bluuebunny/crossref_metadata_2025_split huggingface dataset:
Does Thyrotropin Cleave Its Cognate Receptor?
Authors: Chazenbalk Gregorio D. , Chen Chun-Rong , McLachlan Sandra M. , Rapoport Basil 
Published: September 2003

Abstract
A recent report of major pathophysiological significance, and opposed to present concepts, is that TSH (but not MS-1, a hamster monoclonal thyroid-stimulating antibody), cleaves the single-chain TSH receptor (TSHR) on the cell surface into its two-subunit form. We reassessed the issue using two approaches. First we wished to confirm the flow-cytometric assay previously used to quantitate TSHR cleavage. We used CHO cell lines expressing large (TSHR-10,000 cells) or conventional (TSHR-0 cells) numbers of TSHR. Cells were preincubated (16 h) in either control medium or medium supplemented with TSH (5 × 10−8m) or MS-1 (10 μg/ml). After stringent washing to maximize removal of residual ligand, we performed flow cytometry with two antibodies, one recognizing only the single-chain TSHR, the other recognizing all (cleaved and uncleaved) TSHRs. TSH pretreatment did not appear to increase TSHR cleavage. Instead we observed ligand occupancy of the TSHR (with MS-1) or fewer receptors on the cell surface (down-regulation), particularly with the TSHR-0 cells. Second, we covalently cross-linked [125I]TSH to monolayers of these cells, an unequivocal method to determine directly the proportion of single-chain and two-subunit TSHR forms. Pretreatment of TSHR-10,000 and TSHR-0 cells with TSH had no effect on the degree of TSHR cleavage. MS-1 slightly reduced spontaneous cleavage. In conclusion, in contrast to a recent report, we show that TSH does not alter the subunit structure of its cognate receptor, and we provide insight into the difficulties associated with the flow-cytometric assay for TSHR cleavage.
Identification of a Contact Site for Residue 19 of Parathyroid Hormone (PTH) and PTH-Related Protein Analogs in Transmembrane Domain Two of the Type 1 PTH Receptor
Authors: Gensure Robert C. , Shimizu Naoto , Tsang Janet , Gardella Thomas J. 
Published: September 2003

AbstractRecent functional studies have suggested that position 19 in PTH interacts with the portion of the PTH-1 receptor (P1R) that contains the extracellular loops and seven transmembrance helices (TMs) (the J domain). We tested this hypothesis using the photoaffinity cross-linking approach. A PTHrP(1–36) analog and a conformationally constrained PTH(1–21) analog, each containing para-benzoyl-l-phenylalanine (Bpa) at position 19, each cross-linked efficiently to the P1R expressed in COS-7 cells, and digestive mapping analysis localized the cross-linked site to the interval (Leu232-Lys240) at the extracellular end of TM2. Point mutation analysis identified Ala234, Val235, and Lys240 as determinants of cross-linking efficiency, and the Lys240→Ala mutation selectively impaired the binding of PTH(1–21) and PTH(1–19) analogs, relative to that of PTH(1–15) analogs. The findings support the hypothesis that residue 19 of the receptor-bound ligand contacts, or is close to, the P1R J domain—specifically, Lys240 at the extracellular end of TM2. The findings also support a molecular model in which the 1–21 region of PTH binds to the extracellular face of the P1R J domain as an α-helix.
S-Nitrosocaptopril: acute in-vivo pulmonary vasodepressor effects in pulmonary hypertensive rats
Authors: Tsui Debbie Y Y , Gambino Agatha , Wanstall Janet C 
Published: September 2003

