bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent Advances in Vaccine Adjuvants for Systemic and Mucosal Administration
Authors: O’Hagan Derek T
Published: April 2011

Although vaccines produced by recombinant DNA technology are safer than traditional vaccines, which are based on attenuated or inactivated bacteria or viruses, they are often poorly immunogenic. Therefore, adjuvants are often required to enhance the immunogenicity of these vaccines. A number of adjuvants which are particulates of defined dimensions (< 5 μm) have been shown to be effective in enhancing the immunogenicity of weak antigens in animal models. Two novel adjuvants which possess significant potential for the development of new vaccines include an oil-in-water microemulsion (MF59) and polymeric microparticles. MF59 has been shown to be a potent and safe adjuvant in human subjects with several vaccines (for example HSV-2, HIV-1 and influenza virus). An MF59 adjuvanted influenza has been recommended for approval in Italy.

Microparticles prepared from the biodegradable polymers the poly(lactide-co-glycolides) (PLG) are currently undergoing extensive pre-clinical evaluation as vaccine adjuvants. Because of their controlled release characteristics, microparticles also possess considerable potential for the development of single dose vaccines. The development of single dose vaccines would offer significant advantages and would improve vaccination uptake rates in at risk populations, particularly in the developing world. In addition to systemic administration, microparticles have also also been shown to enhance the immunogenicity of vaccines when administered by mucosal routes. Therefore microparticles may allow the development of novel vaccines which can be administered by non-parenteral routes. Mucosal administration of vaccines would significantly improve patient compliance by allowing immunization to be achieved without the use of needles.

An alternative approach to the development of mucosally administered vaccines involves the production of genetically detoxified toxins. Heat labile enterotoxin (LT) from Escherichia coli and cholera toxin from Vibrio cholerae are two closely related bacterially produced toxins, which are the most potent adjuvants available. However, these molecules are too toxic to be used in the development of human vaccines. Nevertheless, these toxins have been modified by site-directed mutagenesis to produce molecules which are adjuvant active, but non-toxic. The most advanced of these molecules (LTK63), which has a single amino acid substitution in the enzymatically active subunit of LT, is active as an adjuvant, but non-toxic in pre-clinical models. The approach of genetically detoxifying bacterial toxins to produce novel adjuvants offers significant potential for the future development of mucosally administered vaccines.
Abstract
Authors: Murakami Teruo , Yoshioka Makiko , Yumoto Ryoko , Higashi Yutaka , Shigeki Sadayuki , Ikuta Yoshikazu , Yata Noboru
Published: April 2011

Topical delivery of tranilast (N-(3,4-dimethoxycinnamoyl)anthranic acid), an inhibitor of collagen synthesis and a therapeutic drug for keloid and hypertrophic scar, was examined, in rats, with oleic acid alone or a combination of oleic acid and propylene glycol as penetration enhancer. Evaluation was by measurement of the concentration of tranilast in plasma and in the dialysate from skin microdialysis.

When tranilast at a dose of 1.5 mg was applied topically as an ethanol solution containing 5% polyvinylpyrrolidone on a dorsal skin surface (2.25 cm2), the maximum concentration of tranilast in skin dialysate was approximately 2 μM. When 10 or 20% oleic acid was added to the same ethanol solution the maximum concentration of tranilast in the dialysate increased to 10–20 μM, and this value was further increased to 60 μM by the addition of a combination of oleic acid (10 or 20%) and propylene glycol (10%) to the solution. With the combination of oleic acid and propylene glycol the area under the plot of the concentration of tranilast in skin dialysate against time between 0 and 4 h (AUC0–4) was more than 400-fold that after intravenous administration. The transdermal bioavailability of tranilast as assessed by the AUC0–4 of tranilast in plasma, was 0.2% of the dose applied in the ethanol solution, 3–5% of that applied in the ethanol solution containing oleic acid, and 14–16% of that applied in the ethanol solution containing both oleic acid and propylene glycol.

These results suggest that the topical delivery of tranilast with an absorption enhancer such as a mixture of oleic acid and propylene glycol might be a more effective medication than oral administration of tranilast for the treatment of keloid and hypertrophic scar.
Effect of Ointment Bases on Topical and Transdermal Delivery of Salicylic Acid in Rats: Evaluation by Skin Microdialysis
Authors: Murakami Teruo , Yoshioka Makiko , Okamoto Ichiro , Yumoto Ryoko , Higashi Yutaka , Okahara Kayo , Yata Noboru
Published: April 2011

Microdialysis has been used to determine the concentration of salicylic acid in skin tissue and plasma periodically for 4 h to evaluate the effect of ointment bases on topical and transdermal delivery of salicylic acid. The ointment bases examined were solbase (water-soluble), poloid and white petrolatum (oleaginous), hydrophilic poloid (water in oil (w/o) type emulsion lacking water) and absorptive ointment (w/o-type emulsion containing water). The ointments (0.1 g) containing 25 μmol salicylic acid were applied for 2 h to the surface of rat skin (1 cm2) with (intact) or without the stratum corneum.

For intact skin, the extent of topical delivery from different ointments, evaluated by the area under the concentration-time curve (AUC) of salicylic acid in the skin tissue (AUCskin), increased in the order solbase. white petrolatum, poloid, hydrophilic poloid. absorptive ointment. The ratio of AUCskin (topical delivery) to the AUC of salicylic acid in plasma (AUCplasma, transdermal delivery) varied remarkably among the different bases, the greatest ratio being observed for absorptive ointment. When the ointments were applied to skin surface without stratum corneum, AUCskin for solbase was much higher (about 45 times that for intact skin), whereas only a small (two-fold) increase was observed for poloid and hydrophilic poloid and the increase was negligible for white petrolatum and absorptive ointment. For skin without the stratum corneum, the ratio AUCskin/AUCplasma for the different ointments was comparable, although the magnitudes of AUCskin and AUCplasma still varied substantially. The variance of AUC values arises as a result of the different rates of release of salicylic acid from the bases.

