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Assessing the emetic potential of PDE4 inhibitors in rats.

1. Type 4 phosphodiesterase (PDE4) inhibitors mimic the pharmacological actions of alpha(2)-adrenoceptor antagonists. This has been postulated as the mechanism by which PDE4 inhibitors induce emesis and was also demonstrated by their ability to reverse xylazine/ketamine-induced anaesthesia. We further characterized this latter effect since it appears to reflect the emetic potential of PDE4 inhibitors. 2. Selective inhibitors of PDE 1, 2, 3, 4 and 5 were studied in rats, on the duration of anaesthesia induced by the combination of xylazine (10 mg kg(-1), i.m.) and ketamine (10 mg kg(-1), i.m.). PMNPQ (i.e. 6-(4-pyridylmethyl)-8-(3-nitrophenyl)quinoline) - PDE4 inhibitor: 0.01 - 3 mg kg(-1)), like MK-912 (alpha(2)-adrenoceptor antagonist: 0.01 - 3 mg kg(-1)), dose-dependently reduced the duration of anaesthesia. In contrast, vinpocetine (PDE1 inhibitor), EHNA (PDE2 inhibitor), milrinone (PDE3 inhibitor) and zaprinast (PDE5 inhibitor) had no significant effect at the doses tested (1 - 10 mg kg(-1)). Analysis of plasma and cerebrospinal fluid (CSF) of treated animals confirmed the absorption and distribution to the brain of the inactive inhibitors. 3. Neither MK-912 (3 mg kg(-1)) nor PMNPQ (0.1 - 1 mg kg(-1)) altered the duration of anaesthesia induced via a non-alpha(2)-adrenoceptor pathway (sodium pentobarbitone 50 mg kg(-1), i.p.). 4. Central NK(1) receptors are involved in PDE4 inhibitor-induced emesis. Consistently, [sar(9), Met(O(2))(11)]-substance P (NK(1) receptor agonist, 6 microg i.c.v.) reduced the duration of anaesthesia induced by xylazine/ketamine. 5. In summary, this model is functionally coupled to PDE4, specific to alpha(2)-adrenoceptors and relevant to PDE4 inhibitor-induced emesis. It therefore provides a novel way of evaluating the emetic potential of PDE4 inhibitors in rats.

3',5'-Cyclic-AMP Phosphodiesterases↗

Quantitative analysis of anti-emetic principle in the tubers of Pinellia ternata by enzyme immunoassay.

A crude globulin fraction was isolated from the tubers of Pinellia ternata (Thunb.) Breit. Tubers of P. ternata are one of the well known Chinese traditional medicines. It is used on account of its anti-emetic effect. 6KDP was separated by means of gel filtration and chromatography on CM-Toyopearl 650 M from the crude globulin fraction. 6KDP is a glycoprotein of M.W. 6 kDa. 6KDP has an anti-emetic activity and hemagglutination activity. Both activities dropped during heat treatment. For the purpose to evaluate the quality of the powdered tubers of P. ternata, the quantitative analysis by means of EIA was established. The contents of 6KDP varied from 5.75 to 8.30%. The assay demonstrated a low cross-reaction with the crude globulin fraction of Colocasia antiquorum, a member of the same family as P. ternata. 6KDP is one of major proteins in the tubers of P. ternata. Thus 6KDP is a marker for quantitative analysis of the tubers of P. ternata.

Antiemetics↗

Improving the quality of anti-emetic therapy.

The outcome of anti-emetic therapy (AT) to women with gynaecological cancer receiving chemotherapy, in total 552 courses, was registered for a 1-year period. A quality improvement (QI) programme was established, based on three standardized AT regimens. Evaluation and documentation of AT effects were performed by the patients themselves, reporting the number of emetic episodes and degree of nausea for 5 days following the chemotherapeutic treatment. The results were visualized in monthly graphic displays. Various factors which might contribute to the achieved improvements are discussed. In conclusion, the continuous QI process seems to be a suitable method in guiding direct patient care.

Antiemetics↗

The costs of health care: implications for anti-emetic therapy.

