Social acceptability of psilocybin-assisted therapy for existential distress at the end of life: A population-based survey

BACKGROUND

Internationally, there is a growing interest in the potential benefits of psilocybin-assisted therapy to treat existential distress at the end of life. However, the social acceptability of this therapy is not yet well known.

AIM

This study assesses the social acceptability of the medical use of psilocybin to treat existential distress at the end of life.

DESIGN

An online survey was conducted in Canada between November 23 and December 4, 2022. The questionnaire included items pertaining to perceptions, attitudes and concerns towards psilocybin-assisted therapy to treat existential distress at the end of life.

PARTICIPANTS

The sample (n = 2800) was stratified by province, age and sex. Participants were adults from four provinces of Canada: Québec, Ontario, Alberta and British Columbia.

RESULTS

Overall, 79.3% considered psilocybin-assisted therapy a reasonable medical choice for a patient suffering from existential distress at the end of life, 84.8% agreed that the public health system should cover the costs of the intervention and 63.3% would welcome the legalisation of psilocybin for medical purposes. Previous psilocybin use (p < 0.0001, for all dependent variables), exposure to palliative care (p < 0.05, for all dependent variables) and a progressive political orientation (p < 0.05, for all dependent variables) were associated with more favourable attitudes towards psilocybin-assisted therapy at the end of life.

CONCLUSION

The social acceptability of psilocybin-assisted therapy for existential distress at the end of life is rather high in Canada. These findings may contribute to efforts to mobilise resources and improve access to this emerging therapy in palliative and end of life care settings.

Joint Forces for Child and Adolescent Psychiatry Training: 1st ESCAP/UEMS-CAP/EFPT Training Day for CAP Trainees

Introduction

As the Covid-19 pandemic brought about travel and social restrictions, many activities including specialty training events for medical specialty trainees moved online. The European Federation of Psychiatric Trainees, European Society for Child and Adolescent Psychiatry and hild and Adolescent Psychiatry (CAP) Section of UEMS joined forces to turn challenges into an opportunity for CAP trainees and jointly organized the 1st ESCAP/UEMS-CAP/EFPT Training Day.

Objectives

The main aim was to offer CAP trainees throughout Europe high quality and up to date training content free of charge, making use of the different strengths of the organizing associations.

Methods

Content of the Training Day was prepared according to feedback and demand from CAP trainees, collected through a questionnaire prior to the event. This event took place online and ran 9 webinars/workshops as well as a plenary case session where trainees presented real life cases made more challenging with the pandemic and representatives from 3 organizing associations discussed the cases from different perspectives. Remaining webinars/workshops covered a wide range of themes including but not limited to research, leadership, administrative and management skills as well as scientific topics such as eating disorders, medically unexplained symptoms, psychosis.

Results

Almost 200 CAP trainees from 31 countries participated in the event and received certificates of completion. The outcome of the event is being evaluated via quantitative and qualitative methods and similar events will be planned accordingly.

Conclusions

1st ESCAP/UEMS-CAP/EFPT Training Day for CAP trainees was a success for reaching many trainees from across Europe and experimenting with different formats which will inspire future initiatives.

Disclosure

No significant relationships.

A predominantly tropical influence on late Holocene hydroclimate variation in the hyperarid central Sahara

The climate history of the Sahara desert during recent millennia is obscured by the near absence of natural climate archives, hampering insight in the relative importance of southerly (tropical) and northerly (midlatitude) weather systems at submillennial time scales. A new lake sediment record from Ounianga Serir oasis in northern Chad, spanning the Late Holocene without interruption, confirms that immediately before ca 4200 years ago, the Sahara experienced an episode of hyperaridity even more extreme than today's desert climate. The hypersaline terminal lake which formed afterwards never desiccated during the late Holocene due to continuous inflow of fossil groundwater, yet its water balance was sensitive to temporal variation in local rainfall and lake surface evaporation. Our in-lake geochemical proxies show that, during the last 3000 years, century-scale hydroclimate variation in the central Sahara primarily tracked the intensity of the tropical West African monsoon, modulated at shorter time scales by weather patterns linked to shifts in midlatitude Atlantic Ocean circulation.

