Effect of temperature, wetness duration, and planting density on olive anthracnose caused by Colletotrichum spp

The influence of temperature, wetness duration, and planting density on infection of olive fruit by Colletotrichum acutatum and C. simmondsii was examined in laboratory and field experiments. Detached olive fruit of 'Arbequina', 'Hojiblanca', and 'Picual' were inoculated with conidia of several isolates of the pathogen and kept at constant temperatures of 5 to 35°C in humid chambers. Similarly, potted plants and stem cuttings with fruit were inoculated and subjected to wetness periods of 0 to 48 h. Infection occurred at 10 to 25°C, and disease severity was greater and the mean latent period was shorter at 17 to 20°C. Overall, C. acutatum was more virulent than C. simmondsii at temperatures <25°C. When temperature was not a limiting factor, disease severity increased with the wetness period from 0 to 48 h. Disease severity was modeled as a function of temperature and wetness duration; two critical fruit incidence thresholds were defined as 5 and 20%, with wetness durations of 1.0 and 12.2 h at the optimum temperature. In the field, anthracnose epidemics progressed faster in a super-high-density planting (1,904 olive trees/ha) than in the high-density plantings (204 to 816 olive trees/ha) and caused severe epidemics in the super-high-density planting even with the moderately resistant Arbequina. Data in this study will be useful for the development of a forecasting system for olive anthracnose epidemics.

Cestode parasitism in invasive and native brine shrimps (Artemia spp.) as a possible factor promoting the rapid invasion of A. franciscana in the Mediterranean region

Artemia franciscana is an invasive crustacean expanding its range in hypersaline wetlands in the Mediterranean region and replacing native Artemia parthenogenetica and Artemia salina. Native brine shrimps are known as intermediate hosts of cestodes; infected individuals exhibit changes in their behaviour and appearance, thus facilitating the parasite transmission to the avian hosts by predation. To assess whether invasive brine shrimps participate in the cestode life cycles to the same extent as the native species, we examined the natural infections in seven populations of Artemia spp. along the southern coast of Spain and Portugal: three populations of each A. franciscana and A. parthenogenetica and one population of A. salina. Ten cestode species were found in A. parthenogenetica, while only six were recorded in each of A. salina and A. franciscana. The overall infection was consistently higher in native than in invasive populations. For a particular cestode species, the prevalence or abundance was significantly higher in a native population for 54 pairwise comparisons and only higher for an invasive population for 4 pairwise comparisons. These results suggest that cestodes may influence competitive interactions between native and invasive brine shrimps, thus partly explaining the invasive success of A. franciscana.

[Prevalence of vascular risk factors among Spanish populations aged 70 years and over, as reported in door-to-door studies on neurological diseases]

INTRODUCTION

The aim of this study was to re-analyze door-to-door studies on neurological diseases among the elderly, in which vascular risk factors (VRF) were studied, describing methodological characteristics and prevalence of VRF.

METHODS

The surveys were identified in two phases. They were aimed at ascertaining prevalence of stroke, dementias or Parkinsonisms and, at the time of individual screening, had collected data on at least three of the following VRF: arterial hypertension (AHT), smoking habit, diabetes mellitus and hypercholesterolemia. A questionnaire was drawn up to collect the data reported in each study, and a database was constructed. VRF prevalences were quantified and analyzed using logistic regression.

RESULTS

The total of the re-analyzed population was 12,510 persons aged 70 years and over, residents in seven geographic areas during the period 1994-2002. Information available on VRF was essentially self-reported. The prevalence of self-reported AHT was 25.7 % in men and 44.2 % in women, and that of measured AHT was 61 % and 71.9 %, respectively. Populations with arterial pressure obtained by direct measurement registered 138 higher risks (OR: 1.74; 95 % CI: 1.51-2.01, and OR: 1.48; 95% CI: 1.33-1.64). Reported prevalence of diabetes, hypercholesterolemia and smoking habit were 14.3 %, 23.3% and 8.5 %, respectively.

CONCLUSIONS

There was a high prevalence of VRF among the Spanish elderly population. However, its relationship with dementia, Parkinsonisms and cerebrovascular disease could not be studied due to the poor quality of the VRF data. The differences between measured and self-reported arterial pressure suggest the existence of undetected AHT and wide scope for prevention.

