Tag Archives: bacteria

Implants Without Risk Of Infection

Researchers at McMaster (Canada) have solved a vexing problem by engineering surface coatings that can repel everything, such as bacteria, viruses and living cells, but can be modified to permit beneficial exceptionsThe discovery holds significant promise for medical and other applications, making it possible for implants such as vascular grafts, replacement heart valves and artificial joints to bond to the body without risk of infection or blood clotting. The new nanotechnology has the potential to greatly reduce false positives and negatives in medical tests by eliminating interference from non-target elements in blood and urine.

The research adds significant utility to completely repellent surfaces that have existed since 2011. Those surface coatings are useful for waterproofing phones and windshields, and repelling bacteria from food-preparation areas, for example, but have offered limited utility in medical applications where specific beneficial binding is required

 

It was a huge achievement to have completely repellent surfaces, but to maximize the benefits of such surfaces, we needed to create a selective door that would allow beneficial elements to bond with those surfaces,” explains Tohid Didar of McMaster’s Department of Mechanical Engineering and School of Biomedical Engineering, the senior author of a paper that appears today in the journal ACS Nano.

In the case of a synthetic heart valve, for example, a repellent coating can prevent blood cells from sticking and forming clots, making it much safer.

A coating that repels blood cells could potentially eliminate the need for medicines such as warfarin that are used after implants to cut the risk of clots,” says co-author , a McMaster PhD student in Biomedical Engineering. Still, she explains, a completely repellent coating also prevents the body from integrating the new valve into the tissue of the heart itself.

By designing the surface to permit adhesion only with heart tissue cells, the researchers are making it possible for the body to integrate the new valve naturally, avoiding the complications of rejection. The same would be true for other implants, such as artificial joints and stents used to open blood vessels.

If you want a device to perform better and not be rejected by the body, this is what you need to do,” says co-author Maryam Badv, also a McMaster PhD student in Biomedical Engineering. “It is a huge problem in medicine.”

Source: https://brighterworld.mcmaster.ca/

Alzheimer’s May Be Caused By Dental Infection

In a new study scientists reveal yet another reason to keep up on dental hygiene. Bacteria that cause a common yet largely preventable gum infection may also play a role in Alzheimer’s disease. The discovery also offers hope for a treatment that could slow neurodegeneration.

There were many clues in the [features of Alzheimer’s disease] that an infection is at work,” said Casey Lynch, an entrepreneur and co-founder of Cortexyme, a biotech company headquartered at the Verily Life Sciences campus in South San Francisco, who led the new research. “Many of the genetic risk factors for Alzheimer’s are related to immune system function,” she added, which suggests “immune system dysfunction might put people more at risk.

Alzheimer’s disease, an irreversible and progressive brain disorder that leads to memory loss and diminished thinking skills, affects at least 5 million Americans. Clumps of a brain protein known as amyloid plaques are a hallmark sign of the disease. Billions of research dollars have gone towards finding a treatment that destroys these mind-robbing masses. But there’s still no cure.

Not enough people are asking what is upstream of the plaques … and [brain] inflammation,” said Lynch, who has a background in Alzheimer’s research and was frustrated by the string of failed therapies for the disease. Nearly six years ago, Lynch received a call from Stephen Dominy, a psychiatrist at the University of California, San Francisco, who had studied the link between HIVand dementia.

I think I’ve found a bacterial cause of Alzheimer’s,” Dominy, who co-foundedCortexyme with Lynch and now serves as the company’s Chief Scientific Officer, told her. Dominy had spent about 15 years searching for infections that might lead to Alzheimer’s until evidence for a bacterium known as P. gingivalis became “undeniable,” according to Lynch. P. gingivalis causesperiodontitis, an infection that destroys the gums and can lead to tooth loss.

When the team examined the brains and cerebrospinal fluid of Alzheimer’spatients, they found DNA from the bacterium. They also discovered bacterial enzymes called gingipains that destroy brain cells were present, too. And when they watched P. gingivalis infections play out in mice, it triggered neurodegeneration in the hippocampus, a brain structure central to memory. It also led to Alzheimer’s hallmark amyloid beta plaqueproduction and inflammation, the researchers discovered.

The scientists then designed and created a new molecule that blocks the gingipain enzymes. The antibiotic reduced the amount of bacteria ininfected mice and stopped the formation of amyloid beta plaques whilereducing inflammation, the team reports Wednesday in the journal Science Advances.

