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J Hughes

Publications and source records attributed to J Hughes.

At least 361 records · Page 20Linked to original sources
PubMed1991

Anxiolytic effects of CCK-B antagonists.

PD134308 and PD135158 are highly selective CCK-B receptor antagonists and were used to investigate the role of CCK-B receptors in aversive responding in rodent and primate models of anxiety. Both PD134308 and PD135158 were as effective as diazepam to antagonise aversive behaviour in the mouse light/dark discrimination test, in the rat social interaction and elevated X-maze tests, and in a marmoset 'human threat' model. However, the CCK-B antagonists were much more potent than diazepam and their effects were recorded over an extensive dose range. Furthermore, even at high doses, sedation or muscle relaxation was not observed and anxiogenesis was absent after withdrawal from a subchronic treatment. In contrast, withdrawal from drugs of abuse, diazepam, alcohol, cocaine and nicotine was associated with a withdrawal anxiogenesis that was completely prevented by PD134308 and PD135158. It is concluded that CCK-B receptors are involved in aversive-anxiety responding and that CCK-B receptor antagonists may provide a novel and improved approach to the treatment of anxiety and withdrawal from drugs of abuse.

Animals↗
PubMed1991

Studies on the effect of systemic PD134308 (CAM 958) in spinal reflex and pain models with special reference to interaction with morphine and intrathecal galanin.

The effect of intravenous (i.v.) PD134308, which is a CCK-B antagonist, morphine and intrathecal (i.t.) galanin (GAL) on the excitability of the spinal nociceptive flexor reflex and in the hot plate test was examined in rats. PD134308 (1 mg/kg, i.v.) caused a weak, naloxone-reversible depression of the flexor reflex and moderate antinociception in the hot plate test. PD134308 significantly potentiated the antinociceptive effect of morphone, as well as its depressive effect on the flexor reflex. PD134308 and i.t. GAL synergistically depressed the flexor reflex, which was reversed by naloxone. Finally, the magnitude and duration of the depression of the flexor reflex by morphine was synergistically increased by coadministering i.v. PD134308 and i.t. GAL. The results demonstrate that a CCK antagonist directed to the central CCK-B receptor potentiates the analgesic effects of opioid and non-opioid drugs at spinal level in the rat, thus supporting the notion that CCK in the CNS may be an endogenous, physiological opioid antagonist.

Analgesics↗
PubMed1991

Highly selective kappa opioid analgesics. 4. Synthesis of some conformationally restricted naphthalene derivatives with high receptor affinity and selectivity.

This paper describes the synthesis and kappa and mu opioid receptor binding affinity of some conformationally restrained derivatives of the arylacetamide group in the selective kappa opioid receptor agonist (+/-)-trans-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl]benzo [b]thiophene-4-acetamide monohydrochloride (1,PD117302), which is an analogue of U-50, 488. The methyl-substituted derivatives (+/-)-trans-N, alpha-dimethyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzo-[b] thiophene-4-acetamide monohydrochloride (6a,b) possess significantly weaker affinity than 1 for the kappa opioid receptor (Ki = 172 and 3.7 nM, respectively). It is proposed that this is due to the conformational restriction imposed by the methyl group of 6. In order to test this proposal the acenaphthene derivative and the 4,5-dihydro-3H-naphtho [1,8-bc]thiophene derivative were prepared. The acenaphthene derivative (+)-N-methyl-N-[7-(1-pyrrolidinyl)-1-oxaspiro [4.5]dec-8-yl]acenaphthenecarboxamide monohydrochloride (9) was found to have high kappa opioid receptor affinity and selectivity (kappa Ki = 0.37 +/- 0.05 nM, mu/kappa = 659, delta/kappa = 1562) and is 100 times more potent than morphine as an analgesic in the rat paw pressure test for analgesia after intravenous administration (MPE50 = 0.014 and 1.4 mg/kg, respectively). The 4,5-dihydro-3H-naphtho[1,8-bc]thiophene derivative (-)-4,5-dihydro-N-methyl-N-[7-(1-pyrrolidinyl)-1-oxaspiro [4.5]dec-8-yl]-3H-naphthol[1,8-bc]thiophene-5-carboxamide p-toluenesulfonate (17) also has high kappa opioid receptor affinity and selectivity (kappa Ki = 4.65 nM, mu/kappa = 109).

