Newly developed test can identify sickle cell disease in minutes and could be used in rural clinics around the globe
Within minutes after birth, every child in the U.S. undergoes a battery of tests designed to diagnose a host of conditions, including sickle cell disease. Thousands of children born in the developing world, however, aren’t so lucky, meaning many suffer and die from the disease each year.
A.J. Kumar hopes to put a halt to at least some of those deaths.
A Post-Doctoral Fellow in Chemistry and Chemical Biology working in the lab of George Whitesides, the Woodford L. and Ann A. Flowers University Professor, Kumar and colleagues, including other co-authors, have developed a new test for sickle cell disease that provides results in just 12 minutes and costs as little as 50 cents – far faster and cheaper than other tests.
‘The tests we have today work great, they have a very high sensitivity,’ Kumar said. ‘But the equipment needed to run them costs in the tens of thousands of dollars, and they take hours to run. That’s not amenable to rural clinics, or even some cities where the medical infrastructure isn’t up to the standards we see in the U.S. That’s where having a rapid, low-cost test becomes important and this paper shows such a test can potentially work.’
When run against more than 50 clinical samples – 26 positive and 26 negative – the new test showed good sensitivity and specificity for the disease, Kumar said, so the early evidence is promising, but additional testing will be needed to determine whether the test is truly accurate enough to use in the field.
The test designed by Kumar is deceptively simple, and works by connecting two ideas scientists have understood for decades.
The first is the notion that blood cells affected by the disease are denser than normal cells, and the second is that many polymers, when mixed in water, automatically separate into layers ordered by density.
Conventional methods to separate cells by density relied on layering liquids with different density by hand. The insight, arrived at by Charles Mace (now at Tufts) and Kumar, was that the self-forming layers could be used to separate cells, such as red blood cells, by density.
‘When you mix the polymers with water, they separate just like oil and water,’ he said. ‘Even if you mix it up, it will still come back to those layers.’
It wasn’t until a chance meeting with Dr. Thomas Stossel, however, that Kumar believed the technology might have a real impact on sickle cell disease.
‘Initially, we started off working on malaria, because we thought when parasites invaded the cells, it would change their density,’ he said. ‘But when I met Tom Stossel on a panel at the Harvard Medical School, he said, ‘You need to work on sickle cell.’ He’s a haematologist by training and has been working with a non-profit in Zambia for the past decade, so he’s seen the need and the lack of a diagnostic tool.’
When Kumar and colleagues ran tests with infected blood, their results were unmistakable. While healthy red blood cells settled in the tubes at specific levels, the dense cells from blood infected with sickle cell settled in a band significantly lower. The band of red cells could clearly be seen by eye.
Just showing that the test worked, however, wasn’t enough.
‘We wanted to make the test as simple as possible,’ Kumar explained. ‘The idea was to make it something you could run from just a finger prick. Because these gradients assemble on their own, that meant we could make them in whatever volume we wanted, even a small capillary tube.’
The design the team eventually settled on is barely larger than a toothpick. In the field, Kumar said, running the test is as simple as uncapping the tube, pricking a patient’s finger and allowing the blood to wick into the tube.
While further study is needed to determine how accurate and effective the test may be, Kumar said stopping even a few sickle-cell-related deaths would
EurekAlert
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A study by researchers at the University of Kansas shows a new role for the protein adenomatous polyposis coli (APC) in suppressing colorectal cancer — the second-leading cause of cancer-related deaths in the U.S.
Lead author Kristi Neufeld, associate professor in the Department of Molecular Biosciences and co-leader of the Cancer Biology program at the KU Cancer Center, has spent the better part of her career trying to understand the various activities of APC, a protein whose functional loss is thought to initiate roughly 80 percent of all colon polyps, a precursor to colon cancer. Neufeld, along with her postdoctoral fellow Maged Zeineldin, undergraduate student Mathew Miller and veterinary pathologist Ruth Sullivan, now reports that APC found in a particular subcellular compartment, the nucleus, protects from inflammation as well as tumour development associated with chronic colitis.
Whether APC reaches the nucleus may well affect the ability of intestinal stem cells to produce differentiated cells with specialized functions, Neufeld said.
“It’s not widely appreciated, but there is still plenty of cell growth going on in adults, with the colon being a good example,” she said. “On average, we shed and replace about 70 pounds of intestinal tissue annually, so you can imagine that this process requires exquisite control to prevent tumour formation.”
Regular renewal of the colon lining occurs through stem cells that are capable of constantly dividing. These cells produce descendants that take up specific roles: By secreting mucin, for instance, goblet cells generate a mucus layer that serves as the colon’s physical barrier against its many microbial tenants. But if APC can’t find its way to the nucleus, Neufeld and her team have noted far fewer goblet cells as one outcome.
“We introduced a specific APC mutation into mice that took away the nuclear zip code, so to speak, leaving APC stuck in the cytoplasm,” Neufeld said. The researchers studied this mouse model under conditions that induce ulcerative colitis, a form of inflammatory bowel disease that can be a prelude to colon cancer.
Observing significantly more colon tumours in these mice compared to those with normal APC in the same disease setting, they hypothesized that functional nuclear APC might somehow guard against inflammation and its downstream effects, including tumour development. Now, Neufeld thinks she and her team may have a clue as to how this happens.
“The drop in goblet cell numbers we observed was striking,” she said. “We then examined one of the proteins found in mucus, called Muc2, and found that its RNA levels were greatly decreased. If there are fewer goblet cells as a result of APC being unable to reach the nucleus, there will also be less mucus, which could increase the colon’s sensitivity to bacteria and other microorganisms in the gut that are capable of promoting inflammation.”
Neufeld said while there are still no quick fixes for mutant genes, perhaps tools could be developed to synthetically replace this less-than-ideally thick mucus layer in affected people.
One known function of APC is that it halts cell proliferation: by muzzling the canonical arm of the Wnt signaling pathway, which otherwise instructs cells to go forth and multiply. Neufeld and her group have already shown, using the same mouse model, that APC stationed in the nucleus is necessary to suppress Wnt and its signaling partners — particularly β-catenin, a key target of normal APC. With a role for nuclear APC in controlling goblet cell differentiation now supported, the researchers are probing possible mechanisms to learn if and how Wnt pathway members might be involved.
Kansas University
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A newborn screening test for severe combined immunodeficiency (SCID) reliably identifies infants with this life-threatening inherited condition, leading to prompt treatment and high survival rates, according to a study supported by the National Institutes of Health. Researchers led by Jennifer Puck, M.D., of the University of California, San Francisco, also found that SCID affects approximately 1 in 58,000 newborns, indicating that the disorder is less rare than previously thought. The study was funded in part by NIH’s National Institute of Allergy and Infectious Diseases (NIAID) and Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).
