Longitudinal cognitive decline in mild cognitive impairment subjects with early amyloid-ß neocortical deposition.

PURPOSE: The rate of clinical progression of cognitive impairment in subjects with early amyloid deposition is unknown. The primary aim of the study was to follow the rate of cognitive decline over 1 year in patients with amnestic mild cognitive impairment (aMCI) by determining amyloid retention levels in terms of standardized uptake value ratios (SUVr) that ranged from 0.85 to 1.57. The secondary objective was to compare the rate of cognitive decline between subjects with and without early amyloid positivity. METHODS: Of 66 aMCI subjects evaluated with [18F]florbetaben PET imaging and neuropsychological tests at baseline, 41 completed the 1-year follow-up. Amyloid status was determined with SUVr cut-off values generated from baseline images by visual assessment by three independent certified readers. Repeated-measures ANOVA with amyloid load and neuropsychological scores as the main effects was use to test group, time and group-by-time interactions. The Tukey post-hoc test was used to analyse all significant interactions. RESULTS: Of the 41 aMCI subjects, 38 completed the assessment according to the study protocol. Amyloid-positive (Aß+ ) subjects (N = 18, age 75.6 ± 5.8 years, six men, 12 women) showed greater clinical deterioration according to the Mattis Dementia Rating Scale (MDRS) score (p = 0.006). Amyloid-negative (Aß-) subjects (N = 20, age 72.4 ± 5.8 years, 11 men, 6 women) showed no significant changes in MDRS score over 1 year. MDRS score significantly decreased (MDRS+) in 37% of the aMCI subjects, and remained stable (MDRS-) in the remaining 63%. Among subjects with cognitive deterioration, 86% were Aß+ and 14% were Aß-, while 25% of the MDRS- subjects were Aß+ and 75% were Aß- (χ2 = 13, P = 0.0003). SUVr above 1.21 identified individuals who would show significant progression over 1 year, with a sensitivity of 67% and a specificity of 90%, as compared to Aß- subjects. The positive predictive value, negative predictive value, and likelihood ratio were 86% (95% CI 70-94%), 75% (95% CI 58-87%), 7 (95% CI 5-10). CONCLUSION: This study demonstrated that early amyloid deposition predicts cognitive decline in subjects with aMCI, with a higher rate of decline in those with SUVr above a threshold of 1.21. Detection of early amyloid positivity may help in selecting the target population for preventive therapeutic interventions and in designing treatment trials (Trial number, EudraCT 2015-001184-39).

In vitro propagation of Opuntia ellisiana Griff and acclimatization to field conditions

The genus Opuntia is a valuable forage resource in arid and semiarid lands during periods of drought and shortage of herbaceous plants. However, absolute minimum temperatures in the plains of Mendoza represent a limiting factor to cultivate several species. Opuntia ellisiana is a cold hardy species, so the goals of this study were to massively propagate is using in vitro culture techniques, and then to acclimatize plantlets obtained to field conditions. Different sterilization protocols were tested. Areoles were isolated in laminar airflow cabinet, and cultured on Murashige-Skoog medium, supplemented with sucrose and different BAP and IBA combinations. Explants were grown at 27 +/- 2 degrees C, under a 16-h photoperiod. The shoots produced were used in the rooting assay using different auxin combinations. In the most efficient growth treatment, plantlets reached 100% shooting after 35 days of culture, and a mean length of 10.2 mm after 49 days of culture. A 100% rooted plantlets was obtained on a medium containing 5 mg L-1 IBA, after 12 days of culture. Acclimatization was achieved under greenhouse conditions, showing 100% plantlet survival. This study suggests that O. ellisiana can be successfully micropropagated by areoles, and easily acclimatizated to field conditions.

In vitro propagation of Opuntia ellisiana Griff and acclimatization to field conditions

The genus Opuntia is a valuable forage resource in arid and semiarid lands during periods of drought and shortage of herbaceous plants. However, absolute minimum temperatures in the plains of Mendoza represent a limiting factor to cultivate several species. Opuntia ellisiana is a cold hardy species, so the goals of this study were to massively propagate is using in vitro culture techniques, and then to acclimatize plantlets obtained to field conditions. Different sterilization protocols were tested. Areoles were isolated in laminar airflow cabinet, and cultured on Murashige-Skoog medium, supplemented with sucrose and different BAP and IBA combinations. Explants were grown at 27 +/- 2 degrees C, under a 16-h photoperiod. The shoots produced were used in the rooting assay using different auxin combinations. In the most efficient growth treatment, plantlets reached 100% shooting after 35 days of culture, and a mean length of 10.2 mm after 49 days of culture. A 100% rooted plantlets was obtained on a medium containing 5 mg L-1 IBA, after 12 days of culture. Acclimatization was achieved under greenhouse conditions, showing 100% plantlet survival. This study suggests that O. ellisiana can be successfully micropropagated by areoles, and easily acclimatizated to field conditions. (AU)

Effect of growth conditions on carboxylating enzymes of Zea mays plants.

Phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) and ribulose-1,5-bisphospate (RuBP) carboxylase (EC 4.1.1.39) activities in leaves of different maize hybrids grown under field conditions (high light intensity) and in a growth chamber (low light intensity) were determined. Light intensity and leaf age affected PEP carboxylase activity, whereas RuBP carboxylase was affected by leaf age only at low light intensity. PEP carboxylase/RuBP carboxylase activity ratio decreased according to light intensity and leaf age. Results demonstrate that Zea mays grown under field conditions is a typical C4 species in all leaves independently from their position on the stem, whereas it may be a C3 plant when it is grown in a growth chamber at low light intensity.