The role of age and exposure to Plasmodium falciparum in the rate of acquisition of naturally acquired immunity: a randomized controlled trial

BACKGROUND

The rate of acquisition of naturally acquired immunity (NAI) against malaria predominantly depends on transmission intensity and age, although disentangling the effects of these is difficult. We used chemoprophylaxis to selectively control exposure to P. falciparum during different periods in infancy and explore the effect of age in the build-up of NAI, measured as risk of clinical malaria.

METHODS AND FINDINGS

A three-arm double-blind randomized placebo-controlled trial was conducted in 349 infants born to Mozambican HIV-negative women. The late exposure group (LEG) received monthly Sulfadoxine-Pyrimethamine (SP) plus Artesunate (AS) from 2.5-4.5 months of age and monthly placebo from 5.5-9.5 months; the early exposure group (EEG) received placebo from 2.5-4.5 months and SP+AS from 5.5-9.5 months; and the control group (CG) received placebo from 2.5-9.5 months. Active and passive case detection (PCD) were conducted from birth to 10.5 and 24 months respectively. The primary endpoint was time to first or only episode of malaria in the second year detected by PCD. The incidence of malaria during the second year was of 0.50, 0.51 and 0.35 episodes/PYAR in the LEG, EEG and CG respectively (p = 0.379 for the adjusted comparison of the 3 groups). The hazard ratio of the adjusted comparison between the LEG and the CG was 1.38 (0.83-2.28, p = 0.642) and that between the EEG and the CG was 1.35 (0.81-2.24, p = 0.743).

CONCLUSIONS

After considerably interfering with exposure during the first year of life, there was a trend towards a higher risk of malaria in the second year in children who had received chemoprophylaxis, but there was no significant rebound. No evidence was found that the age of first exposure to malaria affects the rate of acquisition of NAI. Thus, the timing of administration of antimalarial interventions like malaria vaccines during infancy does not appear to be a critical determinant.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00231452.

Mental health and quality of life in alcoholic liver disease patients after liver transplantation: a prospective controlled study

OBJECTIVE

Alcoholic liver disease (ALD) is one of the most important indications for liver transplantation. Discordant conclusions have been found concerning quality of life and mental health after transplantation in this particular group. The aim of this work was to investigate improvements in mental health and quality of life among transplanted patients for ALD.

METHODS

We studied 45 consecutive transplant candidates with ALD, attending the outpatient clinics. Among these patients we transplanted 24 with the control candidates remaining in wait for transplantation.

RESULTS

There was a significant improvement in all mental health and quality of life dimensions among the transplanted ALD group. We also observed a favorable evolution of coping mechanisms (CM) in this group.

CONCLUSION

There is a favorable adjustment of ALD patients after transplantation as shown in CM evolution, which might explain the improved mental health and quality-of-life dimensions.

Psychiatric and psychosocial predictors of medical outcome after liver transplantation: a prospective, single-center study

OBJECTIVE

Recognizing the potential impact of psychiatric and psychosocial factors on liver transplant patient outcomes is essential to apply special follow-up for more vulnerable patients. The aim of this article was to investigate the psychiatric and psychosocial factors predicted medical outcomes of liver transplanted patients.

METHODS

We studied 150 consecutive transplant candidates, attending our outpatient transplantation clinic, including 84 who had been grafted 11 of whom died and 3 retransplanted.

RESULTS

We observed that active coping was an important predictor of length of stay after liver transplantation. Neuroticism and social support were important predictors of mortality after liver transplantation.

CONCLUSION

It may be useful to identify patients with low scores for active coping and for social support and high scores for neuroticism to design special modes of follow-up to improve their medical outcomes.

Comparison of commercial kits to measure cytokine responses to Plasmodium falciparum by multiplex microsphere suspension array technology

Background

Multiplex cytokine profiling systems are useful tools for investigating correlates of protective immunity. Several Luminex and flow cytometry methods are commercially available but there is limited information on the relative performance of different kits. A series of comparison experiments were carried out to determine the most appropriate method for our subsequent studies.

Methods

Two Luminex methods were compared, the Bio-Rad human 17-plex panel and the Invitrogen (formerly BioSource) human cytokine 10-plex kit, and two flow cytometry methods, the Becton Dickinson Human Th1/Th2 Cytokine Kit (CBA) and the Bender MedSystems Human Th1/Th2 11plex FlowCytomix Multiplex Kit. All kits were tested for the measurement of cytokines in supernatants collected from human leukocytes stimulated with viable Plasmodium falciparum infected red blood cells (iRBC) or P. falciparum schizont lysates.

Results

Data indicated that the kits differed in sensitivity and reproducibility depending on the cytokine, and detected different quantities of some cytokines. The Bio-Rad 17-plex kit was able to detect more positive responses than the Invitrogen 10-plex kit. However, only when detecting IL-1, IL-6 or TNF did the two Luminex based methods correlate with one another. In this study, the flow cytometry based techniques were less variable and correlated better with one another. The two flow cytometry based kits showed significant correlation when detecting IFN-γ, IL-2, TNF, IL-10 and IL-6, but overall the BD kit detected more positive responses than the Bender MedSystems kit.

