The sense of smell uses fast dynamics to encode odors

Neuroscientists from the John B. Pierce Laboratory and Yale School of Medicine have discovered that mice can detect minute differences in the temporal dynamics of the olfactory system, according to research that will be published in the open access journal PLOS Biology.

The research team used light in genetically-engineered mice to precisely control the activity of neurons in the olfactory bulbs in mice performing a discrimination task. This approach to controlling neural activity, called optogenetics, allows for much more precise control over the activity of neurons of the olfactory system than is possible by using chemical odors. The “light-smelling” mice were able to detect differences as small as 13 milliseconds between the dynamics of these “virtual odors”.

Because olfactory bulbs exhibit dynamic neural activations in the range of many tens of milliseconds, the 13 millisecond detection limit suggested that mice should be able to discriminate these dynamics. The researchers tested this hypothesis by recording brief “movies” of the dynamic activity in the olfactory bulbs of one group of mice and projecting them back onto the olfactory bulbs of another group of naïve mice. The naïve mice were indeed able to discriminate between the movies, demonstrating that the neural dynamics of the bulb contain fundamental information about odors.

“This data is very exciting as it shows for the first time that the temporal dynamics of bulbar neural activity are meaningful to the animal”, remarked Associate Professor Justus Verhagen, the lead author on the paper. “Before optogenetics arrived as a new tool we had no means to test if this was true, we could read out the dynamic activity but could not impose it back on the brain and ask questions about its role in odor discrimination “.

These new findings build upon earlier evidence that olfactory processing in mice included temporal information about sniffs. “We knew from prior work by the team of Dr. Dima Rinberg that mice could accurately determine when their olfactory system was stimulated relative to the timing of sniffs. We now know that mice can also obtain this information directly by comparing the timing of activities among neurons. We hence think that the neural population dynamics are important for the sense of smell both independently of and relative to sniffing. Thus, a sniff can be the “start” signal from which the brain begins to analyze the times at which different neurons turn on, but the brain can also do this independently of the sniff by using the earliest neural activations themselves as “start” signals. Combined these mechanisms provide for a very robust means for the brain to use time information. However, we don’t yet know how these two forms of temporal information may interact”.

Dr. Verhagen’s lab is one of several at Yale and the John B. Pierce Laboratory that are studying the neurobiology of food and flavor perception. His lab is unique in applying the power of optogenetics in mice to study the spatio-temporal capabilities of the olfactory neural circuitry that underlies these vital perceptual functions.

Adapted by MNT from original media release

http://www.medicalnewstoday.com/releases/287083.php

Could HIV make hearing worse?

Human immunodeficiency virus can be incredibly debilitating, leaving individuals vulnerable to serious illnesses. On top of this, researchers have now suggested that adults with the virus have poorer low- and high-frequency hearing than adults who do not have the disease.

 

The findings, published in JAMA Otolaryngology – Head and Neck Surgery, come after an evaluation of the pure-tone hearing thresholds of men and women, some with the human immunodeficiency virus (HIV+) and some without (HIV-).

HIV is a virus that impairs the immune system, making people with the condition increasingly susceptible to infection and disease. There is currently no cure, but HIV+ individuals can be given a combination of medicines called highly active antiretroviral therapy (HAART) to slow the spread of the virus.

Since HAART became widely used, there has been very little investigation into the relationship between HIV infection and hearing loss, according to the study authors.

“There have been limited data obtained on the effects of HIV-related medication use on hearing loss,” they write, “and in the few published studies, it is difficult to attribute the increases in hearing loss specifically to HIV medication use rather than age or cumulative noise exposure.”

Dr. Peter Torre III, of San Diego State University in California, and colleagues set out to determine whether HIV disease variables and HAART are associated with changes to pure-tone threshold levels – the softest sounds audible to individuals for the majority of the time.

Evaluating the pure-tone threshold averages

For the study, the researchers assessed the hearing of 262 men with an average age of 57 and 134 women with an average age of 48.

