Effects of (+)-catechin on the function of osteoblastic cells

Tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) are candidate cytokines which are produced by osteoblastic linage cells and promote osteoblast apoptosis, osteoclastogenesis and bone resorption. Here, we examined the effect of (+)-catechin, one of the most common grape flavonols, on osteoblastic MC3T3-E1 cells. (+)-Catechin caused a significant elevation of cell survival at 10(-5) and 10(-4) M and alkaline phosphatase activity at 10(-5) M. Also, treatment with (+)-catechin (10(-5) M) decreased bone-resorbing cytokines (TNF-alpha and IL-6) production and apoptosis in osteoblasts. Our data indicate that the reduction of bone-resorbing cytokines and apoptosis in osteoblasts by (+)-catechin may result in the prevention and therapy for osteoporosis and inflammatory bone diseases.     

Bilateral diffuse lamellar keratitis following bilateral simultaneous versus sequential laser in situ keratomileusis

AIM: To determine the difference in the incidence of bilateral diffuse lamellar keratitis (DLK) in patients undergoing simultaneous versus sequential laser in situ keratomileusis (LASIK) as an indication of intrinsic risk for inflammation. METHODS: A retrospective non-comparative case series of 1632 eyes that had undergone bilateral, simultaneous or sequential LASIK between April 1998 and February 2001 at a university based refractive centre by three surgeons. All cases that developed clinically evident DLK were identified and reviewed. In order to identify isolated cases and exclude those caused by environmental factors, when more than one patient in a given session developed DLK, the session was excluded. The main outcome measure was the incidence of unilateral and bilateral isolated, non-epidemic DLK. RESULTS: Of 1632 eyes, 126 eyes (7.7%) of 107 patients developed at least grade 1 DLK. In six operating sessions, DLK was observed in more than one patient per session, and on this basis 13 patients were excluded. 16 of the 94 remaining patients developed DLK in both eyes (17.0%). Six of 41 patients (14.6%) in the simultaneous group, versus 10 of 53 patients (18.9%) in the sequential group developed bilateral DLK (p >0.5). CONCLUSION: In isolated, non-epidemic bilateral DLK, a similar incidence was observed regardless of whether the surgery was simultaneous or sequential, suggesting an underlying intrinsic cause for DLK.     

Isodiospyrin as a novel human DNA topoisomerase I inhibitor

Isodiospyrin is a natural product from the plant Diospyros morrisiana, which consists of an asymmetrical 1,2-binaphthoquinone chromophore. Isodiospyrin exhibits cytotoxic activity to tumor cell lines but very little is known about its cellular target and mechanism of action. Unlike the prototypic human topoisomerase I (htopo I) poison camptothecin, isodiospyrin does not induce htopo I-DNA covalent complexes. However, isodiospyrin antagonizes camptothecin-induced, htopo I-mediated DNA cleavage. Binding analysis indicated that isodiospyrin binds htopo I but not DNA. These results suggest that isodiospyrin inhibits htopo I by direct binding to htopo I, which limits htopo I access to the DNA substrate. Furthermore, isodiospyrin exhibits strong inhibitory effect on the kinase activity of htopo I toward splicing factor 2/alternate splicing factor in the absence of DNA. Thus, these findings have important implications on naphthoquinone and its derivatives' cellular mode of actions, i.e. these novel DNA topoisomerase I inhibitors can prevent both DNA relaxation and kinase activities of htopo I.     

Soluble guanylyl cyclase activator YC-1 inhibits human neutrophil functions through a cGMP-independent but cAMP-dependent pathway

