Evidence and practice: the magnesium sulphate story

Feasibility of task-sharing with community health workers for the identification, emergency management and referral of women with pre-eclampsia, in Mozambique

Background

Maternal mortality is an important public health problem in low-income countries. Delays in reaching health facilities and insufficient health care professionals call for innovative community-level solutions. There is limited evidence on the role of community health workers in the management of pregnancy complications. This study aimed to describe the feasibility of task-sharing the initial screening and initiation of obstetric emergency care for pre-eclampsia/eclampsia from the primary healthcare providers to community health workers in Mozambique and document healthcare facility preparedness to respond to referrals.

Method

The study took place in Maputo and Gaza Provinces in southern Mozambique and aimed to inform the Community-Level Interventions for Pre-eclampsia (CLIP) cluster randomized controlled trial. This was a mixed-methods study. The quantitative data was collected through self-administered questionnaires completed by community health workers and a health facility survey; this data was analysed using Stata v13. The qualitative data was collected through focus group discussions and in-depth interviews with various community groups, health care providers, and policymakers. All discussions were audio-recorded and transcribed verbatim prior to thematic analysis using QSR NVivo 10. Data collection was complemented by reviewing existing documents regarding maternal health and community health worker policies, guidelines, reports and manuals.

Results

Community health workers in Mozambique were trained to identify the basic danger signs of pregnancy; however, they have not been trained to manage obstetric emergencies. Furthermore, barriers at health facilities were identified, including lack of equipment, shortage of supervisors, and irregular drug availability. All primary and the majority of secondary-level facilities (57%) do not provide blood transfusions or have surgical capacity, and thus such cases must be referred to the tertiary-level. Although most healthcare facilities (96%) had access to an ambulance for referrals, no transport was available from the community to the healthcare facility.

Conclusions

This study showed that task-sharing for screening and pre-referral management of pre-eclampsia and eclampsia were deemed feasible and acceptable at the community-level, but an effort should be in place to address challenges at the health system level.

Maternal mortality is an important public health problem in Mozambique. Delays in reaching health facilities and insufficient health care professionals call for innovative community-level solutions. We conducted a study to describe the feasibility of task-sharing the screening and initiation of management for pre-eclampsia/eclampsia from the primary healthcare providers to community health workers in Mozambique and to document healthcare facility preparedness to respond to referrals. The study was done to inform a future intervention trial known as the Community-Level Interventions for Pre-eclampsia (CLIP) study. We interviewed community health workers, women, various community groups, health care providers, and policymakers and assessed health facilities in Maputo and Gaza provinces, Mozambique. Our results showed that community health workers in Mozambique were trained to identify the basic danger signs of pregnancy; however, they were not trained or equipped to provide obstetric emergencies care prior to referral. Nurses at primary health facilities were supportive of task-sharing with community health workers; however, some barriers mentioned include a lack of equipment, shortage of supervisors, and irregular drug availability. Local stakeholders emphasized the need for comprehensive training and supervision of community health workers to take on new tasks. Task-sharing for screening and pre-referral management of pre-eclampsia and eclampsia was deemed feasible at the community level in southern Mozambique, but still, to be addressed some health system level barriers to the management of pregnancies complications.

Clinical features and outcomes of pregnancies complicated by pre-ecplampsia necessitating in-utero transfer

OBJECTIVES

Pre-eclampsia (PE) is associated with significant risks of adverse perinatal outcomes, often necessitating transfer to a higher level of care for specialist perinatal management. In Victoria, Australia, the Paediatric Infant Perinatal Emergency Retrieval (PIPER) coordinates in-utero transfers of high-risk pregnancies. Our objectives were to report the clinical features and outcomes of women referred to PIPER with a primary diagnosis of PE, and subsequently transferred in-utero.

STUDY DESIGN

A retrospective audit of consecutive pregnancies referred to PIPER in 2013-2014 with a primary diagnosis of pre-eclampsia, ≥20 weeks' gestation and transferred in-utero.

