Development and operation of the defence COVID-19 lab as a SARS-CoV-2 diagnostic screening capability for UK military personnel

BACKGROUND

In the face of the COVID-19 pandemic, the Defence Science and Technology Laboratory (Dstl) and Defence Pathology combined to form the Defence Clinical Lab (DCL), an accredited (ISO/IEC 17025:2017) high-throughput SARS-CoV-2 PCR screening capability for military personnel.

LABORATORY STRUCTURE AND RESOURCE

The DCL was modular in organisation, with laboratory modules and supporting functions combining to provide the accredited SARS-CoV-2 (envelope (E)-gene) PCR assay. The DCL was resourced by Dstl scientists and military clinicians and biomedical scientists.

LABORATORY RESULTS

Over 12 months of operation, the DCL was open on 289 days and tested over 72 000 samples. Six hundred military SARS-CoV-2-positive results were reported with a median E-gene quantitation cycle (Cq) value of 30.44. The lowest Cq value for a positive result observed was 11.20. Only 64 samples (0.09%) were voided due to assay inhibition after processing started.

CONCLUSIONS

Through a sustained effort and despite various operational issues, the collaboration between Dstl scientific expertise and Defence Pathology clinical expertise provided the UK military with an accredited high-throughput SARS-CoV-2 PCR test capability at the height of the COVID-19 pandemic. The DCL helped facilitate military training and operational deployments contributing to the maintenance of UK military capability. In offering a bespoke capability, including features such as testing samples in unit batches and oversight by military consultant microbiologists, the DCL provided additional benefits to the UK Ministry of Defence that were potentially not available from other SARS-CoV-2 PCR laboratories. The links between Dstl and Defence Pathology have also been strengthened, benefitting future research activities and operational responses.

Evidence-Based Guideline on Laparoscopy in Pregnancy: Commissioned by the British Society for Gynaecological Endoscopy (BSGE) Endorsed by the Royal College of Obstetricians & Gynaecologists (RCOG)

Laparoscopy is widely utilised to diagnose and treat acute and chronic, gynaecological and general surgical conditions. It has only been in recent years that laparoscopy has become an acceptable surgical alternative to open surgery in pregnancy. To date there is little clinical guidance pertaining to laparoscopic surgery in pregnancy. This is why the BSGE commissioned this guideline. MEDLINE, EMBASE, CINAHL and the Cochrane library were searched up to February 2017 and evidence was collated and graded following the NICE-approved process. The conditions included in this guideline are laparoscopic management of acute appendicitis, acute gall bladder disease and symptomatic benign adnexal tumours in pregnancy. The intended audience for this guideline is obstetricians and gynaecologists in secondary and tertiary care, general surgeons and anaesthetists. However, only laparoscopists who have adequate laparoscopic skills and who perform complex laparoscopic surgery regularly should undertake laparoscopy in pregnant women, since much of the evidence stems from specialised centres.

A time-driven, activity-based costing methodology for determining the costs of red blood cell transfusion in patients with beta thalassaemia major

OBJECTIVES

To describe the methodology to estimate the total cost of administration of a single unit of red blood cells (RBC) in adults with beta thalassaemia major in an Australian specialist haemoglobinopathy centre.

BACKGROUND

Beta thalassaemia major is a genetic disorder of haemoglobin associated with multiple end-organ complications and typically requiring lifelong RBC transfusion therapy. New therapeutic agents are becoming available based on advances in understanding of the disorder and its consequences. Assessment of the true total cost of transfusion, incorporating both product and activity costs, is required in order to evaluate the benefits and costs of these new therapies.

METHODS

We describe the bottom-up, time-driven, activity-based costing methodology used to develop process maps to provide a step-by-step outline of the entire transfusion pathway. Detailed flowcharts for each process are described. Direct observations and timing of the process maps document all activities, resources, staff, equipment and consumables in detail. The analysis will include costs associated with performing these processes, including resources and consumables. Sensitivity analyses will be performed to determine the impact of different staffing levels, timings and probabilities associated with performing different tasks.

RESULTS

Thirty-one process maps have been developed, with over 600 individual activities requiring multiple timings. These will be used for future detailed cost analyses.

CONCLUSIONS

Detailed process maps using bottom-up, time-driven, activity-based costing for determining the cost of RBC transfusion in thalassaemia major have been developed. These could be adapted for wider use to understand and compare the costs and complexities of transfusion in other settings.

Links between temperamental dimensions and brain monoamines in the rat

In 27 female Wistar rats, the authors obtained composite scores on harm avoidance and novelty seeking, as well as 57 measures of monoamines and metabolites from 10 different brain regions. A multivariate regression method was used to discover associations between individual differences in temperament and neurochemistry. Harm-avoidant subjects had low levels of striatal dopamine and high levels of cortical norepinephrine and amygdaloid 5-hydroxyindoleacetic acid. High novelty-seeking scores were linked to low levels of brainstem serotonin and dopamine and to low levels of 5-hydroxyindoleacetic acid in amygdala and accumbens. Moreover, rats scoring high on novelty seeking had higher-than-average levels of norepinephrine in the thalamus and amygdala and of serotonin in the amygdala.