SCID is a group of disorders caused by defects in genes involved in the development and function of T cells and other infection-fighting immune cells. Infants with SCID are highly susceptible to life-threatening infections. SCID is fatal, usually within the first year or two of life, unless affected infants are given immune-restoring treatments such as transplants of blood-forming stem cells or gene therapy. More than 80 percent of affected infants do not have a family history of the condition.
“The results of this study highlight the important role of newborn screening for SCID,” said NIAID Director Anthony S. Fauci, M.D. “The findings demonstrate that detecting SCID before symptoms such as severe infections appear helps ensure that infants with this serious condition receive lifesaving treatments.”
The SCID newborn screening test, originally developed at NIH, measures T cell receptor excision circles (TRECs), a by-product of T-cell development. Infants with SCID have few or no T cells, regardless of the underlying genetic defect, and the absence of TRECs may indicate SCID. The TREC test also may help doctors identify infants with non-SCID T-cell deficiencies. SCID was added in 2010 to the U.S. Department of Health and Human Services’ Recommended Uniform Screening Panel for newborns in the United States. However, the TREC test has not yet been adopted universally. Nearly half of states conduct newborn screening for SCID, and the test is performed for almost two thirds of infants born across the country.
“We have made great strides in our knowledge of SCID and other related immunodeficiencies in a relatively short period of time, thanks to newborn screening,” said Tiina Urv, Ph.D., a program director in the Intellectual and Developmental Disabilities Branch at NICHD. “Such collaborative research efforts could serve as a model for other disorders.”
Eunice Kennedy Shriver National Institute of Child Health and Human Development
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Over the past several decades, malaria diagnosis has changed very little. After taking a blood sample from a patient, a technician smears the blood across a glass slide, stains it with a special dye, and looks under a microscope for the Plasmodium parasite, which causes the disease. This approach gives an accurate count of how many parasites are in the blood — an important measure of disease severity — but is not ideal because there is potential for human error.
A research team from the Singapore-MIT Alliance for Research and Technology (SMART) has now come up with a possible alternative. The researchers have devised a way to use magnetic resonance relaxometry (MRR), a close cousin of magnetic resonance imaging (MRI), to detect a parasitic waste product in the blood of infected patients. This technique could offer a more reliable way to detect malaria, says Jongyoon Han, a professor of electrical engineering and biological engineering at MIT.
“There is real potential to make this into a field-deployable system, especially since you don’t need any kind of labels or dye. It’s based on a naturally occurring biomarker that does not require any biochemical processing of samples” says Han, one of the senior authors of a paper describing the technique.
With the traditional blood-smear technique, a technician stains the blood with a reagent that dyes cell nuclei. Red blood cells don’t have nuclei, so any that show up are presumed to belong to parasite cells. However, the technology and expertise needed to identify the parasite are not always available in some of the regions most affected by malaria, and technicians don’t always agree in their interpretations of the smears, Han says.
“There’s a lot of human-to-human variation regarding what counts as infected red blood cells versus some dust particles stuck on the plate. It really takes a lot of practice,” he says.
The new SMART system detects a parasitic waste product called haemozoin. When the parasites infect red blood cells, they feed on the nutrient-rich haemoglobin carried by the cells. As haemoglobin breaks down, it releases iron, which can be toxic, so the parasite converts the iron into hemozoin — a weakly paramagnetic crystallite.
Those crystals interfere with the normal magnetic spins of hydrogen atoms. When exposed to a powerful magnetic field, hydrogen atoms align their spins in the same direction. When a second, smaller field perturbs the atoms, they should all change their spins in synchrony — but if another magnetic particle, such as hemozoin, is present, this synchrony is disrupted through a process called relaxation. The more magnetic particles are present, the more quickly the synchrony is disrupted.
“What we are trying to really measure is how the hydrogen’s nuclear magnetic resonance is affected by the proximity of other magnetic particles,” Han says.
For this study, the researchers used a 0.5-tesla magnet, much less expensive and powerful than the 2- or 3-tesla magnets typically required for MRI diagnostic imaging, which can cost up to $2 million. The current device prototype is small enough to sit on a table or lab bench, but the team is also working on a portable version that is about the size of a small electronic tablet.
After taking a blood sample and spinning it down to concentrate the red blood cells, the sample analysis takes less than a minute. Only about 10 microliters of blood is required, which can be obtained with a finger prick, making the procedure minimally invasive and much easier for health care workers than drawing blood intravenously.
“This system can be built at a very low cost, relative to the million-dollar MRI machines used in a hospital,” Peng says. “Furthermore, since this technique does not rely on expensive labelling with chemical reagents, we are able to get each diagnostic test done at a cost of less than 10 cents.”
MIT
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A new blood test provides a fast and accurate tool to diagnose tuberculosis in children, a new proof-of-concept study shows. The newly developed test (TAM-TB assay) is the first reliable immunodiagnostic assay to detect active tuberculosis in children. The test features excellent specificity, a similar sensitivity as culture tests in combination with speed of a blood test. The promising findings are a major advance for the diagnosis of tuberculosis in children, particularly in tuberculosis-endemic regions.
Tuberculosis (TB) in children is a serious public health problem especially in low-resource countries. About one million children per year develop tuberculosis worldwide. Unfortunately, the diagnosis of paediatric TB poses a major challenge. TB symptoms in children are often non-specific and similar to those of common paediatric illnesses, including pneumonia and malnutrition. Further, obtaining adequate respiratory specimens for direct mycobacterial confirmation is problematic. Consequently, there is an urgent need for a more precise, rapid and affordable diagnostic test for childhood tuberculosis.
The new so-called TAM-TB assay is a sputum-independent blood test. It makes use of an immunological phenomenon during tuberculosis disease: During an active infection, the expression of CD27 – a surface marker expressed on mycobacteria specific CD4+ T cells – is lost. Using standard intracellular cytokine staining procedures and polychromatic flow cytometry, the test result is available within 24 hours after blood sampling.
New blood test assessed in tuberculosis endemic regions in Tanzania
The new test was assessed in tuberculosis endemic regions in Tanzania at the Ifakara Health Institute and the NIMR Mbeya Medical Research Center. Sputum and blood samples were obtained from children with tuberculosis symptoms to compare the performance of the new assay with culture tests. For the assessment of the diagnostic performance of the new test, the children were assigned to standardized clinical case classifications based on microbiological and clinical findings. The test proved to have a good sensitivity and excellent specificity.
“This rapid and reliable test has the great potential to significantly improve the diagnosis of active tuberculosis in children ” says TB CHILD Program Manager Klaus Reither from the Swiss Tropical and Public Health Institute (Swiss TPH), who coordinated the study.
