In-vivo analysis of Protec™ and β-glucan supplementation on innate immune performance and intestinal health of rainbow trout

Functional diets are often given to fish during key stages to improve health through the interaction of the feed components with the host intestine. The additional factors added in these diets are known to modulate the immune response and as such may also offer protection against pathogenic challenges. The present study was undertaken to evaluate whether β-glucan supplementation for 6 weeks can alter the magnitude of immune response to immunological challenges and subsequently offer an improved innate immune response to bacterial challenge in rainbow trout. Two experimental diets were used to study these effects: a basic commercial diet supplemented with β-glucan and a commercially available functional diet (Protec™) that has β-glucan as a functional component in addition to other components were compared to a basic commercial control diet. No significant differences were observed in biometric data. Histological analysis revealed a significantly greater number of goblet cells in the fish fed Protec™ and β-glucan diets compared to those fed a control diet. Cell marker gene expression of distal intestine leucocytes indicated higher expression of T- and B-cells marker genes to both the β-glucan containing diets in comparison to control. The Protec™ diet demonstrated modulation of innate immune markers after 6 weeks of feeding with key antimicrobial genes (SAA, HAMP, IL-1β and TNFα) showing significant increases compared to the other diets. After stimulation with both PAMPs and an immune challenge with A. salmonicida fish fed the β-glucan diet and the Protec™ exhibited modulation of the innate immune response. An immune challenge with A. salmonicida was carried out to identify if dietary composition led to differences in the innate immune response of rainbow trout. Modulation of the magnitude of response in some immune genes (SAA, IL-1β and HAMP) was observed in both the distal intestine and head kidney in the Protec™ and β-glucan fed fish compared to those fed the control diet.

4 HIGH-PROTEIN, HIGH-CALORIE ICE-CREAM PRESCRIPTION IN AN ORTHOGERIATRIC INPATIENT POPULATION

Background

At a major trauma centre in the South of Ireland, all older adults admitted with hip and other fragility fractures are co-managed by the Orthopaedic & Orthogeriatric services with an average of over 500 hip fractures a year. A recent publication by described improving calcium and protein intake by using dairy foods as a readily accessible intervention that reduces the risk of falls and fractures in aged care residents. Foods used included cheese, yoghurt and milk being described as “low cost” and “palatable”. Other dairy alternatives such as ice-cream are not used as not protein or calcium rich. In Ireland high calorie-high protein ice-cream is widely available (10g protein, 220 kcal/100g serving).

Methods

A point prevalence survey relating to the preference of calcium and/or protein rich food ‘snacks’ was completed on 20 inpatients in hospital with a hip or other fragility fracture.

Survey Questions: (1) Would an additional calcium and/or protein rich food snack be acceptable to you?; (2) Which food snack would you prefer: a serving of milk, cheese, yogurt, or ice-cream?; (3) What time would you prefer to eat an additional snack? Morning, afternoon, or evening?

Results

The majority of participants (95%; 19/20) replied an additional snack would be acceptable. With reference to snack preference: 35% (7/20) would prefer a serving of yoghurt, 30% (6/20) ice-cream, 25% (5/20) cheese and only 10% (2/20) would prefer milk. The majority said they would prefer to be offered a snack in the afternoon (55%; 11/20).

Conclusion

Our inpatient population would benefit from the addition of such snacks to optimise recovery and bone health. Patient preference needs to inform any dietary or menu modifications. Following our survey, in addition to calcium and vitamin D supplementation, high-protein high-calorie ice-cream is offered and prescribed to patients if eating less than 50% of their energy dense meals.

Gut Associated Lymphoid Tissue (GALT) primary cells and stable cell lines as predictive models for intestinal health in rainbow trout (Oncorhynchus mykiss)

The use of functional feeds for farmed fish is now regarded as a key factor in improving fish health and performance against infectious disease. However, the mechanisms by which these nutritional components modulate the immune response are not fully understood. The present study was undertaken to identify the suitability of both primary gut-associated lymphoid tissue (GALT) leucocyte cells and established rainbow trout cell lines as potential alternative methods to test functional feed ingredients prior to full fish feeding trials that can take months to complete. In addition to the primary GALT culture cells, the two rainbow cell lines RTS11 and RTgutGC which are from macrophage and gut epithelial cells, respectively. The cells were stimulated with a variety of pathogen associated molecular patterns (PAMPs) (PHA and Poly I:C) and recombinant rainbow trout IL-1β (rIL-1β), a proinflammatory cytokine, additionally two forms of β-glucan, a prebiotic commonly used aquafeeds were used as stimulants. From this, the suitability of cell models as a health screen for functional feeds was assessed. GALT leucocytes were deemed most effective to act as a health screen over the 4hr time point demonstrating responses to Poly I:C, PHA, and rIL-1β. RTS11 and RTgutGC also responded to the stimulants but did not give a strong T-cell response, most likely reflecting the nature of the cell type as opposed to the mixed cell populations from the primary GALT cell cultures. When stimulated with both forms of β-glucan, GALT leucocytes demonstrated a strong proinflammatory and T-cell response.

