bluuebunny/crossref_metadata_2025 huggingface dataset:
Further Studies on the Ex-vivo Effects of Procarbazine and Monomethylhydrazine on Rat Semicarbazide-sensitive Amine Oxidase and Monoamine Oxidase Activities
Authors: Holt Andrew , Callingham Brian A
Published: April 2011

Following administration of the anticancer agent, procarbazine, or one of its metabolites, monomethylhydrazine, to rats, activities of monoamine oxidases A and B (MAO A and MAO B) and of semicarbazidesensitive amine oxidase (SSAO) were measured ex-vivo.

Both compounds were found to be potent inhibitors of SSAO in tissue homogenates, exhibiting ID50 values in most tissues of approximately 8 mgkg−1 (procarbazine) and 0.08 mg kg−1 (monomethylhydrazine). Concurrent dose-dependent inhibition of MAO activities did not occur. However, in liver, potentiation of MAO B activity, to 140% of that in controls, was apparent following monomethyl-hydrazine and this effect was independent of the drug dose. Both compounds produced a dose-dependent potentiation of MAO A in brown adipose tissue, the elevation being more pronounced following monomethylhydrazine, with activity rising to 350% of that in control homogenates. In a parallel in-vitro study, monomethylhydrazine was without effect on MAO A in brown adipose tissue homogenates. By perfusing the SSAO substrate, benzylamine, through the isolated mesenteric arterial bed of the rat, it was found that pretreatment of animals with procarbazine or monomethylhydrazine reduced metabolism of this amine by a similar degree as had been determined ex-vivo in blood vessel homogenates.

The results presented suggest that these compounds would be suitable for use as selective inhibitors in pharmacological examinations of SSAO function in isolated tissues and organs.
Analysis of the Mechanisms Underlying the Contractile Response Induced by the Hydroalcoholic Extract of Phyllanthus urinaria in the Guinea-pig Urinary Bladder In-vitro
Authors: Dias Marcos A , Campos Alexandre H , Filho Valdir Cechinel , Yunes Rosendo A , Calixto Joao B
Published: April 2011

The hydroalcoholic extract of Phyllanthus urinaria (Euphorbiaceae), substance P and substance P methyl ester all caused graded contractions in the guinea-pig urinary bladder. Responses to hydroalcoholic extract and substance P were markedly inhibited in calcium-free Krebs solution, this effect being reversed by reintroduction of calcium in the medium.

The contraction in response to hydroalcoholic extract was unaffected by atropine, propranolol, prazosin, yohimbine, tetrodotoxin, w-conotoxin, nicardipine, HOE 140, guanethidine, staurosporine, phorbol ester or indomethacin, excluding the involvement of nervous mediated responses, or action via cholinergic, adrenergic, kinins, cyclo-oxygenase metabolites, protein kinase C or activation of L or N-type calcium channels. The selective NK1 tachykinin antagonist (FK 888), but not NK2 (SR 48968) antagonized substance P-induced contraction, but both drugs failed to effect Phyllanthus urinaria-induced contraction. Prolonged desensitization of guinea pig urinary bladder with capsaicin (10 μM) or preincubation of guinea-pig urinary bladder with capsazepine did not affect contraction caused by hydroalcoholic extract. Ruthenium red almost completely abolished capsaicin-induced contraction, but had no effect on hydroalcoholic extract-mediated contraction. Substance P and the hydroalcoholic extract caused marked potentiation of the twitch response in the preparations field stimulated. The facilitatory effect of substance P, but not that of hydroalcoholic extract, was prevented by the NK1 (FK 888), but not by NK2 (SR 48968) antagonist.

We concluded that contraction induced by hydroalcoholic extract of Phyllanthus urinaria in the guinea pig urinary bladder involves direct action on smooth muscle and relies on the mobilization of extracellular calcium influx unrelated to activation of L- and N-type calcium channels or activation of protein kinase C mechanisms. In addition contraction caused by the hydroalcoholic extract of Phyllanthus urinaria in guinea-pig urinary bladder does not involve the activation of tachykinin or vanilloid receptors.
Protection by Almagate of Ethanol-induced Gastric Mucosal Damage in Rats
Authors: Esplugues J V , Barrachina M D , Martínez-Cuesta M A , Calatayud S , Moreno L , Fernandez A , Puig J , Esplugues J
Published: April 2011

The study was designed to analyse the protective effects of almagate on a model of gastric injury, ethanol-induced mucosal damage, in which acid plays little, if any, role.

Pretreatment with almagate dose-dependently reduced the level of gastric damage induced by oral administration of 1mL 100% ethanol. Administration of 12 μmol kg−1 almagate 30 min before ethanol significantly reduced the area of mucosal damage by 65 ± 10%, and the maximum level of inhibition (74 ± 11%) was obtained with 150 μmol kg−1 almagate. Administration of higher doses of almagate (200–250 μmol kg−1) did not result in any further increase in the level of protection against ethanol-induced gastric damage. Administration of 1 mL 100% ethanol induces substantial damage to the gastric mucosa, with nearly 40% of the length of the section evaluated exhibiting deep necrotic and haemorrhagic damage. Pretreatment with almagate caused a significant diminution in all parameters of histological damage, whereas damage to the epithelial cell layer was only significantly reduced by pretreatment with the highest doses evaluated (25, 50 and 150 μmol kg−1).

Administration of aluminium hydroxide did not modify ethanol-induced mucosal damage, even at doses containing concentrations of aluminium higher than those present in gastroprotective doses of almagate. Pretreatment with sucralfate, another aluminium containing compound, at doses of 250 μmiol kg−1 protected the mucosa, although lower doses did not.

