Non-invasive ventilation for people with neuromuscular disorders in Australia and New Zealand: a qualitative study of clinician perspectives

OBJECTIVES

To explore the experiences of Australian and New Zealand clinicians with respect to care pathways, their awareness and use of non-invasive ventilation guidelines, and their perspectives on delivering quality non-invasive ventilation services to people with neuromuscular disorders.

DESIGN, SETTING, PARTICIPANTS

Qualitative study; semi-structured focus groups and individual interviews with Australian and New Zealand clinicians who provide non-invasive ventilation services to people with neuromuscular disorders, recruited from participants at a 2017 sleep medicine conference. Interviews were conducted during 1 October 2017 - 31 May 2018.

MAIN OUTCOME MEASURES

Major themes identified by an iterative, semantic, and inductive analysis.

RESULTS

A total of 28 participants attended the four focus group sessions and five individual interviews; fourteen each from New Zealand and Australia, seventeen women and eleven men, eighteen physicians and ten other clinicians. Two major themes were identified: decision making for current practice, and resource constraints. Participants noted variable use of clinical guidelines and limited training to meet the needs of people with neuromuscular disorders who require non-invasive ventilation. They described a lack of dedicated funding, unstructured care pathways, equipment supply levels that do not meet need, low staff-to-patient ratios and staff shortages, and the inability to deliver quality multidisciplinary care. The need for clinical guidelines and service specifications was highlighted as requisite for reducing variation in clinical care.

CONCLUSIONS

Systemic factors influence the needs-based provision of non-invasive ventilation for people with neuromuscular disorders. Development of clinical guidelines for Australia and New Zealand, dedicated funding for respiratory services for people with neuromuscular disorders, and specialist clinician training are important for equitable and high quality non-invasive ventilation care.

Health System Factors Affecting the Experience of Non-Invasive Ventilation Provision of People with Neuromuscular Disorders in New Zealand

Non-invasive ventilation (NIV) is a critical therapy for many patients with neuromuscular disorders (NMD), supporting those with respiratory failure to achieve adequate respiration and improve their quality of life. The aim of this study was to explore the experiences of access to, consent, uptake, maintenance and safe use of non-invasive ventilation by people with NMD. Semi-structured individual interviews were conducted with 11 people with NMD, each using NIV for more than 12 months. A critical realism ontological paradigm with contextualism epistemology guided the Reflexive Thematic Analysis. An Equity of Health Care Framework underpinned the analysis. Three themes were interpreted: Uptake and informed consent for NIV therapy; Practicalities of NIV; and Patient-clinician relationships. We identified issues at the system, organization and health professional levels. Conclusions: We recommend the development of national service specifications with clear standards and dedicated funding for patients with NMD and call on the New Zealand Ministry of Health to proactively investigate and monitor the variations in service delivery identified. The specific areas of concern for patients with NMD suggest the need for NMD-related NIV research and service provision responsive to the distinct needs of this population.

"Me and 'that' machine": the lived experiences of people with neuromuscular disorders using non-invasive ventilation

PURPOSE

Neuromuscular disorders (NMD) encompasses a wide range of conditions, with respiratory weakness a common feature. Respiratory care can involve non-invasive ventilation (NIV) resulting in fewer hospital admissions, a lower mortality rate and improved quality of life. The aim of this study was to explore the 'lived experience' of NIV by people with NMD.

METHODS

Interpretive Phenomenological Analysis (IPA) with semi-structured, face to face interviews with 11 people with NMD, using bi-level positive airway pressure for NIV for more than 12 months.

RESULTS

Three themes were interpreted: (i) Alive, with a life; (ii) Me and 'that' machine; and (iii) Precariousness of this life. NIV enabled hope, independence and the opportunity to explore previously perceived unattainable life experiences. Yet, participants felt dependent on the machine. Furthermore, practical considerations and fear of NIV failure created a sense of precariousness to life and a reframing of personal identity.

CONCLUSION

The findings highlight the broad ranging positive and negative effects that may occur for people with NMD when using this important therapy. Ongoing non-judgemental support and empathy are required from health professionals as the use of NIV challenged concepts such as 'living life well' for people with NMD. IMPLICATIONS FOR REHABILITATIONNeuromuscular disorders may result in respiratory weakness requiring non-invasive ventilation (NIV).When prescribed early, NIV can results in fewer hospital admissions, a lower mortality rate and improved quality of life.The relationship of people with NMD with their NIV machine is complex and impacts on and requires adjustment to their identity.NIV users acknowledged that NIV provided hope but simultaneously recognised the precariousness of NIV on their life.In order to better support people with NMD healthcare professionals need to better understand how the physical, psychological and social implications of NIV affect an individual's life.

iSelf-Help: a co-designed, culturally appropriate, online pain management programme in Aotearoa

INTRODUCTION

Current best practice recommends group-based pain management programmes for long-term improvements in persistent pain-related disability. However, there are barriers for people to access in-person delivered pain management programmes in Aotearoa.

AIMS

To develop a co-designed, culturally responsive, online group-based pain management programme (iSelf-help) for people with persistent pain.

METHODS

A modified participatory action research (PAR) framework was used to co-design contents and cultural-appropriateness of iSelf-help. The PAR team included: (1) seven end-users living with persistent pain, who had previously attended an in-person delivered group pain management programme, (2) two pain management clinicians, (3) two health researchers, (4) two digital health experts, and (5) a health literacy expert. Five meetings were held with the PAR group and a Nominal Group Technique was used to rank order the preferred features of content delivery. In parallel, to ensure cultural appropriateness of iSelf-help, three focus groups (n = 15) were held with Māori (the Indigenous population of Aotearoa) living with persistent pain in collaboration with a Māori community health trust. All contents were reviewed by a Māori Health literacy expert and core contents were translated into Te Reo (Māori language). All contents were finalised by iterative discussion among the PAR team and consultation with Māori stakeholders. The preliminary version of iSelf-help was pilot tested with the PAR group participants and Māori community members living with persistent pain and their feedback was included. The iterative co-design process occurred over a period of nine months.

RESULTS

The finalised version of iSelf-help included a total of 130 resources organised in to 12 content relevant online modules plus a dedicated welcoming page and an online community forum. Each module included: short videos, animations explaining main concepts, patient stories, written content to accompany visual content, podcasts of relaxation techniques, illustrated texts, and evidence-summaries. A dedicated module of videos demonstrating cardiovascular and strengthening exercises of varying intensity was also included.

CONCLUSIONS

This is the first co-created, culturally appropriate, on-line group pain management programme for people with persistent pain, developed in Aotearoa. The next step is to evaluate the clinical and cost-effectiveness of iSelf-help compared to in-person delivered pain management programme.

'I think there is nothing . . . that is really comprehensive': healthcare professionals' views on recommending online resources for pain self-management

Objectives

To explore healthcare professionals' views on, and attitudes, towards recommending online resources for persistent pain self-management.

Methods

This study was the qualitative phase of a two-phase mixed method study. Thirty-one New Zealand health professionals involved in the management of persistent pain were interviewed via focus groups and individual interviews. Data were analysed using the general inductive approach.

Results

The major themes were as follows: (1) risks and limits of online information outweigh benefits, (2) a blended model, of online resources with healthcare professional support, could work, (3) only trustworthy resources can be recommended, (4) need for personalisation and (5) perceived barriers to adoption.

Conclusion

Online resources were perceived as a useful adjunct to support pain self-management; however, due to potential risks of misinterpretation and misinformation, healthcare professionals proposed a 'blended model' where curated online resources introduced during face-to-face consultations could be used to support self-management. Participants needed 'trustworthy online resources' that provide evidence-based, updated information that is personalised to clients' health literacy and cultural beliefs.

Practice implications

Training for healthcare professionals on critical appraisal of online resources or curation of evidence-based online resources could increase recommendation of online resources to support pain self-management as an adjunct to in-person care.

"A coalition of the willing": experiences of co-designing an online pain management programme (iSelf-help) for people with persistent pain

BACKGROUND

Participatory approaches to developing health interventions with end-users are recommended to improve uptake and use. We aimed to explore the experiences of co-designing an online-delivered pain management programme (iSelf-help) for people with persistent pain.