Immune responses to prebiotics in farmed salmonid fish: How transcriptomic approaches help interpret responses

Within aquaculture, prebiotics are composed of complex carbohydrate molecules that cannot be digested by the fish directly but are metabolised by the microbial communities within the host gut, with the desire that "healthy" bacterial species are promoted with subsequently improved performance of the fish, there are likely some direct responses of intestinal cells to these dietary components. The sources and processing of prebiotics, which fall under the overarching theme of "functional feeds" are highly varied between species and types of prebiotics administered. How these feeds exert their effect, and the host responses are hard to determine, but new technologies and the development of high-throughput technologies (omics) are enabling the mechanisms and methods of action to be further understood. The recent advances in the availability of 'omics' technologies with the transition from single gene assays to microarray and RNA-seq in fish health have enabled novel functional ingredients to be analysed. This review will focus on recent studies on targeted gene expression and 'omics' technologies to characterize immune responses. Comparisons between the immunomodulatory effect of different prebiotics have been made and specific examples of how transcriptomics techniques have been used to identify immune responses to prebiotics are given.

127 ‘BONE HEALTH AND FRACTURE RISK ASSESSMENT IN COPD EXACERBATIONS DURING HOSPITALISATION- ROOM FOR IMPROVEMENT?’

Background

COPD increases the risk of osteoporosis and international guidelines recommend that such patients undergo fracture risk assessment, referral for densitometry and appropriate management. We aimed to identify if patients admitted to our hospital with COPD exacerbation underwent assessment and were prescribed bone protection medication.

Methods

All admissions with COPD exacerbation to an Irish level 2 hospital between July 2020 and July 2021 were identified. The discharge summaries were screened for information regarding the presence of fracture risk and bone health assessment. Discharge prescriptions were examined for calcium, vitamin d and anti-osteoporosis medications. Radiology reports were screened for fragility fractures.

Results

Between July 2020–2021, there were 3,840 presentations to the medical assessment unit. Forty-six patients were admitted with a diagnosis of COPD exacerbation, mean age 72 (56% female). Seventy eight percent were classified as having GOLD Stage D disease with 28% receiving long term oxygen therapy. Mean number of hospitalisations per year per patient was 1.91 ± 1.2. Forty-three percent had laboratory evidence of bone health assessment during admission. Only 50% of patients were discharged on vitamin d replacement; 22% on calcium supplementation and 4% on osteoporotic medications. Regarding previous fractures, 9% had evidence of fragility fracture described on radiology reports, this was not mentioned on any hospital discharge letter.

Conclusion

This study suggests that opportunities for bone health assessment and intervention may be under recognised in COPD patients. Ways to improve this may include proformas and visual aids to prompt assessment and documentation of bone health, further education to increase awareness and greater access to densitometry resources in the community. In conclusion, this study highlights that further attention to patients’ bone health assessment and commencement of appropriate treatment is warranted. Admission to hospital or clinic review for such patients provide important opportunities for intervention.

160 TIME TO BIN ‘NEXT OF KIN’?—JUNIOR DOCTORS DEMONSTRATE POOR UNDERSTANDING OF THE TERM IN IRELAND

Background

‘Next of kin’ (NOK) is a term widely used in the healthcare setting in Ireland to indicate an individual that can be contacted in the event of an emergency when a patient is in hospital. While it has its origins in Irish inheritance law, the term confers no legal or decision-making authority to any other individuals on behalf of a patient in hospital. However, anecdotally, the term is commonly misunderstood with a false belief among healthcare staff that consent should be sought from the NOK when a patient is unable to do so. In this study we sought to assess current understanding of the term among Irish non-consultant hospital doctors (NCHDs).

Methods

Data was collected via an online survey, completed by NCHDs across a number of medical and surgical disciplines to investigate their understanding of the term. Descriptive analysis of data was performed in Excel.

Results

118 NCHDs completed the survey. While 110 (93.2%) believed a NOK was an emergency contact, 53 (44.9%) believed they assisted in decision making; 58 (49.2%) thought they could provide medical information about the patient. Forty-four doctors (37.3%) believed a NOK was permitted to make medical decisions while 59 (50%) felt they could provide consent on behalf of an incapacitated patient. Sixty-three (53.4%) believed a NOK had legal entitlement to information over and above that of another family member or friend.