The present study has shown that almagate prevents ethanol-induced gastric mucosal damage. This protective effect seems independent of any antacid activity, related to its content in magnesium, and mediated by an increase in gastroprotective prostaglandins in the mucosa of the stomach.
Some Anti-allergic and Anti-inflammatory Actions of 2-N -Carboxamidinonormianserin (FCC5)
Authors: Leitch Ian M , Temple Diana M , Wei He , Boura Alan L A
Published: April 2011

The aims of these studies were to examine the effects of FCC5 (2-carboxamidino-1,2,3,4,10,14b-hexahydrodibenzo (c,f) pyrazino (1,2,-a) azepine HCI), an analogue of mianserin, on immediate type hypersensitivity reactions in-vitro.

The actions of FCC5 were examined on the Schultz-Dale reaction of guinea-pig ileum and on histamine and leukotriene release from human- and guinea-pig-sensitized lung fragments. FCC5 (applied topically) was assessed for anti-inflammatory activity in-vivo against phorbol-12-myristate-13-acetate (PMA)-induced oedema in the mouse ear. FCC5 (IC50 = 017 μM) was a potent inhibitor of the Schultz-Dale reaction in-vitro, as assessed by a concentration-dependent attenuation of egg albumin-induced contractions of sensitized guinea-pig isolated ileum. Using human and guinea-pig isolated sensitized lung fragments, FCC5 (1–100 μM) attenuated antigen-induced release of sulphidopeptidoleukotrienes and histamine. FCC5 (50 μg topically) resembled mianserin and indomethacin in attenuating PMA-induced mouse ear inflammation.

These properties together with previously published evidence of long lasting antihistamine properties in-vivo, suggest that FCC5 has therapeutic potential as an anti-allergic agent, especially in pathological conditions where an inflammatory component is present.
A Pharmacokinetic-pharmacodynamic Linking Model for the α2-Adrenergic Antagonism of Idazoxan on Clonidine-induced Mydriasis in the Rat
Authors: Valles Joaquim , Obach Rossend , Menargues Angel , Pruñonosa Joan , Jane Francesc
Published: April 2011

The relationship between concentration and inhibitory effect of the α2-adrenoceptor antagonist idazoxan on clonidine-induced mydriasis has been studied in the rat using pharmacokinetic-pharmacodynamic simultaneous modelling.

Fifteen minutes after the anaesthesia of rats with sodium pentobarbitone (55 mg kg-1, i.p.), and 5 min after the administration of clonidine (0·3 mg kg−1, i.v.) to rats pretreated with idazoxan (3 mg kg−1, i.v., and 3 and 10 mg kg−1, orally) at different time intervals, pupil diameters were assessed. The pharmacokinetics of idazoxan were adequately described by a monoexponential equation. Using a pharmacokinetic-pharmacodynamic linking model, the concentration-effect relationships of idazoxan were derived, and were quantified by the inhibitory simple Emax model. At the effect compartment, the estimated apparent IC50 was 153·6 ng mL−1. Values of clearance, volume of distribution and elimination half-life were 71·2 mL kg−1 min−1, 3134 mL kg−1 and 30-5 min, respectively.

These results could contribute to better characterization of the pharmacodynamic and toxicological profiles of idazoxan in experimental models in which a different pharmacokinetic behaviour of the drug is presumed.
An Evaluation of the Mechanisms of Drug Release from Glyceride Bases
Authors: Sutananta Wanchai , Craig Duncan Q M , Newton J Michael
Published: April 2011

A series of dispersions containing theophylline in Gelucires 43/01, 54/02, 50/02, 50/13 and 55/18 was prepared and the physical structures studied using differential scanning calorimetry. The dissolution, erosion and swelling profiles of the drug dispersions were assessed.

Gelucire 43/01 and 54/02 systems were found to release the drug by a simple diffusion mechanism, with no evidence for erosion or swelling being noted. Gelucire 55/18, however, showed a more complex mechanism involving both diffusion and erosion. On increasing the drug load within the matrices, the predominance of the erosion mechanism increased. Drug release from Gelucire 50/13 matrices took place principally by erosion, although the process was dominated by swelling and subsequent disintegration of the matrix, rather than simple dissolution of the base as was found for Gelucire 55/18. Gelucire 50/02 matrices also exhibited swelling, although drug release occurred predominantly via diffusion.

The study, therefore, demonstrates that Gelucires may release incorporated drugs by a number of mechanisms depending on the chemical composition of the base.
Blood Polyamines in the Rat
Authors: De Vera N , Camón L , Martínez E
Published: April 2011

The physiological concentrations of polyamines in plasma, serum and red blood cells were determined in male Wistar rats, using HPLC with fluorometric detection.

The analysis of the metabolic ratio between polyamines and the frontal cortex/plasma relationship for putrescine, spermidine and spermine, suggest the existence of common mechanisms in the regulation of spermidine in blood and brain.
Fluorescent Substances and High Molecular Weight Protein Aggregates Formed in Rat Heart Mitochondria upon Doxorubicin-induced Lipid Peroxidation
Authors: Fukuda Fumiyasu , Kitada Mitsuo , Horie Toshiharu , Awazu Shoji
Published: April 2011

A rat heart mitochondrial suspension was incubated with doxorubicin, FeCl3 and NADH.

Fluorescent substances and high molecular weight protein aggregates were observed in the mitochondrial membranes upon the formation of thiobarbituric acid-reactive substances.

Since both fluorescent substances and high molecular weight protein aggregates are retained in mitochondrial membranes, they can be of use in the clarification of the site of doxorubicin-induced lipid peroxidation.
Aniracetam, a Pyrrolidinone-type Cognition Enhancer, Attenuates the Hydroxyl Free Radical Formation in the Brain of Mice with Brain Ischaemia
Authors: Himori Norio , Suzuki Tatsuya , Ueno Ken-Ichi
Published: April 2011

We demonstrate here that aniracetam has the ability to block the formation of cytotoxic hydroxyl radicals (· OH) during ischaemia-reperfusion of mouse brain.