METHODS

A modified participatory action research (PAR) framework was used to co-design contents and delivery of iSelf-help. The PAR team included: (1) a patient advisory group consisting of people living with persistent pain (n = 8), (2) pain management service clinicians (n = 2), (3) health researchers (n = 3), (4) digital health experts (n = 2), (5) a health literacy expert, and (6) two Māori health researchers and our community partner who led the cultural appropriateness of iSelf-help for Māori (the Indigenous population of New Zealand). The iSelf-help co-design processes and activities of the 'PAR' team is reported in another paper. In this paper, all PAR team members were invited to share their experiences of the co-design process. Individual interviews were held with 12 PAR team members. Interview transcripts were analysed using the General Inductive Approach.

RESULTS

Five common themes were identified from the interviews: (1) Shared understanding and values of the co-design process, (2) Mismatched expectations with content creation, (3) Flexibility to share power and decision making, (4) Common thread of knowledge, and (5) Shared determination. Sustaining these themes was an overarching theme of "A coalition of the willing".

CONCLUSIONS

PAR team members valued the shared determination and responsibility to co-design iSelf-help. They also acknowledged the complexities and challenges during the process related to mismatched expectations, power sharing and establishing a common thread of knowledge. Successful co-design requires a shared commitment and responsibility as a coalition to meet the aspirations of end-users, within the boundaries of time and budget.

Do pain management websites foster self-management support for people with persistent pain? A scoping review

OBJECTIVES

To evaluate if the contents of pain management websites include the current best practice self-management support strategies for people with persistent pain, are cultural tailored and to determine the website quality.

METHODS

Websites were searched from three major search engines (Google, Bing, and Yahoo). Websites providing information on self-management strategies and websites that were freely available to the public were included. The website contents were evaluated using a 14-item self-management support (SMS-14) checklist. Website quality was assessed using the Health On the Net code (HONcode) certification.

RESULTS

Of the twenty-seven websites evaluated, the websites scored a median of nine items (range 1-13) from the SMS-14 checklist. The websites LivePlanBe, ACI Pain Management Network and MyJointPain top-scored (13/14) from the SMS-14 checklist. One website (ACI Pain Management Network) provided culturally tailored information and HONcode certification was present in six websites.

CONCLUSIONS

The review identified 27 contemporary pain management websites that could be used for self-management skills training.

PRACTICE IMPLICATIONS

Clinicians could refer people with persistent pain to top ranked websites - LivePlanBe, ACI Pain Management Network, and MyJointPain for enabling self-management skills, with the caveats that most websites lacked cultural tailoring, and have limited or no evidence of clinical efficacy.

Current practices of health care providers in recommending online resources for chronic pain self-management

Purpose

Online health resources (websites, apps and social media) may be an adjunct to provide self-management support for people with persistent or chronic pain. Endorsement of online health resources by health care providers is crucial for uptake by end-users. The aim of this study was to investigate the current practices of New Zealand (NZ) health care providers in recommending online resources for persistent pain management, and to identify what factors predict health care providers’ recommendations and to explore the common concerns.

Methods

An online survey of NZ health care providers (ie, chiropractors, general practitioners, nurses, occupational therapists, osteopaths, physiotherapists, psychologists, specialist consultants, and social workers) involved in the management of persistent pain was conducted. The recruitment strategy was tailored to each occupation via occupation-specific professional organizations, and by approaching multidisciplinary professional organizations.

Results

Data from 213 health care providers were used in the final analysis. Most of the health care providers were physiotherapists (n=71), followed by chiropractors (n=39) and general practitioners (n=31). Fifty three percent (111/210) of health care providers reported currently recommending online resources. A multivariate logistic regression model showed that specialist interest in treating pain (OR=3.84; 95% CI: 1.66, 8.87; P=0.002), and level of confidence in recommending online resources (OR=1.05; CI: 1.04, 1.07; P<0.001), positively influenced recommending online resources. The majority of the health care providers (65%, 138/213) were concerned about the safety issues related to the risk of patients misinterpreting online information and to the lack of evidence-based information.

Conclusion

Half of the health care providers surveyed reported recommending online resources, which may suggest limited confidence in recommending, or knowledge of, existing online resources for persistent pain management. Ongoing education for health care providers on evidence-based online resources is required to recommend online resources as a self-management support tool for people with persistent pain.

User perspective on receiving adaptive equipment after stroke: A mixed-methods study

BACKGROUND.

Adaptive equipment (AE) is frequently provided during stroke rehabilitation by occupational therapists.

PURPOSE.

This study aimed to identify the AE that people typically use after a stroke and the outcomes achieved as a result, and to explore people's experiences obtaining and using AE, to inform both practice and policy in this field.

METHOD.

A mixed-methods study, involving a postal questionnaire and interviews, used descriptive statistics and grounded theory to analyze the quantitative and qualitative data, respectively.

FINDINGS.

Questionnaire data ( n = 258) revealed mobility AE was issued most frequently, with increased safety as the primary reported outcome. Interview data ( n = 15) indicated relationships with health professionals and the hospital environment shaped early AE selection and use. Once home, making sense of AE and community participation were more influential.

IMPLICATIONS.

Therapeutic relationships and reflection time are critical to maximize AE use after stroke. Policy and related funding for AE need to prioritize community participation.

Park-based physical activity interventions for persons with disabilities: A mixed-methods systematic review

BACKGROUND

Park-based physical activity (PA) interventions improve health in the general population, but it is unknown if the evidence can be translated to persons with disabilities.

OBJECTIVES

To conduct a mixed-methods systematic synthesis of the evidence for park-based physical activity interventions for persons with disabilities and secondarily, to consider the health benefits across the lifespan (children and adolescents, young, middle, and older adults).

METHODS

All major electronic databases were searched from inception until 30^th November 2016. Studies were eligible if the PA intervention was conducted in an urban park environment with people reporting a disability (e.g. physical, psychological and developmental impairments) and health outcomes were evaluated with biopsychosocial measures. Methodological quality was assessed using Crowes Critical Appraisal Tool (CCAT) and key findings extracted.

RESULTS

Six quantitative and four qualitative papers, comprising of 446 participants (age range seven to ninety-one years), were included for qualitative synthesis; five in children/adolescents, none in adults, and five in older adults. There was limited, low level, preliminary evidence for short-term improvements in physical, psychological, and social health outcomes in children and older adults with disabilities as well as improvements in disability-related impairments. When accessible, parks fostered societal inclusion.

CONCLUSIONS

Health benefits from park use in persons with disabilities were identified. Parks may provide an alternative environment for rehabilitation and management of disabilities. Further randomized controlled trials evaluating the long-term effectiveness of park-based interventions is necessary to corroborate our findings. Legislative commitment ensuring urban parks are accessible may mitigate some health disparities in persons with disabilities.

What Works and Does Not Work in a Self-Management Intervention for People With Chronic Pain? Qualitative Systematic Review and Meta-Synthesis

BACKGROUND

Self-management interventions fostering self-efficacy improve the well-being of people with chronic pain.

PURPOSE

The purpose of this study was to synthesize the enablers (what works) and barriers (what does not) of incorporating self-management strategies for people in everyday life after completion of a pain self-management intervention.

DATA SOURCES

Major electronic databases (MEDLINE, AMED, PsycINFO, Cochrane Library, PubMed, CINAHL, Scopus, and Google Scholar) were searched from inception to July 2016.

STUDY SELECTION

Study selection included qualitative and mixed-method studies that explored the perceptions of individuals with chronic pain after completion of a self-management intervention.

DATA EXTRACTION

A thematic analysis approach was used to synthesize the review findings, and a Confidence in the Evidence from Reviews of Qualitative Research (CERQual) Approach was used to assess the level of confidence.

DATA SYNTHESIS

Thirty-three studies with 512 participants were included. Enablers to self-management included self-discovery-the ability to distinguish self (ie, body, thoughts, and feelings) from pain; feeling empowered by incorporating self-management strategies into practice; and supportive ambience via collaborative relationships with clinicians and support from family and friends. Barriers to self-management included difficulty with sustaining motivation for pain self-management; distress experienced from ongoing pain, anxiety, and depression; and unsupportive relationships with clinicians, family, and friends.

LIMITATIONS

This review only included interventions that involved at least 4 self-management skills; thus, informative studies may have been missed. The follow-up period varied from immediately after the intervention to 72 months following the intervention; therefore, it is uncertain which of the key enablers and barriers were most influential long term. Only articles published in the English language were included; studies conducted in low- and middle-income countries could not be located.

