Molecular Manipulations of Extracellular Superoxide Dismutase: Functional Importance for Learning

Extracellular superoxide dismutase (EC-SOD) controls the availability of extracellular superoxide (O ₂ ^- ), which is important for a variety of physiological pathways, including the primary means of inactivating nitric oxide (NO). The role of EC-SOD in neurobehavioral function has been until now unexplored. In the current studies, the phenotypic expression of genotypic alterations of EC-SOD production in mice were characterized for spatial learning and memory. Dramatic impairments in spatial learning in the win-shift 8-arm radial maze were seen in both EC-SOD knockout mice and EC-SOD overexpressing mice. The EC-SOD overexpressing mice were further characterized as having significant deficits in a repeated acquisition task in the radial-arm maze, which permitted the dissociation of long and short-term learning. Long-term learning was significantly impaired by EC-SOD overexpression, whereas short-term learning was not significantly affected by EC-SOD overexpression. NO systems have been shown to be importantly involved in learning and memory. This may be important in the current studies because EC-SOD has primary control over the inactivation of NO. We found that EC-SOD overexpressing mice were resistant to the cognitive effects of L-NAME (N^G-nitro-L-arginine methyl ester hydrochloride), an NO synthase inhibitor. Decreased NO catabolism in these mice may have served to counter the effects of NOS inhibition by L-NAME. The current finding that EC-SOD levels that were either higher or lower than controls impaired learning demonstrates that the proper control of brain extracellular (O ₂ ^- ) may be more vital than merely reduction of brain extracelluar (O ₂ ^- ) in maintaining adequate learning function.     

Cystic fibrosis screening: a fetus with hyperechogenic bowel may be the index case.

BACKGROUND: The potential of hyperechogenic fetal bowel to act as a hallmark for prenatal cystic fibrosis screening in the general population is controversial. METHODS: Our goal was to evaluate the incidence of cystic fibrosis in 209 fetuses with hyperechogenic bowel diagnosed at routine ultrasonography and with no family history of cystic fibrosis. The diagnosis of cystic fibrosis was based on prenatal screening for the eight mutations most frequently observed in France (deltaF508, deltaI507, 1717-1G-->A, G542X, G551D, R553X, W1282X, N1303K) and at postnatal follow up. RESULTS: The overall incidence of cystic fibrosis was 7/209 (3.3%) which is 84 times the estimated risk of CF in the general population (112500). Of these seven cases, six were diagnosed prenatally based on DNA analysis (deltaF508/deltaF508, n=5; deltaF508/G542X, n=1). One case in which only one mutation had been recognised was diagnosed clinically after birth (deltaF508/unidentified mutation). Of the seven cases, none was diagnosed at 16-19 weeks, four at 16-24 weeks, and three after this. The incidence of heterozygous fetuses (15/209, 7%) was not significantly higher than the 5% expected in the general population. The mutations involved in these heterozygous cases were deltaF508 (n=13), G542X (n=1), and G551D (n=1). CONCLUSIONS: Screening for cystic fibrosis should be offered to families in which fetal hyperechogenic bowel is diagnosed at routine ultrasonography. This underlines the need to review genetic counselling in this situation where the fetus is the index case for a genetic disease.     

Regulation of male fertility by the bone-derived hormone osteocalcin

Traditionally, bone has been viewed as a relatively static tissue only fulfilling mechanical and scaffolding function. In the past decade however, this classical view of the bone has considerably evolved towards a more complex picture. It is now clear that the skeleton is not only a recipient for hormonal input but it is also an endocrine organ itself. Through the secretion of an osteoblast-derived molecule, osteocalcin, the skeleton regulates glucose homeostasis and male reproductive functions. When undercarboxylated, osteocalcin acts following its binding to a G-coupled receptor, Gprc6a, on pancreatic β cells to increase insulin secretion, on muscle and white adipose tissue to promote glucose homeostasis and on Leydig cells of the testis to favor testosterone biosynthesis. More recently, it was also shown that osteocalcin acts via a pancreas-bone-testis axis that regulates, independently of and in parallel to the hypothalamus–pituitary–testis axis, male reproductive functions by promoting testosterone biosynthesis. Lastly, in trying to expand the biological relevance of osteocalcin from mouse to human, it was shown that Gprc6a is a potential new susceptibility locus for primary testicular failure in humans. Altogether, these results shed new light on the importance of the endocrine role of the skeleton and also provide credence to the search for additional endocrine functions of this organ.     

Accuracy of echocardiography for assessing aortic root diameter.

