Appropriateness of acute-care antibiotic prescriptions for community-acquired infections and surgical antibiotic prophylaxis in England: analysis of 2016 national point prevalence survey data

BACKGROUND

Estimates of inappropriate prescribing can highlight key target areas for antimicrobial stewardship (AMS) and inform national targets.

OBJECTIVES

To (1) define and (2) produce estimates of inappropriate antibiotic prescribing levels within acute hospital trusts in England.

METHODS

The 2016 national Healthcare-Associated Infections (HAI), Antimicrobial Use (AMU) and AMS point prevalence survey (PPS) was used to derive estimates of inappropriate prescribing, focusing on the four most reported community-acquired antibiotic indications (CAIs) in the PPS and surgical prophylaxis. Definitions of appropriate antibiotic therapy for each indication were developed through the compilation of national treatment guidelines. A Likert-scale system of appropriateness coding was validated and refined through a two-stage expert review process.

RESULTS

Antimicrobial usage prevalence data were collected for 25,741 individual antibiotic prescriptions, representing 17,884 patients and 213 hospitals in England. 30.4% of prescriptions for the four CAIs of interest were estimated to be inappropriate (2054 prescriptions). The highest percentage of inappropriate prescribing occurred in uncomplicated cystitis prescriptions (62.5%), followed by bronchitis (48%). For surgical prophylaxis, 30.8% of prescriptions were inappropriate in terms of dose number, and 21.3% in terms of excess prophylaxis duration.

CONCLUSIONS

The 2016 prevalence of inappropriate antibiotic prescribing in hospitals in England was approximated to be 30.4%; this establishes a baseline prevalence and provided indication of where AMS interventions should be prioritized. Our definitions appraised antibiotic choice, treatment duration and dose number (surgical prophylaxis only); however, they did not consider other aspects of appropriateness, such as combination therapy - this is an important area for future work.

Development and implementation of a national antimicrobial stewardship surveillance system, with open access data sharing

BACKGROUND

Public Health England (PHE) developed an antimicrobial stewardship (AMS) surveillance system and conducted a national pilot to test the feasibility of centrally collecting data from AMS audits performed by NHS hospital trusts. The system was simplified, focusing on requirements of the NHS AMR CQUIN (Commissioning for Quality and Innovation; a financial incentive quality improvement scheme).

AIM

To present results and user feedback from the national pilot, and results from using the AMS surveillance system as part of the AMR CQUIN.

METHODS

An AMS surveillance system was developed and a national pilot conducted in which 33 NHS trusts submitted data and feedback on system utilization. The system was refined based on feedback and deployed nationally to collect AMS data for the 2016-17 AMR CQUIN.

FINDINGS

Most trusts participating in the pilot collected data on documentation of indication (90%). Fewer collected data on documenting review decisions at 48-72 h (36%). On average 83% of patients had an indication documented, whereas 71% had formal documentation of 48-72 h review. AMR CQUIN data were submitted by 88% of trusts for at least one quarter of 2016-17. Approximately 92% of prescriptions had an indication documented and 87.5% of prescriptions had evidence of review within 72 h; these increased by 7 and 10 percentage points respectively between the first and final quarters.

CONCLUSION

The AMS surveillance system allowed AMS audit data from NHS trusts in England to be collected centrally. PHE publishes these data openly online, on PHE Fingertips portal, a national public health data portal. The reported data highlight improvement in the percentage of antibiotic prescriptions with evidence of a documented review within 72 h.

The logistical management of tertiary urethral disease in the United Kingdom: Implications from an online audit of male reconstructive urethral surgery

Objective:

To determine those patient groupings, based on volume and risk, whose optimal urethral reconstructive management might be provided by a reorganisation of UK reconstructive surgeons.

Methods:

Between 2010 and 2017, ~689 men/year were enrolled onto an online audit platform collecting data about urethral reconstruction in the UK; this accrual was compared against hospital episode statistics (HES). The available workforce, and where this was based, was collected. Individual and institutional incumbent patient volumes, pathology, surgical complexity and outcomes from treatment were collated to stratify volume/risk groups.

Results:

More than 90% of all HES-recorded data were accrued, being provided by 50 surgeons at 39 operative sites. Most reconstructive surgery was provided at 10 centres performing >20 procedures/year. More than 50% of all interventions were of a high-volume low-risk type. Of activity, 32.3% was intermediate volume or moderate risk, and 12.5% of men presented for lower-volume or higher-risk procedures.

Conclusion:

Correlation of detailed volume/outcome data allows the definition of patient populations presenting for urethral reconstruction. Stratification of each group’s management, to optimise the surgical outcome, may be applied to a hierarchical service delivery model based on the complexity of the patient’s presenting urethral pathology.

Level of evidence:

Level IV

The mechanism of action of zopiclone

The mechanism of action of the cyclopyrrolone hypnotic drug zopiclone involves allosteric modulation of the GABAAreceptor. Zopiclone displaces the binding of [3H]-flunitrazepam with an affinity of 28 nM, and enhances the binding of the channel blocker [35S]-TBPS. The binding of zopiclone, unlike that of hypnotic benzodiazepines, is not facilitated by GABA. Zopiclone does not distinguish between GABAA receptors containing different α-subunits (BZ1and BZ2phenotype). Studies with protein-modifying agents (egdiethylpyrocarbonate) and photoaffinity labelling suggest that cyclopyrrolones bind to a domain on the GABAA receptor different from the benzodiazepine binding domain. The consequence of this interaction with the GABAAreceptor is to potentiate responses to GABA, as can be demonstrated by electrophysiological methods. Subchronic treatment of mice with high doses of zopiclone does not produce the changes in sensitivity of the GABAAreceptor that are observed with hypnotic benzodiazepines.

How are genetic test results being used by Australian life insurers?