A behavioural pattern analysis of hypoglutamatergic mice--effects of four different antipsychotic agents

In a hypoglutamatergic rodent model, we have observed certain behaviours that might have relevance for the cognitive impairments seen in autism and schizophrenia. Thus, hypoglutamatergic mice show defective habituation, impaired attention, a meagre behavioural repertoire and a general behavioural primitivization. The aim of the present study was to characterise and quantify changes in movement pattern in mice rendered hypoglutamatergic by means of MK-801 treatment, using an automated video tracking system. Further, the effects of four different antipsychotic drugs, the classical neuroleptic haloperidol, the atypical antipsychotic clozapine, the DA D2/5-HT2A antagonist risperidone and the selective 5-HT2A-receptor antagonist M100907, were compared with respect to effects on NMDA antagonist-induced movement pattern alterations. We found that each receptor antagonist had a unique effect on the MK-801-induced behavioural primitivization. Haloperidol was unable to affect the monotonous behaviour induced by MK-801, while risperidone, clozapine and M100907 produced movement patterns of high intricacy.

Interactions between monoamines, glutamate, and GABA in schizophrenia: new evidence

In spite of its proven heuristic value, the dopamine hypothesis of schizophrenia is now yielding to a multifactorial view, in which the other monoamines as well as glutamate and GABA are included, with a focus on neurotransmitter interactions in complex neurocircuits. The primary lesion(s) in schizophrenia does not necessarily involve any of these neurotransmitters directly but could deal with a more general defect, such as a faulty connectivity of developmental origin. Nevertheless, a precise identification of neurotransmitter aberrations in schizophrenia will probably provide clues for a better understanding of the disease and for the development of new treatment and prevention strategies.

Production of free radicals measured by spin trapping during operations for stenosis of the carotid artery

OBJECTIVES

To analyse production of free radicals during operations for stenosis of the internal carotid artery.

SETTING

University hospital, Sweden.

SUBJECTS

10 patients operated on for carotid artery stenosis.

INTERVENTIONS

Blood samples were repeatedly drawn from the sigmoid sinus through a catheter in the internal jugular vein on the same side, before, during, and after clamping of the internal carotid artery. OXANOH was added to the blood samples in vitro and the radical production calculated from the amount oxidised to OXANO as electron spin resonance.

MAIN OUTCOME MEASURES

The relation between radical production and certain clinical variables investigated by partial least squares regression analysis.

RESULTS

There were several significant relations. High systolic blood pressure and advanced age were associated with low, and severe degree of stenosis with increased, free radical production. Certain anaesthetic drugs as well as blood variables also influenced the production of radicals.

CONCLUSIONS

The technique used seems to offer the possibility to find and study methods to reduce free radical production during this kind of operation.

Activation of a Plasmodium falciparum cdc2-related kinase by heterologous p25 and cyclin H. Functional characterization of a P. falciparum cyclin homologue

Several Plasmodium falciparum genes encoding cdc2-related protein kinases have been identified, but the modalities of their regulation remains largely unexplored. In the present study, we investigated the regulation in vitro of PfPK5, a putative homologue of Cdk1 (cdc2) in P. falciparum. We show that (i) PfPK5 is efficiently activated by heterologous (human) cyclin H and p25, a cyclin-like molecule that specifically activates human Cdk5; (ii) the activated enzyme can be inhibited by chemical Cdk inhibitors; (iii) Pfmrk, a putative P. falciparum homologue of the Cdk-activating kinase, does neither activate nor phosphorylate PfPK5; and (iv) PfPK5 is able to autophosphorylate in the presence of a cyclin. Taken together, these results suggest that the regulation of Plasmodium Cdks may differ in important aspects from that of their human counterparts. Furthermore, we cloned an open reading frame encoding a novel P. falciparum protein possessing maximal homology to cyclin H from various organisms, and we show that this protein, called Pfcyc-1, is able to activate recombinant PfPK5 in vitro with an efficiency similar to that of human cyclin H and p25. This work opens the way to the development of screening procedures aimed at identifying compounds that specifically target the parasite Cdks.

Neurotransmitter interactions in schizophrenia-therapeutic implications

The search for new and improved antipsychotic agents has increased in intensity during the past five years. The era of searching for non-toxic copies of clozapine has been followed by several different lines of research, some of which pursue the traditional dopamine track, although at a higher level of sophistication, whereas others focus on other neurotransmitters, such as serotonin and glutamate. Emerging knowledge about the interactions between different neurotransmitters in complex neurocircuits opens up possibilities for achieving antipsychotic activity by interfering with many different neurotransmitters. Most intriguing is the finding in animal experimental models, indicating that it should be possible to alleviate psychotic conditions by stabilizing rather than paralyzing neurocircuits, thus avoiding the risk of motor and mental side effects of the currently used drugs. Among these new classes, dopaminergic stabilizers and 5-HT2A receptor antagonists appear to offer the most promise at present. In a longer perspective, drugs interfering with glutamate function via different mechanisms may also turn out to be useful, especially in the control of negative symptoms.

Network interactions in schizophrenia - therapeutic implications

Research into the role of neurotransmitters and neural networks in the pathogenesis of schizophrenia has been remarkably successful in recent years. The hypothesis postulating a dopamine dysfunction, which has for a long time been supported only by indirect evidence, has received direct support by means of sophisticated imaging techniques. Interactions between dopamine and several other neurotransmitters in complex neural networks have been revealed, largely thanks to the advent of an array of new pharmacological probes. Two major pharmacological models of schizophrenia, based on hyperdopaminergia and hypoglutamatergia, respectively, are ready for clinical testing. In addition, the hypothesis of network stabilization as a major therapeutic strategy in psychiatry and neurology has now reached the 'proof-of-concept' level. From a therapeutic perspective, several ongoing and forthcoming clinical trials, using drugs acting on dopaminergic, serotonergic and glutamatergic receptors, give rise to optimism.