Of the men, 117 (44.7%) were HIV+, and of the women, 105 (78.4%) were HIV+. Participants were taken from the sites of the Multicenter AIDS Cohort Study and the Women’s Interagency HIV Study.

Pure-tone threshold levels were measured in both ears in a sound-treated room. The researchers tested a wide range of frequencies, from 250 Hz to 8,000 Hz.

The researchers discovered that high- and low-frequency pure tone averages (LPTA and HPTA) were significantly higher in the better ears of the HIV+ participants, indicating that their hearing was poorer than the HIV- participants.

Even after adjusting the findings for current CD4+ cell count, HIV viral load and long-term exposure to antiretroviral medication, the results remained the same.

“To our knowledge, this is the first study to demonstrate that HIV+ individuals have poorer hearing across the frequency range after many other factors known to affect hearing have been controlled for,” write the authors.

Poorer hearing also found in individuals with diabetes mellitus

“The participants were middle-aged,” write the authors, “so an HIV effect on LPTA was not expected, given the speculation that long-term [HAART] exposure or HIV itself contributes to premature aging.”

Although unexpected, the authors also note that hearing loss at both LPTA and HPTA has previously been observed to be more likely in adults with diabetes mellitus. “It is possible that both HIV infection and diabetes, being systemic diseases, could affect the neural function of the cochlea,” they suggest.

The study is limited by the fact that participants were only recruited from specific geographical areas, namely Baltimore, MA, and Washington, DC. For women, the ratio of HIV+ to HIV- participants was also uneven, and future studies could rectify these representational imbalances.

“Although we do not understand the mechanism of hearing loss found in our study, our results suggest that HIV+ individuals may have physiologic changes that mimic other chronic conditions that affect hearing levels,” conclude the authors.

Earlier this month, Medical News Today reported on a mouse study suggesting hearing loss could be prevented by a vitamin supplement that protects the nerves stimulating the cochlea.

Written by James McIntosh

 

 

More than three years after pulsed-KTP laser treatment, 96 percent of patients with early vocal-cord tumors are cancer-free

The first long-term study of a pioneering endoscopic laser treatment for early vocal-cord cancer, developed at Massachusetts General Hospital (MGH) and previously shown to provide optimal voice outcomes, finds that it is as successful as traditional approaches in curing patients’ tumors while avoiding the damage to vocal quality caused by radiotherapy or by conventional laser or cold-instrument surgery. The report in the December Annals of Otology, Rhinology & Laryngology describes results for the first 117 patients treated for vocal-cord cancer with the green-light potassium-titanyl-phosphate (KTP) laser by Steven Zeitels, MD, director of the MGH Voice Center and developer of the procedure.

“Use of the KTP laser, which eradicates blood vessels in a process called photoangiolysis, was conceived to treat vascular malformations in infants’ delicate skin; but we have demonstrated that this specialized laser is especially effective in treating vocal-cord cancer,” says Zeitels. “These tumors have a denser blood supply than the underlying vocal-cord tissue, preservation of which is necessary to retain optimal vocal quality. As reported in this paper, our success in curing patients with small tumors with the angiolytic KTP laser is extremely high and very high for those with mid-sized tumors.

“Since radiation can damage the non-cancerous tissue of one or both vocal cords and conventional laser surgery destroys more delicate vocal tissue than is necessary, KTP laser treatment typically produces better vocal results while being more cost-effective,” he adds. “And a key issue when selecting a treatment for vocal-cord cancer is that radiation is considered to be a single-use treatment. So it is important to preserve the option of radiotherapy for treating future, more substantial cancers, the development of which is not uncommon.”

Zeitels first reported the use of the yellow-light, pulsed-dye laser to treat early vocal-cord cancer ten years ago, and in 2006 he and his colleagues introduced treatment with the more precise green-light KTP laser. Initial results with the KTP laser, describing the outcomes for 22 patients an average of 27 months after their procedures, were announced at the 2008 American Broncho-Esophagological Association (ABEA) annual meeting and published in Annals of Otology, Rhinology & Laryngology. A 2013 paper in the same journal reported excellent vocal outcomes for the first 92 treated patients, but neither paper included the kind of follow-up data required to confirm the treatment’s long-term effectiveness in curing the tumors.

