Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), in cooperation with colleagues at the University of Zurich and the Ruhr-Universität Bochum, have for the first time successfully tested a new tumour diagnosis method under near-real conditions. The new method first sends out an antibody as a ‘spy’ to detect the diseased cells and then binds to them. This antibody in turn attracts a subsequently administered radioactively labelled probe. The scientists could then clearly visualize the tumour by utilizing a tomographic method. This procedure could improve cancer treatment in the future by using internal radiation.

The human immune system forms antibodies that protect the body from pathogens. Antibodies can also, however, be produced in a laboratory to precisely bind to tumour cells. They are used in cancer research to detect and fight malignant tumours. For example, antibodies can serve as transport vehicles for radionuclides, with which the affected regions can be visualized or can even be damaged. Until recently, a stumbling block has been their large molecular mass. “This causes them to circulate in the body for too long before they reach the diseased cells,” explains Dr Holger Stephan from the Institute of Radiopharmaceutical Cancer Research at HZDR. ‘This is a disadvantage because organs that are not affected by the disease are exposed to radiation. It also makes the exact localization of the tumour in the body more difficult because the resulting images are less sharp.”

Together with colleagues at the University of Zurich and the Ruhr-Universität Bochum, the researchers from Dresden therefore chose an alternative strategy. “By using what is known as ‘pre-targeting’, the antibodies’ task is divided into two steps,” Dr Kristof Zarschler, a member of Stephan’s team, explains. “In a figurative sense, we first send spies out in advance, over a longer period of time, to scout out the enemy – the tumour cells. The ‘spies’ then share their position with their troops, which we subsequently send out so that they will directly reach their target with the radioactive material.” The researchers fall back on the cetuximab antibody as the scout, which binds selectively to the epidermal growth factor receptor (EGFR). In various types of tumours, there is an increase in this molecule’s formation or it might be found in a mutated form, which then leads the cells to grow and multiply uncontrolled.

The Dresden researchers combined the antibody with a peptide nucleic acid (PNA) derivative which Prof Gilles Gasser and Prof Nils Metzler-Nolte developed together with their respective working groups in Switzerland and Germany. “It is a very stable synthetic variant of DNA,’ says Holger Stephan. “Similar to a single strand of DNA, it consists of a certain sequence of the four organic bases. Complementary PNA with matching sequence binds to it in a highly precise and stable manner.” During their experiments, the scientists first injected the PNA-EGFR antibody into tumour-bearing mice and gave this “spy” time to accumulate at the tumour site. They then administered the PNA counterpart, labelled with the radioactive substance technetium-99m. “Images we took using single photon emission computed tomography show that both the antibody and its counterpart located each other quickly,” says Zarschler, pleased with the results.

The tumour could thus be clearly visualized within a short period of time. “Furthermore, the radioactively labelled probes had already disappeared from the bloodstream after sixty minutes,” explains Holger Stephan. “This minimizes radioactive exposure risk of healthy body tissue. By pre-targeting, we can overcome limitations of conventional, radioactively marked antibodies.” According to the researchers, it will, however, take some time before the combination of PNA antibodies and their matching PNA counterparts can be used in diagnosing tumours in humans.

“Our results however show that the PNAs we tested are suitable candidates for further preclinical studies,” Stephan sums up. They could provide new possibilities not only for visualizing diseased cells but also for fighting them. “If the method is proven to work, it could also be used to transport therapeutically effective radioactive substances to the tumour in order to irradiate it from within and ultimately damage it.” Helmholtz-Zentrum Dresden-Rossendorf

Researchers at The University of Texas Health Science Center at Houston (UTHealth) are helping to make precision medicine a reality by sequencing entire exomes of people to assess chronic disease risk and drug efficacy.

For years, scientists have been using a method called “knockout mice,” which allows them to study gene functions by inactivating a gene in mice and then observing how it affects the mice. Now, UTHealth researchers are using new methods to study naturally occurring “knockout humans.”

