Butterfly richness and abundance along a gradient of imperviousness and the importance of matrix quality.

Heterogeneity in quantity and quality of resources provided in the urban matrix may mitigate adverse effects of urbanization intensity on the structure of biotic communities. To assess this we quantified the spatial variation in butterfly richness and abundance along an impervious surface gradient using three measures of urban matrix quality: floral resource availability and origin (native vs. exotic plants), tree cover, and the occurrence of remnant habitat patches. Butterfly richness and abundance were surveyed in 100 cells (500 × 500 m), selected using a random-stratified sampling design, across a continuous gradient of imperviousness in Melbourne, Australia. Sampling occurred twice during the butterfly flight season. Occurrence data were analyzed using generalized linear models at local and mesoscales. Despite high sampling completeness, we did not detect 75% of species from the regional species pool in the urban area, suggesting that urbanization has caused a large proportion of the region's butterflies to become absent or extremely rare within Melbourne's metro-area. Those species that do remain are largely very generalist in their choice of larval host plants. Butterfly species richness and abundance declined with increasing impervious surface cover and, contrary to evidence for other taxa, there was no evidence that richness peaked at intermediate levels of urbanization. Declines in abundance appeared to be more noticeable when impervious surface cover exceeded 25%, while richness declined linearly with increasing impervious surface cover. We find evidence that the quality of the urban matrix (floral resources and remnant vegetation) influenced butterfly richness and abundance although the effects were small. Total butterfly abundance responded negatively to exotic floral abundance early in the sampling season and positively to total floral abundance later in the sampling season. Butterfly species richness increased with tree cover. Negative impacts of increased urbanization intensity on butterfly species richness and abundance may be mitigated to some extent by improving the quality of the urban matrix by enhancing tree cover and the provision of floral resources, with some evidence that native plants are more effective.

The P7C3 class of neuroprotective compounds exerts antidepressant efficacy in mice by increasing hippocampal neurogenesis.

Augmenting hippocampal neurogenesis represents a potential new strategy for treating depression. Here we test this possibility by comparing hippocampal neurogenesis in depression-prone ghrelin receptor (Ghsr)-null mice to that in wild-type littermates and by determining the antidepressant efficacy of the P7C3 class of neuroprotective compounds. Exposure of Ghsr-null mice to chronic social defeat stress (CSDS) elicits more severe depressive-like behavior than in CSDS-exposed wild-type littermates, and exposure of Ghsr-null mice to 60% caloric restriction fails to elicit antidepressant-like behavior. CSDS resulted in more severely reduced cell proliferation and survival in the ventral dentate gyrus (DG) subgranular zone of Ghsr-null mice than in that of wild-type littermates. Also, caloric restriction increased apoptosis of DG subgranular zone cells in Ghsr-null mice, although it had the opposite effect in wild-type littermates. Systemic treatment with P7C3 during CSDS increased survival of proliferating DG cells, which ultimately developed into mature (NeuN+) neurons. Notably, P7C3 exerted a potent antidepressant-like effect in Ghsr-null mice exposed to either CSDS or caloric restriction, while the more highly active analog P7C3-A20 also exerted an antidepressant-like effect in wild-type littermates. Focal ablation of hippocampal stem cells with radiation eliminated this antidepressant effect, further attributing the P7C3 class antidepressant effect to its neuroprotective properties and resultant augmentation of hippocampal neurogenesis. Finally, P7C3-A20 demonstrated greater proneurogenic efficacy than a wide spectrum of currently marketed antidepressant drugs. Taken together, our data confirm the role of aberrant hippocampal neurogenesis in the etiology of depression and suggest that the neuroprotective P7C3-compounds represent a novel strategy for treating patients with this disease.

Soil Carbon and Carbon/Nitrogen Ratio Change under Tree Canopy, Tall Grass, and Turf Grass Areas of Urban Green Space.

