Translating political commitments into actions to enhance Universal Health Coverage in the Eastern Mediterranean Region

Background

Many countries in the Eastern Mediterranean Region (EMR) have developed packages of services for achieving Universal Health Coverage (UHC), however, policymakers, especially in resource-constrained countries, still face challenges in delivering equitable, efficient and sustainable health services.

Aims

To provide guidance for EMR countries and develop packages of services for UHC.

Methods

We used information gathered from narrative reviews, national experiences and expert consultations to develop step-by-step guidance for the development of national packages of services for the achievement of UHC by countries in the EMR.

Results

The processes used to develop packages of services varied between EMR countries and these processes may not have involved all relevant stakeholders. We highlight in this paper the iterative processes, including several phases and steps, to be used by EMR countries for developing packages of services for UHC. These processes also make provision for continuous monitoring and revision to make necessary improvements as morbidity patterns evolve.

Conclusion

Developing a package of services for the achievement of UHC is a significant milestone for EMR countries and it is central to shaping the healthcare system for effective delivery of services.

Framing health taxes: learning from low- and middle-income countries

Health taxes are effective policy instruments to save lives, raise government revenues and improve equity. Health taxes, however, directly conflict with commercial actors' interests. Both pro-tax health advocates and anti-tax industry representatives seek to frame health tax policy. Yet, little is known about which frames resonate in which settings and how framing can most effectively advance or limit policies. To fill this gap, we conducted qualitative research in 2022, including focus group discussions, in-depth interviews, document reviews and media analysis on the political economy of health taxes across eight low-income and middle-income countries. Studies captured multiple actors constructing context-specific frames, often tied to broader economic, health and administrative considerations. Findings suggest that no single frame dominates; in fact, a plurality of different frames exist and shape discourse and policymaking. There was no clear trade-off between health and economic framing of health tax policy proposals, nor a straightforward way to handle concerns around earmarking. Understanding how to best position health taxes can empower health policymakers with more persuasive framings for health taxes and can support them to develop broader coalitions to advance health taxes. These insights can improve efforts to advance health taxes by better appreciating political economy factors and constraining corporate power, ultimately leading to improved population-level health.

Conflicting interests, institutional fragmentation and opportunity structures: an analysis of political institutions and the health taxes regime in Pakistan

Pakistan is the world's fifth most populous country, with large segments of its population at risk from non-communicable diseases caused by consumption of harmful products, including tobacco and sugar-sweetened beverages. Even though evidence exists that increased taxes on harmful products leads to consumption reductions as well as increased revenues, Pakistan's health taxes remain low. We seek to understand the reasons for the deficient health tax regime. Much of the existing literature emphasises industry tactics, resources and motivations. We take a different approach and instead focus on political institutions in Pakistan which could help explain deficiencies in the health taxes regime. We employed a mixed method design. We conducted: (1) a detailed analysis of media content, (2) semistructured interviews with key stakeholders (and attended relevant meetings) and (3) an analysis of primary and secondary literature, including legal and policy documents. We identify two key aspects of Pakistan's political institutions which may help explain deficiencies in health taxes. First, we identified structural issues in the design and functioning of key institutions responsible for health taxes, including with respect to federalism, intraelite conflict, interagency coordination and intra-agency fragmentation. Second, we found evidence of an entrenchment of industry interests within governmental institutions, which are characterised by weak frameworks for regulating conflicts of interest. We conclude that gaps and conflict within political institutions, owing to weak design, instability and fragmentation, create political opportunity for industry actors to influence the system to advance their interests. The findings of this research indicate towards needed interventions.

Proposal of International Council for Harmonization (ICH) Guideline for the Approval of Biosimilars

OBJECTIVES

Since the initial release of biosimilars 18 years ago, regulations for their licensing have changed considerably; however, there is no global consensus on these regulations. Establishing harmonized regulatory guidelines for the approval of biosimilars with support from the ICH, an independent, non-profit association under Swiss law, will significantly enhance the affordability of biological drugs.

METHODS

Regulatory guidelines from the Food and Drug Administration (FDA), European Medicines Agency (EMA), Medicines and Healthcare products Regulatory Agency (MHRA), and World Health Organization (WHO) were analyzed for historical changes and elements critical to the safety and efficacy of biosimilars.

