103 research outputs found
Crown dynamics in Pinus resinosa Ait. : analysis and stochastic description of branch production, branch extension growth and foliage dry weight---branch length relationships
The development of the crown structure of Pinus
resinosa Ait. was analysed in terms of three component
processes of tree growth: the number of first order
branches per whorl within the crown, the annual extension
increments of the main stem and first order branches, and
first order branch length - foliage dry weight
relationships. Factors regulating these components were
analysed and stochastic models to describe them were
developed.
Thirty-two trees from five different planted stands
located in the Quetico Section (L.ll) of the Great Lakes -
St. Lawrence Forest Region (Rowe 1972) were examined.
These stands represented various site conditions, stand
ages, and spacing categories.
The number of branches per whorl was weakly
correlated with two attributes of the parent structure:
the length of the terminal leader at the time of whorl bud
inception, and the length of the terminal leader on which
the branches occurred as whorl buds. The number of
branches per whorl was not related to the age of the tree
at the time of whorl bud inception. The binomial probability density function was a suitable model to describe the number of branches per whorl,
Extension growth of first order branches varied greatly from year to year. Differences in the extension growth of individual branches were associated with: differences in the annual height increment of the tree,
factors governing apical control, and the relative position of a branch within the crown.
There appeared to be a potential length which
one-year-old branches could attain that was dependent upon
the concurrent height increment of the tree. There also
seemed to be a potential extension increment for branches
after their first growing season that was dependent upon
initial branch length and branch age. The observed
extension increments of branches were related in a
stochastic manner to the potential for branch extension
growth to simulate naturally occurring variation.
Total branch length was a useful estimator of the
total foliage dry weight for branches of the same age
Infections in status epilepticus: A retrospective 5-year cohort study
AbstractPurposeStatus epilepticus (SE) has attracted renewed interest lately, and efforts are made to optimize every treatment stage. For refractory SE, optimal supporting care involves mechanical ventilation and intensive care unit (ICU) admission. Infections often complicate SE and recently a single-centre observational study demonstrated an association between infections and poor short-term outcome of SE in a cohort of severely ill patients. We have here attempted to replicate those findings in a different cohort.MethodWe performed a retrospective observational study and included all patients with a diagnosis of SE during 2008–2012 at a Swedish tertiary referral centre.ResultsThe cohort consisted of 103 patients (53% female, 47% male, median age 62 years, range 19–87 years). In house mortality was less than 2 and 70% of the patients’ were discharged home. The most common aetiologies of SE were uncontrolled epilepsy (37%) and brain tumours (16%). A total of 39 patients suffered infections during their stay. Presence of infection was associated with mechanical ventilation (OR 3.344, 95% CI 1.44–7.79) as well as not being discharged home (OR2.705, 95% CI 1.14–6.44), and duration of SE was significantly longer in patients with infection (median 1 day vs. 2.5 days, p<0.001).ConclusionWe conclude that the previously described association between infections, a longer SE duration, and an unfavourable outcome of SE seems valid also in SE of less severe aetiology
Ictal unilateral eye blinking and contralateral blink inhibition — A video-EEG study and review of the literature
