Etanercept and efalizumab for the treatment of psoriasis: a systematic review

OBJECTIVES

To evaluate the clinical effectiveness, safety, tolerability and cost-effectiveness of etanercept and efalizumab for the treatment of moderate to severe chronic plaque psoriasis.

DATA SOURCES

Major electronic databases and several Internet resources were searched up to April 2004.

REVIEW METHODS

Systematic reviews were undertaken of the efficacy, safety and economic reviews of etanercept and efalizumab. An existing systematic review of the efficacy and safety of other treatments was also updated. Economic models supplied by the manufacturers of etanercept and efalizumab were critiqued. An economic model was then developed of etanercept and efalizumab in the treatment of moderate to severe chronic plaque psoriasis.

RESULTS

The review of the clinical evidence identified a total of 39 published and three unpublished studies: eight randomised controlled trials (RCTs) of the efficacy of etanercept (three trials) and efalizumab (five); 10 studies of the adverse effects of the interventions; and 24 RCTs of the efficacy of the other treatments for moderate to severe psoriasis. The trials of the efficacy of the interventions were all double-blind and placebo-controlled trials and generally of good quality, but three of the five efalizumab trials were poorly reported. A total of 1347 patients were included in the etanercept trials and 2963 in the efalizumab trials. Data on the efficacy of etanercept 25 mg twice a week for 12 weeks were available from three RCTs. On average, active treatment resulted in 62% of patients achieving a Psoriasis Area and Severity Index (PASI) 50, 33% achieving a PASI 75, 11% achieving a PASI 90 and 40% were assessed as clear or almost clear. These figures are not adjusted for changes relative to placebo. Improvement in quality of life as assessed by mean percentage change in Dermatology Life Quality Index (DLQI) was around 59% with etanercept 25 mg twice a week compared with 9% with placebo, and all mean differences that could be calculated were statistically significantly in favour of etanercept. Data on the efficacy of etanercept 50 mg twice a week for 12 weeks were available from two RCTs. Across the two trials, the proportion of patients achieving PASI 50, 75 and 90 was 76, 49 and 21%, respectively; the pooled relative risks were all statistically significantly in favour of etanercept. The findings for mean PASI after treatment, mean percentage change in PASI from baseline and mean percentage change in DLQI also demonstrated the efficacy of etanercept treatment. Evidence from one RCT indicates that the response to etanercept is maintained post-treatment, at least in the medium term, and data from uncontrolled follow-up phases reflect and extend these findings. Efalizumab at a dose of 1 mg/kg once a week subcutaneously was studied in five RCTs. Across these trials, 12 weeks of active treatment resulted in an average of 55% of patients achieving PASI 50, 27% PASI 75, 4.3% PASI 90 and 27% clear or minimal psoriasis status. These figures are not adjusted for changes relative to placebo. There is no evidence from RCTs that the response to efalizumab 1 mg/kg once a week is maintained when treatment continues beyond 12 weeks, and long-term follow-up data relate to a range of doses and are poorly reported and so cannot be used to draw even tentative conclusions regarding the long-term efficacy of efalizumab. Uncontrolled data from trial follow-up suggest that time to relapse may be around 60 days. No data indicating the existence or absence of any rebound in psoriasis after discontinuation of efalizumab were identified. There is no evidence relating to the efficacy of efalizumab upon retreatment. A mixed treatment comparison analysis found a higher response rate in terms of PASI 50, 75 and 90 with etanercept than with efalizumab. Injection site reactions appear to be the most common adverse effects of etanercept. Overall, etanercept appears to be well tolerated in short- and long-term use, although many of the long-term data are not from patients with psoriasis. Headache, chills and, to a lesser extent, nausea, myalgia, pain and fever are the common adverse events associated with efalizumab. Overall, withdrawal rates due to adverse events are low. Longer term data for efalizumab are not readily available for evaluation, but the adverse events data up to 3 years appear to reflect those over 12 weeks and to remain stable. Unfortunately, few data for serious infections and serious adverse events with efalizumab are available. For the primary analysis comparing etanercept, efalizumab and supportive care, the results of the York Model suggest that the biological therapies would only be cost-effective for all patients with moderate to severe psoriasis if the NHS were willing to pay over pound 60,000 per QALY gained. In patients with poor baseline quality of life (fourth quartile DLQI), efalizumab, etanercept 25 mg (intermittent), etanercept 25 mg (continuous) and etanercept 50 mg (intermittent) would be cost-effective as part of a treatment sequence if the NHS were willing to pay pound 45,000, pound 35,000, pound 45,000 and pound 65,000 per QALY gained, respectively. In patients who are also at high risk of inpatient hospitalisation (21 days per annum), these therapies would be cost-effective as part of a sequence as long as the NHS were willingness to pay pound 25,000, pound 20,000, pound 25,000 and pound 45,000 per QALY gained, respectively. As part of a secondary analysis including a wider range of systemic therapies as comparators, the York Model found that it would only be cost-effective to use etanercept and efalizumab in a sequence after methotrexate, ciclosporin and Fumaderm.

CONCLUSIONS

Clinical trial data indicate that both etanercept and efalizumab are efficacious in patients who are eligible for systemic therapy, but the economic evaluation demonstrates that these biological therapies are likely to be cost-effective only in patients with poor baseline QoL and who are at risk of hospitalisation. Efficacy trials conducted in the specific population for which etanercept and efalizumab are licensed are required, as are long-term comparisons of etanercept and efalizumab with other treatments for moderate to severe psoriasis. Long-term efficacy trials and safety/tolerability data for patients treated with etanercept or efalizumab are required, as are trials on the response of specific subtypes of psoriasis to different drugs. Research on the rate of inpatient hospitalisation in patients with moderate to severe psoriasis is warranted, and the effect of treatment on this rate.

Undetectable salivary testosterone in young women with premature ovarian failure

BACKGROUND

The extent of androgen deficiency in young women with premature ovarian failure (POF) is unclear.

AIM

Cross-sectional study of androgen status in young women with POF.

PATIENTS

Twenty women with POF: six had Turner syndrome (group A); eight had iatrogenic POF either secondary to bilateral oophorectomy or treatment of malignancy (group B); and six had idiopathic POF (group C). The median age was 30.5 years (range 19-39); in groups B and C the median duration of ovarian failure was 10.0 years (range 1-35).

METHODS

After a 2-month wash-out period without sex steroid replacement (SSR), serum testosterone (T), androstenedione (A4), dehydroepiandrosterone (DHEAS), SHBG, salivary testosterone (SalT) and the free androgen index [FAI = (serum T/SHBG) x 100] were measured.

