Commemorates heyday period in the 1920s
FRANKFURT. The 1920s were the golden age of quantum mechanics. Brilliant theoreticians and young, innovative thinkers poured the theory into its modern mathematical form. Their predictions inspired new experiments. At the Physics Institute of Frankfurt University headed by Max Born, physicists Otto Stern and Walter Gerlach made important contributions using a new experimental method. This will be commemorated by a “historic site" plaque that was unveiled Tuesday in a ceremony in the historic auditorium of the Jügelhaus, formerly the main Goethe University building on Bockenheim Campus. Once the Historical Monument Department has approved, the plaque will be mounted onto the former physics building at Robert-Mayer-Straße 2.
“Everyone is familiar with Goethe, but Nobel Prize winner Otto Stern is still largely unknown,“ comments University President Birgitta Wolff. “The university named its new auditorium complex on Riedberg Campus after Otto Stern a few years ago. I'm delighted that a Historic Site Plaque now marks the location where Otto Stern succeeded with his pioneering experiments."
The “historic site" plaque is awarded by the European Physical Society to commemorate important discoveries in physics in laboratories, institutes or cities throughout Europe. The former Institute of Theoretical Physics building in Frankfurt is the fourth location in Germany to be distinguished with this plaque.
“The year 2019 presents a two-fold opportunity to remember the pioneer of quantum physics and Nobel Laureate Otto Stern," explains physics professor Horst Schmidt-Böcking, who authored a biography of Otto Stern together with the historian Karin Reich. In 1919, Otto Stern developed the molecular beam method, for which he received the Nobel Prize for Physics in 1943. In the iconic Stern-Gerlach experiment, completed in February 1922, the reality of space quantization of angular momentum had been demonstrated. The momentum resolution achieved corresponded to an energy resolution of a micro electron volt. In 1922, together with Walther Gerlach in the iconic Stern-Gerlach experiment, the reality of space quantization of angular momentum was demonstrated, also proving the angular momentum quantization in atoms for the first time. “At the same time, we commemorate the 50th anniversary of Otto Stern's death, who was forced to emigrate in 1933 because of his Jewish background," remarks Schmidt-Böcking.
Otto Stern first settled in Pittsburgh and then Berkeley in 1945. In contrast to many other emigrants, he took every opportunity after the Second World War to meet with friends and colleagues at conferences in Europe. Horst Schmidt-Böcking has been in contact with Otto Stern's descendants in the United States in recent years and invited them to visit their uncle's old domain. Stern himself had no children.
“The Historic Site Plaque also commemorates other important discoveries made at the Physics Institute," says Petra Rudolf, President of the European Physical Society. “In 1920 Max Born and Elisabeth Bormann first measured the free path of atoms in gases and the size of molecules. In 1921, the theoretician Alfred Landé postulated the coupling of angular momentum for the first time as the basis of intra-atomic electron dynamics."
An international conference commemorating Otto Stern is taking place this week, as Wilhelm and Else Heraeus Seminar entitled “Otto Stern's Molecular Beam Research and its Impact on Science". Speakers include people who knew Stern such as his nephew Allen Templeton, scientific historians, and researchers whose experimental methods are based on the molecular beam method developed by Stern, such as magnetic resonance imaging, lasers and masers. The conference goes until 5th September.
Today, the historical building is home to the Physical Association of Frankfurt. Founded in 1824, it is the oldest one in Germany and was already in existence in 1914 when the university opened.
Further information: Dr. Horst Schmidt-Böcking, Institut für Kernphysik, Fachbereich Physik, Riedberg Campus, Tel.: +49 69 798 47002, firstname.lastname@example.org
Theoretical physicists at Goethe University discovered that cultural processes are accelerating
FRANKFURT. Cultural processes are increasingly short-lived, showing in addition a growing tendency toward self-organisation. As a result, success is now governed by a universal law. This was discovered by the physicists Professor Claudius Gros and Lukas Schneider from Goethe University. Their object of research: 50 years of music charts.
Since the 1960s, music charts have been compiled using the same criteria - sales profits. Charts therefore provide sets of comparable data spanning many decades, a circumstance that makes them particularly well-suited for the investigation of the long-term development of cultural time scales. This approach is also relevant beyond the cultural domain, in particular with regard to the pace of political opinion formation, which affects the dynamical stability of liberal democracies.