Persistent organic pollutants in sediments of the Wouri Estuary Mangrove, Cameroon: Levels, patterns and ecotoxicological significance

The anthropogenic impact in the Wouri Estuary Mangrove located in the rapidly developing urban area of Douala, Cameroon, Africa, was studied. A set of 45 Persistent Organic Pollutant were analysed in surficial mangrove sediments at 21 stations. Chlorinated Pesticides (CLPs), Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) have concentrations ranging from 2.2 - 27.4, and 83 - 544 ng/g, respectively. The most abundant CLPs were endosulfan, alachlor, heptachlor, lindane (γ-HCH) and DDT, which metabolites pattern revealed recent use. Selected PAHs diagnostic ratios show pyrolytic input predominantly. The sum of 7 carcinogenic PAHs (ΣC-PAHs) represented 30 to 50% of Total PAHs (TPAHs). According to effect-based sediment quality guidelines, the studied POPs levels imply low to moderate predictive biological toxicity. This study contributes to depict how far water resources are shifting within what is now termed the Anthropocene due to increasing local pressures in developing countries or African countries.

Water transit time and active recharge in the Sahel inferred by bomb-produced 36Cl

The lack of data and suitable methods to quantify regional hydrological processes often hinders sustainable water management and adaptation to climate change in semiarid regions, particularly in the Sahel, which is known for its climatic variability. Here we show that ³⁶Cl from nuclear tests is a promising method to estimate water transit times and groundwater recharge rates on the catchment scale, and to distinguish water and chloride cycles. ³⁶Cl was measured in 131 surface and groundwater samples in the Chari-Logone sub-catchment of the emblematic Lake Chad Basin, located in central Sahel. It was found that only 12 ± 8% of the catchment is connected to the main rivers. Groundwater supporting rivers in the upper humid part of the catchment has a mean transit time of 9.5 ± 1 years and a recharge rate of 240 ± 170 mm yr⁻¹. In the lower Sahelian part of the catchment, stream-focused recharge yields recharge rates up to 78 ± 7 mm yr⁻¹ in riparian groundwater against 16 ± 27 mm yr⁻¹ elsewhere. Our estimates suggest that aquifers in the Sahel host a significant amount of renewable water, which could therefore be used as a strategic freshwater resource.

Lead, zinc, and copper redistributions in soils along a deposition gradient from emissions of a Pb-Ag smelter decommissioned 100 years ago

Sourcing and understanding the fate of anthropogenic metals in a historical contamination context is challenging. Here we combined elemental and isotopic (Pb, Zn, Cu) analyses with X-ray Absorption Spectroscopy (XAS) measurements (Zn) to trace the fate, in undisturbed soil profiles, of historical metal contamination emitted by a 167-year-old Pb-Ag smelter decommissioned 100 years ago located in the Calanques National Park (Marseilles, France). Lead isotopic measurements show that entire soil profiles were affected by 74 years of Pb emissions up to ~7 km from the smelter under the main NNW wind, and indicate particulate transfer down to 0.8 m at depth. This vertical mobility of anthropogenic Pb contrasts with previous studies where Pb was immobilized in surface horizons. The contribution of anthropogenic Pb to the total Pb concentration in soil was estimated at 95% in surface horizons, and 78% in the deepest horizons. Zinc isotopic signatures of past emissions that are enriched in light isotopes compared to the natural geological background (-0.70 ± 0.04‰ and -0.15 ± 0.02‰, respectively), were detected only in the surface horizons of the studied soils. Using XAS analyses, we showed that anthropogenic Zn was transformed and immobilized in surface horizons as Zn-Layered Double Hydroxide, thus favoring the enrichment in heavy isotopes in these surface horizons. No clear evidence of copper contamination by the smelter was found and Cu isotopes point to a bedrock origin and a natural distribution of Cu concentrations.

