Cutting edge: a new tool to evaluate human pre-erythrocytic malaria vaccines: rodent parasites bearing a hybrid Plasmodium falciparum circumsporozoite protein

Malaria vaccines containing the Plasmodium falciparum Circumsporozoite protein repeat domain are undergoing human trials. There is no simple method to evaluate the effect of vaccine-induced responses on P. falciparum sporozoite infectivity. Unlike the rodent malaria Plasmodium berghei, P. falciparum sporozoites do not infect common laboratory animals and only develop in vitro in human hepatocyte cultures. We generated a recombinant P. berghei parasite bearing P. falciparum Circumsporozoite protein repeats. These hybrid sporozoites are fully infective in vivo and in vitro. Monoclonal and polyclonal Abs to P. falciparum repeats neutralize hybrid parasite infectivity, and mice immunized with a P. falciparum vaccine are protected against challenge with hybrid sporozoites.     

Metapopulation structure favors plasticity over local adaptation

We describe a model for the evolutionary consequences of plasticity in an environmentally heterogeneous metapopulation in which specialists for each of two alternative environments and one plastic type are initially present. The model is similar to that proposed by Moran (1992) but extends her work to two sites. We show that with migration between sites the plastic type is favored over local specialists across a broad range of parameter space. The plastic type may dominate or be fixed even in an environmentally uniform site, and even if the plasticity has imperfect accuracy or bears some cost such that a local specialist has higher fitness in that site, as long as there is some migration between sites with different distributions of environmental states. These results suggest that differences among taxa in dispersal and hence realized migration rates may play a heretofore unrecognized role in their patterns of adaptive population differentiation. Migration relaxes the thresholds for both environmental heterogeneity and accuracy of plastic response above which plasticity is favored. Furthermore, small changes in response accuracy can dramatically and abruptly alter the evolutionary outcome in the metapopulation. A fitness cost to plasticity will substantially reduce the range of conditions in which the plastic type will prevail only if the cost is both large and global rather than environment specific.     

Detection of sequences in the cerebellar cortex: numerical estimate of the possible number of tidal-wave inducing sequences represented

The two major cortices of the brain--the cerebral and cerebellar cortex--are massively connected through intercalated nuclei (pontine, cerebellar and thalamic nuclei). We suggest that the two cortices co-operate by generating precise temporal patterns in the cerebral cortex that are detected in the cerebellar cortex as temporal patterns assembled spatially in the mossy fibers. We will begin by showing that the tidal-wave mechanism works in the cerebellar cortex as a read-out mechanism for such spatio-temporal patterns due to the synchronous activity they generate in the parallel fiber system which drives the Purkinje cells--the output neurons of the cerebellar cortex--to fire action potentials. We will review the anatomy of the mossy fibers and show that within a "beam", or "row" of cerebellar cortex the mossy fibers in principle could embed a vast number of tidal-wave generating sequences. Based on anatomical data we will argue that the cerebellar mossy fiber-granule cell-Purkinje cell system can potentially detect and--through learning--select from an enormous number of spatio-temporal patterns.     

Carpal bone maturation assessment by image analysis from computed tomography scans

Bone maturation is the only reliable indicator of growth and its radiologic assessment with or without automated systems is a qualitative method. Image processing allows the study of bone maturation with quantitative data. Carpal bone maturation was studied in 20 children (13 boys and 7 girls, ages ranging from 4 to 15 years) without any clinical evidence of endocrine disease by image analysis from computed tomography (CT) scans. Each wrist CT scan was processed in order to extract the carpal bones and to measure quantitative data regarding volume, axes of inertia and density for each bone. The volumes and the length of the inertia axes were significantly correlated with age. Whatever the age, there were strong correlations between the volume or the length of the main inertia axis of one carpal bone and that of all others. The decrease in the carpal bone volume measured from the processing procedure compared with the theoretical volume of bone defined from the length of the three inertia axes indicated a change in bone shape during growth. Although the mean density was constant, there was an increase in the standard deviation of density with age. Skeletal maturity assessment with image analysis from CT scans seems to be a good complementary investigation to determine bone age in children.     

