An all oral antiemetic regimen for patients undergoing high-dose chemotherapy with peripheral blood stem cell transplant

The purpose of the study was to assess the toxicity and efficacy of an oral, combination antiemetic regimen including granisetron (Kytril; SmithKline Beecham Pharmaceuticals, Philadelphia, PA, USA) in the setting of highly emetogenic conditioning chemotherapy for stem cell transplantation. Antiemetic prophylaxis consisted of oral granisetron 2 mg once daily, oral prochlorperazine 10 mg q 6 h and oral dexamethasone 4 mg q 6 h, beginning 1 h prior to chemotherapy on each of the 4 days of chemotherapy and continuing until 24 h after the completion of high-dose chemotherapy (HDC). Patients received either CVP (cyclophosphamide 6 g/m2, VP-16 1800 mg/m2 and carboplatin 1200 mg/m2) or CTP (thiotepa 500 mg/m2 in place of VP-16) in four daily doses given over 4 h from days -4 to -1. Previously mobilized and cryopreserved peripheral blood stem cells (PBSC) were reinfused on day +1. Evaluation of nausea, emetic episodes (EE), adverse events, and rescue medications were recorded on a daily patient diary. Thirty-six patients were entered. Fifty-three percent (95% CI = 37-75%) of patients achieved complete response for emesis (CR = 0 EE/24 h) and 75% (95% CI = 58-90%) had combined complete and major response (CR+MR = 0-3 EE/24 h) during all 5 of the treatment days. During the 5 study days, the average number of patient-days with no emesis was 3.7 (74%) and with 1-3 EE was 4.3 (86%). On days -4, -3, -2, -1 and 0, the combined CR+MR rate for emesis was 97, 92, 86, 78 and 75%, respectively. Nausea was absent or mild on all 5 study days in 57% (95% CI = 37-75%). Eight patients had severe late-onset emesis occurring on days +1 to +3 after reinfusion of stem cells. No clinically significant toxicities attributable to the antiemetic regimen were observed. An all oral antiemetic regimen of granisetron, prochlorperazine and dexamethasone appears to be safe and highly effective in patients receiving multiple, daily, high-dose chemotherapy regimens. This regimen offers the advantage of cost-savings, a low side-effect profile and ease of administration in the predominately outpatient setting of HDC with peripheral blood stem cell transplant (PBSCT).

Publication bias in clinical trials and economic analyses

Publication bias is an established notion in the clinical literature; essentially, large studies or positive results are more likely to find their way into the public domain than small studies or negative results. Meta-analysis presents a focus for the problems of publication bias, seeking to summarise the evidence in a particular therapeutic area by retrieving and analysing all available clinical studies. Economic analyses are also vulnerable to publication bias, and at 3 levels: first, in the health-outcomes data available for modelling (resulting from publication bias in the clinical literature); second, in the motivations for conducting an economic analysis; and third, in repeating the process of seeking publication.

Biotechnology: a special case for health technology assessment?

Many substances produced naturally in a wide range of living organisms have been identified to be of benefit in the treatment of human disease. Current health biotechnologies recreate DNA-recombinant cellular processes in laboratory settings to produce 'natural' therapeutics: these are potentially a step forward from traditional pharmacology which has developed synthetic analogues or sought to extract products from donor material. However, with increasing financial pressures, decision makers require evidence that the benefits of biotechnologies justify their costs. The challenges experienced when evaluating the cost-effectiveness of biotechnologies are explored with reference to three examples: HA-1A human monoclonal antibody, erythropoietin and DNase. Difficulties in economic evaluation are similar to those experienced with conventional pharmaceuticals: use of short-term clinical endpoints rather than meaningful health outcomes, the artificial nature of clinical trial protocols, and uncertainty about the applicability of economic data. However, early clinical and economic assessments are required by decision-makers, particularly where biotechnology products fill major gaps in therapy. The financial structure of biotechnology companies may limit movement towards adequate clinical and economic research for health technology assessment. Governments should negotiate with the industry to promote more relevant studies, and develop policies for the managed introduction of products as evidence on effectiveness and cost expands. New technologies often present additional costs requiring reallocation of existing resources. Careful resource planning is required so that cost-effective innovation are not denied to patients.

