Kava for the treatment of generalised anxiety disorder (K-GAD): study protocol for a randomised controlled trial

BACKGROUND

Generalised anxiety disorder (GAD) is a chronic and pervasive condition that generates high levels of psychological stress, and it is difficult to treat in the long term. Current pharmacotherapeutic options for GAD are in some cases only modestly effective, and may elicit undesirable side effects. Through targeted actions on the gamma-aminobutyric acid (GABA) pathway, the South Pacific medicinal plant kava (Piper methysticum) is a non-addictive, non-hypnotic anxiolytic with the potential to treat GAD. The evidence for the efficacy of kava for treating anxiety has been affirmed through clinical trials and meta-analyses. Recent research has also served to lessen safety concerns regarding the use of kava due to hepatotoxic risk, which is reflected in a recent German court overturning the previous kava ban in that country (which may in turn influence a reinstatement by the European Union). The aim of current research is to assess the efficacy of an 'aqueous noble cultivar rootstock extract' of kava in GAD in a larger longer term study. In addition, we plan to investigate the pharmacogenomic influence of GABA transporters on response, effects of kava on gene expression, and for the first time, the neurobiological correlates of treatment response via functional and metabolic imaging.

METHODS/DESIGN

This clinical trial is funded by the Australian National Health and Medical Research Council (APP1063383) and co-funded by MediHerb (Integria Healthcare (Australia) Pty. Ltd). The study is a phase III, multi-site, two-arm, 18-week, randomised, double-blind, placebo-controlled study using an aqueous extract of noble kava cultivar (standardised to 240 mg of kavalactones per day) versus matching placebo in 210 currently anxious participants with diagnosed GAD who are non-medicated. The study takes place at two sites: the Centre for Human Psychopharmacology (Swinburne University of Technology), Hawthorn, Melbourne, Australia; and the Academic Discipline of Psychiatry (The University of Queensland) based at the Royal Brisbane and Women's Hospital, Herston, Brisbane, Australia. Written informed consent will be obtained from each participant prior to commencement in the study. The primary outcome is the Structured Interview Guide for the Hamilton Anxiety Rating Scale (SIGH-A). The secondary outcomes involve a range of scales that assess affective disorder symptoms and quality of life outcomes, in addition to the study of mediating biomarkers of response (assessed via genomics and neuroimaging).

DISCUSSION

If this study demonstrates positive findings in support of the superiority of kava over placebo in the treatment of GAD, and also is shown to be safe, then this plant-medicine can be considered a 'first-line' therapy for GAD. Genomic and neuroimaging data may reveal clinical response patterns and provide more evidence of the neurobiological activity of the plant extract.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov: NCT02219880 Date: 13 August 2014:.

Functional Activation during the Rapid Visual Information Processing Task in a Middle Aged Cohort: An fMRI Study

The Rapid Visual Information Processing (RVIP) task, a serial discrimination task where task performance believed to reflect sustained attention capabilities, is widely used in behavioural research and increasingly in neuroimaging studies. To date, functional neuroimaging research into the RVIP has been undertaken using block analyses, reflecting the sustained processing involved in the task, but not necessarily the transient processes associated with individual trial performance. Furthermore, this research has been limited to young cohorts. This study assessed the behavioural and functional magnetic resonance imaging (fMRI) outcomes of the RVIP task using both block and event-related analyses in a healthy middle aged cohort (mean age = 53.56 years, n = 16). The results show that the version of the RVIP used here is sensitive to changes in attentional demand processes with participants achieving a 43% accuracy hit rate in the experimental task compared with 96% accuracy in the control task. As shown by previous research, the block analysis revealed an increase in activation in a network of frontal, parietal, occipital and cerebellar regions. The event related analysis showed a similar network of activation, seemingly omitting regions involved in the processing of the task (as shown in the block analysis), such as occipital areas and the thalamus, providing an indication of a network of regions involved in correct trial performance. Frontal (superior and inferior frontal gryi), parietal (precuenus, inferior parietal lobe) and cerebellar regions were shown to be active in both the block and event-related analyses, suggesting their importance in sustained attention/vigilance. These networks and the differences between them are discussed in detail, as well as implications for future research in middle aged cohorts.

