Headaches, anxiety, irritability—these and other symptoms of nicotine withdrawal can significantly deter smokers from being able to kick the habit. Now, in what may be a significant step toward alleviating those symptoms, UMass Medical School neuroscientist Andrew R. Tapper, PhD, and colleagues have identified the region of the brain in which they originate.
‘We were surprised to find that one population of neurons within a single brain region could actually control physical nicotine withdrawal behaviours,’ said Dr. Tapper, associate professor of psychiatry and interim director of the Brudnick Neuropsychiatric Research Institute at UMMS.
The Tapper lab discovered that physical nicotine withdrawal symptoms are triggered by activation of GABAergic neurons (neurons that secrete GABA, the brain’s predominant inhibitory neurotransmitter), in the interpeduncular nucleus, an area deep in the midbrain that has recently been shown to be involved in nicotine intake.
‘Most of the work in the field has been focused on the immediate effects of nicotine, the addictive component in tobacco smoke, on reward circuits in the brain,’ Tapper explained. ‘But much less is known regarding what happens when you take nicotine away from someone who has been smoking for a long time that causes all these terrible withdrawal symptoms. Our main goal was to understand what brain regions are activated—or deactivated—to cause nicotine withdrawal symptoms.
They did this through a series of experiments performed in mouse models with sophisticated neurochemistry and brain imaging methods, including recently developed optogenetics techniques in which specific neurons can be activated by light.
Most surprising was their discovery that nicotine withdrawal symptoms can be activated or deactivated independent of nicotine addiction. ‘When we activated the GABAergic neurons in the interpeduncular nucleus, mice suffered withdrawal symptoms even if they had no previous nicotine exposure,’ Tapper noted.
These findings are promising because existing treatments intended to help people quit smoking are not always effective. ‘There are very few treatments to help people quit smoking,’ Tapper said. ‘If you can dampen the activity of this brain region chemically during nicotine withdrawal then you would hopefully be able to help someone quit smoking because you could reduce some of the withdrawal symptoms that they are experiencing.’ University of Massachusetts

Massachusetts General Hospital (MGH) investigators have used a new sequencing method to identify a group of genes used by the brain’s immune cells – called microglia – to sense pathogenic organisms, toxins or damaged cells that require their response. Identifying these genes should lead to better understanding of the role of microglia both in normal brains and in neurodegenerative disorders and may lead to new ways to protect against the damage caused by conditions like Alzheimer’s and Parkinson’s diseases. The study also finds that the activity of microglia appears to become more protective with ageing, as opposed to increasingly toxic, which some previous studies had suggested.
‘We’ve been able to define, for the first time, a set of genes microglia use to sense their environment, which we are calling the microglial sensome,’ says Joseph El Khoury, MD, of the MGH Center for Immunology and Inflammatory Diseases and Division of Infectious Diseases, senior author of the study. ‘Identifying these genes will allow us to specifically target them in diseases of the central nervous system by developing ways to upregulate or downregulate their expression.’
A type of macrophage, microglia are known to constantly survey their environment in order to sense the presence of infection, inflammation, and injured or dying cells. Depending on the situation they encounter, microglia may react in a protective manner – engulfing pathogenic organisms, toxins or damaged cells – or release toxic substances that directly destroy microbes or infected brain cells. Since this neurotoxic response can also damage healthy cells, keeping it under control is essential, and excess neurotoxicity is known to contribute to the damage caused by several neurodegenerative disorders.
El Khoury’s team set out to define the transcriptome – the complete set of RNA molecules transcribed by a cell – of the microglia of healthy, adult mice and compared that expression profile to those of macrophages from peripheral tissues of the same animals and of whole brain tissue. Using a technique called direct RNA sequencing, which is more accurate than previous methods, they identified a set of genes uniquely expressed in the microglia and measured their expression levels, the first time such a gene expression ‘snapshot’ has been produced for any mammalian brain cell, the authors note.
Since ageing is known to alter gene expression throughout the brain, the researchers then compared the sensome of young adult mice to that of aged mice. They found that – contrary to what previous studies had suggested – the expression of genes involved in potentially neurotoxic actions, such as destroying neurons, was down-regulated as animals aged, while the expression of neuroprotective genes involved in sensing and removing pathogens was increased. El Khoury notes that the earlier studies suggesting increased neurotoxicity with ageing did not look at the cells’ full expression profile and often were done in cultured cells, not in living animals.
‘Establishing the sensome of microglia allows us to clearly understand how they interact with and respond to their environment under normal conditions,’ he explains. ‘The next step is to see what happens under pathologic conditions. We know that microglia become more neurotoxic as Alzheimer’s disease and other neurodegenerative disorders progress, and recent studies have identified two of the microglial sensome genes as contributing to Alzheimer’s risk. Our next steps should be defining the sensome of microglia and other brain cells in humans, identifying how the sensome changes in central nervous system disorders, and eventually finding ways to safely manipulate the sensome pharmacologically.’ Massachusetts General Hospital

