A marine record of Patagonian ice sheet changes over the past 140,000 years

Terrestrial glacial records from the Patagonian Andes and New Zealand Alps document quasi-synchronous Southern Hemisphere-wide glacier advances during the late Quaternary. However, these records are inherently incomplete. Here, we provide a continuous marine record of western-central Patagonian ice sheet (PIS) extent over a complete glacial-interglacial cycle back into the penultimate glacial (~140 ka). Sediment core MR16-09 PC03, located at 46°S and ~150 km offshore Chile, received high terrestrial sediment and meltwater input when the central PIS extended westward. We use biomarkers, foraminiferal oxygen isotopes, and major elemental data to reconstruct terrestrial sediment and freshwater input related to PIS variations. Our sediment record documents three intervals of general PIS marginal fluctuations, during Marine Isotope Stage (MIS) 6 (140 to 135 ka), MIS 4 (~70 to 60 ka), and late MIS 3 to MIS 2 (~40 to 18 ka). These higher terrigenous input intervals occurred during sea-level low stands, when the western PIS covered most of the Chilean fjords, which today retain glaciofluvial sediments. During these intervals, high-amplitude phases of enhanced sediment supply occur at millennial timescales, reflecting increased ice discharge most likely due to a growing PIS. We assign the late MIS 3 to MIS 2 phases and, by inference, older advances to Antarctic cold stages. We conclude that the increased sediment/meltwater release during Southern Hemisphere millennial-scale cold phases was likely related to higher precipitation caused by enhanced westerly winds at the northwestern margin of the PIS. Our records complement terrestrial archives and provide evidence for PIS climate sensitivity.

Five million years of Antarctic Circumpolar Current strength variability

The Antarctic Circumpolar Current (ACC) represents the world's largest ocean-current system and affects global ocean circulation, climate and Antarctic ice-sheet stability1-3. Today, ACC dynamics are controlled by atmospheric forcing, oceanic density gradients and eddy activity4. Whereas palaeoceanographic reconstructions exhibit regional heterogeneity in ACC position and strength over Pleistocene glacial-interglacial cycles5-8, the long-term evolution of the ACC is poorly known. Here we document changes in ACC strength from sediment cores in the Pacific Southern Ocean. We find no linear long-term trend in ACC flow since 5.3 million years ago (Ma), in contrast to global cooling9 and increasing global ice volume10. Instead, we observe a reversal on a million-year timescale, from increasing ACC strength during Pliocene global cooling to a subsequent decrease with further Early Pleistocene cooling. This shift in the ACC regime coincided with a Southern Ocean reconfiguration that altered the sensitivity of the ACC to atmospheric and oceanic forcings11-13. We find ACC strength changes to be closely linked to 400,000-year eccentricity cycles, probably originating from modulation of precessional changes in the South Pacific jet stream linked to tropical Pacific temperature variability14. A persistent link between weaker ACC flow, equatorward-shifted opal deposition and reduced atmospheric CO2 during glacial periods first emerged during the Mid-Pleistocene Transition (MPT). The strongest ACC flow occurred during warmer-than-present intervals of the Plio-Pleistocene, providing evidence of potentially increasing ACC flow with future climate warming.

Early hyperdopaminergic state following sub-thalamic nucleus deep brain stimulation in Parkinson disease

BACKGROUND

Hyperdopaminergic state (HS), especially impulse control behaviors (ICBs), are not rare in Parkinson's disease (PD). Controversial data regarding HS prevalence one year following sub-thalamic nucleus deep brain stimulation (STN-DBS) are reported.

OBJECTIVE

Our objectives were to describe early postoperative HS (PoOHS) including ICBs, hypomania and psychotic symptoms during the first 3 months following STN-DBS (V1) and their prognosis at 1 year (V2).

METHODS

This descriptive study included 24 PD patients treated successively with bilateral STN-DBS between 2017 and 2019. The primary endpoint was prevalence of PoOHS at V1 according to the Ardouin Scale of Behaviour in Parkinson's Disease.

RESULTS

Prior to STN-DBS (V0), 25% patients had HS (only ICBs) whereas at V1 (during the 3 first months), 10 patients (41.7%) had one or several HS (P=0.22) (de novo in 29.2%): 7 (29.2%) ICBs, 4 (16.7%) hypomanic mood, 1 (4.7%) psychotic symptoms. At V2, all V0 and V1 HS had disappeared, while 1 patient (4.2%) presented de novo HS (P<0.01). No correlation was found between the occurrence of PoOHS at V1 and any V0 data. Higher levodopa equivalent dose of dopamine agonists at V1 was correlated with ICB at V1 (P=0.04).

CONCLUSION

We found that early PoOHS are frequent in PD after STN-DBS, mostly de novo, with ICBs and hypomania being the most frequent. Despite a good prognosis of PoOHS at one year, our work emphasizes the importance of both a cautious adjustment of dopamine agonist doses and a close non-motor monitoring pre- and post-STN-DBS in PD.

Element mobility related to rock weathering and soil formation at the westward side of the southernmost Patagonian Andes