Analgesics↗
PubMed1991

Rationally designed "dipeptoid" analogues of CCK. alpha-Methyltryptophan derivatives as highly selective and orally active gastrin and CCK-B antagonists with potent anxiolytic properties.

This paper describes the synthesis and structure-activity relationships (SAR) leading to the first rational design of "dipeptoid" analogues of the neuropeptide cholecystokinin (CCK). Compounds [R-(R*,S*)]-4-[2-[3-(1H-indol-3-yl)-2-methyl-1-oxo-2-[(tricyclo [3.3.1.1(3,7)]dec-2-yloxy)carbonyl]amino]propyl]amino]-3- phenylpropyl]-amino]-4-oxo-2-butenoic acid, [R-(R*,R*)]-4-[2-[3-(1H-indol-3-yl)-2-methyl-1-oxo-2-[(tricyclo [3.3.1.1(3,7)]dec-2-oxy)carbonyl]amino]propyl]amino]-1- phenylethyl]amino]-4-oxo-2-butenoic acid, and [R-(R*,R*)]-4-[2-[3-(1H-indol-3-yl)-2-methyl-1-oxo-2-[(tricyclo [3.3.1.1(3,7)]dec-2-yloxy)carbonyl]amino]propyl]amino]-1- phenylethyl]amino]-4-oxobutanoic acid (29d) have CCK-B binding affinities of IC50 = 0.8, 0.7, and 1.7 nM with a CCK-A/CCK-B ratio of 550, 1100, and 2500, respectively. Compound 27 is well-absorbed and is equiactive by the subcutaneous (sc) and intravenous (iv) routes of administration in the Ghosh and Schild test in rats in inhibiting pentagastrin stimulated gastric acid secretion with ED50 = 0.07 (0.01-0.34) mumol/kg. Compound 29d is anxiolytic in mice in the black-white test box over the range 0.0001-30 mg/kg sc, comparable in activity to diazepam over the range 0.125-1 mg/kg ip), and also active in this test when dosed orally over a wide range from 0.0001 to 10 mg/kg.

Animals↗
PubMed1991

Iron fortification of infant milk formula: the effect on iron status and immune function.

We conducted a randomized double-blind trial of a cow's milk infant formula with increased iron fortification in order to confirm its safety and to measure its effects on iron status and immune function. A group of full-term, well nourished and healthy infants was followed from the age of 3 months to 1 year. A control group of 74 infants was given a commercially available infant formula containing 8.3 mg Fe/100g. The test group of 75 infants received a similar formula with 40 mg Fe/100 g. The formula with the extra iron proved to be safe and, when compared with the control group, the children in the test group had significantly improved iron status as reflected by the proportion of children classed as normal (25 of 61 cf. 44 of 65; p less than 0.003), and by the mean values of the haemoglobin concentration (11.5 cf. 11.9 g/dl; p = 0.04), red cell distribution width (15.5% cf. 14.4%; p = 0.0005), red cell zinc protoporphyrin (3.4 cf. 4.0 micrograms/g Hb; p = 0.04) and ferritin (29 cf. 17.3 micrograms/l; p = 0.004). The extra iron fortification depressed zinc concentration in plasma (90.6 cf. 83.5 micrograms/l; p = 0.05). There was no significant difference between the two groups for laboratory measures of immune function or for incidence of infection. No adverse effects such as infection could be attributed to the increased iron. We conclude that iron fortification of cow's milk infant formula may be safely increased to 40 mg/100 g (i.e. by a factor of 4.8 over the common concentration of 8.3 mg/100 g), but that this has less than the expected effect on iron status. Further studies are required to define (a) the long-term role of facilitators of iron absorption such as ascorbic acid, (b) the interaction of iron with absorption of divalent trace elements such as zinc, and (c) the effect of iron status on immune function and susceptibility to infection.