Soils in urban green spaces are an important carbon (C) store, but urban soils with a high carbon to nitrogen (C/N) ratio can also buffer N eutrophication from fertilizer use or atmospheric deposition. The influence of vegetation management practices on soil C cycling and C/N ratios in urban green spaces is largely unknown. In 2013, we collected replicate ( = 3) soil samples from tree canopy, tall grass, and short turf grass areas ( = 3) at four random plot locations ( = 4) established in 13 golf courses ( = 13). At each sample point, soil was separated into 0- to 0.1-, 0.1- to 0.2-, and 0.2- to 0.3-m depths (total = 1404). Linear mixed models investigated the relationships between soil properties, vegetation attributes, and green space age. Tree canopy soil was less compacted (1.07 g cm) than grassy areas (1.32 g cm). Similarly, tree canopy soil had mean C/N ratios of 17.2, as compared with between 14.2 and 15.3 in grassy areas. Soil properties in tree canopy areas were best explained by tree basal area and understory vegetation volume. Soil C/N increased with increasing understory vegetation, and the difference in soil C/N between tree canopy and short turf grass areas increased over time. The soil properties in tree canopy areas of urban green space mean they can increasingly buffer the localized use of N fertilizers and atmospheric N deposition. Managers of urban green spaces concerned about N pollution of groundwater and waterways could consider planting trees in suitable topographic locations and promoting understory vegetation and surface litter accumulation.

Randomized clinical trial of sacral versus percutaneous tibial nerve stimulation in patients with faecal incontinence.

BACKGROUND: Sacral nerve stimulation (SNS) is a well established therapy for faecal incontinence (FI). Percutaneous tibial nerve stimulation (PTNS) is a newer, less invasive, treatment. The effectiveness and acceptability of these treatments have not been compared systematically. METHODS: An investigator-blinded randomized pilot trial of PTNS versus SNS with a parallel qualitative study was performed. Quantitative clinical outcomes and qualitative data from patient interviews were collected for both interventions. RESULTS: Forty patients (39 women; mean age 59 years) met the eligibility criteria; 23 were randomized to receive SNS and 17 to PTNS. Fifteen patients progressed to permanent SNS implantation and 16 received a full course of PTNS. Within-group effect sizes were marginally greater for SNS than for PTNS on available-case analysis. Mean(s.d.) FI episodes per week at baseline, and 3 and 6 months of follow-up were: 11·4(12·0), 4·0(4·0) and 4·9(6·9) respectively for SNS compared with 10·6(11·2), 5·8(6·9) and 6·3(6·9) for PTNS. Mean(s.d.) Cleveland Clinic Incontinence Score values at baseline, and 3 and 6 months were: 16·2(3·0), 11·1(5·2) and 10·4(5·6) for SNS versus 15·1(2·7), 11·7(4·4) and 12·1(5·2) for PTNS. Improvement of at least 50 per cent in FI episodes per week at 6 months was seen in 11 of 18 patients in the SNS group compared with seven of 15 in the PTNS group. Effect estimates for SNS with chronic implanted stimulation were larger (10 of 15 patients at 6 months). Disease-specific and generic quality-of-life improvements complemented clinical outcome data. Qualitative analysis of interview data suggested that both treatments had high acceptability amongst patients. CONCLUSION: In the short term, both SNS and PTNS provide some clinical benefit to patients with FI. Registration numbers: 2010-018728-15 and 10479 (http://public.ukcrn.org.uk/search/StudyDetail.aspx?StudyID=10479).

Occupational vaccination of health care workers: uptake, attitudes and potential solutions.

OBJECTIVES: Occupational vaccination of health care workers is strongly recommended to prevent health care associated transmission but coverage in general remains suboptimal. The aim of this survey was to: 1. Estimate levels vaccination coverage for annual flu and MMR vaccines among hospital-based health care workers; 2. Explore the reasons behind low vaccination rates; and 3. Identify potential practical and policy solutions. STUDY DESIGN: A cross-sectional study. METHODS: An opportunistic survey was used to estimate MMR and flu vaccination coverage, and review attitudes and explore solutions. Staff from eight randomly selected wards, stratified by ward-level patient susceptibility, were invited to participate. RESULTS: In total 133 staff responded, an approximate response rate of 68%. Seventy one percent had ever received an MMR and 42% had received the most recent flu vaccination. Actively declining vaccination was more common for flu than MMR (29% and 7% respectively). Side-effects, insufficient knowledge and vaccine ineffectiveness were popular justifications for declining flu vaccination but not MMR. Not seeing vaccination as a professional responsibility was associated with declining flu vaccination (P < 0.001). Improving vaccination coverage with booster vaccines for new staff and immunity testing received strong support from staff working with vulnerable groups (82% and 74% respectively); 70% of this staff group also supported compulsory vaccination. CONCLUSIONS: Improving staff education may increase coverage. Clarification of the benefits of vaccination in specific staff groups may also improve uptake. Routine booster vaccinations and immunity testing were generally acceptable and compulsory vaccination of certain staff groups warrants further investigation.

