雅思阅读 193: Beyond the Machine — The Long Search for a Wearable Kidney（机器之外：可穿戴肾脏的漫长求索）

改编自 Rabb, Lee & Parikh, Journal of Clinical Investigation（2022年）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://www.jci.org/articles/view/159308

Reading Passage

A. For the tens of millions of people who live with failing kidneys, the modern treatment is almost unchanged from the one that arrived in the 1940s. Healthy kidneys do more than cleanse blood: they balance salts and water, regulate blood pressure and clear the waste that accumulates every hour. When those organs fail, the blood fills with toxins that would quickly kill. It was against this emergency that Willem Kolff built the first workable dialysis machine in 1943, and Belding Scribner added the life-sustaining arteriovenous fistula in 1960, a surgical connection that let patients be connected repeatedly without destroying their veins. Joseph Murray performed the first successful human kidney transplant in 1954, and transplantation has remained the preferred option ever since. Yet for all the ingenuity behind these breakthroughs, conventional dialysis still rests on an awkward compromise. A patient must be tethered to a stationary machine for several hours at a time, usually three sessions a week, while blood is pumped out, cleansed and returned. Today more than 750,000 people in the United States and some 2.6 million worldwide depend on such treatment, and the global figure is projected to double by 2030. The queue for a donated organ grows longer each year, while the dialysis schedule quietly organises every other part of a patient's life around the clinic timetable.

B. This mismatch between a machine built for a clinic chair and a human life spent moving has driven engineers toward a more radical idea: a dialysis device small enough to wear. Conventional hemodialysis needs litres of cleansing fluid discarded after a single pass, which is one reason it cannot be portable. The wearable artificial kidney is a miniaturised machine that recycles its fluid through sorbent cartridges, so that the same small reservoir can cleanse blood for hours, and circulates it together with blood through a belt-like pack strapped to the body. Its most recent version weighs up to 5 kilograms and connects to the circulation through catheters, freeing the patient from the clinic room. In a human trial, volunteers tolerated the device for a full 24 hours without serious complications, and the clearance of waste products proved effective; the mean volume of excess fluid removed was about one litre, and participants also reported greater satisfaction than with conventional hemodialysis. There is, however, a catch. The study was halted before its planned end because of recurring technical faults, including unstable flow rates and bubbles of carbon dioxide forming in the circuit. Rather than disproving the concept, the episode showed how much miniaturisation still has to solve: a machine that sits on a bench can shrug off problems that become dangerous when worn against the skin.

C. A bolder variant abandons the exterior altogether. The implantable bioartificial kidney is a hybrid that joins a mechanical filter, made from a finely perforated silicon membrane, with a living bioreactor holding engineered renal tubule cells. The silicon sieve reproduces the sieving action of the glomerulus, while the cells take over the subtler work of balancing electrolytes and performing metabolic tasks that a passive filter cannot. Crucially, the device is designed to attach directly to the bloodstream and to be driven by the patient's own blood pressure, removing the need for any electric pump; filtered waste would drain straight into the bladder. Prototype cartridges have functioned inside dogs for as long as a month without clotting or external anticoagulants. The obstacles, though, are serious. A filter that clots inside the body could require repeated surgery to replace, and the engineered cells must survive the relentless shear force of circulating blood for years rather than weeks while remaining genetically stable. No such device has yet been tested in a human, and the durability of a living component sealed inside a sterile circulation for a decade is an open engineering problem.

D. Alongside these mechanical substitutes, biologists are trying to rebuild the kidney itself. A kidney-on-a-chip uses microfluidic channels to grow real tubule and glomerular cells in conditions that imitate living tissue, allowing researchers to test drug toxicity and disease in miniature; vascularised models have even reproduced the selective barrier that keeps useful proteins in the blood while letting waste through. More ambitious still is the effort to grow whole kidneys from induced pluripotent stem cells, assembling the cells into three-dimensional organoids that self-organise into recognisable structures with distinct cell types. The recent arrival of 3D bioprinting lets engineers stack these cells layer by layer with greater precision and reproducibility. Yet a humbling finding has tempered the enthusiasm: single-cell analyses reveal that even the best organoids stop maturing at a stage resembling a second-trimester fetal kidney. They can model development and injury, but they cannot yet stand in for an adult organ — a gap that sets the research agenda for the next decade.

E. The most controversial route to closing the organ gap is xenotransplantation — growing kidneys inside pigs. In the United States alone, over 90,000 patients wait for a kidney each year, while only around 20,000 to 25,000 transplants take place. Pigs are attractive donors because their organs are roughly the size of a human's, but their tissues carry sugar markers that trigger immediate rejection; those genes have been edited out, along with insertion of protective human genes. In brain-dead recipient trials, such a pig kidney — carrying ten genetic modifications — produced urine for 72 hours, although it failed to achieve full waste clearance and showed signs of blood-vessel injury. If the technical problems can be solved, the ethical, social and religious questions remain, along with the risk of unknown viruses crossing the species barrier. What unites these very different approaches — the belt, the implant, the chip, the organoid and the pig — is a shared dissatisfaction with a treatment that, for all its life-saving power, still asks patients to live their lives around the machine rather than the machine around their lives.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. A device that lives beneath the skin ii. How Kolff built the first clinic iii. Shrinking the machine to a belt iv. Growing kidneys in a dish — and their limits v. Why conventional dialysis was invented vi. Borrowing organs from another species vii. The rising cost of dialysis

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. What is the main drawback of conventional dialysis according to the first paragraph? A. It cannot remove waste products from the blood. B. It ties patients to a fixed schedule and location. C. It was abandoned after the 1940s. D. It works only for children.

6. Why was the wearable kidney trial stopped early? A. Volunteers refused to continue wearing the belt. B. Serious complications arose within hours. C. Technical problems such as unstable flow and gas bubbles recurred. D. The device proved unable to clear any waste.

7. What is distinctive about how the implantable bioartificial kidney is powered? A. It uses a replaceable battery pack. B. It relies on the patient's own blood pressure. C. It is driven by an external electrical pump. D. It runs on solar energy.

8. What limitation did single-cell analyses reveal about stem-cell organoids? A. They grow more quickly than real kidneys. B. They fail to mature beyond a fetal developmental stage. C. They cannot be grown in the laboratory at all. D. They develop only adult kidney tissue.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. The number of people worldwide receiving kidney replacement treatment is expected to double by 2030.
10. In the wearable kidney trial, participants reported lower satisfaction than with conventional hemodialysis.
11. The implantable bioartificial kidney requires an external electric pump to function.
12. The pig kidney used in the decedent trial produced urine for 72 hours.
13. Most patients prefer peritoneal dialysis over hemodialysis.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

The wearable artificial kidney weighs up to five kilograms and connects to the blood through (14) __________, while the implantable version uses a perforated (15) __________ membrane to mimic the kidney's filtration.

答案与解析

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