The generalisability of pharmacoeconomic studies

Authors of pharmacoeconomic analyses understandably want their findings to apply as broadly as possible. Also, decision-makers may have to interpret the results of analyses conducted in healthcare settings other than their own. The validity of transferring or generalising results from one setting to another raises important issues for health-economic evaluation. Pharmacoeconomic analyses attempt to model the costs and benefits of alternative treatments in normal clinical practice. Usually, no single clinical study directly provides all the required information, and a variety of data sources is generally included in each analysis. Different data sources present different problems in terms of their relevance to decision-makers. At one extreme, an analysis based purely on trial outcomes and resource use may be precise, but not reflect normal practice; at the other extreme, an analysis using practice data may appear relevant, but be exposed to biases and confounding. Reviews of published studies suggest that general standards have been inadequate in the past. Reapplying such analyses in different localities may simply replicate inadequate findings. The 'perfect' should not become the enemy of the merely 'good'. Models can be helpful in decision-making, provided that they accurately communicate uncertainties in modelling and data. Even so, there will be limits to the generalisability of pharmacoeconomic models, since the required analysis differs between jurisdictions, and because of variations in normal clinical practice. The transferability of research findings re-opens the issue of credibility in pharmacoeconomics. Methodological standardisation, reporting standards and researcher independence are recognised as important factors for enhancing credibility. Where possible, pharmacoeconomic analyses should reflect the findings of systematic reviews of health outcomes to avoid the risk of biased selection of the evidence. In addition, the application of findings to individual healthcare settings must be considered, since cost effectiveness may vary markedly by setting and perspective.

Stanford-Kaiser Permanente G1 study for clinical stage I to IIA Hodgkin's disease: subtotal lymphoid irradiation versus vinblastine, methotrexate, and bleomycin chemotherapy and regional irradiation

PURPOSE

We have demonstrated that a relatively mild chemotherapy regimen, vinblastine, methotrexate, and bleomycin (VBM), and involved-field radiotherapy (IFRT) could substitute for extended-field radiotherapy in patients with favorable Hodgkin's disease (HD) who have been laparotomy-staged. The purpose of this study is to determine if VBM and regional radiotherapy can substitute for extended-field radiotherapy in favorable clinical stage (CS) I and II HD.

PATIENTS AND METHODS

Seventy-eight patients with favorable CS I to II HD were randomly assigned to subtotal lymphoid irradiation (STLI) or VBM chemotherapy and regional radiotherapy. Randomization was stratified on the basis of age, sex, number of Ann Arbor sites, histology, and institution. Patients were evaluated for freedom from progressive HD, survival, and toxicity. Results were compared with the predecessor trial in pathologically staged patients.

RESULTS

With a median follow-up period of 4 years, the rate of freedom from progressive HD was 92% (95% confidence interval [CI], 88% to 96%) for patients treated with STLI and 87% (95% CI, 81% to 93%) for patients treated with VBM and regional radiotherapy. Six of seven patients who relapsed are alive and in remission following successful second-line therapy.

CONCLUSION

Given the caveat of a small number of patients, the results of extended-field radiotherapy and VBM and regional radiotherapy are comparable with a median follow-up period of 4 years. VBM serves as a paradigm to reduce late effects in favorable early-stage HD. We do not advocate its routine use in clinical practice, but instead encourage participation in clinical trials with the objective of maintaining efficacy while reducing toxicity in CS I and II HD.

Identification of a ferritin light chain pseudogene near the glycerol kinase locus in Xp21 by cDNA amplification for identification of genomic expressed sequences

We used cDNA amplification for identification of genomic expressed sequences (CAIGES) to identify genes in the glycerol kinase region of the human X chromosome. During these investigations we identified the sequence for a ferritin light chain (FTL) pseudogene in this portion of Xp21. A human liver cDNA library was amplified by vector primers, labeled, and hybridized to Southern blots of EcoRI-digested human genomic DNA from cosmids isolated from yeast artificial chromosomes in the glycerol kinase region of Xp21. A 3.1-kb restriction fragment hybridized with the cDNA library, was subcloned and sequenced, and a 440-bp intronless sequence was found with strong similarity to the FTL coding sequence. Therefore, the FTL pseudogene that had been mapped previously to Xp22.3-21.2 was localized specifically to the glycerol kinase region. The CAIGES method permits rapid screening of genomic material and will identify genomic sequences with similarities to genes expressed in the cDNA library used to probe the cloned genomic DNA, including pseudogenes.