These results indicate that: the topical and transdermal delivery of salicylic acid in intact skin varies substantially among different ointment bases, and the greatest topical delivery is observed for absorptive ointment; use of absorptive ointment increases the retention of salicylic acid in the stratum corneum; and the stratum corneum functions strongly as a penetration barrier for solbase, moderately for poloid and hydrophilic poloid, and less for absorptive ointment and white petrolatum.
Abstract
Authors: Miyamura Mitsuhiko , Ono Masahide , Kyotani Shojiro , Nishioka Yutaka
Published: April 2011

Sho-saiko-to, one of the most widely used Chinese herbal preparations, has long been used for the treatment of chronic liver diseases. We have investigated its effect in retarding the process of liver fibrosis and accelerating liver regeneration, especially its effect on Ito cells that are thought to be deeply involved with liver fibrosis.

Sho-saiko-to extract and its active constituents were orally administered to rats with dimethy lnitrosamine-induced liver-injury. After treatment with sho-saiko-to extract hepatic function improved, histopathological results confirmed repair of liver tissue, and retinoid levels increased. On the other hand, when active constituents of sho-saiko-to extract were administered alone, liver retinoid levels remained low, implying that interaction among active constituents of the extract was suppressing Ito cell activation. When sho-saiko-to extract was administered to 70% hepatectomized normal and liver-injured rats, liver weight, the number of S-phase-cells and retinoid levels increased with time. However, these changes were different for normal and liver-injured rats, suggesting that the site of action of sho-saiko-to extract in regenerating liver is different for normal and liver-injured rats.

These results show that sho-saiko-to extract was useful for suppressing the activation of Ito cells.
The Effect of Dose on the Characterization of Aerodynamic Particle-size Distributions of Beclomethasone Dipropionate Metered-dose Inhalers
Authors: El-Araud Khalifa A , Clark Brian J , Kaahwa Carol , Anum Philip , Chrystyn Henry
Published: April 2011

The aerodynamic particle-size distribution for two doses of a Becloforte metered-dose inhaler (MDI) was measured by use of a twin-stage impinger (TSI), the new multi-stage (five-stage) liquid impinger (MSLI) and the Andersen cascade impactor (ACI) (n = 5 for each apparatus). The mean (s.d.) fine-particle doses measured by the three techniques for the Becloforte MDI were 40.3 (1.2), 45.7 (0.5) and 41.8 (0–4)% w/w, respectively; the median mass aerodynamic diameters (MMAD) measured using the MSLI and the ACI were 3.50 and 3.73 μm, respectively. The MSLI fine particle (< 6.8 μm) doses for 2, 5, 10, 20, 30 and 40 doses from Becloforte MDIs (n = 5 for each dose) were 49.7 (0.7), 52.9 (1.2), 45.3 (0.6), 45.5 (0.71), 45.9 (0.7) and 46.4 (0.7)% w/w, respectively. Values obtained using the ACI (< 5.8 μm) were 40.8 (1.0), 41.0 (0.8), 44.4 (0.5), 43.1 (0.4), 42.8 (0.5) and 40.4 (0.4)% w/w (n = 4). MMAD values measured with the MSLI were 3.39, 3.46, 3.75, 3.91, 4.15 and 4.45 μm, respectively; using the ACI they were 3.46, 3.54, 3.61, 3.66, 3.73 and 3.85 μm.

The results indicate that the measured aerodynamic particle-size distributions of beclomethasone dipropionate MDIs are affected by the dose dispensed and by the apparatus used for measurement.
Propylene Glycol Elicits Anxiolytic-like Responses to the Elevated Plus-maze in Male Mice
Authors: Lin Hui Qiang , Burden Peter M , Johnston Graham A R
Published: April 2011

Propylene glycol is a common solvent often contained in injectable solutions of anxiolytics of low water-solubility, such as diazepam (Valium) and pentobarbital (Nembutal). Several studies have shown that propylene glycol can have an inhibitory effect on the central nervous system. This study, using ethanol for comparison, further examined whether propylene glycol has anti-anxiety properties.

Use of the elevated plus-maze test with male mice revealed that propylene glycol at doses (27 or 41 mmol kg−1, i.p.) which did not affect general activity, increased the number of entries into open arms and of head dips over open arm edges, indicative of an anxiolytic effect. In parallel, ethanol (14 and 27 mmol kg−1, i.p.) caused an increase in the amount of time spent on open arms and number of entries into open arms, accompanied by reduction of returns into closed arms. These doses of ethanol had no significant effect on motor ability.

The results suggest that propylene glycol can act as an anxiolytic agent and that its anxiolytic potency is weaker than that of ethanol. In addition to previous warnings about the pharmacological effects of propylene glycol, the findings of this study alert investigators to the anxiolytic properties of the compound when it is employed as a solvent in anxiety or anxiety-related studies.
Renal Excretion of Rhodamine 123, a P-Glycoprotein Substrate, in Rats with Glycerol-induced Acute Renal Failure
Authors: Kunihara Masahiro , Nagai Junya , Murakami Teruo , Takano Mikihisa
Published: April 2011

To clarify renal handling of rhodamine 123, a substrate for P-glycoprotein, in normal and diseased states, in-vivo clearance studies were performed with normal rats and rats with glycerol-induced acute renal failure.

