A Phase I/II Dose-Escalation Study Evaluating the Safety of 21 Gy, 23 Gy, and 25 Gy for High Dose Rate (HDR) Prostate Brachytherapy: An Interim Toxicity Report

PURPOSE/OBJECTIVE(S)

Single-fraction high dose rate (HDR) prostate brachytherapy has shown improved actuarial biochemical control rates from 66% to 82% with dose escalation from 19 to 20.5 Gy, respectively, but is still inferior to the reported low dose rate brachytherapy control rates of over 90%. We aimed to identify whether dose escalation to 21, 23, and 25 Gy can be safely accomplished.

MATERIALS/METHODS

Patients with previously untreated, pathologically confirmed, low-risk (cT1-T2a, Gleason ≤6, PSA <10 ng/mL) or favorable intermediate risk (Gleason 3+4, percentage of positive biopsy cores <50%, ≤1 NCCN intermediate risk factor) prostate adenocarcinoma were enrolled from a single institution. PSA and toxicity assessment were performed at baseline and at routine 6-month follow-ups.

RESULTS

From May 9, 2018 to May 12, 2022, 18 patients were enrolled. None had received prior androgen deprivation therapy, 44% had low risk disease, and 61% were ECOG 0 at baseline. Median age was 68 years (total range: 43-79), and 83% were Caucasian. Eight patients received 21 Gy, nine patients received 23 Gy, and one patient received 25 Gy, with the 25 Gy cohort still accruing. The mean prostate size and range, determined by pre-operative prostate volume study on trans-rectal ultrasound, were as follows: 21Gy cohort (mean: 41.2cc; range: 21.9-63.1cc), 23Gy Cohort (mean: 41.2cc, range 28.3-71.7cc), 25Gy cohort (65.3cc). A median of 17 catheters (range: 16-20) were implanted. At a median follow-up of 35.7 months (range: IQR 4.4 - 50.2), only one grade 3 toxicity was reported, which was an ulcerative colitis (UC) flare noted in a patient whose UC was poorly controlled, requiring multiple courses of prednisone in the 6 months prior to his brachytherapy. Regarding toxicities attributable to therapy, fourteen and four patients experienced a grade 1 and 2 genitourinary toxicity respectively; four and four patients experienced a grade 1 and 2 reproductive system toxicity respectively; one patient experienced a grade 1 GI toxicity. Two patients needed foley catheters upon discharge, with neither requiring the foley long term. There were two treatment failures in the 21Gy cohort at 1.39 and 1.67 years from date of HDR brachytherapy; date of failure was defined by the first PSA 2.0ng/mL over nadir. Of these patients, one underwent focal salvage HDR, whilst the other underwent radical prostatectomy with only 1% of the volume involved by prostate cancer. Of note, there was seminal vesicle involvement on restaging prostate biopsy for the patient that underwent radical prostatectomy, however, this was not appreciated on the final prostatectomy specimen. Both patients have no evidence of disease currently.

CONCLUSION

HDR brachytherapy appears well tolerated in patients with low to favorable intermediate risk prostate cancer at 21 and 23 Gy, with more accrual needed at 25Gy. Long-term follow-up needed to assess efficacy.

Association of Managed Medicaid Plans and Cancer Stage at Diagnosis

PURPOSE/OBJECTIVE(S)

Managed care organizations provide insurance to many Medicare (Advantage) and Medicaid beneficiaries and seek to maintain quality while controlling provider networks, utilization, and costs. In prior research, patients with Medicare Advantage plans had restricted access to care, including at cancer centers, and had higher mortality after cancer surgery than patients with traditional Medicare. Over 80% of Medicaid patients nationally are enrolled in managed care plans; despite their prevalence, there is a paucity of evidence regarding the quality of cancer care provided by these plans. We examined associations of state-level managed Medicaid rates and cancer stage at diagnosis.

MATERIALS/METHODS

Adults ages 18-64 years with Medicaid coverage diagnosed with cancer from 2007-2016 were identified from Surveillance, Epidemiology, and End Results program data covering 12 states. Note that 2016 was the last year with unsuppressed insurance status data. Year-varying state-level rates of types of managed Medicaid plans (comprehensive risk-based managed care, limited benefit plans, and primary care case management) were obtained from the Medicaid and CHIP Payment and Access Commission and categorized in quartiles. The association of state levels of each type of managed Medicaid plan with localized stage diagnoses was evaluated using multivariable linear probability models with cluster-robust standard errors (state clusters) accounting for state fixed effects, year fixed effects, age, sex, race, metropolitan residence, marital status, county-level income and education, state Medicaid expansion status, and cancer type.

RESULTS

A total of 229,227 Medicaid patients were identified. The average state-level rates of comprehensive managed care, limited benefit, and primary care case management plans were 47%, 47%, and 5.6%, respectively. In adjusted analyses, relative to states with <20% of Medicaid recipients enrolled in comprehensive managed care plans, states with 40-80% (-2.07 percentage points, 95% CI = -3.31 to -0.83, P = .001) and >80% (-1.49, 95% CI = -2.49 to -0.50, P = .003) had fewer localized stage diagnoses. States with >2% relative to 0-1% of recipients enrolled in primary care case management plans had more localized stage diagnoses (1.02, 95% CI = 0.27 to 1.77, P = .008). States with higher levels of limited benefit plans had more localized stage diagnoses (P = .011), though associations were attenuated with increasing levels (20-40%: 1.22; 40-80%: 0.53; >80%: 0.40). Patterns were similar across most cancer types.

CONCLUSION

The prevalence and type of Medicaid managed care plans are associated with early-stage cancer diagnoses. Higher levels of comprehensive managed care plans were associated with fewer early diagnoses, raising concerns about barriers to symptom evaluation and diagnostic workup. In contrast, higher levels of primary care case management plans were associated with more early diagnoses, potentially through streamlined care coordination.

Disparities in Inpatient Care Including Receipt of Radiotherapy and Mortality in Unhoused Adults with Cancer in the United States

PURPOSE/OBJECTIVE(S)

Cancer is the second leading cause of death among unhoused individuals in the United States. This study aims to assess inpatient care and outcomes of unhoused vs. housed adults with cancer. We hypothesize that unhoused patients receive less intensive care than housed patients during hospitalization.