Relationships between hormonal profile and novelty seeking in combat-related posttraumatic stress disorder

This study examines relationships between hormonal levels and novelty seeking in a group of 27 Vietnam veterans with combat-related posttraumatic stress disorder (PTSD). Novelty seeking in the veteran sample, measured by the Cloninger Tridimensional Personality Questionnaire (TPQ), was almost twice as high as previously published norms. A distinctive pattern of significant positive correlations was found between novelty seeking scores and serum total triiodothyronine (T3), free T3, the T3/free thyroxine (FT4) ratio, urinary norepinephrine and the norepinephrine/cortisol ratio, while a negative correlation was found between novelty seeking scores and urinary cortisol levels. The findings were confirmed by t test analyses of high vs low novelty seeking subgroups and do not appear to be related simply to the severity of PTSD. These preliminary findings indicate the need to include measures of characterological traits in psychoendocrine studies of PTSD and to investigate their possible usefulness in subtyping this disorder.

Social class and chronic illness in Dublin

Information on the social class distribution of illness is scarce in Ireland. The aim of this study was to document the social class distribution of 12 common chronic conditions in middle-aged persons in Dublin. Data were collected on 3,111 individuals attending three large general practices over the course of a calendar year, and 1,024 individuals living in the same areas. Ten out of the 12 conditions studied were significantly more common in those from social classes five and six, than those from social classes one and two. Persons from social classes three and four, classes five and six, had an overall excess morbidity rate of 21% and 70% respectively. The distribution of chronic illness in middle-aged residents of Dublin is social class related.

Optometrist screening for diabetic retinopathy: evidence and environment

A recent English government-funded study has suggested that optometrists are not best suited to screening for diabetic retinopathy. This is surprising given the level of training of optometrists and their aptitude in detecting other conditions such as glaucoma and cataract. The need to screen for diabetic retinopathy is discussed. The major unresolved issue concerns the choice of screening modality, i.e. who should perform screening, when and how. A literature search is reported. Given the available evidence, to make conclusions about the relative performance of optometrists with other screeners would be inappropriate. Unresolved controversies could be addressed by new prospective studies of optometrists, and others, in screening. A pragmatic design, mirroring the current environment of care, may be important. In particular, the manner in which diabetics currently present to the health service would make screening by one modality of limited use. If thoughtfully applied, shared care concepts may achieve a broader coverage of patients with diabetics mellitus. Smaller trials investigating sub-issues, and surveys of patients and potential screeners may produce a valuable backdrop in designing appropriate studies. Issues for the development of screening schemes are considered, including the role of training, the development of protocols for care and sharing data, reimbursement and audit.

Genomic sequence of the DAX1 gene: an orphan nuclear receptor responsible for X-linked adrenal hypoplasia congenita and hypogonadotropic hypogonadism

The gene responsible for X-linked adrenal hypoplasia congenita, DAX1, encodes a member of the nuclear hormone receptor superfamily. We sequenced 8851 bp that contained the DAX1 genomic region. The DAX gene was composed of two exons and one 3.4-kilobase intron. Putative TATA and GC boxes and a putative steroidogenic factor 1 response element were present in the 5'-flanking region. Two potentially polymorphic short tandem repeats were identified. The first exon encoded two putative novel zinc finger motifs within a putative DNA binding domain and part of the ligand binding domain, and the second exon encoded the remainder of the ligand binding domain. Although the putative DNA binding domain of DAX1 does not contain substantial sequence similarity to other nuclear hormone receptor superfamily members, the putative ligand binding domain had remarkable similarity to other family members. Single-strand conformational polymorphism analysis permitted identification of three new mutations in DAX1. In conclusion, single-strand conformational polymorphism analysis facilitates identification of mutations in the DAX1 gene, and the short tandem repeats may permit linkage analysis in families in which mutations are not yet identified. We speculate that DAX1 may be the most primitive member of the nuclear hormone receptor superfamily identified in mammals.

Finding health resources on the Internet--the departure lounge

As with all other areas of research, the influence of the Internet on health economics will continue to grow. The availability of information is central to the UK health reforms and plans are afoot to create an NHS network. Harnessing the power of the Net has become a basic research skill. This involves information and data capture, work sharing and communication as well as dissemination of our own work findings. You might optimistically regard the Internet as a system of arteries and arterioles through which oxygen of information may flow effectively to those who need it. However, users are sometimes frustrated by slow access, poorly indexed information and lots of noise: successful use sometimes seems reliant on serendipity. The Departure Lounge will try to keep you up to speed with developments.