MAIN OUTCOME MEASURES

Severity of disease, gestational age, transfer details and outcome until 7 days post transfer.

RESULTS

Over two years, 244 women were referred to PIPER with PE; 199 (82%) were subsequently transferred in-utero. Severe PE was diagnosed in 146 (73%) women. Overall, 64% presented 'early' (<32 weeks' gestation). Only 6% were ≥37 weeks. All but 2 women <32 weeks were transferred to a tertiary perinatal centre, compared with 39% of women ≥32 weeks. Within 7 days, 153/199 (77%) delivered, 10% remained in-patients and 12.5% were discharged. There were 165 livebirths and 3 stillbirths, with a mean gestational age of 30.7 weeks (SD 3.3 weeks). Twenty-nine women required high dependency or intensive care admission. No maternal deaths were reported.

CONCLUSION

Women referred to PIPER predominantly presented with early onset, severe PE and most delivered within 7 days of transfer. Data from this study provides important information for obstetric service planning in Victoria and comparable regions.

Systematic review to identify proxy indicators to quantify the impact of eHealth tools on maternal and neonatal health outcomes in low-income and middle-income countries including Delphi consensus

OBJECTIVE

To identify interventions that could serve as reliable proxy indicators to measure eHealth impact on maternal and neonatal outcomes.

DESIGN

Systematic review and Delphi study.

METHODS

We searched PubMed, Embase and Cochrane from January 1990 to May 2016 for studies and reviews that evaluated interventions aimed at improving maternal/neonatal health and reducing mortality. Interventions that are not low-income and middle-income context appropriate and that cannot currently be diagnosed, managed or impacted by eHealth (eg, via telemedicine distance diagnostic or e-learning) were excluded. We used the Cochrane risk of bias, Risk Of Bias In Non- randomised Studies - of Interventions and ROBIS tool to assess the risk of bias. A three-step modified Delphi method was added to identify additional proxy indicators and prioritise the results, involving a panel of 13 experts from different regions, representing obstetricians and neonatologists.

RESULTS

We included 44 studies and reviews, identifying 40 potential proxy indicators with a positive impact on maternal/neonatal outcomes. The Delphi experts completed and prioritised these, resulting in a list of 77 potential proxy indicators.

CONCLUSIONS

The proxy indicators propose relevant outcome measures to evaluate if eHealth tools directly affect maternal/neonatal outcomes. Some proxy indicators require mapping to the local context, practices and available resources. The local mapping facilitates the utilisation of the proxy indicators in various contexts while allowing the systematic collection of data from different projects and programmes. Based on the mapping, the same proxy indicator can be used for different contexts, allowing it to measure what is locally and temporally relevant, making the proxy indicator sustainable.

PROSPERO REGISTRATION NUMBER

CRD42015027351.

A Dormant Microbial Component in the Development of Preeclampsia

Preeclampsia (PE) is a complex, multisystem disorder that remains a leading cause of morbidity and mortality in pregnancy. Four main classes of dysregulation accompany PE and are widely considered to contribute to its severity. These are abnormal trophoblast invasion of the placenta, anti-angiogenic responses, oxidative stress, and inflammation. What is lacking, however, is an explanation of how these themselves are caused. We here develop the unifying idea, and the considerable evidence for it, that the originating cause of PE (and of the four classes of dysregulation) is, in fact, microbial infection, that most such microbes are dormant and hence resist detection by conventional (replication-dependent) microbiology, and that by occasional resuscitation and growth it is they that are responsible for all the observable sequelae, including the continuing, chronic inflammation. In particular, bacterial products such as lipopolysaccharide (LPS), also known as endotoxin, are well known as highly inflammagenic and stimulate an innate (and possibly trained) immune response that exacerbates the inflammation further. The known need of microbes for free iron can explain the iron dysregulation that accompanies PE. We describe the main routes of infection (gut, oral, and urinary tract infection) and the regularly observed presence of microbes in placental and other tissues in PE. Every known proteomic biomarker of "preeclampsia" that we assessed has, in fact, also been shown to be raised in response to infection. An infectious component to PE fulfills the Bradford Hill criteria for ascribing a disease to an environmental cause and suggests a number of treatments, some of which have, in fact, been shown to be successful. PE was classically referred to as endotoxemia or toxemia of pregnancy, and it is ironic that it seems that LPS and other microbial endotoxins really are involved. Overall, the recognition of an infectious component in the etiology of PE mirrors that for ulcers and other diseases that were previously considered to lack one.