Rock weathering and pedogenesis are fundamental processes for element mobility in terrestrial bio-geochemical cycles and for the regulation of primary productivity in adjacent coastal marine ecosystems. Here, soils developed from volcanic ash under extreme climate conditions could play a particular role. We therefore investigated rock weathering, soil formation and the associated mobilization of trace elements and micronutrients in a pristine South Patagonian ecosystem. Weathered and unweathered basement lithologies, tephra of the 4.216 kyrs BP Mt. Burney eruption and four soil profiles are considered. The approach combines mineralogical (XRD, SEM) and inorganic geochemical (XRF, ICP-OES/MS) with organic geochemical analyses (TOC, TN, δ¹³C, δ¹⁵N, DOC extracts) of representative samples. Chemical weathering is quantified by mass balance calculations and ¹⁴C age constraints allow a correlation of pedogenic processes with the paleoenvironmental history of the area. Our data document that pedogenesis with initial peat formation occurred since ~2.5 kyrs BP. In these acidic peaty Andosols, intensive alteration of volcanic glass mobilized large quantities of elements, considerably surpassing leachates provided by basement rock weathering. Clay production is limited in favor of the formation of amorphous Al- and crystalline Fe-(hydr)oxides. However, tephra alteration, soil organic matter turnover rates, enhanced dissolved organic carbon export, and Fe-/Al-(hydr)oxide precipitation are closely linked and ultimately controlled by rainfall-induced water-level fluctuations, highlighting the dominant influence of the southern westerly wind belt. The transport of mobilized trace elements and micronutrients adsorbed onto suspended colloids (dissolved organic carbon, Al-humus complexes and Fe-(hydr)oxides) is redox-pH-dependent, highly variable and ultimately regulated by westerly intensity. Broader implications of this work include a new perspective on the climate-controlled micronutrient delivery for primary productivity in South Patagonian fjords, which is strongly affected by Andosol formation. Furthermore, a careful evaluation of 'ordinary' geochemical proxies in regional paleoenvironmental archives is needed to account for these unique pedogenic processes.

Orbital- and millennial-scale Antarctic Circumpolar Current variability in Drake Passage over the past 140,000 years

The Antarctic Circumpolar Current (ACC) plays a crucial role in global ocean circulation by fostering deep-water upwelling and formation of new water masses. On geological time-scales, ACC variations are poorly constrained beyond the last glacial. Here, we reconstruct changes in ACC strength in the central Drake Passage in vicinity of the modern Polar Front over a complete glacial-interglacial cycle (i.e., the past 140,000 years), based on sediment grain-size and geochemical characteristics. We found significant glacial-interglacial changes of ACC flow speed, with weakened current strength during glacials and a stronger circulation in interglacials. Superimposed on these orbital-scale changes are high-amplitude millennial-scale fluctuations, with ACC strength maxima correlating with diatom-based Antarctic winter sea-ice minima, particularly during full glacial conditions. We infer that the ACC is closely linked to Southern Hemisphere millennial-scale climate oscillations, amplified through Antarctic sea ice extent changes. These strong ACC variations modulated Pacific-Atlantic water exchange via the "cold water route" and potentially affected the Atlantic Meridional Overturning Circulation and marine carbon storage.

Survey on patients' organisations' knowledge and position paper on screening for inherited neuromuscular diseases in Europe

BACKGROUND

The development of new genetic testing methods and the approval of the first treatments raises questions regarding when and how to perform screening for inherited neuromuscular conditions. Screening directives and access to the different techniques is not uniform across Europe. The patient advisory board of the European reference network for rare neuromuscular diseases (NMD) conducted a qualitative study to understand the state of play of screening for inherited NMD in Europe and patients' needs.

RESULTS

We collected answers from 30 patient organisations (POs) from 18 European countries. Fifteen acknowledge the existence of pre-implantation genetic diagnosis in their country. Regarding prenatal screening, we had 25 positive answers and 5 negative ones. Twenty-four POs mentioned that newborn screening was available in their country. We had some contradictory answers from POs from the same country and in some cases; diseases said to be part of the screening programmes were not hereditary disorders. Twenty-eight organisations were in favour of screening tests. The reasons for the two negative answers were lack of reimbursement and treatment, religious beliefs and eventual insurance constrains. Most POs (21) were in favour of systematic screening with the option to opt-out. Regarding the timing for screening, "at birth", was the most consensual response. The main priority to perform screening for NMDs was early access to treatment, followed by shorter time to diagnostic, preventive care and genetic counselling.

CONCLUSIONS

This is the first study to assess knowledge and needs of POs concerning screening for NMDs. The knowledge of POs regarding screening techniques is quite uneven. This implies that, even in communities highly motivated and knowledgeable of the conditions they advocate for, there is a need for better information. Differences in the responses to the questions "how and when to screen" shows that the screening path depends on the disease and the presence of a disease modifying treatment. The unmet need for screening inherited NMDs should follow an adaptive pathway related to the fast moving medical landscape of NMDs. International coordination leading to a common policy would certainly be a precious asset tending to harmonize the situation amongst European countries.

A circumpolar dust conveyor in the glacial Southern Ocean

The increased flux of soluble iron (Fe) to the Fe-deficient Southern Ocean by atmospheric dust is considered to have stimulated the net primary production and carbon export, thus promoting atmospheric CO₂ drawdown during glacial periods. Yet, little is known about the sources and transport pathways of Southern Hemisphere dust during the Last Glacial Maximum (LGM). Here we show that Central South America (~24‒32°S) contributed up to ~80% of the dust deposition in the South Pacific Subantarctic Zone via efficient circum-Antarctic dust transport during the LGM, whereas the Antarctic Zone was dominated by dust from Australia. This pattern is in contrast to the modern/Holocene pattern, when South Pacific dust fluxes are thought to be primarily supported by Australian sources. Our findings reveal that in the glacial Southern Ocean, Fe fertilization critically relies on the dynamic interaction of changes in dust-Fe sources in Central South America with the circumpolar westerly wind system.

Dust deposition brings iron that fuels ocean productivity, a connection impacting climate over geological time. Here the authors use sediment cores to show that in contrast to dynamics today, during the last glacial maximum westerly winds shuttled dust from Australia and South America around Antarctica and into the South Pacific.

P14.87 Leptomeningeal dissemination in high grade glioma: Correlation of MRI, cytology and standard CSF indices

BACKGROUND

Only few studies report the incidence of leptomeningeal dissemination (LMD) in patients with high grade glioma (HGG), although LMD is not a rare condition of recurrence. We aimed to describe the diagnostic features and treatment modalities in a series of patients treated for HGG in our institution.

METHODS

Review of clinical presentation, radiological features and CSF analysis in a case series.

