Different types of sensation seeking

Previous research on sensation seeking (SS) was dominated by a variable-oriented approach indicating that SS level has a linear relation with a host of problem behaviors. Our aim was to provide a person-oriented methodology—a probabilistic clustering—that enables examination of both inter- and intra-individual differences in not only the level, but also in the pattern of SS. We have applied model-based clustering to a four-semester long longitudinal high school survey ( N = 3334) and to a cross-sectional university survey ( N = 438). The results indicated that impulsive patterns are linked to negative outcomes whereas non-impulsive patterns are associated with positive outcomes. Our study aims to serve as a methodological example on how to apply model-based clustering to examine different types of sensation-seeking patterns. This modern clustering method allows for probabilistic categorization, with continous typicality scores besides cluster membership variables. These typicality scores turned out to have higher temporal stability than simple categorical membership variables did.

Feedback-based, system-level properties of vertebrate-microbial interactions

Background

Improved characterization of infectious disease dynamics is required. To that end, three-dimensional (3D) data analysis of feedback-like processes may be considered.

Methods

To detect infectious disease data patterns, a systems biology (SB) and evolutionary biology (EB) approach was evaluated, which utilizes leukocyte data structures designed to diminish data variability and enhance discrimination. Using data collected from one avian and two mammalian (human and bovine) species infected with viral, parasite, or bacterial agents (both sensitive and resistant to antimicrobials), four data structures were explored: (i) counts or percentages of a single leukocyte type, such as lymphocytes, neutrophils, or macrophages (the classic approach), and three levels of the SB/EB approach, which assessed (ii) 2D, (iii) 3D, and (iv) multi-dimensional (rotating 3D) host-microbial interactions.

Results

In all studies, no classic data structure discriminated disease-positive (D+, or observations in which a microbe was isolated) from disease-negative (D–, or microbial-negative) groups: D+ and D– data distributions overlapped. In contrast, multi-dimensional analysis of indicators designed to possess desirable features, such as a single line of observations, displayed a continuous, circular data structure, whose abrupt inflections facilitated partitioning into subsets statistically significantly different from one another. In all studies, the 3D, SB/EB approach distinguished three (steady, positive, and negative) feedback phases, in which D– data characterized the steady state phase, and D+ data were found in the positive and negative phases. In humans, spatial patterns revealed false-negative observations and three malaria-positive data classes. In both humans and bovines, methicillin-resistant Staphylococcus aureus (MRSA) infections were discriminated from non-MRSA infections.

Conclusions

More information can be extracted, from the same data, provided that data are structured, their 3D relationships are considered, and well-conserved (feedback-like) functions are estimated. Patterns emerging from such structures may distinguish well-conserved from recently developed host-microbial interactions. Applications include diagnosis, error detection, and modeling.

Reduced systemic bicyclo-prostaglandin-E2 and cyclooxygenase-2 gene expression are associated with inefficient erythropoiesis and enhanced uptake of monocytic hemozoin in children with severe malarial anemia