Survey of calcium supplementation to prevent preeclampsia: the gap between evidence and practice in Brazil

BACKGROUND

Preeclampsia is a major cause of maternal and perinatal morbidity and mortality worldwide and especially in Latin America. High quality evidence indicates that calcium supplementation during pregnancy significantly reduces the incidence of preeclampsia and its consequences, including severe maternal morbidity and death. Few studies have assessed the implementation of this intervention in clinical practice. The study aimed to assess the proportion of pregnant women who received calcium supplements in Brazilian public antenatal care clinics.

METHODS

This cross-sectional study interviewed women waiting for antenatal care visits in 9 public clinics in 4 Brazilian cities in 2010-2012. Trained interviewers used a standardized anonymous questionnaire to collect socio demographic and obstetric data, information on ingestion of dairy products and on prescriptions received during current pregnancy.

RESULTS

A total of 788 valid questionnaires were analyzed. Participants were young (mean age 25.9), mostly multiparous (71.3%) and in the 2nd or 3rd trimesters of pregnancy at the time of interview (87.6%). Only 5.1% (40/788) had received a prescription for calcium supplements. Based on their reported ingestion of dairy products, the mean daily dietary calcium intake of the participants was 210 (+ 265) mg/day and over 90% consumed less than 1 g of calcium/day.

CONCLUSIONS

Despite good quality evidence indicating the benefits of this practice especially for women with low calcium diets, less than 6% of a sample of women receiving antenatal care in Brazilian public clinics received a prescription for calcium supplements. There is an urgent need to upscale the implementation of this life-saving intervention.

[Magnesium sulfate in the prophylaxis of eclampsia: a retrospective study]

INTRODUCTION

The use of magnesium sulfate (MgSO(4)) has been advocated since 2000 in France in the management of eclampsia. The aim of this study was to determine the frequency of use of this treatment for eclampsia in a French department.

PATIENTS AND METHODS

All patients obstetrical patients admitted to Critical Care Units of Seine-Maritime for eclampsia over a period of 7 years (2002-2008) were included. Obstetric data, the treatment used for eclampsia and pre-eclampsia and maternofetal complications were collected. The primary outcome parameter was the use of MgSO(4) in the secondary prevention of eclampsia.

RESULTS

Thirty-nine patients were included. Nineteen patients (48%) had eclampsia in prepartum, three (8%) in per-partum and 17 (44%) in post-partum periods. The use of MgSO(4) in the secondary prevention of eclampsia was observed in 92% of cases (36/39). Primary prevention was seen in 8% of cases. The duration of treatment was 2 days (1-7 days). The maternal and perinatal mortality was respectively 2.5 and 11%.

CONCLUSION

In this study, the use of MgSO(4) in the secondary prevention is frequent. This result emphasizes the importance of the recommendations of learned societies in the homogenization of the management of rare but serious conditions such as eclampsia.

[Use of magnesium sulfate in obstetrics]

Magnesium sulfate (MgSO(4)) is the best treatment of eclampsia, reduces the risk of recurrence better than other anticonvulsants and is recommended as first line in cases of eclampsia. In cases of severe pre-eclampsia and especially when prodromes are present, MgSO(4) reduces better than conventional anticonvulsants the risk of eclampsia. More recently, MgSO(4) was used in cases of preterm delivery to reduce the risk of cerebral palsy in premature infants. Three large randomized trials have obtained convergent results which all tended to show a neuroprotective effect of MgSO(4). These trials were included in three meta-analyzes that showed a 30% reduction in the incidence of cerebral palsy before 32 weeks gestation suggesting that this drug should be used in cases of preterm birth. A protocol using low doses associated with a well-conducted maternal surveillance reduces of maternal hypermagnesemia and the risk of maternal toxicity.