MATERIALS/METHODS

All hospitalized adults age ≥18 with a principal cancer diagnosis were identified in the 2016-2020 National Inpatient Sample (NIS). Logistic regression models tested for associations between housing status and primary outcomes: care management (i.e., receipt of invasive procedures, systemic therapy, or radiation therapy [RT]) and inpatient death. Adjusted analyses accounted for patient demographics, socioeconomic status, comorbidities, and potential interactions between housing status and length of stay (LOS).

RESULTS

A total of 9,030 unhoused and 2,758,693 housed hospitalized adults with cancer were included in this study. At baseline, there were significant (p<0.05) differences in age <65 years (77% unhoused vs. 41% housed), male sex (75% vs. 53%), race (Black, 25% vs. 13%; White, 58% vs. 71%), and insurance type (Private, 6% vs. 27%; Medicaid, 53% vs. 11%) between groups. There were also differences in the prevalence of certain cancer histologies, including lung (17% vs. 14%) and liver (8% vs. 3%) cancer. Additionally, while comorbidities such as congestive heart failure (18% vs. 15%) and HIV (10% vs. 1%) were more common among unhoused patients, other conditions such as autoimmune disease (21% vs. 26%) and diabetes mellitus (38% vs. 43%) were more common among housed patients. Compared to housed patients, unhoused patients had longer LOS (median 6 vs. 4 days), with 62% hospitalized for ≥5 days (vs. 46%). On adjusted analysis, unhoused patients were less likely to undergo invasive procedures (48% vs. 58%; aOR [95% CI], 0.34 [0.27-0.42]) or receive systemic therapy (6% vs. 8%; 0.41 [0.20-0.85]) while inpatient. There were no significant differences in odds of receipt of RT (2% vs. 1%; 0.85 [0.21-3.41]) or odds of inpatient death (4% vs. 6%; 0.78 [0.52-1.15]) between groups.

CONCLUSION

In this first nationally representative analysis of housing status among hospitalized adults with cancer, unhoused adults were significantly less likely to receive invasive procedures or systemic therapy while inpatient, despite a higher prevalence of certain aggressive cancers and serious comorbidities compared to housed adults. Although there were no significant differences in the receipt of RT or death, disparities in inpatient management among unhoused patients highlight missed opportunities to promote equitable cancer care in this vulnerable population.

State Mandatory Paid Family Leave and Survival among Children with Cancer

PURPOSE/OBJECTIVE(S)

Childhood cancer treatment is often costly and time intensive and may require parents/caregivers to stop working. Since 2012, several states have introduced mandatory paid family leave policies. We hypothesized that such policies, whether by reducing financial toxicity or by providing parents greater flexibility to care for their sick children, would improve outcomes among children with cancer.

MATERIALS/METHODS

Children ages 0-18 years diagnosed with cancer between 2010 and 2019 were identified from the Surveillance, Epidemiology, and End Results program (SEER) database. The primary outcome was overall survival (OS). The exposure of interest was state mandatory paid family leave. Difference-in-differences (DID) analyses with additive hazards regression models were utilized to compare changes in OS from pre- to post- mandatory paid sick leave policy implementation in states with vs. without paid sick leave policies. The models were adjusted for year fixed effects, state fixed effects, state Medicaid expansion status, age, race, sex, metropolitan residence status, county-level income and education, cancer site, cancer stage, and insurance status. Clustered standard errors by state were achieved via the cluster bootstrap. The plausibility of the common trends assumption was tested using event study analyses and was satisfied for all analyses.

RESULTS

A total of 38,053 children with cancer were identified. In adjusted difference-in-differences analyses, there was no significant change in OS in states with vs. without state mandatory paid family leave policies after policy enactment (hazard difference: 0.0001, 95% CI = -0.0002 to 0.0016, P = .47). However, among non-metropolitan residents, 1-year OS improved from 93.0% to 95.5% (2-year OS: 88.6% to 93.4%) in states with mandatory paid family leave policies compared to 92.7% to 92.5% (2-year OS: 88.0% to 87.7%) in states without such policies after policy enactment. This translates to a 2.7% improvement in 1-year OS (5.2%, 2-year OS) (hazard difference: -0.0021, 95% CI = -0.0034 to -0.0005, P = .037). There was no corresponding change for metropolitan residents (hazard DID = 0.0001, P = .47). By cancer site, the largest policy-associated improvements in survival were observed for rhabdomyosarcoma (hazard DID = -0.0037, P = .11), osteosarcoma (hazard DID = -0.0036, P<.001), and Intracranial and intraspinal embryonal tumors (hazard DID = -0.0026, P = .061).

CONCLUSION

State mandatory paid family leave policies were associated with improved survival for some children with cancer, most notably for those residing in non-metropolitan areas. The improvements for non-metropolitan residents may be related to alleviating otherwise increased travel burdens for cancer treatment if treatment occurs out-of-town, where working while taking care of a child is less feasible. These data also suggest a slight narrowing in rural-urban-metropolitan childhood cancer disparities associated with paid family leave policies.

Characterisation of mobile colistin resistance genes (mcr-3 and mcr-5) in river and storm water in regions of the Western Cape of South Africa

Background

Colistin is regarded as a last-resort antimicrobial against multi-drug resistant Gram-negative bacteria (GNB), therefore the dissemination of colistin resistance in the environment is of great concern. Horizontal transfer of mobile colistin resistance (mcr) genes to potential pathogens poses a serious problem. This study aimed to describe the presence of colistin resistant GNB and mcr genes in river and storm water in regions of the Western Cape.

Methods

Water samples were collected from three rivers during May 2019 and January 2020 and two storm water samples were collected in November 2019. Colistin resistant GNB were cultured on MacConkey agar containing colistin and identified by MALDI-TOF. Colistin resistance was confirmed using broth microdilution (BMD). mcr-1-5 genes were detected by PCR performed directly on the water samples and on the colistin resistant isolates. mcr functionality was assessed by BMD after cloning the mcr genes into pET-48b(+) and expression in SHuffle T7 E. coli.

Results

mcr-5.1 and various mcr-3 gene variants were detected in the Plankenburg-, Eerste- and Berg rivers and in storm water from Muizenberg, and only mcr-5.1 was detected in storm water from Fish Hoek. Colistin resistant GNB were isolated from all of the water sources. Aeromonas spp. were the most common colistin resistant organisms detected in the water sources; 25% (6/24) of colistin resistant Aeromonas spp. isolated from the Berg river contained novel mcr-3 variants; mcr-3.33 (n = 1), mcr-3.34 (n = 1) mcr-3.35 (n = 1) mcr-3.36 (n = 2) and mcr-3.37 (n = 1), which were confirmed to confer colistin resistance.