In holoendemic Plasmodium falciparum transmission areas, severe malaria primarily occurs in children aged <48 months and manifests as severe malarial anemia [SMA; hemoglobin (Hb) < 6.0 g/dL]. Induction of high levels of prostaglandin-E(2) (PGE(2)) through inducible cyclooxygenase-2 (COX-2) is an important host-defense mechanism against invading pathogens. We have previously shown that COX-2-derived PGE(2) levels are reduced in children residing in hyperendemic transmission regions with cerebral malaria and in those with mixed sequelae of anemia and hyperparasitemia. Our in vitro studies further demonstrated that reduced PGE(2) was due to downregulation of COX-2 gene products following phagocytosis of malarial pigment (hemozoin, PfHz). However, as COX-2-PGE(2) pathways and the impact of naturally acquired PfHz on erythropoietic responses have not been determined in children with SMA, plasma and urinary bicyclo-PGE(2)/creatinine and leukocytic COX-2 transcripts were determined in parasitized children (<36 months) stratified into SMA (n = 36) and non-SMA (Hb ≥ 6.0 g/dL; n = 38). Children with SMA had significantly reduced plasma (P = 0.001) and urinary (P < 0.001) bicyclo-PGE(2)/creatinine and COX-2 transcripts (P = 0.007). There was a significant positive association between Hb and both plasma (r = 0.363, P = 0.002) and urinary (r = 0.500, P = 0.001)] bicyclo-PGE(2)/creatinine. Furthermore, decreased systemic bicyclo-PGE(2)/creatinine was associated with inefficient erythropoiesis (i.e., reticulocyte production index; RPI < 2.0, P = 0.026). Additional analyses demonstrated that plasma (P = 0.031) and urinary (P = 0.070) bicyclo-PGE(2)/creatinine and COX-2 transcripts (P = 0.026) progressively declined with increasing concentrations of naturally acquired PfHz by monocytes. Results presented here support a model in which reduced COX-2-derived PGE(2), driven in part by naturally acquired PfHz by monocytes, promotes decreased erythropoietic responses in children with SMA.

Relationship between inflammatory mediator patterns and anemia in HIV-1 positive and exposed children with Plasmodium falciparum malaria

Anemia is the primary hematological manifestation of both Plasmodium falciparum malaria and HIV-1 in pediatric populations in sub-Saharan Africa. We have previously shown that HIV-1 positive and exposed children have greater risk of developing severe anemia (hemoglobin, Hb <6.0 g dL⁻¹) during acute malaria. However, enhanced severity of anemia was unrelated to either erythropoietic suppression or parasite-driven red blood cell hemolysis. To further explore mechanisms of anemia, circulating inflammatory mediators (IMs) were determined using a 25-plex bead array in P. falciparum-infected (Pf[+]) children (3-36 month, n = 194) stratified into three groups: HIV-1 negative (HIV-1[-]/Pf[+]); HIV-1 exposed (HIV-1[exp]/Pf[+]); and HIV-1 infected (HIV-1[+]/Pf[+]). IL-12, MIG/CXCL9, eotaxin/CCL11, and GM-CSF differed significantly and progressively increased across the groups (HIV-1[-]→HIV-1[exp]→HIV-1[+]). To further explore the relationship between the inflammatory milieu (i.e., cytokines, chemokines, and growth factors) and HIV-1 status, the large panel of IMs was reduced into discrete groups by principal component factor analysis. Of the six principal components that emerged, three components were significantly higher in the HIV-1 [+]/pf[+] and HIV[exp]/Pf[+] groups, demonstrating that inflammatory profiles differ according to HIV-1 status. Additional analyses exploring the relationship between the components and anemia revealed significant positive correlations between Hb and Component 3 (IL-1Ra, IL-7, IL-17, IFN-α, IFN-γ, MIG/CXCL9) in the HIV-1[-]/Pf[+] group, and Component 4 (IL-4, IL-5, IL-12, Eotaxin/CCL11) in HIV-1[+]/Pf[+] children. Further analyses of the HIV-1[+]/Pf[+] group revealed that IL-12 had the strongest association with anemia. Results presented here demonstrate that there are unique relationships between the inflammatory environment and anemia in HIV-1 positive and exposed children with malaria.

Meta-analysis of the association between ecstasy use and risky sexual behavior

A random-effects meta-analysis was conducted to examine the association between ecstasy use and risky sexual behavior. Analysis of 17 studies revealed a small to moderate sized effect (mean weighted r=0.211, 95% CI: 0.085-0.336). Random-effects homogeneity testing was non-significant, thus formal moderator analyses were not performed. Moreover, numerical and visual diagnostics suggested that publication bias was not a concern. It is hoped that the present meta-analytic findings and recommendations will encourage investigators to broaden their research methodologies and will stimulate new insights into the association between ecstasy use and risky sexual behavior.