Disease burden due to pre-eclampsia/eclampsia and the Ethiopian health system's response

OBJECTIVE

To assess the maternal disease burden due to pre-eclampsia/eclampsia in Ethiopia and the national health system's readiness to respond to the needs of women with pre-eclampsia/eclampsia.

METHODS

The national emergency obstetric and newborn care (EmONC) assessment entailed collecting information from 112 hospitals and 685 health centers in Ethiopia, focusing on their infrastructure, the services they provided, human resources, equipment and supplies, case load, and mortality due to pre-eclampsia/eclampsia.

RESULTS

Pre-eclampsia/eclampsia complicated 1.2% of all institutional deliveries. Given the low institutional delivery rate and an expected incidence of 2%-8% of all deliveries, this implies that only a small fraction (3.8%) of all women with pre-eclampsia/eclampsia received care at health facilities. 11% of all maternal deaths and 16% of direct maternal deaths were due to this obstetric complication. The cause-specific case fatality rate was high (3.6%). Availability of urine test strips, anticonvulsants, antihypertensives, and actual service provision to treat these diseases was limited, especially at health centers.

CONCLUSION

The salutary effects of the national EmONC assessment were immediate, as evidenced by how quickly the release of the Ethiopian report led to important national efforts to improve maternal and newborn health. Expansion of health services should be augmented with periodic assessments of logistics and quality-related issues to assure functioning facilities for women accessing obstetric services.

The growth of a culture of evidence-based obstetrics in South Africa: a qualitative case study

BACKGROUND

While the past two decades have seen a shift towards evidence-based obstetrics and midwifery, the process through which a culture of evidence-based practice develops and is sustained within particular fields of clinical practice has not been well documented, particularly in LMICs (low- and middle-income countries). Forming part of a broader qualitative study of evidence-based policy making, this paper describes the development of a culture of evidence-based practice amongst maternal health policy makers and senior academic obstetricians in South Africa.

METHODS

A qualitative case-study approach was used. This included a literature review, a policy document review, a timeline of key events and the collection and analysis of 15 interviews with policy makers and academic clinicians involved in these policy processes and sampled using a purposive approach. The data was analysed thematically.

RESULTS

The concept of evidence-based medicine became embedded in South African academic obstetrics at a very early stage in relation to the development of the concept internationally. The diffusion of this concept into local academic obstetrics was facilitated by contact and exchange between local academic obstetricians, opinion leaders in international research and structures promoting evidence-based practice. Furthermore the growing acceptance of the concept was stimulated locally through the use of existing professional networks and meetings to share ideas and the contribution of local researchers to building the evidence base for obstetrics both locally and internationally. As a testimony to the extent of the diffusion of evidence-based medicine, South Africa has strongly evidence-based policies for maternal health.

CONCLUSION

This case study shows that the combined efforts of local and international researchers can create a culture of evidence-based medicine within one country. It also shows that doing so required time and perseverance from international researchers combined with a readiness by local researchers to receive and actively promote the practice.

[Sixty-nine consecutive cases of eclampsia: prodromes and circumstances]

OBJECTIVE

To specify clinical and biological characteristics of patients developing eclampsia, and identify atypical eclampsia without prior signs and symptoms of severe preeclampsia.

PATIENTS AND METHODS

This was a retrospective observational study conducted from January 1996 to December 2008 in a maternity type IIB in French Guiana. Data of patients who experienced eclampsia were collected from obstetric records.