Anemia, Hypochromic↗
PubMed1991

Cholecystokinin modulates the release of dopamine from the anterior and posterior nucleus accumbens by two different mechanisms.

The effects of various cholecystokinin (CCK)-related peptides were investigated on 35 mM K(+)-stimulated endogenous dopamine release from slices of either anterior or posterior nucleus accumbens of the rat. CCK sulphated octapeptide (1-10 microM), but not pentagastrin or CCK unsulphated octapeptide, was found to cause a dose-dependent increase in the release from the posterior nucleus accumbens. This effect was blocked by low doses of the CCKA receptor antagonist L364,718 (10 nM) but not the CCKB receptor antagonist L365,260. In the anterior nucleus accumbens CCK sulphated octapeptide (1 microM) and CCK unsulphated octapeptide (0.1-1 microM) inhibited the dopamine release, and this effect was blocked by L365,260 (10-100 nM) but not by L364,718. These results suggest that CCK has a different effect on dopamine release from the anterior and posterior nucleus accumbens and that these effects are mediated by two different types of CCK receptor.

Animals↗
PubMed1991

Effect of cholecystokinin octapeptide on endogenous amino acid release from the rat ventromedial nucleus of the hypothalamus and striatum.

The sulphated octapeptide of cholecystokinin (CCK-8S) was found to cause a dose-dependent increase in the basal release of aspartate, glycine, and gamma-aminobutyric acid from the striatum and the ventromedial nucleus of the hypothalamus (VMH). No effect on amino acid release was observed after electrical (VMH) or potassium (striatum) stimulation. Experiments performed using the CCKB-selective antagonist L-365,260 and the CCKA-selective antagonist L-364,718 suggested that this action of CCK-8S was mediated via the CCKB receptor. The ability of CCK-8S to evoke amino acid release was not dependent on the presence of extracellular calcium, though the effect was abolished by tetrodotoxin. Inhibition of protein kinase activity by staurosporine prevented the excitatory effects of CCK-8S on amino acid release.

Alkaloids↗
PubMed1991

The behavioural properties of CI-988, a selective cholecystokininB receptor antagonist.

1. The behavioural effects of a selective cholecystokininB (CCKB) receptor antagonist CI-988 were investigated in rodents. 2. In three rodent tests of anxiety (rat elevated X-maze, rat social interaction test and mouse light/dark box) CI-988 over the dose range 0.001-10.0 mg kg-1, (i.p.) produced an anxiolytic-like action. The magnitude of this effect was similar to that of chlordiazepoxide (CDP). In contrast, the selective CCKA receptor antagonist, devazepide, was inactive. CI-988 also showed anxiolytic-like action in the rat conflict test but the magnitude of this effect was about 2.5 fold less than that of CDP. 3. Central but not peripheral administration of the selective CCKB receptor agonist, pentagastrin, like FG 7142, produced an anxiogenic-like action. 4. The pentagastrin-induced anxiety was dose-dependently antagonized by CI-988, whereas devazepide was inactive. However, ten times higher doses of CI-988 were required to block a similar action of FG 7142. 5. In contrast to CDP, CI-988 up to 3000 fold higher doses than those inducing anxiolysis was inactive in tests measuring sedation and ataxia. It also failed to antagonize pentylenetetrazol-induced tonic seizures. Furthermore, CI-988 did not interact with alcohol or barbiturates. Thus, CI-988 appears to be an anxioselective compound. 6. The anxiolytic-like action of CDP in the rat elevated X-maze was dose-dependently antagonized by flumazenil. In contrast, the benzodiazepine receptor antagonist failed to block a similar effect of CI-988. 7. Thus, CI-988 shows anxiolytic-like activity in several animal models of anxiety. The anxiolytic-like effect of CI-988 involves a novel mechanism of action, that is likely to be mediated by selective antagonism of the brain CCKB receptor. It is suggested that CI-988 should have a better side-effect profile in man than the benzodiazepines.

