Tuesday, 6 June 2017

Modified Vancomycin: Preventing Antibiotic Resistance in Bacteria

Vancomycin is an antibiotic that is prescribed to treat some potentially serious bacterial infections. For many years, it's been a powerful ally in our fight against disease. In recent times, however, it's lost some of its effectiveness. Bacteria are developing resistance to many of our current antibiotics, including vancomycin. In what could be a very significant discovery, scientists have found a way to modify the vancomycin molecule so that it becomes effective again.

Methicillin-resistant Staphylococcus aureus or MRSA is 
   being absorbed by a white blood cell in this colorized photo.
Vancomycin is used to treat MRSA. (Public domain photo)

The Importance of Antibiotics

Antibiotics are chemicals made by bacteria or fungi in order to attack other organisms. Their discovery was a wonderful time in history. Some very serious and previously fatal diseases were able to be cured by the chemicals. We are currently experiencing the reverse situation, however. As antibiotics stop working due to bacterial resistance, the spectre of untreatable diseases is reappearing.

How Do Bacteria Become Resistant to Antibiotics?

Antibiotic resistance in bacteria develops because of the genetic variability of the individuals in a species. Some individuals in a species of bacteria may contain a gene (or genes) that prevents them from being harmed by a particular antibiotic. When other members of the population are killed by the medication, the resistant ones survive. When they reproduce, they pass on the gene for resistance to some of their offspring. Over time, the population as a whole may become resistant to the antibiotic.

Vancomycin and Its Action

Vancomycin has been prescribed for over sixty years. It was discovered in 1953 in a soil sample from Borneo and is made by a bacterium named Amycolatopsis orientalis. It's prescribed as a treatment for some serious conditions that other antibiotics can no longer cure. Vancomycin may have some major side effects, however. These effects don't always occur, but if they do, they may include hearing and kidney problems.

All forms of vancomycin—natural and modified—work by interfering with the process in which bacteria produce their cell wall. The wall surrounds the cell membrane and has protective functions. Vancomycin does its job by binding to protein fragments (peptides) in the cell wall. Peptides and proteins consist of a chain of amino acids.

Unmodified vancomycin binds to two copies of an amino acid called D-alanine that end some of the peptides in bacterial cell walls. This stops the wall from being assembled and kills the bacteria. Many of the once-susceptible bacteria have now evolved to have a D-alanine paired with a D-lactic acid combination at the end of their peptides instead of a double D-alanine combination, however. Natural vancomycin can't bind with this combination and is therefore rendered ineffective.

Modified Vancomycin

A group of scientists at The Scripps Research Institute in the United States has made modifications to the vancomycin molecule to restore its effectiveness. The first modification was the creation of a form that can bind with with a D-alanine—D-lactic acid pair in a bacterium's cell wall. Other scientists created two additional modifications to the structure of the antibiotic. One prevents the cell wall from being made while the other causes the wall to burst. The Scripps team has now created vancomycin with all three modifications. This means that the altered antibiotic prevents bacteria from making their cell wall in a total of three different ways.

Resistance should be much less likely to develop when the new version of vancomycin is used. If any bacteria become resistant to one of the antibiotic's new abilities, they should be unable to resist the other two, perhaps for a long time into the future.

Animal and human trials are needed before the modified vancomycin can be prescribed by doctors. The information announced so far is both hopeful and exciting, however. We badly need either new antibiotics or old ones that work successfully again. 


A modified antibiotic in the fight against drug resistance from The Guardian newspaper

The creation of a more effective antibiotic from sciencemag.org

Friday, 26 May 2017

Lack of High-Quality Sleep May Contribute to Weight Gain

Getting a good night's sleep (or day's sleep for those with a night job) is important for many reasons. Research suggests that one of these reasons is to prevent or reduce weight gain. Over the last few years, researchers in different institutions have found a link between poor quality sleep and an increase in body weight. Though the exact reason for the link is unknown, several proposals have been made based on the evidence obtained so far. One of the leading theories is that the balance between chemicals that influence appetite and satiety is altered.