Abstract
The effects of S-nitrosocaptopril (SNOcap), administered either intravenously or by oral gavage, on pulmonary artery pressure (PAP) were examined in anaesthetised normotensive rats and rats with hypoxic pulmonary hypertension (10% oxygen for 1 week). Mean PAP (MPAP) values in hypoxic and normoxic rats were (mmHg) 26± 1.7 and 15± 1.1, respectively. When given intravenously, 1 mg kg−1 SNOcap reduced MPAP by 28 and 32% in hypoxic and normoxic rats, respectively. The effects of 2 mg kg−1 were no greater than those of 1 mg kg−1. Pulmonary vasodepressor responses reached equilibrium in 1.7$pL0.18 min following intravenous administration. When given orally 30 min before the measurement of PAP, 30 mg kg−1, but not 10 mg kg−1, significantly reduced MPAP in hypoxic rats to 17$pL 1.5 mmHg. These in-vivo data are consistent with previous in-vitro data showing that SNOcap has direct pulmonary vasorelaxant properties in both large and small pulmonary arteries and also show that SNOcap causes pulmonary vasodepression in the setting of pulmonary hypertension. Since SNOcap also inhibits pulmonary vascular angiotensin converting enzyme (ACE) in pulmonary blood vessels (previous study), it would be an interesting drug with which to assess the benefits of direct pulmonary vasodilatation combined with ACE inhibition (which attentuates pulmonary vascular remodelling) in a long-term study in pulmonary hypertension.
The flavonoid quercetin inhibits dimethylnitrosamine-induced liver damage in rats
Authors: Lee Eun-Sil , Lee Hye-Eun , Shin Ji-Young , Yoon Sik , Moon Jeon-Ok 
Published: September 2003

Abstract
Quercetin, one of the most abundant flavonoids in human diet has been reported to exhibit a wide range of pharmacological properties. In this study, we investigated the protective effect of quercetin on hepatic injury induced by dimethylnitrosamine (DMN) in rats. Treatment with DMN caused a significant decrease in body and liver weight. Oral administration of quercetin (10 mg kg−1 daily for 4 weeks) remarkably prevented this DMN-induced loss in body and liver weight and inhibited the elevation of serum alanine transaminase, aspartate transaminase and bilirubin levels. Quercetin also increased serum albumin and hepatic glutathione levels and reduced the hepatic level of malondialdehyde. Furthermore, DMN-induced elevation of hydroxyproline content was reduced in the quercetin treated rats, the result of which was consistent with a reduction in type I collagen mRNA production and histological analysis of liver tissue stained with Sirius red. A reduction in hepatic stellate cell activation, as assessed by α-smooth muscle actin staining, was associated with quercetin treatment as well as a reduction in transforming growth factor-β1 expression. In conclusion, these results demonstrate that quercetin exhibited in-vivo hepatoprotective and anti-fibrogenic effects against DMN-induced liver injury and suggest that quercetin may be useful in the preventing the development of hepatic fibrosis.
Effects of absorption rate on the pre-systemic chiral inversion of ibuprofen in rabbits
Authors: Doki Kosuke , Hayakawa Toru , Lin Wenhui , Yanaguimoto Hitomi , Ding Guohua , Inotsume Nobuo 
Published: September 2003

Abstract
The chiral inversion kinetics of ibuprofen was evaluated after intraduodenal administration of racemic ibuprofen in conventional powder form and sustained-released granules compared with intravenous administration in rabbits. The AUC ratios of the S-(+) and R-(–) enantiomers remained almost constant values with time up to 2 h after administration of sustained-release formulation, while those after administration of the powder increased with time. R-(–) enantiomer to S-(–) enantiomer inversion ratios after intraduodenal administration of the powder form and the sustained-release form, and after intravenous injection were calculated to be 1.63, 1.94 and 1.19, respectively, indicating that pharmacological effects may depend on the absorption rate in rabbits.
Prednisolone 21-sulfate sodium: a colon-specific pro-drug of prednisolone
Authors: Jung Yun Jin , Doh Min Ju , Kim In Ho , Kong Hye Sik , Lee Jeoung Soo , Kim Young Mi 
Published: September 2003