For normal rats the excretion ratio of unbound rhodamine 123-to-inulin was 3.25, indicating the presence of the renal tubular secretion of rhodamine 123. Co-administration of cyclosporin, a P-glycoprotein inhibitor, significantly reduced tubular secretion of rhodamine 123. Administration of glycerol induced both an increase in blood urea nitrogen and a reduction in the glomerular filtration rate, confirming the induction of acute renal failure. Total plasma, renal, and tubular secretory clearances of rhodamine 123 were significantly lower for rats with acute renal failure than for control rats. There was no difference between the ATP content of the renal cortex in control rats and those with acute renal failure. In addition to the decrease in renal clearance, a decrease in the biliary clearance of rhodamine 123 was also observed in rats with acute renal failure.

These results imply that rhodamine 123 is secreted via P-glycoprotein in renal tubules and that the renal secretory clearance of rhodamine 123 was reduced after acute renal failure, probably because of impairment of P-glycoprotein.
Baicalin and Baicalein, Constituents of an Important Medicinal Plant, Inhibit Intracellular Ca2+ Elevation by Reducing Phospholipase C Activity in C6 Rat Glioma Cells
Authors: Kyo Reiki , Nakahata Norimichi , Sakakibara Iwao , Kubo Masayoshi , Ohizumi Yasushi
Published: April 2011

Glial cells have a role in maintaining the function of neural cells. This study was undertaken to clarify the effects of baicalin and baicalein, flavonoids isolated from an important medicinal plant Scutellariae Radix (the root of Scutellaria baicalensis Georgi), on glial cell function using C6 rat glioma cells.

Baicalin and baicalein caused concentration-dependent inhibition of a histamine-induced increase in intracellular Ca2+ concentrations ([Ca2+]i). The potency of baicalein was significantly greater than that of baicalin. The noradrenaline- and carbachol-induced increase in [Ca2+]i was also inhibited by baicalein and both drugs inhibited histamine-induced accumulation of total [3H]inositol phosphates, consistent with their inhibition of the increase in [Ca2+]i.

These results suggest that baicalin and baicalein inhibit [Ca2+]i elevation by reducing phospholipase C activity. The inhibitory effects of baicalin and baicalein on [Ca2+]i elevation might be important in the interpretation of their pharmacological action on glial cells, such as inhibition of Ca2+-required enzyme phospholipase A2.
Characterization of Amorphous Ursodeoxycholic Acid Prepared by Spray-drying
Authors: Ueno Yasuhiko , Yonemochi Etsuo , Tozuka Yuichi , Yamamura Shigeo , Oguchi Toshio , Yamamoto Keiji
Published: April 2011

The objectives of this study were to characterize the amorphous state of ursodeoxycholic acid (UDCA) samples prepared by spray-drying, and to demonstrate the applicability of thermal and water-vapour-adsorption techniques for studying the material.

Amorphous UDCA was prepared by spray-drying a solution of the compound in a mixture of ethanol and dichloromethane. The amorphous material was characterized by powder X-ray diffraction, infrared (IR) spectroscopy, isothermal microcalorimetry, differential scanning calorimetry (DSC) and water-vapour adsorption. When the inlet-air temperature of the spray drier was increased beyond 140°C, the intensity of X-ray diffraction peaks from crystalline UDCA decreased and the IR bands in the hydroxyl-stretching and carboxyl-stretching regions changed. Dissolution of intact and spray-dried samples of UDCA prepared at 60 and 100°C was an endothermic process but the dissolution became exothermic with increasing inlet-air temperature. UDCA samples differing in crystallinity were obtained, depending on the inlet-air temperature. A good correlation was obtained between the heat of solution and the heat of crystallization determined from DSC peak area. A good correlation was also obtained between the heat of solution and the crystallinity determined by Ruland’s method from X-ray diffraction patterns. The amount of water vapour adsorbed on UDCA samples increased with increasing inlet-air temperature, indicating hydrogen bonding between water molecules and the hydroxyl groups or the carboxyl groups of amorphous UDCA.

These results indicate that measurement of adsorption of water vapour and thermal analysis can both be used to evaluate the crystallinity of solid substances.
Enhanced Absorption of Calcium after Oral Administration of Maltitol in the Rat Intestine
Authors: Fukahori Masahiro , Sakurai Hidetomo , Akatsu Sakae , Negishi Munehiro , Sato Hiroshi , Goda Toshinao , Takase Sachiko
Published: April 2011

The enhancing effects of maltitol (α-D-glucopyranosyl-1,4-sorbitol) on absorption of calcium by the rat intestine have been studied by use of [45Ca]CaCl2 in-vivo.

After intragastric administration of [45Ca]CaCl2 solution with maltitol, plasma 45Ca concentration remained at the maximum level for more than 80 min, whereas for animals given [45Ca]CaCl2 solution without maltitol, plasma 45Ca concentration declined sharply after the peak. Determination of 45Ca radioactivity remaining in the various segments of the gastrointestinal tract revealed that administration of maltitol elicited slower gastric emptying and slower intestinal transit, resulting in extensive 45Ca distribution along the small intestine throughout the experimental period. The luminal contents of the small intestine were significantly higher in rats given maltitol than in the control group.

These results suggest that the enhancing action of maltitol on intestinal calcium absorption could be attributed to reduced gastrointestinal calcium transit and increased luminal fluid content, presumably because of the osmotic activity of maltitol; this would not only accelerate the dissolution of calcium into the increased luminal contents, but also enable a larger area of the small intestine to absorb calcium for a longer period of time.
α-Adrenoceptor Interaction of Tetrandrine and Isotetrandrine in the Rat: Functional and Binding Assays
Authors: Catret M , Anselmi E , Ivorra M D , Elorriaga M , Tur R , D’OcÓn M P
Published: April 2011

The action of 1S,1′S-tetrandrine, a bisbenzyltetrahydroisoquinoline alkaloid, on α1-adrenoceptors has been compared with that of its isomer 1R,1′S-isotetrandrine. The work includes binding assays to analyse the affinity of these products for the [3H]prazosin binding site of rat cerebral cortical membranes and functional studies on rat isolated aorta to examine the effects of both alkaloids on intracellular calcium processes related or not to α-adrenoceptor activation.