RESULTS

17 patients from our institution were diagnosed with LMD. The diagnosis of LMD was based on magnetic resonance image and/or cerebrospinal fluid (CSF) analysis. The spectrum of clinical presentation was broad, mainly intracranial hypertension, impaired general condition, pain, worsening of pre-existing symptoms, and epileptic seizures. Median time from onset of clinical deterioration to diagnosis of LMD was 3 weeks (0–16). Leptomeningial involvement was reported in 6/17 at initial MRI reading, whereas reassessment with careful comparison to previous MRI showed signs of LMD in all patients. CSF analysis revealed pleocytosis (11/17), high proteinorrachia (13/17), elevated lactate levels (15/16), low glucose levels (5/17), and increased CSF pressure (5/9). Nevertheless, diagnostic accuracy of initial CSF cytological analysis was low (2/17). A reassessment of the specimen by an experienced neuropathologist disclosed 1 additional positive and 1 additional suspect cytology. After diagnosis of LMD, salvage treatments comprised Bevacizumab, Lomustine, Fotemustine, liposomal cytarabine and best supportive care. The median overall survival after the diagnosis was 3 months.

DISCUSSION AND CONCLUSIONS

LMD in HGG is not a rare condition of recurrence, and its outcome is poor. It remains a diagnostic challenge, as it may be overlooked on MRI follow-up at its early stage. In case of clinical progression with no overt cause reported on MRI, we recommend careful second MRI reading. In case of doubt lumbar puncture should be performed in order to prove LMD and eliminate infection (i.e. HSV). Upon standard CSF indices, elevated lactate levels should give rise to the suspicion of LMD. Cytological CSF analysis seems to be of low diagnostic yield: This may be improved by faster processing after sampling and by standardized workup including staining with IDH, GFAP and Olig2.

OS1.3 Tumor cell-free DNA detection in CSF for primary CNS lymphoma diagnosis

BACKGROUND

Primary CNS lymphoma (PCNSL) is a rare disease accounting for around 3% of the primary brain tumors. In the vast majority of cases, PCNSL are classified as diffuse large B-cell lymphoma according to the WHO classification. The diagnosis is based on cranial MRI, in combination with a brain biopsy. In case of classical MRI findings, the identification of lymphoma cells in the cerebrospinal (CSF) or vitreous fluid by cytology and flow cytometry might obviate brain biopsy. The presence of the somatic mutation p.Leu265Pro (L265P) in MYD88 is detectable in 50 to 80% of PCNSL, and might also be helpful to confirm the diagnosis. The aim of our study was to evaluate the contribution of a highly sensitive digital droplet PCR, targeting the mutation L265P MYD88, for the detection of tumoral circulating DNA from CSF supernatant.

MATERIAL AND METHODS

We identified 9 PCNSL expressing the L265P mutation at diagnosis or relapse. The mutation was found by an allele specific PCR technique either on biopsy or in CSF cells. Circulating DNA was isolated from CSF supernatant with the « QiaAmp® circulating nucleic acid» kit. The quantity of DNA collected was estimated by quantitative PCR for a reference gene (albumine) with 7900HT (Life technologies™) device. Subsequently, the L265P MYD88 mutation was quantified by digital droplet PCR Biorad™: The droplets generated were amplified by PCR, detected with the QX200 Reader, and analyzed with the QuantaSoft™ software.

RESULTS

The circulating DNA concentration was low, varying between 0 and 2.2 ng/mL of CSF. However, the mutation was detected in the circulating DNA from CSF supernatant in 6 out of 9 cases (66%). The fractional abundance varied from 2.6 to 85%. In 3 cases, the mutation was detected even though cytology and flow cytometry did not reveal leptomeningeal disease. For 3 other cases, the mutation was not detected: The genome copy number was below 1 copy/µL, indicating a low analytical sensitivity for theses samples.

CONCLUSION

This study shows that circulating DNA is present in low concentration in CSF and can be amplified by a sensitive digital PCR for the L265P MYD88 mutation. The detection of circulating PCNSL DNA in CSF is possible and might be used to improve the non-invasive diagnosis of PCNSL. It might also help to select patients for targeted therapies.

Breakup of last glacial deep stratification in the South Pacific

Stratification of the deep Southern Ocean during the Last Glacial Maximum is thought to have facilitated carbon storage and subsequent release during the deglaciation as stratification broke down, contributing to atmospheric CO₂ rise. Here, we present neodymium isotope evidence from deep to abyssal waters in the South Pacific that confirms stratification of the deepwater column during the Last Glacial Maximum. The results indicate a glacial northward expansion of Ross Sea Bottom Water and a Southern Hemisphere climate trigger for the deglacial breakup of deep stratification. It highlights the important role of abyssal waters in sustaining a deep glacial carbon reservoir and Southern Hemisphere climate change as a prerequisite for the destabilization of the water column and hence the deglacial release of sequestered CO₂ through upwelling.

Bacteriohopanepolyols along redox gradients in the Humboldt Current System off northern Chile

Marine oxygen minimum zones (OMZs) are characterized by the presence of subsurface suboxic or anoxic waters where diverse microbial processes are responsible for the removal of fixed nitrogen. OMZs have expanded over past decades and are expected to continue expanding in response to the changing climate. The implications for marine biogeochemistry, particularly nitrogen cycling, are uncertain. Cell membrane lipids (biomarkers), such as bacterial bacteriohopanepolyols (BHPs) and their degradation products (hopanoids), have distinctive structural attributes that convey information about their biological sources. Since the discovery of fossil hopanoids in ancient sediments, the study of BHPs has been of great biogeochemical interest due to their potential to serve as proxies for bacteria in the geological record. A stereoisomer of bacteriohopanetetrol (BHT), BHT II, has been previously identified in OMZ waters and has as been unequivocally identified in culture enrichments of anammox bacteria, a key group contributing to nitrogen loss in marine OMZs. We tested BHT II as a proxy for suboxia/anoxia and anammox bacteria in suspended organic matter across OMZ waters of the Humboldt Current System off northern Chile, as well as in surface and deeply buried sediments (125-150 ky). The BHT II ratio (BHT II/total BHT) increases as oxygen content decreases through the water column, consistent with previous results from Perú, the Cariaco Basin and the Arabian Sea, and in line with microbiological evidence indicating intense anammox activity in the Chilean OMZ. Notably, BHT II is transported from the water column to surface sediments, and preserved in deeply buried sediments, where the BHT II ratio correlates with changes in δ¹⁵ N sediment values during glacial-interglacial transitions. This study suggests that BHT II offers a proxy for past changes in the relative importance of anammox, and fluctuations in nitrogen cycling in response to ocean redox changes through the geological record.

