New class I and II HLA alleles strongly associated with opposite patterns of progression to AIDS.

The genetics of resistance to infection by HIV-1 cohort consists of 200 slow and 75 rapid progressors to AIDS corresponding to the extremes of HIV disease outcome of 20,000 Caucasians of European descent. A comprehensive analysis of HLA class I and class II genes in this highly informative cohort has identified HLA alleles associated with fast or slow progression, including several not described previously. A quantitative analysis shows an overall HLA influence independent of and equal in magnitude (for the protective effect) to the effect of the CCR5-Delta32 mutation. Among HLA class I genes, A29 (p = 0.001) and B22 (p < 0.0001) are significantly associated with rapid progression, whereas B14 (p = 0.001) and C8 (p = 0.004) are significantly associated with nonprogression. The class I alleles B27, B57, C14 (protective), and C16, as well as B35 (susceptible), are also influential, but their effects are less robust. Influence of class II alleles was only observed for DR11. These results confirm the influence of the immune system on disease progression and may have implications on peptide-based vaccine development.     

Pollen-based biome reconstruction for southern Europe and Africa 18,000 yr bp

Pollen data from 18,000 ¹⁴C yr bp were compiled in order to reconstruct biome distributions at the last glacial maximum in southern Europe and Africa. Biome reconstructions were made using the objective biomization method applied to pollen counts using a complete list of dryland taxa wherever possible. Consistent and major differences from present‐day biomes are shown. Forest and xerophytic woods/scrub were replaced by steppe, both in the Mediterranean region and in southern Africa, except in south‐western Cape Province where fynbos (xerophytic scrub) persisted. Sites in the tropical highlands, characterized today by evergreen forest, were dominated by steppe and/or xerophytic vegetation (cf. today’s Ericaceous belt and Afroalpine grassland) at the last glacial maximum. Available data from the tropical lowlands are sparse but suggest that the modern tropical rain forest was largely replaced by tropical seasonal forest while the modern seasonal or dry forests were encroached on by savanna or steppe. Montane forest elements descended to lower elevations than today.     

Plasmodium falciparum: Drug sensitivity in vitro of isolates before and after adaptation to continuous culture

Fifteen strains of Plasmodium falciparum have been cultivated since 1979 using the Trager and Jensen method of continuous culture on isolates from malaria patients. One hundred and two drug sensitivity studies have been carried out on these strains using a semimicro test. Three isolates, initially resistant to chloroquine, adapted rapidly to in vitro cultivation and maintained their high level of resistance (ED₅₀ above 660 nM). Eleven isolates, initially chloroquine sensitive (ED₅₀ under 90 nM) became resistant to this drug (ED₅₀ = 190 to 1950 nM) after the 2–15 weeks required for their adaptation to continuous culture. The resistance of these strains never decreased during the following 15 months of continuous culture. The sensitivity to quinine varied initially from one strain to another (ED₅₀= 160 to 660 nM) and fluctuated during cultivation in the ratio of 1, 3.5 for a given strain. The sensitivity of mefloquine remained high for all strains (ED₅₀ under 150 nM) but one (ED₅₀ = 560 nM). These results suggest that there might be a relationship between in vitro adaptation to culture of P. falciparum by the Trager-Jensen method and a chloroquine-resistant characteristic of the strain. There is the possibility of the emergence of a drug-resistant subpopulation or of changes in the metabolic pathways.     

Viruslike particles containing knob-associated histidine-rich protein are secreted into the culture medium of Plasmodium falciparum in vitro cultures

This report describes the isolation of a viruslike particle from in vitro cultures of the human malaria parasite P. falciparum. Electronmicroscopic observations suggest that the particles are liberated into the culture medium by budding from the erythrocyte membrane. The density of the free particles is 1.16, they contain nucleic acid and two distinct molecular species of the knob-associated Histidine-rich protein. Proteins of the particles are recognized by sera from malaria patients. The previously described knobs may correspond to viral coats inserted in the membrane.     

Quantitative analysis of the antiviral activity of CD8(+) T cells from human immunodeficiency virus-positive asymptomatic patients with different rates of CD4(+) T-cell decrease

We have measured in 22 asymptomatic human immunodeficiency virus type 1-infected patients (10 rapid progressors and 12 slow progressors) the proviral load of CD4(+) T cells homogeneously superinfected by the same dose of a non-syncytium-inducing virus in the presence or in the absence of autologous CD8(+) T cells. We demonstrated that the antiviral activity of CD8(+) T cells was highly predictive of the rate of peripheral CD4(+) T-cell decline.     

Physiology of maize II: Identification of physiological markers representative of the nitrogen status of maize (Zea mays) leaves during grain filling

To illustrate the development of the source-to-sink transition in maize leaves during the grain-filling period, an integrated physiological-agronomic approach is presented in this study. The evolution of physiological markers such as total leaf nitrogen (N), chlorophyll, soluble protein, amino acid and ammonium contents was monitored from silking to a period close to maturity in different leaf stages of three maize genotypes grown at high and low levels of N fertilization. In addition, the activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH), two enzymes known to play a direct or an indirect role during leaf N remobilization, were measured. In the three genotypes examined, we found that a general decrease of most metabolic and enzyme markers occurred during leaf ageing and that this decrease was enhanced when plants were N starved. In contrast, such variations were not observed between different sections of a single leaf even at an advanced stage of leaf senescence. We found that there is a strong correlation between total N, chlorophyll, soluble protein and GS activity, which is not dependent upon the N fertilization level, which indicates the N status of the plant, either in a single leaf or during ageing. In contrast, ammonium, amino acids and GDH activity were not subject to such variations, thus suggesting that they are indicators of the metabolic activity of the whole plant in response to the level of N fertilization. The use of these markers to predict the N status of maize as a function of both plant development and N availability is discussed.     

Optimizing Human Synovial Fluid Preparation for Two-Dimensional Gel Electrophoresis

Background

Prenatal screening for Down Syndrome (DS) would benefit from an increased number of biomarkers to improve sensitivity and specificity. Improving sensitivity and specificity would decrease the need for potentially risky invasive diagnostic procedures.

Results

We have performed an in depth two-dimensional difference gel electrophoresis (2D DIGE) study to identify potential biomarkers. We have used maternal plasma samples obtained from first and second trimesters from mothers carrying DS affected fetuses compared with mothers carrying normal fetuses. Plasma samples were albumin/IgG depleted and expanded pH ranges of pH 4.5 - 5.5, pH 5.3 - 6.5 and pH 6 - 9 were used for two-dimensional gel electrophoresis (2DE). We found no differentially expressed proteins in the first trimester between the two groups. Significant up-regulation of ceruloplasmin, inter-alpha-trypsin inhibitor heavy chain H4, complement proteins C1s subcomponent, C4-A, C5, and C9 and kininogen 1 were detected in the second trimester in maternal plasma samples where a DS affected fetus was being carried. However, ceruloplasmin could not be confirmed as being consistently up-regulated in DS affected pregnancies by Western blotting.

Conclusions

Despite the in depth 2DE approach used in this study the results underline the deficiencies of gel-based proteomics for detection of plasma biomarkers. Gel-free approaches may be more productive to increase the number of plasma biomarkers for DS for non-invasive prenatal screening and diagnosis.