Health economists assess new drug innovations to improve choice. Decision-making techniques for cost analysis should include not only direct costs but costs in terms of increased health benefit, reduced mortality and improved quality of life. The use of anti-emetic drugs results in a significant improvement in the quality of life of patients and decision making on the use of anti-emetic drugs should fully evaluate this patient benefit.

Ambulatory Care↗

The rice culture filtrate of Bacillus cereus isolated from emetic-type food poisoning causes mitochondrial swelling in a HEp-2 cell.

Rice culture filtrates of Bacillus cereus SA-50, an emetic-type strain, produced a toxin which caused cytoplasmic vacuole formation in HEp-2 and HeLa cells. Electron microscopic observation revealed that the apparent vacuoles in HEp-2 seen under a light microscope were actually swollen mitochondria. The oxygen consumption of HEp-2 cells was accelerated by the addition of the rice culture filtrate as was measured with a polarographic oxymeter; a respiratory control ratio was 1.0 for control cells, while 1.4 for ones with the filtrates. The culture filtrates showed a similar effect on the isolated mouse liver mitochondria; respiratory control ratios for the mitochondria with and without the filtrates were 3.6 and 1.0, respectively. The affecting manner of the culture filtrates on the oxygen consumption of mitochondria was similar to that of 2,4-dinitrophenol, suggesting that the culture filtrate contains a toxin acting as an uncoupler of oxidative phosphorylation in mitochondria. It is likely that the culture filtrates containing the emetic toxin of B. cereus causes mitochondrial swelling with a close relationship to the uncoupling of the oxidative phosphorylation of mitochondria.

Animals↗

Growth conditions of and emetic toxin production by Bacillus cereus in a defined medium with amino acids.

The growth and emetic toxin (cereulide) production of Bacillus cereus strains in defined culture media were studied. We found that a fully synthetic medium (CADM) allowed the production of emetic toxin and the addition of glucose enhanced it. By subtracting each amino acid from CADM, we found that only three amino acids, valine, leucine and threonine, were essential for growth and toxin production by B. cereus. The addition of high levels (50 mM) of leucine, isoleucine and glutamic acid decreased the toxin production. Other amino acids had no effect at this concentration.

Amino Acids↗

Evaluation of the anti-emetic action of domperidone.

The findings of a study into the anti-emetic properties of domperidone are reported. When the drug was given prophylactically with either morphine or pethidine the study revealed that any anti-emetic property of domperidone was of short duration and that it would not be suitable as a prophylaxis against opiate-induced emesis. Domperidone is not being introduced into clinical practice in the United Kingdom on the basis of current study.

Adolescent↗

The oculo-emetic reflex. A rationalisation of postophthalmic anaesthesia vomiting.

Data related to the incidence of postoperative vomiting were collected during prospective studies on 607 ophthalmic surgical patients of all ages who underwent halothane anaesthesia with spontaneous ventilation. Analysis of data in respect of age, sex and surgical site variables, and time of onset of vomiting, identified a female sex-related vomiting incidence of about 13% and a squint-related vomiting incidence of about 41%; no relationship between age and vomiting was identified. The analyses showed that squint surgery predisposed particularly to emesis, and was associated with a high incidence of both early and delayed vomiting. It is suggested that the apparent absence of an age-vomiting relationship in ocular, and especially squint, surgery, and the high incidence of vomiting, particularly the early vomiting associated only with squint surgery, provide clinical evidence for the existence of an oculo-emetic reflex. Our observations show that intra- and postoperative surgical stimulation of this oculo-emetic reflex is reflected in the incidences of vomiting after ocular surgery.

Adolescent↗

Anti-emetic effect of high-dose metoclopramide vs alizapride--a randomised crossover study.

A randomised double-blind crossover study was undertaken to compare the anti-emetic efficacy of alizapride against high dose metoclopramide. A total of 32 patients on cisplatin were randomised to receive either high dose metoclopramide (7 mg kg-1 day-1) or alizapride (5 mg kg-1 day-1). Anti-emetic responses in terms of control of vomiting episodes were similar in both regimens (59%). However, patients showed a statistically significant preference for high dose metoclopramide (P = 0.02). Side effects of both regimens were minimal. We conclude that alizapride is not superior to high dose metoclopramide in controlling cisplatin induced vomiting.