Rather than genetically engineer human gene mutations in the lab, UTHealth researchers scanned 8,554 exomes, the protein-encoding portion of the genome, of African Americans and European Americans in the United States for naturally occurring mutations that inactivate a certain gene. A typical human exome has dozens of these loss-of-function gene variants.

“Years ago, we found a mutation that knocks out a gene that lowers your cholesterol. That turned into drugs that can help with cholesterol. That was with one gene. We are now sequencing lots of people and looking at where people are losing function from every gene in their body,” said Eric Boerwinkle, Ph.D., senior author, professor and chair of the Human Genetics Center and the Department of Epidemiology, Human Genetics and Environmental Sciences at UTHealth School of Public Health.

The study participants were part of Atherosclerosis Risk in Communities (ARIC), a study conducted by the National Heart, Lung and Blood Institute (NHLBI). The group was measured for 20 phenotypes related to chronic diseases, such as serum magnesium levels, triglyceride levels, blood pressure and cholesterol.

By observing how certain mutations affect health, researchers were able to identify eight new relationships between genes and diseases and confirm the already established relationship between gene variant PCSK9 and lower blood cholesterol and lower heart disease risk.

A heterozygous form of gene TXNDC5 was found to be related to Type 1 Diabetes progression and elevated fasting glucose levels. A recessive form of C1QTNF8 was related to elevated serum magnesium levels and participants who had a mutation of SEPT10 had significantly reduced lung function.

“Loss-of-function variation in certain genes, such as TXNDC5, may predispose individuals to develop disease. More research is needed to determine the exact mechanisms of these newly discovered relationships,” said Boerwinkle, who is also the Kozmetsky Family Chair in Human Genetics at UTHealth. University of Texas at Houston Health Science Center

Unreliable oestrogen measurements have had a negative impact on the treatment of and research into many hormone-related cancers and chronic conditions. To improve patient care, a panel of medical experts has called for accurate, standardized oestrogen testing methods in a statement published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM).
The panel’s recommendations are the first to address how improved testing methods can affect clinical care, and were developed based on discussions at an oestrogen measurement workshop hosted by the Endocrine Society, AACC and the Partnership for Accurate Testing of Hormones (PATH).

Oestrogen is primarily produced in the ovaries and is also produced in small amounts by the adrenal glands, which is why men as well as women have oestrogen in their bodies. It is critical for fertility in women, and also plays a role in many health conditions, from precocious puberty to cancers of the breast, ovary, prostate and liver. Accurate blood tests for oestrogen are necessary to diagnose patients with these conditions and ensure they receive appropriate, effective treatment. Many medical studies also rely on oestrogen tests, such as research assessing the connection between oestrogen levels and the risk of breast or prostate cancer.

“Accurate data on patients’ oestrogen levels are needed to ensure appropriate and effective patient care, reduce the need for retesting, and enable clinicians to implement the latest research in patient care,” said one of the authors and co-chair of the PATH Steering Committee, Hubert Vesper, PhD. “Research studies, however, found high inaccuracies among different oestrogen tests, especially when the test is measuring low oestrogen levels in postmenopausal women, men and children.”

The expert panel called for improving the accuracy of measurements through standardization, and recommended clinicians, researchers and public health officials support standardization programs like CDC’s and other efforts to ensure oestrogen measurement is accurate and consistent.

The panel also advised clinicians and researchers to consider the purpose of the test when selecting an oestrogen measurement method. Clinicians and researchers currently use several methods to measure oestrogen, including mass spectrometry and immunoassays. The experts agreed both methods are valid, but that one may be more effective than the other depending on the situation. For instance, mass spectrometry—the more expensive, but also more sensitive testing method—may be appropriate in people who tend to have low oestrogen levels, including postmenopausal women and children beginning puberty.

Additionally, the experts recommended that medical journals require authors to fully explain the oestrogen measurement testing methods used in studies. Ensuring researchers explain the processes they used will help the field move toward standardized methods. The Endocrine Society

Infectious diseases such as hepatitis C and some of the world’s deadliest superbugs — C. difficile and MRSA among them — could soon be detected much earlier by a unique diagnostic test, designed to easily and quickly identify dangerous pathogens.

