Exploring pathways to successful aging among older black lesbians and sexual minority women: A focus on life satisfaction and intersectional factors

PURPOSE

Satisfaction with life is a core aspect of successful aging, which is influenced by a broad range of factors, including health, socioeconomic status, and social relationships. Black lesbians experience various social challenges, including racism, sexism, ageism, and heterosexualism, that may present as deterrents to aging successfully. To develop better policies and programs in support of successful aging among all adults, an understanding of the unique components associated with their intersecting identities must be explored. This study was carried out to gain a better understanding of how Black lesbians and other Black sexual minority women (BSMW) view successful aging within the context of life satisfaction.

METHODS

Inferential statistics were used to determine relationships between satisfaction with life (SWLS-3) and selected independent variables. Backward stepwise regression was conducted to ascertain significant relationships of the study outcome variable.

RESULTS

The respondents were 118 Black lesbians and other BSMW aged 50 and above. Independent t-tests showed that those living with a partner had a significantly higher SWLS-3. Backwards stepwise regression indicated the predictor variables for higher rates of SWLS-3 to be harmony in life, annual household income, and provider sensitivity/cultural competence to their patient being Black.

CONCLUSION

This study provides insight on factors increasing and diminishing satisfaction with life for aging Black lesbians and other BSMW. Future research should replicate this study with a more diverse and nationally representative sample, especially given the study limitations of having recruited a highly educated sample during a global pandemic.

Caregiving Among Older Black Same-Gender-Loving Women During the COVID-19 Pandemic: Findings From Qualitative Research

BACKGROUND AND OBJECTIVES

Few data on caregiving during the coronavirus disease 2019 pandemic use an intersectional lens to attend to how multiple social categories, such as gender, age, race, and sexual orientation, shape caregiving experiences. This analysis sought to explore caregiving experiences of aging Black same-gender-loving women.

RESEARCH DESIGN AND METHODS

Sixteen focus groups were conducted with 4-8 participants each (N = 102) from across the United States. Audio-recorded discussions lasted for approximately 90 min and were transcribed verbatim. Two analysts coded transcripts for discussions related to caregiving and used content analysis to identify themes.

RESULTS

Participants engaged in caregiving for children, parents, family, friends, and neighbors. They provided physical, economical, instrumental, and/or secondary caregiving; and sometimes received care themselves. The pandemic heavily affected their stress level and mental health as well as their intimate partner relationships. Discussions mostly offered descriptions of increased caregiving difficulty caused by the pandemic. However, a few participants identified ways the pandemic made caregiving easier; changed caregiving without making it easier or harder; or thwarted their ability to provide care.

DISCUSSION AND IMPLICATIONS

Older Black same-gender-loving women described some pandemic caregiving experiences that diverged from the existing literature, demonstrating the importance of considering how gender, race, age, and sexual orientation affect caregiving experiences during a pandemic fraught with health inequities. Ensuring the multiply marginalized caregivers have access to the practical and emotional support they need is critical for advancing health equity and preparing for future pandemics.

Caregiving During the COVID-19 Pandemic: A Cross-Sectional Study with Older Cisgender Sexual Minority Women in the United States

Purpose: This study describes prevalence of caregiving before and after the onset of the COVID-19 pandemic among racially diverse older cisgender sexual minority women, examines factors associated with caregiving, and assesses relationships between caregiving and health. Methods: A convenience sample of participants aged ≥50 years completed self-administered online surveys assessing sociodemographic characteristics, caregiver status, self-rated health, and depressive symptoms. Bivariate statistics compared response variables by race, caregiver status, and timing of caregiving relative to the pandemic. Results: Of 365 participants, 82.7% identified as lesbian or gay and 41.1% as Black/African American; 40% were caregivers before (n = 32), during (n = 34), or both before and during (n = 80) the pandemic. A greater proportion of caregivers lived with a partner (45.9% vs. 35.6%, p = 0.06), were unemployed (37.7% vs. 29.7%, p = 0.07), and had high school or lower education (11.6% vs. 5%, p = 0.09). No differences were found in self-rated health by caregiver status; however, a higher proportion of Black (vs. White) caregivers reported good to excellent physical health (77.9% vs. 62.9%, p = 0.05). Caregivers more frequently reported depressive symptoms (28.1% vs. 17.8%, p = 0.03). Caregivers both before and during the pandemic had lower educational attainment than those who provided care only before or only during the pandemic (p = 0.04). Conclusion: Caregiving was common among older sexual minority women during the pandemic and experiences varied by race and other social factors. Consideration of these intersecting experiences is important for fully understanding caregiver experiences during COVID-19. Overall, caregiving was associated with depressive symptoms, underscoring the importance of psychosocial support for all caregivers.

Engaging Black sexual minority women in breast cancer research: Lessons in community partnerships

BACKGROUND

Black sexual minority women (BSMW) face significant breast cancer health inequities and are underrepresented in health research because of historical and present-day exclusion. However, there exists no peer-reviewed literature on best practices for the inclusion of BSMW in cancer research. "Our Breast Health: The Access Project" was a national primary data collection study in June 2018 through October 2019 that aimed to identify facilitators and barriers to breast cancer care among BSMW, and that successfully recruited the highest number of BSMW for any national breast cancer screening study at the time of its publication.

METHODS

The present analysis highlights best practices for reaching BSMW by examining by how effective various recruitment sources were at recruiting BSMW. Recruitment partners were grouped into several categories: (1) cancer focused, (2) Black women or sexual minority women focused, (3) BSMW focused, (4) social media, and (5) other. Then logistic regression was used to estimate the odds that a particular recruitment source category could recruit BSMW compared with other categories.

RESULTS

Partnerships with community-based organizations led by and intended for BSMW were the most successful at recruiting BSMW, demonstrating the importance of an intersectional approach to recruitment. Community-based organizations focused on BSMW specifically were 26 times more successful in recruiting BSMW to the study compared with recruiting Black women who were not sexual minorities (odds ratio, 26.43 [95% CI, 7.50-93.10]).

CONCLUSIONS

Successful recruitment enables breast cancer research grounded in the perspectives of BSMW, which can generate key findings that have the potential to remedy longstanding health inequities for this population.