Adequate sleep is important.
Public domain photo by claudioscott

Some Possible Reasons for Weight Gain After Sleep Loss

Weight gain after inadequate sleep may be due to one or more factors, including changes in appetite, metabolism, motivation, or the desire for exercise. Researchers at Uppsala University in Sweden recently presented some interesting discoveries at the European Congress of Endocrinology in Lisbon. Some of their discoveries are described in the quote below.

Following sleep loss, normal-weight men prefer larger food portions, seek more calories, exhibit signs of increased food-related impulsivity, experience more pleasure from food, and expend less energy. Christian Benedict, Uppsala University
The researchers made some other interesting discoveries. They found that after sleep loss the level of hormones that promote appetite (such as ghrelin) increased and the level of those that promote satiety (such as glucagon-like peptide 1) decreased. Ghrelin is made by the stomach and glucagon-like peptide 1 is made by the intestine.

The Endocannabinoid System

Like some other scientists who have investigated the effects of sleep loss, the Swedish researchers also found that the level of endocannabinoids that increase appetite rose after lack of sleep. The endocannabinoid system was discovered relatively recently. It seems to be involved in the regulation of a variety of processes, including motivation, reward, and appetite control. It's composed of chemicals that act as signaling molecules and activate the same receptors as delta-9-tetrahydrocannabinol, or THC. THC is also found in marijuana (scientific name Cannabis sativa), which is known to increase appetite.

The Role of Gut Bacteria 

The researchers also claim that sleep loss alters the composition of the bacterial community in our gut. Scientists are discovering that this community seems to have important effects on our lives. Many of these effects are helpful. Some bacteria are harmful, but they are normally kept in check by the good bacteria. If the balance between "good" and "bad" bacteria is altered, we may develop a health problem.

Peer Review

Uppsala University is a respected institution, but at the time of this post their research hadn't yet been peer reviewed. A peer review is performed by researchers who work in the same area as the scientists whose work is being published. The review looks for obvious flaws in the research that make the report unsuitable for publication. Nevertheless, the results of the Swedish research are interesting. Since other scientists have had similar results to some of those made by the Uppsala team, the team's claims may well be accurate.

 A healthy diet as well as adequate sleep is needed to prevent weight gain.
                                               Photo by Linda Crampton

Tips for Getting a Good Night's Sleep 

Sleep experts have some suggestions for helping us rest properly during the night. They say that eating a heavy meal shortly before bed is not a good idea. Neither is drinking caffeine. Some people may need to avoid caffeine in the afternoon as well. Exercise close to bedtime may not be a good idea, either, but this varies in different individuals. Using electronic devices in bed—even small ones like a cell phone—is a bad idea. The light from the device can trick the brain into thinking that it's day time and stop a person from relaxing and falling asleep.

Researchers have pointed out that getting enough high-quality sleep probably won't be very helpful for weight loss if we make lots of poor diet choices or never exercise during the day. Combined with a healthy diet and adequate exercise, it could be very beneficial, however.


Sleep loss and weight gain: Uppsala University research

Lack of sleep and endocannabinoid level: University of Chicago research

Weight gain after insufficient sleep from the Mayo Clinic

Saturday, 20 May 2017

Chili Peppers, the Scoville Heat Scale, and a World Record

Chili peppers or chilis are known for the hot sensation that they produce in the mouth and digestive tract when they're eaten. The heat is produced by a chemical called capsaicin, which has health benefits when used appropriately. The hotness of the pepper is indicated by a number on the Scoville heat scale. Plant breeders have recently created a chili that is said to be so hot and have such a high Scoville number that it may be dangerous, depending on the amount that's eaten. The pepper may have medicinal uses, however.

Photo by Pixel2013, public domain license

Chili Peppers or Chilis

Chili peppers belong to the genus Capsicum, which in turn belongs to the nightshade family, or the Solanaceae. Bell peppers also belong to the genus Capsicum, but unlike their relatives they don't contain capsaicin and aren't hot. Chili and bell peppers contains seeds and are therefore fruits.

Eating chili peppers can irritate the digestive tract, causing a burning sensation—which can sometimes be severe—as well as a flushed face, tears, and sweating. Interestingly, though, researchers have found that although the lining of the digestive tract is temporarily irritated by hot pepper and may feel as though it's on fire, it's not being burned. Nevertheless, the abdominal pain created by the irritation and the nausea and vomiting that may accompany the pain may need medical treatment.