Testing the significance of a correlation with nonnormal data: comparison of Pearson, Spearman, transformation, and resampling approaches

It is well known that when data are nonnormally distributed, a test of the significance of Pearson's r may inflate Type I error rates and reduce power. Statistics textbooks and the simulation literature provide several alternatives to Pearson's correlation. However, the relative performance of these alternatives has been unclear. Two simulation studies were conducted to compare 12 methods, including Pearson, Spearman's rank-order, transformation, and resampling approaches. With most sample sizes (n ≥ 20), Type I and Type II error rates were minimized by transforming the data to a normal shape prior to assessing the Pearson correlation. Among transformation approaches, a general purpose rank-based inverse normal transformation (i.e., transformation to rankit scores) was most beneficial. However, when samples were both small (n ≤ 10) and extremely nonnormal, the permutation test often outperformed other alternatives, including various bootstrap tests.

Epidemic protection zones: centred on cases or based on connectivity?

When an exotic infectious disease invades a susceptible environment, protection zones are enforced. Historically, such zones have been shaped as circles of equal radius (ER), centred on the location of infected premises. Because the ER policy seems to assume that epidemic dissemination is driven by a similar number of secondary cases generated per primary case, it does not consider whether local features, such as connectivity, influence epidemic dispersal. Here we explored the efficacy of ER protection zones. By generating a geographically explicit scenario that mimicked an actual epidemic, we created protection zones of different geometry, comparing the cost-benefit estimates of ER protection zones to a set of alternatives, which considered a pre-existing connecting network (CN) - the road network. The hypothesis of similar number of cases per ER circle was not substantiated: the number of units at risk per circle differed up to four times among ER circles. Findings also showed that even a small area (of <115 km(2) ) revealed network properties. Because the CN policy required 20% less area to be protected than the ER policy, and the CN-based protection zone included a 23.8% greater density of units at risk/km(2) than the ER-based alternative, findings supported the view that protection zones are likely to be less costly and more effective if they consider connecting structures, such as road, railroad and/or river networks. The analysis of local geographical factors (contacts, vectors and connectivity) may optimize the efficacy of control measures against epidemics.

Connecting network properties of rapidly disseminating epizoonotics

BACKGROUND

To effectively control the geographical dissemination of infectious diseases, their properties need to be determined. To test that rapid microbial dispersal requires not only susceptible hosts but also a pre-existing, connecting network, we explored constructs meant to reveal the network properties associated with disease spread, which included the road structure.

METHODS

Using geo-temporal data collected from epizoonotics in which all hosts were susceptible (mammals infected by Foot-and-mouth disease virus, Uruguay, 2001; birds infected by Avian Influenza virus H5N1, Nigeria, 2006), two models were compared: 1) 'connectivity', a model that integrated bio-physical concepts (the agent's transmission cycle, road topology) into indicators designed to measure networks ('nodes' or infected sites with short- and long-range links), and 2) 'contacts', which focused on infected individuals but did not assess connectivity.

RESULTS

THE CONNECTIVITY MODEL SHOWED FIVE NETWORK PROPERTIES: 1) spatial aggregation of cases (disease clusters), 2) links among similar 'nodes' (assortativity), 3) simultaneous activation of similar nodes (synchronicity), 4) disease flows moving from highly to poorly connected nodes (directionality), and 5) a few nodes accounting for most cases (a "20:80" pattern). In both epizoonotics, 1) not all primary cases were connected but at least one primary case was connected, 2) highly connected, small areas (nodes) accounted for most cases, 3) several classes of nodes were distinguished, and 4) the contact model, which assumed all primary cases were identical, captured half the number of cases identified by the connectivity model. When assessed together, the synchronicity and directionality properties explained when and where an infectious disease spreads.

CONCLUSIONS

Geo-temporal constructs of Network Theory's nodes and links were retrospectively validated in rapidly disseminating infectious diseases. They distinguished classes of cases, nodes, and networks, generating information usable to revise theory and optimize control measures. Prospective studies that consider pre-outbreak predictors, such as connecting networks, are recommended.