In Australia, the USA and many Asian countries the life insurance industry is self-regulated. Individuals must disclose genetic test results known to them in applications for new or updated policies including cover for critical care, income protection and death. There is limited information regarding how underwriting decisions are made for policies with such disclosures. The Australian Financial Services Council (FSC) provided de-identified data collected on applications with genetic test result disclosure from its life insurance member companies 2010–2013 to enable repetition of an independent examination undertaken of applications 1999-2003: age; gender; genetic condition; testing result; decision-maker; and insurance cover. Data was classified as to test result alone or additional other factors relevant to risk and decision. Where necessary, the FSC facilitated clarification by insurers. 345/548 applications related to adult-onset conditions. The genetic test result solely influenced the decision in 165/345 applications: positive (n = 23), negative (n = 139) and pending (n = 3). Detailed analyses of the decisions in each of these result categories are presented with specific details of 11 test cases. Policies with standard decisions were provided for all negative test results with evidence of reassessment of previous non-standard decisions and 20/23 positive results with recognition of risk reduction strategies. Disclosure of positive results for breast/ovarian cancer, Lynch syndrome and hereditary spastic paraplegia, and three pending results, generated non-standard decisions. The examination demonstrates some progress in addressing concerns in regard to utilisation of genetic test information but the self-regulatory system in Australia only goes some way in meeting internationally recommended best practice.

The Prostate Health Index adds predictive value to multi-parametric MRI in detecting significant prostate cancers in a repeat biopsy population

Both multi-parametric MRI (mpMRI) and the Prostate Health Index (PHI) have shown promise in predicting a positive biopsy in men with suspected prostate cancer. Here we investigated the value of combining both tests in men requiring a repeat biopsy. PHI scores were measured in men undergoing re-biopsy with an mpMRI image-guided transperineal approach (n = 279, 94 with negative mpMRIs). The PHI was assessed for ability to add value to mpMRI in predicting all or only significant cancers (Gleason ≥7). In this study adding PHI to mpMRI improved overall and significant cancer prediction (AUC 0.71 and 0.75) compared to mpMRI + PSA alone (AUC 0.64 and 0.69 respectively). At a threshold of ≥35, PHI + mpMRI demonstrated a NPV of 0.97 for excluding significant tumours. In mpMRI negative men, the PHI again improved prediction of significant cancers; AUC 0.76 vs 0.63 (mpMRI + PSA). Using a PHI≥35, only 1/21 significant cancers was missed and 31/73 (42%) men potentially spared a re-biopsy (NPV of 0.97, sensitivity 0.95). Decision curve analysis demonstrated clinically relevant utility of the PHI across threshold probabilities of 5-30%. In summary, the PHI adds predictive performance to image-guided detection of clinically significant cancers and has particular value in determining re-biopsy need in men with a negative mpMRI.

Patient-Reported Outcomes after Monitoring, Surgery, or Radiotherapy for Prostate Cancer

BACKGROUND

Robust data on patient-reported outcome measures comparing treatments for clinically localized prostate cancer are lacking. We investigated the effects of active monitoring, radical prostatectomy, and radical radiotherapy with hormones on patient-reported outcomes.

METHODS

We compared patient-reported outcomes among 1643 men in the Prostate Testing for Cancer and Treatment (ProtecT) trial who completed questionnaires before diagnosis, at 6 and 12 months after randomization, and annually thereafter. Patients completed validated measures that assessed urinary, bowel, and sexual function and specific effects on quality of life, anxiety and depression, and general health. Cancer-related quality of life was assessed at 5 years. Complete 6-year data were analyzed according to the intention-to-treat principle.

RESULTS

The rate of questionnaire completion during follow-up was higher than 85% for most measures. Of the three treatments, prostatectomy had the greatest negative effect on sexual function and urinary continence, and although there was some recovery, these outcomes remained worse in the prostatectomy group than in the other groups throughout the trial. The negative effect of radiotherapy on sexual function was greatest at 6 months, but sexual function then recovered somewhat and was stable thereafter; radiotherapy had little effect on urinary continence. Sexual and urinary function declined gradually in the active-monitoring group. Bowel function was worse in the radiotherapy group at 6 months than in the other groups but then recovered somewhat, except for the increasing frequency of bloody stools; bowel function was unchanged in the other groups. Urinary voiding and nocturia were worse in the radiotherapy group at 6 months but then mostly recovered and were similar to the other groups after 12 months. Effects on quality of life mirrored the reported changes in function. No significant differences were observed among the groups in measures of anxiety, depression, or general health-related or cancer-related quality of life.

CONCLUSIONS

In this analysis of patient-reported outcomes after treatment for localized prostate cancer, patterns of severity, recovery, and decline in urinary, bowel, and sexual function and associated quality of life differed among the three groups. (Funded by the U.K. National Institute for Health Research Health Technology Assessment Program; ProtecT Current Controlled Trials number, ISRCTN20141297 ; ClinicalTrials.gov number, NCT02044172 .).

A Novel Gaba Receptor on Central Neurones

The features of γ-aminobutyric acid (GABA) as an inhibitory neurotransmitter are described, together with those of its receptor as defined by both iontophoretic and radiolabelled ligand binding techniques. Evidence is presented supporting the existence of a second GABA receptor at both peripheral nerve endings and within the CNS. At the classical receptor, GABA can produce a depolarisation of the ganglion cell body or mediate hyperpolarisation within the CNS by increasing membrane conductance to chloride ions. At this second receptor GABA acts in a bicuculline-insensitive manner to reduce neurotransmitter outflow.

Many GABA analogues active at the classical receptor are inactive at the second receptor but by contrast baclofen which is inactive at the classical receptor is a potent agonist at the novel site.

Risk profiles of prostate cancers identified from UK primary care using national referral guidelines

Objective:

Prostate cancer in the United Kingdom is mainly diagnosed from primary care referrals based on national guidelines published by the Department of Health. Here we investigated the characteristics of cancers detected through the use of these guidelines.

Methods:

A prospective two-centre study was established to assess men referred from the primary care based on the UK national guidelines.

Results:

The overall cancer detection rate was 43% (169 out of 397) with 15% (26 out of 169) of all cancers metastatic at presentation. Amongst 50–69-year-old men these rates were 34% (68 out of 200) and 15% (10 out of 68). Only 21% (25 out of 123) of men with local cancers had low-risk disease. In comparison to a historical cohort from 2001 (n=137) we found no overall differences in rates of metastatic disease, locally advanced tumours, or risk categories. Amongst 50–69-year-old men with local disease, however, we observed an increase in detection of low-risk cancers in a contemporary cohort (P=0.04). This was primarily because of the increased detection of low-stage organ-confined tumours in this group (P=0.02).

