The acid-base transport proteins NHE1 and NBCn1 regulate cell cycle progression in human breast cancer cells

Precise acid-base homeostasis is essential for maintaining normal cell proliferation and growth. Conversely, dysregulated acid-base homeostasis, with increased acid extrusion and marked extracellular acidification, is an enabling feature of solid tumors, yet the mechanisms through which intra- and extracellular pH (pH_i, pH_e) impact proliferation and growth are incompletely understood. The aim of this study was to determine the impact of pH, and specifically of the Na⁺/H⁺ exchanger NHE1 and Na⁺, HCO₃^- transporter NBCn1, on cell cycle progression and its regulators in human breast cancer cells. Reduction of pH_e to 6.5, a common condition in tumors, significantly delayed cell cycle progression in MCF-7 human breast cancer cells. The NHE1 protein level peaked in S phase and that of NBCn1 in G2/M. Steady state pH_i changed through the cell cycle, from 7.1 in early S phase to 6.8 in G2, recovering again in M phase. This pattern, as well as net acid extrusion capacity, was dependent on NHE1 and NBCn1. Accordingly, knockdown of either NHE1 or NBCn1 reduced proliferation, prolonged cell cycle progression in a manner involving S phase prolongation and delayed G2/M transition, and altered the expression pattern and phosphorylation of cell cycle regulatory proteins. Our work demonstrates, for the first time, that both NHE1 and NBCn1 regulate cell cycle progression in breast cancer cells, and we propose that this involves cell cycle phase-specific pH_i regulation by the two transporters.

Improved maternal and child health care access in a rural community

Few studies have measured the extent to which expansion of health services for pregnant women and children in poor rural communities improves access to care and health status. This paper describes an underserved rural community in which health care initiatives increased access to comprehensive care. Over a three-year period, use of preventive services increased, whereas emergency room visits and hospitalizations at the community hospital decreased. Low birthweight, risk of congenital syphilis and childhood tuberculosis, and child mortality all decreased. Provision of comprehensive services was met with increased use of preventive health care and improved health outcomes in this rural community.

Direct contracting: the future of managed care

Direct contracting is an agreement whereby healthcare providers directly contract with employers or health plan purchasing cooperatives to provide healthcare services to their employees or enrollees. While this type of arrangement requires a high degree of integration and cooperation between the delivery and financing of care, the flexibility it offers makes it a necessity in the new world of integrated healthcare financing and delivery systems. This article demonstrates the importance of strong vertical and horizontal links with both other providers and various components of the financing system. It also shows how those organizations with the capacity to finance and assume risk for employers will be most successful and play a major role in the healthcare system of the future.

Visual hallucinations: meaning and management

Visual hallucinations of low vision patients may serve as indicators of trauma, illness and psychological disturbance or concerns. Routine inquiry about them is suggested and two case illustrations of this procedure are presented. Primary consideration is management of patient anxiety and fear, as well as indications for referral to allied professions. The incidence of hallucinations is very likely under-reported, though detailed exploration of the parameters of hallucinations in the visually impaired population can enhance existing knowledge and often alleviate fears of mental illness.