Source: https://www.discovermagazine.com/

An army of microrobots can wipe out dental plaque

A sometimes unpleasant scraping with mechanical tools to remove plaque from teeth. What if, instead, a dentist could deploy a small army of tiny robots to precisely and non-invasively remove that buildup? A team of engineers, dentists, and biologists from the University of Pennsylvania developed a microscopic robotic cleaning crew. With two types of robotic systems—one designed to work on surfaces and the other to operate inside confined spaces—the scientists showed that robots with catalytic activity could ably destroy biofilms, sticky amalgamations of bacteria enmeshed in a protective scaffolding. Such robotic biofilm-removal systems could be valuable in a wide range of potential applications, from keeping water pipes and catheters clean to reducing the risk of tooth decay, endodontic infections, and implant contamination.

The work, published in Science Robotics, was led by Hyun (Michel) Kooof the School of Dental Medicine and Edward Steager of the School of Engineering and Applied Science.

With a precise, controlled movement, microrobots cleared a glass plate of a biofilm, as shown in this time-lapse image

This was a truly synergistic and multidisciplinary interaction,” says Koo. “We’re leveraging the expertise of microbiologists and clinician-scientists as well as engineers to design the best microbial eradication system possible. This is important to other biomedical fields facing drug-resistant biofilms as we approach a post-antibiotic era.

Treating biofilms that occur on teeth requires a great deal of manual labor, both on the part of the consumer and the professional,” adds Steager. “We hope to improve treatment options as well as reduce the difficulty of care.”

Biofilms can arise on biological surfaces, such as on a tooth or in a joint or on objects, like water pipes, implants, or catheters. Wherever biofilms form, they are notoriously difficult to remove, as the sticky matrix that holds the bacteria provides protection from antimicrobial agents.

In previous work, Koo and colleagues have made headway at breaking down the biofilm matrix with a variety of outside-the-box methods. One strategy has been to employ iron-oxide-containing nanoparticles that work catalytically, activating hydrogen peroxide to release free radicals that can kill bacteria and destroy biofilms in a targeted fashion.

Serendipitously, the Penn Dental Medicine team found that groups at Penn Engineering led by Steager, Vijay Kumar, and Kathleen Stebe were working with a robotic platform that used very similar iron-oxide nanoparticles as building blocks for microrobots. The engineers control the movement of these robots using a magnetic field, allowing a tether-free way to steer them.

Together, the cross-school team designed, optimized, and tested two types of robotic systems, which the group calls catalytic antimicrobial robots, or CARs, capable of degrading and removing biofilms. The first involves suspending  iron-oxide nanoparticles in a solution, which can then be directed by magnets to remove biofilms on a surface in a plow-like manner. The second platform entails embedding the nanoparticles into gel molds in three-dimensional shapes. These were used to target and destroy biofilms clogging enclosed tubes.

Source: https://penntoday.upenn.edu/

Periodontal Bacteria May Trigger Alzheimer’s

Long-term exposure to periodontal disease bacteria causes inflammation and degeneration of brain neurons in mice that is similar to the effects of Alzheimer’s disease in humans, according to a new study from researchers at the University of Illinois at Chicago (UIC).

The findings, which are published in PLOS ONE, suggest that periodontal disease, a common but preventable gum infection, may be an initiator of Alzheimer’s, which currently has no treatment or cure.

Other studies have demonstrated a close association between periodontitis and cognitive impairment, but this is the first study to show that exposure to the periodontal bacteria results in the formation of senile plaques that accelerate the development of neuropathology found in Alzheimer’s patients,” said Dr. Keiko Watanabe, professor of periodontics at the UIC College of Dentistry and corresponding author on the study.

This was a big surprise,” Watanabe said. “We did not expect that the periodontal pathogen would have this much influence on the brain, or that the effects would so thoroughly resemble Alzheimer’s disease.

To study the impact of the bacteria on brain health, the Watanabe and her colleagues — including Dr. Vladimir Ilievski, UIC research assistant professor and co-author on the paper — established chronic periodontitis, which is characterized by soft tissue damage and bone loss in the oral cavity, in 10 wild-type mice. Another 10 mice served as the control group. After 22 weeks of repeated oral application of the bacteria to the study group, the researchers studied the brain tissue of the mice and compared brain health.

The researchers found that the mice chronically exposed to the bacteria had significantly higher amounts of accumulated amyloid beta — a senile plaque found in the brain tissue of Alzheimer’s patients. The study group also had more brain inflammation and fewer intact neurons due to degeneration.