Radiocarbon constraints on the extent and evolution of the South Pacific glacial carbon pool

During the last deglaciation, the opposing patterns of atmospheric CO2 and radiocarbon activities (Δ(14)C) suggest the release of (14)C-depleted CO2 from old carbon reservoirs. Although evidences point to the deep Pacific as a major reservoir of this (14)C-depleted carbon, its extent and evolution still need to be constrained. Here we use sediment cores retrieved along a South Pacific transect to reconstruct the spatio-temporal evolution of Δ(14)C over the last 30,000 years. In ∼2,500-3,600 m water depth, we find (14)C-depleted deep waters with a maximum glacial offset to atmospheric (14)C (ΔΔ(14)C=-1,000‰). Using a box model, we test the hypothesis that these low values might have been caused by an interaction of aging and hydrothermal CO2 influx. We observe a rejuvenation of circumpolar deep waters synchronous and potentially contributing to the initial deglacial rise in atmospheric CO2. These findings constrain parts of the glacial carbon pool to the deep South Pacific.

Glacial reduction and millennial-scale variations in Drake Passage throughflow

The Drake Passage (DP) is the major geographic constriction for the Antarctic Circumpolar Current (ACC) and exerts a strong control on the exchange of physical, chemical, and biological properties between the Atlantic, Pacific, and Indian Ocean basins. Resolving changes in the flow of circumpolar water masses through this gateway is, therefore, crucial for advancing our understanding of the Southern Ocean's role in global ocean and climate variability. Here, we reconstruct changes in DP throughflow dynamics over the past 65,000 y based on grain size and geochemical properties of sediment records from the southernmost continental margin of South America. Combined with published sediment records from the Scotia Sea, we argue for a considerable total reduction of DP transport and reveal an up to ∼ 40% decrease in flow speed along the northernmost ACC pathway entering the DP during glacial times. Superimposed on this long-term decrease are high-amplitude, millennial-scale variations, which parallel Southern Ocean and Antarctic temperature patterns. The glacial intervals of strong weakening of the ACC entering the DP imply an enhanced export of northern ACC surface and intermediate waters into the South Pacific Gyre and reduced Pacific-Atlantic exchange through the DP ("cold water route"). We conclude that changes in DP throughflow play a critical role for the global meridional overturning circulation and interbasin exchange in the Southern Ocean, most likely regulated by variations in the westerly wind field and changes in Antarctic sea ice extent.

Increased dust deposition in the Pacific Southern Ocean during glacial periods

Dust deposition in the Southern Ocean constitutes a critical modulator of past global climate variability, but how it has varied temporally and geographically is underdetermined. Here, we present data sets of glacial-interglacial dust-supply cycles from the largest Southern Ocean sector, the polar South Pacific, indicating three times higher dust deposition during glacial periods than during interglacials for the past million years. Although the most likely dust source for the South Pacific is Australia and New Zealand, the glacial-interglacial pattern and timing of lithogenic sediment deposition is similar to dust records from Antarctica and the South Atlantic dominated by Patagonian sources. These similarities imply large-scale common climate forcings, such as latitudinal shifts of the southern westerlies and regionally enhanced glaciogenic dust mobilization in New Zealand and Patagonia.

Degradation of Kraft Indulin Lignin by Streptomyces viridosporus and Streptomyces badius

Crawford and collaborators have studied extensively the solubilization of lignocellulose by two Streptomyces species, S. badius and S. viridosporus. Using a condensed industrial lignin essentially devoid of carbohydrates, Indulin AT, as the sole source of carbon, similar results were obtained: (i) the growths of the bacteria were optimum at pH 7.5 to 8.5; (ii) yeast extract was a better source of nitrogen than NH(4)Cl; (iii) the products of the depolymerization of Indulin were soluble, acid-precipitable polymers. When d-glucose was added as a secondary carbon source, it was used preferentially and the production of acid-precipitable polymers began only after the complete depletion of the sugar. On the assumption that the degradation of Indulin was catalyzed by enzymes, proteins found in the culture media and soluble and insoluble intracellular proteins were incubated with Indulin at pH 7.0 at 37 degrees C. Proteins in all fractions from S. badius had ligninolytic activities which, with the exception of those in the intracellular soluble fraction, were increased in the presence of H(2)O(2). In S. viridosporus, both extra- and intracellular soluble activities were found which were not increased by H(2)O(2). The extracellular activity of S. viridosporus was not affected by heat, resisted partially an exposure to pH 1.0, and was completely destroyed by proteolysis.

Methotrexate and liver function: a study of 13 psoriasis cases treated with different cumulative dosages

BACKGROUND

The need and frequency of hepatic biopsies during methotrexate (MTX) therapy are still controversial.

OBJECTIVES

The purpose of this investigation is to assess MTX liver toxicity in patients with psoriasis through percutaneous liver biopsy, and compare liver morphology changes with increasing cumulative dosages (1, 2, 3 and 4 g) of MTX.

RESULTS

Cumulative dosages of 1 to 2 g MTX did not cause significant liver toxicity. From a cumulative dosage of 3 to 4 g, there is fibrosis formation, inflammation enhancement in the portal area and fibrous septa, configuring regenerative nodes.