MPTP Decreases MT-I mRNA In Mouse Striatum

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a drug that induces parkinsonism in humans and non-human primates. Free radicals are thought to be involved in its mechanism of action. Recently, metallothionein has been proposed to play a role as a scavenger of free radicals. In the present work, we studied the effect of MPTP neurotoxicity on brain metallothionein-I (MT-I) mRNA expression. Male C-57 black mice were treated with MPTP (30 mg/kg, i.p., daily) for 3 or 5 days. All animals were killed by cervical dislocation 7 days after the last MPTP dose. The brains were removed quickly and immediately frozen, and quantitative in situ hybridization was performed using MT-I cDNA probe. MT-I mRNA content in striatum, a region which is known to be highly predisposed and sensitive to MPTP-induced oxidative stress, decreased by 30% (3 days) and 39% (5 days) respectively, after the last MPTP administration. These results suggest that MT-I gene expression is decreased in MPTP neurotoxicity. It is suggested that the reduction of MT, an anti-oxidant and a free radical scavenger, in the striatum by MPTP enables the neurotoxin to exert maximal oxidative damage to the striatum.     

Synergistic effect of cefepime on the phagocytic killing of Staphylococcus aureus by human polymorphonuclear leucocytes and the determination of this effect by means of nitrite production

In this study the effect of cefepime on the phagocytosis and intracellular killing of Staphylococcus aureus by human polymorphonuclear leucocytes (PMNL) was determined. The opsonophagocytic killing of S. aureus was synergistically enhanced by cefepime at concentrations below 0.5 times the minimal inhibitory concentration (MIC), and four times the MIC at higher concentrations. The effect of cefepime on phagocytosis and the bactericidal activity of PMNL was also investigated by the measurement of nitrite levels using a Sievers analyser. According to the nitrite levels, cefepime enhanced not only the phagocytosis by PMNL 2.1-fold in the 0.5 MIC and 2.8-fold in the four MIC values but also the bactericidal activity of neutrophils 2.5-fold in the 0.5 MIC and 2.8-fold in the four MIC values, respectively. The beneficial cefepime-leucocyte interaction may explain the efficacy of cefepime against intracellular pathogens.     

Hybridization properties of long nucleic acid probes for detection of variable target sequences,and development of a hybridization prediction algorithm

One of the main problems in nucleic acid-based techniques for detection of infectious agents, such as influenza viruses, is that of nucleic acid sequence variation. DNA probes, 70-nt long, some including the nucleotide analog deoxyribose-Inosine (dInosine), were analyzed for hybridization tolerance to different amounts and distributions of mismatching bases, e.g. synonymous mutations, in target DNA. Microsphere-linked 70-mer probes were hybridized in 3M TMAC buffer to biotinylated single-stranded (ss) DNA for subsequent analysis in a Luminex® system. When mismatches interrupted contiguous matching stretches of 6 nt or longer, it had a strong impact on hybridization. Contiguous matching stretches are more important than the same number of matching nucleotides separated by mismatches into several regions. dInosine, but not 5-nitroindole, substitutions at mismatching positions stabilized hybridization remarkably well, comparable to N (4-fold) wobbles in the same positions. In contrast to shorter probes, 70-nt probes with judiciously placed dInosine substitutions and/or wobble positions were remarkably mismatch tolerant, with preserved specificity. An algorithm, NucZip, was constructed to model the nucleation and zipping phases of hybridization, integrating both local and distant binding contributions. It predicted hybridization more exactly than previous algorithms, and has the potential to guide the design of variation-tolerant yet specific probes.     