According to the American Chemical Society article referenced below, as someone becomes used to eating hot peppers, they become more tolerant of their effects. A person who is new to eating peppers may experience the most severe effects. It therefore seems like a good idea to start by eating a very small quantity of pepper. It might also be a good idea to have a glass of milk on hand. The casein molecules in milk surround the capsaicin and wash it away.

The Scoville Heat Scale

The Scoville heat scale is named after Wilbur Scoville, a pharmacist who created the scale in 1912. The Scoville rating depends on the capsaicin concentration. Pure capsaicin has a rating of 16 million Scoville Heat Units, or SHU. Bell peppers have a rating of 0 SHU. According to Guinness World Records, the hottest chili pepper at the moment is the Carolina Reaper, which was bred by the PuckerButt Pepper Company in the United States. The full name of the chili is Smokin Ed's Carolina Reaper. The fruit has an average rating of 1,569,300 SHU, but some specimens may have a rating as high as 2 million SHU.

Chili Peppers
Photo by Hans, public domain license

The Dragon's Breath Chili

Information about a new contender for the title of the world's hottest chile pepper has been sent to the Guinness Word Records organization. The Dragon's Breath chili was created as a joint project by a plant breeder in Wales and professors at Nottingham Trent University in the United Kingdom. It reportedly has a rating of 2.48 million SHU. The fruit is orange-red in colour and is about the size of a fingernail.

The new pepper is so hot that eating it might be dangerous as well as painful. The creators have suggested that it could cause anaphylactic shock in some people and block the airways, although this statement is a bit puzzling. Anaphylactic shock is an extreme and very dangerous type of allergic response that affects the whole body, including the airways. Someone would have to be allergic to capsaicin in order to develop this reaction. Still, the pepper has such a high Scoville rating that it might cause harmful effects when eaten. It wasn't created as food, however. The breeders of the chili think that the oil inside it—which contains capsaicin— could be useful as an anesthetic.

Capsaicin in Medicinal Creams

Capsaicin is used in creams to relieve pain from sore muscles and joints. Based on the reports that I've read, it seems to be quite effective for some conditions, including arthritis. It may cause a burning sensation to begin with, but this is often followed by pain relief. The most common explanation for its action is that it reduces the amount of substance P, a neurotransmitter that transmits pain signals. Neurotransmitters control the passage of nerve impulses from one neuron to another. It's interesting that capsaicin has benefits as well as disadvantages. The effects seem to depend on the method of application, the dose, and individual sensitivity to the chemical.


Hot peppers from the American Chemical Society
Capsaicin information from HealthLinkBC (a British Columbia government organization)

Wednesday, 17 May 2017

Mussel Glue Mixture May Significantly Reduce Scarring

A group of researchers in South Korea has just made what could be an important discovery with respect to wound healing. They've used a mixture containing a protein from mussel glue to greatly reduce scarring in rats who experienced a serious skin injury. It's possible that the mixture may be helpful for reducing scarring in humans as well.

Photo by stux, CC0 public domain license

Animal Testing

The experiment that was performed involved creating surface wounds in rats and then observing whether the test mixture reduced scar formation. As with many experiments with lab animals, the treatment of the animals could definitely be criticized. Using stem cells to create different types of human tissue and sections of organs may well reduce the use of animals in medical research in the future. It probably won't persuade researchers to abandon animal research altogether, though, because they sometimes want to look at whole-body effects.

Three classes of medical research are in vivo experiments (done in living things), in vitro experiments (done in lab equipment, and in silico experiments (done with computers or via computer simulations). I'm hoping that the last two types of experiments rapidly become more and more useful.

Collagen in Skin

Collagen is a fibrous protein that could be thought of as the scaffolding for our skin. It forms a network or mesh that helps to support the skin's structure and provide firmness. When we receive a significant wound, the skin that fills in the wound contains parallel strands of collagen in bundles instead of a fibrous network. This is a major contributor to the abnormal appearance of a scar.