OLDER BLACK LESBIANS' NEEDS AND EXPECTATIONS IN RELATION TO LONG-TERM CARE FACILITY USE

The older adult sexual minority (SM) population encompasses a vast array of individuals from diverse backgrounds. However, there is a dearth of gerontological research that focuses on the experiences of SM subgroups, particularly older Black lesbians. The purpose of this study was to explore older Black lesbians’ needs and expectations in relation to the utilization of long-term care (LTC) facilities. We conducted secondary data analysis using data from 14 focus groups (n=100) that discussed health and aging with older Black lesbians. Transcriptions were analyzed in NVivo 12 using content analysis and structural coding. Three major themes were identified in relation to needs and expectations for LTC facility use: (1) consideration of or plans established to utilize a LTC facility, (2) concern for care facility environment, and (3) a desire to build one’s own community instead of LTC use. Within these themes, prominent topics included having to rely on LTC due to a lack of family or social support, the possibility of being isolated and stifling their lesbian identity and creating communities of mutual support to avoid facility-based care. These findings illustrate how older Black lesbians are planning for a potential need for LTC, their concerns about utilizing LTC, and alternative approaches to avoid LTC use. There remains a continued need for LTC communities that are inclusive and supportive of SM older adults as well as more SM-only communities where older adults can live openly and authentically.

Older Black Lesbians' Needs and Expectations in Relation to Long-Term Care Facility Use

There is a dearth of long-term care research that focuses on the expectations and experiences of older sexual minority (SM) adults. That research dwindles further when examining subgroups within that population such as older Black lesbians. The purpose of this study was to explore older Black lesbians' needs and expectations in relation to the utilization of long-term care (LTC) facilities. We conducted secondary data analysis using data from 14 focus groups that discussed health and aging with older Black lesbians. Transcriptions were analyzed in NVivo using deductive content analysis and structural coding. Three themes were identified in relation to needs and expectations for LTC facility use: (1) consideration or established plans to utilize a LTC facility, (2) concern for care facility environment, and (3) a desire to build one's own community. These findings illustrate how older Black lesbians are planning for a potential need for LTC, their concerns about utilizing LTC, and alternative approaches to avoid LTC use. There remains a continued need for LTC communities that are inclusive and supportive of SM older adults as well as more SM-only communities where older adults can live openly and authentically.

Delays in breast cancer care by race and sexual orientation: Results from a national survey with diverse women in the United States

BACKGROUND

Despite known differences in breast cancer by both race and sexual orientation, data on the intersectional experiences of Black sexual minority women (BSMW) along the care continuum are scant. This study sought to understand delays in breast cancer care by examining the intersection of race and sexual orientation.

METHODS

This online, cross-sectional survey enrolled racially and sexually diverse women aged ≥ 35 years who had been diagnosed with breast cancer within the prior 10 years or had an abnormal screening in the prior 24 months. The authors calculated summary statistics by race/sexual orientation categories, and they conducted univariate and multivariable modeling by using multiple imputation for missing data.

RESULTS

BSMW (n = 101) had the highest prevalence of care delays with 5.17-fold increased odds of a care delay in comparison with White heterosexual women (n = 298) in multivariable models. BSMW reported higher intersectional stigma and lower social support than all other groups. In models adjusted for race, sexual orientation, and income, intersectional stigma was associated with a 2.43-fold increase in care delays, and social support was associated with a 32% decrease in the odds of a care delay.

CONCLUSIONS

Intersectional stigma may be an important driver of breast cancer inequities for BSMW. Reducing stigma and ensuring access to appropriate social support that addresses known barriers can be an important approach to reducing inequities in the breast cancer care continuum.

Beyond Black and White: race and sexual identity as contributors to healthcare system distrust after breast cancer screening among US women

OBJECTIVE

Healthcare system distrust (HCSD) has been linked to poor breast cancer outcomes. Previous HSCD analyses have focused on Black-White disparities; however, focusing only on race ignores the complex set of factors that form identity. We quantified the contributions of race and sexual minority (SM) identity to HCSD among US women who had received breast cancer screening.

METHODS

This cross-sectional study used intersectionality decomposition methods to assess the degree to which racial and SM identity contributed to disparate responses to the validated 9-item HCSD Scale. The sample included online survey participants identifying as a Black or White woman living in the US, with a self-reported abnormal breast cancer screening result in the past 24 months and/or breast cancer diagnosis since 2011.

RESULTS

Of 649 participants, 49.4% of Black SM women (n = 85) were in the highest HCSD tertile, followed by 37.4% of White SM women (n = 123), 24.4% of Black heterosexual women (n = 156), and 19% of White heterosexual women. Controlling for age, 72% of the disparity in HCSD between Black SM women and White heterosexual women was due to SM status, 23% was due to racial identity, and 3% was due to both racial and SM identity.

CONCLUSIONS

SM identity emerged as the largest driver of HCSD disparities; however, the combined racial and SM disparity persisted. Excluding sexual identity in HCSD studies may miss an important contributor. Interventions designed to increase the HCS's trustworthiness at the provider and system levels should address both racism and homophobia.

"This is some mess right here": Exploring interactions between Black sexual minority women and health care providers for breast cancer screening and care

BACKGROUND

Few studies have explored how the intersection of race and sexual identity contribute to breast cancer disparities for Black sexual minority women (SMW). Issues within patient-provider relationships, including bias, contribute to health disparities for minority groups. The authors used constructs from self-determination theory (SDT) to explore the nature of health care provider interactions in breast cancer screening and care among Black SMW.

METHODS

Participants were sampled nationally through social media, targeted emails, and referrals. Qualitative, in-depth interviews were conducted with 15 Black cisgender SMW, ages 38 to 64 years, who had a breast cancer diagnosis or recent abnormal mammogram. Interviews were conducted face-to-face or online, audio-recorded, and transcribed verbatim. Two analysts coded the interviews. Codes were analyzed across interviews to identify themes salient to SDT.

RESULTS

Themes aligned with the SDT constructs of relatedness and autonomy. Some participants discussed feeling most understood by Black and/or female providers who shared at least 1 of their identities. Feeling understood through shared identity contributed to participants feeling seen and heard by their providers. Participants who discussed negative experiences with providers believed that the provider made negative assumptions about them based on their race and/or sexual orientation.

CONCLUSIONS

When interacting with health care providers for breast cancer screening and care, Black SMW face specific challenges related to their multiply marginalized social position. Reducing health care provider bias toward Black SMW may improve patients' desires to continue in care. Providing equitable care while acknowledging and respecting women with multiply marginalized identities may improve the nature of these interactions.

Associations of social cohesion and quality of life with objective and perceived built environments: a latent profile analysis among seniors

BACKGROUND

Healthy aging requires support from local built and social environments. Using latent profile analysis, this study captured the multidimensionality of the built environment and examined relations between objective and perceived built environment profiles, neighborhood social cohesion and quality of life among seniors.

