Morning Melatonin Has Limited Benefit as a Soporific For Daytime Sleep After Night Work

Exogenous melatonin administration in humans is known to exert both chronobiotic (phase shifting) and soporific effects. In a previous study in our lab, young, healthy, subjects worked five consecutive simulated night shifts (23:00 to 07:00 h) and slept during the day (08:30 to 15:30 h). Large phase delays of various magnitudes were produced by the study interventions, which included bright light exposure during the night shifts, as assessed by the dim light melatonin onset (DLMO) before (baseline) and after (final) the five night shifts. Subjects also ingested either 1.8 mg sustained‐release melatonin or placebo before daytime sleep. Although melatonin at this time should delay the circadian clock, this previous study found that it did not increase the magnitude of phase delays. To determine whether melatonin had a soporific effect, we controlled the various magnitudes of phase delay produced by the other study interventions. Melatonin (n=18) and placebo (n=18) groups were formed by matching a melatonin participant with a placebo participant that had a similar baseline and final DLMO (±1 h). Sleep log measurements of total sleep time (TST) and actigraphic measurements of sleep latency, TST, and three movement indices for the two groups were examined. Although melatonin was associated with small improvements in sleep quality and quantity, the differences were not statistically significant by analysis of variance. However, binomial analysis indicated that melatonin participants were more likely to sleep better than their placebo counterparts on some days with some measures. It was concluded that, the soporific effect of melatonin is small when administered prior to 7 h daytime sleep periods following night shift work.     

The Psychological and Physiological Effects of Using a Therapy Dog in Mindfulness Training

ABSTRACT

The present study was a randomized controlled trial examining the psychological and physiological effects of adding animal-assisted therapy (AAT) to a modified Mindfulness-Based Stress Reduction program (MBSR) for clients experiencing psychological distress. It was hypothesized that AAT would complement mindfulness-based interventions because the therapy dog will provide a focus for attention to the current experience and exemplify acceptance and “being,” enabling the understanding and practice of the main aspects of mindfulness. Participants (n=21) were randomly assigned to an MBSR or MBSR+AAT group and then completed an intervention consisting of six 50-minute individual therapy sessions. Each session included didactic and experiential components modified for delivery with or without a certified therapy dog. State and trait mindfulness, psychological distress measures, blood pressure, and heart rate were assessed at each session. Results indicate that all participants experienced fewer anxiety and depressive symptoms, decreased psychological distress, and increased mindfulness skills from preto post-treatment. Additionally, state anxiety, blood pressure, and heart rate decreased within sessions. No significant difference was found between the control and experimental groups, indicating that interaction with a therapy dog had no impact on symptom reduction, skill acquisition, or client satisfaction in the current study. However, moderate to large effect size estimates indicate clinically significant differences between groups, with higher ratings for the MBSR+AAT group on therapist efficacy, recommending the training, and participating in future treatment. Future studies need to increase methodological rigor by including multiple therapist/dog teams and increasing sample size. Moreover, researchers must more thoroughly examine the role the dog might have in altering the social environment, such as reducing stigma surrounding mental health services and enhancing the therapeutic alliance.     

Importance of the C2, N7, and C8 positions to the mutagenic potential of 8-Oxo-2'-deoxyguanosine with two A family polymerases

8-Oxo-2'-deoxyguanosine (OdG) is a prominent DNA lesion produced from the reaction of 2'-deoxyguanosine (dG) with reactive oxygen species. While dG directs the insertion of only dCTP during replication, OdG can direct the insertion of either dCTP or dATP, allowing for the production of dG → dT transversions. When replicated by Klenow fragment-exo (KF-exo), OdG preferentially directs the incorporation of dCTP over dATP, thus decreasing its mutagenic potential. However, when replicated by a highly related polymerase, the large fragment of polymerase I from Bacillus stearothermophilus (BF), dATP incorporation is preferred, and a higher mutagenic potential results. To gain insight into the reasons for this opposite preference and the effects of the C2, N7, and C8 positions on OdG mutagenicity, single-nucleotide insertions of dCTP and/or dATP opposite dG, OdG, and seven of their analogues were examined by steady state kinetics with both KF-exo and BF. Results from these studies suggest that the two enzymes behave similarly and are both sensitive not only to steric and electronic changes within the imidazole ring during both dCTP and dATP incorporation but also to the presence of the C2-exocyclic amine during dATP incorporation. The difference in incorporation preference opposite OdG appears to be due to a somewhat increased sensitivity to structural perturbations during dCTP incorporation with BF. Single-nucleotide extensions past the resulting base pairs were also studied and were not only similar between the two enzymes but also consistent with published ternary crystallographic studies with BF. These results are analyzed in the context of previous biochemical and structural studies, as well as stability studies with the resulting base pairs.     

