Hemodynamic responses to heat stress in the resting and exercising human leg: insight into the effect of temperature on skeletal muscle blood flow

This study was funded by the Gatorade Sports Science Institute. This article is available from the specified link - Copyright @ 2011 American Physiological SocietyHeat stress increases limb blood flow and cardiac output ((Q) over dot) in humans, presumably in sole response to an augmented thermoregulatory demand of the skin circulation. Here we tested the hypothesis that local hyperthermia also increases skeletal muscle blood flow at rest and during exercise. Hemodynamics, blood and tissue oxygenation, and muscle, skin, and core temperatures were measured at rest and during exercise in 11 males across four conditions of progressive whole body heat stress and at rest during isolated leg heat stress. During whole body heat stress, leg blood flow (LBF), (Q) over dot, and leg (LVC) and systemic vascular conductance increased gradually with elevations in muscle temperature both at rest and during exercise (r(2) = 0.86-0.99; P < 0.05). Enhanced LBF and LVC were accompanied by reductions in leg arteriovenous oxygen (a-vO(2)) difference and increases in deep femoral venous O-2 content and quadriceps tissue oxygenation, reflecting elevations in muscle and skin perfusion. The increase in LVC occurred despite an augmented plasma norepinephrine (P < 0.05) and was associated with elevations in muscle temperature (r(2) = 0.85; P = 0.001) and arterial plasma ATP (r(2) = 0.87; P < 0.001). Isolated leg heat stress accounted for one-half of the increase in LBF with severe whole body heat stress. Our findings suggest that local hyperthermia also induces vasodilatation of the skeletal muscle microvasculature, thereby contributing to heat stress and exercise hyperemia. The increased limb muscle vasodilatation in these conditions of elevated muscle sympathetic vasoconstrictor activity is closely related to the rise in arterial plasma ATP and local tissue temperature.This article has been made available through the Brunel Open Access Publishing Fun

Cervical dysplasia and cancer and the use of hormonal contraceptives in Jamaican women

<p>Abstract</p> <p>Background</p> <p>This study was conducted to determine whether use of hormonal contraceptives is associated with cervical dysplasia and cancer in a population where there is widespread use of hormonal contraception and the rates of cervical cancer remain high at 27.5/100,000.</p> <p>Methods</p> <p>A case-control study was conducted among women visiting the colposcopy and gynaelogical clinics at a tertiary referral hospital. Two hundred and thirty six cases CIN I (72), II (59), III (54), cancer (51) and 102 controls, consented and were interviewed on use of contraceptives using a structured questionnaire. Logistic regression was used to determine odds ratios (ORs) and 95% confidence intervals (CIs) associated with use of hormonal contraception in cases and controls and in low and high risk cases. Recruitment was carried out from 2001–2002.</p> <p>Results</p> <p>Contraceptives used were: oral contraceptives – 35%, injections (depot medroxy progesterone acetate (Depo-provera) – 10%, Intrauterine devices – 2%, combinations of these and tubal ligation – 30%. 23% reported use of 'other' methods, barrier contraceptives or no form of contraception. Barrier contraceptive use was not significantly different between cases and controls. Current and/or past exposure to hormonal contraceptives (HC) by use of the pill or injection, alone or in combination with other methods was significantly higher in the cases. In multivariate analysis with age and number of sexual partners as co-variates, use of hormonal contraception was associated both with disease, [OR, 1.92 (CI 1.11, 3.34; p = 0.02] and severity of the disease [OR, 2.22 (CI 1.05, 4.66) p = 0.036]. When parity and alcohol consumption were added to the model, hormonal contraception was no longer significant. The significant association with high risk disease was retained when the model was controlled for age and number of sexual partners. Depo-provera use (with age and number of sexual partners as covariates) was also associated with disease [OR, 2.43 (CI 1.39, 4.57), p = 0.006] and severity of disease [OR 2.51 (1.11, 5.64) p = 0.027]. With parity and alcohol added to this model, depo-provera use retained significance. Exposure to HC > 4 years conferred more risk for disease and severity of disease.</p> <p>Conclusion</p> <p>Hormonal contraception did confer some risk of dysplasia and women using HC should therefore be encouraged to do regular Pap smear screening.</p

Strengthening the community health program in Liberia: Lessons learned from a health system approach to inform program design and better prepare for future shocks

Background: Arising from the Ebola virus disease (EVD) outbreak, the 2015- 2021 Investment Plan aimed to improve the health status of the Liberian population through building a resilient health system that contributes to achieving equitable health outcomes. Recognizing the significance of community participation in overcoming the EVD outbreak, strengthening community systems emerged as one of the most important strategies for bridging the gap in accessing primary health care (PHC) services. This study reviewed the community health policy development process in order to draw lessons from the health system strengthening efforts in Liberia post-EVD crisis. Methods: A government-led health system analysis approach was applied to assess, review and revise the community health program in Liberia. The mixed method approach combines the use of an adapted tool to assess bottlenecks and solutions during workshops, a qualitative survey (key informant interviews and focus group discussions) to assess perceptions of challenges and perspectives from different stakeholders, and an inter-agency framework – a benchmarks matrix – to jointly review program implementation gaps using the evidence compiled, and identify priorities to scale up of the community program. Results: Stakeholders identified key health system challenges and proposed policy and programmatic shifts to institutionalize a standardized community health program with fit for purpose and incentivized community health assistants to provide PHC services to the targeted populations. The community health program in Liberia is currently at the phase of implementation and requires strengthened leadership, local capacities, and resources for sustainability. Lessons learned from this review included the importance of: establishing a coordination mechanism and leveraging partnership support; using a systems approach to better inform policy shifts; strengthening community engagement; and conducting evidence-based planning to inform policy-makers. Conclusions: This article contributes toward the existing body of knowledge about policy development processes and reforms on community health in Liberia, and most likely other African settings with weak health systems. Community-based systems will play an even bigger role as we move toward building resilience for future shocks and strengthening PHC, which will require that communities be viewed as actors in the health system rather than just clients of health services.</p