In a new article published today in Royal Society Open Science, Lukas Schneider and Professor Claudius Gros from the Institute for Theoretical Physics at Goethe University demonstrate that the statistical characteristics, the composition, and the dynamics of the US, UK, Dutch and German pop album charts have changed significantly since the beginning of the 1990s. On the one hand, the diversity of the charts has doubled, or even tripled: Now there are significantly more albums making it to the top 100 or top 40 in a year. On the other hand, we now see that an album either starts off immediately as number one – or never reaches the top. In contrast, from the 1960s to the 1980s, successful albums needed four to six weeks to work their way from their starting position to the top slot.
The nature of an album's “lifetime" - the number of weeks an album has been listed – was found to have changed profoundly. Before the 1990s, the statistics of album lifetimes were governed by a Gauss distribution with a logarithmic argument (log normal). Today, the distribution of album lifetimes is characterised in contrast by a power law. The distribution of lifetimes is therefore universal, i.e., independent of the specifics of the process, a key characteristic of the final state of a self-organising process. To explain this development, the authors propose an information-theoretical approach to human activities. The assumption of Schneider and Gros is that humans strive continuously to optimise the information content of their experience and perceptions. Mathematically, information is captured by the Shannon entropy. According to Schneider and Gros, one needs to consider furthermore the Weber-Fechner law, which states that time and other variables are represented and stored in the brain not in a one-to-one ratio, but in a greatly compressed way (on a logarithmic scale). In this view, optimization of the information content of compressed experiences explains the observed chart statistics.
Overall, the study by Schneider and Gros shows that chart dynamics has accelerated, proceeding today substantially faster than several decades ago. The authors conjecture that a similar acceleration could also be at work for the underlying socio-cultural processes, such as social and political opinion formation. As an earlier work by Gros shows, this could threaten the dynamical stability of modern democracies, as the functioning of democracies is based on reliable temporal ties between electorate and political institutions. These temporal ties are threatened when the time scale of political opinion formation and that of the delayed decision processes drift increasingly apart. (Claudius Gros, Entrenched time delays versus accelerating opinion dynamics: Are advanced democracies inherently unstable? European Physical Journal B 90, 223 (2017). https://epjb.epj.org/articles/epjb/abs/2017/11/b170341/b170341.html )
Publication: Lukas Schneider, Claudius Gros, Five decades of US, UK, German and Dutch music charts show that cultural processes are accelerating, Royal Society Open Science (2019) https://royalsocietypublishing.org/doi/10.1098/rsos.190944
Further information: Professor Claudius Gros, Institute for Theoretical Physics, Riedberg Campus, telephone: +41 69 798 47818, E-mail email@example.com.
Frankfurt researchers have explained the mechanism of regulator SidJ in detail / Accelerated publication in Nature
FRANKFURT. In order to control cellular processes and thwart the immune system, the bacterium Legionella pneumophilia, the cause of the notorious Legionnaires' disease, releases hundreds of enzymes. Biochemists at Goethe University have now elucidated important details in the interaction of bacterial effectors. They discovered how the regulatory enzyme SidJ keeps other dangerous virulence factors in check.
The incidence of Legionnaires' disease has increased in the past two decades. The natural habitat of Legionella is freshwater biotopes, where they mainly reproduce in amoebae. In addition, Legionella can also colonize water tanks or pipes and spread, for example, via poorly maintained air-conditioning systems. Contaminated aerosols are released into the air and trigger the infection. The pathogens cause, among others, pneumonia, which is often fatal in elderly patients or individuals with a weak immune system.
What makes Legionella so dangerous is its ability to multiply in phagocytes of the immune system by secreting virulence factors. Some of these effectors – the enzymes of what is known as the SidE family – are so toxic that without tight control they would instantly kill their host cells. However, since Legionella needs the host cells in order to multiply, it has developed a sophisticated mechanism for the precise metering of SidE enzyme activity. Details of this process are now reported by scientists at Goethe University and from Grenoble in the journal Nature.
They have shown that the regulator SidJ also released by Legionella works as an antidote to SidE enzymes, thus ensuring accurate control of SidE activity. The SidJ regulator is a glutamylase, i.e. it has a rare enzyme activity that allows amino acid glutamates to be linked together to form chains. In this case, SidJ attacks the central glutamate of SidE enzymes and inhibits their activity. So far, little is known about glutamylases – so the scientists were all the more surprised when they discovered that it is precisely this type of enzyme which is important for the coordinated interaction of the virulence factors of Legionella.