Serum triiodothyronine elevation with posttraumatic stress disorder: a cross-cultural study

This study examines the thyroid hormonal profile in Israeli combat veterans with posttraumatic stress disorder (PTSD) and compares it with the previously reported profile in American Vietnam combat veterans with PTSD. Eleven male combat veterans with PTSD were compared with 11 normal subjects. Thyroid junction was evaluated by the measurement of serum total triiodothyronine (TT3), free triiodothyronine (FT3), total thyroxine (TT4), free thyroxine (FT4), thyroxine-binding globulin (TBG), and thyroid-stimulating hormone (TSH). The mean total T3 level in the Israeli PTSD patients (160.5 ng/dL) was significantly elevated (t = 2.53, p < .02) above that of the comparison group (135.5 ng/dL). Total T3 mean levels were not significantly different between the Israeli PTSD group and two American PTSD groups, but all three PTSD groups had significantly higher total T3 levels than both Israeli and American comparison groups. This preliminary study indicates that T3 elevation in combat-related PTSD may extend across cultures and suggests that further comparison of Israeli and American PTSD and normal groups may be useful in evaluating the significance and implications of the unusual alterations in the thyroid system in PTSD.

Backboard versus mattress splint immobilization: a comparison of symptoms generated

The study objective was to compare spinal immobilization techniques to a vacuum mattress-splint (VMS) with respect to the incidence of symptoms generated by the immobilization process. We used a prospective, cross-over study in a university hospital setting. Participants consisted of 37 healthy volunteers without history of back pain or spinal disease. Interventions consisted of two phases. In Phase I, subjects were randomly assigned to be immobilized on either a wooden backboard or a mattress-splint for 30 min. The incidence and severity of any symptoms generated by the immobilization process were recorded. In Phase II, the two groups were again tested after a 2-week washout period, with the method of immobilization being reversed. Symptoms and severity were again recorded. Pain symptoms were confined to four anatomic sites: Occipital prominence, lumbosacral spine, scapulae, and cervical spine. After adjusting for the effect of order of exposure, subjects were 3.08 times more likely to have symptoms when immobilized on a backboard than when immobilized on the VMS. They were 7.88 times more likely to complain of occipital pain and 4.27 times more likely to complain of lumbosacral pain. Severity of occipital and lumbosacral pain was also significantly greater during backboard immobilization. We conclude that, when compared to a VMS, standard backboard immobilization appears to be associated with an increased incidence of symptoms in general and an increased incidence and severity of occipital and lumbosacral pain in particular.

Influence of Holter monitor and electrophysiologic study methods and efficacy criteria on the outcome of patients with ventricular tachycardia and ventricular fibrillation in the ESVEM trial

Because not all laboratories use the monitoring and stimulation protocols used in the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial, we reanalyzed the ESVEM patients' data using alternative, commonly used Holter monitor (HM) and programmed stimulation efficacy criteria to determine if different criteria would have changed the trial's conclusions. Also, because beta-blocker use and coronary artery disease frequency were not equally distributed between the two limbs in ESVEM, we reanalyzed the ESVEM data adjusting for the possible effect of these variables. In the HM limb, drug efficacy in the original ESVEM analysis was declared by reduction of total premature ventricular complexes (PVCs) by 70%, pairs by 80%, runs of 3 to 15 beats by 90%, and all ventricular tachycardia (VT) more than 15 beats by 100%. In this analysis, we examine outcome in subjects meeting two more stringent sets of criteria, (1) reduction of total PVCs by 70%, of pairs by 80%, and of all VT by 100% (new criteria set 1) and (2) reduction of total PVCs by 80%, of pairs by 90%, and of all VT by 100% (new criteria set 2). In electrophysiology (EPS) limb patients, we compared arrhythmia recurrence when efficacy was declared with triple extrastimuli as compared with maximally testing with double extrastimuli, and arrhythmia recurrence was compared in patients tested with identical versus any more aggressive protocol on drug than was used before drug. We also compared the predictive accuracy of zero versus 3 to 15, and 0 to 5, 6 to 10, and more than 10 induced beats on drug. Additionally, we compared predictive accuracy of the HM- and EP-guided limbs excluding patients on beta blockers and those with noncoronary disease. Lastly, to determine whether concordant results on HM and EPS testing would provide more accurate efficacy predictions than EP testing alone, HM recordings obtained in EPS-limb patients but not processed or used during the course of the EVSEM study were analyzed. The original ESVEM HM criteria, new set 1, and new set 2 yielded predicted drug efficacy rates of 77%, 68%, and 58%, respectively; however, arrhythmia recurrence rates were unchanged. Similarly, arrhythmia recurrence rates for patients tested with triple versus less than triple extrastimuli (p=.238), more aggressive versus identical protocols (p=.955), and 0 to 5 v 6 to 10 v more than 10 induced beats (p=.263) or 0 v 3 to 15 induced beats (p=.106) were unchanged. in the 215 (of 286) patients with coronary disease and not receiving beta blockers, there was still no difference in arrhythmia recurrence or mortality between the noninvasive and invasive limbs in ESVEM. Lastly, in patients with drug efficacy predictions by EPS testing, there was no difference in outcome in patients who had concordant versus discordant efficacy prediction by simultaneously obtained HMs. The use of more stringent testing methods and efficacy criteria would not have significantly improved the predictive accuracy of drug assessment by HM or EPS in the ESVEM trial. Additionally, excess noncoronary disease in EP-guided patients and excess beta-blocker used in HM-guided patients did not influence the results in the ESVEM trial.