METHODS

In total, 693 participants aged 66-97 were sampled from two US locales in 2005-2008 as part of the Senior Neighborhood Quality of Life Study (SNQLS). Perceived social cohesion and quality of life were assessed using validated surveys. Six objective (geographic information system (GIS)-based) and seven perceived built environment latent profiles generated in previous SNQLS publications were used for analyses. Mixed-effects models estimated social cohesion and quality of life separately as a function of the built environment profiles.

RESULTS

More walkable and destination-rich perceived built environment profiles were associated with higher social cohesion and quality of life. Objective built environment profiles were not associated with social cohesion and only positively associated with quality of life in only one locale (Baltimore/DC).

CONCLUSIONS

Latent profile analysis offered a comprehensive approach to assessing the built environment. Seniors who perceived their neighborhoods to be highly walkable and recreationally dense experienced higher neighborhood social cohesion and quality of life, which may set the stage for healthier aging.

P1541The relation between right ventricular-pulmonary circulation coupling and aging in healthy population

Purpose

The aim of the study was to evaluate the right ventricular (RV) structure and functional adaptation to age, in particular the RV pulmonary circulation (PC) coupling and physiologic correlates.

Methods

1177 healthy subjects aged 16–100 years were enrolled. They underwent general medical evaluation and a comprehensive TTE included RV systolic such as tricuspid annular plane systolic excursion (TAPSE), pulmonary artery systolic pressure (PASP) derived from the tricuspid regurgitation (TR), the derived RV-pulmonary circulation (PC) coupling or TAPSE/PASP, pulmonary vascular resistances (PVR) derived from TR/RV outflow tract velocity (RVOT VTI) and diastolic function parameters. The cohort was divided in 4 groups of age: group 1: 300 subjects from 18 to 35 years; group 2: 383 subjects from 36 to 50; group 3: 451 from 50 to 79 years and group 4: 43 subjects > than 80 years of age The oldest subjects were completely independent in daily living activities. The groups were compared by ANOVA and the difference was adjusted by gender, BMI and mean arterial pressure. For each group the difference between genders was tested by T-Test. Multivariate analysis was used to evaluate the relationship between RV function and structure indexes and covariates selected according to pathologic relevance.

Results

There was a progressive increase in blood pressure (BP) according to age. The RV longitudinal diameter, right E/A ratio, right ventricular outflow tract acceleration time and TAPSE/PASP decreased according to age increase (p<0.0001). The right atrial volume indexed by BSA, PASP, PVR increase with age (p<0.0001). Either TAPSE or Sm were unaffected by age. Women had constantly smaller RV longitudinal diameters, right atrium volume index, TAPSE and TAPSE/PASP (p<0.001). In the multiple regression analysis, though the proportion of variance of the dependent variables predicted by the independent ones was very small, age, BSA, gender, E/Em and the longitudinal diameter of the RV were independent predictors of TAPSE/PASP. Heart rate, left ventricular (LV) diastolic function, stroke volume (SV) and TR were independently related to Sm, while age, BSA, LV diastolic function and SV were independently related to TAPSE.

Conclusion

With ageing there is a progressive involvement not only of the LV in terms of adaptation to increase afterload related to arterial stiffness but also of the RV. With age PVR and PASP increase while RV contractility is still unchanged. While the RV adapts very well to volume overload, even the physiologic increase in PASP with age, causes a RV-PC coupling impairment.

Breast Cancer Screening and Care Among Black Sexual Minority Women: A Scoping Review of the Literature from 1990 to 2017

Introduction: Black women are more likely to be diagnosed at later stages of breast cancer compared with White women due to lower frequency of screening and lack of timely follow-up after abnormal screening results. Disparities in breast cancer screening, risk, and mortality are present within both Black women and sexual minority communities; however, there exists limited research concerning breast cancer care among Black sexual minority women. Materials and Methods: This scoping review examines the literature from 1990 to 2017 of the breast cancer care continuum among Black sexual minority women, including behavioral risk factors, screening, treatment, and survivorship. A total of 91 articles were identified through PubMed, PsycINFO, and CINAHL (Cumulative Index to Nursing and Allied Health Literature) databases. Fifteen articles were selected for data extraction, which met the criteria for including Black/African American women, discussing breast cancer care among both racial and sexual minorities, and being a peer-reviewed article. Results: The 15 articles were primarily within urban contexts, and defined sexual minorities as lesbian or bisexual women. Across all the studies, Black sexual minority women were highly under-represented, and key conclusions are not fully applicable to Black sexual minority women. Sexual minority women had a higher prevalence of breast cancer risk factors (i.e., nulliparity, fewer mammograms, higher alcohol intake, and lower oral contraceptive use). Furthermore, some studies noted homophobia from health providers as potential barriers to engagement in care for sexual minority women. Conclusions: The lack of studies concerning Black sexual minority women in breast cancer care indicates the invisibility of a group that experiences multiple marginalized identities. More research is needed to capture the dynamics of the breast cancer care continuum for Black sexual minority women.

Biomechanics of the human intervertebral disc: A review of testing techniques and results

Many experimental testing techniques have been adopted in order to provide an understanding of the biomechanics of the human intervertebral disc (IVD). The aim of this review article is to amalgamate results from these studies to provide readers with an overview of the studies conducted and their contribution to our current understanding of the biomechanics and function of the IVD. The overview is presented in a way that should prove useful to experimentalists and computational modellers. Mechanical properties of whole IVDs can be assessed conveniently by testing 'motion segments' comprising two vertebrae and the intervening IVD and ligaments. Neural arches should be removed if load-sharing between them and the disc is of no interest, and specimens containing more than two vertebrae are required to study 'adjacent level' effects. Mechanisms of injury (including endplate fracture and disc herniation) have been studied by applying complex loading at physiologically-relevant loading rates, whereas mechanical evaluations of surgical prostheses require slower application of standardised loading protocols. Results can be strongly influenced by the testing environment, preconditioning, loading rate, specimen age and degeneration, and spinal level. Component tissues of the disc (anulus fibrosus, nucleus pulposus, and cartilage endplates) have been studied to determine their material properties, but only the anulus has been thoroughly evaluated. Animal discs can be used as a model of human discs where uniform non-degenerate specimens are required, although differences in scale, age, and anatomy can lead to problems in interpretation.