Conclusion:

Use of the UK prostate cancer guidelines detects a high proportion of clinically significant cancers. Use of the guidelines does not seem to have led to an overall change in the clinical characteristics of presenting cancers. There may, however, be a specific benefit in detecting more low-risk disease in younger men.

Potassium markedly potentiates the effect of veratridine on dopamine release from rat superfused striatal ribbons

The effects of veratridine-induced depolarization on [3H]dopamine ([3H]DA) release in the presence of a physiological (5 Mm) or a depolarizing (25 Mm) concentration of K+ were studied in-vitro in rat superfused striatal ribbons. A combination of the two depolarizing agents induced a marked potentiation in the overflow of [3H]DA, giving an overall 3- to 5-fold increase in veratridine activity. This potentiation was completely antagonized by tetrodotoxin (100 Nm). These studies indicated that K+-induced depolarization can increase the potency of veratridine in releasing dopamine from terminals.

A Rapid Filtration Assay for the Glycine Binding Site on the NMDA Receptor in Rat Cortical Membranes using [3H]Dichlorokynurenic Acid

A filtration binding assay using [3H]dichlorokynurenic acid to label the glycine binding site on the N-methyl-d-aspartic acid receptor has been evaluated on rat cortical membranes. This ligand binds to a single population of binding sites following mass action kinetics with a Kd of 29 Nm and a capacity of 5·73 pmol (mg protein)−1. The pharmacological specificity of the binding site is identical to that previously reported for this binding site using [3H]glycine as a radioligand. Agonists showed lower affinity and antagonists higher affinity when [3H]dichlorokynurenic acid was used compared with [3H]glycine. The higher affinity of [3H]dichlorokynurenic acid compared with [3H]glycine make it the more suitable compound with which to label the glycine site.

Autoimmune T cell responses to seminal plasma in chronic pelvic pain syndrome (CPPS)

The aetiology of chronic prostatitis is not understood. The aim of this study is to investigate an autoimmune hypothesis by looking for T cell proliferation in response to proteins of the seminal plasma. We studied peripheral blood mononuclear cell proliferation from 20 patients with chronic prostatitis and 20 aged-matched controls in response to serial dilutions of seminal plasma (SP) from themselves (autologous SP) and from a healthy individual without the disease (allo-SP). We found that the patients have a statistically greater lymphocyte proliferation to autologous SP at the 1/50 dilution on day 6 compared to controls (P = 0 x 01). They also have a greater proliferation to allo-SP on both day 5 (P = 0 x 001) and day 6 (P = 0 x 01) at the same dilution. Using a stimulation index (SI) of 9 to either autologous SP or allo-SP on day 6 at the 1/50 dilution as a definition of a proliferative response to SP, then 13/20 patients as compared to 3/20 controls showed a proliferative response to SP (P = 0 x 003, Fishers exact test). These data support an autoimmune hypothesis for chronic prostatitis.

Animal models of amyotrophic lateral sclerosis

Animal models of human disease are important in unravelling the pathophysiology of the condition, for exploring the natural history of disease and for evaluating potential therapies. The development of animal models of human neurodegenerative disease such as ALS is particularly challenging, given the paucity of knowledge of their aetiology and the organizational specificity of the human motor system. Nonetheless, a range of spontaneously occurring, experimentally produced, or genetically engineered models of ALS are now available. Although not always a perfect replica of the ALS disease, these models are shown to be of outstanding importance for investigations of the mechanisms of dysfunction/death of motor neurons in vivo. This is particularly true for the transgenic mouse models expressing superoxide dismutase or cytoskeletal proteins. This approach has provided an unparalleled opportunity for testing of potential pharmacological or gene therapies, and it can be expected that the results of these studies will be translated into the clinical advances of the next years.

An evidence-based approach to the treatment of prostatitis: is it possible?

The classification of prostatitis has been re-evaluated, and the National Institutes of Health (NIH) has defined the separate groups more thoroughly. Furthermore, the development of the NIH chronic prostatitis symptom index (CPSI) has allowed the symptoms to be measured and the effect of interventions calculated. A search of the literature finds that the quality of treatment trials in prostatitis is poor and the level of evidence for many of the existing strategies is lacking; there is a total absence of any meta-analyses of randomized controlled trials (level 1a). The bulk of literature consists of small descriptive studies (level III) or opinions from respected authorities (level IV). The advent of the NIH-CPSI has provided the opportunity for well-designed trials to be performed where the symptom outcomes can be quantified. This opportunity will be of greatest value in type III prostatitis where symptom amelioration is the main target of therapy and a number of treatment options abound.

Indeno[1,2-b]pyrazin-2,3-diones: a new class of antagonists at the glycine site of the NMDA receptor with potent in vivo activity

Indeno¿1,2-bpyrazin-2,3-diones have been identified as a novel series of potent ligands on the glycine site of the NMDA receptor. To improve their in vivo activities, an acetic acid-type side chain was introduced to the 5-position, giving water-soluble compounds when formulated as the sodium salt (>10 mg/mL). Introduction of a chlorine atom in the 8-position led to a dramatic improvement of anticonvulsant activity and this was surprising since this change did not improve binding affinity. A plausible explanation is a reduced recognition by a Na(+),K(+)-ATPase active transport system responsible for the excretion of these compounds from the brain and kidney. This promising new chemical series led to the optically active isomer (-)-10i (RPR 118723), a glycine/NMDA antagonist with nanomolar binding affinity and in vivo activity in animal model of convulsions and electrophysiology at doses in the range of 2-3 mg/kg following iv administration.

Is the conservative management of ureteric calculi of > 4 mm safe?

OBJECTIVE

To determine the safety of the conservative management of ureteric calculi of > 4 mm in diameter, using mercapto-acetyltriglycine (MAG3) radioisotope renography to monitor renal parenchymal function.

PATIENTS AND METHODS

Patients with symptomatic unilateral ureteric calculi were recruited prospectively. After confirming the position of the stone using contrast urography, a MAG3 radioisotope renogram was taken within 48 h of admission and again 1 month after the patients became stone-free. The indications for intervention were ipsilateral loss of function (>/= 5% loss), infection, pain or any combination of these factors. The recovery of function was determined by follow-up renography.

