Xiaoping Bao, a Purdue University assistant professor from the Davidson School of Chemical Engineering, said CAR-neutrophils, or chimeric antigen receptor neutrophils, and engraftable HSCs, or hematopoietic stem cells, are effective types of therapies for blood diseases and cancer. Neutrophils are the most abundant white cell blood type and effectively cross physiological barriers to infiltrate solid tumors. HSCs are specific progenitor cells that will replenish all blood lineages, including neutrophils, throughout life.

“These cells are not readily available for broad clinical or research use because of the difficulty to expand ex vivo to a sufficient number required for infusion after isolation from donors,” Bao said. “Primary neutrophils especially are resistant to genetic modification and have a short half-life.”

Bao has developed a patent-pending method to mass-produce CAR-neutrophils from human pluripotent stem cells (hPSCs), that is, cells that self-renew and are able to become any type of human cell. The chimeric antigen receptor constructs were engineered to express on the surface of the hPSCs, which were directed into functional CAR-neutrophils through a novel, chemically defined protocol.

The method was created in collaboration with Qing Deng at Purdue’s Department of Biological Sciences, Hal E. Broxmeyer, now deceased, at Indiana University School of Medicine, and Xiaojun Lian at the Pennsylvania State University.

“We developed a robust protocol for massive production of de novo neutrophils from human pluripotent stem cells,” Bao said. “These hPSC-derived neutrophils displayed superior and specific antitumor activities against glioblastoma after engineering with chimeric antigen receptors.”

Bao disclosed the innovation to the Purdue Research Foundation Office of Technology Commercialization, which has applied for an international patent under the Patent Cooperation Treaty system of the World Intellectual Property Organization. The innovation has been optioned to an Indiana-headquartered life sciences company.

“We will also work with Dr. Timothy Bentley, professor of neurology and neurosurgery,and his team at the Purdue College of Veterinary Medicine to run clinical trials in pet dogs with spontaneous glioma,” Bao said.

This research project was partially supported by the Davidson School of Chemical Engineering and College of Engineering Startup Funds, Purdue Center for Cancer Research, Showalter Research Trust and federal grants from the National Science Foundation and National Institute of General Medical Sciences.

Story Source:

Materials provided by Purdue University. Original written by Steve Martin. Note: Content may be edited for style and length.

With that in mind, a team of University of Arizona students and faculty completed a comprehensive study to track and characterize the brightness of satellites, using a ground-based sensor they developed to measure satellites’ brightness, speed and paths through the sky. Their work could be helpful for astronomers, who, if notified of incoming bright satellites, could close the shutters of their telescope-mounted cameras to prevent light trails from tainting their long-exposure astronomical images.

The research team was led by professor of planetary sciences Vishnu Reddy, who also co-leads — with professor of systems and industrial engineering Roberto Furfaro — the university’s Space Domain Awareness lab, which tracks and characterizes all kinds of objects orbiting Earth and the moon.

Grace Halferty, a senior graduating this summer with a bachelor’s degree in aerospace and mechanical engineering, is the lead author of the study, which is published in Monthly Notices of the Royal Astronomical Society. The study details how the team created a satellite tracking device to measure the brightness and position of SpaceX Starlink satellites and compared those observations to government satellite tracking data from the Space Track Catalog database.

“Until now, most photometric — or brightness — observations that were available were done by naked eye,” Halferty said. “This is one of the first comprehensive photometric studies out there to go through peer review. The satellites are challenging to track with traditional astronomical telescopes, because they are so bright and fast-moving, so we built what’s basically a small sensor with a camera lens ourselves because there was nothing off the shelf available.”

The team made 353 measurements of 61 satellites over two years and found that the position of Starlink satellites as recorded in the government’s Space Track Catalog only differed by an average of 0.3 arc seconds from the UArizona calculations. An arc second on the sky is about the size of a dime held 2.5 miles away. The tiny difference is probably due to natural lag times in the government data, Reddy said. Because that data is based on estimated orbits calculated days earlier, rather than on real-time observations, positioning errors can build up.

“This suggests that there is hope that astronomers can use these data to close the shutter of their telescopes in time amid the growing chaos in the skies above,” Reddy said.

A stellar traffic jam

Starlink is a large network of satellites, also called a mega constellation, operated by SpaceX with the goal of providing global internet coverage. SpaceX started launching Starlink satellites in 2019. Today, more than 2,700 Starlink satellites have launched — a fraction of the intended total of 42,000 satellites.