Conclusions

The mcr-5.1 and mcr-3 colistin resistance gene variants were present in widely dispersed water sources in regions of the Western Cape. The mcr genes were only detected in water sampled downstream of and alongside communities, suggesting that their presence is driven by human influence/contamination. This is the first documentation of mcr-3 and mcr-5 gene variants in any setting in South Africa. Spill-over of these genes to communities could result in horizontal gene transfer to pathogenic bacteria, exacerbating the challenge of controlling multidrug resistant GNB infections.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00963-2.

Early childhood caries and dental treatment need in low socio-economic communities in Cape Town, South Africa

Background

Early childhood caries (ECC) is a particularly severe problem in low socio-economic communities which impacts the overall health and well-being of children. The extensive waiting lists for general anaesthesia and sedation services at the only tertiary dental care centre in the study area for the treatment of children with ECC were an indication of the extent of the problem. The true extent of the problem in this area was, however, not known. This information is crucial in order to plan and execute remedial measures.

Aim

To assess the prevalence of oral and dental problems, especially ECC, in children under six years of age in the study population, and ascertain their need for dental treatment.

Methods

A cross-sectional survey of 659 children from selected schools and clinics in the study area was carried out between 2010 and 2013.

Results

A caries prevalence of 71.6% (472/659) was recorded. Of these, 67.5% (445/659) of children were in need of dental treatment.

Conclusion

Over the last decade, there has been no improvement in the caries status of children in the study population, and no organised measures have been put in place to address this problem. Awareness needs to be raised so that governments, especially in developing countries, can take appropriate measures to alleviate this public health problem. Time and resources have to be invested in the education of all health professionals dealing with children, by raising their awareness of the early stages of the disease so that timeous referrals can be made.

Capture-recapture to estimate completeness of tuberculosis surveillance in two communities in South Africa

BACKGROUND

Reliable surveillance is essential for any tuberculosis (TB) control programme; however, under-registration of TB cases due to under-notification of patients on treatment or failure to initiate treatment has been well-documented internationally.

OBJECTIVE

To determine the contribution of capture-recapture methods in estimating the completeness of bacteriologically confirmed pulmonary TB registration in two high-incident communities in South Africa.

METHODS

Record linkage between the TB treatment register and two laboratory sputum TB result registers and three-source log-linear capture-recapture analysis.

RESULTS

The number of bacteriologically confirmed pulmonary TB cases in the TB treatment register was 243, with an additional 63 cases identified in the two laboratory databases, resulting in 306 TB cases. The observed completeness of the TB treatment register was 79%. The log-linear model estimated 326 (95%CI 314-355) TB cases, resulting in an estimated completeness of registration of 75% (95%CI 68-77).

CONCLUSION

Capture-recapture can be useful in evaluating the completeness of TB control surveillance and registration, including in resource-limited settings; however, methodology and results should be carefully assessed. Interventions are needed to increase the completeness of registration and to reduce the number of initial defaulters.

Contribution of water pollution from inadequate sanitation and housing quality to diarrheal disease in low-cost housing settlements of Cape Town, South Africa

OBJECTIVES

We investigated the effects of failing sanitation, poor housing conditions, and fecal pollution in runoff water on the health-particularly the incidence of diarrheal disease-of residents of low-cost housing settlements in Cape Town, South Africa.

METHODS

In November 2009, we conducted a cross-sectional survey with structured interviews in 4 communities (n = 336 dwellings; 1080 persons). We used Colilert defined-substrate technology to determine Escherichia coli levels in runoff water samples taken from the study communities.

RESULTS

Almost 15% of households disposed of soiled products in storm water drains and 6% disposed of soiled products in the street. In only 26% of the dwellings were toilets washed daily. Approximately 59% of dwellings lacked a tap near the toilet for hand washing, and 14% of respondents suffered 1 or more attacks of diarrhea in the 2 weeks preceding their interview. E.coli counts of runoff environmental water samples ranged from 750 to 1 580 000 000 per 100 milliliters.

CONCLUSIONS

A holistic and integrated approach is needed to improve housing quality and sanitation among Cape Town's low-income citizens.

Accuracy and completeness of recording of confirmed tuberculosis in two South African communities

BACKGROUND

Although tuberculosis (TB) treatment registers and laboratory records are essential tools for recording and reporting in TB control programmes, the accuracy and completeness of routinely collected data are seldom monitored.

OBJECTIVE

To assess the accuracy and completeness of TB treatment register data in two South African urban communities using record linkage.

METHODS

All cases of bacteriologically confirmed TB, defined as two smear-positive results and/or at least one culture-positive result, were included. Record linkage was performed between three data sources: 1) TB treatment registers, 2) the nearest central laboratory, and 3) the referral hospital laboratory.

RESULTS

The TB treatment registers had 435 TB cases recorded, of which 204 (47%) were bacteriologically confirmed. An additional 39 cases recorded as non-bacteriological cases in the TB treatment registers were reclassified as bacteriologically confirmed, and 63 bacteriologically confirmed cases were identified from the laboratory databases that were not recorded in the TB treatment registers. The final number of bacteriologically confirmed TB cases was 306, giving an increase of 50%.

CONCLUSIONS

The accuracy and completeness of the TB treatment register and central laboratory data were inadequate. A high percentage of bacteriologically confirmed cases from both laboratories were not recorded in the TB treatment registers. We are developing an electronic result management system to improve the management of laboratory results.

The impact of densification by means of informal shacks in the backyards of low-cost houses on the environment and service delivery in cape town, South Africa

This paper investigates the state-sponsored low cost housing provided to previously disadvantaged communities in the City of Cape Town. The strain imposed on municipal services by informal densification of unofficial backyard shacks was found to create unintended public health risks. Four subsidized low-cost housing communities were selected within the City of Cape Town in this cross-sectional survey. Data was obtained from 1080 persons with a response rate of 100%. Illegal electrical connections to backyard shacks that are made of flimsy materials posed increased fire risks. A high proportion of main house owners did not pay for water but sold water to backyard dwellers. The design of state-subsidised houses and the unplanned housing in the backyard added enormous pressure on the existing municipal infrastructure and the environment. Municipal water and sewerage systems and solid waste disposal cannot cope with the increased population density and poor sanitation behaviour of the inhabitants of these settlements. The low-cost housing program in South Africa requires improved management and prudent policies to cope with the densification of state-funded low-cost housing settlements.