A radioligand receptor-binding study showed that both compounds interacted with the α1-adrenoceptors displacing [3H]prazosin from the specific binding site. The Ki values (inhibition constants) were 0.69±0.12 and 1.6±0.4 μM for tetrandrine and isotetrandrine, respectively. The functional studies showed that both alkaloids concentration-dependently inhibited noradrenaline-induced contraction in Ca2+-free solution (IC50 values, i.e. the concentrations needed to induce 50% inhibition, were 252.8 and 174.9 μM for tetrandrine and isotetrandrine, respectively), the spontaneous contractile response elicited by extracellular calcium after depletion of noradrenaline-sensitive intracellular stores (increase in resting tone; IC50 values 11.6 and 19.6 μM for tetrandrine and isotetrandrine, respectively) and the refilling of intracellular Ca2+ stores sensitive to noradrenaline (IC50 values 7.4 and 14.9 μM for tetrandrine and isotetrandrine, respectively).

The results show that tetrandrine and isotetrandrine interact with α1-adrenoceptors by displacing the [3H]prazosin binding site and that both compounds inhibit mainly the Ca2+-dependent process and have less action on α1-adrenoceptors. Tetrandrine is more potent than isotetrandrine.
Protein Kinase Inhibitors Attenuate Cardiac Swelling-induced Amino Acid Release in the Rat
Authors: Song D , O’Regan M H , Phillis J W
Published: April 2011

Rat Langendorff heart preparations have been used to study the efflux of cardiac amino acids into coronary artery perfusates during brief (5-min) periods of exposure to hyposmotic stress (70 mM NaCl). Coronary flow rates, heart rates and intra-aortic pressures were recorded. Amino acid levels were measured by high-performance liquid chromatography.

Hyposmotic stress caused marked percentage increases in taurine, glutamate and aspartate levels in the coronary perfusate, with smaller increases in phosphoethanolamine, glycine and alanine and non-significant increases in serine and glutamine. Amino acid levels declined during reperfusion with isosmotic Krebs-Henseleit bicarbonate buffer. Inhibition of protein kinase C with chelerythrine chloride (5 μM) depressed the osmotically-induced release of aspartate, glutamate, taurine and glycine. The protein tyrosine kinase inhibitor, genistein, reduced the anisosmotic efflux of aspartate, glutamate, taurine and phosphoethanolamine. Lavendustin A, another inhibitor of tyrosine kinase, depressed the osmotically evoked release of aspartate, glutamate and taurine.

These studies demonstrate the involvement of protein kinase C and tyrosine kinases in the efflux of amino acids from the osmotically challenged rat heart and imply that these enzymes are involved in the mechanisms responsible for volume regulation by cardiac cells.
Pharmacological Antagonism of Anchietia salutaris Extracts on the Contraction Induced by Prostaglandin D2 and U466 19 in Guinea-pig Lung Parenchymal Strips
Authors: Gambero Alessandra , Gomes José Carlos
Published: April 2011

Anchietia salutaris tea is traditionally used in Brazil to treat allergies, suggesting it contains compounds with antagonistic activity on the allergic mediators. We have evaluated extracts and semi-purified fractions of Anchietia salutaris as a source of compounds having this type of antagonism on the contraction induced in guinea-pig lung parenchymal strips and on platelet aggregation and shape change.

After 10 min pre-incubation dichloromethane extracts containing 30 or 100 μg mL−1 inhibited the contraction induced by prostaglandin D2 (PGD2) in guinea-pig lung parenchymal strips with dose ratios (DR) of 0.76±0.14 and 0.93±0.19, respectively; the amount of inhibition depended both on the concentration and on the time of preincubation (DR after 30 min pre-incubation was 1.21±0.51). The dichloromethane extract and its semi-purified fractions also inhibited the contractions induced by U46619, a more potent, stable, synthetic agonist of thromboxane A2 (TxA2) prostanoid (TP) receptors, the receptors acted upon by PGD2 to produce lung contractions. The dichloromethane extract did not inhibit the lung parenchymal contractions induced by histamine, leukotriene D4 (LTD4) or platelet-activating factor (PAF). Platelet aggregation induced by U46619, adenosine 5′-diphosphate (ADP) or PAF was not inhibited by the dichloromethane extract. Indeed, the extract potentiated platelet aggregation induced by low concentrations of these agonists and also potentiated the shape change induced by U46619.

These results imply that the dichloromethane extract of Anchietia salutaris and its semi-purified fractions contain an active principle that competitively inhibits TxA2 TP receptors, the stimulation of which causes lung parenchymal contraction. The inhibition seems to be selective for this receptor subtype, because the extract fails to inhibit platelet aggregation or shape change. This provides additional support of earlier reports suggesting the occurrence of TP receptor subtypes.
Rapid Killing of Mycobacterium terrae by N-Chlorotaurine in the Presence of Ammonium is Caused by the Reaction Product Monochloramine
Authors: Nagl Markus , Gottardi Waldemar
Published: April 2011

We have studied the activity of the weak endogenous oxidant N-chlorotaurine against Mycobacterium terrae.

The study revealed slow killing of more than 2 h duration by 1% (55 mM) N-chlorotaurine. In the presence of ammonium chloride, however, killing times decreased to a few minutes, even by 0.1% N-chlorotaurine.