Avian cestodes affect the behaviour of their intermediate host Artemia parthenogenetica: An experimental study

The brine shrimp Artemia parthenogenetica (Crustacea, Branchiopoda) is intermediate host for several cestode species whose final hosts are waterbirds. Previous field studies have shown that brine shrimps infected with cestodes have a bright red colour and are spatially segregated in the water column. However, the ethological mechanisms explaining such field observations are unknown. Changes in appearance and behaviour induced by trophically transmitted parasites have been shown to increase the risk of predation by the final host. In this experimental study, we compared the behaviour of uninfected Artemia and those infected by avian cestodes. We found that parasitised individuals behave differently from unparasitised ones in several ways. In contrast to uninfected individuals, infected brine shrimps were photophilous and showed increased surface-swimming behaviour. These observations suggest that the modified behaviour (in addition to the bright red colour of the majority of the infected individuals) results in infected brine shrimps becoming more vulnerable to avian final hosts, which facilitates parasite transmission. We discuss our results in terms of the adaptive nature of behavioural changes and their potential implications for the hypersaline ecosystem.

Impact of laboratory cross-contamination on molecular epidemiology studies of tuberculosis

Laboratory cross-contamination by Mycobacterium tuberculosis is known to be responsible for the misdiagnosis of tuberculosis, but its impact on other contexts has not been analyzed. We present the findings of a molecular epidemiology analysis in which the recent transmission events identified by a genotyping reference center were overestimated as a result of unnoticed laboratory cross-contamination in the original diagnostic laboratories.

Red and transparent brine shrimps (Artemia parthenogenetica): a comparative study of their cestode infections

Although the red colour of brine shrimps has previously been supposed to be associated with cestode parasitism, no evidence has been provided that red and transparent brine shrimps differ in their role for cestode circulation. We compared the cestode infections in 100 red and 100 transparent Artemia parthenogenetica collected from the Odiel salt pans in Spain. Seven cestode species were recorded in red, and only four of them were recorded in transparent brine shrimps. The red brine shrimps were more infected with cysticercoids than transparent individuals (prevalence, 87 vs 21%; mean intensity, 1.56 vs 1.00; mean abundance, 1.35 vs 0.21). Three cestode species (Flamingolepis liguloides, Anomotaenia tringae and Confluaria podicipina) had significantly higher prevalence and mean abundance in red brine shrimps. These results suggest that red brine shrimps have a more important role for the circulation of avian cestodes than transparent individuals of the same population.

Cyclic AMP-dependent protein kinase and mechanical heart function in ventricular hypertrophy induced by pressure overload or secondary to myocardial infarction

The role of cyclic AMP-dependent protein kinase (PKA) and systolic function during the development of left ventricular hypertrophy (LVH) still remain uncertain. The aim of this work is to study PkA activity and mechanical heart function in two experimental heart hypertrophy models: specifically, one induced by pressure overload (Goldblatt model: two kidneys, one clamped, Gb); and another secondary to myocardial infarction (MI) generated by ligation of the left coronary artery. Hypertension in the Gb group becomes evident by the third and fourth week after surgery without any significant change in the corresponding sham group. The myocardial infarction group did not show any change in systolic pressure. Different degrees of LVH for the two experimental models were observed. Relative cardiac mass (RCM) and relative ventricular mass (RVM) increased 23 and 16%, respectively, above the sham-operated rats in MI group (P < 0.05). For the pressure overload model, the increase values were 42 and 44%, respectively (P < 0.05). Left ventricular hypertrophy was also evaluated through quantitative changes in cardiac beta-myosin heavy chain which agreed with morphometric studies in Goldblatt rats. Ventricular PKA activity did not show any significant difference with respect to the sham-operated group after induction of pressure overload. For the MI model, ventricular PKA activity changed only at day 7 post-infarction with a 289% increase above the sham-operated group (P < 0.05). The absence of activation of ventricular PKA after constriction of renal artery or myocardial infarction was also corroborated by the patterns of PKA-dependent phosphorylated proteins. While force-generating capacity was increased, there was no change in ventricular PKA activity, indicating that there is no relation between this enzyme and systolic stress-strain regression lines in either pressure overload or myocardial infarction conditions. Cyclic AMP-dependent protein kinase activity had no relation with development of cardiac hypertrophy in the two experimental models of LVH. These findings contribute to the hypothesis for a multifactorial interaction of different intracellular biochemical and molecular mechanisms in the genesis of cardiac hypertrophy.