In a collaborative effort between Swiss TPH and Ludwigs-Maximilians-Universität München (LMU Munich), the test will now be further refined to optimise performance, particularly in HIV-infected children, and to reduce costs. The goal is to finally validate and implement a rapid, robust and accurate diagnostic test for active paediatric tuberculosis that can be used on the district level in resource-poor, tuberculosis-endemic countries.
Swiss Tropical and Public Health Institute
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New research which finds that invisible blood in urine may be an early warning sign of bladder cancer is likely to shape guidelines for clinicians.
Scientists at the University of Exeter Medical School found that one in 60 people over the age of 60 who had invisible blood in their urine (identified by their GP testing their urine) transpired to have bladder cancer.
The figure was around half those who had visible blood in their urine – the best known indicator of bladder cancer. However, it was still higher than figures for other potential symptoms of bladder cancer that warrant further investigation.
Lead author Sarah Price, a PhD student at the University of Exeter Medical School, led the first robust study to investigate whether invisible blood in urine can indicate bladder cancer. She said: “It is well known that if you see blood in your urine you should contact your GP, who is likely to refer you for tests. But there is no clear guidance for GPs on what to do if they detect blood that is not visible during routine tests. We are hopeful that our findings will now lead to robust guidance that it warrants further investigation. Early diagnosis is crucial to have the best chance of successfully treating bladder cancer. The three-quarters of patients who are diagnosed early have much better outcomes than those whose disease is diagnosed late. Anything we can do to boost early detection is crucial to help save lives.”
The study examined more than 26,000 people whose anonymised data contributed to the Clinical Practice Research Datalink; this is a large research database used by the Exeter team in several cancer studies. The team found that the risk of bladder cancer was 1.6 per cent in people over 60 who had invisible blood in their urine.
Around 10,000 people in the UK are diagnosed with bladder cancer each year. The condition is more common in men than women and in older people, with the average age of diagnosis at 68. Smoking is among the main causes.
University of Exeter Medical School
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Two new potential therapeutic targets for the treatment of pulmonary arterial hypertension, a deadly disease marked by high blood pressure in the lungs, have been identified by researchers at the University of Illinois at Chicago.
Early symptoms of pulmonary arterial hypertension include shortness of breath and exercise intolerance. As the disease progresses, patients may require oxygen supplementation and lung transplantation. Heart failure can develop and is a major cause of death in the disease.
Most cases of pulmonary hypertension are of unknown cause, though the condition often occurs in association with other diseases, including scleroderma, congenital heart disease and liver disease. One of the underlying factors driving the increased blood pressure in the lungs is a narrowing of the pulmonary blood vessels. This narrowing can be due to an abnormal proliferation of cells within the walls of the blood vessels, particularly in the smooth muscle cells of the pulmonary artery.
Jiwang Chen, research assistant professor of critical care medicine, sleep and allergy in the UIC College of Medicine, and his colleagues investigated the molecular mechanisms behind the abnormal proliferation of smooth muscle cells in the pulmonary artery and discovered two ways that the proliferation could be suppressed.
They knew that an enzyme, sphingosine kinase 1, that produces a signalling molecule called sphingosine-1-phosphate (S1P), had been linked to the abnormal growth of cells in cancer, including lung cancer.
“The characteristic proliferation of cells that line the blood vessels in pulmonary hypertension is similar to the abnormal growth and reproduction of cells that form cancerous tumours,” says Chen. “We wanted to see if sphingosine kinase 1 and S1P were involved in the development of pulmonary arterial hypertension.”
Looking at samples of lung tissue from patients, Chen and colleagues found that patients with pulmonary arterial hypertension had significantly elevated levels of both the enzyme and the signalling molecule it produces. They found similarly elevated levels of both molecules in mouse and rat models of pulmonary hypertension.
Knockout mice lacking the gene for sphingosine kinase 1 were less likely than normal mice to develop pulmonary hypertension when exposed to the low-oxygen conditions used to induce the disease in the laboratory.
Drugs that either suppress production of sphingosine kinase 1 or block the signalling of S1P through its receptors on smooth muscle cells prevented mice from developing pulmonary hypertension in low-oxygen conditions.
The researchers also showed in mice that over-production of sphingosine kinase 1 and S1P promote the proliferation of pulmonary artery smooth muscle cells.
“Our results yield two new potential targets for the development of drugs to treat or prevent the progression of pulmonary arterial hypertension,” Chen said.
“By blocking the binding site for S1P or suppressing the production of S1P, like we did in our experimental rodent model, we can reduce the proliferation of pulmonary artery smooth muscle cells, which is a major contributor to pulmonary hypertension.”
University of Illinois at Chicago
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A genetic mutation caused by ultraviolet light is likely the driving force behind millions of human skin cancers, according to researchers at the Stanford University School of Medicine.
The mutation occurs in a gene called KNSTRN, which is involved in helping cells divide their DNA equally during cell division.
Genes that cause cancer when mutated are known as oncogenes. Although KNSTRN hasn’t been previously implicated as a cause of human cancers, the research suggests it may be one of the most commonly mutated oncogenes in the world.
“This previously unknown oncogene is activated by sunlight and drives the development of cutaneous squamous cell carcinomas,” said Paul Khavari, MD, PhD, the Carl J. Herzog Professor in Dermatology in the School of Medicine and chair of the Department of Dermatology. “Our research shows that skin cancers arise differently from other cancers, and that a single mutation can cause genomic catastrophe.”
Cutaneous squamous cell carcinoma is the second most common cancer in humans. More than 1 million new cases are diagnosed globally each year. The researchers found that a particular region of KNSTRN is mutated in about 20 percent of cutaneous squamous cell carcinomas and in about 5 percent of melanomas.
Lee and Khavari made the discovery while investigating the genetic causes of cutaneous squamous cell carcinoma. They compared the DNA sequences of genes from the tumour cells with those of normal skin and looked for mutations that occurred only in the tumours. They found 336 candidate genes for further study, including some familiar culprits. The top two most commonly mutated genes were CDKN2A and TP53, which were already known to be associated with squamous cell carcinoma.
The third most commonly mutated gene, KNSTRN, was a surprise. It encodes a protein that helps to form the kinetochore — a structure that serves as a kind of handle used to pull pairs of newly replicated chromosomes to either end of the cell during cell division. Sequestering the DNA at either end of the cell allows the cell to split along the middle to form two daughter cells, each with the proper complement of chromosomes.
If the chromosomes don’t separate correctly, the daughter cells will have abnormal amounts of DNA. These cells with extra or missing chromosomes are known as aneuploid, and they are often severely dysfunctional. They tend to misread cellular cues and to behave erratically. Aneuploidy is a critical early step toward the development of many types of cancer.