Effect of analgesic modality on outcome following open liver surgery: a systematic review of postoperative analgesia

Postoperative analgesia following liver resection remains controversial. The traditional standard of care of thoracic epidural is increasingly questioned due to perceived associated complications and delays to recovery. Evidence supporting alternative analgesic techniques is emerging however best practice is not yet established. This review aimed to evaluate the literature to assess the optimum analgesic technique following liver resection. A systematic review was conducted of trials evaluating analgesic methods in open liver surgery. Primary outcome was the postoperative complication rate. Secondary outcomes were length of stay and pain scores. Fourteen trials matching the inclusion criteria were analysed. No difference was observed in systemic complication rates between analgesic modalities. Epidural was associated with prolonged length of stay when compared with continuous wound infiltration and intrathecal morphine. Epidural offered equivalent or superior pain scores when compared to alternative techniques. In summary current evidence suggests alternative analgesic modalities may provide favorable recovery outcomes following liver surgery but consistent evidence is limited. Epidurals provide superior pain relief to alternatives but this does not translate into reduced length of stay or complication rate following liver surgery.

The living with asthma study: issues affecting the perceived health and well-being of Irish adults with asthma

INTRODUCTION

Ireland has the fourth highest incidence of asthma in the world, with an estimated 14.7 % of the population having asthma, making it the most common chronic disease in childhood and the most common respiratory illness in Ireland.

METHOD

The aim of this qualitative enquiry, involving participant focus groups, was to investigate the health and well-being of Irish adults who have asthma, with particular interest in the influences on their health and well-being. The study population was recruited from the Asthma Society of Ireland database of members. Data were collected in eight focus group interviews and analysed for themes.

RESULTS

Asthma was found to have a significant impact on the health and well-being of participants due to symptom experience, treatments they had to undertake, and the repercussions of uncontrollable events or triggers. The unrelenting pressure of managing their asthma took a toll on many of the participants, who felt their lifestyle had changed dramatically and they had lost some or all of their control over their health and well-being.

Bowel management in spinal cord injury patients

Spinal cord injuries are common in the United States, affecting approximately 12,000 people per year. Most of these patients lack normal bowel function. The pattern of dysfunction varies with the spinal level involved. Most patients use a bowel management program, and elements of successful programs are discussed. Surgical treatment, when indicated, could include sacral nerve stimulation, Malone antegrade continence enema, and colostomy.

An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe

We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope (136)Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). In the test setup described here, Ba ions can be produced in liquid xenon or vacuum and collected on a clean substrate. This substrate is then removed to an analysis chamber under vacuum, where laser-induced thermal desorption and RIS are used with time-of-flight mass spectroscopy for positive identification of the barium decay product.

A field programmable gate array-based time-resolved scaler for collinear laser spectroscopy with bunched radioactive potassium beams

A new data acquisition system including a Field Programmable Gate Array (FPGA) based time-resolved scaler was developed for laser-induced fluorescence and beam bunch coincidence measurements. The FPGA scaler was tested in a collinear laser-spectroscopy experiment on radioactive (37)K at the BEam COoler and LAser spectroscopy (BECOLA) facility at the National Superconducting Cyclotron Laboratory at Michigan State University. A 1.29 μs bunch width from the buncher and a bunch repetition rate of 2.5 Hz led to a background suppression factor of 3.1 × 10(5) in resonant photon detection measurements. The hyperfine structure of (37)K and its isotope shift relative to the stable (39)K were determined using 5 × 10(4) s(-1) (37)K ions injected into the BECOLA beam line. The obtained hyperfine coupling constants A((2)S(1/2)) = 120.3(1.4) MHz, A((2)P(1/2)) = 15.2(1.1) MHz, and A((2)P(3/2)) = 1.4(8) MHz, and the isotope shift δν(39, 37) = -264(3) MHz are consistent with the previously determined values, where available.

Case Report: A case of hypertrophic lupus erythematosus with negative CD123 staining and absence of transepidermal elimination of elastin

We report the case of a 49-year-old male with clinical and histological findings consistent with hypertrophic lupus erythematosus (HLE). HLE must be clinically and histologically differentiated from keratoacanthoma, hypertrophic lichen planus, squamous cell carcinoma and plaque type psoriasis. CD123 positivity and transepidermal elimination of elastin have recently been reported as tools to distinguish HLE. Interestingly, in this case, biopsies of two separate lesions failed to reveal these two features. The etiology of this discrepancy is unknown and further studies are needed to clarify the utility of CD123 positivity and transepidermal elimination of elastin in the diagnosis of hypertrophic lupus erythematosus.

