Association between cannabis use and symptom dimensions in schizophrenia spectrum disorders: an individual participant data meta-analysis on 3053 individuals

Background: The association between cannabis use and positive symptoms in schizophrenia spectrum disorders is well documented, especially via meta-analyses. Yet, findings are inconsistent regarding negative symptoms, while other dimensions such as disorganization, depression, and excitement, have not been investigated. In addition, meta-analyses use aggregated data discarding important confounding variables which is a source of bias. Methods: PubMed, ScienceDirect and PsycINFO were used to search for publications from inception to September 27, 2022. We contacted the authors of relevant studies to extract raw datasets and perform an Individual Participant Data meta-analysis (IPDMA). Inclusion criteria were: psychopathology of individuals with schizophrenia spectrum disorders assessed by the Positive and Negative Syndrome Scale (PANSS); cannabis-users had to either have a diagnosis of cannabis use disorder or use cannabis at least twice a week. The main outcomes were the PANSS subscores extracted via the 3-factor (positive, negative and general) and 5-factor (positive, negative, disorganization, depression, excitement) structures. Preregistration is accessible via Prospero: ID CRD42022329172. Findings: Among the 1149 identified studies, 65 were eligible and 21 datasets were shared, totaling 3677 IPD and 3053 complete cases. The adjusted multivariate analysis revealed that relative to non-use, cannabis use was associated with higher severity of positive dimension (3-factor: Adjusted Mean Difference, aMD = 0.34, 95% Confidence Interval, CI = [0.03; 0.66]; 5-factor: aMD = 0.38, 95% CI = [0.08; 0.63]), lower severity of negative dimension (3-factor: aMD = -0.49, 95% CI [-0.90; -0.09]; 5-factor: aMD = -0.50, 95% CI = [-0.91; -0.08]), higher severity of excitement dimension (aMD = 0.16, 95% CI = [0.03; 0.28]). No association was found between cannabis use and disorganization (aMD = -0.13, 95% CI = [-0.42; 0.17]) or depression (aMD = -0.14, 95% CI = [-0.34; 0.06]). Interpretation: No causal relationship can be inferred from the current results. The findings could be in favor of both a detrimental and beneficial effect of cannabis on positive and negative symptoms, respectively. Longitudinal designs are needed to understand the role of cannabis is this association. The reported effect sizes are small and CIs are wide, the interpretation of findings should be taken with caution

Ocean circulation in the Toarcian (Early Jurassic), a key control on deoxygenation and carbon burial on the European Shelf

The Toarcian Oceanic Anoxic Event (T-OAE, ∼183 My) was a long-lasting episode of ocean deoxygenation during the Early Jurassic. The event is related to a period of global warming and characterized by major perturbations to the hydrological and carbon cycles with high rates of organic matter burial in shelf seas. Ocean circulation during the Toarcian and its influence on marine biogeochemical cycles are still not fully understood. Here,we assess the spatial extent of anoxia in the NW Tethys Ocean during the T-OAE, the relationship with ocean circulation and the impact on organic carbon burial, using new and existing sedimentary records from the European Epicontinental Shelf (EES) in combination with general circulation model results. We demonstrate that bottom waters on the southwestern part of the shelf were mainly oxic during the T-OAE, while those in the northeastern basins were mostly anoxic or even sulfidic. Results for two ocean-atmosphere models (FOAM and MITgcm) suggest the presence of a strong clockwise gyre over the EES, which brought oxygenated equatorial waters from the Tethys Ocean to the southern shelf. The northward limb of the gyre was significantly weakened due to the rough bathymetry of the northern shelf, making this relative small region highly sensitive to local ocean stratification. These sluggish ocean dynamics promoted bottom water anoxia and enhanced burial of organic carbon in the northeastern basins, which accounted for 3–5% of the total carbon extracted from the ocean-atmosphere system as recorded by the positive carbon isotope shift

Does dietary tocopherol level affect fatty acid metabolism in fish?