RESULTS

Median serum A4 was 4.6 nmol/l (10th, 90th centiles, 3.6, 5.1) and DHEAS was 3.2 micromol/l (10th, 90th centiles, 2.3, 9.3). Although median serum T was relatively low at 1.4 nmol/l (10th, 90th centiles, 1.1, 1.7), median SHBG was also low at 34 nmol/l (10th, 90th centiles 22.2, 67.5) and the median calculated FAI was within the normal range at 3.7 (10th, 90th centiles, 2.3, 7.0). However, SalT was undetectable in almost all subjects in the three groups of POF.

CONCLUSIONS

Serum T and SHBG are relatively low in young women with POF and their FAI is therefore within the normal range. However, SalT, which measures free testosterone, is consistently low to undetectable in these young women with POF. The reliability of the FAI as a marker of androgen deficiency remains questionable.

Use of case fatality and readmission measures to compare hospital performance in gynaecology

OBJECTIVE

To identify suitable outcome measures for comparing gynaecology performance between hospitals.

DESIGN

Analysis of routinely collected statistics.

SETTING

England. POPULATION A total of 1.45 million gynaecology admissions in 1999/2001.

METHODS

The database used was a linked file of English NHS hospital admission statistics and death certificate data. Case fatality rates (CFRs)and emergency readmission (ERA) rates were calculated for different components of gynaecology workload. Funnel plots, using age-sex standardised measures, were displayed to compare the outcomes.

MAIN OUTCOME MEASURES

CFRs and ERA rates.

RESULTS

The CFR within 30 days after admission for patients with cancer was 5.1%. These patients accounted for only 3% of all the admissions but for 73% of all 30-day deaths. All other 30-day CFRs were extremely low-below 0.5%. The 30-day ERA rates ranged from 1.8% after day case care to 17.4% after emergency admissions for people who did not have an operation. Funnel plots showed considerable variation between hospitals for ERA after day case care but not after elective abdominal hysterectomy.

CONCLUSIONS

There are no measures of mortality that could be used routinely and meaningfully to compare the performance of gynaecology units. We suggest that two suitable comparative measures of outcome, derivable from routine hospital statistics, are 30-day ERA rates after day case admissions and after elective abdominal hysterectomy, excluding those records with a cancer diagnosis. These measures are relatively homogeneous with respect to their likely rates of adverse events and have sufficient numbers to produce potentially useful comparative results.

Role of viral replication in extrahepatic syndromes related to hepatitis B virus infection

Approximately 20% of patients with hepatitis B virus (HBV) infection may experience extrahepatic disease. These manifestations include a viral prodrome with a serum sickness-like syndrome, polyarteritis nodosa, glomerulonephritis, as well as various neurological and dermatologic diseases amongst other manifestations. The viral pathogenesis is not well understood and has been difficult to study due to the lack of an animal model of HBV-related extrahepatic disease. Deposition of immune complexes and activation of the complement cascade has been most widely studied. However, circulating immune complexes are physiologic and occur more frequently than extrahepatic disease. Also, HBV-related extrahepatic syndromes occur in the absence of immune complex formation. Several studies support the notion that HBV replication in extrahepatic tissues may also precipitate disease but extrahepatic replication has commonly been observed without any apparent cytopathic or immune related tissue damage. It is clear that suppression of viral replication with antiviral therapy or spontaneous viral clearance positively correlates with resolution of extrahepatic disease. The use of continuous immunosuppressive therapy has largely been abandoned with the advent of robust antiviral strategies to manage disease. These data support the notion that a combination of factors including inadequate clearance immune complexes and viral replication in extrahepatic tissues play an important role in the pathogenesis. This conceptual framework is potentially significant as it emphasizes the importance of antiviral treatment in the management of extrahepatic disease.

Clinical effectiveness, tolerability and cost-effectiveness of newer drugs for epilepsy in adults: a systematic review and economic evaluation

OBJECTIVES

To examine the clinical effectiveness, tolerability and cost-effectiveness of gabapentin (GBP), lamotrigine (LTG), levetiracetam (LEV), oxcarbazepine (OXC), tiagabine (TGB), topiramate (TPM) and vigabatrin (VGB) for epilepsy in adults.

DATA SOURCES

Electronic databases. Internet resources. Pharmaceutical company submissions.

REVIEW METHODS

Selected studies were screened and quality assessed. Separate analyses assessed clinical effectiveness, serious, rare and long-term adverse events and cost-effectiveness. An integrated economic analysis incorporating information on costs and effects of newer and older antiepileptic drugs (AEDs) was performed to give direct comparisons of long-term costs and benefits.

RESULTS

A total of 212 studies were included in the review. All included systematic reviews were Cochrane reviews and of good quality. The quality of randomised controlled trials (RCTs) was variable. Assessment was hampered by poor reporting of methods of randomisation, allocation concealment and blinding. Few of the non-randomised studies were of good quality. The main weakness of the economic evaluations was inappropriate use of the cost-minimisation design. The included systematic reviews reported that newer AEDs were effective as adjunctive therapy compared to placebo. For newer versus older drugs, data were available for all three monotherapy AEDs, although data for OXC and TPM were limited. There was limited, poor-quality evidence of a significant improvement in cognitive function with LTG and OXC compared with older AEDs. However, there were no consistent statistically significant differences in other clinical outcomes, including proportion of seizure-free patients. No studies assessed effectiveness of AEDs in people with intellectual disabilities or in pregnant women. There was very little evidence to assess the effectiveness of AEDs in the elderly; no significant differences were found between LTG and carbamazepine monotherapy. Sixty-seven RCTs compared adjunctive therapy with placebo, older AEDs or other newer AEDs. For newer AEDs versus placebo, a trend was observed in favour of newer drugs, and there was evidence of statistically significant differences in proportion of responders favouring newer drugs. However, it was not possible to assess long-term effectiveness. Most trials were conducted in patients with partial seizures. For newer AEDs versus older drugs, there was no evidence to assess the effectiveness of LEV, LTG or OXC, and evidence for other newer drugs was limited to single studies. Trials only included patients with partial seizures and follow-up was relatively short. There was no evidence to assess effectiveness of adjunctive LEV, OXC or TPM versus other newer drugs, and there were no time to event or cognitive data. No studies assessed the effectiveness of adjunctive AEDs in the elderly or pregnant women. There was some evidence from one study (GBP versus LTG) that both drugs have some beneficial effect on behaviour in people with learning disabilities. Eighty RCTs reported the incidence of adverse events. There was no consistent or convincing evidence to draw any conclusions concerning relative safety and tolerability of newer AEDs compared with each other, older AEDs or placebo. The integrated economic analysis for monotherapy for newly diagnosed patients with partial seizures showed that older AEDs were more likely to be cost-effective, although there was considerable uncertainty in these results. The integrated analysis suggested that newer AEDs used as adjunctive therapy for refractory patients with partial seizures were more effective and more costly than continuing with existing treatment alone. Combination therapy, involving new AEDs, may be cost-effective at a threshold willingness to pay per quality-adjusted life year (QALY) greater than 20,000 pounds, depending on patients' previous treatment history. There was, again, considerable uncertainty in these results. There were few data available to determine effectiveness of treatments for patients with generalised seizures. LTG and VPA showed similar health benefits when used as monotherapy. VPA was less costly and was likely to be cost-effective. The analysis indicated that TPM might be cost-effective when used as an adjunctive therapy, with an estimated incremental cost-effectiveness ratio of 34,500 pounds compared with continuing current treatment alone.

