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PubMed1994

Antagonists of 5-HT4 receptor-mediated responses in adult hippocampal neurons.

The study of serotonin-4 (5-HT4) receptors in the central nervous system has been hindered by the lack of effective, selective antagonists. However, recently, several novel compounds have been synthesized and shown to act as antagonists at 5-HT4 receptors in smooth muscle and embryonic neurons in culture. In the present study, intracellular electrophysiological recordings were used to test the effects of three of these compounds: endo-8-methyl-8-azabicyclo[3.2.1]oct-3-yl-2,3-dihydro-6-methoxy- 2-oxo-1H-benzimidazole-1-carboxylate (DAU 6285), [1-[2-(methylsulfonylamino)ethyl]-4-piperidinyl]methyl 1-methyl-1H-indole-3-carboxylate (GR 113808) and 2-diethylaminoethyl-(2-methoxy-4-amino-5-chloro) benzoate (SDZ 205-557) on the 5-HT4 reduction of the afterhyperpolarization seen in adult CA1 hippocampal neurons in brain slices. GR 113808, SDZ 205-557 and DAU 6285 all functioned as competitive antagonists at these 5-HT4 receptors. Although all three compounds tested acted as effective antagonists, they differed considerably in potency. When the potency of these antagonists at the 5-HT4 receptor that mediates the reduction of the afterhyperpolarization was compared with that observed for 5-HT4 receptors in biochemical and binding assays, an excellent correlation was observed. Among the antagonists tested, GR 113808 was the most potent (pA2 = GR 113808 > SDZ 205-507 > DAU 6285). It exhibited an apparent affinity for the 5-HT4 receptors in the low nanomolar range but did not antagonize 5-HT1A, beta-adrenergic or muscarinic receptor-mediated responses when applied at concentrations two orders of magnitude higher.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminobenzoic Acid↗
PubMed1994

[3H]RS-23597-190, a potent 5-hydroxytryptamine4 antagonist labels sigma-1 but not sigma-2 binding sites in guinea pig brain.

Recent findings have suggested a relationship between 5-hydroxytryptamine (5-HT)4 receptors and sigma binding sites. To test this idea, the affinity of 5-HT4 receptor ligands for sigma binding sites was examined. In contrast to the 5-HT4 receptor ligands BIMU-1 [endo-N-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-2,3- dihydro-3-ethyl-2-oxo-1H-benzimidazole-1-carboxamide hydrochloride] and BIMU-8 [endo-N-(8-methyl-8-azabicyclo[3.2.1]oct-3- yl)-2,3-dihydro-(1-methyl)ethyl-2-oxo-1H-benzamidazole-1-carbox ami de hydrochloride], DAU 6215 ]N-(endo-8-methyl-8-azabicyclo[3.2.1.]oct-3-yl)-2,3-dihydro-2-oxo-1H- benzimidazole-1-carboxamide hydrochloride], 5-HT and 5-methoxytryptamine had low affinity for sigma binding sites (pKi < 6). Conversely, the sigma ligands haloperidol and pentazocine had low affinity for 5-HT4 receptors. Thus, no relationship was found between the affinity of ligands at 5-HT4 receptors and sigma binding sites. However, one potent 5-HT4 receptor antagonist, RS-23597-190 [3-(piperidine-1-yl)propyl-4-amino-5-chloro-2-methoxybenzoate hydrochloride], had high affinity for sigma-1 (pKi = 8.4) but not sigma-2 (pKi = 6.2) binding sites. [3H]RS-23597-190 bound to a saturable site with the pharmacology of a sigma-1 binding site: (pIC50) haloperidol (9.0) > (+)-pentazocine (8.8) > (+)-3-(hydroxyphenyl)-N-(1-propyl)piperidine (8.2) > 1,3-di-o-tolyl-guanidine (8.0) > (-)-pentazocine (7.8) = (+)-SKF 10,047 [N-allylnormetazocine] > (-)-SKF 10,047 (6.2) > BIMU-1 (5.3) > 5-HT and 5-methoxytryptamine. The distribution of [3H]RS-23597-190 binding sites was similar to that described for other sigma radioligands, with the greatest binding densities in cranial nerve nuclei, the tegmental nucleus and in the mamillary nucleus. In contrast to (+)-3-(hydroxyphenyl)-N-(1-propyl)piperidine, [3H]RS-23597-190 binding was not allosterically modulated by phenytoin. These studies do not support the notion of an obvious relationship between sigma and 5-HT4 receptors, but they provide additional insight into the structure/affinity relationship of ligands at specific sigma binding sites, and they uncover a novel sigma-1 receptor ligand whose binding is insensitive to the action of phenytoin.