Abstract
Prednisolone 21-sulfate sodium (PDS) was synthesized as a colon-specific pro-drug of prednisolone with the expectation that it would be stable and non-absorbable in the upper intestine and release prednisolone by the action of sulfatase once it was delivered to the colon. In-vitro/in-vivo properties were investigated using rats as test animals. PDS was chemically stable at pH 1.2, 4.5, 6.8 and 8.0, and the apparent partition coefficient was 0.11 in 1-octanol/pH 6.8 buffer solution at 37°C. PDS was stable on incubation with the contents of the stomach or small intestine. When PDS (0.1 mg equiv. of prednisolone) was incubated with the caecal contents (0.05g), prednisolone was produced to a maximum 54% of the dose in 6 h and decreased thereafter, which suggested that reduction of the A ring took place in addition to the hydrolysis by sulfatase. After oral administration of PDS, a small portion of prednisolone was recovered from the cecal contents but not from the small intestine. Neither PDS nor prednisolone was detected in the plasma, suggesting that absorption of PDS is limited. The data demonstrate that the sulfate ester can serve as a novel colon-specific promoiety by limiting the absorption of the pro-drug in the upper intestine and releasing the active compound by the action of microbial sulfatase in the colon.
Selective effect of oleamide, an endogenous sleepinducing lipid amide, on pentylenetetrazole-induced seizures in mice
Authors: Wu Chun-Fu , Li Chun-Li , Song Hong-Rui , Zhang Hua-Feng , Yang Jing-Yu , Wang Yu-Ling 
Published: September 2003

Abstract
The anti-seizure effect of oleamide, an endogenous sleep-inducing fatty acid amide, was studied in mice. Oleamide, in the dose range 43.7–700.0 mg kg−, significantly and dose-dependently inhibited the seizures induced by pentylenetetrazole. However, oleamide showed no inhibitory action on the seizures induced by picrotoxin, strychnine, caffeine or semicarbazide. These results provide the first evidence for the anti-seizure effect of oleamide, and suggest that this effect may be selective to the seizure model induced by pentylenetetrazole.
Inducing a change in the pharmacokinetics and biodistribution of poly-l-lysine in rats by complexation with heparin
Authors: Johnston Thomas P , Kuchimanchi Kamesh R , Alur Hemant , Chittchang Montakarn , Mitra Ashim K 
Published: September 2003

Abstract
The aim of our study was to induce changes in the plasma elimination half-life (t1/2 elim), rate and extent of urinary excretion, and biodistribution of a model macromolecule, poly-l-lysine, in rats following complexation with heparin. Male Sprague-Dawley rats were dosed intravenously with either unfractionated [3H]heparin, FITC-labelled poly-l-lysine, or an [3H]heparin:FITC-labelled poly-l-lysine complex. Serum and blood concentration vs time and urinary excretion profiles were determined as well as the resulting patterns of biodistribution to liver, spleen, kidney, and muscle tissue. While the mean values for the total body clearance of poly-l-lysine and the complex were not significantly different, the volume of distribution and the half-life associated with elimination from the serum were increased greater than 2-fold for the complex compared with free poly-l-lysine. The rate and extent of elimination in the urine followed the relative rank order; heparin &gt;poly-l-lysine&gt; heparin:poly-l-lysine complex. Thirty minutes following intravenous administration, there was significantly more tissue deposition/uptake of the complex in the liver, kidney, and muscle, but not the spleen, when compared with poly-l-lysine administered alone. Complexation of heparin to poly-l-lysine effectively increased the fraction of an administered dose of poly-l-lysine that was deposited in liver, kidney, and muscle tissue. Due to the macromolecular complex being nontoxic and uncharged, potentially it might serve as a suitable carrier for both conventional and peptidic drugs to increase drug distribution to liver, kidney, or muscle tissue.
Influence of single versus multiple actuations on the particle size distribution of beclometasone dipropionate metered-dose inhalers
Authors: Feddah M R , Davies N M 
Published: September 2003