CONCLUSIONS

There was little good-quality evidence from clinical trials to support the use of newer monotherapy or adjunctive therapy AEDs over older drugs, or to support the use of one newer AED in preference to another. In general, data relating to clinical effectiveness, safety and tolerability failed to demonstrate consistent and statistically significant differences between the drugs. The exception was comparisons between newer adjunctive AEDs and placebo, where significant differences favoured newer AEDs. However, trials often had relatively short-term treatment durations and often failed to limit recruitment to either partial or generalised onset seizures, thus limiting the applicability of the data. Newer AEDs, used as monotherapy, may be cost-effective for the treatment of patients who have experienced adverse events with older AEDs, who have failed to respond to the older drugs, or where such drugs are contraindicated. The integrated economic analysis also suggested that newer AEDs used as adjunctive therapy may be cost-effective compared with the continuing current treatment alone given a QALY of about 20,000 pounds. There is a need for more direct comparisons of the different AEDs within clinical trials, considering different treatment sequences within both monotherapy and adjunctive therapy. Length of follow-up also needs to be considered. Trials are needed that recruit patients with either partial or generalised seizures; that investigate effectiveness and cost-effectiveness in patients with generalised onset seizures and that investigate effectiveness in specific populations of epilepsy patients, as well as studies evaluating cognitive outcomes to use more stringent testing protocols and to adopt a more consistent approach in assessing outcomes. Further research is also required to assess the quality of life within trials of epilepsy therapy using preference-based measures of outcomes that generate cost-effectiveness data. Future RCTs should use CONSORT guidelines; and observational data to provide information on the use of AEDs in actual practice, including details of treatment sequences and doses.

Dementia care provision in rural Scotland: service users' and carers' experiences

There has been global neglect of service users' and carers' experiences of dementia care provision in rural areas. The present paper draws on a qualitative study of service provision for people with dementia and their carers in remote and rural Scotland. It draws on interviews with 15 people with dementia and 16 carers to explore their views about health and social dementia care service provision in rural Scotland. A further 14 carers of people with dementia participated in one of three focus groups. The paper discusses perceived gaps in services as well as positive aspects of dementia service provision which service users attribute to living in a rural area. The important issues this raises for the development of dementia care provision in rural areas are briefly discussed.

Molecular mechanisms of membrane polarity in renal epithelial cells

Exciting discoveries in the last decade have cast light onto the fundamental mechanisms that underlie polarized trafficking in epithelial cells. It is now clear that epithelial cell membrane asymmetry is achieved by a combination of intracellular sorting operations, vectorial delivery mechanisms and plasmalemma-specific fusion and retention processes. Several well-defined signals that specify polarized segregation, sorting, or retention processes have, now, been described in a number of proteins. The intracellular machineries that decode and act on these signals are beginning to be described. In addition, the nature of the molecules that associate with intracellular trafficking vesicles to coordinate polarized delivery, tethering, docking, and fusion are also becoming understood. Combined with direct visualization of polarized sorting processes with new technologies in live-cell fluorescent microscopy, new and surprising insights into these once-elusive trafficking processes are emerging. Here we provide a review of these recent advances within an historically relevant context.

Aboriginal perspective on middle ear disease in the arid zone of Western Australia

OBJECTIVES

To explore perceptions, knowledge and experience of otitis media (OM) and barriers to compliance with treatment among Aboriginal people of the Kalgoorlie-Boulder area, Western Australia.

METHODS

This qualitative applied research study is based on a holistic design. We conducted structured interviews with three community focus groups, 56 key informants, and 22 mothers of babies known to have suffered from OM. Written records of interviews were checked with participants. The three sources of data enabled comparison and verification of results.

RESULTS

People were concerned about serious consequences of OM, especially deafness and learning difficulties. Since early disease may have no localizing symptoms, not surprisingly, people had limited understanding of the aetiology of OM and were often only aware of disease once ear discharge was visible. Nevertheless, they usually sought treatment for non-specific symptoms. Competing demands in people's daily lives and the unpleasant, intensive nature of treatment result in families becoming resigned to a child's chronic ear discharge. Someone other than the biological mother within the extended family may be responsible for administering treatments. Half the carers thought passive smoking may predispose children to OM and 70% suggested clearing the nasal passages to prevent OM. Results of surgery were viewed positively but specialist services were not always readily accessible.

CONCLUSIONS

Since responsibility for treatment may not lie with the biological mother, awareness campaigns must target the entire community. As early OM may be asymptomatic, health personnel should be encouraged to do otoscopy on all children with non-specific symptoms.

Flumazenil does not affect intracortical motor excitability in humans: a transcranial magnetic stimulation study

OBJECTIVE

The motor cortex may be subject to tonic inhibitory drive. One inhibitory mechanism is supported by activity at benzodiazepine (BZP) receptors. In this study we investigate whether or not the BZP antagonist, flumazenil, increases cortical motor excitability in humans.

METHODS

Eight healthy subjects received a 1 mg intravenous (i.v.) loading dose of flumazenil followed by a 0.5 mg i.v. infusion over the next 30 min. Before, during, and 1 h after flumazenil infusion, we measured cortical motor excitability using transcranial magnetic stimulation (TMS). This included resting motor threshold (rMT), paired-pulse measurements of intracortical inhibition and facilitation (ICI and ICF), recruitment curve (RC), and silent period (SP). We also measured F response and compound muscle action potential (CMAP) with peripheral nerve stimulation. The study was carried out using a randomized, double-blind crossover design controlled with a saline infusion.

RESULTS

None of the measures of cortical or peripheral excitability were significantly affected by drug administration.

CONCLUSIONS

Our findings suggest that flumazenil has no effect on cortical motor excitability in normal humans.