The current paper describes results for 117 patients treated with the green-light KTP laser between 2006 and 2010. Some had cancer invading both vocal cords, but none had received radiotherapy before the laser treatment. Of the 82 treated patients with small tumors, 96 percent (79 of 82) have had no recurrence more than three years after treatment, and 80 percent (28 of 35) of those with mid-size tumors also have had no recurrence. Among the 10 patients whose tumors did recur, radiation treatment was successful in controlling the cancer in 5. Overall 96 percent – 112 of 117 patients – of those treated have survived an average of almost four and a half years and are cancer-free without loss of their larynx. At this year’s ABEA annual meeting the researchers received the organization’s prestigious Broyles Maloney Award for their successful development of this innovative, minimally-invasive strategy for treating vocal cord cancer.

Since 2010, more than 75 additional patients have received pulsed-KTP laser treatment for early vocal-cord cancer at MGH. Zeitels recently treated a 13-year-old boy with vocal-cord cancer, a rare condition in one so young. The first child to receive the KTP laser cancer treatment, he was referred to Zeitels after cancer was discovered in a biopsy of what were originally believed to be benign human papilloma virus (HPV) warts. While in only the first months after treatment for tumors involving both vocal cords, the youth’s voice has returned to near normal for a young man of his age. (An endoscopic video showing before-and-after results for this patient may be viewed here:

Another important aspect of the green-light KTP laser approach, Zeitels adds, is that biopsy and treatment of patients whose cancer involves a single vocal cord usually can be accomplished in the same procedure, whereas radiotherapy requires a prior biopsy to determine the extent and location of the tumor, followed by daily radiation treatments over approximately six weeks. For patients with tumors involving both vocal cords, a planned second-stage KTP laser treatment is done to optimize their voice outcomes. In addition, Zeitels notes, the treatment’s mechanism of eradicating the blood vessels supplying a tumor – highly effective for conventional vocal-cord cancer – is even more useful for treating tumors caused by HPV infection, which are characterized by an excessive overgrowth of blood vessels.

Adapted by MNT from original media release

http://www.medicalnewstoday.com/releases/286774.php

 

 

Racial disparities in ear infection treatment may contribute to antibiotic overuse

Black children are less likely to be diagnosed with and less likely to receive broad-spectrum antibiotics for ear infections than white children are, a new study has found. But the discrepancy in prescribing fewer broad-spectrum antibiotics means black children actually are more likely to receive care that aligns with the recommended guidelines for treating ear infections.

Two explanations for the observed disparities in care are overtreatment and overdiagnosis in white children, and undertreatment and underdiagnosis in black children. Addressing behaviors that contribute to these findings may cut down on differential care and antibiotic overuse, both significant public health concerns.

Led by researchers at the University of Utah, Emory University, and the Centers for Disease Control and Prevention (CDC), the study appears online in Pediatrics.

“These findings raise the possibility that physicians bring with them to the exam room cultural and racial biases that influence how they make a diagnosis and prescribe antibiotics,” says senior author Adam Hersh, M.D., Ph.D., assistant professor of pediatrics at the University of Utah School of Medicine.

Examination of medical records from across the nation shows that when children were brought to the doctor for upper respiratory infections that commonly lead to ear infections, 30 percent fewer black children (African-American and other black racial backgrounds) were diagnosed with ear infections compared to other children (95 percent white, 5 percent of other non-black racial backgrounds). Once diagnosed with an ear infection, black children were 20 percent less likely to receive a prescription for broad-spectrum antibiotics.