Viruses cannot only cause illnesses in humans, they also infect bacteria. Those protect themselves with a kind of ‘immune system’ which – simply put – consists of specific sequences in the genetic material of the bacteria and a suitable enzyme. It detects foreign DNA, which may originate from a virus, cuts it up and thus makes the invaders harmless. Scientists from the Helmholtz Centre for Infection Research (HZI) in Braunschweig have now shown that the dual-RNA guided enzyme Cas9 which is involved in the process has developed independently in various strains of bacteria. This enhances the potential of exploiting the bacterial immune system for genome engineering.
Even though it has only been discovered in recent years the immune system with the cryptic name ‘CRISPR-Cas’ has been attracting attention of geneticists and biotechnologists as it is a promising tool for genetic engineering. CRISPR is short for Clustered Regularly Interspaced Palindromic Repeats, whereas Cas simply stands for the CRISPR-associated protein. Throughout evolution, this molecule has developed independently in numerous strains of bacteria. This is now shown by Prof Emmanuelle Charpentier and her colleagues at the Helmholtz Centre for Infection Research (HZI) who published their finding in the international open access journal Nucleic Acids Research.

The CRISPR-Cas-system is not only valuable for bacteria but also for working in the laboratory. It detects a specific sequence of letters in the genetic code and cuts the DNA at this point. Thus, scientists can either remove or add genes at the interface. By this, for instance, plants can be cultivated which are resistant against vermins or fungi. Existing technologies doing the same thing are often expensive, time consuming or less accurate. In contrast to them the new method is faster, more precise and cheaper, as fewer components are needed and it can target longer gene sequences.

Additionally, this makes the system more flexible, as small changes allow the technology to adapt to different applications. ‘The CRISPR-Cas-system is a very powerful tool for genetic engineering,’ says Emmanuelle Charpentier, who came to the HZI from Umeå and was awarded with the renowned Humboldt Professorship in 2013. ‘We have analysed and compared the enzyme Cas9 and the dual-tracrRNAs-crRNAs that guide this enzyme site-specifically to the DNA in various strains of bacteria.’ Their findings allow them to classify the Cas9 proteins originating from different bacteria into groups. Within those the CRISPR-Cas systems are exchangeable which is not possible between different groups.

This allows for new ways of using the technology in the laboratory: The enzymes can be combined and thereby a variety of changes in the target-DNA can be made at once. Thus, a new therapy for genetic disorders caused by different mutations in the DNA of the patient could be on the horizon. Furthermore, the method could be used to fight the AIDS virus HIV which uses a receptor of the human immune cells to infect them. Using CRISPR-Cas, the gene for the receptor could be removed and the patients could become immune to the virus. However, it is still a long way until this aim will be reached.

Still those examples show the huge potential of the CRISPR-Cas technology. ‘Some of my colleagues already compare it to the PCR,’ says Charpentier. This method, developed in the 1980s, allows scientists to ‘copy’ nucleic acids and therefore to manifold small amounts of DNA to such an extent that they can be analysed biochemically. Without this ground-breaking technology a lot of experiments we consider to be routine would have never been possible. Helmholtz Ceentre for Infection Research