Researchers at McMaster University have developed a new way to detect the smallest traces of metabolites, proteins or fragments of DNA. In essence, the new method can pick up any compound that might signal the presence of infectious disease, be it respiratory or gastrointestinal.

‘The method we have developed allows us to detect targets at levels that are unprecedented,’ says John Brennan, director of McMaster’s Biointerfaces Institute, where the work was done.

‘The test has the best sensitivity ever reported for a detection system of this kind — it is as much as 10,000 times more sensitive than other detection systems,’ he says.

Using sophisticated techniques, researchers developed a molecular device made of DNA that can be switched ‘on’ by a specific molecule of their choice — such as a certain type of disease indicator or DNA molecule representing a genome of a virus — an action that leads to a massive, amplified signal which can be easily spotted.

Another important advantage of the new test, say researchers, is that the method does not require complicated equipment so tests can be run at room temperature under ordinary conditions.

‘This will be the foundation for us to create future diagnostic tests,’ explains Yingfu Li, a professor in the Departments of Biochemistry and Biomedical Sciences, Chemistry and Chemical Biology.

‘This invention will allow us to detect anything we might be interested in, bacterial contamination or perhaps a protein molecule that is a cancer marker. Our method can sensitively detect all of them, and it can do so in a relatively short period of time.’

Researchers are currently working to move the test onto a paper surface to create a portable point-of-care test, which would completely eliminate the need for lab instruments, allowing users — family physicians, for example — to run the test.

The Biointerfaces Institute has developed a series of paper-based screening technologies which enable users to generate clear, simple answers that appear on test paper indicating the presence of infection or contamination in people, food or the environment. McMaster University

Genetic studies in humans, zebrafish and mice have revealed how two different types of genetic variations team up to cause a rare condition called Hirschsprung’s disease. The findings add to an increasingly clear picture of how flaws in early nerve development lead to poor colon function, which must often be surgically corrected. The study also provides a window into normal nerve development and the genes that direct it.

About one in every 5,000 babies is born with Hirschsprung’s disease, which causes bowel obstruction and can be fatal if not treated. The disease arises early in development when nerves that should control the colon fail to grow properly. Those nerves are part of the enteric nervous system, which is separate from the central nervous system that enables our brains to sense the world.

The genetic causes of Hirschsprung’s disease are complex, making it an interesting case study for researchers like Aravinda Chakravarti, Ph.D., a professor in the Johns Hopkins University School of Medicine’s McKusick-Nathans Institute of Genetic Medicine. His research group took on the condition in 1990, and in 2002, it performed the first-ever genomewide association study to identify common variants linked to the disease.

But while Chakravarti’s and other groups have identified several genetic variants associated with Hirschsprung’s, those variants do not explain most cases of the disease. So Chakravarti and colleagues conducted a new genomewide association study of the disease, comparing the genetic markers of more than 650 people with Hirschsprung’s disease, their parents and healthy controls. One of their findings was a variant in a gene called Ret that had not been previously associated with the disease, although other variations in Ret had been fingered as culprits.

The other finding was of a variant near genes for several so-called semaphorins, proteins that guide developing nerve cells as they grow toward their final targets. Through studies in mice and zebrafish, the researchers found that the semaphorins are indeed active in the developing enteric nervous system, and that they interact with Ret in a system of signals called a pathway.

‘It looks like the semaphorin variant doesn’t by itself lead to Hirschsprung’s, but when there’s a variant in Ret too, it causes the pathway to malfunction and can cause disease,’ Chakravarti says. ‘We’ve found a new pathway that guides development of the enteric nervous system, one that nobody suspected had this role.’

Chakravarti notes that the genetic puzzle of Hirschsprung’s is still missing some pieces, and no clinical genetic test yet exists to assess risk for the disease. Most of the genetic variants that have so far been connected to this rare disease are themselves relatively common and are associated with less severe forms of the disease. The hunt continues for rare variants that can explain more severe cases. EurekAlert