The mutation in the KNSTRN gene was caused by the replacement of a single nucleotide, called a cytosine, with another, called a thymine, within a specific, short stretch of DNA. The swap is indicative of a cell’s attempt to repair damage from high-energy ultraviolet rays, such as those found in sunlight.
“Mutations at this UV hotspot are not found in any of the other cancers we investigated,” said Khavari. “They occur only in skin cancers.”
The researchers found the UV-induced KNSTRN mutation in about 20 percent of actinic keratoses — a premalignant skin condition that often progresses to squamous cell carcinoma — but never in 122 samples of normal skin, indicating the mutation is likely to be an early event in the development of squamous cell carcinomas.
Furthermore, overexpression of mutant KNSTRN in laboratory-grown human skin cells disrupted their ability to segregate their DNA during cell division and enhanced the growth of cancer cells in a mouse model of squamous cell carcinoma.
Finally, Lee compared five patient-derived squamous cell carcinomas that had the KNSTRN mutation with five samples that did not have the mutation. Although both sets of cells were aneuploid, those with the mutation had the most severely abnormal genomes.
Stanford University School of Medicine
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Researchers from Oregon State Public Health Lab have modified the protocol for a relatively new test for a dangerous form of antibiotic resistance, increasing its specificity to 100 percent. Their research, confirming the reliability of a test that can provide results in hours and is simple and inexpensive enough to be conducted in practically any clinical laboratory.
The test, called Carba NP, originally developed by Patrice Nordmann and Laurent Poirel at the University of Fribourg, Switzerland, and Laurent Dortet of the University Hospital of the South-Paris Medical School, France, allows for rapid identification of carbapenem-resistant Enterobacteriaceae (CRE), often referred to in the media as ‘super bugs’ for their ability to resist most major antibiotics. Carbapenems are an important class of powerful antibiotics for treating severe infections caused by multidrug-resistant Gram negative bacteria. Carbapenemases are enzymes produced by some bacteria which inactivate these antibiotics.
‘Over the past decade carbapenemase-producing CRE (CP-CRE) have rapidly spread around the globe and are currently considered an urgent public health threat by the Centers for Disease Control and Prevention (CDC),’ says Karim Morey of the Oregon State Public Health Lab, an author on the study. ‘Timely detection of CP-CRE is critical to patient care and infection control.’
Polymerase chain reaction (PCR), a DNA-based test, is currently the gold standard for detecting CRE, but it is expensive and requires equipment that many labs just do not have, especially in low-income countries that are large reservoirs for CRE. Carba NP is a much less expensive test that most labs should be able to afford.
In the study Morey and her colleagues evaluated the ability of the Carba NP test to properly identify 59 of the 201 clinical isolates as carbapenemase producers. Using a previously published Mayo Clinic protocol, they correctly identified 92% as being carbapenemase producers, including all strains of NDM-1 and KPC, two important types of CRE. When they adjusted the protocol to increase the inoculum size and tested again they achieved 100% sensitivity. The average time to complete a test was 2.5 hours.
‘We conclude that the Carba NP test is highly sensitive, specific and reproducible for the detection of carbapenemase production in a diverse group of organisms,’ says Morey.
This work was done as part of the Drug Resistant Organism Coordinated Regional Epidemiology Network, a statewide initiative to prevent the emergence and spread of CRE in the state of Oregon and Funded by the CDC.
EurekAlert
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Researchers at UT Southwestern Medical Center and the Gill Center for Cancer and Blood Disorders at Children’s Medical Center, Dallas, have made significant progress in defining new genetic causes of Wilms tumor, a type of kidney cancer found only in children.
Wilms tumour is the most common childhood genitourinary tract cancer and the third most common solid tumour of childhood.
“While most children with Wilms tumour are thankfully cured, those with more aggressive tumours do poorly, and we are increasingly concerned about the long-term adverse side effects of chemotherapy in Wilms tumour patients. We wanted to know – what are the genetic causes of Wilms tumour in children and what are the opportunities for targeted therapies? To answer these questions, you have to identify genes that are mutated in the cancer,” said Dr. James Amatruda, Associate Professor of Pediatrics, Molecular Biology, and Internal Medicine at UT Southwestern and senior author for the study.
Collaborating with Dr. Amatruda on the study were UT Southwestern faculty members Dr. Dinesh Rakheja, Associate Professor of Pathology and Pediatrics; Dr. Kenneth S. Chen, Assistant Instructor in Pediatrics; and Dr. Joshua T. Mendell, Professor of Molecular Biology. Dr. Jonathan Wickiser, Associate Professor in Pediatrics, and Dr. James Malter, Chair of Pathology, are also co-authors.
Previous research has identified one or two mutant genes in Wilms tumours, but only about one-third of Wilms tumors had these mutations.
“We wanted to know what genes were mutated in the other two-thirds. To accomplish this goal, we sequenced the DNA of 44 tumours and identified several new mutated genes,” said Dr. Amatruda, who holds the Nearburg Family Professorship in Pediatric Oncology Research and is an Attending Physician in the Pauline Allen Gill Center for Cancer and Blood Disorders at Children’s Medical Center. “The new genes had not been identified before. The most common, and in some ways the most biologically interesting, mutations were found in genes called DROSHA and DICER1. We found that these mutations affected the cell’s production of microRNAs, which are tiny RNA molecules that play big roles in controlling the growth of cells, and the primary effect was on a family of microRNAs called let-7.”
“Let-7 is an important microRNA that slows cell growth and in Wilms tumours in which DROSHA or DICER1 were mutated, let-7 RNA is missing, which causes the cells to grow abnormally fast,” Dr. Amatruda said.
These findings have implications for future treatment of Wilms tumour and several other childhood cancers, including neuroblastoma, germ cell tumour, and rhabdomyosarcoma.
“What’s exciting about these results is that we can begin to understand what drives the growth of different types of Wilms tumours. This is a critical first step in trying to treat the cancer based on its true molecular defect, rather than just what a tumour looks like under a microscope,” Dr. Amatruda said. “Most importantly, we begin to think in concrete terms about a therapy, which is an exciting translational goal of our work in the next few years.
UT Southwestern Medical Center
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Faster, cheaper tests for sickle cell
, /in E-News /by 3wmediaNewly developed test can identify sickle cell disease in minutes and could be used in rural clinics around the globe
Within minutes after birth, every child in the U.S. undergoes a battery of tests designed to diagnose a host of conditions, including sickle cell disease. Thousands of children born in the developing world, however, aren’t so lucky, meaning many suffer and die from the disease each year.
