Researchers from the University of Illinois at Urbana-Champaign have developed a highly sensitive biosensor based on a differential immuno-capture technology that can detect sub-populations of white blood cells. As part of a small, disposable biochip, the microfluidic biosensor can count CD4+/CD8+ T cells quickly and accurately for AIDS diagnosis in the field.  

“There are 34 million people infected with HIV/AIDS worldwide, many in places that lack testing facilities,” explained Rashid Bashir, an Abel Bliss Professor of Engineering and head of the Department of Bioengineering at Illinois.

“An important diagnostic biomarker for HIV/AIDS is the absolute count of the CD4+ and CD8+ T lymphocytes in the whole blood. The current diagnostic tool—a flow cytometer—is expensive, requires large blood volume, and a trained technician to operate,” Bashir said. “We have developed a microfluidic biosensor based on a differential immuno-capture electrical cell counting technology to enumerate specific cells in 20 minutes using 10 microliters of blood.” (There are about 50 microliters in a drop of blood). 

Human blood is composed of 45 percent of cells with 5 million erythrocytes as compared to only 7000 leukocytes in one microliter of blood. Specific leukocytes like CD4 T cells are of the order of 50-1000 cells per microliter. Electrical cell counting can differentiate cells based on size and membrane properties depending on the frequency of the interrogation signal. However, differentiating cells of same morphology is a challenge.
“For example, a CD4+ T lymphocyte can’t be differentiated from CD4- lymphocytes just by electrical interrogation,” stated Umer Hassan, a postdoctoral researcher in the Bashir’s group and first author of the paper.

“In response to this challenge, we had developed a technique to selectively deplete target leukocytes,” Hassan added. “And our biochip takes whole blood as input, eliminating the need of off-chip sample preparation and effectively reducing the assay time as well.”

In addition to the microfluidic “capture chamber,” the new chip incorporates separate ports for lysing reagents and quenching buffers that preserve the leukocytes for counting by the microfabricated electrodes. Specific leukocytes like CD4 T cells get captured as they interact with the antibodies in the capture chamber; a  second counter recounts the remaining leukocytes. The difference in the respective cell counts give the concentration of the cells captured.

In clinical trials, the differential immuno-capture biochip achieved more than 90 per cent correlation with a flow cytometer for both CD4 T cells for CD8 T cell counts using HIV infected blood samples. The biochip can also be adapted to enumerate other specific cell types such as somatic cells or cells from tissue or liquid biopsies.

The novel biosensor has the potential to be an automated portable blood cell counter for point-of-care applications in developed and resource-limited regions worldwide. Bashir’s group is working on miniaturizing the setup to make the technology handheld, as well as designing a cartridge that can be mass-produced. Engineering at Illinois

An international team of scientists has identified novel gene locations associated with childhood body mass index (BMI)—an important measurement related to childhood obesity. The meta-analysis, covering over 47,000 children, is the largest genetic study to date of childhood BMI.

“Although investigators have found many genes associated with adult BMI, the genetics of childhood BMI has remained largely unknown,” said Struan F.A. Grant, PhD, a genomics researcher at The Children’s Hospital of Philadelphia (CHOP), and one of three co-senior authors of the study. “Given the fact that childhood obesity is an important concern in public health, identifying specific genetic influences could prove useful in designing future preventive interventions and treatments for children.”

The meta-analysis covered 33 genome-wide association studies, including a total of over 45,000 children, all of European ancestry. Of that total, there were 35,668 children from 20 studies in the discovery phase, and 11,873 children from 13 replication studies. The researchers found 15 genomic regions associated with childhood BMI, three of which were novel.

In all, the 15 risk-susceptibility loci account for 2 percent of the variance in childhood BMI. Despite this small proportion, said Grant, it provides crucial novel insight into the biology of obesity and provides opportunities for generalized therapeutic intervention. The 12 previously discovered genetic loci were shared between both adults and children with high BMI. The large overlap, said the authors, suggests that the genetic variants may not exert their effects only in childhood, but may have different effects at different ages.

Grant added that further research may determine whether the three novel loci the study group discovered influence BMI only in childhood, or whether their effects are stronger during childhood.

The current study, said Grant, dovetails with a 2012 meta-analysis he led for the EGG Consortium. That research was the largest genome-wide study of common childhood obesity. “Obviously, much research remains to be done,” said Grant, who added, “As we continue to identify gene variants implicated in paediatric obesity and body mass, we are laying a foundation for research that could provide useful biological targets for better treating childhood obesity, and its negative health consequences.” The Children’s Hospital of Philadelphia

A new study provides insight on the potential role played by RNA (ribonucleic acid) editing in cancer.

The findings may further our understanding of an emerging mechanism implicated in tumour initiation and progression, and may thus lead to the development of better treatment options in the future.

In every healthy human cell, the genetic information hard-wired into the DNA is transcribed into messenger RNA, which is in turn translated into proteins, the workhorses of all body tissues and organs. The prevailing view is that most malignancies are caused by DNA mutations, which can lead to the aberrant activation or inactivation of the corresponding protein products and to the consequent out-of-control growth and proliferation of malignant cells. RNA editing, the process by which ‘mutations’ of the RNA sequence are introduced post-transcriptionally, has the potential to impact a variety of cellular processes yet the precise mechanism of how has been poorly understood until now.

Previous studies have shown that more than one million sites in the genome are edited to various degrees. Despite the fact that a majority of these editing sites fall within regions that are not translated to protein, it has been shown that the differences in RNA editing levels between tumour and normal tissues are associated with different clinical outcomes. Currently, only a few coding RNA editing sites have been functionally characterized. However, it is still a puzzle whether and how the majority of the RNA editing events in the un-translated regions affect tumour growth.

