Partnerships in African crop biotech

Even in sub-Saharan Africa's most progressive nations, agbiotech partnerships are still often poorly oriented to end users, fragmented in scope and of limited impact in achieving the United Nation's Millennium Development Goals.     

Antibiotic selection pressure and macrolide resistance in nasopharyngeal Streptococcus pneumoniae: a cluster-randomized clinical trial

Background

It is widely thought that widespread antibiotic use selects for community antibiotic resistance, though this has been difficult to prove in the setting of a community-randomized clinical trial. In this study, we used a randomized clinical trial design to assess whether macrolide resistance was higher in communities treated with mass azithromycin for trachoma, compared to untreated control communities.

Methods and Findings

In a cluster-randomized trial for trachoma control in Ethiopia, 12 communities were randomized to receive mass azithromycin treatment of children aged 1–10 years at months 0, 3, 6, and 9. Twelve control communities were randomized to receive no antibiotic treatments until the conclusion of the study. Nasopharyngeal swabs were collected from randomly selected children in the treated group at baseline and month 12, and in the control group at month 12. Antibiotic susceptibility testing was performed on Streptococcus pneumoniae isolated from the swabs using Etest strips. In the treated group, the mean prevalence of azithromycin resistance among all monitored children increased from 3.6% (95% confidence interval [CI] 0.8%–8.9%) at baseline, to 46.9% (37.5%–57.5%) at month 12 (p = 0.003). In control communities, azithromycin resistance was 9.2% (95% CI 6.7%–13.3%) at month 12, significantly lower than the treated group (p<0.0001). Penicillin resistance was identified in 0.8% (95% CI 0%–4.2%) of isolates in the control group at 1 year, and in no isolates in the children-treated group at baseline or 1 year.

Conclusions

This cluster-randomized clinical trial demonstrated that compared to untreated control communities, nasopharyngeal pneumococcal resistance to macrolides was significantly higher in communities randomized to intensive azithromycin treatment. Mass azithromycin distributions were given more frequently than currently recommended by the World Health Organization''s trachoma program. Azithromycin use in this setting did not select for resistance to penicillins, which remain the drug of choice for pneumococcal infections.

Trial registration

www.ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00322972","term_id":"NCT00322972"}}NCT00322972 Please see later in the article for the Editors'' Summary     

Endogenous Gibberellin Profile During Christmas Rose (Helleborus niger L.) Flower and Fruit Development

Gibberellins (GAs) were identified and quantified during flower and fruit development in the Christmas rose (Helleborus niger L.), a native of southeastern Europe with a long international horticultural tradition. Physiologically, the plant differs from popular model species in two major respects: (1) following anthesis, the initially white or rose perianth (formed in this species by the sepals) turns green and persists until fruit ripening, and (2) the seed is shed with an immature embryo, a miniature endosperm, and a prominent perisperm as the main storage tissue. GA₁ and GA₄ were identified by full-scan mass spectra as the major bioactive GAs in sepals and fruit. LC-MS/MS system in accord with previously verified protocols also afforded analytical data on 12 precursors and metabolites of GAs. In the fruit, GA₄ peaked during rapid pericarp growth and embryo development and GA₁ peaked during the subsequent period of rapid nutrient accumulation in the seeds and continued pericarp enlargement. In the sepals, the flux through the GA biosynthetic pathway was highest prior to the light green stage when the photosynthetic system was induced. Unfertilized, depistillated, and deseeded flowers became less green than the seed-bearing controls; chlorophyll accumulation could be restored by applying GA₁, GA₄, and, less efficiently, GA₃ to the deseeded fruit. The sepals of unfertilized and depistillated flowers indeed contained very low levels of GA₄ and gradually decreasing levels of GA₁. However, the concentrations of their precursors and metabolites were less affected. These data suggest that a signal(s) from the fruit stimulates GA biosynthesis in the sepals resulting in greening. The fruit-derived GAs appear to be mainly involved in pericarp growth and seed development.     

