Drug-drug interactions

Several drugs are using to obtain a desired therapeutic objective or to treat coexisting diseases. The choice of drugs should be dependent on pharmacological characteristics. Interactions may be either pharmacokinetic or pharmacodynamic. In pharmacokinetic interaction, drugs may interact at any point during their absorption, distribution, metabolism, or excretion; the result may be an increase or decrease in the concentration of drug at the site of action. Metabolic enzyme, cytochrome P450, which metabolites any drugs is important in pharmacokinetic interaction. As characteristics change in their rates of disposition of using drug, the magnitude of an interaction that changes pharmacokinetic parameter is not always predictable but can be very significant. In pharmacodynamic interaction, drugs may interact at common receptor site or have additive or inhibitory effects due to actions at different sites in an organ. A drug interaction should be suspected danger when unexpected effects are observed. Careful drug histories are important, because patients may take over-the-counter drugs, may take drugs prescribed by another physician, or may take drugs prescribed for another patient. Care should be exercised when major changes are made in a drug regimen. Then, drugs that are not necessary should be discontinued. The major work of the medical staff of a hospital is to determine if an interaction has occurred and the magnitude of its effect. The interacting drugs should be used effectively with adjustment of dosage or other therapeutic modifications when an interaction is observed

Exact dimer ground state of the two dimensional Heisenberg spin system SrCu_2(BO_3)_2

The two dimensional Heisenberg model for SrCu_2(BO_3)_2 has the exact dimer ground state which was proven by Shastry and Sutherland almost twenty years ago. The critical value of the quantum phase transition from the dimer state to the N\'{e}el ordered state is determined. Analysis of the experimental data shows that SrCu_2(BO_3)_2 has the dimer ground state but is close to the transition point, which leads to the unusual temperature dependence of the susceptibility. Almost localized nature of the triplet excitations explains the plateaus observed in the magnetization curve.Comment: 4 pages, 5 figures, to appear in PR

Possible role of bradykinin on stimulus-secretion coupling in adrenal chromaffin cells

Nonapeptide bradykinin is known to be a central nervous system neurotrans-mitter and to play a role in regulation of neuronal function. However, few details are known of the function of its peptide on stimulus-secretion coupling in neuronal cells. In this article, the role of bradykinin on catecholamine biosynthesis, secretion and Ca2+movement in adrenal chromaffin cells as a model for catecholamine-containing neurons are examined. Bradykinin receptors are classified as B1 and B2 receptor subtypes. These receptors are present on the adrenal chromaffin cell membrane. Bradykinin increases the influx of Ca2+ and the turnover of phosphoinositide through the stimulation of bradykinin B2 receptor. The secretion of catecholamine from the cells is initiated by the raise of [Ca2+]i. An increase in [Ca2+]i and production of diacylglycerol stimulate the activation of calcium-dependent protein kinases. These kinases stimulate the activation of tyrosine hydroxylase, a rate-limiting enzyme in the biosynthesis of catecholamine. Otherwise, bradykinin increases Ca2+ efflux from the cells through the stimulation of the bradykinin-B2 receptor. This action may be explained by an extracellular Na+-dependent mechanism, probably through acceleration of Na+/Ca2+ exchange. It is interesting that bradykinin, which stimulates the biosynthesis and secretion of catecholamine in adrenal chromaffin cells, plays a role in the termination of calcium-signal transduction through the stimu-lation of Ca2+ efflux from the cells

Geological Research on the Bottom Sediments Sampled by the Fifth Japanese Antarctic Research Expedition

Results of soundings carried out during five Japanese Antarctic Research Expeditions are summarized. The bottom sediments collected by the 5th Expedition were analyzed concerning the grain size distribution, chemical composition, gravel composition, heavy mineral association, clay mineral composition and organic matters. The area studied is divisible into at least four sedimentary petrographic subprovinces on the basis of gravel composition, heavy mineral association and clay mineral composition. It is probable that these sediments were transported to the present sites from different sources without much sorting effects. The occurrence of trioctahedral illite in clay fraction may be the result of weak chemical weathering in the Antarctic region

TONS504-PHOTODYNAMIC THERAPY INDUCES CYTOTOXIC EFFECTS IN EMT6 CELLS

In the present study, TONS504 (C51H58N8O5I2; molecular weight, 1,116.9), a novel cationic hydrophilic photosensitizer, was synthesized from protoporphyrin IX dimethyl ester through a five‑step process according to a patented method for use in photodynamic therapy (PDT). The subcellular localization of TONS504 and the cytotoxic effects of TONS504‑mediated PDT in the mouse mammary tumor EMT6 cell line were investigated. TONS504 was localized primarily in the lysosomes and partially in the mitochondria. The cytotoxic effects of TONS504‑mediated PDT in the mouse mammary tumor EMT6 cell line were investigated using a WST8 assay and an Oxidative Stress kit. The cell viability values following treatment with 10 µg/ml TONS504 at light energies of 0, 1, 5 and 10 J/cm2 were 92.5, 101.8, 27.7 and 1.8%, respectively. The percentages of reactive oxygen species (ROS)(+) cells following the same treatment were 8.6, 8.5, 29.2 and 70.1%, respectively, whereas the percentages of apoptotic cells were 7.1, 5.6, 24.8 and 48.7%, respectively. The percentages of ROS(+) and apoptotic cells in the group subjected to TONS504‑mediated PDT increased in a manner dependent on the TONS504 concentration and light energy. Further studies are required to evaluate the in vivo pharmacokinetics, tissue distribution and photodynamic effects of TONS504