Aminobenzoates↗
PubMed1994

[Reexamination of BT-PABA test (PFD)--on the substrate specificity for pancreatic chymotrypsin in vivo].

It is widely believed that BT-PABA is a specific substrate for pancreatic chymotrypsin, and based on this concept, BT-PABA test is used to evaluate the exocrine pancreatic function. But this test shows unusual clinical results particularly in patients after total pancreatectomy. In order to reevaluate the specificity of BT-PABA for chymotrypsin, we investigated the intestinal influence on this substrate in in vivo and in vitro studies using mongrel dogs under the conditions of complete absence of pancreatic juice in the alimentary tract. In vivo study showed that serum PABA increased after BT-PABA administration in the models of complete absence of pancreatic chymotrypsin and in vitro study demonstrated BT-PABA splitting activity fo jejunum and ileum mucosal homogenate which increased after total pancreatectomy. Hence, we concluded that BT-PABA is not a specific substrate for pancreatic chymotrypsin in vivo in human and in dog.

4-Aminobenzoic Acid↗
PubMed1993

13C-labeled trioctanoin breath test for exocrine pancreatic function test in patients after pancreatoduodenectomy.

To assess exocrine pancreatic function in patients before and after pancreatoduodenectomy (PD), we used the breath test, with nonradioactive 13C-labeled trioctanoin, in 14 patients before pancreatic resection because of localized pancreatic mass (preop-PD group), and in 13 patients who had undergone pancreatoduodenectomy more than 5 yr before (post-PD group). The results were compared with those of the secretin test, N-benzolyl-L-tyrosyl-p-amino benzoic acid (BT-PABA) test, and fecal chymotrypsin. Means +/- SD and frequencies of low values of the recovery of the breath test were 42.0 +/- 3.4%, 0/5 in the control; 24.2 +/- 10.5%, 14/14 in the preop-PD group; and 18.6 +/- 8.0, 13/13 in the post-PD group. The overall sensitivities in the preop- and post-PD groups were 100% for the recovery and 93% for the maximal mass ratio of the breath test, 89% for the secretin test, 67% for the BT-PABA test, and 64% for fecal chymotrypsin. The recovery of the breath test correlated significantly with the duodenal outputs of lipase, amylase, and chymotrypsin, and was not affected in patients with obstructive jaundice or with low D-xylose absorption. The breath test is as sensitive as the secretin test, more reliable than the conventional tubeless tests, and is available to follow up the exocrine pancreatic function before and after pancreatoduodenectomy.

4-Aminobenzoic Acid↗
PubMedDate not supplied

[Amben and galascorbin in the combined treatment of ulcerative-necrotic lesions of the oral mucosa].

Clinical efficacy of ambene-galascorbic solution was studied in 58 patients with ulcerative necrotic lesions of the buccal mucosa. The results were assessed by clinical and laboratory parameters. Local application of ambene-galascorbic complex was found to be safe and effective in patients with ulcerative necrotic lesions of the buccal mucosa of various origin.

4-Aminobenzoic Acid↗
PubMed1993

Cyclosporin and carnitine prevent the anoxic death of cultured hepatocytes by inhibiting the mitochondrial permeability transition.