A.J. Kumar hopes to put a halt to at least some of those deaths.
A Post-Doctoral Fellow in Chemistry and Chemical Biology working in the lab of George Whitesides, the Woodford L. and Ann A. Flowers University Professor, Kumar and colleagues, including other co-authors, have developed a new test for sickle cell disease that provides results in just 12 minutes and costs as little as 50 cents – far faster and cheaper than other tests.
‘The tests we have today work great, they have a very high sensitivity,’ Kumar said. ‘But the equipment needed to run them costs in the tens of thousands of dollars, and they take hours to run. That’s not amenable to rural clinics, or even some cities where the medical infrastructure isn’t up to the standards we see in the U.S. That’s where having a rapid, low-cost test becomes important and this paper shows such a test can potentially work.’
When run against more than 50 clinical samples – 26 positive and 26 negative – the new test showed good sensitivity and specificity for the disease, Kumar said, so the early evidence is promising, but additional testing will be needed to determine whether the test is truly accurate enough to use in the field.
The test designed by Kumar is deceptively simple, and works by connecting two ideas scientists have understood for decades.
The first is the notion that blood cells affected by the disease are denser than normal cells, and the second is that many polymers, when mixed in water, automatically separate into layers ordered by density.
Conventional methods to separate cells by density relied on layering liquids with different density by hand. The insight, arrived at by Charles Mace (now at Tufts) and Kumar, was that the self-forming layers could be used to separate cells, such as red blood cells, by density.
‘When you mix the polymers with water, they separate just like oil and water,’ he said. ‘Even if you mix it up, it will still come back to those layers.’
It wasn’t until a chance meeting with Dr. Thomas Stossel, however, that Kumar believed the technology might have a real impact on sickle cell disease.
‘Initially, we started off working on malaria, because we thought when parasites invaded the cells, it would change their density,’ he said. ‘But when I met Tom Stossel on a panel at the Harvard Medical School, he said, ‘You need to work on sickle cell.’ He’s a haematologist by training and has been working with a non-profit in Zambia for the past decade, so he’s seen the need and the lack of a diagnostic tool.’
When Kumar and colleagues ran tests with infected blood, their results were unmistakable. While healthy red blood cells settled in the tubes at specific levels, the dense cells from blood infected with sickle cell settled in a band significantly lower. The band of red cells could clearly be seen by eye.
Just showing that the test worked, however, wasn’t enough.
‘We wanted to make the test as simple as possible,’ Kumar explained. ‘The idea was to make it something you could run from just a finger prick. Because these gradients assemble on their own, that meant we could make them in whatever volume we wanted, even a small capillary tube.’
The design the team eventually settled on is barely larger than a toothpick. In the field, Kumar said, running the test is as simple as uncapping the tube, pricking a patient’s finger and allowing the blood to wick into the tube.
While further study is needed to determine how accurate and effective the test may be, Kumar said stopping even a few sickle-cell-related deaths would EurekAlert
Research offers insight into cellular biology of colorectal cancer
, /in E-News /by 3wmediaA study by researchers at the University of Kansas shows a new role for the protein adenomatous polyposis coli (APC) in suppressing colorectal cancer — the second-leading cause of cancer-related deaths in the U.S.
Lead author Kristi Neufeld, associate professor in the Department of Molecular Biosciences and co-leader of the Cancer Biology program at the KU Cancer Center, has spent the better part of her career trying to understand the various activities of APC, a protein whose functional loss is thought to initiate roughly 80 percent of all colon polyps, a precursor to colon cancer. Neufeld, along with her postdoctoral fellow Maged Zeineldin, undergraduate student Mathew Miller and veterinary pathologist Ruth Sullivan, now reports that APC found in a particular subcellular compartment, the nucleus, protects from inflammation as well as tumour development associated with chronic colitis.
Whether APC reaches the nucleus may well affect the ability of intestinal stem cells to produce differentiated cells with specialized functions, Neufeld said.
“It’s not widely appreciated, but there is still plenty of cell growth going on in adults, with the colon being a good example,” she said. “On average, we shed and replace about 70 pounds of intestinal tissue annually, so you can imagine that this process requires exquisite control to prevent tumour formation.”
Regular renewal of the colon lining occurs through stem cells that are capable of constantly dividing. These cells produce descendants that take up specific roles: By secreting mucin, for instance, goblet cells generate a mucus layer that serves as the colon’s physical barrier against its many microbial tenants. But if APC can’t find its way to the nucleus, Neufeld and her team have noted far fewer goblet cells as one outcome.
“We introduced a specific APC mutation into mice that took away the nuclear zip code, so to speak, leaving APC stuck in the cytoplasm,” Neufeld said. The researchers studied this mouse model under conditions that induce ulcerative colitis, a form of inflammatory bowel disease that can be a prelude to colon cancer.
Observing significantly more colon tumours in these mice compared to those with normal APC in the same disease setting, they hypothesized that functional nuclear APC might somehow guard against inflammation and its downstream effects, including tumour development. Now, Neufeld thinks she and her team may have a clue as to how this happens.
“The drop in goblet cell numbers we observed was striking,” she said. “We then examined one of the proteins found in mucus, called Muc2, and found that its RNA levels were greatly decreased. If there are fewer goblet cells as a result of APC being unable to reach the nucleus, there will also be less mucus, which could increase the colon’s sensitivity to bacteria and other microorganisms in the gut that are capable of promoting inflammation.”
Neufeld said while there are still no quick fixes for mutant genes, perhaps tools could be developed to synthetically replace this less-than-ideally thick mucus layer in affected people.
One known function of APC is that it halts cell proliferation: by muzzling the canonical arm of the Wnt signaling pathway, which otherwise instructs cells to go forth and multiply. Neufeld and her group have already shown, using the same mouse model, that APC stationed in the nucleus is necessary to suppress Wnt and its signaling partners — particularly β-catenin, a key target of normal APC. With a role for nuclear APC in controlling goblet cell differentiation now supported, the researchers are probing possible mechanisms to learn if and how Wnt pathway members might be involved. Kansas University
Test reliably detects inherited immune deficiency in newborns
, /in E-News /by 3wmediaA newborn screening test for severe combined immunodeficiency (SCID) reliably identifies infants with this life-threatening inherited condition, leading to prompt treatment and high survival rates, according to a study supported by the National Institutes of Health. Researchers led by Jennifer Puck, M.D., of the University of California, San Francisco, also found that SCID affects approximately 1 in 58,000 newborns, indicating that the disorder is less rare than previously thought. The study was funded in part by NIH’s National Institute of Allergy and Infectious Diseases (NIAID) and Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).