3-(5'-Hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1), a novel type of soluble guanylyl cyclase (sGC) activator, is useful in investigating the signaling of cGMP and may provide a new approach for treating cardiovascular diseases. Herein, YC-1 was demonstrated to inhibit the generation of superoxide anion (O2-) and the release of beta-glucuronidase release, to diminish the membrane-associated p47phox and to accelerate resequestration of cytosolic calcium in formyl-l-methionyl-l-leucyl-l-phenylalanine-activated human neutrophils. YC-1 not only directly promoted sGC activity and cGMP formation but also dramatically potentiated sodium nitroprusside-induced sGC activity and cGMP formation in human neutrophils. However, the synergistic increase in the amount of cGMP was inconsistent with its cellular response. Moreover, neither an sGC inhibitor nor protein kinase G inhibitors reversed the inhibitory effect of YC-1. Interestingly, YC-1 also increased the cAMP concentration and protein kinase (PK)A activity. The inhibitory effect of YC-1 was significantly enhanced by prostaglandin (PG)E1 and isoproterenol, and almost abolished by PKA inhibitors. These results show that cAMP, but not cGMP, mediates the YC-1-induced inhibition of human neutrophils. YC-1 increased the PGE1- and forskolin-induced but not 3-isobutyl-1-methylxanthine-produced cAMP formation, suggesting inhibition of phosphodiesterase. These findings thus reveal novel mechanism-mediated anti-inflammatory properties of YC-1 in human neutrophils, which can influence the progression of cardiovascular disease. cAMP, but not cGMP, plays an important role in the regulation of respiratory burst and degranulation in human neutrophils.     

Assessing the toxicity of dodecylbenzene sulfonate to the midge Chironomus riparius using body residues as the dose metric

Dodecylbenzene sulfonate (DBS) is a component of linear alkylbenzene sulfonate (LAS), an anionic surfactant, mainly used in household detergents. Due to the large quantity of DBS in use, there is concern over adverse environmental effects. This work examined the toxicokinetics and toxicity of the 2-phenyl isomer of dodecylbenzene sulfonate in 4-d, 10-d, and partial life-cycle tests on the midge, Chironomus riparius, exposed to aqueous solutions. Toxicokinetics were determined in 10-d uptake and 5-d elimination tests. The toxicokinetics were based on parent compound concentration in water and yielded an uptake coefficient (ku) of 17.5 (14.87-20.20) ml/g/h, an elimination rate constant (ke) of 0.073 (0.062-0.085) per h, a bioconcentration factor (BCF) of 56 to 240, and a half-life (t 1/2) of 9.5 (8.0-11.0) h. Biotransformation measurements did not reveal evidence for DBS metabolism. Thus, body residues, determined in the toxicity study, represent parent compound. In toxicity tests, 4- and 10-d LR50s (the body residue required to cause 50% mortality) in live midges were 0.72 (0.65-0.79) and 0.18 (0.08-0.42) mmol/kg, respectively. Thirty-day LR50s were 0.18 (0.09-1.64) and 0.21 (0.15-0.39) mmol/kg in duplicate studies. Of the sublethal endpoints, only developmental time increase was significant, with the lowest-observed-effect residues of 0.085 (0.067-0.105) and 0.100 (0.087-0.114) mmol/kg for male and female midges, respectively. Deformities in surviving larvae were also observed as chronic responses for body residues exceeding the 30-d LR50. The body residues required for mortality suggest that DBS acts like a polar narcotic in the midge.     

Effect of sorption on benzene biodegradation in sandy soil

The effect of sorption on benzene biodegradation in sandy soil was studied by conducting kinetic microcosm batch tests in soil-free solution and in the presence or absence of bacteria in soil materials with varying degrees of powdered activated carbon (PAC). In the soil-free experiment, benzene was added to a solution inoculated with Pseudomonas aeruginosa bacteria in order to achieve a potential or maximum biodegradation rate. In subsequent experiments, benzene was applied to a solution containing sandy soil and various PAC contents with and without inoculating P. aeruginosa. Benzene concentrations in the soil-free experiments decreased with time with two characteristic rates. A two-stage exponential decay model adequately represented the observed solution concentration pattern with time. Sorption experiments in bacteria-free soil also decreased monotonically, with the extent of sorption increasing as PAC content increased. The sorption data were represented well with a two-stage irreversible sorption model. A third set of experiments in the presence of both soil and bacteria showed more rapid concentration loss from solution than the set of experiments with bacteria-free soil. A model combining sorption and degradation greatly overestimated the loss when the rate coefficient from the bacteria-free experiments was used. Satisfactory agreement between model predictions and observed values was obtained when the degradation rate coefficients were decreased by factors ranging from 3 to 10, depending on the amount of PAC present. Model predictions of the percentage benzene mass remaining in the soil after 25 d of degradation ranged from 72 to 97%, depending on the PAC content, compared to only 2.5% remaining in soil-free solution.     