CONCLUSION

In patients with no risk factors for liver disease, with normal physical examination and liver tests, biopsy can be done after a cumulative MTX dosage of approximately 1 to 1.5 g and repeated for each gram. In patients with risk factors, liver biopsy should be done before use of MTX, or within the first 2 months of treatment at the most, and repeated for each gram of cumulative dosage.

Genomic paleontology provides evidence for two distinct origins of Asian rice (Oryza sativa L.)

The origin of rice domestication has been the subject of debate for several decades. We have compared the transpositional history of 110 LTR retrotransposons in the genomes of two rice varieties, Nipponbare (Japonica type) and 93-11 (Indica type) whose complete sequences have recently been released. Using a genomic paleontology approach, we estimate that these two genomes diverged from one another at least 200,000 years ago, i.e., at a time which is clearly older than the date of domestication of the crop (10,000 years ago, during the late Neolithic). In addition, we complement and confirm this first in silico analysis with a survey of insertion polymorphisms in a wide range of traditional rice varieties of both Indica and Japonica types. These experimental data provide additional evidence for the proposal that Indica and Japonica rice arose from two independent domestication events in Asia.

Antarctic Timing of Surface Water Changes off Chile and Patagonian Ice Sheet Response

Marine sediments from the Chilean continental margin are used to infer millennial-scale changes in southeast Pacific surface ocean water properties and Patagonian ice sheet extent since the last glacial period. Our data show a clear "Antarctic" timing of sea surface temperature changes, which appear systematically linked to meridional displacements in sea ice, westerly winds, and the circumpolar current system. Proxy data for ice sheet changes show a similar pattern as oceanographic variations offshore, but reveal a variable glacier-response time of up to approximately 1000 years, which may explain some of the current discrepancies among terrestrial records in southern South America.

Mediterranean moisture source for an early-Holocene humid period in the northern Red Sea

Paleosalinity and terrigenous sediment input changes reconstructed on two sediment cores from the northernmost Red Sea were used to infer hydrological changes at the southern margin of the Mediterranean climate zone during the Holocene. Between approximately 9.25 and 7.25 thousand years ago, about 3 per thousand reduced surface water salinities and enhanced fluvial sediment input suggest substantially higher rainfall and freshwater runoff, which thereafter decreased to modern values. The northern Red Sea humid interval is best explained by enhancement and southward extension of rainfall from Mediterranean sources, possibly involving strengthened early-Holocene Arctic Oscillation patterns and a regional monsoon-type circulation induced by increased land-sea temperature contrasts. We conclude that Afro-Asian monsoonal rains did not cross the subtropical desert zone during the early to mid-Holocene.

The role of cyclic AMP and its effect on protein kinase A in the mitogenic action of thyrotropin on the thyroid cell

Cyclic AMP has been shown to inhibit cell proliferation in many cell types and to activate it in some. The latter has been recognized only lately, thanks in large part to studies on the regulation of thyroid cell proliferation in dog thyroid cells. The steps that led to this conclusion are outlined. Thyrotropin activates cyclic accumulation in thyroid cells of all the studied species and also phospholipase C in human cells. It activates directly cell proliferation in rat cell lines, dog, and human thyroid cells but not in bovine or pig cells. The action of cyclic AMP is responsible for the proliferative effect of TSH. It accounts for several human diseases: congenital hyperthyroidism, autonomous adenomas, and Graves' disease; and, by default, for hypothyroidism by TSH receptor defect. Cyclic AMP proliferative action requires the activation of protein kinase A, but this effect is not sufficient to explain it. Cyclic AMP action also requires the permissive effect of IGF-1 or insulin through their receptors, mostly as a consequence of PI3 kinase activation. The mechanism of these effects at the level of cyclin and cyclin-dependent protein kinases involves an induction of cyclin D3 by IGF-1 and the cyclic AMP-elicited generation and activation of the cyclin D3-CDK4 complex.

Comparative analysis of QTLs affecting domestication traits between two domesticated x wild pearl millet ( Pennisetum glaucum L., Poaceae) crosses

Comparative mapping of Quantitative trait loci (QTLs) involved in domestication of adaptative syndrome traits of pearl millet was realized at the intra-specific level using two F(2) populations derived from domesticated ( Pennisetum glaucum ssp. glaucum) x wild ( Pennisetum glaucum ssp. monodii) crosses. The two domesticated parents analyzed differ in their geographical origins, agronomic characteristics and life cycles. In both populations, two regions of the genome were identified on linkage groups 6 and 7, that controlled most of the key morphological differences. The importance of these two linkage groups reveals their central role both in the developmental control of spikelet structure and in the domestication process of this crop. In contrast, QTLs involved in traits that are components of yield and measure differences in resource allocation (such as the shape of the spike, the number of spikes per plant and plant height) show a low level of correspondence among our two crosses. The results of the comparative mapping between cereals, although preliminary, reveal that genes involved in seed-shattering could correspond in maize, rice and sorghum. The evolutionary significance of our results, and especially the relationships between genome organization and cereal domestication, are discussed. The potential use of these results in pearl millet genetic-resources enhancement are presented.

Phosphatidylinositol 3-kinase, protein kinase B and ribosomal S6 kinases in the stimulation of thyroid epithelial cell proliferation by cAMP and growth factors in the presence of insulin