Neurotransmitter interactions in schizophrenia--therapeutic implications

The search for new and improved antipsychotic agents has escalated during the past five years. The era of searching for non-toxic copies of clozapine has been followed by several different lines of research, some of which pursue the traditional dopamine track, although at a higher level of sophistication, whereas others focus on other neurotransmitters, such as serotonin and glutamate. Emerging knowledge about the interactions between different neurotransmitters in complex neurocircuits opens up possibilities for achieving antipsychotic activity by interfering with many different neurotransmitters. Most intriguing is the finding in animal experimental models, indicating that it should be possible to alleviate psychotic conditions by stabilizing rather than paralyzing neurocircuits, thus avoiding the risk of motor and mental side effects of the currently used drugs. Among these new classes dopaminergic stabilizers and 5-HT2A receptor antagonists seem to offer most promise at present. In a longer perspective, drugs interfering with glutamate function via different mechanisms may also turn out to be useful, especially in the control of negative symptoms.

The 5-HT2A receptor antagonist M100907 is more effective in counteracting NMDA antagonist- than dopamine agonist-induced hyperactivity in mice

The purpose of the present study was to compare the effectiveness of the selective 5-HT2A antagonist M100907 in different psychosis models. The classical neuroleptic haloperidol was used as reference compound. Two hyperdopaminergia and two hypoglutamatergia mouse models were used. Hyperdopaminergia was produced by the DA releaser d-amphetamine or the DA uptake inhibitor GBR 12909. Hypoglutamatergia was produced by the un-competitive NMDA receptor antagonist MK-801 or the competitive NMDA receptor antagonist D-CPPene. M100907 was found to counteract the locomotor stimulant effects of the NMDA receptor antagonists MK-801 and D-CPPene, but spontaneous locomotion, d-amphetamine- and GBR-12909-induced hyperactivity were not significantly affected. Haloperidol, on the other hand, antagonized both NMDA antagonist- and DA agonist-induced hyperactivity, as well as spontaneous locomotion in the highest dose used. Based on the present and previous results we draw the conclusion that 5-HT2A receptor antagonists are particularly effective against behavioural anomalies resulting from hypoglutamatergia of various origins. The clinical implications of our results and conclusions would be that a 5-HT2A receptor antagonist, due to i a the low side effect liability, could be the preferable treatment strategy in various disorders associated with hypoglutamatergia; such conditions might include schizophrenia, childhood autism and dementia disorders.

A glutamatergic deficiency model of schizophrenia

Although the presence of hyperdopaminergia has been demonstrated in the brains of people with schizophrenia, at least in some circumstances, other neurotransmitters are important in this disorder, and a glutamatergic deficiency model of schizophrenia is proposed. It is suggested that the amount of sensory input allowed to reach the cerebral cortex is restricted by an inhibitory effect of the striatal complexes on the thalamus, thereby protecting it from being overwhelmed. Several strands of evidence are presented to support the concept that a weakened glutamatergic tone increases the risk of sensory overload and of exaggerated responses in the monoaminergic systems that could result in psychosis.

Effects of the substituted (S)-3-phenylpiperidine (-)-OSU6162 on PET measurements of [11C]SCH23390 and [11C]raclopride binding in primate brains

The substituted (S)-3-phenylpiperidine (-)-OSU6162 belongs to a novel class of functional modulators of dopaminergic systems. In vivo, (-)-OSU6162 has a unique stabilising profile on dopaminergic functions. In vitro this compound exhibits low affinity for the dopamine D2 receptor, but due to its similarity to neuroleptics on brain dopaminergic neurochemistry and different postsynaptic effects it has been characterised as a preferential dopamine autoreceptor antagonist. To further clarify the effects of (-)-OSU6162 on the postjunctional nigrostriatal dopaminergic system, dopamine receptor binding was measured in rhesus monkeys (Macaca mulatta) by positron emission tomography (PET) using the D1 and D2 dopamine receptor radioligands [11C]SCH23390 and [11C]raclopride respectively, before and during continuous intravenous infusions of(-)-OSU6162. Additionally, the test-retest variability of sequential [11C]SCH23390 scans was estimated. Following the administration of (-)-OSU6162, [11C]raclopride binding in striatum was dose-dependently decreased with a 76% reduction occurring after 3.0 mg/kg per h continuous infusion. Whereas (-)-OSU6162 in the lower doses had no effect on [11C]SCH23390 binding, the highest dose, 3.0 mg/kg per h, increased [11C]SCH23390 binding, which may indicate a potentiating effect on D1 dopamine receptor mediated functions. Thus, in contrast to the conditions in vitro, (-)-OSU6162 produces a high displacement of raclopride from D2 receptors in vivo.