Source: https://today.uic.edu/

How To Regenerates Dental Pulp-Like Tissue

When a tooth is damaged, either by severe decay or trauma, the living tissues that comprise the sensitive inner dental pulp become exposed and vulnerable to harmful bacteria. Once infection takes hold, few treatment options—primarily root canals or tooth extraction—are available to alleviate the painful symptoms.

Researchers at Tufts University School of Dental Medicine (TUSDM) now show that using a collagen-based biomaterial to deliver stem cells inside damaged teeth can regenerate dental pulp-like tissues in animal model experiments. The study, published online in the Journal of Dental Research , supports the potential of this approach as part of a strategy for restoring natural tooth functionality.

Delivering stem cells into damaged teeth may someday help restore natural tooth function. An x-ray of deep dental decay (green arrow) and infection (blue arrows)

Endodontic treatment, such as a root canal, essentially kills a once living tooth. It dries out over time, becomes brittle and can crack, and eventually might have to be replaced with a prosthesis,” said senior study authorPamela Yelick, PhD, professor at TUSDM and director of its Division of Craniofacial and Molecular Genetics. “Our findings validate the potential of an alternative approach to endodontic treatment, with the goal of regenerating a damaged tooth so that it remains living and functions like any other normal tooth.”

Yelick and her colleagues, including lead study author Arwa Khayat, former graduate student in dental research at TUSDM, examined the safety and efficacy of gelatin methacrylate (GelMA)—a low-cost hydrogel derived from naturally occurring collagen—as a scaffold to support the growth of new dental pulp tissue. Using GelMA, the team encapsulated a mix of human dental pulp stem cells—obtained from extracted wisdom teeth—and endothelial cells, which accelerate cell growth. This mix was delivered into isolated, previously damaged human tooth roots, which were extracted from patients as part of unrelated clinical treatment and sterilized of remaining living tissue. The roots were then implanted and allowed to grow in a rodent animal model for up to eight weeks.

Source: https://now.tufts.edu/

How To Treat Oral Plaque Without Drugs

When the good and bad bacteria in our mouth become imbalanced, the bad bacteria form a biofilm (aka plaque), which can cause cavities, and if left untreated over time, can lead to cardiovascular and other inflammatory diseases like diabetes and bacterial pneumonia.

A team of researchers from the University of Illinois has recently devised a practical nanotechnology-based method for detecting and treating the harmful bacteria that cause plaque and lead to tooth decay and other detrimental conditions.

Oral plaque is invisible to the eye so dentists currently visualize it with disclosing agents, which they administer to patients in the form of a dissolvable tablet or brush-on swab. While useful in helping patients see the extent of their plaque, these methods are unable to identify the difference between good and bad bacteria.

In this illustration, nanoparticles attach to or are taken up by the bacteria cells. Pan and his students are the first group to demonstrate that early detection of dental plaque in the clinic is possible using the regular intraoral X-ray machine which can seek out harmful bacteria populations.

Presently in the clinic, detection of dental plaque is highly subjective and only depends on the dentist’s visual evaluation,” said Bioengineering Associate Professor Dipanjan Pan, head of the research team. “We have demonstrated for the first time that early detection of dental plaque in the clinic is possible using the regular intraoral X-ray machine which can seek out harmful bacteria populations.

In order to accomplish this, Fatemeh Ostadhossein, a Bioengineering graduate student in Pan’s group, developed a plaque detection probe that works in conjunction with common X-ray technology and which is capable of finding specific harmful bacteria known as Streptococcus mutans (S. mutans) in a complex biofilm network. Additionally, they also demonstrated that by tweaking the chemical composition of the probe, it can be used to target and destroy the S. mutans bacteria.

The probe is comprised of nanoparticles made of hafnium oxide (HfO2), a non-toxic metal that is currently under clinical trial for internal use in humans. In their study, the team demonstrated the efficacy of the probe to identify biochemical markers present at the surface of the bacterial biofilm and simultaneously destroy S. mutans. They conducted their study on Sprague Dawley rats.

In practice, Pan envisions a dentist applying the probe on the patient’s teeth and using the X-ray machine to accurately visualize the extent of the biofilm plaque. If the plaque is deemed severe, then the dentist would follow up with the administering of the therapeutic HfO2 nanoparticles in the form of a dental paste.

In their study, the team compared the therapeutic ability of their nanoparticles with Chlorhexidine, a chemical currently used by dentists to eradicate biofilm. “Our HfO2nanoparticles are far more efficient at killing the bacteria and reducing the biofilm burden both in cell cultures of bacteria and in [infected] rats,” said Ostadhossein, noting that their new technology is also much safer than conventional treatment.

Source: https://bioengineering.illinois.edu/

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