The Effect of Posture on the Strength of the Lumbar Spine

Experiments were performed on cadaveric lumbar intervertebral joints in order to assess the effects of heavy lifting on the lumbar spine. It was found that in the simulated erect lordotic posture, the apophyseal joints can resist a significant proportion of the intervertebral compressive force. Slightly flexed lumbar joints have a compressive strength that comfortably exceeds the forces generated by heavy lifting. Hyperflexion just beyond the normal limit of motion can render lumbar intervertebral discs vulnerable to posterior prolapse when compressed by physiological loads. It is concluded that no injury should be sustained by the osteoligamentous lumbar spine as a result of a single heavy lift provided that the lumbar spine is kept slightly flexed.

Brain Structural and Vascular Anatomy Is Altered in Offspring of Pre-Eclamptic Pregnancies: A Pilot Study

BACKGROUND AND PURPOSE

Pre-eclampsia is a serious clinical gestational disorder occurring in 3%-5% of all human pregnancies and characterized by endothelial dysfunction and vascular complications. Offspring born of pre-eclamptic pregnancies are reported to exhibit deficits in cognitive function, higher incidence of depression, and increased susceptibility to stroke. However, no brain imaging reports exist on these offspring. We aimed to assess brain structural and vascular anatomy in 7- to 10-year-old offspring of pre-eclamptic pregnancies compared with matched controls.

MATERIALS AND METHODS

Offspring of pre-eclamptic pregnancies and matched controls (n = 10 per group) were recruited from an established longitudinal cohort examining the effects of pre-eclampsia. Children underwent MR imaging to identify brain structural and vascular anatomic differences. Maternal plasma samples collected at birth were assayed for angiogenic factors by enzyme-linked immunosorbent assay.

RESULTS

Offspring of pre-eclamptic pregnancies exhibited enlarged brain regional volumes of the cerebellum, temporal lobe, brain stem, and right and left amygdalae. These offspring displayed reduced cerebral vessel radii in the occipital and parietal lobes. Enzyme-linked immunosorbent assay analysis revealed underexpression of the placental growth factor among the maternal plasma samples from women who experienced pre-eclampsia.

CONCLUSIONS

This study is the first to report brain structural and vascular anatomic alterations in the population of offspring of pre-eclamptic pregnancies. Brain structural alterations shared similarities with those seen in autism. Vascular alterations may have preceded these structural alterations. This pilot study requires further validation with a larger population to provide stronger estimates of brain structural and vascular outcomes among the offspring of pre-eclamptic pregnancies.

Impact of placental growth factor deficiency on early mouse implant site angiogenesis

Effects of placental growth factor (PGF), an angiokine product of fetal trophoblasts and maternal decidual cells, on early decidual angiogenesis are undefined. We used whole-mount immunofluorescence analyses to compare uterus and gestation day 4.5-9.5 mouse implantation sites that differed genetically in fetal or maternal PGF deficiency. Implant site number and embryonic development were similar in Pgf(-/-) and Pgf(+/+) females although Pgf(-/-) lymphatic vessels were anomalous. Correct, fine branching angiogenesis of anti-mesometrial vessels required both conceptus and maternal PGF; correct mesometrial branching angiogenesis depended solely upon conceptus PGF. Thus, PGF is non-redundant for optimizing branching angiogenesis in early decidua.

Proton vibrational dynamics in lithium imide investigated through incoherent inelastic and Compton neutron scattering

In the present study we report neutron spectroscopic measurements on polycrystalline lithium imide, namely, incoherent inelastic neutron scattering at 20 K, and neutron Compton scattering from 10 K up to room temperature. From the former technique the H-projected density of phonon states up to 100 meV is derived, while the latter works out the spherically averaged single-particle (i.e., H, Li, and N) momentum distributions and, from this, the mean kinetic energies. Only for H at the lowest investigated temperature, non-gaussian components of its momentum distribution are detected. However, these components do not seem directly connected to the system anharmonicity, being fully compatible with the simple N-H bond anisotropy. Neutron data are also complemented by ab initio lattice dynamics simulations, both harmonic and, at room temperature, carried out in the framework of the so-called "quantum colored noise thermostat" method. The single-particle mean kinetic energies in lithium imide as a function of temperature show a quite peculiar behavior at the moment not reproduced by ab initio lattice dynamics methods, at least as far as H and Li are concerned. As matter of fact, neither their low temperature values nor their temperature trends can be precisely explained in terms of standard phonon calculations.

Attitudes and program preferences of African-American urban young adults about pre-exposure prophylaxis (PrEP)

We elicited attitudes about, and service access preferences for, daily oral antiretroviral pre-exposure prophylaxis (PrEP) from urban, African-American young men and women, ages 18-24 years, at risk for HIV transmission through their sexual and drug-related behaviors participating in eight mixed-gender and two MSM-only focus groups in Atlanta, Georgia. Participants reported substantial interest in PrEP associated with its perceived cost, effectiveness, and ease of accessing services and medication near to their homes or by public transportation. Frequent HIV testing was a perceived benefit. Participants differed about whether risk-reduction behaviors would change, and in which direction; and whether PrEP use would be associated with HIV stigma or would enhance the reputation for PrEP users. This provides the first information about the interests, concerns, and preferences of young adult African Americans that can be used to inform the introduction of PrEP services into HIV prevention efforts for this critical population group.

The role of Plantaris Longus in Achilles tendinopathy: a biomechanical study

BACKGROUND

The Plantaris Longus Tendon (PLT) may be implicated in Achilles (AT) tendinopathy. Different mechanical characteristics may be the cause. This study is designed to measure these.

METHODS

Six PLT and six AT were harvested from frozen cadavers (aged 65-88). Samples were stretched to failure using a Minimat 2000™ (Rheometric Scientific Inc.). Force and elongation were recorded. Calculated tangent stiffness, failure stress and strain were obtained. Averaged mechanical properties were compared using paired, one-tailed t-tests.

RESULTS

Mean stiffness was higher (p<0.001) in the PLT, measuring 5.71 N/mm (4.68-6.64), compared with 1.73 N/mm (1.40-2.22) in AT. Failure stress was also higher (p<0.01) in PLT: 1.42 N/mm(2) (0.86-2.23) AT: 0.20 N/mm(2) (0.16-0.25). Failure strain was less (p<0.05) in PLT: 14.1% (11.5-16.8) than AT: 21.8% (14.9-37.9).

CONCLUSIONS

The PLT is stiffer, stronger than AT, demonstrating potential for relative movement under load. The stiffer PLT could tether AT and initiate an inflammatory response.

Circulatory and renal consequences of pregnancy in diabetic NOD mice

OBJECTIVES

Women with diabetes have elevated gestational risks for severe hemodynamic complications, including preeclampsia in mid- to late pregnancy. This study employed continuous, chronic radiotelemetry to compare the hemodynamic patterns in non-obese diabetic (NOD) mice who were overtly diabetic or normoglycemic throughout gestation. We hypothesized that overtly diabetic, pregnant NOD mice would develop gestational hypertension and provide understanding of mechanisms in progression of this pathology.

