Salt chamber treatment is ineffective in treating eosinophilic inflammation in asthma

BACKGROUND

We have shown that salt chamber treatment reduces airway hyper-responsiveness as an add-on therapy in adult asthmatics on inhaled corticosteroids.

METHODS

We assessed whether this effect is due to the suppression of eosinophilic airway inflammation. Thirty-nine adult asthmatics on inhaled corticosteroids were randomized to receive active salt chamber treatment with low-salt treatment 6.6 mg/m(3) (n = 14), high-salt treatment 10.8 mg/m(3) (n = 15) or placebo 0.3 mg/m(3) (n = 10) 10 times in a 2 weeks' period in a double-blind manner.

RESULTS

The level of induced sputum eosinophilic cationic protein μg/l, was 3070 before and 4651 after the low-salt treatment period, on average. In the high-salt treatment group, it was 12 192 μg/l vs 11 803 and in the placebo group 3942 vs 4144, respectively. Salt chamber treatment had no effect on sputum eosinophil or neutrophil cell numbers.

CONCLUSIONS

The reduction in hyper-responsiveness observed in the previous study is probably not due to the effect on eosinophilic inflammation.

Intranasal diamorphine for acute sickle cell pain

The painful crisis is the commonest acute presentation of sickle cell disease (SCD), yet effective pain control in hospital is often delayed, inadequate and dependent on injected opiates. Intranasal diamorphine (IND) has been used in paediatric emergency departments for management of acute pain associated with fractures, but the analgesic effect is short lived. We evaluated its efficacy and safety when given in combination with intravenous or oral morphine for rapid analgesia for children presenting to our emergency department with painful crisis of SCD. In phase 1, nine patients received IND plus intravenous morphine. In phase 2, 13 received IND plus oral morphine. There was a rapid improvement in pain score; the proportions in severe pain at t = 0, 15, 30 and 120 minutes in phase 1 were 78%, 11%, 0% and 11%, respectively; in phase 2, 77%, 30%, 15% and 0%, respectively. There were no serious side effects and questionnaire scores indicated that children found IND effective and acceptable. IND can be recommended for acute control of sickle pain in children presenting to hospital.

The effect of salt chamber treatment on bronchial hyperresponsiveness in asthmatics

BACKGROUND

Randomized controlled trials are needed to evaluate the effects of complementary treatments in asthma. This study assessed the effect of salt chamber treatment as an add-on therapy to low to moderate inhaled steroid therapy in asthma patients with bronchial hyperresponsiveness (BHR).

METHODS

After a 2-week baseline period, 32 asthma patients who exhibited BHR in the histamine inhalation challenge were randomized: 17 to 2-week active treatment, during which salt was fed to the room by a salt generator, and 15 to placebo. The salt chamber treatment lasted 40 min and was administered five times a week.

RESULTS

Median provocative dose causing a decrease of 15% in Fev(1) (PD(15)FEV(1)) [corrected] increased significantly in the active group (P = 0.047) but not in the placebo group. The difference in changes between the active and placebo groups was significant (P = 0.02). Nine patients (56%) in the active group and two patients (17%) in the placebo group exhibited at least one doubling dose decrease in BHR (P = 0.040). Six patients (38%) in the active group and none in the placebo group became non-hyperresponsive (P = 0.017). Neither the peak expiratory flow (PEF) values measured just before and after the treatment, nor FEV(1) values measured before the histamine challenges, changed. The reduction in BHR was not caused by changes in the baseline lung function.

CONCLUSIONS

Salt chamber treatment reduced bronchial hyperresponsiveness as an add-on therapy in asthmatics with a low to moderate dose of inhaled steroids. The possibility that salt chamber treatment could serve as a complementary therapy to conventional medication cannot be excluded.