Adult↗

A possible anti-emetic role for sodium valproate in cytotoxic chemotherapy.

We report two patients with acute leukaemia who received emetogenic cytotoxic drugs and were on therapeutic doses of sodium valproate for epilepsy. Neither patient reported significant nausea nor vomited at any time during the chemotherapy, at times requiring no anti-emetic treatment whatsoever. We suggest that this absence of nausea was due to an anti-emetic effect of sodium valproate.

Antiemetics↗

Anti-emetic prophylaxis with oral tropisetron and/or dexamethasone.

BACKGROUND: The corticosteroid dexamethasone and the serotonine3 -antagonist tropisetron are both effective drugs for the prophylaxis of post-operative nausea and vomiting (PONV) when given intravenously. The aim of this trial was to evaluate the oral use of both drugs as part of a routine oral premedication and to compare their single and combined effectiveness. MATERIALS AND METHODS: In this randomized, placebo-controlled, double-blind study, 320 inpatients with a moderate-high risk of PONV (> or = 40% according to two validated risk scores) received an oral premedication 1-2 h pre-operatively with placebo, a fixed dose of tropisetron 5 mg, dexamethasone 8 mg, or a combination of both drugs. A standardized general anaesthesia was performed, including benzodiazepine premedication, propofol, rocuronium, desflurane in air/O2, fentanyl or sufentanil followed by a continuous infusion of remifentanil. Post-operative analgesia and anti-emetic rescue medication were standardized. The main outcome measures were the severity of PONV within the first 24 h (rated by a standardized scoring algorithm). The incidence of PONV was used as the secondary outcome. RESULTS: Data from 310 patients were analyzed. The mean severity score in the placebo-, tropisetron-, dexamethasone- and the combined-groups was 1.37, 0.8, 0.8 and 0.38, respectively. The incidence of PONV of any severity was 59.2%, 37.5%, 40% and 22.8%, respectively. The reduction of the incidence and the severity of PONV were statistically significant with all three interventions. Results from additional analyses suggested that both drugs were equally effective and that there was a simple additive effect of tropisetron and dexamethasone compared with placebo. CONCLUSION: Oral tropisetron and dexamethasone were both equally effective in reducing the severity and incidence of post-operative nausea and vomiting. The latter could be reduced by approximately 35% in a population of moderate-high risk for PONV. Both drugs had an additive effect. However, even in the combination group there still remained an unacceptably high incidence of PONV of more than 20%. This highlighted the need for a multimodal anti-emetic approach in high-risk patients and the importance of treatment of PONV.

Administration, Oral↗

Update on anti-emetics for chemotherapy-induced emesis.

The need to control chemotherapy-induced emesis has stimulated research into anti-emetics. Emesis is not only unpleasant, but negatively impacts on global quality of life. The development of two new classes of drugs has been responsible for the major advances in anti-emesis. The 5 hydroxytryptamine3 (5HT3) antagonists in combination with dexamethasone significantly improved the control of acute post chemotherapy emesis, but delayed emesis which can last for several days was still problematic, yet its incidence was underestimated by clinicians. Both the control of acute and delayed emesis was improved when the neurokinin1 (NK1) receptor antagonists were added to 5HT3 antagonists and steroids. The complete control of delayed emesis was improved by 21% with little toxicity. The triple drug combination has become the standard of care for preventing the emesis associated with cytotoxic drugs of high emetic potential.

Administration, Oral↗

ANTI-EMETIC ACTIVITY OF PHENOTHIAZINES IN RELATION TO THEIR CHEMICAL STRUCTURE.

Twelve phenothiazine derivatives have been studied for anti-emetic potency in dogs against emesis induced by apomorphine. The PD(50)s of all the compounds were determined and the activities compared with chlorpromazine hydrochloride as standard. Thioproperazine methanesulphonate was 300 times more active than chlorpromazine hydrochloride and twice as active as perphenazine sodium citrate. The anti-emetic activity of the compounds has been correlated with their chemical structure.