STUDY DESIGN

Telemeter-implanted, age-matched NOD females with and without diabetes were assessed for six hemodynamic parameters (mean, systolic, diastolic, pulse pressures, heart rate and activity) prior to mating, over pregnancy and over a 72 h post-partum interval. Urinalysis, serum biochemistry and renal histopathology were also conducted.

RESULTS

Pregnant, normoglycemic NOD mice had a hemodynamic profile similar to other inbred strains, despite insulitis. This pattern was characterized by an interval of pre-implantation stability, post implantation decline in arterial pressure to mid gestation, and then a rebound to pre-pregnancy baseline during later gestation. Overtly diabetic NOD mice had a blood pressure profile that was normal until mid-gestation then become mildly hypotensive (-7 mmHg, P < 0.05), severely bradycardic (-80 bpm, P < 0.01) and showed signs of acute kidney injury. Pups born to diabetic dams were viable but growth restricted, despite their mothers' failing health, which did not rebound post-partum (-10% pre-pregnancy pressure and HR, P < 0.05).

CONCLUSIONS

Pregnancy accelerates circulatory and renal pathologies in overtly diabetic NOD mice and is characterized by depressed arterial pressure from mid-gestation and birth of growth-restricted offspring.

Isotope quantum effects on the water proton mean kinetic energy

A deep inelastic neutron scattering experiment, performed on D(2)O in the stable and metastable liquid phases, provides evidence for isotope quantum effects in the proton or deuteron single particle dynamics along the hydrogen bond. The deuteron mean kinetic energy extracted from the experimental data in the metastable supercooled phase (T = 276.15 K) exceeds the zero point energy and scales as sqrt[2] with that of protons in supercooled light water, at T = 269.15 K. The present data support the suggestion that even small changes in the short range environment of a deuteron or proton have a strong influence on its quantum behavior.

Attack on all fronts: functional relationships between aerial and root parasitic plants and their woody hosts and consequences for ecosystems

This review discusses how understanding of functional relationships between parasitic plants and their woody hosts have benefited from a range of approaches to their study. Gross comparisons of nutrient content between infected and uninfected hosts, or parts of hosts, have been widely used to infer basic differences or similarities between hosts and parasites. Coupling of nutrient information with additional evidence of key processes such as transpiration, respiration and photosynthesis has helped elucidate host-parasite relationships and, in some cases, the anatomical nature of their connection and even the physiology of plants in general. For example, detailed analysis of xylem sap from hosts and parasites has increased our understanding of the spatial and temporal movement of solutes within plants. Tracer experiments using natural abundance or enriched application of stable isotopes ((15)N, (13)C, (18)O) have helped us to understand the extent and form of heterotrophy, including the effect of the parasite on growth and functioning of the host (and its converse) as well as environmental effects on the parasite. Nutritional studies of woody hosts and parasites have provided clues to the distribution of parasitic plants and their roles in ecosystems. This review also provides assessment of several corollaries to the host-parasite association.

Vertebral fractures in the elderly may not always be "osteoporotic"

INTRODUCTION

Vertebral fractures in the elderly are often assumed to be "osteoporotic" and require anti-osteoporosis therapy. However, some of these fractures may represent traumatic injuries to vertebrae that have comparatively normal bone mineral density (BMD). We hypothesize that radiographic appearances can be used to differentiate between "osteoporotic" fractures of vertebrae with low BMD and strength, and "traumatic" fractures of vertebrae with normal BMD and strength.

METHODS

73 cadaveric specimens (each comprising two vertebrae with the intervening intervertebral disc and ligaments) were obtained from donors aged 42 to 91 (mean 74) years. Areal BMD was measured in the lateral projection for each vertebral body, using DXA. Each specimen was secured in metal cups containing dental plaster, and compressed to failure at 3mm/s on a computer-controlled materials testing machine. Mechanical failure was detected by a reduction in the gradient of the load-deformation curve. Compressive deformation for each specimen was limited to 4mm in order to prevent gross destruction of the vertebra. Radiographs, obtained before and after mechanical loading, were assessed by an experienced radiologist (GJ) who was blinded to BMD and mechanical data. The algorithm-based qualitative method (ABQ) was used to assign each specimen to two possible outcomes: no discernible fracture of either vertebra, or fracture. The latter were further classified into specimens with osteoporotic fracture and those with traumatic fracture, by applying additional criteria for differential diagnosis. The relationship of failure load to BMD was tested using correlation. BMD and failure load for the three diagnostic outcomes were compared using one-way analysis of variance (ANOVA).

RESULTS

Failure load was proportional to BMD (R=0.63, p<0.001). "Osteoporotic," "traumatic" and "no discernible" fractures were reported in 16, 26 and 31 specimens respectively. "Traumatic" fracture specimens had higher BMD and failed at higher loads than "osteoporotic" fracture specimens (p<0.05).

CONCLUSIONS

Some vertebral fractures in the elderly may be traumatic rather than osteoporotic in origin. Our radiological criteria help to differentiate between them.

Tensile properties of the annulus fibrosus II. Ultimate tensile strength and fatigue life

Part I of this study showed that collagen fibres do need not need to be continuous to reinforce the annulus fibrosus, and that 15-mm-wide samples of annulus retain about 44% of their in situ stiffness and strength when stretched vertically. Part II investigated the ultimate tensile strength (UTS) and fatigue life of such samples. Vertical slices, 5 mm thick and 30 mm wide, were cut from the anterior and posterior margins of the annulus and adjacent vertebral bodies. Each slice was divided sagittally to obtain a matched pair of specimens. The bony ends of each specimen were secured in a materials testing machine so that the annulus could be stretched vertically, as occurs during bending movements of the spine in life. One of each pair of specimens was stretched to failure to obtain its UTS; the other was cyclically loaded at some fraction of the UTS until failure occurred. Tensile failure started with the hyaline cartilage end-plate being stripped off the underlying bone and ended with the most peripheral annular fibres pulling out of the matrix. The estimated in situ strength in the vertical direction was 3.9 MPa for the anterior annulus and 8.6 MPa for the posterior annulus. Fatigue failure could occur in less than 10000 cycles if the tensile force exceeded 45% of the UTS. The results explain why radial fissures often fail to penetrate the peripheral annulus. When compared with in vivo measurements of spinal loading, they suggest that repetitive forward bending movements could cause fatigue failure of the posterior annulus.

