The negative effects of bile acids and tumor necrosis factor-alpha on the transcription of cholesterol 7alpha-hydroxylase gene (CYP7A1) converge to hepatic nuclear factor-4: a novel mechanism of feedback regulation of bile acid synthesis mediated by nuclear receptors.

Bile acids regulate the cholesterol 7alpha-hydroxylase gene (CYP7A1), which encodes the rate-limiting enzyme in the classical pathway of bile acid synthesis. Here we report a novel mechanism whereby bile acid feedback regulates CYP7A1 transcription through the nuclear receptor hepatocyte nuclear factor-4 (HNF-4), which binds to the bile acid response element (BARE) at nt -149/-118 relative to the transcription start site. Using transient transfection assays of HepG2 cells with Gal4-HNF-4 fusion proteins, we show that chenodeoxycholic acid (CDCA) dampened the transactivation potential of HNF-4. Overexpression of a constitutive active form of MEKK1, an upstream mitogen-activated protein kinase (MAPK) module triggered by stress signals, strongly repressed the promoter activity of CYP7A1 via the consensus sequence for HNF-4 embedded in the BARE. Similarly, MEKK1 inhibited the activity of HNF-4 in the Gal4-based assay. The involvement of the MEKK1-dependent pathway in the bile acid-mediated repression of CYP7A1 was confirmed by co-transfecting a dominant negative form of the stress-activated protein kinase kinase, SEK, which abolished the effect of CDCA upon CYP7A1 transcription. Treatment of transfected HepG2 cells with tumor necrosis factor alpha (TNF-alpha), an activator of the MEKK1 pathway, led to the repression of CYP7A1 via the HNF-4 site in the BARE. TNF-alpha also inhibited the transactivation potential of HNF-4. Collectively, our results demonstrate for the first time that HNF-4, in combination with a MAPK signaling pathway, acts as a bile acid sensor in the liver. Furthermore, the effects of CDCA and TNF-alpha converge to HNF-4, which binds to the BARE of CYP7A1, suggesting a link between the cascades elicited by bile acids and pro-inflammatory stimuli in the liver.

Low nitric oxide values associated with low levels of zinc and high levels of cardiac necrosis markers detected in the plasma of rabbits treated with L-NAME.

Nitric oxide plays a key role as a vasodilating agent and its deficiency is associated with ischemic heart diseases. The aim of this study was to induce biochemical alterations associated with ischemic heart lesions by blocking nitric oxide synthase. L-NAME, a nitric oxide synthase inhibitor, was administered to rabbits and its effects on blood pressure, plasma levels of nitric oxide, zinc and cardiac necrosis markers, heart histology, and electrocardiographic profile were examined. L-NAME administration reduced the nitric oxide levels and consequently increased the diastolic blood pressure. It also caused small areas of myocardial coagulative necrosis, whose dispersed nature made it undetectable by electrocardiograph, and decreased the plasma levels of zinc, which is involved in the enzymatic activities that remove the peroxides damaging the myocardium. This model is proposed for the development of drugs affecting nitric oxide levels with the aim of controlling coronary ischemia.

Identification and characterization of cis-acting elements conferring insulin responsiveness on hamster cholesterol 7alpha-hydroxylase gene promoter.

Bile acid biosynthesis occurs primarily through a pathway initiated by the 7alpha-hydroxylation of cholesterol, catalysed by cholesterol 7alpha-hydroxylase (encoded by CYP7A1). Insulin down-regulates CYP7A1 transcription. The aim of our study was to characterize the sequences of hamster CYP7A1 promoter, mediating the response to insulin. We therefore performed transient transfection assays with CYP7A1 promoter/luciferase chimaeras mutated at putative response elements and studied protein-DNA interactions by means of gel electrophoresis mobility-shift assay. Here we show that two sequences confer insulin responsiveness on hamster CYP7A1 promoter: a canonical insulin response sequence TGTTTTG overlapping a binding site for hepatocyte nuclear factor 3 (HNF-3) (at nt -235 to -224) and a binding site for HNF-4 at nt -203 to -191. In particular we show that the hamster CYP7A1 insulin response sequence is part of a complex unit involved in specific interactions with multiple transcription factors such as members of the HNF-3 family; this region does not bind very strongly to HNF-3 and as a consequence partly contributes to the transactivation of the gene. Another sequence located at nt -138 to -128 binds to HNF-3 and is involved in the tissue-specific regulation of hamster CYP7A1. The sequence at nt -203 to -191 is not only essential for insulin effect but also has a major role in the liver-specific expression of CYP7A1; it is the target of HNF-4. Therefore the binding sites for liver-enriched factors, present in the hamster CYP7A1 proximal promoter in close vicinity and conserved between species, constitute a regulatory unit important for basal hepatic expression and tissue restriction of the action of hormones such as insulin.