Conclusions

The microsphere suspension array technologies tested differed in reproducibility and the absolute quantity of cytokine detected. Sample volume, the number of cytokines measured, and the time and cost of the assays also differed. These data provide an accurate assessment of the four techniques, which will allow individual researchers to select the tool most suited for their study population.

On the role of subtype selective adenosine receptor agonists during proliferation and osteogenic differentiation of human primary bone marrow stromal cells

Purines are important modulators of bone cell biology. ATP is metabolized into adenosine by human primary osteoblast cells (HPOC); due to very low activity of adenosine deaminase, the nucleoside is the end product of the ecto-nucleotidase cascade. We, therefore, investigated the expression and function of adenosine receptor subtypes (A(1) , A(2A) , A(2B) , and A(3) ) during proliferation and osteogenic differentiation of HPOC. Adenosine A(1) (CPA), A(2A) (CGS21680C), A(2B) (NECA), and A(3) (2-Cl-IB-MECA) receptor agonists concentration-dependently increased HPOC proliferation. Agonist-induced HPOC proliferation was prevented by their selective antagonists, DPCPX, SCH442416, PSB603, and MRS1191. CPA and NECA facilitated osteogenic differentiation measured by increases in alkaline phosphatase (ALP) activity. This contrasts with the effect of CGS21680C which delayed HPOC differentiation; 2-Cl-IB-MECA was devoid of effect. Blockade of the A(2B) receptor with PSB603 prevented osteogenic differentiation by NECA. In the presence of the A(1) antagonist, DPCPX, CPA reduced ALP activity at 21 and 28 days in culture. At the same time points, blockade of A(2A) receptors with SCH442416 transformed the inhibitory effect of CGS21680C into facilitation. Inhibition of adenosine uptake with dipyridamole caused a net increase in osteogenic differentiation. The presence of all subtypes of adenosine receptors on HPOC was confirmed by immunocytochemistry. Data show that adenosine is an important regulator of osteogenic cell differentiation through the activation of subtype-specific receptors. The most abundant A(2B) receptor seems to have a consistent role in cell differentiation, which may be balanced through the relative strengths of A(1) or A(2A) receptors determining whether osteoblasts are driven into proliferation or differentiation.

Adherence correlates in liver transplant candidates

The study sought to investigate the psychiatric and psychosocial correlates of multidimensional adherence among liver transplant candidates. A liver transplant candidate sample (N = 100), comprising consecutive patients attending outpatient clinics of a liver transplantation central unit, was assessed by means of the Multidimensional Adherence Questionnaire (MAQ; Telles-Correia 2007), the Diagnostic and Statistical Manual of Mental Disorders, Revised 4th Edition (DSM-IV-TR) criteria, the Toronto Alexithymia Scale (TAS), the NEO Five-Factor Inventory (NEO-FFI) personality inventory, the Hospital Anxiety and Depression Scale (HADS), the Brief COPE, and the Psychological Assessment of Candidates for Transplantation (PACT). We found that multidimensional adherence positively correlated with personality traits (agreeableness), good social support, and coping strategies (planning).

Cephalopod dynamic camouflage: bridging the continuum between background matching and disruptive coloration

Individual cuttlefish, octopus and squid have the versatile capability to use body patterns for background matching and disruptive coloration. We define--qualitatively and quantitatively--the chief characteristics of the three major body pattern types used for camouflage by cephalopods: uniform and mottle patterns for background matching, and disruptive patterns that primarily enhance disruptiveness but aid background matching as well. There is great variation within each of the three body pattern types, but by defining their chief characteristics we lay the groundwork to test camouflage concepts by correlating background statistics with those of the body pattern. We describe at least three ways in which background matching can be achieved in cephalopods. Disruptive patterns in cuttlefish possess all four of the basic components of 'disruptiveness', supporting Cott's hypotheses, and we provide field examples of disruptive coloration in which the body pattern contrast exceeds that of the immediate surrounds. Based upon laboratory testing as well as thousands of images of camouflaged cephalopods in the field (a sample is provided on a web archive), we note that size, contrast and edges of background objects are key visual cues that guide cephalopod camouflage patterning. Mottle and disruptive patterns are frequently mixed, suggesting that background matching and disruptive mechanisms are often used in the same pattern.

Importance of Depression and Active Coping in Liver Transplant Candidates' Quality of Life

Objective

To investigate the importance of psychiatric and psychological factors such as depression, anxiety, personality traits, and coping strategies in liver transplant candidates' quality of life.

Methods

A total of 131 consecutive liver transplant candidates attending outpatient clinics at a liver transplantation central unit were assessed by means of the Medical Outcomes Study Short Form quality-of-life questionnaire, psychiatric diagnostic criteria from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, a personality inventory (NEO Five-Factor Inventory), the Hospital Anxiety and Depression Scale, and the Brief COPE scale.

Results and Conclusions

Both physical and mental components of quality of life are far more correlated with depression and active coping strategy than with clinical and sociodemographic factors. Neuroticism was also strongly correlated with the mental component of quality of life, and employment was correlated with the physical component of quality of life.