AbstractIntroductionThere is limited information on ictal unilateral eye blinking (UEB) as a lateralizing sign in focal seizures. We identified two patients with UEB and propose a novel mechanism of UEB based on a review of the literature.Materials and methodsWe report on two patients with intractable focal epilepsy showing UEB among 269 consecutive patients undergoing noninvasive video-EEG monitoring from October 2011 to May 2013.ResultsUnilateral eye blinking was observed in 0.7% (two of 269) of our patients. Patient one had four focal seizures. Semiological signs in all of her seizures were impaired consciousness, bilateral eye blinking (BEB), and UEB on the right. During one seizure, BEB recurred after UEB with a higher blink frequency on the right. Patient two had ten focal seizures. Among them were one electrographic seizure and nine focal seizures with BEB (in 3/10) and UEB on the left (in 1/10 seizures, respectively). Both patients did not display any clonic activity of the face. In seizures with UEB, ictal EEG onset was observed over the ipsilateral frontotemporal region in both of the patients (over F8 in 2/4, Fp2-F8 in 1/4, Sp2-T2 in 1/4, and F7 in 1/1 seizures, respectively). Ictal pattern during UEB showed bilateral ictal activity (in 4/4) and ictal discharges over the ipsilateral frontal region (maximum over F3 in 1/1 seizure). Interictal EEG showed sharp waves over the same regions.DiscussionUnilateral eye blinking was ipsilateral to the frontotemporal ictal EEG pattern in both patients. The asymmetric blink frequency during BEB in patient one leads to the hypothesis that ictal UEB is caused by contralateral blink inhibition due to activation in frontotemporal cortical areas and mediated by trigeminal fibers
Midbrain–hindbrain malformations in patients with malformations of cortical development and epilepsy: A series of 220 patients
SummaryMidbrain–hindbrain malformations (MHM) may coexist with malformations of cortical development (MCD). This study represents a first attempt to investigate the spectrum of MHM in a large series of patients with MCD and epilepsy. We aimed to explore specific associations between MCD and MHM and to compare two groups of patients: MCD with MHM (wMHM) and MCD without MHM (w/oMHM) with regard to clinical and imaging features.Two hundred and twenty patients (116 women/104 men, median age 28 years, interquartile range 20–44 years at the time of assessment) with MCD and epilepsy were identified at the Departments of Neurology and Pediatrics, Innsbruck Medical University, Austria. All underwent high-resolution MRIs (1.5-T) between 01.01.2002 and 31.12.2011. Midbrain–hindbrain structures were visually assessed by three independent raters.MHM were seen in 17% (38/220) of patients. The rate of patients wMHM and w/oMHM differed significantly (p=0.004) in three categories of MCD (category I – to abnormal neuronal proliferation; category II – to abnormal neuronal migration; and category III – due to abnormal neuronal late migration/organization): MCD due to abnormal neuronal migration (31%) and organization (23%) were more commonly associated with MHM compared to those with MCD due to abnormal neuronal proliferation (9%). Extensive bilateral MCD were seen more often in patients wMHM compared to those w/oMHM (63% vs. 36%; p=0.004). In wMHM group compared to w/oMHM group there were higher rates of callosal dysgenesis (26% vs. 4%; p<0.001) and hippocampal abnormalities (52% vs. 27%; p<0.001). Patients wMHM were younger (median 25 years vs. 30 years; p=0.010) at the time of assessment and had seizure onset at an earlier age (median 5 years vs. 12 years; p=0.043) compared to those w/oMHM. Patients wMHM had higher rates of learning disability (71% vs. 38%; p<0.001), delayed developmental milestones (68% vs. 35%; p<0.001) and neurological deficits (66% vs. 47%; p=0.049) compared to those w/oMHM.The groups (wMHM and w/oMHM) did not differ in their response to antiepileptic treatment, seizure outcome, seizure types, EEG abnormalities and rate of status epilepticus. Presence of MHM in patients with MCD and epilepsy is associated with severe morphological and clinical phenotypes
Current practices in long-term video-EEG monitoring services: A survey among partners of the E-PILEPSY pilot network of reference for refractory epilepsy and epilepsy surgery.
The European Union-funded E-PILEPSY network aims to improve awareness of, and accessibility to, epilepsy surgery across Europe. In this study we assessed current clinical practices in epilepsy monitoring units (EMUs) in the participating centers.
A 60-item web-based survey was distributed to 25 centers (27 EMUs) of the E-PILEPSY network across 22 European countries. The questionnaire was designed to evaluate the characteristics of EMUs, including organizational aspects, admission, and observation of patients, procedures performed, safety issues, cost, and reimbursement.
