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Mar 30
Scientists develop first mouse model to battle Zika virus
In what can be called as a tremendous development in the field of medicine, a team of scientists from the US have developed first animal model for testing vaccines and drugs to fight Zika virus.

An able team of researchers from the University of Texas Medical Branch have been successful in coming up with the first mouse model that will speed up Zika drug development. This research has already yielded a few clues about the virus' pathogenesis.

Lead author Shannan Rossi said that there is a huge demand to screen antivirals that have been backlogged because we haven't had a good way to test them, adding "Without this model, we were really stagnant in our efforts to find new treatments. You can look for efficacy in cell cultures, but that tells you almost nothing about what's going to happen when you test in a mouse or a human. This will help get those drug and vaccine candidates moving through the pipeline."

"Normally, creating a mouse model like this would take us several months, but the urgency of the situation propelled us into this rapid response, and we were able to put together our results in just three weeks," Rossi said.

Rossi injected several genetically distinct varieties of laboratory mice with Zika virus isolated in Asia in 2010. The current epidemic in South America can be traced to the Asian Zika virus lineage, of which this strain is a member.

Normal mice did not develop disease after infection with Zika virus, the research team reported. Only when researchers injected mice that had been genetically altered to have a deficient innate immune response did the animals develop detectible disease. Young mice of these strains are highly susceptible to infection. These mice became lethargic, lost weight and died within six days after infection. Older mice became ill, but did not always develop infection, and they ultimately recovered.

The mouse model is available immediately for testing of antivirals and researcher Scott Weaver said that preliminary testing is already underway with an antiviral developed by another member of the UTMB team, Pei-Yong Shi, PhD, to treat dengue fever.

Mar 29
Most female childhood cancer survivors able to conceive
Most women who have survived childhood cancer have a good chance of conceiving as the impact of modern chemotherapy regimens on the likelihood of becoming pregnant is generally small, says a study.

In contrast, male survivors of childhood cancer are significantly less likely to have children, especially if they are treated with chemotherapy regimens containing high doses of commonly used alkylating drugs and cisplatin, the findings showed.

"We think these results will be encouraging for most women who were treated with chemotherapy in childhood," said one of the researchers Eric Chow from the Fred Hutchinson Cancer Research Centre, Seattle, US.

The study was published in the journal The Lancet Oncology.

For the study, the researchers used data from the Childhood Cancer Survivor Study (CCSS) which tracks people who were diagnosed with the most common types of childhood cancer before the age of 21 and treated at 27 institutions across the USA and Canada between 1970 and 1999, and who had survived at least five years after diagnosis.

In this study, they examined the impact of various doses of 14 commonly used chemotherapy drugs on pregnancy and livebirth in 10,938 male and female survivors, compared with 3,949 siblings.

The study specifically focused on survivors treated with chemotherapy and who did not receive any radiotherapy to the pelvis or the brain.

By age 45, 70 percent of female cancer survivors became pregnant, compared to over 80 percent of siblings.

For male cancer survivors, the figure was 50 percent compared to 80 percent for siblings.

In male survivors, the likelihood of fathering a child generally decreased as cumulative exposure to alkylating drugs increased.

The findings are consistent with previous studies which have suggested that men who have undergone cancer treatment with these drugs have lower sperm count and reduced testicular volume.

Overall, female survivors were still less likely to conceive compared to siblings but the effect was much smaller compared to men.

Mar 28
Marijuana users react differently to social exclusion
The brains of young adult marijuana users react differently to social exclusion than do those of non-users, finds a new study, adding that young adults who regularly use marijuana display altered brain activation patterns during social exclusion.

The brains of young adults who smoke marijuana two to four times a week were less likely to react to social exclusion than the brains of non-users.

"Peer groups are one of the most important predictors of young adult marijuana use, and yet we know very little about the neural correlates of social rejection in those who use marijuana," said lead author Jodi Gilman, assistant professor at Harvard Medical School in US.

During peer rejection, young adult marijuana users reduced activation in the insula, a brain region usually active during social rejection, which may reflect the impaired processing of social information in marijuana users.

Reduced activity in the insula to peer rejection could indicate that marijuana users are less conscious of social norms, or have reduced capacity to reflect or react to negative social situations.