CONCLUSIONS

The sustained effort to self-manage chronic pain could be exhausting, and motivation could wane over time following intervention. Providing intermittent support in the form of booster sessions and peer support groups may be important. Person-centered care via shared decision making and guided problem solving is essential to facilitating ongoing self-management.

Accessibility and usability of parks and playgrounds

BACKGROUND

Public parks and playgrounds are an environment for leisure activity, which all generations can enjoy at low or no financial cost. Evaluating the accessibility and usability of parks and playgrounds is crucial because their design, environment (natural and built) and safety could restrict participation of persons with disabilities.

OBJECTIVE

To evaluate the accessibility and usability of 21 public parks and playgrounds in three metropolitan cities of New Zealand. Secondary aims were to compare the accessibility and usability by park type (destination or neighborhood) and deprivation level (high and low).

METHODS

Twenty-one parks were evaluated. A stratified random sampling was used to select 18 parks (six from each city). Three additional parks were purposely selected (one from each city) at the request of each respective city council. The parks and playgrounds were evaluated using a customized tool. Data were analyzed using descriptive statistics.

RESULTS

None of the parks we evaluated met the national standards and/or international guidelines for park and playground design. We identified potential accessibility and usability issues with car parking spaces, path surfaces and play equipment as well as lack of lighting and fencing. The presence of amenities (e.g. toilets and drinking fountains) was more common in destination parks. Fewer parks in areas of higher deprivation had accessible car parking spaces and main paths wider than 1.5 m.

CONCLUSION

Our evaluation identified potential design, environmental and safety barriers to park and playground based participation for persons with disabilities across the lifespan. A larger, more comprehensive evaluation of parks and playgrounds is required.

"Not always a straight path": patients' perspectives following anterior cruciate ligament rupture and reconstruction

PURPOSE

To explore patients' perspectives following anterior cruciate ligament rupture and subsequent reconstructive surgery.

METHODS

A qualitative study design was employed, using validated questionnaires, interviews and general inductive methodology. Semi-structured interviews were conducted with five men and four women who had undergone an anterior cruciate ligament reconstruction in the past 6-36 months. Participants completed the Knee Osteoarthritis Outcome Score and the Tegner Activity Score. Descriptive statistics were used to analyze quantitative data. Interviews were recorded, transcribed and analyzed using the general inductive approach to develop key themes.

RESULTS

Participants had not returned to pre-injury knee-related activity levels (Tegner score: 7 pre-injury; 4 current). The theme of a disruptive "journey" emerged with two sub-themes of "loss of identity" and "life at the present," influenced positively and negatively by "support systems" and experience with the "care pathway." This unequivocally negative experience resulted in irrevocable changes to their lives, reflected by current lower knee-related quality of life.

CONCLUSIONS

Anterior cruciate ligament injury and rehabilitation thereof have a profound influence in the individual's identity. The results imply that a broader approach is needed within the rehabilitation process to address psychosocial factors, in addition to physical impairments and function. Implications for rehabilitation Anterior cruciate ligament rupture has a profound influence on patients' understanding of their individual identity. Support systems the patients have in place influence the patients' experience of the care pathway. Understanding psychosocial responses and implementing appropriate strategies and interventions for these may be critical for rehabilitation of these patients.

Older adults' experiences regarding discharge from hospital following orthopaedic intervention: a metasynthesis

PURPOSE

To identify and synthesise qualitative literature on the older adults' perspectives of being discharged from hospital following orthopaedic intervention.

METHODS

A systematic search of nine databases, for qualitative research published between 1950 and December 2010, exploring the lived experience of older adults being discharged from hospital following orthopaedic surgery was undertaken. Included papers were evaluated using the Critical Appraisal Skills Programme (CASP) quality guidelines. Data were extracted and themes synthesised, using an EXCEL spreadsheet to assist with organisation of data.

RESULTS

From the 16 papers included in the review, four themes were identified: 1) mental outlook; 2) loss of independence; 3) function and activity limitations; and 4) coping with pain. Mental outlook was central to the other three themes.

CONCLUSIONS

Older adults' experiences around hospital discharge, collected through qualitative research, provide health authorities with valuable information that could be used in care pathway planning. Health professionals involved in in-patient and community care should be aware that a perceived loss of independence, function and activity limitations, and the ability to cope with pain can influence mental outlook and consequently rehabilitation.

Utility of the RT3 triaxial accelerometer in free living: an investigation of adherence and data loss

There is strong evidence for the protective effects of physical activity on chronic health problems. Activity monitors can objectively measure free living occupational and leisure time physical activity. Utility is an important consideration when determining the most appropriate monitor for specific populations and environments. Hours of activity data collected, the reasons for activity hours not being recorded, and how these two factors might change over time when using an activity monitor in free living are rarely reported. This study investigated user perceptions, adherence to minimal wear time and loss of data when using the RT3 activity monitor in 21 healthy adults, in a variety of occupations, over three (7 day) repeated weeks of measurement in free living. An activity diary verified each day of monitoring and a utility questionnaire explored participant perceptions on the usability of the RT3. The RT3 was worn for an average of 14 h daily with 90% of participants having complete data sets. In total 6535.8 and 6092.5h of activity data were collected from the activity diary and the RT3 respectively. An estimated 443.3h (6.7%) of activity data were not recorded by the RT3. Data loss was primarily due to battery malfunction (45.2%). Non-adherence to wear time accounted for 169.5h (38.2%) of data loss, of which 14 h were due to occupational factors. The RT3 demonstrates good utility for free living activity measurement, however, technical issues and strategies to manage participant adherence require consideration with longitudinal and repeated measures studies.

Transmural gradient of leukocyte-endothelial interaction in the rat gastrointestinal tract

Gastrointestinal injury usually starts in the superficial mucosa. We investigated whether leukocyte-endothelial interactions were greater in the gastrointestinal mucosa than the submucosa and muscularis in control tissue and after upregulation of adhesion molecules with endotoxin and after chemical insult with nonsteroidal anti-inflammatory drugs. Inactin-anesthetized rats were given either endotoxin, flurbiprofen, or nitric oxide (NO)-flurbiprofen, after which ICAM-1 and P-selectin expression was measured with the dual-label antibody technique. Leukocyte-endothelial interactions in the different gastric layers were assessed after endotoxin using intravital microscopy. Endotoxin caused a two- to threefold increase in ICAM-1 expression in the stomach and duodenum. There was, however, a gradient in expression across the gut wall with the level of expression in the superficial mucosa (per g) being only 10-25% of that in the deeper layers in both control and endotoxin-treated animals. Constituitive expression of P-selectin in control animals was barely detectable. Endotoxin caused a modest increase in mucosal P-selectin but a very significant increase in the deeper layers. Flurbiprofen caused a slight upregulation of ICAM-1 in the gastric mucosa and duodenum, whereas NO-flurbiprofen had no affect on expression. Intravital microscopy revealed no adhesion and virtually no leukocyte rolling in the vessels of the gastric mucosa despite endotoxin treatment. There was, however, some adhesion and significant leukocyte rolling in the submucosa and muscularis. Thus the superficial gastric and duodenal mucosal microcirculations have a much lower density of ICAM-1 and P-selectin and less leukocyte-endothelial interactions than occurs in the deeper layers of the gut wall even during stimulated upregulation with endotoxin.

NMDA receptor involvement in the effects of low dose domoic acid in neonatal rats

We have previously reported that neonatal rats display enhanced sensitivity to domoic acid relative to adults, and that perinatal injections of low doses of domoic acid alter early associational learning in the newborn rat. The current study was designed to further investigate the effects of low dose domoic acid on neonatal odour conditioning and to determine if the observed effects are due in part to an action on NMDA receptors. Groups of rat pups were conditioned to a novel odour on postnatal day (PND) 8, injected with 20 microg/kg domoic acid either alone, or in combination with the NMDA antagonist CPP (or appropriate controls), daily from day 8-14, re-exposed to the conditioning odour or a novel odour on day 9, and tested for odour preference on day 13 using a standard 3-choice paradigm. Results indicated that rats treated with domoic acid spent significantly more time over the conditioning odour than did saline-treated rats when tested on PND 13. This effect was antagonized by concomitant injection of CPP, indicating an involvement of NMDA receptors in the actions of DOM in this paradigm. Rats injected with either saline or CPP alone showed the opposite effect, i.e. a preference for the alternate odour. The results indicate that a very low dose of DOM produces a conditioned odour preference in neonatal rats and that this effect is due in part to NMDA receptor involvement, thereby emphasizing a role for both kainate and NMDA glutamate receptors in implicit memory.