The fact that brain ischaemia for 40 min followed by reperfusion increased ·OH was evidenced by detection of a peaked increase at 20 min after an ischaemic insult in the formation of 2,3-dihydroxy-benzoate (DHBA) from salicylate in cerebroventricular perfusate, a means of monitoring ·OH formation. A clearcut increase in dopamine was also observed during and after brain ischaemia. The ischaemia-reperfusion mice given aniracetam at an intraperitoneal dose of 30 or 100 mg kg−1 showed a smaller increase in the formation of DHBA than those given the vehicle only.

Aniracetam at 100 mg kg−1 significantly suppressed the formation of DHBA by approximately 80%, becoming evident at 20 min after reperfusion and thereafter. Protection against death in mice insulted with a 40-min brain ischaemia (3/13 vs 13/25) was observed following 100 mg kg−1 aniracetam. The increase in the dopamine levels was substantially reduced following aniracetam treatment and the reduction became significant at 20 min after reperfusion and thereafter in parallel with attenuation by aniracetam of DHBA formation.

This finding suggests that the inhibitory activity of aniracetam in attenuating the hydroxyl free-radical formation in ischaemic mice is probably due, at least in part, to its palliative action on the dopaminergic neurons.
Scavenging of Free-radicals and Inhibition of Lipid Peroxidation by 3-Phenylsydnone
Authors: Narla Raja Sekhar , Rao M N A
Published: April 2011

The antioxidant properties of 3-phenylsydnone were studied in various models in-vitro.

3-Phenylsydnone scavenged the stable free radical, 1,1-diphenyl-2-picrylhydrazyl, and inhibited the degradation of deoxyribose mediated by hydroxyl radicals, although, to a lesser extent than trolox, a water soluble analogue of vitamin E. Many antioxidants possess pro-oxidant properties due to their ability to reduce ferric ions; however, 3-phenylsydnone was free from pro-oxidant properties, and also inhibited the lipid peroxidation induced by iron, in rat brain homogenates.
Dose Regimen Adjustment for Milrinone in Congestive Heart Failure Patients with Moderate and Severe Renal Failure
Authors: Woolfrey S G , Hegbrant J , Thysell H , Fox P A , Lendrem D W , Lockwood G F , Lasher K , Rogers J , Greenslade D
Published: April 2011

This study was designed to test a proposed dose modification for intravenous milrinone in congestive heart failure patients (CHF, NYHA I-II) with either moderate or severe renal impairment.

All the patients were administered an intravenous loading dose of drug at 50 μg kg-1 over 10 min. This was followed by an 18 h maintenance infusion of milrinone at 0·45 or 0·35 μg kg−1 min−1 for the moderate (chromium-EDTA clearance of 31–75 mL min−1, n = 10) and severe renally impaired subjects (chromium-EDTA of clearance 10–30 mL min−1, n = 11), respectively. Plasma and urine samples were collected for up to 34 h and analysed for parent drug by validated HPLC methods. The mean (± s.d.) steady-state plasma concentrations of milrinone were within the therapeutic range (100–300 ng mL−1) for both groups, with values of 239 ± 71 ng mL−1 and 269 ± 32 ng mL−1 for the moderate and severe patients, respectively. No statistical differences were observed between the steady-state values for the two groups. With the exception of two patients per group, individual steady-state levels were also within the therapeutic range. Those outside the nominal range showed steady-state levels, ranging between 308 and 353 ng mL−1, that were not associated with any serious adverse events. As predicted for this highly renally cleared drug, there were differences (P < 0·001) in the total plasma clearance (CLP), renal clearance (CLr), and plasma terminal half-life (t1/2) of drug, with values in the severe group being 44% lower, 75% lower, and about 134% longer respectively, when compared with the moderate group. High (correlation coefficient > 0·8) and significant correlations (P < 0·001) were observed between CLP and CLr and the degree of renal impairment (chromium-EDTA clearance). The apparent volume of distribution was approximately 40% higher (P < 0·01) in the severe group compared with that for the moderate group (moderates were 0·443 ± 0·155 L kg−1). This volume difference suggests a decrease in the plasma protein-binding of milrinone because of the renal disease. The fraction of drug excreted in the urine was 0·705 ± 0·100 for the moderate group and 0·320 ± 0·089 for the severe group (P < 0·001).

These results may suggest an increase in non-renal clearance of the compound, representing a partial compensation mechanism for the reduced renal function. In conclusion, this study has confirmed that the current dose reductions recommended for the use of intravenous milrinone in CHF patients with impaired renal function will yield plasma concentrations of the drug within the therapeutic range.
The Influence of 17-β-Oestradiol and the Natural Oestrous Cycle on α-Adrenoceptor-mediated Responses of the Cardiovascular System in the Rat
Authors: Austin Clare , Chess-Williams Russell
Published: April 2011

The effect of 17β-oestradiol pretreatment and the natural oestrous cycle on responses of rat cardiac and vascular α-adrenoceptors was investigated.

It was found that treatment with the oestrogen had no effect on cardiac adrenoceptor sensitivity, while pretreatment with the hormone caused a significant increase in vascular α2-, but not vascular α1-adrenoceptor responsiveness. Pressor responses of pithed rats to selective oer or α2-adrenoceptor agonists did not alter, however, during the natural oestrous cycle.

These findings suggest that changes in oestrogen levels are capable of altering α-adrenoceptor-mediated vascular responses but that the relatively small changes in oestrogen which may occur throughout the natural oestrous cycle do not appear to alter the responses of these vascular α-adrenoceptors.
Mechanisms Involved in Electrically-induced Responses of Rat Seminal Vesicles
Authors: Sadraei Hassan , Large Bryan J , Hughes Ian E
Published: April 2011

Contractile responses of rat isolated seminal vesicle were elicited by electrical field stimulation (EFS, 10 Hz, 1 ms, 40 V for 5 s), noradrenaline (1 times 10−5 m) and carbachol (1 times 10−5 m).

