Have you noticed that your sense of taste can get thrown off when you’re sick with a stuffy nose? That’s because the majority of a food’s flavor comes from our ability to smell it.
Could a similar connection between smell and taste explain why kidney disease patients often lose their interest in food, reporting that it has little flavor or an unpleasant taste? In a recent study published in the Journal of the American Society of Nephrology, Massachusetts General Hospital researchers share new findings about the link between loss of appetite and loss of smell in these patients.
Here are five things to know:
More than 25 million adults in the U.S. have chronic kidney disease, with more than half a million requiring dialysis. While kidney disease is challenging enough on its own, many patients also suffer from malnutrition at the same time. “Poor dietary intake leading to malnutrition is common in these patients, but there currently are no effective treatments addressing these complications,” says first author Sagar Nigwekar, MD, of the Mass General Division of Nephrology. Despite the known connection between sense of smell and taste, little research has been done to investigate the impact of loss of smell on nutrition in patients with kidney disease.
To better understand this potential association, Nigwekar, senior author Teodor Păunescu, PhD, also of Mass General Nephrology, and their team enrolled 160 participants with either end-stage kidney disease on dialysis, chronic kidney disease not yet at the end stage, or healthy control subjects with neither condition. Participants were tested on their ability to identify specific odors as well as the threshold at which they could detect a smell.
The study found that those with end-stage kidney disease had greater abnormalities in their sense of smell. Specifically:
Based on the odor identification tests, almost 70 percent of those with chronic kidney disease and about 90 percent of those with end-stage disease had a significant reduction in their sense of smell.
In the test determining odor detection thresholds, participants with end-stage kidney disease required a four times greater concentration of an aroma in order to detect it than those with chronic disease or control participants.
In all three groups, participants’ nutritional status – determined by a standard assessment of food intake and weight changes, among other factors –correlated with their ability to smell. Those with a better sense of smell had a better nutritional status.
Interestingly, across all three groups, participants’ ratings of their own sense of smell was about the same despite what the laboratory tests showed. Self-assessment scores averaged 80 percent on a scale of 0 to 100, suggesting that most patients were not aware of having problems with their sense of smell.
In the hopes of identifying a potential treatment to improve sense of smell, the team also conducted a small pilot study testing daily intranasal doses of theophylline – a drug approved to treat asthma and emphysema and previously reported to reduce similar sense of smell issues in patients without kidney disease. They found this treatment strategy increased the ability to smell odors in five of the seven participants with dialysis-dependent, end-stage kidney disease.
The team now plans to conduct larger studies to determine the sequence of events between changes in sense of smell, changes in food consumption, and the eventual onset of malnutrition in patients with end-stage kidney disease. They are also excited about further exploring the potential of using drugs such as theophylline to treat kidney disease patients and prevent malnutrition.
In a case of mistaken identity, researchers at Massachusetts General Hospital have found that lymph nodes are not always responsible for cancer’s deadly spread to other organs. These results buck many preconceived notions about lymph nodes’ role in cancer development and suggest a new pattern for the progression of certain types of cancer.
Doctors recognize that patients whose cancer spreads (metastasizes) from the original tumor to the surrounding lymph nodes have a worse prognosis than patients whose lymph nodes are cancer-free. This observation has traditionally been explained by a progression model of primary tumor to nearby lymph nodes to other organs. However, no conclusive evidence for this model has existed so far.
In a new study, researchers from the Edwin L. Steele Laboratories for Tumor Biology in the Mass General Department of Radiation Oncology investigated the “family tree” of metastases in colorectal cancer. Contrary to the prevailing belief that the spread begins in the lymph nodes, they found that the cancer could spread to both the lymph nodes and the organs simultaneously. In their report in the July 7 issue of Science, the researchers describe finding that, for the majority of colorectal cancer patients in the study, organ metastases (also called distant metastases) originated directly from the primary tumor, independent of any lymph node metastases.
“We now suspect that lymph node metastases simply indicate the presence of an aggressive primary tumor, rather than being directly responsible for the formation of distant metastases,” says lead and corresponding author Kamila Naxerova, PhD, Research Fellow at the Steele Labs.
The researchers analyzed more than 200 tissue samples of primary tumors, lymph node metastases and distant metastases from 17 patients with colorectal cancer. Samples from 35 percent of these patients followed the traditional progression model. In these samples, both lymph node and distant metastases came from the same cell type in the primary tumor, indicating that the cancer had spread from the primary tumor to the lymph nodes and then to other organs.
However, in 65 percent of patients, researchers found that cell types in lymph node and distant metastases were different and matched different cell types within the primary tumor, indicating independent origins for these metastasis types.
Their results suggest that although cancer progression can follow the traditional model described above, there is also a second distinct pattern of metastatic spread.
“These findings fill an important gap in our knowledge of metastatic disease evolution and have the potential to guide improvements in the clinical management of lymph node metastases,” says Naxerova.
The research team is now following up with a larger cohort of patients to confirm whether survival differences exist between patients with a traditional progression pattern vs the second progression pattern.
Rakesh K. Jain, PhD, Director of the Steele Labs, was senior author of this paper.
We wanted to share some recent Mass General research that has been published in high impact, top-tier journals. This is just a small snapshot of the incredible research that takes place at Mass General each day — there’s lots more to find at massgeneral.org/research/news!
