Dear Doctor: What on earth is a “gutoscopy”? We saw it on the news -- something about a pill that goes in one end and comes out the other, but it sounded more like science fiction than anything real.

Dear Reader: Your question brings us to the brave new world of what are sometimes referred to as “smart pills.” These are tiny devices, small enough to be swallowed, that perform a range of functions as they move along the gastrointestinal tract. This can include the precision delivery of medication, the collection of different types of data, and keeping track of whether or not someone is taking a prescription as needed.

Certain types of smart pills are equipped with biosensors, pH and chemical sensors, or imaging capabilities. Classified as ingestible sensors, they can be used to collect information such as pressure readings, pH and temperature data. The data they gather can shed light on the workings of the stomach, small bowel and colon. Rather than an invasive procedure that requires surgery or an instrument threaded through a catheter, the patient swallows a capsule that contains the miniature sensor. The device then transmits its findings to a computer.

Some types of smart pills are engineered to collect samples from inside the body for study and analysis. That’s the case with the “gutoscopy” device you’re referring to in your question. Developed several years ago by researchers at Purdue University, the team published a paper about its findings earlier this year. Their goal was to devise a noninvasive method to learn more about the billions of microscopic organisms that live within the human gut.

Research continues to link the workings of the gut microbiome to an ever-expanding array of biological functions and health conditions. This includes obesity, diabetes, mood, digestive disorders, cardiovascular health and certain cancers. The composition of the gut microbiome has also been linked to various neurological diseases, including Parkinson’s disease, multiple sclerosis, autism spectrum disorder and Alzheimer’s disease.

The “gutoscopy” capsule, which is still in the research phase, is made of nontoxic 3D-printed resin. It’s formulated to dissolve at a specific pH within the gut. This allows the release of a “thirsty” gel, similar to that used in moisture-absorbing pads and diapers. The hydrogel collects gut bacteria from the fluid of the intestine. The capsule is designed to travel the length of the bowel, carried along by the natural wavelike contractions of the digestive process. It collects samples as it goes, until a change in pressure forces the capsule to close. The device passes from the body in a bowel movement. Researchers can then open the capsule, collect the gel and analyze the array of gut flora that it contains.

Unlike existing diagnostic tests, such as a colonoscopy or an endoscopy, this new capsule can travel the entire length of the gut, and it wouldn’t have to be administered in a clinical setting. The goal is to learn more about the diversity of microorganisms living within the gut. That information can help researchers better understand disease processes, and craft medications and therapies.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I was having a panic attack and thought I might faint. My dad had me breathe into a paper bag, and it helped me calm down. I’ve only ever seen that on TV. Why did it work? Was it because I ended up doing deep breathing?

Dear Reader: It’s interesting how, when a TV character hyperventilates, someone just happens to have a brown paper lunch bag for them to breathe into. And while the rhythmic nature of that breathing may contribute to calming down the person, the actual theory behind the maneuver is rooted in biochemistry. To understand why, let’s start with the anxiety attack. Often referred to a panic attack, it’s the sudden onset of symptoms associated with fear, despite the absence of genuine peril. Among the many unpleasant and unsettling symptoms of a panic attack is the rapid and uncontrolled breathing known as hyperventilating. When this happens, it quickly causes the concentrations of oxygen and carbon dioxide in the blood to get out of balance.

Unlike in controlled breathing, which allows the respiratory system to take in oxygen and expel carbon dioxide in optimal amounts, hyperventilation causes a surplus of oxygen and a deficit of carbon dioxide, also known as C02. Since C02 is a metabolic byproduct -- sometimes it’s referred to as a waste product -- that may not seem like a bad thing. Too much C02 dissolved in the blood can cause symptoms that range from dizziness, drowsiness, headache, confusion and shortness of breath to heart arrhythmias, seizures and loss of consciousness. However, too little C02 is also a problem.

Our blood has an optimal pH, which is maintained by a specific ratio of dissolved oxygen and carbon dioxide. When you hyperventilate, that ratio is disturbed. Too much oxygen causes the pH of the blood to rise and become too alkaline. This is known as respiratory alkalosis. Symptoms can include anxiety, dizziness, dry mouth, tingling in the fingers and arms, chest pain or tremors. In fact, some research has suggested a link between panic disorders and poor regulation of blood pH.

All of which brings us back to the person now breathing into a paper bag. With every exhale, they are filling the bag with C02. With every inhale, they make that C02 available to their over-oxygenated blood. When you inhale your own exhaled air, it’s known as rebreathing. The theory is that, after a moment or two, rebreathing will begin to stabilize blood pH and perhaps ease your symptoms.

However, it’s important to note that rebreathing is unsafe for certain people, particularly those with heart or lung problems. Having too little oxygen in the blood, which is known as hypoxemia, can share symptoms with an anxiety attack. These include shortness of breath, dizziness and rapid breathing. If someone experiencing hypoxemia practices rebreathing with a paper bag, they’re not only making their immediate condition worse, they’re putting themselves in danger. The bottom line is, unless you know beyond a shadow of a doubt that you’re hyperventilating due to an anxiety attack, leave the paper bag maneuver to the TV writers.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Hello again, dear readers, and welcome to the late-summer edition of the letters column. Along with so many of you, we’re facing record-breaking heat, high humidity and a few natural disasters. All the more reason to seek refuge in our ongoing chat about health and medicine.

-- Many of you continue to have questions about the novel coronavirus.

“If a sneeze can spread the virus, can exhaling also spread the virus?” a reader asked. “So many times I see people with their mask under their nose and want to say something, but do not because I do not want to get into a fight.”

It’s important to remember that we’re still in the earliest stages of learning about the novel coronavirus. Emerging research suggests that, in addition to respiratory droplets from a cough or a sneeze, the virus may also be present in the microdroplets expelled during breathing and speech. What isn’t yet clear is whether or not these are a major source of infection. We will keep an eye on that research and update any new findings.

When it comes to wearing a mask, you’re correct on two points. First, the mask should indeed cover both the nose and the mouth. It should also have a snug fit around the perimeter. And we think you’re wise not to comment on how someone else wears his or her mask. Unfortunately, this practice, which we engage in to protect each other, has become a hot-button issue. Better to move at least 6 feet away from that individual and go about your day.

-- And speaking of transmission: “Why aren’t belching and expectorating mentioned as vehicles for spreading the coronavirus?” a reader asked. “If I can smell the belched air, surely it’s possible for the virus to be suspended in it.” The act of spitting or emitting a large and sustained belch can send respiratory droplets into the air. Although it’s possible that these can spread the virus, they are not known to be a major means of transmission.

-- A reader who recently survived COVID-19 wrote to ask about the likelihood of becoming infected again. “I contracted COVID-19 on July 1, became ill and tested negative on July 21,” he wrote. “My symptoms were coughing, muscle aches and fatigue. Pneumonia ensued for two weeks. I then tested positive for antibodies on July 23. How concerned should I be about contracting it again?”

Unfortunately, the answer isn’t clear yet. Researchers in Hong Kong recently identified what appears to be the first known case of reinfection 4 1/2 months after a patient’s initial illness. This reinfection, with a slightly different strain of the virus, occurred when the young man traveled to Spain. Genomic testing revealed differences in the two variants of the virus, which researchers say proves this is indeed a reinfection rather than prolonged viral shedding. The young man had no symptoms, and researchers believe existing antibodies helped his immune system fight off the second infection. Still, the wisest course is to continue practicing all precautions to protect yourself and those around you.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)