Vertebral fractures usually affect the cranial endplate because it is thinner and supported by less-dense trabecular bone

INTRODUCTION

Cranial endplates of human vertebrae are injured more often than caudal, in both young and elderly spines. We hypothesise that cranial endplates are inherently vulnerable to compressive loading because of structural asymmetries in the vertebrae.

METHODS

Sixty-two "motion segments" (two vertebrae and the intervening disc and ligaments) were obtained post-mortem from thirty-five human spines (17F/18M, age 48-92 yrs, all spinal levels from T8-9 to L4-5). Specimens were compressed to failure while positioned in 2-6 degrees of flexion, and the resulting damage characterised from radiographs and at dissection. 2 mm-thick slices of 94 vertebral bodies (at least one from each motion segment) were cut in the mid-sagittal plane, and in a para-sagittal plane through the pedicles. Microradiographs of the slices were subjected to image analysis to determine the thickness of each endplate at 10 locations. Optical density of the endplates and adjacent trabecular bone was also measured. Measurements obtained in cranial and caudal regions, and in mid-sagittal and pedicle slices, were compared using repeated measures ANOVA with age, level and gender included as between-subject factors. Linear regression was used to determine significant predictors of compressive strength (failure stress).

RESULTS

Fracture affected the cranial endplate in 55/62 specimens. Cranial endplates were thinner than caudal (p=0.003) by 14% and 11% on average, in mid-sagittal and pedicle slices respectively. Caudal but not cranial endplates were thicker at lower spinal levels (p=0.01). Optical density of trabecular bone adjacent to the endplates was 6% lower cranially than caudally (p=0.004), and the average optical density of trabecular bone in mid-sagittal slices was 10% lower in women than in men (p=0.025). Vertebral yield stress (mean 2.22 MPa, SD 0.77 MPa) was best predicted by the density of trabecular bone underlying the cranial endplate of the mid-sagittal slice of the fractured vertebra (r(2)=0.67, p=0.0006).

CONCLUSIONS

When vertebrae are compressed naturally by adjacent intervertebral discs, cranial endplates usually fail before caudal endplates because they are thinner and supported by less dense trabecular bone.

Does initial spacing influence crown and hydraulic architecture of Eucalyptus marginata?

Long-term declines in rainfall in south-western Australia have resulted in increased interest in the hydraulic characteristics of jarrah (Eucalyptus marginata Donn ex Smith) forest established in the region's drinking water catchments on rehabilitated bauxite mining sites. We hypothesized that in jarrah forest established on rehabilitated mine sites: (1) leaf area index (L) is independent of initial tree spacing; and (2) more densely planted trees have less leaf area for the same leaf mass, or the same sapwood area, and have denser sapwood. Initial stand densities ranged from about 600 to 9000 stems ha(-1), and trees were 18 years old at the time of sampling. Leaf area index was unaffected by initial stand density, except in the most sparsely stocked stands where L was 1.2 compared with 2.0-2.5 in stands at other spacings. The ratio of leaf area to sapwood area (A(l):A(s)) was unaffected by tree spacing or tree size and was 0.2 at 1.3 m height and 0.25 at the crown base. There were small increases in sapwood density and decreases in leaf specific area with increased spacing. Tree diameter or basal area was a better predictor of leaf area than sapwood area. At the stand scale, basal area was a good predictor of L (r(2) = 0.98, n = 15) except in the densest stands. We conclude that the hydraulic attributes of this forest type are largely independent of initial tree spacing, thus simplifying parameterization of stand and catchment water balance models.

Can compressive stress be measured experimentally within the annulus fibrosus of degenerated intervertebral discs?

The aims were to assess the ability of a pressure transducer to measure compressive stress within the annulus fibrosus of degenerated intervertebral discs. Measurements could help to explain the mechanisms of disc failure and low back pain.

The methods used were as follows. Thirteen full-depth cores of annulus, 7 mm in diameter, were removed from the middle and outer annuli of two severely degenerated human discs and constrained within a metal cylinder. Then static compressive forces were applied by a planeended metal indenter of diameter 6.8 mm, while a strain-gauged pressure transducer, side mounted in a needle of diameter 0.9 mm and calibrated in saline, was pulled through the issue. The transducer output was converted into stress, and the average measured stress was compared with the nominal applied stress. Measurements were repeated at up to 21 load levels, with the transducer oriented vertically and horizontally.

The results showed that the measured and applied stress were linearly related (average r2=0.98) with a mean gradient (calibration factor) of 0.98 (vertical stress) and 0.92 (horizontal stress). Gradients ranged between 1.28 and 0.73. Damaged transducers grossly under-recorded ‘stress’ even though their output remained proportional to applied load.

It was concluded that pressure transducers can measure compressive stress inside a degenerated human annulus. The tissue is sufficiently deformable to allow efficient coupling of stress between the matrix and transducer membrane. Damage to the transducer can give misleading results.

Soil water nitrate and ammonium dynamics under a sewage effluent irrigated eucalypt plantation

Managed forests and plantations are appropriate ecosystems for land-based treatment of effluent, but concerns remain regarding nutrient contamination of ground- and surface waters. Monthly NO3-N and NH4-N concentrations in soil water, accumulated soil N, and gross ammonification and nitrification rates were measured in the second year of a second rotation of an effluent irrigated Eucalyptus globulus plantation in southern Western Australia to investigate the separate and interactive effects of drip and sprinkler irrigation, effluent and water irrigation, irrigation rate, and harvest residues retention. Nitrate concentrations of soil water were greater under effluent irrigation than water irrigation but remained <15 mg L(-1) when irrigated at the normal rate (1.5-2.0 mm d(-1)), and there was little evidence of downward movement. In contrast, NH4-N concentrations of soil water at 30 and 100 cm were generally greater under effluent irrigation than water irrigation when irrigated at the normal rate because of direct effluent NH4-N input and indirect ammonification of soil organic N. Drip irrigation of effluent approximately doubled peak NO3-N and NH4-N concentrations in soil water. Harvest residue retention reduced concentrations of soil water NO3-N at 30 cm during active sprinkler irrigation, but after 1 yr of irrigation there was no significant difference in the amount of N stored in the soil system, although harvest residue retention did enhance the "nitrate flush" in the following spring. Gross mineralization rates without irrigation increased with harvest residue retention and further increased with water irrigation. Irrigation with effluent further increased gross nitrification to 3.1 mg N kg(-1) d(-1) when harvest residues were retained but had no effect on gross ammonification, which suggested the importance of heterotrophic nitrification. The downward movement of N under effluent irrigation was dominated by NH4-N rather than NO3-N. Improving the capacity of forest soils to store and transform N inputs through organic matter management must consider the dynamic equilibrium between N input, uptake, and immobilization according to soil C status, and the effect changing microbial processes and environmental conditions can have on this equilibrium.