Researchers from Boston University School of Medicine (BUSM) analysed 14 tumour types, and identified more than 2,000 genes showing significant changes in RNA editing level between tumour and normal tissues.

“This study suggests that RNA editing may serve as an important epigenetic mechanism of cellular regulation beyond the genetic/DNA level,” explained corresponding author Stefano Monti, PhD, associate professor of medicine at BUSM. “We show that the effect of one epigenetic component can be offset by changes in another epigenetic component. Thus, it is important to have a comprehensive picture of changes in the cancer genome, which may point to vulnerabilities amenable to targeted treatment,” added lead author Liye Zhang, PhD, postdoctoral fellow at BUSM. Boston University School of Medicine

Researchers funded by the National Institutes of Health have discovered the cellular switch that boosts the activity of sperm cells so that they can travel to the egg.  The finding may lead to new options for male contraception as well as treatments for infertility resulting from problems with sperm mobility.

Inside the male reproductive tract, mature sperm are capable of limited movement. This limited movement, however, is not enough to propel them toward the egg when they enter the female reproductive tract. To begin their journey, they must first be activated by the hormone progesterone, which is released by the egg.

The researchers report that the molecule to which progesterone must bind is the enzyme alpha/beta hydrolase domain containing protein 2 (ABHD2), found in the sperm cell’s outer membrane. The study was conducted by Melissa R. Miller and colleagues at the University of California, Berkley, the University of California, San Francisco, and Yale University School of Medicine in New Haven, Connecticut.

“This is an important advance in explaining how sperm become hypermotile in the female reproductive tract,” said Stuart Moss, Ph.D, director of the male reproductive health program at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, which funded the study.

“Developing new compounds that block ABHD2 ultimately may yield new contraceptive methods to prevent sperm from reaching the egg.”

Similarly, strategies to bypass or enhance the enzyme might provide therapies for treating infertility resulting from sperm that lack movement capability.

Before a sperm can transition to the hyper-active phase, calcium must pass through the cell’s outer membrane and enter the flagella, the tail-like appendage the cell uses to propel itself.  The sperm protein known as CatSper joins with similar proteins in the flagella to allow the entry of calcium.

When the researchers undertook the current study, it was not known whether progesterone interacted directly with CatSper to trigger the calcium influx, or acted on some other molecule (which, in turn, acted on CatSper). Before treating sperm with progesterone, the researchers exposed them to a chemical that inhibits a particular class of enzymes that they believed could include the candidate molecule that acted on CatSper. The hunch proved correct: the treated cells remained inactive after progesterone exposure, indicating that CatSper was not directly involved.

Working with modified progesterone, the researchers eventually isolated ABHD2 from the sperm tails. When the researchers inactivated ABHD2, exposure to progesterone failed to activate the sperm cells, confirming that ABHD2 is the molecular target for progesterone. Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)

New light has been shed on the genetic relationship between autistic spectrum disorders (ASD) and ASD-related traits in the wider population, by a team of international researchers including academics from the University of Bristol, the Broad Institute of Harvard and MIT, and Massachusetts General Hospital (MGH).

The researchers studied whether there is a genetic relationship between ASD and the expression of ASD-related traits in populations not considered to have ASD. Their findings suggest that genetic risk underlying ASD, including both inherited variants and de novo influences (not seen in an individual’s parents), affects a range of behavioural and developmental traits across the population, with those diagnosed with ASD representing a severe presentation of those traits.

Autism spectrum disorders (ASD) are a class of neurodevelopmental conditions affecting about 1 in 100 children. They are characterised by social interaction difficulties, communication and language impairments, as well as stereotyped and repetitive behaviour. These core symptoms are central to the definition of an ASD diagnosis but also occur, to varying degrees, in unaffected individuals and form an underlying behavioural continuum.

With recent advances in genome sequencing and analysis, a picture of ASD’s genetic landscape has started to take shape. Research has shown that most ASD risk is polygenic (stemming from the combined small effects of thousands of genetic differences, distributed across the genome). Some cases are also associated with rare genetic variants of large effect, which are usually de novo.

 “There has been a lot of strong but indirect evidence that has suggested these findings,” said Dr Mark Daly, co-director of the Broad Institute’s Medical and Population Genetics (MPG) Program and senior author of the study.

“Once we had measurable genetic signals in hand – both polygenic risk and specific de novo mutations known to contribute to ASD – we were able to make an incontrovertible case that the genetic risk contributing to autism is genetic risk that exists in all of us, and influences our behaviour and social communication.”

Study co-first author Dr Elise Robinson, from MGH, said: “We can use behavioural and cognitive data in the general population to untangle the mechanisms through which different types of genetic risk are operating. We now have a better path forward in terms of expecting what types of disorders and traits are going to be associated with certain types of genetic risk.”

“Our study shows that collecting and using phenotypic and genetic data in typically developing children can be useful in terms of the design and interpretation of studies targeting complex neurodevelopmental and psychiatric disorders,’ said study co-first author Dr Beate St Pourcain, from the Medical Research Council Integrative Epidemiology Unit at the University of Bristol and the Max Planck Institute for Psycholinguistics.

“Based on the genetic link between population-based social-communication difficulties and clinical ASD, we may now gain further phenotypic insight into a defined set of genetically-influenced ASD symptoms. This may help us to identify and investigate biological processes in typically-developing children, which are disturbed in children with ASD.” University of Bristol