Is provitamin D a UV-B receptor in plants?

An hypothesis is presented that provitamin D (dehydrocholesterol and/or ergosterol) can act as a UV-B receptor in plants and algae. We also propose that the proportions between provitamins D, previtamins D, and vitamins D (D₂ and D₃), after calibration, can be used to evaluate UV-B exposure of phytoplankton and terrestrial vegetation.     

Long-term changes in the marine macroalgae of Lågskär, Åland Sea (N Baltic)

Species composition, abundance and depth distribution of marine macroalgae were studied at Lågskär, the Åland Sea, in August 1993. Altogether, 26 species were identified and the most diverse vegetation, comprising 18 species, was recorded at a depth of 4–7 m. Comparison with the results obtained by Andersson in 1956 indicates that the total number of species had decreased by 6, and that the best developed and most diverse algal vegetation was then recorded at a depth of 10–15 m. In 1993 species such as Aglaothamnion roseum, Audouinella efflorescens, Phyllophora pseudoceranoides, Halopteris scoparia and Sphacelaria plumigera had disappeared, or were not recorded. Sphacelaria arctica, Cladophora rupestris, Stictyosiphon tortilis and Polysiphonia fucoides , in the 1950s important and dominating species, were greatly reduced in number. However, Pilayella littoralis, Ectocarpus siliculosus, Fucus vesioculosus and Rhodomela confervoides had increased. Compared with the drastic phytobenthic changes recorded in many coastal areas of the Baltic, the changes in the offshore Lågskär area are of minor extent.     

Stimulation of the insulin secretory mechanism following barium accumulation in pancreatic beta-cells

Electrothermal atomic absorption spectroscopy was employed for measuring barium in beta-cell-rich pancreatic islets microdissected from ob/ob-mice. Both the uptake and efflux of barium displayed two distinct phases. There was a 4-fold accumulation of barium into intracellular stores when its extracellular concentration was 0.26 mM. Unlike divalent cations with more extensive intracellular accumulation, the washout of Ba2+ was not inhibited by D-glucose. Ba2+ served as a substitute for Ca2+ both in maintaining the glucose metabolism after removal of extracellular Ca2+ and making it possible for glucose to stimulate insulin release. Furthermore, Ba2+ elicited insulin release in the absence of glucose and other secretagogues. The latter effect was reversible and was markedly potentiated under conditions known to increase the beta-cell content of cyclic AMP. It is likely that the observed actions of Ba2+ are mediated by Ca2+, since Ca2+ -dependent regulatory proteins, such as calmodulin, apparently cannot bind Ba2+ specifically.     

Dental anxiety among middle-aged and elderly women in Sweden. A study of oral state,utilisation of dental services and concomitant factors

The aim of this project was to investigate dental anxiety and its expression in utilisation of dental services, oral health and oral symptoms. In a cross-sectional study of women's health in Göteborg (population 432,000), Sweden, 1016 women aged 38 to 84 years participated. This randomly selected population took part in a series of investigative procedures including medical and dental clinical examinations, interviews and questionnaires. Levels of dental anxiety were measured on the Corah Dental Anxiety Scale (DAS). The average DAS score obtained was 7.2. The study showed that older women were significantly less anxious than younger ones. Severe dental anxiety (DAS 15) was experienced by 3.9% of the participants. This frequency corresponds well with findings by Hällström and Halling in their analysis of data from the first Göteborg study of women's health 24 years ago. High levels of dental anxiety were correlated with longer intervals between dental visits, poorer oral function and aesthetics and a higher frequency of oral symptoms. Headaches were more prevalent in the younger age groups and a correlation with dental anxiety was revealed. Our previous studies have shown that symptoms such as tension headaches are prevalent among dental phobic patients and that they are reported to be reduced by therapy for dental fear. The clinical and radiographical examinations revealed a generally poorer oral status, with a statistically significant higher number of decayed teeth among women with high dental anxiety.     

In Vivo Formation of 5-Methoxytryptamine from Melatonin in Rat

Abstract: Deacetylation of melatonin to 5-methoxytryptamine (5-MT) in vitro and in vivo was investigated in rat liver and brain tissue, using a gas chromatographic-mass spectrometric 5-MT assay method. In vitro incubation of liver but not brain (hypothalamic, mesencephalic) slices with melatonin led to a concentration-dependent formation of small amounts of 5-MT; the conversion being 0.3–0.8%. In vivo administration of melatonin resulted in a dose-dependent formation of 5-MT in small quantities in the liver. The time course showed a peak maximum within 0.5 h, with a rapid decline; the half-life being about 1 h. 5-MT could be detected in both the blood and the hypothalamus after in vivo injection of melatonin. The time course of 5-MT in the blood was similar to that in the liver, but 5-MT could only be detected in the hypothalamus after large doses shortly after the melatonin injection. MAO had to be inhibited both in the in vitro and in vivo experiments in order to recover 5-MT, indicating that formed 5-MT is normally rapidly metabolised by MAO. It is concluded that a small fraction of melatonin can be converted to 5-MT by deacetylation (by aryl acylamidase) in the liver in vivo , constituting a minor pathway. Such a pathway could not be demonstrated in the brain. Trace amounts of 5-MT previously reported to be present in various tissues could originate from deacetylation of melatonin in the liver and possibly some other peripheral organs known to contain the deacetylating enzyme. The present results indicate that peripherally formed 5-MT, a psychoactive compound, is unlikely to have any effect on brain function under normal circumstances.     

Biogenic Aldehydes in Brain: On Their Preparation and Reactions with Rat Brain Tissue

When 1 mM serotonin, dopamine, or norepinephrine was incubated with a monoamine oxidase preparation (mitochondrial membranes) in the presence of 4 mM sodium bisulfite, 85-95% of the amines were oxidized to the corresponding aldehydes. In the absence of bisulfite, the recoveries were only approximately 30%, and dark colored products were formed during the incubations. The aldehydes derived from tyramine, octopamine, methoxytyramine, and normetanephrine were also prepared by the use of this method. The bisulfite-aldehyde compounds were stable during storage at -20 degrees C. Bisulfite-free aldehyde solutions were made by diethylether extraction. When the aldehydes derived from dopamine or serotonin were incubated with rat brain homogenates, they were found to disappear in an aldehyde dehydrogenase- and aldehyde reductase-independent manner. The disappearance of the latter aldehyde was more pronounced, and the results indicated that this aldehyde may react with both proteins and phospholipids.     

Aeroallergen Immunoblotting with Human IgE Antibody

A new method is presented for the identification of the causative pollen of pollinosis patients. The airborne sample collected with a Burkard sampler was cut into two equal halves lengthwise. One was treated with the pollinosis patient's IgE using an indirect immunoenzymatic technique applied avidin-biotin system. The other half of the sampling tape was stained with basic fuchsin solution and the major pollen types were counted morphologically. The spot obtained and individual pollen counts were compared consecutively, and the causative pollen for the patient was estimated. Furthermore, verification was performed using the reference pollen of the estimated causative pollen. The method does not require any diagnostic extracts and needs only a small number of intact pollen grains. It is suitable for the identification of the causative pollen in rare pollinosis cases and the pollen for which a diagnostic extract is not commercially available.     

Cytosolic replication in epithelial cells fuels intestinal expansion and chronic fecal shedding of Salmonella Typhimurium

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