Metabolism of 8-prenylnaringenin, a potent phytoestrogen from hops (Humulus lupulus), by human liver microsomes.

The female flowers of hops are used throughout the world as a flavoring agent for beer. Recently, there has been increasing interest in the potential estrogenic properties of hop extracts. Among the possible estrogenic compounds in hops, 8-prenylnaringenin is perhaps most significant due to its high in vitro potency exceeding that of other known phytoestrogens. Since data regarding the pharmacokinetic properties of this compound are lacking, we investigated the in vitro metabolism of 8-prenylnaringenin by human liver microsomes. A total of 12 metabolites were identified, and biotransformation occurred on the prenyl group and the flavanone skeleton. The major site of oxidation was on the terminal methyl groups, and of the two possible isomers, the transisomer was more abundant. The double bond on the prenyl group was also oxidized to an epoxide that was opened by intramolecular reaction with the neighboring hydroxyl group. On the flavanone skeleton, the major site of oxidation was at 3'position on the B ring. Other metabolites included oxidation at carbon-3 as well as desaturation of the C ring to produce 8-prenylapigenin. An unusual hydroxy quinone product formed by ipso hydroxylation of the B ring of 8-prenylnaringenin was also detected. This product was probably an intermediate for the B ring cleavage product, 8-prenylchromone.     

Effects of unfractionated heparin, low molecular weight heparin and r-hirudin on leukocyte adhesion in ischemia/reperfusion.

Activation of the coagulation cascade during myocardial ischemia and reperfusion may contribute to the post-ischemic inflammatory response, mostly via generation of thrombin. We assessed the effect of the anticoagulants unfractionated heparin (UFH), low molecular weight heparin (LMWH) and r-hirudin on leukocyte adhesion and emigration after ischemia and reperfusion in rats. The rat cremaster muscle was prepared for intravital microscopy. One hundred and twenty minutes of ischemia were followed by 90 min of reperfusion. Saline (control), UFH, LMWH or r-hirudin were given 15 min prior to reperfusion and infused for the rest of the observation period. Dosages per kilogram of body weight were (bolus, infusion): saline, 3 ml, 3 ml/h; UFH, 400 IU, 100 IU/h; LMWH, 100 IU, 3 ml/h saline; or r-hirudin, 0.3 mg, 0.15 mg/h. In collecting venules, rolling, adherent, and extravasated leukocytes were counted from recordings of the intravital microscopy. All three anticoagulants similarly attenuated post-ischemic endothelial leukocyte adhesion. In contrast, emigration of leukocytes was only attenuated by r-hirudin. The emigration efficiency of adherent leukocytes (control, 1.21) was unchanged after UFH (1.74), and LMWH (1.51) but decreased after r-hirudin treatment (0.12). The different efficacy of the three anticoagulants in affecting emigration of adherent leukocytes suggests a specific role for the direct thrombin inhibitor r-hirudin in attenuating the post-ischemic inflammatory response. This effect may contribute to the benefits of direct thrombin inhibitors seen in clinical studies after treatment for acute coronary syndromes.     

In Vitro and In Vivo Biocompatibility of Novel Zwitterionic Poly(Beta Amino)Ester Hydrogels Based on Diacrylate and Glycine for Site‐Specific Controlled Drug Release

New (β‐aminoester) hydrogels (PBAE) based on di(ethylene glycol)diacrylate and glycine are successfully synthesized and characterized for the first time in this work. PBAE macromers are obtained using Michael addition. By changing the diacrylate/amine stoichiometric ratio, but maintaining it >1, samples with different chemical structure containing acrylate end‐groups are obtained. The hydrogels are synthesized from macromers utilizing free radical polymerization. Chemical structure of macromers and hydrogels is confirmed by proton nuclear magnetic resonance, and Fourier transform infra‐red spectroscopy. Swelling and degradation rates in physiological pH range change notably with pH and monomer molar ratio, validating pH sensitivity and zwitterionic behavior, which can be finely tuned by changing any of these parameters. In vitro cytotoxicity and in vivo acute embryotoxicity in zebrafish (Danio rerio) performed to assess the biocompatibility of the novel hydrogel materials and their degradation products reveal that materials are nontoxic and biocompatible. The Cephalexin in vitro drug release study, at pH values 2.20, 5.50, and 7.40, demonstrates pH‐sensitive delivery with the release profiles effectively controlled by pH and the hydrogel composition. PBAE hydrogels exhibit great potential for a variety of biomedical applications, including tissue regeneration and intelligent drug delivery systems.     

Altered and conventional fractionated radiotherapy in locoregional control and survival of patients with squamous cell carcinoma of the larynx, oropharynx, and hypopharynx

Aim

To compare the efficacy of two altered fractionation radiotherapy treatment protocols (hyperfractionation and accelerated fractionation with concomitant boost) with conventional fractionation in improvement of locoregional disease control and survival of patients with squamous cell carcinoma of the larynx, oropharynx, or hypopharynx.

Methods

From March 1999 to December 2000, 51 patients with previously untreated squamous cell carcinoma of the larynx, oropharynx or hypopharynx underwent conventionally fractionated radiotherapy and received 66-70 Gy in 6˝-7 weeks (2 Gy per fraction a day, 5 fractions a week). From January 2001 to June 2004, 101 patients with the same diagnoses underwent either hyperfractionated radiotherapy, with 74.4-79.2 Gy delivered in 6.2-7 weeks (1.2 Gy per fraction twice a day), or accelerated fractionation with concomitant boost, which delivered 68.7-72 Gy in 6 weeks (1.8 Gy per fraction a day and 1.5 Gy per fraction a day to a boost filed as a second daily treatment for the last 11-12 treatment days). Locoregional relapse and overall survival were recorded.