Effects of Different Rearing Strategies and Ages on Levels of Natural Antibodies in Saliva of the Philippine Crocodile

The endemic Philippine crocodile(Crocodylus mindorensis) is a relatively small, critically endangered freshwater crocodile. In a head start program, crocodile hatchlings are caught in the wild, reared in captivity, and released back into the wild after two years. The current study aimed to determine optimal rearing strategies of Philippine crocodile hatchlings, including identification of possible diseases during rearing, and studying the effect of ages on natural antibody(NAb) levels. Thirty Philippine crocodiles were divided into two groups, half were reared with a hiding board, and half without the hiding board. Both groups received three different kinds of diets: meat, shrimp, or a combination of both. Saliva samples of the crocodiles were taken three times over a period of three months to test for NAb levels. Saliva samples were also taken from older crocodiles and crocodiles from different locations. NAb titres were compared to sheep red blood cells. Each time saliva samples were taken, a health check was done. The results showed that crocodiles would prefer the hiding board, and neither housing nor diet could affect the level of NAb titres in saliva. A positive correlation was found between NAb titres and body size, weight and age. Wild hatchlings had higher NAb titres than the hatchlings born in captivity, but the difference diminished with ageing. Five different diseases were found.     

The HtrA protease of Borrelia burgdorferi degrades outer membrane protein BmpD and chemotaxis phosphatase CheX

Borrelia burgdorferi, the spirochaetal agent of Lyme disease, codes for a single HtrA protein, HtrABb (BB0104) that is homologous to DegP of Escherichia coli (41% amino acid identity). HtrABb shows physical and biochemical similarities to DegP in that it has the trimer as its fundamental unit and can degrade casein via its catalytic serine. Recombinant HtrABb exhibits proteolytic activity in vitro, while a mutant (HtrABbS198A) does not. However, HtrABb and DegP have some important differences as well. Native HtrABb occurs in both membrane‐bound and soluble forms. Despite its homology to DegP, HtrABb could not complement an E. coli DegP deletion mutant. Late stage Lyme disease patients, as well as infected mice and rabbits developed a robust antibody response to HtrABb, indicating that it is a B‐cell antigen. In co‐immunoprecipitation studies, a number of potential binding partners for HtrABb were identified, as well as two specific proteolytic substrates, basic membrane protein D (BmpD/BB0385) and chemotaxis signal transduction phosphatase CheX (BB0671). HtrABb may function in regulating outer membrane lipoproteins and in modulating the chemotactic response of B. burgdorferi.     

Microorganisms form exocellular structures, trophosomes, to facilitate biodegradation of oil in aqueous media

Cytochemical staining and microscopy were used to study the trophic structures and cellular morphotypes that are produced during the colonization of oil-water interfaces by oil-degrading yeasts and bacteria. Among the microorganisms studied here, the yeasts (Schwanniomyces occidentalis, Torulopsis candida, Candida tropicalis, Candida lipolytica, Candida maltosa, Candida paralipolytica) and two representative bacteria (Rhodococcus sp. and Pseudomonas putida) produced exocellular structures composed of biopolymers during growth on petroleum hydrocarbons. Four of the yeasts including S. occidentalis, T. candida, C. tropicalis and C. maltosa excreted polymers through modified sites in their cell wall ('canals'), whereas C. lipolytica and C. paralipolytica and the two bacterial species secreted polymers over the entire cell surface. These polymers took the form of fibrils and films that clogged pores and cavities on the surfaces of the oil droplets. A three-dimensional reconstruction of the cavities using serial thin sections showed that the exopolymer films isolated the ambient aqueous medium together with microbial cells and oil to form both closed and open granules that contained pools of oxidative enzymes utilized for the degradation of the oil hydrocarbons. The formation of such granules, or 'trophosomes,' appears to be a fundamental process that facilitates the efficient degradation of oil in aqueous media.     

Nocturne for an unknown pollinator: first description of a night‐flowering orchid (Bulbophyllum nocturnum)

Bulbophyllum nocturnum , a species of section Epicrianthes from New Britain, is described and illustrated. It is the first known example of an orchid species in which the flowers open after dark and close in the morning. The poorly understood pollination biology of section Epicrianthes, a clade with highly unusual flowers, is discussed. Attention is drawn to the close resemblance between the petal appendages of some species and the fruiting bodies of certain Myxogastria. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 344–350.     

Isolating conifer DNA: A superior polysaccharide elimination method

Genomic DNA was isolated from frozen needles of maturePinus radiata clones using a modified extraction technique incorporating cetyltrimethylammonium bromide (CTAB) for cell lysis. A high sodium chloride concentration (2 M) was used at 2 stages of the extraction procedure to eradicate polysaccharides, yielding pure genomic DNA suitable for restriction enzyme digestion and PCR amplification. Extractions were scaled down to suit 1.5-mL Eppendorf tubes, allowing easier handling and enhanced sterility.