Animals↗
PubMed1991

The effect of CCKB/gastrin antagonists on stimulated gastric acid secretion in the anaesthetized rat.

1. The urethane-anaesthetized, vagotomised rat preparation was used to investigate the effects of the histamine H2-antagonist ranitidine, the proton pump inhibitor omeprazole and the CCKB/gastrin antagonists CI-988, PD 136450 and L-365,260 on pentagastrin-, histamine- and bethanechol-induced gastric acid secretion. 2. The novel CCKB/gastrin antagonists CI-988 and PD 136450, and L-365,260 dose-dependently inhibited pentagastrin-induced secretion. The ED50 value for PD 136450 was 0.05 mumol kg-1, the same following intravenous or subcutaneous administration. 3. CI-988 and PD 136450 administered subcutaneously at dose levels highly effective for antagonism of pentagastrin responses had no effect on basal acid secretion. 4. Ranitidine inhibited pentagastrin-, bethanechol-, and histamine-induced acid secretion, whereas the CCKB/gastrin antagonists inhibited only the secretory response to pentagastrin. 5. The selective CCKA antagonist, devazepide, was inactive at up to 300 mumol kg-1 i.p. against the three stimulants of acid secretion. 6. CI-988 and PD 136450 will be useful research tools with which to investigate the role of CCKB/gastrin receptors in gastric acid secretion and the trophic activities of gastrin and cholecystokinin (CCK) on the gastrointestinal tract.

Animals↗
PubMed1991

Metatarsal head excision for rheumatoid arthritis. 4-year follow-up of 68 feet with and without hallux fusion.

Thirty-four painful deformed rheumatoid feet treated by excision of all five metatarsal heads were compared with 34 similar feet in which the lesser metatarsal heads were excised and the first metatarsophalangeal joint was arthrodesed. In the latter group, one third had failure of fusion of the hallux, and this produced the worst results. Metatarsalgia and plantar callosities were more common after excision arthroplasty, but shoe fitting and correction of deformity were better in this group. However, the results were more variable in the fusion group, and the complication and reoperation rates were higher. For this reason, excision arthroplasty, rather than fusion of the hallux, is recommended when the lesser metatarsal heads are removed.

Adult↗
PubMed1991

Impurity and danger: the need for new barriers and bridges in the prevention of sexually-transmitted disease in the Tari Basin, Papua New Guinea.

The Huli of the Tari Basin have a serious problem with the spread of STDs following the opening of the Highlands Highway from Mendi in the early 1980s. Huli territory is now the site of huge mineral exploration and development and fears are held by health officers that the diseases may soon become an epidemic. The likelihood of AIDS entering the area in the near future provides a further need for all available barriers to be erected against the diseases and new bridges constructed to better health practices. Traditional teaching among the Huli emphasized the polluting effects of sexual contact. Missionary activity and the increasing commercialization of Huli culture have combined to weaken deterrents to premarital and extramarital sexual experiences. Traditionally, men believed that dangers of pollution came from two sources; women and outsiders. Only the Huli elders held these beliefs in the 1990s and little heed is paid to their warnings. Travel for work or pleasure has greatly increased among Huli men who no longer fear the outside world but rather wish to be part of it. Thus the traditional barriers which minimized infectious diseases have been demolished. The traditional Huli health-belief model is discussed and the possibility of harnessing traditional taboos in the fight against the spread of STDs is explored.

Adult↗
PubMed1991

Opioid binding sites in the guinea pig and rat kidney: radioligand homogenate binding and autoradiography.

