bluuebunny/crossref_metadata_2025_split huggingface dataset:
TGF‐β Signaling in Colon Cancer Cells
Authors: Li Fazhi , Cao Yanna , Townsend Courtney M. , Ko Tien C. 
Published: February 2005

AbstractTransforming growth factor‐betas (TGF‐βs), cytokines expressed in the colon, play important roles as tumor suppressors and tumor promoters during colorectal carcinogenesis. TGF‐β signaling pathway involves activation of Smad2 and Smad3 by the type I receptor and formation of Smad2/3/4 heteromeric complexes that enter the nucleus to regulate transcription. Most human colorectal cancers are resistant to the tumor suppressor effects of TGF‐β, and a subset of human colorectal cancers have mutations in Smad2 and Smad4. The purpose of this study was to determine whether Smads are required for TGF‐β signaling in colon cancer cells. First, we selected a colon cancer cell line (MC‐26) that has a functional TGF‐β signaling pathway. We found that MC‐26 cells expressed Smad2, Smad3, and Smad4 mRNAs by reverse transeription‐polymerase chain reaction and confirmed that the TGF‐β signaling pathway is functional using a transient transfection assay with 3TP‐Lux reporter plasmid. TGF‐β also inhibited cell growth and induced apoptosis in MC‐26 cells. When MC‐26 cells were transiently transfected with dominant‐negative carboxyl‐terminal truncation mutants of Smad2, Smad3, and Smad4, TGF‐β‐induced 3TP‐Lux reporter activity was significantly reduced, suggesting that Smad2, Smad3, and Smad4 are attractive novel therapeutic targets for regulating TGF‐β signaling in colorectal cancers. Because MC‐26 cells express TGF‐β activated Smads, have a functional TGF‐β signaling pathway, and are sensitive to the growth inhibitory and apoptotic effects of TGF‐β, they can serve as an excellent model to examine TGF‐β signaling in colorectal cancers.
GABAB receptor modulators potentiate baclofen‐induced depression of dopamine neuron activity in the rat ventral tegmental area
Authors: Chen Ying , Phillips Keith , Minton Gareth , Sher Emanuele 
Published: February 2005

2,6‐Di‐tert‐butyl‐4‐(3‐hydroxy‐2,2‐dimethyl‐propyl)‐phenol (CGP7930) is a recently reported positive allosteric modulator of γ‐aminobutyric acid (GABA)B receptors. In this study, we assessed the ability of CGP7930 to modulate the baclofen‐induced depression of dopamine (DA) neuron activity via the activation of GABAB receptors in the ventral tegmental area in rat midbrain slices.
The selective GABAB receptor agonist, baclofen, depressed the spontaneous firing rate of DA neurons in a concentration‐dependent manner (EC50=0.27 μM, n=11). CGP7930 (30 μM) significantly (P<0.05) shifted the baclofen concentration–response curve to the left (EC50=0.15 μM, n=5). The effects of baclofen alone or baclofen coapplied with CGP7930 were fully blocked by 1 μM (2S)‐3‐[[(1S)‐1‐(3,4‐dichloropheny)ethyl]amino‐2‐hydroxypropyl] (phenylmethyl) phosphinic acid (CGP55845), a potent and selective GABAB receptor antagonist.
In similar experiments, N‐[3,3‐diphenylpropyl]‐α‐methylbenzylamine (fendiline) (30 or 50 μM), a compound shown to potentiate GABAB receptor‐mediated cortical hyperpolarisation, also significantly enhanced the inhibitory effect of baclofen.
It is therefore concluded that the recently reported GABAB receptor modulators, CGP7930 and fendiline, can enhance GABAB receptor‐mediated depression of DA neuronal activity. This finding suggests a therapeutic potential for GABAB potentiators for the treatment of diseases associated with a hyperfunctional mesocorticolimbic system.