The results indicate that, whether intentional or not, black children are more likely to receive care that aligns with current ear infection treatment guidelines, which specifically recommend a prescription of narrow-spectrum antibiotics, rather than broad-spectrum antibiotics, as first-line treatment. What’s more, fewer ear infection diagnoses among black children suggest that in some cases, ear infections may be overdiagnosed in other children.

“These findings may indicate racial differences in the diagnosis of otitis media,” says first author Katherine Fleming-Dutra, M.D., pediatric emergency fellow at Emory University and Children’s Healthcare of Atlanta. “Additionally they may reflect inappropriate treatment of otitis media with the use of broad-spectrum antibiotics in a majority of U.S. children.”

Guidelines for treating ear infections have been updated in recent years in an effort to confront antibiotic overuse. Ear infections can be difficult to accurately diagnose, and it can be hard to distinguish bacterial from viral infections. Physicians sometimes err on the side of prescribing antibiotics when the diagnosis is uncertain, even though they are ineffective against viral infections. Overprescribing antibiotics, and unnecessary use of broad-spectrum antibiotics, can lead to adverse side effects such as severe diarrhea, and development of antibiotic-resistant bacteria.

“The use of antibiotics is the single most important driver of antibiotic resistance. Further, ear infections lead to more antibiotic prescriptions in the United States than any other diagnosis,” says co-author Lauri Hicks, D.O., medical director of Center for Disease Control’s Get Smart: Know When Antibiotics Work program. “By increasing our knowledge base about antibiotic prescribing behaviors, we can develop tools and interventions to improve antibiotic prescribing.”

The results were derived from a sample of 15,694 doctor visits for respiratory infections and 4,178 visits for ear infections made by children age 14 years and younger between the years 2008 to 2010. The samples extrapolate to a national estimate of 23.5 million, and 6.4 million annual visits, respectively.

Though not directly addressed by the study, one explanation for disparities in treatment are biases toward children and families of different races. “Overtreatment and overdiagnosis could result from the possibility that in some circumstances, parents may expect an antibiotic prescription, or physicians may perceive that they do,” says Hersh. “Physicians may tailor their diagnosis based on these perceptions of patient expectations.”

Another explanation, underdiagnosis of ear infection and undertreatment with broad-spectrum antibiotics, could result from a number of factors including differences in how frequently parents of black children seek care for their children with respiratory infections, or return for follow-up visits. Racial differences in the reported rate of medication allergies could also influence the choice of antibiotics.

The authors found that equal proportions of black children and children of other races made visits to the doctor for respiratory infections, suggesting that lower rates of ear infection diagnoses in black children are not the result of decreased access to care. But limitations to the analysis include an inability to determine whether the visits were first or follow-up visits, and whether patients had allergies, both of which could impact treatment.

“It is important to understand why certain children are not getting guideline-recommended antibiotics so that we can focus public health efforts to help providers improve their diagnosis and selection of antibiotics for children with otitis media,” says Fleming-Dutra.

http://www.medicalnewstoday.com/releases/285552.php

 

Picture courtesy to articles.mercola.com

 

 

Women’s finer sense of smell may be due to more brain cells

w research shows that women have more cells in the olfactory bulb – the area of the brain that is dedicated to sense of smell – than men. The authors of the study – published in PLOS ONE – suggest this may explain why women are reported to have a better sense of smell than men.

 

The study was led by a team from the Federal University of Rio de Janeiro in Brazil, where another group of researchers had developed the “isotropic fractionator” – a fast and reliable method of measuring the number of cells in a given brain region such as the olfactory bulb.

The olfactory bulb is the first region of the brain to receive signals about odors sensed via the nostrils. The ability to discriminate among odors and scents varies widely among individuals. Also, studies show marked differences between men and women, with women often outperforming men in many kinds of odor-sensing tests.

There are theories that sex differences in smell are due to cognitive and emotional influences rather than perceptual ability.

Previous studies that have looked for biological explanations for women’s apparent superior sense of smell have used brain scans to look for structural and volume differences. These have led to mixed results and left many questions still unanswered.