Typology of emergent eating patterns in early childhood

The stability of eating patterns from infancy through childhood is largely unknown. This study identified subgroups of children based on emergent eating patterns from ages 1 to 3 years and examined differences between groups in demographic, anthropometric and temperamental variables. We conducted secondary analyses of 262 boys and 225 girls from the Colorado Adoption Project. Three eating styles (Reactivity to Food, Predictable Appetite, Distractibility at Mealtime) and five temperaments were assessed at ages 1 and 3 years. Weight and height (length) were assessed on children and mothers. Correlations examined the stability of eating patterns, cluster analysis identified subgroups of emergent eating styles, and analysis of variance identified variables differentiating the derived subgroups. Eating styles were moderately stable over time, although all increased on average. Four subgroups were identified: Diet Expanding and Preference Establishing Eaters (37%), Emerging Reactive Tendency Eaters (23%), Emerging Food-Indifferent and Non-Fussy Eaters (31%), and Emerging High-Reactive and Fussy Eaters (9%). The subgroups differed in year 1 Wt/L and Reaction to Food, and year 1-to-3 changes in Emotionality and Reaction to Food. Four emergent eating patterns were identified. How these subgroups of children differ in later weight and health trajectories warrants research.

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.

Polymorphic variability in the 3' untranslated region (UTR) of IL12B is associated with susceptibility to severe anaemia in Kenyan children with acute Plasmodium falciparum malaria

BACKGROUND

Plasmodium falciparum malaria remains a leading cause of morbidity and mortality among African children. Innate immunity provides the first line of defence against P. falciparum infections, particularly in young children that lack naturally-acquired malarial immunity, such as the population examined here. Consistent with the fact that elevated interleukin (IL)-12 is an important component of the innate immune response that provides protective immunity against malaria, we have previously shown that suppression of IL-12 in African children is associated with the development of severe malarial anaemia (SMA). Since the role of IL12B variants in conditioning susceptibility to SMA remains largely unexplored, the association between a single nucleotide polymorphism (1188A→C, rs3212227), SMA (Hb<6.0 g/dL), circulating IL-12p40/p70 levels, and longitudinal clinical outcomes in Kenyan children (n = 756) residing in a holoendemic falciparum malaria transmission area were investigated.

RESULTS

Multivariate logistic regression analysis in children with acute malaria (n = 544) demonstrated that carriers of the C allele had increased susceptibility to SMA (CC: OR, 1.674; 95% CI, 1.006-2.673; P = 0.047, and AC: OR, 1.410; 95% CI, 0.953-2.087; P = 0.086) relative to wild type (AA). Although children with SMA had lower IL-12p40/p70 levels than the non-SMA group (P = 0.037), levels did not differ significantly according to genotype. Longitudinal analyses in the entire cohort (n = 756) failed to show any significant relationships between rs3212227 genotypes and either susceptibility to SMA or all-cause mortality throughout the three year follow-up.

CONCLUSION

The rs3212227 is a marker of susceptibility to SMA in children with acute disease, but does not appear to mediate functional changes in IL-12 production or longitudinal outcomes during the acquisition of naturally-acquired malarial immunity.

Functional haplotypes of Fc gamma (Fcγ) receptor (FcγRIIA and FcγRIIIB) predict risk to repeated episodes of severe malarial anemia and mortality in Kenyan children