British Journal of Pharmacology (2005) 144, 926–932. doi:10.1038/sj.bjp.0706100
High doses of simvastatin upregulate dopamine D1 and D2 receptor expression in the rat prefrontal cortex: possible involvement of endothelial nitric oxide synthase
Authors: Wang Qing , Ting Wee Lee , Yang Hongyuan , Wong Peter T‐H 
Published: February 2005

This study aims to investigate whether or not long‐term statin treatment causes upregulation of D1 and D2 receptor gene expression with concomitant increase in endothelial nitric oxide synthase (eNOS) expression in Sprague–Dawley rats.
Serum triglyceride levels were dose dependently reduced in the simvastatin‐treated rats reaching statistical significance at the highest dose (49% reduction), while pravastatin caused similar effects (52%) at the same dose. Cholesterol levels remained unchanged in both groups at all doses.
Simvastatin, 10 or 30 mg kg−1 day−1, increased D1 and D2 receptor expressions in the prefrontal cortex. Similar upregulation was observed neither with simvastatin in the striatum nor with pravastatin in both brain regions.
Simvastatin (10 mg kg−1 day−1) also increased eNOS expression in the prefrontal cortex but not neuronal NOS or inducible NOS.
D1 receptor activation by chloro‐APB (5 μM) increased cAMP levels in synaptosomes prepared from the prefrontal cortex of control and simvastatin‐treated rats by 88 and 285%, respectively. This effect was markedly attenuated by the selective D1 antagonist SCH‐23390 (25 μM).
D2 receptor activation by quinpirole (5 μM) had no effect on the basal cAMP levels in synaptosomes prepared from the prefrontal cortex of control and simvastatin‐treated rats, while the same concentration of quinpirole completely abolished the D1 receptor‐mediated increase.
These results suggest that lipophilic statins can alter dopaminergic functions in the prefrontal cortex possibly via a central mechanism. The possibility of a nitric oxide mechanism involving eNOS requires further investigation.

British Journal of Pharmacology (2005) 144, 933–939. doi:10.1038/sj.bjp.0706106
Neuritic regeneration and synaptic reconstruction induced by withanolide A
Authors: Kuboyama Tomoharu , Tohda Chihiro , Komatsu Katsuko 
Published: February 2005

We investigated whether withanolide A (WL‐A), isolated from the Indian herbal drug Ashwagandha (root of Withania somnifera), could regenerate neurites and reconstruct synapses in severely damaged neurons. We also investigated the effect of WL‐A on memory‐deficient mice showing neuronal atrophy and synaptic loss in the brain. Axons, dendrites, presynapses, and postsynapses were visualized by immunostaining for phosphorylated neurofilament‐H (NF‐H), microtubule‐associated protein 2 (MAP2), synaptophysin, and postsynaptic density‐95 (PSD‐95), respectively.
Treatment with Aβ(25–35) (10 μM) induced axonal and dendritic atrophy, and pre‐ and postsynaptic loss in cultured rat cortical neurons. Subsequent treatment with WL‐A (1 μM) induced significant regeneration of both axons and dendrites, in addition to the reconstruction of pre‐ and postsynapses in the neurons.
WL‐A (10 μmol kg−1 day−1, for 13 days, p.o.) recovered Aβ(25–35)‐induced memory deficit in mice. At that time, the decline of axons, dendrites, and synapses in the cerebral cortex and hippocampus was almost recovered.
WL‐A is therefore an important candidate for the therapeutic treatment of neurodegenerative diseases, as it is able to reconstruct neuronal networks.

British Journal of Pharmacology (2005) 144, 961–971. doi:10.1038/sj.bjp.0706122
The immunosuppressive drugs cyclosporin A and tacrolimus inhibit membrane depolarization‐induced CREB transcriptional activity at the coactivator level
Authors: Oetjen Elke , Thoms Kai‐Martin , Laufer Yvonne , Pape Daniela , Blume Roland , Li Pingfeng , Knepel Willhart 
Published: February 2005