Rodent data and general hypothesis: antipsychotic action exerted through 5-Ht2A receptor antagonism is dependent on increased serotonergic tone

The locomotor stimulation induced by the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 (dizocilpine) in mice was regarded as a model of at least some aspects of schizophrenia. The serotonin synthesis inhibitor dl-p-chlorophenylalanine (PCPA) was used to evaluate the involvement of endogenous serotonin in (a) the induction of MK-801-induced hyperlocomotion in NMRI mice, and (b) the inhibition of MK-801-induced hyperlocomotion by each of five monoaminergic antagonists (M100907, clozapine, olanzapine, raclopride, SCH23390). Further, brain monoaminergic biochemistry was characterised in rats and mice after various drug treatments. PCPA pretreatment did not significantly reduce MK-801-induced hyperlocomotion in any of the experiments performed; however in a meta-analysis of six experiments, the locomotion displayed by MK-801-treated animals was diminished 17% by PCPA pretreatment. The selective 5-HT2A receptor antagonist M100907 exerted a dose-dependent inhibition of MK-801-induced hyperlocomotion. This effect was abolished in mice pretreated with PCPA, but could be restored in a dose-dependent manner by restitution of endogenous 5-HT by means of 5-hydroxytryptophan (5-HTP). On the other hand, the inhibition of MK-801-induced hyperlocomotion exerted by the selective dopamine D-2 receptor antagonist raclopride or the dopamine D-1 receptor antagonist SCH23390 was unaffected by PCPA pretreatment. The antipsychotics clozapine and olanzapine displayed a split profile. Hence, the inhibitory effect on MK-801-induced hyperlocomotion exerted by low doses of these compounds was diminished after PCPA pretreatment, while inhibition exerted by higher doses was unaffected by PCPA. These results suggest that (1) MK-801-induced hyperlocomotion is accompanied by an activation of, but is not fully dependent upon, brain serotonergic systems. (2) In the hypoglutamatergic state induced by MK-801, endogenous serotonin exerts a stimulatory effect on locomotion through an action at 5-HT2A receptors, an effect that is almost completely counterbalanced by a concomitant inhibitory impact on locomotion, mediated through stimulation of serotonin receptors other than 5-HT2A receptors. M100907, by blocking 5-HT2A receptors, unveils the inhibitory effect exerted on locomotion by these other serotonin receptors. (3) Dopamine D-2 receptor antagonistic properties of antipsychotic compounds, when they come into play, override 5-HT2A receptor antagonism. Possible implications for the treatment of schizophrenia with 5-HT2A receptor antagonists are discussed. It is hypothesized that treatment response to such agents is dependent on increased serotonergic tone.

Effects of the substituted (S)-3-phenylpiperidine (-)-OSU6162 on PET measurements in subhuman primates: evidence for tone-dependent normalization of striatal dopaminergic activity

(-)-OSU6162 is a substituted (S)-3-phenylpiperidine derivative which exhibits some affinity to the dopamine D2 receptor family. In vivo, the compound displays a unique normalizing profile on psychomotor activity by an intriguing mixture of stimulatory and inhibitory properties. In the present investigation, some of the effects of (-)-OSU6162 on central dopaminergic function were studied by positron emission tomography (PET) and L-[11C]DOPA in anaesthetized female rhesus monkeys. (-)-OSU6162 displayed a dopaminergic tone-dependent effect with a reduction in the striatal L-[11C]DOPA influx rate in monkeys with high baseline values and an increased striatal L-[11C]DOPA influx rate in animals with low baseline values. Infusion of (-)-OSU6162 for a whole day resulted in a stable effect with no evidence of tolerance. (-)-OSU6162 also stabilized dopaminergic function by attenuating the upregulation of the striatal L-[11C]DOPA influx rate which has previously been shown to occur following 6R-BH4 or 6R-BH4 + L-tyrosine infusions. This "Protean" effect of (-)-OSU6162 on the striatal dopaminergic function corresponds to previous behavioral observations in intact animals and demonstrates a true functional correlation to the measures obtained with L-[11C]DOPA and PET. The normalizing and stabilizing profile of (-)-OSU6162 should be of value in treating a variety of disorders where an underlying dysregulation or disruption of dopaminergic function can be assumed.

MK-801-induced hyperlocomotion: differential effects of M100907, SDZ PSD 958 and raclopride

The influence of three selective monoamine receptor antagonists on spontaneous locomotion and on the hyperlocomotion induced by the un-competitive N-methyl-D-aspartate (NMDA) receptor antagonist [+]-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]-cyclohepten-5,10-imine hydrogen maleate (MK-801; dizocilpine) was investigated. The selective and potent 5-hydroxytryptamine (5-HT)2A receptor antagonist R(+)-alpha(2,3-dimethoxyphenyl)-1-[2(4-fluorophenyl)ethyl)]-4-piperidine -methanol (MDL100,907; M100907) displayed a clear-cut selectivity for reduction of MK-801-induced as compared to spontaneous locomotion, in that the former was dose-dependently (0.001, 0.01, 0.1 mg/kg i.p.) blocked and even totally abolished by the highest dose, while the latter was only modestly affected. Even at high doses of M100907 (up to 9 mg/kg i.p.), spontaneous locomotion was not reduced below 40% of control. The selective dopamine D1 receptor antagonist (-)-[4aR, 10 aR]-1,2,3,4,4a,5,10,10a-octahydro-4-(4-chloro-2-methyl-phenyl)-1-methyl- benzo[g]quinoxaline-6-ol (SDZ PSD 958; 0.017, 0.15, 1.35 mg/kg i.p.) decreased both spontaneous and MK-801-induced locomotion with a slight preference for the latter; spontaneous locomotion was dose-dependently diminished to approx. 10% of controls (at 8 mg/kg i.p.). The dopamine D2 receptor antagonist raclopride ([(-)-(S)-3,5-dichloro-N-((1-ethyl-2-pyrrolidinyl) methyl)-6-methoxy-salicylamide tartrate]; 0.11, 0.33, 1.0 mg/kg i.p.) reduced both MK-801-induced and spontaneous locomotion to a similar extent. An orthogonal matrix experimental design, and multiple regression, were used to evaluate the effects of several combinations of different doses of the 5-HT2A receptor antagonist and the dopamine D1 receptor antagonist. No synergistic actions on reduction of spontaneous or MK-801-induced locomotion were detected between M100907 and SDZ PSD 958. If the hyperlocomotion elicited by acutely administered MK-801 is a valid model of at least some aspects of schizophrenia, these results indicate that the 5-HT2A receptor antagonist M100907 will have efficacy in treating this condition. The lack of effect on spontaneous locomotion, suggests that M100907, compared to dopamine receptor antagonists, will be less prone to induce psychomotor side-effects. Ongoing clinical studies will hopefully give the answers in the near future.