Development of protective immunity against Plasmodium falciparum is partially mediated through binding of malaria-specific IgG to Fc gamma (γ) receptors. Variations in human FcγRIIA-H/R-131 and FcγRIIIB-NA1/NA2 affect differential binding of IgG sub-classes. Since variability in FcγR may play an important role in severe malarial anemia (SMA) pathogenesis by mediating phagocytosis of red blood cells and triggering cytokine production, the relationship between FcγRIIA-H/R131 and FcγRIIIB-NA1/NA2 haplotypes and susceptibility to SMA (Hb < 6.0 g/dL) was investigated in Kenyan children (n = 528) with acute malaria residing in a holoendemic P. falciparum transmission region. In addition, the association between carriage of the haplotypes and repeated episodes of SMA and all-cause mortality were investigated over a 3-year follow-up period. Since variability in FcγR can alter interferon (IFN)-γ production, a mediator of innate and adaptive immune responses, functional associations between the haplotypes and IFN-γ were also explored. During acute malaria, children with SMA had elevated peripheral IFN-γ levels (P = 0.006). Although multivariate logistic regression analyses (controlling for covariates) revealed no associations between the FcγR haplotypes and susceptibility to SMA during acute infection, the FcγRIIA-131H/FcγRIIIB-NA1 haplotype was associated with decreased peripheral IFN-γ (P = 0.046). Longitudinal analyses showed that carriage of the FcγRIIA-131H/FcγRIIIB-NA1 haplotype was associated with reduced risk of SMA (RR 0.65, 95% CI 0.46-0.90; P = 0.012) and all-cause mortality (P = 0.002). In contrast, carriers of the FcγRIIA-131H/FcγRIIIB-NA2 haplotype had increased susceptibility to SMA (RR 1.47, 95% CI 1.06-2.04; P = 0.020). Results here demonstrate that variation in the FcγR gene alters susceptibility to repeated episodes of SMA and mortality, as well as functional changes in IFN-γ production.

Gender label and perceived infant emotionality: a partial replication of a classic study

In a study often referred to as "classic," Condry and Condry (1976) showed a videotaped infant to participants, telling half of them the infant was a boy and half it was a girl. Participants who thought they were viewing a boy rated the infant's reaction to a jack-in-the-box as anger; those who thought they were viewing a girl rated the reaction as fear. Participants in the present partial replication of the Condrys' study did not rate the infant differently based on the infant's gender label, although there was evidence that participants' own sex affects their perception of an infant's emotionality. Results were discussed in light of inconsistent results among other gender-labeling studies and relevant methodological, historical, and theoretical issues.

Reliability and Validity of Gain Scores Considered Graphically

The ordinary gain score, g, is defined as g = x2 – x1, where x1 is the pretest score and x2 is the posttest score. The present study extends and refines previous research on the reliability and validity of gain scores. Using particular values as stated in the tables and graphs, the pre- and posttest reliabilities, pre- and posttest validities, ratios of pretest to posttest standard deviations, and correlations between the pretest and posttest were varied systematically to examine the effects of these parameter configurations on gain scores' reliability and validity. Results plotted graphically provide insight via visual interpretation not easily inferred using only values from a table. One interesting finding was that the reliability of a gain score can be at a maximum when the validity is at a minimum. Another is that a high correlation between pre- and posttest was beneficial to the validity of the gain score but detrimental to its reliability. By identifying the situations in which gain scores can be reliable and valid, findings inform researchers when gain scores should or should not be used.

Sample Size Determination for Health Psychology Interventions with Binomially Distributed Outcomes

Health intervention outcomes are often assessed as binomially distributed variables. In designing such interventions it is important to model the pre-intervention rate of the target behavior when performing sample size calculations. Unfortunately, the majority of sample size programs model post-intervention outcomes only, which results in exaggerated sample size estimates. An exception is Yoo and Spoth’s (1993) conditional binomial method of sample size determination. This approach explicitly models pre-intervention behavior by focusing on baserate-adjusted post-intervention outcomes, and always results in smaller sample size estimates than conventional approaches. Advantages of the conditional binomial method are discussed and user-friendly software is presented.

Infant temperament and eating style predict change in standardized weight status and obesity risk at 6 years of age

OBJECTIVE

Little research has addressed the relationships among infant temperament, eating styles and obesity risk. To address this gap, we tested whether infant temperament and eating patterns at the age of 1 year are associated with a greater increase in standardized weight status, and greater obesity risk at 6 years of age.