Autoradiographic evaluation of [11C]vinpocetine binding in the human postmortem brain

The main objective ofthe study was to evaluate with autoradiographic technique whether or not [11C]vinpocetine, a compound widely used in the prevention and treatment of cerebrovascular diseases (Cavinton, Gedeon Richter Ltd., Budapest), binds to specific sites in the human brain in post mortem human brain sections. Binding was assessed under four conditions: the incubation was performed using Tris-HCl buffer with or without the addition of salts (0.1% (weight/vol) ascorbic acid, 120 mM NaCl, 5 mM KCl, 2 mM CaCl2 and 1 mM MgCl2), with or without the addition of excess (10 microM) unlabelled vinpocetine. Measurements on digitized autoradiograms indicated that [11C]vinpocetine labelled all grey matter areas in the human brain to a similar extent and no significantly heterogeneous binding could be demonstrated among cortical or subcortical regions. The addition of excess unlabelled vinpocetine lowered the binding slightly in all regions. Although these results indicate that [11C]vinpocetine does not bind to human brain transmitter receptors or transporters with a high affinity (Ki < 10 nM), it cannot be ruled out that the compound binds to receptors and/or transporters with lower affinity.

PET studies on the brain uptake and regional distribution of [11C]vinpocetine in human subjects

OBJECTIVES

Vinpocetine is a compound widely used in the prevention and treatment of cerebrovascular diseases. It is still not clear whether the drug has a direct and specific effect on neurotransmission or its effects are due to extracerebral actions, such as changes in cerebral blood flow. The main objective of the present investigation was to determine the global uptake and regional distribution of radiolabelled vinpocetine in the human brain in order to explore whether it may have direct central nervous system effects.

MATERIAL AND METHODS

Three healthy subjects were examined with positron emission tomography and [11C]vinpocetine. The regional uptake was determined in anatomically defined volumes-of-interest. The fractions of [11C]vinpocetine and labelled metabolites in plasma were determined using high pressure liquid chromatography.

RESULTS

The uptake of [11C]vinpocetine in brain was rapid and 3.7% (mean; n = 4) of the total radioactivity injected was in brain 2 min after radioligand administration. The uptake was heterogeneously distributed among brain regions. When compared with the cerebellum, an a priori reference region, the highest regional uptake was in the thalamus, upper brain stem, striatum and cortex. Following an initial peak, the total concentration of radioactivity in blood was relatively stable with time, whereas the concentration of the unchanged compound decreased with time in an exponential manner.

CONCLUSION

Vinpocetine, administered intravenously in humans, readily passes the blood-brain barrier and enters the brain. Its regional uptake and distribution in the brain is heterogeneous, indicating binding to specific sites. The brain regions showing increased uptake in the human brain correspond to those in which vinpocetine has been shown to induce elevated metabolism and blood flow. These observations support the hypothesis that vinpocetine has direct neuronal actions in the human brain.

Penile involvement in Henoch-Schonlein purpura

The authors report the case of a four-year-old boy who, having been diagnosed as having uncomplicated Henoch-Schonlein purpura, returned five days later with a new crop of lesions and sudden onset of engorgement and oedema of the penis. Testicular and scrotal involvement has been well documented in Henoch-Schonlein purpura but involvement of the penis alone has not been widely reported.

New halogenated [11C]WAY analogues, [11C]6FPWAY and [11C]6BPWAY--radiosynthesis and assessment as radioligands for the study of brain 5-HT1A receptors in living monkey