The apparent antipsychotic action of the 5-HT2a receptor antagonist M100907 in a mouse model of schizophrenia is counteracted by ritanserin. (Rapid communication)

The apparent antipsychotic action of the selective 5-HT2a receptor antagonist M100907 in MK-801-treated NMRI mice was shown to be markedly counteracted by the 5-HT2a/2c receptor antagonist ritanserin. The mechanism of action and potential implications are discussed.

Synthesis of [11C-methyl]-(-)-OSU6162, its regional brain distribution and some pharmacological effects of (-)-OSU6162 on the dopaminergic system studied in the rhesus monkey by positron emission tomography

The labelling of the presynaptic dopamine receptor antagonist (-)-OSU6162, ((S)-(-)-3-(3-(methylsulfonyl)phenyl)-1-propylpiperidine) was performed by an alkylation with [11C]methyl iodide of the thio anion (-)-OSU1281, followed by a selective oxidation to the corresponding methyl sulfone, [11C-methyl]-(-)-OSU6162. The total radiochemical yield calculated from the produced [11C]carbon dioxide to final product was about 25% and the time of synthesis was in the range of 40 min from end of bombardment. The synthesis of the precursor, (-)-OSU1281, was performed from (-)-3PPP in a three-step synthesis. The regional brain distribution of (-)-OSU6162 radiolabelled with 11C was studied in rhesus monkeys by means of positron emission tomography, PET. [11C-Methyl]-(-)-OSU6162 was rapidly and uniformly distributed to gray matters of the brain, and no decrease of radioactivity uptake in the brain was seen after pretreatment with 1 to 3 mg/kg/h of (-)-OSU6162. The effect of doses of 1 to 3 mg/kg/h of (-)-OSU6162 on the dopamine binding was studied by PET using [11C-methyl]raclopride. Radioactivity in the striatum was significantly and dose-dependently decreased by (-)-OSU6162 (r = 0.88), supporting competition with dopamine for selective binding to dopamine receptors.

Neurotransmitter aberrations in schizophrenia: new perspectives and therapeutic implications

The dopamine hypothesis has dominated schizophrenia research for decades but is now yielding to a more diversified view, where the interaction of several neurotransmitters in complex circuitries is under scrutiny. Especially, glutamatergic and serotonergic mechanisms are attracting attention. However, the role of dopamine also needs further exploration and may still turn out to have novel therapeutic applications. In the present minireview an attempt is made to integrate preclinical and clinical data on neurotransmitter aberrations in schizophrenia and to discuss their therapeutic implications.

Effects on locomotor activity after local application of (+)-UH232 in discrete areas of the rat brain

The preferential dopamine autoreceptor, and slightly D3 preferring, antagonist (+)-UH232 (cis-(+)-(1S,2R)-5-methoxy-1-methyl-2-(n-dipropylamino) tetralin) increases locomotor activity and synaptic dopamine release in the nucleus accumbens and striatum after systemic administration to the rat. As shown in this study, (+)-UH232, was unable to produce an increase in locomotor activity measured for 60 minutes after local administration into the terminal or somato-dendritic regions of the mesolimbic dopamine pathways or into the lateral ventricle. Instead, a dose dependent decrease of spontaneous locomotor activity after local application (0.05-50.0 nmol/side) of (+)-UH232 into the nucleus accumbens, was seen. A similar reduction in locomotor activity was produced by the classical dopamine antagonist raclopride. Analysis of the dose*time interactions on locomotor activity did, however, indicate that there is a significant dose*time interaction after local application of (+)-UH232 into the lateral ventricle and VTA. Raclopride, on the other hand, produced only a weak time dependent effect in the VTA. The potential problem of Leao's spreading depression in micro-injection experiments were considered, however, spreading depression does not seem to influence the effects of (+)-UH232 locally applied into the nucleus accumbens. In conclusion, both (+)-UH232 and raclopride produced a dose dependent decrease in spontaneous locomotor activity when examined as the total activity count over 60 minutes after local application into the N Acc.

Concurrent locomotor stimulation and decrease in dopamine release in rats and mice after treatment with the competitive NMDA receptor antagonists D-CPPene and CGS 19755

The present study was aimed at investigating the effects of the competitive N-methyl-D-aspartate (NMDA) receptor antagonists D-CPPene (3-(2-carboxypiperazine-4-yl)-propenyl-1-phosphonic acid) and CGS 19755 (cis-4-(phosphonomethyl)piperidine-2-carboxylic acid) on dopamine (DA) transmission and motor activity in mice and rats. As measures of DA release we used mouse brain 3-methoxytyramine (3-MT) levels, and indirect estimate of DA release, and striatal dialysate measures of DA in conscious and freely moving rats by means of microdialysis. To obtain additional information about monoaminergic neurotransmission, brain tissue levels of DA, DOPAC, HVA, 5-HT and 5-HIAA were measured in both mice and rats. The animals were sacrificed at the time when NMDA antagonist-induced locomotor stimulation was maximal. In mice, D-CPPene and CGS 19755 decreased striatal 3-MT levels, whereas, in general, 3-MT levels in the limbic forebrain were not significantly altered. Treatment with CGS 19755 decreased rat striatal dialysate levels of DA but increased 5-HIAA at time points when locomotor activity was increased. D-CPPene and CGS 19755 have been observed to produce psychotic symptoms in man. The present study suggests that these symptoms are not a result of an increase in central dopamine release.