Patients' lived seclusion experience in acute psychiatric hospital in the United States: a qualitative study

The findings revealed that the patients perceived seclusion as an intervention that is punitive and a means used by the staff to exert control. Patients perceived that staff incitements and lack of communication skills led to their being secluded. The findings provided recommendations and strategies for seclusion reduction that were based on the patients' first-hand seclusion experiences. This phenomenological study used Husserlian's philosophy to explore and describe the lived experiences of psychiatric patients who were secluded at a free-standing acute care hospital located in South-western United States (US). The study is crucial because very few studies have been conducted in this area in the US. The study examined a purposive sample of 20 patients, 3 days post-seclusion. Data were generated through face-to-face, semi-structured interviews incorporating open-ended questions and probes to facilitate discussion until saturation was reached. Interviews were transcribed verbatim and data analysed using Colaizzi's seven steps method. Results were described according to the themes and subthemes identified. Findings uncovered four themes: (1) alone in the world; (2) staff exert power and control; (3) resentment towards staff; and (4) time for meditation. The findings from this study illuminated the views surrounding patients' seclusion experience. It provided first-hand information on the patients' seclusion experience that might be helpful to the mental health professionals in the seclusion reduction process.

Circumferential resection margin (CRM) positivity after MRI assessment and adjuvant treatment in 189 patients undergoing rectal cancer resection

PURPOSE

The management of rectal cancer relies on accurate MRI staging. Multi-modal treatments can downstage rectal cancer prior to surgery and may have an effect on MRI accuracy. We aim to correlate the findings of MRI staging of rectal cancer with histological analysis, the effect of neoadjuvant therapy on this and the implications of circumferential resection margin (CRM) positivity following neoadjuvant therapy.

METHODS

An analysis of histological data and radiological staging of all cases of rectal cancer in a single centre between 2006 and 2011 were conducted.

RESULTS

Two hundred forty-one patients had histologically proved rectal cancer during the study period. One hundred eighty-two patients underwent resection. Median age was 66.6 years, and male to female ratio was 13:5. R1 resection rate was 11.1%. MRI assessments of the circumferential resection margin in patients without neoadjuvant radiotherapy were 93.6 and 88.1% in patients who underwent neoadjuvant radiotherapy. Eighteen patients had predicted positive margins following chemoradiotherapy, of which 38.9% had an involved CRM on histological analysis.

CONCLUSIONS

MRI assessment of the circumferential resection margin in rectal cancer is associated with high accuracy. Neoadjuvant chemoradiotherapy has a detrimental effect on this accuracy, although accuracy remains high. In the presence of persistently predicted positive margins, complete resection remains achievable but may necessitate a more radical approach to resection.

Omega-3 supplementation improves cognition and modifies brain activation in young adults

OBJECTIVE

The current study aimed to investigate the effects of eicosapentaenoic acid (EPA)-rich and docosahexaenoic acid (DHA)-rich supplementations on cognitive performance and functional brain activation.

DESIGN

A double-blind, counterbalanced, crossover design, with a 30-day washout period between two supplementation periods (EPA-rich and DHA-rich) was employed. Functional magnetic resonance imaging scans were obtained during performance of Stroop and Spatial Working Memory tasks prior to supplementation and after each 30-day supplementation period.

RESULTS

Both supplementations resulted in reduced ratio of arachidonic acid to EPA levels. Following the EPA-rich supplementation, there was a reduction in functional activation in the left anterior cingulate cortex and an increase in activation in the right precentral gyrus coupled with a reduction in reaction times on the colour-word Stroop task. By contrast, the DHA-rich supplementation led to a significant increase in functional activation in the right precentral gyrus during the Stroop and Spatial Working Memory tasks, but there was no change in behavioural performance.

CONCLUSIONS

By extending the theory of neural efficiency to the within-subject neurocognitive effects of supplementation, we concluded that following the EPA-rich supplementation, participants' brains worked 'less hard' and achieved a better cognitive performance than prior to supplementation. Conversely, the increase in functional activation and lack of improvement in time or accuracy of cognitive performance following DHA-rich supplementation may indicate that DHA-rich supplementation is less effective than EPA-rich supplementation in enhancing neurocognitive functioning after a 30-day supplementation period in the same group of individuals.

Systematic review and meta-analysis of continuous local anaesthetic wound infiltration versus epidural analgesia for postoperative pain following abdominal surgery

BACKGROUND

Local anaesthetic wound infiltration techniques reduce opiate requirements and pain scores. Wound catheters have been introduced to increase the duration of action of local anaesthetic by continuous infusion. The aim was to compare these infiltration techniques with the current standard of epidural analgesia.