RESULTS

In all, 54 patients were recruited; 18 were initially allocated to conservative treatment although four later required intervention for pain. The remainder required early intervention for pain (eight), diminished function only (15) or diminished function with infection (13). Of the 54 patients, 28% had 'silent' loss of renal function at presentation. No calculi of > 7 mm diameter passed without intervention. The mode of initial management was determined according to individual clinical need. The upper tracts of all patients were relieved of obstruction and all patients were rendered stone-free. Intervention for reduced function only (at </= 7 days) gave a significantly better (P = 0.03) recovery of function than those undergoing later intervention. The combination of reduced function and infection were unrelated to outcome after intervention.

CONCLUSIONS

The conservative management of stones of 5-7 mm diameter is safe, providing that radioisotope renography is used to identify those renal units requiring intervention. This approach allows timely intervention to maximize the recovery of renal function.

New insights into the mechanism of action of hypnotics

Between 1987 and 1989, the different protein subunits that make up the receptor for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) were identified. These make up the alpha, beta, gamma and delta families, for each of which exist several subtypes. This receptor is the molecular target of modern hypnotic drugs (i.e. benzodiazepines, zopiclone, zolpidem and zaleplon). In the 10 years that have followed this milestone, significant progress has been made in exploring the molecular mechanisms of hypnotic drug action. Receptor subtype specificity of hypnotics has been explained in terms of differential affinity for receptors containing different alpha subunits, which are expressed in different brain regions. Zolpidem and zaleplon bind preferentially to alpha1-containing receptors, whereas benzodiazepines and zopiclone are aspecific. Different sets of subunits are encoded in contiguous 'cassettes' on the genome, and the transcription of each set appears to be regulated coherently. The predominant GABA(A) receptor composition found in the brain is alpha1beta2gamma2, which are all encoded on human chromosome 5. Targeted gene disruption has provided clues to the physiological functions served by GABA(A) receptors containing different subunits. Receptors containing gamma2 appear to have a vital role in maintaining appropriate central inhibition, beta3-containing receptors may also be important determinants of excitability in certain brain regions, whereas a clear role for alpha5-, alpha6- and gamma3-containing receptors has not yet been established by these techniques. Site-directed mutagenesis has indicated that benzodiazepines bind to a cleft on the GABA(A) receptor surface at the interface between the alpha and gamma subunits. Other drugs (flumazenil, zopiclone, zolpidem) also bind to the a subunit, but interact with amino acids in different binding domains to the benzodiazepines. The molecular mechanism of hypnotic dependence has been explored, and seems to involve downregulation of transcription of the normally prevalent alpha1, beta2 and gamma2 subunits, and the reciprocal upregulation of the expression of rarer subunits. Chronic treatment with hypnotic drugs that may have less dependence potential, such as zopiclone and zolpidem, appears to produce more limited change in GABA(A) receptor subunit expression. These ideas will be important both for designing new hypnotic drugs with a better safety/efficacy profile, and for evaluating more appropriate ways of using the drugs available today.

Vesicouterine fistula: MRI diagnosis

A case of vesicouterine fistula in a young woman following caesarean section is presented. The diagnosis was established successfully using heavily T2-weighted MRI which clearly demonstrated fluid within the fistula, obviating the need for conventional radiographic contrast examination.

Immunoassay for urothelial cancers that detects DNA replication protein Mcm5 in urine

Cancer-screening tests for internal organs are severely constrained by low specificity or sensitivity, cost, and morbidity. We report a non-invasive immunofluorometric assay for detection of urothelial cancers based on ectopic expression of the DNA replication protein Mcm5.

Riluzole series. Synthesis and in vivo "antiglutamate" activity of 6-substituted-2-benzothiazolamines and 3-substituted-2-imino-benzothiazolines

Two series of analogues of riluzole, a blocker of excitatory amino acid mediated neurotransmission, have been synthesized: monosubstituted 2-benzothiazolamines and 3-substituted derivatives. Of all the compounds prepared in the first series, only 2-benzothiazolamines bearing alkyl, polyfluoroalkyl, or polyfluoroalkoxy substituents in the 6-position showed potent anticonvulsant activity against administration of glutamic acid in rats. The most active compounds displaying in vivo "antiglutamate" activity were the 6-OCF(3) (riluzole), 6-OCF(2)CF(3), 6-CF(3), and 6-CF(2)CF(3) substituted derivatives with ED(50) values between 2.5 and 3.2 mg/kg i.p. Among the second series of variously substituted benzothiazolines, compounds as active as riluzole or up to 3 times more potent were identified in two series: benzothiazolines bearing a beta-dialkylaminoethyl moiety and compounds with an alkylthioalkyl chain and their corresponding sulfoxides and sulfones. The most potent derivatives were 2-imino-3-(2-methylthio)- and 2-imino-3-(2-methylsulfinyl)-ethyl-6-trifluoromethoxybenzothiazolines (61 and 64, ED(50) = 1.0 and 1.1 mg/kg i.p., respectively). In addition, intraperitoneal administration of some of the best benzothiazolines protected mice from mortality produced by hypobaric hypoxia.