On the quantitative structure-activity relationships of meta-substituted (S)-phenylpiperidines, a class of preferential dopamine D2 autoreceptor ligands: modeling of dopamine synthesis and release in vivo by means of partial least squares regression

The quantitative structure-activity relationship between physicochemical properties and effects on dopamine (DA) synthesis and release in the rat brain, in a series of meta-substituted (S)-phenylpiperidines, has been investigated by means of partial least squares regression (PLS). The effect on DA synthesis caused by the drugs, in both non-pretreated and reserpine-pretreated rats, was assessed by measurements of tissue levels of L-DOPA accumulated in the striatum following treatment with a decarboxylase inhibitor. Assessment of effects on DA release was performed by analysis of perfusates collected from implanted microdialysis probes. The numerical characterization of the variation in physicochemical features of the phenylpiperidines used in the regression modeling was accomplished by using common tabulated aromatic and aliphatic substituent constants in combination with a set of property descriptors derived from molecular mechanics and semiempirical calculations. It was found that the biochemical responses could be accurately predicted by the regression models based on these molecular feature measures. The molecular features exerting influence on DA synthesis were found to be markedly different from those influencing DA release. This finding is discussed in terms of the possible existence of a dopamine receptor-mediated DA release-controlling mechanism, which may not involve the synthesis regulating DA D2 autoreceptor. Some findings regarding the impact of the piperidine N substituent on agonist properties of the drugs are reported. The regression models were also used for guidance in the search for a phenylpiperidine with a lower intrinsic activity, at the DA D2 type autoreceptor, than the partial DA agonist preclamol (3).

Neil F. Curtis

No Abstract Available.

Behavioral and neurochemical data suggest functional differences between dopamine D2 and D3 receptors

In an in vitro model for mitogenic activity in cloned Chinese hamster ovary (CHO) cells expressing rat dopamine D2 or D3 receptors, the EC50D2/EC50D3 ratios for the agonists, apomorphine, (+)-3-hydroxy-N-n-propyl-phenylpiperidine ((+)-3-PPP), quinpirole, R-(+)-7-hydroxy-2-(di-n-propylamino)tetralin (R-(+)-7-OH-DPAT) and pramipexole (SND919) were found to be 0.36, 0.41, 1.3, 3.7 and 7.0, respectively. In locomotor activity experiments with actively exploring rats, the more dopamine D3 preferring agonists, R-(+)-7-OH-DPAT and pramipexole, were most efficacious to reduce locomotion. The hypoactivity was also observed at doses that did not affect brain dopamine synthesis rate (DOPA accumulation) or release (measured in in vivo dialysis experiments). In contrast, for apomorphine, (+)-3-PPP and quinpirole there was a closer correlation between doses that reduced exploratory activity and doses that reduced brain dopamine release and synthesis. The present data support the hypothesis that the functional dopamine D3 receptor is a postsynaptic receptor inhibitory on rat locomotion.

Evidence for biochemical heterogeneity in schizophrenia: a multivariate study of monoaminergic indices in human post-mortal brain tissue

A previously performed post-mortem study comparing monoaminergic indices in the brains of 14 schizophrenic patients and 10 patients with psychosis not diagnosed as schizophrenia, with age-matched control cases without any known neuropsychiatric illness, was re-investigated, using multivariate analysis. The monoaminergic patterns showing up in this analysis suggested the existence of at least two different forms of the disease, both of which could be distinguished from the controls as well as from each other. One of the schizophrenic groups consisted of paranoid cases, and had a relatively mild family history, whereas the other group, mainly consisting of hebephrenic cases, had a severe family history. The former group showed low levels of dopamine and high levels of serotonergic precursor and metabolite, whereas the latter group in some respects tended to show the opposite aberrations. Neuroleptic treatment did not seem to account for the different biochemical profiles, unless one assumes that this treatment can cause completely different monoaminergic aberrations in different individuals. Instead, one could argue that the different biochemical profiles found are characteristic of the disease.

Substituted (S)-phenylpiperidines and rigid congeners as preferential dopamine autoreceptor antagonists: synthesis and structure-activity relationships

A series of (S)-phenylpiperidines in which the substituents on the aromatic ring and nitrogen have been varied has been prepared. They have been evaluated pharmacologically to explore the importance of these substituents for the interaction with central dopamine (DA) receptors. On the basis of biochemical and behavioral data in rats, several of these compounds are characterized as centrally acting DA autoreceptor antagonists. (S)-Phenylpiperidines having an aromatic substituent with a high group dipole moment in the 3-position, i.e., meta with respect to the piperidine ring, and being N-substituted with a propyl group were found to be highly active in vivo on the synthesis and turnover of dopamine. However, they do not induce strong hypoactivity or catalepsy. Interestingly, the most active compounds in vivo were found to display only low affinity for DA D2 and D3 receptors in vitro. In addition, 7-triflate-substituted octahydrobenzo[f]quinolines and 6-triflate-substituted hexahydro-1H-benz[e]indoles have been prepared and pharmacologically evaluated. The trans isomers of these rigid structures were found to display a pharmacological profile similar to that of the flexible phenylpiperidines. The corresponding cis isomers were found to be inactive in vivo.