Living in low-cost housing settlements in cape town, South Africa-the epidemiological characteristics associated with increased health vulnerability

The aim of this study was to assess the epidemiological characteristics of a representative sample of subsidized low-cost housing communities in the City of Cape Town in relation to their living conditions and their health status. Four subsidized low-cost housing communities were selected within the City of Cape Town in this cross-sectional survey. Structured interviews were administered in 336 dwellings on 173 plots. Data was obtained from 1,080 persons with a response rate of 100%. Almost all of the state-subsidized houses had one or more shacks in the backyard, increasing the occupation density and putting the municipal sanitation infrastructure under pressure. In 40% of main houses, one or more cases of diarrhea were reported during the two weeks preceding the survey, in contrast to 23% of shacks (p < 0.0007). Of the total group, 1.7% willingly disclosed that they were HIV positive, while 3.5% reported being tuberculosis (TB) positive. One of them reported having multiple drug-resistant TB. None of the HIV positive or TB positive persons was on any treatment. A reported 6.3% of the families admitted regularly eating only one meal per day, whereas 18.5% reported having only two meals per day. The shack dwellers had significantly higher education and employment status (p < 0.01), since they had to pay rent. Improvements in health intended by the rehousing process did not materialize for the recipients of low-cost housing in this study. The health vulnerability of individuals in these communities had considerable implications for the curative health services. Sanitation failures, infectious disease pressure, and environmental pollution in these communities represent a serious public health risk. The densification caused by backyard shacks, in addition, has municipal service implications and needs to be better managed. Urgent intervention is needed to allow the state-funded housing schemes to deliver the improved health that was envisaged at its inception.

Application of stereolithographic custom models for studying the impact of biofilms and mineral precipitation on fluid flow

Here we introduce the use of transparent experimental models fabricated by stereolithography for studying the impacts of biomass accumulation, minerals precipitation, and physical configuration of flow paths on liquid flow in fracture apertures. The internal configuration of the models ranged in complexity from simple geometric shapes to those that incorporate replicated surfaces of natural fractures and computationally derived fracture surfaces. High-resolution digital time-lapse imaging was employed to qualitatively observe the migration of colloidal and soluble dyes through the flow models. In this study, a Sphingomonas sp. and Sporosarcina (Bacillus) pasteurii influenced the fluid dynamics by physically altering flow paths. Microbial colonization and calcite deposition enhanced the stagnant regions adjacent to solid boundaries. Microbial growth and calcite precipitation occurred to a greater extent in areas behind the fabricated obstacles and less in high-velocity orifices.

Constraints facing the female medical practitioner in private family practice in the Western Cape

OBJECTIVES

To assess the existence and extent of employment-related problems facing female family practitioners in the context of a rapidly growing number of female doctors in South Africa.

SUBJECTS AND METHODS

A descriptive survey was conducted using bilingual questionnaires. These were posted to all 280 female family practitioners in private practice in the Western Cape.

RESULTS

Of the 280 questionnaires posted 169 were returned, but 45 of these were missampled. A response rate of 53% was obtained. The largest age category was 30-39 years. Of those not in solo practice, 68 (75%) were able to negotiate the terms of their working hours, 13 (19%) negotiated sick leave on commencing work, and only half had paid leave. Vacation leave was negotiated by 34 (50%), while only 6 (9%) discussed maternity leave with employers or colleagues. Of the 124 practices included in the survey, 6 (5%) had formal arrangements to cope with maternity leave. One hundred and seven respondents (86%) felt there was a need for maternity leave guidelines in the private sector in South Africa. Regarding practice-related problems, 33 female family practitioners (27%) reported some incidents of sexual harassment by patients. Despite these constraints, 88 respondents (71%) planned to continue working in this field.

CONCLUSION

Definite obstacles exist in private family practice with regard to working conditions, in particular the lack of national regulations regarding maternity leave and the absence of legislation on pregnancy discrimination. This has important implications for the inclusion of female doctors in group practices and managed health care organisations--private primary health care of the present and future!

Selenium reduction by a denitrifying consortium

A denitrifying bacterial consortium obtained from the Pullman, Washington wastewater treatment facility was enriched under denitrifying conditions and its ability to reduce selenite and selenate was studied. Replicate experiments at two different experimental conditions were performed. All experiments were performed under electron-acceptor limiting conditions, with acetate as the carbon source and nitrate the electron acceptor. In the first set of experiments, selenite was present, whereas, in the second set, selenate was added. A significant lag period of approximately 150 h was necessary before selenite or selenate reduction was observed. During this lag period, nitrate and nitrite use was observed. Once selenite or selenate reduction had started, nitrate and nitrite reduction was concomitant with selenium species reduction. Trace amounts of selenite were detected during the selenate reduction study. Analysis of the data indicates that, once selenium species reduction was induced, the rate of reduction was proportional to the selenium species concentration and to the biomass concentration. Furthermore, at similar biomass and contaminant concentrations, selenite reduction is approximately four times faster than selenate reduction. Copyright 1999 John Wiley & Sons, Inc.

Distribution of S(-)-zacopride-insensitive [125I]R(+)-zacopride binding sites in the rat brain and peripheral tissues

Increasing evidence indicates that the 5-HT3 receptor antagonist R(+)-zacopride labels an additional site in brain tissue that is not sensitive to 5-HT (non-5-HT R(+)-zacopride site, R(+)-site). Since the levels of R(+)-sites in the brain are relatively low, the present studies explored the use of [125I]R(+)-zacopride to label the R(+)-site; the incorporation of an [125I] atom considerably increasing the specific activity of the radioligand relative to [3H]R(+)-zacopride that has been utilised previously. Competition experiments with [125I]R(+)-zacopride (1.0 nM) binding to rat whole brain homogenates, in the presence of the 5-HT3 receptor antagonist granisetron (1.0 microM), identified that R(+)-zacopride and prazosin bound to two sites (pIC50: 7.59 and 5.28, respectively, for R(+)-zacopride; 6.75 and 4.42, respectively, for prazosin) whereas S(-)-zacopride and mianserin possessed relatively low affinity (pIC50: 4.37 and 3.80, respectively) while (-)sulpiride and 5-HT failed to compete for [125I]R(+)-zacopride binding at concentrations up to 10 microM. Autoradiographic radioligand binding studies using [125I]R(+)-zacopride (0.5 nM) identified a heterogeneous distribution of specific binding sites (defined by unlabelled R(+)-zacopride, 1.0 microM) throughout the rat brain. In the presence of a saturating concentration of granisetron (1.0 microM), highest levels of specific [125I]R(+)-zacopride, binding sites (defined by R(+)-zacopride, 1.0 microM; R(+)-site), were detected in the olfactory tubercle, thalamus, corpus callosum, colliculus, dorsal and median raphe nucleus, spinal cord and the pons (8.0-13.0 fmol/mg). Moderate densities of R(+)-sites were located in the striatum, nucleus accumbens, substantia nigra, ventral tegmental area, globus pallidus, septal nuclei, frontal cortex and cerebellum (2.0-7.9 fmol/mg). In the hippocampus, amygdala and cortical areas. R(+)-site levels were low but detectable (0.1-1.9 fmol/mg). [125I]R(+)-zacopride labelled R(+)-sites were also detected in some rat peripheral tissues, for instance kidney cortex, adrenal gland and liver (2.4-6.8 fmol/mg). The present results indicate that specific non-5-HT [125I]R(+)-zacopride sites are heterogeneously distributed throughout the rat brain and are expressed in various peripheral tissues.