“This is a typical example of how completely unpredictable results drive research. Such discoveries are what make science such a fascinating and exciting profession," says Professor Ivan Dikic from the Institute of Biochemistry II and the Buchmann Institute for Molecular Life Sciences at Goethe University. “We can only gain a molecular understanding of the complex world of bacterial infections by working in interdisciplinary teams and combining methods from modern biochemistry and proteomics with cell and structural biology techniques."
The researchers also revealed how SidJ is activated in host cells: It requires the calcium-binding protein calmodulin found in mammalian cells. Cryo-electron microscopy played an important role in explaining the structure of the calmodulin-SidJ complex. “Glutamylation as a protein modification is understudied. Our finding that Legionella pneumophilia uses exactly this mechanism to sustain the infection certainly argues for more research in this field. For example, the extent to which Legionella utilizes this modification to regulate other cellular processes is completely unclear," explains Dr. Sagar Bhogaraju, who led the microscopic examinations at the European Molecular Biology Laboratory (EMBL) in Grenoble.
This so far unknown mechanism opens up new possibilities for research to inhibit the spread of Legionella in the host organism. “We're currently working on eliminating SidJ selectively by developing inhibitors for the glutamylase domain. In addition to the use of antibiotics, they could prevent the spread of Legionella pneumophilia in phagocytes," explains Dikic.
Publication: Sagar Bhogaraju, Florian Bonn, Rukmini Mukherjee, Michael Adams, Moritz M. Pfleiderer, Wojciech P. Galej, Vigor Matkovic, Sissy Kalayil, Donghyuk Shin, Ivan Dikic: Inhibition of SidE ubiquitin ligases through SidJ/Calmodulin catalyzed glutamylation, in Nature 22. Juli 2019 DOI: 10.1038/s41586-019-1440-8 https://www.nature.com/articles/s41586-019-1440-8
Further information: Professor Ivan Dikic, Institute of Biochemistry II, Niederrad Campus, and Buchmann Institute for Molecular Life Sciences, Riedberg Campus, Tel.: +49(0)69-6301-5964, Email: firstname.lastname@example.org.
New insights into ribosome recycling with enzyme ABCE1
Ribosomes are molecular machines that produce proteins in cells. Having finished the job, the ribosomes need regenerating. This process is important for the quality of the proteins produced and thus for the whole cell homeostasis as well as for developmental and biological processes. Biochemists from Goethe University Frankfurt together with biophysicists at LMU Munich have now watched one of the most important enzymes for ribosome recycling at work – ABCE1 – and shown that it is unexpectedly versatile in terms of structure.
Ribosomes decode the genetic information from the messenger RNAs and translate it into proteins. Once they have produced a protein, but also if defective proteins have come to a halt in the ribosome, the ribosomes have to be “recycled" so that they are in good working order for a new round of synthesis. In all organisms (except bacteria), the enzyme ABCE1 coordinates this process, in which the ribosome is split into its two subunits. Biochemist Robert Tampé and LMU biophysicist Thorben Cordes, in collaboration with researchers at the University of Groningen (Netherlands), have shown that ABCE1 adopts three structural conformations to boost recycling. Their results are presented in the current issue of the journal Cell Report.
The ABCE1 enzyme can split ATP, the energy currency of cells, and use the energy released to separate the two ribosomal subunits. “Recent structural and functional data have shown that a conformational change of the enzyme, that is, a change in its spatial structure, is essential within this process for the diverse functions of ABCE1," says Cordes. Using an integrated test approach – among others with the help of what is known as the single-molecule FRET method – his team has now observed at first hand the structural variability of ABCE1 at the level of single molecules.
In the course of this work, the researchers established that the two ATP binding sites of ABCE1 can adopt three conformations – open, intermediate and closed – which are in a state of dynamic equilibrium. Interaction of ABCE1 with both the ribosome and the ATP influences the structural dynamics of the two ATP binding sites. This results in a complex network of different states, in which ribosome and ATP shift the equilibrium in the direction of the closed conformation.
“We assume that the conformations perform functionally different roles in the dissociation of the ribosome as well as for the many other diverse functions of ABCE1," says Cordes. “Ribosome recycling is governed by an extraordinarily complex and conserved machinery, which has medical significance as yet unimagined," adds Robert Tampé.