Cyclosporin A and tacrolimus are clinically important immunosuppressive drugs directly targeting the transcription factor nuclear factor of activated T cells (NFAT). Through inhibition of calcineurin phosphatase activity they block the dephosphorylation and thus activation of NFAT. Cyclosporin A and tacrolimus also inhibit other calcineurin‐dependent transcription factors including the ubiquitously expressed cAMP response element‐binding protein (CREB). Membrane depolarization by phosphorylating CREB on Ser119 leads to the recruitment of its coactivator CREB‐binding protein (CBP) that stimulates initiation of transcription.
It was unknown at what step in CREB‐mediated transcription cyclosporin A and tacrolimus interfere.
In transient transfection experiments, using GAL4‐CREB fusion proteins and a pancreatic islet β‐cell line, cyclosporin A inhibited depolarization‐induced activation of CREB proteins which carried various deletions or mutations throughout their sequence providing no evidence for the existence of a distinct CREB domain conferring cyclosporin A sensitivity. In a mammalian two‐hybrid assay, cyclosporin A did not inhibit Ser119‐dependent interaction of CREB with its coactivator CBP.
Using GAL4‐CBP fusion proteins, cyclosporin A inhibited depolarization‐induced CBP activity, with cyclosporin A‐sensitive domains mapped to both the N‐ (aa 1–451) and C‐terminal (aa 2040–2305) ends of CBP. The depolarization‐induced transcriptional activity of the CBP C‐terminus was enhanced by overexpression of calcineurin and was inhibited by cyclosporin A and tacrolimus in a concentration‐dependent manner with IC50 values (10 and 1 nM, respectively) consistent with their known IC50 values for inhibition of calcineurin.
These data suggest that, in contrast to NFAT, cyclosporin A and tacrolimus inhibit CREB transcriptional activity at the coactivator level.

British Journal of Pharmacology (2005) 144, 982–993. doi:10.1038/sj.bjp.0706127
Antisecretory actions of a novel vasoactive intestinal polypeptide (VIP) antagonist in human and rat small intestine
Authors: Banks Matthew R , Farthing Michael J G , Robberecht Patrick , Burleigh David E 
Published: February 2005

Vasoactive intestinal peptide (VIP) has been demonstrated in intestinal mucosal neurones and elicits chloride secretion from enterocytes. These findings have led to the proposal that VIP is a secretomotor neurotransmitter. Confirmation of such a role may now be possible with the development of PG 97–269, a high‐affinity, selective antagonist of VIP type 1 (VPAC1) receptor, which is expressed by gut epithelial cells. We have evaluated the VIP antagonism and antisecretory potential of this novel compound using in vitro and in vivo models of intestinal secretion.
Monolayers of the human colonic cell line (T84) and muscle‐stripped preparations of rat jejunum and human ileum were set up in Ussing chambers for recording of transepithelial resistance and short‐circuit current. Ussing chambers were modified to allow electrical stimulation of mucosal neurones. Effects of PG 97–269 on enterotoxin‐induced secretion were investigated in perfused rat jejunum in vivo.
PG 97–269 competitively antagonised VIP in T84 monolayers. In rat jejunum and human ileum, responses to VIP were inhibited as were responses of rat jejunum to electrical stimulation of mucosal neurons.
In perfused rat jejunum, PG 97–269 abolished the effects of VIP on fluid and electrolyte transport and attenuated cholera toxin and Escherichia coli heat labile toxin‐induced net fluid and electrolyte secretion.
PG 97–269 is a competitive antagonist of enterocyte VIP receptors and effectively inhibits responses of rat and human intestinal mucosa to VIP. Antagonism of secretory responses to electrical stimulation of mucosal neurons and lumenal application of enterotoxins imply a secretory role for VIP in these processes.