Governing childbirth: the wider view

This paper seeks to 'problematize' the British government's wider intentions for public health, as they are shaped by free-market economics and technological medicine. A variety of epidemiological studies have revealed evidence of declining health among low socio-economic populations who are particularly affected by economic and social changes. The government is responding to the potential crisis by targeting specific groups of the most visible and costly victims of public ill-health. Recipients of health care with a lower public profile, such as pregnant women, are being subjected to the same policy. Current governmental strategies are regarded as an example of a medically oriented approach that focuses on special strategies for pregnancy and birth but ignores the long-term requirements for public health.

Assessing the cost effectiveness of NSAID: an international perspective

A number of factors may affect the cost effectiveness of treatments and can cause this to vary by location. These factors include the patient population, relative price levels, clinical practice patterns and incentives to health professionals and institutions such as hospitals. This paper illustrates these issues by assessing the relative cost effectiveness of 3 nonsteroidal antiinflammatory drugs (NSAID), with different levels of gastrointestinal side effects, in 3 countries. We conclude that the relative cost effectiveness of drugs is not only dependent on drug price but may also vary by country.

Relationships between thyroid hormones and symptoms in combat-related posttraumatic stress disorder

This study was designed to investigate relationships between serum thyroid hormone levels and the severity of posttraumatic stress disorder (PTSD) symptoms in a group of 65 male Vietnam combat veterans who participated as members of cohorts in an elective inpatient treatment program. Thyroid hormone measures included serum free and total triiodothyronine (T3), free and total thyroxine (T4), and thyroxine-binding globulin. To estimate symptom severity, the Clinician-Administered PTSD Scale (CAPS-2), based on DSM-III-R diagnostic criteria for PTSD, was used. Significant positive correlations were observed between free T3, total T3, total T4, and the "hyperarousal" frequency subscale score and the CAPS-2 frequency sum score. Patients with increased thyroid hormone levels and increased hyperarousal symptoms might constitute a clinically significant subtype among patients with PTSD. Alternatively, increased thyroid activity and hyperarousal symptoms may be associated with phase-related characteristics in PTSD. Research strategies for further evaluation of these preliminary findings are discussed.

A new cyclosporin derivative, SDZ-IMM-125, prolongs renal allograft survival in dogs

Previous studies in vitro and in rodent transplantation models have suggested that an analogue of cyclosporin, SDZ-IMM-125, has immunosuppressive properties at least equivalent to that of cyclosporin. As the bioavailability of the drug was considered to be greater than that of cyclosporin, it was hoped that lower doses could be used with the avoidance of nephrotoxicity. Renal allografts were undertaken between beagle dogs from two partially inbred breeding colonies. After transplantation, SDZ-IMM-125 was given orally at a dosage of 5, 7.5, 10 or 20 mg/kg/day, and graft survival compared to that in dogs given cyclosporin 10 mg/kg or in untreated animals. The results showed that SDZ-IMM-125 is immunosuppressive in dogs and prolongs graft survival up to 50 days at a dosage of 20 mg/kg/day. However, at this dose histological changes suggestive of liver toxicity were observed in one dog, and mild anaemia was produced,but there was no evidence of nephrotoxicity. Absorption profiles suggested that the drug is rapidly absorbed and metabolized, and that a more frequent daily dosage may be appropriate. Overall, there appeared to be no significant advantage for the analogue SDZ-IMM-125 over cyclosporin. The transplant model was associated with a high spontaneous renovascular thrombosis rate, particularly after cyclosporin administration, which was prevented by the daily administration of aspirin.