SIGNIFICANCE

There does not appear to be any tonic activity at benzodiazepine receptors in the normal resting human motor cortex.

Evaluation of food safety education for consumers

Traditionally, nutrition educators have used a fairly global approach to teach food safety by teaching a broad range of safe food handling behaviors in the expectation that this will lead to the avoidance of foodborne illness. This approach can be confusing and lead to evaluation data that are difficult to interpret. This article suggests that food safety education and evaluation in the future be organized around five behavioral constructs: practice personal hygiene, cook foods adequately, avoid cross-contamination, keep foods at safe temperatures, and avoid food from unsafe sources. These five constructs are derived from data on actual outbreaks and estimated incidences of foodborne illness. Research is needed to establish reliable and valid evaluation measures for these five behavioral constructs. Evaluation instruments can be tailored to fit specific education programs. If evaluation instruments focus on these five behavior areas, the result will be meaningful evaluation data that can be more easily summarized across food safety education programs for consumers.

Referrals to a secondary care dental clinic for anxious adult patients: implications for treatment

OBJECTIVES

This study aimed to determine the methods suggested by general dental practitioners for management of patients with dental anxiety whom they refer to a dental hospital setting, the treatment modalities eventually used with such patients and the relationship between patients previous sedation experience and the current referral.

METHODS

Consecutive referral letters (n = 125) for management of patients with dental anxiety over a 16 month period were analysed for content, including reason for referral and suggested treatment modalities. Patient records were also examined for previous sedation experience.

RESULTS

From 115 referrals eligible for analysis, the dentists requested management of anxiety using pharmacological methods in 113 referrals with only two referrals mentioning psychologically-based treatments. In secondary care, 29% of the adult referrals opted for dental treatment using psychological techniques alone.

CONCLUSIONS

In spite of the efficacy of psychological treatments for dental anxiety, primary and secondary care dentists appear not to be suggesting or promoting their use for patients with dental anxiety. Further research into the availablility of, and barriers to accessing the full range of services for those with dental anxiety, including patient perspectives, needs to be undertaken.

Viral induction of type 2 diabetes and autoimmune liver disease

Cross-sectional studies performed worldwide have shown that hepatitis C virus (HCV) infection is linked with type 2 diabetes, but these endocrine and liver diseases have an insidious onset, and it has been difficult to establish that patients acquire HCV infection before the development of diabetes. It is likely that investigations in small animal models or in vitro systems will be required to determine whether a causal relationship of HCV infection and the development of diabetes can be established. We have developed an in vitro model to study the viral induction of primary biliary cirrhosis (PBC) based on the phenotype of the diseased biliary epithelial cells. PBC patients make antimitochondrial antibodies and also express proteins reactive to these antibodies on their biliary epithelium. In coculture studies we have found that normal biliary epithelial cells develop the phenotypic manifestation of PBC in vitro specifically when cultivated with lymph nodes from PBC patients and not with relevant liver disease control subjects. We have also cloned a novel human retrovirus from a PBC biliary epithelium cDNA library and confirmed that the development of the PBC phenotype in vitro coincides with the presence of this virus. In clinical trials using antiretroviral therapy, we have observed a reversal of ductopenia as well as improvements in histology and hepatic biochemistry in patients with PBC. As Koch's postulates are not readily applicable to chronic diseases, we have used cocultivation viral transmission model in vitro and antimicrobial clinical studies in vivo to help establish a causal relationship with a retrovirus infection and the phenotypic manifestation of disease.

Hemophilic pseudotumor of the chest

We report the progressive imaging findings of a case of hemophilic pseudotumor of the chest, not previously described. The pseudotumor, although originally extrapleural, has gradually enlarged and eroded into a bronchus, producing a bronchopleural fistula.

Visual and visuospatial development in young children with Williams syndrome

This study investigated the relation between sensory visual problems and the severity of visuospatial difficulties in a large group of young children with Williams' syndrome (WS). A questionnaire describing visual and associated problems was completed by the families of 108 children with WS and detailed follow-up assessments were conducted, including visual, spatial, motor, visuocognitive, and linguistic tests of 73 of these children (mean age 7 years 3 months; 40 males, 73 females). Children with WS showed a much higher incidence of common paediatric sensory vision problems (strabismus, visual acuity loss, amblyopia, reduced stereopsis) than normally developing children. It was found that delays with respect to age normative values increased with age on all tests. No significant correlation was found between the presence of a visual deficit and the severity of the visuospatial problems, suggesting that the difficulties children with WS have in understanding spatial arrangements are not simply a result of their earlier sensory visual problems. Results confirm the dissociation between visuospatial and language abilities in children with WS, and support the neurobiological model of a split between ventral and dorsal stream processing of visual information with a generalized deficit in dorsal stream processing in young children with WS.

Autoimmune liver disease. Current standards, future directions

The diagnosis and management of autoimmune hepatitis continues to evolve as new diagnostic tests and new therapies are added to the armamentarium. Also encouraging are the advances in the understanding of the human immune system and its involvement in the origin and course of auto immune diseases in general and in the variants of autoimmune liver disease. Promising changes are expected in the next few years as new medications become available to the practicing hepatologist. New immune tests may allow therapies to be customized to patients, and antiviral therapies may also eventually be used in the management of this autoimmune liver diseases.

Food safety education: what should we be teaching to consumers?

Food safety education is most effective when messages are targeted toward changing behaviors most likely to result in foodborne illness. The five major control factors for pathogens are personal hygiene, adequate cooking, avoiding cross-contamination, keeping food at safe temperatures, and avoiding foods from unsafe sources. Pathogens associated with poor personal hygiene have the highest incidence and costs. Inadequate cooking and cross-contamination have lower incidence. Keeping food at safe temperatures and unsafe food sources have the lowest incidence, although costs per case are sometimes very high. We recommend that consumer food safety educators primarily focus on hand washing, adequate cooking, and avoiding cross-contamination. Secondary messages should focus on keeping food at safe temperatures and avoiding food from an unsafe source. Evaluation tools are needed to evaluate self-reported behavior changes. The evaluation questions must focus on salient behaviors that are most likely to result in foodborne illnesses and must withstand rigorous standards of reliability and validity.