Conclusion

This study highlights several misconceptions surrounding the term ‘next of kin’ in the Irish healthcare setting, particularly around the area of decision-making authority and consent. The term is confusing and unhelpful and should not be used in healthcare. ‘Contact person’ or ‘emergency contact’ are appropriate alternatives. Further education to NCHDs around consent and maintenance of patient autonomy is necessary.

172 ‘NCHD’S UNDERSTANDING OF THE ‘DYING WITH DIGNITY BILL”

Background

The Dying with Dignity Bill is potential legislation that would permit terminally ill people to avail of medical assistance to die in certain circumstances. It would give a medical practitioner the legal right to provide assistance to a qualifying person to end their life, thus changing the medical landscape as we know it. This project aimed to assess current understanding in non-consultant hospital doctors (NCHDs) of the Dying with Dignity Bill.

Methods

An online survey was distributed to NCHD’s across a range of disciplines to ascertain current knowledge of the Dying with Dignity Bill. Descriptive analysis of data was conducted on Excel.

Results

The survey was completed by 80 NCHDs. Of respondents 67.5% (n = 54) of respondents had heard of the Bill and 32.5% (n = 26) of them knew what it was. The Bill had not been read by 88% (n = 71) of respondents. Fifty seven per cent (n = 46) did not understand what was entailed in the Bill. The majority agreed (61.3%; n = 49) that it would impact their work as a clinician. Some 70.1% (n = 56) agreed that legislation was needed in this area. The majority answered neutral (45%; n = 35) that their profession were consulted in the creation of the Bill. It is believed that the Bill will not require a vote however 48% (n = 37) believed it would. However, the majority (72.7%, n = 56) answered correctly that the Bill had not been enacted yet. This Bill does not define the length of a ‘terminal illness’ yet 36.8% (n = 28) believed it to be within six months. It also states that it is the practitioner’s role to decide when somebody is palliative and only 54.5% (n = 42) knew this.

Conclusion

The Dying with Dignity Bill is poorly understood by NCHDs, despite it potentially having an impact on the role of hospital doctors in Ireland. Discussion and involvement of NCHD’s in the potential formation of this Bill is crucial.

Diabetes care and pregnancy outcomes for women with pregestational diabetes in Ireland

AIMS

Pre-gestational diabetes mellitus (PGDM) is associated with adverse outcomes. We aimed to examine pregnancies affected by PGDM; report on these pregnancy outcomes and compare outcomes for patients with type 1 versus type 2 diabetes mellitus; compare our findings to published Irish and United Kingdom (UK) data and identify potential areas for improvement.

METHODS

Between 2016 and 2018 information on 679 pregnancies from 415 women with type 1 Diabetes Mellitus and 244 women with type 2 diabetes was analysed. Data was collected on maternal characteristics; pregnancy preparation; glycaemic control; pregnancy related complications; foetal and maternal outcomes; unscheduled hospitalisations; congenital anomalies and perinatal deaths.

RESULTS

Only 15.9% of women were adequately prepared for pregnancy. Significant deficits were identified in availability and attendance at pre-pregnancy clinic, use of folic acid, attaining appropriate glycaemic targets and appropriate retinal screening. The majority of pregnancies (n = 567, 83.5%) resulted in a live birth but the large number of infants born large for gestational age (LGA) (n = 280, 49.4%), born prematurely <37 weeks and requiring neonatal intensive care unit (NICU) admission continue to be significant issues.

CONCLUSIONS

This retrospective cohort study identifies multiple targets for improvements in the provision of care to women with pre-gestational DM which are likely to translate into better pregnancy outcomes.

An Irish National Diabetes in Pregnancy Audit: aiming for best outcomes for women with diabetes

AIMS

The purpose of this study was to identify the number of pregnancies affected by pre-gestational diabetes in the Republic of Ireland; to report on pregnancy outcomes and to identify areas for improvement in care delivery and clinical outcomes.

METHODS

Healthcare professionals caring for women with pre-gestational diabetes during pregnancy were invited to participate in this retrospective study. Data pertaining to 185 pregnancies in women attending 15 antenatal centres nationally were collected and analysed. Included pregnancies had an estimated date of delivery between 1 January and 31 December 2015.

RESULTS

The cohort consisted of 122 (65.9%) women with Type 1 diabetes and 56 (30.3%) women with Type 2 diabetes. The remaining 7 (3.8%) pregnancies were to women with maturity-onset diabetes of the young (MODY) (n = 6) and post-transplant diabetes (n = 1). Overall women were poorly prepared for pregnancy and lapses in specific areas of service delivery including pre-pregnancy care and retinal screening were identified. The majority of pregnancies 156 (84.3%) resulted in a live birth. A total of 103 (65.5%) women had a caesarean delivery and 58 (36.9%) infants were large for gestational age.

