Occupying about 14 % of the world's surface, the Southern Ocean plays a fundamental role in ocean and atmosphere circulation, carbon cycling and Antarctic ice-sheet dynamics. Unfortunately, high ...interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine–atmosphere–ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on southwest Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52–54° S). Our annually resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the 1940s, a phenomenon predating the observational record. Climate reanalysis and modelling show a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer. Our results suggest that modern observed high interannual variability was established across the mid-twentieth century, and that the influence of contemporary equatorial Pacific temperatures may now be a permanent feature across the mid- to high latitudes.
BACKGROUNDBupropion is associated with a dose-dependent increased risk of seizures. Use of concomitant bupropion and electroconvulsive therapy (ECT) remains controversial because of an increased risk ...of prolonged seizures. This is the first systematic evaluation of the effect of bupropion on ECT.
METHODSA case group (n = 119), patients treated with concomitant ECT and bupropion, was compared with an age and gender frequency–matched control group (n = 261), treated with only ECT. Electroconvulsive therapy treatment data including seizure length, number of treatments, and concurrent medications were extracted. Longitudinal mixed models examined ECT versus ECT + bupropion group differences over the course of treatments measured by seizure duration (electroencephalogram EEG and motor). Multivariable models examined the total number of treatments and first and last seizure duration. All models considered group differences with ECT treatment measures adjusted for age, gender, benzodiazepine treatment, lead placement, and setting.
RESULTSElectroconvulsive therapy treatment with bupropion led to shorter motor seizure duration (0.047) and EEG seizure duration (P = 0.001). The number of ECT treatments (7.3 vs 7.0 treatments; P = 0.23), respectively, or the probability of a prolonged seizure (P = 0.15) was not significantly different. Benzodiazepine use was significantly more common in control subjects (P = 0.01).
LIMITATIONSThis is a retrospective analysis limited in part by unavailable variables (seizure threshold, nature of EEG and motor seizure monitoring, type of ECT device, dosing and formulation of bupropion, and duration of the current depressive illness).
CONCLUSIONSThis study revealed a significantly shorter duration in seizure length with ECT + concomitant bupropion, but not in the number of required treatments in those treated compared with ECT without bupropion. There remains a critical need to reevaluate the efficacy of concomitant use of psychotropic medications + ECT.
The late 16th‐century North American megadrought was notable for its persistence, extent, intensity, and occurrence after the main interval of megadrought activity during the Medieval Climate ...Anomaly. Forcing from sea surface temperatures (SSTs) in the tropical Pacific is considered a possible driver of megadroughts, and we investigate this hypothesis for the late 16th‐century event using two new 600‐year long hydroclimate field reconstructions from Mexico and Australia. Areas represented by these reconstructions have strong teleconnections to tropical Pacific SSTs, evidenced by the leading principal component in each region explaining ∼40% of local hydroclimate variability and correlating significantly with the boreal winter (December‐January‐February) NINO 3.4 index. Using these two principal components as predictors, we develop a skillful reconstruction of the December‐January‐February NINO 3.4 index. The reconstruction reveals that the late 16th‐century megadrought likely occurred during one of the most persistent and intense periods of cold tropical Pacific SST anomalies of the last 600 years (1566–1590 C.E.; median NINO 3.4 = −0.79 K). This anomalously cold period coincided with a major filling episode for Kati Thanda‐Lake Eyre in Australia, a hydroclimate response dynamically consistent with the reconstructed SST state. These results offer new evidence that tropical Pacific forcing was an important driver of the late 16th‐century North American megadrought over the Southwest and Mexico, highlighting the large amplitude of natural variability that can occur within the climate system.
Key Points
One of the most severe megadroughts in North America occurred in the late 16th‐century
We show this event occurred during a 25‐year cold period in the tropical Pacific Ocean
This provides evidence linking ocean forcing and megadroughts outside the Medieval Climate Anomaly
The warming trend over the last century in the northern hemisphere (NH) was interrupted by cooling from ad 1940 to 1975, a period during which the southern hemisphere experienced pronounced warming. ...The cause of these departures from steady warming at multidecadal timescales are unclear; the prevailing explanation is that they are driven by non-uniformity in external forcings but recent models suggest internal climate drivers may play a key role. Paleoclimate datasets can help provide a long-term perspective. Here we use tree-rings to reconstruct New Zealand mean annual temperature over the last 550 years and demonstrate that this has frequently cycled out-of-phase with NH mean annual temperature at a periodicity of around 30-60 years. Hence, observed multidecadal fluctuations around the recent warming trend have precedents in the past, strongly implicating natural climate variation as their cause. We consider the implications of these changes in understanding and modelling future climate change.