Guanethidine (2 times 10−5−5 times 10−4 m) progressively reduced the contraction induced by EFS and carbachol to 24 ± 2 and 10 ± 2%, respectively, at the highest concentration (n = 6), while potentiating noradrenaline contraction to a maximum of 154 ± 14% at 2 times 10−5 m (n = 6). Prazosin (1 times 10−6 m) and atropine (2·5 times 10−7 m) completely abolished the response to the corresponding agonist and each reduced the response to EFS to 64 ± 8 and 61 ± 3%, respectively (n = 6). In the presence of both atropine and prazosin a small contraction to EFS remained (14 ± 4%, n = 6), which is unlikely to be due to ATP, since exogenous ATP did not induce a contractile response and had an inhibitory effect on EFS-induced responses. Clonidine (1·25 times 10−5 m) completely blocked responses to noradrenaline and reduced the response to EFS to 68 ± 7% (n = 6). However, when both the adrenergic and cholinergic components of EFS were blocked by prazosin and atropine, clonidine potentiated the remaining response to EFS (323 ± 82%, n = 4). Yohimbine (1 times 10−5 m) blocked the response to noradrenaline and reduced the response to EFS to 37 ± 5% (n = 6) while the carbachol response was unaffected. Both cholinergic and noradrenergic components contribute to the response to EFS but there appears to be little involvement of presynaptic α2-adrenoceptors in regulating neurotransmitter release.

The actions of clonidine and yohimbine are compatible with the suggestion that their effects are due to postsynaptic α1-adrenoceptor blockade.
The Involvement of Dipeptidyl Peptidase IV in Brush-border Degradation of GRF(1–29)NH2 by Intestinal Mucosal Cells
Authors: Bai Jane P F , Chang Li-Ling
Published: April 2011

GRF(1–29)NH2 is degraded mainly by dipeptidyl peptidase IV (DPP IV) in plasma, resulting in inactivated GRF(3–29)NH2. To understand whether improving stability of GRF(1–29)NH2 in the plasma will result in enhanced stability in intestinal mucosal cells, stability of GRF(1–29)NH2 and [desNH2Tyr1,d-Ala2,Ala15]-GRF(1–29)NH2 in rat intestine brush-border membrane and homogenate was examined.

[desNH2Tyr1,d-Ala2,Ala15]-GRF(1–29)NH2, resistant to plasma DPP IV, was much more stable than GRF(1–29)NH2 in enterocytes. Gradient HPLC analysis, mass balance analysis and studies of inhibitor effects revealed that GRF(3–29)NH2 was the major metabolite of GRF(1–29)NH2 due to the action of DPP IV during incubation with brush-border membranes.

It is concluded that the design of peptide analogues to resist plasma enzymes dramatically increases stability in intestinal epithelium.
Effects of Phorbol 12,13-Diacetate and Its Influence on Spasmogenic Responses in Normal and Sensitized Guinea-pig Trachea
Authors: De Diego A , Cortijo J , Villagrasa V , Perpiñá M , Esplugues J , Morcillo E J
Published: April 2011

We have studied the effects of phorbol 12,13-diacetate (PDA) and its influence on a variety of spasmogenic responses in trachea isolated in from normal and sensitized guinea-pigs.

Tracheal preparations were denuded of epithelium, treated with indomethacin (2·8 μm), and cooled to 20°C. In these experimental conditions, tracheal strips contracted to PDA (0·1 nm-1 μm). Contractions to PDA (1 μm) were greater in sensitized tissues. In normal trachea, contractions to PDA (0·1 μm) were depressed by H-7, 1-(5-isoquinolinyl-sulphonyl)-2-methylpiperazine, (50 μm), amiloride (10 μm), verapamil (10 μm) and Ca2+-free exposure. Similar effects were obtained in sensitized trachea except that PDA-induced contraction was resistant to verapamil and Ca2+-free exposure.

Cooling (20°C) of normal trachea substantially depressed the response to CaCl2 (in K+-depolarized tissues), KC1, histamine and 5-hydroxytryptamine without affecting the spasm induced by acetylcholine. This inhibitory effect of cooling was not observed in sensitized trachea. PDA (0·1 μm) did not affect spasmogenic responses at 37°C but counteracted the inhibitory effect of cooling in normal trachea. PDA had no effect on sensitized tissues. PDA (0·1-1μm) did not alter Ca2+-induced contraction of skinned normal and sensitized trachea.

These results support the hypothesis that intracellularly stored Ca2+ plays an important role in the activation of sensitized tracheal muscle.
Rat Tissue Concentrations of Chlorimipramine, Chlorpromazine and their N-Demethylated Metabolites after a Single Oral Dose of the Parent Compounds
Authors: Sgaragli Gian Pietro , Valoti Massimo , Palmi Mitri , Frosini Maria , Giovannini Maria Grazia , Bianchi Loria , Corte Laura Della
Published: April 2011

A single oral dose of 90 mg kg−1 chlorimipramine or chlorpromazine, corresponding to 54.5 or 55.9 μmol, respectively, was given to male Sprague-Dawley rats and concentrations of parent drugs and their N-desmethyl metabolites measured by gas chromatography in plasma and major organs (brain, liver, lung, kidney, heart, spleen and peritoneal fat).

In the case of chlorimipramine, N-desmethyl metabolite levels were consistently higher than those of the parent drug for the entire observation period of 24 h in all tissues except fat, while lower N-desmethyl metabolite/parent compound ratios were observed for chlorpromazine. N-Desmethyl metabolite kinetics of chlorimipramine appeared to be elimination-rate limited, while those of chlorpromazine were formation-rate limited. In all analysed organs, the maximum detectable drug + metabolite concentrations accounted for only 2·3 and 4·6% of the initial dose of chlorimipramine and chlorpromazine. Chlorpromazine treatment gave rise to an area under the total amount-time curve (AUC0–24) for parent drug + metabolites, 3·9-fold that for chlorimipramine. Closer scrutiny discloses a conversion ratio of parent compound to N-desmethyl metabolite of 1·1 for chlorpromazine and of 2·2 for chlorimipramine, indicating the greater efficiency of chlorimipramine metabolism in all compartments. The expected high conversion index found in the liver (2·3) reaches its maximum of 5·4 in the lung. Fractional data analysis of chlorimipramine and chlorpromazine distribution patterns revealed greater organ transfer for the N-desmethyl metabolites than for the more stably-located parent compounds. The N-desmethyl metabolites of chlorimipramine apparently moved from liver to lung, kidney and spleen, whereas N-desmethylchlor-promazine moved preferentially to the brain and lung tissue.