So Roberto Lent, a professor in the Institute of Biomedical Sciences at Rio’s Federal University, and colleagues set out to measure the biological evidence more directly – by counting the number of cells in women’s and men’s olfactory bulbs.

To this end they examined post-mortem brains from seven men and 11 women who were all healthy and aged over 55 when they died. None of the subjects had worked in jobs that required them to have exceptional sense of smell such as cookery or coffee-tasting.

Study found women’s brains have up to 50% more olfactory neurons

Using the isotropic fractionator, the team calculated the number of cells in the olfactory bulbs of these individuals and found that, on average, the women had 43% more cells in this brain region than the men. When they included only neurons in the count – that is leaving out other cells like glial or structural cells – this figure went up to nearly 50%.

The authors acknowledge that just finding this difference is not enough to prove that women have a superior sense of smell – it is not even enough to explain the findings of previous studies about differences in ability to differentiate, identify and remember scents and odors. However, Prof. Lent suggests:

“Generally speaking, larger brains with larger numbers of neurons correlate with the functional complexity provided by these brains. Thus, it makes sense to think that more neurons in the female olfactory bulbs would provide women with higher olfactory sensitivity.”

Since the brain does not accumulate many more cells as we grow, it would seem that women are equipped with these extra olfactory cells from the day they are born.

There are still many questions to explore, including why women should have this ability hard-wired into their brains, and what mechanism produces this greater quantity of olfactory cells in the female brain.

One theory is that a superior sense of smell helps mother and child to bond after birth; another is it also influences females’ selection of potential mates.

In October 2012, Medical News Today learned of another PLOS ONE study from the University of Pennsylvania that suggested losing sense of smell could be an early sign of Parkinson’s or Alzheimer’s disease, or another neurodegenerative disorder.

Written by Catharine Paddock PhD

http://www.medicalnewstoday.com/articles/284991.php

 

 

Noise-induced hearing loss restored in mice

searchers from the University of Michigan and Harvard Medical School in Boston, MA, may be well on the way to finding new therapies that restore noise-induced and age-related hearing loss in humans. In a new study, the team describes how they recovered hearing in mice partially deafened by noise.

 

The researchers, led by Gabriel Corfas, PhD, of the University of Michigan, publish their findings online in the journal eLife.

Approximately 50 million Americans have hearing loss in at least one ear, with around 26 million Americans aged 20-69 experiencing high-frequency hearing loss as a result of noise exposure. Hearing loss is also common as we age, affecting around 30% of adults aged 65-74 and 47% of adults aged 75 and over.

In their study, the researchers explain how they were able to increase production of a protein called Neurotrophin-3 (NT3) in mice, which they found plays a key role in communication between the ears and the brain.

NT3 allows sound signals to be sent from the ear to the brain. The protein is crucial in establishing a super-fast connection between the ear’s hair cells and nerve cells – a connection the researchers call the “ribbon synapse.” But this ribbon synapse can become damaged as a result of noise exposure or normal aging, which can lead to hearing loss.

Boosting NT3 production in mice

In their study, the researchers identified supporting cells in the inner ear that produce NT3. They set out to see what would happen if they increased production of NT3 through these supporting cells.

Fast facts about hearing loss

• Hearing loss is more common among men than women
• Around 60% of veterans returning from Iraq or Afghanistan have some form of hearing loss ortinnitus – ringing in the ears
• Approximately 2-3 in every 1,000 children in the US are born with detectable levels of hearing loss in one or both ears.

Learn more about hearing loss

They adopted a method called conditional gene recombination. This allows researchers to activate genes in particular cells by administering a drug that prompts the cells to “read” additional copies of a gene that have been inserted into them.

For this study, the team used the technique to activate additional NT3 genes that had been introduced to the supporting cells of the inner ear in mice that had been partially deafened by loud noise.

The drug tamoxifen was introduced to the supporting cells in the inner ear, which prompted them to produce extra NT3 protein. The researchers then tested the hearing of the mice through a test normally used in humans – the auditory brainstem response (ABR).