[Prospective study on admissions for iatrogenic adverse effects in the emergency service of hospital university center in Poitiers]. / Enquête prospective sur les admissions pour iatrogénie médicamenteuse dans le service d'accueil des urgences du centre hospitalier universitaire de Poitiers.

Hospital admissions resulting from an adverse drug reaction have been studied in the emergency unit of the university hospital in Poitiers during a 27-day period. This prospective study consisted in documenting all observations considered as an ADR by the medical practitioner in charge of the patient. There were 1235 hospital admissions to the emergency unit during the study period. Thirty-one (2.5 per cent) of admissions were considered to be drug-related. Women were more often affected than men. Patients with ADR were classified taking into account the type of pathology and the drug responsible for the effect. Dermatological and gastrointestinal reactions were predominant. Antibiotic and analgesic drugs were the most common drug groups implicated in causing an ADR.

Effects of tizanidine administration on precipitated opioid withdrawal signs in rats.

An opioid withdrawal syndrome was precipitated by naloxone administration in rats treated with morphine. The withdrawal caused alteration of several physiological signs. The aim of the study was to investigate whether the altered physiological profiles were modified by utilising tizanidine, an alpha 2 adrenergic receptor agonist which is capable of affecting faecal and urinary excretion, rectal temperature, pain threshold levels and salivation. To induce an opioid withdrawal syndrome, morphine was administered in three daily intraperitoneal injections for four days at doses of 9, 16 and 25 mg/kg (1st day), 25, 25 and 50 mg/kg (2nd day), 50, 50 and 50 mg/kg (3rd day) and 50, 50 and 100 mg/kg (4th day): naloxone was injected (30 mg/kg) i.p. 180 min after the last morphine injection. Tizanidine was administered orally at 0.17, 0.35 and 0.7 mg/kg, 60 min after the last morphine injection. Signs such as faecal and urine excretion, rectal temperature and latency times to thermal stimulus, salivation, jumping and wet dog shakes were affected in different ways by morphine, naloxone, tizanidine and by the combination of these agents. Notably, the administration of tizanidine in rats receiving morphine and naloxone decreased the intensity of certain withdrawal symptoms, including altered excretion of faeces and urine, salivation and wet dog shake behavior. Body temperature levels and nociceptive threshold values were also modified. The effects caused by tizanidine administration may be due to its alpha 2 receptor agonist activity interfering with a mechanism involved in the regulation of these previously mentioned withdrawal symptoms. Thus, the use of this drug may be indicated as a possible control of the acute phase of opioid withdrawal in heroin addicts.

Effects exerted by otilonium bromide administration on precipitated opioid withdrawal syndrome in rats.

An opioid withdrawal syndrome was induced in rats by repeated morphine administration and final naloxone injection. The withdrawal causes alteration of several physiological signs. The aim of the study was to prevent the altered physiological profiles by utilising otilonium bromide. Morphine was administered in three daily i.p. injections for 4 days at doses of 9, 16 and 25 mg/kg (1st day), 25, 25 and 50 mg/kg (2nd day), 50, 50 and 50 mg/kg (3rd day) and 50, 50 and 100 mg/kg (4th day). Naloxone was injected (30 mg/kg) i.p. 180 min after the last morphine injection. Otilonium bromide was administered orally at 0, 2, 4 and 8 mg/kg, 120 min before the naloxone administration. Signs like faecal and urine excretion, rectal temperature and pain threshold levels, salivation, jumping and wet dog shakes were affected in different ways. Notably the administration of otilonium bromide in rats receiving morphine together with naloxone decreased the intensity of certain withdrawal symptoms, such as excretion of faeces, wet dog shake behaviour, and elevated the nociceptive threshold values. The effects exhibited by otilonium bromide administration may be explained through its calcium antagonist activity interfering with a mechanism involved in the regulation of these previously mentioned withdrawal symptoms. The use of this drug is thus suggested as a possible control of some acute opioid withdrawal signs in heroin addicts.

Effects of carbamazepine treatment on pain threshold values and brain serotonin levels in rats.