The proliferation of most normal cells depends on the co-operation of several growth factors and hormones, each with a specific role, but the key events involved in the action of each necessary stimulant remain largely uncharacterized. In the present study, the pathways involved in the mechanism(s) of co-operation have been investigated in primary cultures of dog thyroid epithelial cells. In this physiologically relevant system, thyroid stimulating hormone (TSH) acting through cAMP, epidermal growth factor (EGF) and phorbol esters (such as PMA) induce DNA synthesis. Their effect requires stimulation of the insulin-like growth factor-1 (IGF-1) receptor by either IGF-1 or insulin, which are not themselves mitogenic agents. In contrast, hepatocyte growth factor (HGF) is itself fully mitogenic. The results of the study demonstrate that cAMP, EGF, HGF and PMA stimulate p70 ribosomal S6 kinase (p70 S6 kinase). However, insulin/IGF-1 also stimulate p70 S6 kinase. Thus stimulation of p70 S6 kinase might be necessary, but is certainly not sufficient, for the induction of DNA synthesis and is not specific for any stimulated pathway. In contrast, phosphatidylinositol 3-kinase (PI 3-kinase) and protein kinase B (PKB) activation by insulin and HGF is strong and sustained, whereas it is weak and transient with EGF and absent in the presence of TSH or PMA. These findings suggest that: (i) stimulation of PI 3-kinases and/or PKB is not involved in the cAMP-dependent pathways leading to thyrocyte proliferation, or in the action of PMA, (ii) the stimulation of the PI 3-kinase/PKB pathway may account for the permissive action of insulin/IGF-1 in the proliferation of these cells, and (iii) the stimulation of this pathway by HGF may explain why this agent does not require insulin or IGF-1 for its mitogenic action.

Phosphorylation of the three Rb protein family members is a common step of the cAMP-, the growth factor, and the phorbol ester-mitogenic cascades but is not necessary for the hypertrophy induced by insulin

Thyrotropin (TSH) through the cAMP cascade and in the presence of insulin induces the proliferation of dog thyroid cells. In this work, it is shown that TSH via cAMP causes the phosphorylation of the three members of the pRb family, pRb, p107, and p130, with the same kinetics as those observed when these cells are stimulated by mitogens acting through a tyrosine kinase receptor or through activation of kinase C. It is the first described point of convergence of cAMP-dependent and -independent mitogenic pathways in dog thyrocytes and suggests that the phosphorylation of the three proteins may be involved in the initiation of DNA synthesis in these cells. We also show that insulin, which induces hypertrophy and is permissive for the TSH mitogenic action, does not provoke the phosphorylation of any pRb family member, suggesting that none of these phosphorylations is required for this effect.

Thyrotropin via cyclic AMP induces insulin receptor expression and insulin Co-stimulation of growth and amplifies insulin and insulin-like growth factor signaling pathways in dog thyroid epithelial cells

Despite the similarity of their receptors and signal transduction pathways, insulin is regarded as a regulator of glucose, protein, and lipid metabolism, whereas insulin-like growth factors (IGF-I and IGF-II) mainly act as mitogenic hormones. In the dog thyroid primary culture model, the triggering of DNA synthesis by thyrotropin (TSH) through cAMP, or by cAMP-independent factors including epidermal growth factor, hepatocyte growth factor and phorbol esters, requires insulin or IGFs as comitogenic factors. In the present study, in TSH-treated cells, IGF-I receptors and insulin receptors were paradoxically equivalent in their capacity to elicit the comitogenic pathway, which, however, was mediated only by IGF-I receptors in dog thyroid cells stimulated by cAMP-independent mitogens. Moreover, prior cell exposure to TSH or forskolin increased their responsiveness to insulin, IGF-I, and IGF-II, as seen on DNA synthesis and activation of a common insulin/IGF signaling pathway. To understand these observations, binding characteristics and expression of insulin and IGF-I receptors were examined. To analyze IGF-I receptor characteristics, the unexpected interference of a huge presence of IGF-binding proteins at the cell membrane was avoided using labeled Long R3 IGF-I instead of IGF-I. Strikingly, TSH, through cAMP, time-dependently induced insulin binding and insulin receptor mRNA and protein accumulation without any effect on IGF-I receptors. These findings constitute a first example of an induction of insulin receptor gene expression by a cAMP-mediated hormone. In dog thyroid cells, this allows low physiological insulin concentrations to act as a comitogenic factor and might explain in part the enhanced responsiveness to IGFs in response to TSH. This raises the possibility that TSH-insulin interactions may play a role in the regulation of thyroid growth and function in vivo.

c-Myc expression is controlled by the mitogenic cAMP-cascade in thyrocytes

In dog thyroid epithelial cells in primary culture, thyrotropin (TSH), acting through cAMP, induces proliferation and differentiation expression, whereas epidermal growth factor (EGF) and phorbol esters induce proliferation and dedifferentiation. In these cells, we have detailed the regulation by cAMP of the c-myc protooncogene mRNA and protein. The cAMP signaling pathway induces a biphasic increase of c-myc mRNA and protein. c-Myc protein accumulation follows the abundance and kinetics of its mRNA expression. Using in vitro elongation of nascent transcripts to measure transcription and actinomycin D (AcD) chase experiments to study mRNA stability, we have shown that in the first phase cAMP releases a transcriptional elongation block. No modification of transcriptional initiation was observed. After 30 min of treatment with TSH, c-myc mRNA was also stabilized. During the second phase, cAMP stabilization of the mRNA disappears and transcription is again shut off. Thus, in a tissue in which it stimulates proliferation and specific gene expression, cAMP regulates biphasically c-myc expression by mechanisms operating at the transcriptional and posttranscriptional levels.

Expression and subcellular localization of CDK2 and cdc2 kinases and their common partner cyclin A in thyroid epithelial cells: comparison of cyclic AMP-dependent and -independent cell cycles