Early anthropogenic impact on Western Central African rainforests 2,600 y ago

A potential human footprint on Western Central African rainforests before the Common Era has become the focus of an ongoing controversy. Between 3,000 y ago and 2,000 y ago, regional pollen sequences indicate a replacement of mature rainforests by a forest-savannah mosaic including pioneer trees. Although some studies suggested an anthropogenic influence on this forest fragmentation, current interpretations based on pollen data attribute the ''rainforest crisis'' to climate change toward a drier, more seasonal climate. A rigorous test of this hypothesis, however, requires climate proxies independent of vegetation changes. Here we resolve this controversy through a continuous 10,500-y record of both vegetation and hydrological changes from Lake Barombi in Southwest Cameroon based on changes in carbon and hydrogen isotope compositions of plant waxes. [Formula: see text]13C-inferred vegetation changes confirm a prominent and abrupt appearance of C4 plants in the Lake Barombi catchment, at 2,600 calendar years before AD 1950 (cal y BP), followed by an equally sudden return to rainforest vegetation at 2,020 cal y BP. [Formula: see text]D values from the same plant wax compounds, however, show no simultaneous hydrological change. Based on the combination of these data with a comprehensive regional archaeological database we provide evidence that humans triggered the rainforest fragmentation 2,600 y ago. Our findings suggest that technological developments, including agricultural practices and iron metallurgy, possibly related to the large-scale Bantu expansion, significantly impacted the ecosystems before the Common Era.

Crystal structure of the active form of native human thymidylate synthase in the absence of bound substrates

Human thymidylate synthase (hTS) provides the sole de novo intracellular source of thymidine 5'-monophosphate (dTMP). hTS is required for DNA replication prior to cell division, making it an attractive target for anticancer chemotherapy and drug discovery. hTS binds 2'-deoxyuridine 5'-monophosphate (dUMP) and the folate co-substrate N⁵,N¹⁰-methylenetetrahydrofolate (meTHF) in a pocket near the catalytic residue Cys195. The catalytic loop, which is composed of amino-acid residues 181-197, can adopt two distinct conformations related by a 180° rotation. In the active conformation Cys195 is close to the active site, while in the inactive conformation it is rotated and Cys195 is too distant from the active site for catalysis. Several hTS structures, either native or engineered, have been solved in the active conformation in complex with ligands or inhibitors and at different salt concentrations. However, apo hTS structures have been solved in an inactive conformation in high-salt and low-salt conditions (PDB entries 1ypv, 4h1i, 4gyh, 3egy and 3ehi). Here, the structure of apo hTS crystallized in the active form with sulfate ions coordinated by the arginine residue that binds dUMP is reported.

Ice-sheet collapse and sea-level rise at the Bølling warming 14,600 years ago

Past sea-level records provide invaluable information about the response of ice sheets to climate forcing. Some such records suggest that the last deglaciation was punctuated by a dramatic period of sea-level rise, of about 20 metres, in less than 500 years. Controversy about the amplitude and timing of this meltwater pulse (MWP-1A) has, however, led to uncertainty about the source of the melt water and its temporal and causal relationships with the abrupt climate changes of the deglaciation. Here we show that MWP-1A started no earlier than 14,650 years ago and ended before 14,310 years ago, making it coeval with the Bølling warming. Our results, based on corals drilled offshore from Tahiti during Integrated Ocean Drilling Project Expedition 310, reveal that the increase in sea level at Tahiti was between 12 and 22 metres, with a most probable value between 14 and 18 metres, establishing a significant meltwater contribution from the Southern Hemisphere. This implies that the rate of eustatic sea-level rise exceeded 40 millimetres per year during MWP-1A.

Penultimate deglacial sea-level timing from uranium/thorium dating of Tahitian corals

The timing of sea-level change provides important constraints on the mechanisms driving Earth's climate between glacial and interglacial states. Fossil corals constrain the timing of past sea level by their suitability for dating and their growth position close to sea level. The coral-derived age for the last deglaciation is consistent with climate change forced by Northern Hemisphere summer insolation (NHI), but the timing of the penultimate deglaciation is more controversial. We found, by means of uranium/thorium dating of fossil corals, that sea level during the penultimate deglaciation had risen to ~85 meters below the present sea level by 137,000 years ago, and that it fluctuated on a millennial time scale during deglaciation. This indicates that the penultimate deglaciation occurred earlier with respect to NHI than the last deglacial, beginning when NHI was at a minimum.

