Naturally acquired CD8+ cytotoxic T lymphocytes against the Plasmodium falciparum circumsporozoite protein.

In rodent malaria model systems, protective immunity induced by immunization with irradiated sporozoites is eliminated by in vivo depletion of CD8+ T cells, and adoptive transfer of CTL clones against the circumsporozoite protein protects against malaria. We recently demonstrated that volunteers immunized with irradiated Plasmodium falciparum sporozoites produce CTL against peptide 368-390 of the P. falciparum circumsporozoite protein. To determine whether natural exposure to malaria induced similar CTL, we studied 11 adult, male, life-long residents of a highly malarious area of Kenya, who were selected because their lymphocytes had been shown to proliferate after stimulation with peptides 361-380, 371-390, or 368-390 and because nine had been resistant to malaria in previous studies. In four of the 11 individuals there was peptide-specific, genetically restricted, CTL activity. In all four individuals, this activity was unaffected by depletion of CD4+ T cells. In three volunteers the activity was eliminated or reduced by depletion of CD8+ T cells; in the fourth volunteer the CD8+ T cell depletion was uninterpretable. This first demonstration of CD8+ T cell, genetically restricted, Ag-specific CTL against a malaria protein among individuals exposed to endemic malaria provides a foundation for studying the relationship between circulating CTL and resistance to malaria infection.     

Ecological functioning in grass–shrub Mediterranean ecosystems measured by eddy covariance

Climate change may alter ecosystem functioning, as assessed via the net carbon (C) exchange (NEE) with the atmosphere, composed of the biological processes photosynthesis (GPP) and respiration (R _eco). In addition, in semi-arid Mediterranean ecosystems, a significant fraction of respired CO₂ is stored in the vadose zone and emitted afterwards by subsoil ventilation (VE), contributing also to NEE. Such conditions complicate the prediction of NEE for future change scenarios. To evaluate the possible effects of climate change on annual NEE and its underlying processes (GPP, R _eco and VE) we present, over a climate/altitude range, the annual and interannual variability of NEE, GPP, R _eco and VE in three Mediterranean sites. We found that annual NEE varied from a net source of around 130 gC m^?2 in hot and arid lowlands to a net sink of similar magnitude for alpine meadows (above 2,000 m a.s.l) that are less water stressed. Annual net C fixation increased because of increased GPP during intermittent and several growth periods occurring even during winter, as well as due to decreased VE. In terms of interannual variability, the studied subalpine site behaved as a neutral C sink (from emission of 49 to fixation of 30 gC m^?2 year^?1), with precipitation as the main factor controlling annual GPP and R _eco. Finally, the importance of VE as 0–23 % of annual NEE is highlighted, indicating that this process could shift some Mediterranean ecosystems from annual C sinks to sources.     

Severe malarial anemia: innate immunity and pathogenesis

Greater than 80% of malaria-related mortality occurs in sub-Saharan Africa due to infections with Plasmodium falciparum. The majority of P. falciparum-related mortality occurs in immune-naïve infants and young children, accounting for 18% of all deaths before five years of age. Clinical manifestations of severe falciparum malaria vary according to transmission intensity and typically present as one or more life-threatening complications, including: hyperparasitemia; hypoglycemia; cerebral malaria; severe malarial anemia (SMA); and respiratory distress. In holoendemic transmission areas, SMA is the primary clinical manifestation of severe childhood malaria, with cerebral malaria occurring only in rare cases. Mortality rates from SMA can exceed 30% in pediatric populations residing in holoendemic transmission areas. Since the vast majority of the morbidity and mortality occurs in immune-naïve African children less than five years of age, with SMA as the primary manifestation of severe disease, this review will focus primarily on the innate immune mechanisms that govern malaria pathogenesis in this group of individuals. The pathophysiological processes that contribute to SMA involve direct and indirect destruction of parasitized and non-parasitized red blood cells (RBCs), inefficient and/or suppression of erythropoiesis, and dyserythropoiesis. While all of these causal etiologies may contribute to reduced hemoglobin (Hb) concentrations in malaria-infected individuals, data from our laboratory and others suggest that SMA in immune-naïve children is characterized by a reduced erythropoietic response. One important cause of impaired erythroid responses in children with SMA is dysregulation in the innate immune response. Phagocytosis of malarial pigment hemozoin (Hz) by monocytes, macrophages, and neutrophils is a central factor for promoting dysregulation in innate inflammatory mediators. As such, the role of P. falciparum-derived Hz (PfHz) in mediating suppression of erythropoiesis through its ability to cause dysregulation in pro- and anti-inflammatory cytokines, growth factors, chemokines, and effector molecules is discussed in detail. An improved understanding of the etiological basis of suppression of erythropoietic responses in children with SMA may offer the much needed therapeutic alternatives for control of this global disease burden.     

THINKING THROUGH IMAGES: KASTOM AND THE COMING OF THE BAHA'IS TO NORTHERN NEW IRELAND, PAPUA NEW GUINEA

We can learn a lot about religious ideas by studying not just the impact on them of missionization but also how religious beliefs and practices are translated into local religious forms. In this article I draw attention to the case of the Baha'i faith in the Nalik area of northern New Ireland (Papua New Guinea). In discussing how the faith became strongly associated with the ability to harness ancestral power, I argue that this relationship emerged through Nalik people's ability to think through images, in other words through transforming forms in order to create new understandings. This study not only underlines the importance of localized studies into the technology of image production but also fills a gap in anthropological studies that, up until now, have systematically ignored the Baha'i movement and its place in the contemporary Pacific.     