Clinical and psychosocial functioning in adolescents and young adults with anorectal malformations and chronic idiopathic constipation.

BACKGROUND: Faecal incontinence (FI) and constipation occur following corrective surgery for anorectal malformations (ARMs) and in children or adults with chronic constipation without a structural birth anomaly (chronic idiopathic constipation, CIC). Such symptoms may have profound effects on quality of life (QoL). This study systematically determined the burden of FI and constipation in these patients in adolescence and early adulthood, and their effect on QoL and psychosocial functioning in comparison with controls. METHODS: Patients with ARMs or CIC were compared with age- and sex-matched controls who had undergone appendicectomy more than 1 year previously and had no ongoing gastrointestinal symptoms. Constipation and FI were evaluated using validated Knowles-Eccersley-Scott Symptom (KESS) and Vaizey scores respectively. Standardized QoL and psychometric tests were performed in all groups. RESULTS: The study included 49 patients with ARMs (30 male, aged 11-28 years), 45 with CIC (32 male, aged 11-30 years) and 39 controls (21 male, aged 11-30 years). The frequency of severe constipation among patients with ARMs was approximately half that seen in the CIC group (19 of 49 versus 31 of 45); however, frequencies of incontinence were similar (22 of 49 versus 21 of 45) (P < 0·001 versus controls for both symptoms). Physical and mental well-being were significantly reduced in both ARM and CIC groups compared with controls (P = 0·001 and P = 0·015 respectively), with generally worse scores among patients with CIC. Both were predicted by gastrointestinal symptom burden (P < 0·001). There were no statistically significant differences in state or trait psychiatric morbidity between groups. CONCLUSION: FI and constipation are major determinants of poor QoL in adolescents and young adults with ARMs and in those with CIC.

The effects of age and childbirth on anal sphincter function and morphology in 999 symptomatic female patients with colorectal dysfunction.

BACKGROUND AND OBJECTIVES: Conflicting data exist on the contributions of advancing age and childbirth on the structure and function of the anal sphincter. This study aimed to examine the relative contributions of age and childbirth in a large cohort of women referred for investigation of symptoms of colorectal dysfunction (fecal incontinence and constipation). SETTING: This study was conducted at a specialist surgical colorectal investigation unit in a university teaching hospital. PATIENTS: Retrospective analysis was performed on prospectively collected demographic, symptom profile, and physiologic data from 3686 female patients. Strict exclusion criteria were applied, leaving 999 patients for univariate, multivariate, and logistic statistical modeling. MAIN OUTCOME MEASURES: The effects of independent variables alone and in combination on anal sphincter pressures (resting and squeeze increment) and the presence of sphincter defects (internal and external) were expressed as regression coefficients and odds ratios. RESULTS: Median age was 42 years (range, 16-88), and parity was 2 (range, 0-11); 16% were nulliparous. Three hundred sixty patients had fecal incontinence, 352 had constipation, and 287 had combined symptoms. Anal resting tone decreased with age by 0.66 cm H2O per year, and by 4.3 cm H2O per birth, and was associated with both internal and external anal sphincter defects (p = 0.0001 for both). Squeeze increment pressures decreased by 0.3 cm H2O per year, and by 3.8 cm H2O per birth; decreased pressures were, however, only significantly associated with external anal sphincter defects (p = 0.0001) as a result of childbirth. Cesarean delivery was protective against both reduced anal pressures and sphincter defects. Pudendal nerve terminal motor latencies increased bilaterally with age and with vaginal delivery; the impact of both was greater on the left nerve. Rectal sensation was unaffected by age or parity. CONCLUSIONS: Aging predominantly affects anal resting pressures; childbirth, particularly instrumental delivery, is detrimental to the structure and function of the external sphincter.

Management of idiopathic anal fistula using cross-linked collagen: a prospective phase 1 study.