The role of excitotoxicity in neurodegenerative disease: implications for therapy

Glutamic acid is the principal excitatory neurotransmitter in the mammalian central nervous system. Glutamic acid binds to a variety of excitatory amino acid receptors, which are ligand-gated ion channels. It is activation of these receptors that leads to depolarisation and neuronal excitation. In normal synaptic functioning, activation of excitatory amino acid receptors is transitory. However, if, for any reason, receptor activation becomes excessive or prolonged, the target neurones become damaged and eventually die. This process of neuronal death is called excitotoxicity and appears to involve sustained elevations of intracellular calcium levels. Impairment of neuronal energy metabolism may sensitise neurones to excitotoxic cell death. The principle of excitotoxicity has been well-established experimentally, both in in vitro systems and in vivo, following administration of excitatory amino acids into the nervous system. A role for excitotoxicity in the aetiology or progression of several human neurodegenerative diseases has been proposed, which has stimulated much research recently. This has led to the hope that compounds that interfere with glutamatergic neurotransmission may be of clinical benefit in treating such diseases. However, except in the case of a few very rare conditions, direct evidence for a pathogenic role for excitotoxicity in neurological disease is missing. Much attention has been directed at obtaining evidence for a role for excitotoxicity in the neurological sequelae of stroke, and there now seems to be little doubt that such a process is indeed a determining factor in the extent of the lesions observed. Several clinical trials have evaluated the potential of antiglutamate drugs to improve outcome following acute ischaemic stroke, but to date, the results of these have been disappointing. In amyotrophic lateral sclerosis, neurolathyrism, and human immunodeficiency virus dementia complex, several lines of circumstantial evidence suggest that excitotoxicity may contribute to the pathogenic process. An antiglutamate drug, riluzole, recently has been shown to provide some therapeutic benefit in the treatment of amyotrophic lateral sclerosis. Parkinson's disease and Huntington's disease are examples of neurodegenerative diseases where mitochondrial dysfunction may sensitise specific populations of neurones to excitotoxicity from synaptic glutamic acid. The first clinical trials aimed at providing neuroprotection with antiglutamate drugs are currently in progress for these two diseases.

Effects of depolarizing stimuli on calcium homeostasis in cultured rat motoneurones

Intracellular calcium concentrations in individual rat motoneurones in enriched primary cultures were measured by Indo-1 fluorimetry. Motoneurones in the cultures were characterized morphometrically and by cholineacetyltransferase immunocytochemistry. Depolarization of the cells with glutamic acid or veratridine increased intracellular calcium levels, which returned to baseline only slowly after removal of the depolarizing agent. The use of selective agonists (N-methyl-D-aspartic acid, AMPA, kainic acid, quisqualic acid and 1R-3S-ACPD) and antagonists (MK 801 and CNQX) showed that the excitatory amino acid-evoked responses were mediated by AMPA/kainate receptors rather than by NMDA receptors. Depolarization-evoked calcium transients in motoneurones are blocked by the neuroprotective drug riluzole Calcium transients reflected entry of calcium from without the cell, and their blockade by nitrendipine and lanthanum chloride suggested that this entry took place primarily through voltage-dependent calcium channels. These findings may be relevant for understanding the selective vulnerability of motoneurones to excitotoxicity in amyotrophic lateral sclerosis, and the therapeutic activity of riluzole in the treatment of this disease.

Interaction of brain cannabinoid receptors with guanine nucleotide binding protein: a radioligand binding study

The binding of a classical cannabinoid agonist, [3H]R-(+)-(2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrol[1,2 ,3-de]-1,4-benzoxazin-6-yl)(1-napthalenyl)methanone monomethanesulfonate ([3H] WIN55212-2), and a selective cannabinoid receptor (CB1) antagonist, N-(piperidin-1-yl)-5-(4-chlorophenyl)1-(2,4-dichlorophenyl)-4-meth yl-1H-pyrazole-3-carboxamide hydrochloride ([3H]SR141716A), to rat cannabinoid receptors was evaluated using rat cerebellar membranes. Guanine nucleotides inhibited [3H]WIN55212-2 binding by approximately 50% at 10 microM and enhanced [3H]SR141716A binding very slightly. In the same tissue, the binding of guanosine 5'-O-[gamma-[35S]thio]triphosphate ([35S]GTP-gamma-S) was characterized and the influence of cannabinomimetics evaluated on this binding. Cannabinoid receptor agonists enhanced [35S]GTP-gamma-S binding, whereas SR141716A was devoid of action by itself but antagonized the action of cannabinoid receptor agonists. The good correlation obtained between the half maximum efficient concentration (EC50) values in [35S]GTP-gamma-S binding and the IC50 values [3H]WIN55212-2 binding shows that [35S]GTP-gamma-S binding could be a good functional assay for brain cannabinoid receptors.

Therapeutic advances in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive and rapidly fatal neurodegenerative disease in which both upper and lower motoneurones are involved. The recent discovery of mutations affecting the superoxide dismutase (SOD) gene has given impetus to research on the role of oxidative stress in the pathogenesis of familial ALS, while further evidence for a role of excitotoxicity in the disease process has arisen. In this review, Erik Louvel, Jacques Hugon and Adam Doble discuss these findings and, in addition, describe how a number of large, well-controlled clinical trials have taken place to test potential therapies suggested by different aetiological hypotheses, including immunosuppressive therapies, neurotrophic factors, antioxidants and anti-excitotoxic drugs. These trials have led to the first modest steps in the treatment of this devastating neurological disease.

The pharmacology and mechanism of action of riluzole

The excitotoxic hypothesis of neurodegeneration has stimulated much interest in the possibility of using compounds that will block excitotoxic processes to treat neurologic disorders. Riluzole is a neuroprotective drug that blocks glutamatergic neurotransmission in the CNS. Riluzole inhibits the release of glutamic acid from cultured neurons, from brain slices, and from corticostriatal neurons in vivo. It is thought these effects may be partly due to inactivation of voltage-dependent sodium channels on glutamatergic nerve terminals, as well as activation of a G-protein-dependent signal transduction process. Riluzole also blocks some of the postsynaptic effects of glutamic acid by noncompetitive blockade of N-methyl-D-aspartate (NMDA) receptors. In vivo, riluzole has neuroprotective, anticonvulsant, and sedative properties. In a rodent model of transient global cerebral ischemia, a complete suppression of the ischemia-evoked surge in glutamic acid release has been observed. In vitro, riluzole protects cultured neurons from anoxic damage, from the toxic effects of glutamic-acid-uptake inhibitors, and from the toxic factor in the CSF of patients with amyotrophic lateral sclerosis.

Localization of presenilin-1 mRNA in rat brain

We examined the regional and cellular distribution of presenilin-1 gene expression in the rat brain by in situ hybridization. Microscopic analysis demonstrated that presenilin-1 mRNA is predominantly expressed in areas such as the occipital cortex, the pyramidal layer of the hippocampus, thalamic nuclei and the cerebellar granular layer. The expression of presenilin-1 is mostly neuronal: only a weak hybridization signal was found in the corpus callosum and in the astrocytoma cell lines U373MG and U138MG.