Animals↗

The anti-emetic effects of CP-99,994 in the ferret and the dog: role of the NK1 receptor.

1. The selective NK1 receptor antagonist, CP-99,994, produced dose-related (0.1-1.0 mg kg-1, s.c.) inhibition of vomiting and retching in ferrets challenged with central (loperamide and apomorphine), peripheral (CuSO4) and mixed central and peripheral (ipecac, cisplatin) emetic stimuli. 2. Parallel studies with the enantiomer, CP-100,263 (1 mg kg-1, s.c.), which is > 1,000 fold less potent as a NK1 antagonist, indicated that it was without significant effect against CuSO4, loperamide, cisplatin and apomorphine-induced emesis. Against ipecac, it inhibited both retching and vomiting, expressing approximately 1/10th the potency of CP-99,994. 3. The 5-HT3 receptor antagonist, tropisetron (1 mg kg-1, s.c.) inhibited retching and vomiting to cisplatin and ipecac, but not CuSO4 or loperamide. 4. CP-99,994 (1 mg kg-1, i.v.) blocked retching induced by electrical stimulation of the ventral abdominal vagus without affecting the cardiovascular response, the apnoeic response to central vagal stimulation or the guarding and hypertensive response to stimulation of the greater splanchnic nerves. CP-99,994 (1 mg kg-1, i.v.) did not alter baseline cardiovascular and respiratory parameters and it failed to block the characteristic heart rate, blood pressure and respiratory rate/depth changes in response to i.v. 2-methyl-5-HT challenge (von Bezold-Jarisch reflex). 5. Using in vitro autoradiography, [3H]-substance P was shown to bind to several regions of the ferret brainstem with the density of binding in the nucleus tractus solitarius being much greater than in the area postrema. This binding was displaced by CP-99,994 in a concentration-related manner. 6. In dogs, CP-99,994 (40 micrograms kg-1 bolus and 300 micrograms kg-1 h-1, i.v.) produced statistically significant reductions in vomiting to CuSO4 and apomorphine as well as retching to CuSO4. 7. Together, these studies support the hypothesis that the NK1 receptor antagonist properties of CP-99,994 are responsible for its broad spectrum anti-emetic effects. They also suggest that CP-99,994 acts within the brainstem, most probably within the nucleus tractus solitarius although the involvement of the area postrema could not be excluded.

Animals↗

Prolonged anti-emetic activity and 5-HT3-receptor antagonism by BRL 46470 in conscious ferrets.

The anti-emetic activity of oral and intravenously-administered BRL 46470 (endo-N-(8-methyl-8-azabicyclo[3.2.1]oct-3yl)-2,3-dihydro-3,3- dimethyl-indole-1-carboxamide HCl) has been assessed in conscious ferrets. BRL 46470 (0.05-0.5 mg kg-1, p.o.) dose-dependently prevented emesis evoked over a 2 h period by total body X-irradiation. This anti-emetic activity occurred with oral or intravenously-administered BRL 46470 even when dosed 3-4 h before radiation. In conjunction with data obtained in other species, we conclude that BRL 46470 has a potent and long-lasting ability to antagonize actions that are mediated by the 5-HT3 receptor in-vivo.

Administration, Oral↗

Quantitative analysis of cereulide, the emetic toxin of Bacillus cereus, produced under various conditions.