DESIGN

A secondary, prospective analysis of the Colorado Adoption Study was conducted. The main predictor variables were infant temperament (that is, emotionality, activity, attention span-persistence, reaction to food and soothability) and eating domains (that is, reactivity to food, predictable appetite and distractability at mealtime) at the age of 1 year, along with the body mass index (BMI) of biological mothers. The outcome measures were child weight and height (length) assessed at ages 1 through 6 years, from which weight-for-length and BMI were computed along with the standardized indexes (z-scores) and percentiles. Overweight/obesity status was computed at each year as well.

PARTICIPANTS

A primarily White sample of 262 boys and 225 girls, assessed at ages 1 through 6 years, along with their mothers.

RESULTS

Among boys, greater attention span-persistence was associated with reduced standardized weight status gain (β=-0.15, P<0.05) and reduced obesity risk (odds ratio (OR)=0.46, P=0.06). Among girls, greater soothability and negative reaction to food were associated with greater standardized weight status gain (β=0.19, P<0.01; and β=0.16, P<0.05, respectively) and increased obesity risk (OR=3.72, P=0.03; and OR=2.81, P=0.08, respectively). Biological mothers' obesity status predicted obesity risk in boys (OR=3.07, P=0.01) and girls (OR=5.94, P=0.03).

CONCLUSIONS

Male infants with less attention span, and female infants with greater soothability or a more negative food reaction, showed greater increases in standardized weight and were more likely to be overweight/obese at the age of 6 years. The role of infant temperament in pediatric obesity onset warrants greater research.

Residential status moderates the association between gender and risky sexual behavior

College students' academic performance, residential status, class rank, and gender were assessed as predictors of risky sexual behavior. All predictors were examined under two different substance use contexts, that of being 'drunk or high' and 'not drunk or high'. Results indicated that gender moderated the association between residential status and risky sex, such that males living on-campus engaged in more frequent casual sex than males living off-campus. The casual sex frequency for females did not vary as a function of residential status. The importance of studying the link between college-based environmental variables and risky sexual behavior was emphasized.

Clinical predictors of severe malarial anaemia in a holoendemic Plasmodium falciparum transmission area

Severe malarial anaemia (SMA) is a common complication of Plasmodium falciparum infections, resulting in mortality rates that may exceed 30% in paediatric populations residing in holoendemic transmission areas. One strategy for reducing the morbidity and mortality associated with SMA is to identify clinical predictors that can be readily recognized by caregivers for prompt therapeutic interventions. To determine clinical predictors of SMA, Kenyan children (3-36 months, n = 671) presenting with acute illness at a rural hospital in Siaya District were recruited. Demographic, clinical, laboratory and haematological parameters were measured upon enrolment. As human immunodeficiency virus-1 and bacteraemia promote reduced haemoglobin (Hb) concentrations, children with these infections were excluded from the analyses. Children with P. falciparum mono-infections (n = 355) were stratified into three groups: uncomplicated malaria (Hb >or= 110 g/l); non-SMA (60 Collapse

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MESH Headings

• Anemia/diagnosis
• Anemia/genetics
• Anemia/parasitology
• Child, Preschool
• Endemic Diseases
• Female
• Humans
• Infant
• Kenya/epidemiology
• Malaria, Falciparum/complications
• Malaria, Falciparum/epidemiology
• Malaria, Falciparum/genetics
• Malaria, Falciparum/transmission
• Male
• Pallor/parasitology
• Physical Examination/methods
• Platelet Count
• Reticulocyte Count
• Risk Factors

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Grants

• D43 TW005884 FIC NIH HHS
• R01 AI051305 NIAID NIH HHS
• R01 AI051305-09 NIAID NIH HHS
• T32 AI007538 NIAID NIH HHS

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Hematological predictors of increased severe anemia in Kenyan children coinfected with Plasmodium falciparum and HIV-1