[Carbonyl-(11)C]WAY-100635 ([(11)C]WAY) is an established radioligand for the study of brain serotonin(1A) (5-HT(1A)) receptors in living animals and humans with positron emission tomography (PET). There is a recognised need to develop halogenated ligands for 5-HT(1A) receptors, either for labelling with longer-lived fluorine-18 for more widespread application with PET or with iodine-123 for application with single photon emission tomography (SPET). Here we used autoradiography and PET to assess two new halogenated analogues of WAY, namely 6BPWAY and 6FPWAY [N-(2-(1-(4-(2-methoxyphenyl)-piperazinyl)ethyl))-N-(2-(6-bromo-/fluoro-pyridinyl))cyclohexanecarboxamide] as prospective radioligands, initially using carbon-11 as the radiolabel. Labelling of 6BPWAY and 6FPWAY with carbon-11 was accomplished by acylation of the corresponding secondary amine precursors with [carbonyl-(11)C]cyclohexanecarbonyl chloride. After incubation of human brain crysections with [(11)C]6BPWAY or [(11)C]6FPWAY, the highest accumulation of radioactivity was observed in cortical areas and the hippocampal formation. Both radioligands had high nonspecific binding. There was a rapid accumulation of radioactivity in the monkey brain after intravenous injection of [(11)C]6BPWAY and [(11)C]6FPWAY. High accumulation of radioactivity was observed in the frontal and temporal cortex and the raphe nuclei, areas known to contain a high density of 5-HT(1A) receptors. The ratios of radioactivity in receptor-rich temporal cortex to that in receptor-poor cerebellum at peak equilibrium were 1.9 (at 10 min) and 3.0 at (at 20 min) for [(11)C]6BPWAY and [(11)C]6FPWAY, respectively. In pretreatment experiments with high doses of unlabelled WAY, the level of radioactivity in the frontal and temporal cortex and the raphe nuclei was reduced to the same level as in the cerebellum. Radioactive metabolites of [(11)C]6FPWAY appeared at a rate similar to those for [(11)C]WAY, with 17% of the radioactivity in plasma represented by unchanged radioligand after 40 min. Radioactive metabolites of [(11)C]6BPWAY appeared much more slowly. At 40 min after injection 45% of the radioactivity in plasma still represented unchanged radioligand. The results indicate that 6-pyridinyl radiohalogented analogues of WAY are new leads to radioligands for PET or SPET.

Carbon-11 pb-12: an attempt to visualize the dopamine d(4) receptor in the primate brain with positron emission tomography

The dopamine D(4) receptor (D(4)R) is expressed in low density in various extrastriatal brain regions. This receptor subtype is discussed in relation to the pathophysiology and treatment of schizophrenia but no selective positron emission tomography (PET) ligand is available to date to study the distribution in vivo. The arylpiperazine derivative N-[2-[4-(4-chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide (PB-12) is a novel, high-affinity ( K(i)=0.040 nM) and selective D(4)R ligand. We radiolabeled PB-12 with carbon-11 (t(1/2) 20.4 min) by O-methylation of the corresponding desmethyl analogue N-[2-[4-(4-chlorophenyl)piperazin-1-yl]ethyl]-3-hydroxybenzamide (LM-190) with [(11)C]methyl triflate. Derivative LM-190 was prepared by condensing 3-hydroxybenzoic acid with the appropriate amine. For the radiolabeling, the incorporation yield was >90% and the total synthesis time including high performance liquid chromatography (HPLC) purification was about 35 min. The specific radioactivity of [(11)C]PB-12 at time of injection was 67-118 GBq x micromol(-1). PET studies in a cynomolgus monkey showed a high uptake and widespread distribution of radioactivity in the brain, including the neocortex and thalamus. About 40% of total radioactivity in plasma represented unchanged radioligand at 60 min after injection as determined by HPLC. Pretreatment with the D(4)R ligand 3-[[4-(4-chlorophenyl)piperazin-1-yl]methyl]-1H-pyrollo[2,3-b]pyridine (L-745,870) prior to radioligand injection failed to demonstrate receptor-specific binding in the monkey brain. Furthermore, the brain radioactivity distribution was left unaffected by pretreating with unlabeled PB-12. This failure to detect a D(4)R-specific signal may be related to a very low density of the D(4)R in primate brain, insufficient binding affinity of the radioligand, and a high background of nonspecific binding. It can be concluded from these findings that [(11)C]PB-12 is not suitable to visualize the D(4)R in the primate brain with PET.