Atmospheric lead fallout over the last century recorded in Gulf of Lions sediments (Mediterranean Sea)

Six marine sediment cores from the Gulf of Lions continental slope (700-1700 m water depth) were analyzed for stable lead isotopes and (210)Pb geochronology in order to reconstruct lead atmospheric fallout pattern during the last century. The detrital lead contribution is 25 microg g(-1) and the mean sediment anthropogenic inventory is 110+/-7 microg cm(-2), a little bit higher than atmospheric deposition estimate. Anthropogenic lead accumulation in sediments peaked in early 1970s (1973+/-2) in agreement with lead emissions features. For the period 1986-1997, the sediment signal also reflect the decrease of atmospheric lead described by independent atmospheric fallout investigations. The anthropogenic Pb deposition in the late 1990s was similar to the 1950s deposition, attesting thus of the output of European environmental policies.

[BNP and dyspnea: proposition of a diagnostic strategy based on two cut-off]

The purpose of this study was to evaluate the cut-off value of brain natriuretic peptide (BNP) assayed with AxSYM BNP assay (Abbott). 86 patients have been included (mean age of 66 years). The clinical sensibility was 100% at 100 ng/L versus 80% at 250 ng/L. The clinical specificity was 66% at 100 ng/L versus 92% at 250 ng/L. The positive predictive value was 80% at 100 ng/L versus 92% at 250 ng/L. The negative predictive value was 100% at 100 ng/L versus 88% at 250 ng/L. The double cut-off strategy is more suitable to diagnose a dyspnea of cardiac origin than the usual strategy based on a single cut-off.value. With such a strategy, the two cut-off strategy improve the diagnosis of 9% in the total population.

[Proposal for a discriminant level of BNP in very elderly persons with heart failure]

A diagnosis of heart failure (HF) in elderly patient can be difficult. The purpose of this study is to evaluate the cut-off of brain natriuretic peptide (BNP) Triage Assay (Biosite) in the diagnosis of HF in this population : 250 very older patients with age <or= 75 years (mean 82.7 years) were included in this study; 180 patients were diagnosed with HF based on clinical and echocardiographic findings. The sensibility is of 95% at 100 ng/L versus 83% at 300 ng/L. The specificity is of 21% versus 50% at 300 ng/L. The positive predictive value is of 17% at 100 ng/L versus 23% at 300 ng/L. The negative predictive value is of 96% at 100 ng/L versus 95% at 300 pg/L. The cut-off set at 300 ng/L is more suitable as HF marker in the very old population.

[Utility of BNP measurement in the emergency room in patients with suspected unstable angina with a normal ECG]

Unstable angina is a serious condition, difficult to diagnose in the emergency room. Clinical, electrocardiographic and biological signs (increased troponine) are not sensitive. The authors set out to assess whether measuring B natiuretic peptide in the emergency room was more sensitive for identifying symptomatic coronary lesions. One hundred and twenty patients admitted to the emergency room for chest pain compatible with the diagnosis of unstable angina and a normal ECG were included in this prospective study. All patients underwent coronary angiography during their hospital admission. The sensitivities of troponine at a threshold of 0.4 ng/ml and of brain natiuretic peptide (BNP) at a threshold of 10 pg/ml in this population were 66% and 92% respectively. The use of troponine and BNP together provided better results than troponine and BNP alone for the identification of patients with chest pain with significant coronary lesions.

[Value of type B natriuretic peptide in the emergency management of patients with suspected cardiac failure. Report of 125 cases]

Shortness of breath is a common cause of consultation in the emergency unit. Therefore, it is essential to diagnose cases of cardiac failure. This may be difficult in some cases. The authors set out to assess the value of measuring brain natiuretic peptide in this context. Brain natiuretic peptide (BNP) was measured by an ultrafast method (Biosite/BMD) on arrival of 125 patients to the emergency unit. The results were then compared with the diagnoses made in the emergency unit and those of the hospital discharge summary. Nearly 18% of patients were wrongly classified in the emergency room; 1/3 were falsely diagnosed as cardiac failure and 2/3 were not recognised initially as having cardiac failure. In 90% of patients, in particular in the group wrongly considered as not having cardiac failure, BNP measurement could have helped correct the mistake. The optimal threshold value of BNP for diagnosis of cardiac failure in this study was 300 pg/mL, with positive and negative predictive values of 92.4 and 90.2%, respectively.