CONCLUSIONS

This audit identifies clear areas for improvement in delivery of care for women with diabetes in the Republic of Ireland before and during pregnancy.

Effect of starvation and refeeding on the hepatopancreas of whiteleg shrimp Penaeus vannamei (Boone) using computer-assisted image analysis

Under normal farming conditions, shrimp can experience starvation periods attributable to disease outbreaks or adverse environmental conditions. Starvation leads to significant morphological changes in the hepatopancreas (HP), being the main organ for absorption and storage of nutrients. In the literature, limited research has described the effect on the HP of periods of starvation followed by refeeding and none in whiteleg shrimp (Penaeus vannamei) using computer-assisted image analysis (CAIA). This study describes the effect of starvation and starvation followed by refeeding on the HP of whiteleg shrimp using CAIA. Visiopharm^® software was used to quantify the following morphological parameters, measured as ratio to the total tissue area (TLA): total lumen area (TLA:TTA), haemocytic infiltration area in the intertubular spaces (HIA:TTA), B-cell vacuole area (VBA:TTA), lipid droplet area within R cells (LDA:TTA) and F-cell area (FCA:TTA). Significant changes were measured for HIA:TTA and LDA:TTA during starvation (increase in HIA:TTA associated with decrease in LDA:TTA) and starvation followed by refeeding (decrease in HIA:TTA associated with increase in LDA:TTA). In the future, HIA:TTA and LDA:TTA have the potential to be used in a pre-emptive manner to monitor the health of the HP, facilitate early diagnosis of diseases and study the pathophysiology of the organ.

Use of computer-assisted image analysis for semi-quantitative histology of the hepatopancreas in whiteleg shrimp Penaeus vannamei (Boone)

Despite the increasing use of novel molecular techniques in pathology, histology remains the standard method for monitoring tissue alterations and for assessing pathology. Histopathological evaluation is generally laborious and subjective with risk of discrepancies in semi-quantitative scoring between pathologists. In contrast, computer-assisted image analysis (CAIA) is potentially faster, more objective and thus suitable for routine screening. Limited research has been carried out on CAIA in crustacean histopathology, and the methods described were not fully automated. Therefore, the aim of this study was to develop CAIA in whiteleg shrimp (Penaeus vannamei) for the study of the hepatopancreas. Paraffin sections were immunohistochemically stained with monoclonal antibodies WSH8 against haemocytes and counterstained with Mayer's haematoxylin for detection of haemocytes and B-cell vacuoles, and modified toluidine blue protocol was used for detection of F-cells; frozen sections were stained with Oil Red O for detection of lipid droplets within R-cells. Visiopharm^® software was used to develop and validated protocols for the quantification of morphological parameters (areas of haemocyte infiltration, F-cells, B-cell vacuoles, lipid droplets and their ratios to total tissue area and total lumen area). These protocols enable the future use of CAIA for determination of the nutritional and pathological condition of this organ.

Optimization of fixation methods for image analysis of the hepatopancreas in whiteleg shrimp, Penaeus vannamei (Boone)

Pathology in penaeid shrimps relies on histology, which is subjective, time-consuming and difficult to grade in a reproducible manner. Automated image analysis is faster, objective and suitable for routine screening; however, it requires standardized protocols. The first critical step is proper fixation of the target tissue. Bell & Lightner's (A Handbook of Normal Penaeid Shrimp Histology, 1988, The World Aquaculture Society, Baton Rouge) fixation protocol, widely used for routine histology of paraffin sections, is not optimized for image analysis, and no protocol for frozen sections is described in the available literature. Therefore, the aim of this study was to optimize fixation of the hepatopancreas (HP) from whiteleg shrimp (Penaeus vannamei) for both paraffin and frozen sections using a semiquantitative scoring system. For paraffin sections, four injection volumes and three injection methods were compared, for frozen sections, four freezing methods and four fixation methods. For paraffin sections, optimal fixation was achieved by increasing threefold the fixative volume recommended by Bell and Lightner, from 10% to 30% of the shrimp body weight, combined with single injection into the HP. Optimal fixation for frozen sections was achieved by freezing the cephalothorax with liquid nitrogen, followed by fixation of the section with 60% isopropanol. These optimized methods enable the future use of image analysis and improve classical histology.