Other examples of satellite constellations include 31 GPS satellites and 75 iridium satellites for communication. Other entities have plans to launch more satellites into low and medium Earth orbit in the next few years. Amazon, for example, plans to launch 3,000 satellites, and the Chinese government plans to launch 13,000. These satellites will orbit no higher than 22,000 miles above Earth.

The problem with satellites is that they require power harvested from solar panels, which can reflect sunlight at ground-based telescopes and, in turn, impact astronomical observations from telescopes around the world. About 30% of all telescope images will be impacted by at least one satellite trail once the Starlink constellation is complete, said research team member Tanner Campbell, a graduate research assistant in the Department of Aerospace and Mechanical Engineering.

“As other constellations are added, the problem will only get worse for ground-based astronomical surveys,” he said.

These satellites are even more reflective right after launch, while they are still relatively low and tightly clustered before they spread throughout their orbit over time. They are often as bright as Saturn or Jupiter, two of the brightest objects in the night sky. As they maneuver into higher orbits, they become slightly fainter.

A moving target

SpaceX has deployed a few different methods to darken its Starlink satellites. For example, VisorSat satellites rely on a shade to block additional sunlight, making them 1.6 times fainter. DarkSat satellites, on the other hand, rely on an anti-reflective coating that makes them 4.8 times fainter. However, DarkSats got too hot, so SpaceX moved away from that specific method. Since August 2021, all Starlink satellites are VisorSats.

“While these modifications are steps in the right direction, they also don’t dim the satellites enough for astronomical surveys,” said research team member Adam Battle, a graduate student studying planetary science.

In July, SpaceX announced new strategies. One involves mirrors that reflect sunlight away from Earth and another involves using darker building materials. Reddy’s team plans to study how effective these methods are at reducing sunlight reflection back to Earth.

While knowing exactly where satellites are is helpful to astronomers, the act of shutting the cameras adds overhead costs for telescope operations. Surveys become less efficient when astronomers have to close the shutter or throw away contaminated images. For example, a survey that would take five years to complete could take 10% to 20% more time if survey efficiency is down. Costs will continue to increase as more satellites are launched, Reddy said.

The team plans to build upon its success by studying the brightness of the latest generation of Starlink satellites in four different colored filters — the same ones used in astronomical surveys of the sky to tease out different information from stars, planets and more. To achieve this, the team has worked with Tucson-based small business Starizona to build a sensor that can take pictures of satellites in four colors simultaneously.

“Working with local small businesses is a win for us as it provides our students an opportunity to rapidly prototype and bring a new system online,” Reddy said.

“The results are highly relevant for combating fungal infections in clinical practice, veterinary medicine and agriculture,” says Professor Ulrich Kück, Senior Professor in General and Molecular Botany at RUB. He cooperated for the project with the Bochum researcher Dr. Tim Dahlmann and the team headed by Professor Dr. Joe Heitman, who is currently based at Duke University in North Carolina and has been a visiting professor at RUB on several occasions.

Number of fungal infections on the rise

“In the western hemisphere, the number of people with a lowered immune defence is increasing, because life expectancies are rising rapidly and treatment with immunosuppressants after organ transplants is becoming more common,” explains Ulrich Kück. “This is associated with an increase in fungal infections.” Cryptococcus neoformans is one of the most significant human pathogenic fungi responsible for so-called cryptococcosis. It triggers acute infections in immunocompromised patients; and the mortality rate may be as high as 70 per cent. This is because fungal strains that are resistant to the drugs often evolve in hospitals, which makes treatment more difficult. So far, it was unclear which cellular and genetic mechanisms lead to this resistance.

So-called transposons, however, were known to play a role in the resistances. Transposons are jumping genes, i.e. DNA segments that can change their position in the genome and thus affect the function of genes. If a transposon jumps into a gene that’s critical for susceptibility to a drug, it’s possible for resistance to emerge. The mobility of the transposons is controlled by regulatory RNAs, so-called small interfering RNA, or siRNA for short.

RNA mechanism causes resistance

In their current study, the researchers discovered gene mutations in resistant isolates that led to siRNA control being switched off. By introducing an intact copy of the gene, it was possible to restore siRNA control; as a result, the researchers were able to prevent the transposons from jumping and shed light on the cause of resistance. Due to their small size, the gene segments that code for siRNAs are not easy to find in the genome. Tim Dahlmann managed to locate them with special bioinformatic analyses. By identifying the resistance mechanisms, it will be possible to use them for the treatment of mycoses in humans in the future.