RESULTS

Analysis of all EMA and FDA filings show that none of the animal testing and clinical efficacy testing failed because animals do not have the required receptors to initiate pharmacologic responses, and efficacy studies cannot be statistically powered to conclude any results. New analytical technologies will enable good biosimilarity determination, avoiding both tests.

CONCLUSION

Scientifically based ICH guidelines that remove redundant studies will reduce development costs, improve safety, and allow global drug distribution based on single compliance. These guidelines are particularly necessary for emerging countries lacking the expertise and resources to evaluate biosimilar filings.

Self-reported alcohol consumption in doctors

BACKGROUND

The UK government has prioritized reducing the harmful effects of excessive alcohol consumption on mental and physical well-being.

AIMS

To assess self-reported alcohol consumption amongst doctors at an acute London Trust.

METHODS

An opportunistic, anonymous, survey was conducted by Postgraduate Education Fellows over 2 weeks in December 2018. This included all grades of doctors from Foundation Year One to Consultant. The survey consisted of nine questions, modified from the alcohol use disorders identification test (AUDIT) and CAGE questionnaire.

RESULTS

Of 446 doctors within our institution, 109 completed the survey (24%). Fourteen per cent of those surveyed abstained from alcohol, 21% drank monthly or less, 31% drank between two to four times per month, 25% drank two to three times per week and 9% drank greater than four times per week. In the preceding 2 years, 9% reported being unable to do what was expected of them on at least one occasion due to alcohol. Five per cent were concerned about alcohol affecting their performance. Two per cent were annoyed by criticism of their drinking, 9% felt guilty about drinking and 4% needed an eye-opener. Eighteen per cent wanted to reduce their alcohol consumption; however, 43% of the 109 doctors surveyed were uncertain where to seek help.

CONCLUSIONS

Twenty per cent of surveyed doctors reported consuming potentially hazardous levels of alcohol and 18% of respondents wanted to cut down. Forty-three per cent were unaware of sources of support. Our findings suggest a role for collaboration between Occupational Health departments and Postgraduate Education teams to support doctors misusing alcohol.

Access to insulin: applying the concept of security of supply to medicines

Security of supply of medicines is fundamental to ensure health for all. Furthermore, improving access to medicines is included in sustainable development goal 3. However, the concept of security of supply has mostly been applied to food, water and energy. Diversity of supply, vulnerability to disruption, expenditure, infrastructure, stability of exporting countries, ownership of production, price stability, access and equity, affordability, intellectual property, safety and reliability of supply, and countries' capacity to adapt to market changes are all elements of security of supply. Based on these elements, we assessed security of supply for insulin, since access to insulin is a global problem. We found that three multinational companies, in Denmark, France and Germany, control 99% of the value of the global insulin market. Prices and affordability of insulin and access to it vary considerably between countries. Some countries are vulnerable to insulin shortage because they import insulin from only one source. Many countries spend large amounts of money on insulin and costs are increasing. Some countries lack an adequate infrastructure for procurement, supply chain management and distribution of insulin. Applying the security of supply concept to insulin showed that diversification of suppliers needs to be fostered. Global health actors should adopt a security of supply approach to identify medicines that are susceptible to supply issues and address this concern by strategic promotion of local production, strengthening regulatory harmonization, and adding local products to the World Health Organization's programme on prequalification of medicines.

Absolute quantification (ml blood/sec ∗ mm2 tissue) of normal vs. diabetic foot skin microvascular blood perfusion: Feasibility of FM-PPG measurements under clinical conditions