Cyclosporin A (CyA) and L-carnitine (LC) prevented the killing of cultured hepatocytes by anoxia and rotenone but not by cyanide. Neither CyA nor LC affected the rate or extent of the loss of the mitochondrial membrane potential or the rate or extent of the depletion of ATP. Atractyloside blocked the ability of both CyA and LC to protect, and D-carnitine antagonized the effect of LC but not that of CyA. Cell killing by cyanide was prevented when the phospholipase A2 inhibitor butacaine was added together with CyA. Butacaine by itself had no effect on cell killing. In a swelling assay with isolated rat liver mitochondria having a low calcium content, phenylarsine oxide or palmitoyl-CoA induced the inner membrane permeability transition when electron transport was inhibited by rotenone or cyanide. CyA prevented the permeability transition with rotenone but not with cyanide, and atractyloside reversed the effect of CyA. LC prevented the permeability transition occurring with palmitoyl-CoA plus rotenone but not with palmitoyl-CoA plus cyanide. Atractyloside and D-carnitine antagonized the protective effect of LC. Inhibition of the cyanide-dependent permeability transition in isolated liver mitochondria required the presence of both CyA and butacaine. These data document the close correlation between the effect of CyA and LC on the response of cultured hepatocytes to inhibition of mitochondrial electron transport and their ability to prevent the permeability transition in isolated mitochondria. It is concluded that the ability of CyA and LC to protect cultured hepatocytes is a consequence of their ability to prevent the mitochondrial permeability transition, indicating that this event is likely to be causally linked to the genesis of irreversible injury. Thus, cell death with anoxia or inhibitors of electron transport is related to a mitochondrial alteration by a mechanism that is independent of the maintenance of a membrane potential or cellular stores of ATP.

4-Aminobenzoic Acid↗
PubMed1993

SC-53606, a potent and selective antagonist of 5-hydroxytryptamine4 receptors in isolated rat esophageal tunica muscularis mucosae.

(1-S,8-S)-N-[(hexahydro-1H-pyrrolizin-1-yl)methyl]-6-chloroimi+ ++- dazo[1,2-a]pyridine-8-carboxamide hydrochloride (SC-53606) acts as an antagonist of 5-hydroxytryptamine4 (5-HT4) receptor-mediated relaxation of carbachol-induced contractions in rat esophageal tunica muscular mucosae, but does not possess 5-HT4 agonist activity. SC-53606 demonstrated a pA2 value against 5-HT in this tissue of 7.91 +/- 0.08 (Ki = 12.3 +/- 1.17 nM). Similar pA2 values of 7.68 +/- 0.06, 7.67 +/- 0.06 and 7.63 +/- 0.05 were determined for the synthetic 5-HT4 receptor agonists SC-53116, 5-methoxytryptamine and renzapride, respectively. In addition, slopes of Schild plots for antagonism of these four agonists by SC-53606 were 1.07 +/- 0.02, 0.98 +/- 0.03, 1.04 +/- 0.02 and 0.96 +/- 0.06, respectively, and did not deviate from unity. The pA2 values for 5-HT4 antagonism against 5-HT were determined to be 6.80 +/- 0.09 for tropisetron and 7.36 +/- 0.08 for 2-methoxy-4-amino-S- chlorobenzoic acid-2-(diethylamino)ethyl ester SDZ 205-557), indicating that SC-53606 is more a potent 5-HT4 antagonist than either of the reference antagonists. Radioligand binding studies also demonstrated that SC-53606 is a selective antagonist with more affinity for 5-HT4 than for other 5-HT receptors. Displacement of radioligand binding from 5-HT1 and 5-HT2 receptors by SC-53606 was less than 50% at a 10 microM concentration. Similarly, SC-53606 displayed little binding affinity at alpha 1, alpha 2 and beta adrenergic, dopamine1, dopamine2 and muscarinic cholinergic receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminobenzoic Acid↗
PubMed1993

[BT-PABA/xylose test in the cat?].

The BT-PABA/Xylose test was used in 10 healthy cats and 49 cats with chronic diarrhea. In seven cats the test was performed three times in order to investigate individual variability. There was a statistically significant difference between the control group and the patients in the mean peak concentration of xylose, but no difference between groups of different diseases. The mean peaks of PABA were not significantly different between the control group and the patient group. Due to high individual variation in healthy cats the BT-PABA/Xylose test cannot be considered to be a useful test in feline diagnosis.

4-Aminobenzoic Acid↗
PubMed1995

A noninvasive stable-isotope method to simultaneously assess pancreatic exocrine function and small bowel absorption.

OBJECTIVE: To determine if a single-step noninvasive stable isotope method of assessing digestive function could separate normal subjects from subjects with pancreatic insufficiency (maldigestion) or small bowel dysfunction (malabsorption) and to see if subjects with maldigestion could be simultaneously separated from subjects with malabsorption. METHODS: Forty (40) normal volunteers, 18 adults with cystic fibrosis and four adults with celiac sprue, ingested a liquid test meal along with bentiromide, [13C6]PABA, and xylose (PABAX test). Serum was collected at 1 h and analyzed for PABA, [13C6]PABA, and xylose by stable isotope dilution methods using gas chromatography mass spectrometry. RESULTS: All subjects with cystic fibrosis had abnormal pancreatic function test results, whereas three of four adults with sprue had normal values of pancreatic function. All subjects with sprue had abnormal small bowel absorption tests, whereas all adults with cystic fibrosis had apparently normal intestinal function. CONCLUSION: The one-step, 1-h PABAX test can reliably separate normal subjects from those with either maldigestion or malabsorption and can also separate subjects with maldigestion from those with malabsorption.