Low doses of domoic acid during postnatal development produce permanent changes in rat behaviour and hippocampal morphology

It is well established that the developing brain is a highly dynamic environment that is susceptible to toxicity produced by a number of pharmacological, chemical and environmental insults. We report herein on permanent behavioural and morphological changes produced by exposing newborn rats to very low (subconvulsive) doses of kainate receptor agonists during a critical window of brain development. Daily treatment of SD rat pups with either 5 or 20 microg/kg of domoic acid (DOM) from postnatal day 8-14 resulted in a permanent and reproducible seizure-like syndrome when animals were exposed to different tests of spatial cognition as adults. Similar results were obtained when animals were treated with equi-efficacious doses of kainic acid (KA; 25 or 100 microg/kg). Treated rats had significant increases in hippocampal mossy fiber staining and reductions in hippocampal cell counts consistent with effects seen in adult rats following acute injections of high doses of kainic acid. In situ hybridization also revealed an elevation in hippocampal brain derived neurotrophic factor (BDNF) mRNA in region CA1 without a corresponding increase in neuropeptide Y (NPY) mRNA. These results provide evidence of long-lasting behavioural and histochemical consequences arising from relatively subtle changes in glutamatergic activity during development, that may be relevant to understanding the aetiology of seizure disorders and other forms of neurological disease.

NO-flurbiprofen maintains duodenal blood flow, enhances mucus secretion contributing to lower mucosal injury

This study investigates possible mechanisms behind the reduced gastrointestinal ulcerogenicity of nitric oxide (NO)-flurbiprofen compared with flurbiprofen. The duodenal mucosa of Inactin-anaesthetised rats was exteriorized for intravital microscopy. Blood flow was measured with laser-Doppler flowmetry (LDF), mucus thickness with micropipettes, ICAM-1 and P-selectin expression with dual-labeled antibody technique, and mucosal integrity by (51)Cr-EDTA permeability. Exposure of the duodenum to flurbiprofen (1.0 mg/ml) for 90 min significantly reduced LDF to 70 +/- 4%, whereas NO-flurbiprofen (1.3 mg/ml) had no significant effect. Mucus accumulation after 60-min exposure was 75 +/- 23 microm (control), -1 +/- 17 microm (flurbiprofen), and 104 +/- 35 microm (NO-flurbiprofen). Mucosal permeability to (51)Cr-EDTA was unchanged in the control and NO-flurbiprofen groups but increased significantly from 1.0 +/- 0.2 to 3.7 +/- 0.7 microl x min(-1) x g(-1) after 90-min exposure to flurbiprofen. Expression of ICAM-1 was significantly increased after oral flurbiprofen but not by NO-flurbiprofen. Positive effects of NO-flurbiprofen compared with flurbiprofen on mucus formation, blood flow, and adhesion molecule expression likely contribute to the reduced mucosal injury observed with NO-flurbiprofen.

How can the uptake of cervical cytology screening be improved?

BACKGROUND

Cervical cancer remains a killer, despite a screening programme designed to detect cases in the early stages of development. A number of factors appear to influence a woman's decision to attend for a smear test. This literature review considers these factors, and whether nurses can play a part in reducing the death rate by dispelling the misapprehensions and misinformation that deter vulnerable women from attending.

CONCLUSION

There is a great need for modification and improvement of the present screening programme if all women who are at risk from cervical cancer are to be encouraged to attend for screening. The attitude of those who conduct smear tests is often crucial in gaining women's confidence--an unpleasant experience might deter a patient from attending again. Other barriers to attendance include administrative errors and lack of knowledge. Given the impact of mass advertising and health promotion campaigns in other areas, such as smoking cessation, there is clearly a need for a similar strategy to be applied to cervical screening.

Bufokinin: immunoreactivity, receptor localization and actions in toad intestine and mesenteric circulation

In this study, we have mapped the immunoreactivity and the binding sites for bufokinin, a tachykinin peptide from the toad intestine. Dense bufokinin-immunoreactive fibers were present at the myenteric plexus, but no cell bodies were stained, suggesting an extrinsic origin. Bufokinin nerve fibers were also associated with submucosal blood vessels and mesenteric arteries. Autoradiographic binding sites for [(125)I]Bolton-Hunter-bufokinin were densely localized over the intestinal circular and longitudinal muscle, submucosal blood vessels and the endothelium of mesenteric arteries. Mesenteric veins had minimal immunoreactivity and binding sites. In the anesthetized toad, topical application of bufokinin onto the mesentery caused a 2.7-fold increase in arterial blood flow, observed using intravital microscopy. This study supports a role for bufokinin as an endogenous spasmogen and hemodynamic regulator in the toad intestine.

Interrelations between plasma homocysteine and intracellular S-adenosylhomocysteine

S-Adenosylhomocysteine, a potent intracellular methylation inhibitor, is suggested as a potential mediator for hyperhomocysteinemia-related vascular changes. We investigated the effect of acute and chronic hyperhomocysteinemia on intracellular S-adenosylhomocysteine and S-adenosylmethionine in rats and humans. Elevated plasma homocysteine in rats infused with homocysteine produced an increase in S-adenosylhomocysteine (P < 0.001) but not S-adenosylmethionine levels (P > 0.05) in various rat tissues. However intraerythrocyte S-adenosylhomocysteine and S-adenosylmethionine levels were not changed in homocysteine-infused rats and human subjects with experimentally acute hyperhomocysteinemia by methionine loading test. In contrast, erythrocyte S-adenosylhomocysteine levels were significantly higher in chronic renal failure patients, who had chronically elevated plasma homocysteine levels, than in either vascular disease patients or healthy controls (P < 0.05). In conclusion, acute hyperhomocysteinemia can increase intracellular S-adenosylhomocysteine levels in tissues actively involved in homocysteine metabolism. The findings are relevant to homocysteine-related endothelial dysfunction since S-adenosylhomocysteine modulates endothelial cell apoptosis.

A combination of midazolam and ketamine for procedural sedation and analgesia in adult emergency department patients

OBJECTIVE

To describe the clinical characteristics of a combination of midazolam and ketamine for procedural sedation and analgesia in adult emergency department (ED) patients.

METHODS

This was a prospective, observational trial, conducted in the ED of an urban level II trauma center. Patients > or = 18 years of age requiring procedural sedation and analgesia were eligible, and enrolled patients received 0.07 mg/kg of intravenous midazolam followed by 2 mg/kg of intravenous ketamine. Vital signs were recorded at regular intervals. The adequacy of sedation, adverse effects, patient satisfaction, and time to reach discharge alertness were determined. Descriptive statistics were calculated using statistical analysis software.

RESULTS

Seventy-seven patients were enrolled. Three were excluded due to protocol violations, three due to lack of documentation, and one due to subcutaneous infiltration of ketamine, leaving 70 patients for analysis. The average age was 31 years, and 41 (59%) were female. Indications for procedural sedation and analgesia included abscess incision and drainage (66%), fracture/joint reduction (26%), and other (8%). The mean dose of midazolam was 5.6 +/- 1.4 mg and the mean dose of ketamine was 159 +/- 42 mg. The mean time to achieve discharge criteria was 64 +/- 24 minutes. Five patients experienced mild emergence reactions, but there were no episodes of hallucinations, delirium, or other serious emergence reactions. Eighteen (25%) patients recalled dreaming while sedated; twelve (17%) were described as pleasant, two (3%) unpleasant, three (4%) both pleasant and unpleasant, and one (1%) neither pleasant nor unpleasant. There were four (6%) cases of respiratory compromise, two (3%) episodes of emesis, and one (1%) case of myoclonia. All of these were transient and did not result in a change in the patient's disposition. Only one (1%) patient indicated that she was not satisfied with the sedation regimen.

CONCLUSIONS

The combination of midazolam and ketamine provides effective procedural sedation and analgesia in adult ED patients, and appears to be safe.