Story Source:

Materials provided by Ruhr-University Bochum. Original written by Julia Weiler. Note: Content may be edited for style and length.

A bacterial syringe delivers a deadly enzyme

The mechanism of action of Tc toxins has only recently been uncovered to a greater extent by the work of Stefan Raunser’s team in structural biology at the MPI Dortmund. “Unraveling the structure of the Tc toxin subunits and their assembly by cryo electron microscopy (cryo-EM) enabled us to understand the key steps of toxin activation and membrane penetration,” says Raunser. The scientists showed that the subunits of the Tc toxin complex work together like a syringe: once the subunits are assembled, structural changes in the complex trigger the opening of a cocoon which contains a toxic enzyme, which is then secreted in a unique injection mechanism via a channel into the host cell. There, it unfolds its deadly effect by disturbing the regulation of the cell’s cytoskeleton, which consists of a network of polymerized actin (F-actin) filaments involved in many essential cellular processes.

Setting up the opponent by reducing the striking distance

“For a long time, we struggled with obtaining a complete picture of the intoxication process, since we lacked the structural data of the secreted enzymes, one of which is TccC3,” reflects Raunser. Until recently, it was only known that TccC3 transfers an ADP-ribose group to actin promoting its aberrant polymerization, which leads to actin filament clumping. “TccC3 is what we call a “difficult” system for structural investigations due to its size and high flexibility,” says Hartmut Oschkinat. “Only by applying solution NMR, could we overcome this challenge and visualize the protein’s 3D structure for the first time.” By fusing two further cryo-EM snapshots of TccC3 bound to F-actin and of the modified F-actin alone, the scientists have uncovered the enzyme’s unique mechanism of action. “TccC3 acts like a boxer who sets up his opponent to make him vulnerable to the attack” says Stefan Raunser. In the first step, the enzyme binds to a region between two consecutive actin subunits of F-actin. TccC3 then opens a gate, which brings the molecule NAD+ that contains the ADP-ribose group within striking distance to a reactive site on actin. Once the bulky ADP-ribose group is transferred to F-actin, it is no longer accessible for its depolymerizing factors, whereby F-actin can no longer be broken down and thus clumps.

In addition to this discovery, the scientists’ findings have helped formulate an explanation for the strikingly high efficiency of the enzyme. When the enzyme detaches from F-actin, its gate mechanism prevents a futile rebinding to the already modified actin as preparation for the next attack. “It is amazing how all these mechanisms evolved to increase the toxins potency to the max. And nature did quite a good job since botulinum toxins, ricin and other biotoxins are still considered the most toxic substances known,” Raunser concludes.

Story Source:

Materials provided by Max Planck Institute of Molecular Physiology. Note: Content may be edited for style and length.

Cured and processed meats, such as salami and bacon, are often treated with nitrite or nitrate salts to keep them looking and tasting fresh. Though nitrate is relatively stable, it can be converted to the more reactive nitrite ion in the body. When in the acidic environment of the stomach or under the high heat of a frying pan, nitrite can undergo a reaction to form nitrosamines, which have been linked to the development of various cancers. Some methods to determine nitrite levels in foods already exist, but they are not very consumer-friendly and often require expensive and laborious techniques and instruments. To help consumers make more informed decisions, Saúl Vallejos, José M. García and colleagues wanted to develop an easy-to-use nitrite quantification system.

To accomplish this, the researchers developed a film they called “POLYSEN,” which stands for “polymeric sensor,” made of four monomers and hydrochloric acid. Disks punched from the material were placed on meat samples for 15 minutes, allowing the monomer units and acid in the film to react with nitrite in a four-step azo coupling reaction. The disks were then removed and dipped in a sodium hydroxide solution for one minute to develop the color. When nitrite was present, the film’s yellowish hue deepened with higher nitrite levels in the food. To quantitate the color change, the researchers created a smartphone app that self-calibrates when a chart of reference disks is photographed in the same image as the sample disks.

The team tested the film on meats they prepared and treated with nitrite, in addition to store-bought meats, and found that the POLYSEN-based method produced results similar to those obtained with a traditional and more complex nitrite detection method. In addition, POLYSEN complied with a European regulation for migration of substances from the film to the food. The researchers say the new approach could be a user-friendly and inexpensive way for consumers to determine nitrite levels in foods.

The authors acknowledge funding from La Caixa Foundation and the Spanish Agencia Estatal de Investigación. They also acknowledge the support and collaboration of the company Inforapps.

Story Source:

Materials provided by American Chemical Society. Note: Content may be edited for style and length.