Biden Asked to Raise Case of Jailed Nobel Laureate and Wife A group of human rights organizations has issued an open letter calling on Vice President Joseph R. Biden Jr. to press Chinese officials on the plight of two of the country's most prominent dissidents, Liu Xiaobo, the imprisoned Nobel Laureate, and his wife, Liu Xia, who is under house arrest and said to be suffering from severe depression. The letter, released by Amnesty International, Human Rights Watch and the PEN American Center on the eve of Mr. Biden's visit to China, urges him to reaffirm America's commitment to human rights by asking Beijing to release Mr. Liu and end the harassment of his wife. Mr. Liu is serving an 11-year sentence on subversion charges, and his wife, a poet and artist, has been held incommunicado for more than three years without being charged. The three groups write: We understand that there are a plethora of important issues that you will be discussing when you are in Beijing, but we hope that this will be one of them. Please continue to raise Liu Xiaobo's case at every available opportunity, and demand that authorities end all forms of repression and intimidation of his family, including freeing Liu Xia from extralegal house arrest. Advocates hope Mr. Biden's visit will provide an opportunity to highlight deteriorating human rights conditions in China at a time when many world leaders, mindful of the country's growing economic clout and worried about incurring Beijing's wrath, have softened their criticism of the government's persecution of rights activists, as well as those who advocate for political reform and greater autonomy for China's ethnic minorities. Critics in recent days have expressed disappointment over what they describe as a decision by Prime Minister David Cameron of Britain to play down human rights concerns during a trade mission to China this week. It was Mr. Cameron's first visit to China since meeting with the Dalai Lama, the Tibetan spiritual leader, in London last year, angering Chinese officials and causing a chill in diplomatic relations. The plight of Mr. Liu, an essayist jailed in 2009 for organizing a petition demanding free elections, is well known outside of China. But the predicament of his wife has received less attention, in part because she has been essentially locked inside the couple's Beijing apartment since her husband won the Nobel Peace Prize in 2010. In recent days, Ms. Liu's friends have helped turn a spotlight on her plight by releasing letters that reveal the suffering she has endured under a draconian form of house arrest. On Tuesday, a family friend, Zeng Jinyan, quoted Ms. Liu making three requests: I request the right to consult a doctor freely. I request that Liu Xiaobo and I are allowed our rights to read correspondence we write to each other. I request the right to work and receive an income. Ms. Zeng, herself the wife of another well-known dissident, Hu Jia, said Ms. Liu was seeking medical treatment for heart disease and for the depression she blames on her mistreatment by the authorities. She said Ms. Liu also expressed fear that Chinese doctors, under pressure from the authorities, might use her mental condition to confine her to a psychiatric hospital. In an interview from Hong Kong, where she now lives, Ms. Zeng would not disclose how she had communicated with Ms. Liu. But she said Ms. Liu was buckling under the isolation imposed by public security agents and by the recent conviction of her brother, Liu Hui, who was sentenced to 11 years in prison in June on fraud charges that many legal experts say were politically motivated. The manager of a real estate company, Mr. Liu had provided financial support to his sister and other relatives, and friends say his imprisonment has left the family nearly destitute. "This has added to the family pressure on Liu Xia, and she hopes to earn an income to support the family and especially to meet the costs of Liu Hui's son's schooling," Ms. Zeng wrote on her blog. One friend said Ms. Liu hoped she might be able to sell some of her paintings and photographs. Ms. Zeng, who spent several years under house arrest during her husband's detention, said the isolation endured by Ms. Liu could be debilitating. "Any attempt to live a normal life is destroyed," she said, recounting how the police refused her requests to walk outdoors with her newborn child. They told me I could get fresh air from the window. In a separate letter made public last week, Ms. Liu provided a heart-rending glimpse of her lonely existence, one relieved by reading and occasional visits from family members. Mo Shaoping, a lawyer who defended Mr. Liu at his trial and who filed an appeal last month, said he hoped Mr. Biden would champion the couple's cause during his meeting on Wednesday with President Xi Jinping, who has described judicial fairness as a lynchpin in the nation's quest for domestic stability. "This is about Liu Xia and her right of basic survival," Mr. Mo said. They don't have an iota of legal justification for what they are doing to her.