METHODS

A meta-analysis of randomized clinical trials (RCTs) evaluating wound infiltration versus epidural analgesia in abdominal surgery was performed. The primary outcome was pain score at rest after 24 h on a numerical rating scale. Secondary outcomes were pain scores at rest at 48 h, and on movement at 24 and 48 h, with subgroup analysis according to incision type and administration regimen(continuous versus bolus), opiate requirements, nausea and vomiting, urinary retention, catheter-related complications and treatment failure.

RESULTS

Nine RCTs with a total of 505 patients were included. No differences in pain scores at rest 24 h after surgery were detected between epidural and wound infiltration. There were no significant differences in pain score at rest after 48 h, or on movement at 24 or 48 h after surgery. Epidural analgesia demonstrated a non-significant a trend towards reduced pain scores on movement and reduced opiate requirements. There was a reduced incidence of urinary retention in the wound catheter group.

CONCLUSION

Within a heterogeneous group of RCTs, use of local anaesthetic wound infiltration was associated with pain scores comparable to those obtained with epidural analgesia. Further procedure-specific RCTs including broader measures of recovery are recommended to compare the overall efficacy of epidural and wound infiltration analgesic techniques.

Acute effects of different multivitamin mineral preparations with and without Guaraná on mood, cognitive performance and functional brain activation

Previous work has identified the positive effects of the acute administration of a multivitamin-guaraná preparation during an effortful executive/working memory task. Here, we aimed to differentiate the effects of multivitamins with and without guaraná and to examine the neural substrates of such effects using functional magnetic resonance imaging (fMRI). Following a double-blind, placebo-controlled, randomised, balanced crossover design, 20 participants (mean age 29 ± 5.54 years) consumed multivitamin preparations with or without guaraná (Berocca^® Performance and Boost, respectively) and a placebo. Thirty minutes post-treatment, they underwent neurocognitive assessment, consisting of a 10 min Cognitive Demand Battery, with mood ratings taken immediately before and after the battery. Five additional participants underwent post-treatment fMRI scanning during Rapid Visual Information Processing and Inspection Time activation tasks. The multivitamin with guaraná treatment was associated with significantly enhanced Serial Threes performance and self-rated contentment. fMRI revealed that both multivitamin treatments increased activation in areas associated with working memory and attentional processing, with the effect being greater in the multivitamin with guaraná condition. These data confirm the acute benefits of multivitamins with guaraná on mood and cognitive performance. Furthermore, they demonstrate for the first time increased brain activation from multivitamin preparations both with and without guaraná, as measured using fMRI.

Ly6e expression is restricted to syncytiotrophoblast cells of the mouse placenta

In the present study, we characterized the expression of lymphocyte antigen 6, locus E (Ly6e) in mouse placental trophoblast. We identified Ly6e mRNA expression in trophoblast stem (TS) cells by a gene expression screen. In vivo, Ly6e was first detectable by mRNA in situ hybridization in the chorion beginning at E8.5 with spatial expression similar to Syncytin a (Syna). At later stages of gestation, Ly6e was restricted to syncytiotrophoblast in the labyrinth. Northern blot confirmed that Ly6e was expressed in both undifferentiated and differentiated TS cell cultures but that its expression increased with differentiation. FACS analysis confirmed these results and allowed us to isolate LY6E⁺ cells, which we found to express Syna at a much higher level than did LY6E⁻ cells. Our findings suggest that LY6E is expressed in differentiated syncytiotrophoblast and may also be useful as an early marker, expressed in progenitors of this cell-type.

Negative predictive value of surveillance PET/CT in head and neck squamous cell cancer

BACKGROUND AND PURPOSE

Optimizing the utilization of surveillance PET/CT in treated HNSCC is an area of ongoing research. Our aim was to determine the negative predictive value of PET/CT in patients with treated head and neck squamous cell cancer and to determine whether negative PET/CT reduces the need for further imaging surveillance.

MATERIALS AND METHODS

We evaluated patients with treated HNSCC who underwent posttreatment surveillance PET/CT. During routine clinical readouts, scans were categorized as having negative, probably negative, probably malignant, or malignant findings. We followed patients clinically and radiographically for at least 12 months from their last PET/CT (mean, 26 months; median, 28 months; range, 12-89 months) to determine recurrence rates. All suspected recurrences underwent biopsy for confirmation.