"The unexpected reduction in insula response may indicate that marijuana users are less conscious of social norms or have reduced ability to reflect on negative social situations," explained Gilman.

The findings were detailed in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.

The team conducted a magnetic resonance study using a Cyberball task -- a computerised tool that is typically used to assess people's reaction to social exclusion, such as a rejection or ostracism -- where participants played a computerised game of catch while undergoing a non-invasive brain scan.

They enrolled 42 young adults aged 18 to 25, out of which 20 reported using marijuana two to four times a week and 22 reported no recent marijuana use.

Unknown to the study participants, the other "players" in the game were computers and were programmed to exclude them for a portion of the game.

They focused on three brain regions of participants that previous studies have associated with the response to social exclusion - the anterior insula, the ventral anterior cingulate cortex (vACC) -- the region involved in decision-making and emotional regulation and regulates physiological processes, such as blood pressure and heart rate and the orbitofrontal cortex (OFC) -- the region involved only in decision-making.

The team found that for the control group of non-marijuana users, there was activation in the vACC and the insula during the exclusion portion of the game. For the users, the researchers found activation in the vACC but none in the insula. The researchers observed no significant activity in the OFC in both groups.

More research is imperative to assess the developmental trajectory of this altered social processing and determine whether impaired processing of social exclusion is caused by, is a result of, or develops along with marijuana use, the researchers concluded.

Mar 26
Prolonged daily sitting causes four percent of deaths globally: Study
Sitting for more than three hours per day is responsible for nearly four percent of deaths in the world, shows an analysis of surveys from 54 countries around the world.

Reducing sitting time to less than three hours per day would increase life expectancy by an average of 0.2 years, the researchers estimated.

In order to properly assess the damaging effects of sitting, the study analysed behavioural surveys from 54 countries around the world and matched them with statistics on population size, actuarial table and overall deaths.

Researchers found that sitting time significantly impacted all-cause mortality, accounting for approximately 433,000, or 3.8 percent, of all deaths across the 54 nations in the study.

They also found that sitting had higher impact on mortality rates in the Western Pacific region, followed by European, Eastern Mediterranean, American, and Southeast Asian countries, respectively.

The findings were published in the American Journal of Preventive Medicine.

While researchers found that sitting contributed to all-cause mortality, they also estimated the impact from reduced sitting time independent of moderate to vigorous physical activity.

"It was observed that even modest reductions, such as a 10 percent reduction in the mean sitting time or a 30-minute absolute decrease of sitting time per day, could have an instant impact in all-cause mortality in the 54 evaluated countries, whereas bolder changes (for instance, 50 percent decrease or two hours fewer) would represent at least three times fewer deaths versus the 10 percent or 30-minute reduction scenarios," explained lead investigator Leandro Rezende from the University of Sao Paulo School of Medicine in Brazil.

Mar 25
High-intensity workout may hurt you if you are new to gym
Have you just joined a gym and already started a high-intensity "sprint training" workout? A new study has found signs of stress in the muscle tissues of non-athletes and untrained people after ultra-intense leg and arm cycling exercises which might not be healthy.

Researchers found untrained people had a weakened ability to fight off free radicals -- molecules that can alter DNA and harm healthy cells -- that may increase the risk of cancer, premature aging and organ damage.

Beginners start slowly and gradually increase intensity over time, under the supervision of a trained professional or kinesiologist, the authors suggested.

"Our study raises questions about what the right dose and intensity of exercise for the average person really is," said senior study author Robert Boushel from University of British Columbia's school of Kinesiology in Canada.

"We need to be cautious about supporting sprint training in the general population," Boushel added in the paper published in the Federation of American Societies for Experimental Biology Journal.

The researchers analysed tissue samples from their test the participants and found that their mitochondria -- the powerhouse of cells -- were only firing at half-power post-training, reducing their capacity to consume oxygen and their ability to fight off damage from free radicals.

"If you're new to going to the gym, participating in high-intensity 'sprint' classes may increase your performance but might not be healthy for you," said Boushel.

Seasoned athletes and those who are well trained have built up antioxidant enzymes in their bodies to protect against free radicals, said Boushel.

The study was carried out in a dozen male volunteers in Sweden, all of whom were in good health but self-identified as untrained or only moderately active.