Fluorescence-mediated photoplethysmography (FM-PPG) is the first routine clinical methodology by which to quantifiably measure tissue blood perfusion in absolute terms (mL blood/sec ∗ mm² tissue). The FM-PPG methodology has been described in detail previously in this journal (MVR 114, 2017, 92-100), along with initial proof-of-concept measurements of blood perfusion in both ocular and forearm skin tissues. The motivation for the current study was to investigate whether FM-PPG can be used readily and routinely under realistic clinical conditions. The vehicle for doing this was to measure medial foot capillary blood flow, i.e., tissue perfusion, in 7 normal subjects, mean = 6.76 ± 2.29 E-005 mL/(sec ∙ mm²), and lesion-free areas of 8 type-2 diabetic patients with skin ulceration, mean = 4.67 + 3.15 E-005 mL/(sec ∙ mm²). Thus, perfusion in the diabetics was found to be moderately lower than that in the normal control subjects. Earlier skin perfusion measurements in medial forearms of 4 normal subjects, mean = 2.64 + 0.22 E-005 mL/(sec ∙ mm²), were lower than both the normal and diabetic foot perfusion measurements. Variability in the heartbeat-to-heartbeat blood perfusion pulses in the skin capillaries, defined as the ratio of the standard deviation among beat-to-beat pulses divided by the mean perfusion of those pulses, was determined for each subject. Average variability in foot skin was 21% in the diabetic population, versus 16% for normal subjects; and it was 18% in forearm skin. We conclude that absolute quantitative FM-PPG measurement of skin blood perfusion at the level of nutritive capillaries is feasible routinely under clinical conditions, allowing for quantitative measurement of skin tissue blood perfusion in absolute terms.

[Point mutations in the DNA binding domain of p53 contribute to glioma progression and poor prognosis]

TP53 mutations play a significant role in glioma tumorigenesis. When located in in the DNA binding domain, these mutations can perturb p53 protein conformation and its function, often culminating in altered downstream signaling. Here we describe prevalent pattern of TP53 point mutations in a cohort of 40 glioma patients and show their relevance to gliomagenesis. Point mutations in exon 5-9 of TP53 gene were detected by DNA sequencing. Possible influence of identified mutations at the function of p53 was studied computationally and correlated with the survival. Point mutations in TP53 were detected in 10 glioma samples (25%), out of which 70% were from high grade glioma. A total of 19 TP53 point mutations were identified, out of which 42% were found to be in the DNA binding region of p53. Computational analysis predicted 87.5% of these mutations to be "probably damaging". In three patients with tumors possessing point mutations R273H, R248Q, Y163H and R175H and poor survival times, structural analysis revealed the nature of these mutations to be disruptive and associated with high risk for cancer progression. In high grade glioma, recurrent TP53 point mutations may be the key to tumor progression, thus, emphasizing their significance in gliomagenesis.

Sustainable Development Agenda 2030 thrives on health (Editorial)

Never before has the flight of human imagination made calls for universal development that are so loud and audacious. The all-encompassing Sustainable Development Agenda 2030 (SD Agenda 2030) has evolved over 67 years since the adoption of the Universal Declaration of Human Rights by the United Nations in 1948. Although based on the same principle of universality, the scope of the Agenda is much broader. It is a melting-pot of human rights, environmental movements and the fight against poverty; hence, it is a plan of action for people, the planet and prosperity. Moreover, it also seeks peace as a necessary condition for development.

Prices and availability of locally produced and imported medicines in Ethiopia and Tanzania

Background

To assess the effect of policies supporting local medicine production to improve access to medicines.

Methods

We adapted the WHO/HAI instruments measuring medicines availability and prices to differentiate local from imported products, then pilot tested in Ethiopia and Tanzania. In each outlet, prices were recorded for all products in stock for medicines on a country-specific list. Government procurement prices were also collected. Prices were compared to an international reference and expressed as median price ratios (MPR).

Results

The Ethiopian government paid more for local products (median MPR = 1.20) than for imports (median MPR = 0.84). Eight of nine medicines procured as both local and imported products were cheaper when imported. Availability was better for local products compared to imports, in the public (48% vs. 19%, respectively) and private (54% vs. 35%, respectively) sectors. Patient prices were lower for imports in the public sector (median MPR = 1.18[imported] vs. 1.44[local]) and higher in the private sector (median MPR = 5.42[imported] vs. 1.85[local]). In the public sector, patients paid 17% and 53% more than the government procurement price for local and imported products, respectively.

The Tanzanian government paid less for local products (median MPR = 0.69) than imports (median MPR = 1.34). In the public sector, availability of local and imported products was 21% and 32% respectively, with patients paying slightly more for local products (median MPR = 1.35[imported] vs. 1.44[local]). In the private sector, local products were less available (21%) than imports (70%) but prices were similar (median MPR = 2.29[imported] vs. 2.27[local]). In the public sector, patients paid 135% and 65% more than the government procurement price for local and imported products, respectively.

Conclusions

Our results show how local production can affect availability and prices, and how it can be influenced by preferential purchasing and mark-ups in the public sector. Governments need to evaluate the impact of local production policies, and adjust policies to protect patients from paying more for local products.