A primary phosphorus-deficient skeletal phenotype in juvenile Atlantic salmon Salmo salar: the uncoupling of bone formation and mineralization

To understand the effect of low dietary phosphorus (P) intake on the vertebral column of Atlantic salmon Salmo salar, a primary P deficiency was induced in post-smolts. The dietary P provision was reduced by 50% for a period of 10 weeks under controlled conditions. The animal's skeleton was subsequently analysed by radiology, histological examination, histochemical detection of minerals in bones and scales and chemical mineral analysis. This is the first account of how a primary P deficiency affects the skeleton in S. salar at the cellular and at the micro-anatomical level. Animals that received the P-deficient diet displayed known signs of P deficiency including reduced growth and soft, pliable opercula. Bone and scale mineral content decreased by c. 50%. On radiographs, vertebral bodies appear small, undersized and with enlarged intervertebral spaces. Contrary to the X-ray-based diagnosis, the histological examination revealed that vertebral bodies had a regular size and regular internal bone structures; intervertebral spaces were not enlarged. Bone matrix formation was continuous and uninterrupted, albeit without traces of mineralization. Likewise, scale growth continues with regular annuli formation, but new scale matrix remains without minerals. The 10 week long experiment generated a homogeneous osteomalacia of vertebral bodies without apparent induction of skeletal malformations. The experiment shows that bone formation and bone mineralization are, to a large degree, independent processes in the fish examined. Therefore, a deficit in mineralization must not be the only cause of the alterations of the vertebral bone structure observed in farmed S. salar. It is discussed how the observed uncoupling of bone formation and mineralization helps to better diagnose, understand and prevent P deficiency-related malformations in farmed S. salar.

Investigating the underlying mechanisms of temperature-related skin diseases in Atlantic salmon, Salmo salar L., as measured by quantitative histology, skin transcriptomics and composition

Skin integrity is recognized as of vital consideration for both animal welfare and final product quality of farmed fish. This study examines the effects of three different rearing temperatures (4, 10 and 16 °C) on the skin of healthy Atlantic salmon post-smolts. Changes in skin condition were assessed by the means of skin composition analyses, quantitative histology assessments and transcriptome analysis. Level of protein, vitamin C and vitamin E was significantly higher at 16 °C compared with 4 °C. Quantitative histology measurements showed that the epidermal thickness decreased from low to high temperature, whereas the epidermal area comprising mucous cells increased. The difference was only significant between 4 and 16 °C. Both high and low temperature exhibited significant changes in the skin transcriptome. A number of immune-related transcripts responded at both temperatures. Contrary to well-described immunosuppressive effects of low water temperature on systemic immunity, a subtle increase in skin-mediated immunity was observed, suggesting a pre-activation of the mucosal system at 4 °C. Upregulation of a number of heat-shock proteins correlating with a decrease in epidermal thickness suggested a stress response in the skin at high temperature. The results demonstrate distinctive temperature-related effects on the skin of Atlantic salmon.

Intensive care in a general hospital: demographics, utilization and outcomes

INTRODUCTION

Intensive care units (ICU) in Irish academic centres are known to fare as well as their international counterparts. Our aim in this study was to characterise the role and outcomes of an ICU in a smaller Irish hospital and to compare these to international best practice.

METHODS

We reviewed admissions of patients to the ICU of St. Luke's Hospital, Kilkenny. Patient demographics, indications for admission, and outcomes were all recorded and analysed. Sequential organ failure assessment (SOFA) scores were calculated.

RESULTS

Forty-three patients were included in our study, 33 (76.7 %) of which were emergency admissions. Median length of stay was 2 days. The observed mortality rate in our cohort was 20.9 %. The median SOFA score in patients admitted was 7. Higher median SOFA scores on admission were predictive of mortality. The ICU occupancy rate during the duration of our study was 98 %, with only 15 (35.7 %) of admissions to ICU occurring within core working hours.

CONCLUSION

Critical care can be provided safely and in line with current best practice in smaller Irish hospitals. There is a cohort of patients for whom care may be best provided in a tertiary centre, how best to provide for these patients will likely be achieved by early identification (e.g. with SOFA score). Bed capacity issues remain problematic.

Bradykinin infusion in chronic cardiac failure and the effects of captopril

BACKGROUND

Patients with chronic cardiac failure (CCF) have abnormal vascular responses. Bradykinin (BK) is thought to contribute to the vasodilator effects of ACE inhibitors, but the effect of BK itself in patients with CCF has not been examined.

METHODS

We studied the responses to infused BK at 10, 30 and 100 pmol min(-1) in patients with CCF (n=10) and controls (n=10). The slope of the dose-response curve was used for comparisons between the groups. Forearm blood flow (FBF) was measured by venous occlusion plethysmography.