This phenomenon is explained by formation of the lipophilic and therefore more bactericidal monochloramine as a result of transhalogenation of ammonia by N-chlorotaurine.
Enantioselectivity of Some 1-(Benzofuran-2-y1)1-(1-H-imidazol-1-yl) Alkanes as Inhibitors of P450Arom
Authors: Khodarahmi G Ali , Smith H John , Nicholls Paul J , Ahmadi Masoud
Published: April 2011

The low stereospecificity of the enantiomers of 1-[(benzofuran-2-yl)-4-chlorophenyl-methyl]imidazole (6, R = H, R’ = 4′-Cl) and the corresponding 4-fluoro compound as inhibitors of aromatase (P450Arom) has been explored using 1-(5,7-dichlorobenzofuran-2-yl)-1-(1H-imidaz-1-yl)ethane (7, R1=R2 = Cl, R = CH3), -propane (7, R1=R2 = Cl, R = C2H5), and the corresponding 5,7-dibromo compounds resolved as their dibenzoyl-D (or -L) tartrates.

Low enantioselectivity ratios of 4.8 (5,7-diCl) and 12.6 (5,7-diBr) were shown for the ethanes. The values for the corresponding propanes were 8.3 and 5.2, respectively, and for these compounds the stereoselectivity was reversed.
The Biological Activity of Selected Cyclic Dipeptides
Authors: Milne P J , Hunt A L , Rostoll K , Van Der Walt J J , Graz C J M
Published: April 2011

Cyclic dipeptides are widely used as models for larger peptides because of their simplicity and limited conformational freedom. Some cyclic dipeptides have been shown to be antiviral, antibiotic and anti-tumour. The aim of this study was to determine the biological activity of four cyclic dipeptides synthesized in this laboratory: cyclo(L-phenylalanyl-L-prolyl), cyclo(L-tyrosyl-L-prolyl), cyclo(L-tryptophanyl-L-prolyl) and cyclo(L-tryptophanyl-L-tryptophanyl).

The enhancement or inhibition of calcium channels in ventricular myocytes from rats and delayed-rectifier potassium channels in ventricular myocytes from guinea-pigs were determined by use of the whole-cell patch-clamp technique. The induction of differentiation in HT-29 cells was assessed by assaying for an increase in the expression of alkaline phosphatase. Antibiotic properties against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilus and Streptococcus sp. were determined by use of the Kirby—Bauer disc-diffusion assay. Results from these assays indicate that the cyclic dipeptides have biological activity in both prokaryotes and eukaryotes. Three of the dipeptides block cation channels in ventricular myocytes and all increase the expression of alkaline phosphatase. All the dipeptides have concentration-dependent antibacterial properties.

These results suggest that with increased solubility the cyclic dipeptides might have potential as muscle relaxants, anti-tumour compounds and antibiotics.
Selection and Use of Crystallization Inhibitors for Matrix-type Transdermal Drug-delivery Systems Containing Sex Steroids
Authors: Lipp Ralph
Published: April 2011

The purpose of this study was to stabilize transdermal drug-delivery systems (TDDS) highly loaded with sex steroids against recrystallization of drugs during storage. To facilitate the selection of potential crystallization inhibitors a drug-excipient interaction test was also established.

Analysis of the thermal behaviour of 1:1 steroid-excipient mixtures by differential scanning calorimetry (DSC) revealed that oestradiol and gestodene interact strongly with silicone dioxide and povidones, e.g. povidone K12. The addition of povidone K12 to polyacrylate-based matrix TDDS containing either 3% oestradiol or 2% gestodene resulted in stable systems which did not recrystallize during storage at 25°C for more than 5 years. Significant recrystallization was, on the other hand, observed in non-stabilized reference patches even after 1 to 2 months storage.

The DSC screening model proved very effective for selection of inhibitors of the crystallization of sex steroids in matrix TDDS. The crystallization inhibitor approach is a highly versatile stabilization tool for matrix patches containing high concentrations of sex steroids.
Stereochemical Studies of the Isomerization of Novel 2-Alkyl-9-phenyl-2,3,4,4a- and 2,3,4,9-tetrahy dro-1H-indeno [2,1 -c]pyridines
Authors: Upton Christopher , Jaffar Mohammed
Published: April 2011

The published synthetic route to the antihistaminic tetrahydroindeno[2,1-c]pyridines (phenindamines) relies on catalytic reduction of the precursor dihydroindenopyridines. This reduction gives mixtures of 9,9a- and 4a,9a-enes and the clinically active 4a,9a isomer has to be isolated by recrystallization of an appropriate salt. The structure of the product recovered depends on the anion used to isolate the proton salt and appears to be arbitrary.

To rationalize this outcome a series of novel N-2 alkylated tetrahydroindeno[2,1-c]pyridines and their diene precursors has been synthesized from accessible piperidines. The structures and geometry of the piperidines and the dihydro- and tetrahydroindenopyridines have been determined by 1H and 13C NMR. An unusual feature of the proton spectra of the piperidines is the resonance of the axial protons at lower field than their equatorial counterparts. By controlling the reaction conditions for the reduction of the dihydroindenopyridines to their tetrahydro derivatives the kinetic or thermodynamic product can be selected as required.

A predictable outcome for the reductions investigated was achieved and is generally applicable.
Enterohepatic Cycling and Pharmacokinetics of Oestradiol in Postmenopausal Women
Authors: Vree Tom B , Timmer Cees J
Published: April 2011

The pharmacokinetics and enterohepatic cycling of oestradiol have been studied after three oral, single-dose administrations of equimolar doses of oestradiol alone, oestradiol plus desogestrel and oestradiol valerate, in a 3-way cross-over mode in 18 healthy postmenopausal women.