Fish are a rich source of the n-3 polyunsaturated fatty acids (PUFA), particularly the highly unsaturated fatty acids (HUFA), eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic (DHA; 22:6n-3) acids, which are vital constituents for cell membrane structure and function, but which are also highly susceptible to attack by oxygen and other organic radicals. Resultant damage to PUFA in membrane phospholipids can have serious consequences for cell membrane structure and function, with potential pathological effects on cells and tissues. Physiological antioxidant protection involves both endogenous components, such as free radical scavenging enzymes, and exogenous dietary micronutrients including tocopherols and tocotrienols, the vitamin E-type compounds, widely regarded as the primary lipid soluble antioxidants. The antioxidant activities of tocopherols are imparted by their ability to donate their phenolic hydrogen atoms to lipid (fatty acid) free radicals resulting in the stabilisation of the latter and the termination of the lipid peroxidation chain reaction. However, tocopherols can also prevent PUFA peroxidation by acting as quenchers of singlet oxygen. Recent studies on marine fish have shown correlations between dietary and tissue PUFA/tocopherol ratios and incidence of lipid peroxidation as indicated by the levels of TBARS and isoprostanes. These studies also showed that feeding diets containing oxidised oil significantly affected the activities of liver antioxidant defence enzymes and that dietary tocopherol partially attenuated these effects. However, there is evidence that dietary tocopherols can affect fatty acid metabolism in other ways. An increase in membrane PUFA was observed in rats deficient in vitamin E. This was suggested to be due to over production of PUFA arising from increased activity of the desaturation/elongation mechanisms responsible for the synthesis of PUFA. Consistent with this, increased desaturation of 18:3n-3 and 20:5n-3 in hepatocytes from salmon fed diets deficient in tocopherol and/or astaxanthin has been observed. Although the mechanism is unclear, tocopherols may influence biosynthesis of n-3PUFA through alteration of cellular oxidation potential or “peroxide tone”

Cone photoreceptor heterogeneity in the primate retina

Thesis (Ph.D.)--University of Washington, 2018Human vision commences when light is transduced to a neural signal. In daylight, this occurs predominantly within cone photoreceptors. Does this transduction occur identically for all light inputs? The work in this thesis addresses this question as well as the role of phototransduction in controlling downstream signals in the visual system. Chapter 2 focuses on heterogeneity in the transduction of light across wavelengths due to differences in short-, medium-, and long- wavelength sensitive cone photoreceptors. Chapter 3 elaborates on heterogeneity in transduction of inputs across visual space arising from differences in cones across retinal eccentricity. Chapter 4 begins to explore an instance where cone signals directly control retinal output. Together, this body of work aims to provide an appreciation for heterogeneity in signal transduction within cones throughout the primate retina and link cone properties to both retinal output and perception

Data from: S-cone photoreceptors in the primate retina are functionally distinct from L and M cones

Daylight vision starts with signals in three classes of cone photoreceptors sensitive to short (S), middle (M), and long (L) wavelengths. Psychophysical studies show that perceptual sensitivity to rapidly varying inputs differs for signals originating in S cones versus L and M cones; notably, S-cone signals appear perceptually delayed relative to L- and M-cone signals. These differences could originate in the cones themselves or in the post-cone circuitry. To determine if the cones could contribute to these and related perceptual phenomena, we compared the light responses of primate S, M, and L cones. We found that S cones generate slower light responses than L and M cones, show much smaller changes in response kinetics as background-light levels increase, and are noisier than L and M cones. It will be important to incorporate these differences into descriptions of how cone signaling shapes human visual perception

Source data

This folder has four matlab .mat files. This should contain raw data for Figs. 1, 2, 4, 5, 6, 7. It isn't all data for all the figures, but there is example data for those. flash_responses.mat has data from all of Fig 1 and parts of Figs. 2 and 5; sbc_examples.mat has data for figure 6; cellular_noise.mat has data for figure 7; cone_linear_filters.mat has data from figure 4. Readme file is in the folder

Environmental and hydrological changes at the Paleocene-Eocene boundary in the terrestrial sediments of the Cap d'Ailly core (Upper Normandy, France)