This single dose study of chlorimipramine and chlorpromazine kinetics, highlights the two distinct dispositional processes at work in the rat in all likelihood, attributable to different absorption patterns, to a slower metabolism and, thus, to the longer persistence of chlorpromazine.
Relaxant Effect of Tetrazepam on Rat Uterine Smooth Muscle: Role of Calcium Movement
Authors: Perez-Guerrero C , Herrera M D , Marhuenda E
Published: April 2011

Tetrazepam is a benzodiazepine derivative clinically used as a muscle relaxant. The aim of the present work was to examine its effect on uterine smooth muscle of the rat in estrus.

Tetrazepam required micromolar concentractions to relax contractile responses induced by KCl and acetylcholine in Ca2+ solution, but not oxytocin-induced contraction. In Ca2+-free solution, tetrazepam inhibited Ca2+-induced contractions in depolarized uterus and vanadate-induced contractions.

We suggest that tetrazepam relaxes contractile responses induced by activation of voltage-sensitive calcium channels and receptor-operated calcium channels with little selectivity or that it antagonizes the effect of calcium at subsequent steps, possibly intracellular stores sensitive to vanadate but not sensitive to oxytocin. The inhibition of contraction of rat uterus is not related to high-affinity peripheral benzodiazepine binding sites.
The Presence of Insulin-degrading Enzyme in Human Ileal and Colonic Mucosal Cells
Authors: Bai Jane P F , Hong Hae-Jin , Enberger David A Roth , Wong W Douglas , Buls John G
Published: April 2011

The aim of this research is to characterize the presence of insulin-degrading enzyme in human colon and ileal mucosal cells. Biochemical studies, including the activity-pH profiles, the effects of enzyme inhibitors, immunoprecipitation and western blots, were conducted.

The majority of insulin-degrading activity in colon mucosal cells was localized in the cytosol. In both colon and ileum, cytosolic insulin-degrading activities had a pH optimum at pH 7.5, and were extensively inhibited by each of N-ethylmaleimide, p-chloromercuribenzoate, and 1,10-phenanthroline, but were very weakly affected by each of leupeptin, chymostatin, diisopropyl phosphofluoridate and soybean trypsin inhibitor. In the colon and ileum, more than 93% and 96%, respectively, of cytosolic insulin-degrading activities were removed by the mouse monoclonal antibody to human RBC insulin-degrading enzyme, as compared with less than 20% by the normal mouse IgG for both tissues. Further, a western blot analysis revealed that a cytosolic protein of 110 kD, in both human colon and ileum, reacted with the monoclonal antibody to insulin-degrading enzyme.

It is concluded that insulin-degrading enzyme is present in the cytosol of human colon and ileal mucosal cells.
In-vitro Metabolic Interaction of Bunitrolol Enantiomers in Rabbit Liver Microsomes
Authors: Narimatsu Shizuo , Mizukami Takao , Huang Yong , Masubuchi Yasuhiro , Suzuki Tokuji
Published: April 2011

We have examined the 4-hydroxylation of bunitrolol in rabbit and rat liver microsomes.

Significant species differences (rabbit < rat of both sexes) and sex (male > female of both species) were observed in the formation of 4-hydroxybunitrolol from racemic bunitrolol (10 μM). The 4-hydroxylation of bunitrolol racemate and enantiomers showed biphasic kinetics, a low-Km system and a high-K.m system, in liver microsomes from rabbits of both sexes. There were significant differences in Km and Vmax values [(+) > (-)] for 4-hydroxylations of (+)-bunitrolol and (-)-bunitrolol in the low-K.m system. Furthermore, the rate of clearance (Vmax/Km) was 20- to 200-fold for the low-Km system compared with the high-Km system, indicating that enzymes in the low-Km system play a major part in the rabbit liver microsomal bunitrolol metabolism. Inhibition studies using cytochrome P450 inhibitors such as quinidine, quinine, and α-naphthoflavone or polyclonal antibodies raised against rat P450-2D and −1A enzymes did not make clear which P450 enzymes are involved in bunitrolol 4-hydroxylation in rabbit liver microsomes. The 4-hydroxylase activity of (+)-bunitrolol was slightly higher than that of (-)-bunitrolol in separated incubations containing male rabbit liver microsomes and an enantiomer concentration of 10 μM. However, the 4-hydroxylation of (+)-bunitrolol (10 μM) was markedly suppressed in the presence of its antipode (10 μM), whereas (-)-bunitrolol 4-hydroxylation was not affected by the presence of its antipode, resulting in a change of the stereoselectivity from (+) > (-) for enantiomer to (+) < (-) for racemate.

The difference in the Michaelis constants in the low-Km system, where the Km value of (-)-bunitrolol is one-eighth that of (+)-bunitrolol, is thought to cause the change in the stereoselectivity in rabbit liver microsome-mediated bunitrolol 4-hydroxylation.
Physicochemical Properties of Calcium Polycarbophil, a Water-absorbing Polymer
Authors: Yamada Takehisa , Nagata Osamu , Tamai Ikumi , Tsuji Akira
Published: April 2011

The physicochemical properties of calcium polycarbophil were examined.