Oestradiol was readily absorbed and metabolized to oestrone, which reached much higher serum concentrations (140pgmL−1) than its parent compound (35pgmL−1). All three formulations had the same kinetic profile and were bioequivalent on testing. Noticeable first and second absorption phases were apparent from the oestradiol and oestrone serum concentration-time curves for all oestradiol formulations. The mean serum concentration-time curves of the metabolite oestrone (corrected for endogenous oestrone) showed a second maximum at approximately 25 h. By means of line feathering, serum concentration-time curves were constructed which belonged to the first, second and third phases of absorption. The maximum serum concentration, Cmax, of the second absorption or recirculation of oestrone was 20% that of the first, and the Cmax of the third circulation was 50% that of the second. The areas under the serum-concentration-time curves (AUC) for the second and third recirculations were similar—each comprised 12–13% of the total AUC. The oral clearance values of the recirculations were constant (590Lh−1).

Enterohepatic recirculation of endogenous compounds is aimed at maintaining a steady-state serum concentration for immediate use and hydrolysis in the target organs. It is concluded that exogenously added oestradiol and its metabolites follow the recirculation pathways of the endogenous oestrogen pool.
Relative Dispersions of Intra-albumin Transit Times across Rat and Elasmobranch Perfused Livers, and Implications for Intra- and Inter-species Scaling of Hepatic Clearance using Microsomal Data
Authors: Roberts Michael S , Ballinger Linsay N , Weiss Michael
Published: April 2011

It is recognized that vascular dispersion in the liver is a determinant of high first-pass extraction of solutes by that organ. Such dispersion is also required for translation of in-vitro microsomal activity into in-vivo predictions of hepatic extraction for any solute. We therefore investigated the relative dispersion of albumin transit times (CV2) in the livers of adult and weanling rats and in elasmobranch livers.

The mean and normalized variance of the hepatic transit time distribution of albumin was estimated using parametric non-linear regression (with a correction for catheter influence) after an impulse (bolus) input of labelled albumin into a single-pass liver perfusion. The mean±s.e. of CV2 for albumin determined in each of the liver groups were 0·85 ± 0·20 (n = 12), 1·48 ± 0·33 (n = 7) and 0·90 ± 0·18 (n = 4) for the livers of adult and weanling rats and elasmobranch livers, respectively.

These CV2 are comparable with that reported previously for the dog and suggest that the CV2 of the liver is of a similar order of magnitude irrespective of the age and morphological development of the species. It might, therefore, be justified, in the absence of other information, to predict the hepatic clearances and availabilities of highly extracted solutes by scaling within and between species livers using hepatic elimination models such as the dispersion model with a CV2 of approximately unity.
Time-dependent Effects of Klebsiella pneumoniae Endotoxin on Hepatic Drug-metabolizing Enzyme Activity in Rats
Authors: Nadai Masayuki , Sekido Tohru , Matsuda Izumi , Li Wang , Kitaichi Kiyoyuki , Itoh Akio , Nabeshima Toshitaka , Hasegawa Takaaki
Published: April 2011

The time-dependent effects of Klebsiella pneumoniae endotoxin on hepatic cytochrome P450-dependent drug-metabolizing capacity (cytochrome P450 and b5 content, activity of aminopyrine N-demethylase, p-nitroanisole O-demethylase, aniline hydroxylase and benzphetamine N-demethylase) and on the pharmacokinetics of antipyrine have been determined in rats. Measurement of enzyme activity and antipyrine (after intravenous injection of 20 mgkg−1) were performed 2, 24 and 96 h after a single intraperitoneal injection of endotoxin (1 mgkg−1) and after repeated doses (once daily for 4 days). The contribution of tumour necrosis factor α (TNFα) to the endotoxin-induced changes was also examined in rats pretreated with granulocyte colony-stimulating factor (G-CSF).

The systemic clearance of antipyrine and the activity of hepatic cytochrome P450-dependent drug-metabolizing enzymes were dramatically reduced 24 h after a single injection of endotoxin, but had returned to control levels by 96 h. The magnitudes of these decreases in these measurements after repeated doses of endotoxin were similar to those seen 24 h after the single dose. The systemic clearance of antipyrine correlated significantly with cytochrome P450 content and aminopyrine N-demethylase activity. In histopathological experiments, moderate hypertrophy of Kupffer cells was observed, with no evidence of severe liver-tissue damage. G-CSF pretreatment suppressed the increased plasma concentrations of TNFα produced 2 h after single endotoxin injection, but did not eliminate the endotoxin-induced decrease in the systemic clearance of antipyrine, suggesting that TNFα is not the sole component responsible for the reduction of cytochrome P450-mediated drug-metabolizing enzyme activity.

These results provide evidence that a single intraperitoneal injection of 1·0 mgkg−1  K. pneumoniae endotoxin in rats reduces hepatic P450 and b5 levels, and reduces the activity of various cytochrome P450-mediated drug-metabolizing enzymes without causing severe liver-tissue damage. This suggests that the effect of endotoxin on hepatic cytochrome P450-mediated drug-metabolizing isozymes is non-selective.
Endothelium-dependent Relaxation in Response to Ethanol Porcine Isolated Pulmonary Artery
Authors: Lawrence Rebecca N , Dunn William R , Wilson Vince G
Published: April 2011

Many drugs cannot be dissolved in distilled water and so other solvents such as ethanol, dimethylsulphoxide and methanol are used. Because very little is known about the direct effects of these three solvents on the cardiovascular system, we have examined their effects on isolated pulmonary and coronary arteries from the pig.

