The roles of autophagy in cerebral ischemia

Recent studies indicate the existence of autophagy in cerebral ischemia, but the functions of autophagy in this setting remain unclear. Here we discuss the role of autophagy in cerebral ischemia based on our own publication and the literature on this subject. We propose that oxidative and endoplasmic reticulum (ER) stresses n cerebral ischemia-hypoxia are potent stimuli of autophagy in neurons. We also reviewed evidence suggesting autophagosomes may have a shorter half-life in neurons and that a fraction of LC3 protein is degraded within autolysosomes, leading to a smaller detectable amount of LC3-II in the brain while there are clear indications of on-going autophagy. Finally, we suggest autophagy is an important modifier of cell death and survival, interacting with necrosis and apoptosis in determining the outcomes and final morphology of deceased neurons.     

Plant virus expression systems for transient production of recombinant allergens in Nicotiana benthamiana

In recent years, several studies have demonstrated the use of autonomously replicating plant viruses as vehicles to express a variety of therapeutic molecules of pharmaceutical interest. Plant virus vectors for expression of heterologous proteins in plants represent an attractive biotechnological tool to complement the conventional production of recombinant proteins in bacterial, fungal, or mammalian cells. Virus vectors are advantageous when high levels of gene expression are desired within a short time, although the instability of the foreign genes in the viral genome may present problems. Similar levels of foreign protein production in transgenic plants often are unattainable, in some cases because of the toxicity of the foreign protein. Now virus-based vectors are for the first time investigated as a means of producing recombinant allergens in plants. Several plant virus vectors have been developed for the expression of foreign proteins. Here, we describe the utilization of tobacco mosaic virus- and potato virus X-based vectors for the transient expression of plant allergens in Nicotiana benthamiana plants. One approach involves the inoculation of tobacco plants with infectious RNA transcribed in vitro from a cDNA copy of the recombinant viral genome. Another approach utilizes the transfection of whole plants from wounds inoculated with Agrobacterium tumefaciens containing cDNA copies of recombinant plus-sense RNA viruses.     

Genetic variability in Puccinia striiformis f. sp. tritici populations sampled on a local scale during natural epidemics

This study investigated genetic polymorphism on a local scale in Puccinia striiformis f. sp. tritici populations during natural epidemics, in four fields located in northern France and sampled in 1998 or 1999. Two hundred and forty-seven isolates were analyzed for their amplified fragment length polymorphism (AFLP) pattern through four primer combinations, and 194 of them were also tested for their virulence factors. Only one or two pathotypes were found in each field, and all isolates had virulence v17, matching the recently introduced Yr17 resistance gene. Polymorphism on a field scale was low. Although 67 loci were polymorphic, 77% of the isolates had the same AFLP pattern, all other patterns being rare or unique. Analyses of the genetic distance between AFLP patterns based on the Jaccard index allowed us to define 12 groups, but a bootstrap analysis showed that all isolates could be assigned to a single clonal lineage. This leads us to conclude that P. striiformis f. sp. tritici populations are clonal on a field scale in northern France.     

Helicobacter pylori,HIV and Gastric Hypochlorhydria in the Malawian Population

Background

HIV and Helicobacter pylori are common chronic infections in sub-Saharan Africa. Both conditions can predispose to gastric hypochlorhydria that may be a risk factor for enteric infections and reduced drug absorption. We have investigated to what extent HIV and H. pylori infections are associated with hypochlorhydria in a Malawian cohort of patients undergoing endoscopy.

Methods

104 sequential symptomatic adults referred for gastroscopy at Queen Elizabeth Central Hospital, Blantyre, Malawi, had blood taken for rapid HIV testing and fasting serum gastrin analysis. Gastric fluid was aspirated for pH testing, and gastric biopsies were taken.

Results

After 9/104 HIV-infected patients who were already established on anti-retroviral therapy were excluded, 17/95 (25.0%) were seropositive for untreated HIV, and 68/95 (71.6%) patients were H. pylori positive by histology. Hypochlorhydria (fasting gastric pH>4.0) was present in 55.8% (53/95) of patients. H. pylori infection was significantly associated with hypochlorhydria (OR 2.91, [1.02-7.75], p=0.046). While single infection with HIV was not significantly independently associated with hypochlorhydria. H. pylori and HIV co-infection was more strongly associated with hypochlorhydria (OR 6.25, [1.33-29.43], p=0.020) than either infection alone, suggesting an additive effect of co-infection. HIV infection was associated with higher serum gastrin levels (91.3pM vs. 53.1pM, p=0.040), while H. pylori infection was not (63.1pM vs. 55.1pM, p=0.610). Irrespective of H. pylori and HIV status, most patients (>90%) exhibited pangastritis. Only three patients had histological evidence of gastric atrophy, of which only one was HIV-infected.