Management of suspected scaphoid fractures in accident and emergency departments--time for new guidelines

INTRODUCTION

The objectives of this work were to assess the clinical knowledge of clinicians in the accident and emergency (A&E) departments in England & Wales and evaluate the current trend for the acute management of radiologically normal, but clinically suspected, fractures of the scaphoid.

SUBJECTS AND METHODS

We conducted a telephone survey on 146 A&E senior house officers (SHOs) in 50 different hospitals. This survey assessed the clinicians' experience, their clinical and radiological diagnostic methods, and their initial treatment of suspected scaphoid fractures.

RESULTS

The majority (55.8%) of SHOs performed only one clinical test to diagnose suspected scaphoid fractures. Overall, 41% were unable to cite the number of the radiographic views taken and only 10% of departments have direct access to further radiological investigation. There is wide variation in the early treatment of this injury, with the scaphoid cast used most commonly (46%). The majority of SHOs (89%) were unable to describe the features of immobilisation. The mean follow-up period was 10 days, and 53% of cases were followed-up by the senior staff in A&E. Of SHOs, 54% were not aware of any local guidelines for the management of suspected scaphoid fractures in their departments, and 92% were not aware of the existence of the 1992 British Association for Accident and Emergency Medicine (BAEM) guidelines.

CONCLUSIONS

The clinical knowledge and the management of suspected scaphoid fractures in A&E are unsatisfactory. We, therefore, suggest that the dissemination of up-to-date guidelines could help to educate clinicians to provide better care to the patients.

Process, rationale, and interventions of Pakistan's National Action Plan on Chronic Diseases

Most developing countries do not comprehensively address chronic diseases as part of their health agendas because of lack of resources, limited capacity within the health system, and the threat that the institution of national-level programs will weaken local health systems and compete with other health issues. An integrated partnership-based approach, however, could obviate some of these obstacles. In Pakistan, a tripartite public-private partnership was developed among the Ministry of Health, the nongovernmental organization (NGO) Heartfile, and World Health Organization. This was the first time an NGO participated in a national health program; NGOs typically assume a contractual role. The partnership developed a national integrated plan for health promotion and the prevention and control of noncommunicable diseases (NCDs), which as of January 2006 is in the first stage of implementation. This plan, called the National Action Plan on NCD Prevention, Control, and Health Promotion (NAP-NCD), was released on May 12, 2004, and attempts to obviate the challenges associated with addressing chronic diseases in countries with limited resources. By developing an integrated approach to chronic diseases at several levels, capitalizing on the strengths of partnerships, building on existing efforts, and focusing primary health care on chronic disease prevention, the NAP-NCD aims to mitigate the effects of national-level programs on local resources. The impact of the NAP-NCD on population outcomes can only be assessed over time. However, this article details the plan's process, its perceived merits, and its limitations in addition to discussing challenges with its implementation, highlighting the value of such partnerships in facilitating the missions and mandates of participating agencies, and suggesting options for generalizability.

Butane encephalopathy

Volatile solvent abuse (VSA) is defined at the "intentional inhalation of a volatile substance for the purpose of achieving a euphoric state". The lifetime prevalence of VSA in the UK remains steady at around 15%, the fourth highest rate in Europe, and VSA is the most common form of drug abuse in the 11-15 year age group in England and Wales. A 13 year old girl presented to the accident and emergency unit following inhalation of butane based deodorant, which resulted in a prolonged semiconscious state with encephalopathic symptoms.

Adherence of private practitioners with the National Tuberculosis Treatment Guidelines in Pakistan: a survey report

OBJECTIVE

In Pakistan, over 80% of the patients suffering from TB consult a private practitioner for the initial evaluation. A cross-sectional survey was conducted in seven thickly populated urban communities of Rawalpindi district to evaluate the adherence of private practitioners with TB treatment guidelines as laid down by National Tuberculosis Control Programme (NTP) in Pakistan. The data was collected over 30 days.

METHODS

A young lean man was simulated to act as a TB patient and was provided with a chest X-ray suggestive of TB and two Acid-Fast Bacilli (AFB) positive sputum reports. Only those prescriptions were included for analysis which either had recognized the patient having TB or had any TB drug written in the prescription.