Increasing concentrations of ethanol, dimethylsulphoxide and methanol induced relaxation in porcine pulmonary (at 1·2% v/v, 59·9±9·0% (n = 9), 55·9±9·0% (n = 6) and 12·3±6·4% (n = 8), respectively, of U46619-induced tone) and coronary arteries (at 1·2% v/v, 69·9±7·1% (n = 10), 78·9±6·1% (n = 7) and 12·9±8·2% (n = 6) respectively, of U46619-induced tone). In the pulmonary arteries the relaxation in response to ethanol was found to be endothelium-dependent whereas the responses to dimethylsulphoxide and methanol were unaffected by removal of the endothelium. In the coronary arteries the relaxation to all three solvents was independent of the presence of the endothelium. Comparison of the sensitivity of the tissues to the solvents showed that ethanol and dimethylsulphoxide produced comparative responses in both the pulmonary and coronary arteries, whereas methanol was much less potent. The endothelium-dependent response to ethanol in the porcine pulmonary artery (maximum response, Emax, 67·1±9·3% of U46619-induced tone, n = 7) was attenuated by the cyclooxygenase inhibitor, flurbiprofen (Emax 31·9±12·0%, n = 7), the nitric oxide synthase inhibitor, L-NAME (NG-nitro-L-arginine methyl ester; Emax 23·5±10·2%, n = 7)) and the combination of both inhibitors (Emax 18·3±7·8%, n = 7). The residual relaxatory response to ethanol was abolished, and converted into a contractile response, both by removal of the endothelium (at 1·7% v/v ethanol 27·3±11·5% of U46619-induced tone, n = 7) and by the addition of a low concentration of KCl (49·9±10·3%, n = 6), suggesting the release of a non-prostanoid, non-nitric oxide factor from the endothelium. This response, however, was not attenuated by the cannabinoid receptor-antagonist SR141716A (N-(piperidin-1-yl)-5-(4-chloro-phenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide HCl; 52·5±4·3% relaxation, n = 8), suggesting that the factor released in this preparation by ethanol is not a cannabinoid.

The results of this study indicate that many solvents commonly used in pharmacological experiments have pronounced vasoactive properties. Methanol might be the vehicle of choice, because it was the least active solvent, whereas high concentrations of ethanol might influence vascular function at both the level of the smooth muscle and the endothelium, with the action on the endothelium involving the release of endothelium-derived relaxing factors.
Influence of Trimebutine on Inflammation- and Stress-induced Hyperalgesia to Rectal Distension in Rats
Authors: Lacheze C , Coelho A-M , Fioramonti J , Buéno L
Published: April 2011

The effects of trimebutine and its major metabolite, N-desmethyltrimebutine on inflammation- and stress-induced rectal hyperalgesia have been evaluated in rats fitted with electrodes implanted in the longitudinal striated muscle of the abdomen.

Intermittent rectal distension was performed before and 3 days after induction of rectal inflammation by local infusion of trinitrobenzenesulphonic acid (in ethanol). Stress consisted of 2 h partial restraint and rectal distension was performed before and 30min after the end of the partial restraint session. The animals were treated intraperitoneally with trimebutine or desmethyltrimebutine (5, 10 or 20mgkg−1) or vehicle 15min before rectal distension. Naloxone (1mgkg−1) or saline was injected subcutaneously before trimebutine and desmethyltrimebutine. Before treatment trimebutine at the highest dose (20 mgkg−1) reduced the abdominal response to rectal distension for the highest volume of distension (1·6mL) whereas desmethyltrimebutine was inactive. After rectocolitis the abdominal response to rectal distension was enhanced and trimebutine at 5mgkg−1 reduced and at 10mgkg−1 suppressed inflammation-induced hyperalgesia, an effect reversed by naloxone. Desmethyltrimebutine was inactive. Stress-induced hypersensitivity was attenuated or suppressed, or both, by trimebutine and desmethyltrimebutine at doses of 5, 10 or 20mgkg−1; greater efficacy was observed for desmethyltrimebutine and the effects were not reversed by naloxone.

It was concluded that trimebutine and desmethyltrimebutine are active against inflammation- and stress-induced rectal hyperalgesia but act differently. The effect of trimebutine on inflammation-induced hyperalgesia is mediated through opioid receptors.
Influence of Twinline, an Elemental Diet, on the Generation of Nitric Oxide and Reactive-oxygen Intermediates from Mouse Peritoneal Macrophages and Polymorphonuclear Leukocytes
Authors: Ueta Eisaku , Yoneda Kazunori , Yamamoto Tetsuya , Osaki Tokio
Published: April 2011

The influence of Twinline (SNN-6010), an elemental diet containing medium-chain triglycerides, on the generation of nitric oxide (NO) and superoxide (O2−) has been examined in mouse peritoneal macrophages and polymorphonuclear leukocytes (PMN).

When PMN and peritoneal macrophages obtained from untreated mice were cultured in medium containing 0·1% and 1% (v/v) Twinline for 48h and stimulated with phorbol myristate acetate or N-formyl-methionyl-leucyl-phenylalanine, their chemiluminescence and O2− generation were strongly suppressed, as was NO generation from peritoneal macrophages. PMN and peritoneal macrophages obtained from mice fed Twinline for 30 days generated much smaller amounts of O2− and NO compared with PMN and peritoneal macrophages from control mice. In conjunction with this suppressed NO generation, inducible NO synthase and its mRNA expression in peritoneal macrophages were suppressed by Twinline both in-vivo and ex-vivo. Although phagocytosis of PMN and peritoneal macrophages was not suppressed by Twinline; their candida-killing activity was markedly suppressed.

These results indicate that Twinline suppresses the host-defence function of PMN and peritoneal macrophages by down-regulating their generation of reactive-oxygen intermediates and NO.
Aqueous Stability of SB 210661: Kinetics and Primary Degradation Mechanisms of an N-Hydroxyurea-containing 5-Lipoxygenase Inhibitor
Authors: McLoughlin Martin , Kearney Albert S , Palepu Nagesh R
Published: April 2011

SB 210661, (S)-N-hydroxy-N-[2,3-dihydro-6-(2,6-difluorophenylmethoxy)-3-benzofuranyl]urea, is a potent and selective inhibitor of 5-lipoxygenase. Its aqueous stability was primarily evaluated to support development of analytical methods and formulations. The results also add to the growing database on the stability of N-hydroxyurea compounds.