Differential effects of dopamine D2 and D3 receptor antagonists in regard to dopamine release, in vivo receptor displacement and behaviour

To establish possible functional differences between the dopamine D2 and D3 receptor we investigated the relation between the ability, for a set of nine mixed dopamine D2 and D3 receptor antagonists, to displace N, N-dipropyl-2-amino-5,6-dihydroxy tetralin (DP-5,6-ADTN) from striatal binding sites and the subsequent behavioural consequences in vivo. Dopamine D2 receptor preferring antagonists are powerful displacers of DP-5,6-ADTN from the striatum. Maximal displacement is followed by strong hypomotility. Displacement of the agonist by the D3 preferring antagonist U99194A is only partial and results in synergistic increases in locomotor activity. Superimposing haloperidol upon GBR12909 leads to a synergistic increase in striatal dialysate dopamine concentrations. This effect is absent when combining GBR12909 with the putative D3 antagonist U99194A. These data give support for the hypothesis that the dopamine D3 receptor is functionally relevant at the postsynaptic level. Here, in contrast to the D2 receptor, it is proposed to exert an inhibitory influence on psychomotor functions.

Locomotor inhibition by the D3 ligand R-(+)-7-OH-DPAT is independent of changes in dopamine release

The dopamine D3 preferring ligand R-(+)-7-OH-DPAT induced strong hypolocomotion in rats. Doses producing reduction of locomotion failed to affect dopamine release or synthesis rate. These data support the hypothesis that the dopamine D3 receptor is a postsynaptic receptor with an inhibitory influence on rat locomotor activity.

Intracerebral infusion of (+)-AJ76 and (+)-UH232: effects on dopamine release and metabolism in vivo

The dopamine D3- and autoreceptor preferring antagonists (+)-AJ76 and (+)-UH232 were administered locally in the striatum and the nucleus accumbens. Their effects on dialysate dopamine and 3,4-di-hydroxyphenylacetic acid (DOPAC) were measured and compared with the effects of raclopride. (+)-AJ76 and (+)-UH232 but not raclopride seem to interact primarily with dopamine receptors in the terminal regions of the A9 and A10 dopaminergic fibers to exert their maximal effect on dopamine release in vivo. Thus, (+)-AJ76 and (+)-UH232 seem to recruit different dopamine receptor populations as compared to raclopride. Though the dopamine receptor antagonist-induced effects on dopamine release seem to be mediated mainly by dopamine receptors in the terminal areas, the effects on DOPAC by the different antagonists seem to be mediated mainly via effects elsewhere, presumably at the somatodendritic autoreceptors. Thus, it is suggested that the regulation of extracellular dopamine and DOPAC after treatment with dopamine receptor antagonists are subjected to different control mechanisms.

Substituted 3-phenylpiperidines: new centrally acting dopamine autoreceptor antagonists

The (+)-and (-)-enantiomer of compounds 4 and 5 were synthesized and tested for central dopamine (DA) receptor stimulating activity, using biochemical and behavioral tests in rats. Based on the available data the (-)-enantiomers of 4 and 5 are characterized as centrally acting DA autoreceptor antagonists with oral activity. They display a similar pharmacological profile as the prototype DA autoreceptor antagonists (+)-1 and (+)-2 and show a certain preference for the D3 DA receptor antagonist binding site.

The dopamine D3 receptor and autoreceptor preferring antagonists (+)-AJ76 and (+)-UH232; a microdialysis study

The in vivo neurochemical profiles of haloperidol, raclopride and the dopamine D3 and autoreceptor preferring dopamine receptor antagonists (+)-UH232 and (+)-AJ76 on dopamine release and metabolism in the dorsal striatum and in the nucleus accumbens are described. It is shown that both (+)-UH232 and especially (+)-AJ76 have different effects on brain dialysate dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) as compared to haloperidol or raclopride. It is suggested that the relative increase in dialysate dopamine over the relative increase in DOPAC is a neurochemical fingerprint, unique for different dopamine receptor antagonists. As a consequence the increased release and metabolism of dopamine after systemic administration of dopamine receptor antagonists may be controlled by different receptors and different dopamine antagonists can partly distinguish between these receptors. This may be due to their different interactions with different dopamine D2 type receptors. It is finally concluded that (+)-UH232 and especially (+)-AJ76 seem to prefer release regulating autoreceptors at the level of the axon terminals.

The dopamine D3-receptor: a postsynaptic receptor inhibitory on rat locomotor activity

We report on the pharmacological effects of the 20 fold D3 vs. D2 dopamine receptor preferring compound U99194A. It is shown that U99194A increases rat locomotor activity at doses that do not increase release or utilisation of dopamine in the striatum or the nucleus accumbens significantly. The data do not support any direct agonist action of U99194A at dopamine receptors. It is suggested that U99194A can antagonise a population of postsynaptic dopamine receptors involved in the suppression of some aspects of psychomotor activity. These postsynaptic receptors presumably belong to the D3 receptor subtype.