4-Aminobenzoic Acid↗
PubMed1996

LY353433, a potent, orally effective, long-acting 5-HT(4) receptor antagonist: comparison to cisapride and RS23597-190.

Although many 5-HT (serotonin, 5-hydroxytryptamine)(4) receptor antagonists have been described, none possess the requisite oral activity and duration of action for a clinically effective therapeutic agent. The present report identifies LY353433 (1-(1-methylethyl)-N-[2-[4-[tricyclo[3.3.1.1(3,7)]dec-1-ylcarbo nyl) amino]-1-piperidinyl]ethyl]-1H-indazole-3-carboxamide), an indazole amide, as a high affinity antagonist at the 5-HT(4) receptor in the rat esophagus. LY353433 (10(-8), 3 x 10(-8), 10(-7) M) inhibited 5-HT-induced relaxation of carbamylcholine-contracted esophagus with greater potency than cisapride or RS23597-190, a known 5-HT(4) receptor ligand. Furthermore, RS23597-190 possessed marked agonist activity as did cisapride, whereas LY353433 did not relax the rat esophagus in concentrations up to 10(-5) M. LY353433 (up to 10(-5) M) did not possess appreciable affinity for adrenergic, dopaminergic, histaminergic, muscarinic or GABAergic receptors and, thus, was a highly selective 5-HT(4) receptor antagonist. In addition, LY353433 only slowly associated with an dissociated from the 5-HT(4) receptor, an attribute that conferred long-lasting 5-HT(4) receptor antagonist activity, in contrast to RS23597-190, which rapidly dissociated from the 5-HT(4) receptor. LY353433 dose-dependently inhibited the 5-HT(4) receptor-mediated ex vivo relaxation in the rat esophagus after either i.v. (0.1, 0.3 and 1.0 mg/kg) or p.o. (0.1, 0.3, 1.0 and 3.0 mg/kg) administration. Furthermore, the p.o. to i.v. dose ratio was approximately one, suggesting that LY353433 was well absorbed with excellent pharmacodynamics in the rat. LY353433 (0.3 mg/kg p.o.) blocked esophageal 5-HT(4) receptors ex vivo through 6 hr after p.o. dosing with responses returning to control by 16 hr, indicative of long duration receptor blockade. Lastly, in rats LY353433 was exceptionally safe because acute doses up to 300 mg/kg p.o. did not result in either symptoms or deaths. Thus, LY353433 is a potent, selective, orally effective, long-acting and safe 5-HT(4) receptor antagonist that is highly suitable for clinical use.

Adamantane↗
PubMed1977

Phototoxicity occurring during the manufacture of ultraviolet-cured ink.

Four workers employed in the manufacture of ultraviolet-cured inks complained of photosensitivity characterized by an intense burning sensation during sun exposure. Three of these workers developed dermatitis on exposed areas following sun exposure. Six compounds used as photoinitiators in the ink formulations were found to absorb solar ultraviolet radiation. Two preparations of mixed isomers (ortho and para) of amyl dimethylaminobenzoate were found to be phototoxic to Ehrlich ascites cells in vitro and to produce diphasic phototoxic reactions in vivo after topical application on symptomatic workers, asymptomatic workers, or previously unexposed subjects. These responses could be prevented in two subjects by the application of a 10% sulizobenzone sunscreen prior to sun exposure. Two other photoinitiators, Michler's ketone and thioxanthone were phototoxic in vitro but not after topical application in vivo.

Adult↗
PubMed1995

[BT-PABA test].

Explore the source record for details and available documents.

4-Aminobenzoic Acid↗
PubMed1996

Identification of putative 5-hydroxytryptamine(4) (5-HT4) receptors in guinea pig stomach: The effect of TKS159, a novel agonist, on gastric motility and acetylcholine release.