AIM: Fibrin glue and porcine intestinal submucosa are used in novel sphincter-preserving techniques to heal anal fistulae. However, their success is highly variable and decreases with the length of follow up. The aim of this study was to assess the safety, feasibility and potential efficacy of another novel agent, cross-linked collagen, in two different physical formats, to heal anal fistulae. METHOD: Prospectively recruited patients underwent symptom, continence and anal physiology assessments and magnetic resonance imaging. Patients with secondary tracts or acute sepsis were excluded. At operation, participants were randomized to receiving a solid collagen implant or collagen fibres suspended in fibrin glue. Follow up included repeat symptom, continence and physiological assessments at 3 months, and regular clinical review thereafter. RESULTS: Twenty-nine of 43 entrants were eligible for inclusion. Thirteen patients received the collagen implant, and 16 collagen-fibrin glue. Three months postoperation, no patient experienced acute sepsis or continence disturbance, and sphincter function and integrity were unchanged. At 29 months, 12 of 15 (one lost to follow up) patients treated with collagen-fibrin glue were healed, compared with seven of 13 who received the implant. CONCLUSION: In the short-to-medium term, both techniques are safe and equally effective. The results justify continued research into the use of biomaterials to heal anal fistulae.

Combined vertical reduction rectoplasty and sacral nerve stimulation for rectal evacuatory dysfunction and faecal incontinence associated with previous anorectal malformation.

Functional outcomes following surgery for anorectal malformation are variable, with many children experiencing persisting anorectal dysfunction. We describe a 34-year-old female with previous vestibular fistula who experienced lifelong rectal evacuatory dysfunction and faecal incontinence; she was treated in a two stage process producing efficient defecation and almost total continence.

Generation of lytic natural killer 1.1+, Ly-49- cells from multipotential murine bone marrow progenitors in a stroma-free culture: definition of cytokine requirements and developmental intermediates.

We have developed a stroma-free culture system in which mouse marrow or thymus cells, known to be enriched for lymphoid progenitors, can be driven to generate natural killer (NK) cells. Culture of lineage marker (Lin)-, c-kit+, Sca2+, interleukin (IL)-2/15Rbeta (CD122)- marrow cells in IL-6, IL-7, stem cell factor (SCF), and flt3 ligand (flt3-L) for 5-6 d followed by IL-15 alone for an additional 4-5 d expanded the starting population 30-40-fold and gave rise to a virtually pure population of NK1.1+, CD3- cells. Preculture in IL-6, IL-7, SCF, and flt3-L was necessary for inducing IL-15 responsiveness in the progenitors because the cells failed to significantly expand when cultured in IL-15 alone from the outset. Although culture of the sorted progenitors in IL-6, IL-7, SCF, and flt3-L for the entire 9-11-d culture period caused significant expansion, no lytic NK1.1+ cells were generated if IL-15 was not added, demonstrating a critical role for IL-15 in NK differentiation. Thus, two distinct populations of NK progenitors, IL-15 unresponsive and IL-15 responsive, have been defined. Similar results were obtained with Lin-, CD44+, CD25-, c-kit+ lymphoid progenitors obtained from adult thymus. The NK cells generated by this protocol lysed the NK-sensitive target YAC-1 and expressed markers of mature NK cells with the notable absence of Ly-49 major histocompatibility complex (MHC) receptors. However, despite the apparent lack of these inhibitory MHC receptors, the NK cells generated could distinguish MHC class I+ from class I- syngeneic targets, suggesting the existence of novel class I receptors.

Importance of extrasphincteric mechanisms in the pathophysiology of faecal incontinence in adults with a history of anorectal anomaly.

BACKGROUND: Although surgery for congenital anorectal anomalies (ARAs) aims to preserve anorectal function, faecal incontinence and constipation often result. Apart from the anal sphincters, continence is dependent on multiple anatomical and physiological factors. The aim of this study was to evaluate adults with a history of ARA to determine the role of such factors in functional outcome. METHODS: The study included 20 consecutive adult patients with faecal incontinence who had undergone anorectal surgery as infants. Comprehensive testing included anal manometry, endoanal ultrasonography, tests of pudendal nerve function and rectal sensory function, evacuation proctography and colonic transit studies. RESULTS: Anal resting tone and squeeze increments were both attenuated in 15 of 19 patients. Integrity of the internal and external anal sphincters was compromised in 16 and 15 of 18 patients respectively. Eleven of 13 had evidence of pudendal neuropathy. Rectal sensation was abnormal in 14 of 18 patients, of whom ten were hypersensitive and four hyposensitive. Rectal evacuation was abnormal in nine of 14. Colonic transit was delayed in five of eight patients with constipation. CONCLUSION: Faecal incontinence in adult patients with ARA is related to various pathophysiologies. Structural integrity of the anal sphincters is a major factor, but extrasphincteric mechanisms, notably rectal sensory function, may be as important.