XAS applied to pharmaceuticals: drug administration and bioavailability

We present selected XAS applications, focused towards practical hospital questions of drug administration and bioavailability, where the technique is driven up to its limits of sensitivity. i) XAS was used to study the interactions between the components of parenteral nutrition solutions, in particular zinc and aminoacids, possibly modifying their bioavailability. ii) We studied by EXAFS a series of binary and ternary copper-aminoacid complexes, in view of the development of an efficient oral drug against copper deficiencies in Menkes disease. iii) EXAFS and XANES analysis allowed us to characterise the solution form of a new arsenic containing drug against leukaemia. In parallel to the XAS measurements, we analysed trace elements levels along patients' hairs, using X-ray fluorescence excited by synchrotron radiation. The measurements along the hair allow for a monitoring of essential trace elements during therapy.

Stimulation of osteoclast differentiation in vitro by mouse oncostatin M, leukaemia inhibitory factor, cardiotrophin-1 and interleukin 6: synergy with dexamethasone

The role of oncostatin M in bone metabolism is not clearly defined, and the actions of mouse oncostatin M (mOSM) on osteoclast development has not been previously determined. We therefore examined the ability of recombinant mOSM to stimulate osteoclast formation and activity using cocultures of murine calvaria and bone marrow cells, and compared the responses to other members of the interleukin 6 family of cytokines including mouse leukaemia inhibitory factor (LIF), cardiotrophin-1 (CT-1) and IL-6. Mouse OSM, LIF and CT-1 strongly induced the formation of tartrate resistant acid phosphatase positive (TRAP(+)) multinucleated cells (MNC) in a dose-dependent fashion. OSM, LIF or CT-1 also elevated the number and size of resorptive pits when cocultures were added to smooth cortical bone slices, indicating enhancement of osteoclast activity. The activity of OSM was reduced by indomethacin (10(-8)-10(-6) M), whereas addition of dexamethasone (DEX) at 10(-7)-10(-5) M synergistically enhanced OSM-induced numbers of TRAP(+)MNC. DEX (10(-7) M) costimulation also synergistically enhanced TRAP(+)cell numbers of LIF, and CT-1 treated cocultures. IL-6 had no activity alone, but further enhanced TRAP(+)cell formation in mOSM or DEX (10(-7) M) treated cocultures. When added to mouse calvarial osteoblast cultures, mOSM induced secretion of IL-6 protein and elevation of mRNA whereas LIF or CT-1 did not. IL-6 mRNA levels and protein secretion were reduced in osteoblasts by costimulation with DEX. These results show that mouse OSM, LIF and CT-1 induce osteoclast differentiation and activation, that DEX synergizes with each in this activity, and that mouse OSM induces responses in osteoblasts that are not shown by LIF or CT-1. Collectively these data suggest an important role of these cytokines in osteoporosis caused by high levels of corticosteroid.

Submicrometre beams from a hard X-ray waveguide at a third-generation synchrotron radiation source

The use of an X-ray waveguide for scattering experiments at an undulator of a third-generation synchrotron radiation source is discussed. The performance with a perfect crystal monochromator, multilayer monochromator and focusing mirror is explored. A maximum flux of 8 x 109 photons s(-1) at lambda = 0.083 nm was obtained for a 0.15 (V) x 600 (H) micron(2) beam at the exit of the waveguide with a multilayer monochromator. The combination of an Si (111) monochromator and ellipsoidal mirror resulted in a flux of approximately 10(9) photons s(-1) but with a horizontal compression of the beam to approximately 30 micron. The use of the waveguide in diffraction experiments is addressed.

[Physiopathology of bedsores]

Pressure is the primary pathogenic factor in the development of decubitus ulcers. Other major factors are shearing forces, friction and moisture. Significant intrinsic risk factors are immobility, age-related diseases, nutritional status, medications and smoking. The morbidity and mortality related to the complications of pressure sores are quite significant. Prevention is essential and is best achieved by identification of high risk patients. The therapeutic approach is based on the grade of pressure ulcer.