Cultural sensitivity and day care workers. Examination of a worksite based cardiovascular disease prevention project

Reaching workers in small worksites presents economic and access barriers for occupational health nurses. Some barriers can be overcome through strategies based on cultural sensitivity. Day care centers employ young, low income, mostly minority women in settings with few workers onsite at any one center. These settings were used to develop a culturally sensitive approach tested through onsite cardiovascular screening, informal interviews, and discussion of behavior change for better health. The study examined both the impact of the Healthier People Health Risk Appraisal (HPHRA) as a culturally appropriate recruitment strategy to involve a group of child day care workers in a cardiovascular disease (CVD) screening and risk reduction program and the effect of that program on observable CVD measures. Faculty and students from an institution of higher education forged a trust relationship with day care providers at nine day care centers in a large metropolitan area. Cardiovascular health was the impetus for the project because minority populations in the southeastern United States have high heart attack and stroke mortality and morbidity rates. Participation rates in the project increased from 26% of the day care workers in the first year of the project to 73% when long term relationships were built on culturally appropriate strategies. The project's culturally sensitive educational intervention focused on individual risks and lifestyle. Statistical analysis of outcomes of the intervention and personal interviews demonstrated the improvement of cardiovascular status in the day care workers. This psychosocial approach can provide the foundation for culturally sensitive care in larger occupational and community settings.

Identification of the Ly49L protein: evidence for activating counterparts to inhibitory Ly49 proteins

Previous studies have indicated that NK cells from different strains of inbred mice may express distinct Ly49 repertoires. Screening of NK cells from the CBA/J mouse for inhibitory and activating Ly49s revealed a novel DAP12-associated receptor that was immunoprecipitated with the Ly49G-specific mAb 4D11. Degenerate primers were designed to amplify and clone Ly49 cDNAs from CBA/J NK cells. A novel activating Ly49 cDNA was identified, which bears strong homology to the partially sequenced Ly49l gene found in C57BL/6 mice. Transfection of Ly49l into a DAP12+ cell line and subsequent immunoprecipitation experiments showed that Ly49L is likely the activating Ly49 detected by the 4DD11 antibody in CBA/J NK cells. Antibody-mediated cross-linking of Ly49L induced DAP12 phosphorylation, providing evidence that Ly49L is a functional activating receptor. Comparison of the extracellular domains of Ly49 family members indicates that all known activating members have an inhibitory counterpart with a highly related extracellular region.

Bion and binocular vision

The author describes his contact with Bion over a twenty-year period, from Bion's supervision of his control case in London in 1960 to the period from 1968 to 1978 when they were both working in Los Angeles. He outlines Bion's views on the use of 'instinct' and intuition in patient observation, the depressive position in patient and analyst, and memory and desire as impediments to knowledge of 'ultimate reality'. Some case material is presented, illustrating how Bion's ideas, particularly concerning attacks on linking, informed the course of the treatment. The author then discusses Freud's, Klein's and Bion's approaches to the problem of resistance, Bion's expansion of some of Klein's ideas, his definitions of psychosis and his formulation concerning thoughts that develop before thinking. The author then argues how essential it is for the analyst to differentiate between primitive projections from the patient that are pre-verbal attempts to communicate a state of mind and those that are an expression of hostility or control. He then discusses the importance of understanding idealizing projections and differentiating these from a healthy positive transference. He concludes by characterising Bion's way of working in terms of his humility, his courage and, fundamentally, his use of his intuitive binocular mind.

Thalamic terminal fields of individual axons from the ventral part of the dentate nucleus of the cerebellum in Macaca mulatta

This study examined organization of the projection from the dentate nucleus of the cerebellum to the ventral lateral nucleus (VL) of the thalamus in Macaca mulatta. Small injections of biotinylated dextran amine were placed in the ventral parts of dentate nuclei. The distribution of all contralateral terminal fields in the thalamus was charted, and representative individual axons that terminated in the VL were traced in serial sections under the light microscope. These axons were reconstructed with all their branches and terminal fields in the thalamus. The geometry and size of the terminal fields as well as the number and distribution of boutons and neurons in them were analyzed. The terminal fields of all labeled axons were distributed widely over the VL either singly or in clusters. Two types of axons were found: simple axons formed only one terminal field and complex axons formed multiple terminal fields at a distance. Individual terminal fields were focal, had the form of flattened discs, and generated up to 200 boutons distributed between 10 and 29 nerve cell bodies. These findings suggest that a simple axon activates a small group of neurons at one site. The complex axons, in turn, influence similar size cell groups at different VL locations. The total number of boutons generated by a single complex axon was up to 300. Future studies should determine whether simple axons could be branches of complex axons that took off below the thalamus. The results reveal a complex organization of the input from the ventral dentate to the VL that only partially fits into the traditional concept of somatotopic organization of the nucleus.

Comparison of the healing rates and complications of three four-layer bandage regimens

This randomised controlled study compares the healing rates, complications and patient and staff acceptability of three four-layer bandage regimens for leg ulcers. A total of 149 patients were recruited into the study, of whom 50 received the original Charing Cross system (CX4L), 50 a modified Charing Cross system (Parema) and 49 a commercially available kit, Robinson Ultra Four (Robinson). No significant difference was found in the healing rates of the three systems. Overall 12 weeks' healing was 65%, while the 20-week healing rates for the individual systems were 87% (CX4L), 84% (Parema) and 83% (Robinson). Analysis of known risk factors for delayed healing showed that no bandaging system had an advantage over the others. Staff familiarity resulted in an initial preference for the CX4L but there was no bandage preference by the end of the study. The data suggest that none of the systems has an advantage over the others and that cost savings can be made by pursuing a competitive pricing policy.

Continuum approach to car-following models

A continuum version of the car-following Bando model is developed using a series expansion of the headway in terms of the density. This continuum model obeys the same stability criterion as its discrete counterpart. To compare both models we show that traveling wave solutions of the Bando model are very similar to those of the continuum model in the limit of small changes of headway. As the change of headway across the wave increases the solutions gradually diverge. Our transformation relating headway to density enables predictions of the global impact and characteristics of any car-following model using the analogous continuum model. In contrast, we show that the conventional continuum models which account for effects of pressure and dispersion predict behavior which is distinct from the global behavior of discrete models.

Hepatic manifestations of familial patent ductus venosus in adults

BACKGROUND

The ductus venosus connects the umbilical vein to the inferior vena cava during fetal life and subsequently closes rapidly after birth. It is known as patent ductus venosus when it remains patent in adulthood.

PATIENTS

A 43 year old man with a history of panhypopituitarism presented with recurrent bouts of pedal oedema associated with fatigue, hypoalbuminaemia, and elevated prothrombin time. An ultrasound examination of his abdomen with Doppler revealed notable attenuation of the main portal vein with diminished intrahepatic branches; a computed tomography scan with angiography revealed a large collateral vein within the liver consistent with a patent ductus venosus. Sequential liver biopsies showed a considerable reduction in the calibre and number of the portal veins. His younger brother, who was diagnosed with alcohol related cirrhosis, suffered from intermittent bouts of encephalopathy and was found to have the same vascular lesion. A third brother was found to have a patent ductus venosus as well as two large hepatic masses consistent with focal nodular hyperplasia.