RESULTS

Five hundred twelve patients (1553 scans) were included in the study. Two hundred fourteen patients had at least 1 PET/CT with negative findings. Of the 214 patients with a scan with negative findings, 19 (9%) eventually experienced recurrence, resulting in a NPV of 91%. In addition, a subgroup of 114 patients with 2 consecutive PET/CT examinations with negative findings within a 6-month period was identified. Only 2 recurrences were found in this group, giving a NPV of 98%.

CONCLUSIONS

In patients treated for HNSCC, a single PET/CT with negative findings carries a NPV of 91%, which is not adequate to defer further radiologic surveillance. Two consecutive PET/CT examinations with negative findings within a 6-month period, however, resulted in a NPV of 98%, which could obviate further radiologic imaging in the absence of clinical signs of recurrence.

Electrical stimulation for chronic non-specific low back pain in a working-age population: a 12-week double blinded randomized controlled trial

Background

Non-invasive electrotherapy is commonly used for treatment of chronic low back pain. Evidence for efficacy of most electrotherapy modalities is weak or lacking. This study aims to execute a high-quality, double-blinded randomized controlled clinical trial comparing 1) H-Wave® Device stimulation plus usual care with 2) transcutaneous electrical nerve stimulation (TENS) plus usual care, and 3) Sham electrotherapy plus usual care to determine comparative efficacy for treatment of chronic non-specific low back pain patients.

Methods/Design

Patients- Chronic non-specific low back pain patients between ages of 18–65 years, with pain of at least 3 months duration and minimal current 5/10 VAS pain. Patients will have no significant signs or symptoms of lumbosacral nerve impingement, malignancy, spinal stenosis, or mood disorders.

Study design- Double blind RCT with 3 arms and 38 subjects per arm. Randomization by permuted blocks of random length, stratified by Workers Compensation claim (yes vs. no), and use of opioids. The null hypothesis of this study is that there are no statistically significant differences in functional improvement between treatment types during and at the end of a 12-week week treatment period.

Data collection- Subjective data will be collected using Filemaker Pro™ database management collection tools. Objective data will be obtained through functional assessments. Data will be collected at enrollment and at 1, 4, 8, and 12 weeks for each participant by a blinded assessor.

Interventions- H-Wave® device stimulation (Intervention A) plus usual care, transcutaneous electrical nerve stimulation (TENS) (Intervention B) plus usual care, and sham electrotherapy plus usual care (control). Each treatment arm will have identical numbers of visits (4) and researcher contact time (approximately 15 hours).

Outcomes- Primary outcome measure: Oswestry Disability Index. Secondary measures include: Rowland Morris Instrument, VAS pain score, functional evaluation including strength when pushing and pulling, pain free range of motion in flexion and extension. Outcome measures assessed at baseline, 1, 4, 8, and 12 weeks. Treatment failure will be defined if patient terminates assigned treatment arm for non-efficacy or undergoes invasive procedure or other excluded cointerventions. Data will be analyzed using intention-to-treat analysis and adjusted for covariates related to LBP (e.g. age) as needed.

Discussion

Study strengths include complex randomization, treatment group allocation concealment, double blinding, controlling for co-interventions, rigorous inclusion criteria, assessment of compliance, plans for limiting dropout, identical assessment methods and timing for each treatment arm, and planned intention-to-treat analyses.

Palladium-catalyzed cross-coupling of aziridinylmetal species, generated by sulfinyl-magnesium exchange, with aryl bromides: reaction optimization, scope, and kinetic investigations

A series of novel, highly substituted N-PMP aziridines have been accessed in high yields by palladium-catalyzed cross-coupling of intact aziridines. The cross-coupling employed aryl bromides and tertiary organometallic aziridines, generated from sulfinylaziridines by sulfinyl-magnesium exchange and transmetalation to the aziridinylzinc with zinc chloride. A wide range of electron-rich and electron-poor aryl bromides were utilized to afford the functionalized aziridine products as single diastereoisomers with retention of configuration at the reacting center. Assessment of the reaction kinetics showed zero-order in both the aziridine species and the aryl bromide. This indicated that the rate-determining step was reductive elimination from the palladium(II) species bearing both the aziridine and aryl groups to form the hindered C-C bond. The intermediate aziridinylzinc species underwent a progressive, background degradation that led to a plateau in yield and afforded reduced yields in substrates with ortho-substituted aryl groups, which are less reactive due to the additional steric demands.