Histomorphometric analysis of the effects of standard heparin on trabecular bone in vivo

Long-term heparin treatment causes osteoporosis through an as yet undefined mechanism. To investigate this phenomenon, we treated rats with once daily subcutaneous injections of heparin (in doses ranging from 0.25 to 1.0 U/g) or saline for 8 to 32 days and monitored the effects on bone both histomorphometrically and by serial measurements of urinary type 1 collagen cross linked-pyridinoline (PYD) and serum alkaline phosphatase, markers of bone resorption and formation, respectively. Histomorphometric analysis of the distal third of the right femur in the region proximal to the epiphyseal growth plate showed that heparin induces both a time- and dose-dependent decreased in trabecular bone volume, with the majority of trabecular bone loss occurring within the first 8 days of treatment. Thus, heparin doses of 1.0 U/g/d resulted in a 32% loss of trabecular bone. Heparin-treated rats also showed a 37% decrease in osteoblast surface as well as a 75% decrease in osteoid surface. In contrast, heparin treatment had the opposite effect on osteoclast surface, which was 43% higher in heparin-treated rats, as compared with that in control rats. Biochemical markers of bone turnover showed that heparin treatment produced a dose-dependent decrease in serum alkaline phosphatase and a transient increase in urinary PYD, thus confirming the histomorphometric data. Based on these observations, we conclude that heparin decreases trabecular bone volume both by decreasing the rate of bone formation and increasing the rate of bone resorption.

The effects of low molecular weight and standard heparin on calcium loss from fetal rat calvaria

Osteoporosis is a well-recognized complication of long-term heparin use. However, the mechanisms by which heparin can influence bone metabolism are unclear. We report here that unfractionated heparin stimulates the process of bone resorption and that the low molecular weight heparins (LMWHs), enoxaparin, fragmin, logiparin, and ardeparin produce significantly less calcium loss than unfractionated heparin. To assess calcium loss from bone, we quantified the release of 45Ca into the culture medium of fetal rat calvaria. 45Ca release was increased in a dose-dependent manner by the addition of either unfractionated heparin or the LMWHs; but more than 50-fold higher LMWH concentrations were required to obtain an equivalent effect to unfractionated heparin. Thus, at concentration > or = 2 micrograms/mL (0.35 anti-Xa units/mL), unfractionated heparin stimulated 45Ca release 1.53 +/- 0.06 fold. 45Ca release was increased to a similar extent by the addition of either 10(-7) mol/L parathyroid hormone (PTH) or 10(-6) mol/L 1,25 dihydroxyvitamin D3 (1,25 Vit D3). In contrast to unfractionated heparin, LMWH concentrations > or = 100 micrograms/mL (> or = 14.0 anti-Xa units/mL) were required before maximum isotope release was observed. At concentrations well above therapeutic levels, the LMWHs stimulated 45Ca release by only 1.25 /+- 0.01-fold. Heparins with high and low antithrombin III affinities stimulated 45Ca release equally well. Both size and sulfation were found to be major determinants of heparin's ability to promote isotope release. Thus, the ability of defined heparin fragments to stimulate 45Ca release correlated with their molecular weight, and after N-desulfation the ability of heparin to induce isotope release was greatly diminished. Dermatan sulfate had no effect on 45Ca release. We conclude that size and sulfation are major determinants of heparin's ability to promote bone resorption and that the risk of heparin-induced osteoporosis may be reduced by the use of LMWH preparations.

Adult onset Kawasaki disease diagnosed by the echocardiographic demonstration of coronary aneurysms

A 17-year-old boy presented with fever, bilateral conjunctival infection, angina and extensive cervical adenopathy. Amoxycillin was started. Ten days later he was admitted to hospital because of persistent high fever, cervical adenopathy, erythema of the pharynx and tongue and lip fissuration. The most important interventions of his first hospitalization were endotracheal intubation because of increasing dyspnoea due to adult respiratory distress syndrome and haemodialysis for renal insufficiency. His admission to our hospital was marked by the echocardiographic discovery of giant coronary aneurysms in the first few centimeters of both right and left coronary arteries. Coronary angiography confirmed giant aneurysm formation of the right and left coronary arteries. Similarly, medium sized arteries (cerebral, hepatic, mesenteric, iliac) presented abnormalities and laboratory findings. This is the first description of adult-onset Kawasaki disease with giant coronary aneurysm formation and more generalized arterial involvement. The severity of the clinical symptoms and the severity of the coronary disease indicates that Kawasaki disease of the adult does not always have a benign course.