Dog thyroid epithelial cells in primary culture constitute a model of positive control of DNA synthesis initiation and G0-S prereplicative phase progression by cyclic AMP as a second messenger for TSH. In tis early steps, this mitogenic control is quite distinct from cyclic AMP-independent mitogenic cascades elicited by growth factors. We demonstrate here that TSH (cyclic AMP) and EGF+serum (cyclic AMP-independent) stimulations cooperate and finally converge on proteins that control the cell cycle machinery. This convergence included a common induction of the expression of cyclin A and p34cdc2, and to a lesser extent of p33/38cdk2, which was already expressed in quiescent thyroid cells, and common changes of cdc2 and CDK2 phosphorylations as evidenced by electrophoretic mobility shifts. Kinetic differences in these processes after stimulation by TSH or EGF+serum or by these factors in combination correlated with differences in cell cycle kinetics. Moreover, an immunofluorescence analysis of these proteins using the double labeling of PCNA as a marker of each cell cycle phase shows: (1) a previously undescribed nuclear translocation of CDK2 before S phase initiation; (2) a sudden increase of cdc2 nuclear immunoreactivity at G2/mitosis transition. These data support the roles of CDK2 and cdc2 at G1/S and G2/mitosis transitions, respectively. (3) We were unable to demonstrate in individual cells a strict association between the nuclear appearance of cyclin A and G1/S transition, and an association of cyclin A and CDK2 with PCNA-stained DNA replication sites. On the other hand, the lengthening of G2 phase in the TSH/cyclic AMP-dependent thyroid cell cycle was associated with a stabilization of Tyr15 inhibitory phosphorylation of cdc2 and an especially high nuclear concentration of cyclin A and CDK2. We hypothesize that high nuclear accumulation of cyclin A and CDK2 during G2 phase could be causative in the cyclic AMP-dependent delay of mitosis onset.

Herpesvirus-like DNA sequences in patients with Mediterranean Kaposi's sarcoma

DNA sequences closely related to herpesvirus-like sequences have been found in AIDS-associated Kaposi's sarcoma. Using PCR, we found herpesvirus-like DNA sequences in Kaposi's lesions and normal adjacent skin in five patients with Mediterranean Kaposi's sarcoma. We did not find these sequences in tissues from patients without Kaposi's sarcoma. Semi-quantitative PCR revealed many more herpesvirus-like sequences in Kaposi's lesions than in unaffected skin. Our results reinforce the hypothesis that an infectious agent closely related to gamma-herpesvirus is implicated in the pathogenesis of Mediterranean and AIDS-associated Kaposi's sarcoma.

Rapid purification and identification of calcyphosine, a Ca(2+)-binding protein phosphorylated by protein kinase A

A method is presented for the rapid purification of dog thyroid calcyphosine, a protein previously identified as a major substrate for cyclic AMP-dependent protein kinase in dog thyroid slices stimulated by thyrotropin [Lecocq, Lamy and Dumont (1979) Eur. J. Biochem. 102, 147-152]. The protein was previously identified as a spot on two-dimensional gels and is now purified in its native form by a procedure involving three chromatographic steps. Homogeneous calcyphosine identified by SDS/PAGE, immunoblotting and peptide sequencing can be obtained within 7 h. As for calmodulin, Ca(2+)-dependent conformational changes can be shown by Ca(2+)-dependent hydrophobic interaction chromatography using phenyl-Sepharose. Unlike calmodulin, calcyphosine is a substrate for protein kinase A.

Immunocyte enumeration in duodenal biopsies of migraine without aura patients with or without food-induced migraine

The possibility of an IgE-mediated allergic mechanism in food-induced migraine remains controversial. Twenty consecutive migraine patients, 11 with food-induced migraine, 9 without, were investigated for determination and counting of immunocyte populations (IgA, IgM, IgE, IgG containing cells) by biopsies at duodenum 2 level. Conventional histology and plasmocyte populations were not significantly different between the two groups of migraine patients. This study does not support the existence of an IgE-mediated allergic mechanism in food-induced migraine.

Characterization and identification as cofilin and destrin of two thyrotropin- and phorbol ester-regulated phosphoproteins in thyroid cells

Using separation of total cellular proteins by two dimensional (2-D) gel electrophoresis (isoelectric focusing/SDS-PAGE) we have characterized two regulated proteins, p21 and p19, in dog thyroid cells. We have used the same 2-D gel technique to purify these proteins before their trypsin cleavage and partial sequencing. Three peptides were sequenced in the case of p19 and two peptides in the case of p21. The Swiss-Prot protein sequence database revealed that p19 was identical to destrin/ADF (actin depolymerizing factor) and p21 to cofilin, two closely related and widely distributed actin-binding proteins. This was further verified by cross-reactivity with specific antibodies against brain cofilin and chicken ADF. We have demonstrated, using 2-D gel electrophoresis with a nonequilibrium pH gradient in the first dimension (nonequilibrium pH gradient in the first dimension (nonequilibrium pH gradient electrophoresis/SDS-PAGE) that, in the thyroid cell, cofilin and destrin/ADF were present, under control conditions, in two forms: a phosphorylated and an unphosphorylated one. Thyrotropin (TSH), through cyclic AMP, provoked a very rapid dephosphorylation of these two proteins, which was already maximal after 20 min of action, whereas their dephosphorylation in response to 12-O-tetradecanoylphorbol-13-acetate (TPA) was slower. This suggests that dephosphorylation of cofilin and destrin/ADF by TSH could be implicated in the disruption of actin-containing stress fibers and in the reorganization of microfilaments induced by this hormone. Epidermal growth factor, which does not induce acute morphological changes in thyroid cells, did not affect the state of phosphorylation of cofilin and destrin/ADF except for a delayed decrease (after 24 h) of destrin/ADF phosphorylation. A 10% dimethyl sulfoxide treatment of thyroid cells also induced rapid dephosphorylation of destrin and cofilin. This was accompanied by a reorganization of actin microfilaments that clearly resembles the one induced by TSH and by the appearance of intranuclear cofilin-containing rods. However, these rod structures were not observed in response to TSH, forskolin, or TPA, suggesting that dephosphorylation of cofilin correlates with the reorganization of actin microfilaments but not with the nuclear transport of cofilin. We propose that the dephosphorylation of destrin and cofilin could be involved in the TSH-stimulated macropinocytic activity, a key process in thyroid hormone secretion.

[Gastroduodenal tolerance of methylprednisolone. Study of oral versus intravenous administration in healthy volunteers]

OBJECTIVES

To endoscopically evaluate the tolerance of gastroduodenal mucosa to methylprednisolone given orally and intravenously.