The researchers found the mice that had experienced boosted NT3 production regained their hearing over a 2-week period, compared with mice that had not had additional NT3 production.

According to the team, these findings indicate that NT3 production is important for making ribbon synapses, and that boosting production of this protein may restore noise-induced and age-related hearing loss.

The potential to restore hearing loss in humans

Corfas and his team say they now plan to investigate the role of NT3 in human ears and identify drugs that produce the same effect as the protein, offering the potential to restore hearing loss in humans.

The researchers note that the gene therapy technique used in this study has the potential to work in humans, but that a drug-based method would be “simpler” and a drug could be repeatedly administered for as long as it takes for hearing to be restored. Corfas says he already has some drug candidates in mind.

The researchers stress, however, that since the mice in this study were only partially deaf, it is unclear whether increased NT3 production would restore hearing in subjects that are fully deaf.

But the team believes their findings are promising. Corfas says:

“It has become apparent that hearing loss due to damaged ribbon synapses is a very common and challenging problem, whether it’s due to noise or normal aging. We began this work 15 years ago to answer very basic questions about the inner ear, and now we have been able to restore hearing after partial deafening with noise, a common problem for people. It’s very exciting.”

Their findings may even reach further than hearing loss. The researchers say they may offer new strategies to treat neurodegenerative diseases, in which nerve cell connections are impaired.

Medical News Today recently reported on a study from the University of Leicester in the UK, in which researchers reveal how loud noises damage hearing in more detail.

Written by Honor Whiteman

http://www.medicalnewstoday.com/articles/284159.php

 

 

Effectiveness of treatment to reduce blood clots in otolaryngology patients admitted for surgery examined

The effectiveness of a treatment to reduce blood clots among otolaryngology patients admitted for surgery appears to differ based on patient risk and the procedure.

Blood clots (venous thromboembolism [VTE], which includes deep vein thrombosis [DVT] and pulmonary embolism[PE]) are common complications in surgical patients. Treatment (primary thromboprophylaxis with anticoagulant medication [chemoprophylaxis]) can help reduce the incidence of VTE in surgical patients. But treatment should be considered in light of the risk of VTE and bleeding complications. The American College of Chest Physician’s guidelines for thromboprophylaxis do not specifically apply to otolaryngology. The authors sought to examine the effectiveness and safety of VTE chemoprophylaxis for otolaryngology patients admitted for surgery.

How the Study Was Conducted:

The study included 3,498 patients treated by surgeons at an academic medical center between September 2003 and June 2010. The authors analyzed the incidence of VTE and bleeding complications within 30 days after surgery.

Results:

Of the 1,482 patients who received VTE chemoprophylaxis, 18 (1.2 percent) developed a VTE compared with 27 of 2,016 patients (1.3 percent) who did not receive treatment. Patients with higher scores on a risk assessment were less likely to have a VTE with perioperative chemoprophylaxis (5.3 percent vs. 10.4 percent). Of the patients who underwent treatment, 3.5 percent developed a bleeding complication compared with 1.2 percent of patients without treatment. Among patients who underwent free tissue transfer, treatment decreased the incidence of VTE (2.1 percent vs. 7.7 percent) and increased bleeding complications (11.9 percent vs. 4.5 percent). In all other patients, treatment did not significantly influence the likelihood of VTE (1 percent vs. 0.6 percent) or bleeding (1.5 percent vs. 0.9 percent).

Discussion:

“Results from this study provide the basis for future research. … An examination of additional benefits and harms of VTE prophylaxis is warranted, including its impact on mortality due to PE. Free tissue transfer patients merit special analysis when developing recommendations for VTE prophylaxis because of the high risk of both VTE and bleeding. … Finally, further tests of the incidence of VTE by risk level and of the effectiveness and safety of chemoprophylaxis should be conducted for other otolaryngology patients, in populations large enough to produce sufficiently powered analyses.”

http://www.medicalnewstoday.com/releases/283314.php

 

Viral infection causes bacteria to colonize privileged sites like the middle ear

Influenza infection can enhance the ability of the bacterium Streptococcus pneumonia to cause ear and throat infections, according to research published ahead of print in the journal Infection and Immunity.