RESULTS

Following BK, vasodilatation was observed in both groups as the slopes were positive in all, but the difference between the groups was not significant (P=0.77). The study was repeated with the co-administration of 4 micromol min(-1) of N(G)-monomethyl L-arginine (L-NMMA). The vasodilator response to BK was reduced in both groups, and the effect was somewhat greater in the patient group (P=0.23). The vasodilator response to the endothelium-independent vasodilator sodium nitroprusside was slightly less in the patient group (P=0.08). The patients only then underwent repeat infusion of BK before and after a single oral dose of captopril 12.5 mg or placebo. Following captopril, the vasodilator response to BK was unchanged when compared to placebo (difference between slopes, P=0.53).

CONCLUSIONS

BK produces dose-dependent vasodilatation in both patients with CCF and controls; there was no difference in the responses, which were antagonised by L-NMMA and therefore in part NO (endothelium)-dependent. The responses were also unchanged after administration of an ACE inhibitor (captopril).

Vasoconstriction to endogenous endothelin-1 is impaired in patients with type II diabetes mellitus

Endothelin-1 has potent vasoconstrictor and vasopressor actions contributing to basal vascular tone and maintenance of blood pressure acting predominantly through endothelin-A receptors. Endothelin antagonists may be of value in the treatment of hypertension and heart failure. However, the role of endothelin-1 in the regulation of vascular tone and the potential benefits of endothelin antagonists in non-insulin-dependent diabetes mellitus (Type II diabetes) are less clear. Vasoconstriction to exogenous endothelin-1 is impaired in Type II diabetes. The purpose of this study was to determine whether vasoconstriction to endogenous endothelin-1 acting through the endothelin-A receptor is impaired in Type II diabetes. In ten patients with Type II diabetes and nine controls the endothelin-A receptor antagonist BQ123 was infused intra-arterially at 100 nmol/min for 60 min followed by normal saline for 30 min. Forearm blood flow was measured using venous occlusion plethysmography. Control subjects showed gradual onset of vasodilation in response to BQ123 (P < 0.001). Diabetic subjects, however, showed no significant response (P > 0.05). There was a significant difference between the diabetic and control groups (P < 0.05). Blockade of the endothelin-A receptor is associated with impaired vasodilation in Type II diabetes indicating vasoconstriction to endogenous endothelin-1 mediated by the endothelin-A receptor is impaired.

Vasoconstriction to endothelin-1 is blunted in non-insulin-dependent diabetes: a dose-response study

The haemodynamic hypothesis for the pathogenesis of diabetic microangiopathy argues that an initial increase in microvascular blood flow leads to microvascular sclerosis and disturbed autoregulation. Endothelin-1 (ET-1) is an endothelium-derived vasoconstrictor peptide that contributes to basal vascular tone. Impairment of the vasoconstrictor response to ET-1 could result in hyperperfusion and subsequent microvascular damage. The purpose of this study was to determine whether vascular responses to ET-1 are impaired in patients with non-insulin-dependent diabetes mellitus (type 2 diabetes). Ten patients with type 2 diabetes and nine control subjects underwent brachial artery cannulation. Forearm blood flow was measured using strain-gauge venous occlusion plethysmography. ET-1 in three doses of 5, 10, and 20 pmol/min and 0.9% saline placebo was infused in a balanced double-blind randomised manner. Vascular smooth muscle function also was assessed using sodium nitroprusside. Control subjects showed vasoconstriction to ET-1 of 5 (p < 0.05), 10 (p < 0.05), and 20 pmol/min (p < 0.01). In the diabetic group, there was no significant response to ET-1 at 5 pmol/min (p > 0.05); however, significant vasoconstriction developed at 10 and 20 pmol/min (p < 0.01). There was a significant difference in response to ET-1 at 5 pmol/min between the diabetic and control groups (p < 0.05). Responses to sodium nitroprusside were similar in both groups (p > 0.05). Patients with type 2 diabetes have a blunted vasoconstrictor response to ET-1 despite preserved vascular smooth muscle function.

Forearm reactive hyperaemia is not mediated by nitric oxide in healthy volunteers

AIMS

To determine the role of nitric oxide (NO) in forearm reactive hyperaemia in healthy human subjects.

METHODS

Ten healthy subjects aged 19-34 years underwent brachial artery cannulation. Forearm circulatory arrest was achieved by means of an upper arm cuff inflated to 200 mmHg for 5 min. The blood flow responses during reactive hyperaemia were measured using venous occlusion plethysmography following a 10 min intra-arterial infusion of 8 micromol min-1 N-monomethyl L-arginine (L-NMMA) and following matching placebo administered in random order. Results were analysed by repeated measures anova and t-tests.

RESULTS

L-NMMA resulted in a significant reduction of basal forearm blood flow indicating inhibition of basal NO release (P=0.005). There was no significant difference between the blood flow responses during reactive hyperaemia following L-NMMA and placebo (P=0.97).

