Showing papers by "David C. Schwartz published in 1994"

A method for characterizing polymer molecules or the like

Abstract: A method for observation and determination of the size of individual molecules and determination of the weight distribution of a poly disperse comprises: placing a molecule in a medium, subjecting the molecule to an external force, causing conformational/positional changes, and measuring these changes. Preferred ways to measure conformational/positional changes include: (1) determining the rate at which a deformable molecule after termination of the external force, (2) determining the reorientation rate of a molecule when the direction of the external force is changed, (3) determining the rotation rate of a molecule, (4) measuring the length of a molecule, particularly when it is partially stretched, or (5) measuring of the molecule. Measurements involve the use of a light microscope connected to an image processor or a microscope combined with a spectroscopic device.

Absence of Recoverable Infectious Virus and Unique Immune Responses in an Asymptomatic HIV+ Long-Term Survivor

Abstract: We have studied a woman with transfusion-acquired HIV who appears to have contained infectious virus to consistently undetectable levels over a 13-year period without antiviral treatment. She received the infected transfusion for intra- and postpartum blood loss immediately after delivery of her second child in 1981. She had no acute febrile syndrome and has never had HIV-associated clinical signs or symptoms in the 13 years since infection. She was first tested and found positive for HIV antibodies in 1985, and the infected blood donor was diagnosed with AIDS in 1986 and died of AIDS-related complications in 1989. Two other recipients of packed erythrocytes from this donor (in 1980 and 1982) also became infected and were subsequently diagnosed with AIDS. Between January 1986 and April 1994, in the setting of continuous and unambiguous Western blot HIV-specific antibodies and intermittently positive low-level HIV DNA signal after polymerase chain reaction (PCR) amplification, more than 30 separate cell cocultures performed in several independent laboratories failed to yield evidence of infectious virus, despite special efforts to induce and detect HIV replication. Immunologically, a strong in vitro proliferative response to HIV envelope proteins also distinguished this subject from other asymptomatic HIV+ individuals.