CONCLUSION

The syndrome of familial patent ductus venosus has only previously been described in three infant brothers who presented with hepatic encephalopathy and fatty degeneration of the liver. This report documents three brothers with a patent ductus venosus presenting in adulthood with different manifestations of liver disease. The presence of the same vascular anomaly in three brothers is highly suggestive of a recessive genetic trait with an anatomical manifestation of patent ductus venosus.

Is disease management relevant in Europe: some evidence from the United Kingdom

Actions or approaches by the pharmaceutical industry, going under the general label 'disease management', have become very popular in the USA. However, there appears to be uncertainty about what exactly 'disease management' is and about the extent to which it can be applied in Europe. A postal questionnaire on disease management was sent out to senior personnel in the UK NHS and pharmaceutical industry. The survey aimed to explore the meaning of the term 'disease management' and its relevance to the NHS, assessing how perspectives differed between the two groups of respondents. Views on the barriers to the increase of disease management within the NHS were also sought. Finally, respondents were asked to indicate any involvement in joint disease management ventures. Most respondents agreed that disease management included estimating the total cost of managing a disease (92%) and the devising of clinical guidelines (97%). When asked about the particular role a pharmaceutical company might play, the level of agreement dropped in both groups of respondents, but by a greater degree in the NHS group. In defining disease management for themselves, just 4% of respondents referred to a 'partnership' between the NHS and the pharmaceutical industry. It would seem that, for the majority of respondents, 'joint ventures' are a possible, but not a necessary, means of undertaking disease management. Almost 30% of NHS respondents and 55% of industry respondents indicated that their Authority or company had experience of a joint venture in disease management. The major perceived barrier to an increase in disease management was NHS suspicion of pharmaceutical companies (86% of all respondents), with the difficulty in drawing up contracts coming a close second (79%).

Benefits of using telemedicine and first results in Bosnia and Herzegovina

In October 1996 the Institute of Pathology with the Radiology and Ophthalmology Clinic of the university hospital of Sarajevo joined the experimental telemedicine project SHARED. Two months after the project began, dermatology, paediatrics and haematology were also included. During the first phase we had 40 teleconsultations that showed us the benefits of using telemedicine. Our opinions and the opinions of the pathologist in Milan were similar for most of the biopsies (78%). The total time required for the consultation for the first 40 cases was 372 min, or 9.3 min each, on average. The longest consultation time was 25 min. The largest number of images was 44 per case, the smallest four. Because of problems of infrastructure and lack of experts, telemedicine will be important to a small country like Bosnia and Herzegovina.

Alleged allergy to local anaesthetic drugs

OBJECTIVE

To identify the true nature of an acute reaction in 25 patients initially diagnosed as allergic to local anaesthetic drugs.

SETTING

University General and Dental Hospitals.

INTERVENTIONS

Detailed review of each patient's previous exposure to local anaesthetic drugs and of the history of the acute event was followed up with challenge testing by intradermal injection.

RESULTS

One patient was subsequently found to be genuinely allergic to a local anaesthetic drug of the amide type. A wide range of conditions had actually precipitated the other adverse reactions, but all could be classified under three major headings: an immunological condition to a different antigen; a manifestation of anxiety; or an iatrogenic problem.

CONCLUSION

Local anaesthetic allergy is rare, but does occur. All reactions to local anaesthetic drugs must be assessed carefully and specialist referral may be appropriate.

The prevalence of Tourette syndrome in a mainstream school population

The aim of this study was to ascertain accurately the prevalence of Tourette syndrome (TS) in a mainstream school population. All year 9 pupils (aged 13 to 14 years) in a mainstream secondary school were investigated using a two-stage procedure. Standardized questionnaires were completed by parents, teachers, and pupils. Class observations were also carried out to identify tics. Those pupils identified as having tics underwent a semistructured interview to determine whether they had TS according to DSM-III-R criteria. Data were available from at least one source (parent, teacher, or self-reports) on 166 of the 167 pupils in the year. Five subjects were identified as having TS according to DSM-III-R criteria, yielding a prevalence estimate of 299 per 10,000 pupils in this age group. The results of this study suggest that TS in the community as a whole is more common and milder than those prevalence estimates and descriptions of the disorder based on TS encountered in secondary or tertiary health-care service settings.

Mutagenesis of the aspartic acid ligands in human serum transferrin: lobe-lobe interaction and conformation as revealed by antibody, receptor-binding and iron-release studies

Recombinant non-glycosylated human serum transferrin and mutants in which the liganding aspartic acid (D) in one or both lobes was changed to a serine residue (S) were produced in a mammalian cell system and purified from the tissue culture media. Significant downfield shifts of 20, 30, and 45 nm in the absorption maxima were found for the D63S-hTF, D392S-hTF and the double mutant, D63S/D392S-hTF when compared to wild-type hTF. A monoclonal antibody to a sequential epitope in the C-lobe of hTF reported affinity differences between the apo- and iron-forms of each mutant and the control. Cell-binding studies performed under the same buffer conditions used for the antibody work clearly showed that the mutated lobe(s) had an open cleft. It is not clear whether the receptor itself may play a role in promoting the open conformation or whether the iron remains in the cleft.

Pro-haemorrhagic effects of calcium antagonists: a comparison of isradipine and atenolol on ex vivo platelet function in hypertensive subjects

It has been suggested that long term treatment with calcium antagonist drugs might inhibit platelet function and lead to an anti-atheromatous effect. However recent data have also suggested that such an effect might increase mortality due to an increased incidence of gastrointestinal bleeding. We identified 43 subjects from general practice with uncomplicated mild to moderate hypertension to compare the effects of the calcium antagonist isradipine with that of the beta-blocker atenolol on platelet function, plasma beta-thromboglobulin levels, fibrinolysis, and serum lipids in a randomised double-blind parallel group study. After careful evaluation to exclude concomitant aspirin use, only 24 subjects were eligible to enter the study. While isradipine and atenolol produced comparable and clinically significant falls in blood pressure (167 +/- 2/102 +/- 1 to 153 +/- 3/91 +/- 2 mm Hg, and 165 +/- 2/101 +/- 1 to 156 +/- 4/91 +/- 2 mm Hg, respectively), neither drug produced a detectable effect on ex vivo platelet aggregation, platelet retention, or thromboxane generation with adrenaline, collagen, adenosine-di-phosphate, or platelet activating factor. However a decrease in plasma beta-thromboglobulin levels was observed which reached statistical significance (P < 0.05) after 12 weeks treatment in the isradipine but not the atenolol group. A 39% reduction with isradipine compared with 34% following atenolol treatment. Euglobulin clot lysis time was not altered by either drug. Serum cholesterol concentrations were also unaltered by drug treatment. Therapeutic doses of the calcium antagonist isradipine may produce a minor indirect effect on platelet function after several weeks of treatment. However, this is of doubtful clinical importance and may simply reflect an effect of lowered blood pressure on platelet function.