Calcium polycarbophil was decalcified rapidly under acidic conditions, affording polycarbophil. Polycarbophil absorbed about 10 times its own weight of water under acidic conditions, but the swelling ratio markedly increased at above pH 4.0 and reached 70 times the initial weight under neutral conditions. The swelling of polycarbophil was not affected by non-ionic osmolarity, but was affected by ionic strength, showing a decrease with increase of ionic strength. Monovalent metal ions such as sodium and potassium ions in gastrointestinal fluid did not reduce the equilibrium swelling of polycarbophil, but divalent ions such as calcium and magnesium ions did. However, calcium ion only slightly reduced the equilibrium swelling under sodium-rich conditions. The viscosity (as an indicator of fluidity) of polycarbophil was larger than that of CMC-Na at every shear rate and polymer content examined.
Biodegradable Injectable Implant Systems for Long Term Drug Delivery Using Poly (Lactic-co-glycolic) Acid Copolymers
Authors: Chandrashekar G , Udupa N
Published: April 2011

Poly (lactide-co-glycolide) (PLG), is one of the most widely employed biodegradable synthetic polymers for sustained-release preparations. In the present work, PLG (50:50) copolymer has been used to deliver diclofenac sodium in the form of microspheres and in situ gel-forming systems, both of which can be injected subcutaneously.

The pharmacodynamic and pharmacokinetic studies in the adjuvant-induced arthritic rats showed that the microspheres offered steady therapeutic levels of the drug in the plasma for about 16 days following a single subcutaneous injection. However, the in situ gel-forming system provided a significantly higher maximum plasma concentration and increased inhibition of inflammation, maintained for about 10 days.

Injectable microspheres and in situ gel-forming implant systems of PLG (50: 50) copolymer may therefore be considered as prospective implantable controlled-release dosage forms to deliver drugs in long-term therapy of chronic ailments.
Effectiveness and Mode of Action of Isopropyl Myristate as a Permeation Enhancer for Naproxen through Shed Snake Skin
Authors: Suh Hearan , Jun H W
Published: April 2011

The effectiveness and mode of action of isopropyl myristate (IPM) as an enhancer for the permeation of naproxen through shed snake skin have been investigated.

The highest naproxen permeability was afforded by IPM (36.2 × 10−4 cm h−1), followed by menthol (25.0 × 10−4 cm h−1), oleic acid (11.1 × 10−4 cm h−1), azone (7.3 × 10−4 cm h−1)_and control (1.4 × 10−4 cm h−1). Whereas the permeability of un-ionized naproxen (47.4 × 10−5 cm h−1) was much greater than that of ionized naproxen (1.11 × 10−5 cm h−1), IPM-treatment of the intact skin increased the flux of ionized naproxen significantly more (50−fold) than that of un-ionized naproxen (15−fold). The large effect of pH on the permeation of naproxen through the intact stratum corneum became insignificant after extraction of lipids from the skin. Similar permeation of naproxen through intact and delipidized skin after IPM treatment indicated that the lipid barrier of the skin was largely impaired by IPM. Direct application of IPM to skin yielded a 2.6−fold higher naproxen permeability than the application of IPM as a gel. A greater amount of naproxen was absorbed from 1% test gel (pH 5) containing IPM than from 10% commercial gel (pH 7) containing no IPM.

These results show that use of IPM can significantly improve the bioavailability of naproxen in topical preparations.
Veratridine Augments and BDF 9148 Attenuates the Spontaneous Contractile Force of the Rat Portal Vein
Authors: Doggrell Sheila A , Bishop Brett E
Published: April 2011

Veratridine and BDF 9148 both increase the force of myocardial contraction but their effects on the contractility of vascular smooth muscle are largely unknown. We have examined the effects of the drugs on the contractile force of the rat portal vein.

The force responses of the rat portal vein were not altered by tetrodotoxin (≤ 30 μM) but were augmented by Bay K 8644 (10 nM-10 μM), and attenuated by nifedipine (10 nM-10 μM). Veratridine slightly reduced the force of spontaneous contractions at concentrations of 0.1−1 μM, then augmented the force at concentrations up to 100 μM. The reduction was prevented by 30 nM tetrodotoxin; a higher concentration of 3 μM prevented the effect of veratridine. Pretreatment with nifedipine at 30 nM reduced the maximum augmentation observed with veratridine. BDF 9148 (0.3−300 μM) attenuated the force and this attenuation was increased in the presence of tetrodotoxin at 3 μM but reversed to an augmentation in the presence of Bay K 8644 at 10 μM. The augmentation produced by BDF 9148 in the presence of Bay K 8644 was reduced by tetrodotoxin at 30 nM.

These results suggest that veratridine predominantly opens sodium channels which in turn open voltage-dependent calcium channels to augment the force responses of the rat portal vein, but attenuate force in the presence of sodium-channel blockade with tetrodotoxin. BDF 9148 predominantly closes calcium channels to attenuate the force of the rat portal vein but in the presence of maximum calcium-channel opening with Bay K 8644 augments force probably by opening sodium channels.
On the In-vivo Modulation of Neostriatal Dopamine Release by Fluoxetine and 5−Hydroxy-L-tryptophan in Conscious Rats
Authors: Li XI-Ming , Perry Kenneth W , Fuller Ray W
Published: April 2011

To help determine the nature of serotonergic regulation of dopamine activity in the brain an in-vivo microdialysis study has been performed in conscious rats to investigate the modulation of dopamine release in the neostriatum by 5−hydroxytryptamine (5−HT).

The 5−HT uptake inhibitor, fluoxetine, and the 5−HT precursor, 5−hydroxy-L-tryptophan (5−HTP), were used to produce an increase in extracellular 5−HT concentration. Systemic administration of fluoxetine (10 mg kg−1, s.c.) produced a 2−to 3−fold increase in extracellular 5−HT concentration but did not change extracellular dopamine concentration in the neostriatum. Co-administration of fluoxetine and 5−HTP (40 mg kg−1, s.c; 60−90 min after fluoxetine) caused a highly significant tenfold increase in extracellular 5−HT concentration in the neostriatum with a slight but non-significant decrease in extracellular dopamine concentration. Pergolide, a dopamine D2 agonist, given systemically caused a dramatic decrease in extracellular dopamine concentration demonstrating the responsiveness of the neurons.