SCID is a group of disorders caused by defects in genes involved in the development and function of T cells and other infection-fighting immune cells. Infants with SCID are highly susceptible to life-threatening infections. SCID is fatal, usually within the first year or two of life, unless affected infants are given immune-restoring treatments such as transplants of blood-forming stem cells or gene therapy. More than 80 percent of affected infants do not have a family history of the condition.
“The results of this study highlight the important role of newborn screening for SCID,” said NIAID Director Anthony S. Fauci, M.D. “The findings demonstrate that detecting SCID before symptoms such as severe infections appear helps ensure that infants with this serious condition receive lifesaving treatments.”
The SCID newborn screening test, originally developed at NIH, measures T cell receptor excision circles (TRECs), a by-product of T-cell development. Infants with SCID have few or no T cells, regardless of the underlying genetic defect, and the absence of TRECs may indicate SCID. The TREC test also may help doctors identify infants with non-SCID T-cell deficiencies. SCID was added in 2010 to the U.S. Department of Health and Human Services’ Recommended Uniform Screening Panel for newborns in the United States. However, the TREC test has not yet been adopted universally. Nearly half of states conduct newborn screening for SCID, and the test is performed for almost two thirds of infants born across the country.
“We have made great strides in our knowledge of SCID and other related immunodeficiencies in a relatively short period of time, thanks to newborn screening,” said Tiina Urv, Ph.D., a program director in the Intellectual and Developmental Disabilities Branch at NICHD. “Such collaborative research efforts could serve as a model for other disorders.” Eunice Kennedy Shriver National Institute of Child Health and Human Development
A new way to diagnose malaria
, /in E-News /by 3wmediaOver the past several decades, malaria diagnosis has changed very little. After taking a blood sample from a patient, a technician smears the blood across a glass slide, stains it with a special dye, and looks under a microscope for the Plasmodium parasite, which causes the disease. This approach gives an accurate count of how many parasites are in the blood — an important measure of disease severity — but is not ideal because there is potential for human error.
A research team from the Singapore-MIT Alliance for Research and Technology (SMART) has now come up with a possible alternative. The researchers have devised a way to use magnetic resonance relaxometry (MRR), a close cousin of magnetic resonance imaging (MRI), to detect a parasitic waste product in the blood of infected patients. This technique could offer a more reliable way to detect malaria, says Jongyoon Han, a professor of electrical engineering and biological engineering at MIT.
“There is real potential to make this into a field-deployable system, especially since you don’t need any kind of labels or dye. It’s based on a naturally occurring biomarker that does not require any biochemical processing of samples” says Han, one of the senior authors of a paper describing the technique.
With the traditional blood-smear technique, a technician stains the blood with a reagent that dyes cell nuclei. Red blood cells don’t have nuclei, so any that show up are presumed to belong to parasite cells. However, the technology and expertise needed to identify the parasite are not always available in some of the regions most affected by malaria, and technicians don’t always agree in their interpretations of the smears, Han says.
“There’s a lot of human-to-human variation regarding what counts as infected red blood cells versus some dust particles stuck on the plate. It really takes a lot of practice,” he says.
The new SMART system detects a parasitic waste product called haemozoin. When the parasites infect red blood cells, they feed on the nutrient-rich haemoglobin carried by the cells. As haemoglobin breaks down, it releases iron, which can be toxic, so the parasite converts the iron into hemozoin — a weakly paramagnetic crystallite.
Those crystals interfere with the normal magnetic spins of hydrogen atoms. When exposed to a powerful magnetic field, hydrogen atoms align their spins in the same direction. When a second, smaller field perturbs the atoms, they should all change their spins in synchrony — but if another magnetic particle, such as hemozoin, is present, this synchrony is disrupted through a process called relaxation. The more magnetic particles are present, the more quickly the synchrony is disrupted.
“What we are trying to really measure is how the hydrogen’s nuclear magnetic resonance is affected by the proximity of other magnetic particles,” Han says.
For this study, the researchers used a 0.5-tesla magnet, much less expensive and powerful than the 2- or 3-tesla magnets typically required for MRI diagnostic imaging, which can cost up to $2 million. The current device prototype is small enough to sit on a table or lab bench, but the team is also working on a portable version that is about the size of a small electronic tablet.
After taking a blood sample and spinning it down to concentrate the red blood cells, the sample analysis takes less than a minute. Only about 10 microliters of blood is required, which can be obtained with a finger prick, making the procedure minimally invasive and much easier for health care workers than drawing blood intravenously.
“This system can be built at a very low cost, relative to the million-dollar MRI machines used in a hospital,” Peng says. “Furthermore, since this technique does not rely on expensive labelling with chemical reagents, we are able to get each diagnostic test done at a cost of less than 10 cents.” MIT
New tuberculosis blood test in children is reliable and highly specific
, /in E-News /by 3wmediaA new blood test provides a fast and accurate tool to diagnose tuberculosis in children, a new proof-of-concept study shows. The newly developed test (TAM-TB assay) is the first reliable immunodiagnostic assay to detect active tuberculosis in children. The test features excellent specificity, a similar sensitivity as culture tests in combination with speed of a blood test. The promising findings are a major advance for the diagnosis of tuberculosis in children, particularly in tuberculosis-endemic regions.
Tuberculosis (TB) in children is a serious public health problem especially in low-resource countries. About one million children per year develop tuberculosis worldwide. Unfortunately, the diagnosis of paediatric TB poses a major challenge. TB symptoms in children are often non-specific and similar to those of common paediatric illnesses, including pneumonia and malnutrition. Further, obtaining adequate respiratory specimens for direct mycobacterial confirmation is problematic. Consequently, there is an urgent need for a more precise, rapid and affordable diagnostic test for childhood tuberculosis.
The new so-called TAM-TB assay is a sputum-independent blood test. It makes use of an immunological phenomenon during tuberculosis disease: During an active infection, the expression of CD27 – a surface marker expressed on mycobacteria specific CD4+ T cells – is lost. Using standard intracellular cytokine staining procedures and polychromatic flow cytometry, the test result is available within 24 hours after blood sampling.
New blood test assessed in tuberculosis endemic regions in Tanzania
The new test was assessed in tuberculosis endemic regions in Tanzania at the Ifakara Health Institute and the NIMR Mbeya Medical Research Center. Sputum and blood samples were obtained from children with tuberculosis symptoms to compare the performance of the new assay with culture tests. For the assessment of the diagnostic performance of the new test, the children were assigned to standardized clinical case classifications based on microbiological and clinical findings. The test proved to have a good sensitivity and excellent specificity.
“This rapid and reliable test has the great potential to significantly improve the diagnosis of active tuberculosis in children ” says TB CHILD Program Manager Klaus Reither from the Swiss Tropical and Public Health Institute (Swiss TPH), who coordinated the study.