Human in vivo cellular response to a cross-linked acellular collagen implant.

BACKGROUND: Hernia surgery, in particular parastomal hernia mesh repair and new techniques for hernia prevention, require novel biomaterials that avoid fibrosis and potential bowel erosion, while retaining adequate strength for their intended purpose. The aim was to evaluate the human host response to an acellular porcine-derived cross-linked collagen implant. METHODS: In a prospective pilot study on prevention of parastomal herniation, 15 patients undergoing loop stoma formation had an implant placed within the anterior abdominal wall. Histopathology and immunohistochemistry were performed to analyse the implant qualitatively and, where appropriate, quantitatively for biocompatibility, degradation, cellular infiltration, neo-extracellular matrix (ECM) formation and neovascularization. RESULTS: At a median of 7 (range 1-8) months, 12 of 15 patients had stoma reversal and 11 implant biopsies were obtained. In biopsies from ten of the 11 patients all responses were limited to the periphery of the implant and native pores. There was a minimal inflammatory response and minimal degradation of the implant. Fibroblastic and neovascular infiltration were noted, as was matrix metalloproteinase 1 activity with organized deposition of host collagen, fibronectin and laminin. CONCLUSION: The collagen implant demonstrated excellent biocompatibility and resistance to degradation in most patients. However, fibrovascular in-growth and ECM deposition were limited. This implant has excellent potential for soft tissue reinforcement.

Normalization of substance P levels in rectal mucosa of patients with faecal incontinence treated successfully by sacral nerve stimulation.

BACKGROUND: Sacral nerve stimulation (SNS) may improve faecal incontinence by modulating rectal sensation. This study measured changes in the peripheral expression of various neural epitopes in response to SNS. METHODS: Rectal mucosal biopsies were taken from 12 patients before and after temporary SNS, and from ten responders at 90 days after permanent stimulation. Sections were immunostained for substance P, transient receptor potential vanilloid (TRPV) 1, vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP). Levels were compared with those in nine continent controls. RESULTS: Baseline levels of percentage area immunoreactivities of substance P (median 0.51 (95 per cent confidence interval 0.31 to 0.73) versus 0.13 (0.07 to 0.27) per cent; P < 0.001) and TRPV1 (0.76 (0.41 to 1.11) versus 0.09 (0.04 to 0.14) per cent; P < 0.001), but not of VIP (1.26 (0.37 to 2.15) versus 1.28 (0.39 to 2.17); P = 0.943), were significantly greater than in controls. Successful SNS resulted in a significant decrease in substance P immunostaining after temporary (0.15 (0.06 to 0.51) per cent; P = 0.051) and permanent (0.17 (0 to 0.46) per cent; P = 0.051) stimulation. Immunoreactivity of TRPV1, VIP, CGRP and neural markers showed no qualitative change. CONCLUSION: Patients with faecal incontinence demonstrate normalization of raised rectal mucosal substance P levels following successful SNS.

Parastomal hernia prevention using a novel collagen implant: a randomised controlled phase 1 study.

BACKGROUND: Parastomal hernias can be prevented or repaired using synthetic mesh; however, reported complications include infection, fibrosis and potential bowel erosion. The study aim was to assess the safety, feasibility and potential efficacy of using a prophylactic collagen implant. METHODS: Twenty patients undergoing defunctioning stomas were randomised to a conventional procedure or reinforcement with the implant. Follow-up included regular symptom questionnaires, clinical examination, stoma site ultrasound, and serum inflammatory markers. RESULTS: Ten patients (four males; mean BMI 26.3) had a conventional stoma, and ten (three males; mean BMI 26.3) received the implant. At a median of 6.5 months follow-up, a parastomal hernia was clinically evident in three of ten patients without the implant, and in none of ten patients with the implant. There were no clinical complications, ultrasound evidence of chronic seromas or serological evidence of a systemic inflammatory response. CONCLUSIONS: Xenogeneic collagen has been demonstrated to aid soft tissue reinforcement. In this study, in contrast to published data relating to the use of conventional synthetic mesh, there were no complications related to infection or the implant's proximity to the bowel. This trial demonstrates that the implant is safe, feasible to use and has the potential to prevent parastomal herniation.

A case-controlled pilot study assessing the safety and efficacy of the Stapled Mesh stomA Reinforcement Technique (SMART) in reducing the incidence of parastomal herniation.