These results demonstrate that high concentrations of extracellular 5−HT do not modulate dopamine release in the neostriatum. The possibility that different 5−HT receptor subtypes may mediate different regulation of dopamine release remains to be explored.
An Exploration of the Structure-activity Relationships of 4−Aminoquinolines: Novel Antimalarials with Activity In-vivo
Authors: Ismail F M D , DAscombe M J , CArr P , NOrth S E
Published: April 2011

The structure-activity relationships of bisquinolines, a potentially important group of novel antimalarial drugs, were studied.

The high-temperature (180−250°C) synthesis of 4−aminoquinolines, including bisquinolines, by nucleophilic displacement was both fast and efficient. Several bisquinolines including (±)-trans-N1,N2-bis(7−trifluoroquin-olin-4−yl)cyclohexane-1,2−diamine and 1R,2R-(-)-, 1S,2S-(+)-, (±)-trans- and cis-N1,N2-bis(7−chloroquin-olin-4−yl)cyclohexane-1,2−diamine exhibited potent activity against Plasmodium berghei in mice; (±)-trans-N1,N2-bis(7−chloroquinolin-4−yl)cyclohexane-1,2−diamine was orally active.

Our results indicate that these compounds conform to a putative receptor for quinoline antimalarials. In addition, a 7−haloquinoline linked by a heterocyclic bridge, at the 4−position, to another heterocycle (such as an acridine at the 9−position) maximally occupies the active site of our postulated target.
In-vivo Evaluation in Man of a Hydrophilic Matrix Containing Propylthiouracil
Authors: Kabanda Louis , Lefebvre Romain Adelin , Remon Jean Paul
Published: April 2011

To reduce the number of administrations of propylthiouracil required to treat hyperthyroidism, the bioavailability and sustained-release characteristics of 300 mg propylthiouracil formulated in hydrophilic matrix tablets were evaluated after single oral administration in healthy male volunteers. A conventional tablet was chosen as the reference formulation.

For tablets formulated from three different types of hydroxypropylmethylcellulose, K15M, K4M and K100LV, propylthiouracil dissolution in-vitro was 40%, 51% and 100%, respectively, in 8 h. The three matrix formulations showed sustained plasma concentration-time profiles. The relative bioavailability was 50, 51 and 87%, respectively, for K4M, K15M and K.100LV hydroxypropylmethylcellulose matrix tablets. When reverse triiodothyronine concentrations were plotted against the corresponding propylthiouracil concentrations, an antihysteresis loop was observed with the conventional tablets and the K100LV matrix tablet. A linear concentration-response curve was obtained for both the K4M and K15M formulations.

The results showed that the K100LV matrix tablet gave a sustained plasma concentration-time profile and a bioavailability and extrathyroidal effect similar to that of a conventional tablet.
Effect of YM934, a Novel Potassium-Channel Opener, in Various Experimental Asthma Models in Guinea-pigs
Authors: Ishikawa Jun , Saitoh Chikashi , Masaki Katsuhiro , Asano Masaharu
Published: April 2011

YM934 is a novel synthetic potassium-channel opener. We have investigated its anti-asthma effect after intravenous (i.v.) and oral (p.o.) administration in various experimental asthma models in the guinea-pig, and compared the results with those for lemakalim, theophylline and salbutamol.

In an ovalbumin-active sensitization anaphylaxis asthma model, YM934, lemakalim, theophylline and salbutamol dose-dependently prolonged the time before the occurrence of asthma attacks and reduced the mortality rate. The respective ED50 values (dose required to prolong by 50% the time before the occurrence of attacks) of the anti-asthma effects of YM934, lemakalim, theophylline and salbutamol were 6, 340, 30 000, and 45 μg kg−1 (i.v.); the efficacy ratios were YM934 (1) > salbutamol (1/9) > lemakalim (1/57) » theophylline (1/5000). YM934 also prolonged the period before the occurrence of attacks in the anti-BSA (bovine serum albumin) serum-passive sensitization anaphylaxis, histamine-induced and methacholine-induced asthma models, with respective ED50 values for these models of 15, 22 and 20 μg kg−1 (i.v.). Among these models a reduction in mortality rate was seen in the histamine- and methacholine-induced asthma models. After oral administration, YM934 showed an anti-asthma effect in the ovalbumin-active sensitization anaphylaxis, histamine-induced and methacholine-induced asthma models, with respective ED50 values of 38, 44 and 193 μg kg−1. YM934 was 5–6 times more potent than salbutamol. These results indicate that YM934 has potent anti-asthma activity, and that this activity is mainly attributable to bronchodilation, most likely mediated through its potassium-channel opening activity.
Pulmonary Catabolism of Interleukin 6 Evaluated by Lung Perfusion of Normal and Smoker Rats
Authors: Pessina G P , Paulesu L , Corradeschi F , Aldinucci C , Luzzi E , Bocci V
Published: April 2011

Cytokines such as interleukin 6 are involved in the pulmonary inflammation arising as a result of smoking. By use of isolated and perfused lung preparations we have evaluated the role of the lungs in the catabolism of human recombinant interleukin 6 both in normal rats and in rats subjected to an acute cigarette smoking episode.

When interleukin 6 was incorporated into the lung perfusion medium, neither control nor smoke-exposed rat lungs cleared the cytokine and only 0.1 ± 0.2% of the total dose was recovered in the bronchoalveolar lavage fluid. When, on the other hand, the same amount of interleukin 6 was instilled into the bronchoalveolar tree, concentrations of the cytokine in the perfusate increased progressively so that after 3 h up to 70.1 ± 9.8% and 40.9 ± 22.5% of the administered dose, as measured by immunoenzymatic test, had been transferred from the bronchial lumen to the perfusion medium of either control or smoker rat lungs, respectively, indicating significantly (P < 005) different behaviour of the cytokine in the two experimental groups. Total recoveries of the administered interleukin 6 evaluated in smoke-exposed rat lungs were 55.3 ± 23.2%, significantly lower than those for control rat lungs (83.9 ± 11%). Determination of biological activity gave values always lower than those measured by immunoenzymatic test, indicating loss of biological activity during the transalveolar transit.