Abstract
The particle size distributions of beclometasone dipropionate delivered from Becotide and Respocort inhalers after single and multiple actuations were investigated using the Andersen Mark II Cascade impactor and the drug was quantified using high performance liquid chromatography. The fine particle mass and the mass median aerodynamic diameter were calculated. An apparent increase in mass median aerodynamic diameter was observed when the number of actuations increased. In addition, the fine particle mass decreased as the number of actuations increased. When performing and analysing cascade impaction study data differences between single versus multiple actuations must be considered. Regulatory guidelines should be amended to stipulate the number of actuations to be loaded into devices used to evaluate the particle size distribution of inhaled aerosol products.
Delivery of an anticancer drug and a chemosensitizer to murine breast sarcoma by intratumoral injection of sulfopropyl dextran microspheres
Authors: Liu Zhi , Ballinger James R , Rauth Andrew M , Bendayan Reina , Wu Xiao Yu 
Published: September 2003

Abstract
Intratumoral injection of controlled-release microsphere formulations of anticancer compounds has the potential to selectively increase tumour exposure to drugs. This work aimed to evaluate the therapeutic effect and toxicity of microsphere formulations containing the anticancer drug, doxorubicin, in a murine tumour model. The effect of co-administration of verapamil, a P-glycoprotein modulator or chemosensitizer, was investigated. Initial in-vitro studies confirmed the ability of verapamil to enhance the accumulation of both doxorubicin and [99mTc]sestamibi, also a P-glycoprotein substrate, in EMT6 murine breast sarcoma cells and a doxorubicin-selected multidrug-resistant variant, EMT6/AR1.0. Ex-vivo studies using confocal microscopy demonstrated release of doxorubicin from microspheres and diffusion of the drug through tissue. For in-vivo studies, EMT6 and EMT6/AR1.0 cells were grown in BALB/c mice. Following intratumoral injection of doxorubicin-loaded microspheres, alone or in combination with verapamil-loaded microspheres, the tumour diameter was measured serially as an indication of therapeutic effect, while the weight, appearance, and behaviour of the mice were monitored as an indication of general toxicity. Intratumoral injections of doxorubicin-loaded microspheres were tolerated much better than systemic administration of equivalent drug concentrations. There was a modest (up to 34%) delay of tumour growth compared with groups receiving no treatment or blank microspheres. Co-injection of verapamil microspheres with doxorubicin microspheres produced a moderate increase in toxicity but no further delay in tumour growth. Controlled-release microsphere formulations of anticancer agents administered intratumorally were an efficient way to deliver high drug doses to the tumour with little systemic toxicity.
Evaluation of the radioprotective effect of Ageratum conyzoides Linn. extract in mice exposed to different doses of gamma radiation
Authors: Jagetia Ganesh Chandra , Shirwaikar Annie , Rao Shaival K , Bhilegaonkar Prasad M 
Published: September 2003

Abstract
The effect of various doses (0, 25, 50, 75, 100, 125, 150, 300, 600 and 900 mg kg−1) of the alcoholic extract of the plant Ageratum conyzoides Linn. (ACE), on the alteration of radiation-induced mortality in mice exposed to 10 Gy of gamma radiation was studied. The acute toxicity studies showed that the drug was non-toxic up to a dose of 3000 mg kg−1, the highest dose that could be tested for acute toxicity. Administration of ACE resulted in a dose-dependent decline in radiation-induced mortality up to a dose of 75 mg kg−1, the dose at which the highest number of survivors (70.83%) was observed. Thereafter, the number of survivors declined with increasing doses of ACE and a nadir was reached at 900 mg kg−1 ACE. Since the number of survivors was highest for 75 mg kg−1 ACE, this was considered the optimum dose for radioprotection and used in further studies in which mice were treated with 75 mg kg−1 ACE before exposure to 6, 7, 8, 9, 10 and 11 Gy of gamma radiation. The treatment of mice with 75 mg kg−1 ACE reduced the severity of symptoms of radiation sickness and mortality at all exposure doses, and a significant increase in survival was observed compared with the non-treated irradiated group. The ACE treatment effectively protected mice against the gastrointestinal as well as bone marrow related death, as revealed by the increased number of survivors at all irradiation doses. The dose reduction factor was found to be 1.3. To understand the mechanism of action, various doses of ACE were evaluated for their in-vitro scavenging action on 1,1-diphenyl-2-picrylhydrazyl (DPPH), a chemically stable free radical. ACE was found to scavenge DPPH radicals in a concentration-dependent manner, indicating that the radioprotection afforded by ACE may be in part due to the scavenging of reactive oxygen species induced by ionizing radiation.
AWD 12–281, a highly selective phosphodiesterase 4 inhibitor, is effective in the prevention and treatment of inflammatory reactions in a model of allergic dermatitis
Authors: Bäumer Wolfgang , Gorr Gilbert , Hoppmann Joachim , Ehinger Andreas M , Rundfeldt Chris , Kietzmann Manfred 
Published: September 2003