The naphtosultam derivative RP 62203 (fananserin) has high affinity for the dopamine D4 receptor

The dopamine D4 receptor is a potential target for novel antipsychotic drugs. Most available compounds with affinity for the dopamine D4 receptor also bind to dopamine D2 receptors. This report describe the affinity of the 5-HT2A receptor antagonist RP 62203 (fananserin) for the human dopamine D4 receptor. Fananserin displaces [3H]spiperone binding to recombinant human dopamine D4 receptors with a Ki of 2.93 nM. This compares with an affinity (Ki) of 0.37 nM for the rat 5-HT2A receptor and of 726 mM for the rat dopamine D2 receptor. [3H]Fananserin can be used to label the recombinant dopamine D4 receptor expressed in Chinese hamster ovary cells with a KD of 0.725 nM. Fananserin is, thus, the first compound to be reported that distinguishes between dopamine D4 and D2 receptors.

A review of antegrade stenting in the management of the obstructed kidney

OBJECTIVE

To review experience in the management of the obstructed ureter using antegrade stenting in a variety of conditions.

PATIENTS AND METHODS

Between 1984 and 1993, 41 patients (mean age 57 years, range 9-83) had antegrade stents placed by an experienced interventional radiologist. The causes of obstruction were urological in 27, gynaecological in eight, colorectal in three and miscellaneous in three.

RESULTS

The overall success rate for antegrade stent insertion was 83% and the failure rate was greatest (four of six) in cases of ureteric injury following gynaecological procedures. There were no immediate complications.

CONCLUSION

Antegrade stenting can be used as a temporary or permanent solution to ureteric obstruction. The technique is safe, acceptable to patients and avoids the need for a general anaesthetic.

Neuroprotective effects of riluzole on a model of Parkinson's disease in the rat

The aim of the present study was to analyse whether riluzole, a compound that interacts with the voltage-dependent sodium channel and impairs glutamatergic transmission, would exhibit a neuroprotective activity in a model of Parkinson's disease in the rat. Impaired skilled forelimb use, circling behavior, and altered dopaminergic metabolism of the mesotelencephalic system were evaluated in unilaterally 6-hydroxydopamine-lesioned rats. Riluzole was administered twice 15 min before, and 24 h after, the lesion. Riluzole reduced both the contralateral rotations induced by apomorphine and the ipsilateral ones elicited by amphetamine. Moreover, the decreased dopaminergic metabolism seen after 6-hydroxydopamine injection was attenuated in the riluzole-treated animals, at both the striatal and nigral levels. These biochemical and behavioral results demonstrate the ability of riluzole partially to protect the degeneration of the nigrostriatal dopaminergic neurons induced by the toxin 6-hydroxydopamine. Perhaps, the most striking evidence for the protective effect of riluzole was that this compound improved the skilled paw use, a complex sensorimotor behavior which is not easily ameliorated by palliative therapies such as dopaminergic grafts. These results extend previous data showing that riluzole counteracts the toxicity induced by 1-methyl-4-1,2,3,6-tetrahydropyridine and 1-methyl-4-phenylpyridinium in rodent dopaminergic neurons. The use of riluzole may be considered of potential interest for the neuroprotective therapy of Parkinson's disease.

Molecular cloning, functional expression, pharmacological characterization and chromosomal localization of the human metabotropic glutamate receptor type 3

Glutamic acid is the major excitatory amino acid of the central nervous system which interacts with two receptor families, the ionotropic and metabotropic glutamate receptors. The metabotropic glutamate receptors (mGluRs) are coupled to G proteins and can be divided into three subgroups based on their sequence homology, signal transduction pathway and pharmacology. In this study, we describe the cloning of the cDNA encoding the human metabotropic glutamate receptor type 3 (HmGluR3). It was obtained by reverse transcription-polymerase chain reaction (RT-PCR) with degenerate oligonucleotides corresponding to highly conserved sequences between rat mGluRs. The receptor shows 879 amino acids with 96% amino acid sequence identity with rat mGluR3. It is strongly expressed in fetal and adult whole brain, especially in caudate nucleus and corpus callosum. The gene was identified by fluorescence in situ hybridization on chromosome 7 band q22. Activation of the human mGluR3, permanently expressed in Baby Hamster Kidney (BHK) cells, by excitatory amino acid inhibits the forskolin-stimulated accumulation of intracellular cAMP. The rank order of potency is L-glutamic acid > or = (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R)-ACPD) >> ibotenic acid > quisqualic acid. (RS)-alpha-methyl-4-carboxyphenylglycine [(RS)-MCPG, 1 mM] is without effect on inhibition of forskolin-induced cAMP accumulation by L-glutamic acid.

Neuroprotective effects of RPR 104632, a novel antagonist at the glycine site of the NMDA receptor, in vitro

The NMDA antagonist and neuroprotective effects of RPR 104632 (2H-1,2,4-benzothiadiazine-1-dioxide-3-carboxylic acid), a new benzothiadiazine derivative, with affinity for the glycine site of the NMDA receptor-channel complex are described. RPR 104632 antagonized the binding of [3H]5,7-dichlorokynurenic acid to the rat cerebral cortex, with a Ki of 4.9 nM. This effect was stereospecific, since the (-)-isomer was 500-fold more potent than the (+)-isomer. The potent affinity of RPR 104632 for the glycine site was confirmed by the observation that RPR 104632 inhibited [3H]N-[1-(2-thienyl)cyclohexyl]-3,4-piperidine ([3H]TCP) binding in the presence of N-methyl-D-aspartate (NMDA) (IC50 = 55 nM), whereas it had no effect on the competitive NMDA site or on the dissociative anaesthetic site. RPR 104632 inhibited the NMDA-evoked increase in guanosine 3',5'-cyclic monophosphate (cGMP) levels of neonatal rat cerebellar slices (IC50 = 890 nM) in a non-competitive manner and markedly reduced NMDA-induced neurotoxicity in rat hippocampal slices and in cortical primary cell cultures. These results suggest that RPR 104632 is a high-affinity specific antagonist of the glycine site coupled to the NMDA receptor channel with potent neuroprotective properties in vitro.