BACKGROUND: Parastomal hernias (PH) are frequent with a high morbidity. Three randomised controlled trials have shown that prophylactic mesh stoma reinforcement significantly reduces their incidence. Implantation and fixation of mesh can be time-consuming, difficult to perform laparoscopically and does not deal with the excessive stretching of the trephine and the creation of an oversized defect. The Stapled Mesh stomA Reinforcement Technique (SMART) obviates these technical problems. The aim of this study was to assess the safety and efficacy of a novel surgical technique called SMART in preventing parastomal herniation. METHOD: SMART uses a purpose designed circular stapling gun (Compact™, Frankenman International Limited) of various diameters to create a precise trephine and simultaneously fixes a mesh sub-peritoneally and circumferentially to the trephine. Recruited patients were deemed to be high risk for parastomal herniation and randomisation in a controlled trial was contraindicated. Incidence of parastomal related symptoms and recurrences were documented at clinic visits and radiological confirmation of recurrences, when available, was used for final analysis. A control group of patients who underwent stoma resiting without mesh reinforcement for parastomal herniation was used for comparative purposes. RESULTS: 22 patients (16 F:6 M, mean age 49 ± 16 years, BMI 33.0 ± 7.0) underwent SMART (18 open, 4 laparoscopic). There were no intra-operative or early stoma complications. During a median FU of 21 months (range 12-24), four patients (19%) were diagnosed with recurrent parastomal herniation, one of which required re-operation. The parastomal herniation rate (73%) in the control group (6 F:5 M) was significantly higher (p = 0.003) although patients had similar age (59 ± 15 years, p = 0.1) and body-mass index (29.0 ± 3.0, p = 0.1). CONCLUSION: SMART is a new and simple technique of precisely creating a reinforced stoma trephine at both open and laparoscopic surgery. It obviates the technical disadvantages of traditional stoma formation. This pilot study, in a selected group of patients at high risk for parastomal herniation, indicates that the procedure is clinically safe but randomised controlled trials are required to determine its efficacy in reducing parastomal herniation in all patients undergoing elective stoma formation.

Pharmacologic rescue of motor and sensory function by the neuroprotective compound P7C3 following neonatal nerve injury.

Nerve injuries cause pain, paralysis and numbness that can lead to major disability, and newborns often sustain nerve injuries during delivery that result in lifelong impairment. Without a pharmacologic agent to enhance functional recovery from these injuries, clinicians rely solely on surgery and rehabilitation to treat patients. Unfortunately, patient outcomes remain poor despite application of the most advanced microsurgical and rehabilitative techniques. We hypothesized that the detrimental effects of traumatic neonatal nerve injury could be mitigated with pharmacologic neuroprotection, and tested whether the novel neuroprotective agent P7C3 would block peripheral neuron cell death and enhance functional recovery in a rat neonatal nerve injury model. Administration of P7C3 after sciatic nerve crush injury doubled motor and sensory neuron survival, and also promoted axon regeneration in a dose-dependent manner. Treatment with P7C3 also enhanced behavioral and muscle functional recovery, and reversed pathological mobilization of spinal microglia after injury. Our findings suggest that the P7C3 family of neuroprotective compounds may provide a basis for the development of a new neuroprotective drug to enhance recovery following peripheral nerve injury.

Intra-operative activation of coagulation--a stimulus to thrombosis mediated by vasopressin?

Vasopressin infusions in normal volunteers that produce concentrations in plasma comparable to those seen during stress, cause an increase in plasma factor VIII and shortening of the euglobulin clot lysis time (ECLT). We have investigated the relationship between endogenous vasopressin (aVP) release and haemostatic function in 7 patients undergoing major abdominal surgery. Blood samples were taken at nine intervals during the operative procedure. Plasma aVP levels peaked at median values of 51 pg/ml during bowel manipulation and remained elevated on the first post-operative day. Following, and in close temporal relationship with the rise in aVP there were increases in factor VIII coagulant activity, the ristocetin co-factor, von Willebrand antigen, plasminogen activator activity (10(6)/ECLT2) and fibrinopeptide A concentrations with shortening of the activated partial thromboplastin time. The relationship was similar to that seen following infusion of aVP in human volunteers. The results are consistent with the hypothesis that aVP is an important mediator of changes in haemostatic function which accompany stress and might contribute to the thrombotic risk associated with surgical operations.