Abstract
AWD 12–281 (N-(3,5-dichloro-4-pyridinyl)-2-[1-(4-fluorobenzyl)-5-hydroxy-1H-indol-3-yl]-2-oxoacetamide), a phosphodiesterase 4 inhibitor, which is optimized for topical administration, was tested in a model of allergic dermatitis in mice. To obtain an allergic dermatitis, BALB/c mice were sensitized to toluene-2,4-diisocyanate (TDI). The allergic reaction was challenged by topical administration of TDI onto the mice ears. AWD 12–281 was tested for its anti-inflammatory potential by oral, intraperitoneal and topical administration. The phosphodiesterase 4 inhibitor, cilomilast (SB 207499), and/or the corticosteroid, diflorasone diacetate, were used as reference compounds. Given orally and intraperitoneally 2 h before as well as 5 and 24 h after TDI challenge, AWD 12–281 showed no, or only a transient inhibition of the allergen-induced ear swelling, whereas cilomilast significantly inhibited this ear swelling. Applied topically onto the ears before TDI challenge, AWD 12–281, cilomilast and diflorasone diacetate caused total inhibition of ear swelling 24 h after challenge, confirmed by a decrease of the pro-inflammatory cytokines interleukin-4, interleukin-6 and macrophage inflammatory protein-2. Administered topically after TDI challenge as therapeutic intervention, AWD 12–281 and diflorasone diacetate caused significant inhibition of ear swelling; cilomilast failed to do so. These results indicate that topically administered AWD 12–281 may be potent in the prevention and treatment of allergic/inflammatory skin diseases.
Effects of the aqueous extract from Salvia miltiorrhiza Bge on the pharmacokinetics of diazepam and on liver microsomal cytochrome P450 enzyme activity in rats
Authors: Jinping Qiao , Peiling Hou , Yawei Li , Abliz Zeper 
Published: September 2003

Abstract
The aim of this study was to determine the effects of the aqueous extract of Salvia miltiorrhiza Bge (danshen in Chinese) on the pharmacokinetics of diazepam and on liver microsomal cytochrome P450 enzyme activity in rats. Rats (n = 5) were pretreated with danshen extract (100 mg kg−1 per day, p.o.) for 15 consecutive days. Control rats (n = 5) received saline at the same time. Each rat was then administered a single oral dose of 15 mg kg−1 diazepam. The pharmacokinetic parameters of diazepam were significantly different between the two groups. In the danshen pretreated group, the maximum concentration of diazepam and the area under the plasma concentration–time curve were reduced to about 72.7% and 44.4%, respectively, while the total body clearance was markedly increased by 2-fold. To help explain the results, liver microsomal suspensions were obtained from rats that were randomly divided into the control group (n = 10), and the low- (20 mg kg−1 for 15 days, p.o., n = 10) and high-dose groups (100 mg kg−1 for 15 days, p.o., n = 10) pretreated with danshen extract. Compared with the control rats, the microsomal protein content, cytochrome P450 enzyme level and erythromycin N-demethylase activity of pretreated rats were significantly increased. These results indicate that danshen extract can stimulate the activity of cytochrome P450 isoforms, and changes in the pharmacokinetics of diazepam resulting from danshen extract are related to an increase in metabolic activity of cytochrome P450.
Concept, mechanisms and therapeutics of angiogenesis in cancer and other diseases
Authors: Pralhad Tayade , Madhusudan Saraf , Rajendrakumar Kale 
Published: September 2003

