processes such as distillation and reverse osmosis. MD has many advantages compared to other, more popular separation processes. It works at room conditions (pressure and temperature), and low-grade, waste, and/or alternative energy sources such as solar and geothermal can be used to power it. MD exhibits a very high level of rejection with inorganic solutions, and the necessary equipment is small. Furthermore, since the process appeared in the late 1960s, proponents have claimed that would be cost effective. As such, it has been studied by academic experimentalists and theoreticians around the world. In industry, however, MD has gained little acceptance and is yet to be implemented. The major barriers to commercialization includeMDmembrane andmodule design, membrane pore wetting, low permeate flow rate and flux decay, and uncertain energetic and economic costs. The driving force in MD processes is the vapor pressure difference across the membrane, which results from an imposed temperature difference. The lower vapor pressure on the permeate side can be set up in various ways: direct contact MD (DCMD),2 osmotic MD,3 sweeping gas MD,4 vacuumMD,5 and air gap MD.6, 7 Our research focuses on the investigation and optimization of DCMD. In this process, a hot solution (feed) is brought into contact with one side of the membrane and a cold solution (permeate) into contact with the other, so that the vapor pressure is different on each side of the membrane. This pressure difference drives the vapor through themembrane pores, and then the vapor condenses in contact with the cold solution on the other side. The hydrophobic nature of themembrane prevents the penetration of the liquid solution into the pores unless a pressure higher than the so-called liquid entry pressure is applied. This Figure 1. Experimental setup. The two double-wall reservoirs contain the feed and permeate solutions. Both variable flow gear pumps drive both solutions. Liquid flow sensors set at the inlet and outlet of each semicell measure the flow rate. Digital pressure transducers and PT100 temperature probes measure the pressure and temperature on both sides of the membrane. Thermostats and heat exchangers connected to the reservoirs controll the temperature.

Membrane Distillation

10.1117/2.1200706.0733

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Citations (2)

Engineering Proteases for Industrial Applications

Ljubica Vojcic Felix Jakob Ronny Martínez Hendrik Hellmuth Timothy D. O’Connell

Proteases play a key role in many physiological processes, such as maturation of proenzymes and hormones, protein hydrolysis in the extracellular environment blood clotting, processing and transport of secretory proteins across membranes, and as pathogenic factors. Besides their importance in physiology, proteases have a high relevance in technical enzymatic applications. In particular, extracellular proteases represent approximately 40% of the total enzymes sales in waste management, food, detergent, leather, diagnostics, and pharmaceutical industries. The use of proteolytic agents in detergent industry is the most prominent application of subtilisins in terms of market volume and tonnage. The incorporation of enzymes, especially subtilisin proteases, into laundry detergents is an ongoing challenge for the detergent industry. Nowadays, enzymes are encapsulated by several layers consisting of carboxymethyl cellulose or similar protective colloids. As attractive enzymes for laundry applications, subtilisins have been studied and reengineered toward increased resistance against oxidative bleaching agents.

Subtilisin

Proteolytic enzymes

10.1002/9783527677122.ch6

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Citations (4)

Polymerase chain reaction detection of sepsis-inducing pathogens in blood using SepsiTest™

Critical Care (2008)

Claudia Disqué Anna-Julia Kochem Helge Mühl Michael G. Lorenz Samir G. Sakka

BackgroundThe morbidity and mortality from severe sepsis depends largely on how quickly and comprehensively evidencebased therapies are administered.As such, a huge opportunity exists.However, optimal care requires not only factual knowledge, but also numerous practical strategies including the ability to recognize a disease, to identify impending crises, to communicate effectively, to run a team, to work under stress and to simultaneously coordinate multiple tasks.Medical simulation offers a way to practice these essential crisis management skills, and without any risk to patients.Methods Following a didactic lecture on the key components of the Surviving Sepsis Campaign Guidelines, we trained 20 emergency medicine residents on a portable Laerdal Patient Simulator.Pre-programmed sepsis scenarios were developed following a needs assessment and modified Delphi technique.To maximize realism, this was performed in the acute care area of the Emergency Department and included a pre-briefed respiratory therapist and nurse.We videotaped resident performance and provided nonpunitive feedback, focusing on the comprehensiveness of therapy (for example, whether broad-spectrum antibiotics were given) and crisis resource management strategies (for example, whether help was asked for and tasks were appropriately allocated).Results Evaluation using a five-point Likert scale demonstrated that participants found this very useful (4.5/5), that lessons were complementary and supplementary to those learned from lectures (4.5/5) and that medical simulation was realistic (4/5).In addition, despite prior sepsis lectures, comparison of pre-tests and posttests showed that more emergency medicine residents would: administer broad-spectrum antibiotics as soon as possible following hypotension (14/20 pre-test, compared with 16/20 posttest), administer low-dose corticosteroids for those with refractory shock (10/20 pre-test, compared with 13/20 post-test), and would favour norepinephrine as a vasopressor (8/20 pre-test, compared with 12/20 post-test).Participants specifically valued the chance to observe and practice crisis resource management skills, which they felt had not been previously addressed (19/20).Conclusion Medical simulation appears to be an effective way to change both knowledge and behaviours in the treatment of severe sepsis.Many education and licensing boards also expect trainees to become not only content experts, but also effective communicators, collaborators, resource managers and advocates.These laudable goals are difficult to capture with traditional lectures but are comparably easy using medical simulation.We hope others will consider medical simulation as a complementary teaching and quality-assurance strategy in the fight against sepsis.

10.1186/cc7043

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Citations (3)

A Comparison of the Atomic Model of F-Actin with Cryo-Electron Micrographs of Actin and Decorated Actin

Advances in experimental medicine and biology (1993)

Kenneth C. Holmes Monique M. Tirion David Popp Michael G. Lorenz Wolfgang Kabsch

Atomic model

Tropomyosin

Cryo-Electron Microscopy

Actin-binding protein

Electron micrographs

10.1007/978-1-4615-2872-2_2

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Citations (23)

The extracellular nuclease of Serratia marcescens: studies on the activity in vitro and effect on transforming DNA in a groundwater aquifer microcosm

Archives of Microbiology (1994)

Ingrid Ahrenholtz Michael G. Lorenz Wilfried Wackernagel

Microcosm

Nuclease

10.1007/bf00276480

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Citations (30)

Influence of Leaching Parameters on the Biological Removal of Uranium from Coal by a Filamentous Cyanobacterium

Applied and Environmental Microbiology (1985)

Michael G. Lorenz Wolfgang E. Krumbein

Axenic cultures of the filamentous cyanobacterium LPP OL3 were incubated with samples of uraniumbearing coal from a German mining area. The influence of leaching parameters such as coal concentration (pulp density), initial biomass, particle size, temperature, and composition of the growth medium on the leaching of uranium from the ore by the cyanobacterial strain was studied. When low pulp densities were applied, the yield of biologically extracted uranium was optimal (reaching 96% at 1% [wt/vol] coal) and all released uranium was found in the culture liquid. Above 10% (wt/vol) coal in the medium, the amount of cell-bound uranium increased. Initial biomass concentration (protein content of the cultures) and particle size were not critical parameters of leaching by LPP OL3. However, temperature and composition of the growth medium profoundly influenced the leaching of uranium and growth of the cyanobacterium. The yield of leached uranium (at 10% [wt/vol] coal) could not be raised with a tank leaching apparatus. Also, coal ashes were not suitable substrates for the leaching of uranium by LPP OL3. In conclusion, the reactions of the cyanobacterium to variations in leaching parameters were different from reactions of acidic leaching organisms.

10.1128/aem.50.5.1296-1300.1985

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Citations (2)