METHODS

Thirty two healthy volunteers (age range 18-39 years) were divided randomly into two groups of 16 each (8 males and 8 females). All were Caucasians, gave their informed consent and were considered normal after a complete clinical and laboratory work-up including gastroduodenal fibroscopy. Methylprednisolone (500 mg) was administered for three consecutive days at 9 a.m., orally in one group and intravenously in the second group. No other drugs were being taken and alcohol and smoking were prohibited from day 0 to day 11. Tolerance was evaluated on days 4 and 11 based on clinical examination, blood pressure, heart rate, oral temperature, body weight, blood and urine chemistry and by video-recorded gastroduodenal endoscopy. Two independent endoscopists, uninformed of the patient's regimen, scored lesions from 0 (normal) to 5 (more than 25 lesions including at least 2 erosions). In case of abnormal findings, follow-up was continued to normalization.

RESULTS

Endoscopically detectable lesions (stage I) attributed to corticosteroid therapy were observed in 4 subjects in the oral group and in 5 in the intravenous group. All regressed spontaneously. Duodenal lesions were observed only after oral administration while lesions of gastric mucosa were mostly found after intravenous administration. Systemic effects included abdominal pain after oral intake, 1 case of insomnia and bitter taste in the mouth after intravenous administration.

CONCLUSIONS

These findings suggest that the effect of corticosteroid therapy, on the gastric mucosa, is basically systemic, and on the duodenal mucosa, basically local. No severe manifestations were observed after high-dose methylprednisolone given orally or by intravenous injection.

Cloning of cDNA specifically involved in the thyroid cAMP mitogenic pathway

The activation of the cyclic AMP cascade in dog and human thyroid cells in primary culture induces the expression of differentiated gene expression, hyperfunction and proliferation. These programs are developed simultaneously in quiescent dedifferentiated cells. In this paper the strategy followed by our group to define the genes involved in the cAMP mitogenic cascade is outlined.

General inhibition by transforming growth factor beta 1 of thyrotropin and cAMP responses in human thyroid cells in primary culture

Transforming growth factor beta 1 (TGF beta 1) mRNA has previously been identified in human thyroid cells and this agent has been shown to inhibit DNA synthesis in thyroid cells of some other species. In normal human thyroid cells in primary culture, TGF beta 1 inhibited inconstantly the low basal DNA synthesis and strongly the stimulation of DNA synthesis by epidermal growth factor (EGF) and serum, and by thyroid-stimulating hormone (TSH) acting through cAMP. This inhibition, by TGF beta 1, of the TSH and cAMP-dependent DNA synthesis was associated with an inhibition of PCNA (proliferating cell nuclear antigen) synthesis. TGF beta 1 almost completely abolished the cAMP induced stimulation of iodide uptake and thyroperoxidase synthesis. It thus, like EGF, also acts as a dedifferentiating agent. Investigation of the pattern of protein synthesis by two-dimensional gel electrophoresis revealed that while TGF beta 1, by itself, increased the synthesis of only one protein, a tropomyosin isoform, it inhibited most of the effects of cAMP on protein synthesis (35 out of 45 cAMP-regulated proteins were affected). It also reversed the effect of cAMP on the morphology of the thyrocytes. The fact that TGF beta 1 did not affect the increase in cAMP provoked by TSH in human thyroid cells while inhibiting most of the effects of dibutyryl cAMP in these cells suggests an action at a step distal to cAMP generation.(ABSTRACT TRUNCATED AT 250 WORDS)

Phosphorylation of mitogen-activated protein kinases is involved in the epidermal growth factor and phorbol ester, but not in the thyrotropin/cAMP, thyroid mitogenic pathway

In dog thyroid epithelial cells (thyrocytes) in primary culture, thyrotropin (TSH) acting through cAMP induces proliferation and differentiation expression, whereas epidermal growth factor (EGF) and tumor-promoting phorbol esters induce proliferation and dedifferentiation. In these cells we have demonstrated mitogen-activated protein (MAP) kinase phosphorylation by 32P labeling and two-dimensional gel electrophoresis and by immunodetection with anti-MAP kinase and anti-phosphotyrosine antibodies after one- or two-dimensional gel electrophoresis. MAP kinase localization was demonstrated by immunochemical staining. We show the following results. (i) As in other systems, EGF and phorbol esters induced p42 and p44 MAP kinases phosphorylation on tyrosine, serine, and threonine. This effect was rapid, peaking after 5 and 15 min, respectively, followed by a slow decline thereafter. It preceded a translocation of MAP kinase immunoreactivity from cytoplasm to nucleus. (ii) Carbamylcholine, a potent stimulator of the Ca(2+)-phosphatidylinositol cascade which is unable to induce DNA synthesis, stimulated MAP kinases phosphorylation and nuclear staining with kinetics similar to those observed after EGF action, indicating that MAP kinase phosphorylation was not sufficient for mitogenesis. (iii) The cAMP-dependent mitogenic cascade elicited by TSH and forskolin did not involve the phosphorylation and nuclear translocation of p42 and p44 MAP kinases at any time during the entire prereplicative phase. Activation of MAP kinases by phosphorylation is therefore not a necessary step in the G0-G1 transition in this mitogenic cascade.

Selenium and the thyroid: how the relationship was established

Several hypotheses concerning consequences of selenium deficiency on iodine metabolism can be proposed on the basis of experimental studies in rats and from epidemiological and experimental studies in humans. By decreasing intracellular GSH peroxidase activity, selenium deficiency may increase hydrogen peroxide (H2O2) supply and lead over several weeks to the thyroid atrophy observed in myxoedematous cretins. By improving thyroid hormone synthesis and by decreasing peripheral thyroxin (T4) deiodination, selenium deficiency could protect fetal brain T4 supply and thus prevent neurologic cretinism. Selenium deficiency may protect against iodine deficiency by decreasing T4 metabolism--and thus iodide leakage and--perhaps also by increasing H2O2 supply and thyroid hormone synthesis and thus thyroid efficiency.