In the study, the investigators infected mice with either influenza alone, pneumococci alone, or both at once, and then monitored the populations of bacteria and virus over time. They also monitored the mice for development of middle ear infection.

Influenza infection enhanced the bacterium’s ability to colonize the nasopharynx, and to infect the normally sterile middle ear.

“We learned that once influenza virus is introduced, all of the “rules” regarding phase variants are out the window,” says corresponding author W. Edward Swords of Wake Forest University, Winston-Salem, NC. Phase variation refers to the fact that the colonizing bacteria have transparent cell surfaces, while those that spread within the host have opaque surfaces.

“However, in the presence of influenza, opaque variants can readily colonize the nasopharynx, and transparent variants can persist in the ear,” says Swords. “This indicates that the host environs are more permissive for infection by the entire bacterial population.”

Furthermore, recent research had shown that influenza interferes with innate immunity in a way that enables pneumococci to flourish. In this research, Swords shows that that interference manifests as increased inflammatory responses at the mucosal surface in the influenza-infected mice, such as within the middle ear, and in the nasopharynx.

“As with most pneumococcal infections, it should be appreciated that localized nonlethal infections are much more common than the rapidly lethal presentations,” says Swords. “For example, influenza is a contributing factor in otitis media (middle ear infections) in children.”

“If we can understand why and how viral infection causes bacteria to colonize privileged sites like the middle ear, we will better know what aspects of disease to focus on with preventive or therapeutic treatments,” says Swords.

http://www.medicalnewstoday.com/releases/282910.php

Picture courtesy to www.chori.org

 

 

Tinnitus less common in women who drink more coffee

A new study finds that women who consume more caffeine are less likely to have tinnitus – a condition where a person perceives noise in one or both ears, or in the head, even though there is no external sound.

 

The researchers, from Brigham and Women’s Hospital (BWH) in Boston, MA, write about their findings in The American Journal of Medicine.

According to the American Tinnitus Association, around 50 million people in the US experience some degree of tinnitus, which is often described as “ringing in the ears” although some people also hear hissing, buzzing, roaring, clicking or chirping. Of these, about 1 million are so badly affected they cannot function normally day to day.

For the study, the researchers analyzed data on over 65,000 women with and without tinnitus from the Nurses’ Health Study II.

The women were aged between 30 and 44 at the start of the study in 1991, when researchers collected a wealth of information on medical history, lifestyle and diet. At this point, the average caffeine intake was 242.3 mg per day – the equivalent of nearly two and a half 8-ounce cups of coffee. Most of the caffeine consumed came from coffee drinking.

In 2009, 18 years after they joined the study, the women were asked questions about tinnitus, including date of onset, where applicable. When a woman reported experiencing symptoms either daily or on a few days per week, the researchers counted it as a case. They identified a total of 5,289 cases of reported incident tinnitus.

Women who consumed more caffeine less likely to be among tinnitus cases

When they analyzed the results, the team found the more caffeine women consumed, the less likely they were to be among the tinnitus cases.

Senior author Gary Curhan, a physician-researcher in BWH’s Channing Division of Network Medicine and professor of Medicine at Harvard Medical School, says:

“We observed a significant inverse association between caffeine intake and the incidence of tinnitus among these women.”

He and his and colleagues found that regardless of age, rates of tinnitus were 15% lower among women who consumed 450-599 mg a day of caffeine, compared with women who drank less than 150 mg a day (about one and a half 8-ounce cups of coffee).

Prof. Curham notes that while the reason behind the finding is unclear, we know that “caffeine stimulates the central nervous system, and previous research has demonstrated that caffeine has a direct effect on the inner ear in both bench science and animal studies.”