RESULTS

A total of 77 practitioners were visited. Prescriptions of 53 general practitioners fulfilled the inclusion criteria and were analyzed. Only 2 (3.7%) prescriptions out of 53 met the required standard for TB patients as laid down by NTP. Eighty three percent (n = 44) favored a combination drug for the treatment while the rest preferred individual preparations.

CONCLUSIONS

The study reflects the lack of knowledge about standardized TB treatment protocols amongst the private practitioners in Pakistan. Public Private Partnerships between government public health departments and non-governmental organizations working in public health can be a valuable tool in generating mass awareness campaigns.

Tobacco control: National Action Plan for NCD Prevention, Control and Health Promotion in Pakistan

Reliance on revenue generated from tobacco is one of the fundamental barriers to effective tobacco control in Pakistan. The tobacco control component of the National Action Plan for Non-Communicable Diseases Prevention, Control and Health Promotion in Pakistan (NAP-NCD) deems it critical to address this issue. A range of policy and environmental strategies are part of this comprehensive effort; these involve regulating access and limiting demand through restrictions on advertising, marketing, promotion and through price and taxation. The NAP-NCD also encompasses community and school interventions, enforcement of tobacco control policies, cessation programmes, mass media counter-marketing campaigns for both prevention and cessation, and surveillance and evaluation of efforts. As part of NAP-NCD, surveillance of tobacco use has been integrated with a population-based NCD surveillance system. Featuring tobacco prominently as part of an NCD behavioural change strategy and providing wide-ranging information relevant to all aspects of tobacco prevention and control and smoking cessation have been identified as priority area in NAP-NCD. Other priority areas include the gradual phasing out of all types of advertising and eventually a complete ban on advertising; allocation of resources for policy and operational research around tobacco and building capacity in the health system in support of tobacco control. NAP-NCD also stresses on the need to develop and enforce legislation on smuggling contrabands and counterfeiting and legislation to subject tobacco to stringent regulations governing pharmaceutical products. The adoption of measures to discourage tobacco cultivation and assist with crop diversification; integration of guidance on tobacco use cessation into health services and insuring the availability and access to nicotine replacement therapy are also part of NAP-NCD.

Prescription and dispensing practices in public sector health facilities in Pakistan: survey report

OBJECTIVES

To gather information on existing prescription practices, dispensing practices and patient satisfaction in government health services of the NWFP, Baluchistan and Punjab province.

METHODS

A cross sectional study design was used for this purpose. Ten health care facilities were selected from each province keeping appropriate representation from first level health facilities, district health facilities and tertiary care hospital. Analysis of selected indicators was carried out on the basis of provinces, health facilities, gender and different age groups.

RESULTS

Documentation of 914 responses was completed from three provinces. Almost equal distribution of encounters was maintained representing different health facilities. Forty seven percent of encounters involved children under 15 years of age. Female patients comprised of 56% and the mean age of the entire sample was 26 years. The mean dispensing time was only 38 seconds, the mean consultation time was 1.79 minutes and the average number of drugs per prescription turned out to be 2.7 out of which only 1.6 drugs were being dispensed from the facility. More than half of the prescriptions contained antibiotics and 15% of patients were prescribed with injectables. Only half of the patients expressed satisfaction with their visit to health facility.

CONCLUSIONS

Like many other developing countries, prescription and dispensing practices are not satisfactory in public sector health facilities of Pakistan. Appropriate and workable solutions need to be developed and implemented in the country to improve systems. Regular audits and qualitative studies should become part of the effort.

Spontaneous carotid artery dissection presenting as migraine--a diagnosis not to be missed

Two cases are reported in which the diagnosis of a serious condition was delayed as the symptoms had been attributed to migraine. Spontaneous carotid artery dissection is a serious but treatable cause of headache that may be misdiagnosed as recent onset migraine. The importance of correctly identifying this condition is emphasised.