The normal range for aortic root diameters employing the echocardiographic continuous recording technique was determined in 159 adult subjects without aortic valve disease or hypertension. In order to evaluate the accuracy of this noninvasive technique, the aortic root diameters as measured by ultrasound before operation in 31 patients with aortic valve disease were compared with their respective aortic annulus diameters as determined at the time of valve replacement. The 159 normal subjects consisted of 78 men and 81 women whose ages ranged from 18 to 74 pears (average 38). The normal range of aortic root diameters in this group was 17 to 33 mm (mean 23.7). A significant difference (P is smaller than 0.001) in aortic root diameters existed between men and women which could not be explained by differences in body surface area. The mean diameter among the 81 women was 22.4 plus or minus 3.3 mm(I SD) compared to the mean diameter in the 78 men of 25 plus or minus 3.5 mm. These results indicate a normal range for aortic root diameters which is significantly lower than previously reported. The aortic root diameter which was measured reoperatively by ultrasound in the 31 patients with aortic valve disease averaged 25.1 plus or minus 1.9 mm and did not differ significantly from the actual aortic annulus diameter of 25.5 plus or minus 2.6 mm measured at the time of surgery. The aortic root measurements by echo were within 2 mm of the corresponding annulus diameter in 25 of the 31 operated patients (80%).     

IL-10 Restrains IL-17 to Limit Lung Pathology Characteristics following Pulmonary Infection with Francisella tularensis Live Vaccine Strain

IL-10 production during intracellular bacterial infections is generally thought to be detrimental because of its role in suppressing protective T-helper cell 1 (Th1) responses. Francisella tularensis is a facultative intracellular bacterium that activates both Th1 and Th17 protective immune responses. Herein, we report that IL-10–deficient mice (Il10^−/−), despite having increased Th1 and Th17 responses, exhibit increased mortality after pulmonary infection with F. tularensis live vaccine strain. We demonstrate that the increased mortality observed in Il10^−/−-infected mice is due to exacerbated IL-17 production that causes increased neutrophil recruitment and associated lung pathology. Thus, although IL-17 is required for protective immunity against pulmonary infection with F. tularensis live vaccine strain, its production is tightly regulated by IL-10 to generate efficient induction of protective immunity without mediating pathology. These data suggest a critical role for IL-10 in maintaining the delicate balance between host immunity and pathology during pulmonary infection with F. tularensis live vaccine strain.Francisella tularensis, a facultative intracellular bacterium, because of its infectious nature and the severe disease caused by low doses of airborne bacteria, has been classified as a category A select bioterrorism agent.¹ Infection in humans is caused by two main subspecies, F. tularensis (type A) and Francisella holarctica (type B).² An F. tularensis live vaccine strain (LVS) has been developed from the F. tularensis B strain as an experimental vaccine, but is not licensed for use in humans.¹ F. tularensis LVS has been used as a representative attenuated model to address the immune requirements for protection against Francisella. By using this model, the importance of IL-12 in driving interferon γ (IFN-γ) and T-helper cell 1 (Th1) responses in immunity to F. tularensis LVS infection is well described.^3–5 In contrast, IL-17 is generally thought to play a role in protection against extracellular, but not intracellular, pathogens.⁶ However, we and others recently identified a protective role for IL-17 in the induction of cellular immunity to F. tularensis LVS pulmonary infection,^7–9 by driving the production of IFN-γ through IL-12 induction.⁷ IL-17 is a proinflammatory cytokine also known to induce chemokines, such as keratinocyte chemoattractant, macrophage inflammatory protein 2 (MIP-2), and granulocyte colony-stimulating factor (G-CSF), to mediate granulopoiesis, neutrophil recruitment, and inflammation.⁶ Accordingly, the absence of IL-17 during F. tularensis LVS pulmonary infection also results in decreased induction of G-CSF and MIP-2, as well as decreased accumulation of neutrophils and lung inflammation.⁷ Neutrophil depletion alone does not affect bacterial control after pulmonary infection with F. tularensis LVS,¹⁰ suggesting that the role for IL-17 in driving Th1 responses, and not neutrophil recruitment, was the primary immune mechanism mediating protection in this model.⁷ These data together suggest that both IL-17 and IFN-γ are required for generating protective immunity to pulmonary F. tularensis LVS infection.IL-10 is an anti-inflammatory cytokine best studied for its inhibitory effects on IL-12 production and down-regulation of Th1 responses.¹¹ Accordingly, IL-10–deficient mice show enhanced protection in models of intracellular bacterial infections, such as Mycobacterium tuberculosis¹² and Listeria monocytogenes.¹³ In addition, in a cutaneous model of F. tularensis LVS infection, IL-10–deficient mice exhibit increased protection, and this was reversed when IL-17 was depleted.¹⁴ In contrast to these published studies, in the current study, we report that after pulmonary infection with F. tularensis LVS, mice deficient in IL-10 (Il10^−/−) exhibit increased mortality. We clearly demonstrate that the increased mortality in the Il10^−/−-infected mice is not associated with loss of protective immunity, because bacterial burden between wild-type and Il10^−/− mice is similar, but is caused by exacerbated inflammation and increased lung pathology. We demonstrate that the exacerbated inflammation observed in Il10^−/−-infected mice is the result of unrestrained IL-17 production and IL-17–dependent recruitment of neutrophils and resulting lung pathology. These data together suggest that, although IL-17 is required for protective immunity against pulmonary infection with F. tularensis LVS,^7,9 IL-17 production is tightly regulated by anti-inflammatory cytokines, such as IL-10. Our studies highlight how inflammatory cytokines, such as IL-17, can be beneficial for host protection, but when produced unrestrained, can mediate host pathology.     