Mitochondrial DNA damage is sensitive to exogenous H(2)O(2) but independent of cellular ROS production in prostate cancer cells

Intrinsic oxidative stress through enhanced production of reactive oxygen species (ROS) in prostate and other cancers may contribute to cancer progression due to its stimulating effect on cancer growth. In this study, we investigate differential responses to exogenous oxidative stimuli between aggressive prostate cancer and normal cell lines and explore potential mechanisms through interactions between cytotoxicity, cellular ROS production and oxidative DNA damage. The circular, multi-copy mitochondrial DNA (mtDNA) is used as a sensitive surrogate to oxidative DNA damage. We demonstrate that exogenous H(2)O(2) induces preferential cytotoxicity in aggressive prostate cancer than normal cells; a cascade production of cellular ROS, composed mainly of superoxide (O(2)(-)), is shown to be a critical determinant of H(2)O(2)-induced selective toxicity in cancer cells. In contrast, mtDNA damage and copy number depletion, as measured by a novel two-phase strategy of the supercoiling-sensitive qPCR method, are very sensitive to exogenous H(2)O(2) exposure in both cancer and normal cell lines. Moreover, we demonstrate for the first time that the sensitive mtDNA damage response to exogenous H(2)O(2) is independent of secondary cellular ROS production triggered by several ROS modulators regardless of cell phenotypes. These new findings suggest different mechanisms underpinning cytotoxicity and DNA damage induced by oxidative stress and a susceptible phenotype to oxidative injury associated with aggressive prostate cancer cells in vitro.     

Risk factors for ocular chlamydia after three mass azithromycin distributions

Background

An important component of the World Health Organization''s comprehensive trachoma elimination strategy is the provision of repeated annual mass azithromycin distributions, which are directed at reducing the burden of ocular chlamydia. Knowledge of characteristics associated with infection after mass antibiotic treatments could allow trachoma programs to focus resources to those most likely to be infected with ocular chlamydia.

Methodology/Principal Findings

We monitored 12 communities in rural Ethiopia that had received 3 annual mass azithromycin treatments as part of a cluster-randomized trial for trachoma. One year after the third treatment, a random sample of children from each village received conjunctival examination for follicular trachomatous inflammation (TF) and intense trachomatous inflammation (TI), conjunctival swabbing for chlamydial RNA and DNA, and a household survey. The primary outcome for this study was RNA evidence of ocular chlamydia, which we detected in 41 of 573 swabbed children (7.2%, 95%CI 2.7–17.8). In multivariate mixed effects logistic regression models, ocular chlamydial RNA was significantly associated with ocular discharge (OR 2.82, 95%CI 1.07–7.42), missing the most recent mass azithromycin treatment (OR 2.49, 95%CI 1.02–6.05), having a sibling with ocular chlamydia (OR 4.44, 95%CI 1.60–12.29), and above-median community population (OR 7.81, 95%CI 1.56–39.09). Ocular chlamydial infection was also independently associated with TF (OR 3.42, 95%CI 1.56–7.49) and TI (OR 5.39, 95%CI 2.43–11.98).

Conclusions/Significance

In areas with highly prevalent trachoma treated with multiple rounds of mass azithromycin, trachoma programs could consider continuing mass azithromycin treatments in households that have missed prior mass antibiotic treatments, in households with clinically active trachoma, and in larger communities.     

Reliability of measurements performed by community-drawn anthropometrists from rural Ethiopia

Background

Undernutrition is an important risk factor for childhood mortality, and remains a major problem facing many developing countries. Millennium Development Goal 1 calls for a reduction in underweight children, implemented through a variety of interventions. To adequately judge the impact of these interventions, it is important to know the reproducibility of the main indicators for undernutrition. In this study, we trained individuals from rural communities in Ethiopia in anthropometry techniques and measured intra- and inter-observer reliability.