British Journal of Pharmacology (2005) 144, 994–1001. doi:10.1038/sj.bjp.0706128
Pentamidine reduces hERG expression to prolong the QT interval
Authors: Cordes Jason S , Sun Zhuoqian , Lloyd David B , Bradley Jenifer A , Opsahl Alan C , Tengowski Mark W , Chen Xian , Zhou Jun 
Published: February 2005

Pentamidine, an antiprotozoal agent, has been traditionally known to cause QT prolongation and arrhythmias; however, its ionic mechanism has not been illustrated.
In a stable HEK‐293 cell line, we observed a concentration‐dependent inhibition of the hERG current with an IC50 of 252 μM.
In freshly isolated guinea‐pig ventricular myocytes, pentamidine showed no effect on the L‐type calcium current at concentrations up to 300 μM, with a slight prolongation of the action potential duration at this concentration.
Since the effective concentrations of pentamidine on the hERG channel and APD were much higher than clinically relevant exposures (∼1 μM free or lower), we speculated that this drug might not prolong the QT interval through direct inhibition of IKr channel. We therefore incubated hERG‐HEK cells in 1 and 10 μM pentamidine‐containing media (supplemented with 10% serum) for 48 h, and examined the hERG current densities in the vehicle control and pentamidine‐treated cells.
In all, 36 and 85% reductions of the current densities were caused by 1‐ and 10‐μM pentamidine treatment (P<0.001 vs control), respectively. A similar level of reduction of the hERG polypeptides and a reduced intensity of the hERG protein on the surface membrane in treated cells were observed by Western blot analysis and laser‐scanning confocal microscopy, respectively.
Taken together, our data imply that chronic administration of pentamidine at clinically relevant exposure reduces the membrane expression of the hERG channel, which may most likely be the major mechanism of QT prolongation and torsade de pointes reported in man.

British Journal of Pharmacology (2005) 145, 15–23. doi:10.1038/sj.bjp.0706140
The mutation Y1206S increases the affinity of the sulphonylurea receptor SUR2A for glibenclamide and enhances the effects of coexpression with Kir6.2
Authors: Stephan Damian , Stauß Eva , Lange Ulf , Felsch Holger , Löffler‐Walz Cornelia , Hambrock Annette , Russ Ulrich , Quast Ulrich 
Published: February 2005

ATP‐sensitive K+ channels (KATP channels) are tetradimeric complexes of inwardly rectifying K+ channels (Kir6.x) and sulphonylurea receptors (SURs). The SURs SUR2A (cardiac) and SUR2B (smooth muscle) differ only in the last 42 amino acids. In SUR2B, the mutation Y1206S, located at intracellular loop 8, increases the affinity for glibenclamide (GBC) about 10‐fold. Here, we examined whether the mutation Y1206S in SUR2A had effects similar to those in SUR2B.
GBC bound to SUR2A with KD=20 nM; the mutation increased affinity ∼5 ×.
In cells, coexpression of SUR2A with Kir6.2 increased the affinity for GBC∼3 ×; with the mutant, the increase was 9 ×.
The mutation did not affect the affinity of SUR2A for openers; coexpression with Kir6.2 reduced opener affinity of wild‐type and mutant SUR2A by about 2 ×.
The negative allosteric interaction between the opener, P1075, and GBC at wild‐type and mutant SUR2A was markedly affected by the presence of MgATP and by coexpression with Kir6.2.
In inside‐out patches, GBC inhibited the wild‐type Kir6.2/SUR2A and 2B channels with IC50 values of 27 nM; the mutation shifted the IC50 values to ∼1 nM.
The data show that the mutation Y1206S increased the affinity of SUR2A for GBC and modulated the effects of coexpression. Overall, the changes were similar to those observed with SUR2B(Y1206S), suggesting that the differences in the last 42 carboxy‐terminal amino acids of SUR2A and 2B are of limited influence on the binding of GBC and P1075 to the SUR2 isoforms.