Use of PET and the radioligand [carbonyl-(11)C]WAY-100635 in psychotropic drug development

Positron-emission tomography (PET) provides potential in neuropsychiatric drug development by expanding knowledge of drug action in the living human brain and reducing time consumption and costs. The 5-hydroxytryptamine(1A) (5-HT(1A)) receptor is of central interest as a target for the treatment of anxiety, depression, and schizophrenia. Research on the clinical significance of the 5-HT(1A) receptor now benefits from the highly selective radioligand [carbonyl-(11)C]WAY-100635 (WAY) for quantitative determination of 5-HT(1A) receptors in the primate and human brain in vivo using PET. In this paper, three studies are reviewed to demonstrate the suitability of WAY as radioligand for quantification of central 5-HT(1A) receptors in brain and as an applicable tool for drug development. In the first study a monkey model was used to characterize WAY binding. It was confirmed that the reference ligand 8-OH-DPAT and psychoactive drugs such as buspirone and pindolol occupies 5-HT(1A) receptors in the primate brain. Pindolol is an beta-adrenoreceptor antagonist with a high affinity to 5-HT(1A) receptors. This drug has been suggested in combination with selective serotonin reuptake inhibitors for the treatment of depression and was given to healthy males in the second study. Pindolol induced a marked inhibition of central 5-HT(1A) receptors as calculated by the ratio-analysis method and simplified reference tissue model, 2 h after administration of 10 mg as a single oral dose. This observation suggests that pindolol may have a role for the suggested potentiation of selective serotonin reuptake inhibitor treatment of depression. The third study was on robalzotan (NAD-299), a recently developed 5-HT(1A) receptor antagonist and putative drug with implications for the treatment of depression. In the cynomolgus monkey brain, robalzotan in the dose range 2-100 microg/kg IV occupied 5-HT(1A) receptors in a dose-dependent and saturable manner with a maximal calculated occupancy of 70-80%. The relationship between robalzotan plasma concentration and 5-HT(1A) receptor occupancy could be described by a hyperbolic function that was used to guide the selection of appropriate doses in man. In a subsequent PET study of robalzotan binding to 5-HT(1A) receptors in the living human brain, similar results have been replicated recently. These studies reviewed here illustrate and corroborate that quantitative neuroimaging of receptor binding has potential for the evaluation and dose finding of new central nervous system drugs.

Radioligands for the study of brain 5-HT(1A) receptors in vivo--development of some new analogues of way

[Carbonyl-(11)C]WAY-100635 (WAY) has proved to be a very useful radioligand for the imaging of brain 5-HT(1A) receptors in human brain in vivo with positron emission tomography (PET). WAY is now being applied widely for clinical research and drug development. However, WAY is rapidly cleared from plasma and is also rapidly metabolised. A comparable radioligand, with a higher and more sustained delivery to brain, is desirable since these properties might lead to better biomathematical modelling of acquired PET data. There are also needs for other types of 5-HT(1A) receptor radioligands, for example, ligands sensitive to elevated serotonin levels, ligands labelled with longer-lived fluorine-18 for distribution to "satellite" PET centres, and ligands labelled with iodine-123 for single photon emission computerised tomography (SPECT) imaging. Here we describe our progress toward these aims through the exploration of WAY analogues, including the development of [carbonyl-(11)C]desmethyl-WAY (DWAY) as a promising, more brain-penetrant radioligand for PET imaging of human 5-HT(1A) receptors, and (pyridinyl-6-halo)-analogues as promising leads for the development of radiohalogenated ligands.

Carbon-11 epidepride: a suitable radioligand for PET investigation of striatal and extrastriatal dopamine D2 receptors