Decorin is a protein involved in the normal organization of collagen in the skin. It has been shown to reduce scarring when applied to wounds, but it isn't used therapeutically. It's a complex molecule that is too hard to make and too expensive to use. The Korean researchers used part of the decorin molecule in their experimental mixture, however. They also added a sticky substance from mussels and a collagen-binding molecule to the mixture. The mixture was then applied to the skin of rats with a major wound.

The Rat Experiment

The researchers say that the wounds in some of the animals were treated with the test mixture and then covered with plastic to keep the wound moist. In the other rats in the experiment (which formed the control group), the wound was covered with plastic but nothing else. The wounds on all of the rats had the same width and depth.

The New Scientist article referenced below shows pictures of the rats' wounds over time. Based on these photos, and assuming that there was no further change in skin appearance after day 28, it seems inaccurate to say that the experimental mixture prevented scarring as some headlines do (including the one in the referenced article). The mixture did reduce the size of the scar very significantly, however.

  • By Day 11, 99% of the wounds were closed in the test rats and 78% in the control group.
  • By Day 28, "treated rats had fully recovered" and there was very little scarring. The rats in the control group had thick purple scars.
The scientists found that the collagen in the healed wounds looked normal and that the skin contained oil glands, hair follicles, and blood vessels, structures that are absent from scars. 

Possible Application to Humans

Rats and humans are both mammals, so what applies to one often applies to the other. This isn't always the case, though. The researchers say that one factor which may be significant with respect to the scar experiment is that rats have looser skin than humans and tend to scar less. The scientists plan to experiment on pig skin next, which is more similar to human skin.

Research Reference

Mussel Gloop Can Be Used to Make Wounds Knit from New Scientist

Sunday, 14 May 2017

Sushi and Raw Fish, Parasitic Nematodes, and Anisakiasis

Sushi and sashimi can be delicious, but diners should know that eating a meal of raw fish is potentially dangerous. Unless the fish has been adequately frozen before use, it may harbour a parasitic nematode named Anisakis simplex. The nematode attaches itself to the lining of the gastrointestinal tract (or the digestive tract) and often stays alive for some time. It may cause severe pain as well as other unpleasant and sometimes serious problems.


Nematodes are also known as roundworms. Anisakis is a roundworm with a complex life cycle that involves marine mammals, crustaceans, and fish or squid. The basic steps in the cycle are as follows.
  • The parasite reproduces inside marine mammals such as seals and whales. 
  • The eggs of the parasite are released into the ocean in the animals' feces. 
  • The eggs become larvae, which are eaten by crustaceans.
  • The crustaceans are eaten by fish and squid. The larvae migrate to the muscles of these animals.
  • The fish and squid are eaten by marine mammals. Here the larvae mature and the cycle begins again.
  • If the fish and squid are eaten by humans instead of a marine mammal, a nematode infection may result. 

The parasite can only penetrate the outer layer of the lining of the human digestive tract and eventually dies. This may sound like a good outcome, but the problem is that the presence of the worm triggers a strong response by the immune system. Inflammation occurs and a mass of cells is formed in the tract.

Infection, Symptoms and Treatment

Until quite recently, cases of anisakiasis were generally restricted to countries such as Japan, where raw fish is very popular. In the last few years cases have appeared in other parts of the world as the popularity of raw seafood dishes has spread. The disease can develop after eating fish and squid that is raw and improperly prepared. Sushi and sashimi can both be problematic. Sushi consists of raw fish, vinegared rice, and sometimes additional ingredients such as seaweed or other vegetables. Sashimi consists of thin slices of raw fish.

Possible symptoms of the infection include abdominal pain and swelling, nausea, vomiting, diarrhea (which may be bloody or contain mucus) and a slight fever. Some people experience an allergic reaction when they are infected by the parasite. This reaction may involve a rash and itching. Rarely, anaphylaxis may develop. This is a severe and body-wide allergic response that is life threatening and a medical emergency. As with any symptoms and condition, a doctor is needed in order to diagnose the problem.

The treatment for the disorder is often removal of the parasite by endoscopy or surgery. Endoscopy is a process in which a flexible tube with a tiny camera and a light are inserted into the digestive tract so that a doctor can examine the area. Devices can be inserted into the tube to remove items from the tract if necessary. These items include a nematode attached to the lining of the digestive tract.