RESULTS

Sixty-nine patients were selected among 21,525 patients who delivered during this period, corresponding to a prevalence of 3.2 ‰. The average patient age was 21 years (range from 12 to 45 years). Sixty-six percent of patients were nulliparous. The gestational age was greater than 37 weeks of gestation for 62% of patients, between 26 and 37 weeks of gestation for 36% and less than 26 weeks of gestation for 2% of patients. Two thirds of the patients had been examined less than a month before the eclamptic seizure, blood pressure was normal in 62% of cases. Seventy-four percent of patients had at least one Doppler study of the uterine and umbilical arteries velocimetry, the Dopplers studies were normal in 78% of cases. The eclampsia occurred in ante-, peri- and post-partum in 59, 6 and 35% of the cases, respectively 10% of patients were hospitalized for preeclampsia at the time of eclamptic seizure. Less than 10% of patients developed HELLP syndrome. One patient had died of aspiration pneumonia. Newborns had a mean birth weight over 2500 g in 88% of cases. During the follow-up period, 41% of the patients had subsequent pregnancies with 62% without hypertension, 24% complicated by recurrent gestational hypertension, 24% by preeclampsia and 4% by eclampsia.

DISCUSSION AND CONCLUSION

In a majority of the patients in our study, eclampsia was the main manifestation, and only 10% were preceded by severe preeclampsia. These results are comparable to recent studies, which found in their series that 40 to 60% of eclampsia manifested without preeclamptic prodromi. Eclampsia can occur after an unremarkable pregnancy, in women without risk factors, and then it is hardly predictable. Prenatal follow-up must be very cautious paying attention to any markers such as intermittent hypertension, functional symptoms or appearance of proteinuria.

Effects of combined vanadate and magnesium treatment on erythrocyte antioxidant defence system in rats

The effect of vanadate and magnesium treatment on erythrocyte defence system was studied in outbred 2-month-old, albino male Wistar rats (14 rats/each group) which daily received: Group I (Control)-deionized water to drink; Group II-water solution of sodium metavanadate (NaVO(3); SMV) at a concentration of 0.125mgV/mL; Group III-water solution of magnesium sulfate (MgSO(4); MS) at a concentration of 0.06mgMg/mL, Group IV-water solution of SMV-MS at the same concentrations over a 12-week time. The fluid intake and the concentration of reduced glutathione (GSH) as well as the activity of Cu, Zn-superoxide dismutase (Cu, Zn-SOD), catalase (CAT) and glutathione reductase (GR) were significantly decreased in the rats receiving SMV alone (Group II) or in combination with MS (Group IV) compared with Groups I and III. The cellular glutathione peroxidase (cGSH-Px) activity was unchanged in all the treated groups. The activity of glutathione S-transferase (GST) fell in the animals in Group II, compared with the rats in Groups I, III and IV; whereas in the rats in Group III its activity was higher than in the control animals. These results showed that V (as SMV) consumed by the rats with drinking water at a dose of 12mgV/kg b.w./24h for 12 weeks may attenuate defence system in rats' erythrocytes (RBCs), which is probably a consequence of vanadium pro-oxidant potential. Therefore, reactive oxygen species (ROS) are suggested to be involved in the alterations in antioxidant defence system in these cells. Mg (as MS) at the dose ingested (6mgMg/kg b.w./24h) at co-exposure to SMV was not able to counteract its deleterious effect. The results also provide evidence that V-Mg interactions may be involved in the decrease of erythrocyte GR activity and Mg concentration in the plasma under concomitant treatment with both metals at the doses of 12.6mgV and 6mgMg/kg b.w./24h.

Translating research into policy: lessons learned from eclampsia treatment and malaria control in three southern African countries

BACKGROUND

Little is known about the process of knowledge translation in low- and middle-income countries. We studied policymaking processes in Mozambique, South Africa and Zimbabwe to understand the factors affecting the use of research evidence in national policy development, with a particular focus on the findings from randomized control trials (RCTs). We examined two cases: the use of magnesium sulphate (MgSO(4)) in the treatment of eclampsia in pregnancy (a clinical case); and the use of insecticide treated bed nets and indoor residual household spraying for malaria vector control (a public health case).