British Journal of Pharmacology (2005) 144, 1078–1088. doi:10.1038/sj.bjp.0706142
Protein trafficking abnormalities: a new mechanism in drug‐induced long QT syndrome
Authors: Eckhardt Lee L , Rajamani Sridharan , January Craig T 
Published: February 2005

Drug induced long QT syndrome (LQTS) can lead to cardiac arrhythmias and sudden death, and has emerged as a worldwide problem. Most drugs that cause this are thought to directly block a specific cardiac ion channel (KCNH2 or hERG) that carries the rapidly activating delayed rectifier potassium current, IKr. In this issue of the British Journal of Pharmacology, evidence is presented to support a new mechanism for causing drug induced LQTS. The drug pentamidine, at near therapeutic concentrations that do not cause direct KCNH2 channel block, disrupts normal KCNH2 channel protein processing and maturation to reduce its surface membrane expression. This indirect mechanism for reducing IKr is novel, and whether other drugs may cause similar protein trafficking abnormalities is largely unknown.British Journal of Pharmacology (2005) 145, 3–4. doi:10.1038/sj.bjp.0706143
Hepatic pharmacokinetics of taurocholate in the normal and cholestatic rat liver
Authors: Hung Daniel Y , Siebert Gerhard A , Chang Ping , Roberts Michael S 
Published: February 2005

The disposition kinetics of [3H]taurocholate ([3H]TC) in perfused normal and cholestatic rat livers were studied using the multiple indicator dilution technique and several physiologically based pharmacokinetic models.
The serum biochemistry levels, the outflow profiles and biliary recovery of [3H]TC were measured in three experimental groups: (i) control; (ii) 17α‐ethynylestradiol (EE)‐treated (low dose); and (iii) EE‐treated (high dose) rats. EE treatment caused cholestasis in a dose‐dependent manner.
A hepatobiliary TC transport model, which recognizes capillary mixing, active cellular uptake, and active efflux into bile and plasma described the disposition of [3H]TC in the normal and cholestatic livers better than the other pharmacokinetic models.
An estimated five‐ and 18‐fold decrease in biliary elimination rate constant, 1.7‐ and 2.7‐fold increase in hepatocyte to plasma efflux rate constant, and 1.8‐ and 2.8‐fold decrease in [3H]TC biliary recovery ratio was found in moderate and severe cholestasis, respectively, relative to normal.
There were good correlations between the predicted and observed pharmacokinetic parameters of [3H]TC based on liver pathophysiology (e.g. serum bilirubin level and biliary excretion of [3H]TC). In conclusion, these results show that altered hepatic TC pharmacokinetics in cholestatic rat livers can be correlated with the relevant changes in liver pathophysiology in cholestasis.

British Journal of Pharmacology (2005) 145, 57–65. doi:10.1038/sj.bjp.0706148
Noradrenaline and extracellular nucleotide cotransmission involves activation of vasoconstrictive P2X1,3‐ and P2Y6‐like receptors in mouse perfused kidney
Authors: Vonend Oliver , Stegbauer Johannes , Sojka Johann , Habbel Sina , Quack Ivo , Robaye Bernard , Boeynaems Jean‐Marie , Rump Lars Christian 
Published: February 2005

Nucleotides like ATP and UTP act as potent extracellular signalling molecules. Released from sympathetic nerve endings as cotransmitters of noradrenaline or paracrine from nonexcitatory cells, they activate specific receptors (ion‐gated P2X1–7 and G‐protein‐coupled P2Y1,2,4,6,11–15). Which of these subtypes, however, are able to modulate vasoconstriction in the kidney is unclear.
Wild‐type‐ and P2Y4‐receptor‐deficient mice kidneys were isolated and perfused with Krebs–Henseleit solution. Pressor responses to renal nerve stimulations (RNS) and added drugs were recorded. Release of endogenous noradrenaline was measured by HPLC.
RNS (1–15 Hz) induced a frequency‐dependent increase in the perfusion pressor (14.2±5.1–67.3±6.9 mmHg) and noradrenaline release (1.4±0.3–24.2±3.4 ng g−1 kidney).
Pressor responses to RNS were not (1–2 Hz) or only partially (5–15 Hz) blocked by the α‐adrenoceptor antagonist phentolamine (1 μM). Combination of phentolamine and the P2‐receptor blocker PPADS (5 μM) prevented RNS‐induced pressor responses. The P2X1,3‐receptor selective antagonist NF279 (10 μM) reduced RNS‐induced pressor responses in a frequency‐dependent manner.
Perfusion of ATP, ADP, UTP, UDP and α,β‐meATP concentration dependently increased perfusion pressor with the following rank order of potency α,β‐meATP>ADP≈ATP≈UDPUTP. NF279 (10 μM) reduced α,β‐meATP‐ (0.1 μM) (21.7±3.9% of control) but not UTP‐ (0.3 μM) (102.6±15.3% of control) induced pressor responses. No differences in nucleotide‐induced effects were detected among wild‐type and P2Y4‐receptor knockout mice.
Continuous perfusion of α,β‐meATP (0.01 μM) potentiated UTP‐, UDP‐ and ATP‐γS‐induced pressor responses.
Neuronally and paracrine‐released nucleotides evoked renal vasoconstriction by activation of P2X1,3‐ and P2Y6‐like receptors in mice. Pretreatment with the P2X1,3‐receptor agonist α,β‐meATP potentiated P2Y6‐like receptor‐mediated vasoconstrictions.