Changes in gas exchange versus leaf solutes as a means to cope with summer drought in Eucalyptus marginata

Two of the ways in which plants cope with water deficits are stomatal closure and "osmotic adjustment". We sought to assess the contributions of these processes to maintenance of leaf hydration in field-grown, 7-year-old Eucalyptus marginata. Plants were exposed to their normal summer drought (controls) or supplied with additional water (irrigated). Irrigation increased photosynthesis by 30% in E. marginata. These increases in photosynthesis were related to an 80% increase in g (s). However, there was no difference in substomatal CO(2) concentrations between treatments, or in chloroplast CO(2) concentrations, as indicated by carbon isotope composition of leaf soluble sugars. This suggests that impaired mesophyll metabolism may partially explain slower rates of photosynthesis in plants exposed to their normal summer drought. There was no difference in concentrations of solutes or osmotic potential between non-irrigated and irrigated individuals, perhaps because relative water content was the same in non-irrigated and irrigated plants due to stomatal sensitivity to water deficits. Irrespective of the absence of osmotic adjustment, analysis of leaf solutes gave a clear indication of the major groups of compounds responsible for maintaining cell osmotic potential. Soluble sugars were three times as abundant as amino acids. Proline, a putatively osmotically active amino acid, contributed less than 1% of total solutes. These patterns of solutes in E. marginata are consistent with a growing body of literature arguing a greater role for carbohydrates and cyclitols and lesser role for amino acids in maintaining osmotic potential. Our data suggest the primary mechanism by which E. marginata coped with drought was partial stomatal closure; however, we cannot discount the possibility of osmotic adjustment under more severe water deficits.

Measurement of the kinetic energy and lattice constant in hcp solid helium at temperatures 0.07-0.4 K

The single atom kinetic energy kappa of high purity solid hcp 4He has been measured by neutron Compton scattering, at temperatures between 0.07 and 0.4 K and a pressure of 40 bar. Within statistical error of approximately 2% no change in kappa was observed. The values of kappa at approximately 0.07 K were the same in a single crystal and a polycrystalline sample and were also unaffected (within statistical error) by the addition of 10 ppm of 3He. The lattice constant was also found to be independent of temperature to within 1 part in 2000. These results suggest that the supersolid transition in 4He has a different microscopic origin to the superfluid transition in the liquid.

A potential role for the endothelin ETA receptor in salt-sensitive hypertension of the proANP gene-disrupted mouse

We have previously shown that the partial disruption of the gene for atrial natriuretic peptide (ANP) results in a salt-sensitive phenotype. The present study examined the possibility that alterations in either the ANP natriuretic pathway or endothelin (ET) system in the kidney of the salt-challenged ANP +/- mouse was responsible for its salt-sensitive phenotype. Plasma ANP levels and renal cGMP activity were increased in response to a salt load in both ANP +/+ and +/- mice. However, the mRNA expression of proANP was found to be increased only in the ANP +/- kidney along with its guanylyl cyclase-linked receptor, NPRA; the upregulation of NPRA mRNA was limited to the renal medulla. This suggests that the renal ANP pathway remains capable of responding to a salt load in the ANP +/- animal, but may be compensating for other dysfunctional pathways. We also report a significant increase in renal ET-1 mRNA and ETA receptor protein expression in medulla and cortex of the salt-treated, ANP +/- mouse, but not its wild-type counterpart. In fact, ETA expression decreased in the renal cortex of the ANP +/+ salt-treated animal. The ETB receptor expression was not affected by diet in either genotype. We hypothesize that the salt-sensitive hypertension in the ANP +/- mouse is exacerbated, and possibly driven by the vasoconstrictive effects resulting from an upregulated ET-1/ETA pathway.

Nitric oxide attenuates resistance to doxorubicin in three-dimensional aggregates of human breast carcinoma cells

Compared with monolayer culture, tumour cells cultured as multicellular aggregates (spheroids) exhibit much higher levels of resistance to chemotherapeutic agents, a phenomenon known as multicellular resistance (MCR). Associated with multicellular aggregates is a heterogeneous microenvironment characterised by gradients in oxygen, pH, and nutrients. We previously showed that nitric oxide (NO) signalling plays an important role in the regulation of chemosensitivity in cancer cells cultured as monolayer, and that hypoxia increases resistance to anti-cancer agents largely through a mechanism involving the inhibition of NO signalling. The goal of the present study was to determine whether NO mimetics chemosensitize breast cancer cells in spheroid cultures. Survival of MDA-MB-231 breast carcinoma cells was determined by clonogenic assay following spheroid culture, doxorubicin exposure, and NO mimetic administration. When spheroids were incubated for 24 h with the NO mimetics diethylenetriamine/nitric oxide adduct (DETA/NO) and glyceryl trinitrate (GTN), cell survival after doxorubicin (200 microM) exposure was decreased by 33% (p<0.006) and by up to 47% (p<0.02), respectively. Nitric oxide-mediated signalling involves the generation of the second messenger cyclic guanosine monophosphate (cGMP). Administration of a non-hydrolysable cGMP analogue, 8-Bromo-cGMP, significantly decreased MCR (p<0.04). The effect of NO mimetic exposure on tumour cell chemosensitivity was not due to increased penetration of doxorubicin into spheroids, nor was it associated with an increase in cell proliferation. These results suggest that NO mimetics attenuate MCR to doxorubicin through a mechanism involving cGMP-dependent signalling. Therefore, NO-mimetics may potentially be used as chemosensitizers in cancer therapy.

One-dimensional and two-dimensional quantum systems on carbon nanotube bundles

We report the first measurement of the structure of 4He atoms adsorbed on bundles of single-walled carbon nanotubes. Neutron diffraction techniques and nanotube samples closed at the end were used. At low coverage, 4He forms a 1D, single line lattice along the grooves between two nanotubes on the surface of the nanotube bundles. As coverage is increased, additional lines of 1D lattices form along the grooves. This is followed by an incommensurate, 2D monolayer covering the whole nanotube bundle surface. The lattice constants of these 1D and 2D systems are largely independent of filling once a single 1D line is formed. No occupation of the interstitial channels between nanotubes is observed in the present sample.