Complete responses were received from all (100%) EMUs surveyed. Continuous observation of patients was performed in 22 (81%) EMUs during regular working hours, and in 17 EMUs (63%) outside of regular working hours. Fifteen (56%) EMUs requested a signed informed consent before admission. All EMUs performed tapering/withdrawal of antiepileptic drugs, 14 (52%) prior to admission to an EMU. Specific protocols on antiepileptic drugs (AED) tapering were available in four (15%) EMUs. Standardized Operating Procedures (SOP) for the treatment of seizure clusters and status epilepticus were available in 16 (59%). Safety measures implemented by EMUs were: alarm seizure buttons in 21 (78%), restricted patient's ambulation in 19 (70%), guard rails in 16 (59%), and specially designated bathrooms in 7 (26%). Average costs for one inpatient day in EMU ranged between 100 and 2200 Euros.
This study shows a considerable diversity in the organization and practice patterns across European epilepsy monitoring units. The collected data may contribute to the development and implementation of evidence-based recommended practices in LTM services across Europe
Life-history traits maintain the genomic integrity of sympatric species of the spruce budworm (Choristoneura fumiferana) group on an isolated forest island
Identification of widespread species collected from islands can be challenging due to the potential for local ecological and phenotypic divergence in isolated populations. We sought to determine how many species of the spruce budworm (Choristoneura fumiferana) complex reside in Cypress Hills, an isolated remnant coniferous forest in western Canada. We integrated data on behavior, ecology, morphology, mitochondrial DNA, and simple sequence repeats, comparing Cypress Hills populations to those from other regions of North America to determine which species they resembled most. We identified C. fumiferana, C. occidentalis, C. lambertiana, and hybrid forms in Cypress Hills. Adult flight phenology and pheromone attraction were identified as key life-history traits involved in maintaining the genomic integrity of species. Our study highlights the importance of extensive sampling of both specimens and a variety of characters for understanding species boundaries in biodiversity research
Diagnostic and prognostic value of noninvasive long-term video-electroencephalographic monitoring in epilepsy surgery: A systematic review and meta-analysis from the E-PILEPSY consortium
OBJECTIVE:
The European Union–funded E‐PILEPSY network (now continuing within the European Reference Network for rare and complex epilepsies [EpiCARE]) aims to harmonize and optimize presurgical diagnostic procedures by creating and implementing evidence‐based guidelines across Europe. The present study evaluates the current evidence on the diagnostic accuracy of long‐term video‐electroencephalographic monitoring (LTM) in identifying the epileptogenic zone in epilepsy surgery candidates.
METHODS:
MEDLINE, Embase, CENTRAL, and ClinicalTrials.gov were searched for relevant articles. First, we used random‐effects meta‐analytical models to calculate pooled estimates of sensitivity and specificity with respect to postsurgical seizure freedom. In a second phase, we analyzed individual patient data in an exploratory fashion, assessing diagnostic accuracy within lesional and nonlesional temporal lobe epilepsy (TLE) and extratemporal lobe epilepsy (ETLE) patients. We also evaluated seizure freedom rate in the presence of “localizing” or “nonlocalizing” LTM within each group. The quality of evidence was assessed using the QUADAS‐2 tool and the GRADE approach.
RESULTS:
Ninety‐four studies were eligible. Forty‐four were included in sensitivity meta‐analysis and 34 in specificity meta‐analysis. Pooled sensitivity was 0.70 (95% confidence interval [CI] = 0.60‐0.80) and specificity was 0.40 (95% CI = 0.27‐0.54). Subgroup analysis was based on individual data of 534 patients (41% men). In lesional TLE patients, sensitivity was 0.85 (95% CI = 0.81‐0.89) and specificity was −0.19 (95% CI = 0.13‐0.28). In lesional ETLE patients, a sensitivity of 0.47 (95% CI = 0.36‐0.58) and specificity of 0.35 (95% CI = 0.21‐0.53) were observed. In lesional TLE, if LTM was localizing and concordant with resection site, the seizure freedom rate was 247 of 333 (74%), whereas in lesional ETLE it was 34 of 56 (61%). The quality of evidence was assigned as “very low.”
SIGNIFICANCE:
Long‐term video‐electroencephalographic monitoring is associated with moderate sensitivity and low specificity in identification of the epileptogenic zone. Sensitivity is remarkably higher in lesional TLE compared to lesional ETLE. Substantial heterogeneity across the studies indicates the need for improved design and quality of reporting
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