Phenytoin-oxacillin interactions in normal and uremic sera

Displacement of phenytoin (90% bound to albumin) by other strongly albumin-bound drugs such as salicylate and valproic acid may result in an increase in pharmacologically active free concentrations. The antibiotic oxacillin is also strongly bound to albumin and is often administered to patients receiving phenytoin. Oxacillin at a concentration of 15 micrograms/ml caused no significant displacement of phenytoin in a serum pool prepared from patients receiving phenytoin. However, a significant increase in the free phenytoin concentration was seen at an oxacillin concentration of 50 micrograms/ml. We also prepared a serum pool from uremic patients and another from patients with hypoalbuminemia and supplemented both of them with phenytoin. Significant increases in the free phenytoin concentration occurred with both 15- and 50-microgram/ml concentrations of oxacillin. In one hypoalbuminemic patient receiving both phenytoin and intravenous high-dose oxacillin, the free phenytoin fraction was 22.5% before oxacillin therapy, 24.1% 12 hours after first dose of oxacillin, and 27.2% after 60 hours, indicating the possibility of in vivo displacement of phenytoin by oxacillin. We conclude that the phenytoin-oxacillin interaction is not significant at lower dosages of oxacillin usually prescribed for oral therapy. However, the interaction may be significant at high concentrations of oxacillin, especially in patients with hypoalbuminemia or uremia.

Comparison of quantitative HCV RNA assays in chronic hepatitis C

We compared the relative sensitivities of first-and-second generation branched nucleotide assays (Quantiplex HCV RNA 1.0 and 2.0, respectively, Chiron, Emeryville, Calif) for the detection of hepatitis C virus (HCV) RNA to that of a commercially available quantitative reverse transcriptase polymerase chain reaction (RT-PCR) method (Monitor, Roche Molecular Systems, Nutley, NJ) in 53 patients with chronic hepatitis C. The sensitivities of the second-generation branched DNA (bDNA) and RT-PCR assays were similar (91% and 92%, respectively), and both were significantly more sensitive (P < .001) than the first-generation method. Moreover, both assays detected HCV RNA in all 11 patients with type 2a, 2b, or 3a genotypes vs 45% with the HCV RNA 1.0 bDNA assay. We examined 174 serum samples by the bDNA 2.0 and RT-PCR assays. Major quantification differences were noted on a given specimen with the RT-PCR method reporting values an average 41-fold lower (range, 0-703-fold) than those obtained with the bDNA assay. We conclude that both methods can be used to detect HCV RNA in patients who are infected with the genotypes that are most commonly encountered in the United States. The HCV RNA 2.0 bDNA assay may offer advantages when attempting to quantify high-level viremia.

Prevalence of herpesviridae and hepatitis B virus DNA in the liver of patients with non-A, non-B fulminant hepatic failure

Members of the herpes virus family and hepatitis B virus (HBV) have been implicated as etiologic agents in non-A, non-B (NANB) fulminant hepatic failure (FHF), but the frequency of infection with these agents has not been established using appropriate controls. To examine this issue, we studied 50 NANB FHF patients and 104 liver transplant recipients from North America and Europe. Hepatic DNA was analyzed by polymerase chain reaction (PCR) for evidence of Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus I (HSV I) and II (HSV II), varicella-zoster virus (VZV), and human herpes virus-6 (HHV-6) nucleic acid sequences. The prevalence of HBV was assessed in North American subjects only. HSV I, HSV II, VZV, and HHV-6 viral sequences were not observed in any samples. Three of 50 FHF (6%) and 14 of 104 control patients (13%) were positive for CMV DNA. Two of 50 FHF (4%) and 10 of 104 control patients (10%) had EBV DNA, and HBV DNA was observed in 3 of 10 North American FHF patients (30%) and 3 of 59 controls (5%) without serum markers for HBV infection. The finding of HBV DNA in the liver of seronegative controls from North America but not Europe suggests that occult hepatitis B sequences in patients with NANB FHF may simply reflect geographic differences. The majority of cryptogenic FHF cases cannot be attributed to infection with herpes viruses or HBV.

Neuronal diversity in the subiculum: correlations with the effects of somatostatin on intrinsic properties and on GABA-mediated IPSPs in vitro

1. We used intracellular current-clamp techniques to record from 33 ventral subicular neurons in slices or rat hippocampal formation. Presumed pyramidal neurons were characterized by their responses to depolarizing current pulses as either intrinsically burst firing (IB) or regular spiking (RS). Within the subiculum, IB cells were encountered most frequently in the deep cell layer, whereas RS cells were encountered most frequently in the superficial cell layer. IB cells had more depolarized resting potentials, lower input resistances, and more sag in their voltage responses to hyperpolarizing current pulses. 2. Somatostatin (5 microM) applied in the bathing medium caused a hyperpolarization and reduction in input resistance. These effects were of greater magnitude in IB cells. Somatostatin had no effect on sag in either cell type. These effects of somatostatin were unchanged in the presence of gamma-aminobutyric acid (GABA) receptor antagonists. 3. In a series of experiments conducted in RS cells only, somatostatin reduced the amplitude of the late but not the early component of evoked biphasic inhibitory postsynaptic potentials (IPSPs). 4. A second series of experiments was conducted in RS and IB cells. Somatostatin reduced the amplitude of pharmacologically isolated GABAA IPSPS in both cell types. In IB cells but not RS cells there was a correlation between this effect and the somatostatin-induced hyperpolarization. Somatostatin also reduced the amplitude of isolated GABAB IPSPS in both cell types, but more so in IB cells. 5. Somatostatin had no effect on the reversal potential of either IPSP in either cell type and no effect on the GABAA-mediated conductance in either cell type. In contrast, the GABAB-mediated conductance was reduced, especially in IB cells. 6. The effects of somatostatin on GABAA IPSPS are principally a result of membrane shunting and reductions in ionic driving force, but these mechanisms do not account for the reduction in GABAB IPSPS. 7. We suggest that the combined effects of somatostatin are likely to alter the balance between fast and slow inhibition and to do so more in IB cells than in RS cells.