Curcumin decreases the DNA adduct formation,arylamines N-acetyltransferase activity and gene expression in human colon tumor cells (colo 205)

The effects of curcumin on the N-acetyltransferase (NAT) activity, AF-DNA adduct formation and NAT gene expression were examined using the human colon tumor cell line (colo 205). Various concentrations of curcumin were added to the cytosols or to the medium of human colon tumor cells. The NAT activity was determined by high performance liquid chromatography assaying for the amounts of acetylated 2-aminofluorene (AAF) and p-aminobenzoic acid (N-Ac-PABA) and nonacetylated 2-aminofluorene (AF) and p-aminobenzoic acid (PABA). The NAT activity in the human colon tumor cells and cytosols was suppressed by curcumin in a dose-dependent manner. The results demonstrated that gene expression (NAT1 mRNA) in human colon tumor cells was inhibited by curcumin. The apparent values of Km and Vmax of NAT of human colon tumor cells were also decreased by curcumin in cytosols. Curcumin may act as a noncompetitive inhibitor. After the incubation of human colon tumor cells with AF with or without curcumin cotreatment, the cells were recovered and DNA was prepared, hydrolyzed to nucleotides, the adducted nucleotides were extracted into butanol and AF-DNA adducts analyzed by HPLC. The results also demonstrated that when curcumin was added to the media a decrease in AF-DNA adduct formation was seen in the human colon tumor cells. The finding of AF-DNA adduct formation in cultured human colon tumor cells suggests the usefulness of cultured cells for assessing arylamine-induced DNA damage.     

Growth factor releasing porous poly (ɛ-caprolactone)-chitosan matrices for enhanced bone regenerative rherapy

Drug releasing porous poly(epsilon-caprolactone) (PCL)-chitosan matrices were fabricated for bone regenerative therapy. Porous matrices made of biodegradable polymers have been playing a crucial role as bone substitutes and as tissue-engineered scaffolds in bone regenerative therapy. The matrices provided mechanical support for the developing tissue and enhanced tissue formation by releasing active agent in controlled manner. Chitosan was employed to enhance hydrophilicity and biocompatibility of the PCL matrices. PDGF-BB was incorporated into PCL-chitosan matrices to induce enhanced bone regeneration efficacy. PCL-chitosan matrices retained a porous structure with a 100-200 microm pore diameter that was suitable for cellular migration and osteoid ingrowth. NaHCO3 as a porogen was incorporated 5% ratio to polymer weight to form highly porous scaffolds. PDGF-BB was released from PCL-chitosan matrices maintaining therapeutic concentration for 4 week. High osteoblasts attachment level and proliferation was observed from PCL-chitosan matrices. Scanning electron microscopic examination indicated that cultured osteoblasts showed round form and spread pseudopods after 1 day and showed broad cytoplasmic extension after 14 days. PCL-chitosan matrices promoted bone regeneration and PDGF-BB loaded matrices obtained enhanced bone formation in rat calvarial defect. These results suggested that the PDGF-BB releasing PCL-chitosan porous matrices may be potentially used as tissue engineering scaffolds or bone substitutes with high bone regenerative efficacy.     

Chitosan microparticle preparation for controlled drug release by response surface methodology

The objectives were to investigate the effects of formulation variables on the release of drug and to optimize the formulation of chitosan microparticles loaded with drug for controlled release using response surface methodology. Chitosan microparticles were prepared by dropping a chitosan solution into sodium tripolyphosphate (TPP) through ionic cross-linking. The release behaviour of felodipine as a model drug was affected by preparation variables. A central composite design was used to evaluate and optimize the effect of preparation variables, chitosan concentration (X1), the pH of the TPP solution (X2) and cross-linking time (X3) on the cumulative per cent drug release (Y) in 24 h. Chitosan concentration and cross-linking time affected negatively the release of felodipine, while the pH of the TPP did so positively and was the highest influential factor. The optimum rate of drug release, 100% in 24 h, was achieved at 1.8% chitosan concentration, a pH 8.7 for the TPP solution and 9.7 min cross-linking time.