A Double Multilayer Monochromator at an ESRF Undulator for Microbeam Experiments

A water-cooled double W/Si-multilayer monochromator has been operated at an ESRF low-beta undulator beam. For a fixed distance of the two multilayers the first-order Bragg reflection was at ~8 keV. The peak power density of the beam at the exit of the multilayers was ~1 W mm(-2) and the flux density of the first order after a 10 mum collimator was 4 x 10(5) photons s(-1) mum(-2) mA(-1.) The performance of the beam in microbeam diffraction has been tested on a 20 mum W wire. The observed pseudo-Laue pattern is discussed with respect to the multilayer spectrum.

Photon counting techniques with silicon avalanche photodiodes

The properties of avalanche photodiodes and associated electronics required for photon counting in the Geiger and the sub-Geiger modes are reviewed. When the Geiger mode is used, there are significant improvements reported in overall photon detection efficiencies (approaching 70% at 633 nm), and a timing jitter (under 200 ps) is achieved with passive quenching at high overvoltages (20-30 V). The results obtained by using an active-mode fast quench circuit capable of switching overvoltages as high as 15 V (giving photon detection efficiencies in the 50% range) with a dead time of less than 50 ns are reported. Larger diodes (up to 1 mm in diameter) that are usable in the Geiger mode and that have quantum efficiencies over 80% in the 500-800-nm range are also reported.

Resistance to photodynamic therapy in radiation induced fibrosarcoma-1 and Chinese hamster ovary-multi-drug resistant. Cells in vitro

A degree of resistance to photodynamic therapy (PDT) has been induced in radiation-induced fibrosarcoma-1 (RIF-1) tumor cells by repeated photodynamic treatment with Photofrin (4 or 18 h incubation) in vitro to the 0.1-1% survival level, followed by regrowth from single surviving colonies. The resistance is shown as increased cell survival in the strain designated RIF-8A, compared to the wild-type RIF-1 cells, when exposed to increasing Photofrin concentration for 18 h incubation and fixed light exposure. No difference was found between RIF-1 and RIF-8A in the uptake of Photofrin per unit cell volume at 18 h incubation. Resistance to PDT was also observed in Chinese hamster ovary-multi-drug resistant (CHO-MDR) cells compared to the wild-type CHO cells, possibly associated with decreased cellular concentration of Photofrin in the former. By contrast, the PDT-resistant RIF-8A cells did not show any cross-resistance to Adriamycin, nor was there any significant drug concentration difference between RIF-1 and RIF-8A. These findings suggest that different mechanisms are responsible for PDT-induced resistance and multi-drug resistance.

[Buerger's disease. Clinical and therapeutic review. Apropos of a case]

In reference to a typical case of Buerger's disease, the clinical, arteriographic, histological signs as well as diagnostic criteria are restated. The pathogenesis is still unknown; a genetic predisposition and an auto-immune process could be involved. The treatment, presently symptomatic, cannot arrest the evolution which is often mutilating, when the patient continues to smoke. An early diagnosis is possible in the presence of superficial phlebitis or Raynaud's phenomenon.

Keratoderma climactericum (Haxthausen's disease): clinical signs, laboratory findings and etretinate treatment in 10 patients

10 cases of keratoderma climactericum are reported. This keratosis of the palms and soles appears late in women of menopausal age. The keratotic lesions first develop at the plantar pressure points, making walking troublesome. Involvement of the hands remains discrete. Examination for contact allergy, fungal tests, vitamin A serum levels, and sex hormones were negative or normal in all the 10 patients. Microscopy revealed a lichenified eczema with evidence of mechanical irritation. Etretinate (0.78 mg/kg/day) brought about partial or total remission of the hyperkeratosis. Pain on walking disappeared in all the patients.