Methods and Findings

We trained 6 individuals without prior anthropometry experience to perform weight, height, and middle upper arm circumference (MUAC) measurements. Two anthropometry teams were dispatched to 18 communities in rural Ethiopia and measurements performed on all consenting pre-school children. Anthropometry teams performed a second independent measurement on a convenience sample of children in order to assess intra-anthropometrist reliability. Both teams measured the same children in 2 villages to assess inter-anthropometrist reliability. We calculated several metrics of measurement reproducibility, including the technical error of measurement (TEM) and relative TEM. In total, anthropometry teams performed measurements on 606 pre-school children, 84 of which had repeat measurements performed by the same team, and 89 of which had measurements performed by both teams. Intra-anthropometrist TEM (and relative TEM) were 0.35 cm (0.35%) for height, 0.05 kg (0.39%) for weight, and 0.18 cm (1.27%) for MUAC. Corresponding values for inter-anthropometrist reliability were 0.67 cm (0.75%) for height, 0.09 kg (0.79%) for weight, and 0.22 kg (1.53%) for MUAC. Inter-anthropometrist measurement error was greater for smaller children than for larger children.

Conclusion

Measurements of height and weight were more reproducible than measurements of MUAC and measurements of larger children were more reliable than those for smaller children. Community-drawn anthropometrists can provide reliable measurements that could be used to assess the impact of interventions for childhood undernutrition.     

Performance of local light microscopy and the ParaScreen Pan/Pf rapid diagnostic test to detect malaria in health centers in Northwest Ethiopia

Background

Diagnostic tests are recommended for suspected malaria cases before treatment, but comparative performance of microscopy and rapid diagnostic tests (RDTs) at rural health centers has rarely been studied compared to independent expert microscopy.

Methods

Participants (N = 1997) with presumptive malaria were recruited from ten health centers with a range of transmission intensities in Amhara Regional State, Northwest Ethiopia during October to December 2007. Microscopy and ParaScreen Pan/Pf® RDT were done immediately by health center technicians. Blood slides were re-examined later at a central laboratory by independent expert microscopists.

Results

Of 1,997 febrile patients, 475 (23.8%) were positive by expert microscopists, with 57.7% P.falciparum, 24.6% P.vivax and 17.7% mixed infections. Sensitivity of health center microscopists for any malaria species was >90% in five health centers (four of which had the highest prevalence), >70% in nine centers and 44% in one site with lowest prevalence. Specificity for health center microscopy was very good (>95%) in all centers. For ParaScreen RDT, sensitivity was ≥90% in three centers, ≥70% in six and <60% in four centers. Specificity was ≥90% in all centers except one where it was 85%.

Conclusions

Health center microscopists performed well in nine of the ten health centers; while for ParaScreen RDT they performed well in only six centers. Overall the accuracy of local microscopy exceeded that of RDT for all outcomes. This study supports the introduction of RDTs only if accompanied by appropriate training, frequent supervision and quality control at all levels. Deficiencies in RDT use at some health centers must be rectified before universal replacement of good routine microscopy with RDTs. Maintenance and strengthening of good quality microscopy remains a priority at health center level.     

Identification and characterization of annexin gene family in rice

Plant annexins are Ca²⁺-dependent phospholipid-binding proteins and are encoded by multigene families. They are implicated in the regulation of plant development as well as protection from drought and other stresses. They are well characterized in Arabidopsis, however no such characterization of rice annexin gene family has been reported thus far. With the availability of the rice genome sequence information, we have identified ten members of the rice annexin gene family. At the protein level, they share 16–64% identity with predicted molecular masses ranging from 32 to 40 kDa. Phylogenetic analysis of rice annexins together with annexins from other monocots led to their classification into five different orthologous groups and share similar motif patterns in their protein sequences. Expression analysis by real-time RT-PCR revealed differential temporal and spatial regulation of these genes. The rice annexin genes are also found to be regulated in seedling stage by various abiotic stressors including salinity, drought, heat and cold. Additionally, in silico analysis of the putative upstream sequences was analyzed for the presence of stress-responsive cis-elements. These results provide a basis for further functional characterization of specific rice annexin genes at the tissue/developmental level and in response to abiotic stresses.