Regulation of Ca(2+)-dependent nitric oxide synthase in bovine aortic endothelial cells

Vascular endothelium responds to Ca(2+)-mobilizing agonists by producing nitric oxide (NO), a potent vasodilator and inhibitor of platelet aggregation. Regulation of constitutively expressed endothelial NO synthase (eNOS) in intact cells is not well understood. We investigated the kinetics of NO formation in response to Ca(2+)-mobilizing agonists, the requirement for extracellular L-arginine, and the role of NO in regulating eNOS activity. When endothelial cells were stimulated with bradykinin and ATP in the presence of 100 microM L-arginine, we observed a rapid and transient rise in intracellular Ca2+ concentration ([Ca2+]i) from 50 +/- 8 nM to 698 +/- 74 and 637 +/- 53 nM, respectively, and a rapid and transient rise in NO production from a basal level of 37 pmol.min-1.mg protein-1 to 256 and 275 pmol.min-1.mg protein-1, respectively. When cells were stimulated with A-23187 or thapsigargin in the presence of 100 microM L-arginine, we observed a sustained increase in [Ca2+]i and a sustained increase in NO production. The rate of NO synthesis was linear over 30 min, rising above control levels of 7 pmol/min to 53 pmol/min for A-23187 and 62 pmol/min for thapsigargin. Thapsigargin stimulated NO production and [Ca2+]i with 50% effective concentration values of 0.01 and 0.05 microM, respectively. Ca(2+)-stimulated NO production was attenuated by the NO synthase inhibitor NG-monomethyl-L-arginine, the removal of extracellular L-arginine, and the Ca(2+)-chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. When we exposed cells to NO gas (3.1 mM for 15 min) and S-nitrosoglutathione (10 mM for 1 h) thapsigargin-stimulated NO production was decreased by 50%.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of hydrogen peroxide release from vascular endothelial cells by oxygen

We have investigated factors that regulate hydrogen peroxide (H2O2) release from vascular endothelial cells. Endothelial cells produce H2O2 at an intracellular site in the vicinity of peroxisomes and at a second site near the cell surface that is inaccessible to intracellular catalase or glutathione peroxidase. Regulation of H2O2 generation at the intracellular site was studied using aminotriazole, which inactivates catalase in the presence of H2O2. Regulation of H2O2 generation at the second site was studied by measuring H2O2 release into the medium. The rate of H2O2 release was constant over 2 h when cells were incubated in room air. Changing O2 levels in the atmosphere from 0% to 10% O2 resulted in a threefold increase in the rate of H2O2 release. Elevation of O2 levels from 10% to 95% O2 produced no further enhancement in the rate of release. Preincubation of cells under hypoxic conditions did not lead to an exaggerated rate of H2O2 release when cells were returned to room air. Pretreatment of cells with exogenous H2O2 inhibited subsequent H2O2 release while pretreatment with catalase enhanced H2O2 release. Although arachidonic acid transiently enhanced the rate of H2O2 release through a mechanism dependent on PGH synthase, basal H2O2 release was independent of this enzyme. Neither hypoxia, hyperoxia, or hypoxia followed by reoxygenation altered H2O2 generation at the intracellular site accessible to peroxisomal catalase. These data demonstrate that H2O2 release from endothelial cells is responsive to changes in O2 concentrations over a narrow range. The mechanisms involved are subject to product inhibition and appear to be saturated at 10% O2 in the atmosphere.

Effect of temperature on bradykinin-induced arachidonate release and calcium mobilization in vascular endothelial cells

The effect of decreased temperature on Ca(2+)-dependent arachidonic acid release was studied in vascular endothelial cells by investigating bradykinin (BK)-stimulated Ca2+ mobilization, inositol phosphate formation and arachidonic acid release. At both 37 degrees C and 22 degrees C, BK efficiently increased cytosolic Ca2+ concn. ([Ca2+]i). At 22 degrees C, peak [Ca2+]i was higher and returned to basal levels more slowly. Although this response was preceded by rapid formation of Ins(1,4,5)P3, the activity of phospholipase C was significantly impaired at 22 degrees C. To determine if Ins(1,4,5)P3 effectively mobilized intracellular Ca2+, we used saponin-permeabilized cells. Ins(1,4,5)P3, mobilized sequestered Ca2+ to a similar degree at 37 degrees C and 22 degrees C, although Ca2+ release was prolonged at 22 degrees C. In intact cells, BK mobilized intracellular Ca2+ stores and activated Ca2+ entry. The rate of 45Ca2+ entry was approx. 2-fold slower at 22 degrees C, even though the peak and duration of the rise in [Ca2+]i were higher and sustained at the lower temperature. TG mobilized intracellular Ca2+, activated Ca2+ entry and elevated [Ca2+]i at both temperatures. As with BK, the peak [Ca2+]i reached after thapsigargin treatment was higher at 22 degrees C. This effect of lower temperature on [Ca2+]i was most probably due to decreased Ca2+ efflux after a decrease in activity of the Ca(2+)-ATPase on the plasma membrane. Both A23187 and BK were shown to stimulate phospholipase A2 and arachidonic acid release at 22 degrees C. In each case, the rate and extent of release were decreased compared with that at 37 degrees C. Among several effects, lowering the temperature decreases the activity of phospholipase C, Ca(2+)-ATPase(s), Ca(2+)-entry mechanisms and phospholipase A2. Together, these effects lead to a higher and more prolonged elevation of [Ca2+]i, but a decrease in arachidonate release in response to BK.