Reflections on intuition and expertise

Reflective practice now appears firmly established in the English speaking world of professional nursing practice and development. Outside this linguistic context, however, the concept seems less well-known. This paper describes an experience drawn from clinical practice and education in French-speaking Switzerland followed by explicit reflection grounded in questions generated by Johns' model for structured reflection. Thus, a concept well-described in the English-language literature underpins an innovative approach to a French-language clinical teaching situation. The professional implications of this situation are explored through meaningful reflection providing new insight into familiar circumstances as they relate to the nurse tutor's role. This exploration is followed by a critical approach to the experience and the subsequent structured reflection in order to address relationships between intuition and expertise and self-awareness through reflection. A hermeneutic perspective provides additional insight into the nurse-patient relationship where both come to the situation with their own 'pre-understandings'. Individual horizons thus endorse a new understanding going beyond taken-for-granted meanings.

Homocysteine enhances neutrophil-endothelial interactions in both cultured human cells and rats In vivo

Despite intense investigation, mechanisms linking the development of occlusive vascular disease with elevated levels of homocysteine (HCY) are still unclear. The vascular endothelium plays a key role in regulating thrombogenesis and thrombolysis. We hypothesized that vascular lesions in individuals with elevated plasma HCY may be related to a dysfunction of the endothelium triggered by HCY. We investigated the effect of HCY on human neutrophil adhesion to and migration through endothelial monolayers. We also examined the effect of HCY on leukocyte adhesion and migration in mesenteric venules of anesthetized rats. We found that pathophysiological concentrations of HCY in vitro induce increased adhesion between neutrophils and endothelial cells. This contact results in neutrophil migration across the endothelial layer, with concurrent damage and detachment of endothelial cells. In vivo, HCY infused in anesthetized rats caused parallel effects, increasing leukocyte adhesion to and extravasation from mesenteric venules. Our results suggest that extracellular H2O2, generated by adherent neutrophils and/or endothelial cells, is involved in the in vitro endothelial cell damage. The possibility exists that leukocyte-mediated changes in endothelial integrity and function may lead to the vascular disease seen in individuals with elevated plasma HCY.

Australian animal ethics committees: we have come a long way

Twenty years ago, Australian biomedical researchers took the first steps along a pathway toward common ground with opponents of the use of animals in science. Leaders of Australian medical research at that time saw the necessity of established science facing the ethical and political challenges that a revived antivivisectionist movement was mounting in the late 1970s and the 1980s.

Intercellular adhesion molecule-1 expression in adjuvant arthritis in rats: inhibition by kappa-opioid agonist but not by NSAID

OBJECTIVE

To quantify intercellular adhesion molecule-1 (ICAM-1) expression in normal and adjuvant arthritic rats and to determine the extent to which ICAM-1 expression in arthritic animals is altered by treatment with a prototype nonsteroidal antiinflammatory drug (NSAID) and a kappa-opioid agonist.

METHODS

Unilateral hind paw inflammation was induced by intradermal injection of Freund's complete adjuvant (FCA) into the right hind paw of female Lewis rats. Polyarthritis was induced by intradermal injection of FCA into the base of the tail of female dark Agouti rats. The NSAID naproxen [5 mg/kg intraperitoneally (ip)] or the kappa-opioid PD117302 (15 mg/kg ip) was administered twice daily throughout the experiment (21 days). ICAM-1 expression was quantified using monoclonal antibodies against rat ICAM-1 that bind to the endothelium in proportion to the degree of adhesion molecule expression.

RESULTS

ICAM-1 expression was significantly upregulated in the joints of affected limbs of animals with both unilateral hind paw inflammation and polyarthritis. In animals treated with PD 117302 and naproxen there was a significant attenuation of arthritis; however, only treatment with PD117302 was able to significantly inhibit the upregulation of ICAM-1 expression in arthritic joints.

CONCLUSION

ICAM-1 expression is upregulated in experimental arthritis. It appears that the kappa-opioid PD117302, but not the NSAID naproxen, inhibits the upregulation of ICAM-1 in arthritic joints, suggesting these agents act via different mechanisms. The ability of the kappa-agonist, PD117302, to inhibit both the inflammation and upregulation of ICAM-1 in arthritic joints emphasizes the potential of kappa-agonists as antiarthritic agents.

Role of neutrophils and mast cells in acute indomethacin-induced small bowel injury in the rat

The aim of this study was to determine whether the injury to the rat jejunum during the first 4.5 h exposure to indomethacin is due to an influx of neutrophils or degranulation of resident mast cells. Indomethacin and vehicle both caused changes in villous morphology (length, width, etc.) while only indomethacin injured the small bowel, as indicated by increased histological lesion score and 51Cr-ethylene diamine tetraacetate (EDTA) flux across the intestinal epithelium. Immunohistochemical staining showed the same small increase in neutrophil density (predominantly in the submucosa) following exposure to vehicle as following exposure to indomethacin. Chronic oral administration of indomethacin for 48 h did cause increased tissue neutrophil density compared to that in vehicle-fed controls. Mast cell depletion (using dexamethasone) did not alter either the indomethacin-induced increase in 51Cr-EDTA clearance or the increase in neutrophil density caused by the vehicle and by indomethacin. However, the lesion score following exposure to indomethacin was significantly lower in mast-cell-depleted animals than in control animals. We conclude that the acute phase of indomethacin-induced intestinal injury is not associated with neutrophil influx. Increased neutrophils seen after chronic indomethacin may result from injury rather than be causative. Mast cells appear to exacerbate the initial stages of indomethacin-induced intestinal injury.

Portal hypertension enhances endotoxin-induced intercellular adhesion molecule 1 up-regulation in the rat

BACKGROUND & AIMS

Liver disease or portosystemic shunting enhances th e sensitivity to endotoxin. The aim of this study was to investigate whether intercellular adhesion molecule 1 (ICAM-1) expression in response to endotoxin may be dysregulated in an animal model of portal hypertension.

METHODS

Portal hypertension was induced by partial portal vein ligation. Sham-operated animals served as controls. ICAM-1 expression was measured using radiolabeled antibodies under baseline conditions or 5 hours after treatment with either endotoxin or recombinant tumor necrosis factor (TNF). Immunoreactive plasma TNF was also measured.

RESULTS

Under baseline conditions, ICAM-1 expression in all organs studied was similar in portal-hypertensive and sham-operated rats. ICAM-1 up-regulation after a high dose of endotoxin (5 mg/kg) was similar in both groups of animals. However, portal-hypertensive animals showed a significantly higher ICAM-1 expression in response to low doses of endotoxin (0.1-10 microgram/kg). The response to a low (but not a high) dose of recombinant TNF was also significantly enhanced in portal-hypertensive animals. In addition, portal-hypertensive rats had higher plasma TNF levels after treatment with endotoxin or recombinant TNF.

CONCLUSIONS

Portal hypertension induces an exaggerated ICAM-1 up-regulation in response to endotoxin, which is related to an increased production and decreased clearance of the cytokine.

Regional differences in constitutive and induced ICAM-1 expression in vivo

The aim of the present study was to characterize and compare the expression of intercellular adhesion molecule 1 (ICAM-1) on unstimulated and endotoxin-challenged endothelial cells in different tissues of the rat. ICAM-1 expression was measured using 125I-labeled anti-rat ICAM-1 monoclonal antibody (MAb) and an isotype-matched control MAb labeled with 131I (to correct for nonspecific accumulation of the binding MAb). Under baseline conditions, ICAM-1 MAb binding was observed in all organs. The binding of 125I-ICAM-1 MAb varied widely among organs, with the largest accumulation (per g tissue) in the lung, followed by heart (1/30th of lung activity), splanchnic organs (1/50th of lung activity), thymus (1/100th of lung activity), testes (1/300th of lung activity), and skeletal muscle (1/800th of lung activity). Endotoxin induced an increase in ICAM-1 MAb binding in all organs except the spleen. Endotoxin-induced upregulation of ICAM-1 was greatest in heart and skeletal muscle (5- to 10-fold), whereas the remaining organs exhibited a two- to fourfold increase in ICAM-1 expression. Maximal upregulation of ICAM-1 occurred at 9-12 h after endotoxin administration. A dose-dependent increase in ICAM-1 expression was elicited by 0.1-10 microgram/kg, with higher doses (up to 5 mg/kg) producing no further increment. Induction of ICAM-1 mRNA after endotoxin was observed in all tissues examined (lung, heart, intestine), peaked at 3 h, and then rapidly returned to control levels. These findings indicate that ICAM-1 is constitutively expressed on vascular endothelium in all organs of the rat and that there are significant regional differences in the magnitude and time course of endotoxin-induced ICAM-1 expression.