Epidepride [(S)-(-)-N-([1-ethyl-2-pyrrolidinyl]methyl)-5-iodo-2,3-dimethoxybenza mide] binds with a picomolar affinity (Ki = 24 pM) to the dopamine D2 receptor. Iodine-123-labeled epidepride has been used previously to study striatal and extrastriatal dopamine D2 receptors with single photon emission computed tomography (SPECT). Our aim was to label epidepride with carbon-11 for comparative quantitative studies between positron emission tomography (PET) and SPECT. Epidepride was synthesized from its bromo-analogue FLB 457 via the corresponding trimethyl-tin derivative. In an alternative synthetic pathway, the corresponding substituted benzoic acid was reacted with the optically pure aminomethylpyrrolidine-derivative. Demethylation of epidepride gave the desmethyl-derivative, which was reacted with [11C]methyl triflate. Total radiochemical yield was 40-50% within a total synthesis time of 30 min. The specific radioactivity at the end of synthesis was 37-111 GBq/micromol (1,000-3,000 Ci/mmol). Human postmortem whole-hemisphere autoradiography demonstrated dense binding in the caudate putamen, and also in extrastriatal areas such as the thalamus and the neocortex. The binding was inhibited by unlabeled raclopride. PET studies in a cynomolgus monkey demonstrated high uptake in the striatum and in several extrastriatal regions. At 90 min after injection, uptake in the striatum, thalamus and neocortex was about 11, 4, and 2 times higher than in the cerebellum, respectively. Pretreatment experiment with unlabeled raclopride (1 mg/kg) inhibited 50-70% of [11C]epidepride binding. The fraction of unchanged [11C]epidepride in monkey plasma determined by a gradient high performance liquid chromatography (HPLC) method was about 30% of the total radioactivity at 30 min after injection of [11C]epidepride. The availability of [11C]epidepride allows the PET-verification of the data obtained from quantitation studies with SPECT.

PET examination of three potent cocaine derivatives as specific radioligands for the serotonin transporter

Several positron emission tomography (PET) radioligands based on the aryl tropane structure have been used for studies on monoamine reuptake sites. RTI-364, RTI-330, and RTI-357 (3-beta-(4'-n-propyl-,4'-iso-propyl-, and 4'-iso-propenyl-phenyl)nortropane-2-beta-carboxylic acid methyl ester) are three recently synthesized cocaine analogues with higher affinity for the serotonin (5-HTT) than the dopamine transporter (DAT). Unlabelled RTI-364 and RTI-330 were prepared in a two-step synthesis. The key step was the addition of the appropriate propyl Grignard reagent to anhydroecgonine methyl ester. RTI-357 was prepared in a three-step synthesis with a palladium-catalyzed coupling reaction of beta-CIT and isopropenylzinc bromide as key step. Hydrolysis of the ester functions gave the carboxylic acid analogues of RTI-364, RTI-330, and RTI-357, which were labelled with 11C using [11C]methyl iodide in dimethyl formamide (DMF) and tetrabutylammonium hydroxide (TBAH) as base. All three compounds entered the monkey brain in a high degree (approximately 5-10%). There was a low uptake of [11C]RTI-364 in serotonin-rich brain areas, whereas [11C]RTI-330 and [11C]RTI-357 showed a marked uptake of radioactivity in the thalamus and the brainstem, regions known to contain serotonin transporters. Transient equilibrium was reached at 15 and 40 min for [11C]RTI-330 and [11C]RTI-357, respectively. After pretreatment with citalopram, the ratio of radioactivity in the thalamus and the brainstem to the cerebellum were markedly reduced for [11C]RTI-357 but not for [11C]RTI-330. The results indicate that [11C]RTI-357 is a potential PET radioligand for quantitation of the serotonin reuptake site.

Radiosynthesis and autoradiographic evaluation of [11C]NAD-299, a radioligand for visualization of the 5-HT1A receptor