Copper,zinc superoxide dismutase is primarily a cytosolic protein in human cells.

The intracellular localization of human copper,zinc superoxide dismutase (Cu,Zn-SOD; superoxide:superoxide oxidoreductase, EC 1.15.1.1) was evaluated by using EM immunocytochemistry and both isolated human cell lines and human tissues. Eight monoclonal antibodies raised against either native or recombinant human Cu,Zn-SOD and two polyclonal antibodies raised against either native or recombinant human Cu,Zn-SOD were used. Fixation with 2% paraformaldehyde/0.2% glutaraldehyde was found necessary to preserve normal distribution of the protein. Monoclonal antibodies were less effective than polyclonal antibodies in recognizing the antigen after adequate fixation of tissue. Cu,Zn-SOD was found widely distributed in the cell cytosol and in the cell nucleus, consistent with it being a soluble cytosolic protein. Mitochondria and secretory compartments did not label for this protein. In human cells, peroxisomes showed a labeling density slightly less than that of cytoplasm.     

Evidence for clonal propagation in natural isolates of Plasmodium falciparum from Venezuela

We have analyzed 75 isolates of Plasmodium falciparum, collected in Venezuela during both the dry (November) and rainy (May-July) seasons, with a range of genetic markers including antigen genes and 14 random amplified polymorphic DNA (RAPD) primers. Thirteen P. falciparum stocks from Kenya and four other Plasmodium species are included in the analysis for comparison. Cross-hybridization shows that the 14 RAPD primers reveal 14 separate regions of the parasite's genome. The P. falciparum isolates are a monophyletic clade, significantly different from the other Plasmodium species. We identify three RAPD characters that could be useful as "tags" for rapid species identification. The Venezuelan genotypes fall into two discrete genetic subdivisions associated with either the dry or the rainy season; the isolates collected in the rainy season exhibit greater genetic diversity. There is significant linkage disequilibrium in each seasonal subsample and in the full sample. In contrast, no linkage disequilibrium is detected in the African sample. These results support the hypothesis that the population structure of P. falciparum in Venezuela, but not in Africa, is predominantly clonal. However, the impact of genetic recombination on Venezuelan P. falciparum seems higher than in parasitic species with long-term clonal evolution like Trypanosoma cruzi, the agent of Chagas' disease. The genetic structure of the Venezuelan samples is similar to that of Escherichia coli, a bacterium that propagates clonally, with occasional genetic recombination.     

Significant linkage disequilibrium and high genetic diversity in a population of Plasmodium falciparum from an area (Republic of the Congo) highly endemic for malaria

A study based on 28 microsatellite loci was performed on 32 isolates of Plasmodium falciparum from Pointe Noire (Republic of the Congo) and compared with a cosmopolitan sample of 21 isolates collected from different countries in Africa, Latin America, and Asia. The Pointe Noire population exhibited very high genetic diversity (A = 7.8 +/- 2.6, He = 0.79 +/- 0.11). Significant linkage disequilibria were observed in 28 of 378 pairs of microsatellite loci. This result could be explained by two non-exclusive hypotheses: 1) uniparental propagation (i.e., selfing), leading to non-panmictic associations, and/or 2) a Wahlund effect (i.e., spatial population genetic heterogeneity). These observations are in agreement with data previously obtained from isozyme loci of the same isolates, but contrast with other population genetic analyses conducted in other hyperendemic zones.     

An individual scoring system for the prediction of postpartum anaemia

Background

Postpartum anaemia (PPA) is a common postpartum complication. The goal of this study was to prospectively construct a predictive score for individual risk of PPA.

Patients et method

We prospectively analyzed factors associated with PPA (< 10 g dL⁻¹ at 48 hours postpartum). Parameters analyzed were demographic data, pregnancy characteristics, delivery and postpartum characteristics. Univariate analysis was performed using Anova or X²; the Cox model was used for multivariate analysis. The scoring system was validated using ROC curve.

Results

Analysis was performed in 475 patients and validation was carried using an additional 95 patients. Multivariate analysis found four factors independently associated with PPA: anaemia during the third trimester of the pregnancy, Southeast Asian ethnic origin, episiotomy and severe postpartum haemorrhage (PPH) identified by the use of sulprostone. According to the score derived from the Cox model, patients were classified as low (22%, score = 0), medium (55%, score = 2 or 3) and high (86%, score > 3) probability of PPA. Using the AUC of the ROC curve for both the first and the validation cohorts (performed on 95 further patients), we recorded AUCs of 72% and 70% respectively.

Conclusions

This study allowed the derivation and validation of a predictive score of PPA. This score might be useful in targeting prophylactic strategies for PPA. Such strategies could include a more active treatment of iron deficiency (increasing oral iron treatment observance or intravenous iron therapy) especially in exposed population, improvement in the prevention and treatment of postpartum haemorrhage and decreasing the use of episiotomy. Future studies must focus on the external validation and generalisation of this scoring system.