We investigated the existence and the function of 5-hydroxytryptamine(4) (5-HT4) receptors and the effect of TKS159, a novel agonist of 5-HT4 receptor, on guinea pig stomach. The mechanical activity and the release of [3H]ACh were measured using preparations of muscle layers attached to intramural plexus from guinea pig stomach. 5-HT in the presence of 1 microM methysergide, 1 microM ketanserin and 1 microM granisetron, 5-methoxytryptamine or TKS159 enhanced the electrical transmural stimulation-evoked contraction and [3H]ACh release in strips of the stomach in a concentration-dependent manner. This enhancement by 5-HT, 5-methoxytryptamine or TKS159 was antagonized by SDZ 205-557 or atropine. Cisapride, metoclopramide and TKS159 enhanced the electrical transmural stimulation-evoked contraction and release of [3H]ACh in a concentration-dependent manner. We conclude that the pharmacological characteristics of the receptor, which mediates contraction of the guinea pig stomach by the activation of cholinergic nerves, are consistent with its being of the putative 5-HT4 receptor type and that TKS159 is an agonist at 5-HT4 receptors.

4-Aminobenzoic Acid↗
PubMed1995

[Comparison of three indirect pancreatic function tests in severe chronic pancreatitis--personal observations].

The aim of the presented study was a comparative evaluation of the three indirect pancreatic function tests: pancreolauryl-test (PLT), NBT-PABA test and faecal chymotrypsin (CH) efficacy in detecting pancreatic exocrine function impairment in advanced chronic pancreatitis (acp). 30 patients with severe chronic pancreatitis (marked structure changes in ultrasound and CT following Cambridge criteria) confirmed by abnormal secretin-cerulein test (SCT) and 10 healthy controls underwent PLT, NBT-PABA and CH tests. The degree of pancreatic function impairment in SCT was classified following Malfertheiner into 3 subgroups: 1-mild, 2-moderate and 3-severe. All the indirect pancreatic function test were performed using commercially available kits (Temmler-Werke for PLT, Hoffman-La Roche for NBT-PABA and Boehringer Mannheim for CH) according to manufacturer instructions. PLT revealed changes in 27 (0.9), NBT-PABA-in 25 (0.83) and CH-in 22 (0.73) patients with acp. On the other hand those test have shown normal pancreatic function: PLT-in 0.9, NBT-PABA-in 0.7 and CH-in 0.8 in control group. The sensitivity of those test was increased up to 0.94 (PLT and NBT-PABA) and up to 0.88 (CH) and in the subgroup of severely impaired pancreatic function test in SCT. The concomittant use of two indirect pancreatic function tests caused increase of sensitivity up to 0.93. Our results suggest that with PLT, NBT-PABA and CH impaired pancreatic function may be succesfully recognized in advanced chronic pancreatitis, in particular, when two of them are applied concomittantly.

4-Aminobenzoic Acid↗
PubMed1997

Combined blockade of 5-HT3- and 5-HT4-serotonin receptors inhibits colonic functions in conscious rats and mice.

We have already reported that 5-hydroxytryptamine3 (5-HT3) receptor antagonists failed to modify 5-HT-accelerated colonic transit in conscious rats, but the 5-HT3 and 5-HT4 receptor dual antagonist FK1052 prevented the enhancement. In this study, the inhibitory effect on the stimulated colonic transit was not also observed with 5-HT4 receptor antagonists (SDZ205-557 and SB204070) in freely moving rats with chronic cannulas implanted into the proximal colon. In contrast, combined antagonism by simultaneous administration of ondansetron and the 5-HT4 receptor antagonist exerted a drastic inhibitory effect on the propulsive motility. Furthermore, we examined the effect of 5-HT receptor antagonists on 5-HT-induced fluid secretion in mice. Although none of these selective 5-HT receptor antagonists (YM060 and ondansetron as 5-HT3 receptor antagonist, SB204070 as 5-HT4 receptor antagonist) by itself produced a great inhibition of the 5-HT-induced diarrhea, the combination of a 5-HT3 receptor antagonist and a 5-HT4 receptor antagonist markedly reduced the diarrhea. These data suggest that 5-HT-accelerated colonic motility and 5-HT-evoked fluid secretion are mediated by both 5-HT3 and 5-HT4 receptors and that the pathways activated by these receptors may collaborate.

4-Aminobenzoic Acid↗