The administration of carbamazepine to rats caused a significant increase in pain threshold values. Furthermore, treatment with carbamazepine lowered the concentration of tryptophan bound to plasma proteins and elevated the brain serotonin values. The high brain serotonin levels, observed in carbamazepine-treated rats, are probably attributable to an increased availability of brain tryptophan, since this amino acid has been substantially removed from the plasma protein compartment by carbamazepine treatment, which exhibits a high binding capacity to plasma proteins. The analgesic effects caused by carbamazepine administration have been attributed to increased levels of brain serotonin which is involved in the control of pain transmission.

Quantitative opioid withdrawal signs in rats: effects exerted by clothiapine administration.

An opioid withdrawal syndrome, which causes alteration of several physiological signs, was induced in rats by repeated morphine administration and final naloxone injection. The aim of this study was prevention of the altered physiological profiles by utilising clothiapine, which is capable of affecting fecal and urinary excretion, rectal temperature, pain threshold levels and salivatory behaviour. Morphine was administered in three daily intraperitoneal (ip) injections for 4 days at doses of 9, 16 and 25 mg/kg (d 1), 25, 25 and 50 mg/kg (d 2), 50, 50 and 50 mg/kg (d 3) and 50, 50 and 100 mg/kg (d 4). Naloxone was injected (30 mg/kg) ip 180 min after the last morphine injection. Clothiapine was administered orally 0.7, 2 and 6 mg/kg 2 hours before the naloxone administration. Signs such as fecal and urine excretion, rectal temperature and latency times to thermal stimulus salivation, jumping and wet dog shakes were affected in different ways by morphine, naloxone, clothiapine and combination of them. Notably the administration of clothiapine in rats receiving morphine and naloxone decreased the intensity of certain withdrawal symptoms, such as altered excretion of feces, temperature values, salivation, jumping and wet dog shakes behaviour, and elevated the nociceptive threshold values. The effects exhibited by clothiapine administration may be explained through its antimuscarinic, antiadrenergic and antidopaminergic activities interfering with the mechanisms involved in the regulation of these previously mentioned withdrawal symptoms. The use of this drug is thus suggested as a possible control of the acute phase of opioid withdrawal in heroin addicts.

Effects of administration of phentonium bromide on opioid withdrawal syndrome in rats.

This study has tested whether phentonium bromide, a quaternary ammonium anti-muscarinic agent, could reverse the signs of precipitated opioid withdrawal. Rats were treated with either saline or morphine for 4 days, after which half the rats received naloxone and half saline. Each animal also received one of four doses of phentonium bromide (0, 1, 3 and 9 mg kg(-1), i.p.). Administration of phentonium bromide in rats receiving naloxone after chronic morphine treatment reduced the intensity of withdrawal signs such as increased defecation or micturition, salivation and wet-dog shakes, and elevated the nociceptive threshold values. The effects of administration of phentonium bromide might result from its anti-muscarinic activity interfering peripherally with the mechanisms involved in the regulation of the withdrawal symptoms. The use of this drug is thus suggested as a possible means of controlling some of the signs observed during the acute phase of opioid withdrawal in heroin addicts.

Quantitative evaluation of opioid withdrawal signs in rats repeatedly treated with morphine and injected with naloxone, in the absence or presence of the antiabstinence agent clonidine.

An opioid withdrawal syndrome was induced in rats by repeated morphine administration and final naloxone injection. The withdrawal causes alteration of several physiological signs. The aim of the study was to describe a quantitative opioid abstinence syndrome to validate the methodology by utilizing clonidine, a well-known antiwithdrawal agent, and propose the procedure for the screening of antiabstinence drugs. In particular, rats were treated with saline, morphine, naloxone, morphine and naloxone and four doses of clonidine (0, 0.04, 0.1, and 0.25 mg/kg orally). In rats repeatedly exposed to morphine and then injected with naloxone, signs like excretion of feces and urine, salivation, behavioral jumping and wet dog shakes, rectal temperature, and pain threshold have been observed. Consequently, the objective symptoms observed in morphine plus naloxone-treated animals have been taken as markers of opioid withdrawal. These factors have been quantitatively measured and grouped to form a standardized procedure of opioid abstinence syndrome. In addition, it is possible to observe that the antiabstinence drug clonidine exerted effects on modified physiological signs appearing in morphine-dependent rats treated with naloxone, like fecal excretion, levels of rectal temperature, latency times, salivation as well as jumping behavior. The effects exerted by clonidine in this procedure and in other methods are compared and appear to be similar. In addition, comparative observations referring to both the previous methods and the present procedure related to the type of signs studied, the modality of evaluation, and suppressive activity exerted by the antiwithdrawal agent, clonidine, are performed: the greater accuracy of the proposed method becomes apparent. Thus, this experimental model, validated by the antiabstinence agent clonidine, is proposed as a useful screen for drugs affecting opioid withdrawal syndrome.