This paper describes a quantitative and sensitive chemical assay for cereulide, the heat-stable emetic toxin produced by Bacillus cereus. The methods previously available for measuring cereulide are bioassays that give a toxicity titer, but not an accurate concentration. The dose of cereulide causing illness in humans is therefore not known, and thus safety limits for cereulide cannot be indicated. We developed a quantitative and sensitive chemical assay for cereulide based on high-performance liquid chromatography (HPLC) connected to ion trap mass spectrometry. This chemical assay and a bioassay based on boar sperm motility inhibition were calibrated with purified cereulide and with valinomycin, a structurally similar cyclic depsipeptide. The boar spermatozoan motility assay and chemical assay gave uniform results over a wide range of cereulide concentrations, ranging from 0.02 to 230 microg ml(-1). The detection limit for cereulide and valinomycin by HPLC-mass spectrometry was 10 pg per injection. The combined chemical and biological assays were used to define conditions and concentrations of cereulide formation by B. cereus strains F4810/72, NC7401, and F5881. Cereulide production commenced at the end of logarithmic growth, but was independent of sporulation. Production of cereulide was enhanced by incubation with shaking compared to static conditions. The three emetic B. cereus strains accumulated 80 to 166 microg of cereulide g(-1) (wet weight) when grown on solid medium. Strain NC7401 accumulated up to 25 microg of cereulide ml(-1) in liquid medium at room temperature (21 +/- 1 degrees C) in 1 to 3 days, during the stationary growth phase when cell density was 2 x 10(8) to 6 x 10(8) CFU ml(-1). Cereulide production at temperatures at and below 8 degrees C or at 40 degrees C was minimal.

Bacillus cereus↗

Identification and partial characterization of the nonribosomal peptide synthetase gene responsible for cereulide production in emetic Bacillus cereus.

Cereulide, a depsipeptide structurally related to valinomycin, is responsible for the emetic type of gastrointestinal disease caused by Bacillus cereus. Due to its chemical structure, (D-O-Leu-D-Ala-L-O-Val-L-Val)(3), cereulide might be synthesized nonribosomally. Therefore, degenerate PCR primers targeted to conserved sequence motifs of known nonribosomal peptide synthetase (NRPS) genes were used to amplify gene fragments from a cereulide-producing B. cereus strain. Sequence analysis of one of the amplicons revealed a DNA fragment whose putative gene product showed significant homology to valine activation NRPS modules. The sequences of the flanking regions of this DNA fragment revealed a complete module that is predicted to activate valine, as well as a putative carboxyl-terminal thioesterase domain of the NRPS gene. Disruption of the peptide synthetase gene by insertion of a kanamycin cassette through homologous recombination produced cereulide-deficient mutants. The valine-activating module was highly conserved when sequences from nine emetic B. cereus strains isolated from diverse geographical locations were compared. Primers were designed based on the NRPS sequence, and the resulting PCR assay, targeting the ces gene, was tested by using a panel of 143 B. cereus group strains and 40 strains of other bacterial species showing PCR bands specific for only the cereulide-producing B. cereus strains.

Amino Acid Sequence↗

Complete sequence analysis of novel plasmids from emetic and periodontal Bacillus cereus isolates reveals a common evolutionary history among the B. cereus-group plasmids, including Bacillus anthracis pXO1.

The plasmids of the members of the Bacillus cereus sensu lato group of organisms are essential in defining the phenotypic traits associated with pathogenesis and ecology. For example, Bacillus anthracis contains two plasmids, pXO1 and pXO2, encoding toxin production and encapsulation, respectively, that define this species pathogenic potential, whereas the presence of a Bt toxin-encoding plasmid defines Bacillus thuringiensis isolates. In this study the plasmids from B. cereus isolates that produce emetic toxin or are linked to periodontal disease were sequenced and analyzed. Two periodontal isolates examined contained almost identical approximately 272-kb plasmids, named pPER272. The emetic toxin-producing isolate contained one approximately 270-kb plasmid, named pCER270, encoding the cereulide biosynthesis gene cluster. Comparative sequence analyses of these B. cereus plasmids revealed a high degree of sequence similarity to the B. anthracis pXO1 plasmid, especially in a putative replication region. These plasmids form a newly defined group of pXO1-like plasmids. However, these novel plasmids do not contain the pXO1 pathogenicity island, which in each instance is replaced by plasmid specific DNA. Plasmids pCER270 and pPER272 share regions that are not found in any other pXO1-like plasmids. Evolutionary studies suggest that these plasmids are more closely related to each other than to other identified B. cereus plasmids. Screening of a population of B. cereus group isolates revealed that pXO1-like plasmids are more often found in association with clinical isolates. This study demonstrates that the pXO1-like plasmids may define pathogenic B. cereus isolates in the same way that pXO1 and pXO2 define the B. anthracis species.

Amino Acid Sequence↗