Adverse effect of donor-specific anti-human leukocyte antigen (HLA) antibodies directed at HLA-DP/-DQ on engraftment in cord blood transplantation

[Background aims] While donor-specific anti-human leukocyte antigen (HLA) antibodies (DSAs) in the recipient before transplantation are associated with graft failure in cord-blood transplantation (CBT), effects of DSAs other than against HLA-A, -B or -DRB1 on transplantation outcomes remained poorly understood. [Methods] We retrospectively analyzed 567 single-unit CBT recipients to evaluate impact of DSAs against HLA-DP and -DQ on CBT outcomes. [Results] Among 143 recipients (25.2%) who had anti-HLA antibodies, nine harbored DSAs against HLA-DP or -DQ. DSAs against HLA-DP or -DQ were associated with a significantly lower neutrophil engraftment rate (55.6% versus 91.8%, P = 0.032) and with a marginally lower platelet engraftment rate (46.7% versus 75.3%, P = 0.128) at day 100 after transplantation, compared with patients without anti-HLA antibodies. Time to neutrophil and platelet engraftment in patients with DSAs for HLA-DP or -DQ was significantly longer than that in patients without anti-HLA antibodies (median, 25 versus 21 days, P = 0.002 in neutrophil; median 61 versus 46 days, P = 0.014 in platelet). Cumulative incidence of bacterial infection at day 100 was significantly greater (88.9% versus 57.1%, P = 0.024), and re-transplant-free survival was marginally lower (55.6% versus 76.8%, P = 0.132) in patients with DSAs against HLA-DP or -DQ, compared with those without anti-HLA antibodies. These findings suggest that DSAs against HLA-DP or -DQ lead to unfavorable engraftment, which may increase risk of bacterial infection, and reduce survival soon after CBT. [Conclusions] Our results suggest the importance of evaluating DSAs against HLA-DP and -DQ in recipients before selecting CB units

Artesunate Enhances the Cytotoxicity of 5-Aminolevulinic Acid-Based Sonodynamic Therapy against Mouse Mammary Tumor Cells In Vitro

Sonodynamic therapy (SDT) kills tumor cells through the synergistic effects of ultrasound (US) and a sonosensitizer agent. 5-Aminolevulinic acid (5-ALA) has been used as a sonodynamic sensitizer for cancer treatment. However, studies have shown that 5-ALA-based SDT has limited efficacy against malignant tumors. In this study, we examined whether artesunate (ART) could enhance the cytotoxicity of 5-ALA-based SDT against mouse mammary tumor (EMT-6) cells in vitro. In the ART, ART + US, ART + 5-ALA, and ART + 5-ALA + US groups, the cell survival rate correlated with ART concentration, and decreased with increasing concentrations of ART. Morphologically, many apoptotic and necrotic cells were observed in the ART + 5-ALA + US group. The percentage of reactive oxygen species-positive cells in the ART + 5-ALA + US group was also significantly higher than that in the 5-ALA group (p = 0.0228), and the cell death induced by ART + 5-ALA + US could be inhibited by the antioxidant N-acetylcysteine. These results show that ART offers great potential in enhancing the efficacy of 5-ALA-based SDT for the treatment of cancer. However, these results are only based on in vitro studies, and further in vivo studies are required

Effects of Oral Glucosamine Hydrochloride Administration on Plasma Free Amino Acid Concentrations in Dogs

We examined the effects of oral glucosamine hydrochloride (GlcN), N-acetyl-d-glucosamine (GlcNAc) and d-glucose (Glc) administration on plasma total free amino acid (PFAA) concentrations in dogs. The PFAA concentrations increased in the control group and the GlcNAc group at one hour after feeding, and each amino acid concentration increased. On the other hand, in the GlcN group and the Glc group PFAA concentrations decreased at one hour after feeding. A significant decrease in amino acid concentration was observed for glutamate, glycine and alanine. Our results suggest the existence of differences in PFAA dynamics after oral administration of GlcN and GlcNAc in dogs

Emergence of Dynamically-Disordered Phases During Fast Oxygen Deintercalation Reaction of Layered Perovskite

Determination of a reaction pathway is an important issue for the optimization of reactions. However, reactions in solid-state compounds have remained poorly understood because of their complexity and technical limitations. Here, using state-of-the-art high-speed time-resolved synchrotron X-ray techniques, the topochemical solid-gas reduction mechanisms in layered perovskite Sr3Fe2O7−δ (from δ ∼ 0.4 to δ = 1.0), which is promising for an environmental catalyst material is revealed. Pristine Sr3Fe2O7−δ shows a gradual single-phase structural evolution during reduction, indicating that the reaction continuously proceeds through thermodynamically stable phases. In contrast, a nonequilibrium dynamically-disordered phase emerges a few seconds before a first-order transition during the reduction of a Pd-loaded sample. This drastic change in the reaction pathway can be explained by a change in the rate-determining step. The synchrotron X-ray technique can be applied to various solid-gas reactions and provides an opportunity for gaining a better understanding and optimizing reactions in solid-state compounds