Results

Complete response to treatment was obtained in 31 of 51 patients treated with conventional fractionation, 33 of 50 patients treated with hyperfractionation, and 36 of 51 patients treated with accelerated fractionation. No significant differences were observed among the patients treated with conventional, hyperfractionated, or accelerated radiotherapy modalities either in locoregional control rate (41% vs 35% vs 49%, respectively; P = 0.690) or overall survival rate (50% vs 40% vs 51%, respectively; P = 0.760). The grade of acute reactions of the larynx significantly differed among the treatment groups (Fisher exact test; P = 0.039). The difference in the grade of acute side effects in the skin among the treatment groups was of borderline significance (χ²₂ test; P = 0.054). There was also a borderline difference among the groups in the grade of late side effects in the mucous membrane (χ²₂ test; P = 0.055).

Conclusion

Altered fractionation regimens were not more efficacious than conventional fractionation in the treatment of previously untreated head and neck carcinoma.

Clinical Trial Registration

ClinicalTrials.gov Identifier: {"type":"clinical-trial","attrs":{"text":"NCT00291434","term_id":"NCT00291434"}}NCT00291434Irrespectively of the modality of primary treatment for head and neck squamous cell carcinoma, local or locoregional residual or recurrent tumors represent the major cause of treatment failure, emphasizing the role of locoregional control for the patients’ long-term survival (1). Primary definitive radiotherapy used as a single treatment modality in patients with head and neck cancer is expected to allow preservation of the form and function of organs in this region (2). Primary definitive radiotherapy in the treatment of early stages of squamous cell carcinoma of the larynx, oropharynx or hypopharynx achieves equal probability of tumor control as surgery does. Large primary tumors and/or advanced neck disease treated with primary definitive radiotherapy demand delivery of large total doses of irradiation to enhance the tumor control. Considering the results of conventionally fractionated radiotherapy, rational modification of radiation fractionation regimens has been intensively investigated for more than three decades, with an aim to improve the outcome of patients with locally advanced head and neck carcinomas (3).The two prototypes of altered radiation fractionation regimens are hyperfractionation and accelerated fractionation. Hyperfractionation increases locoregional control of the diseases by increasing total tumor dose delivered, whereas accelerated fractionation should increase the control by counteracting the accelerated tumor clonogen proliferation during irradiation and uses a shortened overall treatment time (4-6). Large randomized trials showed that a number of altered fractionation schedules improved the locoregional control rates, but had only a modest impact on survival (7,8).The aim of our study was to evaluate two different altered fractionation regimens – hyperfractionation and accelerated fractionation with concomitant boost as a late accelerating component – in comparison with conventional fractionation in primary definitive radiotherapy of patients with squamous cell carcinomas of the larynx, oropharynx or hypopharynx.     

The polymerisation kinetics of lower dialkyl itaconates

The free radical polymerisation kinetics of diethyl- (DEI), dipropyl- (DnPI), dibutyl- (DnBI), and dihexyl itaconate (DHI) in the bulk were studied in the temperature range from 50 to 70°C. The concentration of the initiator, 2,2′-azoisobutyronitrile (AIBN), was varied between 0.02 and 0.085 mol/dm³. The rate of polymerisation (R_p), degree of polymerisation (DP), overall polymerization rate constant (K), the ratio of the propagation and termination rate constants (k_p/k_t^1/2), as well as the chain transfer constant to monomer (C_M) were determined. The values of R_p, K, and k_p/k_t^1/2 of the investigated monomers all increase with increasing size of the alkyl group in the ester substituent, whereas C_M decreases when going from the dimethyl to the dihexyl ester. The values of C_M are larger than the corresponding values for the alkyl esters of methacrylic acid.     

Synthesis of Abyssinone II and related compounds as potential chemopreventive agents

A facile and efficient approach to the synthesis of prenylated flavonoids as potential chemopreventive agents has been described. This features the synthesis of prenyl halide, prenylation of p-hydroxybenzaldehyde, formation of prenylated polyhydroxychalcone and cyclization of prenylated polyhydroxychalcone to flavanones (15) and (16), and flavonol (17) starting from isoprene (1). The structures of all three compounds have been characterized by NMR, IR and mass spectroscopy.     

Protective effects of nonionic triblock copolymers on bile acid-mediated epithelial barrier disruption

Translocation of bacteria and other luminal factors from the intestine following surgical injury can be a major driver of critical illness. Bile acids have been shown to play a key role in the loss of intestinal epithelial barrier function during states of host stress. Experiments to study the ability of nonionic block copolymers to abrogate barrier failure in response to bile acid exposure are described. In vitro experiments were performed with the bile salt sodium deoxycholate on Caco-2 enterocyte monolayers using transepithelial electrical resistance to assay barrier function. A bisphenol A coupled triblock polyethylene glycol (PEG), PEG 15-20, was shown to prevent sodium deoxycholate-induced barrier failure. Enzyme-linked immunosorbent assay, lactate dehydrogenase, and caspase 3-based cell death detection assays demonstrated that bile acid-induced apoptosis and necrosis were prevented with PEG 15-20. Immunofluorescence microscopic visualization of the tight junctional protein zonula occludens 1 (ZO-1) demonstrated that PEG 15-20 prevented significant changes in tight junction organization induced by bile acid exposure. Preliminary transepithelial electrical resistance-based studies examining structure-function correlates of polymer protection against bile acid damage were performed with a small library of PEG-based copolymers. Polymer properties associated with optimal protection against bile acid-induced barrier disruption were PEG-based compounds with a molecular weight greater than 10 kd and amphiphilicity. The data demonstrate that PEG-based copolymer architecture is an important determinant that confers protection against bile acid injury of intestinal epithelia.