Autoradiographic distribution of [3H]-(S)-zacopride-labelled 5-HT3 receptors in human brain

Autoradiographic binding studies using the 5-HT3 (5-hydroxytryptamine3) receptor radioligand, [3H]-(S)-zacopride (0.5 nM), identified a heterogeneous distribution of specific binding sites (defined by granisetron, 1 microM) throughout the human brain. Highest radiolabelled 5-HT3 receptor densities were detected in discrete nuclei within the brainstem (nucleus tractus solitarius, area postrema, spinal trigeminal nerve nucleus; 50-200 fmol/mg tissue equivalent) with more modest levels of expression in the forebrain (e.g. hippocampus, nucleus accumbens, putamen, caudate; 4-17 fmol/mg tissue equivalent). Within the hippocampal formation, radiolabelled 5-HT3 receptors were differentially distributed with highest levels in the granule cell layer of the dentate gyrus. Saturation studies with [3H]-(S)-zacopride (0.05-16 nM; non-specific binding defined by granisetron, 10 microM) binding to homogenates of human putamen indicated that [3H]-(S)-zacopride (0.05-16 nM; non-specific binding defined by granisetron, 10 microM) binding to homogenates of human putamen indicated that [3H]-(S)-zacopride labelled an apparently homogenous population of binding sites (Bmax = 72 + 7 fmol mg-1 protein, pKd = 8.69 +/- 0.09, Hill coefficient = 0.99 +/- 0.06, mean +/- SEM, n = 4). The pharmacological profile of [3H]-(S)-zacopride binding to homogenates of putamen indicated the selective labelling of the human variant of the 5-HT3 receptor. The marked differences, however, in the pharmacology (e.g. low affinity for D-tubocurarine) and relative distribution (e.g. presence of 5-HT3 receptors in the human extrapyramidal system) of 5-HT3 receptors in the human forebrain when compared with other species further necessitates caution in predicting clinical responses based on data generated in animal models of disease.

Barriers to compliance with OBRA'90 regulations in community pharmacies

OBJECTIVE

To identify which barriers have been most significant to community pharmacists in their ability to comply with the Omnibus Budget Reconciliation Act of 1990 (OBRA'90) regulations during its first year of implementation.

METHODS

Mailing of a two-page survey in April 1994.

SETTING

Four hundred randomly selected community pharmacies in the Commonwealth of Massachusetts.

PARTICIPANTS

Of 400 pharmacies surveyed, 156 surveys were completed and returned for analysis.

RESULTS

Barriers that were considered most significant to pharmacies surveyed in their ability to implement OBRA'90 regulations were excessive workload, lack of financial compensation, and patients' attitudes. Of least significance were inadequate knowledge about drugs, inadequate references, and store layout. Almost half the responding pharmacists indicated that OBRA'90 regulations had not affected or changed their practice, one-quarter of the pharmacists believed their practice was less rewarding after OBRA'90, and about one-fifth believed it was more rewarding.

CONCLUSIONS

Community pharmacists in Massachusetts are making an attempt to comply with OBRA'90, but there are specific barriers that are affecting their ability to do so. The OBRA'90 regulations appear to have had little impact on the practice of most community pharmacies. Community pharmacy management needs to examine (1) expanded roles of supportive personnel to give pharmacists more time to spend counseling patients, (2) reimbursement mechanisms for cognitive service, and (3) approaches to educating patients about these changes in the pharmacy profession.

Regulation of glutamate release by presynaptic kainate receptors in the hippocampus

Most reported actions of kainate are mediated by AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate) receptors. Here we report that, unlike AMPA which stimulates, kainate elicits a dose-dependent decrease in L-glutamate release from rat hippocampal synaptosomes and also depresses glutamatergic synaptic transmission. Brief exposure to kainate inhibited Ca(2+)-dependent [3H]L-glutamate release by up to 80%. Inhibition was reversed by kainate antagonists but not by the AMPA-selective non-competitive antagonist 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine (GYKI 52466). A corresponding reversible kainate-evoked depression of NMDA (N-methyl-D-aspartate) receptor-mediated excitatory postsynaptic currents (e.p.s.cs) was observed when AMPA receptors were blocked by GYKI 52466. The synaptic depression was preceded by a brief period of enhanced release and a small inward current was also observed. The effects of kainate were unaffected by metabotropic glutamate (mGlu), GABAA, GABAB, glycine and adenosine receptor antagonists. These results indicate that glutamate release can be modulated directly by kainate autoreceptors.

Cyclothiazide unmasks AMPA-evoked stimulation of [3H]-L-glutamate release from rat hippocampal synaptosomes

The effect of alpha-amino-3-hydroxy-5-methylisoxazolepropionate (AMPA) on Ca(2+)-sensitive, tetrodotoxin (TTX)-insensitive K(+)-stimulated [3H]-L-glutamate release from rat hippocampal synaptosomes was determined. AMPA in the presence, but not in the absence of cyclothiazide, a drug which blocks AMPA receptor desensitization, elicited a dose-dependent increase in K(+)-stimulated [3H]-L-glutamate release but had no effect on basal release. The AMPA/cyclothiazide stimulation was blocked by CNQX and by GYKI 52466, an antagonist at the cyclothiazide site. These results indicate that AMPA receptors are present on presynaptic terminals and suggest that they may play a role in the regulation of neurotransmitter release.

