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Psilocybin is a tryptamine alkaloid found in some mushrooms, especially those of the genus Psilocybe. Psilocybin has four metabolites including the pharmacologically active primary metabolite psilocin, which readily enters the systemic circulation. The psychoactive effects of psilocin are believed to arise due to the partial agonist effects at the 5HT2A receptor. Psilocin also binds to various other receptor subtypes although the actions of psilocin at other receptors are not fully explored. Psilocybin administered at doses sufficient to cause hallucinogenic experiences has been trialed for addictive disorders, anxiety and depression. This review investigates studies of psilocybin and psilocin and assesses the potential for use of psilocybin and a treatment agent in neuropsychiatry. The potential for harm is also assessed, which may limit the use of psilocybin as a pharmacotherapy. Careful evaluation of the number needed to harm vs the number needed to treat will ultimately justify the potential clinical use of psilocybin. This field needs a responsible pathway forward.
The first demonstration of laser action in ruby was made in 1960 by T. H. Maiman of Hughes Research Laboratories, USA. Many laboratories worldwide began the search for lasers using different materials, operating at different wavelengths. In the UK, academia, industry and the central laboratories took up the challenge from the earliest days to develop these systems for a broad range of applications. This historical review looks at the contribution the UK has made to the advancement of the technology, the development of systems and components and their exploitation over the last 60 years.
Among potential endophenotypes proposed for bipolar affective disorder focusing on circadian abnormalities associated with the illness has particularly high face validity. Melatonin sensitivity to light is one circadian endophenotype proposed as useful in bipolar disorder. The aim of this study was to investigate melatonin sensitivity to light over a range of light intensities in order to compare and contrast responses in bipolar I patients with those of healthy adult volunteers.
The study included seven patients (4 females, 3 males) with bipolar I disorder and 34 control participants (22 females, 12 males) with no personal or family history of affective illness. Melatonin sensitivity to light was determined in all patients and participants across a range of light intensities (0, 200, 500 and 1000 lux).
The results indicated that patients showed melatonin super-sensitivity to light in comparison with controls, a response that was consistent across the entire light intensity range investigated.
The study provides further evidence for a super sensitive response in bipolar I patients and suggests that its potential usefulness as an endophenotypic marker of the illness is deserving of further research.
Timothy Lambert, Department of Psychological Medicine, University of Sydney, Royal Prince Alfred Hospital, Camperdown NSW, Australia,
Trevor R. Norman, Department of Psychiatry, University of Melbourne, Austin Hospital, Victoria, Australia
There is increasing awareness that ethnic and cultural influences can alter individual responses to medications (Lambert & Minas, 1998). Ethno-psychopharmacology investigates cultural variations and differences that influence the effectiveness of prescription medicines used in the treatment of mental illnesses. Differences in response can be explained by both genetic and psychosocial variations. They range from genetic variants in drug metabolism to cultural practices, which may affect diet, adherence to prescribed patterns of medication use, placebo response, and the simultaneous use of traditional and alternative healing methods (Lin et al., 1991).
However, predictions regarding genetic expression based on ethnicity alone need to be exercised with caution. Although connections between ethnicity and drug metabolism were recognized early, for example primaquine induced hemolysis based on G6PD deficiency in some Afro-Americans (Alving et al., 1956), such differences are based more on genetic endowment per se rather than racial or ethnic divisions. The validity of therapy based solely on racial differences has been questioned, for example, in relation to differential drug responses in cardiology for Black and White patients (Schwartz, 2001).
All populations irrespective of racial group exhibit substantial intra-population variability (Jorde & Wooding, 2004). Within a single racial population between 93 and 95% of all human genetic variability is captured (Jones & Perlis, 2006). A small amount of genetic variation (∼0.02% of all nucleotides) distinguishes populations from each other and no single marker can identify race or ancestry.