The men participated in high-intensity training over the course of two weeks that involved repeated 30-second all-out sprints, followed by rest periods.

The study, high-intensity sprint training inhibits mitochondrial respiration through aconitase inactivation.

Mar 22
New blood test may detect multiple diseases
Scientists have developed a new blood test that may detect multiple diseases, including diabetes, cancer, traumatic injury and neuro degeneration, in a highly sensitive and specific manner.

The novel method, developed in a series of experiments involving 320 patients and controls, infers cell death in specific tissue from the methylation patterns of circulating DNA that is released by dying cells.

Cell death is a central feature of human biology in health and disease, according to researchers led by Ruth Shemer and Yuval Dor from The Hebrew University of Jerusalem, and Benjamin Glaser from Hadassah Medical Centre.

It can signify the early stages of pathology (eg a developing tumour or the beginning of an autoimmune or neurodegenerative disease), mark disease progression, reflect the success of therapy (eg anti cancer drugs), identify unintended toxic effects of treatment and more.

However to date, it is not possible to measure cell death in specific human tissues non-invasively.

The new blood test detects cell death in specific tissues by combining two important biological principles. First, dying cells release fragmented DNA to the circulation, where it travels for a short time.

The second principle is that the DNA of each cell type carries a unique chemical modification called methylation.

Methylation patterns of DNA account for the identity of cells (the genes that they express), are similar among different cells of the same type and among individuals, and are stable in healthy and disease conditions.

For example, the DNA methylation pattern of pancreatic cells differs from the pattern of all other cell types in the body.

The researchers have identified multiple DNA sequences that are methylated in a tissue-specific manner (for example, unmethylated in DNA of neurons and methylated elsewhere), and can serve as biomarkers for the detection of DNA derived from each tissue.

They then developed a method to detect these methylated patterns in DNA circulating in blood, and demonstrated its utility for identifying the origins of circulating DNA in different human pathologies, as an indication of cell death in specific tissues.

They were able to detect evidence for pancreatic beta-cell death in the blood of patients with new-onset type 1 diabetes, oligodendrocyte death in patients with relapsing multiple sclerosis, brain cell death in patients after traumatic or ischemic brain damage, and exocrine pancreas cell death in patients with pancreatic cancer or pancreatitis.

"Our work demonstrates that the tissue origins of circulating DNA can be measured in humans. This represents a new method for sensitive detection of cell death in specific tissues, and an exciting approach for diagnostic medicine," said Shemer.

The findings were published in the journal PNAS.

Mar 21
Omega-3 supplementation linked to reduction in depression
Omega-3 fatty acids play a critical role in the development and function of the central nervous system, say British scientists who found a link between Omega-3 supplementation and reduction in depression.

A new meta-analysis by British researchers supports the link between intake of EPA and DHA omega-3 fatty acids -- the kind found in fish -- and reduction in major depressive disorder (MDD).

The meta-analysis includes 13 studies with 1,233 participants.

The findings showed a benefit for EPA and DHA comparable to effects reported in meta-analyses of anti-depressants.

The effect was greater in studies supplementing higher doses of EPA and performed in patients already on anti-depressants.

The paper was published in the journal Translational Psychiatry.

"This new meta-analysis nuances earlier research on the importance of long chain omega-3s in MDD," said lead study author R.J.T. Mocking from the University of Amsterdam, the Netherlands.

Mar 19
Alcohol smell tempts us into boozing
Why is alcohol so addictive? According to a new study, for some people, the mere smell of booze can send them on a downwards spiral towards dependency.

The Edge Hill University researchers found that the smell of alcohol may make it harder for people to control their behaviour.

During the computer-based study, participants were asked to wear a face mask that was either laced with alcohol, or a non-alcoholic citrus solution. Participants were then instructed to press a button when either the letter K or a picture of a beer bottle appeared on their screen.

The researchers measured the number of times the participants incorrectly pressed the button causing a 'false alarm'. These false alarms indicate a reduction in the participant's power to inhibit their behaviour when they were expected to.

Dr. Rebecca Monk said that the team found that the number of these 'false alarms' were higher in participants who were wearing the alcohol treated mask, adding ""We know that alcohol behaviours are shaped by our environment including who we're with and the settings in which we drink."