Biochemical and pharmacological characterization of cannabinoid binding sites using [3H]SR141716A

This study describes the binding characteristics of cannabinoid binding sites expressed in rat cerebellar membranes using the tritiated derivative of SR141716A, the newly described cannabinoid receptor antagonist. A single population of high-affinity binding sites (K(D) = 0.59 +/- 0.08 nM; Bmax = 3.86 +/- 0.42 pmol mg-1 of protein) was demonstrated. Kinetic, competition and saturation experiments give similar results in terms of SR141716A affinity. delta 9-tetrahydrocannabinol and the 11-hydroxy derivative competitively inhibited the specific binding of [3H]SR141716A (Ki = 47 +/- 9 and 32 +/- 4 nM, respectively). The cannabinoid agonist WIN55212-2 has a 25-fold lower affinity for [3H]SR141716A than for [3H]WIN55212-2, showing that the two ligands do not recognize the cannabinoid binding site in the same fashion.

Benefit of vitamin E, riluzole, and gabapentin in a transgenic model of familial amyotrophic lateral sclerosis

Familial amyotrophic lateral sclerosis (FALS) has been linked in some families to dominant mutations of the SOD1 gene encoding Cu,Zn superoxide dismutase (Cu,ZnSOD). We have used a transgenic model of FALS based on expression of mutant human Cu,ZnSOD to explore the etiology and therapy of the genetic disease. Expression of mutant, but not wild-type, human Cu,ZnSOD in mice places the brain and spinal cord under oxidative stress. This causes depletion of vitamin E, rather than the typical age-dependent increase in vitamin E content as occurs in nontransgenic mice and in mice expressing wild-type human Cu,ZnSOD. Dietary supplementation with vitamin E delays onset of clinical disease and slows progression in the transgenic model but does not prolong survival. In contrast, two putative inhibitors of the glutamatergic system, riluzole and gabapentin, prolong survival. However, riluzole did not delay disease onset. Thus, there was clear separation of effects on onset, progression, and survival by the three therapeutics tested. This suggests the hypothesis that oxidative damage produced by the expression of mutant Cu,ZnSOD causes slow or weak excitotoxicity that can be inhibited in part by alerting glutamate release or biosynthesis presynaptically.

3-Nitropropionic acid exacerbates [3H]GABA release evoked by glucose deprivation in rat striatal slices

3-Nitropropionic acid (3-NPA) is a metabolic poison that produces lesions of striatal intrinsic neurones such as gamma-aminobutyric acid (GABA) neurones. This study was carried out to determine whether 3-NPA would impair the ability of striatal GABAergic neurones to withstand hypoglycaemic stress. 3-NPA (500 microM) did not affect [3H]GABA release from striatal slices under normal (11 mM) glucose concentrations. When the glucose concentration was lowered to 0.3 mM, however, 3-NPA greatly potentiated the leakage of [3H]GABA from the slices. Blockage of N-methyl-D-aspartate (NMDA) or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors with 1 microM 5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801) or 10 microM 2,3-dihydroxy-6-nitro-7-sulpha-moylbenzo[F]quinoxaline (NBQX), respectively, or a combination of both, had no effect. However, blockade of voltage-dependent sodium channels with tetrodotoxin totally antagonized the [3H]GABA overflow induced by the combination of 3-NPA and hypoglycaemis. Riluzole (10 to 100 microM), a neuroprotective agent that stabilizes the inactivated state of the voltage-dependent sodium channel, also dose-dependently antagonized the increase in [3H]GABA release induced by the combination of the two stresses.

The antidepressant metapramine is a low-affinity antagonist at N-methyl-D-aspartic acid receptors

Metapramine, a pharmacological compound with antidepressant activity in humans, was tested for possible antiglutamatergic activity, in vitro. We investigated the effects of metapramine on the N-methyl-D-aspartic acid (NMDA) receptor complex, by determining whether this compound would interfere with the binding of [3H]N-[1-(2-thienyl)cyclohexyl]-3,4-piperidine ([3H]TCP) to rat cortical membranes in the presence of either glycine NMDA, or both. Metapramine in the micromolar range inhibited the binding of [3H]TCP in the presence of both NMDA and glycine (IC50 = 1.4 +/- 0.2 microM). That very similar affinities were observed when either NMDA or glycine was present suggests that metapramine exerted a direct action at the PCP site. The affinity of metapramine for this site was about 25 and 350 times lower than that of PCP and MK-801, respectively. Metapramine inhibited the NMDA-evoked increase in guanosine 3',5'-cyclic monophosphate (cGMP) levels of neonatal rat cerebellar slices (IC50 = 13 microM). These results suggest that metapramine is a low-affinity antagonist of the NMDA receptor complex channel. This paper discusses the potential application of metapramine to the treatment of diseases linked to excessive stimulation of glutamatergic NMDA receptors.

Effects of AMPA receptor modulators on the production of arachidonic acid from striatal neurons

The abilities of different compounds acting at alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors to modulate the overflow of [3H]arachidonic acid from rat striatal neurons were examined. The combination of AMPA (0.1 mM) and carbachol (1mM) stimulated [3H]arachidonic acid production, this effect could be dose-dependently enhanced by the newly discovered allosteric modulator of AMPA receptors: cyclothiazide. Competitive (6-cyano-7-nitroquinoxaline-2,3-dione [CNQX] and 6-(1-imidazolyl)-7-nitroquinazoline-2,3-dione [YM 900]) and non-competitive antagonists, like 1-(amino)-phenyl)-4-methyl -7,8-methylenedioxy-5H-2,3-benzodiazepine (GYKI 52466), antagonized the responses induced by either AMPA + carbachol or AMPA + carbachol + cyclothiazide. In order to appreciate the respective part of AMPA-versus kainate-preferring receptors experiments were performed with kainic acid (0.1 mM) and the more specific kainate agonist domoic acid (0.1 mM). Kainic acid behaves like AMPA, but the response induced by the combination domoic acid + carbachol could not be potentiated by cyclothiazide. On the contrary, concanavalin A potentiated the responses evoked by kainic acid or domoic acid (in combination with carbachol) but did not enhance the AMPA-evoked response. It could be concluded that both AMPA- and kainate-preferring receptors are present in cultured rat striatal neurons and that these two types of receptors were involved together with muscarinic receptors in the overflow of [3H]arachidonic acid.

