[MARY LYON (1925-2014) AND THE RANDOM INACTIVATION OF CHROMOSOME X].

Since the beginning of the last century, genetic research has been preoccupied with the dosage compensation question: What mechanism controls equal expression of chromosome X genes between females and males? In the 1950s, many discoveries occurred in the field of cytogenetics related to the sex chromatin of female mammals. Concomitantly, genetic information accumulated with regard to expression patterns of X-linked genes in female mice and the expression effect of translocations between chromosome X and autosomes. In addition, many case reports were published about families with sex-linked diseases. The lately deceased scientist Mary F. Lyon suggested a unifying theory of these findings. In her articles "Gene action in the X-chromosome of the mouse (Mus musculus L.T in 1961, and "Sex chromatin and gene action in the mammalian X-chromosome" in 1962, she suggested that: (1) the heteropyknotic chromosome X was genetically inactivated, (2) the inactivated chromosome X could be either paternal or maternal in origin in different cells of the same animal, and (3) the inactivation occurred early in embryonic development. This theory led to an immediate breakthrough in understanding the basic mechanisms responsible for X-linked diseases and solved many unexplained case studies. Moreover, the inquiry of the mechanism of the phenomenon promoted scientific understanding of a wide range of areas in molecular biology such as DNA methylation, the silencing mechanism by XIST, histone modifications, DNA replication timing and more. The current article deals with some biographical details about Mary F. Lyon, the background of her theory, her historical articles and the development of the field since.

Laboratory and clinical acute effects of active and passive indoor group water-pipe (narghile) smoking.

BACKGROUND: Indoor group water-pipe tobacco smoking, commonly referred to as water-pipe smoking (WPS), especially in coffee shops, has gained worldwide popularity. We performed a comprehensive laboratory and clinical evaluation of the acute effects of active and passive indoor group WPS. METHODS: This comparative study evaluated pre- and post-30-min active and passive indoor group WPS. The outcome parameters were carboxyhemoglobin (COHb), nicotine, and cotinine levels; CBC count; and cardiorespiratory parameters. Exhaled breath condensate (EBC) cytokines and endothelial function (using the EndoPat device [Itamar Medical Ltd]) were measured only in active smokers. Statistical methods used were Student t test, Wilcoxon signed rank test, Fisher exact test, analysis of variance, and Newman-Keuls post hoc test where relevant. RESULTS: Sixty-two volunteers aged 24.9±6.2 years were included; 47 were active smokers, and 15 were passive smokers. COHb level increased postactive WPS (active smokers, 2.0%±2.9% vs 17.6%±8.8%; P<.00001); six subjects (12.7%) had a >25% increase, and two subjects (4.2%) had a >40% increase. Plasma nicotine level increased postactive WPS (active smokers, 1.2±4.3 ng/mL vs 18.8±13.9 ng/mL; P<.0001); plasma cotinine and urinary nicotine and cotinine levels also increased significantly. EBC IL-4, IL-5, IL-10, IL-17, and γ-interferon decreased significantly with postactive smoking; endothelial function did not change. WPS was associated with adverse cardiorespiratory changes. In passive smokers, COHb level increased (0.8%±0.25% vs 1.2%±0.8%, respectively, P=.003) as did respiratory rate. CONCLUSIONS: One session of active indoor group WPS resulted in significant increases in COHb and serum nicotine levels (eightfold and 18-fold, respectively) and was associated with adverse cardiorespiratory health effects. The minor effects found in passive smokers suggest that they too may be affected adversely by exposure to WPS. The results call for action to limit the continuing global spread of WPS in coffee shops. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT1237548; URL: www.clinicaltrials.gov.

[Short-and long-term effects of cannabinoids on memory, cognition and mental illness].

Marijuana is considered the most commonly used drug in the world, with estimated millions of users. There is dissent in the medical world about the positive and negative effects of marijuana, and recently, a large research effort has been directed to that domain. The main influencing drug ingredient is THC, which acts on the cannabinoid system and binds to the CB1 receptor. The discovery of the receptor led to the finding of an endogenous ligand, anandamide, and another receptor-CB2. The researchers also discovered that cannabinoids have extensive biological activity, and its short and long-term effects may cause cognitive and emotional deficiencies. Findings show that the short-term effects, such as shortterm memory and verbal Learning, are reversible. However, despite the accumulation of evidence about long-term cognitive damage due to cannabis use, it is difficult to find unequivocal results, arising from the existence of many variables such as large differences between cannabis users, frequency of use, dosage and endogenous brain compensation. Apart from cognitive damage, current studies investigate how marijuana affects mental illness: a high correlation between cannabis use and schizophrenia was found and a high risk to undergo a psychotic attack. Furthermore, patients with schizophrenia who used cannabis showed a selective neuro-psychological disruption, and similar cognitive deficiencies and brain morphological changes were found among healthy cannabis users and schizophrenia patients. In contrast to the negative effects of marijuana including addiction, there are the medical uses: reducing pain, anxiety and nausea, increasing appetite and an anti-inflammatory activity. Medicalization of marijuana encourages frequent use, which may elevate depression.