Regulation of extracellular calcium entry in endothelial cells: role of intracellular calcium pool

We have investigated the role of the intracellular Ca2+ pool in regulating Ca2+ entry into vascular endothelial cells. The intracellular Ca2+ pool was mobilized using either thapsigargin (TG) or 2',5'-di(tert-butyl)-1,4-benzohydroquinone (BHQ), inhibitors of the endoplasmic reticulum Ca(2+)-adenosinetriphosphatase (ATPase). Mobilization of intracellular Ca2+ stores with either inhibitor depleted intracellular Ca2+ and greatly reduced subsequent mobilization of the inositol 1,4,5-trisphosphate (IP3)-sensitive intracellular Ca2+ pool by bradykinin. However, bradykinin-induced mobilization of the IP3-sensitive intracellular Ca2+ pool only partially reduced the subsequent response of cells to TG and BHQ. Mobilization of the intracellular Ca2+ pool by either TG or BHQ led to a concentration-dependent elevation of cytosolic Ca2+ concentrations ([Ca2+]i) without initiating inositol polyphosphate formation. In contrast to the rapidly developing, transient rise in Ca2+ concentration initiated by bradykinin, maximal concentrations of TG and BHQ stimulated a slowly developing, prolonged elevation of [Ca2+]i that required extracellular Ca2+ and could be blocked by extracellular Ni2+. Extracellular Ca2+ entered the cell through an activated cation entry pathway, since bradykinin, TG, and BHQ stimulated Mn2+ and 45Ca2+ entry. Bradykinin-stimulated 45Ca2+ uptake reached a peak within 2 min, whereas 45Ca2+ influx initiated by TG or BHQ continued for at least 8 min. Importantly, the [Ca2+]i response after low concentrations of BHQ was more transient than that seen after TG. The return of [Ca2+]i to basal values after low concentrations of BHQ was associated with reversal of Ca(2+)-ATPase inhibition and refilling of the IP3-sensitive Ca2+ pool. The continued elevation of [Ca2+]i and prolonged Ca2+ entry seen with TG was associated with continued Ca(2+)-ATPase inhibition and an empty IP3-sensitive Ca2+ pool. We conclude that mobilization of intracellular Ca2+ stores induces Ca2+ entry in endothelial cells which continues until the intracellular Ca2+ pool is refilled.

Modulation of oxidant lung injury by using liposome-entrapped superoxide dismutase and catalase

Increased cellular generation of partially reduced species of oxygen mediates the toxicity of hyperoxia to cultured endothelial cells and rats exposed to 95-100% oxygen. Liposomal entrapment and intracellular delivery of superoxide dismutase (SOD) to cultured porcine aortic endothelial cells increased the specific activity of cellular SOD up to 15-fold. The liposome-mediated augmentation of SOD activity persisted in cell monolayers and rendered these cells resistant to oxygen-induced injury in a cell SOD activity-dependent manner. Addition of free SOD to culture medium had no effect on cell SOD activity or resistance to oxygen toxicity. SOD and catalase-containing liposomes injected i.v. into rats increased lung-associated enzyme specific activities two- to fourfold. Liposome entrapment of both SOD and catalase significantly increased the circulating half-lives of these enzymes and was critical for prevention of in vivo oxygen toxicity. Free SOD and catalase injected i.v. in the absence or presence of control liposomes did not increase corresponding lung enzyme activities or survival time in 100% oxygen. These studies show that O2- and H2O2 are important mediators of oxygen toxicity and that intracellular delivery of oxygen protective enzymes can reduce tissue injury owing to overproduction of partially reduced oxygen species.