HLA-C typing of eleven Papua New Guineans: identification of an HLA-Cw4/Cw2 hybrid allele

HLA-C polymorphism of 11 individuals from Papua New Guinea was studied by serology and DNA typing (SSP ARMS-PCR). To resolve certain discrepancies HLA-C alleles were cloned and sequenced. Five alleles were identified by sequencing, four of which; Cw*0304, Cw*0401, Cw*12022 and Cw*1502 have been identified previously in other populations. The fifth allele, which was found in four individuals is a novel HLA-C allele. The new allele, called HLA-Cw*0403 is most similar to HLA-Cw*0401, differing by 10 nucleotides, 9 of which are located in the region from nucleotide 98 to 218. This region of Cw*0403 is identical to both HLA-Cw*0201 and Cw*02022. The 9 nucleotide differences between Cw*0401 and Cw*0403 result in 6 amino acid differences in the alpha 1 domain. These amino acids in Cw*0403 may contribute to the serological typing of some, but not all Cw*0403 expressing cells. The Final difference between Cw*0401 and Cw*0403 is a coding substitution at nucleotide 979 in exon 5. The guanine found in Cw*0403 is identical to all HLA-C alleles except HLA-Cw*0401, which has an adenine. The Cw*0403 allele was most likely formed by a gene conversion event between Cw*02 and Cw*04, involving a minimum of 121 to a maximum of 215 nucleotides.

Reevaluation of synaptic relationships of cerebellar terminals in the ventral lateral nucleus of the rhesus monkey thalamus based on serial section analysis and three-dimensional reconstruction

Terminals of cerebellar afferents (CB) to different regions of the ventral lateral nucleus (VL) of the rhesus monkey thalamus were labeled with wheat germ agglutinin-horseradish peroxidase following injections into the dentate nucleus. Synaptic relationships of 17 CB with projection neuron dendrites (PNd) and local circuit neuron dendrites (LCNd) were analyzed in serial ultrathin sections from dorsal and ventral VL regions, which are known to differ cytoarchitecturally and functionally. Three terminals were reconstructed using three-dimensional (3D) computer image analysis techniques to obtain volumetric and planar measurements. CB in the ventral VL were often flat and elongated with synaptic vesicles arranged in clusters. Each CB was engaged with one PNd and one to four LCNd. A single bouton formed 8-50 synaptic contacts, with those on PNd outnumbering the ones on LCNd 4.1:1. Only some CB in the ventral VL were engaged in complex synaptic arrangements such as triads and serial synapses. Most CB in the dorsal VL displayed a roundish shape and numerous uniformly distributed synaptic vesicles. They formed 5-25 synaptic contacts with a 3:1 ratio of contacts on PNd compared with those on LCNd. CB in the dorsal VL participated in a variety of complex synaptic arrangements. Two types of triads were found: classic with CB, PNd and LCNd, and unconventional with CB and two LCNd. CB were also involved in serial synapses with two LCNd or LCNd and another PNd, and serial sequential synapses with two LCNd and a PNd. Three glomerulus-like structures were encountered in the dorsal VL. 3D reconstruction and volumetric measurements revealed that synaptic contacts formed by CB on PNd had varying shapes and sizes (0.022-0.274 microns2). Synapses formed on LCNd were larger (0.09-0.407 microns2). The total area of all active zones of a single CB on LCNd was either equal to or about 40% smaller than that of synapses on PNd. The entire active zone area comprised 1-1.6% of the total CB surface area and did not seem to correlate with the volume. Synaptic contacts formed by associated LCNd on PNd in complex arrangements were usually small (0.021-0.044 micron2). The results suggest that: synapses formed by CB on PNd and LCNd, and synapses formed by LCNd on PNd may differ in strength; a variety of different circuits participate in the processing of cerebellar afferent information in the primate VL; and these circuits differ in functionally different VL subdivisions.

Effects of somatostatin and related peptides on the membrane potential and input resistance of rat ventral subicular neurons, in vitro

The effects of bath-applied somatostatin (SS), and related peptides on the membrane potential and input resistance of 117 ventral subicular neurons were investigated by intracellular recording in rat brain slices. Electrophysiological properties, which included burst-firing in response to depolarizing current pulses, indicated that the neurons studied were of the pyramidal type. For the 89 cells analyzed quantitatively, membrane potential was -69.1 +/- 0.3 mV (mean +/- S.E.) and input resistance was 23.9 +/- 0.5 megohms. SS (5 microM) caused a hyperpolarization of 3.4 +/- 0.3 mV (n = 9) and reduced input resistance by 16 +/- 3.1% (n = 6). SS D-Trp8, somatostatin, octreotide, CGP 23996 and MK 678 shared these effects, but somatostatin was inactive. SS effects persisted when bathing solutions contained tetrodotoxin, reduced calcium and elevated magnesium concentrations and when both of these treatments were combined. They were unaltered by antagonists at gamma-aminobutyric acid receptors or at ionotropic glutamate receptors. The effects of MK 678, SS, SS D-Trp8 and somatostatin were concentration-dependent, and these peptides were equipotent at 500 nM and at 5 microM. For MK 678, the EC50 was 316 nM for the hyperpolarization and 90 nM for the reduction in input resistance. We conclude that SS acts directly on pyramidal neurons of the rat subiculum to cause a hyperpolarization and a decrease in input resistance. We suggest that these effects are mediated by the SSTR2 receptor subtype.

Accurate synapse regeneration despite ablation of the distal axon segment

In each body ganglion of the leech Hirudo medicinalis there is a single S-cell. After an S-cell axon is severed, it regenerates along its surviving distal segment and reconnects with its synaptic target, the axon of the neighbouring S-cell. In approximately half the cases the regenerating axon forms a temporary electrical synapse specifically with the distal segment, which remains active and connected to the target, thereby functioning as a splice until regeneration is complete. To determine whether the distal axon segment is required for successful regeneration, distal segments of severed S-cell axons were ablated by intracellular injection of bacterial protease. Fifty-seven preparations were examined from 2 to 212 days after injection of the axon segment. The extent of S-cell axon regeneration was assessed electrophysiologically by intracellular and extracellular recording, and anatomically by intracellular injection of markers followed by light microscopy and electron microscopy. The S-cell axons regenerated successfully in almost 90% of animals examined after 2 weeks or more. In a further four animals the target S-cell was ablated in addition to the distal axon segment, permanently disrupting conduction along the S-cell pathway. Nevertheless, the regenerating axon grew along its usual pathway and there was no evidence that alternative connections were formed. It is concluded that, although the distal axon segment can provide a means for rapid functional repair, the segment is not required for reliable regeneration of the axon along its usual pathway and accurate formation of an electrical synapse.