The leaves of many trees emit biogenic volatile organic compounds (BVOCs) that protect them from various threats, including herbivory, pathogens, and heat stress. In a previous study, we analyzed the optimal seasonal schedule for producing isoprene, a highly volatile BVOC, in leaves to mitigate heat damage and maximize net carbon gain. In this paper, we investigate the seasonal production schedule of BVOCs stored in leaves, such as monoterpenes and sesquiterpenes, which decay slowly.
View Article and Find Full Text PDFThe leaves of many trees emit volatile organic compounds (abbreviated as BVOCs), which protect them from various damages, such as herbivory, pathogens, and heat stress. For example, isoprene is highly volatile and is known to enhance the resistance to heat stress. In this study, we analyze the optimal seasonal schedule for producing isoprene in leaves to mitigate damage.
View Article and Find Full Text PDFSome viruses exhibit "rebound" when the administration of antiviral drugs is discontinued. Viral rebound caused by resistance mutations or latent reservoirs has been studied mathematically. In this study, we investigated the viral rebound due to other causes.
View Article and Find Full Text PDFA high mutation rate of the RNA virus results in the emergence of novel mutants that may escape the immunity activated by the original (wild-type) strain. However, many of them go extinct because of the stochasticity due to the small initial number of infected cells. In a previous paper, we studied the probability of escaping stochastic extinction when the novel mutant has a faster rate of infection and when it is resistant to a drug that suppresses the wild-type virus.
View Article and Find Full Text PDFJ Theor Biol
September 2023
We study the effects of the immune system on multiple cancer colonies. When cancer cells proliferate, cytotoxic T lymphocytes (CTLs) reactive to the cancer-specific antigens are activated, suppressing the growth of cancer colonies. The immune reaction activated by a large cancer colony may suppress and eliminate smaller colonies.
View Article and Find Full Text PDFObjective: Inorganic pigments used as colouring agents in cosmetics (especially foundations) have many advantages over organic pigments, such as better opacity, weather and chemical resistance and lower cost. However, the types used in cosmetics are very limited, with various kinds of red, yellow and black iron oxide along with white titanium dioxide being the main materials. Ultramarine blue (UB) as a blue pigment and chromium oxide as a green pigment are also sometimes used in cosmetics.
View Article and Find Full Text PDFJ Theor Biol
February 2023
The coronavirus (SARS-CoV-2) exhibited waves of infection in 2020 and 2021 in Japan. The number of infected had multiple distinct peaks at intervals of several months. One possible process causing these waves of infection is people switching their activities in response to the prevalence of infection.
View Article and Find Full Text PDFAfter infecting a host, a viral strain may increase rapidly within the body and produce mutants with a faster proliferation rate than the virus itself. However, most of the mutants become extinct because of the stochasticity caused by the small number of infected cells. In addition, the mean growth rate of a mutant strain decreases with time because the number of susceptible target cells is reduced by the original strain.
View Article and Find Full Text PDFThe design of a new clinical candidate histamine-H(3) receptor antagonist for the potential treatment of excessive daytime sleepiness (EDS) is described. Phenethyl-R-2-methylpyrrolidine containing biphenylsulfonamide compounds were modified by replacement of the sulfonamide linkage with a sulfone. One compound from this series, 2j (APD916) increased wakefulness in rodents as measured by polysomnography with a duration of effect consistent with its pharmacokinetic properties.
View Article and Find Full Text PDFAntagonism of the histamine-H(3) receptor is one tactic being explored to increase wakefulness for the treatment of disorders such as excessive daytime sleepiness (EDS) as well as other sleep or cognitive disorders. Phenethyl-R-2-methylpyrrolidine containing biphenylsulfonamide compounds were shown to be potent and selective antagonists of the H(3) receptor. Several of these compounds demonstrated in vivo activity in a rat model of (R)-alpha-methyl histamine (RAMH) induced dipsogenia, and one compound (4e) provided an increase in wakefulness in rats as measured by polysomnographic methods.
View Article and Find Full Text PDFA new series of H(3) antagonists derived from the natural product Conessine are presented. Several compounds from these new series retain the potency and selectivity of earlier diamine based analogs while exhibiting improved PK characteristics. One compound (3u) demonstrated functional antagonism of the H(3) receptor in an in vivo pharmacological model.
View Article and Find Full Text PDFBioorg Med Chem Lett
February 2008
A new family of Histamine H(3) receptor antagonists (5a-t) has been prepared based on the structure of the natural product Conessine, a known H(3) antagonist. Several members of the new series are highly potent and selective binders of rat and human H(3) receptors and display inverse agonism at the human H(3) receptor. Compound 5n exhibited promising rat pharmacokinetic properties and demonstrated functional antagonism of the H(3) receptor in an in-vivo pharmacological model.
View Article and Find Full Text PDF[reaction: see text] Lindlar semihydrogenation of a vitamin D type trienyne leads spontaneously to 9 alpha,19-methano-1 alpha,25-dihydroxyvitamin D3. The intermediate tetraene resulting from the reduction undergoes a rapid, stereoselective 8pi electron electrocyclization affording a novel steroid containing a linearly fused ABC (six-eight-six) 1,3,5-cyclooctatriene carbon framework.
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