Role of leukocytes in indomethacin-induced small bowel injury in the rat

This study assesses the role of neutrophils in indomethacin-induced small bowel injury and determines the influence of intestinal pH on the magnitude of this injury. Rat jejunum was perfused via the lumen with buffer, and mucosal injury was assessed by blood-to-lumen clearance of 51Cr-EDTA and quantitative histology. Reduction in luminal pH from 7.4 to 6.0 in the presence of indomethacin (1.0 mg/ml) increased 51Cr-EDTA clearance from 2.0 +/- 0.1 to 6.5 +/- 0.3 microliter.min-1.g-1. Indomethacin caused a reduction in villus length, an increase in villus width, and an increase in lesion score. Depletion of neutrophils with antiserum largely prevented the increase in 51Cr-EDTA clearance and morphological changes. Intravenous indomethacin given at a dose to mimic therapeutic plasma levels (1 mg/kg iv) had no significant effect on 51Cr-EDTA clearance but caused similar morphological changes to those observed following intraluminal administration. The data suggest that neutrophils play a role in acute indomethacin injury and that the drug given intravenously can cause morphological changes without necessarily altering mucosal permeability to 51Cr-EDTA.

Mechanisms of acute and chronic intestinal inflammation induced by indomethacin

The objective of this study was to characterize the mechanisms of acute and chronic intestinal mucosal injury and inflammation induced by subcutaneously injected indomethacin (Indo). One injection of Indo (7.5 mg/kg) produced acute injury and inflammation in the distal jejunum and proximal ileum that were maximal at three days and completely resolved within one week. Two daily subcutaneous injections of Indo produced a more extensive and chronic inflammation that lasted in an active form in more than 75% of the rats for at least two weeks. Epithelial injury, as measured by enhanced mucosal permeability, was significantly elevated only at one day in the acute model (one injection) but was persistently elevated in the chronic model (two injections). Bile duct ligation completely attenuated increased mucosal permeability in the acute model, however, depletion of circulating neutrophils had no effect. Neither Indo (0-0.1 mg/ml) nor normal bile was cytotoxic to cultured rat intestinal epithelial cells; however, they synergistically promoted significant cytotoxicity. Bile collected from rats treated with Indo was cytotoxic towards the epithelial cells in a dose-dependent manner. Sulfasalazine and metronidazole (100 mg/kg/day, both) attenuated enhanced mucosal permeability in the chronic model. Massive bacterial translocation into the mesenteric lymph nodes, liver, and spleen following two injections of Indo was significantly attenuated by metronidazole. We conclude that: (1) a single injection of Indo produces acute intestinal mucosal injury and inflammation that resolve completely within three to seven days, whereas two daily injections of Indo produce both acute and chronic injury and inflammation, (2) enterohepatic circulation of Indo is important in promoting the acute phases of injury and inflammation, (3) circulating neutrophils do not play a role in the pathogenesis of this model, and (4) endogenous bacteria play an important role in exacerbating and/or perpetuating the chronic phases of injury and inflammation.

Spatial and Temporal Variation in Competitive Effects on Soil Moisture and Pine Response

The effects of different plant life-forms, including a bunch grass species, Andropogon virginicus L. (broomsedge), and a sprouting deciduous tree species, Liquidambar styraciflua L. (sweetgum), on soil moisture and competitive responses of a transplanted coniferous tree seedling, Pinus taeda L. (loblolly pine), were investigated. Addition of the bunch grass and/or hardwood sprouts either had no effect or increased soil moisture in the surface soil (0-14 cm) depending on the time, while addition of sweetgum and/or broomsedge (greatest density alone) decreased soil moisture in deeper portions of the solum during the summer months. Soil moisture available to pine seedlings at various points in time was assessed by measuring predawn xylem pressure potential. Temporal variation in predawn xylem pressure potential was accounted for through a water stress integral approach. More than half of the variation in pine size after one growing season could be accounted for by the water stress integral.

Leukocyte--endothelial cell adhesion induced by ischemia and reperfusion

Reperfusion of ischemic tissues is associated with an enhanced production of inflammatory mediators, increased rolling, adherence, and emigration of leukocytes in postcapillary venules, and vascular protein leakage. There is a growing body of evidence that the leukocyte--endothelial cell interactions are largely responsible for the microvascular dysfunction induced by ischemia--reperfusion. Oxygen radicals, produced by xanthine oxidase and other enzymes, appear to play an important role in initiating and amplifying the inflammatory response elicited by ischemia--reperfusion, while neutrophilic proteases contribute significantly to the injury response. The magnitude of the inflammatory responses observed during ischemia and reperfusion is also influenced by adhesion forces generated by specific glycoproteins expressed on the surface of granulocytes and microvascular endothelium, as well as shear forces that are generated by the movement of blood within the microcirculation. Manipulation of free-radical production, leukocyte--endothelial cell adhesion, and (or) intravascular shear forces provides an effective means for attenuating the deleterious influences of ischemia--reperfusion on the microvasculature.

Leukocyte adhesion in local versus hemorrhage-induced ischemia

The objective of this study was to compare the leukocyte-endothelial cell adhesive interactions elicited in postcapillary venules by either local ischemia-reperfusion or hemorrhage-reperfusion. Leukocyte rolling, adherence, and emigration were monitored in cat mesenteric venules exposed to an 85% reduction in blood flow (induced by either hemorrhage or local restriction of arterial inflow) for 1 h, followed by 1 h reperfusion. Leukocyte-endothelial cell interactions, venular diameter, and red blood cell velocity were measured during baseline, ischemia, and reperfusion periods. Both local and hemorrhage-induced ischemia reperfusion caused a reduction in leukocyte rolling velocity and increases in leukocyte adherence and emigration. Quantitatively, the adherence and emigration responses in both ischemia models were nearly identical. However, the two models differed in their response to immunoneutralization of the leukocyte adhesion glycoprotein CD11/CD18 with monoclonal antibody (MAb) IB4. The MAb had a more profound effect in attenuating leukocyte adherence and emigration in the local ischemia model. These results indicate that different factors may contribute to leukocyte-endothelial cell adhesive interactions observed in local vs. systemic models of ischemia-reperfusion.

Effect of aspirin on ulcer site blood flow in cat stomachs

Radioactive microspheres were used to measure blood flow in the cat stomach during exposure to saline, 0.075 M HCl, and then 15 and 30 min after exposure to 20 or 40 mM aspirin in HCl. At the end of the experiment, the stomach wall was divided into ulcerated regions and adjacent nonulcerated areas. When exposed to saline, both regions had similar blood flow: 27 +/- 5 and 25 +/- 5 ml.min-1.100 g-1 (means +/- SE). Addition of acid caused a significant increase in blood flow to 41 +/- 7 ml.min-1.100 g-1 only at those sites that eventually ulcerated in the presence of aspirin. In the adjacent nonulcerated regions, blood flow was 31 +/- 5 ml.min-1.100 g-1 and was not significantly greater than the flow recorded during saline exposure. Aspirin caused ulcer site blood flow to increase dramatically to 89 +/- 12 and 122 +/- 18 ml.min-1.100 g-1 after 15 and 30 min, whereas the adjacent nonulcerated tissue rose to 40 +/- 6 and 44 +/- 5 ml.min-1.100 g-1, respectively. The ulcer site hyperemia with acid alone suggests higher mucosal permeability in these regions allowing back-diffusion of acid and injurious agents. The present data obtained in the cat do not support the notion that ischemia plays a role in initiating nonsteroidal anti-inflammatory drug (NSAID)-induced ulcers, but rather that acute NSAID ulcers are associated initially with a hyperemia.