International audienceThe Paleocene-Eocene Thermal Maximum (PETM, 55.8 Ma, Aubry et al., 2007) is regarded as one of the most rapid global warming of the Cenozoic era, with temperature increase of 4-8°C in about 10-20 ka. Thus, it is often proposed as a potential analogue of future climatic conditions expected in the screenplays provided by the International Panel on Climate Change (IPCC). The PETM is recorded in both marine and terrestrial deposits by an abrupt negative Carbon Isotope Excursion (CIE) associated with other sedimentary and biological anomalies. The consequences of the PETM in terrestrial environments are less documented than in marine ones. This limits our regional- and global-scale understanding of the impact of such a drastic climate change on continents and the ecosystems response. This study focuses on the Cap d'Ailly core (Seine-Maritime, France) drilled by the BRGM in 2008 in the southern part of the Dieppe-Hampshire Basin, an area where the PETM has already been attested in a few sections by the presence of the CIE and the Apectodinium acme (Magioncalda et al, 2001; Dupuis et al, 2006; Storme et al, 2012). These sections consist of terrestrial and lagoonal organic matter-rich deposits that are typical of the Sparnacian facies (latest Paleocene - earliest Eocene; Aubry et al., 2005). The lower part of the "Sparnacian" is dominated by fluvial, lacustrine and swamp deposits such as marls and lignites. It is overlain by two units of lagoonal deposits rich in shell debris separated by terrestrial deposits. The uppermost part of the section is constituted by a 1 m-thick marine clay rich in glauconite (Dupuis & Steurbaut, 1987). Global organic geochemical, palynofacies and isotopic analyses reveal that the onset of the CIE is located in the lowermost swamp deposits. The total organic carbon ranges from 0.02 % for paleosols to 43 % for lignite beds. The organic matter is mainly of Type III (terrestrial higher plants) and immature. These interpretations are reinforced by palynofacies observations that show a large amount of ligno-cellulosic phytoclasts in many samples. In marine and lagoonal deposits, the presence of many Apectodinium specimens would suggest the continuation of the PETM up to the top of the Sparnacian deposits, although this has to be confirmed by carbon isotopes analyses. Palynofacies, distribution of specific lipid biomarkers as well as their hydrogen and carbon isotopic compositions show important changes coincident with the CIE onset. This is consistent with important environmental and hydrological changes in the Cap d'Ailly area during the earliest Eocene that could be linked to the PETM climatic change

Paleoclimatic changes recorded by δD of n-alkanes and δ15Norg in a continental section of central Asia (Early Jurassic)

International audienceMajor paleoenvironmental changes have been documented during the Early Jurassic (e.g. Morard et al., 2003; Suan et al., 2008). Most studies were carried out on European marine sediments, with little information on the environmental conditions that prevailed in terrestrial ecosystems. Here we present results on a continental section from Taskomirsai (South Kazakhstan) showing a succession of sedimentary cycles made of lignites, clayey layers and silty-sandstones most probably deposited in a fluvial/lacustrine environment with nearby swampy areas. Rock-Eval pyrolysis indicates an immature Type-III organic matter. A multi-isotope approach based on bulk organic nitrogen isotopes (δ 15 Norg) and hydrogen isotopic composition (δD) of n-alkanes was developed to document paleoclimatic changes in the area. To the best of our knowledge, it is the first time that these proxies are combined for a paleoclimatic approach in the Early Jurassic. In the literature, compound-specific δD is usually used to reconstruct paleohydrological conditions (Sachse et al., 2012). In the same way, δ 15 Norg measured on modern or Quaternary plants has been positively correlated with temperature and negatively correlated with precipitations (e.g. Austin and Vitousek, 1998; Liu and Wang, 2008). Then, these concepts were successfully used to evidence humid/dry cycles around the Paleocene-Eocene transition (Storme et al., 2012). In Taskomirsai, δ 15 Norg values ranged from 0.5‰ to 4.5‰. The lowest values are found in lignite beds and interpreted as humid periods, whereas the highest ones are recorded in clayey layers and suggest drier periods. The δD values of n-alkanes (C17 to C35) ranged from-248‰ to-151‰. Two groups of n-alkanes were distinguished based on their chain length and their δD values: an aquatic group (C17 to C23;-198‰ in average) and a terrestrial one (C25 to C35;-183‰ in average). In the aquatic group, low δD values in lignites (-219 17‰; n=10) suggest humid and/or cool climate during their formation, whereas high values in clayey layers (-179 13‰; n=6) suggest a drier and/or warmer climate. Based on main trends in the n-alkanes δD values, two " climatic units " are proposed named Unit 1 and Unit 2 (Figure 1). Decreasing δD values in Unit 1, recorded in the aquatic pool, suggest a cooling/humid climate trend (Figure 1). In contrast, drier/warmer conditions, inferred from high δD values, took over in Unit 2. δD values also suggest paleoclimatic variations at higher frequency than the two main trends described above. They seem to be linked with the sedimentary cycles. This finding rules out an autocyclic control on the sedimentation, which would have been generated by local sedimentary processes (e.g. moving channels of rivers). Thus, an allocyclic control driven by climate is most likely