Quantitative analysis of the distributions of glutamatergic ligand binding sites in goldfish brain

Goldfish brain is a widely used model system for the study of the mechanisms involved in neuronal regeneration and synaptic plasticity. Because of the proposed role of glutamate receptors in these processes we have investigated the anatomical localisations of [3H]AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate), [3H]kainate, [3H]CNQX (6-cyano-7-nitroquinoxaline-2,3-dione) and [3H]L-glutamate binding sites in horizontal and sagittal sections. Binding sites for [3H]L-glutamate were the most widespread and both NMDA (N-methyl-D-aspartate) and non-NMDA sensitive components were detected. The density of [3H]kainate binding was very high in the cerebellum compared to other regions and in comparison with the other radioligands used. Conversely, relatively low amounts of [3H]AMPA binding were present with the telencephalon being the most densely labelled structure. [3H]CNQX binding was most densely localised in the tectum with the cerebellum also possessing high binding. In addition, there was a small population of [3H]CNQX binding sites located in the telencephalon and lobus vagi that appeared insensitive to AMPA and kainate.

Interaction of guanine nucleotides with [3H]kainate and 6-[3H]cyano-7-nitroquinoxaline-2,3-dione binding in goldfish brain

Recent reports have suggested that a major proportion of [3H]kainate binding in goldfish brain is to a novel form of G-protein-linked glutamate receptor. Here we confirm that guanine nucleotides decrease [3H]kainate binding in goldfish brain membranes, but that binding is also reduced to a similar extent under conditions where G-protein modulation should be minimised. Inclusion of GTP gamma S resulted in an approximately twofold decrease in the affinity of [3H]kainate binding and a 50% reduction in the apparent Bmax values in both Mg2+/Na+ and Mg2+/Na(+)-free buffer when assayed at 0 degrees C. The pharmacology of [3H]kainate binding is similar to that of well-characterised ionotropic kainate receptors but unlike that of known metabotropic glutamate receptors, with neither 1S,3R-amino-1,3-cyclopentanedicarboxylic acid (1S,3R-ACPD) nor ibotenic acid being effective competitors. The molecular mass of the [3H]kainate binding protein, as determined by radiation inactivation, was 40 kDa, similar to the subunit sizes of other lower vertebrate kainate binding proteins that are believed to comprise ligand-gated ion channels. Furthermore, GTP gamma S also inhibited the binding of the non-NMDA receptor-selective antagonist 6-[3H]cyano-7-nitroquinoxaline-2,3-dione. These data strongly suggest that the regulatory interaction between guanine nucleotides and [3H]kainate and 6-[3H]cyano-7-nitroquinoxaline-2,3-dione binding is complex and involves competition at the agonist/antagonist binding site in addition to any G-protein-mediated modulation.

Autoradiographic distribution of glutamatergic ligand binding sites in Xenopus brain: evidence for intracellular [3H]AMPA binding sites

The binding of a series of [3H]glutamatergic ligands was determined by receptor autoradiography of membrane homogenate pellets and horizontal sections of Xenopus brain. Consistent with previous reports that a 'unitary' glutamate receptor is present in Xenopus CNS, the radioligands showed similar densities of binding sites in the membrane homogenate pellets. Furthermore, [3H]kainate binding was completely displaced by AMPA or CNQX, [3H]AMPA binding was completely displaced by kainate or CNQX and [3H]CNQX binding was completely displaced by AMPA or kainate. However, in whole brain sections there were apparently 2- to 5-fold more [3H]AMPA and [3H]CNQX than [3H]kainate sites. The absence of these extra sites in broken-washed membrane preparations suggests that the additional [3H]AMPA and [3H]CNQX binding may be due to cytosolic sites. The observation that all [3H]AMPA and [3H]CNQX binding in the brain sections is displaced by kainate indicates that the putative cytosolic sites are sensitive to relatively high concentrations of kainate but that they differ from the previously characterised Xenopus CNS unitary receptors.

Molecular size of the kainate binding protein in goldfish brain determined by radiation inactivation

Radiation inactivation analysis was used to estimate the target size of a putative glutamate receptor subtype in goldfish brain. A simple, linear inactivation curve was obtained. The calculated molecular size of the [3H]kainate binding site was 33.8 kDa. The results presented here are comparable to the molecular masses determined for putative glutamate receptors in other lower vertebrates but are markedly different from the sizes of the corresponding glutamate receptor subtypes in mammalian central nervous system.

Differential binding characteristics of agonists at 5-HT3 receptor recognition sites in NG108-15 neuroblastoma-glioma cells labelled by [3H]-(S)-zacopride and [3H]granisetron

The pharmacological characteristics of 5-HT3 receptor (5-hydroxytryptamine3 receptor) recognition sites labelled with [3H]-(S)-zacopride and [3H]granisetron in membranes prepared from NG108-15 neuroblastoma-glioma cells were directly compared to investigate further differences in the binding characteristics of these two radioligands. Competition curves generated with increasing concentrations of 5-HT3 receptor ligands emphasized the pharmacological similarity of the two recognition sites labelled by [3H]-(S)-zacopride and [3H]granisetron. However, analysis of the nature of the competition curves indicated that 5-HT3 receptor agonists (5-hydroxytryptamine, 2-methyl-5-hydroxytryptamine, phenylbiguanide) and quipazine generated Hill coefficients greater than unity when the 5-HT3 receptor recognition sites were labelled with [3H]granisetron whilst these competing compounds displayed Hill coefficients of around unity when the sites were labelled with [3H]-(S)-zacopride. Competition for either [3H]-(S)-zacopride or [3H]granisetron binding by the 5-HT3 receptor antagonists granisetron and ondansetron generated Hill coefficients around unity. Furthermore, addition of unlabelled (S)-zacopride (1.0 nM) failed to alter the nature by which quipazine competed for the [3H]granisetron-labelled 5-HT3 receptor recognition site. Consistent with 5-HT3 receptors radiolabelled in rat cortical membranes, the present studies indicate that [3H]-(S)-zacopride may label a different site on the 5-HT3-receptor complex compared to [3H]granisetron.