Morphologic assessment of leukocyte-endothelial cell interactions in mesenteric venules subjected to ischemia and reperfusion

Intravital microscopic studies of the mesenteric microcirculation have demonstrated that leukocyte adherence and emigration in postcapillary venules are a characteristic feature of tissues exposed to ischemia-reperfusion. The objectives of this study were to determine whether: (1) neutrophils are the predominant leukocytes that adhere and emigrate in postischemic mesenteric venules, and (2) leukocyte adherence and/or emigration are a prerequisite for reperfusion-induced increases in venular permeability. Leukocyte kinetics in cat mesenteric venules (25-35 microns diameter) were evaluated using both intravital microscopy and quantitative morphometry. The intestine and mesentery were exposed to 60 min of ischemia, followed by 60 min reperfusion. Some animals were pretreated with a monoclonal antibody (MoAb IB4) against the leukocyte adhesion glycoprotein, CD11/CD18. Vessels observed by intravital microscopy and adjacent venules of similar diameter were excised and processed for light (LM) and electron microscopy (EM). Horseradish peroxidase (HRP), administered intravenously, was used to assess vascular permeability by EM. By LM, the control (nonischemic) mesentery is sparsely populated by plasma cells, mast cells, and leukocytes; 30-50% of the resident population is neutrophils. Ischemia-reperfusion led to a significant increase in the number of extravascular cells, with neutrophils accounting for greater than 80% of the total cell population. Control and ischemic venules demonstrated no leakage of HRP into the interstitium. However, venules exposed to ischemia and reperfusion demonstrated HRP leakage between endothelial cells and into the surrounding interstitium; neutrophils were adherent to the luminal surface of the endothelium, transmigrating the vessel wall, and in the surrounding interstitium. Animals pretreated with MoAb IB4 presented the same cell profile as nonischemic controls, with no adherent or transmigrating neutrophils. However, some HRP leakage was noted following reperfusion in venules treated with MoAb IB4. The results of this study indicate that: (1) neutrophils are the predominate leukocytes that adhere and emigrate in postischemic venules, and (2) inhibition of leukocyte adhesion does not completely prevent the venular dysfunction associated with ischemia-reperfusion.

Role of CD11/CD18 in shear rate-dependent leukocyte-endothelial cell interactions in cat mesenteric venules

In vivo microscopy was used to assess the relationships among shear rate (and shear stress), leukocyte rolling velocity, and leukocyte adherence in a cat mesentery preparation. Shear rate in individual venules and arterioles of 25-35 microns diameter were varied over a wide range by graded occlusion of an arterial loop. There was a linear decline in leukocyte rolling velocity (Vwbc) as red cell velocity (Vrbc) was reduced. The ratio Vwbc/Vrbc remained constant despite variations in shear stress from 5-25 dyn/cm2. A reduction in shear stress was associated with an increased leukocyte adherence, particularly when Vwbc was reduced below 50 microns/s. Reduction in wall shear rate below 500 s-1 in arterioles allowed 1-3 leukocytes to adhere per 100 microns length of vessel, while venules exposed to the same shear rates had 5-16 adherent leukocytes. In arterioles, leukocyte rolling was only observed at low shear rates. At shear rates less than 250 s-1 leukocyte rolling velocity was faster in arterioles than venules, and the ratio Vwbc/Vrbc for arterioles was 0.08 +/- 0.02, which was fourfold higher than the ratio obtained in venules at similar shear rates. Pretreatment with the CD18-specific antibody (mAb) IB4 increased leukocyte rolling velocity in venules by approximately 20 microns/s at red cell velocities below 2,000 microns/s. mAb IB4 largely prevented the leukocyte adherence to arterioles and venules, and increased the ratio Vwbc/Vrbc observed in venules at low shear elicit a CD18-dependent adhesive interaction between leukocytes and microvascular endothelium, and that differences in shear rates cannot explain the greater propensity for leukocyte rolling and adhesion in venules than arterioles.

Ethanol enhances leukocyte-endothelial cell interactions in mesenteric venules

In vivo studies have implicated neutrophils in the gastric mucosal injury produced by intraluminal administration of ethanol. However, in vitro studies indicate that ethanol inhibits various neutrophil functions such as adherence, chemotaxis, and degranulation. The aim of the present study was to assess whether ethanol, at clinically relevant concentrations, is proinflammatory in vivo. Ethanol (0.2, 1.0, 2.0, and 4.0%) was applied to the surface of the cat mesentery, and neutrophil adherence to venules (30 microns diam) and extravasation into the interstitium were quantitated using intravital microscopy. Hemodynamic parameters were also measured (venular diameter, red blood cell velocity, and leukocyte rolling velocity) or calculated (venular blood flow and wall shear stress). In this model ethanol produced a dose-dependent increase in neutrophil adherence and extravasation. The increase in leukocyte-endothelial cell interactions could not be attributed to alterations in hemodynamic factors. Pretreatment of animals with a monoclonal antibody (MoAb IB4) directed to the neutrophil CD11/CD18 adherence complex completely prevented the ethanol-induced neutrophil adherence and extravasation. Pretreatment with a leukotriene B4 (LTB4)-receptor antagonist (SC 41930) or a platelet-activating factor (PAF)-receptor antagonist (WEB 2170) did not alter the ethanol-induced neutrophil-endothelial interactions. We conclude that ethanol is proinflammatory at concentrations which may be achieved in the mucosal interstitium during acute alcohol intoxication. The ethanol-induced leukocyte adherence and extravasation is dependent on the expression of adhesive glycoproteins. The inflammatory mediators, PAF and LTB4, do not appear to play an important role in the leukocyte-endothelial cell interactions initiated by ethanol.

Role of blood flow in gastric acid secretion

The relationship between gastric acid secretion and blood flow has been investigated with a variety of different blood flow techniques including aminopyrine clearance, hydrogen gas clearance, intravital microscopy, laser-Doppler flowmetry, radioactive microspheres, and the elimination of inert gases. The most commonly used technique, aminopyrine clearance, predicts that increasing acid secretion is accompanied by a parallel increase in blood flow. However, the efficiency of clearance of aminopyrine is low in the nonsecreting stomach and increases as secretion rate increases. This precludes the use of aminopyrine clearance as a reliable measure of gastric mucosal blood flow at all but the highest steady-state level of acid secretion and casts doubt on the findings with this technique. Other methods for measuring blood flow indicate that there is no simple relationship between secretion and flow, with some studies finding that secretion and flow change in parallel and others finding that secretion varies quite independently of flow to the mucosa. One consistent finding is a strong correlation between stimulated acid secretion and gastric oxygen consumption. Both acid secretion and oxygen consumption fall if celiac blood flow is reduced below a critical value, which in the anesthetized dog stomach is approximately 30-40 ml.min-1.100 g-1. Driving blood flow above this value does not increase oxygen consumption and acid secretion, i.e., they reach a plateau. The shape of this relationship with its flow-dependent and flow-independent portions is used to explain the apparently contradictory findings in the literature regarding gastric acid secretion and blood flow.

Gradual reintroduction of oxygen reduces reperfusion injury in cat stomach

Recent studies have shown that oxygen-derived free radicals are responsible for a major portion of ischemia-reperfusion injury in the stomach. The oxygen radicals are produced during reperfusion when oxygen delivery to the tissue increases. In the present study we investigate the effect on mucosal injury of regulating the rate of reintroduction of oxygen to the stomach after ischemia. Local gastric ischemia was achieved by reducing celiac artery pressure to 30 mm Hg for 1 h. Ischemic injury was assessed by measuring the loss of 51Cr-labeled red blood cells across the gastric mucosa. Mucosal blood loss was negligible before and during the ischemia period but increased to 0.178 ml.min.-1.100 g-1 during reperfusion. When blood flow to the stomach was gradually returned to normal after ischemia by increasing celiac artery pressure by 10 mmHg every 10 min, the mucosal blood loss was reduced to 0.013 ml.min.-1.100 g-1. If the stomach was vascularly perfused with low PO2 (34 mmHg) blood for 1 h after ischemia before being returned to normal arterial perfusion, the mucosal blood loss was also reduced to 0.063 ml.min.-1.100 g-1. When the stomach was made hypoxemic for 1 h rather than ischemic by perfusing the vasculature with low PO2 (29 mmHg) blood then reperfused with normoxic blood, there was very little mucosal bleeding (0.014 ml.min.-1.100 g-1). The data indicate that gastric mucosal bleeding after ischemia is reduced if the tissue is returned slowly to a normal PO2. These findings support the concept that reperfusion injury is due largely to the production of oxygen radicals.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of neutrophils in hemorrhagic shock-induced gastric mucosal injury in the rat

Gastric mucosal clearance of 51Cr-labeled red blood cells (51Cr-RBC) was measured in rats during a 30-min control period, a 30-min ischemic period (hemorrhage to 27 mmHg arterial pressure), and a 60-min reperfusion period (reinfusion of shed blood). In untreated (control) rats, a dramatic rise in the leakage of 51Cr-labeled red blood cells into the gastric lumen was observed during the reperfusion period. Treatment with neutrophil antiserum attenuated 51Cr-labeled red blood cell flux into the gastric lumen. Using the radioactive microsphere technique, neutrophil-depleted animals were shown to have higher blood flows in the ischemic period than the untreated rats. Bleeding of untreated rats to a mean arterial pressure of 40 mmHg resulted in blood flows that were not different from those in antiserum-treated rats bled to 27 mmHg and leakage of 51Cr-labeled red blood cells similar to that measured in antiserum-treated rats. The results of this study indicate that neutrophils play an important role in hemorrhagic shock-induced gastric bleeding.