Comparison of the stability of SB 210661 with that of two other N-hydroxyurea-containing compounds, zileuton and Abbott-79175, supported a common primary degradative pathway at pH > 5 and different degradative pathways at pH < 5. The pathway at pH > 5 is consistent with the hydrolysis of the N-hydroxyurea group, whereas for SB 210661, the pathway at pH < 5 is consistent with specific acid-catalysed nucleophilic displacement of the N-hydroxyurea group by water.
Intestinal Absorption of Stable Cyclic Dipeptides by the Oligopeptide Transporter in Rat
Authors: Mizuma Takashi , Masubuchi Satoshi , Awazu Shoji
Published: April 2011

Intestinal absorption of four cyclic dipeptides was studied in the everted small intestine of the rat.

Cyclic seryltyrosine (cyclo(Ser-Tyr)) was stable enough to be transported whereas linear seryltyrosine was not. The absorption clearance of cyclo(Ser-Tyr) was concentration-dependent, and for cyclo(Ser-Tyr) at 125 μM decreased in the presence of glycylsarcosine (10 mM) or cephalexin (10 mM), which were reported to be absorbed by oligopeptide transporter. The absorption clearance was also reduced at 4°C and in the presence of 1 mM dinitrophenol. Kinetic analysis of cyclo(Ser-Tyr) absorption showed that Km and Vmax were 19.8 μM and 0.295 nmol min−1 cm−1, respectively. It was also suggested that cyclic aspartylphenylalanine and cyclic histidylphenylalanine were absorbed by oligopeptide transporters, but cyclic histidylproline was not. The absorption clearance of cyclo(Ser-Tyr) in the control was much higher than the value of the correlation line representing a plot of passive transport (which was obtained from the absorption clearance of cyclic peptides in the presence of glycylsarcosine (10 mM)) against hydrophobicity (oil-water partition coefficient).

These results indicate that cyclo(Ser-Tyr) is absorbed by the oligopeptide transporter.
Effect of Sequence of Administration on the Pharmacokinetic In,t. eraction between the Anticholinergic n Drug Biperiden and ['H]Quinuclidinyl Benzylate or [5H]N-Methylscopolamine in Rats
Authors: Ishizaki Junko , Yokogawa Koichi , Nakashima Emi , Takayasu Tatsunori , Ohshima Tohru , Ichimura Fujio
Published: April 2011

In rats the pharmacokinetic interactions between the anticholinergic drug biperiden and [3H]quinuclidinyl benzylate ([3H]QNB) or [3H]N-methylscopolamine ([3H]NMS) is affected by the sequence in which the drugs are administered.

Drug concentrations in various tissues were determined after intravenous administration of [3H]QNB or [3H]NMS (325 ng kg−1). Biperiden (6.4 mg kg−1) was administered either 5 min before, concomitantly with or 20 min after injection of [3H]QNB or [3H]NMS. When biperiden was administered concomitantly with or before [3H]QNB, distribution of [3H]QNB among the regions of the brain and other tissues was reduced; at 4 h the ratio of the distribution of [3H]QNB for experimental animals to that for control animals ranged from 0.15 to 0.9. When biperiden was administered after [3H]QNB, the distribution of [3H]QNB in the brain and other tissues was significantly higher than for the other two treatments (P < 0.01). However, for [3H]NMS the sequence of administration had no effect on the distribution of the drug in the brain and other tissues except for the kidney. In-vitro, in crude synaptosomal membranes, the amount of [3H]QNB at 2 h relative to the control concentration at equilibrium was 87% when biperiden was added before [3H]QNB and 56% when biperiden was added after [3H]QNB. In both instances the concentration of [3H]NMS reached equilibrium within 30 min.

These findings suggest that the difference between the rate constant of association and dissociation at the possible site of action gives rise to the effect of the sequence of administration on the pharmacokinetic interaction.
Sodium Nitroprusside Enhances Contractions of the Guinea-pig Isolated Vas Deferens
Authors: Ventura Sabatino , Hoyle Charles H V , Burnstock Geoffrey
Published: April 2011

The effects of sodium nitroprusside on the electrical and mechanical properties of the smooth muscle of the guinea-pig vas deferens, and its responses to transmitter substances, have been investigated by use of the sucrose-gap technique.

Isolated longitudinal segments of guinea-pig vas deferens contracted in response to electrical field stimulation (100 V, 0.04–0.1 ms, 1–5 Hz, 10 s train every 60 s) and application of ATP (1 mM) or noradrenaline (10 μM). Sodium nitroprusside (0.1 mM) did not affect resting tension but did enhance contractions evoked by electric-field stimulation but not by ATP or noradrenaline. The sodium nitroprusside-induced enhancement was unaffected by the nitric oxide synthase inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME) (0.1 mM). Conversely, electrically evoked contractions were unaffected by the nitric oxide precursor L-arginine (1 mM) or the nitric oxide donor S-nitroso-N-acetyl-DL-penicillamine (SNAP) (0.1 mM). The amplitudes of electrically evoked excitatory junction potentials (EJPs) were not affected by application of sodium nitroprusside, although it caused a small depolarization of 0.7 ± 0.3 mV. Similarly, the depolarization caused by exogenous application of ATP or noradrenaline was unaffected by the presence of sodium nitroprusside. L-NAME, L-arginine and SNAP did not affect EJP amplitude or baseline membrane potential.

It is concluded that sodium nitroprusside enhances electrically evoked contractions of the guinea-pig vas deferens by reducing the threshold voltage for action potential firing in smooth-muscle cells.