METHODS

We used a qualitative case-study methodology to explore the policy making process. We carried out key informants interviews with a range of research and policy stakeholders in each country, reviewed documents and developed timelines of key events. Using an iterative approach, we undertook a thematic analysis of the data.

FINDINGS

Prior experience of particular interventions, local champions, stakeholders and international networks, and the involvement of researchers in policy development were important in knowledge translation for both case studies. Key differences across the two case studies included the nature of the evidence, with clear evidence of efficacy for MgSO(4 )and ongoing debate regarding the efficacy of bed nets compared with spraying; local researcher involvement in international evidence production, which was stronger for MgSO(4 )than for malaria vector control; and a long-standing culture of evidence-based health care within obstetrics. Other differences were the importance of bureaucratic processes for clinical regulatory approval of MgSO(4), and regional networks and political interests for malaria control. In contrast to treatment policies for eclampsia, a diverse group of stakeholders with varied interests, differing in their use and interpretation of evidence, was involved in malaria policy decisions in the three countries.

CONCLUSION

Translating research knowledge into policy is a complex and context sensitive process. Researchers aiming to enhance knowledge translation need to be aware of factors influencing the demand for different types of research; interact and work closely with key policy stakeholders, networks and local champions; and acknowledge the roles of important interest groups.

Impaired migration signaling in the hippocampus following prenatal hypoxia

Prenatal hypoxia ischemia is a major cause of neurodevelopmental impairment in the newborn, associated with risk for motor, behavioral and cognitive impaired outcomes. We used an established mouse model of maternal hypoxia to examine the immediate molecular responses of signaling pathways associated with both cell death and neurogenesis. We also characterized responses to maternal pre-treatment with MgSO(4). Maternal hypoxia at embryonic day 17 (E17) failed to trigger inflammation or cell death in fetal brain at 24 h after hypoxia. However, maternal hypoxia decreased levels of neuronal migration signaling: Reelin (53% of control), Disabled 1 (Dab1, 77% of control), and amyloid precursor protein (APP, 64% of control) 2 h after the insult. These changes persisted for 24 h. At later times, Reelin levels in hippocampi of newborns in the maternal hypoxia-treated group increased compared to controls. Full protection from maternal hypoxia effects on hippocampal Reelin levels resulted from maternal pre-treatment with MgSO(4). Hypoxia and MgSO(4) increased radial and lateral migration distance in the CA1 four days after the insult, while in the DG the hypoxia treatment alone increased migration. Maternal hypoxia and MgSO(4) pre-treatment also stimulated hippocampal expression of genes related to neurogenesis, such as BDNF and NeuroD4. Taken together, the long-term neurodevelopmental outcome of prenatal and perinatal hypoxia may depend on perturbation of developmental signals that affect neuronal migration.

Combined magnesium and mild hypothermia (35 degrees C) treatment reduces infarct volumes after permanent middle cerebral artery occlusion in the rat at 2 and 4, but not 6 h

BACKGROUND AND PURPOSE

Using transient focal and global cerebral ischemia models in the rat, we have previously shown that MgSO4 is not neuroprotective unless it is combined with mild hypothermia. This study establishes a therapeutic time window for combined MgSO4 and mild hypothermia treatment after permanent middle cerebral artery occlusion (MCAO).

METHODS

Rats were subjected to permanent intraluminal thread MCAO and animals were treated 2, 4 or 6 h after ischemia with a MgSO4 infusion (360 micromol/kg, then 120 micromol/kg/h) and mild hypothermia (35 degrees C) or with vehicle for 24 h. At the 2 h time point, treatment with hypothermia alone and MgSO4 alone were also assessed. Infarct volumes were measured 48 h after MCAO induction.

RESULTS

After permanent MCAO, combined MgSO4 and hypothermia treatment reduced infarct volumes by 54% at 2 h (P = 0.048) and by 39% at 4 h (P = 0.012), but there was no treatment effect detected at 6 h or in the hypothermia alone or MgSO4 alone groups.