Effect of newborn resuscitation training on health worker practices in Pumwani Hospital, Kenya

Background

Birth asphyxia kills 0.7 to 1.6 million newborns a year globally with 99% of deaths in developing countries. Effective newborn resuscitation could reduce this burden of disease but the training of health-care providers in low income settings is often outdated. Our aim was to determine if a simple one day newborn resuscitation training (NRT) alters health worker resuscitation practices in a public hospital setting in Kenya.

Methods/Principal Findings

We conducted a randomised, controlled trial with health workers receiving early training with NRT (n = 28) or late training (the control group, n = 55). The training was adapted locally from the approach of the UK Resuscitation Council. The primary outcome was the proportion of appropriate initial resuscitation steps with the frequency of inappropriate practices as a secondary outcome. Data were collected on 97 and 115 resuscitation episodes over 7 weeks after early training in the intervention and control groups respectively. Trained providers demonstrated a higher proportion of adequate initial resuscitation steps compared to the control group (trained 66% vs control 27%; risk ratio 2.45, [95% CI 1.75–3.42], p<0.001, adjusted for clustering). In addition, there was a statistically significant reduction in the frequency of inappropriate and potentially harmful practices per resuscitation in the trained group (trained 0.53 vs control 0.92; mean difference 0.40, [95% CI 0.13–0.66], p = 0.004).

Conclusions/Significance

Implementation of a simple, one day newborn resuscitation training can be followed immediately by significant improvement in health workers'' practices. However, evidence of the effects on long term performance or clinical outcomes can only be established by larger cluster randomised trials.

Trial Registration

Controlled-Trials.com ISRCTN92218092     

Wind as a main driver of the net ecosystem carbon balance of a semiarid Mediterranean steppe in the South East of Spain

Despite the advance in our understanding of the carbon exchange between terrestrial ecosystems and the atmosphere, semiarid ecosystems have been poorly investigated and little is known about their role in the global carbon balance. We used eddy covariance measurements to determine the exchange of CO₂ between a semiarid steppe and the atmosphere over 3 years. The vegetation is a perennial grassland of Stipa tenacissima L. located in the SE of Spain. We examined diurnal, seasonal and interannual variations in the net ecosystem carbon balance (NECB) in relation to biophysical variables. Cumulative NECB was a net source of 65.7, 143.6 and 92.1 g C m^?2 yr^?1 for the 3 years studied, respectively. We separated the year into two distinctive periods: dry period and growing season. The ecosystem was a net source of CO₂ to the atmosphere, particularly during the dry period when large CO₂ positive fluxes of up to 15 μmol m^?2 s^?1 were observed in concomitance with large wind speeds. Over the growing season, the ecosystem was a slight sink or neutral with maximum rates of ?2.3 μmol m^?2 s^?1. Rainfall events caused large fluxes of CO₂ to the atmosphere and determined the length of the growing season. In this season, photosynthetic photon flux density controlled day‐time NECB just below 1000 μmol m^?2 s^?1. The analyses of the diurnal and seasonal data and preliminary geological and gas‐geochemical evaluations, including C isotopic analyses, suggest that the CO₂ released was not only biogenic but most likely included a component of geothermal origin, presumably related to deep fluids occurring in the area. These results highlight the importance of considering geological carbon sources, as well as the need to carefully interpret the results of eddy covariance partitioning techniques when applied in geologically active areas potentially affected by CO₂‐rich geofluid circulation.     

Determinants of teenage pregnancies: The case of Busia District in Kenya

Sub-Saharan Africa has one of the highest levels of teenage pregnancies in the world. In spite of that, there is paucity of empirical research on causes of teenage pregnancies in African countries. This paper investigates the determinants of teenage pregnancies based on a case study of Busia District in Kenya. The data are from a household survey conducted in 1998/1999. Empirical results indicate that girls' education level has significant influence on the probability of teenage birth, with non-schooling adolescents and those with primary school level education being more vulnerable. Among the variables used as proxies for access to sex education, availability of church forums that educate adolescents about sex and family life issues reduce probability of teenage pregnancy. Age is positively related to teenage pregnancies, with older adolescents being more predisposed to pregnancies. Though use of contraceptives is found to have a positive effect, only a small proportion of adolescents were using modern contraceptives and, supply side factors such as quality and availability were not accounted for. Other key factors as outlined by the adolescents themselves include peer pressure and social environment-related factors like inappropriate forms of recreation, which act as rendezvous for pre-marital sex, as well as lack of parental guidance and counselling. Overall, lack of access to education opportunities, sex education and information regarding contraceptives, as well the widespread poverty predispose girls to teenage pregnancies. The problem of teenage pregnancies should be viewed within the broader socio-economic and socio-cultural environment in which the adolescents operate. For instance, lack of parental guidance on issues of sexuality and sex education was reinforced by cultural taboos that inhibit such discussions. Adolescents should be equipped with the relevant knowledge to enable them make informed choices regarding sexual relationships. This should be complemented with broader programmes aimed at promoting girl education and poverty alleviation.