Monk noted that this research is a first attempt to explore other triggers, such as smell, that may interfere with people's ability to refrain from a particular behaviour. For example, during the experiment it seemed that just the smell of alcohol was making it harder for participants to control their behaviour to stop pressing a button.

Researcher Derek Heim said that their hope is that by increasing the understanding of how context shapes substance-use behaviours, they will be able to make interventions more sensitive to the different situations in which people consume substances.

The study is published in the Psychopharmacology journal.

Mar 18
3D printing may heal damaged cartilage in knees, ears
Scientists have found a way to produce cartilage tissue by 3D bioprinting an ink containing human cells, that may lead to personalised implants to heal damaged noses, ears and knees.

The researchers have successfully tested the technology in an in vivo mouse model. Athletes, the elderly and others who suffer from injuries and arthritis can lose cartilage and experience a lot of pain.

"Three-dimensional bioprinting is a disruptive technology and is expected to revolutionise tissue engineering and regenerative medicine," said Paul Gatenholm, from Wallenberg Wood Science Centre in Sweden.

"Our team's interest is in working with plastic surgeons to create cartilage to repair damage from injuries or cancer," said Gatenholm. "We work with the ear and the nose, which are parts of the body that surgeons today have a hard time repairing. But hopefully, they'll one day be able to fix them with a 3D printer and a bioink made out of a patient's own cells," he said.

The researchers first had to develop an ink with living human cells that would keep its shape after printing.

To create a new bioink, they mixed polysaccharides from brown algae and tiny cellulose fibrils from wood or made by bacteria, as well as human chondrocytes, which are cells that build up cartilage.

Using this mixture, the researchers were able to print living cells in a specific architecture, such as an ear shape, that maintained its form even after printing. The printed cells also produced cartilage in a laboratory dish.

"But under in vitro conditions, we have to change the nutrient-filled liquid that the material sits in every other day and add growth factors," Gatenholm said.

The next step was to move the research from a lab dish to a living system. The team printed tissue samples and implanted them in mice. The cells survived and produced cartilage. To boost the number of cells, the researchers mixed the chondrocytes with human mesenchymal stem cells from bone marrow.

Previous research has indicated that stem cells spur primary cells to proliferate more than they would alone. Preliminary data from in vivo testing over 60 days show the combination does indeed encourage chondrocyte and cartilage production.

Mar 17
Generic drug can reduce treatment cost for cancer patients
Patients suffering from chronic myeloid leukemia (CML)-- a rare form of cancer -- can get huge financial benefits if they start using the generic form of drug Gleevec, the patent of which expired in January this year, a study said.

"If we start all patients on the generic form of Gleevec and it works, then they are on a generic for the rest of their lives," said lead author William V. Padula, an assistant professor at the Johns Hopkins University. "This amounts to a huge cost savings for them and their insurers," he added.

The study, published recently in the Journal of the National Cancer Institute, said if all CML patients were started upon diagnosis on the generic form of Gleevec, known as imatinib, the cost of treatment per patient over five years would be nearly $100,000 less than it is now.

While Gleevec was the first drug to successfully treat CML, two other drugs in the same category - dasatinib (sold as Sprycel) and nilotinib (sold as Tasinga) - have come on the market in recent years.

Generic versions of these drugs will not be available for many years and the branded versions cost roughly $75,000 each for a year's supply.

In nearly 90 percent of cases, patients are now started on one of these newer drugs based on each physician's preference, but research has shown that overall five-year survival rates of all three drugs are equivalent.

Padula's team found that if insurers decided to only pay for Gleevec as the first line drug -- instead of allowing doctors to choose -- the savings would be even greater than $100,000 over five years if the patient stayed on Gleevec for the entire time.

This five-year time point is significant since it is the amount of time hematologists and oncologists typically use to measure progression-free survival or overall survival from remission in CML patients.

"There is minimal risk to starting all patients on imatinib first," Padula said.

"If the patient can't tolerate the medication or it seems to be ineffective in that patient, then we can switch the patient to a more expensive drug. Insurance companies have the ability to dictate which drugs physicians prescribe first, and they regularly do. Doing so here would mean very little risk to health and a lot of cost savings," he added.