One underrecognized adverse event of clozapine is the emergence or worsening of obsessive-compulsive symptoms (OCS). OCS, particularly violent thoughts, can be inaccurately described as psychosis and ...result in a misdiagnosis. We report a case of a 42-year-old man, initially diagnosed with schizoaffective, who was placed on clozapine for the management of “violent delusions.” However, clozapine led to a worsening of these violent thoughts resulting in suicidal ideation and hospitalization. After exploration of the intrusive thoughts and noting these to be egodystonic, clearly disturbing, and time consuming, an alternative diagnosis of obsessive-compulsive disorder (OCD) was made. Clozapine was inevitably discontinued resulting in a significant reduction of the intrusive thoughts without emergence of psychosis or adverse events. While an overlapping phenomenology between OCD and psychotic disorders has been described, clozapine and other antiserotonergic antipsychotics have been implicated with the emergence or worsening of OCS. Unique to our case is that the patient’s obsessions had been treated as psychosis leading to the inadequate treatment of his primary illness, OCD. This case highlights the potential for OCD to masquerade as a psychotic disorder and reminds clinicians that clozapine may worsen OCS.
The occurrence of the Medieval Warm Period (MWP) in the Southern Hemisphere is uncertain because of the paucity of well‐dated, high‐resolution paleo‐temperature records covering the past 1,000 years. ...We describe a new tree‐ring reconstruction of Austral summer temperatures from the South Island of New Zealand, covering the past 1,100 years. This record is the longest yet produced for New Zealand and shows clear evidence for persistent above‐average temperatures within the interval commonly assigned to the MWP. Comparisons with selected temperature proxies from the Northern and Southern Hemispheres confirm that the MWP was highly variable in time and space. Regardless, the New Zealand temperature reconstruction supports the global occurrence of the MWP.
To assess the sensitivity of New Zealand tree lines to climate warming, we compared the tree-ring growth characteristics and temperature relationships of silver beech (Nothofagus menziesii (Hook. f.) ...Oerst) at two elevations, ca. 1200 m (tree line) and ca. 1100 m. Modelled relationships between climate series and tree rings indicated that the main climatic control on tree growth was current summer temperatures. Nevertheless, temperatures during earlier seasons can influence tree growth, pointing to a complex relationship between radial growth and climate at tree line. Overall, the similarity in the growth-temperature relationships for trees at both elevations indicated that high-altitude N. menziesii forests should be useful for examining the impact of climate warming on tree growth. However, the level of common growth variation was greater in the below tree line chronologies, suggesting that other factors, including natural disturbance, may affect or compete with the influence of temperature on tree-ring growth at tree line. Despite the importance of summer temperatures for tree growth at or near tree line and the reported increase in summer temperatures since 1950 in New Zealand, ring widths have not increased in recent decades. We conclude, therefore, that in these N. menziesii tree-line forests there has been no detectable tree-ring growth response to climate warming.
Celotno besedilo
Dostopno za:
BF, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
This international guideline proposes improving clozapine package inserts
worldwide by using ancestry-based dosing and titration. Adverse drug reaction
(ADR) databases suggest that clozapine ...is the third most toxic drug in the
United States (US), and it produces four times higher worldwide pneumonia
mortality than that by agranulocytosis or myocarditis. For trough steady-state
clozapine serum concentrations, the therapeutic reference range is narrow, from
350 to 600 ng/mL with the potential for toxicity and ADRs as
concentrations increase. Clozapine is mainly metabolized by CYP1A2 (female
non-smokers, the lowest dose; male smokers, the highest dose). Poor metabolizer
status through phenotypic conversion is associated with co-prescription of
inhibitors (including oral contraceptives and valproate), obesity, or
inflammation with C-reactive protein (CRP) elevations. The Asian population
(Pakistan to Japan) or the Americas’ original inhabitants have lower
CYP1A2 activity and require lower clozapine doses to reach concentrations of
350 ng/mL. In the US, daily doses of
300–600 mg/day are recommended. Slow personalized
titration may prevent early ADRs (including syncope, myocarditis, and
pneumonia). This guideline defines six personalized titration schedules for
inpatients: 1) ancestry from Asia or the original people from the Americas with
lower metabolism (obesity or valproate) needing minimum therapeutic dosages of
75–150 mg/day, 2) ancestry from Asia or the original
people from the Americas with average metabolism needing
175–300 mg/day, 3) European/Western Asian
ancestry with lower metabolism (obesity or valproate) needing
100–200 mg/day, 4) European/Western Asian
ancestry with average metabolism needing 250–400 mg/day,
5) in the US with ancestries other than from Asia or the original people from
the Americas with lower clozapine metabolism (obesity or valproate) needing
150–300 mg/day, and 6) in the US with ancestries other
than from Asia or the original people from the Americas with average clozapine
metabolism needing 300–600 mg/day. Baseline and weekly
CRP monitoring for at least four weeks is required to identify any inflammation,
including inflammation secondary to clozapine rapid titration.
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