Effects of ondansetron administration on opioid withdrawal syndrome observed in rats.

This study tested whether a 5-HT3 receptor antagonist could reverse the signs of precipitated opioid withdrawal. Rats were treated with either saline or morphine for 4 days. After the four days, half of the rats in each group received naloxone and half received saline. Each animal also received one of four doses of ondansetron (0, 1, 2 and 4 mg/kg i.p.). Administration of ondansetron to rats receiving naloxone after chronic morphine decreased the intensity of withdrawal signs such as increased defecation, jumping and wet-dog shakes, elevated the nociceptive threshold values which were decreased by precipitated withdrawal, but produced no change in urination, rectal temperature or salivation. The effects exhibited by ondansetron administration may be explained through interference of its 5-HT3 receptor antagonist activity with serotoninergic mechanisms involved in the regulation of these withdrawal symptoms. The use of this drug is thus suggested as a possible treatment of opioid withdrawal signs in heroin addicts.

Effects of 2-guanidine-4-methylquinazoline on gastric acid secretion in rats.

In this study 2-guanidine-4-methylquinazoline (2-GMQ) appeared to decrease basal and stimulated gastric acid secretion, while structurally related compounds as dimethyl-biguanide, cyanoguanidine and 2-cyanoamino-4-methylpyrymidine did not. Thus, there is an antisecretory effect when the biguanide group is associated with a lipophilic structure. The antisecretive effects exerted by 2-GMQ are associated with anti H2-histamine activity. The anti H2-histamine nature of the effects of 2-GMQ was confirmed by the capacity of this compound of depressing the chronotropic activity of the isolated guinea pig auricle increased by histamine, as well as relaxant activity in rat uterus contracted by histamine, since both preparations are rich in H2-histamine receptors.

Regulation of the hamster cholesterol 7 alpha-hydroxylase gene (CYP7A): prevalence of negative over positive transcriptional control.

Cholesterol 7 alpha-hydroxylase plays a crucial role in cholesterol homeostasis. We investigated the regulation of this enzyme in the hamster, a suitable animal model for studying cholesterol metabolism. DNase I hypersensitivity assay revealed the presence of a hypersensitive region in the proximal promoter. Both negative (bile acids, phorbol esters and insulin) and positive (glucocorticoid hormones) effects were mediated through sequences in the region 318 bp upstream of the ATG codon. All-trans-retinoic acid, cAMP, and LDL did not affect transcriptional activity. These findings show that the hamster cholesterol 7 alpha-hydroxylase gene undergoes a predominant negative regulation, as opposed to the rat CYP7A homologous gene.

Energetic consequences of mild Giardia intestinalis infestation in Mexican children.

This study explored the effects of mild infestation with Giardia on energy intake and expenditure at rest and in activity in an urban Mexican population. Ten boys aged 6-10 y living in low-income sectors in northwest Mexico who had Giardia infestation were recruited. Energy intake, basal metabolic rate (BMR), and total free-living expenditure (TEE) measured by the doubly labeled water method were determined for 7 d during both infestation and after treatment. There was no significant difference in recorded energy intake between the two periods (7.76 and 7.70 MJ/d; P = 0.847). BMR showed no significant change in response to treatment; values were 4.79 and 4.86 MJ/d (P = 0.03). The mean TEE increased by almost 1 MJ/d in the Giardia-free period. This increase was observed in 8 of the 10 subjects; however, the overall change was not statistically significant (P = 0.08).

Potentiation of the analgesic effects of tryptophan by allopurinol in rats.

The administration to rats of tryptophan (CAS 73-22-3) in high dosage causes a significant increase in pain threshold values. The analgesic effects of tryptophan are potentiated by allopurinol (CAS 315-30-0). The analgesic effects shown by tryptophan injection are associated with increased levels of serotonin and 5-hydroxyindoleacetic acid in some areas of the brain. The combined allopurinol and tryptophan treatment elevates the serotonin levels furtherly when they are compared with the values observed in animals receiving tryptophan only. The analgesia caused by tryptophan administration has been attributed to an increased activity of the serotoninergic system involved in the control of pain transmission.

2-substituted derivatives of benzimidazole inhibiting gastric acid secretion in rats.