Cell Reports 2019
Publication: Giorgos Gouridis, Bianca Hetzert, Kristin Kiosze-Becker, Marijn de Boer, Holger Heinemann, Elina Nürenberg-Goloub, Thorben Cordes, Robert Tampé: ACBE1 controls ribosome recycling by an asymmetric dynamic conformational equilibrium, in: Cell Reports 2019 DOI: 10.1016/j.celrep.2019.06.052 https://doi.org/10.1016/j.celrep.2019.06.052
Further information: Professor Robert Tampé, Institute of Biochemistry, Faculty of Biochemistry, Chemistry and Pharmacy, Riedberg Campus, Tel.: +49(0)69-798-29475 , Email: email@example.com, www.biochem.uni-frankfurt.de
Image material can be downloaded under: http://www.uni-frankfurt.de/80584137
Caption: Three states of nucleotide binding sites can be seen in the histogram: open, intermediate and closed. Image: T. Cordes, LMU Munich
Study shows: MRI on par with cardiac catheterization
FRANKFURT. The non-invasive measurement of blood flow to the heart using magnetic resonance imaging (MRI) is on par with cardiac catheterization. This was the result of an international study published in the current issue of the New England Journal of Medicine and headed by researchers from Goethe University.
For patients with chest pain and presumably stable coronary heart disease (CHD), therapy depends primarily on how constricted the arteries that support the heart are (coronary arteries). This is often determined using an invasive procedure called cardiac catheterization. If necessary, the pressure in the coronary arteries is also measured. The combination of these methods is the currently the recognized standard for making therapy decisions. Cardiovascular magnetic resonance imaging (MRI) is an alternative for directly measuring the blood flow in the myocardium.
In contrast to cardiac catheterization, MRI is non-invasive, works without ionising radiation, can be done in 40 minutes and delivers direct measurements of the blood flow to the heart. The team headed by Professor Eike Nagel, Director of the Institute for Experimental and Translational Cardio Vascular Imaging at Goethe University was able to demonstrate that MRI measurements are as safe to guide decision-making as the currently used invasive procedure. Within the international MR-INFORM study, they examined 918 patients with an indication for cardiac catheterization to see if decision-making by an MRI scan led to the same results as the current invasive method.
Patients were randomly assigned to two groups. One group received the standard diagnostic investigation with cardiac catheterization and pressure measurement of the coronary arteries. The other had the 40 minute MRI scan of the heart to decide whether to send the patient on for invasive angiography.
In each study arm, constricted coronary vessels were dilated when indicated by the examination. In the following year, the physicians documented how many patients died, suffered a heart attack or required a repeated vascular dilation. In addition, they recorded whether the heart symptoms continued.
The result: in the group of patients examined by MRI, less than half required a diagnostic cardiac catheterization and fewer patients received a vascular dilation (36% vs 45 %). This means that with a fast and non-invasive MRI examination as the first test, both diagnostic and therapeutic cardiac catheterizations can be reduced. Importantly, the two groups did not differ in terms of continuing symptoms, the development of new symptoms, complications, or deaths.
“This means that patients with stable chest pains who previously would have received cardiac catheterization can alternatively be examined with MRI," concludes Professor Eike Nagel. “The results for the patients are just as good, but an examination by MRI has many advantages: the procedure takes about 40 minutes, patients merely receive a small cannula in their arm and are not subject to radiation." The physician hopes that the less invasive method will now be used as a method of first choice, reducing the need for cardiac catheterizations.
In contrast to Great Britain, where an MRI scan of the heart is paid for by the National Health Service (NHS), reimbursement is often difficult in Germany and usually has to be negotiated individually. In this regard, Nagel also hopes that the study will contribute to the acceptance of the non-invasive procedure and improve its availability.
Financial support was provided primarily by the British National Institute of Health Research (NIHR) via the Biomedical Research Centre (BRC) at Guy's & St. Thomas' Hospital, the German Centre for Cardiovascular Research (DZHK) and the company Bayer AG Deutschland.
A picture can be downloaded here: http://www.uni-frankfurt.de/78920068
Caption: Measuring blood flow in the myocardium with magnet resonance imaging (top). The dark area in the myocardium (arrows) shows a pronounced reduction of blood flow. The cardiac catheterization of the same patient (bottom) shows a clear constriction of the artery. Credit: Eike Nagel, Goethe University
Publication: Magnetic Resonance Perfusion or Fractional Flow Reserve in Coronary Disease Eike Nagel, et al., N Engl J Med 2019;380:2418-28. DOI: 10.1056/NEJMoa1716734
Further information: Professor Eike Nagel, Institute for Experimental and Translational Cardiovascular Imaging, Faculty of Medicine, Niederrad Campus, Tel.: +49 151 4197 4195, firstname.lastname@example.org