Human immunodeficiency virus/acquired immunodeficiency syndrome in pregnant women.

A pregnant woman experiences selective immunosuppression as a physiologic response to the presence of a genetically heterologous fetus. Case reports early in the acquired immunodeficiency syndrome (AIDS) epidemic suggested that adverse human immunodeficiency virus (HIV)-related clinical outcomes might be causally associated with pregnancy. A review of relevant published data indicates that: (1) Adverse clinical outcomes of pregnancy are common among HIV-infected pregnant women, but no studies to date have fully disentangled the many confounding factors. (2) HIV-related complications are common in pregnancy only among immunosuppressed (< 300 CD4+ cells/mm3) women. (3) The distinct effect of pregnancy on the expression of HIV infection cannot be evaluated in the absence of appropriately controlled observations. (4) Cofactors for perinatal transmission are poorly understood. (5) Research into the motives for reproductive decisions and behaviors is of critical importance for improving our health education and outreach efforts for high-risk women. (6) Adequate clinical treatment and prophylactic health care services must be made easily accessible and available to women at high risk of HIV disease. (7) Treatment with available antiviral and anti-Pneumocystis drugs is advisable for HIV-infected pregnant women with fewer than 300 to 350 CD4+ cells/mm3, though data to definitively guide therapeutic decision making are not available. (8) Large multicenter studies are needed to recruit patients and to retain them in sufficient numbers, allowing for better evaluation of the many variables determining clinical outcomes for HIV-infected mothers and their infants. The natural history of HIV in pregnant women must be studied to facilitate clinical decision making, and to design and implement interventions, including prevention (behavior change, vaccines) and treatment (chemotherapy, immunotherapy).

The Use of Synchrotron Radiation as an Absolute Source of VUV Radiation.

Synchrotron radiation has been used as a standard source to calibrate spectrographic instruments at the National Bureau of Standards (NBS). Conceptually it is straightforward to apply the calculable continuum distribution of synchrotron radiation to problems requiring a source of known irradiance if the electron energy, the radius of the electron orbit, and the beam current are known. In practice many factors affect the accuracy of such a calibration, such as temporal and spatial variations in the electron beam, uncertainties in the orbital radius and maximum energy of the orbiting electron beam. These sources of error are discussed and the method of calibration on SURF-I is specified. A storage ring synchrotron radiation facility (SURF-II) is now operational at NBS. The calibration techniques developed for SURF-I are applied to SURF-II with anticipated improvements in calibration accuracy. For SURF-I the incident flux was determined with an accuracy of 15 percent while for SURF-II we anticipate accuracies of about 7 percent.