Uptake, transport, accumulation and retranslocation of potassium in grapevine rootstocks (Vitis)

The concentration and content of potassium (K) within grapevine can be regulated by selective use of rootstocks. However, the mechanisms by which rootstocks differ in the accumulation of K in the shoot of grapevine are not well understood. Therefore, the current study addresses these issues. Ungrafted rootstocks 140 Ruggeri (140 R) and 101-14 Millardet de Grasset (101-14) were exposed to K tracer rubidium (Rb) in a glasshouse, for 4 hours through roots to study uptake and transport of Rb from roots to shoot, and for 24 hours through leaf to study downward transport of Rb, in each case assessed up to 48 hours following exposure to Rb. Transpiration rates and root traits were also measured. Results showed similar total Rb uptake and similar downward transport of Rb between the two rootstocks but lower accumulation of Rb in the shoot and lower shoot/roots Rb concentration (as a result of higher retention of Rb in roots), in 140 R than that in 101-14. Transpiration rates and total root length (but not total root surface area) remained similar between two rootstocks. The study shows that short term differences in the accumulation of K in roots and shoot between rootstocks are due to differences in the transport of K from roots to the shoot, rather than by differences in net uptake or retranslocation of K. In addition, such differences were not affected by transpiration rates. The results highlight that accumulation of K in shoot of grapevine rootstocks is regulated mainly by roots

Uptake, transport, accumulation and retranslocation of potassium in grapevine rootstocks (Vitis)

The concentration and content of potassium (K) within grapevine can be regulated by selective use of rootstocks. However, the mechanisms by which rootstocks differ in the accumulation of K in the shoot of grapevine are not well understood. Therefore, the current study addresses these issues. Ungrafted rootstocks 140 Ruggeri (140 R) and 101-14 Millardet de Grasset (101-14) were exposed to K tracer rubidium (Rb) in a glasshouse, for 4 hours through roots to study uptake and transport of Rb from roots to shoot, and for 24 hours through leaf to study downward transport of Rb, in each case assessed up to 48 hours following exposure to Rb. Transpiration rates and root traits were also measured. Results showed similar total Rb uptake and similar downward transport of Rb between the two rootstocks but lower accumulation of Rb in the shoot and lower shoot/roots Rb concentration (as a result of higher retention of Rb in roots), in 140 R than that in 101-14. Transpiration rates and total root length (but not total root surface area) remained similar between two rootstocks. The study shows that short term differences in the accumulation of K in roots and shoot between rootstocks are due to differences in the transport of K from roots to the shoot, rather than by differences in net uptake or retranslocation of K. In addition, such differences were not affected by transpiration rates. The results highlight that accumulation of K in shoot of grapevine rootstocks is regulated mainly by roots. Key words: Cation, nutrient, root, shoot, translocation, transpiration

Regulation of berry quality parameters in 'Shiraz' grapevines through rootstocks (Vitis)

The concentration of potassium (K) and pH in juice of grapevines is influenced by rootstocks (Vitis). However, the performance of rootstocks with respect to berry quality parameters and inter-relationships among berry quality parameters are not well understood. The current study addresses these issues. Berry and leaf samples at harvest maturity were collected from mature field-grown 'Shiraz' grapevines grafted with each of the rootstocks Dogridge, Freedom, Ramsey, 1103 Paulsen and 140 Ruggeri. Concentrations of K in juice and petiole and pH in juice were each highest for Dogridge and Freedom, but lowest for 140 Ruggeri and 1103 Paulsen. High concentration of K in juice was related to high concentrations of malic acid and TSS but low tartaric acid/malic acid ratio. In this study, lower concentrations of K in juice and in turn pH in juice of 'Shiraz' grapevines were maintained through rootstocks such as 140 Ruggeri and 1103 Paulsen that also show lower concentrations of K in petiole and TSS in juice, and higher tartaric/malic acid concentration ratio in juice at maturity. Selective use of these rootstocks in turn helps to produce quality grape juice and wine.

Children with seizures and radiological diagnosis of focal cortical dysplasia: can drug-resistant epilepsy be predicted earlier?