CONCLUSIONS

These findings support our earlier work highlighting the neuroprotective effect of MgSO4 when combined with mild hypothermia, even when treatment is delayed by several hours.

Factors influencing the postpartum length of hospital stay in eclamptic women

OBJECTIVE

To determine which variables are associated with postpartum length of hospital stay in eclamptic patients.

MATERIALS AND METHODS

The study sample comprised 98 eclamptic patients who were admitted to our perinatology unit during the period between January 1998 and May 2003. The study sample was divided into two postpartum length-of-stay groups: the short-stay group (1-3 days) consisted of 33 patients and the long-stay group (4 days and longer) consisted of 65 patients. The groups were compared with respect to the demographic characteristics, clinical and laboratory variables, and complications.

RESULTS

The mean hospitalization periods for the short-stay and long-stay groups were 2.48 +/- 0.79 and 5.60 +/- 2.12 days, respectively ( p = 0.010). The mean prepartum follow-up period after the onset of eclampsia was longer in the long-stay group than in the short-stay group (12.11 +/- 27.63 vs. 5.08 +/- 6.08 hours). The proportion of patients receiving magnesium sulfate therapy longer than 12 hours was higher in the long-stay group ( p = 0.014). The long-stay group had higher diastolic arterial blood pressure than that of the short-stay group ( p = 0.006). The total cesarean delivery rate for the short-stay group was 48.5%, compared with 67.7% in the long-stay group ( p = 0.081).

CONCLUSION

The duration of magnesium therapy, the timing, and the mode of delivery should be individualized to reduce the length of hospital stay in eclamptic patients.

Role of Cav1.2 L-type Ca2+ channels in vascular tone: effects of nifedipine and Mg2+

Ca(2+) entry via L-type voltage-gated Ca(2+) channels (LVGCs) is a key factor in generating myogenic tone (MT), as dihydropyridines (DHPs) and other LVGC blockers, including Mg(2+), markedly reduce MT. Recent reports suggest, however, that elevated external Mg(2+) concentration and DHPs may also inhibit other Ca(2+)-entry pathways. Here, we explore the contribution of LVGCs to MT in intact, pressurized mesenteric small arteries using mutant mice (DHP(R/R)) expressing functional but DHP-insensitive Ca(v)1.2 channels. In wild-type (WT), but not DHP(R/R), mouse arteries, nifedipine (0.3-1.0 microM) markedly reduced MT and vasoconstriction induced by high external K(+) concentrations ([K(+)](o)), a measure of LVGC-mediated Ca(2+) entry. Blocking MT and high [K(+)](o)-induced vasoconstriction by <1 microM nifedipine in WT but not in DHP(R/R) arteries implies that Ca(2+) entry via Ca(v)1.2 LVGCs is obligatory for MT and that nifedipine inhibits MT exclusively by blocking LVGCs. We also examined the effects of Mg(2+) on MT and LVGCs. High external Mg(2+) concentration (10 mM) blocked MT, slowed the high [K(+)](o)-induced vasoconstrictions, and decreased their amplitude in WT and DHP(R/R) arteries. To verify that these effects of Mg(2+) are due to block of LVGCs, we characterized the effects of extracellular and intracellular Mg(2+) on LVGC currents in isolated mesenteric artery myocytes. DHP-sensitive LVGC currents are inhibited by both external and internal Mg(2+). The results indicate that Mg(2+) relaxes MT by inhibiting Ca(2+) influx through LVGCs. These data provide new information about the central role of Ca(v)1.2 LVGCs in generating and maintaining MT in mouse mesenteric small arteries.

A review of the management of eclampsia: practical issues

We reviewed 90 cases of eclampsia, an obstetric emergency associated with high blood pressure and convulsions, treated in two hospitals in Durban, South Africa. We present a protocol for the management of eclampsia based on this review and extensive clinical experience on this subject, which includes hemodynamic stabilization of the mother, prevention of recurrent convulsions, prompt delivery, and intensive monitoring in the immediate post-partum period.