Abstract
Angiogenesis supports normal physiology as well as contributing to the progression of various diseases including cancer. Determination of the key role of angiogenesis in cancer has led to much optimism for the development of targeted drugs without cytotoxic side-effects. Currently, research in angiogenesis therapy is robust, with the discovery of a growing number of pro- and anti-angiogenic molecules. More time, however, is required to be able to elucidate the complex interactions among these molecules, how they affect vasculature and their functions in different environments. As we learn more about the molecular mechanisms of angiogenesis, a number of effective methods to treat cancer and other diseases will be developed.
In-vitro metabolism of the new anxiolytic agent, RWJ-50172, in rat hepatic S9 fraction and microbial transformation in fungi, Cunninghamella sp.
Authors: Wu Wu-Nan , McKown Linda A , Melton John L , Reitz Allen B 
Published: September 2003

Abstract
The in-vitro biotransformation of the anxiolytic agent, RWJ-50172 was studied after incubation with rat hepatic S9 fraction in the presence of an NADPH-generating system, and incubating with Cunninghamella echinulata in soy-bean medium. Unchanged RWJ-50172 (80% of the sample in rat; 86% in fungi) plus 6 metabolites (M1-M6) were profiled, quantified and tentatively identified on the basis of API-MS/MS data. The metabolic pathways for RWJ-50172 are proposed, and the four metabolic pathways are: pyrido-oxidation (pathway A), phenylhydroxylation (B), dehydration (C) and reduction (D). Pathway A formed hydroxy-pyrido-RWJ-50172 (M1, 10% of the sample in both rat and fungi) as the only major metabolite, which further dehydrated to form dehydro-RWJ-50172 in trace quantities in rat. Pathway B produced hydroxyphenyl-RWJ-50172 (M2) in small amounts (4%) in rat, and in conjunction with step A formed dihydroxy-RWJ-50172 as a trace metabolite in rat. Step D produced a minor benzimidazole-reduced metabolite in fungi. RWJ-50172 is substantially metabolized by this rat hepatic S9 fraction and fungi.
Nitric oxide is involved in the expression of neocortical spike-and-wave spindling episodes in DBA/2J mice
Authors: Capasso A , Bianchi A , Loizzo A 
Published: September 2003

Abstract
This study investigated the possible role of nitric oxide (NO) in the development of neocortical spike-and-wave spindling episodes (S&W) of DBA/2J mice. The administration of distilled water did not modify either the number or duration of S&W in DBA/2J mice during the whole recording period (240min). l-NG-nitro arginine methyl ester (L-NAME) (3–300 μg/mouse, i.c.v.) dose-dependently reduced the S&W of DBA/2J mice. This effect appeared 30 min after drug administration and lasted for the duration of the recording period (240min). In addition, L-NAME treatment did not induce significant alterations of stereotyped behaviour such as licking, sniffing, chewing or tremors of the head and body and behavioural excitability, whereas the electroencephalogram desynchronized pattern was also significantly reduced. By contrast d-NG-nitro arginine methyl ester at the same doses did not affect S&W of mice. The inhibitory effect of L-NAME on S&W of mice was dose-dependently reversed by l-arginine (L-ARG, 3–300 μg/mouse, i.c.v.) but not by d-arginine. Finally, glyceryl trinitrate on its own (3–300 μg/mouse, i.c.v.) significantly increased the S&W of mice and it was also able to reverse the inhibition on S&W of mice operated by L-NAME. These results provide evidence that NO may play a significant role in the development of brain excitability.