British Journal of Pharmacology (2005) 145, 66–74. doi:10.1038/sj.bjp.0706151
New anticoagulants: beyond heparin, low‐molecular‐weight heparin and warfarin
Authors: Bates Shannon M , Weitz Jeffrey I 
Published: February 2005

The limitations of traditional anticoagulants, heparin and warfarin, have prompted the development of new anticoagulant drugs for prevention and treatment of both venous and arterial thromboembolism. After a brief review of thrombogenesis and its regulation, this paper focuses on new anticoagulant agents in more advanced stages of clinical testing.British Journal of Pharmacology (2005) 144, 1017–1028. doi:10.1038/sj.bjp.0706153
Cyclic GMP, sodium nitroprusside and sodium azide reduce aqueous humour formation in the isolated arterially perfused pig eye
Authors: Shahidullah Mohammad , Yap Maurice , To Chi‐ho 
Published: February 2005

The effect of nitric oxide (NO) on aqueous humour formation (AHF) and intraocular pressure (IOP) was studied using NO donors, sodium azide (AZ) and sodium nitroprusside (SNP).
Using the porcine arterially perfused eye preparation, drug effects on AHF and IOP were measured by fluorescein dilution and manometry, respectively. Perfusion pressure of the ocular vasculature was also monitored using digital pressure transducer and pen recorder.
L‐Arginine (1.0 mM), a precursor of NO, but not D‐arginine (1.0 mM), the inactive analogue, produced a significant reduction in AHF (28.5%) and IOP (21.1%). L‐NAME (L‐nitro‐L‐arginine) (10–100 μM), an NO synthase inhibitor, had no effect on AHF and IOP. However, L‐NAME (100 μM) completely reversed L‐arginine's effect.
AZ and SNP reduced the AHF and IOP dose‐dependently. AZ at 100 nM, 1 and 10 μM reduced AHF by 26.0, 39.7 and 51.7% and IOP by 10.8, 17.3 and 24.0%, respectively. SNP at 1, 10 and 100 μM reduced the AHF by 6.0, 24.2 and 35.4% and IOP by 3.5, 9.5 and 15.5%, respectively. 8‐pCPT‐cGMP (8‐para‐chlorophenyl‐thioguanosine‐3′,5′‐cyclic guanosine monophosphate, 10 μM), a cGMP analogue, also reduced the AHF (34.9%) and IOP (15.9%).
The effects of AZ and SNP on the AHF and IOP were blocked by a soluble guanylate cyclase inhibitor ODQ (10 μM), whereas ODQ alone or combined with 8‐pCPT‐cGMP had no effect on the AHF and IOP.
None of the drugs had any significant effect on ocular vasculature.
The reduction of the AHF and IOP in the arterially perfused pig eye by nitrovasodilators is likely to involve the NO‐cGMP pathway.

British Journal of Pharmacology (2005) 145, 84–92. doi:10.1038/sj.bjp.0706156