順天堂大学
医学部 英語
2024年度 解答・解説

Last year, a growing number of hospitals began to hand out wearable devices to patients who had been sent home after heart surgery. We spoke to two physicians about what these devices can and cannot do. Dr. Naomi Calder is a cardiologist, and Dr. Idris Okafor works in primary care.

Calder: "The strength of a wearable is that it is always on. A clinic visit gives me one snapshot every few months, but a watch records thousands of heartbeats a day. When the rhythm changes, the device detects it and sends an alert to our team, sometimes before the patient feels anything." She is quick to add that the technology is not magic. "Our staff must still be meticulous about checking each alert, because a large share of them turn out to be false alarms."

Okafor sees a different challenge. "My older patients are often reluctant to wear anything that tracks them. They worry about who will see their data," he said. "We spend more time explaining privacy than explaining the heart." To address this, his clinic created a one-page guide in plain language, and nurses sit with each patient to set up the device.

Both doctors agree that the most important change is cultural rather than technical. When data arrive daily, doctors can step in early, and small problems are less likely to grow into emergencies. "In the past we waited for patients to come to us," Calder said. "Now we can reach out first." Okafor warned, however, that outreach has a cost. "If every alert leads to a phone call, the staff will burn out. We need software that can sort the signals so that humans see only the ones that matter." Such a tool, he said, could also curb unnecessary hospital visits and save money.

Asked about the gap between rich and poor patients, Calder admitted that it worries her. "A device that costs a month's rent will never reach the people who need it most." Okafor hopes that insurers will one day pay for devices the way they pay for medication. Until then, both doctors insist that the patient's outcome, not the number of gadgets sold, should be the measure of success.

①Far below the waves, on plains of mud and rock that no sunlight has ever touched, lie millions of metal-rich lumps called nodules. For decades they sat unnoticed. Now, as the demand for batteries grows, companies are eager to bring them up. But a simple question stands in the way: who has the right to take them?

②The answer begins with a treaty. In 1982, the United Nations Convention on the Law of the Sea (UNCLOS) divided the oceans into zones. Within 200 nautical miles of a coast, a country may use the water and the seabed for its own purposes. Beyond that lies the high seas, and the seabed there is described as the "common heritage of mankind."

③To manage this shared seabed, the convention created the International Seabed Authority (ISA), based in Jamaica. No company can work in the area without a contract from the ISA, and any profit is supposed to be shared with the world, including countries without a coastline. "It was a bold idea," said Dr. Lena Marlowe, an ocean-law scholar at the University of Brightwell. "It still is."

④But the system has gaps. The ISA has issued many licenses for exploration, yet it has not finished the detailed rules for actual commercial mining. In 2021, a small island nation in the Pacific started a two-year clock that obliges the ISA to consider any mining application, whether or not the rules are ready.

⑤Some countries argue that mining should be paused until its effects on marine life are better understood. Scientists warn that the deep sea is home to slow-growing animals, and that scars left on the seabed may take centuries to heal. "We are moving faster than our knowledge," Marlowe said.

⑥Others take a different view. They say that the minerals are needed to build electric cars and wind turbines, and that mining the seabed may cause less harm than digging up forests on land. The United States, which has not ratified UNCLOS, has also suggested that it could license its own companies under domestic law, a step many lawyers consider risky.

⑦Unlike a flag planted on bare ground, a mining ship leaves physical marks, so disputes are unlikely to stay theoretical. A single license could affect fisheries thousands of kilometres away, and it is unclear who would pay if something went wrong.

⑧"This is not a problem for the distant future," Marlowe said. "The ships are being built now." Whatever the ISA decides in the coming years, the outcome will show whether the idea of a shared ocean can survive contact with commercial interest.

①A crow does not forget a face. In a long-running study led by Dr. Hiro Tanabe of the University of Westbury, researchers wore rubber masks while catching and tagging wild crows in a city park. Years later, when the same masks reappeared, crows that had never been caught scolded the wearer loudly, as if they too knew who the enemy was.

②Tanabe describes the result as "unsettling and wonderful at once." His team recorded the birds' reactions for six years. Crows that had been caught remembered the mask for at least five years, and the number of birds that scolded it kept growing. Many of the angry crows were young birds that had not even hatched at the time of the capture.

③How did the news spread? The scientists believe there are two routes. Young crows learn by watching their parents react, while others pick up the alarm calls of their neighbors and link them to the mask they see. Brain scans of crows shown the dangerous mask showed more activity in regions linked to fear and memory than scans of birds shown a neutral mask.

④The findings may help explain why crows live so successfully in cities. A species that can pass on knowledge about danger can adapt quickly when new hazards, such as cars or poison, appear.

⑤Not everyone is convinced. Dr. Maria Quint, a behavior specialist at the Ardent Institute, praised the study but cautioned against reading too much into it. "Scolding a mask is not the same as holding a grudge," she said. "A bird may simply react to anything that looks like a threat." She also noted that the study followed crows in one city, so the result may not apply elsewhere.

⑥Tanabe agrees that more work is needed. His next step is to test whether crows can recognize human faces in photographs, which would show that they do not depend on a single feature such as a mask. If they can, he says, we may need to rethink how much information birds take from the people around them.

①Axolotls, sometimes called "walking fish," are small salamanders that can regrow a lost leg, a damaged heart, and even parts of their brain. Researchers at the Northfield Institute have now produced the most complete map yet of the axolotl genome, shedding light on how the animal performs such astonishing feats.

②The task was far from easy. The axolotl genome is about ten times larger than the human one, and much of it is made of repeating sequences that confuse sequencing machines. Earlier attempts left many gaps. "It was like assembling a puzzle with thousands of nearly identical pieces," said geneticist Dr. Samira Voss, who led the project.

③To solve the problem, the team combined two technologies: one that reads long stretches of DNA, and another that reads short stretches with high accuracy. The result is a genome with far fewer gaps than any earlier version. Axolotls have long fascinated doctors. Humans heal wounds by forming scars, while an axolotl simply regrows what it has lost, with bones, muscles, and nerves all in the right place.

④Scientists hope that understanding this process could one day help patients with spinal injuries or damaged hearts. A few months ago, another group reported that axolotl cells placed in a mouse kept some of their ability to form new tissue. Such results are encouraging, though they remain far from clinical use.

⑤Many scientists had assumed that regeneration must depend on a small set of genes found only in salamanders. The new genome challenges this view. Voss's team found that most of the genes involved in regrowth also exist in humans and other animals.

⑥What differs is how those genes are switched on. After an injury, the axolotl activates a group of them in a precise order within hours, something mammals do not do. The team identified several stretches of DNA that act like switches, and showed that some of them become active only near wounds.

⑦In an experiment, the researchers removed one of these switches from young axolotls. The animals grew normally, but their ability to regrow a limb was reduced by about half. "The switch is helpful, but it is not the whole story," Voss said.

⑧The study also found that axolotls carry extra copies of genes that repair damaged DNA, which may protect cells during rapid growth. Whether these copies contribute to regeneration is not yet known.

⑨Voss is cautious about the prospects for people. "We will not be regrowing human arms any time soon," she said. "But if we can learn when to turn the switches on, we may be able to help the body heal better than it does now." For now, the little salamander has again shown that nature still has many lessons to teach us.