How to Kill the Parasite

A professional sushi chef will probably know how to prepare sushi and sashimi safely, at least in North America, where I live. Some communities have a law mandating the correct treatment of the fish. People who prepare the fish at home or without training are more likely to cause a problem.

Adequate cooking will kill parasitic worms. According to the CDC (Centers for Disease Control and Prevention), under specific conditions freezing raw fish will also kill the parasites. The CDC says that one of the following procedures for treating the fish should be used. Note that none of them can be obtained in a home freezer.
  • Freeze at -4 degrees Fahrenheit (-20 degrees Celsius) or below for 7 days.
  • Freeze at -31 degrees Fahrenheit (-35 degrees Celsius) until solid and then store at the same temperature or below for 15 hours.
  • Freeze at -31 degrees Fahrenheit (-35 degrees Celsius) until solid and then store at 4 degrees Fahrenheit (-20 degrees Celsius) or below for 24 hours.
It's important that a raw fish lover checks that their preferred source of sushi or sashimi prepares the food properly. If this is done, it should be possible to enjoy the food and stay safe.

References and Further Information

Information about anisakiasis from the CDC

A case report from the British Medical Journal

Tuesday, 2 May 2017

Soy Protein Might Be Helpful for Inflammatory Bowel Disease

Researchers at Pennsylvania State University have made a discovery that might be helpful for people with inflammatory bowel disease, or IBD. They've found that soy protein reduces inflammation and loss of gut barrier function in mice with an induced condition resembling IBD. The discovery may be applicable to humans as well, although this won't be known for certain until clinical trials are performed.

Soybeans: public domain photo by Jing

Inflammatory Bowel Disease

The word "bowel" is another name for the intestine. Inflammatory bowel disease is the general name for a group of illnesses involving intestinal inflammation. The most common types are Crohn's disease and ulcerative colitis. Crohn's disease most often affects the last part of the small intestine (the ileum) and the large intestine. It may affect other parts of the digestive tract instead or as well, however. Ulcerative colitis usually affects the colon (the first and longest part of the large intestine) and the rectum (the chamber at the end of the colon where stool is stored until it's ready to be released). Both diseases can be painful and seriously interfere with life.

Inflammatory bowel diseases affect nearly 4 million people worldwide and have an economic impact of more than $19 billion annually in the United States. Jeff Mulhollen, Penn State News

Crohn's Disease

The cause of Crohn's disease is unknown. It's thought to be due to a mistake by the immune system, however. Certain bacteria or other environmental factors in the intestine may trigger the immune system to behave abnormally, leading to inflammation. There may be a genetic factor that makes some people more susceptible to the disease than others.

Some possible symptoms of Crohn's disease include stomach pain, severe diarrhea, weight loss, fatigue, and a low-grade fever. In addition, there may be blood in the stool. Anyone with any of these symptoms should consult a doctor. The disease often follows a pattern of flare-up, when symptoms are worse, alternating with remission, when symptoms are milder or absent.

Ulcerative Colitis

Ulcerative colitis is  "ulcerative" because sore or ulcers develop on the intestinal lining. "Colitis" means inflammation of the colon. The condition is believed to be an autoimmune disease. Symptoms of ulcerative colitis often resemble those of Crohn's disease, including the occurrence of flare-ups and remissions. There are a few differences between the two conditions, however.

  • Ulcerative colitis is generally restricted to the colon and affects the inner layer of its lining. Crohn's disease can affect any part of the digestive tract and causes damage that penetrates deeper into the lining.
  • In ulcerative colitis, the entire colon is affected. In Crohn's disease, the damage generally occurs in patches.
Mice are often used in medical experiments.
Public domain photo by auenleben

The Soy Protein Research

The Penn State researchers studied both mice and isolated cells from the human colon. They found that concentrated soy protein produced protective effects in the colon cells. The researchers replaced some of the protein in the diet of the mice with soy protein concentrate. They tried to keep the quantity of soy reasonable instead of using a huge amount. Not only did the intestinal inflammation improve in the mice with induced IBD, but in addition weight loss and spleen swelling were reduced.