Conclusion

H. pylori infection was associated with fasting hypochlorhydria, while HIV was not independently associated. HIV and H. pylori co-infection, however, was more strongly associated with hypochlorhydria than H. pylori infection alone. The mechanism of this apparent additive effect between HIV and H. pylori remains unclear, but appears to be related to chronic pangastritis rather than gastric atrophy, and associated with hypergastrinaemia in HIV-infected individuals.     

Treatment-seeking practices for malaria in pregnancy among rural women in Mukono district, Uganda

Understanding treatment-seeking practices for malaria in pregnancy is necessary in designing effective programmes to address the high malaria morbidity in pregnancy. This study assessed women's perceptions on malaria in pregnancy, recognition of early signs of pregnancy and of malaria, and the cultural context in which treatment seeking takes place in Mukono District. Focus group discussions (FGD) and key informant interviews were conducted among pregnant women, non-pregnant women, adolescents and men. The results showed that malaria, locally known as omusujja, was perceived as the most common cause of ill health among pregnant women. Although malaria commonly presents with fever, some pregnant women feel hot in the womb with or without signs of fever and this illness, locally known as nabuguma, may lead to progressive weakness and occasionally to miscarriage and few respondents associated it with malaria. Primigravidae, adolescents and men were not considered at risk of omusujja or nabuguma. Similarly anaemia and low birth weight were not associated with malaria; in fact paleness was described as a normal sign of pregnancy. There are cultural and social pressures on married women to get pregnant and this forces them to conceal symptoms like feeling feverishness, backache, nausea, general weakness, loss of appetite and vomiting until they are sure these are due to pregnancy. Most women, however, could not differentiate symptoms of malaria from those of early pregnancy. There is a belief that omusujja is a normal sign of pregnancy and this is coupled with a strong cultural practice of using herbs and clays as a first resort to treat pregnancy ailments including malaria. The cultural beliefs and practices regarding delivery of twin and first births, coupled with the high cost of care, prevent women from delivering and using other services at health units.     

The need for systematic reviews of reasons

There are many ethical decisions in the practice of health research and care, and in the creation of policy and guidelines. We argue that those charged with making such decisions need a new genre of review. The new genre is an application of the systematic review, which was developed over decades to inform medical decision-makers about what the totality of studies that investigate links between smoking and cancer, for example, implies about whether smoking causes cancer. We argue that there is a need for similarly inclusive and rigorous reviews of reason-based bioethics, which uses reasoning to address ethical questions. After presenting a brief history of the systematic review, we reject the only existing model for writing a systematic review of reason-based bioethics, which holds that such a review should address an ethical question. We argue that such a systematic review may mislead decision-makers when a literature is incomplete, or when there are mutually incompatible but individually reasonable answers to the ethical question. Furthermore, such a review can be written without identifying all the reasons given when the ethical questions are discussed, their alleged implications for the ethical question, and the attitudes taken to the reasons. The reviews we propose address instead the empirical question of which reasons have been given when addressing a specified ethical question, and present such detailed information on the reasons. We argue that this information is likely to improve decision-making, both directly and indirectly, and also the academic literature. We explain the limitations of our alternative model for systematic reviews.     

Identification of an ancestral resistance gene cluster involved in the coevolution process between Phaseolus vulgaris and its fungal pathogen Colletotrichum lindemuthianum.

The recent cloning of plant resistance (R) genes and the sequencing of resistance gene clusters have shed light on the molecular evolution of R genes. However, up to now, no attempt has been made to correlate this molecular evolution with the host-pathogen coevolution process at the population level. Cross-inoculations were carried out between 26 strains of the fungal pathogen Colletotrichum lindemuthianum and 48 Phaseolus vulgaris plants collected in the three centers of diversity of the host species. A high level of diversity for resistance against the pathogen was revealed. Most of the resistance specificities were overcome in sympatric situations, indicating an adaptation of the pathogen to the local host. In contrast, plants were generally resistant to allopatric strains, suggesting that R genes that were efficient against exotic strains but had been overcome locally were maintained in the plant genome. These results indicated that coevolution processes between the two protagonists led to a differentiation for resistance in the three centers of diversity of the host. To improve our understanding of the molecular evolution of these different specificities, a recombinant inbred (RI) population derived from two representative genotypes of the Andean (JaloEEP558) and Mesoamerican (BAT93) gene pools was used to map anthracnose specificities. A gene cluster comprising both Andean (Co-y; Co-z) and Mesoamerican (Co-9) host resistance specificities was identified, suggesting that this locus existed prior to the separation of the two major gene pools of P. vulgaris. Molecular analysis revealed a high level of complexity at this locus. It harbors 11 restriction fragment length polymorphisms when R gene analog (RGA) clones are used. The relationship between the coevolution process and diversification of resistance specificities at resistance gene clusters is discussed.