The selective 5-HT1A receptor antagonist NAD-299 ([R]-3-N,N-dicyclobutylamino-8-fluoro-3,4- dihydro-2H-1-benzopyran-5-carboxamide) was labeled with the positron-emitting radionuclide carbon-11. The radioligand was synthesized from NAD-195 ([R]-3-N,N-dicyclobutylamino-8-fluoro-5-trifluoromethylsulfonyl oxy-3,4- dihydro-2H-1-benzopyran) in two radiochemical steps. A palladium-catalyzed reaction of NAD-195 and [11C]cyanide was followed by hydrolysis of the carbon-11-labeled nitrile intermediate with basic hydrogen peroxide. The total radiochemical yield, based on [11C]CO2 and corrected for decay, was 20-40%. The specific radioactivity was 24 GBq/mumol (900 Ci/mmol) at end of synthesis, with a radiochemical purity better than 99% and a total synthesis time of 40-45 min. Autoradiographic examination of [11C]NAD-299 binding in human brain postmortem demonstrated high binding in hippocampus, raphe nuclei, and neocortex. The binding in the hippocampus was higher than in the neocortex. Within the hippocampus, the densest binding was observed in the CA1 region. [11C]NAD-299 binding was inhibited by addition of the 5-HT1A receptor ligands WAY-100635, pindolol, (+/-)-8-OH-DPAT, 5-HT, and buspirone, leaving a low background of nonspecific binding. The results indicate that [11C]NAD-299 binds specifically to 5-HT1A receptors in the human brain in vitro and is a potential radioligand for positron emission tomography (PET) examination of 5-HT1A receptors in vivo.

Carbon-11-NNC 112: a radioligand for PET examination of striatal and neocortical D1-dopamine receptors

The aim of this work was to explore the potential of a selective D1-dopamine receptor antagonist as a new radioligand for PET examination of striatal and neocortical D1-dopamine receptors.

METHODS

The active (+)- and inactive (-)-enantiomers of [11C]NNC 112 were radiolabeled using the N-methylation approach and were examined by PET in cynomolgus monkeys and healthy men. Metabolite levels in plasma were measured by gradient high-performance liquid chromatography (HPLC).

RESULTS

N-methylation of the corresponding desmethyl precursors with [11C]methyl triflate gave high total radiochemical yield (50%-60%) and specific radioactivity (110 GBq/micromol). (+)-[11C]NNC 112 binding in cynomolgus monkeys was 5.77+/-0.31 and 2.36+/-0.14 times higher in the striatum and neocortex, respectively, than in the cerebellum at a transient equilibrium that appeared 40-50 min after injection. The binding of (+)-[11C]NNC 112 is stereoselective, because the brain distribution of the inactive (-)-enantiomer was on an equally low level for all brain regions. Displacement and pretreatment experiments using unlabeled SCH 23390 and ketanserin confirms that (+)-[11C]NNC 112 binds specifically and reversibly to D1-dopamine receptors. The radioactivity ratios of the striatum, frontal cortex and nucleus accumbens to the cerebellum were 3.8-4.0, 1.7-2.0 and 2.8-3.1, respectively, at a transient equilibrium that appeared 40-50 min after injection in four healthy human subjects. Linear graphical analysis gave distribution volume ratios of 3.9 and 1.5 in the putamen and frontal cortex, respectively. The fraction of the total radioactivity in human plasma representing unchanged (+)-[11C]NNC 112 was 85% at 5 min and 25% at 75 min after injection.

CONCLUSION

(+)-[11C]NNC 112 should be a useful PET radioligand for quantitative examination of not only striatal but neocortical D1-dopamine receptors in man.

Effects of inhalation and cutaneous exposure to styrene on drug metabolizing enzymes in the rat

The effects of inhalation and cutaneous exposure to styrene on the drug metabolizing enzymes were studied in the rat. Rats were exposed eight hours per day, for seven successive days to 450 ppm concentration of styrene or received one cutaneous dose of styrene daily for seven consecutive days (0.5 and 3.0 g/kg). The animals were killed one day after the last dose. Styrene inhalation increased the activities of epoxide hydrase and UDPglucuronosyltransferase (4-methylumbelliferone as substrate) in liver (1.5- and 1.7-fold, respectively). Ethoxycoumarin deethylation was enhanced 1.7-fold in the kidney. The content of cytochrome P-450 in the liver and the activities of NADPH cytochrome c-reductase, benzpyrene hydroxylase and glutathione S-transferase in the liver and kidney were not altered. No changes in the enzyme activities were detected in the lung. Styrene depressed the epoxide hydrase activity in liver when administered cutaneously. No signs of enzyme induction could be seen after cutaneous administration.