Identification and characterisation of angiotensin II receptor subtypes in human brain

Autoradiographic and homogenate binding studies using the radioligand, [125I]angiotensin II, identified a heterogeneous distribution of specific binding sites (defined by angiotensin II, 1.0 microM) throughout the human forebrain. Highest AT receptor densities were detected in the paraventricular nucleus, median eminence, substantia nigra, putamen and caudate nucleus (2.4, 1.2, 1.0, 0.30 and 0.24 fmol/mg tissue equivalent, respectively). The AT1 receptor antagonist, losartan (1.0 microM) competed for the majority of the specific binding. [125I]Angiotensin II-specific binding (although not consistently above non-specific binding levels) was also detected in various other brain regions (e.g. amygdala, entorhinal cortex, frontal cortex, hippocampus, inferior colliculus, nucleus accumbens, parietal cortex, periaquaductal grey, superior colliculus, striate cortex, temporal cortex, thalamus). In the presence of losartan (1.0 microM), angiotensin II, saralasin, losartan and PD123177 competed for [125I]angiotensin II binding to membranes prepared from the cerebellum or substantia nigra with a rank order of affinity; angiotensin II = saralasin > PD123177 > losartan. In the presence of PD123177 (1.0 microM), the rank order of affinity of losartan and PD123177 was reversed. These studies indicate the presence of both AT1 and AT2 receptor subtypes within various regions of the human forebrain.

Scombroid poisoning. Case series of 10 incidents involving 22 patients

Scombroid poisoning is a form of ichthyosarcotoxism caused by the consumption of 'spoiled' fish of the dark meat varieties. It can be considered a mild-to-moderate form of 'food poisoning' and it occurs world-wide. Ten incidents, involving 22 patients, were reported to Tygerberg Hospital Pharmacology and Toxicology Consultation Centre in the first quarter of 1990. Cape yellowtail (Seriola lalandii) was involved in all the cases. The presenting symptoms and signs (in order of frequency) were: skin rash, diarrhoea, palpitations, headache, nausea and abdominal cramps, paraesthesia, an unusual taste sensation and breathing difficulties. The patients responded well to anti-histamines and, in most, the condition resolved within 12-24 hours. Although histamine plays an important role in the pathogenesis of scombroid poisoning, the exact mechanism is still unresolved. The condition should be recognised and not confused with a true seafood allergy. Health workers are urged to alert the authorities when outbreaks of suspected cases of scombroid poisoning are encountered in order to establish the possible cause and to prevent further cases.

Pharmacological comparison of the rat and guinea-pig cortical high affinity 5-hydroxytryptamine uptake system

The pharmacological characteristics of the high affinity [3H]5-hydroxytryptamine ([3H]5-HT) uptake system were investigated in the cerebral cortex of the rat and guinea-pig. In crude cortical synaptosomal preparations from the rat and guinea-pig, [3H]5-HT accumulated with high affinity (Km, 72 +/- 12 and 57 +/- 14 nM for rat and guinea-pig cortical synaptosomal preparation, respectively, mean +/- SEM, N = 5) and with a comparable maximum activity (Vmax, 1.22 +/- 0.21 and 0.90 +/- 0.19 pmol/min/mg protein for rat and guinea-pig cortical synaptosomal preparation, respectively, mean +/- SEM, N = 5). Competition studies employing a range of structurally diverse competing compounds showed that the [3H]5-HT uptake was pharmacologically similar in both preparations. However, citalopram possessed approximately 10-fold weaker affinity to prevent [3H]5-HT uptake in the guinea-pig preparation when compared to the rat and all of the tricyclic antidepressants assessed in the present studies (amitriptyline, nortriptyline, desipramine and imipramine) displayed higher affinity in the guinea-pig preparation when compared to the rat. It is concluded that the high affinity 5-HT uptake systems in the rat and guinea-pig cortex are similar but may not be identical.

Behavioural pharmacology of 5-HT3 receptor ligands

Extensive studies have ascribed a role for the central 5-HT3 receptor in the modulation of behaviour. Much of the work stems from the actions of potent and selective 5-HT3 receptor antagonists; these agents reduce mesolimbic dopamine initiated hyperactivity, release suppressed behaviour, reduce the reinforcing properties and withdrawal symptoms of drugs of abuse, enhance cognitive performance and modulate appetite. This article reviews the preclinical and clinical evidence implicating the 5-HT3 receptor in these indications and discusses the potential neurochemical mechanisms underlying the behavioural changes.

Pharmacological comparison of the sigma recognition site labelled by [3H]haloperidol in human and rat cerebellum

The radioligand binding characteristics of [3H]haloperidol (in the presence of spiperone, 25 nmolL-1) were investigated in rat and human cerebellar membranes. In both rat and human cerebellar membrane preparations saturation studies with [3H]haloperidol (non-specific binding defined by pentazocine, 10 mumolsL-1) demonstrated high affinity saturable specific binding to a homogenous population of binding sites (rat, Bmax 6693 +/- 1242 fmol mg-1 protein, pKD 8.33 +/- 0.08; human, Bmax 2550 +/- 437 fmol mg-1 protein, pKD 8.59 +/- 0.11; mean +/- SEM, n = 3-6). Competition studies employing a wide range of structurally diverse competing compounds displayed that the [3H]haloperidol binding site was pharmacologically similar in both preparations and comparable to sigma recognition sites previously identified in various tissues originating from different species. In addition, with reference to the potential subtypes of sigma recognition sites, the labelling of these sites by low nanomolar concentrations of [3H]haloperidol provides evidence that they belong to the sigma-1 recognition site subtype. The present findings suggest that the pharmacology of the rat and human cerebellar sigma recognition site are directly comparable and provides further supporting evidence towards the use of [3H]haloperidol radioligand binding studies in the rat to detect sigma receptor ligands with potential therapeutic activity.