Successful laparoscopic repair of paraesophageal hernia

OBJECTIVE

To evaluate prospectively the safety and efficacy of laparoscopic surgical techniques in the repair of types II and III paraesophageal hernias.

DESIGN

Case series.

SETTING

Tertiary-care, university-affiliated hospitals.

PATIENTS

Twelve consecutive patients undergoing elective laparoscopic repair of type II or type III paraesophageal hernias. Patients were available for follow-up for 1 to 17 months postoperatively.

INTERVENTIONS

All patients underwent laparoscopic paraesophageal hernia reduction and repair. Eight patients with gastroesophageal reflux disease underwent concurrent laparoscopic Nissen fundoplication.

MAIN OUTCOME MEASURES

Operative times, operative complications, and estimated blood loss were recorded. Postoperative outcome measurements included length of hospital stay, postoperative complications, postoperative gastrointestinal tract symptoms, and patient satisfaction.

RESULTS

All patients had successful completion of paraesophageal hernia repair laparoscopically with no recurrences, and with an overall minor morbidity rate of 25%, major morbidity rate of 8%, and no deaths. Eight of 12 patients with concomitant reflux disease underwent successful laparoscopic Nissen fundoplication with complete control of reflux symptoms. The average hospital stay for patients with uncomplicated courses was 2.5 days. Long-term (> 6 weeks) postfundoplication symptoms occurred in 13% of those patients who underwent fundoplication. Eleven (92%) of 12 patients described good to excellent results with complete or near complete control of all preoperative symptoms.

CONCLUSIONS

Laparoscopic repair of types II and III paraesophageal hernias can be performed under elective circumstances by experienced laparoscopic surgeons, with acceptable morbidity and comparable short-term efficacy. Addition of a concomitant antireflux procedure should be reserved for those patients with clear preoperative evidence of reflux disease secondary to a mechanically defective lower esophageal sphincter. Patients with a normal lower esophageal antireflux barrier do not need a concomitant antireflux procedure.

Client-centered hypnotherapy for tinnitus: who is likely to benefit?

In this study we prospectively analyzed 41 patients, 15 females and 26 males with a mean age of 54, who underwent three sessions of client-centered hypnotherapy for their tinnitus. Of these patients, 28 (68%) showed some benefit for their tinnitus 3 months after completing their hypnosis, and 13 (32%) showed no evidence of improvement for their tinnitus. Hearing loss was associated with a nonbeneficial outcome for tinnitus treated with hypnotherapy. Of the nonbeneficial group, 46% had a hearing loss of 30 db or more in their better-hearing ear compared to less than 15% in the beneficial group, a significant difference (X2 = 6.34, df = 1, p < 0.02). Client-centered hypnotherapy can be offered to anyone who wants to have therapy for their tinnitus; in those with significant hearing loss the benefit may be less.

The effects of the nematode peptide, KHEYLRFamide (AF2), on the somatic musculature of the parasitic nematode Ascaris suum

AF2 is an endogenous RFamide-like peptide from the parasitic nematode Ascaris suum. The potent stimulatory effects of this peptide on the somatic musculature of Ascaris strongly suggest that it may have an important role in the motornervous system. Here we have investigated the possibility that AF2 may elicit a stimulatory action on Ascaris muscle by potentiating the actions of the excitatory cholinergic motonervous system either pre-synaptically, post-synaptically or both. In in vitro pharmacological experiments AF2 produced a dose-dependent increase in the frequency and amplitude of spontaneous contractions of Ascaris muscle strip which lasted for more than 1 h after a 3 min application of AF2 (10 nM-10 microM; N = 7). In addition, AF2 (100 nM) potentiated the contraction elicited by ACh by 43 +/- 9% (P < 0.01; N = 8). In electrophysiological recordings from muscle cells, AF2 (10-100 nM; N = 10) potentiated the amplitude of EJPs (excitatory junction potentials). For 100 nM AF2, the potentiation of the EJP was 218 +/- 48% (N = 7; P < 0.01). This effect reversed after a wash of 10 min. AF2 did not potentiate the depolarization of the muscle cell elicited by bath applied ACh. These latter two observations are consistent with a presynpatic action of AF2. AF2 (10-100 nM) generated spontaneous muscle cell action potentials in previously quiescent cells. This effect took more than 1 h to wash out. These observations are discussed in terms of the paralysis of Ascaris that is elicited by AF2.