Methamphetamine and dopamine neurotoxicity: differential effects of agents interfering with glutamatergic transmission

The effects of riluzole and lamotrigine, two agents which interfere with the release of glutamate (GLU), and MK-801, a blocker of N-methyl-D-aspartate (NMDA) receptors, were compared in the model of methamphetamine-induced depletion of dopamine (DA) levels in mice. Repeated injections with methamphetamine (4 x 5 mg/kg i.p.) markedly decreased levels of DA, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels. When mice were treated with riluzole (2 x 10 mg/kg p.o.), no protection was observed against the decrease in DA and the two metabolites. Lamotrigine (2 x 10 mg/kg p.o.) was also inactive. Treatment with MK-801 (2 x 2.5 mg/kg i.p.) antagonized the decrease in DA, DOPAC and HVA levels induced by the neurotoxin. Thus, unlike an NMDA blocker, drugs that interfere with GLU release did not antagonize the methamphetamine-induced DA neurotoxicity in mice. The consequences of this inactivity are discussed in terms of the reliability of this model to test new drugs with putative efficacy in the treatment of Parkinson's disease.

Excitatory amino acid receptors and neurodegeneration

This review describes recent advances in our understanding of the pharmacology of excitatory amino acid receptors, and the application of this knowledge to the unravelling of the aetiology of neurodegenerative diseases, and to their therapy. Ionotropic excitatory amino acid receptors can be divided into two large families, the NMDA receptor family, and the AMPA/kainate receptor family. Receptor cloning studies have shown there to be a large number of potential subtypes of receptors in both these families. Antagonists have been developed for the NMDA receptor which can interact with at least four independent drug recognition sites on the receptor. For the AMPA/kainate receptor, two classes of antagonist have so far been identified. Reasonably potent, selective and brain-penetrating antagonists now exist for virtually all these sites, and compounds inhibiting the release of glutamic acid presynaptically have also been identified, such as riluzole. The ability of glutamic acid to kill neurons (excitotoxicity) seems to be mediated, in most cases, by an interaction with NMDA receptors, leading to an uncontrollable rise in intracellular calcium concentrations and thence cell lysis and death. The setting-up of glutamatergic loops seems to be a key process in the maintenance, spread and amplification of neurodegenerative foci. The existence of such processes has been amply demonstrated in animal models of stroke, in which both NMDA and AMPA/kainate receptor antagonists have neuroprotective effects. Clinical trials are underway with NMDA receptor antagonists in stroke. Excitotoxic mechanisms probably also contribute to pathology in head trauma and viral encephalopathy. Ingestion of excitatory amino acids may play a role in neurological conditions of dietary aetiology, such as neurolathyrism and domoic acid intoxication. For chronic neurodegenerative diseases, the role of excitatory amino acids is much less clear, although there is some evidence for the existence of excitotoxic mechanisms in amyotrophic lateral sclerosis. Evidence from animal models suggests that drugs that block glutamatergic neurotransmission might be beneficial in Parkinson's disease, Huntington's chorea and amyotrophic lateral sclerosis, but the relevance of these animal models to the human pathology is not clear. However, preliminary clinical results suggest riluzole to be efficacious in prolonging survival in amyotrophic lateral sclerosis, and certain weak NMDA receptor antagonists are currently used in the treatment of Parkinson's disease. The next few years could witness a breakthrough in the treatment of neurological conditions as drugs that interfere with glutamatergic transmission become available for clinical use.

Effects of non-NMDA receptor modulators on [3H] dopamine release from rat mesencephalic cells in primary culture

The effects of AMPA and kainate on [3H]dopamine release from fetal (embryonic day 15) rat mesencephalic neurons in primary culture were enhanced markedly in a dose-dependent fashion by cyclothiazide, a recently described inhibitor of AMPA receptor desensitization. The EC50 value for cyclothiazide was 2.2 +/- 0.8 microM. The release of [3H]dopamine induced by both AMPA (or kainic acid) and the combination of AMPA (or kainic acid) with cyclothiazide was antagonized by specific antagonists like 6-cyano-7-nitroquinoxaline-2,3-dione or the noncompetitive benzodiazepine GYKI 52466. Unlike cyclothiazide, the lectin concanavalin A did not stimulate [3H]dopamine release. These results established the involvement of AMPA-preferring receptors on [3H]dopamine release from rat mesencephalic neurons in primary culture and provided further evidence for the existence of regulatory allosteric sites on AMPA receptor subunits.

Riluzole and experimental parkinsonism: antagonism of MPTP-induced decrease in central dopamine levels in mice

We have investigated whether riluzole, a compound that interferes with glutamatergic (GLUergic) transmission, would protect central dopaminergic (DAergic) neurones from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced toxicity in the striatum in mice. MPTP decreased DA, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels. Riluzole protected against the MPTP-induced decrease in DA levels. The utilization of DA ([DOPAC+HVA]/DA) was increased after MPTP treatment, but returned to control values in mice given riluzole in combination with MPTP. Riluzole did not confer protection by inhibiting either monoamine oxidase type B activity or DA uptake. Possible mechanisms involved in the protective action of riluzole are discussed. Our results show that riluzole antagonizes the DAergic neurotoxicity of MPTP, a pro-parkinsonian neurotoxin, in mice.

Congo red protects against toxicity of beta-amyloid peptides on rat hippocampal neurones

beta-Amyloid peptides are neurotoxic when applied to primary cultures of hippocampal neurones from the embryonic rat. This neurotoxic effect can be inhibited completely by certain disazo dyestuffs. The most potent of these are Congo Red and Congo Rubin, whilst Direct Garnet and sodium 4-aminonaphthalene-1-sulphonate are inactive. Congo Red also inhibits the neurotoxic effects of the human pancreatic amyloidogenic peptide amylin. It is postulated that these dyes, by interacting with the beta-pleated sheet structure of amyloidogenic peptides, prevent aggregation and hence neurotoxity.