The researchers say more evidence is required before we can say whether increased caffeine intake might improve tinnitus symptoms.

Funds from the National Institutes of Health helped finance the study.

Medical News Today recently reported on another study where researchers found tinnitus affects processing of emotions. Writing in the journal Brain Research, they describe how, compared with people not affected by the condition, those with tinnitus process emotions differently in the brain.

Written by Catharine Paddock PhD

http://www.medicalnewstoday.com/articles/280775.php

 

 

 

 

Biomarker for head and neck cancers identified

Although mutations in a gene dubbed “the guardian of the genome” are widely recognized as being associated with more aggressive forms of cancer, researchers at the University of California, San Diego School of Medicine have found evidence suggesting that the deleterious health effects of the mutated gene may in large part be due to other genetic abnormalities, at least in squamous cell head and neck cancers.

The study, published online in the journal Nature Genetics, shows that high mortality rates among head and neck cancer patients tend to occur only when mutations in the tumor suppressor gene coincide with missing segments of genetic material on the cancer genome’s third chromosome.

The link between the two had not been observed before because the mutations co-occur in about 70 percent of head and neck tumors and because full genetic fingerprints of large numbers of cancer tumors have become available only recently.

“These two genetic malfunctions are not two separate stab wounds to the body,” said co-senior author Trey Ideker, PhD, chief of the Division of Genetics. “One exposes the Achilles tendon and the other is a direct blow to it.”

To patients with these cancers, the study’s results mean that there may be therapeutic value in testing tumors for the two genetic identifiers, known as a TP53 mutation (short for tumor protein 53) and a 3p deletion (short for deletions of genetic information on the short arm “p” of the third chromosome).

TP53 plays a key role in regulating cell growth, detecting and fixing DNA, and directing cell apoptosis (death) if the DNA damage is irreparable. Because of this, the TP53 protein is sometimes called the “guardian of the genome.”

The study’s findings suggest that if both markers are present, treatment should be intensified. If only one mutation is present, treatment might be de-intensified because the TP53 mutation alone is less deadly than previously thought. The latter would have immediate benefits in reducing deaths caused by complications related to medical care.

“We are in the early stages of being able to personalize head and neck cancer treatments based on the tumor’s actual biology, the same as what’s done with breast cancers,” said co-senior author Quyen Nguyen, MD, PhD, associate professor of Otolaryngology-Head and Neck Surgery. “In the past, treatments have been based largely on the size and location of the tumor. Now, we know that some large tumors may respond to less aggressive treatment while some small tumors may need intensified treatment. This will have a huge impact for patients.”

The study analyzed the complete genomic signatures of 250 cases of squamous cell head and neck cancer extracted from The Cancer Genome Atlas, a repository of sequenced cancer genomes for more than 20 different types of human cancers maintained by the National Institutes of Cancer. All of the tumors were from patients younger than 85 years of age.

Of these, 179 had both mutations; 50 had one of the two mutations; and 22 had neither mutation. Comparisons with patient outcome data showed that half of patients with both mutations would likely die of cancer within 2 years, while 66 percent of patients with one or neither mutation would be expected to live five years or more. These survival statistics were independent of the patients’ clinical cancer stage.

Besides causing cervical cancer, the human papilloma virus (HPV) is implicated in the growing epidemic of head and neck cancers in otherwise healthy adults. It is believed that the virus can co-opt the activity of TP53, affecting cells in much the same way as a TP53 mutation but without causing a mutation. For this reason, the analysis examined HPV-positive and HPV-negative tumors separately.

One of the study’s more compelling discoveries is that among HPV-positive tumors, the most aggressive cancer cases were also highly linked to the presence of 3p deletions.

“Our findings raise fundamental questions about the role of TP53 in cancer and suggest that some of the deleterious health effects of TP53 mutations might actually be due to something else going on in the third chromosome,” said lead author Andrew Gross, a graduate student in the Bioinformatics and Systems Biology Program.

 

http://www.medicalnewstoday.com/releases/280558.php