CONCLUSIONS

Nitric oxide production does not make a significant contribution to the vasodilatation associated with reactive hyperaemia in the human forearm.

Effect of methionine supplementation on endothelial function, plasma homocysteine, and lipid peroxidation

BACKGROUND

Acetaminophen (paracetamol) poisoning is a major source of morbidity and mortality. It has been proposed that methionine be incorporated into acetaminophen tablets routinely as a protective mechanism. Methionine has been shown to be effective in the treatment of acetaminophen toxicity and a combination preparation of acetaminophen and methionine may prevent toxicity. However, there has been some concern that chronic methionine supplementation may be associated with vascular disease. The aim of the study was to investigate if methionine supplementation causes changes in endothelial function, plasma homocysteine, or lipid peroxidation which may be associated with atherosclerosis.

METHODS

Sixteen healthy volunteers were studied. Forearm blood flow in response to local intra-arterial infusion of acetylcholine to assess endothelium-dependent vasodilatation and sodium nitroprusside to assess endothelium-independent vasodilatation was measured by venous occlusion plethysmography. Plasma homocysteine and lipid peroxidation, measured as thiobarbituric acid reactive substances, were measured using high-performance liquid chromatography. Forearm vascular responses, plasma homocysteine concentrations, and thiobarbituric acid reactive substances were measured at baseline and following methionine supplementation.

RESULTS

There was no significant difference in endothelial-dependent vascular responses after acute (methionine 250 mg orally, p > 0.05), 1 month of low-dose (methionine 250 mg daily, p > 0.05), or 1 week of high-dose (methionine 100 mg/kg daily, p > 0.05) methionine administration. There was no significant difference in plasma homocysteine concentrations after acute (p > 0.05) or 1 month of low-dose (p > 0.05) methionine administration. However, 1 week of high-dose methionine (100 mg/kg) administration daily significantly increased homocysteine concentrations (p < 0.0015). Thiobarbituric acid reactive substances were unchanged during the period of study (p > 0.05).

CONCLUSIONS

Methionine supplementation does not impair endothelial-dependent vascular responses in healthy volunteers. Although high-dose methionine administration causes elevation of plasma homocysteine concentrations, doses similar to those used in combination preparations with acetaminophen do not affect plasma homocysteine concentrations.

Integrating information literacies into an undergraduate nursing programme

The development of support for a more research-based approach to care has created the imperative for nursing education to tackle the issue of information literacy. Information literacy means the ability to locate, evaluate and apply information in critical thinking and problem solving. This paper outlines and provides a rationale for a curriculum-integrated information literacy programme, implemented in the pre-registration Bachelor of Nursing course at the University of Wollongong, NSW, Australia. It also describes a multidimensional evaluation process for determining nursing students' growth in cognitive and affective domains. Results of the programme evaluation will be featured in a future paper.

Abnormal vascular responses in human chronic cardiac failure are both endothelium dependent and endothelium independent

OBJECTIVE

To study underlying vascular responses in chronic heart failure in patients without ACE inhibitor treatment, and to compare them with age matched controls.

DESIGN

Forearm blood flow was studied using venous occlusion plethysmography in patients with chronic heart failure (n = 12) and matched controls (n = 13), after infusion of L-NMMA (a nitric oxide synthase inhibitor), glyceryl trinitrate (an endothelium independent vasodilator), and serotonin (an endothelium dependent vasodilator).

RESULTS

L-NMMA produced significant vasoconstriction in normal subjects (forearm blood flow reduced by 24%), but not in patients (6%; difference between groups p < 0.03). The vasodilator responses to glyceryl trinitrate were impaired in patients (p < 0.02). In normal controls, serotonin produced initial dilatation, followed by vasoconstriction at high doses. In patients, no vasodilator responses were observed, only late vasoconstriction (p < 0.03).

CONCLUSIONS

The vascular responses of patients are confirmed as being abnormal. The lack of response to L-NMMA suggests that nitric oxide does not contribute to basal vascular tone in patients with chronic heart failure. The responses to glyceryl trinitrate and to serotonin suggest that there is both smooth muscle and endothelial dysfunction in patients with chronic heart failure.

Sources of inaccuracy in the use of the Hawksley random-zero sphygmomanometer

OBJECTIVE

To identify possible causes of inaccuracy in the use of the Hawksley random-zero sphygmomanometer and methods that could reduce this.

METHODS

Four Hawksley random-zero sphygmomanometers were compared with a standard sphygmomanometer under static conditions. Two methods (standard and rapid) were used to release pressure from the inflated cuff with pressures recorded by independent blinded observers. The rate at which the hand valve released pressure was analysed. The effects of varying filling times and pressures on the size of the final zero correction were investigated.