The influence of serotoninergic drugs on dopaminergic neurotransmission in rat substantia nigra, striatum and limbic forebrain in vivo

The effects of serotoninergic drugs on dopaminergic neurotransmission in the substantia nigra, the striatum and the limbic forebrain of rat have been investigated. The accumulation of 3-methoxytyramine (3-MT) following inhibition of monoamine oxidase with pargyline was used as an indirect measure of dopamine (DA) activity in vivo. The effects of the following serotoninergic drugs were tested: the 5-HT1A receptor agonist 8-OH-DPAT, the 5-HT1B receptor agonist trifluoromethyl-phenylpiperazine (TFMPP), CGS 12066 B and RU 24969, the 5-HT1A/1B antagonist (+/-)pindolol, the 5-HT2/1C receptor antagonist ritanserin, the 5-HT2/1C receptor agonist DL-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), the 5-HT3 receptor antagonist BRL 43694, the unselective 5-HT receptor antagonist methiothepin, and carbidopa + L-5-hydroxytryptophan (L-5-HTP) to achieve a general, unselective stimulation of multiple 5-HT receptors. In the substantia nigra, carbidopa + 5-HTP treatment increased the 3-MT accumulation by 26% and decreased the DA concentration to 67% of controls, tentatively suggesting a 5-HTP-induced displacement of nigral DA. A minor, non dose-related reduction in nigral 3-MT was seen after the 5-HT1A receptor agonist 8-OH-DPAT. None of the other serotonin receptor acting drugs induced any pronounced effect on the nigral 3-MT accumulation. Taken together, the findings provide little support for the idea that one single 5-HT receptor subtype serves a modulatory function on DA activity in the substantia nigra. In the striatum and the limbic forebrain, trifluoromethyl-phenylpiperazine dose-dependently increased the 3-MT accumulation to maximally 200%-220% of controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased dopamine release by the autoreceptor antagonist (+)-AJ 76 is Ca2(+)-dependent

The effects of the preferential autoreceptor antagonist (+)-AJ 76 on dopamine release and metabolism were studied in the brain microdialysis model. The Ca2+ dependence of the effects of (+)-AJ 76 and d-amphetamine were compared. We found that (+)-AJ 76 increased the release and metabolism of dopamine and that the release was saturable. The release of dopamine by (+)-AJ 76 was dependent on extracellular Ca2+. However, the effects of (+)-AJ 76 on dopamine metabolism were independent of extracellular Ca2+. The effects of d-amphetamine on dopamine release and metabolism were independent of Ca2+. We conclude that the dopamine released by (+)-AJ 76 is dependent on neuronal impulse flow and that the dopamine released is of vesicular origin. The effects on dopamine metabolism and release may be exerted via different mechanisms. In contrast, the release and metabolism of dopamine by d-amphetamine were independent of impulse flow and extracellular Ca2+. We suggest that (+)-AJ 76 and d-amphetamine release dopamine from different pools.

The putatively antipsychotic agent amperozide produces behavioural stimulation in the rat. A behavioural and biochemical characterization

Amperozide (FG 5606; N-ethyl-4-[4',4'-bis(p-fluorophenyl)butyl]-1-piperazinecarboximide ) is a new putatively antipsychotic compound with a postulated 5-HT2 antagonistic profile. Somewhat surprisingly amperozide dose dependently induced a behavioural stimulation in reserpinized and in nonpretreated rats. The behaviour consisted of both forward and backward locomotion as well as forepaw circling and a grooming like behaviour. Since the behavioural pattern clearly differ from that produced by classical dopaminergic or serotonergic agonists (e.g. apomorphine or 8-hydroxy-2-(di-n-propylamino)tetralin, 8-OH-DPAT), and has not been previously reported, we decided to investigate the origin of this effect. In the behavioural paradigms it was not possible to antagonize the amperozide stimulation in reserpinized rats with the dopamine receptor blockers haloperidol, raclopride or R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1 H-3-benzazepine, SCH 23390. Neither the 5-HT2 receptor blocking agent ritanserin nor the tryptophan and tyrosine hydroxylase inhibitor DL-3,4-dihydroxy-phenyl-alpha-propylacetamide, H22/54, could block the motoric stimulation or the forepaw circling behaviour produced by amperozide. However, the noradrenaline synthesis inhibitor bis-(4-methyl-1-homopiperazinylthiocarbonyl)-disulfide, FLA 63, as well as the alpha-adrenoceptor antagonist phenoxybenzamine, could partly inhibit the locomotor stimulation. Hence, noradrenaline seems to be, at least in part, involved in the behavioural stimulatory effect of amperozide. Biochemically amperozide had no effect on the dopamine synthesis rate (DOPA formation) in normal or reserpinized animals in the striatal or the limbic brain regions. In reserpinized animals amperozide also failed to antagonize the decrease in DOPA formation after apomorphine and 3-hydroxy-benzylhydrazine HCl, NSD 1015, in these regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Random urine analyses from drug addicts in a methadone treatment programme

Random testing of urine from opiate addicts in the methadone treatment programme at the Drug Dependency Service, Brisbane Street, Sydney, was carried out for 18 months. Six samples from each of approximately 100 clients (that is, 580 specimens) have been analysed. It was found that clients receiving high methadone dosages (80 mg and over) used illegal opiates significantly less frequently than those on lower dosages. Furthermore, a decline in the use of illegal opiates and an increase in the proportion of "clear" urine specimens (that is, clear of all drugs except methadone) were indicators of the effectiveness of the methadone programme. It was concluded that urine testing was a useful and objective means of evaluating methadone or any other drug addiction treatment programme, and of monitoring what other drugs were being taken, both consciously or inadvertently in combinations. The results of urine testing can also be of value to counsellors in the therapeutic situation.