In a collaborative effort between Swiss TPH and Ludwigs-Maximilians-Universität München (LMU Munich), the test will now be further refined to optimise performance, particularly in HIV-infected children, and to reduce costs. The goal is to finally validate and implement a rapid, robust and accurate diagnostic test for active paediatric tuberculosis that can be used on the district level in resource-poor, tuberculosis-endemic countries. Swiss Tropical and Public Health Institute
Invisible blood in urine may indicate bladder cancer
, /in E-News /by 3wmediaNew research which finds that invisible blood in urine may be an early warning sign of bladder cancer is likely to shape guidelines for clinicians.
Scientists at the University of Exeter Medical School found that one in 60 people over the age of 60 who had invisible blood in their urine (identified by their GP testing their urine) transpired to have bladder cancer.
The figure was around half those who had visible blood in their urine – the best known indicator of bladder cancer. However, it was still higher than figures for other potential symptoms of bladder cancer that warrant further investigation.
Lead author Sarah Price, a PhD student at the University of Exeter Medical School, led the first robust study to investigate whether invisible blood in urine can indicate bladder cancer. She said: “It is well known that if you see blood in your urine you should contact your GP, who is likely to refer you for tests. But there is no clear guidance for GPs on what to do if they detect blood that is not visible during routine tests. We are hopeful that our findings will now lead to robust guidance that it warrants further investigation. Early diagnosis is crucial to have the best chance of successfully treating bladder cancer. The three-quarters of patients who are diagnosed early have much better outcomes than those whose disease is diagnosed late. Anything we can do to boost early detection is crucial to help save lives.”
The study examined more than 26,000 people whose anonymised data contributed to the Clinical Practice Research Datalink; this is a large research database used by the Exeter team in several cancer studies. The team found that the risk of bladder cancer was 1.6 per cent in people over 60 who had invisible blood in their urine.
Around 10,000 people in the UK are diagnosed with bladder cancer each year. The condition is more common in men than women and in older people, with the average age of diagnosis at 68. Smoking is among the main causes. University of Exeter Medical School
New targets for treating pulmonary hypertension found
, /in E-News /by 3wmediaTwo new potential therapeutic targets for the treatment of pulmonary arterial hypertension, a deadly disease marked by high blood pressure in the lungs, have been identified by researchers at the University of Illinois at Chicago.
Early symptoms of pulmonary arterial hypertension include shortness of breath and exercise intolerance. As the disease progresses, patients may require oxygen supplementation and lung transplantation. Heart failure can develop and is a major cause of death in the disease.
Most cases of pulmonary hypertension are of unknown cause, though the condition often occurs in association with other diseases, including scleroderma, congenital heart disease and liver disease. One of the underlying factors driving the increased blood pressure in the lungs is a narrowing of the pulmonary blood vessels. This narrowing can be due to an abnormal proliferation of cells within the walls of the blood vessels, particularly in the smooth muscle cells of the pulmonary artery.
Jiwang Chen, research assistant professor of critical care medicine, sleep and allergy in the UIC College of Medicine, and his colleagues investigated the molecular mechanisms behind the abnormal proliferation of smooth muscle cells in the pulmonary artery and discovered two ways that the proliferation could be suppressed.
They knew that an enzyme, sphingosine kinase 1, that produces a signalling molecule called sphingosine-1-phosphate (S1P), had been linked to the abnormal growth of cells in cancer, including lung cancer.
“The characteristic proliferation of cells that line the blood vessels in pulmonary hypertension is similar to the abnormal growth and reproduction of cells that form cancerous tumours,” says Chen. “We wanted to see if sphingosine kinase 1 and S1P were involved in the development of pulmonary arterial hypertension.”
Looking at samples of lung tissue from patients, Chen and colleagues found that patients with pulmonary arterial hypertension had significantly elevated levels of both the enzyme and the signalling molecule it produces. They found similarly elevated levels of both molecules in mouse and rat models of pulmonary hypertension.
Knockout mice lacking the gene for sphingosine kinase 1 were less likely than normal mice to develop pulmonary hypertension when exposed to the low-oxygen conditions used to induce the disease in the laboratory.
Drugs that either suppress production of sphingosine kinase 1 or block the signalling of S1P through its receptors on smooth muscle cells prevented mice from developing pulmonary hypertension in low-oxygen conditions.
The researchers also showed in mice that over-production of sphingosine kinase 1 and S1P promote the proliferation of pulmonary artery smooth muscle cells.
“Our results yield two new potential targets for the development of drugs to treat or prevent the progression of pulmonary arterial hypertension,” Chen said.
“By blocking the binding site for S1P or suppressing the production of S1P, like we did in our experimental rodent model, we can reduce the proliferation of pulmonary artery smooth muscle cells, which is a major contributor to pulmonary hypertension.” University of Illinois at Chicago
UV light can turn gene into source of skin cancers, researchers find
, /in E-News /by 3wmediaA genetic mutation caused by ultraviolet light is likely the driving force behind millions of human skin cancers, according to researchers at the Stanford University School of Medicine.
The mutation occurs in a gene called KNSTRN, which is involved in helping cells divide their DNA equally during cell division.
Genes that cause cancer when mutated are known as oncogenes. Although KNSTRN hasn’t been previously implicated as a cause of human cancers, the research suggests it may be one of the most commonly mutated oncogenes in the world.
“This previously unknown oncogene is activated by sunlight and drives the development of cutaneous squamous cell carcinomas,” said Paul Khavari, MD, PhD, the Carl J. Herzog Professor in Dermatology in the School of Medicine and chair of the Department of Dermatology. “Our research shows that skin cancers arise differently from other cancers, and that a single mutation can cause genomic catastrophe.”
Cutaneous squamous cell carcinoma is the second most common cancer in humans. More than 1 million new cases are diagnosed globally each year. The researchers found that a particular region of KNSTRN is mutated in about 20 percent of cutaneous squamous cell carcinomas and in about 5 percent of melanomas.
Lee and Khavari made the discovery while investigating the genetic causes of cutaneous squamous cell carcinoma. They compared the DNA sequences of genes from the tumour cells with those of normal skin and looked for mutations that occurred only in the tumours. They found 336 candidate genes for further study, including some familiar culprits. The top two most commonly mutated genes were CDKN2A and TP53, which were already known to be associated with squamous cell carcinoma.
The third most commonly mutated gene, KNSTRN, was a surprise. It encodes a protein that helps to form the kinetochore — a structure that serves as a kind of handle used to pull pairs of newly replicated chromosomes to either end of the cell during cell division. Sequestering the DNA at either end of the cell allows the cell to split along the middle to form two daughter cells, each with the proper complement of chromosomes.