Brain networks subserving the evaluation of static and dynamic facial expressions

Because moving depictions of face emotion have greater ecological validity than their static counterparts, it has been suggested that still photographs may not engage 'authentic' mechanisms used to recognize facial expressions in everyday life. To date, however, no neuroimaging studies have adequately addressed the question of whether the processing of static and dynamic expressions rely upon different brain substrates. To address this, we performed an functional magnetic resonance imaging (fMRI) experiment wherein participants made emotional expression discrimination and Sex discrimination judgements to static and moving face images. Compared to Sex discrimination, Emotion discrimination was associated with widespread increased activation in regions of occipito-temporal, parietal and frontal cortex. These regions were activated both by moving and by static emotional stimuli, indicating a general role in the interpretation of emotion. However, portions of the inferior frontal gyri and supplementary/pre-supplementary motor area showed task by motion interaction. These regions were most active during emotion judgements to static faces. Our results demonstrate a common neural substrate for recognizing static and moving facial expressions, but suggest a role for the inferior frontal gyrus in supporting simulation processes that are invoked more strongly to disambiguate static emotional cues.

Abstract P1-01-13: Patterns of definitive axillary management in the era prior to reporting ACOSOG Z0011: comparison between NCCN Centers and hospitals in Michigan

Background: The results of the ACOSOG- Z0011 trial have had potential practice changing implications for the management of patients with positive sentinel lymph node (SLN) undergoing lumpectomy and radiation for breast cancer. However, some evidence suggests a shift in axillary management even prior to the initial report of data supporting sentinel lymph node biopsy (SLNB) alone in mid-2010. We analyzed data in the National Comprehensive Cancer Network (NCCN) outcomes database from NCCN centers and the Michigan Breast Oncology Quality Initiative (MiBOQI) hospitals to examine institutional practice patterns with respect to use of completion axillary dissection (CALND) for SLN positive breast cancer in the years leading up to publication of these trial results. We hypothesized that CALND would be omitted more frequently in women treated at NCCN centers compared to those treated at MiBOQI programs.

Methods: We identified 2,172 women with clinical T1/T2 N0 breast cancer who underwent breast surgery and SLNB and had a positive SLN from 2007 through 2010 at one of 12 participating NCCN centers or 12 MiBOQI sites. Patient and tumor characteristics, definitive breast procedure, year of diagnosis, and institutional affiliation were analyzed as predictors of use of SLNB alone in univariate Chi-Square and multivariable logistic regression models.

Results: CALND was omitted in 314 (14.5%) of the 2,172 patients. Over time, there was a dramatic increase in the use of SLNB alone (12% in 2007 to 23% in 2010). In the univariate analyses, increased patient age, later year of diagnosis, lower T stage, and lower pathologic N stage were significant predictors of use of SLNB alone (all p < .0001). There was no association between definitive breast surgery type, hormone receptor status, Her-2 Neu status, or institutional affiliation and use of SLNB alone. In the multivariable model, older age at diagnosis, later year of diagnosis, and lower pathologic N stage remained significant independent predictors of SLNB alone. There were no significant differences in rates of omission of CALND between NCCN and MIBOQI sites.

The disparity of priapulid, archaeopriapulid and palaeoscolecid worms in the light of new data

Priapulids and their extinct relatives, the archaeopriapulids and palaeoscolecids, are vermiform, carnivorous ecdysozoans with an armoured, extensible proboscis. These worms were an important component of marine communities during the Palaeozoic, but were especially abundant and diverse in the Cambrian. Today, they comprise just seven genera in four families. Priapulids were among the first groups used to test hypotheses concerning the morphological disparity of Cambrian fossils relative to the extant fauna. A previous study sampled at the generic level, concluding that Cambrian genera embodied marginally less morphological diversity than their extant counterparts. Here, we sample predominantly at the species level and include numerous fossils and some extant forms described in the last fifteen years. Empirical morphospaces for priapulids, archaeopriapulids and palaeoscolecids are relatively insensitive to changes in the taxon or character sample: their overall form has altered little, despite the markedly improved sampling. Cambrian and post-Cambrian genera occupy adjacent rather than broadly overlapping regions of these spaces, and Cambrian species still show lower morphological disparity than their post-Cambrian counterparts. Crucially, the significance of this difference has increased with improved taxon sampling over research time. In contrast with empirical morphospaces, the phylogeny of priapulids, archaeopriapulids and palaeoscolecids derived from morphological characters is extremely sensitive to details of taxon sampling and the manner in which characters are weighted. However, the extant Priapulidae and Halicryptidae invariably resolve as sister families, with this entire clade subsequently being sister group to the Maccabeidae. In our most inclusive trees, the extant Tubiluchidae are separated from these other living taxa by a number of small, intervening fossil clades.