Since soy protein is available commercially, both in the form of a protein powder and in meat substitute products, people with IBD may want to try it now to see if it helps them. If this is done, it's probably a good plan to start with a small amount at first to see how the body reacts. If the condition doesn't worsen, the amount of soy that's ingested could be increased. A huge amount of soy may not be good for other aspects of health, however. It might be a good idea for a patient to talk to their doctor before incorporating the protein into the diet. Hopefully the clinical trials will be performed as soon as possible in order to determine the optimal amount of protein, assuming it helps humans as it does mice.


Friday, 28 April 2017

Marmite, GABA, and Improved Brain Function

Marmite on toast ready for me to eat
Photo by Linda Crampton

A Potentially Helpful Sandwich Spread

Marmite is a dark brown spread with a strong taste that some people love and others hate. Research performed by scientists at the University of York in Britain suggests that eating marmite can be beneficial for brain function, possibly by stimulating the production of a chemical known as GABA.

Half of the subjects in the British experiment ate a teaspoon of marmite every day for a month in addition to their normal diet; the other subjects added a daily teaspoon of peanut butter to 
their diet instead of marmite. At the end of the month, the researchers found that the people who ate marmite had an approximately thirty percent reduction in their brain's response to visual stimulation caused by an image of flickering stripes. This was demonstrated by detecting the electrical activity in the brain via electroencephalography, or EEG.

What Is GABA?

The researchers believe that the decreased brain activity in the subjects occurred because the marmite stimulated the production of GABA. "GABA" is an abbreviation that stands for gamma-aminobutyric acid. The chemical is a neurotransmitter. Neurotransmitters control the passage of a nerve impulse from one neuron (nerve cell) to another. Some transmit the impulse and are said to be excitatory. Others stop the transmission and are said to be inhibitory. GABA is an inhibitory neurotransmitter. It night sound bad that a chemical stops the passage of a nerve impulse, but that's exactly what sometimes needs to happen in order to quell overactivity in the nervous system. 

GABA is often low in people with epilepsy, as is taurine. Its role in the disorder isn't fully understood, however. It's very important that someone with epilepsy or a seizure disorder doesn't take GABA or taurine supplements without their doctor's supervision. According to the University of Maryland Medical Center, there is no scientific evidence that supplements containing the chemicals will reduce the number of seizures. 

DO NOT take taurine or GABA supplements without your doctor's supervision. DO NOT take taurine or GABA if you have a history of bipolar disorder, or if you take psychoactive medications. (Quote from the University of Maryland Medical Center)

Some Unanswered Questions

The results of the marmite experiment are interesting and could be important, but there are some unanswered questions relating to the research.

  • Although the researchers think that the vitamin B12 in the marmite was the helpful component of the spread (because it triggered the production of GABA), this wasn't tested. Another substance may have been responsible for the benefit. It's also possible that a combination of chemicals produced the benefit.
  • The proposal that the marmite exerted its effect by triggering GABA production wasn't tested. 
  • Only twenty-eight people were involved in the research (fourteen in each group). The experiment needs to be repeated with a larger sample size.
Thickly spread marmite
Photo by TheJackal, CC BY-SA 3.0 License

The Nature of Marmite 

Marmite is a yeast extract. For some people, eating a whole teaspoon of the spread all at once would be difficult because of its strong and often overpowering taste. I love marmite myself, but I spread it very thinly on my bread, as shown in my photo at the start of this article. I would find it very hard to eat the thick layer shown in the photo above. I suspect that some marmite haters might like the product if they ate a thin layer instead of a thick one

The marmite that's sold in Britain contains added B vitamins, including vitamin B12. The version that's sold in Canada, where I live, doesn't contain these additions. I can get British marmite only if I go to a food import store instead of my local supermarkets. I sometimes do this, but I usually buy the product locally. It would be nice if it was beneficial for brain health as well as being tasty. It would also be nice to know if the marmite version with added vitamins is necessary in order to get the special health benefit discovered in the research.


Marmite may affect brain function from ScienceDaily

Marmite may be brain food from CTV News

Seizure disorders from the University of Maryland Medical Center