A team of researchers from UCLA and Harvard University have demonstrated a technique that, by measuring the physical properties of individual cells in body fluids, can diagnose cancer with a high degree of accuracy.
The technique, which uses a deformability cytometer to analyse individual cells, could reduce the need for more cumbersome diagnostic procedures and the associated costs, while improving accuracy over current methods. The initial clinical study analysed pleural fluid samples from more than 100 patients.
Pleural fluid, a natural lubricant of the lungs as they expand and contract during breathing, is normally present in spaces surrounding the lungs. Medical conditions such as pneumonia, congestive heart failure and cancer can cause an abnormally large buildup of the fluid, which is called a pleural effusion.
When cytopathologists screen for cancer in pleural effusions, they perform a visual analysis of prepared cells extracted from the fluid. Preparing cells for this analysis can involve complicated and time-consuming dyeing or molecular labelling, and the tests often do not definitively determine the presence of tumour cells. As a result, additional costly tests often are required.
The method in the UCLA–Harvard study, developed previously by the UCLA researchers, requires little sample preparation, relying instead on the imaging of cells as they flow through in microscale fluid conduits.
Imagine squeezing two balloons, one filled with water and one filled with honey. The balloons would feel different and would deform differently in your grip. The researchers used this principle on the cellular level by using a fluid grip to ‘squeeze’ individual cells that are 10,000 times smaller than balloons—a technique called ‘deformability cytometry.’ The amount of a cell’s compression can provide insights about the cell’s makeup or structure, such as the elasticity of its membrane or the resistance to flow of the DNA or proteins inside it. Cancer cells have a different architecture and are softer than healthy cells and, as a result, ‘deform’ differently.
Using deformability cytometry, researchers can analyse more than 1,000 cells per second as they are suspended in a flowing fluid, providing significantly more detail on the variations within each patient’s sample than could be detected using previous physical analysis techniques.
The researchers also noted that the more detailed information they obtained improved the sensitivity of the test: Some patient samples that were not identified as cancerous via traditional methods were found to be so through deformability cytometry. These results were verified six months later.

‘Building off of these results, we are starting studies with many more patients to determine if this could be a cost-effective diagnostic tool and provide even more detailed information about cancer origin,’ said Dino Di Carlo, associate professor of bioengineering at the UCLA Henry Samueli School of Engineering and Applied Science and a co-principal investigator on the research. ‘It could help to reduce laboratory workload and accelerate diagnosis, as well as offer doctors a new way to improve clinical decision-making.’ University of California – Los Angeles

In light of new research, Dr André Lacroix suggests genetic screening to find ‘silent carriers’.
Genetic research suggests to Dr. André Lacroix, professor at the University of Montreal, that clinicians’ understanding and treatment of a form of Cushing’s syndrome affecting both adrenal glands will be fundamentally changed, and that moreover, it might be appropriate to begin screening for the genetic mutations that cause this form of the disease. ‘Screening family members of bilateral adrenal Cushing’s syndrome patients with genetic mutations may identify affected silent carriers,’ Lacroix said ‘The development of drugs that interrupt the defective genetic chemical link that causes the syndrome could, if confirmed to be effective in people, provide individualised specific therapies for hypercortisolism, eliminate the current practice of removing both adrenal glands, and possibly prevent disease progression in genetically affected family members.’ Adrenal glands sit above the kidneys are mainly responsible for releasing cortisol, a stress hormone. Hypercortiolism means a high level of the adrenal hormone cortisol, which causes many symptoms including weight gain, high blood pressure, diabetes, osteoporosis, concentration deficit and increased cardiovascular deaths.

Cushing’s syndrome can be caused by corticosteroid use (such as for asthma or arthritis), a tumour on the adrenal glands, or a pituitary gland that releases too much ACTH. The pituitary gland sits under the brain and releases various hormones that regulate our bodies’ mechanisms.

Jérôme Bertherat is a researcher at Cochin Hospital in Paris. In the study he showed that 55% of Cushing’s Syndrome patients with bilaterally very enlarged adrenal glands have mutations in a gene that predisposes to the development of adrenal tumours. This means that bilateral adrenal Cushing’s is much more hereditary than previously thought. The new knowledge will also enable clinicians to undertake genetic screening. Hervé Lefebvre is a researcher at the University Hospital in Rouen, France. His research shows that the adrenal glands from the same type of patients with two large adrenal glands can produce ACTH, which is normally produced by the pituitary gland. Hormone receptors are the chemical link that cause a cell to behave differently when a hormone is present. Several misplaced hormone receptors cause the ACTH to be produced in the enlarged benign adrenal tissue. Knowing this means that researchers might be able to develop drugs that interrupt the receptors for these hormones and possibly even prevent the benign tissue from developing in the first place. Université de Montréal.