If the chromosomes don’t separate correctly, the daughter cells will have abnormal amounts of DNA. These cells with extra or missing chromosomes are known as aneuploid, and they are often severely dysfunctional. They tend to misread cellular cues and to behave erratically. Aneuploidy is a critical early step toward the development of many types of cancer.
The mutation in the KNSTRN gene was caused by the replacement of a single nucleotide, called a cytosine, with another, called a thymine, within a specific, short stretch of DNA. The swap is indicative of a cell’s attempt to repair damage from high-energy ultraviolet rays, such as those found in sunlight.
“Mutations at this UV hotspot are not found in any of the other cancers we investigated,” said Khavari. “They occur only in skin cancers.”
The researchers found the UV-induced KNSTRN mutation in about 20 percent of actinic keratoses — a premalignant skin condition that often progresses to squamous cell carcinoma — but never in 122 samples of normal skin, indicating the mutation is likely to be an early event in the development of squamous cell carcinomas.
Furthermore, overexpression of mutant KNSTRN in laboratory-grown human skin cells disrupted their ability to segregate their DNA during cell division and enhanced the growth of cancer cells in a mouse model of squamous cell carcinoma.
Finally, Lee compared five patient-derived squamous cell carcinomas that had the KNSTRN mutation with five samples that did not have the mutation. Although both sets of cells were aneuploid, those with the mutation had the most severely abnormal genomes. Stanford University School of Medicine
Inexpensive lab test identifies resistant infections in hours
, /in E-News /by 3wmediaResearchers from Oregon State Public Health Lab have modified the protocol for a relatively new test for a dangerous form of antibiotic resistance, increasing its specificity to 100 percent. Their research, confirming the reliability of a test that can provide results in hours and is simple and inexpensive enough to be conducted in practically any clinical laboratory.
The test, called Carba NP, originally developed by Patrice Nordmann and Laurent Poirel at the University of Fribourg, Switzerland, and Laurent Dortet of the University Hospital of the South-Paris Medical School, France, allows for rapid identification of carbapenem-resistant Enterobacteriaceae (CRE), often referred to in the media as ‘super bugs’ for their ability to resist most major antibiotics. Carbapenems are an important class of powerful antibiotics for treating severe infections caused by multidrug-resistant Gram negative bacteria. Carbapenemases are enzymes produced by some bacteria which inactivate these antibiotics.
‘Over the past decade carbapenemase-producing CRE (CP-CRE) have rapidly spread around the globe and are currently considered an urgent public health threat by the Centers for Disease Control and Prevention (CDC),’ says Karim Morey of the Oregon State Public Health Lab, an author on the study. ‘Timely detection of CP-CRE is critical to patient care and infection control.’
Polymerase chain reaction (PCR), a DNA-based test, is currently the gold standard for detecting CRE, but it is expensive and requires equipment that many labs just do not have, especially in low-income countries that are large reservoirs for CRE. Carba NP is a much less expensive test that most labs should be able to afford.
In the study Morey and her colleagues evaluated the ability of the Carba NP test to properly identify 59 of the 201 clinical isolates as carbapenemase producers. Using a previously published Mayo Clinic protocol, they correctly identified 92% as being carbapenemase producers, including all strains of NDM-1 and KPC, two important types of CRE. When they adjusted the protocol to increase the inoculum size and tested again they achieved 100% sensitivity. The average time to complete a test was 2.5 hours.
‘We conclude that the Carba NP test is highly sensitive, specific and reproducible for the detection of carbapenemase production in a diverse group of organisms,’ says Morey.
This work was done as part of the Drug Resistant Organism Coordinated Regional Epidemiology Network, a statewide initiative to prevent the emergence and spread of CRE in the state of Oregon and Funded by the CDC. EurekAlert
Researchers find new gene mutations for Wilms Tumour
, /in E-News /by 3wmediaResearchers at UT Southwestern Medical Center and the Gill Center for Cancer and Blood Disorders at Children’s Medical Center, Dallas, have made significant progress in defining new genetic causes of Wilms tumor, a type of kidney cancer found only in children.
Wilms tumour is the most common childhood genitourinary tract cancer and the third most common solid tumour of childhood.
“While most children with Wilms tumour are thankfully cured, those with more aggressive tumours do poorly, and we are increasingly concerned about the long-term adverse side effects of chemotherapy in Wilms tumour patients. We wanted to know – what are the genetic causes of Wilms tumour in children and what are the opportunities for targeted therapies? To answer these questions, you have to identify genes that are mutated in the cancer,” said Dr. James Amatruda, Associate Professor of Pediatrics, Molecular Biology, and Internal Medicine at UT Southwestern and senior author for the study.
Collaborating with Dr. Amatruda on the study were UT Southwestern faculty members Dr. Dinesh Rakheja, Associate Professor of Pathology and Pediatrics; Dr. Kenneth S. Chen, Assistant Instructor in Pediatrics; and Dr. Joshua T. Mendell, Professor of Molecular Biology. Dr. Jonathan Wickiser, Associate Professor in Pediatrics, and Dr. James Malter, Chair of Pathology, are also co-authors.
Previous research has identified one or two mutant genes in Wilms tumours, but only about one-third of Wilms tumors had these mutations.
“We wanted to know what genes were mutated in the other two-thirds. To accomplish this goal, we sequenced the DNA of 44 tumours and identified several new mutated genes,” said Dr. Amatruda, who holds the Nearburg Family Professorship in Pediatric Oncology Research and is an Attending Physician in the Pauline Allen Gill Center for Cancer and Blood Disorders at Children’s Medical Center. “The new genes had not been identified before. The most common, and in some ways the most biologically interesting, mutations were found in genes called DROSHA and DICER1. We found that these mutations affected the cell’s production of microRNAs, which are tiny RNA molecules that play big roles in controlling the growth of cells, and the primary effect was on a family of microRNAs called let-7.”
“Let-7 is an important microRNA that slows cell growth and in Wilms tumours in which DROSHA or DICER1 were mutated, let-7 RNA is missing, which causes the cells to grow abnormally fast,” Dr. Amatruda said.
These findings have implications for future treatment of Wilms tumour and several other childhood cancers, including neuroblastoma, germ cell tumour, and rhabdomyosarcoma.
“What’s exciting about these results is that we can begin to understand what drives the growth of different types of Wilms tumours. This is a critical first step in trying to treat the cancer based on its true molecular defect, rather than just what a tumour looks like under a microscope,” Dr. Amatruda said. “Most importantly, we begin to think in concrete terms about a therapy, which is an exciting translational goal of our work in the next few years. UT Southwestern Medical Center