It appears that the transfer of interleukin 6, especially in smokers, is almost exclusively unidirectional, from the alveolar space to the plasmatic pool with degradation during the transalveolar passage.
Oral Sustained-release Cisplatin Capsule
Authors: Houjou Takeshi , Nakano Kousuke , Ike Osamu , Wada Hiromi , Hitomi Sigeki , Shinmi Yuuko , Danno Noriyuki , Yoshikawa Yukako , Takada Kanji
Published: April 2011

An oral sustained-release cisplatin preparation was prepared by combining microporous water-insoluble pharmaceutical polymer, ethylcellulose, a membrane and a gel-forming polymer, poly(acrylic) acid (Carbopol). As cisplatin is an extremely hydrophilic and small compound, it was difficult to control the release rate solely by the micropores on the ethylcellulose capsule.

To retain cisplatin within the capsule, gel-forming polymer was formulated inside the capsule. The release rate of cisplatin was dependent both on the number of micropores of the capsule and the formulated amount of Carbopol. The number of micropores ranged from 20 and 30 to 60, and the formulated amount of Carbopol varied from 15 to 100 mg. In-vitro release experiments suggested that the release rate decreased as the formulated amount of Carbopol increased when the pore number was 60 and 30. However, when pore number was decreased to 20, the effect of the amount of Carbopol was not clearly observed.

In the in-vivo study using rabbits, the sustained-release cisplatin capsule was evaluated in comparison with solution after oral administration of 20 mg drug. With the pore number of 60, Cmax was 0.46 ± 0.02 μg mL−1 at 4 h and thereafter serum concentrations declined rapidly. When the pore number was 30, serum cisplatin level-time profiles showed long-acting patterns and AUC was reversely correlated with the formulated amount of Carbopol. Cmax and tmax were 0.41 ± 0.02 μg mL−1 and 3.33 ± 0.88 h, respectively and 0.23 ± 0.01 μg mL−1 was obtained at 24 h after oral administration of capsule having 30 pores and 15 mg of Carbopol.

We conclude that the possibility of developing an oral sustained-release cisplatin preparation is feasible.
Circadian Variation of α1-Adrenoceptor-mediated Pressor Response to Phenylephrine in Man
Authors: Tham Tony C K , Guy Suzanne , Riddell James G , Shanks Robin G , Harron Dean W G
Published: April 2011

The variability in the pressor effects of the α1-adrenoceptor agonist phenylephrine was observed under placebo conditions in ten healthy subjects in a double blind randomized study. Phenylephrine infusions were administered before administration of placebo (baseline) and 2, 4, 8, 12, 24 and 48 h later.

The doses of phenylephrine required to increase systolic blood pressure by 20 mmHg after 8 and 12 h (5.30 and 9.30 pm, 81.4 ± 15.3 and 71.1 ± 16.0 μg min−1, respectively) were significantly (P < 0.01) less than the baseline values (8.30 am, 108.0 ± 27.6 g min−1).

These results might indicate a circadian variation in the phenylephrine-induced α-adrenoceptor-mediated vascular response in healthy subjects. These observations lend further insight into circadian variations of vascular tone that might contribute to circadian rhythms in cardiovascular disease.
Synthesis and Anti-inflammatory Effects of Xanthone Derivatives
Authors: Lin Chun-Nan , Chung Mei-Ing , Liou Shiou-Jyh , Lee Tai-Hua , Wang Jip-Pyang
Published: April 2011

Eighteen synthetic xanthone derivatives were tested for their inhibitory effects on the activation of mast cells and neutrophils.

1,3- and 3,5-Dihydroxyxanthone showed strong inhibitory effects on the release of β-glucuronidase and histamine from rat peritoneal mast cells stimulated with compound 48/80. 1,6-Dihydroxyxanthone and 1,3,8-trihydroxyxanthone showed strong inhibitory effects on the release of β-glucuronidase, and β-glucuronidase and lysozyme, respectively, from rat neutrophils stimulated with formyl-Met-Leu-Phe (fMLP). 1,3- and 1,6-Dihydroxyxanthone, 1,3,7-trihydroxyxanthone, and 1,3,5,6-, 2,3,6,7-, and 3,4,5,6-tetrahydroxyxanthone showed potent inhibitory effects on superoxide formation of rat neutrophils stimulated with fMLP. 1,6- and 3,5-Dihydroxyxanthone showed remarkable inhibitory effects on hind-paw oedema induced by polymyxin B in normal as well as in adrenalectomized mice.

These data indicated that the anti-inflammatory effect of these compounds is mediated through the suppression of chemical mediators released from mast cell and neutrophil degranulation.
Neural Network Computer Simulation of Medical Aerosols
Authors: Richardson C J , Barlow D J
Published: April 2011

Preliminary investigations have been conducted to assess the potential for using artificial neural networks to simulate aerosol behaviour, with a view to employing this type of methodology in the evaluation and design of pulmonary drug-delivery systems.

Details are presented of the general purpose software developed for these tasks; it implements a feed-forward back-propagation algorithm with weight decay and connection pruning, the user having complete run-time control of the network architecture and mode of training. A series of exploratory investigations is then reported in which different network structures and training strategies are assessed in terms of their ability to simulate known patterns of fluid flow in simple model systems. The first of these involves simulations of cellular automata-generated data for fluid flow through a partially obstructed two-dimensional pipe. The artificial neural networks are shown to be highly successful in simulating the behaviour of this simple linear system, but with important provisos relating to the information content of the training data and the criteria used to judge when the network is properly trained. A second set of investigations is then reported in which similar networks are used to simulate patterns of fluid flow through aerosol generation devices, using training data furnished through rigorous computational fluid dynamics modelling. These more complex three-dimensional systems are modelled with equal success.

It is concluded that carefully tailored, well trained networks could provide valuable tools not just for predicting but also for analysing the spatial dynamics of pharmaceutical aerosols.