Agonist interactions with 5-HT3 receptor recognition sites in the rat entorhinal cortex labelled by structurally diverse radioligands

1. The pharmacological properties of 5-HT3 receptor recognition sites labelled with [3H]-(S)-zacopride, [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330 in membranes prepared from the rat entorhinal cortex were investigated to assess the presence of cooperativity within the 5-HT3 receptor complex. 2. In rat entorhinal cortex homogenates, [3H]-(S)-zacopride, [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330 labelled homogeneous densities of recognition sites (defined by granisetron, 10 microM) with high affinity (Bmax = 75 +/- 5, 53 +/- 5, 92 +/- 6 and 79 +/- 6 fmol mg-1 protein, respectively; pKd = 9.41 +/- 0.04, 8.69 +/- 0.14, 8.81 +/- 0.06 and 10.14 +/- 0.04 for [3H]-(S)-zacopride, [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330, respectively, n = 3-8). 3. Quipazine and granisetron competed for the binding of each of the radioligands in the rat entorhinal cortex preparation at low nanomolar concentrations (pIC50; quipazine 9.38-8.51, granisetron 8.62-8.03), whilst the agonists, 5-hydroxytryptamine (5-HT), phenylbiguanide (PBG) and 2-methyl-5-HT competed at sub-micromolar concentrations (pIC50; 5-HT 7.16-6.42, PBG 7.52-6.40, 2-methyl-5-HT 7.38-6.09). 4. Competition curves generated with increasing concentrations of quipazine, PBG, 5-HT and 2-methyl-5-HT displayed Hill coefficients greater than unity when the 5-HT3 receptor recognition sites in the entorhinal cortex preparation were labelled with [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330. These competing compounds displayed Hill coefficients of around unity when the sites were labelled with [3H]-(S)-zacopride. Competition for the binding of [3H]-(S)-zacopride, [3H]-LY278,584, [3H]-granisetron and [3H]-GR67330 by granisetron generated Hill coefficients around unity.5. The nature of the interaction of competing compounds (quipazine, granisetron, PBG, 5-HT, 2-methyl-5-HT) for the [3H]-(S)-zacopride binding site in the rat entorhinal cortex preparation was not altered by the removal of the Krebs ions or the addition of the monoamine oxidase inhibitor, pargyline, to the HEPES/Krebs buffer.6. In conclusion, the present studies provide further evidence towards the presence of cooperativity within the 5-HT3 receptor macromolecule and indicate that either [3H]-(S)-zacopride labels a different site on the receptor complex from [3H]-LY278,584, [3H]-granisetron or [3H]-GR67330, or it binds in such a manner as to prevent the conformatory change in the receptor protein responsible for the cooperative binding of agonists (and quipazine).

Angiotensin-converting enzyme inhibition, angiotensin, and cognition

In these studies, we have investigated possible cognition-enhancing effects of angiotensin-converting enzyme (ACE) inhibition, and putative neurochemical correlates for these actions. In a mouse habituation model, ACE inhibitors improved basal performance and antagonized scopolamine-induced deficits. The performance of aged mice and those with lesions of the nucleus basalis was also improved. ACE inhibition also improved scopolamine-impaired performance of rats in a swim-maze model. Neurochemical studies showed that a low dose (10 micrograms/kg i.p.) of ceranapril caused significant alterations in ex vivo rat brain catecholamine levels in the nucleus accumbens, amygdala, and septum. In further studies, angiotensin II (Ang II) was shown to decrease potassium-stimulated [3H] acetylcholine release from slices of rat entorhinal and human temporal cortex, an effect that could be antagonized by the angiotensin receptor antagonist [1-sar,8-thr]Ang II. It is concluded that ACE inhibition can improve both basal and impaired performance in animal models of learning, and that this improvement may be in part a consequence of the removal by ACE inhibition of an inhibitory tone on central acetylcholine release, and/or an effect on central catecholaminergic function.

Identification of angiotensin II receptor subtypes in human brain

The present study assessed the binding characteristics of [125I]angiotensin II to slices of human cerebellum adhered to glass slides using quantitative receptor autoradiography. Specific [125I]angiotensin II binding, defined by the inclusion of unlabelled angiotensin II (1.0 microM), was detected in the molecular layer of the cerebellum (0.09 +/- 0.02 fmol/mg tissue equivalent, mean +/- s.e.m., n = 3). The angiotensin II-2 receptor subtype selective ligand, PD123177, competed for approximately 65% of the specific binding in the molecular layer whilst the remainder of the specific binding was displaced by the angiotensin II-1 receptor subtype selective ligand, DuP753. It is concluded that angiotensin II receptor subtypes exist in human brain tissue and provide potential therapeutic sites of action.

The 1989 revision of the U.S. Standard Certificates and Reports

This report examines the procedures followed in the 1989 revision of the U.S. Standard Certificates of Live Birth and Death; License and Certificate of Marriage; Certificate of Divorce, Dissolution of Marriage, or Annulment; and Reports of Fetal Death and Induced Termination of Pregnancy. It outlines the history and basic principles of the standard certificates and reports and describes the principal additions, modifications, and deletions of items. In addition, it discusses changes in the format of the standard certificates and reports as well as the implementation of the new certificates and reporting forms.

Neurochemical consequences following injection of the substance P analogue, DiMe-C7, into the rat ventral tegmental area

The effect on forebrain catecholamine- and indoleamine-related neurochemical levels was investigated following stimulation of the rat ventral tegmental area with the substance P analogue, DiMe-C7. DiMe-C7 (6.0 micrograms) induced a marked hyperactivity in rats with maximal response between 15 and 30 min following the injection. Fifteen min following the DiMe-C7 injection levels of dopamine and/or its metabolites (3,4-dihydroxyphenylacetic acid, homovanillic acid) were significantly increased in the nucleus accumbens, amygdala, entorhinal cortex and striatum relative to vehicle-injected animals. Although the increase in dopamine metabolism in the nucleus accumbens is consistent with the behavioural hyperactivity, it is concluded that other forebrain nuclei may also be involved in the mediation of the hyperactivity response.

The differential activities of R (+)- and S(-)-zacopride as 5-HT3 receptor antagonists

R(+)- and S(-)-zacopride were assessed as potential 5-HT3 receptor antagonists in behavioural and biochemical tests. The S(-)isomer was more potent than the R(+)isomer to antagonise the hyperactivity induced by the injection of amphetamine or the infusion of dopamine into the nucleus accumbens in the rat. In contrast, the R(+)isomer was more potent to reduce the aversive behaviour of mice to a brightly illuminated environment and in a marmoset human threat test, to facilitate social interaction in rats, to increase performance in a mouse habituation test and prevent a scopolamine-induced impairment, and to antagonise the inhibitory effect of 2-methyl-5-hydroxytryptamine to reduce [3H]acetylcholine release in slices of the rat entorhinal cortex. In binding assays, [3H]S(-)-zacopride and [3H]R(+)-zacopride labelled homogenous populations of high-affinity binding sites in the rat entorhinal cortex, R(+)-zacopride compete for a further 10 to 20% of the binding of [3H]R(+)/S(-)-zacopride or [3H]R(+)-zacopride in excess of that competed for by (S)(-)-zacopride. It is concluded that both isomers of zacopride have potent but different pharmacological activities, with the possibility of different recognition sites to mediate their effects.