RESULTS

The Hawksley devices all under-recorded pressure compared with that measured by using a standard machine. A rapid means of pressure release approximately halved this error in each case. Pressure release through the hand valve was shown to have a characteristic and prolonged exponential decay. Using low filling times and pressures reduced the observed range of zeros seen, with the production of a correlation between the size of the zero and the inflation pressure used.

CONCLUSION

These findings suggest that overestimation of the final zero correction is a common and major source of error in the use of the Hawksley sphygmomanometer. A simple change in the design of the final pressure release would improve the machine's reliability in clinical usage. The machine's zero mechanism is susceptible to unintentional misuse. Such misuse could occur when the machine is used in accordance with current sphygmomanometry guidelines.

Forearm endothelium-dependent vascular responses and the potassium-ATP channel

AIMS

Vasodilation to acetylcholine is mediated at least in part by endothelium-derived hyperpolarising factor (EDHF) which causes membrane hyperpolarisation by activating potassium channels. It is however uncertain which potassium channel mediates this effect. The aim of this study was to determine the role of the potassium-ATP (K(+)-ATP) channel in mediating endothelium-dependent vascular responses to acetylcholine.

METHODS

In 10 healthy volunteers acetylcholine, an endothelium-dependent vasodilator, and sodium nitroprusside as a control assessing endothelium-independent vasodilatation were infused into the non-dominant brachial artery. Forearm blood flow (FBF) in response to each dose was measured by strain-gauge venous occlusion plethysmography. The K(+)-ATP channel blocker glipizide (2.5 mg) was then administered orally. After 45 min the infusions with FBF measurements were repeated.

RESULTS

Acetylcholine (P < 0.01) and sodium nitroprusside (P < 0.01) both caused an increase in FBF. There was no significant difference in vascular responses to acetylcholine (P > 0.05) or sodium nitroprusside (P > 0.05) following K(+)-ATP channel blockade.

CONCLUSIONS

The K(+)-ATP channel does not modulate forearm arteriolar endothelium-dependent responses in healthy volunteers and therefore does not play a role in membrane hyperpolarisation.

Forearm vascular responses to serotonin are not mediated by products of cyclooxygenase

The involvement of cyclooxygenase-derived substances in the forearm arteriolar responses to serotonin was determined in 10 healthy male volunteers. Serotonin was infused in five incremental doses (0.003-30 micrograms min-1) for 2 min each into the brachial artery of the non-dominant forearm. Forearm blood flow (FBF) responses to each dose were measured by strain-gauge venous occlusion plethysmography. The cyclooxygenase inhibitor indomethacin (100 mg) was administered orally following the serotonin infusions. After 90 min the serotonin infusions were repeated and FBF responses measured. Serotonin caused a biphasic response with vasodilatation occurring at low doses (0.003-3 micrograms min-1, P < 0.01) and vasoconstriction occurring at the highest dose (P < 0.01). There was no significant difference in vascular response to serotonin following cyclooxygenase inhibition. In conclusion, cyclooxygenase products are not involved in the forearm vascular responses to serotonin in healthy human subjects.

Impaired vasoconstriction to endothelin 1 in patients with NIDDM

Microvascular disease is an important cause of morbidity in diabetes. There is evidence that impaired autoregulation of blood flow is involved in the pathogenesis of diabetic microangiopathy. The vascular endothelium plays a central role in the regulation of vascular tone. Endothelin (ET)-1 is a potent endothelium-derived vasoconstrictor substance that contributes to basal vascular tone. Impaired vasoconstriction in response to endogenous ET could result in hyperperfusion and subsequent microvascular damage. The purpose of our study was to determine whether vascular responses to locally administered ET-1 are impaired in NIDDM. Nine patients with NIDDM and 12 control subjects underwent cannulation of the nondominant brachial artery. Forearm blood flow (FBF) was measured at baseline and during the drug infusion using strain-gauge venous occlusion plethysmography. ET-1 (5 pmol/min) was infused for 60 min at a rate of 1 ml/min. FBF was measured during the first 5 min of the infusion and at 5-min intervals thereafter. Results were expressed as change in FBF from baseline (ml.100 ml-1.min-1) and were analyzed using repeated measures analysis of variance and Dunnett's test of multiple comparisons. Control subjects showed a gradual onset of vasoconstriction in response to ET-1, which reached maximum at 35 min (1.1 ml.100 ml-1.min-1; P < 0.01). There was no reduction in FBF in response to ET-1 in the diabetic group. The differences between the diabetic and control groups were significant (P < 0.03). In conclusion, ET-1 infused locally at 5 pmol/min does not cause vasoconstriction in patients with NIDDM.