Objective: Focal cortical dysplasia (FCD) is a malformation of cortical development and is associated with drug-resistant epilepsy. Standard indication for epilepsy surgery is drug resistance (as defined by the ILAE). Given the high incidence of drug resistance in these children, this delay may not be warranted. The aim of the study was to determine the proportion of patients with a presumed FCD who develop drug resistance, and evaluate post-operative outcomes. Methods: This study incorporated a survey within a regional paediatric epilepsy network and a retrospective database review of a paediatric epilepsy center serving the network to identify children with epilepsy and a presumed FCD on MRI. Results: The survey revealed that 86% of the patients with epilepsy and presumed FCD on MRI within the network were referred to our centre. Of 139 pediatric patients included in the study, 131 (94.2%) had drug-resistant epilepsy. One hundred and ten (83.9%) patients were referred to epilepsy surgery, of whom 97 underwent surgery. Of 92 with one-year postoperative follow-up, 59.8% had an Engel Class 1 (seizure-free) outcome. Concordance of location between MRI and ictal EEG was strongly associated with Engel Class 1 outcome ( p <0.001), as was older age at seizure onset ( p =0.03). Time from diagnosis to surgery, number of medications, type of surgery and histology were not associated with improved outcome. Significance: Our data suggest that most children presenting with seizures and a radiological diagnosis of FCD will develop drug-resistant epilepsy and are candidates for epilepsy surgery. The main outcome predictors are the correlation between MRI and ictal EEG localization and age at onset. This suggests that patients with FCD and epilepsy may be considered for surgery before traditional criteria of drug resistance are met. This change in practice has the potential to improve quality of life and cognitive function, and reduce burden on epilepsy services

Not surgical technique, but etiology, contralateral MRI, prior surgery, and side of surgery determine seizure outcome after pediatric hemispherotomy

OBJECTIVE: We aimed to assess determinants of seizure outcome following pediatric hemispherotomy in a contemporary cohort. METHODS: We retrospectively analyzed the seizure outcomes of 457 children who underwent hemispheric surgery in five European epilepsy centers between 2000 and 2016. We identified variables related to seizure outcome through multivariable regression modeling with missing data imputation and optimal group matching, and we further investigated the role of surgical technique by Bayes factor (BF) analysis. RESULTS: One hundred seventy seven children (39%) underwent vertical and 280 children (61%) underwent lateral hemispherotomy. Three hundred forty-four children (75%) achieved seizure freedom at a mean follow-up of 5.1 years (range 1 to 17.1). We identified acquired etiology other than stroke (odds ratio [OR] 4.4, 95% confidence interval (CI) 1.1-18.0), hemimegalencephaly (OR 2.8, 95% CI 1.1-7.3), contralateral magnetic resonance imaging (MRI) findings (OR 5.5, 95% CI 2.7-11.1), prior resective surgery (OR 5.0, 95% CI 1.8-14.0), and left hemispherotomy (OR 2.3, 95% CI 1.3-3.9) as significant determinants of seizure recurrence. We found no evidence of an impact of the hemispherotomy technique on seizure outcome (the BF for a model including the hemispherotomy technique over the null model was 1.1), with comparable overall major complication rates for different approaches. SIGNIFICANCE: Knowledge about the independent determinants of seizure outcome following pediatric hemispherotomy will improve the counseling of patients and families. In contrast to previous reports, we found no statistically relevant difference in seizure-freedom rates between the vertical and horizontal hemispherotomy techniques when accounting for different clinical features between groups

Proportion of resected seizure onset zone contacts in pediatric stereo-EEG-guided resective surgery does not correlate with outcome

Objective: We aimed to determine whether the proportion of putative seizure onset zone (SOZ) contacts resected associates with seizure outcome in a cohort of children undergoing stereoelectroencephalography (SEEG)-guided resective epilepsy surgery. / Methods: Patients who underwent SEEG-guided resective surgery over a six-year period were included. The proportion of SOZ contacts resected was determined by co-registration of pre- and post-operative imaging. Outcome was classified as seizure free (SF, Engel class I) or not seizure-free (NSF, Engel class II-IV) at last clinical follow-up. / Results: Twenty-nine patients underwent resection of whom 22 had sufficient imaging data for analysis (median age at surgery of 10 years, range 5–18). Fifteen (68.2%) were SF at median follow-up of 19.5 months (range 12–46). On univariate analysis, histopathology, was the only significant factor associated with SF (p < 0.05). The percentage of defined SOZ contacts resected ranged from 25-100% and was not associated with SF (p = 0.89). In a binary logistic regression model, it was highly likely that histology was the only independent predictor of outcome. / Conclusions: The percentage of SOZ contacts resected was not associated with SF in children undergoing SEEG-guided resective epilepsy surgery. / Significance: Factors such as spatial organisation of the epileptogenic zone, neurophysiological biomarkers and the prospective identification of pathological tissue may therefore play an important role