Relationships between elastic anisotropy and thermal expansion in A2Mo3O12 materials.

We report calculated elastic tensors, axial Grüneisen parameters, and thermal stress distributions in Al2Mo3O12, ZrMgMo3O12, Sc2Mo3O12, and Y2Mo3O12, a series of isomorphic materials for which the coefficients of thermal expansion range from low-positive to negative. Thermal stress in polycrystalline materials arises from interactions between thermal expansion and mechanical properties, and both can be highly anisotropic. Thermal expansion anisotropy was found to be correlated with elastic anisotropy: axes with negative thermal expansion were less compliant. Calculations of axial Grüneisen parameters revealed that the thermal expansion anisotropy in these materials is in part due to the Poisson effect. Models of thermal stress due to thermal expansion anisotropy in polycrystals following cooling showed thermal stresses of sufficient magnitude to cause microcracking in all cases. The thermal expansion anisotropy was found to couple to elastic anisotropy, decreasing the bulk coefficient of thermal expansion and leading to lognormal extremes of the thermal stress distributions.

Transmission of Chlamydia trachomatis and Neisseria gonorrhoeae among men with urethritis and their female sex partners.

Transmission of Chlamydia trachomatis and Neisseria gonorrhoeae among infected men and their female sex partners was examined using a design enhancing the likelihood that spread was directed from men to women. Chlamydia culture-negative specimens were examined using DNA amplification tests. Infection rates in women exposed to male sex partners with Chlamydia only were 65% (20/31) and with gonorrhea only were 73% (33/45). Infection of women by either agent was not influenced by the number of sexual exposures to or coinfection in men. There was a 98% (40/41) concordance of N. gonorrhoeae isolates among partners by auxotype and serovar. Chlamydia isolates were serotyped using ELISA and immunofluorescence testing and confirmed by nested polymerase chain reaction: 50% (6/12) of men and 57% (8/14) of women yielded mixed serovars. Sixty-four percent of pairs (9/14) were infected with identical serovars and an additional 28% shared at least one serovar. Multiple serovars of C. trachomatis, but not of N. gonorrhoeae, were common in sex partners and exchanged frequently.

Oral contraception and the recognition of endometritis.

OBJECTIVE: Oral contraceptive use has been associated with a lower risk of symptomatic pelvic inflammatory disease but a higher risk of chlamydial cervicitis. To explain these seemingly contradictory findings, we asked whether oral contraceptive use was more common among women with unrecognized endometritis than among women with recognized endometritis. STUDY DESIGN: A multicenter case-control study was performed. Women without signs of pelvic inflammatory disease were ascertained through contact tracing of partners with sexually transmitted diseases or through presentation with cervicitis. Women with symptomatic pelvic inflammatory disease met a set of standard clinical criteria. We compared the 43 cases without signs of pelvic inflammatory disease but with endometritis ("unrecognized endometritis") with the 111 controls with recognized pelvic inflammatory disease and endometritis ("recognized endometritis"). RESULTS: Women with unrecognized endometritis were 4.3 times (95% confidence interval 1.6 to 11.7) more likely than women with recognized endometritis to use oral contraceptives. CONCLUSION: Future studies need to fully characterize the risks and benefits of oral contraceptives in relation to sexually transmitted diseases.

Seroprevalence of human immunodeficiency virus in parturients at Boston City Hospital: implications for public health and obstetric practice.

OBJECTIVE: We measured the seroprevalence of human immunodeficiency virus in women seeking reproductive services. STUDY DESIGN: Demographic and risk behavior data from women were linked anonymously to human immunodeficiency virus antibody results. RESULTS: The overall human immunodeficiency virus seropositivity rate of cord blood was 22 per 1000. Crude seroprevalence rates were higher for black women versus white women (25/1000 vs 22/1000) but lower for black Americans versus white Americans (21/1000 vs 29/1000). Human immunodeficiency virus infection was significantly higher for those women who acknowledge intravenous drug use (odds ratio 12.9, 95% confidence interval 7.3 to 22.7), were born in Haiti (odds ratio 2.6, 95% confidence interval 1.6 to 4.1), lacked prenatal care (odds ratio 2.2, 95% confidence interval 1.1 to 4.2), or received prenatal care at the hospital clinic versus a neighborhood health center (odds ratio 3.0, 95% confidence interval 1.7 to 5.3). The seroprevalence rates were 18/1000 for women seeking abortion and 16/1000 for women seeking family-planning services. CONCLUSION: Intravenous drug use and country of origin are major risk factors for human immunodeficiency virus infection in women, which may explain differences in seroprevalence rates in various racial or ethnic groups. Hospital-specific data on human immunodeficiency virus infection may be useful for monitoring the epidemic and allocating resources for education, counseling, testing, and prevention.

Human immunodeficiency virus (HIV) infection of the uterine cervix.

Human immunodeficiency virus (HIV) has been detected in cervical secretions from HIV-infected women. We report the isolation of HIV from four cervical biopsy specimens. Cervicitis was shown by immunohistochemical staining in cervical biopsy specimens from four HIV-seropositive women; cervicitis was not found in cervical biopsy specimens from four HIV-seronegative women. We found HIV antigens in monocyte-macrophages and endothelial cells within the submucosa of three of these cervices by specific immunohistochemical staining. Small numbers of HIV-infected cells resembling lymphocytes also were found in the cervical mucosa. The virus was not shown by culture or immunohistochemistry in cervical biopsy specimens from the four HIV-seronegative women. These findings suggest that HIV enters cervical secretions from selected infected cell populations within the cervical tissue. The HIV-infected cells in cervical tissue may be involved in transmission of HIV by heterosexual contact and to neonates born to HIV-infected women.