High frequency floral changes at the Paleocene–Eocene boundary revealed by comparative biomarker and palynological studies

International audienceThe Cap d'Ailly area (Upper Normandy, France) shows several terrestrial–lagoonal sections recording the negative carbon isotope excursion (CIE) associated with the Paleocene–Eocene Thermal Maximum (PETM; 55.8 Ma). A study of the biomarkers and spore/pollen content of the Vasterival section gave com-plementary information on paleofloral changes that occurred around the Paleocene–Eocene (P–E) bound-ary. Aliphatic hydrocarbon fractions revealed a high abundance of vascular plant biomarkers, including tricyclic diterpanes derived from conifers, fernenes derived from ferns and des-A-triterpenes derived from angiosperms. Whereas the vegetation of the depositional environment surroundings seemed alter-nately dominated by ferns and angiosperms (revealed from biomarkers), the regional flora seemed dom-inated strictly by angiosperms such as Juglandaceae (revealed by pollen). Spore/pollen assemblages revealed no major turnover in the paleovegetation, but slight variation in vegetation composition. How-ever, both biomarkers and spores/pollen exhibited two intervals of rapid floral change: the first occurred around the P–E boundary and the second at the top of the strictly terrestrial unit that coincides with a marine transgression. Comparison of the data with published paleoclimatic results, obtained from the same samples, indicated that the first interval of floral change correlates with strong paleohydrological perturbations, whereas the second is linked to an increasing marine influence

Changements hydrologiques et environnementaux dans le Noyonnais à la limite Paléocène-Éocène (Oise).

National audienceLe maximum thermique de la limite Paléocène-Eocène (PETM : Paleocene-Eocene Thermal Maximum) fut un réchauffement global et brusque qui s'est produit il y a 55,8 Ma et dura entre 170 et 220 ka (Röhl et al., 2007). Cet évènement hyperthermique est associé à une excursion isotopique négative du carbone (CIE : Carbon Isotope Excursion) qui est notamment enregistrée par la matière organique (MO) terrestre et marine (Aubry et al., 2007). Actuellement, les effets du PETM sur les environnements continentaux sont encore mal connus. De récentes études de la MO de sédiments côtiers du Paléocène-Eocène (P-E) du Bassin de Dieppe-Hampshire ont révélé de forts changements environnementaux et climatiques associés à la limite P-E (Storme et al., 2012; Garel et al., 2013). Afin de déterminer si ces changements sont locaux ou régionaux, 2 carottes forées dans le Noyonnais du bassin de Paris ont été étudiées (BEAU et PORQ). Elles montrent des sédiments plus continentaux que ceux du Bassin de Dieppe-Hampshire, tels que des sables fluviatiles et des argiles de plaine d'inondation, tous riches en MO. Les analyses du δ13C de la MO ont révélé que la CIE s'étend sur 3 m d'épaisseur dans la carotte BEAU et sur 12 m d'épaisseur dans la carotte PORQ. L'observation des palynofaciès a montré la dominance de la MO d'origine végétale supérieure. Cependant, des pics de concentration de MO algaires sont aussi observés au sein du PETM dans PORQ. Les biomarqueurs moléculaires, quantifiés par GC-MS, ont montré que les fractions aliphatiques des 2 carottes sont dominées par les n-alcanes, les hopanes et les triterpènes pentacycliques. Dans les 2 sites, le début du PETM coïncide avec des pics de concentration en biomarqueurs de fougères (p. ex. fernènes), ceux-ci étant même parfois plus abondants que les biomarqueurs d'angiospermes (p. ex. oleanènes) à PORQ. Cette carotte est surtout marquée par l'alternance de pics de biomarqueurs de fougères et d'angiospermes au sein de la CIE. Le δD des n-alcanes, analysé par GC-irMS, montre, à BEAU, une décroissance continue des valeurs de la fin du Paléocène jusqu'au sommet de la carotte, ce qui indique un passage progressif à des conditions plus humides. A PORQ, ce changement, qui est aussi observé, est suivi par un retour progressif à des conditions plus sèches à la fin du PETM. Finalement, la comparaison de ces résultats avec ceux publiés dans le Bassin de Dieppe-Hampshire (Garel et al., 2013 ; Garel et al., soumis) montre que, si certains des changements environnementaux et hydrologiques sont similaires dans les deux secteurs, d'autres sont complètement opposés. Ceci suggère que les effets d'une brusque crise climatique sont très variables d'une région à l'autre