The specific binding of the selective mu-, delta-, and kappa-opioid ligands [3H][D-Ala2,MePhe4,Gly-ol5]enkephalin ([3H] DAGOL), [3H][D-Pen2,D-Pen5]enkephalin ([3H]DPDPE), and [3H]U69593, respectively, to crude membranes of the guinea pig and rat whole kidney, kidney cortex, and kidney medulla was investigated. In addition, the distribution of specific 3H-opioid binding sites in the guinea pig and rat kidney was visualized by autoradiography. Homogenate binding and autoradiography demonstrated the absence of mu- and kappa-opioid binding sites in the guinea pig kidney. No opioid binding sites were demonstrable in the rat kidney. In the guinea pig whole kidney, cortex, and medulla, saturation studies demonstrated that [3H]DPDPE bound with high affinity (KD = 2.6-3.5 nM) to an apparently homogeneous population of binding sites (Bmax = 8.4-30 fmol/mg of protein). Competition studies using several opioid compounds confirmed the nature of the delta-opioid binding site. Autoradiography experiments demonstrated that specific [3H]DPDPE binding sites were distributed radially in regions of the inner and outer medulla and at the corticomedullary junction of the guinea pig kidney. Computer-assisted image analysis of saturation data yielded KD values (4.5-5.0 nM) that were in good agreement with those obtained from the homogenate binding studies. Further investigation of the delta-opioid binding site in medulla homogenates, using agonist ([3H]DPDPE) and antagonist ([3H]diprenorphine) binding in the presence of Na+, Mg2+, and nucleotides, suggested that the delta-opioid site is linked to a second messenger system via a GTP-binding protein. Further studies are required to establish the precise localization of the delta binding site in the guinea pig kidney and to determine the nature of the second messenger linked to the GTP-binding protein in the medulla.

Analgesics↗
PubMed1990

The anticonvulsant action of CI-977, a selective kappa-opioid receptor agonist: a possible involvement of the glycine/NMDA receptor complex.

The selective kappa-opioid receptor agonist CI-977, stereoselectively antagonised clonic seizures induced by slow i.v. infusion of N-methyl-DL-aspartate in the mouse. It was found to be more efficacious and 10-fold more potent than the competitive N-methyl-D-aspartic acid receptor antagonist CPP (3-(+/-)-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid). The anticonvulsant action of CI-977 was antagonised by norbinaltorphimine indicating a specific interaction with the kappa-receptor. The effect of CI-977 but not that of CPP was also antagonised by the glycine/NMDA receptor agonist D-serine. These results provide evidence for a possible interaction between the kappa-receptor and the glycine/NMDA receptor.

Animals↗
PubMed1990

Characterization of kappa-opioid receptors in the guinea-pig ileum.

Equilibrium binding saturation studies with [3H]bremazocine, under mu- and delta-suppressed conditions and [3H]U69593 have demonstrated that both radioligands bind with high affinity to an apparently homogeneous population of binding sites in the guinea-pig ileum longitudinal muscle-myenteric plexus preparation. In competition studies, the absolute affinities and slopes of the inhibition curves for several unlabelled ligands against [3H]bremazocine were not significantly different to those against [3H]U69593 and were consistent with binding to the kappa-opioid binding site. In the intestinal layers underlying the longitudinal muscle-myenteric plexus [3H]bremazocine, under kappa-selective conditions, recognized both a high and low affinity site. In contrast, [3H]U69593 bound to a homogeneous population of binding sites. The [3H]U69593 binding site and the [3H]bremazocine high affinity site demonstrated comparable characteristics to the single, kappa site identified in the longitudinal muscle layer. The nature of the low affinity site was not investigated due to difficulties associated with low specific binding, and its significance therefore remains to be investigated.

Animals↗
PubMed1990

PD117302, a selective non-peptide opioid kappa agonist, protects against NMDA and maximal electroshock convulsions in rats.

The pharmacological profile of PD117302 was studied in three rat models of experimental seizures. It was determined that PD117302 is a potent and efficacious anticonvulsant against NMDA (ED50 = 0.27 mg/kg, i.v.) and MES (ED50 = 16.3 mg/kg, s.c.), but not flurothyl, convulsions. Its anticonvulsant profile was dose- and time-dependent, stereospecific and sensitive to naloxone and the selective kappa opioid antagonist nor-binaltorphimine. Given these findings, we suggest that PD117302 acts via the kappa receptor to modulate seizure protection. Furthermore, in view of its marked ability to block NMDA excitotoxicity (including lethality) it seems possible that this drug, or related compounds, may have potential therapeutic utility as a neuroprotective agent.

Animals↗