Common therapeutic strategies in the management of sexual dysfunction and cardiovascular disease

Sexual dysfunction is a frequent complication of treated and untreated cardiovascular disease. In fact, approximately 30% of hypertensives have been found to suffer from erectile dysfunction (ED) resulting from arterial dysfunction. Recent evidence has suggested that ED may be an early indicator of subclinical cardiovascular disease. In women, the evidence is similar, but more limited, showing that in hypertensive patients there is an increased prevalence of sexual dysfunction involving decreased vaginal lubrication, decreased orgasm, and increased pain. Clouding the issue, however, is that some antihypertensive agents may induce sexual dysfunction in hypertensives with normal sexual function. In contrast to the chronic treatments used in hypertension, therapies for ED involve acute treatments (none currently approved for women) targeting vasodilation of penile arteries, resulting in erection. Common to the treatment of hypertension and ED is that the current therapies were not designed to target underlying disorders of local, neural, vascular, or endocrine origin. In fact, while blood pressure is lowered, and erectile responses are improved with the respective therapies, the causal abnormalities may progress thereby limiting the long-term effectiveness of the medication. Some antihypertensive agents have been shown to have additional effects beyond blood pressure reduction and their impact on sexual function is a key focus of this review. This review examines the current and future strategies for treatments of male and female sexual dysfunction and the potential for therapeutic modalities that go beyond the recovery of the responses by targeting the fundamental mechanisms common to both sexual dysfunction and cardiovascular disease.

Inhomogeneous level splitting in Pr 2-x BixRu2O7

We report that Bi doping drives Pr 2-x BixRu2O7 from an antiferromagnetic insulator (x = 0) to a metallic paramagnet (x approximately 1) with a broad low T maximum in C/T. Neutron scattering reveals local low energy spin excitations (variant Planck's omega approximately 1 meV) with a spectrum that is unaffected by heating to k(B)T >> variant Planck's omega. We show that a continuous distribution of splittings of the non-Kramers Pr3+ ground-state doublet such as might result from various types of lattice strain can account for all the data.

Neural arch load-bearing in old and degenerated spines

We validate a technique for measuring neural arch load-bearing in cadaveric spines, and use it to test the hypothesis that such load-bearing rises to high levels in old and degenerated spines. Fifty-nine cadaveric lumbar motion segments, aged 19-92 yr, were subjected to compressive creep loading to reduce intervertebral disc water content and height to in vivo levels. The distribution of compressive "stress" within the disc was then measured by pulling a miniature pressure transducer, side-mounted in a 1.3mm-diameter needle, along its mid-sagittal diameter. During these measurements, the motion segment was subjected to a compressive load of 2 kN, and positioned in 2 degrees of extension to simulate erect standing. Measurements of compressive "stress" were integrated over disc area, and this force subtracted from the applied 2 kN to give the force resisted by the neural arch. An empirical calibration factor was applied to normalise results from each disc to values obtained under conditions when all of the compressive force could be assumed to pass through the disc. Disc degeneration was graded macroscopically on a scale of 1-4. Validation tests showed that calculated values of disc loading were proportional to actual applied load (r(2)>0.96) and predicted it with errors of 2-8%. Neural arch load-bearing in non-degenerated specimens was generally less than 20%, but averaged 49% for specimens aged over 70 yr. Multiple regression showed that neural arch load bearing (%)=14.4 x disc degeneration score+0.46 x age-35. These results indicate a substantial shift in vertebral load-bearing with increasing age and degeneration.

Update on central function relevant to sex: remodeling the basis of drug treatments for sex and the brain

Sexual function draws on a complex network of peripheral and central neural pathways. The standard focus on erectile difficulties and peripheral therapies has been highly successful clinically but there are many unresolved issues in men and newly discussed issues in women that will likely benefit from improved understanding of the central nervous system and sexual function. The spectrum of future therapies, based on evolving central neurophysiological understanding, will include the management of problems related to orgasm, ejaculation, desire, motivation, anxiety, and pleasure. This new range of therapies will employ old and new neurochemicals and pathways singly or in combination. The capability of hormones to modulate many of the sexual pathways will also contribute to the rise of multiagent therapy. The expanded understanding, in combination with enhanced imaging technologies, will renew the role of diagnosis and cause-specific treatment.

A framework for the present and future development of experimental models of female sexual dysfunction

Female sexual dysfunction (FSD) is currently categorized according to disorders of (i). desire, (ii). arousal, (iii). orgasm and (iv). sexual pain. The advancement of research defining the physiological, pathophysiological and psychological mechanisms of these disorders, and to develop treatments for FSD, has been hampered by the paucity of experimental paradigms and animal models. It may be that animal models of FSD are best suited to address arousal disorders that include persistent or routine inability to attain or maintain genital lubrication or engorgement. Although still limited in scope, experimental models of FSD have involved a range of in vitro to in vivo methodologies. Specifically, the in vitro and in situ models include vaginal or clitoral smooth muscle preparations, histological evaluation and vaginal blood flow assessments. Previously, in vivo studies of sexual responses focussed on behavioral paradigms involving lordotic posturing and receptivity, as well as indices of motivation using a dual chamber pacing method. Recently, a new model of female sexual arousal was developed using pharmacological CNS stimulation; responses that were found to be sensitive to cardiovascular status, aging and hormonal conditions. It is important that a wide variety of animal models continue to be developed to reflect the multifactorial basis of the condition.

Evidence for centrally initiated genital vasocongestive engorgement in the female rat: findings from a new model of female sexual arousal response

PURPOSE

In spite of rapidly growing interest, few research tools have been developed to study female sexual dysfunction. Using the D(1)/D(2) agonist, apomorphine (APO), our objective was to develop a new model of the sexual arousal response in female rats based on one previously established for the male condition.

METHODS

APO (80 micro g/kg, s.c.) was given during proestrus (P), estrus (E), metestrus (M), early diestrus (DI) and late diestrus (DII), and in ovariectomized (OVX) female Wistar rats. APO-induced behavioral and genital responses were characterized (30 min) using video monitoring.

RESULTS

APO-induced reproducible, periodic morphological changes in the external genitalia. The onset, timing and duration of these female APO responses were consistent with genital vasocongestive arousal (GVA) responses in males (ie erections). APO-induced GVAs occurred throughout the estrous cycle, peaking in E (1.4+/-1.21 overall; 0.9+/-0.64 in DII; 1.8+/-1.66 in E) and were markedly diminished by ovariectomy (OVX, 0.4+/-0.51).

CONCLUSION

APO induced a reproducible sexual arousal response in female rats involving obvious genital vasocongestive engorgement. Further, the findings demonstrate that the APO-induced genital arousal responses are hormonally regulated.