Benzimidazole and its 2-derivatives with amino, carbamonitrile, urea, and guanidine groups have been tested for their activity on gastric secretory process. The carbamonitrile-, urea-, and guanidine compounds decrease gastric acid secretion, basal and stimulated with histamine or betazole, in Shay-rats and depress the guinea pig auricle activity stimulated by betazole. The results suggest that the studied 2-substituted benzimidazole compounds exhibit anti H2-histamine activity.

Antisecretory activity of 6-aminoindazole in rats.

Administration of 6-aminoindazole (6-AIN) and 5-aminoindazole (5-AIN) to rats depressed gastric acid secretion, both basal and carbachol-stimulated. 6-AIN proved to be more active than 5-AIN in decreasing the stimulated secretory process. The antisecretory activity of 6-AIN appears to be partially an antihistamine effect, since this compound antagonized the stimulatory action of betazole on isolated guinea pig auricle. The antisecretory activity of 6-AIN is probably associated with an antimuscarinic effect, since the molecule decreased carbachol-stimulated gastric acid secretion in rats and depressed neostigmine-stimulated motility of duodenum and colon in the anaesthetized cat. It also lessened the hypertonus of isolated guinea-pig trachea caused by pilocarpine. The antisecretory effects of 6-AIN also appear to be associated with myolytic activity, since it decreased the spontaneous motility of duodenum and colon in anaesthetized cats and the spontaneous myoactivity of isolated jejunum of the rabbit. It depressed the contractions of isolated guinea-pig ileum caused by histamine and decreased the spasmogenic effects of barium chloride on isolated guinea-pig gall bladder. These results suggest that 6-AIN probably depresses gastric acid secretion by interfering with both histamine and acetylcholine receptors and with other receptors involved in the secretory process.

Antiprostatic effect associated with zinc depletion in cimetidine-treated rats.

The administration of large doses of cimetidine for 45 days to rats decreased the weight of the prostate and lowered the prostate levels of the zinc metal ion. Since the zinc ion is essential to the prostate growth and androgen action and since cimetidine lowers prostatic zinc content, the weight loss of the prostate observed in cimetidine treated animals can be reasonably attributed to the removal of zinc caused by cimetidine administration.

Observations on the chemical structure and cytotoxic activity of marycin, a hematoporphyrin derivative.

This paper describes the preparation, chemical structure and cytotoxic activity of marycin, a hematoporphyrin derivative. Marycin has been prepared by condensing hematoporphyrin dimethyl ester in the presence of p-toluenesulfonic acid and reducing the product with lithium aluminum hydride. The product appeared to be pure by thin-layer chromatography (TLC) and high-performance liquid chormatography (HPLC). The product, analyzed by UV-visible absorbance and fluorescence spectra, appears to be related to the parent hematoporphyrin compound. The product was also analyzed by NMR and Mass spectra: a dimeric structure can be assigned to marycin: this appears to have an oxide bridge between C2-chains of two porphyrin units and hydroxyl groups instead of carboxyls. Marycin was screened for cytotoxic activity against ZR-75, MCF-7, HT-29, K-562, human tumor cell lines and the MRC-9 human embryonic cell line. Marycin decreases the growth index, measured in the radiometric assay, as 14CO2 production. The cytotoxic activity was dose-dependent and is attributable to the pure compound, marycin. Marycin is active at low doses but the activity varies with the cell line studied. The compound had low toxicity versus MRC-9 normal cell line. The compound is active without light activation. How marycin acts is a matter of speculation. Marycin is highly liposoluble and would be expected to have high toxicity for tumors.

Anti-convulsant effects by reduced glutathione and related aminoacids in rats treated with isoniazid.

Rats were treated with different doses of isoniazid (INH) causing convulsions. Lethal dose (DL50) and effective convulsant dose (ED50) were calculated. Reduced glutathione (GSH) and related aminoacids were administered to rats receiving INH: the latency and duration of convulsions were recorded; cerebral gamma-aminobutyric acid (GABA) concentrations were determined in rats receiving INH and an association of GSH and INH. GSH and its related aminoacids as cysteine and glycine greatly decreased the duration of INH-induced seizures, while glutamic acid did not protect against convulsions caused by INH. Furthermore, INH causes a decrease in cerebral GABA levels to about half and GSH repeated pretreatment did, however, not prevent the INH induced decline of GABA content: hence, the anticonvulsant effect of GSH can not be ascribed to the restoration of normal levels of anti-epilectically acting GABA, but can be attributed to cysteine and glycine, aminoacids linked to GSH.