Gastric injury induced by hemorrhage, local ischemia, and oxygen radical generation

Gastric mucosal injury caused by local intra-arterial generation of oxygen-derived free radicals was compared with gastric injury caused by 30 min of hemorrhage-induced ischemia (systemic pressure of 30 mmHg) or local ischemia (celiac artery pressure of 30 mmHg). The index of injury was the loss of 51Cr-labeled red cells across the gastric mucosa. Generation of oxygen radicals in the celiac artery caused a rapid increase in mucosal blood loss during the period of radical generation (0.029 +/- 0.013 ml X min-1 X 100 g-1, mean +/- SE), and this loss was maintained after radical production ceased (0.041 +/- 0.018 ml X min-1 X 100 g-1). Local ischemia produced similar mucosal injury; however, this occurred after reperfusion of the stomach (0.038 +/- 0.006 ml X min-1 X 100 g-1) and not during the ischemic episode (0.001 +/- 0.0003 ml X min-1 X 100 g-1). Hemorrhage-induced ischemia produced a threefold greater mucosal blood loss (0.133 +/- 0.048 ml X min-1 X 100 g-1) than local ischemia. The results of this study indicate that oxygen radicals generated enzymatically in the blood supply to the stomach cause mucosal bleeding of similar magnitude to that observed after local ischemia and that gastric ischemia induced by systemic hypotension produces more severe gastric injury than the same level of local hypotension.

Proarrhythmic effects of an oxygen-derived free radical generating system on action potentials recorded from guinea pig ventricular myocardium: a possible cause of reperfusion-induced arrhythmias

Standard microelectrode techniques were used to study the effects of a free radical generating system on action potentials recorded from guinea pig ventricular myocardium. Free radicals were generated by mixing xanthine oxidase (0.02-0.04 mu/ml) with the superfusate-modified Locke's solution containing purine 2.3 mM. The system was validated by demonstrating that it could reduce cytochrome C at a rate of 15.9 +/- 1.5 mol/l/min. This rate was decreased to 3.0 +/- 0.3 (p less than 0.001) in the presence of superoxide dismutase (12 mg/100 ml), and the reaction was absent if xanthine oxidase and purine were premixed for 60 minutes prior to adding cytochrome C. Superfusion of guinea pig ventricular strips with the free radical generating system (20-30 minutes) resulted in a highly significant reduction in resting potential from -79.3 +/- 1.8 mV to -70.9 +/- 1.4 mV (p less than 0.0001, n = 6) and in action potential amplitude from 110.9 +/- 2.2 mV to 101.7 +/- 4.0 mV (p less than 0.0001). There was an accompanying fall in maximum rate of depolarization (Vmax) from 254.1 +/- 17.7 V/sec to 207.1 +/- 18.6 V/sec (p less than 0.01) and no significant change in action potential duration. These changes were accompanied by spontaneous activity in 3 of 6 preparations and reversed after 20-30 minutes washing in Locke's solution. They were largely abolished by adding superoxide dismutase (12 mg/100 ml) to the superfusate and completely absent if the xanthine oxidase and purine were premixed for 60 minutes before superfusing the myocardium. We conclude that the phenomena observed may contribute to the genesis of reperfusion arrhythmias.

Charge selectivity of rat intestinal capillaries. Influence of polycations

The role of fixed anionic sites on the intestinal capillary wall in transvascular protein exchange was assessed by neutralizing the negative charges with polycations. The studies were performed in anesthetized rats with an intestinal lymph cannula. Intestinal lymph flow and lymph and plasma total protein concentrations were measured at regular intervals before and after intravenous infusion of either protamine sulfate, poly-L-lysine, or poly-ethyleneimine. Protamine sulfate infusion produced an eightfold increase in lymph flow and a fivefold increase in lymph protein clearance. Lymph flow increased 4.6-fold and lymph protein clearance increased 3.6 times over control in rats receiving the poly-L-lysine infusion. Polyethyleneimine infusion produced results comparable in magnitude to protamine sulfate; however, the animals were unable to tolerate this agent. The enhanced transcapillary protein fluxes produced by the polycation infusions suggest that fixed anionic sites normally impede the egress of proteins from the intestinal vasculature.

Descending noradrenergic pathways involved in the A5 depressor response

The objective of the present study was to analyze the anatomical basis of the A5 depressor response and to test if the putative neurotransmitter noradrenaline is involved in the response. Two approaches were used; one was neuroanatomical and the other was pharmacological. First, the retrograde transport method in which two fluorescent markers (Fast blue and rhodamine microspheres) was used in combination with the indirect immunofluorescence technique to establish that A5 catecholamine neurons project to both the spinal cord and the region of the nucleus tractus solitarii (NTS). Second, we analyzed the effects of 6-hydroxydopamine (6-OHDA) lesions of the spinal cord and/or NTS area on the A5 depressor response. This response was elicited by a 80-nl microinjection of L-glutamate (500 mM) into the A5 region in pentobarbital anesthetized rats; it was characterized by a decrease in blood pressure and heart rate. After destruction of various noradrenergic terminal fields we have found that intraspinal injections of 6-OHDA caused a 30% reduction in the blood pressure component of the A5 depressor response and a transient depression of the bradycardic response. This result suggests that only a small portion of the A5 depressor response depends on the descending A5 spinal pathway. Injections of 6-OHDA into the NTS region caused a transient depression of the A5 depressor response, and by 7-14 days postinjection, the response returned to normal. After combined 6-OHDA injections into the spinal cord and NTS area, the blood pressure and heart rate components of the A5 depressor response were reduced to 80% of the control level at 3 days postinjection. By 14 days, even with severe depletion of noradrenaline in the spinal cord (96%) and a moderate depletion of noradrenaline in the NTS (50%), the A5 response was restored to about 80% of its original magnitude, suggesting some type of functional recovery occurs in this system. Third, the blood pressure decrease elicited by L-glutamate stimulation of the A5 cell group was unaffected by pharmacological blockade of the heart. In addition, this response appeared to be normal in rats that had both their autonomic supply to the heart blocked pharmacologically and their spinal cord noradrenaline levels depleted (14 days after intraspinal 6-OHDA injections). These data suggest that the major A5 depressor response operates mainly by inhibition of the sympathetic outflow involved in control of total peripheral resistance and that this system is controlled by a descending spinal pathway which probably does not use noradrenaline as a neurotransmitter.

Measurement of capillary pressure in humans using a venous occlusion method

The venous occlusion technique was used to measure capillary pressure in the forearm and foot of man over a wide range of venous pressures. In six recumbent subjects venous pressure (Pv) in the forearm (mean +/- SE) was 9.3 +/- 1.4 mmHg and the venous occlusion estimate of capillary pressure (Pc) was 17.0 +/- 1.6 mmHg, whereas in another six subjects Pv in the foot was 17.1 +/- 1.2 mmHg and Pc was 23.4 +/- 2.5 mmHg. Venous pressure in the limbs was increased either by changes in posture or by venous congestion with a sphygmomanometer cuff. On standing Pv in the foot increased to 95.2 +/- 1.5 mmHg and Pc rose to 112.8 +/- 3.1 mmHg. The relationship established between venous pressure and capillary pressure in the forearm is Pc = 1.16 Pv + 8.1, whereas in the foot the relationship is Pc = 1.2 Pv + 1.6. The magnitude and duration of the changes in capillary pressure were also recorded during reactive hyperemia. The venous occlusion method of measuring capillary pressure is simple and easily applied to studies in humans.