Quick Diagnosis for Early Treatment

Dec. 12, 2014

By Medical Discovery News

Quick Diagnosis for Early Treatment

The time it takes to test for the cause of an infection ranges from minutes to weeks. A new generation of biosensors may change that, as they are being developed to identify the viral, bacterial, or fungal origin of an illness within a few hours, allowing physicians to begin the correct treatment sooner.

Many infections have symptoms that resemble the flu, such as HIV, the fungal infection coccidioidomycosis, Ebola, and even anthrax. This makes it very difficult to make a diagnosis. The emergence of new microbial pathogens such as SARS and MERS and bacterial resistance to antibiotics only adds to the fight against infectious agents. Scientists like Louis Pasteur and Robert Koch developed the traditional method for diagnosing infectious disease about 150 years ago, and modern methods have improved their discoveries.

Viruses, bacteria, and fungi have genetic information contained in DNA, RNA, or both. Each strand of DNA or RNA is made of four kinds of building blocks called nucleotides: adenine (A), cytosine (C), guanine (G), and thymine (T) in DNA or uracil (U) in RNA. Every species has a unique genetic code as seen in its arrangement of nucleotides, and by unlocking that code scientists can determine their identity. Each of the nucleotides has a different molecular weight, so the number of each nucleotide in a strand of DNA or RNA can be determined by measuring it on a device called a mass spectrometer. This can identify a microbial pathogen faster than the traditional culturing method, and can also identify those that can’t be grown in a lab.

However, the massive amount of DNA and RNA in a patient’s own cells complicates things. To tackle this problem, inventors of the new biosensor have coupled a mass spectrometer with polymerase chain reaction (PCR) to amplify any piece of genetic information that matches a known sequence from a pathogen. The sensor can then detect a very broad array of potential pathogens simultaneously.

Scientists have been very careful in selecting the unique genetic regions of various pathogens for this test. Once the PCR is used to amplify pieces of potential pathogens in the sample, the mass spectrometer spits out a series of numbers that can be cross-referenced to a database of over 1,000 pathogens that cause human disease in just a few hours.

For example, two children were hospitalized with flu-like symptoms in Southern California in 2009. They tested positive for the flu virus, but doctors did not know which strain of the flu they had. The new sensor analyzed their samples and revealed that both children were infected with H1N1, otherwise known as swine flu, which was not circulating at that time. H1N1 became a pandemic strain with cases all around the world.

This new technology represents a universal pathogen detector, capable of identifying the organism responsible for a person’s illness in just a few hours. Networking the detectors between hospitals and health departments would quickly identify outbreaks and possibly save lives.

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Pancreatic Tumor Marker

May 23, 2014

By Medical Discovery News

Pancreatic Tumor Marker

Pancreatic cancer is the most deadly form of cancer. Each year, 45,000 Americans are diagnosed with it and every year 40,000 people (90 percent) die from it. One reason most people don’t survive pancreatic cancer is most of the pain and symptoms don’t appear until the cancer has progressed and treatment comes too late. Even then, pancreatic cancer is resistant to chemotherapy and radiation. Another reason is that there is not an easy, reliable test for pancreatic cancer – until now.

The pancreas is a small, oblong, flat organ at the back of abdomen between the stomach and the spine. It is responsible for regulating blood sugar levels by producing hormones like insulin. The pancreas also produces enzymes for the digestive system that neutralize stomach acid and help break down carbohydrates, fats, and proteins.

While there aren’t many noticeable symptoms at first, as pancreatic cancer advances it can cause abdominal pain, weight loss, nausea, fatigue, and jaundice, when the skin, eyes, and mucus turn yellow. Since these symptoms are rather generic, even once someone starts experiencing them it is hard to tell the difference between pancreatic cancer and something benign, like gallstones or bile duct stones. While doctors normally use imaging techniques and endoscopies to distinguish between the two, scientists have identified a new marker that can be used to accurately diagnose a pancreatic tumor.

Researchers at the Cleveland Clinic discovered that a protein called vascular endothelial growth factor (VEGF) plays an important role in the formation and growth of cancerous tumors. VEGF resides in bile, a fluid secreted by the liver and stored in the gallbladder that aids the digestion of fats as they move through the digestive system. Therefore, elevated levels of VEGF indicate the presence of cancer.

To detect pancreatic cancer, the team extracted bile from the pancreas and tested its levels of VEGF. Just like with other cancers, high levels of VEGF did mean there was cancer present. This test was accurate 93 percent of the time, and it didn’t confuse cancer with other digestive problems.

So far, these preliminary results show that this test is more accurate than other pancreatic cancer tests currently under development. Earlier this year, a research team from Copenhagen University Hospital discovered that testing patients’ blood for microRNA, pieces of genetic material, in certain patterns could detect pancreatic cancer in its early stages. The only downside is the high rate of false positives. Another blood test looks for the presence of a compound called CA19-9, which is elevated in 80 percent of pancreatic cancer patients.

Furthermore, measuring the amount of VEGF in bile is a relatively inexpensive test. It also suggests that drugs targeting VEGF may be worth experimenting as a way of treating pancreatic cancer.  

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You Are What You Eat

By Medical Discovery News

Feb. 18, 2012

You Are What You Eat

The expression “you are what you eat” motivates some people to eat better. Little could they have known just how true this may be. A new study shows food may be literally changing us from the inside out. Researchers at Nanjing University in China discovered plant microRNA in the blood and tissue of humans and other plant-eating mammals, something no scientist knew was possible.

Surprisingly, some plant genetic material is not broken down by the digestive fluids nor is it killed by boiling water. Chen-Yu Zhang, a molecular biologist who led the Nanjing study, found plant microRNA not merely roaming the blood of human subjects, but changing cellular function. If true, this suggests food has the potential to alter human cells.

MicroRNAs are inside every cell. They’re important in the production of proteins, which do nearly all the work of a cell. They’re one of several types of RNA produced from DNA. MicroRNA and another called messenger RNA, or mRNA, both travel outside the cell nucleus to the cytoplasm. Once there, mRNAs, which carry instructions, are translated by ribosomes into proteins, and microRNAs control how quickly that translation happens.

In all, Zhang and his colleagues found 30 plant microRNAs in the blood of humans and cows. Two in particularly high levels are MIR156a and MIR168a, which are also high in rice, brussel sprouts, broccoli, cabbage and cauliflower. Researchers took the study a step further by testing whether these two plant microRNAs are impacting cellular processes.

For microRNAs to influence the production of proteins, they have to bind to mRNAs. Zhang’s team found that MIR168a had the ability to bind to 50 mammalian mRNAs, in particular one in the liver. In studies with mice, MIR168a bound with a mouse mRNA in the liver to slow its production of a protein that helps remove low density lipoprotein, known as the “bad” cholesterol, from the blood. Could this be the “revenge of the plants”?

The researchers hypothesize that once the plant microRNA is eaten, it’s absorbed by cells lining the stomach wall, then it enters the bloodstream and travels to various organs such as the liver. Since microRNAs are found in every cell scientists have examined, everything people eat could be influencing a myriad of mRNAs inside the body, thereby affecting how cells function.

It’s possible mammalian diets have been influencing physiology and evolution from the beginning. This is not the first evidence of food altering the eater. The green sea slug Elysiachlorotica steals genes for photosynthesis from its favorite snack, green algae. Also, mice fed soybeans have been shown to take up plant’s genetic information. If the Nanjing study can be verified, it could open a whole new field of research on how diet impacts disease.

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