Clinical,Biological and Genetic Analysis of Prepubertal Isolated Ovarian Cyst in 11 Girls

Background

The cause of isolated gonadotropin-independent precocious puberty (PP) with an ovarian cyst is unknown in the majority of cases. Here, we describe 11 new cases of peripheral PP and, based on phenotypes observed in mouse models, we tested the hypothesis that mutations in the GNAS1, NR5A1, LHCGR, FSHR, NR5A1, StAR, DMRT4 and NOBOX may be associated with this phenotype.

Methodology/Principal Findings

11 girls with gonadotropin-independent PP were included in this study. Three girls were seen for a history of prenatal ovarian cyst, 6 girls for breast development, and 2 girls for vaginal bleeding. With one exception, all girls were seen before 8 years of age. In 8 cases, an ovarian cyst was detected, and in one case, suspected. One other case has polycystic ovaries, and the remaining case was referred for vaginal bleeding. Four patients had a familial history of ovarian anomalies and/or infertility. Mutations in the coding sequences of the candidate genes GNAS1, NR5A1, LHCGR, FSHR, NR5A1, StAR, DMRT4 and NOBOX were not observed.

Conclusions/Significance

Ovarian PP shows markedly different clinical features from central PP. Our data suggest that mutations in the GNAS1, NR5A1, LHCGR, FSHR StAR, DMRT4 and NOBOX genes are not responsible for ovarian PP. Further research, including the identification of familial cases, is needed to understand the etiology of ovarian PP.     

Serum IGF-1, IGFBP-3 and growth hormone levels in children with congenital heart disease: relationship with nutritional status, cyanosis and left ventricular functions

In this study we aimed to evaluate serum insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3) and growth hormone (GH) levels in children with congenital heart disease (CHD) and to determine if these parameters have any relationship to the cyanosis, nutritional status and the left ventricular systolic function. This study is prospective-randomized study which conducted in 94 CHD patients (36 girls and 58 boys, aged between one 1-192 months, 19 cyanotic CHD and 75 acyanotic CHD) and age-sex matched 54 children (26 girls and 28 boys) with no CHD. In the study group, 37 out of the 94 CHD patients (39.4%) and 16 out of the 54 controls (29.6%) had malnutrition. The difference between the cyanotic and acyanotic patients in respect to malnutrition was significant (57.9% and 34.6%, p<0.05). Serum IGF-1 levels were lower (41.8+/-3.9 microg/L, 106.9+/-17.9 microg/L respectively, p<0.001) and GH levels were higher (6.43+/-0.9 ng/ml, 3.87+/-0.5 respectively, p<0.05) in CHD patient group than the controls. Serum IGF-1 levels were significantly lower in cyanotic CHD patients than the acyanotic patients (17.2+/-3.2 microg/L, 48.7.0+/-4.6 microg/L respectively, p<0.001) and serum IGF-1 levels were both lower in acyanotic and cyanotic CHD patients than the controls (p<0.001 for both). Serum IGF-1 and GH levels were similar between the well-nourished CHD patients and CHD patients with malnutrition (p>0.05). In total study group, the most effective factors on serum IGF-1 levels was presence of CHD (p<0.001), in CHD patients, the presence of cyanosis is the most effective factor on serum IGF-1 level, the presence of malnutrition is the most effective factor on serum IGFBP-3 levels (p<0.01). In the acyanotic, cyanotic, and the entire CHD patient groups, we find no correlations between the serum IGF-1, IGFBP-3 levels and left ventricular systolic function measurements. But serum GH levels were negatively correlated with diastolic left ventricular interseptum diameter, diastolic left ventricular mass and left ventricular end-diastolic volume measurements in CHD patients. In conclusion, we determined that the most important factor on serum IGF-1 levels is cyanosis. Reduced IGF1 levels and decreased left ventricular mass with an elevated GH levels in CHD patients and these findings are prominent in the cases with cyanosis and malnutrition. For this reason we believe that chronic hypoxia plays a significant role in the pathogenesis of malnutrition and also we believe that IGF-1 deficiency seen in CHD patients may be responsible in the etiology of the decrease in left ventricular mass independently from GH.