Malaria and HIV-1 are coendemic in many developing countries, with anemia being the most common pediatric hematological manifestation of each disease. Anemia is also one of the primary causes of mortality in children monoinfected with either malaria or HIV-1. Although our previous results showed HIV-1(+) children with acute Plasmodium falciparum malaria [Pf(+)] have more profound anemia, potential causes of severe anemia in coinfected children remain unknown. As such, children with P. falciparum malaria (aged 3-36 months, n = 542) from a holoendemic malaria transmission area of western Kenya were stratified into three groups: HIV-1 negative [HIV-1(-)/Pf(+)]; HIV-1 exposed [HIV-1(exp)/Pf(+)]; and HIV-1 infected [HIV-1(+)/Pf(+)]. Comprehensive clinical, parasitological, and hematological measures were determined upon enrollment. Univariate, correlational, and hierarchical regression analyses were used to determine differences among the groups and to define predictors of worsening anemia. HIV-1(+)/Pf(+) children had significantly more malarial pigment-containing neutrophils (PCN), monocytosis, increased severe anemia (Hb < 6.0 g/dL), and nearly 10-fold greater mortality within 3 months of enrollment. Common causes of anemia in malaria-infected children, such as increased parasitemia or reduced erythropoiesis, did not account for worsening anemia in the HIV-1(+)/Pf(+) group nor did carriage of sickle cell trait or G6PD deficiency. Hierarchical multiple regression analysis revealed that more profound anemia was associated with elevated PCM, younger age, and increasing HIV-1 status ([HIV-1(-) --> HIV-1(exp) --> HIV-1(+)]. Thus, malaria/HIV-1 coinfection is characterized by more profound anemia and increased mortality, with acquisition of monocytic pigment having the most detrimental impact on Hb levels.

Naturally acquired hemozoin by monocytes promotes suppression of RANTES in children with malarial anemia through an IL-10-dependent mechanism

Regulated upon activation, normal T-cell expressed, and secreted (RANTES, CCL-5) is an important immunoregulatory mediator that is suppressed in children with malarial anemia (MA). Although pro-inflammatory (e.g., TNF-alpha, IL-1beta and IFN-gamma) and anti-inflammatory (e.g., IL-4, IL-10 and IL-13) cytokines regulate RANTES production, their effect on RANTES in children with MA has not been determined. Since intraleukocytic malarial pigment, hemozoin (Hz), causes dysregulation in chemokine and cytokine production, the impact of naturally acquired Hz (pfHz) on RANTES and RANTES-regulatory cytokines (TNF-alpha, IFN-gamma, IL-1beta, IL-4, IL-10, and IL-13) was examined. Circulating RANTES levels progressively declined with increasing levels of pigment-containing monocytes (PCM) (P=0.035). Additional experiments in cultured peripheral blood mononuclear cells (PBMC) showed that monocytic acquisition of pfHz (in vivo) was associated with suppression of RANTES under baseline (P=0.001) and stimulated conditions (P=0.072). Although high PCM levels were associated with decreased circulating IFN-gamma (P=0.003) and IL-10 (P=0.010), multivariate modeling revealed that only PCM (P=0.048, beta=-0.171) and IL-10 (P<0.0001, beta=-0.476) were independently associated with RANTES production. Subsequent in vitro experiments revealed that blockade of endogenous IL-10 significantly increased RANTES production (P=0.028) in PBMC from children with naturally acquired Hz. Results here demonstrate that monocytic acquisition of Hz suppresses RANTES production in children with MA through an IL-10-dependent mechanism.

Psychosocial Predictors of Dental Anxiety

Building on earlier research on psychosocial predictors of dental anxiety, this study examined the predictive ability of several demographic and personality variables. To accomplish this goal, a combined sample of 89 dental patients and 55 college students completed a self-report survey. Results indicated that greater age, female gender, lower income, greater satisfaction with life, greater thought suppression, and a stronger internal health locus of control predicted higher levels of dental anxiety. Possible strategies for reducing both thought suppression and exaggerated levels of internal health locus of control were discussed.