Summary submitted by Caroline Burns, PhD, d’Arbeloff MGH Research Scholar, and Geoff Burns, PhD, both researchers in the Cardiovascular Research Center at Mass General, and co-senior authors of the study
The aorta and its branches are large arteries in the human body that carry oxygen-rich blood from the heart to the rest of the circulatory system. Structural malformations of the aorta are common birth defects that even in the mildest cases require life-saving surgery at birth. During fetal life, the aorta is built from transient blood vessels termed the pharyngeal arch arteries (PAAs). However, the mechanisms regulating formation of the PAAs remain poorly understood. This paper reports that TGFb signaling, a molecular pathway that controls cellular proliferation and differentiation in other contexts, initiates and is essential for PAA development in zebrafish. Despite this important advance, further research is needed to identify additional molecular pathways that control PAA establishment and to learn if mutations that affect TGFb signaling in humans result in similar aortic deficiencies. This information can be leveraged to develop new therapies for preventing or treating congenital malformations that involve the aorta and its branches.
This study finds evidence that propofol, an anesthetic drug frequently used in clinical practice, disrupts activity in the parts of the brain responsible for awareness and coordination by inducing highly synchronized oscillations within and between these brain structures. The study also found that during recovery of consciousness, these synchronized oscillations dissipate in a distinct “boot-up” sequence, one that did not simply mirror loss of consciousness. This implies that recovering consciousness is not just a passive process, but an active one involving a different set of brain areas responsible for “waking up” the brain. Overall, this study advances understanding of what it means to be unconscious under anesthesia, and establishes principled neurophysiological markers to monitor and manage this state.
Human metabolism is “wired” to allow us to go from rest to running by efficiently burning sugars, fats and proteins to harness their energy. However, patients with certain genetic conditions like McArdle disease who cannot access glycogen stores or mitochondrial disease who have broken respiratory chains have symptoms that are exacerbated by exercise. Scientists from the Mootha lab studied the exercise-induced changes that occur in hundreds of plasma metabolites in healthy individuals, patients who have McArdle disease and mitochondrial disease patients. By comparing these disorders they shed light on the typical metabolic processes that allow us to exercise and also revealed potential disease biomarkers.
Summary submitted by John Stone, MD, MPH, Director of the Clinical Rheumatology in the Rheumatology Unit at Mass General, and lead author of the study
Giant cell arteritis (GCA) is the most common form of blood-vessel inflammation. Complications include blindness and aneurysm. Up to now, the only known effective treatment was a steroid called prednisone which caused many complications. Now a phase 3 clinical trial has confirmed for the first time in the history of this disease that regular treatment with a drug called tocilizumab successfully reduces the need for high-dose steroid treatment. Patients who received tocilizumab plus a prednisone taper were nearly four times more likely to achieve disease remissions compared to those who received prednisone alone. Results of the trial were the basis for the Food and Drug Administration’s approval of tocilizumab to treat GCA in May 2017.
Earlier this week US News & World Report announced its Best Hospitals rankings for 2017-18. We are proud to announce that Massachusetts General Hospital has once again been named among America’s Top Hospitals, earning the number four spot on the honor roll of best hospitals.
Mass General was also among the top hospitals in the country to be ranked across all 16 specialties. The hospital scored in the top ten in ear nose and throat, cardiology and heart surgery, diabetes and endocrinology, gastroenterology and GI surgery, geriatrics, nephrology, neurology and neurosurgery, ophthalmology, orthopedics, psychiatry, pulmonary, rehabilitation and rheumatology.
Of the nearly 5,000 hospitals evaluated, Mass General has consistently placed among the top hospitals on the honor roll since its inception in 1990.
A research team at Massachusetts General Hospital is hoping to create new treatments for shigellosis, a potentially fatal digestive disorder, by factoring in genetic changes that occur in Shigella bacteria during the journey through the human digestive system.
From a human perspective, there is a lot to dislike about Shigella.
The more you learn about these infection-causing microbes, the easier it is to picture them as the dastardly, mustache-twirling villains of the microbial world.
Let’s take a quick look at Shigella’s rap sheet.
Shigella is a group of pathogenic bacteria that has evolved over millions of years specifically to infect humans. It is primarily transmitted through contaminated food or water, but it can also be transmitted through surface contact.
A shigellosis infection can cause a bad case of diarrhea, fever and stomach cramps that lasts from five to seven days. Shigella causes about 500,000 cases of diarrhea in the United States annually. Fortunately, most cases resolve without causing lasting damage.
Worldwide, Shigella is a much bigger problem. It is estimated to cause up to 165 million cases of disease and 600,000 deaths each year, primarily in children under the age of five in developing nations. To add to the challenge, there are new, antibiotic-resistant strains of Shigella emerging that are much more difficult to treat.
Gene Kinney, PhD, president and CEO of Prothena, a global biotechnology company, published a great article in Xconomy earlier this year about the importance of communicating science.
He says researchers need be strategic about how they talk about their work in order to enhance the public’s understanding of science and its impact on society. Using jargon-free language and developing a compelling narrative can help engage an audience and explain the science.
But Kinney acknowledges this is easier said than done. A little thing called the “curse of knowledge” can hurt a scientist’s ability to communicate with those who don’t share their baseline of expertise. Researchers need to cope with the curse and understand that buzzwords within their given field like “novel target” and “in vitro” hold little to no meaning to outsiders. Kinney emphasizes the importance of overcoming this bias and shifting assumptions about an audience’s knowledge base in order to improve scientific literacy.
Overall, scientists must begin to see themselves not only as researchers but also as communicators.